sys-kernel/linux-{image,sources}-redcore-lts : revision bump, drop and disable BFQ-SQ

5 files changed, 7 insertions, 48338 deletions

diff --git a/sys-kernel/linux-image-redcore-lts/files/4.14-0001-BFQ-v8r12-20171108.patch b/sys-kernel/linux-image-redcore-lts/files/4.14-0001-BFQ-v8r12-20171108.patch
deleted file mode 100644
index db7d064b..00000000
--- a/sys-kernel/linux-image-redcore-lts/files/4.14-0001-BFQ-v8r12-20171108.patch
+++ /dev/null
@@ -1,25199 +0,0 @@
-From c21f53f17430230dab50df29b8ea1b71f99d09d6 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@unimore.it>
-Date: Tue, 7 Apr 2015 13:39:12 +0200
-Subject: [PATCH 01/51] Add BFQ-v8r12
-
-This commit is the result of the following operations.
-
-1. The squash of all the commits between "block: cgroups, kconfig,
-build bits for BFQ-v7r11-4.5.0" and BFQ-v8r12 in the branch
-bfq-mq-v8-v4.11
-
-2. The renaming of two files (block/bfq-cgroup.c ->
-block/bfq-cgroup-included.c and block/bfq-iosched.c ->
-block/bfq-sq-iosched.c) and of one option (CONFIG_BFQ_GROUP_IOSCHED ->
-CONFIG_BFQ_SQ_GROUP_IOSCHED), to avoid name clashes. These name
-clashes are due to the presence of bfq in mainline from 4.12.
-
-3. The modification of block/Makefile and block/Kconfig.iosched to
-comply with the above renaming.
-
-Signed-off-by: Mauro Andreolini <mauro.andreolini@unimore.it>
-Signed-off-by: Arianna Avanzini <avanzini@google.com>
-Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- Makefile                    |    2 +-
- block/Kconfig.iosched       |   31 +
- block/bfq-cgroup-included.c | 1190 ++++++++++
- block/bfq-ioc.c             |   36 +
- block/bfq-sched.c           | 2002 ++++++++++++++++
- block/bfq-sq-iosched.c      | 5379 +++++++++++++++++++++++++++++++++++++++++++
- block/bfq.h                 |  948 ++++++++
- include/linux/blkdev.h      |    2 +-
- 9 files changed, 9589 insertions(+), 2 deletions(-)
- create mode 100644 block/bfq-cgroup-included.c
- create mode 100644 block/bfq-ioc.c
- create mode 100644 block/bfq-sched.c
- create mode 100644 block/bfq-sq-iosched.c
- create mode 100644 block/bfq.h
-
-diff --git a/block/Kconfig.iosched b/block/Kconfig.iosched
-index a4a8914bf7a4..9e3f4c2f7390 100644
---- a/block/Kconfig.iosched
-+++ b/block/Kconfig.iosched
-@@ -40,6 +40,26 @@ config CFQ_GROUP_IOSCHED
- 	---help---
- 	  Enable group IO scheduling in CFQ.
- 
-+config IOSCHED_BFQ_SQ
-+	tristate "BFQ-SQ I/O scheduler"
-+	default n
-+	---help---
-+	The BFQ-SQ I/O scheduler (for legacy blk: SQ stands for
-+	SingleQueue) distributes bandwidth among all processes
-+	according to their weights, regardless of the device
-+	parameters and with any workload. It also guarantees a low
-+	latency to interactive and soft real-time applications.
-+	Details in Documentation/block/bfq-iosched.txt
-+
-+config BFQ_SQ_GROUP_IOSCHED
-+	bool "BFQ-SQ hierarchical scheduling support"
-+	depends on IOSCHED_BFQ_SQ && BLK_CGROUP
-+	default n
-+	---help---
-+
-+	Enable hierarchical scheduling in BFQ-SQ, using the blkio
-+	(cgroups-v1) or io (cgroups-v2) controller.
-+
- choice
- 
- 	prompt "Default I/O scheduler"
-@@ -54,6 +74,16 @@ choice
- 	config DEFAULT_CFQ
- 		bool "CFQ" if IOSCHED_CFQ=y
- 
-+	config DEFAULT_BFQ_SQ
-+		bool "BFQ-SQ" if IOSCHED_BFQ_SQ=y
-+		help
-+		  Selects BFQ-SQ as the default I/O scheduler which will be
-+		  used by default for all block devices.
-+		  The BFQ-SQ I/O scheduler aims at distributing the bandwidth
-+		  as desired, independently of the disk parameters and with
-+		  any workload. It also tries to guarantee low latency to
-+		  interactive and soft real-time applications.
-+
- 	config DEFAULT_NOOP
- 		bool "No-op"
- 
-@@ -63,6 +93,7 @@ config DEFAULT_IOSCHED
- 	string
- 	default "deadline" if DEFAULT_DEADLINE
- 	default "cfq" if DEFAULT_CFQ
-+	default "bfq-sq" if DEFAULT_BFQ_SQ
- 	default "noop" if DEFAULT_NOOP
- 
- config MQ_IOSCHED_DEADLINE
-diff --git a/block/Makefile b/block/Makefile
-index 6a56303b9925..59026b425791 100644
---- a/block/Makefile
-+++ b/block/Makefile
-@@ -24,6 +24,7 @@ obj-$(CONFIG_MQ_IOSCHED_DEADLINE)	+= mq-deadline.o
- obj-$(CONFIG_MQ_IOSCHED_KYBER)	+= kyber-iosched.o
- bfq-y				:= bfq-iosched.o bfq-wf2q.o bfq-cgroup.o
- obj-$(CONFIG_IOSCHED_BFQ)	+= bfq.o
-+obj-$(CONFIG_IOSCHED_BFQ_SQ)	+= bfq-sq-iosched.o
- 
- obj-$(CONFIG_BLOCK_COMPAT)	+= compat_ioctl.o
- obj-$(CONFIG_BLK_CMDLINE_PARSER)	+= cmdline-parser.o
-diff --git a/block/bfq-cgroup-included.c b/block/bfq-cgroup-included.c
-new file mode 100644
-index 000000000000..af7c216a3540
---- /dev/null
-+++ b/block/bfq-cgroup-included.c
-@@ -0,0 +1,1190 @@
-+/*
-+ * BFQ: CGROUPS support.
-+ *
-+ * Based on ideas and code from CFQ:
-+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
-+ *
-+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
-+ *		      Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2016 Paolo Valente <paolo.valente@linaro.org>
-+ *
-+ * Licensed under the GPL-2 as detailed in the accompanying COPYING.BFQ
-+ * file.
-+ */
-+
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+
-+/* bfqg stats flags */
-+enum bfqg_stats_flags {
-+	BFQG_stats_waiting = 0,
-+	BFQG_stats_idling,
-+	BFQG_stats_empty,
-+};
-+
-+#define BFQG_FLAG_FNS(name)						\
-+static void bfqg_stats_mark_##name(struct bfqg_stats *stats)	\
-+{									\
-+	stats->flags |= (1 << BFQG_stats_##name);			\
-+}									\
-+static void bfqg_stats_clear_##name(struct bfqg_stats *stats)	\
-+{									\
-+	stats->flags &= ~(1 << BFQG_stats_##name);			\
-+}									\
-+static int bfqg_stats_##name(struct bfqg_stats *stats)		\
-+{									\
-+	return (stats->flags & (1 << BFQG_stats_##name)) != 0;		\
-+}									\
-+
-+BFQG_FLAG_FNS(waiting)
-+BFQG_FLAG_FNS(idling)
-+BFQG_FLAG_FNS(empty)
-+#undef BFQG_FLAG_FNS
-+
-+/* This should be called with the queue_lock held. */
-+static void bfqg_stats_update_group_wait_time(struct bfqg_stats *stats)
-+{
-+	unsigned long long now;
-+
-+	if (!bfqg_stats_waiting(stats))
-+		return;
-+
-+	now = sched_clock();
-+	if (time_after64(now, stats->start_group_wait_time))
-+		blkg_stat_add(&stats->group_wait_time,
-+			      now - stats->start_group_wait_time);
-+	bfqg_stats_clear_waiting(stats);
-+}
-+
-+/* This should be called with the queue_lock held. */
-+static void bfqg_stats_set_start_group_wait_time(struct bfq_group *bfqg,
-+						 struct bfq_group *curr_bfqg)
-+{
-+	struct bfqg_stats *stats = &bfqg->stats;
-+
-+	if (bfqg_stats_waiting(stats))
-+		return;
-+	if (bfqg == curr_bfqg)
-+		return;
-+	stats->start_group_wait_time = sched_clock();
-+	bfqg_stats_mark_waiting(stats);
-+}
-+
-+/* This should be called with the queue_lock held. */
-+static void bfqg_stats_end_empty_time(struct bfqg_stats *stats)
-+{
-+	unsigned long long now;
-+
-+	if (!bfqg_stats_empty(stats))
-+		return;
-+
-+	now = sched_clock();
-+	if (time_after64(now, stats->start_empty_time))
-+		blkg_stat_add(&stats->empty_time,
-+			      now - stats->start_empty_time);
-+	bfqg_stats_clear_empty(stats);
-+}
-+
-+static void bfqg_stats_update_dequeue(struct bfq_group *bfqg)
-+{
-+	blkg_stat_add(&bfqg->stats.dequeue, 1);
-+}
-+
-+static void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg)
-+{
-+	struct bfqg_stats *stats = &bfqg->stats;
-+
-+	if (blkg_rwstat_total(&stats->queued))
-+		return;
-+
-+	/*
-+	 * group is already marked empty. This can happen if bfqq got new
-+	 * request in parent group and moved to this group while being added
-+	 * to service tree. Just ignore the event and move on.
-+	 */
-+	if (bfqg_stats_empty(stats))
-+		return;
-+
-+	stats->start_empty_time = sched_clock();
-+	bfqg_stats_mark_empty(stats);
-+}
-+
-+static void bfqg_stats_update_idle_time(struct bfq_group *bfqg)
-+{
-+	struct bfqg_stats *stats = &bfqg->stats;
-+
-+	if (bfqg_stats_idling(stats)) {
-+		unsigned long long now = sched_clock();
-+
-+		if (time_after64(now, stats->start_idle_time))
-+			blkg_stat_add(&stats->idle_time,
-+				      now - stats->start_idle_time);
-+		bfqg_stats_clear_idling(stats);
-+	}
-+}
-+
-+static void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg)
-+{
-+	struct bfqg_stats *stats = &bfqg->stats;
-+
-+	stats->start_idle_time = sched_clock();
-+	bfqg_stats_mark_idling(stats);
-+}
-+
-+static void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg)
-+{
-+	struct bfqg_stats *stats = &bfqg->stats;
-+
-+	blkg_stat_add(&stats->avg_queue_size_sum,
-+		      blkg_rwstat_total(&stats->queued));
-+	blkg_stat_add(&stats->avg_queue_size_samples, 1);
-+	bfqg_stats_update_group_wait_time(stats);
-+}
-+
-+static struct blkcg_policy blkcg_policy_bfq;
-+
-+/*
-+ * blk-cgroup policy-related handlers
-+ * The following functions help in converting between blk-cgroup
-+ * internal structures and BFQ-specific structures.
-+ */
-+
-+static struct bfq_group *pd_to_bfqg(struct blkg_policy_data *pd)
-+{
-+	return pd ? container_of(pd, struct bfq_group, pd) : NULL;
-+}
-+
-+static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg)
-+{
-+	return pd_to_blkg(&bfqg->pd);
-+}
-+
-+static struct bfq_group *blkg_to_bfqg(struct blkcg_gq *blkg)
-+{
-+	struct blkg_policy_data *pd = blkg_to_pd(blkg, &blkcg_policy_bfq);
-+
-+	return pd_to_bfqg(pd);
-+}
-+
-+/*
-+ * bfq_group handlers
-+ * The following functions help in navigating the bfq_group hierarchy
-+ * by allowing to find the parent of a bfq_group or the bfq_group
-+ * associated to a bfq_queue.
-+ */
-+
-+static struct bfq_group *bfqg_parent(struct bfq_group *bfqg)
-+{
-+	struct blkcg_gq *pblkg = bfqg_to_blkg(bfqg)->parent;
-+
-+	return pblkg ? blkg_to_bfqg(pblkg) : NULL;
-+}
-+
-+static struct bfq_group *bfqq_group(struct bfq_queue *bfqq)
-+{
-+	struct bfq_entity *group_entity = bfqq->entity.parent;
-+
-+	return group_entity ? container_of(group_entity, struct bfq_group,
-+					   entity) :
-+			      bfqq->bfqd->root_group;
-+}
-+
-+/*
-+ * The following two functions handle get and put of a bfq_group by
-+ * wrapping the related blk-cgroup hooks.
-+ */
-+
-+static void bfqg_get(struct bfq_group *bfqg)
-+{
-+	return blkg_get(bfqg_to_blkg(bfqg));
-+}
-+
-+static void bfqg_put(struct bfq_group *bfqg)
-+{
-+	return blkg_put(bfqg_to_blkg(bfqg));
-+}
-+
-+static void bfqg_stats_update_io_add(struct bfq_group *bfqg,
-+				     struct bfq_queue *bfqq,
-+				     unsigned int op)
-+{
-+	blkg_rwstat_add(&bfqg->stats.queued, op, 1);
-+	bfqg_stats_end_empty_time(&bfqg->stats);
-+	if (!(bfqq == ((struct bfq_data *)bfqg->bfqd)->in_service_queue))
-+		bfqg_stats_set_start_group_wait_time(bfqg, bfqq_group(bfqq));
-+}
-+
-+static void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op)
-+{
-+	blkg_rwstat_add(&bfqg->stats.queued, op, -1);
-+}
-+
-+static void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op)
-+{
-+	blkg_rwstat_add(&bfqg->stats.merged, op, 1);
-+}
-+
-+static void bfqg_stats_update_completion(struct bfq_group *bfqg,
-+			uint64_t start_time, uint64_t io_start_time,
-+			unsigned int op)
-+{
-+	struct bfqg_stats *stats = &bfqg->stats;
-+	unsigned long long now = sched_clock();
-+
-+	if (time_after64(now, io_start_time))
-+		blkg_rwstat_add(&stats->service_time, op,
-+				now - io_start_time);
-+	if (time_after64(io_start_time, start_time))
-+		blkg_rwstat_add(&stats->wait_time, op,
-+				io_start_time - start_time);
-+}
-+
-+/* @stats = 0 */
-+static void bfqg_stats_reset(struct bfqg_stats *stats)
-+{
-+	/* queued stats shouldn't be cleared */
-+	blkg_rwstat_reset(&stats->merged);
-+	blkg_rwstat_reset(&stats->service_time);
-+	blkg_rwstat_reset(&stats->wait_time);
-+	blkg_stat_reset(&stats->time);
-+	blkg_stat_reset(&stats->avg_queue_size_sum);
-+	blkg_stat_reset(&stats->avg_queue_size_samples);
-+	blkg_stat_reset(&stats->dequeue);
-+	blkg_stat_reset(&stats->group_wait_time);
-+	blkg_stat_reset(&stats->idle_time);
-+	blkg_stat_reset(&stats->empty_time);
-+}
-+
-+/* @to += @from */
-+static void bfqg_stats_add_aux(struct bfqg_stats *to, struct bfqg_stats *from)
-+{
-+	if (!to || !from)
-+		return;
-+
-+	/* queued stats shouldn't be cleared */
-+	blkg_rwstat_add_aux(&to->merged, &from->merged);
-+	blkg_rwstat_add_aux(&to->service_time, &from->service_time);
-+	blkg_rwstat_add_aux(&to->wait_time, &from->wait_time);
-+	blkg_stat_add_aux(&from->time, &from->time);
-+	blkg_stat_add_aux(&to->avg_queue_size_sum, &from->avg_queue_size_sum);
-+	blkg_stat_add_aux(&to->avg_queue_size_samples,
-+			  &from->avg_queue_size_samples);
-+	blkg_stat_add_aux(&to->dequeue, &from->dequeue);
-+	blkg_stat_add_aux(&to->group_wait_time, &from->group_wait_time);
-+	blkg_stat_add_aux(&to->idle_time, &from->idle_time);
-+	blkg_stat_add_aux(&to->empty_time, &from->empty_time);
-+}
-+
-+/*
-+ * Transfer @bfqg's stats to its parent's dead_stats so that the ancestors'
-+ * recursive stats can still account for the amount used by this bfqg after
-+ * it's gone.
-+ */
-+static void bfqg_stats_xfer_dead(struct bfq_group *bfqg)
-+{
-+	struct bfq_group *parent;
-+
-+	if (!bfqg) /* root_group */
-+		return;
-+
-+	parent = bfqg_parent(bfqg);
-+
-+	lockdep_assert_held(bfqg_to_blkg(bfqg)->q->queue_lock);
-+
-+	if (unlikely(!parent))
-+		return;
-+
-+	bfqg_stats_add_aux(&parent->stats, &bfqg->stats);
-+	bfqg_stats_reset(&bfqg->stats);
-+}
-+
-+static void bfq_init_entity(struct bfq_entity *entity,
-+			    struct bfq_group *bfqg)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+
-+	entity->weight = entity->new_weight;
-+	entity->orig_weight = entity->new_weight;
-+	if (bfqq) {
-+		bfqq->ioprio = bfqq->new_ioprio;
-+		bfqq->ioprio_class = bfqq->new_ioprio_class;
-+		bfqg_get(bfqg);
-+	}
-+	entity->parent = bfqg->my_entity; /* NULL for root group */
-+	entity->sched_data = &bfqg->sched_data;
-+}
-+
-+static void bfqg_stats_exit(struct bfqg_stats *stats)
-+{
-+	blkg_rwstat_exit(&stats->merged);
-+	blkg_rwstat_exit(&stats->service_time);
-+	blkg_rwstat_exit(&stats->wait_time);
-+	blkg_rwstat_exit(&stats->queued);
-+	blkg_stat_exit(&stats->time);
-+	blkg_stat_exit(&stats->avg_queue_size_sum);
-+	blkg_stat_exit(&stats->avg_queue_size_samples);
-+	blkg_stat_exit(&stats->dequeue);
-+	blkg_stat_exit(&stats->group_wait_time);
-+	blkg_stat_exit(&stats->idle_time);
-+	blkg_stat_exit(&stats->empty_time);
-+}
-+
-+static int bfqg_stats_init(struct bfqg_stats *stats, gfp_t gfp)
-+{
-+	if (blkg_rwstat_init(&stats->merged, gfp) ||
-+	    blkg_rwstat_init(&stats->service_time, gfp) ||
-+	    blkg_rwstat_init(&stats->wait_time, gfp) ||
-+	    blkg_rwstat_init(&stats->queued, gfp) ||
-+	    blkg_stat_init(&stats->time, gfp) ||
-+	    blkg_stat_init(&stats->avg_queue_size_sum, gfp) ||
-+	    blkg_stat_init(&stats->avg_queue_size_samples, gfp) ||
-+	    blkg_stat_init(&stats->dequeue, gfp) ||
-+	    blkg_stat_init(&stats->group_wait_time, gfp) ||
-+	    blkg_stat_init(&stats->idle_time, gfp) ||
-+	    blkg_stat_init(&stats->empty_time, gfp)) {
-+		bfqg_stats_exit(stats);
-+		return -ENOMEM;
-+	}
-+
-+	return 0;
-+}
-+
-+static struct bfq_group_data *cpd_to_bfqgd(struct blkcg_policy_data *cpd)
-+{
-+	return cpd ? container_of(cpd, struct bfq_group_data, pd) : NULL;
-+}
-+
-+static struct bfq_group_data *blkcg_to_bfqgd(struct blkcg *blkcg)
-+{
-+	return cpd_to_bfqgd(blkcg_to_cpd(blkcg, &blkcg_policy_bfq));
-+}
-+
-+static struct blkcg_policy_data *bfq_cpd_alloc(gfp_t gfp)
-+{
-+	struct bfq_group_data *bgd;
-+
-+	bgd = kzalloc(sizeof(*bgd), gfp);
-+	if (!bgd)
-+		return NULL;
-+	return &bgd->pd;
-+}
-+
-+static void bfq_cpd_init(struct blkcg_policy_data *cpd)
-+{
-+	struct bfq_group_data *d = cpd_to_bfqgd(cpd);
-+
-+	d->weight = cgroup_subsys_on_dfl(io_cgrp_subsys) ?
-+		CGROUP_WEIGHT_DFL : BFQ_WEIGHT_LEGACY_DFL;
-+}
-+
-+static void bfq_cpd_free(struct blkcg_policy_data *cpd)
-+{
-+	kfree(cpd_to_bfqgd(cpd));
-+}
-+
-+static struct blkg_policy_data *bfq_pd_alloc(gfp_t gfp, int node)
-+{
-+	struct bfq_group *bfqg;
-+
-+	bfqg = kzalloc_node(sizeof(*bfqg), gfp, node);
-+	if (!bfqg)
-+		return NULL;
-+
-+	if (bfqg_stats_init(&bfqg->stats, gfp)) {
-+		kfree(bfqg);
-+		return NULL;
-+	}
-+
-+	return &bfqg->pd;
-+}
-+
-+static void bfq_pd_init(struct blkg_policy_data *pd)
-+{
-+	struct blkcg_gq *blkg;
-+	struct bfq_group *bfqg;
-+	struct bfq_data *bfqd;
-+	struct bfq_entity *entity;
-+	struct bfq_group_data *d;
-+
-+	blkg = pd_to_blkg(pd);
-+	BUG_ON(!blkg);
-+	bfqg = blkg_to_bfqg(blkg);
-+	bfqd = blkg->q->elevator->elevator_data;
-+	entity = &bfqg->entity;
-+	d = blkcg_to_bfqgd(blkg->blkcg);
-+
-+	entity->orig_weight = entity->weight = entity->new_weight = d->weight;
-+	entity->my_sched_data = &bfqg->sched_data;
-+	bfqg->my_entity = entity; /*
-+				   * the root_group's will be set to NULL
-+				   * in bfq_init_queue()
-+				   */
-+	bfqg->bfqd = bfqd;
-+	bfqg->active_entities = 0;
-+	bfqg->rq_pos_tree = RB_ROOT;
-+}
-+
-+static void bfq_pd_free(struct blkg_policy_data *pd)
-+{
-+	struct bfq_group *bfqg = pd_to_bfqg(pd);
-+
-+	bfqg_stats_exit(&bfqg->stats);
-+	return kfree(bfqg);
-+}
-+
-+static void bfq_pd_reset_stats(struct blkg_policy_data *pd)
-+{
-+	struct bfq_group *bfqg = pd_to_bfqg(pd);
-+
-+	bfqg_stats_reset(&bfqg->stats);
-+}
-+
-+static void bfq_group_set_parent(struct bfq_group *bfqg,
-+					struct bfq_group *parent)
-+{
-+	struct bfq_entity *entity;
-+
-+	BUG_ON(!parent);
-+	BUG_ON(!bfqg);
-+	BUG_ON(bfqg == parent);
-+
-+	entity = &bfqg->entity;
-+	entity->parent = parent->my_entity;
-+	entity->sched_data = &parent->sched_data;
-+}
-+
-+static struct bfq_group *bfq_lookup_bfqg(struct bfq_data *bfqd,
-+					 struct blkcg *blkcg)
-+{
-+	struct blkcg_gq *blkg;
-+
-+	blkg = blkg_lookup(blkcg, bfqd->queue);
-+	if (likely(blkg))
-+		return blkg_to_bfqg(blkg);
-+	return NULL;
-+}
-+
-+static struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd,
-+					    struct blkcg *blkcg)
-+{
-+	struct bfq_group *bfqg, *parent;
-+	struct bfq_entity *entity;
-+
-+	assert_spin_locked(bfqd->queue->queue_lock);
-+
-+	bfqg = bfq_lookup_bfqg(bfqd, blkcg);
-+
-+	if (unlikely(!bfqg))
-+		return NULL;
-+
-+	/*
-+	 * Update chain of bfq_groups as we might be handling a leaf group
-+	 * which, along with some of its relatives, has not been hooked yet
-+	 * to the private hierarchy of BFQ.
-+	 */
-+	entity = &bfqg->entity;
-+	for_each_entity(entity) {
-+		bfqg = container_of(entity, struct bfq_group, entity);
-+		BUG_ON(!bfqg);
-+		if (bfqg != bfqd->root_group) {
-+			parent = bfqg_parent(bfqg);
-+			if (!parent)
-+				parent = bfqd->root_group;
-+			BUG_ON(!parent);
-+			bfq_group_set_parent(bfqg, parent);
-+		}
-+	}
-+
-+	return bfqg;
-+}
-+
-+static void bfq_pos_tree_add_move(struct bfq_data *bfqd,
-+				  struct bfq_queue *bfqq);
-+
-+static void bfq_bfqq_expire(struct bfq_data *bfqd,
-+			    struct bfq_queue *bfqq,
-+			    bool compensate,
-+			    enum bfqq_expiration reason);
-+
-+/**
-+ * bfq_bfqq_move - migrate @bfqq to @bfqg.
-+ * @bfqd: queue descriptor.
-+ * @bfqq: the queue to move.
-+ * @bfqg: the group to move to.
-+ *
-+ * Move @bfqq to @bfqg, deactivating it from its old group and reactivating
-+ * it on the new one.  Avoid putting the entity on the old group idle tree.
-+ *
-+ * Must be called under the queue lock; the cgroup owning @bfqg must
-+ * not disappear (by now this just means that we are called under
-+ * rcu_read_lock()).
-+ */
-+static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+			  struct bfq_group *bfqg)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+
-+	BUG_ON(!bfq_bfqq_busy(bfqq) && !RB_EMPTY_ROOT(&bfqq->sort_list));
-+	BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list) && !entity->on_st);
-+	BUG_ON(bfq_bfqq_busy(bfqq) && RB_EMPTY_ROOT(&bfqq->sort_list)
-+	       && entity->on_st &&
-+	       bfqq != bfqd->in_service_queue);
-+	BUG_ON(!bfq_bfqq_busy(bfqq) && bfqq == bfqd->in_service_queue);
-+
-+	/* If bfqq is empty, then bfq_bfqq_expire also invokes
-+	 * bfq_del_bfqq_busy, thereby removing bfqq and its entity
-+	 * from data structures related to current group. Otherwise we
-+	 * need to remove bfqq explicitly with bfq_deactivate_bfqq, as
-+	 * we do below.
-+	 */
-+	if (bfqq == bfqd->in_service_queue)
-+		bfq_bfqq_expire(bfqd, bfqd->in_service_queue,
-+				false, BFQ_BFQQ_PREEMPTED);
-+
-+	BUG_ON(entity->on_st && !bfq_bfqq_busy(bfqq)
-+	    && &bfq_entity_service_tree(entity)->idle !=
-+	       entity->tree);
-+
-+	BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list) && bfq_bfqq_busy(bfqq));
-+
-+	if (bfq_bfqq_busy(bfqq))
-+		bfq_deactivate_bfqq(bfqd, bfqq, false, false);
-+	else if (entity->on_st) {
-+		BUG_ON(&bfq_entity_service_tree(entity)->idle !=
-+		       entity->tree);
-+		bfq_put_idle_entity(bfq_entity_service_tree(entity), entity);
-+	}
-+	bfqg_put(bfqq_group(bfqq));
-+
-+	/*
-+	 * Here we use a reference to bfqg.  We don't need a refcounter
-+	 * as the cgroup reference will not be dropped, so that its
-+	 * destroy() callback will not be invoked.
-+	 */
-+	entity->parent = bfqg->my_entity;
-+	entity->sched_data = &bfqg->sched_data;
-+	bfqg_get(bfqg);
-+
-+	BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list) && bfq_bfqq_busy(bfqq));
-+	if (bfq_bfqq_busy(bfqq)) {
-+		bfq_pos_tree_add_move(bfqd, bfqq);
-+		bfq_activate_bfqq(bfqd, bfqq);
-+	}
-+
-+	if (!bfqd->in_service_queue && !bfqd->rq_in_driver)
-+		bfq_schedule_dispatch(bfqd);
-+	BUG_ON(entity->on_st && !bfq_bfqq_busy(bfqq)
-+	       && &bfq_entity_service_tree(entity)->idle !=
-+	       entity->tree);
-+}
-+
-+/**
-+ * __bfq_bic_change_cgroup - move @bic to @cgroup.
-+ * @bfqd: the queue descriptor.
-+ * @bic: the bic to move.
-+ * @blkcg: the blk-cgroup to move to.
-+ *
-+ * Move bic to blkcg, assuming that bfqd->queue is locked; the caller
-+ * has to make sure that the reference to cgroup is valid across the call.
-+ *
-+ * NOTE: an alternative approach might have been to store the current
-+ * cgroup in bfqq and getting a reference to it, reducing the lookup
-+ * time here, at the price of slightly more complex code.
-+ */
-+static struct bfq_group *__bfq_bic_change_cgroup(struct bfq_data *bfqd,
-+						struct bfq_io_cq *bic,
-+						struct blkcg *blkcg)
-+{
-+	struct bfq_queue *async_bfqq = bic_to_bfqq(bic, 0);
-+	struct bfq_queue *sync_bfqq = bic_to_bfqq(bic, 1);
-+	struct bfq_group *bfqg;
-+	struct bfq_entity *entity;
-+
-+	lockdep_assert_held(bfqd->queue->queue_lock);
-+
-+	bfqg = bfq_find_set_group(bfqd, blkcg);
-+
-+	if (unlikely(!bfqg))
-+		bfqg = bfqd->root_group;
-+
-+	if (async_bfqq) {
-+		entity = &async_bfqq->entity;
-+
-+		if (entity->sched_data != &bfqg->sched_data) {
-+			bic_set_bfqq(bic, NULL, 0);
-+			bfq_log_bfqq(bfqd, async_bfqq,
-+				     "bic_change_group: %p %d",
-+				     async_bfqq,
-+				     async_bfqq->ref);
-+			bfq_put_queue(async_bfqq);
-+		}
-+	}
-+
-+	if (sync_bfqq) {
-+		entity = &sync_bfqq->entity;
-+		if (entity->sched_data != &bfqg->sched_data)
-+			bfq_bfqq_move(bfqd, sync_bfqq, bfqg);
-+	}
-+
-+	return bfqg;
-+}
-+
-+static void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio)
-+{
-+	struct bfq_data *bfqd = bic_to_bfqd(bic);
-+	struct bfq_group *bfqg = NULL;
-+	uint64_t serial_nr;
-+
-+	rcu_read_lock();
-+	serial_nr = bio_blkcg(bio)->css.serial_nr;
-+
-+	/*
-+	 * Check whether blkcg has changed.  The condition may trigger
-+	 * spuriously on a newly created cic but there's no harm.
-+	 */
-+	if (unlikely(!bfqd) || likely(bic->blkcg_serial_nr == serial_nr))
-+		goto out;
-+
-+	bfqg = __bfq_bic_change_cgroup(bfqd, bic, bio_blkcg(bio));
-+	bic->blkcg_serial_nr = serial_nr;
-+out:
-+	rcu_read_unlock();
-+}
-+
-+/**
-+ * bfq_flush_idle_tree - deactivate any entity on the idle tree of @st.
-+ * @st: the service tree being flushed.
-+ */
-+static void bfq_flush_idle_tree(struct bfq_service_tree *st)
-+{
-+	struct bfq_entity *entity = st->first_idle;
-+
-+	for (; entity ; entity = st->first_idle)
-+		__bfq_deactivate_entity(entity, false);
-+}
-+
-+/**
-+ * bfq_reparent_leaf_entity - move leaf entity to the root_group.
-+ * @bfqd: the device data structure with the root group.
-+ * @entity: the entity to move.
-+ */
-+static void bfq_reparent_leaf_entity(struct bfq_data *bfqd,
-+				     struct bfq_entity *entity)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+
-+	BUG_ON(!bfqq);
-+	bfq_bfqq_move(bfqd, bfqq, bfqd->root_group);
-+}
-+
-+/**
-+ * bfq_reparent_active_entities - move to the root group all active
-+ *                                entities.
-+ * @bfqd: the device data structure with the root group.
-+ * @bfqg: the group to move from.
-+ * @st: the service tree with the entities.
-+ *
-+ * Needs queue_lock to be taken and reference to be valid over the call.
-+ */
-+static void bfq_reparent_active_entities(struct bfq_data *bfqd,
-+					 struct bfq_group *bfqg,
-+					 struct bfq_service_tree *st)
-+{
-+	struct rb_root *active = &st->active;
-+	struct bfq_entity *entity = NULL;
-+
-+	if (!RB_EMPTY_ROOT(&st->active))
-+		entity = bfq_entity_of(rb_first(active));
-+
-+	for (; entity ; entity = bfq_entity_of(rb_first(active)))
-+		bfq_reparent_leaf_entity(bfqd, entity);
-+
-+	if (bfqg->sched_data.in_service_entity)
-+		bfq_reparent_leaf_entity(bfqd,
-+			bfqg->sched_data.in_service_entity);
-+}
-+
-+/**
-+ * bfq_pd_offline - deactivate the entity associated with @pd,
-+ *		    and reparent its children entities.
-+ * @pd: descriptor of the policy going offline.
-+ *
-+ * blkio already grabs the queue_lock for us, so no need to use
-+ * RCU-based magic
-+ */
-+static void bfq_pd_offline(struct blkg_policy_data *pd)
-+{
-+	struct bfq_service_tree *st;
-+	struct bfq_group *bfqg;
-+	struct bfq_data *bfqd;
-+	struct bfq_entity *entity;
-+	int i;
-+
-+	BUG_ON(!pd);
-+	bfqg = pd_to_bfqg(pd);
-+	BUG_ON(!bfqg);
-+	bfqd = bfqg->bfqd;
-+	BUG_ON(bfqd && !bfqd->root_group);
-+
-+	entity = bfqg->my_entity;
-+
-+	if (!entity) /* root group */
-+		return;
-+
-+	/*
-+	 * Empty all service_trees belonging to this group before
-+	 * deactivating the group itself.
-+	 */
-+	for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) {
-+		BUG_ON(!bfqg->sched_data.service_tree);
-+		st = bfqg->sched_data.service_tree + i;
-+		/*
-+		 * The idle tree may still contain bfq_queues belonging
-+		 * to exited task because they never migrated to a different
-+		 * cgroup from the one being destroyed now.  No one else
-+		 * can access them so it's safe to act without any lock.
-+		 */
-+		bfq_flush_idle_tree(st);
-+
-+		/*
-+		 * It may happen that some queues are still active
-+		 * (busy) upon group destruction (if the corresponding
-+		 * processes have been forced to terminate). We move
-+		 * all the leaf entities corresponding to these queues
-+		 * to the root_group.
-+		 * Also, it may happen that the group has an entity
-+		 * in service, which is disconnected from the active
-+		 * tree: it must be moved, too.
-+		 * There is no need to put the sync queues, as the
-+		 * scheduler has taken no reference.
-+		 */
-+		bfq_reparent_active_entities(bfqd, bfqg, st);
-+		BUG_ON(!RB_EMPTY_ROOT(&st->active));
-+		BUG_ON(!RB_EMPTY_ROOT(&st->idle));
-+	}
-+	BUG_ON(bfqg->sched_data.next_in_service);
-+	BUG_ON(bfqg->sched_data.in_service_entity);
-+
-+	__bfq_deactivate_entity(entity, false);
-+	bfq_put_async_queues(bfqd, bfqg);
-+
-+	/*
-+	 * @blkg is going offline and will be ignored by
-+	 * blkg_[rw]stat_recursive_sum().  Transfer stats to the parent so
-+	 * that they don't get lost.  If IOs complete after this point, the
-+	 * stats for them will be lost.  Oh well...
-+	 */
-+	bfqg_stats_xfer_dead(bfqg);
-+}
-+
-+static void bfq_end_wr_async(struct bfq_data *bfqd)
-+{
-+	struct blkcg_gq *blkg;
-+
-+	list_for_each_entry(blkg, &bfqd->queue->blkg_list, q_node) {
-+		struct bfq_group *bfqg = blkg_to_bfqg(blkg);
-+		BUG_ON(!bfqg);
-+
-+		bfq_end_wr_async_queues(bfqd, bfqg);
-+	}
-+	bfq_end_wr_async_queues(bfqd, bfqd->root_group);
-+}
-+
-+static int bfq_io_show_weight(struct seq_file *sf, void *v)
-+{
-+	struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
-+	struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg);
-+	unsigned int val = 0;
-+
-+	if (bfqgd)
-+		val = bfqgd->weight;
-+
-+	seq_printf(sf, "%u\n", val);
-+
-+	return 0;
-+}
-+
-+static int bfq_io_set_weight_legacy(struct cgroup_subsys_state *css,
-+				    struct cftype *cftype,
-+				    u64 val)
-+{
-+	struct blkcg *blkcg = css_to_blkcg(css);
-+	struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg);
-+	struct blkcg_gq *blkg;
-+	int ret = -ERANGE;
-+
-+	if (val < BFQ_MIN_WEIGHT || val > BFQ_MAX_WEIGHT)
-+		return ret;
-+
-+	ret = 0;
-+	spin_lock_irq(&blkcg->lock);
-+	bfqgd->weight = (unsigned short)val;
-+	hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
-+		struct bfq_group *bfqg = blkg_to_bfqg(blkg);
-+
-+		if (!bfqg)
-+			continue;
-+		/*
-+		 * Setting the prio_changed flag of the entity
-+		 * to 1 with new_weight == weight would re-set
-+		 * the value of the weight to its ioprio mapping.
-+		 * Set the flag only if necessary.
-+		 */
-+		if ((unsigned short)val != bfqg->entity.new_weight) {
-+			bfqg->entity.new_weight = (unsigned short)val;
-+			/*
-+			 * Make sure that the above new value has been
-+			 * stored in bfqg->entity.new_weight before
-+			 * setting the prio_changed flag. In fact,
-+			 * this flag may be read asynchronously (in
-+			 * critical sections protected by a different
-+			 * lock than that held here), and finding this
-+			 * flag set may cause the execution of the code
-+			 * for updating parameters whose value may
-+			 * depend also on bfqg->entity.new_weight (in
-+			 * __bfq_entity_update_weight_prio).
-+			 * This barrier makes sure that the new value
-+			 * of bfqg->entity.new_weight is correctly
-+			 * seen in that code.
-+			 */
-+			smp_wmb();
-+			bfqg->entity.prio_changed = 1;
-+		}
-+	}
-+	spin_unlock_irq(&blkcg->lock);
-+
-+	return ret;
-+}
-+
-+static ssize_t bfq_io_set_weight(struct kernfs_open_file *of,
-+				 char *buf, size_t nbytes,
-+				 loff_t off)
-+{
-+	u64 weight;
-+	/* First unsigned long found in the file is used */
-+	int ret = kstrtoull(strim(buf), 0, &weight);
-+
-+	if (ret)
-+		return ret;
-+
-+	return bfq_io_set_weight_legacy(of_css(of), NULL, weight);
-+}
-+
-+static int bfqg_print_stat(struct seq_file *sf, void *v)
-+{
-+	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_stat,
-+			  &blkcg_policy_bfq, seq_cft(sf)->private, false);
-+	return 0;
-+}
-+
-+static int bfqg_print_rwstat(struct seq_file *sf, void *v)
-+{
-+	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_rwstat,
-+			  &blkcg_policy_bfq, seq_cft(sf)->private, true);
-+	return 0;
-+}
-+
-+static u64 bfqg_prfill_stat_recursive(struct seq_file *sf,
-+				      struct blkg_policy_data *pd, int off)
-+{
-+	u64 sum = blkg_stat_recursive_sum(pd_to_blkg(pd),
-+					  &blkcg_policy_bfq, off);
-+	return __blkg_prfill_u64(sf, pd, sum);
-+}
-+
-+static u64 bfqg_prfill_rwstat_recursive(struct seq_file *sf,
-+					struct blkg_policy_data *pd, int off)
-+{
-+	struct blkg_rwstat sum = blkg_rwstat_recursive_sum(pd_to_blkg(pd),
-+							   &blkcg_policy_bfq,
-+							   off);
-+	return __blkg_prfill_rwstat(sf, pd, &sum);
-+}
-+
-+static int bfqg_print_stat_recursive(struct seq_file *sf, void *v)
-+{
-+	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
-+			  bfqg_prfill_stat_recursive, &blkcg_policy_bfq,
-+			  seq_cft(sf)->private, false);
-+	return 0;
-+}
-+
-+static int bfqg_print_rwstat_recursive(struct seq_file *sf, void *v)
-+{
-+	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
-+			  bfqg_prfill_rwstat_recursive, &blkcg_policy_bfq,
-+			  seq_cft(sf)->private, true);
-+	return 0;
-+}
-+
-+static u64 bfqg_prfill_sectors(struct seq_file *sf, struct blkg_policy_data *pd,
-+			       int off)
-+{
-+	u64 sum = blkg_rwstat_total(&pd->blkg->stat_bytes);
-+
-+	return __blkg_prfill_u64(sf, pd, sum >> 9);
-+}
-+
-+static int bfqg_print_stat_sectors(struct seq_file *sf, void *v)
-+{
-+	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
-+			  bfqg_prfill_sectors, &blkcg_policy_bfq, 0, false);
-+	return 0;
-+}
-+
-+static u64 bfqg_prfill_sectors_recursive(struct seq_file *sf,
-+					 struct blkg_policy_data *pd, int off)
-+{
-+	struct blkg_rwstat tmp = blkg_rwstat_recursive_sum(pd->blkg, NULL,
-+					offsetof(struct blkcg_gq, stat_bytes));
-+	u64 sum = atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_READ]) +
-+		atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_WRITE]);
-+
-+	return __blkg_prfill_u64(sf, pd, sum >> 9);
-+}
-+
-+static int bfqg_print_stat_sectors_recursive(struct seq_file *sf, void *v)
-+{
-+	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
-+			  bfqg_prfill_sectors_recursive, &blkcg_policy_bfq, 0,
-+			  false);
-+	return 0;
-+}
-+
-+
-+static u64 bfqg_prfill_avg_queue_size(struct seq_file *sf,
-+				      struct blkg_policy_data *pd, int off)
-+{
-+	struct bfq_group *bfqg = pd_to_bfqg(pd);
-+	u64 samples = blkg_stat_read(&bfqg->stats.avg_queue_size_samples);
-+	u64 v = 0;
-+
-+	if (samples) {
-+		v = blkg_stat_read(&bfqg->stats.avg_queue_size_sum);
-+		v = div64_u64(v, samples);
-+	}
-+	__blkg_prfill_u64(sf, pd, v);
-+	return 0;
-+}
-+
-+/* print avg_queue_size */
-+static int bfqg_print_avg_queue_size(struct seq_file *sf, void *v)
-+{
-+	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
-+			  bfqg_prfill_avg_queue_size, &blkcg_policy_bfq,
-+			  0, false);
-+	return 0;
-+}
-+
-+static struct bfq_group *
-+bfq_create_group_hierarchy(struct bfq_data *bfqd, int node)
-+{
-+	int ret;
-+
-+	ret = blkcg_activate_policy(bfqd->queue, &blkcg_policy_bfq);
-+	if (ret)
-+		return NULL;
-+
-+	return blkg_to_bfqg(bfqd->queue->root_blkg);
-+}
-+
-+static struct cftype bfq_blkcg_legacy_files[] = {
-+	{
-+		.name = "bfq.weight",
-+		.flags = CFTYPE_NOT_ON_ROOT,
-+		.seq_show = bfq_io_show_weight,
-+		.write_u64 = bfq_io_set_weight_legacy,
-+	},
-+
-+	/* statistics, covers only the tasks in the bfqg */
-+	{
-+		.name = "bfq.time",
-+		.private = offsetof(struct bfq_group, stats.time),
-+		.seq_show = bfqg_print_stat,
-+	},
-+	{
-+		.name = "bfq.sectors",
-+		.seq_show = bfqg_print_stat_sectors,
-+	},
-+	{
-+		.name = "bfq.io_service_bytes",
-+		.private = (unsigned long)&blkcg_policy_bfq,
-+		.seq_show = blkg_print_stat_bytes,
-+	},
-+	{
-+		.name = "bfq.io_serviced",
-+		.private = (unsigned long)&blkcg_policy_bfq,
-+		.seq_show = blkg_print_stat_ios,
-+	},
-+	{
-+		.name = "bfq.io_service_time",
-+		.private = offsetof(struct bfq_group, stats.service_time),
-+		.seq_show = bfqg_print_rwstat,
-+	},
-+	{
-+		.name = "bfq.io_wait_time",
-+		.private = offsetof(struct bfq_group, stats.wait_time),
-+		.seq_show = bfqg_print_rwstat,
-+	},
-+	{
-+		.name = "bfq.io_merged",
-+		.private = offsetof(struct bfq_group, stats.merged),
-+		.seq_show = bfqg_print_rwstat,
-+	},
-+	{
-+		.name = "bfq.io_queued",
-+		.private = offsetof(struct bfq_group, stats.queued),
-+		.seq_show = bfqg_print_rwstat,
-+	},
-+
-+	/* the same statictics which cover the bfqg and its descendants */
-+	{
-+		.name = "bfq.time_recursive",
-+		.private = offsetof(struct bfq_group, stats.time),
-+		.seq_show = bfqg_print_stat_recursive,
-+	},
-+	{
-+		.name = "bfq.sectors_recursive",
-+		.seq_show = bfqg_print_stat_sectors_recursive,
-+	},
-+	{
-+		.name = "bfq.io_service_bytes_recursive",
-+		.private = (unsigned long)&blkcg_policy_bfq,
-+		.seq_show = blkg_print_stat_bytes_recursive,
-+	},
-+	{
-+		.name = "bfq.io_serviced_recursive",
-+		.private = (unsigned long)&blkcg_policy_bfq,
-+		.seq_show = blkg_print_stat_ios_recursive,
-+	},
-+	{
-+		.name = "bfq.io_service_time_recursive",
-+		.private = offsetof(struct bfq_group, stats.service_time),
-+		.seq_show = bfqg_print_rwstat_recursive,
-+	},
-+	{
-+		.name = "bfq.io_wait_time_recursive",
-+		.private = offsetof(struct bfq_group, stats.wait_time),
-+		.seq_show = bfqg_print_rwstat_recursive,
-+	},
-+	{
-+		.name = "bfq.io_merged_recursive",
-+		.private = offsetof(struct bfq_group, stats.merged),
-+		.seq_show = bfqg_print_rwstat_recursive,
-+	},
-+	{
-+		.name = "bfq.io_queued_recursive",
-+		.private = offsetof(struct bfq_group, stats.queued),
-+		.seq_show = bfqg_print_rwstat_recursive,
-+	},
-+	{
-+		.name = "bfq.avg_queue_size",
-+		.seq_show = bfqg_print_avg_queue_size,
-+	},
-+	{
-+		.name = "bfq.group_wait_time",
-+		.private = offsetof(struct bfq_group, stats.group_wait_time),
-+		.seq_show = bfqg_print_stat,
-+	},
-+	{
-+		.name = "bfq.idle_time",
-+		.private = offsetof(struct bfq_group, stats.idle_time),
-+		.seq_show = bfqg_print_stat,
-+	},
-+	{
-+		.name = "bfq.empty_time",
-+		.private = offsetof(struct bfq_group, stats.empty_time),
-+		.seq_show = bfqg_print_stat,
-+	},
-+	{
-+		.name = "bfq.dequeue",
-+		.private = offsetof(struct bfq_group, stats.dequeue),
-+		.seq_show = bfqg_print_stat,
-+	},
-+	{ }	/* terminate */
-+};
-+
-+static struct cftype bfq_blkg_files[] = {
-+	{
-+		.name = "bfq.weight",
-+		.flags = CFTYPE_NOT_ON_ROOT,
-+		.seq_show = bfq_io_show_weight,
-+		.write = bfq_io_set_weight,
-+	},
-+	{} /* terminate */
-+};
-+
-+#else /* CONFIG_BFQ_SQ_GROUP_IOSCHED */
-+
-+static inline void bfqg_stats_update_io_add(struct bfq_group *bfqg,
-+			struct bfq_queue *bfqq, unsigned int op) { }
-+static inline void
-+bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op) { }
-+static inline void
-+bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op) { }
-+static inline void bfqg_stats_update_completion(struct bfq_group *bfqg,
-+			uint64_t start_time, uint64_t io_start_time,
-+			unsigned int op) { }
-+static inline void
-+bfqg_stats_set_start_group_wait_time(struct bfq_group *bfqg,
-+				     struct bfq_group *curr_bfqg) { }
-+static inline void bfqg_stats_end_empty_time(struct bfqg_stats *stats) { }
-+static inline void bfqg_stats_update_dequeue(struct bfq_group *bfqg) { }
-+static inline void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg) { }
-+static inline void bfqg_stats_update_idle_time(struct bfq_group *bfqg) { }
-+static inline void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg) { }
-+static inline void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg) { }
-+
-+static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+			  struct bfq_group *bfqg) {}
-+
-+static void bfq_init_entity(struct bfq_entity *entity,
-+			    struct bfq_group *bfqg)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+
-+	entity->weight = entity->new_weight;
-+	entity->orig_weight = entity->new_weight;
-+	if (bfqq) {
-+		bfqq->ioprio = bfqq->new_ioprio;
-+		bfqq->ioprio_class = bfqq->new_ioprio_class;
-+	}
-+	entity->sched_data = &bfqg->sched_data;
-+}
-+
-+static void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio) {}
-+
-+static void bfq_end_wr_async(struct bfq_data *bfqd)
-+{
-+	bfq_end_wr_async_queues(bfqd, bfqd->root_group);
-+}
-+
-+static struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd,
-+					    struct blkcg *blkcg)
-+{
-+	return bfqd->root_group;
-+}
-+
-+static struct bfq_group *bfqq_group(struct bfq_queue *bfqq)
-+{
-+	return bfqq->bfqd->root_group;
-+}
-+
-+static struct bfq_group *
-+bfq_create_group_hierarchy(struct bfq_data *bfqd, int node)
-+{
-+	struct bfq_group *bfqg;
-+	int i;
-+
-+	bfqg = kmalloc_node(sizeof(*bfqg), GFP_KERNEL | __GFP_ZERO, node);
-+	if (!bfqg)
-+		return NULL;
-+
-+	for (i = 0; i < BFQ_IOPRIO_CLASSES; i++)
-+		bfqg->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT;
-+
-+	return bfqg;
-+}
-+#endif
-diff --git a/block/bfq-ioc.c b/block/bfq-ioc.c
-new file mode 100644
-index 000000000000..fb7bb8f08b75
---- /dev/null
-+++ b/block/bfq-ioc.c
-@@ -0,0 +1,36 @@
-+/*
-+ * BFQ: I/O context handling.
-+ *
-+ * Based on ideas and code from CFQ:
-+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
-+ *
-+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
-+ *		      Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2010 Paolo Valente <paolo.valente@unimore.it>
-+ */
-+
-+/**
-+ * icq_to_bic - convert iocontext queue structure to bfq_io_cq.
-+ * @icq: the iocontext queue.
-+ */
-+static struct bfq_io_cq *icq_to_bic(struct io_cq *icq)
-+{
-+	/* bic->icq is the first member, %NULL will convert to %NULL */
-+	return container_of(icq, struct bfq_io_cq, icq);
-+}
-+
-+/**
-+ * bfq_bic_lookup - search into @ioc a bic associated to @bfqd.
-+ * @bfqd: the lookup key.
-+ * @ioc: the io_context of the process doing I/O.
-+ *
-+ * Queue lock must be held.
-+ */
-+static struct bfq_io_cq *bfq_bic_lookup(struct bfq_data *bfqd,
-+					struct io_context *ioc)
-+{
-+	if (ioc)
-+		return icq_to_bic(ioc_lookup_icq(ioc, bfqd->queue));
-+	return NULL;
-+}
-diff --git a/block/bfq-sched.c b/block/bfq-sched.c
-new file mode 100644
-index 000000000000..ac8991bca9fa
---- /dev/null
-+++ b/block/bfq-sched.c
-@@ -0,0 +1,2002 @@
-+/*
-+ * BFQ: Hierarchical B-WF2Q+ scheduler.
-+ *
-+ * Based on ideas and code from CFQ:
-+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
-+ *
-+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
-+ *		      Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2016 Paolo Valente <paolo.valente@linaro.org>
-+ */
-+
-+static struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
-+
-+/**
-+ * bfq_gt - compare two timestamps.
-+ * @a: first ts.
-+ * @b: second ts.
-+ *
-+ * Return @a > @b, dealing with wrapping correctly.
-+ */
-+static int bfq_gt(u64 a, u64 b)
-+{
-+	return (s64)(a - b) > 0;
-+}
-+
-+static struct bfq_entity *bfq_root_active_entity(struct rb_root *tree)
-+{
-+	struct rb_node *node = tree->rb_node;
-+
-+	return rb_entry(node, struct bfq_entity, rb_node);
-+}
-+
-+static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd);
-+
-+static bool bfq_update_parent_budget(struct bfq_entity *next_in_service);
-+
-+/**
-+ * bfq_update_next_in_service - update sd->next_in_service
-+ * @sd: sched_data for which to perform the update.
-+ * @new_entity: if not NULL, pointer to the entity whose activation,
-+ *		requeueing or repositionig triggered the invocation of
-+ *		this function.
-+ *
-+ * This function is called to update sd->next_in_service, which, in
-+ * its turn, may change as a consequence of the insertion or
-+ * extraction of an entity into/from one of the active trees of
-+ * sd. These insertions/extractions occur as a consequence of
-+ * activations/deactivations of entities, with some activations being
-+ * 'true' activations, and other activations being requeueings (i.e.,
-+ * implementing the second, requeueing phase of the mechanism used to
-+ * reposition an entity in its active tree; see comments on
-+ * __bfq_activate_entity and __bfq_requeue_entity for details). In
-+ * both the last two activation sub-cases, new_entity points to the
-+ * just activated or requeued entity.
-+ *
-+ * Returns true if sd->next_in_service changes in such a way that
-+ * entity->parent may become the next_in_service for its parent
-+ * entity.
-+ */
-+static bool bfq_update_next_in_service(struct bfq_sched_data *sd,
-+				       struct bfq_entity *new_entity)
-+{
-+	struct bfq_entity *next_in_service = sd->next_in_service;
-+	struct bfq_queue *bfqq;
-+	bool parent_sched_may_change = false;
-+
-+	/*
-+	 * If this update is triggered by the activation, requeueing
-+	 * or repositiong of an entity that does not coincide with
-+	 * sd->next_in_service, then a full lookup in the active tree
-+	 * can be avoided. In fact, it is enough to check whether the
-+	 * just-modified entity has a higher priority than
-+	 * sd->next_in_service, or, even if it has the same priority
-+	 * as sd->next_in_service, is eligible and has a lower virtual
-+	 * finish time than sd->next_in_service. If this compound
-+	 * condition holds, then the new entity becomes the new
-+	 * next_in_service. Otherwise no change is needed.
-+	 */
-+	if (new_entity && new_entity != sd->next_in_service) {
-+		/*
-+		 * Flag used to decide whether to replace
-+		 * sd->next_in_service with new_entity. Tentatively
-+		 * set to true, and left as true if
-+		 * sd->next_in_service is NULL.
-+		 */
-+		bool replace_next = true;
-+
-+		/*
-+		 * If there is already a next_in_service candidate
-+		 * entity, then compare class priorities or timestamps
-+		 * to decide whether to replace sd->service_tree with
-+		 * new_entity.
-+		 */
-+		if (next_in_service) {
-+			unsigned int new_entity_class_idx =
-+				bfq_class_idx(new_entity);
-+			struct bfq_service_tree *st =
-+				sd->service_tree + new_entity_class_idx;
-+
-+			/*
-+			 * For efficiency, evaluate the most likely
-+			 * sub-condition first.
-+			 */
-+			replace_next =
-+				(new_entity_class_idx ==
-+				 bfq_class_idx(next_in_service)
-+				 &&
-+				 !bfq_gt(new_entity->start, st->vtime)
-+				 &&
-+				 bfq_gt(next_in_service->finish,
-+					new_entity->finish))
-+				||
-+				new_entity_class_idx <
-+				bfq_class_idx(next_in_service);
-+		}
-+
-+		if (replace_next)
-+			next_in_service = new_entity;
-+	} else /* invoked because of a deactivation: lookup needed */
-+		next_in_service = bfq_lookup_next_entity(sd);
-+
-+	if (next_in_service) {
-+		parent_sched_may_change = !sd->next_in_service ||
-+			bfq_update_parent_budget(next_in_service);
-+	}
-+
-+	sd->next_in_service = next_in_service;
-+
-+	if (!next_in_service)
-+		return parent_sched_may_change;
-+
-+	bfqq = bfq_entity_to_bfqq(next_in_service);
-+	if (bfqq)
-+		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			     "update_next_in_service: chosen this queue");
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	else {
-+		struct bfq_group *bfqg =
-+			container_of(next_in_service,
-+				     struct bfq_group, entity);
-+
-+		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+			     "update_next_in_service: chosen this entity");
-+	}
-+#endif
-+	return parent_sched_may_change;
-+}
-+
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+/* both next loops stop at one of the child entities of the root group */
-+#define for_each_entity(entity)				\
-+	for (; entity ; entity = entity->parent)
-+
-+/*
-+ * For each iteration, compute parent in advance, so as to be safe if
-+ * entity is deallocated during the iteration. Such a deallocation may
-+ * happen as a consequence of a bfq_put_queue that frees the bfq_queue
-+ * containing entity.
-+ */
-+#define for_each_entity_safe(entity, parent)				\
-+	for (; entity && ({ parent = entity->parent; 1; }); entity = parent)
-+
-+/*
-+ * Returns true if this budget changes may let next_in_service->parent
-+ * become the next_in_service entity for its parent entity.
-+ */
-+static bool bfq_update_parent_budget(struct bfq_entity *next_in_service)
-+{
-+	struct bfq_entity *bfqg_entity;
-+	struct bfq_group *bfqg;
-+	struct bfq_sched_data *group_sd;
-+	bool ret = false;
-+
-+	BUG_ON(!next_in_service);
-+
-+	group_sd = next_in_service->sched_data;
-+
-+	bfqg = container_of(group_sd, struct bfq_group, sched_data);
-+	/*
-+	 * bfq_group's my_entity field is not NULL only if the group
-+	 * is not the root group. We must not touch the root entity
-+	 * as it must never become an in-service entity.
-+	 */
-+	bfqg_entity = bfqg->my_entity;
-+	if (bfqg_entity) {
-+		if (bfqg_entity->budget > next_in_service->budget)
-+			ret = true;
-+		bfqg_entity->budget = next_in_service->budget;
-+	}
-+
-+	return ret;
-+}
-+
-+/*
-+ * This function tells whether entity stops being a candidate for next
-+ * service, according to the following logic.
-+ *
-+ * This function is invoked for an entity that is about to be set in
-+ * service. If such an entity is a queue, then the entity is no longer
-+ * a candidate for next service (i.e, a candidate entity to serve
-+ * after the in-service entity is expired). The function then returns
-+ * true.
-+ *
-+ * In contrast, the entity could stil be a candidate for next service
-+ * if it is not a queue, and has more than one child. In fact, even if
-+ * one of its children is about to be set in service, other children
-+ * may still be the next to serve. As a consequence, a non-queue
-+ * entity is not a candidate for next-service only if it has only one
-+ * child. And only if this condition holds, then the function returns
-+ * true for a non-queue entity.
-+ */
-+static bool bfq_no_longer_next_in_service(struct bfq_entity *entity)
-+{
-+	struct bfq_group *bfqg;
-+
-+	if (bfq_entity_to_bfqq(entity))
-+		return true;
-+
-+	bfqg = container_of(entity, struct bfq_group, entity);
-+
-+	BUG_ON(bfqg == ((struct bfq_data *)(bfqg->bfqd))->root_group);
-+	BUG_ON(bfqg->active_entities == 0);
-+	if (bfqg->active_entities == 1)
-+		return true;
-+
-+	return false;
-+}
-+
-+#else /* CONFIG_BFQ_SQ_GROUP_IOSCHED */
-+#define for_each_entity(entity)	\
-+	for (; entity ; entity = NULL)
-+
-+#define for_each_entity_safe(entity, parent) \
-+	for (parent = NULL; entity ; entity = parent)
-+
-+static bool bfq_update_parent_budget(struct bfq_entity *next_in_service)
-+{
-+	return false;
-+}
-+
-+static bool bfq_no_longer_next_in_service(struct bfq_entity *entity)
-+{
-+	return true;
-+}
-+
-+#endif /* CONFIG_BFQ_SQ_GROUP_IOSCHED */
-+
-+/*
-+ * Shift for timestamp calculations.  This actually limits the maximum
-+ * service allowed in one timestamp delta (small shift values increase it),
-+ * the maximum total weight that can be used for the queues in the system
-+ * (big shift values increase it), and the period of virtual time
-+ * wraparounds.
-+ */
-+#define WFQ_SERVICE_SHIFT	22
-+
-+static struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity)
-+{
-+	struct bfq_queue *bfqq = NULL;
-+
-+	BUG_ON(!entity);
-+
-+	if (!entity->my_sched_data)
-+		bfqq = container_of(entity, struct bfq_queue, entity);
-+
-+	return bfqq;
-+}
-+
-+
-+/**
-+ * bfq_delta - map service into the virtual time domain.
-+ * @service: amount of service.
-+ * @weight: scale factor (weight of an entity or weight sum).
-+ */
-+static u64 bfq_delta(unsigned long service, unsigned long weight)
-+{
-+	u64 d = (u64)service << WFQ_SERVICE_SHIFT;
-+
-+	do_div(d, weight);
-+	return d;
-+}
-+
-+/**
-+ * bfq_calc_finish - assign the finish time to an entity.
-+ * @entity: the entity to act upon.
-+ * @service: the service to be charged to the entity.
-+ */
-+static void bfq_calc_finish(struct bfq_entity *entity, unsigned long service)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+	unsigned long long start, finish, delta;
-+
-+	BUG_ON(entity->weight == 0);
-+
-+	entity->finish = entity->start +
-+		bfq_delta(service, entity->weight);
-+
-+	start = ((entity->start>>10)*1000)>>12;
-+	finish = ((entity->finish>>10)*1000)>>12;
-+	delta = ((bfq_delta(service, entity->weight)>>10)*1000)>>12;
-+
-+	if (bfqq) {
-+		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			"calc_finish: serv %lu, w %d",
-+			service, entity->weight);
-+		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			"calc_finish: start %llu, finish %llu, delta %llu",
-+			start, finish, delta);
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	} else {
-+		struct bfq_group *bfqg =
-+			container_of(entity, struct bfq_group, entity);
-+
-+		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+			"calc_finish group: serv %lu, w %d",
-+			     service, entity->weight);
-+		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+			"calc_finish group: start %llu, finish %llu, delta %llu",
-+			start, finish, delta);
-+#endif
-+	}
-+}
-+
-+/**
-+ * bfq_entity_of - get an entity from a node.
-+ * @node: the node field of the entity.
-+ *
-+ * Convert a node pointer to the relative entity.  This is used only
-+ * to simplify the logic of some functions and not as the generic
-+ * conversion mechanism because, e.g., in the tree walking functions,
-+ * the check for a %NULL value would be redundant.
-+ */
-+static struct bfq_entity *bfq_entity_of(struct rb_node *node)
-+{
-+	struct bfq_entity *entity = NULL;
-+
-+	if (node)
-+		entity = rb_entry(node, struct bfq_entity, rb_node);
-+
-+	return entity;
-+}
-+
-+/**
-+ * bfq_extract - remove an entity from a tree.
-+ * @root: the tree root.
-+ * @entity: the entity to remove.
-+ */
-+static void bfq_extract(struct rb_root *root, struct bfq_entity *entity)
-+{
-+	BUG_ON(entity->tree != root);
-+
-+	entity->tree = NULL;
-+	rb_erase(&entity->rb_node, root);
-+}
-+
-+/**
-+ * bfq_idle_extract - extract an entity from the idle tree.
-+ * @st: the service tree of the owning @entity.
-+ * @entity: the entity being removed.
-+ */
-+static void bfq_idle_extract(struct bfq_service_tree *st,
-+			     struct bfq_entity *entity)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+	struct rb_node *next;
-+
-+	BUG_ON(entity->tree != &st->idle);
-+
-+	if (entity == st->first_idle) {
-+		next = rb_next(&entity->rb_node);
-+		st->first_idle = bfq_entity_of(next);
-+	}
-+
-+	if (entity == st->last_idle) {
-+		next = rb_prev(&entity->rb_node);
-+		st->last_idle = bfq_entity_of(next);
-+	}
-+
-+	bfq_extract(&st->idle, entity);
-+
-+	if (bfqq)
-+		list_del(&bfqq->bfqq_list);
-+}
-+
-+/**
-+ * bfq_insert - generic tree insertion.
-+ * @root: tree root.
-+ * @entity: entity to insert.
-+ *
-+ * This is used for the idle and the active tree, since they are both
-+ * ordered by finish time.
-+ */
-+static void bfq_insert(struct rb_root *root, struct bfq_entity *entity)
-+{
-+	struct bfq_entity *entry;
-+	struct rb_node **node = &root->rb_node;
-+	struct rb_node *parent = NULL;
-+
-+	BUG_ON(entity->tree);
-+
-+	while (*node) {
-+		parent = *node;
-+		entry = rb_entry(parent, struct bfq_entity, rb_node);
-+
-+		if (bfq_gt(entry->finish, entity->finish))
-+			node = &parent->rb_left;
-+		else
-+			node = &parent->rb_right;
-+	}
-+
-+	rb_link_node(&entity->rb_node, parent, node);
-+	rb_insert_color(&entity->rb_node, root);
-+
-+	entity->tree = root;
-+}
-+
-+/**
-+ * bfq_update_min - update the min_start field of a entity.
-+ * @entity: the entity to update.
-+ * @node: one of its children.
-+ *
-+ * This function is called when @entity may store an invalid value for
-+ * min_start due to updates to the active tree.  The function  assumes
-+ * that the subtree rooted at @node (which may be its left or its right
-+ * child) has a valid min_start value.
-+ */
-+static void bfq_update_min(struct bfq_entity *entity, struct rb_node *node)
-+{
-+	struct bfq_entity *child;
-+
-+	if (node) {
-+		child = rb_entry(node, struct bfq_entity, rb_node);
-+		if (bfq_gt(entity->min_start, child->min_start))
-+			entity->min_start = child->min_start;
-+	}
-+}
-+
-+/**
-+ * bfq_update_active_node - recalculate min_start.
-+ * @node: the node to update.
-+ *
-+ * @node may have changed position or one of its children may have moved,
-+ * this function updates its min_start value.  The left and right subtrees
-+ * are assumed to hold a correct min_start value.
-+ */
-+static void bfq_update_active_node(struct rb_node *node)
-+{
-+	struct bfq_entity *entity = rb_entry(node, struct bfq_entity, rb_node);
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+
-+	entity->min_start = entity->start;
-+	bfq_update_min(entity, node->rb_right);
-+	bfq_update_min(entity, node->rb_left);
-+
-+	if (bfqq) {
-+		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			     "update_active_node: new min_start %llu",
-+			     ((entity->min_start>>10)*1000)>>12);
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	} else {
-+		struct bfq_group *bfqg =
-+			container_of(entity, struct bfq_group, entity);
-+
-+		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+			     "update_active_node: new min_start %llu",
-+			     ((entity->min_start>>10)*1000)>>12);
-+#endif
-+	}
-+}
-+
-+/**
-+ * bfq_update_active_tree - update min_start for the whole active tree.
-+ * @node: the starting node.
-+ *
-+ * @node must be the deepest modified node after an update.  This function
-+ * updates its min_start using the values held by its children, assuming
-+ * that they did not change, and then updates all the nodes that may have
-+ * changed in the path to the root.  The only nodes that may have changed
-+ * are the ones in the path or their siblings.
-+ */
-+static void bfq_update_active_tree(struct rb_node *node)
-+{
-+	struct rb_node *parent;
-+
-+up:
-+	bfq_update_active_node(node);
-+
-+	parent = rb_parent(node);
-+	if (!parent)
-+		return;
-+
-+	if (node == parent->rb_left && parent->rb_right)
-+		bfq_update_active_node(parent->rb_right);
-+	else if (parent->rb_left)
-+		bfq_update_active_node(parent->rb_left);
-+
-+	node = parent;
-+	goto up;
-+}
-+
-+static void bfq_weights_tree_add(struct bfq_data *bfqd,
-+				 struct bfq_entity *entity,
-+				 struct rb_root *root);
-+
-+static void bfq_weights_tree_remove(struct bfq_data *bfqd,
-+				    struct bfq_entity *entity,
-+				    struct rb_root *root);
-+
-+
-+/**
-+ * bfq_active_insert - insert an entity in the active tree of its
-+ *                     group/device.
-+ * @st: the service tree of the entity.
-+ * @entity: the entity being inserted.
-+ *
-+ * The active tree is ordered by finish time, but an extra key is kept
-+ * per each node, containing the minimum value for the start times of
-+ * its children (and the node itself), so it's possible to search for
-+ * the eligible node with the lowest finish time in logarithmic time.
-+ */
-+static void bfq_active_insert(struct bfq_service_tree *st,
-+			      struct bfq_entity *entity)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+	struct rb_node *node = &entity->rb_node;
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	struct bfq_sched_data *sd = NULL;
-+	struct bfq_group *bfqg = NULL;
-+	struct bfq_data *bfqd = NULL;
-+#endif
-+
-+	bfq_insert(&st->active, entity);
-+
-+	if (node->rb_left)
-+		node = node->rb_left;
-+	else if (node->rb_right)
-+		node = node->rb_right;
-+
-+	bfq_update_active_tree(node);
-+
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	sd = entity->sched_data;
-+	bfqg = container_of(sd, struct bfq_group, sched_data);
-+	BUG_ON(!bfqg);
-+	bfqd = (struct bfq_data *)bfqg->bfqd;
-+#endif
-+	if (bfqq)
-+		list_add(&bfqq->bfqq_list, &bfqq->bfqd->active_list);
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	else { /* bfq_group */
-+		BUG_ON(!bfqd);
-+		bfq_weights_tree_add(bfqd, entity, &bfqd->group_weights_tree);
-+	}
-+	if (bfqg != bfqd->root_group) {
-+		BUG_ON(!bfqg);
-+		BUG_ON(!bfqd);
-+		bfqg->active_entities++;
-+	}
-+#endif
-+}
-+
-+/**
-+ * bfq_ioprio_to_weight - calc a weight from an ioprio.
-+ * @ioprio: the ioprio value to convert.
-+ */
-+static unsigned short bfq_ioprio_to_weight(int ioprio)
-+{
-+	BUG_ON(ioprio < 0 || ioprio >= IOPRIO_BE_NR);
-+	return (IOPRIO_BE_NR - ioprio) * BFQ_WEIGHT_CONVERSION_COEFF;
-+}
-+
-+/**
-+ * bfq_weight_to_ioprio - calc an ioprio from a weight.
-+ * @weight: the weight value to convert.
-+ *
-+ * To preserve as much as possible the old only-ioprio user interface,
-+ * 0 is used as an escape ioprio value for weights (numerically) equal or
-+ * larger than IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF.
-+ */
-+static unsigned short bfq_weight_to_ioprio(int weight)
-+{
-+	BUG_ON(weight < BFQ_MIN_WEIGHT || weight > BFQ_MAX_WEIGHT);
-+	return IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF - weight < 0 ?
-+		0 : IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF - weight;
-+}
-+
-+static void bfq_get_entity(struct bfq_entity *entity)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+
-+	if (bfqq) {
-+		bfqq->ref++;
-+		bfq_log_bfqq(bfqq->bfqd, bfqq, "get_entity: %p %d",
-+			     bfqq, bfqq->ref);
-+	}
-+}
-+
-+/**
-+ * bfq_find_deepest - find the deepest node that an extraction can modify.
-+ * @node: the node being removed.
-+ *
-+ * Do the first step of an extraction in an rb tree, looking for the
-+ * node that will replace @node, and returning the deepest node that
-+ * the following modifications to the tree can touch.  If @node is the
-+ * last node in the tree return %NULL.
-+ */
-+static struct rb_node *bfq_find_deepest(struct rb_node *node)
-+{
-+	struct rb_node *deepest;
-+
-+	if (!node->rb_right && !node->rb_left)
-+		deepest = rb_parent(node);
-+	else if (!node->rb_right)
-+		deepest = node->rb_left;
-+	else if (!node->rb_left)
-+		deepest = node->rb_right;
-+	else {
-+		deepest = rb_next(node);
-+		if (deepest->rb_right)
-+			deepest = deepest->rb_right;
-+		else if (rb_parent(deepest) != node)
-+			deepest = rb_parent(deepest);
-+	}
-+
-+	return deepest;
-+}
-+
-+/**
-+ * bfq_active_extract - remove an entity from the active tree.
-+ * @st: the service_tree containing the tree.
-+ * @entity: the entity being removed.
-+ */
-+static void bfq_active_extract(struct bfq_service_tree *st,
-+			       struct bfq_entity *entity)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+	struct rb_node *node;
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	struct bfq_sched_data *sd = NULL;
-+	struct bfq_group *bfqg = NULL;
-+	struct bfq_data *bfqd = NULL;
-+#endif
-+
-+	node = bfq_find_deepest(&entity->rb_node);
-+	bfq_extract(&st->active, entity);
-+
-+	if (node)
-+		bfq_update_active_tree(node);
-+
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	sd = entity->sched_data;
-+	bfqg = container_of(sd, struct bfq_group, sched_data);
-+	BUG_ON(!bfqg);
-+	bfqd = (struct bfq_data *)bfqg->bfqd;
-+#endif
-+	if (bfqq)
-+		list_del(&bfqq->bfqq_list);
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	else { /* bfq_group */
-+		BUG_ON(!bfqd);
-+		bfq_weights_tree_remove(bfqd, entity,
-+					&bfqd->group_weights_tree);
-+	}
-+	if (bfqg != bfqd->root_group) {
-+		BUG_ON(!bfqg);
-+		BUG_ON(!bfqd);
-+		BUG_ON(!bfqg->active_entities);
-+		bfqg->active_entities--;
-+	}
-+#endif
-+}
-+
-+/**
-+ * bfq_idle_insert - insert an entity into the idle tree.
-+ * @st: the service tree containing the tree.
-+ * @entity: the entity to insert.
-+ */
-+static void bfq_idle_insert(struct bfq_service_tree *st,
-+			    struct bfq_entity *entity)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+	struct bfq_entity *first_idle = st->first_idle;
-+	struct bfq_entity *last_idle = st->last_idle;
-+
-+	if (!first_idle || bfq_gt(first_idle->finish, entity->finish))
-+		st->first_idle = entity;
-+	if (!last_idle || bfq_gt(entity->finish, last_idle->finish))
-+		st->last_idle = entity;
-+
-+	bfq_insert(&st->idle, entity);
-+
-+	if (bfqq)
-+		list_add(&bfqq->bfqq_list, &bfqq->bfqd->idle_list);
-+}
-+
-+/**
-+ * bfq_forget_entity - do not consider entity any longer for scheduling
-+ * @st: the service tree.
-+ * @entity: the entity being removed.
-+ * @is_in_service: true if entity is currently the in-service entity.
-+ *
-+ * Forget everything about @entity. In addition, if entity represents
-+ * a queue, and the latter is not in service, then release the service
-+ * reference to the queue (the one taken through bfq_get_entity). In
-+ * fact, in this case, there is really no more service reference to
-+ * the queue, as the latter is also outside any service tree. If,
-+ * instead, the queue is in service, then __bfq_bfqd_reset_in_service
-+ * will take care of putting the reference when the queue finally
-+ * stops being served.
-+ */
-+static void bfq_forget_entity(struct bfq_service_tree *st,
-+			      struct bfq_entity *entity,
-+			      bool is_in_service)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+	BUG_ON(!entity->on_st);
-+
-+	entity->on_st = false;
-+	st->wsum -= entity->weight;
-+	if (bfqq && !is_in_service) {
-+		bfq_log_bfqq(bfqq->bfqd, bfqq, "forget_entity (before): %p %d",
-+			     bfqq, bfqq->ref);
-+		bfq_put_queue(bfqq);
-+	}
-+}
-+
-+/**
-+ * bfq_put_idle_entity - release the idle tree ref of an entity.
-+ * @st: service tree for the entity.
-+ * @entity: the entity being released.
-+ */
-+static void bfq_put_idle_entity(struct bfq_service_tree *st,
-+				struct bfq_entity *entity)
-+{
-+	bfq_idle_extract(st, entity);
-+	bfq_forget_entity(st, entity,
-+			  entity == entity->sched_data->in_service_entity);
-+}
-+
-+/**
-+ * bfq_forget_idle - update the idle tree if necessary.
-+ * @st: the service tree to act upon.
-+ *
-+ * To preserve the global O(log N) complexity we only remove one entry here;
-+ * as the idle tree will not grow indefinitely this can be done safely.
-+ */
-+static void bfq_forget_idle(struct bfq_service_tree *st)
-+{
-+	struct bfq_entity *first_idle = st->first_idle;
-+	struct bfq_entity *last_idle = st->last_idle;
-+
-+	if (RB_EMPTY_ROOT(&st->active) && last_idle &&
-+	    !bfq_gt(last_idle->finish, st->vtime)) {
-+		/*
-+		 * Forget the whole idle tree, increasing the vtime past
-+		 * the last finish time of idle entities.
-+		 */
-+		st->vtime = last_idle->finish;
-+	}
-+
-+	if (first_idle && !bfq_gt(first_idle->finish, st->vtime))
-+		bfq_put_idle_entity(st, first_idle);
-+}
-+
-+/*
-+ * Update weight and priority of entity. If update_class_too is true,
-+ * then update the ioprio_class of entity too.
-+ *
-+ * The reason why the update of ioprio_class is controlled through the
-+ * last parameter is as follows. Changing the ioprio class of an
-+ * entity implies changing the destination service trees for that
-+ * entity. If such a change occurred when the entity is already on one
-+ * of the service trees for its previous class, then the state of the
-+ * entity would become more complex: none of the new possible service
-+ * trees for the entity, according to bfq_entity_service_tree(), would
-+ * match any of the possible service trees on which the entity
-+ * is. Complex operations involving these trees, such as entity
-+ * activations and deactivations, should take into account this
-+ * additional complexity.  To avoid this issue, this function is
-+ * invoked with update_class_too unset in the points in the code where
-+ * entity may happen to be on some tree.
-+ */
-+static struct bfq_service_tree *
-+__bfq_entity_update_weight_prio(struct bfq_service_tree *old_st,
-+				struct bfq_entity *entity,
-+				bool update_class_too)
-+{
-+	struct bfq_service_tree *new_st = old_st;
-+
-+	if (entity->prio_changed) {
-+		struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+		unsigned int prev_weight, new_weight;
-+		struct bfq_data *bfqd = NULL;
-+		struct rb_root *root;
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+		struct bfq_sched_data *sd;
-+		struct bfq_group *bfqg;
-+#endif
-+
-+		if (bfqq)
-+			bfqd = bfqq->bfqd;
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+		else {
-+			sd = entity->my_sched_data;
-+			bfqg = container_of(sd, struct bfq_group, sched_data);
-+			BUG_ON(!bfqg);
-+			bfqd = (struct bfq_data *)bfqg->bfqd;
-+			BUG_ON(!bfqd);
-+		}
-+#endif
-+
-+		BUG_ON(old_st->wsum < entity->weight);
-+		old_st->wsum -= entity->weight;
-+
-+		if (entity->new_weight != entity->orig_weight) {
-+			if (entity->new_weight < BFQ_MIN_WEIGHT ||
-+			    entity->new_weight > BFQ_MAX_WEIGHT) {
-+				pr_crit("update_weight_prio: new_weight %d\n",
-+					entity->new_weight);
-+				if (entity->new_weight < BFQ_MIN_WEIGHT)
-+					entity->new_weight = BFQ_MIN_WEIGHT;
-+				else
-+					entity->new_weight = BFQ_MAX_WEIGHT;
-+			}
-+			entity->orig_weight = entity->new_weight;
-+			if (bfqq)
-+				bfqq->ioprio =
-+				  bfq_weight_to_ioprio(entity->orig_weight);
-+		}
-+
-+		if (bfqq && update_class_too)
-+			bfqq->ioprio_class = bfqq->new_ioprio_class;
-+
-+		/*
-+		 * Reset prio_changed only if the ioprio_class change
-+		 * is not pending any longer.
-+		 */
-+		if (!bfqq || bfqq->ioprio_class == bfqq->new_ioprio_class)
-+			entity->prio_changed = 0;
-+
-+		/*
-+		 * NOTE: here we may be changing the weight too early,
-+		 * this will cause unfairness.  The correct approach
-+		 * would have required additional complexity to defer
-+		 * weight changes to the proper time instants (i.e.,
-+		 * when entity->finish <= old_st->vtime).
-+		 */
-+		new_st = bfq_entity_service_tree(entity);
-+
-+		prev_weight = entity->weight;
-+		new_weight = entity->orig_weight *
-+			     (bfqq ? bfqq->wr_coeff : 1);
-+		/*
-+		 * If the weight of the entity changes, remove the entity
-+		 * from its old weight counter (if there is a counter
-+		 * associated with the entity), and add it to the counter
-+		 * associated with its new weight.
-+		 */
-+		if (prev_weight != new_weight) {
-+			if (bfqq)
-+				bfq_log_bfqq(bfqq->bfqd, bfqq,
-+					     "weight changed %d %d(%d %d)",
-+					     prev_weight, new_weight,
-+					     entity->orig_weight,
-+					     bfqq->wr_coeff);
-+
-+			root = bfqq ? &bfqd->queue_weights_tree :
-+				      &bfqd->group_weights_tree;
-+			bfq_weights_tree_remove(bfqd, entity, root);
-+		}
-+		entity->weight = new_weight;
-+		/*
-+		 * Add the entity to its weights tree only if it is
-+		 * not associated with a weight-raised queue.
-+		 */
-+		if (prev_weight != new_weight &&
-+		    (bfqq ? bfqq->wr_coeff == 1 : 1))
-+			/* If we get here, root has been initialized. */
-+			bfq_weights_tree_add(bfqd, entity, root);
-+
-+		new_st->wsum += entity->weight;
-+
-+		if (new_st != old_st)
-+			entity->start = new_st->vtime;
-+	}
-+
-+	return new_st;
-+}
-+
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+static void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg);
-+#endif
-+
-+/**
-+ * bfq_bfqq_served - update the scheduler status after selection for
-+ *                   service.
-+ * @bfqq: the queue being served.
-+ * @served: bytes to transfer.
-+ *
-+ * NOTE: this can be optimized, as the timestamps of upper level entities
-+ * are synchronized every time a new bfqq is selected for service.  By now,
-+ * we keep it to better check consistency.
-+ */
-+static void bfq_bfqq_served(struct bfq_queue *bfqq, int served)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+	struct bfq_service_tree *st;
-+
-+	for_each_entity(entity) {
-+		st = bfq_entity_service_tree(entity);
-+
-+		entity->service += served;
-+
-+		BUG_ON(st->wsum == 0);
-+
-+		st->vtime += bfq_delta(served, st->wsum);
-+		bfq_forget_idle(st);
-+	}
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	bfqg_stats_set_start_empty_time(bfqq_group(bfqq));
-+#endif
-+	st = bfq_entity_service_tree(&bfqq->entity);
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "bfqq_served %d secs, vtime %llu on %p",
-+		     served,  ((st->vtime>>10)*1000)>>12, st);
-+}
-+
-+/**
-+ * bfq_bfqq_charge_time - charge an amount of service equivalent to the length
-+ *			  of the time interval during which bfqq has been in
-+ *			  service.
-+ * @bfqd: the device
-+ * @bfqq: the queue that needs a service update.
-+ * @time_ms: the amount of time during which the queue has received service
-+ *
-+ * If a queue does not consume its budget fast enough, then providing
-+ * the queue with service fairness may impair throughput, more or less
-+ * severely. For this reason, queues that consume their budget slowly
-+ * are provided with time fairness instead of service fairness. This
-+ * goal is achieved through the BFQ scheduling engine, even if such an
-+ * engine works in the service, and not in the time domain. The trick
-+ * is charging these queues with an inflated amount of service, equal
-+ * to the amount of service that they would have received during their
-+ * service slot if they had been fast, i.e., if their requests had
-+ * been dispatched at a rate equal to the estimated peak rate.
-+ *
-+ * It is worth noting that time fairness can cause important
-+ * distortions in terms of bandwidth distribution, on devices with
-+ * internal queueing. The reason is that I/O requests dispatched
-+ * during the service slot of a queue may be served after that service
-+ * slot is finished, and may have a total processing time loosely
-+ * correlated with the duration of the service slot. This is
-+ * especially true for short service slots.
-+ */
-+static void bfq_bfqq_charge_time(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+				 unsigned long time_ms)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+	int tot_serv_to_charge = entity->service;
-+	unsigned int timeout_ms = jiffies_to_msecs(bfq_timeout);
-+
-+	if (time_ms > 0 && time_ms < timeout_ms)
-+		tot_serv_to_charge =
-+			(bfqd->bfq_max_budget * time_ms) / timeout_ms;
-+
-+	if (tot_serv_to_charge < entity->service)
-+		tot_serv_to_charge = entity->service;
-+
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		     "charge_time: %lu/%u ms, %d/%d/%d sectors",
-+		     time_ms, timeout_ms, entity->service,
-+		     tot_serv_to_charge, entity->budget);
-+
-+	/* Increase budget to avoid inconsistencies */
-+	if (tot_serv_to_charge > entity->budget)
-+		entity->budget = tot_serv_to_charge;
-+
-+	bfq_bfqq_served(bfqq,
-+			max_t(int, 0, tot_serv_to_charge - entity->service));
-+}
-+
-+static void bfq_update_fin_time_enqueue(struct bfq_entity *entity,
-+					struct bfq_service_tree *st,
-+					bool backshifted)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+	struct bfq_sched_data *sd = entity->sched_data;
-+
-+	/*
-+	 * When this function is invoked, entity is not in any service
-+	 * tree, then it is safe to invoke next function with the last
-+	 * parameter set (see the comments on the function).
-+	 */
-+	st = __bfq_entity_update_weight_prio(st, entity, true);
-+	bfq_calc_finish(entity, entity->budget);
-+
-+	/*
-+	 * If some queues enjoy backshifting for a while, then their
-+	 * (virtual) finish timestamps may happen to become lower and
-+	 * lower than the system virtual time.  In particular, if
-+	 * these queues often happen to be idle for short time
-+	 * periods, and during such time periods other queues with
-+	 * higher timestamps happen to be busy, then the backshifted
-+	 * timestamps of the former queues can become much lower than
-+	 * the system virtual time. In fact, to serve the queues with
-+	 * higher timestamps while the ones with lower timestamps are
-+	 * idle, the system virtual time may be pushed-up to much
-+	 * higher values than the finish timestamps of the idle
-+	 * queues. As a consequence, the finish timestamps of all new
-+	 * or newly activated queues may end up being much larger than
-+	 * those of lucky queues with backshifted timestamps. The
-+	 * latter queues may then monopolize the device for a lot of
-+	 * time. This would simply break service guarantees.
-+	 *
-+	 * To reduce this problem, push up a little bit the
-+	 * backshifted timestamps of the queue associated with this
-+	 * entity (only a queue can happen to have the backshifted
-+	 * flag set): just enough to let the finish timestamp of the
-+	 * queue be equal to the current value of the system virtual
-+	 * time. This may introduce a little unfairness among queues
-+	 * with backshifted timestamps, but it does not break
-+	 * worst-case fairness guarantees.
-+	 *
-+	 * As a special case, if bfqq is weight-raised, push up
-+	 * timestamps much less, to keep very low the probability that
-+	 * this push up causes the backshifted finish timestamps of
-+	 * weight-raised queues to become higher than the backshifted
-+	 * finish timestamps of non weight-raised queues.
-+	 */
-+	if (backshifted && bfq_gt(st->vtime, entity->finish)) {
-+		unsigned long delta = st->vtime - entity->finish;
-+
-+		if (bfqq)
-+			delta /= bfqq->wr_coeff;
-+
-+		entity->start += delta;
-+		entity->finish += delta;
-+
-+		if (bfqq) {
-+			bfq_log_bfqq(bfqq->bfqd, bfqq,
-+				     "__activate_entity: new queue finish %llu",
-+				     ((entity->finish>>10)*1000)>>12);
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+		} else {
-+			struct bfq_group *bfqg =
-+				container_of(entity, struct bfq_group, entity);
-+
-+			bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+				     "__activate_entity: new group finish %llu",
-+				     ((entity->finish>>10)*1000)>>12);
-+#endif
-+		}
-+	}
-+
-+	bfq_active_insert(st, entity);
-+
-+	if (bfqq) {
-+		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			"__activate_entity: queue %seligible in st %p",
-+			     entity->start <= st->vtime ? "" : "non ", st);
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	} else {
-+		struct bfq_group *bfqg =
-+			container_of(entity, struct bfq_group, entity);
-+
-+		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+			"__activate_entity: group %seligible in st %p",
-+			     entity->start <= st->vtime ? "" : "non ", st);
-+#endif
-+	}
-+	BUG_ON(RB_EMPTY_ROOT(&st->active));
-+	BUG_ON(&st->active != &sd->service_tree->active &&
-+	       &st->active != &(sd->service_tree+1)->active &&
-+	       &st->active != &(sd->service_tree+2)->active);
-+}
-+
-+/**
-+ * __bfq_activate_entity - handle activation of entity.
-+ * @entity: the entity being activated.
-+ * @non_blocking_wait_rq: true if entity was waiting for a request
-+ *
-+ * Called for a 'true' activation, i.e., if entity is not active and
-+ * one of its children receives a new request.
-+ *
-+ * Basically, this function updates the timestamps of entity and
-+ * inserts entity into its active tree, ater possible extracting it
-+ * from its idle tree.
-+ */
-+static void __bfq_activate_entity(struct bfq_entity *entity,
-+				  bool non_blocking_wait_rq)
-+{
-+	struct bfq_sched_data *sd = entity->sched_data;
-+	struct bfq_service_tree *st = bfq_entity_service_tree(entity);
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+	bool backshifted = false;
-+	unsigned long long min_vstart;
-+
-+	BUG_ON(!sd);
-+	BUG_ON(!st);
-+
-+	/* See comments on bfq_fqq_update_budg_for_activation */
-+	if (non_blocking_wait_rq && bfq_gt(st->vtime, entity->finish)) {
-+		backshifted = true;
-+		min_vstart = entity->finish;
-+	} else
-+		min_vstart = st->vtime;
-+
-+	if (entity->tree == &st->idle) {
-+		/*
-+		 * Must be on the idle tree, bfq_idle_extract() will
-+		 * check for that.
-+		 */
-+		bfq_idle_extract(st, entity);
-+		entity->start = bfq_gt(min_vstart, entity->finish) ?
-+			min_vstart : entity->finish;
-+	} else {
-+		/*
-+		 * The finish time of the entity may be invalid, and
-+		 * it is in the past for sure, otherwise the queue
-+		 * would have been on the idle tree.
-+		 */
-+		entity->start = min_vstart;
-+		st->wsum += entity->weight;
-+		/*
-+		 * entity is about to be inserted into a service tree,
-+		 * and then set in service: get a reference to make
-+		 * sure entity does not disappear until it is no
-+		 * longer in service or scheduled for service.
-+		 */
-+		bfq_get_entity(entity);
-+
-+		BUG_ON(entity->on_st && bfqq);
-+
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+		if (entity->on_st && !bfqq) {
-+			struct bfq_group *bfqg =
-+				container_of(entity, struct bfq_group,
-+					     entity);
-+
-+			bfq_log_bfqg((struct bfq_data *)bfqg->bfqd,
-+				     bfqg,
-+				     "activate bug, class %d in_service %p",
-+				     bfq_class_idx(entity), sd->in_service_entity);
-+		}
-+#endif
-+		BUG_ON(entity->on_st && !bfqq);
-+		entity->on_st = true;
-+	}
-+
-+	bfq_update_fin_time_enqueue(entity, st, backshifted);
-+}
-+
-+/**
-+ * __bfq_requeue_entity - handle requeueing or repositioning of an entity.
-+ * @entity: the entity being requeued or repositioned.
-+ *
-+ * Requeueing is needed if this entity stops being served, which
-+ * happens if a leaf descendant entity has expired. On the other hand,
-+ * repositioning is needed if the next_inservice_entity for the child
-+ * entity has changed. See the comments inside the function for
-+ * details.
-+ *
-+ * Basically, this function: 1) removes entity from its active tree if
-+ * present there, 2) updates the timestamps of entity and 3) inserts
-+ * entity back into its active tree (in the new, right position for
-+ * the new values of the timestamps).
-+ */
-+static void __bfq_requeue_entity(struct bfq_entity *entity)
-+{
-+	struct bfq_sched_data *sd = entity->sched_data;
-+	struct bfq_service_tree *st = bfq_entity_service_tree(entity);
-+
-+	BUG_ON(!sd);
-+	BUG_ON(!st);
-+
-+	BUG_ON(entity != sd->in_service_entity &&
-+	       entity->tree != &st->active);
-+
-+	if (entity == sd->in_service_entity) {
-+		/*
-+		 * We are requeueing the current in-service entity,
-+		 * which may have to be done for one of the following
-+		 * reasons:
-+		 * - entity represents the in-service queue, and the
-+		 *   in-service queue is being requeued after an
-+		 *   expiration;
-+		 * - entity represents a group, and its budget has
-+		 *   changed because one of its child entities has
-+		 *   just been either activated or requeued for some
-+		 *   reason; the timestamps of the entity need then to
-+		 *   be updated, and the entity needs to be enqueued
-+		 *   or repositioned accordingly.
-+		 *
-+		 * In particular, before requeueing, the start time of
-+		 * the entity must be moved forward to account for the
-+		 * service that the entity has received while in
-+		 * service. This is done by the next instructions. The
-+		 * finish time will then be updated according to this
-+		 * new value of the start time, and to the budget of
-+		 * the entity.
-+		 */
-+		bfq_calc_finish(entity, entity->service);
-+		entity->start = entity->finish;
-+		BUG_ON(entity->tree && entity->tree != &st->active);
-+		/*
-+		 * In addition, if the entity had more than one child
-+		 * when set in service, then was not extracted from
-+		 * the active tree. This implies that the position of
-+		 * the entity in the active tree may need to be
-+		 * changed now, because we have just updated the start
-+		 * time of the entity, and we will update its finish
-+		 * time in a moment (the requeueing is then, more
-+		 * precisely, a repositioning in this case). To
-+		 * implement this repositioning, we: 1) dequeue the
-+		 * entity here, 2) update the finish time and
-+		 * requeue the entity according to the new
-+		 * timestamps below.
-+		 */
-+		if (entity->tree)
-+			bfq_active_extract(st, entity);
-+	} else { /* The entity is already active, and not in service */
-+		/*
-+		 * In this case, this function gets called only if the
-+		 * next_in_service entity below this entity has
-+		 * changed, and this change has caused the budget of
-+		 * this entity to change, which, finally implies that
-+		 * the finish time of this entity must be
-+		 * updated. Such an update may cause the scheduling,
-+		 * i.e., the position in the active tree, of this
-+		 * entity to change. We handle this change by: 1)
-+		 * dequeueing the entity here, 2) updating the finish
-+		 * time and requeueing the entity according to the new
-+		 * timestamps below. This is the same approach as the
-+		 * non-extracted-entity sub-case above.
-+		 */
-+		bfq_active_extract(st, entity);
-+	}
-+
-+	bfq_update_fin_time_enqueue(entity, st, false);
-+}
-+
-+static void __bfq_activate_requeue_entity(struct bfq_entity *entity,
-+					  struct bfq_sched_data *sd,
-+					  bool non_blocking_wait_rq)
-+{
-+	struct bfq_service_tree *st = bfq_entity_service_tree(entity);
-+
-+	if (sd->in_service_entity == entity || entity->tree == &st->active)
-+		 /*
-+		  * in service or already queued on the active tree,
-+		  * requeue or reposition
-+		  */
-+		__bfq_requeue_entity(entity);
-+	else
-+		/*
-+		 * Not in service and not queued on its active tree:
-+		 * the activity is idle and this is a true activation.
-+		 */
-+		__bfq_activate_entity(entity, non_blocking_wait_rq);
-+}
-+
-+
-+/**
-+ * bfq_activate_entity - activate or requeue an entity representing a bfq_queue,
-+ *			 and activate, requeue or reposition all ancestors
-+ *			 for which such an update becomes necessary.
-+ * @entity: the entity to activate.
-+ * @non_blocking_wait_rq: true if this entity was waiting for a request
-+ * @requeue: true if this is a requeue, which implies that bfqq is
-+ *	     being expired; thus ALL its ancestors stop being served and must
-+ *	     therefore be requeued
-+ */
-+static void bfq_activate_requeue_entity(struct bfq_entity *entity,
-+					bool non_blocking_wait_rq,
-+					bool requeue)
-+{
-+	struct bfq_sched_data *sd;
-+
-+	for_each_entity(entity) {
-+		BUG_ON(!entity);
-+		sd = entity->sched_data;
-+		__bfq_activate_requeue_entity(entity, sd, non_blocking_wait_rq);
-+
-+		BUG_ON(RB_EMPTY_ROOT(&sd->service_tree->active) &&
-+		       RB_EMPTY_ROOT(&(sd->service_tree+1)->active) &&
-+		       RB_EMPTY_ROOT(&(sd->service_tree+2)->active));
-+
-+		if (!bfq_update_next_in_service(sd, entity) && !requeue) {
-+			BUG_ON(!sd->next_in_service);
-+			break;
-+		}
-+		BUG_ON(!sd->next_in_service);
-+	}
-+}
-+
-+/**
-+ * __bfq_deactivate_entity - deactivate an entity from its service tree.
-+ * @entity: the entity to deactivate.
-+ * @ins_into_idle_tree: if false, the entity will not be put into the
-+ *			idle tree.
-+ *
-+ * Deactivates an entity, independently from its previous state.  Must
-+ * be invoked only if entity is on a service tree. Extracts the entity
-+ * from that tree, and if necessary and allowed, puts it on the idle
-+ * tree.
-+ */
-+static bool __bfq_deactivate_entity(struct bfq_entity *entity,
-+				    bool ins_into_idle_tree)
-+{
-+	struct bfq_sched_data *sd = entity->sched_data;
-+	struct bfq_service_tree *st;
-+	bool is_in_service;
-+
-+	if (!entity->on_st) { /* entity never activated, or already inactive */
-+		BUG_ON(sd && entity == sd->in_service_entity);
-+		return false;
-+	}
-+
-+	/*
-+	 * If we get here, then entity is active, which implies that
-+	 * bfq_group_set_parent has already been invoked for the group
-+	 * represented by entity. Therefore, the field
-+	 * entity->sched_data has been set, and we can safely use it.
-+	 */
-+	st = bfq_entity_service_tree(entity);
-+	is_in_service = entity == sd->in_service_entity;
-+
-+	BUG_ON(is_in_service && entity->tree && entity->tree != &st->active);
-+
-+	if (is_in_service)
-+		bfq_calc_finish(entity, entity->service);
-+
-+	if (entity->tree == &st->active)
-+		bfq_active_extract(st, entity);
-+	else if (!is_in_service && entity->tree == &st->idle)
-+		bfq_idle_extract(st, entity);
-+	else if (entity->tree)
-+		BUG();
-+
-+	if (!ins_into_idle_tree || !bfq_gt(entity->finish, st->vtime))
-+		bfq_forget_entity(st, entity, is_in_service);
-+	else
-+		bfq_idle_insert(st, entity);
-+
-+	return true;
-+}
-+
-+/**
-+ * bfq_deactivate_entity - deactivate an entity representing a bfq_queue.
-+ * @entity: the entity to deactivate.
-+ * @ins_into_idle_tree: true if the entity can be put on the idle tree
-+ */
-+static void bfq_deactivate_entity(struct bfq_entity *entity,
-+				  bool ins_into_idle_tree,
-+				  bool expiration)
-+{
-+	struct bfq_sched_data *sd;
-+	struct bfq_entity *parent = NULL;
-+
-+	for_each_entity_safe(entity, parent) {
-+		sd = entity->sched_data;
-+
-+		BUG_ON(sd == NULL); /*
-+				     * It would mean that this is the
-+				     * root group.
-+				     */
-+
-+		BUG_ON(expiration && entity != sd->in_service_entity);
-+
-+		BUG_ON(entity != sd->in_service_entity &&
-+		       entity->tree ==
-+		       &bfq_entity_service_tree(entity)->active &&
-+		       !sd->next_in_service);
-+
-+		if (!__bfq_deactivate_entity(entity, ins_into_idle_tree)) {
-+			/*
-+			 * entity is not in any tree any more, so
-+			 * this deactivation is a no-op, and there is
-+			 * nothing to change for upper-level entities
-+			 * (in case of expiration, this can never
-+			 * happen).
-+			 */
-+			BUG_ON(expiration); /*
-+					     * entity cannot be already out of
-+					     * any tree
-+					     */
-+			return;
-+		}
-+
-+		if (sd->next_in_service == entity)
-+			/*
-+			 * entity was the next_in_service entity,
-+			 * then, since entity has just been
-+			 * deactivated, a new one must be found.
-+			 */
-+			bfq_update_next_in_service(sd, NULL);
-+
-+		if (sd->next_in_service) {
-+			/*
-+			 * The parent entity is still backlogged,
-+			 * because next_in_service is not NULL. So, no
-+			 * further upwards deactivation must be
-+			 * performed.  Yet, next_in_service has
-+			 * changed.  Then the schedule does need to be
-+			 * updated upwards.
-+			 */
-+			BUG_ON(sd->next_in_service == entity);
-+			break;
-+		}
-+
-+		/*
-+		 * If we get here, then the parent is no more
-+		 * backlogged and we need to propagate the
-+		 * deactivation upwards. Thus let the loop go on.
-+		 */
-+
-+		/*
-+		 * Also let parent be queued into the idle tree on
-+		 * deactivation, to preserve service guarantees, and
-+		 * assuming that who invoked this function does not
-+		 * need parent entities too to be removed completely.
-+		 */
-+		ins_into_idle_tree = true;
-+	}
-+
-+	/*
-+	 * If the deactivation loop is fully executed, then there are
-+	 * no more entities to touch and next loop is not executed at
-+	 * all. Otherwise, requeue remaining entities if they are
-+	 * about to stop receiving service, or reposition them if this
-+	 * is not the case.
-+	 */
-+	entity = parent;
-+	for_each_entity(entity) {
-+		struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+
-+		/*
-+		 * Invoke __bfq_requeue_entity on entity, even if
-+		 * already active, to requeue/reposition it in the
-+		 * active tree (because sd->next_in_service has
-+		 * changed)
-+		 */
-+		__bfq_requeue_entity(entity);
-+
-+		sd = entity->sched_data;
-+		BUG_ON(expiration && sd->in_service_entity != entity);
-+
-+		if (bfqq)
-+			bfq_log_bfqq(bfqq->bfqd, bfqq,
-+				     "invoking udpdate_next for this queue");
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+		else {
-+			struct bfq_group *bfqg =
-+				container_of(entity,
-+					     struct bfq_group, entity);
-+
-+			bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+				     "invoking udpdate_next for this entity");
-+		}
-+#endif
-+		if (!bfq_update_next_in_service(sd, entity) &&
-+		    !expiration)
-+			/*
-+			 * next_in_service unchanged or not causing
-+			 * any change in entity->parent->sd, and no
-+			 * requeueing needed for expiration: stop
-+			 * here.
-+			 */
-+			break;
-+	}
-+}
-+
-+/**
-+ * bfq_calc_vtime_jump - compute the value to which the vtime should jump,
-+ *                       if needed, to have at least one entity eligible.
-+ * @st: the service tree to act upon.
-+ *
-+ * Assumes that st is not empty.
-+ */
-+static u64 bfq_calc_vtime_jump(struct bfq_service_tree *st)
-+{
-+	struct bfq_entity *root_entity = bfq_root_active_entity(&st->active);
-+
-+	if (bfq_gt(root_entity->min_start, st->vtime)) {
-+		struct bfq_queue *bfqq = bfq_entity_to_bfqq(root_entity);
-+
-+		if (bfqq)
-+			bfq_log_bfqq(bfqq->bfqd, bfqq,
-+				     "calc_vtime_jump: new value %llu",
-+				     root_entity->min_start);
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+		else {
-+			struct bfq_group *bfqg =
-+				container_of(root_entity, struct bfq_group,
-+					     entity);
-+
-+			bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+				     "calc_vtime_jump: new value %llu",
-+				     root_entity->min_start);
-+		}
-+#endif
-+		return root_entity->min_start;
-+	}
-+	return st->vtime;
-+}
-+
-+static void bfq_update_vtime(struct bfq_service_tree *st, u64 new_value)
-+{
-+	if (new_value > st->vtime) {
-+		st->vtime = new_value;
-+		bfq_forget_idle(st);
-+	}
-+}
-+
-+/**
-+ * bfq_first_active_entity - find the eligible entity with
-+ *                           the smallest finish time
-+ * @st: the service tree to select from.
-+ * @vtime: the system virtual to use as a reference for eligibility
-+ *
-+ * This function searches the first schedulable entity, starting from the
-+ * root of the tree and going on the left every time on this side there is
-+ * a subtree with at least one eligible (start >= vtime) entity. The path on
-+ * the right is followed only if a) the left subtree contains no eligible
-+ * entities and b) no eligible entity has been found yet.
-+ */
-+static struct bfq_entity *bfq_first_active_entity(struct bfq_service_tree *st,
-+						  u64 vtime)
-+{
-+	struct bfq_entity *entry, *first = NULL;
-+	struct rb_node *node = st->active.rb_node;
-+
-+	while (node) {
-+		entry = rb_entry(node, struct bfq_entity, rb_node);
-+left:
-+		if (!bfq_gt(entry->start, vtime))
-+			first = entry;
-+
-+		BUG_ON(bfq_gt(entry->min_start, vtime));
-+
-+		if (node->rb_left) {
-+			entry = rb_entry(node->rb_left,
-+					 struct bfq_entity, rb_node);
-+			if (!bfq_gt(entry->min_start, vtime)) {
-+				node = node->rb_left;
-+				goto left;
-+			}
-+		}
-+		if (first)
-+			break;
-+		node = node->rb_right;
-+	}
-+
-+	BUG_ON(!first && !RB_EMPTY_ROOT(&st->active));
-+	return first;
-+}
-+
-+/**
-+ * __bfq_lookup_next_entity - return the first eligible entity in @st.
-+ * @st: the service tree.
-+ *
-+ * If there is no in-service entity for the sched_data st belongs to,
-+ * then return the entity that will be set in service if:
-+ * 1) the parent entity this st belongs to is set in service;
-+ * 2) no entity belonging to such parent entity undergoes a state change
-+ * that would influence the timestamps of the entity (e.g., becomes idle,
-+ * becomes backlogged, changes its budget, ...).
-+ *
-+ * In this first case, update the virtual time in @st too (see the
-+ * comments on this update inside the function).
-+ *
-+ * In constrast, if there is an in-service entity, then return the
-+ * entity that would be set in service if not only the above
-+ * conditions, but also the next one held true: the currently
-+ * in-service entity, on expiration,
-+ * 1) gets a finish time equal to the current one, or
-+ * 2) is not eligible any more, or
-+ * 3) is idle.
-+ */
-+static struct bfq_entity *
-+__bfq_lookup_next_entity(struct bfq_service_tree *st, bool in_service
-+#if 0
-+			 , bool force
-+#endif
-+	)
-+{
-+	struct bfq_entity *entity
-+#if 0
-+		, *new_next_in_service = NULL
-+#endif
-+		;
-+	u64 new_vtime;
-+	struct bfq_queue *bfqq;
-+
-+	if (RB_EMPTY_ROOT(&st->active))
-+		return NULL;
-+
-+	/*
-+	 * Get the value of the system virtual time for which at
-+	 * least one entity is eligible.
-+	 */
-+	new_vtime = bfq_calc_vtime_jump(st);
-+
-+	/*
-+	 * If there is no in-service entity for the sched_data this
-+	 * active tree belongs to, then push the system virtual time
-+	 * up to the value that guarantees that at least one entity is
-+	 * eligible. If, instead, there is an in-service entity, then
-+	 * do not make any such update, because there is already an
-+	 * eligible entity, namely the in-service one (even if the
-+	 * entity is not on st, because it was extracted when set in
-+	 * service).
-+	 */
-+	if (!in_service)
-+		bfq_update_vtime(st, new_vtime);
-+
-+	entity = bfq_first_active_entity(st, new_vtime);
-+	BUG_ON(bfq_gt(entity->start, new_vtime));
-+
-+	/* Log some information */
-+	bfqq = bfq_entity_to_bfqq(entity);
-+	if (bfqq)
-+		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			     "__lookup_next: start %llu vtime %llu st %p",
-+			     ((entity->start>>10)*1000)>>12,
-+			     ((new_vtime>>10)*1000)>>12, st);
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	else {
-+		struct bfq_group *bfqg =
-+			container_of(entity, struct bfq_group, entity);
-+
-+		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+			     "__lookup_next: start %llu vtime %llu st %p",
-+			     ((entity->start>>10)*1000)>>12,
-+			     ((new_vtime>>10)*1000)>>12, st);
-+	}
-+#endif
-+
-+	BUG_ON(!entity);
-+
-+	return entity;
-+}
-+
-+/**
-+ * bfq_lookup_next_entity - return the first eligible entity in @sd.
-+ * @sd: the sched_data.
-+ *
-+ * This function is invoked when there has been a change in the trees
-+ * for sd, and we need know what is the new next entity after this
-+ * change.
-+ */
-+static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd)
-+{
-+	struct bfq_service_tree *st = sd->service_tree;
-+	struct bfq_service_tree *idle_class_st = st + (BFQ_IOPRIO_CLASSES - 1);
-+	struct bfq_entity *entity = NULL;
-+	struct bfq_queue *bfqq;
-+	int class_idx = 0;
-+
-+	BUG_ON(!sd);
-+	BUG_ON(!st);
-+	/*
-+	 * Choose from idle class, if needed to guarantee a minimum
-+	 * bandwidth to this class (and if there is some active entity
-+	 * in idle class). This should also mitigate
-+	 * priority-inversion problems in case a low priority task is
-+	 * holding file system resources.
-+	 */
-+	if (time_is_before_jiffies(sd->bfq_class_idle_last_service +
-+				   BFQ_CL_IDLE_TIMEOUT)) {
-+		if (!RB_EMPTY_ROOT(&idle_class_st->active))
-+			class_idx = BFQ_IOPRIO_CLASSES - 1;
-+		/* About to be served if backlogged, or not yet backlogged */
-+		sd->bfq_class_idle_last_service = jiffies;
-+	}
-+
-+	/*
-+	 * Find the next entity to serve for the highest-priority
-+	 * class, unless the idle class needs to be served.
-+	 */
-+	for (; class_idx < BFQ_IOPRIO_CLASSES; class_idx++) {
-+		entity = __bfq_lookup_next_entity(st + class_idx,
-+						  sd->in_service_entity);
-+
-+		if (entity)
-+			break;
-+	}
-+
-+	BUG_ON(!entity &&
-+	       (!RB_EMPTY_ROOT(&st->active) || !RB_EMPTY_ROOT(&(st+1)->active) ||
-+		!RB_EMPTY_ROOT(&(st+2)->active)));
-+
-+	if (!entity)
-+		return NULL;
-+
-+	/* Log some information */
-+	bfqq = bfq_entity_to_bfqq(entity);
-+	if (bfqq)
-+		bfq_log_bfqq(bfqq->bfqd, bfqq, "chosen from st %p %d",
-+			     st + class_idx, class_idx);
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	else {
-+		struct bfq_group *bfqg =
-+			container_of(entity, struct bfq_group, entity);
-+
-+		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+			     "chosen from st %p %d",
-+			     st + class_idx, class_idx);
-+	}
-+#endif
-+
-+	return entity;
-+}
-+
-+static bool next_queue_may_preempt(struct bfq_data *bfqd)
-+{
-+	struct bfq_sched_data *sd = &bfqd->root_group->sched_data;
-+
-+	return sd->next_in_service != sd->in_service_entity;
-+}
-+
-+/*
-+ * Get next queue for service.
-+ */
-+static struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd)
-+{
-+	struct bfq_entity *entity = NULL;
-+	struct bfq_sched_data *sd;
-+	struct bfq_queue *bfqq;
-+
-+	BUG_ON(bfqd->in_service_queue);
-+
-+	if (bfqd->busy_queues == 0)
-+		return NULL;
-+
-+	/*
-+	 * Traverse the path from the root to the leaf entity to
-+	 * serve. Set in service all the entities visited along the
-+	 * way.
-+	 */
-+	sd = &bfqd->root_group->sched_data;
-+	for (; sd ; sd = entity->my_sched_data) {
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+		if (entity) {
-+			struct bfq_group *bfqg =
-+				container_of(entity, struct bfq_group, entity);
-+
-+			bfq_log_bfqg(bfqd, bfqg,
-+				     "get_next_queue: lookup in this group");
-+			if (!sd->next_in_service)
-+				pr_crit("get_next_queue: lookup in this group");
-+		} else {
-+			bfq_log_bfqg(bfqd, bfqd->root_group,
-+				     "get_next_queue: lookup in root group");
-+			if (!sd->next_in_service)
-+				pr_crit("get_next_queue: lookup in root group");
-+		}
-+#endif
-+
-+		BUG_ON(!sd->next_in_service);
-+
-+		/*
-+		 * WARNING. We are about to set the in-service entity
-+		 * to sd->next_in_service, i.e., to the (cached) value
-+		 * returned by bfq_lookup_next_entity(sd) the last
-+		 * time it was invoked, i.e., the last time when the
-+		 * service order in sd changed as a consequence of the
-+		 * activation or deactivation of an entity. In this
-+		 * respect, if we execute bfq_lookup_next_entity(sd)
-+		 * in this very moment, it may, although with low
-+		 * probability, yield a different entity than that
-+		 * pointed to by sd->next_in_service. This rare event
-+		 * happens in case there was no CLASS_IDLE entity to
-+		 * serve for sd when bfq_lookup_next_entity(sd) was
-+		 * invoked for the last time, while there is now one
-+		 * such entity.
-+		 *
-+		 * If the above event happens, then the scheduling of
-+		 * such entity in CLASS_IDLE is postponed until the
-+		 * service of the sd->next_in_service entity
-+		 * finishes. In fact, when the latter is expired,
-+		 * bfq_lookup_next_entity(sd) gets called again,
-+		 * exactly to update sd->next_in_service.
-+		 */
-+
-+		/* Make next_in_service entity become in_service_entity */
-+		entity = sd->next_in_service;
-+		sd->in_service_entity = entity;
-+
-+		/*
-+		 * Reset the accumulator of the amount of service that
-+		 * the entity is about to receive.
-+		 */
-+		entity->service = 0;
-+
-+		/*
-+		 * If entity is no longer a candidate for next
-+		 * service, then we extract it from its active tree,
-+		 * for the following reason. To further boost the
-+		 * throughput in some special case, BFQ needs to know
-+		 * which is the next candidate entity to serve, while
-+		 * there is already an entity in service. In this
-+		 * respect, to make it easy to compute/update the next
-+		 * candidate entity to serve after the current
-+		 * candidate has been set in service, there is a case
-+		 * where it is necessary to extract the current
-+		 * candidate from its service tree. Such a case is
-+		 * when the entity just set in service cannot be also
-+		 * a candidate for next service. Details about when
-+		 * this conditions holds are reported in the comments
-+		 * on the function bfq_no_longer_next_in_service()
-+		 * invoked below.
-+		 */
-+		if (bfq_no_longer_next_in_service(entity))
-+			bfq_active_extract(bfq_entity_service_tree(entity),
-+					   entity);
-+
-+		/*
-+		 * For the same reason why we may have just extracted
-+		 * entity from its active tree, we may need to update
-+		 * next_in_service for the sched_data of entity too,
-+		 * regardless of whether entity has been extracted.
-+		 * In fact, even if entity has not been extracted, a
-+		 * descendant entity may get extracted. Such an event
-+		 * would cause a change in next_in_service for the
-+		 * level of the descendant entity, and thus possibly
-+		 * back to upper levels.
-+		 *
-+		 * We cannot perform the resulting needed update
-+		 * before the end of this loop, because, to know which
-+		 * is the correct next-to-serve candidate entity for
-+		 * each level, we need first to find the leaf entity
-+		 * to set in service. In fact, only after we know
-+		 * which is the next-to-serve leaf entity, we can
-+		 * discover whether the parent entity of the leaf
-+		 * entity becomes the next-to-serve, and so on.
-+		 */
-+
-+		/* Log some information */
-+		bfqq = bfq_entity_to_bfqq(entity);
-+		if (bfqq)
-+			bfq_log_bfqq(bfqd, bfqq,
-+			     "get_next_queue: this queue, finish %llu",
-+				(((entity->finish>>10)*1000)>>10)>>2);
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+		else {
-+			struct bfq_group *bfqg =
-+				container_of(entity, struct bfq_group, entity);
-+
-+			bfq_log_bfqg(bfqd, bfqg,
-+			     "get_next_queue: this entity, finish %llu",
-+				(((entity->finish>>10)*1000)>>10)>>2);
-+		}
-+#endif
-+
-+	}
-+
-+	BUG_ON(!entity);
-+	bfqq = bfq_entity_to_bfqq(entity);
-+	BUG_ON(!bfqq);
-+
-+	/*
-+	 * We can finally update all next-to-serve entities along the
-+	 * path from the leaf entity just set in service to the root.
-+	 */
-+	for_each_entity(entity) {
-+		struct bfq_sched_data *sd = entity->sched_data;
-+
-+		if(!bfq_update_next_in_service(sd, NULL))
-+			break;
-+	}
-+
-+	return bfqq;
-+}
-+
-+static void __bfq_bfqd_reset_in_service(struct bfq_data *bfqd)
-+{
-+	struct bfq_queue *in_serv_bfqq = bfqd->in_service_queue;
-+	struct bfq_entity *in_serv_entity = &in_serv_bfqq->entity;
-+	struct bfq_entity *entity = in_serv_entity;
-+
-+	if (bfqd->in_service_bic) {
-+		put_io_context(bfqd->in_service_bic->icq.ioc);
-+		bfqd->in_service_bic = NULL;
-+	}
-+
-+	bfq_clear_bfqq_wait_request(in_serv_bfqq);
-+	hrtimer_try_to_cancel(&bfqd->idle_slice_timer);
-+	bfqd->in_service_queue = NULL;
-+
-+	/*
-+	 * When this function is called, all in-service entities have
-+	 * been properly deactivated or requeued, so we can safely
-+	 * execute the final step: reset in_service_entity along the
-+	 * path from entity to the root.
-+	 */
-+	for_each_entity(entity)
-+		entity->sched_data->in_service_entity = NULL;
-+
-+	/*
-+	 * in_serv_entity is no longer in service, so, if it is in no
-+	 * service tree either, then release the service reference to
-+	 * the queue it represents (taken with bfq_get_entity).
-+	 */
-+	if (!in_serv_entity->on_st)
-+		bfq_put_queue(in_serv_bfqq);
-+}
-+
-+static void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+				bool ins_into_idle_tree, bool expiration)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+
-+	bfq_deactivate_entity(entity, ins_into_idle_tree, expiration);
-+}
-+
-+static void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+	struct bfq_service_tree *st = bfq_entity_service_tree(entity);
-+
-+	BUG_ON(bfqq == bfqd->in_service_queue);
-+	BUG_ON(entity->tree != &st->active && entity->tree != &st->idle &&
-+	       entity->on_st);
-+
-+	bfq_activate_requeue_entity(entity, bfq_bfqq_non_blocking_wait_rq(bfqq),
-+				    false);
-+	bfq_clear_bfqq_non_blocking_wait_rq(bfqq);
-+}
-+
-+static void bfq_requeue_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+
-+	bfq_activate_requeue_entity(entity, false,
-+				    bfqq == bfqd->in_service_queue);
-+}
-+
-+static void bfqg_stats_update_dequeue(struct bfq_group *bfqg);
-+
-+/*
-+ * Called when the bfqq no longer has requests pending, remove it from
-+ * the service tree. As a special case, it can be invoked during an
-+ * expiration.
-+ */
-+static void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+			      bool expiration)
-+{
-+	BUG_ON(!bfq_bfqq_busy(bfqq));
-+	BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list));
-+
-+	bfq_log_bfqq(bfqd, bfqq, "del from busy");
-+
-+	bfq_clear_bfqq_busy(bfqq);
-+
-+	BUG_ON(bfqd->busy_queues == 0);
-+	bfqd->busy_queues--;
-+
-+	if (!bfqq->dispatched)
-+		bfq_weights_tree_remove(bfqd, &bfqq->entity,
-+					&bfqd->queue_weights_tree);
-+
-+	if (bfqq->wr_coeff > 1) {
-+		bfqd->wr_busy_queues--;
-+		BUG_ON(bfqd->wr_busy_queues < 0);
-+	}
-+
-+	bfqg_stats_update_dequeue(bfqq_group(bfqq));
-+
-+	BUG_ON(bfqq->entity.budget < 0);
-+
-+	bfq_deactivate_bfqq(bfqd, bfqq, true, expiration);
-+}
-+
-+/*
-+ * Called when an inactive queue receives a new request.
-+ */
-+static void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	BUG_ON(bfq_bfqq_busy(bfqq));
-+	BUG_ON(bfqq == bfqd->in_service_queue);
-+
-+	bfq_log_bfqq(bfqd, bfqq, "add to busy");
-+
-+	bfq_activate_bfqq(bfqd, bfqq);
-+
-+	bfq_mark_bfqq_busy(bfqq);
-+	bfqd->busy_queues++;
-+
-+	if (!bfqq->dispatched)
-+		if (bfqq->wr_coeff == 1)
-+			bfq_weights_tree_add(bfqd, &bfqq->entity,
-+					     &bfqd->queue_weights_tree);
-+
-+	if (bfqq->wr_coeff > 1) {
-+		bfqd->wr_busy_queues++;
-+		BUG_ON(bfqd->wr_busy_queues > bfqd->busy_queues);
-+	}
-+
-+}
-diff --git a/block/bfq-sq-iosched.c b/block/bfq-sq-iosched.c
-new file mode 100644
-index 000000000000..65e7c7e77f3c
---- /dev/null
-+++ b/block/bfq-sq-iosched.c
-@@ -0,0 +1,5379 @@
-+/*
-+ * Budget Fair Queueing (BFQ) I/O scheduler.
-+ *
-+ * Based on ideas and code from CFQ:
-+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
-+ *
-+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
-+ *		      Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2017 Paolo Valente <paolo.valente@linaro.org>
-+ *
-+ * Licensed under the GPL-2 as detailed in the accompanying COPYING.BFQ
-+ * file.
-+ *
-+ * BFQ is a proportional-share I/O scheduler, with some extra
-+ * low-latency capabilities. BFQ also supports full hierarchical
-+ * scheduling through cgroups. Next paragraphs provide an introduction
-+ * on BFQ inner workings. Details on BFQ benefits and usage can be
-+ * found in Documentation/block/bfq-iosched.txt.
-+ *
-+ * BFQ is a proportional-share storage-I/O scheduling algorithm based
-+ * on the slice-by-slice service scheme of CFQ. But BFQ assigns
-+ * budgets, measured in number of sectors, to processes instead of
-+ * time slices. The device is not granted to the in-service process
-+ * for a given time slice, but until it has exhausted its assigned
-+ * budget. This change from the time to the service domain enables BFQ
-+ * to distribute the device throughput among processes as desired,
-+ * without any distortion due to throughput fluctuations, or to device
-+ * internal queueing. BFQ uses an ad hoc internal scheduler, called
-+ * B-WF2Q+, to schedule processes according to their budgets. More
-+ * precisely, BFQ schedules queues associated with processes. Thanks to
-+ * the accurate policy of B-WF2Q+, BFQ can afford to assign high
-+ * budgets to I/O-bound processes issuing sequential requests (to
-+ * boost the throughput), and yet guarantee a low latency to
-+ * interactive and soft real-time applications.
-+ *
-+ * NOTE: if the main or only goal, with a given device, is to achieve
-+ * the maximum-possible throughput at all times, then do switch off
-+ * all low-latency heuristics for that device, by setting low_latency
-+ * to 0.
-+ *
-+ * BFQ is described in [1], where also a reference to the initial, more
-+ * theoretical paper on BFQ can be found. The interested reader can find
-+ * in the latter paper full details on the main algorithm, as well as
-+ * formulas of the guarantees and formal proofs of all the properties.
-+ * With respect to the version of BFQ presented in these papers, this
-+ * implementation adds a few more heuristics, such as the one that
-+ * guarantees a low latency to soft real-time applications, and a
-+ * hierarchical extension based on H-WF2Q+.
-+ *
-+ * B-WF2Q+ is based on WF2Q+, that is described in [2], together with
-+ * H-WF2Q+, while the augmented tree used to implement B-WF2Q+ with O(log N)
-+ * complexity derives from the one introduced with EEVDF in [3].
-+ *
-+ * [1] P. Valente, A. Avanzini, "Evolution of the BFQ Storage I/O
-+ *   Scheduler", Proceedings of the First Workshop on Mobile System
-+ *   Technologies (MST-2015), May 2015.
-+ *   http://algogroup.unimore.it/people/paolo/disk_sched/mst-2015.pdf
-+ *
-+ * http://algogroup.unimo.it/people/paolo/disk_sched/bf1-v1-suite-results.pdf
-+ *
-+ * [2] Jon C.R. Bennett and H. Zhang, ``Hierarchical Packet Fair Queueing
-+ *     Algorithms,'' IEEE/ACM Transactions on Networking, 5(5):675-689,
-+ *     Oct 1997.
-+ *
-+ * http://www.cs.cmu.edu/~hzhang/papers/TON-97-Oct.ps.gz
-+ *
-+ * [3] I. Stoica and H. Abdel-Wahab, ``Earliest Eligible Virtual Deadline
-+ *     First: A Flexible and Accurate Mechanism for Proportional Share
-+ *     Resource Allocation,'' technical report.
-+ *
-+ * http://www.cs.berkeley.edu/~istoica/papers/eevdf-tr-95.pdf
-+ */
-+#include <linux/module.h>
-+#include <linux/slab.h>
-+#include <linux/blkdev.h>
-+#include <linux/cgroup.h>
-+#include <linux/elevator.h>
-+#include <linux/jiffies.h>
-+#include <linux/rbtree.h>
-+#include <linux/ioprio.h>
-+#include "blk.h"
-+#include "bfq.h"
-+
-+/* Expiration time of sync (0) and async (1) requests, in ns. */
-+static const u64 bfq_fifo_expire[2] = { NSEC_PER_SEC / 4, NSEC_PER_SEC / 8 };
-+
-+/* Maximum backwards seek, in KiB. */
-+static const int bfq_back_max = (16 * 1024);
-+
-+/* Penalty of a backwards seek, in number of sectors. */
-+static const int bfq_back_penalty = 2;
-+
-+/* Idling period duration, in ns. */
-+static u32 bfq_slice_idle = (NSEC_PER_SEC / 125);
-+
-+/* Minimum number of assigned budgets for which stats are safe to compute. */
-+static const int bfq_stats_min_budgets = 194;
-+
-+/* Default maximum budget values, in sectors and number of requests. */
-+static const int bfq_default_max_budget = (16 * 1024);
-+
-+/*
-+ * Async to sync throughput distribution is controlled as follows:
-+ * when an async request is served, the entity is charged the number
-+ * of sectors of the request, multiplied by the factor below
-+ */
-+static const int bfq_async_charge_factor = 10;
-+
-+/* Default timeout values, in jiffies, approximating CFQ defaults. */
-+static const int bfq_timeout = (HZ / 8);
-+
-+static struct kmem_cache *bfq_pool;
-+
-+/* Below this threshold (in ns), we consider thinktime immediate. */
-+#define BFQ_MIN_TT		(2 * NSEC_PER_MSEC)
-+
-+/* hw_tag detection: parallel requests threshold and min samples needed. */
-+#define BFQ_HW_QUEUE_THRESHOLD	4
-+#define BFQ_HW_QUEUE_SAMPLES	32
-+
-+#define BFQQ_SEEK_THR		(sector_t)(8 * 100)
-+#define BFQQ_SECT_THR_NONROT	(sector_t)(2 * 32)
-+#define BFQQ_CLOSE_THR		(sector_t)(8 * 1024)
-+#define BFQQ_SEEKY(bfqq)	(hweight32(bfqq->seek_history) > 32/8)
-+
-+/* Min number of samples required to perform peak-rate update */
-+#define BFQ_RATE_MIN_SAMPLES	32
-+/* Min observation time interval required to perform a peak-rate update (ns) */
-+#define BFQ_RATE_MIN_INTERVAL	(300*NSEC_PER_MSEC)
-+/* Target observation time interval for a peak-rate update (ns) */
-+#define BFQ_RATE_REF_INTERVAL	NSEC_PER_SEC
-+
-+/* Shift used for peak rate fixed precision calculations. */
-+#define BFQ_RATE_SHIFT		16
-+
-+/*
-+ * By default, BFQ computes the duration of the weight raising for
-+ * interactive applications automatically, using the following formula:
-+ * duration = (R / r) * T, where r is the peak rate of the device, and
-+ * R and T are two reference parameters.
-+ * In particular, R is the peak rate of the reference device (see below),
-+ * and T is a reference time: given the systems that are likely to be
-+ * installed on the reference device according to its speed class, T is
-+ * about the maximum time needed, under BFQ and while reading two files in
-+ * parallel, to load typical large applications on these systems.
-+ * In practice, the slower/faster the device at hand is, the more/less it
-+ * takes to load applications with respect to the reference device.
-+ * Accordingly, the longer/shorter BFQ grants weight raising to interactive
-+ * applications.
-+ *
-+ * BFQ uses four different reference pairs (R, T), depending on:
-+ * . whether the device is rotational or non-rotational;
-+ * . whether the device is slow, such as old or portable HDDs, as well as
-+ *   SD cards, or fast, such as newer HDDs and SSDs.
-+ *
-+ * The device's speed class is dynamically (re)detected in
-+ * bfq_update_peak_rate() every time the estimated peak rate is updated.
-+ *
-+ * In the following definitions, R_slow[0]/R_fast[0] and
-+ * T_slow[0]/T_fast[0] are the reference values for a slow/fast
-+ * rotational device, whereas R_slow[1]/R_fast[1] and
-+ * T_slow[1]/T_fast[1] are the reference values for a slow/fast
-+ * non-rotational device. Finally, device_speed_thresh are the
-+ * thresholds used to switch between speed classes. The reference
-+ * rates are not the actual peak rates of the devices used as a
-+ * reference, but slightly lower values. The reason for using these
-+ * slightly lower values is that the peak-rate estimator tends to
-+ * yield slightly lower values than the actual peak rate (it can yield
-+ * the actual peak rate only if there is only one process doing I/O,
-+ * and the process does sequential I/O).
-+ *
-+ * Both the reference peak rates and the thresholds are measured in
-+ * sectors/usec, left-shifted by BFQ_RATE_SHIFT.
-+ */
-+static int R_slow[2] = {1000, 10700};
-+static int R_fast[2] = {14000, 33000};
-+/*
-+ * To improve readability, a conversion function is used to initialize the
-+ * following arrays, which entails that they can be initialized only in a
-+ * function.
-+ */
-+static int T_slow[2];
-+static int T_fast[2];
-+static int device_speed_thresh[2];
-+
-+#define BFQ_SERVICE_TREE_INIT	((struct bfq_service_tree)		\
-+				{ RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 })
-+
-+#define RQ_BIC(rq)		((struct bfq_io_cq *) (rq)->elv.priv[0])
-+#define RQ_BFQQ(rq)		((rq)->elv.priv[1])
-+
-+static void bfq_schedule_dispatch(struct bfq_data *bfqd);
-+
-+#include "bfq-ioc.c"
-+#include "bfq-sched.c"
-+#include "bfq-cgroup-included.c"
-+
-+#define bfq_class_idle(bfqq)	((bfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
-+#define bfq_class_rt(bfqq)	((bfqq)->ioprio_class == IOPRIO_CLASS_RT)
-+
-+#define bfq_sample_valid(samples)	((samples) > 80)
-+
-+/*
-+ * Scheduler run of queue, if there are requests pending and no one in the
-+ * driver that will restart queueing.
-+ */
-+static void bfq_schedule_dispatch(struct bfq_data *bfqd)
-+{
-+	if (bfqd->queued != 0) {
-+		bfq_log(bfqd, "schedule dispatch");
-+		kblockd_schedule_work(&bfqd->unplug_work);
-+	}
-+}
-+
-+/*
-+ * Lifted from AS - choose which of rq1 and rq2 that is best served now.
-+ * We choose the request that is closesr to the head right now.  Distance
-+ * behind the head is penalized and only allowed to a certain extent.
-+ */
-+static struct request *bfq_choose_req(struct bfq_data *bfqd,
-+				      struct request *rq1,
-+				      struct request *rq2,
-+				      sector_t last)
-+{
-+	sector_t s1, s2, d1 = 0, d2 = 0;
-+	unsigned long back_max;
-+#define BFQ_RQ1_WRAP	0x01 /* request 1 wraps */
-+#define BFQ_RQ2_WRAP	0x02 /* request 2 wraps */
-+	unsigned int wrap = 0; /* bit mask: requests behind the disk head? */
-+
-+	if (!rq1 || rq1 == rq2)
-+		return rq2;
-+	if (!rq2)
-+		return rq1;
-+
-+	if (rq_is_sync(rq1) && !rq_is_sync(rq2))
-+		return rq1;
-+	else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
-+		return rq2;
-+	if ((rq1->cmd_flags & REQ_META) && !(rq2->cmd_flags & REQ_META))
-+		return rq1;
-+	else if ((rq2->cmd_flags & REQ_META) && !(rq1->cmd_flags & REQ_META))
-+		return rq2;
-+
-+	s1 = blk_rq_pos(rq1);
-+	s2 = blk_rq_pos(rq2);
-+
-+	/*
-+	 * By definition, 1KiB is 2 sectors.
-+	 */
-+	back_max = bfqd->bfq_back_max * 2;
-+
-+	/*
-+	 * Strict one way elevator _except_ in the case where we allow
-+	 * short backward seeks which are biased as twice the cost of a
-+	 * similar forward seek.
-+	 */
-+	if (s1 >= last)
-+		d1 = s1 - last;
-+	else if (s1 + back_max >= last)
-+		d1 = (last - s1) * bfqd->bfq_back_penalty;
-+	else
-+		wrap |= BFQ_RQ1_WRAP;
-+
-+	if (s2 >= last)
-+		d2 = s2 - last;
-+	else if (s2 + back_max >= last)
-+		d2 = (last - s2) * bfqd->bfq_back_penalty;
-+	else
-+		wrap |= BFQ_RQ2_WRAP;
-+
-+	/* Found required data */
-+
-+	/*
-+	 * By doing switch() on the bit mask "wrap" we avoid having to
-+	 * check two variables for all permutations: --> faster!
-+	 */
-+	switch (wrap) {
-+	case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
-+		if (d1 < d2)
-+			return rq1;
-+		else if (d2 < d1)
-+			return rq2;
-+
-+		if (s1 >= s2)
-+			return rq1;
-+		else
-+			return rq2;
-+
-+	case BFQ_RQ2_WRAP:
-+		return rq1;
-+	case BFQ_RQ1_WRAP:
-+		return rq2;
-+	case (BFQ_RQ1_WRAP|BFQ_RQ2_WRAP): /* both rqs wrapped */
-+	default:
-+		/*
-+		 * Since both rqs are wrapped,
-+		 * start with the one that's further behind head
-+		 * (--> only *one* back seek required),
-+		 * since back seek takes more time than forward.
-+		 */
-+		if (s1 <= s2)
-+			return rq1;
-+		else
-+			return rq2;
-+	}
-+}
-+
-+static struct bfq_queue *
-+bfq_rq_pos_tree_lookup(struct bfq_data *bfqd, struct rb_root *root,
-+		     sector_t sector, struct rb_node **ret_parent,
-+		     struct rb_node ***rb_link)
-+{
-+	struct rb_node **p, *parent;
-+	struct bfq_queue *bfqq = NULL;
-+
-+	parent = NULL;
-+	p = &root->rb_node;
-+	while (*p) {
-+		struct rb_node **n;
-+
-+		parent = *p;
-+		bfqq = rb_entry(parent, struct bfq_queue, pos_node);
-+
-+		/*
-+		 * Sort strictly based on sector. Smallest to the left,
-+		 * largest to the right.
-+		 */
-+		if (sector > blk_rq_pos(bfqq->next_rq))
-+			n = &(*p)->rb_right;
-+		else if (sector < blk_rq_pos(bfqq->next_rq))
-+			n = &(*p)->rb_left;
-+		else
-+			break;
-+		p = n;
-+		bfqq = NULL;
-+	}
-+
-+	*ret_parent = parent;
-+	if (rb_link)
-+		*rb_link = p;
-+
-+	bfq_log(bfqd, "rq_pos_tree_lookup %llu: returning %d",
-+		(unsigned long long) sector,
-+		bfqq ? bfqq->pid : 0);
-+
-+	return bfqq;
-+}
-+
-+static void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	struct rb_node **p, *parent;
-+	struct bfq_queue *__bfqq;
-+
-+	if (bfqq->pos_root) {
-+		rb_erase(&bfqq->pos_node, bfqq->pos_root);
-+		bfqq->pos_root = NULL;
-+	}
-+
-+	if (bfq_class_idle(bfqq))
-+		return;
-+	if (!bfqq->next_rq)
-+		return;
-+
-+	bfqq->pos_root = &bfq_bfqq_to_bfqg(bfqq)->rq_pos_tree;
-+	__bfqq = bfq_rq_pos_tree_lookup(bfqd, bfqq->pos_root,
-+			blk_rq_pos(bfqq->next_rq), &parent, &p);
-+	if (!__bfqq) {
-+		rb_link_node(&bfqq->pos_node, parent, p);
-+		rb_insert_color(&bfqq->pos_node, bfqq->pos_root);
-+	} else
-+		bfqq->pos_root = NULL;
-+}
-+
-+/*
-+ * Tell whether there are active queues or groups with differentiated weights.
-+ */
-+static bool bfq_differentiated_weights(struct bfq_data *bfqd)
-+{
-+	/*
-+	 * For weights to differ, at least one of the trees must contain
-+	 * at least two nodes.
-+	 */
-+	return (!RB_EMPTY_ROOT(&bfqd->queue_weights_tree) &&
-+		(bfqd->queue_weights_tree.rb_node->rb_left ||
-+		 bfqd->queue_weights_tree.rb_node->rb_right)
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	       ) ||
-+	       (!RB_EMPTY_ROOT(&bfqd->group_weights_tree) &&
-+		(bfqd->group_weights_tree.rb_node->rb_left ||
-+		 bfqd->group_weights_tree.rb_node->rb_right)
-+#endif
-+	       );
-+}
-+
-+/*
-+ * The following function returns true if every queue must receive the
-+ * same share of the throughput (this condition is used when deciding
-+ * whether idling may be disabled, see the comments in the function
-+ * bfq_bfqq_may_idle()).
-+ *
-+ * Such a scenario occurs when:
-+ * 1) all active queues have the same weight,
-+ * 2) all active groups at the same level in the groups tree have the same
-+ *    weight,
-+ * 3) all active groups at the same level in the groups tree have the same
-+ *    number of children.
-+ *
-+ * Unfortunately, keeping the necessary state for evaluating exactly the
-+ * above symmetry conditions would be quite complex and time-consuming.
-+ * Therefore this function evaluates, instead, the following stronger
-+ * sub-conditions, for which it is much easier to maintain the needed
-+ * state:
-+ * 1) all active queues have the same weight,
-+ * 2) all active groups have the same weight,
-+ * 3) all active groups have at most one active child each.
-+ * In particular, the last two conditions are always true if hierarchical
-+ * support and the cgroups interface are not enabled, thus no state needs
-+ * to be maintained in this case.
-+ */
-+static bool bfq_symmetric_scenario(struct bfq_data *bfqd)
-+{
-+	return !bfq_differentiated_weights(bfqd);
-+}
-+
-+/*
-+ * If the weight-counter tree passed as input contains no counter for
-+ * the weight of the input entity, then add that counter; otherwise just
-+ * increment the existing counter.
-+ *
-+ * Note that weight-counter trees contain few nodes in mostly symmetric
-+ * scenarios. For example, if all queues have the same weight, then the
-+ * weight-counter tree for the queues may contain at most one node.
-+ * This holds even if low_latency is on, because weight-raised queues
-+ * are not inserted in the tree.
-+ * In most scenarios, the rate at which nodes are created/destroyed
-+ * should be low too.
-+ */
-+static void bfq_weights_tree_add(struct bfq_data *bfqd,
-+				 struct bfq_entity *entity,
-+				 struct rb_root *root)
-+{
-+	struct rb_node **new = &(root->rb_node), *parent = NULL;
-+
-+	/*
-+	 * Do not insert if the entity is already associated with a
-+	 * counter, which happens if:
-+	 *   1) the entity is associated with a queue,
-+	 *   2) a request arrival has caused the queue to become both
-+	 *      non-weight-raised, and hence change its weight, and
-+	 *      backlogged; in this respect, each of the two events
-+	 *      causes an invocation of this function,
-+	 *   3) this is the invocation of this function caused by the
-+	 *      second event. This second invocation is actually useless,
-+	 *      and we handle this fact by exiting immediately. More
-+	 *      efficient or clearer solutions might possibly be adopted.
-+	 */
-+	if (entity->weight_counter)
-+		return;
-+
-+	while (*new) {
-+		struct bfq_weight_counter *__counter = container_of(*new,
-+						struct bfq_weight_counter,
-+						weights_node);
-+		parent = *new;
-+
-+		if (entity->weight == __counter->weight) {
-+			entity->weight_counter = __counter;
-+			goto inc_counter;
-+		}
-+		if (entity->weight < __counter->weight)
-+			new = &((*new)->rb_left);
-+		else
-+			new = &((*new)->rb_right);
-+	}
-+
-+	entity->weight_counter = kzalloc(sizeof(struct bfq_weight_counter),
-+					 GFP_ATOMIC);
-+
-+	/*
-+	 * In the unlucky event of an allocation failure, we just
-+	 * exit. This will cause the weight of entity to not be
-+	 * considered in bfq_differentiated_weights, which, in its
-+	 * turn, causes the scenario to be deemed wrongly symmetric in
-+	 * case entity's weight would have been the only weight making
-+	 * the scenario asymmetric. On the bright side, no unbalance
-+	 * will however occur when entity becomes inactive again (the
-+	 * invocation of this function is triggered by an activation
-+	 * of entity). In fact, bfq_weights_tree_remove does nothing
-+	 * if !entity->weight_counter.
-+	 */
-+	if (unlikely(!entity->weight_counter))
-+		return;
-+
-+	entity->weight_counter->weight = entity->weight;
-+	rb_link_node(&entity->weight_counter->weights_node, parent, new);
-+	rb_insert_color(&entity->weight_counter->weights_node, root);
-+
-+inc_counter:
-+	entity->weight_counter->num_active++;
-+}
-+
-+/*
-+ * Decrement the weight counter associated with the entity, and, if the
-+ * counter reaches 0, remove the counter from the tree.
-+ * See the comments to the function bfq_weights_tree_add() for considerations
-+ * about overhead.
-+ */
-+static void bfq_weights_tree_remove(struct bfq_data *bfqd,
-+				    struct bfq_entity *entity,
-+				    struct rb_root *root)
-+{
-+	if (!entity->weight_counter)
-+		return;
-+
-+	BUG_ON(RB_EMPTY_ROOT(root));
-+	BUG_ON(entity->weight_counter->weight != entity->weight);
-+
-+	BUG_ON(!entity->weight_counter->num_active);
-+	entity->weight_counter->num_active--;
-+	if (entity->weight_counter->num_active > 0)
-+		goto reset_entity_pointer;
-+
-+	rb_erase(&entity->weight_counter->weights_node, root);
-+	kfree(entity->weight_counter);
-+
-+reset_entity_pointer:
-+	entity->weight_counter = NULL;
-+}
-+
-+/*
-+ * Return expired entry, or NULL to just start from scratch in rbtree.
-+ */
-+static struct request *bfq_check_fifo(struct bfq_queue *bfqq,
-+				      struct request *last)
-+{
-+	struct request *rq;
-+
-+	if (bfq_bfqq_fifo_expire(bfqq))
-+		return NULL;
-+
-+	bfq_mark_bfqq_fifo_expire(bfqq);
-+
-+	rq = rq_entry_fifo(bfqq->fifo.next);
-+
-+	if (rq == last || ktime_get_ns() < rq->fifo_time)
-+		return NULL;
-+
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "check_fifo: returned %p", rq);
-+	BUG_ON(RB_EMPTY_NODE(&rq->rb_node));
-+	return rq;
-+}
-+
-+static struct request *bfq_find_next_rq(struct bfq_data *bfqd,
-+					struct bfq_queue *bfqq,
-+					struct request *last)
-+{
-+	struct rb_node *rbnext = rb_next(&last->rb_node);
-+	struct rb_node *rbprev = rb_prev(&last->rb_node);
-+	struct request *next, *prev = NULL;
-+
-+	BUG_ON(list_empty(&bfqq->fifo));
-+
-+	/* Follow expired path, else get first next available. */
-+	next = bfq_check_fifo(bfqq, last);
-+	if (next) {
-+		BUG_ON(next == last);
-+		return next;
-+	}
-+
-+	BUG_ON(RB_EMPTY_NODE(&last->rb_node));
-+
-+	if (rbprev)
-+		prev = rb_entry_rq(rbprev);
-+
-+	if (rbnext)
-+		next = rb_entry_rq(rbnext);
-+	else {
-+		rbnext = rb_first(&bfqq->sort_list);
-+		if (rbnext && rbnext != &last->rb_node)
-+			next = rb_entry_rq(rbnext);
-+	}
-+
-+	return bfq_choose_req(bfqd, next, prev, blk_rq_pos(last));
-+}
-+
-+/* see the definition of bfq_async_charge_factor for details */
-+static unsigned long bfq_serv_to_charge(struct request *rq,
-+					struct bfq_queue *bfqq)
-+{
-+	if (bfq_bfqq_sync(bfqq) || bfqq->wr_coeff > 1)
-+		return blk_rq_sectors(rq);
-+
-+	/*
-+	 * If there are no weight-raised queues, then amplify service
-+	 * by just the async charge factor; otherwise amplify service
-+	 * by twice the async charge factor, to further reduce latency
-+	 * for weight-raised queues.
-+	 */
-+	if (bfqq->bfqd->wr_busy_queues == 0)
-+		return blk_rq_sectors(rq) * bfq_async_charge_factor;
-+
-+	return blk_rq_sectors(rq) * 2 * bfq_async_charge_factor;
-+}
-+
-+/**
-+ * bfq_updated_next_req - update the queue after a new next_rq selection.
-+ * @bfqd: the device data the queue belongs to.
-+ * @bfqq: the queue to update.
-+ *
-+ * If the first request of a queue changes we make sure that the queue
-+ * has enough budget to serve at least its first request (if the
-+ * request has grown).  We do this because if the queue has not enough
-+ * budget for its first request, it has to go through two dispatch
-+ * rounds to actually get it dispatched.
-+ */
-+static void bfq_updated_next_req(struct bfq_data *bfqd,
-+				 struct bfq_queue *bfqq)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+	struct bfq_service_tree *st = bfq_entity_service_tree(entity);
-+	struct request *next_rq = bfqq->next_rq;
-+	unsigned long new_budget;
-+
-+	if (!next_rq)
-+		return;
-+
-+	if (bfqq == bfqd->in_service_queue)
-+		/*
-+		 * In order not to break guarantees, budgets cannot be
-+		 * changed after an entity has been selected.
-+		 */
-+		return;
-+
-+	BUG_ON(entity->tree != &st->active);
-+	BUG_ON(entity == entity->sched_data->in_service_entity);
-+
-+	new_budget = max_t(unsigned long, bfqq->max_budget,
-+			   bfq_serv_to_charge(next_rq, bfqq));
-+	if (entity->budget != new_budget) {
-+		entity->budget = new_budget;
-+		bfq_log_bfqq(bfqd, bfqq, "updated next rq: new budget %lu",
-+					 new_budget);
-+		bfq_requeue_bfqq(bfqd, bfqq);
-+	}
-+}
-+
-+static unsigned int bfq_wr_duration(struct bfq_data *bfqd)
-+{
-+	u64 dur;
-+
-+	if (bfqd->bfq_wr_max_time > 0)
-+		return bfqd->bfq_wr_max_time;
-+
-+	dur = bfqd->RT_prod;
-+	do_div(dur, bfqd->peak_rate);
-+
-+	/*
-+	 * Limit duration between 3 and 13 seconds. Tests show that
-+	 * higher values than 13 seconds often yield the opposite of
-+	 * the desired result, i.e., worsen responsiveness by letting
-+	 * non-interactive and non-soft-real-time applications
-+	 * preserve weight raising for a too long time interval.
-+	 *
-+	 * On the other end, lower values than 3 seconds make it
-+	 * difficult for most interactive tasks to complete their jobs
-+	 * before weight-raising finishes.
-+	 */
-+	if (dur > msecs_to_jiffies(13000))
-+		dur = msecs_to_jiffies(13000);
-+	else if (dur < msecs_to_jiffies(3000))
-+		dur = msecs_to_jiffies(3000);
-+
-+	return dur;
-+}
-+
-+static void
-+bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_data *bfqd,
-+		      struct bfq_io_cq *bic, bool bfq_already_existing)
-+{
-+	unsigned int old_wr_coeff;
-+	bool busy = bfq_already_existing && bfq_bfqq_busy(bfqq);
-+
-+	if (bic->saved_idle_window)
-+		bfq_mark_bfqq_idle_window(bfqq);
-+	else
-+		bfq_clear_bfqq_idle_window(bfqq);
-+
-+	if (bic->saved_IO_bound)
-+		bfq_mark_bfqq_IO_bound(bfqq);
-+	else
-+		bfq_clear_bfqq_IO_bound(bfqq);
-+
-+	if (unlikely(busy))
-+		old_wr_coeff = bfqq->wr_coeff;
-+
-+	bfqq->wr_coeff = bic->saved_wr_coeff;
-+	bfqq->wr_start_at_switch_to_srt = bic->saved_wr_start_at_switch_to_srt;
-+	BUG_ON(time_is_after_jiffies(bfqq->wr_start_at_switch_to_srt));
-+	bfqq->last_wr_start_finish = bic->saved_last_wr_start_finish;
-+	bfqq->wr_cur_max_time = bic->saved_wr_cur_max_time;
-+	BUG_ON(time_is_after_jiffies(bfqq->last_wr_start_finish));
-+
-+	if (bfqq->wr_coeff > 1 && (bfq_bfqq_in_large_burst(bfqq) ||
-+				   time_is_before_jiffies(bfqq->last_wr_start_finish +
-+							  bfqq->wr_cur_max_time))) {
-+		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			     "resume state: switching off wr (%lu + %lu < %lu)",
-+			     bfqq->last_wr_start_finish, bfqq->wr_cur_max_time,
-+			     jiffies);
-+
-+		bfqq->wr_coeff = 1;
-+	}
-+
-+	/* make sure weight will be updated, however we got here */
-+	bfqq->entity.prio_changed = 1;
-+
-+	if (likely(!busy))
-+		return;
-+
-+	if (old_wr_coeff == 1 && bfqq->wr_coeff > 1) {
-+		bfqd->wr_busy_queues++;
-+		BUG_ON(bfqd->wr_busy_queues > bfqd->busy_queues);
-+	} else if (old_wr_coeff > 1 && bfqq->wr_coeff == 1) {
-+		bfqd->wr_busy_queues--;
-+		BUG_ON(bfqd->wr_busy_queues < 0);
-+	}
-+}
-+
-+static int bfqq_process_refs(struct bfq_queue *bfqq)
-+{
-+	int process_refs, io_refs;
-+
-+	lockdep_assert_held(bfqq->bfqd->queue->queue_lock);
-+
-+	io_refs = bfqq->allocated[READ] + bfqq->allocated[WRITE];
-+	process_refs = bfqq->ref - io_refs - bfqq->entity.on_st;
-+	BUG_ON(process_refs < 0);
-+	return process_refs;
-+}
-+
-+/* Empty burst list and add just bfqq (see comments to bfq_handle_burst) */
-+static void bfq_reset_burst_list(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	struct bfq_queue *item;
-+	struct hlist_node *n;
-+
-+	hlist_for_each_entry_safe(item, n, &bfqd->burst_list, burst_list_node)
-+		hlist_del_init(&item->burst_list_node);
-+	hlist_add_head(&bfqq->burst_list_node, &bfqd->burst_list);
-+	bfqd->burst_size = 1;
-+	bfqd->burst_parent_entity = bfqq->entity.parent;
-+}
-+
-+/* Add bfqq to the list of queues in current burst (see bfq_handle_burst) */
-+static void bfq_add_to_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	/* Increment burst size to take into account also bfqq */
-+	bfqd->burst_size++;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "add_to_burst %d", bfqd->burst_size);
-+
-+	BUG_ON(bfqd->burst_size > bfqd->bfq_large_burst_thresh);
-+
-+	if (bfqd->burst_size == bfqd->bfq_large_burst_thresh) {
-+		struct bfq_queue *pos, *bfqq_item;
-+		struct hlist_node *n;
-+
-+		/*
-+		 * Enough queues have been activated shortly after each
-+		 * other to consider this burst as large.
-+		 */
-+		bfqd->large_burst = true;
-+		bfq_log_bfqq(bfqd, bfqq, "add_to_burst: large burst started");
-+
-+		/*
-+		 * We can now mark all queues in the burst list as
-+		 * belonging to a large burst.
-+		 */
-+		hlist_for_each_entry(bfqq_item, &bfqd->burst_list,
-+				     burst_list_node) {
-+			bfq_mark_bfqq_in_large_burst(bfqq_item);
-+			bfq_log_bfqq(bfqd, bfqq_item, "marked in large burst");
-+		}
-+		bfq_mark_bfqq_in_large_burst(bfqq);
-+		bfq_log_bfqq(bfqd, bfqq, "marked in large burst");
-+
-+		/*
-+		 * From now on, and until the current burst finishes, any
-+		 * new queue being activated shortly after the last queue
-+		 * was inserted in the burst can be immediately marked as
-+		 * belonging to a large burst. So the burst list is not
-+		 * needed any more. Remove it.
-+		 */
-+		hlist_for_each_entry_safe(pos, n, &bfqd->burst_list,
-+					  burst_list_node)
-+			hlist_del_init(&pos->burst_list_node);
-+	} else /*
-+		* Burst not yet large: add bfqq to the burst list. Do
-+		* not increment the ref counter for bfqq, because bfqq
-+		* is removed from the burst list before freeing bfqq
-+		* in put_queue.
-+		*/
-+		hlist_add_head(&bfqq->burst_list_node, &bfqd->burst_list);
-+}
-+
-+/*
-+ * If many queues belonging to the same group happen to be created
-+ * shortly after each other, then the processes associated with these
-+ * queues have typically a common goal. In particular, bursts of queue
-+ * creations are usually caused by services or applications that spawn
-+ * many parallel threads/processes. Examples are systemd during boot,
-+ * or git grep. To help these processes get their job done as soon as
-+ * possible, it is usually better to not grant either weight-raising
-+ * or device idling to their queues.
-+ *
-+ * In this comment we describe, firstly, the reasons why this fact
-+ * holds, and, secondly, the next function, which implements the main
-+ * steps needed to properly mark these queues so that they can then be
-+ * treated in a different way.
-+ *
-+ * The above services or applications benefit mostly from a high
-+ * throughput: the quicker the requests of the activated queues are
-+ * cumulatively served, the sooner the target job of these queues gets
-+ * completed. As a consequence, weight-raising any of these queues,
-+ * which also implies idling the device for it, is almost always
-+ * counterproductive. In most cases it just lowers throughput.
-+ *
-+ * On the other hand, a burst of queue creations may be caused also by
-+ * the start of an application that does not consist of a lot of
-+ * parallel I/O-bound threads. In fact, with a complex application,
-+ * several short processes may need to be executed to start-up the
-+ * application. In this respect, to start an application as quickly as
-+ * possible, the best thing to do is in any case to privilege the I/O
-+ * related to the application with respect to all other
-+ * I/O. Therefore, the best strategy to start as quickly as possible
-+ * an application that causes a burst of queue creations is to
-+ * weight-raise all the queues created during the burst. This is the
-+ * exact opposite of the best strategy for the other type of bursts.
-+ *
-+ * In the end, to take the best action for each of the two cases, the
-+ * two types of bursts need to be distinguished. Fortunately, this
-+ * seems relatively easy, by looking at the sizes of the bursts. In
-+ * particular, we found a threshold such that only bursts with a
-+ * larger size than that threshold are apparently caused by
-+ * services or commands such as systemd or git grep. For brevity,
-+ * hereafter we call just 'large' these bursts. BFQ *does not*
-+ * weight-raise queues whose creation occurs in a large burst. In
-+ * addition, for each of these queues BFQ performs or does not perform
-+ * idling depending on which choice boosts the throughput more. The
-+ * exact choice depends on the device and request pattern at
-+ * hand.
-+ *
-+ * Unfortunately, false positives may occur while an interactive task
-+ * is starting (e.g., an application is being started). The
-+ * consequence is that the queues associated with the task do not
-+ * enjoy weight raising as expected. Fortunately these false positives
-+ * are very rare. They typically occur if some service happens to
-+ * start doing I/O exactly when the interactive task starts.
-+ *
-+ * Turning back to the next function, it implements all the steps
-+ * needed to detect the occurrence of a large burst and to properly
-+ * mark all the queues belonging to it (so that they can then be
-+ * treated in a different way). This goal is achieved by maintaining a
-+ * "burst list" that holds, temporarily, the queues that belong to the
-+ * burst in progress. The list is then used to mark these queues as
-+ * belonging to a large burst if the burst does become large. The main
-+ * steps are the following.
-+ *
-+ * . when the very first queue is created, the queue is inserted into the
-+ *   list (as it could be the first queue in a possible burst)
-+ *
-+ * . if the current burst has not yet become large, and a queue Q that does
-+ *   not yet belong to the burst is activated shortly after the last time
-+ *   at which a new queue entered the burst list, then the function appends
-+ *   Q to the burst list
-+ *
-+ * . if, as a consequence of the previous step, the burst size reaches
-+ *   the large-burst threshold, then
-+ *
-+ *     . all the queues in the burst list are marked as belonging to a
-+ *       large burst
-+ *
-+ *     . the burst list is deleted; in fact, the burst list already served
-+ *       its purpose (keeping temporarily track of the queues in a burst,
-+ *       so as to be able to mark them as belonging to a large burst in the
-+ *       previous sub-step), and now is not needed any more
-+ *
-+ *     . the device enters a large-burst mode
-+ *
-+ * . if a queue Q that does not belong to the burst is created while
-+ *   the device is in large-burst mode and shortly after the last time
-+ *   at which a queue either entered the burst list or was marked as
-+ *   belonging to the current large burst, then Q is immediately marked
-+ *   as belonging to a large burst.
-+ *
-+ * . if a queue Q that does not belong to the burst is created a while
-+ *   later, i.e., not shortly after, than the last time at which a queue
-+ *   either entered the burst list or was marked as belonging to the
-+ *   current large burst, then the current burst is deemed as finished and:
-+ *
-+ *        . the large-burst mode is reset if set
-+ *
-+ *        . the burst list is emptied
-+ *
-+ *        . Q is inserted in the burst list, as Q may be the first queue
-+ *          in a possible new burst (then the burst list contains just Q
-+ *          after this step).
-+ */
-+static void bfq_handle_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	/*
-+	 * If bfqq is already in the burst list or is part of a large
-+	 * burst, or finally has just been split, then there is
-+	 * nothing else to do.
-+	 */
-+	if (!hlist_unhashed(&bfqq->burst_list_node) ||
-+	    bfq_bfqq_in_large_burst(bfqq) ||
-+	    time_is_after_eq_jiffies(bfqq->split_time +
-+				     msecs_to_jiffies(10)))
-+		return;
-+
-+	/*
-+	 * If bfqq's creation happens late enough, or bfqq belongs to
-+	 * a different group than the burst group, then the current
-+	 * burst is finished, and related data structures must be
-+	 * reset.
-+	 *
-+	 * In this respect, consider the special case where bfqq is
-+	 * the very first queue created after BFQ is selected for this
-+	 * device. In this case, last_ins_in_burst and
-+	 * burst_parent_entity are not yet significant when we get
-+	 * here. But it is easy to verify that, whether or not the
-+	 * following condition is true, bfqq will end up being
-+	 * inserted into the burst list. In particular the list will
-+	 * happen to contain only bfqq. And this is exactly what has
-+	 * to happen, as bfqq may be the first queue of the first
-+	 * burst.
-+	 */
-+	if (time_is_before_jiffies(bfqd->last_ins_in_burst +
-+	    bfqd->bfq_burst_interval) ||
-+	    bfqq->entity.parent != bfqd->burst_parent_entity) {
-+		bfqd->large_burst = false;
-+		bfq_reset_burst_list(bfqd, bfqq);
-+		bfq_log_bfqq(bfqd, bfqq,
-+			"handle_burst: late activation or different group");
-+		goto end;
-+	}
-+
-+	/*
-+	 * If we get here, then bfqq is being activated shortly after the
-+	 * last queue. So, if the current burst is also large, we can mark
-+	 * bfqq as belonging to this large burst immediately.
-+	 */
-+	if (bfqd->large_burst) {
-+		bfq_log_bfqq(bfqd, bfqq, "handle_burst: marked in burst");
-+		bfq_mark_bfqq_in_large_burst(bfqq);
-+		goto end;
-+	}
-+
-+	/*
-+	 * If we get here, then a large-burst state has not yet been
-+	 * reached, but bfqq is being activated shortly after the last
-+	 * queue. Then we add bfqq to the burst.
-+	 */
-+	bfq_add_to_burst(bfqd, bfqq);
-+end:
-+	/*
-+	 * At this point, bfqq either has been added to the current
-+	 * burst or has caused the current burst to terminate and a
-+	 * possible new burst to start. In particular, in the second
-+	 * case, bfqq has become the first queue in the possible new
-+	 * burst.  In both cases last_ins_in_burst needs to be moved
-+	 * forward.
-+	 */
-+	bfqd->last_ins_in_burst = jiffies;
-+
-+}
-+
-+static int bfq_bfqq_budget_left(struct bfq_queue *bfqq)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+
-+	return entity->budget - entity->service;
-+}
-+
-+/*
-+ * If enough samples have been computed, return the current max budget
-+ * stored in bfqd, which is dynamically updated according to the
-+ * estimated disk peak rate; otherwise return the default max budget
-+ */
-+static int bfq_max_budget(struct bfq_data *bfqd)
-+{
-+	if (bfqd->budgets_assigned < bfq_stats_min_budgets)
-+		return bfq_default_max_budget;
-+	else
-+		return bfqd->bfq_max_budget;
-+}
-+
-+/*
-+ * Return min budget, which is a fraction of the current or default
-+ * max budget (trying with 1/32)
-+ */
-+static int bfq_min_budget(struct bfq_data *bfqd)
-+{
-+	if (bfqd->budgets_assigned < bfq_stats_min_budgets)
-+		return bfq_default_max_budget / 32;
-+	else
-+		return bfqd->bfq_max_budget / 32;
-+}
-+
-+static void bfq_bfqq_expire(struct bfq_data *bfqd,
-+			    struct bfq_queue *bfqq,
-+			    bool compensate,
-+			    enum bfqq_expiration reason);
-+
-+/*
-+ * The next function, invoked after the input queue bfqq switches from
-+ * idle to busy, updates the budget of bfqq. The function also tells
-+ * whether the in-service queue should be expired, by returning
-+ * true. The purpose of expiring the in-service queue is to give bfqq
-+ * the chance to possibly preempt the in-service queue, and the reason
-+ * for preempting the in-service queue is to achieve one of the two
-+ * goals below.
-+ *
-+ * 1. Guarantee to bfqq its reserved bandwidth even if bfqq has
-+ * expired because it has remained idle. In particular, bfqq may have
-+ * expired for one of the following two reasons:
-+ *
-+ * - BFQ_BFQQ_NO_MORE_REQUEST bfqq did not enjoy any device idling and
-+ *   did not make it to issue a new request before its last request
-+ *   was served;
-+ *
-+ * - BFQ_BFQQ_TOO_IDLE bfqq did enjoy device idling, but did not issue
-+ *   a new request before the expiration of the idling-time.
-+ *
-+ * Even if bfqq has expired for one of the above reasons, the process
-+ * associated with the queue may be however issuing requests greedily,
-+ * and thus be sensitive to the bandwidth it receives (bfqq may have
-+ * remained idle for other reasons: CPU high load, bfqq not enjoying
-+ * idling, I/O throttling somewhere in the path from the process to
-+ * the I/O scheduler, ...). But if, after every expiration for one of
-+ * the above two reasons, bfqq has to wait for the service of at least
-+ * one full budget of another queue before being served again, then
-+ * bfqq is likely to get a much lower bandwidth or resource time than
-+ * its reserved ones. To address this issue, two countermeasures need
-+ * to be taken.
-+ *
-+ * First, the budget and the timestamps of bfqq need to be updated in
-+ * a special way on bfqq reactivation: they need to be updated as if
-+ * bfqq did not remain idle and did not expire. In fact, if they are
-+ * computed as if bfqq expired and remained idle until reactivation,
-+ * then the process associated with bfqq is treated as if, instead of
-+ * being greedy, it stopped issuing requests when bfqq remained idle,
-+ * and restarts issuing requests only on this reactivation. In other
-+ * words, the scheduler does not help the process recover the "service
-+ * hole" between bfqq expiration and reactivation. As a consequence,
-+ * the process receives a lower bandwidth than its reserved one. In
-+ * contrast, to recover this hole, the budget must be updated as if
-+ * bfqq was not expired at all before this reactivation, i.e., it must
-+ * be set to the value of the remaining budget when bfqq was
-+ * expired. Along the same line, timestamps need to be assigned the
-+ * value they had the last time bfqq was selected for service, i.e.,
-+ * before last expiration. Thus timestamps need to be back-shifted
-+ * with respect to their normal computation (see [1] for more details
-+ * on this tricky aspect).
-+ *
-+ * Secondly, to allow the process to recover the hole, the in-service
-+ * queue must be expired too, to give bfqq the chance to preempt it
-+ * immediately. In fact, if bfqq has to wait for a full budget of the
-+ * in-service queue to be completed, then it may become impossible to
-+ * let the process recover the hole, even if the back-shifted
-+ * timestamps of bfqq are lower than those of the in-service queue. If
-+ * this happens for most or all of the holes, then the process may not
-+ * receive its reserved bandwidth. In this respect, it is worth noting
-+ * that, being the service of outstanding requests unpreemptible, a
-+ * little fraction of the holes may however be unrecoverable, thereby
-+ * causing a little loss of bandwidth.
-+ *
-+ * The last important point is detecting whether bfqq does need this
-+ * bandwidth recovery. In this respect, the next function deems the
-+ * process associated with bfqq greedy, and thus allows it to recover
-+ * the hole, if: 1) the process is waiting for the arrival of a new
-+ * request (which implies that bfqq expired for one of the above two
-+ * reasons), and 2) such a request has arrived soon. The first
-+ * condition is controlled through the flag non_blocking_wait_rq,
-+ * while the second through the flag arrived_in_time. If both
-+ * conditions hold, then the function computes the budget in the
-+ * above-described special way, and signals that the in-service queue
-+ * should be expired. Timestamp back-shifting is done later in
-+ * __bfq_activate_entity.
-+ *
-+ * 2. Reduce latency. Even if timestamps are not backshifted to let
-+ * the process associated with bfqq recover a service hole, bfqq may
-+ * however happen to have, after being (re)activated, a lower finish
-+ * timestamp than the in-service queue.  That is, the next budget of
-+ * bfqq may have to be completed before the one of the in-service
-+ * queue. If this is the case, then preempting the in-service queue
-+ * allows this goal to be achieved, apart from the unpreemptible,
-+ * outstanding requests mentioned above.
-+ *
-+ * Unfortunately, regardless of which of the above two goals one wants
-+ * to achieve, service trees need first to be updated to know whether
-+ * the in-service queue must be preempted. To have service trees
-+ * correctly updated, the in-service queue must be expired and
-+ * rescheduled, and bfqq must be scheduled too. This is one of the
-+ * most costly operations (in future versions, the scheduling
-+ * mechanism may be re-designed in such a way to make it possible to
-+ * know whether preemption is needed without needing to update service
-+ * trees). In addition, queue preemptions almost always cause random
-+ * I/O, and thus loss of throughput. Because of these facts, the next
-+ * function adopts the following simple scheme to avoid both costly
-+ * operations and too frequent preemptions: it requests the expiration
-+ * of the in-service queue (unconditionally) only for queues that need
-+ * to recover a hole, or that either are weight-raised or deserve to
-+ * be weight-raised.
-+ */
-+static bool bfq_bfqq_update_budg_for_activation(struct bfq_data *bfqd,
-+						struct bfq_queue *bfqq,
-+						bool arrived_in_time,
-+						bool wr_or_deserves_wr)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+
-+	if (bfq_bfqq_non_blocking_wait_rq(bfqq) && arrived_in_time) {
-+		/*
-+		 * We do not clear the flag non_blocking_wait_rq here, as
-+		 * the latter is used in bfq_activate_bfqq to signal
-+		 * that timestamps need to be back-shifted (and is
-+		 * cleared right after).
-+		 */
-+
-+		/*
-+		 * In next assignment we rely on that either
-+		 * entity->service or entity->budget are not updated
-+		 * on expiration if bfqq is empty (see
-+		 * __bfq_bfqq_recalc_budget). Thus both quantities
-+		 * remain unchanged after such an expiration, and the
-+		 * following statement therefore assigns to
-+		 * entity->budget the remaining budget on such an
-+		 * expiration. For clarity, entity->service is not
-+		 * updated on expiration in any case, and, in normal
-+		 * operation, is reset only when bfqq is selected for
-+		 * service (see bfq_get_next_queue).
-+		 */
-+		BUG_ON(bfqq->max_budget < 0);
-+		entity->budget = min_t(unsigned long,
-+				       bfq_bfqq_budget_left(bfqq),
-+				       bfqq->max_budget);
-+
-+		BUG_ON(entity->budget < 0);
-+		return true;
-+	}
-+
-+	BUG_ON(bfqq->max_budget < 0);
-+	entity->budget = max_t(unsigned long, bfqq->max_budget,
-+			       bfq_serv_to_charge(bfqq->next_rq, bfqq));
-+	BUG_ON(entity->budget < 0);
-+
-+	bfq_clear_bfqq_non_blocking_wait_rq(bfqq);
-+	return wr_or_deserves_wr;
-+}
-+
-+static void bfq_update_bfqq_wr_on_rq_arrival(struct bfq_data *bfqd,
-+					     struct bfq_queue *bfqq,
-+					     unsigned int old_wr_coeff,
-+					     bool wr_or_deserves_wr,
-+					     bool interactive,
-+					     bool in_burst,
-+					     bool soft_rt)
-+{
-+	if (old_wr_coeff == 1 && wr_or_deserves_wr) {
-+		/* start a weight-raising period */
-+		if (interactive) {
-+			bfqq->wr_coeff = bfqd->bfq_wr_coeff;
-+			bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
-+		} else {
-+			bfqq->wr_start_at_switch_to_srt = jiffies;
-+			bfqq->wr_coeff = bfqd->bfq_wr_coeff *
-+				BFQ_SOFTRT_WEIGHT_FACTOR;
-+			bfqq->wr_cur_max_time =
-+				bfqd->bfq_wr_rt_max_time;
-+		}
-+		/*
-+		 * If needed, further reduce budget to make sure it is
-+		 * close to bfqq's backlog, so as to reduce the
-+		 * scheduling-error component due to a too large
-+		 * budget. Do not care about throughput consequences,
-+		 * but only about latency. Finally, do not assign a
-+		 * too small budget either, to avoid increasing
-+		 * latency by causing too frequent expirations.
-+		 */
-+		bfqq->entity.budget = min_t(unsigned long,
-+					    bfqq->entity.budget,
-+					    2 * bfq_min_budget(bfqd));
-+
-+		bfq_log_bfqq(bfqd, bfqq,
-+			     "wrais starting at %lu, rais_max_time %u",
-+			     jiffies,
-+			     jiffies_to_msecs(bfqq->wr_cur_max_time));
-+	} else if (old_wr_coeff > 1) {
-+		if (interactive) { /* update wr coeff and duration */
-+			bfqq->wr_coeff = bfqd->bfq_wr_coeff;
-+			bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
-+		} else if (in_burst) {
-+			bfqq->wr_coeff = 1;
-+			bfq_log_bfqq(bfqd, bfqq,
-+				     "wrais ending at %lu, rais_max_time %u",
-+				     jiffies,
-+				     jiffies_to_msecs(bfqq->
-+						      wr_cur_max_time));
-+		} else if (soft_rt) {
-+			/*
-+			 * The application is now or still meeting the
-+			 * requirements for being deemed soft rt.  We
-+			 * can then correctly and safely (re)charge
-+			 * the weight-raising duration for the
-+			 * application with the weight-raising
-+			 * duration for soft rt applications.
-+			 *
-+			 * In particular, doing this recharge now, i.e.,
-+			 * before the weight-raising period for the
-+			 * application finishes, reduces the probability
-+			 * of the following negative scenario:
-+			 * 1) the weight of a soft rt application is
-+			 *    raised at startup (as for any newly
-+			 *    created application),
-+			 * 2) since the application is not interactive,
-+			 *    at a certain time weight-raising is
-+			 *    stopped for the application,
-+			 * 3) at that time the application happens to
-+			 *    still have pending requests, and hence
-+			 *    is destined to not have a chance to be
-+			 *    deemed soft rt before these requests are
-+			 *    completed (see the comments to the
-+			 *    function bfq_bfqq_softrt_next_start()
-+			 *    for details on soft rt detection),
-+			 * 4) these pending requests experience a high
-+			 *    latency because the application is not
-+			 *    weight-raised while they are pending.
-+			 */
-+			if (bfqq->wr_cur_max_time !=
-+				bfqd->bfq_wr_rt_max_time) {
-+				bfqq->wr_start_at_switch_to_srt =
-+					bfqq->last_wr_start_finish;
-+                BUG_ON(time_is_after_jiffies(bfqq->last_wr_start_finish));
-+
-+				bfqq->wr_cur_max_time =
-+					bfqd->bfq_wr_rt_max_time;
-+				bfqq->wr_coeff = bfqd->bfq_wr_coeff *
-+					BFQ_SOFTRT_WEIGHT_FACTOR;
-+				bfq_log_bfqq(bfqd, bfqq,
-+					     "switching to soft_rt wr");
-+			} else
-+				bfq_log_bfqq(bfqd, bfqq,
-+					"moving forward soft_rt wr duration");
-+			bfqq->last_wr_start_finish = jiffies;
-+		}
-+	}
-+}
-+
-+static bool bfq_bfqq_idle_for_long_time(struct bfq_data *bfqd,
-+					struct bfq_queue *bfqq)
-+{
-+	return bfqq->dispatched == 0 &&
-+		time_is_before_jiffies(
-+			bfqq->budget_timeout +
-+			bfqd->bfq_wr_min_idle_time);
-+}
-+
-+static void bfq_bfqq_handle_idle_busy_switch(struct bfq_data *bfqd,
-+					     struct bfq_queue *bfqq,
-+					     int old_wr_coeff,
-+					     struct request *rq,
-+					     bool *interactive)
-+{
-+	bool soft_rt, in_burst,	wr_or_deserves_wr,
-+		bfqq_wants_to_preempt,
-+		idle_for_long_time = bfq_bfqq_idle_for_long_time(bfqd, bfqq),
-+		/*
-+		 * See the comments on
-+		 * bfq_bfqq_update_budg_for_activation for
-+		 * details on the usage of the next variable.
-+		 */
-+		arrived_in_time =  ktime_get_ns() <=
-+			RQ_BIC(rq)->ttime.last_end_request +
-+			bfqd->bfq_slice_idle * 3;
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+		     "bfq_add_request non-busy: "
-+		     "jiffies %lu, in_time %d, idle_long %d busyw %d "
-+		     "wr_coeff %u",
-+		     jiffies, arrived_in_time,
-+		     idle_for_long_time,
-+		     bfq_bfqq_non_blocking_wait_rq(bfqq),
-+		     old_wr_coeff);
-+
-+	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
-+
-+	BUG_ON(bfqq == bfqd->in_service_queue);
-+	bfqg_stats_update_io_add(bfqq_group(RQ_BFQQ(rq)), bfqq, rq->cmd_flags);
-+
-+	/*
-+	 * bfqq deserves to be weight-raised if:
-+	 * - it is sync,
-+	 * - it does not belong to a large burst,
-+	 * - it has been idle for enough time or is soft real-time,
-+	 * - is linked to a bfq_io_cq (it is not shared in any sense)
-+	 */
-+	in_burst = bfq_bfqq_in_large_burst(bfqq);
-+	soft_rt = bfqd->bfq_wr_max_softrt_rate > 0 &&
-+		!in_burst &&
-+		time_is_before_jiffies(bfqq->soft_rt_next_start);
-+	*interactive =
-+		!in_burst &&
-+		idle_for_long_time;
-+	wr_or_deserves_wr = bfqd->low_latency &&
-+		(bfqq->wr_coeff > 1 ||
-+		 (bfq_bfqq_sync(bfqq) &&
-+		  bfqq->bic && (*interactive || soft_rt)));
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+		     "bfq_add_request: "
-+		     "in_burst %d, "
-+		     "soft_rt %d (next %lu), inter %d, bic %p",
-+		     bfq_bfqq_in_large_burst(bfqq), soft_rt,
-+		     bfqq->soft_rt_next_start,
-+		     *interactive,
-+		     bfqq->bic);
-+
-+	/*
-+	 * Using the last flag, update budget and check whether bfqq
-+	 * may want to preempt the in-service queue.
-+	 */
-+	bfqq_wants_to_preempt =
-+		bfq_bfqq_update_budg_for_activation(bfqd, bfqq,
-+						    arrived_in_time,
-+						    wr_or_deserves_wr);
-+
-+	/*
-+	 * If bfqq happened to be activated in a burst, but has been
-+	 * idle for much more than an interactive queue, then we
-+	 * assume that, in the overall I/O initiated in the burst, the
-+	 * I/O associated with bfqq is finished. So bfqq does not need
-+	 * to be treated as a queue belonging to a burst
-+	 * anymore. Accordingly, we reset bfqq's in_large_burst flag
-+	 * if set, and remove bfqq from the burst list if it's
-+	 * there. We do not decrement burst_size, because the fact
-+	 * that bfqq does not need to belong to the burst list any
-+	 * more does not invalidate the fact that bfqq was created in
-+	 * a burst.
-+	 */
-+	if (likely(!bfq_bfqq_just_created(bfqq)) &&
-+	    idle_for_long_time &&
-+	    time_is_before_jiffies(
-+		    bfqq->budget_timeout +
-+		    msecs_to_jiffies(10000))) {
-+		hlist_del_init(&bfqq->burst_list_node);
-+		bfq_clear_bfqq_in_large_burst(bfqq);
-+	}
-+
-+	bfq_clear_bfqq_just_created(bfqq);
-+
-+	if (!bfq_bfqq_IO_bound(bfqq)) {
-+		if (arrived_in_time) {
-+			bfqq->requests_within_timer++;
-+			if (bfqq->requests_within_timer >=
-+			    bfqd->bfq_requests_within_timer)
-+				bfq_mark_bfqq_IO_bound(bfqq);
-+		} else
-+			bfqq->requests_within_timer = 0;
-+		bfq_log_bfqq(bfqd, bfqq, "requests in time %d",
-+			     bfqq->requests_within_timer);
-+	}
-+
-+	if (bfqd->low_latency) {
-+		if (unlikely(time_is_after_jiffies(bfqq->split_time)))
-+			/* wraparound */
-+			bfqq->split_time =
-+				jiffies - bfqd->bfq_wr_min_idle_time - 1;
-+
-+		if (time_is_before_jiffies(bfqq->split_time +
-+					   bfqd->bfq_wr_min_idle_time)) {
-+			bfq_update_bfqq_wr_on_rq_arrival(bfqd, bfqq,
-+							 old_wr_coeff,
-+							 wr_or_deserves_wr,
-+							 *interactive,
-+							 in_burst,
-+							 soft_rt);
-+
-+			if (old_wr_coeff != bfqq->wr_coeff)
-+				bfqq->entity.prio_changed = 1;
-+		}
-+	}
-+
-+	bfqq->last_idle_bklogged = jiffies;
-+	bfqq->service_from_backlogged = 0;
-+	bfq_clear_bfqq_softrt_update(bfqq);
-+
-+	bfq_add_bfqq_busy(bfqd, bfqq);
-+
-+	/*
-+	 * Expire in-service queue only if preemption may be needed
-+	 * for guarantees. In this respect, the function
-+	 * next_queue_may_preempt just checks a simple, necessary
-+	 * condition, and not a sufficient condition based on
-+	 * timestamps. In fact, for the latter condition to be
-+	 * evaluated, timestamps would need first to be updated, and
-+	 * this operation is quite costly (see the comments on the
-+	 * function bfq_bfqq_update_budg_for_activation).
-+	 */
-+	if (bfqd->in_service_queue && bfqq_wants_to_preempt &&
-+	    bfqd->in_service_queue->wr_coeff < bfqq->wr_coeff &&
-+	    next_queue_may_preempt(bfqd)) {
-+		struct bfq_queue *in_serv =
-+			bfqd->in_service_queue;
-+		BUG_ON(in_serv == bfqq);
-+
-+		bfq_bfqq_expire(bfqd, bfqd->in_service_queue,
-+				false, BFQ_BFQQ_PREEMPTED);
-+	}
-+}
-+
-+static void bfq_add_request(struct request *rq)
-+{
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq);
-+	struct bfq_data *bfqd = bfqq->bfqd;
-+	struct request *next_rq, *prev;
-+	unsigned int old_wr_coeff = bfqq->wr_coeff;
-+	bool interactive = false;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "add_request: size %u %s",
-+		     blk_rq_sectors(rq), rq_is_sync(rq) ? "S" : "A");
-+
-+	if (bfqq->wr_coeff > 1) /* queue is being weight-raised */
-+		bfq_log_bfqq(bfqd, bfqq,
-+			"raising period dur %u/%u msec, old coeff %u, w %d(%d)",
-+			jiffies_to_msecs(jiffies - bfqq->last_wr_start_finish),
-+			jiffies_to_msecs(bfqq->wr_cur_max_time),
-+			bfqq->wr_coeff,
-+			bfqq->entity.weight, bfqq->entity.orig_weight);
-+
-+	bfqq->queued[rq_is_sync(rq)]++;
-+	bfqd->queued++;
-+
-+	elv_rb_add(&bfqq->sort_list, rq);
-+
-+	/*
-+	 * Check if this request is a better next-to-serve candidate.
-+	 */
-+	prev = bfqq->next_rq;
-+	next_rq = bfq_choose_req(bfqd, bfqq->next_rq, rq, bfqd->last_position);
-+	BUG_ON(!next_rq);
-+	bfqq->next_rq = next_rq;
-+
-+	/*
-+	 * Adjust priority tree position, if next_rq changes.
-+	 */
-+	if (prev != bfqq->next_rq)
-+		bfq_pos_tree_add_move(bfqd, bfqq);
-+
-+	if (!bfq_bfqq_busy(bfqq)) /* switching to busy ... */
-+		bfq_bfqq_handle_idle_busy_switch(bfqd, bfqq, old_wr_coeff,
-+						 rq, &interactive);
-+	else {
-+		if (bfqd->low_latency && old_wr_coeff == 1 && !rq_is_sync(rq) &&
-+		    time_is_before_jiffies(
-+				bfqq->last_wr_start_finish +
-+				bfqd->bfq_wr_min_inter_arr_async)) {
-+			bfqq->wr_coeff = bfqd->bfq_wr_coeff;
-+			bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
-+
-+			bfqd->wr_busy_queues++;
-+			BUG_ON(bfqd->wr_busy_queues > bfqd->busy_queues);
-+			bfqq->entity.prio_changed = 1;
-+			bfq_log_bfqq(bfqd, bfqq,
-+				     "non-idle wrais starting, "
-+				     "wr_max_time %u wr_busy %d",
-+				     jiffies_to_msecs(bfqq->wr_cur_max_time),
-+				     bfqd->wr_busy_queues);
-+		}
-+		if (prev != bfqq->next_rq)
-+			bfq_updated_next_req(bfqd, bfqq);
-+	}
-+
-+	/*
-+	 * Assign jiffies to last_wr_start_finish in the following
-+	 * cases:
-+	 *
-+	 * . if bfqq is not going to be weight-raised, because, for
-+	 *   non weight-raised queues, last_wr_start_finish stores the
-+	 *   arrival time of the last request; as of now, this piece
-+	 *   of information is used only for deciding whether to
-+	 *   weight-raise async queues
-+	 *
-+	 * . if bfqq is not weight-raised, because, if bfqq is now
-+	 *   switching to weight-raised, then last_wr_start_finish
-+	 *   stores the time when weight-raising starts
-+	 *
-+	 * . if bfqq is interactive, because, regardless of whether
-+	 *   bfqq is currently weight-raised, the weight-raising
-+	 *   period must start or restart (this case is considered
-+	 *   separately because it is not detected by the above
-+	 *   conditions, if bfqq is already weight-raised)
-+	 *
-+	 * last_wr_start_finish has to be updated also if bfqq is soft
-+	 * real-time, because the weight-raising period is constantly
-+	 * restarted on idle-to-busy transitions for these queues, but
-+	 * this is already done in bfq_bfqq_handle_idle_busy_switch if
-+	 * needed.
-+	 */
-+	if (bfqd->low_latency &&
-+		(old_wr_coeff == 1 || bfqq->wr_coeff == 1 || interactive))
-+		bfqq->last_wr_start_finish = jiffies;
-+}
-+
-+static struct request *bfq_find_rq_fmerge(struct bfq_data *bfqd,
-+					  struct bio *bio)
-+{
-+	struct task_struct *tsk = current;
-+	struct bfq_io_cq *bic;
-+	struct bfq_queue *bfqq;
-+
-+	bic = bfq_bic_lookup(bfqd, tsk->io_context);
-+	if (!bic)
-+		return NULL;
-+
-+	bfqq = bic_to_bfqq(bic, op_is_sync(bio->bi_opf));
-+	if (bfqq)
-+		return elv_rb_find(&bfqq->sort_list, bio_end_sector(bio));
-+
-+	return NULL;
-+}
-+
-+static sector_t get_sdist(sector_t last_pos, struct request *rq)
-+{
-+	sector_t sdist = 0;
-+
-+	if (last_pos) {
-+		if (last_pos < blk_rq_pos(rq))
-+			sdist = blk_rq_pos(rq) - last_pos;
-+		else
-+			sdist = last_pos - blk_rq_pos(rq);
-+	}
-+
-+	return sdist;
-+}
-+
-+static void bfq_activate_request(struct request_queue *q, struct request *rq)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	bfqd->rq_in_driver++;
-+}
-+
-+static void bfq_deactivate_request(struct request_queue *q, struct request *rq)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+
-+	BUG_ON(bfqd->rq_in_driver == 0);
-+	bfqd->rq_in_driver--;
-+}
-+
-+static void bfq_remove_request(struct request *rq)
-+{
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq);
-+	struct bfq_data *bfqd = bfqq->bfqd;
-+	const int sync = rq_is_sync(rq);
-+
-+	BUG_ON(bfqq->entity.service > bfqq->entity.budget &&
-+	       bfqq == bfqd->in_service_queue);
-+
-+	if (bfqq->next_rq == rq) {
-+		bfqq->next_rq = bfq_find_next_rq(bfqd, bfqq, rq);
-+		bfq_updated_next_req(bfqd, bfqq);
-+	}
-+
-+	if (rq->queuelist.prev != &rq->queuelist)
-+		list_del_init(&rq->queuelist);
-+	BUG_ON(bfqq->queued[sync] == 0);
-+	bfqq->queued[sync]--;
-+	bfqd->queued--;
-+	elv_rb_del(&bfqq->sort_list, rq);
-+
-+	if (RB_EMPTY_ROOT(&bfqq->sort_list)) {
-+		bfqq->next_rq = NULL;
-+
-+		BUG_ON(bfqq->entity.budget < 0);
-+
-+		if (bfq_bfqq_busy(bfqq) && bfqq != bfqd->in_service_queue) {
-+			BUG_ON(bfqq->ref < 2); /* referred by rq and on tree */
-+			bfq_del_bfqq_busy(bfqd, bfqq, false);
-+			/*
-+			 * bfqq emptied. In normal operation, when
-+			 * bfqq is empty, bfqq->entity.service and
-+			 * bfqq->entity.budget must contain,
-+			 * respectively, the service received and the
-+			 * budget used last time bfqq emptied. These
-+			 * facts do not hold in this case, as at least
-+			 * this last removal occurred while bfqq is
-+			 * not in service. To avoid inconsistencies,
-+			 * reset both bfqq->entity.service and
-+			 * bfqq->entity.budget, if bfqq has still a
-+			 * process that may issue I/O requests to it.
-+			 */
-+			bfqq->entity.budget = bfqq->entity.service = 0;
-+		}
-+
-+		/*
-+		 * Remove queue from request-position tree as it is empty.
-+		 */
-+		if (bfqq->pos_root) {
-+			rb_erase(&bfqq->pos_node, bfqq->pos_root);
-+			bfqq->pos_root = NULL;
-+		}
-+	}
-+
-+	if (rq->cmd_flags & REQ_META) {
-+		BUG_ON(bfqq->meta_pending == 0);
-+		bfqq->meta_pending--;
-+	}
-+	bfqg_stats_update_io_remove(bfqq_group(bfqq), rq->cmd_flags);
-+}
-+
-+static enum elv_merge bfq_merge(struct request_queue *q, struct request **req,
-+				struct bio *bio)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	struct request *__rq;
-+
-+	__rq = bfq_find_rq_fmerge(bfqd, bio);
-+	if (__rq && elv_bio_merge_ok(__rq, bio)) {
-+		*req = __rq;
-+		return ELEVATOR_FRONT_MERGE;
-+	}
-+
-+	return ELEVATOR_NO_MERGE;
-+}
-+
-+static void bfq_merged_request(struct request_queue *q, struct request *req,
-+			       enum elv_merge type)
-+{
-+	if (type == ELEVATOR_FRONT_MERGE &&
-+	    rb_prev(&req->rb_node) &&
-+	    blk_rq_pos(req) <
-+	    blk_rq_pos(container_of(rb_prev(&req->rb_node),
-+				    struct request, rb_node))) {
-+		struct bfq_queue *bfqq = RQ_BFQQ(req);
-+		struct bfq_data *bfqd = bfqq->bfqd;
-+		struct request *prev, *next_rq;
-+
-+		/* Reposition request in its sort_list */
-+		elv_rb_del(&bfqq->sort_list, req);
-+		elv_rb_add(&bfqq->sort_list, req);
-+		/* Choose next request to be served for bfqq */
-+		prev = bfqq->next_rq;
-+		next_rq = bfq_choose_req(bfqd, bfqq->next_rq, req,
-+					 bfqd->last_position);
-+		BUG_ON(!next_rq);
-+		bfqq->next_rq = next_rq;
-+		/*
-+		 * If next_rq changes, update both the queue's budget to
-+		 * fit the new request and the queue's position in its
-+		 * rq_pos_tree.
-+		 */
-+		if (prev != bfqq->next_rq) {
-+			bfq_updated_next_req(bfqd, bfqq);
-+			bfq_pos_tree_add_move(bfqd, bfqq);
-+		}
-+	}
-+}
-+
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+static void bfq_bio_merged(struct request_queue *q, struct request *req,
-+			   struct bio *bio)
-+{
-+	bfqg_stats_update_io_merged(bfqq_group(RQ_BFQQ(req)), bio->bi_opf);
-+}
-+#endif
-+
-+static void bfq_merged_requests(struct request_queue *q, struct request *rq,
-+				struct request *next)
-+{
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq), *next_bfqq = RQ_BFQQ(next);
-+
-+	/*
-+	 * If next and rq belong to the same bfq_queue and next is older
-+	 * than rq, then reposition rq in the fifo (by substituting next
-+	 * with rq). Otherwise, if next and rq belong to different
-+	 * bfq_queues, never reposition rq: in fact, we would have to
-+	 * reposition it with respect to next's position in its own fifo,
-+	 * which would most certainly be too expensive with respect to
-+	 * the benefits.
-+	 */
-+	if (bfqq == next_bfqq &&
-+	    !list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
-+	    next->fifo_time < rq->fifo_time) {
-+		list_del_init(&rq->queuelist);
-+		list_replace_init(&next->queuelist, &rq->queuelist);
-+		rq->fifo_time = next->fifo_time;
-+	}
-+
-+	if (bfqq->next_rq == next)
-+		bfqq->next_rq = rq;
-+
-+	bfq_remove_request(next);
-+	bfqg_stats_update_io_merged(bfqq_group(bfqq), next->cmd_flags);
-+}
-+
-+/* Must be called with bfqq != NULL */
-+static void bfq_bfqq_end_wr(struct bfq_queue *bfqq)
-+{
-+	BUG_ON(!bfqq);
-+
-+	if (bfq_bfqq_busy(bfqq)) {
-+		bfqq->bfqd->wr_busy_queues--;
-+		BUG_ON(bfqq->bfqd->wr_busy_queues < 0);
-+	}
-+	bfqq->wr_coeff = 1;
-+	bfqq->wr_cur_max_time = 0;
-+	bfqq->last_wr_start_finish = jiffies;
-+	/*
-+	 * Trigger a weight change on the next invocation of
-+	 * __bfq_entity_update_weight_prio.
-+	 */
-+	bfqq->entity.prio_changed = 1;
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		     "end_wr: wrais ending at %lu, rais_max_time %u",
-+		     bfqq->last_wr_start_finish,
-+		     jiffies_to_msecs(bfqq->wr_cur_max_time));
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "end_wr: wr_busy %d",
-+		     bfqq->bfqd->wr_busy_queues);
-+}
-+
-+static void bfq_end_wr_async_queues(struct bfq_data *bfqd,
-+				    struct bfq_group *bfqg)
-+{
-+	int i, j;
-+
-+	for (i = 0; i < 2; i++)
-+		for (j = 0; j < IOPRIO_BE_NR; j++)
-+			if (bfqg->async_bfqq[i][j])
-+				bfq_bfqq_end_wr(bfqg->async_bfqq[i][j]);
-+	if (bfqg->async_idle_bfqq)
-+		bfq_bfqq_end_wr(bfqg->async_idle_bfqq);
-+}
-+
-+static void bfq_end_wr(struct bfq_data *bfqd)
-+{
-+	struct bfq_queue *bfqq;
-+
-+	spin_lock_irq(bfqd->queue->queue_lock);
-+
-+	list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list)
-+		bfq_bfqq_end_wr(bfqq);
-+	list_for_each_entry(bfqq, &bfqd->idle_list, bfqq_list)
-+		bfq_bfqq_end_wr(bfqq);
-+	bfq_end_wr_async(bfqd);
-+
-+	spin_unlock_irq(bfqd->queue->queue_lock);
-+}
-+
-+static sector_t bfq_io_struct_pos(void *io_struct, bool request)
-+{
-+	if (request)
-+		return blk_rq_pos(io_struct);
-+	else
-+		return ((struct bio *)io_struct)->bi_iter.bi_sector;
-+}
-+
-+static int bfq_rq_close_to_sector(void *io_struct, bool request,
-+				  sector_t sector)
-+{
-+	return abs(bfq_io_struct_pos(io_struct, request) - sector) <=
-+	       BFQQ_CLOSE_THR;
-+}
-+
-+static struct bfq_queue *bfqq_find_close(struct bfq_data *bfqd,
-+					 struct bfq_queue *bfqq,
-+					 sector_t sector)
-+{
-+	struct rb_root *root = &bfq_bfqq_to_bfqg(bfqq)->rq_pos_tree;
-+	struct rb_node *parent, *node;
-+	struct bfq_queue *__bfqq;
-+
-+	if (RB_EMPTY_ROOT(root))
-+		return NULL;
-+
-+	/*
-+	 * First, if we find a request starting at the end of the last
-+	 * request, choose it.
-+	 */
-+	__bfqq = bfq_rq_pos_tree_lookup(bfqd, root, sector, &parent, NULL);
-+	if (__bfqq)
-+		return __bfqq;
-+
-+	/*
-+	 * If the exact sector wasn't found, the parent of the NULL leaf
-+	 * will contain the closest sector (rq_pos_tree sorted by
-+	 * next_request position).
-+	 */
-+	__bfqq = rb_entry(parent, struct bfq_queue, pos_node);
-+	if (bfq_rq_close_to_sector(__bfqq->next_rq, true, sector))
-+		return __bfqq;
-+
-+	if (blk_rq_pos(__bfqq->next_rq) < sector)
-+		node = rb_next(&__bfqq->pos_node);
-+	else
-+		node = rb_prev(&__bfqq->pos_node);
-+	if (!node)
-+		return NULL;
-+
-+	__bfqq = rb_entry(node, struct bfq_queue, pos_node);
-+	if (bfq_rq_close_to_sector(__bfqq->next_rq, true, sector))
-+		return __bfqq;
-+
-+	return NULL;
-+}
-+
-+static struct bfq_queue *bfq_find_close_cooperator(struct bfq_data *bfqd,
-+						   struct bfq_queue *cur_bfqq,
-+						   sector_t sector)
-+{
-+	struct bfq_queue *bfqq;
-+
-+	/*
-+	 * We shall notice if some of the queues are cooperating,
-+	 * e.g., working closely on the same area of the device. In
-+	 * that case, we can group them together and: 1) don't waste
-+	 * time idling, and 2) serve the union of their requests in
-+	 * the best possible order for throughput.
-+	 */
-+	bfqq = bfqq_find_close(bfqd, cur_bfqq, sector);
-+	if (!bfqq || bfqq == cur_bfqq)
-+		return NULL;
-+
-+	return bfqq;
-+}
-+
-+static struct bfq_queue *
-+bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq)
-+{
-+	int process_refs, new_process_refs;
-+	struct bfq_queue *__bfqq;
-+
-+	/*
-+	 * If there are no process references on the new_bfqq, then it is
-+	 * unsafe to follow the ->new_bfqq chain as other bfqq's in the chain
-+	 * may have dropped their last reference (not just their last process
-+	 * reference).
-+	 */
-+	if (!bfqq_process_refs(new_bfqq))
-+		return NULL;
-+
-+	/* Avoid a circular list and skip interim queue merges. */
-+	while ((__bfqq = new_bfqq->new_bfqq)) {
-+		if (__bfqq == bfqq)
-+			return NULL;
-+		new_bfqq = __bfqq;
-+	}
-+
-+	process_refs = bfqq_process_refs(bfqq);
-+	new_process_refs = bfqq_process_refs(new_bfqq);
-+	/*
-+	 * If the process for the bfqq has gone away, there is no
-+	 * sense in merging the queues.
-+	 */
-+	if (process_refs == 0 || new_process_refs == 0)
-+		return NULL;
-+
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "scheduling merge with queue %d",
-+		new_bfqq->pid);
-+
-+	/*
-+	 * Merging is just a redirection: the requests of the process
-+	 * owning one of the two queues are redirected to the other queue.
-+	 * The latter queue, in its turn, is set as shared if this is the
-+	 * first time that the requests of some process are redirected to
-+	 * it.
-+	 *
-+	 * We redirect bfqq to new_bfqq and not the opposite, because we
-+	 * are in the context of the process owning bfqq, hence we have
-+	 * the io_cq of this process. So we can immediately configure this
-+	 * io_cq to redirect the requests of the process to new_bfqq.
-+	 *
-+	 * NOTE, even if new_bfqq coincides with the in-service queue, the
-+	 * io_cq of new_bfqq is not available, because, if the in-service
-+	 * queue is shared, bfqd->in_service_bic may not point to the
-+	 * io_cq of the in-service queue.
-+	 * Redirecting the requests of the process owning bfqq to the
-+	 * currently in-service queue is in any case the best option, as
-+	 * we feed the in-service queue with new requests close to the
-+	 * last request served and, by doing so, hopefully increase the
-+	 * throughput.
-+	 */
-+	bfqq->new_bfqq = new_bfqq;
-+	new_bfqq->ref += process_refs;
-+	return new_bfqq;
-+}
-+
-+static bool bfq_may_be_close_cooperator(struct bfq_queue *bfqq,
-+					struct bfq_queue *new_bfqq)
-+{
-+	if (bfq_class_idle(bfqq) || bfq_class_idle(new_bfqq) ||
-+	    (bfqq->ioprio_class != new_bfqq->ioprio_class))
-+		return false;
-+
-+	/*
-+	 * If either of the queues has already been detected as seeky,
-+	 * then merging it with the other queue is unlikely to lead to
-+	 * sequential I/O.
-+	 */
-+	if (BFQQ_SEEKY(bfqq) || BFQQ_SEEKY(new_bfqq))
-+		return false;
-+
-+	/*
-+	 * Interleaved I/O is known to be done by (some) applications
-+	 * only for reads, so it does not make sense to merge async
-+	 * queues.
-+	 */
-+	if (!bfq_bfqq_sync(bfqq) || !bfq_bfqq_sync(new_bfqq))
-+		return false;
-+
-+	return true;
-+}
-+
-+/*
-+ * If this function returns true, then bfqq cannot be merged. The idea
-+ * is that true cooperation happens very early after processes start
-+ * to do I/O. Usually, late cooperations are just accidental false
-+ * positives. In case bfqq is weight-raised, such false positives
-+ * would evidently degrade latency guarantees for bfqq.
-+ */
-+static bool wr_from_too_long(struct bfq_queue *bfqq)
-+{
-+	return bfqq->wr_coeff > 1 &&
-+		time_is_before_jiffies(bfqq->last_wr_start_finish +
-+				       msecs_to_jiffies(100));
-+}
-+
-+/*
-+ * Attempt to schedule a merge of bfqq with the currently in-service
-+ * queue or with a close queue among the scheduled queues.  Return
-+ * NULL if no merge was scheduled, a pointer to the shared bfq_queue
-+ * structure otherwise.
-+ *
-+ * The OOM queue is not allowed to participate to cooperation: in fact, since
-+ * the requests temporarily redirected to the OOM queue could be redirected
-+ * again to dedicated queues at any time, the state needed to correctly
-+ * handle merging with the OOM queue would be quite complex and expensive
-+ * to maintain. Besides, in such a critical condition as an out of memory,
-+ * the benefits of queue merging may be little relevant, or even negligible.
-+ *
-+ * Weight-raised queues can be merged only if their weight-raising
-+ * period has just started. In fact cooperating processes are usually
-+ * started together. Thus, with this filter we avoid false positives
-+ * that would jeopardize low-latency guarantees.
-+ *
-+ * WARNING: queue merging may impair fairness among non-weight raised
-+ * queues, for at least two reasons: 1) the original weight of a
-+ * merged queue may change during the merged state, 2) even being the
-+ * weight the same, a merged queue may be bloated with many more
-+ * requests than the ones produced by its originally-associated
-+ * process.
-+ */
-+static struct bfq_queue *
-+bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+		     void *io_struct, bool request)
-+{
-+	struct bfq_queue *in_service_bfqq, *new_bfqq;
-+
-+	if (bfqq->new_bfqq)
-+		return bfqq->new_bfqq;
-+
-+	if (io_struct && wr_from_too_long(bfqq) &&
-+	    likely(bfqq != &bfqd->oom_bfqq))
-+		bfq_log_bfqq(bfqd, bfqq,
-+			     "would have looked for coop, but bfq%d wr",
-+			bfqq->pid);
-+
-+	if (!io_struct ||
-+	    wr_from_too_long(bfqq) ||
-+	    unlikely(bfqq == &bfqd->oom_bfqq))
-+		return NULL;
-+
-+	/* If there is only one backlogged queue, don't search. */
-+	if (bfqd->busy_queues == 1)
-+		return NULL;
-+
-+	in_service_bfqq = bfqd->in_service_queue;
-+
-+	if (in_service_bfqq && in_service_bfqq != bfqq &&
-+	    bfqd->in_service_bic && wr_from_too_long(in_service_bfqq)
-+	    && likely(in_service_bfqq == &bfqd->oom_bfqq))
-+		bfq_log_bfqq(bfqd, bfqq,
-+		"would have tried merge with in-service-queue, but wr");
-+
-+	if (!in_service_bfqq || in_service_bfqq == bfqq ||
-+	    !bfqd->in_service_bic || wr_from_too_long(in_service_bfqq) ||
-+	    unlikely(in_service_bfqq == &bfqd->oom_bfqq))
-+		goto check_scheduled;
-+
-+	if (bfq_rq_close_to_sector(io_struct, request, bfqd->last_position) &&
-+	    bfqq->entity.parent == in_service_bfqq->entity.parent &&
-+	    bfq_may_be_close_cooperator(bfqq, in_service_bfqq)) {
-+		new_bfqq = bfq_setup_merge(bfqq, in_service_bfqq);
-+		if (new_bfqq)
-+			return new_bfqq;
-+	}
-+	/*
-+	 * Check whether there is a cooperator among currently scheduled
-+	 * queues. The only thing we need is that the bio/request is not
-+	 * NULL, as we need it to establish whether a cooperator exists.
-+	 */
-+check_scheduled:
-+	new_bfqq = bfq_find_close_cooperator(bfqd, bfqq,
-+			bfq_io_struct_pos(io_struct, request));
-+
-+	BUG_ON(new_bfqq && bfqq->entity.parent != new_bfqq->entity.parent);
-+
-+	if (new_bfqq && wr_from_too_long(new_bfqq) &&
-+	    likely(new_bfqq != &bfqd->oom_bfqq) &&
-+	    bfq_may_be_close_cooperator(bfqq, new_bfqq))
-+		bfq_log_bfqq(bfqd, bfqq,
-+			     "would have merged with bfq%d, but wr",
-+			     new_bfqq->pid);
-+
-+	if (new_bfqq && !wr_from_too_long(new_bfqq) &&
-+	    likely(new_bfqq != &bfqd->oom_bfqq) &&
-+	    bfq_may_be_close_cooperator(bfqq, new_bfqq))
-+		return bfq_setup_merge(bfqq, new_bfqq);
-+
-+	return NULL;
-+}
-+
-+static void bfq_bfqq_save_state(struct bfq_queue *bfqq)
-+{
-+	struct bfq_io_cq *bic = bfqq->bic;
-+
-+	/*
-+	 * If !bfqq->bic, the queue is already shared or its requests
-+	 * have already been redirected to a shared queue; both idle window
-+	 * and weight raising state have already been saved. Do nothing.
-+	 */
-+	if (!bic)
-+		return;
-+
-+	bic->saved_idle_window = bfq_bfqq_idle_window(bfqq);
-+	bic->saved_IO_bound = bfq_bfqq_IO_bound(bfqq);
-+	bic->saved_in_large_burst = bfq_bfqq_in_large_burst(bfqq);
-+	bic->was_in_burst_list = !hlist_unhashed(&bfqq->burst_list_node);
-+	bic->saved_wr_coeff = bfqq->wr_coeff;
-+	bic->saved_wr_start_at_switch_to_srt = bfqq->wr_start_at_switch_to_srt;
-+	bic->saved_last_wr_start_finish = bfqq->last_wr_start_finish;
-+	bic->saved_wr_cur_max_time = bfqq->wr_cur_max_time;
-+	BUG_ON(time_is_after_jiffies(bfqq->last_wr_start_finish));
-+}
-+
-+static void bfq_get_bic_reference(struct bfq_queue *bfqq)
-+{
-+	/*
-+	 * If bfqq->bic has a non-NULL value, the bic to which it belongs
-+	 * is about to begin using a shared bfq_queue.
-+	 */
-+	if (bfqq->bic)
-+		atomic_long_inc(&bfqq->bic->icq.ioc->refcount);
-+}
-+
-+static void
-+bfq_merge_bfqqs(struct bfq_data *bfqd, struct bfq_io_cq *bic,
-+		struct bfq_queue *bfqq, struct bfq_queue *new_bfqq)
-+{
-+	bfq_log_bfqq(bfqd, bfqq, "merging with queue %lu",
-+		     (unsigned long) new_bfqq->pid);
-+	/* Save weight raising and idle window of the merged queues */
-+	bfq_bfqq_save_state(bfqq);
-+	bfq_bfqq_save_state(new_bfqq);
-+	if (bfq_bfqq_IO_bound(bfqq))
-+		bfq_mark_bfqq_IO_bound(new_bfqq);
-+	bfq_clear_bfqq_IO_bound(bfqq);
-+
-+	/*
-+	 * If bfqq is weight-raised, then let new_bfqq inherit
-+	 * weight-raising. To reduce false positives, neglect the case
-+	 * where bfqq has just been created, but has not yet made it
-+	 * to be weight-raised (which may happen because EQM may merge
-+	 * bfqq even before bfq_add_request is executed for the first
-+	 * time for bfqq). Handling this case would however be very
-+	 * easy, thanks to the flag just_created.
-+	 */
-+	if (new_bfqq->wr_coeff == 1 && bfqq->wr_coeff > 1) {
-+		new_bfqq->wr_coeff = bfqq->wr_coeff;
-+		new_bfqq->wr_cur_max_time = bfqq->wr_cur_max_time;
-+		new_bfqq->last_wr_start_finish = bfqq->last_wr_start_finish;
-+		new_bfqq->wr_start_at_switch_to_srt =
-+			bfqq->wr_start_at_switch_to_srt;
-+		if (bfq_bfqq_busy(new_bfqq)) {
-+			bfqd->wr_busy_queues++;
-+			BUG_ON(bfqd->wr_busy_queues > bfqd->busy_queues);
-+		}
-+
-+		new_bfqq->entity.prio_changed = 1;
-+		bfq_log_bfqq(bfqd, new_bfqq,
-+			     "wr start after merge with %d, rais_max_time %u",
-+			     bfqq->pid,
-+			     jiffies_to_msecs(bfqq->wr_cur_max_time));
-+	}
-+
-+	if (bfqq->wr_coeff > 1) { /* bfqq has given its wr to new_bfqq */
-+		bfqq->wr_coeff = 1;
-+		bfqq->entity.prio_changed = 1;
-+		if (bfq_bfqq_busy(bfqq)) {
-+			bfqd->wr_busy_queues--;
-+			BUG_ON(bfqd->wr_busy_queues < 0);
-+		}
-+
-+	}
-+
-+	bfq_log_bfqq(bfqd, new_bfqq, "merge_bfqqs: wr_busy %d",
-+		     bfqd->wr_busy_queues);
-+
-+	/*
-+	 * Grab a reference to the bic, to prevent it from being destroyed
-+	 * before being possibly touched by a bfq_split_bfqq().
-+	 */
-+	bfq_get_bic_reference(bfqq);
-+	bfq_get_bic_reference(new_bfqq);
-+	/*
-+	 * Merge queues (that is, let bic redirect its requests to new_bfqq)
-+	 */
-+	bic_set_bfqq(bic, new_bfqq, 1);
-+	bfq_mark_bfqq_coop(new_bfqq);
-+	/*
-+	 * new_bfqq now belongs to at least two bics (it is a shared queue):
-+	 * set new_bfqq->bic to NULL. bfqq either:
-+	 * - does not belong to any bic any more, and hence bfqq->bic must
-+	 *   be set to NULL, or
-+	 * - is a queue whose owning bics have already been redirected to a
-+	 *   different queue, hence the queue is destined to not belong to
-+	 *   any bic soon and bfqq->bic is already NULL (therefore the next
-+	 *   assignment causes no harm).
-+	 */
-+	new_bfqq->bic = NULL;
-+	bfqq->bic = NULL;
-+	/* release process reference to bfqq */
-+	bfq_put_queue(bfqq);
-+}
-+
-+static int bfq_allow_bio_merge(struct request_queue *q, struct request *rq,
-+			       struct bio *bio)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	bool is_sync = op_is_sync(bio->bi_opf);
-+	struct bfq_io_cq *bic;
-+	struct bfq_queue *bfqq, *new_bfqq;
-+
-+	/*
-+	 * Disallow merge of a sync bio into an async request.
-+	 */
-+	if (is_sync && !rq_is_sync(rq))
-+		return false;
-+
-+	/*
-+	 * Lookup the bfqq that this bio will be queued with. Allow
-+	 * merge only if rq is queued there.
-+	 * Queue lock is held here.
-+	 */
-+	bic = bfq_bic_lookup(bfqd, current->io_context);
-+	if (!bic)
-+		return false;
-+
-+	bfqq = bic_to_bfqq(bic, is_sync);
-+	/*
-+	 * We take advantage of this function to perform an early merge
-+	 * of the queues of possible cooperating processes.
-+	 */
-+	if (bfqq) {
-+		new_bfqq = bfq_setup_cooperator(bfqd, bfqq, bio, false);
-+		if (new_bfqq) {
-+			bfq_merge_bfqqs(bfqd, bic, bfqq, new_bfqq);
-+			/*
-+			 * If we get here, the bio will be queued in the
-+			 * shared queue, i.e., new_bfqq, so use new_bfqq
-+			 * to decide whether bio and rq can be merged.
-+			 */
-+			bfqq = new_bfqq;
-+		}
-+	}
-+
-+	return bfqq == RQ_BFQQ(rq);
-+}
-+
-+static int bfq_allow_rq_merge(struct request_queue *q, struct request *rq,
-+			      struct request *next)
-+{
-+	return RQ_BFQQ(rq) == RQ_BFQQ(next);
-+}
-+
-+/*
-+ * Set the maximum time for the in-service queue to consume its
-+ * budget. This prevents seeky processes from lowering the throughput.
-+ * In practice, a time-slice service scheme is used with seeky
-+ * processes.
-+ */
-+static void bfq_set_budget_timeout(struct bfq_data *bfqd,
-+				   struct bfq_queue *bfqq)
-+{
-+	unsigned int timeout_coeff;
-+
-+	if (bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time)
-+		timeout_coeff = 1;
-+	else
-+		timeout_coeff = bfqq->entity.weight / bfqq->entity.orig_weight;
-+
-+	bfqd->last_budget_start = ktime_get();
-+
-+	bfqq->budget_timeout = jiffies +
-+		bfqd->bfq_timeout * timeout_coeff;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "set budget_timeout %u",
-+		jiffies_to_msecs(bfqd->bfq_timeout * timeout_coeff));
-+}
-+
-+static void __bfq_set_in_service_queue(struct bfq_data *bfqd,
-+				       struct bfq_queue *bfqq)
-+{
-+	if (bfqq) {
-+		bfqg_stats_update_avg_queue_size(bfqq_group(bfqq));
-+		bfq_mark_bfqq_must_alloc(bfqq);
-+		bfq_clear_bfqq_fifo_expire(bfqq);
-+
-+		bfqd->budgets_assigned = (bfqd->budgets_assigned*7 + 256) / 8;
-+
-+		BUG_ON(bfqq == bfqd->in_service_queue);
-+		BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list));
-+
-+		if (time_is_before_jiffies(bfqq->last_wr_start_finish) &&
-+		    bfqq->wr_coeff > 1 &&
-+		    bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time &&
-+		    time_is_before_jiffies(bfqq->budget_timeout)) {
-+			/*
-+			 * For soft real-time queues, move the start
-+			 * of the weight-raising period forward by the
-+			 * time the queue has not received any
-+			 * service. Otherwise, a relatively long
-+			 * service delay is likely to cause the
-+			 * weight-raising period of the queue to end,
-+			 * because of the short duration of the
-+			 * weight-raising period of a soft real-time
-+			 * queue.  It is worth noting that this move
-+			 * is not so dangerous for the other queues,
-+			 * because soft real-time queues are not
-+			 * greedy.
-+			 *
-+			 * To not add a further variable, we use the
-+			 * overloaded field budget_timeout to
-+			 * determine for how long the queue has not
-+			 * received service, i.e., how much time has
-+			 * elapsed since the queue expired. However,
-+			 * this is a little imprecise, because
-+			 * budget_timeout is set to jiffies if bfqq
-+			 * not only expires, but also remains with no
-+			 * request.
-+			 */
-+			if (time_after(bfqq->budget_timeout,
-+				       bfqq->last_wr_start_finish))
-+				bfqq->last_wr_start_finish +=
-+					jiffies - bfqq->budget_timeout;
-+			else
-+				bfqq->last_wr_start_finish = jiffies;
-+
-+			if (time_is_after_jiffies(bfqq->last_wr_start_finish)) {
-+			       pr_crit(
-+			       "BFQ WARNING:last %lu budget %lu jiffies %lu",
-+			       bfqq->last_wr_start_finish,
-+			       bfqq->budget_timeout,
-+			       jiffies);
-+			       pr_crit("diff %lu", jiffies -
-+				       max_t(unsigned long,
-+					     bfqq->last_wr_start_finish,
-+					     bfqq->budget_timeout));
-+			       bfqq->last_wr_start_finish = jiffies;
-+			}
-+		}
-+
-+		bfq_set_budget_timeout(bfqd, bfqq);
-+		bfq_log_bfqq(bfqd, bfqq,
-+			     "set_in_service_queue, cur-budget = %d",
-+			     bfqq->entity.budget);
-+	} else
-+		bfq_log(bfqd, "set_in_service_queue: NULL");
-+
-+	bfqd->in_service_queue = bfqq;
-+}
-+
-+/*
-+ * Get and set a new queue for service.
-+ */
-+static struct bfq_queue *bfq_set_in_service_queue(struct bfq_data *bfqd)
-+{
-+	struct bfq_queue *bfqq = bfq_get_next_queue(bfqd);
-+
-+	__bfq_set_in_service_queue(bfqd, bfqq);
-+	return bfqq;
-+}
-+
-+static void bfq_arm_slice_timer(struct bfq_data *bfqd)
-+{
-+	struct bfq_queue *bfqq = bfqd->in_service_queue;
-+	struct bfq_io_cq *bic;
-+	u32 sl;
-+
-+	BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list));
-+
-+	/* Processes have exited, don't wait. */
-+	bic = bfqd->in_service_bic;
-+	if (!bic || atomic_read(&bic->icq.ioc->active_ref) == 0)
-+		return;
-+
-+	bfq_mark_bfqq_wait_request(bfqq);
-+
-+	/*
-+	 * We don't want to idle for seeks, but we do want to allow
-+	 * fair distribution of slice time for a process doing back-to-back
-+	 * seeks. So allow a little bit of time for him to submit a new rq.
-+	 *
-+	 * To prevent processes with (partly) seeky workloads from
-+	 * being too ill-treated, grant them a small fraction of the
-+	 * assigned budget before reducing the waiting time to
-+	 * BFQ_MIN_TT. This happened to help reduce latency.
-+	 */
-+	sl = bfqd->bfq_slice_idle;
-+	/*
-+	 * Unless the queue is being weight-raised or the scenario is
-+	 * asymmetric, grant only minimum idle time if the queue
-+	 * is seeky. A long idling is preserved for a weight-raised
-+	 * queue, or, more in general, in an asymemtric scenario,
-+	 * because a long idling is needed for guaranteeing to a queue
-+	 * its reserved share of the throughput (in particular, it is
-+	 * needed if the queue has a higher weight than some other
-+	 * queue).
-+	 */
-+	if (BFQQ_SEEKY(bfqq) && bfqq->wr_coeff == 1 &&
-+	    bfq_symmetric_scenario(bfqd))
-+		sl = min_t(u32, sl, BFQ_MIN_TT);
-+
-+	bfqd->last_idling_start = ktime_get();
-+	hrtimer_start(&bfqd->idle_slice_timer, ns_to_ktime(sl),
-+		      HRTIMER_MODE_REL);
-+	bfqg_stats_set_start_idle_time(bfqq_group(bfqq));
-+	bfq_log(bfqd, "arm idle: %ld/%ld ms",
-+		sl / NSEC_PER_MSEC, bfqd->bfq_slice_idle / NSEC_PER_MSEC);
-+}
-+
-+/*
-+ * In autotuning mode, max_budget is dynamically recomputed as the
-+ * amount of sectors transferred in timeout at the estimated peak
-+ * rate. This enables BFQ to utilize a full timeslice with a full
-+ * budget, even if the in-service queue is served at peak rate. And
-+ * this maximises throughput with sequential workloads.
-+ */
-+static unsigned long bfq_calc_max_budget(struct bfq_data *bfqd)
-+{
-+	return (u64)bfqd->peak_rate * USEC_PER_MSEC *
-+		jiffies_to_msecs(bfqd->bfq_timeout)>>BFQ_RATE_SHIFT;
-+}
-+
-+/*
-+ * Update parameters related to throughput and responsiveness, as a
-+ * function of the estimated peak rate. See comments on
-+ * bfq_calc_max_budget(), and on T_slow and T_fast arrays.
-+ */
-+static void update_thr_responsiveness_params(struct bfq_data *bfqd)
-+{
-+	int dev_type = blk_queue_nonrot(bfqd->queue);
-+
-+	if (bfqd->bfq_user_max_budget == 0) {
-+		bfqd->bfq_max_budget =
-+			bfq_calc_max_budget(bfqd);
-+		BUG_ON(bfqd->bfq_max_budget < 0);
-+		bfq_log(bfqd, "new max_budget = %d",
-+			bfqd->bfq_max_budget);
-+	}
-+
-+	if (bfqd->device_speed == BFQ_BFQD_FAST &&
-+	    bfqd->peak_rate < device_speed_thresh[dev_type]) {
-+		bfqd->device_speed = BFQ_BFQD_SLOW;
-+		bfqd->RT_prod = R_slow[dev_type] *
-+			T_slow[dev_type];
-+	} else if (bfqd->device_speed == BFQ_BFQD_SLOW &&
-+		   bfqd->peak_rate > device_speed_thresh[dev_type]) {
-+		bfqd->device_speed = BFQ_BFQD_FAST;
-+		bfqd->RT_prod = R_fast[dev_type] *
-+			T_fast[dev_type];
-+	}
-+
-+	bfq_log(bfqd,
-+"dev_type %s dev_speed_class = %s (%llu sects/sec), thresh %llu setcs/sec",
-+		dev_type == 0 ? "ROT" : "NONROT",
-+		bfqd->device_speed == BFQ_BFQD_FAST ? "FAST" : "SLOW",
-+		bfqd->device_speed == BFQ_BFQD_FAST ?
-+		(USEC_PER_SEC*(u64)R_fast[dev_type])>>BFQ_RATE_SHIFT :
-+		(USEC_PER_SEC*(u64)R_slow[dev_type])>>BFQ_RATE_SHIFT,
-+		(USEC_PER_SEC*(u64)device_speed_thresh[dev_type])>>
-+		BFQ_RATE_SHIFT);
-+}
-+
-+static void bfq_reset_rate_computation(struct bfq_data *bfqd, struct request *rq)
-+{
-+	if (rq != NULL) { /* new rq dispatch now, reset accordingly */
-+		bfqd->last_dispatch = bfqd->first_dispatch = ktime_get_ns() ;
-+		bfqd->peak_rate_samples = 1;
-+		bfqd->sequential_samples = 0;
-+		bfqd->tot_sectors_dispatched = bfqd->last_rq_max_size =
-+			blk_rq_sectors(rq);
-+	} else /* no new rq dispatched, just reset the number of samples */
-+		bfqd->peak_rate_samples = 0; /* full re-init on next disp. */
-+
-+	bfq_log(bfqd,
-+		"reset_rate_computation at end, sample %u/%u tot_sects %llu",
-+		bfqd->peak_rate_samples, bfqd->sequential_samples,
-+		bfqd->tot_sectors_dispatched);
-+}
-+
-+static void bfq_update_rate_reset(struct bfq_data *bfqd, struct request *rq)
-+{
-+	u32 rate, weight, divisor;
-+
-+	/*
-+	 * For the convergence property to hold (see comments on
-+	 * bfq_update_peak_rate()) and for the assessment to be
-+	 * reliable, a minimum number of samples must be present, and
-+	 * a minimum amount of time must have elapsed. If not so, do
-+	 * not compute new rate. Just reset parameters, to get ready
-+	 * for a new evaluation attempt.
-+	 */
-+	if (bfqd->peak_rate_samples < BFQ_RATE_MIN_SAMPLES ||
-+	    bfqd->delta_from_first < BFQ_RATE_MIN_INTERVAL) {
-+		bfq_log(bfqd,
-+	"update_rate_reset: only resetting, delta_first %lluus samples %d",
-+			bfqd->delta_from_first>>10, bfqd->peak_rate_samples);
-+		goto reset_computation;
-+	}
-+
-+	/*
-+	 * If a new request completion has occurred after last
-+	 * dispatch, then, to approximate the rate at which requests
-+	 * have been served by the device, it is more precise to
-+	 * extend the observation interval to the last completion.
-+	 */
-+	bfqd->delta_from_first =
-+		max_t(u64, bfqd->delta_from_first,
-+		      bfqd->last_completion - bfqd->first_dispatch);
-+
-+	BUG_ON(bfqd->delta_from_first == 0);
-+	/*
-+	 * Rate computed in sects/usec, and not sects/nsec, for
-+	 * precision issues.
-+	 */
-+	rate = div64_ul(bfqd->tot_sectors_dispatched<<BFQ_RATE_SHIFT,
-+			div_u64(bfqd->delta_from_first, NSEC_PER_USEC));
-+
-+	bfq_log(bfqd,
-+"update_rate_reset: tot_sects %llu delta_first %lluus rate %llu sects/s (%d)",
-+		bfqd->tot_sectors_dispatched, bfqd->delta_from_first>>10,
-+		((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT),
-+		rate > 20<<BFQ_RATE_SHIFT);
-+
-+	/*
-+	 * Peak rate not updated if:
-+	 * - the percentage of sequential dispatches is below 3/4 of the
-+	 *   total, and rate is below the current estimated peak rate
-+	 * - rate is unreasonably high (> 20M sectors/sec)
-+	 */
-+	if ((bfqd->sequential_samples < (3 * bfqd->peak_rate_samples)>>2 &&
-+	     rate <= bfqd->peak_rate) ||
-+		rate > 20<<BFQ_RATE_SHIFT) {
-+		bfq_log(bfqd,
-+		"update_rate_reset: goto reset, samples %u/%u rate/peak %llu/%llu",
-+		bfqd->peak_rate_samples, bfqd->sequential_samples,
-+		((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT),
-+		((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT));
-+		goto reset_computation;
-+	} else {
-+		bfq_log(bfqd,
-+		"update_rate_reset: do update, samples %u/%u rate/peak %llu/%llu",
-+		bfqd->peak_rate_samples, bfqd->sequential_samples,
-+		((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT),
-+		((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT));
-+	}
-+
-+	/*
-+	 * We have to update the peak rate, at last! To this purpose,
-+	 * we use a low-pass filter. We compute the smoothing constant
-+	 * of the filter as a function of the 'weight' of the new
-+	 * measured rate.
-+	 *
-+	 * As can be seen in next formulas, we define this weight as a
-+	 * quantity proportional to how sequential the workload is,
-+	 * and to how long the observation time interval is.
-+	 *
-+	 * The weight runs from 0 to 8. The maximum value of the
-+	 * weight, 8, yields the minimum value for the smoothing
-+	 * constant. At this minimum value for the smoothing constant,
-+	 * the measured rate contributes for half of the next value of
-+	 * the estimated peak rate.
-+	 *
-+	 * So, the first step is to compute the weight as a function
-+	 * of how sequential the workload is. Note that the weight
-+	 * cannot reach 9, because bfqd->sequential_samples cannot
-+	 * become equal to bfqd->peak_rate_samples, which, in its
-+	 * turn, holds true because bfqd->sequential_samples is not
-+	 * incremented for the first sample.
-+	 */
-+	weight = (9 * bfqd->sequential_samples) / bfqd->peak_rate_samples;
-+
-+	/*
-+	 * Second step: further refine the weight as a function of the
-+	 * duration of the observation interval.
-+	 */
-+	weight = min_t(u32, 8,
-+		       div_u64(weight * bfqd->delta_from_first,
-+			       BFQ_RATE_REF_INTERVAL));
-+
-+	/*
-+	 * Divisor ranging from 10, for minimum weight, to 2, for
-+	 * maximum weight.
-+	 */
-+	divisor = 10 - weight;
-+	BUG_ON(divisor == 0);
-+
-+	/*
-+	 * Finally, update peak rate:
-+	 *
-+	 * peak_rate = peak_rate * (divisor-1) / divisor  +  rate / divisor
-+	 */
-+	bfqd->peak_rate *= divisor-1;
-+	bfqd->peak_rate /= divisor;
-+	rate /= divisor; /* smoothing constant alpha = 1/divisor */
-+
-+	bfq_log(bfqd,
-+		"update_rate_reset: divisor %d tmp_peak_rate %llu tmp_rate %u",
-+		divisor,
-+		((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT),
-+		(u32)((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT));
-+
-+	BUG_ON(bfqd->peak_rate == 0);
-+	BUG_ON(bfqd->peak_rate > 20<<BFQ_RATE_SHIFT);
-+
-+	bfqd->peak_rate += rate;
-+	update_thr_responsiveness_params(bfqd);
-+	BUG_ON(bfqd->peak_rate > 20<<BFQ_RATE_SHIFT);
-+
-+reset_computation:
-+	bfq_reset_rate_computation(bfqd, rq);
-+}
-+
-+/*
-+ * Update the read/write peak rate (the main quantity used for
-+ * auto-tuning, see update_thr_responsiveness_params()).
-+ *
-+ * It is not trivial to estimate the peak rate (correctly): because of
-+ * the presence of sw and hw queues between the scheduler and the
-+ * device components that finally serve I/O requests, it is hard to
-+ * say exactly when a given dispatched request is served inside the
-+ * device, and for how long. As a consequence, it is hard to know
-+ * precisely at what rate a given set of requests is actually served
-+ * by the device.
-+ *
-+ * On the opposite end, the dispatch time of any request is trivially
-+ * available, and, from this piece of information, the "dispatch rate"
-+ * of requests can be immediately computed. So, the idea in the next
-+ * function is to use what is known, namely request dispatch times
-+ * (plus, when useful, request completion times), to estimate what is
-+ * unknown, namely in-device request service rate.
-+ *
-+ * The main issue is that, because of the above facts, the rate at
-+ * which a certain set of requests is dispatched over a certain time
-+ * interval can vary greatly with respect to the rate at which the
-+ * same requests are then served. But, since the size of any
-+ * intermediate queue is limited, and the service scheme is lossless
-+ * (no request is silently dropped), the following obvious convergence
-+ * property holds: the number of requests dispatched MUST become
-+ * closer and closer to the number of requests completed as the
-+ * observation interval grows. This is the key property used in
-+ * the next function to estimate the peak service rate as a function
-+ * of the observed dispatch rate. The function assumes to be invoked
-+ * on every request dispatch.
-+ */
-+static void bfq_update_peak_rate(struct bfq_data *bfqd, struct request *rq)
-+{
-+	u64 now_ns = ktime_get_ns();
-+
-+	if (bfqd->peak_rate_samples == 0) { /* first dispatch */
-+		bfq_log(bfqd,
-+		"update_peak_rate: goto reset, samples %d",
-+				bfqd->peak_rate_samples) ;
-+		bfq_reset_rate_computation(bfqd, rq);
-+		goto update_last_values; /* will add one sample */
-+	}
-+
-+	/*
-+	 * Device idle for very long: the observation interval lasting
-+	 * up to this dispatch cannot be a valid observation interval
-+	 * for computing a new peak rate (similarly to the late-
-+	 * completion event in bfq_completed_request()). Go to
-+	 * update_rate_and_reset to have the following three steps
-+	 * taken:
-+	 * - close the observation interval at the last (previous)
-+	 *   request dispatch or completion
-+	 * - compute rate, if possible, for that observation interval
-+	 * - start a new observation interval with this dispatch
-+	 */
-+	if (now_ns - bfqd->last_dispatch > 100*NSEC_PER_MSEC &&
-+	    bfqd->rq_in_driver == 0) {
-+		bfq_log(bfqd,
-+"update_peak_rate: jumping to updating&resetting delta_last %lluus samples %d",
-+			(now_ns - bfqd->last_dispatch)>>10,
-+			bfqd->peak_rate_samples) ;
-+		goto update_rate_and_reset;
-+	}
-+
-+	/* Update sampling information */
-+	bfqd->peak_rate_samples++;
-+
-+	if ((bfqd->rq_in_driver > 0 ||
-+		now_ns - bfqd->last_completion < BFQ_MIN_TT)
-+	     && get_sdist(bfqd->last_position, rq) < BFQQ_SEEK_THR)
-+		bfqd->sequential_samples++;
-+
-+	bfqd->tot_sectors_dispatched += blk_rq_sectors(rq);
-+
-+	/* Reset max observed rq size every 32 dispatches */
-+	if (likely(bfqd->peak_rate_samples % 32))
-+		bfqd->last_rq_max_size =
-+			max_t(u32, blk_rq_sectors(rq), bfqd->last_rq_max_size);
-+	else
-+		bfqd->last_rq_max_size = blk_rq_sectors(rq);
-+
-+	bfqd->delta_from_first = now_ns - bfqd->first_dispatch;
-+
-+	bfq_log(bfqd,
-+	"update_peak_rate: added samples %u/%u tot_sects %llu delta_first %lluus",
-+		bfqd->peak_rate_samples, bfqd->sequential_samples,
-+		bfqd->tot_sectors_dispatched,
-+		bfqd->delta_from_first>>10);
-+
-+	/* Target observation interval not yet reached, go on sampling */
-+	if (bfqd->delta_from_first < BFQ_RATE_REF_INTERVAL)
-+		goto update_last_values;
-+
-+update_rate_and_reset:
-+	bfq_update_rate_reset(bfqd, rq);
-+update_last_values:
-+	bfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
-+	bfqd->last_dispatch = now_ns;
-+
-+	bfq_log(bfqd,
-+	"update_peak_rate: delta_first %lluus last_pos %llu peak_rate %llu",
-+		(now_ns - bfqd->first_dispatch)>>10,
-+		(unsigned long long) bfqd->last_position,
-+		((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT));
-+	bfq_log(bfqd,
-+	"update_peak_rate: samples at end %d", bfqd->peak_rate_samples);
-+}
-+
-+/*
-+ * Move request from internal lists to the dispatch list of the request queue
-+ */
-+static void bfq_dispatch_insert(struct request_queue *q, struct request *rq)
-+{
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq);
-+
-+	/*
-+	 * For consistency, the next instruction should have been executed
-+	 * after removing the request from the queue and dispatching it.
-+	 * We execute instead this instruction before bfq_remove_request()
-+	 * (and hence introduce a temporary inconsistency), for efficiency.
-+	 * In fact, in a forced_dispatch, this prevents two counters related
-+	 * to bfqq->dispatched to risk to be uselessly decremented if bfqq
-+	 * is not in service, and then to be incremented again after
-+	 * incrementing bfqq->dispatched.
-+	 */
-+	bfqq->dispatched++;
-+	bfq_update_peak_rate(q->elevator->elevator_data, rq);
-+
-+	bfq_remove_request(rq);
-+	elv_dispatch_sort(q, rq);
-+}
-+
-+static void __bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	BUG_ON(bfqq != bfqd->in_service_queue);
-+
-+	/*
-+	 * If this bfqq is shared between multiple processes, check
-+	 * to make sure that those processes are still issuing I/Os
-+	 * within the mean seek distance. If not, it may be time to
-+	 * break the queues apart again.
-+	 */
-+	if (bfq_bfqq_coop(bfqq) && BFQQ_SEEKY(bfqq))
-+		bfq_mark_bfqq_split_coop(bfqq);
-+
-+	if (RB_EMPTY_ROOT(&bfqq->sort_list)) {
-+		if (bfqq->dispatched == 0)
-+			/*
-+			 * Overloading budget_timeout field to store
-+			 * the time at which the queue remains with no
-+			 * backlog and no outstanding request; used by
-+			 * the weight-raising mechanism.
-+			 */
-+			bfqq->budget_timeout = jiffies;
-+
-+		bfq_del_bfqq_busy(bfqd, bfqq, true);
-+	} else {
-+		bfq_requeue_bfqq(bfqd, bfqq);
-+		/*
-+		 * Resort priority tree of potential close cooperators.
-+		 */
-+		bfq_pos_tree_add_move(bfqd, bfqq);
-+	}
-+
-+	/*
-+	 * All in-service entities must have been properly deactivated
-+	 * or requeued before executing the next function, which
-+	 * resets all in-service entites as no more in service.
-+	 */
-+	__bfq_bfqd_reset_in_service(bfqd);
-+}
-+
-+/**
-+ * __bfq_bfqq_recalc_budget - try to adapt the budget to the @bfqq behavior.
-+ * @bfqd: device data.
-+ * @bfqq: queue to update.
-+ * @reason: reason for expiration.
-+ *
-+ * Handle the feedback on @bfqq budget at queue expiration.
-+ * See the body for detailed comments.
-+ */
-+static void __bfq_bfqq_recalc_budget(struct bfq_data *bfqd,
-+				     struct bfq_queue *bfqq,
-+				     enum bfqq_expiration reason)
-+{
-+	struct request *next_rq;
-+	int budget, min_budget;
-+
-+	BUG_ON(bfqq != bfqd->in_service_queue);
-+
-+	min_budget = bfq_min_budget(bfqd);
-+
-+	if (bfqq->wr_coeff == 1)
-+		budget = bfqq->max_budget;
-+	else /*
-+	      * Use a constant, low budget for weight-raised queues,
-+	      * to help achieve a low latency. Keep it slightly higher
-+	      * than the minimum possible budget, to cause a little
-+	      * bit fewer expirations.
-+	      */
-+		budget = 2 * min_budget;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last budg %d, budg left %d",
-+		bfqq->entity.budget, bfq_bfqq_budget_left(bfqq));
-+	bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last max_budg %d, min budg %d",
-+		budget, bfq_min_budget(bfqd));
-+	bfq_log_bfqq(bfqd, bfqq, "recalc_budg: sync %d, seeky %d",
-+		bfq_bfqq_sync(bfqq), BFQQ_SEEKY(bfqd->in_service_queue));
-+
-+	if (bfq_bfqq_sync(bfqq) && bfqq->wr_coeff == 1) {
-+		switch (reason) {
-+		/*
-+		 * Caveat: in all the following cases we trade latency
-+		 * for throughput.
-+		 */
-+		case BFQ_BFQQ_TOO_IDLE:
-+			/*
-+			 * This is the only case where we may reduce
-+			 * the budget: if there is no request of the
-+			 * process still waiting for completion, then
-+			 * we assume (tentatively) that the timer has
-+			 * expired because the batch of requests of
-+			 * the process could have been served with a
-+			 * smaller budget.  Hence, betting that
-+			 * process will behave in the same way when it
-+			 * becomes backlogged again, we reduce its
-+			 * next budget.  As long as we guess right,
-+			 * this budget cut reduces the latency
-+			 * experienced by the process.
-+			 *
-+			 * However, if there are still outstanding
-+			 * requests, then the process may have not yet
-+			 * issued its next request just because it is
-+			 * still waiting for the completion of some of
-+			 * the still outstanding ones.  So in this
-+			 * subcase we do not reduce its budget, on the
-+			 * contrary we increase it to possibly boost
-+			 * the throughput, as discussed in the
-+			 * comments to the BUDGET_TIMEOUT case.
-+			 */
-+			if (bfqq->dispatched > 0) /* still outstanding reqs */
-+				budget = min(budget * 2, bfqd->bfq_max_budget);
-+			else {
-+				if (budget > 5 * min_budget)
-+					budget -= 4 * min_budget;
-+				else
-+					budget = min_budget;
-+			}
-+			break;
-+		case BFQ_BFQQ_BUDGET_TIMEOUT:
-+			/*
-+			 * We double the budget here because it gives
-+			 * the chance to boost the throughput if this
-+			 * is not a seeky process (and has bumped into
-+			 * this timeout because of, e.g., ZBR).
-+			 */
-+			budget = min(budget * 2, bfqd->bfq_max_budget);
-+			break;
-+		case BFQ_BFQQ_BUDGET_EXHAUSTED:
-+			/*
-+			 * The process still has backlog, and did not
-+			 * let either the budget timeout or the disk
-+			 * idling timeout expire. Hence it is not
-+			 * seeky, has a short thinktime and may be
-+			 * happy with a higher budget too. So
-+			 * definitely increase the budget of this good
-+			 * candidate to boost the disk throughput.
-+			 */
-+			budget = min(budget * 4, bfqd->bfq_max_budget);
-+			break;
-+		case BFQ_BFQQ_NO_MORE_REQUESTS:
-+			/*
-+			 * For queues that expire for this reason, it
-+			 * is particularly important to keep the
-+			 * budget close to the actual service they
-+			 * need. Doing so reduces the timestamp
-+			 * misalignment problem described in the
-+			 * comments in the body of
-+			 * __bfq_activate_entity. In fact, suppose
-+			 * that a queue systematically expires for
-+			 * BFQ_BFQQ_NO_MORE_REQUESTS and presents a
-+			 * new request in time to enjoy timestamp
-+			 * back-shifting. The larger the budget of the
-+			 * queue is with respect to the service the
-+			 * queue actually requests in each service
-+			 * slot, the more times the queue can be
-+			 * reactivated with the same virtual finish
-+			 * time. It follows that, even if this finish
-+			 * time is pushed to the system virtual time
-+			 * to reduce the consequent timestamp
-+			 * misalignment, the queue unjustly enjoys for
-+			 * many re-activations a lower finish time
-+			 * than all newly activated queues.
-+			 *
-+			 * The service needed by bfqq is measured
-+			 * quite precisely by bfqq->entity.service.
-+			 * Since bfqq does not enjoy device idling,
-+			 * bfqq->entity.service is equal to the number
-+			 * of sectors that the process associated with
-+			 * bfqq requested to read/write before waiting
-+			 * for request completions, or blocking for
-+			 * other reasons.
-+			 */
-+			budget = max_t(int, bfqq->entity.service, min_budget);
-+			break;
-+		default:
-+			return;
-+		}
-+	} else if (!bfq_bfqq_sync(bfqq))
-+		/*
-+		 * Async queues get always the maximum possible
-+		 * budget, as for them we do not care about latency
-+		 * (in addition, their ability to dispatch is limited
-+		 * by the charging factor).
-+		 */
-+		budget = bfqd->bfq_max_budget;
-+
-+	bfqq->max_budget = budget;
-+
-+	if (bfqd->budgets_assigned >= bfq_stats_min_budgets &&
-+	    !bfqd->bfq_user_max_budget)
-+		bfqq->max_budget = min(bfqq->max_budget, bfqd->bfq_max_budget);
-+
-+	/*
-+	 * If there is still backlog, then assign a new budget, making
-+	 * sure that it is large enough for the next request.  Since
-+	 * the finish time of bfqq must be kept in sync with the
-+	 * budget, be sure to call __bfq_bfqq_expire() *after* this
-+	 * update.
-+	 *
-+	 * If there is no backlog, then no need to update the budget;
-+	 * it will be updated on the arrival of a new request.
-+	 */
-+	next_rq = bfqq->next_rq;
-+	if (next_rq) {
-+		BUG_ON(reason == BFQ_BFQQ_TOO_IDLE ||
-+		       reason == BFQ_BFQQ_NO_MORE_REQUESTS);
-+		bfqq->entity.budget = max_t(unsigned long, bfqq->max_budget,
-+					    bfq_serv_to_charge(next_rq, bfqq));
-+		BUG_ON(!bfq_bfqq_busy(bfqq));
-+		BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list));
-+	}
-+
-+	bfq_log_bfqq(bfqd, bfqq, "head sect: %u, new budget %d",
-+			next_rq ? blk_rq_sectors(next_rq) : 0,
-+			bfqq->entity.budget);
-+}
-+
-+/*
-+ * Return true if the process associated with bfqq is "slow". The slow
-+ * flag is used, in addition to the budget timeout, to reduce the
-+ * amount of service provided to seeky processes, and thus reduce
-+ * their chances to lower the throughput. More details in the comments
-+ * on the function bfq_bfqq_expire().
-+ *
-+ * An important observation is in order: as discussed in the comments
-+ * on the function bfq_update_peak_rate(), with devices with internal
-+ * queues, it is hard if ever possible to know when and for how long
-+ * an I/O request is processed by the device (apart from the trivial
-+ * I/O pattern where a new request is dispatched only after the
-+ * previous one has been completed). This makes it hard to evaluate
-+ * the real rate at which the I/O requests of each bfq_queue are
-+ * served.  In fact, for an I/O scheduler like BFQ, serving a
-+ * bfq_queue means just dispatching its requests during its service
-+ * slot (i.e., until the budget of the queue is exhausted, or the
-+ * queue remains idle, or, finally, a timeout fires). But, during the
-+ * service slot of a bfq_queue, around 100 ms at most, the device may
-+ * be even still processing requests of bfq_queues served in previous
-+ * service slots. On the opposite end, the requests of the in-service
-+ * bfq_queue may be completed after the service slot of the queue
-+ * finishes.
-+ *
-+ * Anyway, unless more sophisticated solutions are used
-+ * (where possible), the sum of the sizes of the requests dispatched
-+ * during the service slot of a bfq_queue is probably the only
-+ * approximation available for the service received by the bfq_queue
-+ * during its service slot. And this sum is the quantity used in this
-+ * function to evaluate the I/O speed of a process.
-+ */
-+static bool bfq_bfqq_is_slow(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+				 bool compensate, enum bfqq_expiration reason,
-+				 unsigned long *delta_ms)
-+{
-+	ktime_t delta_ktime;
-+	u32 delta_usecs;
-+	bool slow = BFQQ_SEEKY(bfqq); /* if delta too short, use seekyness */
-+
-+	if (!bfq_bfqq_sync(bfqq))
-+		return false;
-+
-+	if (compensate)
-+		delta_ktime = bfqd->last_idling_start;
-+	else
-+		delta_ktime = ktime_get();
-+	delta_ktime = ktime_sub(delta_ktime, bfqd->last_budget_start);
-+	delta_usecs = ktime_to_us(delta_ktime);
-+
-+	/* don't use too short time intervals */
-+	if (delta_usecs < 1000) {
-+		if (blk_queue_nonrot(bfqd->queue))
-+			 /*
-+			  * give same worst-case guarantees as idling
-+			  * for seeky
-+			  */
-+			*delta_ms = BFQ_MIN_TT / NSEC_PER_MSEC;
-+		else /* charge at least one seek */
-+			*delta_ms = bfq_slice_idle / NSEC_PER_MSEC;
-+
-+		bfq_log(bfqd, "bfq_bfqq_is_slow: too short %u", delta_usecs);
-+
-+		return slow;
-+	}
-+
-+	*delta_ms = delta_usecs / USEC_PER_MSEC;
-+
-+	/*
-+	 * Use only long (> 20ms) intervals to filter out excessive
-+	 * spikes in service rate estimation.
-+	 */
-+	if (delta_usecs > 20000) {
-+		/*
-+		 * Caveat for rotational devices: processes doing I/O
-+		 * in the slower disk zones tend to be slow(er) even
-+		 * if not seeky. In this respect, the estimated peak
-+		 * rate is likely to be an average over the disk
-+		 * surface. Accordingly, to not be too harsh with
-+		 * unlucky processes, a process is deemed slow only if
-+		 * its rate has been lower than half of the estimated
-+		 * peak rate.
-+		 */
-+		slow = bfqq->entity.service < bfqd->bfq_max_budget / 2;
-+		bfq_log(bfqd, "bfq_bfqq_is_slow: relative rate %d/%d",
-+			bfqq->entity.service, bfqd->bfq_max_budget);
-+	}
-+
-+	bfq_log_bfqq(bfqd, bfqq, "bfq_bfqq_is_slow: slow %d", slow);
-+
-+	return slow;
-+}
-+
-+/*
-+ * To be deemed as soft real-time, an application must meet two
-+ * requirements. First, the application must not require an average
-+ * bandwidth higher than the approximate bandwidth required to playback or
-+ * record a compressed high-definition video.
-+ * The next function is invoked on the completion of the last request of a
-+ * batch, to compute the next-start time instant, soft_rt_next_start, such
-+ * that, if the next request of the application does not arrive before
-+ * soft_rt_next_start, then the above requirement on the bandwidth is met.
-+ *
-+ * The second requirement is that the request pattern of the application is
-+ * isochronous, i.e., that, after issuing a request or a batch of requests,
-+ * the application stops issuing new requests until all its pending requests
-+ * have been completed. After that, the application may issue a new batch,
-+ * and so on.
-+ * For this reason the next function is invoked to compute
-+ * soft_rt_next_start only for applications that meet this requirement,
-+ * whereas soft_rt_next_start is set to infinity for applications that do
-+ * not.
-+ *
-+ * Unfortunately, even a greedy application may happen to behave in an
-+ * isochronous way if the CPU load is high. In fact, the application may
-+ * stop issuing requests while the CPUs are busy serving other processes,
-+ * then restart, then stop again for a while, and so on. In addition, if
-+ * the disk achieves a low enough throughput with the request pattern
-+ * issued by the application (e.g., because the request pattern is random
-+ * and/or the device is slow), then the application may meet the above
-+ * bandwidth requirement too. To prevent such a greedy application to be
-+ * deemed as soft real-time, a further rule is used in the computation of
-+ * soft_rt_next_start: soft_rt_next_start must be higher than the current
-+ * time plus the maximum time for which the arrival of a request is waited
-+ * for when a sync queue becomes idle, namely bfqd->bfq_slice_idle.
-+ * This filters out greedy applications, as the latter issue instead their
-+ * next request as soon as possible after the last one has been completed
-+ * (in contrast, when a batch of requests is completed, a soft real-time
-+ * application spends some time processing data).
-+ *
-+ * Unfortunately, the last filter may easily generate false positives if
-+ * only bfqd->bfq_slice_idle is used as a reference time interval and one
-+ * or both the following cases occur:
-+ * 1) HZ is so low that the duration of a jiffy is comparable to or higher
-+ *    than bfqd->bfq_slice_idle. This happens, e.g., on slow devices with
-+ *    HZ=100.
-+ * 2) jiffies, instead of increasing at a constant rate, may stop increasing
-+ *    for a while, then suddenly 'jump' by several units to recover the lost
-+ *    increments. This seems to happen, e.g., inside virtual machines.
-+ * To address this issue, we do not use as a reference time interval just
-+ * bfqd->bfq_slice_idle, but bfqd->bfq_slice_idle plus a few jiffies. In
-+ * particular we add the minimum number of jiffies for which the filter
-+ * seems to be quite precise also in embedded systems and KVM/QEMU virtual
-+ * machines.
-+ */
-+static unsigned long bfq_bfqq_softrt_next_start(struct bfq_data *bfqd,
-+						struct bfq_queue *bfqq)
-+{
-+	bfq_log_bfqq(bfqd, bfqq,
-+"softrt_next_start: service_blkg %lu soft_rate %u sects/sec interval %u",
-+		     bfqq->service_from_backlogged,
-+		     bfqd->bfq_wr_max_softrt_rate,
-+		     jiffies_to_msecs(HZ * bfqq->service_from_backlogged /
-+				      bfqd->bfq_wr_max_softrt_rate));
-+
-+	return max(bfqq->last_idle_bklogged +
-+		   HZ * bfqq->service_from_backlogged /
-+		   bfqd->bfq_wr_max_softrt_rate,
-+		   jiffies + nsecs_to_jiffies(bfqq->bfqd->bfq_slice_idle) + 4);
-+}
-+
-+/*
-+ * Return the farthest future time instant according to jiffies
-+ * macros.
-+ */
-+static unsigned long bfq_greatest_from_now(void)
-+{
-+	return jiffies + MAX_JIFFY_OFFSET;
-+}
-+
-+/*
-+ * Return the farthest past time instant according to jiffies
-+ * macros.
-+ */
-+static unsigned long bfq_smallest_from_now(void)
-+{
-+	return jiffies - MAX_JIFFY_OFFSET;
-+}
-+
-+/**
-+ * bfq_bfqq_expire - expire a queue.
-+ * @bfqd: device owning the queue.
-+ * @bfqq: the queue to expire.
-+ * @compensate: if true, compensate for the time spent idling.
-+ * @reason: the reason causing the expiration.
-+ *
-+ * If the process associated with bfqq does slow I/O (e.g., because it
-+ * issues random requests), we charge bfqq with the time it has been
-+ * in service instead of the service it has received (see
-+ * bfq_bfqq_charge_time for details on how this goal is achieved). As
-+ * a consequence, bfqq will typically get higher timestamps upon
-+ * reactivation, and hence it will be rescheduled as if it had
-+ * received more service than what it has actually received. In the
-+ * end, bfqq receives less service in proportion to how slowly its
-+ * associated process consumes its budgets (and hence how seriously it
-+ * tends to lower the throughput). In addition, this time-charging
-+ * strategy guarantees time fairness among slow processes. In
-+ * contrast, if the process associated with bfqq is not slow, we
-+ * charge bfqq exactly with the service it has received.
-+ *
-+ * Charging time to the first type of queues and the exact service to
-+ * the other has the effect of using the WF2Q+ policy to schedule the
-+ * former on a timeslice basis, without violating service domain
-+ * guarantees among the latter.
-+ */
-+static void bfq_bfqq_expire(struct bfq_data *bfqd,
-+			    struct bfq_queue *bfqq,
-+			    bool compensate,
-+			    enum bfqq_expiration reason)
-+{
-+	bool slow;
-+	unsigned long delta = 0;
-+	struct bfq_entity *entity = &bfqq->entity;
-+	int ref;
-+
-+	BUG_ON(bfqq != bfqd->in_service_queue);
-+
-+	/*
-+	 * Check whether the process is slow (see bfq_bfqq_is_slow).
-+	 */
-+	slow = bfq_bfqq_is_slow(bfqd, bfqq, compensate, reason, &delta);
-+
-+	/*
-+	 * Increase service_from_backlogged before next statement,
-+	 * because the possible next invocation of
-+	 * bfq_bfqq_charge_time would likely inflate
-+	 * entity->service. In contrast, service_from_backlogged must
-+	 * contain real service, to enable the soft real-time
-+	 * heuristic to correctly compute the bandwidth consumed by
-+	 * bfqq.
-+	 */
-+	bfqq->service_from_backlogged += entity->service;
-+
-+	/*
-+	 * As above explained, charge slow (typically seeky) and
-+	 * timed-out queues with the time and not the service
-+	 * received, to favor sequential workloads.
-+	 *
-+	 * Processes doing I/O in the slower disk zones will tend to
-+	 * be slow(er) even if not seeky. Therefore, since the
-+	 * estimated peak rate is actually an average over the disk
-+	 * surface, these processes may timeout just for bad luck. To
-+	 * avoid punishing them, do not charge time to processes that
-+	 * succeeded in consuming at least 2/3 of their budget. This
-+	 * allows BFQ to preserve enough elasticity to still perform
-+	 * bandwidth, and not time, distribution with little unlucky
-+	 * or quasi-sequential processes.
-+	 */
-+	if (bfqq->wr_coeff == 1 &&
-+	    (slow ||
-+	     (reason == BFQ_BFQQ_BUDGET_TIMEOUT &&
-+	      bfq_bfqq_budget_left(bfqq) >=  entity->budget / 3)))
-+		bfq_bfqq_charge_time(bfqd, bfqq, delta);
-+
-+	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
-+
-+	if (reason == BFQ_BFQQ_TOO_IDLE &&
-+	    entity->service <= 2 * entity->budget / 10)
-+		bfq_clear_bfqq_IO_bound(bfqq);
-+
-+	if (bfqd->low_latency && bfqq->wr_coeff == 1)
-+		bfqq->last_wr_start_finish = jiffies;
-+
-+	if (bfqd->low_latency && bfqd->bfq_wr_max_softrt_rate > 0 &&
-+	    RB_EMPTY_ROOT(&bfqq->sort_list)) {
-+		/*
-+		 * If we get here, and there are no outstanding
-+		 * requests, then the request pattern is isochronous
-+		 * (see the comments on the function
-+		 * bfq_bfqq_softrt_next_start()). Thus we can compute
-+		 * soft_rt_next_start. If, instead, the queue still
-+		 * has outstanding requests, then we have to wait for
-+		 * the completion of all the outstanding requests to
-+		 * discover whether the request pattern is actually
-+		 * isochronous.
-+		 */
-+		BUG_ON(bfqd->busy_queues < 1);
-+		if (bfqq->dispatched == 0) {
-+			bfqq->soft_rt_next_start =
-+				bfq_bfqq_softrt_next_start(bfqd, bfqq);
-+			bfq_log_bfqq(bfqd, bfqq, "new soft_rt_next %lu",
-+				     bfqq->soft_rt_next_start);
-+		} else {
-+			/*
-+			 * The application is still waiting for the
-+			 * completion of one or more requests:
-+			 * prevent it from possibly being incorrectly
-+			 * deemed as soft real-time by setting its
-+			 * soft_rt_next_start to infinity. In fact,
-+			 * without this assignment, the application
-+			 * would be incorrectly deemed as soft
-+			 * real-time if:
-+			 * 1) it issued a new request before the
-+			 *    completion of all its in-flight
-+			 *    requests, and
-+			 * 2) at that time, its soft_rt_next_start
-+			 *    happened to be in the past.
-+			 */
-+			bfqq->soft_rt_next_start =
-+				bfq_greatest_from_now();
-+			/*
-+			 * Schedule an update of soft_rt_next_start to when
-+			 * the task may be discovered to be isochronous.
-+			 */
-+			bfq_mark_bfqq_softrt_update(bfqq);
-+		}
-+	}
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+		"expire (%d, slow %d, num_disp %d, idle_win %d, weight %d)",
-+		     reason, slow, bfqq->dispatched,
-+		     bfq_bfqq_idle_window(bfqq), entity->weight);
-+
-+	/*
-+	 * Increase, decrease or leave budget unchanged according to
-+	 * reason.
-+	 */
-+	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
-+	__bfq_bfqq_recalc_budget(bfqd, bfqq, reason);
-+	BUG_ON(bfqq->next_rq == NULL &&
-+	       bfqq->entity.budget < bfqq->entity.service);
-+	ref = bfqq->ref;
-+	__bfq_bfqq_expire(bfqd, bfqq);
-+
-+	BUG_ON(ref > 1 &&
-+	       !bfq_bfqq_busy(bfqq) && reason == BFQ_BFQQ_BUDGET_EXHAUSTED &&
-+		!bfq_class_idle(bfqq));
-+
-+	/* mark bfqq as waiting a request only if a bic still points to it */
-+	if (ref > 1 && !bfq_bfqq_busy(bfqq) &&
-+	    reason != BFQ_BFQQ_BUDGET_TIMEOUT &&
-+	    reason != BFQ_BFQQ_BUDGET_EXHAUSTED)
-+		bfq_mark_bfqq_non_blocking_wait_rq(bfqq);
-+}
-+
-+/*
-+ * Budget timeout is not implemented through a dedicated timer, but
-+ * just checked on request arrivals and completions, as well as on
-+ * idle timer expirations.
-+ */
-+static bool bfq_bfqq_budget_timeout(struct bfq_queue *bfqq)
-+{
-+	return time_is_before_eq_jiffies(bfqq->budget_timeout);
-+}
-+
-+/*
-+ * If we expire a queue that is actively waiting (i.e., with the
-+ * device idled) for the arrival of a new request, then we may incur
-+ * the timestamp misalignment problem described in the body of the
-+ * function __bfq_activate_entity. Hence we return true only if this
-+ * condition does not hold, or if the queue is slow enough to deserve
-+ * only to be kicked off for preserving a high throughput.
-+ */
-+static bool bfq_may_expire_for_budg_timeout(struct bfq_queue *bfqq)
-+{
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		"may_budget_timeout: wait_request %d left %d timeout %d",
-+		bfq_bfqq_wait_request(bfqq),
-+			bfq_bfqq_budget_left(bfqq) >=  bfqq->entity.budget / 3,
-+		bfq_bfqq_budget_timeout(bfqq));
-+
-+	return (!bfq_bfqq_wait_request(bfqq) ||
-+		bfq_bfqq_budget_left(bfqq) >=  bfqq->entity.budget / 3)
-+		&&
-+		bfq_bfqq_budget_timeout(bfqq);
-+}
-+
-+/*
-+ * For a queue that becomes empty, device idling is allowed only if
-+ * this function returns true for that queue. As a consequence, since
-+ * device idling plays a critical role for both throughput boosting
-+ * and service guarantees, the return value of this function plays a
-+ * critical role as well.
-+ *
-+ * In a nutshell, this function returns true only if idling is
-+ * beneficial for throughput or, even if detrimental for throughput,
-+ * idling is however necessary to preserve service guarantees (low
-+ * latency, desired throughput distribution, ...). In particular, on
-+ * NCQ-capable devices, this function tries to return false, so as to
-+ * help keep the drives' internal queues full, whenever this helps the
-+ * device boost the throughput without causing any service-guarantee
-+ * issue.
-+ *
-+ * In more detail, the return value of this function is obtained by,
-+ * first, computing a number of boolean variables that take into
-+ * account throughput and service-guarantee issues, and, then,
-+ * combining these variables in a logical expression. Most of the
-+ * issues taken into account are not trivial. We discuss these issues
-+ * while introducing the variables.
-+ */
-+static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq)
-+{
-+	struct bfq_data *bfqd = bfqq->bfqd;
-+	bool idling_boosts_thr, idling_boosts_thr_without_issues,
-+		idling_needed_for_service_guarantees,
-+		asymmetric_scenario;
-+
-+	if (bfqd->strict_guarantees)
-+		return true;
-+
-+	/*
-+	 * The next variable takes into account the cases where idling
-+	 * boosts the throughput.
-+	 *
-+	 * The value of the variable is computed considering, first, that
-+	 * idling is virtually always beneficial for the throughput if:
-+	 * (a) the device is not NCQ-capable, or
-+	 * (b) regardless of the presence of NCQ, the device is rotational
-+	 *     and the request pattern for bfqq is I/O-bound and sequential.
-+	 *
-+	 * Secondly, and in contrast to the above item (b), idling an
-+	 * NCQ-capable flash-based device would not boost the
-+	 * throughput even with sequential I/O; rather it would lower
-+	 * the throughput in proportion to how fast the device
-+	 * is. Accordingly, the next variable is true if any of the
-+	 * above conditions (a) and (b) is true, and, in particular,
-+	 * happens to be false if bfqd is an NCQ-capable flash-based
-+	 * device.
-+	 */
-+	idling_boosts_thr = !bfqd->hw_tag ||
-+		(!blk_queue_nonrot(bfqd->queue) && bfq_bfqq_IO_bound(bfqq) &&
-+		 bfq_bfqq_idle_window(bfqq));
-+
-+	/*
-+	 * The value of the next variable,
-+	 * idling_boosts_thr_without_issues, is equal to that of
-+	 * idling_boosts_thr, unless a special case holds. In this
-+	 * special case, described below, idling may cause problems to
-+	 * weight-raised queues.
-+	 *
-+	 * When the request pool is saturated (e.g., in the presence
-+	 * of write hogs), if the processes associated with
-+	 * non-weight-raised queues ask for requests at a lower rate,
-+	 * then processes associated with weight-raised queues have a
-+	 * higher probability to get a request from the pool
-+	 * immediately (or at least soon) when they need one. Thus
-+	 * they have a higher probability to actually get a fraction
-+	 * of the device throughput proportional to their high
-+	 * weight. This is especially true with NCQ-capable drives,
-+	 * which enqueue several requests in advance, and further
-+	 * reorder internally-queued requests.
-+	 *
-+	 * For this reason, we force to false the value of
-+	 * idling_boosts_thr_without_issues if there are weight-raised
-+	 * busy queues. In this case, and if bfqq is not weight-raised,
-+	 * this guarantees that the device is not idled for bfqq (if,
-+	 * instead, bfqq is weight-raised, then idling will be
-+	 * guaranteed by another variable, see below). Combined with
-+	 * the timestamping rules of BFQ (see [1] for details), this
-+	 * behavior causes bfqq, and hence any sync non-weight-raised
-+	 * queue, to get a lower number of requests served, and thus
-+	 * to ask for a lower number of requests from the request
-+	 * pool, before the busy weight-raised queues get served
-+	 * again. This often mitigates starvation problems in the
-+	 * presence of heavy write workloads and NCQ, thereby
-+	 * guaranteeing a higher application and system responsiveness
-+	 * in these hostile scenarios.
-+	 */
-+	idling_boosts_thr_without_issues = idling_boosts_thr &&
-+		bfqd->wr_busy_queues == 0;
-+
-+	/*
-+	 * There is then a case where idling must be performed not
-+	 * for throughput concerns, but to preserve service
-+	 * guarantees.
-+	 *
-+	 * To introduce this case, we can note that allowing the drive
-+	 * to enqueue more than one request at a time, and hence
-+	 * delegating de facto final scheduling decisions to the
-+	 * drive's internal scheduler, entails loss of control on the
-+	 * actual request service order. In particular, the critical
-+	 * situation is when requests from different processes happen
-+	 * to be present, at the same time, in the internal queue(s)
-+	 * of the drive. In such a situation, the drive, by deciding
-+	 * the service order of the internally-queued requests, does
-+	 * determine also the actual throughput distribution among
-+	 * these processes. But the drive typically has no notion or
-+	 * concern about per-process throughput distribution, and
-+	 * makes its decisions only on a per-request basis. Therefore,
-+	 * the service distribution enforced by the drive's internal
-+	 * scheduler is likely to coincide with the desired
-+	 * device-throughput distribution only in a completely
-+	 * symmetric scenario where:
-+	 * (i)  each of these processes must get the same throughput as
-+	 *      the others;
-+	 * (ii) all these processes have the same I/O pattern
-+	 *      (either sequential or random).
-+	 * In fact, in such a scenario, the drive will tend to treat
-+	 * the requests of each of these processes in about the same
-+	 * way as the requests of the others, and thus to provide
-+	 * each of these processes with about the same throughput
-+	 * (which is exactly the desired throughput distribution). In
-+	 * contrast, in any asymmetric scenario, device idling is
-+	 * certainly needed to guarantee that bfqq receives its
-+	 * assigned fraction of the device throughput (see [1] for
-+	 * details).
-+	 *
-+	 * We address this issue by controlling, actually, only the
-+	 * symmetry sub-condition (i), i.e., provided that
-+	 * sub-condition (i) holds, idling is not performed,
-+	 * regardless of whether sub-condition (ii) holds. In other
-+	 * words, only if sub-condition (i) holds, then idling is
-+	 * allowed, and the device tends to be prevented from queueing
-+	 * many requests, possibly of several processes. The reason
-+	 * for not controlling also sub-condition (ii) is that we
-+	 * exploit preemption to preserve guarantees in case of
-+	 * symmetric scenarios, even if (ii) does not hold, as
-+	 * explained in the next two paragraphs.
-+	 *
-+	 * Even if a queue, say Q, is expired when it remains idle, Q
-+	 * can still preempt the new in-service queue if the next
-+	 * request of Q arrives soon (see the comments on
-+	 * bfq_bfqq_update_budg_for_activation). If all queues and
-+	 * groups have the same weight, this form of preemption,
-+	 * combined with the hole-recovery heuristic described in the
-+	 * comments on function bfq_bfqq_update_budg_for_activation,
-+	 * are enough to preserve a correct bandwidth distribution in
-+	 * the mid term, even without idling. In fact, even if not
-+	 * idling allows the internal queues of the device to contain
-+	 * many requests, and thus to reorder requests, we can rather
-+	 * safely assume that the internal scheduler still preserves a
-+	 * minimum of mid-term fairness. The motivation for using
-+	 * preemption instead of idling is that, by not idling,
-+	 * service guarantees are preserved without minimally
-+	 * sacrificing throughput. In other words, both a high
-+	 * throughput and its desired distribution are obtained.
-+	 *
-+	 * More precisely, this preemption-based, idleless approach
-+	 * provides fairness in terms of IOPS, and not sectors per
-+	 * second. This can be seen with a simple example. Suppose
-+	 * that there are two queues with the same weight, but that
-+	 * the first queue receives requests of 8 sectors, while the
-+	 * second queue receives requests of 1024 sectors. In
-+	 * addition, suppose that each of the two queues contains at
-+	 * most one request at a time, which implies that each queue
-+	 * always remains idle after it is served. Finally, after
-+	 * remaining idle, each queue receives very quickly a new
-+	 * request. It follows that the two queues are served
-+	 * alternatively, preempting each other if needed. This
-+	 * implies that, although both queues have the same weight,
-+	 * the queue with large requests receives a service that is
-+	 * 1024/8 times as high as the service received by the other
-+	 * queue.
-+	 *
-+	 * On the other hand, device idling is performed, and thus
-+	 * pure sector-domain guarantees are provided, for the
-+	 * following queues, which are likely to need stronger
-+	 * throughput guarantees: weight-raised queues, and queues
-+	 * with a higher weight than other queues. When such queues
-+	 * are active, sub-condition (i) is false, which triggers
-+	 * device idling.
-+	 *
-+	 * According to the above considerations, the next variable is
-+	 * true (only) if sub-condition (i) holds. To compute the
-+	 * value of this variable, we not only use the return value of
-+	 * the function bfq_symmetric_scenario(), but also check
-+	 * whether bfqq is being weight-raised, because
-+	 * bfq_symmetric_scenario() does not take into account also
-+	 * weight-raised queues (see comments on
-+	 * bfq_weights_tree_add()).
-+	 *
-+	 * As a side note, it is worth considering that the above
-+	 * device-idling countermeasures may however fail in the
-+	 * following unlucky scenario: if idling is (correctly)
-+	 * disabled in a time period during which all symmetry
-+	 * sub-conditions hold, and hence the device is allowed to
-+	 * enqueue many requests, but at some later point in time some
-+	 * sub-condition stops to hold, then it may become impossible
-+	 * to let requests be served in the desired order until all
-+	 * the requests already queued in the device have been served.
-+	 */
-+	asymmetric_scenario = bfqq->wr_coeff > 1 ||
-+		!bfq_symmetric_scenario(bfqd);
-+
-+	/*
-+	 * Finally, there is a case where maximizing throughput is the
-+	 * best choice even if it may cause unfairness toward
-+	 * bfqq. Such a case is when bfqq became active in a burst of
-+	 * queue activations. Queues that became active during a large
-+	 * burst benefit only from throughput, as discussed in the
-+	 * comments on bfq_handle_burst. Thus, if bfqq became active
-+	 * in a burst and not idling the device maximizes throughput,
-+	 * then the device must no be idled, because not idling the
-+	 * device provides bfqq and all other queues in the burst with
-+	 * maximum benefit. Combining this and the above case, we can
-+	 * now establish when idling is actually needed to preserve
-+	 * service guarantees.
-+	 */
-+	idling_needed_for_service_guarantees =
-+		asymmetric_scenario && !bfq_bfqq_in_large_burst(bfqq);
-+
-+	/*
-+	 * We have now all the components we need to compute the return
-+	 * value of the function, which is true only if both the following
-+	 * conditions hold:
-+	 * 1) bfqq is sync, because idling make sense only for sync queues;
-+	 * 2) idling either boosts the throughput (without issues), or
-+	 *    is necessary to preserve service guarantees.
-+	 */
-+	bfq_log_bfqq(bfqd, bfqq, "may_idle: sync %d idling_boosts_thr %d",
-+		     bfq_bfqq_sync(bfqq), idling_boosts_thr);
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+		     "may_idle: wr_busy %d boosts %d IO-bound %d guar %d",
-+		     bfqd->wr_busy_queues,
-+		     idling_boosts_thr_without_issues,
-+		     bfq_bfqq_IO_bound(bfqq),
-+		     idling_needed_for_service_guarantees);
-+
-+	return bfq_bfqq_sync(bfqq) &&
-+		(idling_boosts_thr_without_issues ||
-+		 idling_needed_for_service_guarantees);
-+}
-+
-+/*
-+ * If the in-service queue is empty but the function bfq_bfqq_may_idle
-+ * returns true, then:
-+ * 1) the queue must remain in service and cannot be expired, and
-+ * 2) the device must be idled to wait for the possible arrival of a new
-+ *    request for the queue.
-+ * See the comments on the function bfq_bfqq_may_idle for the reasons
-+ * why performing device idling is the best choice to boost the throughput
-+ * and preserve service guarantees when bfq_bfqq_may_idle itself
-+ * returns true.
-+ */
-+static bool bfq_bfqq_must_idle(struct bfq_queue *bfqq)
-+{
-+	struct bfq_data *bfqd = bfqq->bfqd;
-+
-+	return RB_EMPTY_ROOT(&bfqq->sort_list) && bfqd->bfq_slice_idle != 0 &&
-+	       bfq_bfqq_may_idle(bfqq);
-+}
-+
-+/*
-+ * Select a queue for service.  If we have a current queue in service,
-+ * check whether to continue servicing it, or retrieve and set a new one.
-+ */
-+static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd)
-+{
-+	struct bfq_queue *bfqq;
-+	struct request *next_rq;
-+	enum bfqq_expiration reason = BFQ_BFQQ_BUDGET_TIMEOUT;
-+
-+	bfqq = bfqd->in_service_queue;
-+	if (!bfqq)
-+		goto new_queue;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "select_queue: already in-service queue");
-+
-+	if (bfq_may_expire_for_budg_timeout(bfqq) &&
-+	    !hrtimer_active(&bfqd->idle_slice_timer) &&
-+	    !bfq_bfqq_must_idle(bfqq))
-+		goto expire;
-+
-+check_queue:
-+	/*
-+	 * This loop is rarely executed more than once. Even when it
-+	 * happens, it is much more convenient to re-execute this loop
-+	 * than to return NULL and trigger a new dispatch to get a
-+	 * request served.
-+	 */
-+	next_rq = bfqq->next_rq;
-+	/*
-+	 * If bfqq has requests queued and it has enough budget left to
-+	 * serve them, keep the queue, otherwise expire it.
-+	 */
-+	if (next_rq) {
-+		BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list));
-+
-+		if (bfq_serv_to_charge(next_rq, bfqq) >
-+			bfq_bfqq_budget_left(bfqq)) {
-+			/*
-+			 * Expire the queue for budget exhaustion,
-+			 * which makes sure that the next budget is
-+			 * enough to serve the next request, even if
-+			 * it comes from the fifo expired path.
-+			 */
-+			reason = BFQ_BFQQ_BUDGET_EXHAUSTED;
-+			goto expire;
-+		} else {
-+			/*
-+			 * The idle timer may be pending because we may
-+			 * not disable disk idling even when a new request
-+			 * arrives.
-+			 */
-+			if (bfq_bfqq_wait_request(bfqq)) {
-+				BUG_ON(!hrtimer_active(&bfqd->idle_slice_timer));
-+				/*
-+				 * If we get here: 1) at least a new request
-+				 * has arrived but we have not disabled the
-+				 * timer because the request was too small,
-+				 * 2) then the block layer has unplugged
-+				 * the device, causing the dispatch to be
-+				 * invoked.
-+				 *
-+				 * Since the device is unplugged, now the
-+				 * requests are probably large enough to
-+				 * provide a reasonable throughput.
-+				 * So we disable idling.
-+				 */
-+				bfq_clear_bfqq_wait_request(bfqq);
-+				hrtimer_try_to_cancel(&bfqd->idle_slice_timer);
-+				bfqg_stats_update_idle_time(bfqq_group(bfqq));
-+			}
-+			goto keep_queue;
-+		}
-+	}
-+
-+	/*
-+	 * No requests pending. However, if the in-service queue is idling
-+	 * for a new request, or has requests waiting for a completion and
-+	 * may idle after their completion, then keep it anyway.
-+	 */
-+	if (hrtimer_active(&bfqd->idle_slice_timer) ||
-+	    (bfqq->dispatched != 0 && bfq_bfqq_may_idle(bfqq))) {
-+		bfqq = NULL;
-+		goto keep_queue;
-+	}
-+
-+	reason = BFQ_BFQQ_NO_MORE_REQUESTS;
-+expire:
-+	bfq_bfqq_expire(bfqd, bfqq, false, reason);
-+new_queue:
-+	bfqq = bfq_set_in_service_queue(bfqd);
-+	if (bfqq) {
-+		bfq_log_bfqq(bfqd, bfqq, "select_queue: checking new queue");
-+		goto check_queue;
-+	}
-+keep_queue:
-+	if (bfqq)
-+		bfq_log_bfqq(bfqd, bfqq, "select_queue: returned this queue");
-+	else
-+		bfq_log(bfqd, "select_queue: no queue returned");
-+
-+	return bfqq;
-+}
-+
-+static void bfq_update_wr_data(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+
-+	if (bfqq->wr_coeff > 1) { /* queue is being weight-raised */
-+		BUG_ON(bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time &&
-+		       time_is_after_jiffies(bfqq->last_wr_start_finish));
-+
-+		bfq_log_bfqq(bfqd, bfqq,
-+			"raising period dur %u/%u msec, old coeff %u, w %d(%d)",
-+			jiffies_to_msecs(jiffies - bfqq->last_wr_start_finish),
-+			jiffies_to_msecs(bfqq->wr_cur_max_time),
-+			bfqq->wr_coeff,
-+			bfqq->entity.weight, bfqq->entity.orig_weight);
-+
-+		BUG_ON(bfqq != bfqd->in_service_queue && entity->weight !=
-+		       entity->orig_weight * bfqq->wr_coeff);
-+		if (entity->prio_changed)
-+			bfq_log_bfqq(bfqd, bfqq, "WARN: pending prio change");
-+
-+		/*
-+		 * If the queue was activated in a burst, or too much
-+		 * time has elapsed from the beginning of this
-+		 * weight-raising period, then end weight raising.
-+		 */
-+		if (bfq_bfqq_in_large_burst(bfqq))
-+			bfq_bfqq_end_wr(bfqq);
-+		else if (time_is_before_jiffies(bfqq->last_wr_start_finish +
-+					   bfqq->wr_cur_max_time)) {
-+			if (bfqq->wr_cur_max_time != bfqd->bfq_wr_rt_max_time ||
-+			time_is_before_jiffies(bfqq->wr_start_at_switch_to_srt +
-+					bfq_wr_duration(bfqd)))
-+				bfq_bfqq_end_wr(bfqq);
-+			else {
-+				/* switch back to interactive wr */
-+				bfqq->wr_coeff = bfqd->bfq_wr_coeff;
-+				bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
-+				bfqq->last_wr_start_finish =
-+					bfqq->wr_start_at_switch_to_srt;
-+				BUG_ON(time_is_after_jiffies(
-+					       bfqq->last_wr_start_finish));
-+				bfqq->entity.prio_changed = 1;
-+				bfq_log_bfqq(bfqd, bfqq,
-+					"back to interactive wr");
-+			}
-+		}
-+	}
-+	/*
-+	 * To improve latency (for this or other queues), immediately
-+	 * update weight both if it must be raised and if it must be
-+	 * lowered. Since, entity may be on some active tree here, and
-+	 * might have a pending change of its ioprio class, invoke
-+	 * next function with the last parameter unset (see the
-+	 * comments on the function).
-+	 */
-+	if ((entity->weight > entity->orig_weight) != (bfqq->wr_coeff > 1))
-+		__bfq_entity_update_weight_prio(bfq_entity_service_tree(entity),
-+						entity, false);
-+}
-+
-+/*
-+ * Dispatch one request from bfqq, moving it to the request queue
-+ * dispatch list.
-+ */
-+static int bfq_dispatch_request(struct bfq_data *bfqd,
-+				struct bfq_queue *bfqq)
-+{
-+	int dispatched = 0;
-+	struct request *rq = bfqq->next_rq;
-+	unsigned long service_to_charge;
-+
-+	BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list));
-+	BUG_ON(!rq);
-+	service_to_charge = bfq_serv_to_charge(rq, bfqq);
-+
-+	BUG_ON(service_to_charge > bfq_bfqq_budget_left(bfqq));
-+
-+	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
-+
-+	bfq_bfqq_served(bfqq, service_to_charge);
-+
-+	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
-+
-+	bfq_dispatch_insert(bfqd->queue, rq);
-+
-+	/*
-+	 * If weight raising has to terminate for bfqq, then next
-+	 * function causes an immediate update of bfqq's weight,
-+	 * without waiting for next activation. As a consequence, on
-+	 * expiration, bfqq will be timestamped as if has never been
-+	 * weight-raised during this service slot, even if it has
-+	 * received part or even most of the service as a
-+	 * weight-raised queue. This inflates bfqq's timestamps, which
-+	 * is beneficial, as bfqq is then more willing to leave the
-+	 * device immediately to possible other weight-raised queues.
-+	 */
-+	bfq_update_wr_data(bfqd, bfqq);
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+			"dispatched %u sec req (%llu), budg left %d",
-+			blk_rq_sectors(rq),
-+			(unsigned long long) blk_rq_pos(rq),
-+			bfq_bfqq_budget_left(bfqq));
-+
-+	dispatched++;
-+
-+	if (!bfqd->in_service_bic) {
-+		atomic_long_inc(&RQ_BIC(rq)->icq.ioc->refcount);
-+		bfqd->in_service_bic = RQ_BIC(rq);
-+	}
-+
-+	if (bfqd->busy_queues > 1 && bfq_class_idle(bfqq))
-+		goto expire;
-+
-+	return dispatched;
-+
-+expire:
-+	bfq_bfqq_expire(bfqd, bfqq, false, BFQ_BFQQ_BUDGET_EXHAUSTED);
-+	return dispatched;
-+}
-+
-+static int __bfq_forced_dispatch_bfqq(struct bfq_queue *bfqq)
-+{
-+	int dispatched = 0;
-+
-+	while (bfqq->next_rq) {
-+		bfq_dispatch_insert(bfqq->bfqd->queue, bfqq->next_rq);
-+		dispatched++;
-+	}
-+
-+	BUG_ON(!list_empty(&bfqq->fifo));
-+	return dispatched;
-+}
-+
-+/*
-+ * Drain our current requests.
-+ * Used for barriers and when switching io schedulers on-the-fly.
-+ */
-+static int bfq_forced_dispatch(struct bfq_data *bfqd)
-+{
-+	struct bfq_queue *bfqq, *n;
-+	struct bfq_service_tree *st;
-+	int dispatched = 0;
-+
-+	bfqq = bfqd->in_service_queue;
-+	if (bfqq)
-+		__bfq_bfqq_expire(bfqd, bfqq);
-+
-+	/*
-+	 * Loop through classes, and be careful to leave the scheduler
-+	 * in a consistent state, as feedback mechanisms and vtime
-+	 * updates cannot be disabled during the process.
-+	 */
-+	list_for_each_entry_safe(bfqq, n, &bfqd->active_list, bfqq_list) {
-+		st = bfq_entity_service_tree(&bfqq->entity);
-+
-+		dispatched += __bfq_forced_dispatch_bfqq(bfqq);
-+
-+		bfqq->max_budget = bfq_max_budget(bfqd);
-+		bfq_forget_idle(st);
-+	}
-+
-+	BUG_ON(bfqd->busy_queues != 0);
-+
-+	return dispatched;
-+}
-+
-+static int bfq_dispatch_requests(struct request_queue *q, int force)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	struct bfq_queue *bfqq;
-+
-+	bfq_log(bfqd, "dispatch requests: %d busy queues", bfqd->busy_queues);
-+
-+	if (bfqd->busy_queues == 0)
-+		return 0;
-+
-+	if (unlikely(force))
-+		return bfq_forced_dispatch(bfqd);
-+
-+	/*
-+	 * Force device to serve one request at a time if
-+	 * strict_guarantees is true. Forcing this service scheme is
-+	 * currently the ONLY way to guarantee that the request
-+	 * service order enforced by the scheduler is respected by a
-+	 * queueing device. Otherwise the device is free even to make
-+	 * some unlucky request wait for as long as the device
-+	 * wishes.
-+	 *
-+	 * Of course, serving one request at at time may cause loss of
-+	 * throughput.
-+	 */
-+	if (bfqd->strict_guarantees && bfqd->rq_in_driver > 0)
-+		return 0;
-+
-+	bfqq = bfq_select_queue(bfqd);
-+	if (!bfqq)
-+		return 0;
-+
-+	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
-+
-+	BUG_ON(bfq_bfqq_wait_request(bfqq));
-+
-+	if (!bfq_dispatch_request(bfqd, bfqq))
-+		return 0;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "dispatched %s request",
-+			bfq_bfqq_sync(bfqq) ? "sync" : "async");
-+
-+	BUG_ON(bfqq->next_rq == NULL &&
-+	       bfqq->entity.budget < bfqq->entity.service);
-+	return 1;
-+}
-+
-+/*
-+ * Task holds one reference to the queue, dropped when task exits.  Each rq
-+ * in-flight on this queue also holds a reference, dropped when rq is freed.
-+ *
-+ * Queue lock must be held here. Recall not to use bfqq after calling
-+ * this function on it.
-+ */
-+static void bfq_put_queue(struct bfq_queue *bfqq)
-+{
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	struct bfq_group *bfqg = bfqq_group(bfqq);
-+#endif
-+
-+	BUG_ON(bfqq->ref <= 0);
-+
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "put_queue: %p %d", bfqq, bfqq->ref);
-+	bfqq->ref--;
-+	if (bfqq->ref)
-+		return;
-+
-+	BUG_ON(rb_first(&bfqq->sort_list));
-+	BUG_ON(bfqq->allocated[READ] + bfqq->allocated[WRITE] != 0);
-+	BUG_ON(bfqq->entity.tree);
-+	BUG_ON(bfq_bfqq_busy(bfqq));
-+
-+	if (bfq_bfqq_sync(bfqq))
-+		/*
-+		 * The fact that this queue is being destroyed does not
-+		 * invalidate the fact that this queue may have been
-+		 * activated during the current burst. As a consequence,
-+		 * although the queue does not exist anymore, and hence
-+		 * needs to be removed from the burst list if there,
-+		 * the burst size has not to be decremented.
-+		 */
-+		hlist_del_init(&bfqq->burst_list_node);
-+
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "put_queue: %p freed", bfqq);
-+
-+	kmem_cache_free(bfq_pool, bfqq);
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	bfqg_put(bfqg);
-+#endif
-+}
-+
-+static void bfq_put_cooperator(struct bfq_queue *bfqq)
-+{
-+	struct bfq_queue *__bfqq, *next;
-+
-+	/*
-+	 * If this queue was scheduled to merge with another queue, be
-+	 * sure to drop the reference taken on that queue (and others in
-+	 * the merge chain). See bfq_setup_merge and bfq_merge_bfqqs.
-+	 */
-+	__bfqq = bfqq->new_bfqq;
-+	while (__bfqq) {
-+		if (__bfqq == bfqq)
-+			break;
-+		next = __bfqq->new_bfqq;
-+		bfq_put_queue(__bfqq);
-+		__bfqq = next;
-+	}
-+}
-+
-+static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	if (bfqq == bfqd->in_service_queue) {
-+		__bfq_bfqq_expire(bfqd, bfqq);
-+		bfq_schedule_dispatch(bfqd);
-+	}
-+
-+	bfq_log_bfqq(bfqd, bfqq, "exit_bfqq: %p, %d", bfqq, bfqq->ref);
-+
-+	bfq_put_cooperator(bfqq);
-+
-+	bfq_put_queue(bfqq); /* release process reference */
-+}
-+
-+static void bfq_init_icq(struct io_cq *icq)
-+{
-+	icq_to_bic(icq)->ttime.last_end_request = ktime_get_ns() - (1ULL<<32);
-+}
-+
-+static void bfq_exit_icq(struct io_cq *icq)
-+{
-+	struct bfq_io_cq *bic = icq_to_bic(icq);
-+	struct bfq_data *bfqd = bic_to_bfqd(bic);
-+
-+	if (bic_to_bfqq(bic, false)) {
-+		bfq_exit_bfqq(bfqd, bic_to_bfqq(bic, false));
-+		bic_set_bfqq(bic, NULL, false);
-+	}
-+
-+	if (bic_to_bfqq(bic, true)) {
-+		/*
-+		 * If the bic is using a shared queue, put the reference
-+		 * taken on the io_context when the bic started using a
-+		 * shared bfq_queue.
-+		 */
-+		if (bfq_bfqq_coop(bic_to_bfqq(bic, true)))
-+			put_io_context(icq->ioc);
-+		bfq_exit_bfqq(bfqd, bic_to_bfqq(bic, true));
-+		bic_set_bfqq(bic, NULL, true);
-+	}
-+}
-+
-+/*
-+ * Update the entity prio values; note that the new values will not
-+ * be used until the next (re)activation.
-+ */
-+static void bfq_set_next_ioprio_data(struct bfq_queue *bfqq,
-+				     struct bfq_io_cq *bic)
-+{
-+	struct task_struct *tsk = current;
-+	int ioprio_class;
-+
-+	ioprio_class = IOPRIO_PRIO_CLASS(bic->ioprio);
-+	switch (ioprio_class) {
-+	default:
-+		dev_err(bfqq->bfqd->queue->backing_dev_info->dev,
-+			"bfq: bad prio class %d\n", ioprio_class);
-+	case IOPRIO_CLASS_NONE:
-+		/*
-+		 * No prio set, inherit CPU scheduling settings.
-+		 */
-+		bfqq->new_ioprio = task_nice_ioprio(tsk);
-+		bfqq->new_ioprio_class = task_nice_ioclass(tsk);
-+		break;
-+	case IOPRIO_CLASS_RT:
-+		bfqq->new_ioprio = IOPRIO_PRIO_DATA(bic->ioprio);
-+		bfqq->new_ioprio_class = IOPRIO_CLASS_RT;
-+		break;
-+	case IOPRIO_CLASS_BE:
-+		bfqq->new_ioprio = IOPRIO_PRIO_DATA(bic->ioprio);
-+		bfqq->new_ioprio_class = IOPRIO_CLASS_BE;
-+		break;
-+	case IOPRIO_CLASS_IDLE:
-+		bfqq->new_ioprio_class = IOPRIO_CLASS_IDLE;
-+		bfqq->new_ioprio = 7;
-+		bfq_clear_bfqq_idle_window(bfqq);
-+		break;
-+	}
-+
-+	if (bfqq->new_ioprio >= IOPRIO_BE_NR) {
-+		pr_crit("bfq_set_next_ioprio_data: new_ioprio %d\n",
-+			bfqq->new_ioprio);
-+		BUG();
-+	}
-+
-+	bfqq->entity.new_weight = bfq_ioprio_to_weight(bfqq->new_ioprio);
-+	bfqq->entity.prio_changed = 1;
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		     "set_next_ioprio_data: bic_class %d prio %d class %d",
-+		     ioprio_class, bfqq->new_ioprio, bfqq->new_ioprio_class);
-+}
-+
-+static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio)
-+{
-+	struct bfq_data *bfqd = bic_to_bfqd(bic);
-+	struct bfq_queue *bfqq;
-+	unsigned long uninitialized_var(flags);
-+	int ioprio = bic->icq.ioc->ioprio;
-+
-+	/*
-+	 * This condition may trigger on a newly created bic, be sure to
-+	 * drop the lock before returning.
-+	 */
-+	if (unlikely(!bfqd) || likely(bic->ioprio == ioprio))
-+		return;
-+
-+	bic->ioprio = ioprio;
-+
-+	bfqq = bic_to_bfqq(bic, false);
-+	if (bfqq) {
-+		/* release process reference on this queue */
-+		bfq_put_queue(bfqq);
-+		bfqq = bfq_get_queue(bfqd, bio, BLK_RW_ASYNC, bic);
-+		bic_set_bfqq(bic, bfqq, false);
-+		bfq_log_bfqq(bfqd, bfqq,
-+			     "check_ioprio_change: bfqq %p %d",
-+			     bfqq, bfqq->ref);
-+	}
-+
-+	bfqq = bic_to_bfqq(bic, true);
-+	if (bfqq)
-+		bfq_set_next_ioprio_data(bfqq, bic);
-+}
-+
-+static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+			  struct bfq_io_cq *bic, pid_t pid, int is_sync)
-+{
-+	RB_CLEAR_NODE(&bfqq->entity.rb_node);
-+	INIT_LIST_HEAD(&bfqq->fifo);
-+	INIT_HLIST_NODE(&bfqq->burst_list_node);
-+	BUG_ON(!hlist_unhashed(&bfqq->burst_list_node));
-+
-+	bfqq->ref = 0;
-+	bfqq->bfqd = bfqd;
-+
-+	if (bic)
-+		bfq_set_next_ioprio_data(bfqq, bic);
-+
-+	if (is_sync) {
-+		if (!bfq_class_idle(bfqq))
-+			bfq_mark_bfqq_idle_window(bfqq);
-+		bfq_mark_bfqq_sync(bfqq);
-+		bfq_mark_bfqq_just_created(bfqq);
-+	} else
-+		bfq_clear_bfqq_sync(bfqq);
-+	bfq_mark_bfqq_IO_bound(bfqq);
-+
-+	/* Tentative initial value to trade off between thr and lat */
-+	bfqq->max_budget = (2 * bfq_max_budget(bfqd)) / 3;
-+	bfqq->pid = pid;
-+
-+	bfqq->wr_coeff = 1;
-+	bfqq->last_wr_start_finish = jiffies;
-+	bfqq->wr_start_at_switch_to_srt = bfq_smallest_from_now();
-+	bfqq->budget_timeout = bfq_smallest_from_now();
-+	bfqq->split_time = bfq_smallest_from_now();
-+
-+	/*
-+	 * Set to the value for which bfqq will not be deemed as
-+	 * soft rt when it becomes backlogged.
-+	 */
-+	bfqq->soft_rt_next_start = bfq_greatest_from_now();
-+
-+	/* first request is almost certainly seeky */
-+	bfqq->seek_history = 1;
-+}
-+
-+static struct bfq_queue **bfq_async_queue_prio(struct bfq_data *bfqd,
-+					       struct bfq_group *bfqg,
-+					       int ioprio_class, int ioprio)
-+{
-+	switch (ioprio_class) {
-+	case IOPRIO_CLASS_RT:
-+		return &bfqg->async_bfqq[0][ioprio];
-+	case IOPRIO_CLASS_NONE:
-+		ioprio = IOPRIO_NORM;
-+		/* fall through */
-+	case IOPRIO_CLASS_BE:
-+		return &bfqg->async_bfqq[1][ioprio];
-+	case IOPRIO_CLASS_IDLE:
-+		return &bfqg->async_idle_bfqq;
-+	default:
-+		BUG();
-+	}
-+}
-+
-+static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd,
-+				       struct bio *bio, bool is_sync,
-+				       struct bfq_io_cq *bic)
-+{
-+	const int ioprio = IOPRIO_PRIO_DATA(bic->ioprio);
-+	const int ioprio_class = IOPRIO_PRIO_CLASS(bic->ioprio);
-+	struct bfq_queue **async_bfqq = NULL;
-+	struct bfq_queue *bfqq;
-+	struct bfq_group *bfqg;
-+
-+	rcu_read_lock();
-+
-+	bfqg = bfq_find_set_group(bfqd, bio_blkcg(bio));
-+	if (!bfqg) {
-+		bfqq = &bfqd->oom_bfqq;
-+		goto out;
-+	}
-+
-+	if (!is_sync) {
-+		async_bfqq = bfq_async_queue_prio(bfqd, bfqg, ioprio_class,
-+						  ioprio);
-+		bfqq = *async_bfqq;
-+		if (bfqq)
-+			goto out;
-+	}
-+
-+	bfqq = kmem_cache_alloc_node(bfq_pool,
-+				     GFP_NOWAIT | __GFP_ZERO | __GFP_NOWARN,
-+				     bfqd->queue->node);
-+
-+	if (bfqq) {
-+		bfq_init_bfqq(bfqd, bfqq, bic, current->pid,
-+			      is_sync);
-+		bfq_init_entity(&bfqq->entity, bfqg);
-+		bfq_log_bfqq(bfqd, bfqq, "allocated");
-+	} else {
-+		bfqq = &bfqd->oom_bfqq;
-+		bfq_log_bfqq(bfqd, bfqq, "using oom bfqq");
-+		goto out;
-+	}
-+
-+	/*
-+	 * Pin the queue now that it's allocated, scheduler exit will
-+	 * prune it.
-+	 */
-+	if (async_bfqq) {
-+		bfqq->ref++; /*
-+			      * Extra group reference, w.r.t. sync
-+			      * queue. This extra reference is removed
-+			      * only if bfqq->bfqg disappears, to
-+			      * guarantee that this queue is not freed
-+			      * until its group goes away.
-+			      */
-+		bfq_log_bfqq(bfqd, bfqq, "get_queue, bfqq not in async: %p, %d",
-+			     bfqq, bfqq->ref);
-+		*async_bfqq = bfqq;
-+	}
-+
-+out:
-+	bfqq->ref++; /* get a process reference to this queue */
-+	bfq_log_bfqq(bfqd, bfqq, "get_queue, at end: %p, %d", bfqq, bfqq->ref);
-+	rcu_read_unlock();
-+	return bfqq;
-+}
-+
-+static void bfq_update_io_thinktime(struct bfq_data *bfqd,
-+				    struct bfq_io_cq *bic)
-+{
-+	struct bfq_ttime *ttime = &bic->ttime;
-+	u64 elapsed = ktime_get_ns() - bic->ttime.last_end_request;
-+
-+	elapsed = min_t(u64, elapsed, 2 * bfqd->bfq_slice_idle);
-+
-+	ttime->ttime_samples = (7*bic->ttime.ttime_samples + 256) / 8;
-+	ttime->ttime_total = div_u64(7*ttime->ttime_total + 256*elapsed,  8);
-+	ttime->ttime_mean = div64_ul(ttime->ttime_total + 128,
-+				     ttime->ttime_samples);
-+}
-+
-+static void
-+bfq_update_io_seektime(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+		       struct request *rq)
-+{
-+	bfqq->seek_history <<= 1;
-+	bfqq->seek_history |=
-+		get_sdist(bfqq->last_request_pos, rq) > BFQQ_SEEK_THR &&
-+		(!blk_queue_nonrot(bfqd->queue) ||
-+		 blk_rq_sectors(rq) < BFQQ_SECT_THR_NONROT);
-+}
-+
-+/*
-+ * Disable idle window if the process thinks too long or seeks so much that
-+ * it doesn't matter.
-+ */
-+static void bfq_update_idle_window(struct bfq_data *bfqd,
-+				   struct bfq_queue *bfqq,
-+				   struct bfq_io_cq *bic)
-+{
-+	int enable_idle;
-+
-+	/* Don't idle for async or idle io prio class. */
-+	if (!bfq_bfqq_sync(bfqq) || bfq_class_idle(bfqq))
-+		return;
-+
-+	/* Idle window just restored, statistics are meaningless. */
-+	if (time_is_after_eq_jiffies(bfqq->split_time +
-+				     bfqd->bfq_wr_min_idle_time))
-+		return;
-+
-+	enable_idle = bfq_bfqq_idle_window(bfqq);
-+
-+	if (atomic_read(&bic->icq.ioc->active_ref) == 0 ||
-+	    bfqd->bfq_slice_idle == 0 ||
-+		(bfqd->hw_tag && BFQQ_SEEKY(bfqq) &&
-+			bfqq->wr_coeff == 1))
-+		enable_idle = 0;
-+	else if (bfq_sample_valid(bic->ttime.ttime_samples)) {
-+		if (bic->ttime.ttime_mean > bfqd->bfq_slice_idle &&
-+			bfqq->wr_coeff == 1)
-+			enable_idle = 0;
-+		else
-+			enable_idle = 1;
-+	}
-+	bfq_log_bfqq(bfqd, bfqq, "update_idle_window: enable_idle %d",
-+		enable_idle);
-+
-+	if (enable_idle)
-+		bfq_mark_bfqq_idle_window(bfqq);
-+	else
-+		bfq_clear_bfqq_idle_window(bfqq);
-+}
-+
-+/*
-+ * Called when a new fs request (rq) is added to bfqq.  Check if there's
-+ * something we should do about it.
-+ */
-+static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+			    struct request *rq)
-+{
-+	struct bfq_io_cq *bic = RQ_BIC(rq);
-+
-+	if (rq->cmd_flags & REQ_META)
-+		bfqq->meta_pending++;
-+
-+	bfq_update_io_thinktime(bfqd, bic);
-+	bfq_update_io_seektime(bfqd, bfqq, rq);
-+	if (bfqq->entity.service > bfq_max_budget(bfqd) / 8 ||
-+	    !BFQQ_SEEKY(bfqq))
-+		bfq_update_idle_window(bfqd, bfqq, bic);
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+		     "rq_enqueued: idle_window=%d (seeky %d)",
-+		     bfq_bfqq_idle_window(bfqq), BFQQ_SEEKY(bfqq));
-+
-+	bfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
-+
-+	if (bfqq == bfqd->in_service_queue && bfq_bfqq_wait_request(bfqq)) {
-+		bool small_req = bfqq->queued[rq_is_sync(rq)] == 1 &&
-+				 blk_rq_sectors(rq) < 32;
-+		bool budget_timeout = bfq_bfqq_budget_timeout(bfqq);
-+
-+		/*
-+		 * There is just this request queued: if the request
-+		 * is small and the queue is not to be expired, then
-+		 * just exit.
-+		 *
-+		 * In this way, if the device is being idled to wait
-+		 * for a new request from the in-service queue, we
-+		 * avoid unplugging the device and committing the
-+		 * device to serve just a small request. On the
-+		 * contrary, we wait for the block layer to decide
-+		 * when to unplug the device: hopefully, new requests
-+		 * will be merged to this one quickly, then the device
-+		 * will be unplugged and larger requests will be
-+		 * dispatched.
-+		 */
-+		if (small_req && !budget_timeout)
-+			return;
-+
-+		/*
-+		 * A large enough request arrived, or the queue is to
-+		 * be expired: in both cases disk idling is to be
-+		 * stopped, so clear wait_request flag and reset
-+		 * timer.
-+		 */
-+		bfq_clear_bfqq_wait_request(bfqq);
-+		hrtimer_try_to_cancel(&bfqd->idle_slice_timer);
-+		bfqg_stats_update_idle_time(bfqq_group(bfqq));
-+
-+		/*
-+		 * The queue is not empty, because a new request just
-+		 * arrived. Hence we can safely expire the queue, in
-+		 * case of budget timeout, without risking that the
-+		 * timestamps of the queue are not updated correctly.
-+		 * See [1] for more details.
-+		 */
-+		if (budget_timeout)
-+			bfq_bfqq_expire(bfqd, bfqq, false,
-+					BFQ_BFQQ_BUDGET_TIMEOUT);
-+
-+		/*
-+		 * Let the request rip immediately, or let a new queue be
-+		 * selected if bfqq has just been expired.
-+		 */
-+		__blk_run_queue(bfqd->queue);
-+	}
-+}
-+
-+static void bfq_insert_request(struct request_queue *q, struct request *rq)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq), *new_bfqq;
-+
-+	assert_spin_locked(bfqd->queue->queue_lock);
-+
-+	/*
-+	 * An unplug may trigger a requeue of a request from the device
-+	 * driver: make sure we are in process context while trying to
-+	 * merge two bfq_queues.
-+	 */
-+	if (!in_interrupt()) {
-+		new_bfqq = bfq_setup_cooperator(bfqd, bfqq, rq, true);
-+		if (new_bfqq) {
-+			if (bic_to_bfqq(RQ_BIC(rq), 1) != bfqq)
-+				new_bfqq = bic_to_bfqq(RQ_BIC(rq), 1);
-+			/*
-+			 * Release the request's reference to the old bfqq
-+			 * and make sure one is taken to the shared queue.
-+			 */
-+			new_bfqq->allocated[rq_data_dir(rq)]++;
-+			bfqq->allocated[rq_data_dir(rq)]--;
-+			new_bfqq->ref++;
-+			bfq_clear_bfqq_just_created(bfqq);
-+			if (bic_to_bfqq(RQ_BIC(rq), 1) == bfqq)
-+				bfq_merge_bfqqs(bfqd, RQ_BIC(rq),
-+						bfqq, new_bfqq);
-+			/*
-+			 * rq is about to be enqueued into new_bfqq,
-+			 * release rq reference on bfqq
-+			 */
-+			bfq_put_queue(bfqq);
-+			rq->elv.priv[1] = new_bfqq;
-+			bfqq = new_bfqq;
-+		}
-+	}
-+
-+	bfq_add_request(rq);
-+
-+	rq->fifo_time = ktime_get_ns() + bfqd->bfq_fifo_expire[rq_is_sync(rq)];
-+	list_add_tail(&rq->queuelist, &bfqq->fifo);
-+
-+	bfq_rq_enqueued(bfqd, bfqq, rq);
-+}
-+
-+static void bfq_update_hw_tag(struct bfq_data *bfqd)
-+{
-+	bfqd->max_rq_in_driver = max_t(int, bfqd->max_rq_in_driver,
-+				       bfqd->rq_in_driver);
-+
-+	if (bfqd->hw_tag == 1)
-+		return;
-+
-+	/*
-+	 * This sample is valid if the number of outstanding requests
-+	 * is large enough to allow a queueing behavior.  Note that the
-+	 * sum is not exact, as it's not taking into account deactivated
-+	 * requests.
-+	 */
-+	if (bfqd->rq_in_driver + bfqd->queued < BFQ_HW_QUEUE_THRESHOLD)
-+		return;
-+
-+	if (bfqd->hw_tag_samples++ < BFQ_HW_QUEUE_SAMPLES)
-+		return;
-+
-+	bfqd->hw_tag = bfqd->max_rq_in_driver > BFQ_HW_QUEUE_THRESHOLD;
-+	bfqd->max_rq_in_driver = 0;
-+	bfqd->hw_tag_samples = 0;
-+}
-+
-+static void bfq_completed_request(struct request_queue *q, struct request *rq)
-+{
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq);
-+	struct bfq_data *bfqd = bfqq->bfqd;
-+	u64 now_ns;
-+	u32 delta_us;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "completed one req with %u sects left",
-+		     blk_rq_sectors(rq));
-+
-+	assert_spin_locked(bfqd->queue->queue_lock);
-+	bfq_update_hw_tag(bfqd);
-+
-+	BUG_ON(!bfqd->rq_in_driver);
-+	BUG_ON(!bfqq->dispatched);
-+	bfqd->rq_in_driver--;
-+	bfqq->dispatched--;
-+	bfqg_stats_update_completion(bfqq_group(bfqq),
-+				     rq_start_time_ns(rq),
-+				     rq_io_start_time_ns(rq),
-+				     rq->cmd_flags);
-+
-+	if (!bfqq->dispatched && !bfq_bfqq_busy(bfqq)) {
-+		BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list));
-+		/*
-+		 * Set budget_timeout (which we overload to store the
-+		 * time at which the queue remains with no backlog and
-+		 * no outstanding request; used by the weight-raising
-+		 * mechanism).
-+		 */
-+		bfqq->budget_timeout = jiffies;
-+
-+		bfq_weights_tree_remove(bfqd, &bfqq->entity,
-+					&bfqd->queue_weights_tree);
-+	}
-+
-+	now_ns = ktime_get_ns();
-+
-+	RQ_BIC(rq)->ttime.last_end_request = now_ns;
-+
-+	/*
-+	 * Using us instead of ns, to get a reasonable precision in
-+	 * computing rate in next check.
-+	 */
-+	delta_us = div_u64(now_ns - bfqd->last_completion, NSEC_PER_USEC);
-+
-+	bfq_log(bfqd, "rq_completed: delta %uus/%luus max_size %u rate %llu/%llu",
-+		delta_us, BFQ_MIN_TT/NSEC_PER_USEC, bfqd->last_rq_max_size,
-+		(USEC_PER_SEC*
-+		(u64)((bfqd->last_rq_max_size<<BFQ_RATE_SHIFT)/delta_us))
-+			>>BFQ_RATE_SHIFT,
-+		(USEC_PER_SEC*(u64)(1UL<<(BFQ_RATE_SHIFT-10)))>>BFQ_RATE_SHIFT);
-+
-+	/*
-+	 * If the request took rather long to complete, and, according
-+	 * to the maximum request size recorded, this completion latency
-+	 * implies that the request was certainly served at a very low
-+	 * rate (less than 1M sectors/sec), then the whole observation
-+	 * interval that lasts up to this time instant cannot be a
-+	 * valid time interval for computing a new peak rate.  Invoke
-+	 * bfq_update_rate_reset to have the following three steps
-+	 * taken:
-+	 * - close the observation interval at the last (previous)
-+	 *   request dispatch or completion
-+	 * - compute rate, if possible, for that observation interval
-+	 * - reset to zero samples, which will trigger a proper
-+	 *   re-initialization of the observation interval on next
-+	 *   dispatch
-+	 */
-+	if (delta_us > BFQ_MIN_TT/NSEC_PER_USEC &&
-+	   (bfqd->last_rq_max_size<<BFQ_RATE_SHIFT)/delta_us <
-+			1UL<<(BFQ_RATE_SHIFT - 10))
-+		bfq_update_rate_reset(bfqd, NULL);
-+	bfqd->last_completion = now_ns;
-+
-+	/*
-+	 * If we are waiting to discover whether the request pattern
-+	 * of the task associated with the queue is actually
-+	 * isochronous, and both requisites for this condition to hold
-+	 * are now satisfied, then compute soft_rt_next_start (see the
-+	 * comments on the function bfq_bfqq_softrt_next_start()). We
-+	 * schedule this delayed check when bfqq expires, if it still
-+	 * has in-flight requests.
-+	 */
-+	if (bfq_bfqq_softrt_update(bfqq) && bfqq->dispatched == 0 &&
-+	    RB_EMPTY_ROOT(&bfqq->sort_list))
-+		bfqq->soft_rt_next_start =
-+			bfq_bfqq_softrt_next_start(bfqd, bfqq);
-+
-+	/*
-+	 * If this is the in-service queue, check if it needs to be expired,
-+	 * or if we want to idle in case it has no pending requests.
-+	 */
-+	if (bfqd->in_service_queue == bfqq) {
-+		if (bfqq->dispatched == 0 && bfq_bfqq_must_idle(bfqq)) {
-+			bfq_arm_slice_timer(bfqd);
-+			goto out;
-+		} else if (bfq_may_expire_for_budg_timeout(bfqq))
-+			bfq_bfqq_expire(bfqd, bfqq, false,
-+					BFQ_BFQQ_BUDGET_TIMEOUT);
-+		else if (RB_EMPTY_ROOT(&bfqq->sort_list) &&
-+			 (bfqq->dispatched == 0 ||
-+			  !bfq_bfqq_may_idle(bfqq)))
-+			bfq_bfqq_expire(bfqd, bfqq, false,
-+					BFQ_BFQQ_NO_MORE_REQUESTS);
-+	}
-+
-+	if (!bfqd->rq_in_driver)
-+		bfq_schedule_dispatch(bfqd);
-+
-+out:
-+	return;
-+}
-+
-+static int __bfq_may_queue(struct bfq_queue *bfqq)
-+{
-+	if (bfq_bfqq_wait_request(bfqq) && bfq_bfqq_must_alloc(bfqq)) {
-+		bfq_clear_bfqq_must_alloc(bfqq);
-+		return ELV_MQUEUE_MUST;
-+	}
-+
-+	return ELV_MQUEUE_MAY;
-+}
-+
-+static int bfq_may_queue(struct request_queue *q, unsigned int op)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	struct task_struct *tsk = current;
-+	struct bfq_io_cq *bic;
-+	struct bfq_queue *bfqq;
-+
-+	/*
-+	 * Don't force setup of a queue from here, as a call to may_queue
-+	 * does not necessarily imply that a request actually will be
-+	 * queued. So just lookup a possibly existing queue, or return
-+	 * 'may queue' if that fails.
-+	 */
-+	bic = bfq_bic_lookup(bfqd, tsk->io_context);
-+	if (!bic)
-+		return ELV_MQUEUE_MAY;
-+
-+	bfqq = bic_to_bfqq(bic, op_is_sync(op));
-+	if (bfqq)
-+		return __bfq_may_queue(bfqq);
-+
-+	return ELV_MQUEUE_MAY;
-+}
-+
-+/*
-+ * Queue lock held here.
-+ */
-+static void bfq_put_request(struct request *rq)
-+{
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq);
-+
-+	if (bfqq) {
-+		const int rw = rq_data_dir(rq);
-+
-+		BUG_ON(!bfqq->allocated[rw]);
-+		bfqq->allocated[rw]--;
-+
-+		rq->elv.priv[0] = NULL;
-+		rq->elv.priv[1] = NULL;
-+
-+		bfq_log_bfqq(bfqq->bfqd, bfqq, "put_request %p, %d",
-+			     bfqq, bfqq->ref);
-+		bfq_put_queue(bfqq);
-+	}
-+}
-+
-+/*
-+ * Returns NULL if a new bfqq should be allocated, or the old bfqq if this
-+ * was the last process referring to that bfqq.
-+ */
-+static struct bfq_queue *
-+bfq_split_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq)
-+{
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "splitting queue");
-+
-+	put_io_context(bic->icq.ioc);
-+
-+	if (bfqq_process_refs(bfqq) == 1) {
-+		bfqq->pid = current->pid;
-+		bfq_clear_bfqq_coop(bfqq);
-+		bfq_clear_bfqq_split_coop(bfqq);
-+		return bfqq;
-+	}
-+
-+	bic_set_bfqq(bic, NULL, 1);
-+
-+	bfq_put_cooperator(bfqq);
-+
-+	bfq_put_queue(bfqq);
-+	return NULL;
-+}
-+
-+/*
-+ * Allocate bfq data structures associated with this request.
-+ */
-+static int bfq_set_request(struct request_queue *q, struct request *rq,
-+			   struct bio *bio, gfp_t gfp_mask)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	struct bfq_io_cq *bic = icq_to_bic(rq->elv.icq);
-+	const int rw = rq_data_dir(rq);
-+	const int is_sync = rq_is_sync(rq);
-+	struct bfq_queue *bfqq;
-+	unsigned long flags;
-+	bool bfqq_already_existing = false, split = false;
-+
-+	spin_lock_irqsave(q->queue_lock, flags);
-+
-+	if (!bic)
-+		goto queue_fail;
-+
-+	bfq_check_ioprio_change(bic, bio);
-+
-+	bfq_bic_update_cgroup(bic, bio);
-+
-+new_queue:
-+	bfqq = bic_to_bfqq(bic, is_sync);
-+	if (!bfqq || bfqq == &bfqd->oom_bfqq) {
-+		if (bfqq)
-+			bfq_put_queue(bfqq);
-+		bfqq = bfq_get_queue(bfqd, bio, is_sync, bic);
-+		BUG_ON(!hlist_unhashed(&bfqq->burst_list_node));
-+
-+		bic_set_bfqq(bic, bfqq, is_sync);
-+		if (split && is_sync) {
-+			bfq_log_bfqq(bfqd, bfqq,
-+				     "set_request: was_in_list %d "
-+				     "was_in_large_burst %d "
-+				     "large burst in progress %d",
-+				     bic->was_in_burst_list,
-+				     bic->saved_in_large_burst,
-+				     bfqd->large_burst);
-+
-+			if ((bic->was_in_burst_list && bfqd->large_burst) ||
-+			    bic->saved_in_large_burst) {
-+				bfq_log_bfqq(bfqd, bfqq,
-+					     "set_request: marking in "
-+					     "large burst");
-+				bfq_mark_bfqq_in_large_burst(bfqq);
-+			} else {
-+				bfq_log_bfqq(bfqd, bfqq,
-+					     "set_request: clearing in "
-+					     "large burst");
-+				bfq_clear_bfqq_in_large_burst(bfqq);
-+				if (bic->was_in_burst_list)
-+					hlist_add_head(&bfqq->burst_list_node,
-+						       &bfqd->burst_list);
-+			}
-+			bfqq->split_time = jiffies;
-+		}
-+	} else {
-+		/* If the queue was seeky for too long, break it apart. */
-+		if (bfq_bfqq_coop(bfqq) && bfq_bfqq_split_coop(bfqq)) {
-+			bfq_log_bfqq(bfqd, bfqq, "breaking apart bfqq");
-+
-+			/* Update bic before losing reference to bfqq */
-+			if (bfq_bfqq_in_large_burst(bfqq))
-+				bic->saved_in_large_burst = true;
-+
-+			bfqq = bfq_split_bfqq(bic, bfqq);
-+			split = true;
-+			if (!bfqq)
-+				goto new_queue;
-+			else
-+				bfqq_already_existing = true;
-+		}
-+	}
-+
-+	bfqq->allocated[rw]++;
-+	bfqq->ref++;
-+	bfq_log_bfqq(bfqd, bfqq, "set_request: bfqq %p, %d", bfqq, bfqq->ref);
-+
-+	rq->elv.priv[0] = bic;
-+	rq->elv.priv[1] = bfqq;
-+
-+	/*
-+	 * If a bfq_queue has only one process reference, it is owned
-+	 * by only one bfq_io_cq: we can set the bic field of the
-+	 * bfq_queue to the address of that structure. Also, if the
-+	 * queue has just been split, mark a flag so that the
-+	 * information is available to the other scheduler hooks.
-+	 */
-+	if (likely(bfqq != &bfqd->oom_bfqq) && bfqq_process_refs(bfqq) == 1) {
-+		bfqq->bic = bic;
-+		if (split) {
-+			/*
-+			 * If the queue has just been split from a shared
-+			 * queue, restore the idle window and the possible
-+			 * weight raising period.
-+			 */
-+			bfq_bfqq_resume_state(bfqq, bfqd, bic,
-+					      bfqq_already_existing);
-+		}
-+	}
-+
-+	if (unlikely(bfq_bfqq_just_created(bfqq)))
-+		bfq_handle_burst(bfqd, bfqq);
-+
-+	spin_unlock_irqrestore(q->queue_lock, flags);
-+
-+	return 0;
-+
-+queue_fail:
-+	bfq_schedule_dispatch(bfqd);
-+	spin_unlock_irqrestore(q->queue_lock, flags);
-+
-+	return 1;
-+}
-+
-+static void bfq_kick_queue(struct work_struct *work)
-+{
-+	struct bfq_data *bfqd =
-+		container_of(work, struct bfq_data, unplug_work);
-+	struct request_queue *q = bfqd->queue;
-+
-+	spin_lock_irq(q->queue_lock);
-+	__blk_run_queue(q);
-+	spin_unlock_irq(q->queue_lock);
-+}
-+
-+/*
-+ * Handler of the expiration of the timer running if the in-service queue
-+ * is idling inside its time slice.
-+ */
-+static enum hrtimer_restart bfq_idle_slice_timer(struct hrtimer *timer)
-+{
-+	struct bfq_data *bfqd = container_of(timer, struct bfq_data,
-+					     idle_slice_timer);
-+	struct bfq_queue *bfqq;
-+	unsigned long flags;
-+	enum bfqq_expiration reason;
-+
-+	spin_lock_irqsave(bfqd->queue->queue_lock, flags);
-+
-+	bfqq = bfqd->in_service_queue;
-+	/*
-+	 * Theoretical race here: the in-service queue can be NULL or
-+	 * different from the queue that was idling if the timer handler
-+	 * spins on the queue_lock and a new request arrives for the
-+	 * current queue and there is a full dispatch cycle that changes
-+	 * the in-service queue.  This can hardly happen, but in the worst
-+	 * case we just expire a queue too early.
-+	 */
-+	if (bfqq) {
-+		bfq_log_bfqq(bfqd, bfqq, "slice_timer expired");
-+		bfq_clear_bfqq_wait_request(bfqq);
-+
-+		if (bfq_bfqq_budget_timeout(bfqq))
-+			/*
-+			 * Also here the queue can be safely expired
-+			 * for budget timeout without wasting
-+			 * guarantees
-+			 */
-+			reason = BFQ_BFQQ_BUDGET_TIMEOUT;
-+		else if (bfqq->queued[0] == 0 && bfqq->queued[1] == 0)
-+			/*
-+			 * The queue may not be empty upon timer expiration,
-+			 * because we may not disable the timer when the
-+			 * first request of the in-service queue arrives
-+			 * during disk idling.
-+			 */
-+			reason = BFQ_BFQQ_TOO_IDLE;
-+		else
-+			goto schedule_dispatch;
-+
-+		bfq_bfqq_expire(bfqd, bfqq, true, reason);
-+	}
-+
-+schedule_dispatch:
-+	bfq_schedule_dispatch(bfqd);
-+
-+	spin_unlock_irqrestore(bfqd->queue->queue_lock, flags);
-+	return HRTIMER_NORESTART;
-+}
-+
-+static void bfq_shutdown_timer_wq(struct bfq_data *bfqd)
-+{
-+	hrtimer_cancel(&bfqd->idle_slice_timer);
-+	cancel_work_sync(&bfqd->unplug_work);
-+}
-+
-+static void __bfq_put_async_bfqq(struct bfq_data *bfqd,
-+				 struct bfq_queue **bfqq_ptr)
-+{
-+	struct bfq_group *root_group = bfqd->root_group;
-+	struct bfq_queue *bfqq = *bfqq_ptr;
-+
-+	bfq_log(bfqd, "put_async_bfqq: %p", bfqq);
-+	if (bfqq) {
-+		bfq_bfqq_move(bfqd, bfqq, root_group);
-+		bfq_log_bfqq(bfqd, bfqq, "put_async_bfqq: putting %p, %d",
-+			     bfqq, bfqq->ref);
-+		bfq_put_queue(bfqq);
-+		*bfqq_ptr = NULL;
-+	}
-+}
-+
-+/*
-+ * Release all the bfqg references to its async queues.  If we are
-+ * deallocating the group these queues may still contain requests, so
-+ * we reparent them to the root cgroup (i.e., the only one that will
-+ * exist for sure until all the requests on a device are gone).
-+ */
-+static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg)
-+{
-+	int i, j;
-+
-+	for (i = 0; i < 2; i++)
-+		for (j = 0; j < IOPRIO_BE_NR; j++)
-+			__bfq_put_async_bfqq(bfqd, &bfqg->async_bfqq[i][j]);
-+
-+	__bfq_put_async_bfqq(bfqd, &bfqg->async_idle_bfqq);
-+}
-+
-+static void bfq_exit_queue(struct elevator_queue *e)
-+{
-+	struct bfq_data *bfqd = e->elevator_data;
-+	struct request_queue *q = bfqd->queue;
-+	struct bfq_queue *bfqq, *n;
-+
-+	bfq_shutdown_timer_wq(bfqd);
-+
-+	spin_lock_irq(q->queue_lock);
-+
-+	BUG_ON(bfqd->in_service_queue);
-+	list_for_each_entry_safe(bfqq, n, &bfqd->idle_list, bfqq_list)
-+		bfq_deactivate_bfqq(bfqd, bfqq, false, false);
-+
-+	spin_unlock_irq(q->queue_lock);
-+
-+	bfq_shutdown_timer_wq(bfqd);
-+
-+	BUG_ON(hrtimer_active(&bfqd->idle_slice_timer));
-+
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	blkcg_deactivate_policy(q, &blkcg_policy_bfq);
-+#else
-+	bfq_put_async_queues(bfqd, bfqd->root_group);
-+	kfree(bfqd->root_group);
-+#endif
-+
-+	kfree(bfqd);
-+}
-+
-+static void bfq_init_root_group(struct bfq_group *root_group,
-+				struct bfq_data *bfqd)
-+{
-+	int i;
-+
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	root_group->entity.parent = NULL;
-+	root_group->my_entity = NULL;
-+	root_group->bfqd = bfqd;
-+#endif
-+	root_group->rq_pos_tree = RB_ROOT;
-+	for (i = 0; i < BFQ_IOPRIO_CLASSES; i++)
-+		root_group->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT;
-+	root_group->sched_data.bfq_class_idle_last_service = jiffies;
-+}
-+
-+static int bfq_init_queue(struct request_queue *q, struct elevator_type *e)
-+{
-+	struct bfq_data *bfqd;
-+	struct elevator_queue *eq;
-+
-+	eq = elevator_alloc(q, e);
-+	if (!eq)
-+		return -ENOMEM;
-+
-+	bfqd = kzalloc_node(sizeof(*bfqd), GFP_KERNEL, q->node);
-+	if (!bfqd) {
-+		kobject_put(&eq->kobj);
-+		return -ENOMEM;
-+	}
-+	eq->elevator_data = bfqd;
-+
-+	/*
-+	 * Our fallback bfqq if bfq_find_alloc_queue() runs into OOM issues.
-+	 * Grab a permanent reference to it, so that the normal code flow
-+	 * will not attempt to free it.
-+	 */
-+	bfq_init_bfqq(bfqd, &bfqd->oom_bfqq, NULL, 1, 0);
-+	bfqd->oom_bfqq.ref++;
-+	bfqd->oom_bfqq.new_ioprio = BFQ_DEFAULT_QUEUE_IOPRIO;
-+	bfqd->oom_bfqq.new_ioprio_class = IOPRIO_CLASS_BE;
-+	bfqd->oom_bfqq.entity.new_weight =
-+		bfq_ioprio_to_weight(bfqd->oom_bfqq.new_ioprio);
-+
-+	/* oom_bfqq does not participate to bursts */
-+	bfq_clear_bfqq_just_created(&bfqd->oom_bfqq);
-+	/*
-+	 * Trigger weight initialization, according to ioprio, at the
-+	 * oom_bfqq's first activation. The oom_bfqq's ioprio and ioprio
-+	 * class won't be changed any more.
-+	 */
-+	bfqd->oom_bfqq.entity.prio_changed = 1;
-+
-+	bfqd->queue = q;
-+
-+	spin_lock_irq(q->queue_lock);
-+	q->elevator = eq;
-+	spin_unlock_irq(q->queue_lock);
-+
-+	bfqd->root_group = bfq_create_group_hierarchy(bfqd, q->node);
-+	if (!bfqd->root_group)
-+		goto out_free;
-+	bfq_init_root_group(bfqd->root_group, bfqd);
-+	bfq_init_entity(&bfqd->oom_bfqq.entity, bfqd->root_group);
-+
-+	hrtimer_init(&bfqd->idle_slice_timer, CLOCK_MONOTONIC,
-+		     HRTIMER_MODE_REL);
-+	bfqd->idle_slice_timer.function = bfq_idle_slice_timer;
-+
-+	bfqd->queue_weights_tree = RB_ROOT;
-+	bfqd->group_weights_tree = RB_ROOT;
-+
-+	INIT_WORK(&bfqd->unplug_work, bfq_kick_queue);
-+
-+	INIT_LIST_HEAD(&bfqd->active_list);
-+	INIT_LIST_HEAD(&bfqd->idle_list);
-+	INIT_HLIST_HEAD(&bfqd->burst_list);
-+
-+	bfqd->hw_tag = -1;
-+
-+	bfqd->bfq_max_budget = bfq_default_max_budget;
-+
-+	bfqd->bfq_fifo_expire[0] = bfq_fifo_expire[0];
-+	bfqd->bfq_fifo_expire[1] = bfq_fifo_expire[1];
-+	bfqd->bfq_back_max = bfq_back_max;
-+	bfqd->bfq_back_penalty = bfq_back_penalty;
-+	bfqd->bfq_slice_idle = bfq_slice_idle;
-+	bfqd->bfq_timeout = bfq_timeout;
-+
-+	bfqd->bfq_requests_within_timer = 120;
-+
-+	bfqd->bfq_large_burst_thresh = 8;
-+	bfqd->bfq_burst_interval = msecs_to_jiffies(180);
-+
-+	bfqd->low_latency = true;
-+
-+	/*
-+	 * Trade-off between responsiveness and fairness.
-+	 */
-+	bfqd->bfq_wr_coeff = 30;
-+	bfqd->bfq_wr_rt_max_time = msecs_to_jiffies(300);
-+	bfqd->bfq_wr_max_time = 0;
-+	bfqd->bfq_wr_min_idle_time = msecs_to_jiffies(2000);
-+	bfqd->bfq_wr_min_inter_arr_async = msecs_to_jiffies(500);
-+	bfqd->bfq_wr_max_softrt_rate = 7000; /*
-+					      * Approximate rate required
-+					      * to playback or record a
-+					      * high-definition compressed
-+					      * video.
-+					      */
-+	bfqd->wr_busy_queues = 0;
-+
-+	/*
-+	 * Begin by assuming, optimistically, that the device is a
-+	 * high-speed one, and that its peak rate is equal to 2/3 of
-+	 * the highest reference rate.
-+	 */
-+	bfqd->RT_prod = R_fast[blk_queue_nonrot(bfqd->queue)] *
-+			T_fast[blk_queue_nonrot(bfqd->queue)];
-+	bfqd->peak_rate = R_fast[blk_queue_nonrot(bfqd->queue)] * 2 / 3;
-+	bfqd->device_speed = BFQ_BFQD_FAST;
-+
-+	return 0;
-+
-+out_free:
-+	kfree(bfqd);
-+	kobject_put(&eq->kobj);
-+	return -ENOMEM;
-+}
-+
-+static void bfq_slab_kill(void)
-+{
-+	kmem_cache_destroy(bfq_pool);
-+}
-+
-+static int __init bfq_slab_setup(void)
-+{
-+	bfq_pool = KMEM_CACHE(bfq_queue, 0);
-+	if (!bfq_pool)
-+		return -ENOMEM;
-+	return 0;
-+}
-+
-+static ssize_t bfq_var_show(unsigned int var, char *page)
-+{
-+	return sprintf(page, "%u\n", var);
-+}
-+
-+static ssize_t bfq_var_store(unsigned long *var, const char *page,
-+			     size_t count)
-+{
-+	unsigned long new_val;
-+	int ret = kstrtoul(page, 10, &new_val);
-+
-+	if (ret == 0)
-+		*var = new_val;
-+
-+	return count;
-+}
-+
-+static ssize_t bfq_wr_max_time_show(struct elevator_queue *e, char *page)
-+{
-+	struct bfq_data *bfqd = e->elevator_data;
-+
-+	return sprintf(page, "%d\n", bfqd->bfq_wr_max_time > 0 ?
-+		       jiffies_to_msecs(bfqd->bfq_wr_max_time) :
-+		       jiffies_to_msecs(bfq_wr_duration(bfqd)));
-+}
-+
-+static ssize_t bfq_weights_show(struct elevator_queue *e, char *page)
-+{
-+	struct bfq_queue *bfqq;
-+	struct bfq_data *bfqd = e->elevator_data;
-+	ssize_t num_char = 0;
-+
-+	num_char += sprintf(page + num_char, "Tot reqs queued %d\n\n",
-+			    bfqd->queued);
-+
-+	spin_lock_irq(bfqd->queue->queue_lock);
-+
-+	num_char += sprintf(page + num_char, "Active:\n");
-+	list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list) {
-+		num_char += sprintf(page + num_char,
-+				    "pid%d: weight %hu, nr_queued %d %d, ",
-+				    bfqq->pid,
-+				    bfqq->entity.weight,
-+				    bfqq->queued[0],
-+				    bfqq->queued[1]);
-+		num_char += sprintf(page + num_char,
-+				    "dur %d/%u\n",
-+				    jiffies_to_msecs(
-+					    jiffies -
-+					    bfqq->last_wr_start_finish),
-+				    jiffies_to_msecs(bfqq->wr_cur_max_time));
-+	}
-+
-+	num_char += sprintf(page + num_char, "Idle:\n");
-+	list_for_each_entry(bfqq, &bfqd->idle_list, bfqq_list) {
-+		num_char += sprintf(page + num_char,
-+				    "pid%d: weight %hu, dur %d/%u\n",
-+				    bfqq->pid,
-+				    bfqq->entity.weight,
-+				    jiffies_to_msecs(jiffies -
-+						     bfqq->last_wr_start_finish),
-+				    jiffies_to_msecs(bfqq->wr_cur_max_time));
-+	}
-+
-+	spin_unlock_irq(bfqd->queue->queue_lock);
-+
-+	return num_char;
-+}
-+
-+#define SHOW_FUNCTION(__FUNC, __VAR, __CONV)				\
-+static ssize_t __FUNC(struct elevator_queue *e, char *page)		\
-+{									\
-+	struct bfq_data *bfqd = e->elevator_data;			\
-+	u64 __data = __VAR;						\
-+	if (__CONV == 1)						\
-+		__data = jiffies_to_msecs(__data);			\
-+	else if (__CONV == 2)						\
-+		__data = div_u64(__data, NSEC_PER_MSEC);		\
-+	return bfq_var_show(__data, (page));				\
-+}
-+SHOW_FUNCTION(bfq_fifo_expire_sync_show, bfqd->bfq_fifo_expire[1], 2);
-+SHOW_FUNCTION(bfq_fifo_expire_async_show, bfqd->bfq_fifo_expire[0], 2);
-+SHOW_FUNCTION(bfq_back_seek_max_show, bfqd->bfq_back_max, 0);
-+SHOW_FUNCTION(bfq_back_seek_penalty_show, bfqd->bfq_back_penalty, 0);
-+SHOW_FUNCTION(bfq_slice_idle_show, bfqd->bfq_slice_idle, 2);
-+SHOW_FUNCTION(bfq_max_budget_show, bfqd->bfq_user_max_budget, 0);
-+SHOW_FUNCTION(bfq_timeout_sync_show, bfqd->bfq_timeout, 1);
-+SHOW_FUNCTION(bfq_strict_guarantees_show, bfqd->strict_guarantees, 0);
-+SHOW_FUNCTION(bfq_low_latency_show, bfqd->low_latency, 0);
-+SHOW_FUNCTION(bfq_wr_coeff_show, bfqd->bfq_wr_coeff, 0);
-+SHOW_FUNCTION(bfq_wr_rt_max_time_show, bfqd->bfq_wr_rt_max_time, 1);
-+SHOW_FUNCTION(bfq_wr_min_idle_time_show, bfqd->bfq_wr_min_idle_time, 1);
-+SHOW_FUNCTION(bfq_wr_min_inter_arr_async_show, bfqd->bfq_wr_min_inter_arr_async,
-+	1);
-+SHOW_FUNCTION(bfq_wr_max_softrt_rate_show, bfqd->bfq_wr_max_softrt_rate, 0);
-+#undef SHOW_FUNCTION
-+
-+#define USEC_SHOW_FUNCTION(__FUNC, __VAR)				\
-+static ssize_t __FUNC(struct elevator_queue *e, char *page)		\
-+{									\
-+	struct bfq_data *bfqd = e->elevator_data;			\
-+	u64 __data = __VAR;						\
-+	__data = div_u64(__data, NSEC_PER_USEC);			\
-+	return bfq_var_show(__data, (page));				\
-+}
-+USEC_SHOW_FUNCTION(bfq_slice_idle_us_show, bfqd->bfq_slice_idle);
-+#undef USEC_SHOW_FUNCTION
-+
-+#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV)			\
-+static ssize_t								\
-+__FUNC(struct elevator_queue *e, const char *page, size_t count)	\
-+{									\
-+	struct bfq_data *bfqd = e->elevator_data;			\
-+	unsigned long uninitialized_var(__data);			\
-+	int ret = bfq_var_store(&__data, (page), count);		\
-+	if (__data < (MIN))						\
-+		__data = (MIN);						\
-+	else if (__data > (MAX))					\
-+		__data = (MAX);						\
-+	if (__CONV == 1)						\
-+		*(__PTR) = msecs_to_jiffies(__data);			\
-+	else if (__CONV == 2)						\
-+		*(__PTR) = (u64)__data * NSEC_PER_MSEC;			\
-+	else								\
-+		*(__PTR) = __data;					\
-+	return ret;							\
-+}
-+STORE_FUNCTION(bfq_fifo_expire_sync_store, &bfqd->bfq_fifo_expire[1], 1,
-+		INT_MAX, 2);
-+STORE_FUNCTION(bfq_fifo_expire_async_store, &bfqd->bfq_fifo_expire[0], 1,
-+		INT_MAX, 2);
-+STORE_FUNCTION(bfq_back_seek_max_store, &bfqd->bfq_back_max, 0, INT_MAX, 0);
-+STORE_FUNCTION(bfq_back_seek_penalty_store, &bfqd->bfq_back_penalty, 1,
-+		INT_MAX, 0);
-+STORE_FUNCTION(bfq_slice_idle_store, &bfqd->bfq_slice_idle, 0, INT_MAX, 2);
-+STORE_FUNCTION(bfq_wr_coeff_store, &bfqd->bfq_wr_coeff, 1, INT_MAX, 0);
-+STORE_FUNCTION(bfq_wr_max_time_store, &bfqd->bfq_wr_max_time, 0, INT_MAX, 1);
-+STORE_FUNCTION(bfq_wr_rt_max_time_store, &bfqd->bfq_wr_rt_max_time, 0, INT_MAX,
-+		1);
-+STORE_FUNCTION(bfq_wr_min_idle_time_store, &bfqd->bfq_wr_min_idle_time, 0,
-+		INT_MAX, 1);
-+STORE_FUNCTION(bfq_wr_min_inter_arr_async_store,
-+		&bfqd->bfq_wr_min_inter_arr_async, 0, INT_MAX, 1);
-+STORE_FUNCTION(bfq_wr_max_softrt_rate_store, &bfqd->bfq_wr_max_softrt_rate, 0,
-+		INT_MAX, 0);
-+#undef STORE_FUNCTION
-+
-+#define USEC_STORE_FUNCTION(__FUNC, __PTR, MIN, MAX)			\
-+static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count)\
-+{									\
-+	struct bfq_data *bfqd = e->elevator_data;			\
-+	unsigned long uninitialized_var(__data);			\
-+	int ret = bfq_var_store(&__data, (page), count);		\
-+	if (__data < (MIN))						\
-+		__data = (MIN);						\
-+	else if (__data > (MAX))					\
-+		__data = (MAX);						\
-+	*(__PTR) = (u64)__data * NSEC_PER_USEC;				\
-+	return ret;							\
-+}
-+USEC_STORE_FUNCTION(bfq_slice_idle_us_store, &bfqd->bfq_slice_idle, 0,
-+		    UINT_MAX);
-+#undef USEC_STORE_FUNCTION
-+
-+/* do nothing for the moment */
-+static ssize_t bfq_weights_store(struct elevator_queue *e,
-+				    const char *page, size_t count)
-+{
-+	return count;
-+}
-+
-+static ssize_t bfq_max_budget_store(struct elevator_queue *e,
-+				    const char *page, size_t count)
-+{
-+	struct bfq_data *bfqd = e->elevator_data;
-+	unsigned long uninitialized_var(__data);
-+	int ret = bfq_var_store(&__data, (page), count);
-+
-+	if (__data == 0)
-+		bfqd->bfq_max_budget = bfq_calc_max_budget(bfqd);
-+	else {
-+		if (__data > INT_MAX)
-+			__data = INT_MAX;
-+		bfqd->bfq_max_budget = __data;
-+	}
-+
-+	bfqd->bfq_user_max_budget = __data;
-+
-+	return ret;
-+}
-+
-+/*
-+ * Leaving this name to preserve name compatibility with cfq
-+ * parameters, but this timeout is used for both sync and async.
-+ */
-+static ssize_t bfq_timeout_sync_store(struct elevator_queue *e,
-+				      const char *page, size_t count)
-+{
-+	struct bfq_data *bfqd = e->elevator_data;
-+	unsigned long uninitialized_var(__data);
-+	int ret = bfq_var_store(&__data, (page), count);
-+
-+	if (__data < 1)
-+		__data = 1;
-+	else if (__data > INT_MAX)
-+		__data = INT_MAX;
-+
-+	bfqd->bfq_timeout = msecs_to_jiffies(__data);
-+	if (bfqd->bfq_user_max_budget == 0)
-+		bfqd->bfq_max_budget = bfq_calc_max_budget(bfqd);
-+
-+	return ret;
-+}
-+
-+static ssize_t bfq_strict_guarantees_store(struct elevator_queue *e,
-+				     const char *page, size_t count)
-+{
-+	struct bfq_data *bfqd = e->elevator_data;
-+	unsigned long uninitialized_var(__data);
-+	int ret = bfq_var_store(&__data, (page), count);
-+
-+	if (__data > 1)
-+		__data = 1;
-+	if (!bfqd->strict_guarantees && __data == 1
-+	    && bfqd->bfq_slice_idle < 8 * NSEC_PER_MSEC)
-+		bfqd->bfq_slice_idle = 8 * NSEC_PER_MSEC;
-+
-+	bfqd->strict_guarantees = __data;
-+
-+	return ret;
-+}
-+
-+static ssize_t bfq_low_latency_store(struct elevator_queue *e,
-+				     const char *page, size_t count)
-+{
-+	struct bfq_data *bfqd = e->elevator_data;
-+	unsigned long uninitialized_var(__data);
-+	int ret = bfq_var_store(&__data, (page), count);
-+
-+	if (__data > 1)
-+		__data = 1;
-+	if (__data == 0 && bfqd->low_latency != 0)
-+		bfq_end_wr(bfqd);
-+	bfqd->low_latency = __data;
-+
-+	return ret;
-+}
-+
-+#define BFQ_ATTR(name) \
-+	__ATTR(name, S_IRUGO|S_IWUSR, bfq_##name##_show, bfq_##name##_store)
-+
-+static struct elv_fs_entry bfq_attrs[] = {
-+	BFQ_ATTR(fifo_expire_sync),
-+	BFQ_ATTR(fifo_expire_async),
-+	BFQ_ATTR(back_seek_max),
-+	BFQ_ATTR(back_seek_penalty),
-+	BFQ_ATTR(slice_idle),
-+	BFQ_ATTR(slice_idle_us),
-+	BFQ_ATTR(max_budget),
-+	BFQ_ATTR(timeout_sync),
-+	BFQ_ATTR(strict_guarantees),
-+	BFQ_ATTR(low_latency),
-+	BFQ_ATTR(wr_coeff),
-+	BFQ_ATTR(wr_max_time),
-+	BFQ_ATTR(wr_rt_max_time),
-+	BFQ_ATTR(wr_min_idle_time),
-+	BFQ_ATTR(wr_min_inter_arr_async),
-+	BFQ_ATTR(wr_max_softrt_rate),
-+	BFQ_ATTR(weights),
-+	__ATTR_NULL
-+};
-+
-+static struct elevator_type iosched_bfq = {
-+	.ops.sq = {
-+		.elevator_merge_fn =		bfq_merge,
-+		.elevator_merged_fn =		bfq_merged_request,
-+		.elevator_merge_req_fn =	bfq_merged_requests,
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+		.elevator_bio_merged_fn =	bfq_bio_merged,
-+#endif
-+		.elevator_allow_bio_merge_fn =	bfq_allow_bio_merge,
-+		.elevator_allow_rq_merge_fn =	bfq_allow_rq_merge,
-+		.elevator_dispatch_fn =		bfq_dispatch_requests,
-+		.elevator_add_req_fn =		bfq_insert_request,
-+		.elevator_activate_req_fn =	bfq_activate_request,
-+		.elevator_deactivate_req_fn =	bfq_deactivate_request,
-+		.elevator_completed_req_fn =	bfq_completed_request,
-+		.elevator_former_req_fn =	elv_rb_former_request,
-+		.elevator_latter_req_fn =	elv_rb_latter_request,
-+		.elevator_init_icq_fn =		bfq_init_icq,
-+		.elevator_exit_icq_fn =		bfq_exit_icq,
-+		.elevator_set_req_fn =		bfq_set_request,
-+		.elevator_put_req_fn =		bfq_put_request,
-+		.elevator_may_queue_fn =	bfq_may_queue,
-+		.elevator_init_fn =		bfq_init_queue,
-+		.elevator_exit_fn =		bfq_exit_queue,
-+	},
-+	.icq_size =		sizeof(struct bfq_io_cq),
-+	.icq_align =		__alignof__(struct bfq_io_cq),
-+	.elevator_attrs =	bfq_attrs,
-+	.elevator_name =	"bfq-sq",
-+	.elevator_owner =	THIS_MODULE,
-+};
-+
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+static struct blkcg_policy blkcg_policy_bfq = {
-+	.dfl_cftypes		= bfq_blkg_files,
-+	.legacy_cftypes		= bfq_blkcg_legacy_files,
-+
-+	.cpd_alloc_fn		= bfq_cpd_alloc,
-+	.cpd_init_fn		= bfq_cpd_init,
-+	.cpd_bind_fn	        = bfq_cpd_init,
-+	.cpd_free_fn		= bfq_cpd_free,
-+
-+	.pd_alloc_fn		= bfq_pd_alloc,
-+	.pd_init_fn		= bfq_pd_init,
-+	.pd_offline_fn		= bfq_pd_offline,
-+	.pd_free_fn		= bfq_pd_free,
-+	.pd_reset_stats_fn	= bfq_pd_reset_stats,
-+};
-+#endif
-+
-+static int __init bfq_init(void)
-+{
-+	int ret;
-+	char msg[60] = "BFQ I/O-scheduler: v8r12";
-+
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	ret = blkcg_policy_register(&blkcg_policy_bfq);
-+	if (ret)
-+		return ret;
-+#endif
-+
-+	ret = -ENOMEM;
-+	if (bfq_slab_setup())
-+		goto err_pol_unreg;
-+
-+	/*
-+	 * Times to load large popular applications for the typical
-+	 * systems installed on the reference devices (see the
-+	 * comments before the definitions of the next two
-+	 * arrays). Actually, we use slightly slower values, as the
-+	 * estimated peak rate tends to be smaller than the actual
-+	 * peak rate.  The reason for this last fact is that estimates
-+	 * are computed over much shorter time intervals than the long
-+	 * intervals typically used for benchmarking. Why? First, to
-+	 * adapt more quickly to variations. Second, because an I/O
-+	 * scheduler cannot rely on a peak-rate-evaluation workload to
-+	 * be run for a long time.
-+	 */
-+	T_slow[0] = msecs_to_jiffies(3500); /* actually 4 sec */
-+	T_slow[1] = msecs_to_jiffies(6000); /* actually 6.5 sec */
-+	T_fast[0] = msecs_to_jiffies(7000); /* actually 8 sec */
-+	T_fast[1] = msecs_to_jiffies(2500); /* actually 3 sec */
-+
-+	/*
-+	 * Thresholds that determine the switch between speed classes
-+	 * (see the comments before the definition of the array
-+	 * device_speed_thresh). These thresholds are biased towards
-+	 * transitions to the fast class. This is safer than the
-+	 * opposite bias. In fact, a wrong transition to the slow
-+	 * class results in short weight-raising periods, because the
-+	 * speed of the device then tends to be higher that the
-+	 * reference peak rate. On the opposite end, a wrong
-+	 * transition to the fast class tends to increase
-+	 * weight-raising periods, because of the opposite reason.
-+	 */
-+	device_speed_thresh[0] = (4 * R_slow[0]) / 3;
-+	device_speed_thresh[1] = (4 * R_slow[1]) / 3;
-+
-+	ret = elv_register(&iosched_bfq);
-+	if (ret)
-+		goto err_pol_unreg;
-+
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	strcat(msg, " (with cgroups support)");
-+#endif
-+	pr_info("%s", msg);
-+
-+	return 0;
-+
-+err_pol_unreg:
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	blkcg_policy_unregister(&blkcg_policy_bfq);
-+#endif
-+	return ret;
-+}
-+
-+static void __exit bfq_exit(void)
-+{
-+	elv_unregister(&iosched_bfq);
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	blkcg_policy_unregister(&blkcg_policy_bfq);
-+#endif
-+	bfq_slab_kill();
-+}
-+
-+module_init(bfq_init);
-+module_exit(bfq_exit);
-+
-+MODULE_AUTHOR("Arianna Avanzini, Fabio Checconi, Paolo Valente");
-+MODULE_LICENSE("GPL");
-diff --git a/block/bfq.h b/block/bfq.h
-new file mode 100644
-index 000000000000..f5751ea59d98
---- /dev/null
-+++ b/block/bfq.h
-@@ -0,0 +1,948 @@
-+/*
-+ * BFQ v8r12 for 4.11.0: data structures and common functions prototypes.
-+ *
-+ * Based on ideas and code from CFQ:
-+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
-+ *
-+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
-+ *		      Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2017 Paolo Valente <paolo.valente@linaro.org>
-+ */
-+
-+#ifndef _BFQ_H
-+#define _BFQ_H
-+
-+#include <linux/blktrace_api.h>
-+#include <linux/hrtimer.h>
-+#include <linux/blk-cgroup.h>
-+
-+#define BFQ_IOPRIO_CLASSES	3
-+#define BFQ_CL_IDLE_TIMEOUT	(HZ/5)
-+
-+#define BFQ_MIN_WEIGHT			1
-+#define BFQ_MAX_WEIGHT			1000
-+#define BFQ_WEIGHT_CONVERSION_COEFF	10
-+
-+#define BFQ_DEFAULT_QUEUE_IOPRIO	4
-+
-+#define BFQ_WEIGHT_LEGACY_DFL	100
-+#define BFQ_DEFAULT_GRP_IOPRIO	0
-+#define BFQ_DEFAULT_GRP_CLASS	IOPRIO_CLASS_BE
-+
-+/*
-+ * Soft real-time applications are extremely more latency sensitive
-+ * than interactive ones. Over-raise the weight of the former to
-+ * privilege them against the latter.
-+ */
-+#define BFQ_SOFTRT_WEIGHT_FACTOR	100
-+
-+struct bfq_entity;
-+
-+/**
-+ * struct bfq_service_tree - per ioprio_class service tree.
-+ *
-+ * Each service tree represents a B-WF2Q+ scheduler on its own.  Each
-+ * ioprio_class has its own independent scheduler, and so its own
-+ * bfq_service_tree.  All the fields are protected by the queue lock
-+ * of the containing bfqd.
-+ */
-+struct bfq_service_tree {
-+	/* tree for active entities (i.e., those backlogged) */
-+	struct rb_root active;
-+	/* tree for idle entities (i.e., not backlogged, with V <= F_i)*/
-+	struct rb_root idle;
-+
-+	struct bfq_entity *first_idle;	/* idle entity with minimum F_i */
-+	struct bfq_entity *last_idle;	/* idle entity with maximum F_i */
-+
-+	u64 vtime; /* scheduler virtual time */
-+	/* scheduler weight sum; active and idle entities contribute to it */
-+	unsigned long wsum;
-+};
-+
-+/**
-+ * struct bfq_sched_data - multi-class scheduler.
-+ *
-+ * bfq_sched_data is the basic scheduler queue.  It supports three
-+ * ioprio_classes, and can be used either as a toplevel queue or as an
-+ * intermediate queue on a hierarchical setup.  @next_in_service
-+ * points to the active entity of the sched_data service trees that
-+ * will be scheduled next. It is used to reduce the number of steps
-+ * needed for each hierarchical-schedule update.
-+ *
-+ * The supported ioprio_classes are the same as in CFQ, in descending
-+ * priority order, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE.
-+ * Requests from higher priority queues are served before all the
-+ * requests from lower priority queues; among requests of the same
-+ * queue requests are served according to B-WF2Q+.
-+ * All the fields are protected by the queue lock of the containing bfqd.
-+ */
-+struct bfq_sched_data {
-+	struct bfq_entity *in_service_entity;  /* entity in service */
-+	/* head-of-the-line entity in the scheduler (see comments above) */
-+	struct bfq_entity *next_in_service;
-+	/* array of service trees, one per ioprio_class */
-+	struct bfq_service_tree service_tree[BFQ_IOPRIO_CLASSES];
-+	/* last time CLASS_IDLE was served */
-+	unsigned long bfq_class_idle_last_service;
-+
-+};
-+
-+/**
-+ * struct bfq_weight_counter - counter of the number of all active entities
-+ *                             with a given weight.
-+ */
-+struct bfq_weight_counter {
-+	unsigned int weight; /* weight of the entities this counter refers to */
-+	unsigned int num_active; /* nr of active entities with this weight */
-+	/*
-+	 * Weights tree member (see bfq_data's @queue_weights_tree and
-+	 * @group_weights_tree)
-+	 */
-+	struct rb_node weights_node;
-+};
-+
-+/**
-+ * struct bfq_entity - schedulable entity.
-+ *
-+ * A bfq_entity is used to represent either a bfq_queue (leaf node in the
-+ * cgroup hierarchy) or a bfq_group into the upper level scheduler.  Each
-+ * entity belongs to the sched_data of the parent group in the cgroup
-+ * hierarchy.  Non-leaf entities have also their own sched_data, stored
-+ * in @my_sched_data.
-+ *
-+ * Each entity stores independently its priority values; this would
-+ * allow different weights on different devices, but this
-+ * functionality is not exported to userspace by now.  Priorities and
-+ * weights are updated lazily, first storing the new values into the
-+ * new_* fields, then setting the @prio_changed flag.  As soon as
-+ * there is a transition in the entity state that allows the priority
-+ * update to take place the effective and the requested priority
-+ * values are synchronized.
-+ *
-+ * Unless cgroups are used, the weight value is calculated from the
-+ * ioprio to export the same interface as CFQ.  When dealing with
-+ * ``well-behaved'' queues (i.e., queues that do not spend too much
-+ * time to consume their budget and have true sequential behavior, and
-+ * when there are no external factors breaking anticipation) the
-+ * relative weights at each level of the cgroups hierarchy should be
-+ * guaranteed.  All the fields are protected by the queue lock of the
-+ * containing bfqd.
-+ */
-+struct bfq_entity {
-+	struct rb_node rb_node; /* service_tree member */
-+	/* pointer to the weight counter associated with this entity */
-+	struct bfq_weight_counter *weight_counter;
-+
-+	/*
-+	 * Flag, true if the entity is on a tree (either the active or
-+	 * the idle one of its service_tree) or is in service.
-+	 */
-+	bool on_st;
-+
-+	u64 finish; /* B-WF2Q+ finish timestamp (aka F_i) */
-+	u64 start;  /* B-WF2Q+ start timestamp (aka S_i) */
-+
-+	/* tree the entity is enqueued into; %NULL if not on a tree */
-+	struct rb_root *tree;
-+
-+	/*
-+	 * minimum start time of the (active) subtree rooted at this
-+	 * entity; used for O(log N) lookups into active trees
-+	 */
-+	u64 min_start;
-+
-+	/* amount of service received during the last service slot */
-+	int service;
-+
-+	/* budget, used also to calculate F_i: F_i = S_i + @budget / @weight */
-+	int budget;
-+
-+	unsigned int weight;	 /* weight of the queue */
-+	unsigned int new_weight; /* next weight if a change is in progress */
-+
-+	/* original weight, used to implement weight boosting */
-+	unsigned int orig_weight;
-+
-+	/* parent entity, for hierarchical scheduling */
-+	struct bfq_entity *parent;
-+
-+	/*
-+	 * For non-leaf nodes in the hierarchy, the associated
-+	 * scheduler queue, %NULL on leaf nodes.
-+	 */
-+	struct bfq_sched_data *my_sched_data;
-+	/* the scheduler queue this entity belongs to */
-+	struct bfq_sched_data *sched_data;
-+
-+	/* flag, set to request a weight, ioprio or ioprio_class change  */
-+	int prio_changed;
-+};
-+
-+struct bfq_group;
-+
-+/**
-+ * struct bfq_queue - leaf schedulable entity.
-+ *
-+ * A bfq_queue is a leaf request queue; it can be associated with an
-+ * io_context or more, if it  is  async or shared  between  cooperating
-+ * processes. @cgroup holds a reference to the cgroup, to be sure that it
-+ * does not disappear while a bfqq still references it (mostly to avoid
-+ * races between request issuing and task migration followed by cgroup
-+ * destruction).
-+ * All the fields are protected by the queue lock of the containing bfqd.
-+ */
-+struct bfq_queue {
-+	/* reference counter */
-+	int ref;
-+	/* parent bfq_data */
-+	struct bfq_data *bfqd;
-+
-+	/* current ioprio and ioprio class */
-+	unsigned short ioprio, ioprio_class;
-+	/* next ioprio and ioprio class if a change is in progress */
-+	unsigned short new_ioprio, new_ioprio_class;
-+
-+	/*
-+	 * Shared bfq_queue if queue is cooperating with one or more
-+	 * other queues.
-+	 */
-+	struct bfq_queue *new_bfqq;
-+	/* request-position tree member (see bfq_group's @rq_pos_tree) */
-+	struct rb_node pos_node;
-+	/* request-position tree root (see bfq_group's @rq_pos_tree) */
-+	struct rb_root *pos_root;
-+
-+	/* sorted list of pending requests */
-+	struct rb_root sort_list;
-+	/* if fifo isn't expired, next request to serve */
-+	struct request *next_rq;
-+	/* number of sync and async requests queued */
-+	int queued[2];
-+	/* number of sync and async requests currently allocated */
-+	int allocated[2];
-+	/* number of pending metadata requests */
-+	int meta_pending;
-+	/* fifo list of requests in sort_list */
-+	struct list_head fifo;
-+
-+	/* entity representing this queue in the scheduler */
-+	struct bfq_entity entity;
-+
-+	/* maximum budget allowed from the feedback mechanism */
-+	int max_budget;
-+	/* budget expiration (in jiffies) */
-+	unsigned long budget_timeout;
-+
-+	/* number of requests on the dispatch list or inside driver */
-+	int dispatched;
-+
-+	unsigned int flags; /* status flags.*/
-+
-+	/* node for active/idle bfqq list inside parent bfqd */
-+	struct list_head bfqq_list;
-+
-+	/* bit vector: a 1 for each seeky requests in history */
-+	u32 seek_history;
-+
-+	/* node for the device's burst list */
-+	struct hlist_node burst_list_node;
-+
-+	/* position of the last request enqueued */
-+	sector_t last_request_pos;
-+
-+	/* Number of consecutive pairs of request completion and
-+	 * arrival, such that the queue becomes idle after the
-+	 * completion, but the next request arrives within an idle
-+	 * time slice; used only if the queue's IO_bound flag has been
-+	 * cleared.
-+	 */
-+	unsigned int requests_within_timer;
-+
-+	/* pid of the process owning the queue, used for logging purposes */
-+	pid_t pid;
-+
-+	/*
-+	 * Pointer to the bfq_io_cq owning the bfq_queue, set to %NULL
-+	 * if the queue is shared.
-+	 */
-+	struct bfq_io_cq *bic;
-+
-+	/* current maximum weight-raising time for this queue */
-+	unsigned long wr_cur_max_time;
-+	/*
-+	 * Minimum time instant such that, only if a new request is
-+	 * enqueued after this time instant in an idle @bfq_queue with
-+	 * no outstanding requests, then the task associated with the
-+	 * queue it is deemed as soft real-time (see the comments on
-+	 * the function bfq_bfqq_softrt_next_start())
-+	 */
-+	unsigned long soft_rt_next_start;
-+	/*
-+	 * Start time of the current weight-raising period if
-+	 * the @bfq-queue is being weight-raised, otherwise
-+	 * finish time of the last weight-raising period.
-+	 */
-+	unsigned long last_wr_start_finish;
-+	/* factor by which the weight of this queue is multiplied */
-+	unsigned int wr_coeff;
-+	/*
-+	 * Time of the last transition of the @bfq_queue from idle to
-+	 * backlogged.
-+	 */
-+	unsigned long last_idle_bklogged;
-+	/*
-+	 * Cumulative service received from the @bfq_queue since the
-+	 * last transition from idle to backlogged.
-+	 */
-+	unsigned long service_from_backlogged;
-+	/*
-+	 * Value of wr start time when switching to soft rt
-+	 */
-+	unsigned long wr_start_at_switch_to_srt;
-+
-+	unsigned long split_time; /* time of last split */
-+};
-+
-+/**
-+ * struct bfq_ttime - per process thinktime stats.
-+ */
-+struct bfq_ttime {
-+	u64 last_end_request; /* completion time of last request */
-+
-+	u64 ttime_total; /* total process thinktime */
-+	unsigned long ttime_samples; /* number of thinktime samples */
-+	u64 ttime_mean; /* average process thinktime */
-+
-+};
-+
-+/**
-+ * struct bfq_io_cq - per (request_queue, io_context) structure.
-+ */
-+struct bfq_io_cq {
-+	/* associated io_cq structure */
-+	struct io_cq icq; /* must be the first member */
-+	/* array of two process queues, the sync and the async */
-+	struct bfq_queue *bfqq[2];
-+	/* associated @bfq_ttime struct */
-+	struct bfq_ttime ttime;
-+	/* per (request_queue, blkcg) ioprio */
-+	int ioprio;
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	uint64_t blkcg_serial_nr; /* the current blkcg serial */
-+#endif
-+
-+	/*
-+	 * Snapshot of the idle window before merging; taken to
-+	 * remember this value while the queue is merged, so as to be
-+	 * able to restore it in case of split.
-+	 */
-+	bool saved_idle_window;
-+	/*
-+	 * Same purpose as the previous two fields for the I/O bound
-+	 * classification of a queue.
-+	 */
-+	bool saved_IO_bound;
-+
-+	/*
-+	 * Same purpose as the previous fields for the value of the
-+	 * field keeping the queue's belonging to a large burst
-+	 */
-+	bool saved_in_large_burst;
-+	/*
-+	 * True if the queue belonged to a burst list before its merge
-+	 * with another cooperating queue.
-+	 */
-+	bool was_in_burst_list;
-+
-+	/*
-+	 * Similar to previous fields: save wr information.
-+	 */
-+	unsigned long saved_wr_coeff;
-+	unsigned long saved_last_wr_start_finish;
-+	unsigned long saved_wr_start_at_switch_to_srt;
-+	unsigned int saved_wr_cur_max_time;
-+};
-+
-+enum bfq_device_speed {
-+	BFQ_BFQD_FAST,
-+	BFQ_BFQD_SLOW,
-+};
-+
-+/**
-+ * struct bfq_data - per-device data structure.
-+ *
-+ * All the fields are protected by the @queue lock.
-+ */
-+struct bfq_data {
-+	/* request queue for the device */
-+	struct request_queue *queue;
-+
-+	/* root bfq_group for the device */
-+	struct bfq_group *root_group;
-+
-+	/*
-+	 * rbtree of weight counters of @bfq_queues, sorted by
-+	 * weight. Used to keep track of whether all @bfq_queues have
-+	 * the same weight. The tree contains one counter for each
-+	 * distinct weight associated to some active and not
-+	 * weight-raised @bfq_queue (see the comments to the functions
-+	 * bfq_weights_tree_[add|remove] for further details).
-+	 */
-+	struct rb_root queue_weights_tree;
-+	/*
-+	 * rbtree of non-queue @bfq_entity weight counters, sorted by
-+	 * weight. Used to keep track of whether all @bfq_groups have
-+	 * the same weight. The tree contains one counter for each
-+	 * distinct weight associated to some active @bfq_group (see
-+	 * the comments to the functions bfq_weights_tree_[add|remove]
-+	 * for further details).
-+	 */
-+	struct rb_root group_weights_tree;
-+
-+	/*
-+	 * Number of bfq_queues containing requests (including the
-+	 * queue in service, even if it is idling).
-+	 */
-+	int busy_queues;
-+	/* number of weight-raised busy @bfq_queues */
-+	int wr_busy_queues;
-+	/* number of queued requests */
-+	int queued;
-+	/* number of requests dispatched and waiting for completion */
-+	int rq_in_driver;
-+
-+	/*
-+	 * Maximum number of requests in driver in the last
-+	 * @hw_tag_samples completed requests.
-+	 */
-+	int max_rq_in_driver;
-+	/* number of samples used to calculate hw_tag */
-+	int hw_tag_samples;
-+	/* flag set to one if the driver is showing a queueing behavior */
-+	int hw_tag;
-+
-+	/* number of budgets assigned */
-+	int budgets_assigned;
-+
-+	/*
-+	 * Timer set when idling (waiting) for the next request from
-+	 * the queue in service.
-+	 */
-+	struct hrtimer idle_slice_timer;
-+	/* delayed work to restart dispatching on the request queue */
-+	struct work_struct unplug_work;
-+
-+	/* bfq_queue in service */
-+	struct bfq_queue *in_service_queue;
-+	/* bfq_io_cq (bic) associated with the @in_service_queue */
-+	struct bfq_io_cq *in_service_bic;
-+
-+	/* on-disk position of the last served request */
-+	sector_t last_position;
-+
-+	/* time of last request completion (ns) */
-+	u64 last_completion;
-+
-+	/* time of first rq dispatch in current observation interval (ns) */
-+	u64 first_dispatch;
-+	/* time of last rq dispatch in current observation interval (ns) */
-+	u64 last_dispatch;
-+
-+	/* beginning of the last budget */
-+	ktime_t last_budget_start;
-+	/* beginning of the last idle slice */
-+	ktime_t last_idling_start;
-+
-+	/* number of samples in current observation interval */
-+	int peak_rate_samples;
-+	/* num of samples of seq dispatches in current observation interval */
-+	u32 sequential_samples;
-+	/* total num of sectors transferred in current observation interval */
-+	u64 tot_sectors_dispatched;
-+	/* max rq size seen during current observation interval (sectors) */
-+	u32 last_rq_max_size;
-+	/* time elapsed from first dispatch in current observ. interval (us) */
-+	u64 delta_from_first;
-+	/* current estimate of device peak rate */
-+	u32 peak_rate;
-+
-+	/* maximum budget allotted to a bfq_queue before rescheduling */
-+	int bfq_max_budget;
-+
-+	/* list of all the bfq_queues active on the device */
-+	struct list_head active_list;
-+	/* list of all the bfq_queues idle on the device */
-+	struct list_head idle_list;
-+
-+	/*
-+	 * Timeout for async/sync requests; when it fires, requests
-+	 * are served in fifo order.
-+	 */
-+	u64 bfq_fifo_expire[2];
-+	/* weight of backward seeks wrt forward ones */
-+	unsigned int bfq_back_penalty;
-+	/* maximum allowed backward seek */
-+	unsigned int bfq_back_max;
-+	/* maximum idling time */
-+	u32 bfq_slice_idle;
-+
-+	/* user-configured max budget value (0 for auto-tuning) */
-+	int bfq_user_max_budget;
-+	/*
-+	 * Timeout for bfq_queues to consume their budget; used to
-+	 * prevent seeky queues from imposing long latencies to
-+	 * sequential or quasi-sequential ones (this also implies that
-+	 * seeky queues cannot receive guarantees in the service
-+	 * domain; after a timeout they are charged for the time they
-+	 * have been in service, to preserve fairness among them, but
-+	 * without service-domain guarantees).
-+	 */
-+	unsigned int bfq_timeout;
-+
-+	/*
-+	 * Number of consecutive requests that must be issued within
-+	 * the idle time slice to set again idling to a queue which
-+	 * was marked as non-I/O-bound (see the definition of the
-+	 * IO_bound flag for further details).
-+	 */
-+	unsigned int bfq_requests_within_timer;
-+
-+	/*
-+	 * Force device idling whenever needed to provide accurate
-+	 * service guarantees, without caring about throughput
-+	 * issues. CAVEAT: this may even increase latencies, in case
-+	 * of useless idling for processes that did stop doing I/O.
-+	 */
-+	bool strict_guarantees;
-+
-+	/*
-+	 * Last time at which a queue entered the current burst of
-+	 * queues being activated shortly after each other; for more
-+	 * details about this and the following parameters related to
-+	 * a burst of activations, see the comments on the function
-+	 * bfq_handle_burst.
-+	 */
-+	unsigned long last_ins_in_burst;
-+	/*
-+	 * Reference time interval used to decide whether a queue has
-+	 * been activated shortly after @last_ins_in_burst.
-+	 */
-+	unsigned long bfq_burst_interval;
-+	/* number of queues in the current burst of queue activations */
-+	int burst_size;
-+
-+	/* common parent entity for the queues in the burst */
-+	struct bfq_entity *burst_parent_entity;
-+	/* Maximum burst size above which the current queue-activation
-+	 * burst is deemed as 'large'.
-+	 */
-+	unsigned long bfq_large_burst_thresh;
-+	/* true if a large queue-activation burst is in progress */
-+	bool large_burst;
-+	/*
-+	 * Head of the burst list (as for the above fields, more
-+	 * details in the comments on the function bfq_handle_burst).
-+	 */
-+	struct hlist_head burst_list;
-+
-+	/* if set to true, low-latency heuristics are enabled */
-+	bool low_latency;
-+	/*
-+	 * Maximum factor by which the weight of a weight-raised queue
-+	 * is multiplied.
-+	 */
-+	unsigned int bfq_wr_coeff;
-+	/* maximum duration of a weight-raising period (jiffies) */
-+	unsigned int bfq_wr_max_time;
-+
-+	/* Maximum weight-raising duration for soft real-time processes */
-+	unsigned int bfq_wr_rt_max_time;
-+	/*
-+	 * Minimum idle period after which weight-raising may be
-+	 * reactivated for a queue (in jiffies).
-+	 */
-+	unsigned int bfq_wr_min_idle_time;
-+	/*
-+	 * Minimum period between request arrivals after which
-+	 * weight-raising may be reactivated for an already busy async
-+	 * queue (in jiffies).
-+	 */
-+	unsigned long bfq_wr_min_inter_arr_async;
-+
-+	/* Max service-rate for a soft real-time queue, in sectors/sec */
-+	unsigned int bfq_wr_max_softrt_rate;
-+	/*
-+	 * Cached value of the product R*T, used for computing the
-+	 * maximum duration of weight raising automatically.
-+	 */
-+	u64 RT_prod;
-+	/* device-speed class for the low-latency heuristic */
-+	enum bfq_device_speed device_speed;
-+
-+	/* fallback dummy bfqq for extreme OOM conditions */
-+	struct bfq_queue oom_bfqq;
-+};
-+
-+enum bfqq_state_flags {
-+	BFQ_BFQQ_FLAG_just_created = 0,	/* queue just allocated */
-+	BFQ_BFQQ_FLAG_busy,		/* has requests or is in service */
-+	BFQ_BFQQ_FLAG_wait_request,	/* waiting for a request */
-+	BFQ_BFQQ_FLAG_non_blocking_wait_rq, /*
-+					     * waiting for a request
-+					     * without idling the device
-+					     */
-+	BFQ_BFQQ_FLAG_must_alloc,	/* must be allowed rq alloc */
-+	BFQ_BFQQ_FLAG_fifo_expire,	/* FIFO checked in this slice */
-+	BFQ_BFQQ_FLAG_idle_window,	/* slice idling enabled */
-+	BFQ_BFQQ_FLAG_sync,		/* synchronous queue */
-+	BFQ_BFQQ_FLAG_IO_bound,		/*
-+					 * bfqq has timed-out at least once
-+					 * having consumed at most 2/10 of
-+					 * its budget
-+					 */
-+	BFQ_BFQQ_FLAG_in_large_burst,	/*
-+					 * bfqq activated in a large burst,
-+					 * see comments to bfq_handle_burst.
-+					 */
-+	BFQ_BFQQ_FLAG_softrt_update,	/*
-+					 * may need softrt-next-start
-+					 * update
-+					 */
-+	BFQ_BFQQ_FLAG_coop,		/* bfqq is shared */
-+	BFQ_BFQQ_FLAG_split_coop	/* shared bfqq will be split */
-+};
-+
-+#define BFQ_BFQQ_FNS(name)						\
-+static void bfq_mark_bfqq_##name(struct bfq_queue *bfqq)		\
-+{									\
-+	(bfqq)->flags |= (1 << BFQ_BFQQ_FLAG_##name);			\
-+}									\
-+static void bfq_clear_bfqq_##name(struct bfq_queue *bfqq)		\
-+{									\
-+	(bfqq)->flags &= ~(1 << BFQ_BFQQ_FLAG_##name);			\
-+}									\
-+static int bfq_bfqq_##name(const struct bfq_queue *bfqq)		\
-+{									\
-+	return ((bfqq)->flags & (1 << BFQ_BFQQ_FLAG_##name)) != 0;	\
-+}
-+
-+BFQ_BFQQ_FNS(just_created);
-+BFQ_BFQQ_FNS(busy);
-+BFQ_BFQQ_FNS(wait_request);
-+BFQ_BFQQ_FNS(non_blocking_wait_rq);
-+BFQ_BFQQ_FNS(must_alloc);
-+BFQ_BFQQ_FNS(fifo_expire);
-+BFQ_BFQQ_FNS(idle_window);
-+BFQ_BFQQ_FNS(sync);
-+BFQ_BFQQ_FNS(IO_bound);
-+BFQ_BFQQ_FNS(in_large_burst);
-+BFQ_BFQQ_FNS(coop);
-+BFQ_BFQQ_FNS(split_coop);
-+BFQ_BFQQ_FNS(softrt_update);
-+#undef BFQ_BFQQ_FNS
-+
-+/* Logging facilities. */
-+#ifdef CONFIG_BFQ_REDIRECT_TO_CONSOLE
-+
-+static const char *checked_dev_name(const struct device *dev)
-+{
-+	static const char nodev[] = "nodev";
-+
-+	if (dev)
-+		return dev_name(dev);
-+
-+	return nodev;
-+}
-+
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+static struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
-+static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
-+
-+#define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	do {			\
-+	char __pbuf[128];						\
-+									\
-+	assert_spin_locked((bfqd)->queue->queue_lock);			\
-+	blkg_path(bfqg_to_blkg(bfqq_group(bfqq)), __pbuf, sizeof(__pbuf)); \
-+	pr_crit("%s bfq%d%c %s " fmt "\n", 				\
-+		checked_dev_name((bfqd)->queue->backing_dev_info->dev),	\
-+		(bfqq)->pid,						\
-+		bfq_bfqq_sync((bfqq)) ? 'S' : 'A',			\
-+		__pbuf, ##args);					\
-+} while (0)
-+
-+#define bfq_log_bfqg(bfqd, bfqg, fmt, args...)	do {			\
-+	char __pbuf[128];						\
-+									\
-+	blkg_path(bfqg_to_blkg(bfqg), __pbuf, sizeof(__pbuf));		\
-+	pr_crit("%s %s " fmt "\n",					\
-+	checked_dev_name((bfqd)->queue->backing_dev_info->dev),		\
-+	__pbuf, ##args);						\
-+} while (0)
-+
-+#else /* CONFIG_BFQ_SQ_GROUP_IOSCHED */
-+
-+#define bfq_log_bfqq(bfqd, bfqq, fmt, args...)				\
-+	pr_crit("%s bfq%d%c " fmt "\n",					\
-+		checked_dev_name((bfqd)->queue->backing_dev_info->dev),	\
-+		(bfqq)->pid, bfq_bfqq_sync((bfqq)) ? 'S' : 'A',		\
-+		##args)
-+#define bfq_log_bfqg(bfqd, bfqg, fmt, args...)		do {} while (0)
-+
-+#endif /* CONFIG_BFQ_SQ_GROUP_IOSCHED */
-+
-+#define bfq_log(bfqd, fmt, args...) \
-+	pr_crit("%s bfq " fmt "\n",					\
-+		checked_dev_name((bfqd)->queue->backing_dev_info->dev),	\
-+		##args)
-+
-+#else /* CONFIG_BFQ_REDIRECT_TO_CONSOLE */
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+static struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
-+static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
-+
-+#define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	do {			\
-+	char __pbuf[128];						\
-+									\
-+	assert_spin_locked((bfqd)->queue->queue_lock);			\
-+	blkg_path(bfqg_to_blkg(bfqq_group(bfqq)), __pbuf, sizeof(__pbuf)); \
-+	blk_add_trace_msg((bfqd)->queue, "bfq%d%c %s " fmt, \
-+			  (bfqq)->pid,			  \
-+			  bfq_bfqq_sync((bfqq)) ? 'S' : 'A',	\
-+			  __pbuf, ##args);				\
-+} while (0)
-+
-+#define bfq_log_bfqg(bfqd, bfqg, fmt, args...)	do {			\
-+	char __pbuf[128];						\
-+									\
-+	blkg_path(bfqg_to_blkg(bfqg), __pbuf, sizeof(__pbuf));		\
-+	blk_add_trace_msg((bfqd)->queue, "%s " fmt, __pbuf, ##args);	\
-+} while (0)
-+
-+#else /* CONFIG_BFQ_SQ_GROUP_IOSCHED */
-+
-+#define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	\
-+	blk_add_trace_msg((bfqd)->queue, "bfq%d%c " fmt, (bfqq)->pid,	\
-+			bfq_bfqq_sync((bfqq)) ? 'S' : 'A',		\
-+				##args)
-+#define bfq_log_bfqg(bfqd, bfqg, fmt, args...)		do {} while (0)
-+
-+#endif /* CONFIG_BFQ_SQ_GROUP_IOSCHED */
-+
-+#define bfq_log(bfqd, fmt, args...) \
-+	blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args)
-+#endif /* CONFIG_BFQ_REDIRECT_TO_CONSOLE */
-+
-+/* Expiration reasons. */
-+enum bfqq_expiration {
-+	BFQ_BFQQ_TOO_IDLE = 0,		/*
-+					 * queue has been idling for
-+					 * too long
-+					 */
-+	BFQ_BFQQ_BUDGET_TIMEOUT,	/* budget took too long to be used */
-+	BFQ_BFQQ_BUDGET_EXHAUSTED,	/* budget consumed */
-+	BFQ_BFQQ_NO_MORE_REQUESTS,	/* the queue has no more requests */
-+	BFQ_BFQQ_PREEMPTED		/* preemption in progress */
-+};
-+
-+
-+struct bfqg_stats {
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	/* number of ios merged */
-+	struct blkg_rwstat		merged;
-+	/* total time spent on device in ns, may not be accurate w/ queueing */
-+	struct blkg_rwstat		service_time;
-+	/* total time spent waiting in scheduler queue in ns */
-+	struct blkg_rwstat		wait_time;
-+	/* number of IOs queued up */
-+	struct blkg_rwstat		queued;
-+	/* total disk time and nr sectors dispatched by this group */
-+	struct blkg_stat		time;
-+	/* sum of number of ios queued across all samples */
-+	struct blkg_stat		avg_queue_size_sum;
-+	/* count of samples taken for average */
-+	struct blkg_stat		avg_queue_size_samples;
-+	/* how many times this group has been removed from service tree */
-+	struct blkg_stat		dequeue;
-+	/* total time spent waiting for it to be assigned a timeslice. */
-+	struct blkg_stat		group_wait_time;
-+	/* time spent idling for this blkcg_gq */
-+	struct blkg_stat		idle_time;
-+	/* total time with empty current active q with other requests queued */
-+	struct blkg_stat		empty_time;
-+	/* fields after this shouldn't be cleared on stat reset */
-+	uint64_t			start_group_wait_time;
-+	uint64_t			start_idle_time;
-+	uint64_t			start_empty_time;
-+	uint16_t			flags;
-+#endif
-+};
-+
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+/*
-+ * struct bfq_group_data - per-blkcg storage for the blkio subsystem.
-+ *
-+ * @ps: @blkcg_policy_storage that this structure inherits
-+ * @weight: weight of the bfq_group
-+ */
-+struct bfq_group_data {
-+	/* must be the first member */
-+	struct blkcg_policy_data pd;
-+
-+	unsigned int weight;
-+};
-+
-+/**
-+ * struct bfq_group - per (device, cgroup) data structure.
-+ * @entity: schedulable entity to insert into the parent group sched_data.
-+ * @sched_data: own sched_data, to contain child entities (they may be
-+ *              both bfq_queues and bfq_groups).
-+ * @bfqd: the bfq_data for the device this group acts upon.
-+ * @async_bfqq: array of async queues for all the tasks belonging to
-+ *              the group, one queue per ioprio value per ioprio_class,
-+ *              except for the idle class that has only one queue.
-+ * @async_idle_bfqq: async queue for the idle class (ioprio is ignored).
-+ * @my_entity: pointer to @entity, %NULL for the toplevel group; used
-+ *             to avoid too many special cases during group creation/
-+ *             migration.
-+ * @active_entities: number of active entities belonging to the group;
-+ *                   unused for the root group. Used to know whether there
-+ *                   are groups with more than one active @bfq_entity
-+ *                   (see the comments to the function
-+ *                   bfq_bfqq_may_idle()).
-+ * @rq_pos_tree: rbtree sorted by next_request position, used when
-+ *               determining if two or more queues have interleaving
-+ *               requests (see bfq_find_close_cooperator()).
-+ *
-+ * Each (device, cgroup) pair has its own bfq_group, i.e., for each cgroup
-+ * there is a set of bfq_groups, each one collecting the lower-level
-+ * entities belonging to the group that are acting on the same device.
-+ *
-+ * Locking works as follows:
-+ *    o @bfqd is protected by the queue lock, RCU is used to access it
-+ *      from the readers.
-+ *    o All the other fields are protected by the @bfqd queue lock.
-+ */
-+struct bfq_group {
-+	/* must be the first member */
-+	struct blkg_policy_data pd;
-+
-+	struct bfq_entity entity;
-+	struct bfq_sched_data sched_data;
-+
-+	void *bfqd;
-+
-+	struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
-+	struct bfq_queue *async_idle_bfqq;
-+
-+	struct bfq_entity *my_entity;
-+
-+	int active_entities;
-+
-+	struct rb_root rq_pos_tree;
-+
-+	struct bfqg_stats stats;
-+};
-+
-+#else
-+struct bfq_group {
-+	struct bfq_sched_data sched_data;
-+
-+	struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
-+	struct bfq_queue *async_idle_bfqq;
-+
-+	struct rb_root rq_pos_tree;
-+};
-+#endif
-+
-+static struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity);
-+
-+static unsigned int bfq_class_idx(struct bfq_entity *entity)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+
-+	return bfqq ? bfqq->ioprio_class - 1 :
-+		BFQ_DEFAULT_GRP_CLASS - 1;
-+}
-+
-+static struct bfq_service_tree *
-+bfq_entity_service_tree(struct bfq_entity *entity)
-+{
-+	struct bfq_sched_data *sched_data = entity->sched_data;
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+	unsigned int idx = bfq_class_idx(entity);
-+
-+	BUG_ON(idx >= BFQ_IOPRIO_CLASSES);
-+	BUG_ON(sched_data == NULL);
-+
-+	if (bfqq)
-+		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			     "entity_service_tree %p %d",
-+			     sched_data->service_tree + idx, idx);
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	else {
-+		struct bfq_group *bfqg =
-+			container_of(entity, struct bfq_group, entity);
-+
-+		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+			     "entity_service_tree %p %d",
-+			     sched_data->service_tree + idx, idx);
-+	}
-+#endif
-+	return sched_data->service_tree + idx;
-+}
-+
-+static struct bfq_queue *bic_to_bfqq(struct bfq_io_cq *bic, bool is_sync)
-+{
-+	return bic->bfqq[is_sync];
-+}
-+
-+static void bic_set_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq,
-+			 bool is_sync)
-+{
-+	bic->bfqq[is_sync] = bfqq;
-+}
-+
-+static struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic)
-+{
-+	return bic->icq.q->elevator->elevator_data;
-+}
-+
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+
-+static struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq)
-+{
-+	struct bfq_entity *group_entity = bfqq->entity.parent;
-+
-+	if (!group_entity)
-+		group_entity = &bfqq->bfqd->root_group->entity;
-+
-+	return container_of(group_entity, struct bfq_group, entity);
-+}
-+
-+#else
-+
-+static struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq)
-+{
-+	return bfqq->bfqd->root_group;
-+}
-+
-+#endif
-+
-+static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio);
-+static void bfq_put_queue(struct bfq_queue *bfqq);
-+static void bfq_dispatch_insert(struct request_queue *q, struct request *rq);
-+static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd,
-+				       struct bio *bio, bool is_sync,
-+				       struct bfq_io_cq *bic);
-+static void bfq_end_wr_async_queues(struct bfq_data *bfqd,
-+				    struct bfq_group *bfqg);
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);
-+#endif
-+static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq);
-+
-+#endif /* _BFQ_H */
-diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
-index 8da66379f7ea..bf000c58644b 100644
---- a/include/linux/blkdev.h
-+++ b/include/linux/blkdev.h
-@@ -54,7 +54,7 @@ struct blk_stat_callback;
-  * Maximum number of blkcg policies allowed to be registered concurrently.
-  * Defined here to simplify include dependency.
-  */
--#define BLKCG_MAX_POLS		3
-+#define BLKCG_MAX_POLS		4
- 
- typedef void (rq_end_io_fn)(struct request *, blk_status_t);
- 
-
-From 9916fed6c89c61a2b26053be04501784570bbec8 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Thu, 20 Jul 2017 10:46:39 +0200
-Subject: [PATCH 02/51] Add extra checks related to entity scheduling
-
-- extra checks related to ioprioi-class changes
-- specific check on st->idle in __bfq_requeue_entity
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-sched.c | 9 ++++++++-
- 1 file changed, 8 insertions(+), 1 deletion(-)
-
-diff --git a/block/bfq-sched.c b/block/bfq-sched.c
-index ac8991bca9fa..5ddf9af4261e 100644
---- a/block/bfq-sched.c
-+++ b/block/bfq-sched.c
-@@ -812,6 +812,7 @@ __bfq_entity_update_weight_prio(struct bfq_service_tree *old_st,
- 		}
- #endif
- 
-+		BUG_ON(entity->tree && update_class_too);
- 		BUG_ON(old_st->wsum < entity->weight);
- 		old_st->wsum -= entity->weight;
- 
-@@ -883,8 +884,10 @@ __bfq_entity_update_weight_prio(struct bfq_service_tree *old_st,
- 
- 		new_st->wsum += entity->weight;
- 
--		if (new_st != old_st)
-+		if (new_st != old_st) {
-+			BUG_ON(!update_class_too);
- 			entity->start = new_st->vtime;
-+		}
- 	}
- 
- 	return new_st;
-@@ -993,6 +996,7 @@ static void bfq_update_fin_time_enqueue(struct bfq_entity *entity,
- 	 * tree, then it is safe to invoke next function with the last
- 	 * parameter set (see the comments on the function).
- 	 */
-+	BUG_ON(entity->tree);
- 	st = __bfq_entity_update_weight_prio(st, entity, true);
- 	bfq_calc_finish(entity, entity->budget);
- 
-@@ -1113,9 +1117,11 @@ static void __bfq_activate_entity(struct bfq_entity *entity,
- 		 * check for that.
- 		 */
- 		bfq_idle_extract(st, entity);
-+		BUG_ON(entity->tree);
- 		entity->start = bfq_gt(min_vstart, entity->finish) ?
- 			min_vstart : entity->finish;
- 	} else {
-+		BUG_ON(entity->tree);
- 		/*
- 		 * The finish time of the entity may be invalid, and
- 		 * it is in the past for sure, otherwise the queue
-@@ -1203,6 +1209,7 @@ static void __bfq_requeue_entity(struct bfq_entity *entity)
- 		 */
- 		bfq_calc_finish(entity, entity->service);
- 		entity->start = entity->finish;
-+		BUG_ON(entity->tree && entity->tree == &st->idle);
- 		BUG_ON(entity->tree && entity->tree != &st->active);
- 		/*
- 		 * In addition, if the entity had more than one child
-
-From 8f5b2c25dcbe31dda524e85b921b3aa1fe11d111 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Fri, 21 Jul 2017 12:08:57 +0200
-Subject: [PATCH 03/51] block, bfq: reset in_service_entity if it becomes idle
-
-BFQ implements hierarchical scheduling by representing each group of
-queues with a generic parent entity. For each parent entity, BFQ
-maintains an in_service_entity pointer: if one of the child entities
-happens to be in service, in_service_entity points to it.  The
-resetting of these pointers happens only on queue expirations: when
-the in-service queue is expired, i.e., stops to be the queue in
-service, BFQ resets all in_service_entity pointers along the
-parent-entity path from this queue to the root entity.
-
-Functions handling the scheduling of entities assume, naturally, that
-in-service entities are active, i.e., have pending I/O requests (or,
-as a special case, even if they have no pending requests, they are
-expected to receive a new request very soon, with the scheduler idling
-the storage device while waiting for such an event). Unfortunately,
-the above resetting scheme of the in_service_entity pointers may cause
-this assumption to be violated.  For example, the in-service queue may
-happen to remain without requests because of a request merge. In this
-case the queue does become idle, and all related data structures are
-updated accordingly. But in_service_entity still points to the queue
-in the parent entity. This inconsistency may even propagate to
-higher-level parent entities, if they happen to become idle as well,
-as a consequence of the leaf queue becoming idle. For this queue and
-parent entities, scheduling functions have an undefined behaviour,
-and, as reported, may easily lead to kernel crashes or hangs.
-
-This commit addresses this issue by simply resetting the
-in_service_entity field also when it is detected to point to an entity
-becoming idle (regardless of why the entity becomes idle).
-
-Reported-by: Laurentiu Nicola <lnicola@dend.ro>
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
-Tested-by: Laurentiu Nicola <lnicola@dend.ro>
----
- block/bfq-sched.c | 4 +++-
- 1 file changed, 3 insertions(+), 1 deletion(-)
-
-diff --git a/block/bfq-sched.c b/block/bfq-sched.c
-index 5ddf9af4261e..a07a06eb5c72 100644
---- a/block/bfq-sched.c
-+++ b/block/bfq-sched.c
-@@ -1336,8 +1336,10 @@ static bool __bfq_deactivate_entity(struct bfq_entity *entity,
- 
- 	BUG_ON(is_in_service && entity->tree && entity->tree != &st->active);
- 
--	if (is_in_service)
-+	if (is_in_service) {
- 		bfq_calc_finish(entity, entity->service);
-+		sd->in_service_entity = NULL;
-+	}
- 
- 	if (entity->tree == &st->active)
- 		bfq_active_extract(st, entity);
-
-From 600ea668e2d340c95724bcf981d88812d6900342 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Fri, 28 Jul 2017 21:09:51 +0200
-Subject: [PATCH 04/51] block, bfq: consider also in_service_entity to state
- whether an entity is active
-
-Groups of BFQ queues are represented by generic entities in BFQ. When
-a queue belonging to a parent entity is deactivated, the parent entity
-may need to be deactivated too, in case the deactivated queue was the
-only active queue for the parent entity. This deactivation may need to
-be propagated upwards if the entity belongs, in its turn, to a further
-higher-level entity, and so on. In particular, the upward propagation
-of deactivation stops at the first parent entity that remains active
-even if one of its child entities has been deactivated.
-
-To decide whether the last non-deactivation condition holds for a
-parent entity, BFQ checks whether the field next_in_service is still
-not NULL for the parent entity, after the deactivation of one of its
-child entity. If it is not NULL, then there are certainly other active
-entities in the parent entity, and deactivations can stop.
-
-Unfortunately, this check misses a corner case: if in_service_entity
-is not NULL, then next_in_service may happen to be NULL, although the
-parent entity is evidently active. This happens if: 1) the entity
-pointed by in_service_entity is the only active entity in the parent
-entity, and 2) according to the definition of next_in_service, the
-in_service_entity cannot be considered as next_in_service. See the
-comments on the definition of next_in_service for details on this
-second point.
-
-Hitting the above corner case causes crashes.
-
-To address this issue, this commit:
-1) Extends the above check on only next_in_service to controlling both
-next_in_service and in_service_entity (if any of them is not NULL,
-then no further deactivation is performed)
-2) Improves the (important) comments on how next_in_service is defined
-and updated; in particular it fixes a few rather obscure paragraphs
-
-Reported-by: Eric Wheeler <bfq-sched@lists.ewheeler.net>
-Reported-by: Rick Yiu <rick_yiu@htc.com>
-Reported-by: Tom X Nguyen <tom81094@gmail.com>
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
-Tested-by: Eric Wheeler <bfq-sched@lists.ewheeler.net>
-Tested-by: Rick Yiu <rick_yiu@htc.com>
-Tested-by: Laurentiu Nicola <lnicola@dend.ro>
-Tested-by: Tom X Nguyen <tom81094@gmail.com>
----
- block/bfq-sched.c | 140 ++++++++++++++++++++++++++++++------------------------
- block/bfq.h       |  23 +++++++--
- 2 files changed, 95 insertions(+), 68 deletions(-)
-
-diff --git a/block/bfq-sched.c b/block/bfq-sched.c
-index a07a06eb5c72..5c0f9290a79c 100644
---- a/block/bfq-sched.c
-+++ b/block/bfq-sched.c
-@@ -196,21 +196,23 @@ static bool bfq_update_parent_budget(struct bfq_entity *next_in_service)
- 
- /*
-  * This function tells whether entity stops being a candidate for next
-- * service, according to the following logic.
-+ * service, according to the restrictive definition of the field
-+ * next_in_service. In particular, this function is invoked for an
-+ * entity that is about to be set in service.
-  *
-- * This function is invoked for an entity that is about to be set in
-- * service. If such an entity is a queue, then the entity is no longer
-- * a candidate for next service (i.e, a candidate entity to serve
-- * after the in-service entity is expired). The function then returns
-- * true.
-+ * If entity is a queue, then the entity is no longer a candidate for
-+ * next service according to the that definition, because entity is
-+ * about to become the in-service queue. This function then returns
-+ * true if entity is a queue.
-  *
-- * In contrast, the entity could stil be a candidate for next service
-- * if it is not a queue, and has more than one child. In fact, even if
-- * one of its children is about to be set in service, other children
-- * may still be the next to serve. As a consequence, a non-queue
-- * entity is not a candidate for next-service only if it has only one
-- * child. And only if this condition holds, then the function returns
-- * true for a non-queue entity.
-+ * In contrast, entity could still be a candidate for next service if
-+ * it is not a queue, and has more than one active child. In fact,
-+ * even if one of its children is about to be set in service, other
-+ * active children may still be the next to serve, for the parent
-+ * entity, even according to the above definition. As a consequence, a
-+ * non-queue entity is not a candidate for next-service only if it has
-+ * only one active child. And only if this condition holds, then this
-+ * function returns true for a non-queue entity.
-  */
- static bool bfq_no_longer_next_in_service(struct bfq_entity *entity)
- {
-@@ -223,6 +225,18 @@ static bool bfq_no_longer_next_in_service(struct bfq_entity *entity)
- 
- 	BUG_ON(bfqg == ((struct bfq_data *)(bfqg->bfqd))->root_group);
- 	BUG_ON(bfqg->active_entities == 0);
-+	/*
-+	 * The field active_entities does not always contain the
-+	 * actual number of active children entities: it happens to
-+	 * not account for the in-service entity in case the latter is
-+	 * removed from its active tree (which may get done after
-+	 * invoking the function bfq_no_longer_next_in_service in
-+	 * bfq_get_next_queue). Fortunately, here, i.e., while
-+	 * bfq_no_longer_next_in_service is not yet completed in
-+	 * bfq_get_next_queue, bfq_active_extract has not yet been
-+	 * invoked, and thus active_entities still coincides with the
-+	 * actual number of active entities.
-+	 */
- 	if (bfqg->active_entities == 1)
- 		return true;
- 
-@@ -1089,7 +1103,7 @@ static void bfq_update_fin_time_enqueue(struct bfq_entity *entity,
-  * one of its children receives a new request.
-  *
-  * Basically, this function updates the timestamps of entity and
-- * inserts entity into its active tree, ater possible extracting it
-+ * inserts entity into its active tree, ater possibly extracting it
-  * from its idle tree.
-  */
- static void __bfq_activate_entity(struct bfq_entity *entity,
-@@ -1213,7 +1227,7 @@ static void __bfq_requeue_entity(struct bfq_entity *entity)
- 		BUG_ON(entity->tree && entity->tree != &st->active);
- 		/*
- 		 * In addition, if the entity had more than one child
--		 * when set in service, then was not extracted from
-+		 * when set in service, then it was not extracted from
- 		 * the active tree. This implies that the position of
- 		 * the entity in the active tree may need to be
- 		 * changed now, because we have just updated the start
-@@ -1221,9 +1235,8 @@ static void __bfq_requeue_entity(struct bfq_entity *entity)
- 		 * time in a moment (the requeueing is then, more
- 		 * precisely, a repositioning in this case). To
- 		 * implement this repositioning, we: 1) dequeue the
--		 * entity here, 2) update the finish time and
--		 * requeue the entity according to the new
--		 * timestamps below.
-+		 * entity here, 2) update the finish time and requeue
-+		 * the entity according to the new timestamps below.
- 		 */
- 		if (entity->tree)
- 			bfq_active_extract(st, entity);
-@@ -1270,9 +1283,9 @@ static void __bfq_activate_requeue_entity(struct bfq_entity *entity,
- 
- 
- /**
-- * bfq_activate_entity - activate or requeue an entity representing a bfq_queue,
-- *			 and activate, requeue or reposition all ancestors
-- *			 for which such an update becomes necessary.
-+ * bfq_activate_requeue_entity - activate or requeue an entity representing a bfq_queue,
-+ *			 	 and activate, requeue or reposition all ancestors
-+ *			 	 for which such an update becomes necessary.
-  * @entity: the entity to activate.
-  * @non_blocking_wait_rq: true if this entity was waiting for a request
-  * @requeue: true if this is a requeue, which implies that bfqq is
-@@ -1308,9 +1321,9 @@ static void bfq_activate_requeue_entity(struct bfq_entity *entity,
-  * @ins_into_idle_tree: if false, the entity will not be put into the
-  *			idle tree.
-  *
-- * Deactivates an entity, independently from its previous state.  Must
-+ * Deactivates an entity, independently of its previous state.  Must
-  * be invoked only if entity is on a service tree. Extracts the entity
-- * from that tree, and if necessary and allowed, puts it on the idle
-+ * from that tree, and if necessary and allowed, puts it into the idle
-  * tree.
-  */
- static bool __bfq_deactivate_entity(struct bfq_entity *entity,
-@@ -1359,7 +1372,7 @@ static bool __bfq_deactivate_entity(struct bfq_entity *entity,
- /**
-  * bfq_deactivate_entity - deactivate an entity representing a bfq_queue.
-  * @entity: the entity to deactivate.
-- * @ins_into_idle_tree: true if the entity can be put on the idle tree
-+ * @ins_into_idle_tree: true if the entity can be put into the idle tree
-  */
- static void bfq_deactivate_entity(struct bfq_entity *entity,
- 				  bool ins_into_idle_tree,
-@@ -1406,16 +1419,29 @@ static void bfq_deactivate_entity(struct bfq_entity *entity,
- 			 */
- 			bfq_update_next_in_service(sd, NULL);
- 
--		if (sd->next_in_service) {
-+		if (sd->next_in_service || sd->in_service_entity) {
- 			/*
--			 * The parent entity is still backlogged,
--			 * because next_in_service is not NULL. So, no
--			 * further upwards deactivation must be
--			 * performed.  Yet, next_in_service has
--			 * changed.  Then the schedule does need to be
--			 * updated upwards.
-+			 * The parent entity is still active, because
-+			 * either next_in_service or in_service_entity
-+			 * is not NULL. So, no further upwards
-+			 * deactivation must be performed.  Yet,
-+			 * next_in_service has changed.  Then the
-+			 * schedule does need to be updated upwards.
-+			 *
-+			 * NOTE If in_service_entity is not NULL, then
-+			 * next_in_service may happen to be NULL,
-+			 * although the parent entity is evidently
-+			 * active. This happens if 1) the entity
-+			 * pointed by in_service_entity is the only
-+			 * active entity in the parent entity, and 2)
-+			 * according to the definition of
-+			 * next_in_service, the in_service_entity
-+			 * cannot be considered as
-+			 * next_in_service. See the comments on the
-+			 * definition of next_in_service for details.
- 			 */
- 			BUG_ON(sd->next_in_service == entity);
-+			BUG_ON(sd->in_service_entity == entity);
- 			break;
- 		}
- 
-@@ -1806,45 +1832,33 @@ static struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd)
- 
- 		/*
- 		 * If entity is no longer a candidate for next
--		 * service, then we extract it from its active tree,
--		 * for the following reason. To further boost the
--		 * throughput in some special case, BFQ needs to know
--		 * which is the next candidate entity to serve, while
--		 * there is already an entity in service. In this
--		 * respect, to make it easy to compute/update the next
--		 * candidate entity to serve after the current
--		 * candidate has been set in service, there is a case
--		 * where it is necessary to extract the current
--		 * candidate from its service tree. Such a case is
--		 * when the entity just set in service cannot be also
--		 * a candidate for next service. Details about when
--		 * this conditions holds are reported in the comments
--		 * on the function bfq_no_longer_next_in_service()
--		 * invoked below.
-+		 * service, then it must be extracted from its active
-+		 * tree, so as to make sure that it won't be
-+		 * considered when computing next_in_service. See the
-+		 * comments on the function
-+		 * bfq_no_longer_next_in_service() for details.
- 		 */
- 		if (bfq_no_longer_next_in_service(entity))
- 			bfq_active_extract(bfq_entity_service_tree(entity),
- 					   entity);
- 
- 		/*
--		 * For the same reason why we may have just extracted
--		 * entity from its active tree, we may need to update
--		 * next_in_service for the sched_data of entity too,
--		 * regardless of whether entity has been extracted.
--		 * In fact, even if entity has not been extracted, a
--		 * descendant entity may get extracted. Such an event
--		 * would cause a change in next_in_service for the
--		 * level of the descendant entity, and thus possibly
--		 * back to upper levels.
-+		 * Even if entity is not to be extracted according to
-+		 * the above check, a descendant entity may get
-+		 * extracted in one of the next iterations of this
-+		 * loop. Such an event could cause a change in
-+		 * next_in_service for the level of the descendant
-+		 * entity, and thus possibly back to this level.
- 		 *
--		 * We cannot perform the resulting needed update
--		 * before the end of this loop, because, to know which
--		 * is the correct next-to-serve candidate entity for
--		 * each level, we need first to find the leaf entity
--		 * to set in service. In fact, only after we know
--		 * which is the next-to-serve leaf entity, we can
--		 * discover whether the parent entity of the leaf
--		 * entity becomes the next-to-serve, and so on.
-+		 * However, we cannot perform the resulting needed
-+		 * update of next_in_service for this level before the
-+		 * end of the whole loop, because, to know which is
-+		 * the correct next-to-serve candidate entity for each
-+		 * level, we need first to find the leaf entity to set
-+		 * in service. In fact, only after we know which is
-+		 * the next-to-serve leaf entity, we can discover
-+		 * whether the parent entity of the leaf entity
-+		 * becomes the next-to-serve, and so on.
- 		 */
- 
- 		/* Log some information */
-diff --git a/block/bfq.h b/block/bfq.h
-index f5751ea59d98..ebd9688b9f61 100644
---- a/block/bfq.h
-+++ b/block/bfq.h
-@@ -68,17 +68,30 @@ struct bfq_service_tree {
-  *
-  * bfq_sched_data is the basic scheduler queue.  It supports three
-  * ioprio_classes, and can be used either as a toplevel queue or as an
-- * intermediate queue on a hierarchical setup.  @next_in_service
-- * points to the active entity of the sched_data service trees that
-- * will be scheduled next. It is used to reduce the number of steps
-- * needed for each hierarchical-schedule update.
-+ * intermediate queue in a hierarchical setup.
-  *
-  * The supported ioprio_classes are the same as in CFQ, in descending
-  * priority order, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE.
-  * Requests from higher priority queues are served before all the
-  * requests from lower priority queues; among requests of the same
-  * queue requests are served according to B-WF2Q+.
-- * All the fields are protected by the queue lock of the containing bfqd.
-+ *
-+ * The schedule is implemented by the service trees, plus the field
-+ * @next_in_service, which points to the entity on the active trees
-+ * that will be served next, if 1) no changes in the schedule occurs
-+ * before the current in-service entity is expired, 2) the in-service
-+ * queue becomes idle when it expires, and 3) if the entity pointed by
-+ * in_service_entity is not a queue, then the in-service child entity
-+ * of the entity pointed by in_service_entity becomes idle on
-+ * expiration. This peculiar definition allows for the following
-+ * optimization, not yet exploited: while a given entity is still in
-+ * service, we already know which is the best candidate for next
-+ * service among the other active entitities in the same parent
-+ * entity. We can then quickly compare the timestamps of the
-+ * in-service entity with those of such best candidate.
-+ *
-+ * All the fields are protected by the queue lock of the containing
-+ * bfqd.
-  */
- struct bfq_sched_data {
- 	struct bfq_entity *in_service_entity;  /* entity in service */
-
-From 6b5effd10bc6711a862e7cbd7cd2dd0146defa01 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Thu, 4 May 2017 10:53:43 +0200
-Subject: [PATCH 05/51] block, bfq: improve and refactor throughput-boosting
- logic
-
-When a queue associated with a process remains empty, there are cases
-where throughput gets boosted if the device is idled to await the
-arrival of a new I/O request for that queue. Currently, BFQ assumes
-that one of these cases is when the device has no internal queueing
-(regardless of the properties of the I/O being served). Unfortunately,
-this condition has proved to be too general. So, this commit refines it
-as "the device has no internal queueing and is rotational".
-
-This refinement provides a significant throughput boost with random
-I/O, on flash-based storage without internal queueing. For example, on
-a HiKey board, throughput increases by up to 125%, growing, e.g., from
-6.9MB/s to 15.6MB/s with two or three random readers in parallel.
-
-This commit also refactors the code related to device idling, for the
-following reason. Finding the change that provides the above large
-improvement has been slightly more difficult than it had to be,
-because the logic that decides whether to idle the device is still
-scattered across three functions. Almost all of the logic is in the
-function bfq_bfqq_may_idle, but (1) part of the decision is made in
-bfq_update_idle_window, and (2) the function bfq_bfqq_must_idle may
-switch off idling regardless of the output of bfq_bfqq_may_idle. In
-addition, both bfq_update_idle_window and bfq_bfqq_must_idle make
-their decisions as a function of parameters that are used, for similar
-purposes, also in bfq_bfqq_may_idle. This commit addresses this issue
-by moving all the logic into bfq_bfqq_may_idle.
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
-Signed-off-by: Luca Miccio <lucmiccio@gmail.com>
----
- block/bfq-sq-iosched.c | 141 +++++++++++++++++++++++++++----------------------
- block/bfq.h            |  12 ++---
- 2 files changed, 83 insertions(+), 70 deletions(-)
-
-diff --git a/block/bfq-sq-iosched.c b/block/bfq-sq-iosched.c
-index 65e7c7e77f3c..30d019fc67e0 100644
---- a/block/bfq-sq-iosched.c
-+++ b/block/bfq-sq-iosched.c
-@@ -684,10 +684,10 @@ bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_data *bfqd,
- 	unsigned int old_wr_coeff;
- 	bool busy = bfq_already_existing && bfq_bfqq_busy(bfqq);
- 
--	if (bic->saved_idle_window)
--		bfq_mark_bfqq_idle_window(bfqq);
-+	if (bic->saved_has_short_ttime)
-+		bfq_mark_bfqq_has_short_ttime(bfqq);
- 	else
--		bfq_clear_bfqq_idle_window(bfqq);
-+		bfq_clear_bfqq_has_short_ttime(bfqq);
- 
- 	if (bic->saved_IO_bound)
- 		bfq_mark_bfqq_IO_bound(bfqq);
-@@ -2047,7 +2047,7 @@ static void bfq_bfqq_save_state(struct bfq_queue *bfqq)
- 	if (!bic)
- 		return;
- 
--	bic->saved_idle_window = bfq_bfqq_idle_window(bfqq);
-+	bic->saved_has_short_ttime = bfq_bfqq_has_short_ttime(bfqq);
- 	bic->saved_IO_bound = bfq_bfqq_IO_bound(bfqq);
- 	bic->saved_in_large_burst = bfq_bfqq_in_large_burst(bfqq);
- 	bic->was_in_burst_list = !hlist_unhashed(&bfqq->burst_list_node);
-@@ -3214,9 +3214,9 @@ static void bfq_bfqq_expire(struct bfq_data *bfqd,
- 	}
- 
- 	bfq_log_bfqq(bfqd, bfqq,
--		"expire (%d, slow %d, num_disp %d, idle_win %d, weight %d)",
-+		"expire (%d, slow %d, num_disp %d, short_ttime %d, weight %d)",
- 		     reason, slow, bfqq->dispatched,
--		     bfq_bfqq_idle_window(bfqq), entity->weight);
-+		     bfq_bfqq_has_short_ttime(bfqq), entity->weight);
- 
- 	/*
- 	 * Increase, decrease or leave budget unchanged according to
-@@ -3298,7 +3298,10 @@ static bool bfq_may_expire_for_budg_timeout(struct bfq_queue *bfqq)
- static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq)
- {
- 	struct bfq_data *bfqd = bfqq->bfqd;
--	bool idling_boosts_thr, idling_boosts_thr_without_issues,
-+	bool rot_without_queueing =
-+		!blk_queue_nonrot(bfqd->queue) && !bfqd->hw_tag,
-+		bfqq_sequential_and_IO_bound,
-+		idling_boosts_thr, idling_boosts_thr_without_issues,
- 		idling_needed_for_service_guarantees,
- 		asymmetric_scenario;
- 
-@@ -3306,27 +3309,44 @@ static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq)
- 		return true;
- 
- 	/*
-+	 * Idling is performed only if slice_idle > 0. In addition, we
-+	 * do not idle if
-+	 * (a) bfqq is async
-+	 * (b) bfqq is in the idle io prio class: in this case we do
-+	 * not idle because we want to minimize the bandwidth that
-+	 * queues in this class can steal to higher-priority queues
-+	 */
-+	if (bfqd->bfq_slice_idle == 0 || !bfq_bfqq_sync(bfqq) ||
-+	   bfq_class_idle(bfqq))
-+		return false;
-+
-+	bfqq_sequential_and_IO_bound = !BFQQ_SEEKY(bfqq) &&
-+		bfq_bfqq_IO_bound(bfqq) && bfq_bfqq_has_short_ttime(bfqq);
-+	/*
- 	 * The next variable takes into account the cases where idling
- 	 * boosts the throughput.
- 	 *
- 	 * The value of the variable is computed considering, first, that
- 	 * idling is virtually always beneficial for the throughput if:
--	 * (a) the device is not NCQ-capable, or
--	 * (b) regardless of the presence of NCQ, the device is rotational
--	 *     and the request pattern for bfqq is I/O-bound and sequential.
-+	 * (a) the device is not NCQ-capable and rotational, or
-+	 * (b) regardless of the presence of NCQ, the device is rotational and
-+	 *     the request pattern for bfqq is I/O-bound and sequential, or
-+	 * (c) regardless of whether it is rotational, the device is
-+	 *     not NCQ-capable and the request pattern for bfqq is
-+	 *     I/O-bound and sequential.
- 	 *
- 	 * Secondly, and in contrast to the above item (b), idling an
- 	 * NCQ-capable flash-based device would not boost the
- 	 * throughput even with sequential I/O; rather it would lower
- 	 * the throughput in proportion to how fast the device
- 	 * is. Accordingly, the next variable is true if any of the
--	 * above conditions (a) and (b) is true, and, in particular,
--	 * happens to be false if bfqd is an NCQ-capable flash-based
--	 * device.
-+	 * above conditions (a), (b) or (c) is true, and, in
-+	 * particular, happens to be false if bfqd is an NCQ-capable
-+	 * flash-based device.
- 	 */
--	idling_boosts_thr = !bfqd->hw_tag ||
--		(!blk_queue_nonrot(bfqd->queue) && bfq_bfqq_IO_bound(bfqq) &&
--		 bfq_bfqq_idle_window(bfqq));
-+	idling_boosts_thr = rot_without_queueing ||
-+		((!blk_queue_nonrot(bfqd->queue) || !bfqd->hw_tag) &&
-+		 bfqq_sequential_and_IO_bound);
- 
- 	/*
- 	 * The value of the next variable,
-@@ -3497,12 +3517,10 @@ static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq)
- 		asymmetric_scenario && !bfq_bfqq_in_large_burst(bfqq);
- 
- 	/*
--	 * We have now all the components we need to compute the return
--	 * value of the function, which is true only if both the following
--	 * conditions hold:
--	 * 1) bfqq is sync, because idling make sense only for sync queues;
--	 * 2) idling either boosts the throughput (without issues), or
--	 *    is necessary to preserve service guarantees.
-+	 * We have now all the components we need to compute the
-+	 * return value of the function, which is true only if idling
-+	 * either boosts the throughput (without issues), or is
-+	 * necessary to preserve service guarantees.
- 	 */
- 	bfq_log_bfqq(bfqd, bfqq, "may_idle: sync %d idling_boosts_thr %d",
- 		     bfq_bfqq_sync(bfqq), idling_boosts_thr);
-@@ -3514,9 +3532,8 @@ static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq)
- 		     bfq_bfqq_IO_bound(bfqq),
- 		     idling_needed_for_service_guarantees);
- 
--	return bfq_bfqq_sync(bfqq) &&
--		(idling_boosts_thr_without_issues ||
--		 idling_needed_for_service_guarantees);
-+	return idling_boosts_thr_without_issues ||
-+		idling_needed_for_service_guarantees;
- }
- 
- /*
-@@ -3532,10 +3549,7 @@ static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq)
-  */
- static bool bfq_bfqq_must_idle(struct bfq_queue *bfqq)
- {
--	struct bfq_data *bfqd = bfqq->bfqd;
--
--	return RB_EMPTY_ROOT(&bfqq->sort_list) && bfqd->bfq_slice_idle != 0 &&
--	       bfq_bfqq_may_idle(bfqq);
-+	return RB_EMPTY_ROOT(&bfqq->sort_list) && bfq_bfqq_may_idle(bfqq);
- }
- 
- /*
-@@ -3994,7 +4008,6 @@ static void bfq_set_next_ioprio_data(struct bfq_queue *bfqq,
- 	case IOPRIO_CLASS_IDLE:
- 		bfqq->new_ioprio_class = IOPRIO_CLASS_IDLE;
- 		bfqq->new_ioprio = 7;
--		bfq_clear_bfqq_idle_window(bfqq);
- 		break;
- 	}
- 
-@@ -4058,8 +4071,14 @@ static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 		bfq_set_next_ioprio_data(bfqq, bic);
- 
- 	if (is_sync) {
-+		/*
-+		 * No need to mark as has_short_ttime if in
-+		 * idle_class, because no device idling is performed
-+		 * for queues in idle class
-+		 */
- 		if (!bfq_class_idle(bfqq))
--			bfq_mark_bfqq_idle_window(bfqq);
-+			/* tentatively mark as has_short_ttime */
-+			bfq_mark_bfqq_has_short_ttime(bfqq);
- 		bfq_mark_bfqq_sync(bfqq);
- 		bfq_mark_bfqq_just_created(bfqq);
- 	} else
-@@ -4195,18 +4214,19 @@ bfq_update_io_seektime(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 		 blk_rq_sectors(rq) < BFQQ_SECT_THR_NONROT);
- }
- 
--/*
-- * Disable idle window if the process thinks too long or seeks so much that
-- * it doesn't matter.
-- */
--static void bfq_update_idle_window(struct bfq_data *bfqd,
--				   struct bfq_queue *bfqq,
--				   struct bfq_io_cq *bic)
-+static void bfq_update_has_short_ttime(struct bfq_data *bfqd,
-+				       struct bfq_queue *bfqq,
-+				       struct bfq_io_cq *bic)
- {
--	int enable_idle;
-+	bool has_short_ttime = true;
- 
--	/* Don't idle for async or idle io prio class. */
--	if (!bfq_bfqq_sync(bfqq) || bfq_class_idle(bfqq))
-+	/*
-+	 * No need to update has_short_ttime if bfqq is async or in
-+	 * idle io prio class, or if bfq_slice_idle is zero, because
-+	 * no device idling is performed for bfqq in this case.
-+	 */
-+	if (!bfq_bfqq_sync(bfqq) || bfq_class_idle(bfqq) ||
-+	    bfqd->bfq_slice_idle == 0)
- 		return;
- 
- 	/* Idle window just restored, statistics are meaningless. */
-@@ -4214,27 +4234,22 @@ static void bfq_update_idle_window(struct bfq_data *bfqd,
- 				     bfqd->bfq_wr_min_idle_time))
- 		return;
- 
--	enable_idle = bfq_bfqq_idle_window(bfqq);
--
-+	/* Think time is infinite if no process is linked to
-+	 * bfqq. Otherwise check average think time to
-+	 * decide whether to mark as has_short_ttime
-+	 */
- 	if (atomic_read(&bic->icq.ioc->active_ref) == 0 ||
--	    bfqd->bfq_slice_idle == 0 ||
--		(bfqd->hw_tag && BFQQ_SEEKY(bfqq) &&
--			bfqq->wr_coeff == 1))
--		enable_idle = 0;
--	else if (bfq_sample_valid(bic->ttime.ttime_samples)) {
--		if (bic->ttime.ttime_mean > bfqd->bfq_slice_idle &&
--			bfqq->wr_coeff == 1)
--			enable_idle = 0;
--		else
--			enable_idle = 1;
--	}
--	bfq_log_bfqq(bfqd, bfqq, "update_idle_window: enable_idle %d",
--		enable_idle);
-+	    (bfq_sample_valid(bic->ttime.ttime_samples) &&
-+	     bic->ttime.ttime_mean > bfqd->bfq_slice_idle))
-+		has_short_ttime = false;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "update_has_short_ttime: has_short_ttime %d",
-+		has_short_ttime);
- 
--	if (enable_idle)
--		bfq_mark_bfqq_idle_window(bfqq);
-+	if (has_short_ttime)
-+		bfq_mark_bfqq_has_short_ttime(bfqq);
- 	else
--		bfq_clear_bfqq_idle_window(bfqq);
-+		bfq_clear_bfqq_has_short_ttime(bfqq);
- }
- 
- /*
-@@ -4250,14 +4265,12 @@ static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 		bfqq->meta_pending++;
- 
- 	bfq_update_io_thinktime(bfqd, bic);
-+	bfq_update_has_short_ttime(bfqd, bfqq, bic);
- 	bfq_update_io_seektime(bfqd, bfqq, rq);
--	if (bfqq->entity.service > bfq_max_budget(bfqd) / 8 ||
--	    !BFQQ_SEEKY(bfqq))
--		bfq_update_idle_window(bfqd, bfqq, bic);
- 
- 	bfq_log_bfqq(bfqd, bfqq,
--		     "rq_enqueued: idle_window=%d (seeky %d)",
--		     bfq_bfqq_idle_window(bfqq), BFQQ_SEEKY(bfqq));
-+		     "rq_enqueued: has_short_ttime=%d (seeky %d)",
-+		     bfq_bfqq_has_short_ttime(bfqq), BFQQ_SEEKY(bfqq));
- 
- 	bfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
- 
-diff --git a/block/bfq.h b/block/bfq.h
-index ebd9688b9f61..34fc4697fd89 100644
---- a/block/bfq.h
-+++ b/block/bfq.h
-@@ -349,11 +349,11 @@ struct bfq_io_cq {
- #endif
- 
- 	/*
--	 * Snapshot of the idle window before merging; taken to
--	 * remember this value while the queue is merged, so as to be
--	 * able to restore it in case of split.
-+	 * Snapshot of the has_short_time flag before merging; taken
-+	 * to remember its value while the queue is merged, so as to
-+	 * be able to restore it in case of split.
- 	 */
--	bool saved_idle_window;
-+	bool saved_has_short_ttime;
- 	/*
- 	 * Same purpose as the previous two fields for the I/O bound
- 	 * classification of a queue.
-@@ -610,7 +610,7 @@ enum bfqq_state_flags {
- 					     */
- 	BFQ_BFQQ_FLAG_must_alloc,	/* must be allowed rq alloc */
- 	BFQ_BFQQ_FLAG_fifo_expire,	/* FIFO checked in this slice */
--	BFQ_BFQQ_FLAG_idle_window,	/* slice idling enabled */
-+	BFQ_BFQQ_FLAG_has_short_ttime,	/* queue has a short think time */
- 	BFQ_BFQQ_FLAG_sync,		/* synchronous queue */
- 	BFQ_BFQQ_FLAG_IO_bound,		/*
- 					 * bfqq has timed-out at least once
-@@ -649,7 +649,7 @@ BFQ_BFQQ_FNS(wait_request);
- BFQ_BFQQ_FNS(non_blocking_wait_rq);
- BFQ_BFQQ_FNS(must_alloc);
- BFQ_BFQQ_FNS(fifo_expire);
--BFQ_BFQQ_FNS(idle_window);
-+BFQ_BFQQ_FNS(has_short_ttime);
- BFQ_BFQQ_FNS(sync);
- BFQ_BFQQ_FNS(IO_bound);
- BFQ_BFQQ_FNS(in_large_burst);
-
-From b5e746fa99d961a5642cffb27c19a77e8b638007 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Mon, 19 Dec 2016 16:59:33 +0100
-Subject: [PATCH 06/51] FIRST BFQ-MQ COMMIT: Copy bfq-sq-iosched.c as
- bfq-mq-iosched.c
-
-This commit introduces bfq-mq-iosched.c, the main source file that
-will contain the code of bfq for blk-mq. I name tentatively
-bfq-mq this version of bfq.
-
-For the moment, the file bfq-mq-iosched.c is just a copy of
-bfq-sq-iosched.c, i.e, of the main source file of bfq for blk.
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-mq-iosched.c | 5392 ++++++++++++++++++++++++++++++++++++++++++++++++
- 1 file changed, 5392 insertions(+)
- create mode 100644 block/bfq-mq-iosched.c
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-new file mode 100644
-index 000000000000..30d019fc67e0
---- /dev/null
-+++ b/block/bfq-mq-iosched.c
-@@ -0,0 +1,5392 @@
-+/*
-+ * Budget Fair Queueing (BFQ) I/O scheduler.
-+ *
-+ * Based on ideas and code from CFQ:
-+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
-+ *
-+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
-+ *		      Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2017 Paolo Valente <paolo.valente@linaro.org>
-+ *
-+ * Licensed under the GPL-2 as detailed in the accompanying COPYING.BFQ
-+ * file.
-+ *
-+ * BFQ is a proportional-share I/O scheduler, with some extra
-+ * low-latency capabilities. BFQ also supports full hierarchical
-+ * scheduling through cgroups. Next paragraphs provide an introduction
-+ * on BFQ inner workings. Details on BFQ benefits and usage can be
-+ * found in Documentation/block/bfq-iosched.txt.
-+ *
-+ * BFQ is a proportional-share storage-I/O scheduling algorithm based
-+ * on the slice-by-slice service scheme of CFQ. But BFQ assigns
-+ * budgets, measured in number of sectors, to processes instead of
-+ * time slices. The device is not granted to the in-service process
-+ * for a given time slice, but until it has exhausted its assigned
-+ * budget. This change from the time to the service domain enables BFQ
-+ * to distribute the device throughput among processes as desired,
-+ * without any distortion due to throughput fluctuations, or to device
-+ * internal queueing. BFQ uses an ad hoc internal scheduler, called
-+ * B-WF2Q+, to schedule processes according to their budgets. More
-+ * precisely, BFQ schedules queues associated with processes. Thanks to
-+ * the accurate policy of B-WF2Q+, BFQ can afford to assign high
-+ * budgets to I/O-bound processes issuing sequential requests (to
-+ * boost the throughput), and yet guarantee a low latency to
-+ * interactive and soft real-time applications.
-+ *
-+ * NOTE: if the main or only goal, with a given device, is to achieve
-+ * the maximum-possible throughput at all times, then do switch off
-+ * all low-latency heuristics for that device, by setting low_latency
-+ * to 0.
-+ *
-+ * BFQ is described in [1], where also a reference to the initial, more
-+ * theoretical paper on BFQ can be found. The interested reader can find
-+ * in the latter paper full details on the main algorithm, as well as
-+ * formulas of the guarantees and formal proofs of all the properties.
-+ * With respect to the version of BFQ presented in these papers, this
-+ * implementation adds a few more heuristics, such as the one that
-+ * guarantees a low latency to soft real-time applications, and a
-+ * hierarchical extension based on H-WF2Q+.
-+ *
-+ * B-WF2Q+ is based on WF2Q+, that is described in [2], together with
-+ * H-WF2Q+, while the augmented tree used to implement B-WF2Q+ with O(log N)
-+ * complexity derives from the one introduced with EEVDF in [3].
-+ *
-+ * [1] P. Valente, A. Avanzini, "Evolution of the BFQ Storage I/O
-+ *   Scheduler", Proceedings of the First Workshop on Mobile System
-+ *   Technologies (MST-2015), May 2015.
-+ *   http://algogroup.unimore.it/people/paolo/disk_sched/mst-2015.pdf
-+ *
-+ * http://algogroup.unimo.it/people/paolo/disk_sched/bf1-v1-suite-results.pdf
-+ *
-+ * [2] Jon C.R. Bennett and H. Zhang, ``Hierarchical Packet Fair Queueing
-+ *     Algorithms,'' IEEE/ACM Transactions on Networking, 5(5):675-689,
-+ *     Oct 1997.
-+ *
-+ * http://www.cs.cmu.edu/~hzhang/papers/TON-97-Oct.ps.gz
-+ *
-+ * [3] I. Stoica and H. Abdel-Wahab, ``Earliest Eligible Virtual Deadline
-+ *     First: A Flexible and Accurate Mechanism for Proportional Share
-+ *     Resource Allocation,'' technical report.
-+ *
-+ * http://www.cs.berkeley.edu/~istoica/papers/eevdf-tr-95.pdf
-+ */
-+#include <linux/module.h>
-+#include <linux/slab.h>
-+#include <linux/blkdev.h>
-+#include <linux/cgroup.h>
-+#include <linux/elevator.h>
-+#include <linux/jiffies.h>
-+#include <linux/rbtree.h>
-+#include <linux/ioprio.h>
-+#include "blk.h"
-+#include "bfq.h"
-+
-+/* Expiration time of sync (0) and async (1) requests, in ns. */
-+static const u64 bfq_fifo_expire[2] = { NSEC_PER_SEC / 4, NSEC_PER_SEC / 8 };
-+
-+/* Maximum backwards seek, in KiB. */
-+static const int bfq_back_max = (16 * 1024);
-+
-+/* Penalty of a backwards seek, in number of sectors. */
-+static const int bfq_back_penalty = 2;
-+
-+/* Idling period duration, in ns. */
-+static u32 bfq_slice_idle = (NSEC_PER_SEC / 125);
-+
-+/* Minimum number of assigned budgets for which stats are safe to compute. */
-+static const int bfq_stats_min_budgets = 194;
-+
-+/* Default maximum budget values, in sectors and number of requests. */
-+static const int bfq_default_max_budget = (16 * 1024);
-+
-+/*
-+ * Async to sync throughput distribution is controlled as follows:
-+ * when an async request is served, the entity is charged the number
-+ * of sectors of the request, multiplied by the factor below
-+ */
-+static const int bfq_async_charge_factor = 10;
-+
-+/* Default timeout values, in jiffies, approximating CFQ defaults. */
-+static const int bfq_timeout = (HZ / 8);
-+
-+static struct kmem_cache *bfq_pool;
-+
-+/* Below this threshold (in ns), we consider thinktime immediate. */
-+#define BFQ_MIN_TT		(2 * NSEC_PER_MSEC)
-+
-+/* hw_tag detection: parallel requests threshold and min samples needed. */
-+#define BFQ_HW_QUEUE_THRESHOLD	4
-+#define BFQ_HW_QUEUE_SAMPLES	32
-+
-+#define BFQQ_SEEK_THR		(sector_t)(8 * 100)
-+#define BFQQ_SECT_THR_NONROT	(sector_t)(2 * 32)
-+#define BFQQ_CLOSE_THR		(sector_t)(8 * 1024)
-+#define BFQQ_SEEKY(bfqq)	(hweight32(bfqq->seek_history) > 32/8)
-+
-+/* Min number of samples required to perform peak-rate update */
-+#define BFQ_RATE_MIN_SAMPLES	32
-+/* Min observation time interval required to perform a peak-rate update (ns) */
-+#define BFQ_RATE_MIN_INTERVAL	(300*NSEC_PER_MSEC)
-+/* Target observation time interval for a peak-rate update (ns) */
-+#define BFQ_RATE_REF_INTERVAL	NSEC_PER_SEC
-+
-+/* Shift used for peak rate fixed precision calculations. */
-+#define BFQ_RATE_SHIFT		16
-+
-+/*
-+ * By default, BFQ computes the duration of the weight raising for
-+ * interactive applications automatically, using the following formula:
-+ * duration = (R / r) * T, where r is the peak rate of the device, and
-+ * R and T are two reference parameters.
-+ * In particular, R is the peak rate of the reference device (see below),
-+ * and T is a reference time: given the systems that are likely to be
-+ * installed on the reference device according to its speed class, T is
-+ * about the maximum time needed, under BFQ and while reading two files in
-+ * parallel, to load typical large applications on these systems.
-+ * In practice, the slower/faster the device at hand is, the more/less it
-+ * takes to load applications with respect to the reference device.
-+ * Accordingly, the longer/shorter BFQ grants weight raising to interactive
-+ * applications.
-+ *
-+ * BFQ uses four different reference pairs (R, T), depending on:
-+ * . whether the device is rotational or non-rotational;
-+ * . whether the device is slow, such as old or portable HDDs, as well as
-+ *   SD cards, or fast, such as newer HDDs and SSDs.
-+ *
-+ * The device's speed class is dynamically (re)detected in
-+ * bfq_update_peak_rate() every time the estimated peak rate is updated.
-+ *
-+ * In the following definitions, R_slow[0]/R_fast[0] and
-+ * T_slow[0]/T_fast[0] are the reference values for a slow/fast
-+ * rotational device, whereas R_slow[1]/R_fast[1] and
-+ * T_slow[1]/T_fast[1] are the reference values for a slow/fast
-+ * non-rotational device. Finally, device_speed_thresh are the
-+ * thresholds used to switch between speed classes. The reference
-+ * rates are not the actual peak rates of the devices used as a
-+ * reference, but slightly lower values. The reason for using these
-+ * slightly lower values is that the peak-rate estimator tends to
-+ * yield slightly lower values than the actual peak rate (it can yield
-+ * the actual peak rate only if there is only one process doing I/O,
-+ * and the process does sequential I/O).
-+ *
-+ * Both the reference peak rates and the thresholds are measured in
-+ * sectors/usec, left-shifted by BFQ_RATE_SHIFT.
-+ */
-+static int R_slow[2] = {1000, 10700};
-+static int R_fast[2] = {14000, 33000};
-+/*
-+ * To improve readability, a conversion function is used to initialize the
-+ * following arrays, which entails that they can be initialized only in a
-+ * function.
-+ */
-+static int T_slow[2];
-+static int T_fast[2];
-+static int device_speed_thresh[2];
-+
-+#define BFQ_SERVICE_TREE_INIT	((struct bfq_service_tree)		\
-+				{ RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 })
-+
-+#define RQ_BIC(rq)		((struct bfq_io_cq *) (rq)->elv.priv[0])
-+#define RQ_BFQQ(rq)		((rq)->elv.priv[1])
-+
-+static void bfq_schedule_dispatch(struct bfq_data *bfqd);
-+
-+#include "bfq-ioc.c"
-+#include "bfq-sched.c"
-+#include "bfq-cgroup-included.c"
-+
-+#define bfq_class_idle(bfqq)	((bfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
-+#define bfq_class_rt(bfqq)	((bfqq)->ioprio_class == IOPRIO_CLASS_RT)
-+
-+#define bfq_sample_valid(samples)	((samples) > 80)
-+
-+/*
-+ * Scheduler run of queue, if there are requests pending and no one in the
-+ * driver that will restart queueing.
-+ */
-+static void bfq_schedule_dispatch(struct bfq_data *bfqd)
-+{
-+	if (bfqd->queued != 0) {
-+		bfq_log(bfqd, "schedule dispatch");
-+		kblockd_schedule_work(&bfqd->unplug_work);
-+	}
-+}
-+
-+/*
-+ * Lifted from AS - choose which of rq1 and rq2 that is best served now.
-+ * We choose the request that is closesr to the head right now.  Distance
-+ * behind the head is penalized and only allowed to a certain extent.
-+ */
-+static struct request *bfq_choose_req(struct bfq_data *bfqd,
-+				      struct request *rq1,
-+				      struct request *rq2,
-+				      sector_t last)
-+{
-+	sector_t s1, s2, d1 = 0, d2 = 0;
-+	unsigned long back_max;
-+#define BFQ_RQ1_WRAP	0x01 /* request 1 wraps */
-+#define BFQ_RQ2_WRAP	0x02 /* request 2 wraps */
-+	unsigned int wrap = 0; /* bit mask: requests behind the disk head? */
-+
-+	if (!rq1 || rq1 == rq2)
-+		return rq2;
-+	if (!rq2)
-+		return rq1;
-+
-+	if (rq_is_sync(rq1) && !rq_is_sync(rq2))
-+		return rq1;
-+	else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
-+		return rq2;
-+	if ((rq1->cmd_flags & REQ_META) && !(rq2->cmd_flags & REQ_META))
-+		return rq1;
-+	else if ((rq2->cmd_flags & REQ_META) && !(rq1->cmd_flags & REQ_META))
-+		return rq2;
-+
-+	s1 = blk_rq_pos(rq1);
-+	s2 = blk_rq_pos(rq2);
-+
-+	/*
-+	 * By definition, 1KiB is 2 sectors.
-+	 */
-+	back_max = bfqd->bfq_back_max * 2;
-+
-+	/*
-+	 * Strict one way elevator _except_ in the case where we allow
-+	 * short backward seeks which are biased as twice the cost of a
-+	 * similar forward seek.
-+	 */
-+	if (s1 >= last)
-+		d1 = s1 - last;
-+	else if (s1 + back_max >= last)
-+		d1 = (last - s1) * bfqd->bfq_back_penalty;
-+	else
-+		wrap |= BFQ_RQ1_WRAP;
-+
-+	if (s2 >= last)
-+		d2 = s2 - last;
-+	else if (s2 + back_max >= last)
-+		d2 = (last - s2) * bfqd->bfq_back_penalty;
-+	else
-+		wrap |= BFQ_RQ2_WRAP;
-+
-+	/* Found required data */
-+
-+	/*
-+	 * By doing switch() on the bit mask "wrap" we avoid having to
-+	 * check two variables for all permutations: --> faster!
-+	 */
-+	switch (wrap) {
-+	case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
-+		if (d1 < d2)
-+			return rq1;
-+		else if (d2 < d1)
-+			return rq2;
-+
-+		if (s1 >= s2)
-+			return rq1;
-+		else
-+			return rq2;
-+
-+	case BFQ_RQ2_WRAP:
-+		return rq1;
-+	case BFQ_RQ1_WRAP:
-+		return rq2;
-+	case (BFQ_RQ1_WRAP|BFQ_RQ2_WRAP): /* both rqs wrapped */
-+	default:
-+		/*
-+		 * Since both rqs are wrapped,
-+		 * start with the one that's further behind head
-+		 * (--> only *one* back seek required),
-+		 * since back seek takes more time than forward.
-+		 */
-+		if (s1 <= s2)
-+			return rq1;
-+		else
-+			return rq2;
-+	}
-+}
-+
-+static struct bfq_queue *
-+bfq_rq_pos_tree_lookup(struct bfq_data *bfqd, struct rb_root *root,
-+		     sector_t sector, struct rb_node **ret_parent,
-+		     struct rb_node ***rb_link)
-+{
-+	struct rb_node **p, *parent;
-+	struct bfq_queue *bfqq = NULL;
-+
-+	parent = NULL;
-+	p = &root->rb_node;
-+	while (*p) {
-+		struct rb_node **n;
-+
-+		parent = *p;
-+		bfqq = rb_entry(parent, struct bfq_queue, pos_node);
-+
-+		/*
-+		 * Sort strictly based on sector. Smallest to the left,
-+		 * largest to the right.
-+		 */
-+		if (sector > blk_rq_pos(bfqq->next_rq))
-+			n = &(*p)->rb_right;
-+		else if (sector < blk_rq_pos(bfqq->next_rq))
-+			n = &(*p)->rb_left;
-+		else
-+			break;
-+		p = n;
-+		bfqq = NULL;
-+	}
-+
-+	*ret_parent = parent;
-+	if (rb_link)
-+		*rb_link = p;
-+
-+	bfq_log(bfqd, "rq_pos_tree_lookup %llu: returning %d",
-+		(unsigned long long) sector,
-+		bfqq ? bfqq->pid : 0);
-+
-+	return bfqq;
-+}
-+
-+static void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	struct rb_node **p, *parent;
-+	struct bfq_queue *__bfqq;
-+
-+	if (bfqq->pos_root) {
-+		rb_erase(&bfqq->pos_node, bfqq->pos_root);
-+		bfqq->pos_root = NULL;
-+	}
-+
-+	if (bfq_class_idle(bfqq))
-+		return;
-+	if (!bfqq->next_rq)
-+		return;
-+
-+	bfqq->pos_root = &bfq_bfqq_to_bfqg(bfqq)->rq_pos_tree;
-+	__bfqq = bfq_rq_pos_tree_lookup(bfqd, bfqq->pos_root,
-+			blk_rq_pos(bfqq->next_rq), &parent, &p);
-+	if (!__bfqq) {
-+		rb_link_node(&bfqq->pos_node, parent, p);
-+		rb_insert_color(&bfqq->pos_node, bfqq->pos_root);
-+	} else
-+		bfqq->pos_root = NULL;
-+}
-+
-+/*
-+ * Tell whether there are active queues or groups with differentiated weights.
-+ */
-+static bool bfq_differentiated_weights(struct bfq_data *bfqd)
-+{
-+	/*
-+	 * For weights to differ, at least one of the trees must contain
-+	 * at least two nodes.
-+	 */
-+	return (!RB_EMPTY_ROOT(&bfqd->queue_weights_tree) &&
-+		(bfqd->queue_weights_tree.rb_node->rb_left ||
-+		 bfqd->queue_weights_tree.rb_node->rb_right)
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	       ) ||
-+	       (!RB_EMPTY_ROOT(&bfqd->group_weights_tree) &&
-+		(bfqd->group_weights_tree.rb_node->rb_left ||
-+		 bfqd->group_weights_tree.rb_node->rb_right)
-+#endif
-+	       );
-+}
-+
-+/*
-+ * The following function returns true if every queue must receive the
-+ * same share of the throughput (this condition is used when deciding
-+ * whether idling may be disabled, see the comments in the function
-+ * bfq_bfqq_may_idle()).
-+ *
-+ * Such a scenario occurs when:
-+ * 1) all active queues have the same weight,
-+ * 2) all active groups at the same level in the groups tree have the same
-+ *    weight,
-+ * 3) all active groups at the same level in the groups tree have the same
-+ *    number of children.
-+ *
-+ * Unfortunately, keeping the necessary state for evaluating exactly the
-+ * above symmetry conditions would be quite complex and time-consuming.
-+ * Therefore this function evaluates, instead, the following stronger
-+ * sub-conditions, for which it is much easier to maintain the needed
-+ * state:
-+ * 1) all active queues have the same weight,
-+ * 2) all active groups have the same weight,
-+ * 3) all active groups have at most one active child each.
-+ * In particular, the last two conditions are always true if hierarchical
-+ * support and the cgroups interface are not enabled, thus no state needs
-+ * to be maintained in this case.
-+ */
-+static bool bfq_symmetric_scenario(struct bfq_data *bfqd)
-+{
-+	return !bfq_differentiated_weights(bfqd);
-+}
-+
-+/*
-+ * If the weight-counter tree passed as input contains no counter for
-+ * the weight of the input entity, then add that counter; otherwise just
-+ * increment the existing counter.
-+ *
-+ * Note that weight-counter trees contain few nodes in mostly symmetric
-+ * scenarios. For example, if all queues have the same weight, then the
-+ * weight-counter tree for the queues may contain at most one node.
-+ * This holds even if low_latency is on, because weight-raised queues
-+ * are not inserted in the tree.
-+ * In most scenarios, the rate at which nodes are created/destroyed
-+ * should be low too.
-+ */
-+static void bfq_weights_tree_add(struct bfq_data *bfqd,
-+				 struct bfq_entity *entity,
-+				 struct rb_root *root)
-+{
-+	struct rb_node **new = &(root->rb_node), *parent = NULL;
-+
-+	/*
-+	 * Do not insert if the entity is already associated with a
-+	 * counter, which happens if:
-+	 *   1) the entity is associated with a queue,
-+	 *   2) a request arrival has caused the queue to become both
-+	 *      non-weight-raised, and hence change its weight, and
-+	 *      backlogged; in this respect, each of the two events
-+	 *      causes an invocation of this function,
-+	 *   3) this is the invocation of this function caused by the
-+	 *      second event. This second invocation is actually useless,
-+	 *      and we handle this fact by exiting immediately. More
-+	 *      efficient or clearer solutions might possibly be adopted.
-+	 */
-+	if (entity->weight_counter)
-+		return;
-+
-+	while (*new) {
-+		struct bfq_weight_counter *__counter = container_of(*new,
-+						struct bfq_weight_counter,
-+						weights_node);
-+		parent = *new;
-+
-+		if (entity->weight == __counter->weight) {
-+			entity->weight_counter = __counter;
-+			goto inc_counter;
-+		}
-+		if (entity->weight < __counter->weight)
-+			new = &((*new)->rb_left);
-+		else
-+			new = &((*new)->rb_right);
-+	}
-+
-+	entity->weight_counter = kzalloc(sizeof(struct bfq_weight_counter),
-+					 GFP_ATOMIC);
-+
-+	/*
-+	 * In the unlucky event of an allocation failure, we just
-+	 * exit. This will cause the weight of entity to not be
-+	 * considered in bfq_differentiated_weights, which, in its
-+	 * turn, causes the scenario to be deemed wrongly symmetric in
-+	 * case entity's weight would have been the only weight making
-+	 * the scenario asymmetric. On the bright side, no unbalance
-+	 * will however occur when entity becomes inactive again (the
-+	 * invocation of this function is triggered by an activation
-+	 * of entity). In fact, bfq_weights_tree_remove does nothing
-+	 * if !entity->weight_counter.
-+	 */
-+	if (unlikely(!entity->weight_counter))
-+		return;
-+
-+	entity->weight_counter->weight = entity->weight;
-+	rb_link_node(&entity->weight_counter->weights_node, parent, new);
-+	rb_insert_color(&entity->weight_counter->weights_node, root);
-+
-+inc_counter:
-+	entity->weight_counter->num_active++;
-+}
-+
-+/*
-+ * Decrement the weight counter associated with the entity, and, if the
-+ * counter reaches 0, remove the counter from the tree.
-+ * See the comments to the function bfq_weights_tree_add() for considerations
-+ * about overhead.
-+ */
-+static void bfq_weights_tree_remove(struct bfq_data *bfqd,
-+				    struct bfq_entity *entity,
-+				    struct rb_root *root)
-+{
-+	if (!entity->weight_counter)
-+		return;
-+
-+	BUG_ON(RB_EMPTY_ROOT(root));
-+	BUG_ON(entity->weight_counter->weight != entity->weight);
-+
-+	BUG_ON(!entity->weight_counter->num_active);
-+	entity->weight_counter->num_active--;
-+	if (entity->weight_counter->num_active > 0)
-+		goto reset_entity_pointer;
-+
-+	rb_erase(&entity->weight_counter->weights_node, root);
-+	kfree(entity->weight_counter);
-+
-+reset_entity_pointer:
-+	entity->weight_counter = NULL;
-+}
-+
-+/*
-+ * Return expired entry, or NULL to just start from scratch in rbtree.
-+ */
-+static struct request *bfq_check_fifo(struct bfq_queue *bfqq,
-+				      struct request *last)
-+{
-+	struct request *rq;
-+
-+	if (bfq_bfqq_fifo_expire(bfqq))
-+		return NULL;
-+
-+	bfq_mark_bfqq_fifo_expire(bfqq);
-+
-+	rq = rq_entry_fifo(bfqq->fifo.next);
-+
-+	if (rq == last || ktime_get_ns() < rq->fifo_time)
-+		return NULL;
-+
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "check_fifo: returned %p", rq);
-+	BUG_ON(RB_EMPTY_NODE(&rq->rb_node));
-+	return rq;
-+}
-+
-+static struct request *bfq_find_next_rq(struct bfq_data *bfqd,
-+					struct bfq_queue *bfqq,
-+					struct request *last)
-+{
-+	struct rb_node *rbnext = rb_next(&last->rb_node);
-+	struct rb_node *rbprev = rb_prev(&last->rb_node);
-+	struct request *next, *prev = NULL;
-+
-+	BUG_ON(list_empty(&bfqq->fifo));
-+
-+	/* Follow expired path, else get first next available. */
-+	next = bfq_check_fifo(bfqq, last);
-+	if (next) {
-+		BUG_ON(next == last);
-+		return next;
-+	}
-+
-+	BUG_ON(RB_EMPTY_NODE(&last->rb_node));
-+
-+	if (rbprev)
-+		prev = rb_entry_rq(rbprev);
-+
-+	if (rbnext)
-+		next = rb_entry_rq(rbnext);
-+	else {
-+		rbnext = rb_first(&bfqq->sort_list);
-+		if (rbnext && rbnext != &last->rb_node)
-+			next = rb_entry_rq(rbnext);
-+	}
-+
-+	return bfq_choose_req(bfqd, next, prev, blk_rq_pos(last));
-+}
-+
-+/* see the definition of bfq_async_charge_factor for details */
-+static unsigned long bfq_serv_to_charge(struct request *rq,
-+					struct bfq_queue *bfqq)
-+{
-+	if (bfq_bfqq_sync(bfqq) || bfqq->wr_coeff > 1)
-+		return blk_rq_sectors(rq);
-+
-+	/*
-+	 * If there are no weight-raised queues, then amplify service
-+	 * by just the async charge factor; otherwise amplify service
-+	 * by twice the async charge factor, to further reduce latency
-+	 * for weight-raised queues.
-+	 */
-+	if (bfqq->bfqd->wr_busy_queues == 0)
-+		return blk_rq_sectors(rq) * bfq_async_charge_factor;
-+
-+	return blk_rq_sectors(rq) * 2 * bfq_async_charge_factor;
-+}
-+
-+/**
-+ * bfq_updated_next_req - update the queue after a new next_rq selection.
-+ * @bfqd: the device data the queue belongs to.
-+ * @bfqq: the queue to update.
-+ *
-+ * If the first request of a queue changes we make sure that the queue
-+ * has enough budget to serve at least its first request (if the
-+ * request has grown).  We do this because if the queue has not enough
-+ * budget for its first request, it has to go through two dispatch
-+ * rounds to actually get it dispatched.
-+ */
-+static void bfq_updated_next_req(struct bfq_data *bfqd,
-+				 struct bfq_queue *bfqq)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+	struct bfq_service_tree *st = bfq_entity_service_tree(entity);
-+	struct request *next_rq = bfqq->next_rq;
-+	unsigned long new_budget;
-+
-+	if (!next_rq)
-+		return;
-+
-+	if (bfqq == bfqd->in_service_queue)
-+		/*
-+		 * In order not to break guarantees, budgets cannot be
-+		 * changed after an entity has been selected.
-+		 */
-+		return;
-+
-+	BUG_ON(entity->tree != &st->active);
-+	BUG_ON(entity == entity->sched_data->in_service_entity);
-+
-+	new_budget = max_t(unsigned long, bfqq->max_budget,
-+			   bfq_serv_to_charge(next_rq, bfqq));
-+	if (entity->budget != new_budget) {
-+		entity->budget = new_budget;
-+		bfq_log_bfqq(bfqd, bfqq, "updated next rq: new budget %lu",
-+					 new_budget);
-+		bfq_requeue_bfqq(bfqd, bfqq);
-+	}
-+}
-+
-+static unsigned int bfq_wr_duration(struct bfq_data *bfqd)
-+{
-+	u64 dur;
-+
-+	if (bfqd->bfq_wr_max_time > 0)
-+		return bfqd->bfq_wr_max_time;
-+
-+	dur = bfqd->RT_prod;
-+	do_div(dur, bfqd->peak_rate);
-+
-+	/*
-+	 * Limit duration between 3 and 13 seconds. Tests show that
-+	 * higher values than 13 seconds often yield the opposite of
-+	 * the desired result, i.e., worsen responsiveness by letting
-+	 * non-interactive and non-soft-real-time applications
-+	 * preserve weight raising for a too long time interval.
-+	 *
-+	 * On the other end, lower values than 3 seconds make it
-+	 * difficult for most interactive tasks to complete their jobs
-+	 * before weight-raising finishes.
-+	 */
-+	if (dur > msecs_to_jiffies(13000))
-+		dur = msecs_to_jiffies(13000);
-+	else if (dur < msecs_to_jiffies(3000))
-+		dur = msecs_to_jiffies(3000);
-+
-+	return dur;
-+}
-+
-+static void
-+bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_data *bfqd,
-+		      struct bfq_io_cq *bic, bool bfq_already_existing)
-+{
-+	unsigned int old_wr_coeff;
-+	bool busy = bfq_already_existing && bfq_bfqq_busy(bfqq);
-+
-+	if (bic->saved_has_short_ttime)
-+		bfq_mark_bfqq_has_short_ttime(bfqq);
-+	else
-+		bfq_clear_bfqq_has_short_ttime(bfqq);
-+
-+	if (bic->saved_IO_bound)
-+		bfq_mark_bfqq_IO_bound(bfqq);
-+	else
-+		bfq_clear_bfqq_IO_bound(bfqq);
-+
-+	if (unlikely(busy))
-+		old_wr_coeff = bfqq->wr_coeff;
-+
-+	bfqq->wr_coeff = bic->saved_wr_coeff;
-+	bfqq->wr_start_at_switch_to_srt = bic->saved_wr_start_at_switch_to_srt;
-+	BUG_ON(time_is_after_jiffies(bfqq->wr_start_at_switch_to_srt));
-+	bfqq->last_wr_start_finish = bic->saved_last_wr_start_finish;
-+	bfqq->wr_cur_max_time = bic->saved_wr_cur_max_time;
-+	BUG_ON(time_is_after_jiffies(bfqq->last_wr_start_finish));
-+
-+	if (bfqq->wr_coeff > 1 && (bfq_bfqq_in_large_burst(bfqq) ||
-+				   time_is_before_jiffies(bfqq->last_wr_start_finish +
-+							  bfqq->wr_cur_max_time))) {
-+		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			     "resume state: switching off wr (%lu + %lu < %lu)",
-+			     bfqq->last_wr_start_finish, bfqq->wr_cur_max_time,
-+			     jiffies);
-+
-+		bfqq->wr_coeff = 1;
-+	}
-+
-+	/* make sure weight will be updated, however we got here */
-+	bfqq->entity.prio_changed = 1;
-+
-+	if (likely(!busy))
-+		return;
-+
-+	if (old_wr_coeff == 1 && bfqq->wr_coeff > 1) {
-+		bfqd->wr_busy_queues++;
-+		BUG_ON(bfqd->wr_busy_queues > bfqd->busy_queues);
-+	} else if (old_wr_coeff > 1 && bfqq->wr_coeff == 1) {
-+		bfqd->wr_busy_queues--;
-+		BUG_ON(bfqd->wr_busy_queues < 0);
-+	}
-+}
-+
-+static int bfqq_process_refs(struct bfq_queue *bfqq)
-+{
-+	int process_refs, io_refs;
-+
-+	lockdep_assert_held(bfqq->bfqd->queue->queue_lock);
-+
-+	io_refs = bfqq->allocated[READ] + bfqq->allocated[WRITE];
-+	process_refs = bfqq->ref - io_refs - bfqq->entity.on_st;
-+	BUG_ON(process_refs < 0);
-+	return process_refs;
-+}
-+
-+/* Empty burst list and add just bfqq (see comments to bfq_handle_burst) */
-+static void bfq_reset_burst_list(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	struct bfq_queue *item;
-+	struct hlist_node *n;
-+
-+	hlist_for_each_entry_safe(item, n, &bfqd->burst_list, burst_list_node)
-+		hlist_del_init(&item->burst_list_node);
-+	hlist_add_head(&bfqq->burst_list_node, &bfqd->burst_list);
-+	bfqd->burst_size = 1;
-+	bfqd->burst_parent_entity = bfqq->entity.parent;
-+}
-+
-+/* Add bfqq to the list of queues in current burst (see bfq_handle_burst) */
-+static void bfq_add_to_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	/* Increment burst size to take into account also bfqq */
-+	bfqd->burst_size++;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "add_to_burst %d", bfqd->burst_size);
-+
-+	BUG_ON(bfqd->burst_size > bfqd->bfq_large_burst_thresh);
-+
-+	if (bfqd->burst_size == bfqd->bfq_large_burst_thresh) {
-+		struct bfq_queue *pos, *bfqq_item;
-+		struct hlist_node *n;
-+
-+		/*
-+		 * Enough queues have been activated shortly after each
-+		 * other to consider this burst as large.
-+		 */
-+		bfqd->large_burst = true;
-+		bfq_log_bfqq(bfqd, bfqq, "add_to_burst: large burst started");
-+
-+		/*
-+		 * We can now mark all queues in the burst list as
-+		 * belonging to a large burst.
-+		 */
-+		hlist_for_each_entry(bfqq_item, &bfqd->burst_list,
-+				     burst_list_node) {
-+			bfq_mark_bfqq_in_large_burst(bfqq_item);
-+			bfq_log_bfqq(bfqd, bfqq_item, "marked in large burst");
-+		}
-+		bfq_mark_bfqq_in_large_burst(bfqq);
-+		bfq_log_bfqq(bfqd, bfqq, "marked in large burst");
-+
-+		/*
-+		 * From now on, and until the current burst finishes, any
-+		 * new queue being activated shortly after the last queue
-+		 * was inserted in the burst can be immediately marked as
-+		 * belonging to a large burst. So the burst list is not
-+		 * needed any more. Remove it.
-+		 */
-+		hlist_for_each_entry_safe(pos, n, &bfqd->burst_list,
-+					  burst_list_node)
-+			hlist_del_init(&pos->burst_list_node);
-+	} else /*
-+		* Burst not yet large: add bfqq to the burst list. Do
-+		* not increment the ref counter for bfqq, because bfqq
-+		* is removed from the burst list before freeing bfqq
-+		* in put_queue.
-+		*/
-+		hlist_add_head(&bfqq->burst_list_node, &bfqd->burst_list);
-+}
-+
-+/*
-+ * If many queues belonging to the same group happen to be created
-+ * shortly after each other, then the processes associated with these
-+ * queues have typically a common goal. In particular, bursts of queue
-+ * creations are usually caused by services or applications that spawn
-+ * many parallel threads/processes. Examples are systemd during boot,
-+ * or git grep. To help these processes get their job done as soon as
-+ * possible, it is usually better to not grant either weight-raising
-+ * or device idling to their queues.
-+ *
-+ * In this comment we describe, firstly, the reasons why this fact
-+ * holds, and, secondly, the next function, which implements the main
-+ * steps needed to properly mark these queues so that they can then be
-+ * treated in a different way.
-+ *
-+ * The above services or applications benefit mostly from a high
-+ * throughput: the quicker the requests of the activated queues are
-+ * cumulatively served, the sooner the target job of these queues gets
-+ * completed. As a consequence, weight-raising any of these queues,
-+ * which also implies idling the device for it, is almost always
-+ * counterproductive. In most cases it just lowers throughput.
-+ *
-+ * On the other hand, a burst of queue creations may be caused also by
-+ * the start of an application that does not consist of a lot of
-+ * parallel I/O-bound threads. In fact, with a complex application,
-+ * several short processes may need to be executed to start-up the
-+ * application. In this respect, to start an application as quickly as
-+ * possible, the best thing to do is in any case to privilege the I/O
-+ * related to the application with respect to all other
-+ * I/O. Therefore, the best strategy to start as quickly as possible
-+ * an application that causes a burst of queue creations is to
-+ * weight-raise all the queues created during the burst. This is the
-+ * exact opposite of the best strategy for the other type of bursts.
-+ *
-+ * In the end, to take the best action for each of the two cases, the
-+ * two types of bursts need to be distinguished. Fortunately, this
-+ * seems relatively easy, by looking at the sizes of the bursts. In
-+ * particular, we found a threshold such that only bursts with a
-+ * larger size than that threshold are apparently caused by
-+ * services or commands such as systemd or git grep. For brevity,
-+ * hereafter we call just 'large' these bursts. BFQ *does not*
-+ * weight-raise queues whose creation occurs in a large burst. In
-+ * addition, for each of these queues BFQ performs or does not perform
-+ * idling depending on which choice boosts the throughput more. The
-+ * exact choice depends on the device and request pattern at
-+ * hand.
-+ *
-+ * Unfortunately, false positives may occur while an interactive task
-+ * is starting (e.g., an application is being started). The
-+ * consequence is that the queues associated with the task do not
-+ * enjoy weight raising as expected. Fortunately these false positives
-+ * are very rare. They typically occur if some service happens to
-+ * start doing I/O exactly when the interactive task starts.
-+ *
-+ * Turning back to the next function, it implements all the steps
-+ * needed to detect the occurrence of a large burst and to properly
-+ * mark all the queues belonging to it (so that they can then be
-+ * treated in a different way). This goal is achieved by maintaining a
-+ * "burst list" that holds, temporarily, the queues that belong to the
-+ * burst in progress. The list is then used to mark these queues as
-+ * belonging to a large burst if the burst does become large. The main
-+ * steps are the following.
-+ *
-+ * . when the very first queue is created, the queue is inserted into the
-+ *   list (as it could be the first queue in a possible burst)
-+ *
-+ * . if the current burst has not yet become large, and a queue Q that does
-+ *   not yet belong to the burst is activated shortly after the last time
-+ *   at which a new queue entered the burst list, then the function appends
-+ *   Q to the burst list
-+ *
-+ * . if, as a consequence of the previous step, the burst size reaches
-+ *   the large-burst threshold, then
-+ *
-+ *     . all the queues in the burst list are marked as belonging to a
-+ *       large burst
-+ *
-+ *     . the burst list is deleted; in fact, the burst list already served
-+ *       its purpose (keeping temporarily track of the queues in a burst,
-+ *       so as to be able to mark them as belonging to a large burst in the
-+ *       previous sub-step), and now is not needed any more
-+ *
-+ *     . the device enters a large-burst mode
-+ *
-+ * . if a queue Q that does not belong to the burst is created while
-+ *   the device is in large-burst mode and shortly after the last time
-+ *   at which a queue either entered the burst list or was marked as
-+ *   belonging to the current large burst, then Q is immediately marked
-+ *   as belonging to a large burst.
-+ *
-+ * . if a queue Q that does not belong to the burst is created a while
-+ *   later, i.e., not shortly after, than the last time at which a queue
-+ *   either entered the burst list or was marked as belonging to the
-+ *   current large burst, then the current burst is deemed as finished and:
-+ *
-+ *        . the large-burst mode is reset if set
-+ *
-+ *        . the burst list is emptied
-+ *
-+ *        . Q is inserted in the burst list, as Q may be the first queue
-+ *          in a possible new burst (then the burst list contains just Q
-+ *          after this step).
-+ */
-+static void bfq_handle_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	/*
-+	 * If bfqq is already in the burst list or is part of a large
-+	 * burst, or finally has just been split, then there is
-+	 * nothing else to do.
-+	 */
-+	if (!hlist_unhashed(&bfqq->burst_list_node) ||
-+	    bfq_bfqq_in_large_burst(bfqq) ||
-+	    time_is_after_eq_jiffies(bfqq->split_time +
-+				     msecs_to_jiffies(10)))
-+		return;
-+
-+	/*
-+	 * If bfqq's creation happens late enough, or bfqq belongs to
-+	 * a different group than the burst group, then the current
-+	 * burst is finished, and related data structures must be
-+	 * reset.
-+	 *
-+	 * In this respect, consider the special case where bfqq is
-+	 * the very first queue created after BFQ is selected for this
-+	 * device. In this case, last_ins_in_burst and
-+	 * burst_parent_entity are not yet significant when we get
-+	 * here. But it is easy to verify that, whether or not the
-+	 * following condition is true, bfqq will end up being
-+	 * inserted into the burst list. In particular the list will
-+	 * happen to contain only bfqq. And this is exactly what has
-+	 * to happen, as bfqq may be the first queue of the first
-+	 * burst.
-+	 */
-+	if (time_is_before_jiffies(bfqd->last_ins_in_burst +
-+	    bfqd->bfq_burst_interval) ||
-+	    bfqq->entity.parent != bfqd->burst_parent_entity) {
-+		bfqd->large_burst = false;
-+		bfq_reset_burst_list(bfqd, bfqq);
-+		bfq_log_bfqq(bfqd, bfqq,
-+			"handle_burst: late activation or different group");
-+		goto end;
-+	}
-+
-+	/*
-+	 * If we get here, then bfqq is being activated shortly after the
-+	 * last queue. So, if the current burst is also large, we can mark
-+	 * bfqq as belonging to this large burst immediately.
-+	 */
-+	if (bfqd->large_burst) {
-+		bfq_log_bfqq(bfqd, bfqq, "handle_burst: marked in burst");
-+		bfq_mark_bfqq_in_large_burst(bfqq);
-+		goto end;
-+	}
-+
-+	/*
-+	 * If we get here, then a large-burst state has not yet been
-+	 * reached, but bfqq is being activated shortly after the last
-+	 * queue. Then we add bfqq to the burst.
-+	 */
-+	bfq_add_to_burst(bfqd, bfqq);
-+end:
-+	/*
-+	 * At this point, bfqq either has been added to the current
-+	 * burst or has caused the current burst to terminate and a
-+	 * possible new burst to start. In particular, in the second
-+	 * case, bfqq has become the first queue in the possible new
-+	 * burst.  In both cases last_ins_in_burst needs to be moved
-+	 * forward.
-+	 */
-+	bfqd->last_ins_in_burst = jiffies;
-+
-+}
-+
-+static int bfq_bfqq_budget_left(struct bfq_queue *bfqq)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+
-+	return entity->budget - entity->service;
-+}
-+
-+/*
-+ * If enough samples have been computed, return the current max budget
-+ * stored in bfqd, which is dynamically updated according to the
-+ * estimated disk peak rate; otherwise return the default max budget
-+ */
-+static int bfq_max_budget(struct bfq_data *bfqd)
-+{
-+	if (bfqd->budgets_assigned < bfq_stats_min_budgets)
-+		return bfq_default_max_budget;
-+	else
-+		return bfqd->bfq_max_budget;
-+}
-+
-+/*
-+ * Return min budget, which is a fraction of the current or default
-+ * max budget (trying with 1/32)
-+ */
-+static int bfq_min_budget(struct bfq_data *bfqd)
-+{
-+	if (bfqd->budgets_assigned < bfq_stats_min_budgets)
-+		return bfq_default_max_budget / 32;
-+	else
-+		return bfqd->bfq_max_budget / 32;
-+}
-+
-+static void bfq_bfqq_expire(struct bfq_data *bfqd,
-+			    struct bfq_queue *bfqq,
-+			    bool compensate,
-+			    enum bfqq_expiration reason);
-+
-+/*
-+ * The next function, invoked after the input queue bfqq switches from
-+ * idle to busy, updates the budget of bfqq. The function also tells
-+ * whether the in-service queue should be expired, by returning
-+ * true. The purpose of expiring the in-service queue is to give bfqq
-+ * the chance to possibly preempt the in-service queue, and the reason
-+ * for preempting the in-service queue is to achieve one of the two
-+ * goals below.
-+ *
-+ * 1. Guarantee to bfqq its reserved bandwidth even if bfqq has
-+ * expired because it has remained idle. In particular, bfqq may have
-+ * expired for one of the following two reasons:
-+ *
-+ * - BFQ_BFQQ_NO_MORE_REQUEST bfqq did not enjoy any device idling and
-+ *   did not make it to issue a new request before its last request
-+ *   was served;
-+ *
-+ * - BFQ_BFQQ_TOO_IDLE bfqq did enjoy device idling, but did not issue
-+ *   a new request before the expiration of the idling-time.
-+ *
-+ * Even if bfqq has expired for one of the above reasons, the process
-+ * associated with the queue may be however issuing requests greedily,
-+ * and thus be sensitive to the bandwidth it receives (bfqq may have
-+ * remained idle for other reasons: CPU high load, bfqq not enjoying
-+ * idling, I/O throttling somewhere in the path from the process to
-+ * the I/O scheduler, ...). But if, after every expiration for one of
-+ * the above two reasons, bfqq has to wait for the service of at least
-+ * one full budget of another queue before being served again, then
-+ * bfqq is likely to get a much lower bandwidth or resource time than
-+ * its reserved ones. To address this issue, two countermeasures need
-+ * to be taken.
-+ *
-+ * First, the budget and the timestamps of bfqq need to be updated in
-+ * a special way on bfqq reactivation: they need to be updated as if
-+ * bfqq did not remain idle and did not expire. In fact, if they are
-+ * computed as if bfqq expired and remained idle until reactivation,
-+ * then the process associated with bfqq is treated as if, instead of
-+ * being greedy, it stopped issuing requests when bfqq remained idle,
-+ * and restarts issuing requests only on this reactivation. In other
-+ * words, the scheduler does not help the process recover the "service
-+ * hole" between bfqq expiration and reactivation. As a consequence,
-+ * the process receives a lower bandwidth than its reserved one. In
-+ * contrast, to recover this hole, the budget must be updated as if
-+ * bfqq was not expired at all before this reactivation, i.e., it must
-+ * be set to the value of the remaining budget when bfqq was
-+ * expired. Along the same line, timestamps need to be assigned the
-+ * value they had the last time bfqq was selected for service, i.e.,
-+ * before last expiration. Thus timestamps need to be back-shifted
-+ * with respect to their normal computation (see [1] for more details
-+ * on this tricky aspect).
-+ *
-+ * Secondly, to allow the process to recover the hole, the in-service
-+ * queue must be expired too, to give bfqq the chance to preempt it
-+ * immediately. In fact, if bfqq has to wait for a full budget of the
-+ * in-service queue to be completed, then it may become impossible to
-+ * let the process recover the hole, even if the back-shifted
-+ * timestamps of bfqq are lower than those of the in-service queue. If
-+ * this happens for most or all of the holes, then the process may not
-+ * receive its reserved bandwidth. In this respect, it is worth noting
-+ * that, being the service of outstanding requests unpreemptible, a
-+ * little fraction of the holes may however be unrecoverable, thereby
-+ * causing a little loss of bandwidth.
-+ *
-+ * The last important point is detecting whether bfqq does need this
-+ * bandwidth recovery. In this respect, the next function deems the
-+ * process associated with bfqq greedy, and thus allows it to recover
-+ * the hole, if: 1) the process is waiting for the arrival of a new
-+ * request (which implies that bfqq expired for one of the above two
-+ * reasons), and 2) such a request has arrived soon. The first
-+ * condition is controlled through the flag non_blocking_wait_rq,
-+ * while the second through the flag arrived_in_time. If both
-+ * conditions hold, then the function computes the budget in the
-+ * above-described special way, and signals that the in-service queue
-+ * should be expired. Timestamp back-shifting is done later in
-+ * __bfq_activate_entity.
-+ *
-+ * 2. Reduce latency. Even if timestamps are not backshifted to let
-+ * the process associated with bfqq recover a service hole, bfqq may
-+ * however happen to have, after being (re)activated, a lower finish
-+ * timestamp than the in-service queue.  That is, the next budget of
-+ * bfqq may have to be completed before the one of the in-service
-+ * queue. If this is the case, then preempting the in-service queue
-+ * allows this goal to be achieved, apart from the unpreemptible,
-+ * outstanding requests mentioned above.
-+ *
-+ * Unfortunately, regardless of which of the above two goals one wants
-+ * to achieve, service trees need first to be updated to know whether
-+ * the in-service queue must be preempted. To have service trees
-+ * correctly updated, the in-service queue must be expired and
-+ * rescheduled, and bfqq must be scheduled too. This is one of the
-+ * most costly operations (in future versions, the scheduling
-+ * mechanism may be re-designed in such a way to make it possible to
-+ * know whether preemption is needed without needing to update service
-+ * trees). In addition, queue preemptions almost always cause random
-+ * I/O, and thus loss of throughput. Because of these facts, the next
-+ * function adopts the following simple scheme to avoid both costly
-+ * operations and too frequent preemptions: it requests the expiration
-+ * of the in-service queue (unconditionally) only for queues that need
-+ * to recover a hole, or that either are weight-raised or deserve to
-+ * be weight-raised.
-+ */
-+static bool bfq_bfqq_update_budg_for_activation(struct bfq_data *bfqd,
-+						struct bfq_queue *bfqq,
-+						bool arrived_in_time,
-+						bool wr_or_deserves_wr)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+
-+	if (bfq_bfqq_non_blocking_wait_rq(bfqq) && arrived_in_time) {
-+		/*
-+		 * We do not clear the flag non_blocking_wait_rq here, as
-+		 * the latter is used in bfq_activate_bfqq to signal
-+		 * that timestamps need to be back-shifted (and is
-+		 * cleared right after).
-+		 */
-+
-+		/*
-+		 * In next assignment we rely on that either
-+		 * entity->service or entity->budget are not updated
-+		 * on expiration if bfqq is empty (see
-+		 * __bfq_bfqq_recalc_budget). Thus both quantities
-+		 * remain unchanged after such an expiration, and the
-+		 * following statement therefore assigns to
-+		 * entity->budget the remaining budget on such an
-+		 * expiration. For clarity, entity->service is not
-+		 * updated on expiration in any case, and, in normal
-+		 * operation, is reset only when bfqq is selected for
-+		 * service (see bfq_get_next_queue).
-+		 */
-+		BUG_ON(bfqq->max_budget < 0);
-+		entity->budget = min_t(unsigned long,
-+				       bfq_bfqq_budget_left(bfqq),
-+				       bfqq->max_budget);
-+
-+		BUG_ON(entity->budget < 0);
-+		return true;
-+	}
-+
-+	BUG_ON(bfqq->max_budget < 0);
-+	entity->budget = max_t(unsigned long, bfqq->max_budget,
-+			       bfq_serv_to_charge(bfqq->next_rq, bfqq));
-+	BUG_ON(entity->budget < 0);
-+
-+	bfq_clear_bfqq_non_blocking_wait_rq(bfqq);
-+	return wr_or_deserves_wr;
-+}
-+
-+static void bfq_update_bfqq_wr_on_rq_arrival(struct bfq_data *bfqd,
-+					     struct bfq_queue *bfqq,
-+					     unsigned int old_wr_coeff,
-+					     bool wr_or_deserves_wr,
-+					     bool interactive,
-+					     bool in_burst,
-+					     bool soft_rt)
-+{
-+	if (old_wr_coeff == 1 && wr_or_deserves_wr) {
-+		/* start a weight-raising period */
-+		if (interactive) {
-+			bfqq->wr_coeff = bfqd->bfq_wr_coeff;
-+			bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
-+		} else {
-+			bfqq->wr_start_at_switch_to_srt = jiffies;
-+			bfqq->wr_coeff = bfqd->bfq_wr_coeff *
-+				BFQ_SOFTRT_WEIGHT_FACTOR;
-+			bfqq->wr_cur_max_time =
-+				bfqd->bfq_wr_rt_max_time;
-+		}
-+		/*
-+		 * If needed, further reduce budget to make sure it is
-+		 * close to bfqq's backlog, so as to reduce the
-+		 * scheduling-error component due to a too large
-+		 * budget. Do not care about throughput consequences,
-+		 * but only about latency. Finally, do not assign a
-+		 * too small budget either, to avoid increasing
-+		 * latency by causing too frequent expirations.
-+		 */
-+		bfqq->entity.budget = min_t(unsigned long,
-+					    bfqq->entity.budget,
-+					    2 * bfq_min_budget(bfqd));
-+
-+		bfq_log_bfqq(bfqd, bfqq,
-+			     "wrais starting at %lu, rais_max_time %u",
-+			     jiffies,
-+			     jiffies_to_msecs(bfqq->wr_cur_max_time));
-+	} else if (old_wr_coeff > 1) {
-+		if (interactive) { /* update wr coeff and duration */
-+			bfqq->wr_coeff = bfqd->bfq_wr_coeff;
-+			bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
-+		} else if (in_burst) {
-+			bfqq->wr_coeff = 1;
-+			bfq_log_bfqq(bfqd, bfqq,
-+				     "wrais ending at %lu, rais_max_time %u",
-+				     jiffies,
-+				     jiffies_to_msecs(bfqq->
-+						      wr_cur_max_time));
-+		} else if (soft_rt) {
-+			/*
-+			 * The application is now or still meeting the
-+			 * requirements for being deemed soft rt.  We
-+			 * can then correctly and safely (re)charge
-+			 * the weight-raising duration for the
-+			 * application with the weight-raising
-+			 * duration for soft rt applications.
-+			 *
-+			 * In particular, doing this recharge now, i.e.,
-+			 * before the weight-raising period for the
-+			 * application finishes, reduces the probability
-+			 * of the following negative scenario:
-+			 * 1) the weight of a soft rt application is
-+			 *    raised at startup (as for any newly
-+			 *    created application),
-+			 * 2) since the application is not interactive,
-+			 *    at a certain time weight-raising is
-+			 *    stopped for the application,
-+			 * 3) at that time the application happens to
-+			 *    still have pending requests, and hence
-+			 *    is destined to not have a chance to be
-+			 *    deemed soft rt before these requests are
-+			 *    completed (see the comments to the
-+			 *    function bfq_bfqq_softrt_next_start()
-+			 *    for details on soft rt detection),
-+			 * 4) these pending requests experience a high
-+			 *    latency because the application is not
-+			 *    weight-raised while they are pending.
-+			 */
-+			if (bfqq->wr_cur_max_time !=
-+				bfqd->bfq_wr_rt_max_time) {
-+				bfqq->wr_start_at_switch_to_srt =
-+					bfqq->last_wr_start_finish;
-+                BUG_ON(time_is_after_jiffies(bfqq->last_wr_start_finish));
-+
-+				bfqq->wr_cur_max_time =
-+					bfqd->bfq_wr_rt_max_time;
-+				bfqq->wr_coeff = bfqd->bfq_wr_coeff *
-+					BFQ_SOFTRT_WEIGHT_FACTOR;
-+				bfq_log_bfqq(bfqd, bfqq,
-+					     "switching to soft_rt wr");
-+			} else
-+				bfq_log_bfqq(bfqd, bfqq,
-+					"moving forward soft_rt wr duration");
-+			bfqq->last_wr_start_finish = jiffies;
-+		}
-+	}
-+}
-+
-+static bool bfq_bfqq_idle_for_long_time(struct bfq_data *bfqd,
-+					struct bfq_queue *bfqq)
-+{
-+	return bfqq->dispatched == 0 &&
-+		time_is_before_jiffies(
-+			bfqq->budget_timeout +
-+			bfqd->bfq_wr_min_idle_time);
-+}
-+
-+static void bfq_bfqq_handle_idle_busy_switch(struct bfq_data *bfqd,
-+					     struct bfq_queue *bfqq,
-+					     int old_wr_coeff,
-+					     struct request *rq,
-+					     bool *interactive)
-+{
-+	bool soft_rt, in_burst,	wr_or_deserves_wr,
-+		bfqq_wants_to_preempt,
-+		idle_for_long_time = bfq_bfqq_idle_for_long_time(bfqd, bfqq),
-+		/*
-+		 * See the comments on
-+		 * bfq_bfqq_update_budg_for_activation for
-+		 * details on the usage of the next variable.
-+		 */
-+		arrived_in_time =  ktime_get_ns() <=
-+			RQ_BIC(rq)->ttime.last_end_request +
-+			bfqd->bfq_slice_idle * 3;
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+		     "bfq_add_request non-busy: "
-+		     "jiffies %lu, in_time %d, idle_long %d busyw %d "
-+		     "wr_coeff %u",
-+		     jiffies, arrived_in_time,
-+		     idle_for_long_time,
-+		     bfq_bfqq_non_blocking_wait_rq(bfqq),
-+		     old_wr_coeff);
-+
-+	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
-+
-+	BUG_ON(bfqq == bfqd->in_service_queue);
-+	bfqg_stats_update_io_add(bfqq_group(RQ_BFQQ(rq)), bfqq, rq->cmd_flags);
-+
-+	/*
-+	 * bfqq deserves to be weight-raised if:
-+	 * - it is sync,
-+	 * - it does not belong to a large burst,
-+	 * - it has been idle for enough time or is soft real-time,
-+	 * - is linked to a bfq_io_cq (it is not shared in any sense)
-+	 */
-+	in_burst = bfq_bfqq_in_large_burst(bfqq);
-+	soft_rt = bfqd->bfq_wr_max_softrt_rate > 0 &&
-+		!in_burst &&
-+		time_is_before_jiffies(bfqq->soft_rt_next_start);
-+	*interactive =
-+		!in_burst &&
-+		idle_for_long_time;
-+	wr_or_deserves_wr = bfqd->low_latency &&
-+		(bfqq->wr_coeff > 1 ||
-+		 (bfq_bfqq_sync(bfqq) &&
-+		  bfqq->bic && (*interactive || soft_rt)));
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+		     "bfq_add_request: "
-+		     "in_burst %d, "
-+		     "soft_rt %d (next %lu), inter %d, bic %p",
-+		     bfq_bfqq_in_large_burst(bfqq), soft_rt,
-+		     bfqq->soft_rt_next_start,
-+		     *interactive,
-+		     bfqq->bic);
-+
-+	/*
-+	 * Using the last flag, update budget and check whether bfqq
-+	 * may want to preempt the in-service queue.
-+	 */
-+	bfqq_wants_to_preempt =
-+		bfq_bfqq_update_budg_for_activation(bfqd, bfqq,
-+						    arrived_in_time,
-+						    wr_or_deserves_wr);
-+
-+	/*
-+	 * If bfqq happened to be activated in a burst, but has been
-+	 * idle for much more than an interactive queue, then we
-+	 * assume that, in the overall I/O initiated in the burst, the
-+	 * I/O associated with bfqq is finished. So bfqq does not need
-+	 * to be treated as a queue belonging to a burst
-+	 * anymore. Accordingly, we reset bfqq's in_large_burst flag
-+	 * if set, and remove bfqq from the burst list if it's
-+	 * there. We do not decrement burst_size, because the fact
-+	 * that bfqq does not need to belong to the burst list any
-+	 * more does not invalidate the fact that bfqq was created in
-+	 * a burst.
-+	 */
-+	if (likely(!bfq_bfqq_just_created(bfqq)) &&
-+	    idle_for_long_time &&
-+	    time_is_before_jiffies(
-+		    bfqq->budget_timeout +
-+		    msecs_to_jiffies(10000))) {
-+		hlist_del_init(&bfqq->burst_list_node);
-+		bfq_clear_bfqq_in_large_burst(bfqq);
-+	}
-+
-+	bfq_clear_bfqq_just_created(bfqq);
-+
-+	if (!bfq_bfqq_IO_bound(bfqq)) {
-+		if (arrived_in_time) {
-+			bfqq->requests_within_timer++;
-+			if (bfqq->requests_within_timer >=
-+			    bfqd->bfq_requests_within_timer)
-+				bfq_mark_bfqq_IO_bound(bfqq);
-+		} else
-+			bfqq->requests_within_timer = 0;
-+		bfq_log_bfqq(bfqd, bfqq, "requests in time %d",
-+			     bfqq->requests_within_timer);
-+	}
-+
-+	if (bfqd->low_latency) {
-+		if (unlikely(time_is_after_jiffies(bfqq->split_time)))
-+			/* wraparound */
-+			bfqq->split_time =
-+				jiffies - bfqd->bfq_wr_min_idle_time - 1;
-+
-+		if (time_is_before_jiffies(bfqq->split_time +
-+					   bfqd->bfq_wr_min_idle_time)) {
-+			bfq_update_bfqq_wr_on_rq_arrival(bfqd, bfqq,
-+							 old_wr_coeff,
-+							 wr_or_deserves_wr,
-+							 *interactive,
-+							 in_burst,
-+							 soft_rt);
-+
-+			if (old_wr_coeff != bfqq->wr_coeff)
-+				bfqq->entity.prio_changed = 1;
-+		}
-+	}
-+
-+	bfqq->last_idle_bklogged = jiffies;
-+	bfqq->service_from_backlogged = 0;
-+	bfq_clear_bfqq_softrt_update(bfqq);
-+
-+	bfq_add_bfqq_busy(bfqd, bfqq);
-+
-+	/*
-+	 * Expire in-service queue only if preemption may be needed
-+	 * for guarantees. In this respect, the function
-+	 * next_queue_may_preempt just checks a simple, necessary
-+	 * condition, and not a sufficient condition based on
-+	 * timestamps. In fact, for the latter condition to be
-+	 * evaluated, timestamps would need first to be updated, and
-+	 * this operation is quite costly (see the comments on the
-+	 * function bfq_bfqq_update_budg_for_activation).
-+	 */
-+	if (bfqd->in_service_queue && bfqq_wants_to_preempt &&
-+	    bfqd->in_service_queue->wr_coeff < bfqq->wr_coeff &&
-+	    next_queue_may_preempt(bfqd)) {
-+		struct bfq_queue *in_serv =
-+			bfqd->in_service_queue;
-+		BUG_ON(in_serv == bfqq);
-+
-+		bfq_bfqq_expire(bfqd, bfqd->in_service_queue,
-+				false, BFQ_BFQQ_PREEMPTED);
-+	}
-+}
-+
-+static void bfq_add_request(struct request *rq)
-+{
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq);
-+	struct bfq_data *bfqd = bfqq->bfqd;
-+	struct request *next_rq, *prev;
-+	unsigned int old_wr_coeff = bfqq->wr_coeff;
-+	bool interactive = false;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "add_request: size %u %s",
-+		     blk_rq_sectors(rq), rq_is_sync(rq) ? "S" : "A");
-+
-+	if (bfqq->wr_coeff > 1) /* queue is being weight-raised */
-+		bfq_log_bfqq(bfqd, bfqq,
-+			"raising period dur %u/%u msec, old coeff %u, w %d(%d)",
-+			jiffies_to_msecs(jiffies - bfqq->last_wr_start_finish),
-+			jiffies_to_msecs(bfqq->wr_cur_max_time),
-+			bfqq->wr_coeff,
-+			bfqq->entity.weight, bfqq->entity.orig_weight);
-+
-+	bfqq->queued[rq_is_sync(rq)]++;
-+	bfqd->queued++;
-+
-+	elv_rb_add(&bfqq->sort_list, rq);
-+
-+	/*
-+	 * Check if this request is a better next-to-serve candidate.
-+	 */
-+	prev = bfqq->next_rq;
-+	next_rq = bfq_choose_req(bfqd, bfqq->next_rq, rq, bfqd->last_position);
-+	BUG_ON(!next_rq);
-+	bfqq->next_rq = next_rq;
-+
-+	/*
-+	 * Adjust priority tree position, if next_rq changes.
-+	 */
-+	if (prev != bfqq->next_rq)
-+		bfq_pos_tree_add_move(bfqd, bfqq);
-+
-+	if (!bfq_bfqq_busy(bfqq)) /* switching to busy ... */
-+		bfq_bfqq_handle_idle_busy_switch(bfqd, bfqq, old_wr_coeff,
-+						 rq, &interactive);
-+	else {
-+		if (bfqd->low_latency && old_wr_coeff == 1 && !rq_is_sync(rq) &&
-+		    time_is_before_jiffies(
-+				bfqq->last_wr_start_finish +
-+				bfqd->bfq_wr_min_inter_arr_async)) {
-+			bfqq->wr_coeff = bfqd->bfq_wr_coeff;
-+			bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
-+
-+			bfqd->wr_busy_queues++;
-+			BUG_ON(bfqd->wr_busy_queues > bfqd->busy_queues);
-+			bfqq->entity.prio_changed = 1;
-+			bfq_log_bfqq(bfqd, bfqq,
-+				     "non-idle wrais starting, "
-+				     "wr_max_time %u wr_busy %d",
-+				     jiffies_to_msecs(bfqq->wr_cur_max_time),
-+				     bfqd->wr_busy_queues);
-+		}
-+		if (prev != bfqq->next_rq)
-+			bfq_updated_next_req(bfqd, bfqq);
-+	}
-+
-+	/*
-+	 * Assign jiffies to last_wr_start_finish in the following
-+	 * cases:
-+	 *
-+	 * . if bfqq is not going to be weight-raised, because, for
-+	 *   non weight-raised queues, last_wr_start_finish stores the
-+	 *   arrival time of the last request; as of now, this piece
-+	 *   of information is used only for deciding whether to
-+	 *   weight-raise async queues
-+	 *
-+	 * . if bfqq is not weight-raised, because, if bfqq is now
-+	 *   switching to weight-raised, then last_wr_start_finish
-+	 *   stores the time when weight-raising starts
-+	 *
-+	 * . if bfqq is interactive, because, regardless of whether
-+	 *   bfqq is currently weight-raised, the weight-raising
-+	 *   period must start or restart (this case is considered
-+	 *   separately because it is not detected by the above
-+	 *   conditions, if bfqq is already weight-raised)
-+	 *
-+	 * last_wr_start_finish has to be updated also if bfqq is soft
-+	 * real-time, because the weight-raising period is constantly
-+	 * restarted on idle-to-busy transitions for these queues, but
-+	 * this is already done in bfq_bfqq_handle_idle_busy_switch if
-+	 * needed.
-+	 */
-+	if (bfqd->low_latency &&
-+		(old_wr_coeff == 1 || bfqq->wr_coeff == 1 || interactive))
-+		bfqq->last_wr_start_finish = jiffies;
-+}
-+
-+static struct request *bfq_find_rq_fmerge(struct bfq_data *bfqd,
-+					  struct bio *bio)
-+{
-+	struct task_struct *tsk = current;
-+	struct bfq_io_cq *bic;
-+	struct bfq_queue *bfqq;
-+
-+	bic = bfq_bic_lookup(bfqd, tsk->io_context);
-+	if (!bic)
-+		return NULL;
-+
-+	bfqq = bic_to_bfqq(bic, op_is_sync(bio->bi_opf));
-+	if (bfqq)
-+		return elv_rb_find(&bfqq->sort_list, bio_end_sector(bio));
-+
-+	return NULL;
-+}
-+
-+static sector_t get_sdist(sector_t last_pos, struct request *rq)
-+{
-+	sector_t sdist = 0;
-+
-+	if (last_pos) {
-+		if (last_pos < blk_rq_pos(rq))
-+			sdist = blk_rq_pos(rq) - last_pos;
-+		else
-+			sdist = last_pos - blk_rq_pos(rq);
-+	}
-+
-+	return sdist;
-+}
-+
-+static void bfq_activate_request(struct request_queue *q, struct request *rq)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	bfqd->rq_in_driver++;
-+}
-+
-+static void bfq_deactivate_request(struct request_queue *q, struct request *rq)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+
-+	BUG_ON(bfqd->rq_in_driver == 0);
-+	bfqd->rq_in_driver--;
-+}
-+
-+static void bfq_remove_request(struct request *rq)
-+{
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq);
-+	struct bfq_data *bfqd = bfqq->bfqd;
-+	const int sync = rq_is_sync(rq);
-+
-+	BUG_ON(bfqq->entity.service > bfqq->entity.budget &&
-+	       bfqq == bfqd->in_service_queue);
-+
-+	if (bfqq->next_rq == rq) {
-+		bfqq->next_rq = bfq_find_next_rq(bfqd, bfqq, rq);
-+		bfq_updated_next_req(bfqd, bfqq);
-+	}
-+
-+	if (rq->queuelist.prev != &rq->queuelist)
-+		list_del_init(&rq->queuelist);
-+	BUG_ON(bfqq->queued[sync] == 0);
-+	bfqq->queued[sync]--;
-+	bfqd->queued--;
-+	elv_rb_del(&bfqq->sort_list, rq);
-+
-+	if (RB_EMPTY_ROOT(&bfqq->sort_list)) {
-+		bfqq->next_rq = NULL;
-+
-+		BUG_ON(bfqq->entity.budget < 0);
-+
-+		if (bfq_bfqq_busy(bfqq) && bfqq != bfqd->in_service_queue) {
-+			BUG_ON(bfqq->ref < 2); /* referred by rq and on tree */
-+			bfq_del_bfqq_busy(bfqd, bfqq, false);
-+			/*
-+			 * bfqq emptied. In normal operation, when
-+			 * bfqq is empty, bfqq->entity.service and
-+			 * bfqq->entity.budget must contain,
-+			 * respectively, the service received and the
-+			 * budget used last time bfqq emptied. These
-+			 * facts do not hold in this case, as at least
-+			 * this last removal occurred while bfqq is
-+			 * not in service. To avoid inconsistencies,
-+			 * reset both bfqq->entity.service and
-+			 * bfqq->entity.budget, if bfqq has still a
-+			 * process that may issue I/O requests to it.
-+			 */
-+			bfqq->entity.budget = bfqq->entity.service = 0;
-+		}
-+
-+		/*
-+		 * Remove queue from request-position tree as it is empty.
-+		 */
-+		if (bfqq->pos_root) {
-+			rb_erase(&bfqq->pos_node, bfqq->pos_root);
-+			bfqq->pos_root = NULL;
-+		}
-+	}
-+
-+	if (rq->cmd_flags & REQ_META) {
-+		BUG_ON(bfqq->meta_pending == 0);
-+		bfqq->meta_pending--;
-+	}
-+	bfqg_stats_update_io_remove(bfqq_group(bfqq), rq->cmd_flags);
-+}
-+
-+static enum elv_merge bfq_merge(struct request_queue *q, struct request **req,
-+				struct bio *bio)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	struct request *__rq;
-+
-+	__rq = bfq_find_rq_fmerge(bfqd, bio);
-+	if (__rq && elv_bio_merge_ok(__rq, bio)) {
-+		*req = __rq;
-+		return ELEVATOR_FRONT_MERGE;
-+	}
-+
-+	return ELEVATOR_NO_MERGE;
-+}
-+
-+static void bfq_merged_request(struct request_queue *q, struct request *req,
-+			       enum elv_merge type)
-+{
-+	if (type == ELEVATOR_FRONT_MERGE &&
-+	    rb_prev(&req->rb_node) &&
-+	    blk_rq_pos(req) <
-+	    blk_rq_pos(container_of(rb_prev(&req->rb_node),
-+				    struct request, rb_node))) {
-+		struct bfq_queue *bfqq = RQ_BFQQ(req);
-+		struct bfq_data *bfqd = bfqq->bfqd;
-+		struct request *prev, *next_rq;
-+
-+		/* Reposition request in its sort_list */
-+		elv_rb_del(&bfqq->sort_list, req);
-+		elv_rb_add(&bfqq->sort_list, req);
-+		/* Choose next request to be served for bfqq */
-+		prev = bfqq->next_rq;
-+		next_rq = bfq_choose_req(bfqd, bfqq->next_rq, req,
-+					 bfqd->last_position);
-+		BUG_ON(!next_rq);
-+		bfqq->next_rq = next_rq;
-+		/*
-+		 * If next_rq changes, update both the queue's budget to
-+		 * fit the new request and the queue's position in its
-+		 * rq_pos_tree.
-+		 */
-+		if (prev != bfqq->next_rq) {
-+			bfq_updated_next_req(bfqd, bfqq);
-+			bfq_pos_tree_add_move(bfqd, bfqq);
-+		}
-+	}
-+}
-+
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+static void bfq_bio_merged(struct request_queue *q, struct request *req,
-+			   struct bio *bio)
-+{
-+	bfqg_stats_update_io_merged(bfqq_group(RQ_BFQQ(req)), bio->bi_opf);
-+}
-+#endif
-+
-+static void bfq_merged_requests(struct request_queue *q, struct request *rq,
-+				struct request *next)
-+{
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq), *next_bfqq = RQ_BFQQ(next);
-+
-+	/*
-+	 * If next and rq belong to the same bfq_queue and next is older
-+	 * than rq, then reposition rq in the fifo (by substituting next
-+	 * with rq). Otherwise, if next and rq belong to different
-+	 * bfq_queues, never reposition rq: in fact, we would have to
-+	 * reposition it with respect to next's position in its own fifo,
-+	 * which would most certainly be too expensive with respect to
-+	 * the benefits.
-+	 */
-+	if (bfqq == next_bfqq &&
-+	    !list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
-+	    next->fifo_time < rq->fifo_time) {
-+		list_del_init(&rq->queuelist);
-+		list_replace_init(&next->queuelist, &rq->queuelist);
-+		rq->fifo_time = next->fifo_time;
-+	}
-+
-+	if (bfqq->next_rq == next)
-+		bfqq->next_rq = rq;
-+
-+	bfq_remove_request(next);
-+	bfqg_stats_update_io_merged(bfqq_group(bfqq), next->cmd_flags);
-+}
-+
-+/* Must be called with bfqq != NULL */
-+static void bfq_bfqq_end_wr(struct bfq_queue *bfqq)
-+{
-+	BUG_ON(!bfqq);
-+
-+	if (bfq_bfqq_busy(bfqq)) {
-+		bfqq->bfqd->wr_busy_queues--;
-+		BUG_ON(bfqq->bfqd->wr_busy_queues < 0);
-+	}
-+	bfqq->wr_coeff = 1;
-+	bfqq->wr_cur_max_time = 0;
-+	bfqq->last_wr_start_finish = jiffies;
-+	/*
-+	 * Trigger a weight change on the next invocation of
-+	 * __bfq_entity_update_weight_prio.
-+	 */
-+	bfqq->entity.prio_changed = 1;
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		     "end_wr: wrais ending at %lu, rais_max_time %u",
-+		     bfqq->last_wr_start_finish,
-+		     jiffies_to_msecs(bfqq->wr_cur_max_time));
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "end_wr: wr_busy %d",
-+		     bfqq->bfqd->wr_busy_queues);
-+}
-+
-+static void bfq_end_wr_async_queues(struct bfq_data *bfqd,
-+				    struct bfq_group *bfqg)
-+{
-+	int i, j;
-+
-+	for (i = 0; i < 2; i++)
-+		for (j = 0; j < IOPRIO_BE_NR; j++)
-+			if (bfqg->async_bfqq[i][j])
-+				bfq_bfqq_end_wr(bfqg->async_bfqq[i][j]);
-+	if (bfqg->async_idle_bfqq)
-+		bfq_bfqq_end_wr(bfqg->async_idle_bfqq);
-+}
-+
-+static void bfq_end_wr(struct bfq_data *bfqd)
-+{
-+	struct bfq_queue *bfqq;
-+
-+	spin_lock_irq(bfqd->queue->queue_lock);
-+
-+	list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list)
-+		bfq_bfqq_end_wr(bfqq);
-+	list_for_each_entry(bfqq, &bfqd->idle_list, bfqq_list)
-+		bfq_bfqq_end_wr(bfqq);
-+	bfq_end_wr_async(bfqd);
-+
-+	spin_unlock_irq(bfqd->queue->queue_lock);
-+}
-+
-+static sector_t bfq_io_struct_pos(void *io_struct, bool request)
-+{
-+	if (request)
-+		return blk_rq_pos(io_struct);
-+	else
-+		return ((struct bio *)io_struct)->bi_iter.bi_sector;
-+}
-+
-+static int bfq_rq_close_to_sector(void *io_struct, bool request,
-+				  sector_t sector)
-+{
-+	return abs(bfq_io_struct_pos(io_struct, request) - sector) <=
-+	       BFQQ_CLOSE_THR;
-+}
-+
-+static struct bfq_queue *bfqq_find_close(struct bfq_data *bfqd,
-+					 struct bfq_queue *bfqq,
-+					 sector_t sector)
-+{
-+	struct rb_root *root = &bfq_bfqq_to_bfqg(bfqq)->rq_pos_tree;
-+	struct rb_node *parent, *node;
-+	struct bfq_queue *__bfqq;
-+
-+	if (RB_EMPTY_ROOT(root))
-+		return NULL;
-+
-+	/*
-+	 * First, if we find a request starting at the end of the last
-+	 * request, choose it.
-+	 */
-+	__bfqq = bfq_rq_pos_tree_lookup(bfqd, root, sector, &parent, NULL);
-+	if (__bfqq)
-+		return __bfqq;
-+
-+	/*
-+	 * If the exact sector wasn't found, the parent of the NULL leaf
-+	 * will contain the closest sector (rq_pos_tree sorted by
-+	 * next_request position).
-+	 */
-+	__bfqq = rb_entry(parent, struct bfq_queue, pos_node);
-+	if (bfq_rq_close_to_sector(__bfqq->next_rq, true, sector))
-+		return __bfqq;
-+
-+	if (blk_rq_pos(__bfqq->next_rq) < sector)
-+		node = rb_next(&__bfqq->pos_node);
-+	else
-+		node = rb_prev(&__bfqq->pos_node);
-+	if (!node)
-+		return NULL;
-+
-+	__bfqq = rb_entry(node, struct bfq_queue, pos_node);
-+	if (bfq_rq_close_to_sector(__bfqq->next_rq, true, sector))
-+		return __bfqq;
-+
-+	return NULL;
-+}
-+
-+static struct bfq_queue *bfq_find_close_cooperator(struct bfq_data *bfqd,
-+						   struct bfq_queue *cur_bfqq,
-+						   sector_t sector)
-+{
-+	struct bfq_queue *bfqq;
-+
-+	/*
-+	 * We shall notice if some of the queues are cooperating,
-+	 * e.g., working closely on the same area of the device. In
-+	 * that case, we can group them together and: 1) don't waste
-+	 * time idling, and 2) serve the union of their requests in
-+	 * the best possible order for throughput.
-+	 */
-+	bfqq = bfqq_find_close(bfqd, cur_bfqq, sector);
-+	if (!bfqq || bfqq == cur_bfqq)
-+		return NULL;
-+
-+	return bfqq;
-+}
-+
-+static struct bfq_queue *
-+bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq)
-+{
-+	int process_refs, new_process_refs;
-+	struct bfq_queue *__bfqq;
-+
-+	/*
-+	 * If there are no process references on the new_bfqq, then it is
-+	 * unsafe to follow the ->new_bfqq chain as other bfqq's in the chain
-+	 * may have dropped their last reference (not just their last process
-+	 * reference).
-+	 */
-+	if (!bfqq_process_refs(new_bfqq))
-+		return NULL;
-+
-+	/* Avoid a circular list and skip interim queue merges. */
-+	while ((__bfqq = new_bfqq->new_bfqq)) {
-+		if (__bfqq == bfqq)
-+			return NULL;
-+		new_bfqq = __bfqq;
-+	}
-+
-+	process_refs = bfqq_process_refs(bfqq);
-+	new_process_refs = bfqq_process_refs(new_bfqq);
-+	/*
-+	 * If the process for the bfqq has gone away, there is no
-+	 * sense in merging the queues.
-+	 */
-+	if (process_refs == 0 || new_process_refs == 0)
-+		return NULL;
-+
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "scheduling merge with queue %d",
-+		new_bfqq->pid);
-+
-+	/*
-+	 * Merging is just a redirection: the requests of the process
-+	 * owning one of the two queues are redirected to the other queue.
-+	 * The latter queue, in its turn, is set as shared if this is the
-+	 * first time that the requests of some process are redirected to
-+	 * it.
-+	 *
-+	 * We redirect bfqq to new_bfqq and not the opposite, because we
-+	 * are in the context of the process owning bfqq, hence we have
-+	 * the io_cq of this process. So we can immediately configure this
-+	 * io_cq to redirect the requests of the process to new_bfqq.
-+	 *
-+	 * NOTE, even if new_bfqq coincides with the in-service queue, the
-+	 * io_cq of new_bfqq is not available, because, if the in-service
-+	 * queue is shared, bfqd->in_service_bic may not point to the
-+	 * io_cq of the in-service queue.
-+	 * Redirecting the requests of the process owning bfqq to the
-+	 * currently in-service queue is in any case the best option, as
-+	 * we feed the in-service queue with new requests close to the
-+	 * last request served and, by doing so, hopefully increase the
-+	 * throughput.
-+	 */
-+	bfqq->new_bfqq = new_bfqq;
-+	new_bfqq->ref += process_refs;
-+	return new_bfqq;
-+}
-+
-+static bool bfq_may_be_close_cooperator(struct bfq_queue *bfqq,
-+					struct bfq_queue *new_bfqq)
-+{
-+	if (bfq_class_idle(bfqq) || bfq_class_idle(new_bfqq) ||
-+	    (bfqq->ioprio_class != new_bfqq->ioprio_class))
-+		return false;
-+
-+	/*
-+	 * If either of the queues has already been detected as seeky,
-+	 * then merging it with the other queue is unlikely to lead to
-+	 * sequential I/O.
-+	 */
-+	if (BFQQ_SEEKY(bfqq) || BFQQ_SEEKY(new_bfqq))
-+		return false;
-+
-+	/*
-+	 * Interleaved I/O is known to be done by (some) applications
-+	 * only for reads, so it does not make sense to merge async
-+	 * queues.
-+	 */
-+	if (!bfq_bfqq_sync(bfqq) || !bfq_bfqq_sync(new_bfqq))
-+		return false;
-+
-+	return true;
-+}
-+
-+/*
-+ * If this function returns true, then bfqq cannot be merged. The idea
-+ * is that true cooperation happens very early after processes start
-+ * to do I/O. Usually, late cooperations are just accidental false
-+ * positives. In case bfqq is weight-raised, such false positives
-+ * would evidently degrade latency guarantees for bfqq.
-+ */
-+static bool wr_from_too_long(struct bfq_queue *bfqq)
-+{
-+	return bfqq->wr_coeff > 1 &&
-+		time_is_before_jiffies(bfqq->last_wr_start_finish +
-+				       msecs_to_jiffies(100));
-+}
-+
-+/*
-+ * Attempt to schedule a merge of bfqq with the currently in-service
-+ * queue or with a close queue among the scheduled queues.  Return
-+ * NULL if no merge was scheduled, a pointer to the shared bfq_queue
-+ * structure otherwise.
-+ *
-+ * The OOM queue is not allowed to participate to cooperation: in fact, since
-+ * the requests temporarily redirected to the OOM queue could be redirected
-+ * again to dedicated queues at any time, the state needed to correctly
-+ * handle merging with the OOM queue would be quite complex and expensive
-+ * to maintain. Besides, in such a critical condition as an out of memory,
-+ * the benefits of queue merging may be little relevant, or even negligible.
-+ *
-+ * Weight-raised queues can be merged only if their weight-raising
-+ * period has just started. In fact cooperating processes are usually
-+ * started together. Thus, with this filter we avoid false positives
-+ * that would jeopardize low-latency guarantees.
-+ *
-+ * WARNING: queue merging may impair fairness among non-weight raised
-+ * queues, for at least two reasons: 1) the original weight of a
-+ * merged queue may change during the merged state, 2) even being the
-+ * weight the same, a merged queue may be bloated with many more
-+ * requests than the ones produced by its originally-associated
-+ * process.
-+ */
-+static struct bfq_queue *
-+bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+		     void *io_struct, bool request)
-+{
-+	struct bfq_queue *in_service_bfqq, *new_bfqq;
-+
-+	if (bfqq->new_bfqq)
-+		return bfqq->new_bfqq;
-+
-+	if (io_struct && wr_from_too_long(bfqq) &&
-+	    likely(bfqq != &bfqd->oom_bfqq))
-+		bfq_log_bfqq(bfqd, bfqq,
-+			     "would have looked for coop, but bfq%d wr",
-+			bfqq->pid);
-+
-+	if (!io_struct ||
-+	    wr_from_too_long(bfqq) ||
-+	    unlikely(bfqq == &bfqd->oom_bfqq))
-+		return NULL;
-+
-+	/* If there is only one backlogged queue, don't search. */
-+	if (bfqd->busy_queues == 1)
-+		return NULL;
-+
-+	in_service_bfqq = bfqd->in_service_queue;
-+
-+	if (in_service_bfqq && in_service_bfqq != bfqq &&
-+	    bfqd->in_service_bic && wr_from_too_long(in_service_bfqq)
-+	    && likely(in_service_bfqq == &bfqd->oom_bfqq))
-+		bfq_log_bfqq(bfqd, bfqq,
-+		"would have tried merge with in-service-queue, but wr");
-+
-+	if (!in_service_bfqq || in_service_bfqq == bfqq ||
-+	    !bfqd->in_service_bic || wr_from_too_long(in_service_bfqq) ||
-+	    unlikely(in_service_bfqq == &bfqd->oom_bfqq))
-+		goto check_scheduled;
-+
-+	if (bfq_rq_close_to_sector(io_struct, request, bfqd->last_position) &&
-+	    bfqq->entity.parent == in_service_bfqq->entity.parent &&
-+	    bfq_may_be_close_cooperator(bfqq, in_service_bfqq)) {
-+		new_bfqq = bfq_setup_merge(bfqq, in_service_bfqq);
-+		if (new_bfqq)
-+			return new_bfqq;
-+	}
-+	/*
-+	 * Check whether there is a cooperator among currently scheduled
-+	 * queues. The only thing we need is that the bio/request is not
-+	 * NULL, as we need it to establish whether a cooperator exists.
-+	 */
-+check_scheduled:
-+	new_bfqq = bfq_find_close_cooperator(bfqd, bfqq,
-+			bfq_io_struct_pos(io_struct, request));
-+
-+	BUG_ON(new_bfqq && bfqq->entity.parent != new_bfqq->entity.parent);
-+
-+	if (new_bfqq && wr_from_too_long(new_bfqq) &&
-+	    likely(new_bfqq != &bfqd->oom_bfqq) &&
-+	    bfq_may_be_close_cooperator(bfqq, new_bfqq))
-+		bfq_log_bfqq(bfqd, bfqq,
-+			     "would have merged with bfq%d, but wr",
-+			     new_bfqq->pid);
-+
-+	if (new_bfqq && !wr_from_too_long(new_bfqq) &&
-+	    likely(new_bfqq != &bfqd->oom_bfqq) &&
-+	    bfq_may_be_close_cooperator(bfqq, new_bfqq))
-+		return bfq_setup_merge(bfqq, new_bfqq);
-+
-+	return NULL;
-+}
-+
-+static void bfq_bfqq_save_state(struct bfq_queue *bfqq)
-+{
-+	struct bfq_io_cq *bic = bfqq->bic;
-+
-+	/*
-+	 * If !bfqq->bic, the queue is already shared or its requests
-+	 * have already been redirected to a shared queue; both idle window
-+	 * and weight raising state have already been saved. Do nothing.
-+	 */
-+	if (!bic)
-+		return;
-+
-+	bic->saved_has_short_ttime = bfq_bfqq_has_short_ttime(bfqq);
-+	bic->saved_IO_bound = bfq_bfqq_IO_bound(bfqq);
-+	bic->saved_in_large_burst = bfq_bfqq_in_large_burst(bfqq);
-+	bic->was_in_burst_list = !hlist_unhashed(&bfqq->burst_list_node);
-+	bic->saved_wr_coeff = bfqq->wr_coeff;
-+	bic->saved_wr_start_at_switch_to_srt = bfqq->wr_start_at_switch_to_srt;
-+	bic->saved_last_wr_start_finish = bfqq->last_wr_start_finish;
-+	bic->saved_wr_cur_max_time = bfqq->wr_cur_max_time;
-+	BUG_ON(time_is_after_jiffies(bfqq->last_wr_start_finish));
-+}
-+
-+static void bfq_get_bic_reference(struct bfq_queue *bfqq)
-+{
-+	/*
-+	 * If bfqq->bic has a non-NULL value, the bic to which it belongs
-+	 * is about to begin using a shared bfq_queue.
-+	 */
-+	if (bfqq->bic)
-+		atomic_long_inc(&bfqq->bic->icq.ioc->refcount);
-+}
-+
-+static void
-+bfq_merge_bfqqs(struct bfq_data *bfqd, struct bfq_io_cq *bic,
-+		struct bfq_queue *bfqq, struct bfq_queue *new_bfqq)
-+{
-+	bfq_log_bfqq(bfqd, bfqq, "merging with queue %lu",
-+		     (unsigned long) new_bfqq->pid);
-+	/* Save weight raising and idle window of the merged queues */
-+	bfq_bfqq_save_state(bfqq);
-+	bfq_bfqq_save_state(new_bfqq);
-+	if (bfq_bfqq_IO_bound(bfqq))
-+		bfq_mark_bfqq_IO_bound(new_bfqq);
-+	bfq_clear_bfqq_IO_bound(bfqq);
-+
-+	/*
-+	 * If bfqq is weight-raised, then let new_bfqq inherit
-+	 * weight-raising. To reduce false positives, neglect the case
-+	 * where bfqq has just been created, but has not yet made it
-+	 * to be weight-raised (which may happen because EQM may merge
-+	 * bfqq even before bfq_add_request is executed for the first
-+	 * time for bfqq). Handling this case would however be very
-+	 * easy, thanks to the flag just_created.
-+	 */
-+	if (new_bfqq->wr_coeff == 1 && bfqq->wr_coeff > 1) {
-+		new_bfqq->wr_coeff = bfqq->wr_coeff;
-+		new_bfqq->wr_cur_max_time = bfqq->wr_cur_max_time;
-+		new_bfqq->last_wr_start_finish = bfqq->last_wr_start_finish;
-+		new_bfqq->wr_start_at_switch_to_srt =
-+			bfqq->wr_start_at_switch_to_srt;
-+		if (bfq_bfqq_busy(new_bfqq)) {
-+			bfqd->wr_busy_queues++;
-+			BUG_ON(bfqd->wr_busy_queues > bfqd->busy_queues);
-+		}
-+
-+		new_bfqq->entity.prio_changed = 1;
-+		bfq_log_bfqq(bfqd, new_bfqq,
-+			     "wr start after merge with %d, rais_max_time %u",
-+			     bfqq->pid,
-+			     jiffies_to_msecs(bfqq->wr_cur_max_time));
-+	}
-+
-+	if (bfqq->wr_coeff > 1) { /* bfqq has given its wr to new_bfqq */
-+		bfqq->wr_coeff = 1;
-+		bfqq->entity.prio_changed = 1;
-+		if (bfq_bfqq_busy(bfqq)) {
-+			bfqd->wr_busy_queues--;
-+			BUG_ON(bfqd->wr_busy_queues < 0);
-+		}
-+
-+	}
-+
-+	bfq_log_bfqq(bfqd, new_bfqq, "merge_bfqqs: wr_busy %d",
-+		     bfqd->wr_busy_queues);
-+
-+	/*
-+	 * Grab a reference to the bic, to prevent it from being destroyed
-+	 * before being possibly touched by a bfq_split_bfqq().
-+	 */
-+	bfq_get_bic_reference(bfqq);
-+	bfq_get_bic_reference(new_bfqq);
-+	/*
-+	 * Merge queues (that is, let bic redirect its requests to new_bfqq)
-+	 */
-+	bic_set_bfqq(bic, new_bfqq, 1);
-+	bfq_mark_bfqq_coop(new_bfqq);
-+	/*
-+	 * new_bfqq now belongs to at least two bics (it is a shared queue):
-+	 * set new_bfqq->bic to NULL. bfqq either:
-+	 * - does not belong to any bic any more, and hence bfqq->bic must
-+	 *   be set to NULL, or
-+	 * - is a queue whose owning bics have already been redirected to a
-+	 *   different queue, hence the queue is destined to not belong to
-+	 *   any bic soon and bfqq->bic is already NULL (therefore the next
-+	 *   assignment causes no harm).
-+	 */
-+	new_bfqq->bic = NULL;
-+	bfqq->bic = NULL;
-+	/* release process reference to bfqq */
-+	bfq_put_queue(bfqq);
-+}
-+
-+static int bfq_allow_bio_merge(struct request_queue *q, struct request *rq,
-+			       struct bio *bio)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	bool is_sync = op_is_sync(bio->bi_opf);
-+	struct bfq_io_cq *bic;
-+	struct bfq_queue *bfqq, *new_bfqq;
-+
-+	/*
-+	 * Disallow merge of a sync bio into an async request.
-+	 */
-+	if (is_sync && !rq_is_sync(rq))
-+		return false;
-+
-+	/*
-+	 * Lookup the bfqq that this bio will be queued with. Allow
-+	 * merge only if rq is queued there.
-+	 * Queue lock is held here.
-+	 */
-+	bic = bfq_bic_lookup(bfqd, current->io_context);
-+	if (!bic)
-+		return false;
-+
-+	bfqq = bic_to_bfqq(bic, is_sync);
-+	/*
-+	 * We take advantage of this function to perform an early merge
-+	 * of the queues of possible cooperating processes.
-+	 */
-+	if (bfqq) {
-+		new_bfqq = bfq_setup_cooperator(bfqd, bfqq, bio, false);
-+		if (new_bfqq) {
-+			bfq_merge_bfqqs(bfqd, bic, bfqq, new_bfqq);
-+			/*
-+			 * If we get here, the bio will be queued in the
-+			 * shared queue, i.e., new_bfqq, so use new_bfqq
-+			 * to decide whether bio and rq can be merged.
-+			 */
-+			bfqq = new_bfqq;
-+		}
-+	}
-+
-+	return bfqq == RQ_BFQQ(rq);
-+}
-+
-+static int bfq_allow_rq_merge(struct request_queue *q, struct request *rq,
-+			      struct request *next)
-+{
-+	return RQ_BFQQ(rq) == RQ_BFQQ(next);
-+}
-+
-+/*
-+ * Set the maximum time for the in-service queue to consume its
-+ * budget. This prevents seeky processes from lowering the throughput.
-+ * In practice, a time-slice service scheme is used with seeky
-+ * processes.
-+ */
-+static void bfq_set_budget_timeout(struct bfq_data *bfqd,
-+				   struct bfq_queue *bfqq)
-+{
-+	unsigned int timeout_coeff;
-+
-+	if (bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time)
-+		timeout_coeff = 1;
-+	else
-+		timeout_coeff = bfqq->entity.weight / bfqq->entity.orig_weight;
-+
-+	bfqd->last_budget_start = ktime_get();
-+
-+	bfqq->budget_timeout = jiffies +
-+		bfqd->bfq_timeout * timeout_coeff;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "set budget_timeout %u",
-+		jiffies_to_msecs(bfqd->bfq_timeout * timeout_coeff));
-+}
-+
-+static void __bfq_set_in_service_queue(struct bfq_data *bfqd,
-+				       struct bfq_queue *bfqq)
-+{
-+	if (bfqq) {
-+		bfqg_stats_update_avg_queue_size(bfqq_group(bfqq));
-+		bfq_mark_bfqq_must_alloc(bfqq);
-+		bfq_clear_bfqq_fifo_expire(bfqq);
-+
-+		bfqd->budgets_assigned = (bfqd->budgets_assigned*7 + 256) / 8;
-+
-+		BUG_ON(bfqq == bfqd->in_service_queue);
-+		BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list));
-+
-+		if (time_is_before_jiffies(bfqq->last_wr_start_finish) &&
-+		    bfqq->wr_coeff > 1 &&
-+		    bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time &&
-+		    time_is_before_jiffies(bfqq->budget_timeout)) {
-+			/*
-+			 * For soft real-time queues, move the start
-+			 * of the weight-raising period forward by the
-+			 * time the queue has not received any
-+			 * service. Otherwise, a relatively long
-+			 * service delay is likely to cause the
-+			 * weight-raising period of the queue to end,
-+			 * because of the short duration of the
-+			 * weight-raising period of a soft real-time
-+			 * queue.  It is worth noting that this move
-+			 * is not so dangerous for the other queues,
-+			 * because soft real-time queues are not
-+			 * greedy.
-+			 *
-+			 * To not add a further variable, we use the
-+			 * overloaded field budget_timeout to
-+			 * determine for how long the queue has not
-+			 * received service, i.e., how much time has
-+			 * elapsed since the queue expired. However,
-+			 * this is a little imprecise, because
-+			 * budget_timeout is set to jiffies if bfqq
-+			 * not only expires, but also remains with no
-+			 * request.
-+			 */
-+			if (time_after(bfqq->budget_timeout,
-+				       bfqq->last_wr_start_finish))
-+				bfqq->last_wr_start_finish +=
-+					jiffies - bfqq->budget_timeout;
-+			else
-+				bfqq->last_wr_start_finish = jiffies;
-+
-+			if (time_is_after_jiffies(bfqq->last_wr_start_finish)) {
-+			       pr_crit(
-+			       "BFQ WARNING:last %lu budget %lu jiffies %lu",
-+			       bfqq->last_wr_start_finish,
-+			       bfqq->budget_timeout,
-+			       jiffies);
-+			       pr_crit("diff %lu", jiffies -
-+				       max_t(unsigned long,
-+					     bfqq->last_wr_start_finish,
-+					     bfqq->budget_timeout));
-+			       bfqq->last_wr_start_finish = jiffies;
-+			}
-+		}
-+
-+		bfq_set_budget_timeout(bfqd, bfqq);
-+		bfq_log_bfqq(bfqd, bfqq,
-+			     "set_in_service_queue, cur-budget = %d",
-+			     bfqq->entity.budget);
-+	} else
-+		bfq_log(bfqd, "set_in_service_queue: NULL");
-+
-+	bfqd->in_service_queue = bfqq;
-+}
-+
-+/*
-+ * Get and set a new queue for service.
-+ */
-+static struct bfq_queue *bfq_set_in_service_queue(struct bfq_data *bfqd)
-+{
-+	struct bfq_queue *bfqq = bfq_get_next_queue(bfqd);
-+
-+	__bfq_set_in_service_queue(bfqd, bfqq);
-+	return bfqq;
-+}
-+
-+static void bfq_arm_slice_timer(struct bfq_data *bfqd)
-+{
-+	struct bfq_queue *bfqq = bfqd->in_service_queue;
-+	struct bfq_io_cq *bic;
-+	u32 sl;
-+
-+	BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list));
-+
-+	/* Processes have exited, don't wait. */
-+	bic = bfqd->in_service_bic;
-+	if (!bic || atomic_read(&bic->icq.ioc->active_ref) == 0)
-+		return;
-+
-+	bfq_mark_bfqq_wait_request(bfqq);
-+
-+	/*
-+	 * We don't want to idle for seeks, but we do want to allow
-+	 * fair distribution of slice time for a process doing back-to-back
-+	 * seeks. So allow a little bit of time for him to submit a new rq.
-+	 *
-+	 * To prevent processes with (partly) seeky workloads from
-+	 * being too ill-treated, grant them a small fraction of the
-+	 * assigned budget before reducing the waiting time to
-+	 * BFQ_MIN_TT. This happened to help reduce latency.
-+	 */
-+	sl = bfqd->bfq_slice_idle;
-+	/*
-+	 * Unless the queue is being weight-raised or the scenario is
-+	 * asymmetric, grant only minimum idle time if the queue
-+	 * is seeky. A long idling is preserved for a weight-raised
-+	 * queue, or, more in general, in an asymemtric scenario,
-+	 * because a long idling is needed for guaranteeing to a queue
-+	 * its reserved share of the throughput (in particular, it is
-+	 * needed if the queue has a higher weight than some other
-+	 * queue).
-+	 */
-+	if (BFQQ_SEEKY(bfqq) && bfqq->wr_coeff == 1 &&
-+	    bfq_symmetric_scenario(bfqd))
-+		sl = min_t(u32, sl, BFQ_MIN_TT);
-+
-+	bfqd->last_idling_start = ktime_get();
-+	hrtimer_start(&bfqd->idle_slice_timer, ns_to_ktime(sl),
-+		      HRTIMER_MODE_REL);
-+	bfqg_stats_set_start_idle_time(bfqq_group(bfqq));
-+	bfq_log(bfqd, "arm idle: %ld/%ld ms",
-+		sl / NSEC_PER_MSEC, bfqd->bfq_slice_idle / NSEC_PER_MSEC);
-+}
-+
-+/*
-+ * In autotuning mode, max_budget is dynamically recomputed as the
-+ * amount of sectors transferred in timeout at the estimated peak
-+ * rate. This enables BFQ to utilize a full timeslice with a full
-+ * budget, even if the in-service queue is served at peak rate. And
-+ * this maximises throughput with sequential workloads.
-+ */
-+static unsigned long bfq_calc_max_budget(struct bfq_data *bfqd)
-+{
-+	return (u64)bfqd->peak_rate * USEC_PER_MSEC *
-+		jiffies_to_msecs(bfqd->bfq_timeout)>>BFQ_RATE_SHIFT;
-+}
-+
-+/*
-+ * Update parameters related to throughput and responsiveness, as a
-+ * function of the estimated peak rate. See comments on
-+ * bfq_calc_max_budget(), and on T_slow and T_fast arrays.
-+ */
-+static void update_thr_responsiveness_params(struct bfq_data *bfqd)
-+{
-+	int dev_type = blk_queue_nonrot(bfqd->queue);
-+
-+	if (bfqd->bfq_user_max_budget == 0) {
-+		bfqd->bfq_max_budget =
-+			bfq_calc_max_budget(bfqd);
-+		BUG_ON(bfqd->bfq_max_budget < 0);
-+		bfq_log(bfqd, "new max_budget = %d",
-+			bfqd->bfq_max_budget);
-+	}
-+
-+	if (bfqd->device_speed == BFQ_BFQD_FAST &&
-+	    bfqd->peak_rate < device_speed_thresh[dev_type]) {
-+		bfqd->device_speed = BFQ_BFQD_SLOW;
-+		bfqd->RT_prod = R_slow[dev_type] *
-+			T_slow[dev_type];
-+	} else if (bfqd->device_speed == BFQ_BFQD_SLOW &&
-+		   bfqd->peak_rate > device_speed_thresh[dev_type]) {
-+		bfqd->device_speed = BFQ_BFQD_FAST;
-+		bfqd->RT_prod = R_fast[dev_type] *
-+			T_fast[dev_type];
-+	}
-+
-+	bfq_log(bfqd,
-+"dev_type %s dev_speed_class = %s (%llu sects/sec), thresh %llu setcs/sec",
-+		dev_type == 0 ? "ROT" : "NONROT",
-+		bfqd->device_speed == BFQ_BFQD_FAST ? "FAST" : "SLOW",
-+		bfqd->device_speed == BFQ_BFQD_FAST ?
-+		(USEC_PER_SEC*(u64)R_fast[dev_type])>>BFQ_RATE_SHIFT :
-+		(USEC_PER_SEC*(u64)R_slow[dev_type])>>BFQ_RATE_SHIFT,
-+		(USEC_PER_SEC*(u64)device_speed_thresh[dev_type])>>
-+		BFQ_RATE_SHIFT);
-+}
-+
-+static void bfq_reset_rate_computation(struct bfq_data *bfqd, struct request *rq)
-+{
-+	if (rq != NULL) { /* new rq dispatch now, reset accordingly */
-+		bfqd->last_dispatch = bfqd->first_dispatch = ktime_get_ns() ;
-+		bfqd->peak_rate_samples = 1;
-+		bfqd->sequential_samples = 0;
-+		bfqd->tot_sectors_dispatched = bfqd->last_rq_max_size =
-+			blk_rq_sectors(rq);
-+	} else /* no new rq dispatched, just reset the number of samples */
-+		bfqd->peak_rate_samples = 0; /* full re-init on next disp. */
-+
-+	bfq_log(bfqd,
-+		"reset_rate_computation at end, sample %u/%u tot_sects %llu",
-+		bfqd->peak_rate_samples, bfqd->sequential_samples,
-+		bfqd->tot_sectors_dispatched);
-+}
-+
-+static void bfq_update_rate_reset(struct bfq_data *bfqd, struct request *rq)
-+{
-+	u32 rate, weight, divisor;
-+
-+	/*
-+	 * For the convergence property to hold (see comments on
-+	 * bfq_update_peak_rate()) and for the assessment to be
-+	 * reliable, a minimum number of samples must be present, and
-+	 * a minimum amount of time must have elapsed. If not so, do
-+	 * not compute new rate. Just reset parameters, to get ready
-+	 * for a new evaluation attempt.
-+	 */
-+	if (bfqd->peak_rate_samples < BFQ_RATE_MIN_SAMPLES ||
-+	    bfqd->delta_from_first < BFQ_RATE_MIN_INTERVAL) {
-+		bfq_log(bfqd,
-+	"update_rate_reset: only resetting, delta_first %lluus samples %d",
-+			bfqd->delta_from_first>>10, bfqd->peak_rate_samples);
-+		goto reset_computation;
-+	}
-+
-+	/*
-+	 * If a new request completion has occurred after last
-+	 * dispatch, then, to approximate the rate at which requests
-+	 * have been served by the device, it is more precise to
-+	 * extend the observation interval to the last completion.
-+	 */
-+	bfqd->delta_from_first =
-+		max_t(u64, bfqd->delta_from_first,
-+		      bfqd->last_completion - bfqd->first_dispatch);
-+
-+	BUG_ON(bfqd->delta_from_first == 0);
-+	/*
-+	 * Rate computed in sects/usec, and not sects/nsec, for
-+	 * precision issues.
-+	 */
-+	rate = div64_ul(bfqd->tot_sectors_dispatched<<BFQ_RATE_SHIFT,
-+			div_u64(bfqd->delta_from_first, NSEC_PER_USEC));
-+
-+	bfq_log(bfqd,
-+"update_rate_reset: tot_sects %llu delta_first %lluus rate %llu sects/s (%d)",
-+		bfqd->tot_sectors_dispatched, bfqd->delta_from_first>>10,
-+		((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT),
-+		rate > 20<<BFQ_RATE_SHIFT);
-+
-+	/*
-+	 * Peak rate not updated if:
-+	 * - the percentage of sequential dispatches is below 3/4 of the
-+	 *   total, and rate is below the current estimated peak rate
-+	 * - rate is unreasonably high (> 20M sectors/sec)
-+	 */
-+	if ((bfqd->sequential_samples < (3 * bfqd->peak_rate_samples)>>2 &&
-+	     rate <= bfqd->peak_rate) ||
-+		rate > 20<<BFQ_RATE_SHIFT) {
-+		bfq_log(bfqd,
-+		"update_rate_reset: goto reset, samples %u/%u rate/peak %llu/%llu",
-+		bfqd->peak_rate_samples, bfqd->sequential_samples,
-+		((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT),
-+		((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT));
-+		goto reset_computation;
-+	} else {
-+		bfq_log(bfqd,
-+		"update_rate_reset: do update, samples %u/%u rate/peak %llu/%llu",
-+		bfqd->peak_rate_samples, bfqd->sequential_samples,
-+		((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT),
-+		((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT));
-+	}
-+
-+	/*
-+	 * We have to update the peak rate, at last! To this purpose,
-+	 * we use a low-pass filter. We compute the smoothing constant
-+	 * of the filter as a function of the 'weight' of the new
-+	 * measured rate.
-+	 *
-+	 * As can be seen in next formulas, we define this weight as a
-+	 * quantity proportional to how sequential the workload is,
-+	 * and to how long the observation time interval is.
-+	 *
-+	 * The weight runs from 0 to 8. The maximum value of the
-+	 * weight, 8, yields the minimum value for the smoothing
-+	 * constant. At this minimum value for the smoothing constant,
-+	 * the measured rate contributes for half of the next value of
-+	 * the estimated peak rate.
-+	 *
-+	 * So, the first step is to compute the weight as a function
-+	 * of how sequential the workload is. Note that the weight
-+	 * cannot reach 9, because bfqd->sequential_samples cannot
-+	 * become equal to bfqd->peak_rate_samples, which, in its
-+	 * turn, holds true because bfqd->sequential_samples is not
-+	 * incremented for the first sample.
-+	 */
-+	weight = (9 * bfqd->sequential_samples) / bfqd->peak_rate_samples;
-+
-+	/*
-+	 * Second step: further refine the weight as a function of the
-+	 * duration of the observation interval.
-+	 */
-+	weight = min_t(u32, 8,
-+		       div_u64(weight * bfqd->delta_from_first,
-+			       BFQ_RATE_REF_INTERVAL));
-+
-+	/*
-+	 * Divisor ranging from 10, for minimum weight, to 2, for
-+	 * maximum weight.
-+	 */
-+	divisor = 10 - weight;
-+	BUG_ON(divisor == 0);
-+
-+	/*
-+	 * Finally, update peak rate:
-+	 *
-+	 * peak_rate = peak_rate * (divisor-1) / divisor  +  rate / divisor
-+	 */
-+	bfqd->peak_rate *= divisor-1;
-+	bfqd->peak_rate /= divisor;
-+	rate /= divisor; /* smoothing constant alpha = 1/divisor */
-+
-+	bfq_log(bfqd,
-+		"update_rate_reset: divisor %d tmp_peak_rate %llu tmp_rate %u",
-+		divisor,
-+		((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT),
-+		(u32)((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT));
-+
-+	BUG_ON(bfqd->peak_rate == 0);
-+	BUG_ON(bfqd->peak_rate > 20<<BFQ_RATE_SHIFT);
-+
-+	bfqd->peak_rate += rate;
-+	update_thr_responsiveness_params(bfqd);
-+	BUG_ON(bfqd->peak_rate > 20<<BFQ_RATE_SHIFT);
-+
-+reset_computation:
-+	bfq_reset_rate_computation(bfqd, rq);
-+}
-+
-+/*
-+ * Update the read/write peak rate (the main quantity used for
-+ * auto-tuning, see update_thr_responsiveness_params()).
-+ *
-+ * It is not trivial to estimate the peak rate (correctly): because of
-+ * the presence of sw and hw queues between the scheduler and the
-+ * device components that finally serve I/O requests, it is hard to
-+ * say exactly when a given dispatched request is served inside the
-+ * device, and for how long. As a consequence, it is hard to know
-+ * precisely at what rate a given set of requests is actually served
-+ * by the device.
-+ *
-+ * On the opposite end, the dispatch time of any request is trivially
-+ * available, and, from this piece of information, the "dispatch rate"
-+ * of requests can be immediately computed. So, the idea in the next
-+ * function is to use what is known, namely request dispatch times
-+ * (plus, when useful, request completion times), to estimate what is
-+ * unknown, namely in-device request service rate.
-+ *
-+ * The main issue is that, because of the above facts, the rate at
-+ * which a certain set of requests is dispatched over a certain time
-+ * interval can vary greatly with respect to the rate at which the
-+ * same requests are then served. But, since the size of any
-+ * intermediate queue is limited, and the service scheme is lossless
-+ * (no request is silently dropped), the following obvious convergence
-+ * property holds: the number of requests dispatched MUST become
-+ * closer and closer to the number of requests completed as the
-+ * observation interval grows. This is the key property used in
-+ * the next function to estimate the peak service rate as a function
-+ * of the observed dispatch rate. The function assumes to be invoked
-+ * on every request dispatch.
-+ */
-+static void bfq_update_peak_rate(struct bfq_data *bfqd, struct request *rq)
-+{
-+	u64 now_ns = ktime_get_ns();
-+
-+	if (bfqd->peak_rate_samples == 0) { /* first dispatch */
-+		bfq_log(bfqd,
-+		"update_peak_rate: goto reset, samples %d",
-+				bfqd->peak_rate_samples) ;
-+		bfq_reset_rate_computation(bfqd, rq);
-+		goto update_last_values; /* will add one sample */
-+	}
-+
-+	/*
-+	 * Device idle for very long: the observation interval lasting
-+	 * up to this dispatch cannot be a valid observation interval
-+	 * for computing a new peak rate (similarly to the late-
-+	 * completion event in bfq_completed_request()). Go to
-+	 * update_rate_and_reset to have the following three steps
-+	 * taken:
-+	 * - close the observation interval at the last (previous)
-+	 *   request dispatch or completion
-+	 * - compute rate, if possible, for that observation interval
-+	 * - start a new observation interval with this dispatch
-+	 */
-+	if (now_ns - bfqd->last_dispatch > 100*NSEC_PER_MSEC &&
-+	    bfqd->rq_in_driver == 0) {
-+		bfq_log(bfqd,
-+"update_peak_rate: jumping to updating&resetting delta_last %lluus samples %d",
-+			(now_ns - bfqd->last_dispatch)>>10,
-+			bfqd->peak_rate_samples) ;
-+		goto update_rate_and_reset;
-+	}
-+
-+	/* Update sampling information */
-+	bfqd->peak_rate_samples++;
-+
-+	if ((bfqd->rq_in_driver > 0 ||
-+		now_ns - bfqd->last_completion < BFQ_MIN_TT)
-+	     && get_sdist(bfqd->last_position, rq) < BFQQ_SEEK_THR)
-+		bfqd->sequential_samples++;
-+
-+	bfqd->tot_sectors_dispatched += blk_rq_sectors(rq);
-+
-+	/* Reset max observed rq size every 32 dispatches */
-+	if (likely(bfqd->peak_rate_samples % 32))
-+		bfqd->last_rq_max_size =
-+			max_t(u32, blk_rq_sectors(rq), bfqd->last_rq_max_size);
-+	else
-+		bfqd->last_rq_max_size = blk_rq_sectors(rq);
-+
-+	bfqd->delta_from_first = now_ns - bfqd->first_dispatch;
-+
-+	bfq_log(bfqd,
-+	"update_peak_rate: added samples %u/%u tot_sects %llu delta_first %lluus",
-+		bfqd->peak_rate_samples, bfqd->sequential_samples,
-+		bfqd->tot_sectors_dispatched,
-+		bfqd->delta_from_first>>10);
-+
-+	/* Target observation interval not yet reached, go on sampling */
-+	if (bfqd->delta_from_first < BFQ_RATE_REF_INTERVAL)
-+		goto update_last_values;
-+
-+update_rate_and_reset:
-+	bfq_update_rate_reset(bfqd, rq);
-+update_last_values:
-+	bfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
-+	bfqd->last_dispatch = now_ns;
-+
-+	bfq_log(bfqd,
-+	"update_peak_rate: delta_first %lluus last_pos %llu peak_rate %llu",
-+		(now_ns - bfqd->first_dispatch)>>10,
-+		(unsigned long long) bfqd->last_position,
-+		((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT));
-+	bfq_log(bfqd,
-+	"update_peak_rate: samples at end %d", bfqd->peak_rate_samples);
-+}
-+
-+/*
-+ * Move request from internal lists to the dispatch list of the request queue
-+ */
-+static void bfq_dispatch_insert(struct request_queue *q, struct request *rq)
-+{
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq);
-+
-+	/*
-+	 * For consistency, the next instruction should have been executed
-+	 * after removing the request from the queue and dispatching it.
-+	 * We execute instead this instruction before bfq_remove_request()
-+	 * (and hence introduce a temporary inconsistency), for efficiency.
-+	 * In fact, in a forced_dispatch, this prevents two counters related
-+	 * to bfqq->dispatched to risk to be uselessly decremented if bfqq
-+	 * is not in service, and then to be incremented again after
-+	 * incrementing bfqq->dispatched.
-+	 */
-+	bfqq->dispatched++;
-+	bfq_update_peak_rate(q->elevator->elevator_data, rq);
-+
-+	bfq_remove_request(rq);
-+	elv_dispatch_sort(q, rq);
-+}
-+
-+static void __bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	BUG_ON(bfqq != bfqd->in_service_queue);
-+
-+	/*
-+	 * If this bfqq is shared between multiple processes, check
-+	 * to make sure that those processes are still issuing I/Os
-+	 * within the mean seek distance. If not, it may be time to
-+	 * break the queues apart again.
-+	 */
-+	if (bfq_bfqq_coop(bfqq) && BFQQ_SEEKY(bfqq))
-+		bfq_mark_bfqq_split_coop(bfqq);
-+
-+	if (RB_EMPTY_ROOT(&bfqq->sort_list)) {
-+		if (bfqq->dispatched == 0)
-+			/*
-+			 * Overloading budget_timeout field to store
-+			 * the time at which the queue remains with no
-+			 * backlog and no outstanding request; used by
-+			 * the weight-raising mechanism.
-+			 */
-+			bfqq->budget_timeout = jiffies;
-+
-+		bfq_del_bfqq_busy(bfqd, bfqq, true);
-+	} else {
-+		bfq_requeue_bfqq(bfqd, bfqq);
-+		/*
-+		 * Resort priority tree of potential close cooperators.
-+		 */
-+		bfq_pos_tree_add_move(bfqd, bfqq);
-+	}
-+
-+	/*
-+	 * All in-service entities must have been properly deactivated
-+	 * or requeued before executing the next function, which
-+	 * resets all in-service entites as no more in service.
-+	 */
-+	__bfq_bfqd_reset_in_service(bfqd);
-+}
-+
-+/**
-+ * __bfq_bfqq_recalc_budget - try to adapt the budget to the @bfqq behavior.
-+ * @bfqd: device data.
-+ * @bfqq: queue to update.
-+ * @reason: reason for expiration.
-+ *
-+ * Handle the feedback on @bfqq budget at queue expiration.
-+ * See the body for detailed comments.
-+ */
-+static void __bfq_bfqq_recalc_budget(struct bfq_data *bfqd,
-+				     struct bfq_queue *bfqq,
-+				     enum bfqq_expiration reason)
-+{
-+	struct request *next_rq;
-+	int budget, min_budget;
-+
-+	BUG_ON(bfqq != bfqd->in_service_queue);
-+
-+	min_budget = bfq_min_budget(bfqd);
-+
-+	if (bfqq->wr_coeff == 1)
-+		budget = bfqq->max_budget;
-+	else /*
-+	      * Use a constant, low budget for weight-raised queues,
-+	      * to help achieve a low latency. Keep it slightly higher
-+	      * than the minimum possible budget, to cause a little
-+	      * bit fewer expirations.
-+	      */
-+		budget = 2 * min_budget;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last budg %d, budg left %d",
-+		bfqq->entity.budget, bfq_bfqq_budget_left(bfqq));
-+	bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last max_budg %d, min budg %d",
-+		budget, bfq_min_budget(bfqd));
-+	bfq_log_bfqq(bfqd, bfqq, "recalc_budg: sync %d, seeky %d",
-+		bfq_bfqq_sync(bfqq), BFQQ_SEEKY(bfqd->in_service_queue));
-+
-+	if (bfq_bfqq_sync(bfqq) && bfqq->wr_coeff == 1) {
-+		switch (reason) {
-+		/*
-+		 * Caveat: in all the following cases we trade latency
-+		 * for throughput.
-+		 */
-+		case BFQ_BFQQ_TOO_IDLE:
-+			/*
-+			 * This is the only case where we may reduce
-+			 * the budget: if there is no request of the
-+			 * process still waiting for completion, then
-+			 * we assume (tentatively) that the timer has
-+			 * expired because the batch of requests of
-+			 * the process could have been served with a
-+			 * smaller budget.  Hence, betting that
-+			 * process will behave in the same way when it
-+			 * becomes backlogged again, we reduce its
-+			 * next budget.  As long as we guess right,
-+			 * this budget cut reduces the latency
-+			 * experienced by the process.
-+			 *
-+			 * However, if there are still outstanding
-+			 * requests, then the process may have not yet
-+			 * issued its next request just because it is
-+			 * still waiting for the completion of some of
-+			 * the still outstanding ones.  So in this
-+			 * subcase we do not reduce its budget, on the
-+			 * contrary we increase it to possibly boost
-+			 * the throughput, as discussed in the
-+			 * comments to the BUDGET_TIMEOUT case.
-+			 */
-+			if (bfqq->dispatched > 0) /* still outstanding reqs */
-+				budget = min(budget * 2, bfqd->bfq_max_budget);
-+			else {
-+				if (budget > 5 * min_budget)
-+					budget -= 4 * min_budget;
-+				else
-+					budget = min_budget;
-+			}
-+			break;
-+		case BFQ_BFQQ_BUDGET_TIMEOUT:
-+			/*
-+			 * We double the budget here because it gives
-+			 * the chance to boost the throughput if this
-+			 * is not a seeky process (and has bumped into
-+			 * this timeout because of, e.g., ZBR).
-+			 */
-+			budget = min(budget * 2, bfqd->bfq_max_budget);
-+			break;
-+		case BFQ_BFQQ_BUDGET_EXHAUSTED:
-+			/*
-+			 * The process still has backlog, and did not
-+			 * let either the budget timeout or the disk
-+			 * idling timeout expire. Hence it is not
-+			 * seeky, has a short thinktime and may be
-+			 * happy with a higher budget too. So
-+			 * definitely increase the budget of this good
-+			 * candidate to boost the disk throughput.
-+			 */
-+			budget = min(budget * 4, bfqd->bfq_max_budget);
-+			break;
-+		case BFQ_BFQQ_NO_MORE_REQUESTS:
-+			/*
-+			 * For queues that expire for this reason, it
-+			 * is particularly important to keep the
-+			 * budget close to the actual service they
-+			 * need. Doing so reduces the timestamp
-+			 * misalignment problem described in the
-+			 * comments in the body of
-+			 * __bfq_activate_entity. In fact, suppose
-+			 * that a queue systematically expires for
-+			 * BFQ_BFQQ_NO_MORE_REQUESTS and presents a
-+			 * new request in time to enjoy timestamp
-+			 * back-shifting. The larger the budget of the
-+			 * queue is with respect to the service the
-+			 * queue actually requests in each service
-+			 * slot, the more times the queue can be
-+			 * reactivated with the same virtual finish
-+			 * time. It follows that, even if this finish
-+			 * time is pushed to the system virtual time
-+			 * to reduce the consequent timestamp
-+			 * misalignment, the queue unjustly enjoys for
-+			 * many re-activations a lower finish time
-+			 * than all newly activated queues.
-+			 *
-+			 * The service needed by bfqq is measured
-+			 * quite precisely by bfqq->entity.service.
-+			 * Since bfqq does not enjoy device idling,
-+			 * bfqq->entity.service is equal to the number
-+			 * of sectors that the process associated with
-+			 * bfqq requested to read/write before waiting
-+			 * for request completions, or blocking for
-+			 * other reasons.
-+			 */
-+			budget = max_t(int, bfqq->entity.service, min_budget);
-+			break;
-+		default:
-+			return;
-+		}
-+	} else if (!bfq_bfqq_sync(bfqq))
-+		/*
-+		 * Async queues get always the maximum possible
-+		 * budget, as for them we do not care about latency
-+		 * (in addition, their ability to dispatch is limited
-+		 * by the charging factor).
-+		 */
-+		budget = bfqd->bfq_max_budget;
-+
-+	bfqq->max_budget = budget;
-+
-+	if (bfqd->budgets_assigned >= bfq_stats_min_budgets &&
-+	    !bfqd->bfq_user_max_budget)
-+		bfqq->max_budget = min(bfqq->max_budget, bfqd->bfq_max_budget);
-+
-+	/*
-+	 * If there is still backlog, then assign a new budget, making
-+	 * sure that it is large enough for the next request.  Since
-+	 * the finish time of bfqq must be kept in sync with the
-+	 * budget, be sure to call __bfq_bfqq_expire() *after* this
-+	 * update.
-+	 *
-+	 * If there is no backlog, then no need to update the budget;
-+	 * it will be updated on the arrival of a new request.
-+	 */
-+	next_rq = bfqq->next_rq;
-+	if (next_rq) {
-+		BUG_ON(reason == BFQ_BFQQ_TOO_IDLE ||
-+		       reason == BFQ_BFQQ_NO_MORE_REQUESTS);
-+		bfqq->entity.budget = max_t(unsigned long, bfqq->max_budget,
-+					    bfq_serv_to_charge(next_rq, bfqq));
-+		BUG_ON(!bfq_bfqq_busy(bfqq));
-+		BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list));
-+	}
-+
-+	bfq_log_bfqq(bfqd, bfqq, "head sect: %u, new budget %d",
-+			next_rq ? blk_rq_sectors(next_rq) : 0,
-+			bfqq->entity.budget);
-+}
-+
-+/*
-+ * Return true if the process associated with bfqq is "slow". The slow
-+ * flag is used, in addition to the budget timeout, to reduce the
-+ * amount of service provided to seeky processes, and thus reduce
-+ * their chances to lower the throughput. More details in the comments
-+ * on the function bfq_bfqq_expire().
-+ *
-+ * An important observation is in order: as discussed in the comments
-+ * on the function bfq_update_peak_rate(), with devices with internal
-+ * queues, it is hard if ever possible to know when and for how long
-+ * an I/O request is processed by the device (apart from the trivial
-+ * I/O pattern where a new request is dispatched only after the
-+ * previous one has been completed). This makes it hard to evaluate
-+ * the real rate at which the I/O requests of each bfq_queue are
-+ * served.  In fact, for an I/O scheduler like BFQ, serving a
-+ * bfq_queue means just dispatching its requests during its service
-+ * slot (i.e., until the budget of the queue is exhausted, or the
-+ * queue remains idle, or, finally, a timeout fires). But, during the
-+ * service slot of a bfq_queue, around 100 ms at most, the device may
-+ * be even still processing requests of bfq_queues served in previous
-+ * service slots. On the opposite end, the requests of the in-service
-+ * bfq_queue may be completed after the service slot of the queue
-+ * finishes.
-+ *
-+ * Anyway, unless more sophisticated solutions are used
-+ * (where possible), the sum of the sizes of the requests dispatched
-+ * during the service slot of a bfq_queue is probably the only
-+ * approximation available for the service received by the bfq_queue
-+ * during its service slot. And this sum is the quantity used in this
-+ * function to evaluate the I/O speed of a process.
-+ */
-+static bool bfq_bfqq_is_slow(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+				 bool compensate, enum bfqq_expiration reason,
-+				 unsigned long *delta_ms)
-+{
-+	ktime_t delta_ktime;
-+	u32 delta_usecs;
-+	bool slow = BFQQ_SEEKY(bfqq); /* if delta too short, use seekyness */
-+
-+	if (!bfq_bfqq_sync(bfqq))
-+		return false;
-+
-+	if (compensate)
-+		delta_ktime = bfqd->last_idling_start;
-+	else
-+		delta_ktime = ktime_get();
-+	delta_ktime = ktime_sub(delta_ktime, bfqd->last_budget_start);
-+	delta_usecs = ktime_to_us(delta_ktime);
-+
-+	/* don't use too short time intervals */
-+	if (delta_usecs < 1000) {
-+		if (blk_queue_nonrot(bfqd->queue))
-+			 /*
-+			  * give same worst-case guarantees as idling
-+			  * for seeky
-+			  */
-+			*delta_ms = BFQ_MIN_TT / NSEC_PER_MSEC;
-+		else /* charge at least one seek */
-+			*delta_ms = bfq_slice_idle / NSEC_PER_MSEC;
-+
-+		bfq_log(bfqd, "bfq_bfqq_is_slow: too short %u", delta_usecs);
-+
-+		return slow;
-+	}
-+
-+	*delta_ms = delta_usecs / USEC_PER_MSEC;
-+
-+	/*
-+	 * Use only long (> 20ms) intervals to filter out excessive
-+	 * spikes in service rate estimation.
-+	 */
-+	if (delta_usecs > 20000) {
-+		/*
-+		 * Caveat for rotational devices: processes doing I/O
-+		 * in the slower disk zones tend to be slow(er) even
-+		 * if not seeky. In this respect, the estimated peak
-+		 * rate is likely to be an average over the disk
-+		 * surface. Accordingly, to not be too harsh with
-+		 * unlucky processes, a process is deemed slow only if
-+		 * its rate has been lower than half of the estimated
-+		 * peak rate.
-+		 */
-+		slow = bfqq->entity.service < bfqd->bfq_max_budget / 2;
-+		bfq_log(bfqd, "bfq_bfqq_is_slow: relative rate %d/%d",
-+			bfqq->entity.service, bfqd->bfq_max_budget);
-+	}
-+
-+	bfq_log_bfqq(bfqd, bfqq, "bfq_bfqq_is_slow: slow %d", slow);
-+
-+	return slow;
-+}
-+
-+/*
-+ * To be deemed as soft real-time, an application must meet two
-+ * requirements. First, the application must not require an average
-+ * bandwidth higher than the approximate bandwidth required to playback or
-+ * record a compressed high-definition video.
-+ * The next function is invoked on the completion of the last request of a
-+ * batch, to compute the next-start time instant, soft_rt_next_start, such
-+ * that, if the next request of the application does not arrive before
-+ * soft_rt_next_start, then the above requirement on the bandwidth is met.
-+ *
-+ * The second requirement is that the request pattern of the application is
-+ * isochronous, i.e., that, after issuing a request or a batch of requests,
-+ * the application stops issuing new requests until all its pending requests
-+ * have been completed. After that, the application may issue a new batch,
-+ * and so on.
-+ * For this reason the next function is invoked to compute
-+ * soft_rt_next_start only for applications that meet this requirement,
-+ * whereas soft_rt_next_start is set to infinity for applications that do
-+ * not.
-+ *
-+ * Unfortunately, even a greedy application may happen to behave in an
-+ * isochronous way if the CPU load is high. In fact, the application may
-+ * stop issuing requests while the CPUs are busy serving other processes,
-+ * then restart, then stop again for a while, and so on. In addition, if
-+ * the disk achieves a low enough throughput with the request pattern
-+ * issued by the application (e.g., because the request pattern is random
-+ * and/or the device is slow), then the application may meet the above
-+ * bandwidth requirement too. To prevent such a greedy application to be
-+ * deemed as soft real-time, a further rule is used in the computation of
-+ * soft_rt_next_start: soft_rt_next_start must be higher than the current
-+ * time plus the maximum time for which the arrival of a request is waited
-+ * for when a sync queue becomes idle, namely bfqd->bfq_slice_idle.
-+ * This filters out greedy applications, as the latter issue instead their
-+ * next request as soon as possible after the last one has been completed
-+ * (in contrast, when a batch of requests is completed, a soft real-time
-+ * application spends some time processing data).
-+ *
-+ * Unfortunately, the last filter may easily generate false positives if
-+ * only bfqd->bfq_slice_idle is used as a reference time interval and one
-+ * or both the following cases occur:
-+ * 1) HZ is so low that the duration of a jiffy is comparable to or higher
-+ *    than bfqd->bfq_slice_idle. This happens, e.g., on slow devices with
-+ *    HZ=100.
-+ * 2) jiffies, instead of increasing at a constant rate, may stop increasing
-+ *    for a while, then suddenly 'jump' by several units to recover the lost
-+ *    increments. This seems to happen, e.g., inside virtual machines.
-+ * To address this issue, we do not use as a reference time interval just
-+ * bfqd->bfq_slice_idle, but bfqd->bfq_slice_idle plus a few jiffies. In
-+ * particular we add the minimum number of jiffies for which the filter
-+ * seems to be quite precise also in embedded systems and KVM/QEMU virtual
-+ * machines.
-+ */
-+static unsigned long bfq_bfqq_softrt_next_start(struct bfq_data *bfqd,
-+						struct bfq_queue *bfqq)
-+{
-+	bfq_log_bfqq(bfqd, bfqq,
-+"softrt_next_start: service_blkg %lu soft_rate %u sects/sec interval %u",
-+		     bfqq->service_from_backlogged,
-+		     bfqd->bfq_wr_max_softrt_rate,
-+		     jiffies_to_msecs(HZ * bfqq->service_from_backlogged /
-+				      bfqd->bfq_wr_max_softrt_rate));
-+
-+	return max(bfqq->last_idle_bklogged +
-+		   HZ * bfqq->service_from_backlogged /
-+		   bfqd->bfq_wr_max_softrt_rate,
-+		   jiffies + nsecs_to_jiffies(bfqq->bfqd->bfq_slice_idle) + 4);
-+}
-+
-+/*
-+ * Return the farthest future time instant according to jiffies
-+ * macros.
-+ */
-+static unsigned long bfq_greatest_from_now(void)
-+{
-+	return jiffies + MAX_JIFFY_OFFSET;
-+}
-+
-+/*
-+ * Return the farthest past time instant according to jiffies
-+ * macros.
-+ */
-+static unsigned long bfq_smallest_from_now(void)
-+{
-+	return jiffies - MAX_JIFFY_OFFSET;
-+}
-+
-+/**
-+ * bfq_bfqq_expire - expire a queue.
-+ * @bfqd: device owning the queue.
-+ * @bfqq: the queue to expire.
-+ * @compensate: if true, compensate for the time spent idling.
-+ * @reason: the reason causing the expiration.
-+ *
-+ * If the process associated with bfqq does slow I/O (e.g., because it
-+ * issues random requests), we charge bfqq with the time it has been
-+ * in service instead of the service it has received (see
-+ * bfq_bfqq_charge_time for details on how this goal is achieved). As
-+ * a consequence, bfqq will typically get higher timestamps upon
-+ * reactivation, and hence it will be rescheduled as if it had
-+ * received more service than what it has actually received. In the
-+ * end, bfqq receives less service in proportion to how slowly its
-+ * associated process consumes its budgets (and hence how seriously it
-+ * tends to lower the throughput). In addition, this time-charging
-+ * strategy guarantees time fairness among slow processes. In
-+ * contrast, if the process associated with bfqq is not slow, we
-+ * charge bfqq exactly with the service it has received.
-+ *
-+ * Charging time to the first type of queues and the exact service to
-+ * the other has the effect of using the WF2Q+ policy to schedule the
-+ * former on a timeslice basis, without violating service domain
-+ * guarantees among the latter.
-+ */
-+static void bfq_bfqq_expire(struct bfq_data *bfqd,
-+			    struct bfq_queue *bfqq,
-+			    bool compensate,
-+			    enum bfqq_expiration reason)
-+{
-+	bool slow;
-+	unsigned long delta = 0;
-+	struct bfq_entity *entity = &bfqq->entity;
-+	int ref;
-+
-+	BUG_ON(bfqq != bfqd->in_service_queue);
-+
-+	/*
-+	 * Check whether the process is slow (see bfq_bfqq_is_slow).
-+	 */
-+	slow = bfq_bfqq_is_slow(bfqd, bfqq, compensate, reason, &delta);
-+
-+	/*
-+	 * Increase service_from_backlogged before next statement,
-+	 * because the possible next invocation of
-+	 * bfq_bfqq_charge_time would likely inflate
-+	 * entity->service. In contrast, service_from_backlogged must
-+	 * contain real service, to enable the soft real-time
-+	 * heuristic to correctly compute the bandwidth consumed by
-+	 * bfqq.
-+	 */
-+	bfqq->service_from_backlogged += entity->service;
-+
-+	/*
-+	 * As above explained, charge slow (typically seeky) and
-+	 * timed-out queues with the time and not the service
-+	 * received, to favor sequential workloads.
-+	 *
-+	 * Processes doing I/O in the slower disk zones will tend to
-+	 * be slow(er) even if not seeky. Therefore, since the
-+	 * estimated peak rate is actually an average over the disk
-+	 * surface, these processes may timeout just for bad luck. To
-+	 * avoid punishing them, do not charge time to processes that
-+	 * succeeded in consuming at least 2/3 of their budget. This
-+	 * allows BFQ to preserve enough elasticity to still perform
-+	 * bandwidth, and not time, distribution with little unlucky
-+	 * or quasi-sequential processes.
-+	 */
-+	if (bfqq->wr_coeff == 1 &&
-+	    (slow ||
-+	     (reason == BFQ_BFQQ_BUDGET_TIMEOUT &&
-+	      bfq_bfqq_budget_left(bfqq) >=  entity->budget / 3)))
-+		bfq_bfqq_charge_time(bfqd, bfqq, delta);
-+
-+	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
-+
-+	if (reason == BFQ_BFQQ_TOO_IDLE &&
-+	    entity->service <= 2 * entity->budget / 10)
-+		bfq_clear_bfqq_IO_bound(bfqq);
-+
-+	if (bfqd->low_latency && bfqq->wr_coeff == 1)
-+		bfqq->last_wr_start_finish = jiffies;
-+
-+	if (bfqd->low_latency && bfqd->bfq_wr_max_softrt_rate > 0 &&
-+	    RB_EMPTY_ROOT(&bfqq->sort_list)) {
-+		/*
-+		 * If we get here, and there are no outstanding
-+		 * requests, then the request pattern is isochronous
-+		 * (see the comments on the function
-+		 * bfq_bfqq_softrt_next_start()). Thus we can compute
-+		 * soft_rt_next_start. If, instead, the queue still
-+		 * has outstanding requests, then we have to wait for
-+		 * the completion of all the outstanding requests to
-+		 * discover whether the request pattern is actually
-+		 * isochronous.
-+		 */
-+		BUG_ON(bfqd->busy_queues < 1);
-+		if (bfqq->dispatched == 0) {
-+			bfqq->soft_rt_next_start =
-+				bfq_bfqq_softrt_next_start(bfqd, bfqq);
-+			bfq_log_bfqq(bfqd, bfqq, "new soft_rt_next %lu",
-+				     bfqq->soft_rt_next_start);
-+		} else {
-+			/*
-+			 * The application is still waiting for the
-+			 * completion of one or more requests:
-+			 * prevent it from possibly being incorrectly
-+			 * deemed as soft real-time by setting its
-+			 * soft_rt_next_start to infinity. In fact,
-+			 * without this assignment, the application
-+			 * would be incorrectly deemed as soft
-+			 * real-time if:
-+			 * 1) it issued a new request before the
-+			 *    completion of all its in-flight
-+			 *    requests, and
-+			 * 2) at that time, its soft_rt_next_start
-+			 *    happened to be in the past.
-+			 */
-+			bfqq->soft_rt_next_start =
-+				bfq_greatest_from_now();
-+			/*
-+			 * Schedule an update of soft_rt_next_start to when
-+			 * the task may be discovered to be isochronous.
-+			 */
-+			bfq_mark_bfqq_softrt_update(bfqq);
-+		}
-+	}
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+		"expire (%d, slow %d, num_disp %d, short_ttime %d, weight %d)",
-+		     reason, slow, bfqq->dispatched,
-+		     bfq_bfqq_has_short_ttime(bfqq), entity->weight);
-+
-+	/*
-+	 * Increase, decrease or leave budget unchanged according to
-+	 * reason.
-+	 */
-+	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
-+	__bfq_bfqq_recalc_budget(bfqd, bfqq, reason);
-+	BUG_ON(bfqq->next_rq == NULL &&
-+	       bfqq->entity.budget < bfqq->entity.service);
-+	ref = bfqq->ref;
-+	__bfq_bfqq_expire(bfqd, bfqq);
-+
-+	BUG_ON(ref > 1 &&
-+	       !bfq_bfqq_busy(bfqq) && reason == BFQ_BFQQ_BUDGET_EXHAUSTED &&
-+		!bfq_class_idle(bfqq));
-+
-+	/* mark bfqq as waiting a request only if a bic still points to it */
-+	if (ref > 1 && !bfq_bfqq_busy(bfqq) &&
-+	    reason != BFQ_BFQQ_BUDGET_TIMEOUT &&
-+	    reason != BFQ_BFQQ_BUDGET_EXHAUSTED)
-+		bfq_mark_bfqq_non_blocking_wait_rq(bfqq);
-+}
-+
-+/*
-+ * Budget timeout is not implemented through a dedicated timer, but
-+ * just checked on request arrivals and completions, as well as on
-+ * idle timer expirations.
-+ */
-+static bool bfq_bfqq_budget_timeout(struct bfq_queue *bfqq)
-+{
-+	return time_is_before_eq_jiffies(bfqq->budget_timeout);
-+}
-+
-+/*
-+ * If we expire a queue that is actively waiting (i.e., with the
-+ * device idled) for the arrival of a new request, then we may incur
-+ * the timestamp misalignment problem described in the body of the
-+ * function __bfq_activate_entity. Hence we return true only if this
-+ * condition does not hold, or if the queue is slow enough to deserve
-+ * only to be kicked off for preserving a high throughput.
-+ */
-+static bool bfq_may_expire_for_budg_timeout(struct bfq_queue *bfqq)
-+{
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		"may_budget_timeout: wait_request %d left %d timeout %d",
-+		bfq_bfqq_wait_request(bfqq),
-+			bfq_bfqq_budget_left(bfqq) >=  bfqq->entity.budget / 3,
-+		bfq_bfqq_budget_timeout(bfqq));
-+
-+	return (!bfq_bfqq_wait_request(bfqq) ||
-+		bfq_bfqq_budget_left(bfqq) >=  bfqq->entity.budget / 3)
-+		&&
-+		bfq_bfqq_budget_timeout(bfqq);
-+}
-+
-+/*
-+ * For a queue that becomes empty, device idling is allowed only if
-+ * this function returns true for that queue. As a consequence, since
-+ * device idling plays a critical role for both throughput boosting
-+ * and service guarantees, the return value of this function plays a
-+ * critical role as well.
-+ *
-+ * In a nutshell, this function returns true only if idling is
-+ * beneficial for throughput or, even if detrimental for throughput,
-+ * idling is however necessary to preserve service guarantees (low
-+ * latency, desired throughput distribution, ...). In particular, on
-+ * NCQ-capable devices, this function tries to return false, so as to
-+ * help keep the drives' internal queues full, whenever this helps the
-+ * device boost the throughput without causing any service-guarantee
-+ * issue.
-+ *
-+ * In more detail, the return value of this function is obtained by,
-+ * first, computing a number of boolean variables that take into
-+ * account throughput and service-guarantee issues, and, then,
-+ * combining these variables in a logical expression. Most of the
-+ * issues taken into account are not trivial. We discuss these issues
-+ * while introducing the variables.
-+ */
-+static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq)
-+{
-+	struct bfq_data *bfqd = bfqq->bfqd;
-+	bool rot_without_queueing =
-+		!blk_queue_nonrot(bfqd->queue) && !bfqd->hw_tag,
-+		bfqq_sequential_and_IO_bound,
-+		idling_boosts_thr, idling_boosts_thr_without_issues,
-+		idling_needed_for_service_guarantees,
-+		asymmetric_scenario;
-+
-+	if (bfqd->strict_guarantees)
-+		return true;
-+
-+	/*
-+	 * Idling is performed only if slice_idle > 0. In addition, we
-+	 * do not idle if
-+	 * (a) bfqq is async
-+	 * (b) bfqq is in the idle io prio class: in this case we do
-+	 * not idle because we want to minimize the bandwidth that
-+	 * queues in this class can steal to higher-priority queues
-+	 */
-+	if (bfqd->bfq_slice_idle == 0 || !bfq_bfqq_sync(bfqq) ||
-+	   bfq_class_idle(bfqq))
-+		return false;
-+
-+	bfqq_sequential_and_IO_bound = !BFQQ_SEEKY(bfqq) &&
-+		bfq_bfqq_IO_bound(bfqq) && bfq_bfqq_has_short_ttime(bfqq);
-+	/*
-+	 * The next variable takes into account the cases where idling
-+	 * boosts the throughput.
-+	 *
-+	 * The value of the variable is computed considering, first, that
-+	 * idling is virtually always beneficial for the throughput if:
-+	 * (a) the device is not NCQ-capable and rotational, or
-+	 * (b) regardless of the presence of NCQ, the device is rotational and
-+	 *     the request pattern for bfqq is I/O-bound and sequential, or
-+	 * (c) regardless of whether it is rotational, the device is
-+	 *     not NCQ-capable and the request pattern for bfqq is
-+	 *     I/O-bound and sequential.
-+	 *
-+	 * Secondly, and in contrast to the above item (b), idling an
-+	 * NCQ-capable flash-based device would not boost the
-+	 * throughput even with sequential I/O; rather it would lower
-+	 * the throughput in proportion to how fast the device
-+	 * is. Accordingly, the next variable is true if any of the
-+	 * above conditions (a), (b) or (c) is true, and, in
-+	 * particular, happens to be false if bfqd is an NCQ-capable
-+	 * flash-based device.
-+	 */
-+	idling_boosts_thr = rot_without_queueing ||
-+		((!blk_queue_nonrot(bfqd->queue) || !bfqd->hw_tag) &&
-+		 bfqq_sequential_and_IO_bound);
-+
-+	/*
-+	 * The value of the next variable,
-+	 * idling_boosts_thr_without_issues, is equal to that of
-+	 * idling_boosts_thr, unless a special case holds. In this
-+	 * special case, described below, idling may cause problems to
-+	 * weight-raised queues.
-+	 *
-+	 * When the request pool is saturated (e.g., in the presence
-+	 * of write hogs), if the processes associated with
-+	 * non-weight-raised queues ask for requests at a lower rate,
-+	 * then processes associated with weight-raised queues have a
-+	 * higher probability to get a request from the pool
-+	 * immediately (or at least soon) when they need one. Thus
-+	 * they have a higher probability to actually get a fraction
-+	 * of the device throughput proportional to their high
-+	 * weight. This is especially true with NCQ-capable drives,
-+	 * which enqueue several requests in advance, and further
-+	 * reorder internally-queued requests.
-+	 *
-+	 * For this reason, we force to false the value of
-+	 * idling_boosts_thr_without_issues if there are weight-raised
-+	 * busy queues. In this case, and if bfqq is not weight-raised,
-+	 * this guarantees that the device is not idled for bfqq (if,
-+	 * instead, bfqq is weight-raised, then idling will be
-+	 * guaranteed by another variable, see below). Combined with
-+	 * the timestamping rules of BFQ (see [1] for details), this
-+	 * behavior causes bfqq, and hence any sync non-weight-raised
-+	 * queue, to get a lower number of requests served, and thus
-+	 * to ask for a lower number of requests from the request
-+	 * pool, before the busy weight-raised queues get served
-+	 * again. This often mitigates starvation problems in the
-+	 * presence of heavy write workloads and NCQ, thereby
-+	 * guaranteeing a higher application and system responsiveness
-+	 * in these hostile scenarios.
-+	 */
-+	idling_boosts_thr_without_issues = idling_boosts_thr &&
-+		bfqd->wr_busy_queues == 0;
-+
-+	/*
-+	 * There is then a case where idling must be performed not
-+	 * for throughput concerns, but to preserve service
-+	 * guarantees.
-+	 *
-+	 * To introduce this case, we can note that allowing the drive
-+	 * to enqueue more than one request at a time, and hence
-+	 * delegating de facto final scheduling decisions to the
-+	 * drive's internal scheduler, entails loss of control on the
-+	 * actual request service order. In particular, the critical
-+	 * situation is when requests from different processes happen
-+	 * to be present, at the same time, in the internal queue(s)
-+	 * of the drive. In such a situation, the drive, by deciding
-+	 * the service order of the internally-queued requests, does
-+	 * determine also the actual throughput distribution among
-+	 * these processes. But the drive typically has no notion or
-+	 * concern about per-process throughput distribution, and
-+	 * makes its decisions only on a per-request basis. Therefore,
-+	 * the service distribution enforced by the drive's internal
-+	 * scheduler is likely to coincide with the desired
-+	 * device-throughput distribution only in a completely
-+	 * symmetric scenario where:
-+	 * (i)  each of these processes must get the same throughput as
-+	 *      the others;
-+	 * (ii) all these processes have the same I/O pattern
-+	 *      (either sequential or random).
-+	 * In fact, in such a scenario, the drive will tend to treat
-+	 * the requests of each of these processes in about the same
-+	 * way as the requests of the others, and thus to provide
-+	 * each of these processes with about the same throughput
-+	 * (which is exactly the desired throughput distribution). In
-+	 * contrast, in any asymmetric scenario, device idling is
-+	 * certainly needed to guarantee that bfqq receives its
-+	 * assigned fraction of the device throughput (see [1] for
-+	 * details).
-+	 *
-+	 * We address this issue by controlling, actually, only the
-+	 * symmetry sub-condition (i), i.e., provided that
-+	 * sub-condition (i) holds, idling is not performed,
-+	 * regardless of whether sub-condition (ii) holds. In other
-+	 * words, only if sub-condition (i) holds, then idling is
-+	 * allowed, and the device tends to be prevented from queueing
-+	 * many requests, possibly of several processes. The reason
-+	 * for not controlling also sub-condition (ii) is that we
-+	 * exploit preemption to preserve guarantees in case of
-+	 * symmetric scenarios, even if (ii) does not hold, as
-+	 * explained in the next two paragraphs.
-+	 *
-+	 * Even if a queue, say Q, is expired when it remains idle, Q
-+	 * can still preempt the new in-service queue if the next
-+	 * request of Q arrives soon (see the comments on
-+	 * bfq_bfqq_update_budg_for_activation). If all queues and
-+	 * groups have the same weight, this form of preemption,
-+	 * combined with the hole-recovery heuristic described in the
-+	 * comments on function bfq_bfqq_update_budg_for_activation,
-+	 * are enough to preserve a correct bandwidth distribution in
-+	 * the mid term, even without idling. In fact, even if not
-+	 * idling allows the internal queues of the device to contain
-+	 * many requests, and thus to reorder requests, we can rather
-+	 * safely assume that the internal scheduler still preserves a
-+	 * minimum of mid-term fairness. The motivation for using
-+	 * preemption instead of idling is that, by not idling,
-+	 * service guarantees are preserved without minimally
-+	 * sacrificing throughput. In other words, both a high
-+	 * throughput and its desired distribution are obtained.
-+	 *
-+	 * More precisely, this preemption-based, idleless approach
-+	 * provides fairness in terms of IOPS, and not sectors per
-+	 * second. This can be seen with a simple example. Suppose
-+	 * that there are two queues with the same weight, but that
-+	 * the first queue receives requests of 8 sectors, while the
-+	 * second queue receives requests of 1024 sectors. In
-+	 * addition, suppose that each of the two queues contains at
-+	 * most one request at a time, which implies that each queue
-+	 * always remains idle after it is served. Finally, after
-+	 * remaining idle, each queue receives very quickly a new
-+	 * request. It follows that the two queues are served
-+	 * alternatively, preempting each other if needed. This
-+	 * implies that, although both queues have the same weight,
-+	 * the queue with large requests receives a service that is
-+	 * 1024/8 times as high as the service received by the other
-+	 * queue.
-+	 *
-+	 * On the other hand, device idling is performed, and thus
-+	 * pure sector-domain guarantees are provided, for the
-+	 * following queues, which are likely to need stronger
-+	 * throughput guarantees: weight-raised queues, and queues
-+	 * with a higher weight than other queues. When such queues
-+	 * are active, sub-condition (i) is false, which triggers
-+	 * device idling.
-+	 *
-+	 * According to the above considerations, the next variable is
-+	 * true (only) if sub-condition (i) holds. To compute the
-+	 * value of this variable, we not only use the return value of
-+	 * the function bfq_symmetric_scenario(), but also check
-+	 * whether bfqq is being weight-raised, because
-+	 * bfq_symmetric_scenario() does not take into account also
-+	 * weight-raised queues (see comments on
-+	 * bfq_weights_tree_add()).
-+	 *
-+	 * As a side note, it is worth considering that the above
-+	 * device-idling countermeasures may however fail in the
-+	 * following unlucky scenario: if idling is (correctly)
-+	 * disabled in a time period during which all symmetry
-+	 * sub-conditions hold, and hence the device is allowed to
-+	 * enqueue many requests, but at some later point in time some
-+	 * sub-condition stops to hold, then it may become impossible
-+	 * to let requests be served in the desired order until all
-+	 * the requests already queued in the device have been served.
-+	 */
-+	asymmetric_scenario = bfqq->wr_coeff > 1 ||
-+		!bfq_symmetric_scenario(bfqd);
-+
-+	/*
-+	 * Finally, there is a case where maximizing throughput is the
-+	 * best choice even if it may cause unfairness toward
-+	 * bfqq. Such a case is when bfqq became active in a burst of
-+	 * queue activations. Queues that became active during a large
-+	 * burst benefit only from throughput, as discussed in the
-+	 * comments on bfq_handle_burst. Thus, if bfqq became active
-+	 * in a burst and not idling the device maximizes throughput,
-+	 * then the device must no be idled, because not idling the
-+	 * device provides bfqq and all other queues in the burst with
-+	 * maximum benefit. Combining this and the above case, we can
-+	 * now establish when idling is actually needed to preserve
-+	 * service guarantees.
-+	 */
-+	idling_needed_for_service_guarantees =
-+		asymmetric_scenario && !bfq_bfqq_in_large_burst(bfqq);
-+
-+	/*
-+	 * We have now all the components we need to compute the
-+	 * return value of the function, which is true only if idling
-+	 * either boosts the throughput (without issues), or is
-+	 * necessary to preserve service guarantees.
-+	 */
-+	bfq_log_bfqq(bfqd, bfqq, "may_idle: sync %d idling_boosts_thr %d",
-+		     bfq_bfqq_sync(bfqq), idling_boosts_thr);
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+		     "may_idle: wr_busy %d boosts %d IO-bound %d guar %d",
-+		     bfqd->wr_busy_queues,
-+		     idling_boosts_thr_without_issues,
-+		     bfq_bfqq_IO_bound(bfqq),
-+		     idling_needed_for_service_guarantees);
-+
-+	return idling_boosts_thr_without_issues ||
-+		idling_needed_for_service_guarantees;
-+}
-+
-+/*
-+ * If the in-service queue is empty but the function bfq_bfqq_may_idle
-+ * returns true, then:
-+ * 1) the queue must remain in service and cannot be expired, and
-+ * 2) the device must be idled to wait for the possible arrival of a new
-+ *    request for the queue.
-+ * See the comments on the function bfq_bfqq_may_idle for the reasons
-+ * why performing device idling is the best choice to boost the throughput
-+ * and preserve service guarantees when bfq_bfqq_may_idle itself
-+ * returns true.
-+ */
-+static bool bfq_bfqq_must_idle(struct bfq_queue *bfqq)
-+{
-+	return RB_EMPTY_ROOT(&bfqq->sort_list) && bfq_bfqq_may_idle(bfqq);
-+}
-+
-+/*
-+ * Select a queue for service.  If we have a current queue in service,
-+ * check whether to continue servicing it, or retrieve and set a new one.
-+ */
-+static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd)
-+{
-+	struct bfq_queue *bfqq;
-+	struct request *next_rq;
-+	enum bfqq_expiration reason = BFQ_BFQQ_BUDGET_TIMEOUT;
-+
-+	bfqq = bfqd->in_service_queue;
-+	if (!bfqq)
-+		goto new_queue;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "select_queue: already in-service queue");
-+
-+	if (bfq_may_expire_for_budg_timeout(bfqq) &&
-+	    !hrtimer_active(&bfqd->idle_slice_timer) &&
-+	    !bfq_bfqq_must_idle(bfqq))
-+		goto expire;
-+
-+check_queue:
-+	/*
-+	 * This loop is rarely executed more than once. Even when it
-+	 * happens, it is much more convenient to re-execute this loop
-+	 * than to return NULL and trigger a new dispatch to get a
-+	 * request served.
-+	 */
-+	next_rq = bfqq->next_rq;
-+	/*
-+	 * If bfqq has requests queued and it has enough budget left to
-+	 * serve them, keep the queue, otherwise expire it.
-+	 */
-+	if (next_rq) {
-+		BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list));
-+
-+		if (bfq_serv_to_charge(next_rq, bfqq) >
-+			bfq_bfqq_budget_left(bfqq)) {
-+			/*
-+			 * Expire the queue for budget exhaustion,
-+			 * which makes sure that the next budget is
-+			 * enough to serve the next request, even if
-+			 * it comes from the fifo expired path.
-+			 */
-+			reason = BFQ_BFQQ_BUDGET_EXHAUSTED;
-+			goto expire;
-+		} else {
-+			/*
-+			 * The idle timer may be pending because we may
-+			 * not disable disk idling even when a new request
-+			 * arrives.
-+			 */
-+			if (bfq_bfqq_wait_request(bfqq)) {
-+				BUG_ON(!hrtimer_active(&bfqd->idle_slice_timer));
-+				/*
-+				 * If we get here: 1) at least a new request
-+				 * has arrived but we have not disabled the
-+				 * timer because the request was too small,
-+				 * 2) then the block layer has unplugged
-+				 * the device, causing the dispatch to be
-+				 * invoked.
-+				 *
-+				 * Since the device is unplugged, now the
-+				 * requests are probably large enough to
-+				 * provide a reasonable throughput.
-+				 * So we disable idling.
-+				 */
-+				bfq_clear_bfqq_wait_request(bfqq);
-+				hrtimer_try_to_cancel(&bfqd->idle_slice_timer);
-+				bfqg_stats_update_idle_time(bfqq_group(bfqq));
-+			}
-+			goto keep_queue;
-+		}
-+	}
-+
-+	/*
-+	 * No requests pending. However, if the in-service queue is idling
-+	 * for a new request, or has requests waiting for a completion and
-+	 * may idle after their completion, then keep it anyway.
-+	 */
-+	if (hrtimer_active(&bfqd->idle_slice_timer) ||
-+	    (bfqq->dispatched != 0 && bfq_bfqq_may_idle(bfqq))) {
-+		bfqq = NULL;
-+		goto keep_queue;
-+	}
-+
-+	reason = BFQ_BFQQ_NO_MORE_REQUESTS;
-+expire:
-+	bfq_bfqq_expire(bfqd, bfqq, false, reason);
-+new_queue:
-+	bfqq = bfq_set_in_service_queue(bfqd);
-+	if (bfqq) {
-+		bfq_log_bfqq(bfqd, bfqq, "select_queue: checking new queue");
-+		goto check_queue;
-+	}
-+keep_queue:
-+	if (bfqq)
-+		bfq_log_bfqq(bfqd, bfqq, "select_queue: returned this queue");
-+	else
-+		bfq_log(bfqd, "select_queue: no queue returned");
-+
-+	return bfqq;
-+}
-+
-+static void bfq_update_wr_data(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+
-+	if (bfqq->wr_coeff > 1) { /* queue is being weight-raised */
-+		BUG_ON(bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time &&
-+		       time_is_after_jiffies(bfqq->last_wr_start_finish));
-+
-+		bfq_log_bfqq(bfqd, bfqq,
-+			"raising period dur %u/%u msec, old coeff %u, w %d(%d)",
-+			jiffies_to_msecs(jiffies - bfqq->last_wr_start_finish),
-+			jiffies_to_msecs(bfqq->wr_cur_max_time),
-+			bfqq->wr_coeff,
-+			bfqq->entity.weight, bfqq->entity.orig_weight);
-+
-+		BUG_ON(bfqq != bfqd->in_service_queue && entity->weight !=
-+		       entity->orig_weight * bfqq->wr_coeff);
-+		if (entity->prio_changed)
-+			bfq_log_bfqq(bfqd, bfqq, "WARN: pending prio change");
-+
-+		/*
-+		 * If the queue was activated in a burst, or too much
-+		 * time has elapsed from the beginning of this
-+		 * weight-raising period, then end weight raising.
-+		 */
-+		if (bfq_bfqq_in_large_burst(bfqq))
-+			bfq_bfqq_end_wr(bfqq);
-+		else if (time_is_before_jiffies(bfqq->last_wr_start_finish +
-+					   bfqq->wr_cur_max_time)) {
-+			if (bfqq->wr_cur_max_time != bfqd->bfq_wr_rt_max_time ||
-+			time_is_before_jiffies(bfqq->wr_start_at_switch_to_srt +
-+					bfq_wr_duration(bfqd)))
-+				bfq_bfqq_end_wr(bfqq);
-+			else {
-+				/* switch back to interactive wr */
-+				bfqq->wr_coeff = bfqd->bfq_wr_coeff;
-+				bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
-+				bfqq->last_wr_start_finish =
-+					bfqq->wr_start_at_switch_to_srt;
-+				BUG_ON(time_is_after_jiffies(
-+					       bfqq->last_wr_start_finish));
-+				bfqq->entity.prio_changed = 1;
-+				bfq_log_bfqq(bfqd, bfqq,
-+					"back to interactive wr");
-+			}
-+		}
-+	}
-+	/*
-+	 * To improve latency (for this or other queues), immediately
-+	 * update weight both if it must be raised and if it must be
-+	 * lowered. Since, entity may be on some active tree here, and
-+	 * might have a pending change of its ioprio class, invoke
-+	 * next function with the last parameter unset (see the
-+	 * comments on the function).
-+	 */
-+	if ((entity->weight > entity->orig_weight) != (bfqq->wr_coeff > 1))
-+		__bfq_entity_update_weight_prio(bfq_entity_service_tree(entity),
-+						entity, false);
-+}
-+
-+/*
-+ * Dispatch one request from bfqq, moving it to the request queue
-+ * dispatch list.
-+ */
-+static int bfq_dispatch_request(struct bfq_data *bfqd,
-+				struct bfq_queue *bfqq)
-+{
-+	int dispatched = 0;
-+	struct request *rq = bfqq->next_rq;
-+	unsigned long service_to_charge;
-+
-+	BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list));
-+	BUG_ON(!rq);
-+	service_to_charge = bfq_serv_to_charge(rq, bfqq);
-+
-+	BUG_ON(service_to_charge > bfq_bfqq_budget_left(bfqq));
-+
-+	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
-+
-+	bfq_bfqq_served(bfqq, service_to_charge);
-+
-+	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
-+
-+	bfq_dispatch_insert(bfqd->queue, rq);
-+
-+	/*
-+	 * If weight raising has to terminate for bfqq, then next
-+	 * function causes an immediate update of bfqq's weight,
-+	 * without waiting for next activation. As a consequence, on
-+	 * expiration, bfqq will be timestamped as if has never been
-+	 * weight-raised during this service slot, even if it has
-+	 * received part or even most of the service as a
-+	 * weight-raised queue. This inflates bfqq's timestamps, which
-+	 * is beneficial, as bfqq is then more willing to leave the
-+	 * device immediately to possible other weight-raised queues.
-+	 */
-+	bfq_update_wr_data(bfqd, bfqq);
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+			"dispatched %u sec req (%llu), budg left %d",
-+			blk_rq_sectors(rq),
-+			(unsigned long long) blk_rq_pos(rq),
-+			bfq_bfqq_budget_left(bfqq));
-+
-+	dispatched++;
-+
-+	if (!bfqd->in_service_bic) {
-+		atomic_long_inc(&RQ_BIC(rq)->icq.ioc->refcount);
-+		bfqd->in_service_bic = RQ_BIC(rq);
-+	}
-+
-+	if (bfqd->busy_queues > 1 && bfq_class_idle(bfqq))
-+		goto expire;
-+
-+	return dispatched;
-+
-+expire:
-+	bfq_bfqq_expire(bfqd, bfqq, false, BFQ_BFQQ_BUDGET_EXHAUSTED);
-+	return dispatched;
-+}
-+
-+static int __bfq_forced_dispatch_bfqq(struct bfq_queue *bfqq)
-+{
-+	int dispatched = 0;
-+
-+	while (bfqq->next_rq) {
-+		bfq_dispatch_insert(bfqq->bfqd->queue, bfqq->next_rq);
-+		dispatched++;
-+	}
-+
-+	BUG_ON(!list_empty(&bfqq->fifo));
-+	return dispatched;
-+}
-+
-+/*
-+ * Drain our current requests.
-+ * Used for barriers and when switching io schedulers on-the-fly.
-+ */
-+static int bfq_forced_dispatch(struct bfq_data *bfqd)
-+{
-+	struct bfq_queue *bfqq, *n;
-+	struct bfq_service_tree *st;
-+	int dispatched = 0;
-+
-+	bfqq = bfqd->in_service_queue;
-+	if (bfqq)
-+		__bfq_bfqq_expire(bfqd, bfqq);
-+
-+	/*
-+	 * Loop through classes, and be careful to leave the scheduler
-+	 * in a consistent state, as feedback mechanisms and vtime
-+	 * updates cannot be disabled during the process.
-+	 */
-+	list_for_each_entry_safe(bfqq, n, &bfqd->active_list, bfqq_list) {
-+		st = bfq_entity_service_tree(&bfqq->entity);
-+
-+		dispatched += __bfq_forced_dispatch_bfqq(bfqq);
-+
-+		bfqq->max_budget = bfq_max_budget(bfqd);
-+		bfq_forget_idle(st);
-+	}
-+
-+	BUG_ON(bfqd->busy_queues != 0);
-+
-+	return dispatched;
-+}
-+
-+static int bfq_dispatch_requests(struct request_queue *q, int force)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	struct bfq_queue *bfqq;
-+
-+	bfq_log(bfqd, "dispatch requests: %d busy queues", bfqd->busy_queues);
-+
-+	if (bfqd->busy_queues == 0)
-+		return 0;
-+
-+	if (unlikely(force))
-+		return bfq_forced_dispatch(bfqd);
-+
-+	/*
-+	 * Force device to serve one request at a time if
-+	 * strict_guarantees is true. Forcing this service scheme is
-+	 * currently the ONLY way to guarantee that the request
-+	 * service order enforced by the scheduler is respected by a
-+	 * queueing device. Otherwise the device is free even to make
-+	 * some unlucky request wait for as long as the device
-+	 * wishes.
-+	 *
-+	 * Of course, serving one request at at time may cause loss of
-+	 * throughput.
-+	 */
-+	if (bfqd->strict_guarantees && bfqd->rq_in_driver > 0)
-+		return 0;
-+
-+	bfqq = bfq_select_queue(bfqd);
-+	if (!bfqq)
-+		return 0;
-+
-+	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
-+
-+	BUG_ON(bfq_bfqq_wait_request(bfqq));
-+
-+	if (!bfq_dispatch_request(bfqd, bfqq))
-+		return 0;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "dispatched %s request",
-+			bfq_bfqq_sync(bfqq) ? "sync" : "async");
-+
-+	BUG_ON(bfqq->next_rq == NULL &&
-+	       bfqq->entity.budget < bfqq->entity.service);
-+	return 1;
-+}
-+
-+/*
-+ * Task holds one reference to the queue, dropped when task exits.  Each rq
-+ * in-flight on this queue also holds a reference, dropped when rq is freed.
-+ *
-+ * Queue lock must be held here. Recall not to use bfqq after calling
-+ * this function on it.
-+ */
-+static void bfq_put_queue(struct bfq_queue *bfqq)
-+{
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	struct bfq_group *bfqg = bfqq_group(bfqq);
-+#endif
-+
-+	BUG_ON(bfqq->ref <= 0);
-+
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "put_queue: %p %d", bfqq, bfqq->ref);
-+	bfqq->ref--;
-+	if (bfqq->ref)
-+		return;
-+
-+	BUG_ON(rb_first(&bfqq->sort_list));
-+	BUG_ON(bfqq->allocated[READ] + bfqq->allocated[WRITE] != 0);
-+	BUG_ON(bfqq->entity.tree);
-+	BUG_ON(bfq_bfqq_busy(bfqq));
-+
-+	if (bfq_bfqq_sync(bfqq))
-+		/*
-+		 * The fact that this queue is being destroyed does not
-+		 * invalidate the fact that this queue may have been
-+		 * activated during the current burst. As a consequence,
-+		 * although the queue does not exist anymore, and hence
-+		 * needs to be removed from the burst list if there,
-+		 * the burst size has not to be decremented.
-+		 */
-+		hlist_del_init(&bfqq->burst_list_node);
-+
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "put_queue: %p freed", bfqq);
-+
-+	kmem_cache_free(bfq_pool, bfqq);
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	bfqg_put(bfqg);
-+#endif
-+}
-+
-+static void bfq_put_cooperator(struct bfq_queue *bfqq)
-+{
-+	struct bfq_queue *__bfqq, *next;
-+
-+	/*
-+	 * If this queue was scheduled to merge with another queue, be
-+	 * sure to drop the reference taken on that queue (and others in
-+	 * the merge chain). See bfq_setup_merge and bfq_merge_bfqqs.
-+	 */
-+	__bfqq = bfqq->new_bfqq;
-+	while (__bfqq) {
-+		if (__bfqq == bfqq)
-+			break;
-+		next = __bfqq->new_bfqq;
-+		bfq_put_queue(__bfqq);
-+		__bfqq = next;
-+	}
-+}
-+
-+static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	if (bfqq == bfqd->in_service_queue) {
-+		__bfq_bfqq_expire(bfqd, bfqq);
-+		bfq_schedule_dispatch(bfqd);
-+	}
-+
-+	bfq_log_bfqq(bfqd, bfqq, "exit_bfqq: %p, %d", bfqq, bfqq->ref);
-+
-+	bfq_put_cooperator(bfqq);
-+
-+	bfq_put_queue(bfqq); /* release process reference */
-+}
-+
-+static void bfq_init_icq(struct io_cq *icq)
-+{
-+	icq_to_bic(icq)->ttime.last_end_request = ktime_get_ns() - (1ULL<<32);
-+}
-+
-+static void bfq_exit_icq(struct io_cq *icq)
-+{
-+	struct bfq_io_cq *bic = icq_to_bic(icq);
-+	struct bfq_data *bfqd = bic_to_bfqd(bic);
-+
-+	if (bic_to_bfqq(bic, false)) {
-+		bfq_exit_bfqq(bfqd, bic_to_bfqq(bic, false));
-+		bic_set_bfqq(bic, NULL, false);
-+	}
-+
-+	if (bic_to_bfqq(bic, true)) {
-+		/*
-+		 * If the bic is using a shared queue, put the reference
-+		 * taken on the io_context when the bic started using a
-+		 * shared bfq_queue.
-+		 */
-+		if (bfq_bfqq_coop(bic_to_bfqq(bic, true)))
-+			put_io_context(icq->ioc);
-+		bfq_exit_bfqq(bfqd, bic_to_bfqq(bic, true));
-+		bic_set_bfqq(bic, NULL, true);
-+	}
-+}
-+
-+/*
-+ * Update the entity prio values; note that the new values will not
-+ * be used until the next (re)activation.
-+ */
-+static void bfq_set_next_ioprio_data(struct bfq_queue *bfqq,
-+				     struct bfq_io_cq *bic)
-+{
-+	struct task_struct *tsk = current;
-+	int ioprio_class;
-+
-+	ioprio_class = IOPRIO_PRIO_CLASS(bic->ioprio);
-+	switch (ioprio_class) {
-+	default:
-+		dev_err(bfqq->bfqd->queue->backing_dev_info->dev,
-+			"bfq: bad prio class %d\n", ioprio_class);
-+	case IOPRIO_CLASS_NONE:
-+		/*
-+		 * No prio set, inherit CPU scheduling settings.
-+		 */
-+		bfqq->new_ioprio = task_nice_ioprio(tsk);
-+		bfqq->new_ioprio_class = task_nice_ioclass(tsk);
-+		break;
-+	case IOPRIO_CLASS_RT:
-+		bfqq->new_ioprio = IOPRIO_PRIO_DATA(bic->ioprio);
-+		bfqq->new_ioprio_class = IOPRIO_CLASS_RT;
-+		break;
-+	case IOPRIO_CLASS_BE:
-+		bfqq->new_ioprio = IOPRIO_PRIO_DATA(bic->ioprio);
-+		bfqq->new_ioprio_class = IOPRIO_CLASS_BE;
-+		break;
-+	case IOPRIO_CLASS_IDLE:
-+		bfqq->new_ioprio_class = IOPRIO_CLASS_IDLE;
-+		bfqq->new_ioprio = 7;
-+		break;
-+	}
-+
-+	if (bfqq->new_ioprio >= IOPRIO_BE_NR) {
-+		pr_crit("bfq_set_next_ioprio_data: new_ioprio %d\n",
-+			bfqq->new_ioprio);
-+		BUG();
-+	}
-+
-+	bfqq->entity.new_weight = bfq_ioprio_to_weight(bfqq->new_ioprio);
-+	bfqq->entity.prio_changed = 1;
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		     "set_next_ioprio_data: bic_class %d prio %d class %d",
-+		     ioprio_class, bfqq->new_ioprio, bfqq->new_ioprio_class);
-+}
-+
-+static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio)
-+{
-+	struct bfq_data *bfqd = bic_to_bfqd(bic);
-+	struct bfq_queue *bfqq;
-+	unsigned long uninitialized_var(flags);
-+	int ioprio = bic->icq.ioc->ioprio;
-+
-+	/*
-+	 * This condition may trigger on a newly created bic, be sure to
-+	 * drop the lock before returning.
-+	 */
-+	if (unlikely(!bfqd) || likely(bic->ioprio == ioprio))
-+		return;
-+
-+	bic->ioprio = ioprio;
-+
-+	bfqq = bic_to_bfqq(bic, false);
-+	if (bfqq) {
-+		/* release process reference on this queue */
-+		bfq_put_queue(bfqq);
-+		bfqq = bfq_get_queue(bfqd, bio, BLK_RW_ASYNC, bic);
-+		bic_set_bfqq(bic, bfqq, false);
-+		bfq_log_bfqq(bfqd, bfqq,
-+			     "check_ioprio_change: bfqq %p %d",
-+			     bfqq, bfqq->ref);
-+	}
-+
-+	bfqq = bic_to_bfqq(bic, true);
-+	if (bfqq)
-+		bfq_set_next_ioprio_data(bfqq, bic);
-+}
-+
-+static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+			  struct bfq_io_cq *bic, pid_t pid, int is_sync)
-+{
-+	RB_CLEAR_NODE(&bfqq->entity.rb_node);
-+	INIT_LIST_HEAD(&bfqq->fifo);
-+	INIT_HLIST_NODE(&bfqq->burst_list_node);
-+	BUG_ON(!hlist_unhashed(&bfqq->burst_list_node));
-+
-+	bfqq->ref = 0;
-+	bfqq->bfqd = bfqd;
-+
-+	if (bic)
-+		bfq_set_next_ioprio_data(bfqq, bic);
-+
-+	if (is_sync) {
-+		/*
-+		 * No need to mark as has_short_ttime if in
-+		 * idle_class, because no device idling is performed
-+		 * for queues in idle class
-+		 */
-+		if (!bfq_class_idle(bfqq))
-+			/* tentatively mark as has_short_ttime */
-+			bfq_mark_bfqq_has_short_ttime(bfqq);
-+		bfq_mark_bfqq_sync(bfqq);
-+		bfq_mark_bfqq_just_created(bfqq);
-+	} else
-+		bfq_clear_bfqq_sync(bfqq);
-+	bfq_mark_bfqq_IO_bound(bfqq);
-+
-+	/* Tentative initial value to trade off between thr and lat */
-+	bfqq->max_budget = (2 * bfq_max_budget(bfqd)) / 3;
-+	bfqq->pid = pid;
-+
-+	bfqq->wr_coeff = 1;
-+	bfqq->last_wr_start_finish = jiffies;
-+	bfqq->wr_start_at_switch_to_srt = bfq_smallest_from_now();
-+	bfqq->budget_timeout = bfq_smallest_from_now();
-+	bfqq->split_time = bfq_smallest_from_now();
-+
-+	/*
-+	 * Set to the value for which bfqq will not be deemed as
-+	 * soft rt when it becomes backlogged.
-+	 */
-+	bfqq->soft_rt_next_start = bfq_greatest_from_now();
-+
-+	/* first request is almost certainly seeky */
-+	bfqq->seek_history = 1;
-+}
-+
-+static struct bfq_queue **bfq_async_queue_prio(struct bfq_data *bfqd,
-+					       struct bfq_group *bfqg,
-+					       int ioprio_class, int ioprio)
-+{
-+	switch (ioprio_class) {
-+	case IOPRIO_CLASS_RT:
-+		return &bfqg->async_bfqq[0][ioprio];
-+	case IOPRIO_CLASS_NONE:
-+		ioprio = IOPRIO_NORM;
-+		/* fall through */
-+	case IOPRIO_CLASS_BE:
-+		return &bfqg->async_bfqq[1][ioprio];
-+	case IOPRIO_CLASS_IDLE:
-+		return &bfqg->async_idle_bfqq;
-+	default:
-+		BUG();
-+	}
-+}
-+
-+static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd,
-+				       struct bio *bio, bool is_sync,
-+				       struct bfq_io_cq *bic)
-+{
-+	const int ioprio = IOPRIO_PRIO_DATA(bic->ioprio);
-+	const int ioprio_class = IOPRIO_PRIO_CLASS(bic->ioprio);
-+	struct bfq_queue **async_bfqq = NULL;
-+	struct bfq_queue *bfqq;
-+	struct bfq_group *bfqg;
-+
-+	rcu_read_lock();
-+
-+	bfqg = bfq_find_set_group(bfqd, bio_blkcg(bio));
-+	if (!bfqg) {
-+		bfqq = &bfqd->oom_bfqq;
-+		goto out;
-+	}
-+
-+	if (!is_sync) {
-+		async_bfqq = bfq_async_queue_prio(bfqd, bfqg, ioprio_class,
-+						  ioprio);
-+		bfqq = *async_bfqq;
-+		if (bfqq)
-+			goto out;
-+	}
-+
-+	bfqq = kmem_cache_alloc_node(bfq_pool,
-+				     GFP_NOWAIT | __GFP_ZERO | __GFP_NOWARN,
-+				     bfqd->queue->node);
-+
-+	if (bfqq) {
-+		bfq_init_bfqq(bfqd, bfqq, bic, current->pid,
-+			      is_sync);
-+		bfq_init_entity(&bfqq->entity, bfqg);
-+		bfq_log_bfqq(bfqd, bfqq, "allocated");
-+	} else {
-+		bfqq = &bfqd->oom_bfqq;
-+		bfq_log_bfqq(bfqd, bfqq, "using oom bfqq");
-+		goto out;
-+	}
-+
-+	/*
-+	 * Pin the queue now that it's allocated, scheduler exit will
-+	 * prune it.
-+	 */
-+	if (async_bfqq) {
-+		bfqq->ref++; /*
-+			      * Extra group reference, w.r.t. sync
-+			      * queue. This extra reference is removed
-+			      * only if bfqq->bfqg disappears, to
-+			      * guarantee that this queue is not freed
-+			      * until its group goes away.
-+			      */
-+		bfq_log_bfqq(bfqd, bfqq, "get_queue, bfqq not in async: %p, %d",
-+			     bfqq, bfqq->ref);
-+		*async_bfqq = bfqq;
-+	}
-+
-+out:
-+	bfqq->ref++; /* get a process reference to this queue */
-+	bfq_log_bfqq(bfqd, bfqq, "get_queue, at end: %p, %d", bfqq, bfqq->ref);
-+	rcu_read_unlock();
-+	return bfqq;
-+}
-+
-+static void bfq_update_io_thinktime(struct bfq_data *bfqd,
-+				    struct bfq_io_cq *bic)
-+{
-+	struct bfq_ttime *ttime = &bic->ttime;
-+	u64 elapsed = ktime_get_ns() - bic->ttime.last_end_request;
-+
-+	elapsed = min_t(u64, elapsed, 2 * bfqd->bfq_slice_idle);
-+
-+	ttime->ttime_samples = (7*bic->ttime.ttime_samples + 256) / 8;
-+	ttime->ttime_total = div_u64(7*ttime->ttime_total + 256*elapsed,  8);
-+	ttime->ttime_mean = div64_ul(ttime->ttime_total + 128,
-+				     ttime->ttime_samples);
-+}
-+
-+static void
-+bfq_update_io_seektime(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+		       struct request *rq)
-+{
-+	bfqq->seek_history <<= 1;
-+	bfqq->seek_history |=
-+		get_sdist(bfqq->last_request_pos, rq) > BFQQ_SEEK_THR &&
-+		(!blk_queue_nonrot(bfqd->queue) ||
-+		 blk_rq_sectors(rq) < BFQQ_SECT_THR_NONROT);
-+}
-+
-+static void bfq_update_has_short_ttime(struct bfq_data *bfqd,
-+				       struct bfq_queue *bfqq,
-+				       struct bfq_io_cq *bic)
-+{
-+	bool has_short_ttime = true;
-+
-+	/*
-+	 * No need to update has_short_ttime if bfqq is async or in
-+	 * idle io prio class, or if bfq_slice_idle is zero, because
-+	 * no device idling is performed for bfqq in this case.
-+	 */
-+	if (!bfq_bfqq_sync(bfqq) || bfq_class_idle(bfqq) ||
-+	    bfqd->bfq_slice_idle == 0)
-+		return;
-+
-+	/* Idle window just restored, statistics are meaningless. */
-+	if (time_is_after_eq_jiffies(bfqq->split_time +
-+				     bfqd->bfq_wr_min_idle_time))
-+		return;
-+
-+	/* Think time is infinite if no process is linked to
-+	 * bfqq. Otherwise check average think time to
-+	 * decide whether to mark as has_short_ttime
-+	 */
-+	if (atomic_read(&bic->icq.ioc->active_ref) == 0 ||
-+	    (bfq_sample_valid(bic->ttime.ttime_samples) &&
-+	     bic->ttime.ttime_mean > bfqd->bfq_slice_idle))
-+		has_short_ttime = false;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "update_has_short_ttime: has_short_ttime %d",
-+		has_short_ttime);
-+
-+	if (has_short_ttime)
-+		bfq_mark_bfqq_has_short_ttime(bfqq);
-+	else
-+		bfq_clear_bfqq_has_short_ttime(bfqq);
-+}
-+
-+/*
-+ * Called when a new fs request (rq) is added to bfqq.  Check if there's
-+ * something we should do about it.
-+ */
-+static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+			    struct request *rq)
-+{
-+	struct bfq_io_cq *bic = RQ_BIC(rq);
-+
-+	if (rq->cmd_flags & REQ_META)
-+		bfqq->meta_pending++;
-+
-+	bfq_update_io_thinktime(bfqd, bic);
-+	bfq_update_has_short_ttime(bfqd, bfqq, bic);
-+	bfq_update_io_seektime(bfqd, bfqq, rq);
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+		     "rq_enqueued: has_short_ttime=%d (seeky %d)",
-+		     bfq_bfqq_has_short_ttime(bfqq), BFQQ_SEEKY(bfqq));
-+
-+	bfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
-+
-+	if (bfqq == bfqd->in_service_queue && bfq_bfqq_wait_request(bfqq)) {
-+		bool small_req = bfqq->queued[rq_is_sync(rq)] == 1 &&
-+				 blk_rq_sectors(rq) < 32;
-+		bool budget_timeout = bfq_bfqq_budget_timeout(bfqq);
-+
-+		/*
-+		 * There is just this request queued: if the request
-+		 * is small and the queue is not to be expired, then
-+		 * just exit.
-+		 *
-+		 * In this way, if the device is being idled to wait
-+		 * for a new request from the in-service queue, we
-+		 * avoid unplugging the device and committing the
-+		 * device to serve just a small request. On the
-+		 * contrary, we wait for the block layer to decide
-+		 * when to unplug the device: hopefully, new requests
-+		 * will be merged to this one quickly, then the device
-+		 * will be unplugged and larger requests will be
-+		 * dispatched.
-+		 */
-+		if (small_req && !budget_timeout)
-+			return;
-+
-+		/*
-+		 * A large enough request arrived, or the queue is to
-+		 * be expired: in both cases disk idling is to be
-+		 * stopped, so clear wait_request flag and reset
-+		 * timer.
-+		 */
-+		bfq_clear_bfqq_wait_request(bfqq);
-+		hrtimer_try_to_cancel(&bfqd->idle_slice_timer);
-+		bfqg_stats_update_idle_time(bfqq_group(bfqq));
-+
-+		/*
-+		 * The queue is not empty, because a new request just
-+		 * arrived. Hence we can safely expire the queue, in
-+		 * case of budget timeout, without risking that the
-+		 * timestamps of the queue are not updated correctly.
-+		 * See [1] for more details.
-+		 */
-+		if (budget_timeout)
-+			bfq_bfqq_expire(bfqd, bfqq, false,
-+					BFQ_BFQQ_BUDGET_TIMEOUT);
-+
-+		/*
-+		 * Let the request rip immediately, or let a new queue be
-+		 * selected if bfqq has just been expired.
-+		 */
-+		__blk_run_queue(bfqd->queue);
-+	}
-+}
-+
-+static void bfq_insert_request(struct request_queue *q, struct request *rq)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq), *new_bfqq;
-+
-+	assert_spin_locked(bfqd->queue->queue_lock);
-+
-+	/*
-+	 * An unplug may trigger a requeue of a request from the device
-+	 * driver: make sure we are in process context while trying to
-+	 * merge two bfq_queues.
-+	 */
-+	if (!in_interrupt()) {
-+		new_bfqq = bfq_setup_cooperator(bfqd, bfqq, rq, true);
-+		if (new_bfqq) {
-+			if (bic_to_bfqq(RQ_BIC(rq), 1) != bfqq)
-+				new_bfqq = bic_to_bfqq(RQ_BIC(rq), 1);
-+			/*
-+			 * Release the request's reference to the old bfqq
-+			 * and make sure one is taken to the shared queue.
-+			 */
-+			new_bfqq->allocated[rq_data_dir(rq)]++;
-+			bfqq->allocated[rq_data_dir(rq)]--;
-+			new_bfqq->ref++;
-+			bfq_clear_bfqq_just_created(bfqq);
-+			if (bic_to_bfqq(RQ_BIC(rq), 1) == bfqq)
-+				bfq_merge_bfqqs(bfqd, RQ_BIC(rq),
-+						bfqq, new_bfqq);
-+			/*
-+			 * rq is about to be enqueued into new_bfqq,
-+			 * release rq reference on bfqq
-+			 */
-+			bfq_put_queue(bfqq);
-+			rq->elv.priv[1] = new_bfqq;
-+			bfqq = new_bfqq;
-+		}
-+	}
-+
-+	bfq_add_request(rq);
-+
-+	rq->fifo_time = ktime_get_ns() + bfqd->bfq_fifo_expire[rq_is_sync(rq)];
-+	list_add_tail(&rq->queuelist, &bfqq->fifo);
-+
-+	bfq_rq_enqueued(bfqd, bfqq, rq);
-+}
-+
-+static void bfq_update_hw_tag(struct bfq_data *bfqd)
-+{
-+	bfqd->max_rq_in_driver = max_t(int, bfqd->max_rq_in_driver,
-+				       bfqd->rq_in_driver);
-+
-+	if (bfqd->hw_tag == 1)
-+		return;
-+
-+	/*
-+	 * This sample is valid if the number of outstanding requests
-+	 * is large enough to allow a queueing behavior.  Note that the
-+	 * sum is not exact, as it's not taking into account deactivated
-+	 * requests.
-+	 */
-+	if (bfqd->rq_in_driver + bfqd->queued < BFQ_HW_QUEUE_THRESHOLD)
-+		return;
-+
-+	if (bfqd->hw_tag_samples++ < BFQ_HW_QUEUE_SAMPLES)
-+		return;
-+
-+	bfqd->hw_tag = bfqd->max_rq_in_driver > BFQ_HW_QUEUE_THRESHOLD;
-+	bfqd->max_rq_in_driver = 0;
-+	bfqd->hw_tag_samples = 0;
-+}
-+
-+static void bfq_completed_request(struct request_queue *q, struct request *rq)
-+{
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq);
-+	struct bfq_data *bfqd = bfqq->bfqd;
-+	u64 now_ns;
-+	u32 delta_us;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "completed one req with %u sects left",
-+		     blk_rq_sectors(rq));
-+
-+	assert_spin_locked(bfqd->queue->queue_lock);
-+	bfq_update_hw_tag(bfqd);
-+
-+	BUG_ON(!bfqd->rq_in_driver);
-+	BUG_ON(!bfqq->dispatched);
-+	bfqd->rq_in_driver--;
-+	bfqq->dispatched--;
-+	bfqg_stats_update_completion(bfqq_group(bfqq),
-+				     rq_start_time_ns(rq),
-+				     rq_io_start_time_ns(rq),
-+				     rq->cmd_flags);
-+
-+	if (!bfqq->dispatched && !bfq_bfqq_busy(bfqq)) {
-+		BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list));
-+		/*
-+		 * Set budget_timeout (which we overload to store the
-+		 * time at which the queue remains with no backlog and
-+		 * no outstanding request; used by the weight-raising
-+		 * mechanism).
-+		 */
-+		bfqq->budget_timeout = jiffies;
-+
-+		bfq_weights_tree_remove(bfqd, &bfqq->entity,
-+					&bfqd->queue_weights_tree);
-+	}
-+
-+	now_ns = ktime_get_ns();
-+
-+	RQ_BIC(rq)->ttime.last_end_request = now_ns;
-+
-+	/*
-+	 * Using us instead of ns, to get a reasonable precision in
-+	 * computing rate in next check.
-+	 */
-+	delta_us = div_u64(now_ns - bfqd->last_completion, NSEC_PER_USEC);
-+
-+	bfq_log(bfqd, "rq_completed: delta %uus/%luus max_size %u rate %llu/%llu",
-+		delta_us, BFQ_MIN_TT/NSEC_PER_USEC, bfqd->last_rq_max_size,
-+		(USEC_PER_SEC*
-+		(u64)((bfqd->last_rq_max_size<<BFQ_RATE_SHIFT)/delta_us))
-+			>>BFQ_RATE_SHIFT,
-+		(USEC_PER_SEC*(u64)(1UL<<(BFQ_RATE_SHIFT-10)))>>BFQ_RATE_SHIFT);
-+
-+	/*
-+	 * If the request took rather long to complete, and, according
-+	 * to the maximum request size recorded, this completion latency
-+	 * implies that the request was certainly served at a very low
-+	 * rate (less than 1M sectors/sec), then the whole observation
-+	 * interval that lasts up to this time instant cannot be a
-+	 * valid time interval for computing a new peak rate.  Invoke
-+	 * bfq_update_rate_reset to have the following three steps
-+	 * taken:
-+	 * - close the observation interval at the last (previous)
-+	 *   request dispatch or completion
-+	 * - compute rate, if possible, for that observation interval
-+	 * - reset to zero samples, which will trigger a proper
-+	 *   re-initialization of the observation interval on next
-+	 *   dispatch
-+	 */
-+	if (delta_us > BFQ_MIN_TT/NSEC_PER_USEC &&
-+	   (bfqd->last_rq_max_size<<BFQ_RATE_SHIFT)/delta_us <
-+			1UL<<(BFQ_RATE_SHIFT - 10))
-+		bfq_update_rate_reset(bfqd, NULL);
-+	bfqd->last_completion = now_ns;
-+
-+	/*
-+	 * If we are waiting to discover whether the request pattern
-+	 * of the task associated with the queue is actually
-+	 * isochronous, and both requisites for this condition to hold
-+	 * are now satisfied, then compute soft_rt_next_start (see the
-+	 * comments on the function bfq_bfqq_softrt_next_start()). We
-+	 * schedule this delayed check when bfqq expires, if it still
-+	 * has in-flight requests.
-+	 */
-+	if (bfq_bfqq_softrt_update(bfqq) && bfqq->dispatched == 0 &&
-+	    RB_EMPTY_ROOT(&bfqq->sort_list))
-+		bfqq->soft_rt_next_start =
-+			bfq_bfqq_softrt_next_start(bfqd, bfqq);
-+
-+	/*
-+	 * If this is the in-service queue, check if it needs to be expired,
-+	 * or if we want to idle in case it has no pending requests.
-+	 */
-+	if (bfqd->in_service_queue == bfqq) {
-+		if (bfqq->dispatched == 0 && bfq_bfqq_must_idle(bfqq)) {
-+			bfq_arm_slice_timer(bfqd);
-+			goto out;
-+		} else if (bfq_may_expire_for_budg_timeout(bfqq))
-+			bfq_bfqq_expire(bfqd, bfqq, false,
-+					BFQ_BFQQ_BUDGET_TIMEOUT);
-+		else if (RB_EMPTY_ROOT(&bfqq->sort_list) &&
-+			 (bfqq->dispatched == 0 ||
-+			  !bfq_bfqq_may_idle(bfqq)))
-+			bfq_bfqq_expire(bfqd, bfqq, false,
-+					BFQ_BFQQ_NO_MORE_REQUESTS);
-+	}
-+
-+	if (!bfqd->rq_in_driver)
-+		bfq_schedule_dispatch(bfqd);
-+
-+out:
-+	return;
-+}
-+
-+static int __bfq_may_queue(struct bfq_queue *bfqq)
-+{
-+	if (bfq_bfqq_wait_request(bfqq) && bfq_bfqq_must_alloc(bfqq)) {
-+		bfq_clear_bfqq_must_alloc(bfqq);
-+		return ELV_MQUEUE_MUST;
-+	}
-+
-+	return ELV_MQUEUE_MAY;
-+}
-+
-+static int bfq_may_queue(struct request_queue *q, unsigned int op)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	struct task_struct *tsk = current;
-+	struct bfq_io_cq *bic;
-+	struct bfq_queue *bfqq;
-+
-+	/*
-+	 * Don't force setup of a queue from here, as a call to may_queue
-+	 * does not necessarily imply that a request actually will be
-+	 * queued. So just lookup a possibly existing queue, or return
-+	 * 'may queue' if that fails.
-+	 */
-+	bic = bfq_bic_lookup(bfqd, tsk->io_context);
-+	if (!bic)
-+		return ELV_MQUEUE_MAY;
-+
-+	bfqq = bic_to_bfqq(bic, op_is_sync(op));
-+	if (bfqq)
-+		return __bfq_may_queue(bfqq);
-+
-+	return ELV_MQUEUE_MAY;
-+}
-+
-+/*
-+ * Queue lock held here.
-+ */
-+static void bfq_put_request(struct request *rq)
-+{
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq);
-+
-+	if (bfqq) {
-+		const int rw = rq_data_dir(rq);
-+
-+		BUG_ON(!bfqq->allocated[rw]);
-+		bfqq->allocated[rw]--;
-+
-+		rq->elv.priv[0] = NULL;
-+		rq->elv.priv[1] = NULL;
-+
-+		bfq_log_bfqq(bfqq->bfqd, bfqq, "put_request %p, %d",
-+			     bfqq, bfqq->ref);
-+		bfq_put_queue(bfqq);
-+	}
-+}
-+
-+/*
-+ * Returns NULL if a new bfqq should be allocated, or the old bfqq if this
-+ * was the last process referring to that bfqq.
-+ */
-+static struct bfq_queue *
-+bfq_split_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq)
-+{
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "splitting queue");
-+
-+	put_io_context(bic->icq.ioc);
-+
-+	if (bfqq_process_refs(bfqq) == 1) {
-+		bfqq->pid = current->pid;
-+		bfq_clear_bfqq_coop(bfqq);
-+		bfq_clear_bfqq_split_coop(bfqq);
-+		return bfqq;
-+	}
-+
-+	bic_set_bfqq(bic, NULL, 1);
-+
-+	bfq_put_cooperator(bfqq);
-+
-+	bfq_put_queue(bfqq);
-+	return NULL;
-+}
-+
-+/*
-+ * Allocate bfq data structures associated with this request.
-+ */
-+static int bfq_set_request(struct request_queue *q, struct request *rq,
-+			   struct bio *bio, gfp_t gfp_mask)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	struct bfq_io_cq *bic = icq_to_bic(rq->elv.icq);
-+	const int rw = rq_data_dir(rq);
-+	const int is_sync = rq_is_sync(rq);
-+	struct bfq_queue *bfqq;
-+	unsigned long flags;
-+	bool bfqq_already_existing = false, split = false;
-+
-+	spin_lock_irqsave(q->queue_lock, flags);
-+
-+	if (!bic)
-+		goto queue_fail;
-+
-+	bfq_check_ioprio_change(bic, bio);
-+
-+	bfq_bic_update_cgroup(bic, bio);
-+
-+new_queue:
-+	bfqq = bic_to_bfqq(bic, is_sync);
-+	if (!bfqq || bfqq == &bfqd->oom_bfqq) {
-+		if (bfqq)
-+			bfq_put_queue(bfqq);
-+		bfqq = bfq_get_queue(bfqd, bio, is_sync, bic);
-+		BUG_ON(!hlist_unhashed(&bfqq->burst_list_node));
-+
-+		bic_set_bfqq(bic, bfqq, is_sync);
-+		if (split && is_sync) {
-+			bfq_log_bfqq(bfqd, bfqq,
-+				     "set_request: was_in_list %d "
-+				     "was_in_large_burst %d "
-+				     "large burst in progress %d",
-+				     bic->was_in_burst_list,
-+				     bic->saved_in_large_burst,
-+				     bfqd->large_burst);
-+
-+			if ((bic->was_in_burst_list && bfqd->large_burst) ||
-+			    bic->saved_in_large_burst) {
-+				bfq_log_bfqq(bfqd, bfqq,
-+					     "set_request: marking in "
-+					     "large burst");
-+				bfq_mark_bfqq_in_large_burst(bfqq);
-+			} else {
-+				bfq_log_bfqq(bfqd, bfqq,
-+					     "set_request: clearing in "
-+					     "large burst");
-+				bfq_clear_bfqq_in_large_burst(bfqq);
-+				if (bic->was_in_burst_list)
-+					hlist_add_head(&bfqq->burst_list_node,
-+						       &bfqd->burst_list);
-+			}
-+			bfqq->split_time = jiffies;
-+		}
-+	} else {
-+		/* If the queue was seeky for too long, break it apart. */
-+		if (bfq_bfqq_coop(bfqq) && bfq_bfqq_split_coop(bfqq)) {
-+			bfq_log_bfqq(bfqd, bfqq, "breaking apart bfqq");
-+
-+			/* Update bic before losing reference to bfqq */
-+			if (bfq_bfqq_in_large_burst(bfqq))
-+				bic->saved_in_large_burst = true;
-+
-+			bfqq = bfq_split_bfqq(bic, bfqq);
-+			split = true;
-+			if (!bfqq)
-+				goto new_queue;
-+			else
-+				bfqq_already_existing = true;
-+		}
-+	}
-+
-+	bfqq->allocated[rw]++;
-+	bfqq->ref++;
-+	bfq_log_bfqq(bfqd, bfqq, "set_request: bfqq %p, %d", bfqq, bfqq->ref);
-+
-+	rq->elv.priv[0] = bic;
-+	rq->elv.priv[1] = bfqq;
-+
-+	/*
-+	 * If a bfq_queue has only one process reference, it is owned
-+	 * by only one bfq_io_cq: we can set the bic field of the
-+	 * bfq_queue to the address of that structure. Also, if the
-+	 * queue has just been split, mark a flag so that the
-+	 * information is available to the other scheduler hooks.
-+	 */
-+	if (likely(bfqq != &bfqd->oom_bfqq) && bfqq_process_refs(bfqq) == 1) {
-+		bfqq->bic = bic;
-+		if (split) {
-+			/*
-+			 * If the queue has just been split from a shared
-+			 * queue, restore the idle window and the possible
-+			 * weight raising period.
-+			 */
-+			bfq_bfqq_resume_state(bfqq, bfqd, bic,
-+					      bfqq_already_existing);
-+		}
-+	}
-+
-+	if (unlikely(bfq_bfqq_just_created(bfqq)))
-+		bfq_handle_burst(bfqd, bfqq);
-+
-+	spin_unlock_irqrestore(q->queue_lock, flags);
-+
-+	return 0;
-+
-+queue_fail:
-+	bfq_schedule_dispatch(bfqd);
-+	spin_unlock_irqrestore(q->queue_lock, flags);
-+
-+	return 1;
-+}
-+
-+static void bfq_kick_queue(struct work_struct *work)
-+{
-+	struct bfq_data *bfqd =
-+		container_of(work, struct bfq_data, unplug_work);
-+	struct request_queue *q = bfqd->queue;
-+
-+	spin_lock_irq(q->queue_lock);
-+	__blk_run_queue(q);
-+	spin_unlock_irq(q->queue_lock);
-+}
-+
-+/*
-+ * Handler of the expiration of the timer running if the in-service queue
-+ * is idling inside its time slice.
-+ */
-+static enum hrtimer_restart bfq_idle_slice_timer(struct hrtimer *timer)
-+{
-+	struct bfq_data *bfqd = container_of(timer, struct bfq_data,
-+					     idle_slice_timer);
-+	struct bfq_queue *bfqq;
-+	unsigned long flags;
-+	enum bfqq_expiration reason;
-+
-+	spin_lock_irqsave(bfqd->queue->queue_lock, flags);
-+
-+	bfqq = bfqd->in_service_queue;
-+	/*
-+	 * Theoretical race here: the in-service queue can be NULL or
-+	 * different from the queue that was idling if the timer handler
-+	 * spins on the queue_lock and a new request arrives for the
-+	 * current queue and there is a full dispatch cycle that changes
-+	 * the in-service queue.  This can hardly happen, but in the worst
-+	 * case we just expire a queue too early.
-+	 */
-+	if (bfqq) {
-+		bfq_log_bfqq(bfqd, bfqq, "slice_timer expired");
-+		bfq_clear_bfqq_wait_request(bfqq);
-+
-+		if (bfq_bfqq_budget_timeout(bfqq))
-+			/*
-+			 * Also here the queue can be safely expired
-+			 * for budget timeout without wasting
-+			 * guarantees
-+			 */
-+			reason = BFQ_BFQQ_BUDGET_TIMEOUT;
-+		else if (bfqq->queued[0] == 0 && bfqq->queued[1] == 0)
-+			/*
-+			 * The queue may not be empty upon timer expiration,
-+			 * because we may not disable the timer when the
-+			 * first request of the in-service queue arrives
-+			 * during disk idling.
-+			 */
-+			reason = BFQ_BFQQ_TOO_IDLE;
-+		else
-+			goto schedule_dispatch;
-+
-+		bfq_bfqq_expire(bfqd, bfqq, true, reason);
-+	}
-+
-+schedule_dispatch:
-+	bfq_schedule_dispatch(bfqd);
-+
-+	spin_unlock_irqrestore(bfqd->queue->queue_lock, flags);
-+	return HRTIMER_NORESTART;
-+}
-+
-+static void bfq_shutdown_timer_wq(struct bfq_data *bfqd)
-+{
-+	hrtimer_cancel(&bfqd->idle_slice_timer);
-+	cancel_work_sync(&bfqd->unplug_work);
-+}
-+
-+static void __bfq_put_async_bfqq(struct bfq_data *bfqd,
-+				 struct bfq_queue **bfqq_ptr)
-+{
-+	struct bfq_group *root_group = bfqd->root_group;
-+	struct bfq_queue *bfqq = *bfqq_ptr;
-+
-+	bfq_log(bfqd, "put_async_bfqq: %p", bfqq);
-+	if (bfqq) {
-+		bfq_bfqq_move(bfqd, bfqq, root_group);
-+		bfq_log_bfqq(bfqd, bfqq, "put_async_bfqq: putting %p, %d",
-+			     bfqq, bfqq->ref);
-+		bfq_put_queue(bfqq);
-+		*bfqq_ptr = NULL;
-+	}
-+}
-+
-+/*
-+ * Release all the bfqg references to its async queues.  If we are
-+ * deallocating the group these queues may still contain requests, so
-+ * we reparent them to the root cgroup (i.e., the only one that will
-+ * exist for sure until all the requests on a device are gone).
-+ */
-+static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg)
-+{
-+	int i, j;
-+
-+	for (i = 0; i < 2; i++)
-+		for (j = 0; j < IOPRIO_BE_NR; j++)
-+			__bfq_put_async_bfqq(bfqd, &bfqg->async_bfqq[i][j]);
-+
-+	__bfq_put_async_bfqq(bfqd, &bfqg->async_idle_bfqq);
-+}
-+
-+static void bfq_exit_queue(struct elevator_queue *e)
-+{
-+	struct bfq_data *bfqd = e->elevator_data;
-+	struct request_queue *q = bfqd->queue;
-+	struct bfq_queue *bfqq, *n;
-+
-+	bfq_shutdown_timer_wq(bfqd);
-+
-+	spin_lock_irq(q->queue_lock);
-+
-+	BUG_ON(bfqd->in_service_queue);
-+	list_for_each_entry_safe(bfqq, n, &bfqd->idle_list, bfqq_list)
-+		bfq_deactivate_bfqq(bfqd, bfqq, false, false);
-+
-+	spin_unlock_irq(q->queue_lock);
-+
-+	bfq_shutdown_timer_wq(bfqd);
-+
-+	BUG_ON(hrtimer_active(&bfqd->idle_slice_timer));
-+
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	blkcg_deactivate_policy(q, &blkcg_policy_bfq);
-+#else
-+	bfq_put_async_queues(bfqd, bfqd->root_group);
-+	kfree(bfqd->root_group);
-+#endif
-+
-+	kfree(bfqd);
-+}
-+
-+static void bfq_init_root_group(struct bfq_group *root_group,
-+				struct bfq_data *bfqd)
-+{
-+	int i;
-+
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	root_group->entity.parent = NULL;
-+	root_group->my_entity = NULL;
-+	root_group->bfqd = bfqd;
-+#endif
-+	root_group->rq_pos_tree = RB_ROOT;
-+	for (i = 0; i < BFQ_IOPRIO_CLASSES; i++)
-+		root_group->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT;
-+	root_group->sched_data.bfq_class_idle_last_service = jiffies;
-+}
-+
-+static int bfq_init_queue(struct request_queue *q, struct elevator_type *e)
-+{
-+	struct bfq_data *bfqd;
-+	struct elevator_queue *eq;
-+
-+	eq = elevator_alloc(q, e);
-+	if (!eq)
-+		return -ENOMEM;
-+
-+	bfqd = kzalloc_node(sizeof(*bfqd), GFP_KERNEL, q->node);
-+	if (!bfqd) {
-+		kobject_put(&eq->kobj);
-+		return -ENOMEM;
-+	}
-+	eq->elevator_data = bfqd;
-+
-+	/*
-+	 * Our fallback bfqq if bfq_find_alloc_queue() runs into OOM issues.
-+	 * Grab a permanent reference to it, so that the normal code flow
-+	 * will not attempt to free it.
-+	 */
-+	bfq_init_bfqq(bfqd, &bfqd->oom_bfqq, NULL, 1, 0);
-+	bfqd->oom_bfqq.ref++;
-+	bfqd->oom_bfqq.new_ioprio = BFQ_DEFAULT_QUEUE_IOPRIO;
-+	bfqd->oom_bfqq.new_ioprio_class = IOPRIO_CLASS_BE;
-+	bfqd->oom_bfqq.entity.new_weight =
-+		bfq_ioprio_to_weight(bfqd->oom_bfqq.new_ioprio);
-+
-+	/* oom_bfqq does not participate to bursts */
-+	bfq_clear_bfqq_just_created(&bfqd->oom_bfqq);
-+	/*
-+	 * Trigger weight initialization, according to ioprio, at the
-+	 * oom_bfqq's first activation. The oom_bfqq's ioprio and ioprio
-+	 * class won't be changed any more.
-+	 */
-+	bfqd->oom_bfqq.entity.prio_changed = 1;
-+
-+	bfqd->queue = q;
-+
-+	spin_lock_irq(q->queue_lock);
-+	q->elevator = eq;
-+	spin_unlock_irq(q->queue_lock);
-+
-+	bfqd->root_group = bfq_create_group_hierarchy(bfqd, q->node);
-+	if (!bfqd->root_group)
-+		goto out_free;
-+	bfq_init_root_group(bfqd->root_group, bfqd);
-+	bfq_init_entity(&bfqd->oom_bfqq.entity, bfqd->root_group);
-+
-+	hrtimer_init(&bfqd->idle_slice_timer, CLOCK_MONOTONIC,
-+		     HRTIMER_MODE_REL);
-+	bfqd->idle_slice_timer.function = bfq_idle_slice_timer;
-+
-+	bfqd->queue_weights_tree = RB_ROOT;
-+	bfqd->group_weights_tree = RB_ROOT;
-+
-+	INIT_WORK(&bfqd->unplug_work, bfq_kick_queue);
-+
-+	INIT_LIST_HEAD(&bfqd->active_list);
-+	INIT_LIST_HEAD(&bfqd->idle_list);
-+	INIT_HLIST_HEAD(&bfqd->burst_list);
-+
-+	bfqd->hw_tag = -1;
-+
-+	bfqd->bfq_max_budget = bfq_default_max_budget;
-+
-+	bfqd->bfq_fifo_expire[0] = bfq_fifo_expire[0];
-+	bfqd->bfq_fifo_expire[1] = bfq_fifo_expire[1];
-+	bfqd->bfq_back_max = bfq_back_max;
-+	bfqd->bfq_back_penalty = bfq_back_penalty;
-+	bfqd->bfq_slice_idle = bfq_slice_idle;
-+	bfqd->bfq_timeout = bfq_timeout;
-+
-+	bfqd->bfq_requests_within_timer = 120;
-+
-+	bfqd->bfq_large_burst_thresh = 8;
-+	bfqd->bfq_burst_interval = msecs_to_jiffies(180);
-+
-+	bfqd->low_latency = true;
-+
-+	/*
-+	 * Trade-off between responsiveness and fairness.
-+	 */
-+	bfqd->bfq_wr_coeff = 30;
-+	bfqd->bfq_wr_rt_max_time = msecs_to_jiffies(300);
-+	bfqd->bfq_wr_max_time = 0;
-+	bfqd->bfq_wr_min_idle_time = msecs_to_jiffies(2000);
-+	bfqd->bfq_wr_min_inter_arr_async = msecs_to_jiffies(500);
-+	bfqd->bfq_wr_max_softrt_rate = 7000; /*
-+					      * Approximate rate required
-+					      * to playback or record a
-+					      * high-definition compressed
-+					      * video.
-+					      */
-+	bfqd->wr_busy_queues = 0;
-+
-+	/*
-+	 * Begin by assuming, optimistically, that the device is a
-+	 * high-speed one, and that its peak rate is equal to 2/3 of
-+	 * the highest reference rate.
-+	 */
-+	bfqd->RT_prod = R_fast[blk_queue_nonrot(bfqd->queue)] *
-+			T_fast[blk_queue_nonrot(bfqd->queue)];
-+	bfqd->peak_rate = R_fast[blk_queue_nonrot(bfqd->queue)] * 2 / 3;
-+	bfqd->device_speed = BFQ_BFQD_FAST;
-+
-+	return 0;
-+
-+out_free:
-+	kfree(bfqd);
-+	kobject_put(&eq->kobj);
-+	return -ENOMEM;
-+}
-+
-+static void bfq_slab_kill(void)
-+{
-+	kmem_cache_destroy(bfq_pool);
-+}
-+
-+static int __init bfq_slab_setup(void)
-+{
-+	bfq_pool = KMEM_CACHE(bfq_queue, 0);
-+	if (!bfq_pool)
-+		return -ENOMEM;
-+	return 0;
-+}
-+
-+static ssize_t bfq_var_show(unsigned int var, char *page)
-+{
-+	return sprintf(page, "%u\n", var);
-+}
-+
-+static ssize_t bfq_var_store(unsigned long *var, const char *page,
-+			     size_t count)
-+{
-+	unsigned long new_val;
-+	int ret = kstrtoul(page, 10, &new_val);
-+
-+	if (ret == 0)
-+		*var = new_val;
-+
-+	return count;
-+}
-+
-+static ssize_t bfq_wr_max_time_show(struct elevator_queue *e, char *page)
-+{
-+	struct bfq_data *bfqd = e->elevator_data;
-+
-+	return sprintf(page, "%d\n", bfqd->bfq_wr_max_time > 0 ?
-+		       jiffies_to_msecs(bfqd->bfq_wr_max_time) :
-+		       jiffies_to_msecs(bfq_wr_duration(bfqd)));
-+}
-+
-+static ssize_t bfq_weights_show(struct elevator_queue *e, char *page)
-+{
-+	struct bfq_queue *bfqq;
-+	struct bfq_data *bfqd = e->elevator_data;
-+	ssize_t num_char = 0;
-+
-+	num_char += sprintf(page + num_char, "Tot reqs queued %d\n\n",
-+			    bfqd->queued);
-+
-+	spin_lock_irq(bfqd->queue->queue_lock);
-+
-+	num_char += sprintf(page + num_char, "Active:\n");
-+	list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list) {
-+		num_char += sprintf(page + num_char,
-+				    "pid%d: weight %hu, nr_queued %d %d, ",
-+				    bfqq->pid,
-+				    bfqq->entity.weight,
-+				    bfqq->queued[0],
-+				    bfqq->queued[1]);
-+		num_char += sprintf(page + num_char,
-+				    "dur %d/%u\n",
-+				    jiffies_to_msecs(
-+					    jiffies -
-+					    bfqq->last_wr_start_finish),
-+				    jiffies_to_msecs(bfqq->wr_cur_max_time));
-+	}
-+
-+	num_char += sprintf(page + num_char, "Idle:\n");
-+	list_for_each_entry(bfqq, &bfqd->idle_list, bfqq_list) {
-+		num_char += sprintf(page + num_char,
-+				    "pid%d: weight %hu, dur %d/%u\n",
-+				    bfqq->pid,
-+				    bfqq->entity.weight,
-+				    jiffies_to_msecs(jiffies -
-+						     bfqq->last_wr_start_finish),
-+				    jiffies_to_msecs(bfqq->wr_cur_max_time));
-+	}
-+
-+	spin_unlock_irq(bfqd->queue->queue_lock);
-+
-+	return num_char;
-+}
-+
-+#define SHOW_FUNCTION(__FUNC, __VAR, __CONV)				\
-+static ssize_t __FUNC(struct elevator_queue *e, char *page)		\
-+{									\
-+	struct bfq_data *bfqd = e->elevator_data;			\
-+	u64 __data = __VAR;						\
-+	if (__CONV == 1)						\
-+		__data = jiffies_to_msecs(__data);			\
-+	else if (__CONV == 2)						\
-+		__data = div_u64(__data, NSEC_PER_MSEC);		\
-+	return bfq_var_show(__data, (page));				\
-+}
-+SHOW_FUNCTION(bfq_fifo_expire_sync_show, bfqd->bfq_fifo_expire[1], 2);
-+SHOW_FUNCTION(bfq_fifo_expire_async_show, bfqd->bfq_fifo_expire[0], 2);
-+SHOW_FUNCTION(bfq_back_seek_max_show, bfqd->bfq_back_max, 0);
-+SHOW_FUNCTION(bfq_back_seek_penalty_show, bfqd->bfq_back_penalty, 0);
-+SHOW_FUNCTION(bfq_slice_idle_show, bfqd->bfq_slice_idle, 2);
-+SHOW_FUNCTION(bfq_max_budget_show, bfqd->bfq_user_max_budget, 0);
-+SHOW_FUNCTION(bfq_timeout_sync_show, bfqd->bfq_timeout, 1);
-+SHOW_FUNCTION(bfq_strict_guarantees_show, bfqd->strict_guarantees, 0);
-+SHOW_FUNCTION(bfq_low_latency_show, bfqd->low_latency, 0);
-+SHOW_FUNCTION(bfq_wr_coeff_show, bfqd->bfq_wr_coeff, 0);
-+SHOW_FUNCTION(bfq_wr_rt_max_time_show, bfqd->bfq_wr_rt_max_time, 1);
-+SHOW_FUNCTION(bfq_wr_min_idle_time_show, bfqd->bfq_wr_min_idle_time, 1);
-+SHOW_FUNCTION(bfq_wr_min_inter_arr_async_show, bfqd->bfq_wr_min_inter_arr_async,
-+	1);
-+SHOW_FUNCTION(bfq_wr_max_softrt_rate_show, bfqd->bfq_wr_max_softrt_rate, 0);
-+#undef SHOW_FUNCTION
-+
-+#define USEC_SHOW_FUNCTION(__FUNC, __VAR)				\
-+static ssize_t __FUNC(struct elevator_queue *e, char *page)		\
-+{									\
-+	struct bfq_data *bfqd = e->elevator_data;			\
-+	u64 __data = __VAR;						\
-+	__data = div_u64(__data, NSEC_PER_USEC);			\
-+	return bfq_var_show(__data, (page));				\
-+}
-+USEC_SHOW_FUNCTION(bfq_slice_idle_us_show, bfqd->bfq_slice_idle);
-+#undef USEC_SHOW_FUNCTION
-+
-+#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV)			\
-+static ssize_t								\
-+__FUNC(struct elevator_queue *e, const char *page, size_t count)	\
-+{									\
-+	struct bfq_data *bfqd = e->elevator_data;			\
-+	unsigned long uninitialized_var(__data);			\
-+	int ret = bfq_var_store(&__data, (page), count);		\
-+	if (__data < (MIN))						\
-+		__data = (MIN);						\
-+	else if (__data > (MAX))					\
-+		__data = (MAX);						\
-+	if (__CONV == 1)						\
-+		*(__PTR) = msecs_to_jiffies(__data);			\
-+	else if (__CONV == 2)						\
-+		*(__PTR) = (u64)__data * NSEC_PER_MSEC;			\
-+	else								\
-+		*(__PTR) = __data;					\
-+	return ret;							\
-+}
-+STORE_FUNCTION(bfq_fifo_expire_sync_store, &bfqd->bfq_fifo_expire[1], 1,
-+		INT_MAX, 2);
-+STORE_FUNCTION(bfq_fifo_expire_async_store, &bfqd->bfq_fifo_expire[0], 1,
-+		INT_MAX, 2);
-+STORE_FUNCTION(bfq_back_seek_max_store, &bfqd->bfq_back_max, 0, INT_MAX, 0);
-+STORE_FUNCTION(bfq_back_seek_penalty_store, &bfqd->bfq_back_penalty, 1,
-+		INT_MAX, 0);
-+STORE_FUNCTION(bfq_slice_idle_store, &bfqd->bfq_slice_idle, 0, INT_MAX, 2);
-+STORE_FUNCTION(bfq_wr_coeff_store, &bfqd->bfq_wr_coeff, 1, INT_MAX, 0);
-+STORE_FUNCTION(bfq_wr_max_time_store, &bfqd->bfq_wr_max_time, 0, INT_MAX, 1);
-+STORE_FUNCTION(bfq_wr_rt_max_time_store, &bfqd->bfq_wr_rt_max_time, 0, INT_MAX,
-+		1);
-+STORE_FUNCTION(bfq_wr_min_idle_time_store, &bfqd->bfq_wr_min_idle_time, 0,
-+		INT_MAX, 1);
-+STORE_FUNCTION(bfq_wr_min_inter_arr_async_store,
-+		&bfqd->bfq_wr_min_inter_arr_async, 0, INT_MAX, 1);
-+STORE_FUNCTION(bfq_wr_max_softrt_rate_store, &bfqd->bfq_wr_max_softrt_rate, 0,
-+		INT_MAX, 0);
-+#undef STORE_FUNCTION
-+
-+#define USEC_STORE_FUNCTION(__FUNC, __PTR, MIN, MAX)			\
-+static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count)\
-+{									\
-+	struct bfq_data *bfqd = e->elevator_data;			\
-+	unsigned long uninitialized_var(__data);			\
-+	int ret = bfq_var_store(&__data, (page), count);		\
-+	if (__data < (MIN))						\
-+		__data = (MIN);						\
-+	else if (__data > (MAX))					\
-+		__data = (MAX);						\
-+	*(__PTR) = (u64)__data * NSEC_PER_USEC;				\
-+	return ret;							\
-+}
-+USEC_STORE_FUNCTION(bfq_slice_idle_us_store, &bfqd->bfq_slice_idle, 0,
-+		    UINT_MAX);
-+#undef USEC_STORE_FUNCTION
-+
-+/* do nothing for the moment */
-+static ssize_t bfq_weights_store(struct elevator_queue *e,
-+				    const char *page, size_t count)
-+{
-+	return count;
-+}
-+
-+static ssize_t bfq_max_budget_store(struct elevator_queue *e,
-+				    const char *page, size_t count)
-+{
-+	struct bfq_data *bfqd = e->elevator_data;
-+	unsigned long uninitialized_var(__data);
-+	int ret = bfq_var_store(&__data, (page), count);
-+
-+	if (__data == 0)
-+		bfqd->bfq_max_budget = bfq_calc_max_budget(bfqd);
-+	else {
-+		if (__data > INT_MAX)
-+			__data = INT_MAX;
-+		bfqd->bfq_max_budget = __data;
-+	}
-+
-+	bfqd->bfq_user_max_budget = __data;
-+
-+	return ret;
-+}
-+
-+/*
-+ * Leaving this name to preserve name compatibility with cfq
-+ * parameters, but this timeout is used for both sync and async.
-+ */
-+static ssize_t bfq_timeout_sync_store(struct elevator_queue *e,
-+				      const char *page, size_t count)
-+{
-+	struct bfq_data *bfqd = e->elevator_data;
-+	unsigned long uninitialized_var(__data);
-+	int ret = bfq_var_store(&__data, (page), count);
-+
-+	if (__data < 1)
-+		__data = 1;
-+	else if (__data > INT_MAX)
-+		__data = INT_MAX;
-+
-+	bfqd->bfq_timeout = msecs_to_jiffies(__data);
-+	if (bfqd->bfq_user_max_budget == 0)
-+		bfqd->bfq_max_budget = bfq_calc_max_budget(bfqd);
-+
-+	return ret;
-+}
-+
-+static ssize_t bfq_strict_guarantees_store(struct elevator_queue *e,
-+				     const char *page, size_t count)
-+{
-+	struct bfq_data *bfqd = e->elevator_data;
-+	unsigned long uninitialized_var(__data);
-+	int ret = bfq_var_store(&__data, (page), count);
-+
-+	if (__data > 1)
-+		__data = 1;
-+	if (!bfqd->strict_guarantees && __data == 1
-+	    && bfqd->bfq_slice_idle < 8 * NSEC_PER_MSEC)
-+		bfqd->bfq_slice_idle = 8 * NSEC_PER_MSEC;
-+
-+	bfqd->strict_guarantees = __data;
-+
-+	return ret;
-+}
-+
-+static ssize_t bfq_low_latency_store(struct elevator_queue *e,
-+				     const char *page, size_t count)
-+{
-+	struct bfq_data *bfqd = e->elevator_data;
-+	unsigned long uninitialized_var(__data);
-+	int ret = bfq_var_store(&__data, (page), count);
-+
-+	if (__data > 1)
-+		__data = 1;
-+	if (__data == 0 && bfqd->low_latency != 0)
-+		bfq_end_wr(bfqd);
-+	bfqd->low_latency = __data;
-+
-+	return ret;
-+}
-+
-+#define BFQ_ATTR(name) \
-+	__ATTR(name, S_IRUGO|S_IWUSR, bfq_##name##_show, bfq_##name##_store)
-+
-+static struct elv_fs_entry bfq_attrs[] = {
-+	BFQ_ATTR(fifo_expire_sync),
-+	BFQ_ATTR(fifo_expire_async),
-+	BFQ_ATTR(back_seek_max),
-+	BFQ_ATTR(back_seek_penalty),
-+	BFQ_ATTR(slice_idle),
-+	BFQ_ATTR(slice_idle_us),
-+	BFQ_ATTR(max_budget),
-+	BFQ_ATTR(timeout_sync),
-+	BFQ_ATTR(strict_guarantees),
-+	BFQ_ATTR(low_latency),
-+	BFQ_ATTR(wr_coeff),
-+	BFQ_ATTR(wr_max_time),
-+	BFQ_ATTR(wr_rt_max_time),
-+	BFQ_ATTR(wr_min_idle_time),
-+	BFQ_ATTR(wr_min_inter_arr_async),
-+	BFQ_ATTR(wr_max_softrt_rate),
-+	BFQ_ATTR(weights),
-+	__ATTR_NULL
-+};
-+
-+static struct elevator_type iosched_bfq = {
-+	.ops.sq = {
-+		.elevator_merge_fn =		bfq_merge,
-+		.elevator_merged_fn =		bfq_merged_request,
-+		.elevator_merge_req_fn =	bfq_merged_requests,
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+		.elevator_bio_merged_fn =	bfq_bio_merged,
-+#endif
-+		.elevator_allow_bio_merge_fn =	bfq_allow_bio_merge,
-+		.elevator_allow_rq_merge_fn =	bfq_allow_rq_merge,
-+		.elevator_dispatch_fn =		bfq_dispatch_requests,
-+		.elevator_add_req_fn =		bfq_insert_request,
-+		.elevator_activate_req_fn =	bfq_activate_request,
-+		.elevator_deactivate_req_fn =	bfq_deactivate_request,
-+		.elevator_completed_req_fn =	bfq_completed_request,
-+		.elevator_former_req_fn =	elv_rb_former_request,
-+		.elevator_latter_req_fn =	elv_rb_latter_request,
-+		.elevator_init_icq_fn =		bfq_init_icq,
-+		.elevator_exit_icq_fn =		bfq_exit_icq,
-+		.elevator_set_req_fn =		bfq_set_request,
-+		.elevator_put_req_fn =		bfq_put_request,
-+		.elevator_may_queue_fn =	bfq_may_queue,
-+		.elevator_init_fn =		bfq_init_queue,
-+		.elevator_exit_fn =		bfq_exit_queue,
-+	},
-+	.icq_size =		sizeof(struct bfq_io_cq),
-+	.icq_align =		__alignof__(struct bfq_io_cq),
-+	.elevator_attrs =	bfq_attrs,
-+	.elevator_name =	"bfq-sq",
-+	.elevator_owner =	THIS_MODULE,
-+};
-+
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+static struct blkcg_policy blkcg_policy_bfq = {
-+	.dfl_cftypes		= bfq_blkg_files,
-+	.legacy_cftypes		= bfq_blkcg_legacy_files,
-+
-+	.cpd_alloc_fn		= bfq_cpd_alloc,
-+	.cpd_init_fn		= bfq_cpd_init,
-+	.cpd_bind_fn	        = bfq_cpd_init,
-+	.cpd_free_fn		= bfq_cpd_free,
-+
-+	.pd_alloc_fn		= bfq_pd_alloc,
-+	.pd_init_fn		= bfq_pd_init,
-+	.pd_offline_fn		= bfq_pd_offline,
-+	.pd_free_fn		= bfq_pd_free,
-+	.pd_reset_stats_fn	= bfq_pd_reset_stats,
-+};
-+#endif
-+
-+static int __init bfq_init(void)
-+{
-+	int ret;
-+	char msg[60] = "BFQ I/O-scheduler: v8r12";
-+
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	ret = blkcg_policy_register(&blkcg_policy_bfq);
-+	if (ret)
-+		return ret;
-+#endif
-+
-+	ret = -ENOMEM;
-+	if (bfq_slab_setup())
-+		goto err_pol_unreg;
-+
-+	/*
-+	 * Times to load large popular applications for the typical
-+	 * systems installed on the reference devices (see the
-+	 * comments before the definitions of the next two
-+	 * arrays). Actually, we use slightly slower values, as the
-+	 * estimated peak rate tends to be smaller than the actual
-+	 * peak rate.  The reason for this last fact is that estimates
-+	 * are computed over much shorter time intervals than the long
-+	 * intervals typically used for benchmarking. Why? First, to
-+	 * adapt more quickly to variations. Second, because an I/O
-+	 * scheduler cannot rely on a peak-rate-evaluation workload to
-+	 * be run for a long time.
-+	 */
-+	T_slow[0] = msecs_to_jiffies(3500); /* actually 4 sec */
-+	T_slow[1] = msecs_to_jiffies(6000); /* actually 6.5 sec */
-+	T_fast[0] = msecs_to_jiffies(7000); /* actually 8 sec */
-+	T_fast[1] = msecs_to_jiffies(2500); /* actually 3 sec */
-+
-+	/*
-+	 * Thresholds that determine the switch between speed classes
-+	 * (see the comments before the definition of the array
-+	 * device_speed_thresh). These thresholds are biased towards
-+	 * transitions to the fast class. This is safer than the
-+	 * opposite bias. In fact, a wrong transition to the slow
-+	 * class results in short weight-raising periods, because the
-+	 * speed of the device then tends to be higher that the
-+	 * reference peak rate. On the opposite end, a wrong
-+	 * transition to the fast class tends to increase
-+	 * weight-raising periods, because of the opposite reason.
-+	 */
-+	device_speed_thresh[0] = (4 * R_slow[0]) / 3;
-+	device_speed_thresh[1] = (4 * R_slow[1]) / 3;
-+
-+	ret = elv_register(&iosched_bfq);
-+	if (ret)
-+		goto err_pol_unreg;
-+
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	strcat(msg, " (with cgroups support)");
-+#endif
-+	pr_info("%s", msg);
-+
-+	return 0;
-+
-+err_pol_unreg:
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	blkcg_policy_unregister(&blkcg_policy_bfq);
-+#endif
-+	return ret;
-+}
-+
-+static void __exit bfq_exit(void)
-+{
-+	elv_unregister(&iosched_bfq);
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+	blkcg_policy_unregister(&blkcg_policy_bfq);
-+#endif
-+	bfq_slab_kill();
-+}
-+
-+module_init(bfq_init);
-+module_exit(bfq_exit);
-+
-+MODULE_AUTHOR("Arianna Avanzini, Fabio Checconi, Paolo Valente");
-+MODULE_LICENSE("GPL");
-
-From e24d2e6461479dbd13d58be2dc44b23b5e24487c Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Mon, 19 Dec 2016 17:13:39 +0100
-Subject: [PATCH 07/51] Add config and build bits for bfq-mq-iosched
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/Kconfig.iosched       | 10 +++++++++
- block/Makefile              |  1 +
- block/bfq-cgroup-included.c |  4 ++--
- block/bfq-mq-iosched.c      | 25 ++++++++++++-----------
- block/bfq-sched.c           | 50 ++++++++++++++++++++++-----------------------
- block/bfq-sq-iosched.c      | 24 +++++++++++-----------
- block/bfq.h                 | 36 +++++++++++++++++++++-----------
- 8 files changed, 88 insertions(+), 64 deletions(-)
-
-diff --git a/block/Kconfig.iosched b/block/Kconfig.iosched
-index 9e3f4c2f7390..2d94af3d8b0a 100644
---- a/block/Kconfig.iosched
-+++ b/block/Kconfig.iosched
-@@ -96,6 +96,16 @@ config DEFAULT_IOSCHED
- 	default "bfq-sq" if DEFAULT_BFQ_SQ
- 	default "noop" if DEFAULT_NOOP
- 
-+config MQ_IOSCHED_BFQ
-+	tristate "BFQ-MQ I/O Scheduler"
-+	default y
-+	---help---
-+	BFQ I/O scheduler for BLK-MQ. BFQ-MQ distributes bandwidth
-+	among all processes according to their weights, regardless of
-+	the device parameters and with any workload. It also
-+	guarantees a low latency to interactive and soft real-time
-+	applications.  Details in Documentation/block/bfq-iosched.txt
-+
- config MQ_IOSCHED_DEADLINE
- 	tristate "MQ deadline I/O scheduler"
- 	default y
-diff --git a/block/Makefile b/block/Makefile
-index 59026b425791..a571329c23f0 100644
---- a/block/Makefile
-+++ b/block/Makefile
-@@ -25,6 +25,7 @@ obj-$(CONFIG_MQ_IOSCHED_KYBER)	+= kyber-iosched.o
- bfq-y				:= bfq-iosched.o bfq-wf2q.o bfq-cgroup.o
- obj-$(CONFIG_IOSCHED_BFQ)	+= bfq.o
- obj-$(CONFIG_IOSCHED_BFQ_SQ)	+= bfq-sq-iosched.o
-+obj-$(CONFIG_MQ_IOSCHED_BFQ)	+= bfq-mq-iosched.o
- 
- obj-$(CONFIG_BLOCK_COMPAT)	+= compat_ioctl.o
- obj-$(CONFIG_BLK_CMDLINE_PARSER)	+= cmdline-parser.o
-diff --git a/block/bfq-cgroup-included.c b/block/bfq-cgroup-included.c
-index af7c216a3540..9c483b658179 100644
---- a/block/bfq-cgroup-included.c
-+++ b/block/bfq-cgroup-included.c
-@@ -15,7 +15,7 @@
-  * file.
-  */
- 
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 
- /* bfqg stats flags */
- enum bfqg_stats_flags {
-@@ -1116,7 +1116,7 @@ static struct cftype bfq_blkg_files[] = {
- 	{} /* terminate */
- };
- 
--#else /* CONFIG_BFQ_SQ_GROUP_IOSCHED */
-+#else /* BFQ_GROUP_IOSCHED_ENABLED */
- 
- static inline void bfqg_stats_update_io_add(struct bfq_group *bfqg,
- 			struct bfq_queue *bfqq, unsigned int op) { }
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 30d019fc67e0..e88e00f1e0a7 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -82,6 +82,7 @@
- #include <linux/rbtree.h>
- #include <linux/ioprio.h>
- #include "blk.h"
-+#undef CONFIG_BFQ_GROUP_IOSCHED /* cgroups support not yet functional */
- #include "bfq.h"
- 
- /* Expiration time of sync (0) and async (1) requests, in ns. */
-@@ -387,7 +388,7 @@ static bool bfq_differentiated_weights(struct bfq_data *bfqd)
- 	return (!RB_EMPTY_ROOT(&bfqd->queue_weights_tree) &&
- 		(bfqd->queue_weights_tree.rb_node->rb_left ||
- 		 bfqd->queue_weights_tree.rb_node->rb_right)
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	       ) ||
- 	       (!RB_EMPTY_ROOT(&bfqd->group_weights_tree) &&
- 		(bfqd->group_weights_tree.rb_node->rb_left ||
-@@ -1672,7 +1673,7 @@ static void bfq_merged_request(struct request_queue *q, struct request *req,
- 	}
- }
- 
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- static void bfq_bio_merged(struct request_queue *q, struct request *req,
- 			   struct bio *bio)
- {
-@@ -3879,7 +3880,7 @@ static int bfq_dispatch_requests(struct request_queue *q, int force)
-  */
- static void bfq_put_queue(struct bfq_queue *bfqq)
- {
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	struct bfq_group *bfqg = bfqq_group(bfqq);
- #endif
- 
-@@ -3909,7 +3910,7 @@ static void bfq_put_queue(struct bfq_queue *bfqq)
- 	bfq_log_bfqq(bfqq->bfqd, bfqq, "put_queue: %p freed", bfqq);
- 
- 	kmem_cache_free(bfq_pool, bfqq);
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	bfqg_put(bfqg);
- #endif
- }
-@@ -4835,7 +4836,7 @@ static void bfq_exit_queue(struct elevator_queue *e)
- 
- 	BUG_ON(hrtimer_active(&bfqd->idle_slice_timer));
- 
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	blkcg_deactivate_policy(q, &blkcg_policy_bfq);
- #else
- 	bfq_put_async_queues(bfqd, bfqd->root_group);
-@@ -4850,7 +4851,7 @@ static void bfq_init_root_group(struct bfq_group *root_group,
- {
- 	int i;
- 
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	root_group->entity.parent = NULL;
- 	root_group->my_entity = NULL;
- 	root_group->bfqd = bfqd;
-@@ -5265,7 +5266,7 @@ static struct elevator_type iosched_bfq = {
- 		.elevator_merge_fn =		bfq_merge,
- 		.elevator_merged_fn =		bfq_merged_request,
- 		.elevator_merge_req_fn =	bfq_merged_requests,
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 		.elevator_bio_merged_fn =	bfq_bio_merged,
- #endif
- 		.elevator_allow_bio_merge_fn =	bfq_allow_bio_merge,
-@@ -5292,7 +5293,7 @@ static struct elevator_type iosched_bfq = {
- 	.elevator_owner =	THIS_MODULE,
- };
- 
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- static struct blkcg_policy blkcg_policy_bfq = {
- 	.dfl_cftypes		= bfq_blkg_files,
- 	.legacy_cftypes		= bfq_blkcg_legacy_files,
-@@ -5315,7 +5316,7 @@ static int __init bfq_init(void)
- 	int ret;
- 	char msg[60] = "BFQ I/O-scheduler: v8r12";
- 
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	ret = blkcg_policy_register(&blkcg_policy_bfq);
- 	if (ret)
- 		return ret;
-@@ -5362,7 +5363,7 @@ static int __init bfq_init(void)
- 	if (ret)
- 		goto err_pol_unreg;
- 
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	strcat(msg, " (with cgroups support)");
- #endif
- 	pr_info("%s", msg);
-@@ -5370,7 +5371,7 @@ static int __init bfq_init(void)
- 	return 0;
- 
- err_pol_unreg:
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	blkcg_policy_unregister(&blkcg_policy_bfq);
- #endif
- 	return ret;
-@@ -5379,7 +5380,7 @@ static int __init bfq_init(void)
- static void __exit bfq_exit(void)
- {
- 	elv_unregister(&iosched_bfq);
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	blkcg_policy_unregister(&blkcg_policy_bfq);
- #endif
- 	bfq_slab_kill();
-diff --git a/block/bfq-sched.c b/block/bfq-sched.c
-index 5c0f9290a79c..b54a638186e3 100644
---- a/block/bfq-sched.c
-+++ b/block/bfq-sched.c
-@@ -136,7 +136,7 @@ static bool bfq_update_next_in_service(struct bfq_sched_data *sd,
- 	if (bfqq)
- 		bfq_log_bfqq(bfqq->bfqd, bfqq,
- 			     "update_next_in_service: chosen this queue");
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	else {
- 		struct bfq_group *bfqg =
- 			container_of(next_in_service,
-@@ -149,7 +149,7 @@ static bool bfq_update_next_in_service(struct bfq_sched_data *sd,
- 	return parent_sched_may_change;
- }
- 
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- /* both next loops stop at one of the child entities of the root group */
- #define for_each_entity(entity)				\
- 	for (; entity ; entity = entity->parent)
-@@ -243,7 +243,7 @@ static bool bfq_no_longer_next_in_service(struct bfq_entity *entity)
- 	return false;
- }
- 
--#else /* CONFIG_BFQ_SQ_GROUP_IOSCHED */
-+#else /* BFQ_GROUP_IOSCHED_ENABLED */
- #define for_each_entity(entity)	\
- 	for (; entity ; entity = NULL)
- 
-@@ -260,7 +260,7 @@ static bool bfq_no_longer_next_in_service(struct bfq_entity *entity)
- 	return true;
- }
- 
--#endif /* CONFIG_BFQ_SQ_GROUP_IOSCHED */
-+#endif /* BFQ_GROUP_IOSCHED_ENABLED */
- 
- /*
-  * Shift for timestamp calculations.  This actually limits the maximum
-@@ -323,7 +323,7 @@ static void bfq_calc_finish(struct bfq_entity *entity, unsigned long service)
- 		bfq_log_bfqq(bfqq->bfqd, bfqq,
- 			"calc_finish: start %llu, finish %llu, delta %llu",
- 			start, finish, delta);
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	} else {
- 		struct bfq_group *bfqg =
- 			container_of(entity, struct bfq_group, entity);
-@@ -473,7 +473,7 @@ static void bfq_update_active_node(struct rb_node *node)
- 		bfq_log_bfqq(bfqq->bfqd, bfqq,
- 			     "update_active_node: new min_start %llu",
- 			     ((entity->min_start>>10)*1000)>>12);
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	} else {
- 		struct bfq_group *bfqg =
- 			container_of(entity, struct bfq_group, entity);
-@@ -540,7 +540,7 @@ static void bfq_active_insert(struct bfq_service_tree *st,
- {
- 	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
- 	struct rb_node *node = &entity->rb_node;
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	struct bfq_sched_data *sd = NULL;
- 	struct bfq_group *bfqg = NULL;
- 	struct bfq_data *bfqd = NULL;
-@@ -555,7 +555,7 @@ static void bfq_active_insert(struct bfq_service_tree *st,
- 
- 	bfq_update_active_tree(node);
- 
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	sd = entity->sched_data;
- 	bfqg = container_of(sd, struct bfq_group, sched_data);
- 	BUG_ON(!bfqg);
-@@ -563,7 +563,7 @@ static void bfq_active_insert(struct bfq_service_tree *st,
- #endif
- 	if (bfqq)
- 		list_add(&bfqq->bfqq_list, &bfqq->bfqd->active_list);
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	else { /* bfq_group */
- 		BUG_ON(!bfqd);
- 		bfq_weights_tree_add(bfqd, entity, &bfqd->group_weights_tree);
-@@ -652,7 +652,7 @@ static void bfq_active_extract(struct bfq_service_tree *st,
- {
- 	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
- 	struct rb_node *node;
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	struct bfq_sched_data *sd = NULL;
- 	struct bfq_group *bfqg = NULL;
- 	struct bfq_data *bfqd = NULL;
-@@ -664,7 +664,7 @@ static void bfq_active_extract(struct bfq_service_tree *st,
- 	if (node)
- 		bfq_update_active_tree(node);
- 
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	sd = entity->sched_data;
- 	bfqg = container_of(sd, struct bfq_group, sched_data);
- 	BUG_ON(!bfqg);
-@@ -672,7 +672,7 @@ static void bfq_active_extract(struct bfq_service_tree *st,
- #endif
- 	if (bfqq)
- 		list_del(&bfqq->bfqq_list);
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	else { /* bfq_group */
- 		BUG_ON(!bfqd);
- 		bfq_weights_tree_remove(bfqd, entity,
-@@ -809,14 +809,14 @@ __bfq_entity_update_weight_prio(struct bfq_service_tree *old_st,
- 		unsigned int prev_weight, new_weight;
- 		struct bfq_data *bfqd = NULL;
- 		struct rb_root *root;
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 		struct bfq_sched_data *sd;
- 		struct bfq_group *bfqg;
- #endif
- 
- 		if (bfqq)
- 			bfqd = bfqq->bfqd;
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 		else {
- 			sd = entity->my_sched_data;
- 			bfqg = container_of(sd, struct bfq_group, sched_data);
-@@ -907,7 +907,7 @@ __bfq_entity_update_weight_prio(struct bfq_service_tree *old_st,
- 	return new_st;
- }
- 
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- static void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg);
- #endif
- 
-@@ -936,7 +936,7 @@ static void bfq_bfqq_served(struct bfq_queue *bfqq, int served)
- 		st->vtime += bfq_delta(served, st->wsum);
- 		bfq_forget_idle(st);
- 	}
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	bfqg_stats_set_start_empty_time(bfqq_group(bfqq));
- #endif
- 	st = bfq_entity_service_tree(&bfqq->entity);
-@@ -1060,7 +1060,7 @@ static void bfq_update_fin_time_enqueue(struct bfq_entity *entity,
- 			bfq_log_bfqq(bfqq->bfqd, bfqq,
- 				     "__activate_entity: new queue finish %llu",
- 				     ((entity->finish>>10)*1000)>>12);
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 		} else {
- 			struct bfq_group *bfqg =
- 				container_of(entity, struct bfq_group, entity);
-@@ -1078,7 +1078,7 @@ static void bfq_update_fin_time_enqueue(struct bfq_entity *entity,
- 		bfq_log_bfqq(bfqq->bfqd, bfqq,
- 			"__activate_entity: queue %seligible in st %p",
- 			     entity->start <= st->vtime ? "" : "non ", st);
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	} else {
- 		struct bfq_group *bfqg =
- 			container_of(entity, struct bfq_group, entity);
-@@ -1153,7 +1153,7 @@ static void __bfq_activate_entity(struct bfq_entity *entity,
- 
- 		BUG_ON(entity->on_st && bfqq);
- 
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 		if (entity->on_st && !bfqq) {
- 			struct bfq_group *bfqg =
- 				container_of(entity, struct bfq_group,
-@@ -1485,7 +1485,7 @@ static void bfq_deactivate_entity(struct bfq_entity *entity,
- 		if (bfqq)
- 			bfq_log_bfqq(bfqq->bfqd, bfqq,
- 				     "invoking udpdate_next for this queue");
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 		else {
- 			struct bfq_group *bfqg =
- 				container_of(entity,
-@@ -1525,7 +1525,7 @@ static u64 bfq_calc_vtime_jump(struct bfq_service_tree *st)
- 			bfq_log_bfqq(bfqq->bfqd, bfqq,
- 				     "calc_vtime_jump: new value %llu",
- 				     root_entity->min_start);
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 		else {
- 			struct bfq_group *bfqg =
- 				container_of(root_entity, struct bfq_group,
-@@ -1661,7 +1661,7 @@ __bfq_lookup_next_entity(struct bfq_service_tree *st, bool in_service
- 			     "__lookup_next: start %llu vtime %llu st %p",
- 			     ((entity->start>>10)*1000)>>12,
- 			     ((new_vtime>>10)*1000)>>12, st);
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	else {
- 		struct bfq_group *bfqg =
- 			container_of(entity, struct bfq_group, entity);
-@@ -1735,7 +1735,7 @@ static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd)
- 	if (bfqq)
- 		bfq_log_bfqq(bfqq->bfqd, bfqq, "chosen from st %p %d",
- 			     st + class_idx, class_idx);
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	else {
- 		struct bfq_group *bfqg =
- 			container_of(entity, struct bfq_group, entity);
-@@ -1777,7 +1777,7 @@ static struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd)
- 	 */
- 	sd = &bfqd->root_group->sched_data;
- 	for (; sd ; sd = entity->my_sched_data) {
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 		if (entity) {
- 			struct bfq_group *bfqg =
- 				container_of(entity, struct bfq_group, entity);
-@@ -1867,7 +1867,7 @@ static struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd)
- 			bfq_log_bfqq(bfqd, bfqq,
- 			     "get_next_queue: this queue, finish %llu",
- 				(((entity->finish>>10)*1000)>>10)>>2);
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 		else {
- 			struct bfq_group *bfqg =
- 				container_of(entity, struct bfq_group, entity);
-diff --git a/block/bfq-sq-iosched.c b/block/bfq-sq-iosched.c
-index 30d019fc67e0..25da0d1c0622 100644
---- a/block/bfq-sq-iosched.c
-+++ b/block/bfq-sq-iosched.c
-@@ -387,7 +387,7 @@ static bool bfq_differentiated_weights(struct bfq_data *bfqd)
- 	return (!RB_EMPTY_ROOT(&bfqd->queue_weights_tree) &&
- 		(bfqd->queue_weights_tree.rb_node->rb_left ||
- 		 bfqd->queue_weights_tree.rb_node->rb_right)
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	       ) ||
- 	       (!RB_EMPTY_ROOT(&bfqd->group_weights_tree) &&
- 		(bfqd->group_weights_tree.rb_node->rb_left ||
-@@ -1672,7 +1672,7 @@ static void bfq_merged_request(struct request_queue *q, struct request *req,
- 	}
- }
- 
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- static void bfq_bio_merged(struct request_queue *q, struct request *req,
- 			   struct bio *bio)
- {
-@@ -3879,7 +3879,7 @@ static int bfq_dispatch_requests(struct request_queue *q, int force)
-  */
- static void bfq_put_queue(struct bfq_queue *bfqq)
- {
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	struct bfq_group *bfqg = bfqq_group(bfqq);
- #endif
- 
-@@ -3909,7 +3909,7 @@ static void bfq_put_queue(struct bfq_queue *bfqq)
- 	bfq_log_bfqq(bfqq->bfqd, bfqq, "put_queue: %p freed", bfqq);
- 
- 	kmem_cache_free(bfq_pool, bfqq);
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	bfqg_put(bfqg);
- #endif
- }
-@@ -4835,7 +4835,7 @@ static void bfq_exit_queue(struct elevator_queue *e)
- 
- 	BUG_ON(hrtimer_active(&bfqd->idle_slice_timer));
- 
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	blkcg_deactivate_policy(q, &blkcg_policy_bfq);
- #else
- 	bfq_put_async_queues(bfqd, bfqd->root_group);
-@@ -4850,7 +4850,7 @@ static void bfq_init_root_group(struct bfq_group *root_group,
- {
- 	int i;
- 
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	root_group->entity.parent = NULL;
- 	root_group->my_entity = NULL;
- 	root_group->bfqd = bfqd;
-@@ -5265,7 +5265,7 @@ static struct elevator_type iosched_bfq = {
- 		.elevator_merge_fn =		bfq_merge,
- 		.elevator_merged_fn =		bfq_merged_request,
- 		.elevator_merge_req_fn =	bfq_merged_requests,
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 		.elevator_bio_merged_fn =	bfq_bio_merged,
- #endif
- 		.elevator_allow_bio_merge_fn =	bfq_allow_bio_merge,
-@@ -5292,7 +5292,7 @@ static struct elevator_type iosched_bfq = {
- 	.elevator_owner =	THIS_MODULE,
- };
- 
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- static struct blkcg_policy blkcg_policy_bfq = {
- 	.dfl_cftypes		= bfq_blkg_files,
- 	.legacy_cftypes		= bfq_blkcg_legacy_files,
-@@ -5315,7 +5315,7 @@ static int __init bfq_init(void)
- 	int ret;
- 	char msg[60] = "BFQ I/O-scheduler: v8r12";
- 
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	ret = blkcg_policy_register(&blkcg_policy_bfq);
- 	if (ret)
- 		return ret;
-@@ -5362,7 +5362,7 @@ static int __init bfq_init(void)
- 	if (ret)
- 		goto err_pol_unreg;
- 
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	strcat(msg, " (with cgroups support)");
- #endif
- 	pr_info("%s", msg);
-@@ -5370,7 +5370,7 @@ static int __init bfq_init(void)
- 	return 0;
- 
- err_pol_unreg:
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	blkcg_policy_unregister(&blkcg_policy_bfq);
- #endif
- 	return ret;
-@@ -5379,7 +5379,7 @@ static int __init bfq_init(void)
- static void __exit bfq_exit(void)
- {
- 	elv_unregister(&iosched_bfq);
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	blkcg_policy_unregister(&blkcg_policy_bfq);
- #endif
- 	bfq_slab_kill();
-diff --git a/block/bfq.h b/block/bfq.h
-index 34fc4697fd89..53954d1b87f8 100644
---- a/block/bfq.h
-+++ b/block/bfq.h
-@@ -19,6 +19,18 @@
- #include <linux/hrtimer.h>
- #include <linux/blk-cgroup.h>
- 
-+/*
-+ * Define an alternative macro to compile cgroups support. This is one
-+ * of the steps needed to let bfq-mq share the files bfq-sched.c and
-+ * bfq-cgroup.c with bfq-sq. For bfq-mq, the macro
-+ * BFQ_GROUP_IOSCHED_ENABLED will be defined as a function of whether
-+ * the configuration option CONFIG_BFQ_MQ_GROUP_IOSCHED, and not
-+ * CONFIG_BFQ_GROUP_IOSCHED, is defined.
-+ */
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#define BFQ_GROUP_IOSCHED_ENABLED
-+#endif
-+
- #define BFQ_IOPRIO_CLASSES	3
- #define BFQ_CL_IDLE_TIMEOUT	(HZ/5)
- 
-@@ -344,7 +356,7 @@ struct bfq_io_cq {
- 	struct bfq_ttime ttime;
- 	/* per (request_queue, blkcg) ioprio */
- 	int ioprio;
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	uint64_t blkcg_serial_nr; /* the current blkcg serial */
- #endif
- 
-@@ -671,7 +683,7 @@ static const char *checked_dev_name(const struct device *dev)
- 	return nodev;
- }
- 
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- static struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
- static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
- 
-@@ -696,7 +708,7 @@ static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
- 	__pbuf, ##args);						\
- } while (0)
- 
--#else /* CONFIG_BFQ_SQ_GROUP_IOSCHED */
-+#else /* BFQ_GROUP_IOSCHED_ENABLED */
- 
- #define bfq_log_bfqq(bfqd, bfqq, fmt, args...)				\
- 	pr_crit("%s bfq%d%c " fmt "\n",					\
-@@ -705,7 +717,7 @@ static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
- 		##args)
- #define bfq_log_bfqg(bfqd, bfqg, fmt, args...)		do {} while (0)
- 
--#endif /* CONFIG_BFQ_SQ_GROUP_IOSCHED */
-+#endif /* BFQ_GROUP_IOSCHED_ENABLED */
- 
- #define bfq_log(bfqd, fmt, args...) \
- 	pr_crit("%s bfq " fmt "\n",					\
-@@ -713,7 +725,7 @@ static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
- 		##args)
- 
- #else /* CONFIG_BFQ_REDIRECT_TO_CONSOLE */
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- static struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
- static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
- 
-@@ -735,7 +747,7 @@ static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
- 	blk_add_trace_msg((bfqd)->queue, "%s " fmt, __pbuf, ##args);	\
- } while (0)
- 
--#else /* CONFIG_BFQ_SQ_GROUP_IOSCHED */
-+#else /* BFQ_GROUP_IOSCHED_ENABLED */
- 
- #define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	\
- 	blk_add_trace_msg((bfqd)->queue, "bfq%d%c " fmt, (bfqq)->pid,	\
-@@ -743,7 +755,7 @@ static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
- 				##args)
- #define bfq_log_bfqg(bfqd, bfqg, fmt, args...)		do {} while (0)
- 
--#endif /* CONFIG_BFQ_SQ_GROUP_IOSCHED */
-+#endif /* BFQ_GROUP_IOSCHED_ENABLED */
- 
- #define bfq_log(bfqd, fmt, args...) \
- 	blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args)
-@@ -763,7 +775,7 @@ enum bfqq_expiration {
- 
- 
- struct bfqg_stats {
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	/* number of ios merged */
- 	struct blkg_rwstat		merged;
- 	/* total time spent on device in ns, may not be accurate w/ queueing */
-@@ -794,7 +806,7 @@ struct bfqg_stats {
- #endif
- };
- 
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- /*
-  * struct bfq_group_data - per-blkcg storage for the blkio subsystem.
-  *
-@@ -895,7 +907,7 @@ bfq_entity_service_tree(struct bfq_entity *entity)
- 		bfq_log_bfqq(bfqq->bfqd, bfqq,
- 			     "entity_service_tree %p %d",
- 			     sched_data->service_tree + idx, idx);
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	else {
- 		struct bfq_group *bfqg =
- 			container_of(entity, struct bfq_group, entity);
-@@ -924,7 +936,7 @@ static struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic)
- 	return bic->icq.q->elevator->elevator_data;
- }
- 
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 
- static struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq)
- {
-@@ -953,7 +965,7 @@ static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd,
- 				       struct bfq_io_cq *bic);
- static void bfq_end_wr_async_queues(struct bfq_data *bfqd,
- 				    struct bfq_group *bfqg);
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);
- #endif
- static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq);
-
-From add91dbd756cf8ca3aa3add9a19eef742d5fca6b Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Fri, 20 Jan 2017 09:18:25 +0100
-Subject: [PATCH 08/51] Increase max policies for io controller
-
-To let bfq-mq policy be plugged too (however cgroups
-suppport is not yet functional in bfq-mq).
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- include/linux/blkdev.h | 2 +-
- 1 file changed, 1 insertion(+), 1 deletion(-)
-
-diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
-index bf000c58644b..10f892ca585d 100644
---- a/include/linux/blkdev.h
-+++ b/include/linux/blkdev.h
-@@ -54,7 +54,7 @@ struct blk_stat_callback;
-  * Maximum number of blkcg policies allowed to be registered concurrently.
-  * Defined here to simplify include dependency.
-  */
--#define BLKCG_MAX_POLS		4
-+#define BLKCG_MAX_POLS		5
- 
- typedef void (rq_end_io_fn)(struct request *, blk_status_t);
- 
-
-From 2c39a1d9ab4516d44e01e96f19f578b927e7f2e9 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Mon, 19 Dec 2016 18:11:33 +0100
-Subject: [PATCH 09/51] Copy header file bfq.h as bfq-mq.h
-
-This commit introduces the header file bfq-mq.h, that will play
-for bfq-mq-iosched.c the same role that bfq.h plays for bfq-iosched.c.
-
-For the moment, the file bfq-mq.h is just a copy of bfq.h.
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-mq-iosched.c |   2 +-
- block/bfq-mq.h         | 973 +++++++++++++++++++++++++++++++++++++++++++++++++
- 2 files changed, 974 insertions(+), 1 deletion(-)
- create mode 100644 block/bfq-mq.h
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index e88e00f1e0a7..d1125aee658c 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -83,7 +83,7 @@
- #include <linux/ioprio.h>
- #include "blk.h"
- #undef CONFIG_BFQ_GROUP_IOSCHED /* cgroups support not yet functional */
--#include "bfq.h"
-+#include "bfq-mq.h"
- 
- /* Expiration time of sync (0) and async (1) requests, in ns. */
- static const u64 bfq_fifo_expire[2] = { NSEC_PER_SEC / 4, NSEC_PER_SEC / 8 };
-diff --git a/block/bfq-mq.h b/block/bfq-mq.h
-new file mode 100644
-index 000000000000..53954d1b87f8
---- /dev/null
-+++ b/block/bfq-mq.h
-@@ -0,0 +1,973 @@
-+/*
-+ * BFQ v8r12 for 4.11.0: data structures and common functions prototypes.
-+ *
-+ * Based on ideas and code from CFQ:
-+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
-+ *
-+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
-+ *		      Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2017 Paolo Valente <paolo.valente@linaro.org>
-+ */
-+
-+#ifndef _BFQ_H
-+#define _BFQ_H
-+
-+#include <linux/blktrace_api.h>
-+#include <linux/hrtimer.h>
-+#include <linux/blk-cgroup.h>
-+
-+/*
-+ * Define an alternative macro to compile cgroups support. This is one
-+ * of the steps needed to let bfq-mq share the files bfq-sched.c and
-+ * bfq-cgroup.c with bfq-sq. For bfq-mq, the macro
-+ * BFQ_GROUP_IOSCHED_ENABLED will be defined as a function of whether
-+ * the configuration option CONFIG_BFQ_MQ_GROUP_IOSCHED, and not
-+ * CONFIG_BFQ_GROUP_IOSCHED, is defined.
-+ */
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#define BFQ_GROUP_IOSCHED_ENABLED
-+#endif
-+
-+#define BFQ_IOPRIO_CLASSES	3
-+#define BFQ_CL_IDLE_TIMEOUT	(HZ/5)
-+
-+#define BFQ_MIN_WEIGHT			1
-+#define BFQ_MAX_WEIGHT			1000
-+#define BFQ_WEIGHT_CONVERSION_COEFF	10
-+
-+#define BFQ_DEFAULT_QUEUE_IOPRIO	4
-+
-+#define BFQ_WEIGHT_LEGACY_DFL	100
-+#define BFQ_DEFAULT_GRP_IOPRIO	0
-+#define BFQ_DEFAULT_GRP_CLASS	IOPRIO_CLASS_BE
-+
-+/*
-+ * Soft real-time applications are extremely more latency sensitive
-+ * than interactive ones. Over-raise the weight of the former to
-+ * privilege them against the latter.
-+ */
-+#define BFQ_SOFTRT_WEIGHT_FACTOR	100
-+
-+struct bfq_entity;
-+
-+/**
-+ * struct bfq_service_tree - per ioprio_class service tree.
-+ *
-+ * Each service tree represents a B-WF2Q+ scheduler on its own.  Each
-+ * ioprio_class has its own independent scheduler, and so its own
-+ * bfq_service_tree.  All the fields are protected by the queue lock
-+ * of the containing bfqd.
-+ */
-+struct bfq_service_tree {
-+	/* tree for active entities (i.e., those backlogged) */
-+	struct rb_root active;
-+	/* tree for idle entities (i.e., not backlogged, with V <= F_i)*/
-+	struct rb_root idle;
-+
-+	struct bfq_entity *first_idle;	/* idle entity with minimum F_i */
-+	struct bfq_entity *last_idle;	/* idle entity with maximum F_i */
-+
-+	u64 vtime; /* scheduler virtual time */
-+	/* scheduler weight sum; active and idle entities contribute to it */
-+	unsigned long wsum;
-+};
-+
-+/**
-+ * struct bfq_sched_data - multi-class scheduler.
-+ *
-+ * bfq_sched_data is the basic scheduler queue.  It supports three
-+ * ioprio_classes, and can be used either as a toplevel queue or as an
-+ * intermediate queue in a hierarchical setup.
-+ *
-+ * The supported ioprio_classes are the same as in CFQ, in descending
-+ * priority order, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE.
-+ * Requests from higher priority queues are served before all the
-+ * requests from lower priority queues; among requests of the same
-+ * queue requests are served according to B-WF2Q+.
-+ *
-+ * The schedule is implemented by the service trees, plus the field
-+ * @next_in_service, which points to the entity on the active trees
-+ * that will be served next, if 1) no changes in the schedule occurs
-+ * before the current in-service entity is expired, 2) the in-service
-+ * queue becomes idle when it expires, and 3) if the entity pointed by
-+ * in_service_entity is not a queue, then the in-service child entity
-+ * of the entity pointed by in_service_entity becomes idle on
-+ * expiration. This peculiar definition allows for the following
-+ * optimization, not yet exploited: while a given entity is still in
-+ * service, we already know which is the best candidate for next
-+ * service among the other active entitities in the same parent
-+ * entity. We can then quickly compare the timestamps of the
-+ * in-service entity with those of such best candidate.
-+ *
-+ * All the fields are protected by the queue lock of the containing
-+ * bfqd.
-+ */
-+struct bfq_sched_data {
-+	struct bfq_entity *in_service_entity;  /* entity in service */
-+	/* head-of-the-line entity in the scheduler (see comments above) */
-+	struct bfq_entity *next_in_service;
-+	/* array of service trees, one per ioprio_class */
-+	struct bfq_service_tree service_tree[BFQ_IOPRIO_CLASSES];
-+	/* last time CLASS_IDLE was served */
-+	unsigned long bfq_class_idle_last_service;
-+
-+};
-+
-+/**
-+ * struct bfq_weight_counter - counter of the number of all active entities
-+ *                             with a given weight.
-+ */
-+struct bfq_weight_counter {
-+	unsigned int weight; /* weight of the entities this counter refers to */
-+	unsigned int num_active; /* nr of active entities with this weight */
-+	/*
-+	 * Weights tree member (see bfq_data's @queue_weights_tree and
-+	 * @group_weights_tree)
-+	 */
-+	struct rb_node weights_node;
-+};
-+
-+/**
-+ * struct bfq_entity - schedulable entity.
-+ *
-+ * A bfq_entity is used to represent either a bfq_queue (leaf node in the
-+ * cgroup hierarchy) or a bfq_group into the upper level scheduler.  Each
-+ * entity belongs to the sched_data of the parent group in the cgroup
-+ * hierarchy.  Non-leaf entities have also their own sched_data, stored
-+ * in @my_sched_data.
-+ *
-+ * Each entity stores independently its priority values; this would
-+ * allow different weights on different devices, but this
-+ * functionality is not exported to userspace by now.  Priorities and
-+ * weights are updated lazily, first storing the new values into the
-+ * new_* fields, then setting the @prio_changed flag.  As soon as
-+ * there is a transition in the entity state that allows the priority
-+ * update to take place the effective and the requested priority
-+ * values are synchronized.
-+ *
-+ * Unless cgroups are used, the weight value is calculated from the
-+ * ioprio to export the same interface as CFQ.  When dealing with
-+ * ``well-behaved'' queues (i.e., queues that do not spend too much
-+ * time to consume their budget and have true sequential behavior, and
-+ * when there are no external factors breaking anticipation) the
-+ * relative weights at each level of the cgroups hierarchy should be
-+ * guaranteed.  All the fields are protected by the queue lock of the
-+ * containing bfqd.
-+ */
-+struct bfq_entity {
-+	struct rb_node rb_node; /* service_tree member */
-+	/* pointer to the weight counter associated with this entity */
-+	struct bfq_weight_counter *weight_counter;
-+
-+	/*
-+	 * Flag, true if the entity is on a tree (either the active or
-+	 * the idle one of its service_tree) or is in service.
-+	 */
-+	bool on_st;
-+
-+	u64 finish; /* B-WF2Q+ finish timestamp (aka F_i) */
-+	u64 start;  /* B-WF2Q+ start timestamp (aka S_i) */
-+
-+	/* tree the entity is enqueued into; %NULL if not on a tree */
-+	struct rb_root *tree;
-+
-+	/*
-+	 * minimum start time of the (active) subtree rooted at this
-+	 * entity; used for O(log N) lookups into active trees
-+	 */
-+	u64 min_start;
-+
-+	/* amount of service received during the last service slot */
-+	int service;
-+
-+	/* budget, used also to calculate F_i: F_i = S_i + @budget / @weight */
-+	int budget;
-+
-+	unsigned int weight;	 /* weight of the queue */
-+	unsigned int new_weight; /* next weight if a change is in progress */
-+
-+	/* original weight, used to implement weight boosting */
-+	unsigned int orig_weight;
-+
-+	/* parent entity, for hierarchical scheduling */
-+	struct bfq_entity *parent;
-+
-+	/*
-+	 * For non-leaf nodes in the hierarchy, the associated
-+	 * scheduler queue, %NULL on leaf nodes.
-+	 */
-+	struct bfq_sched_data *my_sched_data;
-+	/* the scheduler queue this entity belongs to */
-+	struct bfq_sched_data *sched_data;
-+
-+	/* flag, set to request a weight, ioprio or ioprio_class change  */
-+	int prio_changed;
-+};
-+
-+struct bfq_group;
-+
-+/**
-+ * struct bfq_queue - leaf schedulable entity.
-+ *
-+ * A bfq_queue is a leaf request queue; it can be associated with an
-+ * io_context or more, if it  is  async or shared  between  cooperating
-+ * processes. @cgroup holds a reference to the cgroup, to be sure that it
-+ * does not disappear while a bfqq still references it (mostly to avoid
-+ * races between request issuing and task migration followed by cgroup
-+ * destruction).
-+ * All the fields are protected by the queue lock of the containing bfqd.
-+ */
-+struct bfq_queue {
-+	/* reference counter */
-+	int ref;
-+	/* parent bfq_data */
-+	struct bfq_data *bfqd;
-+
-+	/* current ioprio and ioprio class */
-+	unsigned short ioprio, ioprio_class;
-+	/* next ioprio and ioprio class if a change is in progress */
-+	unsigned short new_ioprio, new_ioprio_class;
-+
-+	/*
-+	 * Shared bfq_queue if queue is cooperating with one or more
-+	 * other queues.
-+	 */
-+	struct bfq_queue *new_bfqq;
-+	/* request-position tree member (see bfq_group's @rq_pos_tree) */
-+	struct rb_node pos_node;
-+	/* request-position tree root (see bfq_group's @rq_pos_tree) */
-+	struct rb_root *pos_root;
-+
-+	/* sorted list of pending requests */
-+	struct rb_root sort_list;
-+	/* if fifo isn't expired, next request to serve */
-+	struct request *next_rq;
-+	/* number of sync and async requests queued */
-+	int queued[2];
-+	/* number of sync and async requests currently allocated */
-+	int allocated[2];
-+	/* number of pending metadata requests */
-+	int meta_pending;
-+	/* fifo list of requests in sort_list */
-+	struct list_head fifo;
-+
-+	/* entity representing this queue in the scheduler */
-+	struct bfq_entity entity;
-+
-+	/* maximum budget allowed from the feedback mechanism */
-+	int max_budget;
-+	/* budget expiration (in jiffies) */
-+	unsigned long budget_timeout;
-+
-+	/* number of requests on the dispatch list or inside driver */
-+	int dispatched;
-+
-+	unsigned int flags; /* status flags.*/
-+
-+	/* node for active/idle bfqq list inside parent bfqd */
-+	struct list_head bfqq_list;
-+
-+	/* bit vector: a 1 for each seeky requests in history */
-+	u32 seek_history;
-+
-+	/* node for the device's burst list */
-+	struct hlist_node burst_list_node;
-+
-+	/* position of the last request enqueued */
-+	sector_t last_request_pos;
-+
-+	/* Number of consecutive pairs of request completion and
-+	 * arrival, such that the queue becomes idle after the
-+	 * completion, but the next request arrives within an idle
-+	 * time slice; used only if the queue's IO_bound flag has been
-+	 * cleared.
-+	 */
-+	unsigned int requests_within_timer;
-+
-+	/* pid of the process owning the queue, used for logging purposes */
-+	pid_t pid;
-+
-+	/*
-+	 * Pointer to the bfq_io_cq owning the bfq_queue, set to %NULL
-+	 * if the queue is shared.
-+	 */
-+	struct bfq_io_cq *bic;
-+
-+	/* current maximum weight-raising time for this queue */
-+	unsigned long wr_cur_max_time;
-+	/*
-+	 * Minimum time instant such that, only if a new request is
-+	 * enqueued after this time instant in an idle @bfq_queue with
-+	 * no outstanding requests, then the task associated with the
-+	 * queue it is deemed as soft real-time (see the comments on
-+	 * the function bfq_bfqq_softrt_next_start())
-+	 */
-+	unsigned long soft_rt_next_start;
-+	/*
-+	 * Start time of the current weight-raising period if
-+	 * the @bfq-queue is being weight-raised, otherwise
-+	 * finish time of the last weight-raising period.
-+	 */
-+	unsigned long last_wr_start_finish;
-+	/* factor by which the weight of this queue is multiplied */
-+	unsigned int wr_coeff;
-+	/*
-+	 * Time of the last transition of the @bfq_queue from idle to
-+	 * backlogged.
-+	 */
-+	unsigned long last_idle_bklogged;
-+	/*
-+	 * Cumulative service received from the @bfq_queue since the
-+	 * last transition from idle to backlogged.
-+	 */
-+	unsigned long service_from_backlogged;
-+	/*
-+	 * Value of wr start time when switching to soft rt
-+	 */
-+	unsigned long wr_start_at_switch_to_srt;
-+
-+	unsigned long split_time; /* time of last split */
-+};
-+
-+/**
-+ * struct bfq_ttime - per process thinktime stats.
-+ */
-+struct bfq_ttime {
-+	u64 last_end_request; /* completion time of last request */
-+
-+	u64 ttime_total; /* total process thinktime */
-+	unsigned long ttime_samples; /* number of thinktime samples */
-+	u64 ttime_mean; /* average process thinktime */
-+
-+};
-+
-+/**
-+ * struct bfq_io_cq - per (request_queue, io_context) structure.
-+ */
-+struct bfq_io_cq {
-+	/* associated io_cq structure */
-+	struct io_cq icq; /* must be the first member */
-+	/* array of two process queues, the sync and the async */
-+	struct bfq_queue *bfqq[2];
-+	/* associated @bfq_ttime struct */
-+	struct bfq_ttime ttime;
-+	/* per (request_queue, blkcg) ioprio */
-+	int ioprio;
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	uint64_t blkcg_serial_nr; /* the current blkcg serial */
-+#endif
-+
-+	/*
-+	 * Snapshot of the has_short_time flag before merging; taken
-+	 * to remember its value while the queue is merged, so as to
-+	 * be able to restore it in case of split.
-+	 */
-+	bool saved_has_short_ttime;
-+	/*
-+	 * Same purpose as the previous two fields for the I/O bound
-+	 * classification of a queue.
-+	 */
-+	bool saved_IO_bound;
-+
-+	/*
-+	 * Same purpose as the previous fields for the value of the
-+	 * field keeping the queue's belonging to a large burst
-+	 */
-+	bool saved_in_large_burst;
-+	/*
-+	 * True if the queue belonged to a burst list before its merge
-+	 * with another cooperating queue.
-+	 */
-+	bool was_in_burst_list;
-+
-+	/*
-+	 * Similar to previous fields: save wr information.
-+	 */
-+	unsigned long saved_wr_coeff;
-+	unsigned long saved_last_wr_start_finish;
-+	unsigned long saved_wr_start_at_switch_to_srt;
-+	unsigned int saved_wr_cur_max_time;
-+};
-+
-+enum bfq_device_speed {
-+	BFQ_BFQD_FAST,
-+	BFQ_BFQD_SLOW,
-+};
-+
-+/**
-+ * struct bfq_data - per-device data structure.
-+ *
-+ * All the fields are protected by the @queue lock.
-+ */
-+struct bfq_data {
-+	/* request queue for the device */
-+	struct request_queue *queue;
-+
-+	/* root bfq_group for the device */
-+	struct bfq_group *root_group;
-+
-+	/*
-+	 * rbtree of weight counters of @bfq_queues, sorted by
-+	 * weight. Used to keep track of whether all @bfq_queues have
-+	 * the same weight. The tree contains one counter for each
-+	 * distinct weight associated to some active and not
-+	 * weight-raised @bfq_queue (see the comments to the functions
-+	 * bfq_weights_tree_[add|remove] for further details).
-+	 */
-+	struct rb_root queue_weights_tree;
-+	/*
-+	 * rbtree of non-queue @bfq_entity weight counters, sorted by
-+	 * weight. Used to keep track of whether all @bfq_groups have
-+	 * the same weight. The tree contains one counter for each
-+	 * distinct weight associated to some active @bfq_group (see
-+	 * the comments to the functions bfq_weights_tree_[add|remove]
-+	 * for further details).
-+	 */
-+	struct rb_root group_weights_tree;
-+
-+	/*
-+	 * Number of bfq_queues containing requests (including the
-+	 * queue in service, even if it is idling).
-+	 */
-+	int busy_queues;
-+	/* number of weight-raised busy @bfq_queues */
-+	int wr_busy_queues;
-+	/* number of queued requests */
-+	int queued;
-+	/* number of requests dispatched and waiting for completion */
-+	int rq_in_driver;
-+
-+	/*
-+	 * Maximum number of requests in driver in the last
-+	 * @hw_tag_samples completed requests.
-+	 */
-+	int max_rq_in_driver;
-+	/* number of samples used to calculate hw_tag */
-+	int hw_tag_samples;
-+	/* flag set to one if the driver is showing a queueing behavior */
-+	int hw_tag;
-+
-+	/* number of budgets assigned */
-+	int budgets_assigned;
-+
-+	/*
-+	 * Timer set when idling (waiting) for the next request from
-+	 * the queue in service.
-+	 */
-+	struct hrtimer idle_slice_timer;
-+	/* delayed work to restart dispatching on the request queue */
-+	struct work_struct unplug_work;
-+
-+	/* bfq_queue in service */
-+	struct bfq_queue *in_service_queue;
-+	/* bfq_io_cq (bic) associated with the @in_service_queue */
-+	struct bfq_io_cq *in_service_bic;
-+
-+	/* on-disk position of the last served request */
-+	sector_t last_position;
-+
-+	/* time of last request completion (ns) */
-+	u64 last_completion;
-+
-+	/* time of first rq dispatch in current observation interval (ns) */
-+	u64 first_dispatch;
-+	/* time of last rq dispatch in current observation interval (ns) */
-+	u64 last_dispatch;
-+
-+	/* beginning of the last budget */
-+	ktime_t last_budget_start;
-+	/* beginning of the last idle slice */
-+	ktime_t last_idling_start;
-+
-+	/* number of samples in current observation interval */
-+	int peak_rate_samples;
-+	/* num of samples of seq dispatches in current observation interval */
-+	u32 sequential_samples;
-+	/* total num of sectors transferred in current observation interval */
-+	u64 tot_sectors_dispatched;
-+	/* max rq size seen during current observation interval (sectors) */
-+	u32 last_rq_max_size;
-+	/* time elapsed from first dispatch in current observ. interval (us) */
-+	u64 delta_from_first;
-+	/* current estimate of device peak rate */
-+	u32 peak_rate;
-+
-+	/* maximum budget allotted to a bfq_queue before rescheduling */
-+	int bfq_max_budget;
-+
-+	/* list of all the bfq_queues active on the device */
-+	struct list_head active_list;
-+	/* list of all the bfq_queues idle on the device */
-+	struct list_head idle_list;
-+
-+	/*
-+	 * Timeout for async/sync requests; when it fires, requests
-+	 * are served in fifo order.
-+	 */
-+	u64 bfq_fifo_expire[2];
-+	/* weight of backward seeks wrt forward ones */
-+	unsigned int bfq_back_penalty;
-+	/* maximum allowed backward seek */
-+	unsigned int bfq_back_max;
-+	/* maximum idling time */
-+	u32 bfq_slice_idle;
-+
-+	/* user-configured max budget value (0 for auto-tuning) */
-+	int bfq_user_max_budget;
-+	/*
-+	 * Timeout for bfq_queues to consume their budget; used to
-+	 * prevent seeky queues from imposing long latencies to
-+	 * sequential or quasi-sequential ones (this also implies that
-+	 * seeky queues cannot receive guarantees in the service
-+	 * domain; after a timeout they are charged for the time they
-+	 * have been in service, to preserve fairness among them, but
-+	 * without service-domain guarantees).
-+	 */
-+	unsigned int bfq_timeout;
-+
-+	/*
-+	 * Number of consecutive requests that must be issued within
-+	 * the idle time slice to set again idling to a queue which
-+	 * was marked as non-I/O-bound (see the definition of the
-+	 * IO_bound flag for further details).
-+	 */
-+	unsigned int bfq_requests_within_timer;
-+
-+	/*
-+	 * Force device idling whenever needed to provide accurate
-+	 * service guarantees, without caring about throughput
-+	 * issues. CAVEAT: this may even increase latencies, in case
-+	 * of useless idling for processes that did stop doing I/O.
-+	 */
-+	bool strict_guarantees;
-+
-+	/*
-+	 * Last time at which a queue entered the current burst of
-+	 * queues being activated shortly after each other; for more
-+	 * details about this and the following parameters related to
-+	 * a burst of activations, see the comments on the function
-+	 * bfq_handle_burst.
-+	 */
-+	unsigned long last_ins_in_burst;
-+	/*
-+	 * Reference time interval used to decide whether a queue has
-+	 * been activated shortly after @last_ins_in_burst.
-+	 */
-+	unsigned long bfq_burst_interval;
-+	/* number of queues in the current burst of queue activations */
-+	int burst_size;
-+
-+	/* common parent entity for the queues in the burst */
-+	struct bfq_entity *burst_parent_entity;
-+	/* Maximum burst size above which the current queue-activation
-+	 * burst is deemed as 'large'.
-+	 */
-+	unsigned long bfq_large_burst_thresh;
-+	/* true if a large queue-activation burst is in progress */
-+	bool large_burst;
-+	/*
-+	 * Head of the burst list (as for the above fields, more
-+	 * details in the comments on the function bfq_handle_burst).
-+	 */
-+	struct hlist_head burst_list;
-+
-+	/* if set to true, low-latency heuristics are enabled */
-+	bool low_latency;
-+	/*
-+	 * Maximum factor by which the weight of a weight-raised queue
-+	 * is multiplied.
-+	 */
-+	unsigned int bfq_wr_coeff;
-+	/* maximum duration of a weight-raising period (jiffies) */
-+	unsigned int bfq_wr_max_time;
-+
-+	/* Maximum weight-raising duration for soft real-time processes */
-+	unsigned int bfq_wr_rt_max_time;
-+	/*
-+	 * Minimum idle period after which weight-raising may be
-+	 * reactivated for a queue (in jiffies).
-+	 */
-+	unsigned int bfq_wr_min_idle_time;
-+	/*
-+	 * Minimum period between request arrivals after which
-+	 * weight-raising may be reactivated for an already busy async
-+	 * queue (in jiffies).
-+	 */
-+	unsigned long bfq_wr_min_inter_arr_async;
-+
-+	/* Max service-rate for a soft real-time queue, in sectors/sec */
-+	unsigned int bfq_wr_max_softrt_rate;
-+	/*
-+	 * Cached value of the product R*T, used for computing the
-+	 * maximum duration of weight raising automatically.
-+	 */
-+	u64 RT_prod;
-+	/* device-speed class for the low-latency heuristic */
-+	enum bfq_device_speed device_speed;
-+
-+	/* fallback dummy bfqq for extreme OOM conditions */
-+	struct bfq_queue oom_bfqq;
-+};
-+
-+enum bfqq_state_flags {
-+	BFQ_BFQQ_FLAG_just_created = 0,	/* queue just allocated */
-+	BFQ_BFQQ_FLAG_busy,		/* has requests or is in service */
-+	BFQ_BFQQ_FLAG_wait_request,	/* waiting for a request */
-+	BFQ_BFQQ_FLAG_non_blocking_wait_rq, /*
-+					     * waiting for a request
-+					     * without idling the device
-+					     */
-+	BFQ_BFQQ_FLAG_must_alloc,	/* must be allowed rq alloc */
-+	BFQ_BFQQ_FLAG_fifo_expire,	/* FIFO checked in this slice */
-+	BFQ_BFQQ_FLAG_has_short_ttime,	/* queue has a short think time */
-+	BFQ_BFQQ_FLAG_sync,		/* synchronous queue */
-+	BFQ_BFQQ_FLAG_IO_bound,		/*
-+					 * bfqq has timed-out at least once
-+					 * having consumed at most 2/10 of
-+					 * its budget
-+					 */
-+	BFQ_BFQQ_FLAG_in_large_burst,	/*
-+					 * bfqq activated in a large burst,
-+					 * see comments to bfq_handle_burst.
-+					 */
-+	BFQ_BFQQ_FLAG_softrt_update,	/*
-+					 * may need softrt-next-start
-+					 * update
-+					 */
-+	BFQ_BFQQ_FLAG_coop,		/* bfqq is shared */
-+	BFQ_BFQQ_FLAG_split_coop	/* shared bfqq will be split */
-+};
-+
-+#define BFQ_BFQQ_FNS(name)						\
-+static void bfq_mark_bfqq_##name(struct bfq_queue *bfqq)		\
-+{									\
-+	(bfqq)->flags |= (1 << BFQ_BFQQ_FLAG_##name);			\
-+}									\
-+static void bfq_clear_bfqq_##name(struct bfq_queue *bfqq)		\
-+{									\
-+	(bfqq)->flags &= ~(1 << BFQ_BFQQ_FLAG_##name);			\
-+}									\
-+static int bfq_bfqq_##name(const struct bfq_queue *bfqq)		\
-+{									\
-+	return ((bfqq)->flags & (1 << BFQ_BFQQ_FLAG_##name)) != 0;	\
-+}
-+
-+BFQ_BFQQ_FNS(just_created);
-+BFQ_BFQQ_FNS(busy);
-+BFQ_BFQQ_FNS(wait_request);
-+BFQ_BFQQ_FNS(non_blocking_wait_rq);
-+BFQ_BFQQ_FNS(must_alloc);
-+BFQ_BFQQ_FNS(fifo_expire);
-+BFQ_BFQQ_FNS(has_short_ttime);
-+BFQ_BFQQ_FNS(sync);
-+BFQ_BFQQ_FNS(IO_bound);
-+BFQ_BFQQ_FNS(in_large_burst);
-+BFQ_BFQQ_FNS(coop);
-+BFQ_BFQQ_FNS(split_coop);
-+BFQ_BFQQ_FNS(softrt_update);
-+#undef BFQ_BFQQ_FNS
-+
-+/* Logging facilities. */
-+#ifdef CONFIG_BFQ_REDIRECT_TO_CONSOLE
-+
-+static const char *checked_dev_name(const struct device *dev)
-+{
-+	static const char nodev[] = "nodev";
-+
-+	if (dev)
-+		return dev_name(dev);
-+
-+	return nodev;
-+}
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+static struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
-+static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
-+
-+#define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	do {			\
-+	char __pbuf[128];						\
-+									\
-+	assert_spin_locked((bfqd)->queue->queue_lock);			\
-+	blkg_path(bfqg_to_blkg(bfqq_group(bfqq)), __pbuf, sizeof(__pbuf)); \
-+	pr_crit("%s bfq%d%c %s " fmt "\n", 				\
-+		checked_dev_name((bfqd)->queue->backing_dev_info->dev),	\
-+		(bfqq)->pid,						\
-+		bfq_bfqq_sync((bfqq)) ? 'S' : 'A',			\
-+		__pbuf, ##args);					\
-+} while (0)
-+
-+#define bfq_log_bfqg(bfqd, bfqg, fmt, args...)	do {			\
-+	char __pbuf[128];						\
-+									\
-+	blkg_path(bfqg_to_blkg(bfqg), __pbuf, sizeof(__pbuf));		\
-+	pr_crit("%s %s " fmt "\n",					\
-+	checked_dev_name((bfqd)->queue->backing_dev_info->dev),		\
-+	__pbuf, ##args);						\
-+} while (0)
-+
-+#else /* BFQ_GROUP_IOSCHED_ENABLED */
-+
-+#define bfq_log_bfqq(bfqd, bfqq, fmt, args...)				\
-+	pr_crit("%s bfq%d%c " fmt "\n",					\
-+		checked_dev_name((bfqd)->queue->backing_dev_info->dev),	\
-+		(bfqq)->pid, bfq_bfqq_sync((bfqq)) ? 'S' : 'A',		\
-+		##args)
-+#define bfq_log_bfqg(bfqd, bfqg, fmt, args...)		do {} while (0)
-+
-+#endif /* BFQ_GROUP_IOSCHED_ENABLED */
-+
-+#define bfq_log(bfqd, fmt, args...) \
-+	pr_crit("%s bfq " fmt "\n",					\
-+		checked_dev_name((bfqd)->queue->backing_dev_info->dev),	\
-+		##args)
-+
-+#else /* CONFIG_BFQ_REDIRECT_TO_CONSOLE */
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+static struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
-+static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
-+
-+#define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	do {			\
-+	char __pbuf[128];						\
-+									\
-+	assert_spin_locked((bfqd)->queue->queue_lock);			\
-+	blkg_path(bfqg_to_blkg(bfqq_group(bfqq)), __pbuf, sizeof(__pbuf)); \
-+	blk_add_trace_msg((bfqd)->queue, "bfq%d%c %s " fmt, \
-+			  (bfqq)->pid,			  \
-+			  bfq_bfqq_sync((bfqq)) ? 'S' : 'A',	\
-+			  __pbuf, ##args);				\
-+} while (0)
-+
-+#define bfq_log_bfqg(bfqd, bfqg, fmt, args...)	do {			\
-+	char __pbuf[128];						\
-+									\
-+	blkg_path(bfqg_to_blkg(bfqg), __pbuf, sizeof(__pbuf));		\
-+	blk_add_trace_msg((bfqd)->queue, "%s " fmt, __pbuf, ##args);	\
-+} while (0)
-+
-+#else /* BFQ_GROUP_IOSCHED_ENABLED */
-+
-+#define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	\
-+	blk_add_trace_msg((bfqd)->queue, "bfq%d%c " fmt, (bfqq)->pid,	\
-+			bfq_bfqq_sync((bfqq)) ? 'S' : 'A',		\
-+				##args)
-+#define bfq_log_bfqg(bfqd, bfqg, fmt, args...)		do {} while (0)
-+
-+#endif /* BFQ_GROUP_IOSCHED_ENABLED */
-+
-+#define bfq_log(bfqd, fmt, args...) \
-+	blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args)
-+#endif /* CONFIG_BFQ_REDIRECT_TO_CONSOLE */
-+
-+/* Expiration reasons. */
-+enum bfqq_expiration {
-+	BFQ_BFQQ_TOO_IDLE = 0,		/*
-+					 * queue has been idling for
-+					 * too long
-+					 */
-+	BFQ_BFQQ_BUDGET_TIMEOUT,	/* budget took too long to be used */
-+	BFQ_BFQQ_BUDGET_EXHAUSTED,	/* budget consumed */
-+	BFQ_BFQQ_NO_MORE_REQUESTS,	/* the queue has no more requests */
-+	BFQ_BFQQ_PREEMPTED		/* preemption in progress */
-+};
-+
-+
-+struct bfqg_stats {
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	/* number of ios merged */
-+	struct blkg_rwstat		merged;
-+	/* total time spent on device in ns, may not be accurate w/ queueing */
-+	struct blkg_rwstat		service_time;
-+	/* total time spent waiting in scheduler queue in ns */
-+	struct blkg_rwstat		wait_time;
-+	/* number of IOs queued up */
-+	struct blkg_rwstat		queued;
-+	/* total disk time and nr sectors dispatched by this group */
-+	struct blkg_stat		time;
-+	/* sum of number of ios queued across all samples */
-+	struct blkg_stat		avg_queue_size_sum;
-+	/* count of samples taken for average */
-+	struct blkg_stat		avg_queue_size_samples;
-+	/* how many times this group has been removed from service tree */
-+	struct blkg_stat		dequeue;
-+	/* total time spent waiting for it to be assigned a timeslice. */
-+	struct blkg_stat		group_wait_time;
-+	/* time spent idling for this blkcg_gq */
-+	struct blkg_stat		idle_time;
-+	/* total time with empty current active q with other requests queued */
-+	struct blkg_stat		empty_time;
-+	/* fields after this shouldn't be cleared on stat reset */
-+	uint64_t			start_group_wait_time;
-+	uint64_t			start_idle_time;
-+	uint64_t			start_empty_time;
-+	uint16_t			flags;
-+#endif
-+};
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+/*
-+ * struct bfq_group_data - per-blkcg storage for the blkio subsystem.
-+ *
-+ * @ps: @blkcg_policy_storage that this structure inherits
-+ * @weight: weight of the bfq_group
-+ */
-+struct bfq_group_data {
-+	/* must be the first member */
-+	struct blkcg_policy_data pd;
-+
-+	unsigned int weight;
-+};
-+
-+/**
-+ * struct bfq_group - per (device, cgroup) data structure.
-+ * @entity: schedulable entity to insert into the parent group sched_data.
-+ * @sched_data: own sched_data, to contain child entities (they may be
-+ *              both bfq_queues and bfq_groups).
-+ * @bfqd: the bfq_data for the device this group acts upon.
-+ * @async_bfqq: array of async queues for all the tasks belonging to
-+ *              the group, one queue per ioprio value per ioprio_class,
-+ *              except for the idle class that has only one queue.
-+ * @async_idle_bfqq: async queue for the idle class (ioprio is ignored).
-+ * @my_entity: pointer to @entity, %NULL for the toplevel group; used
-+ *             to avoid too many special cases during group creation/
-+ *             migration.
-+ * @active_entities: number of active entities belonging to the group;
-+ *                   unused for the root group. Used to know whether there
-+ *                   are groups with more than one active @bfq_entity
-+ *                   (see the comments to the function
-+ *                   bfq_bfqq_may_idle()).
-+ * @rq_pos_tree: rbtree sorted by next_request position, used when
-+ *               determining if two or more queues have interleaving
-+ *               requests (see bfq_find_close_cooperator()).
-+ *
-+ * Each (device, cgroup) pair has its own bfq_group, i.e., for each cgroup
-+ * there is a set of bfq_groups, each one collecting the lower-level
-+ * entities belonging to the group that are acting on the same device.
-+ *
-+ * Locking works as follows:
-+ *    o @bfqd is protected by the queue lock, RCU is used to access it
-+ *      from the readers.
-+ *    o All the other fields are protected by the @bfqd queue lock.
-+ */
-+struct bfq_group {
-+	/* must be the first member */
-+	struct blkg_policy_data pd;
-+
-+	struct bfq_entity entity;
-+	struct bfq_sched_data sched_data;
-+
-+	void *bfqd;
-+
-+	struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
-+	struct bfq_queue *async_idle_bfqq;
-+
-+	struct bfq_entity *my_entity;
-+
-+	int active_entities;
-+
-+	struct rb_root rq_pos_tree;
-+
-+	struct bfqg_stats stats;
-+};
-+
-+#else
-+struct bfq_group {
-+	struct bfq_sched_data sched_data;
-+
-+	struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
-+	struct bfq_queue *async_idle_bfqq;
-+
-+	struct rb_root rq_pos_tree;
-+};
-+#endif
-+
-+static struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity);
-+
-+static unsigned int bfq_class_idx(struct bfq_entity *entity)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+
-+	return bfqq ? bfqq->ioprio_class - 1 :
-+		BFQ_DEFAULT_GRP_CLASS - 1;
-+}
-+
-+static struct bfq_service_tree *
-+bfq_entity_service_tree(struct bfq_entity *entity)
-+{
-+	struct bfq_sched_data *sched_data = entity->sched_data;
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+	unsigned int idx = bfq_class_idx(entity);
-+
-+	BUG_ON(idx >= BFQ_IOPRIO_CLASSES);
-+	BUG_ON(sched_data == NULL);
-+
-+	if (bfqq)
-+		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			     "entity_service_tree %p %d",
-+			     sched_data->service_tree + idx, idx);
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	else {
-+		struct bfq_group *bfqg =
-+			container_of(entity, struct bfq_group, entity);
-+
-+		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+			     "entity_service_tree %p %d",
-+			     sched_data->service_tree + idx, idx);
-+	}
-+#endif
-+	return sched_data->service_tree + idx;
-+}
-+
-+static struct bfq_queue *bic_to_bfqq(struct bfq_io_cq *bic, bool is_sync)
-+{
-+	return bic->bfqq[is_sync];
-+}
-+
-+static void bic_set_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq,
-+			 bool is_sync)
-+{
-+	bic->bfqq[is_sync] = bfqq;
-+}
-+
-+static struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic)
-+{
-+	return bic->icq.q->elevator->elevator_data;
-+}
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+
-+static struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq)
-+{
-+	struct bfq_entity *group_entity = bfqq->entity.parent;
-+
-+	if (!group_entity)
-+		group_entity = &bfqq->bfqd->root_group->entity;
-+
-+	return container_of(group_entity, struct bfq_group, entity);
-+}
-+
-+#else
-+
-+static struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq)
-+{
-+	return bfqq->bfqd->root_group;
-+}
-+
-+#endif
-+
-+static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio);
-+static void bfq_put_queue(struct bfq_queue *bfqq);
-+static void bfq_dispatch_insert(struct request_queue *q, struct request *rq);
-+static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd,
-+				       struct bio *bio, bool is_sync,
-+				       struct bfq_io_cq *bic);
-+static void bfq_end_wr_async_queues(struct bfq_data *bfqd,
-+				    struct bfq_group *bfqg);
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);
-+#endif
-+static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq);
-+
-+#endif /* _BFQ_H */
-
-From 0bd96428e086fd28800efdf5f0a5f62869af6e30 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Sat, 21 Jan 2017 12:41:14 +0100
-Subject: [PATCH 10/51] Move thinktime from bic to bfqq
-
-Prep change to make it possible to protect this field with a
-scheduler lock.
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-mq-iosched.c | 28 ++++++++++++++--------------
- block/bfq-mq.h         | 30 ++++++++++++++++--------------
- 2 files changed, 30 insertions(+), 28 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index d1125aee658c..65f5dfb79417 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -698,6 +698,7 @@ bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_data *bfqd,
- 	if (unlikely(busy))
- 		old_wr_coeff = bfqq->wr_coeff;
- 
-+	bfqq->ttime = bic->saved_ttime;
- 	bfqq->wr_coeff = bic->saved_wr_coeff;
- 	bfqq->wr_start_at_switch_to_srt = bic->saved_wr_start_at_switch_to_srt;
- 	BUG_ON(time_is_after_jiffies(bfqq->wr_start_at_switch_to_srt));
-@@ -1287,7 +1288,7 @@ static void bfq_bfqq_handle_idle_busy_switch(struct bfq_data *bfqd,
- 		 * details on the usage of the next variable.
- 		 */
- 		arrived_in_time =  ktime_get_ns() <=
--			RQ_BIC(rq)->ttime.last_end_request +
-+			bfqq->ttime.last_end_request +
- 			bfqd->bfq_slice_idle * 3;
- 
- 	bfq_log_bfqq(bfqd, bfqq,
-@@ -2048,6 +2049,7 @@ static void bfq_bfqq_save_state(struct bfq_queue *bfqq)
- 	if (!bic)
- 		return;
- 
-+	bic->saved_ttime = bfqq->ttime;
- 	bic->saved_has_short_ttime = bfq_bfqq_has_short_ttime(bfqq);
- 	bic->saved_IO_bound = bfq_bfqq_IO_bound(bfqq);
- 	bic->saved_in_large_burst = bfq_bfqq_in_large_burst(bfqq);
-@@ -3948,11 +3950,6 @@ static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
- 	bfq_put_queue(bfqq); /* release process reference */
- }
- 
--static void bfq_init_icq(struct io_cq *icq)
--{
--	icq_to_bic(icq)->ttime.last_end_request = ktime_get_ns() - (1ULL<<32);
--}
--
- static void bfq_exit_icq(struct io_cq *icq)
- {
- 	struct bfq_io_cq *bic = icq_to_bic(icq);
-@@ -4084,6 +4081,9 @@ static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 		bfq_mark_bfqq_just_created(bfqq);
- 	} else
- 		bfq_clear_bfqq_sync(bfqq);
-+
-+	bfqq->ttime.last_end_request = ktime_get_ns() - (1ULL<<32);
-+
- 	bfq_mark_bfqq_IO_bound(bfqq);
- 
- 	/* Tentative initial value to trade off between thr and lat */
-@@ -4191,14 +4191,14 @@ static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd,
- }
- 
- static void bfq_update_io_thinktime(struct bfq_data *bfqd,
--				    struct bfq_io_cq *bic)
-+				    struct bfq_queue *bfqq)
- {
--	struct bfq_ttime *ttime = &bic->ttime;
--	u64 elapsed = ktime_get_ns() - bic->ttime.last_end_request;
-+	struct bfq_ttime *ttime = &bfqq->ttime;
-+	u64 elapsed = ktime_get_ns() - bfqq->ttime.last_end_request;
- 
- 	elapsed = min_t(u64, elapsed, 2 * bfqd->bfq_slice_idle);
- 
--	ttime->ttime_samples = (7*bic->ttime.ttime_samples + 256) / 8;
-+	ttime->ttime_samples = (7*bfqq->ttime.ttime_samples + 256) / 8;
- 	ttime->ttime_total = div_u64(7*ttime->ttime_total + 256*elapsed,  8);
- 	ttime->ttime_mean = div64_ul(ttime->ttime_total + 128,
- 				     ttime->ttime_samples);
-@@ -4240,8 +4240,8 @@ static void bfq_update_has_short_ttime(struct bfq_data *bfqd,
- 	 * decide whether to mark as has_short_ttime
- 	 */
- 	if (atomic_read(&bic->icq.ioc->active_ref) == 0 ||
--	    (bfq_sample_valid(bic->ttime.ttime_samples) &&
--	     bic->ttime.ttime_mean > bfqd->bfq_slice_idle))
-+	    (bfq_sample_valid(bfqq->ttime.ttime_samples) &&
-+	     bfqq->ttime.ttime_mean > bfqd->bfq_slice_idle))
- 		has_short_ttime = false;
- 
- 	bfq_log_bfqq(bfqd, bfqq, "update_has_short_ttime: has_short_ttime %d",
-@@ -4265,7 +4265,7 @@ static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 	if (rq->cmd_flags & REQ_META)
- 		bfqq->meta_pending++;
- 
--	bfq_update_io_thinktime(bfqd, bic);
-+	bfq_update_io_thinktime(bfqd, bfqq);
- 	bfq_update_has_short_ttime(bfqd, bfqq, bic);
- 	bfq_update_io_seektime(bfqd, bfqq, rq);
- 
-@@ -4436,7 +4436,7 @@ static void bfq_completed_request(struct request_queue *q, struct request *rq)
- 
- 	now_ns = ktime_get_ns();
- 
--	RQ_BIC(rq)->ttime.last_end_request = now_ns;
-+	bfqq->ttime.last_end_request = now_ns;
- 
- 	/*
- 	 * Using us instead of ns, to get a reasonable precision in
-diff --git a/block/bfq-mq.h b/block/bfq-mq.h
-index 53954d1b87f8..0f51f270469c 100644
---- a/block/bfq-mq.h
-+++ b/block/bfq-mq.h
-@@ -210,6 +210,18 @@ struct bfq_entity {
- struct bfq_group;
- 
- /**
-+ * struct bfq_ttime - per process thinktime stats.
-+ */
-+struct bfq_ttime {
-+	u64 last_end_request; /* completion time of last request */
-+
-+	u64 ttime_total; /* total process thinktime */
-+	unsigned long ttime_samples; /* number of thinktime samples */
-+	u64 ttime_mean; /* average process thinktime */
-+
-+};
-+
-+/**
-  * struct bfq_queue - leaf schedulable entity.
-  *
-  * A bfq_queue is a leaf request queue; it can be associated with an
-@@ -270,6 +282,9 @@ struct bfq_queue {
- 	/* node for active/idle bfqq list inside parent bfqd */
- 	struct list_head bfqq_list;
- 
-+	/* associated @bfq_ttime struct */
-+	struct bfq_ttime ttime;
-+
- 	/* bit vector: a 1 for each seeky requests in history */
- 	u32 seek_history;
- 
-@@ -333,18 +348,6 @@ struct bfq_queue {
- };
- 
- /**
-- * struct bfq_ttime - per process thinktime stats.
-- */
--struct bfq_ttime {
--	u64 last_end_request; /* completion time of last request */
--
--	u64 ttime_total; /* total process thinktime */
--	unsigned long ttime_samples; /* number of thinktime samples */
--	u64 ttime_mean; /* average process thinktime */
--
--};
--
--/**
-  * struct bfq_io_cq - per (request_queue, io_context) structure.
-  */
- struct bfq_io_cq {
-@@ -352,8 +355,6 @@ struct bfq_io_cq {
- 	struct io_cq icq; /* must be the first member */
- 	/* array of two process queues, the sync and the async */
- 	struct bfq_queue *bfqq[2];
--	/* associated @bfq_ttime struct */
--	struct bfq_ttime ttime;
- 	/* per (request_queue, blkcg) ioprio */
- 	int ioprio;
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
-@@ -390,6 +391,7 @@ struct bfq_io_cq {
- 	unsigned long saved_last_wr_start_finish;
- 	unsigned long saved_wr_start_at_switch_to_srt;
- 	unsigned int saved_wr_cur_max_time;
-+	struct bfq_ttime saved_ttime;
- };
- 
- enum bfq_device_speed {
-
-From 351a9aea7c0c9c30edacdbf2a3c0d089470de1e8 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Wed, 18 Jan 2017 11:42:22 +0100
-Subject: [PATCH 11/51] Embed bfq-ioc.c and add locking on request queue
-
-The version of bfq-ioc.c for bfq-iosched.c is not correct any more for
-bfq-mq, because, in bfq-mq, the request queue lock is not being held
-when bfq_bic_lookup is invoked. That function must then take that look
-on its own. This commit removes the inclusion of bfq-ioc.c, copies the
-content of bfq-ioc.c into bfq-mq-iosched.c, and adds the grabbing of
-the lock.
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-mq-iosched.c | 39 ++++++++++++++++++++++++++++++++++++---
- 1 file changed, 36 insertions(+), 3 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 65f5dfb79417..756a618d5902 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -195,7 +195,39 @@ static int device_speed_thresh[2];
- 
- static void bfq_schedule_dispatch(struct bfq_data *bfqd);
- 
--#include "bfq-ioc.c"
-+/**
-+ * icq_to_bic - convert iocontext queue structure to bfq_io_cq.
-+ * @icq: the iocontext queue.
-+ */
-+static struct bfq_io_cq *icq_to_bic(struct io_cq *icq)
-+{
-+	/* bic->icq is the first member, %NULL will convert to %NULL */
-+	return container_of(icq, struct bfq_io_cq, icq);
-+}
-+
-+/**
-+ * bfq_bic_lookup - search into @ioc a bic associated to @bfqd.
-+ * @bfqd: the lookup key.
-+ * @ioc: the io_context of the process doing I/O.
-+ * @q: the request queue.
-+ */
-+static struct bfq_io_cq *bfq_bic_lookup(struct bfq_data *bfqd,
-+					struct io_context *ioc,
-+					struct request_queue *q)
-+{
-+	if (ioc) {
-+		struct bfq_io_cq *icq;
-+
-+		spin_lock_irq(q->queue_lock);
-+		icq = icq_to_bic(ioc_lookup_icq(ioc, q));
-+		spin_unlock_irq(q->queue_lock);
-+
-+		return icq;
-+	}
-+
-+	return NULL;
-+}
-+
- #include "bfq-sched.c"
- #include "bfq-cgroup-included.c"
- 
-@@ -1520,13 +1552,14 @@ static void bfq_add_request(struct request *rq)
- }
- 
- static struct request *bfq_find_rq_fmerge(struct bfq_data *bfqd,
--					  struct bio *bio)
-+					  struct bio *bio,
-+					  struct request_queue *q)
- {
- 	struct task_struct *tsk = current;
- 	struct bfq_io_cq *bic;
- 	struct bfq_queue *bfqq;
- 
--	bic = bfq_bic_lookup(bfqd, tsk->io_context);
-+	bic = bfq_bic_lookup(bfqd, tsk->io_context, q);
- 	if (!bic)
- 		return NULL;
- 
-
-From ed0d64e27b2308813a2a846139e405e0479f0849 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Tue, 20 Dec 2016 09:07:19 +0100
-Subject: [PATCH 12/51] Modify interface and operation to comply with
- blk-mq-sched
-
-As for modifications of the operation, the major changes are the introduction
-of a scheduler lock, and the moving to deferred work of the body of the hook
-exit_icq. The latter change has been made to avoid deadlocks caused by the
-combination of the following facts: 1) such a body  takes the scheduler lock,
-and, if not deferred, 2) it does so from inside the exit_icq hook, which is
-invoked with the queue lock held, and 3) there is at least one code path,
-namely that starting from bfq_bio_merge, which takes these locks in the
-opposite order.
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-cgroup-included.c |   4 -
- block/bfq-mq-iosched.c      | 695 ++++++++++++++++++++++++--------------------
- block/bfq-mq.h              |  35 +--
- 3 files changed, 394 insertions(+), 340 deletions(-)
-
-diff --git a/block/bfq-cgroup-included.c b/block/bfq-cgroup-included.c
-index 9c483b658179..8a73de76f32b 100644
---- a/block/bfq-cgroup-included.c
-+++ b/block/bfq-cgroup-included.c
-@@ -472,8 +472,6 @@ static struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd,
- 	struct bfq_group *bfqg, *parent;
- 	struct bfq_entity *entity;
- 
--	assert_spin_locked(bfqd->queue->queue_lock);
--
- 	bfqg = bfq_lookup_bfqg(bfqd, blkcg);
- 
- 	if (unlikely(!bfqg))
-@@ -602,8 +600,6 @@ static struct bfq_group *__bfq_bic_change_cgroup(struct bfq_data *bfqd,
- 	struct bfq_group *bfqg;
- 	struct bfq_entity *entity;
- 
--	lockdep_assert_held(bfqd->queue->queue_lock);
--
- 	bfqg = bfq_find_set_group(bfqd, blkcg);
- 
- 	if (unlikely(!bfqg))
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 756a618d5902..c963d92a32c2 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -81,7 +81,13 @@
- #include <linux/jiffies.h>
- #include <linux/rbtree.h>
- #include <linux/ioprio.h>
-+#include <linux/sbitmap.h>
-+#include <linux/delay.h>
-+
- #include "blk.h"
-+#include "blk-mq.h"
-+#include "blk-mq-tag.h"
-+#include "blk-mq-sched.h"
- #undef CONFIG_BFQ_GROUP_IOSCHED /* cgroups support not yet functional */
- #include "bfq-mq.h"
- 
-@@ -193,8 +199,6 @@ static int device_speed_thresh[2];
- #define RQ_BIC(rq)		((struct bfq_io_cq *) (rq)->elv.priv[0])
- #define RQ_BFQQ(rq)		((rq)->elv.priv[1])
- 
--static void bfq_schedule_dispatch(struct bfq_data *bfqd);
--
- /**
-  * icq_to_bic - convert iocontext queue structure to bfq_io_cq.
-  * @icq: the iocontext queue.
-@@ -216,11 +220,12 @@ static struct bfq_io_cq *bfq_bic_lookup(struct bfq_data *bfqd,
- 					struct request_queue *q)
- {
- 	if (ioc) {
-+		unsigned long flags;
- 		struct bfq_io_cq *icq;
- 
--		spin_lock_irq(q->queue_lock);
-+		spin_lock_irqsave(q->queue_lock, flags);
- 		icq = icq_to_bic(ioc_lookup_icq(ioc, q));
--		spin_unlock_irq(q->queue_lock);
-+		spin_unlock_irqrestore(q->queue_lock, flags);
- 
- 		return icq;
- 	}
-@@ -244,7 +249,7 @@ static void bfq_schedule_dispatch(struct bfq_data *bfqd)
- {
- 	if (bfqd->queued != 0) {
- 		bfq_log(bfqd, "schedule dispatch");
--		kblockd_schedule_work(&bfqd->unplug_work);
-+		blk_mq_run_hw_queues(bfqd->queue, true);
- 	}
- }
- 
-@@ -768,9 +773,7 @@ static int bfqq_process_refs(struct bfq_queue *bfqq)
- {
- 	int process_refs, io_refs;
- 
--	lockdep_assert_held(bfqq->bfqd->queue->queue_lock);
--
--	io_refs = bfqq->allocated[READ] + bfqq->allocated[WRITE];
-+	io_refs = bfqq->allocated;
- 	process_refs = bfqq->ref - io_refs - bfqq->entity.on_st;
- 	BUG_ON(process_refs < 0);
- 	return process_refs;
-@@ -1584,6 +1587,7 @@ static sector_t get_sdist(sector_t last_pos, struct request *rq)
- 	return sdist;
- }
- 
-+#if 0 /* Still not clear if we can do without next two functions */
- static void bfq_activate_request(struct request_queue *q, struct request *rq)
- {
- 	struct bfq_data *bfqd = q->elevator->elevator_data;
-@@ -1597,8 +1601,10 @@ static void bfq_deactivate_request(struct request_queue *q, struct request *rq)
- 	BUG_ON(bfqd->rq_in_driver == 0);
- 	bfqd->rq_in_driver--;
- }
-+#endif
- 
--static void bfq_remove_request(struct request *rq)
-+static void bfq_remove_request(struct request_queue *q,
-+			       struct request *rq)
- {
- 	struct bfq_queue *bfqq = RQ_BFQQ(rq);
- 	struct bfq_data *bfqd = bfqq->bfqd;
-@@ -1619,6 +1625,10 @@ static void bfq_remove_request(struct request *rq)
- 	bfqd->queued--;
- 	elv_rb_del(&bfqq->sort_list, rq);
- 
-+	elv_rqhash_del(q, rq);
-+	if (q->last_merge == rq)
-+		q->last_merge = NULL;
-+
- 	if (RB_EMPTY_ROOT(&bfqq->sort_list)) {
- 		bfqq->next_rq = NULL;
- 
-@@ -1659,13 +1669,36 @@ static void bfq_remove_request(struct request *rq)
- 	bfqg_stats_update_io_remove(bfqq_group(bfqq), rq->cmd_flags);
- }
- 
--static enum elv_merge bfq_merge(struct request_queue *q, struct request **req,
--				struct bio *bio)
-+static bool bfq_bio_merge(struct blk_mq_hw_ctx *hctx, struct bio *bio)
-+{
-+	struct request_queue *q = hctx->queue;
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	struct request *free = NULL;
-+	bool ret;
-+
-+	spin_lock_irq(&bfqd->lock);
-+	ret = blk_mq_sched_try_merge(q, bio, &free);
-+
-+	/*
-+	 * XXX Not yet freeing without lock held, to avoid an
-+	 * inconsistency with respect to the lock-protected invocation
-+	 * of blk_mq_sched_try_insert_merge in bfq_bio_merge. Waiting
-+	 * for clarifications from Jens.
-+	 */
-+	if (free)
-+		blk_mq_free_request(free);
-+	spin_unlock_irq(&bfqd->lock);
-+
-+	return ret;
-+}
-+
-+static int bfq_request_merge(struct request_queue *q, struct request **req,
-+			     struct bio *bio)
- {
- 	struct bfq_data *bfqd = q->elevator->elevator_data;
- 	struct request *__rq;
- 
--	__rq = bfq_find_rq_fmerge(bfqd, bio);
-+	__rq = bfq_find_rq_fmerge(bfqd, bio, q);
- 	if (__rq && elv_bio_merge_ok(__rq, bio)) {
- 		*req = __rq;
- 		return ELEVATOR_FRONT_MERGE;
-@@ -1674,7 +1707,7 @@ static enum elv_merge bfq_merge(struct request_queue *q, struct request **req,
- 	return ELEVATOR_NO_MERGE;
- }
- 
--static void bfq_merged_request(struct request_queue *q, struct request *req,
-+static void bfq_request_merged(struct request_queue *q, struct request *req,
- 			       enum elv_merge type)
- {
- 	if (type == ELEVATOR_FRONT_MERGE &&
-@@ -1689,6 +1722,8 @@ static void bfq_merged_request(struct request_queue *q, struct request *req,
- 		/* Reposition request in its sort_list */
- 		elv_rb_del(&bfqq->sort_list, req);
- 		elv_rb_add(&bfqq->sort_list, req);
-+
-+		spin_lock_irq(&bfqd->lock);
- 		/* Choose next request to be served for bfqq */
- 		prev = bfqq->next_rq;
- 		next_rq = bfq_choose_req(bfqd, bfqq->next_rq, req,
-@@ -1704,22 +1739,19 @@ static void bfq_merged_request(struct request_queue *q, struct request *req,
- 			bfq_updated_next_req(bfqd, bfqq);
- 			bfq_pos_tree_add_move(bfqd, bfqq);
- 		}
-+		spin_unlock_irq(&bfqd->lock);
- 	}
- }
- 
--#ifdef BFQ_GROUP_IOSCHED_ENABLED
--static void bfq_bio_merged(struct request_queue *q, struct request *req,
--			   struct bio *bio)
--{
--	bfqg_stats_update_io_merged(bfqq_group(RQ_BFQQ(req)), bio->bi_opf);
--}
--#endif
--
--static void bfq_merged_requests(struct request_queue *q, struct request *rq,
-+static void bfq_requests_merged(struct request_queue *q, struct request *rq,
- 				struct request *next)
- {
- 	struct bfq_queue *bfqq = RQ_BFQQ(rq), *next_bfqq = RQ_BFQQ(next);
- 
-+	if (!RB_EMPTY_NODE(&rq->rb_node))
-+		goto end;
-+	spin_lock_irq(&bfqq->bfqd->lock);
-+
- 	/*
- 	 * If next and rq belong to the same bfq_queue and next is older
- 	 * than rq, then reposition rq in the fifo (by substituting next
-@@ -1740,7 +1772,10 @@ static void bfq_merged_requests(struct request_queue *q, struct request *rq,
- 	if (bfqq->next_rq == next)
- 		bfqq->next_rq = rq;
- 
--	bfq_remove_request(next);
-+	bfq_remove_request(q, next);
-+
-+	spin_unlock_irq(&bfqq->bfqd->lock);
-+end:
- 	bfqg_stats_update_io_merged(bfqq_group(bfqq), next->cmd_flags);
- }
- 
-@@ -1786,7 +1821,7 @@ static void bfq_end_wr(struct bfq_data *bfqd)
- {
- 	struct bfq_queue *bfqq;
- 
--	spin_lock_irq(bfqd->queue->queue_lock);
-+	spin_lock_irq(&bfqd->lock);
- 
- 	list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list)
- 		bfq_bfqq_end_wr(bfqq);
-@@ -1794,7 +1829,7 @@ static void bfq_end_wr(struct bfq_data *bfqd)
- 		bfq_bfqq_end_wr(bfqq);
- 	bfq_end_wr_async(bfqd);
- 
--	spin_unlock_irq(bfqd->queue->queue_lock);
-+	spin_unlock_irq(&bfqd->lock);
- }
- 
- static sector_t bfq_io_struct_pos(void *io_struct, bool request)
-@@ -2184,8 +2219,8 @@ bfq_merge_bfqqs(struct bfq_data *bfqd, struct bfq_io_cq *bic,
- 	bfq_put_queue(bfqq);
- }
- 
--static int bfq_allow_bio_merge(struct request_queue *q, struct request *rq,
--			       struct bio *bio)
-+static bool bfq_allow_bio_merge(struct request_queue *q, struct request *rq,
-+				struct bio *bio)
- {
- 	struct bfq_data *bfqd = q->elevator->elevator_data;
- 	bool is_sync = op_is_sync(bio->bi_opf);
-@@ -2203,7 +2238,7 @@ static int bfq_allow_bio_merge(struct request_queue *q, struct request *rq,
- 	 * merge only if rq is queued there.
- 	 * Queue lock is held here.
- 	 */
--	bic = bfq_bic_lookup(bfqd, current->io_context);
-+	bic = bfq_bic_lookup(bfqd, current->io_context, q);
- 	if (!bic)
- 		return false;
- 
-@@ -2228,12 +2263,6 @@ static int bfq_allow_bio_merge(struct request_queue *q, struct request *rq,
- 	return bfqq == RQ_BFQQ(rq);
- }
- 
--static int bfq_allow_rq_merge(struct request_queue *q, struct request *rq,
--			      struct request *next)
--{
--	return RQ_BFQQ(rq) == RQ_BFQQ(next);
--}
--
- /*
-  * Set the maximum time for the in-service queue to consume its
-  * budget. This prevents seeky processes from lowering the throughput.
-@@ -2264,7 +2293,6 @@ static void __bfq_set_in_service_queue(struct bfq_data *bfqd,
- {
- 	if (bfqq) {
- 		bfqg_stats_update_avg_queue_size(bfqq_group(bfqq));
--		bfq_mark_bfqq_must_alloc(bfqq);
- 		bfq_clear_bfqq_fifo_expire(bfqq);
- 
- 		bfqd->budgets_assigned = (bfqd->budgets_assigned*7 + 256) / 8;
-@@ -2703,27 +2731,28 @@ static void bfq_update_peak_rate(struct bfq_data *bfqd, struct request *rq)
- }
- 
- /*
-- * Move request from internal lists to the dispatch list of the request queue
-+ * Remove request from internal lists.
-  */
--static void bfq_dispatch_insert(struct request_queue *q, struct request *rq)
-+static void bfq_dispatch_remove(struct request_queue *q, struct request *rq)
- {
- 	struct bfq_queue *bfqq = RQ_BFQQ(rq);
- 
- 	/*
--	 * For consistency, the next instruction should have been executed
--	 * after removing the request from the queue and dispatching it.
--	 * We execute instead this instruction before bfq_remove_request()
--	 * (and hence introduce a temporary inconsistency), for efficiency.
--	 * In fact, in a forced_dispatch, this prevents two counters related
--	 * to bfqq->dispatched to risk to be uselessly decremented if bfqq
--	 * is not in service, and then to be incremented again after
--	 * incrementing bfqq->dispatched.
-+	 * For consistency, the next instruction should have been
-+	 * executed after removing the request from the queue and
-+	 * dispatching it.  We execute instead this instruction before
-+	 * bfq_remove_request() (and hence introduce a temporary
-+	 * inconsistency), for efficiency.  In fact, should this
-+	 * dispatch occur for a non in-service bfqq, this anticipated
-+	 * increment prevents two counters related to bfqq->dispatched
-+	 * from risking to be, first, uselessly decremented, and then
-+	 * incremented again when the (new) value of bfqq->dispatched
-+	 * happens to be taken into account.
- 	 */
- 	bfqq->dispatched++;
- 	bfq_update_peak_rate(q->elevator->elevator_data, rq);
- 
--	bfq_remove_request(rq);
--	elv_dispatch_sort(q, rq);
-+	bfq_remove_request(q, rq);
- }
- 
- static void __bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-@@ -3605,7 +3634,7 @@ static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd)
- 	bfq_log_bfqq(bfqd, bfqq, "select_queue: already in-service queue");
- 
- 	if (bfq_may_expire_for_budg_timeout(bfqq) &&
--	    !hrtimer_active(&bfqd->idle_slice_timer) &&
-+	    !bfq_bfqq_wait_request(bfqq) &&
- 	    !bfq_bfqq_must_idle(bfqq))
- 		goto expire;
- 
-@@ -3641,7 +3670,6 @@ static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd)
- 			 * arrives.
- 			 */
- 			if (bfq_bfqq_wait_request(bfqq)) {
--				BUG_ON(!hrtimer_active(&bfqd->idle_slice_timer));
- 				/*
- 				 * If we get here: 1) at least a new request
- 				 * has arrived but we have not disabled the
-@@ -3668,7 +3696,7 @@ static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd)
- 	 * for a new request, or has requests waiting for a completion and
- 	 * may idle after their completion, then keep it anyway.
- 	 */
--	if (hrtimer_active(&bfqd->idle_slice_timer) ||
-+	if (bfq_bfqq_wait_request(bfqq) ||
- 	    (bfqq->dispatched != 0 && bfq_bfqq_may_idle(bfqq))) {
- 		bfqq = NULL;
- 		goto keep_queue;
-@@ -3753,13 +3781,11 @@ static void bfq_update_wr_data(struct bfq_data *bfqd, struct bfq_queue *bfqq)
- }
- 
- /*
-- * Dispatch one request from bfqq, moving it to the request queue
-- * dispatch list.
-+ * Dispatch next request from bfqq.
-  */
--static int bfq_dispatch_request(struct bfq_data *bfqd,
--				struct bfq_queue *bfqq)
-+static struct request *bfq_dispatch_rq_from_bfqq(struct bfq_data *bfqd,
-+						 struct bfq_queue *bfqq)
- {
--	int dispatched = 0;
- 	struct request *rq = bfqq->next_rq;
- 	unsigned long service_to_charge;
- 
-@@ -3775,7 +3801,7 @@ static int bfq_dispatch_request(struct bfq_data *bfqd,
- 
- 	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
- 
--	bfq_dispatch_insert(bfqd->queue, rq);
-+	bfq_dispatch_remove(bfqd->queue, rq);
- 
- 	/*
- 	 * If weight raising has to terminate for bfqq, then next
-@@ -3791,86 +3817,61 @@ static int bfq_dispatch_request(struct bfq_data *bfqd,
- 	bfq_update_wr_data(bfqd, bfqq);
- 
- 	bfq_log_bfqq(bfqd, bfqq,
--			"dispatched %u sec req (%llu), budg left %d",
-+	     "dispatched %u sec req (%llu), budg left %d, new disp_nr %d",
- 			blk_rq_sectors(rq),
- 			(unsigned long long) blk_rq_pos(rq),
--			bfq_bfqq_budget_left(bfqq));
--
--	dispatched++;
-+		     bfq_bfqq_budget_left(bfqq),
-+		     bfqq->dispatched);
- 
- 	if (!bfqd->in_service_bic) {
- 		atomic_long_inc(&RQ_BIC(rq)->icq.ioc->refcount);
- 		bfqd->in_service_bic = RQ_BIC(rq);
- 	}
- 
-+	/*
-+	 * Expire bfqq, pretending that its budget expired, if bfqq
-+	 * belongs to CLASS_IDLE and other queues are waiting for
-+	 * service.
-+	 */
- 	if (bfqd->busy_queues > 1 && bfq_class_idle(bfqq))
- 		goto expire;
- 
--	return dispatched;
-+	return rq;
- 
- expire:
- 	bfq_bfqq_expire(bfqd, bfqq, false, BFQ_BFQQ_BUDGET_EXHAUSTED);
--	return dispatched;
--}
--
--static int __bfq_forced_dispatch_bfqq(struct bfq_queue *bfqq)
--{
--	int dispatched = 0;
--
--	while (bfqq->next_rq) {
--		bfq_dispatch_insert(bfqq->bfqd->queue, bfqq->next_rq);
--		dispatched++;
--	}
--
--	BUG_ON(!list_empty(&bfqq->fifo));
--	return dispatched;
-+	return rq;
- }
- 
--/*
-- * Drain our current requests.
-- * Used for barriers and when switching io schedulers on-the-fly.
-- */
--static int bfq_forced_dispatch(struct bfq_data *bfqd)
-+static bool bfq_has_work(struct blk_mq_hw_ctx *hctx)
- {
--	struct bfq_queue *bfqq, *n;
--	struct bfq_service_tree *st;
--	int dispatched = 0;
--
--	bfqq = bfqd->in_service_queue;
--	if (bfqq)
--		__bfq_bfqq_expire(bfqd, bfqq);
-+	struct bfq_data *bfqd = hctx->queue->elevator->elevator_data;
- 
- 	/*
--	 * Loop through classes, and be careful to leave the scheduler
--	 * in a consistent state, as feedback mechanisms and vtime
--	 * updates cannot be disabled during the process.
-+	 * Avoiding lock: a race on bfqd->busy_queues should cause at
-+	 * most a call to dispatch for nothing
- 	 */
--	list_for_each_entry_safe(bfqq, n, &bfqd->active_list, bfqq_list) {
--		st = bfq_entity_service_tree(&bfqq->entity);
--
--		dispatched += __bfq_forced_dispatch_bfqq(bfqq);
--
--		bfqq->max_budget = bfq_max_budget(bfqd);
--		bfq_forget_idle(st);
--	}
--
--	BUG_ON(bfqd->busy_queues != 0);
--
--	return dispatched;
-+	return !list_empty_careful(&bfqd->dispatch) ||
-+		bfqd->busy_queues > 0;
- }
- 
--static int bfq_dispatch_requests(struct request_queue *q, int force)
-+static struct request *__bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
- {
--	struct bfq_data *bfqd = q->elevator->elevator_data;
--	struct bfq_queue *bfqq;
-+	struct bfq_data *bfqd = hctx->queue->elevator->elevator_data;
-+	struct request *rq = NULL;
-+	struct bfq_queue *bfqq = NULL;
-+
-+	if (!list_empty(&bfqd->dispatch)) {
-+		rq = list_first_entry(&bfqd->dispatch, struct request,
-+				      queuelist);
-+		list_del_init(&rq->queuelist);
-+		goto exit;
-+	}
- 
- 	bfq_log(bfqd, "dispatch requests: %d busy queues", bfqd->busy_queues);
- 
- 	if (bfqd->busy_queues == 0)
--		return 0;
--
--	if (unlikely(force))
--		return bfq_forced_dispatch(bfqd);
-+		goto exit;
- 
- 	/*
- 	 * Force device to serve one request at a time if
-@@ -3885,25 +3886,39 @@ static int bfq_dispatch_requests(struct request_queue *q, int force)
- 	 * throughput.
- 	 */
- 	if (bfqd->strict_guarantees && bfqd->rq_in_driver > 0)
--		return 0;
-+		goto exit;
- 
- 	bfqq = bfq_select_queue(bfqd);
- 	if (!bfqq)
--		return 0;
-+		goto exit;
- 
- 	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
- 
- 	BUG_ON(bfq_bfqq_wait_request(bfqq));
- 
--	if (!bfq_dispatch_request(bfqd, bfqq))
--		return 0;
--
--	bfq_log_bfqq(bfqd, bfqq, "dispatched %s request",
--			bfq_bfqq_sync(bfqq) ? "sync" : "async");
-+	rq = bfq_dispatch_rq_from_bfqq(bfqd, bfqq);
- 
- 	BUG_ON(bfqq->next_rq == NULL &&
- 	       bfqq->entity.budget < bfqq->entity.service);
--	return 1;
-+exit:
-+	if (rq) {
-+		rq->rq_flags |= RQF_STARTED;
-+		bfqd->rq_in_driver++;
-+	}
-+
-+	return rq;
-+}
-+
-+static struct request *bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
-+{
-+	struct bfq_data *bfqd = hctx->queue->elevator->elevator_data;
-+	struct request *rq;
-+
-+	spin_lock_irq(&bfqd->lock);
-+	rq = __bfq_dispatch_request(hctx);
-+	spin_unlock_irq(&bfqd->lock);
-+
-+	return rq;
- }
- 
- /*
-@@ -3921,13 +3936,14 @@ static void bfq_put_queue(struct bfq_queue *bfqq)
- 
- 	BUG_ON(bfqq->ref <= 0);
- 
--	bfq_log_bfqq(bfqq->bfqd, bfqq, "put_queue: %p %d", bfqq, bfqq->ref);
-+	if (bfqq->bfqd)
-+		bfq_log_bfqq(bfqq->bfqd, bfqq, "put_queue: %p %d", bfqq, bfqq->ref);
-+
- 	bfqq->ref--;
- 	if (bfqq->ref)
- 		return;
- 
- 	BUG_ON(rb_first(&bfqq->sort_list));
--	BUG_ON(bfqq->allocated[READ] + bfqq->allocated[WRITE] != 0);
- 	BUG_ON(bfqq->entity.tree);
- 	BUG_ON(bfq_bfqq_busy(bfqq));
- 
-@@ -3942,7 +3958,8 @@ static void bfq_put_queue(struct bfq_queue *bfqq)
- 		 */
- 		hlist_del_init(&bfqq->burst_list_node);
- 
--	bfq_log_bfqq(bfqq->bfqd, bfqq, "put_queue: %p freed", bfqq);
-+	if (bfqq->bfqd)
-+		bfq_log_bfqq(bfqq->bfqd, bfqq, "put_queue: %p freed", bfqq);
- 
- 	kmem_cache_free(bfq_pool, bfqq);
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
-@@ -3983,29 +4000,52 @@ static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
- 	bfq_put_queue(bfqq); /* release process reference */
- }
- 
--static void bfq_exit_icq(struct io_cq *icq)
-+static void bfq_exit_icq_bfqq(struct bfq_io_cq *bic, bool is_sync)
- {
--	struct bfq_io_cq *bic = icq_to_bic(icq);
--	struct bfq_data *bfqd = bic_to_bfqd(bic);
-+	struct bfq_queue *bfqq = bic_to_bfqq(bic, is_sync);
-+	struct bfq_data *bfqd;
- 
--	if (bic_to_bfqq(bic, false)) {
--		bfq_exit_bfqq(bfqd, bic_to_bfqq(bic, false));
--		bic_set_bfqq(bic, NULL, false);
--	}
-+	if (bfqq)
-+		bfqd = bfqq->bfqd; /* NULL if scheduler already exited */
- 
--	if (bic_to_bfqq(bic, true)) {
-+	if (bfqq && bfqd) {
-+		spin_lock_irq(&bfqd->lock);
- 		/*
- 		 * If the bic is using a shared queue, put the reference
- 		 * taken on the io_context when the bic started using a
- 		 * shared bfq_queue.
- 		 */
--		if (bfq_bfqq_coop(bic_to_bfqq(bic, true)))
--			put_io_context(icq->ioc);
--		bfq_exit_bfqq(bfqd, bic_to_bfqq(bic, true));
--		bic_set_bfqq(bic, NULL, true);
-+		if (is_sync && bfq_bfqq_coop(bfqq))
-+			put_io_context(bic->icq.ioc);
-+		bfq_exit_bfqq(bfqd, bfqq);
-+		bic_set_bfqq(bic, NULL, is_sync);
-+		spin_unlock_irq(&bfqd->lock);
- 	}
- }
- 
-+static void bfq_exit_icq_body(struct work_struct *work)
-+{
-+	struct bfq_io_cq *bic =
-+		container_of(work, struct bfq_io_cq, exit_icq_work);
-+
-+	bfq_exit_icq_bfqq(bic, true);
-+	bfq_exit_icq_bfqq(bic, false);
-+}
-+
-+static void bfq_init_icq(struct io_cq *icq)
-+{
-+	struct bfq_io_cq *bic = icq_to_bic(icq);
-+
-+	INIT_WORK(&bic->exit_icq_work, bfq_exit_icq_body);
-+}
-+
-+static void bfq_exit_icq(struct io_cq *icq)
-+{
-+	struct bfq_io_cq *bic = icq_to_bic(icq);
-+
-+	kblockd_schedule_work(&bic->exit_icq_work);
-+}
-+
- /*
-  * Update the entity prio values; note that the new values will not
-  * be used until the next (re)activation.
-@@ -4015,6 +4055,10 @@ static void bfq_set_next_ioprio_data(struct bfq_queue *bfqq,
- {
- 	struct task_struct *tsk = current;
- 	int ioprio_class;
-+	struct bfq_data *bfqd = bfqq->bfqd;
-+
-+	if (!bfqd)
-+		return;
- 
- 	ioprio_class = IOPRIO_PRIO_CLASS(bic->ioprio);
- 	switch (ioprio_class) {
-@@ -4095,6 +4139,8 @@ static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 	INIT_HLIST_NODE(&bfqq->burst_list_node);
- 	BUG_ON(!hlist_unhashed(&bfqq->burst_list_node));
- 
-+	spin_lock_init(&bfqq->lock);
-+
- 	bfqq->ref = 0;
- 	bfqq->bfqd = bfqd;
- 
-@@ -4351,22 +4397,13 @@ static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 		if (budget_timeout)
- 			bfq_bfqq_expire(bfqd, bfqq, false,
- 					BFQ_BFQQ_BUDGET_TIMEOUT);
--
--		/*
--		 * Let the request rip immediately, or let a new queue be
--		 * selected if bfqq has just been expired.
--		 */
--		__blk_run_queue(bfqd->queue);
- 	}
- }
- 
--static void bfq_insert_request(struct request_queue *q, struct request *rq)
-+static void __bfq_insert_request(struct bfq_data *bfqd, struct request *rq)
- {
--	struct bfq_data *bfqd = q->elevator->elevator_data;
- 	struct bfq_queue *bfqq = RQ_BFQQ(rq), *new_bfqq;
- 
--	assert_spin_locked(bfqd->queue->queue_lock);
--
- 	/*
- 	 * An unplug may trigger a requeue of a request from the device
- 	 * driver: make sure we are in process context while trying to
-@@ -4381,8 +4418,8 @@ static void bfq_insert_request(struct request_queue *q, struct request *rq)
- 			 * Release the request's reference to the old bfqq
- 			 * and make sure one is taken to the shared queue.
- 			 */
--			new_bfqq->allocated[rq_data_dir(rq)]++;
--			bfqq->allocated[rq_data_dir(rq)]--;
-+			new_bfqq->allocated++;
-+			bfqq->allocated--;
- 			new_bfqq->ref++;
- 			bfq_clear_bfqq_just_created(bfqq);
- 			if (bic_to_bfqq(RQ_BIC(rq), 1) == bfqq)
-@@ -4406,6 +4443,55 @@ static void bfq_insert_request(struct request_queue *q, struct request *rq)
- 	bfq_rq_enqueued(bfqd, bfqq, rq);
- }
- 
-+static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
-+			      bool at_head)
-+{
-+	struct request_queue *q = hctx->queue;
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+
-+	spin_lock_irq(&bfqd->lock);
-+	if (blk_mq_sched_try_insert_merge(q, rq))
-+		goto done;
-+	spin_unlock_irq(&bfqd->lock);
-+
-+	blk_mq_sched_request_inserted(rq);
-+
-+	spin_lock_irq(&bfqd->lock);
-+	if (at_head || blk_rq_is_passthrough(rq)) {
-+		struct bfq_queue *bfqq = RQ_BFQQ(rq);
-+
-+		if (at_head)
-+			list_add(&rq->queuelist, &bfqd->dispatch);
-+		else
-+			list_add_tail(&rq->queuelist, &bfqd->dispatch);
-+
-+		if (bfqq)
-+			bfqq->dispatched++;
-+	} else {
-+		__bfq_insert_request(bfqd, rq);
-+
-+		if (rq_mergeable(rq)) {
-+			elv_rqhash_add(q, rq);
-+			if (!q->last_merge)
-+				q->last_merge = rq;
-+		}
-+	}
-+done:
-+	spin_unlock_irq(&bfqd->lock);
-+}
-+
-+static void bfq_insert_requests(struct blk_mq_hw_ctx *hctx,
-+				struct list_head *list, bool at_head)
-+{
-+	while (!list_empty(list)) {
-+		struct request *rq;
-+
-+		rq = list_first_entry(list, struct request, queuelist);
-+		list_del_init(&rq->queuelist);
-+		bfq_insert_request(hctx, rq, at_head);
-+	}
-+}
-+
- static void bfq_update_hw_tag(struct bfq_data *bfqd)
- {
- 	bfqd->max_rq_in_driver = max_t(int, bfqd->max_rq_in_driver,
-@@ -4431,27 +4517,17 @@ static void bfq_update_hw_tag(struct bfq_data *bfqd)
- 	bfqd->hw_tag_samples = 0;
- }
- 
--static void bfq_completed_request(struct request_queue *q, struct request *rq)
-+static void bfq_completed_request(struct bfq_queue *bfqq, struct bfq_data *bfqd)
- {
--	struct bfq_queue *bfqq = RQ_BFQQ(rq);
--	struct bfq_data *bfqd = bfqq->bfqd;
- 	u64 now_ns;
- 	u32 delta_us;
- 
--	bfq_log_bfqq(bfqd, bfqq, "completed one req with %u sects left",
--		     blk_rq_sectors(rq));
--
--	assert_spin_locked(bfqd->queue->queue_lock);
- 	bfq_update_hw_tag(bfqd);
- 
- 	BUG_ON(!bfqd->rq_in_driver);
- 	BUG_ON(!bfqq->dispatched);
- 	bfqd->rq_in_driver--;
- 	bfqq->dispatched--;
--	bfqg_stats_update_completion(bfqq_group(bfqq),
--				     rq_start_time_ns(rq),
--				     rq_io_start_time_ns(rq),
--				     rq->cmd_flags);
- 
- 	if (!bfqq->dispatched && !bfq_bfqq_busy(bfqq)) {
- 		BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list));
-@@ -4477,7 +4553,8 @@ static void bfq_completed_request(struct request_queue *q, struct request *rq)
- 	 */
- 	delta_us = div_u64(now_ns - bfqd->last_completion, NSEC_PER_USEC);
- 
--	bfq_log(bfqd, "rq_completed: delta %uus/%luus max_size %u rate %llu/%llu",
-+	bfq_log_bfqq(bfqd, bfqq,
-+		"rq_completed: delta %uus/%luus max_size %u rate %llu/%llu",
- 		delta_us, BFQ_MIN_TT/NSEC_PER_USEC, bfqd->last_rq_max_size,
- 		(USEC_PER_SEC*
- 		(u64)((bfqd->last_rq_max_size<<BFQ_RATE_SHIFT)/delta_us))
-@@ -4527,7 +4604,7 @@ static void bfq_completed_request(struct request_queue *q, struct request *rq)
- 	if (bfqd->in_service_queue == bfqq) {
- 		if (bfqq->dispatched == 0 && bfq_bfqq_must_idle(bfqq)) {
- 			bfq_arm_slice_timer(bfqd);
--			goto out;
-+			return;
- 		} else if (bfq_may_expire_for_budg_timeout(bfqq))
- 			bfq_bfqq_expire(bfqd, bfqq, false,
- 					BFQ_BFQQ_BUDGET_TIMEOUT);
-@@ -4537,68 +4614,55 @@ static void bfq_completed_request(struct request_queue *q, struct request *rq)
- 			bfq_bfqq_expire(bfqd, bfqq, false,
- 					BFQ_BFQQ_NO_MORE_REQUESTS);
- 	}
--
--	if (!bfqd->rq_in_driver)
--		bfq_schedule_dispatch(bfqd);
--
--out:
--	return;
- }
- 
--static int __bfq_may_queue(struct bfq_queue *bfqq)
-+static void bfq_put_rq_priv_body(struct bfq_queue *bfqq)
- {
--	if (bfq_bfqq_wait_request(bfqq) && bfq_bfqq_must_alloc(bfqq)) {
--		bfq_clear_bfqq_must_alloc(bfqq);
--		return ELV_MQUEUE_MUST;
--	}
-+	bfqq->allocated--;
- 
--	return ELV_MQUEUE_MAY;
-+	bfq_put_queue(bfqq);
- }
- 
--static int bfq_may_queue(struct request_queue *q, unsigned int op)
-+static void bfq_put_rq_private(struct request_queue *q, struct request *rq)
- {
--	struct bfq_data *bfqd = q->elevator->elevator_data;
--	struct task_struct *tsk = current;
--	struct bfq_io_cq *bic;
--	struct bfq_queue *bfqq;
--
--	/*
--	 * Don't force setup of a queue from here, as a call to may_queue
--	 * does not necessarily imply that a request actually will be
--	 * queued. So just lookup a possibly existing queue, or return
--	 * 'may queue' if that fails.
--	 */
--	bic = bfq_bic_lookup(bfqd, tsk->io_context);
--	if (!bic)
--		return ELV_MQUEUE_MAY;
--
--	bfqq = bic_to_bfqq(bic, op_is_sync(op));
--	if (bfqq)
--		return __bfq_may_queue(bfqq);
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq);
-+	struct bfq_data *bfqd = bfqq->bfqd;
- 
--	return ELV_MQUEUE_MAY;
--}
-+	if (rq->rq_flags & RQF_STARTED)
-+		bfqg_stats_update_completion(bfqq_group(bfqq),
-+					     rq_start_time_ns(rq),
-+					     rq_io_start_time_ns(rq),
-+					     rq->cmd_flags);
- 
--/*
-- * Queue lock held here.
-- */
--static void bfq_put_request(struct request *rq)
--{
--	struct bfq_queue *bfqq = RQ_BFQQ(rq);
-+	if (likely(rq->rq_flags & RQF_STARTED)) {
-+		unsigned long flags;
- 
--	if (bfqq) {
--		const int rw = rq_data_dir(rq);
-+		spin_lock_irqsave(&bfqd->lock, flags);
- 
--		BUG_ON(!bfqq->allocated[rw]);
--		bfqq->allocated[rw]--;
-+		bfq_completed_request(bfqq, bfqd);
-+		bfq_put_rq_priv_body(bfqq);
- 
--		rq->elv.priv[0] = NULL;
--		rq->elv.priv[1] = NULL;
-+		spin_unlock_irqrestore(&bfqd->lock, flags);
-+	} else {
-+		/*
-+		 * Request rq may be still/already in the scheduler,
-+		 * in which case we need to remove it. And we cannot
-+		 * defer such a check and removal, to avoid
-+		 * inconsistencies in the time interval from the end
-+		 * of this function to the start of the deferred work.
-+		 * Fortunately, this situation occurs only in process
-+		 * context, so taking the scheduler lock does not
-+		 * cause any deadlock, even if other locks are already
-+		 * (correctly) held by this process.
-+		 */
- 
--		bfq_log_bfqq(bfqq->bfqd, bfqq, "put_request %p, %d",
--			     bfqq, bfqq->ref);
--		bfq_put_queue(bfqq);
-+		if (!RB_EMPTY_NODE(&rq->rb_node))
-+			bfq_remove_request(q, rq);
-+		bfq_put_rq_priv_body(bfqq);
- 	}
-+
-+	rq->elv.priv[0] = NULL;
-+	rq->elv.priv[1] = NULL;
- }
- 
- /*
-@@ -4630,18 +4694,16 @@ bfq_split_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq)
- /*
-  * Allocate bfq data structures associated with this request.
-  */
--static int bfq_set_request(struct request_queue *q, struct request *rq,
--			   struct bio *bio, gfp_t gfp_mask)
-+static int bfq_get_rq_private(struct request_queue *q, struct request *rq,
-+			      struct bio *bio)
- {
- 	struct bfq_data *bfqd = q->elevator->elevator_data;
- 	struct bfq_io_cq *bic = icq_to_bic(rq->elv.icq);
--	const int rw = rq_data_dir(rq);
- 	const int is_sync = rq_is_sync(rq);
- 	struct bfq_queue *bfqq;
--	unsigned long flags;
- 	bool bfqq_already_existing = false, split = false;
- 
--	spin_lock_irqsave(q->queue_lock, flags);
-+	spin_lock_irq(&bfqd->lock);
- 
- 	if (!bic)
- 		goto queue_fail;
-@@ -4661,7 +4723,7 @@ static int bfq_set_request(struct request_queue *q, struct request *rq,
- 		bic_set_bfqq(bic, bfqq, is_sync);
- 		if (split && is_sync) {
- 			bfq_log_bfqq(bfqd, bfqq,
--				     "set_request: was_in_list %d "
-+				     "get_request: was_in_list %d "
- 				     "was_in_large_burst %d "
- 				     "large burst in progress %d",
- 				     bic->was_in_burst_list,
-@@ -4671,12 +4733,12 @@ static int bfq_set_request(struct request_queue *q, struct request *rq,
- 			if ((bic->was_in_burst_list && bfqd->large_burst) ||
- 			    bic->saved_in_large_burst) {
- 				bfq_log_bfqq(bfqd, bfqq,
--					     "set_request: marking in "
-+					     "get_request: marking in "
- 					     "large burst");
- 				bfq_mark_bfqq_in_large_burst(bfqq);
- 			} else {
- 				bfq_log_bfqq(bfqd, bfqq,
--					     "set_request: clearing in "
-+					     "get_request: clearing in "
- 					     "large burst");
- 				bfq_clear_bfqq_in_large_burst(bfqq);
- 				if (bic->was_in_burst_list)
-@@ -4703,9 +4765,12 @@ static int bfq_set_request(struct request_queue *q, struct request *rq,
- 		}
- 	}
- 
--	bfqq->allocated[rw]++;
-+	bfqq->allocated++;
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		     "get_request: new allocated %d", bfqq->allocated);
-+
- 	bfqq->ref++;
--	bfq_log_bfqq(bfqd, bfqq, "set_request: bfqq %p, %d", bfqq, bfqq->ref);
-+	bfq_log_bfqq(bfqd, bfqq, "get_request: bfqq %p, %d", bfqq, bfqq->ref);
- 
- 	rq->elv.priv[0] = bic;
- 	rq->elv.priv[1] = bfqq;
-@@ -4733,26 +4798,53 @@ static int bfq_set_request(struct request_queue *q, struct request *rq,
- 	if (unlikely(bfq_bfqq_just_created(bfqq)))
- 		bfq_handle_burst(bfqd, bfqq);
- 
--	spin_unlock_irqrestore(q->queue_lock, flags);
-+	spin_unlock_irq(&bfqd->lock);
- 
- 	return 0;
- 
- queue_fail:
--	bfq_schedule_dispatch(bfqd);
--	spin_unlock_irqrestore(q->queue_lock, flags);
-+	spin_unlock_irq(&bfqd->lock);
- 
- 	return 1;
- }
- 
--static void bfq_kick_queue(struct work_struct *work)
-+static void bfq_idle_slice_timer_body(struct bfq_queue *bfqq)
- {
--	struct bfq_data *bfqd =
--		container_of(work, struct bfq_data, unplug_work);
--	struct request_queue *q = bfqd->queue;
-+	struct bfq_data *bfqd = bfqq->bfqd;
-+	enum bfqq_expiration reason;
-+	unsigned long flags;
-+
-+	spin_lock_irqsave(&bfqd->lock, flags);
-+	bfq_clear_bfqq_wait_request(bfqq);
- 
--	spin_lock_irq(q->queue_lock);
--	__blk_run_queue(q);
--	spin_unlock_irq(q->queue_lock);
-+	if (bfqq != bfqd->in_service_queue) {
-+		spin_unlock_irqrestore(&bfqd->lock, flags);
-+		return;
-+	}
-+
-+	if (bfq_bfqq_budget_timeout(bfqq))
-+		/*
-+		 * Also here the queue can be safely expired
-+		 * for budget timeout without wasting
-+		 * guarantees
-+		 */
-+		reason = BFQ_BFQQ_BUDGET_TIMEOUT;
-+	else if (bfqq->queued[0] == 0 && bfqq->queued[1] == 0)
-+		/*
-+		 * The queue may not be empty upon timer expiration,
-+		 * because we may not disable the timer when the
-+		 * first request of the in-service queue arrives
-+		 * during disk idling.
-+		 */
-+		reason = BFQ_BFQQ_TOO_IDLE;
-+	else
-+		goto schedule_dispatch;
-+
-+	bfq_bfqq_expire(bfqd, bfqq, true, reason);
-+
-+schedule_dispatch:
-+	spin_unlock_irqrestore(&bfqd->lock, flags);
-+	bfq_schedule_dispatch(bfqd);
- }
- 
- /*
-@@ -4763,59 +4855,22 @@ static enum hrtimer_restart bfq_idle_slice_timer(struct hrtimer *timer)
- {
- 	struct bfq_data *bfqd = container_of(timer, struct bfq_data,
- 					     idle_slice_timer);
--	struct bfq_queue *bfqq;
--	unsigned long flags;
--	enum bfqq_expiration reason;
--
--	spin_lock_irqsave(bfqd->queue->queue_lock, flags);
-+	struct bfq_queue *bfqq = bfqd->in_service_queue;
- 
--	bfqq = bfqd->in_service_queue;
- 	/*
- 	 * Theoretical race here: the in-service queue can be NULL or
--	 * different from the queue that was idling if the timer handler
--	 * spins on the queue_lock and a new request arrives for the
--	 * current queue and there is a full dispatch cycle that changes
--	 * the in-service queue.  This can hardly happen, but in the worst
--	 * case we just expire a queue too early.
-+	 * different from the queue that was idling if a new request
-+	 * arrives for the current queue and there is a full dispatch
-+	 * cycle that changes the in-service queue.  This can hardly
-+	 * happen, but in the worst case we just expire a queue too
-+	 * early.
- 	 */
--	if (bfqq) {
--		bfq_log_bfqq(bfqd, bfqq, "slice_timer expired");
--		bfq_clear_bfqq_wait_request(bfqq);
--
--		if (bfq_bfqq_budget_timeout(bfqq))
--			/*
--			 * Also here the queue can be safely expired
--			 * for budget timeout without wasting
--			 * guarantees
--			 */
--			reason = BFQ_BFQQ_BUDGET_TIMEOUT;
--		else if (bfqq->queued[0] == 0 && bfqq->queued[1] == 0)
--			/*
--			 * The queue may not be empty upon timer expiration,
--			 * because we may not disable the timer when the
--			 * first request of the in-service queue arrives
--			 * during disk idling.
--			 */
--			reason = BFQ_BFQQ_TOO_IDLE;
--		else
--			goto schedule_dispatch;
--
--		bfq_bfqq_expire(bfqd, bfqq, true, reason);
--	}
--
--schedule_dispatch:
--	bfq_schedule_dispatch(bfqd);
-+	if (bfqq)
-+		bfq_idle_slice_timer_body(bfqq);
- 
--	spin_unlock_irqrestore(bfqd->queue->queue_lock, flags);
- 	return HRTIMER_NORESTART;
- }
- 
--static void bfq_shutdown_timer_wq(struct bfq_data *bfqd)
--{
--	hrtimer_cancel(&bfqd->idle_slice_timer);
--	cancel_work_sync(&bfqd->unplug_work);
--}
--
- static void __bfq_put_async_bfqq(struct bfq_data *bfqd,
- 				 struct bfq_queue **bfqq_ptr)
- {
-@@ -4852,28 +4907,40 @@ static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg)
- static void bfq_exit_queue(struct elevator_queue *e)
- {
- 	struct bfq_data *bfqd = e->elevator_data;
--	struct request_queue *q = bfqd->queue;
- 	struct bfq_queue *bfqq, *n;
- 
--	bfq_shutdown_timer_wq(bfqd);
--
--	spin_lock_irq(q->queue_lock);
-+	hrtimer_cancel(&bfqd->idle_slice_timer);
- 
- 	BUG_ON(bfqd->in_service_queue);
--	list_for_each_entry_safe(bfqq, n, &bfqd->idle_list, bfqq_list)
--		bfq_deactivate_bfqq(bfqd, bfqq, false, false);
- 
--	spin_unlock_irq(q->queue_lock);
-+	list_for_each_entry_safe(bfqq, n, &bfqd->idle_list, bfqq_list) {
-+		if (bfqq->bic) /* bfqqs without bic are handled below */
-+			cancel_work_sync(&bfqq->bic->exit_icq_work);
-+	}
-+
-+	spin_lock_irq(&bfqd->lock);
-+	list_for_each_entry_safe(bfqq, n, &bfqd->idle_list, bfqq_list) {
-+		bfq_deactivate_bfqq(bfqd, bfqq, false, false);
-+		/*
-+		 * Make sure that deferred exit_icq_work completes
-+		 * without errors for bfq_queues without bic
-+		 */
-+		if (!bfqq->bic)
-+			bfqq->bfqd = NULL;
-+	}
-+	spin_unlock_irq(&bfqd->lock);
- 
--	bfq_shutdown_timer_wq(bfqd);
-+	hrtimer_cancel(&bfqd->idle_slice_timer);
- 
- 	BUG_ON(hrtimer_active(&bfqd->idle_slice_timer));
- 
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
--	blkcg_deactivate_policy(q, &blkcg_policy_bfq);
-+	blkcg_deactivate_policy(bfqd->queue, &blkcg_policy_bfq);
- #else
-+	spin_lock_irq(&bfqd->lock);
- 	bfq_put_async_queues(bfqd, bfqd->root_group);
- 	kfree(bfqd->root_group);
-+	spin_unlock_irq(&bfqd->lock);
- #endif
- 
- 	kfree(bfqd);
-@@ -4934,10 +5001,6 @@ static int bfq_init_queue(struct request_queue *q, struct elevator_type *e)
- 
- 	bfqd->queue = q;
- 
--	spin_lock_irq(q->queue_lock);
--	q->elevator = eq;
--	spin_unlock_irq(q->queue_lock);
--
- 	bfqd->root_group = bfq_create_group_hierarchy(bfqd, q->node);
- 	if (!bfqd->root_group)
- 		goto out_free;
-@@ -4951,8 +5014,6 @@ static int bfq_init_queue(struct request_queue *q, struct elevator_type *e)
- 	bfqd->queue_weights_tree = RB_ROOT;
- 	bfqd->group_weights_tree = RB_ROOT;
- 
--	INIT_WORK(&bfqd->unplug_work, bfq_kick_queue);
--
- 	INIT_LIST_HEAD(&bfqd->active_list);
- 	INIT_LIST_HEAD(&bfqd->idle_list);
- 	INIT_HLIST_HEAD(&bfqd->burst_list);
-@@ -5001,6 +5062,11 @@ static int bfq_init_queue(struct request_queue *q, struct elevator_type *e)
- 	bfqd->peak_rate = R_fast[blk_queue_nonrot(bfqd->queue)] * 2 / 3;
- 	bfqd->device_speed = BFQ_BFQD_FAST;
- 
-+	spin_lock_init(&bfqd->lock);
-+	INIT_LIST_HEAD(&bfqd->dispatch);
-+
-+	q->elevator = eq;
-+
- 	return 0;
- 
- out_free:
-@@ -5057,7 +5123,7 @@ static ssize_t bfq_weights_show(struct elevator_queue *e, char *page)
- 	num_char += sprintf(page + num_char, "Tot reqs queued %d\n\n",
- 			    bfqd->queued);
- 
--	spin_lock_irq(bfqd->queue->queue_lock);
-+	spin_lock_irq(&bfqd->lock);
- 
- 	num_char += sprintf(page + num_char, "Active:\n");
- 	list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list) {
-@@ -5086,7 +5152,7 @@ static ssize_t bfq_weights_show(struct elevator_queue *e, char *page)
- 				    jiffies_to_msecs(bfqq->wr_cur_max_time));
- 	}
- 
--	spin_unlock_irq(bfqd->queue->queue_lock);
-+	spin_unlock_irq(&bfqd->lock);
- 
- 	return num_char;
- }
-@@ -5294,35 +5360,31 @@ static struct elv_fs_entry bfq_attrs[] = {
- 	__ATTR_NULL
- };
- 
--static struct elevator_type iosched_bfq = {
--	.ops.sq = {
--		.elevator_merge_fn =		bfq_merge,
--		.elevator_merged_fn =		bfq_merged_request,
--		.elevator_merge_req_fn =	bfq_merged_requests,
--#ifdef BFQ_GROUP_IOSCHED_ENABLED
--		.elevator_bio_merged_fn =	bfq_bio_merged,
--#endif
--		.elevator_allow_bio_merge_fn =	bfq_allow_bio_merge,
--		.elevator_allow_rq_merge_fn =	bfq_allow_rq_merge,
--		.elevator_dispatch_fn =		bfq_dispatch_requests,
--		.elevator_add_req_fn =		bfq_insert_request,
--		.elevator_activate_req_fn =	bfq_activate_request,
--		.elevator_deactivate_req_fn =	bfq_deactivate_request,
--		.elevator_completed_req_fn =	bfq_completed_request,
--		.elevator_former_req_fn =	elv_rb_former_request,
--		.elevator_latter_req_fn =	elv_rb_latter_request,
--		.elevator_init_icq_fn =		bfq_init_icq,
--		.elevator_exit_icq_fn =		bfq_exit_icq,
--		.elevator_set_req_fn =		bfq_set_request,
--		.elevator_put_req_fn =		bfq_put_request,
--		.elevator_may_queue_fn =	bfq_may_queue,
--		.elevator_init_fn =		bfq_init_queue,
--		.elevator_exit_fn =		bfq_exit_queue,
-+static struct elevator_type iosched_bfq_mq = {
-+	.ops.mq = {
-+		.get_rq_priv		= bfq_get_rq_private,
-+		.put_rq_priv		= bfq_put_rq_private,
-+		.init_icq		= bfq_init_icq,
-+		.exit_icq		= bfq_exit_icq,
-+		.insert_requests	= bfq_insert_requests,
-+		.dispatch_request	= bfq_dispatch_request,
-+		.next_request		= elv_rb_latter_request,
-+		.former_request		= elv_rb_former_request,
-+		.allow_merge		= bfq_allow_bio_merge,
-+		.bio_merge		= bfq_bio_merge,
-+		.request_merge		= bfq_request_merge,
-+		.requests_merged	= bfq_requests_merged,
-+		.request_merged		= bfq_request_merged,
-+		.has_work		= bfq_has_work,
-+		.init_sched		= bfq_init_queue,
-+		.exit_sched		= bfq_exit_queue,
- 	},
-+
-+	.uses_mq = 		true,
- 	.icq_size =		sizeof(struct bfq_io_cq),
- 	.icq_align =		__alignof__(struct bfq_io_cq),
- 	.elevator_attrs =	bfq_attrs,
--	.elevator_name =	"bfq-sq",
-+	.elevator_name =	"bfq-mq",
- 	.elevator_owner =	THIS_MODULE,
- };
- 
-@@ -5392,7 +5454,7 @@ static int __init bfq_init(void)
- 	device_speed_thresh[0] = (4 * R_slow[0]) / 3;
- 	device_speed_thresh[1] = (4 * R_slow[1]) / 3;
- 
--	ret = elv_register(&iosched_bfq);
-+	ret = elv_register(&iosched_bfq_mq);
- 	if (ret)
- 		goto err_pol_unreg;
- 
-@@ -5412,8 +5474,8 @@ static int __init bfq_init(void)
- 
- static void __exit bfq_exit(void)
- {
--	elv_unregister(&iosched_bfq);
--#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	elv_unregister(&iosched_bfq_mq);
-+#ifdef CONFIG_BFQ_GROUP_ENABLED
- 	blkcg_policy_unregister(&blkcg_policy_bfq);
- #endif
- 	bfq_slab_kill();
-@@ -5422,5 +5484,6 @@ static void __exit bfq_exit(void)
- module_init(bfq_init);
- module_exit(bfq_exit);
- 
--MODULE_AUTHOR("Arianna Avanzini, Fabio Checconi, Paolo Valente");
-+MODULE_AUTHOR("Paolo Valente");
- MODULE_LICENSE("GPL");
-+MODULE_DESCRIPTION("MQ Budget Fair Queueing I/O Scheduler");
-diff --git a/block/bfq-mq.h b/block/bfq-mq.h
-index 0f51f270469c..c3fcd5ebd735 100644
---- a/block/bfq-mq.h
-+++ b/block/bfq-mq.h
-@@ -19,15 +19,8 @@
- #include <linux/hrtimer.h>
- #include <linux/blk-cgroup.h>
- 
--/*
-- * Define an alternative macro to compile cgroups support. This is one
-- * of the steps needed to let bfq-mq share the files bfq-sched.c and
-- * bfq-cgroup.c with bfq-sq. For bfq-mq, the macro
-- * BFQ_GROUP_IOSCHED_ENABLED will be defined as a function of whether
-- * the configuration option CONFIG_BFQ_MQ_GROUP_IOSCHED, and not
-- * CONFIG_BFQ_GROUP_IOSCHED, is defined.
-- */
--#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+/* see comments on CONFIG_BFQ_GROUP_IOSCHED in bfq.h */
-+#ifdef CONFIG_BFQ_MQ_GROUP_IOSCHED
- #define BFQ_GROUP_IOSCHED_ENABLED
- #endif
- 
-@@ -259,8 +252,8 @@ struct bfq_queue {
- 	struct request *next_rq;
- 	/* number of sync and async requests queued */
- 	int queued[2];
--	/* number of sync and async requests currently allocated */
--	int allocated[2];
-+	/* number of requests currently allocated */
-+	int allocated;
- 	/* number of pending metadata requests */
- 	int meta_pending;
- 	/* fifo list of requests in sort_list */
-@@ -345,6 +338,8 @@ struct bfq_queue {
- 	unsigned long wr_start_at_switch_to_srt;
- 
- 	unsigned long split_time; /* time of last split */
-+
-+	spinlock_t lock;
- };
- 
- /**
-@@ -361,6 +356,9 @@ struct bfq_io_cq {
- 	uint64_t blkcg_serial_nr; /* the current blkcg serial */
- #endif
- 
-+	/* delayed work to exec the body of the the exit_icq handler */
-+	struct work_struct exit_icq_work;
-+
- 	/*
- 	 * Snapshot of the has_short_time flag before merging; taken
- 	 * to remember its value while the queue is merged, so as to
-@@ -402,11 +400,13 @@ enum bfq_device_speed {
- /**
-  * struct bfq_data - per-device data structure.
-  *
-- * All the fields are protected by the @queue lock.
-+ * All the fields are protected by @lock.
-  */
- struct bfq_data {
--	/* request queue for the device */
-+	/* device request queue */
- 	struct request_queue *queue;
-+	/* dispatch queue */
-+	struct list_head dispatch;
- 
- 	/* root bfq_group for the device */
- 	struct bfq_group *root_group;
-@@ -460,8 +460,6 @@ struct bfq_data {
- 	 * the queue in service.
- 	 */
- 	struct hrtimer idle_slice_timer;
--	/* delayed work to restart dispatching on the request queue */
--	struct work_struct unplug_work;
- 
- 	/* bfq_queue in service */
- 	struct bfq_queue *in_service_queue;
-@@ -612,6 +610,8 @@ struct bfq_data {
- 
- 	/* fallback dummy bfqq for extreme OOM conditions */
- 	struct bfq_queue oom_bfqq;
-+
-+	spinlock_t lock;
- };
- 
- enum bfqq_state_flags {
-@@ -622,7 +622,6 @@ enum bfqq_state_flags {
- 					     * waiting for a request
- 					     * without idling the device
- 					     */
--	BFQ_BFQQ_FLAG_must_alloc,	/* must be allowed rq alloc */
- 	BFQ_BFQQ_FLAG_fifo_expire,	/* FIFO checked in this slice */
- 	BFQ_BFQQ_FLAG_has_short_ttime,	/* queue has a short think time */
- 	BFQ_BFQQ_FLAG_sync,		/* synchronous queue */
-@@ -661,7 +660,6 @@ BFQ_BFQQ_FNS(just_created);
- BFQ_BFQQ_FNS(busy);
- BFQ_BFQQ_FNS(wait_request);
- BFQ_BFQQ_FNS(non_blocking_wait_rq);
--BFQ_BFQQ_FNS(must_alloc);
- BFQ_BFQQ_FNS(fifo_expire);
- BFQ_BFQQ_FNS(has_short_ttime);
- BFQ_BFQQ_FNS(sync);
-@@ -692,7 +690,6 @@ static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
- #define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	do {			\
- 	char __pbuf[128];						\
- 									\
--	assert_spin_locked((bfqd)->queue->queue_lock);			\
- 	blkg_path(bfqg_to_blkg(bfqq_group(bfqq)), __pbuf, sizeof(__pbuf)); \
- 	pr_crit("%s bfq%d%c %s " fmt "\n", 				\
- 		checked_dev_name((bfqd)->queue->backing_dev_info->dev),	\
-@@ -734,7 +731,6 @@ static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
- #define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	do {			\
- 	char __pbuf[128];						\
- 									\
--	assert_spin_locked((bfqd)->queue->queue_lock);			\
- 	blkg_path(bfqg_to_blkg(bfqq_group(bfqq)), __pbuf, sizeof(__pbuf)); \
- 	blk_add_trace_msg((bfqd)->queue, "bfq%d%c %s " fmt, \
- 			  (bfqq)->pid,			  \
-@@ -961,7 +957,6 @@ static struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq)
- 
- static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio);
- static void bfq_put_queue(struct bfq_queue *bfqq);
--static void bfq_dispatch_insert(struct request_queue *q, struct request *rq);
- static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd,
- 				       struct bio *bio, bool is_sync,
- 				       struct bfq_io_cq *bic);
-
-From bde5235de2241502c1c00337bd51c96d9b60b6df Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Fri, 3 Mar 2017 08:52:40 +0100
-Subject: [PATCH 13/51] Add checks and extra log messages - Part I
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-mq-iosched.c | 112 +++++++++++++++++++++++++++++++++++++++++++++++--
- 1 file changed, 109 insertions(+), 3 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index c963d92a32c2..40eadb3f7073 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -773,6 +773,8 @@ static int bfqq_process_refs(struct bfq_queue *bfqq)
- {
- 	int process_refs, io_refs;
- 
-+	lockdep_assert_held(&bfqq->bfqd->lock);
-+
- 	io_refs = bfqq->allocated;
- 	process_refs = bfqq->ref - io_refs - bfqq->entity.on_st;
- 	BUG_ON(process_refs < 0);
-@@ -1483,6 +1485,8 @@ static void bfq_add_request(struct request *rq)
- 	bfqq->queued[rq_is_sync(rq)]++;
- 	bfqd->queued++;
- 
-+	BUG_ON(!RQ_BFQQ(rq));
-+	BUG_ON(RQ_BFQQ(rq) != bfqq);
- 	elv_rb_add(&bfqq->sort_list, rq);
- 
- 	/*
-@@ -1491,6 +1495,8 @@ static void bfq_add_request(struct request *rq)
- 	prev = bfqq->next_rq;
- 	next_rq = bfq_choose_req(bfqd, bfqq->next_rq, rq, bfqd->last_position);
- 	BUG_ON(!next_rq);
-+	BUG_ON(!RQ_BFQQ(next_rq));
-+	BUG_ON(RQ_BFQQ(next_rq) != bfqq);
- 	bfqq->next_rq = next_rq;
- 
- 	/*
-@@ -1615,6 +1621,19 @@ static void bfq_remove_request(struct request_queue *q,
- 
- 	if (bfqq->next_rq == rq) {
- 		bfqq->next_rq = bfq_find_next_rq(bfqd, bfqq, rq);
-+		if (bfqq->next_rq && !RQ_BFQQ(bfqq->next_rq)) {
-+			pr_crit("no bfqq! for next rq %p bfqq %p\n",
-+				bfqq->next_rq, bfqq);
-+		}
-+
-+		BUG_ON(bfqq->next_rq && !RQ_BFQQ(bfqq->next_rq));
-+		if (bfqq->next_rq && RQ_BFQQ(bfqq->next_rq) != bfqq) {
-+			pr_crit(
-+			"wrong bfqq! for next rq %p, rq_bfqq %p bfqq %p\n",
-+			bfqq->next_rq, RQ_BFQQ(bfqq->next_rq), bfqq);
-+		}
-+		BUG_ON(bfqq->next_rq && RQ_BFQQ(bfqq->next_rq) != bfqq);
-+
- 		bfq_updated_next_req(bfqd, bfqq);
- 	}
- 
-@@ -1701,6 +1720,8 @@ static int bfq_request_merge(struct request_queue *q, struct request **req,
- 	__rq = bfq_find_rq_fmerge(bfqd, bio, q);
- 	if (__rq && elv_bio_merge_ok(__rq, bio)) {
- 		*req = __rq;
-+		bfq_log(bfqd, "request_merge: req %p", __rq);
-+
- 		return ELEVATOR_FRONT_MERGE;
- 	}
- 
-@@ -1721,6 +1742,8 @@ static void bfq_request_merged(struct request_queue *q, struct request *req,
- 
- 		/* Reposition request in its sort_list */
- 		elv_rb_del(&bfqq->sort_list, req);
-+		BUG_ON(!RQ_BFQQ(req));
-+		BUG_ON(RQ_BFQQ(req) != bfqq);
- 		elv_rb_add(&bfqq->sort_list, req);
- 
- 		spin_lock_irq(&bfqd->lock);
-@@ -1729,7 +1752,13 @@ static void bfq_request_merged(struct request_queue *q, struct request *req,
- 		next_rq = bfq_choose_req(bfqd, bfqq->next_rq, req,
- 					 bfqd->last_position);
- 		BUG_ON(!next_rq);
-+
- 		bfqq->next_rq = next_rq;
-+
-+		bfq_log_bfqq(bfqd, bfqq,
-+			"requests_merged: req %p prev %p next_rq %p bfqq %p",
-+			     req, prev, next_rq, bfqq);
-+
- 		/*
- 		 * If next_rq changes, update both the queue's budget to
- 		 * fit the new request and the queue's position in its
-@@ -1748,8 +1777,16 @@ static void bfq_requests_merged(struct request_queue *q, struct request *rq,
- {
- 	struct bfq_queue *bfqq = RQ_BFQQ(rq), *next_bfqq = RQ_BFQQ(next);
- 
-+	BUG_ON(!RQ_BFQQ(rq));
-+	BUG_ON(!RQ_BFQQ(next));
-+
- 	if (!RB_EMPTY_NODE(&rq->rb_node))
- 		goto end;
-+
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		     "requests_merged: rq %p next %p bfqq %p next_bfqq %p",
-+		     rq, next, bfqq, next_bfqq);
-+
- 	spin_lock_irq(&bfqq->bfqd->lock);
- 
- 	/*
-@@ -3847,6 +3884,9 @@ static bool bfq_has_work(struct blk_mq_hw_ctx *hctx)
- {
- 	struct bfq_data *bfqd = hctx->queue->elevator->elevator_data;
- 
-+	bfq_log(bfqd, "has_work, dispatch_non_empty %d busy_queues %d",
-+		!list_empty_careful(&bfqd->dispatch), bfqd->busy_queues > 0);
-+
- 	/*
- 	 * Avoiding lock: a race on bfqd->busy_queues should cause at
- 	 * most a call to dispatch for nothing
-@@ -3865,6 +3905,8 @@ static struct request *__bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
- 		rq = list_first_entry(&bfqd->dispatch, struct request,
- 				      queuelist);
- 		list_del_init(&rq->queuelist);
-+		bfq_log(bfqd,
-+			"dispatch requests: picked %p from dispatch list", rq);
- 		goto exit;
- 	}
- 
-@@ -3904,7 +3946,20 @@ static struct request *__bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
- 	if (rq) {
- 		rq->rq_flags |= RQF_STARTED;
- 		bfqd->rq_in_driver++;
--	}
-+		if (bfqq)
-+			bfq_log_bfqq(bfqd, bfqq,
-+				"dispatched %s request %p, rq_in_driver %d",
-+				     bfq_bfqq_sync(bfqq) ? "sync" : "async",
-+				     rq,
-+				     bfqd->rq_in_driver);
-+		else
-+			bfq_log(bfqd,
-+		"dispatched request %p from dispatch list, rq_in_driver %d",
-+				rq, bfqd->rq_in_driver);
-+	} else
-+		bfq_log(bfqd,
-+		"returned NULL request, rq_in_driver %d",
-+			bfqd->rq_in_driver);
- 
- 	return rq;
- }
-@@ -3944,6 +3999,7 @@ static void bfq_put_queue(struct bfq_queue *bfqq)
- 		return;
- 
- 	BUG_ON(rb_first(&bfqq->sort_list));
-+	BUG_ON(bfqq->allocated != 0);
- 	BUG_ON(bfqq->entity.tree);
- 	BUG_ON(bfq_bfqq_busy(bfqq));
- 
-@@ -4043,6 +4099,7 @@ static void bfq_exit_icq(struct io_cq *icq)
- {
- 	struct bfq_io_cq *bic = icq_to_bic(icq);
- 
-+	BUG_ON(!bic);
- 	kblockd_schedule_work(&bic->exit_icq_work);
- }
- 
-@@ -4057,6 +4114,7 @@ static void bfq_set_next_ioprio_data(struct bfq_queue *bfqq,
- 	int ioprio_class;
- 	struct bfq_data *bfqd = bfqq->bfqd;
- 
-+	WARN_ON(!bfqd);
- 	if (!bfqd)
- 		return;
- 
-@@ -4404,6 +4462,10 @@ static void __bfq_insert_request(struct bfq_data *bfqd, struct request *rq)
- {
- 	struct bfq_queue *bfqq = RQ_BFQQ(rq), *new_bfqq;
- 
-+	assert_spin_locked(&bfqd->lock);
-+
-+	bfq_log_bfqq(bfqd, bfqq, "__insert_req: rq %p bfqq %p", rq, bfqq);
-+
- 	/*
- 	 * An unplug may trigger a requeue of a request from the device
- 	 * driver: make sure we are in process context while trying to
-@@ -4420,6 +4482,12 @@ static void __bfq_insert_request(struct bfq_data *bfqd, struct request *rq)
- 			 */
- 			new_bfqq->allocated++;
- 			bfqq->allocated--;
-+			bfq_log_bfqq(bfqd, bfqq,
-+		     "insert_request: new allocated %d", bfqq->allocated);
-+			bfq_log_bfqq(bfqd, new_bfqq,
-+		     "insert_request: new_bfqq new allocated %d",
-+				     bfqq->allocated);
-+
- 			new_bfqq->ref++;
- 			bfq_clear_bfqq_just_created(bfqq);
- 			if (bic_to_bfqq(RQ_BIC(rq), 1) == bfqq)
-@@ -4529,6 +4597,10 @@ static void bfq_completed_request(struct bfq_queue *bfqq, struct bfq_data *bfqd)
- 	bfqd->rq_in_driver--;
- 	bfqq->dispatched--;
- 
-+	bfq_log_bfqq(bfqd, bfqq,
-+		     "completed_requests: new disp %d, new rq_in_driver %d",
-+		     bfqq->dispatched, bfqd->rq_in_driver);
-+
- 	if (!bfqq->dispatched && !bfq_bfqq_busy(bfqq)) {
- 		BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list));
- 		/*
-@@ -4618,6 +4690,9 @@ static void bfq_completed_request(struct bfq_queue *bfqq, struct bfq_data *bfqd)
- 
- static void bfq_put_rq_priv_body(struct bfq_queue *bfqq)
- {
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		     "put_request_body: allocated %d", bfqq->allocated);
-+	BUG_ON(!bfqq->allocated);
- 	bfqq->allocated--;
- 
- 	bfq_put_queue(bfqq);
-@@ -4625,8 +4700,27 @@ static void bfq_put_rq_priv_body(struct bfq_queue *bfqq)
- 
- static void bfq_put_rq_private(struct request_queue *q, struct request *rq)
- {
--	struct bfq_queue *bfqq = RQ_BFQQ(rq);
--	struct bfq_data *bfqd = bfqq->bfqd;
-+	struct bfq_queue *bfqq;
-+	struct bfq_data *bfqd;
-+	struct bfq_io_cq *bic;
-+
-+	BUG_ON(!rq);
-+	bfqq = RQ_BFQQ(rq);
-+	BUG_ON(!bfqq);
-+
-+	bic = RQ_BIC(rq);
-+	BUG_ON(!bic);
-+
-+	bfqd = bfqq->bfqd;
-+	BUG_ON(!bfqd);
-+
-+	BUG_ON(rq->rq_flags & RQF_QUEUED);
-+	BUG_ON(!(rq->rq_flags & RQF_ELVPRIV));
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+		     "putting rq %p with %u sects left, STARTED %d",
-+		     rq, blk_rq_sectors(rq),
-+		     rq->rq_flags & RQF_STARTED);
- 
- 	if (rq->rq_flags & RQF_STARTED)
- 		bfqg_stats_update_completion(bfqq_group(bfqq),
-@@ -4634,6 +4728,8 @@ static void bfq_put_rq_private(struct request_queue *q, struct request *rq)
- 					     rq_io_start_time_ns(rq),
- 					     rq->cmd_flags);
- 
-+	BUG_ON(blk_rq_sectors(rq) == 0 && !(rq->rq_flags & RQF_STARTED));
-+
- 	if (likely(rq->rq_flags & RQF_STARTED)) {
- 		unsigned long flags;
- 
-@@ -4655,7 +4751,9 @@ static void bfq_put_rq_private(struct request_queue *q, struct request *rq)
- 		 * cause any deadlock, even if other locks are already
- 		 * (correctly) held by this process.
- 		 */
-+		BUG_ON(in_interrupt());
- 
-+		assert_spin_locked(&bfqd->lock);
- 		if (!RB_EMPTY_NODE(&rq->rb_node))
- 			bfq_remove_request(q, rq);
- 		bfq_put_rq_priv_body(bfqq);
-@@ -4814,7 +4912,9 @@ static void bfq_idle_slice_timer_body(struct bfq_queue *bfqq)
- 	enum bfqq_expiration reason;
- 	unsigned long flags;
- 
-+	BUG_ON(!bfqd);
- 	spin_lock_irqsave(&bfqd->lock, flags);
-+	bfq_log_bfqq(bfqd, bfqq, "handling slice_timer expiration");
- 	bfq_clear_bfqq_wait_request(bfqq);
- 
- 	if (bfqq != bfqd->in_service_queue) {
-@@ -4857,6 +4957,8 @@ static enum hrtimer_restart bfq_idle_slice_timer(struct hrtimer *timer)
- 					     idle_slice_timer);
- 	struct bfq_queue *bfqq = bfqd->in_service_queue;
- 
-+	bfq_log(bfqd, "slice_timer expired");
-+
- 	/*
- 	 * Theoretical race here: the in-service queue can be NULL or
- 	 * different from the queue that was idling if a new request
-@@ -4909,9 +5011,12 @@ static void bfq_exit_queue(struct elevator_queue *e)
- 	struct bfq_data *bfqd = e->elevator_data;
- 	struct bfq_queue *bfqq, *n;
- 
-+	bfq_log(bfqd, "exit_queue: starting ...");
-+
- 	hrtimer_cancel(&bfqd->idle_slice_timer);
- 
- 	BUG_ON(bfqd->in_service_queue);
-+	BUG_ON(!list_empty(&bfqd->active_list));
- 
- 	list_for_each_entry_safe(bfqq, n, &bfqd->idle_list, bfqq_list) {
- 		if (bfqq->bic) /* bfqqs without bic are handled below */
-@@ -4943,6 +5048,7 @@ static void bfq_exit_queue(struct elevator_queue *e)
- 	spin_unlock_irq(&bfqd->lock);
- #endif
- 
-+	bfq_log(bfqd, "exit_queue: finished ...");
- 	kfree(bfqd);
- }
- 
-
-From 7f59486861e368d25f59d4136cf8e51a75b7edf9 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Thu, 9 Feb 2017 10:36:27 +0100
-Subject: [PATCH 14/51] Add lock check in bfq_allow_bio_merge
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-mq-iosched.c | 1 +
- 1 file changed, 1 insertion(+)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 40eadb3f7073..21b876aeba16 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -2279,6 +2279,7 @@ static bool bfq_allow_bio_merge(struct request_queue *q, struct request *rq,
- 	if (!bic)
- 		return false;
- 
-+	assert_spin_locked(&bfqd->lock);
- 	bfqq = bic_to_bfqq(bic, is_sync);
- 	/*
- 	 * We take advantage of this function to perform an early merge
-
-From a2dd19a4d95cf401268c144c79ce549c7fc4bbca Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Tue, 7 Feb 2017 15:14:29 +0100
-Subject: [PATCH 15/51] bfq-mq: execute exit_icq operations immediately
-
-Exploting Omar's patch that removes the taking of the queue lock in
-put_io_context_active, this patch moves back the operation of the bfq_exit_icq
-hook from a deferred work to the body of the function.
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-mq-iosched.c | 34 +++-------------------------------
- block/bfq-mq.h         |  3 ---
- 2 files changed, 3 insertions(+), 34 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 21b876aeba16..1deb79a47181 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -4080,28 +4080,13 @@ static void bfq_exit_icq_bfqq(struct bfq_io_cq *bic, bool is_sync)
- 	}
- }
- 
--static void bfq_exit_icq_body(struct work_struct *work)
--{
--	struct bfq_io_cq *bic =
--		container_of(work, struct bfq_io_cq, exit_icq_work);
--
--	bfq_exit_icq_bfqq(bic, true);
--	bfq_exit_icq_bfqq(bic, false);
--}
--
--static void bfq_init_icq(struct io_cq *icq)
--{
--	struct bfq_io_cq *bic = icq_to_bic(icq);
--
--	INIT_WORK(&bic->exit_icq_work, bfq_exit_icq_body);
--}
--
- static void bfq_exit_icq(struct io_cq *icq)
- {
- 	struct bfq_io_cq *bic = icq_to_bic(icq);
- 
- 	BUG_ON(!bic);
--	kblockd_schedule_work(&bic->exit_icq_work);
-+	bfq_exit_icq_bfqq(bic, true);
-+	bfq_exit_icq_bfqq(bic, false);
- }
- 
- /*
-@@ -5019,21 +5004,9 @@ static void bfq_exit_queue(struct elevator_queue *e)
- 	BUG_ON(bfqd->in_service_queue);
- 	BUG_ON(!list_empty(&bfqd->active_list));
- 
--	list_for_each_entry_safe(bfqq, n, &bfqd->idle_list, bfqq_list) {
--		if (bfqq->bic) /* bfqqs without bic are handled below */
--			cancel_work_sync(&bfqq->bic->exit_icq_work);
--	}
--
- 	spin_lock_irq(&bfqd->lock);
--	list_for_each_entry_safe(bfqq, n, &bfqd->idle_list, bfqq_list) {
-+	list_for_each_entry_safe(bfqq, n, &bfqd->idle_list, bfqq_list)
- 		bfq_deactivate_bfqq(bfqd, bfqq, false, false);
--		/*
--		 * Make sure that deferred exit_icq_work completes
--		 * without errors for bfq_queues without bic
--		 */
--		if (!bfqq->bic)
--			bfqq->bfqd = NULL;
--	}
- 	spin_unlock_irq(&bfqd->lock);
- 
- 	hrtimer_cancel(&bfqd->idle_slice_timer);
-@@ -5471,7 +5444,6 @@ static struct elevator_type iosched_bfq_mq = {
- 	.ops.mq = {
- 		.get_rq_priv		= bfq_get_rq_private,
- 		.put_rq_priv		= bfq_put_rq_private,
--		.init_icq		= bfq_init_icq,
- 		.exit_icq		= bfq_exit_icq,
- 		.insert_requests	= bfq_insert_requests,
- 		.dispatch_request	= bfq_dispatch_request,
-diff --git a/block/bfq-mq.h b/block/bfq-mq.h
-index c3fcd5ebd735..23744b246db6 100644
---- a/block/bfq-mq.h
-+++ b/block/bfq-mq.h
-@@ -356,9 +356,6 @@ struct bfq_io_cq {
- 	uint64_t blkcg_serial_nr; /* the current blkcg serial */
- #endif
- 
--	/* delayed work to exec the body of the the exit_icq handler */
--	struct work_struct exit_icq_work;
--
- 	/*
- 	 * Snapshot of the has_short_time flag before merging; taken
- 	 * to remember its value while the queue is merged, so as to
-
-From ab7e78a0ff095101de74e700f8743295a500bb20 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Tue, 21 Feb 2017 10:26:22 +0100
-Subject: [PATCH 16/51] Unnest request-queue and ioc locks from scheduler locks
-
-In some bio-merging functions, the request-queue lock needs to be
-taken, to lookup for the bic associated with the process that issued
-the bio that may need to be merged. In addition, put_io_context must
-be invoked in some other functions, and put_io_context may cause the
-lock of the involved ioc to be taken. In both cases, these extra
-request-queue or ioc locks are taken, or might be taken, while the
-scheduler lock is being held. In this respect, there are other code
-paths, in part external to bfq-mq, in which the same locks are taken
-(nested) in the opposite order, i.e., it is the scheduler lock to be
-taken while the request-queue or the ioc lock is being held.  This
-leads to circular deadlocks.
-
-This commit addresses this issue by modifying the logic of the above
-functions, so as to let the lookup and put_io_context be performed,
-and thus the extra locks be taken, outside the critical sections
-protected by the scheduler lock.
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-cgroup-included.c |   9 ++
- block/bfq-mq-iosched.c      | 264 ++++++++++++++++++++++++++++----------------
- block/bfq-mq.h              |  25 ++++-
- block/bfq-sched.c           |  11 ++
- 4 files changed, 213 insertions(+), 96 deletions(-)
-
-diff --git a/block/bfq-cgroup-included.c b/block/bfq-cgroup-included.c
-index 8a73de76f32b..cf59eeb7f08e 100644
---- a/block/bfq-cgroup-included.c
-+++ b/block/bfq-cgroup-included.c
-@@ -716,6 +716,9 @@ static void bfq_pd_offline(struct blkg_policy_data *pd)
- 	struct bfq_group *bfqg;
- 	struct bfq_data *bfqd;
- 	struct bfq_entity *entity;
-+#ifdef BFQ_MQ
-+	unsigned long flags;
-+#endif
- 	int i;
- 
- 	BUG_ON(!pd);
-@@ -729,6 +732,9 @@ static void bfq_pd_offline(struct blkg_policy_data *pd)
- 	if (!entity) /* root group */
- 		return;
- 
-+#ifdef BFQ_MQ
-+	spin_lock_irqsave(&bfqd->lock, flags);
-+#endif
- 	/*
- 	 * Empty all service_trees belonging to this group before
- 	 * deactivating the group itself.
-@@ -766,6 +772,9 @@ static void bfq_pd_offline(struct blkg_policy_data *pd)
- 	__bfq_deactivate_entity(entity, false);
- 	bfq_put_async_queues(bfqd, bfqg);
- 
-+#ifdef BFQ_MQ
-+	bfq_unlock_put_ioc_restore(bfqd, flags);
-+#endif
- 	/*
- 	 * @blkg is going offline and will be ignored by
- 	 * blkg_[rw]stat_recursive_sum().  Transfer stats to the parent so
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 1deb79a47181..69ef3761c95d 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -233,6 +233,7 @@ static struct bfq_io_cq *bfq_bic_lookup(struct bfq_data *bfqd,
- 	return NULL;
- }
- 
-+#define BFQ_MQ
- #include "bfq-sched.c"
- #include "bfq-cgroup-included.c"
- 
-@@ -1564,15 +1565,9 @@ static struct request *bfq_find_rq_fmerge(struct bfq_data *bfqd,
- 					  struct bio *bio,
- 					  struct request_queue *q)
- {
--	struct task_struct *tsk = current;
--	struct bfq_io_cq *bic;
--	struct bfq_queue *bfqq;
-+	struct bfq_queue *bfqq = bfqd->bio_bfqq;
- 
--	bic = bfq_bic_lookup(bfqd, tsk->io_context, q);
--	if (!bic)
--		return NULL;
- 
--	bfqq = bic_to_bfqq(bic, op_is_sync(bio->bi_opf));
- 	if (bfqq)
- 		return elv_rb_find(&bfqq->sort_list, bio_end_sector(bio));
- 
-@@ -1693,9 +1688,26 @@ static bool bfq_bio_merge(struct blk_mq_hw_ctx *hctx, struct bio *bio)
- 	struct request_queue *q = hctx->queue;
- 	struct bfq_data *bfqd = q->elevator->elevator_data;
- 	struct request *free = NULL;
-+	/*
-+	 * bfq_bic_lookup grabs the queue_lock: invoke it now and
-+	 * store its return value for later use, to avoid nesting
-+	 * queue_lock inside the bfqd->lock. We assume that the bic
-+	 * returned by bfq_bic_lookup does not go away before
-+	 * bfqd->lock is taken.
-+	 */
-+	struct bfq_io_cq *bic = bfq_bic_lookup(bfqd, current->io_context, q);
- 	bool ret;
- 
- 	spin_lock_irq(&bfqd->lock);
-+
-+	if (bic)
-+		bfqd->bio_bfqq = bic_to_bfqq(bic, op_is_sync(bio->bi_opf));
-+	else
-+		bfqd->bio_bfqq = NULL;
-+	bfqd->bio_bic = bic;
-+	/* Set next flag just for testing purposes */
-+	bfqd->bio_bfqq_set = true;
-+
- 	ret = blk_mq_sched_try_merge(q, bio, &free);
- 
- 	/*
-@@ -1706,6 +1718,7 @@ static bool bfq_bio_merge(struct blk_mq_hw_ctx *hctx, struct bio *bio)
- 	 */
- 	if (free)
- 		blk_mq_free_request(free);
-+	bfqd->bio_bfqq_set = false;
- 	spin_unlock_irq(&bfqd->lock);
- 
- 	return ret;
-@@ -2261,8 +2274,7 @@ static bool bfq_allow_bio_merge(struct request_queue *q, struct request *rq,
- {
- 	struct bfq_data *bfqd = q->elevator->elevator_data;
- 	bool is_sync = op_is_sync(bio->bi_opf);
--	struct bfq_io_cq *bic;
--	struct bfq_queue *bfqq, *new_bfqq;
-+	struct bfq_queue *bfqq = bfqd->bio_bfqq, *new_bfqq;
- 
- 	/*
- 	 * Disallow merge of a sync bio into an async request.
-@@ -2273,31 +2285,40 @@ static bool bfq_allow_bio_merge(struct request_queue *q, struct request *rq,
- 	/*
- 	 * Lookup the bfqq that this bio will be queued with. Allow
- 	 * merge only if rq is queued there.
--	 * Queue lock is held here.
- 	 */
--	bic = bfq_bic_lookup(bfqd, current->io_context, q);
--	if (!bic)
-+	if (!bfqq)
- 		return false;
- 
--	assert_spin_locked(&bfqd->lock);
--	bfqq = bic_to_bfqq(bic, is_sync);
- 	/*
- 	 * We take advantage of this function to perform an early merge
- 	 * of the queues of possible cooperating processes.
- 	 */
--	if (bfqq) {
--		new_bfqq = bfq_setup_cooperator(bfqd, bfqq, bio, false);
--		if (new_bfqq) {
--			bfq_merge_bfqqs(bfqd, bic, bfqq, new_bfqq);
--			/*
--			 * If we get here, the bio will be queued in the
--			 * shared queue, i.e., new_bfqq, so use new_bfqq
--			 * to decide whether bio and rq can be merged.
--			 */
--			bfqq = new_bfqq;
--		}
--	}
-+	new_bfqq = bfq_setup_cooperator(bfqd, bfqq, bio, false);
-+	if (new_bfqq) {
-+		/*
-+		 * bic still points to bfqq, then it has not yet been
-+		 * redirected to some other bfq_queue, and a queue
-+		 * merge beween bfqq and new_bfqq can be safely
-+		 * fulfillled, i.e., bic can be redirected to new_bfqq
-+		 * and bfqq can be put.
-+		 */
-+		bfq_merge_bfqqs(bfqd, bfqd->bio_bic, bfqq,
-+				new_bfqq);
-+		/*
-+		 * If we get here, bio will be queued into new_queue,
-+		 * so use new_bfqq to decide whether bio and rq can be
-+		 * merged.
-+		 */
-+		bfqq = new_bfqq;
- 
-+		/*
-+		 * Change also bqfd->bio_bfqq, as
-+		 * bfqd->bio_bic now points to new_bfqq, and
-+		 * this function may be invoked again (and then may
-+		 * use again bqfd->bio_bfqq).
-+		 */
-+		bfqd->bio_bfqq = bfqq;
-+	}
- 	return bfqq == RQ_BFQQ(rq);
- }
- 
-@@ -3965,14 +3986,43 @@ static struct request *__bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
- 	return rq;
- }
- 
-+/*
-+ * Next two functions release bfqd->lock and put the io context
-+ * pointed by bfqd->ioc_to_put. This delayed put is used to not risk
-+ * to take an ioc->lock while the scheduler lock is being held.
-+ */
-+static void bfq_unlock_put_ioc(struct bfq_data *bfqd)
-+{
-+	struct io_context *ioc_to_put = bfqd->ioc_to_put;
-+
-+	bfqd->ioc_to_put = NULL;
-+	spin_unlock_irq(&bfqd->lock);
-+
-+	if (ioc_to_put)
-+		put_io_context(ioc_to_put);
-+}
-+
-+static void bfq_unlock_put_ioc_restore(struct bfq_data *bfqd,
-+				       unsigned long flags)
-+{
-+	struct io_context *ioc_to_put = bfqd->ioc_to_put;
-+
-+	bfqd->ioc_to_put = NULL;
-+	spin_unlock_irqrestore(&bfqd->lock, flags);
-+
-+	if (ioc_to_put)
-+		put_io_context(ioc_to_put);
-+}
-+
- static struct request *bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
- {
- 	struct bfq_data *bfqd = hctx->queue->elevator->elevator_data;
- 	struct request *rq;
- 
- 	spin_lock_irq(&bfqd->lock);
-+
- 	rq = __bfq_dispatch_request(hctx);
--	spin_unlock_irq(&bfqd->lock);
-+	bfq_unlock_put_ioc(bfqd);
- 
- 	return rq;
- }
-@@ -3981,7 +4031,7 @@ static struct request *bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
-  * Task holds one reference to the queue, dropped when task exits.  Each rq
-  * in-flight on this queue also holds a reference, dropped when rq is freed.
-  *
-- * Queue lock must be held here. Recall not to use bfqq after calling
-+ * Scheduler lock must be held here. Recall not to use bfqq after calling
-  * this function on it.
-  */
- static void bfq_put_queue(struct bfq_queue *bfqq)
-@@ -4066,17 +4116,23 @@ static void bfq_exit_icq_bfqq(struct bfq_io_cq *bic, bool is_sync)
- 		bfqd = bfqq->bfqd; /* NULL if scheduler already exited */
- 
- 	if (bfqq && bfqd) {
--		spin_lock_irq(&bfqd->lock);
-+		unsigned long flags;
-+
-+		spin_lock_irqsave(&bfqd->lock, flags);
- 		/*
--		 * If the bic is using a shared queue, put the reference
--		 * taken on the io_context when the bic started using a
--		 * shared bfq_queue.
-+		 * If the bic is using a shared queue, put the
-+		 * reference taken on the io_context when the bic
-+		 * started using a shared bfq_queue. This put cannot
-+		 * make ioc->ref_count reach 0, then no ioc->lock
-+		 * risks to be taken (leading to possible deadlock
-+		 * scenarios).
- 		 */
- 		if (is_sync && bfq_bfqq_coop(bfqq))
- 			put_io_context(bic->icq.ioc);
-+
- 		bfq_exit_bfqq(bfqd, bfqq);
- 		bic_set_bfqq(bic, NULL, is_sync);
--		spin_unlock_irq(&bfqd->lock);
-+		bfq_unlock_put_ioc_restore(bfqd, flags);
- 	}
- }
- 
-@@ -4183,8 +4239,6 @@ static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 	INIT_HLIST_NODE(&bfqq->burst_list_node);
- 	BUG_ON(!hlist_unhashed(&bfqq->burst_list_node));
- 
--	spin_lock_init(&bfqq->lock);
--
- 	bfqq->ref = 0;
- 	bfqq->bfqd = bfqd;
- 
-@@ -4476,6 +4530,14 @@ static void __bfq_insert_request(struct bfq_data *bfqd, struct request *rq)
- 
- 			new_bfqq->ref++;
- 			bfq_clear_bfqq_just_created(bfqq);
-+			/*
-+			 * If the bic associated with the process
-+			 * issuing this request still points to bfqq
-+			 * (and thus has not been already redirected
-+			 * to new_bfqq or even some other bfq_queue),
-+			 * then complete the merge and redirect it to
-+			 * new_bfqq.
-+			 */
- 			if (bic_to_bfqq(RQ_BIC(rq), 1) == bfqq)
- 				bfq_merge_bfqqs(bfqd, RQ_BIC(rq),
- 						bfqq, new_bfqq);
-@@ -4498,14 +4560,17 @@ static void __bfq_insert_request(struct bfq_data *bfqd, struct request *rq)
- }
- 
- static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
--			      bool at_head)
-+			       bool at_head)
- {
- 	struct request_queue *q = hctx->queue;
- 	struct bfq_data *bfqd = q->elevator->elevator_data;
- 
- 	spin_lock_irq(&bfqd->lock);
--	if (blk_mq_sched_try_insert_merge(q, rq))
--		goto done;
-+	if (blk_mq_sched_try_insert_merge(q, rq)) {
-+		spin_unlock_irq(&bfqd->lock);
-+		return;
-+	}
-+
- 	spin_unlock_irq(&bfqd->lock);
- 
- 	blk_mq_sched_request_inserted(rq);
-@@ -4530,8 +4595,8 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
- 				q->last_merge = rq;
- 		}
- 	}
--done:
--	spin_unlock_irq(&bfqd->lock);
-+
-+	bfq_unlock_put_ioc(bfqd);
- }
- 
- static void bfq_insert_requests(struct blk_mq_hw_ctx *hctx,
-@@ -4724,7 +4789,7 @@ static void bfq_put_rq_private(struct request_queue *q, struct request *rq)
- 		bfq_completed_request(bfqq, bfqd);
- 		bfq_put_rq_priv_body(bfqq);
- 
--		spin_unlock_irqrestore(&bfqd->lock, flags);
-+		bfq_unlock_put_ioc_restore(bfqd, flags);
- 	} else {
- 		/*
- 		 * Request rq may be still/already in the scheduler,
-@@ -4732,10 +4797,10 @@ static void bfq_put_rq_private(struct request_queue *q, struct request *rq)
- 		 * defer such a check and removal, to avoid
- 		 * inconsistencies in the time interval from the end
- 		 * of this function to the start of the deferred work.
--		 * Fortunately, this situation occurs only in process
--		 * context, so taking the scheduler lock does not
--		 * cause any deadlock, even if other locks are already
--		 * (correctly) held by this process.
-+		 * This situation seems to occur only in process
-+		 * context, as a consequence of a merge. In the
-+		 * current version of the code, this implies that the
-+		 * lock is held.
- 		 */
- 		BUG_ON(in_interrupt());
- 
-@@ -4758,8 +4823,6 @@ bfq_split_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq)
- {
- 	bfq_log_bfqq(bfqq->bfqd, bfqq, "splitting queue");
- 
--	put_io_context(bic->icq.ioc);
--
- 	if (bfqq_process_refs(bfqq) == 1) {
- 		bfqq->pid = current->pid;
- 		bfq_clear_bfqq_coop(bfqq);
-@@ -4775,6 +4838,41 @@ bfq_split_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq)
- 	return NULL;
- }
- 
-+static struct bfq_queue *bfq_get_bfqq_handle_split(struct bfq_data *bfqd,
-+						   struct bfq_io_cq *bic,
-+						   struct bio *bio,
-+						   bool split, bool is_sync,
-+						   bool *new_queue)
-+{
-+	struct bfq_queue *bfqq = bic_to_bfqq(bic, is_sync);
-+
-+	if (likely(bfqq && bfqq != &bfqd->oom_bfqq))
-+		return bfqq;
-+
-+	if (new_queue)
-+		*new_queue = true;
-+
-+	if (bfqq)
-+		bfq_put_queue(bfqq);
-+	bfqq = bfq_get_queue(bfqd, bio, is_sync, bic);
-+
-+	bic_set_bfqq(bic, bfqq, is_sync);
-+	if (split && is_sync) {
-+		if ((bic->was_in_burst_list && bfqd->large_burst) ||
-+		    bic->saved_in_large_burst)
-+			bfq_mark_bfqq_in_large_burst(bfqq);
-+		else {
-+			bfq_clear_bfqq_in_large_burst(bfqq);
-+			if (bic->was_in_burst_list)
-+				hlist_add_head(&bfqq->burst_list_node,
-+					       &bfqd->burst_list);
-+		}
-+		bfqq->split_time = jiffies;
-+	}
-+
-+	return bfqq;
-+}
-+
- /*
-  * Allocate bfq data structures associated with this request.
-  */
-@@ -4786,6 +4884,7 @@ static int bfq_get_rq_private(struct request_queue *q, struct request *rq,
- 	const int is_sync = rq_is_sync(rq);
- 	struct bfq_queue *bfqq;
- 	bool bfqq_already_existing = false, split = false;
-+	bool new_queue = false;
- 
- 	spin_lock_irq(&bfqd->lock);
- 
-@@ -4796,42 +4895,10 @@ static int bfq_get_rq_private(struct request_queue *q, struct request *rq,
- 
- 	bfq_bic_update_cgroup(bic, bio);
- 
--new_queue:
--	bfqq = bic_to_bfqq(bic, is_sync);
--	if (!bfqq || bfqq == &bfqd->oom_bfqq) {
--		if (bfqq)
--			bfq_put_queue(bfqq);
--		bfqq = bfq_get_queue(bfqd, bio, is_sync, bic);
--		BUG_ON(!hlist_unhashed(&bfqq->burst_list_node));
-+	bfqq = bfq_get_bfqq_handle_split(bfqd, bic, bio, false, is_sync,
-+					 &new_queue);
- 
--		bic_set_bfqq(bic, bfqq, is_sync);
--		if (split && is_sync) {
--			bfq_log_bfqq(bfqd, bfqq,
--				     "get_request: was_in_list %d "
--				     "was_in_large_burst %d "
--				     "large burst in progress %d",
--				     bic->was_in_burst_list,
--				     bic->saved_in_large_burst,
--				     bfqd->large_burst);
--
--			if ((bic->was_in_burst_list && bfqd->large_burst) ||
--			    bic->saved_in_large_burst) {
--				bfq_log_bfqq(bfqd, bfqq,
--					     "get_request: marking in "
--					     "large burst");
--				bfq_mark_bfqq_in_large_burst(bfqq);
--			} else {
--				bfq_log_bfqq(bfqd, bfqq,
--					     "get_request: clearing in "
--					     "large burst");
--				bfq_clear_bfqq_in_large_burst(bfqq);
--				if (bic->was_in_burst_list)
--					hlist_add_head(&bfqq->burst_list_node,
--						       &bfqd->burst_list);
--			}
--			bfqq->split_time = jiffies;
--		}
--	} else {
-+	if (unlikely(!new_queue)) {
- 		/* If the queue was seeky for too long, break it apart. */
- 		if (bfq_bfqq_coop(bfqq) && bfq_bfqq_split_coop(bfqq)) {
- 			bfq_log_bfqq(bfqd, bfqq, "breaking apart bfqq");
-@@ -4841,9 +4908,19 @@ static int bfq_get_rq_private(struct request_queue *q, struct request *rq,
- 				bic->saved_in_large_burst = true;
- 
- 			bfqq = bfq_split_bfqq(bic, bfqq);
--			split = true;
-+			/*
-+			 * A reference to bic->icq.ioc needs to be
-+			 * released after a queue split. Do not do it
-+			 * immediately, to not risk to possibly take
-+			 * an ioc->lock while holding the scheduler
-+			 * lock.
-+			 */
-+			bfqd->ioc_to_put = bic->icq.ioc;
-+
- 			if (!bfqq)
--				goto new_queue;
-+				bfqq = bfq_get_bfqq_handle_split(bfqd, bic, bio,
-+								 true, is_sync,
-+								 NULL);
- 			else
- 				bfqq_already_existing = true;
- 		}
-@@ -4861,18 +4938,17 @@ static int bfq_get_rq_private(struct request_queue *q, struct request *rq,
- 
- 	/*
- 	 * If a bfq_queue has only one process reference, it is owned
--	 * by only one bfq_io_cq: we can set the bic field of the
--	 * bfq_queue to the address of that structure. Also, if the
--	 * queue has just been split, mark a flag so that the
--	 * information is available to the other scheduler hooks.
-+	 * by only this bic: we can then set bfqq->bic = bic. in
-+	 * addition, if the queue has also just been split, we have to
-+	 * resume its state.
- 	 */
- 	if (likely(bfqq != &bfqd->oom_bfqq) && bfqq_process_refs(bfqq) == 1) {
- 		bfqq->bic = bic;
--		if (split) {
-+		if (bfqd->ioc_to_put) { /* if true, then there has been a split */
- 			/*
--			 * If the queue has just been split from a shared
--			 * queue, restore the idle window and the possible
--			 * weight raising period.
-+			 * The queue has just been split from a shared
-+			 * queue: restore the idle window and the
-+			 * possible weight raising period.
- 			 */
- 			bfq_bfqq_resume_state(bfqq, bfqd, bic,
- 					      bfqq_already_existing);
-@@ -4882,7 +4958,7 @@ static int bfq_get_rq_private(struct request_queue *q, struct request *rq,
- 	if (unlikely(bfq_bfqq_just_created(bfqq)))
- 		bfq_handle_burst(bfqd, bfqq);
- 
--	spin_unlock_irq(&bfqd->lock);
-+	bfq_unlock_put_ioc(bfqd);
- 
- 	return 0;
- 
-@@ -4929,7 +5005,7 @@ static void bfq_idle_slice_timer_body(struct bfq_queue *bfqq)
- 	bfq_bfqq_expire(bfqd, bfqq, true, reason);
- 
- schedule_dispatch:
--	spin_unlock_irqrestore(&bfqd->lock, flags);
-+	bfq_unlock_put_ioc_restore(bfqd, flags);
- 	bfq_schedule_dispatch(bfqd);
- }
- 
-diff --git a/block/bfq-mq.h b/block/bfq-mq.h
-index 23744b246db6..bd83f1c02573 100644
---- a/block/bfq-mq.h
-+++ b/block/bfq-mq.h
-@@ -338,8 +338,6 @@ struct bfq_queue {
- 	unsigned long wr_start_at_switch_to_srt;
- 
- 	unsigned long split_time; /* time of last split */
--
--	spinlock_t lock;
- };
- 
- /**
-@@ -609,6 +607,29 @@ struct bfq_data {
- 	struct bfq_queue oom_bfqq;
- 
- 	spinlock_t lock;
-+
-+	/*
-+	 * bic associated with the task issuing current bio for
-+	 * merging. This and the next field are used as a support to
-+	 * be able to perform the bic lookup, needed by bio-merge
-+	 * functions, before the scheduler lock is taken, and thus
-+	 * avoid taking the request-queue lock while the scheduler
-+	 * lock is being held.
-+	 */
-+	struct bfq_io_cq *bio_bic;
-+	/* bfqq associated with the task issuing current bio for merging */
-+	struct bfq_queue *bio_bfqq;
-+	/* Extra flag used only for TESTING */
-+	bool bio_bfqq_set;
-+
-+	/*
-+	 * io context to put right after bfqd->lock is released. This
-+	 * filed is used to perform put_io_context, when needed, to
-+	 * after the scheduler lock has been released, and thus
-+	 * prevent an ioc->lock from being possibly taken while the
-+	 * scheduler lock is being held.
-+	 */
-+	struct io_context *ioc_to_put;
- };
- 
- enum bfqq_state_flags {
-diff --git a/block/bfq-sched.c b/block/bfq-sched.c
-index b54a638186e3..a5c8b4acd33c 100644
---- a/block/bfq-sched.c
-+++ b/block/bfq-sched.c
-@@ -1905,7 +1905,18 @@ static void __bfq_bfqd_reset_in_service(struct bfq_data *bfqd)
- 	struct bfq_entity *entity = in_serv_entity;
- 
- 	if (bfqd->in_service_bic) {
-+#ifdef BFQ_MQ
-+		/*
-+		 * Schedule the release of a reference to
-+		 * bfqd->in_service_bic->icq.ioc to right after the
-+		 * scheduler lock is released. This ioc is not
-+		 * released immediately, to not risk to possibly take
-+		 * an ioc->lock while holding the scheduler lock.
-+		 */
-+		bfqd->ioc_to_put = bfqd->in_service_bic->icq.ioc;
-+#else
- 		put_io_context(bfqd->in_service_bic->icq.ioc);
-+#endif
- 		bfqd->in_service_bic = NULL;
- 	}
- 
-
-From 84cc7140cb4f0574710625f51abbb076a1dd2920 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Fri, 3 Mar 2017 09:31:14 +0100
-Subject: [PATCH 17/51] Add checks and extra log messages - Part II
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-mq-iosched.c | 42 ++++++++++++++++++++++++++++++++++++++++--
- block/bfq-sched.c      |  1 +
- 2 files changed, 41 insertions(+), 2 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 69ef3761c95d..5707d42b160d 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -1567,6 +1567,7 @@ static struct request *bfq_find_rq_fmerge(struct bfq_data *bfqd,
- {
- 	struct bfq_queue *bfqq = bfqd->bio_bfqq;
- 
-+	BUG_ON(!bfqd->bio_bfqq_set);
- 
- 	if (bfqq)
- 		return elv_rb_find(&bfqq->sort_list, bio_end_sector(bio));
-@@ -1719,6 +1720,7 @@ static bool bfq_bio_merge(struct blk_mq_hw_ctx *hctx, struct bio *bio)
- 	if (free)
- 		blk_mq_free_request(free);
- 	bfqd->bio_bfqq_set = false;
-+	BUG_ON(bfqd->ioc_to_put);
- 	spin_unlock_irq(&bfqd->lock);
- 
- 	return ret;
-@@ -1781,6 +1783,7 @@ static void bfq_request_merged(struct request_queue *q, struct request *req,
- 			bfq_updated_next_req(bfqd, bfqq);
- 			bfq_pos_tree_add_move(bfqd, bfqq);
- 		}
-+		BUG_ON(bfqd->ioc_to_put);
- 		spin_unlock_irq(&bfqd->lock);
- 	}
- }
-@@ -1824,6 +1827,7 @@ static void bfq_requests_merged(struct request_queue *q, struct request *rq,
- 
- 	bfq_remove_request(q, next);
- 
-+	BUG_ON(bfqq->bfqd->ioc_to_put);
- 	spin_unlock_irq(&bfqq->bfqd->lock);
- end:
- 	bfqg_stats_update_io_merged(bfqq_group(bfqq), next->cmd_flags);
-@@ -2195,9 +2199,11 @@ bfq_merge_bfqqs(struct bfq_data *bfqd, struct bfq_io_cq *bic,
- {
- 	bfq_log_bfqq(bfqd, bfqq, "merging with queue %lu",
- 		     (unsigned long) new_bfqq->pid);
-+	BUG_ON(bfqq->bic && bfqq->bic == new_bfqq->bic);
- 	/* Save weight raising and idle window of the merged queues */
- 	bfq_bfqq_save_state(bfqq);
- 	bfq_bfqq_save_state(new_bfqq);
-+
- 	if (bfq_bfqq_IO_bound(bfqq))
- 		bfq_mark_bfqq_IO_bound(new_bfqq);
- 	bfq_clear_bfqq_IO_bound(bfqq);
-@@ -2276,6 +2282,7 @@ static bool bfq_allow_bio_merge(struct request_queue *q, struct request *rq,
- 	bool is_sync = op_is_sync(bio->bi_opf);
- 	struct bfq_queue *bfqq = bfqd->bio_bfqq, *new_bfqq;
- 
-+	assert_spin_locked(&bfqd->lock);
- 	/*
- 	 * Disallow merge of a sync bio into an async request.
- 	 */
-@@ -2286,6 +2293,7 @@ static bool bfq_allow_bio_merge(struct request_queue *q, struct request *rq,
- 	 * Lookup the bfqq that this bio will be queued with. Allow
- 	 * merge only if rq is queued there.
- 	 */
-+	BUG_ON(!bfqd->bio_bfqq_set);
- 	if (!bfqq)
- 		return false;
- 
-@@ -2294,6 +2302,7 @@ static bool bfq_allow_bio_merge(struct request_queue *q, struct request *rq,
- 	 * of the queues of possible cooperating processes.
- 	 */
- 	new_bfqq = bfq_setup_cooperator(bfqd, bfqq, bio, false);
-+	BUG_ON(new_bfqq == bfqq);
- 	if (new_bfqq) {
- 		/*
- 		 * bic still points to bfqq, then it has not yet been
-@@ -4040,6 +4049,8 @@ static void bfq_put_queue(struct bfq_queue *bfqq)
- 	struct bfq_group *bfqg = bfqq_group(bfqq);
- #endif
- 
-+	assert_spin_locked(&bfqq->bfqd->lock);
-+
- 	BUG_ON(bfqq->ref <= 0);
- 
- 	if (bfqq->bfqd)
-@@ -4119,6 +4130,7 @@ static void bfq_exit_icq_bfqq(struct bfq_io_cq *bic, bool is_sync)
- 		unsigned long flags;
- 
- 		spin_lock_irqsave(&bfqd->lock, flags);
-+		BUG_ON(bfqd->ioc_to_put);
- 		/*
- 		 * If the bic is using a shared queue, put the
- 		 * reference taken on the io_context when the bic
-@@ -4567,10 +4579,12 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
- 
- 	spin_lock_irq(&bfqd->lock);
- 	if (blk_mq_sched_try_insert_merge(q, rq)) {
-+		BUG_ON(bfqd->ioc_to_put);
- 		spin_unlock_irq(&bfqd->lock);
- 		return;
- 	}
- 
-+	BUG_ON(bfqd->ioc_to_put);
- 	spin_unlock_irq(&bfqd->lock);
- 
- 	blk_mq_sched_request_inserted(rq);
-@@ -4785,6 +4799,7 @@ static void bfq_put_rq_private(struct request_queue *q, struct request *rq)
- 		unsigned long flags;
- 
- 		spin_lock_irqsave(&bfqd->lock, flags);
-+		BUG_ON(bfqd->ioc_to_put);
- 
- 		bfq_completed_request(bfqq, bfqd);
- 		bfq_put_rq_priv_body(bfqq);
-@@ -4855,13 +4870,28 @@ static struct bfq_queue *bfq_get_bfqq_handle_split(struct bfq_data *bfqd,
- 	if (bfqq)
- 		bfq_put_queue(bfqq);
- 	bfqq = bfq_get_queue(bfqd, bio, is_sync, bic);
-+	BUG_ON(!hlist_unhashed(&bfqq->burst_list_node));
- 
- 	bic_set_bfqq(bic, bfqq, is_sync);
- 	if (split && is_sync) {
-+		bfq_log_bfqq(bfqd, bfqq,
-+			     "get_request: was_in_list %d "
-+			     "was_in_large_burst %d "
-+			     "large burst in progress %d",
-+			     bic->was_in_burst_list,
-+			     bic->saved_in_large_burst,
-+			     bfqd->large_burst);
-+
- 		if ((bic->was_in_burst_list && bfqd->large_burst) ||
--		    bic->saved_in_large_burst)
-+		    bic->saved_in_large_burst) {
-+			bfq_log_bfqq(bfqd, bfqq,
-+				     "get_request: marking in "
-+				     "large burst");
- 			bfq_mark_bfqq_in_large_burst(bfqq);
--		else {
-+		} else {
-+			bfq_log_bfqq(bfqd, bfqq,
-+				     "get_request: clearing in "
-+				     "large burst");
- 			bfq_clear_bfqq_in_large_burst(bfqq);
- 			if (bic->was_in_burst_list)
- 				hlist_add_head(&bfqq->burst_list_node,
-@@ -4897,10 +4927,12 @@ static int bfq_get_rq_private(struct request_queue *q, struct request *rq,
- 
- 	bfqq = bfq_get_bfqq_handle_split(bfqd, bic, bio, false, is_sync,
- 					 &new_queue);
-+	BUG_ON(bfqd->ioc_to_put);
- 
- 	if (unlikely(!new_queue)) {
- 		/* If the queue was seeky for too long, break it apart. */
- 		if (bfq_bfqq_coop(bfqq) && bfq_bfqq_split_coop(bfqq)) {
-+			BUG_ON(!is_sync);
- 			bfq_log_bfqq(bfqd, bfqq, "breaking apart bfqq");
- 
- 			/* Update bic before losing reference to bfqq */
-@@ -4923,6 +4955,9 @@ static int bfq_get_rq_private(struct request_queue *q, struct request *rq,
- 								 NULL);
- 			else
- 				bfqq_already_existing = true;
-+
-+			BUG_ON(!bfqq);
-+			BUG_ON(bfqq == &bfqd->oom_bfqq);
- 		}
- 	}
- 
-@@ -4976,6 +5011,8 @@ static void bfq_idle_slice_timer_body(struct bfq_queue *bfqq)
- 
- 	BUG_ON(!bfqd);
- 	spin_lock_irqsave(&bfqd->lock, flags);
-+	BUG_ON(bfqd->ioc_to_put);
-+
- 	bfq_log_bfqq(bfqd, bfqq, "handling slice_timer expiration");
- 	bfq_clear_bfqq_wait_request(bfqq);
- 
-@@ -5083,6 +5120,7 @@ static void bfq_exit_queue(struct elevator_queue *e)
- 	spin_lock_irq(&bfqd->lock);
- 	list_for_each_entry_safe(bfqq, n, &bfqd->idle_list, bfqq_list)
- 		bfq_deactivate_bfqq(bfqd, bfqq, false, false);
-+	BUG_ON(bfqd->ioc_to_put);
- 	spin_unlock_irq(&bfqd->lock);
- 
- 	hrtimer_cancel(&bfqd->idle_slice_timer);
-diff --git a/block/bfq-sched.c b/block/bfq-sched.c
-index a5c8b4acd33c..85e59eeb3569 100644
---- a/block/bfq-sched.c
-+++ b/block/bfq-sched.c
-@@ -1906,6 +1906,7 @@ static void __bfq_bfqd_reset_in_service(struct bfq_data *bfqd)
- 
- 	if (bfqd->in_service_bic) {
- #ifdef BFQ_MQ
-+		BUG_ON(bfqd->ioc_to_put);
- 		/*
- 		 * Schedule the release of a reference to
- 		 * bfqd->in_service_bic->icq.ioc to right after the
-
-From 3d54cb804f1db2e08ce4a6cc335868538542f587 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Wed, 22 Feb 2017 11:30:01 +0100
-Subject: [PATCH 18/51] Fix unbalanced increment of rq_in_driver
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-mq-iosched.c | 52 +++++++++++++++++++++++++++++++++++++++++---------
- 1 file changed, 43 insertions(+), 9 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 5707d42b160d..9cbcb8d43d81 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -3936,9 +3936,45 @@ static struct request *__bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
- 		rq = list_first_entry(&bfqd->dispatch, struct request,
- 				      queuelist);
- 		list_del_init(&rq->queuelist);
-+
- 		bfq_log(bfqd,
- 			"dispatch requests: picked %p from dispatch list", rq);
--		goto exit;
-+		bfqq = RQ_BFQQ(rq);
-+
-+		if (bfqq) {
-+			/*
-+			 * Increment counters here, because this
-+			 * dispatch does not follow the standard
-+			 * dispatch flow (where counters are
-+			 * incremented)
-+			 */
-+			bfqq->dispatched++;
-+
-+			goto inc_in_driver_start_rq;
-+		}
-+
-+		/*
-+		 * We exploit the put_rq_private hook to decrement
-+		 * rq_in_driver, but put_rq_private will not be
-+		 * invoked on this request. So, to avoid unbalance,
-+		 * just start this request, without incrementing
-+		 * rq_in_driver. As a negative consequence,
-+		 * rq_in_driver is deceptively lower than it should be
-+		 * while this request is in service. This may cause
-+		 * bfq_schedule_dispatch to be invoked uselessly.
-+		 *
-+		 * As for implementing an exact solution, the
-+		 * put_request hook, if defined, is probably invoked
-+		 * also on this request. So, by exploiting this hook,
-+		 * we could 1) increment rq_in_driver here, and 2)
-+		 * decrement it in put_request. Such a solution would
-+		 * let the value of the counter be always accurate,
-+		 * but it would entail using an extra interface
-+		 * function. This cost seems higher than the benefit,
-+		 * being the frequency of non-elevator-private
-+		 * requests very low.
-+		 */
-+		goto start_rq;
- 	}
- 
- 	bfq_log(bfqd, "dispatch requests: %d busy queues", bfqd->busy_queues);
-@@ -3973,10 +4009,12 @@ static struct request *__bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
- 
- 	BUG_ON(bfqq->next_rq == NULL &&
- 	       bfqq->entity.budget < bfqq->entity.service);
--exit:
-+
- 	if (rq) {
--		rq->rq_flags |= RQF_STARTED;
-+	inc_in_driver_start_rq:
- 		bfqd->rq_in_driver++;
-+	start_rq:
-+		rq->rq_flags |= RQF_STARTED;
- 		if (bfqq)
- 			bfq_log_bfqq(bfqd, bfqq,
- 				"dispatched %s request %p, rq_in_driver %d",
-@@ -3992,6 +4030,7 @@ static struct request *__bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
- 		"returned NULL request, rq_in_driver %d",
- 			bfqd->rq_in_driver);
- 
-+exit:
- 	return rq;
- }
- 
-@@ -4591,15 +4630,10 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
- 
- 	spin_lock_irq(&bfqd->lock);
- 	if (at_head || blk_rq_is_passthrough(rq)) {
--		struct bfq_queue *bfqq = RQ_BFQQ(rq);
--
- 		if (at_head)
- 			list_add(&rq->queuelist, &bfqd->dispatch);
- 		else
- 			list_add_tail(&rq->queuelist, &bfqd->dispatch);
--
--		if (bfqq)
--			bfqq->dispatched++;
- 	} else {
- 		__bfq_insert_request(bfqd, rq);
- 
-@@ -4966,7 +5000,7 @@ static int bfq_get_rq_private(struct request_queue *q, struct request *rq,
- 		     "get_request: new allocated %d", bfqq->allocated);
- 
- 	bfqq->ref++;
--	bfq_log_bfqq(bfqd, bfqq, "get_request: bfqq %p, %d", bfqq, bfqq->ref);
-+	bfq_log_bfqq(bfqd, bfqq, "get_request %p: bfqq %p, %d", rq, bfqq, bfqq->ref);
- 
- 	rq->elv.priv[0] = bic;
- 	rq->elv.priv[1] = bfqq;
-
-From 7ba977d696b239569b4cd233aebc99e136ecf487 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Fri, 3 Mar 2017 09:39:35 +0100
-Subject: [PATCH 19/51] Add checks and extra log messages - Part III
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-mq-iosched.c | 11 +++++++++++
- 1 file changed, 11 insertions(+)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 9cbcb8d43d81..24b529a2edc7 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -4630,10 +4630,21 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
- 
- 	spin_lock_irq(&bfqd->lock);
- 	if (at_head || blk_rq_is_passthrough(rq)) {
-+		struct bfq_queue *bfqq = RQ_BFQQ(rq);
-+
- 		if (at_head)
- 			list_add(&rq->queuelist, &bfqd->dispatch);
- 		else
- 			list_add_tail(&rq->queuelist, &bfqd->dispatch);
-+
-+		if (bfqq)
-+			bfq_log_bfqq(bfqd, bfqq,
-+				     "insert_request %p in disp: at_head %d",
-+				     rq, at_head);
-+		else
-+			bfq_log(bfqd,
-+				"insert_request %p in disp: at_head %d",
-+				rq, at_head);
- 	} else {
- 		__bfq_insert_request(bfqd, rq);
- 
-
-From c94e47b2908600b8ba89f84b0ac7febddd313141 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Fri, 17 Feb 2017 14:28:02 +0100
-Subject: [PATCH 20/51] TESTING: Check wrong invocation of merge and
- put_rq_priv functions
-
-Check that merge functions are not invoked on requests queued in the
-dispatch queue, and that neither put_rq_private is invoked on these
-requests if, in addition, they have not passed through get_rq_private.
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-mq-iosched.c | 22 ++++++++++++++++++++++
- include/linux/blkdev.h |  2 ++
- 2 files changed, 24 insertions(+)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 24b529a2edc7..b4d40bb712d2 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -1746,6 +1746,8 @@ static int bfq_request_merge(struct request_queue *q, struct request **req,
- static void bfq_request_merged(struct request_queue *q, struct request *req,
- 			       enum elv_merge type)
- {
-+	BUG_ON(req->rq_flags & RQF_DISP_LIST);
-+
- 	if (type == ELEVATOR_FRONT_MERGE &&
- 	    rb_prev(&req->rb_node) &&
- 	    blk_rq_pos(req) <
-@@ -1795,6 +1797,8 @@ static void bfq_requests_merged(struct request_queue *q, struct request *rq,
- 
- 	BUG_ON(!RQ_BFQQ(rq));
- 	BUG_ON(!RQ_BFQQ(next));
-+	BUG_ON(rq->rq_flags & RQF_DISP_LIST);
-+	BUG_ON(next->rq_flags & RQF_DISP_LIST);
- 
- 	if (!RB_EMPTY_NODE(&rq->rb_node))
- 		goto end;
-@@ -3936,6 +3940,7 @@ static struct request *__bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
- 		rq = list_first_entry(&bfqd->dispatch, struct request,
- 				      queuelist);
- 		list_del_init(&rq->queuelist);
-+		rq->rq_flags &= ~RQF_DISP_LIST;
- 
- 		bfq_log(bfqd,
- 			"dispatch requests: picked %p from dispatch list", rq);
-@@ -3950,6 +3955,17 @@ static struct request *__bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
- 			 */
- 			bfqq->dispatched++;
- 
-+			/*
-+			 * TESTING: reset DISP_LIST flag, because: 1)
-+			 * this rq this request has passed through
-+			 * get_rq_private, 2) then it will have
-+			 * put_rq_private invoked on it, and 3) in
-+			 * put_rq_private we use this flag to check
-+			 * that put_rq_private is not invoked on
-+			 * requests for which get_rq_private has been
-+			 * invoked.
-+			 */
-+			rq->rq_flags &= ~RQF_DISP_LIST;
- 			goto inc_in_driver_start_rq;
- 		}
- 
-@@ -4637,6 +4653,7 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
- 		else
- 			list_add_tail(&rq->queuelist, &bfqd->dispatch);
- 
-+		rq->rq_flags |= RQF_DISP_LIST;
- 		if (bfqq)
- 			bfq_log_bfqq(bfqd, bfqq,
- 				     "insert_request %p in disp: at_head %d",
-@@ -4824,6 +4841,10 @@ static void bfq_put_rq_private(struct request_queue *q, struct request *rq)
- 	bfqd = bfqq->bfqd;
- 	BUG_ON(!bfqd);
- 
-+	if (rq->rq_flags & RQF_DISP_LIST) {
-+		pr_crit("putting disp rq %p for %d", rq, bfqq->pid);
-+		BUG();
-+	}
- 	BUG_ON(rq->rq_flags & RQF_QUEUED);
- 	BUG_ON(!(rq->rq_flags & RQF_ELVPRIV));
- 
-@@ -5015,6 +5036,7 @@ static int bfq_get_rq_private(struct request_queue *q, struct request *rq,
- 
- 	rq->elv.priv[0] = bic;
- 	rq->elv.priv[1] = bfqq;
-+	rq->rq_flags &= ~RQF_DISP_LIST;
- 
- 	/*
- 	 * If a bfq_queue has only one process reference, it is owned
-diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
-index 10f892ca585d..0048e59e6d07 100644
---- a/include/linux/blkdev.h
-+++ b/include/linux/blkdev.h
-@@ -121,6 +121,8 @@ typedef __u32 __bitwise req_flags_t;
- /* Look at ->special_vec for the actual data payload instead of the
-    bio chain. */
- #define RQF_SPECIAL_PAYLOAD	((__force req_flags_t)(1 << 18))
-+/* DEBUG: rq in bfq-mq dispatch list */
-+#define RQF_DISP_LIST	((__force req_flags_t)(1 << 19))
- 
- /* flags that prevent us from merging requests: */
- #define RQF_NOMERGE_FLAGS \
-
-From 49206f9052d13c96d49dbc36c612bed41b2d6552 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Sat, 25 Feb 2017 17:38:05 +0100
-Subject: [PATCH 21/51] Complete support for cgroups
-
-This commit completes cgroups support for bfq-mq. In particular, it deals with
-a sort of circular dependency introduced in blk-mq: the function
-blkcg_activate_policy, invoked during scheduler initialization, triggers the
-invocation of the has_work scheduler hook (before the init function is
-finished). To adress this issue, this commit moves the invocation of
-blkcg_activate_policy after the initialization of all the fields that could be
-initialized before invoking blkcg_activate_policy itself. This enables has_work
-to correctly return false, and thus to prevent the blk-mq stack from invoking
-further scheduler hooks before the init function is finished.
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/Kconfig.iosched  |   9 +++++
- block/bfq-mq-iosched.c | 108 ++++++++++++++++++++++++++++---------------------
- block/bfq-mq.h         |   2 +-
- 3 files changed, 72 insertions(+), 47 deletions(-)
-
-diff --git a/block/Kconfig.iosched b/block/Kconfig.iosched
-index 2d94af3d8b0a..299a6861fb90 100644
---- a/block/Kconfig.iosched
-+++ b/block/Kconfig.iosched
-@@ -106,6 +106,15 @@ config MQ_IOSCHED_BFQ
- 	guarantees a low latency to interactive and soft real-time
- 	applications.  Details in Documentation/block/bfq-iosched.txt
- 
-+config MQ_BFQ_GROUP_IOSCHED
-+	bool "BFQ-MQ hierarchical scheduling support"
-+	depends on MQ_IOSCHED_BFQ && BLK_CGROUP
-+	default n
-+	---help---
-+
-+	Enable hierarchical scheduling in BFQ-MQ, using the blkio
-+	(cgroups-v1) or io (cgroups-v2) controller.
-+
- config MQ_IOSCHED_DEADLINE
- 	tristate "MQ deadline I/O scheduler"
- 	default y
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index b4d40bb712d2..02a1e7fd0ea4 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -88,7 +88,6 @@
- #include "blk-mq.h"
- #include "blk-mq-tag.h"
- #include "blk-mq-sched.h"
--#undef CONFIG_BFQ_GROUP_IOSCHED /* cgroups support not yet functional */
- #include "bfq-mq.h"
- 
- /* Expiration time of sync (0) and async (1) requests, in ns. */
-@@ -233,15 +232,6 @@ static struct bfq_io_cq *bfq_bic_lookup(struct bfq_data *bfqd,
- 	return NULL;
- }
- 
--#define BFQ_MQ
--#include "bfq-sched.c"
--#include "bfq-cgroup-included.c"
--
--#define bfq_class_idle(bfqq)	((bfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
--#define bfq_class_rt(bfqq)	((bfqq)->ioprio_class == IOPRIO_CLASS_RT)
--
--#define bfq_sample_valid(samples)	((samples) > 80)
--
- /*
-  * Scheduler run of queue, if there are requests pending and no one in the
-  * driver that will restart queueing.
-@@ -255,6 +245,43 @@ static void bfq_schedule_dispatch(struct bfq_data *bfqd)
- }
- 
- /*
-+ * Next two functions release bfqd->lock and put the io context
-+ * pointed by bfqd->ioc_to_put. This delayed put is used to not risk
-+ * to take an ioc->lock while the scheduler lock is being held.
-+ */
-+static void bfq_unlock_put_ioc(struct bfq_data *bfqd)
-+{
-+	struct io_context *ioc_to_put = bfqd->ioc_to_put;
-+
-+	bfqd->ioc_to_put = NULL;
-+	spin_unlock_irq(&bfqd->lock);
-+
-+	if (ioc_to_put)
-+		put_io_context(ioc_to_put);
-+}
-+
-+static void bfq_unlock_put_ioc_restore(struct bfq_data *bfqd,
-+				       unsigned long flags)
-+{
-+	struct io_context *ioc_to_put = bfqd->ioc_to_put;
-+
-+	bfqd->ioc_to_put = NULL;
-+	spin_unlock_irqrestore(&bfqd->lock, flags);
-+
-+	if (ioc_to_put)
-+		put_io_context(ioc_to_put);
-+}
-+
-+#define BFQ_MQ
-+#include "bfq-sched.c"
-+#include "bfq-cgroup-included.c"
-+
-+#define bfq_class_idle(bfqq)	((bfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
-+#define bfq_class_rt(bfqq)	((bfqq)->ioprio_class == IOPRIO_CLASS_RT)
-+
-+#define bfq_sample_valid(samples)	((samples) > 80)
-+
-+/*
-  * Lifted from AS - choose which of rq1 and rq2 that is best served now.
-  * We choose the request that is closesr to the head right now.  Distance
-  * behind the head is penalized and only allowed to a certain extent.
-@@ -4050,34 +4077,6 @@ static struct request *__bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
- 	return rq;
- }
- 
--/*
-- * Next two functions release bfqd->lock and put the io context
-- * pointed by bfqd->ioc_to_put. This delayed put is used to not risk
-- * to take an ioc->lock while the scheduler lock is being held.
-- */
--static void bfq_unlock_put_ioc(struct bfq_data *bfqd)
--{
--	struct io_context *ioc_to_put = bfqd->ioc_to_put;
--
--	bfqd->ioc_to_put = NULL;
--	spin_unlock_irq(&bfqd->lock);
--
--	if (ioc_to_put)
--		put_io_context(ioc_to_put);
--}
--
--static void bfq_unlock_put_ioc_restore(struct bfq_data *bfqd,
--				       unsigned long flags)
--{
--	struct io_context *ioc_to_put = bfqd->ioc_to_put;
--
--	bfqd->ioc_to_put = NULL;
--	spin_unlock_irqrestore(&bfqd->lock, flags);
--
--	if (ioc_to_put)
--		put_io_context(ioc_to_put);
--}
--
- static struct request *bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
- {
- 	struct bfq_data *bfqd = hctx->queue->elevator->elevator_data;
-@@ -5239,6 +5238,10 @@ static int bfq_init_queue(struct request_queue *q, struct elevator_type *e)
- 	}
- 	eq->elevator_data = bfqd;
- 
-+	spin_lock_irq(q->queue_lock);
-+	q->elevator = eq;
-+	spin_unlock_irq(q->queue_lock);
-+
- 	/*
- 	 * Our fallback bfqq if bfq_find_alloc_queue() runs into OOM issues.
- 	 * Grab a permanent reference to it, so that the normal code flow
-@@ -5261,12 +5264,7 @@ static int bfq_init_queue(struct request_queue *q, struct elevator_type *e)
- 	bfqd->oom_bfqq.entity.prio_changed = 1;
- 
- 	bfqd->queue = q;
--
--	bfqd->root_group = bfq_create_group_hierarchy(bfqd, q->node);
--	if (!bfqd->root_group)
--		goto out_free;
--	bfq_init_root_group(bfqd->root_group, bfqd);
--	bfq_init_entity(&bfqd->oom_bfqq.entity, bfqd->root_group);
-+	INIT_LIST_HEAD(&bfqd->dispatch);
- 
- 	hrtimer_init(&bfqd->idle_slice_timer, CLOCK_MONOTONIC,
- 		     HRTIMER_MODE_REL);
-@@ -5324,9 +5322,27 @@ static int bfq_init_queue(struct request_queue *q, struct elevator_type *e)
- 	bfqd->device_speed = BFQ_BFQD_FAST;
- 
- 	spin_lock_init(&bfqd->lock);
--	INIT_LIST_HEAD(&bfqd->dispatch);
- 
--	q->elevator = eq;
-+	/*
-+	 * The invocation of the next bfq_create_group_hierarchy
-+	 * function is the head of a chain of function calls
-+	 * (bfq_create_group_hierarchy->blkcg_activate_policy->
-+	 * blk_mq_freeze_queue) that may lead to the invocation of the
-+	 * has_work hook function. For this reason,
-+	 * bfq_create_group_hierarchy is invoked only after all
-+	 * scheduler data has been initialized, apart from the fields
-+	 * that can be initialized only after invoking
-+	 * bfq_create_group_hierarchy. This, in particular, enables
-+	 * has_work to correctly return false. Of course, to avoid
-+	 * other inconsistencies, the blk-mq stack must then refrain
-+	 * from invoking further scheduler hooks before this init
-+	 * function is finished.
-+	*/
-+	bfqd->root_group = bfq_create_group_hierarchy(bfqd, q->node);
-+	if (!bfqd->root_group)
-+		goto out_free;
-+	bfq_init_root_group(bfqd->root_group, bfqd);
-+	bfq_init_entity(&bfqd->oom_bfqq.entity, bfqd->root_group);
- 
- 	return 0;
- 
-diff --git a/block/bfq-mq.h b/block/bfq-mq.h
-index bd83f1c02573..2c81c02bccc4 100644
---- a/block/bfq-mq.h
-+++ b/block/bfq-mq.h
-@@ -20,7 +20,7 @@
- #include <linux/blk-cgroup.h>
- 
- /* see comments on CONFIG_BFQ_GROUP_IOSCHED in bfq.h */
--#ifdef CONFIG_BFQ_MQ_GROUP_IOSCHED
-+#ifdef CONFIG_MQ_BFQ_GROUP_IOSCHED
- #define BFQ_GROUP_IOSCHED_ENABLED
- #endif
- 
-
-From 62d12db23ce14d2716b5cff7d2635fbc817b96d0 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Fri, 17 Mar 2017 06:15:18 +0100
-Subject: [PATCH 22/51] Remove all get and put of I/O contexts
-
-When a bfq queue is set in service and when it is merged, a reference
-to the I/O context associated with the queue is taken. This reference
-is then released when the queue is deselected from service or
-split. More precisely, the release of the reference is postponed to
-when the scheduler lock is released, to avoid nesting between the
-scheduler and the I/O-context lock. In fact, such nesting would lead
-to deadlocks, because of other code paths that take the same locks in
-the opposite order. This postponing of I/O-context releases does
-complicate code.
-
-This commit addresses this issue by modifying involved operations in
-such a way to not need to get the above I/O-context references any
-more. Then it also removes any get and release of these references.
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-cgroup-included.c |   2 +-
- block/bfq-mq-iosched.c      | 127 ++++++++------------------------------------
- block/bfq-mq.h              |  11 ----
- block/bfq-sched.c           |  17 ------
- 4 files changed, 22 insertions(+), 135 deletions(-)
-
-diff --git a/block/bfq-cgroup-included.c b/block/bfq-cgroup-included.c
-index cf59eeb7f08e..dfacca799b5e 100644
---- a/block/bfq-cgroup-included.c
-+++ b/block/bfq-cgroup-included.c
-@@ -773,7 +773,7 @@ static void bfq_pd_offline(struct blkg_policy_data *pd)
- 	bfq_put_async_queues(bfqd, bfqg);
- 
- #ifdef BFQ_MQ
--	bfq_unlock_put_ioc_restore(bfqd, flags);
-+	spin_unlock_irqrestore(&bfqd->lock, flags);
- #endif
- 	/*
- 	 * @blkg is going offline and will be ignored by
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 02a1e7fd0ea4..8e7589d3280f 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -244,34 +244,6 @@ static void bfq_schedule_dispatch(struct bfq_data *bfqd)
- 	}
- }
- 
--/*
-- * Next two functions release bfqd->lock and put the io context
-- * pointed by bfqd->ioc_to_put. This delayed put is used to not risk
-- * to take an ioc->lock while the scheduler lock is being held.
-- */
--static void bfq_unlock_put_ioc(struct bfq_data *bfqd)
--{
--	struct io_context *ioc_to_put = bfqd->ioc_to_put;
--
--	bfqd->ioc_to_put = NULL;
--	spin_unlock_irq(&bfqd->lock);
--
--	if (ioc_to_put)
--		put_io_context(ioc_to_put);
--}
--
--static void bfq_unlock_put_ioc_restore(struct bfq_data *bfqd,
--				       unsigned long flags)
--{
--	struct io_context *ioc_to_put = bfqd->ioc_to_put;
--
--	bfqd->ioc_to_put = NULL;
--	spin_unlock_irqrestore(&bfqd->lock, flags);
--
--	if (ioc_to_put)
--		put_io_context(ioc_to_put);
--}
--
- #define BFQ_MQ
- #include "bfq-sched.c"
- #include "bfq-cgroup-included.c"
-@@ -1747,7 +1719,6 @@ static bool bfq_bio_merge(struct blk_mq_hw_ctx *hctx, struct bio *bio)
- 	if (free)
- 		blk_mq_free_request(free);
- 	bfqd->bio_bfqq_set = false;
--	BUG_ON(bfqd->ioc_to_put);
- 	spin_unlock_irq(&bfqd->lock);
- 
- 	return ret;
-@@ -1812,7 +1783,6 @@ static void bfq_request_merged(struct request_queue *q, struct request *req,
- 			bfq_updated_next_req(bfqd, bfqq);
- 			bfq_pos_tree_add_move(bfqd, bfqq);
- 		}
--		BUG_ON(bfqd->ioc_to_put);
- 		spin_unlock_irq(&bfqd->lock);
- 	}
- }
-@@ -1858,7 +1828,6 @@ static void bfq_requests_merged(struct request_queue *q, struct request *rq,
- 
- 	bfq_remove_request(q, next);
- 
--	BUG_ON(bfqq->bfqd->ioc_to_put);
- 	spin_unlock_irq(&bfqq->bfqd->lock);
- end:
- 	bfqg_stats_update_io_merged(bfqq_group(bfqq), next->cmd_flags);
-@@ -2035,20 +2004,18 @@ bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq)
- 	 * first time that the requests of some process are redirected to
- 	 * it.
- 	 *
--	 * We redirect bfqq to new_bfqq and not the opposite, because we
--	 * are in the context of the process owning bfqq, hence we have
--	 * the io_cq of this process. So we can immediately configure this
--	 * io_cq to redirect the requests of the process to new_bfqq.
-+	 * We redirect bfqq to new_bfqq and not the opposite, because
-+	 * we are in the context of the process owning bfqq, thus we
-+	 * have the io_cq of this process. So we can immediately
-+	 * configure this io_cq to redirect the requests of the
-+	 * process to new_bfqq. In contrast, the io_cq of new_bfqq is
-+	 * not available any more (new_bfqq->bic == NULL).
- 	 *
--	 * NOTE, even if new_bfqq coincides with the in-service queue, the
--	 * io_cq of new_bfqq is not available, because, if the in-service
--	 * queue is shared, bfqd->in_service_bic may not point to the
--	 * io_cq of the in-service queue.
--	 * Redirecting the requests of the process owning bfqq to the
--	 * currently in-service queue is in any case the best option, as
--	 * we feed the in-service queue with new requests close to the
--	 * last request served and, by doing so, hopefully increase the
--	 * throughput.
-+	 * Anyway, even in case new_bfqq coincides with the in-service
-+	 * queue, redirecting requests the in-service queue is the
-+	 * best option, as we feed the in-service queue with new
-+	 * requests close to the last request served and, by doing so,
-+	 * are likely to increase the throughput.
- 	 */
- 	bfqq->new_bfqq = new_bfqq;
- 	new_bfqq->ref += process_refs;
-@@ -2147,13 +2114,13 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 	in_service_bfqq = bfqd->in_service_queue;
- 
- 	if (in_service_bfqq && in_service_bfqq != bfqq &&
--	    bfqd->in_service_bic && wr_from_too_long(in_service_bfqq)
-+	    wr_from_too_long(in_service_bfqq)
- 	    && likely(in_service_bfqq == &bfqd->oom_bfqq))
- 		bfq_log_bfqq(bfqd, bfqq,
- 		"would have tried merge with in-service-queue, but wr");
- 
--	if (!in_service_bfqq || in_service_bfqq == bfqq ||
--	    !bfqd->in_service_bic || wr_from_too_long(in_service_bfqq) ||
-+	if (!in_service_bfqq || in_service_bfqq == bfqq
-+	    || wr_from_too_long(in_service_bfqq) ||
- 	    unlikely(in_service_bfqq == &bfqd->oom_bfqq))
- 		goto check_scheduled;
- 
-@@ -2214,16 +2181,6 @@ static void bfq_bfqq_save_state(struct bfq_queue *bfqq)
- 	BUG_ON(time_is_after_jiffies(bfqq->last_wr_start_finish));
- }
- 
--static void bfq_get_bic_reference(struct bfq_queue *bfqq)
--{
--	/*
--	 * If bfqq->bic has a non-NULL value, the bic to which it belongs
--	 * is about to begin using a shared bfq_queue.
--	 */
--	if (bfqq->bic)
--		atomic_long_inc(&bfqq->bic->icq.ioc->refcount);
--}
--
- static void
- bfq_merge_bfqqs(struct bfq_data *bfqd, struct bfq_io_cq *bic,
- 		struct bfq_queue *bfqq, struct bfq_queue *new_bfqq)
-@@ -2280,12 +2237,6 @@ bfq_merge_bfqqs(struct bfq_data *bfqd, struct bfq_io_cq *bic,
- 		     bfqd->wr_busy_queues);
- 
- 	/*
--	 * Grab a reference to the bic, to prevent it from being destroyed
--	 * before being possibly touched by a bfq_split_bfqq().
--	 */
--	bfq_get_bic_reference(bfqq);
--	bfq_get_bic_reference(new_bfqq);
--	/*
- 	 * Merge queues (that is, let bic redirect its requests to new_bfqq)
- 	 */
- 	bic_set_bfqq(bic, new_bfqq, 1);
-@@ -2472,16 +2423,10 @@ static struct bfq_queue *bfq_set_in_service_queue(struct bfq_data *bfqd)
- static void bfq_arm_slice_timer(struct bfq_data *bfqd)
- {
- 	struct bfq_queue *bfqq = bfqd->in_service_queue;
--	struct bfq_io_cq *bic;
- 	u32 sl;
- 
- 	BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list));
- 
--	/* Processes have exited, don't wait. */
--	bic = bfqd->in_service_bic;
--	if (!bic || atomic_read(&bic->icq.ioc->active_ref) == 0)
--		return;
--
- 	bfq_mark_bfqq_wait_request(bfqq);
- 
- 	/*
-@@ -3922,11 +3867,6 @@ static struct request *bfq_dispatch_rq_from_bfqq(struct bfq_data *bfqd,
- 		     bfq_bfqq_budget_left(bfqq),
- 		     bfqq->dispatched);
- 
--	if (!bfqd->in_service_bic) {
--		atomic_long_inc(&RQ_BIC(rq)->icq.ioc->refcount);
--		bfqd->in_service_bic = RQ_BIC(rq);
--	}
--
- 	/*
- 	 * Expire bfqq, pretending that its budget expired, if bfqq
- 	 * belongs to CLASS_IDLE and other queues are waiting for
-@@ -4085,7 +4025,7 @@ static struct request *bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
- 	spin_lock_irq(&bfqd->lock);
- 
- 	rq = __bfq_dispatch_request(hctx);
--	bfq_unlock_put_ioc(bfqd);
-+	spin_unlock_irq(&bfqd->lock);
- 
- 	return rq;
- }
-@@ -4184,21 +4124,10 @@ static void bfq_exit_icq_bfqq(struct bfq_io_cq *bic, bool is_sync)
- 		unsigned long flags;
- 
- 		spin_lock_irqsave(&bfqd->lock, flags);
--		BUG_ON(bfqd->ioc_to_put);
--		/*
--		 * If the bic is using a shared queue, put the
--		 * reference taken on the io_context when the bic
--		 * started using a shared bfq_queue. This put cannot
--		 * make ioc->ref_count reach 0, then no ioc->lock
--		 * risks to be taken (leading to possible deadlock
--		 * scenarios).
--		 */
--		if (is_sync && bfq_bfqq_coop(bfqq))
--			put_io_context(bic->icq.ioc);
- 
- 		bfq_exit_bfqq(bfqd, bfqq);
- 		bic_set_bfqq(bic, NULL, is_sync);
--		bfq_unlock_put_ioc_restore(bfqd, flags);
-+		spin_unlock_irqrestore(&bfqd->lock, flags);
- 	}
- }
- 
-@@ -4633,12 +4562,10 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
- 
- 	spin_lock_irq(&bfqd->lock);
- 	if (blk_mq_sched_try_insert_merge(q, rq)) {
--		BUG_ON(bfqd->ioc_to_put);
- 		spin_unlock_irq(&bfqd->lock);
- 		return;
- 	}
- 
--	BUG_ON(bfqd->ioc_to_put);
- 	spin_unlock_irq(&bfqd->lock);
- 
- 	blk_mq_sched_request_inserted(rq);
-@@ -4671,7 +4598,7 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
- 		}
- 	}
- 
--	bfq_unlock_put_ioc(bfqd);
-+	spin_unlock_irq(&bfqd->lock);
- }
- 
- static void bfq_insert_requests(struct blk_mq_hw_ctx *hctx,
-@@ -4864,12 +4791,11 @@ static void bfq_put_rq_private(struct request_queue *q, struct request *rq)
- 		unsigned long flags;
- 
- 		spin_lock_irqsave(&bfqd->lock, flags);
--		BUG_ON(bfqd->ioc_to_put);
- 
- 		bfq_completed_request(bfqq, bfqd);
- 		bfq_put_rq_priv_body(bfqq);
- 
--		bfq_unlock_put_ioc_restore(bfqd, flags);
-+		spin_unlock_irqrestore(&bfqd->lock, flags);
- 	} else {
- 		/*
- 		 * Request rq may be still/already in the scheduler,
-@@ -4992,7 +4918,6 @@ static int bfq_get_rq_private(struct request_queue *q, struct request *rq,
- 
- 	bfqq = bfq_get_bfqq_handle_split(bfqd, bic, bio, false, is_sync,
- 					 &new_queue);
--	BUG_ON(bfqd->ioc_to_put);
- 
- 	if (unlikely(!new_queue)) {
- 		/* If the queue was seeky for too long, break it apart. */
-@@ -5005,14 +4930,6 @@ static int bfq_get_rq_private(struct request_queue *q, struct request *rq,
- 				bic->saved_in_large_burst = true;
- 
- 			bfqq = bfq_split_bfqq(bic, bfqq);
--			/*
--			 * A reference to bic->icq.ioc needs to be
--			 * released after a queue split. Do not do it
--			 * immediately, to not risk to possibly take
--			 * an ioc->lock while holding the scheduler
--			 * lock.
--			 */
--			bfqd->ioc_to_put = bic->icq.ioc;
- 
- 			if (!bfqq)
- 				bfqq = bfq_get_bfqq_handle_split(bfqd, bic, bio,
-@@ -5045,7 +4962,7 @@ static int bfq_get_rq_private(struct request_queue *q, struct request *rq,
- 	 */
- 	if (likely(bfqq != &bfqd->oom_bfqq) && bfqq_process_refs(bfqq) == 1) {
- 		bfqq->bic = bic;
--		if (bfqd->ioc_to_put) { /* if true, then there has been a split */
-+		if (split) {
- 			/*
- 			 * The queue has just been split from a shared
- 			 * queue: restore the idle window and the
-@@ -5059,7 +4976,7 @@ static int bfq_get_rq_private(struct request_queue *q, struct request *rq,
- 	if (unlikely(bfq_bfqq_just_created(bfqq)))
- 		bfq_handle_burst(bfqd, bfqq);
- 
--	bfq_unlock_put_ioc(bfqd);
-+	spin_unlock_irq(&bfqd->lock);
- 
- 	return 0;
- 
-@@ -5077,7 +4994,6 @@ static void bfq_idle_slice_timer_body(struct bfq_queue *bfqq)
- 
- 	BUG_ON(!bfqd);
- 	spin_lock_irqsave(&bfqd->lock, flags);
--	BUG_ON(bfqd->ioc_to_put);
- 
- 	bfq_log_bfqq(bfqd, bfqq, "handling slice_timer expiration");
- 	bfq_clear_bfqq_wait_request(bfqq);
-@@ -5108,7 +5024,7 @@ static void bfq_idle_slice_timer_body(struct bfq_queue *bfqq)
- 	bfq_bfqq_expire(bfqd, bfqq, true, reason);
- 
- schedule_dispatch:
--	bfq_unlock_put_ioc_restore(bfqd, flags);
-+	spin_unlock_irqrestore(&bfqd->lock, flags);
- 	bfq_schedule_dispatch(bfqd);
- }
- 
-@@ -5186,7 +5102,6 @@ static void bfq_exit_queue(struct elevator_queue *e)
- 	spin_lock_irq(&bfqd->lock);
- 	list_for_each_entry_safe(bfqq, n, &bfqd->idle_list, bfqq_list)
- 		bfq_deactivate_bfqq(bfqd, bfqq, false, false);
--	BUG_ON(bfqd->ioc_to_put);
- 	spin_unlock_irq(&bfqd->lock);
- 
- 	hrtimer_cancel(&bfqd->idle_slice_timer);
-diff --git a/block/bfq-mq.h b/block/bfq-mq.h
-index 2c81c02bccc4..36ee24a87dda 100644
---- a/block/bfq-mq.h
-+++ b/block/bfq-mq.h
-@@ -458,8 +458,6 @@ struct bfq_data {
- 
- 	/* bfq_queue in service */
- 	struct bfq_queue *in_service_queue;
--	/* bfq_io_cq (bic) associated with the @in_service_queue */
--	struct bfq_io_cq *in_service_bic;
- 
- 	/* on-disk position of the last served request */
- 	sector_t last_position;
-@@ -621,15 +619,6 @@ struct bfq_data {
- 	struct bfq_queue *bio_bfqq;
- 	/* Extra flag used only for TESTING */
- 	bool bio_bfqq_set;
--
--	/*
--	 * io context to put right after bfqd->lock is released. This
--	 * filed is used to perform put_io_context, when needed, to
--	 * after the scheduler lock has been released, and thus
--	 * prevent an ioc->lock from being possibly taken while the
--	 * scheduler lock is being held.
--	 */
--	struct io_context *ioc_to_put;
- };
- 
- enum bfqq_state_flags {
-diff --git a/block/bfq-sched.c b/block/bfq-sched.c
-index 85e59eeb3569..9c4e6797d8c9 100644
---- a/block/bfq-sched.c
-+++ b/block/bfq-sched.c
-@@ -1904,23 +1904,6 @@ static void __bfq_bfqd_reset_in_service(struct bfq_data *bfqd)
- 	struct bfq_entity *in_serv_entity = &in_serv_bfqq->entity;
- 	struct bfq_entity *entity = in_serv_entity;
- 
--	if (bfqd->in_service_bic) {
--#ifdef BFQ_MQ
--		BUG_ON(bfqd->ioc_to_put);
--		/*
--		 * Schedule the release of a reference to
--		 * bfqd->in_service_bic->icq.ioc to right after the
--		 * scheduler lock is released. This ioc is not
--		 * released immediately, to not risk to possibly take
--		 * an ioc->lock while holding the scheduler lock.
--		 */
--		bfqd->ioc_to_put = bfqd->in_service_bic->icq.ioc;
--#else
--		put_io_context(bfqd->in_service_bic->icq.ioc);
--#endif
--		bfqd->in_service_bic = NULL;
--	}
--
- 	bfq_clear_bfqq_wait_request(in_serv_bfqq);
- 	hrtimer_try_to_cancel(&bfqd->idle_slice_timer);
- 	bfqd->in_service_queue = NULL;
-
-From 1521ad11f8684cf0a1b7249249cd406fee50da6d Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Wed, 29 Mar 2017 18:41:46 +0200
-Subject: [PATCH 23/51] BUGFIX: Remove unneeded and deadlock-causing lock in
- request_merged
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-mq-iosched.c | 2 --
- 1 file changed, 2 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 8e7589d3280f..bb046335ff4f 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -1761,7 +1761,6 @@ static void bfq_request_merged(struct request_queue *q, struct request *req,
- 		BUG_ON(RQ_BFQQ(req) != bfqq);
- 		elv_rb_add(&bfqq->sort_list, req);
- 
--		spin_lock_irq(&bfqd->lock);
- 		/* Choose next request to be served for bfqq */
- 		prev = bfqq->next_rq;
- 		next_rq = bfq_choose_req(bfqd, bfqq->next_rq, req,
-@@ -1783,7 +1782,6 @@ static void bfq_request_merged(struct request_queue *q, struct request *req,
- 			bfq_updated_next_req(bfqd, bfqq);
- 			bfq_pos_tree_add_move(bfqd, bfqq);
- 		}
--		spin_unlock_irq(&bfqd->lock);
- 	}
- }
- 
-
-From 9136b4c953918ea937254c57cfb787b55b5bc2c6 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Wed, 29 Mar 2017 18:55:30 +0200
-Subject: [PATCH 24/51] Fix wrong unlikely
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-mq-iosched.c | 2 +-
- 1 file changed, 1 insertion(+), 1 deletion(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index bb046335ff4f..3ae9bd424b3f 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -4917,7 +4917,7 @@ static int bfq_get_rq_private(struct request_queue *q, struct request *rq,
- 	bfqq = bfq_get_bfqq_handle_split(bfqd, bic, bio, false, is_sync,
- 					 &new_queue);
- 
--	if (unlikely(!new_queue)) {
-+	if (likely(!new_queue)) {
- 		/* If the queue was seeky for too long, break it apart. */
- 		if (bfq_bfqq_coop(bfqq) && bfq_bfqq_split_coop(bfqq)) {
- 			BUG_ON(!is_sync);
-
-From 8e05f722f19645f2278f6962368ca3b7c2a81c9c Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Fri, 12 May 2017 09:51:18 +0200
-Subject: [PATCH 25/51] Change cgroup params prefix to bfq-mq for bfq-mq
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-cgroup-included.c | 54 ++++++++++++++++++++++++++-------------------
- 1 file changed, 31 insertions(+), 23 deletions(-)
-
-diff --git a/block/bfq-cgroup-included.c b/block/bfq-cgroup-included.c
-index dfacca799b5e..9e9b0a09e26f 100644
---- a/block/bfq-cgroup-included.c
-+++ b/block/bfq-cgroup-included.c
-@@ -995,9 +995,15 @@ bfq_create_group_hierarchy(struct bfq_data *bfqd, int node)
- 	return blkg_to_bfqg(bfqd->queue->root_blkg);
- }
- 
-+#ifdef BFQ_MQ
-+#define BFQ_CGROUP_FNAME(param) "bfq-mq."#param
-+#else
-+#define BFQ_CGROUP_FNAME(param) "bfq."#param
-+#endif
-+
- static struct cftype bfq_blkcg_legacy_files[] = {
- 	{
--		.name = "bfq.weight",
-+		.name = BFQ_CGROUP_FNAME(weight),
- 		.flags = CFTYPE_NOT_ON_ROOT,
- 		.seq_show = bfq_io_show_weight,
- 		.write_u64 = bfq_io_set_weight_legacy,
-@@ -1005,106 +1011,106 @@ static struct cftype bfq_blkcg_legacy_files[] = {
- 
- 	/* statistics, covers only the tasks in the bfqg */
- 	{
--		.name = "bfq.time",
-+		.name = BFQ_CGROUP_FNAME(time),
- 		.private = offsetof(struct bfq_group, stats.time),
- 		.seq_show = bfqg_print_stat,
- 	},
- 	{
--		.name = "bfq.sectors",
-+		.name = BFQ_CGROUP_FNAME(sectors),
- 		.seq_show = bfqg_print_stat_sectors,
- 	},
- 	{
--		.name = "bfq.io_service_bytes",
-+		.name = BFQ_CGROUP_FNAME(io_service_bytes),
- 		.private = (unsigned long)&blkcg_policy_bfq,
- 		.seq_show = blkg_print_stat_bytes,
- 	},
- 	{
--		.name = "bfq.io_serviced",
-+		.name = BFQ_CGROUP_FNAME(io_serviced),
- 		.private = (unsigned long)&blkcg_policy_bfq,
- 		.seq_show = blkg_print_stat_ios,
- 	},
- 	{
--		.name = "bfq.io_service_time",
-+		.name = BFQ_CGROUP_FNAME(io_service_time),
- 		.private = offsetof(struct bfq_group, stats.service_time),
- 		.seq_show = bfqg_print_rwstat,
- 	},
- 	{
--		.name = "bfq.io_wait_time",
-+		.name = BFQ_CGROUP_FNAME(io_wait_time),
- 		.private = offsetof(struct bfq_group, stats.wait_time),
- 		.seq_show = bfqg_print_rwstat,
- 	},
- 	{
--		.name = "bfq.io_merged",
-+		.name = BFQ_CGROUP_FNAME(io_merged),
- 		.private = offsetof(struct bfq_group, stats.merged),
- 		.seq_show = bfqg_print_rwstat,
- 	},
- 	{
--		.name = "bfq.io_queued",
-+		.name = BFQ_CGROUP_FNAME(io_queued),
- 		.private = offsetof(struct bfq_group, stats.queued),
- 		.seq_show = bfqg_print_rwstat,
- 	},
- 
- 	/* the same statictics which cover the bfqg and its descendants */
- 	{
--		.name = "bfq.time_recursive",
-+		.name = BFQ_CGROUP_FNAME(time_recursive),
- 		.private = offsetof(struct bfq_group, stats.time),
- 		.seq_show = bfqg_print_stat_recursive,
- 	},
- 	{
--		.name = "bfq.sectors_recursive",
-+		.name = BFQ_CGROUP_FNAME(sectors_recursive),
- 		.seq_show = bfqg_print_stat_sectors_recursive,
- 	},
- 	{
--		.name = "bfq.io_service_bytes_recursive",
-+		.name = BFQ_CGROUP_FNAME(io_service_bytes_recursive),
- 		.private = (unsigned long)&blkcg_policy_bfq,
- 		.seq_show = blkg_print_stat_bytes_recursive,
- 	},
- 	{
--		.name = "bfq.io_serviced_recursive",
-+		.name = BFQ_CGROUP_FNAME(io_serviced_recursive),
- 		.private = (unsigned long)&blkcg_policy_bfq,
- 		.seq_show = blkg_print_stat_ios_recursive,
- 	},
- 	{
--		.name = "bfq.io_service_time_recursive",
-+		.name = BFQ_CGROUP_FNAME(io_service_time_recursive),
- 		.private = offsetof(struct bfq_group, stats.service_time),
- 		.seq_show = bfqg_print_rwstat_recursive,
- 	},
- 	{
--		.name = "bfq.io_wait_time_recursive",
-+		.name = BFQ_CGROUP_FNAME(io_wait_time_recursive),
- 		.private = offsetof(struct bfq_group, stats.wait_time),
- 		.seq_show = bfqg_print_rwstat_recursive,
- 	},
- 	{
--		.name = "bfq.io_merged_recursive",
-+		.name = BFQ_CGROUP_FNAME(io_merged_recursive),
- 		.private = offsetof(struct bfq_group, stats.merged),
- 		.seq_show = bfqg_print_rwstat_recursive,
- 	},
- 	{
--		.name = "bfq.io_queued_recursive",
-+		.name = BFQ_CGROUP_FNAME(io_queued_recursive),
- 		.private = offsetof(struct bfq_group, stats.queued),
- 		.seq_show = bfqg_print_rwstat_recursive,
- 	},
- 	{
--		.name = "bfq.avg_queue_size",
-+		.name = BFQ_CGROUP_FNAME(avg_queue_size),
- 		.seq_show = bfqg_print_avg_queue_size,
- 	},
- 	{
--		.name = "bfq.group_wait_time",
-+		.name = BFQ_CGROUP_FNAME(group_wait_time),
- 		.private = offsetof(struct bfq_group, stats.group_wait_time),
- 		.seq_show = bfqg_print_stat,
- 	},
- 	{
--		.name = "bfq.idle_time",
-+		.name = BFQ_CGROUP_FNAME(idle_time),
- 		.private = offsetof(struct bfq_group, stats.idle_time),
- 		.seq_show = bfqg_print_stat,
- 	},
- 	{
--		.name = "bfq.empty_time",
-+		.name = BFQ_CGROUP_FNAME(empty_time),
- 		.private = offsetof(struct bfq_group, stats.empty_time),
- 		.seq_show = bfqg_print_stat,
- 	},
- 	{
--		.name = "bfq.dequeue",
-+		.name = BFQ_CGROUP_FNAME(dequeue),
- 		.private = offsetof(struct bfq_group, stats.dequeue),
- 		.seq_show = bfqg_print_stat,
- 	},
-@@ -1113,7 +1119,7 @@ static struct cftype bfq_blkcg_legacy_files[] = {
- 
- static struct cftype bfq_blkg_files[] = {
- 	{
--		.name = "bfq.weight",
-+		.name = BFQ_CGROUP_FNAME(weight),
- 		.flags = CFTYPE_NOT_ON_ROOT,
- 		.seq_show = bfq_io_show_weight,
- 		.write = bfq_io_set_weight,
-@@ -1121,6 +1127,8 @@ static struct cftype bfq_blkg_files[] = {
- 	{} /* terminate */
- };
- 
-+#undef BFQ_CGROUP_FNAME
-+
- #else /* BFQ_GROUP_IOSCHED_ENABLED */
- 
- static inline void bfqg_stats_update_io_add(struct bfq_group *bfqg,
-
-From abdf7565dadbb00e78be5f4fb2cc9b157649840e Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Fri, 12 May 2017 11:56:13 +0200
-Subject: [PATCH 26/51] Add tentative extra tests on groups, reqs and queues
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-cgroup-included.c | 1 +
- block/bfq-mq-iosched.c      | 5 +++++
- include/linux/blkdev.h      | 2 ++
- 3 files changed, 8 insertions(+)
-
-diff --git a/block/bfq-cgroup-included.c b/block/bfq-cgroup-included.c
-index 9e9b0a09e26f..72107ad12220 100644
---- a/block/bfq-cgroup-included.c
-+++ b/block/bfq-cgroup-included.c
-@@ -412,6 +412,7 @@ static void bfq_pd_init(struct blkg_policy_data *pd)
- 	BUG_ON(!blkg);
- 	bfqg = blkg_to_bfqg(blkg);
- 	bfqd = blkg->q->elevator->elevator_data;
-+	BUG_ON(bfqg == bfqd->root_group);
- 	entity = &bfqg->entity;
- 	d = blkcg_to_bfqgd(blkg->blkcg);
- 
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 3ae9bd424b3f..a9e3406fef06 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -4494,6 +4494,7 @@ static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- static void __bfq_insert_request(struct bfq_data *bfqd, struct request *rq)
- {
- 	struct bfq_queue *bfqq = RQ_BFQQ(rq), *new_bfqq;
-+	BUG_ON(!bfqq);
- 
- 	assert_spin_locked(&bfqd->lock);
- 
-@@ -4587,6 +4588,9 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
- 				"insert_request %p in disp: at_head %d",
- 				rq, at_head);
- 	} else {
-+		BUG_ON(!(rq->rq_flags & RQF_GOT));
-+		rq->rq_flags &= ~RQF_GOT;
-+
- 		__bfq_insert_request(bfqd, rq);
- 
- 		if (rq_mergeable(rq)) {
-@@ -4974,6 +4978,7 @@ static int bfq_get_rq_private(struct request_queue *q, struct request *rq,
- 	if (unlikely(bfq_bfqq_just_created(bfqq)))
- 		bfq_handle_burst(bfqd, bfqq);
- 
-+	rq->rq_flags |= RQF_GOT;
- 	spin_unlock_irq(&bfqd->lock);
- 
- 	return 0;
-diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
-index 0048e59e6d07..9ae814743095 100644
---- a/include/linux/blkdev.h
-+++ b/include/linux/blkdev.h
-@@ -123,6 +123,8 @@ typedef __u32 __bitwise req_flags_t;
- #define RQF_SPECIAL_PAYLOAD	((__force req_flags_t)(1 << 18))
- /* DEBUG: rq in bfq-mq dispatch list */
- #define RQF_DISP_LIST	((__force req_flags_t)(1 << 19))
-+/* DEBUG: rq had get_rq_private executed on it */
-+#define RQF_GOT	((__force req_flags_t)(1 << 20))
- 
- /* flags that prevent us from merging requests: */
- #define RQF_NOMERGE_FLAGS \
-
-From 9e1c1514bc947c4e04502331372b1cc58459d8d1 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Mon, 15 May 2017 22:25:03 +0200
-Subject: [PATCH 27/51] block, bfq-mq: access and cache blkg data only when
- safe
-
-In blk-cgroup, operations on blkg objects are protected with the
-request_queue lock. This is no more the lock that protects
-I/O-scheduler operations in blk-mq. In fact, the latter are now
-protected with a finer-grained per-scheduler-instance lock. As a
-consequence, although blkg lookups are also rcu-protected, blk-mq I/O
-schedulers may see inconsistent data when they access blkg and
-blkg-related objects. BFQ does access these objects, and does incur
-this problem, in the following case.
-
-The blkg_lookup performed in bfq_get_queue, being protected (only)
-through rcu, may happen to return the address of a copy of the
-original blkg. If this is the case, then the blkg_get performed in
-bfq_get_queue, to pin down the blkg, is useless: it does not prevent
-blk-cgroup code from destroying both the original blkg and all objects
-directly or indirectly referred by the copy of the blkg. BFQ accesses
-these objects, which typically causes a crash for NULL-pointer
-dereference of memory-protection violation.
-
-Some additional protection mechanism should be added to blk-cgroup to
-address this issue. In the meantime, this commit provides a quick
-temporary fix for BFQ: cache (when safe) blkg data that might
-disappear right after a blkg_lookup.
-
-In particular, this commit exploits the following facts to achieve its
-goal without introducing further locks.  Destroy operations on a blkg
-invoke, as a first step, hooks of the scheduler associated with the
-blkg. And these hooks are executed with bfqd->lock held for BFQ. As a
-consequence, for any blkg associated with the request queue an
-instance of BFQ is attached to, we are guaranteed that such a blkg is
-not destroyed, and that all the pointers it contains are consistent,
-while that instance is holding its bfqd->lock. A blkg_lookup performed
-with bfqd->lock held then returns a fully consistent blkg, which
-remains consistent until this lock is held. In more detail, this holds
-even if the returned blkg is a copy of the original one.
-
-Finally, also the object describing a group inside BFQ needs to be
-protected from destruction on the blkg_free of the original blkg
-(which invokes bfq_pd_free). This commit adds private refcounting for
-this object, to let it disappear only after no bfq_queue refers to it
-any longer.
-
-This commit also removes or updates some stale comments on locking
-issues related to blk-cgroup operations.
-
-Reported-by: Tomas Konir <tomas.konir@gmail.com>
-Reported-by: Lee Tibbert <lee.tibbert@gmail.com>
-Reported-by: Marco Piazza <mpiazza@gmail.com>
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
-Tested-by: Tomas Konir <tomas.konir@gmail.com>
-Tested-by: Lee Tibbert <lee.tibbert@gmail.com>
-Tested-by: Marco Piazza <mpiazza@gmail.com>
----
- block/bfq-cgroup-included.c | 149 ++++++++++++++++++++++++++++++++++++++++----
- block/bfq-mq-iosched.c      |   2 +-
- block/bfq-mq.h              |  26 +++-----
- 3 files changed, 148 insertions(+), 29 deletions(-)
-
-diff --git a/block/bfq-cgroup-included.c b/block/bfq-cgroup-included.c
-index 72107ad12220..d903393ee78a 100644
---- a/block/bfq-cgroup-included.c
-+++ b/block/bfq-cgroup-included.c
-@@ -43,7 +43,11 @@ BFQG_FLAG_FNS(idling)
- BFQG_FLAG_FNS(empty)
- #undef BFQG_FLAG_FNS
- 
-+#ifdef BFQ_MQ
-+/* This should be called with the scheduler lock held. */
-+#else
- /* This should be called with the queue_lock held. */
-+#endif
- static void bfqg_stats_update_group_wait_time(struct bfqg_stats *stats)
- {
- 	unsigned long long now;
-@@ -58,7 +62,11 @@ static void bfqg_stats_update_group_wait_time(struct bfqg_stats *stats)
- 	bfqg_stats_clear_waiting(stats);
- }
- 
-+#ifdef BFQ_MQ
-+/* This should be called with the scheduler lock held. */
-+#else
- /* This should be called with the queue_lock held. */
-+#endif
- static void bfqg_stats_set_start_group_wait_time(struct bfq_group *bfqg,
- 						 struct bfq_group *curr_bfqg)
- {
-@@ -72,7 +80,11 @@ static void bfqg_stats_set_start_group_wait_time(struct bfq_group *bfqg,
- 	bfqg_stats_mark_waiting(stats);
- }
- 
-+#ifdef BFQ_MQ
-+/* This should be called with the scheduler lock held. */
-+#else
- /* This should be called with the queue_lock held. */
-+#endif
- static void bfqg_stats_end_empty_time(struct bfqg_stats *stats)
- {
- 	unsigned long long now;
-@@ -198,14 +210,43 @@ static struct bfq_group *bfqq_group(struct bfq_queue *bfqq)
- 
- static void bfqg_get(struct bfq_group *bfqg)
- {
--	return blkg_get(bfqg_to_blkg(bfqg));
-+#ifdef BFQ_MQ
-+	bfqg->ref++;
-+#else
-+	blkg_get(bfqg_to_blkg(bfqg));
-+#endif
- }
- 
- static void bfqg_put(struct bfq_group *bfqg)
- {
--	return blkg_put(bfqg_to_blkg(bfqg));
-+#ifdef BFQ_MQ
-+	bfqg->ref--;
-+
-+	BUG_ON(bfqg->ref < 0);
-+	if (bfqg->ref == 0)
-+		kfree(bfqg);
-+#else
-+	blkg_put(bfqg_to_blkg(bfqg));
-+#endif
-+}
-+
-+#ifdef BFQ_MQ
-+static void bfqg_and_blkg_get(struct bfq_group *bfqg)
-+{
-+	/* see comments in bfq_bic_update_cgroup for why refcounting bfqg */
-+	bfqg_get(bfqg);
-+
-+	blkg_get(bfqg_to_blkg(bfqg));
- }
- 
-+static void bfqg_and_blkg_put(struct bfq_group *bfqg)
-+{
-+	bfqg_put(bfqg);
-+
-+	blkg_put(bfqg_to_blkg(bfqg));
-+}
-+#endif
-+
- static void bfqg_stats_update_io_add(struct bfq_group *bfqg,
- 				     struct bfq_queue *bfqq,
- 				     unsigned int op)
-@@ -310,7 +351,15 @@ static void bfq_init_entity(struct bfq_entity *entity,
- 	if (bfqq) {
- 		bfqq->ioprio = bfqq->new_ioprio;
- 		bfqq->ioprio_class = bfqq->new_ioprio_class;
-+#ifdef BFQ_MQ
-+		/*
-+		 * Make sure that bfqg and its associated blkg do not
-+		 * disappear before entity.
-+		 */
-+		bfqg_and_blkg_get(bfqg);
-+#else
- 		bfqg_get(bfqg);
-+#endif
- 	}
- 	entity->parent = bfqg->my_entity; /* NULL for root group */
- 	entity->sched_data = &bfqg->sched_data;
-@@ -397,6 +446,10 @@ static struct blkg_policy_data *bfq_pd_alloc(gfp_t gfp, int node)
- 		return NULL;
- 	}
- 
-+#ifdef BFQ_MQ
-+	/* see comments in bfq_bic_update_cgroup for why refcounting */
-+	bfqg_get(bfqg);
-+#endif
- 	return &bfqg->pd;
- }
- 
-@@ -432,7 +485,11 @@ static void bfq_pd_free(struct blkg_policy_data *pd)
- 	struct bfq_group *bfqg = pd_to_bfqg(pd);
- 
- 	bfqg_stats_exit(&bfqg->stats);
--	return kfree(bfqg);
-+#ifdef BFQ_MQ
-+	bfqg_put(bfqg);
-+#else
-+	kfree(bfqg);
-+#endif
- }
- 
- static void bfq_pd_reset_stats(struct blkg_policy_data *pd)
-@@ -516,9 +573,16 @@ static void bfq_bfqq_expire(struct bfq_data *bfqd,
-  * Move @bfqq to @bfqg, deactivating it from its old group and reactivating
-  * it on the new one.  Avoid putting the entity on the old group idle tree.
-  *
-+#ifdef BFQ_MQ
-+ * Must be called under the scheduler lock, to make sure that the blkg
-+ * owning @bfqg does not disappear (see comments in
-+ * bfq_bic_update_cgroup on guaranteeing the consistency of blkg
-+ * objects).
-+#else
-  * Must be called under the queue lock; the cgroup owning @bfqg must
-  * not disappear (by now this just means that we are called under
-  * rcu_read_lock()).
-+#endif
-  */
- static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 			  struct bfq_group *bfqg)
-@@ -555,16 +619,20 @@ static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 		       entity->tree);
- 		bfq_put_idle_entity(bfq_entity_service_tree(entity), entity);
- 	}
-+#ifdef BFQ_MQ
-+	bfqg_and_blkg_put(bfqq_group(bfqq));
-+#else
- 	bfqg_put(bfqq_group(bfqq));
-+#endif
- 
--	/*
--	 * Here we use a reference to bfqg.  We don't need a refcounter
--	 * as the cgroup reference will not be dropped, so that its
--	 * destroy() callback will not be invoked.
--	 */
- 	entity->parent = bfqg->my_entity;
- 	entity->sched_data = &bfqg->sched_data;
-+#ifdef BFQ_MQ
-+	/* pin down bfqg and its associated blkg  */
-+	bfqg_and_blkg_get(bfqg);
-+#else
- 	bfqg_get(bfqg);
-+#endif
- 
- 	BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list) && bfq_bfqq_busy(bfqq));
- 	if (bfq_bfqq_busy(bfqq)) {
-@@ -585,8 +653,14 @@ static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-  * @bic: the bic to move.
-  * @blkcg: the blk-cgroup to move to.
-  *
-+#ifdef BFQ_MQ
-+ * Move bic to blkcg, assuming that bfqd->lock is held; which makes
-+ * sure that the reference to cgroup is valid across the call (see
-+ * comments in bfq_bic_update_cgroup on this issue)
-+#else
-  * Move bic to blkcg, assuming that bfqd->queue is locked; the caller
-  * has to make sure that the reference to cgroup is valid across the call.
-+#endif
-  *
-  * NOTE: an alternative approach might have been to store the current
-  * cgroup in bfqq and getting a reference to it, reducing the lookup
-@@ -645,6 +719,59 @@ static void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio)
- 		goto out;
- 
- 	bfqg = __bfq_bic_change_cgroup(bfqd, bic, bio_blkcg(bio));
-+#ifdef BFQ_MQ
-+	/*
-+	 * Update blkg_path for bfq_log_* functions. We cache this
-+	 * path, and update it here, for the following
-+	 * reasons. Operations on blkg objects in blk-cgroup are
-+	 * protected with the request_queue lock, and not with the
-+	 * lock that protects the instances of this scheduler
-+	 * (bfqd->lock). This exposes BFQ to the following sort of
-+	 * race.
-+	 *
-+	 * The blkg_lookup performed in bfq_get_queue, protected
-+	 * through rcu, may happen to return the address of a copy of
-+	 * the original blkg. If this is the case, then the
-+	 * bfqg_and_blkg_get performed in bfq_get_queue, to pin down
-+	 * the blkg, is useless: it does not prevent blk-cgroup code
-+	 * from destroying both the original blkg and all objects
-+	 * directly or indirectly referred by the copy of the
-+	 * blkg.
-+	 *
-+	 * On the bright side, destroy operations on a blkg invoke, as
-+	 * a first step, hooks of the scheduler associated with the
-+	 * blkg. And these hooks are executed with bfqd->lock held for
-+	 * BFQ. As a consequence, for any blkg associated with the
-+	 * request queue this instance of the scheduler is attached
-+	 * to, we are guaranteed that such a blkg is not destroyed, and
-+	 * that all the pointers it contains are consistent, while we
-+	 * are holding bfqd->lock. A blkg_lookup performed with
-+	 * bfqd->lock held then returns a fully consistent blkg, which
-+	 * remains consistent until this lock is held.
-+	 *
-+	 * Thanks to the last fact, and to the fact that: (1) bfqg has
-+	 * been obtained through a blkg_lookup in the above
-+	 * assignment, and (2) bfqd->lock is being held, here we can
-+	 * safely use the policy data for the involved blkg (i.e., the
-+	 * field bfqg->pd) to get to the blkg associated with bfqg,
-+	 * and then we can safely use any field of blkg. After we
-+	 * release bfqd->lock, even just getting blkg through this
-+	 * bfqg may cause dangling references to be traversed, as
-+	 * bfqg->pd may not exist any more.
-+	 *
-+	 * In view of the above facts, here we cache, in the bfqg, any
-+	 * blkg data we may need for this bic, and for its associated
-+	 * bfq_queue. As of now, we need to cache only the path of the
-+	 * blkg, which is used in the bfq_log_* functions.
-+	 *
-+	 * Finally, note that bfqg itself needs to be protected from
-+	 * destruction on the blkg_free of the original blkg (which
-+	 * invokes bfq_pd_free). We use an additional private
-+	 * refcounter for bfqg, to let it disappear only after no
-+	 * bfq_queue refers to it any longer.
-+	 */
-+	blkg_path(bfqg_to_blkg(bfqg), bfqg->blkg_path, sizeof(bfqg->blkg_path));
-+#endif
- 	bic->blkcg_serial_nr = serial_nr;
- out:
- 	rcu_read_unlock();
-@@ -682,8 +809,6 @@ static void bfq_reparent_leaf_entity(struct bfq_data *bfqd,
-  * @bfqd: the device data structure with the root group.
-  * @bfqg: the group to move from.
-  * @st: the service tree with the entities.
-- *
-- * Needs queue_lock to be taken and reference to be valid over the call.
-  */
- static void bfq_reparent_active_entities(struct bfq_data *bfqd,
- 					 struct bfq_group *bfqg,
-@@ -736,6 +861,7 @@ static void bfq_pd_offline(struct blkg_policy_data *pd)
- #ifdef BFQ_MQ
- 	spin_lock_irqsave(&bfqd->lock, flags);
- #endif
-+
- 	/*
- 	 * Empty all service_trees belonging to this group before
- 	 * deactivating the group itself.
-@@ -746,8 +872,7 @@ static void bfq_pd_offline(struct blkg_policy_data *pd)
- 		/*
- 		 * The idle tree may still contain bfq_queues belonging
- 		 * to exited task because they never migrated to a different
--		 * cgroup from the one being destroyed now.  No one else
--		 * can access them so it's safe to act without any lock.
-+		 * cgroup from the one being destroyed now.
- 		 */
- 		bfq_flush_idle_tree(st);
- 
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index a9e3406fef06..4eb668eeacdc 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -4073,7 +4073,7 @@ static void bfq_put_queue(struct bfq_queue *bfqq)
- 
- 	kmem_cache_free(bfq_pool, bfqq);
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
--	bfqg_put(bfqg);
-+	bfqg_and_blkg_put(bfqg);
- #endif
- }
- 
-diff --git a/block/bfq-mq.h b/block/bfq-mq.h
-index 36ee24a87dda..77ab0f22ed22 100644
---- a/block/bfq-mq.h
-+++ b/block/bfq-mq.h
-@@ -695,23 +695,17 @@ static struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
- static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
- 
- #define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	do {			\
--	char __pbuf[128];						\
--									\
--	blkg_path(bfqg_to_blkg(bfqq_group(bfqq)), __pbuf, sizeof(__pbuf)); \
- 	pr_crit("%s bfq%d%c %s " fmt "\n", 				\
- 		checked_dev_name((bfqd)->queue->backing_dev_info->dev),	\
- 		(bfqq)->pid,						\
- 		bfq_bfqq_sync((bfqq)) ? 'S' : 'A',			\
--		__pbuf, ##args);					\
-+		bfqq_group(bfqq)->blkg_path, ##args);			\
- } while (0)
- 
- #define bfq_log_bfqg(bfqd, bfqg, fmt, args...)	do {			\
--	char __pbuf[128];						\
--									\
--	blkg_path(bfqg_to_blkg(bfqg), __pbuf, sizeof(__pbuf));		\
- 	pr_crit("%s %s " fmt "\n",					\
- 	checked_dev_name((bfqd)->queue->backing_dev_info->dev),		\
--	__pbuf, ##args);						\
-+	bfqg->blkg_path, ##args);					\
- } while (0)
- 
- #else /* BFQ_GROUP_IOSCHED_ENABLED */
-@@ -736,20 +730,14 @@ static struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
- static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
- 
- #define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	do {			\
--	char __pbuf[128];						\
--									\
--	blkg_path(bfqg_to_blkg(bfqq_group(bfqq)), __pbuf, sizeof(__pbuf)); \
- 	blk_add_trace_msg((bfqd)->queue, "bfq%d%c %s " fmt, \
- 			  (bfqq)->pid,			  \
- 			  bfq_bfqq_sync((bfqq)) ? 'S' : 'A',	\
--			  __pbuf, ##args);				\
-+			  bfqq_group(bfqq)->blkg_path, ##args);		\
- } while (0)
- 
- #define bfq_log_bfqg(bfqd, bfqg, fmt, args...)	do {			\
--	char __pbuf[128];						\
--									\
--	blkg_path(bfqg_to_blkg(bfqg), __pbuf, sizeof(__pbuf));		\
--	blk_add_trace_msg((bfqd)->queue, "%s " fmt, __pbuf, ##args);	\
-+	blk_add_trace_msg((bfqd)->queue, "%s " fmt, bfqg->blkg_path, ##args);\
- } while (0)
- 
- #else /* BFQ_GROUP_IOSCHED_ENABLED */
-@@ -860,6 +848,12 @@ struct bfq_group {
- 	/* must be the first member */
- 	struct blkg_policy_data pd;
- 
-+	/* cached path for this blkg (see comments in bfq_bic_update_cgroup) */
-+	char blkg_path[128];
-+
-+	/* reference counter (see comments in bfq_bic_update_cgroup) */
-+	int ref;
-+
- 	struct bfq_entity entity;
- 	struct bfq_sched_data sched_data;
- 
-
-From c9137b749aceef6c2dde88e99b2fc978d5952e76 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Sat, 17 Jun 2017 11:18:11 +0200
-Subject: [PATCH 28/51] bfq-mq: fix macro name in conditional invocation of
- policy_unregister
-
-This commit fixes the name of the macro in the conditional group that
-invokes blkcg_policy_unregister in bfq_exit for bfq-mq. Because of
-this error, blkcg_policy_unregister was never invoked.
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-mq-iosched.c | 2 +-
- 1 file changed, 1 insertion(+), 1 deletion(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 4eb668eeacdc..bc1de3f70ea8 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -5669,7 +5669,7 @@ static int __init bfq_init(void)
- static void __exit bfq_exit(void)
- {
- 	elv_unregister(&iosched_bfq_mq);
--#ifdef CONFIG_BFQ_GROUP_ENABLED
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	blkcg_policy_unregister(&blkcg_policy_bfq);
- #endif
- 	bfq_slab_kill();
-
-From c7ceb37496f63b2dba4d06946ab85ec97b87bfb5 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Wed, 5 Jul 2017 11:48:17 +0200
-Subject: [PATCH 29/51] Port of "blk-mq-sched: unify request finished methods"
-
-No need to have two different callouts of bfq vs kyber.
-
-Signed-off-by: Christoph Hellwig <hch@lst.de>
-Signed-off-by: Jens Axboe <axboe@kernel.dk>
----
- block/bfq-mq-iosched.c | 6 +++---
- 1 file changed, 3 insertions(+), 3 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index bc1de3f70ea8..2598602a0b10 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -4753,7 +4753,7 @@ static void bfq_put_rq_priv_body(struct bfq_queue *bfqq)
- 	bfq_put_queue(bfqq);
- }
- 
--static void bfq_put_rq_private(struct request_queue *q, struct request *rq)
-+static void bfq_finish_request(struct request *rq)
- {
- 	struct bfq_queue *bfqq;
- 	struct bfq_data *bfqd;
-@@ -4814,7 +4814,7 @@ static void bfq_put_rq_private(struct request_queue *q, struct request *rq)
- 
- 		assert_spin_locked(&bfqd->lock);
- 		if (!RB_EMPTY_NODE(&rq->rb_node))
--			bfq_remove_request(q, rq);
-+			bfq_remove_request(rq->q, rq);
- 		bfq_put_rq_priv_body(bfqq);
- 	}
- 
-@@ -5558,7 +5558,7 @@ static struct elv_fs_entry bfq_attrs[] = {
- static struct elevator_type iosched_bfq_mq = {
- 	.ops.mq = {
- 		.get_rq_priv		= bfq_get_rq_private,
--		.put_rq_priv		= bfq_put_rq_private,
-+		.finish_request         = bfq_finish_request,
- 		.exit_icq		= bfq_exit_icq,
- 		.insert_requests	= bfq_insert_requests,
- 		.dispatch_request	= bfq_dispatch_request,
-
-From 12bef026fe114ab5e2e284772ddc52a8be83fdbc Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Wed, 5 Jul 2017 11:54:57 +0200
-Subject: [PATCH 30/51] Port of "bfq-iosched: fix NULL ioc check in
- bfq_get_rq_private"
-
-icq_to_bic is a container_of operation, so we need to check for NULL
-before it.  Also move the check outside the spinlock while we're at
-it.
-
-Signed-off-by: Christoph Hellwig <hch@lst.de>
-Signed-off-by: Jens Axboe <axboe@kernel.dk>
----
- block/bfq-mq-iosched.c | 15 +++++----------
- 1 file changed, 5 insertions(+), 10 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 2598602a0b10..c57774a60911 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -4903,16 +4903,17 @@ static int bfq_get_rq_private(struct request_queue *q, struct request *rq,
- 			      struct bio *bio)
- {
- 	struct bfq_data *bfqd = q->elevator->elevator_data;
--	struct bfq_io_cq *bic = icq_to_bic(rq->elv.icq);
-+	struct bfq_io_cq *bic;
- 	const int is_sync = rq_is_sync(rq);
- 	struct bfq_queue *bfqq;
- 	bool bfqq_already_existing = false, split = false;
- 	bool new_queue = false;
- 
--	spin_lock_irq(&bfqd->lock);
-+	if (!rq->elv.icq)
-+		return 1;
-+	bic = icq_to_bic(rq->elv.icq);
- 
--	if (!bic)
--		goto queue_fail;
-+	spin_lock_irq(&bfqd->lock);
- 
- 	bfq_check_ioprio_change(bic, bio);
- 
-@@ -4980,13 +4981,7 @@ static int bfq_get_rq_private(struct request_queue *q, struct request *rq,
- 
- 	rq->rq_flags |= RQF_GOT;
- 	spin_unlock_irq(&bfqd->lock);
--
- 	return 0;
--
--queue_fail:
--	spin_unlock_irq(&bfqd->lock);
--
--	return 1;
- }
- 
- static void bfq_idle_slice_timer_body(struct bfq_queue *bfqq)
-
-From 633e5711347df1bf4ca935fd0aa9118a0054f75d Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Wed, 5 Jul 2017 12:02:16 +0200
-Subject: [PATCH 31/51] Port of "blk-mq-sched: unify request prepare methods"
-
-This patch makes sure we always allocate requests in the core blk-mq
-code and use a common prepare_request method to initialize them for
-both mq I/O schedulers.  For Kyber and additional limit_depth method
-is added that is called before allocating the request.
-
-Also because none of the intializations can really fail the new method
-does not return an error - instead the bfq finish method is hardened
-to deal with the no-IOC case.
-
-Last but not least this removes the abuse of RQF_QUEUE by the blk-mq
-scheduling code as RQF_ELFPRIV is all that is needed now.
-
-Signed-off-by: Christoph Hellwig <hch@lst.de>
-Signed-off-by: Jens Axboe <axboe@kernel.dk>
----
- block/bfq-mq-iosched.c | 13 ++++++++-----
- 1 file changed, 8 insertions(+), 5 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index c57774a60911..49ffca1ad6e7 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -4760,6 +4760,10 @@ static void bfq_finish_request(struct request *rq)
- 	struct bfq_io_cq *bic;
- 
- 	BUG_ON(!rq);
-+
-+	if (!rq->elv.icq)
-+		return;
-+
- 	bfqq = RQ_BFQQ(rq);
- 	BUG_ON(!bfqq);
- 
-@@ -4899,9 +4903,9 @@ static struct bfq_queue *bfq_get_bfqq_handle_split(struct bfq_data *bfqd,
- /*
-  * Allocate bfq data structures associated with this request.
-  */
--static int bfq_get_rq_private(struct request_queue *q, struct request *rq,
--			      struct bio *bio)
-+static void bfq_prepare_request(struct request *rq, struct bio *bio)
- {
-+	struct request_queue *q = rq->q;
- 	struct bfq_data *bfqd = q->elevator->elevator_data;
- 	struct bfq_io_cq *bic;
- 	const int is_sync = rq_is_sync(rq);
-@@ -4910,7 +4914,7 @@ static int bfq_get_rq_private(struct request_queue *q, struct request *rq,
- 	bool new_queue = false;
- 
- 	if (!rq->elv.icq)
--		return 1;
-+		return;
- 	bic = icq_to_bic(rq->elv.icq);
- 
- 	spin_lock_irq(&bfqd->lock);
-@@ -4981,7 +4985,6 @@ static int bfq_get_rq_private(struct request_queue *q, struct request *rq,
- 
- 	rq->rq_flags |= RQF_GOT;
- 	spin_unlock_irq(&bfqd->lock);
--	return 0;
- }
- 
- static void bfq_idle_slice_timer_body(struct bfq_queue *bfqq)
-@@ -5552,7 +5555,7 @@ static struct elv_fs_entry bfq_attrs[] = {
- 
- static struct elevator_type iosched_bfq_mq = {
- 	.ops.mq = {
--		.get_rq_priv		= bfq_get_rq_private,
-+		.prepare_request        = bfq_prepare_request,
- 		.finish_request         = bfq_finish_request,
- 		.exit_icq		= bfq_exit_icq,
- 		.insert_requests	= bfq_insert_requests,
-
-From 5a321acfce282c3e58ac63582faf6f928ad17f27 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Wed, 5 Jul 2017 12:43:22 +0200
-Subject: [PATCH 32/51] Add list of bfq instances to documentation
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- Documentation/block/bfq-iosched.txt | 11 ++++++++++-
- 1 file changed, 10 insertions(+), 1 deletion(-)
-
-diff --git a/Documentation/block/bfq-iosched.txt b/Documentation/block/bfq-iosched.txt
-index 3d6951d63489..8ce6b9a9bacd 100644
---- a/Documentation/block/bfq-iosched.txt
-+++ b/Documentation/block/bfq-iosched.txt
-@@ -11,6 +11,15 @@ controllers), BFQ's main features are:
-   groups (switching back to time distribution when needed to keep
-   throughput high).
- 
-+If bfq-mq patches have been applied, then the following three
-+instances of BFQ are available (otherwise only the first instance):
-+- bfq: mainline version of BFQ, for blk-mq
-+- bfq-mq: development version of BFQ for blk-mq; this version contains
-+   also all latest features not yet landed in mainline, plus many
-+   safety checks
-+- bfq: BFQ for legacy blk; also this version contains both latest
-+   features and safety checks
-+
- In its default configuration, BFQ privileges latency over
- throughput. So, when needed for achieving a lower latency, BFQ builds
- schedules that may lead to a lower throughput. If your main or only
-@@ -27,7 +36,7 @@ sequential I/O (e.g., 8-12 GB/s if I/O requests are 256 KB large), and
- to 120-200 MB/s with 4KB random I/O. BFQ is currently being tested on
- multi-queue devices too.
- 
--The table of contents follow. Impatients can just jump to Section 3.
-+The table of contents follows. Impatients can just jump to Section 3.
- 
- CONTENTS
- 
-
-From 9f2e5b27227fd9254cc258572dc2d4531838c30b Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Wed, 5 Jul 2017 16:28:00 +0200
-Subject: [PATCH 33/51] bfq-sq: fix prefix of names of cgroups parameters
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- Documentation/block/bfq-iosched.txt | 12 +++++++-----
- block/bfq-cgroup-included.c         |  2 +-
- 2 files changed, 8 insertions(+), 6 deletions(-)
-
-diff --git a/Documentation/block/bfq-iosched.txt b/Documentation/block/bfq-iosched.txt
-index 8ce6b9a9bacd..965d82f94db9 100644
---- a/Documentation/block/bfq-iosched.txt
-+++ b/Documentation/block/bfq-iosched.txt
-@@ -503,10 +503,12 @@ To get proportional sharing of bandwidth with BFQ for a given device,
- BFQ must of course be the active scheduler for that device.
- 
- Within each group directory, the names of the files associated with
--BFQ-specific cgroup parameters and stats begin with the "bfq."
--prefix. So, with cgroups-v1 or cgroups-v2, the full prefix for
--BFQ-specific files is "blkio.bfq." or "io.bfq." For example, the group
--parameter to set the weight of a group with BFQ is blkio.bfq.weight
-+BFQ-specific cgroup parameters and stats begin with the "bfq.",
-+"bfq-sq." or "bfq-mq." prefix, depending on which instance of bfq you
-+want to use. So, with cgroups-v1 or cgroups-v2, the full prefix for
-+BFQ-specific files is "blkio.bfqX." or "io.bfqX.", where X can be ""
-+(i.e., null string), "-sq" or "-mq". For example, the group parameter
-+to set the weight of a group with the mainline BFQ is blkio.bfq.weight
- or io.bfq.weight.
- 
- Parameters to set
-@@ -514,7 +516,7 @@ Parameters to set
- 
- For each group, there is only the following parameter to set.
- 
--weight (namely blkio.bfq.weight or io.bfq-weight): the weight of the
-+weight (namely blkio.bfqX.weight or io.bfqX.weight): the weight of the
- group inside its parent. Available values: 1..10000 (default 100). The
- linear mapping between ioprio and weights, described at the beginning
- of the tunable section, is still valid, but all weights higher than
-diff --git a/block/bfq-cgroup-included.c b/block/bfq-cgroup-included.c
-index d903393ee78a..631e53d9150d 100644
---- a/block/bfq-cgroup-included.c
-+++ b/block/bfq-cgroup-included.c
-@@ -1124,7 +1124,7 @@ bfq_create_group_hierarchy(struct bfq_data *bfqd, int node)
- #ifdef BFQ_MQ
- #define BFQ_CGROUP_FNAME(param) "bfq-mq."#param
- #else
--#define BFQ_CGROUP_FNAME(param) "bfq."#param
-+#define BFQ_CGROUP_FNAME(param) "bfq-sq."#param
- #endif
- 
- static struct cftype bfq_blkcg_legacy_files[] = {
-
-From 92b42df8166939ccf26aa450125b5b575cf6d505 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Wed, 5 Jul 2017 21:08:32 +0200
-Subject: [PATCH 34/51] Add to documentation that bfq-mq and bfq-sq contain
- last fixes too
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- Documentation/block/bfq-iosched.txt | 6 +++---
- 1 file changed, 3 insertions(+), 3 deletions(-)
-
-diff --git a/Documentation/block/bfq-iosched.txt b/Documentation/block/bfq-iosched.txt
-index 965d82f94db9..0e59f1c9d30e 100644
---- a/Documentation/block/bfq-iosched.txt
-+++ b/Documentation/block/bfq-iosched.txt
-@@ -15,10 +15,10 @@ If bfq-mq patches have been applied, then the following three
- instances of BFQ are available (otherwise only the first instance):
- - bfq: mainline version of BFQ, for blk-mq
- - bfq-mq: development version of BFQ for blk-mq; this version contains
--   also all latest features not yet landed in mainline, plus many
-+   also all latest features and fixes not yet landed in mainline, plus many
-    safety checks
--- bfq: BFQ for legacy blk; also this version contains both latest
--   features and safety checks
-+- bfq: BFQ for legacy blk; also this version contains latest features
-+   and fixes, as well as safety checks
- 
- In its default configuration, BFQ privileges latency over
- throughput. So, when needed for achieving a lower latency, BFQ builds
-
-From 7f9bdd433b848d4f53c167258bf4d0b3f1ae1923 Mon Sep 17 00:00:00 2001
-From: Lee Tibbert <lee.tibbert@gmail.com>
-Date: Wed, 19 Jul 2017 10:28:32 -0400
-Subject: [PATCH 35/51] Improve most frequently used no-logging path
-
-This patch originated as a fix for compiler unused-variable warnings
-issued when compiling bfq-mq with logging disabled (both
-CONFIG_BLK_DEV_IO_TRACE and CONFIG_BFQ_REDIRECT_TO_CONSOLE
-undefined).
-
-It turns out to also have benefits for the bfq-sq path as well.
-
-In most performance sensitive production builds blktrace_api logging
-will probably be turned off, so it is worth making the no-logging path
-compile without warnings. Any performance benefit is a bonus.
-
-Thank you to T. B. on the bfq-iosched@googlegroups.com list
-for ((void) (bfqq)) simplification/suggestion/improvement. All bugs
-and unclear descriptions are my own doing.
-
-The discussion below is based on the gcc compiler with optimization
-level of at least 02.  Lower optimization levels are unlikely to
-remove no-op instruction equivalents.
-
-Provide three improvements in this likely case.
-
-  1) Fix multiple occurrences of an unused-variable warning
-     issued when compiling bfq-mq with no logging. The warning
-     occurred each time the bfq_log_bfqg macro was expanded inside
-     a code block such as the following snippet from
-     block/bfq-sched.c, line 139 and few following, lightly edited for
-     indentation in order to pass checkpatch.pl maximum line lengths.
-
-else {
-     struct bfq_group *bfqg =
-             container_of(next_in_service,
-                     struct bfq_group, entity);
-
-     bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-             "update_next_in_service: chosen this entity");
-     }
-
-     Previously bfq-mq.h expanded bfq_log_bfqg to blk_add_trace_msg.
-     When both bfq console logging and blktrace_api logging are
-     disabled, include/linux/blktrace_api expands to
-     do { } while (0), leaving the code block local variable unused.
-
-     bfq_log_bfqq() had similar behavior but is never called with
-     a potentially unused variable. This patch fixes that macro for
-     consistency.
-
-     bfq-sq.h (single queue) with blktrace_api enabled, and the bfq
-     console logging macros have code paths which not trigger this
-     warning.
-
-     kernel.org (4.12 & 4.13) bfq (bfq-iosched.h) could trigger
-     the warning but no code does so now. This patch fixes
-     bfq-iosched.h for consistency.
-
-     The style above enables a software engineering approach where
-     complex expressions are moved to a local variable before the
-     bfq_log* call.  This makes it easier to read the expression and
-     use breakpoints to verify it. bfq-mq uses this approach in
-     several places.
-
-     New bfq_log* macros are provided for the no-logging case.
-     I touch only the second argument, because current code never
-     uses the local variable approach with the first or other
-     arguments. I tried to balance consistency with simplicity.
-
-  2) For bfq-sq, reduce to zero, the number of instructions executed
-     when no logging is configured. No sense marshaling arguments
-     which are never going to be used.
-
-     On a trial V8R11 builds, this reduced the size of bfq-iosched.o
-     by 14.3 KiB. The size went from 70304 to 55664 bytes.
-
-     bfq-mq and kernel.org bfq code size does not change because
-     existing macros already optimize to zero bytes when not logging.
-     The current changes maintains consistency with the bfq-sq path
-     and makes the bfq-mq & bfq no-logging paths resistant to future
-     logging path macro changes which might cause generated code.
-
-  3) Slightly reduce compile time of all bfq variants by including
-     blktrace_api.h only when it will be used.
-
-Signed-off-by: Lee Tibbert <lee.tibbert@gmail.com>
----
- block/bfq-mq.h | 18 +++++++++++++++++-
- block/bfq.h    | 18 +++++++++++++++++-
- 2 files changed, 34 insertions(+), 2 deletions(-)
-
-diff --git a/block/bfq-mq.h b/block/bfq-mq.h
-index 77ab0f22ed22..7ed2cc29be57 100644
---- a/block/bfq-mq.h
-+++ b/block/bfq-mq.h
-@@ -15,7 +15,6 @@
- #ifndef _BFQ_H
- #define _BFQ_H
- 
--#include <linux/blktrace_api.h>
- #include <linux/hrtimer.h>
- #include <linux/blk-cgroup.h>
- 
-@@ -725,6 +724,21 @@ static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
- 		##args)
- 
- #else /* CONFIG_BFQ_REDIRECT_TO_CONSOLE */
-+
-+#if !defined(CONFIG_BLK_DEV_IO_TRACE)
-+
-+/* Avoid possible "unused-variable" warning. See commit message. */
-+
-+#define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	((void) (bfqq))
-+
-+#define bfq_log_bfqg(bfqd, bfqg, fmt, args...)	((void) (bfqg))
-+
-+#define bfq_log(bfqd, fmt, args...)		do {} while (0)
-+
-+#else /* CONFIG_BLK_DEV_IO_TRACE */
-+
-+#include <linux/blktrace_api.h>
-+
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
- static struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
- static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
-@@ -752,6 +766,8 @@ static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
- 
- #define bfq_log(bfqd, fmt, args...) \
- 	blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args)
-+
-+#endif /* CONFIG_BLK_DEV_IO_TRACE */
- #endif /* CONFIG_BFQ_REDIRECT_TO_CONSOLE */
- 
- /* Expiration reasons. */
-diff --git a/block/bfq.h b/block/bfq.h
-index 53954d1b87f8..15d326f466b7 100644
---- a/block/bfq.h
-+++ b/block/bfq.h
-@@ -15,7 +15,6 @@
- #ifndef _BFQ_H
- #define _BFQ_H
- 
--#include <linux/blktrace_api.h>
- #include <linux/hrtimer.h>
- #include <linux/blk-cgroup.h>
- 
-@@ -725,6 +724,21 @@ static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
- 		##args)
- 
- #else /* CONFIG_BFQ_REDIRECT_TO_CONSOLE */
-+
-+#if !defined(CONFIG_BLK_DEV_IO_TRACE)
-+
-+/* Avoid possible "unused-variable" warning. See commit message. */
-+
-+#define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	((void) (bfqq))
-+
-+#define bfq_log_bfqg(bfqd, bfqg, fmt, args...)	((void) (bfqg))
-+
-+#define bfq_log(bfqd, fmt, args...)		do {} while (0)
-+
-+#else /* CONFIG_BLK_DEV_IO_TRACE */
-+
-+#include <linux/blktrace_api.h>
-+
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
- static struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
- static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
-@@ -759,6 +773,8 @@ static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
- 
- #define bfq_log(bfqd, fmt, args...) \
- 	blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args)
-+
-+#endif /* CONFIG_BLK_DEV_IO_TRACE */
- #endif /* CONFIG_BFQ_REDIRECT_TO_CONSOLE */
- 
- /* Expiration reasons. */
-
-From f11a0e751e741bf94c6a48234824d50b3c0100ad Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Wed, 9 Aug 2017 16:40:39 +0200
-Subject: [PATCH 36/51] bfq-sq: fix commit "Remove all get and put of I/O
- contexts" in branch bfq-mq
-
-The commit "Remove all get and put of I/O contexts" erroneously removed
-the reset of the field in_service_bic for bfq-sq. This commit re-adds
-that missing reset.
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-sched.c      | 7 +++++++
- block/bfq-sq-iosched.c | 1 +
- 2 files changed, 8 insertions(+)
-
-diff --git a/block/bfq-sched.c b/block/bfq-sched.c
-index 9c4e6797d8c9..7425824c26b8 100644
---- a/block/bfq-sched.c
-+++ b/block/bfq-sched.c
-@@ -1904,6 +1904,13 @@ static void __bfq_bfqd_reset_in_service(struct bfq_data *bfqd)
- 	struct bfq_entity *in_serv_entity = &in_serv_bfqq->entity;
- 	struct bfq_entity *entity = in_serv_entity;
- 
-+#ifndef BFQ_MQ
-+	if (bfqd->in_service_bic) {
-+		put_io_context(bfqd->in_service_bic->icq.ioc);
-+		bfqd->in_service_bic = NULL;
-+	}
-+#endif
-+
- 	bfq_clear_bfqq_wait_request(in_serv_bfqq);
- 	hrtimer_try_to_cancel(&bfqd->idle_slice_timer);
- 	bfqd->in_service_queue = NULL;
-diff --git a/block/bfq-sq-iosched.c b/block/bfq-sq-iosched.c
-index 25da0d1c0622..e1960bf149d8 100644
---- a/block/bfq-sq-iosched.c
-+++ b/block/bfq-sq-iosched.c
-@@ -3765,6 +3765,7 @@ static int bfq_dispatch_request(struct bfq_data *bfqd,
- 	if (!bfqd->in_service_bic) {
- 		atomic_long_inc(&RQ_BIC(rq)->icq.ioc->refcount);
- 		bfqd->in_service_bic = RQ_BIC(rq);
-+		BUG_ON(!bfqd->in_service_bic);
- 	}
- 
- 	if (bfqd->busy_queues > 1 && bfq_class_idle(bfqq))
-
-From eceae5457530df8598557767d7be258ca9384de4 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Wed, 9 Aug 2017 22:29:01 +0200
-Subject: [PATCH 37/51] bfq-sq-mq: make lookup_next_entity push up vtime on
- expirations
-
-To provide a very smooth service, bfq starts to serve a bfq_queue
-only if the queue is 'eligible', i.e., if the same queue would
-have started to be served in the ideal, perfectly fair system that
-bfq simulates internally. This is obtained by associating each
-queue with a virtual start time, and by computing a special system
-virtual time quantity: a queue is eligible only if the system
-virtual time has reached the virtual start time of the
-queue. Finally, bfq guarantees that, when a new queue must be set
-in service, there is always at least one eligible entity for each
-active parent entity in the scheduler. To provide this guarantee,
-the function __bfq_lookup_next_entity pushes up, for each parent
-entity on which it is invoked, the system virtual time to the
-minimum among the virtual start times of the entities in the
-active tree for the parent entity (more precisely, the push up
-occurs if the system virtual time happens to be lower than all
-such virtual start times).
-
-There is however a circumstance in which __bfq_lookup_next_entity
-cannot push up the system virtual time for a parent entity, even
-if the system virtual time is lower than the virtual start times
-of all the child entities in the active tree. It happens if one of
-the child entities is in service. In fact, in such a case, there
-is already an eligible entity, the in-service one, even if it may
-not be not present in the active tree (because in-service entities
-may be removed from the active tree).
-
-Unfortunately, in the last re-design of the
-hierarchical-scheduling engine, the reset of the pointer to the
-in-service entity for a given parent entity--reset to be done as a
-consequence of the expiration of the in-service entity--always
-happens after the function __bfq_lookup_next_entity has been
-invoked. This causes the function to think that there is still an
-entity in service for the parent entity, and then that the system
-virtual time cannot be pushed up, even if actually such a
-no-more-in-service entity has already been properly reinserted
-into the active tree (or in some other tree if no more
-active). Yet, the system virtual time *had* to be pushed up, to be
-ready to correctly choose the next queue to serve. Because of the
-lack of this push up, bfq may wrongly set in service a queue that
-had been speculatively pre-computed as the possible
-next-in-service queue, but that would no more be the one to serve
-after the expiration and the reinsertion into the active trees of
-the previously in-service entities.
-
-This commit addresses this issue by making
-__bfq_lookup_next_entity properly push up the system virtual time
-if an expiration is occurring.
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-mq-iosched.c |  4 +--
- block/bfq-sched.c      | 77 ++++++++++++++++++++++++++++++++------------------
- block/bfq-sq-iosched.c |  4 +--
- 3 files changed, 53 insertions(+), 32 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 49ffca1ad6e7..b5c848650375 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -682,7 +682,7 @@ static void bfq_updated_next_req(struct bfq_data *bfqd,
- 		entity->budget = new_budget;
- 		bfq_log_bfqq(bfqd, bfqq, "updated next rq: new budget %lu",
- 					 new_budget);
--		bfq_requeue_bfqq(bfqd, bfqq);
-+		bfq_requeue_bfqq(bfqd, bfqq, false);
- 	}
- }
- 
-@@ -2822,7 +2822,7 @@ static void __bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq)
- 
- 		bfq_del_bfqq_busy(bfqd, bfqq, true);
- 	} else {
--		bfq_requeue_bfqq(bfqd, bfqq);
-+		bfq_requeue_bfqq(bfqd, bfqq, true);
- 		/*
- 		 * Resort priority tree of potential close cooperators.
- 		 */
-diff --git a/block/bfq-sched.c b/block/bfq-sched.c
-index 7425824c26b8..f3001af37256 100644
---- a/block/bfq-sched.c
-+++ b/block/bfq-sched.c
-@@ -33,7 +33,8 @@ static struct bfq_entity *bfq_root_active_entity(struct rb_root *tree)
- 	return rb_entry(node, struct bfq_entity, rb_node);
- }
- 
--static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd);
-+static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd,
-+						 bool expiration);
- 
- static bool bfq_update_parent_budget(struct bfq_entity *next_in_service);
- 
-@@ -43,6 +44,8 @@ static bool bfq_update_parent_budget(struct bfq_entity *next_in_service);
-  * @new_entity: if not NULL, pointer to the entity whose activation,
-  *		requeueing or repositionig triggered the invocation of
-  *		this function.
-+ * @expiration: id true, this function is being invoked after the
-+ *		expiration of the in-service entity
-  *
-  * This function is called to update sd->next_in_service, which, in
-  * its turn, may change as a consequence of the insertion or
-@@ -61,7 +64,8 @@ static bool bfq_update_parent_budget(struct bfq_entity *next_in_service);
-  * entity.
-  */
- static bool bfq_update_next_in_service(struct bfq_sched_data *sd,
--				       struct bfq_entity *new_entity)
-+				       struct bfq_entity *new_entity,
-+				       bool expiration)
- {
- 	struct bfq_entity *next_in_service = sd->next_in_service;
- 	struct bfq_queue *bfqq;
-@@ -120,7 +124,7 @@ static bool bfq_update_next_in_service(struct bfq_sched_data *sd,
- 		if (replace_next)
- 			next_in_service = new_entity;
- 	} else /* invoked because of a deactivation: lookup needed */
--		next_in_service = bfq_lookup_next_entity(sd);
-+		next_in_service = bfq_lookup_next_entity(sd, expiration);
- 
- 	if (next_in_service) {
- 		parent_sched_may_change = !sd->next_in_service ||
-@@ -1291,10 +1295,12 @@ static void __bfq_activate_requeue_entity(struct bfq_entity *entity,
-  * @requeue: true if this is a requeue, which implies that bfqq is
-  *	     being expired; thus ALL its ancestors stop being served and must
-  *	     therefore be requeued
-+ * @expiration: true if this function is being invoked in the expiration path
-+ *		of the in-service queue
-  */
- static void bfq_activate_requeue_entity(struct bfq_entity *entity,
- 					bool non_blocking_wait_rq,
--					bool requeue)
-+					bool requeue, bool expiration)
- {
- 	struct bfq_sched_data *sd;
- 
-@@ -1307,7 +1313,8 @@ static void bfq_activate_requeue_entity(struct bfq_entity *entity,
- 		       RB_EMPTY_ROOT(&(sd->service_tree+1)->active) &&
- 		       RB_EMPTY_ROOT(&(sd->service_tree+2)->active));
- 
--		if (!bfq_update_next_in_service(sd, entity) && !requeue) {
-+		if (!bfq_update_next_in_service(sd, entity, expiration) &&
-+		    !requeue) {
- 			BUG_ON(!sd->next_in_service);
- 			break;
- 		}
-@@ -1373,6 +1380,8 @@ static bool __bfq_deactivate_entity(struct bfq_entity *entity,
-  * bfq_deactivate_entity - deactivate an entity representing a bfq_queue.
-  * @entity: the entity to deactivate.
-  * @ins_into_idle_tree: true if the entity can be put into the idle tree
-+ * @expiration: true if this function is being invoked in the expiration path
-+ *		of the in-service queue
-  */
- static void bfq_deactivate_entity(struct bfq_entity *entity,
- 				  bool ins_into_idle_tree,
-@@ -1417,7 +1426,7 @@ static void bfq_deactivate_entity(struct bfq_entity *entity,
- 			 * then, since entity has just been
- 			 * deactivated, a new one must be found.
- 			 */
--			bfq_update_next_in_service(sd, NULL);
-+			bfq_update_next_in_service(sd, NULL, expiration);
- 
- 		if (sd->next_in_service || sd->in_service_entity) {
- 			/*
-@@ -1495,7 +1504,7 @@ static void bfq_deactivate_entity(struct bfq_entity *entity,
- 				     "invoking udpdate_next for this entity");
- 		}
- #endif
--		if (!bfq_update_next_in_service(sd, entity) &&
-+		if (!bfq_update_next_in_service(sd, entity, expiration) &&
- 		    !expiration)
- 			/*
- 			 * next_in_service unchanged or not causing
-@@ -1524,7 +1533,7 @@ static u64 bfq_calc_vtime_jump(struct bfq_service_tree *st)
- 		if (bfqq)
- 			bfq_log_bfqq(bfqq->bfqd, bfqq,
- 				     "calc_vtime_jump: new value %llu",
--				     root_entity->min_start);
-+				     ((root_entity->min_start>>10)*1000)>>12);
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
- 		else {
- 			struct bfq_group *bfqg =
-@@ -1533,7 +1542,7 @@ static u64 bfq_calc_vtime_jump(struct bfq_service_tree *st)
- 
- 			bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
- 				     "calc_vtime_jump: new value %llu",
--				     root_entity->min_start);
-+				     ((root_entity->min_start>>10)*1000)>>12);
- 		}
- #endif
- 		return root_entity->min_start;
-@@ -1615,17 +1624,9 @@ static struct bfq_entity *bfq_first_active_entity(struct bfq_service_tree *st,
-  * 3) is idle.
-  */
- static struct bfq_entity *
--__bfq_lookup_next_entity(struct bfq_service_tree *st, bool in_service
--#if 0
--			 , bool force
--#endif
--	)
-+__bfq_lookup_next_entity(struct bfq_service_tree *st, bool in_service)
- {
--	struct bfq_entity *entity
--#if 0
--		, *new_next_in_service = NULL
--#endif
--		;
-+	struct bfq_entity *entity;
- 	u64 new_vtime;
- 	struct bfq_queue *bfqq;
- 
-@@ -1667,8 +1668,9 @@ __bfq_lookup_next_entity(struct bfq_service_tree *st, bool in_service
- 			container_of(entity, struct bfq_group, entity);
- 
- 		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
--			     "__lookup_next: start %llu vtime %llu st %p",
-+			     "__lookup_next: start %llu vtime %llu (%llu) st %p",
- 			     ((entity->start>>10)*1000)>>12,
-+			     ((st->vtime>>10)*1000)>>12,
- 			     ((new_vtime>>10)*1000)>>12, st);
- 	}
- #endif
-@@ -1681,12 +1683,14 @@ __bfq_lookup_next_entity(struct bfq_service_tree *st, bool in_service
- /**
-  * bfq_lookup_next_entity - return the first eligible entity in @sd.
-  * @sd: the sched_data.
-+ * @expiration: true if we are on the expiration path of the in-service queue
-  *
-  * This function is invoked when there has been a change in the trees
-- * for sd, and we need know what is the new next entity after this
-- * change.
-+ * for sd, and we need to know what is the new next entity to serve
-+ * after this change.
-  */
--static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd)
-+static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd,
-+						 bool expiration)
- {
- 	struct bfq_service_tree *st = sd->service_tree;
- 	struct bfq_service_tree *idle_class_st = st + (BFQ_IOPRIO_CLASSES - 1);
-@@ -1716,8 +1720,24 @@ static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd)
- 	 * class, unless the idle class needs to be served.
- 	 */
- 	for (; class_idx < BFQ_IOPRIO_CLASSES; class_idx++) {
-+		/*
-+		 * If expiration is true, then bfq_lookup_next_entity
-+		 * is being invoked as a part of the expiration path
-+		 * of the in-service queue. In this case, even if
-+		 * sd->in_service_entity is not NULL,
-+		 * sd->in_service_entiy at this point is actually not
-+		 * in service any more, and, if needed, has already
-+		 * been properly queued or requeued into the right
-+		 * tree. The reason why sd->in_service_entity is still
-+		 * not NULL here, even if expiration is true, is that
-+		 * sd->in_service_entiy is reset as a last step in the
-+		 * expiration path. So, if expiration is true, tell
-+		 * __bfq_lookup_next_entity that there is no
-+		 * sd->in_service_entity.
-+		 */
- 		entity = __bfq_lookup_next_entity(st + class_idx,
--						  sd->in_service_entity);
-+						  sd->in_service_entity &&
-+						  !expiration);
- 
- 		if (entity)
- 			break;
-@@ -1891,7 +1911,7 @@ static struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd)
- 	for_each_entity(entity) {
- 		struct bfq_sched_data *sd = entity->sched_data;
- 
--		if(!bfq_update_next_in_service(sd, NULL))
-+		if (!bfq_update_next_in_service(sd, NULL, false))
- 			break;
- 	}
- 
-@@ -1951,16 +1971,17 @@ static void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
- 	       entity->on_st);
- 
- 	bfq_activate_requeue_entity(entity, bfq_bfqq_non_blocking_wait_rq(bfqq),
--				    false);
-+				    false, false);
- 	bfq_clear_bfqq_non_blocking_wait_rq(bfqq);
- }
- 
--static void bfq_requeue_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+static void bfq_requeue_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+			     bool expiration)
- {
- 	struct bfq_entity *entity = &bfqq->entity;
- 
- 	bfq_activate_requeue_entity(entity, false,
--				    bfqq == bfqd->in_service_queue);
-+				    bfqq == bfqd->in_service_queue, expiration);
- }
- 
- static void bfqg_stats_update_dequeue(struct bfq_group *bfqg);
-diff --git a/block/bfq-sq-iosched.c b/block/bfq-sq-iosched.c
-index e1960bf149d8..42393ab889a9 100644
---- a/block/bfq-sq-iosched.c
-+++ b/block/bfq-sq-iosched.c
-@@ -644,7 +644,7 @@ static void bfq_updated_next_req(struct bfq_data *bfqd,
- 		entity->budget = new_budget;
- 		bfq_log_bfqq(bfqd, bfqq, "updated next rq: new budget %lu",
- 					 new_budget);
--		bfq_requeue_bfqq(bfqd, bfqq);
-+		bfq_requeue_bfqq(bfqd, bfqq, false);
- 	}
- }
- 
-@@ -2715,7 +2715,7 @@ static void __bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq)
- 
- 		bfq_del_bfqq_busy(bfqd, bfqq, true);
- 	} else {
--		bfq_requeue_bfqq(bfqd, bfqq);
-+		bfq_requeue_bfqq(bfqd, bfqq, true);
- 		/*
- 		 * Resort priority tree of potential close cooperators.
- 		 */
-
-From ee9f95b24e1d88ffba4845981c2a4684aefd0245 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Wed, 9 Aug 2017 22:53:00 +0200
-Subject: [PATCH 38/51] bfq-sq-mq: remove direct switch to an entity in higher
- class
-
-If the function bfq_update_next_in_service is invoked as a consequence
-of the activation or requeueing of an entity, say E, and finds out
-that E belongs to a higher-priority class than that of the current
-next-in-service entity, then it sets next_in_service directly to
-E. But this may lead to anomalous schedules, because E may happen not
-be eligible for service, because its virtual start time is higher than
-the system virtual time for its service tree.
-
-This commit addresses this issue by simply removing this direct
-switch.
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-sched.c | 19 +++++--------------
- 1 file changed, 5 insertions(+), 14 deletions(-)
-
-diff --git a/block/bfq-sched.c b/block/bfq-sched.c
-index f3001af37256..b1a59088db88 100644
---- a/block/bfq-sched.c
-+++ b/block/bfq-sched.c
-@@ -76,9 +76,8 @@ static bool bfq_update_next_in_service(struct bfq_sched_data *sd,
- 	 * or repositiong of an entity that does not coincide with
- 	 * sd->next_in_service, then a full lookup in the active tree
- 	 * can be avoided. In fact, it is enough to check whether the
--	 * just-modified entity has a higher priority than
--	 * sd->next_in_service, or, even if it has the same priority
--	 * as sd->next_in_service, is eligible and has a lower virtual
-+	 * just-modified entity has the same priority as
-+	 * sd->next_in_service, is eligible and has a lower virtual
- 	 * finish time than sd->next_in_service. If this compound
- 	 * condition holds, then the new entity becomes the new
- 	 * next_in_service. Otherwise no change is needed.
-@@ -94,9 +93,8 @@ static bool bfq_update_next_in_service(struct bfq_sched_data *sd,
- 
- 		/*
- 		 * If there is already a next_in_service candidate
--		 * entity, then compare class priorities or timestamps
--		 * to decide whether to replace sd->service_tree with
--		 * new_entity.
-+		 * entity, then compare timestamps to decide whether
-+		 * to replace sd->service_tree with new_entity.
- 		 */
- 		if (next_in_service) {
- 			unsigned int new_entity_class_idx =
-@@ -104,10 +102,6 @@ static bool bfq_update_next_in_service(struct bfq_sched_data *sd,
- 			struct bfq_service_tree *st =
- 				sd->service_tree + new_entity_class_idx;
- 
--			/*
--			 * For efficiency, evaluate the most likely
--			 * sub-condition first.
--			 */
- 			replace_next =
- 				(new_entity_class_idx ==
- 				 bfq_class_idx(next_in_service)
-@@ -115,10 +109,7 @@ static bool bfq_update_next_in_service(struct bfq_sched_data *sd,
- 				 !bfq_gt(new_entity->start, st->vtime)
- 				 &&
- 				 bfq_gt(next_in_service->finish,
--					new_entity->finish))
--				||
--				new_entity_class_idx <
--				bfq_class_idx(next_in_service);
-+					new_entity->finish));
- 		}
- 
- 		if (replace_next)
-
-From a3fdc5af40537355b68c1f0d3997c5a5fb54b9ce Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Thu, 10 Aug 2017 08:15:50 +0200
-Subject: [PATCH 39/51] bfq-sq-mq: guarantee update_next_in_service always
- returns an eligible entity
-
-If the function bfq_update_next_in_service is invoked as a consequence
-of the activation or requeueing of an entity, say E, then it doesn't
-invoke bfq_lookup_next_entity to get the next-in-service entity. In
-contrast, it follows a shorter path: if E happens to be eligible (see
-commit "bfq-sq-mq: make lookup_next_entity push up vtime on
-expirations" for details on eligibility) and to have a lower virtual
-finish time than the current candidate as next-in-service entity, then
-E directly becomes the next-in-service entity. Unfortunately, there is
-a corner case for which this shorter path makes
-bfq_update_next_in_service choose a non eligible entity: it occurs if
-both E and the current next-in-service entity happen to be non
-eligible when bfq_update_next_in_service is invoked. In this case, E
-is not set as next-in-service, and, since bfq_lookup_next_entity is
-not invoked, the state of the parent entity is not updated so as to
-end up with an eligible entity as the proper next-in-service entity.
-
-In this respect, next-in-service is actually allowed to be non
-eligible while some queue is in service: since no system-virtual-time
-push-up can be performed in that case (see again commit "bfq-sq-mq:
-make lookup_next_entity push up vtime on expirations" for details),
-next-in-service is chosen, speculatively, as a function of the
-possible value that the system virtual time may get after a push
-up. But the correctness of the schedule breaks if next-in-service is
-still a non eligible entity when it is time to set in service the next
-entity. Unfortunately, this may happen in the above corner case.
-
-This commit fixes this problem by making bfq_update_next_in_service
-invoke bfq_lookup_next_entity not only if the above shorter path
-cannot be taken, but also if the shorter path is taken but fails to
-yield an eligible next-in-service entity.
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-sched.c | 38 ++++++++++++++++++++++++++++----------
- 1 file changed, 28 insertions(+), 10 deletions(-)
-
-diff --git a/block/bfq-sched.c b/block/bfq-sched.c
-index b1a59088db88..e4a2553a2d2c 100644
---- a/block/bfq-sched.c
-+++ b/block/bfq-sched.c
-@@ -70,6 +70,7 @@ static bool bfq_update_next_in_service(struct bfq_sched_data *sd,
- 	struct bfq_entity *next_in_service = sd->next_in_service;
- 	struct bfq_queue *bfqq;
- 	bool parent_sched_may_change = false;
-+	bool change_without_lookup = false;
- 
- 	/*
- 	 * If this update is triggered by the activation, requeueing
-@@ -89,7 +90,7 @@ static bool bfq_update_next_in_service(struct bfq_sched_data *sd,
- 		 * set to true, and left as true if
- 		 * sd->next_in_service is NULL.
- 		 */
--		bool replace_next = true;
-+		change_without_lookup = true;
- 
- 		/*
- 		 * If there is already a next_in_service candidate
-@@ -102,7 +103,7 @@ static bool bfq_update_next_in_service(struct bfq_sched_data *sd,
- 			struct bfq_service_tree *st =
- 				sd->service_tree + new_entity_class_idx;
- 
--			replace_next =
-+			change_without_lookup =
- 				(new_entity_class_idx ==
- 				 bfq_class_idx(next_in_service)
- 				 &&
-@@ -112,15 +113,32 @@ static bool bfq_update_next_in_service(struct bfq_sched_data *sd,
- 					new_entity->finish));
- 		}
- 
--		if (replace_next)
-+		if (change_without_lookup) {
- 			next_in_service = new_entity;
--	} else /* invoked because of a deactivation: lookup needed */
-+			bfqq = bfq_entity_to_bfqq(next_in_service);
-+
-+			if (bfqq)
-+				bfq_log_bfqq(bfqq->bfqd, bfqq,
-+				"update_next_in_service: chose without lookup");
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+			else {
-+				struct bfq_group *bfqg =
-+					container_of(next_in_service,
-+						     struct bfq_group, entity);
-+
-+				bfq_log_bfqg((struct bfq_data*)bfqg->bfqd, bfqg,
-+				"update_next_in_service: chose without lookup");
-+			}
-+#endif
-+		}
-+	}
-+
-+	if (!change_without_lookup) /* lookup needed */
- 		next_in_service = bfq_lookup_next_entity(sd, expiration);
- 
--	if (next_in_service) {
-+	if (next_in_service)
- 		parent_sched_may_change = !sd->next_in_service ||
- 			bfq_update_parent_budget(next_in_service);
--	}
- 
- 	sd->next_in_service = next_in_service;
- 
-@@ -1053,7 +1071,7 @@ static void bfq_update_fin_time_enqueue(struct bfq_entity *entity,
- 
- 		if (bfqq) {
- 			bfq_log_bfqq(bfqq->bfqd, bfqq,
--				     "__activate_entity: new queue finish %llu",
-+				     "update_fin_time_enqueue: new queue finish %llu",
- 				     ((entity->finish>>10)*1000)>>12);
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
- 		} else {
-@@ -1061,7 +1079,7 @@ static void bfq_update_fin_time_enqueue(struct bfq_entity *entity,
- 				container_of(entity, struct bfq_group, entity);
- 
- 			bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
--				     "__activate_entity: new group finish %llu",
-+				     "update_fin_time_enqueue: new group finish %llu",
- 				     ((entity->finish>>10)*1000)>>12);
- #endif
- 		}
-@@ -1071,7 +1089,7 @@ static void bfq_update_fin_time_enqueue(struct bfq_entity *entity,
- 
- 	if (bfqq) {
- 		bfq_log_bfqq(bfqq->bfqd, bfqq,
--			"__activate_entity: queue %seligible in st %p",
-+			"update_fin_time_enqueue: queue %seligible in st %p",
- 			     entity->start <= st->vtime ? "" : "non ", st);
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	} else {
-@@ -1079,7 +1097,7 @@ static void bfq_update_fin_time_enqueue(struct bfq_entity *entity,
- 			container_of(entity, struct bfq_group, entity);
- 
- 		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
--			"__activate_entity: group %seligible in st %p",
-+			"update_fin_time_enqueue: group %seligible in st %p",
- 			     entity->start <= st->vtime ? "" : "non ", st);
- #endif
- 	}
-
-From 6565e4d1aac029b6f0a5d86a4c6ef38608838eac Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Thu, 31 Aug 2017 19:24:26 +0200
-Subject: [PATCH 40/51] doc, block, bfq: fix some typos and stale sentences
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
-Reviewed-by: Jeremy Hickman <jeremywh7@gmail.com>
-Reviewed-by: Laurentiu Nicola <lnicola@dend.ro>
----
- Documentation/block/bfq-iosched.txt | 2 +-
- 1 file changed, 1 insertion(+), 1 deletion(-)
-
-diff --git a/Documentation/block/bfq-iosched.txt b/Documentation/block/bfq-iosched.txt
-index 0e59f1c9d30e..dcfe15523da3 100644
---- a/Documentation/block/bfq-iosched.txt
-+++ b/Documentation/block/bfq-iosched.txt
-@@ -17,7 +17,7 @@ instances of BFQ are available (otherwise only the first instance):
- - bfq-mq: development version of BFQ for blk-mq; this version contains
-    also all latest features and fixes not yet landed in mainline, plus many
-    safety checks
--- bfq: BFQ for legacy blk; also this version contains latest features
-+- bfq-sq: BFQ for legacy blk; also this version contains latest features
-    and fixes, as well as safety checks
- 
- In its default configuration, BFQ privileges latency over
-
-From 261ee8cc9f43e03d790a07184f0bcaa504ee6737 Mon Sep 17 00:00:00 2001
-From: Luca Miccio <lucmiccio@gmail.com>
-Date: Wed, 13 Sep 2017 12:03:56 +0200
-Subject: [PATCH 41/51] bfq-mq, bfq-sq: Disable writeback throttling
-
-Similarly to CFQ, BFQ has its write-throttling heuristics, and it
-is better not to combine them with further write-throttling
-heuristics of a different nature.
-So this commit disables write-back throttling for a device if BFQ
-is used as I/O scheduler for that device.
-
-Signed-off-by: Luca Miccio <lucmiccio@gmail.com>
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
-Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
----
- block/bfq-mq-iosched.c | 2 ++
- block/bfq-sq-iosched.c | 7 +++++++
- 2 files changed, 9 insertions(+)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index b5c848650375..7d27d5b3befb 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -89,6 +89,7 @@
- #include "blk-mq-tag.h"
- #include "blk-mq-sched.h"
- #include "bfq-mq.h"
-+#include "blk-wbt.h"
- 
- /* Expiration time of sync (0) and async (1) requests, in ns. */
- static const u64 bfq_fifo_expire[2] = { NSEC_PER_SEC / 4, NSEC_PER_SEC / 8 };
-@@ -5260,6 +5261,7 @@ static int bfq_init_queue(struct request_queue *q, struct elevator_type *e)
- 	bfq_init_root_group(bfqd->root_group, bfqd);
- 	bfq_init_entity(&bfqd->oom_bfqq.entity, bfqd->root_group);
- 
-+	wbt_disable_default(q);
- 	return 0;
- 
- out_free:
-diff --git a/block/bfq-sq-iosched.c b/block/bfq-sq-iosched.c
-index 42393ab889a9..6fdc3b1d5bb8 100644
---- a/block/bfq-sq-iosched.c
-+++ b/block/bfq-sq-iosched.c
-@@ -83,6 +83,7 @@
- #include <linux/ioprio.h>
- #include "blk.h"
- #include "bfq.h"
-+#include "blk-wbt.h"
- 
- /* Expiration time of sync (0) and async (1) requests, in ns. */
- static const u64 bfq_fifo_expire[2] = { NSEC_PER_SEC / 4, NSEC_PER_SEC / 8 };
-@@ -4976,6 +4977,11 @@ static int bfq_init_queue(struct request_queue *q, struct elevator_type *e)
- 	return -ENOMEM;
- }
- 
-+static void bfq_registered_queue(struct request_queue *q)
-+{
-+	wbt_disable_default(q);
-+}
-+
- static void bfq_slab_kill(void)
- {
- 	kmem_cache_destroy(bfq_pool);
-@@ -5285,6 +5291,7 @@ static struct elevator_type iosched_bfq = {
- 		.elevator_may_queue_fn =	bfq_may_queue,
- 		.elevator_init_fn =		bfq_init_queue,
- 		.elevator_exit_fn =		bfq_exit_queue,
-+		.elevator_registered_fn =	bfq_registered_queue,
- 	},
- 	.icq_size =		sizeof(struct bfq_io_cq),
- 	.icq_align =		__alignof__(struct bfq_io_cq),
-
-From 40ea0aed088791da27fcfa51f3b64d1f96b0d06e Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Tue, 12 Sep 2017 16:45:53 +0200
-Subject: [PATCH 42/51] bfq-mq, bfq-sq: fix wrong init of saved start time for
- weight raising
-
-This commit fixes a bug that causes bfq to fail to guarantee a high
-responsiveness on some drives, if there is heavy random read+write I/O
-in the background. More precisely, such a failure allowed this bug to
-be found [1], but the bug may well cause other yet unreported
-anomalies.
-
-BFQ raises the weight of the bfq_queues associated with soft real-time
-applications, to privilege the I/O, and thus reduce latency, for these
-applications. This mechanism is named soft-real-time weight raising in
-BFQ. A soft real-time period may happen to be nested into an
-interactive weight raising period, i.e., it may happen that, when a
-bfq_queue switches to a soft real-time weight-raised state, the
-bfq_queue is already being weight-raised because deemed interactive
-too. In this case, BFQ saves in a special variable
-wr_start_at_switch_to_srt, the time instant when the interactive
-weight-raising period started for the bfq_queue, i.e., the time
-instant when BFQ started to deem the bfq_queue interactive. This value
-is then used to check whether the interactive weight-raising period
-would still be in progress when the soft real-time weight-raising
-period ends.  If so, interactive weight raising is restored for the
-bfq_queue. This restore is useful, in particular, because it prevents
-bfq_queues from losing their interactive weight raising prematurely,
-as a consequence of spurious, short-lived soft real-time
-weight-raising periods caused by wrong detections as soft real-time.
-
-If, instead, a bfq_queue switches to soft-real-time weight raising
-while it *is not* already in an interactive weight-raising period,
-then the variable wr_start_at_switch_to_srt has no meaning during the
-following soft real-time weight-raising period. Unfortunately the
-handling of this case is wrong in BFQ: not only the variable is not
-flagged somehow as meaningless, but it is also set to the time when
-the switch to soft real-time weight-raising occurs. This may cause an
-interactive weight-raising period to be considered mistakenly as still
-in progress, and thus a spurious interactive weight-raising period to
-start for the bfq_queue, at the end of the soft-real-time
-weight-raising period. In particular the spurious interactive
-weight-raising period will be considered as still in progress, if the
-soft-real-time weight-raising period does not last very long. The
-bfq_queue will then be wrongly privileged and, if I/O bound, will
-unjustly steal bandwidth to truly interactive or soft real-time
-bfq_queues, harming responsiveness and low latency.
-
-This commit fixes this issue by just setting wr_start_at_switch_to_srt
-to minus infinity (farthest past time instant according to jiffies
-macros): when the soft-real-time weight-raising period ends, certainly
-no interactive weight-raising period will be considered as still in
-progress.
-
-[1] Background I/O Type: Random - Background I/O mix: Reads and writes
-- Application to start: LibreOffice Writer in
-http://www.phoronix.com/scan.php?page=news_item&px=Linux-4.13-IO-Laptop
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
-Signed-off-by: Angelo Ruocco <angeloruocco90@gmail.com>
-Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
-Tested-by: Lee Tibbert <lee.tibbert@gmail.com>
-Tested-by: Mirko Montanari <mirkomontanari91@gmail.com>
----
- block/bfq-mq-iosched.c | 50 +++++++++++++++++++++++++++++++-------------------
- block/bfq-sq-iosched.c | 50 +++++++++++++++++++++++++++++++-------------------
- 2 files changed, 62 insertions(+), 38 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 7d27d5b3befb..f378519b6d33 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -1204,6 +1204,24 @@ static bool bfq_bfqq_update_budg_for_activation(struct bfq_data *bfqd,
- 	return wr_or_deserves_wr;
- }
- 
-+/*
-+ * Return the farthest future time instant according to jiffies
-+ * macros.
-+ */
-+static unsigned long bfq_greatest_from_now(void)
-+{
-+	return jiffies + MAX_JIFFY_OFFSET;
-+}
-+
-+/*
-+ * Return the farthest past time instant according to jiffies
-+ * macros.
-+ */
-+static unsigned long bfq_smallest_from_now(void)
-+{
-+	return jiffies - MAX_JIFFY_OFFSET;
-+}
-+
- static void bfq_update_bfqq_wr_on_rq_arrival(struct bfq_data *bfqd,
- 					     struct bfq_queue *bfqq,
- 					     unsigned int old_wr_coeff,
-@@ -1218,7 +1236,19 @@ static void bfq_update_bfqq_wr_on_rq_arrival(struct bfq_data *bfqd,
- 			bfqq->wr_coeff = bfqd->bfq_wr_coeff;
- 			bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
- 		} else {
--			bfqq->wr_start_at_switch_to_srt = jiffies;
-+			/*
-+			 * No interactive weight raising in progress
-+			 * here: assign minus infinity to
-+			 * wr_start_at_switch_to_srt, to make sure
-+			 * that, at the end of the soft-real-time
-+			 * weight raising periods that is starting
-+			 * now, no interactive weight-raising period
-+			 * may be wrongly considered as still in
-+			 * progress (and thus actually started by
-+			 * mistake).
-+			 */
-+			bfqq->wr_start_at_switch_to_srt =
-+				bfq_smallest_from_now();
- 			bfqq->wr_coeff = bfqd->bfq_wr_coeff *
- 				BFQ_SOFTRT_WEIGHT_FACTOR;
- 			bfqq->wr_cur_max_time =
-@@ -3174,24 +3204,6 @@ static unsigned long bfq_bfqq_softrt_next_start(struct bfq_data *bfqd,
- 		   jiffies + nsecs_to_jiffies(bfqq->bfqd->bfq_slice_idle) + 4);
- }
- 
--/*
-- * Return the farthest future time instant according to jiffies
-- * macros.
-- */
--static unsigned long bfq_greatest_from_now(void)
--{
--	return jiffies + MAX_JIFFY_OFFSET;
--}
--
--/*
-- * Return the farthest past time instant according to jiffies
-- * macros.
-- */
--static unsigned long bfq_smallest_from_now(void)
--{
--	return jiffies - MAX_JIFFY_OFFSET;
--}
--
- /**
-  * bfq_bfqq_expire - expire a queue.
-  * @bfqd: device owning the queue.
-diff --git a/block/bfq-sq-iosched.c b/block/bfq-sq-iosched.c
-index 6fdc3b1d5bb8..f4654436cd55 100644
---- a/block/bfq-sq-iosched.c
-+++ b/block/bfq-sq-iosched.c
-@@ -1165,6 +1165,24 @@ static bool bfq_bfqq_update_budg_for_activation(struct bfq_data *bfqd,
- 	return wr_or_deserves_wr;
- }
- 
-+/*
-+ * Return the farthest future time instant according to jiffies
-+ * macros.
-+ */
-+static unsigned long bfq_greatest_from_now(void)
-+{
-+	return jiffies + MAX_JIFFY_OFFSET;
-+}
-+
-+/*
-+ * Return the farthest past time instant according to jiffies
-+ * macros.
-+ */
-+static unsigned long bfq_smallest_from_now(void)
-+{
-+	return jiffies - MAX_JIFFY_OFFSET;
-+}
-+
- static void bfq_update_bfqq_wr_on_rq_arrival(struct bfq_data *bfqd,
- 					     struct bfq_queue *bfqq,
- 					     unsigned int old_wr_coeff,
-@@ -1179,7 +1197,19 @@ static void bfq_update_bfqq_wr_on_rq_arrival(struct bfq_data *bfqd,
- 			bfqq->wr_coeff = bfqd->bfq_wr_coeff;
- 			bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
- 		} else {
--			bfqq->wr_start_at_switch_to_srt = jiffies;
-+			/*
-+			 * No interactive weight raising in progress
-+			 * here: assign minus infinity to
-+			 * wr_start_at_switch_to_srt, to make sure
-+			 * that, at the end of the soft-real-time
-+			 * weight raising periods that is starting
-+			 * now, no interactive weight-raising period
-+			 * may be wrongly considered as still in
-+			 * progress (and thus actually started by
-+			 * mistake).
-+			 */
-+			bfqq->wr_start_at_switch_to_srt =
-+				bfq_smallest_from_now();
- 			bfqq->wr_coeff = bfqd->bfq_wr_coeff *
- 				BFQ_SOFTRT_WEIGHT_FACTOR;
- 			bfqq->wr_cur_max_time =
-@@ -3067,24 +3097,6 @@ static unsigned long bfq_bfqq_softrt_next_start(struct bfq_data *bfqd,
- 		   jiffies + nsecs_to_jiffies(bfqq->bfqd->bfq_slice_idle) + 4);
- }
- 
--/*
-- * Return the farthest future time instant according to jiffies
-- * macros.
-- */
--static unsigned long bfq_greatest_from_now(void)
--{
--	return jiffies + MAX_JIFFY_OFFSET;
--}
--
--/*
-- * Return the farthest past time instant according to jiffies
-- * macros.
-- */
--static unsigned long bfq_smallest_from_now(void)
--{
--	return jiffies - MAX_JIFFY_OFFSET;
--}
--
- /**
-  * bfq_bfqq_expire - expire a queue.
-  * @bfqd: device owning the queue.
-
-From 9dbea44b6f721baeff35b9fdf628ec55fe00e09d Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Thu, 14 Sep 2017 05:12:58 -0400
-Subject: [PATCH 43/51] Fix commit "Unnest request-queue and ioc locks from
- scheduler locks"
-
-The commit "Unnest request-queue and ioc locks from scheduler locks"
-mistakenly removed the setting of the split flag in function
-bfq_prepare_request. This commit puts this missing instruction back in
-its place.
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-mq-iosched.c | 12 ++++++++++++
- 1 file changed, 12 insertions(+)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index f378519b6d33..288078e68a2a 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -744,6 +744,12 @@ bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_data *bfqd,
- 	bfqq->wr_cur_max_time = bic->saved_wr_cur_max_time;
- 	BUG_ON(time_is_after_jiffies(bfqq->last_wr_start_finish));
- 
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		     "[%s] bic %p wr_coeff %d start_finish %lu max_time %lu",
-+		     __func__,
-+		     bic, bfqq->wr_coeff, bfqq->last_wr_start_finish,
-+		     bfqq->wr_cur_max_time);
-+
- 	if (bfqq->wr_coeff > 1 && (bfq_bfqq_in_large_burst(bfqq) ||
- 				   time_is_before_jiffies(bfqq->last_wr_start_finish +
- 							  bfqq->wr_cur_max_time))) {
-@@ -2208,6 +2214,11 @@ static void bfq_bfqq_save_state(struct bfq_queue *bfqq)
- 	bic->saved_last_wr_start_finish = bfqq->last_wr_start_finish;
- 	bic->saved_wr_cur_max_time = bfqq->wr_cur_max_time;
- 	BUG_ON(time_is_after_jiffies(bfqq->last_wr_start_finish));
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		     "[%s] bic %p wr_coeff %d start_finish %lu max_time %lu",
-+		     __func__,
-+		     bic, bfqq->wr_coeff, bfqq->last_wr_start_finish,
-+		     bfqq->wr_cur_max_time);
- }
- 
- static void
-@@ -4950,6 +4961,7 @@ static void bfq_prepare_request(struct request *rq, struct bio *bio)
- 				bic->saved_in_large_burst = true;
- 
- 			bfqq = bfq_split_bfqq(bic, bfqq);
-+			split = true;
- 
- 			if (!bfqq)
- 				bfqq = bfq_get_bfqq_handle_split(bfqd, bic, bio,
-
-From d4ebb2a66a23dc183792088c521f2be2193b56db Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Fri, 15 Sep 2017 01:53:51 -0400
-Subject: [PATCH 44/51] bfq-sq, bfq-mq: check and switch back to interactive wr
- also on queue split
-
-As already explained in the message of commit "bfq-mq, bfq-sq: fix
-wrong init of saved start time for weight raising", if a soft
-real-time weight-raising period happens to be nested in a larger
-interactive weight-raising period, then BFQ restores the interactive
-weight raising at the end of the soft real-time weight raising. In
-particular, BFQ checks whether the latter has ended only on request
-dispatches.
-
-Unfortunately, the above scheme fails to restore interactive weight
-raising in the following corner case: if a bfq_queue, say Q,
-1) Is merged with another bfq_queue while it is in a nested soft
-real-time weight-raising period. The weight-raising state of Q is
-then saved, and not considered any longer until a split occurs.
-2) Is split from the other bfq_queue(s) at a time instant when its
-soft real-time weight raising is already finished.
-On the split, while resuming the previous, soft real-time
-weight-raised state of the bfq_queue Q, BFQ checks whether the
-current soft real-time weight-raising period is actually over. If so,
-BFQ switches weight raising off for Q, *without* checking whether the
-soft real-time period was actually nested in a non-yet-finished
-interactive weight-raising period.
-
-This commit addresses this issue by adding the above missing check in
-bfq_queue splits, and restoring interactive weight raising if needed.
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
-Tested-by: Angelo Ruocco <angeloruocco90@gmail.com>
-Tested-by: Mirko Montanari <mirkomontanari91@gmail.com>
----
- block/bfq-mq-iosched.c | 29 +++++++++++++++++++++--------
- block/bfq-sq-iosched.c | 35 +++++++++++++++++++++++++++--------
- 2 files changed, 48 insertions(+), 16 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 288078e68a2a..6130a95c6497 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -716,6 +716,15 @@ static unsigned int bfq_wr_duration(struct bfq_data *bfqd)
- 	return dur;
- }
- 
-+/* switch back from soft real-time to interactive weight raising */
-+static void switch_back_to_interactive_wr(struct bfq_queue *bfqq,
-+					  struct bfq_data *bfqd)
-+{
-+	bfqq->wr_coeff = bfqd->bfq_wr_coeff;
-+	bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
-+	bfqq->last_wr_start_finish = bfqq->wr_start_at_switch_to_srt;
-+}
-+
- static void
- bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_data *bfqd,
- 		      struct bfq_io_cq *bic, bool bfq_already_existing)
-@@ -753,12 +762,20 @@ bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_data *bfqd,
- 	if (bfqq->wr_coeff > 1 && (bfq_bfqq_in_large_burst(bfqq) ||
- 				   time_is_before_jiffies(bfqq->last_wr_start_finish +
- 							  bfqq->wr_cur_max_time))) {
--		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		if (bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time &&
-+		    !bfq_bfqq_in_large_burst(bfqq) &&
-+		    time_is_after_eq_jiffies(bfqq->wr_start_at_switch_to_srt +
-+					     bfq_wr_duration(bfqd))) {
-+			switch_back_to_interactive_wr(bfqq, bfqd);
-+			bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			     "resume state: switching back to interactive");
-+		} else {
-+			bfqq->wr_coeff = 1;
-+			bfq_log_bfqq(bfqq->bfqd, bfqq,
- 			     "resume state: switching off wr (%lu + %lu < %lu)",
- 			     bfqq->last_wr_start_finish, bfqq->wr_cur_max_time,
- 			     jiffies);
--
--		bfqq->wr_coeff = 1;
-+		}
- 	}
- 
- 	/* make sure weight will be updated, however we got here */
-@@ -3820,11 +3837,7 @@ static void bfq_update_wr_data(struct bfq_data *bfqd, struct bfq_queue *bfqq)
- 					bfq_wr_duration(bfqd)))
- 				bfq_bfqq_end_wr(bfqq);
- 			else {
--				/* switch back to interactive wr */
--				bfqq->wr_coeff = bfqd->bfq_wr_coeff;
--				bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
--				bfqq->last_wr_start_finish =
--					bfqq->wr_start_at_switch_to_srt;
-+				switch_back_to_interactive_wr(bfqq, bfqd);
- 				BUG_ON(time_is_after_jiffies(
- 					       bfqq->last_wr_start_finish));
- 				bfqq->entity.prio_changed = 1;
-diff --git a/block/bfq-sq-iosched.c b/block/bfq-sq-iosched.c
-index f4654436cd55..e07d5d1c0d40 100644
---- a/block/bfq-sq-iosched.c
-+++ b/block/bfq-sq-iosched.c
-@@ -678,6 +678,15 @@ static unsigned int bfq_wr_duration(struct bfq_data *bfqd)
- 	return dur;
- }
- 
-+/* switch back from soft real-time to interactive weight raising */
-+static void switch_back_to_interactive_wr(struct bfq_queue *bfqq,
-+					  struct bfq_data *bfqd)
-+{
-+	bfqq->wr_coeff = bfqd->bfq_wr_coeff;
-+	bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
-+	bfqq->last_wr_start_finish = bfqq->wr_start_at_switch_to_srt;
-+}
-+
- static void
- bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_data *bfqd,
- 		      struct bfq_io_cq *bic, bool bfq_already_existing)
-@@ -705,15 +714,29 @@ bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_data *bfqd,
- 	bfqq->wr_cur_max_time = bic->saved_wr_cur_max_time;
- 	BUG_ON(time_is_after_jiffies(bfqq->last_wr_start_finish));
- 
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		     "[%s] bic %p wr_coeff %d start_finish %lu max_time %lu",
-+		     __func__,
-+		     bic, bfqq->wr_coeff, bfqq->last_wr_start_finish,
-+		     bfqq->wr_cur_max_time);
-+
- 	if (bfqq->wr_coeff > 1 && (bfq_bfqq_in_large_burst(bfqq) ||
- 				   time_is_before_jiffies(bfqq->last_wr_start_finish +
- 							  bfqq->wr_cur_max_time))) {
--		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		if (bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time &&
-+		    !bfq_bfqq_in_large_burst(bfqq) &&
-+		    time_is_after_eq_jiffies(bfqq->wr_start_at_switch_to_srt +
-+					     bfq_wr_duration(bfqd))) {
-+			switch_back_to_interactive_wr(bfqq, bfqd);
-+			bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			     "resume state: switching back to interactive");
-+		} else {
-+			bfqq->wr_coeff = 1;
-+			bfq_log_bfqq(bfqq->bfqd, bfqq,
- 			     "resume state: switching off wr (%lu + %lu < %lu)",
- 			     bfqq->last_wr_start_finish, bfqq->wr_cur_max_time,
- 			     jiffies);
--
--		bfqq->wr_coeff = 1;
-+		}
- 	}
- 
- 	/* make sure weight will be updated, however we got here */
-@@ -3703,11 +3726,7 @@ static void bfq_update_wr_data(struct bfq_data *bfqd, struct bfq_queue *bfqq)
- 					bfq_wr_duration(bfqd)))
- 				bfq_bfqq_end_wr(bfqq);
- 			else {
--				/* switch back to interactive wr */
--				bfqq->wr_coeff = bfqd->bfq_wr_coeff;
--				bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
--				bfqq->last_wr_start_finish =
--					bfqq->wr_start_at_switch_to_srt;
-+				switch_back_to_interactive_wr(bfqq, bfqd);
- 				BUG_ON(time_is_after_jiffies(
- 					       bfqq->last_wr_start_finish));
- 				bfqq->entity.prio_changed = 1;
-
-From 9eaec0c3a2d675763b09da81c9117a9c43bce942 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Fri, 15 Sep 2017 04:58:33 -0400
-Subject: [PATCH 45/51] bfq-sq, bfq-mq: let early-merged queues be
- weight-raised on split too
-
-A just-created bfq_queue, say Q, may happen to be merged with another
-bfq_queue on the very first invocation of the function
-__bfq_insert_request. In such a case, even if Q would clearly deserve
-interactive weight raising (as it has just been created), the function
-bfq_add_request does not make it to be invoked for Q, and thus to
-activate weight raising for Q. As a consequence, when the state of Q
-is saved for a possible future restore, after a split of Q from the
-other bfq_queue(s), such a state happens to be (unjustly)
-non-weight-raised. Then the bfq_queue will not enjoy any weight
-raising on the split, even if should still be in an interactive
-weight-raising period when the split occurs.
-
-This commit solves this problem as follows, for a just-created
-bfq_queue that is being early-merged: it stores directly, in the saved
-state of the bfq_queue, the weight-raising state that would have been
-assigned to the bfq_queue if not early-merged.
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
-Tested-by: Angelo Ruocco <angeloruocco90@gmail.com>
-Tested-by: Mirko Montanari <mirkomontanari91@gmail.com>
----
- block/bfq-mq-iosched.c | 28 +++++++++++++++++++++++-----
- block/bfq-sq-iosched.c | 28 +++++++++++++++++++++++-----
- 2 files changed, 46 insertions(+), 10 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 6130a95c6497..af84e506e897 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -2226,10 +2226,27 @@ static void bfq_bfqq_save_state(struct bfq_queue *bfqq)
- 	bic->saved_IO_bound = bfq_bfqq_IO_bound(bfqq);
- 	bic->saved_in_large_burst = bfq_bfqq_in_large_burst(bfqq);
- 	bic->was_in_burst_list = !hlist_unhashed(&bfqq->burst_list_node);
--	bic->saved_wr_coeff = bfqq->wr_coeff;
--	bic->saved_wr_start_at_switch_to_srt = bfqq->wr_start_at_switch_to_srt;
--	bic->saved_last_wr_start_finish = bfqq->last_wr_start_finish;
--	bic->saved_wr_cur_max_time = bfqq->wr_cur_max_time;
-+	if (unlikely(bfq_bfqq_just_created(bfqq) &&
-+		     !bfq_bfqq_in_large_burst(bfqq))) {
-+		/*
-+		 * bfqq being merged ritgh after being created: bfqq
-+		 * would have deserved interactive weight raising, but
-+		 * did not make it to be set in a weight-raised state,
-+		 * because of this early merge.  Store directly the
-+		 * weight-raising state that would have been assigned
-+		 * to bfqq, so that to avoid that bfqq unjustly fails
-+		 * to enjoy weight raising if split soon.
-+		 */
-+		bic->saved_wr_coeff = bfqq->bfqd->bfq_wr_coeff;
-+		bic->saved_wr_cur_max_time = bfq_wr_duration(bfqq->bfqd);
-+		bic->saved_last_wr_start_finish = jiffies;
-+	} else {
-+		bic->saved_wr_coeff = bfqq->wr_coeff;
-+		bic->saved_wr_start_at_switch_to_srt =
-+			bfqq->wr_start_at_switch_to_srt;
-+		bic->saved_last_wr_start_finish = bfqq->last_wr_start_finish;
-+		bic->saved_wr_cur_max_time = bfqq->wr_cur_max_time;
-+	}
- 	BUG_ON(time_is_after_jiffies(bfqq->last_wr_start_finish));
- 	bfq_log_bfqq(bfqq->bfqd, bfqq,
- 		     "[%s] bic %p wr_coeff %d start_finish %lu max_time %lu",
-@@ -4560,7 +4577,6 @@ static void __bfq_insert_request(struct bfq_data *bfqd, struct request *rq)
- 				     bfqq->allocated);
- 
- 			new_bfqq->ref++;
--			bfq_clear_bfqq_just_created(bfqq);
- 			/*
- 			 * If the bic associated with the process
- 			 * issuing this request still points to bfqq
-@@ -4572,6 +4588,8 @@ static void __bfq_insert_request(struct bfq_data *bfqd, struct request *rq)
- 			if (bic_to_bfqq(RQ_BIC(rq), 1) == bfqq)
- 				bfq_merge_bfqqs(bfqd, RQ_BIC(rq),
- 						bfqq, new_bfqq);
-+
-+			bfq_clear_bfqq_just_created(bfqq);
- 			/*
- 			 * rq is about to be enqueued into new_bfqq,
- 			 * release rq reference on bfqq
-diff --git a/block/bfq-sq-iosched.c b/block/bfq-sq-iosched.c
-index e07d5d1c0d40..0c48f527fe3f 100644
---- a/block/bfq-sq-iosched.c
-+++ b/block/bfq-sq-iosched.c
-@@ -2105,10 +2105,27 @@ static void bfq_bfqq_save_state(struct bfq_queue *bfqq)
- 	bic->saved_IO_bound = bfq_bfqq_IO_bound(bfqq);
- 	bic->saved_in_large_burst = bfq_bfqq_in_large_burst(bfqq);
- 	bic->was_in_burst_list = !hlist_unhashed(&bfqq->burst_list_node);
--	bic->saved_wr_coeff = bfqq->wr_coeff;
--	bic->saved_wr_start_at_switch_to_srt = bfqq->wr_start_at_switch_to_srt;
--	bic->saved_last_wr_start_finish = bfqq->last_wr_start_finish;
--	bic->saved_wr_cur_max_time = bfqq->wr_cur_max_time;
-+	if (unlikely(bfq_bfqq_just_created(bfqq) &&
-+		     !bfq_bfqq_in_large_burst(bfqq))) {
-+		/*
-+		 * bfqq being merged ritgh after being created: bfqq
-+		 * would have deserved interactive weight raising, but
-+		 * did not make it to be set in a weight-raised state,
-+		 * because of this early merge.	Store directly the
-+		 * weight-raising state that would have been assigned
-+		 * to bfqq, so that to avoid that bfqq unjustly fails
-+		 * to enjoy weight raising if split soon.
-+		 */
-+		bic->saved_wr_coeff = bfqq->bfqd->bfq_wr_coeff;
-+		bic->saved_wr_cur_max_time = bfq_wr_duration(bfqq->bfqd);
-+		bic->saved_last_wr_start_finish = jiffies;
-+	} else {
-+		bic->saved_wr_coeff = bfqq->wr_coeff;
-+		bic->saved_wr_start_at_switch_to_srt =
-+			bfqq->wr_start_at_switch_to_srt;
-+		bic->saved_last_wr_start_finish = bfqq->last_wr_start_finish;
-+		bic->saved_wr_cur_max_time = bfqq->wr_cur_max_time;
-+	}
- 	BUG_ON(time_is_after_jiffies(bfqq->last_wr_start_finish));
- }
- 
-@@ -4383,10 +4400,11 @@ static void bfq_insert_request(struct request_queue *q, struct request *rq)
- 			new_bfqq->allocated[rq_data_dir(rq)]++;
- 			bfqq->allocated[rq_data_dir(rq)]--;
- 			new_bfqq->ref++;
--			bfq_clear_bfqq_just_created(bfqq);
- 			if (bic_to_bfqq(RQ_BIC(rq), 1) == bfqq)
- 				bfq_merge_bfqqs(bfqd, RQ_BIC(rq),
- 						bfqq, new_bfqq);
-+
-+			bfq_clear_bfqq_just_created(bfqq);
- 			/*
- 			 * rq is about to be enqueued into new_bfqq,
- 			 * release rq reference on bfqq
-
-From cb05150675095cb97ab22e4955eb82e4fe2e9dbe Mon Sep 17 00:00:00 2001
-From: omcira <omcira@gmail.com>
-Date: Mon, 18 Sep 2017 10:49:48 +0200
-Subject: [PATCH 46/51] bfq-sq, bfq-mq: decrease burst size when queues in
- burst exit
-
-If many queues belonging to the same group happen to be created
-shortly after each other, then the concurrent processes associated
-with these queues have typically a common goal, and they get it done
-as soon as possible if not hampered by device idling.  Examples are
-processes spawned by git grep, or by systemd during boot. As for
-device idling, this mechanism is currently necessary for weight
-raising to succeed in its goal: privileging I/O.  In view of these
-facts, BFQ does not provide the above queues with either weight
-raising or device idling.
-
-On the other hand, a burst of queue creations may be caused also by
-the start-up of a complex application. In this case, these queues need
-usually to be served one after the other, and as quickly as possible,
-to maximise responsiveness. Therefore, in this case the best strategy
-is to weight-raise all the queues created during the burst, i.e., the
-exact opposite of the strategy for the above case.
-
-To distinguish between the two cases, BFQ uses an empirical burst-size
-threshold, found through extensive tests and monitoring of daily
-usage. Only large bursts, i.e., burst with a size above this
-threshold, are considered as generated by a high number of parallel
-processes. In this respect, upstart-based boot proved to be rather
-hard to detect as generating a large burst of queue creations, because
-with upstart most of the queues created in a burst exit *before* the
-next queues in the same burst are created. To address this issue, I
-changed the burst-detection mechanism so as to not decrease the size
-of the current burst even if one of the queues in the burst is
-eliminated.
-
-Unfortunately, this missing decrease causes false positives on very
-fast systems: on the start-up of a complex application, such as
-libreoffice writer, so many queues are created, served and exited
-shortly after each other, that a large burst of queue creations is
-wrongly detected as occurring. These false positives just disappear if
-the size of a burst is decreased when one of the queues in the burst
-exits. This commit restores the missing burst-size decrease, relying
-of the fact that upstart is apparently unlikely to be used on systems
-running this and future versions of the kernel.
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
-Signed-off-by: Mauro Andreolini <mauro.andreolini@unimore.it>
-Signed-off-by: Angelo Ruocco <angeloruocco90@gmail.com>
-Tested-by: Mirko Montanari <mirkomontanari91@gmail.com>
----
- block/bfq-mq-iosched.c | 12 +++---------
- block/bfq-sq-iosched.c | 12 +++---------
- 2 files changed, 6 insertions(+), 18 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index af84e506e897..6e413d7236ce 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -4111,16 +4111,10 @@ static void bfq_put_queue(struct bfq_queue *bfqq)
- 	BUG_ON(bfqq->entity.tree);
- 	BUG_ON(bfq_bfqq_busy(bfqq));
- 
--	if (bfq_bfqq_sync(bfqq))
--		/*
--		 * The fact that this queue is being destroyed does not
--		 * invalidate the fact that this queue may have been
--		 * activated during the current burst. As a consequence,
--		 * although the queue does not exist anymore, and hence
--		 * needs to be removed from the burst list if there,
--		 * the burst size has not to be decremented.
--		 */
-+	if (bfq_bfqq_sync(bfqq) && !hlist_unhashed(&bfqq->burst_list_node)) {
- 		hlist_del_init(&bfqq->burst_list_node);
-+		bfqq->bfqd->burst_size--;
-+	}
- 
- 	if (bfqq->bfqd)
- 		bfq_log_bfqq(bfqq->bfqd, bfqq, "put_queue: %p freed", bfqq);
-diff --git a/block/bfq-sq-iosched.c b/block/bfq-sq-iosched.c
-index 0c48f527fe3f..93034dd7b801 100644
---- a/block/bfq-sq-iosched.c
-+++ b/block/bfq-sq-iosched.c
-@@ -3945,16 +3945,10 @@ static void bfq_put_queue(struct bfq_queue *bfqq)
- 	BUG_ON(bfqq->entity.tree);
- 	BUG_ON(bfq_bfqq_busy(bfqq));
- 
--	if (bfq_bfqq_sync(bfqq))
--		/*
--		 * The fact that this queue is being destroyed does not
--		 * invalidate the fact that this queue may have been
--		 * activated during the current burst. As a consequence,
--		 * although the queue does not exist anymore, and hence
--		 * needs to be removed from the burst list if there,
--		 * the burst size has not to be decremented.
--		 */
-+	if (bfq_bfqq_sync(bfqq) && !hlist_unhashed(&bfqq->burst_list_node)) {
- 		hlist_del_init(&bfqq->burst_list_node);
-+		bfqq->bfqd->burst_size--;
-+	}
- 
- 	bfq_log_bfqq(bfqq->bfqd, bfqq, "put_queue: %p freed", bfqq);
- 
-
-From 60de7307d5e3ed7f272f12c900f631bdfe114db2 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Fri, 6 Oct 2017 19:35:38 +0200
-Subject: [PATCH 47/51] bfq-sq, bfq-mq: fix unbalanced decrements of burst size
-MIME-Version: 1.0
-Content-Type: text/plain; charset=UTF-8
-Content-Transfer-Encoding: 8bit
-
-The commit "bfq-sq, bfq-mq: decrease burst size when queues in burst
-exit" introduced the decrement of burst_size on the removal of a
-bfq_queue from the burst list. Unfortunately, this decrement can
-happen to be performed even when burst size is already equal to 0,
-because of unbalanced decrements. A description follows of the cause
-of these unbalanced decrements, namely a wrong assumption, and of the
-way how this wrong assumption leads to unbalanced decrements.
-
-The wrong assumption is that a bfq_queue can exit only if the process
-associated with the bfq_queue has exited. This is false, because a
-bfq_queue, say Q, may exit also as a consequence of a merge with
-another bfq_queue. In this case, Q exits because the I/O of its
-associated process has been redirected to another bfq_queue.
-
-The decrement unbalance occurs because Q may then be re-created after
-a split, and added back to the current burst list, *without*
-incrementing burst_size. burst_size is not incremented because Q is
-not a new bfq_queue added to the burst list, but a bfq_queue only
-temporarily removed from the list, and, before the commit "bfq-sq,
-bfq-mq: decrease burst size when queues in burst exit", burst_size was
-not decremented when Q was removed.
-
-This commit addresses this issue by just checking whether the exiting
-bfq_queue is a merged bfq_queue, and, in that case, not decrementing
-burst_size. Unfortunately, this still leaves room for unbalanced
-decrements, in the following rarer case: on a split, the bfq_queue
-happens to be inserted into a different burst list than that it was
-removed from when merged. If this happens, the number of elements in
-the new burst list becomes higher than burst_size (by one). When the
-bfq_queue then exits, it is of course not in a merged state any
-longer, thus burst_size is decremented, which results in an unbalanced
-decrement.  To handle this sporadic, unlucky case in a simple way,
-this commit also checks that burst_size is larger than 0 before
-decrementing it.
-
-Finally, this commit removes an useless, extra check: the check that
-the bfq_queue is sync, performed before checking whether the bfq_queue
-is in the burst list. This extra check is redundant, because only sync
-bfq_queues can be inserted into the burst list.
-
-Reported-by: Philip Müller <philm@manjaro.org>
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
-Signed-off-by: Angelo Ruocco <angeloruocco90@gmail.com>
-Tested-by: Philip Müller <philm@manjaro.org>
-Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
-Tested-by: Lee Tibbert <lee.tibbert@gmail.com>
----
- block/bfq-mq-iosched.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++++--
- block/bfq-sq-iosched.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++++--
- 2 files changed, 114 insertions(+), 4 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 6e413d7236ce..816bac6cdd3d 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -4111,9 +4111,36 @@ static void bfq_put_queue(struct bfq_queue *bfqq)
- 	BUG_ON(bfqq->entity.tree);
- 	BUG_ON(bfq_bfqq_busy(bfqq));
- 
--	if (bfq_bfqq_sync(bfqq) && !hlist_unhashed(&bfqq->burst_list_node)) {
-+	if (!hlist_unhashed(&bfqq->burst_list_node)) {
- 		hlist_del_init(&bfqq->burst_list_node);
--		bfqq->bfqd->burst_size--;
-+		/*
-+		 * Decrement also burst size after the removal, if the
-+		 * process associated with bfqq is exiting, and thus
-+		 * does not contribute to the burst any longer. This
-+		 * decrement helps filter out false positives of large
-+		 * bursts, when some short-lived process (often due to
-+		 * the execution of commands by some service) happens
-+		 * to start and exit while a complex application is
-+		 * starting, and thus spawning several processes that
-+		 * do I/O (and that *must not* be treated as a large
-+		 * burst, see comments on bfq_handle_burst).
-+		 *
-+		 * In particular, the decrement is performed only if:
-+		 * 1) bfqq is not a merged queue, because, if it is,
-+		 * then this free of bfqq is not triggered by the exit
-+		 * of the process bfqq is associated with, but exactly
-+		 * by the fact that bfqq has just been merged.
-+		 * 2) burst_size is greater than 0, to handle
-+		 * unbalanced decrements. Unbalanced decrements may
-+		 * happen in te following case: bfqq is inserted into
-+		 * the current burst list--without incrementing
-+		 * bust_size--because of a split, but the current
-+		 * burst list is not the burst list bfqq belonged to
-+		 * (see comments on the case of a split in
-+		 * bfq_set_request).
-+		 */
-+		if (bfqq->bic && bfqq->bfqd->burst_size > 0)
-+			bfqq->bfqd->burst_size--;
- 	}
- 
- 	if (bfqq->bfqd)
-@@ -4940,6 +4967,34 @@ static struct bfq_queue *bfq_get_bfqq_handle_split(struct bfq_data *bfqd,
- 				     "large burst");
- 			bfq_clear_bfqq_in_large_burst(bfqq);
- 			if (bic->was_in_burst_list)
-+				/*
-+				 * If bfqq was in the current
-+				 * burst list before being
-+				 * merged, then we have to add
-+				 * it back. And we do not need
-+				 * to increase burst_size, as
-+				 * we did not decrement
-+				 * burst_size when we removed
-+				 * bfqq from the burst list as
-+				 * a consequence of a merge
-+				 * (see comments in
-+				 * bfq_put_queue). In this
-+				 * respect, it would be rather
-+				 * costly to know whether the
-+				 * current burst list is still
-+				 * the same burst list from
-+				 * which bfqq was removed on
-+				 * the merge. To avoid this
-+				 * cost, if bfqq was in a
-+				 * burst list, then we add
-+				 * bfqq to the current burst
-+				 * list without any further
-+				 * check. This can cause
-+				 * inappropriate insertions,
-+				 * but rarely enough to not
-+				 * harm the detection of large
-+				 * bursts significantly.
-+				 */
- 				hlist_add_head(&bfqq->burst_list_node,
- 					       &bfqd->burst_list);
- 		}
-diff --git a/block/bfq-sq-iosched.c b/block/bfq-sq-iosched.c
-index 93034dd7b801..4bbd7f4c0154 100644
---- a/block/bfq-sq-iosched.c
-+++ b/block/bfq-sq-iosched.c
-@@ -3945,9 +3945,36 @@ static void bfq_put_queue(struct bfq_queue *bfqq)
- 	BUG_ON(bfqq->entity.tree);
- 	BUG_ON(bfq_bfqq_busy(bfqq));
- 
--	if (bfq_bfqq_sync(bfqq) && !hlist_unhashed(&bfqq->burst_list_node)) {
-+	if (!hlist_unhashed(&bfqq->burst_list_node)) {
- 		hlist_del_init(&bfqq->burst_list_node);
--		bfqq->bfqd->burst_size--;
-+		/*
-+		 * Decrement also burst size after the removal, if the
-+		 * process associated with bfqq is exiting, and thus
-+		 * does not contribute to the burst any longer. This
-+		 * decrement helps filter out false positives of large
-+		 * bursts, when some short-lived process (often due to
-+		 * the execution of commands by some service) happens
-+		 * to start and exit while a complex application is
-+		 * starting, and thus spawning several processes that
-+		 * do I/O (and that *must not* be treated as a large
-+		 * burst, see comments on bfq_handle_burst).
-+		 *
-+		 * In particular, the decrement is performed only if:
-+		 * 1) bfqq is not a merged queue, because, if it is,
-+		 * then this free of bfqq is not triggered by the exit
-+		 * of the process bfqq is associated with, but exactly
-+		 * by the fact that bfqq has just been merged.
-+		 * 2) burst_size is greater than 0, to handle
-+		 * unbalanced decrements. Unbalanced decrements may
-+		 * happen in te following case: bfqq is inserted into
-+		 * the current burst list--without incrementing
-+		 * bust_size--because of a split, but the current
-+		 * burst list is not the burst list bfqq belonged to
-+		 * (see comments on the case of a split in
-+		 * bfq_set_request).
-+		 */
-+		if (bfqq->bic && bfqq->bfqd->burst_size > 0)
-+			bfqq->bfqd->burst_size--;
- 	}
- 
- 	bfq_log_bfqq(bfqq->bfqd, bfqq, "put_queue: %p freed", bfqq);
-@@ -4691,6 +4718,34 @@ static int bfq_set_request(struct request_queue *q, struct request *rq,
- 					     "large burst");
- 				bfq_clear_bfqq_in_large_burst(bfqq);
- 				if (bic->was_in_burst_list)
-+					/*
-+					 * If bfqq was in the current
-+					 * burst list before being
-+					 * merged, then we have to add
-+					 * it back. And we do not need
-+					 * to increase burst_size, as
-+					 * we did not decrement
-+					 * burst_size when we removed
-+					 * bfqq from the burst list as
-+					 * a consequence of a merge
-+					 * (see comments in
-+					 * bfq_put_queue). In this
-+					 * respect, it would be rather
-+					 * costly to know whether the
-+					 * current burst list is still
-+					 * the same burst list from
-+					 * which bfqq was removed on
-+					 * the merge. To avoid this
-+					 * cost, if bfqq was in a
-+					 * burst list, then we add
-+					 * bfqq to the current burst
-+					 * list without any further
-+					 * check. This can cause
-+					 * inappropriate insertions,
-+					 * but rarely enough to not
-+					 * harm the detection of large
-+					 * bursts significantly.
-+					 */
- 					hlist_add_head(&bfqq->burst_list_node,
- 						       &bfqd->burst_list);
- 			}
-
-From 09adbd0f46f4ba395964b35bf611b7cc3dd84b4d Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Mon, 30 Oct 2017 16:50:50 +0100
-Subject: [PATCH 48/51] doc, block, bfq-mq: update max IOPS sustainable with
- BFQ
-
-We have investigated more deeply the performance of BFQ, in terms of
-number of IOPS that can be processed by the CPU when BFQ is used as
-I/O scheduler. In more detail, using the script [1], we have measured
-the number of IOPS reached on top of a null block device configured
-with zero latency, as a function of the workload (sequential read,
-sequential write, random read, random write) and of the system (we
-considered desktops, laptops and embedded systems).
-
-Basing on the resulting figures, with this commit we update the
-current, conservative IOPS range reported in BFQ documentation. In
-particular, the documentation now reports, for each of three different
-systems, the lowest number of IOPS obtained for that system with the
-above test (namely, the value obtained with the workload leading to
-the lowest IOPS).
-
-[1] https://github.com/Algodev-github/IOSpeed
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
-Signed-off-by: Luca Miccio <lucmiccio@gmail.com>
----
- Documentation/block/bfq-iosched.txt | 19 +++++++++++++------
- 1 file changed, 13 insertions(+), 6 deletions(-)
-
-diff --git a/Documentation/block/bfq-iosched.txt b/Documentation/block/bfq-iosched.txt
-index dcfe15523da3..595ff7a5ff34 100644
---- a/Documentation/block/bfq-iosched.txt
-+++ b/Documentation/block/bfq-iosched.txt
-@@ -29,12 +29,19 @@ for that device, by setting low_latency to 0. See Section 3 for
- details on how to configure BFQ for the desired tradeoff between
- latency and throughput, or on how to maximize throughput.
- 
--On average CPUs, the current version of BFQ can handle devices
--performing at most ~30K IOPS; at most ~50 KIOPS on faster CPUs. As a
--reference, 30-50 KIOPS correspond to very high bandwidths with
--sequential I/O (e.g., 8-12 GB/s if I/O requests are 256 KB large), and
--to 120-200 MB/s with 4KB random I/O. BFQ is currently being tested on
--multi-queue devices too.
-+BFQ has a non-null overhead, which limits the maximum IOPS that the
-+CPU can process for a device scheduled with BFQ. To give an idea of
-+the limits on slow or average CPUs, here are BFQ limits for three
-+different CPUs, on, respectively, an average laptop, an old desktop,
-+and a cheap embedded system, in case full hierarchical support is
-+enabled (i.e., CONFIG_BFQ_SQ_GROUP_IOSCHED is set for bfq-sq, or
-+CONFIG_MQ_BFQ_GROUP_IOSCHED is set for bfq-mq, or, finally,
-+CONFIG_BFQ_GROUP_IOSCHED is set for bfq):
-+- Intel i7-4850HQ: 250 KIOPS
-+- AMD A8-3850: 170 KIOPS
-+- ARM CortexTM-A53 Octa-core: 45 KIOPS
-+
-+BFQ works for multi-queue devices too (bfq and bfq-mq instances).
- 
- The table of contents follows. Impatients can just jump to Section 3.
- 
-
-From be94f97b577dc587593185224a7718aa59ac43f7 Mon Sep 17 00:00:00 2001
-From: Luca Miccio <lucmiccio@gmail.com>
-Date: Tue, 31 Oct 2017 09:50:11 +0100
-Subject: [PATCH 49/51] block, bfq-mq: add missing invocations of
- bfqg_stats_update_io_add/remove
-
-bfqg_stats_update_io_add and bfqg_stats_update_io_remove are to be
-invoked, respectively, when an I/O request enters and when an I/O
-request exits the scheduler. Unfortunately, bfq-mq does not fully comply
-with this scheme, because it does not invoke these functions for
-requests that are inserted into or extracted from its priority
-dispatch list. This commit fixes this mistake.
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
-Signed-off-by: Luca Miccio <lucmiccio@gmail.com>
----
- block/bfq-mq-iosched.c | 24 +++++++++++++++++++-----
- 1 file changed, 19 insertions(+), 5 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 816bac6cdd3d..fbf28804c220 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -1394,7 +1394,6 @@ static void bfq_bfqq_handle_idle_busy_switch(struct bfq_data *bfqd,
- 	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
- 
- 	BUG_ON(bfqq == bfqd->in_service_queue);
--	bfqg_stats_update_io_add(bfqq_group(RQ_BFQQ(rq)), bfqq, rq->cmd_flags);
- 
- 	/*
- 	 * bfqq deserves to be weight-raised if:
-@@ -1734,7 +1733,6 @@ static void bfq_remove_request(struct request_queue *q,
- 		BUG_ON(bfqq->meta_pending == 0);
- 		bfqq->meta_pending--;
- 	}
--	bfqg_stats_update_io_remove(bfqq_group(bfqq), rq->cmd_flags);
- }
- 
- static bool bfq_bio_merge(struct blk_mq_hw_ctx *hctx, struct bio *bio)
-@@ -1879,6 +1877,7 @@ static void bfq_requests_merged(struct request_queue *q, struct request *rq,
- 		bfqq->next_rq = rq;
- 
- 	bfq_remove_request(q, next);
-+	bfqg_stats_update_io_remove(bfqq_group(bfqq), next->cmd_flags);
- 
- 	spin_unlock_irq(&bfqq->bfqd->lock);
- end:
-@@ -4077,6 +4076,10 @@ static struct request *bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
- 	spin_lock_irq(&bfqd->lock);
- 
- 	rq = __bfq_dispatch_request(hctx);
-+	if (rq && RQ_BFQQ(rq))
-+		bfqg_stats_update_io_remove(bfqq_group(RQ_BFQQ(rq)),
-+					    rq->cmd_flags);
-+
- 	spin_unlock_irq(&bfqd->lock);
- 
- 	return rq;
-@@ -4634,6 +4637,7 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
- {
- 	struct request_queue *q = hctx->queue;
- 	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq);
- 
- 	spin_lock_irq(&bfqd->lock);
- 	if (blk_mq_sched_try_insert_merge(q, rq)) {
-@@ -4647,8 +4651,6 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
- 
- 	spin_lock_irq(&bfqd->lock);
- 	if (at_head || blk_rq_is_passthrough(rq)) {
--		struct bfq_queue *bfqq = RQ_BFQQ(rq);
--
- 		if (at_head)
- 			list_add(&rq->queuelist, &bfqd->dispatch);
- 		else
-@@ -4668,6 +4670,12 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
- 		rq->rq_flags &= ~RQF_GOT;
- 
- 		__bfq_insert_request(bfqd, rq);
-+		/*
-+		 * Update bfqq, because, if a queue merge has occurred
-+		 * in __bfq_insert_request, then rq has been
-+		 * redirected into a new queue.
-+		 */
-+		bfqq = RQ_BFQQ(rq);
- 
- 		if (rq_mergeable(rq)) {
- 			elv_rqhash_add(q, rq);
-@@ -4676,6 +4684,9 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
- 		}
- 	}
- 
-+	if (bfqq)
-+		bfqg_stats_update_io_add(bfqq_group(bfqq), bfqq, rq->cmd_flags);
-+
- 	spin_unlock_irq(&bfqd->lock);
- }
- 
-@@ -4893,8 +4904,11 @@ static void bfq_finish_request(struct request *rq)
- 		BUG_ON(in_interrupt());
- 
- 		assert_spin_locked(&bfqd->lock);
--		if (!RB_EMPTY_NODE(&rq->rb_node))
-+		if (!RB_EMPTY_NODE(&rq->rb_node)) {
- 			bfq_remove_request(rq->q, rq);
-+			bfqg_stats_update_io_remove(bfqq_group(bfqq),
-+						    rq->cmd_flags);
-+		}
- 		bfq_put_rq_priv_body(bfqq);
- 	}
- 
-
-From 8659a1549d2bf241129a0f7c90429bddd9c2bc53 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Wed, 8 Nov 2017 19:07:40 +0100
-Subject: [PATCH 50/51] block, bfq-mq: update blkio stats outside the scheduler
- lock
-
-bfq-mq invokes various blkg_*stats_* functions to update the statistics
-contained in the special files blkio.bfq-mq.* in the blkio controller
-groups, i.e., the I/O accounting related to the proportional-share
-policy provided by bfq-mq. The execution of these functions takes a
-considerable percentage, about 40%, of the total per-request execution
-time of bfq-mq (i.e., of the sum of the execution time of all the bfq-mq
-functions that have to be executed to process an I/O request from its
-creation to its destruction).  This reduces the request-processing
-rate sustainable by bfq-mq noticeably, even on a multicore CPU. In fact,
-the bfq-mq functions that invoke blkg_*stats_* functions cannot be
-executed in parallel with the rest of the code of bfq-mq, because
-both are executed under the same same per-device scheduler lock.
-
-To reduce this slowdown, this commit moves, wherever possible, the
-invocation of these functions (more precisely, of the bfq-mq functions
-that invoke blkg_*stats_* functions) outside the critical sections
-protected by the scheduler lock.
-
-With this change, and with all blkio.bfq-mq.* statistics enabled, the
-throughput grows, e.g., from 250 to 310 KIOPS (+25%) on an Intel
-i7-4850HQ, in case of 8 threads doing random I/O in parallel on
-null_blk, with the latter configured with 0 latency. We obtained the
-same or higher throughput boosts, up to +30%, with other processors
-(some figures are reported in the documentation). For our tests, we
-used the script [1], with which our results can be easily reproduced.
-
-NOTE. This commit still protects the invocation of blkg_*stats_*
-functions with the request_queue lock, because the group these
-functions are invoked on may otherwise disappear before or while these
-functions are executed.  Fortunately, tests without even this lock
-show, by difference, that the serialization caused by this lock has a
-little impact (at most ~5% of throughput reduction).
-
-[1] https://github.com/Algodev-github/IOSpeed
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
-Signed-off-by: Luca Miccio <lucmiccio@gmail.com>
----
- Documentation/block/bfq-iosched.txt |  18 ++++--
- block/bfq-mq-iosched.c              | 112 +++++++++++++++++++++++++++++++-----
- block/bfq-sched.c                   |   2 +
- 3 files changed, 112 insertions(+), 20 deletions(-)
-
-diff --git a/Documentation/block/bfq-iosched.txt b/Documentation/block/bfq-iosched.txt
-index 595ff7a5ff34..c816c595082d 100644
---- a/Documentation/block/bfq-iosched.txt
-+++ b/Documentation/block/bfq-iosched.txt
-@@ -31,16 +31,22 @@ latency and throughput, or on how to maximize throughput.
- 
- BFQ has a non-null overhead, which limits the maximum IOPS that the
- CPU can process for a device scheduled with BFQ. To give an idea of
--the limits on slow or average CPUs, here are BFQ limits for three
--different CPUs, on, respectively, an average laptop, an old desktop,
--and a cheap embedded system, in case full hierarchical support is
--enabled (i.e., CONFIG_BFQ_SQ_GROUP_IOSCHED is set for bfq-sq, or
--CONFIG_MQ_BFQ_GROUP_IOSCHED is set for bfq-mq, or, finally,
--CONFIG_BFQ_GROUP_IOSCHED is set for bfq):
-+the limits on slow or average CPUs, here are, first, the limits of
-+bfq-sq for three different CPUs, on, respectively, an average laptop,
-+an old desktop, and a cheap embedded system, in case full hierarchical
-+support is enabled (i.e., CONFIG_BFQ_SQ_GROUP_IOSCHED is set):
- - Intel i7-4850HQ: 250 KIOPS
- - AMD A8-3850: 170 KIOPS
- - ARM CortexTM-A53 Octa-core: 45 KIOPS
- 
-+bfq-mq and bfq instances reach, instead, a higher sustainable
-+throughput. Their limits, on the same systems as above, are, with full
-+hierarchical support enabled (i.e., CONFIG_MQ_BFQ_GROUP_IOSCHED set
-+for bfq-mq, or CONFIG_BFQ_GROUP_IOSCHED set for bfq):
-+- Intel i7-4850HQ: 310 KIOPS
-+- AMD A8-3850: 200 KIOPS
-+- ARM CortexTM-A53 Octa-core: 56 KIOPS
-+
- BFQ works for multi-queue devices too (bfq and bfq-mq instances).
- 
- The table of contents follows. Impatients can just jump to Section 3.
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index fbf28804c220..ab3b83d612c2 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -1822,7 +1822,7 @@ static void bfq_request_merged(struct request_queue *q, struct request *req,
- 		bfqq->next_rq = next_rq;
- 
- 		bfq_log_bfqq(bfqd, bfqq,
--			"requests_merged: req %p prev %p next_rq %p bfqq %p",
-+			"request_merged: req %p prev %p next_rq %p bfqq %p",
- 			     req, prev, next_rq, bfqq);
- 
- 		/*
-@@ -2415,7 +2415,6 @@ static void __bfq_set_in_service_queue(struct bfq_data *bfqd,
- 				       struct bfq_queue *bfqq)
- {
- 	if (bfqq) {
--		bfqg_stats_update_avg_queue_size(bfqq_group(bfqq));
- 		bfq_clear_bfqq_fifo_expire(bfqq);
- 
- 		bfqd->budgets_assigned = (bfqd->budgets_assigned*7 + 256) / 8;
-@@ -3784,7 +3783,6 @@ static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd)
- 				 */
- 				bfq_clear_bfqq_wait_request(bfqq);
- 				hrtimer_try_to_cancel(&bfqd->idle_slice_timer);
--				bfqg_stats_update_idle_time(bfqq_group(bfqq));
- 			}
- 			goto keep_queue;
- 		}
-@@ -4072,16 +4070,67 @@ static struct request *bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
- {
- 	struct bfq_data *bfqd = hctx->queue->elevator->elevator_data;
- 	struct request *rq;
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	struct bfq_queue *in_serv_queue, *bfqq;
-+	bool waiting_rq, idle_timer_disabled;
-+#endif
- 
- 	spin_lock_irq(&bfqd->lock);
- 
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	in_serv_queue = bfqd->in_service_queue;
-+	waiting_rq = in_serv_queue && bfq_bfqq_wait_request(in_serv_queue);
-+
- 	rq = __bfq_dispatch_request(hctx);
--	if (rq && RQ_BFQQ(rq))
--		bfqg_stats_update_io_remove(bfqq_group(RQ_BFQQ(rq)),
--					    rq->cmd_flags);
- 
-+	idle_timer_disabled =
-+		waiting_rq && !bfq_bfqq_wait_request(in_serv_queue);
-+
-+#else
-+	rq = __bfq_dispatch_request(hctx);
-+#endif
- 	spin_unlock_irq(&bfqd->lock);
- 
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	bfqq = rq ? RQ_BFQQ(rq) : NULL;
-+	if (!idle_timer_disabled && !bfqq)
-+		return rq;
-+
-+	/*
-+	 * rq and bfqq are guaranteed to exist until this function
-+	 * ends, for the following reasons. First, rq can be
-+	 * dispatched to the device, and then can be completed and
-+	 * freed, only after this function ends. Second, rq cannot be
-+	 * merged (and thus freed because of a merge) any longer,
-+	 * because it has already started. Thus rq cannot be freed
-+	 * before this function ends, and, since rq has a reference to
-+	 * bfqq, the same guarantee holds for bfqq too.
-+	 *
-+	 * In addition, the following queue lock guarantees that
-+	 * bfqq_group(bfqq) exists as well.
-+	 */
-+	spin_lock_irq(hctx->queue->queue_lock);
-+	if (idle_timer_disabled)
-+		/*
-+		 * Since the idle timer has been disabled,
-+		 * in_serv_queue contained some request when
-+		 * __bfq_dispatch_request was invoked above, which
-+		 * implies that rq was picked exactly from
-+		 * in_serv_queue. Thus in_serv_queue == bfqq, and is
-+		 * therefore guaranteed to exist because of the above
-+		 * arguments.
-+		 */
-+		bfqg_stats_update_idle_time(bfqq_group(in_serv_queue));
-+	if (bfqq) {
-+		struct bfq_group *bfqg = bfqq_group(bfqq);
-+
-+		bfqg_stats_update_avg_queue_size(bfqg);
-+		bfqg_stats_set_start_empty_time(bfqg);
-+		bfqg_stats_update_io_remove(bfqg, rq->cmd_flags);
-+	}
-+	spin_unlock_irq(hctx->queue->queue_lock);
-+#endif
-+
- 	return rq;
- }
- 
-@@ -4200,7 +4249,6 @@ static void bfq_exit_icq_bfqq(struct bfq_io_cq *bic, bool is_sync)
- 		unsigned long flags;
- 
- 		spin_lock_irqsave(&bfqd->lock, flags);
--
- 		bfq_exit_bfqq(bfqd, bfqq);
- 		bic_set_bfqq(bic, NULL, is_sync);
- 		spin_unlock_irqrestore(&bfqd->lock, flags);
-@@ -4554,7 +4602,6 @@ static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 		 */
- 		bfq_clear_bfqq_wait_request(bfqq);
- 		hrtimer_try_to_cancel(&bfqd->idle_slice_timer);
--		bfqg_stats_update_idle_time(bfqq_group(bfqq));
- 
- 		/*
- 		 * The queue is not empty, because a new request just
-@@ -4569,9 +4616,11 @@ static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 	}
- }
- 
--static void __bfq_insert_request(struct bfq_data *bfqd, struct request *rq)
-+/* returns true if it causes the idle timer to be disabled */
-+static bool __bfq_insert_request(struct bfq_data *bfqd, struct request *rq)
- {
- 	struct bfq_queue *bfqq = RQ_BFQQ(rq), *new_bfqq;
-+	bool waiting, idle_timer_disabled = false;
- 	BUG_ON(!bfqq);
- 
- 	assert_spin_locked(&bfqd->lock);
-@@ -4624,12 +4673,16 @@ static void __bfq_insert_request(struct bfq_data *bfqd, struct request *rq)
- 		}
- 	}
- 
-+	waiting = bfqq && bfq_bfqq_wait_request(bfqq);
- 	bfq_add_request(rq);
-+	idle_timer_disabled = waiting && !bfq_bfqq_wait_request(bfqq);
- 
- 	rq->fifo_time = ktime_get_ns() + bfqd->bfq_fifo_expire[rq_is_sync(rq)];
- 	list_add_tail(&rq->queuelist, &bfqq->fifo);
- 
- 	bfq_rq_enqueued(bfqd, bfqq, rq);
-+
-+	return idle_timer_disabled;
- }
- 
- static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
-@@ -4638,6 +4691,10 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
- 	struct request_queue *q = hctx->queue;
- 	struct bfq_data *bfqd = q->elevator->elevator_data;
- 	struct bfq_queue *bfqq = RQ_BFQQ(rq);
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	bool idle_timer_disabled = false;
-+	unsigned int cmd_flags;
-+#endif
- 
- 	spin_lock_irq(&bfqd->lock);
- 	if (blk_mq_sched_try_insert_merge(q, rq)) {
-@@ -4669,13 +4726,17 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
- 		BUG_ON(!(rq->rq_flags & RQF_GOT));
- 		rq->rq_flags &= ~RQF_GOT;
- 
--		__bfq_insert_request(bfqd, rq);
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+		idle_timer_disabled = __bfq_insert_request(bfqd, rq);
- 		/*
- 		 * Update bfqq, because, if a queue merge has occurred
- 		 * in __bfq_insert_request, then rq has been
- 		 * redirected into a new queue.
- 		 */
- 		bfqq = RQ_BFQQ(rq);
-+#else
-+		__bfq_insert_request(bfqd, rq);
-+#endif
- 
- 		if (rq_mergeable(rq)) {
- 			elv_rqhash_add(q, rq);
-@@ -4683,11 +4744,34 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
- 				q->last_merge = rq;
- 		}
- 	}
--
--	if (bfqq)
--		bfqg_stats_update_io_add(bfqq_group(bfqq), bfqq, rq->cmd_flags);
--
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	/*
-+	 * Cache cmd_flags before releasing scheduler lock, because rq
-+	 * may disappear afterwards (for example, because of a request
-+	 * merge).
-+	 */
-+	cmd_flags = rq->cmd_flags;
-+#endif
- 	spin_unlock_irq(&bfqd->lock);
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	if (!bfqq)
-+		return;
-+	/*
-+	 * bfqq still exists, because it can disappear only after
-+	 * either it is merged with another queue, or the process it
-+	 * is associated with exits. But both actions must be taken by
-+	 * the same process currently executing this flow of
-+	 * instruction.
-+	 *
-+	 * In addition, the following queue lock guarantees that
-+	 * bfqq_group(bfqq) exists as well.
-+	 */
-+	spin_lock_irq(q->queue_lock);
-+	bfqg_stats_update_io_add(bfqq_group(bfqq), bfqq, cmd_flags);
-+	if (idle_timer_disabled)
-+		bfqg_stats_update_idle_time(bfqq_group(bfqq));
-+	spin_unlock_irq(q->queue_lock);
-+#endif
- }
- 
- static void bfq_insert_requests(struct blk_mq_hw_ctx *hctx,
-diff --git a/block/bfq-sched.c b/block/bfq-sched.c
-index e4a2553a2d2c..616c0692335a 100644
---- a/block/bfq-sched.c
-+++ b/block/bfq-sched.c
-@@ -949,9 +949,11 @@ static void bfq_bfqq_served(struct bfq_queue *bfqq, int served)
- 		st->vtime += bfq_delta(served, st->wsum);
- 		bfq_forget_idle(st);
- 	}
-+#ifndef BFQ_MQ
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	bfqg_stats_set_start_empty_time(bfqq_group(bfqq));
- #endif
-+#endif
- 	st = bfq_entity_service_tree(&bfqq->entity);
- 	bfq_log_bfqq(bfqq->bfqd, bfqq, "bfqq_served %d secs, vtime %llu on %p",
- 		     served,  ((st->vtime>>10)*1000)>>12, st);
-
-From abdfb33a3325df55ec0261fd824ca61ddac13575 Mon Sep 17 00:00:00 2001
-From: Luca Miccio <lucmiccio@gmail.com>
-Date: Wed, 8 Nov 2017 19:07:41 +0100
-Subject: [PATCH 51/51] block, bfq-sq, bfq-mq: move debug blkio stats behind
- CONFIG_DEBUG_BLK_CGROUP
-
-BFQ (both bfq-mq and bfq-sq) currently creates, and updates, its own
-instance of the whole set of blkio statistics that cfq creates. Yet,
-from the comments of Tejun Heo in [1], it turned out that most of
-these statistics are meant/useful only for debugging. This commit
-makes BFQ create the latter, debugging statistics only if the option
-CONFIG_DEBUG_BLK_CGROUP is set.
-
-By doing so, this commit also enables BFQ to enjoy a high perfomance
-boost. The reason is that, if CONFIG_DEBUG_BLK_CGROUP is not set, then
-BFQ has to update far fewer statistics, and, in particular, not the
-heaviest to update.  To give an idea of the benefits, if
-CONFIG_DEBUG_BLK_CGROUP is not set, then, on an Intel i7-4850HQ, and
-with 8 threads doing random I/O in parallel on null_blk (configured
-with 0 latency), the throughput of bfq-mq grows from 310 to 400 KIOPS
-(+30%). We have measured similar or even much higher boosts with other
-CPUs: e.g., +45% with an ARM CortexTM-A53 Octa-core. Our results have
-been obtained and can be reproduced very easily with the script in [1].
-
-[1] https://www.spinics.net/lists/linux-block/msg18943.html
-
-Reported-by: Tejun Heo <tj@kernel.org>
-Signed-off-by: Luca Miccio <lucmiccio@gmail.com>
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- Documentation/block/bfq-iosched.txt |  59 ++++++++++---
- block/bfq-cgroup-included.c         | 163 ++++++++++++++++++++----------------
- block/bfq-mq-iosched.c              |  14 ++--
- block/bfq-mq.h                      |   4 +-
- block/bfq.h                         |   4 +-
- 5 files changed, 147 insertions(+), 97 deletions(-)
-
-diff --git a/Documentation/block/bfq-iosched.txt b/Documentation/block/bfq-iosched.txt
-index c816c595082d..30ef2dba85ad 100644
---- a/Documentation/block/bfq-iosched.txt
-+++ b/Documentation/block/bfq-iosched.txt
-@@ -29,24 +29,41 @@ for that device, by setting low_latency to 0. See Section 3 for
- details on how to configure BFQ for the desired tradeoff between
- latency and throughput, or on how to maximize throughput.
- 
--BFQ has a non-null overhead, which limits the maximum IOPS that the
--CPU can process for a device scheduled with BFQ. To give an idea of
--the limits on slow or average CPUs, here are, first, the limits of
--bfq-sq for three different CPUs, on, respectively, an average laptop,
-+BFQ has a non-null overhead, which limits the maximum IOPS that a CPU
-+can process for a device scheduled with BFQ. To give an idea of the
-+limits on slow or average CPUs, here are, first, the limits of bfq-mq
-+and bfq for three different CPUs, on, respectively, an average laptop,
- an old desktop, and a cheap embedded system, in case full hierarchical
--support is enabled (i.e., CONFIG_BFQ_SQ_GROUP_IOSCHED is set):
--- Intel i7-4850HQ: 250 KIOPS
--- AMD A8-3850: 170 KIOPS
--- ARM CortexTM-A53 Octa-core: 45 KIOPS
--
--bfq-mq and bfq instances reach, instead, a higher sustainable
--throughput. Their limits, on the same systems as above, are, with full
--hierarchical support enabled (i.e., CONFIG_MQ_BFQ_GROUP_IOSCHED set
--for bfq-mq, or CONFIG_BFQ_GROUP_IOSCHED set for bfq):
-+support is enabled (i.e., CONFIG_MQ_BFQ_GROUP_IOSCHED is set for
-+bfq-mq, or CONFIG_BFQ_GROUP_IOSCHED is set for bfq), but
-+CONFIG_DEBUG_BLK_CGROUP is not set (Section 4-2):
-+- Intel i7-4850HQ: 400 KIOPS
-+- AMD A8-3850: 250 KIOPS
-+- ARM CortexTM-A53 Octa-core: 80 KIOPS
-+
-+As for bfq-sq, it cannot reach the above IOPS, because of the
-+inherent, lower parallelism of legacy blk and of the components within
-+it (including bfq-sq itself). In particular, results with
-+CONFIG_DEBUG_BLK_CGROUP unset are rather fluctuating. The limits
-+reported below for the case CONFIG_DEBUG_BLK_CGROUP set will however
-+provide a lower bound to the limits of bfq-sq.
-+
-+Turning back to bfq-mq and bfq, If CONFIG_DEBUG_BLK_CGROUP is set (and
-+of course full hierarchical support is enabled), then the sustainable
-+throughput with bfq-mq and bfq decreases, because all blkio.bfq*
-+statistics are created and updated (Section 4-2).  For bfq-mq and bfq,
-+this leads to the following maximum sustainable throughputs, on the
-+same systems as above:
- - Intel i7-4850HQ: 310 KIOPS
- - AMD A8-3850: 200 KIOPS
- - ARM CortexTM-A53 Octa-core: 56 KIOPS
- 
-+Finally, if CONFIG_DEBUG_BLK_CGROUP is set (and full hierarchical
-+support is enabled), then bfq-sq exhibits the following limits:
-+- Intel i7-4850HQ: 250 KIOPS
-+- AMD A8-3850: 170 KIOPS
-+- ARM CortexTM-A53 Octa-core: 45 KIOPS
-+
- BFQ works for multi-queue devices too (bfq and bfq-mq instances).
- 
- The table of contents follows. Impatients can just jump to Section 3.
-@@ -524,6 +541,22 @@ BFQ-specific files is "blkio.bfqX." or "io.bfqX.", where X can be ""
- to set the weight of a group with the mainline BFQ is blkio.bfq.weight
- or io.bfq.weight.
- 
-+As for cgroups-v1 (blkio controller), the exact set of stat files
-+created, and kept up-to-date by bfq*, depends on whether
-+CONFIG_DEBUG_BLK_CGROUP is set. If it is set, then bfq* creates all
-+the stat files documented in
-+Documentation/cgroup-v1/blkio-controller.txt. If, instead,
-+CONFIG_DEBUG_BLK_CGROUP is not set, then bfq* creates only the files
-+blkio.bfq*.io_service_bytes
-+blkio.bfq*.io_service_bytes_recursive
-+blkio.bfq*.io_serviced
-+blkio.bfq*.io_serviced_recursive
-+
-+The value of CONFIG_DEBUG_BLK_CGROUP greatly influences the maximum
-+throughput sustainable with bfq*, because updating the blkio.bfq*
-+stats is rather costly, especially for some of the stats enabled by
-+CONFIG_DEBUG_BLK_CGROUP.
-+
- Parameters to set
- -----------------
- 
-diff --git a/block/bfq-cgroup-included.c b/block/bfq-cgroup-included.c
-index 631e53d9150d..562b0ce581a7 100644
---- a/block/bfq-cgroup-included.c
-+++ b/block/bfq-cgroup-included.c
-@@ -15,7 +15,7 @@
-  * file.
-  */
- 
--#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+#if defined(BFQ_GROUP_IOSCHED_ENABLED) && defined(CONFIG_DEBUG_BLK_CGROUP)
- 
- /* bfqg stats flags */
- enum bfqg_stats_flags {
-@@ -155,6 +155,63 @@ static void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg)
- 	bfqg_stats_update_group_wait_time(stats);
- }
- 
-+static void bfqg_stats_update_io_add(struct bfq_group *bfqg,
-+				struct bfq_queue *bfqq, unsigned int op)
-+{
-+	blkg_rwstat_add(&bfqg->stats.queued, op, 1);
-+	bfqg_stats_end_empty_time(&bfqg->stats);
-+	if (!(bfqq == ((struct bfq_data *)bfqg->bfqd)->in_service_queue))
-+		bfqg_stats_set_start_group_wait_time(bfqg, bfqq_group(bfqq));
-+}
-+
-+static void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op)
-+{
-+	blkg_rwstat_add(&bfqg->stats.queued, op, -1);
-+}
-+
-+static void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op)
-+{
-+	blkg_rwstat_add(&bfqg->stats.merged, op, 1);
-+}
-+
-+static void bfqg_stats_update_completion(struct bfq_group *bfqg,
-+		uint64_t start_time, uint64_t io_start_time, unsigned int op)
-+{
-+	struct bfqg_stats *stats = &bfqg->stats;
-+	unsigned long long now = sched_clock();
-+
-+	if (time_after64(now, io_start_time))
-+		blkg_rwstat_add(&stats->service_time, op,
-+				now - io_start_time);
-+	if (time_after64(io_start_time, start_time))
-+		blkg_rwstat_add(&stats->wait_time, op,
-+				io_start_time - start_time);
-+}
-+
-+#else /* BFQ_GROUP_IOSCHED_ENABLED && CONFIG_DEBUG_BLK_CGROUP */
-+
-+static inline void bfqg_stats_update_io_add(struct bfq_group *bfqg,
-+			struct bfq_queue *bfqq, unsigned int op) { }
-+static inline void
-+bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op) { }
-+static inline void
-+bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op) { }
-+static inline void bfqg_stats_update_completion(struct bfq_group *bfqg,
-+		uint64_t start_time, uint64_t io_start_time,
-+		unsigned int op) { }
-+static inline void
-+bfqg_stats_set_start_group_wait_time(struct bfq_group *bfqg,
-+		struct bfq_group *curr_bfqg) { }
-+static inline void bfqg_stats_end_empty_time(struct bfqg_stats *stats) { }
-+static inline void bfqg_stats_update_dequeue(struct bfq_group *bfqg) { }
-+static inline void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg) { }
-+static inline void bfqg_stats_update_idle_time(struct bfq_group *bfqg) { }
-+static inline void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg) { }
-+static inline void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg) { }
-+
-+#endif /* BFQ_GROUP_IOSCHED_ENABLED && CONFIG_DEBUG_BLK_CGROUP */
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- static struct blkcg_policy blkcg_policy_bfq;
- 
- /*
-@@ -247,44 +304,10 @@ static void bfqg_and_blkg_put(struct bfq_group *bfqg)
- }
- #endif
- 
--static void bfqg_stats_update_io_add(struct bfq_group *bfqg,
--				     struct bfq_queue *bfqq,
--				     unsigned int op)
--{
--	blkg_rwstat_add(&bfqg->stats.queued, op, 1);
--	bfqg_stats_end_empty_time(&bfqg->stats);
--	if (!(bfqq == ((struct bfq_data *)bfqg->bfqd)->in_service_queue))
--		bfqg_stats_set_start_group_wait_time(bfqg, bfqq_group(bfqq));
--}
--
--static void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op)
--{
--	blkg_rwstat_add(&bfqg->stats.queued, op, -1);
--}
--
--static void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op)
--{
--	blkg_rwstat_add(&bfqg->stats.merged, op, 1);
--}
--
--static void bfqg_stats_update_completion(struct bfq_group *bfqg,
--			uint64_t start_time, uint64_t io_start_time,
--			unsigned int op)
--{
--	struct bfqg_stats *stats = &bfqg->stats;
--	unsigned long long now = sched_clock();
--
--	if (time_after64(now, io_start_time))
--		blkg_rwstat_add(&stats->service_time, op,
--				now - io_start_time);
--	if (time_after64(io_start_time, start_time))
--		blkg_rwstat_add(&stats->wait_time, op,
--				io_start_time - start_time);
--}
--
- /* @stats = 0 */
- static void bfqg_stats_reset(struct bfqg_stats *stats)
- {
-+#ifdef CONFIG_DEBUG_BLK_CGROUP
- 	/* queued stats shouldn't be cleared */
- 	blkg_rwstat_reset(&stats->merged);
- 	blkg_rwstat_reset(&stats->service_time);
-@@ -296,6 +319,7 @@ static void bfqg_stats_reset(struct bfqg_stats *stats)
- 	blkg_stat_reset(&stats->group_wait_time);
- 	blkg_stat_reset(&stats->idle_time);
- 	blkg_stat_reset(&stats->empty_time);
-+#endif
- }
- 
- /* @to += @from */
-@@ -304,6 +328,7 @@ static void bfqg_stats_add_aux(struct bfqg_stats *to, struct bfqg_stats *from)
- 	if (!to || !from)
- 		return;
- 
-+#ifdef CONFIG_DEBUG_BLK_CGROUP
- 	/* queued stats shouldn't be cleared */
- 	blkg_rwstat_add_aux(&to->merged, &from->merged);
- 	blkg_rwstat_add_aux(&to->service_time, &from->service_time);
-@@ -316,6 +341,7 @@ static void bfqg_stats_add_aux(struct bfqg_stats *to, struct bfqg_stats *from)
- 	blkg_stat_add_aux(&to->group_wait_time, &from->group_wait_time);
- 	blkg_stat_add_aux(&to->idle_time, &from->idle_time);
- 	blkg_stat_add_aux(&to->empty_time, &from->empty_time);
-+#endif
- }
- 
- /*
-@@ -367,6 +393,7 @@ static void bfq_init_entity(struct bfq_entity *entity,
- 
- static void bfqg_stats_exit(struct bfqg_stats *stats)
- {
-+#ifdef CONFIG_DEBUG_BLK_CGROUP
- 	blkg_rwstat_exit(&stats->merged);
- 	blkg_rwstat_exit(&stats->service_time);
- 	blkg_rwstat_exit(&stats->wait_time);
-@@ -378,10 +405,12 @@ static void bfqg_stats_exit(struct bfqg_stats *stats)
- 	blkg_stat_exit(&stats->group_wait_time);
- 	blkg_stat_exit(&stats->idle_time);
- 	blkg_stat_exit(&stats->empty_time);
-+#endif
- }
- 
- static int bfqg_stats_init(struct bfqg_stats *stats, gfp_t gfp)
- {
-+#ifdef CONFIG_DEBUG_BLK_CGROUP
- 	if (blkg_rwstat_init(&stats->merged, gfp) ||
- 	    blkg_rwstat_init(&stats->service_time, gfp) ||
- 	    blkg_rwstat_init(&stats->wait_time, gfp) ||
-@@ -396,6 +425,7 @@ static int bfqg_stats_init(struct bfqg_stats *stats, gfp_t gfp)
- 		bfqg_stats_exit(stats);
- 		return -ENOMEM;
- 	}
-+#endif
- 
- 	return 0;
- }
-@@ -1003,6 +1033,7 @@ static ssize_t bfq_io_set_weight(struct kernfs_open_file *of,
- 	return bfq_io_set_weight_legacy(of_css(of), NULL, weight);
- }
- 
-+#ifdef CONFIG_DEBUG_BLK_CGROUP
- static int bfqg_print_stat(struct seq_file *sf, void *v)
- {
- 	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_stat,
-@@ -1108,6 +1139,7 @@ static int bfqg_print_avg_queue_size(struct seq_file *sf, void *v)
- 			  0, false);
- 	return 0;
- }
-+#endif /* CONFIG_DEBUG_BLK_CGROUP */
- 
- static struct bfq_group *
- bfq_create_group_hierarchy(struct bfq_data *bfqd, int node)
-@@ -1137,15 +1169,6 @@ static struct cftype bfq_blkcg_legacy_files[] = {
- 
- 	/* statistics, covers only the tasks in the bfqg */
- 	{
--		.name = BFQ_CGROUP_FNAME(time),
--		.private = offsetof(struct bfq_group, stats.time),
--		.seq_show = bfqg_print_stat,
--	},
--	{
--		.name = BFQ_CGROUP_FNAME(sectors),
--		.seq_show = bfqg_print_stat_sectors,
--	},
--	{
- 		.name = BFQ_CGROUP_FNAME(io_service_bytes),
- 		.private = (unsigned long)&blkcg_policy_bfq,
- 		.seq_show = blkg_print_stat_bytes,
-@@ -1155,6 +1178,16 @@ static struct cftype bfq_blkcg_legacy_files[] = {
- 		.private = (unsigned long)&blkcg_policy_bfq,
- 		.seq_show = blkg_print_stat_ios,
- 	},
-+#ifdef CONFIG_DEBUG_BLK_CGROUP
-+	{
-+		.name = BFQ_CGROUP_FNAME(time),
-+		.private = offsetof(struct bfq_group, stats.time),
-+		.seq_show = bfqg_print_stat,
-+	},
-+	{
-+		.name = BFQ_CGROUP_FNAME(sectors),
-+		.seq_show = bfqg_print_stat_sectors,
-+	},
- 	{
- 		.name = BFQ_CGROUP_FNAME(io_service_time),
- 		.private = offsetof(struct bfq_group, stats.service_time),
-@@ -1175,18 +1208,10 @@ static struct cftype bfq_blkcg_legacy_files[] = {
- 		.private = offsetof(struct bfq_group, stats.queued),
- 		.seq_show = bfqg_print_rwstat,
- 	},
-+#endif /* CONFIG_DEBUG_BLK_CGROUP */
- 
- 	/* the same statictics which cover the bfqg and its descendants */
- 	{
--		.name = BFQ_CGROUP_FNAME(time_recursive),
--		.private = offsetof(struct bfq_group, stats.time),
--		.seq_show = bfqg_print_stat_recursive,
--	},
--	{
--		.name = BFQ_CGROUP_FNAME(sectors_recursive),
--		.seq_show = bfqg_print_stat_sectors_recursive,
--	},
--	{
- 		.name = BFQ_CGROUP_FNAME(io_service_bytes_recursive),
- 		.private = (unsigned long)&blkcg_policy_bfq,
- 		.seq_show = blkg_print_stat_bytes_recursive,
-@@ -1196,6 +1221,16 @@ static struct cftype bfq_blkcg_legacy_files[] = {
- 		.private = (unsigned long)&blkcg_policy_bfq,
- 		.seq_show = blkg_print_stat_ios_recursive,
- 	},
-+#ifdef CONFIG_DEBUG_BLK_CGROUP
-+	{
-+		.name = BFQ_CGROUP_FNAME(time_recursive),
-+		.private = offsetof(struct bfq_group, stats.time),
-+		.seq_show = bfqg_print_stat_recursive,
-+	},
-+	{
-+		.name = BFQ_CGROUP_FNAME(sectors_recursive),
-+		.seq_show = bfqg_print_stat_sectors_recursive,
-+	},
- 	{
- 		.name = BFQ_CGROUP_FNAME(io_service_time_recursive),
- 		.private = offsetof(struct bfq_group, stats.service_time),
-@@ -1240,6 +1275,7 @@ static struct cftype bfq_blkcg_legacy_files[] = {
- 		.private = offsetof(struct bfq_group, stats.dequeue),
- 		.seq_show = bfqg_print_stat,
- 	},
-+#endif	/* CONFIG_DEBUG_BLK_CGROUP */
- 	{ }	/* terminate */
- };
- 
-@@ -1257,25 +1293,6 @@ static struct cftype bfq_blkg_files[] = {
- 
- #else /* BFQ_GROUP_IOSCHED_ENABLED */
- 
--static inline void bfqg_stats_update_io_add(struct bfq_group *bfqg,
--			struct bfq_queue *bfqq, unsigned int op) { }
--static inline void
--bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op) { }
--static inline void
--bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op) { }
--static inline void bfqg_stats_update_completion(struct bfq_group *bfqg,
--			uint64_t start_time, uint64_t io_start_time,
--			unsigned int op) { }
--static inline void
--bfqg_stats_set_start_group_wait_time(struct bfq_group *bfqg,
--				     struct bfq_group *curr_bfqg) { }
--static inline void bfqg_stats_end_empty_time(struct bfqg_stats *stats) { }
--static inline void bfqg_stats_update_dequeue(struct bfq_group *bfqg) { }
--static inline void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg) { }
--static inline void bfqg_stats_update_idle_time(struct bfq_group *bfqg) { }
--static inline void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg) { }
--static inline void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg) { }
--
- static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 			  struct bfq_group *bfqg) {}
- 
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index ab3b83d612c2..0c09609a6099 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -4070,14 +4070,14 @@ static struct request *bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
- {
- 	struct bfq_data *bfqd = hctx->queue->elevator->elevator_data;
- 	struct request *rq;
--#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+#if defined(BFQ_GROUP_IOSCHED_ENABLED) &&  defined(CONFIG_DEBUG_BLK_CGROUP)
- 	struct bfq_queue *in_serv_queue, *bfqq;
- 	bool waiting_rq, idle_timer_disabled;
- #endif
- 
- 	spin_lock_irq(&bfqd->lock);
- 
--#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+#if defined(BFQ_GROUP_IOSCHED_ENABLED) &&  defined(CONFIG_DEBUG_BLK_CGROUP)
- 	in_serv_queue = bfqd->in_service_queue;
- 	waiting_rq = in_serv_queue && bfq_bfqq_wait_request(in_serv_queue);
- 
-@@ -4091,7 +4091,7 @@ static struct request *bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
- #endif
- 	spin_unlock_irq(&bfqd->lock);
- 
--#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+#if defined(BFQ_GROUP_IOSCHED_ENABLED) &&  defined(CONFIG_DEBUG_BLK_CGROUP)
- 	bfqq = rq ? RQ_BFQQ(rq) : NULL;
- 	if (!idle_timer_disabled && !bfqq)
- 		return rq;
-@@ -4691,7 +4691,7 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
- 	struct request_queue *q = hctx->queue;
- 	struct bfq_data *bfqd = q->elevator->elevator_data;
- 	struct bfq_queue *bfqq = RQ_BFQQ(rq);
--#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+#if defined(BFQ_GROUP_IOSCHED_ENABLED) &&  defined(CONFIG_DEBUG_BLK_CGROUP)
- 	bool idle_timer_disabled = false;
- 	unsigned int cmd_flags;
- #endif
-@@ -4726,7 +4726,7 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
- 		BUG_ON(!(rq->rq_flags & RQF_GOT));
- 		rq->rq_flags &= ~RQF_GOT;
- 
--#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+#if defined(BFQ_GROUP_IOSCHED_ENABLED) &&  defined(CONFIG_DEBUG_BLK_CGROUP)
- 		idle_timer_disabled = __bfq_insert_request(bfqd, rq);
- 		/*
- 		 * Update bfqq, because, if a queue merge has occurred
-@@ -4744,7 +4744,7 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
- 				q->last_merge = rq;
- 		}
- 	}
--#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+#if defined(BFQ_GROUP_IOSCHED_ENABLED) &&  defined(CONFIG_DEBUG_BLK_CGROUP)
- 	/*
- 	 * Cache cmd_flags before releasing scheduler lock, because rq
- 	 * may disappear afterwards (for example, because of a request
-@@ -4753,7 +4753,7 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
- 	cmd_flags = rq->cmd_flags;
- #endif
- 	spin_unlock_irq(&bfqd->lock);
--#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+#if defined(BFQ_GROUP_IOSCHED_ENABLED) &&  defined(CONFIG_DEBUG_BLK_CGROUP)
- 	if (!bfqq)
- 		return;
- 	/*
-diff --git a/block/bfq-mq.h b/block/bfq-mq.h
-index 7ed2cc29be57..1cb05bb853d2 100644
---- a/block/bfq-mq.h
-+++ b/block/bfq-mq.h
-@@ -784,7 +784,7 @@ enum bfqq_expiration {
- 
- 
- struct bfqg_stats {
--#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+#if defined(BFQ_GROUP_IOSCHED_ENABLED) &&  defined(CONFIG_DEBUG_BLK_CGROUP)
- 	/* number of ios merged */
- 	struct blkg_rwstat		merged;
- 	/* total time spent on device in ns, may not be accurate w/ queueing */
-@@ -812,7 +812,7 @@ struct bfqg_stats {
- 	uint64_t			start_idle_time;
- 	uint64_t			start_empty_time;
- 	uint16_t			flags;
--#endif
-+#endif /* BFQ_GROUP_IOSCHED_ENABLED && CONFIG_DEBUG_BLK_CGROUP */
- };
- 
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
-diff --git a/block/bfq.h b/block/bfq.h
-index 15d326f466b7..47cd4d5a8c32 100644
---- a/block/bfq.h
-+++ b/block/bfq.h
-@@ -791,7 +791,7 @@ enum bfqq_expiration {
- 
- 
- struct bfqg_stats {
--#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+#if defined(BFQ_GROUP_IOSCHED_ENABLED) &&  defined(CONFIG_DEBUG_BLK_CGROUP)
- 	/* number of ios merged */
- 	struct blkg_rwstat		merged;
- 	/* total time spent on device in ns, may not be accurate w/ queueing */
-@@ -819,7 +819,7 @@ struct bfqg_stats {
- 	uint64_t			start_idle_time;
- 	uint64_t			start_empty_time;
- 	uint16_t			flags;
--#endif
-+#endif /* BFQ_GROUP_IOSCHED_ENABLED && CONFIG_DEBUG_BLK_CGROUP */
- };
- 
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
diff --git a/sys-kernel/linux-image-redcore-lts/files/4.14-0002-BFQ-v8r12-20180404.patch b/sys-kernel/linux-image-redcore-lts/files/4.14-0002-BFQ-v8r12-20180404.patch
deleted file mode 100644
index 104325d6..00000000
--- a/sys-kernel/linux-image-redcore-lts/files/4.14-0002-BFQ-v8r12-20180404.patch
+++ /dev/null
@@ -1,4611 +0,0 @@
-From 7bd365a925748767d7ed807e5498f90bae0ebc25 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Tue, 14 Nov 2017 08:28:45 +0100
-Subject: [PATCH 01/23] block, bfq-mq: turn BUG_ON on request-size into WARN_ON
-
-BFQ has many checks of internal and external consistency. One of them
-checks that an I/O request has still sectors to serve, if it happens
-to be retired without being served. If the request has no sector to
-serve, a BUG_ON signals the failure and causes the kernel to
-terminate. Yet, from a crash report by a user [1], this condition may
-happen to hold, in apparently correct functioning, for I/O with a
-CD/DVD.
-
-To address this issue, this commit turns the above BUG_ON into a
-WARN_ON. This commit also adds a companion WARN_ON on request
-insertion into the scheduler.
-
-[1] https://groups.google.com/d/msg/bfq-iosched/DDOTJBroBa4/VyU1zUFtCgAJ
-
-Reported-by: Alexandre Frade <admfrade@gmail.com>
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-mq-iosched.c | 4 +++-
- 1 file changed, 3 insertions(+), 1 deletion(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 0c09609a6099..0fc757ae7a42 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -1540,6 +1540,8 @@ static void bfq_add_request(struct request *rq)
- 
- 	BUG_ON(!RQ_BFQQ(rq));
- 	BUG_ON(RQ_BFQQ(rq) != bfqq);
-+	WARN_ON(blk_rq_sectors(rq) == 0);
-+
- 	elv_rb_add(&bfqq->sort_list, rq);
- 
- 	/*
-@@ -4962,7 +4964,7 @@ static void bfq_finish_request(struct request *rq)
- 					     rq_io_start_time_ns(rq),
- 					     rq->cmd_flags);
- 
--	BUG_ON(blk_rq_sectors(rq) == 0 && !(rq->rq_flags & RQF_STARTED));
-+	WARN_ON(blk_rq_sectors(rq) == 0 && !(rq->rq_flags & RQF_STARTED));
- 
- 	if (likely(rq->rq_flags & RQF_STARTED)) {
- 		unsigned long flags;
-
-From 1097d368a20456c88acd75b3184c68df38e8f7b8 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Sun, 12 Nov 2017 22:43:46 +0100
-Subject: [PATCH 02/23] block, bfq-sq, bfq-mq: consider also past I/O in soft
- real-time detection
-
-BFQ privileges the I/O of soft real-time applications, such as video
-players, to guarantee to these application a high bandwidth and a low
-latency. In this respect, it is not easy to correctly detect when an
-application is soft real-time. A particularly nasty false positive is
-that of an I/O-bound application that occasionally happens to meet all
-requirements to be deemed as soft real-time. After being detected as
-soft real-time, such an application monopolizes the device. Fortunately,
-BFQ will realize soon that the application is actually not soft
-real-time and suspend every privilege. Yet, the application may happen
-again to be wrongly detected as soft real-time, and so on.
-
-As highlighted by our tests, this problem causes BFQ to occasionally
-fail to guarantee a high responsiveness, in the presence of heavy
-background I/O workloads. The reason is that the background workload
-happens to be detected as soft real-time, more or less frequently,
-during the execution of the interactive task under test. To give an
-idea, because of this problem, Libreoffice Writer occasionally takes 8
-seconds, instead of 3, to start up, if there are sequential reads and
-writes in the background, on a Kingston SSDNow V300.
-
-This commit addresses this issue by leveraging the following facts.
-
-The reason why some applications are detected as soft real-time despite
-all BFQ checks to avoid false positives, is simply that, during high
-CPU or storage-device load, I/O-bound applications may happen to do
-I/O slowly enough to meet all soft real-time requirements, and pass
-all BFQ extra checks. Yet, this happens only for limited time periods:
-slow-speed time intervals are usually interspersed between other time
-intervals during which these applications do I/O at a very high speed.
-To exploit these facts, this commit introduces a little change, in the
-detection of soft real-time behavior, to systematically consider also
-the recent past: the higher the speed was in the recent past, the
-later next I/O should arrive for the application to be considered as
-soft real-time. At the beginning of a slow-speed interval, the minimum
-arrival time allowed for the next I/O usually happens to still be so
-high, to fall *after* the end of the slow-speed period itself. As a
-consequence, the application does not risk to be deemed as soft
-real-time during the slow-speed interval. Then, during the next
-high-speed interval, the application cannot, evidently, be deemed as
-soft real-time (exactly because of its speed), and so on.
-
-This extra filtering proved to be rather effective: in the above test,
-the frequency of false positives became so low that the start-up time
-was 3 seconds in all iterations (apart from occasional outliers,
-caused by page-cache-management issues, which are out of the scope of
-this commit, and cannot be solved by an I/O scheduler).
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
-Signed-off-by: Angelo Ruocco <angeloruocco90@gmail.com>
----
- block/bfq-mq-iosched.c | 115 ++++++++++++++++++++++++++++++++++---------------
- block/bfq-sq-iosched.c | 115 ++++++++++++++++++++++++++++++++++---------------
- 2 files changed, 162 insertions(+), 68 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 0fc757ae7a42..4d06d900f45e 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -3201,37 +3201,78 @@ static bool bfq_bfqq_is_slow(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-  * whereas soft_rt_next_start is set to infinity for applications that do
-  * not.
-  *
-- * Unfortunately, even a greedy application may happen to behave in an
-- * isochronous way if the CPU load is high. In fact, the application may
-- * stop issuing requests while the CPUs are busy serving other processes,
-- * then restart, then stop again for a while, and so on. In addition, if
-- * the disk achieves a low enough throughput with the request pattern
-- * issued by the application (e.g., because the request pattern is random
-- * and/or the device is slow), then the application may meet the above
-- * bandwidth requirement too. To prevent such a greedy application to be
-- * deemed as soft real-time, a further rule is used in the computation of
-- * soft_rt_next_start: soft_rt_next_start must be higher than the current
-- * time plus the maximum time for which the arrival of a request is waited
-- * for when a sync queue becomes idle, namely bfqd->bfq_slice_idle.
-- * This filters out greedy applications, as the latter issue instead their
-- * next request as soon as possible after the last one has been completed
-- * (in contrast, when a batch of requests is completed, a soft real-time
-- * application spends some time processing data).
-+ * Unfortunately, even a greedy (i.e., I/O-bound) application may
-+ * happen to meet, occasionally or systematically, both the above
-+ * bandwidth and isochrony requirements. This may happen at least in
-+ * the following circumstances. First, if the CPU load is high. The
-+ * application may stop issuing requests while the CPUs are busy
-+ * serving other processes, then restart, then stop again for a while,
-+ * and so on. The other circumstances are related to the storage
-+ * device: the storage device is highly loaded or reaches a low-enough
-+ * throughput with the I/O of the application (e.g., because the I/O
-+ * is random and/or the device is slow). In all these cases, the
-+ * I/O of the application may be simply slowed down enough to meet
-+ * the bandwidth and isochrony requirements. To reduce the probability
-+ * that greedy applications are deemed as soft real-time in these
-+ * corner cases, a further rule is used in the computation of
-+ * soft_rt_next_start: the return value of this function is forced to
-+ * be higher than the maximum between the following two quantities.
-  *
-- * Unfortunately, the last filter may easily generate false positives if
-- * only bfqd->bfq_slice_idle is used as a reference time interval and one
-- * or both the following cases occur:
-- * 1) HZ is so low that the duration of a jiffy is comparable to or higher
-- *    than bfqd->bfq_slice_idle. This happens, e.g., on slow devices with
-- *    HZ=100.
-+ * (a) Current time plus: (1) the maximum time for which the arrival
-+ *     of a request is waited for when a sync queue becomes idle,
-+ *     namely bfqd->bfq_slice_idle, and (2) a few extra jiffies. We
-+ *     postpone for a moment the reason for adding a few extra
-+ *     jiffies; we get back to it after next item (b).  Lower-bounding
-+ *     the return value of this function with the current time plus
-+ *     bfqd->bfq_slice_idle tends to filter out greedy applications,
-+ *     because the latter issue their next request as soon as possible
-+ *     after the last one has been completed. In contrast, a soft
-+ *     real-time application spends some time processing data, after a
-+ *     batch of its requests has been completed.
-+ *
-+ * (b) Current value of bfqq->soft_rt_next_start. As pointed out
-+ *     above, greedy applications may happen to meet both the
-+ *     bandwidth and isochrony requirements under heavy CPU or
-+ *     storage-device load. In more detail, in these scenarios, these
-+ *     applications happen, only for limited time periods, to do I/O
-+ *     slowly enough to meet all the requirements described so far,
-+ *     including the filtering in above item (a). These slow-speed
-+ *     time intervals are usually interspersed between other time
-+ *     intervals during which these applications do I/O at a very high
-+ *     speed. Fortunately, exactly because of the high speed of the
-+ *     I/O in the high-speed intervals, the values returned by this
-+ *     function happen to be so high, near the end of any such
-+ *     high-speed interval, to be likely to fall *after* the end of
-+ *     the low-speed time interval that follows. These high values are
-+ *     stored in bfqq->soft_rt_next_start after each invocation of
-+ *     this function. As a consequence, if the last value of
-+ *     bfqq->soft_rt_next_start is constantly used to lower-bound the
-+ *     next value that this function may return, then, from the very
-+ *     beginning of a low-speed interval, bfqq->soft_rt_next_start is
-+ *     likely to be constantly kept so high that any I/O request
-+ *     issued during the low-speed interval is considered as arriving
-+ *     to soon for the application to be deemed as soft
-+ *     real-time. Then, in the high-speed interval that follows, the
-+ *     application will not be deemed as soft real-time, just because
-+ *     it will do I/O at a high speed. And so on.
-+ *
-+ * Getting back to the filtering in item (a), in the following two
-+ * cases this filtering might be easily passed by a greedy
-+ * application, if the reference quantity was just
-+ * bfqd->bfq_slice_idle:
-+ * 1) HZ is so low that the duration of a jiffy is comparable to or
-+ *    higher than bfqd->bfq_slice_idle. This happens, e.g., on slow
-+ *    devices with HZ=100. The time granularity may be so coarse
-+ *    that the approximation, in jiffies, of bfqd->bfq_slice_idle
-+ *    is rather lower than the exact value.
-  * 2) jiffies, instead of increasing at a constant rate, may stop increasing
-  *    for a while, then suddenly 'jump' by several units to recover the lost
-  *    increments. This seems to happen, e.g., inside virtual machines.
-- * To address this issue, we do not use as a reference time interval just
-- * bfqd->bfq_slice_idle, but bfqd->bfq_slice_idle plus a few jiffies. In
-- * particular we add the minimum number of jiffies for which the filter
-- * seems to be quite precise also in embedded systems and KVM/QEMU virtual
-- * machines.
-+ * To address this issue, in the filtering in (a) we do not use as a
-+ * reference time interval just bfqd->bfq_slice_idle, but
-+ * bfqd->bfq_slice_idle plus a few jiffies. In particular, we add the
-+ * minimum number of jiffies for which the filter seems to be quite
-+ * precise also in embedded systems and KVM/QEMU virtual machines.
-  */
- static unsigned long bfq_bfqq_softrt_next_start(struct bfq_data *bfqd,
- 						struct bfq_queue *bfqq)
-@@ -3243,10 +3284,11 @@ static unsigned long bfq_bfqq_softrt_next_start(struct bfq_data *bfqd,
- 		     jiffies_to_msecs(HZ * bfqq->service_from_backlogged /
- 				      bfqd->bfq_wr_max_softrt_rate));
- 
--	return max(bfqq->last_idle_bklogged +
--		   HZ * bfqq->service_from_backlogged /
--		   bfqd->bfq_wr_max_softrt_rate,
--		   jiffies + nsecs_to_jiffies(bfqq->bfqd->bfq_slice_idle) + 4);
-+	return max3(bfqq->soft_rt_next_start,
-+		    bfqq->last_idle_bklogged +
-+		    HZ * bfqq->service_from_backlogged /
-+		    bfqd->bfq_wr_max_softrt_rate,
-+		    jiffies + nsecs_to_jiffies(bfqq->bfqd->bfq_slice_idle) + 4);
- }
- 
- /**
-@@ -4395,10 +4437,15 @@ static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 	bfqq->split_time = bfq_smallest_from_now();
- 
- 	/*
--	 * Set to the value for which bfqq will not be deemed as
--	 * soft rt when it becomes backlogged.
-+	 * To not forget the possibly high bandwidth consumed by a
-+	 * process/queue in the recent past,
-+	 * bfq_bfqq_softrt_next_start() returns a value at least equal
-+	 * to the current value of bfqq->soft_rt_next_start (see
-+	 * comments on bfq_bfqq_softrt_next_start).  Set
-+	 * soft_rt_next_start to now, to mean that bfqq has consumed
-+	 * no bandwidth so far.
- 	 */
--	bfqq->soft_rt_next_start = bfq_greatest_from_now();
-+	bfqq->soft_rt_next_start = jiffies;
- 
- 	/* first request is almost certainly seeky */
- 	bfqq->seek_history = 1;
-diff --git a/block/bfq-sq-iosched.c b/block/bfq-sq-iosched.c
-index 4bbd7f4c0154..987dc255c82c 100644
---- a/block/bfq-sq-iosched.c
-+++ b/block/bfq-sq-iosched.c
-@@ -3089,37 +3089,78 @@ static bool bfq_bfqq_is_slow(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-  * whereas soft_rt_next_start is set to infinity for applications that do
-  * not.
-  *
-- * Unfortunately, even a greedy application may happen to behave in an
-- * isochronous way if the CPU load is high. In fact, the application may
-- * stop issuing requests while the CPUs are busy serving other processes,
-- * then restart, then stop again for a while, and so on. In addition, if
-- * the disk achieves a low enough throughput with the request pattern
-- * issued by the application (e.g., because the request pattern is random
-- * and/or the device is slow), then the application may meet the above
-- * bandwidth requirement too. To prevent such a greedy application to be
-- * deemed as soft real-time, a further rule is used in the computation of
-- * soft_rt_next_start: soft_rt_next_start must be higher than the current
-- * time plus the maximum time for which the arrival of a request is waited
-- * for when a sync queue becomes idle, namely bfqd->bfq_slice_idle.
-- * This filters out greedy applications, as the latter issue instead their
-- * next request as soon as possible after the last one has been completed
-- * (in contrast, when a batch of requests is completed, a soft real-time
-- * application spends some time processing data).
-+ * Unfortunately, even a greedy (i.e., I/O-bound) application may
-+ * happen to meet, occasionally or systematically, both the above
-+ * bandwidth and isochrony requirements. This may happen at least in
-+ * the following circumstances. First, if the CPU load is high. The
-+ * application may stop issuing requests while the CPUs are busy
-+ * serving other processes, then restart, then stop again for a while,
-+ * and so on. The other circumstances are related to the storage
-+ * device: the storage device is highly loaded or reaches a low-enough
-+ * throughput with the I/O of the application (e.g., because the I/O
-+ * is random and/or the device is slow). In all these cases, the
-+ * I/O of the application may be simply slowed down enough to meet
-+ * the bandwidth and isochrony requirements. To reduce the probability
-+ * that greedy applications are deemed as soft real-time in these
-+ * corner cases, a further rule is used in the computation of
-+ * soft_rt_next_start: the return value of this function is forced to
-+ * be higher than the maximum between the following two quantities.
-  *
-- * Unfortunately, the last filter may easily generate false positives if
-- * only bfqd->bfq_slice_idle is used as a reference time interval and one
-- * or both the following cases occur:
-- * 1) HZ is so low that the duration of a jiffy is comparable to or higher
-- *    than bfqd->bfq_slice_idle. This happens, e.g., on slow devices with
-- *    HZ=100.
-+ * (a) Current time plus: (1) the maximum time for which the arrival
-+ *     of a request is waited for when a sync queue becomes idle,
-+ *     namely bfqd->bfq_slice_idle, and (2) a few extra jiffies. We
-+ *     postpone for a moment the reason for adding a few extra
-+ *     jiffies; we get back to it after next item (b).  Lower-bounding
-+ *     the return value of this function with the current time plus
-+ *     bfqd->bfq_slice_idle tends to filter out greedy applications,
-+ *     because the latter issue their next request as soon as possible
-+ *     after the last one has been completed. In contrast, a soft
-+ *     real-time application spends some time processing data, after a
-+ *     batch of its requests has been completed.
-+ *
-+ * (b) Current value of bfqq->soft_rt_next_start. As pointed out
-+ *     above, greedy applications may happen to meet both the
-+ *     bandwidth and isochrony requirements under heavy CPU or
-+ *     storage-device load. In more detail, in these scenarios, these
-+ *     applications happen, only for limited time periods, to do I/O
-+ *     slowly enough to meet all the requirements described so far,
-+ *     including the filtering in above item (a). These slow-speed
-+ *     time intervals are usually interspersed between other time
-+ *     intervals during which these applications do I/O at a very high
-+ *     speed. Fortunately, exactly because of the high speed of the
-+ *     I/O in the high-speed intervals, the values returned by this
-+ *     function happen to be so high, near the end of any such
-+ *     high-speed interval, to be likely to fall *after* the end of
-+ *     the low-speed time interval that follows. These high values are
-+ *     stored in bfqq->soft_rt_next_start after each invocation of
-+ *     this function. As a consequence, if the last value of
-+ *     bfqq->soft_rt_next_start is constantly used to lower-bound the
-+ *     next value that this function may return, then, from the very
-+ *     beginning of a low-speed interval, bfqq->soft_rt_next_start is
-+ *     likely to be constantly kept so high that any I/O request
-+ *     issued during the low-speed interval is considered as arriving
-+ *     to soon for the application to be deemed as soft
-+ *     real-time. Then, in the high-speed interval that follows, the
-+ *     application will not be deemed as soft real-time, just because
-+ *     it will do I/O at a high speed. And so on.
-+ *
-+ * Getting back to the filtering in item (a), in the following two
-+ * cases this filtering might be easily passed by a greedy
-+ * application, if the reference quantity was just
-+ * bfqd->bfq_slice_idle:
-+ * 1) HZ is so low that the duration of a jiffy is comparable to or
-+ *    higher than bfqd->bfq_slice_idle. This happens, e.g., on slow
-+ *    devices with HZ=100. The time granularity may be so coarse
-+ *    that the approximation, in jiffies, of bfqd->bfq_slice_idle
-+ *    is rather lower than the exact value.
-  * 2) jiffies, instead of increasing at a constant rate, may stop increasing
-  *    for a while, then suddenly 'jump' by several units to recover the lost
-  *    increments. This seems to happen, e.g., inside virtual machines.
-- * To address this issue, we do not use as a reference time interval just
-- * bfqd->bfq_slice_idle, but bfqd->bfq_slice_idle plus a few jiffies. In
-- * particular we add the minimum number of jiffies for which the filter
-- * seems to be quite precise also in embedded systems and KVM/QEMU virtual
-- * machines.
-+ * To address this issue, in the filtering in (a) we do not use as a
-+ * reference time interval just bfqd->bfq_slice_idle, but
-+ * bfqd->bfq_slice_idle plus a few jiffies. In particular, we add the
-+ * minimum number of jiffies for which the filter seems to be quite
-+ * precise also in embedded systems and KVM/QEMU virtual machines.
-  */
- static unsigned long bfq_bfqq_softrt_next_start(struct bfq_data *bfqd,
- 						struct bfq_queue *bfqq)
-@@ -3131,10 +3172,11 @@ static unsigned long bfq_bfqq_softrt_next_start(struct bfq_data *bfqd,
- 		     jiffies_to_msecs(HZ * bfqq->service_from_backlogged /
- 				      bfqd->bfq_wr_max_softrt_rate));
- 
--	return max(bfqq->last_idle_bklogged +
--		   HZ * bfqq->service_from_backlogged /
--		   bfqd->bfq_wr_max_softrt_rate,
--		   jiffies + nsecs_to_jiffies(bfqq->bfqd->bfq_slice_idle) + 4);
-+	return max3(bfqq->soft_rt_next_start,
-+		    bfqq->last_idle_bklogged +
-+		    HZ * bfqq->service_from_backlogged /
-+		    bfqd->bfq_wr_max_softrt_rate,
-+		    jiffies + nsecs_to_jiffies(bfqq->bfqd->bfq_slice_idle) + 4);
- }
- 
- /**
-@@ -4167,10 +4209,15 @@ static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 	bfqq->split_time = bfq_smallest_from_now();
- 
- 	/*
--	 * Set to the value for which bfqq will not be deemed as
--	 * soft rt when it becomes backlogged.
-+	 * To not forget the possibly high bandwidth consumed by a
-+	 * process/queue in the recent past,
-+	 * bfq_bfqq_softrt_next_start() returns a value at least equal
-+	 * to the current value of bfqq->soft_rt_next_start (see
-+	 * comments on bfq_bfqq_softrt_next_start).  Set
-+	 * soft_rt_next_start to now, to mean that bfqq has consumed
-+	 * no bandwidth so far.
- 	 */
--	bfqq->soft_rt_next_start = bfq_greatest_from_now();
-+	bfqq->soft_rt_next_start = jiffies;
- 
- 	/* first request is almost certainly seeky */
- 	bfqq->seek_history = 1;
-
-From 2a09b505660c81dbb80a5d68c9bc558c326d041f Mon Sep 17 00:00:00 2001
-From: Chiara Bruschi <bruschi.chiara@outlook.it>
-Date: Thu, 7 Dec 2017 09:57:19 +0100
-Subject: [PATCH 03/23] block, bfq-mq: fix occurrences of request
- prepare/finish methods' old names
-
-Commits 'b01f1fa3bb19' (Port of "blk-mq-sched: unify request prepare
-methods") and 'cc10d2d7d2c1' (Port of "blk-mq-sched: unify request
-finished methods") changed the old names of current bfq_prepare_request
-and bfq_finish_request methods, but left them unchanged elsewhere in
-the code (related comments, part of function name bfq_put_rq_priv_body).
-
-This commit fixes every occurrence of the old names of these methods
-by changing them into the current names.
-
-Fixes: b01f1fa3bb19 (Port of "blk-mq-sched: unify request prepare methods")
-Fixes: cc10d2d7d2c1 (Port of "blk-mq-sched: unify request finished methods")
-Reviewed-by: Paolo Valente <paolo.valente@linaro.org>
-Signed-off-by: Federico Motta <federico@willer.it>
-Signed-off-by: Chiara Bruschi <bruschi.chiara@outlook.it>
----
- block/bfq-mq-iosched.c | 38 +++++++++++++++++++-------------------
- 1 file changed, 19 insertions(+), 19 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 4d06d900f45e..8f8d5eccb016 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -4018,20 +4018,20 @@ static struct request *__bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
- 			/*
- 			 * TESTING: reset DISP_LIST flag, because: 1)
- 			 * this rq this request has passed through
--			 * get_rq_private, 2) then it will have
--			 * put_rq_private invoked on it, and 3) in
--			 * put_rq_private we use this flag to check
--			 * that put_rq_private is not invoked on
--			 * requests for which get_rq_private has been
--			 * invoked.
-+			 * bfq_prepare_request, 2) then it will have
-+			 * bfq_finish_request invoked on it, and 3) in
-+			 * bfq_finish_request we use this flag to check
-+			 * that bfq_finish_request is not invoked on
-+			 * requests for which bfq_prepare_request has
-+			 * been invoked.
- 			 */
- 			rq->rq_flags &= ~RQF_DISP_LIST;
- 			goto inc_in_driver_start_rq;
- 		}
- 
- 		/*
--		 * We exploit the put_rq_private hook to decrement
--		 * rq_in_driver, but put_rq_private will not be
-+		 * We exploit the bfq_finish_request hook to decrement
-+		 * rq_in_driver, but bfq_finish_request will not be
- 		 * invoked on this request. So, to avoid unbalance,
- 		 * just start this request, without incrementing
- 		 * rq_in_driver. As a negative consequence,
-@@ -4040,14 +4040,14 @@ static struct request *__bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
- 		 * bfq_schedule_dispatch to be invoked uselessly.
- 		 *
- 		 * As for implementing an exact solution, the
--		 * put_request hook, if defined, is probably invoked
--		 * also on this request. So, by exploiting this hook,
--		 * we could 1) increment rq_in_driver here, and 2)
--		 * decrement it in put_request. Such a solution would
--		 * let the value of the counter be always accurate,
--		 * but it would entail using an extra interface
--		 * function. This cost seems higher than the benefit,
--		 * being the frequency of non-elevator-private
-+		 * bfq_finish_request hook, if defined, is probably
-+		 * invoked also on this request. So, by exploiting
-+		 * this hook, we could 1) increment rq_in_driver here,
-+		 * and 2) decrement it in bfq_finish_request. Such a
-+		 * solution would let the value of the counter be
-+		 * always accurate, but it would entail using an extra
-+		 * interface function. This cost seems higher than the
-+		 * benefit, being the frequency of non-elevator-private
- 		 * requests very low.
- 		 */
- 		goto start_rq;
-@@ -4963,7 +4963,7 @@ static void bfq_completed_request(struct bfq_queue *bfqq, struct bfq_data *bfqd)
- 	}
- }
- 
--static void bfq_put_rq_priv_body(struct bfq_queue *bfqq)
-+static void bfq_finish_request_body(struct bfq_queue *bfqq)
- {
- 	bfq_log_bfqq(bfqq->bfqd, bfqq,
- 		     "put_request_body: allocated %d", bfqq->allocated);
-@@ -5019,7 +5019,7 @@ static void bfq_finish_request(struct request *rq)
- 		spin_lock_irqsave(&bfqd->lock, flags);
- 
- 		bfq_completed_request(bfqq, bfqd);
--		bfq_put_rq_priv_body(bfqq);
-+		bfq_finish_request_body(bfqq);
- 
- 		spin_unlock_irqrestore(&bfqd->lock, flags);
- 	} else {
-@@ -5042,7 +5042,7 @@ static void bfq_finish_request(struct request *rq)
- 			bfqg_stats_update_io_remove(bfqq_group(bfqq),
- 						    rq->cmd_flags);
- 		}
--		bfq_put_rq_priv_body(bfqq);
-+		bfq_finish_request_body(bfqq);
- 	}
- 
- 	rq->elv.priv[0] = NULL;
-
-From 4df19943c3a767df453abea3d2ac3433c3326ce0 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Thu, 16 Nov 2017 18:38:13 +0100
-Subject: [PATCH 04/23] block, bfq-sq, bfq-mq: add missing rq_pos_tree update
- on rq removal
-
-If two processes do I/O close to each other, then BFQ merges the
-bfq_queues associated with these processes, to get a more sequential
-I/O, and thus a higher throughput.  In this respect, to detect whether
-two processes are doing I/O close to each other, BFQ keeps a list of
-the head-of-line I/O requests of all active bfq_queues.  The list is
-ordered by initial sectors, and implemented through a red-black tree
-(rq_pos_tree).
-
-Unfortunately, the update of the rq_pos_tree was incomplete, because
-the tree was not updated on the removal of the head-of-line I/O
-request of a bfq_queue, in case the queue did not remain empty. This
-commit adds the missing update.
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
-Signed-off-by: Angelo Ruocco <angeloruocco90@gmail.com>
----
- block/bfq-mq-iosched.c | 3 +++
- block/bfq-sq-iosched.c | 3 +++
- 2 files changed, 6 insertions(+)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 8f8d5eccb016..603191c9008f 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -1729,6 +1729,9 @@ static void bfq_remove_request(struct request_queue *q,
- 			rb_erase(&bfqq->pos_node, bfqq->pos_root);
- 			bfqq->pos_root = NULL;
- 		}
-+	} else {
-+		BUG_ON(!bfqq->next_rq);
-+		bfq_pos_tree_add_move(bfqd, bfqq);
- 	}
- 
- 	if (rq->cmd_flags & REQ_META) {
-diff --git a/block/bfq-sq-iosched.c b/block/bfq-sq-iosched.c
-index 987dc255c82c..ea90ace79e49 100644
---- a/block/bfq-sq-iosched.c
-+++ b/block/bfq-sq-iosched.c
-@@ -1669,6 +1669,9 @@ static void bfq_remove_request(struct request *rq)
- 			rb_erase(&bfqq->pos_node, bfqq->pos_root);
- 			bfqq->pos_root = NULL;
- 		}
-+	} else {
-+		BUG_ON(!bfqq->next_rq);
-+		bfq_pos_tree_add_move(bfqd, bfqq);
- 	}
- 
- 	if (rq->cmd_flags & REQ_META) {
-
-From b844e345140aaea957d84a21d2aa67588b020cd5 Mon Sep 17 00:00:00 2001
-From: Angelo Ruocco <angeloruocco90@gmail.com>
-Date: Mon, 18 Dec 2017 08:28:08 +0100
-Subject: [PATCH 05/23] block, bfq-sq, bfq-mq: check low_latency flag in
- bfq_bfqq_save_state()
-
-A just-created bfq_queue will certainly be deemed as interactive on
-the arrival of its first I/O request, if the low_latency flag is
-set. Yet, if the queue is merged with another queue on the arrival of
-its first I/O request, it will not have the chance to be flagged as
-interactive. Nevertheless, if the queue is then split soon enough, it
-has to be flagged as interactive after the split.
-
-To handle this early-merge scenario correctly, BFQ saves the state of
-the queue, on the merge, as if the latter had already been deemed
-interactive. So, if the queue is split soon, it will get
-weight-raised, because the previous state of the queue is resumed on
-the split.
-
-Unfortunately, in the act of saving the state of the newly-created
-queue, BFQ doesn't check whether the low_latency flag is set, and this
-causes early-merged queues to be then weight-raised, on queue splits,
-even if low_latency is off. This commit addresses this problem by
-adding the missing check.
-
-Signed-off-by: Angelo Ruocco <angeloruocco90@gmail.com>
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-mq-iosched.c | 3 ++-
- block/bfq-sq-iosched.c | 3 ++-
- 2 files changed, 4 insertions(+), 2 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 603191c9008f..ff9776c8836a 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -2231,7 +2231,8 @@ static void bfq_bfqq_save_state(struct bfq_queue *bfqq)
- 	bic->saved_in_large_burst = bfq_bfqq_in_large_burst(bfqq);
- 	bic->was_in_burst_list = !hlist_unhashed(&bfqq->burst_list_node);
- 	if (unlikely(bfq_bfqq_just_created(bfqq) &&
--		     !bfq_bfqq_in_large_burst(bfqq))) {
-+		     !bfq_bfqq_in_large_burst(bfqq) &&
-+		     bfqq->bfqd->low_latency)) {
- 		/*
- 		 * bfqq being merged ritgh after being created: bfqq
- 		 * would have deserved interactive weight raising, but
-diff --git a/block/bfq-sq-iosched.c b/block/bfq-sq-iosched.c
-index ea90ace79e49..3a2d764e760c 100644
---- a/block/bfq-sq-iosched.c
-+++ b/block/bfq-sq-iosched.c
-@@ -2109,7 +2109,8 @@ static void bfq_bfqq_save_state(struct bfq_queue *bfqq)
- 	bic->saved_in_large_burst = bfq_bfqq_in_large_burst(bfqq);
- 	bic->was_in_burst_list = !hlist_unhashed(&bfqq->burst_list_node);
- 	if (unlikely(bfq_bfqq_just_created(bfqq) &&
--		     !bfq_bfqq_in_large_burst(bfqq))) {
-+		     !bfq_bfqq_in_large_burst(bfqq) &&
-+		     bfqq->bfqd->low_latency)) {
- 		/*
- 		 * bfqq being merged ritgh after being created: bfqq
- 		 * would have deserved interactive weight raising, but
-
-From 4cc6896fe1de2e0b4de151a6e70658f10b9ec2fa Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Fri, 27 Oct 2017 11:12:14 +0200
-Subject: [PATCH 06/23] block, bfq-sq, bfq-mq: let a queue be merged only
- shortly after starting I/O
-
-In BFQ and CFQ, two processes are said to be cooperating if they do
-I/O in such a way that the union of their I/O requests yields a
-sequential I/O pattern. To get such a sequential I/O pattern out of
-the non-sequential pattern of each cooperating process, BFQ and CFQ
-merge the queues associated with these processes. In more detail,
-cooperating processes, and thus their associated queues, usually
-start, or restart, to do I/O shortly after each other. This is the
-case, e.g., for the I/O threads of KVM/QEMU and of the dump
-utility. Basing on this assumption, this commit allows a bfq_queue to
-be merged only during a short time interval (100ms) after it starts,
-or re-starts, to do I/O.  This filtering provides two important
-benefits.
-
-First, it greatly reduces the probability that two non-cooperating
-processes have their queues merged by mistake, if they just happen to
-do I/O close to each other for a short time interval. These spurious
-merges cause loss of service guarantees. A low-weight bfq_queue may
-unjustly get more than its expected share of the throughput: if such a
-low-weight queue is merged with a high-weight queue, then the I/O for
-the low-weight queue is served as if the queue had a high weight. This
-may damage other high-weight queues unexpectedly.  For instance,
-because of this issue, lxterminal occasionally took 7.5 seconds to
-start, instead of 6.5 seconds, when some sequential readers and
-writers did I/O in the background on a FUJITSU MHX2300BT HDD.  The
-reason is that the bfq_queues associated with some of the readers or
-the writers were merged with the high-weight queues of some processes
-that had to do some urgent but little I/O. The readers then exploited
-the inherited high weight for all or most of their I/O, during the
-start-up of terminal. The filtering introduced by this commit
-eliminated any outlier caused by spurious queue merges in our start-up
-time tests.
-
-This filtering also provides a little boost of the throughput
-sustainable by BFQ: 3-4%, depending on the CPU. The reason is that,
-once a bfq_queue cannot be merged any longer, this commit makes BFQ
-stop updating the data needed to handle merging for the queue.
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
-Signed-off-by: Angelo Ruocco <angeloruocco90@gmail.com>
----
- block/bfq-mq-iosched.c | 64 +++++++++++++++++++++++++++++++++++++++++---------
- block/bfq-mq.h         |  1 +
- block/bfq-sched.c      |  4 ++++
- block/bfq-sq-iosched.c | 64 +++++++++++++++++++++++++++++++++++++++++---------
- block/bfq.h            |  2 ++
- 5 files changed, 113 insertions(+), 22 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index ff9776c8836a..8b17b25a3c30 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -119,6 +119,20 @@ static const int bfq_async_charge_factor = 10;
- /* Default timeout values, in jiffies, approximating CFQ defaults. */
- static const int bfq_timeout = (HZ / 8);
- 
-+/*
-+ * Time limit for merging (see comments in bfq_setup_cooperator). Set
-+ * to the slowest value that, in our tests, proved to be effective in
-+ * removing false positives, while not causing true positives to miss
-+ * queue merging.
-+ *
-+ * As can be deduced from the low time limit below, queue merging, if
-+ * successful, happens at the very beggining of the I/O of the involved
-+ * cooperating processes, as a consequence of the arrival of the very
-+ * first requests from each cooperator.  After that, there is very
-+ * little chance to find cooperators.
-+ */
-+static const unsigned long bfq_merge_time_limit = HZ/10;
-+
- static struct kmem_cache *bfq_pool;
- 
- /* Below this threshold (in ns), we consider thinktime immediate. */
-@@ -389,6 +403,13 @@ bfq_rq_pos_tree_lookup(struct bfq_data *bfqd, struct rb_root *root,
- 	return bfqq;
- }
- 
-+static bool bfq_too_late_for_merging(struct bfq_queue *bfqq)
-+{
-+	return bfqq->service_from_backlogged > 0 &&
-+		time_is_before_jiffies(bfqq->first_IO_time +
-+				       bfq_merge_time_limit);
-+}
-+
- static void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq)
- {
- 	struct rb_node **p, *parent;
-@@ -399,6 +420,14 @@ static void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq)
- 		bfqq->pos_root = NULL;
- 	}
- 
-+	/*
-+	 * bfqq cannot be merged any longer (see comments in
-+	 * bfq_setup_cooperator): no point in adding bfqq into the
-+	 * position tree.
-+	 */
-+	if (bfq_too_late_for_merging(bfqq))
-+		return;
-+
- 	if (bfq_class_idle(bfqq))
- 		return;
- 	if (!bfqq->next_rq)
-@@ -2081,6 +2110,13 @@ bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq)
- static bool bfq_may_be_close_cooperator(struct bfq_queue *bfqq,
- 					struct bfq_queue *new_bfqq)
- {
-+	if (bfq_too_late_for_merging(new_bfqq)) {
-+		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			     "[%s] too late for bfq%d to be merged",
-+			     __func__, new_bfqq->pid);
-+		return false;
-+	}
-+
- 	if (bfq_class_idle(bfqq) || bfq_class_idle(new_bfqq) ||
- 	    (bfqq->ioprio_class != new_bfqq->ioprio_class))
- 		return false;
-@@ -2149,6 +2185,23 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- {
- 	struct bfq_queue *in_service_bfqq, *new_bfqq;
- 
-+	/*
-+	 * Prevent bfqq from being merged if it has been created too
-+	 * long ago. The idea is that true cooperating processes, and
-+	 * thus their associated bfq_queues, are supposed to be
-+	 * created shortly after each other. This is the case, e.g.,
-+	 * for KVM/QEMU and dump I/O threads. Basing on this
-+	 * assumption, the following filtering greatly reduces the
-+	 * probability that two non-cooperating processes, which just
-+	 * happen to do close I/O for some short time interval, have
-+	 * their queues merged by mistake.
-+	 */
-+	if (bfq_too_late_for_merging(bfqq)) {
-+		bfq_log_bfqq(bfqd, bfqq,
-+			     "would have looked for coop, but too late");
-+		return NULL;
-+	}
-+
- 	if (bfqq->new_bfqq)
- 		return bfqq->new_bfqq;
- 
-@@ -3338,17 +3391,6 @@ static void bfq_bfqq_expire(struct bfq_data *bfqd,
- 	 */
- 	slow = bfq_bfqq_is_slow(bfqd, bfqq, compensate, reason, &delta);
- 
--	/*
--	 * Increase service_from_backlogged before next statement,
--	 * because the possible next invocation of
--	 * bfq_bfqq_charge_time would likely inflate
--	 * entity->service. In contrast, service_from_backlogged must
--	 * contain real service, to enable the soft real-time
--	 * heuristic to correctly compute the bandwidth consumed by
--	 * bfqq.
--	 */
--	bfqq->service_from_backlogged += entity->service;
--
- 	/*
- 	 * As above explained, charge slow (typically seeky) and
- 	 * timed-out queues with the time and not the service
-diff --git a/block/bfq-mq.h b/block/bfq-mq.h
-index 1cb05bb853d2..a5947b203ef2 100644
---- a/block/bfq-mq.h
-+++ b/block/bfq-mq.h
-@@ -337,6 +337,7 @@ struct bfq_queue {
- 	unsigned long wr_start_at_switch_to_srt;
- 
- 	unsigned long split_time; /* time of last split */
-+	unsigned long first_IO_time; /* time of first I/O for this queue */
- };
- 
- /**
-diff --git a/block/bfq-sched.c b/block/bfq-sched.c
-index 616c0692335a..9d261dd428e4 100644
---- a/block/bfq-sched.c
-+++ b/block/bfq-sched.c
-@@ -939,6 +939,10 @@ static void bfq_bfqq_served(struct bfq_queue *bfqq, int served)
- 	struct bfq_entity *entity = &bfqq->entity;
- 	struct bfq_service_tree *st;
- 
-+	if (!bfqq->service_from_backlogged)
-+		bfqq->first_IO_time = jiffies;
-+
-+	bfqq->service_from_backlogged += served;
- 	for_each_entity(entity) {
- 		st = bfq_entity_service_tree(entity);
- 
-diff --git a/block/bfq-sq-iosched.c b/block/bfq-sq-iosched.c
-index 3a2d764e760c..cd00a41ca35d 100644
---- a/block/bfq-sq-iosched.c
-+++ b/block/bfq-sq-iosched.c
-@@ -113,6 +113,20 @@ static const int bfq_async_charge_factor = 10;
- /* Default timeout values, in jiffies, approximating CFQ defaults. */
- static const int bfq_timeout = (HZ / 8);
- 
-+/*
-+ * Time limit for merging (see comments in bfq_setup_cooperator). Set
-+ * to the slowest value that, in our tests, proved to be effective in
-+ * removing false positives, while not causing true positives to miss
-+ * queue merging.
-+ *
-+ * As can be deduced from the low time limit below, queue merging, if
-+ * successful, happens at the very beggining of the I/O of the involved
-+ * cooperating processes, as a consequence of the arrival of the very
-+ * first requests from each cooperator.  After that, there is very
-+ * little chance to find cooperators.
-+ */
-+static const unsigned long bfq_merge_time_limit = HZ/10;
-+
- static struct kmem_cache *bfq_pool;
- 
- /* Below this threshold (in ns), we consider thinktime immediate. */
-@@ -351,6 +365,13 @@ bfq_rq_pos_tree_lookup(struct bfq_data *bfqd, struct rb_root *root,
- 	return bfqq;
- }
- 
-+static bool bfq_too_late_for_merging(struct bfq_queue *bfqq)
-+{
-+	return bfqq->service_from_backlogged > 0 &&
-+		time_is_before_jiffies(bfqq->first_IO_time +
-+				       bfq_merge_time_limit);
-+}
-+
- static void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq)
- {
- 	struct rb_node **p, *parent;
-@@ -361,6 +382,14 @@ static void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq)
- 		bfqq->pos_root = NULL;
- 	}
- 
-+	/*
-+	 * bfqq cannot be merged any longer (see comments in
-+	 * bfq_setup_cooperator): no point in adding bfqq into the
-+	 * position tree.
-+	 */
-+	if (bfq_too_late_for_merging(bfqq))
-+		return;
-+
- 	if (bfq_class_idle(bfqq))
- 		return;
- 	if (!bfqq->next_rq)
-@@ -1960,6 +1989,13 @@ bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq)
- static bool bfq_may_be_close_cooperator(struct bfq_queue *bfqq,
- 					struct bfq_queue *new_bfqq)
- {
-+	if (bfq_too_late_for_merging(new_bfqq)) {
-+		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			     "[%s] too late for bfq%d to be merged",
-+			     __func__, new_bfqq->pid);
-+		return false;
-+	}
-+
- 	if (bfq_class_idle(bfqq) || bfq_class_idle(new_bfqq) ||
- 	    (bfqq->ioprio_class != new_bfqq->ioprio_class))
- 		return false;
-@@ -2028,6 +2064,23 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- {
- 	struct bfq_queue *in_service_bfqq, *new_bfqq;
- 
-+	/*
-+	 * Prevent bfqq from being merged if it has been created too
-+	 * long ago. The idea is that true cooperating processes, and
-+	 * thus their associated bfq_queues, are supposed to be
-+	 * created shortly after each other. This is the case, e.g.,
-+	 * for KVM/QEMU and dump I/O threads. Basing on this
-+	 * assumption, the following filtering greatly reduces the
-+	 * probability that two non-cooperating processes, which just
-+	 * happen to do close I/O for some short time interval, have
-+	 * their queues merged by mistake.
-+	 */
-+	if (bfq_too_late_for_merging(bfqq)) {
-+		bfq_log_bfqq(bfqd, bfqq,
-+			     "would have looked for coop, but too late");
-+		return NULL;
-+	}
-+
- 	if (bfqq->new_bfqq)
- 		return bfqq->new_bfqq;
- 
-@@ -3226,17 +3279,6 @@ static void bfq_bfqq_expire(struct bfq_data *bfqd,
- 	 */
- 	slow = bfq_bfqq_is_slow(bfqd, bfqq, compensate, reason, &delta);
- 
--	/*
--	 * Increase service_from_backlogged before next statement,
--	 * because the possible next invocation of
--	 * bfq_bfqq_charge_time would likely inflate
--	 * entity->service. In contrast, service_from_backlogged must
--	 * contain real service, to enable the soft real-time
--	 * heuristic to correctly compute the bandwidth consumed by
--	 * bfqq.
--	 */
--	bfqq->service_from_backlogged += entity->service;
--
- 	/*
- 	 * As above explained, charge slow (typically seeky) and
- 	 * timed-out queues with the time and not the service
-diff --git a/block/bfq.h b/block/bfq.h
-index 47cd4d5a8c32..59539adc00a5 100644
---- a/block/bfq.h
-+++ b/block/bfq.h
-@@ -329,6 +329,8 @@ struct bfq_queue {
- 	unsigned long wr_start_at_switch_to_srt;
- 
- 	unsigned long split_time; /* time of last split */
-+
-+	unsigned long first_IO_time; /* time of first I/O for this queue */
- };
- 
- /**
-
-From 157f39c43ab182280634cd4f6335d0187b3741a0 Mon Sep 17 00:00:00 2001
-From: Angelo Ruocco <angeloruocco90@gmail.com>
-Date: Mon, 11 Dec 2017 14:19:54 +0100
-Subject: [PATCH 07/23] block, bfq-sq, bfq-mq: remove superfluous check in
- queue-merging setup
-
-When two or more processes do I/O in a way that the their requests are
-sequential in respect to one another, BFQ merges the bfq_queues associated
-with the processes. This way the overall I/O pattern becomes sequential,
-and thus there is a boost in througput.
-These cooperating processes usually start or restart to do I/O shortly
-after each other. So, in order to avoid merging non-cooperating processes,
-BFQ ensures that none of these queues has been in weight raising for too
-long.
-
-In this respect, from commit "block, bfq-sq, bfq-mq: let a queue be merged
-only shortly after being created", BFQ checks whether any queue (and not
-only weight-raised ones) is doing I/O continuously from too long to be
-merged.
-
-This new additional check makes the first one useless: a queue doing
-I/O from long enough, if being weight-raised, is also a queue in
-weight raising for too long to be merged. Accordingly, this commit
-removes the first check.
-
-Signed-off-by: Angelo Ruocco <angeloruocco90@gmail.com>
-Signed-off-by: Paolo Valente <paolo.valente@linaro.com>
----
- block/bfq-mq-iosched.c | 53 ++++----------------------------------------------
- block/bfq-sq-iosched.c | 53 ++++----------------------------------------------
- 2 files changed, 8 insertions(+), 98 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 8b17b25a3c30..f5db8613a70f 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -2140,20 +2140,6 @@ static bool bfq_may_be_close_cooperator(struct bfq_queue *bfqq,
- 	return true;
- }
- 
--/*
-- * If this function returns true, then bfqq cannot be merged. The idea
-- * is that true cooperation happens very early after processes start
-- * to do I/O. Usually, late cooperations are just accidental false
-- * positives. In case bfqq is weight-raised, such false positives
-- * would evidently degrade latency guarantees for bfqq.
-- */
--static bool wr_from_too_long(struct bfq_queue *bfqq)
--{
--	return bfqq->wr_coeff > 1 &&
--		time_is_before_jiffies(bfqq->last_wr_start_finish +
--				       msecs_to_jiffies(100));
--}
--
- /*
-  * Attempt to schedule a merge of bfqq with the currently in-service
-  * queue or with a close queue among the scheduled queues.  Return
-@@ -2167,11 +2153,6 @@ static bool wr_from_too_long(struct bfq_queue *bfqq)
-  * to maintain. Besides, in such a critical condition as an out of memory,
-  * the benefits of queue merging may be little relevant, or even negligible.
-  *
-- * Weight-raised queues can be merged only if their weight-raising
-- * period has just started. In fact cooperating processes are usually
-- * started together. Thus, with this filter we avoid false positives
-- * that would jeopardize low-latency guarantees.
-- *
-  * WARNING: queue merging may impair fairness among non-weight raised
-  * queues, for at least two reasons: 1) the original weight of a
-  * merged queue may change during the merged state, 2) even being the
-@@ -2205,15 +2186,7 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 	if (bfqq->new_bfqq)
- 		return bfqq->new_bfqq;
- 
--	if (io_struct && wr_from_too_long(bfqq) &&
--	    likely(bfqq != &bfqd->oom_bfqq))
--		bfq_log_bfqq(bfqd, bfqq,
--			     "would have looked for coop, but bfq%d wr",
--			bfqq->pid);
--
--	if (!io_struct ||
--	    wr_from_too_long(bfqq) ||
--	    unlikely(bfqq == &bfqd->oom_bfqq))
-+	if (!io_struct || unlikely(bfqq == &bfqd->oom_bfqq))
- 		return NULL;
- 
- 	/* If there is only one backlogged queue, don't search. */
-@@ -2223,17 +2196,8 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 	in_service_bfqq = bfqd->in_service_queue;
- 
- 	if (in_service_bfqq && in_service_bfqq != bfqq &&
--	    wr_from_too_long(in_service_bfqq)
--	    && likely(in_service_bfqq == &bfqd->oom_bfqq))
--		bfq_log_bfqq(bfqd, bfqq,
--		"would have tried merge with in-service-queue, but wr");
--
--	if (!in_service_bfqq || in_service_bfqq == bfqq
--	    || wr_from_too_long(in_service_bfqq) ||
--	    unlikely(in_service_bfqq == &bfqd->oom_bfqq))
--		goto check_scheduled;
--
--	if (bfq_rq_close_to_sector(io_struct, request, bfqd->last_position) &&
-+	    likely(in_service_bfqq != &bfqd->oom_bfqq) &&
-+	    bfq_rq_close_to_sector(io_struct, request, bfqd->last_position) &&
- 	    bfqq->entity.parent == in_service_bfqq->entity.parent &&
- 	    bfq_may_be_close_cooperator(bfqq, in_service_bfqq)) {
- 		new_bfqq = bfq_setup_merge(bfqq, in_service_bfqq);
-@@ -2245,21 +2209,12 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 	 * queues. The only thing we need is that the bio/request is not
- 	 * NULL, as we need it to establish whether a cooperator exists.
- 	 */
--check_scheduled:
- 	new_bfqq = bfq_find_close_cooperator(bfqd, bfqq,
- 			bfq_io_struct_pos(io_struct, request));
- 
- 	BUG_ON(new_bfqq && bfqq->entity.parent != new_bfqq->entity.parent);
- 
--	if (new_bfqq && wr_from_too_long(new_bfqq) &&
--	    likely(new_bfqq != &bfqd->oom_bfqq) &&
--	    bfq_may_be_close_cooperator(bfqq, new_bfqq))
--		bfq_log_bfqq(bfqd, bfqq,
--			     "would have merged with bfq%d, but wr",
--			     new_bfqq->pid);
--
--	if (new_bfqq && !wr_from_too_long(new_bfqq) &&
--	    likely(new_bfqq != &bfqd->oom_bfqq) &&
-+	if (new_bfqq && likely(new_bfqq != &bfqd->oom_bfqq) &&
- 	    bfq_may_be_close_cooperator(bfqq, new_bfqq))
- 		return bfq_setup_merge(bfqq, new_bfqq);
- 
-diff --git a/block/bfq-sq-iosched.c b/block/bfq-sq-iosched.c
-index cd00a41ca35d..d8a358e5e284 100644
---- a/block/bfq-sq-iosched.c
-+++ b/block/bfq-sq-iosched.c
-@@ -2019,20 +2019,6 @@ static bool bfq_may_be_close_cooperator(struct bfq_queue *bfqq,
- 	return true;
- }
- 
--/*
-- * If this function returns true, then bfqq cannot be merged. The idea
-- * is that true cooperation happens very early after processes start
-- * to do I/O. Usually, late cooperations are just accidental false
-- * positives. In case bfqq is weight-raised, such false positives
-- * would evidently degrade latency guarantees for bfqq.
-- */
--static bool wr_from_too_long(struct bfq_queue *bfqq)
--{
--	return bfqq->wr_coeff > 1 &&
--		time_is_before_jiffies(bfqq->last_wr_start_finish +
--				       msecs_to_jiffies(100));
--}
--
- /*
-  * Attempt to schedule a merge of bfqq with the currently in-service
-  * queue or with a close queue among the scheduled queues.  Return
-@@ -2046,11 +2032,6 @@ static bool wr_from_too_long(struct bfq_queue *bfqq)
-  * to maintain. Besides, in such a critical condition as an out of memory,
-  * the benefits of queue merging may be little relevant, or even negligible.
-  *
-- * Weight-raised queues can be merged only if their weight-raising
-- * period has just started. In fact cooperating processes are usually
-- * started together. Thus, with this filter we avoid false positives
-- * that would jeopardize low-latency guarantees.
-- *
-  * WARNING: queue merging may impair fairness among non-weight raised
-  * queues, for at least two reasons: 1) the original weight of a
-  * merged queue may change during the merged state, 2) even being the
-@@ -2084,15 +2065,7 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 	if (bfqq->new_bfqq)
- 		return bfqq->new_bfqq;
- 
--	if (io_struct && wr_from_too_long(bfqq) &&
--	    likely(bfqq != &bfqd->oom_bfqq))
--		bfq_log_bfqq(bfqd, bfqq,
--			     "would have looked for coop, but bfq%d wr",
--			bfqq->pid);
--
--	if (!io_struct ||
--	    wr_from_too_long(bfqq) ||
--	    unlikely(bfqq == &bfqd->oom_bfqq))
-+	if (!io_struct || unlikely(bfqq == &bfqd->oom_bfqq))
- 		return NULL;
- 
- 	/* If there is only one backlogged queue, don't search. */
-@@ -2102,17 +2075,8 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 	in_service_bfqq = bfqd->in_service_queue;
- 
- 	if (in_service_bfqq && in_service_bfqq != bfqq &&
--	    bfqd->in_service_bic && wr_from_too_long(in_service_bfqq)
--	    && likely(in_service_bfqq == &bfqd->oom_bfqq))
--		bfq_log_bfqq(bfqd, bfqq,
--		"would have tried merge with in-service-queue, but wr");
--
--	if (!in_service_bfqq || in_service_bfqq == bfqq ||
--	    !bfqd->in_service_bic || wr_from_too_long(in_service_bfqq) ||
--	    unlikely(in_service_bfqq == &bfqd->oom_bfqq))
--		goto check_scheduled;
--
--	if (bfq_rq_close_to_sector(io_struct, request, bfqd->last_position) &&
-+	    likely(in_service_bfqq != &bfqd->oom_bfqq) &&
-+	    bfq_rq_close_to_sector(io_struct, request, bfqd->last_position) &&
- 	    bfqq->entity.parent == in_service_bfqq->entity.parent &&
- 	    bfq_may_be_close_cooperator(bfqq, in_service_bfqq)) {
- 		new_bfqq = bfq_setup_merge(bfqq, in_service_bfqq);
-@@ -2124,21 +2088,12 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 	 * queues. The only thing we need is that the bio/request is not
- 	 * NULL, as we need it to establish whether a cooperator exists.
- 	 */
--check_scheduled:
- 	new_bfqq = bfq_find_close_cooperator(bfqd, bfqq,
- 			bfq_io_struct_pos(io_struct, request));
- 
- 	BUG_ON(new_bfqq && bfqq->entity.parent != new_bfqq->entity.parent);
- 
--	if (new_bfqq && wr_from_too_long(new_bfqq) &&
--	    likely(new_bfqq != &bfqd->oom_bfqq) &&
--	    bfq_may_be_close_cooperator(bfqq, new_bfqq))
--		bfq_log_bfqq(bfqd, bfqq,
--			     "would have merged with bfq%d, but wr",
--			     new_bfqq->pid);
--
--	if (new_bfqq && !wr_from_too_long(new_bfqq) &&
--	    likely(new_bfqq != &bfqd->oom_bfqq) &&
-+	if (new_bfqq && likely(new_bfqq != &bfqd->oom_bfqq) &&
- 	    bfq_may_be_close_cooperator(bfqq, new_bfqq))
- 		return bfq_setup_merge(bfqq, new_bfqq);
- 
-
-From b82eb91d87f172aba7eb5eb98e8d5e2a621adf51 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Thu, 30 Nov 2017 17:48:28 +0100
-Subject: [PATCH 08/23] block, bfq-sq, bfq-mq: increase threshold to deem I/O
- as random
-
-If two processes do I/O close to each other, i.e., are cooperating
-processes in BFQ (and CFQ'S) nomenclature, then BFQ merges their
-associated bfq_queues, so as to get sequential I/O from the union of
-the I/O requests of the processes, and thus reach a higher
-throughput. A merged queue is then split if its I/O stops being
-sequential. In this respect, BFQ deems the I/O of a bfq_queue as
-(mostly) sequential only if less than 4 I/O requests are random, out
-of the last 32 requests inserted into the queue.
-
-Unfortunately, extensive testing (with the interleaved_io benchmark of
-the S suite [1], and with real applications spawning cooperating
-processes) has clearly shown that, with such a low threshold, only a
-rather low I/O throughput may be reached when several cooperating
-processes do I/O. In particular, the outcome of each test run was
-bimodal: if queue merging occurred and was stable during the test,
-then the throughput was close to the peak rate of the storage device,
-otherwise the throughput was arbitrarily low (usually around 1/10 of
-the peak rate with a rotational device). The probability to get the
-unlucky outcomes grew with the number of cooperating processes: it was
-already significant with 5 processes, and close to one with 7 or more
-processes.
-
-The cause of the low throughput in the unlucky runs was that the
-merged queues containing the I/O of these cooperating processes were
-soon split, because they contained more random I/O requests than those
-tolerated by the 4/32 threshold, but
-- that I/O would have however allowed the storage device to reach
-  peak throughput or almost peak throughput;
-- in contrast, the I/O of these processes, if served individually
-  (from separate queues) yielded a rather low throughput.
-
-So we repeated our tests with increasing values of the threshold,
-until we found the minimum value (19) for which we obtained maximum
-throughput, reliably, with at least up to 9 cooperating
-processes. Then we checked that the use of that higher threshold value
-did not cause any regression for any other benchmark in the suite [1].
-This commit raises the threshold to such a higher value.
-
-[1] https://github.com/Algodev-github/S
-
-Signed-off-by: Angelo Ruocco <angeloruocco90@gmail.com>
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-mq-iosched.c | 2 +-
- block/bfq-sq-iosched.c | 2 +-
- 2 files changed, 2 insertions(+), 2 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index f5db8613a70f..cb5f49ddecb6 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -145,7 +145,7 @@ static struct kmem_cache *bfq_pool;
- #define BFQQ_SEEK_THR		(sector_t)(8 * 100)
- #define BFQQ_SECT_THR_NONROT	(sector_t)(2 * 32)
- #define BFQQ_CLOSE_THR		(sector_t)(8 * 1024)
--#define BFQQ_SEEKY(bfqq)	(hweight32(bfqq->seek_history) > 32/8)
-+#define BFQQ_SEEKY(bfqq)	(hweight32(bfqq->seek_history) > 19)
- 
- /* Min number of samples required to perform peak-rate update */
- #define BFQ_RATE_MIN_SAMPLES	32
-diff --git a/block/bfq-sq-iosched.c b/block/bfq-sq-iosched.c
-index d8a358e5e284..e1c6dc651be1 100644
---- a/block/bfq-sq-iosched.c
-+++ b/block/bfq-sq-iosched.c
-@@ -139,7 +139,7 @@ static struct kmem_cache *bfq_pool;
- #define BFQQ_SEEK_THR		(sector_t)(8 * 100)
- #define BFQQ_SECT_THR_NONROT	(sector_t)(2 * 32)
- #define BFQQ_CLOSE_THR		(sector_t)(8 * 1024)
--#define BFQQ_SEEKY(bfqq)	(hweight32(bfqq->seek_history) > 32/8)
-+#define BFQQ_SEEKY(bfqq)	(hweight32(bfqq->seek_history) > 19)
- 
- /* Min number of samples required to perform peak-rate update */
- #define BFQ_RATE_MIN_SAMPLES	32
-
-From b739dda4e4b3a1cbbc905f86f9fbb0860b068ce7 Mon Sep 17 00:00:00 2001
-From: Chiara Bruschi <bruschi.chiara@outlook.it>
-Date: Mon, 11 Dec 2017 18:55:26 +0100
-Subject: [PATCH 09/23] block, bfq-sq, bfq-mq: specify usage condition of
- delta_us in bfq_log_bfqq call
-
-Inside the function bfq_completed_request the value of a variable
-called delta_us is computed as current request completion time.
-delta_us is used inside a call to the function bfq_log_bfqq as divisor
-in a division operation to compute a rate value, but no check makes
-sure that delta_us has non-zero value. A divisor with value 0 leads
-to a division error that could result in a kernel oops (therefore
-unstable/unreliable system state) and consequently cause kernel panic
-if resources are unavailable after the system fault.
-
-This commit fixes this call to bfq_log_bfqq specifying the condition
-that allows delta_us to be safely used as divisor.
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
-Signed-off-by: Chiara Bruschi <bruschi.chiara@outlook.it>
----
- block/bfq-mq-iosched.c | 5 ++++-
- block/bfq-sq-iosched.c | 5 ++++-
- 2 files changed, 8 insertions(+), 2 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index cb5f49ddecb6..6ce2c0789046 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -4904,9 +4904,12 @@ static void bfq_completed_request(struct bfq_queue *bfqq, struct bfq_data *bfqd)
- 	bfq_log_bfqq(bfqd, bfqq,
- 		"rq_completed: delta %uus/%luus max_size %u rate %llu/%llu",
- 		delta_us, BFQ_MIN_TT/NSEC_PER_USEC, bfqd->last_rq_max_size,
-+		delta_us > 0 ?
- 		(USEC_PER_SEC*
- 		(u64)((bfqd->last_rq_max_size<<BFQ_RATE_SHIFT)/delta_us))
--			>>BFQ_RATE_SHIFT,
-+			>>BFQ_RATE_SHIFT :
-+		(USEC_PER_SEC*
-+		(u64)(bfqd->last_rq_max_size<<BFQ_RATE_SHIFT))>>BFQ_RATE_SHIFT,
- 		(USEC_PER_SEC*(u64)(1UL<<(BFQ_RATE_SHIFT-10)))>>BFQ_RATE_SHIFT);
- 
- 	/*
-diff --git a/block/bfq-sq-iosched.c b/block/bfq-sq-iosched.c
-index e1c6dc651be1..eff4c4edf5a0 100644
---- a/block/bfq-sq-iosched.c
-+++ b/block/bfq-sq-iosched.c
-@@ -4565,9 +4565,12 @@ static void bfq_completed_request(struct request_queue *q, struct request *rq)
- 
- 	bfq_log(bfqd, "rq_completed: delta %uus/%luus max_size %u rate %llu/%llu",
- 		delta_us, BFQ_MIN_TT/NSEC_PER_USEC, bfqd->last_rq_max_size,
-+		delta_us > 0 ?
- 		(USEC_PER_SEC*
- 		(u64)((bfqd->last_rq_max_size<<BFQ_RATE_SHIFT)/delta_us))
--			>>BFQ_RATE_SHIFT,
-+			>>BFQ_RATE_SHIFT :
-+		(USEC_PER_SEC*
-+		(u64)(bfqd->last_rq_max_size<<BFQ_RATE_SHIFT))>>BFQ_RATE_SHIFT,
- 		(USEC_PER_SEC*(u64)(1UL<<(BFQ_RATE_SHIFT-10)))>>BFQ_RATE_SHIFT);
- 
- 	/*
-
-From ae4310c13eca762644734d53074d8456c85e2dec Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Tue, 19 Dec 2017 12:07:12 +0100
-Subject: [PATCH 10/23] block, bfq-mq: limit tags for writes and async I/O
-
-Asynchronous I/O can easily starve synchronous I/O (both sync reads
-and sync writes), by consuming all request tags. Similarly, storms of
-synchronous writes, such as those that sync(2) may trigger, can starve
-synchronous reads. In their turn, these two problems may also cause
-BFQ to loose control on latency for interactive and soft real-time
-applications. For example, on a PLEXTOR PX-256M5S SSD, LibreOffice
-Writer takes 0.6 seconds to start if the device is idle, but it takes
-more than 45 seconds (!) if there are sequential writes in the
-background.
-
-This commit addresses this issue by limiting the maximum percentage of
-tags that asynchronous I/O requests and synchronous write requests can
-consume. In particular, this commit grants a higher threshold to
-synchronous writes, to prevent the latter from being starved by
-asynchronous I/O.
-
-According to the above test, LibreOffice Writer now starts in about
-1.2 seconds on average, regardless of the background workload, and
-apart from some rare outlier. To check this improvement, run, e.g.,
-sudo ./comm_startup_lat.sh bfq-mq 5 5 seq 10 "lowriter --terminate_after_init"
-for the comm_startup_lat benchmark in the S suite [1].
-
-[1] https://github.com/Algodev-github/S
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-mq-iosched.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++++++
- block/bfq-mq.h         | 12 ++++++++
- 2 files changed, 89 insertions(+)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 6ce2c0789046..f384f5566672 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -362,6 +362,82 @@ static struct request *bfq_choose_req(struct bfq_data *bfqd,
- 	}
- }
- 
-+/*
-+ * See the comments on bfq_limit_depth for the purpose of
-+ * the depths set in the function.
-+ */
-+static void bfq_update_depths(struct bfq_data *bfqd, struct sbitmap_queue *bt)
-+{
-+	bfqd->sb_shift = bt->sb.shift;
-+
-+	/*
-+	 * In-word depths if no bfq_queue is being weight-raised:
-+	 * leaving 25% of tags only for sync reads.
-+	 *
-+	 * In next formulas, right-shift the value
-+	 * (1U<<bfqd->sb_shift), instead of computing directly
-+	 * (1U<<(bfqd->sb_shift - something)), to be robust against
-+	 * any possible value of bfqd->sb_shift, without having to
-+	 * limit 'something'.
-+	 */
-+	/* no more than 50% of tags for async I/O */
-+	bfqd->word_depths[0][0] = max((1U<<bfqd->sb_shift)>>1, 1U);
-+	/*
-+	 * no more than 75% of tags for sync writes (25% extra tags
-+	 * w.r.t. async I/O, to prevent async I/O from starving sync
-+	 * writes)
-+	 */
-+	bfqd->word_depths[0][1] = max(((1U<<bfqd->sb_shift) * 3)>>2, 1U);
-+
-+	/*
-+	 * In-word depths in case some bfq_queue is being weight-
-+	 * raised: leaving ~63% of tags for sync reads. This is the
-+	 * highest percentage for which, in our tests, application
-+	 * start-up times didn't suffer from any regression due to tag
-+	 * shortage.
-+	 */
-+	/* no more than ~18% of tags for async I/O */
-+	bfqd->word_depths[1][0] = max(((1U<<bfqd->sb_shift) * 3)>>4, 1U);
-+	/* no more than ~37% of tags for sync writes (~20% extra tags) */
-+	bfqd->word_depths[1][1] = max(((1U<<bfqd->sb_shift) * 6)>>4, 1U);
-+}
-+
-+/*
-+ * Async I/O can easily starve sync I/O (both sync reads and sync
-+ * writes), by consuming all tags. Similarly, storms of sync writes,
-+ * such as those that sync(2) may trigger, can starve sync reads.
-+ * Limit depths of async I/O and sync writes so as to counter both
-+ * problems.
-+ */
-+static void bfq_limit_depth(unsigned int op, struct blk_mq_alloc_data *data)
-+{
-+	struct blk_mq_tags *tags = blk_mq_tags_from_data(data);
-+	struct bfq_data *bfqd = data->q->elevator->elevator_data;
-+	struct sbitmap_queue *bt;
-+
-+	if (op_is_sync(op) && !op_is_write(op))
-+		return;
-+
-+	if (data->flags & BLK_MQ_REQ_RESERVED) {
-+		if (unlikely(!tags->nr_reserved_tags)) {
-+			WARN_ON_ONCE(1);
-+			return;
-+		}
-+		bt = &tags->breserved_tags;
-+	} else
-+		bt = &tags->bitmap_tags;
-+
-+	if (unlikely(bfqd->sb_shift != bt->sb.shift))
-+		bfq_update_depths(bfqd, bt);
-+
-+	data->shallow_depth =
-+		bfqd->word_depths[!!bfqd->wr_busy_queues][op_is_sync(op)];
-+
-+	bfq_log(bfqd, "[%s] wr_busy %d sync %d depth %u",
-+			__func__, bfqd->wr_busy_queues, op_is_sync(op),
-+			data->shallow_depth);
-+}
-+
- static struct bfq_queue *
- bfq_rq_pos_tree_lookup(struct bfq_data *bfqd, struct rb_root *root,
- 		     sector_t sector, struct rb_node **ret_parent,
-@@ -5812,6 +5888,7 @@ static struct elv_fs_entry bfq_attrs[] = {
- 
- static struct elevator_type iosched_bfq_mq = {
- 	.ops.mq = {
-+		.limit_depth		= bfq_limit_depth,
- 		.prepare_request        = bfq_prepare_request,
- 		.finish_request         = bfq_finish_request,
- 		.exit_icq		= bfq_exit_icq,
-diff --git a/block/bfq-mq.h b/block/bfq-mq.h
-index a5947b203ef2..458099ee0308 100644
---- a/block/bfq-mq.h
-+++ b/block/bfq-mq.h
-@@ -619,6 +619,18 @@ struct bfq_data {
- 	struct bfq_queue *bio_bfqq;
- 	/* Extra flag used only for TESTING */
- 	bool bio_bfqq_set;
-+
-+	/*
-+	 * Cached sbitmap shift, used to compute depth limits in
-+	 * bfq_update_depths.
-+	 */
-+	unsigned int sb_shift;
-+
-+	/*
-+	 * Depth limits used in bfq_limit_depth (see comments on the
-+	 * function)
-+	 */
-+	unsigned int word_depths[2][2];
- };
- 
- enum bfqq_state_flags {
-
-From 402e5f6b59662d290ab2b3c10b0016207a63ad21 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Thu, 21 Dec 2017 15:51:39 +0100
-Subject: [PATCH 11/23] bfq-sq, bfq-mq: limit sectors served with interactive
- weight raising
-
-To maximise responsiveness, BFQ raises the weight, and performs device
-idling, for bfq_queues associated with processes deemed as
-interactive. In particular, weight raising has a maximum duration,
-equal to the time needed to start a large application. If a
-weight-raised process goes on doing I/O beyond this maximum duration,
-it loses weight-raising.
-
-This mechanism is evidently vulnerable to the following false
-positives: I/O-bound applications that will go on doing I/O for much
-longer than the duration of weight-raising. These applications have
-basically no benefit from being weight-raised at the beginning of
-their I/O. On the opposite end, while being weight-raised, these
-applications
-a) unjustly steal throughput to applications that may truly need
-low latency;
-b) make BFQ uselessly perform device idling; device idling results
-in loss of device throughput with most flash-based storage, and may
-increase latencies when used purposelessly.
-
-This commit adds a countermeasure to reduce both the above
-problems. To introduce this countermeasure, we provide the following
-extra piece of information (full details in the comments added by this
-commit). During the start-up of the large application used as a
-reference to set the duration of weight-raising, involved processes
-transfer at most ~110K sectors each. Accordingly, a process initially
-deemed as interactive has no right to be weight-raised any longer,
-once transferred 110K sectors or more.
-
-Basing on this consideration, this commit early-ends weight-raising
-for a bfq_queue if the latter happens to have received an amount of
-service at least equal to 110K sectors (actually, a little bit more,
-to keep a safety margin). I/O-bound applications that reach a high
-throughput, such as file copy, get to this threshold much before the
-allowed weight-raising period finishes. Thus this early ending of
-weight-raising reduces the amount of time during which these
-applications cause the problems described above.
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-mq-iosched.c | 84 ++++++++++++++++++++++++++++++++++++++++++++------
- block/bfq-mq.h         |  5 +++
- block/bfq-sched.c      |  3 ++
- block/bfq-sq-iosched.c | 84 ++++++++++++++++++++++++++++++++++++++++++++------
- block/bfq.h            |  5 +++
- 5 files changed, 163 insertions(+), 18 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index f384f5566672..63fdd16dec3c 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -162,15 +162,17 @@ static struct kmem_cache *bfq_pool;
-  * interactive applications automatically, using the following formula:
-  * duration = (R / r) * T, where r is the peak rate of the device, and
-  * R and T are two reference parameters.
-- * In particular, R is the peak rate of the reference device (see below),
-- * and T is a reference time: given the systems that are likely to be
-- * installed on the reference device according to its speed class, T is
-- * about the maximum time needed, under BFQ and while reading two files in
-- * parallel, to load typical large applications on these systems.
-- * In practice, the slower/faster the device at hand is, the more/less it
-- * takes to load applications with respect to the reference device.
-- * Accordingly, the longer/shorter BFQ grants weight raising to interactive
-- * applications.
-+ * In particular, R is the peak rate of the reference device (see
-+ * below), and T is a reference time: given the systems that are
-+ * likely to be installed on the reference device according to its
-+ * speed class, T is about the maximum time needed, under BFQ and
-+ * while reading two files in parallel, to load typical large
-+ * applications on these systems (see the comments on
-+ * max_service_from_wr below, for more details on how T is obtained).
-+ * In practice, the slower/faster the device at hand is, the more/less
-+ * it takes to load applications with respect to the reference device.
-+ * Accordingly, the longer/shorter BFQ grants weight raising to
-+ * interactive applications.
-  *
-  * BFQ uses four different reference pairs (R, T), depending on:
-  * . whether the device is rotational or non-rotational;
-@@ -207,6 +209,60 @@ static int T_slow[2];
- static int T_fast[2];
- static int device_speed_thresh[2];
- 
-+/*
-+ * BFQ uses the above-detailed, time-based weight-raising mechanism to
-+ * privilege interactive tasks. This mechanism is vulnerable to the
-+ * following false positives: I/O-bound applications that will go on
-+ * doing I/O for much longer than the duration of weight
-+ * raising. These applications have basically no benefit from being
-+ * weight-raised at the beginning of their I/O. On the opposite end,
-+ * while being weight-raised, these applications
-+ * a) unjustly steal throughput to applications that may actually need
-+ * low latency;
-+ * b) make BFQ uselessly perform device idling; device idling results
-+ * in loss of device throughput with most flash-based storage, and may
-+ * increase latencies when used purposelessly.
-+ *
-+ * BFQ tries to reduce these problems, by adopting the following
-+ * countermeasure. To introduce this countermeasure, we need first to
-+ * finish explaining how the duration of weight-raising for
-+ * interactive tasks is computed.
-+ *
-+ * For a bfq_queue deemed as interactive, the duration of weight
-+ * raising is dynamically adjusted, as a function of the estimated
-+ * peak rate of the device, so as to be equal to the time needed to
-+ * execute the 'largest' interactive task we benchmarked so far. By
-+ * largest task, we mean the task for which each involved process has
-+ * to do more I/O than for any of the other tasks we benchmarked. This
-+ * reference interactive task is the start-up of LibreOffice Writer,
-+ * and in this task each process/bfq_queue needs to have at most ~110K
-+ * sectors transferred.
-+ *
-+ * This last piece of information enables BFQ to reduce the actual
-+ * duration of weight-raising for at least one class of I/O-bound
-+ * applications: those doing sequential or quasi-sequential I/O. An
-+ * example is file copy. In fact, once started, the main I/O-bound
-+ * processes of these applications usually consume the above 110K
-+ * sectors in much less time than the processes of an application that
-+ * is starting, because these I/O-bound processes will greedily devote
-+ * almost all their CPU cycles only to their target,
-+ * throughput-friendly I/O operations. This is even more true if BFQ
-+ * happens to be underestimating the device peak rate, and thus
-+ * overestimating the duration of weight raising. But, according to
-+ * our measurements, once transferred 110K sectors, these processes
-+ * have no right to be weight-raised any longer.
-+ *
-+ * Basing on the last consideration, BFQ ends weight-raising for a
-+ * bfq_queue if the latter happens to have received an amount of
-+ * service at least equal to the following constant. The constant is
-+ * set to slightly more than 110K, to have a minimum safety margin.
-+ *
-+ * This early ending of weight-raising reduces the amount of time
-+ * during which interactive false positives cause the two problems
-+ * described at the beginning of these comments.
-+ */
-+static const unsigned long max_service_from_wr = 120000;
-+
- #define BFQ_SERVICE_TREE_INIT	((struct bfq_service_tree)		\
- 				{ RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 })
- 
-@@ -1361,6 +1417,7 @@ static void bfq_update_bfqq_wr_on_rq_arrival(struct bfq_data *bfqd,
- 	if (old_wr_coeff == 1 && wr_or_deserves_wr) {
- 		/* start a weight-raising period */
- 		if (interactive) {
-+			bfqq->service_from_wr = 0;
- 			bfqq->wr_coeff = bfqd->bfq_wr_coeff;
- 			bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
- 		} else {
-@@ -3980,6 +4037,15 @@ static void bfq_update_wr_data(struct bfq_data *bfqd, struct bfq_queue *bfqq)
- 					"back to interactive wr");
- 			}
- 		}
-+		if (bfqq->wr_coeff > 1 &&
-+		    bfqq->wr_cur_max_time != bfqd->bfq_wr_rt_max_time &&
-+		    bfqq->service_from_wr > max_service_from_wr) {
-+			/* see comments on max_service_from_wr */
-+			bfq_bfqq_end_wr(bfqq);
-+			bfq_log_bfqq(bfqd, bfqq,
-+				     "[%s] too much service",
-+				     __func__);
-+		}
- 	}
- 	/*
- 	 * To improve latency (for this or other queues), immediately
-diff --git a/block/bfq-mq.h b/block/bfq-mq.h
-index 458099ee0308..9a5ce1168ff5 100644
---- a/block/bfq-mq.h
-+++ b/block/bfq-mq.h
-@@ -331,6 +331,11 @@ struct bfq_queue {
- 	 * last transition from idle to backlogged.
- 	 */
- 	unsigned long service_from_backlogged;
-+	/*
-+	 * Cumulative service received from the @bfq_queue since its
-+	 * last transition to weight-raised state.
-+	 */
-+	unsigned long service_from_wr;
- 	/*
- 	 * Value of wr start time when switching to soft rt
- 	 */
-diff --git a/block/bfq-sched.c b/block/bfq-sched.c
-index 9d261dd428e4..4e6c5232e2fb 100644
---- a/block/bfq-sched.c
-+++ b/block/bfq-sched.c
-@@ -942,6 +942,9 @@ static void bfq_bfqq_served(struct bfq_queue *bfqq, int served)
- 	if (!bfqq->service_from_backlogged)
- 		bfqq->first_IO_time = jiffies;
- 
-+	if (bfqq->wr_coeff > 1)
-+		bfqq->service_from_wr += served;
-+
- 	bfqq->service_from_backlogged += served;
- 	for_each_entity(entity) {
- 		st = bfq_entity_service_tree(entity);
-diff --git a/block/bfq-sq-iosched.c b/block/bfq-sq-iosched.c
-index eff4c4edf5a0..486493aafaf8 100644
---- a/block/bfq-sq-iosched.c
-+++ b/block/bfq-sq-iosched.c
-@@ -156,15 +156,17 @@ static struct kmem_cache *bfq_pool;
-  * interactive applications automatically, using the following formula:
-  * duration = (R / r) * T, where r is the peak rate of the device, and
-  * R and T are two reference parameters.
-- * In particular, R is the peak rate of the reference device (see below),
-- * and T is a reference time: given the systems that are likely to be
-- * installed on the reference device according to its speed class, T is
-- * about the maximum time needed, under BFQ and while reading two files in
-- * parallel, to load typical large applications on these systems.
-- * In practice, the slower/faster the device at hand is, the more/less it
-- * takes to load applications with respect to the reference device.
-- * Accordingly, the longer/shorter BFQ grants weight raising to interactive
-- * applications.
-+ * In particular, R is the peak rate of the reference device (see
-+ * below), and T is a reference time: given the systems that are
-+ * likely to be installed on the reference device according to its
-+ * speed class, T is about the maximum time needed, under BFQ and
-+ * while reading two files in parallel, to load typical large
-+ * applications on these systems (see the comments on
-+ * max_service_from_wr below, for more details on how T is obtained).
-+ * In practice, the slower/faster the device at hand is, the more/less
-+ * it takes to load applications with respect to the reference device.
-+ * Accordingly, the longer/shorter BFQ grants weight raising to
-+ * interactive applications.
-  *
-  * BFQ uses four different reference pairs (R, T), depending on:
-  * . whether the device is rotational or non-rotational;
-@@ -201,6 +203,60 @@ static int T_slow[2];
- static int T_fast[2];
- static int device_speed_thresh[2];
- 
-+/*
-+ * BFQ uses the above-detailed, time-based weight-raising mechanism to
-+ * privilege interactive tasks. This mechanism is vulnerable to the
-+ * following false positives: I/O-bound applications that will go on
-+ * doing I/O for much longer than the duration of weight
-+ * raising. These applications have basically no benefit from being
-+ * weight-raised at the beginning of their I/O. On the opposite end,
-+ * while being weight-raised, these applications
-+ * a) unjustly steal throughput to applications that may actually need
-+ * low latency;
-+ * b) make BFQ uselessly perform device idling; device idling results
-+ * in loss of device throughput with most flash-based storage, and may
-+ * increase latencies when used purposelessly.
-+ *
-+ * BFQ tries to reduce these problems, by adopting the following
-+ * countermeasure. To introduce this countermeasure, we need first to
-+ * finish explaining how the duration of weight-raising for
-+ * interactive tasks is computed.
-+ *
-+ * For a bfq_queue deemed as interactive, the duration of weight
-+ * raising is dynamically adjusted, as a function of the estimated
-+ * peak rate of the device, so as to be equal to the time needed to
-+ * execute the 'largest' interactive task we benchmarked so far. By
-+ * largest task, we mean the task for which each involved process has
-+ * to do more I/O than for any of the other tasks we benchmarked. This
-+ * reference interactive task is the start-up of LibreOffice Writer,
-+ * and in this task each process/bfq_queue needs to have at most ~110K
-+ * sectors transfered.
-+ *
-+ * This last piece of information enables BFQ to reduce the actual
-+ * duration of weight-raising for at least one class of I/O-bound
-+ * applications: those doing sequential or quasi-sequential I/O. An
-+ * example is file copy. In fact, once started, the main I/O-bound
-+ * processes of these applications usually consume the above 110K
-+ * sectors in much less time than the processes of an application that
-+ * is starting, because these I/O-bound processes will greedily devote
-+ * almost all their CPU cycles only to their target,
-+ * throughput-friendly I/O operations. This is even more true if BFQ
-+ * happens to be underestimating the device peak rate, and thus
-+ * overestimating the duration of weight raising. But, according to
-+ * our measurements, once transferred 110K sectors, these processes
-+ * have no right to be weight-raised any longer.
-+ *
-+ * Basing on the last consideration, BFQ ends weight-raising for a
-+ * bfq_queue if the latter happens to have received an amount of
-+ * service at least equal to the following constant. The constant is
-+ * set to slightly more than 110K, to have a minimum safety margin.
-+ *
-+ * This early ending of weight-raising reduces the amount of time
-+ * during which interactive false positives cause the two problems
-+ * described at the beginning of these comments.
-+ */
-+static const unsigned long max_service_from_wr = 120000;
-+
- #define BFQ_SERVICE_TREE_INIT	((struct bfq_service_tree)		\
- 				{ RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 })
- 
-@@ -1246,6 +1302,7 @@ static void bfq_update_bfqq_wr_on_rq_arrival(struct bfq_data *bfqd,
- 	if (old_wr_coeff == 1 && wr_or_deserves_wr) {
- 		/* start a weight-raising period */
- 		if (interactive) {
-+			bfqq->service_from_wr = 0;
- 			bfqq->wr_coeff = bfqd->bfq_wr_coeff;
- 			bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
- 		} else {
-@@ -3794,6 +3851,15 @@ static void bfq_update_wr_data(struct bfq_data *bfqd, struct bfq_queue *bfqq)
- 					"back to interactive wr");
- 			}
- 		}
-+		if (bfqq->wr_coeff > 1 &&
-+		       bfqq->wr_cur_max_time != bfqd->bfq_wr_rt_max_time &&
-+		       bfqq->service_from_wr > max_service_from_wr) {
-+			       /* see comments on max_service_from_wr */
-+			       bfq_bfqq_end_wr(bfqq);
-+			       bfq_log_bfqq(bfqd, bfqq,
-+					       "[%s] too much service",
-+					       __func__);
-+	       }
- 	}
- 	/*
- 	 * To improve latency (for this or other queues), immediately
-diff --git a/block/bfq.h b/block/bfq.h
-index 59539adc00a5..0cd7a3f251a7 100644
---- a/block/bfq.h
-+++ b/block/bfq.h
-@@ -323,6 +323,11 @@ struct bfq_queue {
- 	 * last transition from idle to backlogged.
- 	 */
- 	unsigned long service_from_backlogged;
-+	/*
-+	 * Cumulative service received from the @bfq_queue since its
-+	 * last transition to weight-raised state.
-+	 */
-+	unsigned long service_from_wr;
- 	/*
- 	 * Value of wr start time when switching to soft rt
- 	 */
-
-From 59efebb94b2f9bac653faf62dadb45b83bd27fa7 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Thu, 4 Jan 2018 16:29:58 +0100
-Subject: [PATCH 12/23] bfq-sq, bfq-mq: put async queues for root bfq groups
- too
-MIME-Version: 1.0
-Content-Type: text/plain; charset=UTF-8
-Content-Transfer-Encoding: 8bit
-
-For each pair [device for which bfq is selected as I/O scheduler,
-group in blkio/io], bfq maintains a corresponding bfq group. Each such
-bfq group contains a set of async queues, with each async queue
-created on demand, i.e., when some I/O request arrives for it.  On
-creation, an async queue gets an extra reference, to make sure that
-the queue is not freed as long as its bfq group exists.  Accordingly,
-to allow the queue to be freed after the group exited, this extra
-reference must released on group exit.
-
-The above holds also for a bfq root group, i.e., for the bfq group
-corresponding to the root blkio/io root for a given device. Yet, by
-mistake, the references to the existing async queues of a root group
-are not released when the latter exits. This causes a memory leak when
-the instance of bfq for a given device exits. In a similar vein,
-bfqg_stats_xfer_dead is not executed for a root group.
-
-This commit fixes bfq_pd_offline so that the latter executes the above
-missing operations for a root group too.
-
-Reported-by: Holger Hoffstätte <holger@applied-asynchrony.com>
-Reported-by: Guoqing Jiang <gqjiang@suse.com>
-Signed-off-by: Davide Ferrari <davideferrari8@gmail.com>
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-cgroup-included.c | 8 +++++---
- 1 file changed, 5 insertions(+), 3 deletions(-)
-
-diff --git a/block/bfq-cgroup-included.c b/block/bfq-cgroup-included.c
-index 562b0ce581a7..45fefb2e2d57 100644
---- a/block/bfq-cgroup-included.c
-+++ b/block/bfq-cgroup-included.c
-@@ -885,13 +885,13 @@ static void bfq_pd_offline(struct blkg_policy_data *pd)
- 
- 	entity = bfqg->my_entity;
- 
--	if (!entity) /* root group */
--		return;
--
- #ifdef BFQ_MQ
- 	spin_lock_irqsave(&bfqd->lock, flags);
- #endif
- 
-+	if (!entity) /* root group */
-+		goto put_async_queues;
-+
- 	/*
- 	 * Empty all service_trees belonging to this group before
- 	 * deactivating the group itself.
-@@ -926,6 +926,8 @@ static void bfq_pd_offline(struct blkg_policy_data *pd)
- 	BUG_ON(bfqg->sched_data.in_service_entity);
- 
- 	__bfq_deactivate_entity(entity, false);
-+
-+put_async_queues:
- 	bfq_put_async_queues(bfqd, bfqg);
- 
- #ifdef BFQ_MQ
-
-From 2dfbaaaf95054e2da3ededc0deb1ba5a4f589e53 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Mon, 8 Jan 2018 19:38:45 +0100
-Subject: [PATCH 13/23] bfq-sq, bfq-mq: release oom-queue ref to root group on
- exit
-
-On scheduler init, a reference to the root group, and a reference to
-its corresponding blkg are taken for the oom queue. Yet these
-references are not released on scheduler exit, which prevents these
-objects from be freed. This commit adds the missing reference
-releases.
-
-Reported-by: Davide Ferrari <davideferrari8@gmail.com>
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-mq-iosched.c | 3 +++
- block/bfq-sq-iosched.c | 3 +++
- 2 files changed, 6 insertions(+)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 63fdd16dec3c..b82c52fabf91 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -5507,6 +5507,9 @@ static void bfq_exit_queue(struct elevator_queue *e)
- 
- 	BUG_ON(hrtimer_active(&bfqd->idle_slice_timer));
- 
-+	/* release oom-queue reference to root group */
-+	bfqg_and_blkg_put(bfqd->root_group);
-+
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	blkcg_deactivate_policy(bfqd->queue, &blkcg_policy_bfq);
- #else
-diff --git a/block/bfq-sq-iosched.c b/block/bfq-sq-iosched.c
-index 486493aafaf8..851af055664d 100644
---- a/block/bfq-sq-iosched.c
-+++ b/block/bfq-sq-iosched.c
-@@ -5052,6 +5052,9 @@ static void bfq_exit_queue(struct elevator_queue *e)
- 
- 	BUG_ON(hrtimer_active(&bfqd->idle_slice_timer));
- 
-+	/* release oom-queue reference to root group */
-+	bfqg_put(bfqd->root_group);
-+
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	blkcg_deactivate_policy(q, &blkcg_policy_bfq);
- #else
-
-From 13efe00c8292d78d223e1090a7f36426e360eb38 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Mon, 8 Jan 2018 19:40:38 +0100
-Subject: [PATCH 14/23] block, bfq-sq, bfq-mq: trace get and put of bfq groups
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-cgroup-included.c | 15 +++++++++++++++
- block/bfq-mq-iosched.c      |  3 ++-
- 2 files changed, 17 insertions(+), 1 deletion(-)
-
-diff --git a/block/bfq-cgroup-included.c b/block/bfq-cgroup-included.c
-index 45fefb2e2d57..f94743fb2e7d 100644
---- a/block/bfq-cgroup-included.c
-+++ b/block/bfq-cgroup-included.c
-@@ -267,6 +267,8 @@ static struct bfq_group *bfqq_group(struct bfq_queue *bfqq)
- 
- static void bfqg_get(struct bfq_group *bfqg)
- {
-+	trace_printk("bfqg %p\n", bfqg);
-+
- #ifdef BFQ_MQ
- 	bfqg->ref++;
- #else
-@@ -280,6 +282,9 @@ static void bfqg_put(struct bfq_group *bfqg)
- 	bfqg->ref--;
- 
- 	BUG_ON(bfqg->ref < 0);
-+	trace_printk("putting bfqg %p %s\n", bfqg,
-+		     bfqg->ref == 0 ? "and freeing it" : "");
-+
- 	if (bfqg->ref == 0)
- 		kfree(bfqg);
- #else
-@@ -293,6 +298,7 @@ static void bfqg_and_blkg_get(struct bfq_group *bfqg)
- 	/* see comments in bfq_bic_update_cgroup for why refcounting bfqg */
- 	bfqg_get(bfqg);
- 
-+	trace_printk("getting blkg for bfqg %p\n", bfqg);
- 	blkg_get(bfqg_to_blkg(bfqg));
- }
- 
-@@ -300,6 +306,7 @@ static void bfqg_and_blkg_put(struct bfq_group *bfqg)
- {
- 	bfqg_put(bfqg);
- 
-+	trace_printk("putting blkg for bfqg %p\n", bfqg);
- 	blkg_put(bfqg_to_blkg(bfqg));
- }
- #endif
-@@ -382,6 +389,8 @@ static void bfq_init_entity(struct bfq_entity *entity,
- 		 * Make sure that bfqg and its associated blkg do not
- 		 * disappear before entity.
- 		 */
-+		bfq_log_bfqq(bfqq->bfqd, bfqq, "[%s] getting bfqg %p and blkg\n", __func__, bfqg);
-+
- 		bfqg_and_blkg_get(bfqg);
- #else
- 		bfqg_get(bfqg);
-@@ -475,6 +484,7 @@ static struct blkg_policy_data *bfq_pd_alloc(gfp_t gfp, int node)
- 		kfree(bfqg);
- 		return NULL;
- 	}
-+	trace_printk("bfqg %p\n", bfqg);
- 
- #ifdef BFQ_MQ
- 	/* see comments in bfq_bic_update_cgroup for why refcounting */
-@@ -513,6 +523,7 @@ static void bfq_pd_init(struct blkg_policy_data *pd)
- static void bfq_pd_free(struct blkg_policy_data *pd)
- {
- 	struct bfq_group *bfqg = pd_to_bfqg(pd);
-+	trace_printk("bfqg %p\n", bfqg);
- 
- 	bfqg_stats_exit(&bfqg->stats);
- #ifdef BFQ_MQ
-@@ -650,6 +661,8 @@ static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 		bfq_put_idle_entity(bfq_entity_service_tree(entity), entity);
- 	}
- #ifdef BFQ_MQ
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "[%s] putting blkg and bfqg %p\n", __func__, bfqg);
-+
- 	bfqg_and_blkg_put(bfqq_group(bfqq));
- #else
- 	bfqg_put(bfqq_group(bfqq));
-@@ -658,6 +671,8 @@ static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 	entity->parent = bfqg->my_entity;
- 	entity->sched_data = &bfqg->sched_data;
- #ifdef BFQ_MQ
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "[%s] getting blkg and bfqg %p\n", __func__, bfqg);
-+
- 	/* pin down bfqg and its associated blkg  */
- 	bfqg_and_blkg_get(bfqg);
- #else
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index b82c52fabf91..d5b7a6b985d7 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -4385,10 +4385,11 @@ static void bfq_put_queue(struct bfq_queue *bfqq)
- 	if (bfqq->bfqd)
- 		bfq_log_bfqq(bfqq->bfqd, bfqq, "put_queue: %p freed", bfqq);
- 
--	kmem_cache_free(bfq_pool, bfqq);
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "[%s] putting blkg and bfqg %p\n", __func__, bfqg);
- 	bfqg_and_blkg_put(bfqg);
- #endif
-+	kmem_cache_free(bfq_pool, bfqq);
- }
- 
- static void bfq_put_cooperator(struct bfq_queue *bfqq)
-
-From 816b77fba966171974eb5ee25d81bc4e19eaf1b4 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Wed, 10 Jan 2018 09:08:22 +0100
-Subject: [PATCH 15/23] bfq-sq, bfq-mq: compile group put for oom queue only if
- BFQ_GROUP_IOSCHED is set
-
-Commit ("bfq-sq, bfq-mq: release oom-queue ref to root group on exit")
-added a missing put of the root bfq group for the oom queue. That put
-has to be, and can be, performed only if CONFIG_BFQ_GROUP_IOSCHED is
-defined: the function doing the put is even not defined at all if
-CONFIG_BFQ_GROUP_IOSCHED is not defined. But that commit makes that
-put be invoked regardless of whether CONFIG_BFQ_GROUP_IOSCHED is
-defined. This commit fixes this mistake, by making that invocation be
-compiled only if CONFIG_BFQ_GROUP_IOSCHED is actually defined.
-
-Fixes ("block, bfq: release oom-queue ref to root group on exit")
-Reported-by: Jan Alexander Steffens <jan.steffens@gmail.com>
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-mq-iosched.c | 2 +-
- block/bfq-sq-iosched.c | 2 +-
- 2 files changed, 2 insertions(+), 2 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index d5b7a6b985d7..2581fe0f6f2f 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -5508,10 +5508,10 @@ static void bfq_exit_queue(struct elevator_queue *e)
- 
- 	BUG_ON(hrtimer_active(&bfqd->idle_slice_timer));
- 
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	/* release oom-queue reference to root group */
- 	bfqg_and_blkg_put(bfqd->root_group);
- 
--#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	blkcg_deactivate_policy(bfqd->queue, &blkcg_policy_bfq);
- #else
- 	spin_lock_irq(&bfqd->lock);
-diff --git a/block/bfq-sq-iosched.c b/block/bfq-sq-iosched.c
-index 851af055664d..c4df156b1fb4 100644
---- a/block/bfq-sq-iosched.c
-+++ b/block/bfq-sq-iosched.c
-@@ -5052,10 +5052,10 @@ static void bfq_exit_queue(struct elevator_queue *e)
- 
- 	BUG_ON(hrtimer_active(&bfqd->idle_slice_timer));
- 
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	/* release oom-queue reference to root group */
- 	bfqg_put(bfqd->root_group);
- 
--#ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	blkcg_deactivate_policy(q, &blkcg_policy_bfq);
- #else
- 	bfq_put_async_queues(bfqd, bfqd->root_group);
-
-From 643a89c659172b2c9ae16adfe03af4e3e88e1326 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Sat, 13 Jan 2018 18:48:41 +0100
-Subject: [PATCH 16/23] block, bfq-sq, bfq-mq: remove trace_printks
-
-Commit ("block, bfq-sq, bfq-mq: trace get and put of bfq groups")
-unwisely added some invocations of the function trace_printk, which
-is inappropriate in production kernels. This commit removes those
-invocations.
-
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-cgroup-included.c | 10 ----------
- 1 file changed, 10 deletions(-)
-
-diff --git a/block/bfq-cgroup-included.c b/block/bfq-cgroup-included.c
-index f94743fb2e7d..a4f8a03edfc9 100644
---- a/block/bfq-cgroup-included.c
-+++ b/block/bfq-cgroup-included.c
-@@ -267,8 +267,6 @@ static struct bfq_group *bfqq_group(struct bfq_queue *bfqq)
- 
- static void bfqg_get(struct bfq_group *bfqg)
- {
--	trace_printk("bfqg %p\n", bfqg);
--
- #ifdef BFQ_MQ
- 	bfqg->ref++;
- #else
-@@ -282,9 +280,6 @@ static void bfqg_put(struct bfq_group *bfqg)
- 	bfqg->ref--;
- 
- 	BUG_ON(bfqg->ref < 0);
--	trace_printk("putting bfqg %p %s\n", bfqg,
--		     bfqg->ref == 0 ? "and freeing it" : "");
--
- 	if (bfqg->ref == 0)
- 		kfree(bfqg);
- #else
-@@ -298,7 +293,6 @@ static void bfqg_and_blkg_get(struct bfq_group *bfqg)
- 	/* see comments in bfq_bic_update_cgroup for why refcounting bfqg */
- 	bfqg_get(bfqg);
- 
--	trace_printk("getting blkg for bfqg %p\n", bfqg);
- 	blkg_get(bfqg_to_blkg(bfqg));
- }
- 
-@@ -306,7 +300,6 @@ static void bfqg_and_blkg_put(struct bfq_group *bfqg)
- {
- 	bfqg_put(bfqg);
- 
--	trace_printk("putting blkg for bfqg %p\n", bfqg);
- 	blkg_put(bfqg_to_blkg(bfqg));
- }
- #endif
-@@ -484,8 +477,6 @@ static struct blkg_policy_data *bfq_pd_alloc(gfp_t gfp, int node)
- 		kfree(bfqg);
- 		return NULL;
- 	}
--	trace_printk("bfqg %p\n", bfqg);
--
- #ifdef BFQ_MQ
- 	/* see comments in bfq_bic_update_cgroup for why refcounting */
- 	bfqg_get(bfqg);
-@@ -523,7 +514,6 @@ static void bfq_pd_init(struct blkg_policy_data *pd)
- static void bfq_pd_free(struct blkg_policy_data *pd)
- {
- 	struct bfq_group *bfqg = pd_to_bfqg(pd);
--	trace_printk("bfqg %p\n", bfqg);
- 
- 	bfqg_stats_exit(&bfqg->stats);
- #ifdef BFQ_MQ
-
-From ce050275e24fecec800f346c09d9494563e9fc8a Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Mon, 15 Jan 2018 15:07:05 +0100
-Subject: [PATCH 17/23] block, bfq-mq: add requeue-request hook
-
-Commit 'a6a252e64914 ("blk-mq-sched: decide how to handle flush rq via
-RQF_FLUSH_SEQ")' makes all non-flush re-prepared requests for a device
-be re-inserted into the active I/O scheduler for that device. As a
-consequence, I/O schedulers may get the same request inserted again,
-even several times, without a finish_request invoked on that request
-before each re-insertion.
-
-This fact is the cause of the failure reported in [1]. For an I/O
-scheduler, every re-insertion of the same re-prepared request is
-equivalent to the insertion of a new request. For schedulers like
-mq-deadline or kyber, this fact causes no harm. In contrast, it
-confuses a stateful scheduler like BFQ, which keeps state for an I/O
-request, until the finish_request hook is invoked on the request. In
-particular, BFQ may get stuck, waiting forever for the number of
-request dispatches, of the same request, to be balanced by an equal
-number of request completions (while there will be one completion for
-that request). In this state, BFQ may refuse to serve I/O requests
-from other bfq_queues. The hang reported in [1] then follows.
-
-However, the above re-prepared requests undergo a requeue, thus the
-requeue_request hook of the active elevator is invoked for these
-requests, if set. This commit then addresses the above issue by
-properly implementing the hook requeue_request in BFQ.
-
-[1] https://marc.info/?l=linux-block&m=151211117608676
-
-Reported-by: Ivan Kozik <ivan@ludios.org>
-Reported-by: Alban Browaeys <alban.browaeys@gmail.com>
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
-Signed-off-by: Serena Ziviani <ziviani.serena@gmail.com>
----
- block/bfq-mq-iosched.c | 90 ++++++++++++++++++++++++++++++++++++++++----------
- 1 file changed, 73 insertions(+), 17 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 2581fe0f6f2f..bb7ccc2f1165 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -4162,9 +4162,9 @@ static struct request *__bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
- 			 * TESTING: reset DISP_LIST flag, because: 1)
- 			 * this rq this request has passed through
- 			 * bfq_prepare_request, 2) then it will have
--			 * bfq_finish_request invoked on it, and 3) in
--			 * bfq_finish_request we use this flag to check
--			 * that bfq_finish_request is not invoked on
-+			 * bfq_finish_requeue_request invoked on it, and 3) in
-+			 * bfq_finish_requeue_request we use this flag to check
-+			 * that bfq_finish_requeue_request is not invoked on
- 			 * requests for which bfq_prepare_request has
- 			 * been invoked.
- 			 */
-@@ -4173,8 +4173,8 @@ static struct request *__bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
- 		}
- 
- 		/*
--		 * We exploit the bfq_finish_request hook to decrement
--		 * rq_in_driver, but bfq_finish_request will not be
-+		 * We exploit the bfq_finish_requeue_request hook to decrement
-+		 * rq_in_driver, but bfq_finish_requeue_request will not be
- 		 * invoked on this request. So, to avoid unbalance,
- 		 * just start this request, without incrementing
- 		 * rq_in_driver. As a negative consequence,
-@@ -4183,10 +4183,10 @@ static struct request *__bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
- 		 * bfq_schedule_dispatch to be invoked uselessly.
- 		 *
- 		 * As for implementing an exact solution, the
--		 * bfq_finish_request hook, if defined, is probably
-+		 * bfq_finish_requeue_request hook, if defined, is probably
- 		 * invoked also on this request. So, by exploiting
- 		 * this hook, we could 1) increment rq_in_driver here,
--		 * and 2) decrement it in bfq_finish_request. Such a
-+		 * and 2) decrement it in bfq_finish_requeue_request. Such a
- 		 * solution would let the value of the counter be
- 		 * always accurate, but it would entail using an extra
- 		 * interface function. This cost seems higher than the
-@@ -4878,6 +4878,8 @@ static bool __bfq_insert_request(struct bfq_data *bfqd, struct request *rq)
- 	return idle_timer_disabled;
- }
- 
-+static void bfq_prepare_request(struct request *rq, struct bio *bio);
-+
- static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
- 			       bool at_head)
- {
-@@ -4919,6 +4921,20 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
- 		BUG_ON(!(rq->rq_flags & RQF_GOT));
- 		rq->rq_flags &= ~RQF_GOT;
- 
-+		if (!bfqq) {
-+			/*
-+			 * This should never happen. Most likely rq is
-+			 * a requeued regular request, being
-+			 * re-inserted without being first
-+			 * re-prepared. Do a prepare, to avoid
-+			 * failure.
-+			 */
-+			pr_warn("Regular request associated with no queue");
-+			WARN_ON(1);
-+			bfq_prepare_request(rq, rq->bio);
-+			bfqq = RQ_BFQQ(rq);
-+		}
-+
- #if defined(BFQ_GROUP_IOSCHED_ENABLED) &&  defined(CONFIG_DEBUG_BLK_CGROUP)
- 		idle_timer_disabled = __bfq_insert_request(bfqd, rq);
- 		/*
-@@ -5110,7 +5126,7 @@ static void bfq_completed_request(struct bfq_queue *bfqq, struct bfq_data *bfqd)
- 	}
- }
- 
--static void bfq_finish_request_body(struct bfq_queue *bfqq)
-+static void bfq_finish_requeue_request_body(struct bfq_queue *bfqq)
- {
- 	bfq_log_bfqq(bfqq->bfqd, bfqq,
- 		     "put_request_body: allocated %d", bfqq->allocated);
-@@ -5120,7 +5136,13 @@ static void bfq_finish_request_body(struct bfq_queue *bfqq)
- 	bfq_put_queue(bfqq);
- }
- 
--static void bfq_finish_request(struct request *rq)
-+/*
-+ * Handle either a requeue or a finish for rq. The things to do are
-+ * the same in both cases: all references to rq are to be dropped. In
-+ * particular, rq is considered completed from the point of view of
-+ * the scheduler.
-+ */
-+static void bfq_finish_requeue_request(struct request *rq)
- {
- 	struct bfq_queue *bfqq;
- 	struct bfq_data *bfqd;
-@@ -5128,11 +5150,27 @@ static void bfq_finish_request(struct request *rq)
- 
- 	BUG_ON(!rq);
- 
--	if (!rq->elv.icq)
-+	bfqq = RQ_BFQQ(rq);
-+
-+	/*
-+	 * Requeue and finish hooks are invoked in blk-mq without
-+	 * checking whether the involved request is actually still
-+	 * referenced in the scheduler. To handle this fact, the
-+	 * following two checks make this function exit in case of
-+	 * spurious invocations, for which there is nothing to do.
-+	 *
-+	 * First, check whether rq has nothing to do with an elevator.
-+	 */
-+	if (unlikely(!(rq->rq_flags & RQF_ELVPRIV)))
- 		return;
- 
--	bfqq = RQ_BFQQ(rq);
--	BUG_ON(!bfqq);
-+	/*
-+	 * rq either is not associated with any icq, or is an already
-+	 * requeued request that has not (yet) been re-inserted into
-+	 * a bfq_queue.
-+	 */
-+	if (!rq->elv.icq || !bfqq)
-+		return;
- 
- 	bic = RQ_BIC(rq);
- 	BUG_ON(!bic);
-@@ -5145,7 +5183,6 @@ static void bfq_finish_request(struct request *rq)
- 		BUG();
- 	}
- 	BUG_ON(rq->rq_flags & RQF_QUEUED);
--	BUG_ON(!(rq->rq_flags & RQF_ELVPRIV));
- 
- 	bfq_log_bfqq(bfqd, bfqq,
- 		     "putting rq %p with %u sects left, STARTED %d",
-@@ -5166,13 +5203,14 @@ static void bfq_finish_request(struct request *rq)
- 		spin_lock_irqsave(&bfqd->lock, flags);
- 
- 		bfq_completed_request(bfqq, bfqd);
--		bfq_finish_request_body(bfqq);
-+		bfq_finish_requeue_request_body(bfqq);
- 
- 		spin_unlock_irqrestore(&bfqd->lock, flags);
- 	} else {
- 		/*
- 		 * Request rq may be still/already in the scheduler,
--		 * in which case we need to remove it. And we cannot
-+		 * in which case we need to remove it (this should
-+		 * never happen in case of requeue). And we cannot
- 		 * defer such a check and removal, to avoid
- 		 * inconsistencies in the time interval from the end
- 		 * of this function to the start of the deferred work.
-@@ -5189,9 +5227,26 @@ static void bfq_finish_request(struct request *rq)
- 			bfqg_stats_update_io_remove(bfqq_group(bfqq),
- 						    rq->cmd_flags);
- 		}
--		bfq_finish_request_body(bfqq);
-+		bfq_finish_requeue_request_body(bfqq);
- 	}
- 
-+	/*
-+	 * Reset private fields. In case of a requeue, this allows
-+	 * this function to correctly do nothing if it is spuriously
-+	 * invoked again on this same request (see the check at the
-+	 * beginning of the function). Probably, a better general
-+	 * design would be to prevent blk-mq from invoking the requeue
-+	 * or finish hooks of an elevator, for a request that is not
-+	 * referred by that elevator.
-+	 *
-+	 * Resetting the following fields would break the
-+	 * request-insertion logic if rq is re-inserted into a bfq
-+	 * internal queue, without a re-preparation. Here we assume
-+	 * that re-insertions of requeued requests, without
-+	 * re-preparation, can happen only for pass_through or at_head
-+	 * requests (which are not re-inserted into bfq internal
-+	 * queues).
-+	 */
- 	rq->elv.priv[0] = NULL;
- 	rq->elv.priv[1] = NULL;
- }
-@@ -5960,7 +6015,8 @@ static struct elevator_type iosched_bfq_mq = {
- 	.ops.mq = {
- 		.limit_depth		= bfq_limit_depth,
- 		.prepare_request        = bfq_prepare_request,
--		.finish_request         = bfq_finish_request,
-+		.requeue_request	= bfq_finish_requeue_request,
-+		.finish_request         = bfq_finish_requeue_request,
- 		.exit_icq		= bfq_exit_icq,
- 		.insert_requests	= bfq_insert_requests,
- 		.dispatch_request	= bfq_dispatch_request,
-
-From 3e4f292191cc62b3844316b9741534c3f1b36f0a Mon Sep 17 00:00:00 2001
-From: Davide Paganelli <paga.david@gmail.com>
-Date: Thu, 8 Feb 2018 12:19:24 +0100
-Subject: [PATCH 18/23] block, bfq-mq, bfq-sq: make log functions print names
- of calling functions
-
-Add the macro __func__ as a parameter to the invocations of the functions
-pr_crit, blk_add_trace_msg and blk_add_cgroup_trace_msg in bfq_log*
-functions, in order to include automatically in the log messages
-the names of the functions that call the log functions.
-The programmer can then avoid doing it.
-
-Signed-off-by: Davide Paganelli <paga.david@gmail.com>
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-cgroup-included.c |   9 +--
- block/bfq-mq-iosched.c      | 167 ++++++++++++++++++++++----------------------
- block/bfq-mq.h              |  33 ++++-----
- block/bfq-sched.c           |  54 +++++++-------
- block/bfq-sq-iosched.c      | 134 +++++++++++++++++------------------
- block/bfq.h                 |  33 ++++-----
- 6 files changed, 214 insertions(+), 216 deletions(-)
-
-diff --git a/block/bfq-cgroup-included.c b/block/bfq-cgroup-included.c
-index a4f8a03edfc9..613f154e9da5 100644
---- a/block/bfq-cgroup-included.c
-+++ b/block/bfq-cgroup-included.c
-@@ -382,7 +382,8 @@ static void bfq_init_entity(struct bfq_entity *entity,
- 		 * Make sure that bfqg and its associated blkg do not
- 		 * disappear before entity.
- 		 */
--		bfq_log_bfqq(bfqq->bfqd, bfqq, "[%s] getting bfqg %p and blkg\n", __func__, bfqg);
-+		bfq_log_bfqq(bfqq->bfqd, bfqq, "getting bfqg %p and blkg\n",
-+		bfqg);
- 
- 		bfqg_and_blkg_get(bfqg);
- #else
-@@ -651,7 +652,7 @@ static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 		bfq_put_idle_entity(bfq_entity_service_tree(entity), entity);
- 	}
- #ifdef BFQ_MQ
--	bfq_log_bfqq(bfqq->bfqd, bfqq, "[%s] putting blkg and bfqg %p\n", __func__, bfqg);
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "putting blkg and bfqg %p\n", bfqg);
- 
- 	bfqg_and_blkg_put(bfqq_group(bfqq));
- #else
-@@ -661,7 +662,7 @@ static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 	entity->parent = bfqg->my_entity;
- 	entity->sched_data = &bfqg->sched_data;
- #ifdef BFQ_MQ
--	bfq_log_bfqq(bfqq->bfqd, bfqq, "[%s] getting blkg and bfqg %p\n", __func__, bfqg);
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "getting blkg and bfqg %p\n", bfqg);
- 
- 	/* pin down bfqg and its associated blkg  */
- 	bfqg_and_blkg_get(bfqg);
-@@ -721,7 +722,7 @@ static struct bfq_group *__bfq_bic_change_cgroup(struct bfq_data *bfqd,
- 		if (entity->sched_data != &bfqg->sched_data) {
- 			bic_set_bfqq(bic, NULL, 0);
- 			bfq_log_bfqq(bfqd, async_bfqq,
--				     "bic_change_group: %p %d",
-+				     "%p %d",
- 				     async_bfqq,
- 				     async_bfqq->ref);
- 			bfq_put_queue(async_bfqq);
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index bb7ccc2f1165..edc93b6af186 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -310,7 +310,7 @@ static struct bfq_io_cq *bfq_bic_lookup(struct bfq_data *bfqd,
- static void bfq_schedule_dispatch(struct bfq_data *bfqd)
- {
- 	if (bfqd->queued != 0) {
--		bfq_log(bfqd, "schedule dispatch");
-+		bfq_log(bfqd, "");
- 		blk_mq_run_hw_queues(bfqd->queue, true);
- 	}
- }
-@@ -489,8 +489,8 @@ static void bfq_limit_depth(unsigned int op, struct blk_mq_alloc_data *data)
- 	data->shallow_depth =
- 		bfqd->word_depths[!!bfqd->wr_busy_queues][op_is_sync(op)];
- 
--	bfq_log(bfqd, "[%s] wr_busy %d sync %d depth %u",
--			__func__, bfqd->wr_busy_queues, op_is_sync(op),
-+	bfq_log(bfqd, "wr_busy %d sync %d depth %u",
-+			bfqd->wr_busy_queues, op_is_sync(op),
- 			data->shallow_depth);
- }
- 
-@@ -528,7 +528,7 @@ bfq_rq_pos_tree_lookup(struct bfq_data *bfqd, struct rb_root *root,
- 	if (rb_link)
- 		*rb_link = p;
- 
--	bfq_log(bfqd, "rq_pos_tree_lookup %llu: returning %d",
-+	bfq_log(bfqd, "%llu: returning %d",
- 		(unsigned long long) sector,
- 		bfqq ? bfqq->pid : 0);
- 
-@@ -749,7 +749,7 @@ static struct request *bfq_check_fifo(struct bfq_queue *bfqq,
- 	if (rq == last || ktime_get_ns() < rq->fifo_time)
- 		return NULL;
- 
--	bfq_log_bfqq(bfqq->bfqd, bfqq, "check_fifo: returned %p", rq);
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "returned %p", rq);
- 	BUG_ON(RB_EMPTY_NODE(&rq->rb_node));
- 	return rq;
- }
-@@ -842,7 +842,7 @@ static void bfq_updated_next_req(struct bfq_data *bfqd,
- 			   bfq_serv_to_charge(next_rq, bfqq));
- 	if (entity->budget != new_budget) {
- 		entity->budget = new_budget;
--		bfq_log_bfqq(bfqd, bfqq, "updated next rq: new budget %lu",
-+		bfq_log_bfqq(bfqd, bfqq, "new budget %lu",
- 					 new_budget);
- 		bfq_requeue_bfqq(bfqd, bfqq, false);
- 	}
-@@ -915,8 +915,7 @@ bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_data *bfqd,
- 	BUG_ON(time_is_after_jiffies(bfqq->last_wr_start_finish));
- 
- 	bfq_log_bfqq(bfqq->bfqd, bfqq,
--		     "[%s] bic %p wr_coeff %d start_finish %lu max_time %lu",
--		     __func__,
-+		     "bic %p wr_coeff %d start_finish %lu max_time %lu",
- 		     bic, bfqq->wr_coeff, bfqq->last_wr_start_finish,
- 		     bfqq->wr_cur_max_time);
- 
-@@ -929,11 +928,11 @@ bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_data *bfqd,
- 					     bfq_wr_duration(bfqd))) {
- 			switch_back_to_interactive_wr(bfqq, bfqd);
- 			bfq_log_bfqq(bfqq->bfqd, bfqq,
--			     "resume state: switching back to interactive");
-+			     "switching back to interactive");
- 		} else {
- 			bfqq->wr_coeff = 1;
- 			bfq_log_bfqq(bfqq->bfqd, bfqq,
--			     "resume state: switching off wr (%lu + %lu < %lu)",
-+			     "switching off wr (%lu + %lu < %lu)",
- 			     bfqq->last_wr_start_finish, bfqq->wr_cur_max_time,
- 			     jiffies);
- 		}
-@@ -985,7 +984,7 @@ static void bfq_add_to_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq)
- 	/* Increment burst size to take into account also bfqq */
- 	bfqd->burst_size++;
- 
--	bfq_log_bfqq(bfqd, bfqq, "add_to_burst %d", bfqd->burst_size);
-+	bfq_log_bfqq(bfqd, bfqq, "%d", bfqd->burst_size);
- 
- 	BUG_ON(bfqd->burst_size > bfqd->bfq_large_burst_thresh);
- 
-@@ -998,7 +997,7 @@ static void bfq_add_to_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq)
- 		 * other to consider this burst as large.
- 		 */
- 		bfqd->large_burst = true;
--		bfq_log_bfqq(bfqd, bfqq, "add_to_burst: large burst started");
-+		bfq_log_bfqq(bfqd, bfqq, "large burst started");
- 
- 		/*
- 		 * We can now mark all queues in the burst list as
-@@ -1170,7 +1169,7 @@ static void bfq_handle_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq)
- 		bfqd->large_burst = false;
- 		bfq_reset_burst_list(bfqd, bfqq);
- 		bfq_log_bfqq(bfqd, bfqq,
--			"handle_burst: late activation or different group");
-+			"late activation or different group");
- 		goto end;
- 	}
- 
-@@ -1180,7 +1179,7 @@ static void bfq_handle_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq)
- 	 * bfqq as belonging to this large burst immediately.
- 	 */
- 	if (bfqd->large_burst) {
--		bfq_log_bfqq(bfqd, bfqq, "handle_burst: marked in burst");
-+		bfq_log_bfqq(bfqd, bfqq, "marked in burst");
- 		bfq_mark_bfqq_in_large_burst(bfqq);
- 		goto end;
- 	}
-@@ -1686,7 +1685,7 @@ static void bfq_add_request(struct request *rq)
- 	unsigned int old_wr_coeff = bfqq->wr_coeff;
- 	bool interactive = false;
- 
--	bfq_log_bfqq(bfqd, bfqq, "add_request: size %u %s",
-+	bfq_log_bfqq(bfqd, bfqq, "size %u %s",
- 		     blk_rq_sectors(rq), rq_is_sync(rq) ? "S" : "A");
- 
- 	if (bfqq->wr_coeff > 1) /* queue is being weight-raised */
-@@ -1952,7 +1951,7 @@ static int bfq_request_merge(struct request_queue *q, struct request **req,
- 	__rq = bfq_find_rq_fmerge(bfqd, bio, q);
- 	if (__rq && elv_bio_merge_ok(__rq, bio)) {
- 		*req = __rq;
--		bfq_log(bfqd, "request_merge: req %p", __rq);
-+		bfq_log(bfqd, "req %p", __rq);
- 
- 		return ELEVATOR_FRONT_MERGE;
- 	}
-@@ -1989,7 +1988,7 @@ static void bfq_request_merged(struct request_queue *q, struct request *req,
- 		bfqq->next_rq = next_rq;
- 
- 		bfq_log_bfqq(bfqd, bfqq,
--			"request_merged: req %p prev %p next_rq %p bfqq %p",
-+			"req %p prev %p next_rq %p bfqq %p",
- 			     req, prev, next_rq, bfqq);
- 
- 		/*
-@@ -2018,7 +2017,7 @@ static void bfq_requests_merged(struct request_queue *q, struct request *rq,
- 		goto end;
- 
- 	bfq_log_bfqq(bfqq->bfqd, bfqq,
--		     "requests_merged: rq %p next %p bfqq %p next_bfqq %p",
-+		     "rq %p next %p bfqq %p next_bfqq %p",
- 		     rq, next, bfqq, next_bfqq);
- 
- 	spin_lock_irq(&bfqq->bfqd->lock);
-@@ -2069,10 +2068,10 @@ static void bfq_bfqq_end_wr(struct bfq_queue *bfqq)
- 	 */
- 	bfqq->entity.prio_changed = 1;
- 	bfq_log_bfqq(bfqq->bfqd, bfqq,
--		     "end_wr: wrais ending at %lu, rais_max_time %u",
-+		     "wrais ending at %lu, rais_max_time %u",
- 		     bfqq->last_wr_start_finish,
- 		     jiffies_to_msecs(bfqq->wr_cur_max_time));
--	bfq_log_bfqq(bfqq->bfqd, bfqq, "end_wr: wr_busy %d",
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "wr_busy %d",
- 		     bfqq->bfqd->wr_busy_queues);
- }
- 
-@@ -2245,8 +2244,8 @@ static bool bfq_may_be_close_cooperator(struct bfq_queue *bfqq,
- {
- 	if (bfq_too_late_for_merging(new_bfqq)) {
- 		bfq_log_bfqq(bfqq->bfqd, bfqq,
--			     "[%s] too late for bfq%d to be merged",
--			     __func__, new_bfqq->pid);
-+			     "too late for bfq%d to be merged",
-+				new_bfqq->pid);
- 		return false;
- 	}
- 
-@@ -2395,8 +2394,7 @@ static void bfq_bfqq_save_state(struct bfq_queue *bfqq)
- 	}
- 	BUG_ON(time_is_after_jiffies(bfqq->last_wr_start_finish));
- 	bfq_log_bfqq(bfqq->bfqd, bfqq,
--		     "[%s] bic %p wr_coeff %d start_finish %lu max_time %lu",
--		     __func__,
-+		     "bic %p wr_coeff %d start_finish %lu max_time %lu",
- 		     bic, bfqq->wr_coeff, bfqq->last_wr_start_finish,
- 		     bfqq->wr_cur_max_time);
- }
-@@ -2453,7 +2451,7 @@ bfq_merge_bfqqs(struct bfq_data *bfqd, struct bfq_io_cq *bic,
- 
- 	}
- 
--	bfq_log_bfqq(bfqd, new_bfqq, "merge_bfqqs: wr_busy %d",
-+	bfq_log_bfqq(bfqd, new_bfqq, "wr_busy %d",
- 		     bfqd->wr_busy_queues);
- 
- 	/*
-@@ -2554,7 +2552,7 @@ static void bfq_set_budget_timeout(struct bfq_data *bfqd,
- 	bfqq->budget_timeout = jiffies +
- 		bfqd->bfq_timeout * timeout_coeff;
- 
--	bfq_log_bfqq(bfqd, bfqq, "set budget_timeout %u",
-+	bfq_log_bfqq(bfqd, bfqq, "%u",
- 		jiffies_to_msecs(bfqd->bfq_timeout * timeout_coeff));
- }
- 
-@@ -2620,10 +2618,10 @@ static void __bfq_set_in_service_queue(struct bfq_data *bfqd,
- 
- 		bfq_set_budget_timeout(bfqd, bfqq);
- 		bfq_log_bfqq(bfqd, bfqq,
--			     "set_in_service_queue, cur-budget = %d",
-+			     "cur-budget = %d",
- 			     bfqq->entity.budget);
- 	} else
--		bfq_log(bfqd, "set_in_service_queue: NULL");
-+		bfq_log(bfqd, "NULL");
- 
- 	bfqd->in_service_queue = bfqq;
- }
-@@ -2746,7 +2744,7 @@ static void bfq_reset_rate_computation(struct bfq_data *bfqd, struct request *rq
- 		bfqd->peak_rate_samples = 0; /* full re-init on next disp. */
- 
- 	bfq_log(bfqd,
--		"reset_rate_computation at end, sample %u/%u tot_sects %llu",
-+		"at end, sample %u/%u tot_sects %llu",
- 		bfqd->peak_rate_samples, bfqd->sequential_samples,
- 		bfqd->tot_sectors_dispatched);
- }
-@@ -2766,7 +2764,7 @@ static void bfq_update_rate_reset(struct bfq_data *bfqd, struct request *rq)
- 	if (bfqd->peak_rate_samples < BFQ_RATE_MIN_SAMPLES ||
- 	    bfqd->delta_from_first < BFQ_RATE_MIN_INTERVAL) {
- 		bfq_log(bfqd,
--	"update_rate_reset: only resetting, delta_first %lluus samples %d",
-+	"only resetting, delta_first %lluus samples %d",
- 			bfqd->delta_from_first>>10, bfqd->peak_rate_samples);
- 		goto reset_computation;
- 	}
-@@ -2790,7 +2788,7 @@ static void bfq_update_rate_reset(struct bfq_data *bfqd, struct request *rq)
- 			div_u64(bfqd->delta_from_first, NSEC_PER_USEC));
- 
- 	bfq_log(bfqd,
--"update_rate_reset: tot_sects %llu delta_first %lluus rate %llu sects/s (%d)",
-+"tot_sects %llu delta_first %lluus rate %llu sects/s (%d)",
- 		bfqd->tot_sectors_dispatched, bfqd->delta_from_first>>10,
- 		((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT),
- 		rate > 20<<BFQ_RATE_SHIFT);
-@@ -2805,14 +2803,14 @@ static void bfq_update_rate_reset(struct bfq_data *bfqd, struct request *rq)
- 	     rate <= bfqd->peak_rate) ||
- 		rate > 20<<BFQ_RATE_SHIFT) {
- 		bfq_log(bfqd,
--		"update_rate_reset: goto reset, samples %u/%u rate/peak %llu/%llu",
-+		"goto reset, samples %u/%u rate/peak %llu/%llu",
- 		bfqd->peak_rate_samples, bfqd->sequential_samples,
- 		((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT),
- 		((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT));
- 		goto reset_computation;
- 	} else {
- 		bfq_log(bfqd,
--		"update_rate_reset: do update, samples %u/%u rate/peak %llu/%llu",
-+		"do update, samples %u/%u rate/peak %llu/%llu",
- 		bfqd->peak_rate_samples, bfqd->sequential_samples,
- 		((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT),
- 		((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT));
-@@ -2868,7 +2866,7 @@ static void bfq_update_rate_reset(struct bfq_data *bfqd, struct request *rq)
- 	rate /= divisor; /* smoothing constant alpha = 1/divisor */
- 
- 	bfq_log(bfqd,
--		"update_rate_reset: divisor %d tmp_peak_rate %llu tmp_rate %u",
-+		"divisor %d tmp_peak_rate %llu tmp_rate %u",
- 		divisor,
- 		((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT),
- 		(u32)((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT));
-@@ -2922,7 +2920,7 @@ static void bfq_update_peak_rate(struct bfq_data *bfqd, struct request *rq)
- 
- 	if (bfqd->peak_rate_samples == 0) { /* first dispatch */
- 		bfq_log(bfqd,
--		"update_peak_rate: goto reset, samples %d",
-+		"goto reset, samples %d",
- 				bfqd->peak_rate_samples) ;
- 		bfq_reset_rate_computation(bfqd, rq);
- 		goto update_last_values; /* will add one sample */
-@@ -2943,7 +2941,7 @@ static void bfq_update_peak_rate(struct bfq_data *bfqd, struct request *rq)
- 	if (now_ns - bfqd->last_dispatch > 100*NSEC_PER_MSEC &&
- 	    bfqd->rq_in_driver == 0) {
- 		bfq_log(bfqd,
--"update_peak_rate: jumping to updating&resetting delta_last %lluus samples %d",
-+"jumping to updating&resetting delta_last %lluus samples %d",
- 			(now_ns - bfqd->last_dispatch)>>10,
- 			bfqd->peak_rate_samples) ;
- 		goto update_rate_and_reset;
-@@ -2969,7 +2967,7 @@ static void bfq_update_peak_rate(struct bfq_data *bfqd, struct request *rq)
- 	bfqd->delta_from_first = now_ns - bfqd->first_dispatch;
- 
- 	bfq_log(bfqd,
--	"update_peak_rate: added samples %u/%u tot_sects %llu delta_first %lluus",
-+	"added samples %u/%u tot_sects %llu delta_first %lluus",
- 		bfqd->peak_rate_samples, bfqd->sequential_samples,
- 		bfqd->tot_sectors_dispatched,
- 		bfqd->delta_from_first>>10);
-@@ -2985,12 +2983,12 @@ static void bfq_update_peak_rate(struct bfq_data *bfqd, struct request *rq)
- 	bfqd->last_dispatch = now_ns;
- 
- 	bfq_log(bfqd,
--	"update_peak_rate: delta_first %lluus last_pos %llu peak_rate %llu",
-+	"delta_first %lluus last_pos %llu peak_rate %llu",
- 		(now_ns - bfqd->first_dispatch)>>10,
- 		(unsigned long long) bfqd->last_position,
- 		((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT));
- 	bfq_log(bfqd,
--	"update_peak_rate: samples at end %d", bfqd->peak_rate_samples);
-+	"samples at end %d", bfqd->peak_rate_samples);
- }
- 
- /*
-@@ -3088,11 +3086,11 @@ static void __bfq_bfqq_recalc_budget(struct bfq_data *bfqd,
- 	      */
- 		budget = 2 * min_budget;
- 
--	bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last budg %d, budg left %d",
-+	bfq_log_bfqq(bfqd, bfqq, "last budg %d, budg left %d",
- 		bfqq->entity.budget, bfq_bfqq_budget_left(bfqq));
--	bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last max_budg %d, min budg %d",
-+	bfq_log_bfqq(bfqd, bfqq, "last max_budg %d, min budg %d",
- 		budget, bfq_min_budget(bfqd));
--	bfq_log_bfqq(bfqd, bfqq, "recalc_budg: sync %d, seeky %d",
-+	bfq_log_bfqq(bfqd, bfqq, "sync %d, seeky %d",
- 		bfq_bfqq_sync(bfqq), BFQQ_SEEKY(bfqd->in_service_queue));
- 
- 	if (bfq_bfqq_sync(bfqq) && bfqq->wr_coeff == 1) {
-@@ -3294,7 +3292,7 @@ static bool bfq_bfqq_is_slow(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 		else /* charge at least one seek */
- 			*delta_ms = bfq_slice_idle / NSEC_PER_MSEC;
- 
--		bfq_log(bfqd, "bfq_bfqq_is_slow: too short %u", delta_usecs);
-+		bfq_log(bfqd, "too short %u", delta_usecs);
- 
- 		return slow;
- 	}
-@@ -3317,11 +3315,11 @@ static bool bfq_bfqq_is_slow(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 		 * peak rate.
- 		 */
- 		slow = bfqq->entity.service < bfqd->bfq_max_budget / 2;
--		bfq_log(bfqd, "bfq_bfqq_is_slow: relative rate %d/%d",
-+		bfq_log(bfqd, "relative rate %d/%d",
- 			bfqq->entity.service, bfqd->bfq_max_budget);
- 	}
- 
--	bfq_log_bfqq(bfqd, bfqq, "bfq_bfqq_is_slow: slow %d", slow);
-+	bfq_log_bfqq(bfqd, bfqq, "slow %d", slow);
- 
- 	return slow;
- }
-@@ -3423,7 +3421,7 @@ static unsigned long bfq_bfqq_softrt_next_start(struct bfq_data *bfqd,
- 						struct bfq_queue *bfqq)
- {
- 	bfq_log_bfqq(bfqd, bfqq,
--"softrt_next_start: service_blkg %lu soft_rate %u sects/sec interval %u",
-+"service_blkg %lu soft_rate %u sects/sec interval %u",
- 		     bfqq->service_from_backlogged,
- 		     bfqd->bfq_wr_max_softrt_rate,
- 		     jiffies_to_msecs(HZ * bfqq->service_from_backlogged /
-@@ -3602,7 +3600,7 @@ static bool bfq_bfqq_budget_timeout(struct bfq_queue *bfqq)
- static bool bfq_may_expire_for_budg_timeout(struct bfq_queue *bfqq)
- {
- 	bfq_log_bfqq(bfqq->bfqd, bfqq,
--		"may_budget_timeout: wait_request %d left %d timeout %d",
-+		"wait_request %d left %d timeout %d",
- 		bfq_bfqq_wait_request(bfqq),
- 			bfq_bfqq_budget_left(bfqq) >=  bfqq->entity.budget / 3,
- 		bfq_bfqq_budget_timeout(bfqq));
-@@ -3863,11 +3861,11 @@ static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq)
- 	 * either boosts the throughput (without issues), or is
- 	 * necessary to preserve service guarantees.
- 	 */
--	bfq_log_bfqq(bfqd, bfqq, "may_idle: sync %d idling_boosts_thr %d",
-+	bfq_log_bfqq(bfqd, bfqq, "sync %d idling_boosts_thr %d",
- 		     bfq_bfqq_sync(bfqq), idling_boosts_thr);
- 
- 	bfq_log_bfqq(bfqd, bfqq,
--		     "may_idle: wr_busy %d boosts %d IO-bound %d guar %d",
-+		     "wr_busy %d boosts %d IO-bound %d guar %d",
- 		     bfqd->wr_busy_queues,
- 		     idling_boosts_thr_without_issues,
- 		     bfq_bfqq_IO_bound(bfqq),
-@@ -3907,7 +3905,7 @@ static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd)
- 	if (!bfqq)
- 		goto new_queue;
- 
--	bfq_log_bfqq(bfqd, bfqq, "select_queue: already in-service queue");
-+	bfq_log_bfqq(bfqd, bfqq, "already in-service queue");
- 
- 	if (bfq_may_expire_for_budg_timeout(bfqq) &&
- 	    !bfq_bfqq_wait_request(bfqq) &&
-@@ -3983,14 +3981,14 @@ static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd)
- new_queue:
- 	bfqq = bfq_set_in_service_queue(bfqd);
- 	if (bfqq) {
--		bfq_log_bfqq(bfqd, bfqq, "select_queue: checking new queue");
-+		bfq_log_bfqq(bfqd, bfqq, "checking new queue");
- 		goto check_queue;
- 	}
- keep_queue:
- 	if (bfqq)
--		bfq_log_bfqq(bfqd, bfqq, "select_queue: returned this queue");
-+		bfq_log_bfqq(bfqd, bfqq, "returned this queue");
- 	else
--		bfq_log(bfqd, "select_queue: no queue returned");
-+		bfq_log(bfqd, "no queue returned");
- 
- 	return bfqq;
- }
-@@ -4043,8 +4041,7 @@ static void bfq_update_wr_data(struct bfq_data *bfqd, struct bfq_queue *bfqq)
- 			/* see comments on max_service_from_wr */
- 			bfq_bfqq_end_wr(bfqq);
- 			bfq_log_bfqq(bfqd, bfqq,
--				     "[%s] too much service",
--				     __func__);
-+				     "too much service");
- 		}
- 	}
- 	/*
-@@ -4122,7 +4119,7 @@ static bool bfq_has_work(struct blk_mq_hw_ctx *hctx)
- {
- 	struct bfq_data *bfqd = hctx->queue->elevator->elevator_data;
- 
--	bfq_log(bfqd, "has_work, dispatch_non_empty %d busy_queues %d",
-+	bfq_log(bfqd, "dispatch_non_empty %d busy_queues %d",
- 		!list_empty_careful(&bfqd->dispatch), bfqd->busy_queues > 0);
- 
- 	/*
-@@ -4146,7 +4143,7 @@ static struct request *__bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
- 		rq->rq_flags &= ~RQF_DISP_LIST;
- 
- 		bfq_log(bfqd,
--			"dispatch requests: picked %p from dispatch list", rq);
-+			"picked %p from dispatch list", rq);
- 		bfqq = RQ_BFQQ(rq);
- 
- 		if (bfqq) {
-@@ -4196,7 +4193,7 @@ static struct request *__bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
- 		goto start_rq;
- 	}
- 
--	bfq_log(bfqd, "dispatch requests: %d busy queues", bfqd->busy_queues);
-+	bfq_log(bfqd, "%d busy queues", bfqd->busy_queues);
- 
- 	if (bfqd->busy_queues == 0)
- 		goto exit;
-@@ -4236,13 +4233,13 @@ static struct request *__bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
- 		rq->rq_flags |= RQF_STARTED;
- 		if (bfqq)
- 			bfq_log_bfqq(bfqd, bfqq,
--				"dispatched %s request %p, rq_in_driver %d",
-+				"%s request %p, rq_in_driver %d",
- 				     bfq_bfqq_sync(bfqq) ? "sync" : "async",
- 				     rq,
- 				     bfqd->rq_in_driver);
- 		else
- 			bfq_log(bfqd,
--		"dispatched request %p from dispatch list, rq_in_driver %d",
-+		"request %p from dispatch list, rq_in_driver %d",
- 				rq, bfqd->rq_in_driver);
- 	} else
- 		bfq_log(bfqd,
-@@ -4339,7 +4336,7 @@ static void bfq_put_queue(struct bfq_queue *bfqq)
- 	BUG_ON(bfqq->ref <= 0);
- 
- 	if (bfqq->bfqd)
--		bfq_log_bfqq(bfqq->bfqd, bfqq, "put_queue: %p %d", bfqq, bfqq->ref);
-+		bfq_log_bfqq(bfqq->bfqd, bfqq, "%p %d", bfqq, bfqq->ref);
- 
- 	bfqq->ref--;
- 	if (bfqq->ref)
-@@ -4383,10 +4380,10 @@ static void bfq_put_queue(struct bfq_queue *bfqq)
- 	}
- 
- 	if (bfqq->bfqd)
--		bfq_log_bfqq(bfqq->bfqd, bfqq, "put_queue: %p freed", bfqq);
-+		bfq_log_bfqq(bfqq->bfqd, bfqq, "%p freed", bfqq);
- 
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
--	bfq_log_bfqq(bfqq->bfqd, bfqq, "[%s] putting blkg and bfqg %p\n", __func__, bfqg);
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "putting blkg and bfqg %p\n", bfqg);
- 	bfqg_and_blkg_put(bfqg);
- #endif
- 	kmem_cache_free(bfq_pool, bfqq);
-@@ -4418,7 +4415,7 @@ static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
- 		bfq_schedule_dispatch(bfqd);
- 	}
- 
--	bfq_log_bfqq(bfqd, bfqq, "exit_bfqq: %p, %d", bfqq, bfqq->ref);
-+	bfq_log_bfqq(bfqd, bfqq, "%p, %d", bfqq, bfqq->ref);
- 
- 	bfq_put_cooperator(bfqq);
- 
-@@ -4502,7 +4499,7 @@ static void bfq_set_next_ioprio_data(struct bfq_queue *bfqq,
- 	bfqq->entity.new_weight = bfq_ioprio_to_weight(bfqq->new_ioprio);
- 	bfqq->entity.prio_changed = 1;
- 	bfq_log_bfqq(bfqq->bfqd, bfqq,
--		     "set_next_ioprio_data: bic_class %d prio %d class %d",
-+		     "bic_class %d prio %d class %d",
- 		     ioprio_class, bfqq->new_ioprio, bfqq->new_ioprio_class);
- }
- 
-@@ -4529,7 +4526,7 @@ static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio)
- 		bfqq = bfq_get_queue(bfqd, bio, BLK_RW_ASYNC, bic);
- 		bic_set_bfqq(bic, bfqq, false);
- 		bfq_log_bfqq(bfqd, bfqq,
--			     "check_ioprio_change: bfqq %p %d",
-+			     "bfqq %p %d",
- 			     bfqq, bfqq->ref);
- 	}
- 
-@@ -4667,14 +4664,14 @@ static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd,
- 			      * guarantee that this queue is not freed
- 			      * until its group goes away.
- 			      */
--		bfq_log_bfqq(bfqd, bfqq, "get_queue, bfqq not in async: %p, %d",
-+		bfq_log_bfqq(bfqd, bfqq, "bfqq not in async: %p, %d",
- 			     bfqq, bfqq->ref);
- 		*async_bfqq = bfqq;
- 	}
- 
- out:
- 	bfqq->ref++; /* get a process reference to this queue */
--	bfq_log_bfqq(bfqd, bfqq, "get_queue, at end: %p, %d", bfqq, bfqq->ref);
-+	bfq_log_bfqq(bfqd, bfqq, "at end: %p, %d", bfqq, bfqq->ref);
- 	rcu_read_unlock();
- 	return bfqq;
- }
-@@ -4733,7 +4730,7 @@ static void bfq_update_has_short_ttime(struct bfq_data *bfqd,
- 	     bfqq->ttime.ttime_mean > bfqd->bfq_slice_idle))
- 		has_short_ttime = false;
- 
--	bfq_log_bfqq(bfqd, bfqq, "update_has_short_ttime: has_short_ttime %d",
-+	bfq_log_bfqq(bfqd, bfqq, "has_short_ttime %d",
- 		has_short_ttime);
- 
- 	if (has_short_ttime)
-@@ -4759,7 +4756,7 @@ static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 	bfq_update_io_seektime(bfqd, bfqq, rq);
- 
- 	bfq_log_bfqq(bfqd, bfqq,
--		     "rq_enqueued: has_short_ttime=%d (seeky %d)",
-+		     "has_short_ttime=%d (seeky %d)",
- 		     bfq_bfqq_has_short_ttime(bfqq), BFQQ_SEEKY(bfqq));
- 
- 	bfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
-@@ -4818,7 +4815,7 @@ static bool __bfq_insert_request(struct bfq_data *bfqd, struct request *rq)
- 
- 	assert_spin_locked(&bfqd->lock);
- 
--	bfq_log_bfqq(bfqd, bfqq, "__insert_req: rq %p bfqq %p", rq, bfqq);
-+	bfq_log_bfqq(bfqd, bfqq, "rq %p bfqq %p", rq, bfqq);
- 
- 	/*
- 	 * An unplug may trigger a requeue of a request from the device
-@@ -4837,9 +4834,9 @@ static bool __bfq_insert_request(struct bfq_data *bfqd, struct request *rq)
- 			new_bfqq->allocated++;
- 			bfqq->allocated--;
- 			bfq_log_bfqq(bfqd, bfqq,
--		     "insert_request: new allocated %d", bfqq->allocated);
-+		     "new allocated %d", bfqq->allocated);
- 			bfq_log_bfqq(bfqd, new_bfqq,
--		     "insert_request: new_bfqq new allocated %d",
-+		     "new_bfqq new allocated %d",
- 				     bfqq->allocated);
- 
- 			new_bfqq->ref++;
-@@ -4911,11 +4908,11 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
- 		rq->rq_flags |= RQF_DISP_LIST;
- 		if (bfqq)
- 			bfq_log_bfqq(bfqd, bfqq,
--				     "insert_request %p in disp: at_head %d",
-+				     "%p in disp: at_head %d",
- 				     rq, at_head);
- 		else
- 			bfq_log(bfqd,
--				"insert_request %p in disp: at_head %d",
-+				"%p in disp: at_head %d",
- 				rq, at_head);
- 	} else {
- 		BUG_ON(!(rq->rq_flags & RQF_GOT));
-@@ -5033,7 +5030,7 @@ static void bfq_completed_request(struct bfq_queue *bfqq, struct bfq_data *bfqd)
- 	bfqq->dispatched--;
- 
- 	bfq_log_bfqq(bfqd, bfqq,
--		     "completed_requests: new disp %d, new rq_in_driver %d",
-+		     "new disp %d, new rq_in_driver %d",
- 		     bfqq->dispatched, bfqd->rq_in_driver);
- 
- 	if (!bfqq->dispatched && !bfq_bfqq_busy(bfqq)) {
-@@ -5061,7 +5058,7 @@ static void bfq_completed_request(struct bfq_queue *bfqq, struct bfq_data *bfqd)
- 	delta_us = div_u64(now_ns - bfqd->last_completion, NSEC_PER_USEC);
- 
- 	bfq_log_bfqq(bfqd, bfqq,
--		"rq_completed: delta %uus/%luus max_size %u rate %llu/%llu",
-+		"delta %uus/%luus max_size %u rate %llu/%llu",
- 		delta_us, BFQ_MIN_TT/NSEC_PER_USEC, bfqd->last_rq_max_size,
- 		delta_us > 0 ?
- 		(USEC_PER_SEC*
-@@ -5129,7 +5126,7 @@ static void bfq_completed_request(struct bfq_queue *bfqq, struct bfq_data *bfqd)
- static void bfq_finish_requeue_request_body(struct bfq_queue *bfqq)
- {
- 	bfq_log_bfqq(bfqq->bfqd, bfqq,
--		     "put_request_body: allocated %d", bfqq->allocated);
-+		     "allocated %d", bfqq->allocated);
- 	BUG_ON(!bfqq->allocated);
- 	bfqq->allocated--;
- 
-@@ -5406,10 +5403,10 @@ static void bfq_prepare_request(struct request *rq, struct bio *bio)
- 
- 	bfqq->allocated++;
- 	bfq_log_bfqq(bfqq->bfqd, bfqq,
--		     "get_request: new allocated %d", bfqq->allocated);
-+		     "new allocated %d", bfqq->allocated);
- 
- 	bfqq->ref++;
--	bfq_log_bfqq(bfqd, bfqq, "get_request %p: bfqq %p, %d", rq, bfqq, bfqq->ref);
-+	bfq_log_bfqq(bfqd, bfqq, "%p: bfqq %p, %d", rq, bfqq, bfqq->ref);
- 
- 	rq->elv.priv[0] = bic;
- 	rq->elv.priv[1] = bfqq;
-@@ -5493,7 +5490,7 @@ static enum hrtimer_restart bfq_idle_slice_timer(struct hrtimer *timer)
- 					     idle_slice_timer);
- 	struct bfq_queue *bfqq = bfqd->in_service_queue;
- 
--	bfq_log(bfqd, "slice_timer expired");
-+	bfq_log(bfqd, "expired");
- 
- 	/*
- 	 * Theoretical race here: the in-service queue can be NULL or
-@@ -5515,10 +5512,10 @@ static void __bfq_put_async_bfqq(struct bfq_data *bfqd,
- 	struct bfq_group *root_group = bfqd->root_group;
- 	struct bfq_queue *bfqq = *bfqq_ptr;
- 
--	bfq_log(bfqd, "put_async_bfqq: %p", bfqq);
-+	bfq_log(bfqd, "%p", bfqq);
- 	if (bfqq) {
- 		bfq_bfqq_move(bfqd, bfqq, root_group);
--		bfq_log_bfqq(bfqd, bfqq, "put_async_bfqq: putting %p, %d",
-+		bfq_log_bfqq(bfqd, bfqq, "putting %p, %d",
- 			     bfqq, bfqq->ref);
- 		bfq_put_queue(bfqq);
- 		*bfqq_ptr = NULL;
-@@ -5547,7 +5544,7 @@ static void bfq_exit_queue(struct elevator_queue *e)
- 	struct bfq_data *bfqd = e->elevator_data;
- 	struct bfq_queue *bfqq, *n;
- 
--	bfq_log(bfqd, "exit_queue: starting ...");
-+	bfq_log(bfqd, "starting ...");
- 
- 	hrtimer_cancel(&bfqd->idle_slice_timer);
- 
-@@ -5575,7 +5572,7 @@ static void bfq_exit_queue(struct elevator_queue *e)
- 	spin_unlock_irq(&bfqd->lock);
- #endif
- 
--	bfq_log(bfqd, "exit_queue: finished ...");
-+	bfq_log(bfqd, "finished ...");
- 	kfree(bfqd);
- }
- 
-diff --git a/block/bfq-mq.h b/block/bfq-mq.h
-index 9a5ce1168ff5..e2ae11bf8f76 100644
---- a/block/bfq-mq.h
-+++ b/block/bfq-mq.h
-@@ -712,34 +712,34 @@ static struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
- static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
- 
- #define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	do {			\
--	pr_crit("%s bfq%d%c %s " fmt "\n", 				\
-+	pr_crit("%s bfq%d%c %s [%s] " fmt "\n",				\
- 		checked_dev_name((bfqd)->queue->backing_dev_info->dev),	\
- 		(bfqq)->pid,						\
- 		bfq_bfqq_sync((bfqq)) ? 'S' : 'A',			\
--		bfqq_group(bfqq)->blkg_path, ##args);			\
-+		bfqq_group(bfqq)->blkg_path, __func__, ##args);		\
- } while (0)
- 
- #define bfq_log_bfqg(bfqd, bfqg, fmt, args...)	do {			\
--	pr_crit("%s %s " fmt "\n",					\
-+	pr_crit("%s %s [%s] " fmt "\n",					\
- 	checked_dev_name((bfqd)->queue->backing_dev_info->dev),		\
--	bfqg->blkg_path, ##args);					\
-+	bfqg->blkg_path, __func__, ##args);				\
- } while (0)
- 
- #else /* BFQ_GROUP_IOSCHED_ENABLED */
- 
- #define bfq_log_bfqq(bfqd, bfqq, fmt, args...)				\
--	pr_crit("%s bfq%d%c " fmt "\n",					\
-+	pr_crit("%s bfq%d%c [%s] " fmt "\n",				\
- 		checked_dev_name((bfqd)->queue->backing_dev_info->dev),	\
- 		(bfqq)->pid, bfq_bfqq_sync((bfqq)) ? 'S' : 'A',		\
--		##args)
-+		__func__, ##args)
- #define bfq_log_bfqg(bfqd, bfqg, fmt, args...)		do {} while (0)
- 
- #endif /* BFQ_GROUP_IOSCHED_ENABLED */
- 
- #define bfq_log(bfqd, fmt, args...) \
--	pr_crit("%s bfq " fmt "\n",					\
-+	pr_crit("%s bfq [%s] " fmt "\n",				\
- 		checked_dev_name((bfqd)->queue->backing_dev_info->dev),	\
--		##args)
-+		__func__, ##args)
- 
- #else /* CONFIG_BFQ_REDIRECT_TO_CONSOLE */
- 
-@@ -762,28 +762,29 @@ static struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
- static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
- 
- #define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	do {			\
--	blk_add_trace_msg((bfqd)->queue, "bfq%d%c %s " fmt, \
-+	blk_add_trace_msg((bfqd)->queue, "bfq%d%c %s [%s] " fmt, \
- 			  (bfqq)->pid,			  \
- 			  bfq_bfqq_sync((bfqq)) ? 'S' : 'A',	\
--			  bfqq_group(bfqq)->blkg_path, ##args);		\
-+			  bfqq_group(bfqq)->blkg_path, __func__, ##args); \
- } while (0)
- 
- #define bfq_log_bfqg(bfqd, bfqg, fmt, args...)	do {			\
--	blk_add_trace_msg((bfqd)->queue, "%s " fmt, bfqg->blkg_path, ##args);\
-+	blk_add_trace_msg((bfqd)->queue, "%s [%s] " fmt, bfqg->blkg_path, \
-+	__func__, ##args);\
- } while (0)
- 
- #else /* BFQ_GROUP_IOSCHED_ENABLED */
- 
- #define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	\
--	blk_add_trace_msg((bfqd)->queue, "bfq%d%c " fmt, (bfqq)->pid,	\
-+	blk_add_trace_msg((bfqd)->queue, "bfq%d%c [%s] " fmt, (bfqq)->pid, \
- 			bfq_bfqq_sync((bfqq)) ? 'S' : 'A',		\
--				##args)
-+				__func__, ##args)
- #define bfq_log_bfqg(bfqd, bfqg, fmt, args...)		do {} while (0)
- 
- #endif /* BFQ_GROUP_IOSCHED_ENABLED */
- 
- #define bfq_log(bfqd, fmt, args...) \
--	blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args)
-+	blk_add_trace_msg((bfqd)->queue, "bfq [%s] " fmt, __func__, ##args)
- 
- #endif /* CONFIG_BLK_DEV_IO_TRACE */
- #endif /* CONFIG_BFQ_REDIRECT_TO_CONSOLE */
-@@ -938,7 +939,7 @@ bfq_entity_service_tree(struct bfq_entity *entity)
- 
- 	if (bfqq)
- 		bfq_log_bfqq(bfqq->bfqd, bfqq,
--			     "entity_service_tree %p %d",
-+			     "%p %d",
- 			     sched_data->service_tree + idx, idx);
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	else {
-@@ -946,7 +947,7 @@ bfq_entity_service_tree(struct bfq_entity *entity)
- 			container_of(entity, struct bfq_group, entity);
- 
- 		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
--			     "entity_service_tree %p %d",
-+			     "%p %d",
- 			     sched_data->service_tree + idx, idx);
- 	}
- #endif
-diff --git a/block/bfq-sched.c b/block/bfq-sched.c
-index 4e6c5232e2fb..ead34c30a7c2 100644
---- a/block/bfq-sched.c
-+++ b/block/bfq-sched.c
-@@ -119,7 +119,7 @@ static bool bfq_update_next_in_service(struct bfq_sched_data *sd,
- 
- 			if (bfqq)
- 				bfq_log_bfqq(bfqq->bfqd, bfqq,
--				"update_next_in_service: chose without lookup");
-+				"chose without lookup");
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
- 			else {
- 				struct bfq_group *bfqg =
-@@ -127,7 +127,7 @@ static bool bfq_update_next_in_service(struct bfq_sched_data *sd,
- 						     struct bfq_group, entity);
- 
- 				bfq_log_bfqg((struct bfq_data*)bfqg->bfqd, bfqg,
--				"update_next_in_service: chose without lookup");
-+				"chose without lookup");
- 			}
- #endif
- 		}
-@@ -148,7 +148,7 @@ static bool bfq_update_next_in_service(struct bfq_sched_data *sd,
- 	bfqq = bfq_entity_to_bfqq(next_in_service);
- 	if (bfqq)
- 		bfq_log_bfqq(bfqq->bfqd, bfqq,
--			     "update_next_in_service: chosen this queue");
-+			     "chosen this queue");
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	else {
- 		struct bfq_group *bfqg =
-@@ -156,7 +156,7 @@ static bool bfq_update_next_in_service(struct bfq_sched_data *sd,
- 				     struct bfq_group, entity);
- 
- 		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
--			     "update_next_in_service: chosen this entity");
-+			     "chosen this entity");
- 	}
- #endif
- 	return parent_sched_may_change;
-@@ -331,10 +331,10 @@ static void bfq_calc_finish(struct bfq_entity *entity, unsigned long service)
- 
- 	if (bfqq) {
- 		bfq_log_bfqq(bfqq->bfqd, bfqq,
--			"calc_finish: serv %lu, w %d",
-+			"serv %lu, w %d",
- 			service, entity->weight);
- 		bfq_log_bfqq(bfqq->bfqd, bfqq,
--			"calc_finish: start %llu, finish %llu, delta %llu",
-+			"start %llu, finish %llu, delta %llu",
- 			start, finish, delta);
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	} else {
-@@ -342,10 +342,10 @@ static void bfq_calc_finish(struct bfq_entity *entity, unsigned long service)
- 			container_of(entity, struct bfq_group, entity);
- 
- 		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
--			"calc_finish group: serv %lu, w %d",
-+			"group: serv %lu, w %d",
- 			     service, entity->weight);
- 		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
--			"calc_finish group: start %llu, finish %llu, delta %llu",
-+			"group: start %llu, finish %llu, delta %llu",
- 			start, finish, delta);
- #endif
- 	}
-@@ -484,7 +484,7 @@ static void bfq_update_active_node(struct rb_node *node)
- 
- 	if (bfqq) {
- 		bfq_log_bfqq(bfqq->bfqd, bfqq,
--			     "update_active_node: new min_start %llu",
-+			     "new min_start %llu",
- 			     ((entity->min_start>>10)*1000)>>12);
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	} else {
-@@ -492,7 +492,7 @@ static void bfq_update_active_node(struct rb_node *node)
- 			container_of(entity, struct bfq_group, entity);
- 
- 		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
--			     "update_active_node: new min_start %llu",
-+			     "new min_start %llu",
- 			     ((entity->min_start>>10)*1000)>>12);
- #endif
- 	}
-@@ -620,7 +620,7 @@ static void bfq_get_entity(struct bfq_entity *entity)
- 
- 	if (bfqq) {
- 		bfqq->ref++;
--		bfq_log_bfqq(bfqq->bfqd, bfqq, "get_entity: %p %d",
-+		bfq_log_bfqq(bfqq->bfqd, bfqq, "%p %d",
- 			     bfqq, bfqq->ref);
- 	}
- }
-@@ -748,7 +748,7 @@ static void bfq_forget_entity(struct bfq_service_tree *st,
- 	entity->on_st = false;
- 	st->wsum -= entity->weight;
- 	if (bfqq && !is_in_service) {
--		bfq_log_bfqq(bfqq->bfqd, bfqq, "forget_entity (before): %p %d",
-+		bfq_log_bfqq(bfqq->bfqd, bfqq, "(before): %p %d",
- 			     bfqq, bfqq->ref);
- 		bfq_put_queue(bfqq);
- 	}
-@@ -1008,7 +1008,7 @@ static void bfq_bfqq_charge_time(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 		tot_serv_to_charge = entity->service;
- 
- 	bfq_log_bfqq(bfqq->bfqd, bfqq,
--		     "charge_time: %lu/%u ms, %d/%d/%d sectors",
-+		     "%lu/%u ms, %d/%d/%d sectors",
- 		     time_ms, timeout_ms, entity->service,
- 		     tot_serv_to_charge, entity->budget);
- 
-@@ -1080,7 +1080,7 @@ static void bfq_update_fin_time_enqueue(struct bfq_entity *entity,
- 
- 		if (bfqq) {
- 			bfq_log_bfqq(bfqq->bfqd, bfqq,
--				     "update_fin_time_enqueue: new queue finish %llu",
-+				     "new queue finish %llu",
- 				     ((entity->finish>>10)*1000)>>12);
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
- 		} else {
-@@ -1088,7 +1088,7 @@ static void bfq_update_fin_time_enqueue(struct bfq_entity *entity,
- 				container_of(entity, struct bfq_group, entity);
- 
- 			bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
--				     "update_fin_time_enqueue: new group finish %llu",
-+				     "new group finish %llu",
- 				     ((entity->finish>>10)*1000)>>12);
- #endif
- 		}
-@@ -1098,7 +1098,7 @@ static void bfq_update_fin_time_enqueue(struct bfq_entity *entity,
- 
- 	if (bfqq) {
- 		bfq_log_bfqq(bfqq->bfqd, bfqq,
--			"update_fin_time_enqueue: queue %seligible in st %p",
-+			"queue %seligible in st %p",
- 			     entity->start <= st->vtime ? "" : "non ", st);
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	} else {
-@@ -1106,7 +1106,7 @@ static void bfq_update_fin_time_enqueue(struct bfq_entity *entity,
- 			container_of(entity, struct bfq_group, entity);
- 
- 		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
--			"update_fin_time_enqueue: group %seligible in st %p",
-+			"group %seligible in st %p",
- 			     entity->start <= st->vtime ? "" : "non ", st);
- #endif
- 	}
-@@ -1550,7 +1550,7 @@ static u64 bfq_calc_vtime_jump(struct bfq_service_tree *st)
- 
- 		if (bfqq)
- 			bfq_log_bfqq(bfqq->bfqd, bfqq,
--				     "calc_vtime_jump: new value %llu",
-+				     "new value %llu",
- 				     ((root_entity->min_start>>10)*1000)>>12);
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
- 		else {
-@@ -1559,7 +1559,7 @@ static u64 bfq_calc_vtime_jump(struct bfq_service_tree *st)
- 					     entity);
- 
- 			bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
--				     "calc_vtime_jump: new value %llu",
-+				     "new value %llu",
- 				     ((root_entity->min_start>>10)*1000)>>12);
- 		}
- #endif
-@@ -1677,7 +1677,7 @@ __bfq_lookup_next_entity(struct bfq_service_tree *st, bool in_service)
- 	bfqq = bfq_entity_to_bfqq(entity);
- 	if (bfqq)
- 		bfq_log_bfqq(bfqq->bfqd, bfqq,
--			     "__lookup_next: start %llu vtime %llu st %p",
-+			     "start %llu vtime %llu st %p",
- 			     ((entity->start>>10)*1000)>>12,
- 			     ((new_vtime>>10)*1000)>>12, st);
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
-@@ -1686,7 +1686,7 @@ __bfq_lookup_next_entity(struct bfq_service_tree *st, bool in_service)
- 			container_of(entity, struct bfq_group, entity);
- 
- 		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
--			     "__lookup_next: start %llu vtime %llu (%llu) st %p",
-+			     "start %llu vtime %llu (%llu) st %p",
- 			     ((entity->start>>10)*1000)>>12,
- 			     ((st->vtime>>10)*1000)>>12,
- 			     ((new_vtime>>10)*1000)>>12, st);
-@@ -1821,14 +1821,14 @@ static struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd)
- 				container_of(entity, struct bfq_group, entity);
- 
- 			bfq_log_bfqg(bfqd, bfqg,
--				     "get_next_queue: lookup in this group");
-+				     "lookup in this group");
- 			if (!sd->next_in_service)
--				pr_crit("get_next_queue: lookup in this group");
-+				pr_crit("lookup in this group");
- 		} else {
- 			bfq_log_bfqg(bfqd, bfqd->root_group,
--				     "get_next_queue: lookup in root group");
-+				     "lookup in root group");
- 			if (!sd->next_in_service)
--				pr_crit("get_next_queue: lookup in root group");
-+				pr_crit("lookup in root group");
- 		}
- #endif
- 
-@@ -1903,7 +1903,7 @@ static struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd)
- 		bfqq = bfq_entity_to_bfqq(entity);
- 		if (bfqq)
- 			bfq_log_bfqq(bfqd, bfqq,
--			     "get_next_queue: this queue, finish %llu",
-+			     "this queue, finish %llu",
- 				(((entity->finish>>10)*1000)>>10)>>2);
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
- 		else {
-@@ -1911,7 +1911,7 @@ static struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd)
- 				container_of(entity, struct bfq_group, entity);
- 
- 			bfq_log_bfqg(bfqd, bfqg,
--			     "get_next_queue: this entity, finish %llu",
-+			     "this entity, finish %llu",
- 				(((entity->finish>>10)*1000)>>10)>>2);
- 		}
- #endif
-diff --git a/block/bfq-sq-iosched.c b/block/bfq-sq-iosched.c
-index c4df156b1fb4..e49e8ac882b3 100644
---- a/block/bfq-sq-iosched.c
-+++ b/block/bfq-sq-iosched.c
-@@ -281,7 +281,7 @@ static void bfq_schedule_dispatch(struct bfq_data *bfqd);
- static void bfq_schedule_dispatch(struct bfq_data *bfqd)
- {
- 	if (bfqd->queued != 0) {
--		bfq_log(bfqd, "schedule dispatch");
-+		bfq_log(bfqd, "");
- 		kblockd_schedule_work(&bfqd->unplug_work);
- 	}
- }
-@@ -414,7 +414,7 @@ bfq_rq_pos_tree_lookup(struct bfq_data *bfqd, struct rb_root *root,
- 	if (rb_link)
- 		*rb_link = p;
- 
--	bfq_log(bfqd, "rq_pos_tree_lookup %llu: returning %d",
-+	bfq_log(bfqd, "%llu: returning %d",
- 		(unsigned long long) sector,
- 		bfqq ? bfqq->pid : 0);
- 
-@@ -635,7 +635,7 @@ static struct request *bfq_check_fifo(struct bfq_queue *bfqq,
- 	if (rq == last || ktime_get_ns() < rq->fifo_time)
- 		return NULL;
- 
--	bfq_log_bfqq(bfqq->bfqd, bfqq, "check_fifo: returned %p", rq);
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "returned %p", rq);
- 	BUG_ON(RB_EMPTY_NODE(&rq->rb_node));
- 	return rq;
- }
-@@ -728,7 +728,7 @@ static void bfq_updated_next_req(struct bfq_data *bfqd,
- 			   bfq_serv_to_charge(next_rq, bfqq));
- 	if (entity->budget != new_budget) {
- 		entity->budget = new_budget;
--		bfq_log_bfqq(bfqd, bfqq, "updated next rq: new budget %lu",
-+		bfq_log_bfqq(bfqd, bfqq, "new budget %lu",
- 					 new_budget);
- 		bfq_requeue_bfqq(bfqd, bfqq, false);
- 	}
-@@ -800,8 +800,7 @@ bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_data *bfqd,
- 	BUG_ON(time_is_after_jiffies(bfqq->last_wr_start_finish));
- 
- 	bfq_log_bfqq(bfqq->bfqd, bfqq,
--		     "[%s] bic %p wr_coeff %d start_finish %lu max_time %lu",
--		     __func__,
-+		     "bic %p wr_coeff %d start_finish %lu max_time %lu",
- 		     bic, bfqq->wr_coeff, bfqq->last_wr_start_finish,
- 		     bfqq->wr_cur_max_time);
- 
-@@ -814,11 +813,11 @@ bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_data *bfqd,
- 					     bfq_wr_duration(bfqd))) {
- 			switch_back_to_interactive_wr(bfqq, bfqd);
- 			bfq_log_bfqq(bfqq->bfqd, bfqq,
--			     "resume state: switching back to interactive");
-+			     "switching back to interactive");
- 		} else {
- 			bfqq->wr_coeff = 1;
- 			bfq_log_bfqq(bfqq->bfqd, bfqq,
--			     "resume state: switching off wr (%lu + %lu < %lu)",
-+			     "switching off wr (%lu + %lu < %lu)",
- 			     bfqq->last_wr_start_finish, bfqq->wr_cur_max_time,
- 			     jiffies);
- 		}
-@@ -870,7 +869,7 @@ static void bfq_add_to_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq)
- 	/* Increment burst size to take into account also bfqq */
- 	bfqd->burst_size++;
- 
--	bfq_log_bfqq(bfqd, bfqq, "add_to_burst %d", bfqd->burst_size);
-+	bfq_log_bfqq(bfqd, bfqq, "%d", bfqd->burst_size);
- 
- 	BUG_ON(bfqd->burst_size > bfqd->bfq_large_burst_thresh);
- 
-@@ -883,7 +882,7 @@ static void bfq_add_to_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq)
- 		 * other to consider this burst as large.
- 		 */
- 		bfqd->large_burst = true;
--		bfq_log_bfqq(bfqd, bfqq, "add_to_burst: large burst started");
-+		bfq_log_bfqq(bfqd, bfqq, "large burst started");
- 
- 		/*
- 		 * We can now mark all queues in the burst list as
-@@ -1055,7 +1054,7 @@ static void bfq_handle_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq)
- 		bfqd->large_burst = false;
- 		bfq_reset_burst_list(bfqd, bfqq);
- 		bfq_log_bfqq(bfqd, bfqq,
--			"handle_burst: late activation or different group");
-+			"late activation or different group");
- 		goto end;
- 	}
- 
-@@ -1065,7 +1064,7 @@ static void bfq_handle_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq)
- 	 * bfqq as belonging to this large burst immediately.
- 	 */
- 	if (bfqd->large_burst) {
--		bfq_log_bfqq(bfqd, bfqq, "handle_burst: marked in burst");
-+		bfq_log_bfqq(bfqd, bfqq, "marked in burst");
- 		bfq_mark_bfqq_in_large_burst(bfqq);
- 		goto end;
- 	}
-@@ -1572,7 +1571,7 @@ static void bfq_add_request(struct request *rq)
- 	unsigned int old_wr_coeff = bfqq->wr_coeff;
- 	bool interactive = false;
- 
--	bfq_log_bfqq(bfqd, bfqq, "add_request: size %u %s",
-+	bfq_log_bfqq(bfqd, bfqq, "size %u %s",
- 		     blk_rq_sectors(rq), rq_is_sync(rq) ? "S" : "A");
- 
- 	if (bfqq->wr_coeff > 1) /* queue is being weight-raised */
-@@ -1870,10 +1869,10 @@ static void bfq_bfqq_end_wr(struct bfq_queue *bfqq)
- 	 */
- 	bfqq->entity.prio_changed = 1;
- 	bfq_log_bfqq(bfqq->bfqd, bfqq,
--		     "end_wr: wrais ending at %lu, rais_max_time %u",
-+		     "wrais ending at %lu, rais_max_time %u",
- 		     bfqq->last_wr_start_finish,
- 		     jiffies_to_msecs(bfqq->wr_cur_max_time));
--	bfq_log_bfqq(bfqq->bfqd, bfqq, "end_wr: wr_busy %d",
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "wr_busy %d",
- 		     bfqq->bfqd->wr_busy_queues);
- }
- 
-@@ -2048,8 +2047,8 @@ static bool bfq_may_be_close_cooperator(struct bfq_queue *bfqq,
- {
- 	if (bfq_too_late_for_merging(new_bfqq)) {
- 		bfq_log_bfqq(bfqq->bfqd, bfqq,
--			     "[%s] too late for bfq%d to be merged",
--			     __func__, new_bfqq->pid);
-+			     "too late for bfq%d to be merged",
-+				new_bfqq->pid);
- 		return false;
- 	}
- 
-@@ -2258,7 +2257,7 @@ bfq_merge_bfqqs(struct bfq_data *bfqd, struct bfq_io_cq *bic,
- 
- 	}
- 
--	bfq_log_bfqq(bfqd, new_bfqq, "merge_bfqqs: wr_busy %d",
-+	bfq_log_bfqq(bfqd, new_bfqq, "wr_busy %d",
- 		     bfqd->wr_busy_queues);
- 
- 	/*
-@@ -2359,7 +2358,7 @@ static void bfq_set_budget_timeout(struct bfq_data *bfqd,
- 	bfqq->budget_timeout = jiffies +
- 		bfqd->bfq_timeout * timeout_coeff;
- 
--	bfq_log_bfqq(bfqd, bfqq, "set budget_timeout %u",
-+	bfq_log_bfqq(bfqd, bfqq, "%u",
- 		jiffies_to_msecs(bfqd->bfq_timeout * timeout_coeff));
- }
- 
-@@ -2427,10 +2426,10 @@ static void __bfq_set_in_service_queue(struct bfq_data *bfqd,
- 
- 		bfq_set_budget_timeout(bfqd, bfqq);
- 		bfq_log_bfqq(bfqd, bfqq,
--			     "set_in_service_queue, cur-budget = %d",
-+			     "cur-budget = %d",
- 			     bfqq->entity.budget);
- 	} else
--		bfq_log(bfqd, "set_in_service_queue: NULL");
-+		bfq_log(bfqd, "NULL");
- 
- 	bfqd->in_service_queue = bfqq;
- }
-@@ -2559,7 +2558,7 @@ static void bfq_reset_rate_computation(struct bfq_data *bfqd, struct request *rq
- 		bfqd->peak_rate_samples = 0; /* full re-init on next disp. */
- 
- 	bfq_log(bfqd,
--		"reset_rate_computation at end, sample %u/%u tot_sects %llu",
-+		"at end, sample %u/%u tot_sects %llu",
- 		bfqd->peak_rate_samples, bfqd->sequential_samples,
- 		bfqd->tot_sectors_dispatched);
- }
-@@ -2579,7 +2578,7 @@ static void bfq_update_rate_reset(struct bfq_data *bfqd, struct request *rq)
- 	if (bfqd->peak_rate_samples < BFQ_RATE_MIN_SAMPLES ||
- 	    bfqd->delta_from_first < BFQ_RATE_MIN_INTERVAL) {
- 		bfq_log(bfqd,
--	"update_rate_reset: only resetting, delta_first %lluus samples %d",
-+	"only resetting, delta_first %lluus samples %d",
- 			bfqd->delta_from_first>>10, bfqd->peak_rate_samples);
- 		goto reset_computation;
- 	}
-@@ -2603,7 +2602,7 @@ static void bfq_update_rate_reset(struct bfq_data *bfqd, struct request *rq)
- 			div_u64(bfqd->delta_from_first, NSEC_PER_USEC));
- 
- 	bfq_log(bfqd,
--"update_rate_reset: tot_sects %llu delta_first %lluus rate %llu sects/s (%d)",
-+"tot_sects %llu delta_first %lluus rate %llu sects/s (%d)",
- 		bfqd->tot_sectors_dispatched, bfqd->delta_from_first>>10,
- 		((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT),
- 		rate > 20<<BFQ_RATE_SHIFT);
-@@ -2618,14 +2617,14 @@ static void bfq_update_rate_reset(struct bfq_data *bfqd, struct request *rq)
- 	     rate <= bfqd->peak_rate) ||
- 		rate > 20<<BFQ_RATE_SHIFT) {
- 		bfq_log(bfqd,
--		"update_rate_reset: goto reset, samples %u/%u rate/peak %llu/%llu",
-+		"goto reset, samples %u/%u rate/peak %llu/%llu",
- 		bfqd->peak_rate_samples, bfqd->sequential_samples,
- 		((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT),
- 		((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT));
- 		goto reset_computation;
- 	} else {
- 		bfq_log(bfqd,
--		"update_rate_reset: do update, samples %u/%u rate/peak %llu/%llu",
-+		"do update, samples %u/%u rate/peak %llu/%llu",
- 		bfqd->peak_rate_samples, bfqd->sequential_samples,
- 		((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT),
- 		((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT));
-@@ -2681,7 +2680,7 @@ static void bfq_update_rate_reset(struct bfq_data *bfqd, struct request *rq)
- 	rate /= divisor; /* smoothing constant alpha = 1/divisor */
- 
- 	bfq_log(bfqd,
--		"update_rate_reset: divisor %d tmp_peak_rate %llu tmp_rate %u",
-+		"divisor %d tmp_peak_rate %llu tmp_rate %u",
- 		divisor,
- 		((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT),
- 		(u32)((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT));
-@@ -2735,7 +2734,7 @@ static void bfq_update_peak_rate(struct bfq_data *bfqd, struct request *rq)
- 
- 	if (bfqd->peak_rate_samples == 0) { /* first dispatch */
- 		bfq_log(bfqd,
--		"update_peak_rate: goto reset, samples %d",
-+		"goto reset, samples %d",
- 				bfqd->peak_rate_samples) ;
- 		bfq_reset_rate_computation(bfqd, rq);
- 		goto update_last_values; /* will add one sample */
-@@ -2756,7 +2755,7 @@ static void bfq_update_peak_rate(struct bfq_data *bfqd, struct request *rq)
- 	if (now_ns - bfqd->last_dispatch > 100*NSEC_PER_MSEC &&
- 	    bfqd->rq_in_driver == 0) {
- 		bfq_log(bfqd,
--"update_peak_rate: jumping to updating&resetting delta_last %lluus samples %d",
-+"jumping to updating&resetting delta_last %lluus samples %d",
- 			(now_ns - bfqd->last_dispatch)>>10,
- 			bfqd->peak_rate_samples) ;
- 		goto update_rate_and_reset;
-@@ -2782,7 +2781,7 @@ static void bfq_update_peak_rate(struct bfq_data *bfqd, struct request *rq)
- 	bfqd->delta_from_first = now_ns - bfqd->first_dispatch;
- 
- 	bfq_log(bfqd,
--	"update_peak_rate: added samples %u/%u tot_sects %llu delta_first %lluus",
-+	"added samples %u/%u tot_sects %llu delta_first %lluus",
- 		bfqd->peak_rate_samples, bfqd->sequential_samples,
- 		bfqd->tot_sectors_dispatched,
- 		bfqd->delta_from_first>>10);
-@@ -2798,12 +2797,12 @@ static void bfq_update_peak_rate(struct bfq_data *bfqd, struct request *rq)
- 	bfqd->last_dispatch = now_ns;
- 
- 	bfq_log(bfqd,
--	"update_peak_rate: delta_first %lluus last_pos %llu peak_rate %llu",
-+	"delta_first %lluus last_pos %llu peak_rate %llu",
- 		(now_ns - bfqd->first_dispatch)>>10,
- 		(unsigned long long) bfqd->last_position,
- 		((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT));
- 	bfq_log(bfqd,
--	"update_peak_rate: samples at end %d", bfqd->peak_rate_samples);
-+	"samples at end %d", bfqd->peak_rate_samples);
- }
- 
- /*
-@@ -2900,11 +2899,11 @@ static void __bfq_bfqq_recalc_budget(struct bfq_data *bfqd,
- 	      */
- 		budget = 2 * min_budget;
- 
--	bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last budg %d, budg left %d",
-+	bfq_log_bfqq(bfqd, bfqq, "last budg %d, budg left %d",
- 		bfqq->entity.budget, bfq_bfqq_budget_left(bfqq));
--	bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last max_budg %d, min budg %d",
-+	bfq_log_bfqq(bfqd, bfqq, "last max_budg %d, min budg %d",
- 		budget, bfq_min_budget(bfqd));
--	bfq_log_bfqq(bfqd, bfqq, "recalc_budg: sync %d, seeky %d",
-+	bfq_log_bfqq(bfqd, bfqq, "sync %d, seeky %d",
- 		bfq_bfqq_sync(bfqq), BFQQ_SEEKY(bfqd->in_service_queue));
- 
- 	if (bfq_bfqq_sync(bfqq) && bfqq->wr_coeff == 1) {
-@@ -3106,7 +3105,7 @@ static bool bfq_bfqq_is_slow(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 		else /* charge at least one seek */
- 			*delta_ms = bfq_slice_idle / NSEC_PER_MSEC;
- 
--		bfq_log(bfqd, "bfq_bfqq_is_slow: too short %u", delta_usecs);
-+		bfq_log(bfqd, "too short %u", delta_usecs);
- 
- 		return slow;
- 	}
-@@ -3129,11 +3128,11 @@ static bool bfq_bfqq_is_slow(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 		 * peak rate.
- 		 */
- 		slow = bfqq->entity.service < bfqd->bfq_max_budget / 2;
--		bfq_log(bfqd, "bfq_bfqq_is_slow: relative rate %d/%d",
-+		bfq_log(bfqd, "relative rate %d/%d",
- 			bfqq->entity.service, bfqd->bfq_max_budget);
- 	}
- 
--	bfq_log_bfqq(bfqd, bfqq, "bfq_bfqq_is_slow: slow %d", slow);
-+	bfq_log_bfqq(bfqd, bfqq, "slow %d", slow);
- 
- 	return slow;
- }
-@@ -3235,7 +3234,7 @@ static unsigned long bfq_bfqq_softrt_next_start(struct bfq_data *bfqd,
- 						struct bfq_queue *bfqq)
- {
- 	bfq_log_bfqq(bfqd, bfqq,
--"softrt_next_start: service_blkg %lu soft_rate %u sects/sec interval %u",
-+"service_blkg %lu soft_rate %u sects/sec interval %u",
- 		     bfqq->service_from_backlogged,
- 		     bfqd->bfq_wr_max_softrt_rate,
- 		     jiffies_to_msecs(HZ * bfqq->service_from_backlogged /
-@@ -3414,7 +3413,7 @@ static bool bfq_bfqq_budget_timeout(struct bfq_queue *bfqq)
- static bool bfq_may_expire_for_budg_timeout(struct bfq_queue *bfqq)
- {
- 	bfq_log_bfqq(bfqq->bfqd, bfqq,
--		"may_budget_timeout: wait_request %d left %d timeout %d",
-+		"wait_request %d left %d timeout %d",
- 		bfq_bfqq_wait_request(bfqq),
- 			bfq_bfqq_budget_left(bfqq) >=  bfqq->entity.budget / 3,
- 		bfq_bfqq_budget_timeout(bfqq));
-@@ -3675,11 +3674,11 @@ static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq)
- 	 * either boosts the throughput (without issues), or is
- 	 * necessary to preserve service guarantees.
- 	 */
--	bfq_log_bfqq(bfqd, bfqq, "may_idle: sync %d idling_boosts_thr %d",
-+	bfq_log_bfqq(bfqd, bfqq, "sync %d idling_boosts_thr %d",
- 		     bfq_bfqq_sync(bfqq), idling_boosts_thr);
- 
- 	bfq_log_bfqq(bfqd, bfqq,
--		     "may_idle: wr_busy %d boosts %d IO-bound %d guar %d",
-+		     "wr_busy %d boosts %d IO-bound %d guar %d",
- 		     bfqd->wr_busy_queues,
- 		     idling_boosts_thr_without_issues,
- 		     bfq_bfqq_IO_bound(bfqq),
-@@ -3719,7 +3718,7 @@ static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd)
- 	if (!bfqq)
- 		goto new_queue;
- 
--	bfq_log_bfqq(bfqd, bfqq, "select_queue: already in-service queue");
-+	bfq_log_bfqq(bfqd, bfqq, "already in-service queue");
- 
- 	if (bfq_may_expire_for_budg_timeout(bfqq) &&
- 	    !hrtimer_active(&bfqd->idle_slice_timer) &&
-@@ -3797,14 +3796,14 @@ static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd)
- new_queue:
- 	bfqq = bfq_set_in_service_queue(bfqd);
- 	if (bfqq) {
--		bfq_log_bfqq(bfqd, bfqq, "select_queue: checking new queue");
-+		bfq_log_bfqq(bfqd, bfqq, "checking new queue");
- 		goto check_queue;
- 	}
- keep_queue:
- 	if (bfqq)
--		bfq_log_bfqq(bfqd, bfqq, "select_queue: returned this queue");
-+		bfq_log_bfqq(bfqd, bfqq, "returned this queue");
- 	else
--		bfq_log(bfqd, "select_queue: no queue returned");
-+		bfq_log(bfqd, "no queue returned");
- 
- 	return bfqq;
- }
-@@ -3857,8 +3856,7 @@ static void bfq_update_wr_data(struct bfq_data *bfqd, struct bfq_queue *bfqq)
- 			       /* see comments on max_service_from_wr */
- 			       bfq_bfqq_end_wr(bfqq);
- 			       bfq_log_bfqq(bfqd, bfqq,
--					       "[%s] too much service",
--					       __func__);
-+					       "too much service");
- 	       }
- 	}
- 	/*
-@@ -3987,7 +3985,7 @@ static int bfq_dispatch_requests(struct request_queue *q, int force)
- 	struct bfq_data *bfqd = q->elevator->elevator_data;
- 	struct bfq_queue *bfqq;
- 
--	bfq_log(bfqd, "dispatch requests: %d busy queues", bfqd->busy_queues);
-+	bfq_log(bfqd, "%d busy queues", bfqd->busy_queues);
- 
- 	if (bfqd->busy_queues == 0)
- 		return 0;
-@@ -4021,7 +4019,7 @@ static int bfq_dispatch_requests(struct request_queue *q, int force)
- 	if (!bfq_dispatch_request(bfqd, bfqq))
- 		return 0;
- 
--	bfq_log_bfqq(bfqd, bfqq, "dispatched %s request",
-+	bfq_log_bfqq(bfqd, bfqq, "%s request",
- 			bfq_bfqq_sync(bfqq) ? "sync" : "async");
- 
- 	BUG_ON(bfqq->next_rq == NULL &&
-@@ -4044,7 +4042,7 @@ static void bfq_put_queue(struct bfq_queue *bfqq)
- 
- 	BUG_ON(bfqq->ref <= 0);
- 
--	bfq_log_bfqq(bfqq->bfqd, bfqq, "put_queue: %p %d", bfqq, bfqq->ref);
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "%p %d", bfqq, bfqq->ref);
- 	bfqq->ref--;
- 	if (bfqq->ref)
- 		return;
-@@ -4086,7 +4084,7 @@ static void bfq_put_queue(struct bfq_queue *bfqq)
- 			bfqq->bfqd->burst_size--;
- 	}
- 
--	bfq_log_bfqq(bfqq->bfqd, bfqq, "put_queue: %p freed", bfqq);
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "%p freed", bfqq);
- 
- 	kmem_cache_free(bfq_pool, bfqq);
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
-@@ -4120,7 +4118,7 @@ static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
- 		bfq_schedule_dispatch(bfqd);
- 	}
- 
--	bfq_log_bfqq(bfqd, bfqq, "exit_bfqq: %p, %d", bfqq, bfqq->ref);
-+	bfq_log_bfqq(bfqd, bfqq, "%p, %d", bfqq, bfqq->ref);
- 
- 	bfq_put_cooperator(bfqq);
- 
-@@ -4200,7 +4198,7 @@ static void bfq_set_next_ioprio_data(struct bfq_queue *bfqq,
- 	bfqq->entity.new_weight = bfq_ioprio_to_weight(bfqq->new_ioprio);
- 	bfqq->entity.prio_changed = 1;
- 	bfq_log_bfqq(bfqq->bfqd, bfqq,
--		     "set_next_ioprio_data: bic_class %d prio %d class %d",
-+		     "bic_class %d prio %d class %d",
- 		     ioprio_class, bfqq->new_ioprio, bfqq->new_ioprio_class);
- }
- 
-@@ -4227,7 +4225,7 @@ static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio)
- 		bfqq = bfq_get_queue(bfqd, bio, BLK_RW_ASYNC, bic);
- 		bic_set_bfqq(bic, bfqq, false);
- 		bfq_log_bfqq(bfqd, bfqq,
--			     "check_ioprio_change: bfqq %p %d",
-+			     "bfqq %p %d",
- 			     bfqq, bfqq->ref);
- 	}
- 
-@@ -4362,14 +4360,14 @@ static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd,
- 			      * guarantee that this queue is not freed
- 			      * until its group goes away.
- 			      */
--		bfq_log_bfqq(bfqd, bfqq, "get_queue, bfqq not in async: %p, %d",
-+		bfq_log_bfqq(bfqd, bfqq, "bfqq not in async: %p, %d",
- 			     bfqq, bfqq->ref);
- 		*async_bfqq = bfqq;
- 	}
- 
- out:
- 	bfqq->ref++; /* get a process reference to this queue */
--	bfq_log_bfqq(bfqd, bfqq, "get_queue, at end: %p, %d", bfqq, bfqq->ref);
-+	bfq_log_bfqq(bfqd, bfqq, "at end: %p, %d", bfqq, bfqq->ref);
- 	rcu_read_unlock();
- 	return bfqq;
- }
-@@ -4428,7 +4426,7 @@ static void bfq_update_has_short_ttime(struct bfq_data *bfqd,
- 	     bic->ttime.ttime_mean > bfqd->bfq_slice_idle))
- 		has_short_ttime = false;
- 
--	bfq_log_bfqq(bfqd, bfqq, "update_has_short_ttime: has_short_ttime %d",
-+	bfq_log_bfqq(bfqd, bfqq, "has_short_ttime %d",
- 		has_short_ttime);
- 
- 	if (has_short_ttime)
-@@ -4454,7 +4452,7 @@ static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq,
- 	bfq_update_io_seektime(bfqd, bfqq, rq);
- 
- 	bfq_log_bfqq(bfqd, bfqq,
--		     "rq_enqueued: has_short_ttime=%d (seeky %d)",
-+		     "has_short_ttime=%d (seeky %d)",
- 		     bfq_bfqq_has_short_ttime(bfqq), BFQQ_SEEKY(bfqq));
- 
- 	bfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
-@@ -4629,7 +4627,7 @@ static void bfq_completed_request(struct request_queue *q, struct request *rq)
- 	 */
- 	delta_us = div_u64(now_ns - bfqd->last_completion, NSEC_PER_USEC);
- 
--	bfq_log(bfqd, "rq_completed: delta %uus/%luus max_size %u rate %llu/%llu",
-+	bfq_log(bfqd, "delta %uus/%luus max_size %u rate %llu/%llu",
- 		delta_us, BFQ_MIN_TT/NSEC_PER_USEC, bfqd->last_rq_max_size,
- 		delta_us > 0 ?
- 		(USEC_PER_SEC*
-@@ -4750,7 +4748,7 @@ static void bfq_put_request(struct request *rq)
- 		rq->elv.priv[0] = NULL;
- 		rq->elv.priv[1] = NULL;
- 
--		bfq_log_bfqq(bfqq->bfqd, bfqq, "put_request %p, %d",
-+		bfq_log_bfqq(bfqq->bfqd, bfqq, "%p, %d",
- 			     bfqq, bfqq->ref);
- 		bfq_put_queue(bfqq);
- 	}
-@@ -4816,7 +4814,7 @@ static int bfq_set_request(struct request_queue *q, struct request *rq,
- 		bic_set_bfqq(bic, bfqq, is_sync);
- 		if (split && is_sync) {
- 			bfq_log_bfqq(bfqd, bfqq,
--				     "set_request: was_in_list %d "
-+				     "was_in_list %d "
- 				     "was_in_large_burst %d "
- 				     "large burst in progress %d",
- 				     bic->was_in_burst_list,
-@@ -4826,12 +4824,12 @@ static int bfq_set_request(struct request_queue *q, struct request *rq,
- 			if ((bic->was_in_burst_list && bfqd->large_burst) ||
- 			    bic->saved_in_large_burst) {
- 				bfq_log_bfqq(bfqd, bfqq,
--					     "set_request: marking in "
-+					     "marking in "
- 					     "large burst");
- 				bfq_mark_bfqq_in_large_burst(bfqq);
- 			} else {
- 				bfq_log_bfqq(bfqd, bfqq,
--					     "set_request: clearing in "
-+					     "clearing in "
- 					     "large burst");
- 				bfq_clear_bfqq_in_large_burst(bfqq);
- 				if (bic->was_in_burst_list)
-@@ -4888,7 +4886,7 @@ static int bfq_set_request(struct request_queue *q, struct request *rq,
- 
- 	bfqq->allocated[rw]++;
- 	bfqq->ref++;
--	bfq_log_bfqq(bfqd, bfqq, "set_request: bfqq %p, %d", bfqq, bfqq->ref);
-+	bfq_log_bfqq(bfqd, bfqq, "bfqq %p, %d", bfqq, bfqq->ref);
- 
- 	rq->elv.priv[0] = bic;
- 	rq->elv.priv[1] = bfqq;
-@@ -4962,7 +4960,7 @@ static enum hrtimer_restart bfq_idle_slice_timer(struct hrtimer *timer)
- 	 * case we just expire a queue too early.
- 	 */
- 	if (bfqq) {
--		bfq_log_bfqq(bfqd, bfqq, "slice_timer expired");
-+		bfq_log_bfqq(bfqd, bfqq, "expired");
- 		bfq_clear_bfqq_wait_request(bfqq);
- 
- 		if (bfq_bfqq_budget_timeout(bfqq))
-@@ -5005,10 +5003,10 @@ static void __bfq_put_async_bfqq(struct bfq_data *bfqd,
- 	struct bfq_group *root_group = bfqd->root_group;
- 	struct bfq_queue *bfqq = *bfqq_ptr;
- 
--	bfq_log(bfqd, "put_async_bfqq: %p", bfqq);
-+	bfq_log(bfqd, "%p", bfqq);
- 	if (bfqq) {
- 		bfq_bfqq_move(bfqd, bfqq, root_group);
--		bfq_log_bfqq(bfqd, bfqq, "put_async_bfqq: putting %p, %d",
-+		bfq_log_bfqq(bfqd, bfqq, "putting %p, %d",
- 			     bfqq, bfqq->ref);
- 		bfq_put_queue(bfqq);
- 		*bfqq_ptr = NULL;
-diff --git a/block/bfq.h b/block/bfq.h
-index 0cd7a3f251a7..4d2fe7f77af1 100644
---- a/block/bfq.h
-+++ b/block/bfq.h
-@@ -698,37 +698,37 @@ static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
- 									\
- 	assert_spin_locked((bfqd)->queue->queue_lock);			\
- 	blkg_path(bfqg_to_blkg(bfqq_group(bfqq)), __pbuf, sizeof(__pbuf)); \
--	pr_crit("%s bfq%d%c %s " fmt "\n", 				\
-+	pr_crit("%s bfq%d%c %s [%s] " fmt "\n",				\
- 		checked_dev_name((bfqd)->queue->backing_dev_info->dev),	\
- 		(bfqq)->pid,						\
- 		bfq_bfqq_sync((bfqq)) ? 'S' : 'A',			\
--		__pbuf, ##args);					\
-+		__pbuf, __func__, ##args);				\
- } while (0)
- 
- #define bfq_log_bfqg(bfqd, bfqg, fmt, args...)	do {			\
- 	char __pbuf[128];						\
- 									\
- 	blkg_path(bfqg_to_blkg(bfqg), __pbuf, sizeof(__pbuf));		\
--	pr_crit("%s %s " fmt "\n",					\
-+	pr_crit("%s %s [%s] " fmt "\n",					\
- 	checked_dev_name((bfqd)->queue->backing_dev_info->dev),		\
--	__pbuf, ##args);						\
-+	__pbuf, __func__, ##args);					\
- } while (0)
- 
- #else /* BFQ_GROUP_IOSCHED_ENABLED */
- 
- #define bfq_log_bfqq(bfqd, bfqq, fmt, args...)				\
--	pr_crit("%s bfq%d%c " fmt "\n",					\
-+	pr_crit("%s bfq%d%c [%s] " fmt "\n",				\
- 		checked_dev_name((bfqd)->queue->backing_dev_info->dev),	\
- 		(bfqq)->pid, bfq_bfqq_sync((bfqq)) ? 'S' : 'A',		\
--		##args)
-+		__func__, ##args)
- #define bfq_log_bfqg(bfqd, bfqg, fmt, args...)		do {} while (0)
- 
- #endif /* BFQ_GROUP_IOSCHED_ENABLED */
- 
- #define bfq_log(bfqd, fmt, args...) \
--	pr_crit("%s bfq " fmt "\n",					\
-+	pr_crit("%s bfq [%s] " fmt "\n",				\
- 		checked_dev_name((bfqd)->queue->backing_dev_info->dev),	\
--		##args)
-+		__func__, ##args)
- 
- #else /* CONFIG_BFQ_REDIRECT_TO_CONSOLE */
- 
-@@ -755,31 +755,32 @@ static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
- 									\
- 	assert_spin_locked((bfqd)->queue->queue_lock);			\
- 	blkg_path(bfqg_to_blkg(bfqq_group(bfqq)), __pbuf, sizeof(__pbuf)); \
--	blk_add_trace_msg((bfqd)->queue, "bfq%d%c %s " fmt, \
-+	blk_add_trace_msg((bfqd)->queue, "bfq%d%c %s [%s] " fmt, \
- 			  (bfqq)->pid,			  \
- 			  bfq_bfqq_sync((bfqq)) ? 'S' : 'A',	\
--			  __pbuf, ##args);				\
-+			  __pbuf, __func__, ##args);			\
- } while (0)
- 
- #define bfq_log_bfqg(bfqd, bfqg, fmt, args...)	do {			\
- 	char __pbuf[128];						\
- 									\
- 	blkg_path(bfqg_to_blkg(bfqg), __pbuf, sizeof(__pbuf));		\
--	blk_add_trace_msg((bfqd)->queue, "%s " fmt, __pbuf, ##args);	\
-+	blk_add_trace_msg((bfqd)->queue, "%s [%s] " fmt, __pbuf, \
-+	__func__, ##args);	\
- } while (0)
- 
- #else /* BFQ_GROUP_IOSCHED_ENABLED */
- 
- #define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	\
--	blk_add_trace_msg((bfqd)->queue, "bfq%d%c " fmt, (bfqq)->pid,	\
-+	blk_add_trace_msg((bfqd)->queue, "bfq%d%c [%s] " fmt, (bfqq)->pid, \
- 			bfq_bfqq_sync((bfqq)) ? 'S' : 'A',		\
--				##args)
-+				__func__, ##args)
- #define bfq_log_bfqg(bfqd, bfqg, fmt, args...)		do {} while (0)
- 
- #endif /* BFQ_GROUP_IOSCHED_ENABLED */
- 
- #define bfq_log(bfqd, fmt, args...) \
--	blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args)
-+	blk_add_trace_msg((bfqd)->queue, "bfq [%s] " fmt, __func__, ##args)
- 
- #endif /* CONFIG_BLK_DEV_IO_TRACE */
- #endif /* CONFIG_BFQ_REDIRECT_TO_CONSOLE */
-@@ -928,7 +929,7 @@ bfq_entity_service_tree(struct bfq_entity *entity)
- 
- 	if (bfqq)
- 		bfq_log_bfqq(bfqq->bfqd, bfqq,
--			     "entity_service_tree %p %d",
-+			     "%p %d",
- 			     sched_data->service_tree + idx, idx);
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	else {
-@@ -936,7 +937,7 @@ bfq_entity_service_tree(struct bfq_entity *entity)
- 			container_of(entity, struct bfq_group, entity);
- 
- 		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
--			     "entity_service_tree %p %d",
-+			     "%p %d",
- 			     sched_data->service_tree + idx, idx);
- 	}
- #endif
-
-From 673a457e8a54d1c4b66e61b1a50956ba0b8c6a60 Mon Sep 17 00:00:00 2001
-From: Davide Paganelli <paga.david@gmail.com>
-Date: Thu, 8 Feb 2018 11:49:58 +0100
-Subject: [PATCH 19/23] block, bfq-mq, bfq-sq: make bfq_bfqq_expire print
- expiration reason
-
-Improve readability of the log messages related to the expiration
-reasons of the function bfq_bfqq_expire.
-Change the printing of the number that represents the reason for
-expiration with an actual textual description of the reason.
-
-Signed-off-by: Davide Paganelli <paga.david@gmail.com>
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-mq-iosched.c | 10 ++++++++--
- block/bfq-sq-iosched.c | 10 ++++++++--
- 2 files changed, 16 insertions(+), 4 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index edc93b6af186..9268dd47a4e5 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -133,6 +133,12 @@ static const int bfq_timeout = (HZ / 8);
-  */
- static const unsigned long bfq_merge_time_limit = HZ/10;
- 
-+#define MAX_LENGTH_REASON_NAME 25
-+
-+static const char reason_name[][MAX_LENGTH_REASON_NAME] = {"TOO_IDLE",
-+"BUDGET_TIMEOUT", "BUDGET_EXHAUSTED", "NO_MORE_REQUESTS",
-+"PREEMPTED"};
-+
- static struct kmem_cache *bfq_pool;
- 
- /* Below this threshold (in ns), we consider thinktime immediate. */
-@@ -3553,8 +3559,8 @@ static void bfq_bfqq_expire(struct bfq_data *bfqd,
- 	}
- 
- 	bfq_log_bfqq(bfqd, bfqq,
--		"expire (%d, slow %d, num_disp %d, short_ttime %d, weight %d)",
--		     reason, slow, bfqq->dispatched,
-+		"expire (%s, slow %d, num_disp %d, short_ttime %d, weight %d)",
-+		     reason_name[reason], slow, bfqq->dispatched,
- 		     bfq_bfqq_has_short_ttime(bfqq), entity->weight);
- 
- 	/*
-diff --git a/block/bfq-sq-iosched.c b/block/bfq-sq-iosched.c
-index e49e8ac882b3..f95deaab49a1 100644
---- a/block/bfq-sq-iosched.c
-+++ b/block/bfq-sq-iosched.c
-@@ -127,6 +127,12 @@ static const int bfq_timeout = (HZ / 8);
-  */
- static const unsigned long bfq_merge_time_limit = HZ/10;
- 
-+#define MAX_LENGTH_REASON_NAME 25
-+
-+static const char reason_name[][MAX_LENGTH_REASON_NAME] = {"TOO_IDLE",
-+"BUDGET_TIMEOUT", "BUDGET_EXHAUSTED", "NO_MORE_REQUESTS",
-+"PREEMPTED"};
-+
- static struct kmem_cache *bfq_pool;
- 
- /* Below this threshold (in ns), we consider thinktime immediate. */
-@@ -3366,8 +3372,8 @@ static void bfq_bfqq_expire(struct bfq_data *bfqd,
- 	}
- 
- 	bfq_log_bfqq(bfqd, bfqq,
--		"expire (%d, slow %d, num_disp %d, short_ttime %d, weight %d)",
--		     reason, slow, bfqq->dispatched,
-+		"expire (%s, slow %d, num_disp %d, short_ttime %d, weight %d)",
-+		     reason_name[reason], slow, bfqq->dispatched,
- 		     bfq_bfqq_has_short_ttime(bfqq), entity->weight);
- 
- 	/*
-
-From 62e80623fbb58367c3f667dab22fea0804001f3b Mon Sep 17 00:00:00 2001
-From: Melzani Alessandro <melzani.alessandro@gmail.com>
-Date: Mon, 26 Feb 2018 22:21:59 +0100
-Subject: [PATCH 20/23] bfq-mq: port of "block, bfq: remove batches of
- confusing ifdefs"
-
-Commit a33801e8b473 ("block, bfq: move debug blkio stats behind
-CONFIG_DEBUG_BLK_CGROUP") introduced two batches of confusing ifdefs:
-one reported in [1], plus a similar one in another function. This
-commit removes both batches, in the way suggested in [1].
-
-[1] https://www.spinics.net/lists/linux-block/msg20043.html
-
-Fixes: a33801e8b473 ("block, bfq: move debug blkio stats behind CONFIG_DEBUG_BLK_CGROUP")
-
-Signed-off-by: Alessandro Melzani <melzani.alessandro@gmail.com>
----
- block/bfq-mq-iosched.c | 128 ++++++++++++++++++++++++++++---------------------
- 1 file changed, 73 insertions(+), 55 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 9268dd47a4e5..5a211620f316 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -4256,35 +4256,17 @@ static struct request *__bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
- 	return rq;
- }
- 
--static struct request *bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
--{
--	struct bfq_data *bfqd = hctx->queue->elevator->elevator_data;
--	struct request *rq;
--#if defined(BFQ_GROUP_IOSCHED_ENABLED) &&  defined(CONFIG_DEBUG_BLK_CGROUP)
--	struct bfq_queue *in_serv_queue, *bfqq;
--	bool waiting_rq, idle_timer_disabled;
--#endif
- 
--	spin_lock_irq(&bfqd->lock);
--
--#if defined(BFQ_GROUP_IOSCHED_ENABLED) &&  defined(CONFIG_DEBUG_BLK_CGROUP)
--	in_serv_queue = bfqd->in_service_queue;
--	waiting_rq = in_serv_queue && bfq_bfqq_wait_request(in_serv_queue);
--
--	rq = __bfq_dispatch_request(hctx);
--
--	idle_timer_disabled =
--		waiting_rq && !bfq_bfqq_wait_request(in_serv_queue);
--
--#else
--	rq = __bfq_dispatch_request(hctx);
--#endif
--	spin_unlock_irq(&bfqd->lock);
-+#if defined(BFQ_GROUP_IOSCHED_ENABLED) && defined(CONFIG_DEBUG_BLK_CGROUP)
-+static void bfq_update_dispatch_stats(struct request_queue *q,
-+				      struct request *rq,
-+				      struct bfq_queue *in_serv_queue,
-+				      bool idle_timer_disabled)
-+{
-+	struct bfq_queue *bfqq = rq ? RQ_BFQQ(rq) : NULL;
- 
--#if defined(BFQ_GROUP_IOSCHED_ENABLED) &&  defined(CONFIG_DEBUG_BLK_CGROUP)
--	bfqq = rq ? RQ_BFQQ(rq) : NULL;
- 	if (!idle_timer_disabled && !bfqq)
--		return rq;
-+		return;
- 
- 	/*
- 	 * rq and bfqq are guaranteed to exist until this function
-@@ -4299,7 +4281,7 @@ static struct request *bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
- 	 * In addition, the following queue lock guarantees that
- 	 * bfqq_group(bfqq) exists as well.
- 	 */
--	spin_lock_irq(hctx->queue->queue_lock);
-+	spin_lock_irq(q->queue_lock);
- 	if (idle_timer_disabled)
- 		/*
- 		 * Since the idle timer has been disabled,
-@@ -4318,8 +4300,35 @@ static struct request *bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
- 		bfqg_stats_set_start_empty_time(bfqg);
- 		bfqg_stats_update_io_remove(bfqg, rq->cmd_flags);
- 	}
--	spin_unlock_irq(hctx->queue->queue_lock);
-+	spin_unlock_irq(q->queue_lock);
-+}
-+#else
-+static inline void bfq_update_dispatch_stats(struct request_queue *q,
-+					     struct request *rq,
-+					     struct bfq_queue *in_serv_queue,
-+					     bool idle_timer_disabled) {}
- #endif
-+static struct request *bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
-+{
-+	struct bfq_data *bfqd = hctx->queue->elevator->elevator_data;
-+	struct request *rq;
-+	struct bfq_queue *in_serv_queue;
-+	bool waiting_rq, idle_timer_disabled;
-+
-+	spin_lock_irq(&bfqd->lock);
-+
-+	in_serv_queue = bfqd->in_service_queue;
-+	waiting_rq = in_serv_queue && bfq_bfqq_wait_request(in_serv_queue);
-+
-+	rq = __bfq_dispatch_request(hctx);
-+
-+	idle_timer_disabled =
-+		waiting_rq && !bfq_bfqq_wait_request(in_serv_queue);
-+
-+	spin_unlock_irq(&bfqd->lock);
-+
-+	bfq_update_dispatch_stats(hctx->queue, rq, in_serv_queue,
-+				  idle_timer_disabled);
- 
- 	return rq;
- }
-@@ -4881,6 +4890,38 @@ static bool __bfq_insert_request(struct bfq_data *bfqd, struct request *rq)
- 	return idle_timer_disabled;
- }
- 
-+#if defined(BFQ_GROUP_IOSCHED_ENABLED) && defined(CONFIG_DEBUG_BLK_CGROUP)
-+static void bfq_update_insert_stats(struct request_queue *q,
-+				    struct bfq_queue *bfqq,
-+				    bool idle_timer_disabled,
-+				    unsigned int cmd_flags)
-+{
-+	if (!bfqq)
-+		return;
-+
-+	/*
-+	 * bfqq still exists, because it can disappear only after
-+	 * either it is merged with another queue, or the process it
-+	 * is associated with exits. But both actions must be taken by
-+	 * the same process currently executing this flow of
-+	 * instructions.
-+	 *
-+	 * In addition, the following queue lock guarantees that
-+	 * bfqq_group(bfqq) exists as well.
-+	 */
-+	spin_lock_irq(q->queue_lock);
-+	bfqg_stats_update_io_add(bfqq_group(bfqq), bfqq, cmd_flags);
-+	if (idle_timer_disabled)
-+		bfqg_stats_update_idle_time(bfqq_group(bfqq));
-+	spin_unlock_irq(q->queue_lock);
-+}
-+#else
-+static inline void bfq_update_insert_stats(struct request_queue *q,
-+					   struct bfq_queue *bfqq,
-+					   bool idle_timer_disabled,
-+					   unsigned int cmd_flags) {}
-+#endif
-+
- static void bfq_prepare_request(struct request *rq, struct bio *bio);
- 
- static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
-@@ -4889,10 +4930,8 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
- 	struct request_queue *q = hctx->queue;
- 	struct bfq_data *bfqd = q->elevator->elevator_data;
- 	struct bfq_queue *bfqq = RQ_BFQQ(rq);
--#if defined(BFQ_GROUP_IOSCHED_ENABLED) &&  defined(CONFIG_DEBUG_BLK_CGROUP)
- 	bool idle_timer_disabled = false;
- 	unsigned int cmd_flags;
--#endif
- 
- 	spin_lock_irq(&bfqd->lock);
- 	if (blk_mq_sched_try_insert_merge(q, rq)) {
-@@ -4938,7 +4977,6 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
- 			bfqq = RQ_BFQQ(rq);
- 		}
- 
--#if defined(BFQ_GROUP_IOSCHED_ENABLED) &&  defined(CONFIG_DEBUG_BLK_CGROUP)
- 		idle_timer_disabled = __bfq_insert_request(bfqd, rq);
- 		/*
- 		 * Update bfqq, because, if a queue merge has occurred
-@@ -4946,9 +4984,6 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
- 		 * redirected into a new queue.
- 		 */
- 		bfqq = RQ_BFQQ(rq);
--#else
--		__bfq_insert_request(bfqd, rq);
--#endif
- 
- 		if (rq_mergeable(rq)) {
- 			elv_rqhash_add(q, rq);
-@@ -4956,34 +4991,17 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
- 				q->last_merge = rq;
- 		}
- 	}
--#if defined(BFQ_GROUP_IOSCHED_ENABLED) &&  defined(CONFIG_DEBUG_BLK_CGROUP)
-+
- 	/*
- 	 * Cache cmd_flags before releasing scheduler lock, because rq
- 	 * may disappear afterwards (for example, because of a request
- 	 * merge).
- 	 */
- 	cmd_flags = rq->cmd_flags;
--#endif
-+
- 	spin_unlock_irq(&bfqd->lock);
--#if defined(BFQ_GROUP_IOSCHED_ENABLED) &&  defined(CONFIG_DEBUG_BLK_CGROUP)
--	if (!bfqq)
--		return;
--	/*
--	 * bfqq still exists, because it can disappear only after
--	 * either it is merged with another queue, or the process it
--	 * is associated with exits. But both actions must be taken by
--	 * the same process currently executing this flow of
--	 * instruction.
--	 *
--	 * In addition, the following queue lock guarantees that
--	 * bfqq_group(bfqq) exists as well.
--	 */
--	spin_lock_irq(q->queue_lock);
--	bfqg_stats_update_io_add(bfqq_group(bfqq), bfqq, cmd_flags);
--	if (idle_timer_disabled)
--		bfqg_stats_update_idle_time(bfqq_group(bfqq));
--	spin_unlock_irq(q->queue_lock);
--#endif
-+	bfq_update_insert_stats(q, bfqq, idle_timer_disabled,
-+				cmd_flags);
- }
- 
- static void bfq_insert_requests(struct blk_mq_hw_ctx *hctx,
-
-From 0d0d05632872b226f4fae5e56af8736a4c24bf57 Mon Sep 17 00:00:00 2001
-From: Melzani Alessandro <melzani.alessandro@gmail.com>
-Date: Mon, 26 Feb 2018 22:43:30 +0100
-Subject: [PATCH 21/23] bfq-sq, bfq-mq: port of "bfq: Use icq_to_bic()
- consistently"
-
-Some code uses icq_to_bic() to convert an io_cq pointer to a
-bfq_io_cq pointer while other code uses a direct cast. Convert
-the code that uses a direct cast such that it uses icq_to_bic().
-
-Signed-off-by: Alessandro Melzani <melzani.alessandro@gmail.com>
----
- block/bfq-mq-iosched.c | 2 +-
- block/bfq-sq-iosched.c | 2 +-
- 2 files changed, 2 insertions(+), 2 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 5a211620f316..7b1269558c47 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -272,7 +272,7 @@ static const unsigned long max_service_from_wr = 120000;
- #define BFQ_SERVICE_TREE_INIT	((struct bfq_service_tree)		\
- 				{ RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 })
- 
--#define RQ_BIC(rq)		((struct bfq_io_cq *) (rq)->elv.priv[0])
-+#define RQ_BIC(rq)		icq_to_bic((rq)->elv.priv[0])
- #define RQ_BFQQ(rq)		((rq)->elv.priv[1])
- 
- /**
-diff --git a/block/bfq-sq-iosched.c b/block/bfq-sq-iosched.c
-index f95deaab49a1..c4aff8d55fc4 100644
---- a/block/bfq-sq-iosched.c
-+++ b/block/bfq-sq-iosched.c
-@@ -266,7 +266,7 @@ static const unsigned long max_service_from_wr = 120000;
- #define BFQ_SERVICE_TREE_INIT	((struct bfq_service_tree)		\
- 				{ RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 })
- 
--#define RQ_BIC(rq)		((struct bfq_io_cq *) (rq)->elv.priv[0])
-+#define RQ_BIC(rq)		icq_to_bic((rq)->elv.priv[0])
- #define RQ_BFQQ(rq)		((rq)->elv.priv[1])
- 
- static void bfq_schedule_dispatch(struct bfq_data *bfqd);
-
-From 4cb5de6add7d6ad0d25d73cb95dc871305db1522 Mon Sep 17 00:00:00 2001
-From: Melzani Alessandro <melzani.alessandro@gmail.com>
-Date: Mon, 26 Feb 2018 22:59:30 +0100
-Subject: [PATCH 22/23] bfq-sq, bfq-mq: port of "block, bfq: fix error handle
- in bfq_init"
-
-if elv_register fail, bfq_pool should be free.
-
-Signed-off-by: Alessandro Melzani <melzani.alessandro@gmail.com>
----
- block/bfq-mq-iosched.c | 4 +++-
- block/bfq-sq-iosched.c | 4 +++-
- 2 files changed, 6 insertions(+), 2 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 7b1269558c47..964e88c2ce59 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -6129,7 +6129,7 @@ static int __init bfq_init(void)
- 
- 	ret = elv_register(&iosched_bfq_mq);
- 	if (ret)
--		goto err_pol_unreg;
-+		goto slab_kill;
- 
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	strcat(msg, " (with cgroups support)");
-@@ -6138,6 +6138,8 @@ static int __init bfq_init(void)
- 
- 	return 0;
- 
-+slab_kill:
-+	bfq_slab_kill();
- err_pol_unreg:
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	blkcg_policy_unregister(&blkcg_policy_bfq);
-diff --git a/block/bfq-sq-iosched.c b/block/bfq-sq-iosched.c
-index c4aff8d55fc4..7f0cf1f01ffc 100644
---- a/block/bfq-sq-iosched.c
-+++ b/block/bfq-sq-iosched.c
-@@ -5590,7 +5590,7 @@ static int __init bfq_init(void)
- 
- 	ret = elv_register(&iosched_bfq);
- 	if (ret)
--		goto err_pol_unreg;
-+		goto slab_kill;
- 
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	strcat(msg, " (with cgroups support)");
-@@ -5599,6 +5599,8 @@ static int __init bfq_init(void)
- 
- 	return 0;
- 
-+slab_kill:
-+	bfq_slab_kill();
- err_pol_unreg:
- #ifdef BFQ_GROUP_IOSCHED_ENABLED
- 	blkcg_policy_unregister(&blkcg_policy_bfq);
-
-From 1f77c173aaa87ffb22c9f062a6449245d14311e4 Mon Sep 17 00:00:00 2001
-From: Paolo Valente <paolo.valente@linaro.org>
-Date: Wed, 4 Apr 2018 11:28:16 +0200
-Subject: [PATCH 23/23] block, bfq-sq, bfq-mq: lower-bound the estimated peak
- rate to 1
-
-If a storage device handled by BFQ happens to be slower than 7.5 KB/s
-for a certain amount of time (in the order of a second), then the
-estimated peak rate of the device, maintained in BFQ, becomes equal to
-0. The reason is the limited precision with which the rate is
-represented (details on the range of representable values in the
-comments introduced by this commit). This leads to a division-by-zero
-error where the estimated peak rate is used as divisor. Such a type of
-failure has been reported in [1].
-
-This commit addresses this issue by:
-1. Lower-bounding the estimated peak rate to 1
-2. Adding and improving comments on the range of rates representable
-
-[1] https://www.spinics.net/lists/kernel/msg2739205.html
-
-Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
-Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
----
- block/bfq-mq-iosched.c | 25 ++++++++++++++++++++++++-
- block/bfq-mq.h         |  7 ++++++-
- block/bfq-sq-iosched.c | 25 ++++++++++++++++++++++++-
- block/bfq.h            |  7 ++++++-
- 4 files changed, 60 insertions(+), 4 deletions(-)
-
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-index 964e88c2ce59..03efd90c5d20 100644
---- a/block/bfq-mq-iosched.c
-+++ b/block/bfq-mq-iosched.c
-@@ -160,7 +160,20 @@ static struct kmem_cache *bfq_pool;
- /* Target observation time interval for a peak-rate update (ns) */
- #define BFQ_RATE_REF_INTERVAL	NSEC_PER_SEC
- 
--/* Shift used for peak rate fixed precision calculations. */
-+/*
-+ * Shift used for peak-rate fixed precision calculations.
-+ * With
-+ * - the current shift: 16 positions
-+ * - the current type used to store rate: u32
-+ * - the current unit of measure for rate: [sectors/usec], or, more precisely,
-+ *   [(sectors/usec) / 2^BFQ_RATE_SHIFT] to take into account the shift,
-+ * the range of rates that can be stored is
-+ * [1 / 2^BFQ_RATE_SHIFT, 2^(32 - BFQ_RATE_SHIFT)] sectors/usec =
-+ * [1 / 2^16, 2^16] sectors/usec = [15e-6, 65536] sectors/usec =
-+ * [15, 65G] sectors/sec
-+ * Which, assuming a sector size of 512B, corresponds to a range of
-+ * [7.5K, 33T] B/sec
-+ */
- #define BFQ_RATE_SHIFT		16
- 
- /*
-@@ -2881,6 +2894,16 @@ static void bfq_update_rate_reset(struct bfq_data *bfqd, struct request *rq)
- 	BUG_ON(bfqd->peak_rate > 20<<BFQ_RATE_SHIFT);
- 
- 	bfqd->peak_rate += rate;
-+
-+	/*
-+	 * For a very slow device, bfqd->peak_rate can reach 0 (see
-+	 * the minimum representable values reported in the comments
-+	 * on BFQ_RATE_SHIFT). Push to 1 if this happens, to avoid
-+	 * divisions by zero where bfqd->peak_rate is used as a
-+	 * divisor.
-+	 */
-+	bfqd->peak_rate = max_t(u32, 1, bfqd->peak_rate);
-+
- 	update_thr_responsiveness_params(bfqd);
- 	BUG_ON(bfqd->peak_rate > 20<<BFQ_RATE_SHIFT);
- 
-diff --git a/block/bfq-mq.h b/block/bfq-mq.h
-index e2ae11bf8f76..4a54e5076863 100644
---- a/block/bfq-mq.h
-+++ b/block/bfq-mq.h
-@@ -490,7 +490,12 @@ struct bfq_data {
- 	u32 last_rq_max_size;
- 	/* time elapsed from first dispatch in current observ. interval (us) */
- 	u64 delta_from_first;
--	/* current estimate of device peak rate */
-+	/*
-+	 * Current estimate of the device peak rate, measured in
-+	 * [(sectors/usec) / 2^BFQ_RATE_SHIFT]. The left-shift by
-+	 * BFQ_RATE_SHIFT is performed to increase precision in
-+	 * fixed-point calculations.
-+	 */
- 	u32 peak_rate;
- 
- 	/* maximum budget allotted to a bfq_queue before rescheduling */
-diff --git a/block/bfq-sq-iosched.c b/block/bfq-sq-iosched.c
-index 7f0cf1f01ffc..e96213865fc2 100644
---- a/block/bfq-sq-iosched.c
-+++ b/block/bfq-sq-iosched.c
-@@ -154,7 +154,20 @@ static struct kmem_cache *bfq_pool;
- /* Target observation time interval for a peak-rate update (ns) */
- #define BFQ_RATE_REF_INTERVAL	NSEC_PER_SEC
- 
--/* Shift used for peak rate fixed precision calculations. */
-+/*
-+ * Shift used for peak-rate fixed precision calculations.
-+ * With
-+ * - the current shift: 16 positions
-+ * - the current type used to store rate: u32
-+ * - the current unit of measure for rate: [sectors/usec], or, more precisely,
-+ *   [(sectors/usec) / 2^BFQ_RATE_SHIFT] to take into account the shift,
-+ * the range of rates that can be stored is
-+ * [1 / 2^BFQ_RATE_SHIFT, 2^(32 - BFQ_RATE_SHIFT)] sectors/usec =
-+ * [1 / 2^16, 2^16] sectors/usec = [15e-6, 65536] sectors/usec =
-+ * [15, 65G] sectors/sec
-+ * Which, assuming a sector size of 512B, corresponds to a range of
-+ * [7.5K, 33T] B/sec
-+ */
- #define BFQ_RATE_SHIFT		16
- 
- /*
-@@ -2695,6 +2708,16 @@ static void bfq_update_rate_reset(struct bfq_data *bfqd, struct request *rq)
- 	BUG_ON(bfqd->peak_rate > 20<<BFQ_RATE_SHIFT);
- 
- 	bfqd->peak_rate += rate;
-+
-+	/*
-+	 * For a very slow device, bfqd->peak_rate can reach 0 (see
-+	 * the minimum representable values reported in the comments
-+	 * on BFQ_RATE_SHIFT). Push to 1 if this happens, to avoid
-+	 * divisions by zero where bfqd->peak_rate is used as a
-+	 * divisor.
-+	 */
-+	bfqd->peak_rate = max_t(u32, 1, bfqd->peak_rate);
-+
- 	update_thr_responsiveness_params(bfqd);
- 	BUG_ON(bfqd->peak_rate > 20<<BFQ_RATE_SHIFT);
- 
-diff --git a/block/bfq.h b/block/bfq.h
-index 4d2fe7f77af1..a25e76c906d9 100644
---- a/block/bfq.h
-+++ b/block/bfq.h
-@@ -498,7 +498,12 @@ struct bfq_data {
- 	u32 last_rq_max_size;
- 	/* time elapsed from first dispatch in current observ. interval (us) */
- 	u64 delta_from_first;
--	/* current estimate of device peak rate */
-+	/*
-+	 * Current estimate of the device peak rate, measured in
-+	 * [(sectors/usec) / 2^BFQ_RATE_SHIFT]. The left-shift by
-+	 * BFQ_RATE_SHIFT is performed to increase precision in
-+	 * fixed-point calculations.
-+	 */
- 	u32 peak_rate;
- 
- 	/* maximum budget allotted to a bfq_queue before rescheduling */
diff --git a/sys-kernel/linux-image-redcore-lts/files/4.14-redcore-lts-amd64.config b/sys-kernel/linux-image-redcore-lts/files/4.14-amd64.config
index 23e35863..307b0bd9 100644
--- a/sys-kernel/linux-image-redcore-lts/files/4.14-redcore-lts-amd64.config
+++ b/sys-kernel/linux-image-redcore-lts/files/4.14-amd64.config
@@ -1,6 +1,6 @@
 #
 # Automatically generated file; DO NOT EDIT.
-# Linux/x86 4.14.90-redcore-lts Kernel Configuration
+# Linux/x86 4.14.95-redcore-lts-r1 Kernel Configuration
 #
 CONFIG_64BIT=y
 CONFIG_X86_64=y
@@ -432,15 +432,10 @@ CONFIG_IOSCHED_NOOP=y
 CONFIG_IOSCHED_DEADLINE=y
 CONFIG_IOSCHED_CFQ=y
 CONFIG_CFQ_GROUP_IOSCHED=y
-CONFIG_IOSCHED_BFQ_SQ=y
-CONFIG_BFQ_SQ_GROUP_IOSCHED=y
 # CONFIG_DEFAULT_DEADLINE is not set
-# CONFIG_DEFAULT_CFQ is not set
-CONFIG_DEFAULT_BFQ_SQ=y
+CONFIG_DEFAULT_CFQ=y
 # CONFIG_DEFAULT_NOOP is not set
-CONFIG_DEFAULT_IOSCHED="bfq-sq"
-CONFIG_MQ_IOSCHED_BFQ=y
-CONFIG_MQ_BFQ_GROUP_IOSCHED=y
+CONFIG_DEFAULT_IOSCHED="cfq"
 CONFIG_MQ_IOSCHED_DEADLINE=y
 # CONFIG_MQ_IOSCHED_KYBER is not set
 CONFIG_IOSCHED_BFQ=y
diff --git a/sys-kernel/linux-image-redcore-lts/files/4.19-redcore-lts-amd64.config b/sys-kernel/linux-image-redcore-lts/files/4.19-amd64.config
index c5bedf65..f0565a81 100644
--- a/sys-kernel/linux-image-redcore-lts/files/4.19-redcore-lts-amd64.config
+++ b/sys-kernel/linux-image-redcore-lts/files/4.19-amd64.config
@@ -1,6 +1,6 @@
 #
 # Automatically generated file; DO NOT EDIT.
-# Linux/x86 4.19.20-redcore-lts Kernel Configuration
+# Linux/x86 4.19.20-redcore-lts-r1 Kernel Configuration
 #
 
 #
@@ -937,15 +937,10 @@ CONFIG_IOSCHED_NOOP=y
 CONFIG_IOSCHED_DEADLINE=y
 CONFIG_IOSCHED_CFQ=y
 CONFIG_CFQ_GROUP_IOSCHED=y
-CONFIG_IOSCHED_BFQ_SQ=y
-CONFIG_BFQ_SQ_GROUP_IOSCHED=y
 # CONFIG_DEFAULT_DEADLINE is not set
-# CONFIG_DEFAULT_CFQ is not set
-CONFIG_DEFAULT_BFQ_SQ=y
+CONFIG_DEFAULT_CFQ=y
 # CONFIG_DEFAULT_NOOP is not set
-CONFIG_DEFAULT_IOSCHED="bfq-sq"
-CONFIG_MQ_IOSCHED_BFQ=y
-CONFIG_MQ_BFQ_GROUP_IOSCHED=y
+CONFIG_DEFAULT_IOSCHED="cfq"
 CONFIG_MQ_IOSCHED_DEADLINE=y
 # CONFIG_MQ_IOSCHED_KYBER is not set
 CONFIG_IOSCHED_BFQ=y
@@ -7564,7 +7559,7 @@ CONFIG_GREYBUS_SDIO=m
 CONFIG_GREYBUS_SPI=m
 CONFIG_GREYBUS_UART=m
 CONFIG_GREYBUS_USB=m
-# CONFIG_DRM_VBOXVIDEO is not set
+CONFIG_DRM_VBOXVIDEO=m
 CONFIG_PI433=m
 CONFIG_MTK_MMC=m
 # CONFIG_MTK_AEE_KDUMP is not set
diff --git a/sys-kernel/linux-image-redcore-lts/files/4.19-bfq-sq-mq-v9r1-2K190204-rc1.patch b/sys-kernel/linux-image-redcore-lts/files/4.19-bfq-sq-mq-v9r1-2K190204-rc1.patch
deleted file mode 100644
index 039c8fcd..00000000
--- a/sys-kernel/linux-image-redcore-lts/files/4.19-bfq-sq-mq-v9r1-2K190204-rc1.patch
+++ /dev/null
@@ -1,18511 +0,0 @@
-diff --git a/Documentation/block/bfq-iosched.txt b/Documentation/block/bfq-iosched.txt
-index 8d8d8f06cab2..41d0200944f1 100644
---- a/Documentation/block/bfq-iosched.txt
-+++ b/Documentation/block/bfq-iosched.txt
-@@ -1,3 +1,6 @@
-+[ THIS TREE CONTAINS ALSO THE DEV VERSION OF BFQ.
-+  DETAILS AT THE END OF THIS DOCUMENT. ]
-+
- BFQ (Budget Fair Queueing)
- ==========================
- 
-@@ -11,6 +14,15 @@ controllers), BFQ's main features are:
-   groups (switching back to time distribution when needed to keep
-   throughput high).
- 
-+If bfq-mq patches have been applied, then the following three
-+instances of BFQ are available (otherwise only the first instance):
-+- bfq: mainline version of BFQ, for blk-mq
-+- bfq-mq: development version of BFQ for blk-mq; this version contains
-+   also all latest features and fixes not yet landed in mainline, plus many
-+   safety checks
-+- bfq-sq: BFQ for legacy blk; also this version contains latest features
-+   and fixes, as well as safety checks
-+
- In its default configuration, BFQ privileges latency over
- throughput. So, when needed for achieving a lower latency, BFQ builds
- schedules that may lead to a lower throughput. If your main or only
-@@ -22,27 +34,42 @@ latency and throughput, or on how to maximize throughput.
- 
- BFQ has a non-null overhead, which limits the maximum IOPS that a CPU
- can process for a device scheduled with BFQ. To give an idea of the
--limits on slow or average CPUs, here are, first, the limits of BFQ for
--three different CPUs, on, respectively, an average laptop, an old
--desktop, and a cheap embedded system, in case full hierarchical
--support is enabled (i.e., CONFIG_BFQ_GROUP_IOSCHED is set), but
-+limits on slow or average CPUs, here are, first, the limits of bfq-mq
-+and bfq for three different CPUs, on, respectively, an average laptop,
-+an old desktop, and a cheap embedded system, in case full hierarchical
-+support is enabled (i.e., CONFIG_MQ_BFQ_GROUP_IOSCHED is set for
-+bfq-mq, or CONFIG_BFQ_GROUP_IOSCHED is set for bfq), but
- CONFIG_DEBUG_BLK_CGROUP is not set (Section 4-2):
- - Intel i7-4850HQ: 400 KIOPS
- - AMD A8-3850: 250 KIOPS
- - ARM CortexTM-A53 Octa-core: 80 KIOPS
- 
--If CONFIG_DEBUG_BLK_CGROUP is set (and of course full hierarchical
--support is enabled), then the sustainable throughput with BFQ
--decreases, because all blkio.bfq* statistics are created and updated
--(Section 4-2). For BFQ, this leads to the following maximum
--sustainable throughputs, on the same systems as above:
-+As for bfq-sq, it cannot reach the above IOPS, because of the
-+inherent, lower parallelism of legacy blk and of the components within
-+it (including bfq-sq itself). In particular, results with
-+CONFIG_DEBUG_BLK_CGROUP unset are rather fluctuating. The limits
-+reported below for the case CONFIG_DEBUG_BLK_CGROUP set will however
-+provide a lower bound to the limits of bfq-sq.
-+
-+Turning back to bfq-mq and bfq, If CONFIG_DEBUG_BLK_CGROUP is set (and
-+of course full hierarchical support is enabled), then the sustainable
-+throughput with bfq-mq and bfq decreases, because all blkio.bfq*
-+statistics are created and updated (Section 4-2).  For bfq-mq and bfq,
-+this leads to the following maximum sustainable throughputs, on the
-+same systems as above:
- - Intel i7-4850HQ: 310 KIOPS
- - AMD A8-3850: 200 KIOPS
- - ARM CortexTM-A53 Octa-core: 56 KIOPS
- 
--BFQ works for multi-queue devices too.
-+Finally, if CONFIG_DEBUG_BLK_CGROUP is set (and full hierarchical
-+support is enabled), then bfq-sq exhibits the following limits:
-+- Intel i7-4850HQ: 250 KIOPS
-+- AMD A8-3850: 170 KIOPS
-+- ARM CortexTM-A53 Octa-core: 45 KIOPS
- 
--The table of contents follow. Impatients can just jump to Section 3.
-+BFQ works for multi-queue devices too (bfq and bfq-mq instances).
-+
-+The table of contents follows. Impatients can just jump to Section 3.
- 
- CONTENTS
- 
-@@ -509,25 +536,27 @@ To get proportional sharing of bandwidth with BFQ for a given device,
- BFQ must of course be the active scheduler for that device.
- 
- Within each group directory, the names of the files associated with
--BFQ-specific cgroup parameters and stats begin with the "bfq."
--prefix. So, with cgroups-v1 or cgroups-v2, the full prefix for
--BFQ-specific files is "blkio.bfq." or "io.bfq." For example, the group
--parameter to set the weight of a group with BFQ is blkio.bfq.weight
-+BFQ-specific cgroup parameters and stats begin with the "bfq.",
-+"bfq-sq." or "bfq-mq." prefix, depending on which instance of bfq you
-+want to use. So, with cgroups-v1 or cgroups-v2, the full prefix for
-+BFQ-specific files is "blkio.bfqX." or "io.bfqX.", where X can be ""
-+(i.e., null string), "-sq" or "-mq". For example, the group parameter
-+to set the weight of a group with the mainline BFQ is blkio.bfq.weight
- or io.bfq.weight.
- 
- As for cgroups-v1 (blkio controller), the exact set of stat files
--created, and kept up-to-date by bfq, depends on whether
--CONFIG_DEBUG_BLK_CGROUP is set. If it is set, then bfq creates all
-+created, and kept up-to-date by bfq*, depends on whether
-+CONFIG_DEBUG_BLK_CGROUP is set. If it is set, then bfq* creates all
- the stat files documented in
- Documentation/cgroup-v1/blkio-controller.txt. If, instead,
--CONFIG_DEBUG_BLK_CGROUP is not set, then bfq creates only the files
--blkio.bfq.io_service_bytes
--blkio.bfq.io_service_bytes_recursive
--blkio.bfq.io_serviced
--blkio.bfq.io_serviced_recursive
-+CONFIG_DEBUG_BLK_CGROUP is not set, then bfq* creates only the files
-+blkio.bfq*.io_service_bytes
-+blkio.bfq*.io_service_bytes_recursive
-+blkio.bfq*.io_serviced
-+blkio.bfq*.io_serviced_recursive
- 
- The value of CONFIG_DEBUG_BLK_CGROUP greatly influences the maximum
--throughput sustainable with bfq, because updating the blkio.bfq.*
-+throughput sustainable with bfq*, because updating the blkio.bfq*
- stats is rather costly, especially for some of the stats enabled by
- CONFIG_DEBUG_BLK_CGROUP.
- 
-@@ -536,7 +565,7 @@ Parameters to set
- 
- For each group, there is only the following parameter to set.
- 
--weight (namely blkio.bfq.weight or io.bfq-weight): the weight of the
-+weight (namely blkio.bfqX.weight or io.bfqX.weight): the weight of the
- group inside its parent. Available values: 1..10000 (default 100). The
- linear mapping between ioprio and weights, described at the beginning
- of the tunable section, is still valid, but all weights higher than
-@@ -559,3 +588,55 @@ applications. Unset this tunable if you need/want to control weights.
-     Slightly extended version:
-     http://algogroup.unimore.it/people/paolo/disk_sched/bfq-v1-suite-
- 							results.pdf
-+
-+----------------------------------------------------------------------
-+
-+DETAILS ON THE DEV VERSIONS IN THIS TREE
-+
-+The dev version of BFQ is available for both the legacy and the
-+multi-queue block layers, as two additional I/O schedulers, named,
-+respectively, bfq-sq-iosched and bfq-mq-iosched (the latter is
-+available if also the changes introducing bfq-mq-iosched have been
-+applied). In particular, this tree contains the dev version of bfq for
-+Linux mainline 4.19.0, and has been obtained from the dev version for
-+Linux 4.18.0. Rebasing from 4.18 to 4.19 involved two manual
-+interventions.
-+
-+First, some conflicts had to be resolved, as follows:
-+
-+---------------------------------------------------------------
-+
-+diff --cc Makefile
-+index 7727c1bf6fa5,69fa5c0310d8..c7cbdf0ad594
-+--- a/Makefile
-++++ b/Makefile
-+@@@ -1,9 -1,9 +1,9 @@@
-+  # SPDX-License-Identifier: GPL-2.0
-+  VERSION = 4
-+- PATCHLEVEL = 18
-++ PATCHLEVEL = 19
-+  SUBLEVEL = 0
-+ -EXTRAVERSION =
-+ +EXTRAVERSION = -bfq-mq
-+- NAME = Merciless Moray
-++ NAME = "People's Front"
-+
-+  # *DOCUMENTATION*
-+  # To see a list of typical targets execute "make help"
-+diff --cc include/linux/blkdev.h
-+index 897c63322bd7,6980014357d4..8c4568ea6884
-+--- a/include/linux/blkdev.h
-++++ b/include/linux/blkdev.h
-+@@@ -56,7 -54,7 +54,7 @@@ struct blk_stat_callback
-+   * Maximum number of blkcg policies allowed to be registered concurrently.
-+   * Defined here to simplify include dependency.
-+   */
-+--#define BLKCG_MAX_POLS                5
-+++#define BLKCG_MAX_POLS                7
-+
-+  typedef void (rq_end_io_fn)(struct request *, blk_status_t);
-+
-+---------------------------------------------------------------
-+
-+Second, the following port commit had to be made:
-+port commit "block: use ktime_get_ns() instead of sched_clock() for cfq and bfq"
-diff --git a/arch/x86/configs/x86_64_defconfig b/arch/x86/configs/x86_64_defconfig
-index e32fc1f274d8..94cb28eb20ba 100644
---- a/arch/x86/configs/x86_64_defconfig
-+++ b/arch/x86/configs/x86_64_defconfig
-@@ -12,6 +12,11 @@ CONFIG_NO_HZ=y
- CONFIG_HIGH_RES_TIMERS=y
- CONFIG_LOG_BUF_SHIFT=18
- CONFIG_CGROUPS=y
-+CONFIG_BLK_CGROUP=y
-+CONFIG_IOSCHED_BFQ_SQ=y
-+CONFIG_BFQ_SQ_GROUP_IOSCHED=y
-+CONFIG_MQ_IOSCHED_BFQ=y
-+CONFIG_MQ_BFQ_GROUP_IOSCHED=y
- CONFIG_CGROUP_FREEZER=y
- CONFIG_CPUSETS=y
- CONFIG_CGROUP_CPUACCT=y
-diff --git a/block/Kconfig.iosched b/block/Kconfig.iosched
-index a4a8914bf7a4..299a6861fb90 100644
---- a/block/Kconfig.iosched
-+++ b/block/Kconfig.iosched
-@@ -40,6 +40,26 @@ config CFQ_GROUP_IOSCHED
- 	---help---
- 	  Enable group IO scheduling in CFQ.
- 
-+config IOSCHED_BFQ_SQ
-+	tristate "BFQ-SQ I/O scheduler"
-+	default n
-+	---help---
-+	The BFQ-SQ I/O scheduler (for legacy blk: SQ stands for
-+	SingleQueue) distributes bandwidth among all processes
-+	according to their weights, regardless of the device
-+	parameters and with any workload. It also guarantees a low
-+	latency to interactive and soft real-time applications.
-+	Details in Documentation/block/bfq-iosched.txt
-+
-+config BFQ_SQ_GROUP_IOSCHED
-+	bool "BFQ-SQ hierarchical scheduling support"
-+	depends on IOSCHED_BFQ_SQ && BLK_CGROUP
-+	default n
-+	---help---
-+
-+	Enable hierarchical scheduling in BFQ-SQ, using the blkio
-+	(cgroups-v1) or io (cgroups-v2) controller.
-+
- choice
- 
- 	prompt "Default I/O scheduler"
-@@ -54,6 +74,16 @@ choice
- 	config DEFAULT_CFQ
- 		bool "CFQ" if IOSCHED_CFQ=y
- 
-+	config DEFAULT_BFQ_SQ
-+		bool "BFQ-SQ" if IOSCHED_BFQ_SQ=y
-+		help
-+		  Selects BFQ-SQ as the default I/O scheduler which will be
-+		  used by default for all block devices.
-+		  The BFQ-SQ I/O scheduler aims at distributing the bandwidth
-+		  as desired, independently of the disk parameters and with
-+		  any workload. It also tries to guarantee low latency to
-+		  interactive and soft real-time applications.
-+
- 	config DEFAULT_NOOP
- 		bool "No-op"
- 
-@@ -63,8 +93,28 @@ config DEFAULT_IOSCHED
- 	string
- 	default "deadline" if DEFAULT_DEADLINE
- 	default "cfq" if DEFAULT_CFQ
-+	default "bfq-sq" if DEFAULT_BFQ_SQ
- 	default "noop" if DEFAULT_NOOP
- 
-+config MQ_IOSCHED_BFQ
-+	tristate "BFQ-MQ I/O Scheduler"
-+	default y
-+	---help---
-+	BFQ I/O scheduler for BLK-MQ. BFQ-MQ distributes bandwidth
-+	among all processes according to their weights, regardless of
-+	the device parameters and with any workload. It also
-+	guarantees a low latency to interactive and soft real-time
-+	applications.  Details in Documentation/block/bfq-iosched.txt
-+
-+config MQ_BFQ_GROUP_IOSCHED
-+	bool "BFQ-MQ hierarchical scheduling support"
-+	depends on MQ_IOSCHED_BFQ && BLK_CGROUP
-+	default n
-+	---help---
-+
-+	Enable hierarchical scheduling in BFQ-MQ, using the blkio
-+	(cgroups-v1) or io (cgroups-v2) controller.
-+
- config MQ_IOSCHED_DEADLINE
- 	tristate "MQ deadline I/O scheduler"
- 	default y
-diff --git a/block/Makefile b/block/Makefile
-index 572b33f32c07..1dd6ffdc2fee 100644
---- a/block/Makefile
-+++ b/block/Makefile
-@@ -25,6 +25,8 @@ obj-$(CONFIG_MQ_IOSCHED_DEADLINE)	+= mq-deadline.o
- obj-$(CONFIG_MQ_IOSCHED_KYBER)	+= kyber-iosched.o
- bfq-y				:= bfq-iosched.o bfq-wf2q.o bfq-cgroup.o
- obj-$(CONFIG_IOSCHED_BFQ)	+= bfq.o
-+obj-$(CONFIG_IOSCHED_BFQ_SQ)	+= bfq-sq-iosched.o
-+obj-$(CONFIG_MQ_IOSCHED_BFQ)	+= bfq-mq-iosched.o
- 
- obj-$(CONFIG_BLOCK_COMPAT)	+= compat_ioctl.o
- obj-$(CONFIG_BLK_CMDLINE_PARSER)	+= cmdline-parser.o
-diff --git a/block/bfq-cgroup-included.c b/block/bfq-cgroup-included.c
-new file mode 100644
-index 000000000000..15459e50cd6a
---- /dev/null
-+++ b/block/bfq-cgroup-included.c
-@@ -0,0 +1,1359 @@
-+/*
-+ * BFQ: CGROUPS support.
-+ *
-+ * Based on ideas and code from CFQ:
-+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
-+ *
-+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
-+ *		      Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2016 Paolo Valente <paolo.valente@linaro.org>
-+ *
-+ * Licensed under the GPL-2 as detailed in the accompanying COPYING.BFQ
-+ * file.
-+ */
-+
-+#if defined(BFQ_GROUP_IOSCHED_ENABLED) && defined(CONFIG_DEBUG_BLK_CGROUP)
-+
-+/* bfqg stats flags */
-+enum bfqg_stats_flags {
-+	BFQG_stats_waiting = 0,
-+	BFQG_stats_idling,
-+	BFQG_stats_empty,
-+};
-+
-+#define BFQG_FLAG_FNS(name)						\
-+static void bfqg_stats_mark_##name(struct bfqg_stats *stats)	\
-+{									\
-+	stats->flags |= (1 << BFQG_stats_##name);			\
-+}									\
-+static void bfqg_stats_clear_##name(struct bfqg_stats *stats)	\
-+{									\
-+	stats->flags &= ~(1 << BFQG_stats_##name);			\
-+}									\
-+static int bfqg_stats_##name(struct bfqg_stats *stats)		\
-+{									\
-+	return (stats->flags & (1 << BFQG_stats_##name)) != 0;		\
-+}									\
-+
-+BFQG_FLAG_FNS(waiting)
-+BFQG_FLAG_FNS(idling)
-+BFQG_FLAG_FNS(empty)
-+#undef BFQG_FLAG_FNS
-+
-+#ifdef BFQ_MQ
-+/* This should be called with the scheduler lock held. */
-+#else
-+/* This should be called with the queue_lock held. */
-+#endif
-+static void bfqg_stats_update_group_wait_time(struct bfqg_stats *stats)
-+{
-+	u64 now;
-+
-+	if (!bfqg_stats_waiting(stats))
-+		return;
-+
-+	now = ktime_get_ns();
-+	if (now > stats->start_group_wait_time)
-+		blkg_stat_add(&stats->group_wait_time,
-+			      now - stats->start_group_wait_time);
-+	bfqg_stats_clear_waiting(stats);
-+}
-+
-+#ifdef BFQ_MQ
-+/* This should be called with the scheduler lock held. */
-+#else
-+/* This should be called with the queue_lock held. */
-+#endif
-+static void bfqg_stats_set_start_group_wait_time(struct bfq_group *bfqg,
-+						 struct bfq_group *curr_bfqg)
-+{
-+	struct bfqg_stats *stats = &bfqg->stats;
-+
-+	if (bfqg_stats_waiting(stats))
-+		return;
-+	if (bfqg == curr_bfqg)
-+		return;
-+	stats->start_group_wait_time = ktime_get_ns();
-+	bfqg_stats_mark_waiting(stats);
-+}
-+
-+#ifdef BFQ_MQ
-+/* This should be called with the scheduler lock held. */
-+#else
-+/* This should be called with the queue_lock held. */
-+#endif
-+static void bfqg_stats_end_empty_time(struct bfqg_stats *stats)
-+{
-+	u64 now;
-+
-+	if (!bfqg_stats_empty(stats))
-+		return;
-+
-+	now = ktime_get_ns();
-+	if (now > stats->start_empty_time)
-+		blkg_stat_add(&stats->empty_time,
-+			      now - stats->start_empty_time);
-+	bfqg_stats_clear_empty(stats);
-+}
-+
-+static void bfqg_stats_update_dequeue(struct bfq_group *bfqg)
-+{
-+	blkg_stat_add(&bfqg->stats.dequeue, 1);
-+}
-+
-+static void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg)
-+{
-+	struct bfqg_stats *stats = &bfqg->stats;
-+
-+	if (blkg_rwstat_total(&stats->queued))
-+		return;
-+
-+	/*
-+	 * group is already marked empty. This can happen if bfqq got new
-+	 * request in parent group and moved to this group while being added
-+	 * to service tree. Just ignore the event and move on.
-+	 */
-+	if (bfqg_stats_empty(stats))
-+		return;
-+
-+	stats->start_empty_time = ktime_get_ns();
-+	bfqg_stats_mark_empty(stats);
-+}
-+
-+static void bfqg_stats_update_idle_time(struct bfq_group *bfqg)
-+{
-+	struct bfqg_stats *stats = &bfqg->stats;
-+
-+	if (bfqg_stats_idling(stats)) {
-+		u64 now = ktime_get_ns();
-+
-+		if (now > stats->start_idle_time)
-+			blkg_stat_add(&stats->idle_time,
-+				      now - stats->start_idle_time);
-+		bfqg_stats_clear_idling(stats);
-+	}
-+}
-+
-+static void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg)
-+{
-+	struct bfqg_stats *stats = &bfqg->stats;
-+
-+	stats->start_idle_time = ktime_get_ns();
-+	bfqg_stats_mark_idling(stats);
-+}
-+
-+static void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg)
-+{
-+	struct bfqg_stats *stats = &bfqg->stats;
-+
-+	blkg_stat_add(&stats->avg_queue_size_sum,
-+		      blkg_rwstat_total(&stats->queued));
-+	blkg_stat_add(&stats->avg_queue_size_samples, 1);
-+	bfqg_stats_update_group_wait_time(stats);
-+}
-+
-+static void bfqg_stats_update_io_add(struct bfq_group *bfqg,
-+				     struct bfq_queue *bfqq,
-+				     unsigned int op)
-+{
-+	blkg_rwstat_add(&bfqg->stats.queued, op, 1);
-+	bfqg_stats_end_empty_time(&bfqg->stats);
-+	if (!(bfqq == ((struct bfq_data *)bfqg->bfqd)->in_service_queue))
-+		bfqg_stats_set_start_group_wait_time(bfqg, bfqq_group(bfqq));
-+}
-+
-+static void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op)
-+{
-+	blkg_rwstat_add(&bfqg->stats.queued, op, -1);
-+}
-+
-+static void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op)
-+{
-+	blkg_rwstat_add(&bfqg->stats.merged, op, 1);
-+}
-+
-+static void bfqg_stats_update_completion(struct bfq_group *bfqg,
-+					 u64 start_time_ns,
-+					 u64 io_start_time_ns,
-+					 unsigned int op)
-+{
-+	struct bfqg_stats *stats = &bfqg->stats;
-+	u64 now = ktime_get_ns();
-+
-+	if (now > io_start_time_ns)
-+		blkg_rwstat_add(&stats->service_time, op,
-+				now - io_start_time_ns);
-+	if (io_start_time_ns > start_time_ns)
-+		blkg_rwstat_add(&stats->wait_time, op,
-+				io_start_time_ns - start_time_ns);
-+}
-+
-+#else /* BFQ_GROUP_IOSCHED_ENABLED && CONFIG_DEBUG_BLK_CGROUP */
-+
-+static inline void bfqg_stats_update_io_add(struct bfq_group *bfqg,
-+			struct bfq_queue *bfqq, unsigned int op) { }
-+static inline void
-+bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op) { }
-+static inline void
-+bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op) { }
-+static inline void bfqg_stats_update_completion(struct bfq_group *bfqg,
-+						u64 start_time_ns,
-+						u64 io_start_time_ns,
-+						unsigned int op) { }
-+static inline void
-+bfqg_stats_set_start_group_wait_time(struct bfq_group *bfqg,
-+		struct bfq_group *curr_bfqg) { }
-+static inline void bfqg_stats_end_empty_time(struct bfqg_stats *stats) { }
-+static inline void bfqg_stats_update_dequeue(struct bfq_group *bfqg) { }
-+static inline void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg) { }
-+static inline void bfqg_stats_update_idle_time(struct bfq_group *bfqg) { }
-+static inline void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg) { }
-+static inline void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg) { }
-+
-+#endif /* BFQ_GROUP_IOSCHED_ENABLED && CONFIG_DEBUG_BLK_CGROUP */
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+static struct blkcg_policy blkcg_policy_bfq;
-+
-+/*
-+ * blk-cgroup policy-related handlers
-+ * The following functions help in converting between blk-cgroup
-+ * internal structures and BFQ-specific structures.
-+ */
-+
-+static struct bfq_group *pd_to_bfqg(struct blkg_policy_data *pd)
-+{
-+	return pd ? container_of(pd, struct bfq_group, pd) : NULL;
-+}
-+
-+static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg)
-+{
-+	return pd_to_blkg(&bfqg->pd);
-+}
-+
-+static struct bfq_group *blkg_to_bfqg(struct blkcg_gq *blkg)
-+{
-+	struct blkg_policy_data *pd = blkg_to_pd(blkg, &blkcg_policy_bfq);
-+
-+	return pd_to_bfqg(pd);
-+}
-+
-+/*
-+ * bfq_group handlers
-+ * The following functions help in navigating the bfq_group hierarchy
-+ * by allowing to find the parent of a bfq_group or the bfq_group
-+ * associated to a bfq_queue.
-+ */
-+
-+static struct bfq_group *bfqg_parent(struct bfq_group *bfqg)
-+{
-+	struct blkcg_gq *pblkg = bfqg_to_blkg(bfqg)->parent;
-+
-+	return pblkg ? blkg_to_bfqg(pblkg) : NULL;
-+}
-+
-+static struct bfq_group *bfqq_group(struct bfq_queue *bfqq)
-+{
-+	struct bfq_entity *group_entity = bfqq->entity.parent;
-+
-+	return group_entity ? container_of(group_entity, struct bfq_group,
-+					   entity) :
-+			      bfqq->bfqd->root_group;
-+}
-+
-+/*
-+ * The following two functions handle get and put of a bfq_group by
-+ * wrapping the related blk-cgroup hooks.
-+ */
-+
-+static void bfqg_get(struct bfq_group *bfqg)
-+{
-+#ifdef BFQ_MQ
-+	bfqg->ref++;
-+#else
-+	blkg_get(bfqg_to_blkg(bfqg));
-+#endif
-+}
-+
-+static void bfqg_put(struct bfq_group *bfqg)
-+{
-+#ifdef BFQ_MQ
-+	bfqg->ref--;
-+
-+	BUG_ON(bfqg->ref < 0);
-+	if (bfqg->ref == 0)
-+		kfree(bfqg);
-+#else
-+	blkg_put(bfqg_to_blkg(bfqg));
-+#endif
-+}
-+
-+#ifdef BFQ_MQ
-+static void bfqg_and_blkg_get(struct bfq_group *bfqg)
-+{
-+	/* see comments in bfq_bic_update_cgroup for why refcounting bfqg */
-+	bfqg_get(bfqg);
-+
-+	blkg_get(bfqg_to_blkg(bfqg));
-+}
-+
-+static void bfqg_and_blkg_put(struct bfq_group *bfqg)
-+{
-+	blkg_put(bfqg_to_blkg(bfqg));
-+
-+	bfqg_put(bfqg);
-+}
-+#endif
-+
-+/* @stats = 0 */
-+static void bfqg_stats_reset(struct bfqg_stats *stats)
-+{
-+#ifdef CONFIG_DEBUG_BLK_CGROUP
-+	/* queued stats shouldn't be cleared */
-+	blkg_rwstat_reset(&stats->merged);
-+	blkg_rwstat_reset(&stats->service_time);
-+	blkg_rwstat_reset(&stats->wait_time);
-+	blkg_stat_reset(&stats->time);
-+	blkg_stat_reset(&stats->avg_queue_size_sum);
-+	blkg_stat_reset(&stats->avg_queue_size_samples);
-+	blkg_stat_reset(&stats->dequeue);
-+	blkg_stat_reset(&stats->group_wait_time);
-+	blkg_stat_reset(&stats->idle_time);
-+	blkg_stat_reset(&stats->empty_time);
-+#endif
-+}
-+
-+/* @to += @from */
-+static void bfqg_stats_add_aux(struct bfqg_stats *to, struct bfqg_stats *from)
-+{
-+	if (!to || !from)
-+		return;
-+
-+#ifdef CONFIG_DEBUG_BLK_CGROUP
-+	/* queued stats shouldn't be cleared */
-+	blkg_rwstat_add_aux(&to->merged, &from->merged);
-+	blkg_rwstat_add_aux(&to->service_time, &from->service_time);
-+	blkg_rwstat_add_aux(&to->wait_time, &from->wait_time);
-+	blkg_stat_add_aux(&from->time, &from->time);
-+	blkg_stat_add_aux(&to->avg_queue_size_sum, &from->avg_queue_size_sum);
-+	blkg_stat_add_aux(&to->avg_queue_size_samples,
-+			  &from->avg_queue_size_samples);
-+	blkg_stat_add_aux(&to->dequeue, &from->dequeue);
-+	blkg_stat_add_aux(&to->group_wait_time, &from->group_wait_time);
-+	blkg_stat_add_aux(&to->idle_time, &from->idle_time);
-+	blkg_stat_add_aux(&to->empty_time, &from->empty_time);
-+#endif
-+}
-+
-+/*
-+ * Transfer @bfqg's stats to its parent's dead_stats so that the ancestors'
-+ * recursive stats can still account for the amount used by this bfqg after
-+ * it's gone.
-+ */
-+static void bfqg_stats_xfer_dead(struct bfq_group *bfqg)
-+{
-+	struct bfq_group *parent;
-+
-+	if (!bfqg) /* root_group */
-+		return;
-+
-+	parent = bfqg_parent(bfqg);
-+
-+	lockdep_assert_held(bfqg_to_blkg(bfqg)->q->queue_lock);
-+
-+	if (unlikely(!parent))
-+		return;
-+
-+	bfqg_stats_add_aux(&parent->stats, &bfqg->stats);
-+	bfqg_stats_reset(&bfqg->stats);
-+}
-+
-+static void bfq_init_entity(struct bfq_entity *entity,
-+			    struct bfq_group *bfqg)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+
-+	entity->weight = entity->new_weight;
-+	entity->orig_weight = entity->new_weight;
-+	if (bfqq) {
-+		bfqq->ioprio = bfqq->new_ioprio;
-+		bfqq->ioprio_class = bfqq->new_ioprio_class;
-+#ifdef BFQ_MQ
-+		/*
-+		 * Make sure that bfqg and its associated blkg do not
-+		 * disappear before entity.
-+		 */
-+		bfq_log_bfqq(bfqq->bfqd, bfqq, "getting bfqg %p and blkg\n",
-+		bfqg);
-+
-+		bfqg_and_blkg_get(bfqg);
-+#else
-+		bfqg_get(bfqg);
-+#endif
-+	}
-+	entity->parent = bfqg->my_entity; /* NULL for root group */
-+	entity->sched_data = &bfqg->sched_data;
-+}
-+
-+static void bfqg_stats_exit(struct bfqg_stats *stats)
-+{
-+#ifdef CONFIG_DEBUG_BLK_CGROUP
-+	blkg_rwstat_exit(&stats->merged);
-+	blkg_rwstat_exit(&stats->service_time);
-+	blkg_rwstat_exit(&stats->wait_time);
-+	blkg_rwstat_exit(&stats->queued);
-+	blkg_stat_exit(&stats->time);
-+	blkg_stat_exit(&stats->avg_queue_size_sum);
-+	blkg_stat_exit(&stats->avg_queue_size_samples);
-+	blkg_stat_exit(&stats->dequeue);
-+	blkg_stat_exit(&stats->group_wait_time);
-+	blkg_stat_exit(&stats->idle_time);
-+	blkg_stat_exit(&stats->empty_time);
-+#endif
-+}
-+
-+static int bfqg_stats_init(struct bfqg_stats *stats, gfp_t gfp)
-+{
-+#ifdef CONFIG_DEBUG_BLK_CGROUP
-+	if (blkg_rwstat_init(&stats->merged, gfp) ||
-+	    blkg_rwstat_init(&stats->service_time, gfp) ||
-+	    blkg_rwstat_init(&stats->wait_time, gfp) ||
-+	    blkg_rwstat_init(&stats->queued, gfp) ||
-+	    blkg_stat_init(&stats->time, gfp) ||
-+	    blkg_stat_init(&stats->avg_queue_size_sum, gfp) ||
-+	    blkg_stat_init(&stats->avg_queue_size_samples, gfp) ||
-+	    blkg_stat_init(&stats->dequeue, gfp) ||
-+	    blkg_stat_init(&stats->group_wait_time, gfp) ||
-+	    blkg_stat_init(&stats->idle_time, gfp) ||
-+	    blkg_stat_init(&stats->empty_time, gfp)) {
-+		bfqg_stats_exit(stats);
-+		return -ENOMEM;
-+	}
-+#endif
-+
-+	return 0;
-+}
-+
-+static struct bfq_group_data *cpd_to_bfqgd(struct blkcg_policy_data *cpd)
-+{
-+	return cpd ? container_of(cpd, struct bfq_group_data, pd) : NULL;
-+}
-+
-+static struct bfq_group_data *blkcg_to_bfqgd(struct blkcg *blkcg)
-+{
-+	return cpd_to_bfqgd(blkcg_to_cpd(blkcg, &blkcg_policy_bfq));
-+}
-+
-+static struct blkcg_policy_data *bfq_cpd_alloc(gfp_t gfp)
-+{
-+	struct bfq_group_data *bgd;
-+
-+	bgd = kzalloc(sizeof(*bgd), gfp);
-+	if (!bgd)
-+		return NULL;
-+	return &bgd->pd;
-+}
-+
-+static void bfq_cpd_init(struct blkcg_policy_data *cpd)
-+{
-+	struct bfq_group_data *d = cpd_to_bfqgd(cpd);
-+
-+	d->weight = cgroup_subsys_on_dfl(io_cgrp_subsys) ?
-+		CGROUP_WEIGHT_DFL : BFQ_WEIGHT_LEGACY_DFL;
-+}
-+
-+static void bfq_cpd_free(struct blkcg_policy_data *cpd)
-+{
-+	kfree(cpd_to_bfqgd(cpd));
-+}
-+
-+static struct blkg_policy_data *bfq_pd_alloc(gfp_t gfp, int node)
-+{
-+	struct bfq_group *bfqg;
-+
-+	bfqg = kzalloc_node(sizeof(*bfqg), gfp, node);
-+	if (!bfqg)
-+		return NULL;
-+
-+	if (bfqg_stats_init(&bfqg->stats, gfp)) {
-+		kfree(bfqg);
-+		return NULL;
-+	}
-+#ifdef BFQ_MQ
-+	/* see comments in bfq_bic_update_cgroup for why refcounting */
-+	bfqg_get(bfqg);
-+#endif
-+	return &bfqg->pd;
-+}
-+
-+static void bfq_pd_init(struct blkg_policy_data *pd)
-+{
-+	struct blkcg_gq *blkg;
-+	struct bfq_group *bfqg;
-+	struct bfq_data *bfqd;
-+	struct bfq_entity *entity;
-+	struct bfq_group_data *d;
-+
-+	blkg = pd_to_blkg(pd);
-+	BUG_ON(!blkg);
-+	bfqg = blkg_to_bfqg(blkg);
-+	bfqd = blkg->q->elevator->elevator_data;
-+	BUG_ON(bfqg == bfqd->root_group);
-+	entity = &bfqg->entity;
-+	d = blkcg_to_bfqgd(blkg->blkcg);
-+
-+	entity->orig_weight = entity->weight = entity->new_weight = d->weight;
-+	entity->my_sched_data = &bfqg->sched_data;
-+	bfqg->my_entity = entity; /*
-+				   * the root_group's will be set to NULL
-+				   * in bfq_init_queue()
-+				   */
-+	bfqg->bfqd = bfqd;
-+	bfqg->active_entities = 0;
-+	bfqg->rq_pos_tree = RB_ROOT;
-+}
-+
-+static void bfq_pd_free(struct blkg_policy_data *pd)
-+{
-+	struct bfq_group *bfqg = pd_to_bfqg(pd);
-+
-+	bfqg_stats_exit(&bfqg->stats);
-+#ifdef BFQ_MQ
-+	bfqg_put(bfqg);
-+#else
-+	kfree(bfqg);
-+#endif
-+}
-+
-+static void bfq_pd_reset_stats(struct blkg_policy_data *pd)
-+{
-+	struct bfq_group *bfqg = pd_to_bfqg(pd);
-+
-+	bfqg_stats_reset(&bfqg->stats);
-+}
-+
-+static void bfq_group_set_parent(struct bfq_group *bfqg,
-+					struct bfq_group *parent)
-+{
-+	struct bfq_entity *entity;
-+
-+	BUG_ON(!parent);
-+	BUG_ON(!bfqg);
-+	BUG_ON(bfqg == parent);
-+
-+	entity = &bfqg->entity;
-+	entity->parent = parent->my_entity;
-+	entity->sched_data = &parent->sched_data;
-+}
-+
-+static struct bfq_group *bfq_lookup_bfqg(struct bfq_data *bfqd,
-+					 struct blkcg *blkcg)
-+{
-+	struct blkcg_gq *blkg;
-+
-+	blkg = blkg_lookup(blkcg, bfqd->queue);
-+	if (likely(blkg))
-+		return blkg_to_bfqg(blkg);
-+	return NULL;
-+}
-+
-+static struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd,
-+					    struct blkcg *blkcg)
-+{
-+	struct bfq_group *bfqg, *parent;
-+	struct bfq_entity *entity;
-+
-+	bfqg = bfq_lookup_bfqg(bfqd, blkcg);
-+
-+	if (unlikely(!bfqg))
-+		return NULL;
-+
-+	/*
-+	 * Update chain of bfq_groups as we might be handling a leaf group
-+	 * which, along with some of its relatives, has not been hooked yet
-+	 * to the private hierarchy of BFQ.
-+	 */
-+	entity = &bfqg->entity;
-+	for_each_entity(entity) {
-+		bfqg = container_of(entity, struct bfq_group, entity);
-+		BUG_ON(!bfqg);
-+		if (bfqg != bfqd->root_group) {
-+			parent = bfqg_parent(bfqg);
-+			if (!parent)
-+				parent = bfqd->root_group;
-+			BUG_ON(!parent);
-+			bfq_group_set_parent(bfqg, parent);
-+		}
-+	}
-+
-+	return bfqg;
-+}
-+
-+static void bfq_pos_tree_add_move(struct bfq_data *bfqd,
-+				  struct bfq_queue *bfqq);
-+
-+static void bfq_bfqq_expire(struct bfq_data *bfqd,
-+			    struct bfq_queue *bfqq,
-+			    bool compensate,
-+			    enum bfqq_expiration reason);
-+
-+/**
-+ * bfq_bfqq_move - migrate @bfqq to @bfqg.
-+ * @bfqd: queue descriptor.
-+ * @bfqq: the queue to move.
-+ * @bfqg: the group to move to.
-+ *
-+ * Move @bfqq to @bfqg, deactivating it from its old group and reactivating
-+ * it on the new one.  Avoid putting the entity on the old group idle tree.
-+ *
-+#ifdef BFQ_MQ
-+ * Must be called under the scheduler lock, to make sure that the blkg
-+ * owning @bfqg does not disappear (see comments in
-+ * bfq_bic_update_cgroup on guaranteeing the consistency of blkg
-+ * objects).
-+#else
-+ * Must be called under the queue lock; the cgroup owning @bfqg must
-+ * not disappear (by now this just means that we are called under
-+ * rcu_read_lock()).
-+#endif
-+ */
-+static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+			  struct bfq_group *bfqg)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+
-+	BUG_ON(!bfq_bfqq_busy(bfqq) && !RB_EMPTY_ROOT(&bfqq->sort_list));
-+	BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list) && !entity->on_st);
-+	BUG_ON(bfq_bfqq_busy(bfqq) && RB_EMPTY_ROOT(&bfqq->sort_list)
-+	       && entity->on_st &&
-+	       bfqq != bfqd->in_service_queue);
-+	BUG_ON(!bfq_bfqq_busy(bfqq) && bfqq == bfqd->in_service_queue);
-+
-+	/* If bfqq is empty, then bfq_bfqq_expire also invokes
-+	 * bfq_del_bfqq_busy, thereby removing bfqq and its entity
-+	 * from data structures related to current group. Otherwise we
-+	 * need to remove bfqq explicitly with bfq_deactivate_bfqq, as
-+	 * we do below.
-+	 */
-+	if (bfqq == bfqd->in_service_queue)
-+		bfq_bfqq_expire(bfqd, bfqd->in_service_queue,
-+				false, BFQ_BFQQ_PREEMPTED);
-+
-+	BUG_ON(entity->on_st && !bfq_bfqq_busy(bfqq)
-+	    && &bfq_entity_service_tree(entity)->idle !=
-+	       entity->tree);
-+
-+	BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list) && bfq_bfqq_busy(bfqq));
-+
-+	if (bfq_bfqq_busy(bfqq))
-+		bfq_deactivate_bfqq(bfqd, bfqq, false, false);
-+	else if (entity->on_st) {
-+		BUG_ON(&bfq_entity_service_tree(entity)->idle !=
-+		       entity->tree);
-+		bfq_put_idle_entity(bfq_entity_service_tree(entity), entity);
-+	}
-+#ifdef BFQ_MQ
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "putting blkg and bfqg %p\n", bfqg);
-+
-+	bfqg_and_blkg_put(bfqq_group(bfqq));
-+#else
-+	bfqg_put(bfqq_group(bfqq));
-+#endif
-+
-+	entity->parent = bfqg->my_entity;
-+	entity->sched_data = &bfqg->sched_data;
-+#ifdef BFQ_MQ
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "getting blkg and bfqg %p\n", bfqg);
-+
-+	/* pin down bfqg and its associated blkg  */
-+	bfqg_and_blkg_get(bfqg);
-+#else
-+	bfqg_get(bfqg);
-+#endif
-+
-+	BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list) && bfq_bfqq_busy(bfqq));
-+	if (bfq_bfqq_busy(bfqq)) {
-+		bfq_pos_tree_add_move(bfqd, bfqq);
-+		bfq_activate_bfqq(bfqd, bfqq);
-+	}
-+
-+	if (!bfqd->in_service_queue && !bfqd->rq_in_driver)
-+		bfq_schedule_dispatch(bfqd);
-+	BUG_ON(entity->on_st && !bfq_bfqq_busy(bfqq)
-+	       && &bfq_entity_service_tree(entity)->idle !=
-+	       entity->tree);
-+}
-+
-+/**
-+ * __bfq_bic_change_cgroup - move @bic to @cgroup.
-+ * @bfqd: the queue descriptor.
-+ * @bic: the bic to move.
-+ * @blkcg: the blk-cgroup to move to.
-+ *
-+#ifdef BFQ_MQ
-+ * Move bic to blkcg, assuming that bfqd->lock is held; which makes
-+ * sure that the reference to cgroup is valid across the call (see
-+ * comments in bfq_bic_update_cgroup on this issue)
-+#else
-+ * Move bic to blkcg, assuming that bfqd->queue is locked; the caller
-+ * has to make sure that the reference to cgroup is valid across the call.
-+#endif
-+ *
-+ * NOTE: an alternative approach might have been to store the current
-+ * cgroup in bfqq and getting a reference to it, reducing the lookup
-+ * time here, at the price of slightly more complex code.
-+ */
-+static struct bfq_group *__bfq_bic_change_cgroup(struct bfq_data *bfqd,
-+						struct bfq_io_cq *bic,
-+						struct blkcg *blkcg)
-+{
-+	struct bfq_queue *async_bfqq = bic_to_bfqq(bic, 0);
-+	struct bfq_queue *sync_bfqq = bic_to_bfqq(bic, 1);
-+	struct bfq_group *bfqg;
-+	struct bfq_entity *entity;
-+
-+	bfqg = bfq_find_set_group(bfqd, blkcg);
-+
-+	if (unlikely(!bfqg))
-+		bfqg = bfqd->root_group;
-+
-+	if (async_bfqq) {
-+		entity = &async_bfqq->entity;
-+
-+		if (entity->sched_data != &bfqg->sched_data) {
-+			bic_set_bfqq(bic, NULL, 0);
-+			bfq_log_bfqq(bfqd, async_bfqq,
-+				     "%p %d",
-+				     async_bfqq,
-+				     async_bfqq->ref);
-+			bfq_put_queue(async_bfqq);
-+		}
-+	}
-+
-+	if (sync_bfqq) {
-+		entity = &sync_bfqq->entity;
-+		if (entity->sched_data != &bfqg->sched_data)
-+			bfq_bfqq_move(bfqd, sync_bfqq, bfqg);
-+	}
-+
-+	return bfqg;
-+}
-+
-+static void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio)
-+{
-+	struct bfq_data *bfqd = bic_to_bfqd(bic);
-+	struct bfq_group *bfqg = NULL;
-+	uint64_t serial_nr;
-+
-+	rcu_read_lock();
-+	serial_nr = bio_blkcg(bio)->css.serial_nr;
-+
-+	/*
-+	 * Check whether blkcg has changed.  The condition may trigger
-+	 * spuriously on a newly created cic but there's no harm.
-+	 */
-+	if (unlikely(!bfqd) || likely(bic->blkcg_serial_nr == serial_nr))
-+		goto out;
-+
-+	bfqg = __bfq_bic_change_cgroup(bfqd, bic, bio_blkcg(bio));
-+#ifdef BFQ_MQ
-+	/*
-+	 * Update blkg_path for bfq_log_* functions. We cache this
-+	 * path, and update it here, for the following
-+	 * reasons. Operations on blkg objects in blk-cgroup are
-+	 * protected with the request_queue lock, and not with the
-+	 * lock that protects the instances of this scheduler
-+	 * (bfqd->lock). This exposes BFQ to the following sort of
-+	 * race.
-+	 *
-+	 * The blkg_lookup performed in bfq_get_queue, protected
-+	 * through rcu, may happen to return the address of a copy of
-+	 * the original blkg. If this is the case, then the
-+	 * bfqg_and_blkg_get performed in bfq_get_queue, to pin down
-+	 * the blkg, is useless: it does not prevent blk-cgroup code
-+	 * from destroying both the original blkg and all objects
-+	 * directly or indirectly referred by the copy of the
-+	 * blkg.
-+	 *
-+	 * On the bright side, destroy operations on a blkg invoke, as
-+	 * a first step, hooks of the scheduler associated with the
-+	 * blkg. And these hooks are executed with bfqd->lock held for
-+	 * BFQ. As a consequence, for any blkg associated with the
-+	 * request queue this instance of the scheduler is attached
-+	 * to, we are guaranteed that such a blkg is not destroyed, and
-+	 * that all the pointers it contains are consistent, while we
-+	 * are holding bfqd->lock. A blkg_lookup performed with
-+	 * bfqd->lock held then returns a fully consistent blkg, which
-+	 * remains consistent until this lock is held.
-+	 *
-+	 * Thanks to the last fact, and to the fact that: (1) bfqg has
-+	 * been obtained through a blkg_lookup in the above
-+	 * assignment, and (2) bfqd->lock is being held, here we can
-+	 * safely use the policy data for the involved blkg (i.e., the
-+	 * field bfqg->pd) to get to the blkg associated with bfqg,
-+	 * and then we can safely use any field of blkg. After we
-+	 * release bfqd->lock, even just getting blkg through this
-+	 * bfqg may cause dangling references to be traversed, as
-+	 * bfqg->pd may not exist any more.
-+	 *
-+	 * In view of the above facts, here we cache, in the bfqg, any
-+	 * blkg data we may need for this bic, and for its associated
-+	 * bfq_queue. As of now, we need to cache only the path of the
-+	 * blkg, which is used in the bfq_log_* functions.
-+	 *
-+	 * Finally, note that bfqg itself needs to be protected from
-+	 * destruction on the blkg_free of the original blkg (which
-+	 * invokes bfq_pd_free). We use an additional private
-+	 * refcounter for bfqg, to let it disappear only after no
-+	 * bfq_queue refers to it any longer.
-+	 */
-+	blkg_path(bfqg_to_blkg(bfqg), bfqg->blkg_path, sizeof(bfqg->blkg_path));
-+#endif
-+	bic->blkcg_serial_nr = serial_nr;
-+out:
-+	rcu_read_unlock();
-+}
-+
-+/**
-+ * bfq_flush_idle_tree - deactivate any entity on the idle tree of @st.
-+ * @st: the service tree being flushed.
-+ */
-+static void bfq_flush_idle_tree(struct bfq_service_tree *st)
-+{
-+	struct bfq_entity *entity = st->first_idle;
-+
-+	for (; entity ; entity = st->first_idle)
-+		__bfq_deactivate_entity(entity, false);
-+}
-+
-+/**
-+ * bfq_reparent_leaf_entity - move leaf entity to the root_group.
-+ * @bfqd: the device data structure with the root group.
-+ * @entity: the entity to move.
-+ */
-+static void bfq_reparent_leaf_entity(struct bfq_data *bfqd,
-+				     struct bfq_entity *entity)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+
-+	BUG_ON(!bfqq);
-+	bfq_bfqq_move(bfqd, bfqq, bfqd->root_group);
-+}
-+
-+/**
-+ * bfq_reparent_active_entities - move to the root group all active
-+ *                                entities.
-+ * @bfqd: the device data structure with the root group.
-+ * @bfqg: the group to move from.
-+ * @st: the service tree with the entities.
-+ */
-+static void bfq_reparent_active_entities(struct bfq_data *bfqd,
-+					 struct bfq_group *bfqg,
-+					 struct bfq_service_tree *st)
-+{
-+	struct rb_root *active = &st->active;
-+	struct bfq_entity *entity = NULL;
-+
-+	if (!RB_EMPTY_ROOT(&st->active))
-+		entity = bfq_entity_of(rb_first(active));
-+
-+	for (; entity ; entity = bfq_entity_of(rb_first(active)))
-+		bfq_reparent_leaf_entity(bfqd, entity);
-+
-+	if (bfqg->sched_data.in_service_entity)
-+		bfq_reparent_leaf_entity(bfqd,
-+			bfqg->sched_data.in_service_entity);
-+}
-+
-+/**
-+ * bfq_pd_offline - deactivate the entity associated with @pd,
-+ *		    and reparent its children entities.
-+ * @pd: descriptor of the policy going offline.
-+ *
-+ * blkio already grabs the queue_lock for us, so no need to use
-+ * RCU-based magic
-+ */
-+static void bfq_pd_offline(struct blkg_policy_data *pd)
-+{
-+	struct bfq_service_tree *st;
-+	struct bfq_group *bfqg;
-+	struct bfq_data *bfqd;
-+	struct bfq_entity *entity;
-+#ifdef BFQ_MQ
-+	unsigned long flags;
-+#endif
-+	int i;
-+
-+	BUG_ON(!pd);
-+	bfqg = pd_to_bfqg(pd);
-+	BUG_ON(!bfqg);
-+	bfqd = bfqg->bfqd;
-+	BUG_ON(bfqd && !bfqd->root_group);
-+
-+	entity = bfqg->my_entity;
-+
-+#ifdef BFQ_MQ
-+	spin_lock_irqsave(&bfqd->lock, flags);
-+#endif
-+
-+	if (!entity) /* root group */
-+		goto put_async_queues;
-+
-+	/*
-+	 * Empty all service_trees belonging to this group before
-+	 * deactivating the group itself.
-+	 */
-+	for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) {
-+		BUG_ON(!bfqg->sched_data.service_tree);
-+		st = bfqg->sched_data.service_tree + i;
-+		/*
-+		 * The idle tree may still contain bfq_queues belonging
-+		 * to exited task because they never migrated to a different
-+		 * cgroup from the one being destroyed now.
-+		 */
-+		bfq_flush_idle_tree(st);
-+
-+		/*
-+		 * It may happen that some queues are still active
-+		 * (busy) upon group destruction (if the corresponding
-+		 * processes have been forced to terminate). We move
-+		 * all the leaf entities corresponding to these queues
-+		 * to the root_group.
-+		 * Also, it may happen that the group has an entity
-+		 * in service, which is disconnected from the active
-+		 * tree: it must be moved, too.
-+		 * There is no need to put the sync queues, as the
-+		 * scheduler has taken no reference.
-+		 */
-+		bfq_reparent_active_entities(bfqd, bfqg, st);
-+		BUG_ON(!RB_EMPTY_ROOT(&st->active));
-+		BUG_ON(!RB_EMPTY_ROOT(&st->idle));
-+	}
-+	BUG_ON(bfqg->sched_data.next_in_service);
-+	BUG_ON(bfqg->sched_data.in_service_entity);
-+
-+	__bfq_deactivate_entity(entity, false);
-+
-+put_async_queues:
-+	bfq_put_async_queues(bfqd, bfqg);
-+
-+#ifdef BFQ_MQ
-+	spin_unlock_irqrestore(&bfqd->lock, flags);
-+#endif
-+	/*
-+	 * @blkg is going offline and will be ignored by
-+	 * blkg_[rw]stat_recursive_sum().  Transfer stats to the parent so
-+	 * that they don't get lost.  If IOs complete after this point, the
-+	 * stats for them will be lost.  Oh well...
-+	 */
-+	bfqg_stats_xfer_dead(bfqg);
-+}
-+
-+static void bfq_end_wr_async(struct bfq_data *bfqd)
-+{
-+	struct blkcg_gq *blkg;
-+
-+	list_for_each_entry(blkg, &bfqd->queue->blkg_list, q_node) {
-+		struct bfq_group *bfqg = blkg_to_bfqg(blkg);
-+		BUG_ON(!bfqg);
-+
-+		bfq_end_wr_async_queues(bfqd, bfqg);
-+	}
-+	bfq_end_wr_async_queues(bfqd, bfqd->root_group);
-+}
-+
-+static int bfq_io_show_weight(struct seq_file *sf, void *v)
-+{
-+	struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
-+	struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg);
-+	unsigned int val = 0;
-+
-+	if (bfqgd)
-+		val = bfqgd->weight;
-+
-+	seq_printf(sf, "%u\n", val);
-+
-+	return 0;
-+}
-+
-+static int bfq_io_set_weight_legacy(struct cgroup_subsys_state *css,
-+				    struct cftype *cftype,
-+				    u64 val)
-+{
-+	struct blkcg *blkcg = css_to_blkcg(css);
-+	struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg);
-+	struct blkcg_gq *blkg;
-+	int ret = -ERANGE;
-+
-+	if (val < BFQ_MIN_WEIGHT || val > BFQ_MAX_WEIGHT)
-+		return ret;
-+
-+	ret = 0;
-+	spin_lock_irq(&blkcg->lock);
-+	bfqgd->weight = (unsigned short)val;
-+	hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
-+		struct bfq_group *bfqg = blkg_to_bfqg(blkg);
-+
-+		if (!bfqg)
-+			continue;
-+		/*
-+		 * Setting the prio_changed flag of the entity
-+		 * to 1 with new_weight == weight would re-set
-+		 * the value of the weight to its ioprio mapping.
-+		 * Set the flag only if necessary.
-+		 */
-+		if ((unsigned short)val != bfqg->entity.new_weight) {
-+			bfqg->entity.new_weight = (unsigned short)val;
-+			/*
-+			 * Make sure that the above new value has been
-+			 * stored in bfqg->entity.new_weight before
-+			 * setting the prio_changed flag. In fact,
-+			 * this flag may be read asynchronously (in
-+			 * critical sections protected by a different
-+			 * lock than that held here), and finding this
-+			 * flag set may cause the execution of the code
-+			 * for updating parameters whose value may
-+			 * depend also on bfqg->entity.new_weight (in
-+			 * __bfq_entity_update_weight_prio).
-+			 * This barrier makes sure that the new value
-+			 * of bfqg->entity.new_weight is correctly
-+			 * seen in that code.
-+			 */
-+			smp_wmb();
-+			bfqg->entity.prio_changed = 1;
-+		}
-+	}
-+	spin_unlock_irq(&blkcg->lock);
-+
-+	return ret;
-+}
-+
-+static ssize_t bfq_io_set_weight(struct kernfs_open_file *of,
-+				 char *buf, size_t nbytes,
-+				 loff_t off)
-+{
-+	u64 weight;
-+	/* First unsigned long found in the file is used */
-+	int ret = kstrtoull(strim(buf), 0, &weight);
-+
-+	if (ret)
-+		return ret;
-+
-+	ret = bfq_io_set_weight_legacy(of_css(of), NULL, weight);
-+	return ret ?: nbytes;
-+}
-+
-+#ifdef CONFIG_DEBUG_BLK_CGROUP
-+static int bfqg_print_stat(struct seq_file *sf, void *v)
-+{
-+	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_stat,
-+			  &blkcg_policy_bfq, seq_cft(sf)->private, false);
-+	return 0;
-+}
-+
-+static int bfqg_print_rwstat(struct seq_file *sf, void *v)
-+{
-+	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_rwstat,
-+			  &blkcg_policy_bfq, seq_cft(sf)->private, true);
-+	return 0;
-+}
-+
-+static u64 bfqg_prfill_stat_recursive(struct seq_file *sf,
-+				      struct blkg_policy_data *pd, int off)
-+{
-+	u64 sum = blkg_stat_recursive_sum(pd_to_blkg(pd),
-+					  &blkcg_policy_bfq, off);
-+	return __blkg_prfill_u64(sf, pd, sum);
-+}
-+
-+static u64 bfqg_prfill_rwstat_recursive(struct seq_file *sf,
-+					struct blkg_policy_data *pd, int off)
-+{
-+	struct blkg_rwstat sum = blkg_rwstat_recursive_sum(pd_to_blkg(pd),
-+							   &blkcg_policy_bfq,
-+							   off);
-+	return __blkg_prfill_rwstat(sf, pd, &sum);
-+}
-+
-+static int bfqg_print_stat_recursive(struct seq_file *sf, void *v)
-+{
-+	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
-+			  bfqg_prfill_stat_recursive, &blkcg_policy_bfq,
-+			  seq_cft(sf)->private, false);
-+	return 0;
-+}
-+
-+static int bfqg_print_rwstat_recursive(struct seq_file *sf, void *v)
-+{
-+	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
-+			  bfqg_prfill_rwstat_recursive, &blkcg_policy_bfq,
-+			  seq_cft(sf)->private, true);
-+	return 0;
-+}
-+
-+static u64 bfqg_prfill_sectors(struct seq_file *sf, struct blkg_policy_data *pd,
-+			       int off)
-+{
-+	u64 sum = blkg_rwstat_total(&pd->blkg->stat_bytes);
-+
-+	return __blkg_prfill_u64(sf, pd, sum >> 9);
-+}
-+
-+static int bfqg_print_stat_sectors(struct seq_file *sf, void *v)
-+{
-+	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
-+			  bfqg_prfill_sectors, &blkcg_policy_bfq, 0, false);
-+	return 0;
-+}
-+
-+static u64 bfqg_prfill_sectors_recursive(struct seq_file *sf,
-+					 struct blkg_policy_data *pd, int off)
-+{
-+	struct blkg_rwstat tmp = blkg_rwstat_recursive_sum(pd->blkg, NULL,
-+					offsetof(struct blkcg_gq, stat_bytes));
-+	u64 sum = atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_READ]) +
-+		atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_WRITE]);
-+
-+	return __blkg_prfill_u64(sf, pd, sum >> 9);
-+}
-+
-+static int bfqg_print_stat_sectors_recursive(struct seq_file *sf, void *v)
-+{
-+	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
-+			  bfqg_prfill_sectors_recursive, &blkcg_policy_bfq, 0,
-+			  false);
-+	return 0;
-+}
-+
-+
-+static u64 bfqg_prfill_avg_queue_size(struct seq_file *sf,
-+				      struct blkg_policy_data *pd, int off)
-+{
-+	struct bfq_group *bfqg = pd_to_bfqg(pd);
-+	u64 samples = blkg_stat_read(&bfqg->stats.avg_queue_size_samples);
-+	u64 v = 0;
-+
-+	if (samples) {
-+		v = blkg_stat_read(&bfqg->stats.avg_queue_size_sum);
-+		v = div64_u64(v, samples);
-+	}
-+	__blkg_prfill_u64(sf, pd, v);
-+	return 0;
-+}
-+
-+/* print avg_queue_size */
-+static int bfqg_print_avg_queue_size(struct seq_file *sf, void *v)
-+{
-+	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
-+			  bfqg_prfill_avg_queue_size, &blkcg_policy_bfq,
-+			  0, false);
-+	return 0;
-+}
-+#endif /* CONFIG_DEBUG_BLK_CGROUP */
-+
-+static struct bfq_group *
-+bfq_create_group_hierarchy(struct bfq_data *bfqd, int node)
-+{
-+	int ret;
-+
-+	ret = blkcg_activate_policy(bfqd->queue, &blkcg_policy_bfq);
-+	if (ret)
-+		return NULL;
-+
-+	return blkg_to_bfqg(bfqd->queue->root_blkg);
-+}
-+
-+#ifdef BFQ_MQ
-+#define BFQ_CGROUP_FNAME(param) "bfq-mq."#param
-+#else
-+#define BFQ_CGROUP_FNAME(param) "bfq-sq."#param
-+#endif
-+
-+static struct cftype bfq_blkcg_legacy_files[] = {
-+	{
-+		.name = BFQ_CGROUP_FNAME(weight),
-+		.flags = CFTYPE_NOT_ON_ROOT,
-+		.seq_show = bfq_io_show_weight,
-+		.write_u64 = bfq_io_set_weight_legacy,
-+	},
-+
-+	/* statistics, covers only the tasks in the bfqg */
-+	{
-+		.name = BFQ_CGROUP_FNAME(io_service_bytes),
-+		.private = (unsigned long)&blkcg_policy_bfq,
-+		.seq_show = blkg_print_stat_bytes,
-+	},
-+	{
-+		.name = BFQ_CGROUP_FNAME(io_serviced),
-+		.private = (unsigned long)&blkcg_policy_bfq,
-+		.seq_show = blkg_print_stat_ios,
-+	},
-+#ifdef CONFIG_DEBUG_BLK_CGROUP
-+	{
-+		.name = BFQ_CGROUP_FNAME(time),
-+		.private = offsetof(struct bfq_group, stats.time),
-+		.seq_show = bfqg_print_stat,
-+	},
-+	{
-+		.name = BFQ_CGROUP_FNAME(sectors),
-+		.seq_show = bfqg_print_stat_sectors,
-+	},
-+	{
-+		.name = BFQ_CGROUP_FNAME(io_service_time),
-+		.private = offsetof(struct bfq_group, stats.service_time),
-+		.seq_show = bfqg_print_rwstat,
-+	},
-+	{
-+		.name = BFQ_CGROUP_FNAME(io_wait_time),
-+		.private = offsetof(struct bfq_group, stats.wait_time),
-+		.seq_show = bfqg_print_rwstat,
-+	},
-+	{
-+		.name = BFQ_CGROUP_FNAME(io_merged),
-+		.private = offsetof(struct bfq_group, stats.merged),
-+		.seq_show = bfqg_print_rwstat,
-+	},
-+	{
-+		.name = BFQ_CGROUP_FNAME(io_queued),
-+		.private = offsetof(struct bfq_group, stats.queued),
-+		.seq_show = bfqg_print_rwstat,
-+	},
-+#endif /* CONFIG_DEBUG_BLK_CGROUP */
-+
-+	/* the same statictics which cover the bfqg and its descendants */
-+	{
-+		.name = BFQ_CGROUP_FNAME(io_service_bytes_recursive),
-+		.private = (unsigned long)&blkcg_policy_bfq,
-+		.seq_show = blkg_print_stat_bytes_recursive,
-+	},
-+	{
-+		.name = BFQ_CGROUP_FNAME(io_serviced_recursive),
-+		.private = (unsigned long)&blkcg_policy_bfq,
-+		.seq_show = blkg_print_stat_ios_recursive,
-+	},
-+#ifdef CONFIG_DEBUG_BLK_CGROUP
-+	{
-+		.name = BFQ_CGROUP_FNAME(time_recursive),
-+		.private = offsetof(struct bfq_group, stats.time),
-+		.seq_show = bfqg_print_stat_recursive,
-+	},
-+	{
-+		.name = BFQ_CGROUP_FNAME(sectors_recursive),
-+		.seq_show = bfqg_print_stat_sectors_recursive,
-+	},
-+	{
-+		.name = BFQ_CGROUP_FNAME(io_service_time_recursive),
-+		.private = offsetof(struct bfq_group, stats.service_time),
-+		.seq_show = bfqg_print_rwstat_recursive,
-+	},
-+	{
-+		.name = BFQ_CGROUP_FNAME(io_wait_time_recursive),
-+		.private = offsetof(struct bfq_group, stats.wait_time),
-+		.seq_show = bfqg_print_rwstat_recursive,
-+	},
-+	{
-+		.name = BFQ_CGROUP_FNAME(io_merged_recursive),
-+		.private = offsetof(struct bfq_group, stats.merged),
-+		.seq_show = bfqg_print_rwstat_recursive,
-+	},
-+	{
-+		.name = BFQ_CGROUP_FNAME(io_queued_recursive),
-+		.private = offsetof(struct bfq_group, stats.queued),
-+		.seq_show = bfqg_print_rwstat_recursive,
-+	},
-+	{
-+		.name = BFQ_CGROUP_FNAME(avg_queue_size),
-+		.seq_show = bfqg_print_avg_queue_size,
-+	},
-+	{
-+		.name = BFQ_CGROUP_FNAME(group_wait_time),
-+		.private = offsetof(struct bfq_group, stats.group_wait_time),
-+		.seq_show = bfqg_print_stat,
-+	},
-+	{
-+		.name = BFQ_CGROUP_FNAME(idle_time),
-+		.private = offsetof(struct bfq_group, stats.idle_time),
-+		.seq_show = bfqg_print_stat,
-+	},
-+	{
-+		.name = BFQ_CGROUP_FNAME(empty_time),
-+		.private = offsetof(struct bfq_group, stats.empty_time),
-+		.seq_show = bfqg_print_stat,
-+	},
-+	{
-+		.name = BFQ_CGROUP_FNAME(dequeue),
-+		.private = offsetof(struct bfq_group, stats.dequeue),
-+		.seq_show = bfqg_print_stat,
-+	},
-+#endif	/* CONFIG_DEBUG_BLK_CGROUP */
-+	{ }	/* terminate */
-+};
-+
-+static struct cftype bfq_blkg_files[] = {
-+	{
-+		.name = BFQ_CGROUP_FNAME(weight),
-+		.flags = CFTYPE_NOT_ON_ROOT,
-+		.seq_show = bfq_io_show_weight,
-+		.write = bfq_io_set_weight,
-+	},
-+	{} /* terminate */
-+};
-+
-+#undef BFQ_CGROUP_FNAME
-+
-+#else /* BFQ_GROUP_IOSCHED_ENABLED */
-+
-+static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+			  struct bfq_group *bfqg) {}
-+
-+static void bfq_init_entity(struct bfq_entity *entity,
-+			    struct bfq_group *bfqg)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+
-+	entity->weight = entity->new_weight;
-+	entity->orig_weight = entity->new_weight;
-+	if (bfqq) {
-+		bfqq->ioprio = bfqq->new_ioprio;
-+		bfqq->ioprio_class = bfqq->new_ioprio_class;
-+	}
-+	entity->sched_data = &bfqg->sched_data;
-+}
-+
-+static void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio) {}
-+
-+static void bfq_end_wr_async(struct bfq_data *bfqd)
-+{
-+	bfq_end_wr_async_queues(bfqd, bfqd->root_group);
-+}
-+
-+static struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd,
-+					    struct blkcg *blkcg)
-+{
-+	return bfqd->root_group;
-+}
-+
-+static struct bfq_group *bfqq_group(struct bfq_queue *bfqq)
-+{
-+	return bfqq->bfqd->root_group;
-+}
-+
-+static struct bfq_group *
-+bfq_create_group_hierarchy(struct bfq_data *bfqd, int node)
-+{
-+	struct bfq_group *bfqg;
-+	int i;
-+
-+	bfqg = kmalloc_node(sizeof(*bfqg), GFP_KERNEL | __GFP_ZERO, node);
-+	if (!bfqg)
-+		return NULL;
-+
-+	for (i = 0; i < BFQ_IOPRIO_CLASSES; i++)
-+		bfqg->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT;
-+
-+	return bfqg;
-+}
-+#endif
-diff --git a/block/bfq-ioc.c b/block/bfq-ioc.c
-new file mode 100644
-index 000000000000..fb7bb8f08b75
---- /dev/null
-+++ b/block/bfq-ioc.c
-@@ -0,0 +1,36 @@
-+/*
-+ * BFQ: I/O context handling.
-+ *
-+ * Based on ideas and code from CFQ:
-+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
-+ *
-+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
-+ *		      Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2010 Paolo Valente <paolo.valente@unimore.it>
-+ */
-+
-+/**
-+ * icq_to_bic - convert iocontext queue structure to bfq_io_cq.
-+ * @icq: the iocontext queue.
-+ */
-+static struct bfq_io_cq *icq_to_bic(struct io_cq *icq)
-+{
-+	/* bic->icq is the first member, %NULL will convert to %NULL */
-+	return container_of(icq, struct bfq_io_cq, icq);
-+}
-+
-+/**
-+ * bfq_bic_lookup - search into @ioc a bic associated to @bfqd.
-+ * @bfqd: the lookup key.
-+ * @ioc: the io_context of the process doing I/O.
-+ *
-+ * Queue lock must be held.
-+ */
-+static struct bfq_io_cq *bfq_bic_lookup(struct bfq_data *bfqd,
-+					struct io_context *ioc)
-+{
-+	if (ioc)
-+		return icq_to_bic(ioc_lookup_icq(ioc, bfqd->queue));
-+	return NULL;
-+}
-diff --git a/block/bfq-mq-iosched.c b/block/bfq-mq-iosched.c
-new file mode 100644
-index 000000000000..47a49d9e6512
---- /dev/null
-+++ b/block/bfq-mq-iosched.c
-@@ -0,0 +1,6548 @@
-+/*
-+ * Budget Fair Queueing (BFQ) I/O scheduler.
-+ *
-+ * Based on ideas and code from CFQ:
-+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
-+ *
-+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
-+ *		      Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2017 Paolo Valente <paolo.valente@linaro.org>
-+ *
-+ * Licensed under the GPL-2 as detailed in the accompanying COPYING.BFQ
-+ * file.
-+ *
-+ * BFQ is a proportional-share I/O scheduler, with some extra
-+ * low-latency capabilities. BFQ also supports full hierarchical
-+ * scheduling through cgroups. Next paragraphs provide an introduction
-+ * on BFQ inner workings. Details on BFQ benefits and usage can be
-+ * found in Documentation/block/bfq-iosched.txt.
-+ *
-+ * BFQ is a proportional-share storage-I/O scheduling algorithm based
-+ * on the slice-by-slice service scheme of CFQ. But BFQ assigns
-+ * budgets, measured in number of sectors, to processes instead of
-+ * time slices. The device is not granted to the in-service process
-+ * for a given time slice, but until it has exhausted its assigned
-+ * budget. This change from the time to the service domain enables BFQ
-+ * to distribute the device throughput among processes as desired,
-+ * without any distortion due to throughput fluctuations, or to device
-+ * internal queueing. BFQ uses an ad hoc internal scheduler, called
-+ * B-WF2Q+, to schedule processes according to their budgets. More
-+ * precisely, BFQ schedules queues associated with processes. Thanks to
-+ * the accurate policy of B-WF2Q+, BFQ can afford to assign high
-+ * budgets to I/O-bound processes issuing sequential requests (to
-+ * boost the throughput), and yet guarantee a low latency to
-+ * interactive and soft real-time applications.
-+ *
-+ * In particular, BFQ schedules I/O so as to achieve the latter goal--
-+ * low latency for interactive and soft real-time applications--if the
-+ * low_latency parameter is set (default configuration). To this
-+ * purpose, BFQ constantly tries to detect whether the I/O requests in
-+ * a bfq_queue come from an interactive or a soft real-time
-+ * application. For brevity, in these cases, the queue is said to be
-+ * interactive or soft real-time. In both cases, BFQ privileges the
-+ * service of the queue, over that of non-interactive and
-+ * non-soft-real-time queues. This privileging is performed, mainly,
-+ * by raising the weight of the queue. So, for brevity, we call just
-+ * weight-raising periods the time periods during which a queue is
-+ * privileged, because deemed interactive or soft real-time.
-+ *
-+ * The detection of soft real-time queues/applications is described in
-+ * detail in the comments on the function
-+ * bfq_bfqq_softrt_next_start. On the other hand, the detection of an
-+ * interactive queue works as follows: a queue is deemed interactive
-+ * if it is constantly non empty only for a limited time interval,
-+ * after which it does become empty. The queue may be deemed
-+ * interactive again (for a limited time), if it restarts being
-+ * constantly non empty, provided that this happens only after the
-+ * queue has remained empty for a given minimum idle time.
-+ *
-+ * By default, BFQ computes automatically the above maximum time
-+ * interval, i.e., the time interval after which a constantly
-+ * non-empty queue stops being deemed interactive. Since a queue is
-+ * weight-raised while it is deemed interactive, this maximum time
-+ * interval happens to coincide with the (maximum) duration of the
-+ * weight-raising for interactive queues.
-+ *
-+ * NOTE: if the main or only goal, with a given device, is to achieve
-+ * the maximum-possible throughput at all times, then do switch off
-+ * all low-latency heuristics for that device, by setting low_latency
-+ * to 0.
-+ *
-+ * BFQ is described in [1], where also a reference to the initial,
-+ * more theoretical paper on BFQ can be found. The interested reader
-+ * can find in the latter paper full details on the main algorithm, as
-+ * well as formulas of the guarantees and formal proofs of all the
-+ * properties.  With respect to the version of BFQ presented in these
-+ * papers, this implementation adds a few more heuristics, such as the
-+ * one that guarantees a low latency to soft real-time applications,
-+ * and a hierarchical extension based on H-WF2Q+.
-+ *
-+ * B-WF2Q+ is based on WF2Q+, that is described in [2], together with
-+ * H-WF2Q+, while the augmented tree used to implement B-WF2Q+ with O(log N)
-+ * complexity derives from the one introduced with EEVDF in [3].
-+ *
-+ * [1] P. Valente, A. Avanzini, "Evolution of the BFQ Storage I/O
-+ *   Scheduler", Proceedings of the First Workshop on Mobile System
-+ *   Technologies (MST-2015), May 2015.
-+ *   http://algogroup.unimore.it/people/paolo/disk_sched/mst-2015.pdf
-+ *
-+ * http://algogroup.unimo.it/people/paolo/disk_sched/bf1-v1-suite-results.pdf
-+ *
-+ * [2] Jon C.R. Bennett and H. Zhang, ``Hierarchical Packet Fair Queueing
-+ *     Algorithms,'' IEEE/ACM Transactions on Networking, 5(5):675-689,
-+ *     Oct 1997.
-+ *
-+ * http://www.cs.cmu.edu/~hzhang/papers/TON-97-Oct.ps.gz
-+ *
-+ * [3] I. Stoica and H. Abdel-Wahab, ``Earliest Eligible Virtual Deadline
-+ *     First: A Flexible and Accurate Mechanism for Proportional Share
-+ *     Resource Allocation,'' technical report.
-+ *
-+ * http://www.cs.berkeley.edu/~istoica/papers/eevdf-tr-95.pdf
-+ */
-+#include <linux/module.h>
-+#include <linux/slab.h>
-+#include <linux/blkdev.h>
-+#include <linux/cgroup.h>
-+#include <linux/elevator.h>
-+#include <linux/jiffies.h>
-+#include <linux/rbtree.h>
-+#include <linux/ioprio.h>
-+#include <linux/sbitmap.h>
-+#include <linux/delay.h>
-+
-+#include "blk.h"
-+#include "blk-mq.h"
-+#include "blk-mq-tag.h"
-+#include "blk-mq-sched.h"
-+#include "bfq-mq.h"
-+#include "blk-wbt.h"
-+
-+/* Expiration time of sync (0) and async (1) requests, in ns. */
-+static const u64 bfq_fifo_expire[2] = { NSEC_PER_SEC / 4, NSEC_PER_SEC / 8 };
-+
-+/* Maximum backwards seek, in KiB. */
-+static const int bfq_back_max = (16 * 1024);
-+
-+/* Penalty of a backwards seek, in number of sectors. */
-+static const int bfq_back_penalty = 2;
-+
-+/* Idling period duration, in ns. */
-+static u32 bfq_slice_idle = (NSEC_PER_SEC / 125);
-+
-+/* Minimum number of assigned budgets for which stats are safe to compute. */
-+static const int bfq_stats_min_budgets = 194;
-+
-+/* Default maximum budget values, in sectors and number of requests. */
-+static const int bfq_default_max_budget = (16 * 1024);
-+
-+/*
-+ * When a sync request is dispatched, the queue that contains that
-+ * request, and all the ancestor entities of that queue, are charged
-+ * with the number of sectors of the request. In constrast, if the
-+ * request is async, then the queue and its ancestor entities are
-+ * charged with the number of sectors of the request, multiplied by
-+ * the factor below. This throttles the bandwidth for async I/O,
-+ * w.r.t. to sync I/O, and it is done to counter the tendency of async
-+ * writes to steal I/O throughput to reads.
-+ *
-+ * The current value of this parameter is the result of a tuning with
-+ * several hardware and software configurations. We tried to find the
-+ * lowest value for which writes do not cause noticeable problems to
-+ * reads. In fact, the lower this parameter, the stabler I/O control,
-+ * in the following respect.  The lower this parameter is, the less
-+ * the bandwidth enjoyed by a group decreases
-+ * - when the group does writes, w.r.t. to when it does reads;
-+ * - when other groups do reads, w.r.t. to when they do writes.
-+ */
-+static const int bfq_async_charge_factor = 3;
-+
-+/* Default timeout values, in jiffies, approximating CFQ defaults. */
-+static const int bfq_timeout = (HZ / 8);
-+
-+/*
-+ * Time limit for merging (see comments in bfq_setup_cooperator). Set
-+ * to the slowest value that, in our tests, proved to be effective in
-+ * removing false positives, while not causing true positives to miss
-+ * queue merging.
-+ *
-+ * As can be deduced from the low time limit below, queue merging, if
-+ * successful, happens at the very beggining of the I/O of the involved
-+ * cooperating processes, as a consequence of the arrival of the very
-+ * first requests from each cooperator.  After that, there is very
-+ * little chance to find cooperators.
-+ */
-+static const unsigned long bfq_merge_time_limit = HZ/10;
-+
-+#define MAX_LENGTH_REASON_NAME 25
-+
-+static const char reason_name[][MAX_LENGTH_REASON_NAME] = {"TOO_IDLE",
-+"BUDGET_TIMEOUT", "BUDGET_EXHAUSTED", "NO_MORE_REQUESTS",
-+"PREEMPTED"};
-+
-+static struct kmem_cache *bfq_pool;
-+
-+/* Below this threshold (in ns), we consider thinktime immediate. */
-+#define BFQ_MIN_TT		(2 * NSEC_PER_MSEC)
-+
-+/* hw_tag detection: parallel requests threshold and min samples needed. */
-+#define BFQ_HW_QUEUE_THRESHOLD	3
-+#define BFQ_HW_QUEUE_SAMPLES	32
-+
-+#define BFQQ_SEEK_THR		(sector_t)(8 * 100)
-+#define BFQQ_SECT_THR_NONROT	(sector_t)(2 * 32)
-+#define BFQ_RQ_SEEKY(bfqd, last_pos, rq) \
-+				(get_sdist(last_pos, rq) >  \
-+				 BFQQ_SEEK_THR && \
-+				 (!blk_queue_nonrot(bfqd->queue) || \
-+				  blk_rq_sectors(rq) < BFQQ_SECT_THR_NONROT))
-+#define BFQQ_CLOSE_THR		(sector_t)(8 * 1024)
-+#define BFQQ_SEEKY(bfqq)	(hweight32(bfqq->seek_history) > 19)
-+
-+/* Min number of samples required to perform peak-rate update */
-+#define BFQ_RATE_MIN_SAMPLES	32
-+/* Min observation time interval required to perform a peak-rate update (ns) */
-+#define BFQ_RATE_MIN_INTERVAL	(300*NSEC_PER_MSEC)
-+/* Target observation time interval for a peak-rate update (ns) */
-+#define BFQ_RATE_REF_INTERVAL	NSEC_PER_SEC
-+
-+/*
-+ * Shift used for peak-rate fixed precision calculations.
-+ * With
-+ * - the current shift: 16 positions
-+ * - the current type used to store rate: u32
-+ * - the current unit of measure for rate: [sectors/usec], or, more precisely,
-+ *   [(sectors/usec) / 2^BFQ_RATE_SHIFT] to take into account the shift,
-+ * the range of rates that can be stored is
-+ * [1 / 2^BFQ_RATE_SHIFT, 2^(32 - BFQ_RATE_SHIFT)] sectors/usec =
-+ * [1 / 2^16, 2^16] sectors/usec = [15e-6, 65536] sectors/usec =
-+ * [15, 65G] sectors/sec
-+ * Which, assuming a sector size of 512B, corresponds to a range of
-+ * [7.5K, 33T] B/sec
-+ */
-+#define BFQ_RATE_SHIFT		16
-+
-+/*
-+ * When configured for computing the duration of the weight-raising
-+ * for interactive queues automatically (see the comments at the
-+ * beginning of this file), BFQ does it using the following formula:
-+ * duration = (ref_rate / r) * ref_wr_duration,
-+ * where r is the peak rate of the device, and ref_rate and
-+ * ref_wr_duration are two reference parameters.  In particular,
-+ * ref_rate is the peak rate of the reference storage device (see
-+ * below), and ref_wr_duration is about the maximum time needed, with
-+ * BFQ and while reading two files in parallel, to load typical large
-+ * applications on the reference device (see the comments on
-+ * max_service_from_wr below, for more details on how ref_wr_duration
-+ * is obtained).  In practice, the slower/faster the device at hand
-+ * is, the more/less it takes to load applications with respect to the
-+ * reference device.  Accordingly, the longer/shorter BFQ grants
-+ * weight raising to interactive applications.
-+ *
-+ * BFQ uses two different reference pairs (ref_rate, ref_wr_duration),
-+ * depending on whether the device is rotational or non-rotational.
-+ *
-+ * In the following definitions, ref_rate[0] and ref_wr_duration[0]
-+ * are the reference values for a rotational device, whereas
-+ * ref_rate[1] and ref_wr_duration[1] are the reference values for a
-+ * non-rotational device. The reference rates are not the actual peak
-+ * rates of the devices used as a reference, but slightly lower
-+ * values. The reason for using slightly lower values is that the
-+ * peak-rate estimator tends to yield slightly lower values than the
-+ * actual peak rate (it can yield the actual peak rate only if there
-+ * is only one process doing I/O, and the process does sequential
-+ * I/O).
-+ *
-+ * The reference peak rates are measured in sectors/usec, left-shifted
-+ * by BFQ_RATE_SHIFT.
-+ */
-+static int ref_rate[2] = {14000, 33000};
-+/*
-+ * To improve readability, a conversion function is used to initialize
-+ * the following array, which entails that the array can be
-+ * initialized only in a function.
-+ */
-+static int ref_wr_duration[2];
-+
-+/*
-+ * BFQ uses the above-detailed, time-based weight-raising mechanism to
-+ * privilege interactive tasks. This mechanism is vulnerable to the
-+ * following false positives: I/O-bound applications that will go on
-+ * doing I/O for much longer than the duration of weight
-+ * raising. These applications have basically no benefit from being
-+ * weight-raised at the beginning of their I/O. On the opposite end,
-+ * while being weight-raised, these applications
-+ * a) unjustly steal throughput to applications that may actually need
-+ * low latency;
-+ * b) make BFQ uselessly perform device idling; device idling results
-+ * in loss of device throughput with most flash-based storage, and may
-+ * increase latencies when used purposelessly.
-+ *
-+ * BFQ tries to reduce these problems, by adopting the following
-+ * countermeasure. To introduce this countermeasure, we need first to
-+ * finish explaining how the duration of weight-raising for
-+ * interactive tasks is computed.
-+ *
-+ * For a bfq_queue deemed as interactive, the duration of weight
-+ * raising is dynamically adjusted, as a function of the estimated
-+ * peak rate of the device, so as to be equal to the time needed to
-+ * execute the 'largest' interactive task we benchmarked so far. By
-+ * largest task, we mean the task for which each involved process has
-+ * to do more I/O than for any of the other tasks we benchmarked. This
-+ * reference interactive task is the start-up of LibreOffice Writer,
-+ * and in this task each process/bfq_queue needs to have at most ~110K
-+ * sectors transferred.
-+ *
-+ * This last piece of information enables BFQ to reduce the actual
-+ * duration of weight-raising for at least one class of I/O-bound
-+ * applications: those doing sequential or quasi-sequential I/O. An
-+ * example is file copy. In fact, once started, the main I/O-bound
-+ * processes of these applications usually consume the above 110K
-+ * sectors in much less time than the processes of an application that
-+ * is starting, because these I/O-bound processes will greedily devote
-+ * almost all their CPU cycles only to their target,
-+ * throughput-friendly I/O operations. This is even more true if BFQ
-+ * happens to be underestimating the device peak rate, and thus
-+ * overestimating the duration of weight raising. But, according to
-+ * our measurements, once transferred 110K sectors, these processes
-+ * have no right to be weight-raised any longer.
-+ *
-+ * Basing on the last consideration, BFQ ends weight-raising for a
-+ * bfq_queue if the latter happens to have received an amount of
-+ * service at least equal to the following constant. The constant is
-+ * set to slightly more than 110K, to have a minimum safety margin.
-+ *
-+ * This early ending of weight-raising reduces the amount of time
-+ * during which interactive false positives cause the two problems
-+ * described at the beginning of these comments.
-+ */
-+static const unsigned long max_service_from_wr = 120000;
-+
-+#define BFQ_SERVICE_TREE_INIT	((struct bfq_service_tree)		\
-+				{ RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 })
-+
-+#define RQ_BIC(rq)		icq_to_bic((rq)->elv.priv[0])
-+#define RQ_BFQQ(rq)		((rq)->elv.priv[1])
-+
-+/**
-+ * icq_to_bic - convert iocontext queue structure to bfq_io_cq.
-+ * @icq: the iocontext queue.
-+ */
-+static struct bfq_io_cq *icq_to_bic(struct io_cq *icq)
-+{
-+	/* bic->icq is the first member, %NULL will convert to %NULL */
-+	return container_of(icq, struct bfq_io_cq, icq);
-+}
-+
-+/**
-+ * bfq_bic_lookup - search into @ioc a bic associated to @bfqd.
-+ * @bfqd: the lookup key.
-+ * @ioc: the io_context of the process doing I/O.
-+ * @q: the request queue.
-+ */
-+static struct bfq_io_cq *bfq_bic_lookup(struct bfq_data *bfqd,
-+					struct io_context *ioc,
-+					struct request_queue *q)
-+{
-+	if (ioc) {
-+		unsigned long flags;
-+		struct bfq_io_cq *icq;
-+
-+		spin_lock_irqsave(q->queue_lock, flags);
-+		icq = icq_to_bic(ioc_lookup_icq(ioc, q));
-+		spin_unlock_irqrestore(q->queue_lock, flags);
-+
-+		return icq;
-+	}
-+
-+	return NULL;
-+}
-+
-+/*
-+ * Scheduler run of queue, if there are requests pending and no one in the
-+ * driver that will restart queueing.
-+ */
-+static void bfq_schedule_dispatch(struct bfq_data *bfqd)
-+{
-+	if (bfqd->queued != 0) {
-+		bfq_log(bfqd, "");
-+		blk_mq_run_hw_queues(bfqd->queue, true);
-+	}
-+}
-+
-+#define BFQ_MQ
-+#include "bfq-sched.c"
-+#include "bfq-cgroup-included.c"
-+
-+#define bfq_class_idle(bfqq)	((bfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
-+#define bfq_class_rt(bfqq)	((bfqq)->ioprio_class == IOPRIO_CLASS_RT)
-+
-+#define bfq_sample_valid(samples)	((samples) > 80)
-+
-+/*
-+ * Lifted from AS - choose which of rq1 and rq2 that is best served now.
-+ * We choose the request that is closesr to the head right now.  Distance
-+ * behind the head is penalized and only allowed to a certain extent.
-+ */
-+static struct request *bfq_choose_req(struct bfq_data *bfqd,
-+				      struct request *rq1,
-+				      struct request *rq2,
-+				      sector_t last)
-+{
-+	sector_t s1, s2, d1 = 0, d2 = 0;
-+	unsigned long back_max;
-+#define BFQ_RQ1_WRAP	0x01 /* request 1 wraps */
-+#define BFQ_RQ2_WRAP	0x02 /* request 2 wraps */
-+	unsigned int wrap = 0; /* bit mask: requests behind the disk head? */
-+
-+	if (!rq1 || rq1 == rq2)
-+		return rq2;
-+	if (!rq2)
-+		return rq1;
-+
-+	if (rq_is_sync(rq1) && !rq_is_sync(rq2))
-+		return rq1;
-+	else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
-+		return rq2;
-+	if ((rq1->cmd_flags & REQ_META) && !(rq2->cmd_flags & REQ_META))
-+		return rq1;
-+	else if ((rq2->cmd_flags & REQ_META) && !(rq1->cmd_flags & REQ_META))
-+		return rq2;
-+
-+	s1 = blk_rq_pos(rq1);
-+	s2 = blk_rq_pos(rq2);
-+
-+	/*
-+	 * By definition, 1KiB is 2 sectors.
-+	 */
-+	back_max = bfqd->bfq_back_max * 2;
-+
-+	/*
-+	 * Strict one way elevator _except_ in the case where we allow
-+	 * short backward seeks which are biased as twice the cost of a
-+	 * similar forward seek.
-+	 */
-+	if (s1 >= last)
-+		d1 = s1 - last;
-+	else if (s1 + back_max >= last)
-+		d1 = (last - s1) * bfqd->bfq_back_penalty;
-+	else
-+		wrap |= BFQ_RQ1_WRAP;
-+
-+	if (s2 >= last)
-+		d2 = s2 - last;
-+	else if (s2 + back_max >= last)
-+		d2 = (last - s2) * bfqd->bfq_back_penalty;
-+	else
-+		wrap |= BFQ_RQ2_WRAP;
-+
-+	/* Found required data */
-+
-+	/*
-+	 * By doing switch() on the bit mask "wrap" we avoid having to
-+	 * check two variables for all permutations: --> faster!
-+	 */
-+	switch (wrap) {
-+	case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
-+		if (d1 < d2)
-+			return rq1;
-+		else if (d2 < d1)
-+			return rq2;
-+
-+		if (s1 >= s2)
-+			return rq1;
-+		else
-+			return rq2;
-+
-+	case BFQ_RQ2_WRAP:
-+		return rq1;
-+	case BFQ_RQ1_WRAP:
-+		return rq2;
-+	case (BFQ_RQ1_WRAP|BFQ_RQ2_WRAP): /* both rqs wrapped */
-+	default:
-+		/*
-+		 * Since both rqs are wrapped,
-+		 * start with the one that's further behind head
-+		 * (--> only *one* back seek required),
-+		 * since back seek takes more time than forward.
-+		 */
-+		if (s1 <= s2)
-+			return rq1;
-+		else
-+			return rq2;
-+	}
-+}
-+
-+/*
-+ * Async I/O can easily starve sync I/O (both sync reads and sync
-+ * writes), by consuming all tags. Similarly, storms of sync writes,
-+ * such as those that sync(2) may trigger, can starve sync reads.
-+ * Limit depths of async I/O and sync writes so as to counter both
-+ * problems.
-+ */
-+static void bfq_limit_depth(unsigned int op, struct blk_mq_alloc_data *data)
-+{
-+	struct bfq_data *bfqd = data->q->elevator->elevator_data;
-+
-+	if (op_is_sync(op) && !op_is_write(op))
-+		return;
-+
-+	data->shallow_depth =
-+		bfqd->word_depths[!!bfqd->wr_busy_queues][op_is_sync(op)];
-+
-+	bfq_log(bfqd, "wr_busy %d sync %d depth %u",
-+			bfqd->wr_busy_queues, op_is_sync(op),
-+			data->shallow_depth);
-+}
-+
-+static struct bfq_queue *
-+bfq_rq_pos_tree_lookup(struct bfq_data *bfqd, struct rb_root *root,
-+		     sector_t sector, struct rb_node **ret_parent,
-+		     struct rb_node ***rb_link)
-+{
-+	struct rb_node **p, *parent;
-+	struct bfq_queue *bfqq = NULL;
-+
-+	parent = NULL;
-+	p = &root->rb_node;
-+	while (*p) {
-+		struct rb_node **n;
-+
-+		parent = *p;
-+		bfqq = rb_entry(parent, struct bfq_queue, pos_node);
-+
-+		/*
-+		 * Sort strictly based on sector. Smallest to the left,
-+		 * largest to the right.
-+		 */
-+		if (sector > blk_rq_pos(bfqq->next_rq))
-+			n = &(*p)->rb_right;
-+		else if (sector < blk_rq_pos(bfqq->next_rq))
-+			n = &(*p)->rb_left;
-+		else
-+			break;
-+		p = n;
-+		bfqq = NULL;
-+	}
-+
-+	*ret_parent = parent;
-+	if (rb_link)
-+		*rb_link = p;
-+
-+	bfq_log(bfqd, "%llu: returning %d",
-+		(unsigned long long) sector,
-+		bfqq ? bfqq->pid : 0);
-+
-+	return bfqq;
-+}
-+
-+static bool bfq_too_late_for_merging(struct bfq_queue *bfqq)
-+{
-+	return bfqq->service_from_backlogged > 0 &&
-+		time_is_before_jiffies(bfqq->first_IO_time +
-+				       bfq_merge_time_limit);
-+}
-+
-+static void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	struct rb_node **p, *parent;
-+	struct bfq_queue *__bfqq;
-+
-+	if (bfqq->pos_root) {
-+		rb_erase(&bfqq->pos_node, bfqq->pos_root);
-+		bfqq->pos_root = NULL;
-+	}
-+
-+	/*
-+	 * bfqq cannot be merged any longer (see comments in
-+	 * bfq_setup_cooperator): no point in adding bfqq into the
-+	 * position tree.
-+	 */
-+	if (bfq_too_late_for_merging(bfqq))
-+		return;
-+
-+	if (bfq_class_idle(bfqq))
-+		return;
-+	if (!bfqq->next_rq)
-+		return;
-+
-+	bfqq->pos_root = &bfq_bfqq_to_bfqg(bfqq)->rq_pos_tree;
-+	__bfqq = bfq_rq_pos_tree_lookup(bfqd, bfqq->pos_root,
-+			blk_rq_pos(bfqq->next_rq), &parent, &p);
-+	if (!__bfqq) {
-+		rb_link_node(&bfqq->pos_node, parent, p);
-+		rb_insert_color(&bfqq->pos_node, bfqq->pos_root);
-+	} else
-+		bfqq->pos_root = NULL;
-+}
-+
-+/*
-+ * The following function returns true if every queue must receive the
-+ * same share of the throughput (this condition is used when deciding
-+ * whether idling may be disabled, see the comments in the function
-+ * bfq_better_to_idle()).
-+ *
-+ * Such a scenario occurs when:
-+ * 1) all active queues have the same weight,
-+ * 2) all active queues belong to the same I/O-priority class,
-+ * 3) all active groups at the same level in the groups tree have the same
-+ *    weight,
-+ * 4) all active groups at the same level in the groups tree have the same
-+ *    number of children.
-+ *
-+ * Unfortunately, keeping the necessary state for evaluating exactly
-+ * the last two symmetry sub-conditions above would be quite complex
-+ * and time consuming. Therefore this function evaluates, instead,
-+ * only the following stronger three sub-conditions, for which it is
-+ * much easier to maintain the needed state:
-+ * 1) all active queues have the same weight,
-+ * 2) all active queues belong to the same I/O-priority class,
-+ * 3) there are no active groups.
-+ * In particular, the last condition is always true if hierarchical
-+ * support or the cgroups interface are not enabled, thus no state
-+ * needs to be maintained in this case.
-+ */
-+static bool bfq_symmetric_scenario(struct bfq_data *bfqd)
-+{
-+	/*
-+	 * For queue weights to differ, queue_weights_tree must contain
-+	 * at least two nodes.
-+	 */
-+	bool varied_queue_weights = !RB_EMPTY_ROOT(&bfqd->queue_weights_tree) &&
-+		(bfqd->queue_weights_tree.rb_node->rb_left ||
-+		 bfqd->queue_weights_tree.rb_node->rb_right);
-+
-+	bool multiple_classes_busy =
-+		(bfqd->busy_queues[0] && bfqd->busy_queues[1]) ||
-+		(bfqd->busy_queues[0] && bfqd->busy_queues[2]) ||
-+		(bfqd->busy_queues[1] && bfqd->busy_queues[2]);
-+
-+	bfq_log(bfqd, "varied_queue_weights %d mul_classes %d",
-+		varied_queue_weights, multiple_classes_busy);
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	bfq_log(bfqd, "num_groups_with_pending_reqs %u",
-+		bfqd->num_groups_with_pending_reqs);
-+#endif
-+
-+	return !(varied_queue_weights || multiple_classes_busy
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	       || bfqd->num_groups_with_pending_reqs > 0
-+#endif
-+		);
-+}
-+
-+/*
-+ * If the weight-counter tree passed as input contains no counter for
-+ * the weight of the input queue, then add that counter; otherwise just
-+ * increment the existing counter.
-+ *
-+ * Note that weight-counter trees contain few nodes in mostly symmetric
-+ * scenarios. For example, if all queues have the same weight, then the
-+ * weight-counter tree for the queues may contain at most one node.
-+ * This holds even if low_latency is on, because weight-raised queues
-+ * are not inserted in the tree.
-+ * In most scenarios, the rate at which nodes are created/destroyed
-+ * should be low too.
-+ */
-+static void bfq_weights_tree_add(struct bfq_data *bfqd,
-+				 struct bfq_queue *bfqq,
-+				 struct rb_root *root)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+	struct rb_node **new = &(root->rb_node), *parent = NULL;
-+
-+	/*
-+	 * Do not insert if the queue is already associated with a
-+	 * counter, which happens if:
-+	 *   1) a request arrival has caused the queue to become both
-+	 *      non-weight-raised, and hence change its weight, and
-+	 *      backlogged; in this respect, each of the two events
-+	 *      causes an invocation of this function,
-+	 *   2) this is the invocation of this function caused by the
-+	 *      second event. This second invocation is actually useless,
-+	 *      and we handle this fact by exiting immediately. More
-+	 *      efficient or clearer solutions might possibly be adopted.
-+	 */
-+	if (bfqq->weight_counter)
-+		return;
-+
-+	while (*new) {
-+		struct bfq_weight_counter *__counter = container_of(*new,
-+						struct bfq_weight_counter,
-+						weights_node);
-+		parent = *new;
-+
-+		if (entity->weight == __counter->weight) {
-+			bfqq->weight_counter = __counter;
-+			goto inc_counter;
-+		}
-+		if (entity->weight < __counter->weight)
-+			new = &((*new)->rb_left);
-+		else
-+			new = &((*new)->rb_right);
-+	}
-+
-+	bfqq->weight_counter = kzalloc(sizeof(struct bfq_weight_counter),
-+				       GFP_ATOMIC);
-+
-+	/*
-+	 * In the unlucky event of an allocation failure, we just
-+	 * exit. This will cause the weight of queue to not be
-+	 * considered in bfq_symmetric_scenario, which, in its turn,
-+	 * causes the scenario to be deemed wrongly symmetric in case
-+	 * bfqq's weight would have been the only weight making the
-+	 * scenario asymmetric.  On the bright side, no unbalance will
-+	 * however occur when bfqq becomes inactive again (the
-+	 * invocation of this function is triggered by an activation
-+	 * of queue).  In fact, bfq_weights_tree_remove does nothing
-+	 * if !bfqq->weight_counter.
-+	 */
-+	if (unlikely(!bfqq->weight_counter))
-+		return;
-+
-+	bfqq->weight_counter->weight = entity->weight;
-+	rb_link_node(&bfqq->weight_counter->weights_node, parent, new);
-+	rb_insert_color(&bfqq->weight_counter->weights_node, root);
-+
-+inc_counter:
-+	bfqq->weight_counter->num_active++;
-+	bfqq->ref++;
-+
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "refs %d weight %d symmetric %d",
-+				bfqq->ref,
-+				entity->weight,
-+				bfq_symmetric_scenario(bfqd));
-+}
-+
-+/*
-+ * Decrement the weight counter associated with the queue, and, if the
-+ * counter reaches 0, remove the counter from the tree.
-+ * See the comments to the function bfq_weights_tree_add() for considerations
-+ * about overhead.
-+ */
-+static void __bfq_weights_tree_remove(struct bfq_data *bfqd,
-+				      struct bfq_queue *bfqq,
-+				      struct rb_root *root)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+
-+	if (!bfqq->weight_counter)
-+		return;
-+
-+	BUG_ON(RB_EMPTY_ROOT(root));
-+	BUG_ON(bfqq->weight_counter->weight != entity->weight);
-+
-+	BUG_ON(!bfqq->weight_counter->num_active);
-+	bfqq->weight_counter->num_active--;
-+
-+	if (bfqq->weight_counter->num_active > 0)
-+		goto reset_entity_pointer;
-+
-+	rb_erase(&bfqq->weight_counter->weights_node, root);
-+	kfree(bfqq->weight_counter);
-+
-+reset_entity_pointer:
-+	bfqq->weight_counter = NULL;
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		     "refs %d weight %d symmetric %d",
-+		     bfqq->ref,
-+		     entity->weight,
-+		     bfq_symmetric_scenario(bfqd));
-+	bfq_put_queue(bfqq);
-+}
-+
-+/*
-+ * Invoke __bfq_weights_tree_remove on bfqq and decrement the number
-+ * of active groups for each queue's inactive parent entity.
-+ */
-+static void bfq_weights_tree_remove(struct bfq_data *bfqd,
-+				    struct bfq_queue *bfqq)
-+{
-+	struct bfq_entity *entity = bfqq->entity.parent;
-+
-+	for_each_entity(entity) {
-+		struct bfq_sched_data *sd = entity->my_sched_data;
-+
-+		BUG_ON(entity->sched_data == NULL); /*
-+						     * It would mean
-+						     * that this is
-+						     * the root group.
-+						     */
-+
-+		if (sd->next_in_service || sd->in_service_entity) {
-+			BUG_ON(!entity->in_groups_with_pending_reqs);
-+			/*
-+			 * entity is still active, because either
-+			 * next_in_service or in_service_entity is not
-+			 * NULL (see the comments on the definition of
-+			 * next_in_service for details on why
-+			 * in_service_entity must be checked too).
-+			 *
-+			 * As a consequence, its parent entities are
-+			 * active as well, and thus this loop must
-+			 * stop here.
-+			 */
-+			break;
-+		}
-+
-+		BUG_ON(!bfqd->num_groups_with_pending_reqs &&
-+		       entity->in_groups_with_pending_reqs);
-+		/*
-+		 * The decrement of num_groups_with_pending_reqs is
-+		 * not performed immediately upon the deactivation of
-+		 * entity, but it is delayed to when it also happens
-+		 * that the first leaf descendant bfqq of entity gets
-+		 * all its pending requests completed. The following
-+		 * instructions perform this delayed decrement, if
-+		 * needed. See the comments on
-+		 * num_groups_with_pending_reqs for details.
-+		 */
-+		if (entity->in_groups_with_pending_reqs) {
-+			entity->in_groups_with_pending_reqs = false;
-+			bfqd->num_groups_with_pending_reqs--;
-+		}
-+		bfq_log_bfqq(bfqd, bfqq, "num_groups_with_pending_reqs %u",
-+			     bfqd->num_groups_with_pending_reqs);
-+	}
-+
-+	/*
-+	 * Next function is invoked last, because it causes bfqq to be
-+	 * freed if the following holds: bfqq is not in service and
-+	 * has no dispatched request. DO NOT use bfqq after the next
-+	 * function invocation.
-+	 */
-+	__bfq_weights_tree_remove(bfqd, bfqq,
-+				  &bfqd->queue_weights_tree);
-+}
-+
-+/*
-+ * Return expired entry, or NULL to just start from scratch in rbtree.
-+ */
-+static struct request *bfq_check_fifo(struct bfq_queue *bfqq,
-+				      struct request *last)
-+{
-+	struct request *rq;
-+
-+	if (bfq_bfqq_fifo_expire(bfqq))
-+		return NULL;
-+
-+	bfq_mark_bfqq_fifo_expire(bfqq);
-+
-+	rq = rq_entry_fifo(bfqq->fifo.next);
-+
-+	if (rq == last || ktime_get_ns() < rq->fifo_time)
-+		return NULL;
-+
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "returned %p", rq);
-+	BUG_ON(RB_EMPTY_NODE(&rq->rb_node));
-+	return rq;
-+}
-+
-+static struct request *bfq_find_next_rq(struct bfq_data *bfqd,
-+					struct bfq_queue *bfqq,
-+					struct request *last)
-+{
-+	struct rb_node *rbnext = rb_next(&last->rb_node);
-+	struct rb_node *rbprev = rb_prev(&last->rb_node);
-+	struct request *next, *prev = NULL;
-+
-+	BUG_ON(list_empty(&bfqq->fifo));
-+
-+	/* Follow expired path, else get first next available. */
-+	next = bfq_check_fifo(bfqq, last);
-+	if (next) {
-+		BUG_ON(next == last);
-+		return next;
-+	}
-+
-+	BUG_ON(RB_EMPTY_NODE(&last->rb_node));
-+
-+	if (rbprev)
-+		prev = rb_entry_rq(rbprev);
-+
-+	if (rbnext)
-+		next = rb_entry_rq(rbnext);
-+	else {
-+		rbnext = rb_first(&bfqq->sort_list);
-+		if (rbnext && rbnext != &last->rb_node)
-+			next = rb_entry_rq(rbnext);
-+	}
-+
-+	return bfq_choose_req(bfqd, next, prev, blk_rq_pos(last));
-+}
-+
-+/* see the definition of bfq_async_charge_factor for details */
-+static unsigned long bfq_serv_to_charge(struct request *rq,
-+					struct bfq_queue *bfqq)
-+{
-+	if (bfq_bfqq_sync(bfqq) || bfqq->wr_coeff > 1 ||
-+	    !bfq_symmetric_scenario(bfqq->bfqd))
-+		return blk_rq_sectors(rq);
-+
-+	return blk_rq_sectors(rq) * bfq_async_charge_factor;
-+}
-+
-+/**
-+ * bfq_updated_next_req - update the queue after a new next_rq selection.
-+ * @bfqd: the device data the queue belongs to.
-+ * @bfqq: the queue to update.
-+ *
-+ * If the first request of a queue changes we make sure that the queue
-+ * has enough budget to serve at least its first request (if the
-+ * request has grown).  We do this because if the queue has not enough
-+ * budget for its first request, it has to go through two dispatch
-+ * rounds to actually get it dispatched.
-+ */
-+static void bfq_updated_next_req(struct bfq_data *bfqd,
-+				 struct bfq_queue *bfqq)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+	struct bfq_service_tree *st = bfq_entity_service_tree(entity);
-+	struct request *next_rq = bfqq->next_rq;
-+	unsigned long new_budget;
-+
-+	if (!next_rq)
-+		return;
-+
-+	if (bfqq == bfqd->in_service_queue)
-+		/*
-+		 * In order not to break guarantees, budgets cannot be
-+		 * changed after an entity has been selected.
-+		 */
-+		return;
-+
-+	BUG_ON(entity->tree != &st->active);
-+	BUG_ON(entity == entity->sched_data->in_service_entity);
-+
-+	new_budget = max_t(unsigned long,
-+			   max_t(unsigned long, bfqq->max_budget,
-+				 bfq_serv_to_charge(next_rq, bfqq)),
-+			   entity->service);
-+	if (entity->budget != new_budget) {
-+		entity->budget = new_budget;
-+		bfq_log_bfqq(bfqd, bfqq, "new budget %lu",
-+					 new_budget);
-+		bfq_requeue_bfqq(bfqd, bfqq, false);
-+	}
-+}
-+
-+static unsigned int bfq_wr_duration(struct bfq_data *bfqd)
-+{
-+	u64 dur;
-+
-+	if (bfqd->bfq_wr_max_time > 0)
-+		return bfqd->bfq_wr_max_time;
-+
-+	dur = bfqd->rate_dur_prod;
-+	do_div(dur, bfqd->peak_rate);
-+
-+	/*
-+	 * Limit duration between 3 and 25 seconds. The upper limit
-+	 * has been conservatively set after the following worst case:
-+	 * on a QEMU/KVM virtual machine
-+	 * - running in a slow PC
-+	 * - with a virtual disk stacked on a slow low-end 5400rpm HDD
-+	 * - serving a heavy I/O workload, such as the sequential reading
-+	 *   of several files
-+	 * mplayer took 23 seconds to start, if constantly weight-raised.
-+	 *
-+	 * As for higher values than that accomodating the above bad
-+	 * scenario, tests show that higher values would often yield
-+	 * the opposite of the desired result, i.e., would worsen
-+	 * responsiveness by allowing non-interactive applications to
-+	 * preserve weight raising for too long.
-+	 *
-+	 * On the other end, lower values than 3 seconds make it
-+	 * difficult for most interactive tasks to complete their jobs
-+	 * before weight-raising finishes.
-+	 */
-+	return clamp_val(dur, msecs_to_jiffies(3000), msecs_to_jiffies(25000));
-+}
-+
-+/* switch back from soft real-time to interactive weight raising */
-+static void switch_back_to_interactive_wr(struct bfq_queue *bfqq,
-+					  struct bfq_data *bfqd)
-+{
-+	bfqq->wr_coeff = bfqd->bfq_wr_coeff;
-+	bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
-+	bfqq->last_wr_start_finish = bfqq->wr_start_at_switch_to_srt;
-+}
-+
-+static void
-+bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_data *bfqd,
-+		      struct bfq_io_cq *bic, bool bfq_already_existing)
-+{
-+	unsigned int old_wr_coeff;
-+	bool busy = bfq_already_existing && bfq_bfqq_busy(bfqq);
-+
-+	if (bic->saved_has_short_ttime)
-+		bfq_mark_bfqq_has_short_ttime(bfqq);
-+	else
-+		bfq_clear_bfqq_has_short_ttime(bfqq);
-+
-+	if (bic->saved_IO_bound)
-+		bfq_mark_bfqq_IO_bound(bfqq);
-+	else
-+		bfq_clear_bfqq_IO_bound(bfqq);
-+
-+	if (unlikely(busy))
-+		old_wr_coeff = bfqq->wr_coeff;
-+
-+	bfqq->ttime = bic->saved_ttime;
-+	bfqq->wr_coeff = bic->saved_wr_coeff;
-+	bfqq->wr_start_at_switch_to_srt = bic->saved_wr_start_at_switch_to_srt;
-+	BUG_ON(time_is_after_jiffies(bfqq->wr_start_at_switch_to_srt));
-+	bfqq->last_wr_start_finish = bic->saved_last_wr_start_finish;
-+	bfqq->wr_cur_max_time = bic->saved_wr_cur_max_time;
-+	BUG_ON(time_is_after_jiffies(bfqq->last_wr_start_finish));
-+
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		     "bic %p wr_coeff %d start_finish %lu max_time %lu",
-+		     bic, bfqq->wr_coeff, bfqq->last_wr_start_finish,
-+		     bfqq->wr_cur_max_time);
-+
-+	if (bfqq->wr_coeff > 1 && (bfq_bfqq_in_large_burst(bfqq) ||
-+				   time_is_before_jiffies(bfqq->last_wr_start_finish +
-+							  bfqq->wr_cur_max_time))) {
-+		if (bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time &&
-+		    !bfq_bfqq_in_large_burst(bfqq) &&
-+		    time_is_after_eq_jiffies(bfqq->wr_start_at_switch_to_srt +
-+					     bfq_wr_duration(bfqd))) {
-+			switch_back_to_interactive_wr(bfqq, bfqd);
-+			bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			     "switching back to interactive");
-+		} else {
-+			bfqq->wr_coeff = 1;
-+			bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			     "switching off wr (%lu + %lu < %lu)",
-+			     bfqq->last_wr_start_finish, bfqq->wr_cur_max_time,
-+			     jiffies);
-+		}
-+	}
-+
-+	/* make sure weight will be updated, however we got here */
-+	bfqq->entity.prio_changed = 1;
-+
-+	if (likely(!busy))
-+		return;
-+
-+	if (old_wr_coeff == 1 && bfqq->wr_coeff > 1) {
-+		bfqd->wr_busy_queues++;
-+		BUG_ON(bfqd->wr_busy_queues > bfq_tot_busy_queues(bfqd));
-+	} else if (old_wr_coeff > 1 && bfqq->wr_coeff == 1) {
-+		bfqd->wr_busy_queues--;
-+		BUG_ON(bfqd->wr_busy_queues < 0);
-+	}
-+}
-+
-+static int bfqq_process_refs(struct bfq_queue *bfqq)
-+{
-+	int process_refs, io_refs;
-+
-+	lockdep_assert_held(&bfqq->bfqd->lock);
-+
-+	io_refs = bfqq->allocated;
-+	process_refs = bfqq->ref - io_refs - bfqq->entity.on_st -
-+		(bfqq->weight_counter != NULL);
-+	BUG_ON(process_refs < 0);
-+	return process_refs;
-+}
-+
-+/* Empty burst list and add just bfqq (see comments to bfq_handle_burst) */
-+static void bfq_reset_burst_list(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	struct bfq_queue *item;
-+	struct hlist_node *n;
-+
-+	hlist_for_each_entry_safe(item, n, &bfqd->burst_list, burst_list_node)
-+		hlist_del_init(&item->burst_list_node);
-+	hlist_add_head(&bfqq->burst_list_node, &bfqd->burst_list);
-+	bfqd->burst_size = 1;
-+	bfqd->burst_parent_entity = bfqq->entity.parent;
-+}
-+
-+/* Add bfqq to the list of queues in current burst (see bfq_handle_burst) */
-+static void bfq_add_to_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	/* Increment burst size to take into account also bfqq */
-+	bfqd->burst_size++;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "%d", bfqd->burst_size);
-+
-+	BUG_ON(bfqd->burst_size > bfqd->bfq_large_burst_thresh);
-+
-+	if (bfqd->burst_size == bfqd->bfq_large_burst_thresh) {
-+		struct bfq_queue *pos, *bfqq_item;
-+		struct hlist_node *n;
-+
-+		/*
-+		 * Enough queues have been activated shortly after each
-+		 * other to consider this burst as large.
-+		 */
-+		bfqd->large_burst = true;
-+		bfq_log_bfqq(bfqd, bfqq, "large burst started");
-+
-+		/*
-+		 * We can now mark all queues in the burst list as
-+		 * belonging to a large burst.
-+		 */
-+		hlist_for_each_entry(bfqq_item, &bfqd->burst_list,
-+				     burst_list_node) {
-+			bfq_mark_bfqq_in_large_burst(bfqq_item);
-+			bfq_log_bfqq(bfqd, bfqq_item, "marked in large burst");
-+		}
-+		bfq_mark_bfqq_in_large_burst(bfqq);
-+		bfq_log_bfqq(bfqd, bfqq, "marked in large burst");
-+
-+		/*
-+		 * From now on, and until the current burst finishes, any
-+		 * new queue being activated shortly after the last queue
-+		 * was inserted in the burst can be immediately marked as
-+		 * belonging to a large burst. So the burst list is not
-+		 * needed any more. Remove it.
-+		 */
-+		hlist_for_each_entry_safe(pos, n, &bfqd->burst_list,
-+					  burst_list_node)
-+			hlist_del_init(&pos->burst_list_node);
-+	} else /*
-+		* Burst not yet large: add bfqq to the burst list. Do
-+		* not increment the ref counter for bfqq, because bfqq
-+		* is removed from the burst list before freeing bfqq
-+		* in put_queue.
-+		*/
-+		hlist_add_head(&bfqq->burst_list_node, &bfqd->burst_list);
-+}
-+
-+/*
-+ * If many queues belonging to the same group happen to be created
-+ * shortly after each other, then the processes associated with these
-+ * queues have typically a common goal. In particular, bursts of queue
-+ * creations are usually caused by services or applications that spawn
-+ * many parallel threads/processes. Examples are systemd during boot,
-+ * or git grep. To help these processes get their job done as soon as
-+ * possible, it is usually better to not grant either weight-raising
-+ * or device idling to their queues.
-+ *
-+ * In this comment we describe, firstly, the reasons why this fact
-+ * holds, and, secondly, the next function, which implements the main
-+ * steps needed to properly mark these queues so that they can then be
-+ * treated in a different way.
-+ *
-+ * The above services or applications benefit mostly from a high
-+ * throughput: the quicker the requests of the activated queues are
-+ * cumulatively served, the sooner the target job of these queues gets
-+ * completed. As a consequence, weight-raising any of these queues,
-+ * which also implies idling the device for it, is almost always
-+ * counterproductive. In most cases it just lowers throughput.
-+ *
-+ * On the other hand, a burst of queue creations may be caused also by
-+ * the start of an application that does not consist of a lot of
-+ * parallel I/O-bound threads. In fact, with a complex application,
-+ * several short processes may need to be executed to start-up the
-+ * application. In this respect, to start an application as quickly as
-+ * possible, the best thing to do is in any case to privilege the I/O
-+ * related to the application with respect to all other
-+ * I/O. Therefore, the best strategy to start as quickly as possible
-+ * an application that causes a burst of queue creations is to
-+ * weight-raise all the queues created during the burst. This is the
-+ * exact opposite of the best strategy for the other type of bursts.
-+ *
-+ * In the end, to take the best action for each of the two cases, the
-+ * two types of bursts need to be distinguished. Fortunately, this
-+ * seems relatively easy, by looking at the sizes of the bursts. In
-+ * particular, we found a threshold such that only bursts with a
-+ * larger size than that threshold are apparently caused by
-+ * services or commands such as systemd or git grep. For brevity,
-+ * hereafter we call just 'large' these bursts. BFQ *does not*
-+ * weight-raise queues whose creation occurs in a large burst. In
-+ * addition, for each of these queues BFQ performs or does not perform
-+ * idling depending on which choice boosts the throughput more. The
-+ * exact choice depends on the device and request pattern at
-+ * hand.
-+ *
-+ * Unfortunately, false positives may occur while an interactive task
-+ * is starting (e.g., an application is being started). The
-+ * consequence is that the queues associated with the task do not
-+ * enjoy weight raising as expected. Fortunately these false positives
-+ * are very rare. They typically occur if some service happens to
-+ * start doing I/O exactly when the interactive task starts.
-+ *
-+ * Turning back to the next function, it implements all the steps
-+ * needed to detect the occurrence of a large burst and to properly
-+ * mark all the queues belonging to it (so that they can then be
-+ * treated in a different way). This goal is achieved by maintaining a
-+ * "burst list" that holds, temporarily, the queues that belong to the
-+ * burst in progress. The list is then used to mark these queues as
-+ * belonging to a large burst if the burst does become large. The main
-+ * steps are the following.
-+ *
-+ * . when the very first queue is created, the queue is inserted into the
-+ *   list (as it could be the first queue in a possible burst)
-+ *
-+ * . if the current burst has not yet become large, and a queue Q that does
-+ *   not yet belong to the burst is activated shortly after the last time
-+ *   at which a new queue entered the burst list, then the function appends
-+ *   Q to the burst list
-+ *
-+ * . if, as a consequence of the previous step, the burst size reaches
-+ *   the large-burst threshold, then
-+ *
-+ *     . all the queues in the burst list are marked as belonging to a
-+ *       large burst
-+ *
-+ *     . the burst list is deleted; in fact, the burst list already served
-+ *       its purpose (keeping temporarily track of the queues in a burst,
-+ *       so as to be able to mark them as belonging to a large burst in the
-+ *       previous sub-step), and now is not needed any more
-+ *
-+ *     . the device enters a large-burst mode
-+ *
-+ * . if a queue Q that does not belong to the burst is created while
-+ *   the device is in large-burst mode and shortly after the last time
-+ *   at which a queue either entered the burst list or was marked as
-+ *   belonging to the current large burst, then Q is immediately marked
-+ *   as belonging to a large burst.
-+ *
-+ * . if a queue Q that does not belong to the burst is created a while
-+ *   later, i.e., not shortly after, than the last time at which a queue
-+ *   either entered the burst list or was marked as belonging to the
-+ *   current large burst, then the current burst is deemed as finished and:
-+ *
-+ *        . the large-burst mode is reset if set
-+ *
-+ *        . the burst list is emptied
-+ *
-+ *        . Q is inserted in the burst list, as Q may be the first queue
-+ *          in a possible new burst (then the burst list contains just Q
-+ *          after this step).
-+ */
-+static void bfq_handle_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	/*
-+	 * If bfqq is already in the burst list or is part of a large
-+	 * burst, or finally has just been split, then there is
-+	 * nothing else to do.
-+	 */
-+	if (!hlist_unhashed(&bfqq->burst_list_node) ||
-+	    bfq_bfqq_in_large_burst(bfqq) ||
-+	    time_is_after_eq_jiffies(bfqq->split_time +
-+				     msecs_to_jiffies(10)))
-+		return;
-+
-+	/*
-+	 * If bfqq's creation happens late enough, or bfqq belongs to
-+	 * a different group than the burst group, then the current
-+	 * burst is finished, and related data structures must be
-+	 * reset.
-+	 *
-+	 * In this respect, consider the special case where bfqq is
-+	 * the very first queue created after BFQ is selected for this
-+	 * device. In this case, last_ins_in_burst and
-+	 * burst_parent_entity are not yet significant when we get
-+	 * here. But it is easy to verify that, whether or not the
-+	 * following condition is true, bfqq will end up being
-+	 * inserted into the burst list. In particular the list will
-+	 * happen to contain only bfqq. And this is exactly what has
-+	 * to happen, as bfqq may be the first queue of the first
-+	 * burst.
-+	 */
-+	if (time_is_before_jiffies(bfqd->last_ins_in_burst +
-+	    bfqd->bfq_burst_interval) ||
-+	    bfqq->entity.parent != bfqd->burst_parent_entity) {
-+		bfqd->large_burst = false;
-+		bfq_reset_burst_list(bfqd, bfqq);
-+		bfq_log_bfqq(bfqd, bfqq,
-+			"late activation or different group");
-+		goto end;
-+	}
-+
-+	/*
-+	 * If we get here, then bfqq is being activated shortly after the
-+	 * last queue. So, if the current burst is also large, we can mark
-+	 * bfqq as belonging to this large burst immediately.
-+	 */
-+	if (bfqd->large_burst) {
-+		bfq_log_bfqq(bfqd, bfqq, "marked in burst");
-+		bfq_mark_bfqq_in_large_burst(bfqq);
-+		goto end;
-+	}
-+
-+	/*
-+	 * If we get here, then a large-burst state has not yet been
-+	 * reached, but bfqq is being activated shortly after the last
-+	 * queue. Then we add bfqq to the burst.
-+	 */
-+	bfq_add_to_burst(bfqd, bfqq);
-+end:
-+	/*
-+	 * At this point, bfqq either has been added to the current
-+	 * burst or has caused the current burst to terminate and a
-+	 * possible new burst to start. In particular, in the second
-+	 * case, bfqq has become the first queue in the possible new
-+	 * burst.  In both cases last_ins_in_burst needs to be moved
-+	 * forward.
-+	 */
-+	bfqd->last_ins_in_burst = jiffies;
-+
-+}
-+
-+static int bfq_bfqq_budget_left(struct bfq_queue *bfqq)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+
-+	if (entity->budget < entity->service) {
-+		pr_crit("budget %d service %d\n",
-+			entity->budget, entity->service);
-+		BUG();
-+	}
-+	return entity->budget - entity->service;
-+}
-+
-+/*
-+ * If enough samples have been computed, return the current max budget
-+ * stored in bfqd, which is dynamically updated according to the
-+ * estimated disk peak rate; otherwise return the default max budget
-+ */
-+static int bfq_max_budget(struct bfq_data *bfqd)
-+{
-+	if (bfqd->budgets_assigned < bfq_stats_min_budgets)
-+		return bfq_default_max_budget;
-+	else
-+		return bfqd->bfq_max_budget;
-+}
-+
-+/*
-+ * Return min budget, which is a fraction of the current or default
-+ * max budget (trying with 1/32)
-+ */
-+static int bfq_min_budget(struct bfq_data *bfqd)
-+{
-+	if (bfqd->budgets_assigned < bfq_stats_min_budgets)
-+		return bfq_default_max_budget / 32;
-+	else
-+		return bfqd->bfq_max_budget / 32;
-+}
-+
-+static void bfq_bfqq_expire(struct bfq_data *bfqd,
-+			    struct bfq_queue *bfqq,
-+			    bool compensate,
-+			    enum bfqq_expiration reason);
-+
-+/*
-+ * The next function, invoked after the input queue bfqq switches from
-+ * idle to busy, updates the budget of bfqq. The function also tells
-+ * whether the in-service queue should be expired, by returning
-+ * true. The purpose of expiring the in-service queue is to give bfqq
-+ * the chance to possibly preempt the in-service queue, and the reason
-+ * for preempting the in-service queue is to achieve one of the two
-+ * goals below.
-+ *
-+ * 1. Guarantee to bfqq its reserved bandwidth even if bfqq has
-+ * expired because it has remained idle. In particular, bfqq may have
-+ * expired for one of the following two reasons:
-+ *
-+ * - BFQ_BFQQ_NO_MORE_REQUEST bfqq did not enjoy any device idling and
-+ *   did not make it to issue a new request before its last request
-+ *   was served;
-+ *
-+ * - BFQ_BFQQ_TOO_IDLE bfqq did enjoy device idling, but did not issue
-+ *   a new request before the expiration of the idling-time.
-+ *
-+ * Even if bfqq has expired for one of the above reasons, the process
-+ * associated with the queue may be however issuing requests greedily,
-+ * and thus be sensitive to the bandwidth it receives (bfqq may have
-+ * remained idle for other reasons: CPU high load, bfqq not enjoying
-+ * idling, I/O throttling somewhere in the path from the process to
-+ * the I/O scheduler, ...). But if, after every expiration for one of
-+ * the above two reasons, bfqq has to wait for the service of at least
-+ * one full budget of another queue before being served again, then
-+ * bfqq is likely to get a much lower bandwidth or resource time than
-+ * its reserved ones. To address this issue, two countermeasures need
-+ * to be taken.
-+ *
-+ * First, the budget and the timestamps of bfqq need to be updated in
-+ * a special way on bfqq reactivation: they need to be updated as if
-+ * bfqq did not remain idle and did not expire. In fact, if they are
-+ * computed as if bfqq expired and remained idle until reactivation,
-+ * then the process associated with bfqq is treated as if, instead of
-+ * being greedy, it stopped issuing requests when bfqq remained idle,
-+ * and restarts issuing requests only on this reactivation. In other
-+ * words, the scheduler does not help the process recover the "service
-+ * hole" between bfqq expiration and reactivation. As a consequence,
-+ * the process receives a lower bandwidth than its reserved one. In
-+ * contrast, to recover this hole, the budget must be updated as if
-+ * bfqq was not expired at all before this reactivation, i.e., it must
-+ * be set to the value of the remaining budget when bfqq was
-+ * expired. Along the same line, timestamps need to be assigned the
-+ * value they had the last time bfqq was selected for service, i.e.,
-+ * before last expiration. Thus timestamps need to be back-shifted
-+ * with respect to their normal computation (see [1] for more details
-+ * on this tricky aspect).
-+ *
-+ * Secondly, to allow the process to recover the hole, the in-service
-+ * queue must be expired too, to give bfqq the chance to preempt it
-+ * immediately. In fact, if bfqq has to wait for a full budget of the
-+ * in-service queue to be completed, then it may become impossible to
-+ * let the process recover the hole, even if the back-shifted
-+ * timestamps of bfqq are lower than those of the in-service queue. If
-+ * this happens for most or all of the holes, then the process may not
-+ * receive its reserved bandwidth. In this respect, it is worth noting
-+ * that, being the service of outstanding requests unpreemptible, a
-+ * little fraction of the holes may however be unrecoverable, thereby
-+ * causing a little loss of bandwidth.
-+ *
-+ * The last important point is detecting whether bfqq does need this
-+ * bandwidth recovery. In this respect, the next function deems the
-+ * process associated with bfqq greedy, and thus allows it to recover
-+ * the hole, if: 1) the process is waiting for the arrival of a new
-+ * request (which implies that bfqq expired for one of the above two
-+ * reasons), and 2) such a request has arrived soon. The first
-+ * condition is controlled through the flag non_blocking_wait_rq,
-+ * while the second through the flag arrived_in_time. If both
-+ * conditions hold, then the function computes the budget in the
-+ * above-described special way, and signals that the in-service queue
-+ * should be expired. Timestamp back-shifting is done later in
-+ * __bfq_activate_entity.
-+ *
-+ * 2. Reduce latency. Even if timestamps are not backshifted to let
-+ * the process associated with bfqq recover a service hole, bfqq may
-+ * however happen to have, after being (re)activated, a lower finish
-+ * timestamp than the in-service queue.  That is, the next budget of
-+ * bfqq may have to be completed before the one of the in-service
-+ * queue. If this is the case, then preempting the in-service queue
-+ * allows this goal to be achieved, apart from the unpreemptible,
-+ * outstanding requests mentioned above.
-+ *
-+ * Unfortunately, regardless of which of the above two goals one wants
-+ * to achieve, service trees need first to be updated to know whether
-+ * the in-service queue must be preempted. To have service trees
-+ * correctly updated, the in-service queue must be expired and
-+ * rescheduled, and bfqq must be scheduled too. This is one of the
-+ * most costly operations (in future versions, the scheduling
-+ * mechanism may be re-designed in such a way to make it possible to
-+ * know whether preemption is needed without needing to update service
-+ * trees). In addition, queue preemptions almost always cause random
-+ * I/O, and thus loss of throughput. Because of these facts, the next
-+ * function adopts the following simple scheme to avoid both costly
-+ * operations and too frequent preemptions: it requests the expiration
-+ * of the in-service queue (unconditionally) only for queues that need
-+ * to recover a hole, or that either are weight-raised or deserve to
-+ * be weight-raised.
-+ */
-+static bool bfq_bfqq_update_budg_for_activation(struct bfq_data *bfqd,
-+						struct bfq_queue *bfqq,
-+						bool arrived_in_time,
-+						bool wr_or_deserves_wr)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+
-+	/*
-+	 * In the next compound condition, we check also whether there
-+	 * is some budget left, because otherwise there is no point in
-+	 * trying to go on serving bfqq with this same budget: bfqq
-+	 * would be expired immediately after being selected for
-+	 * service. This would only cause useless overhead.
-+	 */
-+	if (bfq_bfqq_non_blocking_wait_rq(bfqq) && arrived_in_time &&
-+	    bfq_bfqq_budget_left(bfqq) > 0) {
-+		/*
-+		 * We do not clear the flag non_blocking_wait_rq here, as
-+		 * the latter is used in bfq_activate_bfqq to signal
-+		 * that timestamps need to be back-shifted (and is
-+		 * cleared right after).
-+		 */
-+
-+		/*
-+		 * In next assignment we rely on that either
-+		 * entity->service or entity->budget are not updated
-+		 * on expiration if bfqq is empty (see
-+		 * __bfq_bfqq_recalc_budget). Thus both quantities
-+		 * remain unchanged after such an expiration, and the
-+		 * following statement therefore assigns to
-+		 * entity->budget the remaining budget on such an
-+		 * expiration.
-+		 */
-+		BUG_ON(bfqq->max_budget < 0);
-+		entity->budget = min_t(unsigned long,
-+				       bfq_bfqq_budget_left(bfqq),
-+				       bfqq->max_budget);
-+
-+		BUG_ON(entity->budget < 0);
-+
-+		/*
-+		 * At this point, we have used entity->service to get
-+		 * the budget left (needed for updating
-+		 * entity->budget). Thus we finally can, and have to,
-+		 * reset entity->service. The latter must be reset
-+		 * because bfqq would otherwise be charged again for
-+		 * the service it has received during its previous
-+		 * service slot(s).
-+		 */
-+		entity->service = 0;
-+
-+		return true;
-+	}
-+
-+	/*
-+	 * We can finally complete expiration, by setting service to 0.
-+	 */
-+	entity->service = 0;
-+	BUG_ON(bfqq->max_budget < 0);
-+	entity->budget = max_t(unsigned long, bfqq->max_budget,
-+			       bfq_serv_to_charge(bfqq->next_rq, bfqq));
-+	BUG_ON(entity->budget < 0);
-+
-+	bfq_clear_bfqq_non_blocking_wait_rq(bfqq);
-+	return wr_or_deserves_wr;
-+}
-+
-+/*
-+ * Return the farthest past time instant according to jiffies
-+ * macros.
-+ */
-+static unsigned long bfq_smallest_from_now(void)
-+{
-+	return jiffies - MAX_JIFFY_OFFSET;
-+}
-+
-+static void bfq_update_bfqq_wr_on_rq_arrival(struct bfq_data *bfqd,
-+					     struct bfq_queue *bfqq,
-+					     unsigned int old_wr_coeff,
-+					     bool wr_or_deserves_wr,
-+					     bool interactive,
-+					     bool in_burst,
-+					     bool soft_rt)
-+{
-+	if (old_wr_coeff == 1 && wr_or_deserves_wr) {
-+		/* start a weight-raising period */
-+		if (interactive) {
-+			bfqq->service_from_wr = 0;
-+			bfqq->wr_coeff = bfqd->bfq_wr_coeff;
-+			bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
-+		} else {
-+			/*
-+			 * No interactive weight raising in progress
-+			 * here: assign minus infinity to
-+			 * wr_start_at_switch_to_srt, to make sure
-+			 * that, at the end of the soft-real-time
-+			 * weight raising periods that is starting
-+			 * now, no interactive weight-raising period
-+			 * may be wrongly considered as still in
-+			 * progress (and thus actually started by
-+			 * mistake).
-+			 */
-+			bfqq->wr_start_at_switch_to_srt =
-+				bfq_smallest_from_now();
-+			bfqq->wr_coeff = bfqd->bfq_wr_coeff *
-+				BFQ_SOFTRT_WEIGHT_FACTOR;
-+			bfqq->wr_cur_max_time =
-+				bfqd->bfq_wr_rt_max_time;
-+		}
-+		/*
-+		 * If needed, further reduce budget to make sure it is
-+		 * close to bfqq's backlog, so as to reduce the
-+		 * scheduling-error component due to a too large
-+		 * budget. Do not care about throughput consequences,
-+		 * but only about latency. Finally, do not assign a
-+		 * too small budget either, to avoid increasing
-+		 * latency by causing too frequent expirations.
-+		 */
-+		bfqq->entity.budget = min_t(unsigned long,
-+					    bfqq->entity.budget,
-+					    2 * bfq_min_budget(bfqd));
-+
-+		bfq_log_bfqq(bfqd, bfqq,
-+			     "wrais starting at %lu, rais_max_time %u",
-+			     jiffies,
-+			     jiffies_to_msecs(bfqq->wr_cur_max_time));
-+	} else if (old_wr_coeff > 1) {
-+		if (interactive) { /* update wr coeff and duration */
-+			bfqq->wr_coeff = bfqd->bfq_wr_coeff;
-+			bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
-+		} else if (in_burst) {
-+			bfqq->wr_coeff = 1;
-+			bfq_log_bfqq(bfqd, bfqq,
-+				     "wrais ending at %lu, rais_max_time %u",
-+				     jiffies,
-+				     jiffies_to_msecs(bfqq->
-+						      wr_cur_max_time));
-+		} else if (soft_rt) {
-+			/*
-+			 * The application is now or still meeting the
-+			 * requirements for being deemed soft rt.  We
-+			 * can then correctly and safely (re)charge
-+			 * the weight-raising duration for the
-+			 * application with the weight-raising
-+			 * duration for soft rt applications.
-+			 *
-+			 * In particular, doing this recharge now, i.e.,
-+			 * before the weight-raising period for the
-+			 * application finishes, reduces the probability
-+			 * of the following negative scenario:
-+			 * 1) the weight of a soft rt application is
-+			 *    raised at startup (as for any newly
-+			 *    created application),
-+			 * 2) since the application is not interactive,
-+			 *    at a certain time weight-raising is
-+			 *    stopped for the application,
-+			 * 3) at that time the application happens to
-+			 *    still have pending requests, and hence
-+			 *    is destined to not have a chance to be
-+			 *    deemed soft rt before these requests are
-+			 *    completed (see the comments to the
-+			 *    function bfq_bfqq_softrt_next_start()
-+			 *    for details on soft rt detection),
-+			 * 4) these pending requests experience a high
-+			 *    latency because the application is not
-+			 *    weight-raised while they are pending.
-+			 */
-+			if (bfqq->wr_cur_max_time !=
-+				bfqd->bfq_wr_rt_max_time) {
-+				bfqq->wr_start_at_switch_to_srt =
-+					bfqq->last_wr_start_finish;
-+                BUG_ON(time_is_after_jiffies(bfqq->last_wr_start_finish));
-+
-+				bfqq->wr_cur_max_time =
-+					bfqd->bfq_wr_rt_max_time;
-+				bfqq->wr_coeff = bfqd->bfq_wr_coeff *
-+					BFQ_SOFTRT_WEIGHT_FACTOR;
-+				bfq_log_bfqq(bfqd, bfqq,
-+					     "switching to soft_rt wr");
-+			} else
-+				bfq_log_bfqq(bfqd, bfqq,
-+					"moving forward soft_rt wr duration");
-+			bfqq->last_wr_start_finish = jiffies;
-+		}
-+	}
-+}
-+
-+static bool bfq_bfqq_idle_for_long_time(struct bfq_data *bfqd,
-+					struct bfq_queue *bfqq)
-+{
-+	return bfqq->dispatched == 0 &&
-+		time_is_before_jiffies(
-+			bfqq->budget_timeout +
-+			bfqd->bfq_wr_min_idle_time);
-+}
-+
-+static void bfq_bfqq_handle_idle_busy_switch(struct bfq_data *bfqd,
-+					     struct bfq_queue *bfqq,
-+					     int old_wr_coeff,
-+					     struct request *rq,
-+					     bool *interactive)
-+{
-+	bool soft_rt, in_burst,	wr_or_deserves_wr,
-+		bfqq_wants_to_preempt,
-+		idle_for_long_time = bfq_bfqq_idle_for_long_time(bfqd, bfqq),
-+		/*
-+		 * See the comments on
-+		 * bfq_bfqq_update_budg_for_activation for
-+		 * details on the usage of the next variable.
-+		 */
-+		arrived_in_time =  ktime_get_ns() <=
-+			bfqq->ttime.last_end_request +
-+			bfqd->bfq_slice_idle * 3;
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+		     "bfq_add_request non-busy: "
-+		     "jiffies %lu, in_time %d, idle_long %d busyw %d "
-+		     "wr_coeff %u",
-+		     jiffies, arrived_in_time,
-+		     idle_for_long_time,
-+		     bfq_bfqq_non_blocking_wait_rq(bfqq),
-+		     old_wr_coeff);
-+
-+	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
-+
-+	BUG_ON(bfqq == bfqd->in_service_queue);
-+
-+	/*
-+	 * bfqq deserves to be weight-raised if:
-+	 * - it is sync,
-+	 * - it does not belong to a large burst,
-+	 * - it has been idle for enough time or is soft real-time,
-+	 * - is linked to a bfq_io_cq (it is not shared in any sense)
-+	 */
-+	in_burst = bfq_bfqq_in_large_burst(bfqq);
-+	soft_rt = bfqd->bfq_wr_max_softrt_rate > 0 &&
-+		!in_burst &&
-+		time_is_before_jiffies(bfqq->soft_rt_next_start) &&
-+		bfqq->dispatched == 0;
-+	*interactive =
-+		!in_burst &&
-+		idle_for_long_time;
-+	wr_or_deserves_wr = bfqd->low_latency &&
-+		(bfqq->wr_coeff > 1 ||
-+		 (bfq_bfqq_sync(bfqq) &&
-+		  bfqq->bic && (*interactive || soft_rt)));
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+		     "bfq_add_request: "
-+		     "in_burst %d, "
-+		     "soft_rt %d (next %lu), inter %d, bic %p",
-+		     bfq_bfqq_in_large_burst(bfqq), soft_rt,
-+		     bfqq->soft_rt_next_start,
-+		     *interactive,
-+		     bfqq->bic);
-+
-+	/*
-+	 * Using the last flag, update budget and check whether bfqq
-+	 * may want to preempt the in-service queue.
-+	 */
-+	bfqq_wants_to_preempt =
-+		bfq_bfqq_update_budg_for_activation(bfqd, bfqq,
-+						    arrived_in_time,
-+						    wr_or_deserves_wr);
-+
-+	/*
-+	 * If bfqq happened to be activated in a burst, but has been
-+	 * idle for much more than an interactive queue, then we
-+	 * assume that, in the overall I/O initiated in the burst, the
-+	 * I/O associated with bfqq is finished. So bfqq does not need
-+	 * to be treated as a queue belonging to a burst
-+	 * anymore. Accordingly, we reset bfqq's in_large_burst flag
-+	 * if set, and remove bfqq from the burst list if it's
-+	 * there. We do not decrement burst_size, because the fact
-+	 * that bfqq does not need to belong to the burst list any
-+	 * more does not invalidate the fact that bfqq was created in
-+	 * a burst.
-+	 */
-+	if (likely(!bfq_bfqq_just_created(bfqq)) &&
-+	    idle_for_long_time &&
-+	    time_is_before_jiffies(
-+		    bfqq->budget_timeout +
-+		    msecs_to_jiffies(10000))) {
-+		hlist_del_init(&bfqq->burst_list_node);
-+		bfq_clear_bfqq_in_large_burst(bfqq);
-+	}
-+
-+	bfq_clear_bfqq_just_created(bfqq);
-+
-+	if (!bfq_bfqq_IO_bound(bfqq)) {
-+		if (arrived_in_time) {
-+			bfqq->requests_within_timer++;
-+			if (bfqq->requests_within_timer >=
-+			    bfqd->bfq_requests_within_timer)
-+				bfq_mark_bfqq_IO_bound(bfqq);
-+		} else
-+			bfqq->requests_within_timer = 0;
-+		bfq_log_bfqq(bfqd, bfqq, "requests in time %d",
-+			     bfqq->requests_within_timer);
-+	}
-+
-+	if (bfqd->low_latency) {
-+		if (unlikely(time_is_after_jiffies(bfqq->split_time)))
-+			/* wraparound */
-+			bfqq->split_time =
-+				jiffies - bfqd->bfq_wr_min_idle_time - 1;
-+
-+		if (time_is_before_jiffies(bfqq->split_time +
-+					   bfqd->bfq_wr_min_idle_time)) {
-+			bfq_update_bfqq_wr_on_rq_arrival(bfqd, bfqq,
-+							 old_wr_coeff,
-+							 wr_or_deserves_wr,
-+							 *interactive,
-+							 in_burst,
-+							 soft_rt);
-+
-+			if (old_wr_coeff != bfqq->wr_coeff)
-+				bfqq->entity.prio_changed = 1;
-+		}
-+	}
-+
-+	bfqq->last_idle_bklogged = jiffies;
-+	bfqq->service_from_backlogged = 0;
-+	bfq_clear_bfqq_softrt_update(bfqq);
-+
-+	bfq_add_bfqq_busy(bfqd, bfqq);
-+
-+	/*
-+	 * Expire in-service queue only if preemption may be needed
-+	 * for guarantees. In this respect, the function
-+	 * next_queue_may_preempt just checks a simple, necessary
-+	 * condition, and not a sufficient condition based on
-+	 * timestamps. In fact, for the latter condition to be
-+	 * evaluated, timestamps would need first to be updated, and
-+	 * this operation is quite costly (see the comments on the
-+	 * function bfq_bfqq_update_budg_for_activation).
-+	 */
-+	if (bfqd->in_service_queue && bfqq_wants_to_preempt &&
-+	    bfqd->in_service_queue->wr_coeff < bfqq->wr_coeff &&
-+	    next_queue_may_preempt(bfqd)) {
-+		struct bfq_queue *in_serv =
-+			bfqd->in_service_queue;
-+		BUG_ON(in_serv == bfqq);
-+
-+		bfq_bfqq_expire(bfqd, bfqd->in_service_queue,
-+				false, BFQ_BFQQ_PREEMPTED);
-+	}
-+}
-+
-+static void bfq_add_request(struct request *rq)
-+{
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq);
-+	struct bfq_data *bfqd = bfqq->bfqd;
-+	struct request *next_rq, *prev;
-+	unsigned int old_wr_coeff = bfqq->wr_coeff;
-+	bool interactive = false;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "size %u %s",
-+		     blk_rq_sectors(rq), rq_is_sync(rq) ? "S" : "A");
-+
-+	if (bfqq->wr_coeff > 1) /* queue is being weight-raised */
-+		bfq_log_bfqq(bfqd, bfqq,
-+			"raising period dur %u/%u msec, old coeff %u, w %d(%d)",
-+			jiffies_to_msecs(jiffies - bfqq->last_wr_start_finish),
-+			jiffies_to_msecs(bfqq->wr_cur_max_time),
-+			bfqq->wr_coeff,
-+			bfqq->entity.weight, bfqq->entity.orig_weight);
-+
-+	bfqq->queued[rq_is_sync(rq)]++;
-+	bfqd->queued++;
-+
-+	BUG_ON(!RQ_BFQQ(rq));
-+	BUG_ON(RQ_BFQQ(rq) != bfqq);
-+	WARN_ON(blk_rq_sectors(rq) == 0);
-+
-+	elv_rb_add(&bfqq->sort_list, rq);
-+
-+	/*
-+	 * Check if this request is a better next-to-serve candidate.
-+	 */
-+	prev = bfqq->next_rq;
-+	next_rq = bfq_choose_req(bfqd, bfqq->next_rq, rq, bfqd->last_position);
-+	BUG_ON(!next_rq);
-+	BUG_ON(!RQ_BFQQ(next_rq));
-+	BUG_ON(RQ_BFQQ(next_rq) != bfqq);
-+	bfqq->next_rq = next_rq;
-+
-+	/*
-+	 * Adjust priority tree position, if next_rq changes.
-+	 */
-+	if (prev != bfqq->next_rq)
-+		bfq_pos_tree_add_move(bfqd, bfqq);
-+
-+	if (!bfq_bfqq_busy(bfqq)) /* switching to busy ... */
-+		bfq_bfqq_handle_idle_busy_switch(bfqd, bfqq, old_wr_coeff,
-+						 rq, &interactive);
-+	else {
-+		if (bfqd->low_latency && old_wr_coeff == 1 && !rq_is_sync(rq) &&
-+		    time_is_before_jiffies(
-+				bfqq->last_wr_start_finish +
-+				bfqd->bfq_wr_min_inter_arr_async)) {
-+			bfqq->wr_coeff = bfqd->bfq_wr_coeff;
-+			bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
-+
-+			bfqd->wr_busy_queues++;
-+			BUG_ON(bfqd->wr_busy_queues > bfq_tot_busy_queues(bfqd));
-+			bfqq->entity.prio_changed = 1;
-+			bfq_log_bfqq(bfqd, bfqq,
-+				     "non-idle wrais starting, "
-+				     "wr_max_time %u wr_busy %d",
-+				     jiffies_to_msecs(bfqq->wr_cur_max_time),
-+				     bfqd->wr_busy_queues);
-+		}
-+		if (prev != bfqq->next_rq)
-+			bfq_updated_next_req(bfqd, bfqq);
-+	}
-+
-+	/*
-+	 * Assign jiffies to last_wr_start_finish in the following
-+	 * cases:
-+	 *
-+	 * . if bfqq is not going to be weight-raised, because, for
-+	 *   non weight-raised queues, last_wr_start_finish stores the
-+	 *   arrival time of the last request; as of now, this piece
-+	 *   of information is used only for deciding whether to
-+	 *   weight-raise async queues
-+	 *
-+	 * . if bfqq is not weight-raised, because, if bfqq is now
-+	 *   switching to weight-raised, then last_wr_start_finish
-+	 *   stores the time when weight-raising starts
-+	 *
-+	 * . if bfqq is interactive, because, regardless of whether
-+	 *   bfqq is currently weight-raised, the weight-raising
-+	 *   period must start or restart (this case is considered
-+	 *   separately because it is not detected by the above
-+	 *   conditions, if bfqq is already weight-raised)
-+	 *
-+	 * last_wr_start_finish has to be updated also if bfqq is soft
-+	 * real-time, because the weight-raising period is constantly
-+	 * restarted on idle-to-busy transitions for these queues, but
-+	 * this is already done in bfq_bfqq_handle_idle_busy_switch if
-+	 * needed.
-+	 */
-+	if (bfqd->low_latency &&
-+		(old_wr_coeff == 1 || bfqq->wr_coeff == 1 || interactive))
-+		bfqq->last_wr_start_finish = jiffies;
-+}
-+
-+static struct request *bfq_find_rq_fmerge(struct bfq_data *bfqd,
-+					  struct bio *bio,
-+					  struct request_queue *q)
-+{
-+	struct bfq_queue *bfqq = bfqd->bio_bfqq;
-+
-+	BUG_ON(!bfqd->bio_bfqq_set);
-+
-+	if (bfqq)
-+		return elv_rb_find(&bfqq->sort_list, bio_end_sector(bio));
-+
-+	return NULL;
-+}
-+
-+static sector_t get_sdist(sector_t last_pos, struct request *rq)
-+{
-+	sector_t sdist = 0;
-+
-+	if (last_pos) {
-+		if (last_pos < blk_rq_pos(rq))
-+			sdist = blk_rq_pos(rq) - last_pos;
-+		else
-+			sdist = last_pos - blk_rq_pos(rq);
-+	}
-+
-+	return sdist;
-+}
-+
-+#if 0 /* Still not clear if we can do without next two functions */
-+static void bfq_activate_request(struct request_queue *q, struct request *rq)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	bfqd->rq_in_driver++;
-+}
-+
-+static void bfq_deactivate_request(struct request_queue *q, struct request *rq)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+
-+	BUG_ON(bfqd->rq_in_driver == 0);
-+	bfqd->rq_in_driver--;
-+}
-+#endif
-+
-+static void bfq_remove_request(struct request_queue *q,
-+			       struct request *rq)
-+{
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq);
-+	struct bfq_data *bfqd = bfqq->bfqd;
-+	const int sync = rq_is_sync(rq);
-+
-+	BUG_ON(bfqq->entity.service > bfqq->entity.budget);
-+
-+	if (bfqq->next_rq == rq) {
-+		bfqq->next_rq = bfq_find_next_rq(bfqd, bfqq, rq);
-+		if (bfqq->next_rq && !RQ_BFQQ(bfqq->next_rq)) {
-+			pr_crit("no bfqq! for next rq %p bfqq %p\n",
-+				bfqq->next_rq, bfqq);
-+		}
-+
-+		BUG_ON(bfqq->next_rq && !RQ_BFQQ(bfqq->next_rq));
-+		if (bfqq->next_rq && RQ_BFQQ(bfqq->next_rq) != bfqq) {
-+			pr_crit(
-+			"wrong bfqq! for next rq %p, rq_bfqq %p bfqq %p\n",
-+			bfqq->next_rq, RQ_BFQQ(bfqq->next_rq), bfqq);
-+		}
-+		BUG_ON(bfqq->next_rq && RQ_BFQQ(bfqq->next_rq) != bfqq);
-+
-+		bfq_updated_next_req(bfqd, bfqq);
-+	}
-+
-+	if (rq->queuelist.prev != &rq->queuelist)
-+		list_del_init(&rq->queuelist);
-+	BUG_ON(bfqq->queued[sync] == 0);
-+	bfqq->queued[sync]--;
-+	bfqd->queued--;
-+	elv_rb_del(&bfqq->sort_list, rq);
-+
-+	elv_rqhash_del(q, rq);
-+	if (q->last_merge == rq)
-+		q->last_merge = NULL;
-+
-+	if (RB_EMPTY_ROOT(&bfqq->sort_list)) {
-+		bfqq->next_rq = NULL;
-+
-+		BUG_ON(bfqq->entity.budget < 0);
-+
-+		if (bfq_bfqq_busy(bfqq) && bfqq != bfqd->in_service_queue) {
-+			BUG_ON(bfqq->ref < 2); /* referred by rq and on tree */
-+			bfq_del_bfqq_busy(bfqd, bfqq, false);
-+			/*
-+			 * bfqq emptied. In normal operation, when
-+			 * bfqq is empty, bfqq->entity.service and
-+			 * bfqq->entity.budget must contain,
-+			 * respectively, the service received and the
-+			 * budget used last time bfqq emptied. These
-+			 * facts do not hold in this case, as at least
-+			 * this last removal occurred while bfqq is
-+			 * not in service. To avoid inconsistencies,
-+			 * reset both bfqq->entity.service and
-+			 * bfqq->entity.budget, if bfqq has still a
-+			 * process that may issue I/O requests to it.
-+			 */
-+			bfqq->entity.budget = bfqq->entity.service = 0;
-+		}
-+
-+		/*
-+		 * Remove queue from request-position tree as it is empty.
-+		 */
-+		if (bfqq->pos_root) {
-+			rb_erase(&bfqq->pos_node, bfqq->pos_root);
-+			bfqq->pos_root = NULL;
-+		}
-+	} else {
-+		BUG_ON(!bfqq->next_rq);
-+		bfq_pos_tree_add_move(bfqd, bfqq);
-+	}
-+
-+	if (rq->cmd_flags & REQ_META) {
-+		BUG_ON(bfqq->meta_pending == 0);
-+		bfqq->meta_pending--;
-+	}
-+}
-+
-+static bool bfq_bio_merge(struct blk_mq_hw_ctx *hctx, struct bio *bio)
-+{
-+	struct request_queue *q = hctx->queue;
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	struct request *free = NULL;
-+	/*
-+	 * bfq_bic_lookup grabs the queue_lock: invoke it now and
-+	 * store its return value for later use, to avoid nesting
-+	 * queue_lock inside the bfqd->lock. We assume that the bic
-+	 * returned by bfq_bic_lookup does not go away before
-+	 * bfqd->lock is taken.
-+	 */
-+	struct bfq_io_cq *bic = bfq_bic_lookup(bfqd, current->io_context, q);
-+	bool ret;
-+
-+	spin_lock_irq(&bfqd->lock);
-+
-+	if (bic)
-+		bfqd->bio_bfqq = bic_to_bfqq(bic, op_is_sync(bio->bi_opf));
-+	else
-+		bfqd->bio_bfqq = NULL;
-+	bfqd->bio_bic = bic;
-+	/* Set next flag just for testing purposes */
-+	bfqd->bio_bfqq_set = true;
-+
-+	ret = blk_mq_sched_try_merge(q, bio, &free);
-+
-+	/*
-+	 * XXX Not yet freeing without lock held, to avoid an
-+	 * inconsistency with respect to the lock-protected invocation
-+	 * of blk_mq_sched_try_insert_merge in bfq_bio_merge. Waiting
-+	 * for clarifications from Jens.
-+	 */
-+	if (free)
-+		blk_mq_free_request(free);
-+	bfqd->bio_bfqq_set = false;
-+	spin_unlock_irq(&bfqd->lock);
-+
-+	return ret;
-+}
-+
-+static int bfq_request_merge(struct request_queue *q, struct request **req,
-+			     struct bio *bio)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	struct request *__rq;
-+
-+	__rq = bfq_find_rq_fmerge(bfqd, bio, q);
-+	if (__rq && elv_bio_merge_ok(__rq, bio)) {
-+		*req = __rq;
-+		bfq_log(bfqd, "req %p", __rq);
-+
-+		return ELEVATOR_FRONT_MERGE;
-+	}
-+
-+	return ELEVATOR_NO_MERGE;
-+}
-+
-+static struct bfq_queue *bfq_init_rq(struct request *rq);
-+
-+static void bfq_request_merged(struct request_queue *q, struct request *req,
-+			       enum elv_merge type)
-+{
-+	BUG_ON(req->rq_flags & RQF_DISP_LIST);
-+
-+	if (type == ELEVATOR_FRONT_MERGE &&
-+	    rb_prev(&req->rb_node) &&
-+	    blk_rq_pos(req) <
-+	    blk_rq_pos(container_of(rb_prev(&req->rb_node),
-+				    struct request, rb_node))) {
-+		struct bfq_queue *bfqq = bfq_init_rq(req);
-+		struct bfq_data *bfqd = bfqq->bfqd;
-+		struct request *prev, *next_rq;
-+
-+		/* Reposition request in its sort_list */
-+		elv_rb_del(&bfqq->sort_list, req);
-+		BUG_ON(!RQ_BFQQ(req));
-+		BUG_ON(RQ_BFQQ(req) != bfqq);
-+		elv_rb_add(&bfqq->sort_list, req);
-+
-+		/* Choose next request to be served for bfqq */
-+		prev = bfqq->next_rq;
-+		next_rq = bfq_choose_req(bfqd, bfqq->next_rq, req,
-+					 bfqd->last_position);
-+		BUG_ON(!next_rq);
-+
-+		bfqq->next_rq = next_rq;
-+
-+		bfq_log_bfqq(bfqd, bfqq,
-+			"req %p prev %p next_rq %p bfqq %p",
-+			     req, prev, next_rq, bfqq);
-+
-+		/*
-+		 * If next_rq changes, update both the queue's budget to
-+		 * fit the new request and the queue's position in its
-+		 * rq_pos_tree.
-+		 */
-+		if (prev != bfqq->next_rq) {
-+			bfq_updated_next_req(bfqd, bfqq);
-+			bfq_pos_tree_add_move(bfqd, bfqq);
-+		}
-+	}
-+}
-+
-+/*
-+ * This function is called to notify the scheduler that the requests
-+ * rq and 'next' have been merged, with 'next' going away.  BFQ
-+ * exploits this hook to address the following issue: if 'next' has a
-+ * fifo_time lower that rq, then the fifo_time of rq must be set to
-+ * the value of 'next', to not forget the greater age of 'next'.
-+ *
-+ * NOTE: in this function we assume that rq is in a bfq_queue, basing
-+ * on that rq is picked from the hash table q->elevator->hash, which,
-+ * in its turn, is filled only with I/O requests present in
-+ * bfq_queues, while BFQ is in use for the request queue q. In fact,
-+ * the function that fills this hash table (elv_rqhash_add) is called
-+ * only by bfq_insert_request.
-+ */
-+static void bfq_requests_merged(struct request_queue *q, struct request *rq,
-+				struct request *next)
-+{
-+	struct bfq_queue *bfqq = bfq_init_rq(rq),
-+		*next_bfqq = bfq_init_rq(next);
-+
-+	BUG_ON(!RQ_BFQQ(rq));
-+	BUG_ON(!RQ_BFQQ(next)); /* this does not imply next is in a bfqq */
-+	BUG_ON(rq->rq_flags & RQF_DISP_LIST);
-+	BUG_ON(next->rq_flags & RQF_DISP_LIST);
-+
-+	lockdep_assert_held(&bfqq->bfqd->lock);
-+
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		     "rq %p next %p bfqq %p next_bfqq %p",
-+		     rq, next, bfqq, next_bfqq);
-+
-+	/*
-+	 * If next and rq belong to the same bfq_queue and next is older
-+	 * than rq, then reposition rq in the fifo (by substituting next
-+	 * with rq). Otherwise, if next and rq belong to different
-+	 * bfq_queues, never reposition rq: in fact, we would have to
-+	 * reposition it with respect to next's position in its own fifo,
-+	 * which would most certainly be too expensive with respect to
-+	 * the benefits.
-+	 */
-+	if (bfqq == next_bfqq &&
-+	    !list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
-+	    next->fifo_time < rq->fifo_time) {
-+		list_del_init(&rq->queuelist);
-+		list_replace_init(&next->queuelist, &rq->queuelist);
-+		rq->fifo_time = next->fifo_time;
-+	}
-+
-+	if (bfqq->next_rq == next)
-+		bfqq->next_rq = rq;
-+
-+	bfqg_stats_update_io_merged(bfqq_group(bfqq), next->cmd_flags);
-+}
-+
-+/* Must be called with bfqq != NULL */
-+static void bfq_bfqq_end_wr(struct bfq_queue *bfqq)
-+{
-+	BUG_ON(!bfqq);
-+
-+	if (bfq_bfqq_busy(bfqq)) {
-+		bfqq->bfqd->wr_busy_queues--;
-+		BUG_ON(bfqq->bfqd->wr_busy_queues < 0);
-+	}
-+	bfqq->wr_coeff = 1;
-+	bfqq->wr_cur_max_time = 0;
-+	bfqq->last_wr_start_finish = jiffies;
-+	/*
-+	 * Trigger a weight change on the next invocation of
-+	 * __bfq_entity_update_weight_prio.
-+	 */
-+	bfqq->entity.prio_changed = 1;
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		     "wrais ending at %lu, rais_max_time %u",
-+		     bfqq->last_wr_start_finish,
-+		     jiffies_to_msecs(bfqq->wr_cur_max_time));
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "wr_busy %d",
-+		     bfqq->bfqd->wr_busy_queues);
-+}
-+
-+static void bfq_end_wr_async_queues(struct bfq_data *bfqd,
-+				    struct bfq_group *bfqg)
-+{
-+	int i, j;
-+
-+	for (i = 0; i < 2; i++)
-+		for (j = 0; j < IOPRIO_BE_NR; j++)
-+			if (bfqg->async_bfqq[i][j])
-+				bfq_bfqq_end_wr(bfqg->async_bfqq[i][j]);
-+	if (bfqg->async_idle_bfqq)
-+		bfq_bfqq_end_wr(bfqg->async_idle_bfqq);
-+}
-+
-+static void bfq_end_wr(struct bfq_data *bfqd)
-+{
-+	struct bfq_queue *bfqq;
-+
-+	spin_lock_irq(&bfqd->lock);
-+
-+	list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list)
-+		bfq_bfqq_end_wr(bfqq);
-+	list_for_each_entry(bfqq, &bfqd->idle_list, bfqq_list)
-+		bfq_bfqq_end_wr(bfqq);
-+	bfq_end_wr_async(bfqd);
-+
-+	spin_unlock_irq(&bfqd->lock);
-+}
-+
-+static sector_t bfq_io_struct_pos(void *io_struct, bool request)
-+{
-+	if (request)
-+		return blk_rq_pos(io_struct);
-+	else
-+		return ((struct bio *)io_struct)->bi_iter.bi_sector;
-+}
-+
-+static int bfq_rq_close_to_sector(void *io_struct, bool request,
-+				  sector_t sector)
-+{
-+	return abs(bfq_io_struct_pos(io_struct, request) - sector) <=
-+	       BFQQ_CLOSE_THR;
-+}
-+
-+static struct bfq_queue *bfqq_find_close(struct bfq_data *bfqd,
-+					 struct bfq_queue *bfqq,
-+					 sector_t sector)
-+{
-+	struct rb_root *root = &bfq_bfqq_to_bfqg(bfqq)->rq_pos_tree;
-+	struct rb_node *parent, *node;
-+	struct bfq_queue *__bfqq;
-+
-+	if (RB_EMPTY_ROOT(root))
-+		return NULL;
-+
-+	/*
-+	 * First, if we find a request starting at the end of the last
-+	 * request, choose it.
-+	 */
-+	__bfqq = bfq_rq_pos_tree_lookup(bfqd, root, sector, &parent, NULL);
-+	if (__bfqq)
-+		return __bfqq;
-+
-+	/*
-+	 * If the exact sector wasn't found, the parent of the NULL leaf
-+	 * will contain the closest sector (rq_pos_tree sorted by
-+	 * next_request position).
-+	 */
-+	__bfqq = rb_entry(parent, struct bfq_queue, pos_node);
-+	if (bfq_rq_close_to_sector(__bfqq->next_rq, true, sector))
-+		return __bfqq;
-+
-+	if (blk_rq_pos(__bfqq->next_rq) < sector)
-+		node = rb_next(&__bfqq->pos_node);
-+	else
-+		node = rb_prev(&__bfqq->pos_node);
-+	if (!node)
-+		return NULL;
-+
-+	__bfqq = rb_entry(node, struct bfq_queue, pos_node);
-+	if (bfq_rq_close_to_sector(__bfqq->next_rq, true, sector))
-+		return __bfqq;
-+
-+	return NULL;
-+}
-+
-+static struct bfq_queue *bfq_find_close_cooperator(struct bfq_data *bfqd,
-+						   struct bfq_queue *cur_bfqq,
-+						   sector_t sector)
-+{
-+	struct bfq_queue *bfqq;
-+
-+	/*
-+	 * We shall notice if some of the queues are cooperating,
-+	 * e.g., working closely on the same area of the device. In
-+	 * that case, we can group them together and: 1) don't waste
-+	 * time idling, and 2) serve the union of their requests in
-+	 * the best possible order for throughput.
-+	 */
-+	bfqq = bfqq_find_close(bfqd, cur_bfqq, sector);
-+	if (!bfqq || bfqq == cur_bfqq)
-+		return NULL;
-+
-+	return bfqq;
-+}
-+
-+static struct bfq_queue *
-+bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq)
-+{
-+	int process_refs, new_process_refs;
-+	struct bfq_queue *__bfqq;
-+
-+	/*
-+	 * If there are no process references on the new_bfqq, then it is
-+	 * unsafe to follow the ->new_bfqq chain as other bfqq's in the chain
-+	 * may have dropped their last reference (not just their last process
-+	 * reference).
-+	 */
-+	if (!bfqq_process_refs(new_bfqq))
-+		return NULL;
-+
-+	/* Avoid a circular list and skip interim queue merges. */
-+	while ((__bfqq = new_bfqq->new_bfqq)) {
-+		if (__bfqq == bfqq)
-+			return NULL;
-+		new_bfqq = __bfqq;
-+	}
-+
-+	process_refs = bfqq_process_refs(bfqq);
-+	new_process_refs = bfqq_process_refs(new_bfqq);
-+	/*
-+	 * If the process for the bfqq has gone away, there is no
-+	 * sense in merging the queues.
-+	 */
-+	if (process_refs == 0 || new_process_refs == 0)
-+		return NULL;
-+
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "scheduling merge with queue %d",
-+		new_bfqq->pid);
-+
-+	/*
-+	 * Merging is just a redirection: the requests of the process
-+	 * owning one of the two queues are redirected to the other queue.
-+	 * The latter queue, in its turn, is set as shared if this is the
-+	 * first time that the requests of some process are redirected to
-+	 * it.
-+	 *
-+	 * We redirect bfqq to new_bfqq and not the opposite, because
-+	 * we are in the context of the process owning bfqq, thus we
-+	 * have the io_cq of this process. So we can immediately
-+	 * configure this io_cq to redirect the requests of the
-+	 * process to new_bfqq. In contrast, the io_cq of new_bfqq is
-+	 * not available any more (new_bfqq->bic == NULL).
-+	 *
-+	 * Anyway, even in case new_bfqq coincides with the in-service
-+	 * queue, redirecting requests the in-service queue is the
-+	 * best option, as we feed the in-service queue with new
-+	 * requests close to the last request served and, by doing so,
-+	 * are likely to increase the throughput.
-+	 */
-+	bfqq->new_bfqq = new_bfqq;
-+	new_bfqq->ref += process_refs;
-+	return new_bfqq;
-+}
-+
-+static bool bfq_may_be_close_cooperator(struct bfq_queue *bfqq,
-+					struct bfq_queue *new_bfqq)
-+{
-+	if (bfq_too_late_for_merging(new_bfqq)) {
-+		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			     "too late for bfq%d to be merged",
-+				new_bfqq->pid);
-+		return false;
-+	}
-+
-+	if (bfq_class_idle(bfqq) || bfq_class_idle(new_bfqq) ||
-+	    (bfqq->ioprio_class != new_bfqq->ioprio_class))
-+		return false;
-+
-+	/*
-+	 * If either of the queues has already been detected as seeky,
-+	 * then merging it with the other queue is unlikely to lead to
-+	 * sequential I/O.
-+	 */
-+	if (BFQQ_SEEKY(bfqq) || BFQQ_SEEKY(new_bfqq))
-+		return false;
-+
-+	/*
-+	 * Interleaved I/O is known to be done by (some) applications
-+	 * only for reads, so it does not make sense to merge async
-+	 * queues.
-+	 */
-+	if (!bfq_bfqq_sync(bfqq) || !bfq_bfqq_sync(new_bfqq))
-+		return false;
-+
-+	return true;
-+}
-+
-+/*
-+ * Attempt to schedule a merge of bfqq with the currently in-service
-+ * queue or with a close queue among the scheduled queues.  Return
-+ * NULL if no merge was scheduled, a pointer to the shared bfq_queue
-+ * structure otherwise.
-+ *
-+ * The OOM queue is not allowed to participate to cooperation: in fact, since
-+ * the requests temporarily redirected to the OOM queue could be redirected
-+ * again to dedicated queues at any time, the state needed to correctly
-+ * handle merging with the OOM queue would be quite complex and expensive
-+ * to maintain. Besides, in such a critical condition as an out of memory,
-+ * the benefits of queue merging may be little relevant, or even negligible.
-+ *
-+ * WARNING: queue merging may impair fairness among non-weight raised
-+ * queues, for at least two reasons: 1) the original weight of a
-+ * merged queue may change during the merged state, 2) even being the
-+ * weight the same, a merged queue may be bloated with many more
-+ * requests than the ones produced by its originally-associated
-+ * process.
-+ */
-+static struct bfq_queue *
-+bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+		     void *io_struct, bool request)
-+{
-+	struct bfq_queue *in_service_bfqq, *new_bfqq;
-+
-+	/*
-+	 * Prevent bfqq from being merged if it has been created too
-+	 * long ago. The idea is that true cooperating processes, and
-+	 * thus their associated bfq_queues, are supposed to be
-+	 * created shortly after each other. This is the case, e.g.,
-+	 * for KVM/QEMU and dump I/O threads. Basing on this
-+	 * assumption, the following filtering greatly reduces the
-+	 * probability that two non-cooperating processes, which just
-+	 * happen to do close I/O for some short time interval, have
-+	 * their queues merged by mistake.
-+	 */
-+	if (bfq_too_late_for_merging(bfqq)) {
-+		bfq_log_bfqq(bfqd, bfqq,
-+			     "would have looked for coop, but too late");
-+		return NULL;
-+	}
-+
-+	if (bfqq->new_bfqq)
-+		return bfqq->new_bfqq;
-+
-+	if (!io_struct || unlikely(bfqq == &bfqd->oom_bfqq))
-+		return NULL;
-+
-+	/* If there is only one backlogged queue, don't search. */
-+	if (bfq_tot_busy_queues(bfqd) == 1)
-+		return NULL;
-+
-+	in_service_bfqq = bfqd->in_service_queue;
-+
-+	if (in_service_bfqq && in_service_bfqq != bfqq &&
-+	    likely(in_service_bfqq != &bfqd->oom_bfqq) &&
-+	    bfq_rq_close_to_sector(io_struct, request, bfqd->in_serv_last_pos) &&
-+	    bfqq->entity.parent == in_service_bfqq->entity.parent &&
-+	    bfq_may_be_close_cooperator(bfqq, in_service_bfqq)) {
-+		new_bfqq = bfq_setup_merge(bfqq, in_service_bfqq);
-+		if (new_bfqq)
-+			return new_bfqq;
-+	}
-+	/*
-+	 * Check whether there is a cooperator among currently scheduled
-+	 * queues. The only thing we need is that the bio/request is not
-+	 * NULL, as we need it to establish whether a cooperator exists.
-+	 */
-+	new_bfqq = bfq_find_close_cooperator(bfqd, bfqq,
-+			bfq_io_struct_pos(io_struct, request));
-+
-+	BUG_ON(new_bfqq && bfqq->entity.parent != new_bfqq->entity.parent);
-+
-+	if (new_bfqq && likely(new_bfqq != &bfqd->oom_bfqq) &&
-+	    bfq_may_be_close_cooperator(bfqq, new_bfqq))
-+		return bfq_setup_merge(bfqq, new_bfqq);
-+
-+	return NULL;
-+}
-+
-+static void bfq_bfqq_save_state(struct bfq_queue *bfqq)
-+{
-+	struct bfq_io_cq *bic = bfqq->bic;
-+
-+	/*
-+	 * If !bfqq->bic, the queue is already shared or its requests
-+	 * have already been redirected to a shared queue; both idle window
-+	 * and weight raising state have already been saved. Do nothing.
-+	 */
-+	if (!bic)
-+		return;
-+
-+	bic->saved_ttime = bfqq->ttime;
-+	bic->saved_has_short_ttime = bfq_bfqq_has_short_ttime(bfqq);
-+	bic->saved_IO_bound = bfq_bfqq_IO_bound(bfqq);
-+	bic->saved_in_large_burst = bfq_bfqq_in_large_burst(bfqq);
-+	bic->was_in_burst_list = !hlist_unhashed(&bfqq->burst_list_node);
-+	if (unlikely(bfq_bfqq_just_created(bfqq) &&
-+		     !bfq_bfqq_in_large_burst(bfqq) &&
-+		     bfqq->bfqd->low_latency)) {
-+		/*
-+		 * bfqq being merged ritgh after being created: bfqq
-+		 * would have deserved interactive weight raising, but
-+		 * did not make it to be set in a weight-raised state,
-+		 * because of this early merge.  Store directly the
-+		 * weight-raising state that would have been assigned
-+		 * to bfqq, so that to avoid that bfqq unjustly fails
-+		 * to enjoy weight raising if split soon.
-+		 */
-+		bic->saved_wr_coeff = bfqq->bfqd->bfq_wr_coeff;
-+		bic->saved_wr_cur_max_time = bfq_wr_duration(bfqq->bfqd);
-+		bic->saved_last_wr_start_finish = jiffies;
-+	} else {
-+		bic->saved_wr_coeff = bfqq->wr_coeff;
-+		bic->saved_wr_start_at_switch_to_srt =
-+			bfqq->wr_start_at_switch_to_srt;
-+		bic->saved_last_wr_start_finish = bfqq->last_wr_start_finish;
-+		bic->saved_wr_cur_max_time = bfqq->wr_cur_max_time;
-+	}
-+	BUG_ON(time_is_after_jiffies(bfqq->last_wr_start_finish));
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		     "bic %p wr_coeff %d start_finish %lu max_time %lu",
-+		     bic, bfqq->wr_coeff, bfqq->last_wr_start_finish,
-+		     bfqq->wr_cur_max_time);
-+}
-+
-+static void
-+bfq_merge_bfqqs(struct bfq_data *bfqd, struct bfq_io_cq *bic,
-+		struct bfq_queue *bfqq, struct bfq_queue *new_bfqq)
-+{
-+	bfq_log_bfqq(bfqd, bfqq, "merging with queue %lu",
-+		     (unsigned long) new_bfqq->pid);
-+	BUG_ON(bfqq->bic && bfqq->bic == new_bfqq->bic);
-+	/* Save weight raising and idle window of the merged queues */
-+	bfq_bfqq_save_state(bfqq);
-+	bfq_bfqq_save_state(new_bfqq);
-+
-+	if (bfq_bfqq_IO_bound(bfqq))
-+		bfq_mark_bfqq_IO_bound(new_bfqq);
-+	bfq_clear_bfqq_IO_bound(bfqq);
-+
-+	/*
-+	 * If bfqq is weight-raised, then let new_bfqq inherit
-+	 * weight-raising. To reduce false positives, neglect the case
-+	 * where bfqq has just been created, but has not yet made it
-+	 * to be weight-raised (which may happen because EQM may merge
-+	 * bfqq even before bfq_add_request is executed for the first
-+	 * time for bfqq). Handling this case would however be very
-+	 * easy, thanks to the flag just_created.
-+	 */
-+	if (new_bfqq->wr_coeff == 1 && bfqq->wr_coeff > 1) {
-+		new_bfqq->wr_coeff = bfqq->wr_coeff;
-+		new_bfqq->wr_cur_max_time = bfqq->wr_cur_max_time;
-+		new_bfqq->last_wr_start_finish = bfqq->last_wr_start_finish;
-+		new_bfqq->wr_start_at_switch_to_srt =
-+			bfqq->wr_start_at_switch_to_srt;
-+		if (bfq_bfqq_busy(new_bfqq)) {
-+			bfqd->wr_busy_queues++;
-+			BUG_ON(bfqd->wr_busy_queues >
-+			       bfq_tot_busy_queues(bfqd));
-+		}
-+
-+		new_bfqq->entity.prio_changed = 1;
-+		bfq_log_bfqq(bfqd, new_bfqq,
-+			     "wr start after merge with %d, rais_max_time %u",
-+			     bfqq->pid,
-+			     jiffies_to_msecs(bfqq->wr_cur_max_time));
-+	}
-+
-+	if (bfqq->wr_coeff > 1) { /* bfqq has given its wr to new_bfqq */
-+		bfqq->wr_coeff = 1;
-+		bfqq->entity.prio_changed = 1;
-+		if (bfq_bfqq_busy(bfqq)) {
-+			bfqd->wr_busy_queues--;
-+			BUG_ON(bfqd->wr_busy_queues < 0);
-+		}
-+
-+	}
-+
-+	bfq_log_bfqq(bfqd, new_bfqq, "wr_busy %d",
-+		     bfqd->wr_busy_queues);
-+
-+	/*
-+	 * Merge queues (that is, let bic redirect its requests to new_bfqq)
-+	 */
-+	bic_set_bfqq(bic, new_bfqq, 1);
-+	bfq_mark_bfqq_coop(new_bfqq);
-+	/*
-+	 * new_bfqq now belongs to at least two bics (it is a shared queue):
-+	 * set new_bfqq->bic to NULL. bfqq either:
-+	 * - does not belong to any bic any more, and hence bfqq->bic must
-+	 *   be set to NULL, or
-+	 * - is a queue whose owning bics have already been redirected to a
-+	 *   different queue, hence the queue is destined to not belong to
-+	 *   any bic soon and bfqq->bic is already NULL (therefore the next
-+	 *   assignment causes no harm).
-+	 */
-+	new_bfqq->bic = NULL;
-+	bfqq->bic = NULL;
-+	/* release process reference to bfqq */
-+	bfq_put_queue(bfqq);
-+}
-+
-+static bool bfq_allow_bio_merge(struct request_queue *q, struct request *rq,
-+				struct bio *bio)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	bool is_sync = op_is_sync(bio->bi_opf);
-+	struct bfq_queue *bfqq = bfqd->bio_bfqq, *new_bfqq;
-+
-+	assert_spin_locked(&bfqd->lock);
-+	/*
-+	 * Disallow merge of a sync bio into an async request.
-+	 */
-+	if (is_sync && !rq_is_sync(rq))
-+		return false;
-+
-+	/*
-+	 * Lookup the bfqq that this bio will be queued with. Allow
-+	 * merge only if rq is queued there.
-+	 */
-+	BUG_ON(!bfqd->bio_bfqq_set);
-+	if (!bfqq)
-+		return false;
-+
-+	/*
-+	 * We take advantage of this function to perform an early merge
-+	 * of the queues of possible cooperating processes.
-+	 */
-+	new_bfqq = bfq_setup_cooperator(bfqd, bfqq, bio, false);
-+	BUG_ON(new_bfqq == bfqq);
-+	if (new_bfqq) {
-+		/*
-+		 * bic still points to bfqq, then it has not yet been
-+		 * redirected to some other bfq_queue, and a queue
-+		 * merge beween bfqq and new_bfqq can be safely
-+		 * fulfillled, i.e., bic can be redirected to new_bfqq
-+		 * and bfqq can be put.
-+		 */
-+		bfq_merge_bfqqs(bfqd, bfqd->bio_bic, bfqq,
-+				new_bfqq);
-+		/*
-+		 * If we get here, bio will be queued into new_queue,
-+		 * so use new_bfqq to decide whether bio and rq can be
-+		 * merged.
-+		 */
-+		bfqq = new_bfqq;
-+
-+		/*
-+		 * Change also bqfd->bio_bfqq, as
-+		 * bfqd->bio_bic now points to new_bfqq, and
-+		 * this function may be invoked again (and then may
-+		 * use again bqfd->bio_bfqq).
-+		 */
-+		bfqd->bio_bfqq = bfqq;
-+	}
-+	return bfqq == RQ_BFQQ(rq);
-+}
-+
-+/*
-+ * Set the maximum time for the in-service queue to consume its
-+ * budget. This prevents seeky processes from lowering the throughput.
-+ * In practice, a time-slice service scheme is used with seeky
-+ * processes.
-+ */
-+static void bfq_set_budget_timeout(struct bfq_data *bfqd,
-+				   struct bfq_queue *bfqq)
-+{
-+	unsigned int timeout_coeff;
-+
-+	if (bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time)
-+		timeout_coeff = 1;
-+	else
-+		timeout_coeff = bfqq->entity.weight / bfqq->entity.orig_weight;
-+
-+	bfqd->last_budget_start = ktime_get();
-+
-+	bfqq->budget_timeout = jiffies +
-+		bfqd->bfq_timeout * timeout_coeff;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "%u",
-+		jiffies_to_msecs(bfqd->bfq_timeout * timeout_coeff));
-+}
-+
-+static void __bfq_set_in_service_queue(struct bfq_data *bfqd,
-+				       struct bfq_queue *bfqq)
-+{
-+	if (bfqq) {
-+		bfq_clear_bfqq_fifo_expire(bfqq);
-+
-+		bfqd->budgets_assigned = (bfqd->budgets_assigned*7 + 256) / 8;
-+
-+		BUG_ON(bfqq == bfqd->in_service_queue);
-+		BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list));
-+
-+		if (time_is_before_jiffies(bfqq->last_wr_start_finish) &&
-+		    bfqq->wr_coeff > 1 &&
-+		    bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time &&
-+		    time_is_before_jiffies(bfqq->budget_timeout)) {
-+			/*
-+			 * For soft real-time queues, move the start
-+			 * of the weight-raising period forward by the
-+			 * time the queue has not received any
-+			 * service. Otherwise, a relatively long
-+			 * service delay is likely to cause the
-+			 * weight-raising period of the queue to end,
-+			 * because of the short duration of the
-+			 * weight-raising period of a soft real-time
-+			 * queue.  It is worth noting that this move
-+			 * is not so dangerous for the other queues,
-+			 * because soft real-time queues are not
-+			 * greedy.
-+			 *
-+			 * To not add a further variable, we use the
-+			 * overloaded field budget_timeout to
-+			 * determine for how long the queue has not
-+			 * received service, i.e., how much time has
-+			 * elapsed since the queue expired. However,
-+			 * this is a little imprecise, because
-+			 * budget_timeout is set to jiffies if bfqq
-+			 * not only expires, but also remains with no
-+			 * request.
-+			 */
-+			if (time_after(bfqq->budget_timeout,
-+				       bfqq->last_wr_start_finish))
-+				bfqq->last_wr_start_finish +=
-+					jiffies - bfqq->budget_timeout;
-+			else
-+				bfqq->last_wr_start_finish = jiffies;
-+
-+			if (time_is_after_jiffies(bfqq->last_wr_start_finish)) {
-+			       pr_crit(
-+			       "BFQ WARNING:last %lu budget %lu jiffies %lu",
-+			       bfqq->last_wr_start_finish,
-+			       bfqq->budget_timeout,
-+			       jiffies);
-+			       pr_crit("diff %lu", jiffies -
-+				       max_t(unsigned long,
-+					     bfqq->last_wr_start_finish,
-+					     bfqq->budget_timeout));
-+			       bfqq->last_wr_start_finish = jiffies;
-+			}
-+		}
-+
-+		bfq_set_budget_timeout(bfqd, bfqq);
-+		bfq_log_bfqq(bfqd, bfqq,
-+			     "cur-budget = %d prio_class %d",
-+			     bfqq->entity.budget, bfqq->ioprio_class);
-+	} else
-+		bfq_log(bfqd, "NULL");
-+
-+	bfqd->in_service_queue = bfqq;
-+}
-+
-+/*
-+ * Get and set a new queue for service.
-+ */
-+static struct bfq_queue *bfq_set_in_service_queue(struct bfq_data *bfqd)
-+{
-+	struct bfq_queue *bfqq = bfq_get_next_queue(bfqd);
-+
-+	__bfq_set_in_service_queue(bfqd, bfqq);
-+	return bfqq;
-+}
-+
-+static void bfq_arm_slice_timer(struct bfq_data *bfqd)
-+{
-+	struct bfq_queue *bfqq = bfqd->in_service_queue;
-+	u32 sl;
-+
-+	BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list));
-+
-+	bfq_mark_bfqq_wait_request(bfqq);
-+
-+	/*
-+	 * We don't want to idle for seeks, but we do want to allow
-+	 * fair distribution of slice time for a process doing back-to-back
-+	 * seeks. So allow a little bit of time for him to submit a new rq.
-+	 *
-+	 * To prevent processes with (partly) seeky workloads from
-+	 * being too ill-treated, grant them a small fraction of the
-+	 * assigned budget before reducing the waiting time to
-+	 * BFQ_MIN_TT. This happened to help reduce latency.
-+	 */
-+	sl = bfqd->bfq_slice_idle;
-+	/*
-+	 * Unless the queue is being weight-raised or the scenario is
-+	 * asymmetric, grant only minimum idle time if the queue
-+	 * is seeky. A long idling is preserved for a weight-raised
-+	 * queue, or, more in general, in an asymemtric scenario,
-+	 * because a long idling is needed for guaranteeing to a queue
-+	 * its reserved share of the throughput (in particular, it is
-+	 * needed if the queue has a higher weight than some other
-+	 * queue).
-+	 */
-+	if (BFQQ_SEEKY(bfqq) && bfqq->wr_coeff == 1 &&
-+	    bfq_symmetric_scenario(bfqd))
-+		sl = min_t(u32, sl, BFQ_MIN_TT);
-+
-+	bfqd->last_idling_start = ktime_get();
-+	hrtimer_start(&bfqd->idle_slice_timer, ns_to_ktime(sl),
-+		      HRTIMER_MODE_REL);
-+	bfqg_stats_set_start_idle_time(bfqq_group(bfqq));
-+	bfq_log(bfqd, "arm idle: %ld/%ld ms",
-+		sl / NSEC_PER_MSEC, bfqd->bfq_slice_idle / NSEC_PER_MSEC);
-+}
-+
-+/*
-+ * In autotuning mode, max_budget is dynamically recomputed as the
-+ * amount of sectors transferred in timeout at the estimated peak
-+ * rate. This enables BFQ to utilize a full timeslice with a full
-+ * budget, even if the in-service queue is served at peak rate. And
-+ * this maximises throughput with sequential workloads.
-+ */
-+static unsigned long bfq_calc_max_budget(struct bfq_data *bfqd)
-+{
-+	return (u64)bfqd->peak_rate * USEC_PER_MSEC *
-+		jiffies_to_msecs(bfqd->bfq_timeout)>>BFQ_RATE_SHIFT;
-+}
-+
-+/*
-+ * Update parameters related to throughput and responsiveness, as a
-+ * function of the estimated peak rate. See comments on
-+ * bfq_calc_max_budget(), and on the ref_wr_duration array.
-+ */
-+static void update_thr_responsiveness_params(struct bfq_data *bfqd)
-+{
-+	if (bfqd->bfq_user_max_budget == 0) {
-+		bfqd->bfq_max_budget =
-+			bfq_calc_max_budget(bfqd);
-+		BUG_ON(bfqd->bfq_max_budget < 0);
-+		bfq_log(bfqd, "new max_budget = %d",
-+			bfqd->bfq_max_budget);
-+	}
-+}
-+
-+static void bfq_reset_rate_computation(struct bfq_data *bfqd, struct request *rq)
-+{
-+	if (rq != NULL) { /* new rq dispatch now, reset accordingly */
-+		bfqd->last_dispatch = bfqd->first_dispatch = ktime_get_ns() ;
-+		bfqd->peak_rate_samples = 1;
-+		bfqd->sequential_samples = 0;
-+		bfqd->tot_sectors_dispatched = bfqd->last_rq_max_size =
-+			blk_rq_sectors(rq);
-+	} else /* no new rq dispatched, just reset the number of samples */
-+		bfqd->peak_rate_samples = 0; /* full re-init on next disp. */
-+
-+	bfq_log(bfqd,
-+		"at end, sample %u/%u tot_sects %llu",
-+		bfqd->peak_rate_samples, bfqd->sequential_samples,
-+		bfqd->tot_sectors_dispatched);
-+}
-+
-+static void bfq_update_rate_reset(struct bfq_data *bfqd, struct request *rq)
-+{
-+	u32 rate, weight, divisor;
-+
-+	/*
-+	 * For the convergence property to hold (see comments on
-+	 * bfq_update_peak_rate()) and for the assessment to be
-+	 * reliable, a minimum number of samples must be present, and
-+	 * a minimum amount of time must have elapsed. If not so, do
-+	 * not compute new rate. Just reset parameters, to get ready
-+	 * for a new evaluation attempt.
-+	 */
-+	if (bfqd->peak_rate_samples < BFQ_RATE_MIN_SAMPLES ||
-+	    bfqd->delta_from_first < BFQ_RATE_MIN_INTERVAL) {
-+		bfq_log(bfqd,
-+	"only resetting, delta_first %lluus samples %d",
-+			bfqd->delta_from_first>>10, bfqd->peak_rate_samples);
-+		goto reset_computation;
-+	}
-+
-+	/*
-+	 * If a new request completion has occurred after last
-+	 * dispatch, then, to approximate the rate at which requests
-+	 * have been served by the device, it is more precise to
-+	 * extend the observation interval to the last completion.
-+	 */
-+	bfqd->delta_from_first =
-+		max_t(u64, bfqd->delta_from_first,
-+		      bfqd->last_completion - bfqd->first_dispatch);
-+
-+	BUG_ON(bfqd->delta_from_first == 0);
-+	/*
-+	 * Rate computed in sects/usec, and not sects/nsec, for
-+	 * precision issues.
-+	 */
-+	rate = div64_ul(bfqd->tot_sectors_dispatched<<BFQ_RATE_SHIFT,
-+			div_u64(bfqd->delta_from_first, NSEC_PER_USEC));
-+
-+	bfq_log(bfqd,
-+"tot_sects %llu delta_first %lluus rate %llu sects/s (%d)",
-+		bfqd->tot_sectors_dispatched, bfqd->delta_from_first>>10,
-+		((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT),
-+		rate > 20<<BFQ_RATE_SHIFT);
-+
-+	/*
-+	 * Peak rate not updated if:
-+	 * - the percentage of sequential dispatches is below 3/4 of the
-+	 *   total, and rate is below the current estimated peak rate
-+	 * - rate is unreasonably high (> 20M sectors/sec)
-+	 */
-+	if ((bfqd->sequential_samples < (3 * bfqd->peak_rate_samples)>>2 &&
-+	     rate <= bfqd->peak_rate) ||
-+		rate > 20<<BFQ_RATE_SHIFT) {
-+		bfq_log(bfqd,
-+		"goto reset, samples %u/%u rate/peak %llu/%llu",
-+		bfqd->peak_rate_samples, bfqd->sequential_samples,
-+		((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT),
-+		((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT));
-+		goto reset_computation;
-+	} else {
-+		bfq_log(bfqd,
-+		"do update, samples %u/%u rate/peak %llu/%llu",
-+		bfqd->peak_rate_samples, bfqd->sequential_samples,
-+		((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT),
-+		((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT));
-+	}
-+
-+	/*
-+	 * We have to update the peak rate, at last! To this purpose,
-+	 * we use a low-pass filter. We compute the smoothing constant
-+	 * of the filter as a function of the 'weight' of the new
-+	 * measured rate.
-+	 *
-+	 * As can be seen in next formulas, we define this weight as a
-+	 * quantity proportional to how sequential the workload is,
-+	 * and to how long the observation time interval is.
-+	 *
-+	 * The weight runs from 0 to 8. The maximum value of the
-+	 * weight, 8, yields the minimum value for the smoothing
-+	 * constant. At this minimum value for the smoothing constant,
-+	 * the measured rate contributes for half of the next value of
-+	 * the estimated peak rate.
-+	 *
-+	 * So, the first step is to compute the weight as a function
-+	 * of how sequential the workload is. Note that the weight
-+	 * cannot reach 9, because bfqd->sequential_samples cannot
-+	 * become equal to bfqd->peak_rate_samples, which, in its
-+	 * turn, holds true because bfqd->sequential_samples is not
-+	 * incremented for the first sample.
-+	 */
-+	weight = (9 * bfqd->sequential_samples) / bfqd->peak_rate_samples;
-+
-+	/*
-+	 * Second step: further refine the weight as a function of the
-+	 * duration of the observation interval.
-+	 */
-+	weight = min_t(u32, 8,
-+		       div_u64(weight * bfqd->delta_from_first,
-+			       BFQ_RATE_REF_INTERVAL));
-+
-+	/*
-+	 * Divisor ranging from 10, for minimum weight, to 2, for
-+	 * maximum weight.
-+	 */
-+	divisor = 10 - weight;
-+	BUG_ON(divisor == 0);
-+
-+	/*
-+	 * Finally, update peak rate:
-+	 *
-+	 * peak_rate = peak_rate * (divisor-1) / divisor  +  rate / divisor
-+	 */
-+	bfqd->peak_rate *= divisor-1;
-+	bfqd->peak_rate /= divisor;
-+	rate /= divisor; /* smoothing constant alpha = 1/divisor */
-+
-+	bfq_log(bfqd,
-+		"divisor %d tmp_peak_rate %llu tmp_rate %u",
-+		divisor,
-+		((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT),
-+		(u32)((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT));
-+
-+	BUG_ON(bfqd->peak_rate == 0);
-+	BUG_ON(bfqd->peak_rate > 20<<BFQ_RATE_SHIFT);
-+
-+	bfqd->peak_rate += rate;
-+
-+	/*
-+	 * For a very slow device, bfqd->peak_rate can reach 0 (see
-+	 * the minimum representable values reported in the comments
-+	 * on BFQ_RATE_SHIFT). Push to 1 if this happens, to avoid
-+	 * divisions by zero where bfqd->peak_rate is used as a
-+	 * divisor.
-+	 */
-+	bfqd->peak_rate = max_t(u32, 1, bfqd->peak_rate);
-+
-+	update_thr_responsiveness_params(bfqd);
-+	BUG_ON(bfqd->peak_rate > 20<<BFQ_RATE_SHIFT);
-+
-+reset_computation:
-+	bfq_reset_rate_computation(bfqd, rq);
-+}
-+
-+/*
-+ * Update the read/write peak rate (the main quantity used for
-+ * auto-tuning, see update_thr_responsiveness_params()).
-+ *
-+ * It is not trivial to estimate the peak rate (correctly): because of
-+ * the presence of sw and hw queues between the scheduler and the
-+ * device components that finally serve I/O requests, it is hard to
-+ * say exactly when a given dispatched request is served inside the
-+ * device, and for how long. As a consequence, it is hard to know
-+ * precisely at what rate a given set of requests is actually served
-+ * by the device.
-+ *
-+ * On the opposite end, the dispatch time of any request is trivially
-+ * available, and, from this piece of information, the "dispatch rate"
-+ * of requests can be immediately computed. So, the idea in the next
-+ * function is to use what is known, namely request dispatch times
-+ * (plus, when useful, request completion times), to estimate what is
-+ * unknown, namely in-device request service rate.
-+ *
-+ * The main issue is that, because of the above facts, the rate at
-+ * which a certain set of requests is dispatched over a certain time
-+ * interval can vary greatly with respect to the rate at which the
-+ * same requests are then served. But, since the size of any
-+ * intermediate queue is limited, and the service scheme is lossless
-+ * (no request is silently dropped), the following obvious convergence
-+ * property holds: the number of requests dispatched MUST become
-+ * closer and closer to the number of requests completed as the
-+ * observation interval grows. This is the key property used in
-+ * the next function to estimate the peak service rate as a function
-+ * of the observed dispatch rate. The function assumes to be invoked
-+ * on every request dispatch.
-+ */
-+static void bfq_update_peak_rate(struct bfq_data *bfqd, struct request *rq)
-+{
-+	u64 now_ns = ktime_get_ns();
-+
-+	if (bfqd->peak_rate_samples == 0) { /* first dispatch */
-+		bfq_log(bfqd,
-+		"goto reset, samples %d",
-+				bfqd->peak_rate_samples) ;
-+		bfq_reset_rate_computation(bfqd, rq);
-+		goto update_last_values; /* will add one sample */
-+	}
-+
-+	/*
-+	 * Device idle for very long: the observation interval lasting
-+	 * up to this dispatch cannot be a valid observation interval
-+	 * for computing a new peak rate (similarly to the late-
-+	 * completion event in bfq_completed_request()). Go to
-+	 * update_rate_and_reset to have the following three steps
-+	 * taken:
-+	 * - close the observation interval at the last (previous)
-+	 *   request dispatch or completion
-+	 * - compute rate, if possible, for that observation interval
-+	 * - start a new observation interval with this dispatch
-+	 */
-+	if (now_ns - bfqd->last_dispatch > 100*NSEC_PER_MSEC &&
-+	    bfqd->rq_in_driver == 0) {
-+		bfq_log(bfqd,
-+"jumping to updating&resetting delta_last %lluus samples %d",
-+			(now_ns - bfqd->last_dispatch)>>10,
-+			bfqd->peak_rate_samples) ;
-+		goto update_rate_and_reset;
-+	}
-+
-+	/* Update sampling information */
-+	bfqd->peak_rate_samples++;
-+
-+	if ((bfqd->rq_in_driver > 0 ||
-+		now_ns - bfqd->last_completion < BFQ_MIN_TT)
-+	    && !BFQ_RQ_SEEKY(bfqd, bfqd->last_position, rq))
-+		bfqd->sequential_samples++;
-+
-+	bfqd->tot_sectors_dispatched += blk_rq_sectors(rq);
-+
-+	/* Reset max observed rq size every 32 dispatches */
-+	if (likely(bfqd->peak_rate_samples % 32))
-+		bfqd->last_rq_max_size =
-+			max_t(u32, blk_rq_sectors(rq), bfqd->last_rq_max_size);
-+	else
-+		bfqd->last_rq_max_size = blk_rq_sectors(rq);
-+
-+	bfqd->delta_from_first = now_ns - bfqd->first_dispatch;
-+
-+	bfq_log(bfqd,
-+	"added samples %u/%u tot_sects %llu delta_first %lluus",
-+		bfqd->peak_rate_samples, bfqd->sequential_samples,
-+		bfqd->tot_sectors_dispatched,
-+		bfqd->delta_from_first>>10);
-+
-+	/* Target observation interval not yet reached, go on sampling */
-+	if (bfqd->delta_from_first < BFQ_RATE_REF_INTERVAL)
-+		goto update_last_values;
-+
-+update_rate_and_reset:
-+	bfq_update_rate_reset(bfqd, rq);
-+update_last_values:
-+	bfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
-+	if (RQ_BFQQ(rq) == bfqd->in_service_queue)
-+		bfqd->in_serv_last_pos = bfqd->last_position;
-+	bfqd->last_dispatch = now_ns;
-+
-+	bfq_log(bfqd,
-+	"delta_first %lluus last_pos %llu peak_rate %llu",
-+		(now_ns - bfqd->first_dispatch)>>10,
-+		(unsigned long long) bfqd->last_position,
-+		((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT));
-+	bfq_log(bfqd,
-+	"samples at end %d", bfqd->peak_rate_samples);
-+}
-+
-+/*
-+ * Remove request from internal lists.
-+ */
-+static void bfq_dispatch_remove(struct request_queue *q, struct request *rq)
-+{
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq);
-+
-+	/*
-+	 * For consistency, the next instruction should have been
-+	 * executed after removing the request from the queue and
-+	 * dispatching it.  We execute instead this instruction before
-+	 * bfq_remove_request() (and hence introduce a temporary
-+	 * inconsistency), for efficiency.  In fact, should this
-+	 * dispatch occur for a non in-service bfqq, this anticipated
-+	 * increment prevents two counters related to bfqq->dispatched
-+	 * from risking to be, first, uselessly decremented, and then
-+	 * incremented again when the (new) value of bfqq->dispatched
-+	 * happens to be taken into account.
-+	 */
-+	bfqq->dispatched++;
-+	bfq_update_peak_rate(q->elevator->elevator_data, rq);
-+
-+	bfq_remove_request(q, rq);
-+}
-+
-+static void __bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	BUG_ON(bfqq != bfqd->in_service_queue);
-+
-+	/*
-+	 * If this bfqq is shared between multiple processes, check
-+	 * to make sure that those processes are still issuing I/Os
-+	 * within the mean seek distance. If not, it may be time to
-+	 * break the queues apart again.
-+	 */
-+	if (bfq_bfqq_coop(bfqq) && BFQQ_SEEKY(bfqq))
-+		bfq_mark_bfqq_split_coop(bfqq);
-+
-+	if (RB_EMPTY_ROOT(&bfqq->sort_list)) {
-+		if (bfqq->dispatched == 0)
-+			/*
-+			 * Overloading budget_timeout field to store
-+			 * the time at which the queue remains with no
-+			 * backlog and no outstanding request; used by
-+			 * the weight-raising mechanism.
-+			 */
-+			bfqq->budget_timeout = jiffies;
-+
-+		bfq_del_bfqq_busy(bfqd, bfqq, true);
-+	} else {
-+		bfq_requeue_bfqq(bfqd, bfqq, true);
-+		/*
-+		 * Resort priority tree of potential close cooperators.
-+		 */
-+		bfq_pos_tree_add_move(bfqd, bfqq);
-+	}
-+
-+	/*
-+	 * All in-service entities must have been properly deactivated
-+	 * or requeued before executing the next function, which
-+	 * resets all in-service entites as no more in service.
-+	 */
-+	__bfq_bfqd_reset_in_service(bfqd);
-+}
-+
-+/**
-+ * __bfq_bfqq_recalc_budget - try to adapt the budget to the @bfqq behavior.
-+ * @bfqd: device data.
-+ * @bfqq: queue to update.
-+ * @reason: reason for expiration.
-+ *
-+ * Handle the feedback on @bfqq budget at queue expiration.
-+ * See the body for detailed comments.
-+ */
-+static void __bfq_bfqq_recalc_budget(struct bfq_data *bfqd,
-+				     struct bfq_queue *bfqq,
-+				     enum bfqq_expiration reason)
-+{
-+	struct request *next_rq;
-+	int budget, min_budget;
-+
-+	BUG_ON(bfqq != bfqd->in_service_queue);
-+
-+	min_budget = bfq_min_budget(bfqd);
-+
-+	if (bfqq->wr_coeff == 1)
-+		budget = bfqq->max_budget;
-+	else /*
-+	      * Use a constant, low budget for weight-raised queues,
-+	      * to help achieve a low latency. Keep it slightly higher
-+	      * than the minimum possible budget, to cause a little
-+	      * bit fewer expirations.
-+	      */
-+		budget = 2 * min_budget;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "last budg %d, budg left %d",
-+		bfqq->entity.budget, bfq_bfqq_budget_left(bfqq));
-+	bfq_log_bfqq(bfqd, bfqq, "last max_budg %d, min budg %d",
-+		budget, bfq_min_budget(bfqd));
-+	bfq_log_bfqq(bfqd, bfqq, "sync %d, seeky %d",
-+		bfq_bfqq_sync(bfqq), BFQQ_SEEKY(bfqd->in_service_queue));
-+
-+	if (bfq_bfqq_sync(bfqq) && bfqq->wr_coeff == 1) {
-+		switch (reason) {
-+		/*
-+		 * Caveat: in all the following cases we trade latency
-+		 * for throughput.
-+		 */
-+		case BFQ_BFQQ_TOO_IDLE:
-+			/*
-+			 * This is the only case where we may reduce
-+			 * the budget: if there is no request of the
-+			 * process still waiting for completion, then
-+			 * we assume (tentatively) that the timer has
-+			 * expired because the batch of requests of
-+			 * the process could have been served with a
-+			 * smaller budget.  Hence, betting that
-+			 * process will behave in the same way when it
-+			 * becomes backlogged again, we reduce its
-+			 * next budget.  As long as we guess right,
-+			 * this budget cut reduces the latency
-+			 * experienced by the process.
-+			 *
-+			 * However, if there are still outstanding
-+			 * requests, then the process may have not yet
-+			 * issued its next request just because it is
-+			 * still waiting for the completion of some of
-+			 * the still outstanding ones.  So in this
-+			 * subcase we do not reduce its budget, on the
-+			 * contrary we increase it to possibly boost
-+			 * the throughput, as discussed in the
-+			 * comments to the BUDGET_TIMEOUT case.
-+			 */
-+			if (bfqq->dispatched > 0) /* still outstanding reqs */
-+				budget = min(budget * 2, bfqd->bfq_max_budget);
-+			else {
-+				if (budget > 5 * min_budget)
-+					budget -= 4 * min_budget;
-+				else
-+					budget = min_budget;
-+			}
-+			break;
-+		case BFQ_BFQQ_BUDGET_TIMEOUT:
-+			/*
-+			 * We double the budget here because it gives
-+			 * the chance to boost the throughput if this
-+			 * is not a seeky process (and has bumped into
-+			 * this timeout because of, e.g., ZBR).
-+			 */
-+			budget = min(budget * 2, bfqd->bfq_max_budget);
-+			break;
-+		case BFQ_BFQQ_BUDGET_EXHAUSTED:
-+			/*
-+			 * The process still has backlog, and did not
-+			 * let either the budget timeout or the disk
-+			 * idling timeout expire. Hence it is not
-+			 * seeky, has a short thinktime and may be
-+			 * happy with a higher budget too. So
-+			 * definitely increase the budget of this good
-+			 * candidate to boost the disk throughput.
-+			 */
-+			budget = min(budget * 4, bfqd->bfq_max_budget);
-+			break;
-+		case BFQ_BFQQ_NO_MORE_REQUESTS:
-+			/*
-+			 * For queues that expire for this reason, it
-+			 * is particularly important to keep the
-+			 * budget close to the actual service they
-+			 * need. Doing so reduces the timestamp
-+			 * misalignment problem described in the
-+			 * comments in the body of
-+			 * __bfq_activate_entity. In fact, suppose
-+			 * that a queue systematically expires for
-+			 * BFQ_BFQQ_NO_MORE_REQUESTS and presents a
-+			 * new request in time to enjoy timestamp
-+			 * back-shifting. The larger the budget of the
-+			 * queue is with respect to the service the
-+			 * queue actually requests in each service
-+			 * slot, the more times the queue can be
-+			 * reactivated with the same virtual finish
-+			 * time. It follows that, even if this finish
-+			 * time is pushed to the system virtual time
-+			 * to reduce the consequent timestamp
-+			 * misalignment, the queue unjustly enjoys for
-+			 * many re-activations a lower finish time
-+			 * than all newly activated queues.
-+			 *
-+			 * The service needed by bfqq is measured
-+			 * quite precisely by bfqq->entity.service.
-+			 * Since bfqq does not enjoy device idling,
-+			 * bfqq->entity.service is equal to the number
-+			 * of sectors that the process associated with
-+			 * bfqq requested to read/write before waiting
-+			 * for request completions, or blocking for
-+			 * other reasons.
-+			 */
-+			budget = max_t(int, bfqq->entity.service, min_budget);
-+			break;
-+		default:
-+			return;
-+		}
-+	} else if (!bfq_bfqq_sync(bfqq))
-+		/*
-+		 * Async queues get always the maximum possible
-+		 * budget, as for them we do not care about latency
-+		 * (in addition, their ability to dispatch is limited
-+		 * by the charging factor).
-+		 */
-+		budget = bfqd->bfq_max_budget;
-+
-+	bfqq->max_budget = budget;
-+
-+	if (bfqd->budgets_assigned >= bfq_stats_min_budgets &&
-+	    !bfqd->bfq_user_max_budget)
-+		bfqq->max_budget = min(bfqq->max_budget, bfqd->bfq_max_budget);
-+
-+	/*
-+	 * If there is still backlog, then assign a new budget, making
-+	 * sure that it is large enough for the next request.  Since
-+	 * the finish time of bfqq must be kept in sync with the
-+	 * budget, be sure to call __bfq_bfqq_expire() *after* this
-+	 * update.
-+	 *
-+	 * If there is no backlog, then no need to update the budget;
-+	 * it will be updated on the arrival of a new request.
-+	 */
-+	next_rq = bfqq->next_rq;
-+	if (next_rq) {
-+		BUG_ON(reason == BFQ_BFQQ_TOO_IDLE ||
-+		       reason == BFQ_BFQQ_NO_MORE_REQUESTS);
-+		bfqq->entity.budget = max_t(unsigned long, bfqq->max_budget,
-+					    bfq_serv_to_charge(next_rq, bfqq));
-+		BUG_ON(!bfq_bfqq_busy(bfqq));
-+		BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list));
-+	}
-+
-+	bfq_log_bfqq(bfqd, bfqq, "head sect: %u, new budget %d",
-+			next_rq ? blk_rq_sectors(next_rq) : 0,
-+			bfqq->entity.budget);
-+}
-+
-+/*
-+ * Return true if the process associated with bfqq is "slow". The slow
-+ * flag is used, in addition to the budget timeout, to reduce the
-+ * amount of service provided to seeky processes, and thus reduce
-+ * their chances to lower the throughput. More details in the comments
-+ * on the function bfq_bfqq_expire().
-+ *
-+ * An important observation is in order: as discussed in the comments
-+ * on the function bfq_update_peak_rate(), with devices with internal
-+ * queues, it is hard if ever possible to know when and for how long
-+ * an I/O request is processed by the device (apart from the trivial
-+ * I/O pattern where a new request is dispatched only after the
-+ * previous one has been completed). This makes it hard to evaluate
-+ * the real rate at which the I/O requests of each bfq_queue are
-+ * served.  In fact, for an I/O scheduler like BFQ, serving a
-+ * bfq_queue means just dispatching its requests during its service
-+ * slot (i.e., until the budget of the queue is exhausted, or the
-+ * queue remains idle, or, finally, a timeout fires). But, during the
-+ * service slot of a bfq_queue, around 100 ms at most, the device may
-+ * be even still processing requests of bfq_queues served in previous
-+ * service slots. On the opposite end, the requests of the in-service
-+ * bfq_queue may be completed after the service slot of the queue
-+ * finishes.
-+ *
-+ * Anyway, unless more sophisticated solutions are used
-+ * (where possible), the sum of the sizes of the requests dispatched
-+ * during the service slot of a bfq_queue is probably the only
-+ * approximation available for the service received by the bfq_queue
-+ * during its service slot. And this sum is the quantity used in this
-+ * function to evaluate the I/O speed of a process.
-+ */
-+static bool bfq_bfqq_is_slow(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+				 bool compensate, enum bfqq_expiration reason,
-+				 unsigned long *delta_ms)
-+{
-+	ktime_t delta_ktime;
-+	u32 delta_usecs;
-+	bool slow = BFQQ_SEEKY(bfqq); /* if delta too short, use seekyness */
-+
-+	if (!bfq_bfqq_sync(bfqq))
-+		return false;
-+
-+	if (compensate)
-+		delta_ktime = bfqd->last_idling_start;
-+	else
-+		delta_ktime = ktime_get();
-+	delta_ktime = ktime_sub(delta_ktime, bfqd->last_budget_start);
-+	delta_usecs = ktime_to_us(delta_ktime);
-+
-+	/* don't use too short time intervals */
-+	if (delta_usecs < 1000) {
-+		if (blk_queue_nonrot(bfqd->queue))
-+			 /*
-+			  * give same worst-case guarantees as idling
-+			  * for seeky
-+			  */
-+			*delta_ms = BFQ_MIN_TT / NSEC_PER_MSEC;
-+		else /* charge at least one seek */
-+			*delta_ms = bfq_slice_idle / NSEC_PER_MSEC;
-+
-+		bfq_log(bfqd, "too short %u", delta_usecs);
-+
-+		return slow;
-+	}
-+
-+	*delta_ms = delta_usecs / USEC_PER_MSEC;
-+
-+	/*
-+	 * Use only long (> 20ms) intervals to filter out excessive
-+	 * spikes in service rate estimation.
-+	 */
-+	if (delta_usecs > 20000) {
-+		/*
-+		 * Caveat for rotational devices: processes doing I/O
-+		 * in the slower disk zones tend to be slow(er) even
-+		 * if not seeky. In this respect, the estimated peak
-+		 * rate is likely to be an average over the disk
-+		 * surface. Accordingly, to not be too harsh with
-+		 * unlucky processes, a process is deemed slow only if
-+		 * its rate has been lower than half of the estimated
-+		 * peak rate.
-+		 */
-+		slow = bfqq->entity.service < bfqd->bfq_max_budget / 2;
-+		bfq_log(bfqd, "relative rate %d/%d",
-+			bfqq->entity.service, bfqd->bfq_max_budget);
-+	}
-+
-+	bfq_log_bfqq(bfqd, bfqq, "slow %d", slow);
-+
-+	return slow;
-+}
-+
-+/*
-+ * To be deemed as soft real-time, an application must meet two
-+ * requirements. First, the application must not require an average
-+ * bandwidth higher than the approximate bandwidth required to playback or
-+ * record a compressed high-definition video.
-+ * The next function is invoked on the completion of the last request of a
-+ * batch, to compute the next-start time instant, soft_rt_next_start, such
-+ * that, if the next request of the application does not arrive before
-+ * soft_rt_next_start, then the above requirement on the bandwidth is met.
-+ *
-+ * The second requirement is that the request pattern of the application is
-+ * isochronous, i.e., that, after issuing a request or a batch of requests,
-+ * the application stops issuing new requests until all its pending requests
-+ * have been completed. After that, the application may issue a new batch,
-+ * and so on.
-+ * For this reason the next function is invoked to compute
-+ * soft_rt_next_start only for applications that meet this requirement,
-+ * whereas soft_rt_next_start is set to infinity for applications that do
-+ * not.
-+ *
-+ * Unfortunately, even a greedy (i.e., I/O-bound) application may
-+ * happen to meet, occasionally or systematically, both the above
-+ * bandwidth and isochrony requirements. This may happen at least in
-+ * the following circumstances. First, if the CPU load is high. The
-+ * application may stop issuing requests while the CPUs are busy
-+ * serving other processes, then restart, then stop again for a while,
-+ * and so on. The other circumstances are related to the storage
-+ * device: the storage device is highly loaded or reaches a low-enough
-+ * throughput with the I/O of the application (e.g., because the I/O
-+ * is random and/or the device is slow). In all these cases, the
-+ * I/O of the application may be simply slowed down enough to meet
-+ * the bandwidth and isochrony requirements. To reduce the probability
-+ * that greedy applications are deemed as soft real-time in these
-+ * corner cases, a further rule is used in the computation of
-+ * soft_rt_next_start: the return value of this function is forced to
-+ * be higher than the maximum between the following two quantities.
-+ *
-+ * (a) Current time plus: (1) the maximum time for which the arrival
-+ *     of a request is waited for when a sync queue becomes idle,
-+ *     namely bfqd->bfq_slice_idle, and (2) a few extra jiffies. We
-+ *     postpone for a moment the reason for adding a few extra
-+ *     jiffies; we get back to it after next item (b).  Lower-bounding
-+ *     the return value of this function with the current time plus
-+ *     bfqd->bfq_slice_idle tends to filter out greedy applications,
-+ *     because the latter issue their next request as soon as possible
-+ *     after the last one has been completed. In contrast, a soft
-+ *     real-time application spends some time processing data, after a
-+ *     batch of its requests has been completed.
-+ *
-+ * (b) Current value of bfqq->soft_rt_next_start. As pointed out
-+ *     above, greedy applications may happen to meet both the
-+ *     bandwidth and isochrony requirements under heavy CPU or
-+ *     storage-device load. In more detail, in these scenarios, these
-+ *     applications happen, only for limited time periods, to do I/O
-+ *     slowly enough to meet all the requirements described so far,
-+ *     including the filtering in above item (a). These slow-speed
-+ *     time intervals are usually interspersed between other time
-+ *     intervals during which these applications do I/O at a very high
-+ *     speed. Fortunately, exactly because of the high speed of the
-+ *     I/O in the high-speed intervals, the values returned by this
-+ *     function happen to be so high, near the end of any such
-+ *     high-speed interval, to be likely to fall *after* the end of
-+ *     the low-speed time interval that follows. These high values are
-+ *     stored in bfqq->soft_rt_next_start after each invocation of
-+ *     this function. As a consequence, if the last value of
-+ *     bfqq->soft_rt_next_start is constantly used to lower-bound the
-+ *     next value that this function may return, then, from the very
-+ *     beginning of a low-speed interval, bfqq->soft_rt_next_start is
-+ *     likely to be constantly kept so high that any I/O request
-+ *     issued during the low-speed interval is considered as arriving
-+ *     to soon for the application to be deemed as soft
-+ *     real-time. Then, in the high-speed interval that follows, the
-+ *     application will not be deemed as soft real-time, just because
-+ *     it will do I/O at a high speed. And so on.
-+ *
-+ * Getting back to the filtering in item (a), in the following two
-+ * cases this filtering might be easily passed by a greedy
-+ * application, if the reference quantity was just
-+ * bfqd->bfq_slice_idle:
-+ * 1) HZ is so low that the duration of a jiffy is comparable to or
-+ *    higher than bfqd->bfq_slice_idle. This happens, e.g., on slow
-+ *    devices with HZ=100. The time granularity may be so coarse
-+ *    that the approximation, in jiffies, of bfqd->bfq_slice_idle
-+ *    is rather lower than the exact value.
-+ * 2) jiffies, instead of increasing at a constant rate, may stop increasing
-+ *    for a while, then suddenly 'jump' by several units to recover the lost
-+ *    increments. This seems to happen, e.g., inside virtual machines.
-+ * To address this issue, in the filtering in (a) we do not use as a
-+ * reference time interval just bfqd->bfq_slice_idle, but
-+ * bfqd->bfq_slice_idle plus a few jiffies. In particular, we add the
-+ * minimum number of jiffies for which the filter seems to be quite
-+ * precise also in embedded systems and KVM/QEMU virtual machines.
-+ */
-+static unsigned long bfq_bfqq_softrt_next_start(struct bfq_data *bfqd,
-+						struct bfq_queue *bfqq)
-+{
-+	bfq_log_bfqq(bfqd, bfqq,
-+"service_blkg %lu soft_rate %u sects/sec interval %u",
-+		     bfqq->service_from_backlogged,
-+		     bfqd->bfq_wr_max_softrt_rate,
-+		     jiffies_to_msecs(HZ * bfqq->service_from_backlogged /
-+				      bfqd->bfq_wr_max_softrt_rate));
-+
-+	return max3(bfqq->soft_rt_next_start,
-+		    bfqq->last_idle_bklogged +
-+		    HZ * bfqq->service_from_backlogged /
-+		    bfqd->bfq_wr_max_softrt_rate,
-+		    jiffies + nsecs_to_jiffies(bfqq->bfqd->bfq_slice_idle) + 4);
-+}
-+
-+static bool bfq_bfqq_injectable(struct bfq_queue *bfqq)
-+{
-+	return BFQQ_SEEKY(bfqq) && bfqq->wr_coeff == 1 &&
-+		blk_queue_nonrot(bfqq->bfqd->queue) &&
-+		bfqq->bfqd->hw_tag;
-+}
-+
-+/**
-+ * bfq_bfqq_expire - expire a queue.
-+ * @bfqd: device owning the queue.
-+ * @bfqq: the queue to expire.
-+ * @compensate: if true, compensate for the time spent idling.
-+ * @reason: the reason causing the expiration.
-+ *
-+ * If the process associated with bfqq does slow I/O (e.g., because it
-+ * issues random requests), we charge bfqq with the time it has been
-+ * in service instead of the service it has received (see
-+ * bfq_bfqq_charge_time for details on how this goal is achieved). As
-+ * a consequence, bfqq will typically get higher timestamps upon
-+ * reactivation, and hence it will be rescheduled as if it had
-+ * received more service than what it has actually received. In the
-+ * end, bfqq receives less service in proportion to how slowly its
-+ * associated process consumes its budgets (and hence how seriously it
-+ * tends to lower the throughput). In addition, this time-charging
-+ * strategy guarantees time fairness among slow processes. In
-+ * contrast, if the process associated with bfqq is not slow, we
-+ * charge bfqq exactly with the service it has received.
-+ *
-+ * Charging time to the first type of queues and the exact service to
-+ * the other has the effect of using the WF2Q+ policy to schedule the
-+ * former on a timeslice basis, without violating service domain
-+ * guarantees among the latter.
-+ */
-+static void bfq_bfqq_expire(struct bfq_data *bfqd,
-+			    struct bfq_queue *bfqq,
-+			    bool compensate,
-+			    enum bfqq_expiration reason)
-+{
-+	bool slow;
-+	unsigned long delta = 0;
-+	struct bfq_entity *entity = &bfqq->entity;
-+	int ref;
-+
-+	BUG_ON(bfqq != bfqd->in_service_queue);
-+
-+	/*
-+	 * Check whether the process is slow (see bfq_bfqq_is_slow).
-+	 */
-+	slow = bfq_bfqq_is_slow(bfqd, bfqq, compensate, reason, &delta);
-+
-+	/*
-+	 * As above explained, charge slow (typically seeky) and
-+	 * timed-out queues with the time and not the service
-+	 * received, to favor sequential workloads.
-+	 *
-+	 * Processes doing I/O in the slower disk zones will tend to
-+	 * be slow(er) even if not seeky. Therefore, since the
-+	 * estimated peak rate is actually an average over the disk
-+	 * surface, these processes may timeout just for bad luck. To
-+	 * avoid punishing them, do not charge time to processes that
-+	 * succeeded in consuming at least 2/3 of their budget. This
-+	 * allows BFQ to preserve enough elasticity to still perform
-+	 * bandwidth, and not time, distribution with little unlucky
-+	 * or quasi-sequential processes.
-+	 */
-+	if (bfqq->wr_coeff == 1 &&
-+	    (slow ||
-+	     (reason == BFQ_BFQQ_BUDGET_TIMEOUT &&
-+	      bfq_bfqq_budget_left(bfqq) >=  entity->budget / 3)))
-+		bfq_bfqq_charge_time(bfqd, bfqq, delta);
-+
-+	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
-+
-+	if (reason == BFQ_BFQQ_TOO_IDLE &&
-+	    entity->service <= 2 * entity->budget / 10)
-+		bfq_clear_bfqq_IO_bound(bfqq);
-+
-+	if (bfqd->low_latency && bfqq->wr_coeff == 1)
-+		bfqq->last_wr_start_finish = jiffies;
-+
-+	if (bfqd->low_latency && bfqd->bfq_wr_max_softrt_rate > 0 &&
-+	    RB_EMPTY_ROOT(&bfqq->sort_list)) {
-+		/*
-+		 * If we get here, and there are no outstanding
-+		 * requests, then the request pattern is isochronous
-+		 * (see the comments on the function
-+		 * bfq_bfqq_softrt_next_start()). Thus we can compute
-+		 * soft_rt_next_start. And we do it, unless bfqq is in
-+		 * interactive weight raising. We do not do it in the
-+		 * latter subcase, for the following reason. bfqq may
-+		 * be conveying the I/O needed to load a soft
-+		 * real-time application. Such an application will
-+		 * actually exhibit a soft real-time I/O pattern after
-+		 * it finally starts doing its job. But, if
-+		 * soft_rt_next_start is computed here for an
-+		 * interactive bfqq, and bfqq had received a lot of
-+		 * service before remaining with no outstanding
-+		 * request (likely to happen on a fast device), then
-+		 * soft_rt_next_start would be assigned such a high
-+		 * value that, for a very long time, bfqq would be
-+		 * prevented from being possibly considered as soft
-+		 * real time.
-+		 *
-+		 * If, instead, the queue still has outstanding
-+		 * requests, then we have to wait for the completion
-+		 * of all the outstanding requests to discover whether
-+		 * the request pattern is actually isochronous.
-+		 */
-+		BUG_ON(bfq_tot_busy_queues(bfqd) < 1);
-+		if (bfqq->dispatched == 0 &&
-+		    bfqq->wr_coeff != bfqd->bfq_wr_coeff) {
-+			bfqq->soft_rt_next_start =
-+				bfq_bfqq_softrt_next_start(bfqd, bfqq);
-+			bfq_log_bfqq(bfqd, bfqq, "new soft_rt_next %lu",
-+				     bfqq->soft_rt_next_start);
-+		} else if (bfqq->dispatched > 0) {
-+			/*
-+			 * Schedule an update of soft_rt_next_start to when
-+			 * the task may be discovered to be isochronous.
-+			 */
-+			bfq_mark_bfqq_softrt_update(bfqq);
-+		}
-+	}
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+	"expire (%s, slow %d, num_disp %d, short %d, weight %d, serv %d/%d)",
-+		     reason_name[reason], slow, bfqq->dispatched,
-+		     bfq_bfqq_has_short_ttime(bfqq), entity->weight,
-+		     entity->service, entity->budget);
-+
-+	/*
-+	 * Increase, decrease or leave budget unchanged according to
-+	 * reason.
-+	 */
-+	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
-+	__bfq_bfqq_recalc_budget(bfqd, bfqq, reason);
-+	BUG_ON(bfqq->next_rq == NULL &&
-+	       bfqq->entity.budget < bfqq->entity.service);
-+	ref = bfqq->ref;
-+	__bfq_bfqq_expire(bfqd, bfqq);
-+
-+	if (ref == 1) /* bfqq is gone, no more actions on it */
-+		return;
-+
-+	BUG_ON(ref > 1 &&
-+	       !bfq_bfqq_busy(bfqq) && reason == BFQ_BFQQ_BUDGET_EXHAUSTED &&
-+		!bfq_class_idle(bfqq));
-+
-+	bfqq->injected_service = 0;
-+
-+	/* mark bfqq as waiting a request only if a bic still points to it */
-+	if (!bfq_bfqq_busy(bfqq) &&
-+	    reason != BFQ_BFQQ_BUDGET_TIMEOUT &&
-+	    reason != BFQ_BFQQ_BUDGET_EXHAUSTED) {
-+		BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list));
-+		BUG_ON(bfqq->next_rq);
-+		bfq_mark_bfqq_non_blocking_wait_rq(bfqq);
-+		/*
-+		 * Not setting service to 0, because, if the next rq
-+		 * arrives in time, the queue will go on receiving
-+		 * service with this same budget (as if it never expired)
-+		 */
-+	} else {
-+		entity->service = 0;
-+		bfq_log_bfqq(bfqd, bfqq, "resetting service");
-+	}
-+
-+	/*
-+	 * Reset the received-service counter for every parent entity.
-+	 * Differently from what happens with bfqq->entity.service,
-+	 * the resetting of this counter never needs to be postponed
-+	 * for parent entities. In fact, in case bfqq may have a
-+	 * chance to go on being served using the last, partially
-+	 * consumed budget, bfqq->entity.service needs to be kept,
-+	 * because if bfqq then actually goes on being served using
-+	 * the same budget, the last value of bfqq->entity.service is
-+	 * needed to properly decrement bfqq->entity.budget by the
-+	 * portion already consumed. In contrast, it is not necessary
-+	 * to keep entity->service for parent entities too, because
-+	 * the bubble up of the new value of bfqq->entity.budget will
-+	 * make sure that the budgets of parent entities are correct,
-+	 * even in case bfqq and thus parent entities go on receiving
-+	 * service with the same budget.
-+	 */
-+	entity = entity->parent;
-+	for_each_entity(entity)
-+		entity->service = 0;
-+}
-+
-+/*
-+ * Budget timeout is not implemented through a dedicated timer, but
-+ * just checked on request arrivals and completions, as well as on
-+ * idle timer expirations.
-+ */
-+static bool bfq_bfqq_budget_timeout(struct bfq_queue *bfqq)
-+{
-+	return time_is_before_eq_jiffies(bfqq->budget_timeout);
-+}
-+
-+/*
-+ * If we expire a queue that is actively waiting (i.e., with the
-+ * device idled) for the arrival of a new request, then we may incur
-+ * the timestamp misalignment problem described in the body of the
-+ * function __bfq_activate_entity. Hence we return true only if this
-+ * condition does not hold, or if the queue is slow enough to deserve
-+ * only to be kicked off for preserving a high throughput.
-+ */
-+static bool bfq_may_expire_for_budg_timeout(struct bfq_queue *bfqq)
-+{
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		"wait_request %d left %d timeout %d",
-+		bfq_bfqq_wait_request(bfqq),
-+			bfq_bfqq_budget_left(bfqq) >=  bfqq->entity.budget / 3,
-+		bfq_bfqq_budget_timeout(bfqq));
-+
-+	return (!bfq_bfqq_wait_request(bfqq) ||
-+		bfq_bfqq_budget_left(bfqq) >=  bfqq->entity.budget / 3)
-+		&&
-+		bfq_bfqq_budget_timeout(bfqq);
-+}
-+
-+static bool idling_boosts_thr_without_issues(struct bfq_data *bfqd,
-+					     struct bfq_queue *bfqq)
-+{
-+	bool rot_without_queueing =
-+		!blk_queue_nonrot(bfqd->queue) && !bfqd->hw_tag,
-+		bfqq_sequential_and_IO_bound,
-+		idling_boosts_thr;
-+
-+	bfqq_sequential_and_IO_bound = !BFQQ_SEEKY(bfqq) &&
-+		bfq_bfqq_IO_bound(bfqq) && bfq_bfqq_has_short_ttime(bfqq);
-+	/*
-+	 * The next variable takes into account the cases where idling
-+	 * boosts the throughput.
-+	 *
-+	 * The value of the variable is computed considering, first, that
-+	 * idling is virtually always beneficial for the throughput if:
-+	 * (a) the device is not NCQ-capable and rotational, or
-+	 * (b) regardless of the presence of NCQ, the device is rotational and
-+	 *     the request pattern for bfqq is I/O-bound and sequential, or
-+	 * (c) regardless of whether it is rotational, the device is
-+	 *     not NCQ-capable and the request pattern for bfqq is
-+	 *     I/O-bound and sequential.
-+	 *
-+	 * Secondly, and in contrast to the above item (b), idling an
-+	 * NCQ-capable flash-based device would not boost the
-+	 * throughput even with sequential I/O; rather it would lower
-+	 * the throughput in proportion to how fast the device
-+	 * is. Accordingly, the next variable is true if any of the
-+	 * above conditions (a), (b) or (c) is true, and, in
-+	 * particular, happens to be false if bfqd is an NCQ-capable
-+	 * flash-based device.
-+	 */
-+	idling_boosts_thr = rot_without_queueing ||
-+		((!blk_queue_nonrot(bfqd->queue) || !bfqd->hw_tag) &&
-+		 bfqq_sequential_and_IO_bound);
-+
-+	bfq_log_bfqq(bfqd, bfqq, "idling_boosts_thr %d", idling_boosts_thr);
-+
-+	/*
-+	 * The return value of this function is equal to that of
-+	 * idling_boosts_thr, unless a special case holds. In this
-+	 * special case, described below, idling may cause problems to
-+	 * weight-raised queues.
-+	 *
-+	 * When the request pool is saturated (e.g., in the presence
-+	 * of write hogs), if the processes associated with
-+	 * non-weight-raised queues ask for requests at a lower rate,
-+	 * then processes associated with weight-raised queues have a
-+	 * higher probability to get a request from the pool
-+	 * immediately (or at least soon) when they need one. Thus
-+	 * they have a higher probability to actually get a fraction
-+	 * of the device throughput proportional to their high
-+	 * weight. This is especially true with NCQ-capable drives,
-+	 * which enqueue several requests in advance, and further
-+	 * reorder internally-queued requests.
-+	 *
-+	 * For this reason, we force to false the return value if
-+	 * there are weight-raised busy queues. In this case, and if
-+	 * bfqq is not weight-raised, this guarantees that the device
-+	 * is not idled for bfqq (if, instead, bfqq is weight-raised,
-+	 * then idling will be guaranteed by another variable, see
-+	 * below). Combined with the timestamping rules of BFQ (see
-+	 * [1] for details), this behavior causes bfqq, and hence any
-+	 * sync non-weight-raised queue, to get a lower number of
-+	 * requests served, and thus to ask for a lower number of
-+	 * requests from the request pool, before the busy
-+	 * weight-raised queues get served again. This often mitigates
-+	 * starvation problems in the presence of heavy write
-+	 * workloads and NCQ, thereby guaranteeing a higher
-+	 * application and system responsiveness in these hostile
-+	 * scenarios.
-+	 */
-+	return idling_boosts_thr &&
-+		bfqd->wr_busy_queues == 0;
-+}
-+
-+/*
-+ * There is a case where idling must be performed not for
-+ * throughput concerns, but to preserve service guarantees.
-+ *
-+ * To introduce this case, we can note that allowing the drive
-+ * to enqueue more than one request at a time, and hence
-+ * delegating de facto final scheduling decisions to the
-+ * drive's internal scheduler, entails loss of control on the
-+ * actual request service order. In particular, the critical
-+ * situation is when requests from different processes happen
-+ * to be present, at the same time, in the internal queue(s)
-+ * of the drive. In such a situation, the drive, by deciding
-+ * the service order of the internally-queued requests, does
-+ * determine also the actual throughput distribution among
-+ * these processes. But the drive typically has no notion or
-+ * concern about per-process throughput distribution, and
-+ * makes its decisions only on a per-request basis. Therefore,
-+ * the service distribution enforced by the drive's internal
-+ * scheduler is likely to coincide with the desired
-+ * device-throughput distribution only in a completely
-+ * symmetric scenario where:
-+ * (i)  each of these processes must get the same throughput as
-+ *      the others;
-+ * (ii) the I/O of each process has the same properties, in
-+ *      terms of locality (sequential or random), direction
-+ *      (reads or writes), request sizes, greediness
-+ *      (from I/O-bound to sporadic), and so on.
-+ * In fact, in such a scenario, the drive tends to treat
-+ * the requests of each of these processes in about the same
-+ * way as the requests of the others, and thus to provide
-+ * each of these processes with about the same throughput
-+ * (which is exactly the desired throughput distribution). In
-+ * contrast, in any asymmetric scenario, device idling is
-+ * certainly needed to guarantee that bfqq receives its
-+ * assigned fraction of the device throughput (see [1] for
-+ * details).
-+ * The problem is that idling may significantly reduce
-+ * throughput with certain combinations of types of I/O and
-+ * devices. An important example is sync random I/O, on flash
-+ * storage with command queueing. So, unless bfqq falls in the
-+ * above cases where idling also boosts throughput, it would
-+ * be important to check conditions (i) and (ii) accurately,
-+ * so as to avoid idling when not strictly needed for service
-+ * guarantees.
-+ *
-+ * Unfortunately, it is extremely difficult to thoroughly
-+ * check condition (ii). And, in case there are active groups,
-+ * it becomes very difficult to check condition (i) too. In
-+ * fact, if there are active groups, then, for condition (i)
-+ * to become false, it is enough that an active group contains
-+ * more active processes or sub-groups than some other active
-+ * group. More precisely, for condition (i) to hold because of
-+ * such a group, it is not even necessary that the group is
-+ * (still) active: it is sufficient that, even if the group
-+ * has become inactive, some of its descendant processes still
-+ * have some request already dispatched but still waiting for
-+ * completion. In fact, requests have still to be guaranteed
-+ * their share of the throughput even after being
-+ * dispatched. In this respect, it is easy to show that, if a
-+ * group frequently becomes inactive while still having
-+ * in-flight requests, and if, when this happens, the group is
-+ * not considered in the calculation of whether the scenario
-+ * is asymmetric, then the group may fail to be guaranteed its
-+ * fair share of the throughput (basically because idling may
-+ * not be performed for the descendant processes of the group,
-+ * but it had to be).  We address this issue with the
-+ * following bi-modal behavior, implemented in the function
-+ * bfq_symmetric_scenario().
-+ *
-+ * If there are groups with requests waiting for completion
-+ * (as commented above, some of these groups may even be
-+ * already inactive), then the scenario is tagged as
-+ * asymmetric, conservatively, without checking any of the
-+ * conditions (i) and (ii). So the device is idled for bfqq.
-+ * This behavior matches also the fact that groups are created
-+ * exactly if controlling I/O is a primary concern (to
-+ * preserve bandwidth and latency guarantees).
-+ *
-+ * On the opposite end, if there are no groups with requests
-+ * waiting for completion, then only condition (i) is actually
-+ * controlled, i.e., provided that condition (i) holds, idling
-+ * is not performed, regardless of whether condition (ii)
-+ * holds. In other words, only if condition (i) does not hold,
-+ * then idling is allowed, and the device tends to be
-+ * prevented from queueing many requests, possibly of several
-+ * processes. Since there are no groups with requests waiting
-+ * for completion, then, to control condition (i) it is enough
-+ * to check just whether all the queues with requests waiting
-+ * for completion also have the same weight.
-+ *
-+ * Not checking condition (ii) evidently exposes bfqq to the
-+ * risk of getting less throughput than its fair share.
-+ * However, for queues with the same weight, a further
-+ * mechanism, preemption, mitigates or even eliminates this
-+ * problem. And it does so without consequences on overall
-+ * throughput. This mechanism and its benefits are explained
-+ * in the next three paragraphs.
-+ *
-+ * Even if a queue, say Q, is expired when it remains idle, Q
-+ * can still preempt the new in-service queue if the next
-+ * request of Q arrives soon (see the comments on
-+ * bfq_bfqq_update_budg_for_activation). If all queues and
-+ * groups have the same weight, this form of preemption,
-+ * combined with the hole-recovery heuristic described in the
-+ * comments on function bfq_bfqq_update_budg_for_activation,
-+ * are enough to preserve a correct bandwidth distribution in
-+ * the mid term, even without idling. In fact, even if not
-+ * idling allows the internal queues of the device to contain
-+ * many requests, and thus to reorder requests, we can rather
-+ * safely assume that the internal scheduler still preserves a
-+ * minimum of mid-term fairness.
-+ *
-+ * More precisely, this preemption-based, idleless approach
-+ * provides fairness in terms of IOPS, and not sectors per
-+ * second. This can be seen with a simple example. Suppose
-+ * that there are two queues with the same weight, but that
-+ * the first queue receives requests of 8 sectors, while the
-+ * second queue receives requests of 1024 sectors. In
-+ * addition, suppose that each of the two queues contains at
-+ * most one request at a time, which implies that each queue
-+ * always remains idle after it is served. Finally, after
-+ * remaining idle, each queue receives very quickly a new
-+ * request. It follows that the two queues are served
-+ * alternatively, preempting each other if needed. This
-+ * implies that, although both queues have the same weight,
-+ * the queue with large requests receives a service that is
-+ * 1024/8 times as high as the service received by the other
-+ * queue.
-+ *
-+ * The motivation for using preemption instead of idling (for
-+ * queues with the same weight) is that, by not idling,
-+ * service guarantees are preserved (completely or at least in
-+ * part) without minimally sacrificing throughput. And, if
-+ * there is no active group, then the primary expectation for
-+ * this device is probably a high throughput.
-+ *
-+ * We are now left only with explaining the additional
-+ * compound condition that is checked below for deciding
-+ * whether the scenario is asymmetric. To explain this
-+ * compound condition, we need to add that the function
-+ * bfq_symmetric_scenario checks the weights of only
-+ * non-weight-raised queues, for efficiency reasons (see
-+ * comments on bfq_weights_tree_add()). Then the fact that
-+ * bfqq is weight-raised is checked explicitly here. More
-+ * precisely, the compound condition below takes into account
-+ * also the fact that, even if bfqq is being weight-raised,
-+ * the scenario is still symmetric if all queues with requests
-+ * waiting for completion happen to be
-+ * weight-raised. Actually, we should be even more precise
-+ * here, and differentiate between interactive weight raising
-+ * and soft real-time weight raising.
-+ *
-+ * As a side note, it is worth considering that the above
-+ * device-idling countermeasures may however fail in the
-+ * following unlucky scenario: if idling is (correctly)
-+ * disabled in a time period during which all symmetry
-+ * sub-conditions hold, and hence the device is allowed to
-+ * enqueue many requests, but at some later point in time some
-+ * sub-condition stops to hold, then it may become impossible
-+ * to let requests be served in the desired order until all
-+ * the requests already queued in the device have been served.
-+ */
-+static bool idling_needed_for_service_guarantees(struct bfq_data *bfqd,
-+						 struct bfq_queue *bfqq)
-+{
-+	bool asymmetric_scenario = (bfqq->wr_coeff > 1 &&
-+				    bfqd->wr_busy_queues <
-+				    bfq_tot_busy_queues(bfqd)) ||
-+		!bfq_symmetric_scenario(bfqd);
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+		     "wr_coeff %d wr_busy %d busy %d asymmetric %d",
-+		     bfqq->wr_coeff,
-+		     bfqd->wr_busy_queues,
-+		     bfq_tot_busy_queues(bfqd),
-+		     asymmetric_scenario);
-+
-+	return asymmetric_scenario;
-+}
-+
-+/*
-+ * For a queue that becomes empty, device idling is allowed only if
-+ * this function returns true for that queue. As a consequence, since
-+ * device idling plays a critical role for both throughput boosting
-+ * and service guarantees, the return value of this function plays a
-+ * critical role as well.
-+ *
-+ * In a nutshell, this function returns true only if idling is
-+ * beneficial for throughput or, even if detrimental for throughput,
-+ * idling is however necessary to preserve service guarantees (low
-+ * latency, desired throughput distribution, ...). In particular, on
-+ * NCQ-capable devices, this function tries to return false, so as to
-+ * help keep the drives' internal queues full, whenever this helps the
-+ * device boost the throughput without causing any service-guarantee
-+ * issue.
-+ *
-+ * Most of the issues taken into account to get the return value of
-+ * this function are not trivial. We discuss these issues in the two
-+ * functions providing the main pieces of information needed by this
-+ * function.
-+ */
-+static bool bfq_better_to_idle(struct bfq_queue *bfqq)
-+{
-+	struct bfq_data *bfqd = bfqq->bfqd;
-+	bool idling_boosts_thr_with_no_issue, idling_needed_for_service_guar;
-+
-+	if (unlikely(bfqd->strict_guarantees))
-+		return true;
-+
-+	/*
-+	 * Idling is performed only if slice_idle > 0. In addition, we
-+	 * do not idle if
-+	 * (a) bfqq is async
-+	 * (b) bfqq is in the idle io prio class: in this case we do
-+	 * not idle because we want to minimize the bandwidth that
-+	 * queues in this class can steal to higher-priority queues
-+	 */
-+	if (bfqd->bfq_slice_idle == 0 || !bfq_bfqq_sync(bfqq) ||
-+	   bfq_class_idle(bfqq))
-+		return false;
-+
-+	idling_boosts_thr_with_no_issue =
-+		idling_boosts_thr_without_issues(bfqd, bfqq);
-+
-+	idling_needed_for_service_guar =
-+		idling_needed_for_service_guarantees(bfqd, bfqq);
-+
-+	/*
-+	 * We have now the two components we need to compute the
-+	 * return value of the function, which is true only if idling
-+	 * either boosts the throughput (without issues), or is
-+	 * necessary to preserve service guarantees.
-+	 */
-+	bfq_log_bfqq(bfqd, bfqq,
-+		     "wr_busy %d boosts %d IO-bound %d guar %d",
-+		     bfqd->wr_busy_queues,
-+		     idling_boosts_thr_with_no_issue,
-+		     bfq_bfqq_IO_bound(bfqq),
-+		     idling_needed_for_service_guar);
-+
-+	return idling_boosts_thr_with_no_issue ||
-+		idling_needed_for_service_guar;
-+}
-+
-+/*
-+ * If the in-service queue is empty but the function bfq_better_to_idle
-+ * returns true, then:
-+ * 1) the queue must remain in service and cannot be expired, and
-+ * 2) the device must be idled to wait for the possible arrival of a new
-+ *    request for the queue.
-+ * See the comments on the function bfq_better_to_idle for the reasons
-+ * why performing device idling is the best choice to boost the throughput
-+ * and preserve service guarantees when bfq_better_to_idle itself
-+ * returns true.
-+ */
-+static bool bfq_bfqq_must_idle(struct bfq_queue *bfqq)
-+{
-+	return RB_EMPTY_ROOT(&bfqq->sort_list) && bfq_better_to_idle(bfqq);
-+}
-+
-+static struct bfq_queue *bfq_choose_bfqq_for_injection(struct bfq_data *bfqd)
-+{
-+	struct bfq_queue *bfqq;
-+
-+	/*
-+	 * A linear search; but, with a high probability, very few
-+	 * steps are needed to find a candidate queue, i.e., a queue
-+	 * with enough budget left for its next request. In fact:
-+	 * - BFQ dynamically updates the budget of every queue so as
-+	 *   to accomodate the expected backlog of the queue;
-+	 * - if a queue gets all its requests dispatched as injected
-+	 *   service, then the queue is removed from the active list
-+	 *   (and re-added only if it gets new requests, but with
-+	 *   enough budget for its new backlog).
-+	 */
-+	list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list)
-+		if (!RB_EMPTY_ROOT(&bfqq->sort_list) &&
-+		    bfq_serv_to_charge(bfqq->next_rq, bfqq) <=
-+		    bfq_bfqq_budget_left(bfqq)) {
-+			bfq_log_bfqq(bfqd, bfqq, "returned this queue");
-+			return bfqq;
-+		}
-+
-+	bfq_log(bfqd, "no queue found");
-+	return NULL;
-+}
-+
-+/*
-+ * Select a queue for service.  If we have a current queue in service,
-+ * check whether to continue servicing it, or retrieve and set a new one.
-+ */
-+static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd)
-+{
-+	struct bfq_queue *bfqq;
-+	struct request *next_rq;
-+	enum bfqq_expiration reason = BFQ_BFQQ_BUDGET_TIMEOUT;
-+
-+	bfqq = bfqd->in_service_queue;
-+	if (!bfqq)
-+		goto new_queue;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "already in-service queue");
-+
-+	/*
-+	 * Do not expire bfqq for budget timeout if bfqq may be about
-+	 * to enjoy device idling. The reason why, in this case, we
-+	 * prevent bfqq from expiring is the same as in the comments
-+	 * on the case where bfq_bfqq_must_idle() returns true, in
-+	 * bfq_completed_request().
-+	 */
-+	if (bfq_may_expire_for_budg_timeout(bfqq) &&
-+	    !bfq_bfqq_must_idle(bfqq))
-+		goto expire;
-+
-+check_queue:
-+	/*
-+	 * This loop is rarely executed more than once. Even when it
-+	 * happens, it is much more convenient to re-execute this loop
-+	 * than to return NULL and trigger a new dispatch to get a
-+	 * request served.
-+	 */
-+	next_rq = bfqq->next_rq;
-+	/*
-+	 * If bfqq has requests queued and it has enough budget left to
-+	 * serve them, keep the queue, otherwise expire it.
-+	 */
-+	if (next_rq) {
-+		BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list));
-+
-+		if (bfq_serv_to_charge(next_rq, bfqq) >
-+			bfq_bfqq_budget_left(bfqq)) {
-+			/*
-+			 * Expire the queue for budget exhaustion,
-+			 * which makes sure that the next budget is
-+			 * enough to serve the next request, even if
-+			 * it comes from the fifo expired path.
-+			 */
-+			reason = BFQ_BFQQ_BUDGET_EXHAUSTED;
-+			goto expire;
-+		} else {
-+			/*
-+			 * The idle timer may be pending because we may
-+			 * not disable disk idling even when a new request
-+			 * arrives.
-+			 */
-+			if (bfq_bfqq_wait_request(bfqq)) {
-+				/*
-+				 * If we get here: 1) at least a new request
-+				 * has arrived but we have not disabled the
-+				 * timer because the request was too small,
-+				 * 2) then the block layer has unplugged
-+				 * the device, causing the dispatch to be
-+				 * invoked.
-+				 *
-+				 * Since the device is unplugged, now the
-+				 * requests are probably large enough to
-+				 * provide a reasonable throughput.
-+				 * So we disable idling.
-+				 */
-+				bfq_clear_bfqq_wait_request(bfqq);
-+				hrtimer_try_to_cancel(&bfqd->idle_slice_timer);
-+			}
-+			goto keep_queue;
-+		}
-+	}
-+
-+	/*
-+	 * No requests pending. However, if the in-service queue is idling
-+	 * for a new request, or has requests waiting for a completion and
-+	 * may idle after their completion, then keep it anyway.
-+	 *
-+	 * Yet, to boost throughput, inject service from other queues if
-+	 * possible.
-+	 */
-+	if (bfq_bfqq_wait_request(bfqq) ||
-+	    (bfqq->dispatched != 0 && bfq_better_to_idle(bfqq))) {
-+		if (bfq_bfqq_injectable(bfqq) &&
-+		    bfqq->injected_service * bfqq->inject_coeff <
-+		    bfqq->entity.service * 10) {
-+			bfq_log_bfqq(bfqd, bfqq, "looking for queue for injection");
-+			bfqq = bfq_choose_bfqq_for_injection(bfqd);
-+		} else {
-+			if (BFQQ_SEEKY(bfqq))
-+				bfq_log_bfqq(bfqd, bfqq,
-+					"injection saturated %d * %d >= %d * 10",
-+					bfqq->injected_service, bfqq->inject_coeff,
-+					bfqq->entity.service);
-+			bfqq = NULL;
-+		}
-+		goto keep_queue;
-+	}
-+
-+	reason = BFQ_BFQQ_NO_MORE_REQUESTS;
-+expire:
-+	bfq_bfqq_expire(bfqd, bfqq, false, reason);
-+new_queue:
-+	bfqq = bfq_set_in_service_queue(bfqd);
-+	if (bfqq) {
-+		bfq_log_bfqq(bfqd, bfqq, "checking new queue");
-+		goto check_queue;
-+	}
-+keep_queue:
-+	if (bfqq)
-+		bfq_log_bfqq(bfqd, bfqq, "returned this queue");
-+	else
-+		bfq_log(bfqd, "no queue returned");
-+
-+	return bfqq;
-+}
-+
-+static void bfq_update_wr_data(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+
-+	if (bfqq->wr_coeff > 1) { /* queue is being weight-raised */
-+		BUG_ON(bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time &&
-+		       time_is_after_jiffies(bfqq->last_wr_start_finish));
-+
-+		bfq_log_bfqq(bfqd, bfqq,
-+			"raising period dur %u/%u msec, old coeff %u, w %d(%d)",
-+			jiffies_to_msecs(jiffies - bfqq->last_wr_start_finish),
-+			jiffies_to_msecs(bfqq->wr_cur_max_time),
-+			bfqq->wr_coeff,
-+			bfqq->entity.weight, bfqq->entity.orig_weight);
-+
-+		BUG_ON(bfqq != bfqd->in_service_queue && entity->weight !=
-+		       entity->orig_weight * bfqq->wr_coeff);
-+		if (entity->prio_changed)
-+			bfq_log_bfqq(bfqd, bfqq, "WARN: pending prio change");
-+
-+		/*
-+		 * If the queue was activated in a burst, or too much
-+		 * time has elapsed from the beginning of this
-+		 * weight-raising period, then end weight raising.
-+		 */
-+		if (bfq_bfqq_in_large_burst(bfqq))
-+			bfq_bfqq_end_wr(bfqq);
-+		else if (time_is_before_jiffies(bfqq->last_wr_start_finish +
-+					   bfqq->wr_cur_max_time)) {
-+			if (bfqq->wr_cur_max_time != bfqd->bfq_wr_rt_max_time ||
-+			time_is_before_jiffies(bfqq->wr_start_at_switch_to_srt +
-+					bfq_wr_duration(bfqd)))
-+				bfq_bfqq_end_wr(bfqq);
-+			else {
-+				switch_back_to_interactive_wr(bfqq, bfqd);
-+				BUG_ON(time_is_after_jiffies(
-+					       bfqq->last_wr_start_finish));
-+				bfqq->entity.prio_changed = 1;
-+				bfq_log_bfqq(bfqd, bfqq,
-+					"back to interactive wr");
-+			}
-+		}
-+		if (bfqq->wr_coeff > 1 &&
-+		    bfqq->wr_cur_max_time != bfqd->bfq_wr_rt_max_time &&
-+		    bfqq->service_from_wr > max_service_from_wr) {
-+			/* see comments on max_service_from_wr */
-+			bfq_bfqq_end_wr(bfqq);
-+			bfq_log_bfqq(bfqd, bfqq,
-+				     "too much service");
-+		}
-+	}
-+	/*
-+	 * To improve latency (for this or other queues), immediately
-+	 * update weight both if it must be raised and if it must be
-+	 * lowered. Since, entity may be on some active tree here, and
-+	 * might have a pending change of its ioprio class, invoke
-+	 * next function with the last parameter unset (see the
-+	 * comments on the function).
-+	 */
-+	if ((entity->weight > entity->orig_weight) != (bfqq->wr_coeff > 1))
-+		__bfq_entity_update_weight_prio(bfq_entity_service_tree(entity),
-+						entity, false);
-+}
-+
-+/*
-+ * Dispatch next request from bfqq.
-+ */
-+static struct request *bfq_dispatch_rq_from_bfqq(struct bfq_data *bfqd,
-+						 struct bfq_queue *bfqq)
-+{
-+	struct request *rq = bfqq->next_rq;
-+	unsigned long service_to_charge;
-+
-+	BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list));
-+	BUG_ON(!rq);
-+	service_to_charge = bfq_serv_to_charge(rq, bfqq);
-+
-+	BUG_ON(service_to_charge > bfq_bfqq_budget_left(bfqq));
-+
-+	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
-+
-+	bfq_bfqq_served(bfqq, service_to_charge);
-+
-+	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
-+
-+	bfq_dispatch_remove(bfqd->queue, rq);
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+	     "dispatched %u sec req (%llu), budg left %d, new disp_nr %d",
-+			blk_rq_sectors(rq),
-+			(unsigned long long) blk_rq_pos(rq),
-+		     bfq_bfqq_budget_left(bfqq),
-+		     bfqq->dispatched);
-+
-+	if (bfqq != bfqd->in_service_queue) {
-+		if (likely(bfqd->in_service_queue)) {
-+			bfqd->in_service_queue->injected_service +=
-+				bfq_serv_to_charge(rq, bfqq);
-+			bfq_log_bfqq(bfqd, bfqd->in_service_queue,
-+				     "injected_service increased to %d",
-+				     bfqd->in_service_queue->injected_service);
-+		}
-+		goto return_rq;
-+	}
-+
-+	/*
-+	 * If weight raising has to terminate for bfqq, then next
-+	 * function causes an immediate update of bfqq's weight,
-+	 * without waiting for next activation. As a consequence, on
-+	 * expiration, bfqq will be timestamped as if has never been
-+	 * weight-raised during this service slot, even if it has
-+	 * received part or even most of the service as a
-+	 * weight-raised queue. This inflates bfqq's timestamps, which
-+	 * is beneficial, as bfqq is then more willing to leave the
-+	 * device immediately to possible other weight-raised queues.
-+	 */
-+	bfq_update_wr_data(bfqd, bfqq);
-+
-+	/*
-+	 * Expire bfqq, pretending that its budget expired, if bfqq
-+	 * belongs to CLASS_IDLE and other queues are waiting for
-+	 * service.
-+	 */
-+	if (!(bfq_tot_busy_queues(bfqd) > 1 && bfq_class_idle(bfqq)))
-+		goto return_rq;
-+
-+	bfq_bfqq_expire(bfqd, bfqq, false, BFQ_BFQQ_BUDGET_EXHAUSTED);
-+
-+return_rq:
-+	return rq;
-+}
-+
-+static bool bfq_has_work(struct blk_mq_hw_ctx *hctx)
-+{
-+	struct bfq_data *bfqd = hctx->queue->elevator->elevator_data;
-+
-+	bfq_log(bfqd, "dispatch_non_empty %d busy_queues %d",
-+		!list_empty_careful(&bfqd->dispatch), bfq_tot_busy_queues(bfqd) > 0);
-+
-+	/*
-+	 * Avoiding lock: a race on bfqd->busy_queues should cause at
-+	 * most a call to dispatch for nothing
-+	 */
-+	return !list_empty_careful(&bfqd->dispatch) ||
-+		bfq_tot_busy_queues(bfqd) > 0;
-+}
-+
-+static struct request *__bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
-+{
-+	struct bfq_data *bfqd = hctx->queue->elevator->elevator_data;
-+	struct request *rq = NULL;
-+	struct bfq_queue *bfqq = NULL;
-+
-+	if (!list_empty(&bfqd->dispatch)) {
-+		rq = list_first_entry(&bfqd->dispatch, struct request,
-+				      queuelist);
-+		list_del_init(&rq->queuelist);
-+		rq->rq_flags &= ~RQF_DISP_LIST;
-+
-+		bfq_log(bfqd,
-+			"picked %p from dispatch list", rq);
-+		bfqq = RQ_BFQQ(rq);
-+
-+		if (bfqq) {
-+			/*
-+			 * Increment counters here, because this
-+			 * dispatch does not follow the standard
-+			 * dispatch flow (where counters are
-+			 * incremented)
-+			 */
-+			bfqq->dispatched++;
-+
-+			/*
-+			 * TESTING: reset DISP_LIST flag, because: 1)
-+			 * this rq this request has passed through
-+			 * bfq_prepare_request, 2) then it will have
-+			 * bfq_finish_requeue_request invoked on it, and 3) in
-+			 * bfq_finish_requeue_request we use this flag to check
-+			 * that bfq_finish_requeue_request is not invoked on
-+			 * requests for which bfq_prepare_request has
-+			 * been invoked.
-+			 */
-+			rq->rq_flags &= ~RQF_DISP_LIST;
-+			goto inc_in_driver_start_rq;
-+		}
-+
-+		/*
-+		 * We exploit the bfq_finish_requeue_request hook to decrement
-+		 * rq_in_driver, but bfq_finish_requeue_request will not be
-+		 * invoked on this request. So, to avoid unbalance,
-+		 * just start this request, without incrementing
-+		 * rq_in_driver. As a negative consequence,
-+		 * rq_in_driver is deceptively lower than it should be
-+		 * while this request is in service. This may cause
-+		 * bfq_schedule_dispatch to be invoked uselessly.
-+		 *
-+		 * As for implementing an exact solution, the
-+		 * bfq_finish_requeue_request hook, if defined, is probably
-+		 * invoked also on this request. So, by exploiting
-+		 * this hook, we could 1) increment rq_in_driver here,
-+		 * and 2) decrement it in bfq_finish_requeue_request. Such a
-+		 * solution would let the value of the counter be
-+		 * always accurate, but it would entail using an extra
-+		 * interface function. This cost seems higher than the
-+		 * benefit, being the frequency of non-elevator-private
-+		 * requests very low.
-+		 */
-+		goto start_rq;
-+	}
-+
-+	bfq_log(bfqd, "%d busy queues", bfq_tot_busy_queues(bfqd));
-+
-+	if (bfq_tot_busy_queues(bfqd) == 0)
-+		goto exit;
-+
-+	/*
-+	 * Force device to serve one request at a time if
-+	 * strict_guarantees is true. Forcing this service scheme is
-+	 * currently the ONLY way to guarantee that the request
-+	 * service order enforced by the scheduler is respected by a
-+	 * queueing device. Otherwise the device is free even to make
-+	 * some unlucky request wait for as long as the device
-+	 * wishes.
-+	 *
-+	 * Of course, serving one request at at time may cause loss of
-+	 * throughput.
-+	 */
-+	if (bfqd->strict_guarantees && bfqd->rq_in_driver > 0)
-+		goto exit;
-+
-+	bfqq = bfq_select_queue(bfqd);
-+	if (!bfqq)
-+		goto exit;
-+
-+	BUG_ON(bfqq == bfqd->in_service_queue &&
-+	       bfqq->entity.budget < bfqq->entity.service);
-+
-+	BUG_ON(bfqq == bfqd->in_service_queue &&
-+	       bfq_bfqq_wait_request(bfqq));
-+
-+	rq = bfq_dispatch_rq_from_bfqq(bfqd, bfqq);
-+
-+	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
-+
-+	if (rq) {
-+	inc_in_driver_start_rq:
-+		bfqd->rq_in_driver++;
-+	start_rq:
-+		rq->rq_flags |= RQF_STARTED;
-+		if (bfqq)
-+			bfq_log_bfqq(bfqd, bfqq,
-+				"%s request %p, rq_in_driver %d",
-+				     bfq_bfqq_sync(bfqq) ? "sync" : "async",
-+				     rq,
-+				     bfqd->rq_in_driver);
-+		else
-+			bfq_log(bfqd,
-+		"request %p from dispatch list, rq_in_driver %d",
-+				rq, bfqd->rq_in_driver);
-+	} else
-+		bfq_log(bfqd,
-+		"returned NULL request, rq_in_driver %d",
-+			bfqd->rq_in_driver);
-+
-+exit:
-+	return rq;
-+}
-+
-+
-+#if defined(BFQ_GROUP_IOSCHED_ENABLED) && defined(CONFIG_DEBUG_BLK_CGROUP)
-+static void bfq_update_dispatch_stats(struct request_queue *q,
-+				      struct request *rq,
-+				      struct bfq_queue *in_serv_queue,
-+				      bool idle_timer_disabled)
-+{
-+	struct bfq_queue *bfqq = rq ? RQ_BFQQ(rq) : NULL;
-+
-+	if (!idle_timer_disabled && !bfqq)
-+		return;
-+
-+	/*
-+	 * rq and bfqq are guaranteed to exist until this function
-+	 * ends, for the following reasons. First, rq can be
-+	 * dispatched to the device, and then can be completed and
-+	 * freed, only after this function ends. Second, rq cannot be
-+	 * merged (and thus freed because of a merge) any longer,
-+	 * because it has already started. Thus rq cannot be freed
-+	 * before this function ends, and, since rq has a reference to
-+	 * bfqq, the same guarantee holds for bfqq too.
-+	 *
-+	 * In addition, the following queue lock guarantees that
-+	 * bfqq_group(bfqq) exists as well.
-+	 */
-+	spin_lock_irq(q->queue_lock);
-+	if (idle_timer_disabled)
-+		/*
-+		 * Since the idle timer has been disabled,
-+		 * in_serv_queue contained some request when
-+		 * __bfq_dispatch_request was invoked above, which
-+		 * implies that rq was picked exactly from
-+		 * in_serv_queue. Thus in_serv_queue == bfqq, and is
-+		 * therefore guaranteed to exist because of the above
-+		 * arguments.
-+		 */
-+		bfqg_stats_update_idle_time(bfqq_group(in_serv_queue));
-+	if (bfqq) {
-+		struct bfq_group *bfqg = bfqq_group(bfqq);
-+
-+		bfqg_stats_update_avg_queue_size(bfqg);
-+		bfqg_stats_set_start_empty_time(bfqg);
-+		bfqg_stats_update_io_remove(bfqg, rq->cmd_flags);
-+	}
-+	spin_unlock_irq(q->queue_lock);
-+}
-+#else
-+static inline void bfq_update_dispatch_stats(struct request_queue *q,
-+					     struct request *rq,
-+					     struct bfq_queue *in_serv_queue,
-+					     bool idle_timer_disabled) {}
-+#endif
-+static struct request *bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
-+{
-+	struct bfq_data *bfqd = hctx->queue->elevator->elevator_data;
-+	struct request *rq;
-+	struct bfq_queue *in_serv_queue;
-+	bool waiting_rq, idle_timer_disabled;
-+
-+	spin_lock_irq(&bfqd->lock);
-+
-+	in_serv_queue = bfqd->in_service_queue;
-+	waiting_rq = in_serv_queue && bfq_bfqq_wait_request(in_serv_queue);
-+
-+	rq = __bfq_dispatch_request(hctx);
-+
-+	idle_timer_disabled =
-+		waiting_rq && !bfq_bfqq_wait_request(in_serv_queue);
-+
-+	spin_unlock_irq(&bfqd->lock);
-+
-+	bfq_update_dispatch_stats(hctx->queue, rq, in_serv_queue,
-+				  idle_timer_disabled);
-+
-+	return rq;
-+}
-+
-+/*
-+ * Task holds one reference to the queue, dropped when task exits.  Each rq
-+ * in-flight on this queue also holds a reference, dropped when rq is freed.
-+ *
-+ * Scheduler lock must be held here. Recall not to use bfqq after calling
-+ * this function on it.
-+ */
-+static void bfq_put_queue(struct bfq_queue *bfqq)
-+{
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	struct bfq_group *bfqg = bfqq_group(bfqq);
-+#endif
-+
-+	assert_spin_locked(&bfqq->bfqd->lock);
-+
-+	BUG_ON(bfqq->ref <= 0);
-+
-+	if (bfqq->bfqd)
-+		bfq_log_bfqq(bfqq->bfqd, bfqq, "%p %d", bfqq, bfqq->ref);
-+
-+	bfqq->ref--;
-+	if (bfqq->ref)
-+		return;
-+
-+	BUG_ON(rb_first(&bfqq->sort_list));
-+	BUG_ON(bfqq->allocated != 0);
-+	BUG_ON(bfqq->entity.tree);
-+	BUG_ON(bfq_bfqq_busy(bfqq));
-+
-+	if (!hlist_unhashed(&bfqq->burst_list_node)) {
-+		hlist_del_init(&bfqq->burst_list_node);
-+		/*
-+		 * Decrement also burst size after the removal, if the
-+		 * process associated with bfqq is exiting, and thus
-+		 * does not contribute to the burst any longer. This
-+		 * decrement helps filter out false positives of large
-+		 * bursts, when some short-lived process (often due to
-+		 * the execution of commands by some service) happens
-+		 * to start and exit while a complex application is
-+		 * starting, and thus spawning several processes that
-+		 * do I/O (and that *must not* be treated as a large
-+		 * burst, see comments on bfq_handle_burst).
-+		 *
-+		 * In particular, the decrement is performed only if:
-+		 * 1) bfqq is not a merged queue, because, if it is,
-+		 * then this free of bfqq is not triggered by the exit
-+		 * of the process bfqq is associated with, but exactly
-+		 * by the fact that bfqq has just been merged.
-+		 * 2) burst_size is greater than 0, to handle
-+		 * unbalanced decrements. Unbalanced decrements may
-+		 * happen in te following case: bfqq is inserted into
-+		 * the current burst list--without incrementing
-+		 * bust_size--because of a split, but the current
-+		 * burst list is not the burst list bfqq belonged to
-+		 * (see comments on the case of a split in
-+		 * bfq_set_request).
-+		 */
-+		if (bfqq->bic && bfqq->bfqd->burst_size > 0)
-+			bfqq->bfqd->burst_size--;
-+	}
-+
-+	if (bfqq->bfqd)
-+		bfq_log_bfqq(bfqq->bfqd, bfqq, "%p freed", bfqq);
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "putting blkg and bfqg %p\n", bfqg);
-+	bfqg_and_blkg_put(bfqg);
-+#endif
-+	kmem_cache_free(bfq_pool, bfqq);
-+}
-+
-+static void bfq_put_cooperator(struct bfq_queue *bfqq)
-+{
-+	struct bfq_queue *__bfqq, *next;
-+
-+	/*
-+	 * If this queue was scheduled to merge with another queue, be
-+	 * sure to drop the reference taken on that queue (and others in
-+	 * the merge chain). See bfq_setup_merge and bfq_merge_bfqqs.
-+	 */
-+	__bfqq = bfqq->new_bfqq;
-+	while (__bfqq) {
-+		if (__bfqq == bfqq)
-+			break;
-+		next = __bfqq->new_bfqq;
-+		bfq_put_queue(__bfqq);
-+		__bfqq = next;
-+	}
-+}
-+
-+static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	if (bfqq == bfqd->in_service_queue) {
-+		__bfq_bfqq_expire(bfqd, bfqq);
-+		bfq_schedule_dispatch(bfqd);
-+	}
-+
-+	bfq_log_bfqq(bfqd, bfqq, "%p, %d", bfqq, bfqq->ref);
-+
-+	bfq_put_cooperator(bfqq);
-+
-+	bfq_put_queue(bfqq); /* release process reference */
-+}
-+
-+static void bfq_exit_icq_bfqq(struct bfq_io_cq *bic, bool is_sync)
-+{
-+	struct bfq_queue *bfqq = bic_to_bfqq(bic, is_sync);
-+	struct bfq_data *bfqd;
-+
-+	if (bfqq)
-+		bfqd = bfqq->bfqd; /* NULL if scheduler already exited */
-+
-+	if (bfqq && bfqd) {
-+		unsigned long flags;
-+
-+		spin_lock_irqsave(&bfqd->lock, flags);
-+		bfq_exit_bfqq(bfqd, bfqq);
-+		bic_set_bfqq(bic, NULL, is_sync);
-+		spin_unlock_irqrestore(&bfqd->lock, flags);
-+	}
-+}
-+
-+static void bfq_exit_icq(struct io_cq *icq)
-+{
-+	struct bfq_io_cq *bic = icq_to_bic(icq);
-+
-+	BUG_ON(!bic);
-+	bfq_exit_icq_bfqq(bic, true);
-+	bfq_exit_icq_bfqq(bic, false);
-+}
-+
-+/*
-+ * Update the entity prio values; note that the new values will not
-+ * be used until the next (re)activation.
-+ */
-+static void bfq_set_next_ioprio_data(struct bfq_queue *bfqq,
-+				     struct bfq_io_cq *bic)
-+{
-+	struct task_struct *tsk = current;
-+	int ioprio_class;
-+	struct bfq_data *bfqd = bfqq->bfqd;
-+
-+	WARN_ON(!bfqd);
-+	if (!bfqd)
-+		return;
-+
-+	ioprio_class = IOPRIO_PRIO_CLASS(bic->ioprio);
-+	switch (ioprio_class) {
-+	default:
-+		dev_err(bfqq->bfqd->queue->backing_dev_info->dev,
-+			"bfq: bad prio class %d\n", ioprio_class);
-+	case IOPRIO_CLASS_NONE:
-+		/*
-+		 * No prio set, inherit CPU scheduling settings.
-+		 */
-+		bfqq->new_ioprio = task_nice_ioprio(tsk);
-+		bfqq->new_ioprio_class = task_nice_ioclass(tsk);
-+		break;
-+	case IOPRIO_CLASS_RT:
-+		bfqq->new_ioprio = IOPRIO_PRIO_DATA(bic->ioprio);
-+		bfqq->new_ioprio_class = IOPRIO_CLASS_RT;
-+		break;
-+	case IOPRIO_CLASS_BE:
-+		bfqq->new_ioprio = IOPRIO_PRIO_DATA(bic->ioprio);
-+		bfqq->new_ioprio_class = IOPRIO_CLASS_BE;
-+		break;
-+	case IOPRIO_CLASS_IDLE:
-+		bfqq->new_ioprio_class = IOPRIO_CLASS_IDLE;
-+		bfqq->new_ioprio = 7;
-+		break;
-+	}
-+
-+	if (bfqq->new_ioprio >= IOPRIO_BE_NR) {
-+		pr_crit("bfq_set_next_ioprio_data: new_ioprio %d\n",
-+			bfqq->new_ioprio);
-+		BUG();
-+	}
-+
-+	bfqq->entity.new_weight = bfq_ioprio_to_weight(bfqq->new_ioprio);
-+	bfqq->entity.prio_changed = 1;
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		     "bic_class %d prio %d class %d",
-+		     ioprio_class, bfqq->new_ioprio, bfqq->new_ioprio_class);
-+}
-+
-+static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio)
-+{
-+	struct bfq_data *bfqd = bic_to_bfqd(bic);
-+	struct bfq_queue *bfqq;
-+	unsigned long uninitialized_var(flags);
-+	int ioprio = bic->icq.ioc->ioprio;
-+
-+	/*
-+	 * This condition may trigger on a newly created bic, be sure to
-+	 * drop the lock before returning.
-+	 */
-+	if (unlikely(!bfqd) || likely(bic->ioprio == ioprio))
-+		return;
-+
-+	bic->ioprio = ioprio;
-+
-+	bfqq = bic_to_bfqq(bic, false);
-+	if (bfqq) {
-+		/* release process reference on this queue */
-+		bfq_put_queue(bfqq);
-+		bfqq = bfq_get_queue(bfqd, bio, BLK_RW_ASYNC, bic);
-+		bic_set_bfqq(bic, bfqq, false);
-+		bfq_log_bfqq(bfqd, bfqq,
-+			     "bfqq %p %d",
-+			     bfqq, bfqq->ref);
-+	}
-+
-+	bfqq = bic_to_bfqq(bic, true);
-+	if (bfqq)
-+		bfq_set_next_ioprio_data(bfqq, bic);
-+}
-+
-+static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+			  struct bfq_io_cq *bic, pid_t pid, int is_sync)
-+{
-+	RB_CLEAR_NODE(&bfqq->entity.rb_node);
-+	INIT_LIST_HEAD(&bfqq->fifo);
-+	INIT_HLIST_NODE(&bfqq->burst_list_node);
-+	BUG_ON(!hlist_unhashed(&bfqq->burst_list_node));
-+
-+	bfqq->ref = 0;
-+	bfqq->bfqd = bfqd;
-+
-+	if (bic)
-+		bfq_set_next_ioprio_data(bfqq, bic);
-+
-+	if (is_sync) {
-+		/*
-+		 * No need to mark as has_short_ttime if in
-+		 * idle_class, because no device idling is performed
-+		 * for queues in idle class
-+		 */
-+		if (!bfq_class_idle(bfqq))
-+			/* tentatively mark as has_short_ttime */
-+			bfq_mark_bfqq_has_short_ttime(bfqq);
-+		bfq_mark_bfqq_sync(bfqq);
-+		bfq_mark_bfqq_just_created(bfqq);
-+		/*
-+		 * Aggressively inject a lot of service: up to 90%.
-+		 * This coefficient remains constant during bfqq life,
-+		 * but this behavior might be changed, after enough
-+		 * testing and tuning.
-+		 */
-+		bfqq->inject_coeff = 1;
-+	} else
-+		bfq_clear_bfqq_sync(bfqq);
-+
-+	bfqq->ttime.last_end_request = ktime_get_ns() - (1ULL<<32);
-+
-+	bfq_mark_bfqq_IO_bound(bfqq);
-+
-+	/* Tentative initial value to trade off between thr and lat */
-+	bfqq->max_budget = (2 * bfq_max_budget(bfqd)) / 3;
-+	bfqq->pid = pid;
-+
-+	bfqq->wr_coeff = 1;
-+	bfqq->last_wr_start_finish = jiffies;
-+	bfqq->wr_start_at_switch_to_srt = bfq_smallest_from_now();
-+	bfqq->budget_timeout = bfq_smallest_from_now();
-+	bfqq->split_time = bfq_smallest_from_now();
-+
-+	/*
-+	 * To not forget the possibly high bandwidth consumed by a
-+	 * process/queue in the recent past,
-+	 * bfq_bfqq_softrt_next_start() returns a value at least equal
-+	 * to the current value of bfqq->soft_rt_next_start (see
-+	 * comments on bfq_bfqq_softrt_next_start).  Set
-+	 * soft_rt_next_start to now, to mean that bfqq has consumed
-+	 * no bandwidth so far.
-+	 */
-+	bfqq->soft_rt_next_start = jiffies;
-+
-+	/* first request is almost certainly seeky */
-+	bfqq->seek_history = 1;
-+}
-+
-+static struct bfq_queue **bfq_async_queue_prio(struct bfq_data *bfqd,
-+					       struct bfq_group *bfqg,
-+					       int ioprio_class, int ioprio)
-+{
-+	switch (ioprio_class) {
-+	case IOPRIO_CLASS_RT:
-+		return &bfqg->async_bfqq[0][ioprio];
-+	case IOPRIO_CLASS_NONE:
-+		ioprio = IOPRIO_NORM;
-+		/* fall through */
-+	case IOPRIO_CLASS_BE:
-+		return &bfqg->async_bfqq[1][ioprio];
-+	case IOPRIO_CLASS_IDLE:
-+		return &bfqg->async_idle_bfqq;
-+	default:
-+		BUG();
-+	}
-+}
-+
-+static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd,
-+				       struct bio *bio, bool is_sync,
-+				       struct bfq_io_cq *bic)
-+{
-+	const int ioprio = IOPRIO_PRIO_DATA(bic->ioprio);
-+	const int ioprio_class = IOPRIO_PRIO_CLASS(bic->ioprio);
-+	struct bfq_queue **async_bfqq = NULL;
-+	struct bfq_queue *bfqq;
-+	struct bfq_group *bfqg;
-+
-+	rcu_read_lock();
-+
-+	bfqg = bfq_find_set_group(bfqd, bio_blkcg(bio));
-+	if (!bfqg) {
-+		bfqq = &bfqd->oom_bfqq;
-+		goto out;
-+	}
-+
-+	if (!is_sync) {
-+		async_bfqq = bfq_async_queue_prio(bfqd, bfqg, ioprio_class,
-+						  ioprio);
-+		bfqq = *async_bfqq;
-+		if (bfqq)
-+			goto out;
-+	}
-+
-+	bfqq = kmem_cache_alloc_node(bfq_pool,
-+				     GFP_NOWAIT | __GFP_ZERO | __GFP_NOWARN,
-+				     bfqd->queue->node);
-+
-+	if (bfqq) {
-+		bfq_init_bfqq(bfqd, bfqq, bic, current->pid,
-+			      is_sync);
-+		bfq_init_entity(&bfqq->entity, bfqg);
-+		bfq_log_bfqq(bfqd, bfqq, "allocated");
-+	} else {
-+		bfqq = &bfqd->oom_bfqq;
-+		bfq_log_bfqq(bfqd, bfqq, "using oom bfqq");
-+		goto out;
-+	}
-+
-+	/*
-+	 * Pin the queue now that it's allocated, scheduler exit will
-+	 * prune it.
-+	 */
-+	if (async_bfqq) {
-+		bfqq->ref++; /*
-+			      * Extra group reference, w.r.t. sync
-+			      * queue. This extra reference is removed
-+			      * only if bfqq->bfqg disappears, to
-+			      * guarantee that this queue is not freed
-+			      * until its group goes away.
-+			      */
-+		bfq_log_bfqq(bfqd, bfqq, "bfqq not in async: %p, %d",
-+			     bfqq, bfqq->ref);
-+		*async_bfqq = bfqq;
-+	}
-+
-+out:
-+	bfqq->ref++; /* get a process reference to this queue */
-+	bfq_log_bfqq(bfqd, bfqq, "at end: %p, %d", bfqq, bfqq->ref);
-+	rcu_read_unlock();
-+	return bfqq;
-+}
-+
-+static void bfq_update_io_thinktime(struct bfq_data *bfqd,
-+				    struct bfq_queue *bfqq)
-+{
-+	struct bfq_ttime *ttime = &bfqq->ttime;
-+	u64 elapsed = ktime_get_ns() - bfqq->ttime.last_end_request;
-+
-+	elapsed = min_t(u64, elapsed, 2 * bfqd->bfq_slice_idle);
-+
-+	ttime->ttime_samples = (7*bfqq->ttime.ttime_samples + 256) / 8;
-+	ttime->ttime_total = div_u64(7*ttime->ttime_total + 256*elapsed,  8);
-+	ttime->ttime_mean = div64_ul(ttime->ttime_total + 128,
-+				     ttime->ttime_samples);
-+}
-+
-+static void
-+bfq_update_io_seektime(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+		       struct request *rq)
-+{
-+	bfqq->seek_history <<= 1;
-+	bfqq->seek_history |= BFQ_RQ_SEEKY(bfqd, bfqq->last_request_pos, rq);
-+}
-+
-+static void bfq_update_has_short_ttime(struct bfq_data *bfqd,
-+				       struct bfq_queue *bfqq,
-+				       struct bfq_io_cq *bic)
-+{
-+	bool has_short_ttime = true;
-+
-+	/*
-+	 * No need to update has_short_ttime if bfqq is async or in
-+	 * idle io prio class, or if bfq_slice_idle is zero, because
-+	 * no device idling is performed for bfqq in this case.
-+	 */
-+	if (!bfq_bfqq_sync(bfqq) || bfq_class_idle(bfqq) ||
-+	    bfqd->bfq_slice_idle == 0)
-+		return;
-+
-+	/* Idle window just restored, statistics are meaningless. */
-+	if (time_is_after_eq_jiffies(bfqq->split_time +
-+				     bfqd->bfq_wr_min_idle_time))
-+		return;
-+
-+	/* Think time is infinite if no process is linked to
-+	 * bfqq. Otherwise check average think time to
-+	 * decide whether to mark as has_short_ttime
-+	 */
-+	if (atomic_read(&bic->icq.ioc->active_ref) == 0 ||
-+	    (bfq_sample_valid(bfqq->ttime.ttime_samples) &&
-+	     bfqq->ttime.ttime_mean > bfqd->bfq_slice_idle))
-+		has_short_ttime = false;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "has_short_ttime %d",
-+		has_short_ttime);
-+
-+	if (has_short_ttime)
-+		bfq_mark_bfqq_has_short_ttime(bfqq);
-+	else
-+		bfq_clear_bfqq_has_short_ttime(bfqq);
-+}
-+
-+/*
-+ * Called when a new fs request (rq) is added to bfqq.  Check if there's
-+ * something we should do about it.
-+ */
-+static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+			    struct request *rq)
-+{
-+	struct bfq_io_cq *bic = RQ_BIC(rq);
-+
-+	if (rq->cmd_flags & REQ_META)
-+		bfqq->meta_pending++;
-+
-+	bfq_update_io_thinktime(bfqd, bfqq);
-+	bfq_update_has_short_ttime(bfqd, bfqq, bic);
-+	bfq_update_io_seektime(bfqd, bfqq, rq);
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+		     "has_short_ttime=%d (seeky %d)",
-+		     bfq_bfqq_has_short_ttime(bfqq), BFQQ_SEEKY(bfqq));
-+
-+	bfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
-+
-+	if (bfqq == bfqd->in_service_queue && bfq_bfqq_wait_request(bfqq)) {
-+		bool small_req = bfqq->queued[rq_is_sync(rq)] == 1 &&
-+				 blk_rq_sectors(rq) < 32;
-+		bool budget_timeout = bfq_bfqq_budget_timeout(bfqq);
-+
-+		/*
-+		 * There is just this request queued: if
-+		 * - the request is small, and
-+		 * - we are idling to boost throughput, and
-+		 * - the queue is not to be expired,
-+		 * then just exit.
-+		 *
-+		 * In this way, if the device is being idled to wait
-+		 * for a new request from the in-service queue, we
-+		 * avoid unplugging the device and committing the
-+		 * device to serve just a small request. In contrast
-+		 * we wait for the block layer to decide when to
-+		 * unplug the device: hopefully, new requests will be
-+		 * merged to this one quickly, then the device will be
-+		 * unplugged and larger requests will be dispatched.
-+		 */
-+		if (small_req && idling_boosts_thr_without_issues(bfqd, bfqq) &&
-+		    !budget_timeout)
-+			return;
-+
-+		/*
-+		 * A large enough request arrived, or idling is being
-+		 * performed to preserve service guarantees, or
-+		 * finally the queue is to be expired: in all these
-+		 * cases disk idling is to be stopped, so clear
-+		 * wait_request flag and reset timer.
-+		 */
-+		bfq_clear_bfqq_wait_request(bfqq);
-+		hrtimer_try_to_cancel(&bfqd->idle_slice_timer);
-+
-+		/*
-+		 * The queue is not empty, because a new request just
-+		 * arrived. Hence we can safely expire the queue, in
-+		 * case of budget timeout, without risking that the
-+		 * timestamps of the queue are not updated correctly.
-+		 * See [1] for more details.
-+		 */
-+		if (budget_timeout)
-+			bfq_bfqq_expire(bfqd, bfqq, false,
-+					BFQ_BFQQ_BUDGET_TIMEOUT);
-+	}
-+}
-+
-+/* returns true if it causes the idle timer to be disabled */
-+static bool __bfq_insert_request(struct bfq_data *bfqd, struct request *rq)
-+{
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq), *new_bfqq;
-+	bool waiting, idle_timer_disabled = false;
-+	BUG_ON(!bfqq);
-+
-+	assert_spin_locked(&bfqd->lock);
-+
-+	bfq_log_bfqq(bfqd, bfqq, "rq %p bfqq %p", rq, bfqq);
-+
-+	/*
-+	 * An unplug may trigger a requeue of a request from the device
-+	 * driver: make sure we are in process context while trying to
-+	 * merge two bfq_queues.
-+	 */
-+	if (!in_interrupt()) {
-+		new_bfqq = bfq_setup_cooperator(bfqd, bfqq, rq, true);
-+		if (new_bfqq) {
-+			BUG_ON(bic_to_bfqq(RQ_BIC(rq), 1) != bfqq);
-+			/*
-+			 * Release the request's reference to the old bfqq
-+			 * and make sure one is taken to the shared queue.
-+			 */
-+			new_bfqq->allocated++;
-+			bfqq->allocated--;
-+			bfq_log_bfqq(bfqd, bfqq,
-+		     "new allocated %d", bfqq->allocated);
-+			bfq_log_bfqq(bfqd, new_bfqq,
-+		     "new_bfqq new allocated %d",
-+				     bfqq->allocated);
-+
-+			new_bfqq->ref++;
-+			/*
-+			 * If the bic associated with the process
-+			 * issuing this request still points to bfqq
-+			 * (and thus has not been already redirected
-+			 * to new_bfqq or even some other bfq_queue),
-+			 * then complete the merge and redirect it to
-+			 * new_bfqq.
-+			 */
-+			if (bic_to_bfqq(RQ_BIC(rq), 1) == bfqq)
-+				bfq_merge_bfqqs(bfqd, RQ_BIC(rq),
-+						bfqq, new_bfqq);
-+
-+			bfq_clear_bfqq_just_created(bfqq);
-+			/*
-+			 * rq is about to be enqueued into new_bfqq,
-+			 * release rq reference on bfqq
-+			 */
-+			bfq_put_queue(bfqq);
-+			rq->elv.priv[1] = new_bfqq;
-+			bfqq = new_bfqq;
-+		}
-+	}
-+
-+	waiting = bfqq && bfq_bfqq_wait_request(bfqq);
-+	bfq_add_request(rq);
-+	idle_timer_disabled = waiting && !bfq_bfqq_wait_request(bfqq);
-+
-+	rq->fifo_time = ktime_get_ns() + bfqd->bfq_fifo_expire[rq_is_sync(rq)];
-+	list_add_tail(&rq->queuelist, &bfqq->fifo);
-+
-+	bfq_rq_enqueued(bfqd, bfqq, rq);
-+
-+	return idle_timer_disabled;
-+}
-+
-+#if defined(BFQ_GROUP_IOSCHED_ENABLED) && defined(CONFIG_DEBUG_BLK_CGROUP)
-+static void bfq_update_insert_stats(struct request_queue *q,
-+				    struct bfq_queue *bfqq,
-+				    bool idle_timer_disabled,
-+				    unsigned int cmd_flags)
-+{
-+	if (!bfqq)
-+		return;
-+
-+	/*
-+	 * bfqq still exists, because it can disappear only after
-+	 * either it is merged with another queue, or the process it
-+	 * is associated with exits. But both actions must be taken by
-+	 * the same process currently executing this flow of
-+	 * instructions.
-+	 *
-+	 * In addition, the following queue lock guarantees that
-+	 * bfqq_group(bfqq) exists as well.
-+	 */
-+	spin_lock_irq(q->queue_lock);
-+	bfqg_stats_update_io_add(bfqq_group(bfqq), bfqq, cmd_flags);
-+	if (idle_timer_disabled)
-+		bfqg_stats_update_idle_time(bfqq_group(bfqq));
-+	spin_unlock_irq(q->queue_lock);
-+}
-+#else
-+static inline void bfq_update_insert_stats(struct request_queue *q,
-+					   struct bfq_queue *bfqq,
-+					   bool idle_timer_disabled,
-+					   unsigned int cmd_flags) {}
-+#endif
-+
-+static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
-+			       bool at_head)
-+{
-+	struct request_queue *q = hctx->queue;
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	struct bfq_queue *bfqq;
-+	bool idle_timer_disabled = false;
-+	unsigned int cmd_flags;
-+
-+	spin_lock_irq(&bfqd->lock);
-+	if (blk_mq_sched_try_insert_merge(q, rq)) {
-+		spin_unlock_irq(&bfqd->lock);
-+		return;
-+	}
-+
-+	spin_unlock_irq(&bfqd->lock);
-+
-+	blk_mq_sched_request_inserted(rq);
-+
-+	spin_lock_irq(&bfqd->lock);
-+
-+	bfqq = bfq_init_rq(rq);
-+	BUG_ON(!bfqq && !(at_head || blk_rq_is_passthrough(rq)));
-+	BUG_ON(bfqq && bic_to_bfqq(RQ_BIC(rq), rq_is_sync(rq)) != bfqq);
-+
-+	if (at_head || blk_rq_is_passthrough(rq)) {
-+		if (at_head)
-+			list_add(&rq->queuelist, &bfqd->dispatch);
-+		else
-+			list_add_tail(&rq->queuelist, &bfqd->dispatch);
-+
-+		rq->rq_flags |= RQF_DISP_LIST;
-+		if (bfqq)
-+			bfq_log_bfqq(bfqd, bfqq,
-+				     "%p in disp: at_head %d",
-+				     rq, at_head);
-+		else
-+			bfq_log(bfqd,
-+				"%p in disp: at_head %d",
-+				rq, at_head);
-+	} else { /* bfqq is assumed to be non null here */
-+		BUG_ON(!bfqq);
-+		BUG_ON(!(rq->rq_flags & RQF_GOT));
-+		rq->rq_flags &= ~RQF_GOT;
-+
-+		idle_timer_disabled = __bfq_insert_request(bfqd, rq);
-+		/*
-+		 * Update bfqq, because, if a queue merge has occurred
-+		 * in __bfq_insert_request, then rq has been
-+		 * redirected into a new queue.
-+		 */
-+		bfqq = RQ_BFQQ(rq);
-+
-+		if (rq_mergeable(rq)) {
-+			elv_rqhash_add(q, rq);
-+			if (!q->last_merge)
-+				q->last_merge = rq;
-+		}
-+	}
-+
-+	/*
-+	 * Cache cmd_flags before releasing scheduler lock, because rq
-+	 * may disappear afterwards (for example, because of a request
-+	 * merge).
-+	 */
-+	cmd_flags = rq->cmd_flags;
-+
-+	spin_unlock_irq(&bfqd->lock);
-+	bfq_update_insert_stats(q, bfqq, idle_timer_disabled,
-+				cmd_flags);
-+}
-+
-+static void bfq_insert_requests(struct blk_mq_hw_ctx *hctx,
-+				struct list_head *list, bool at_head)
-+{
-+	while (!list_empty(list)) {
-+		struct request *rq;
-+
-+		rq = list_first_entry(list, struct request, queuelist);
-+		list_del_init(&rq->queuelist);
-+		bfq_insert_request(hctx, rq, at_head);
-+	}
-+}
-+
-+static void bfq_update_hw_tag(struct bfq_data *bfqd)
-+{
-+	struct bfq_queue *bfqq = bfqd->in_service_queue;
-+
-+	bfqd->max_rq_in_driver = max_t(int, bfqd->max_rq_in_driver,
-+				       bfqd->rq_in_driver);
-+
-+	if (bfqd->hw_tag == 1)
-+		return;
-+
-+	/*
-+	 * This sample is valid if the number of outstanding requests
-+	 * is large enough to allow a queueing behavior.  Note that the
-+	 * sum is not exact, as it's not taking into account deactivated
-+	 * requests.
-+	 */
-+	if (bfqd->rq_in_driver + bfqd->queued <= BFQ_HW_QUEUE_THRESHOLD)
-+		return;
-+
-+	/*
-+	 * If active queue hasn't enough requests and can idle, bfq might not
-+	 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
-+	 * case
-+	 */
-+	if (bfqq && bfq_bfqq_has_short_ttime(bfqq) &&
-+	    bfqq->dispatched + bfqq->queued[0] + bfqq->queued[1] <
-+	    BFQ_HW_QUEUE_THRESHOLD && bfqd->rq_in_driver < BFQ_HW_QUEUE_THRESHOLD)
-+		return;
-+
-+	if (bfqd->hw_tag_samples++ < BFQ_HW_QUEUE_SAMPLES)
-+		return;
-+
-+	bfqd->hw_tag = bfqd->max_rq_in_driver > BFQ_HW_QUEUE_THRESHOLD;
-+	bfqd->max_rq_in_driver = 0;
-+	bfqd->hw_tag_samples = 0;
-+}
-+
-+static void bfq_completed_request(struct bfq_queue *bfqq, struct bfq_data *bfqd)
-+{
-+	u64 now_ns;
-+	u32 delta_us;
-+
-+	bfq_update_hw_tag(bfqd);
-+
-+	BUG_ON(!bfqd->rq_in_driver);
-+	BUG_ON(!bfqq->dispatched);
-+	bfqd->rq_in_driver--;
-+	bfqq->dispatched--;
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+		     "new disp %d, new rq_in_driver %d",
-+		     bfqq->dispatched, bfqd->rq_in_driver);
-+
-+	if (!bfqq->dispatched && !bfq_bfqq_busy(bfqq)) {
-+		BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list));
-+		/*
-+		 * Set budget_timeout (which we overload to store the
-+		 * time at which the queue remains with no backlog and
-+		 * no outstanding request; used by the weight-raising
-+		 * mechanism).
-+		 */
-+		bfqq->budget_timeout = jiffies;
-+
-+		bfq_weights_tree_remove(bfqd, bfqq);
-+	}
-+
-+	now_ns = ktime_get_ns();
-+
-+	bfqq->ttime.last_end_request = now_ns;
-+
-+	/*
-+	 * Using us instead of ns, to get a reasonable precision in
-+	 * computing rate in next check.
-+	 */
-+	delta_us = div_u64(now_ns - bfqd->last_completion, NSEC_PER_USEC);
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+		"delta %uus/%luus max_size %u rate %llu/%llu",
-+		delta_us, BFQ_MIN_TT/NSEC_PER_USEC, bfqd->last_rq_max_size,
-+		delta_us > 0 ?
-+		(USEC_PER_SEC*
-+		(u64)((bfqd->last_rq_max_size<<BFQ_RATE_SHIFT)/delta_us))
-+			>>BFQ_RATE_SHIFT :
-+		(USEC_PER_SEC*
-+		(u64)(bfqd->last_rq_max_size<<BFQ_RATE_SHIFT))>>BFQ_RATE_SHIFT,
-+		(USEC_PER_SEC*(u64)(1UL<<(BFQ_RATE_SHIFT-10)))>>BFQ_RATE_SHIFT);
-+
-+	/*
-+	 * If the request took rather long to complete, and, according
-+	 * to the maximum request size recorded, this completion latency
-+	 * implies that the request was certainly served at a very low
-+	 * rate (less than 1M sectors/sec), then the whole observation
-+	 * interval that lasts up to this time instant cannot be a
-+	 * valid time interval for computing a new peak rate.  Invoke
-+	 * bfq_update_rate_reset to have the following three steps
-+	 * taken:
-+	 * - close the observation interval at the last (previous)
-+	 *   request dispatch or completion
-+	 * - compute rate, if possible, for that observation interval
-+	 * - reset to zero samples, which will trigger a proper
-+	 *   re-initialization of the observation interval on next
-+	 *   dispatch
-+	 */
-+	if (delta_us > BFQ_MIN_TT/NSEC_PER_USEC &&
-+	   (bfqd->last_rq_max_size<<BFQ_RATE_SHIFT)/delta_us <
-+			1UL<<(BFQ_RATE_SHIFT - 10))
-+		bfq_update_rate_reset(bfqd, NULL);
-+	bfqd->last_completion = now_ns;
-+
-+	/*
-+	 * If we are waiting to discover whether the request pattern
-+	 * of the task associated with the queue is actually
-+	 * isochronous, and both requisites for this condition to hold
-+	 * are now satisfied, then compute soft_rt_next_start (see the
-+	 * comments on the function bfq_bfqq_softrt_next_start()). We
-+	 * do not compute soft_rt_next_start if bfqq is in interactive
-+	 * weight raising (see the comments in bfq_bfqq_expire() for
-+	 * an explanation). We schedule this delayed update when bfqq
-+	 * expires, if it still has in-flight requests.
-+	 */
-+	if (bfq_bfqq_softrt_update(bfqq) && bfqq->dispatched == 0 &&
-+	    RB_EMPTY_ROOT(&bfqq->sort_list) &&
-+	    bfqq->wr_coeff != bfqd->bfq_wr_coeff)
-+		bfqq->soft_rt_next_start =
-+			bfq_bfqq_softrt_next_start(bfqd, bfqq);
-+
-+	/*
-+	 * If this is the in-service queue, check if it needs to be expired,
-+	 * or if we want to idle in case it has no pending requests.
-+	 */
-+	if (bfqd->in_service_queue == bfqq) {
-+		if (bfq_bfqq_must_idle(bfqq)) {
-+			if (bfqq->dispatched == 0)
-+				bfq_arm_slice_timer(bfqd);
-+			/*
-+			 * If we get here, we do not expire bfqq, even
-+			 * if bfqq was in budget timeout or had no
-+			 * more requests (as controlled in the next
-+			 * conditional instructions). The reason for
-+			 * not expiring bfqq is as follows.
-+			 *
-+			 * Here bfqq->dispatched > 0 holds, but
-+			 * bfq_bfqq_must_idle() returned true. This
-+			 * implies that, even if no request arrives
-+			 * for bfqq before bfqq->dispatched reaches 0,
-+			 * bfqq will, however, not be expired on the
-+			 * completion event that causes bfqq->dispatch
-+			 * to reach zero. In contrast, on this event,
-+			 * bfqq will start enjoying device idling
-+			 * (I/O-dispatch plugging).
-+			 *
-+			 * But, if we expired bfqq here, bfqq would
-+			 * not have the chance to enjoy device idling
-+			 * when bfqq->dispatched finally reaches
-+			 * zero. This would expose bfqq to violation
-+			 * of its reserved service guarantees.
-+			 */
-+			return;
-+		} else if (bfq_may_expire_for_budg_timeout(bfqq))
-+			bfq_bfqq_expire(bfqd, bfqq, false,
-+					BFQ_BFQQ_BUDGET_TIMEOUT);
-+		else if (RB_EMPTY_ROOT(&bfqq->sort_list) &&
-+			 (bfqq->dispatched == 0 ||
-+			  !bfq_better_to_idle(bfqq)))
-+			bfq_bfqq_expire(bfqd, bfqq, false,
-+					BFQ_BFQQ_NO_MORE_REQUESTS);
-+	}
-+}
-+
-+static void bfq_finish_requeue_request_body(struct bfq_queue *bfqq)
-+{
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		     "allocated %d", bfqq->allocated);
-+	BUG_ON(!bfqq->allocated);
-+	bfqq->allocated--;
-+
-+	bfq_put_queue(bfqq);
-+}
-+
-+/*
-+ * Handle either a requeue or a finish for rq. The things to do are
-+ * the same in both cases: all references to rq are to be dropped. In
-+ * particular, rq is considered completed from the point of view of
-+ * the scheduler.
-+ */
-+static void bfq_finish_requeue_request(struct request *rq)
-+{
-+	struct bfq_queue *bfqq;
-+	struct bfq_data *bfqd;
-+	struct bfq_io_cq *bic;
-+
-+	BUG_ON(!rq);
-+
-+	bfqq = RQ_BFQQ(rq);
-+
-+	/*
-+	 * Requeue and finish hooks are invoked in blk-mq without
-+	 * checking whether the involved request is actually still
-+	 * referenced in the scheduler. To handle this fact, the
-+	 * following two checks make this function exit in case of
-+	 * spurious invocations, for which there is nothing to do.
-+	 *
-+	 * First, check whether rq has nothing to do with an elevator.
-+	 */
-+	if (unlikely(!(rq->rq_flags & RQF_ELVPRIV)))
-+		return;
-+
-+	/*
-+	 * rq either is not associated with any icq, or is an already
-+	 * requeued request that has not (yet) been re-inserted into
-+	 * a bfq_queue.
-+	 */
-+	if (!rq->elv.icq || !bfqq)
-+		return;
-+
-+	bic = RQ_BIC(rq);
-+	BUG_ON(!bic);
-+
-+	bfqd = bfqq->bfqd;
-+	BUG_ON(!bfqd);
-+
-+	if (rq->rq_flags & RQF_DISP_LIST) {
-+		pr_crit("putting disp rq %p for %d", rq, bfqq->pid);
-+		BUG();
-+	}
-+	BUG_ON(rq->rq_flags & RQF_QUEUED);
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+		     "putting rq %p with %u sects left, STARTED %d",
-+		     rq, blk_rq_sectors(rq),
-+		     rq->rq_flags & RQF_STARTED);
-+
-+	if (rq->rq_flags & RQF_STARTED)
-+		bfqg_stats_update_completion(bfqq_group(bfqq),
-+					     rq->start_time_ns,
-+					     rq->io_start_time_ns,
-+					     rq->cmd_flags);
-+
-+	WARN_ON(blk_rq_sectors(rq) == 0 && !(rq->rq_flags & RQF_STARTED));
-+
-+	if (likely(rq->rq_flags & RQF_STARTED)) {
-+		unsigned long flags;
-+
-+		spin_lock_irqsave(&bfqd->lock, flags);
-+
-+		bfq_completed_request(bfqq, bfqd);
-+		bfq_finish_requeue_request_body(bfqq);
-+
-+		spin_unlock_irqrestore(&bfqd->lock, flags);
-+	} else {
-+		/*
-+		 * Request rq may be still/already in the scheduler,
-+		 * in which case we need to remove it (this should
-+		 * never happen in case of requeue). And we cannot
-+		 * defer such a check and removal, to avoid
-+		 * inconsistencies in the time interval from the end
-+		 * of this function to the start of the deferred work.
-+		 * This situation seems to occur only in process
-+		 * context, as a consequence of a merge. In the
-+		 * current version of the code, this implies that the
-+		 * lock is held.
-+		 */
-+		BUG_ON(in_interrupt());
-+
-+		assert_spin_locked(&bfqd->lock);
-+		if (!RB_EMPTY_NODE(&rq->rb_node)) {
-+			bfq_remove_request(rq->q, rq);
-+			bfqg_stats_update_io_remove(bfqq_group(bfqq),
-+						    rq->cmd_flags);
-+		}
-+		bfq_finish_requeue_request_body(bfqq);
-+	}
-+
-+	/*
-+	 * Reset private fields. In case of a requeue, this allows
-+	 * this function to correctly do nothing if it is spuriously
-+	 * invoked again on this same request (see the check at the
-+	 * beginning of the function). Probably, a better general
-+	 * design would be to prevent blk-mq from invoking the requeue
-+	 * or finish hooks of an elevator, for a request that is not
-+	 * referred by that elevator.
-+	 *
-+	 * Resetting the following fields would break the
-+	 * request-insertion logic if rq is re-inserted into a bfq
-+	 * internal queue, without a re-preparation. Here we assume
-+	 * that re-insertions of requeued requests, without
-+	 * re-preparation, can happen only for pass_through or at_head
-+	 * requests (which are not re-inserted into bfq internal
-+	 * queues).
-+	 */
-+	rq->elv.priv[0] = NULL;
-+	rq->elv.priv[1] = NULL;
-+}
-+
-+/*
-+ * Returns NULL if a new bfqq should be allocated, or the old bfqq if this
-+ * was the last process referring to that bfqq.
-+ */
-+static struct bfq_queue *
-+bfq_split_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq)
-+{
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "splitting queue");
-+
-+	if (bfqq_process_refs(bfqq) == 1) {
-+		bfqq->pid = current->pid;
-+		bfq_clear_bfqq_coop(bfqq);
-+		bfq_clear_bfqq_split_coop(bfqq);
-+		return bfqq;
-+	}
-+
-+	bic_set_bfqq(bic, NULL, 1);
-+
-+	bfq_put_cooperator(bfqq);
-+
-+	bfq_put_queue(bfqq);
-+	return NULL;
-+}
-+
-+static struct bfq_queue *bfq_get_bfqq_handle_split(struct bfq_data *bfqd,
-+						   struct bfq_io_cq *bic,
-+						   struct bio *bio,
-+						   bool split, bool is_sync,
-+						   bool *new_queue)
-+{
-+	struct bfq_queue *bfqq = bic_to_bfqq(bic, is_sync);
-+
-+	if (likely(bfqq && bfqq != &bfqd->oom_bfqq))
-+		return bfqq;
-+
-+	if (new_queue)
-+		*new_queue = true;
-+
-+	if (bfqq)
-+		bfq_put_queue(bfqq);
-+	bfqq = bfq_get_queue(bfqd, bio, is_sync, bic);
-+	BUG_ON(!hlist_unhashed(&bfqq->burst_list_node));
-+
-+	bic_set_bfqq(bic, bfqq, is_sync);
-+	if (split && is_sync) {
-+		bfq_log_bfqq(bfqd, bfqq,
-+			     "get_request: was_in_list %d "
-+			     "was_in_large_burst %d "
-+			     "large burst in progress %d",
-+			     bic->was_in_burst_list,
-+			     bic->saved_in_large_burst,
-+			     bfqd->large_burst);
-+
-+		if ((bic->was_in_burst_list && bfqd->large_burst) ||
-+		    bic->saved_in_large_burst) {
-+			bfq_log_bfqq(bfqd, bfqq,
-+				     "get_request: marking in "
-+				     "large burst");
-+			bfq_mark_bfqq_in_large_burst(bfqq);
-+		} else {
-+			bfq_log_bfqq(bfqd, bfqq,
-+				     "get_request: clearing in "
-+				     "large burst");
-+			bfq_clear_bfqq_in_large_burst(bfqq);
-+			if (bic->was_in_burst_list)
-+				/*
-+				 * If bfqq was in the current
-+				 * burst list before being
-+				 * merged, then we have to add
-+				 * it back. And we do not need
-+				 * to increase burst_size, as
-+				 * we did not decrement
-+				 * burst_size when we removed
-+				 * bfqq from the burst list as
-+				 * a consequence of a merge
-+				 * (see comments in
-+				 * bfq_put_queue). In this
-+				 * respect, it would be rather
-+				 * costly to know whether the
-+				 * current burst list is still
-+				 * the same burst list from
-+				 * which bfqq was removed on
-+				 * the merge. To avoid this
-+				 * cost, if bfqq was in a
-+				 * burst list, then we add
-+				 * bfqq to the current burst
-+				 * list without any further
-+				 * check. This can cause
-+				 * inappropriate insertions,
-+				 * but rarely enough to not
-+				 * harm the detection of large
-+				 * bursts significantly.
-+				 */
-+				hlist_add_head(&bfqq->burst_list_node,
-+					       &bfqd->burst_list);
-+		}
-+		bfqq->split_time = jiffies;
-+	}
-+
-+	return bfqq;
-+}
-+
-+/*
-+ * Only reset private fields. The actual request preparation will be
-+ * performed by bfq_init_rq, when rq is either inserted or merged. See
-+ * comments on bfq_init_rq for the reason behind this delayed
-+ * preparation.
-+*/
-+static void bfq_prepare_request(struct request *rq, struct bio *bio)
-+{
-+	/*
-+	 * Regardless of whether we have an icq attached, we have to
-+	 * clear the scheduler pointers, as they might point to
-+	 * previously allocated bic/bfqq structs.
-+	 */
-+	rq->elv.priv[0] = rq->elv.priv[1] = NULL;
-+}
-+
-+/*
-+ * If needed, init rq, allocate bfq data structures associated with
-+ * rq, and increment reference counters in the destination bfq_queue
-+ * for rq. Return the destination bfq_queue for rq, or NULL is rq is
-+ * not associated with any bfq_queue.
-+ *
-+ * This function is invoked by the functions that perform rq insertion
-+ * or merging. One may have expected the above preparation operations
-+ * to be performed in bfq_prepare_request, and not delayed to when rq
-+ * is inserted or merged. The rationale behind this delayed
-+ * preparation is that, after the prepare_request hook is invoked for
-+ * rq, rq may still be transformed into a request with no icq, i.e., a
-+ * request not associated with any queue. No bfq hook is invoked to
-+ * signal this tranformation. As a consequence, should these
-+ * preparation operations be performed when the prepare_request hook
-+ * is invoked, and should rq be transformed one moment later, bfq
-+ * would end up in an inconsistent state, because it would have
-+ * incremented some queue counters for an rq destined to
-+ * transformation, without any chance to correctly lower these
-+ * counters back. In contrast, no transformation can still happen for
-+ * rq after rq has been inserted or merged. So, it is safe to execute
-+ * these preparation operations when rq is finally inserted or merged.
-+ */
-+static struct bfq_queue *bfq_init_rq(struct request *rq)
-+{
-+	struct request_queue *q = rq->q;
-+	struct bio *bio = rq->bio;
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	struct bfq_io_cq *bic;
-+	const int is_sync = rq_is_sync(rq);
-+	struct bfq_queue *bfqq;
-+	bool bfqq_already_existing = false, split = false;
-+	bool new_queue = false;
-+
-+	if (unlikely(!rq->elv.icq))
-+		return NULL;
-+
-+	/*
-+	 * Assuming that elv.priv[1] is set only if everything is set
-+	 * for this rq. This holds true, because this function is
-+	 * invoked only for insertion or merging, and, after such
-+	 * events, a request cannot be manipulated any longer before
-+	 * being removed from bfq.
-+	 */
-+	if (rq->elv.priv[1]) {
-+		BUG_ON(!(rq->rq_flags & RQF_ELVPRIV));
-+		return rq->elv.priv[1];
-+	}
-+
-+	bic = icq_to_bic(rq->elv.icq);
-+
-+	bfq_check_ioprio_change(bic, bio);
-+
-+	bfq_bic_update_cgroup(bic, bio);
-+
-+	bfqq = bfq_get_bfqq_handle_split(bfqd, bic, bio, false, is_sync,
-+					 &new_queue);
-+
-+	if (likely(!new_queue)) {
-+		/* If the queue was seeky for too long, break it apart. */
-+		if (bfq_bfqq_coop(bfqq) && bfq_bfqq_split_coop(bfqq)) {
-+			BUG_ON(!is_sync);
-+			bfq_log_bfqq(bfqd, bfqq, "breaking apart bfqq");
-+
-+			/* Update bic before losing reference to bfqq */
-+			if (bfq_bfqq_in_large_burst(bfqq))
-+				bic->saved_in_large_burst = true;
-+
-+			bfqq = bfq_split_bfqq(bic, bfqq);
-+			split = true;
-+
-+			if (!bfqq)
-+				bfqq = bfq_get_bfqq_handle_split(bfqd, bic, bio,
-+								 true, is_sync,
-+								 NULL);
-+			else
-+				bfqq_already_existing = true;
-+
-+			BUG_ON(!bfqq);
-+			BUG_ON(bfqq == &bfqd->oom_bfqq);
-+		}
-+	}
-+
-+	bfqq->allocated++;
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		     "new allocated %d", bfqq->allocated);
-+
-+	bfqq->ref++;
-+	bfq_log_bfqq(bfqd, bfqq, "%p: bfqq %p, %d", rq, bfqq, bfqq->ref);
-+
-+	rq->elv.priv[0] = bic;
-+	rq->elv.priv[1] = bfqq;
-+	rq->rq_flags &= ~RQF_DISP_LIST;
-+
-+	/*
-+	 * If a bfq_queue has only one process reference, it is owned
-+	 * by only this bic: we can then set bfqq->bic = bic. in
-+	 * addition, if the queue has also just been split, we have to
-+	 * resume its state.
-+	 */
-+	if (likely(bfqq != &bfqd->oom_bfqq) && bfqq_process_refs(bfqq) == 1) {
-+		bfqq->bic = bic;
-+		if (split) {
-+			/*
-+			 * The queue has just been split from a shared
-+			 * queue: restore the idle window and the
-+			 * possible weight raising period.
-+			 */
-+			bfq_bfqq_resume_state(bfqq, bfqd, bic,
-+					      bfqq_already_existing);
-+		}
-+	}
-+
-+	if (unlikely(bfq_bfqq_just_created(bfqq)))
-+		bfq_handle_burst(bfqd, bfqq);
-+
-+	rq->rq_flags |= RQF_GOT;
-+
-+	return bfqq;
-+}
-+
-+static void bfq_idle_slice_timer_body(struct bfq_queue *bfqq)
-+{
-+	struct bfq_data *bfqd = bfqq->bfqd;
-+	enum bfqq_expiration reason;
-+	unsigned long flags;
-+
-+	BUG_ON(!bfqd);
-+	spin_lock_irqsave(&bfqd->lock, flags);
-+
-+	bfq_log_bfqq(bfqd, bfqq, "handling slice_timer expiration");
-+	bfq_clear_bfqq_wait_request(bfqq);
-+
-+	if (bfqq != bfqd->in_service_queue) {
-+		spin_unlock_irqrestore(&bfqd->lock, flags);
-+		return;
-+	}
-+
-+	if (bfq_bfqq_budget_timeout(bfqq))
-+		/*
-+		 * Also here the queue can be safely expired
-+		 * for budget timeout without wasting
-+		 * guarantees
-+		 */
-+		reason = BFQ_BFQQ_BUDGET_TIMEOUT;
-+	else if (bfqq->queued[0] == 0 && bfqq->queued[1] == 0)
-+		/*
-+		 * The queue may not be empty upon timer expiration,
-+		 * because we may not disable the timer when the
-+		 * first request of the in-service queue arrives
-+		 * during disk idling.
-+		 */
-+		reason = BFQ_BFQQ_TOO_IDLE;
-+	else
-+		goto schedule_dispatch;
-+
-+	bfq_bfqq_expire(bfqd, bfqq, true, reason);
-+
-+schedule_dispatch:
-+	spin_unlock_irqrestore(&bfqd->lock, flags);
-+	bfq_schedule_dispatch(bfqd);
-+}
-+
-+/*
-+ * Handler of the expiration of the timer running if the in-service queue
-+ * is idling inside its time slice.
-+ */
-+static enum hrtimer_restart bfq_idle_slice_timer(struct hrtimer *timer)
-+{
-+	struct bfq_data *bfqd = container_of(timer, struct bfq_data,
-+					     idle_slice_timer);
-+	struct bfq_queue *bfqq = bfqd->in_service_queue;
-+
-+	bfq_log(bfqd, "expired");
-+
-+	/*
-+	 * Theoretical race here: the in-service queue can be NULL or
-+	 * different from the queue that was idling if a new request
-+	 * arrives for the current queue and there is a full dispatch
-+	 * cycle that changes the in-service queue.  This can hardly
-+	 * happen, but in the worst case we just expire a queue too
-+	 * early.
-+	 */
-+	if (bfqq)
-+		bfq_idle_slice_timer_body(bfqq);
-+
-+	return HRTIMER_NORESTART;
-+}
-+
-+static void __bfq_put_async_bfqq(struct bfq_data *bfqd,
-+				 struct bfq_queue **bfqq_ptr)
-+{
-+	struct bfq_group *root_group = bfqd->root_group;
-+	struct bfq_queue *bfqq = *bfqq_ptr;
-+
-+	bfq_log(bfqd, "%p", bfqq);
-+	if (bfqq) {
-+		bfq_bfqq_move(bfqd, bfqq, root_group);
-+		bfq_log_bfqq(bfqd, bfqq, "putting %p, %d",
-+			     bfqq, bfqq->ref);
-+		bfq_put_queue(bfqq);
-+		*bfqq_ptr = NULL;
-+	}
-+}
-+
-+/*
-+ * Release all the bfqg references to its async queues.  If we are
-+ * deallocating the group these queues may still contain requests, so
-+ * we reparent them to the root cgroup (i.e., the only one that will
-+ * exist for sure until all the requests on a device are gone).
-+ */
-+static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg)
-+{
-+	int i, j;
-+
-+	for (i = 0; i < 2; i++)
-+		for (j = 0; j < IOPRIO_BE_NR; j++)
-+			__bfq_put_async_bfqq(bfqd, &bfqg->async_bfqq[i][j]);
-+
-+	__bfq_put_async_bfqq(bfqd, &bfqg->async_idle_bfqq);
-+}
-+
-+/*
-+ * See the comments on bfq_limit_depth for the purpose of
-+ * the depths set in the function. Return minimum shallow depth we'll use.
-+ */
-+static unsigned int bfq_update_depths(struct bfq_data *bfqd,
-+				      struct sbitmap_queue *bt)
-+{
-+	unsigned int i, j, min_shallow = UINT_MAX;
-+
-+	/*
-+	 * In-word depths if no bfq_queue is being weight-raised:
-+	 * leaving 25% of tags only for sync reads.
-+	 *
-+	 * In next formulas, right-shift the value
-+	 * (1U<<bt->sb.shift), instead of computing directly
-+	 * (1U<<(bt->sb.shift - something)), to be robust against
-+	 * any possible value of bt->sb.shift, without having to
-+	 * limit 'something'.
-+	 */
-+	/* no more than 50% of tags for async I/O */
-+	bfqd->word_depths[0][0] = max((1U<<bt->sb.shift)>>1, 1U);
-+	/*
-+	 * no more than 75% of tags for sync writes (25% extra tags
-+	 * w.r.t. async I/O, to prevent async I/O from starving sync
-+	 * writes)
-+	 */
-+	bfqd->word_depths[0][1] = max(((1U<<bt->sb.shift) * 3)>>2, 1U);
-+
-+	/*
-+	 * In-word depths in case some bfq_queue is being weight-
-+	 * raised: leaving ~63% of tags for sync reads. This is the
-+	 * highest percentage for which, in our tests, application
-+	 * start-up times didn't suffer from any regression due to tag
-+	 * shortage.
-+	 */
-+	/* no more than ~18% of tags for async I/O */
-+	bfqd->word_depths[1][0] = max(((1U<<bt->sb.shift) * 3)>>4, 1U);
-+	/* no more than ~37% of tags for sync writes (~20% extra tags) */
-+	bfqd->word_depths[1][1] = max(((1U<<bt->sb.shift) * 6)>>4, 1U);
-+
-+	for (i = 0; i < 2; i++)
-+		for (j = 0; j < 2; j++)
-+			min_shallow = min(min_shallow, bfqd->word_depths[i][j]);
-+
-+	return min_shallow;
-+}
-+
-+static void bfq_depth_updated(struct blk_mq_hw_ctx *hctx)
-+{
-+	struct bfq_data *bfqd = hctx->queue->elevator->elevator_data;
-+	struct blk_mq_tags *tags = hctx->sched_tags;
-+	unsigned int min_shallow;
-+
-+	min_shallow = bfq_update_depths(bfqd, &tags->bitmap_tags);
-+	sbitmap_queue_min_shallow_depth(&tags->bitmap_tags, min_shallow);
-+}
-+
-+static int bfq_init_hctx(struct blk_mq_hw_ctx *hctx, unsigned int index)
-+{
-+	bfq_depth_updated(hctx);
-+	return 0;
-+}
-+
-+static void bfq_exit_queue(struct elevator_queue *e)
-+{
-+	struct bfq_data *bfqd = e->elevator_data;
-+	struct bfq_queue *bfqq, *n;
-+
-+	bfq_log(bfqd, "starting ...");
-+
-+	hrtimer_cancel(&bfqd->idle_slice_timer);
-+
-+	BUG_ON(bfqd->in_service_queue);
-+	BUG_ON(!list_empty(&bfqd->active_list));
-+
-+	spin_lock_irq(&bfqd->lock);
-+	list_for_each_entry_safe(bfqq, n, &bfqd->idle_list, bfqq_list)
-+		bfq_deactivate_bfqq(bfqd, bfqq, false, false);
-+	spin_unlock_irq(&bfqd->lock);
-+
-+	hrtimer_cancel(&bfqd->idle_slice_timer);
-+
-+	BUG_ON(hrtimer_active(&bfqd->idle_slice_timer));
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	/* release oom-queue reference to root group */
-+	bfqg_and_blkg_put(bfqd->root_group);
-+
-+	blkcg_deactivate_policy(bfqd->queue, &blkcg_policy_bfq);
-+#else
-+	spin_lock_irq(&bfqd->lock);
-+	bfq_put_async_queues(bfqd, bfqd->root_group);
-+	kfree(bfqd->root_group);
-+	spin_unlock_irq(&bfqd->lock);
-+#endif
-+
-+	bfq_log(bfqd, "finished ...");
-+	kfree(bfqd);
-+}
-+
-+static void bfq_init_root_group(struct bfq_group *root_group,
-+				struct bfq_data *bfqd)
-+{
-+	int i;
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	root_group->entity.parent = NULL;
-+	root_group->my_entity = NULL;
-+	root_group->bfqd = bfqd;
-+#endif
-+	root_group->rq_pos_tree = RB_ROOT;
-+	for (i = 0; i < BFQ_IOPRIO_CLASSES; i++)
-+		root_group->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT;
-+	root_group->sched_data.bfq_class_idle_last_service = jiffies;
-+}
-+
-+static int bfq_init_queue(struct request_queue *q, struct elevator_type *e)
-+{
-+	struct bfq_data *bfqd;
-+	struct elevator_queue *eq;
-+
-+	eq = elevator_alloc(q, e);
-+	if (!eq)
-+		return -ENOMEM;
-+
-+	bfqd = kzalloc_node(sizeof(*bfqd), GFP_KERNEL, q->node);
-+	if (!bfqd) {
-+		kobject_put(&eq->kobj);
-+		return -ENOMEM;
-+	}
-+	eq->elevator_data = bfqd;
-+
-+	spin_lock_irq(q->queue_lock);
-+	q->elevator = eq;
-+	spin_unlock_irq(q->queue_lock);
-+
-+	/*
-+	 * Our fallback bfqq if bfq_find_alloc_queue() runs into OOM issues.
-+	 * Grab a permanent reference to it, so that the normal code flow
-+	 * will not attempt to free it.
-+	 */
-+	bfq_init_bfqq(bfqd, &bfqd->oom_bfqq, NULL, 1, 0);
-+	bfqd->oom_bfqq.ref++;
-+	bfqd->oom_bfqq.new_ioprio = BFQ_DEFAULT_QUEUE_IOPRIO;
-+	bfqd->oom_bfqq.new_ioprio_class = IOPRIO_CLASS_BE;
-+	bfqd->oom_bfqq.entity.new_weight =
-+		bfq_ioprio_to_weight(bfqd->oom_bfqq.new_ioprio);
-+
-+	/* oom_bfqq does not participate to bursts */
-+	bfq_clear_bfqq_just_created(&bfqd->oom_bfqq);
-+	/*
-+	 * Trigger weight initialization, according to ioprio, at the
-+	 * oom_bfqq's first activation. The oom_bfqq's ioprio and ioprio
-+	 * class won't be changed any more.
-+	 */
-+	bfqd->oom_bfqq.entity.prio_changed = 1;
-+
-+	bfqd->queue = q;
-+	INIT_LIST_HEAD(&bfqd->dispatch);
-+
-+	hrtimer_init(&bfqd->idle_slice_timer, CLOCK_MONOTONIC,
-+		     HRTIMER_MODE_REL);
-+	bfqd->idle_slice_timer.function = bfq_idle_slice_timer;
-+
-+	bfqd->queue_weights_tree = RB_ROOT;
-+	bfqd->num_groups_with_pending_reqs = 0;
-+
-+	INIT_LIST_HEAD(&bfqd->active_list);
-+	INIT_LIST_HEAD(&bfqd->idle_list);
-+	INIT_HLIST_HEAD(&bfqd->burst_list);
-+
-+	bfqd->hw_tag = -1;
-+
-+	bfqd->bfq_max_budget = bfq_default_max_budget;
-+
-+	bfqd->bfq_fifo_expire[0] = bfq_fifo_expire[0];
-+	bfqd->bfq_fifo_expire[1] = bfq_fifo_expire[1];
-+	bfqd->bfq_back_max = bfq_back_max;
-+	bfqd->bfq_back_penalty = bfq_back_penalty;
-+	bfqd->bfq_slice_idle = bfq_slice_idle;
-+	bfqd->bfq_timeout = bfq_timeout;
-+
-+	bfqd->bfq_requests_within_timer = 120;
-+
-+	bfqd->bfq_large_burst_thresh = 8;
-+	bfqd->bfq_burst_interval = msecs_to_jiffies(180);
-+
-+	bfqd->low_latency = true;
-+
-+	/*
-+	 * Trade-off between responsiveness and fairness.
-+	 */
-+	bfqd->bfq_wr_coeff = 30;
-+	bfqd->bfq_wr_rt_max_time = msecs_to_jiffies(300);
-+	bfqd->bfq_wr_max_time = 0;
-+	bfqd->bfq_wr_min_idle_time = msecs_to_jiffies(2000);
-+	bfqd->bfq_wr_min_inter_arr_async = msecs_to_jiffies(500);
-+	bfqd->bfq_wr_max_softrt_rate = 7000; /*
-+					      * Approximate rate required
-+					      * to playback or record a
-+					      * high-definition compressed
-+					      * video.
-+					      */
-+	bfqd->wr_busy_queues = 0;
-+
-+	/*
-+	 * Begin by assuming, optimistically, that the device peak
-+	 * rate is equal to 2/3 of the highest reference rate.
-+	 */
-+	bfqd->rate_dur_prod = ref_rate[blk_queue_nonrot(bfqd->queue)] *
-+		ref_wr_duration[blk_queue_nonrot(bfqd->queue)];
-+	bfqd->peak_rate = ref_rate[blk_queue_nonrot(bfqd->queue)] * 2 / 3;
-+
-+	spin_lock_init(&bfqd->lock);
-+
-+	/*
-+	 * The invocation of the next bfq_create_group_hierarchy
-+	 * function is the head of a chain of function calls
-+	 * (bfq_create_group_hierarchy->blkcg_activate_policy->
-+	 * blk_mq_freeze_queue) that may lead to the invocation of the
-+	 * has_work hook function. For this reason,
-+	 * bfq_create_group_hierarchy is invoked only after all
-+	 * scheduler data has been initialized, apart from the fields
-+	 * that can be initialized only after invoking
-+	 * bfq_create_group_hierarchy. This, in particular, enables
-+	 * has_work to correctly return false. Of course, to avoid
-+	 * other inconsistencies, the blk-mq stack must then refrain
-+	 * from invoking further scheduler hooks before this init
-+	 * function is finished.
-+	*/
-+	bfqd->root_group = bfq_create_group_hierarchy(bfqd, q->node);
-+	if (!bfqd->root_group)
-+		goto out_free;
-+	bfq_init_root_group(bfqd->root_group, bfqd);
-+	bfq_init_entity(&bfqd->oom_bfqq.entity, bfqd->root_group);
-+
-+	wbt_disable_default(q);
-+	return 0;
-+
-+out_free:
-+	kfree(bfqd);
-+	kobject_put(&eq->kobj);
-+	return -ENOMEM;
-+}
-+
-+static void bfq_slab_kill(void)
-+{
-+	kmem_cache_destroy(bfq_pool);
-+}
-+
-+static int __init bfq_slab_setup(void)
-+{
-+	bfq_pool = KMEM_CACHE(bfq_queue, 0);
-+	if (!bfq_pool)
-+		return -ENOMEM;
-+	return 0;
-+}
-+
-+static ssize_t bfq_var_show(unsigned int var, char *page)
-+{
-+	return sprintf(page, "%u\n", var);
-+}
-+
-+static ssize_t bfq_var_store(unsigned long *var, const char *page,
-+			     size_t count)
-+{
-+	unsigned long new_val;
-+	int ret = kstrtoul(page, 10, &new_val);
-+
-+	if (ret == 0)
-+		*var = new_val;
-+
-+	return count;
-+}
-+
-+static ssize_t bfq_wr_max_time_show(struct elevator_queue *e, char *page)
-+{
-+	struct bfq_data *bfqd = e->elevator_data;
-+
-+	return sprintf(page, "%d\n", bfqd->bfq_wr_max_time > 0 ?
-+		       jiffies_to_msecs(bfqd->bfq_wr_max_time) :
-+		       jiffies_to_msecs(bfq_wr_duration(bfqd)));
-+}
-+
-+static ssize_t bfq_weights_show(struct elevator_queue *e, char *page)
-+{
-+	struct bfq_queue *bfqq;
-+	struct bfq_data *bfqd = e->elevator_data;
-+	ssize_t num_char = 0;
-+
-+	num_char += sprintf(page + num_char, "Tot reqs queued %d\n\n",
-+			    bfqd->queued);
-+
-+	spin_lock_irq(&bfqd->lock);
-+
-+	num_char += sprintf(page + num_char, "Active:\n");
-+	list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list) {
-+		num_char += sprintf(page + num_char,
-+				    "pid%d: weight %hu, nr_queued %d %d, ",
-+				    bfqq->pid,
-+				    bfqq->entity.weight,
-+				    bfqq->queued[0],
-+				    bfqq->queued[1]);
-+		num_char += sprintf(page + num_char,
-+				    "dur %d/%u\n",
-+				    jiffies_to_msecs(
-+					    jiffies -
-+					    bfqq->last_wr_start_finish),
-+				    jiffies_to_msecs(bfqq->wr_cur_max_time));
-+	}
-+
-+	num_char += sprintf(page + num_char, "Idle:\n");
-+	list_for_each_entry(bfqq, &bfqd->idle_list, bfqq_list) {
-+		num_char += sprintf(page + num_char,
-+				    "pid%d: weight %hu, dur %d/%u\n",
-+				    bfqq->pid,
-+				    bfqq->entity.weight,
-+				    jiffies_to_msecs(jiffies -
-+						     bfqq->last_wr_start_finish),
-+				    jiffies_to_msecs(bfqq->wr_cur_max_time));
-+	}
-+
-+	spin_unlock_irq(&bfqd->lock);
-+
-+	return num_char;
-+}
-+
-+#define SHOW_FUNCTION(__FUNC, __VAR, __CONV)				\
-+static ssize_t __FUNC(struct elevator_queue *e, char *page)		\
-+{									\
-+	struct bfq_data *bfqd = e->elevator_data;			\
-+	u64 __data = __VAR;						\
-+	if (__CONV == 1)						\
-+		__data = jiffies_to_msecs(__data);			\
-+	else if (__CONV == 2)						\
-+		__data = div_u64(__data, NSEC_PER_MSEC);		\
-+	return bfq_var_show(__data, (page));				\
-+}
-+SHOW_FUNCTION(bfq_fifo_expire_sync_show, bfqd->bfq_fifo_expire[1], 2);
-+SHOW_FUNCTION(bfq_fifo_expire_async_show, bfqd->bfq_fifo_expire[0], 2);
-+SHOW_FUNCTION(bfq_back_seek_max_show, bfqd->bfq_back_max, 0);
-+SHOW_FUNCTION(bfq_back_seek_penalty_show, bfqd->bfq_back_penalty, 0);
-+SHOW_FUNCTION(bfq_slice_idle_show, bfqd->bfq_slice_idle, 2);
-+SHOW_FUNCTION(bfq_max_budget_show, bfqd->bfq_user_max_budget, 0);
-+SHOW_FUNCTION(bfq_timeout_sync_show, bfqd->bfq_timeout, 1);
-+SHOW_FUNCTION(bfq_strict_guarantees_show, bfqd->strict_guarantees, 0);
-+SHOW_FUNCTION(bfq_low_latency_show, bfqd->low_latency, 0);
-+SHOW_FUNCTION(bfq_wr_coeff_show, bfqd->bfq_wr_coeff, 0);
-+SHOW_FUNCTION(bfq_wr_rt_max_time_show, bfqd->bfq_wr_rt_max_time, 1);
-+SHOW_FUNCTION(bfq_wr_min_idle_time_show, bfqd->bfq_wr_min_idle_time, 1);
-+SHOW_FUNCTION(bfq_wr_min_inter_arr_async_show, bfqd->bfq_wr_min_inter_arr_async,
-+	1);
-+SHOW_FUNCTION(bfq_wr_max_softrt_rate_show, bfqd->bfq_wr_max_softrt_rate, 0);
-+#undef SHOW_FUNCTION
-+
-+#define USEC_SHOW_FUNCTION(__FUNC, __VAR)				\
-+static ssize_t __FUNC(struct elevator_queue *e, char *page)		\
-+{									\
-+	struct bfq_data *bfqd = e->elevator_data;			\
-+	u64 __data = __VAR;						\
-+	__data = div_u64(__data, NSEC_PER_USEC);			\
-+	return bfq_var_show(__data, (page));				\
-+}
-+USEC_SHOW_FUNCTION(bfq_slice_idle_us_show, bfqd->bfq_slice_idle);
-+#undef USEC_SHOW_FUNCTION
-+
-+#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV)			\
-+static ssize_t								\
-+__FUNC(struct elevator_queue *e, const char *page, size_t count)	\
-+{									\
-+	struct bfq_data *bfqd = e->elevator_data;			\
-+	unsigned long uninitialized_var(__data);			\
-+	int ret = bfq_var_store(&__data, (page), count);		\
-+	if (__data < (MIN))						\
-+		__data = (MIN);						\
-+	else if (__data > (MAX))					\
-+		__data = (MAX);						\
-+	if (__CONV == 1)						\
-+		*(__PTR) = msecs_to_jiffies(__data);			\
-+	else if (__CONV == 2)						\
-+		*(__PTR) = (u64)__data * NSEC_PER_MSEC;			\
-+	else								\
-+		*(__PTR) = __data;					\
-+	return ret;							\
-+}
-+STORE_FUNCTION(bfq_fifo_expire_sync_store, &bfqd->bfq_fifo_expire[1], 1,
-+		INT_MAX, 2);
-+STORE_FUNCTION(bfq_fifo_expire_async_store, &bfqd->bfq_fifo_expire[0], 1,
-+		INT_MAX, 2);
-+STORE_FUNCTION(bfq_back_seek_max_store, &bfqd->bfq_back_max, 0, INT_MAX, 0);
-+STORE_FUNCTION(bfq_back_seek_penalty_store, &bfqd->bfq_back_penalty, 1,
-+		INT_MAX, 0);
-+STORE_FUNCTION(bfq_slice_idle_store, &bfqd->bfq_slice_idle, 0, INT_MAX, 2);
-+STORE_FUNCTION(bfq_wr_coeff_store, &bfqd->bfq_wr_coeff, 1, INT_MAX, 0);
-+STORE_FUNCTION(bfq_wr_max_time_store, &bfqd->bfq_wr_max_time, 0, INT_MAX, 1);
-+STORE_FUNCTION(bfq_wr_rt_max_time_store, &bfqd->bfq_wr_rt_max_time, 0, INT_MAX,
-+		1);
-+STORE_FUNCTION(bfq_wr_min_idle_time_store, &bfqd->bfq_wr_min_idle_time, 0,
-+		INT_MAX, 1);
-+STORE_FUNCTION(bfq_wr_min_inter_arr_async_store,
-+		&bfqd->bfq_wr_min_inter_arr_async, 0, INT_MAX, 1);
-+STORE_FUNCTION(bfq_wr_max_softrt_rate_store, &bfqd->bfq_wr_max_softrt_rate, 0,
-+		INT_MAX, 0);
-+#undef STORE_FUNCTION
-+
-+#define USEC_STORE_FUNCTION(__FUNC, __PTR, MIN, MAX)			\
-+static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count)\
-+{									\
-+	struct bfq_data *bfqd = e->elevator_data;			\
-+	unsigned long uninitialized_var(__data);			\
-+	int ret = bfq_var_store(&__data, (page), count);		\
-+	if (__data < (MIN))						\
-+		__data = (MIN);						\
-+	else if (__data > (MAX))					\
-+		__data = (MAX);						\
-+	*(__PTR) = (u64)__data * NSEC_PER_USEC;				\
-+	return ret;							\
-+}
-+USEC_STORE_FUNCTION(bfq_slice_idle_us_store, &bfqd->bfq_slice_idle, 0,
-+		    UINT_MAX);
-+#undef USEC_STORE_FUNCTION
-+
-+/* do nothing for the moment */
-+static ssize_t bfq_weights_store(struct elevator_queue *e,
-+				    const char *page, size_t count)
-+{
-+	return count;
-+}
-+
-+static ssize_t bfq_max_budget_store(struct elevator_queue *e,
-+				    const char *page, size_t count)
-+{
-+	struct bfq_data *bfqd = e->elevator_data;
-+	unsigned long uninitialized_var(__data);
-+	int ret = bfq_var_store(&__data, (page), count);
-+
-+	if (__data == 0)
-+		bfqd->bfq_max_budget = bfq_calc_max_budget(bfqd);
-+	else {
-+		if (__data > INT_MAX)
-+			__data = INT_MAX;
-+		bfqd->bfq_max_budget = __data;
-+	}
-+
-+	bfqd->bfq_user_max_budget = __data;
-+
-+	return ret;
-+}
-+
-+/*
-+ * Leaving this name to preserve name compatibility with cfq
-+ * parameters, but this timeout is used for both sync and async.
-+ */
-+static ssize_t bfq_timeout_sync_store(struct elevator_queue *e,
-+				      const char *page, size_t count)
-+{
-+	struct bfq_data *bfqd = e->elevator_data;
-+	unsigned long uninitialized_var(__data);
-+	int ret = bfq_var_store(&__data, (page), count);
-+
-+	if (__data < 1)
-+		__data = 1;
-+	else if (__data > INT_MAX)
-+		__data = INT_MAX;
-+
-+	bfqd->bfq_timeout = msecs_to_jiffies(__data);
-+	if (bfqd->bfq_user_max_budget == 0)
-+		bfqd->bfq_max_budget = bfq_calc_max_budget(bfqd);
-+
-+	return ret;
-+}
-+
-+static ssize_t bfq_strict_guarantees_store(struct elevator_queue *e,
-+				     const char *page, size_t count)
-+{
-+	struct bfq_data *bfqd = e->elevator_data;
-+	unsigned long uninitialized_var(__data);
-+	int ret = bfq_var_store(&__data, (page), count);
-+
-+	if (__data > 1)
-+		__data = 1;
-+	if (!bfqd->strict_guarantees && __data == 1
-+	    && bfqd->bfq_slice_idle < 8 * NSEC_PER_MSEC)
-+		bfqd->bfq_slice_idle = 8 * NSEC_PER_MSEC;
-+
-+	bfqd->strict_guarantees = __data;
-+
-+	return ret;
-+}
-+
-+static ssize_t bfq_low_latency_store(struct elevator_queue *e,
-+				     const char *page, size_t count)
-+{
-+	struct bfq_data *bfqd = e->elevator_data;
-+	unsigned long uninitialized_var(__data);
-+	int ret = bfq_var_store(&__data, (page), count);
-+
-+	if (__data > 1)
-+		__data = 1;
-+	if (__data == 0 && bfqd->low_latency != 0)
-+		bfq_end_wr(bfqd);
-+	bfqd->low_latency = __data;
-+
-+	return ret;
-+}
-+
-+#define BFQ_ATTR(name) \
-+	__ATTR(name, S_IRUGO|S_IWUSR, bfq_##name##_show, bfq_##name##_store)
-+
-+static struct elv_fs_entry bfq_attrs[] = {
-+	BFQ_ATTR(fifo_expire_sync),
-+	BFQ_ATTR(fifo_expire_async),
-+	BFQ_ATTR(back_seek_max),
-+	BFQ_ATTR(back_seek_penalty),
-+	BFQ_ATTR(slice_idle),
-+	BFQ_ATTR(slice_idle_us),
-+	BFQ_ATTR(max_budget),
-+	BFQ_ATTR(timeout_sync),
-+	BFQ_ATTR(strict_guarantees),
-+	BFQ_ATTR(low_latency),
-+	BFQ_ATTR(wr_coeff),
-+	BFQ_ATTR(wr_max_time),
-+	BFQ_ATTR(wr_rt_max_time),
-+	BFQ_ATTR(wr_min_idle_time),
-+	BFQ_ATTR(wr_min_inter_arr_async),
-+	BFQ_ATTR(wr_max_softrt_rate),
-+	BFQ_ATTR(weights),
-+	__ATTR_NULL
-+};
-+
-+static struct elevator_type iosched_bfq_mq = {
-+	.ops.mq = {
-+		.limit_depth		= bfq_limit_depth,
-+		.prepare_request        = bfq_prepare_request,
-+		.requeue_request	= bfq_finish_requeue_request,
-+		.finish_request         = bfq_finish_requeue_request,
-+		.exit_icq		= bfq_exit_icq,
-+		.insert_requests	= bfq_insert_requests,
-+		.dispatch_request	= bfq_dispatch_request,
-+		.next_request		= elv_rb_latter_request,
-+		.former_request		= elv_rb_former_request,
-+		.allow_merge		= bfq_allow_bio_merge,
-+		.bio_merge		= bfq_bio_merge,
-+		.request_merge		= bfq_request_merge,
-+		.requests_merged	= bfq_requests_merged,
-+		.request_merged		= bfq_request_merged,
-+		.has_work		= bfq_has_work,
-+		.depth_updated		= bfq_depth_updated,
-+		.init_hctx              = bfq_init_hctx,
-+		.init_sched		= bfq_init_queue,
-+		.exit_sched		= bfq_exit_queue,
-+	},
-+
-+	.uses_mq =		true,
-+	.icq_size =		sizeof(struct bfq_io_cq),
-+	.icq_align =		__alignof__(struct bfq_io_cq),
-+	.elevator_attrs =	bfq_attrs,
-+	.elevator_name =	"bfq-mq",
-+	.elevator_owner =	THIS_MODULE,
-+};
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+static struct blkcg_policy blkcg_policy_bfq = {
-+	.dfl_cftypes		= bfq_blkg_files,
-+	.legacy_cftypes		= bfq_blkcg_legacy_files,
-+
-+	.cpd_alloc_fn		= bfq_cpd_alloc,
-+	.cpd_init_fn		= bfq_cpd_init,
-+	.cpd_bind_fn	        = bfq_cpd_init,
-+	.cpd_free_fn		= bfq_cpd_free,
-+
-+	.pd_alloc_fn		= bfq_pd_alloc,
-+	.pd_init_fn		= bfq_pd_init,
-+	.pd_offline_fn		= bfq_pd_offline,
-+	.pd_free_fn		= bfq_pd_free,
-+	.pd_reset_stats_fn	= bfq_pd_reset_stats,
-+};
-+#endif
-+
-+static int __init bfq_init(void)
-+{
-+	int ret;
-+	char msg[60] = "BFQ I/O-scheduler: v9";
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	ret = blkcg_policy_register(&blkcg_policy_bfq);
-+	if (ret)
-+		return ret;
-+#endif
-+
-+	ret = -ENOMEM;
-+	if (bfq_slab_setup())
-+		goto err_pol_unreg;
-+
-+	/*
-+	 * Times to load large popular applications for the typical
-+	 * systems installed on the reference devices (see the
-+	 * comments before the definition of the next
-+	 * array). Actually, we use slightly lower values, as the
-+	 * estimated peak rate tends to be smaller than the actual
-+	 * peak rate.  The reason for this last fact is that estimates
-+	 * are computed over much shorter time intervals than the long
-+	 * intervals typically used for benchmarking. Why? First, to
-+	 * adapt more quickly to variations. Second, because an I/O
-+	 * scheduler cannot rely on a peak-rate-evaluation workload to
-+	 * be run for a long time.
-+	 */
-+	ref_wr_duration[0] = msecs_to_jiffies(7000); /* actually 8 sec */
-+	ref_wr_duration[1] = msecs_to_jiffies(2500); /* actually 3 sec */
-+
-+	ret = elv_register(&iosched_bfq_mq);
-+	if (ret)
-+		goto slab_kill;
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	strcat(msg, " (with cgroups support)");
-+#endif
-+	pr_info("%s", msg);
-+
-+	return 0;
-+
-+slab_kill:
-+	bfq_slab_kill();
-+err_pol_unreg:
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	blkcg_policy_unregister(&blkcg_policy_bfq);
-+#endif
-+	return ret;
-+}
-+
-+static void __exit bfq_exit(void)
-+{
-+	elv_unregister(&iosched_bfq_mq);
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	blkcg_policy_unregister(&blkcg_policy_bfq);
-+#endif
-+	bfq_slab_kill();
-+}
-+
-+module_init(bfq_init);
-+module_exit(bfq_exit);
-+
-+MODULE_AUTHOR("Paolo Valente");
-+MODULE_LICENSE("GPL");
-+MODULE_DESCRIPTION("MQ Budget Fair Queueing I/O Scheduler");
-diff --git a/block/bfq-mq.h b/block/bfq-mq.h
-new file mode 100644
-index 000000000000..ceb291132a1a
---- /dev/null
-+++ b/block/bfq-mq.h
-@@ -0,0 +1,1077 @@
-+/*
-+ * BFQ v9: data structures and common functions prototypes.
-+ *
-+ * Based on ideas and code from CFQ:
-+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
-+ *
-+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
-+ *		      Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2017 Paolo Valente <paolo.valente@linaro.org>
-+ */
-+
-+#ifndef _BFQ_H
-+#define _BFQ_H
-+
-+#include <linux/hrtimer.h>
-+#include <linux/blk-cgroup.h>
-+
-+/* see comments on CONFIG_BFQ_GROUP_IOSCHED in bfq.h */
-+#ifdef CONFIG_MQ_BFQ_GROUP_IOSCHED
-+#define BFQ_GROUP_IOSCHED_ENABLED
-+#endif
-+
-+#define BFQ_IOPRIO_CLASSES	3
-+#define BFQ_CL_IDLE_TIMEOUT	(HZ/5)
-+
-+#define BFQ_MIN_WEIGHT			1
-+#define BFQ_MAX_WEIGHT			1000
-+#define BFQ_WEIGHT_CONVERSION_COEFF	10
-+
-+#define BFQ_DEFAULT_QUEUE_IOPRIO	4
-+
-+#define BFQ_WEIGHT_LEGACY_DFL	100
-+#define BFQ_DEFAULT_GRP_IOPRIO	0
-+#define BFQ_DEFAULT_GRP_CLASS	IOPRIO_CLASS_BE
-+
-+/*
-+ * Soft real-time applications are extremely more latency sensitive
-+ * than interactive ones. Over-raise the weight of the former to
-+ * privilege them against the latter.
-+ */
-+#define BFQ_SOFTRT_WEIGHT_FACTOR	100
-+
-+struct bfq_entity;
-+
-+/**
-+ * struct bfq_service_tree - per ioprio_class service tree.
-+ *
-+ * Each service tree represents a B-WF2Q+ scheduler on its own.  Each
-+ * ioprio_class has its own independent scheduler, and so its own
-+ * bfq_service_tree.  All the fields are protected by the queue lock
-+ * of the containing bfqd.
-+ */
-+struct bfq_service_tree {
-+	/* tree for active entities (i.e., those backlogged) */
-+	struct rb_root active;
-+	/* tree for idle entities (i.e., not backlogged, with V <= F_i)*/
-+	struct rb_root idle;
-+
-+	struct bfq_entity *first_idle;	/* idle entity with minimum F_i */
-+	struct bfq_entity *last_idle;	/* idle entity with maximum F_i */
-+
-+	u64 vtime; /* scheduler virtual time */
-+	/* scheduler weight sum; active and idle entities contribute to it */
-+	unsigned long wsum;
-+};
-+
-+/**
-+ * struct bfq_sched_data - multi-class scheduler.
-+ *
-+ * bfq_sched_data is the basic scheduler queue.  It supports three
-+ * ioprio_classes, and can be used either as a toplevel queue or as an
-+ * intermediate queue in a hierarchical setup.
-+ *
-+ * The supported ioprio_classes are the same as in CFQ, in descending
-+ * priority order, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE.
-+ * Requests from higher priority queues are served before all the
-+ * requests from lower priority queues; among requests of the same
-+ * queue requests are served according to B-WF2Q+.
-+ *
-+ * The schedule is implemented by the service trees, plus the field
-+ * @next_in_service, which points to the entity on the active trees
-+ * that will be served next, if 1) no changes in the schedule occurs
-+ * before the current in-service entity is expired, 2) the in-service
-+ * queue becomes idle when it expires, and 3) if the entity pointed by
-+ * in_service_entity is not a queue, then the in-service child entity
-+ * of the entity pointed by in_service_entity becomes idle on
-+ * expiration. This peculiar definition allows for the following
-+ * optimization, not yet exploited: while a given entity is still in
-+ * service, we already know which is the best candidate for next
-+ * service among the other active entitities in the same parent
-+ * entity. We can then quickly compare the timestamps of the
-+ * in-service entity with those of such best candidate.
-+ *
-+ * All the fields are protected by the queue lock of the containing
-+ * bfqd.
-+ */
-+struct bfq_sched_data {
-+	struct bfq_entity *in_service_entity;  /* entity in service */
-+	/* head-of-the-line entity in the scheduler (see comments above) */
-+	struct bfq_entity *next_in_service;
-+	/* array of service trees, one per ioprio_class */
-+	struct bfq_service_tree service_tree[BFQ_IOPRIO_CLASSES];
-+	/* last time CLASS_IDLE was served */
-+	unsigned long bfq_class_idle_last_service;
-+
-+};
-+
-+/**
-+ * struct bfq_weight_counter - counter of the number of all active queues
-+ *                             with a given weight.
-+ */
-+struct bfq_weight_counter {
-+	unsigned int weight; /* weight of the queues this counter refers to */
-+	unsigned int num_active; /* nr of active queues with this weight */
-+	/*
-+	 * Weights tree member (see bfq_data's @queue_weights_tree)
-+	 */
-+	struct rb_node weights_node;
-+};
-+
-+/**
-+ * struct bfq_entity - schedulable entity.
-+ *
-+ * A bfq_entity is used to represent either a bfq_queue (leaf node in the
-+ * cgroup hierarchy) or a bfq_group into the upper level scheduler.  Each
-+ * entity belongs to the sched_data of the parent group in the cgroup
-+ * hierarchy.  Non-leaf entities have also their own sched_data, stored
-+ * in @my_sched_data.
-+ *
-+ * Each entity stores independently its priority values; this would
-+ * allow different weights on different devices, but this
-+ * functionality is not exported to userspace by now.  Priorities and
-+ * weights are updated lazily, first storing the new values into the
-+ * new_* fields, then setting the @prio_changed flag.  As soon as
-+ * there is a transition in the entity state that allows the priority
-+ * update to take place the effective and the requested priority
-+ * values are synchronized.
-+ *
-+ * Unless cgroups are used, the weight value is calculated from the
-+ * ioprio to export the same interface as CFQ.  When dealing with
-+ * ``well-behaved'' queues (i.e., queues that do not spend too much
-+ * time to consume their budget and have true sequential behavior, and
-+ * when there are no external factors breaking anticipation) the
-+ * relative weights at each level of the cgroups hierarchy should be
-+ * guaranteed.  All the fields are protected by the queue lock of the
-+ * containing bfqd.
-+ */
-+struct bfq_entity {
-+	struct rb_node rb_node; /* service_tree member */
-+
-+	/*
-+	 * Flag, true if the entity is on a tree (either the active or
-+	 * the idle one of its service_tree) or is in service.
-+	 */
-+	bool on_st;
-+
-+	u64 finish; /* B-WF2Q+ finish timestamp (aka F_i) */
-+	u64 start;  /* B-WF2Q+ start timestamp (aka S_i) */
-+
-+	/* tree the entity is enqueued into; %NULL if not on a tree */
-+	struct rb_root *tree;
-+
-+	/*
-+	 * minimum start time of the (active) subtree rooted at this
-+	 * entity; used for O(log N) lookups into active trees
-+	 */
-+	u64 min_start;
-+
-+	/* amount of service received during the last service slot */
-+	int service;
-+
-+	/* budget, used also to calculate F_i: F_i = S_i + @budget / @weight */
-+	int budget;
-+
-+	unsigned int weight;	 /* weight of the queue */
-+	unsigned int new_weight; /* next weight if a change is in progress */
-+
-+	/* original weight, used to implement weight boosting */
-+	unsigned int orig_weight;
-+
-+	/* parent entity, for hierarchical scheduling */
-+	struct bfq_entity *parent;
-+
-+	/*
-+	 * For non-leaf nodes in the hierarchy, the associated
-+	 * scheduler queue, %NULL on leaf nodes.
-+	 */
-+	struct bfq_sched_data *my_sched_data;
-+	/* the scheduler queue this entity belongs to */
-+	struct bfq_sched_data *sched_data;
-+
-+	/* flag, set to request a weight, ioprio or ioprio_class change  */
-+	int prio_changed;
-+
-+	/* flag, set if the entity is counted in groups_with_pending_reqs */
-+	bool in_groups_with_pending_reqs;
-+};
-+
-+struct bfq_group;
-+
-+/**
-+ * struct bfq_ttime - per process thinktime stats.
-+ */
-+struct bfq_ttime {
-+	u64 last_end_request; /* completion time of last request */
-+
-+	u64 ttime_total; /* total process thinktime */
-+	unsigned long ttime_samples; /* number of thinktime samples */
-+	u64 ttime_mean; /* average process thinktime */
-+
-+};
-+
-+/**
-+ * struct bfq_queue - leaf schedulable entity.
-+ *
-+ * A bfq_queue is a leaf request queue; it can be associated with an
-+ * io_context or more, if it  is  async or shared  between  cooperating
-+ * processes. @cgroup holds a reference to the cgroup, to be sure that it
-+ * does not disappear while a bfqq still references it (mostly to avoid
-+ * races between request issuing and task migration followed by cgroup
-+ * destruction).
-+ * All the fields are protected by the queue lock of the containing bfqd.
-+ */
-+struct bfq_queue {
-+	/* reference counter */
-+	int ref;
-+	/* parent bfq_data */
-+	struct bfq_data *bfqd;
-+
-+	/* current ioprio and ioprio class */
-+	unsigned short ioprio, ioprio_class;
-+	/* next ioprio and ioprio class if a change is in progress */
-+	unsigned short new_ioprio, new_ioprio_class;
-+
-+	/*
-+	 * Shared bfq_queue if queue is cooperating with one or more
-+	 * other queues.
-+	 */
-+	struct bfq_queue *new_bfqq;
-+	/* request-position tree member (see bfq_group's @rq_pos_tree) */
-+	struct rb_node pos_node;
-+	/* request-position tree root (see bfq_group's @rq_pos_tree) */
-+	struct rb_root *pos_root;
-+
-+	/* sorted list of pending requests */
-+	struct rb_root sort_list;
-+	/* if fifo isn't expired, next request to serve */
-+	struct request *next_rq;
-+	/* number of sync and async requests queued */
-+	int queued[2];
-+	/* number of requests currently allocated */
-+	int allocated;
-+	/* number of pending metadata requests */
-+	int meta_pending;
-+	/* fifo list of requests in sort_list */
-+	struct list_head fifo;
-+
-+	/* entity representing this queue in the scheduler */
-+	struct bfq_entity entity;
-+
-+	/* pointer to the weight counter associated with this queue */
-+	struct bfq_weight_counter *weight_counter;
-+
-+	/* maximum budget allowed from the feedback mechanism */
-+	int max_budget;
-+	/* budget expiration (in jiffies) */
-+	unsigned long budget_timeout;
-+
-+	/* number of requests on the dispatch list or inside driver */
-+	int dispatched;
-+
-+	unsigned int flags; /* status flags.*/
-+
-+	/* node for active/idle bfqq list inside parent bfqd */
-+	struct list_head bfqq_list;
-+
-+	/* associated @bfq_ttime struct */
-+	struct bfq_ttime ttime;
-+
-+	/* bit vector: a 1 for each seeky requests in history */
-+	u32 seek_history;
-+
-+	/* node for the device's burst list */
-+	struct hlist_node burst_list_node;
-+
-+	/* position of the last request enqueued */
-+	sector_t last_request_pos;
-+
-+	/* Number of consecutive pairs of request completion and
-+	 * arrival, such that the queue becomes idle after the
-+	 * completion, but the next request arrives within an idle
-+	 * time slice; used only if the queue's IO_bound flag has been
-+	 * cleared.
-+	 */
-+	unsigned int requests_within_timer;
-+
-+	/* pid of the process owning the queue, used for logging purposes */
-+	pid_t pid;
-+
-+	/*
-+	 * Pointer to the bfq_io_cq owning the bfq_queue, set to %NULL
-+	 * if the queue is shared.
-+	 */
-+	struct bfq_io_cq *bic;
-+
-+	/* current maximum weight-raising time for this queue */
-+	unsigned long wr_cur_max_time;
-+	/*
-+	 * Minimum time instant such that, only if a new request is
-+	 * enqueued after this time instant in an idle @bfq_queue with
-+	 * no outstanding requests, then the task associated with the
-+	 * queue it is deemed as soft real-time (see the comments on
-+	 * the function bfq_bfqq_softrt_next_start())
-+	 */
-+	unsigned long soft_rt_next_start;
-+	/*
-+	 * Start time of the current weight-raising period if
-+	 * the @bfq-queue is being weight-raised, otherwise
-+	 * finish time of the last weight-raising period.
-+	 */
-+	unsigned long last_wr_start_finish;
-+	/* factor by which the weight of this queue is multiplied */
-+	unsigned int wr_coeff;
-+	/*
-+	 * Time of the last transition of the @bfq_queue from idle to
-+	 * backlogged.
-+	 */
-+	unsigned long last_idle_bklogged;
-+	/*
-+	 * Cumulative service received from the @bfq_queue since the
-+	 * last transition from idle to backlogged.
-+	 */
-+	unsigned long service_from_backlogged;
-+	/*
-+	 * Cumulative service received from the @bfq_queue since its
-+	 * last transition to weight-raised state.
-+	 */
-+	unsigned long service_from_wr;
-+	/*
-+	 * Value of wr start time when switching to soft rt
-+	 */
-+	unsigned long wr_start_at_switch_to_srt;
-+
-+	unsigned long split_time; /* time of last split */
-+	unsigned long first_IO_time; /* time of first I/O for this queue */
-+
-+	/* max service rate measured so far */
-+	u32 max_service_rate;
-+	/*
-+	 * Ratio between the service received by bfqq while it is in
-+	 * service, and the cumulative service (of requests of other
-+	 * queues) that may be injected while bfqq is empty but still
-+	 * in service. To increase precision, the coefficient is
-+	 * measured in tenths of unit. Here are some example of (1)
-+	 * ratios, (2) resulting percentages of service injected
-+	 * w.r.t. to the total service dispatched while bfqq is in
-+	 * service, and (3) corresponding values of the coefficient:
-+	 * 1 (50%) -> 10
-+	 * 2 (33%) -> 20
-+	 * 10 (9%) -> 100
-+	 * 9.9 (9%) -> 99
-+	 * 1.5 (40%) -> 15
-+	 * 0.5 (66%) -> 5
-+	 * 0.1 (90%) -> 1
-+	 *
-+	 * So, if the coefficient is lower than 10, then
-+	 * injected service is more than bfqq service.
-+	 */
-+	unsigned int inject_coeff;
-+	/* amount of service injected in current service slot */
-+	unsigned int injected_service;
-+};
-+
-+/**
-+ * struct bfq_io_cq - per (request_queue, io_context) structure.
-+ */
-+struct bfq_io_cq {
-+	/* associated io_cq structure */
-+	struct io_cq icq; /* must be the first member */
-+	/* array of two process queues, the sync and the async */
-+	struct bfq_queue *bfqq[2];
-+	/* per (request_queue, blkcg) ioprio */
-+	int ioprio;
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	uint64_t blkcg_serial_nr; /* the current blkcg serial */
-+#endif
-+
-+	/*
-+	 * Snapshot of the has_short_time flag before merging; taken
-+	 * to remember its value while the queue is merged, so as to
-+	 * be able to restore it in case of split.
-+	 */
-+	bool saved_has_short_ttime;
-+	/*
-+	 * Same purpose as the previous two fields for the I/O bound
-+	 * classification of a queue.
-+	 */
-+	bool saved_IO_bound;
-+
-+	/*
-+	 * Same purpose as the previous fields for the value of the
-+	 * field keeping the queue's belonging to a large burst
-+	 */
-+	bool saved_in_large_burst;
-+	/*
-+	 * True if the queue belonged to a burst list before its merge
-+	 * with another cooperating queue.
-+	 */
-+	bool was_in_burst_list;
-+
-+	/*
-+	 * Similar to previous fields: save wr information.
-+	 */
-+	unsigned long saved_wr_coeff;
-+	unsigned long saved_last_wr_start_finish;
-+	unsigned long saved_wr_start_at_switch_to_srt;
-+	unsigned int saved_wr_cur_max_time;
-+	struct bfq_ttime saved_ttime;
-+};
-+
-+/**
-+ * struct bfq_data - per-device data structure.
-+ *
-+ * All the fields are protected by @lock.
-+ */
-+struct bfq_data {
-+	/* device request queue */
-+	struct request_queue *queue;
-+	/* dispatch queue */
-+	struct list_head dispatch;
-+
-+	/* root bfq_group for the device */
-+	struct bfq_group *root_group;
-+
-+	/*
-+	 * rbtree of weight counters of @bfq_queues, sorted by
-+	 * weight. Used to keep track of whether all @bfq_queues have
-+	 * the same weight. The tree contains one counter for each
-+	 * distinct weight associated to some active and not
-+	 * weight-raised @bfq_queue (see the comments to the functions
-+	 * bfq_weights_tree_[add|remove] for further details).
-+	 */
-+	struct rb_root queue_weights_tree;
-+
-+	/*
-+	 * Number of groups with at least one descendant process that
-+	 * has at least one request waiting for completion. Note that
-+	 * this accounts for also requests already dispatched, but not
-+	 * yet completed. Therefore this number of groups may differ
-+	 * (be larger) than the number of active groups, as a group is
-+	 * considered active only if its corresponding entity has
-+	 * descendant queues with at least one request queued. This
-+	 * number is used to decide whether a scenario is symmetric.
-+	 * For a detailed explanation see comments on the computation
-+	 * of the variable asymmetric_scenario in the function
-+	 * bfq_better_to_idle().
-+	 *
-+	 * However, it is hard to compute this number exactly, for
-+	 * groups with multiple descendant processes. Consider a group
-+	 * that is inactive, i.e., that has no descendant process with
-+	 * pending I/O inside BFQ queues. Then suppose that
-+	 * num_groups_with_pending_reqs is still accounting for this
-+	 * group, because the group has descendant processes with some
-+	 * I/O request still in flight. num_groups_with_pending_reqs
-+	 * should be decremented when the in-flight request of the
-+	 * last descendant process is finally completed (assuming that
-+	 * nothing else has changed for the group in the meantime, in
-+	 * terms of composition of the group and active/inactive state of child
-+	 * groups and processes). To accomplish this, an additional
-+	 * pending-request counter must be added to entities, and must
-+	 * be updated correctly. To avoid this additional field and operations,
-+	 * we resort to the following tradeoff between simplicity and
-+	 * accuracy: for an inactive group that is still counted in
-+	 * num_groups_with_pending_reqs, we decrement
-+	 * num_groups_with_pending_reqs when the first descendant
-+	 * process of the group remains with no request waiting for
-+	 * completion.
-+	 *
-+	 * Even this simpler decrement strategy requires a little
-+	 * carefulness: to avoid multiple decrements, we flag a group,
-+	 * more precisely an entity representing a group, as still
-+	 * counted in num_groups_with_pending_reqs when it becomes
-+	 * inactive. Then, when the first descendant queue of the
-+	 * entity remains with no request waiting for completion,
-+	 * num_groups_with_pending_reqs is decremented, and this flag
-+	 * is reset. After this flag is reset for the entity,
-+	 * num_groups_with_pending_reqs won't be decremented any
-+	 * longer in case a new descendant queue of the entity remains
-+	 * with no request waiting for completion.
-+	 */
-+	unsigned int num_groups_with_pending_reqs;
-+
-+	/*
-+	 * Per-class (RT, BE, IDLE) number of bfq_queues containing
-+	 * requests (including the queue in service, even if it is
-+	 * idling).
-+	 */
-+	unsigned int busy_queues[3];
-+	/* number of weight-raised busy @bfq_queues */
-+	int wr_busy_queues;
-+	/* number of queued requests */
-+	int queued;
-+	/* number of requests dispatched and waiting for completion */
-+	int rq_in_driver;
-+
-+	/*
-+	 * Maximum number of requests in driver in the last
-+	 * @hw_tag_samples completed requests.
-+	 */
-+	int max_rq_in_driver;
-+	/* number of samples used to calculate hw_tag */
-+	int hw_tag_samples;
-+	/* flag set to one if the driver is showing a queueing behavior */
-+	int hw_tag;
-+
-+	/* number of budgets assigned */
-+	int budgets_assigned;
-+
-+	/*
-+	 * Timer set when idling (waiting) for the next request from
-+	 * the queue in service.
-+	 */
-+	struct hrtimer idle_slice_timer;
-+
-+	/* bfq_queue in service */
-+	struct bfq_queue *in_service_queue;
-+
-+	/* on-disk position of the last served request */
-+	sector_t last_position;
-+
-+	/* position of the last served request for the in-service queue */
-+	sector_t in_serv_last_pos;
-+
-+	/* time of last request completion (ns) */
-+	u64 last_completion;
-+
-+	/* time of first rq dispatch in current observation interval (ns) */
-+	u64 first_dispatch;
-+	/* time of last rq dispatch in current observation interval (ns) */
-+	u64 last_dispatch;
-+
-+	/* beginning of the last budget */
-+	ktime_t last_budget_start;
-+	/* beginning of the last idle slice */
-+	ktime_t last_idling_start;
-+
-+	/* number of samples in current observation interval */
-+	int peak_rate_samples;
-+	/* num of samples of seq dispatches in current observation interval */
-+	u32 sequential_samples;
-+	/* total num of sectors transferred in current observation interval */
-+	u64 tot_sectors_dispatched;
-+	/* max rq size seen during current observation interval (sectors) */
-+	u32 last_rq_max_size;
-+	/* time elapsed from first dispatch in current observ. interval (us) */
-+	u64 delta_from_first;
-+	/*
-+	 * Current estimate of the device peak rate, measured in
-+	 * [(sectors/usec) / 2^BFQ_RATE_SHIFT]. The left-shift by
-+	 * BFQ_RATE_SHIFT is performed to increase precision in
-+	 * fixed-point calculations.
-+	 */
-+	u32 peak_rate;
-+
-+	/* maximum budget allotted to a bfq_queue before rescheduling */
-+	int bfq_max_budget;
-+
-+	/* list of all the bfq_queues active on the device */
-+	struct list_head active_list;
-+	/* list of all the bfq_queues idle on the device */
-+	struct list_head idle_list;
-+
-+	/*
-+	 * Timeout for async/sync requests; when it fires, requests
-+	 * are served in fifo order.
-+	 */
-+	u64 bfq_fifo_expire[2];
-+	/* weight of backward seeks wrt forward ones */
-+	unsigned int bfq_back_penalty;
-+	/* maximum allowed backward seek */
-+	unsigned int bfq_back_max;
-+	/* maximum idling time */
-+	u32 bfq_slice_idle;
-+
-+	/* user-configured max budget value (0 for auto-tuning) */
-+	int bfq_user_max_budget;
-+	/*
-+	 * Timeout for bfq_queues to consume their budget; used to
-+	 * prevent seeky queues from imposing long latencies to
-+	 * sequential or quasi-sequential ones (this also implies that
-+	 * seeky queues cannot receive guarantees in the service
-+	 * domain; after a timeout they are charged for the time they
-+	 * have been in service, to preserve fairness among them, but
-+	 * without service-domain guarantees).
-+	 */
-+	unsigned int bfq_timeout;
-+
-+	/*
-+	 * Number of consecutive requests that must be issued within
-+	 * the idle time slice to set again idling to a queue which
-+	 * was marked as non-I/O-bound (see the definition of the
-+	 * IO_bound flag for further details).
-+	 */
-+	unsigned int bfq_requests_within_timer;
-+
-+	/*
-+	 * Force device idling whenever needed to provide accurate
-+	 * service guarantees, without caring about throughput
-+	 * issues. CAVEAT: this may even increase latencies, in case
-+	 * of useless idling for processes that did stop doing I/O.
-+	 */
-+	bool strict_guarantees;
-+
-+	/*
-+	 * Last time at which a queue entered the current burst of
-+	 * queues being activated shortly after each other; for more
-+	 * details about this and the following parameters related to
-+	 * a burst of activations, see the comments on the function
-+	 * bfq_handle_burst.
-+	 */
-+	unsigned long last_ins_in_burst;
-+	/*
-+	 * Reference time interval used to decide whether a queue has
-+	 * been activated shortly after @last_ins_in_burst.
-+	 */
-+	unsigned long bfq_burst_interval;
-+	/* number of queues in the current burst of queue activations */
-+	int burst_size;
-+
-+	/* common parent entity for the queues in the burst */
-+	struct bfq_entity *burst_parent_entity;
-+	/* Maximum burst size above which the current queue-activation
-+	 * burst is deemed as 'large'.
-+	 */
-+	unsigned long bfq_large_burst_thresh;
-+	/* true if a large queue-activation burst is in progress */
-+	bool large_burst;
-+	/*
-+	 * Head of the burst list (as for the above fields, more
-+	 * details in the comments on the function bfq_handle_burst).
-+	 */
-+	struct hlist_head burst_list;
-+
-+	/* if set to true, low-latency heuristics are enabled */
-+	bool low_latency;
-+	/*
-+	 * Maximum factor by which the weight of a weight-raised queue
-+	 * is multiplied.
-+	 */
-+	unsigned int bfq_wr_coeff;
-+	/* maximum duration of a weight-raising period (jiffies) */
-+	unsigned int bfq_wr_max_time;
-+
-+	/* Maximum weight-raising duration for soft real-time processes */
-+	unsigned int bfq_wr_rt_max_time;
-+	/*
-+	 * Minimum idle period after which weight-raising may be
-+	 * reactivated for a queue (in jiffies).
-+	 */
-+	unsigned int bfq_wr_min_idle_time;
-+	/*
-+	 * Minimum period between request arrivals after which
-+	 * weight-raising may be reactivated for an already busy async
-+	 * queue (in jiffies).
-+	 */
-+	unsigned long bfq_wr_min_inter_arr_async;
-+
-+	/* Max service-rate for a soft real-time queue, in sectors/sec */
-+	unsigned int bfq_wr_max_softrt_rate;
-+	/*
-+	 * Cached value of the product ref_rate*ref_wr_duration, used
-+	 * for computing the maximum duration of weight raising
-+	 * automatically.
-+	 */
-+	u64 rate_dur_prod;
-+
-+	/* fallback dummy bfqq for extreme OOM conditions */
-+	struct bfq_queue oom_bfqq;
-+
-+	spinlock_t lock;
-+
-+	/*
-+	 * bic associated with the task issuing current bio for
-+	 * merging. This and the next field are used as a support to
-+	 * be able to perform the bic lookup, needed by bio-merge
-+	 * functions, before the scheduler lock is taken, and thus
-+	 * avoid taking the request-queue lock while the scheduler
-+	 * lock is being held.
-+	 */
-+	struct bfq_io_cq *bio_bic;
-+	/* bfqq associated with the task issuing current bio for merging */
-+	struct bfq_queue *bio_bfqq;
-+	/* Extra flag used only for TESTING */
-+	bool bio_bfqq_set;
-+
-+	/*
-+	 * Depth limits used in bfq_limit_depth (see comments on the
-+	 * function)
-+	 */
-+	unsigned int word_depths[2][2];
-+};
-+
-+enum bfqq_state_flags {
-+	BFQ_BFQQ_FLAG_just_created = 0,	/* queue just allocated */
-+	BFQ_BFQQ_FLAG_busy,		/* has requests or is in service */
-+	BFQ_BFQQ_FLAG_wait_request,	/* waiting for a request */
-+	BFQ_BFQQ_FLAG_non_blocking_wait_rq, /*
-+					     * waiting for a request
-+					     * without idling the device
-+					     */
-+	BFQ_BFQQ_FLAG_fifo_expire,	/* FIFO checked in this slice */
-+	BFQ_BFQQ_FLAG_has_short_ttime,	/* queue has a short think time */
-+	BFQ_BFQQ_FLAG_sync,		/* synchronous queue */
-+	BFQ_BFQQ_FLAG_IO_bound,		/*
-+					 * bfqq has timed-out at least once
-+					 * having consumed at most 2/10 of
-+					 * its budget
-+					 */
-+	BFQ_BFQQ_FLAG_in_large_burst,	/*
-+					 * bfqq activated in a large burst,
-+					 * see comments to bfq_handle_burst.
-+					 */
-+	BFQ_BFQQ_FLAG_softrt_update,	/*
-+					 * may need softrt-next-start
-+					 * update
-+					 */
-+	BFQ_BFQQ_FLAG_coop,		/* bfqq is shared */
-+	BFQ_BFQQ_FLAG_split_coop	/* shared bfqq will be split */
-+};
-+
-+#define BFQ_BFQQ_FNS(name)						\
-+static void bfq_mark_bfqq_##name(struct bfq_queue *bfqq)		\
-+{									\
-+	(bfqq)->flags |= (1 << BFQ_BFQQ_FLAG_##name);			\
-+}									\
-+static void bfq_clear_bfqq_##name(struct bfq_queue *bfqq)		\
-+{									\
-+	(bfqq)->flags &= ~(1 << BFQ_BFQQ_FLAG_##name);			\
-+}									\
-+static int bfq_bfqq_##name(const struct bfq_queue *bfqq)		\
-+{									\
-+	return ((bfqq)->flags & (1 << BFQ_BFQQ_FLAG_##name)) != 0;	\
-+}
-+
-+BFQ_BFQQ_FNS(just_created);
-+BFQ_BFQQ_FNS(busy);
-+BFQ_BFQQ_FNS(wait_request);
-+BFQ_BFQQ_FNS(non_blocking_wait_rq);
-+BFQ_BFQQ_FNS(fifo_expire);
-+BFQ_BFQQ_FNS(has_short_ttime);
-+BFQ_BFQQ_FNS(sync);
-+BFQ_BFQQ_FNS(IO_bound);
-+BFQ_BFQQ_FNS(in_large_burst);
-+BFQ_BFQQ_FNS(coop);
-+BFQ_BFQQ_FNS(split_coop);
-+BFQ_BFQQ_FNS(softrt_update);
-+#undef BFQ_BFQQ_FNS
-+
-+/* Logging facilities. */
-+#ifdef CONFIG_BFQ_REDIRECT_TO_CONSOLE
-+
-+static const char *checked_dev_name(const struct device *dev)
-+{
-+	static const char nodev[] = "nodev";
-+
-+	if (dev)
-+		return dev_name(dev);
-+
-+	return nodev;
-+}
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+static struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
-+static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
-+
-+#define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	do {			\
-+	pr_crit("%s bfq%d%c %s [%s] " fmt "\n",				\
-+		checked_dev_name((bfqd)->queue->backing_dev_info->dev),	\
-+		(bfqq)->pid,						\
-+		bfq_bfqq_sync((bfqq)) ? 'S' : 'A',			\
-+		bfqq_group(bfqq)->blkg_path, __func__, ##args);		\
-+} while (0)
-+
-+#define bfq_log_bfqg(bfqd, bfqg, fmt, args...)	do {			\
-+	pr_crit("%s %s [%s] " fmt "\n",					\
-+	checked_dev_name((bfqd)->queue->backing_dev_info->dev),		\
-+	bfqg->blkg_path, __func__, ##args);				\
-+} while (0)
-+
-+#else /* BFQ_GROUP_IOSCHED_ENABLED */
-+
-+#define bfq_log_bfqq(bfqd, bfqq, fmt, args...)				\
-+	pr_crit("%s bfq%d%c [%s] " fmt "\n",				\
-+		checked_dev_name((bfqd)->queue->backing_dev_info->dev),	\
-+		(bfqq)->pid, bfq_bfqq_sync((bfqq)) ? 'S' : 'A',		\
-+		__func__, ##args)
-+#define bfq_log_bfqg(bfqd, bfqg, fmt, args...)		do {} while (0)
-+
-+#endif /* BFQ_GROUP_IOSCHED_ENABLED */
-+
-+#define bfq_log(bfqd, fmt, args...) \
-+	pr_crit("%s bfq [%s] " fmt "\n",				\
-+		checked_dev_name((bfqd)->queue->backing_dev_info->dev),	\
-+		__func__, ##args)
-+
-+#else /* CONFIG_BFQ_REDIRECT_TO_CONSOLE */
-+
-+#if !defined(CONFIG_BLK_DEV_IO_TRACE)
-+
-+/* Avoid possible "unused-variable" warning. See commit message. */
-+
-+#define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	((void) (bfqq))
-+
-+#define bfq_log_bfqg(bfqd, bfqg, fmt, args...)	((void) (bfqg))
-+
-+#define bfq_log(bfqd, fmt, args...)		do {} while (0)
-+
-+#else /* CONFIG_BLK_DEV_IO_TRACE */
-+
-+#include <linux/blktrace_api.h>
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+static struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
-+static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
-+
-+#define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	do {			\
-+	blk_add_trace_msg((bfqd)->queue, "bfq%d%c %s [%s] " fmt, \
-+			  (bfqq)->pid,			  \
-+			  bfq_bfqq_sync((bfqq)) ? 'S' : 'A',	\
-+			  bfqq_group(bfqq)->blkg_path, __func__, ##args); \
-+} while (0)
-+
-+#define bfq_log_bfqg(bfqd, bfqg, fmt, args...)	do {			\
-+	blk_add_trace_msg((bfqd)->queue, "%s [%s] " fmt, bfqg->blkg_path, \
-+	__func__, ##args);\
-+} while (0)
-+
-+#else /* BFQ_GROUP_IOSCHED_ENABLED */
-+
-+#define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	\
-+	blk_add_trace_msg((bfqd)->queue, "bfq%d%c [%s] " fmt, (bfqq)->pid, \
-+			bfq_bfqq_sync((bfqq)) ? 'S' : 'A',		\
-+				__func__, ##args)
-+#define bfq_log_bfqg(bfqd, bfqg, fmt, args...)		do {} while (0)
-+
-+#endif /* BFQ_GROUP_IOSCHED_ENABLED */
-+
-+#define bfq_log(bfqd, fmt, args...) \
-+	blk_add_trace_msg((bfqd)->queue, "bfq [%s] " fmt, __func__, ##args)
-+
-+#endif /* CONFIG_BLK_DEV_IO_TRACE */
-+#endif /* CONFIG_BFQ_REDIRECT_TO_CONSOLE */
-+
-+/* Expiration reasons. */
-+enum bfqq_expiration {
-+	BFQ_BFQQ_TOO_IDLE = 0,		/*
-+					 * queue has been idling for
-+					 * too long
-+					 */
-+	BFQ_BFQQ_BUDGET_TIMEOUT,	/* budget took too long to be used */
-+	BFQ_BFQQ_BUDGET_EXHAUSTED,	/* budget consumed */
-+	BFQ_BFQQ_NO_MORE_REQUESTS,	/* the queue has no more requests */
-+	BFQ_BFQQ_PREEMPTED		/* preemption in progress */
-+};
-+
-+
-+struct bfqg_stats {
-+#if defined(BFQ_GROUP_IOSCHED_ENABLED) &&  defined(CONFIG_DEBUG_BLK_CGROUP)
-+	/* number of ios merged */
-+	struct blkg_rwstat		merged;
-+	/* total time spent on device in ns, may not be accurate w/ queueing */
-+	struct blkg_rwstat		service_time;
-+	/* total time spent waiting in scheduler queue in ns */
-+	struct blkg_rwstat		wait_time;
-+	/* number of IOs queued up */
-+	struct blkg_rwstat		queued;
-+	/* total disk time and nr sectors dispatched by this group */
-+	struct blkg_stat		time;
-+	/* sum of number of ios queued across all samples */
-+	struct blkg_stat		avg_queue_size_sum;
-+	/* count of samples taken for average */
-+	struct blkg_stat		avg_queue_size_samples;
-+	/* how many times this group has been removed from service tree */
-+	struct blkg_stat		dequeue;
-+	/* total time spent waiting for it to be assigned a timeslice. */
-+	struct blkg_stat		group_wait_time;
-+	/* time spent idling for this blkcg_gq */
-+	struct blkg_stat		idle_time;
-+	/* total time with empty current active q with other requests queued */
-+	struct blkg_stat		empty_time;
-+	/* fields after this shouldn't be cleared on stat reset */
-+	u64				start_group_wait_time;
-+	u64				start_idle_time;
-+	u64				start_empty_time;
-+	uint16_t			flags;
-+#endif /* BFQ_GROUP_IOSCHED_ENABLED && CONFIG_DEBUG_BLK_CGROUP */
-+};
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+/*
-+ * struct bfq_group_data - per-blkcg storage for the blkio subsystem.
-+ *
-+ * @ps: @blkcg_policy_storage that this structure inherits
-+ * @weight: weight of the bfq_group
-+ */
-+struct bfq_group_data {
-+	/* must be the first member */
-+	struct blkcg_policy_data pd;
-+
-+	unsigned int weight;
-+};
-+
-+/**
-+ * struct bfq_group - per (device, cgroup) data structure.
-+ * @entity: schedulable entity to insert into the parent group sched_data.
-+ * @sched_data: own sched_data, to contain child entities (they may be
-+ *              both bfq_queues and bfq_groups).
-+ * @bfqd: the bfq_data for the device this group acts upon.
-+ * @async_bfqq: array of async queues for all the tasks belonging to
-+ *              the group, one queue per ioprio value per ioprio_class,
-+ *              except for the idle class that has only one queue.
-+ * @async_idle_bfqq: async queue for the idle class (ioprio is ignored).
-+ * @my_entity: pointer to @entity, %NULL for the toplevel group; used
-+ *             to avoid too many special cases during group creation/
-+ *             migration.
-+ * @active_entities: number of active entities belonging to the group;
-+ *                   unused for the root group. Used to know whether there
-+ *                   are groups with more than one active @bfq_entity
-+ *                   (see the comments to the function
-+ *                   bfq_bfqq_may_idle()).
-+ * @rq_pos_tree: rbtree sorted by next_request position, used when
-+ *               determining if two or more queues have interleaving
-+ *               requests (see bfq_find_close_cooperator()).
-+ *
-+ * Each (device, cgroup) pair has its own bfq_group, i.e., for each cgroup
-+ * there is a set of bfq_groups, each one collecting the lower-level
-+ * entities belonging to the group that are acting on the same device.
-+ *
-+ * Locking works as follows:
-+ *    o @bfqd is protected by the queue lock, RCU is used to access it
-+ *      from the readers.
-+ *    o All the other fields are protected by the @bfqd queue lock.
-+ */
-+struct bfq_group {
-+	/* must be the first member */
-+	struct blkg_policy_data pd;
-+
-+	/* cached path for this blkg (see comments in bfq_bic_update_cgroup) */
-+	char blkg_path[128];
-+
-+	/* reference counter (see comments in bfq_bic_update_cgroup) */
-+	int ref;
-+
-+	struct bfq_entity entity;
-+	struct bfq_sched_data sched_data;
-+
-+	void *bfqd;
-+
-+	struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
-+	struct bfq_queue *async_idle_bfqq;
-+
-+	struct bfq_entity *my_entity;
-+
-+	int active_entities;
-+
-+	struct rb_root rq_pos_tree;
-+
-+	struct bfqg_stats stats;
-+};
-+
-+#else
-+struct bfq_group {
-+	struct bfq_sched_data sched_data;
-+
-+	struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
-+	struct bfq_queue *async_idle_bfqq;
-+
-+	struct rb_root rq_pos_tree;
-+};
-+#endif
-+
-+static struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity);
-+
-+static unsigned int bfq_class_idx(struct bfq_entity *entity)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+
-+	return bfqq ? bfqq->ioprio_class - 1 :
-+		BFQ_DEFAULT_GRP_CLASS - 1;
-+}
-+
-+static unsigned int bfq_tot_busy_queues(struct bfq_data *bfqd)
-+{
-+	return bfqd->busy_queues[0] + bfqd->busy_queues[1] +
-+		bfqd->busy_queues[2];
-+}
-+
-+static struct bfq_service_tree *
-+bfq_entity_service_tree(struct bfq_entity *entity)
-+{
-+	struct bfq_sched_data *sched_data = entity->sched_data;
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+	unsigned int idx = bfq_class_idx(entity);
-+
-+	BUG_ON(idx >= BFQ_IOPRIO_CLASSES);
-+	BUG_ON(sched_data == NULL);
-+
-+	if (bfqq)
-+		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			     "%p %d",
-+			     sched_data->service_tree + idx, idx);
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	else {
-+		struct bfq_group *bfqg =
-+			container_of(entity, struct bfq_group, entity);
-+
-+		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+			     "%p %d",
-+			     sched_data->service_tree + idx, idx);
-+	}
-+#endif
-+	return sched_data->service_tree + idx;
-+}
-+
-+static struct bfq_queue *bic_to_bfqq(struct bfq_io_cq *bic, bool is_sync)
-+{
-+	return bic->bfqq[is_sync];
-+}
-+
-+static void bic_set_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq,
-+			 bool is_sync)
-+{
-+	bic->bfqq[is_sync] = bfqq;
-+}
-+
-+static struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic)
-+{
-+	return bic->icq.q->elevator->elevator_data;
-+}
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+
-+static struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq)
-+{
-+	struct bfq_entity *group_entity = bfqq->entity.parent;
-+
-+	if (!group_entity)
-+		group_entity = &bfqq->bfqd->root_group->entity;
-+
-+	return container_of(group_entity, struct bfq_group, entity);
-+}
-+
-+#else
-+
-+static struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq)
-+{
-+	return bfqq->bfqd->root_group;
-+}
-+
-+#endif
-+
-+static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio);
-+static void bfq_put_queue(struct bfq_queue *bfqq);
-+static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd,
-+				       struct bio *bio, bool is_sync,
-+				       struct bfq_io_cq *bic);
-+static void bfq_end_wr_async_queues(struct bfq_data *bfqd,
-+				    struct bfq_group *bfqg);
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);
-+#endif
-+static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq);
-+
-+#endif /* _BFQ_H */
-diff --git a/block/bfq-sched.c b/block/bfq-sched.c
-new file mode 100644
-index 000000000000..7a4923231106
---- /dev/null
-+++ b/block/bfq-sched.c
-@@ -0,0 +1,2077 @@
-+/*
-+ * BFQ: Hierarchical B-WF2Q+ scheduler.
-+ *
-+ * Based on ideas and code from CFQ:
-+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
-+ *
-+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
-+ *		      Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2016 Paolo Valente <paolo.valente@linaro.org>
-+ */
-+
-+static struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
-+
-+/**
-+ * bfq_gt - compare two timestamps.
-+ * @a: first ts.
-+ * @b: second ts.
-+ *
-+ * Return @a > @b, dealing with wrapping correctly.
-+ */
-+static int bfq_gt(u64 a, u64 b)
-+{
-+	return (s64)(a - b) > 0;
-+}
-+
-+static struct bfq_entity *bfq_root_active_entity(struct rb_root *tree)
-+{
-+	struct rb_node *node = tree->rb_node;
-+
-+	return rb_entry(node, struct bfq_entity, rb_node);
-+}
-+
-+static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd,
-+						 bool expiration);
-+
-+static bool bfq_update_parent_budget(struct bfq_entity *next_in_service);
-+
-+/**
-+ * bfq_update_next_in_service - update sd->next_in_service
-+ * @sd: sched_data for which to perform the update.
-+ * @new_entity: if not NULL, pointer to the entity whose activation,
-+ *		requeueing or repositionig triggered the invocation of
-+ *		this function.
-+ * @expiration: id true, this function is being invoked after the
-+ *		expiration of the in-service entity
-+ *
-+ * This function is called to update sd->next_in_service, which, in
-+ * its turn, may change as a consequence of the insertion or
-+ * extraction of an entity into/from one of the active trees of
-+ * sd. These insertions/extractions occur as a consequence of
-+ * activations/deactivations of entities, with some activations being
-+ * 'true' activations, and other activations being requeueings (i.e.,
-+ * implementing the second, requeueing phase of the mechanism used to
-+ * reposition an entity in its active tree; see comments on
-+ * __bfq_activate_entity and __bfq_requeue_entity for details). In
-+ * both the last two activation sub-cases, new_entity points to the
-+ * just activated or requeued entity.
-+ *
-+ * Returns true if sd->next_in_service changes in such a way that
-+ * entity->parent may become the next_in_service for its parent
-+ * entity.
-+ */
-+static bool bfq_update_next_in_service(struct bfq_sched_data *sd,
-+				       struct bfq_entity *new_entity,
-+				       bool expiration)
-+{
-+	struct bfq_entity *next_in_service = sd->next_in_service;
-+	struct bfq_queue *bfqq;
-+	bool parent_sched_may_change = false;
-+	bool change_without_lookup = false;
-+
-+	/*
-+	 * If this update is triggered by the activation, requeueing
-+	 * or repositiong of an entity that does not coincide with
-+	 * sd->next_in_service, then a full lookup in the active tree
-+	 * can be avoided. In fact, it is enough to check whether the
-+	 * just-modified entity has the same priority as
-+	 * sd->next_in_service, is eligible and has a lower virtual
-+	 * finish time than sd->next_in_service. If this compound
-+	 * condition holds, then the new entity becomes the new
-+	 * next_in_service. Otherwise no change is needed.
-+	 */
-+	if (new_entity && new_entity != sd->next_in_service) {
-+		/*
-+		 * Flag used to decide whether to replace
-+		 * sd->next_in_service with new_entity. Tentatively
-+		 * set to true, and left as true if
-+		 * sd->next_in_service is NULL.
-+		 */
-+		change_without_lookup = true;
-+
-+		/*
-+		 * If there is already a next_in_service candidate
-+		 * entity, then compare timestamps to decide whether
-+		 * to replace sd->service_tree with new_entity.
-+		 */
-+		if (next_in_service) {
-+			unsigned int new_entity_class_idx =
-+				bfq_class_idx(new_entity);
-+			struct bfq_service_tree *st =
-+				sd->service_tree + new_entity_class_idx;
-+
-+			change_without_lookup =
-+				(new_entity_class_idx ==
-+				 bfq_class_idx(next_in_service)
-+				 &&
-+				 !bfq_gt(new_entity->start, st->vtime)
-+				 &&
-+				 bfq_gt(next_in_service->finish,
-+					new_entity->finish));
-+		}
-+
-+		if (change_without_lookup) {
-+			next_in_service = new_entity;
-+			bfqq = bfq_entity_to_bfqq(next_in_service);
-+
-+			if (bfqq)
-+				bfq_log_bfqq(bfqq->bfqd, bfqq,
-+				"chose without lookup");
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+			else {
-+				struct bfq_group *bfqg =
-+					container_of(next_in_service,
-+						     struct bfq_group, entity);
-+
-+				bfq_log_bfqg((struct bfq_data*)bfqg->bfqd, bfqg,
-+				"chose without lookup");
-+			}
-+#endif
-+		}
-+	}
-+
-+	if (!change_without_lookup) /* lookup needed */
-+		next_in_service = bfq_lookup_next_entity(sd, expiration);
-+
-+	if (next_in_service) {
-+		bool new_budget_triggers_change =
-+			bfq_update_parent_budget(next_in_service);
-+
-+		parent_sched_may_change = !sd->next_in_service ||
-+			new_budget_triggers_change;
-+	}
-+
-+	sd->next_in_service = next_in_service;
-+
-+	if (!next_in_service)
-+		return parent_sched_may_change;
-+
-+	bfqq = bfq_entity_to_bfqq(next_in_service);
-+	if (bfqq)
-+		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			     "chosen this queue");
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	else {
-+		struct bfq_group *bfqg =
-+			container_of(next_in_service,
-+				     struct bfq_group, entity);
-+
-+		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+			     "chosen this entity");
-+	}
-+#endif
-+	return parent_sched_may_change;
-+}
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+/* both next loops stop at one of the child entities of the root group */
-+#define for_each_entity(entity)				\
-+	for (; entity ; entity = entity->parent)
-+
-+/*
-+ * For each iteration, compute parent in advance, so as to be safe if
-+ * entity is deallocated during the iteration. Such a deallocation may
-+ * happen as a consequence of a bfq_put_queue that frees the bfq_queue
-+ * containing entity.
-+ */
-+#define for_each_entity_safe(entity, parent)				\
-+	for (; entity && ({ parent = entity->parent; 1; }); entity = parent)
-+
-+/*
-+ * Returns true if this budget changes may let next_in_service->parent
-+ * become the next_in_service entity for its parent entity.
-+ */
-+static bool bfq_update_parent_budget(struct bfq_entity *next_in_service)
-+{
-+	struct bfq_entity *bfqg_entity;
-+	struct bfq_group *bfqg;
-+	struct bfq_sched_data *group_sd;
-+	bool ret = false;
-+
-+	BUG_ON(!next_in_service);
-+
-+	group_sd = next_in_service->sched_data;
-+
-+	bfqg = container_of(group_sd, struct bfq_group, sched_data);
-+	/*
-+	 * bfq_group's my_entity field is not NULL only if the group
-+	 * is not the root group. We must not touch the root entity
-+	 * as it must never become an in-service entity.
-+	 */
-+	bfqg_entity = bfqg->my_entity;
-+	if (bfqg_entity) {
-+		if (bfqg_entity->budget > next_in_service->budget)
-+			ret = true;
-+		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+			"old budg: %d, new budg: %d",
-+			bfqg_entity->budget, next_in_service->budget);
-+		bfqg_entity->budget = next_in_service->budget;
-+	}
-+
-+	return ret;
-+}
-+
-+/*
-+ * This function tells whether entity stops being a candidate for next
-+ * service, according to the restrictive definition of the field
-+ * next_in_service. In particular, this function is invoked for an
-+ * entity that is about to be set in service.
-+ *
-+ * If entity is a queue, then the entity is no longer a candidate for
-+ * next service according to the that definition, because entity is
-+ * about to become the in-service queue. This function then returns
-+ * true if entity is a queue.
-+ *
-+ * In contrast, entity could still be a candidate for next service if
-+ * it is not a queue, and has more than one active child. In fact,
-+ * even if one of its children is about to be set in service, other
-+ * active children may still be the next to serve, for the parent
-+ * entity, even according to the above definition. As a consequence, a
-+ * non-queue entity is not a candidate for next-service only if it has
-+ * only one active child. And only if this condition holds, then this
-+ * function returns true for a non-queue entity.
-+ */
-+static bool bfq_no_longer_next_in_service(struct bfq_entity *entity)
-+{
-+	struct bfq_group *bfqg;
-+
-+	if (bfq_entity_to_bfqq(entity))
-+		return true;
-+
-+	bfqg = container_of(entity, struct bfq_group, entity);
-+
-+	BUG_ON(bfqg == ((struct bfq_data *)(bfqg->bfqd))->root_group);
-+	BUG_ON(bfqg->active_entities == 0);
-+	/*
-+	 * The field active_entities does not always contain the
-+	 * actual number of active children entities: it happens to
-+	 * not account for the in-service entity in case the latter is
-+	 * removed from its active tree (which may get done after
-+	 * invoking the function bfq_no_longer_next_in_service in
-+	 * bfq_get_next_queue). Fortunately, here, i.e., while
-+	 * bfq_no_longer_next_in_service is not yet completed in
-+	 * bfq_get_next_queue, bfq_active_extract has not yet been
-+	 * invoked, and thus active_entities still coincides with the
-+	 * actual number of active entities.
-+	 */
-+	if (bfqg->active_entities == 1)
-+		return true;
-+
-+	return false;
-+}
-+
-+#else /* BFQ_GROUP_IOSCHED_ENABLED */
-+#define for_each_entity(entity)	\
-+	for (; entity ; entity = NULL)
-+
-+#define for_each_entity_safe(entity, parent) \
-+	for (parent = NULL; entity ; entity = parent)
-+
-+static bool bfq_update_parent_budget(struct bfq_entity *next_in_service)
-+{
-+	return false;
-+}
-+
-+static bool bfq_no_longer_next_in_service(struct bfq_entity *entity)
-+{
-+	return true;
-+}
-+
-+#endif /* BFQ_GROUP_IOSCHED_ENABLED */
-+
-+/*
-+ * Shift for timestamp calculations.  This actually limits the maximum
-+ * service allowed in one timestamp delta (small shift values increase it),
-+ * the maximum total weight that can be used for the queues in the system
-+ * (big shift values increase it), and the period of virtual time
-+ * wraparounds.
-+ */
-+#define WFQ_SERVICE_SHIFT	22
-+
-+static struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity)
-+{
-+	struct bfq_queue *bfqq = NULL;
-+
-+	BUG_ON(!entity);
-+
-+	if (!entity->my_sched_data)
-+		bfqq = container_of(entity, struct bfq_queue, entity);
-+
-+	return bfqq;
-+}
-+
-+
-+/**
-+ * bfq_delta - map service into the virtual time domain.
-+ * @service: amount of service.
-+ * @weight: scale factor (weight of an entity or weight sum).
-+ */
-+static u64 bfq_delta(unsigned long service, unsigned long weight)
-+{
-+	u64 d = (u64)service << WFQ_SERVICE_SHIFT;
-+
-+	do_div(d, weight);
-+	return d;
-+}
-+
-+/**
-+ * bfq_calc_finish - assign the finish time to an entity.
-+ * @entity: the entity to act upon.
-+ * @service: the service to be charged to the entity.
-+ */
-+static void bfq_calc_finish(struct bfq_entity *entity, unsigned long service)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+	unsigned long long start, finish, delta;
-+
-+	BUG_ON(entity->weight == 0);
-+
-+	entity->finish = entity->start +
-+		bfq_delta(service, entity->weight);
-+
-+	start = ((entity->start>>10)*1000)>>12;
-+	finish = ((entity->finish>>10)*1000)>>12;
-+	delta = ((bfq_delta(service, entity->weight)>>10)*1000)>>12;
-+
-+	if (bfqq) {
-+		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			"serv %lu, w %d",
-+			service, entity->weight);
-+		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			"start %llu, finish %llu, delta %llu",
-+			start, finish, delta);
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	} else {
-+		struct bfq_group *bfqg =
-+			container_of(entity, struct bfq_group, entity);
-+
-+		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+			"group: serv %lu, w %d",
-+			     service, entity->weight);
-+		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+			"group: start %llu, finish %llu, delta %llu",
-+			start, finish, delta);
-+#endif
-+	}
-+}
-+
-+/**
-+ * bfq_entity_of - get an entity from a node.
-+ * @node: the node field of the entity.
-+ *
-+ * Convert a node pointer to the relative entity.  This is used only
-+ * to simplify the logic of some functions and not as the generic
-+ * conversion mechanism because, e.g., in the tree walking functions,
-+ * the check for a %NULL value would be redundant.
-+ */
-+static struct bfq_entity *bfq_entity_of(struct rb_node *node)
-+{
-+	struct bfq_entity *entity = NULL;
-+
-+	if (node)
-+		entity = rb_entry(node, struct bfq_entity, rb_node);
-+
-+	return entity;
-+}
-+
-+/**
-+ * bfq_extract - remove an entity from a tree.
-+ * @root: the tree root.
-+ * @entity: the entity to remove.
-+ */
-+static void bfq_extract(struct rb_root *root, struct bfq_entity *entity)
-+{
-+	BUG_ON(entity->tree != root);
-+
-+	entity->tree = NULL;
-+	rb_erase(&entity->rb_node, root);
-+}
-+
-+/**
-+ * bfq_idle_extract - extract an entity from the idle tree.
-+ * @st: the service tree of the owning @entity.
-+ * @entity: the entity being removed.
-+ */
-+static void bfq_idle_extract(struct bfq_service_tree *st,
-+			     struct bfq_entity *entity)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+	struct rb_node *next;
-+
-+	BUG_ON(entity->tree != &st->idle);
-+
-+	if (entity == st->first_idle) {
-+		next = rb_next(&entity->rb_node);
-+		st->first_idle = bfq_entity_of(next);
-+	}
-+
-+	if (entity == st->last_idle) {
-+		next = rb_prev(&entity->rb_node);
-+		st->last_idle = bfq_entity_of(next);
-+	}
-+
-+	bfq_extract(&st->idle, entity);
-+
-+	if (bfqq)
-+		list_del(&bfqq->bfqq_list);
-+}
-+
-+/**
-+ * bfq_insert - generic tree insertion.
-+ * @root: tree root.
-+ * @entity: entity to insert.
-+ *
-+ * This is used for the idle and the active tree, since they are both
-+ * ordered by finish time.
-+ */
-+static void bfq_insert(struct rb_root *root, struct bfq_entity *entity)
-+{
-+	struct bfq_entity *entry;
-+	struct rb_node **node = &root->rb_node;
-+	struct rb_node *parent = NULL;
-+
-+	BUG_ON(entity->tree);
-+
-+	while (*node) {
-+		parent = *node;
-+		entry = rb_entry(parent, struct bfq_entity, rb_node);
-+
-+		if (bfq_gt(entry->finish, entity->finish))
-+			node = &parent->rb_left;
-+		else
-+			node = &parent->rb_right;
-+	}
-+
-+	rb_link_node(&entity->rb_node, parent, node);
-+	rb_insert_color(&entity->rb_node, root);
-+
-+	entity->tree = root;
-+}
-+
-+/**
-+ * bfq_update_min - update the min_start field of a entity.
-+ * @entity: the entity to update.
-+ * @node: one of its children.
-+ *
-+ * This function is called when @entity may store an invalid value for
-+ * min_start due to updates to the active tree.  The function  assumes
-+ * that the subtree rooted at @node (which may be its left or its right
-+ * child) has a valid min_start value.
-+ */
-+static void bfq_update_min(struct bfq_entity *entity, struct rb_node *node)
-+{
-+	struct bfq_entity *child;
-+
-+	if (node) {
-+		child = rb_entry(node, struct bfq_entity, rb_node);
-+		if (bfq_gt(entity->min_start, child->min_start))
-+			entity->min_start = child->min_start;
-+	}
-+}
-+
-+/**
-+ * bfq_update_active_node - recalculate min_start.
-+ * @node: the node to update.
-+ *
-+ * @node may have changed position or one of its children may have moved,
-+ * this function updates its min_start value.  The left and right subtrees
-+ * are assumed to hold a correct min_start value.
-+ */
-+static void bfq_update_active_node(struct rb_node *node)
-+{
-+	struct bfq_entity *entity = rb_entry(node, struct bfq_entity, rb_node);
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+
-+	entity->min_start = entity->start;
-+	bfq_update_min(entity, node->rb_right);
-+	bfq_update_min(entity, node->rb_left);
-+
-+	if (bfqq) {
-+		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			     "new min_start %llu",
-+			     ((entity->min_start>>10)*1000)>>12);
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	} else {
-+		struct bfq_group *bfqg =
-+			container_of(entity, struct bfq_group, entity);
-+
-+		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+			     "new min_start %llu",
-+			     ((entity->min_start>>10)*1000)>>12);
-+#endif
-+	}
-+}
-+
-+/**
-+ * bfq_update_active_tree - update min_start for the whole active tree.
-+ * @node: the starting node.
-+ *
-+ * @node must be the deepest modified node after an update.  This function
-+ * updates its min_start using the values held by its children, assuming
-+ * that they did not change, and then updates all the nodes that may have
-+ * changed in the path to the root.  The only nodes that may have changed
-+ * are the ones in the path or their siblings.
-+ */
-+static void bfq_update_active_tree(struct rb_node *node)
-+{
-+	struct rb_node *parent;
-+
-+up:
-+	bfq_update_active_node(node);
-+
-+	parent = rb_parent(node);
-+	if (!parent)
-+		return;
-+
-+	if (node == parent->rb_left && parent->rb_right)
-+		bfq_update_active_node(parent->rb_right);
-+	else if (parent->rb_left)
-+		bfq_update_active_node(parent->rb_left);
-+
-+	node = parent;
-+	goto up;
-+}
-+
-+static void bfq_weights_tree_add(struct bfq_data *bfqd,
-+				 struct bfq_queue *bfqq,
-+				 struct rb_root *root);
-+
-+static void __bfq_weights_tree_remove(struct bfq_data *bfqd,
-+				      struct bfq_queue *bfqq,
-+				      struct rb_root *root);
-+
-+static void bfq_weights_tree_remove(struct bfq_data *bfqd,
-+				    struct bfq_queue *bfqq);
-+
-+
-+/**
-+ * bfq_active_insert - insert an entity in the active tree of its
-+ *                     group/device.
-+ * @st: the service tree of the entity.
-+ * @entity: the entity being inserted.
-+ *
-+ * The active tree is ordered by finish time, but an extra key is kept
-+ * per each node, containing the minimum value for the start times of
-+ * its children (and the node itself), so it's possible to search for
-+ * the eligible node with the lowest finish time in logarithmic time.
-+ */
-+static void bfq_active_insert(struct bfq_service_tree *st,
-+			      struct bfq_entity *entity)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+	struct rb_node *node = &entity->rb_node;
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	struct bfq_sched_data *sd = NULL;
-+	struct bfq_group *bfqg = NULL;
-+	struct bfq_data *bfqd = NULL;
-+#endif
-+
-+	bfq_insert(&st->active, entity);
-+
-+	if (node->rb_left)
-+		node = node->rb_left;
-+	else if (node->rb_right)
-+		node = node->rb_right;
-+
-+	bfq_update_active_tree(node);
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	sd = entity->sched_data;
-+	bfqg = container_of(sd, struct bfq_group, sched_data);
-+	BUG_ON(!bfqg);
-+	bfqd = (struct bfq_data *)bfqg->bfqd;
-+#endif
-+	if (bfqq)
-+		list_add(&bfqq->bfqq_list, &bfqq->bfqd->active_list);
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	if (bfqg != bfqd->root_group) {
-+		BUG_ON(!bfqg);
-+		BUG_ON(!bfqd);
-+		bfqg->active_entities++;
-+	}
-+#endif
-+}
-+
-+/**
-+ * bfq_ioprio_to_weight - calc a weight from an ioprio.
-+ * @ioprio: the ioprio value to convert.
-+ */
-+static unsigned short bfq_ioprio_to_weight(int ioprio)
-+{
-+	BUG_ON(ioprio < 0 || ioprio >= IOPRIO_BE_NR);
-+	return (IOPRIO_BE_NR - ioprio) * BFQ_WEIGHT_CONVERSION_COEFF;
-+}
-+
-+/**
-+ * bfq_weight_to_ioprio - calc an ioprio from a weight.
-+ * @weight: the weight value to convert.
-+ *
-+ * To preserve as much as possible the old only-ioprio user interface,
-+ * 0 is used as an escape ioprio value for weights (numerically) equal or
-+ * larger than IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF.
-+ */
-+static unsigned short bfq_weight_to_ioprio(int weight)
-+{
-+	BUG_ON(weight < BFQ_MIN_WEIGHT || weight > BFQ_MAX_WEIGHT);
-+	return IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF - weight < 0 ?
-+		0 : IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF - weight;
-+}
-+
-+static void bfq_get_entity(struct bfq_entity *entity)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+
-+	if (bfqq) {
-+		bfqq->ref++;
-+		bfq_log_bfqq(bfqq->bfqd, bfqq, "%p %d",
-+			     bfqq, bfqq->ref);
-+	}
-+}
-+
-+/**
-+ * bfq_find_deepest - find the deepest node that an extraction can modify.
-+ * @node: the node being removed.
-+ *
-+ * Do the first step of an extraction in an rb tree, looking for the
-+ * node that will replace @node, and returning the deepest node that
-+ * the following modifications to the tree can touch.  If @node is the
-+ * last node in the tree return %NULL.
-+ */
-+static struct rb_node *bfq_find_deepest(struct rb_node *node)
-+{
-+	struct rb_node *deepest;
-+
-+	if (!node->rb_right && !node->rb_left)
-+		deepest = rb_parent(node);
-+	else if (!node->rb_right)
-+		deepest = node->rb_left;
-+	else if (!node->rb_left)
-+		deepest = node->rb_right;
-+	else {
-+		deepest = rb_next(node);
-+		if (deepest->rb_right)
-+			deepest = deepest->rb_right;
-+		else if (rb_parent(deepest) != node)
-+			deepest = rb_parent(deepest);
-+	}
-+
-+	return deepest;
-+}
-+
-+/**
-+ * bfq_active_extract - remove an entity from the active tree.
-+ * @st: the service_tree containing the tree.
-+ * @entity: the entity being removed.
-+ */
-+static void bfq_active_extract(struct bfq_service_tree *st,
-+			       struct bfq_entity *entity)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+	struct rb_node *node;
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	struct bfq_sched_data *sd = NULL;
-+	struct bfq_group *bfqg = NULL;
-+	struct bfq_data *bfqd = NULL;
-+#endif
-+
-+	node = bfq_find_deepest(&entity->rb_node);
-+	bfq_extract(&st->active, entity);
-+
-+	if (node)
-+		bfq_update_active_tree(node);
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	sd = entity->sched_data;
-+	bfqg = container_of(sd, struct bfq_group, sched_data);
-+	BUG_ON(!bfqg);
-+	bfqd = (struct bfq_data *)bfqg->bfqd;
-+#endif
-+	if (bfqq)
-+		list_del(&bfqq->bfqq_list);
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	if (bfqg != bfqd->root_group) {
-+		BUG_ON(!bfqg);
-+		BUG_ON(!bfqd);
-+		BUG_ON(!bfqg->active_entities);
-+		bfqg->active_entities--;
-+	}
-+#endif
-+}
-+
-+/**
-+ * bfq_idle_insert - insert an entity into the idle tree.
-+ * @st: the service tree containing the tree.
-+ * @entity: the entity to insert.
-+ */
-+static void bfq_idle_insert(struct bfq_service_tree *st,
-+			    struct bfq_entity *entity)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+	struct bfq_entity *first_idle = st->first_idle;
-+	struct bfq_entity *last_idle = st->last_idle;
-+
-+	if (!first_idle || bfq_gt(first_idle->finish, entity->finish))
-+		st->first_idle = entity;
-+	if (!last_idle || bfq_gt(entity->finish, last_idle->finish))
-+		st->last_idle = entity;
-+
-+	bfq_insert(&st->idle, entity);
-+
-+	if (bfqq)
-+		list_add(&bfqq->bfqq_list, &bfqq->bfqd->idle_list);
-+}
-+
-+/**
-+ * bfq_forget_entity - do not consider entity any longer for scheduling
-+ * @st: the service tree.
-+ * @entity: the entity being removed.
-+ * @is_in_service: true if entity is currently the in-service entity.
-+ *
-+ * Forget everything about @entity. In addition, if entity represents
-+ * a queue, and the latter is not in service, then release the service
-+ * reference to the queue (the one taken through bfq_get_entity). In
-+ * fact, in this case, there is really no more service reference to
-+ * the queue, as the latter is also outside any service tree. If,
-+ * instead, the queue is in service, then __bfq_bfqd_reset_in_service
-+ * will take care of putting the reference when the queue finally
-+ * stops being served.
-+ */
-+static void bfq_forget_entity(struct bfq_service_tree *st,
-+			      struct bfq_entity *entity,
-+			      bool is_in_service)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+	BUG_ON(!entity->on_st);
-+
-+	entity->on_st = false;
-+	st->wsum -= entity->weight;
-+	if (bfqq && !is_in_service) {
-+		bfq_log_bfqq(bfqq->bfqd, bfqq, "(before): %p %d",
-+			     bfqq, bfqq->ref);
-+		bfq_put_queue(bfqq);
-+	}
-+}
-+
-+/**
-+ * bfq_put_idle_entity - release the idle tree ref of an entity.
-+ * @st: service tree for the entity.
-+ * @entity: the entity being released.
-+ */
-+static void bfq_put_idle_entity(struct bfq_service_tree *st,
-+				struct bfq_entity *entity)
-+{
-+	bfq_idle_extract(st, entity);
-+	bfq_forget_entity(st, entity,
-+			  entity == entity->sched_data->in_service_entity);
-+}
-+
-+/**
-+ * bfq_forget_idle - update the idle tree if necessary.
-+ * @st: the service tree to act upon.
-+ *
-+ * To preserve the global O(log N) complexity we only remove one entry here;
-+ * as the idle tree will not grow indefinitely this can be done safely.
-+ */
-+static void bfq_forget_idle(struct bfq_service_tree *st)
-+{
-+	struct bfq_entity *first_idle = st->first_idle;
-+	struct bfq_entity *last_idle = st->last_idle;
-+
-+	if (RB_EMPTY_ROOT(&st->active) && last_idle &&
-+	    !bfq_gt(last_idle->finish, st->vtime)) {
-+		/*
-+		 * Forget the whole idle tree, increasing the vtime past
-+		 * the last finish time of idle entities.
-+		 */
-+		st->vtime = last_idle->finish;
-+	}
-+
-+	if (first_idle && !bfq_gt(first_idle->finish, st->vtime))
-+		bfq_put_idle_entity(st, first_idle);
-+}
-+
-+/*
-+ * Update weight and priority of entity. If update_class_too is true,
-+ * then update the ioprio_class of entity too.
-+ *
-+ * The reason why the update of ioprio_class is controlled through the
-+ * last parameter is as follows. Changing the ioprio class of an
-+ * entity implies changing the destination service trees for that
-+ * entity. If such a change occurred when the entity is already on one
-+ * of the service trees for its previous class, then the state of the
-+ * entity would become more complex: none of the new possible service
-+ * trees for the entity, according to bfq_entity_service_tree(), would
-+ * match any of the possible service trees on which the entity
-+ * is. Complex operations involving these trees, such as entity
-+ * activations and deactivations, should take into account this
-+ * additional complexity.  To avoid this issue, this function is
-+ * invoked with update_class_too unset in the points in the code where
-+ * entity may happen to be on some tree.
-+ */
-+static struct bfq_service_tree *
-+__bfq_entity_update_weight_prio(struct bfq_service_tree *old_st,
-+				struct bfq_entity *entity,
-+				bool update_class_too)
-+{
-+	struct bfq_service_tree *new_st = old_st;
-+
-+	if (entity->prio_changed) {
-+		struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+		unsigned int prev_weight, new_weight;
-+		struct bfq_data *bfqd = NULL;
-+		struct rb_root *root;
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+		struct bfq_sched_data *sd;
-+		struct bfq_group *bfqg;
-+#endif
-+
-+		if (bfqq)
-+			bfqd = bfqq->bfqd;
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+		else {
-+			sd = entity->my_sched_data;
-+			bfqg = container_of(sd, struct bfq_group, sched_data);
-+			BUG_ON(!bfqg);
-+			bfqd = (struct bfq_data *)bfqg->bfqd;
-+			BUG_ON(!bfqd);
-+		}
-+#endif
-+
-+		BUG_ON(entity->tree && update_class_too);
-+		BUG_ON(old_st->wsum < entity->weight);
-+		old_st->wsum -= entity->weight;
-+
-+		if (entity->new_weight != entity->orig_weight) {
-+			if (entity->new_weight < BFQ_MIN_WEIGHT ||
-+			    entity->new_weight > BFQ_MAX_WEIGHT) {
-+				pr_crit("update_weight_prio: new_weight %d\n",
-+					entity->new_weight);
-+				if (entity->new_weight < BFQ_MIN_WEIGHT)
-+					entity->new_weight = BFQ_MIN_WEIGHT;
-+				else
-+					entity->new_weight = BFQ_MAX_WEIGHT;
-+			}
-+			entity->orig_weight = entity->new_weight;
-+			if (bfqq)
-+				bfqq->ioprio =
-+				  bfq_weight_to_ioprio(entity->orig_weight);
-+		}
-+
-+		if (bfqq && update_class_too)
-+			bfqq->ioprio_class = bfqq->new_ioprio_class;
-+
-+		/*
-+		 * Reset prio_changed only if the ioprio_class change
-+		 * is not pending any longer.
-+		 */
-+		if (!bfqq || bfqq->ioprio_class == bfqq->new_ioprio_class)
-+			entity->prio_changed = 0;
-+
-+		/*
-+		 * NOTE: here we may be changing the weight too early,
-+		 * this will cause unfairness.  The correct approach
-+		 * would have required additional complexity to defer
-+		 * weight changes to the proper time instants (i.e.,
-+		 * when entity->finish <= old_st->vtime).
-+		 */
-+		new_st = bfq_entity_service_tree(entity);
-+
-+		prev_weight = entity->weight;
-+		new_weight = entity->orig_weight *
-+			     (bfqq ? bfqq->wr_coeff : 1);
-+		/*
-+		 * If the weight of the entity changes and the entity is a
-+		 * queue, remove the entity from its old weight counter (if
-+		 * there is a counter associated with the entity).
-+		 */
-+		if (prev_weight != new_weight && bfqq) {
-+			bfq_log_bfqq(bfqq->bfqd, bfqq,
-+				     "weight changed %d %d(%d %d)",
-+				     prev_weight, new_weight,
-+				     entity->orig_weight,
-+				     bfqq->wr_coeff);
-+
-+			root = &bfqd->queue_weights_tree;
-+			__bfq_weights_tree_remove(bfqd, bfqq, root);
-+		}
-+		entity->weight = new_weight;
-+		/*
-+		 * Add the entity, if it is not a weight-raised queue, to the
-+		 * counter associated with its new weight.
-+		 */
-+		if (prev_weight != new_weight && bfqq && bfqq->wr_coeff == 1) {
-+			/* If we get here, root has been initialized. */
-+			bfq_weights_tree_add(bfqd, bfqq, root);
-+		}
-+
-+		new_st->wsum += entity->weight;
-+
-+		if (new_st != old_st) {
-+			BUG_ON(!update_class_too);
-+			entity->start = new_st->vtime;
-+		}
-+	}
-+
-+	return new_st;
-+}
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+static void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg);
-+#endif
-+
-+/**
-+ * bfq_bfqq_served - update the scheduler status after selection for
-+ *                   service.
-+ * @bfqq: the queue being served.
-+ * @served: bytes to transfer.
-+ *
-+ * NOTE: this can be optimized, as the timestamps of upper level entities
-+ * are synchronized every time a new bfqq is selected for service.  By now,
-+ * we keep it to better check consistency.
-+ */
-+static void bfq_bfqq_served(struct bfq_queue *bfqq, int served)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+	struct bfq_service_tree *st;
-+
-+	if (!bfqq->service_from_backlogged)
-+		bfqq->first_IO_time = jiffies;
-+
-+	if (bfqq->wr_coeff > 1)
-+		bfqq->service_from_wr += served;
-+
-+	bfqq->service_from_backlogged += served;
-+	for_each_entity(entity) {
-+		st = bfq_entity_service_tree(entity);
-+
-+		entity->service += served;
-+
-+		BUG_ON(st->wsum == 0);
-+
-+		st->vtime += bfq_delta(served, st->wsum);
-+		bfq_forget_idle(st);
-+	}
-+#ifndef BFQ_MQ
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	bfqg_stats_set_start_empty_time(bfqq_group(bfqq));
-+#endif
-+#endif
-+	st = bfq_entity_service_tree(&bfqq->entity);
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "bfqq_served %d secs, vtime %llu on %p",
-+		     served,  ((st->vtime>>10)*1000)>>12, st);
-+}
-+
-+/**
-+ * bfq_bfqq_charge_time - charge an amount of service equivalent to the length
-+ *			  of the time interval during which bfqq has been in
-+ *			  service.
-+ * @bfqd: the device
-+ * @bfqq: the queue that needs a service update.
-+ * @time_ms: the amount of time during which the queue has received service
-+ *
-+ * If a queue does not consume its budget fast enough, then providing
-+ * the queue with service fairness may impair throughput, more or less
-+ * severely. For this reason, queues that consume their budget slowly
-+ * are provided with time fairness instead of service fairness. This
-+ * goal is achieved through the BFQ scheduling engine, even if such an
-+ * engine works in the service, and not in the time domain. The trick
-+ * is charging these queues with an inflated amount of service, equal
-+ * to the amount of service that they would have received during their
-+ * service slot if they had been fast, i.e., if their requests had
-+ * been dispatched at a rate equal to the estimated peak rate.
-+ *
-+ * It is worth noting that time fairness can cause important
-+ * distortions in terms of bandwidth distribution, on devices with
-+ * internal queueing. The reason is that I/O requests dispatched
-+ * during the service slot of a queue may be served after that service
-+ * slot is finished, and may have a total processing time loosely
-+ * correlated with the duration of the service slot. This is
-+ * especially true for short service slots.
-+ */
-+static void bfq_bfqq_charge_time(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+				 unsigned long time_ms)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+	unsigned long timeout_ms = jiffies_to_msecs(bfq_timeout);
-+	unsigned long bounded_time_ms = min(time_ms, timeout_ms);
-+	int serv_to_charge_for_time =
-+		(bfqd->bfq_max_budget * bounded_time_ms) / timeout_ms;
-+	int tot_serv_to_charge = max(serv_to_charge_for_time, entity->service);
-+
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		     "%lu/%lu ms, %d/%d/%d/%d sectors",
-+		     time_ms, timeout_ms,
-+		     entity->service,
-+		     tot_serv_to_charge,
-+		     bfqd->bfq_max_budget,
-+		     entity->budget);
-+
-+	/* Increase budget to avoid inconsistencies */
-+	if (tot_serv_to_charge > entity->budget)
-+		entity->budget = tot_serv_to_charge;
-+
-+	bfq_bfqq_served(bfqq,
-+			max_t(int, 0, tot_serv_to_charge - entity->service));
-+}
-+
-+static void bfq_update_fin_time_enqueue(struct bfq_entity *entity,
-+					struct bfq_service_tree *st,
-+					bool backshifted)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+	struct bfq_sched_data *sd = entity->sched_data;
-+
-+	/*
-+	 * When this function is invoked, entity is not in any service
-+	 * tree, then it is safe to invoke next function with the last
-+	 * parameter set (see the comments on the function).
-+	 */
-+	BUG_ON(entity->tree);
-+	st = __bfq_entity_update_weight_prio(st, entity, true);
-+	bfq_calc_finish(entity, entity->budget);
-+
-+	/*
-+	 * If some queues enjoy backshifting for a while, then their
-+	 * (virtual) finish timestamps may happen to become lower and
-+	 * lower than the system virtual time.  In particular, if
-+	 * these queues often happen to be idle for short time
-+	 * periods, and during such time periods other queues with
-+	 * higher timestamps happen to be busy, then the backshifted
-+	 * timestamps of the former queues can become much lower than
-+	 * the system virtual time. In fact, to serve the queues with
-+	 * higher timestamps while the ones with lower timestamps are
-+	 * idle, the system virtual time may be pushed-up to much
-+	 * higher values than the finish timestamps of the idle
-+	 * queues. As a consequence, the finish timestamps of all new
-+	 * or newly activated queues may end up being much larger than
-+	 * those of lucky queues with backshifted timestamps. The
-+	 * latter queues may then monopolize the device for a lot of
-+	 * time. This would simply break service guarantees.
-+	 *
-+	 * To reduce this problem, push up a little bit the
-+	 * backshifted timestamps of the queue associated with this
-+	 * entity (only a queue can happen to have the backshifted
-+	 * flag set): just enough to let the finish timestamp of the
-+	 * queue be equal to the current value of the system virtual
-+	 * time. This may introduce a little unfairness among queues
-+	 * with backshifted timestamps, but it does not break
-+	 * worst-case fairness guarantees.
-+	 *
-+	 * As a special case, if bfqq is weight-raised, push up
-+	 * timestamps much less, to keep very low the probability that
-+	 * this push up causes the backshifted finish timestamps of
-+	 * weight-raised queues to become higher than the backshifted
-+	 * finish timestamps of non weight-raised queues.
-+	 */
-+	if (backshifted && bfq_gt(st->vtime, entity->finish)) {
-+		unsigned long delta = st->vtime - entity->finish;
-+
-+		if (bfqq)
-+			delta /= bfqq->wr_coeff;
-+
-+		entity->start += delta;
-+		entity->finish += delta;
-+
-+		if (bfqq) {
-+			bfq_log_bfqq(bfqq->bfqd, bfqq,
-+				     "new queue finish %llu",
-+				     ((entity->finish>>10)*1000)>>12);
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+		} else {
-+			struct bfq_group *bfqg =
-+				container_of(entity, struct bfq_group, entity);
-+
-+			bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+				     "new group finish %llu",
-+				     ((entity->finish>>10)*1000)>>12);
-+#endif
-+		}
-+	}
-+
-+	bfq_active_insert(st, entity);
-+
-+	if (bfqq) {
-+		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			"queue %seligible in st %p",
-+			     entity->start <= st->vtime ? "" : "non ", st);
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	} else {
-+		struct bfq_group *bfqg =
-+			container_of(entity, struct bfq_group, entity);
-+
-+		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+			"group %seligible in st %p",
-+			     entity->start <= st->vtime ? "" : "non ", st);
-+#endif
-+	}
-+	BUG_ON(RB_EMPTY_ROOT(&st->active));
-+	BUG_ON(&st->active != &sd->service_tree->active &&
-+	       &st->active != &(sd->service_tree+1)->active &&
-+	       &st->active != &(sd->service_tree+2)->active);
-+}
-+
-+/**
-+ * __bfq_activate_entity - handle activation of entity.
-+ * @entity: the entity being activated.
-+ * @non_blocking_wait_rq: true if entity was waiting for a request
-+ *
-+ * Called for a 'true' activation, i.e., if entity is not active and
-+ * one of its children receives a new request.
-+ *
-+ * Basically, this function updates the timestamps of entity and
-+ * inserts entity into its active tree, after possibly extracting it
-+ * from its idle tree.
-+ */
-+static void __bfq_activate_entity(struct bfq_entity *entity,
-+				  bool non_blocking_wait_rq)
-+{
-+	struct bfq_sched_data *sd = entity->sched_data;
-+	struct bfq_service_tree *st = bfq_entity_service_tree(entity);
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+	bool backshifted = false;
-+	unsigned long long min_vstart;
-+
-+	BUG_ON(!sd);
-+	BUG_ON(!st);
-+
-+	/* See comments on bfq_fqq_update_budg_for_activation */
-+	if (non_blocking_wait_rq && bfq_gt(st->vtime, entity->finish)) {
-+		backshifted = true;
-+		min_vstart = entity->finish;
-+	} else
-+		min_vstart = st->vtime;
-+
-+	if (entity->tree == &st->idle) {
-+		/*
-+		 * Must be on the idle tree, bfq_idle_extract() will
-+		 * check for that.
-+		 */
-+		bfq_idle_extract(st, entity);
-+		BUG_ON(entity->tree);
-+		entity->start = bfq_gt(min_vstart, entity->finish) ?
-+			min_vstart : entity->finish;
-+	} else {
-+		BUG_ON(entity->tree);
-+		/*
-+		 * The finish time of the entity may be invalid, and
-+		 * it is in the past for sure, otherwise the queue
-+		 * would have been on the idle tree.
-+		 */
-+		entity->start = min_vstart;
-+		st->wsum += entity->weight;
-+		/*
-+		 * entity is about to be inserted into a service tree,
-+		 * and then set in service: get a reference to make
-+		 * sure entity does not disappear until it is no
-+		 * longer in service or scheduled for service.
-+		 */
-+		bfq_get_entity(entity);
-+
-+		BUG_ON(entity->on_st && bfqq);
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+		if (entity->on_st && !bfqq) {
-+			struct bfq_group *bfqg =
-+				container_of(entity, struct bfq_group,
-+					     entity);
-+
-+			bfq_log_bfqg((struct bfq_data *)bfqg->bfqd,
-+				     bfqg,
-+				     "activate bug, class %d in_service %p",
-+				     bfq_class_idx(entity), sd->in_service_entity);
-+		}
-+#endif
-+		BUG_ON(entity->on_st && !bfqq);
-+		entity->on_st = true;
-+	}
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	if (!bfq_entity_to_bfqq(entity)) { /* bfq_group */
-+		struct bfq_group *bfqg =
-+			container_of(entity, struct bfq_group, entity);
-+		struct bfq_data *bfqd = bfqg->bfqd;
-+
-+		BUG_ON(!bfqd);
-+		if (!entity->in_groups_with_pending_reqs) {
-+			entity->in_groups_with_pending_reqs = true;
-+			bfqd->num_groups_with_pending_reqs++;
-+		}
-+		bfq_log_bfqg(bfqd, bfqg, "num_groups_with_pending_reqs %u",
-+			     bfqd->num_groups_with_pending_reqs);
-+	}
-+#endif
-+
-+	bfq_update_fin_time_enqueue(entity, st, backshifted);
-+}
-+
-+/**
-+ * __bfq_requeue_entity - handle requeueing or repositioning of an entity.
-+ * @entity: the entity being requeued or repositioned.
-+ *
-+ * Requeueing is needed if this entity stops being served, which
-+ * happens if a leaf descendant entity has expired. On the other hand,
-+ * repositioning is needed if the next_inservice_entity for the child
-+ * entity has changed. See the comments inside the function for
-+ * details.
-+ *
-+ * Basically, this function: 1) removes entity from its active tree if
-+ * present there, 2) updates the timestamps of entity and 3) inserts
-+ * entity back into its active tree (in the new, right position for
-+ * the new values of the timestamps).
-+ */
-+static void __bfq_requeue_entity(struct bfq_entity *entity)
-+{
-+	struct bfq_sched_data *sd = entity->sched_data;
-+	struct bfq_service_tree *st = bfq_entity_service_tree(entity);
-+
-+	BUG_ON(!sd);
-+	BUG_ON(!st);
-+
-+	BUG_ON(entity != sd->in_service_entity &&
-+	       entity->tree != &st->active);
-+
-+	if (entity == sd->in_service_entity) {
-+		/*
-+		 * We are requeueing the current in-service entity,
-+		 * which may have to be done for one of the following
-+		 * reasons:
-+		 * - entity represents the in-service queue, and the
-+		 *   in-service queue is being requeued after an
-+		 *   expiration;
-+		 * - entity represents a group, and its budget has
-+		 *   changed because one of its child entities has
-+		 *   just been either activated or requeued for some
-+		 *   reason; the timestamps of the entity need then to
-+		 *   be updated, and the entity needs to be enqueued
-+		 *   or repositioned accordingly.
-+		 *
-+		 * In particular, before requeueing, the start time of
-+		 * the entity must be moved forward to account for the
-+		 * service that the entity has received while in
-+		 * service. This is done by the next instructions. The
-+		 * finish time will then be updated according to this
-+		 * new value of the start time, and to the budget of
-+		 * the entity.
-+		 */
-+		bfq_calc_finish(entity, entity->service);
-+		entity->start = entity->finish;
-+		BUG_ON(entity->tree && entity->tree == &st->idle);
-+		BUG_ON(entity->tree && entity->tree != &st->active);
-+		/*
-+		 * In addition, if the entity had more than one child
-+		 * when set in service, then it was not extracted from
-+		 * the active tree. This implies that the position of
-+		 * the entity in the active tree may need to be
-+		 * changed now, because we have just updated the start
-+		 * time of the entity, and we will update its finish
-+		 * time in a moment (the requeueing is then, more
-+		 * precisely, a repositioning in this case). To
-+		 * implement this repositioning, we: 1) dequeue the
-+		 * entity here, 2) update the finish time and requeue
-+		 * the entity according to the new timestamps below.
-+		 */
-+		if (entity->tree)
-+			bfq_active_extract(st, entity);
-+	} else { /* The entity is already active, and not in service */
-+		/*
-+		 * In this case, this function gets called only if the
-+		 * next_in_service entity below this entity has
-+		 * changed, and this change has caused the budget of
-+		 * this entity to change, which, finally implies that
-+		 * the finish time of this entity must be
-+		 * updated. Such an update may cause the scheduling,
-+		 * i.e., the position in the active tree, of this
-+		 * entity to change. We handle this change by: 1)
-+		 * dequeueing the entity here, 2) updating the finish
-+		 * time and requeueing the entity according to the new
-+		 * timestamps below. This is the same approach as the
-+		 * non-extracted-entity sub-case above.
-+		 */
-+		bfq_active_extract(st, entity);
-+	}
-+
-+	bfq_update_fin_time_enqueue(entity, st, false);
-+}
-+
-+static void __bfq_activate_requeue_entity(struct bfq_entity *entity,
-+					  struct bfq_sched_data *sd,
-+					  bool non_blocking_wait_rq)
-+{
-+	struct bfq_service_tree *st = bfq_entity_service_tree(entity);
-+
-+	if (sd->in_service_entity == entity || entity->tree == &st->active)
-+		 /*
-+		  * in service or already queued on the active tree,
-+		  * requeue or reposition
-+		  */
-+		__bfq_requeue_entity(entity);
-+	else
-+		/*
-+		 * Not in service and not queued on its active tree:
-+		 * the activity is idle and this is a true activation.
-+		 */
-+		__bfq_activate_entity(entity, non_blocking_wait_rq);
-+}
-+
-+
-+/**
-+ * bfq_activate_requeue_entity - activate or requeue an entity representing a bfq_queue,
-+ *			 	 and activate, requeue or reposition all ancestors
-+ *			 	 for which such an update becomes necessary.
-+ * @entity: the entity to activate.
-+ * @non_blocking_wait_rq: true if this entity was waiting for a request
-+ * @requeue: true if this is a requeue, which implies that bfqq is
-+ *	     being expired; thus ALL its ancestors stop being served and must
-+ *	     therefore be requeued
-+ * @expiration: true if this function is being invoked in the expiration path
-+ *		of the in-service queue
-+ */
-+static void bfq_activate_requeue_entity(struct bfq_entity *entity,
-+					bool non_blocking_wait_rq,
-+					bool requeue, bool expiration)
-+{
-+	struct bfq_sched_data *sd;
-+
-+	for_each_entity(entity) {
-+		BUG_ON(!entity);
-+		sd = entity->sched_data;
-+		__bfq_activate_requeue_entity(entity, sd, non_blocking_wait_rq);
-+
-+		BUG_ON(RB_EMPTY_ROOT(&sd->service_tree->active) &&
-+		       RB_EMPTY_ROOT(&(sd->service_tree+1)->active) &&
-+		       RB_EMPTY_ROOT(&(sd->service_tree+2)->active));
-+
-+		if (!bfq_update_next_in_service(sd, entity, expiration) &&
-+		    !requeue) {
-+			BUG_ON(!sd->next_in_service);
-+			break;
-+		}
-+		BUG_ON(!sd->next_in_service);
-+	}
-+}
-+
-+/**
-+ * __bfq_deactivate_entity - update sched_data and service trees for
-+ * entity, so as to represent entity as inactive
-+ * @entity: the entity being deactivated.
-+ * @ins_into_idle_tree: if false, the entity will not be put into the
-+ *			idle tree.
-+ *
-+ * If necessary and allowed, puts entity into the idle tree. NOTE:
-+ * entity may be on no tree if in service.
-+ */
-+static bool __bfq_deactivate_entity(struct bfq_entity *entity,
-+				    bool ins_into_idle_tree)
-+{
-+	struct bfq_sched_data *sd = entity->sched_data;
-+	struct bfq_service_tree *st;
-+	bool is_in_service;
-+
-+	if (!entity->on_st) { /* entity never activated, or already inactive */
-+		BUG_ON(sd && entity == sd->in_service_entity);
-+		return false;
-+	}
-+
-+	/*
-+	 * If we get here, then entity is active, which implies that
-+	 * bfq_group_set_parent has already been invoked for the group
-+	 * represented by entity. Therefore, the field
-+	 * entity->sched_data has been set, and we can safely use it.
-+	 */
-+	st = bfq_entity_service_tree(entity);
-+	is_in_service = entity == sd->in_service_entity;
-+
-+	BUG_ON(is_in_service && entity->tree && entity->tree != &st->active);
-+
-+	bfq_calc_finish(entity, entity->service);
-+
-+	if (is_in_service) {
-+		sd->in_service_entity = NULL;
-+	} else
-+		/*
-+		 * Non in-service entity: nobody will take care of
-+		 * resetting its service counter on expiration. Do it
-+		 * now.
-+		 */
-+		entity->service = 0;
-+
-+	if (entity->tree == &st->active)
-+		bfq_active_extract(st, entity);
-+	else if (!is_in_service && entity->tree == &st->idle)
-+		bfq_idle_extract(st, entity);
-+	else if (entity->tree)
-+		BUG();
-+
-+	if (!ins_into_idle_tree || !bfq_gt(entity->finish, st->vtime))
-+		bfq_forget_entity(st, entity, is_in_service);
-+	else
-+		bfq_idle_insert(st, entity);
-+
-+	return true;
-+}
-+
-+/**
-+ * bfq_deactivate_entity - deactivate an entity representing a bfq_queue.
-+ * @entity: the entity to deactivate.
-+ * @ins_into_idle_tree: true if the entity can be put into the idle tree
-+ * @expiration: true if this function is being invoked in the expiration path
-+ *		of the in-service queue
-+ */
-+static void bfq_deactivate_entity(struct bfq_entity *entity,
-+				  bool ins_into_idle_tree,
-+				  bool expiration)
-+{
-+	struct bfq_sched_data *sd;
-+	struct bfq_entity *parent = NULL;
-+
-+	for_each_entity_safe(entity, parent) {
-+		sd = entity->sched_data;
-+
-+		BUG_ON(sd == NULL); /*
-+				     * It would mean that this is the
-+				     * root group.
-+				     */
-+
-+		BUG_ON(expiration && entity != sd->in_service_entity);
-+
-+		BUG_ON(entity != sd->in_service_entity &&
-+		       entity->tree ==
-+		       &bfq_entity_service_tree(entity)->active &&
-+		       !sd->next_in_service);
-+
-+		if (!__bfq_deactivate_entity(entity, ins_into_idle_tree)) {
-+			/*
-+			 * entity is not in any tree any more, so
-+			 * this deactivation is a no-op, and there is
-+			 * nothing to change for upper-level entities
-+			 * (in case of expiration, this can never
-+			 * happen).
-+			 */
-+			BUG_ON(expiration); /*
-+					     * entity cannot be already out of
-+					     * any tree
-+					     */
-+			return;
-+		}
-+
-+		if (sd->next_in_service == entity)
-+			/*
-+			 * entity was the next_in_service entity,
-+			 * then, since entity has just been
-+			 * deactivated, a new one must be found.
-+			 */
-+			bfq_update_next_in_service(sd, NULL, expiration);
-+
-+		if (sd->next_in_service || sd->in_service_entity) {
-+			/*
-+			 * The parent entity is still active, because
-+			 * either next_in_service or in_service_entity
-+			 * is not NULL. So, no further upwards
-+			 * deactivation must be performed.  Yet,
-+			 * next_in_service has changed.  Then the
-+			 * schedule does need to be updated upwards.
-+			 *
-+			 * NOTE If in_service_entity is not NULL, then
-+			 * next_in_service may happen to be NULL,
-+			 * although the parent entity is evidently
-+			 * active. This happens if 1) the entity
-+			 * pointed by in_service_entity is the only
-+			 * active entity in the parent entity, and 2)
-+			 * according to the definition of
-+			 * next_in_service, the in_service_entity
-+			 * cannot be considered as
-+			 * next_in_service. See the comments on the
-+			 * definition of next_in_service for details.
-+			 */
-+			BUG_ON(sd->next_in_service == entity);
-+			BUG_ON(sd->in_service_entity == entity);
-+			break;
-+		}
-+
-+		/*
-+		 * If we get here, then the parent is no more
-+		 * backlogged and we need to propagate the
-+		 * deactivation upwards. Thus let the loop go on.
-+		 */
-+
-+		/*
-+		 * Also let parent be queued into the idle tree on
-+		 * deactivation, to preserve service guarantees, and
-+		 * assuming that who invoked this function does not
-+		 * need parent entities too to be removed completely.
-+		 */
-+		ins_into_idle_tree = true;
-+	}
-+
-+	/*
-+	 * If the deactivation loop is fully executed, then there are
-+	 * no more entities to touch and next loop is not executed at
-+	 * all. Otherwise, requeue remaining entities if they are
-+	 * about to stop receiving service, or reposition them if this
-+	 * is not the case.
-+	 */
-+	entity = parent;
-+	for_each_entity(entity) {
-+		struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+
-+		/*
-+		 * Invoke __bfq_requeue_entity on entity, even if
-+		 * already active, to requeue/reposition it in the
-+		 * active tree (because sd->next_in_service has
-+		 * changed)
-+		 */
-+		__bfq_requeue_entity(entity);
-+
-+		sd = entity->sched_data;
-+		BUG_ON(expiration && sd->in_service_entity != entity);
-+
-+		if (bfqq)
-+			bfq_log_bfqq(bfqq->bfqd, bfqq,
-+				     "invoking udpdate_next for this queue");
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+		else {
-+			struct bfq_group *bfqg =
-+				container_of(entity,
-+					     struct bfq_group, entity);
-+
-+			bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+				     "invoking udpdate_next for this entity");
-+		}
-+#endif
-+		if (!bfq_update_next_in_service(sd, entity, expiration) &&
-+		    !expiration)
-+			/*
-+			 * next_in_service unchanged or not causing
-+			 * any change in entity->parent->sd, and no
-+			 * requeueing needed for expiration: stop
-+			 * here.
-+			 */
-+			break;
-+	}
-+}
-+
-+/**
-+ * bfq_calc_vtime_jump - compute the value to which the vtime should jump,
-+ *                       if needed, to have at least one entity eligible.
-+ * @st: the service tree to act upon.
-+ *
-+ * Assumes that st is not empty.
-+ */
-+static u64 bfq_calc_vtime_jump(struct bfq_service_tree *st)
-+{
-+	struct bfq_entity *root_entity = bfq_root_active_entity(&st->active);
-+
-+	if (bfq_gt(root_entity->min_start, st->vtime)) {
-+		struct bfq_queue *bfqq = bfq_entity_to_bfqq(root_entity);
-+
-+		if (bfqq)
-+			bfq_log_bfqq(bfqq->bfqd, bfqq,
-+				     "new value %llu",
-+				     ((root_entity->min_start>>10)*1000)>>12);
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+		else {
-+			struct bfq_group *bfqg =
-+				container_of(root_entity, struct bfq_group,
-+					     entity);
-+
-+			bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+				     "new value %llu",
-+				     ((root_entity->min_start>>10)*1000)>>12);
-+		}
-+#endif
-+		return root_entity->min_start;
-+	}
-+	return st->vtime;
-+}
-+
-+static void bfq_update_vtime(struct bfq_service_tree *st, u64 new_value)
-+{
-+	if (new_value > st->vtime) {
-+		st->vtime = new_value;
-+		bfq_forget_idle(st);
-+	}
-+}
-+
-+/**
-+ * bfq_first_active_entity - find the eligible entity with
-+ *                           the smallest finish time
-+ * @st: the service tree to select from.
-+ * @vtime: the system virtual to use as a reference for eligibility
-+ *
-+ * This function searches the first schedulable entity, starting from the
-+ * root of the tree and going on the left every time on this side there is
-+ * a subtree with at least one eligible (start >= vtime) entity. The path on
-+ * the right is followed only if a) the left subtree contains no eligible
-+ * entities and b) no eligible entity has been found yet.
-+ */
-+static struct bfq_entity *bfq_first_active_entity(struct bfq_service_tree *st,
-+						  u64 vtime)
-+{
-+	struct bfq_entity *entry, *first = NULL;
-+	struct rb_node *node = st->active.rb_node;
-+
-+	while (node) {
-+		entry = rb_entry(node, struct bfq_entity, rb_node);
-+left:
-+		if (!bfq_gt(entry->start, vtime))
-+			first = entry;
-+
-+		BUG_ON(bfq_gt(entry->min_start, vtime));
-+
-+		if (node->rb_left) {
-+			entry = rb_entry(node->rb_left,
-+					 struct bfq_entity, rb_node);
-+			if (!bfq_gt(entry->min_start, vtime)) {
-+				node = node->rb_left;
-+				goto left;
-+			}
-+		}
-+		if (first)
-+			break;
-+		node = node->rb_right;
-+	}
-+
-+	BUG_ON(!first && !RB_EMPTY_ROOT(&st->active));
-+	return first;
-+}
-+
-+/**
-+ * __bfq_lookup_next_entity - return the first eligible entity in @st.
-+ * @st: the service tree.
-+ *
-+ * If there is no in-service entity for the sched_data st belongs to,
-+ * then return the entity that will be set in service if:
-+ * 1) the parent entity this st belongs to is set in service;
-+ * 2) no entity belonging to such parent entity undergoes a state change
-+ * that would influence the timestamps of the entity (e.g., becomes idle,
-+ * becomes backlogged, changes its budget, ...).
-+ *
-+ * In this first case, update the virtual time in @st too (see the
-+ * comments on this update inside the function).
-+ *
-+ * In constrast, if there is an in-service entity, then return the
-+ * entity that would be set in service if not only the above
-+ * conditions, but also the next one held true: the currently
-+ * in-service entity, on expiration,
-+ * 1) gets a finish time equal to the current one, or
-+ * 2) is not eligible any more, or
-+ * 3) is idle.
-+ */
-+static struct bfq_entity *
-+__bfq_lookup_next_entity(struct bfq_service_tree *st, bool in_service)
-+{
-+	struct bfq_entity *entity;
-+	u64 new_vtime;
-+	struct bfq_queue *bfqq;
-+
-+	if (RB_EMPTY_ROOT(&st->active))
-+		return NULL;
-+
-+	/*
-+	 * Get the value of the system virtual time for which at
-+	 * least one entity is eligible.
-+	 */
-+	new_vtime = bfq_calc_vtime_jump(st);
-+
-+	/*
-+	 * If there is no in-service entity for the sched_data this
-+	 * active tree belongs to, then push the system virtual time
-+	 * up to the value that guarantees that at least one entity is
-+	 * eligible. If, instead, there is an in-service entity, then
-+	 * do not make any such update, because there is already an
-+	 * eligible entity, namely the in-service one (even if the
-+	 * entity is not on st, because it was extracted when set in
-+	 * service).
-+	 */
-+	if (!in_service)
-+		bfq_update_vtime(st, new_vtime);
-+
-+	entity = bfq_first_active_entity(st, new_vtime);
-+	BUG_ON(bfq_gt(entity->start, new_vtime));
-+
-+	/* Log some information */
-+	bfqq = bfq_entity_to_bfqq(entity);
-+	if (bfqq)
-+		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			     "start %llu vtime %llu st %p",
-+			     ((entity->start>>10)*1000)>>12,
-+			     ((new_vtime>>10)*1000)>>12, st);
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	else {
-+		struct bfq_group *bfqg =
-+			container_of(entity, struct bfq_group, entity);
-+
-+		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+			     "start %llu vtime %llu (%llu) st %p",
-+			     ((entity->start>>10)*1000)>>12,
-+			     ((st->vtime>>10)*1000)>>12,
-+			     ((new_vtime>>10)*1000)>>12, st);
-+	}
-+#endif
-+
-+	BUG_ON(!entity);
-+
-+	return entity;
-+}
-+
-+/**
-+ * bfq_lookup_next_entity - return the first eligible entity in @sd.
-+ * @sd: the sched_data.
-+ * @expiration: true if we are on the expiration path of the in-service queue
-+ *
-+ * This function is invoked when there has been a change in the trees
-+ * for sd, and we need to know what is the new next entity to serve
-+ * after this change.
-+ */
-+static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd,
-+						 bool expiration)
-+{
-+	struct bfq_service_tree *st = sd->service_tree;
-+	struct bfq_service_tree *idle_class_st = st + (BFQ_IOPRIO_CLASSES - 1);
-+	struct bfq_entity *entity = NULL;
-+	struct bfq_queue *bfqq;
-+	int class_idx = 0;
-+
-+	BUG_ON(!sd);
-+	BUG_ON(!st);
-+	/*
-+	 * Choose from idle class, if needed to guarantee a minimum
-+	 * bandwidth to this class (and if there is some active entity
-+	 * in idle class). This should also mitigate
-+	 * priority-inversion problems in case a low priority task is
-+	 * holding file system resources.
-+	 */
-+	if (time_is_before_jiffies(sd->bfq_class_idle_last_service +
-+				   BFQ_CL_IDLE_TIMEOUT)) {
-+		if (!RB_EMPTY_ROOT(&idle_class_st->active))
-+			class_idx = BFQ_IOPRIO_CLASSES - 1;
-+		/* About to be served if backlogged, or not yet backlogged */
-+		sd->bfq_class_idle_last_service = jiffies;
-+	}
-+
-+	/*
-+	 * Find the next entity to serve for the highest-priority
-+	 * class, unless the idle class needs to be served.
-+	 */
-+	for (; class_idx < BFQ_IOPRIO_CLASSES; class_idx++) {
-+		/*
-+		 * If expiration is true, then bfq_lookup_next_entity
-+		 * is being invoked as a part of the expiration path
-+		 * of the in-service queue. In this case, even if
-+		 * sd->in_service_entity is not NULL,
-+		 * sd->in_service_entiy at this point is actually not
-+		 * in service any more, and, if needed, has already
-+		 * been properly queued or requeued into the right
-+		 * tree. The reason why sd->in_service_entity is still
-+		 * not NULL here, even if expiration is true, is that
-+		 * sd->in_service_entiy is reset as a last step in the
-+		 * expiration path. So, if expiration is true, tell
-+		 * __bfq_lookup_next_entity that there is no
-+		 * sd->in_service_entity.
-+		 */
-+		entity = __bfq_lookup_next_entity(st + class_idx,
-+						  sd->in_service_entity &&
-+						  !expiration);
-+
-+		if (entity)
-+			break;
-+	}
-+
-+	BUG_ON(!entity &&
-+	       (!RB_EMPTY_ROOT(&st->active) || !RB_EMPTY_ROOT(&(st+1)->active) ||
-+		!RB_EMPTY_ROOT(&(st+2)->active)));
-+
-+	if (!entity)
-+		return NULL;
-+
-+	/* Log some information */
-+	bfqq = bfq_entity_to_bfqq(entity);
-+	if (bfqq)
-+		bfq_log_bfqq(bfqq->bfqd, bfqq, "chosen from st %p %d",
-+			     st + class_idx, class_idx);
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	else {
-+		struct bfq_group *bfqg =
-+			container_of(entity, struct bfq_group, entity);
-+
-+		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+			     "chosen from st %p %d",
-+			     st + class_idx, class_idx);
-+	}
-+#endif
-+
-+	return entity;
-+}
-+
-+static bool next_queue_may_preempt(struct bfq_data *bfqd)
-+{
-+	struct bfq_sched_data *sd = &bfqd->root_group->sched_data;
-+
-+	return sd->next_in_service != sd->in_service_entity;
-+}
-+
-+/*
-+ * Get next queue for service.
-+ */
-+static struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd)
-+{
-+	struct bfq_entity *entity = NULL;
-+	struct bfq_sched_data *sd;
-+	struct bfq_queue *bfqq;
-+
-+	BUG_ON(bfqd->in_service_queue);
-+
-+	if (bfq_tot_busy_queues(bfqd) == 0)
-+		return NULL;
-+
-+	/*
-+	 * Traverse the path from the root to the leaf entity to
-+	 * serve. Set in service all the entities visited along the
-+	 * way.
-+	 */
-+	sd = &bfqd->root_group->sched_data;
-+	for (; sd ; sd = entity->my_sched_data) {
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+		if (entity) {
-+			struct bfq_group *bfqg =
-+				container_of(entity, struct bfq_group, entity);
-+
-+			bfq_log_bfqg(bfqd, bfqg,
-+				     "lookup in this group");
-+			if (!sd->next_in_service)
-+				pr_crit("lookup in this group");
-+		} else {
-+			bfq_log_bfqg(bfqd, bfqd->root_group,
-+				     "lookup in root group");
-+			if (!sd->next_in_service)
-+				pr_crit("lookup in root group");
-+		}
-+#endif
-+
-+		BUG_ON(!sd->next_in_service);
-+
-+		/*
-+		 * WARNING. We are about to set the in-service entity
-+		 * to sd->next_in_service, i.e., to the (cached) value
-+		 * returned by bfq_lookup_next_entity(sd) the last
-+		 * time it was invoked, i.e., the last time when the
-+		 * service order in sd changed as a consequence of the
-+		 * activation or deactivation of an entity. In this
-+		 * respect, if we execute bfq_lookup_next_entity(sd)
-+		 * in this very moment, it may, although with low
-+		 * probability, yield a different entity than that
-+		 * pointed to by sd->next_in_service. This rare event
-+		 * happens in case there was no CLASS_IDLE entity to
-+		 * serve for sd when bfq_lookup_next_entity(sd) was
-+		 * invoked for the last time, while there is now one
-+		 * such entity.
-+		 *
-+		 * If the above event happens, then the scheduling of
-+		 * such entity in CLASS_IDLE is postponed until the
-+		 * service of the sd->next_in_service entity
-+		 * finishes. In fact, when the latter is expired,
-+		 * bfq_lookup_next_entity(sd) gets called again,
-+		 * exactly to update sd->next_in_service.
-+		 */
-+
-+		/* Make next_in_service entity become in_service_entity */
-+		entity = sd->next_in_service;
-+		sd->in_service_entity = entity;
-+
-+		/*
-+		 * If entity is no longer a candidate for next
-+		 * service, then it must be extracted from its active
-+		 * tree, so as to make sure that it won't be
-+		 * considered when computing next_in_service. See the
-+		 * comments on the function
-+		 * bfq_no_longer_next_in_service() for details.
-+		 */
-+		if (bfq_no_longer_next_in_service(entity))
-+			bfq_active_extract(bfq_entity_service_tree(entity),
-+					   entity);
-+
-+		/*
-+		 * Even if entity is not to be extracted according to
-+		 * the above check, a descendant entity may get
-+		 * extracted in one of the next iterations of this
-+		 * loop. Such an event could cause a change in
-+		 * next_in_service for the level of the descendant
-+		 * entity, and thus possibly back to this level.
-+		 *
-+		 * However, we cannot perform the resulting needed
-+		 * update of next_in_service for this level before the
-+		 * end of the whole loop, because, to know which is
-+		 * the correct next-to-serve candidate entity for each
-+		 * level, we need first to find the leaf entity to set
-+		 * in service. In fact, only after we know which is
-+		 * the next-to-serve leaf entity, we can discover
-+		 * whether the parent entity of the leaf entity
-+		 * becomes the next-to-serve, and so on.
-+		 */
-+
-+		/* Log some information */
-+		bfqq = bfq_entity_to_bfqq(entity);
-+		if (bfqq)
-+			bfq_log_bfqq(bfqd, bfqq,
-+			     "this queue, finish %llu",
-+				(((entity->finish>>10)*1000)>>10)>>2);
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+		else {
-+			struct bfq_group *bfqg =
-+				container_of(entity, struct bfq_group, entity);
-+
-+			bfq_log_bfqg(bfqd, bfqg,
-+			     "this entity, finish %llu",
-+				(((entity->finish>>10)*1000)>>10)>>2);
-+		}
-+#endif
-+
-+	}
-+
-+	BUG_ON(!entity);
-+	bfqq = bfq_entity_to_bfqq(entity);
-+	BUG_ON(!bfqq);
-+
-+	/*
-+	 * We can finally update all next-to-serve entities along the
-+	 * path from the leaf entity just set in service to the root.
-+	 */
-+	for_each_entity(entity) {
-+		struct bfq_sched_data *sd = entity->sched_data;
-+
-+		if (!bfq_update_next_in_service(sd, NULL, false))
-+			break;
-+	}
-+
-+	return bfqq;
-+}
-+
-+static void __bfq_bfqd_reset_in_service(struct bfq_data *bfqd)
-+{
-+	struct bfq_queue *in_serv_bfqq = bfqd->in_service_queue;
-+	struct bfq_entity *in_serv_entity = &in_serv_bfqq->entity;
-+	struct bfq_entity *entity = in_serv_entity;
-+
-+#ifndef BFQ_MQ
-+	if (bfqd->in_service_bic) {
-+		put_io_context(bfqd->in_service_bic->icq.ioc);
-+		bfqd->in_service_bic = NULL;
-+	}
-+#endif
-+
-+	bfq_clear_bfqq_wait_request(in_serv_bfqq);
-+	hrtimer_try_to_cancel(&bfqd->idle_slice_timer);
-+	bfqd->in_service_queue = NULL;
-+
-+	/*
-+	 * When this function is called, all in-service entities have
-+	 * been properly deactivated or requeued, so we can safely
-+	 * execute the final step: reset in_service_entity along the
-+	 * path from entity to the root.
-+	 */
-+	for_each_entity(entity)
-+		entity->sched_data->in_service_entity = NULL;
-+
-+	/*
-+	 * in_serv_entity is no longer in service, so, if it is in no
-+	 * service tree either, then release the service reference to
-+	 * the queue it represents (taken with bfq_get_entity).
-+	 */
-+	if (!in_serv_entity->on_st)
-+		bfq_put_queue(in_serv_bfqq);
-+}
-+
-+static void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+				bool ins_into_idle_tree, bool expiration)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+
-+	bfq_deactivate_entity(entity, ins_into_idle_tree, expiration);
-+}
-+
-+static void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+	struct bfq_service_tree *st = bfq_entity_service_tree(entity);
-+
-+	BUG_ON(bfqq == bfqd->in_service_queue);
-+	BUG_ON(entity->tree != &st->active && entity->tree != &st->idle &&
-+	       entity->on_st);
-+
-+	bfq_activate_requeue_entity(entity, bfq_bfqq_non_blocking_wait_rq(bfqq),
-+				    false, false);
-+	bfq_clear_bfqq_non_blocking_wait_rq(bfqq);
-+}
-+
-+static void bfq_requeue_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+			     bool expiration)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+
-+	bfq_activate_requeue_entity(entity, false,
-+				    bfqq == bfqd->in_service_queue, expiration);
-+}
-+
-+static void bfqg_stats_update_dequeue(struct bfq_group *bfqg);
-+
-+/*
-+ * Called when the bfqq no longer has requests pending, remove it from
-+ * the service tree. As a special case, it can be invoked during an
-+ * expiration.
-+ */
-+static void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+			      bool expiration)
-+{
-+	BUG_ON(!bfq_bfqq_busy(bfqq));
-+	BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list));
-+
-+	bfq_log_bfqq(bfqd, bfqq, "del from busy");
-+
-+	bfq_clear_bfqq_busy(bfqq);
-+
-+	BUG_ON(bfq_tot_busy_queues(bfqd) == 0);
-+	bfqd->busy_queues[bfqq->ioprio_class - 1]--;
-+
-+	if (bfqq->wr_coeff > 1) {
-+		bfqd->wr_busy_queues--;
-+		BUG_ON(bfqd->wr_busy_queues < 0);
-+	}
-+
-+	bfqg_stats_update_dequeue(bfqq_group(bfqq));
-+
-+	BUG_ON(bfqq->entity.budget < 0);
-+
-+	bfq_deactivate_bfqq(bfqd, bfqq, true, expiration);
-+	if (!bfqq->dispatched)
-+		bfq_weights_tree_remove(bfqd, bfqq);
-+}
-+
-+/*
-+ * Called when an inactive queue receives a new request.
-+ */
-+static void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	BUG_ON(bfq_bfqq_busy(bfqq));
-+	BUG_ON(bfqq == bfqd->in_service_queue);
-+
-+	bfq_log_bfqq(bfqd, bfqq, "add to busy");
-+
-+	bfq_activate_bfqq(bfqd, bfqq);
-+
-+	bfq_mark_bfqq_busy(bfqq);
-+	bfqd->busy_queues[bfqq->ioprio_class - 1]++;
-+
-+	if (!bfqq->dispatched)
-+		if (bfqq->wr_coeff == 1)
-+			bfq_weights_tree_add(bfqd, bfqq,
-+					     &bfqd->queue_weights_tree);
-+
-+	if (bfqq->wr_coeff > 1) {
-+		bfqd->wr_busy_queues++;
-+		BUG_ON(bfqd->wr_busy_queues > bfq_tot_busy_queues(bfqd));
-+	}
-+
-+}
-diff --git a/block/bfq-sq-iosched.c b/block/bfq-sq-iosched.c
-new file mode 100644
-index 000000000000..6da94eef0cf1
---- /dev/null
-+++ b/block/bfq-sq-iosched.c
-@@ -0,0 +1,5957 @@
-+/*
-+ * Budget Fair Queueing (BFQ) I/O scheduler.
-+ *
-+ * Based on ideas and code from CFQ:
-+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
-+ *
-+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
-+ *		      Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2017 Paolo Valente <paolo.valente@linaro.org>
-+ *
-+ * Licensed under the GPL-2 as detailed in the accompanying COPYING.BFQ
-+ * file.
-+ *
-+ * BFQ is a proportional-share I/O scheduler, with some extra
-+ * low-latency capabilities. BFQ also supports full hierarchical
-+ * scheduling through cgroups. Next paragraphs provide an introduction
-+ * on BFQ inner workings. Details on BFQ benefits and usage can be
-+ * found in Documentation/block/bfq-iosched.txt.
-+ *
-+ * BFQ is a proportional-share storage-I/O scheduling algorithm based
-+ * on the slice-by-slice service scheme of CFQ. But BFQ assigns
-+ * budgets, measured in number of sectors, to processes instead of
-+ * time slices. The device is not granted to the in-service process
-+ * for a given time slice, but until it has exhausted its assigned
-+ * budget. This change from the time to the service domain enables BFQ
-+ * to distribute the device throughput among processes as desired,
-+ * without any distortion due to throughput fluctuations, or to device
-+ * internal queueing. BFQ uses an ad hoc internal scheduler, called
-+ * B-WF2Q+, to schedule processes according to their budgets. More
-+ * precisely, BFQ schedules queues associated with processes. Thanks to
-+ * the accurate policy of B-WF2Q+, BFQ can afford to assign high
-+ * budgets to I/O-bound processes issuing sequential requests (to
-+ * boost the throughput), and yet guarantee a low latency to
-+ * interactive and soft real-time applications.
-+ *
-+ * In particular, BFQ schedules I/O so as to achieve the latter goal--
-+ * low latency for interactive and soft real-time applications--if the
-+ * low_latency parameter is set (default configuration). To this
-+ * purpose, BFQ constantly tries to detect whether the I/O requests in
-+ * a bfq_queue come from an interactive or a soft real-time
-+ * application. For brevity, in these cases, the queue is said to be
-+ * interactive or soft real-time. In both cases, BFQ privileges the
-+ * service of the queue, over that of non-interactive and
-+ * non-soft-real-time queues. This privileging is performed, mainly,
-+ * by raising the weight of the queue. So, for brevity, we call just
-+ * weight-raising periods the time periods during which a queue is
-+ * privileged, because deemed interactive or soft real-time.
-+ *
-+ * The detection of soft real-time queues/applications is described in
-+ * detail in the comments on the function
-+ * bfq_bfqq_softrt_next_start. On the other hand, the detection of an
-+ * interactive queue works as follows: a queue is deemed interactive
-+ * if it is constantly non empty only for a limited time interval,
-+ * after which it does become empty. The queue may be deemed
-+ * interactive again (for a limited time), if it restarts being
-+ * constantly non empty, provided that this happens only after the
-+ * queue has remained empty for a given minimum idle time.
-+ *
-+ * By default, BFQ computes automatically the above maximum time
-+ * interval, i.e., the time interval after which a constantly
-+ * non-empty queue stops being deemed interactive. Since a queue is
-+ * weight-raised while it is deemed interactive, this maximum time
-+ * interval happens to coincide with the (maximum) duration of the
-+ * weight-raising for interactive queues.
-+ *
-+ * NOTE: if the main or only goal, with a given device, is to achieve
-+ * the maximum-possible throughput at all times, then do switch off
-+ * all low-latency heuristics for that device, by setting low_latency
-+ * to 0.
-+ *
-+ * BFQ is described in [1], where also a reference to the initial,
-+ * more theoretical paper on BFQ can be found. The interested reader
-+ * can find in the latter paper full details on the main algorithm, as
-+ * well as formulas of the guarantees and formal proofs of all the
-+ * properties.  With respect to the version of BFQ presented in these
-+ * papers, this implementation adds a few more heuristics, such as the
-+ * one that guarantees a low latency to soft real-time applications,
-+ * and a hierarchical extension based on H-WF2Q+.
-+ *
-+ * B-WF2Q+ is based on WF2Q+, that is described in [2], together with
-+ * H-WF2Q+, while the augmented tree used to implement B-WF2Q+ with O(log N)
-+ * complexity derives from the one introduced with EEVDF in [3].
-+ *
-+ * [1] P. Valente, A. Avanzini, "Evolution of the BFQ Storage I/O
-+ *   Scheduler", Proceedings of the First Workshop on Mobile System
-+ *   Technologies (MST-2015), May 2015.
-+ *   http://algogroup.unimore.it/people/paolo/disk_sched/mst-2015.pdf
-+ *
-+ * http://algogroup.unimo.it/people/paolo/disk_sched/bf1-v1-suite-results.pdf
-+ *
-+ * [2] Jon C.R. Bennett and H. Zhang, ``Hierarchical Packet Fair Queueing
-+ *     Algorithms,'' IEEE/ACM Transactions on Networking, 5(5):675-689,
-+ *     Oct 1997.
-+ *
-+ * http://www.cs.cmu.edu/~hzhang/papers/TON-97-Oct.ps.gz
-+ *
-+ * [3] I. Stoica and H. Abdel-Wahab, ``Earliest Eligible Virtual Deadline
-+ *     First: A Flexible and Accurate Mechanism for Proportional Share
-+ *     Resource Allocation,'' technical report.
-+ *
-+ * http://www.cs.berkeley.edu/~istoica/papers/eevdf-tr-95.pdf
-+ */
-+#include <linux/module.h>
-+#include <linux/slab.h>
-+#include <linux/blkdev.h>
-+#include <linux/cgroup.h>
-+#include <linux/elevator.h>
-+#include <linux/jiffies.h>
-+#include <linux/rbtree.h>
-+#include <linux/ioprio.h>
-+#include "blk.h"
-+#include "bfq.h"
-+#include "blk-wbt.h"
-+
-+/* Expiration time of sync (0) and async (1) requests, in ns. */
-+static const u64 bfq_fifo_expire[2] = { NSEC_PER_SEC / 4, NSEC_PER_SEC / 8 };
-+
-+/* Maximum backwards seek, in KiB. */
-+static const int bfq_back_max = (16 * 1024);
-+
-+/* Penalty of a backwards seek, in number of sectors. */
-+static const int bfq_back_penalty = 2;
-+
-+/* Idling period duration, in ns. */
-+static u32 bfq_slice_idle = (NSEC_PER_SEC / 125);
-+
-+/* Minimum number of assigned budgets for which stats are safe to compute. */
-+static const int bfq_stats_min_budgets = 194;
-+
-+/* Default maximum budget values, in sectors and number of requests. */
-+static const int bfq_default_max_budget = (16 * 1024);
-+
-+/*
-+ * When a sync request is dispatched, the queue that contains that
-+ * request, and all the ancestor entities of that queue, are charged
-+ * with the number of sectors of the request. In constrast, if the
-+ * request is async, then the queue and its ancestor entities are
-+ * charged with the number of sectors of the request, multiplied by
-+ * the factor below. This throttles the bandwidth for async I/O,
-+ * w.r.t. to sync I/O, and it is done to counter the tendency of async
-+ * writes to steal I/O throughput to reads.
-+ *
-+ * The current value of this parameter is the result of a tuning with
-+ * several hardware and software configurations. We tried to find the
-+ * lowest value for which writes do not cause noticeable problems to
-+ * reads. In fact, the lower this parameter, the stabler I/O control,
-+ * in the following respect.  The lower this parameter is, the less
-+ * the bandwidth enjoyed by a group decreases
-+ * - when the group does writes, w.r.t. to when it does reads;
-+ * - when other groups do reads, w.r.t. to when they do writes.
-+ */
-+static const int bfq_async_charge_factor = 3;
-+
-+/* Default timeout values, in jiffies, approximating CFQ defaults. */
-+static const int bfq_timeout = (HZ / 8);
-+
-+/*
-+ * Time limit for merging (see comments in bfq_setup_cooperator). Set
-+ * to the slowest value that, in our tests, proved to be effective in
-+ * removing false positives, while not causing true positives to miss
-+ * queue merging.
-+ *
-+ * As can be deduced from the low time limit below, queue merging, if
-+ * successful, happens at the very beggining of the I/O of the involved
-+ * cooperating processes, as a consequence of the arrival of the very
-+ * first requests from each cooperator.  After that, there is very
-+ * little chance to find cooperators.
-+ */
-+static const unsigned long bfq_merge_time_limit = HZ/10;
-+
-+#define MAX_LENGTH_REASON_NAME 25
-+
-+static const char reason_name[][MAX_LENGTH_REASON_NAME] = {"TOO_IDLE",
-+"BUDGET_TIMEOUT", "BUDGET_EXHAUSTED", "NO_MORE_REQUESTS",
-+"PREEMPTED"};
-+
-+static struct kmem_cache *bfq_pool;
-+
-+/* Below this threshold (in ns), we consider thinktime immediate. */
-+#define BFQ_MIN_TT		(2 * NSEC_PER_MSEC)
-+
-+/* hw_tag detection: parallel requests threshold and min samples needed. */
-+#define BFQ_HW_QUEUE_THRESHOLD	3
-+#define BFQ_HW_QUEUE_SAMPLES	32
-+
-+#define BFQQ_SEEK_THR		(sector_t)(8 * 100)
-+#define BFQQ_SECT_THR_NONROT	(sector_t)(2 * 32)
-+#define BFQ_RQ_SEEKY(bfqd, last_pos, rq) \
-+				(get_sdist(last_pos, rq) >  \
-+				 BFQQ_SEEK_THR && \
-+				 (!blk_queue_nonrot(bfqd->queue) || \
-+				  blk_rq_sectors(rq) < BFQQ_SECT_THR_NONROT))
-+#define BFQQ_CLOSE_THR		(sector_t)(8 * 1024)
-+#define BFQQ_SEEKY(bfqq)	(hweight32(bfqq->seek_history) > 19)
-+
-+/* Min number of samples required to perform peak-rate update */
-+#define BFQ_RATE_MIN_SAMPLES	32
-+/* Min observation time interval required to perform a peak-rate update (ns) */
-+#define BFQ_RATE_MIN_INTERVAL	(300*NSEC_PER_MSEC)
-+/* Target observation time interval for a peak-rate update (ns) */
-+#define BFQ_RATE_REF_INTERVAL	NSEC_PER_SEC
-+
-+/*
-+ * Shift used for peak-rate fixed precision calculations.
-+ * With
-+ * - the current shift: 16 positions
-+ * - the current type used to store rate: u32
-+ * - the current unit of measure for rate: [sectors/usec], or, more precisely,
-+ *   [(sectors/usec) / 2^BFQ_RATE_SHIFT] to take into account the shift,
-+ * the range of rates that can be stored is
-+ * [1 / 2^BFQ_RATE_SHIFT, 2^(32 - BFQ_RATE_SHIFT)] sectors/usec =
-+ * [1 / 2^16, 2^16] sectors/usec = [15e-6, 65536] sectors/usec =
-+ * [15, 65G] sectors/sec
-+ * Which, assuming a sector size of 512B, corresponds to a range of
-+ * [7.5K, 33T] B/sec
-+ */
-+#define BFQ_RATE_SHIFT		16
-+
-+/*
-+ * When configured for computing the duration of the weight-raising
-+ * for interactive queues automatically (see the comments at the
-+ * beginning of this file), BFQ does it using the following formula:
-+ * duration = (ref_rate / r) * ref_wr_duration,
-+ * where r is the peak rate of the device, and ref_rate and
-+ * ref_wr_duration are two reference parameters.  In particular,
-+ * ref_rate is the peak rate of the reference storage device (see
-+ * below), and ref_wr_duration is about the maximum time needed, with
-+ * BFQ and while reading two files in parallel, to load typical large
-+ * applications on the reference device (see the comments on
-+ * max_service_from_wr below, for more details on how ref_wr_duration
-+ * is obtained).  In practice, the slower/faster the device at hand
-+ * is, the more/less it takes to load applications with respect to the
-+ * reference device.  Accordingly, the longer/shorter BFQ grants
-+ * weight raising to interactive applications.
-+ *
-+ * BFQ uses two different reference pairs (ref_rate, ref_wr_duration),
-+ * depending on whether the device is rotational or non-rotational.
-+ *
-+ * In the following definitions, ref_rate[0] and ref_wr_duration[0]
-+ * are the reference values for a rotational device, whereas
-+ * ref_rate[1] and ref_wr_duration[1] are the reference values for a
-+ * non-rotational device. The reference rates are not the actual peak
-+ * rates of the devices used as a reference, but slightly lower
-+ * values. The reason for using slightly lower values is that the
-+ * peak-rate estimator tends to yield slightly lower values than the
-+ * actual peak rate (it can yield the actual peak rate only if there
-+ * is only one process doing I/O, and the process does sequential
-+ * I/O).
-+ *
-+ * The reference peak rates are measured in sectors/usec, left-shifted
-+ * by BFQ_RATE_SHIFT.
-+ */
-+static int ref_rate[2] = {14000, 33000};
-+/*
-+ * To improve readability, a conversion function is used to initialize
-+ * the following array, which entails that the array can be
-+ * initialized only in a function.
-+ */
-+static int ref_wr_duration[2];
-+
-+/*
-+ * BFQ uses the above-detailed, time-based weight-raising mechanism to
-+ * privilege interactive tasks. This mechanism is vulnerable to the
-+ * following false positives: I/O-bound applications that will go on
-+ * doing I/O for much longer than the duration of weight
-+ * raising. These applications have basically no benefit from being
-+ * weight-raised at the beginning of their I/O. On the opposite end,
-+ * while being weight-raised, these applications
-+ * a) unjustly steal throughput to applications that may actually need
-+ * low latency;
-+ * b) make BFQ uselessly perform device idling; device idling results
-+ * in loss of device throughput with most flash-based storage, and may
-+ * increase latencies when used purposelessly.
-+ *
-+ * BFQ tries to reduce these problems, by adopting the following
-+ * countermeasure. To introduce this countermeasure, we need first to
-+ * finish explaining how the duration of weight-raising for
-+ * interactive tasks is computed.
-+ *
-+ * For a bfq_queue deemed as interactive, the duration of weight
-+ * raising is dynamically adjusted, as a function of the estimated
-+ * peak rate of the device, so as to be equal to the time needed to
-+ * execute the 'largest' interactive task we benchmarked so far. By
-+ * largest task, we mean the task for which each involved process has
-+ * to do more I/O than for any of the other tasks we benchmarked. This
-+ * reference interactive task is the start-up of LibreOffice Writer,
-+ * and in this task each process/bfq_queue needs to have at most ~110K
-+ * sectors transfered.
-+ *
-+ * This last piece of information enables BFQ to reduce the actual
-+ * duration of weight-raising for at least one class of I/O-bound
-+ * applications: those doing sequential or quasi-sequential I/O. An
-+ * example is file copy. In fact, once started, the main I/O-bound
-+ * processes of these applications usually consume the above 110K
-+ * sectors in much less time than the processes of an application that
-+ * is starting, because these I/O-bound processes will greedily devote
-+ * almost all their CPU cycles only to their target,
-+ * throughput-friendly I/O operations. This is even more true if BFQ
-+ * happens to be underestimating the device peak rate, and thus
-+ * overestimating the duration of weight raising. But, according to
-+ * our measurements, once transferred 110K sectors, these processes
-+ * have no right to be weight-raised any longer.
-+ *
-+ * Basing on the last consideration, BFQ ends weight-raising for a
-+ * bfq_queue if the latter happens to have received an amount of
-+ * service at least equal to the following constant. The constant is
-+ * set to slightly more than 110K, to have a minimum safety margin.
-+ *
-+ * This early ending of weight-raising reduces the amount of time
-+ * during which interactive false positives cause the two problems
-+ * described at the beginning of these comments.
-+ */
-+static const unsigned long max_service_from_wr = 120000;
-+
-+#define BFQ_SERVICE_TREE_INIT	((struct bfq_service_tree)		\
-+				{ RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 })
-+
-+#define RQ_BIC(rq)		icq_to_bic((rq)->elv.priv[0])
-+#define RQ_BFQQ(rq)		((rq)->elv.priv[1])
-+
-+static void bfq_schedule_dispatch(struct bfq_data *bfqd);
-+
-+#include "bfq-ioc.c"
-+#include "bfq-sched.c"
-+#include "bfq-cgroup-included.c"
-+
-+#define bfq_class_idle(bfqq)	((bfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
-+#define bfq_class_rt(bfqq)	((bfqq)->ioprio_class == IOPRIO_CLASS_RT)
-+
-+#define bfq_sample_valid(samples)	((samples) > 80)
-+
-+/*
-+ * Scheduler run of queue, if there are requests pending and no one in the
-+ * driver that will restart queueing.
-+ */
-+static void bfq_schedule_dispatch(struct bfq_data *bfqd)
-+{
-+	if (bfqd->queued != 0) {
-+		bfq_log(bfqd, "");
-+		kblockd_schedule_work(&bfqd->unplug_work);
-+	}
-+}
-+
-+/*
-+ * Lifted from AS - choose which of rq1 and rq2 that is best served now.
-+ * We choose the request that is closesr to the head right now.  Distance
-+ * behind the head is penalized and only allowed to a certain extent.
-+ */
-+static struct request *bfq_choose_req(struct bfq_data *bfqd,
-+				      struct request *rq1,
-+				      struct request *rq2,
-+				      sector_t last)
-+{
-+	sector_t s1, s2, d1 = 0, d2 = 0;
-+	unsigned long back_max;
-+#define BFQ_RQ1_WRAP	0x01 /* request 1 wraps */
-+#define BFQ_RQ2_WRAP	0x02 /* request 2 wraps */
-+	unsigned int wrap = 0; /* bit mask: requests behind the disk head? */
-+
-+	if (!rq1 || rq1 == rq2)
-+		return rq2;
-+	if (!rq2)
-+		return rq1;
-+
-+	if (rq_is_sync(rq1) && !rq_is_sync(rq2))
-+		return rq1;
-+	else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
-+		return rq2;
-+	if ((rq1->cmd_flags & REQ_META) && !(rq2->cmd_flags & REQ_META))
-+		return rq1;
-+	else if ((rq2->cmd_flags & REQ_META) && !(rq1->cmd_flags & REQ_META))
-+		return rq2;
-+
-+	s1 = blk_rq_pos(rq1);
-+	s2 = blk_rq_pos(rq2);
-+
-+	/*
-+	 * By definition, 1KiB is 2 sectors.
-+	 */
-+	back_max = bfqd->bfq_back_max * 2;
-+
-+	/*
-+	 * Strict one way elevator _except_ in the case where we allow
-+	 * short backward seeks which are biased as twice the cost of a
-+	 * similar forward seek.
-+	 */
-+	if (s1 >= last)
-+		d1 = s1 - last;
-+	else if (s1 + back_max >= last)
-+		d1 = (last - s1) * bfqd->bfq_back_penalty;
-+	else
-+		wrap |= BFQ_RQ1_WRAP;
-+
-+	if (s2 >= last)
-+		d2 = s2 - last;
-+	else if (s2 + back_max >= last)
-+		d2 = (last - s2) * bfqd->bfq_back_penalty;
-+	else
-+		wrap |= BFQ_RQ2_WRAP;
-+
-+	/* Found required data */
-+
-+	/*
-+	 * By doing switch() on the bit mask "wrap" we avoid having to
-+	 * check two variables for all permutations: --> faster!
-+	 */
-+	switch (wrap) {
-+	case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
-+		if (d1 < d2)
-+			return rq1;
-+		else if (d2 < d1)
-+			return rq2;
-+
-+		if (s1 >= s2)
-+			return rq1;
-+		else
-+			return rq2;
-+
-+	case BFQ_RQ2_WRAP:
-+		return rq1;
-+	case BFQ_RQ1_WRAP:
-+		return rq2;
-+	case (BFQ_RQ1_WRAP|BFQ_RQ2_WRAP): /* both rqs wrapped */
-+	default:
-+		/*
-+		 * Since both rqs are wrapped,
-+		 * start with the one that's further behind head
-+		 * (--> only *one* back seek required),
-+		 * since back seek takes more time than forward.
-+		 */
-+		if (s1 <= s2)
-+			return rq1;
-+		else
-+			return rq2;
-+	}
-+}
-+
-+static struct bfq_queue *
-+bfq_rq_pos_tree_lookup(struct bfq_data *bfqd, struct rb_root *root,
-+		     sector_t sector, struct rb_node **ret_parent,
-+		     struct rb_node ***rb_link)
-+{
-+	struct rb_node **p, *parent;
-+	struct bfq_queue *bfqq = NULL;
-+
-+	parent = NULL;
-+	p = &root->rb_node;
-+	while (*p) {
-+		struct rb_node **n;
-+
-+		parent = *p;
-+		bfqq = rb_entry(parent, struct bfq_queue, pos_node);
-+
-+		/*
-+		 * Sort strictly based on sector. Smallest to the left,
-+		 * largest to the right.
-+		 */
-+		if (sector > blk_rq_pos(bfqq->next_rq))
-+			n = &(*p)->rb_right;
-+		else if (sector < blk_rq_pos(bfqq->next_rq))
-+			n = &(*p)->rb_left;
-+		else
-+			break;
-+		p = n;
-+		bfqq = NULL;
-+	}
-+
-+	*ret_parent = parent;
-+	if (rb_link)
-+		*rb_link = p;
-+
-+	bfq_log(bfqd, "%llu: returning %d",
-+		(unsigned long long) sector,
-+		bfqq ? bfqq->pid : 0);
-+
-+	return bfqq;
-+}
-+
-+static bool bfq_too_late_for_merging(struct bfq_queue *bfqq)
-+{
-+	return bfqq->service_from_backlogged > 0 &&
-+		time_is_before_jiffies(bfqq->first_IO_time +
-+				       bfq_merge_time_limit);
-+}
-+
-+static void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	struct rb_node **p, *parent;
-+	struct bfq_queue *__bfqq;
-+
-+	if (bfqq->pos_root) {
-+		rb_erase(&bfqq->pos_node, bfqq->pos_root);
-+		bfqq->pos_root = NULL;
-+	}
-+
-+	/*
-+	 * bfqq cannot be merged any longer (see comments in
-+	 * bfq_setup_cooperator): no point in adding bfqq into the
-+	 * position tree.
-+	 */
-+	if (bfq_too_late_for_merging(bfqq))
-+		return;
-+
-+	if (bfq_class_idle(bfqq))
-+		return;
-+	if (!bfqq->next_rq)
-+		return;
-+
-+	bfqq->pos_root = &bfq_bfqq_to_bfqg(bfqq)->rq_pos_tree;
-+	__bfqq = bfq_rq_pos_tree_lookup(bfqd, bfqq->pos_root,
-+			blk_rq_pos(bfqq->next_rq), &parent, &p);
-+	if (!__bfqq) {
-+		rb_link_node(&bfqq->pos_node, parent, p);
-+		rb_insert_color(&bfqq->pos_node, bfqq->pos_root);
-+	} else
-+		bfqq->pos_root = NULL;
-+}
-+
-+/*
-+ * The following function returns true if every queue must receive the
-+ * same share of the throughput (this condition is used when deciding
-+ * whether idling may be disabled, see the comments in the function
-+ * bfq_better_to_idle()).
-+ *
-+ * Such a scenario occurs when:
-+ * 1) all active queues have the same weight,
-+ * 2) all active queues belong to the same I/O-priority class,
-+ * 3) all active groups at the same level in the groups tree have the same
-+ *    weight,
-+ * 4) all active groups at the same level in the groups tree have the same
-+ *    number of children.
-+ *
-+ * Unfortunately, keeping the necessary state for evaluating exactly
-+ * the last two symmetry sub-conditions above would be quite complex
-+ * and time consuming. Therefore this function evaluates, instead,
-+ * only the following stronger three sub-conditions, for which it is
-+ * much easier to maintain the needed state:
-+ * 1) all active queues have the same weight,
-+ * 2) all active queues belong to the same I/O-priority class,
-+ * 3) there are no active groups.
-+ * In particular, the last condition is always true if hierarchical
-+ * support or the cgroups interface are not enabled, thus no state
-+ * needs to be maintained in this case.
-+ */
-+static bool bfq_symmetric_scenario(struct bfq_data *bfqd)
-+{
-+	/*
-+	 * For queue weights to differ, queue_weights_tree must contain
-+	 * at least two nodes.
-+	 */
-+	bool varied_queue_weights = !RB_EMPTY_ROOT(&bfqd->queue_weights_tree) &&
-+		(bfqd->queue_weights_tree.rb_node->rb_left ||
-+		 bfqd->queue_weights_tree.rb_node->rb_right);
-+
-+	bool multiple_classes_busy =
-+		(bfqd->busy_queues[0] && bfqd->busy_queues[1]) ||
-+		(bfqd->busy_queues[0] && bfqd->busy_queues[2]) ||
-+		(bfqd->busy_queues[1] && bfqd->busy_queues[2]);
-+
-+	bfq_log(bfqd, "varied_queue_weights %d mul_classes %d",
-+		varied_queue_weights, multiple_classes_busy);
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	bfq_log(bfqd, "num_groups_with_pending_reqs %u",
-+		bfqd->num_groups_with_pending_reqs);
-+#endif
-+
-+	return !(varied_queue_weights || multiple_classes_busy
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	       || bfqd->num_groups_with_pending_reqs > 0
-+#endif
-+		);
-+}
-+
-+/*
-+ * If the weight-counter tree passed as input contains no counter for
-+ * the weight of the input queue, then add that counter; otherwise just
-+ * increment the existing counter.
-+ *
-+ * Note that weight-counter trees contain few nodes in mostly symmetric
-+ * scenarios. For example, if all queues have the same weight, then the
-+ * weight-counter tree for the queues may contain at most one node.
-+ * This holds even if low_latency is on, because weight-raised queues
-+ * are not inserted in the tree.
-+ * In most scenarios, the rate at which nodes are created/destroyed
-+ * should be low too.
-+ */
-+static void bfq_weights_tree_add(struct bfq_data *bfqd,
-+				 struct bfq_queue *bfqq,
-+				 struct rb_root *root)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+	struct rb_node **new = &(root->rb_node), *parent = NULL;
-+
-+	/*
-+	 * Do not insert if the queue is already associated with a
-+	 * counter, which happens if:
-+	 *   1) a request arrival has caused the queue to become both
-+	 *      non-weight-raised, and hence change its weight, and
-+	 *      backlogged; in this respect, each of the two events
-+	 *      causes an invocation of this function,
-+	 *   2) this is the invocation of this function caused by the
-+	 *      second event. This second invocation is actually useless,
-+	 *      and we handle this fact by exiting immediately. More
-+	 *      efficient or clearer solutions might possibly be adopted.
-+	 */
-+	if (bfqq->weight_counter)
-+		return;
-+
-+	while (*new) {
-+		struct bfq_weight_counter *__counter = container_of(*new,
-+						struct bfq_weight_counter,
-+						weights_node);
-+		parent = *new;
-+
-+		if (entity->weight == __counter->weight) {
-+			bfqq->weight_counter = __counter;
-+			goto inc_counter;
-+		}
-+		if (entity->weight < __counter->weight)
-+			new = &((*new)->rb_left);
-+		else
-+			new = &((*new)->rb_right);
-+	}
-+
-+	bfqq->weight_counter = kzalloc(sizeof(struct bfq_weight_counter),
-+				       GFP_ATOMIC);
-+
-+	/*
-+	 * In the unlucky event of an allocation failure, we just
-+	 * exit. This will cause the weight of queue to not be
-+	 * considered in bfq_symmetric_scenario, which, in its turn,
-+	 * causes the scenario to be deemed wrongly symmetric in case
-+	 * bfqq's weight would have been the only weight making the
-+	 * scenario asymmetric.  On the bright side, no unbalance will
-+	 * however occur when bfqq becomes inactive again (the
-+	 * invocation of this function is triggered by an activation
-+	 * of queue).  In fact, bfq_weights_tree_remove does nothing
-+	 * if !bfqq->weight_counter.
-+	 */
-+	if (unlikely(!bfqq->weight_counter))
-+		return;
-+
-+	bfqq->weight_counter->weight = entity->weight;
-+	rb_link_node(&bfqq->weight_counter->weights_node, parent, new);
-+	rb_insert_color(&bfqq->weight_counter->weights_node, root);
-+
-+inc_counter:
-+	bfqq->weight_counter->num_active++;
-+	bfqq->ref++;
-+
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "refs %d weight %d symmetric %d",
-+				bfqq->ref,
-+				entity->weight,
-+				bfq_symmetric_scenario(bfqd));
-+}
-+
-+/*
-+ * Decrement the weight counter associated with the queue, and, if the
-+ * counter reaches 0, remove the counter from the tree.
-+ * See the comments to the function bfq_weights_tree_add() for considerations
-+ * about overhead.
-+ */
-+static void __bfq_weights_tree_remove(struct bfq_data *bfqd,
-+				      struct bfq_queue *bfqq,
-+				      struct rb_root *root)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+
-+	if (!bfqq->weight_counter)
-+		return;
-+
-+	BUG_ON(RB_EMPTY_ROOT(root));
-+	BUG_ON(bfqq->weight_counter->weight != entity->weight);
-+
-+	BUG_ON(!bfqq->weight_counter->num_active);
-+	bfqq->weight_counter->num_active--;
-+
-+	if (bfqq->weight_counter->num_active > 0)
-+		goto reset_entity_pointer;
-+
-+	rb_erase(&bfqq->weight_counter->weights_node, root);
-+	kfree(bfqq->weight_counter);
-+
-+reset_entity_pointer:
-+	bfqq->weight_counter = NULL;
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		     "refs %d weight %d symmetric %d",
-+		     bfqq->ref,
-+		     entity->weight,
-+		     bfq_symmetric_scenario(bfqd));
-+	bfq_put_queue(bfqq);
-+}
-+
-+/*
-+ * Invoke __bfq_weights_tree_remove on bfqq and decrement the number
-+ * of active groups for each queue's inactive parent entity.
-+ */
-+static void bfq_weights_tree_remove(struct bfq_data *bfqd,
-+				    struct bfq_queue *bfqq)
-+{
-+	struct bfq_entity *entity = bfqq->entity.parent;
-+
-+	for_each_entity(entity) {
-+		struct bfq_sched_data *sd = entity->my_sched_data;
-+
-+		BUG_ON(entity->sched_data == NULL); /*
-+						     * It would mean
-+						     * that this is
-+						     * the root group.
-+						     */
-+
-+		if (sd->next_in_service || sd->in_service_entity) {
-+			BUG_ON(!entity->in_groups_with_pending_reqs);
-+			/*
-+			 * entity is still active, because either
-+			 * next_in_service or in_service_entity is not
-+			 * NULL (see the comments on the definition of
-+			 * next_in_service for details on why
-+			 * in_service_entity must be checked too).
-+			 *
-+			 * As a consequence, its parent entities are
-+			 * active as well, and thus this loop must
-+			 * stop here.
-+			 */
-+			break;
-+		}
-+
-+		BUG_ON(!bfqd->num_groups_with_pending_reqs &&
-+		       entity->in_groups_with_pending_reqs);
-+		/*
-+		 * The decrement of num_groups_with_pending_reqs is
-+		 * not performed immediately upon the deactivation of
-+		 * entity, but it is delayed to when it also happens
-+		 * that the first leaf descendant bfqq of entity gets
-+		 * all its pending requests completed. The following
-+		 * instructions perform this delayed decrement, if
-+		 * needed. See the comments on
-+		 * num_groups_with_pending_reqs for details.
-+		 */
-+		if (entity->in_groups_with_pending_reqs) {
-+			entity->in_groups_with_pending_reqs = false;
-+			bfqd->num_groups_with_pending_reqs--;
-+		}
-+		bfq_log_bfqq(bfqd, bfqq, "num_groups_with_pending_reqs %u",
-+			     bfqd->num_groups_with_pending_reqs);
-+	}
-+
-+	/*
-+	 * Next function is invoked last, because it causes bfqq to be
-+	 * freed if the following holds: bfqq is not in service and
-+	 * has no dispatched request. DO NOT use bfqq after the next
-+	 * function invocation.
-+	 */
-+	__bfq_weights_tree_remove(bfqd, bfqq,
-+				  &bfqd->queue_weights_tree);
-+}
-+
-+/*
-+ * Return expired entry, or NULL to just start from scratch in rbtree.
-+ */
-+static struct request *bfq_check_fifo(struct bfq_queue *bfqq,
-+				      struct request *last)
-+{
-+	struct request *rq;
-+
-+	if (bfq_bfqq_fifo_expire(bfqq))
-+		return NULL;
-+
-+	bfq_mark_bfqq_fifo_expire(bfqq);
-+
-+	rq = rq_entry_fifo(bfqq->fifo.next);
-+
-+	if (rq == last || ktime_get_ns() < rq->fifo_time)
-+		return NULL;
-+
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "returned %p", rq);
-+	BUG_ON(RB_EMPTY_NODE(&rq->rb_node));
-+	return rq;
-+}
-+
-+static struct request *bfq_find_next_rq(struct bfq_data *bfqd,
-+					struct bfq_queue *bfqq,
-+					struct request *last)
-+{
-+	struct rb_node *rbnext = rb_next(&last->rb_node);
-+	struct rb_node *rbprev = rb_prev(&last->rb_node);
-+	struct request *next, *prev = NULL;
-+
-+	BUG_ON(list_empty(&bfqq->fifo));
-+
-+	/* Follow expired path, else get first next available. */
-+	next = bfq_check_fifo(bfqq, last);
-+	if (next) {
-+		BUG_ON(next == last);
-+		return next;
-+	}
-+
-+	BUG_ON(RB_EMPTY_NODE(&last->rb_node));
-+
-+	if (rbprev)
-+		prev = rb_entry_rq(rbprev);
-+
-+	if (rbnext)
-+		next = rb_entry_rq(rbnext);
-+	else {
-+		rbnext = rb_first(&bfqq->sort_list);
-+		if (rbnext && rbnext != &last->rb_node)
-+			next = rb_entry_rq(rbnext);
-+	}
-+
-+	return bfq_choose_req(bfqd, next, prev, blk_rq_pos(last));
-+}
-+
-+/* see the definition of bfq_async_charge_factor for details */
-+static unsigned long bfq_serv_to_charge(struct request *rq,
-+					struct bfq_queue *bfqq)
-+{
-+	if (bfq_bfqq_sync(bfqq) || bfqq->wr_coeff > 1 ||
-+	    !bfq_symmetric_scenario(bfqq->bfqd))
-+		return blk_rq_sectors(rq);
-+
-+	return blk_rq_sectors(rq) * bfq_async_charge_factor;
-+}
-+
-+/**
-+ * bfq_updated_next_req - update the queue after a new next_rq selection.
-+ * @bfqd: the device data the queue belongs to.
-+ * @bfqq: the queue to update.
-+ *
-+ * If the first request of a queue changes we make sure that the queue
-+ * has enough budget to serve at least its first request (if the
-+ * request has grown).  We do this because if the queue has not enough
-+ * budget for its first request, it has to go through two dispatch
-+ * rounds to actually get it dispatched.
-+ */
-+static void bfq_updated_next_req(struct bfq_data *bfqd,
-+				 struct bfq_queue *bfqq)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+	struct bfq_service_tree *st = bfq_entity_service_tree(entity);
-+	struct request *next_rq = bfqq->next_rq;
-+	unsigned long new_budget;
-+
-+	if (!next_rq)
-+		return;
-+
-+	if (bfqq == bfqd->in_service_queue)
-+		/*
-+		 * In order not to break guarantees, budgets cannot be
-+		 * changed after an entity has been selected.
-+		 */
-+		return;
-+
-+	BUG_ON(entity->tree != &st->active);
-+	BUG_ON(entity == entity->sched_data->in_service_entity);
-+
-+	new_budget = max_t(unsigned long,
-+			   max_t(unsigned long, bfqq->max_budget,
-+				 bfq_serv_to_charge(next_rq, bfqq)),
-+			   entity->service);
-+	if (entity->budget != new_budget) {
-+		entity->budget = new_budget;
-+		bfq_log_bfqq(bfqd, bfqq, "new budget %lu",
-+					 new_budget);
-+		bfq_requeue_bfqq(bfqd, bfqq, false);
-+	}
-+}
-+
-+static unsigned int bfq_wr_duration(struct bfq_data *bfqd)
-+{
-+	u64 dur;
-+
-+	if (bfqd->bfq_wr_max_time > 0)
-+		return bfqd->bfq_wr_max_time;
-+
-+	dur = bfqd->rate_dur_prod;
-+	do_div(dur, bfqd->peak_rate);
-+
-+	/*
-+	 * Limit duration between 3 and 25 seconds. The upper limit
-+	 * has been conservatively set after the following worst case:
-+	 * on a QEMU/KVM virtual machine
-+	 * - running in a slow PC
-+	 * - with a virtual disk stacked on a slow low-end 5400rpm HDD
-+	 * - serving a heavy I/O workload, such as the sequential reading
-+	 *   of several files
-+	 * mplayer took 23 seconds to start, if constantly weight-raised.
-+	 *
-+	 * As for higher values than that accomodating the above bad
-+	 * scenario, tests show that higher values would often yield
-+	 * the opposite of the desired result, i.e., would worsen
-+	 * responsiveness by allowing non-interactive applications to
-+	 * preserve weight raising for too long.
-+	 *
-+	 * On the other end, lower values than 3 seconds make it
-+	 * difficult for most interactive tasks to complete their jobs
-+	 * before weight-raising finishes.
-+	 */
-+	return clamp_val(dur, msecs_to_jiffies(3000), msecs_to_jiffies(25000));
-+}
-+
-+/* switch back from soft real-time to interactive weight raising */
-+static void switch_back_to_interactive_wr(struct bfq_queue *bfqq,
-+					  struct bfq_data *bfqd)
-+{
-+	bfqq->wr_coeff = bfqd->bfq_wr_coeff;
-+	bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
-+	bfqq->last_wr_start_finish = bfqq->wr_start_at_switch_to_srt;
-+}
-+
-+static void
-+bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_data *bfqd,
-+		      struct bfq_io_cq *bic, bool bfq_already_existing)
-+{
-+	unsigned int old_wr_coeff;
-+	bool busy = bfq_already_existing && bfq_bfqq_busy(bfqq);
-+
-+	if (bic->saved_has_short_ttime)
-+		bfq_mark_bfqq_has_short_ttime(bfqq);
-+	else
-+		bfq_clear_bfqq_has_short_ttime(bfqq);
-+
-+	if (bic->saved_IO_bound)
-+		bfq_mark_bfqq_IO_bound(bfqq);
-+	else
-+		bfq_clear_bfqq_IO_bound(bfqq);
-+
-+	if (unlikely(busy))
-+		old_wr_coeff = bfqq->wr_coeff;
-+
-+	bfqq->wr_coeff = bic->saved_wr_coeff;
-+	bfqq->wr_start_at_switch_to_srt = bic->saved_wr_start_at_switch_to_srt;
-+	BUG_ON(time_is_after_jiffies(bfqq->wr_start_at_switch_to_srt));
-+	bfqq->last_wr_start_finish = bic->saved_last_wr_start_finish;
-+	bfqq->wr_cur_max_time = bic->saved_wr_cur_max_time;
-+	BUG_ON(time_is_after_jiffies(bfqq->last_wr_start_finish));
-+
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		     "bic %p wr_coeff %d start_finish %lu max_time %lu",
-+		     bic, bfqq->wr_coeff, bfqq->last_wr_start_finish,
-+		     bfqq->wr_cur_max_time);
-+
-+	if (bfqq->wr_coeff > 1 && (bfq_bfqq_in_large_burst(bfqq) ||
-+				   time_is_before_jiffies(bfqq->last_wr_start_finish +
-+							  bfqq->wr_cur_max_time))) {
-+		if (bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time &&
-+		    !bfq_bfqq_in_large_burst(bfqq) &&
-+		    time_is_after_eq_jiffies(bfqq->wr_start_at_switch_to_srt +
-+					     bfq_wr_duration(bfqd))) {
-+			switch_back_to_interactive_wr(bfqq, bfqd);
-+			bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			     "switching back to interactive");
-+		} else {
-+			bfqq->wr_coeff = 1;
-+			bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			     "switching off wr (%lu + %lu < %lu)",
-+			     bfqq->last_wr_start_finish, bfqq->wr_cur_max_time,
-+			     jiffies);
-+		}
-+	}
-+
-+	/* make sure weight will be updated, however we got here */
-+	bfqq->entity.prio_changed = 1;
-+
-+	if (likely(!busy))
-+		return;
-+
-+	if (old_wr_coeff == 1 && bfqq->wr_coeff > 1) {
-+		bfqd->wr_busy_queues++;
-+		BUG_ON(bfqd->wr_busy_queues > bfq_tot_busy_queues(bfqd));
-+	} else if (old_wr_coeff > 1 && bfqq->wr_coeff == 1) {
-+		bfqd->wr_busy_queues--;
-+		BUG_ON(bfqd->wr_busy_queues < 0);
-+	}
-+}
-+
-+static int bfqq_process_refs(struct bfq_queue *bfqq)
-+{
-+	int process_refs, io_refs;
-+
-+	lockdep_assert_held(bfqq->bfqd->queue->queue_lock);
-+
-+	io_refs = bfqq->allocated[READ] + bfqq->allocated[WRITE];
-+	process_refs = bfqq->ref - io_refs - bfqq->entity.on_st -
-+		(bfqq->weight_counter != NULL);
-+	BUG_ON(process_refs < 0);
-+	return process_refs;
-+}
-+
-+/* Empty burst list and add just bfqq (see comments to bfq_handle_burst) */
-+static void bfq_reset_burst_list(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	struct bfq_queue *item;
-+	struct hlist_node *n;
-+
-+	hlist_for_each_entry_safe(item, n, &bfqd->burst_list, burst_list_node)
-+		hlist_del_init(&item->burst_list_node);
-+	hlist_add_head(&bfqq->burst_list_node, &bfqd->burst_list);
-+	bfqd->burst_size = 1;
-+	bfqd->burst_parent_entity = bfqq->entity.parent;
-+}
-+
-+/* Add bfqq to the list of queues in current burst (see bfq_handle_burst) */
-+static void bfq_add_to_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	/* Increment burst size to take into account also bfqq */
-+	bfqd->burst_size++;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "%d", bfqd->burst_size);
-+
-+	BUG_ON(bfqd->burst_size > bfqd->bfq_large_burst_thresh);
-+
-+	if (bfqd->burst_size == bfqd->bfq_large_burst_thresh) {
-+		struct bfq_queue *pos, *bfqq_item;
-+		struct hlist_node *n;
-+
-+		/*
-+		 * Enough queues have been activated shortly after each
-+		 * other to consider this burst as large.
-+		 */
-+		bfqd->large_burst = true;
-+		bfq_log_bfqq(bfqd, bfqq, "large burst started");
-+
-+		/*
-+		 * We can now mark all queues in the burst list as
-+		 * belonging to a large burst.
-+		 */
-+		hlist_for_each_entry(bfqq_item, &bfqd->burst_list,
-+				     burst_list_node) {
-+			bfq_mark_bfqq_in_large_burst(bfqq_item);
-+			bfq_log_bfqq(bfqd, bfqq_item, "marked in large burst");
-+		}
-+		bfq_mark_bfqq_in_large_burst(bfqq);
-+		bfq_log_bfqq(bfqd, bfqq, "marked in large burst");
-+
-+		/*
-+		 * From now on, and until the current burst finishes, any
-+		 * new queue being activated shortly after the last queue
-+		 * was inserted in the burst can be immediately marked as
-+		 * belonging to a large burst. So the burst list is not
-+		 * needed any more. Remove it.
-+		 */
-+		hlist_for_each_entry_safe(pos, n, &bfqd->burst_list,
-+					  burst_list_node)
-+			hlist_del_init(&pos->burst_list_node);
-+	} else /*
-+		* Burst not yet large: add bfqq to the burst list. Do
-+		* not increment the ref counter for bfqq, because bfqq
-+		* is removed from the burst list before freeing bfqq
-+		* in put_queue.
-+		*/
-+		hlist_add_head(&bfqq->burst_list_node, &bfqd->burst_list);
-+}
-+
-+/*
-+ * If many queues belonging to the same group happen to be created
-+ * shortly after each other, then the processes associated with these
-+ * queues have typically a common goal. In particular, bursts of queue
-+ * creations are usually caused by services or applications that spawn
-+ * many parallel threads/processes. Examples are systemd during boot,
-+ * or git grep. To help these processes get their job done as soon as
-+ * possible, it is usually better to not grant either weight-raising
-+ * or device idling to their queues.
-+ *
-+ * In this comment we describe, firstly, the reasons why this fact
-+ * holds, and, secondly, the next function, which implements the main
-+ * steps needed to properly mark these queues so that they can then be
-+ * treated in a different way.
-+ *
-+ * The above services or applications benefit mostly from a high
-+ * throughput: the quicker the requests of the activated queues are
-+ * cumulatively served, the sooner the target job of these queues gets
-+ * completed. As a consequence, weight-raising any of these queues,
-+ * which also implies idling the device for it, is almost always
-+ * counterproductive. In most cases it just lowers throughput.
-+ *
-+ * On the other hand, a burst of queue creations may be caused also by
-+ * the start of an application that does not consist of a lot of
-+ * parallel I/O-bound threads. In fact, with a complex application,
-+ * several short processes may need to be executed to start-up the
-+ * application. In this respect, to start an application as quickly as
-+ * possible, the best thing to do is in any case to privilege the I/O
-+ * related to the application with respect to all other
-+ * I/O. Therefore, the best strategy to start as quickly as possible
-+ * an application that causes a burst of queue creations is to
-+ * weight-raise all the queues created during the burst. This is the
-+ * exact opposite of the best strategy for the other type of bursts.
-+ *
-+ * In the end, to take the best action for each of the two cases, the
-+ * two types of bursts need to be distinguished. Fortunately, this
-+ * seems relatively easy, by looking at the sizes of the bursts. In
-+ * particular, we found a threshold such that only bursts with a
-+ * larger size than that threshold are apparently caused by
-+ * services or commands such as systemd or git grep. For brevity,
-+ * hereafter we call just 'large' these bursts. BFQ *does not*
-+ * weight-raise queues whose creation occurs in a large burst. In
-+ * addition, for each of these queues BFQ performs or does not perform
-+ * idling depending on which choice boosts the throughput more. The
-+ * exact choice depends on the device and request pattern at
-+ * hand.
-+ *
-+ * Unfortunately, false positives may occur while an interactive task
-+ * is starting (e.g., an application is being started). The
-+ * consequence is that the queues associated with the task do not
-+ * enjoy weight raising as expected. Fortunately these false positives
-+ * are very rare. They typically occur if some service happens to
-+ * start doing I/O exactly when the interactive task starts.
-+ *
-+ * Turning back to the next function, it implements all the steps
-+ * needed to detect the occurrence of a large burst and to properly
-+ * mark all the queues belonging to it (so that they can then be
-+ * treated in a different way). This goal is achieved by maintaining a
-+ * "burst list" that holds, temporarily, the queues that belong to the
-+ * burst in progress. The list is then used to mark these queues as
-+ * belonging to a large burst if the burst does become large. The main
-+ * steps are the following.
-+ *
-+ * . when the very first queue is created, the queue is inserted into the
-+ *   list (as it could be the first queue in a possible burst)
-+ *
-+ * . if the current burst has not yet become large, and a queue Q that does
-+ *   not yet belong to the burst is activated shortly after the last time
-+ *   at which a new queue entered the burst list, then the function appends
-+ *   Q to the burst list
-+ *
-+ * . if, as a consequence of the previous step, the burst size reaches
-+ *   the large-burst threshold, then
-+ *
-+ *     . all the queues in the burst list are marked as belonging to a
-+ *       large burst
-+ *
-+ *     . the burst list is deleted; in fact, the burst list already served
-+ *       its purpose (keeping temporarily track of the queues in a burst,
-+ *       so as to be able to mark them as belonging to a large burst in the
-+ *       previous sub-step), and now is not needed any more
-+ *
-+ *     . the device enters a large-burst mode
-+ *
-+ * . if a queue Q that does not belong to the burst is created while
-+ *   the device is in large-burst mode and shortly after the last time
-+ *   at which a queue either entered the burst list or was marked as
-+ *   belonging to the current large burst, then Q is immediately marked
-+ *   as belonging to a large burst.
-+ *
-+ * . if a queue Q that does not belong to the burst is created a while
-+ *   later, i.e., not shortly after, than the last time at which a queue
-+ *   either entered the burst list or was marked as belonging to the
-+ *   current large burst, then the current burst is deemed as finished and:
-+ *
-+ *        . the large-burst mode is reset if set
-+ *
-+ *        . the burst list is emptied
-+ *
-+ *        . Q is inserted in the burst list, as Q may be the first queue
-+ *          in a possible new burst (then the burst list contains just Q
-+ *          after this step).
-+ */
-+static void bfq_handle_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	/*
-+	 * If bfqq is already in the burst list or is part of a large
-+	 * burst, or finally has just been split, then there is
-+	 * nothing else to do.
-+	 */
-+	if (!hlist_unhashed(&bfqq->burst_list_node) ||
-+	    bfq_bfqq_in_large_burst(bfqq) ||
-+	    time_is_after_eq_jiffies(bfqq->split_time +
-+				     msecs_to_jiffies(10)))
-+		return;
-+
-+	/*
-+	 * If bfqq's creation happens late enough, or bfqq belongs to
-+	 * a different group than the burst group, then the current
-+	 * burst is finished, and related data structures must be
-+	 * reset.
-+	 *
-+	 * In this respect, consider the special case where bfqq is
-+	 * the very first queue created after BFQ is selected for this
-+	 * device. In this case, last_ins_in_burst and
-+	 * burst_parent_entity are not yet significant when we get
-+	 * here. But it is easy to verify that, whether or not the
-+	 * following condition is true, bfqq will end up being
-+	 * inserted into the burst list. In particular the list will
-+	 * happen to contain only bfqq. And this is exactly what has
-+	 * to happen, as bfqq may be the first queue of the first
-+	 * burst.
-+	 */
-+	if (time_is_before_jiffies(bfqd->last_ins_in_burst +
-+	    bfqd->bfq_burst_interval) ||
-+	    bfqq->entity.parent != bfqd->burst_parent_entity) {
-+		bfqd->large_burst = false;
-+		bfq_reset_burst_list(bfqd, bfqq);
-+		bfq_log_bfqq(bfqd, bfqq,
-+			"late activation or different group");
-+		goto end;
-+	}
-+
-+	/*
-+	 * If we get here, then bfqq is being activated shortly after the
-+	 * last queue. So, if the current burst is also large, we can mark
-+	 * bfqq as belonging to this large burst immediately.
-+	 */
-+	if (bfqd->large_burst) {
-+		bfq_log_bfqq(bfqd, bfqq, "marked in burst");
-+		bfq_mark_bfqq_in_large_burst(bfqq);
-+		goto end;
-+	}
-+
-+	/*
-+	 * If we get here, then a large-burst state has not yet been
-+	 * reached, but bfqq is being activated shortly after the last
-+	 * queue. Then we add bfqq to the burst.
-+	 */
-+	bfq_add_to_burst(bfqd, bfqq);
-+end:
-+	/*
-+	 * At this point, bfqq either has been added to the current
-+	 * burst or has caused the current burst to terminate and a
-+	 * possible new burst to start. In particular, in the second
-+	 * case, bfqq has become the first queue in the possible new
-+	 * burst.  In both cases last_ins_in_burst needs to be moved
-+	 * forward.
-+	 */
-+	bfqd->last_ins_in_burst = jiffies;
-+
-+}
-+
-+static int bfq_bfqq_budget_left(struct bfq_queue *bfqq)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+
-+	if (entity->budget < entity->service) {
-+		pr_crit("budget %d service %d\n",
-+			entity->budget, entity->service);
-+		BUG();
-+	}
-+	return entity->budget - entity->service;
-+}
-+
-+/*
-+ * If enough samples have been computed, return the current max budget
-+ * stored in bfqd, which is dynamically updated according to the
-+ * estimated disk peak rate; otherwise return the default max budget
-+ */
-+static int bfq_max_budget(struct bfq_data *bfqd)
-+{
-+	if (bfqd->budgets_assigned < bfq_stats_min_budgets)
-+		return bfq_default_max_budget;
-+	else
-+		return bfqd->bfq_max_budget;
-+}
-+
-+/*
-+ * Return min budget, which is a fraction of the current or default
-+ * max budget (trying with 1/32)
-+ */
-+static int bfq_min_budget(struct bfq_data *bfqd)
-+{
-+	if (bfqd->budgets_assigned < bfq_stats_min_budgets)
-+		return bfq_default_max_budget / 32;
-+	else
-+		return bfqd->bfq_max_budget / 32;
-+}
-+
-+static void bfq_bfqq_expire(struct bfq_data *bfqd,
-+			    struct bfq_queue *bfqq,
-+			    bool compensate,
-+			    enum bfqq_expiration reason);
-+
-+/*
-+ * The next function, invoked after the input queue bfqq switches from
-+ * idle to busy, updates the budget of bfqq. The function also tells
-+ * whether the in-service queue should be expired, by returning
-+ * true. The purpose of expiring the in-service queue is to give bfqq
-+ * the chance to possibly preempt the in-service queue, and the reason
-+ * for preempting the in-service queue is to achieve one of the two
-+ * goals below.
-+ *
-+ * 1. Guarantee to bfqq its reserved bandwidth even if bfqq has
-+ * expired because it has remained idle. In particular, bfqq may have
-+ * expired for one of the following two reasons:
-+ *
-+ * - BFQ_BFQQ_NO_MORE_REQUEST bfqq did not enjoy any device idling and
-+ *   did not make it to issue a new request before its last request
-+ *   was served;
-+ *
-+ * - BFQ_BFQQ_TOO_IDLE bfqq did enjoy device idling, but did not issue
-+ *   a new request before the expiration of the idling-time.
-+ *
-+ * Even if bfqq has expired for one of the above reasons, the process
-+ * associated with the queue may be however issuing requests greedily,
-+ * and thus be sensitive to the bandwidth it receives (bfqq may have
-+ * remained idle for other reasons: CPU high load, bfqq not enjoying
-+ * idling, I/O throttling somewhere in the path from the process to
-+ * the I/O scheduler, ...). But if, after every expiration for one of
-+ * the above two reasons, bfqq has to wait for the service of at least
-+ * one full budget of another queue before being served again, then
-+ * bfqq is likely to get a much lower bandwidth or resource time than
-+ * its reserved ones. To address this issue, two countermeasures need
-+ * to be taken.
-+ *
-+ * First, the budget and the timestamps of bfqq need to be updated in
-+ * a special way on bfqq reactivation: they need to be updated as if
-+ * bfqq did not remain idle and did not expire. In fact, if they are
-+ * computed as if bfqq expired and remained idle until reactivation,
-+ * then the process associated with bfqq is treated as if, instead of
-+ * being greedy, it stopped issuing requests when bfqq remained idle,
-+ * and restarts issuing requests only on this reactivation. In other
-+ * words, the scheduler does not help the process recover the "service
-+ * hole" between bfqq expiration and reactivation. As a consequence,
-+ * the process receives a lower bandwidth than its reserved one. In
-+ * contrast, to recover this hole, the budget must be updated as if
-+ * bfqq was not expired at all before this reactivation, i.e., it must
-+ * be set to the value of the remaining budget when bfqq was
-+ * expired. Along the same line, timestamps need to be assigned the
-+ * value they had the last time bfqq was selected for service, i.e.,
-+ * before last expiration. Thus timestamps need to be back-shifted
-+ * with respect to their normal computation (see [1] for more details
-+ * on this tricky aspect).
-+ *
-+ * Secondly, to allow the process to recover the hole, the in-service
-+ * queue must be expired too, to give bfqq the chance to preempt it
-+ * immediately. In fact, if bfqq has to wait for a full budget of the
-+ * in-service queue to be completed, then it may become impossible to
-+ * let the process recover the hole, even if the back-shifted
-+ * timestamps of bfqq are lower than those of the in-service queue. If
-+ * this happens for most or all of the holes, then the process may not
-+ * receive its reserved bandwidth. In this respect, it is worth noting
-+ * that, being the service of outstanding requests unpreemptible, a
-+ * little fraction of the holes may however be unrecoverable, thereby
-+ * causing a little loss of bandwidth.
-+ *
-+ * The last important point is detecting whether bfqq does need this
-+ * bandwidth recovery. In this respect, the next function deems the
-+ * process associated with bfqq greedy, and thus allows it to recover
-+ * the hole, if: 1) the process is waiting for the arrival of a new
-+ * request (which implies that bfqq expired for one of the above two
-+ * reasons), and 2) such a request has arrived soon. The first
-+ * condition is controlled through the flag non_blocking_wait_rq,
-+ * while the second through the flag arrived_in_time. If both
-+ * conditions hold, then the function computes the budget in the
-+ * above-described special way, and signals that the in-service queue
-+ * should be expired. Timestamp back-shifting is done later in
-+ * __bfq_activate_entity.
-+ *
-+ * 2. Reduce latency. Even if timestamps are not backshifted to let
-+ * the process associated with bfqq recover a service hole, bfqq may
-+ * however happen to have, after being (re)activated, a lower finish
-+ * timestamp than the in-service queue.  That is, the next budget of
-+ * bfqq may have to be completed before the one of the in-service
-+ * queue. If this is the case, then preempting the in-service queue
-+ * allows this goal to be achieved, apart from the unpreemptible,
-+ * outstanding requests mentioned above.
-+ *
-+ * Unfortunately, regardless of which of the above two goals one wants
-+ * to achieve, service trees need first to be updated to know whether
-+ * the in-service queue must be preempted. To have service trees
-+ * correctly updated, the in-service queue must be expired and
-+ * rescheduled, and bfqq must be scheduled too. This is one of the
-+ * most costly operations (in future versions, the scheduling
-+ * mechanism may be re-designed in such a way to make it possible to
-+ * know whether preemption is needed without needing to update service
-+ * trees). In addition, queue preemptions almost always cause random
-+ * I/O, and thus loss of throughput. Because of these facts, the next
-+ * function adopts the following simple scheme to avoid both costly
-+ * operations and too frequent preemptions: it requests the expiration
-+ * of the in-service queue (unconditionally) only for queues that need
-+ * to recover a hole, or that either are weight-raised or deserve to
-+ * be weight-raised.
-+ */
-+static bool bfq_bfqq_update_budg_for_activation(struct bfq_data *bfqd,
-+						struct bfq_queue *bfqq,
-+						bool arrived_in_time,
-+						bool wr_or_deserves_wr)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+
-+	/*
-+	 * In the next compound condition, we check also whether there
-+	 * is some budget left, because otherwise there is no point in
-+	 * trying to go on serving bfqq with this same budget: bfqq
-+	 * would be expired immediately after being selected for
-+	 * service. This would only cause useless overhead.
-+	 */
-+	if (bfq_bfqq_non_blocking_wait_rq(bfqq) && arrived_in_time &&
-+	    bfq_bfqq_budget_left(bfqq) > 0) {
-+		/*
-+		 * We do not clear the flag non_blocking_wait_rq here, as
-+		 * the latter is used in bfq_activate_bfqq to signal
-+		 * that timestamps need to be back-shifted (and is
-+		 * cleared right after).
-+		 */
-+
-+		/*
-+		 * In next assignment we rely on that either
-+		 * entity->service or entity->budget are not updated
-+		 * on expiration if bfqq is empty (see
-+		 * __bfq_bfqq_recalc_budget). Thus both quantities
-+		 * remain unchanged after such an expiration, and the
-+		 * following statement therefore assigns to
-+		 * entity->budget the remaining budget on such an
-+		 * expiration.
-+		 */
-+		BUG_ON(bfqq->max_budget < 0);
-+		entity->budget = min_t(unsigned long,
-+				       bfq_bfqq_budget_left(bfqq),
-+				       bfqq->max_budget);
-+
-+		BUG_ON(entity->budget < 0);
-+
-+		/*
-+		 * At this point, we have used entity->service to get
-+		 * the budget left (needed for updating
-+		 * entity->budget). Thus we finally can, and have to,
-+		 * reset entity->service. The latter must be reset
-+		 * because bfqq would otherwise be charged again for
-+		 * the service it has received during its previous
-+		 * service slot(s).
-+		 */
-+		entity->service = 0;
-+
-+		return true;
-+	}
-+
-+	/*
-+	 * We can finally complete expiration, by setting service to 0.
-+	 */
-+	entity->service = 0;
-+	BUG_ON(bfqq->max_budget < 0);
-+	entity->budget = max_t(unsigned long, bfqq->max_budget,
-+			       bfq_serv_to_charge(bfqq->next_rq, bfqq));
-+	BUG_ON(entity->budget < 0);
-+
-+	bfq_clear_bfqq_non_blocking_wait_rq(bfqq);
-+	return wr_or_deserves_wr;
-+}
-+
-+/*
-+ * Return the farthest past time instant according to jiffies
-+ * macros.
-+ */
-+static unsigned long bfq_smallest_from_now(void)
-+{
-+	return jiffies - MAX_JIFFY_OFFSET;
-+}
-+
-+static void bfq_update_bfqq_wr_on_rq_arrival(struct bfq_data *bfqd,
-+					     struct bfq_queue *bfqq,
-+					     unsigned int old_wr_coeff,
-+					     bool wr_or_deserves_wr,
-+					     bool interactive,
-+					     bool in_burst,
-+					     bool soft_rt)
-+{
-+	if (old_wr_coeff == 1 && wr_or_deserves_wr) {
-+		/* start a weight-raising period */
-+		if (interactive) {
-+			bfqq->service_from_wr = 0;
-+			bfqq->wr_coeff = bfqd->bfq_wr_coeff;
-+			bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
-+		} else {
-+			/*
-+			 * No interactive weight raising in progress
-+			 * here: assign minus infinity to
-+			 * wr_start_at_switch_to_srt, to make sure
-+			 * that, at the end of the soft-real-time
-+			 * weight raising periods that is starting
-+			 * now, no interactive weight-raising period
-+			 * may be wrongly considered as still in
-+			 * progress (and thus actually started by
-+			 * mistake).
-+			 */
-+			bfqq->wr_start_at_switch_to_srt =
-+				bfq_smallest_from_now();
-+			bfqq->wr_coeff = bfqd->bfq_wr_coeff *
-+				BFQ_SOFTRT_WEIGHT_FACTOR;
-+			bfqq->wr_cur_max_time =
-+				bfqd->bfq_wr_rt_max_time;
-+		}
-+		/*
-+		 * If needed, further reduce budget to make sure it is
-+		 * close to bfqq's backlog, so as to reduce the
-+		 * scheduling-error component due to a too large
-+		 * budget. Do not care about throughput consequences,
-+		 * but only about latency. Finally, do not assign a
-+		 * too small budget either, to avoid increasing
-+		 * latency by causing too frequent expirations.
-+		 */
-+		bfqq->entity.budget = min_t(unsigned long,
-+					    bfqq->entity.budget,
-+					    2 * bfq_min_budget(bfqd));
-+
-+		bfq_log_bfqq(bfqd, bfqq,
-+			     "wrais starting at %lu, rais_max_time %u",
-+			     jiffies,
-+			     jiffies_to_msecs(bfqq->wr_cur_max_time));
-+	} else if (old_wr_coeff > 1) {
-+		if (interactive) { /* update wr coeff and duration */
-+			bfqq->wr_coeff = bfqd->bfq_wr_coeff;
-+			bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
-+		} else if (in_burst) {
-+			bfqq->wr_coeff = 1;
-+			bfq_log_bfqq(bfqd, bfqq,
-+				     "wrais ending at %lu, rais_max_time %u",
-+				     jiffies,
-+				     jiffies_to_msecs(bfqq->
-+						      wr_cur_max_time));
-+		} else if (soft_rt) {
-+			/*
-+			 * The application is now or still meeting the
-+			 * requirements for being deemed soft rt.  We
-+			 * can then correctly and safely (re)charge
-+			 * the weight-raising duration for the
-+			 * application with the weight-raising
-+			 * duration for soft rt applications.
-+			 *
-+			 * In particular, doing this recharge now, i.e.,
-+			 * before the weight-raising period for the
-+			 * application finishes, reduces the probability
-+			 * of the following negative scenario:
-+			 * 1) the weight of a soft rt application is
-+			 *    raised at startup (as for any newly
-+			 *    created application),
-+			 * 2) since the application is not interactive,
-+			 *    at a certain time weight-raising is
-+			 *    stopped for the application,
-+			 * 3) at that time the application happens to
-+			 *    still have pending requests, and hence
-+			 *    is destined to not have a chance to be
-+			 *    deemed soft rt before these requests are
-+			 *    completed (see the comments to the
-+			 *    function bfq_bfqq_softrt_next_start()
-+			 *    for details on soft rt detection),
-+			 * 4) these pending requests experience a high
-+			 *    latency because the application is not
-+			 *    weight-raised while they are pending.
-+			 */
-+			if (bfqq->wr_cur_max_time !=
-+				bfqd->bfq_wr_rt_max_time) {
-+				bfqq->wr_start_at_switch_to_srt =
-+					bfqq->last_wr_start_finish;
-+                BUG_ON(time_is_after_jiffies(bfqq->last_wr_start_finish));
-+
-+				bfqq->wr_cur_max_time =
-+					bfqd->bfq_wr_rt_max_time;
-+				bfqq->wr_coeff = bfqd->bfq_wr_coeff *
-+					BFQ_SOFTRT_WEIGHT_FACTOR;
-+				bfq_log_bfqq(bfqd, bfqq,
-+					     "switching to soft_rt wr");
-+			} else
-+				bfq_log_bfqq(bfqd, bfqq,
-+					"moving forward soft_rt wr duration");
-+			bfqq->last_wr_start_finish = jiffies;
-+		}
-+	}
-+}
-+
-+static bool bfq_bfqq_idle_for_long_time(struct bfq_data *bfqd,
-+					struct bfq_queue *bfqq)
-+{
-+	return bfqq->dispatched == 0 &&
-+		time_is_before_jiffies(
-+			bfqq->budget_timeout +
-+			bfqd->bfq_wr_min_idle_time);
-+}
-+
-+static void bfq_bfqq_handle_idle_busy_switch(struct bfq_data *bfqd,
-+					     struct bfq_queue *bfqq,
-+					     int old_wr_coeff,
-+					     struct request *rq,
-+					     bool *interactive)
-+{
-+	bool soft_rt, in_burst,	wr_or_deserves_wr,
-+		bfqq_wants_to_preempt,
-+		idle_for_long_time = bfq_bfqq_idle_for_long_time(bfqd, bfqq),
-+		/*
-+		 * See the comments on
-+		 * bfq_bfqq_update_budg_for_activation for
-+		 * details on the usage of the next variable.
-+		 */
-+		arrived_in_time =  ktime_get_ns() <=
-+			RQ_BIC(rq)->ttime.last_end_request +
-+			bfqd->bfq_slice_idle * 3;
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+		     "bfq_add_request non-busy: "
-+		     "jiffies %lu, in_time %d, idle_long %d busyw %d "
-+		     "wr_coeff %u",
-+		     jiffies, arrived_in_time,
-+		     idle_for_long_time,
-+		     bfq_bfqq_non_blocking_wait_rq(bfqq),
-+		     old_wr_coeff);
-+
-+	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
-+
-+	BUG_ON(bfqq == bfqd->in_service_queue);
-+	bfqg_stats_update_io_add(bfqq_group(RQ_BFQQ(rq)), bfqq, rq->cmd_flags);
-+
-+	/*
-+	 * bfqq deserves to be weight-raised if:
-+	 * - it is sync,
-+	 * - it does not belong to a large burst,
-+	 * - it has been idle for enough time or is soft real-time,
-+	 * - is linked to a bfq_io_cq (it is not shared in any sense)
-+	 */
-+	in_burst = bfq_bfqq_in_large_burst(bfqq);
-+	soft_rt = bfqd->bfq_wr_max_softrt_rate > 0 &&
-+		!in_burst &&
-+		time_is_before_jiffies(bfqq->soft_rt_next_start) &&
-+		bfqq->dispatched == 0;
-+	*interactive =
-+		!in_burst &&
-+		idle_for_long_time;
-+	wr_or_deserves_wr = bfqd->low_latency &&
-+		(bfqq->wr_coeff > 1 ||
-+		 (bfq_bfqq_sync(bfqq) &&
-+		  bfqq->bic && (*interactive || soft_rt)));
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+		     "bfq_add_request: "
-+		     "in_burst %d, "
-+		     "soft_rt %d (next %lu), inter %d, bic %p",
-+		     bfq_bfqq_in_large_burst(bfqq), soft_rt,
-+		     bfqq->soft_rt_next_start,
-+		     *interactive,
-+		     bfqq->bic);
-+
-+	/*
-+	 * Using the last flag, update budget and check whether bfqq
-+	 * may want to preempt the in-service queue.
-+	 */
-+	bfqq_wants_to_preempt =
-+		bfq_bfqq_update_budg_for_activation(bfqd, bfqq,
-+						    arrived_in_time,
-+						    wr_or_deserves_wr);
-+
-+	/*
-+	 * If bfqq happened to be activated in a burst, but has been
-+	 * idle for much more than an interactive queue, then we
-+	 * assume that, in the overall I/O initiated in the burst, the
-+	 * I/O associated with bfqq is finished. So bfqq does not need
-+	 * to be treated as a queue belonging to a burst
-+	 * anymore. Accordingly, we reset bfqq's in_large_burst flag
-+	 * if set, and remove bfqq from the burst list if it's
-+	 * there. We do not decrement burst_size, because the fact
-+	 * that bfqq does not need to belong to the burst list any
-+	 * more does not invalidate the fact that bfqq was created in
-+	 * a burst.
-+	 */
-+	if (likely(!bfq_bfqq_just_created(bfqq)) &&
-+	    idle_for_long_time &&
-+	    time_is_before_jiffies(
-+		    bfqq->budget_timeout +
-+		    msecs_to_jiffies(10000))) {
-+		hlist_del_init(&bfqq->burst_list_node);
-+		bfq_clear_bfqq_in_large_burst(bfqq);
-+	}
-+
-+	bfq_clear_bfqq_just_created(bfqq);
-+
-+	if (!bfq_bfqq_IO_bound(bfqq)) {
-+		if (arrived_in_time) {
-+			bfqq->requests_within_timer++;
-+			if (bfqq->requests_within_timer >=
-+			    bfqd->bfq_requests_within_timer)
-+				bfq_mark_bfqq_IO_bound(bfqq);
-+		} else
-+			bfqq->requests_within_timer = 0;
-+		bfq_log_bfqq(bfqd, bfqq, "requests in time %d",
-+			     bfqq->requests_within_timer);
-+	}
-+
-+	if (bfqd->low_latency) {
-+		if (unlikely(time_is_after_jiffies(bfqq->split_time)))
-+			/* wraparound */
-+			bfqq->split_time =
-+				jiffies - bfqd->bfq_wr_min_idle_time - 1;
-+
-+		if (time_is_before_jiffies(bfqq->split_time +
-+					   bfqd->bfq_wr_min_idle_time)) {
-+			bfq_update_bfqq_wr_on_rq_arrival(bfqd, bfqq,
-+							 old_wr_coeff,
-+							 wr_or_deserves_wr,
-+							 *interactive,
-+							 in_burst,
-+							 soft_rt);
-+
-+			if (old_wr_coeff != bfqq->wr_coeff)
-+				bfqq->entity.prio_changed = 1;
-+		}
-+	}
-+
-+	bfqq->last_idle_bklogged = jiffies;
-+	bfqq->service_from_backlogged = 0;
-+	bfq_clear_bfqq_softrt_update(bfqq);
-+
-+	bfq_add_bfqq_busy(bfqd, bfqq);
-+
-+	/*
-+	 * Expire in-service queue only if preemption may be needed
-+	 * for guarantees. In this respect, the function
-+	 * next_queue_may_preempt just checks a simple, necessary
-+	 * condition, and not a sufficient condition based on
-+	 * timestamps. In fact, for the latter condition to be
-+	 * evaluated, timestamps would need first to be updated, and
-+	 * this operation is quite costly (see the comments on the
-+	 * function bfq_bfqq_update_budg_for_activation).
-+	 */
-+	if (bfqd->in_service_queue && bfqq_wants_to_preempt &&
-+	    bfqd->in_service_queue->wr_coeff < bfqq->wr_coeff &&
-+	    next_queue_may_preempt(bfqd)) {
-+		struct bfq_queue *in_serv =
-+			bfqd->in_service_queue;
-+		BUG_ON(in_serv == bfqq);
-+
-+		bfq_bfqq_expire(bfqd, bfqd->in_service_queue,
-+				false, BFQ_BFQQ_PREEMPTED);
-+	}
-+}
-+
-+static void bfq_add_request(struct request *rq)
-+{
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq);
-+	struct bfq_data *bfqd = bfqq->bfqd;
-+	struct request *next_rq, *prev;
-+	unsigned int old_wr_coeff = bfqq->wr_coeff;
-+	bool interactive = false;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "size %u %s",
-+		     blk_rq_sectors(rq), rq_is_sync(rq) ? "S" : "A");
-+
-+	if (bfqq->wr_coeff > 1) /* queue is being weight-raised */
-+		bfq_log_bfqq(bfqd, bfqq,
-+			"raising period dur %u/%u msec, old coeff %u, w %d(%d)",
-+			jiffies_to_msecs(jiffies - bfqq->last_wr_start_finish),
-+			jiffies_to_msecs(bfqq->wr_cur_max_time),
-+			bfqq->wr_coeff,
-+			bfqq->entity.weight, bfqq->entity.orig_weight);
-+
-+	bfqq->queued[rq_is_sync(rq)]++;
-+	bfqd->queued++;
-+
-+	elv_rb_add(&bfqq->sort_list, rq);
-+
-+	/*
-+	 * Check if this request is a better next-to-serve candidate.
-+	 */
-+	prev = bfqq->next_rq;
-+	next_rq = bfq_choose_req(bfqd, bfqq->next_rq, rq, bfqd->last_position);
-+	BUG_ON(!next_rq);
-+	bfqq->next_rq = next_rq;
-+
-+	/*
-+	 * Adjust priority tree position, if next_rq changes.
-+	 */
-+	if (prev != bfqq->next_rq)
-+		bfq_pos_tree_add_move(bfqd, bfqq);
-+
-+	if (!bfq_bfqq_busy(bfqq)) /* switching to busy ... */
-+		bfq_bfqq_handle_idle_busy_switch(bfqd, bfqq, old_wr_coeff,
-+						 rq, &interactive);
-+	else {
-+		if (bfqd->low_latency && old_wr_coeff == 1 && !rq_is_sync(rq) &&
-+		    time_is_before_jiffies(
-+				bfqq->last_wr_start_finish +
-+				bfqd->bfq_wr_min_inter_arr_async)) {
-+			bfqq->wr_coeff = bfqd->bfq_wr_coeff;
-+			bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
-+
-+			bfqd->wr_busy_queues++;
-+			BUG_ON(bfqd->wr_busy_queues > bfq_tot_busy_queues(bfqd));
-+			bfqq->entity.prio_changed = 1;
-+			bfq_log_bfqq(bfqd, bfqq,
-+				     "non-idle wrais starting, "
-+				     "wr_max_time %u wr_busy %d",
-+				     jiffies_to_msecs(bfqq->wr_cur_max_time),
-+				     bfqd->wr_busy_queues);
-+		}
-+		if (prev != bfqq->next_rq)
-+			bfq_updated_next_req(bfqd, bfqq);
-+	}
-+
-+	/*
-+	 * Assign jiffies to last_wr_start_finish in the following
-+	 * cases:
-+	 *
-+	 * . if bfqq is not going to be weight-raised, because, for
-+	 *   non weight-raised queues, last_wr_start_finish stores the
-+	 *   arrival time of the last request; as of now, this piece
-+	 *   of information is used only for deciding whether to
-+	 *   weight-raise async queues
-+	 *
-+	 * . if bfqq is not weight-raised, because, if bfqq is now
-+	 *   switching to weight-raised, then last_wr_start_finish
-+	 *   stores the time when weight-raising starts
-+	 *
-+	 * . if bfqq is interactive, because, regardless of whether
-+	 *   bfqq is currently weight-raised, the weight-raising
-+	 *   period must start or restart (this case is considered
-+	 *   separately because it is not detected by the above
-+	 *   conditions, if bfqq is already weight-raised)
-+	 *
-+	 * last_wr_start_finish has to be updated also if bfqq is soft
-+	 * real-time, because the weight-raising period is constantly
-+	 * restarted on idle-to-busy transitions for these queues, but
-+	 * this is already done in bfq_bfqq_handle_idle_busy_switch if
-+	 * needed.
-+	 */
-+	if (bfqd->low_latency &&
-+		(old_wr_coeff == 1 || bfqq->wr_coeff == 1 || interactive))
-+		bfqq->last_wr_start_finish = jiffies;
-+}
-+
-+static struct request *bfq_find_rq_fmerge(struct bfq_data *bfqd,
-+					  struct bio *bio)
-+{
-+	struct task_struct *tsk = current;
-+	struct bfq_io_cq *bic;
-+	struct bfq_queue *bfqq;
-+
-+	bic = bfq_bic_lookup(bfqd, tsk->io_context);
-+	if (!bic)
-+		return NULL;
-+
-+	bfqq = bic_to_bfqq(bic, op_is_sync(bio->bi_opf));
-+	if (bfqq)
-+		return elv_rb_find(&bfqq->sort_list, bio_end_sector(bio));
-+
-+	return NULL;
-+}
-+
-+static sector_t get_sdist(sector_t last_pos, struct request *rq)
-+{
-+	sector_t sdist = 0;
-+
-+	if (last_pos) {
-+		if (last_pos < blk_rq_pos(rq))
-+			sdist = blk_rq_pos(rq) - last_pos;
-+		else
-+			sdist = last_pos - blk_rq_pos(rq);
-+	}
-+
-+	return sdist;
-+}
-+
-+static void bfq_activate_request(struct request_queue *q, struct request *rq)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	bfqd->rq_in_driver++;
-+}
-+
-+static void bfq_deactivate_request(struct request_queue *q, struct request *rq)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+
-+	BUG_ON(bfqd->rq_in_driver == 0);
-+	bfqd->rq_in_driver--;
-+}
-+
-+static void bfq_remove_request(struct request *rq)
-+{
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq);
-+	struct bfq_data *bfqd = bfqq->bfqd;
-+	const int sync = rq_is_sync(rq);
-+
-+	/*
-+	 * NOTE:
-+	 * (bfqq->entity.service > bfqq->entity.budget) may hold here,
-+	 * in case of forced dispatches.
-+	 */
-+
-+	if (bfqq->next_rq == rq) {
-+		bfqq->next_rq = bfq_find_next_rq(bfqd, bfqq, rq);
-+		bfq_updated_next_req(bfqd, bfqq);
-+	}
-+
-+	if (rq->queuelist.prev != &rq->queuelist)
-+		list_del_init(&rq->queuelist);
-+	BUG_ON(bfqq->queued[sync] == 0);
-+	bfqq->queued[sync]--;
-+	bfqd->queued--;
-+	elv_rb_del(&bfqq->sort_list, rq);
-+
-+	if (RB_EMPTY_ROOT(&bfqq->sort_list)) {
-+		bfqq->next_rq = NULL;
-+
-+		BUG_ON(bfqq->entity.budget < 0);
-+
-+		if (bfq_bfqq_busy(bfqq) && bfqq != bfqd->in_service_queue) {
-+			BUG_ON(bfqq->ref < 2); /* referred by rq and on tree */
-+			bfq_del_bfqq_busy(bfqd, bfqq, false);
-+			/*
-+			 * bfqq emptied. In normal operation, when
-+			 * bfqq is empty, bfqq->entity.service and
-+			 * bfqq->entity.budget must contain,
-+			 * respectively, the service received and the
-+			 * budget used last time bfqq emptied. These
-+			 * facts do not hold in this case, as at least
-+			 * this last removal occurred while bfqq is
-+			 * not in service. To avoid inconsistencies,
-+			 * reset both bfqq->entity.service and
-+			 * bfqq->entity.budget, if bfqq has still a
-+			 * process that may issue I/O requests to it.
-+			 */
-+			bfqq->entity.budget = bfqq->entity.service = 0;
-+		}
-+
-+		/*
-+		 * Remove queue from request-position tree as it is empty.
-+		 */
-+		if (bfqq->pos_root) {
-+			rb_erase(&bfqq->pos_node, bfqq->pos_root);
-+			bfqq->pos_root = NULL;
-+		}
-+	} else {
-+		BUG_ON(!bfqq->next_rq);
-+		bfq_pos_tree_add_move(bfqd, bfqq);
-+	}
-+
-+	if (rq->cmd_flags & REQ_META) {
-+		BUG_ON(bfqq->meta_pending == 0);
-+		bfqq->meta_pending--;
-+	}
-+	bfqg_stats_update_io_remove(bfqq_group(bfqq), rq->cmd_flags);
-+}
-+
-+static enum elv_merge bfq_merge(struct request_queue *q, struct request **req,
-+				struct bio *bio)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	struct request *__rq;
-+
-+	__rq = bfq_find_rq_fmerge(bfqd, bio);
-+	if (__rq && elv_bio_merge_ok(__rq, bio)) {
-+		*req = __rq;
-+		return ELEVATOR_FRONT_MERGE;
-+	}
-+
-+	return ELEVATOR_NO_MERGE;
-+}
-+
-+static void bfq_merged_request(struct request_queue *q, struct request *req,
-+			       enum elv_merge type)
-+{
-+	if (type == ELEVATOR_FRONT_MERGE &&
-+	    rb_prev(&req->rb_node) &&
-+	    blk_rq_pos(req) <
-+	    blk_rq_pos(container_of(rb_prev(&req->rb_node),
-+				    struct request, rb_node))) {
-+		struct bfq_queue *bfqq = RQ_BFQQ(req);
-+		struct bfq_data *bfqd = bfqq->bfqd;
-+		struct request *prev, *next_rq;
-+
-+		/* Reposition request in its sort_list */
-+		elv_rb_del(&bfqq->sort_list, req);
-+		elv_rb_add(&bfqq->sort_list, req);
-+		/* Choose next request to be served for bfqq */
-+		prev = bfqq->next_rq;
-+		next_rq = bfq_choose_req(bfqd, bfqq->next_rq, req,
-+					 bfqd->last_position);
-+		BUG_ON(!next_rq);
-+		bfqq->next_rq = next_rq;
-+		/*
-+		 * If next_rq changes, update both the queue's budget to
-+		 * fit the new request and the queue's position in its
-+		 * rq_pos_tree.
-+		 */
-+		if (prev != bfqq->next_rq) {
-+			bfq_updated_next_req(bfqd, bfqq);
-+			bfq_pos_tree_add_move(bfqd, bfqq);
-+		}
-+	}
-+}
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+static void bfq_bio_merged(struct request_queue *q, struct request *req,
-+			   struct bio *bio)
-+{
-+	bfqg_stats_update_io_merged(bfqq_group(RQ_BFQQ(req)), bio->bi_opf);
-+}
-+#endif
-+
-+static void bfq_merged_requests(struct request_queue *q, struct request *rq,
-+				struct request *next)
-+{
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq), *next_bfqq = RQ_BFQQ(next);
-+
-+	/*
-+	 * If next and rq belong to the same bfq_queue and next is older
-+	 * than rq, then reposition rq in the fifo (by substituting next
-+	 * with rq). Otherwise, if next and rq belong to different
-+	 * bfq_queues, never reposition rq: in fact, we would have to
-+	 * reposition it with respect to next's position in its own fifo,
-+	 * which would most certainly be too expensive with respect to
-+	 * the benefits.
-+	 */
-+	if (bfqq == next_bfqq &&
-+	    !list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
-+	    next->fifo_time < rq->fifo_time) {
-+		list_del_init(&rq->queuelist);
-+		list_replace_init(&next->queuelist, &rq->queuelist);
-+		rq->fifo_time = next->fifo_time;
-+	}
-+
-+	if (bfqq->next_rq == next)
-+		bfqq->next_rq = rq;
-+
-+	bfq_remove_request(next);
-+	bfqg_stats_update_io_merged(bfqq_group(bfqq), next->cmd_flags);
-+}
-+
-+/* Must be called with bfqq != NULL */
-+static void bfq_bfqq_end_wr(struct bfq_queue *bfqq)
-+{
-+	BUG_ON(!bfqq);
-+
-+	if (bfq_bfqq_busy(bfqq)) {
-+		bfqq->bfqd->wr_busy_queues--;
-+		BUG_ON(bfqq->bfqd->wr_busy_queues < 0);
-+	}
-+	bfqq->wr_coeff = 1;
-+	bfqq->wr_cur_max_time = 0;
-+	bfqq->last_wr_start_finish = jiffies;
-+	/*
-+	 * Trigger a weight change on the next invocation of
-+	 * __bfq_entity_update_weight_prio.
-+	 */
-+	bfqq->entity.prio_changed = 1;
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		     "wrais ending at %lu, rais_max_time %u",
-+		     bfqq->last_wr_start_finish,
-+		     jiffies_to_msecs(bfqq->wr_cur_max_time));
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "wr_busy %d",
-+		     bfqq->bfqd->wr_busy_queues);
-+}
-+
-+static void bfq_end_wr_async_queues(struct bfq_data *bfqd,
-+				    struct bfq_group *bfqg)
-+{
-+	int i, j;
-+
-+	for (i = 0; i < 2; i++)
-+		for (j = 0; j < IOPRIO_BE_NR; j++)
-+			if (bfqg->async_bfqq[i][j])
-+				bfq_bfqq_end_wr(bfqg->async_bfqq[i][j]);
-+	if (bfqg->async_idle_bfqq)
-+		bfq_bfqq_end_wr(bfqg->async_idle_bfqq);
-+}
-+
-+static void bfq_end_wr(struct bfq_data *bfqd)
-+{
-+	struct bfq_queue *bfqq;
-+
-+	spin_lock_irq(bfqd->queue->queue_lock);
-+
-+	list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list)
-+		bfq_bfqq_end_wr(bfqq);
-+	list_for_each_entry(bfqq, &bfqd->idle_list, bfqq_list)
-+		bfq_bfqq_end_wr(bfqq);
-+	bfq_end_wr_async(bfqd);
-+
-+	spin_unlock_irq(bfqd->queue->queue_lock);
-+}
-+
-+static sector_t bfq_io_struct_pos(void *io_struct, bool request)
-+{
-+	if (request)
-+		return blk_rq_pos(io_struct);
-+	else
-+		return ((struct bio *)io_struct)->bi_iter.bi_sector;
-+}
-+
-+static int bfq_rq_close_to_sector(void *io_struct, bool request,
-+				  sector_t sector)
-+{
-+	return abs(bfq_io_struct_pos(io_struct, request) - sector) <=
-+	       BFQQ_CLOSE_THR;
-+}
-+
-+static struct bfq_queue *bfqq_find_close(struct bfq_data *bfqd,
-+					 struct bfq_queue *bfqq,
-+					 sector_t sector)
-+{
-+	struct rb_root *root = &bfq_bfqq_to_bfqg(bfqq)->rq_pos_tree;
-+	struct rb_node *parent, *node;
-+	struct bfq_queue *__bfqq;
-+
-+	if (RB_EMPTY_ROOT(root))
-+		return NULL;
-+
-+	/*
-+	 * First, if we find a request starting at the end of the last
-+	 * request, choose it.
-+	 */
-+	__bfqq = bfq_rq_pos_tree_lookup(bfqd, root, sector, &parent, NULL);
-+	if (__bfqq)
-+		return __bfqq;
-+
-+	/*
-+	 * If the exact sector wasn't found, the parent of the NULL leaf
-+	 * will contain the closest sector (rq_pos_tree sorted by
-+	 * next_request position).
-+	 */
-+	__bfqq = rb_entry(parent, struct bfq_queue, pos_node);
-+	if (bfq_rq_close_to_sector(__bfqq->next_rq, true, sector))
-+		return __bfqq;
-+
-+	if (blk_rq_pos(__bfqq->next_rq) < sector)
-+		node = rb_next(&__bfqq->pos_node);
-+	else
-+		node = rb_prev(&__bfqq->pos_node);
-+	if (!node)
-+		return NULL;
-+
-+	__bfqq = rb_entry(node, struct bfq_queue, pos_node);
-+	if (bfq_rq_close_to_sector(__bfqq->next_rq, true, sector))
-+		return __bfqq;
-+
-+	return NULL;
-+}
-+
-+static struct bfq_queue *bfq_find_close_cooperator(struct bfq_data *bfqd,
-+						   struct bfq_queue *cur_bfqq,
-+						   sector_t sector)
-+{
-+	struct bfq_queue *bfqq;
-+
-+	/*
-+	 * We shall notice if some of the queues are cooperating,
-+	 * e.g., working closely on the same area of the device. In
-+	 * that case, we can group them together and: 1) don't waste
-+	 * time idling, and 2) serve the union of their requests in
-+	 * the best possible order for throughput.
-+	 */
-+	bfqq = bfqq_find_close(bfqd, cur_bfqq, sector);
-+	if (!bfqq || bfqq == cur_bfqq)
-+		return NULL;
-+
-+	return bfqq;
-+}
-+
-+static struct bfq_queue *
-+bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq)
-+{
-+	int process_refs, new_process_refs;
-+	struct bfq_queue *__bfqq;
-+
-+	/*
-+	 * If there are no process references on the new_bfqq, then it is
-+	 * unsafe to follow the ->new_bfqq chain as other bfqq's in the chain
-+	 * may have dropped their last reference (not just their last process
-+	 * reference).
-+	 */
-+	if (!bfqq_process_refs(new_bfqq))
-+		return NULL;
-+
-+	/* Avoid a circular list and skip interim queue merges. */
-+	while ((__bfqq = new_bfqq->new_bfqq)) {
-+		if (__bfqq == bfqq)
-+			return NULL;
-+		new_bfqq = __bfqq;
-+	}
-+
-+	process_refs = bfqq_process_refs(bfqq);
-+	new_process_refs = bfqq_process_refs(new_bfqq);
-+	/*
-+	 * If the process for the bfqq has gone away, there is no
-+	 * sense in merging the queues.
-+	 */
-+	if (process_refs == 0 || new_process_refs == 0)
-+		return NULL;
-+
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "scheduling merge with queue %d",
-+		new_bfqq->pid);
-+
-+	/*
-+	 * Merging is just a redirection: the requests of the process
-+	 * owning one of the two queues are redirected to the other queue.
-+	 * The latter queue, in its turn, is set as shared if this is the
-+	 * first time that the requests of some process are redirected to
-+	 * it.
-+	 *
-+	 * We redirect bfqq to new_bfqq and not the opposite, because we
-+	 * are in the context of the process owning bfqq, hence we have
-+	 * the io_cq of this process. So we can immediately configure this
-+	 * io_cq to redirect the requests of the process to new_bfqq.
-+	 *
-+	 * NOTE, even if new_bfqq coincides with the in-service queue, the
-+	 * io_cq of new_bfqq is not available, because, if the in-service
-+	 * queue is shared, bfqd->in_service_bic may not point to the
-+	 * io_cq of the in-service queue.
-+	 * Redirecting the requests of the process owning bfqq to the
-+	 * currently in-service queue is in any case the best option, as
-+	 * we feed the in-service queue with new requests close to the
-+	 * last request served and, by doing so, hopefully increase the
-+	 * throughput.
-+	 */
-+	bfqq->new_bfqq = new_bfqq;
-+	new_bfqq->ref += process_refs;
-+	return new_bfqq;
-+}
-+
-+static bool bfq_may_be_close_cooperator(struct bfq_queue *bfqq,
-+					struct bfq_queue *new_bfqq)
-+{
-+	if (bfq_too_late_for_merging(new_bfqq)) {
-+		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			     "too late for bfq%d to be merged",
-+				new_bfqq->pid);
-+		return false;
-+	}
-+
-+	if (bfq_class_idle(bfqq) || bfq_class_idle(new_bfqq) ||
-+	    (bfqq->ioprio_class != new_bfqq->ioprio_class))
-+		return false;
-+
-+	/*
-+	 * If either of the queues has already been detected as seeky,
-+	 * then merging it with the other queue is unlikely to lead to
-+	 * sequential I/O.
-+	 */
-+	if (BFQQ_SEEKY(bfqq) || BFQQ_SEEKY(new_bfqq))
-+		return false;
-+
-+	/*
-+	 * Interleaved I/O is known to be done by (some) applications
-+	 * only for reads, so it does not make sense to merge async
-+	 * queues.
-+	 */
-+	if (!bfq_bfqq_sync(bfqq) || !bfq_bfqq_sync(new_bfqq))
-+		return false;
-+
-+	return true;
-+}
-+
-+/*
-+ * Attempt to schedule a merge of bfqq with the currently in-service
-+ * queue or with a close queue among the scheduled queues.  Return
-+ * NULL if no merge was scheduled, a pointer to the shared bfq_queue
-+ * structure otherwise.
-+ *
-+ * The OOM queue is not allowed to participate to cooperation: in fact, since
-+ * the requests temporarily redirected to the OOM queue could be redirected
-+ * again to dedicated queues at any time, the state needed to correctly
-+ * handle merging with the OOM queue would be quite complex and expensive
-+ * to maintain. Besides, in such a critical condition as an out of memory,
-+ * the benefits of queue merging may be little relevant, or even negligible.
-+ *
-+ * WARNING: queue merging may impair fairness among non-weight raised
-+ * queues, for at least two reasons: 1) the original weight of a
-+ * merged queue may change during the merged state, 2) even being the
-+ * weight the same, a merged queue may be bloated with many more
-+ * requests than the ones produced by its originally-associated
-+ * process.
-+ */
-+static struct bfq_queue *
-+bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+		     void *io_struct, bool request)
-+{
-+	struct bfq_queue *in_service_bfqq, *new_bfqq;
-+
-+	/*
-+	 * Prevent bfqq from being merged if it has been created too
-+	 * long ago. The idea is that true cooperating processes, and
-+	 * thus their associated bfq_queues, are supposed to be
-+	 * created shortly after each other. This is the case, e.g.,
-+	 * for KVM/QEMU and dump I/O threads. Basing on this
-+	 * assumption, the following filtering greatly reduces the
-+	 * probability that two non-cooperating processes, which just
-+	 * happen to do close I/O for some short time interval, have
-+	 * their queues merged by mistake.
-+	 */
-+	if (bfq_too_late_for_merging(bfqq)) {
-+		bfq_log_bfqq(bfqd, bfqq,
-+			     "would have looked for coop, but too late");
-+		return NULL;
-+	}
-+
-+	if (bfqq->new_bfqq)
-+		return bfqq->new_bfqq;
-+
-+	if (!io_struct || unlikely(bfqq == &bfqd->oom_bfqq))
-+		return NULL;
-+
-+	/* If there is only one backlogged queue, don't search. */
-+	if (bfq_tot_busy_queues(bfqd) == 1)
-+		return NULL;
-+
-+	in_service_bfqq = bfqd->in_service_queue;
-+
-+	if (in_service_bfqq && in_service_bfqq != bfqq &&
-+	    likely(in_service_bfqq != &bfqd->oom_bfqq) &&
-+	    bfq_rq_close_to_sector(io_struct, request, bfqd->in_serv_last_pos) &&
-+	    bfqq->entity.parent == in_service_bfqq->entity.parent &&
-+	    bfq_may_be_close_cooperator(bfqq, in_service_bfqq)) {
-+		new_bfqq = bfq_setup_merge(bfqq, in_service_bfqq);
-+		if (new_bfqq)
-+			return new_bfqq;
-+	}
-+	/*
-+	 * Check whether there is a cooperator among currently scheduled
-+	 * queues. The only thing we need is that the bio/request is not
-+	 * NULL, as we need it to establish whether a cooperator exists.
-+	 */
-+	new_bfqq = bfq_find_close_cooperator(bfqd, bfqq,
-+			bfq_io_struct_pos(io_struct, request));
-+
-+	BUG_ON(new_bfqq && bfqq->entity.parent != new_bfqq->entity.parent);
-+
-+	if (new_bfqq && likely(new_bfqq != &bfqd->oom_bfqq) &&
-+	    bfq_may_be_close_cooperator(bfqq, new_bfqq))
-+		return bfq_setup_merge(bfqq, new_bfqq);
-+
-+	return NULL;
-+}
-+
-+static void bfq_bfqq_save_state(struct bfq_queue *bfqq)
-+{
-+	struct bfq_io_cq *bic = bfqq->bic;
-+
-+	/*
-+	 * If !bfqq->bic, the queue is already shared or its requests
-+	 * have already been redirected to a shared queue; both idle window
-+	 * and weight raising state have already been saved. Do nothing.
-+	 */
-+	if (!bic)
-+		return;
-+
-+	bic->saved_has_short_ttime = bfq_bfqq_has_short_ttime(bfqq);
-+	bic->saved_IO_bound = bfq_bfqq_IO_bound(bfqq);
-+	bic->saved_in_large_burst = bfq_bfqq_in_large_burst(bfqq);
-+	bic->was_in_burst_list = !hlist_unhashed(&bfqq->burst_list_node);
-+	if (unlikely(bfq_bfqq_just_created(bfqq) &&
-+		     !bfq_bfqq_in_large_burst(bfqq) &&
-+		     bfqq->bfqd->low_latency)) {
-+		/*
-+		 * bfqq being merged ritgh after being created: bfqq
-+		 * would have deserved interactive weight raising, but
-+		 * did not make it to be set in a weight-raised state,
-+		 * because of this early merge.	Store directly the
-+		 * weight-raising state that would have been assigned
-+		 * to bfqq, so that to avoid that bfqq unjustly fails
-+		 * to enjoy weight raising if split soon.
-+		 */
-+		bic->saved_wr_coeff = bfqq->bfqd->bfq_wr_coeff;
-+		bic->saved_wr_cur_max_time = bfq_wr_duration(bfqq->bfqd);
-+		bic->saved_last_wr_start_finish = jiffies;
-+	} else {
-+		bic->saved_wr_coeff = bfqq->wr_coeff;
-+		bic->saved_wr_start_at_switch_to_srt =
-+			bfqq->wr_start_at_switch_to_srt;
-+		bic->saved_last_wr_start_finish = bfqq->last_wr_start_finish;
-+		bic->saved_wr_cur_max_time = bfqq->wr_cur_max_time;
-+	}
-+	BUG_ON(time_is_after_jiffies(bfqq->last_wr_start_finish));
-+}
-+
-+static void bfq_get_bic_reference(struct bfq_queue *bfqq)
-+{
-+	/*
-+	 * If bfqq->bic has a non-NULL value, the bic to which it belongs
-+	 * is about to begin using a shared bfq_queue.
-+	 */
-+	if (bfqq->bic)
-+		atomic_long_inc(&bfqq->bic->icq.ioc->refcount);
-+}
-+
-+static void
-+bfq_merge_bfqqs(struct bfq_data *bfqd, struct bfq_io_cq *bic,
-+		struct bfq_queue *bfqq, struct bfq_queue *new_bfqq)
-+{
-+	bfq_log_bfqq(bfqd, bfqq, "merging with queue %lu",
-+		     (unsigned long) new_bfqq->pid);
-+	/* Save weight raising and idle window of the merged queues */
-+	bfq_bfqq_save_state(bfqq);
-+	bfq_bfqq_save_state(new_bfqq);
-+	if (bfq_bfqq_IO_bound(bfqq))
-+		bfq_mark_bfqq_IO_bound(new_bfqq);
-+	bfq_clear_bfqq_IO_bound(bfqq);
-+
-+	/*
-+	 * If bfqq is weight-raised, then let new_bfqq inherit
-+	 * weight-raising. To reduce false positives, neglect the case
-+	 * where bfqq has just been created, but has not yet made it
-+	 * to be weight-raised (which may happen because EQM may merge
-+	 * bfqq even before bfq_add_request is executed for the first
-+	 * time for bfqq). Handling this case would however be very
-+	 * easy, thanks to the flag just_created.
-+	 */
-+	if (new_bfqq->wr_coeff == 1 && bfqq->wr_coeff > 1) {
-+		new_bfqq->wr_coeff = bfqq->wr_coeff;
-+		new_bfqq->wr_cur_max_time = bfqq->wr_cur_max_time;
-+		new_bfqq->last_wr_start_finish = bfqq->last_wr_start_finish;
-+		new_bfqq->wr_start_at_switch_to_srt =
-+			bfqq->wr_start_at_switch_to_srt;
-+		if (bfq_bfqq_busy(new_bfqq)) {
-+			bfqd->wr_busy_queues++;
-+			BUG_ON(bfqd->wr_busy_queues >
-+			       bfq_tot_busy_queues(bfqd));
-+		}
-+
-+		new_bfqq->entity.prio_changed = 1;
-+		bfq_log_bfqq(bfqd, new_bfqq,
-+			     "wr start after merge with %d, rais_max_time %u",
-+			     bfqq->pid,
-+			     jiffies_to_msecs(bfqq->wr_cur_max_time));
-+	}
-+
-+	if (bfqq->wr_coeff > 1) { /* bfqq has given its wr to new_bfqq */
-+		bfqq->wr_coeff = 1;
-+		bfqq->entity.prio_changed = 1;
-+		if (bfq_bfqq_busy(bfqq)) {
-+			bfqd->wr_busy_queues--;
-+			BUG_ON(bfqd->wr_busy_queues < 0);
-+		}
-+
-+	}
-+
-+	bfq_log_bfqq(bfqd, new_bfqq, "wr_busy %d",
-+		     bfqd->wr_busy_queues);
-+
-+	/*
-+	 * Grab a reference to the bic, to prevent it from being destroyed
-+	 * before being possibly touched by a bfq_split_bfqq().
-+	 */
-+	bfq_get_bic_reference(bfqq);
-+	bfq_get_bic_reference(new_bfqq);
-+	/*
-+	 * Merge queues (that is, let bic redirect its requests to new_bfqq)
-+	 */
-+	bic_set_bfqq(bic, new_bfqq, 1);
-+	bfq_mark_bfqq_coop(new_bfqq);
-+	/*
-+	 * new_bfqq now belongs to at least two bics (it is a shared queue):
-+	 * set new_bfqq->bic to NULL. bfqq either:
-+	 * - does not belong to any bic any more, and hence bfqq->bic must
-+	 *   be set to NULL, or
-+	 * - is a queue whose owning bics have already been redirected to a
-+	 *   different queue, hence the queue is destined to not belong to
-+	 *   any bic soon and bfqq->bic is already NULL (therefore the next
-+	 *   assignment causes no harm).
-+	 */
-+	new_bfqq->bic = NULL;
-+	bfqq->bic = NULL;
-+	/* release process reference to bfqq */
-+	bfq_put_queue(bfqq);
-+}
-+
-+static int bfq_allow_bio_merge(struct request_queue *q, struct request *rq,
-+			       struct bio *bio)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	bool is_sync = op_is_sync(bio->bi_opf);
-+	struct bfq_io_cq *bic;
-+	struct bfq_queue *bfqq, *new_bfqq;
-+
-+	/*
-+	 * Disallow merge of a sync bio into an async request.
-+	 */
-+	if (is_sync && !rq_is_sync(rq))
-+		return false;
-+
-+	/*
-+	 * Lookup the bfqq that this bio will be queued with. Allow
-+	 * merge only if rq is queued there.
-+	 * Queue lock is held here.
-+	 */
-+	bic = bfq_bic_lookup(bfqd, current->io_context);
-+	if (!bic)
-+		return false;
-+
-+	bfqq = bic_to_bfqq(bic, is_sync);
-+	/*
-+	 * We take advantage of this function to perform an early merge
-+	 * of the queues of possible cooperating processes.
-+	 */
-+	if (bfqq) {
-+		new_bfqq = bfq_setup_cooperator(bfqd, bfqq, bio, false);
-+		if (new_bfqq) {
-+			bfq_merge_bfqqs(bfqd, bic, bfqq, new_bfqq);
-+			/*
-+			 * If we get here, the bio will be queued in the
-+			 * shared queue, i.e., new_bfqq, so use new_bfqq
-+			 * to decide whether bio and rq can be merged.
-+			 */
-+			bfqq = new_bfqq;
-+		}
-+	}
-+
-+	return bfqq == RQ_BFQQ(rq);
-+}
-+
-+static int bfq_allow_rq_merge(struct request_queue *q, struct request *rq,
-+			      struct request *next)
-+{
-+	return RQ_BFQQ(rq) == RQ_BFQQ(next);
-+}
-+
-+/*
-+ * Set the maximum time for the in-service queue to consume its
-+ * budget. This prevents seeky processes from lowering the throughput.
-+ * In practice, a time-slice service scheme is used with seeky
-+ * processes.
-+ */
-+static void bfq_set_budget_timeout(struct bfq_data *bfqd,
-+				   struct bfq_queue *bfqq)
-+{
-+	unsigned int timeout_coeff;
-+
-+	if (bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time)
-+		timeout_coeff = 1;
-+	else
-+		timeout_coeff = bfqq->entity.weight / bfqq->entity.orig_weight;
-+
-+	bfqd->last_budget_start = ktime_get();
-+
-+	bfqq->budget_timeout = jiffies +
-+		bfqd->bfq_timeout * timeout_coeff;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "%u",
-+		jiffies_to_msecs(bfqd->bfq_timeout * timeout_coeff));
-+}
-+
-+static void __bfq_set_in_service_queue(struct bfq_data *bfqd,
-+				       struct bfq_queue *bfqq)
-+{
-+	if (bfqq) {
-+		bfqg_stats_update_avg_queue_size(bfqq_group(bfqq));
-+		bfq_mark_bfqq_must_alloc(bfqq);
-+		bfq_clear_bfqq_fifo_expire(bfqq);
-+
-+		bfqd->budgets_assigned = (bfqd->budgets_assigned*7 + 256) / 8;
-+
-+		BUG_ON(bfqq == bfqd->in_service_queue);
-+		BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list));
-+
-+		if (time_is_before_jiffies(bfqq->last_wr_start_finish) &&
-+		    bfqq->wr_coeff > 1 &&
-+		    bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time &&
-+		    time_is_before_jiffies(bfqq->budget_timeout)) {
-+			/*
-+			 * For soft real-time queues, move the start
-+			 * of the weight-raising period forward by the
-+			 * time the queue has not received any
-+			 * service. Otherwise, a relatively long
-+			 * service delay is likely to cause the
-+			 * weight-raising period of the queue to end,
-+			 * because of the short duration of the
-+			 * weight-raising period of a soft real-time
-+			 * queue.  It is worth noting that this move
-+			 * is not so dangerous for the other queues,
-+			 * because soft real-time queues are not
-+			 * greedy.
-+			 *
-+			 * To not add a further variable, we use the
-+			 * overloaded field budget_timeout to
-+			 * determine for how long the queue has not
-+			 * received service, i.e., how much time has
-+			 * elapsed since the queue expired. However,
-+			 * this is a little imprecise, because
-+			 * budget_timeout is set to jiffies if bfqq
-+			 * not only expires, but also remains with no
-+			 * request.
-+			 */
-+			if (time_after(bfqq->budget_timeout,
-+				       bfqq->last_wr_start_finish))
-+				bfqq->last_wr_start_finish +=
-+					jiffies - bfqq->budget_timeout;
-+			else
-+				bfqq->last_wr_start_finish = jiffies;
-+
-+			if (time_is_after_jiffies(bfqq->last_wr_start_finish)) {
-+			       pr_crit(
-+			       "BFQ WARNING:last %lu budget %lu jiffies %lu",
-+			       bfqq->last_wr_start_finish,
-+			       bfqq->budget_timeout,
-+			       jiffies);
-+			       pr_crit("diff %lu", jiffies -
-+				       max_t(unsigned long,
-+					     bfqq->last_wr_start_finish,
-+					     bfqq->budget_timeout));
-+			       bfqq->last_wr_start_finish = jiffies;
-+			}
-+		}
-+
-+		bfq_set_budget_timeout(bfqd, bfqq);
-+		bfq_log_bfqq(bfqd, bfqq,
-+			     "cur-budget = %d prio_class %d",
-+			     bfqq->entity.budget, bfqq->ioprio_class);
-+	} else
-+		bfq_log(bfqd, "NULL");
-+
-+	bfqd->in_service_queue = bfqq;
-+}
-+
-+/*
-+ * Get and set a new queue for service.
-+ */
-+static struct bfq_queue *bfq_set_in_service_queue(struct bfq_data *bfqd)
-+{
-+	struct bfq_queue *bfqq = bfq_get_next_queue(bfqd);
-+
-+	__bfq_set_in_service_queue(bfqd, bfqq);
-+	return bfqq;
-+}
-+
-+static void bfq_arm_slice_timer(struct bfq_data *bfqd)
-+{
-+	struct bfq_queue *bfqq = bfqd->in_service_queue;
-+	struct bfq_io_cq *bic;
-+	u32 sl;
-+
-+	BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list));
-+
-+	/* Processes have exited, don't wait. */
-+	bic = bfqd->in_service_bic;
-+	if (!bic || atomic_read(&bic->icq.ioc->active_ref) == 0)
-+		return;
-+
-+	bfq_mark_bfqq_wait_request(bfqq);
-+
-+	/*
-+	 * We don't want to idle for seeks, but we do want to allow
-+	 * fair distribution of slice time for a process doing back-to-back
-+	 * seeks. So allow a little bit of time for him to submit a new rq.
-+	 *
-+	 * To prevent processes with (partly) seeky workloads from
-+	 * being too ill-treated, grant them a small fraction of the
-+	 * assigned budget before reducing the waiting time to
-+	 * BFQ_MIN_TT. This happened to help reduce latency.
-+	 */
-+	sl = bfqd->bfq_slice_idle;
-+	/*
-+	 * Unless the queue is being weight-raised or the scenario is
-+	 * asymmetric, grant only minimum idle time if the queue
-+	 * is seeky. A long idling is preserved for a weight-raised
-+	 * queue, or, more in general, in an asymemtric scenario,
-+	 * because a long idling is needed for guaranteeing to a queue
-+	 * its reserved share of the throughput (in particular, it is
-+	 * needed if the queue has a higher weight than some other
-+	 * queue).
-+	 */
-+	if (BFQQ_SEEKY(bfqq) && bfqq->wr_coeff == 1 &&
-+	    bfq_symmetric_scenario(bfqd))
-+		sl = min_t(u32, sl, BFQ_MIN_TT);
-+
-+	bfqd->last_idling_start = ktime_get();
-+	hrtimer_start(&bfqd->idle_slice_timer, ns_to_ktime(sl),
-+		      HRTIMER_MODE_REL);
-+	bfqg_stats_set_start_idle_time(bfqq_group(bfqq));
-+	bfq_log(bfqd, "arm idle: %ld/%ld ms",
-+		sl / NSEC_PER_MSEC, bfqd->bfq_slice_idle / NSEC_PER_MSEC);
-+}
-+
-+/*
-+ * In autotuning mode, max_budget is dynamically recomputed as the
-+ * amount of sectors transferred in timeout at the estimated peak
-+ * rate. This enables BFQ to utilize a full timeslice with a full
-+ * budget, even if the in-service queue is served at peak rate. And
-+ * this maximises throughput with sequential workloads.
-+ */
-+static unsigned long bfq_calc_max_budget(struct bfq_data *bfqd)
-+{
-+	return (u64)bfqd->peak_rate * USEC_PER_MSEC *
-+		jiffies_to_msecs(bfqd->bfq_timeout)>>BFQ_RATE_SHIFT;
-+}
-+
-+/*
-+ * Update parameters related to throughput and responsiveness, as a
-+ * function of the estimated peak rate. See comments on
-+ * bfq_calc_max_budget(), and on the ref_wr_duration array.
-+ */
-+static void update_thr_responsiveness_params(struct bfq_data *bfqd)
-+{
-+	if (bfqd->bfq_user_max_budget == 0) {
-+		bfqd->bfq_max_budget =
-+			bfq_calc_max_budget(bfqd);
-+		BUG_ON(bfqd->bfq_max_budget < 0);
-+		bfq_log(bfqd, "new max_budget = %d",
-+			bfqd->bfq_max_budget);
-+	}
-+}
-+
-+static void bfq_reset_rate_computation(struct bfq_data *bfqd, struct request *rq)
-+{
-+	if (rq != NULL) { /* new rq dispatch now, reset accordingly */
-+		bfqd->last_dispatch = bfqd->first_dispatch = ktime_get_ns() ;
-+		bfqd->peak_rate_samples = 1;
-+		bfqd->sequential_samples = 0;
-+		bfqd->tot_sectors_dispatched = bfqd->last_rq_max_size =
-+			blk_rq_sectors(rq);
-+	} else /* no new rq dispatched, just reset the number of samples */
-+		bfqd->peak_rate_samples = 0; /* full re-init on next disp. */
-+
-+	bfq_log(bfqd,
-+		"at end, sample %u/%u tot_sects %llu",
-+		bfqd->peak_rate_samples, bfqd->sequential_samples,
-+		bfqd->tot_sectors_dispatched);
-+}
-+
-+static void bfq_update_rate_reset(struct bfq_data *bfqd, struct request *rq)
-+{
-+	u32 rate, weight, divisor;
-+
-+	/*
-+	 * For the convergence property to hold (see comments on
-+	 * bfq_update_peak_rate()) and for the assessment to be
-+	 * reliable, a minimum number of samples must be present, and
-+	 * a minimum amount of time must have elapsed. If not so, do
-+	 * not compute new rate. Just reset parameters, to get ready
-+	 * for a new evaluation attempt.
-+	 */
-+	if (bfqd->peak_rate_samples < BFQ_RATE_MIN_SAMPLES ||
-+	    bfqd->delta_from_first < BFQ_RATE_MIN_INTERVAL) {
-+		bfq_log(bfqd,
-+	"only resetting, delta_first %lluus samples %d",
-+			bfqd->delta_from_first>>10, bfqd->peak_rate_samples);
-+		goto reset_computation;
-+	}
-+
-+	/*
-+	 * If a new request completion has occurred after last
-+	 * dispatch, then, to approximate the rate at which requests
-+	 * have been served by the device, it is more precise to
-+	 * extend the observation interval to the last completion.
-+	 */
-+	bfqd->delta_from_first =
-+		max_t(u64, bfqd->delta_from_first,
-+		      bfqd->last_completion - bfqd->first_dispatch);
-+
-+	BUG_ON(bfqd->delta_from_first == 0);
-+	/*
-+	 * Rate computed in sects/usec, and not sects/nsec, for
-+	 * precision issues.
-+	 */
-+	rate = div64_ul(bfqd->tot_sectors_dispatched<<BFQ_RATE_SHIFT,
-+			div_u64(bfqd->delta_from_first, NSEC_PER_USEC));
-+
-+	bfq_log(bfqd,
-+"tot_sects %llu delta_first %lluus rate %llu sects/s (%d)",
-+		bfqd->tot_sectors_dispatched, bfqd->delta_from_first>>10,
-+		((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT),
-+		rate > 20<<BFQ_RATE_SHIFT);
-+
-+	/*
-+	 * Peak rate not updated if:
-+	 * - the percentage of sequential dispatches is below 3/4 of the
-+	 *   total, and rate is below the current estimated peak rate
-+	 * - rate is unreasonably high (> 20M sectors/sec)
-+	 */
-+	if ((bfqd->sequential_samples < (3 * bfqd->peak_rate_samples)>>2 &&
-+	     rate <= bfqd->peak_rate) ||
-+		rate > 20<<BFQ_RATE_SHIFT) {
-+		bfq_log(bfqd,
-+		"goto reset, samples %u/%u rate/peak %llu/%llu",
-+		bfqd->peak_rate_samples, bfqd->sequential_samples,
-+		((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT),
-+		((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT));
-+		goto reset_computation;
-+	} else {
-+		bfq_log(bfqd,
-+		"do update, samples %u/%u rate/peak %llu/%llu",
-+		bfqd->peak_rate_samples, bfqd->sequential_samples,
-+		((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT),
-+		((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT));
-+	}
-+
-+	/*
-+	 * We have to update the peak rate, at last! To this purpose,
-+	 * we use a low-pass filter. We compute the smoothing constant
-+	 * of the filter as a function of the 'weight' of the new
-+	 * measured rate.
-+	 *
-+	 * As can be seen in next formulas, we define this weight as a
-+	 * quantity proportional to how sequential the workload is,
-+	 * and to how long the observation time interval is.
-+	 *
-+	 * The weight runs from 0 to 8. The maximum value of the
-+	 * weight, 8, yields the minimum value for the smoothing
-+	 * constant. At this minimum value for the smoothing constant,
-+	 * the measured rate contributes for half of the next value of
-+	 * the estimated peak rate.
-+	 *
-+	 * So, the first step is to compute the weight as a function
-+	 * of how sequential the workload is. Note that the weight
-+	 * cannot reach 9, because bfqd->sequential_samples cannot
-+	 * become equal to bfqd->peak_rate_samples, which, in its
-+	 * turn, holds true because bfqd->sequential_samples is not
-+	 * incremented for the first sample.
-+	 */
-+	weight = (9 * bfqd->sequential_samples) / bfqd->peak_rate_samples;
-+
-+	/*
-+	 * Second step: further refine the weight as a function of the
-+	 * duration of the observation interval.
-+	 */
-+	weight = min_t(u32, 8,
-+		       div_u64(weight * bfqd->delta_from_first,
-+			       BFQ_RATE_REF_INTERVAL));
-+
-+	/*
-+	 * Divisor ranging from 10, for minimum weight, to 2, for
-+	 * maximum weight.
-+	 */
-+	divisor = 10 - weight;
-+	BUG_ON(divisor == 0);
-+
-+	/*
-+	 * Finally, update peak rate:
-+	 *
-+	 * peak_rate = peak_rate * (divisor-1) / divisor  +  rate / divisor
-+	 */
-+	bfqd->peak_rate *= divisor-1;
-+	bfqd->peak_rate /= divisor;
-+	rate /= divisor; /* smoothing constant alpha = 1/divisor */
-+
-+	bfq_log(bfqd,
-+		"divisor %d tmp_peak_rate %llu tmp_rate %u",
-+		divisor,
-+		((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT),
-+		(u32)((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT));
-+
-+	BUG_ON(bfqd->peak_rate == 0);
-+	BUG_ON(bfqd->peak_rate > 20<<BFQ_RATE_SHIFT);
-+
-+	bfqd->peak_rate += rate;
-+
-+	/*
-+	 * For a very slow device, bfqd->peak_rate can reach 0 (see
-+	 * the minimum representable values reported in the comments
-+	 * on BFQ_RATE_SHIFT). Push to 1 if this happens, to avoid
-+	 * divisions by zero where bfqd->peak_rate is used as a
-+	 * divisor.
-+	 */
-+	bfqd->peak_rate = max_t(u32, 1, bfqd->peak_rate);
-+
-+	update_thr_responsiveness_params(bfqd);
-+	BUG_ON(bfqd->peak_rate > 20<<BFQ_RATE_SHIFT);
-+
-+reset_computation:
-+	bfq_reset_rate_computation(bfqd, rq);
-+}
-+
-+/*
-+ * Update the read/write peak rate (the main quantity used for
-+ * auto-tuning, see update_thr_responsiveness_params()).
-+ *
-+ * It is not trivial to estimate the peak rate (correctly): because of
-+ * the presence of sw and hw queues between the scheduler and the
-+ * device components that finally serve I/O requests, it is hard to
-+ * say exactly when a given dispatched request is served inside the
-+ * device, and for how long. As a consequence, it is hard to know
-+ * precisely at what rate a given set of requests is actually served
-+ * by the device.
-+ *
-+ * On the opposite end, the dispatch time of any request is trivially
-+ * available, and, from this piece of information, the "dispatch rate"
-+ * of requests can be immediately computed. So, the idea in the next
-+ * function is to use what is known, namely request dispatch times
-+ * (plus, when useful, request completion times), to estimate what is
-+ * unknown, namely in-device request service rate.
-+ *
-+ * The main issue is that, because of the above facts, the rate at
-+ * which a certain set of requests is dispatched over a certain time
-+ * interval can vary greatly with respect to the rate at which the
-+ * same requests are then served. But, since the size of any
-+ * intermediate queue is limited, and the service scheme is lossless
-+ * (no request is silently dropped), the following obvious convergence
-+ * property holds: the number of requests dispatched MUST become
-+ * closer and closer to the number of requests completed as the
-+ * observation interval grows. This is the key property used in
-+ * the next function to estimate the peak service rate as a function
-+ * of the observed dispatch rate. The function assumes to be invoked
-+ * on every request dispatch.
-+ */
-+static void bfq_update_peak_rate(struct bfq_data *bfqd, struct request *rq)
-+{
-+	u64 now_ns = ktime_get_ns();
-+
-+	if (bfqd->peak_rate_samples == 0) { /* first dispatch */
-+		bfq_log(bfqd,
-+		"goto reset, samples %d",
-+				bfqd->peak_rate_samples) ;
-+		bfq_reset_rate_computation(bfqd, rq);
-+		goto update_last_values; /* will add one sample */
-+	}
-+
-+	/*
-+	 * Device idle for very long: the observation interval lasting
-+	 * up to this dispatch cannot be a valid observation interval
-+	 * for computing a new peak rate (similarly to the late-
-+	 * completion event in bfq_completed_request()). Go to
-+	 * update_rate_and_reset to have the following three steps
-+	 * taken:
-+	 * - close the observation interval at the last (previous)
-+	 *   request dispatch or completion
-+	 * - compute rate, if possible, for that observation interval
-+	 * - start a new observation interval with this dispatch
-+	 */
-+	if (now_ns - bfqd->last_dispatch > 100*NSEC_PER_MSEC &&
-+	    bfqd->rq_in_driver == 0) {
-+		bfq_log(bfqd,
-+"jumping to updating&resetting delta_last %lluus samples %d",
-+			(now_ns - bfqd->last_dispatch)>>10,
-+			bfqd->peak_rate_samples) ;
-+		goto update_rate_and_reset;
-+	}
-+
-+	/* Update sampling information */
-+	bfqd->peak_rate_samples++;
-+
-+	if ((bfqd->rq_in_driver > 0 ||
-+		now_ns - bfqd->last_completion < BFQ_MIN_TT)
-+	    && !BFQ_RQ_SEEKY(bfqd, bfqd->last_position, rq))
-+		bfqd->sequential_samples++;
-+
-+	bfqd->tot_sectors_dispatched += blk_rq_sectors(rq);
-+
-+	/* Reset max observed rq size every 32 dispatches */
-+	if (likely(bfqd->peak_rate_samples % 32))
-+		bfqd->last_rq_max_size =
-+			max_t(u32, blk_rq_sectors(rq), bfqd->last_rq_max_size);
-+	else
-+		bfqd->last_rq_max_size = blk_rq_sectors(rq);
-+
-+	bfqd->delta_from_first = now_ns - bfqd->first_dispatch;
-+
-+	bfq_log(bfqd,
-+	"added samples %u/%u tot_sects %llu delta_first %lluus",
-+		bfqd->peak_rate_samples, bfqd->sequential_samples,
-+		bfqd->tot_sectors_dispatched,
-+		bfqd->delta_from_first>>10);
-+
-+	/* Target observation interval not yet reached, go on sampling */
-+	if (bfqd->delta_from_first < BFQ_RATE_REF_INTERVAL)
-+		goto update_last_values;
-+
-+update_rate_and_reset:
-+	bfq_update_rate_reset(bfqd, rq);
-+update_last_values:
-+	bfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
-+	if (RQ_BFQQ(rq) == bfqd->in_service_queue)
-+		bfqd->in_serv_last_pos = bfqd->last_position;
-+	bfqd->last_dispatch = now_ns;
-+
-+	bfq_log(bfqd,
-+	"delta_first %lluus last_pos %llu peak_rate %llu",
-+		(now_ns - bfqd->first_dispatch)>>10,
-+		(unsigned long long) bfqd->last_position,
-+		((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT));
-+	bfq_log(bfqd,
-+	"samples at end %d", bfqd->peak_rate_samples);
-+}
-+
-+/*
-+ * Move request from internal lists to the dispatch list of the request queue
-+ */
-+static void bfq_dispatch_insert(struct request_queue *q, struct request *rq)
-+{
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq);
-+
-+	/*
-+	 * For consistency, the next instruction should have been executed
-+	 * after removing the request from the queue and dispatching it.
-+	 * We execute instead this instruction before bfq_remove_request()
-+	 * (and hence introduce a temporary inconsistency), for efficiency.
-+	 * In fact, in a forced_dispatch, this prevents two counters related
-+	 * to bfqq->dispatched to risk to be uselessly decremented if bfqq
-+	 * is not in service, and then to be incremented again after
-+	 * incrementing bfqq->dispatched.
-+	 */
-+	bfqq->dispatched++;
-+	bfq_update_peak_rate(q->elevator->elevator_data, rq);
-+
-+	bfq_remove_request(rq);
-+	elv_dispatch_sort(q, rq);
-+}
-+
-+static void __bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	BUG_ON(bfqq != bfqd->in_service_queue);
-+
-+	/*
-+	 * If this bfqq is shared between multiple processes, check
-+	 * to make sure that those processes are still issuing I/Os
-+	 * within the mean seek distance. If not, it may be time to
-+	 * break the queues apart again.
-+	 */
-+	if (bfq_bfqq_coop(bfqq) && BFQQ_SEEKY(bfqq))
-+		bfq_mark_bfqq_split_coop(bfqq);
-+
-+	if (RB_EMPTY_ROOT(&bfqq->sort_list)) {
-+		if (bfqq->dispatched == 0)
-+			/*
-+			 * Overloading budget_timeout field to store
-+			 * the time at which the queue remains with no
-+			 * backlog and no outstanding request; used by
-+			 * the weight-raising mechanism.
-+			 */
-+			bfqq->budget_timeout = jiffies;
-+
-+		bfq_del_bfqq_busy(bfqd, bfqq, true);
-+	} else {
-+		bfq_requeue_bfqq(bfqd, bfqq, true);
-+		/*
-+		 * Resort priority tree of potential close cooperators.
-+		 */
-+		bfq_pos_tree_add_move(bfqd, bfqq);
-+	}
-+
-+	/*
-+	 * All in-service entities must have been properly deactivated
-+	 * or requeued before executing the next function, which
-+	 * resets all in-service entites as no more in service.
-+	 */
-+	__bfq_bfqd_reset_in_service(bfqd);
-+}
-+
-+/**
-+ * __bfq_bfqq_recalc_budget - try to adapt the budget to the @bfqq behavior.
-+ * @bfqd: device data.
-+ * @bfqq: queue to update.
-+ * @reason: reason for expiration.
-+ *
-+ * Handle the feedback on @bfqq budget at queue expiration.
-+ * See the body for detailed comments.
-+ */
-+static void __bfq_bfqq_recalc_budget(struct bfq_data *bfqd,
-+				     struct bfq_queue *bfqq,
-+				     enum bfqq_expiration reason)
-+{
-+	struct request *next_rq;
-+	int budget, min_budget;
-+
-+	BUG_ON(bfqq != bfqd->in_service_queue);
-+
-+	min_budget = bfq_min_budget(bfqd);
-+
-+	if (bfqq->wr_coeff == 1)
-+		budget = bfqq->max_budget;
-+	else /*
-+	      * Use a constant, low budget for weight-raised queues,
-+	      * to help achieve a low latency. Keep it slightly higher
-+	      * than the minimum possible budget, to cause a little
-+	      * bit fewer expirations.
-+	      */
-+		budget = 2 * min_budget;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "last budg %d, budg left %d",
-+		bfqq->entity.budget, bfq_bfqq_budget_left(bfqq));
-+	bfq_log_bfqq(bfqd, bfqq, "last max_budg %d, min budg %d",
-+		budget, bfq_min_budget(bfqd));
-+	bfq_log_bfqq(bfqd, bfqq, "sync %d, seeky %d",
-+		bfq_bfqq_sync(bfqq), BFQQ_SEEKY(bfqd->in_service_queue));
-+
-+	if (bfq_bfqq_sync(bfqq) && bfqq->wr_coeff == 1) {
-+		switch (reason) {
-+		/*
-+		 * Caveat: in all the following cases we trade latency
-+		 * for throughput.
-+		 */
-+		case BFQ_BFQQ_TOO_IDLE:
-+			/*
-+			 * This is the only case where we may reduce
-+			 * the budget: if there is no request of the
-+			 * process still waiting for completion, then
-+			 * we assume (tentatively) that the timer has
-+			 * expired because the batch of requests of
-+			 * the process could have been served with a
-+			 * smaller budget.  Hence, betting that
-+			 * process will behave in the same way when it
-+			 * becomes backlogged again, we reduce its
-+			 * next budget.  As long as we guess right,
-+			 * this budget cut reduces the latency
-+			 * experienced by the process.
-+			 *
-+			 * However, if there are still outstanding
-+			 * requests, then the process may have not yet
-+			 * issued its next request just because it is
-+			 * still waiting for the completion of some of
-+			 * the still outstanding ones.  So in this
-+			 * subcase we do not reduce its budget, on the
-+			 * contrary we increase it to possibly boost
-+			 * the throughput, as discussed in the
-+			 * comments to the BUDGET_TIMEOUT case.
-+			 */
-+			if (bfqq->dispatched > 0) /* still outstanding reqs */
-+				budget = min(budget * 2, bfqd->bfq_max_budget);
-+			else {
-+				if (budget > 5 * min_budget)
-+					budget -= 4 * min_budget;
-+				else
-+					budget = min_budget;
-+			}
-+			break;
-+		case BFQ_BFQQ_BUDGET_TIMEOUT:
-+			/*
-+			 * We double the budget here because it gives
-+			 * the chance to boost the throughput if this
-+			 * is not a seeky process (and has bumped into
-+			 * this timeout because of, e.g., ZBR).
-+			 */
-+			budget = min(budget * 2, bfqd->bfq_max_budget);
-+			break;
-+		case BFQ_BFQQ_BUDGET_EXHAUSTED:
-+			/*
-+			 * The process still has backlog, and did not
-+			 * let either the budget timeout or the disk
-+			 * idling timeout expire. Hence it is not
-+			 * seeky, has a short thinktime and may be
-+			 * happy with a higher budget too. So
-+			 * definitely increase the budget of this good
-+			 * candidate to boost the disk throughput.
-+			 */
-+			budget = min(budget * 4, bfqd->bfq_max_budget);
-+			break;
-+		case BFQ_BFQQ_NO_MORE_REQUESTS:
-+			/*
-+			 * For queues that expire for this reason, it
-+			 * is particularly important to keep the
-+			 * budget close to the actual service they
-+			 * need. Doing so reduces the timestamp
-+			 * misalignment problem described in the
-+			 * comments in the body of
-+			 * __bfq_activate_entity. In fact, suppose
-+			 * that a queue systematically expires for
-+			 * BFQ_BFQQ_NO_MORE_REQUESTS and presents a
-+			 * new request in time to enjoy timestamp
-+			 * back-shifting. The larger the budget of the
-+			 * queue is with respect to the service the
-+			 * queue actually requests in each service
-+			 * slot, the more times the queue can be
-+			 * reactivated with the same virtual finish
-+			 * time. It follows that, even if this finish
-+			 * time is pushed to the system virtual time
-+			 * to reduce the consequent timestamp
-+			 * misalignment, the queue unjustly enjoys for
-+			 * many re-activations a lower finish time
-+			 * than all newly activated queues.
-+			 *
-+			 * The service needed by bfqq is measured
-+			 * quite precisely by bfqq->entity.service.
-+			 * Since bfqq does not enjoy device idling,
-+			 * bfqq->entity.service is equal to the number
-+			 * of sectors that the process associated with
-+			 * bfqq requested to read/write before waiting
-+			 * for request completions, or blocking for
-+			 * other reasons.
-+			 */
-+			budget = max_t(int, bfqq->entity.service, min_budget);
-+			break;
-+		default:
-+			return;
-+		}
-+	} else if (!bfq_bfqq_sync(bfqq))
-+		/*
-+		 * Async queues get always the maximum possible
-+		 * budget, as for them we do not care about latency
-+		 * (in addition, their ability to dispatch is limited
-+		 * by the charging factor).
-+		 */
-+		budget = bfqd->bfq_max_budget;
-+
-+	bfqq->max_budget = budget;
-+
-+	if (bfqd->budgets_assigned >= bfq_stats_min_budgets &&
-+	    !bfqd->bfq_user_max_budget)
-+		bfqq->max_budget = min(bfqq->max_budget, bfqd->bfq_max_budget);
-+
-+	/*
-+	 * If there is still backlog, then assign a new budget, making
-+	 * sure that it is large enough for the next request.  Since
-+	 * the finish time of bfqq must be kept in sync with the
-+	 * budget, be sure to call __bfq_bfqq_expire() *after* this
-+	 * update.
-+	 *
-+	 * If there is no backlog, then no need to update the budget;
-+	 * it will be updated on the arrival of a new request.
-+	 */
-+	next_rq = bfqq->next_rq;
-+	if (next_rq) {
-+		BUG_ON(reason == BFQ_BFQQ_TOO_IDLE ||
-+		       reason == BFQ_BFQQ_NO_MORE_REQUESTS);
-+		bfqq->entity.budget = max_t(unsigned long, bfqq->max_budget,
-+					    bfq_serv_to_charge(next_rq, bfqq));
-+		BUG_ON(!bfq_bfqq_busy(bfqq));
-+		BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list));
-+	}
-+
-+	bfq_log_bfqq(bfqd, bfqq, "head sect: %u, new budget %d",
-+			next_rq ? blk_rq_sectors(next_rq) : 0,
-+			bfqq->entity.budget);
-+}
-+
-+/*
-+ * Return true if the process associated with bfqq is "slow". The slow
-+ * flag is used, in addition to the budget timeout, to reduce the
-+ * amount of service provided to seeky processes, and thus reduce
-+ * their chances to lower the throughput. More details in the comments
-+ * on the function bfq_bfqq_expire().
-+ *
-+ * An important observation is in order: as discussed in the comments
-+ * on the function bfq_update_peak_rate(), with devices with internal
-+ * queues, it is hard if ever possible to know when and for how long
-+ * an I/O request is processed by the device (apart from the trivial
-+ * I/O pattern where a new request is dispatched only after the
-+ * previous one has been completed). This makes it hard to evaluate
-+ * the real rate at which the I/O requests of each bfq_queue are
-+ * served.  In fact, for an I/O scheduler like BFQ, serving a
-+ * bfq_queue means just dispatching its requests during its service
-+ * slot (i.e., until the budget of the queue is exhausted, or the
-+ * queue remains idle, or, finally, a timeout fires). But, during the
-+ * service slot of a bfq_queue, around 100 ms at most, the device may
-+ * be even still processing requests of bfq_queues served in previous
-+ * service slots. On the opposite end, the requests of the in-service
-+ * bfq_queue may be completed after the service slot of the queue
-+ * finishes.
-+ *
-+ * Anyway, unless more sophisticated solutions are used
-+ * (where possible), the sum of the sizes of the requests dispatched
-+ * during the service slot of a bfq_queue is probably the only
-+ * approximation available for the service received by the bfq_queue
-+ * during its service slot. And this sum is the quantity used in this
-+ * function to evaluate the I/O speed of a process.
-+ */
-+static bool bfq_bfqq_is_slow(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+				 bool compensate, enum bfqq_expiration reason,
-+				 unsigned long *delta_ms)
-+{
-+	ktime_t delta_ktime;
-+	u32 delta_usecs;
-+	bool slow = BFQQ_SEEKY(bfqq); /* if delta too short, use seekyness */
-+
-+	if (!bfq_bfqq_sync(bfqq))
-+		return false;
-+
-+	if (compensate)
-+		delta_ktime = bfqd->last_idling_start;
-+	else
-+		delta_ktime = ktime_get();
-+	delta_ktime = ktime_sub(delta_ktime, bfqd->last_budget_start);
-+	delta_usecs = ktime_to_us(delta_ktime);
-+
-+	/* don't use too short time intervals */
-+	if (delta_usecs < 1000) {
-+		if (blk_queue_nonrot(bfqd->queue))
-+			 /*
-+			  * give same worst-case guarantees as idling
-+			  * for seeky
-+			  */
-+			*delta_ms = BFQ_MIN_TT / NSEC_PER_MSEC;
-+		else /* charge at least one seek */
-+			*delta_ms = bfq_slice_idle / NSEC_PER_MSEC;
-+
-+		bfq_log(bfqd, "too short %u", delta_usecs);
-+
-+		return slow;
-+	}
-+
-+	*delta_ms = delta_usecs / USEC_PER_MSEC;
-+
-+	/*
-+	 * Use only long (> 20ms) intervals to filter out excessive
-+	 * spikes in service rate estimation.
-+	 */
-+	if (delta_usecs > 20000) {
-+		/*
-+		 * Caveat for rotational devices: processes doing I/O
-+		 * in the slower disk zones tend to be slow(er) even
-+		 * if not seeky. In this respect, the estimated peak
-+		 * rate is likely to be an average over the disk
-+		 * surface. Accordingly, to not be too harsh with
-+		 * unlucky processes, a process is deemed slow only if
-+		 * its rate has been lower than half of the estimated
-+		 * peak rate.
-+		 */
-+		slow = bfqq->entity.service < bfqd->bfq_max_budget / 2;
-+		bfq_log(bfqd, "relative rate %d/%d",
-+			bfqq->entity.service, bfqd->bfq_max_budget);
-+	}
-+
-+	bfq_log_bfqq(bfqd, bfqq, "slow %d", slow);
-+
-+	return slow;
-+}
-+
-+/*
-+ * To be deemed as soft real-time, an application must meet two
-+ * requirements. First, the application must not require an average
-+ * bandwidth higher than the approximate bandwidth required to playback or
-+ * record a compressed high-definition video.
-+ * The next function is invoked on the completion of the last request of a
-+ * batch, to compute the next-start time instant, soft_rt_next_start, such
-+ * that, if the next request of the application does not arrive before
-+ * soft_rt_next_start, then the above requirement on the bandwidth is met.
-+ *
-+ * The second requirement is that the request pattern of the application is
-+ * isochronous, i.e., that, after issuing a request or a batch of requests,
-+ * the application stops issuing new requests until all its pending requests
-+ * have been completed. After that, the application may issue a new batch,
-+ * and so on.
-+ * For this reason the next function is invoked to compute
-+ * soft_rt_next_start only for applications that meet this requirement,
-+ * whereas soft_rt_next_start is set to infinity for applications that do
-+ * not.
-+ *
-+ * Unfortunately, even a greedy (i.e., I/O-bound) application may
-+ * happen to meet, occasionally or systematically, both the above
-+ * bandwidth and isochrony requirements. This may happen at least in
-+ * the following circumstances. First, if the CPU load is high. The
-+ * application may stop issuing requests while the CPUs are busy
-+ * serving other processes, then restart, then stop again for a while,
-+ * and so on. The other circumstances are related to the storage
-+ * device: the storage device is highly loaded or reaches a low-enough
-+ * throughput with the I/O of the application (e.g., because the I/O
-+ * is random and/or the device is slow). In all these cases, the
-+ * I/O of the application may be simply slowed down enough to meet
-+ * the bandwidth and isochrony requirements. To reduce the probability
-+ * that greedy applications are deemed as soft real-time in these
-+ * corner cases, a further rule is used in the computation of
-+ * soft_rt_next_start: the return value of this function is forced to
-+ * be higher than the maximum between the following two quantities.
-+ *
-+ * (a) Current time plus: (1) the maximum time for which the arrival
-+ *     of a request is waited for when a sync queue becomes idle,
-+ *     namely bfqd->bfq_slice_idle, and (2) a few extra jiffies. We
-+ *     postpone for a moment the reason for adding a few extra
-+ *     jiffies; we get back to it after next item (b).  Lower-bounding
-+ *     the return value of this function with the current time plus
-+ *     bfqd->bfq_slice_idle tends to filter out greedy applications,
-+ *     because the latter issue their next request as soon as possible
-+ *     after the last one has been completed. In contrast, a soft
-+ *     real-time application spends some time processing data, after a
-+ *     batch of its requests has been completed.
-+ *
-+ * (b) Current value of bfqq->soft_rt_next_start. As pointed out
-+ *     above, greedy applications may happen to meet both the
-+ *     bandwidth and isochrony requirements under heavy CPU or
-+ *     storage-device load. In more detail, in these scenarios, these
-+ *     applications happen, only for limited time periods, to do I/O
-+ *     slowly enough to meet all the requirements described so far,
-+ *     including the filtering in above item (a). These slow-speed
-+ *     time intervals are usually interspersed between other time
-+ *     intervals during which these applications do I/O at a very high
-+ *     speed. Fortunately, exactly because of the high speed of the
-+ *     I/O in the high-speed intervals, the values returned by this
-+ *     function happen to be so high, near the end of any such
-+ *     high-speed interval, to be likely to fall *after* the end of
-+ *     the low-speed time interval that follows. These high values are
-+ *     stored in bfqq->soft_rt_next_start after each invocation of
-+ *     this function. As a consequence, if the last value of
-+ *     bfqq->soft_rt_next_start is constantly used to lower-bound the
-+ *     next value that this function may return, then, from the very
-+ *     beginning of a low-speed interval, bfqq->soft_rt_next_start is
-+ *     likely to be constantly kept so high that any I/O request
-+ *     issued during the low-speed interval is considered as arriving
-+ *     to soon for the application to be deemed as soft
-+ *     real-time. Then, in the high-speed interval that follows, the
-+ *     application will not be deemed as soft real-time, just because
-+ *     it will do I/O at a high speed. And so on.
-+ *
-+ * Getting back to the filtering in item (a), in the following two
-+ * cases this filtering might be easily passed by a greedy
-+ * application, if the reference quantity was just
-+ * bfqd->bfq_slice_idle:
-+ * 1) HZ is so low that the duration of a jiffy is comparable to or
-+ *    higher than bfqd->bfq_slice_idle. This happens, e.g., on slow
-+ *    devices with HZ=100. The time granularity may be so coarse
-+ *    that the approximation, in jiffies, of bfqd->bfq_slice_idle
-+ *    is rather lower than the exact value.
-+ * 2) jiffies, instead of increasing at a constant rate, may stop increasing
-+ *    for a while, then suddenly 'jump' by several units to recover the lost
-+ *    increments. This seems to happen, e.g., inside virtual machines.
-+ * To address this issue, in the filtering in (a) we do not use as a
-+ * reference time interval just bfqd->bfq_slice_idle, but
-+ * bfqd->bfq_slice_idle plus a few jiffies. In particular, we add the
-+ * minimum number of jiffies for which the filter seems to be quite
-+ * precise also in embedded systems and KVM/QEMU virtual machines.
-+ */
-+static unsigned long bfq_bfqq_softrt_next_start(struct bfq_data *bfqd,
-+						struct bfq_queue *bfqq)
-+{
-+	bfq_log_bfqq(bfqd, bfqq,
-+"service_blkg %lu soft_rate %u sects/sec interval %u",
-+		     bfqq->service_from_backlogged,
-+		     bfqd->bfq_wr_max_softrt_rate,
-+		     jiffies_to_msecs(HZ * bfqq->service_from_backlogged /
-+				      bfqd->bfq_wr_max_softrt_rate));
-+
-+	return max3(bfqq->soft_rt_next_start,
-+		    bfqq->last_idle_bklogged +
-+		    HZ * bfqq->service_from_backlogged /
-+		    bfqd->bfq_wr_max_softrt_rate,
-+		    jiffies + nsecs_to_jiffies(bfqq->bfqd->bfq_slice_idle) + 4);
-+}
-+
-+static bool bfq_bfqq_injectable(struct bfq_queue *bfqq)
-+{
-+	return BFQQ_SEEKY(bfqq) && bfqq->wr_coeff == 1 &&
-+		blk_queue_nonrot(bfqq->bfqd->queue) &&
-+		bfqq->bfqd->hw_tag;
-+}
-+
-+/**
-+ * bfq_bfqq_expire - expire a queue.
-+ * @bfqd: device owning the queue.
-+ * @bfqq: the queue to expire.
-+ * @compensate: if true, compensate for the time spent idling.
-+ * @reason: the reason causing the expiration.
-+ *
-+ * If the process associated with bfqq does slow I/O (e.g., because it
-+ * issues random requests), we charge bfqq with the time it has been
-+ * in service instead of the service it has received (see
-+ * bfq_bfqq_charge_time for details on how this goal is achieved). As
-+ * a consequence, bfqq will typically get higher timestamps upon
-+ * reactivation, and hence it will be rescheduled as if it had
-+ * received more service than what it has actually received. In the
-+ * end, bfqq receives less service in proportion to how slowly its
-+ * associated process consumes its budgets (and hence how seriously it
-+ * tends to lower the throughput). In addition, this time-charging
-+ * strategy guarantees time fairness among slow processes. In
-+ * contrast, if the process associated with bfqq is not slow, we
-+ * charge bfqq exactly with the service it has received.
-+ *
-+ * Charging time to the first type of queues and the exact service to
-+ * the other has the effect of using the WF2Q+ policy to schedule the
-+ * former on a timeslice basis, without violating service domain
-+ * guarantees among the latter.
-+ */
-+static void bfq_bfqq_expire(struct bfq_data *bfqd,
-+			    struct bfq_queue *bfqq,
-+			    bool compensate,
-+			    enum bfqq_expiration reason)
-+{
-+	bool slow;
-+	unsigned long delta = 0;
-+	struct bfq_entity *entity = &bfqq->entity;
-+	int ref;
-+
-+	BUG_ON(bfqq != bfqd->in_service_queue);
-+
-+	/*
-+	 * Check whether the process is slow (see bfq_bfqq_is_slow).
-+	 */
-+	slow = bfq_bfqq_is_slow(bfqd, bfqq, compensate, reason, &delta);
-+
-+	/*
-+	 * As above explained, charge slow (typically seeky) and
-+	 * timed-out queues with the time and not the service
-+	 * received, to favor sequential workloads.
-+	 *
-+	 * Processes doing I/O in the slower disk zones will tend to
-+	 * be slow(er) even if not seeky. Therefore, since the
-+	 * estimated peak rate is actually an average over the disk
-+	 * surface, these processes may timeout just for bad luck. To
-+	 * avoid punishing them, do not charge time to processes that
-+	 * succeeded in consuming at least 2/3 of their budget. This
-+	 * allows BFQ to preserve enough elasticity to still perform
-+	 * bandwidth, and not time, distribution with little unlucky
-+	 * or quasi-sequential processes.
-+	 */
-+	if (bfqq->wr_coeff == 1 &&
-+	    (slow ||
-+	     (reason == BFQ_BFQQ_BUDGET_TIMEOUT &&
-+	      bfq_bfqq_budget_left(bfqq) >=  entity->budget / 3)))
-+		bfq_bfqq_charge_time(bfqd, bfqq, delta);
-+
-+	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
-+
-+	if (reason == BFQ_BFQQ_TOO_IDLE &&
-+	    entity->service <= 2 * entity->budget / 10)
-+		bfq_clear_bfqq_IO_bound(bfqq);
-+
-+	if (bfqd->low_latency && bfqq->wr_coeff == 1)
-+		bfqq->last_wr_start_finish = jiffies;
-+
-+	if (bfqd->low_latency && bfqd->bfq_wr_max_softrt_rate > 0 &&
-+	    RB_EMPTY_ROOT(&bfqq->sort_list)) {
-+		/*
-+		 * If we get here, and there are no outstanding
-+		 * requests, then the request pattern is isochronous
-+		 * (see the comments on the function
-+		 * bfq_bfqq_softrt_next_start()). Thus we can compute
-+		 * soft_rt_next_start. And we do it, unless bfqq is in
-+		 * interactive weight raising. We do not do it in the
-+		 * latter subcase, for the following reason. bfqq may
-+		 * be conveying the I/O needed to load a soft
-+		 * real-time application. Such an application will
-+		 * actually exhibit a soft real-time I/O pattern after
-+		 * it finally starts doing its job. But, if
-+		 * soft_rt_next_start is computed here for an
-+		 * interactive bfqq, and bfqq had received a lot of
-+		 * service before remaining with no outstanding
-+		 * request (likely to happen on a fast device), then
-+		 * soft_rt_next_start would be assigned such a high
-+		 * value that, for a very long time, bfqq would be
-+		 * prevented from being possibly considered as soft
-+		 * real time.
-+		 *
-+		 * If, instead, the queue still has outstanding
-+		 * requests, then we have to wait for the completion
-+		 * of all the outstanding requests to discover whether
-+		 * the request pattern is actually isochronous.
-+		 */
-+		BUG_ON(bfq_tot_busy_queues(bfqd) < 1);
-+		if (bfqq->dispatched == 0 &&
-+		    bfqq->wr_coeff != bfqd->bfq_wr_coeff) {
-+			bfqq->soft_rt_next_start =
-+				bfq_bfqq_softrt_next_start(bfqd, bfqq);
-+			bfq_log_bfqq(bfqd, bfqq, "new soft_rt_next %lu",
-+				     bfqq->soft_rt_next_start);
-+		} else if (bfqq->dispatched > 0) {
-+			/*
-+			 * Schedule an update of soft_rt_next_start to when
-+			 * the task may be discovered to be isochronous.
-+			 */
-+			bfq_mark_bfqq_softrt_update(bfqq);
-+		}
-+	}
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+	"expire (%s, slow %d, num_disp %d, short %d, weight %d, serv %d/%d)",
-+		     reason_name[reason], slow, bfqq->dispatched,
-+		     bfq_bfqq_has_short_ttime(bfqq), entity->weight,
-+		     entity->service, entity->budget);
-+
-+	/*
-+	 * Increase, decrease or leave budget unchanged according to
-+	 * reason.
-+	 */
-+	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
-+	__bfq_bfqq_recalc_budget(bfqd, bfqq, reason);
-+	BUG_ON(bfqq->next_rq == NULL &&
-+	       bfqq->entity.budget < bfqq->entity.service);
-+	ref = bfqq->ref;
-+	__bfq_bfqq_expire(bfqd, bfqq);
-+
-+	if (ref == 1) /* bfqq is gone, no more actions on it */
-+		return;
-+
-+	BUG_ON(ref > 1 &&
-+	       !bfq_bfqq_busy(bfqq) && reason == BFQ_BFQQ_BUDGET_EXHAUSTED &&
-+		!bfq_class_idle(bfqq));
-+
-+	bfqq->injected_service = 0;
-+
-+	/* mark bfqq as waiting a request only if a bic still points to it */
-+	if (!bfq_bfqq_busy(bfqq) &&
-+	    reason != BFQ_BFQQ_BUDGET_TIMEOUT &&
-+	    reason != BFQ_BFQQ_BUDGET_EXHAUSTED) {
-+		BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list));
-+		BUG_ON(bfqq->next_rq);
-+		bfq_mark_bfqq_non_blocking_wait_rq(bfqq);
-+		/*
-+		 * Not setting service to 0, because, if the next rq
-+		 * arrives in time, the queue will go on receiving
-+		 * service with this same budget (as if it never expired)
-+		 */
-+	} else {
-+		entity->service = 0;
-+		bfq_log_bfqq(bfqd, bfqq, "resetting service");
-+	}
-+
-+	/*
-+	 * Reset the received-service counter for every parent entity.
-+	 * Differently from what happens with bfqq->entity.service,
-+	 * the resetting of this counter never needs to be postponed
-+	 * for parent entities. In fact, in case bfqq may have a
-+	 * chance to go on being served using the last, partially
-+	 * consumed budget, bfqq->entity.service needs to be kept,
-+	 * because if bfqq then actually goes on being served using
-+	 * the same budget, the last value of bfqq->entity.service is
-+	 * needed to properly decrement bfqq->entity.budget by the
-+	 * portion already consumed. In contrast, it is not necessary
-+	 * to keep entity->service for parent entities too, because
-+	 * the bubble up of the new value of bfqq->entity.budget will
-+	 * make sure that the budgets of parent entities are correct,
-+	 * even in case bfqq and thus parent entities go on receiving
-+	 * service with the same budget.
-+	 */
-+	entity = entity->parent;
-+	for_each_entity(entity)
-+		entity->service = 0;
-+}
-+
-+/*
-+ * Budget timeout is not implemented through a dedicated timer, but
-+ * just checked on request arrivals and completions, as well as on
-+ * idle timer expirations.
-+ */
-+static bool bfq_bfqq_budget_timeout(struct bfq_queue *bfqq)
-+{
-+	return time_is_before_eq_jiffies(bfqq->budget_timeout);
-+}
-+
-+/*
-+ * If we expire a queue that is actively waiting (i.e., with the
-+ * device idled) for the arrival of a new request, then we may incur
-+ * the timestamp misalignment problem described in the body of the
-+ * function __bfq_activate_entity. Hence we return true only if this
-+ * condition does not hold, or if the queue is slow enough to deserve
-+ * only to be kicked off for preserving a high throughput.
-+ */
-+static bool bfq_may_expire_for_budg_timeout(struct bfq_queue *bfqq)
-+{
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		"wait_request %d left %d timeout %d",
-+		bfq_bfqq_wait_request(bfqq),
-+			bfq_bfqq_budget_left(bfqq) >=  bfqq->entity.budget / 3,
-+		bfq_bfqq_budget_timeout(bfqq));
-+
-+	return (!bfq_bfqq_wait_request(bfqq) ||
-+		bfq_bfqq_budget_left(bfqq) >=  bfqq->entity.budget / 3)
-+		&&
-+		bfq_bfqq_budget_timeout(bfqq);
-+}
-+
-+static bool idling_boosts_thr_without_issues(struct bfq_data *bfqd,
-+					     struct bfq_queue *bfqq)
-+{
-+	bool rot_without_queueing =
-+		!blk_queue_nonrot(bfqd->queue) && !bfqd->hw_tag,
-+		bfqq_sequential_and_IO_bound,
-+		idling_boosts_thr;
-+
-+	bfqq_sequential_and_IO_bound = !BFQQ_SEEKY(bfqq) &&
-+		bfq_bfqq_IO_bound(bfqq) && bfq_bfqq_has_short_ttime(bfqq);
-+	/*
-+	 * The next variable takes into account the cases where idling
-+	 * boosts the throughput.
-+	 *
-+	 * The value of the variable is computed considering, first, that
-+	 * idling is virtually always beneficial for the throughput if:
-+	 * (a) the device is not NCQ-capable and rotational, or
-+	 * (b) regardless of the presence of NCQ, the device is rotational and
-+	 *     the request pattern for bfqq is I/O-bound and sequential, or
-+	 * (c) regardless of whether it is rotational, the device is
-+	 *     not NCQ-capable and the request pattern for bfqq is
-+	 *     I/O-bound and sequential.
-+	 *
-+	 * Secondly, and in contrast to the above item (b), idling an
-+	 * NCQ-capable flash-based device would not boost the
-+	 * throughput even with sequential I/O; rather it would lower
-+	 * the throughput in proportion to how fast the device
-+	 * is. Accordingly, the next variable is true if any of the
-+	 * above conditions (a), (b) or (c) is true, and, in
-+	 * particular, happens to be false if bfqd is an NCQ-capable
-+	 * flash-based device.
-+	 */
-+	idling_boosts_thr = rot_without_queueing ||
-+		((!blk_queue_nonrot(bfqd->queue) || !bfqd->hw_tag) &&
-+		 bfqq_sequential_and_IO_bound);
-+
-+	bfq_log_bfqq(bfqd, bfqq, "idling_boosts_thr %d", idling_boosts_thr);
-+
-+	/*
-+	 * The return value of this function is equal to that of
-+	 * idling_boosts_thr, unless a special case holds. In this
-+	 * special case, described below, idling may cause problems to
-+	 * weight-raised queues.
-+	 *
-+	 * When the request pool is saturated (e.g., in the presence
-+	 * of write hogs), if the processes associated with
-+	 * non-weight-raised queues ask for requests at a lower rate,
-+	 * then processes associated with weight-raised queues have a
-+	 * higher probability to get a request from the pool
-+	 * immediately (or at least soon) when they need one. Thus
-+	 * they have a higher probability to actually get a fraction
-+	 * of the device throughput proportional to their high
-+	 * weight. This is especially true with NCQ-capable drives,
-+	 * which enqueue several requests in advance, and further
-+	 * reorder internally-queued requests.
-+	 *
-+	 * For this reason, we force to false the return value if
-+	 * there are weight-raised busy queues. In this case, and if
-+	 * bfqq is not weight-raised, this guarantees that the device
-+	 * is not idled for bfqq (if, instead, bfqq is weight-raised,
-+	 * then idling will be guaranteed by another variable, see
-+	 * below). Combined with the timestamping rules of BFQ (see
-+	 * [1] for details), this behavior causes bfqq, and hence any
-+	 * sync non-weight-raised queue, to get a lower number of
-+	 * requests served, and thus to ask for a lower number of
-+	 * requests from the request pool, before the busy
-+	 * weight-raised queues get served again. This often mitigates
-+	 * starvation problems in the presence of heavy write
-+	 * workloads and NCQ, thereby guaranteeing a higher
-+	 * application and system responsiveness in these hostile
-+	 * scenarios.
-+	 */
-+	return idling_boosts_thr &&
-+		bfqd->wr_busy_queues == 0;
-+}
-+
-+/*
-+ * There is a case where idling must be performed not for
-+ * throughput concerns, but to preserve service guarantees.
-+ *
-+ * To introduce this case, we can note that allowing the drive
-+ * to enqueue more than one request at a time, and hence
-+ * delegating de facto final scheduling decisions to the
-+ * drive's internal scheduler, entails loss of control on the
-+ * actual request service order. In particular, the critical
-+ * situation is when requests from different processes happen
-+ * to be present, at the same time, in the internal queue(s)
-+ * of the drive. In such a situation, the drive, by deciding
-+ * the service order of the internally-queued requests, does
-+ * determine also the actual throughput distribution among
-+ * these processes. But the drive typically has no notion or
-+ * concern about per-process throughput distribution, and
-+ * makes its decisions only on a per-request basis. Therefore,
-+ * the service distribution enforced by the drive's internal
-+ * scheduler is likely to coincide with the desired
-+ * device-throughput distribution only in a completely
-+ * symmetric scenario where:
-+ * (i)  each of these processes must get the same throughput as
-+ *      the others;
-+ * (ii) the I/O of each process has the same properties, in
-+ *      terms of locality (sequential or random), direction
-+ *      (reads or writes), request sizes, greediness
-+ *      (from I/O-bound to sporadic), and so on.
-+ * In fact, in such a scenario, the drive tends to treat
-+ * the requests of each of these processes in about the same
-+ * way as the requests of the others, and thus to provide
-+ * each of these processes with about the same throughput
-+ * (which is exactly the desired throughput distribution). In
-+ * contrast, in any asymmetric scenario, device idling is
-+ * certainly needed to guarantee that bfqq receives its
-+ * assigned fraction of the device throughput (see [1] for
-+ * details).
-+ * The problem is that idling may significantly reduce
-+ * throughput with certain combinations of types of I/O and
-+ * devices. An important example is sync random I/O, on flash
-+ * storage with command queueing. So, unless bfqq falls in the
-+ * above cases where idling also boosts throughput, it would
-+ * be important to check conditions (i) and (ii) accurately,
-+ * so as to avoid idling when not strictly needed for service
-+ * guarantees.
-+ *
-+ * Unfortunately, it is extremely difficult to thoroughly
-+ * check condition (ii). And, in case there are active groups,
-+ * it becomes very difficult to check condition (i) too. In
-+ * fact, if there are active groups, then, for condition (i)
-+ * to become false, it is enough that an active group contains
-+ * more active processes or sub-groups than some other active
-+ * group. More precisely, for condition (i) to hold because of
-+ * such a group, it is not even necessary that the group is
-+ * (still) active: it is sufficient that, even if the group
-+ * has become inactive, some of its descendant processes still
-+ * have some request already dispatched but still waiting for
-+ * completion. In fact, requests have still to be guaranteed
-+ * their share of the throughput even after being
-+ * dispatched. In this respect, it is easy to show that, if a
-+ * group frequently becomes inactive while still having
-+ * in-flight requests, and if, when this happens, the group is
-+ * not considered in the calculation of whether the scenario
-+ * is asymmetric, then the group may fail to be guaranteed its
-+ * fair share of the throughput (basically because idling may
-+ * not be performed for the descendant processes of the group,
-+ * but it had to be).  We address this issue with the
-+ * following bi-modal behavior, implemented in the function
-+ * bfq_symmetric_scenario().
-+ *
-+ * If there are groups with requests waiting for completion
-+ * (as commented above, some of these groups may even be
-+ * already inactive), then the scenario is tagged as
-+ * asymmetric, conservatively, without checking any of the
-+ * conditions (i) and (ii). So the device is idled for bfqq.
-+ * This behavior matches also the fact that groups are created
-+ * exactly if controlling I/O is a primary concern (to
-+ * preserve bandwidth and latency guarantees).
-+ *
-+ * On the opposite end, if there are no groups with requests
-+ * waiting for completion, then only condition (i) is actually
-+ * controlled, i.e., provided that condition (i) holds, idling
-+ * is not performed, regardless of whether condition (ii)
-+ * holds. In other words, only if condition (i) does not hold,
-+ * then idling is allowed, and the device tends to be
-+ * prevented from queueing many requests, possibly of several
-+ * processes. Since there are no groups with requests waiting
-+ * for completion, then, to control condition (i) it is enough
-+ * to check just whether all the queues with requests waiting
-+ * for completion also have the same weight.
-+ *
-+ * Not checking condition (ii) evidently exposes bfqq to the
-+ * risk of getting less throughput than its fair share.
-+ * However, for queues with the same weight, a further
-+ * mechanism, preemption, mitigates or even eliminates this
-+ * problem. And it does so without consequences on overall
-+ * throughput. This mechanism and its benefits are explained
-+ * in the next three paragraphs.
-+ *
-+ * Even if a queue, say Q, is expired when it remains idle, Q
-+ * can still preempt the new in-service queue if the next
-+ * request of Q arrives soon (see the comments on
-+ * bfq_bfqq_update_budg_for_activation). If all queues and
-+ * groups have the same weight, this form of preemption,
-+ * combined with the hole-recovery heuristic described in the
-+ * comments on function bfq_bfqq_update_budg_for_activation,
-+ * are enough to preserve a correct bandwidth distribution in
-+ * the mid term, even without idling. In fact, even if not
-+ * idling allows the internal queues of the device to contain
-+ * many requests, and thus to reorder requests, we can rather
-+ * safely assume that the internal scheduler still preserves a
-+ * minimum of mid-term fairness.
-+ *
-+ * More precisely, this preemption-based, idleless approach
-+ * provides fairness in terms of IOPS, and not sectors per
-+ * second. This can be seen with a simple example. Suppose
-+ * that there are two queues with the same weight, but that
-+ * the first queue receives requests of 8 sectors, while the
-+ * second queue receives requests of 1024 sectors. In
-+ * addition, suppose that each of the two queues contains at
-+ * most one request at a time, which implies that each queue
-+ * always remains idle after it is served. Finally, after
-+ * remaining idle, each queue receives very quickly a new
-+ * request. It follows that the two queues are served
-+ * alternatively, preempting each other if needed. This
-+ * implies that, although both queues have the same weight,
-+ * the queue with large requests receives a service that is
-+ * 1024/8 times as high as the service received by the other
-+ * queue.
-+ *
-+ * The motivation for using preemption instead of idling (for
-+ * queues with the same weight) is that, by not idling,
-+ * service guarantees are preserved (completely or at least in
-+ * part) without minimally sacrificing throughput. And, if
-+ * there is no active group, then the primary expectation for
-+ * this device is probably a high throughput.
-+ *
-+ * We are now left only with explaining the additional
-+ * compound condition that is checked below for deciding
-+ * whether the scenario is asymmetric. To explain this
-+ * compound condition, we need to add that the function
-+ * bfq_symmetric_scenario checks the weights of only
-+ * non-weight-raised queues, for efficiency reasons (see
-+ * comments on bfq_weights_tree_add()). Then the fact that
-+ * bfqq is weight-raised is checked explicitly here. More
-+ * precisely, the compound condition below takes into account
-+ * also the fact that, even if bfqq is being weight-raised,
-+ * the scenario is still symmetric if all queues with requests
-+ * waiting for completion happen to be
-+ * weight-raised. Actually, we should be even more precise
-+ * here, and differentiate between interactive weight raising
-+ * and soft real-time weight raising.
-+ *
-+ * As a side note, it is worth considering that the above
-+ * device-idling countermeasures may however fail in the
-+ * following unlucky scenario: if idling is (correctly)
-+ * disabled in a time period during which all symmetry
-+ * sub-conditions hold, and hence the device is allowed to
-+ * enqueue many requests, but at some later point in time some
-+ * sub-condition stops to hold, then it may become impossible
-+ * to let requests be served in the desired order until all
-+ * the requests already queued in the device have been served.
-+ */
-+static bool idling_needed_for_service_guarantees(struct bfq_data *bfqd,
-+						 struct bfq_queue *bfqq)
-+{
-+	bool asymmetric_scenario = (bfqq->wr_coeff > 1 &&
-+				    bfqd->wr_busy_queues <
-+				    bfq_tot_busy_queues(bfqd)) ||
-+		!bfq_symmetric_scenario(bfqd);
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+		     "wr_coeff %d wr_busy %d busy %d asymmetric %d",
-+		     bfqq->wr_coeff,
-+		     bfqd->wr_busy_queues,
-+		     bfq_tot_busy_queues(bfqd),
-+		     asymmetric_scenario);
-+
-+	return asymmetric_scenario;
-+}
-+
-+/*
-+ * For a queue that becomes empty, device idling is allowed only if
-+ * this function returns true for that queue. As a consequence, since
-+ * device idling plays a critical role for both throughput boosting
-+ * and service guarantees, the return value of this function plays a
-+ * critical role as well.
-+ *
-+ * In a nutshell, this function returns true only if idling is
-+ * beneficial for throughput or, even if detrimental for throughput,
-+ * idling is however necessary to preserve service guarantees (low
-+ * latency, desired throughput distribution, ...). In particular, on
-+ * NCQ-capable devices, this function tries to return false, so as to
-+ * help keep the drives' internal queues full, whenever this helps the
-+ * device boost the throughput without causing any service-guarantee
-+ * issue.
-+ *
-+ * Most of the issues taken into account to get the return value of
-+ * this function are not trivial. We discuss these issues in the two
-+ * functions providing the main pieces of information needed by this
-+ * function.
-+ */
-+static bool bfq_better_to_idle(struct bfq_queue *bfqq)
-+{
-+	struct bfq_data *bfqd = bfqq->bfqd;
-+	bool idling_boosts_thr_with_no_issue, idling_needed_for_service_guar;
-+
-+	if (unlikely(bfqd->strict_guarantees))
-+		return true;
-+
-+	/*
-+	 * Idling is performed only if slice_idle > 0. In addition, we
-+	 * do not idle if
-+	 * (a) bfqq is async
-+	 * (b) bfqq is in the idle io prio class: in this case we do
-+	 * not idle because we want to minimize the bandwidth that
-+	 * queues in this class can steal to higher-priority queues
-+	 */
-+	if (bfqd->bfq_slice_idle == 0 || !bfq_bfqq_sync(bfqq) ||
-+	   bfq_class_idle(bfqq))
-+		return false;
-+
-+	idling_boosts_thr_with_no_issue =
-+		idling_boosts_thr_without_issues(bfqd, bfqq);
-+
-+	idling_needed_for_service_guar =
-+		idling_needed_for_service_guarantees(bfqd, bfqq);
-+
-+	/*
-+	 * We have now the two components we need to compute the
-+	 * return value of the function, which is true only if idling
-+	 * either boosts the throughput (without issues), or is
-+	 * necessary to preserve service guarantees.
-+	 */
-+	bfq_log_bfqq(bfqd, bfqq,
-+		     "wr_busy %d boosts %d IO-bound %d guar %d",
-+		     bfqd->wr_busy_queues,
-+		     idling_boosts_thr_with_no_issue,
-+		     bfq_bfqq_IO_bound(bfqq),
-+		     idling_needed_for_service_guar);
-+
-+	return idling_boosts_thr_with_no_issue ||
-+		idling_needed_for_service_guar;
-+}
-+
-+/*
-+ * If the in-service queue is empty but the function bfq_better_to_idle
-+ * returns true, then:
-+ * 1) the queue must remain in service and cannot be expired, and
-+ * 2) the device must be idled to wait for the possible arrival of a new
-+ *    request for the queue.
-+ * See the comments on the function bfq_better_to_idle for the reasons
-+ * why performing device idling is the best choice to boost the throughput
-+ * and preserve service guarantees when bfq_better_to_idle itself
-+ * returns true.
-+ */
-+static bool bfq_bfqq_must_idle(struct bfq_queue *bfqq)
-+{
-+	return RB_EMPTY_ROOT(&bfqq->sort_list) && bfq_better_to_idle(bfqq);
-+}
-+
-+static struct bfq_queue *bfq_choose_bfqq_for_injection(struct bfq_data *bfqd)
-+{
-+	struct bfq_queue *bfqq;
-+
-+	/*
-+	 * A linear search; but, with a high probability, very few
-+	 * steps are needed to find a candidate queue, i.e., a queue
-+	 * with enough budget left for its next request. In fact:
-+	 * - BFQ dynamically updates the budget of every queue so as
-+	 *   to accomodate the expected backlog of the queue;
-+	 * - if a queue gets all its requests dispatched as injected
-+	 *   service, then the queue is removed from the active list
-+	 *   (and re-added only if it gets new requests, but with
-+	 *   enough budget for its new backlog).
-+	 */
-+	list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list)
-+		if (!RB_EMPTY_ROOT(&bfqq->sort_list) &&
-+		    bfq_serv_to_charge(bfqq->next_rq, bfqq) <=
-+		    bfq_bfqq_budget_left(bfqq)) {
-+			bfq_log_bfqq(bfqd, bfqq, "returned this queue");
-+			return bfqq;
-+		}
-+
-+	bfq_log(bfqd, "no queue found");
-+	return NULL;
-+}
-+
-+/*
-+ * Select a queue for service.  If we have a current queue in service,
-+ * check whether to continue servicing it, or retrieve and set a new one.
-+ */
-+static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd)
-+{
-+	struct bfq_queue *bfqq;
-+	struct request *next_rq;
-+	enum bfqq_expiration reason = BFQ_BFQQ_BUDGET_TIMEOUT;
-+
-+	bfqq = bfqd->in_service_queue;
-+	if (!bfqq)
-+		goto new_queue;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "already in-service queue");
-+
-+	/*
-+	 * Do not expire bfqq for budget timeout if bfqq may be about
-+	 * to enjoy device idling. The reason why, in this case, we
-+	 * prevent bfqq from expiring is the same as in the comments
-+	 * on the case where bfq_bfqq_must_idle() returns true, in
-+	 * bfq_completed_request().
-+	 */
-+	if (bfq_may_expire_for_budg_timeout(bfqq) &&
-+	    !bfq_bfqq_must_idle(bfqq))
-+		goto expire;
-+
-+check_queue:
-+	/*
-+	 * This loop is rarely executed more than once. Even when it
-+	 * happens, it is much more convenient to re-execute this loop
-+	 * than to return NULL and trigger a new dispatch to get a
-+	 * request served.
-+	 */
-+	next_rq = bfqq->next_rq;
-+	/*
-+	 * If bfqq has requests queued and it has enough budget left to
-+	 * serve them, keep the queue, otherwise expire it.
-+	 */
-+	if (next_rq) {
-+		BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list));
-+
-+		if (bfq_serv_to_charge(next_rq, bfqq) >
-+			bfq_bfqq_budget_left(bfqq)) {
-+			/*
-+			 * Expire the queue for budget exhaustion,
-+			 * which makes sure that the next budget is
-+			 * enough to serve the next request, even if
-+			 * it comes from the fifo expired path.
-+			 */
-+			reason = BFQ_BFQQ_BUDGET_EXHAUSTED;
-+			goto expire;
-+		} else {
-+			/*
-+			 * The idle timer may be pending because we may
-+			 * not disable disk idling even when a new request
-+			 * arrives.
-+			 */
-+			if (bfq_bfqq_wait_request(bfqq)) {
-+				BUG_ON(!hrtimer_active(&bfqd->idle_slice_timer));
-+				/*
-+				 * If we get here: 1) at least a new request
-+				 * has arrived but we have not disabled the
-+				 * timer because the request was too small,
-+				 * 2) then the block layer has unplugged
-+				 * the device, causing the dispatch to be
-+				 * invoked.
-+				 *
-+				 * Since the device is unplugged, now the
-+				 * requests are probably large enough to
-+				 * provide a reasonable throughput.
-+				 * So we disable idling.
-+				 */
-+				bfq_clear_bfqq_wait_request(bfqq);
-+				hrtimer_try_to_cancel(&bfqd->idle_slice_timer);
-+				bfqg_stats_update_idle_time(bfqq_group(bfqq));
-+			}
-+			goto keep_queue;
-+		}
-+	}
-+
-+	/*
-+	 * No requests pending. However, if the in-service queue is idling
-+	 * for a new request, or has requests waiting for a completion and
-+	 * may idle after their completion, then keep it anyway.
-+	 *
-+	 * Yet, to boost throughput, inject service from other queues if
-+	 * possible.
-+	 */
-+	if (hrtimer_active(&bfqd->idle_slice_timer) ||
-+	    (bfqq->dispatched != 0 && bfq_better_to_idle(bfqq))) {
-+		if (bfq_bfqq_injectable(bfqq) &&
-+		    bfqq->injected_service * bfqq->inject_coeff <
-+		    bfqq->entity.service * 10) {
-+			bfq_log_bfqq(bfqd, bfqq, "looking for queue for injection");
-+			bfqq = bfq_choose_bfqq_for_injection(bfqd);
-+		} else {
-+			if (BFQQ_SEEKY(bfqq))
-+				bfq_log_bfqq(bfqd, bfqq,
-+					"injection saturated %d * %d >= %d * 10",
-+					bfqq->injected_service, bfqq->inject_coeff,
-+					bfqq->entity.service);
-+			bfqq = NULL;
-+		}
-+		goto keep_queue;
-+	}
-+
-+	reason = BFQ_BFQQ_NO_MORE_REQUESTS;
-+expire:
-+	bfq_bfqq_expire(bfqd, bfqq, false, reason);
-+new_queue:
-+	bfqq = bfq_set_in_service_queue(bfqd);
-+	if (bfqq) {
-+		bfq_log_bfqq(bfqd, bfqq, "checking new queue");
-+		goto check_queue;
-+	}
-+keep_queue:
-+	if (bfqq)
-+		bfq_log_bfqq(bfqd, bfqq, "returned this queue");
-+	else
-+		bfq_log(bfqd, "no queue returned");
-+
-+	return bfqq;
-+}
-+
-+static void bfq_update_wr_data(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+
-+	if (bfqq->wr_coeff > 1) { /* queue is being weight-raised */
-+		BUG_ON(bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time &&
-+		       time_is_after_jiffies(bfqq->last_wr_start_finish));
-+
-+		bfq_log_bfqq(bfqd, bfqq,
-+			"raising period dur %u/%u msec, old coeff %u, w %d(%d)",
-+			jiffies_to_msecs(jiffies - bfqq->last_wr_start_finish),
-+			jiffies_to_msecs(bfqq->wr_cur_max_time),
-+			bfqq->wr_coeff,
-+			bfqq->entity.weight, bfqq->entity.orig_weight);
-+
-+		BUG_ON(bfqq != bfqd->in_service_queue && entity->weight !=
-+		       entity->orig_weight * bfqq->wr_coeff);
-+		if (entity->prio_changed)
-+			bfq_log_bfqq(bfqd, bfqq, "WARN: pending prio change");
-+
-+		/*
-+		 * If the queue was activated in a burst, or too much
-+		 * time has elapsed from the beginning of this
-+		 * weight-raising period, then end weight raising.
-+		 */
-+		if (bfq_bfqq_in_large_burst(bfqq))
-+			bfq_bfqq_end_wr(bfqq);
-+		else if (time_is_before_jiffies(bfqq->last_wr_start_finish +
-+					   bfqq->wr_cur_max_time)) {
-+			if (bfqq->wr_cur_max_time != bfqd->bfq_wr_rt_max_time ||
-+			time_is_before_jiffies(bfqq->wr_start_at_switch_to_srt +
-+					bfq_wr_duration(bfqd)))
-+				bfq_bfqq_end_wr(bfqq);
-+			else {
-+				switch_back_to_interactive_wr(bfqq, bfqd);
-+				BUG_ON(time_is_after_jiffies(
-+					       bfqq->last_wr_start_finish));
-+				bfqq->entity.prio_changed = 1;
-+				bfq_log_bfqq(bfqd, bfqq,
-+					"back to interactive wr");
-+			}
-+		}
-+		if (bfqq->wr_coeff > 1 &&
-+		       bfqq->wr_cur_max_time != bfqd->bfq_wr_rt_max_time &&
-+		       bfqq->service_from_wr > max_service_from_wr) {
-+			       /* see comments on max_service_from_wr */
-+			       bfq_bfqq_end_wr(bfqq);
-+			       bfq_log_bfqq(bfqd, bfqq,
-+					       "too much service");
-+	       }
-+	}
-+	/*
-+	 * To improve latency (for this or other queues), immediately
-+	 * update weight both if it must be raised and if it must be
-+	 * lowered. Since, entity may be on some active tree here, and
-+	 * might have a pending change of its ioprio class, invoke
-+	 * next function with the last parameter unset (see the
-+	 * comments on the function).
-+	 */
-+	if ((entity->weight > entity->orig_weight) != (bfqq->wr_coeff > 1))
-+		__bfq_entity_update_weight_prio(bfq_entity_service_tree(entity),
-+						entity, false);
-+}
-+
-+/*
-+ * Dispatch one request from bfqq, moving it to the request queue
-+ * dispatch list.
-+ */
-+static int bfq_dispatch_request(struct bfq_data *bfqd,
-+				struct bfq_queue *bfqq)
-+{
-+	int dispatched = 0;
-+	struct request *rq = bfqq->next_rq;
-+	unsigned long service_to_charge;
-+
-+	BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list));
-+	BUG_ON(!rq);
-+	service_to_charge = bfq_serv_to_charge(rq, bfqq);
-+
-+	BUG_ON(service_to_charge > bfq_bfqq_budget_left(bfqq));
-+
-+	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
-+
-+	bfq_bfqq_served(bfqq, service_to_charge);
-+
-+	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
-+
-+	bfq_dispatch_insert(bfqd->queue, rq);
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+	     "dispatched %u sec req (%llu), budg left %d, new disp_nr %d",
-+			blk_rq_sectors(rq),
-+			(unsigned long long) blk_rq_pos(rq),
-+		     bfq_bfqq_budget_left(bfqq),
-+		     bfqq->dispatched);
-+
-+	dispatched++;
-+
-+	if (bfqq != bfqd->in_service_queue) {
-+		if (likely(bfqd->in_service_queue)) {
-+			bfqd->in_service_queue->injected_service +=
-+				bfq_serv_to_charge(rq, bfqq);
-+			bfq_log_bfqq(bfqd, bfqd->in_service_queue,
-+				     "injected_service increased to %d",
-+				     bfqd->in_service_queue->injected_service);
-+		}
-+		return dispatched;
-+	}
-+
-+	/*
-+	 * If weight raising has to terminate for bfqq, then next
-+	 * function causes an immediate update of bfqq's weight,
-+	 * without waiting for next activation. As a consequence, on
-+	 * expiration, bfqq will be timestamped as if has never been
-+	 * weight-raised during this service slot, even if it has
-+	 * received part or even most of the service as a
-+	 * weight-raised queue. This inflates bfqq's timestamps, which
-+	 * is beneficial, as bfqq is then more willing to leave the
-+	 * device immediately to possible other weight-raised queues.
-+	 */
-+	bfq_update_wr_data(bfqd, bfqq);
-+
-+	if (!bfqd->in_service_bic) {
-+		atomic_long_inc(&RQ_BIC(rq)->icq.ioc->refcount);
-+		bfqd->in_service_bic = RQ_BIC(rq);
-+		BUG_ON(!bfqd->in_service_bic);
-+	}
-+
-+	if (bfq_tot_busy_queues(bfqd) > 1 && bfq_class_idle(bfqq))
-+		goto expire;
-+
-+	return dispatched;
-+
-+expire:
-+	bfq_bfqq_expire(bfqd, bfqq, false, BFQ_BFQQ_BUDGET_EXHAUSTED);
-+	return dispatched;
-+}
-+
-+static int __bfq_forced_dispatch_bfqq(struct bfq_queue *bfqq)
-+{
-+	int dispatched = 0;
-+
-+	while (bfqq->next_rq) {
-+		bfq_dispatch_insert(bfqq->bfqd->queue, bfqq->next_rq);
-+		dispatched++;
-+	}
-+
-+	BUG_ON(!list_empty(&bfqq->fifo));
-+	return dispatched;
-+}
-+
-+/*
-+ * Drain our current requests.
-+ * Used for barriers and when switching io schedulers on-the-fly.
-+ */
-+static int bfq_forced_dispatch(struct bfq_data *bfqd)
-+{
-+	struct bfq_queue *bfqq, *n;
-+	struct bfq_service_tree *st;
-+	int dispatched = 0;
-+
-+	bfqq = bfqd->in_service_queue;
-+	if (bfqq)
-+		__bfq_bfqq_expire(bfqd, bfqq);
-+
-+	/*
-+	 * Loop through classes, and be careful to leave the scheduler
-+	 * in a consistent state, as feedback mechanisms and vtime
-+	 * updates cannot be disabled during the process.
-+	 */
-+	list_for_each_entry_safe(bfqq, n, &bfqd->active_list, bfqq_list) {
-+		st = bfq_entity_service_tree(&bfqq->entity);
-+
-+		dispatched += __bfq_forced_dispatch_bfqq(bfqq);
-+
-+		bfqq->max_budget = bfq_max_budget(bfqd);
-+		bfq_forget_idle(st);
-+	}
-+
-+	BUG_ON(bfq_tot_busy_queues(bfqd) != 0);
-+
-+	return dispatched;
-+}
-+
-+static int bfq_dispatch_requests(struct request_queue *q, int force)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	struct bfq_queue *bfqq;
-+
-+	bfq_log(bfqd, "%d busy queues", bfq_tot_busy_queues(bfqd));
-+
-+	if (bfq_tot_busy_queues(bfqd) == 0)
-+		return 0;
-+
-+	if (unlikely(force))
-+		return bfq_forced_dispatch(bfqd);
-+
-+	/*
-+	 * Force device to serve one request at a time if
-+	 * strict_guarantees is true. Forcing this service scheme is
-+	 * currently the ONLY way to guarantee that the request
-+	 * service order enforced by the scheduler is respected by a
-+	 * queueing device. Otherwise the device is free even to make
-+	 * some unlucky request wait for as long as the device
-+	 * wishes.
-+	 *
-+	 * Of course, serving one request at at time may cause loss of
-+	 * throughput.
-+	 */
-+	if (bfqd->strict_guarantees && bfqd->rq_in_driver > 0)
-+		return 0;
-+
-+	bfqq = bfq_select_queue(bfqd);
-+	if (!bfqq)
-+		return 0;
-+
-+	BUG_ON(bfqq == bfqd->in_service_queue &&
-+	       bfqq->entity.budget < bfqq->entity.service);
-+
-+	BUG_ON(bfqq == bfqd->in_service_queue &&
-+	       bfq_bfqq_wait_request(bfqq));
-+
-+	if (!bfq_dispatch_request(bfqd, bfqq))
-+		return 0;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "%s request",
-+			bfq_bfqq_sync(bfqq) ? "sync" : "async");
-+
-+	BUG_ON(bfqq->next_rq == NULL &&
-+	       bfqq->entity.budget < bfqq->entity.service);
-+	return 1;
-+}
-+
-+/*
-+ * Task holds one reference to the queue, dropped when task exits.  Each rq
-+ * in-flight on this queue also holds a reference, dropped when rq is freed.
-+ *
-+ * Queue lock must be held here. Recall not to use bfqq after calling
-+ * this function on it.
-+ */
-+static void bfq_put_queue(struct bfq_queue *bfqq)
-+{
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	struct bfq_group *bfqg = bfqq_group(bfqq);
-+#endif
-+
-+	BUG_ON(bfqq->ref <= 0);
-+
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "%p %d", bfqq, bfqq->ref);
-+	bfqq->ref--;
-+	if (bfqq->ref)
-+		return;
-+
-+	BUG_ON(rb_first(&bfqq->sort_list));
-+	BUG_ON(bfqq->allocated[READ] + bfqq->allocated[WRITE] != 0);
-+	BUG_ON(bfqq->entity.tree);
-+	BUG_ON(bfq_bfqq_busy(bfqq));
-+
-+	if (!hlist_unhashed(&bfqq->burst_list_node)) {
-+		hlist_del_init(&bfqq->burst_list_node);
-+		/*
-+		 * Decrement also burst size after the removal, if the
-+		 * process associated with bfqq is exiting, and thus
-+		 * does not contribute to the burst any longer. This
-+		 * decrement helps filter out false positives of large
-+		 * bursts, when some short-lived process (often due to
-+		 * the execution of commands by some service) happens
-+		 * to start and exit while a complex application is
-+		 * starting, and thus spawning several processes that
-+		 * do I/O (and that *must not* be treated as a large
-+		 * burst, see comments on bfq_handle_burst).
-+		 *
-+		 * In particular, the decrement is performed only if:
-+		 * 1) bfqq is not a merged queue, because, if it is,
-+		 * then this free of bfqq is not triggered by the exit
-+		 * of the process bfqq is associated with, but exactly
-+		 * by the fact that bfqq has just been merged.
-+		 * 2) burst_size is greater than 0, to handle
-+		 * unbalanced decrements. Unbalanced decrements may
-+		 * happen in te following case: bfqq is inserted into
-+		 * the current burst list--without incrementing
-+		 * bust_size--because of a split, but the current
-+		 * burst list is not the burst list bfqq belonged to
-+		 * (see comments on the case of a split in
-+		 * bfq_set_request).
-+		 */
-+		if (bfqq->bic && bfqq->bfqd->burst_size > 0)
-+			bfqq->bfqd->burst_size--;
-+	}
-+
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "%p freed", bfqq);
-+
-+	kmem_cache_free(bfq_pool, bfqq);
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	bfqg_put(bfqg);
-+#endif
-+}
-+
-+static void bfq_put_cooperator(struct bfq_queue *bfqq)
-+{
-+	struct bfq_queue *__bfqq, *next;
-+
-+	/*
-+	 * If this queue was scheduled to merge with another queue, be
-+	 * sure to drop the reference taken on that queue (and others in
-+	 * the merge chain). See bfq_setup_merge and bfq_merge_bfqqs.
-+	 */
-+	__bfqq = bfqq->new_bfqq;
-+	while (__bfqq) {
-+		if (__bfqq == bfqq)
-+			break;
-+		next = __bfqq->new_bfqq;
-+		bfq_put_queue(__bfqq);
-+		__bfqq = next;
-+	}
-+}
-+
-+static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	if (bfqq == bfqd->in_service_queue) {
-+		__bfq_bfqq_expire(bfqd, bfqq);
-+		bfq_schedule_dispatch(bfqd);
-+	}
-+
-+	bfq_log_bfqq(bfqd, bfqq, "%p, %d", bfqq, bfqq->ref);
-+
-+	bfq_put_cooperator(bfqq);
-+
-+	bfq_put_queue(bfqq); /* release process reference */
-+}
-+
-+static void bfq_init_icq(struct io_cq *icq)
-+{
-+	icq_to_bic(icq)->ttime.last_end_request = ktime_get_ns() - (1ULL<<32);
-+}
-+
-+static void bfq_exit_icq(struct io_cq *icq)
-+{
-+	struct bfq_io_cq *bic = icq_to_bic(icq);
-+	struct bfq_data *bfqd = bic_to_bfqd(bic);
-+
-+	if (bic_to_bfqq(bic, false)) {
-+		bfq_exit_bfqq(bfqd, bic_to_bfqq(bic, false));
-+		bic_set_bfqq(bic, NULL, false);
-+	}
-+
-+	if (bic_to_bfqq(bic, true)) {
-+		/*
-+		 * If the bic is using a shared queue, put the reference
-+		 * taken on the io_context when the bic started using a
-+		 * shared bfq_queue.
-+		 */
-+		if (bfq_bfqq_coop(bic_to_bfqq(bic, true)))
-+			put_io_context(icq->ioc);
-+		bfq_exit_bfqq(bfqd, bic_to_bfqq(bic, true));
-+		bic_set_bfqq(bic, NULL, true);
-+	}
-+}
-+
-+/*
-+ * Update the entity prio values; note that the new values will not
-+ * be used until the next (re)activation.
-+ */
-+static void bfq_set_next_ioprio_data(struct bfq_queue *bfqq,
-+				     struct bfq_io_cq *bic)
-+{
-+	struct task_struct *tsk = current;
-+	int ioprio_class;
-+
-+	ioprio_class = IOPRIO_PRIO_CLASS(bic->ioprio);
-+	switch (ioprio_class) {
-+	default:
-+		dev_err(bfqq->bfqd->queue->backing_dev_info->dev,
-+			"bfq: bad prio class %d\n", ioprio_class);
-+	case IOPRIO_CLASS_NONE:
-+		/*
-+		 * No prio set, inherit CPU scheduling settings.
-+		 */
-+		bfqq->new_ioprio = task_nice_ioprio(tsk);
-+		bfqq->new_ioprio_class = task_nice_ioclass(tsk);
-+		break;
-+	case IOPRIO_CLASS_RT:
-+		bfqq->new_ioprio = IOPRIO_PRIO_DATA(bic->ioprio);
-+		bfqq->new_ioprio_class = IOPRIO_CLASS_RT;
-+		break;
-+	case IOPRIO_CLASS_BE:
-+		bfqq->new_ioprio = IOPRIO_PRIO_DATA(bic->ioprio);
-+		bfqq->new_ioprio_class = IOPRIO_CLASS_BE;
-+		break;
-+	case IOPRIO_CLASS_IDLE:
-+		bfqq->new_ioprio_class = IOPRIO_CLASS_IDLE;
-+		bfqq->new_ioprio = 7;
-+		break;
-+	}
-+
-+	if (bfqq->new_ioprio >= IOPRIO_BE_NR) {
-+		pr_crit("bfq_set_next_ioprio_data: new_ioprio %d\n",
-+			bfqq->new_ioprio);
-+		BUG();
-+	}
-+
-+	bfqq->entity.new_weight = bfq_ioprio_to_weight(bfqq->new_ioprio);
-+	bfqq->entity.prio_changed = 1;
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		     "bic_class %d prio %d class %d",
-+		     ioprio_class, bfqq->new_ioprio, bfqq->new_ioprio_class);
-+}
-+
-+static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio)
-+{
-+	struct bfq_data *bfqd = bic_to_bfqd(bic);
-+	struct bfq_queue *bfqq;
-+	unsigned long uninitialized_var(flags);
-+	int ioprio = bic->icq.ioc->ioprio;
-+
-+	/*
-+	 * This condition may trigger on a newly created bic, be sure to
-+	 * drop the lock before returning.
-+	 */
-+	if (unlikely(!bfqd) || likely(bic->ioprio == ioprio))
-+		return;
-+
-+	bic->ioprio = ioprio;
-+
-+	bfqq = bic_to_bfqq(bic, false);
-+	if (bfqq) {
-+		/* release process reference on this queue */
-+		bfq_put_queue(bfqq);
-+		bfqq = bfq_get_queue(bfqd, bio, BLK_RW_ASYNC, bic);
-+		bic_set_bfqq(bic, bfqq, false);
-+		bfq_log_bfqq(bfqd, bfqq,
-+			     "bfqq %p %d",
-+			     bfqq, bfqq->ref);
-+	}
-+
-+	bfqq = bic_to_bfqq(bic, true);
-+	if (bfqq)
-+		bfq_set_next_ioprio_data(bfqq, bic);
-+}
-+
-+static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+			  struct bfq_io_cq *bic, pid_t pid, int is_sync)
-+{
-+	RB_CLEAR_NODE(&bfqq->entity.rb_node);
-+	INIT_LIST_HEAD(&bfqq->fifo);
-+	INIT_HLIST_NODE(&bfqq->burst_list_node);
-+	BUG_ON(!hlist_unhashed(&bfqq->burst_list_node));
-+
-+	bfqq->ref = 0;
-+	bfqq->bfqd = bfqd;
-+
-+	if (bic)
-+		bfq_set_next_ioprio_data(bfqq, bic);
-+
-+	if (is_sync) {
-+		/*
-+		 * No need to mark as has_short_ttime if in
-+		 * idle_class, because no device idling is performed
-+		 * for queues in idle class
-+		 */
-+		if (!bfq_class_idle(bfqq))
-+			/* tentatively mark as has_short_ttime */
-+			bfq_mark_bfqq_has_short_ttime(bfqq);
-+		bfq_mark_bfqq_sync(bfqq);
-+		bfq_mark_bfqq_just_created(bfqq);
-+		/*
-+		 * Aggressively inject a lot of service: up to 90%.
-+		 * This coefficient remains constant during bfqq life,
-+		 * but this behavior might be changed, after enough
-+		 * testing and tuning.
-+		 */
-+		bfqq->inject_coeff = 1;
-+	} else
-+		bfq_clear_bfqq_sync(bfqq);
-+	bfq_mark_bfqq_IO_bound(bfqq);
-+
-+	/* Tentative initial value to trade off between thr and lat */
-+	bfqq->max_budget = (2 * bfq_max_budget(bfqd)) / 3;
-+	bfqq->pid = pid;
-+
-+	bfqq->wr_coeff = 1;
-+	bfqq->last_wr_start_finish = jiffies;
-+	bfqq->wr_start_at_switch_to_srt = bfq_smallest_from_now();
-+	bfqq->budget_timeout = bfq_smallest_from_now();
-+	bfqq->split_time = bfq_smallest_from_now();
-+
-+	/*
-+	 * To not forget the possibly high bandwidth consumed by a
-+	 * process/queue in the recent past,
-+	 * bfq_bfqq_softrt_next_start() returns a value at least equal
-+	 * to the current value of bfqq->soft_rt_next_start (see
-+	 * comments on bfq_bfqq_softrt_next_start).  Set
-+	 * soft_rt_next_start to now, to mean that bfqq has consumed
-+	 * no bandwidth so far.
-+	 */
-+	bfqq->soft_rt_next_start = jiffies;
-+
-+	/* first request is almost certainly seeky */
-+	bfqq->seek_history = 1;
-+}
-+
-+static struct bfq_queue **bfq_async_queue_prio(struct bfq_data *bfqd,
-+					       struct bfq_group *bfqg,
-+					       int ioprio_class, int ioprio)
-+{
-+	switch (ioprio_class) {
-+	case IOPRIO_CLASS_RT:
-+		return &bfqg->async_bfqq[0][ioprio];
-+	case IOPRIO_CLASS_NONE:
-+		ioprio = IOPRIO_NORM;
-+		/* fall through */
-+	case IOPRIO_CLASS_BE:
-+		return &bfqg->async_bfqq[1][ioprio];
-+	case IOPRIO_CLASS_IDLE:
-+		return &bfqg->async_idle_bfqq;
-+	default:
-+		BUG();
-+	}
-+}
-+
-+static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd,
-+				       struct bio *bio, bool is_sync,
-+				       struct bfq_io_cq *bic)
-+{
-+	const int ioprio = IOPRIO_PRIO_DATA(bic->ioprio);
-+	const int ioprio_class = IOPRIO_PRIO_CLASS(bic->ioprio);
-+	struct bfq_queue **async_bfqq = NULL;
-+	struct bfq_queue *bfqq;
-+	struct bfq_group *bfqg;
-+
-+	rcu_read_lock();
-+
-+	bfqg = bfq_find_set_group(bfqd, bio_blkcg(bio));
-+	if (!bfqg) {
-+		bfqq = &bfqd->oom_bfqq;
-+		goto out;
-+	}
-+
-+	if (!is_sync) {
-+		async_bfqq = bfq_async_queue_prio(bfqd, bfqg, ioprio_class,
-+						  ioprio);
-+		bfqq = *async_bfqq;
-+		if (bfqq)
-+			goto out;
-+	}
-+
-+	bfqq = kmem_cache_alloc_node(bfq_pool,
-+				     GFP_NOWAIT | __GFP_ZERO | __GFP_NOWARN,
-+				     bfqd->queue->node);
-+
-+	if (bfqq) {
-+		bfq_init_bfqq(bfqd, bfqq, bic, current->pid,
-+			      is_sync);
-+		bfq_init_entity(&bfqq->entity, bfqg);
-+		bfq_log_bfqq(bfqd, bfqq, "allocated");
-+	} else {
-+		bfqq = &bfqd->oom_bfqq;
-+		bfq_log_bfqq(bfqd, bfqq, "using oom bfqq");
-+		goto out;
-+	}
-+
-+	/*
-+	 * Pin the queue now that it's allocated, scheduler exit will
-+	 * prune it.
-+	 */
-+	if (async_bfqq) {
-+		bfqq->ref++; /*
-+			      * Extra group reference, w.r.t. sync
-+			      * queue. This extra reference is removed
-+			      * only if bfqq->bfqg disappears, to
-+			      * guarantee that this queue is not freed
-+			      * until its group goes away.
-+			      */
-+		bfq_log_bfqq(bfqd, bfqq, "bfqq not in async: %p, %d",
-+			     bfqq, bfqq->ref);
-+		*async_bfqq = bfqq;
-+	}
-+
-+out:
-+	bfqq->ref++; /* get a process reference to this queue */
-+	bfq_log_bfqq(bfqd, bfqq, "at end: %p, %d", bfqq, bfqq->ref);
-+	rcu_read_unlock();
-+	return bfqq;
-+}
-+
-+static void bfq_update_io_thinktime(struct bfq_data *bfqd,
-+				    struct bfq_io_cq *bic)
-+{
-+	struct bfq_ttime *ttime = &bic->ttime;
-+	u64 elapsed = ktime_get_ns() - bic->ttime.last_end_request;
-+
-+	elapsed = min_t(u64, elapsed, 2 * bfqd->bfq_slice_idle);
-+
-+	ttime->ttime_samples = (7*bic->ttime.ttime_samples + 256) / 8;
-+	ttime->ttime_total = div_u64(7*ttime->ttime_total + 256*elapsed,  8);
-+	ttime->ttime_mean = div64_ul(ttime->ttime_total + 128,
-+				     ttime->ttime_samples);
-+}
-+
-+static void
-+bfq_update_io_seektime(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+		       struct request *rq)
-+{
-+	bfqq->seek_history <<= 1;
-+	bfqq->seek_history |= BFQ_RQ_SEEKY(bfqd, bfqq->last_request_pos, rq);
-+}
-+
-+static void bfq_update_has_short_ttime(struct bfq_data *bfqd,
-+				       struct bfq_queue *bfqq,
-+				       struct bfq_io_cq *bic)
-+{
-+	bool has_short_ttime = true;
-+
-+	/*
-+	 * No need to update has_short_ttime if bfqq is async or in
-+	 * idle io prio class, or if bfq_slice_idle is zero, because
-+	 * no device idling is performed for bfqq in this case.
-+	 */
-+	if (!bfq_bfqq_sync(bfqq) || bfq_class_idle(bfqq) ||
-+	    bfqd->bfq_slice_idle == 0)
-+		return;
-+
-+	/* Idle window just restored, statistics are meaningless. */
-+	if (time_is_after_eq_jiffies(bfqq->split_time +
-+				     bfqd->bfq_wr_min_idle_time))
-+		return;
-+
-+	/* Think time is infinite if no process is linked to
-+	 * bfqq. Otherwise check average think time to
-+	 * decide whether to mark as has_short_ttime
-+	 */
-+	if (atomic_read(&bic->icq.ioc->active_ref) == 0 ||
-+	    (bfq_sample_valid(bic->ttime.ttime_samples) &&
-+	     bic->ttime.ttime_mean > bfqd->bfq_slice_idle))
-+		has_short_ttime = false;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "has_short_ttime %d",
-+		has_short_ttime);
-+
-+	if (has_short_ttime)
-+		bfq_mark_bfqq_has_short_ttime(bfqq);
-+	else
-+		bfq_clear_bfqq_has_short_ttime(bfqq);
-+}
-+
-+/*
-+ * Called when a new fs request (rq) is added to bfqq.  Check if there's
-+ * something we should do about it.
-+ */
-+static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+			    struct request *rq)
-+{
-+	struct bfq_io_cq *bic = RQ_BIC(rq);
-+
-+	if (rq->cmd_flags & REQ_META)
-+		bfqq->meta_pending++;
-+
-+	bfq_update_io_thinktime(bfqd, bic);
-+	bfq_update_has_short_ttime(bfqd, bfqq, bic);
-+	bfq_update_io_seektime(bfqd, bfqq, rq);
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+		     "has_short_ttime=%d (seeky %d)",
-+		     bfq_bfqq_has_short_ttime(bfqq), BFQQ_SEEKY(bfqq));
-+
-+	bfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
-+
-+	if (bfqq == bfqd->in_service_queue && bfq_bfqq_wait_request(bfqq)) {
-+		bool small_req = bfqq->queued[rq_is_sync(rq)] == 1 &&
-+				 blk_rq_sectors(rq) < 32;
-+		bool budget_timeout = bfq_bfqq_budget_timeout(bfqq);
-+
-+		/*
-+		 * There is just this request queued: if
-+		 * - the request is small, and
-+		 * - we are idling to boost throughput, and
-+		 * - the queue is not to be expired,
-+		 * then just exit.
-+		 *
-+		 * In this way, if the device is being idled to wait
-+		 * for a new request from the in-service queue, we
-+		 * avoid unplugging the device and committing the
-+		 * device to serve just a small request. In contrast
-+		 * we wait for the block layer to decide when to
-+		 * unplug the device: hopefully, new requests will be
-+		 * merged to this one quickly, then the device will be
-+		 * unplugged and larger requests will be dispatched.
-+		 */
-+		if (small_req && idling_boosts_thr_without_issues(bfqd, bfqq) &&
-+		    !budget_timeout)
-+			return;
-+
-+		/*
-+		 * A large enough request arrived, or idling is being
-+		 * performed to preserve service guarantees, or
-+		 * finally the queue is to be expired: in all these
-+		 * cases disk idling is to be stopped, so clear
-+		 * wait_request flag and reset timer.
-+		 */
-+		bfq_clear_bfqq_wait_request(bfqq);
-+		hrtimer_try_to_cancel(&bfqd->idle_slice_timer);
-+		bfqg_stats_update_idle_time(bfqq_group(bfqq));
-+
-+		/*
-+		 * The queue is not empty, because a new request just
-+		 * arrived. Hence we can safely expire the queue, in
-+		 * case of budget timeout, without risking that the
-+		 * timestamps of the queue are not updated correctly.
-+		 * See [1] for more details.
-+		 */
-+		if (budget_timeout)
-+			bfq_bfqq_expire(bfqd, bfqq, false,
-+					BFQ_BFQQ_BUDGET_TIMEOUT);
-+
-+		/*
-+		 * Let the request rip immediately, or let a new queue be
-+		 * selected if bfqq has just been expired.
-+		 */
-+		__blk_run_queue(bfqd->queue);
-+	}
-+}
-+
-+static void bfq_insert_request(struct request_queue *q, struct request *rq)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq), *new_bfqq;
-+
-+	assert_spin_locked(bfqd->queue->queue_lock);
-+
-+	/*
-+	 * An unplug may trigger a requeue of a request from the device
-+	 * driver: make sure we are in process context while trying to
-+	 * merge two bfq_queues.
-+	 */
-+	if (!in_interrupt()) {
-+		new_bfqq = bfq_setup_cooperator(bfqd, bfqq, rq, true);
-+		if (new_bfqq) {
-+			if (bic_to_bfqq(RQ_BIC(rq), 1) != bfqq)
-+				new_bfqq = bic_to_bfqq(RQ_BIC(rq), 1);
-+			/*
-+			 * Release the request's reference to the old bfqq
-+			 * and make sure one is taken to the shared queue.
-+			 */
-+			new_bfqq->allocated[rq_data_dir(rq)]++;
-+			bfqq->allocated[rq_data_dir(rq)]--;
-+			new_bfqq->ref++;
-+			if (bic_to_bfqq(RQ_BIC(rq), 1) == bfqq)
-+				bfq_merge_bfqqs(bfqd, RQ_BIC(rq),
-+						bfqq, new_bfqq);
-+
-+			bfq_clear_bfqq_just_created(bfqq);
-+			/*
-+			 * rq is about to be enqueued into new_bfqq,
-+			 * release rq reference on bfqq
-+			 */
-+			bfq_put_queue(bfqq);
-+			rq->elv.priv[1] = new_bfqq;
-+			bfqq = new_bfqq;
-+		}
-+	}
-+
-+	bfq_add_request(rq);
-+
-+	rq->fifo_time = ktime_get_ns() + bfqd->bfq_fifo_expire[rq_is_sync(rq)];
-+	list_add_tail(&rq->queuelist, &bfqq->fifo);
-+
-+	bfq_rq_enqueued(bfqd, bfqq, rq);
-+}
-+
-+static void bfq_update_hw_tag(struct bfq_data *bfqd)
-+{
-+	struct bfq_queue *bfqq = bfqd->in_service_queue;
-+
-+	bfqd->max_rq_in_driver = max_t(int, bfqd->max_rq_in_driver,
-+				       bfqd->rq_in_driver);
-+
-+	if (bfqd->hw_tag == 1)
-+		return;
-+
-+	/*
-+	 * This sample is valid if the number of outstanding requests
-+	 * is large enough to allow a queueing behavior.  Note that the
-+	 * sum is not exact, as it's not taking into account deactivated
-+	 * requests.
-+	 */
-+	if (bfqd->rq_in_driver + bfqd->queued <= BFQ_HW_QUEUE_THRESHOLD)
-+		return;
-+
-+	/*
-+	 * If active queue hasn't enough requests and can idle, bfq might not
-+	 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
-+	 * case
-+	 */
-+	if (bfqq && bfq_bfqq_has_short_ttime(bfqq) &&
-+	    bfqq->dispatched + bfqq->queued[0] + bfqq->queued[1] <
-+	    BFQ_HW_QUEUE_THRESHOLD && bfqd->rq_in_driver < BFQ_HW_QUEUE_THRESHOLD)
-+		return;
-+
-+	if (bfqd->hw_tag_samples++ < BFQ_HW_QUEUE_SAMPLES)
-+		return;
-+
-+	bfqd->hw_tag = bfqd->max_rq_in_driver > BFQ_HW_QUEUE_THRESHOLD;
-+	bfqd->max_rq_in_driver = 0;
-+	bfqd->hw_tag_samples = 0;
-+}
-+
-+static void bfq_completed_request(struct request_queue *q, struct request *rq)
-+{
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq);
-+	struct bfq_data *bfqd = bfqq->bfqd;
-+	u64 now_ns;
-+	u32 delta_us;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "completed one req with %u sects left",
-+		     blk_rq_sectors(rq));
-+
-+	assert_spin_locked(bfqd->queue->queue_lock);
-+	bfq_update_hw_tag(bfqd);
-+
-+	BUG_ON(!bfqd->rq_in_driver);
-+	BUG_ON(!bfqq->dispatched);
-+	bfqd->rq_in_driver--;
-+	bfqq->dispatched--;
-+	bfqg_stats_update_completion(bfqq_group(bfqq),
-+				     rq->start_time_ns,
-+				     rq->io_start_time_ns,
-+				     rq->cmd_flags);
-+
-+	if (!bfqq->dispatched && !bfq_bfqq_busy(bfqq)) {
-+		BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list));
-+		/*
-+		 * Set budget_timeout (which we overload to store the
-+		 * time at which the queue remains with no backlog and
-+		 * no outstanding request; used by the weight-raising
-+		 * mechanism).
-+		 */
-+		bfqq->budget_timeout = jiffies;
-+
-+		bfq_weights_tree_remove(bfqd, bfqq);
-+	}
-+
-+	now_ns = ktime_get_ns();
-+
-+	RQ_BIC(rq)->ttime.last_end_request = now_ns;
-+
-+	/*
-+	 * Using us instead of ns, to get a reasonable precision in
-+	 * computing rate in next check.
-+	 */
-+	delta_us = div_u64(now_ns - bfqd->last_completion, NSEC_PER_USEC);
-+
-+	bfq_log(bfqd, "delta %uus/%luus max_size %u rate %llu/%llu",
-+		delta_us, BFQ_MIN_TT/NSEC_PER_USEC, bfqd->last_rq_max_size,
-+		delta_us > 0 ?
-+		(USEC_PER_SEC*
-+		(u64)((bfqd->last_rq_max_size<<BFQ_RATE_SHIFT)/delta_us))
-+			>>BFQ_RATE_SHIFT :
-+		(USEC_PER_SEC*
-+		(u64)(bfqd->last_rq_max_size<<BFQ_RATE_SHIFT))>>BFQ_RATE_SHIFT,
-+		(USEC_PER_SEC*(u64)(1UL<<(BFQ_RATE_SHIFT-10)))>>BFQ_RATE_SHIFT);
-+
-+	/*
-+	 * If the request took rather long to complete, and, according
-+	 * to the maximum request size recorded, this completion latency
-+	 * implies that the request was certainly served at a very low
-+	 * rate (less than 1M sectors/sec), then the whole observation
-+	 * interval that lasts up to this time instant cannot be a
-+	 * valid time interval for computing a new peak rate.  Invoke
-+	 * bfq_update_rate_reset to have the following three steps
-+	 * taken:
-+	 * - close the observation interval at the last (previous)
-+	 *   request dispatch or completion
-+	 * - compute rate, if possible, for that observation interval
-+	 * - reset to zero samples, which will trigger a proper
-+	 *   re-initialization of the observation interval on next
-+	 *   dispatch
-+	 */
-+	if (delta_us > BFQ_MIN_TT/NSEC_PER_USEC &&
-+	   (bfqd->last_rq_max_size<<BFQ_RATE_SHIFT)/delta_us <
-+			1UL<<(BFQ_RATE_SHIFT - 10))
-+		bfq_update_rate_reset(bfqd, NULL);
-+	bfqd->last_completion = now_ns;
-+
-+	/*
-+	 * If we are waiting to discover whether the request pattern
-+	 * of the task associated with the queue is actually
-+	 * isochronous, and both requisites for this condition to hold
-+	 * are now satisfied, then compute soft_rt_next_start (see the
-+	 * comments on the function bfq_bfqq_softrt_next_start()). We
-+	 * do not compute soft_rt_next_start if bfqq is in interactive
-+	 * weight raising (see the comments in bfq_bfqq_expire() for
-+	 * an explanation). We schedule this delayed update when bfqq
-+	 * expires, if it still has in-flight requests.
-+	 */
-+	if (bfq_bfqq_softrt_update(bfqq) && bfqq->dispatched == 0 &&
-+	    RB_EMPTY_ROOT(&bfqq->sort_list) &&
-+	    bfqq->wr_coeff != bfqd->bfq_wr_coeff)
-+		bfqq->soft_rt_next_start =
-+			bfq_bfqq_softrt_next_start(bfqd, bfqq);
-+
-+	/*
-+	 * If this is the in-service queue, check if it needs to be expired,
-+	 * or if we want to idle in case it has no pending requests.
-+	 */
-+	if (bfqd->in_service_queue == bfqq) {
-+		if (bfq_bfqq_must_idle(bfqq)) {
-+			if (bfqq->dispatched == 0)
-+				bfq_arm_slice_timer(bfqd);
-+			/*
-+			 * If we get here, we do not expire bfqq, even
-+			 * if bfqq was in budget timeout or had no
-+			 * more requests (as controlled in the next
-+			 * conditional instructions). The reason for
-+			 * not expiring bfqq is as follows.
-+			 *
-+			 * Here bfqq->dispatched > 0 holds, but
-+			 * bfq_bfqq_must_idle() returned true. This
-+			 * implies that, even if no request arrives
-+			 * for bfqq before bfqq->dispatched reaches 0,
-+			 * bfqq will, however, not be expired on the
-+			 * completion event that causes bfqq->dispatch
-+			 * to reach zero. In contrast, on this event,
-+			 * bfqq will start enjoying device idling
-+			 * (I/O-dispatch plugging).
-+			 *
-+			 * But, if we expired bfqq here, bfqq would
-+			 * not have the chance to enjoy device idling
-+			 * when bfqq->dispatched finally reaches
-+			 * zero. This would expose bfqq to violation
-+			 * of its reserved service guarantees.
-+			 */
-+			goto out;
-+		} else if (bfq_may_expire_for_budg_timeout(bfqq))
-+			bfq_bfqq_expire(bfqd, bfqq, false,
-+					BFQ_BFQQ_BUDGET_TIMEOUT);
-+		else if (RB_EMPTY_ROOT(&bfqq->sort_list) &&
-+			 (bfqq->dispatched == 0 ||
-+			  !bfq_better_to_idle(bfqq)))
-+			bfq_bfqq_expire(bfqd, bfqq, false,
-+					BFQ_BFQQ_NO_MORE_REQUESTS);
-+	}
-+
-+	if (!bfqd->rq_in_driver)
-+		bfq_schedule_dispatch(bfqd);
-+
-+out:
-+	return;
-+}
-+
-+static int __bfq_may_queue(struct bfq_queue *bfqq)
-+{
-+	if (bfq_bfqq_wait_request(bfqq) && bfq_bfqq_must_alloc(bfqq)) {
-+		bfq_clear_bfqq_must_alloc(bfqq);
-+		return ELV_MQUEUE_MUST;
-+	}
-+
-+	return ELV_MQUEUE_MAY;
-+}
-+
-+static int bfq_may_queue(struct request_queue *q, unsigned int op)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	struct task_struct *tsk = current;
-+	struct bfq_io_cq *bic;
-+	struct bfq_queue *bfqq;
-+
-+	/*
-+	 * Don't force setup of a queue from here, as a call to may_queue
-+	 * does not necessarily imply that a request actually will be
-+	 * queued. So just lookup a possibly existing queue, or return
-+	 * 'may queue' if that fails.
-+	 */
-+	bic = bfq_bic_lookup(bfqd, tsk->io_context);
-+	if (!bic)
-+		return ELV_MQUEUE_MAY;
-+
-+	bfqq = bic_to_bfqq(bic, op_is_sync(op));
-+	if (bfqq)
-+		return __bfq_may_queue(bfqq);
-+
-+	return ELV_MQUEUE_MAY;
-+}
-+
-+/*
-+ * Queue lock held here.
-+ */
-+static void bfq_put_request(struct request *rq)
-+{
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq);
-+
-+	if (bfqq) {
-+		const int rw = rq_data_dir(rq);
-+
-+		BUG_ON(!bfqq->allocated[rw]);
-+		bfqq->allocated[rw]--;
-+
-+		rq->elv.priv[0] = NULL;
-+		rq->elv.priv[1] = NULL;
-+
-+		bfq_log_bfqq(bfqq->bfqd, bfqq, "%p, %d",
-+			     bfqq, bfqq->ref);
-+		bfq_put_queue(bfqq);
-+	}
-+}
-+
-+/*
-+ * Returns NULL if a new bfqq should be allocated, or the old bfqq if this
-+ * was the last process referring to that bfqq.
-+ */
-+static struct bfq_queue *
-+bfq_split_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq)
-+{
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "splitting queue");
-+
-+	put_io_context(bic->icq.ioc);
-+
-+	if (bfqq_process_refs(bfqq) == 1) {
-+		bfqq->pid = current->pid;
-+		bfq_clear_bfqq_coop(bfqq);
-+		bfq_clear_bfqq_split_coop(bfqq);
-+		return bfqq;
-+	}
-+
-+	bic_set_bfqq(bic, NULL, 1);
-+
-+	bfq_put_cooperator(bfqq);
-+
-+	bfq_put_queue(bfqq);
-+	return NULL;
-+}
-+
-+/*
-+ * Allocate bfq data structures associated with this request.
-+ */
-+static int bfq_set_request(struct request_queue *q, struct request *rq,
-+			   struct bio *bio, gfp_t gfp_mask)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	struct bfq_io_cq *bic = icq_to_bic(rq->elv.icq);
-+	const int rw = rq_data_dir(rq);
-+	const int is_sync = rq_is_sync(rq);
-+	struct bfq_queue *bfqq;
-+	unsigned long flags;
-+	bool bfqq_already_existing = false, split = false;
-+
-+	spin_lock_irqsave(q->queue_lock, flags);
-+
-+	if (!bic)
-+		goto queue_fail;
-+
-+	bfq_check_ioprio_change(bic, bio);
-+
-+	bfq_bic_update_cgroup(bic, bio);
-+
-+new_queue:
-+	bfqq = bic_to_bfqq(bic, is_sync);
-+	if (!bfqq || bfqq == &bfqd->oom_bfqq) {
-+		if (bfqq)
-+			bfq_put_queue(bfqq);
-+		bfqq = bfq_get_queue(bfqd, bio, is_sync, bic);
-+		BUG_ON(!hlist_unhashed(&bfqq->burst_list_node));
-+
-+		bic_set_bfqq(bic, bfqq, is_sync);
-+		if (split && is_sync) {
-+			bfq_log_bfqq(bfqd, bfqq,
-+				     "was_in_list %d "
-+				     "was_in_large_burst %d "
-+				     "large burst in progress %d",
-+				     bic->was_in_burst_list,
-+				     bic->saved_in_large_burst,
-+				     bfqd->large_burst);
-+
-+			if ((bic->was_in_burst_list && bfqd->large_burst) ||
-+			    bic->saved_in_large_burst) {
-+				bfq_log_bfqq(bfqd, bfqq,
-+					     "marking in "
-+					     "large burst");
-+				bfq_mark_bfqq_in_large_burst(bfqq);
-+			} else {
-+				bfq_log_bfqq(bfqd, bfqq,
-+					     "clearing in "
-+					     "large burst");
-+				bfq_clear_bfqq_in_large_burst(bfqq);
-+				if (bic->was_in_burst_list)
-+					/*
-+					 * If bfqq was in the current
-+					 * burst list before being
-+					 * merged, then we have to add
-+					 * it back. And we do not need
-+					 * to increase burst_size, as
-+					 * we did not decrement
-+					 * burst_size when we removed
-+					 * bfqq from the burst list as
-+					 * a consequence of a merge
-+					 * (see comments in
-+					 * bfq_put_queue). In this
-+					 * respect, it would be rather
-+					 * costly to know whether the
-+					 * current burst list is still
-+					 * the same burst list from
-+					 * which bfqq was removed on
-+					 * the merge. To avoid this
-+					 * cost, if bfqq was in a
-+					 * burst list, then we add
-+					 * bfqq to the current burst
-+					 * list without any further
-+					 * check. This can cause
-+					 * inappropriate insertions,
-+					 * but rarely enough to not
-+					 * harm the detection of large
-+					 * bursts significantly.
-+					 */
-+					hlist_add_head(&bfqq->burst_list_node,
-+						       &bfqd->burst_list);
-+			}
-+			bfqq->split_time = jiffies;
-+		}
-+	} else {
-+		/* If the queue was seeky for too long, break it apart. */
-+		if (bfq_bfqq_coop(bfqq) && bfq_bfqq_split_coop(bfqq)) {
-+			bfq_log_bfqq(bfqd, bfqq, "breaking apart bfqq");
-+
-+			/* Update bic before losing reference to bfqq */
-+			if (bfq_bfqq_in_large_burst(bfqq))
-+				bic->saved_in_large_burst = true;
-+
-+			bfqq = bfq_split_bfqq(bic, bfqq);
-+			split = true;
-+			if (!bfqq)
-+				goto new_queue;
-+			else
-+				bfqq_already_existing = true;
-+		}
-+	}
-+
-+	bfqq->allocated[rw]++;
-+	bfqq->ref++;
-+	bfq_log_bfqq(bfqd, bfqq, "bfqq %p, %d", bfqq, bfqq->ref);
-+
-+	rq->elv.priv[0] = bic;
-+	rq->elv.priv[1] = bfqq;
-+
-+	/*
-+	 * If a bfq_queue has only one process reference, it is owned
-+	 * by only one bfq_io_cq: we can set the bic field of the
-+	 * bfq_queue to the address of that structure. Also, if the
-+	 * queue has just been split, mark a flag so that the
-+	 * information is available to the other scheduler hooks.
-+	 */
-+	if (likely(bfqq != &bfqd->oom_bfqq) && bfqq_process_refs(bfqq) == 1) {
-+		bfqq->bic = bic;
-+		if (split) {
-+			/*
-+			 * If the queue has just been split from a shared
-+			 * queue, restore the idle window and the possible
-+			 * weight raising period.
-+			 */
-+			bfq_bfqq_resume_state(bfqq, bfqd, bic,
-+					      bfqq_already_existing);
-+		}
-+	}
-+
-+	if (unlikely(bfq_bfqq_just_created(bfqq)))
-+		bfq_handle_burst(bfqd, bfqq);
-+
-+	spin_unlock_irqrestore(q->queue_lock, flags);
-+
-+	return 0;
-+
-+queue_fail:
-+	bfq_schedule_dispatch(bfqd);
-+	spin_unlock_irqrestore(q->queue_lock, flags);
-+
-+	return 1;
-+}
-+
-+static void bfq_kick_queue(struct work_struct *work)
-+{
-+	struct bfq_data *bfqd =
-+		container_of(work, struct bfq_data, unplug_work);
-+	struct request_queue *q = bfqd->queue;
-+
-+	spin_lock_irq(q->queue_lock);
-+	__blk_run_queue(q);
-+	spin_unlock_irq(q->queue_lock);
-+}
-+
-+/*
-+ * Handler of the expiration of the timer running if the in-service queue
-+ * is idling inside its time slice.
-+ */
-+static enum hrtimer_restart bfq_idle_slice_timer(struct hrtimer *timer)
-+{
-+	struct bfq_data *bfqd = container_of(timer, struct bfq_data,
-+					     idle_slice_timer);
-+	struct bfq_queue *bfqq;
-+	unsigned long flags;
-+	enum bfqq_expiration reason;
-+
-+	spin_lock_irqsave(bfqd->queue->queue_lock, flags);
-+
-+	bfqq = bfqd->in_service_queue;
-+	/*
-+	 * Theoretical race here: the in-service queue can be NULL or
-+	 * different from the queue that was idling if the timer handler
-+	 * spins on the queue_lock and a new request arrives for the
-+	 * current queue and there is a full dispatch cycle that changes
-+	 * the in-service queue.  This can hardly happen, but in the worst
-+	 * case we just expire a queue too early.
-+	 */
-+	if (bfqq) {
-+		bfq_log_bfqq(bfqd, bfqq, "expired");
-+		bfq_clear_bfqq_wait_request(bfqq);
-+
-+		if (bfq_bfqq_budget_timeout(bfqq))
-+			/*
-+			 * Also here the queue can be safely expired
-+			 * for budget timeout without wasting
-+			 * guarantees
-+			 */
-+			reason = BFQ_BFQQ_BUDGET_TIMEOUT;
-+		else if (bfqq->queued[0] == 0 && bfqq->queued[1] == 0)
-+			/*
-+			 * The queue may not be empty upon timer expiration,
-+			 * because we may not disable the timer when the
-+			 * first request of the in-service queue arrives
-+			 * during disk idling.
-+			 */
-+			reason = BFQ_BFQQ_TOO_IDLE;
-+		else
-+			goto schedule_dispatch;
-+
-+		bfq_bfqq_expire(bfqd, bfqq, true, reason);
-+	}
-+
-+schedule_dispatch:
-+	bfq_schedule_dispatch(bfqd);
-+
-+	spin_unlock_irqrestore(bfqd->queue->queue_lock, flags);
-+	return HRTIMER_NORESTART;
-+}
-+
-+static void bfq_shutdown_timer_wq(struct bfq_data *bfqd)
-+{
-+	hrtimer_cancel(&bfqd->idle_slice_timer);
-+	cancel_work_sync(&bfqd->unplug_work);
-+}
-+
-+static void __bfq_put_async_bfqq(struct bfq_data *bfqd,
-+				 struct bfq_queue **bfqq_ptr)
-+{
-+	struct bfq_group *root_group = bfqd->root_group;
-+	struct bfq_queue *bfqq = *bfqq_ptr;
-+
-+	bfq_log(bfqd, "%p", bfqq);
-+	if (bfqq) {
-+		bfq_bfqq_move(bfqd, bfqq, root_group);
-+		bfq_log_bfqq(bfqd, bfqq, "putting %p, %d",
-+			     bfqq, bfqq->ref);
-+		bfq_put_queue(bfqq);
-+		*bfqq_ptr = NULL;
-+	}
-+}
-+
-+/*
-+ * Release all the bfqg references to its async queues.  If we are
-+ * deallocating the group these queues may still contain requests, so
-+ * we reparent them to the root cgroup (i.e., the only one that will
-+ * exist for sure until all the requests on a device are gone).
-+ */
-+static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg)
-+{
-+	int i, j;
-+
-+	for (i = 0; i < 2; i++)
-+		for (j = 0; j < IOPRIO_BE_NR; j++)
-+			__bfq_put_async_bfqq(bfqd, &bfqg->async_bfqq[i][j]);
-+
-+	__bfq_put_async_bfqq(bfqd, &bfqg->async_idle_bfqq);
-+}
-+
-+static void bfq_exit_queue(struct elevator_queue *e)
-+{
-+	struct bfq_data *bfqd = e->elevator_data;
-+	struct request_queue *q = bfqd->queue;
-+	struct bfq_queue *bfqq, *n;
-+
-+	bfq_shutdown_timer_wq(bfqd);
-+
-+	spin_lock_irq(q->queue_lock);
-+
-+	BUG_ON(bfqd->in_service_queue);
-+	list_for_each_entry_safe(bfqq, n, &bfqd->idle_list, bfqq_list)
-+		bfq_deactivate_bfqq(bfqd, bfqq, false, false);
-+
-+	spin_unlock_irq(q->queue_lock);
-+
-+	bfq_shutdown_timer_wq(bfqd);
-+
-+	BUG_ON(hrtimer_active(&bfqd->idle_slice_timer));
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	/* release oom-queue reference to root group */
-+	bfqg_put(bfqd->root_group);
-+
-+	blkcg_deactivate_policy(q, &blkcg_policy_bfq);
-+#else
-+	bfq_put_async_queues(bfqd, bfqd->root_group);
-+	kfree(bfqd->root_group);
-+#endif
-+
-+	kfree(bfqd);
-+}
-+
-+static void bfq_init_root_group(struct bfq_group *root_group,
-+				struct bfq_data *bfqd)
-+{
-+	int i;
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	root_group->entity.parent = NULL;
-+	root_group->my_entity = NULL;
-+	root_group->bfqd = bfqd;
-+#endif
-+	root_group->rq_pos_tree = RB_ROOT;
-+	for (i = 0; i < BFQ_IOPRIO_CLASSES; i++)
-+		root_group->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT;
-+	root_group->sched_data.bfq_class_idle_last_service = jiffies;
-+}
-+
-+static int bfq_init_queue(struct request_queue *q, struct elevator_type *e)
-+{
-+	struct bfq_data *bfqd;
-+	struct elevator_queue *eq;
-+
-+	eq = elevator_alloc(q, e);
-+	if (!eq)
-+		return -ENOMEM;
-+
-+	bfqd = kzalloc_node(sizeof(*bfqd), GFP_KERNEL, q->node);
-+	if (!bfqd) {
-+		kobject_put(&eq->kobj);
-+		return -ENOMEM;
-+	}
-+	eq->elevator_data = bfqd;
-+
-+	/*
-+	 * Our fallback bfqq if bfq_find_alloc_queue() runs into OOM issues.
-+	 * Grab a permanent reference to it, so that the normal code flow
-+	 * will not attempt to free it.
-+	 */
-+	bfq_init_bfqq(bfqd, &bfqd->oom_bfqq, NULL, 1, 0);
-+	bfqd->oom_bfqq.ref++;
-+	bfqd->oom_bfqq.new_ioprio = BFQ_DEFAULT_QUEUE_IOPRIO;
-+	bfqd->oom_bfqq.new_ioprio_class = IOPRIO_CLASS_BE;
-+	bfqd->oom_bfqq.entity.new_weight =
-+		bfq_ioprio_to_weight(bfqd->oom_bfqq.new_ioprio);
-+
-+	/* oom_bfqq does not participate to bursts */
-+	bfq_clear_bfqq_just_created(&bfqd->oom_bfqq);
-+	/*
-+	 * Trigger weight initialization, according to ioprio, at the
-+	 * oom_bfqq's first activation. The oom_bfqq's ioprio and ioprio
-+	 * class won't be changed any more.
-+	 */
-+	bfqd->oom_bfqq.entity.prio_changed = 1;
-+
-+	bfqd->queue = q;
-+
-+	spin_lock_irq(q->queue_lock);
-+	q->elevator = eq;
-+	spin_unlock_irq(q->queue_lock);
-+
-+	bfqd->root_group = bfq_create_group_hierarchy(bfqd, q->node);
-+	if (!bfqd->root_group)
-+		goto out_free;
-+	bfq_init_root_group(bfqd->root_group, bfqd);
-+	bfq_init_entity(&bfqd->oom_bfqq.entity, bfqd->root_group);
-+
-+	hrtimer_init(&bfqd->idle_slice_timer, CLOCK_MONOTONIC,
-+		     HRTIMER_MODE_REL);
-+	bfqd->idle_slice_timer.function = bfq_idle_slice_timer;
-+
-+	bfqd->queue_weights_tree = RB_ROOT;
-+	bfqd->num_groups_with_pending_reqs = 0;
-+
-+	INIT_WORK(&bfqd->unplug_work, bfq_kick_queue);
-+
-+	INIT_LIST_HEAD(&bfqd->active_list);
-+	INIT_LIST_HEAD(&bfqd->idle_list);
-+	INIT_HLIST_HEAD(&bfqd->burst_list);
-+
-+	bfqd->hw_tag = -1;
-+
-+	bfqd->bfq_max_budget = bfq_default_max_budget;
-+
-+	bfqd->bfq_fifo_expire[0] = bfq_fifo_expire[0];
-+	bfqd->bfq_fifo_expire[1] = bfq_fifo_expire[1];
-+	bfqd->bfq_back_max = bfq_back_max;
-+	bfqd->bfq_back_penalty = bfq_back_penalty;
-+	bfqd->bfq_slice_idle = bfq_slice_idle;
-+	bfqd->bfq_timeout = bfq_timeout;
-+
-+	bfqd->bfq_requests_within_timer = 120;
-+
-+	bfqd->bfq_large_burst_thresh = 8;
-+	bfqd->bfq_burst_interval = msecs_to_jiffies(180);
-+
-+	bfqd->low_latency = true;
-+
-+	/*
-+	 * Trade-off between responsiveness and fairness.
-+	 */
-+	bfqd->bfq_wr_coeff = 30;
-+	bfqd->bfq_wr_rt_max_time = msecs_to_jiffies(300);
-+	bfqd->bfq_wr_max_time = 0;
-+	bfqd->bfq_wr_min_idle_time = msecs_to_jiffies(2000);
-+	bfqd->bfq_wr_min_inter_arr_async = msecs_to_jiffies(500);
-+	bfqd->bfq_wr_max_softrt_rate = 7000; /*
-+					      * Approximate rate required
-+					      * to playback or record a
-+					      * high-definition compressed
-+					      * video.
-+					      */
-+	bfqd->wr_busy_queues = 0;
-+
-+	/*
-+	 * Begin by assuming, optimistically, that the device peak
-+	 * rate is equal to 2/3 of the highest reference rate.
-+	 */
-+	bfqd->rate_dur_prod = ref_rate[blk_queue_nonrot(bfqd->queue)] *
-+		ref_wr_duration[blk_queue_nonrot(bfqd->queue)];
-+	bfqd->peak_rate = ref_rate[blk_queue_nonrot(bfqd->queue)] * 2 / 3;
-+
-+	return 0;
-+
-+out_free:
-+	kfree(bfqd);
-+	kobject_put(&eq->kobj);
-+	return -ENOMEM;
-+}
-+
-+static void bfq_registered_queue(struct request_queue *q)
-+{
-+	wbt_disable_default(q);
-+}
-+
-+static void bfq_slab_kill(void)
-+{
-+	kmem_cache_destroy(bfq_pool);
-+}
-+
-+static int __init bfq_slab_setup(void)
-+{
-+	bfq_pool = KMEM_CACHE(bfq_queue, 0);
-+	if (!bfq_pool)
-+		return -ENOMEM;
-+	return 0;
-+}
-+
-+static ssize_t bfq_var_show(unsigned int var, char *page)
-+{
-+	return sprintf(page, "%u\n", var);
-+}
-+
-+static ssize_t bfq_var_store(unsigned long *var, const char *page,
-+			     size_t count)
-+{
-+	unsigned long new_val;
-+	int ret = kstrtoul(page, 10, &new_val);
-+
-+	if (ret == 0)
-+		*var = new_val;
-+
-+	return count;
-+}
-+
-+static ssize_t bfq_wr_max_time_show(struct elevator_queue *e, char *page)
-+{
-+	struct bfq_data *bfqd = e->elevator_data;
-+
-+	return sprintf(page, "%d\n", bfqd->bfq_wr_max_time > 0 ?
-+		       jiffies_to_msecs(bfqd->bfq_wr_max_time) :
-+		       jiffies_to_msecs(bfq_wr_duration(bfqd)));
-+}
-+
-+static ssize_t bfq_weights_show(struct elevator_queue *e, char *page)
-+{
-+	struct bfq_queue *bfqq;
-+	struct bfq_data *bfqd = e->elevator_data;
-+	ssize_t num_char = 0;
-+
-+	num_char += sprintf(page + num_char, "Tot reqs queued %d\n\n",
-+			    bfqd->queued);
-+
-+	spin_lock_irq(bfqd->queue->queue_lock);
-+
-+	num_char += sprintf(page + num_char, "Active:\n");
-+	list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list) {
-+		num_char += sprintf(page + num_char,
-+				    "pid%d: weight %hu, nr_queued %d %d, ",
-+				    bfqq->pid,
-+				    bfqq->entity.weight,
-+				    bfqq->queued[0],
-+				    bfqq->queued[1]);
-+		num_char += sprintf(page + num_char,
-+				    "dur %d/%u\n",
-+				    jiffies_to_msecs(
-+					    jiffies -
-+					    bfqq->last_wr_start_finish),
-+				    jiffies_to_msecs(bfqq->wr_cur_max_time));
-+	}
-+
-+	num_char += sprintf(page + num_char, "Idle:\n");
-+	list_for_each_entry(bfqq, &bfqd->idle_list, bfqq_list) {
-+		num_char += sprintf(page + num_char,
-+				    "pid%d: weight %hu, dur %d/%u\n",
-+				    bfqq->pid,
-+				    bfqq->entity.weight,
-+				    jiffies_to_msecs(jiffies -
-+						     bfqq->last_wr_start_finish),
-+				    jiffies_to_msecs(bfqq->wr_cur_max_time));
-+	}
-+
-+	spin_unlock_irq(bfqd->queue->queue_lock);
-+
-+	return num_char;
-+}
-+
-+#define SHOW_FUNCTION(__FUNC, __VAR, __CONV)				\
-+static ssize_t __FUNC(struct elevator_queue *e, char *page)		\
-+{									\
-+	struct bfq_data *bfqd = e->elevator_data;			\
-+	u64 __data = __VAR;						\
-+	if (__CONV == 1)						\
-+		__data = jiffies_to_msecs(__data);			\
-+	else if (__CONV == 2)						\
-+		__data = div_u64(__data, NSEC_PER_MSEC);		\
-+	return bfq_var_show(__data, (page));				\
-+}
-+SHOW_FUNCTION(bfq_fifo_expire_sync_show, bfqd->bfq_fifo_expire[1], 2);
-+SHOW_FUNCTION(bfq_fifo_expire_async_show, bfqd->bfq_fifo_expire[0], 2);
-+SHOW_FUNCTION(bfq_back_seek_max_show, bfqd->bfq_back_max, 0);
-+SHOW_FUNCTION(bfq_back_seek_penalty_show, bfqd->bfq_back_penalty, 0);
-+SHOW_FUNCTION(bfq_slice_idle_show, bfqd->bfq_slice_idle, 2);
-+SHOW_FUNCTION(bfq_max_budget_show, bfqd->bfq_user_max_budget, 0);
-+SHOW_FUNCTION(bfq_timeout_sync_show, bfqd->bfq_timeout, 1);
-+SHOW_FUNCTION(bfq_strict_guarantees_show, bfqd->strict_guarantees, 0);
-+SHOW_FUNCTION(bfq_low_latency_show, bfqd->low_latency, 0);
-+SHOW_FUNCTION(bfq_wr_coeff_show, bfqd->bfq_wr_coeff, 0);
-+SHOW_FUNCTION(bfq_wr_rt_max_time_show, bfqd->bfq_wr_rt_max_time, 1);
-+SHOW_FUNCTION(bfq_wr_min_idle_time_show, bfqd->bfq_wr_min_idle_time, 1);
-+SHOW_FUNCTION(bfq_wr_min_inter_arr_async_show, bfqd->bfq_wr_min_inter_arr_async,
-+	1);
-+SHOW_FUNCTION(bfq_wr_max_softrt_rate_show, bfqd->bfq_wr_max_softrt_rate, 0);
-+#undef SHOW_FUNCTION
-+
-+#define USEC_SHOW_FUNCTION(__FUNC, __VAR)				\
-+static ssize_t __FUNC(struct elevator_queue *e, char *page)		\
-+{									\
-+	struct bfq_data *bfqd = e->elevator_data;			\
-+	u64 __data = __VAR;						\
-+	__data = div_u64(__data, NSEC_PER_USEC);			\
-+	return bfq_var_show(__data, (page));				\
-+}
-+USEC_SHOW_FUNCTION(bfq_slice_idle_us_show, bfqd->bfq_slice_idle);
-+#undef USEC_SHOW_FUNCTION
-+
-+#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV)			\
-+static ssize_t								\
-+__FUNC(struct elevator_queue *e, const char *page, size_t count)	\
-+{									\
-+	struct bfq_data *bfqd = e->elevator_data;			\
-+	unsigned long uninitialized_var(__data);			\
-+	int ret = bfq_var_store(&__data, (page), count);		\
-+	if (__data < (MIN))						\
-+		__data = (MIN);						\
-+	else if (__data > (MAX))					\
-+		__data = (MAX);						\
-+	if (__CONV == 1)						\
-+		*(__PTR) = msecs_to_jiffies(__data);			\
-+	else if (__CONV == 2)						\
-+		*(__PTR) = (u64)__data * NSEC_PER_MSEC;			\
-+	else								\
-+		*(__PTR) = __data;					\
-+	return ret;							\
-+}
-+STORE_FUNCTION(bfq_fifo_expire_sync_store, &bfqd->bfq_fifo_expire[1], 1,
-+		INT_MAX, 2);
-+STORE_FUNCTION(bfq_fifo_expire_async_store, &bfqd->bfq_fifo_expire[0], 1,
-+		INT_MAX, 2);
-+STORE_FUNCTION(bfq_back_seek_max_store, &bfqd->bfq_back_max, 0, INT_MAX, 0);
-+STORE_FUNCTION(bfq_back_seek_penalty_store, &bfqd->bfq_back_penalty, 1,
-+		INT_MAX, 0);
-+STORE_FUNCTION(bfq_slice_idle_store, &bfqd->bfq_slice_idle, 0, INT_MAX, 2);
-+STORE_FUNCTION(bfq_wr_coeff_store, &bfqd->bfq_wr_coeff, 1, INT_MAX, 0);
-+STORE_FUNCTION(bfq_wr_max_time_store, &bfqd->bfq_wr_max_time, 0, INT_MAX, 1);
-+STORE_FUNCTION(bfq_wr_rt_max_time_store, &bfqd->bfq_wr_rt_max_time, 0, INT_MAX,
-+		1);
-+STORE_FUNCTION(bfq_wr_min_idle_time_store, &bfqd->bfq_wr_min_idle_time, 0,
-+		INT_MAX, 1);
-+STORE_FUNCTION(bfq_wr_min_inter_arr_async_store,
-+		&bfqd->bfq_wr_min_inter_arr_async, 0, INT_MAX, 1);
-+STORE_FUNCTION(bfq_wr_max_softrt_rate_store, &bfqd->bfq_wr_max_softrt_rate, 0,
-+		INT_MAX, 0);
-+#undef STORE_FUNCTION
-+
-+#define USEC_STORE_FUNCTION(__FUNC, __PTR, MIN, MAX)			\
-+static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count)\
-+{									\
-+	struct bfq_data *bfqd = e->elevator_data;			\
-+	unsigned long uninitialized_var(__data);			\
-+	int ret = bfq_var_store(&__data, (page), count);		\
-+	if (__data < (MIN))						\
-+		__data = (MIN);						\
-+	else if (__data > (MAX))					\
-+		__data = (MAX);						\
-+	*(__PTR) = (u64)__data * NSEC_PER_USEC;				\
-+	return ret;							\
-+}
-+USEC_STORE_FUNCTION(bfq_slice_idle_us_store, &bfqd->bfq_slice_idle, 0,
-+		    UINT_MAX);
-+#undef USEC_STORE_FUNCTION
-+
-+/* do nothing for the moment */
-+static ssize_t bfq_weights_store(struct elevator_queue *e,
-+				    const char *page, size_t count)
-+{
-+	return count;
-+}
-+
-+static ssize_t bfq_max_budget_store(struct elevator_queue *e,
-+				    const char *page, size_t count)
-+{
-+	struct bfq_data *bfqd = e->elevator_data;
-+	unsigned long uninitialized_var(__data);
-+	int ret = bfq_var_store(&__data, (page), count);
-+
-+	if (__data == 0)
-+		bfqd->bfq_max_budget = bfq_calc_max_budget(bfqd);
-+	else {
-+		if (__data > INT_MAX)
-+			__data = INT_MAX;
-+		bfqd->bfq_max_budget = __data;
-+	}
-+
-+	bfqd->bfq_user_max_budget = __data;
-+
-+	return ret;
-+}
-+
-+/*
-+ * Leaving this name to preserve name compatibility with cfq
-+ * parameters, but this timeout is used for both sync and async.
-+ */
-+static ssize_t bfq_timeout_sync_store(struct elevator_queue *e,
-+				      const char *page, size_t count)
-+{
-+	struct bfq_data *bfqd = e->elevator_data;
-+	unsigned long uninitialized_var(__data);
-+	int ret = bfq_var_store(&__data, (page), count);
-+
-+	if (__data < 1)
-+		__data = 1;
-+	else if (__data > INT_MAX)
-+		__data = INT_MAX;
-+
-+	bfqd->bfq_timeout = msecs_to_jiffies(__data);
-+	if (bfqd->bfq_user_max_budget == 0)
-+		bfqd->bfq_max_budget = bfq_calc_max_budget(bfqd);
-+
-+	return ret;
-+}
-+
-+static ssize_t bfq_strict_guarantees_store(struct elevator_queue *e,
-+				     const char *page, size_t count)
-+{
-+	struct bfq_data *bfqd = e->elevator_data;
-+	unsigned long uninitialized_var(__data);
-+	int ret = bfq_var_store(&__data, (page), count);
-+
-+	if (__data > 1)
-+		__data = 1;
-+	if (!bfqd->strict_guarantees && __data == 1
-+	    && bfqd->bfq_slice_idle < 8 * NSEC_PER_MSEC)
-+		bfqd->bfq_slice_idle = 8 * NSEC_PER_MSEC;
-+
-+	bfqd->strict_guarantees = __data;
-+
-+	return ret;
-+}
-+
-+static ssize_t bfq_low_latency_store(struct elevator_queue *e,
-+				     const char *page, size_t count)
-+{
-+	struct bfq_data *bfqd = e->elevator_data;
-+	unsigned long uninitialized_var(__data);
-+	int ret = bfq_var_store(&__data, (page), count);
-+
-+	if (__data > 1)
-+		__data = 1;
-+	if (__data == 0 && bfqd->low_latency != 0)
-+		bfq_end_wr(bfqd);
-+	bfqd->low_latency = __data;
-+
-+	return ret;
-+}
-+
-+#define BFQ_ATTR(name) \
-+	__ATTR(name, S_IRUGO|S_IWUSR, bfq_##name##_show, bfq_##name##_store)
-+
-+static struct elv_fs_entry bfq_attrs[] = {
-+	BFQ_ATTR(fifo_expire_sync),
-+	BFQ_ATTR(fifo_expire_async),
-+	BFQ_ATTR(back_seek_max),
-+	BFQ_ATTR(back_seek_penalty),
-+	BFQ_ATTR(slice_idle),
-+	BFQ_ATTR(slice_idle_us),
-+	BFQ_ATTR(max_budget),
-+	BFQ_ATTR(timeout_sync),
-+	BFQ_ATTR(strict_guarantees),
-+	BFQ_ATTR(low_latency),
-+	BFQ_ATTR(wr_coeff),
-+	BFQ_ATTR(wr_max_time),
-+	BFQ_ATTR(wr_rt_max_time),
-+	BFQ_ATTR(wr_min_idle_time),
-+	BFQ_ATTR(wr_min_inter_arr_async),
-+	BFQ_ATTR(wr_max_softrt_rate),
-+	BFQ_ATTR(weights),
-+	__ATTR_NULL
-+};
-+
-+static struct elevator_type iosched_bfq = {
-+	.ops.sq = {
-+		.elevator_merge_fn =		bfq_merge,
-+		.elevator_merged_fn =		bfq_merged_request,
-+		.elevator_merge_req_fn =	bfq_merged_requests,
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+		.elevator_bio_merged_fn =	bfq_bio_merged,
-+#endif
-+		.elevator_allow_bio_merge_fn =	bfq_allow_bio_merge,
-+		.elevator_allow_rq_merge_fn =	bfq_allow_rq_merge,
-+		.elevator_dispatch_fn =		bfq_dispatch_requests,
-+		.elevator_add_req_fn =		bfq_insert_request,
-+		.elevator_activate_req_fn =	bfq_activate_request,
-+		.elevator_deactivate_req_fn =	bfq_deactivate_request,
-+		.elevator_completed_req_fn =	bfq_completed_request,
-+		.elevator_former_req_fn =	elv_rb_former_request,
-+		.elevator_latter_req_fn =	elv_rb_latter_request,
-+		.elevator_init_icq_fn =		bfq_init_icq,
-+		.elevator_exit_icq_fn =		bfq_exit_icq,
-+		.elevator_set_req_fn =		bfq_set_request,
-+		.elevator_put_req_fn =		bfq_put_request,
-+		.elevator_may_queue_fn =	bfq_may_queue,
-+		.elevator_init_fn =		bfq_init_queue,
-+		.elevator_exit_fn =		bfq_exit_queue,
-+		.elevator_registered_fn =	bfq_registered_queue,
-+	},
-+	.icq_size =		sizeof(struct bfq_io_cq),
-+	.icq_align =		__alignof__(struct bfq_io_cq),
-+	.elevator_attrs =	bfq_attrs,
-+	.elevator_name =	"bfq-sq",
-+	.elevator_owner =	THIS_MODULE,
-+};
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+static struct blkcg_policy blkcg_policy_bfq = {
-+	.dfl_cftypes		= bfq_blkg_files,
-+	.legacy_cftypes		= bfq_blkcg_legacy_files,
-+
-+	.cpd_alloc_fn		= bfq_cpd_alloc,
-+	.cpd_init_fn		= bfq_cpd_init,
-+	.cpd_bind_fn	        = bfq_cpd_init,
-+	.cpd_free_fn		= bfq_cpd_free,
-+
-+	.pd_alloc_fn		= bfq_pd_alloc,
-+	.pd_init_fn		= bfq_pd_init,
-+	.pd_offline_fn		= bfq_pd_offline,
-+	.pd_free_fn		= bfq_pd_free,
-+	.pd_reset_stats_fn	= bfq_pd_reset_stats,
-+};
-+#endif
-+
-+static int __init bfq_init(void)
-+{
-+	int ret;
-+	char msg[60] = "BFQ I/O-scheduler: v9";
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	ret = blkcg_policy_register(&blkcg_policy_bfq);
-+	if (ret)
-+		return ret;
-+#endif
-+
-+	ret = -ENOMEM;
-+	if (bfq_slab_setup())
-+		goto err_pol_unreg;
-+
-+	/*
-+	 * Times to load large popular applications for the typical
-+	 * systems installed on the reference devices (see the
-+	 * comments before the definition of the next
-+	 * array). Actually, we use slightly lower values, as the
-+	 * estimated peak rate tends to be smaller than the actual
-+	 * peak rate.  The reason for this last fact is that estimates
-+	 * are computed over much shorter time intervals than the long
-+	 * intervals typically used for benchmarking. Why? First, to
-+	 * adapt more quickly to variations. Second, because an I/O
-+	 * scheduler cannot rely on a peak-rate-evaluation workload to
-+	 * be run for a long time.
-+	 */
-+	ref_wr_duration[0] = msecs_to_jiffies(7000); /* actually 8 sec */
-+	ref_wr_duration[1] = msecs_to_jiffies(2500); /* actually 3 sec */
-+
-+	ret = elv_register(&iosched_bfq);
-+	if (ret)
-+		goto slab_kill;
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	strcat(msg, " (with cgroups support)");
-+#endif
-+	pr_info("%s", msg);
-+
-+	return 0;
-+
-+slab_kill:
-+	bfq_slab_kill();
-+err_pol_unreg:
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	blkcg_policy_unregister(&blkcg_policy_bfq);
-+#endif
-+	return ret;
-+}
-+
-+static void __exit bfq_exit(void)
-+{
-+	elv_unregister(&iosched_bfq);
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	blkcg_policy_unregister(&blkcg_policy_bfq);
-+#endif
-+	bfq_slab_kill();
-+}
-+
-+module_init(bfq_init);
-+module_exit(bfq_exit);
-+
-+MODULE_AUTHOR("Arianna Avanzini, Fabio Checconi, Paolo Valente");
-+MODULE_LICENSE("GPL");
-diff --git a/block/bfq.h b/block/bfq.h
-new file mode 100644
-index 000000000000..0177fc7205d7
---- /dev/null
-+++ b/block/bfq.h
-@@ -0,0 +1,1074 @@
-+/*
-+ * BFQ v9: data structures and common functions prototypes.
-+ *
-+ * Based on ideas and code from CFQ:
-+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
-+ *
-+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
-+ *		      Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2017 Paolo Valente <paolo.valente@linaro.org>
-+ */
-+
-+#ifndef _BFQ_H
-+#define _BFQ_H
-+
-+#include <linux/hrtimer.h>
-+#include <linux/blk-cgroup.h>
-+
-+/*
-+ * Define an alternative macro to compile cgroups support. This is one
-+ * of the steps needed to let bfq-mq share the files bfq-sched.c and
-+ * bfq-cgroup.c with bfq-sq. For bfq-mq, the macro
-+ * BFQ_GROUP_IOSCHED_ENABLED will be defined as a function of whether
-+ * the configuration option CONFIG_BFQ_MQ_GROUP_IOSCHED, and not
-+ * CONFIG_BFQ_GROUP_IOSCHED, is defined.
-+ */
-+#ifdef CONFIG_BFQ_SQ_GROUP_IOSCHED
-+#define BFQ_GROUP_IOSCHED_ENABLED
-+#endif
-+
-+#define BFQ_IOPRIO_CLASSES	3
-+#define BFQ_CL_IDLE_TIMEOUT	(HZ/5)
-+
-+#define BFQ_MIN_WEIGHT			1
-+#define BFQ_MAX_WEIGHT			1000
-+#define BFQ_WEIGHT_CONVERSION_COEFF	10
-+
-+#define BFQ_DEFAULT_QUEUE_IOPRIO	4
-+
-+#define BFQ_WEIGHT_LEGACY_DFL	100
-+#define BFQ_DEFAULT_GRP_IOPRIO	0
-+#define BFQ_DEFAULT_GRP_CLASS	IOPRIO_CLASS_BE
-+
-+/*
-+ * Soft real-time applications are extremely more latency sensitive
-+ * than interactive ones. Over-raise the weight of the former to
-+ * privilege them against the latter.
-+ */
-+#define BFQ_SOFTRT_WEIGHT_FACTOR	100
-+
-+struct bfq_entity;
-+
-+/**
-+ * struct bfq_service_tree - per ioprio_class service tree.
-+ *
-+ * Each service tree represents a B-WF2Q+ scheduler on its own.  Each
-+ * ioprio_class has its own independent scheduler, and so its own
-+ * bfq_service_tree.  All the fields are protected by the queue lock
-+ * of the containing bfqd.
-+ */
-+struct bfq_service_tree {
-+	/* tree for active entities (i.e., those backlogged) */
-+	struct rb_root active;
-+	/* tree for idle entities (i.e., not backlogged, with V <= F_i)*/
-+	struct rb_root idle;
-+
-+	struct bfq_entity *first_idle;	/* idle entity with minimum F_i */
-+	struct bfq_entity *last_idle;	/* idle entity with maximum F_i */
-+
-+	u64 vtime; /* scheduler virtual time */
-+	/* scheduler weight sum; active and idle entities contribute to it */
-+	unsigned long wsum;
-+};
-+
-+/**
-+ * struct bfq_sched_data - multi-class scheduler.
-+ *
-+ * bfq_sched_data is the basic scheduler queue.  It supports three
-+ * ioprio_classes, and can be used either as a toplevel queue or as an
-+ * intermediate queue in a hierarchical setup.
-+ *
-+ * The supported ioprio_classes are the same as in CFQ, in descending
-+ * priority order, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE.
-+ * Requests from higher priority queues are served before all the
-+ * requests from lower priority queues; among requests of the same
-+ * queue requests are served according to B-WF2Q+.
-+ *
-+ * The schedule is implemented by the service trees, plus the field
-+ * @next_in_service, which points to the entity on the active trees
-+ * that will be served next, if 1) no changes in the schedule occurs
-+ * before the current in-service entity is expired, 2) the in-service
-+ * queue becomes idle when it expires, and 3) if the entity pointed by
-+ * in_service_entity is not a queue, then the in-service child entity
-+ * of the entity pointed by in_service_entity becomes idle on
-+ * expiration. This peculiar definition allows for the following
-+ * optimization, not yet exploited: while a given entity is still in
-+ * service, we already know which is the best candidate for next
-+ * service among the other active entitities in the same parent
-+ * entity. We can then quickly compare the timestamps of the
-+ * in-service entity with those of such best candidate.
-+ *
-+ * All the fields are protected by the queue lock of the containing
-+ * bfqd.
-+ */
-+struct bfq_sched_data {
-+	struct bfq_entity *in_service_entity;  /* entity in service */
-+	/* head-of-the-line entity in the scheduler (see comments above) */
-+	struct bfq_entity *next_in_service;
-+	/* array of service trees, one per ioprio_class */
-+	struct bfq_service_tree service_tree[BFQ_IOPRIO_CLASSES];
-+	/* last time CLASS_IDLE was served */
-+	unsigned long bfq_class_idle_last_service;
-+
-+};
-+
-+/**
-+ * struct bfq_weight_counter - counter of the number of all active queues
-+ *                             with a given weight.
-+ */
-+struct bfq_weight_counter {
-+	unsigned int weight; /* weight of the queues this counter refers to */
-+	unsigned int num_active; /* nr of active queues with this weight */
-+	/*
-+	 * Weights tree member (see bfq_data's @queue_weights_tree)
-+	 */
-+	struct rb_node weights_node;
-+};
-+
-+/**
-+ * struct bfq_entity - schedulable entity.
-+ *
-+ * A bfq_entity is used to represent either a bfq_queue (leaf node in the
-+ * cgroup hierarchy) or a bfq_group into the upper level scheduler.  Each
-+ * entity belongs to the sched_data of the parent group in the cgroup
-+ * hierarchy.  Non-leaf entities have also their own sched_data, stored
-+ * in @my_sched_data.
-+ *
-+ * Each entity stores independently its priority values; this would
-+ * allow different weights on different devices, but this
-+ * functionality is not exported to userspace by now.  Priorities and
-+ * weights are updated lazily, first storing the new values into the
-+ * new_* fields, then setting the @prio_changed flag.  As soon as
-+ * there is a transition in the entity state that allows the priority
-+ * update to take place the effective and the requested priority
-+ * values are synchronized.
-+ *
-+ * Unless cgroups are used, the weight value is calculated from the
-+ * ioprio to export the same interface as CFQ.  When dealing with
-+ * ``well-behaved'' queues (i.e., queues that do not spend too much
-+ * time to consume their budget and have true sequential behavior, and
-+ * when there are no external factors breaking anticipation) the
-+ * relative weights at each level of the cgroups hierarchy should be
-+ * guaranteed.  All the fields are protected by the queue lock of the
-+ * containing bfqd.
-+ */
-+struct bfq_entity {
-+	struct rb_node rb_node; /* service_tree member */
-+
-+	/*
-+	 * Flag, true if the entity is on a tree (either the active or
-+	 * the idle one of its service_tree) or is in service.
-+	 */
-+	bool on_st;
-+
-+	u64 finish; /* B-WF2Q+ finish timestamp (aka F_i) */
-+	u64 start;  /* B-WF2Q+ start timestamp (aka S_i) */
-+
-+	/* tree the entity is enqueued into; %NULL if not on a tree */
-+	struct rb_root *tree;
-+
-+	/*
-+	 * minimum start time of the (active) subtree rooted at this
-+	 * entity; used for O(log N) lookups into active trees
-+	 */
-+	u64 min_start;
-+
-+	/* amount of service received during the last service slot */
-+	int service;
-+
-+	/* budget, used also to calculate F_i: F_i = S_i + @budget / @weight */
-+	int budget;
-+
-+	unsigned int weight;	 /* weight of the queue */
-+	unsigned int new_weight; /* next weight if a change is in progress */
-+
-+	/* original weight, used to implement weight boosting */
-+	unsigned int orig_weight;
-+
-+	/* parent entity, for hierarchical scheduling */
-+	struct bfq_entity *parent;
-+
-+	/*
-+	 * For non-leaf nodes in the hierarchy, the associated
-+	 * scheduler queue, %NULL on leaf nodes.
-+	 */
-+	struct bfq_sched_data *my_sched_data;
-+	/* the scheduler queue this entity belongs to */
-+	struct bfq_sched_data *sched_data;
-+
-+	/* flag, set to request a weight, ioprio or ioprio_class change  */
-+	int prio_changed;
-+
-+	/* flag, set if the entity is counted in groups_with_pending_reqs */
-+	bool in_groups_with_pending_reqs;
-+};
-+
-+struct bfq_group;
-+
-+/**
-+ * struct bfq_queue - leaf schedulable entity.
-+ *
-+ * A bfq_queue is a leaf request queue; it can be associated with an
-+ * io_context or more, if it  is  async or shared  between  cooperating
-+ * processes. @cgroup holds a reference to the cgroup, to be sure that it
-+ * does not disappear while a bfqq still references it (mostly to avoid
-+ * races between request issuing and task migration followed by cgroup
-+ * destruction).
-+ * All the fields are protected by the queue lock of the containing bfqd.
-+ */
-+struct bfq_queue {
-+	/* reference counter */
-+	int ref;
-+	/* parent bfq_data */
-+	struct bfq_data *bfqd;
-+
-+	/* current ioprio and ioprio class */
-+	unsigned short ioprio, ioprio_class;
-+	/* next ioprio and ioprio class if a change is in progress */
-+	unsigned short new_ioprio, new_ioprio_class;
-+
-+	/*
-+	 * Shared bfq_queue if queue is cooperating with one or more
-+	 * other queues.
-+	 */
-+	struct bfq_queue *new_bfqq;
-+	/* request-position tree member (see bfq_group's @rq_pos_tree) */
-+	struct rb_node pos_node;
-+	/* request-position tree root (see bfq_group's @rq_pos_tree) */
-+	struct rb_root *pos_root;
-+
-+	/* sorted list of pending requests */
-+	struct rb_root sort_list;
-+	/* if fifo isn't expired, next request to serve */
-+	struct request *next_rq;
-+	/* number of sync and async requests queued */
-+	int queued[2];
-+	/* number of sync and async requests currently allocated */
-+	int allocated[2];
-+	/* number of pending metadata requests */
-+	int meta_pending;
-+	/* fifo list of requests in sort_list */
-+	struct list_head fifo;
-+
-+	/* entity representing this queue in the scheduler */
-+	struct bfq_entity entity;
-+
-+	/* pointer to the weight counter associated with this queue */
-+	struct bfq_weight_counter *weight_counter;
-+
-+	/* maximum budget allowed from the feedback mechanism */
-+	int max_budget;
-+	/* budget expiration (in jiffies) */
-+	unsigned long budget_timeout;
-+
-+	/* number of requests on the dispatch list or inside driver */
-+	int dispatched;
-+
-+	unsigned int flags; /* status flags.*/
-+
-+	/* node for active/idle bfqq list inside parent bfqd */
-+	struct list_head bfqq_list;
-+
-+	/* bit vector: a 1 for each seeky requests in history */
-+	u32 seek_history;
-+
-+	/* node for the device's burst list */
-+	struct hlist_node burst_list_node;
-+
-+	/* position of the last request enqueued */
-+	sector_t last_request_pos;
-+
-+	/* Number of consecutive pairs of request completion and
-+	 * arrival, such that the queue becomes idle after the
-+	 * completion, but the next request arrives within an idle
-+	 * time slice; used only if the queue's IO_bound flag has been
-+	 * cleared.
-+	 */
-+	unsigned int requests_within_timer;
-+
-+	/* pid of the process owning the queue, used for logging purposes */
-+	pid_t pid;
-+
-+	/*
-+	 * Pointer to the bfq_io_cq owning the bfq_queue, set to %NULL
-+	 * if the queue is shared.
-+	 */
-+	struct bfq_io_cq *bic;
-+
-+	/* current maximum weight-raising time for this queue */
-+	unsigned long wr_cur_max_time;
-+	/*
-+	 * Minimum time instant such that, only if a new request is
-+	 * enqueued after this time instant in an idle @bfq_queue with
-+	 * no outstanding requests, then the task associated with the
-+	 * queue it is deemed as soft real-time (see the comments on
-+	 * the function bfq_bfqq_softrt_next_start())
-+	 */
-+	unsigned long soft_rt_next_start;
-+	/*
-+	 * Start time of the current weight-raising period if
-+	 * the @bfq-queue is being weight-raised, otherwise
-+	 * finish time of the last weight-raising period.
-+	 */
-+	unsigned long last_wr_start_finish;
-+	/* factor by which the weight of this queue is multiplied */
-+	unsigned int wr_coeff;
-+	/*
-+	 * Time of the last transition of the @bfq_queue from idle to
-+	 * backlogged.
-+	 */
-+	unsigned long last_idle_bklogged;
-+	/*
-+	 * Cumulative service received from the @bfq_queue since the
-+	 * last transition from idle to backlogged.
-+	 */
-+	unsigned long service_from_backlogged;
-+	/*
-+	 * Cumulative service received from the @bfq_queue since its
-+	 * last transition to weight-raised state.
-+	 */
-+	unsigned long service_from_wr;
-+	/*
-+	 * Value of wr start time when switching to soft rt
-+	 */
-+	unsigned long wr_start_at_switch_to_srt;
-+
-+	unsigned long split_time; /* time of last split */
-+
-+	unsigned long first_IO_time; /* time of first I/O for this queue */
-+
-+	/* max service rate measured so far */
-+	u32 max_service_rate;
-+	/*
-+	 * Ratio between the service received by bfqq while it is in
-+	 * service, and the cumulative service (of requests of other
-+	 * queues) that may be injected while bfqq is empty but still
-+	 * in service. To increase precision, the coefficient is
-+	 * measured in tenths of unit. Here are some example of (1)
-+	 * ratios, (2) resulting percentages of service injected
-+	 * w.r.t. to the total service dispatched while bfqq is in
-+	 * service, and (3) corresponding values of the coefficient:
-+	 * 1 (50%) -> 10
-+	 * 2 (33%) -> 20
-+	 * 10 (9%) -> 100
-+	 * 9.9 (9%) -> 99
-+	 * 1.5 (40%) -> 15
-+	 * 0.5 (66%) -> 5
-+	 * 0.1 (90%) -> 1
-+	 *
-+	 * So, if the coefficient is lower than 10, then
-+	 * injected service is more than bfqq service.
-+	 */
-+	unsigned int inject_coeff;
-+	/* amount of service injected in current service slot */
-+	unsigned int injected_service;
-+};
-+
-+/**
-+ * struct bfq_ttime - per process thinktime stats.
-+ */
-+struct bfq_ttime {
-+	u64 last_end_request; /* completion time of last request */
-+
-+	u64 ttime_total; /* total process thinktime */
-+	unsigned long ttime_samples; /* number of thinktime samples */
-+	u64 ttime_mean; /* average process thinktime */
-+
-+};
-+
-+/**
-+ * struct bfq_io_cq - per (request_queue, io_context) structure.
-+ */
-+struct bfq_io_cq {
-+	/* associated io_cq structure */
-+	struct io_cq icq; /* must be the first member */
-+	/* array of two process queues, the sync and the async */
-+	struct bfq_queue *bfqq[2];
-+	/* associated @bfq_ttime struct */
-+	struct bfq_ttime ttime;
-+	/* per (request_queue, blkcg) ioprio */
-+	int ioprio;
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	uint64_t blkcg_serial_nr; /* the current blkcg serial */
-+#endif
-+
-+	/*
-+	 * Snapshot of the has_short_time flag before merging; taken
-+	 * to remember its value while the queue is merged, so as to
-+	 * be able to restore it in case of split.
-+	 */
-+	bool saved_has_short_ttime;
-+	/*
-+	 * Same purpose as the previous two fields for the I/O bound
-+	 * classification of a queue.
-+	 */
-+	bool saved_IO_bound;
-+
-+	/*
-+	 * Same purpose as the previous fields for the value of the
-+	 * field keeping the queue's belonging to a large burst
-+	 */
-+	bool saved_in_large_burst;
-+	/*
-+	 * True if the queue belonged to a burst list before its merge
-+	 * with another cooperating queue.
-+	 */
-+	bool was_in_burst_list;
-+
-+	/*
-+	 * Similar to previous fields: save wr information.
-+	 */
-+	unsigned long saved_wr_coeff;
-+	unsigned long saved_last_wr_start_finish;
-+	unsigned long saved_wr_start_at_switch_to_srt;
-+	unsigned int saved_wr_cur_max_time;
-+};
-+
-+/**
-+ * struct bfq_data - per-device data structure.
-+ *
-+ * All the fields are protected by the @queue lock.
-+ */
-+struct bfq_data {
-+	/* request queue for the device */
-+	struct request_queue *queue;
-+
-+	/* root bfq_group for the device */
-+	struct bfq_group *root_group;
-+
-+	/*
-+	 * rbtree of weight counters of @bfq_queues, sorted by
-+	 * weight. Used to keep track of whether all @bfq_queues have
-+	 * the same weight. The tree contains one counter for each
-+	 * distinct weight associated to some active and not
-+	 * weight-raised @bfq_queue (see the comments to the functions
-+	 * bfq_weights_tree_[add|remove] for further details).
-+	 */
-+	struct rb_root queue_weights_tree;
-+
-+	/*
-+	 * Number of groups with at least one descendant process that
-+	 * has at least one request waiting for completion. Note that
-+	 * this accounts for also requests already dispatched, but not
-+	 * yet completed. Therefore this number of groups may differ
-+	 * (be larger) than the number of active groups, as a group is
-+	 * considered active only if its corresponding entity has
-+	 * descendant queues with at least one request queued. This
-+	 * number is used to decide whether a scenario is symmetric.
-+	 * For a detailed explanation see comments on the computation
-+	 * of the variable asymmetric_scenario in the function
-+	 * bfq_better_to_idle().
-+	 *
-+	 * However, it is hard to compute this number exactly, for
-+	 * groups with multiple descendant processes. Consider a group
-+	 * that is inactive, i.e., that has no descendant process with
-+	 * pending I/O inside BFQ queues. Then suppose that
-+	 * num_groups_with_pending_reqs is still accounting for this
-+	 * group, because the group has descendant processes with some
-+	 * I/O request still in flight. num_groups_with_pending_reqs
-+	 * should be decremented when the in-flight request of the
-+	 * last descendant process is finally completed (assuming that
-+	 * nothing else has changed for the group in the meantime, in
-+	 * terms of composition of the group and active/inactive state of child
-+	 * groups and processes). To accomplish this, an additional
-+	 * pending-request counter must be added to entities, and must
-+	 * be updated correctly. To avoid this additional field and operations,
-+	 * we resort to the following tradeoff between simplicity and
-+	 * accuracy: for an inactive group that is still counted in
-+	 * num_groups_with_pending_reqs, we decrement
-+	 * num_groups_with_pending_reqs when the first descendant
-+	 * process of the group remains with no request waiting for
-+	 * completion.
-+	 *
-+	 * Even this simpler decrement strategy requires a little
-+	 * carefulness: to avoid multiple decrements, we flag a group,
-+	 * more precisely an entity representing a group, as still
-+	 * counted in num_groups_with_pending_reqs when it becomes
-+	 * inactive. Then, when the first descendant queue of the
-+	 * entity remains with no request waiting for completion,
-+	 * num_groups_with_pending_reqs is decremented, and this flag
-+	 * is reset. After this flag is reset for the entity,
-+	 * num_groups_with_pending_reqs won't be decremented any
-+	 * longer in case a new descendant queue of the entity remains
-+	 * with no request waiting for completion.
-+	 */
-+	unsigned int num_groups_with_pending_reqs;
-+
-+	/*
-+	 * Per-class (RT, BE, IDLE) number of bfq_queues containing
-+	 * requests (including the queue in service, even if it is
-+	 * idling).
-+	 */
-+	unsigned int busy_queues[3];
-+	/* number of weight-raised busy @bfq_queues */
-+	int wr_busy_queues;
-+	/* number of queued requests */
-+	int queued;
-+	/* number of requests dispatched and waiting for completion */
-+	int rq_in_driver;
-+
-+	/*
-+	 * Maximum number of requests in driver in the last
-+	 * @hw_tag_samples completed requests.
-+	 */
-+	int max_rq_in_driver;
-+	/* number of samples used to calculate hw_tag */
-+	int hw_tag_samples;
-+	/* flag set to one if the driver is showing a queueing behavior */
-+	int hw_tag;
-+
-+	/* number of budgets assigned */
-+	int budgets_assigned;
-+
-+	/*
-+	 * Timer set when idling (waiting) for the next request from
-+	 * the queue in service.
-+	 */
-+	struct hrtimer idle_slice_timer;
-+	/* delayed work to restart dispatching on the request queue */
-+	struct work_struct unplug_work;
-+
-+	/* bfq_queue in service */
-+	struct bfq_queue *in_service_queue;
-+	/* bfq_io_cq (bic) associated with the @in_service_queue */
-+	struct bfq_io_cq *in_service_bic;
-+
-+	/* on-disk position of the last served request */
-+	sector_t last_position;
-+
-+	/* position of the last served request for the in-service queue */
-+	sector_t in_serv_last_pos;
-+
-+	/* time of last request completion (ns) */
-+	u64 last_completion;
-+
-+	/* time of first rq dispatch in current observation interval (ns) */
-+	u64 first_dispatch;
-+	/* time of last rq dispatch in current observation interval (ns) */
-+	u64 last_dispatch;
-+
-+	/* beginning of the last budget */
-+	ktime_t last_budget_start;
-+	/* beginning of the last idle slice */
-+	ktime_t last_idling_start;
-+
-+	/* number of samples in current observation interval */
-+	int peak_rate_samples;
-+	/* num of samples of seq dispatches in current observation interval */
-+	u32 sequential_samples;
-+	/* total num of sectors transferred in current observation interval */
-+	u64 tot_sectors_dispatched;
-+	/* max rq size seen during current observation interval (sectors) */
-+	u32 last_rq_max_size;
-+	/* time elapsed from first dispatch in current observ. interval (us) */
-+	u64 delta_from_first;
-+	/*
-+	 * Current estimate of the device peak rate, measured in
-+	 * [(sectors/usec) / 2^BFQ_RATE_SHIFT]. The left-shift by
-+	 * BFQ_RATE_SHIFT is performed to increase precision in
-+	 * fixed-point calculations.
-+	 */
-+	u32 peak_rate;
-+
-+	/* maximum budget allotted to a bfq_queue before rescheduling */
-+	int bfq_max_budget;
-+
-+	/* list of all the bfq_queues active on the device */
-+	struct list_head active_list;
-+	/* list of all the bfq_queues idle on the device */
-+	struct list_head idle_list;
-+
-+	/*
-+	 * Timeout for async/sync requests; when it fires, requests
-+	 * are served in fifo order.
-+	 */
-+	u64 bfq_fifo_expire[2];
-+	/* weight of backward seeks wrt forward ones */
-+	unsigned int bfq_back_penalty;
-+	/* maximum allowed backward seek */
-+	unsigned int bfq_back_max;
-+	/* maximum idling time */
-+	u32 bfq_slice_idle;
-+
-+	/* user-configured max budget value (0 for auto-tuning) */
-+	int bfq_user_max_budget;
-+	/*
-+	 * Timeout for bfq_queues to consume their budget; used to
-+	 * prevent seeky queues from imposing long latencies to
-+	 * sequential or quasi-sequential ones (this also implies that
-+	 * seeky queues cannot receive guarantees in the service
-+	 * domain; after a timeout they are charged for the time they
-+	 * have been in service, to preserve fairness among them, but
-+	 * without service-domain guarantees).
-+	 */
-+	unsigned int bfq_timeout;
-+
-+	/*
-+	 * Number of consecutive requests that must be issued within
-+	 * the idle time slice to set again idling to a queue which
-+	 * was marked as non-I/O-bound (see the definition of the
-+	 * IO_bound flag for further details).
-+	 */
-+	unsigned int bfq_requests_within_timer;
-+
-+	/*
-+	 * Force device idling whenever needed to provide accurate
-+	 * service guarantees, without caring about throughput
-+	 * issues. CAVEAT: this may even increase latencies, in case
-+	 * of useless idling for processes that did stop doing I/O.
-+	 */
-+	bool strict_guarantees;
-+
-+	/*
-+	 * Last time at which a queue entered the current burst of
-+	 * queues being activated shortly after each other; for more
-+	 * details about this and the following parameters related to
-+	 * a burst of activations, see the comments on the function
-+	 * bfq_handle_burst.
-+	 */
-+	unsigned long last_ins_in_burst;
-+	/*
-+	 * Reference time interval used to decide whether a queue has
-+	 * been activated shortly after @last_ins_in_burst.
-+	 */
-+	unsigned long bfq_burst_interval;
-+	/* number of queues in the current burst of queue activations */
-+	int burst_size;
-+
-+	/* common parent entity for the queues in the burst */
-+	struct bfq_entity *burst_parent_entity;
-+	/* Maximum burst size above which the current queue-activation
-+	 * burst is deemed as 'large'.
-+	 */
-+	unsigned long bfq_large_burst_thresh;
-+	/* true if a large queue-activation burst is in progress */
-+	bool large_burst;
-+	/*
-+	 * Head of the burst list (as for the above fields, more
-+	 * details in the comments on the function bfq_handle_burst).
-+	 */
-+	struct hlist_head burst_list;
-+
-+	/* if set to true, low-latency heuristics are enabled */
-+	bool low_latency;
-+	/*
-+	 * Maximum factor by which the weight of a weight-raised queue
-+	 * is multiplied.
-+	 */
-+	unsigned int bfq_wr_coeff;
-+	/* maximum duration of a weight-raising period (jiffies) */
-+	unsigned int bfq_wr_max_time;
-+
-+	/* Maximum weight-raising duration for soft real-time processes */
-+	unsigned int bfq_wr_rt_max_time;
-+	/*
-+	 * Minimum idle period after which weight-raising may be
-+	 * reactivated for a queue (in jiffies).
-+	 */
-+	unsigned int bfq_wr_min_idle_time;
-+	/*
-+	 * Minimum period between request arrivals after which
-+	 * weight-raising may be reactivated for an already busy async
-+	 * queue (in jiffies).
-+	 */
-+	unsigned long bfq_wr_min_inter_arr_async;
-+
-+	/* Max service-rate for a soft real-time queue, in sectors/sec */
-+	unsigned int bfq_wr_max_softrt_rate;
-+	/*
-+	 * Cached value of the product ref_rate*ref_wr_duration, used
-+	 * for computing the maximum duration of weight raising
-+	 * automatically.
-+	 */
-+	u64 rate_dur_prod;
-+
-+	/* fallback dummy bfqq for extreme OOM conditions */
-+	struct bfq_queue oom_bfqq;
-+};
-+
-+enum bfqq_state_flags {
-+	BFQ_BFQQ_FLAG_just_created = 0,	/* queue just allocated */
-+	BFQ_BFQQ_FLAG_busy,		/* has requests or is in service */
-+	BFQ_BFQQ_FLAG_wait_request,	/* waiting for a request */
-+	BFQ_BFQQ_FLAG_non_blocking_wait_rq, /*
-+					     * waiting for a request
-+					     * without idling the device
-+					     */
-+	BFQ_BFQQ_FLAG_must_alloc,	/* must be allowed rq alloc */
-+	BFQ_BFQQ_FLAG_fifo_expire,	/* FIFO checked in this slice */
-+	BFQ_BFQQ_FLAG_has_short_ttime,	/* queue has a short think time */
-+	BFQ_BFQQ_FLAG_sync,		/* synchronous queue */
-+	BFQ_BFQQ_FLAG_IO_bound,		/*
-+					 * bfqq has timed-out at least once
-+					 * having consumed at most 2/10 of
-+					 * its budget
-+					 */
-+	BFQ_BFQQ_FLAG_in_large_burst,	/*
-+					 * bfqq activated in a large burst,
-+					 * see comments to bfq_handle_burst.
-+					 */
-+	BFQ_BFQQ_FLAG_softrt_update,	/*
-+					 * may need softrt-next-start
-+					 * update
-+					 */
-+	BFQ_BFQQ_FLAG_coop,		/* bfqq is shared */
-+	BFQ_BFQQ_FLAG_split_coop	/* shared bfqq will be split */
-+};
-+
-+#define BFQ_BFQQ_FNS(name)						\
-+static void bfq_mark_bfqq_##name(struct bfq_queue *bfqq)		\
-+{									\
-+	(bfqq)->flags |= (1 << BFQ_BFQQ_FLAG_##name);			\
-+}									\
-+static void bfq_clear_bfqq_##name(struct bfq_queue *bfqq)		\
-+{									\
-+	(bfqq)->flags &= ~(1 << BFQ_BFQQ_FLAG_##name);			\
-+}									\
-+static int bfq_bfqq_##name(const struct bfq_queue *bfqq)		\
-+{									\
-+	return ((bfqq)->flags & (1 << BFQ_BFQQ_FLAG_##name)) != 0;	\
-+}
-+
-+BFQ_BFQQ_FNS(just_created);
-+BFQ_BFQQ_FNS(busy);
-+BFQ_BFQQ_FNS(wait_request);
-+BFQ_BFQQ_FNS(non_blocking_wait_rq);
-+BFQ_BFQQ_FNS(must_alloc);
-+BFQ_BFQQ_FNS(fifo_expire);
-+BFQ_BFQQ_FNS(has_short_ttime);
-+BFQ_BFQQ_FNS(sync);
-+BFQ_BFQQ_FNS(IO_bound);
-+BFQ_BFQQ_FNS(in_large_burst);
-+BFQ_BFQQ_FNS(coop);
-+BFQ_BFQQ_FNS(split_coop);
-+BFQ_BFQQ_FNS(softrt_update);
-+#undef BFQ_BFQQ_FNS
-+
-+/* Logging facilities. */
-+#ifdef CONFIG_BFQ_REDIRECT_TO_CONSOLE
-+
-+static const char *checked_dev_name(const struct device *dev)
-+{
-+	static const char nodev[] = "nodev";
-+
-+	if (dev)
-+		return dev_name(dev);
-+
-+	return nodev;
-+}
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+static struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
-+static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
-+
-+#define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	do {			\
-+	char __pbuf[128];						\
-+									\
-+	assert_spin_locked((bfqd)->queue->queue_lock);			\
-+	blkg_path(bfqg_to_blkg(bfqq_group(bfqq)), __pbuf, sizeof(__pbuf)); \
-+	pr_crit("%s bfq%d%c %s [%s] " fmt "\n",				\
-+		checked_dev_name((bfqd)->queue->backing_dev_info->dev),	\
-+		(bfqq)->pid,						\
-+		bfq_bfqq_sync((bfqq)) ? 'S' : 'A',			\
-+		__pbuf, __func__, ##args);				\
-+} while (0)
-+
-+#define bfq_log_bfqg(bfqd, bfqg, fmt, args...)	do {			\
-+	char __pbuf[128];						\
-+									\
-+	blkg_path(bfqg_to_blkg(bfqg), __pbuf, sizeof(__pbuf));		\
-+	pr_crit("%s %s [%s] " fmt "\n",					\
-+	checked_dev_name((bfqd)->queue->backing_dev_info->dev),		\
-+	__pbuf, __func__, ##args);					\
-+} while (0)
-+
-+#else /* BFQ_GROUP_IOSCHED_ENABLED */
-+
-+#define bfq_log_bfqq(bfqd, bfqq, fmt, args...)				\
-+	pr_crit("%s bfq%d%c [%s] " fmt "\n",				\
-+		checked_dev_name((bfqd)->queue->backing_dev_info->dev),	\
-+		(bfqq)->pid, bfq_bfqq_sync((bfqq)) ? 'S' : 'A',		\
-+		__func__, ##args)
-+#define bfq_log_bfqg(bfqd, bfqg, fmt, args...)		do {} while (0)
-+
-+#endif /* BFQ_GROUP_IOSCHED_ENABLED */
-+
-+#define bfq_log(bfqd, fmt, args...) \
-+	pr_crit("%s bfq [%s] " fmt "\n",				\
-+		checked_dev_name((bfqd)->queue->backing_dev_info->dev),	\
-+		__func__, ##args)
-+
-+#else /* CONFIG_BFQ_REDIRECT_TO_CONSOLE */
-+
-+#if !defined(CONFIG_BLK_DEV_IO_TRACE)
-+
-+/* Avoid possible "unused-variable" warning. See commit message. */
-+
-+#define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	((void) (bfqq))
-+
-+#define bfq_log_bfqg(bfqd, bfqg, fmt, args...)	((void) (bfqg))
-+
-+#define bfq_log(bfqd, fmt, args...)		do {} while (0)
-+
-+#else /* CONFIG_BLK_DEV_IO_TRACE */
-+
-+#include <linux/blktrace_api.h>
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+static struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
-+static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
-+
-+#define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	do {			\
-+	char __pbuf[128];						\
-+									\
-+	assert_spin_locked((bfqd)->queue->queue_lock);			\
-+	blkg_path(bfqg_to_blkg(bfqq_group(bfqq)), __pbuf, sizeof(__pbuf)); \
-+	blk_add_trace_msg((bfqd)->queue, "bfq%d%c %s [%s] " fmt, \
-+			  (bfqq)->pid,			  \
-+			  bfq_bfqq_sync((bfqq)) ? 'S' : 'A',	\
-+			  __pbuf, __func__, ##args);			\
-+} while (0)
-+
-+#define bfq_log_bfqg(bfqd, bfqg, fmt, args...)	do {			\
-+	char __pbuf[128];						\
-+									\
-+	blkg_path(bfqg_to_blkg(bfqg), __pbuf, sizeof(__pbuf));		\
-+	blk_add_trace_msg((bfqd)->queue, "%s [%s] " fmt, __pbuf, \
-+	__func__, ##args);	\
-+} while (0)
-+
-+#else /* BFQ_GROUP_IOSCHED_ENABLED */
-+
-+#define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	\
-+	blk_add_trace_msg((bfqd)->queue, "bfq%d%c [%s] " fmt, (bfqq)->pid, \
-+			bfq_bfqq_sync((bfqq)) ? 'S' : 'A',		\
-+				__func__, ##args)
-+#define bfq_log_bfqg(bfqd, bfqg, fmt, args...)		do {} while (0)
-+
-+#endif /* BFQ_GROUP_IOSCHED_ENABLED */
-+
-+#define bfq_log(bfqd, fmt, args...) \
-+	blk_add_trace_msg((bfqd)->queue, "bfq [%s] " fmt, __func__, ##args)
-+
-+#endif /* CONFIG_BLK_DEV_IO_TRACE */
-+#endif /* CONFIG_BFQ_REDIRECT_TO_CONSOLE */
-+
-+/* Expiration reasons. */
-+enum bfqq_expiration {
-+	BFQ_BFQQ_TOO_IDLE = 0,		/*
-+					 * queue has been idling for
-+					 * too long
-+					 */
-+	BFQ_BFQQ_BUDGET_TIMEOUT,	/* budget took too long to be used */
-+	BFQ_BFQQ_BUDGET_EXHAUSTED,	/* budget consumed */
-+	BFQ_BFQQ_NO_MORE_REQUESTS,	/* the queue has no more requests */
-+	BFQ_BFQQ_PREEMPTED		/* preemption in progress */
-+};
-+
-+
-+struct bfqg_stats {
-+#if defined(BFQ_GROUP_IOSCHED_ENABLED) &&  defined(CONFIG_DEBUG_BLK_CGROUP)
-+	/* number of ios merged */
-+	struct blkg_rwstat		merged;
-+	/* total time spent on device in ns, may not be accurate w/ queueing */
-+	struct blkg_rwstat		service_time;
-+	/* total time spent waiting in scheduler queue in ns */
-+	struct blkg_rwstat		wait_time;
-+	/* number of IOs queued up */
-+	struct blkg_rwstat		queued;
-+	/* total disk time and nr sectors dispatched by this group */
-+	struct blkg_stat		time;
-+	/* sum of number of ios queued across all samples */
-+	struct blkg_stat		avg_queue_size_sum;
-+	/* count of samples taken for average */
-+	struct blkg_stat		avg_queue_size_samples;
-+	/* how many times this group has been removed from service tree */
-+	struct blkg_stat		dequeue;
-+	/* total time spent waiting for it to be assigned a timeslice. */
-+	struct blkg_stat		group_wait_time;
-+	/* time spent idling for this blkcg_gq */
-+	struct blkg_stat		idle_time;
-+	/* total time with empty current active q with other requests queued */
-+	struct blkg_stat		empty_time;
-+	/* fields after this shouldn't be cleared on stat reset */
-+	uint64_t			start_group_wait_time;
-+	uint64_t			start_idle_time;
-+	uint64_t			start_empty_time;
-+	uint16_t			flags;
-+#endif /* BFQ_GROUP_IOSCHED_ENABLED && CONFIG_DEBUG_BLK_CGROUP */
-+};
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+/*
-+ * struct bfq_group_data - per-blkcg storage for the blkio subsystem.
-+ *
-+ * @ps: @blkcg_policy_storage that this structure inherits
-+ * @weight: weight of the bfq_group
-+ */
-+struct bfq_group_data {
-+	/* must be the first member */
-+	struct blkcg_policy_data pd;
-+
-+	unsigned int weight;
-+};
-+
-+/**
-+ * struct bfq_group - per (device, cgroup) data structure.
-+ * @entity: schedulable entity to insert into the parent group sched_data.
-+ * @sched_data: own sched_data, to contain child entities (they may be
-+ *              both bfq_queues and bfq_groups).
-+ * @bfqd: the bfq_data for the device this group acts upon.
-+ * @async_bfqq: array of async queues for all the tasks belonging to
-+ *              the group, one queue per ioprio value per ioprio_class,
-+ *              except for the idle class that has only one queue.
-+ * @async_idle_bfqq: async queue for the idle class (ioprio is ignored).
-+ * @my_entity: pointer to @entity, %NULL for the toplevel group; used
-+ *             to avoid too many special cases during group creation/
-+ *             migration.
-+ * @active_entities: number of active entities belonging to the group;
-+ *                   unused for the root group. Used to know whether there
-+ *                   are groups with more than one active @bfq_entity
-+ *                   (see the comments to the function
-+ *                   bfq_bfqq_may_idle()).
-+ * @rq_pos_tree: rbtree sorted by next_request position, used when
-+ *               determining if two or more queues have interleaving
-+ *               requests (see bfq_find_close_cooperator()).
-+ *
-+ * Each (device, cgroup) pair has its own bfq_group, i.e., for each cgroup
-+ * there is a set of bfq_groups, each one collecting the lower-level
-+ * entities belonging to the group that are acting on the same device.
-+ *
-+ * Locking works as follows:
-+ *    o @bfqd is protected by the queue lock, RCU is used to access it
-+ *      from the readers.
-+ *    o All the other fields are protected by the @bfqd queue lock.
-+ */
-+struct bfq_group {
-+	/* must be the first member */
-+	struct blkg_policy_data pd;
-+
-+	struct bfq_entity entity;
-+	struct bfq_sched_data sched_data;
-+
-+	void *bfqd;
-+
-+	struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
-+	struct bfq_queue *async_idle_bfqq;
-+
-+	struct bfq_entity *my_entity;
-+
-+	int active_entities;
-+
-+	struct rb_root rq_pos_tree;
-+
-+	struct bfqg_stats stats;
-+};
-+
-+#else
-+struct bfq_group {
-+	struct bfq_sched_data sched_data;
-+
-+	struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
-+	struct bfq_queue *async_idle_bfqq;
-+
-+	struct rb_root rq_pos_tree;
-+};
-+#endif
-+
-+static struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity);
-+
-+static unsigned int bfq_class_idx(struct bfq_entity *entity)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+
-+	return bfqq ? bfqq->ioprio_class - 1 :
-+		BFQ_DEFAULT_GRP_CLASS - 1;
-+}
-+
-+static unsigned int bfq_tot_busy_queues(struct bfq_data *bfqd)
-+{
-+	return bfqd->busy_queues[0] + bfqd->busy_queues[1] +
-+		bfqd->busy_queues[2];
-+}
-+
-+static struct bfq_service_tree *
-+bfq_entity_service_tree(struct bfq_entity *entity)
-+{
-+	struct bfq_sched_data *sched_data = entity->sched_data;
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+	unsigned int idx = bfq_class_idx(entity);
-+
-+	BUG_ON(idx >= BFQ_IOPRIO_CLASSES);
-+	BUG_ON(sched_data == NULL);
-+
-+	if (bfqq)
-+		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			     "%p %d",
-+			     sched_data->service_tree + idx, idx);
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+	else {
-+		struct bfq_group *bfqg =
-+			container_of(entity, struct bfq_group, entity);
-+
-+		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+			     "%p %d",
-+			     sched_data->service_tree + idx, idx);
-+	}
-+#endif
-+	return sched_data->service_tree + idx;
-+}
-+
-+static struct bfq_queue *bic_to_bfqq(struct bfq_io_cq *bic, bool is_sync)
-+{
-+	return bic->bfqq[is_sync];
-+}
-+
-+static void bic_set_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq,
-+			 bool is_sync)
-+{
-+	bic->bfqq[is_sync] = bfqq;
-+}
-+
-+static struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic)
-+{
-+	return bic->icq.q->elevator->elevator_data;
-+}
-+
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+
-+static struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq)
-+{
-+	struct bfq_entity *group_entity = bfqq->entity.parent;
-+
-+	if (!group_entity)
-+		group_entity = &bfqq->bfqd->root_group->entity;
-+
-+	return container_of(group_entity, struct bfq_group, entity);
-+}
-+
-+#else
-+
-+static struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq)
-+{
-+	return bfqq->bfqd->root_group;
-+}
-+
-+#endif
-+
-+static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio);
-+static void bfq_put_queue(struct bfq_queue *bfqq);
-+static void bfq_dispatch_insert(struct request_queue *q, struct request *rq);
-+static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd,
-+				       struct bio *bio, bool is_sync,
-+				       struct bfq_io_cq *bic);
-+static void bfq_end_wr_async_queues(struct bfq_data *bfqd,
-+				    struct bfq_group *bfqg);
-+#ifdef BFQ_GROUP_IOSCHED_ENABLED
-+static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);
-+#endif
-+static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq);
-+
-+#endif /* _BFQ_H */
-diff --git a/block/blk-mq.c b/block/blk-mq.c
-index e3c39ea8e17b..7a57368841f6 100644
---- a/block/blk-mq.c
-+++ b/block/blk-mq.c
-@@ -2878,6 +2878,8 @@ int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
- 		}
- 		if (ret)
- 			break;
-+		if (q->elevator && q->elevator->type->ops.mq.depth_updated)
-+			q->elevator->type->ops.mq.depth_updated(hctx);
- 	}
- 
- 	if (!ret)
-diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
-index 6980014357d4..8c4568ea6884 100644
---- a/include/linux/blkdev.h
-+++ b/include/linux/blkdev.h
-@@ -54,7 +54,7 @@ struct blk_stat_callback;
-  * Maximum number of blkcg policies allowed to be registered concurrently.
-  * Defined here to simplify include dependency.
-  */
--#define BLKCG_MAX_POLS		5
-+#define BLKCG_MAX_POLS		7
- 
- typedef void (rq_end_io_fn)(struct request *, blk_status_t);
- 
-@@ -127,6 +127,10 @@ typedef __u32 __bitwise req_flags_t;
- #define RQF_MQ_POLL_SLEPT	((__force req_flags_t)(1 << 20))
- /* ->timeout has been called, don't expire again */
- #define RQF_TIMED_OUT		((__force req_flags_t)(1 << 21))
-+/* DEBUG: rq in bfq-mq dispatch list */
-+#define RQF_DISP_LIST	((__force req_flags_t)(1 << 22))
-+/* DEBUG: rq had get_rq_private executed on it */
-+#define RQF_GOT	((__force req_flags_t)(1 << 23))
- 
- /* flags that prevent us from merging requests: */
- #define RQF_NOMERGE_FLAGS \
-diff --git a/include/linux/elevator.h b/include/linux/elevator.h
-index a02deea30185..a2bf4a6b9316 100644
---- a/include/linux/elevator.h
-+++ b/include/linux/elevator.h
-@@ -99,6 +99,7 @@ struct elevator_mq_ops {
- 	void (*exit_sched)(struct elevator_queue *);
- 	int (*init_hctx)(struct blk_mq_hw_ctx *, unsigned int);
- 	void (*exit_hctx)(struct blk_mq_hw_ctx *, unsigned int);
-+	void (*depth_updated)(struct blk_mq_hw_ctx *);
- 
- 	bool (*allow_merge)(struct request_queue *, struct request *, struct bio *);
- 	bool (*bio_merge)(struct blk_mq_hw_ctx *, struct bio *);