20 files changed, 160 insertions, 241 deletions

diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
index b3796a40a61a..59f46904cb11 100644
--- a/block/bfq-cgroup.c
+++ b/block/bfq-cgroup.c
@@ -1046,7 +1046,8 @@ struct blkcg_policy blkcg_policy_bfq = {
 struct cftype bfq_blkcg_legacy_files[] = {
 	{
 		.name = "bfq.weight",
-		.flags = CFTYPE_NOT_ON_ROOT,
+		.link_name = "weight",
+		.flags = CFTYPE_NOT_ON_ROOT | CFTYPE_SYMLINKED,
 		.seq_show = bfq_io_show_weight,
 		.write_u64 = bfq_io_set_weight_legacy,
 	},
@@ -1166,7 +1167,8 @@ struct cftype bfq_blkcg_legacy_files[] = {
 struct cftype bfq_blkg_files[] = {
 	{
 		.name = "bfq.weight",
-		.flags = CFTYPE_NOT_ON_ROOT,
+		.link_name = "weight",
+		.flags = CFTYPE_NOT_ON_ROOT | CFTYPE_SYMLINKED,
 		.seq_show = bfq_io_show_weight,
 		.write = bfq_io_set_weight,
 	},
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index b97b479e4f64..1f7127b03490 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -881,7 +881,7 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
 			blkg_free(new_blkg);
 		} else {
 			blkg = blkg_create(pos, q, new_blkg);
-			if (unlikely(IS_ERR(blkg))) {
+			if (IS_ERR(blkg)) {
 				ret = PTR_ERR(blkg);
 				goto fail_unlock;
 			}
diff --git a/block/blk-core.c b/block/blk-core.c
index 419d600e6637..8340f69670d8 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -282,35 +282,6 @@ void blk_set_queue_dying(struct request_queue *q)
 }
 EXPORT_SYMBOL_GPL(blk_set_queue_dying);
 
-/* Unconfigure the I/O scheduler and dissociate from the cgroup controller. */
-void blk_exit_queue(struct request_queue *q)
-{
-	/*
-	 * Since the I/O scheduler exit code may access cgroup information,
-	 * perform I/O scheduler exit before disassociating from the block
-	 * cgroup controller.
-	 */
-	if (q->elevator) {
-		ioc_clear_queue(q);
-		elevator_exit(q, q->elevator);
-		q->elevator = NULL;
-	}
-
-	/*
-	 * Remove all references to @q from the block cgroup controller before
-	 * restoring @q->queue_lock to avoid that restoring this pointer causes
-	 * e.g. blkcg_print_blkgs() to crash.
-	 */
-	blkcg_exit_queue(q);
-
-	/*
-	 * Since the cgroup code may dereference the @q->backing_dev_info
-	 * pointer, only decrease its reference count after having removed the
-	 * association with the block cgroup controller.
-	 */
-	bdi_put(q->backing_dev_info);
-}
-
 /**
  * blk_cleanup_queue - shutdown a request queue
  * @q: request queue to shutdown
@@ -346,17 +317,22 @@ void blk_cleanup_queue(struct request_queue *q)
 	del_timer_sync(&q->backing_dev_info->laptop_mode_wb_timer);
 	blk_sync_queue(q);
 
-	/*
-	 * I/O scheduler exit is only safe after the sysfs scheduler attribute
-	 * has been removed.
-	 */
-	WARN_ON_ONCE(q->kobj.state_in_sysfs);
-
-	blk_exit_queue(q);
-
 	if (queue_is_mq(q))
 		blk_mq_exit_queue(q);
 
+	/*
+	 * In theory, request pool of sched_tags belongs to request queue.
+	 * However, the current implementation requires tag_set for freeing
+	 * requests, so free the pool now.
+	 *
+	 * Queue has become frozen, there can't be any in-queue requests, so
+	 * it is safe to free requests now.
+	 */
+	mutex_lock(&q->sysfs_lock);
+	if (q->elevator)
+		blk_mq_sched_free_requests(q);
+	mutex_unlock(&q->sysfs_lock);
+
 	percpu_ref_exit(&q->q_usage_counter);
 
 	/* @q is and will stay empty, shutdown and put */
@@ -413,7 +389,7 @@ int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags)
 		smp_rmb();
 
 		wait_event(q->mq_freeze_wq,
-			   (atomic_read(&q->mq_freeze_depth) == 0 &&
+			   (!q->mq_freeze_depth &&
 			    (pm || (blk_pm_request_resume(q),
 				    !blk_queue_pm_only(q)))) ||
 			   blk_queue_dying(q));
@@ -503,6 +479,7 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
 	spin_lock_init(&q->queue_lock);
 
 	init_waitqueue_head(&q->mq_freeze_wq);
+	mutex_init(&q->mq_freeze_lock);
 
 	/*
 	 * Init percpu_ref in atomic mode so that it's faster to shutdown.
@@ -993,22 +970,8 @@ blk_qc_t generic_make_request(struct bio *bio)
 	 * yet.
 	 */
 	struct bio_list bio_list_on_stack[2];
-	blk_mq_req_flags_t flags = 0;
-	struct request_queue *q = bio->bi_disk->queue;
 	blk_qc_t ret = BLK_QC_T_NONE;
 
-	if (bio->bi_opf & REQ_NOWAIT)
-		flags = BLK_MQ_REQ_NOWAIT;
-	if (bio_flagged(bio, BIO_QUEUE_ENTERED))
-		blk_queue_enter_live(q);
-	else if (blk_queue_enter(q, flags) < 0) {
-		if (!blk_queue_dying(q) && (bio->bi_opf & REQ_NOWAIT))
-			bio_wouldblock_error(bio);
-		else
-			bio_io_error(bio);
-		return ret;
-	}
-
 	if (!generic_make_request_checks(bio))
 		goto out;
 
@@ -1045,22 +1008,11 @@ blk_qc_t generic_make_request(struct bio *bio)
 	bio_list_init(&bio_list_on_stack[0]);
 	current->bio_list = bio_list_on_stack;
 	do {
-		bool enter_succeeded = true;
-
-		if (unlikely(q != bio->bi_disk->queue)) {
-			if (q)
-				blk_queue_exit(q);
-			q = bio->bi_disk->queue;
-			flags = 0;
-			if (bio->bi_opf & REQ_NOWAIT)
-				flags = BLK_MQ_REQ_NOWAIT;
-			if (blk_queue_enter(q, flags) < 0) {
-				enter_succeeded = false;
-				q = NULL;
-			}
-		}
+		struct request_queue *q = bio->bi_disk->queue;
+		blk_mq_req_flags_t flags = bio->bi_opf & REQ_NOWAIT ?
+			BLK_MQ_REQ_NOWAIT : 0;
 
-		if (enter_succeeded) {
+		if (likely(blk_queue_enter(q, flags) == 0)) {
 			struct bio_list lower, same;
 
 			/* Create a fresh bio_list for all subordinate requests */
@@ -1068,6 +1020,8 @@ blk_qc_t generic_make_request(struct bio *bio)
 			bio_list_init(&bio_list_on_stack[0]);
 			ret = q->make_request_fn(q, bio);
 
+			blk_queue_exit(q);
+
 			/* sort new bios into those for a lower level
 			 * and those for the same level
 			 */
@@ -1094,8 +1048,6 @@ blk_qc_t generic_make_request(struct bio *bio)
 	current->bio_list = NULL; /* deactivate */
 
 out:
-	if (q)
-		blk_queue_exit(q);
 	return ret;
 }
 EXPORT_SYMBOL(generic_make_request);
@@ -1199,7 +1151,9 @@ static int blk_cloned_rq_check_limits(struct request_queue *q,
 				      struct request *rq)
 {
 	if (blk_rq_sectors(rq) > blk_queue_get_max_sectors(q, req_op(rq))) {
-		printk(KERN_ERR "%s: over max size limit.\n", __func__);
+		printk(KERN_ERR "%s: over max size limit. (%u > %u)\n",
+			__func__, blk_rq_sectors(rq),
+			blk_queue_get_max_sectors(q, req_op(rq)));
 		return -EIO;
 	}
 
@@ -1211,7 +1165,8 @@ static int blk_cloned_rq_check_limits(struct request_queue *q,
 	 */
 	blk_recalc_rq_segments(rq);
 	if (rq->nr_phys_segments > queue_max_segments(q)) {
-		printk(KERN_ERR "%s: over max segments limit.\n", __func__);
+		printk(KERN_ERR "%s: over max segments limit. (%hu > %hu)\n",
+			__func__, rq->nr_phys_segments, queue_max_segments(q));
 		return -EIO;
 	}
 
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 21e87a714a73..17713d7d98d5 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -12,23 +12,6 @@
 
 #include "blk.h"
 
-/*
- * Check if the two bvecs from two bios can be merged to one segment.  If yes,
- * no need to check gap between the two bios since the 1st bio and the 1st bvec
- * in the 2nd bio can be handled in one segment.
- */
-static inline bool bios_segs_mergeable(struct request_queue *q,
-		struct bio *prev, struct bio_vec *prev_last_bv,
-		struct bio_vec *next_first_bv)
-{
-	if (!biovec_phys_mergeable(q, prev_last_bv, next_first_bv))
-		return false;
-	if (prev->bi_seg_back_size + next_first_bv->bv_len >
-			queue_max_segment_size(q))
-		return false;
-	return true;
-}
-
 static inline bool bio_will_gap(struct request_queue *q,
 		struct request *prev_rq, struct bio *prev, struct bio *next)
 {
@@ -60,7 +43,7 @@ static inline bool bio_will_gap(struct request_queue *q,
 	 */
 	bio_get_last_bvec(prev, &pb);
 	bio_get_first_bvec(next, &nb);
-	if (bios_segs_mergeable(q, prev, &pb, &nb))
+	if (biovec_phys_mergeable(q, &pb, &nb))
 		return false;
 	return __bvec_gap_to_prev(q, &pb, nb.bv_offset);
 }
@@ -179,8 +162,7 @@ static unsigned get_max_segment_size(struct request_queue *q,
  * variables.
  */
 static bool bvec_split_segs(struct request_queue *q, struct bio_vec *bv,
-		unsigned *nsegs, unsigned *last_seg_size,
-		unsigned *front_seg_size, unsigned *sectors, unsigned max_segs)
+		unsigned *nsegs, unsigned *sectors, unsigned max_segs)
 {
 	unsigned len = bv->bv_len;
 	unsigned total_len = 0;
@@ -202,28 +184,12 @@ static bool bvec_split_segs(struct request_queue *q, struct bio_vec *bv,
 			break;
 	}
 
-	if (!new_nsegs)
-		return !!len;
-
-	/* update front segment size */
-	if (!*nsegs) {
-		unsigned first_seg_size;
-
-		if (new_nsegs == 1)
-			first_seg_size = get_max_segment_size(q, bv->bv_offset);
-		else
-			first_seg_size = queue_max_segment_size(q);
-
-		if (*front_seg_size < first_seg_size)
-			*front_seg_size = first_seg_size;
+	if (new_nsegs) {
+		*nsegs += new_nsegs;
+		if (sectors)
+			*sectors += total_len >> 9;
 	}
 
-	/* update other varibles */
-	*last_seg_size = seg_size;
-	*nsegs += new_nsegs;
-	if (sectors)
-		*sectors += total_len >> 9;
-
 	/* split in the middle of the bvec if len != 0 */
 	return !!len;
 }
@@ -235,8 +201,7 @@ static struct bio *blk_bio_segment_split(struct request_queue *q,
 {
 	struct bio_vec bv, bvprv, *bvprvp = NULL;
 	struct bvec_iter iter;
-	unsigned seg_size = 0, nsegs = 0, sectors = 0;
-	unsigned front_seg_size = bio->bi_seg_front_size;
+	unsigned nsegs = 0, sectors = 0;
 	bool do_split = true;
 	struct bio *new = NULL;
 	const unsigned max_sectors = get_max_io_size(q, bio);
@@ -260,8 +225,6 @@ static struct bio *blk_bio_segment_split(struct request_queue *q,
 				/* split in the middle of bvec */
 				bv.bv_len = (max_sectors - sectors) << 9;
 				bvec_split_segs(q, &bv, &nsegs,
-						&seg_size,
-						&front_seg_size,
 						&sectors, max_segs);
 			}
 			goto split;
@@ -275,12 +238,9 @@ static struct bio *blk_bio_segment_split(struct request_queue *q,
 
 		if (bv.bv_offset + bv.bv_len <= PAGE_SIZE) {
 			nsegs++;
-			seg_size = bv.bv_len;
 			sectors += bv.bv_len >> 9;
-			if (nsegs == 1 && seg_size > front_seg_size)
-				front_seg_size = seg_size;
-		} else if (bvec_split_segs(q, &bv, &nsegs, &seg_size,
-				    &front_seg_size, &sectors, max_segs)) {
+		} else if (bvec_split_segs(q, &bv, &nsegs, &sectors,
+				max_segs)) {
 			goto split;
 		}
 	}
@@ -295,10 +255,6 @@ split:
 			bio = new;
 	}
 
-	bio->bi_seg_front_size = front_seg_size;
-	if (seg_size > bio->bi_seg_back_size)
-		bio->bi_seg_back_size = seg_size;
-
 	return do_split ? new : NULL;
 }
 
@@ -353,18 +309,13 @@ EXPORT_SYMBOL(blk_queue_split);
 static unsigned int __blk_recalc_rq_segments(struct request_queue *q,
 					     struct bio *bio)
 {
-	struct bio_vec uninitialized_var(bv), bvprv = { NULL };
-	unsigned int seg_size, nr_phys_segs;
-	unsigned front_seg_size;
-	struct bio *fbio, *bbio;
+	unsigned int nr_phys_segs = 0;
 	struct bvec_iter iter;
-	bool new_bio = false;
+	struct bio_vec bv;
 
 	if (!bio)
 		return 0;
 
-	front_seg_size = bio->bi_seg_front_size;
-
 	switch (bio_op(bio)) {
 	case REQ_OP_DISCARD:
 	case REQ_OP_SECURE_ERASE:
@@ -374,42 +325,11 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q,
 		return 1;
 	}
 
-	fbio = bio;
-	seg_size = 0;
-	nr_phys_segs = 0;
 	for_each_bio(bio) {
-		bio_for_each_bvec(bv, bio, iter) {
-			if (new_bio) {
-				if (seg_size + bv.bv_len
-				    > queue_max_segment_size(q))
-					goto new_segment;
-				if (!biovec_phys_mergeable(q, &bvprv, &bv))
-					goto new_segment;
-
-				seg_size += bv.bv_len;
-
-				if (nr_phys_segs == 1 && seg_size >
-						front_seg_size)
-					front_seg_size = seg_size;
-
-				continue;
-			}
-new_segment:
-			bvec_split_segs(q, &bv, &nr_phys_segs, &seg_size,
-					&front_seg_size, NULL, UINT_MAX);
-			new_bio = false;
-		}
-		bbio = bio;
-		if (likely(bio->bi_iter.bi_size)) {
-			bvprv = bv;
-			new_bio = true;
-		}
+		bio_for_each_bvec(bv, bio, iter)
+			bvec_split_segs(q, &bv, &nr_phys_segs, NULL, UINT_MAX);
 	}
 
-	fbio->bi_seg_front_size = front_seg_size;
-	if (seg_size > bbio->bi_seg_back_size)
-		bbio->bi_seg_back_size = seg_size;
-
 	return nr_phys_segs;
 }
 
@@ -429,24 +349,6 @@ void blk_recount_segments(struct request_queue *q, struct bio *bio)
 	bio_set_flag(bio, BIO_SEG_VALID);
 }
 
-static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio,
-				   struct bio *nxt)
-{
-	struct bio_vec end_bv = { NULL }, nxt_bv;
-
-	if (bio->bi_seg_back_size + nxt->bi_seg_front_size >
-	    queue_max_segment_size(q))
-		return 0;
-
-	if (!bio_has_data(bio))
-		return 1;
-
-	bio_get_last_bvec(bio, &end_bv);
-	bio_get_first_bvec(nxt, &nxt_bv);
-
-	return biovec_phys_mergeable(q, &end_bv, &nxt_bv);
-}
-
 static inline struct scatterlist *blk_next_sg(struct scatterlist **sg,
 		struct scatterlist *sglist)
 {
@@ -706,8 +608,6 @@ static int ll_merge_requests_fn(struct request_queue *q, struct request *req,
 				struct request *next)
 {
 	int total_phys_segments;
-	unsigned int seg_size =
-		req->biotail->bi_seg_back_size + next->bio->bi_seg_front_size;
 
 	if (req_gap_back_merge(req, next->bio))
 		return 0;
@@ -720,14 +620,6 @@ static int ll_merge_requests_fn(struct request_queue *q, struct request *req,
 		return 0;
 
 	total_phys_segments = req->nr_phys_segments + next->nr_phys_segments;
-	if (blk_phys_contig_segment(q, req->biotail, next->bio)) {
-		if (req->nr_phys_segments == 1)
-			req->bio->bi_seg_front_size = seg_size;
-		if (next->nr_phys_segments == 1)
-			next->biotail->bi_seg_back_size = seg_size;
-		total_phys_segments--;
-	}
-
 	if (total_phys_segments > queue_max_segments(q))
 		return 0;
 
diff --git a/block/blk-mq-cpumap.c b/block/blk-mq-cpumap.c
index 48bebf00a5f3..f945621a0e8f 100644
--- a/block/blk-mq-cpumap.c
+++ b/block/blk-mq-cpumap.c
@@ -42,8 +42,8 @@ int blk_mq_map_queues(struct blk_mq_queue_map *qmap)
 		/*
 		 * First do sequential mapping between CPUs and queues.
 		 * In case we still have CPUs to map, and we have some number of
-		 * threads per cores then map sibling threads to the same queue for
-		 * performace optimizations.
+		 * threads per cores then map sibling threads to the same queue
+		 * for performance optimizations.
 		 */
 		if (cpu < nr_queues) {
 			map[cpu] = cpu_to_queue_index(qmap, nr_queues, cpu);
@@ -60,7 +60,11 @@ int blk_mq_map_queues(struct blk_mq_queue_map *qmap)
 }
 EXPORT_SYMBOL_GPL(blk_mq_map_queues);
 
-/*
+/**
+ * blk_mq_hw_queue_to_node - Look up the memory node for a hardware queue index
+ * @qmap: CPU to hardware queue map.
+ * @index: hardware queue index.
+ *
  * We have no quick way of doing reverse lookups. This is only used at
  * queue init time, so runtime isn't important.
  */
diff --git a/block/blk-mq-pci.c b/block/blk-mq-pci.c
index ad4545a2a98b..b595a94c4d16 100644
--- a/block/blk-mq-pci.c
+++ b/block/blk-mq-pci.c
@@ -13,7 +13,7 @@
 
 /**
  * blk_mq_pci_map_queues - provide a default queue mapping for PCI device
- * @set:	tagset to provide the mapping for
+ * @qmap:	CPU to hardware queue map.
  * @pdev:	PCI device associated with @set.
  * @offset:	Offset to use for the pci irq vector
  *
diff --git a/block/blk-mq-rdma.c b/block/blk-mq-rdma.c
index cc921e6ba709..14f968e58b8f 100644
--- a/block/blk-mq-rdma.c
+++ b/block/blk-mq-rdma.c
@@ -8,8 +8,8 @@
 
 /**
  * blk_mq_rdma_map_queues - provide a default queue mapping for rdma device
- * @set:	tagset to provide the mapping for
- * @dev:	rdma device associated with @set.
+ * @map:	CPU to hardware queue map.
+ * @dev:	rdma device to provide a mapping for.
  * @first_vec:	first interrupt vectors to use for queues (usually 0)
  *
  * This function assumes the rdma device @dev has at least as many available
diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index 74c6bb871f7e..500cb04901cc 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -475,14 +475,18 @@ static int blk_mq_sched_alloc_tags(struct request_queue *q,
 	return ret;
 }
 
+/* called in queue's release handler, tagset has gone away */
 static void blk_mq_sched_tags_teardown(struct request_queue *q)
 {
-	struct blk_mq_tag_set *set = q->tag_set;
 	struct blk_mq_hw_ctx *hctx;
 	int i;
 
-	queue_for_each_hw_ctx(q, hctx, i)
-		blk_mq_sched_free_tags(set, hctx, i);
+	queue_for_each_hw_ctx(q, hctx, i) {
+		if (hctx->sched_tags) {
+			blk_mq_free_rq_map(hctx->sched_tags);
+			hctx->sched_tags = NULL;
+		}
+	}
 }
 
 int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e)
@@ -523,6 +527,7 @@ int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e)
 			ret = e->ops.init_hctx(hctx, i);
 			if (ret) {
 				eq = q->elevator;
+				blk_mq_sched_free_requests(q);
 				blk_mq_exit_sched(q, eq);
 				kobject_put(&eq->kobj);
 				return ret;
@@ -534,11 +539,30 @@ int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e)
 	return 0;
 
 err:
+	blk_mq_sched_free_requests(q);
 	blk_mq_sched_tags_teardown(q);
 	q->elevator = NULL;
 	return ret;
 }
 
+/*
+ * called in either blk_queue_cleanup or elevator_switch, tagset
+ * is required for freeing requests
+ */
+void blk_mq_sched_free_requests(struct request_queue *q)
+{
+	struct blk_mq_hw_ctx *hctx;
+	int i;
+
+	lockdep_assert_held(&q->sysfs_lock);
+	WARN_ON(!q->elevator);
+
+	queue_for_each_hw_ctx(q, hctx, i) {
+		if (hctx->sched_tags)
+			blk_mq_free_rqs(q->tag_set, hctx->sched_tags, i);
+	}
+}
+
 void blk_mq_exit_sched(struct request_queue *q, struct elevator_queue *e)
 {
 	struct blk_mq_hw_ctx *hctx;
diff --git a/block/blk-mq-sched.h b/block/blk-mq-sched.h
index c7bdb52367ac..3cf92cbbd8ac 100644
--- a/block/blk-mq-sched.h
+++ b/block/blk-mq-sched.h
@@ -28,6 +28,7 @@ void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx);
 
 int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e);
 void blk_mq_exit_sched(struct request_queue *q, struct elevator_queue *e);
+void blk_mq_sched_free_requests(struct request_queue *q);
 
 static inline bool
 blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio)
diff --git a/block/blk-mq-virtio.c b/block/blk-mq-virtio.c
index 75a52c18a8f6..488341628256 100644
--- a/block/blk-mq-virtio.c
+++ b/block/blk-mq-virtio.c
@@ -11,8 +11,8 @@
 
 /**
  * blk_mq_virtio_map_queues - provide a default queue mapping for virtio device
- * @set:	tagset to provide the mapping for
- * @vdev:	virtio device associated with @set.
+ * @qmap:	CPU to hardware queue map.
+ * @vdev:	virtio device to provide a mapping for.
  * @first_vec:	first interrupt vectors to use for queues (usually 0)
  *
  * This function assumes the virtio device @vdev has at least as many available
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 08a6248d8536..ce0f5f4ede70 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -144,13 +144,14 @@ void blk_mq_in_flight_rw(struct request_queue *q, struct hd_struct *part,
 
 void blk_freeze_queue_start(struct request_queue *q)
 {
-	int freeze_depth;
-
-	freeze_depth = atomic_inc_return(&q->mq_freeze_depth);
-	if (freeze_depth == 1) {
+	mutex_lock(&q->mq_freeze_lock);
+	if (++q->mq_freeze_depth == 1) {
 		percpu_ref_kill(&q->q_usage_counter);
+		mutex_unlock(&q->mq_freeze_lock);
 		if (queue_is_mq(q))
 			blk_mq_run_hw_queues(q, false);
+	} else {
+		mutex_unlock(&q->mq_freeze_lock);
 	}
 }
 EXPORT_SYMBOL_GPL(blk_freeze_queue_start);
@@ -199,14 +200,14 @@ EXPORT_SYMBOL_GPL(blk_mq_freeze_queue);
 
 void blk_mq_unfreeze_queue(struct request_queue *q)
 {
-	int freeze_depth;
-
-	freeze_depth = atomic_dec_return(&q->mq_freeze_depth);
-	WARN_ON_ONCE(freeze_depth < 0);
-	if (!freeze_depth) {
+	mutex_lock(&q->mq_freeze_lock);
+	q->mq_freeze_depth--;
+	WARN_ON_ONCE(q->mq_freeze_depth < 0);
+	if (!q->mq_freeze_depth) {
 		percpu_ref_resurrect(&q->q_usage_counter);
 		wake_up_all(&q->mq_freeze_wq);
 	}
+	mutex_unlock(&q->mq_freeze_lock);
 }
 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue);
 
@@ -2864,7 +2865,7 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
 		goto err_exit;
 
 	if (blk_mq_alloc_ctxs(q))
-		goto err_exit;
+		goto err_poll;
 
 	/* init q->mq_kobj and sw queues' kobjects */
 	blk_mq_sysfs_init(q);
@@ -2928,6 +2929,9 @@ err_hctxs:
 	kfree(q->queue_hw_ctx);
 err_sys_init:
 	blk_mq_sysfs_deinit(q);
+err_poll:
+	blk_stat_free_callback(q->poll_cb);
+	q->poll_cb = NULL;
 err_exit:
 	q->mq_ops = NULL;
 	return ERR_PTR(-ENOMEM);
diff --git a/block/blk-rq-qos.c b/block/blk-rq-qos.c
index 3f55b56f24bc..659ccb8b693f 100644
--- a/block/blk-rq-qos.c
+++ b/block/blk-rq-qos.c
@@ -209,9 +209,10 @@ static int rq_qos_wake_function(struct wait_queue_entry *curr,
 
 /**
  * rq_qos_wait - throttle on a rqw if we need to
- * @private_data - caller provided specific data
- * @acquire_inflight_cb - inc the rqw->inflight counter if we can
- * @cleanup_cb - the callback to cleanup in case we race with a waker
+ * @rqw: rqw to throttle on
+ * @private_data: caller provided specific data
+ * @acquire_inflight_cb: inc the rqw->inflight counter if we can
+ * @cleanup_cb: the callback to cleanup in case we race with a waker
  *
  * This provides a uniform place for the rq_qos users to do their throttling.
  * Since you can end up with a lot of things sleeping at once, this manages the
diff --git a/block/blk-settings.c b/block/blk-settings.c
index 3facc41476be..2ae348c101a0 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -310,6 +310,9 @@ void blk_queue_max_segment_size(struct request_queue *q, unsigned int max_size)
 		       __func__, max_size);
 	}
 
+	/* see blk_queue_virt_boundary() for the explanation */
+	WARN_ON_ONCE(q->limits.virt_boundary_mask);
+
 	q->limits.max_segment_size = max_size;
 }
 EXPORT_SYMBOL(blk_queue_max_segment_size);
@@ -742,6 +745,14 @@ EXPORT_SYMBOL(blk_queue_segment_boundary);
 void blk_queue_virt_boundary(struct request_queue *q, unsigned long mask)
 {
 	q->limits.virt_boundary_mask = mask;
+
+	/*
+	 * Devices that require a virtual boundary do not support scatter/gather
+	 * I/O natively, but instead require a descriptor list entry for each
+	 * page (which might not be idential to the Linux PAGE_SIZE).  Because
+	 * of that they are not limited by our notion of "segment size".
+	 */
+	q->limits.max_segment_size = UINT_MAX;
 }
 EXPORT_SYMBOL(blk_queue_virt_boundary);
 
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index a16a02c52a85..977c659dcd18 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -840,6 +840,36 @@ static void blk_free_queue_rcu(struct rcu_head *rcu_head)
 	kmem_cache_free(blk_requestq_cachep, q);
 }
 
+/* Unconfigure the I/O scheduler and dissociate from the cgroup controller. */
+static void blk_exit_queue(struct request_queue *q)
+{
+	/*
+	 * Since the I/O scheduler exit code may access cgroup information,
+	 * perform I/O scheduler exit before disassociating from the block
+	 * cgroup controller.
+	 */
+	if (q->elevator) {
+		ioc_clear_queue(q);
+		__elevator_exit(q, q->elevator);
+		q->elevator = NULL;
+	}
+
+	/*
+	 * Remove all references to @q from the block cgroup controller before
+	 * restoring @q->queue_lock to avoid that restoring this pointer causes
+	 * e.g. blkcg_print_blkgs() to crash.
+	 */
+	blkcg_exit_queue(q);
+
+	/*
+	 * Since the cgroup code may dereference the @q->backing_dev_info
+	 * pointer, only decrease its reference count after having removed the
+	 * association with the block cgroup controller.
+	 */
+	bdi_put(q->backing_dev_info);
+}
+
+
 /**
  * __blk_release_queue - release a request queue
  * @work: pointer to the release_work member of the request queue to be released
@@ -860,23 +890,10 @@ static void __blk_release_queue(struct work_struct *work)
 		blk_stat_remove_callback(q, q->poll_cb);
 	blk_stat_free_callback(q->poll_cb);
 
-	if (!blk_queue_dead(q)) {
-		/*
-		 * Last reference was dropped without having called
-		 * blk_cleanup_queue().
-		 */
-		WARN_ONCE(blk_queue_init_done(q),
-			  "request queue %p has been registered but blk_cleanup_queue() has not been called for that queue\n",
-			  q);
-		blk_exit_queue(q);
-	}
-
-	WARN(blk_queue_root_blkg(q),
-	     "request queue %p is being released but it has not yet been removed from the blkcg controller\n",
-	     q);
-
 	blk_free_queue_stats(q->stats);
 
+	blk_exit_queue(q);
+
 	blk_queue_free_zone_bitmaps(q);
 
 	if (queue_is_mq(q))
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 1b97a73d2fb1..9ea7c0ecad10 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -1220,7 +1220,7 @@ static bool throtl_can_upgrade(struct throtl_data *td,
 	struct throtl_grp *this_tg);
 /**
  * throtl_pending_timer_fn - timer function for service_queue->pending_timer
- * @arg: the throtl_service_queue being serviced
+ * @t: the pending_timer member of the throtl_service_queue being serviced
  *
  * This timer is armed when a child throtl_grp with active bio's become
  * pending and queued on the service_queue's pending_tree and expires when
diff --git a/block/blk.h b/block/blk.h
index e27fd1512e4b..7814aa207153 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -6,6 +6,7 @@
 #include <linux/blk-mq.h>
 #include <xen/xen.h>
 #include "blk-mq.h"
+#include "blk-mq-sched.h"
 
 /* Max future timer expiry for timeouts */
 #define BLK_MAX_TIMEOUT		(5 * HZ)
@@ -50,7 +51,6 @@ struct blk_flush_queue *blk_alloc_flush_queue(struct request_queue *q,
 		int node, int cmd_size, gfp_t flags);
 void blk_free_flush_queue(struct blk_flush_queue *q);
 
-void blk_exit_queue(struct request_queue *q);
 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
 			struct bio *bio);
 void blk_freeze_queue(struct request_queue *q);
@@ -177,10 +177,17 @@ void blk_insert_flush(struct request *rq);
 int elevator_init_mq(struct request_queue *q);
 int elevator_switch_mq(struct request_queue *q,
 			      struct elevator_type *new_e);
-void elevator_exit(struct request_queue *, struct elevator_queue *);
+void __elevator_exit(struct request_queue *, struct elevator_queue *);
 int elv_register_queue(struct request_queue *q);
 void elv_unregister_queue(struct request_queue *q);
 
+static inline void elevator_exit(struct request_queue *q,
+		struct elevator_queue *e)
+{
+	blk_mq_sched_free_requests(q);
+	__elevator_exit(q, e);
+}
+
 struct hd_struct *__disk_get_part(struct gendisk *disk, int partno);
 
 #ifdef CONFIG_FAIL_IO_TIMEOUT
diff --git a/block/bsg-lib.c b/block/bsg-lib.c
index b898a1cdf872..785dd58947f1 100644
--- a/block/bsg-lib.c
+++ b/block/bsg-lib.c
@@ -354,6 +354,7 @@ static const struct blk_mq_ops bsg_mq_ops = {
  * @dev: device to attach bsg device to
  * @name: device to give bsg device
  * @job_fn: bsg job handler
+ * @timeout: timeout handler function pointer
  * @dd_job_size: size of LLD data needed for each job
  */
 struct request_queue *bsg_setup_queue(struct device *dev, const char *name,
diff --git a/block/elevator.c b/block/elevator.c
index ec55d5fc0b3e..2f17d66d0e61 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -178,7 +178,7 @@ static void elevator_release(struct kobject *kobj)
 	kfree(e);
 }
 
-void elevator_exit(struct request_queue *q, struct elevator_queue *e)
+void __elevator_exit(struct request_queue *q, struct elevator_queue *e)
 {
 	mutex_lock(&e->sysfs_lock);
 	if (e->type->ops.exit_sched)
diff --git a/block/genhd.c b/block/genhd.c
index ad6826628e79..24654e1d83e6 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -532,8 +532,8 @@ void blk_free_devt(dev_t devt)
 	}
 }
 
-/**
- *	We invalidate devt by assigning NULL pointer for devt in idr.
+/*
+ * We invalidate devt by assigning NULL pointer for devt in idr.
  */
 void blk_invalidate_devt(dev_t devt)
 {
diff --git a/block/partitions/ldm.c b/block/partitions/ldm.c
index 6db573f33219..fe5d970e2e60 100644
--- a/block/partitions/ldm.c
+++ b/block/partitions/ldm.c
@@ -19,7 +19,7 @@
 #include "check.h"
 #include "msdos.h"
 
-/**
+/*
  * ldm_debug/info/error/crit - Output an error message
  * @f:    A printf format string containing the message
  * @...:  Variables to substitute into @f