Merge branch 'for-4.13/block' of git://git.kernel.dk/linux-block

Pull core block/IO updates from Jens Axboe:
 "This is the main pull request for the block layer for 4.13. Not a huge
  round in terms of features, but there's a lot of churn related to some
  core cleanups.

  Note this depends on the UUID tree pull request, that Christoph
  already sent out.

  This pull request contains:

   - A series from Christoph, unifying the error/stats codes in the
     block layer. We now use blk_status_t everywhere, instead of using
     different schemes for different places.

   - Also from Christoph, some cleanups around request allocation and IO
     scheduler interactions in blk-mq.

   - And yet another series from Christoph, cleaning up how we handle
     and do bounce buffering in the block layer.

   - A blk-mq debugfs series from Bart, further improving on the support
     we have for exporting internal information to aid debugging IO
     hangs or stalls.

   - Also from Bart, a series that cleans up the request initialization
     differences across types of devices.

   - A series from Goldwyn Rodrigues, allowing the block layer to return
     failure if we will block and the user asked for non-blocking.

   - Patch from Hannes for supporting setting loop devices block size to
     that of the underlying device.

   - Two series of patches from Javier, fixing various issues with
     lightnvm, particular around pblk.

   - A series from me, adding support for write hints. This comes with
     NVMe support as well, so applications can help guide data placement
     on flash to improve performance, latencies, and write
     amplification.

   - A series from Ming, improving and hardening blk-mq support for
     stopping/starting and quiescing hardware queues.

   - Two pull requests for NVMe updates. Nothing major on the feature
     side, but lots of cleanups and bug fixes. From the usual crew.

   - A series from Neil Brown, greatly improving the bio rescue set
     support. Most notably, this kills the bio rescue work queues, if we
     don't really need them.

   - Lots of other little bug fixes that are all over the place"

* 'for-4.13/block' of git://git.kernel.dk/linux-block: (217 commits)
  lightnvm: pblk: set line bitmap check under debug
  lightnvm: pblk: verify that cache read is still valid
  lightnvm: pblk: add initialization check
  lightnvm: pblk: remove target using async. I/Os
  lightnvm: pblk: use vmalloc for GC data buffer
  lightnvm: pblk: use right metadata buffer for recovery
  lightnvm: pblk: schedule if data is not ready
  lightnvm: pblk: remove unused return variable
  lightnvm: pblk: fix double-free on pblk init
  lightnvm: pblk: fix bad le64 assignations
  nvme: Makefile: remove dead build rule
  blk-mq: map all HWQ also in hyperthreaded system
  nvmet-rdma: register ib_client to not deadlock in device removal
  nvme_fc: fix error recovery on link down.
  nvmet_fc: fix crashes on bad opcodes
  nvme_fc: Fix crash when nvme controller connection fails.
  nvme_fc: replace ioabort msleep loop with completion
  nvme_fc: fix double calls to nvme_cleanup_cmd()
  nvme-fabrics: verify that a controller returns the correct NQN
  nvme: simplify nvme_dev_attrs_are_visible
  ...

30 files changed, 854 insertions, 671 deletions

diff --git a/block/badblocks.c b/block/badblocks.c
index 6ebcef282314..43c71166e1e2 100644
--- a/block/badblocks.c
+++ b/block/badblocks.c
@@ -533,6 +533,7 @@ ssize_t badblocks_store(struct badblocks *bb, const char *page, size_t len,
 	case 3:
 		if (newline != '\n')
 			return -EINVAL;
+		/* fall through */
 	case 2:
 		if (length <= 0)
 			return -EINVAL;
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index ed93da2462ab..12bbc6b8657d 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -725,8 +725,12 @@ static void bfq_updated_next_req(struct bfq_data *bfqd,
 }
 
 static void
-bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_io_cq *bic)
+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 = bfqq->wr_coeff;
+	bool busy = bfq_already_existing && bfq_bfqq_busy(bfqq);
+
 	if (bic->saved_idle_window)
 		bfq_mark_bfqq_idle_window(bfqq);
 	else
@@ -754,6 +758,14 @@ bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_io_cq *bic)
 
 	/* 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++;
+	else if (old_wr_coeff > 1 && bfqq->wr_coeff == 1)
+		bfqd->wr_busy_queues--;
 }
 
 static int bfqq_process_refs(struct bfq_queue *bfqq)
@@ -4290,10 +4302,16 @@ 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 = RQ_BFQQ(rq);
-	struct bfq_data *bfqd = bfqq->bfqd;
+	struct bfq_queue *bfqq;
+	struct bfq_data *bfqd;
+
+	if (!rq->elv.icq)
+		return;
+
+	bfqq = RQ_BFQQ(rq);
+	bfqd = bfqq->bfqd;
 
 	if (rq->rq_flags & RQF_STARTED)
 		bfqg_stats_update_completion(bfqq_group(bfqq),
@@ -4324,7 +4342,7 @@ static void bfq_put_rq_private(struct request_queue *q, struct request *rq)
 		 */
 
 		if (!RB_EMPTY_NODE(&rq->rb_node))
-			bfq_remove_request(q, rq);
+			bfq_remove_request(rq->q, rq);
 		bfq_put_rq_priv_body(bfqq);
 	}
 
@@ -4394,20 +4412,21 @@ 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 = icq_to_bic(rq->elv.icq);
+	struct bfq_io_cq *bic;
 	const int is_sync = rq_is_sync(rq);
 	struct bfq_queue *bfqq;
 	bool new_queue = false;
-	bool split = false;
+	bool bfqq_already_existing = false, split = false;
 
-	spin_lock_irq(&bfqd->lock);
+	if (!rq->elv.icq)
+		return;
+	bic = icq_to_bic(rq->elv.icq);
 
-	if (!bic)
-		goto queue_fail;
+	spin_lock_irq(&bfqd->lock);
 
 	bfq_check_ioprio_change(bic, bio);
 
@@ -4432,6 +4451,8 @@ static int bfq_get_rq_private(struct request_queue *q, struct request *rq,
 				bfqq = bfq_get_bfqq_handle_split(bfqd, bic, bio,
 								 true, is_sync,
 								 NULL);
+			else
+				bfqq_already_existing = true;
 		}
 	}
 
@@ -4457,7 +4478,8 @@ static int bfq_get_rq_private(struct request_queue *q, struct request *rq,
 			 * queue: restore the idle window and the
 			 * possible weight raising period.
 			 */
-			bfq_bfqq_resume_state(bfqq, bic);
+			bfq_bfqq_resume_state(bfqq, bfqd, bic,
+					      bfqq_already_existing);
 		}
 	}
 
@@ -4465,13 +4487,6 @@ static int bfq_get_rq_private(struct request_queue *q, struct request *rq,
 		bfq_handle_burst(bfqd, bfqq);
 
 	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)
@@ -4950,8 +4965,8 @@ 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,
+		.prepare_request	= bfq_prepare_request,
+		.finish_request		= bfq_finish_request,
 		.exit_icq		= bfq_exit_icq,
 		.insert_requests	= bfq_insert_requests,
 		.dispatch_request	= bfq_dispatch_request,
diff --git a/block/bio-integrity.c b/block/bio-integrity.c
index b5009a896a7f..b8a3a65f7364 100644
--- a/block/bio-integrity.c
+++ b/block/bio-integrity.c
@@ -224,7 +224,7 @@ static inline unsigned int bio_integrity_bytes(struct blk_integrity *bi,
  * @bio:	bio to generate/verify integrity metadata for
  * @proc_fn:	Pointer to the relevant processing function
  */
-static int bio_integrity_process(struct bio *bio,
+static blk_status_t bio_integrity_process(struct bio *bio,
 				 integrity_processing_fn *proc_fn)
 {
 	struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);
@@ -232,7 +232,7 @@ static int bio_integrity_process(struct bio *bio,
 	struct bvec_iter bviter;
 	struct bio_vec bv;
 	struct bio_integrity_payload *bip = bio_integrity(bio);
-	unsigned int ret = 0;
+	blk_status_t ret = BLK_STS_OK;
 	void *prot_buf = page_address(bip->bip_vec->bv_page) +
 		bip->bip_vec->bv_offset;
 
@@ -369,7 +369,7 @@ static void bio_integrity_verify_fn(struct work_struct *work)
 	struct bio *bio = bip->bip_bio;
 	struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);
 
-	bio->bi_error = bio_integrity_process(bio, bi->profile->verify_fn);
+	bio->bi_status = bio_integrity_process(bio, bi->profile->verify_fn);
 
 	/* Restore original bio completion handler */
 	bio->bi_end_io = bip->bip_end_io;
@@ -398,7 +398,7 @@ void bio_integrity_endio(struct bio *bio)
 	 * integrity metadata.  Restore original bio end_io handler
 	 * and run it.
 	 */
-	if (bio->bi_error) {
+	if (bio->bi_status) {
 		bio->bi_end_io = bip->bip_end_io;
 		bio_endio(bio);
 
diff --git a/block/bio.c b/block/bio.c
index 26b0810fb8ea..1cfcd0df3f30 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -315,8 +315,8 @@ static struct bio *__bio_chain_endio(struct bio *bio)
 {
 	struct bio *parent = bio->bi_private;
 
-	if (!parent->bi_error)
-		parent->bi_error = bio->bi_error;
+	if (!parent->bi_status)
+		parent->bi_status = bio->bi_status;
 	bio_put(bio);
 	return parent;
 }
@@ -369,6 +369,8 @@ static void punt_bios_to_rescuer(struct bio_set *bs)
 	struct bio_list punt, nopunt;
 	struct bio *bio;
 
+	if (WARN_ON_ONCE(!bs->rescue_workqueue))
+		return;
 	/*
 	 * In order to guarantee forward progress we must punt only bios that
 	 * were allocated from this bio_set; otherwise, if there was a bio on
@@ -480,7 +482,8 @@ struct bio *bio_alloc_bioset(gfp_t gfp_mask, unsigned int nr_iovecs,
 
 		if (current->bio_list &&
 		    (!bio_list_empty(&current->bio_list[0]) ||
-		     !bio_list_empty(&current->bio_list[1])))
+		     !bio_list_empty(&current->bio_list[1])) &&
+		    bs->rescue_workqueue)
 			gfp_mask &= ~__GFP_DIRECT_RECLAIM;
 
 		p = mempool_alloc(bs->bio_pool, gfp_mask);
@@ -550,7 +553,7 @@ EXPORT_SYMBOL(zero_fill_bio);
  *
  * Description:
  *   Put a reference to a &struct bio, either one you have gotten with
- *   bio_alloc, bio_get or bio_clone. The last put of a bio will free it.
+ *   bio_alloc, bio_get or bio_clone_*. The last put of a bio will free it.
  **/
 void bio_put(struct bio *bio)
 {
@@ -599,6 +602,7 @@ void __bio_clone_fast(struct bio *bio, struct bio *bio_src)
 	bio->bi_bdev = bio_src->bi_bdev;
 	bio_set_flag(bio, BIO_CLONED);
 	bio->bi_opf = bio_src->bi_opf;
+	bio->bi_write_hint = bio_src->bi_write_hint;
 	bio->bi_iter = bio_src->bi_iter;
 	bio->bi_io_vec = bio_src->bi_io_vec;
 
@@ -682,6 +686,7 @@ struct bio *bio_clone_bioset(struct bio *bio_src, gfp_t gfp_mask,
 		return NULL;
 	bio->bi_bdev		= bio_src->bi_bdev;
 	bio->bi_opf		= bio_src->bi_opf;
+	bio->bi_write_hint	= bio_src->bi_write_hint;
 	bio->bi_iter.bi_sector	= bio_src->bi_iter.bi_sector;
 	bio->bi_iter.bi_size	= bio_src->bi_iter.bi_size;
 
@@ -924,7 +929,7 @@ static void submit_bio_wait_endio(struct bio *bio)
 {
 	struct submit_bio_ret *ret = bio->bi_private;
 
-	ret->error = bio->bi_error;
+	ret->error = blk_status_to_errno(bio->bi_status);
 	complete(&ret->event);
 }
 
@@ -1823,8 +1828,8 @@ again:
 	}
 
 	if (bio->bi_bdev && bio_flagged(bio, BIO_TRACE_COMPLETION)) {
-		trace_block_bio_complete(bdev_get_queue(bio->bi_bdev),
-					 bio, bio->bi_error);
+		trace_block_bio_complete(bdev_get_queue(bio->bi_bdev), bio,
+					 blk_status_to_errno(bio->bi_status));
 		bio_clear_flag(bio, BIO_TRACE_COMPLETION);
 	}
 
@@ -1927,9 +1932,29 @@ void bioset_free(struct bio_set *bs)
 }
 EXPORT_SYMBOL(bioset_free);
 
-static struct bio_set *__bioset_create(unsigned int pool_size,
-				       unsigned int front_pad,
-				       bool create_bvec_pool)
+/**
+ * bioset_create  - Create a bio_set
+ * @pool_size:	Number of bio and bio_vecs to cache in the mempool
+ * @front_pad:	Number of bytes to allocate in front of the returned bio
+ * @flags:	Flags to modify behavior, currently %BIOSET_NEED_BVECS
+ *              and %BIOSET_NEED_RESCUER
+ *
+ * Description:
+ *    Set up a bio_set to be used with @bio_alloc_bioset. Allows the caller
+ *    to ask for a number of bytes to be allocated in front of the bio.
+ *    Front pad allocation is useful for embedding the bio inside
+ *    another structure, to avoid allocating extra data to go with the bio.
+ *    Note that the bio must be embedded at the END of that structure always,
+ *    or things will break badly.
+ *    If %BIOSET_NEED_BVECS is set in @flags, a separate pool will be allocated
+ *    for allocating iovecs.  This pool is not needed e.g. for bio_clone_fast().
+ *    If %BIOSET_NEED_RESCUER is set, a workqueue is created which can be used to
+ *    dispatch queued requests when the mempool runs out of space.
+ *
+ */
+struct bio_set *bioset_create(unsigned int pool_size,
+			      unsigned int front_pad,
+			      int flags)
 {
 	unsigned int back_pad = BIO_INLINE_VECS * sizeof(struct bio_vec);
 	struct bio_set *bs;
@@ -1954,12 +1979,15 @@ static struct bio_set *__bioset_create(unsigned int pool_size,
 	if (!bs->bio_pool)
 		goto bad;
 
-	if (create_bvec_pool) {
+	if (flags & BIOSET_NEED_BVECS) {
 		bs->bvec_pool = biovec_create_pool(pool_size);
 		if (!bs->bvec_pool)
 			goto bad;
 	}
 
+	if (!(flags & BIOSET_NEED_RESCUER))
+		return bs;
+
 	bs->rescue_workqueue = alloc_workqueue("bioset", WQ_MEM_RECLAIM, 0);
 	if (!bs->rescue_workqueue)
 		goto bad;
@@ -1969,41 +1997,8 @@ bad:
 	bioset_free(bs);
 	return NULL;
 }
-
-/**
- * bioset_create  - Create a bio_set
- * @pool_size:	Number of bio and bio_vecs to cache in the mempool
- * @front_pad:	Number of bytes to allocate in front of the returned bio
- *
- * Description:
- *    Set up a bio_set to be used with @bio_alloc_bioset. Allows the caller
- *    to ask for a number of bytes to be allocated in front of the bio.
- *    Front pad allocation is useful for embedding the bio inside
- *    another structure, to avoid allocating extra data to go with the bio.
- *    Note that the bio must be embedded at the END of that structure always,
- *    or things will break badly.
- */
-struct bio_set *bioset_create(unsigned int pool_size, unsigned int front_pad)
-{
-	return __bioset_create(pool_size, front_pad, true);
-}
 EXPORT_SYMBOL(bioset_create);
 
-/**
- * bioset_create_nobvec  - Create a bio_set without bio_vec mempool
- * @pool_size:	Number of bio to cache in the mempool
- * @front_pad:	Number of bytes to allocate in front of the returned bio
- *
- * Description:
- *    Same functionality as bioset_create() except that mempool is not
- *    created for bio_vecs. Saving some memory for bio_clone_fast() users.
- */
-struct bio_set *bioset_create_nobvec(unsigned int pool_size, unsigned int front_pad)
-{
-	return __bioset_create(pool_size, front_pad, false);
-}
-EXPORT_SYMBOL(bioset_create_nobvec);
-
 #ifdef CONFIG_BLK_CGROUP
 
 /**
@@ -2118,7 +2113,7 @@ static int __init init_bio(void)
 	bio_integrity_init();
 	biovec_init_slabs();
 
-	fs_bio_set = bioset_create(BIO_POOL_SIZE, 0);
+	fs_bio_set = bioset_create(BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
 	if (!fs_bio_set)
 		panic("bio: can't allocate bios\n");
 
diff --git a/block/blk-core.c b/block/blk-core.c
index a7421b772d0e..af393d5a9680 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -129,11 +129,70 @@ void blk_rq_init(struct request_queue *q, struct request *rq)
 }
 EXPORT_SYMBOL(blk_rq_init);
 
+static const struct {
+	int		errno;
+	const char	*name;
+} blk_errors[] = {
+	[BLK_STS_OK]		= { 0,		"" },
+	[BLK_STS_NOTSUPP]	= { -EOPNOTSUPP, "operation not supported" },
+	[BLK_STS_TIMEOUT]	= { -ETIMEDOUT,	"timeout" },
+	[BLK_STS_NOSPC]		= { -ENOSPC,	"critical space allocation" },
+	[BLK_STS_TRANSPORT]	= { -ENOLINK,	"recoverable transport" },
+	[BLK_STS_TARGET]	= { -EREMOTEIO,	"critical target" },
+	[BLK_STS_NEXUS]		= { -EBADE,	"critical nexus" },
+	[BLK_STS_MEDIUM]	= { -ENODATA,	"critical medium" },
+	[BLK_STS_PROTECTION]	= { -EILSEQ,	"protection" },
+	[BLK_STS_RESOURCE]	= { -ENOMEM,	"kernel resource" },
+	[BLK_STS_AGAIN]		= { -EAGAIN,	"nonblocking retry" },
+
+	/* device mapper special case, should not leak out: */
+	[BLK_STS_DM_REQUEUE]	= { -EREMCHG, "dm internal retry" },
+
+	/* everything else not covered above: */
+	[BLK_STS_IOERR]		= { -EIO,	"I/O" },
+};
+
+blk_status_t errno_to_blk_status(int errno)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(blk_errors); i++) {
+		if (blk_errors[i].errno == errno)
+			return (__force blk_status_t)i;
+	}
+
+	return BLK_STS_IOERR;
+}
+EXPORT_SYMBOL_GPL(errno_to_blk_status);
+
+int blk_status_to_errno(blk_status_t status)
+{
+	int idx = (__force int)status;
+
+	if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors)))
+		return -EIO;
+	return blk_errors[idx].errno;
+}
+EXPORT_SYMBOL_GPL(blk_status_to_errno);
+
+static void print_req_error(struct request *req, blk_status_t status)
+{
+	int idx = (__force int)status;
+
+	if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors)))
+		return;
+
+	printk_ratelimited(KERN_ERR "%s: %s error, dev %s, sector %llu\n",
+			   __func__, blk_errors[idx].name, req->rq_disk ?
+			   req->rq_disk->disk_name : "?",
+			   (unsigned long long)blk_rq_pos(req));
+}
+
 static void req_bio_endio(struct request *rq, struct bio *bio,
-			  unsigned int nbytes, int error)
+			  unsigned int nbytes, blk_status_t error)
 {
 	if (error)
-		bio->bi_error = error;
+		bio->bi_status = error;
 
 	if (unlikely(rq->rq_flags & RQF_QUIET))
 		bio_set_flag(bio, BIO_QUIET);
@@ -177,10 +236,13 @@ static void blk_delay_work(struct work_struct *work)
  * Description:
  *   Sometimes queueing needs to be postponed for a little while, to allow
  *   resources to come back. This function will make sure that queueing is
- *   restarted around the specified time. Queue lock must be held.
+ *   restarted around the specified time.
  */
 void blk_delay_queue(struct request_queue *q, unsigned long msecs)
 {
+	lockdep_assert_held(q->queue_lock);
+	WARN_ON_ONCE(q->mq_ops);
+
 	if (likely(!blk_queue_dead(q)))
 		queue_delayed_work(kblockd_workqueue, &q->delay_work,
 				   msecs_to_jiffies(msecs));
@@ -198,6 +260,9 @@ EXPORT_SYMBOL(blk_delay_queue);
  **/
 void blk_start_queue_async(struct request_queue *q)
 {
+	lockdep_assert_held(q->queue_lock);
+	WARN_ON_ONCE(q->mq_ops);
+
 	queue_flag_clear(QUEUE_FLAG_STOPPED, q);
 	blk_run_queue_async(q);
 }
@@ -210,11 +275,13 @@ EXPORT_SYMBOL(blk_start_queue_async);
  * Description:
  *   blk_start_queue() will clear the stop flag on the queue, and call
  *   the request_fn for the queue if it was in a stopped state when
- *   entered. Also see blk_stop_queue(). Queue lock must be held.
+ *   entered. Also see blk_stop_queue().
  **/
 void blk_start_queue(struct request_queue *q)
 {
+	lockdep_assert_held(q->queue_lock);
 	WARN_ON(!irqs_disabled());
+	WARN_ON_ONCE(q->mq_ops);
 
 	queue_flag_clear(QUEUE_FLAG_STOPPED, q);
 	__blk_run_queue(q);
@@ -233,10 +300,13 @@ EXPORT_SYMBOL(blk_start_queue);
  *   or if it simply chooses not to queue more I/O at one point, it can
  *   call this function to prevent the request_fn from being called until
  *   the driver has signalled it's ready to go again. This happens by calling
- *   blk_start_queue() to restart queue operations. Queue lock must be held.
+ *   blk_start_queue() to restart queue operations.
  **/
 void blk_stop_queue(struct request_queue *q)
 {
+	lockdep_assert_held(q->queue_lock);
+	WARN_ON_ONCE(q->mq_ops);
+
 	cancel_delayed_work(&q->delay_work);
 	queue_flag_set(QUEUE_FLAG_STOPPED, q);
 }
@@ -289,6 +359,9 @@ EXPORT_SYMBOL(blk_sync_queue);
  */
 inline void __blk_run_queue_uncond(struct request_queue *q)
 {
+	lockdep_assert_held(q->queue_lock);
+	WARN_ON_ONCE(q->mq_ops);
+
 	if (unlikely(blk_queue_dead(q)))
 		return;
 
@@ -310,11 +383,13 @@ EXPORT_SYMBOL_GPL(__blk_run_queue_uncond);
  * @q:	The queue to run
  *
  * Description:
- *    See @blk_run_queue. This variant must be called with the queue lock
- *    held and interrupts disabled.
+ *    See @blk_run_queue.
  */
 void __blk_run_queue(struct request_queue *q)
 {
+	lockdep_assert_held(q->queue_lock);
+	WARN_ON_ONCE(q->mq_ops);
+
 	if (unlikely(blk_queue_stopped(q)))
 		return;
 
@@ -328,10 +403,18 @@ EXPORT_SYMBOL(__blk_run_queue);
  *
  * Description:
  *    Tells kblockd to perform the equivalent of @blk_run_queue on behalf
- *    of us. The caller must hold the queue lock.
+ *    of us.
+ *
+ * Note:
+ *    Since it is not allowed to run q->delay_work after blk_cleanup_queue()
+ *    has canceled q->delay_work, callers must hold the queue lock to avoid
+ *    race conditions between blk_cleanup_queue() and blk_run_queue_async().
  */
 void blk_run_queue_async(struct request_queue *q)
 {
+	lockdep_assert_held(q->queue_lock);
+	WARN_ON_ONCE(q->mq_ops);
+
 	if (likely(!blk_queue_stopped(q) && !blk_queue_dead(q)))
 		mod_delayed_work(kblockd_workqueue, &q->delay_work, 0);
 }
@@ -349,6 +432,8 @@ void blk_run_queue(struct request_queue *q)
 {
 	unsigned long flags;
 
+	WARN_ON_ONCE(q->mq_ops);
+
 	spin_lock_irqsave(q->queue_lock, flags);
 	__blk_run_queue(q);
 	spin_unlock_irqrestore(q->queue_lock, flags);
@@ -377,6 +462,7 @@ static void __blk_drain_queue(struct request_queue *q, bool drain_all)
 	int i;
 
 	lockdep_assert_held(q->queue_lock);
+	WARN_ON_ONCE(q->mq_ops);
 
 	while (true) {
 		bool drain = false;
@@ -455,6 +541,8 @@ static void __blk_drain_queue(struct request_queue *q, bool drain_all)
  */
 void blk_queue_bypass_start(struct request_queue *q)
 {
+	WARN_ON_ONCE(q->mq_ops);
+
 	spin_lock_irq(q->queue_lock);
 	q->bypass_depth++;
 	queue_flag_set(QUEUE_FLAG_BYPASS, q);
@@ -481,6 +569,9 @@ EXPORT_SYMBOL_GPL(blk_queue_bypass_start);
  * @q: queue of interest
  *
  * Leave bypass mode and restore the normal queueing behavior.
+ *
+ * Note: although blk_queue_bypass_start() is only called for blk-sq queues,
+ * this function is called for both blk-sq and blk-mq queues.
  */
 void blk_queue_bypass_end(struct request_queue *q)
 {
@@ -732,7 +823,7 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
 	if (q->id < 0)
 		goto fail_q;
 
-	q->bio_split = bioset_create(BIO_POOL_SIZE, 0);
+	q->bio_split = bioset_create(BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
 	if (!q->bio_split)
 		goto fail_id;
 
@@ -878,6 +969,8 @@ static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio);
 
 int blk_init_allocated_queue(struct request_queue *q)
 {
+	WARN_ON_ONCE(q->mq_ops);
+
 	q->fq = blk_alloc_flush_queue(q, NUMA_NO_NODE, q->cmd_size);
 	if (!q->fq)
 		return -ENOMEM;
@@ -1015,6 +1108,8 @@ int blk_update_nr_requests(struct request_queue *q, unsigned int nr)
 	struct request_list *rl;
 	int on_thresh, off_thresh;
 
+	WARN_ON_ONCE(q->mq_ops);
+
 	spin_lock_irq(q->queue_lock);
 	q->nr_requests = nr;
 	blk_queue_congestion_threshold(q);
@@ -1077,6 +1172,8 @@ static struct request *__get_request(struct request_list *rl, unsigned int op,
 	int may_queue;
 	req_flags_t rq_flags = RQF_ALLOCED;
 
+	lockdep_assert_held(q->queue_lock);
+
 	if (unlikely(blk_queue_dying(q)))
 		return ERR_PTR(-ENODEV);
 
@@ -1250,12 +1347,20 @@ static struct request *get_request(struct request_queue *q, unsigned int op,
 	struct request_list *rl;
 	struct request *rq;
 
+	lockdep_assert_held(q->queue_lock);
+	WARN_ON_ONCE(q->mq_ops);
+
 	rl = blk_get_rl(q, bio);	/* transferred to @rq on success */
 retry:
 	rq = __get_request(rl, op, bio, gfp_mask);
 	if (!IS_ERR(rq))
 		return rq;
 
+	if (op & REQ_NOWAIT) {
+		blk_put_rl(rl);
+		return ERR_PTR(-EAGAIN);
+	}
+
 	if (!gfpflags_allow_blocking(gfp_mask) || unlikely(blk_queue_dying(q))) {
 		blk_put_rl(rl);
 		return rq;
@@ -1283,16 +1388,18 @@ retry:
 	goto retry;
 }
 
-static struct request *blk_old_get_request(struct request_queue *q, int rw,
-		gfp_t gfp_mask)
+static struct request *blk_old_get_request(struct request_queue *q,
+					   unsigned int op, gfp_t gfp_mask)
 {
 	struct request *rq;
 
+	WARN_ON_ONCE(q->mq_ops);
+
 	/* create ioc upfront */
 	create_io_context(gfp_mask, q->node);
 
 	spin_lock_irq(q->queue_lock);
-	rq = get_request(q, rw, NULL, gfp_mask);
+	rq = get_request(q, op, NULL, gfp_mask);
 	if (IS_ERR(rq)) {
 		spin_unlock_irq(q->queue_lock);
 		return rq;
@@ -1305,14 +1412,24 @@ static struct request *blk_old_get_request(struct request_queue *q, int rw,
 	return rq;
 }
 
-struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask)
+struct request *blk_get_request(struct request_queue *q, unsigned int op,
+				gfp_t gfp_mask)
 {
-	if (q->mq_ops)
-		return blk_mq_alloc_request(q, rw,
+	struct request *req;
+
+	if (q->mq_ops) {
+		req = blk_mq_alloc_request(q, op,
 			(gfp_mask & __GFP_DIRECT_RECLAIM) ?
 				0 : BLK_MQ_REQ_NOWAIT);
-	else
-		return blk_old_get_request(q, rw, gfp_mask);
+		if (!IS_ERR(req) && q->mq_ops->initialize_rq_fn)
+			q->mq_ops->initialize_rq_fn(req);
+	} else {
+		req = blk_old_get_request(q, op, gfp_mask);
+		if (!IS_ERR(req) && q->initialize_rq_fn)
+			q->initialize_rq_fn(req);
+	}
+
+	return req;
 }
 EXPORT_SYMBOL(blk_get_request);
 
@@ -1328,6 +1445,9 @@ EXPORT_SYMBOL(blk_get_request);
  */
 void blk_requeue_request(struct request_queue *q, struct request *rq)
 {
+	lockdep_assert_held(q->queue_lock);
+	WARN_ON_ONCE(q->mq_ops);
+
 	blk_delete_timer(rq);
 	blk_clear_rq_complete(rq);
 	trace_block_rq_requeue(q, rq);
@@ -1402,9 +1522,6 @@ static void blk_pm_put_request(struct request *rq)
 static inline void blk_pm_put_request(struct request *rq) {}
 #endif
 
-/*
- * queue lock must be held
- */
 void __blk_put_request(struct request_queue *q, struct request *req)
 {
 	req_flags_t rq_flags = req->rq_flags;
@@ -1417,6 +1534,8 @@ void __blk_put_request(struct request_queue *q, struct request *req)
 		return;
 	}
 
+	lockdep_assert_held(q->queue_lock);
+
 	blk_pm_put_request(req);
 
 	elv_completed_request(q, req);
@@ -1646,6 +1765,7 @@ void blk_init_request_from_bio(struct request *req, struct bio *bio)
 		req->ioprio = ioc->ioprio;
 	else
 		req->ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0);
+	req->write_hint = bio->bi_write_hint;
 	blk_rq_bio_prep(req->q, req, bio);
 }
 EXPORT_SYMBOL_GPL(blk_init_request_from_bio);
@@ -1665,10 +1785,10 @@ static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio)
 	 */
 	blk_queue_bounce(q, &bio);
 
-	blk_queue_split(q, &bio, q->bio_split);
+	blk_queue_split(q, &bio);
 
 	if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
-		bio->bi_error = -EIO;
+		bio->bi_status = BLK_STS_IOERR;
 		bio_endio(bio);
 		return BLK_QC_T_NONE;
 	}
@@ -1726,7 +1846,10 @@ get_rq:
 	req = get_request(q, bio->bi_opf, bio, GFP_NOIO);
 	if (IS_ERR(req)) {
 		__wbt_done(q->rq_wb, wb_acct);
-		bio->bi_error = PTR_ERR(req);
+		if (PTR_ERR(req) == -ENOMEM)
+			bio->bi_status = BLK_STS_RESOURCE;
+		else
+			bio->bi_status = BLK_STS_IOERR;
 		bio_endio(bio);
 		goto out_unlock;
 	}
@@ -1881,7 +2004,7 @@ generic_make_request_checks(struct bio *bio)
 {
 	struct request_queue *q;
 	int nr_sectors = bio_sectors(bio);
-	int err = -EIO;
+	blk_status_t status = BLK_STS_IOERR;
 	char b[BDEVNAME_SIZE];
 	struct hd_struct *part;
 
@@ -1900,6 +2023,14 @@ generic_make_request_checks(struct bio *bio)
 		goto end_io;
 	}
 
+	/*
+	 * For a REQ_NOWAIT based request, return -EOPNOTSUPP
+	 * if queue is not a request based queue.
+	 */
+
+	if ((bio->bi_opf & REQ_NOWAIT) && !queue_is_rq_based(q))
+		goto not_supported;
+
 	part = bio->bi_bdev->bd_part;
 	if (should_fail_request(part, bio->bi_iter.bi_size) ||
 	    should_fail_request(&part_to_disk(part)->part0,
@@ -1924,7 +2055,7 @@ generic_make_request_checks(struct bio *bio)
 	    !test_bit(QUEUE_FLAG_WC, &q->queue_flags)) {
 		bio->bi_opf &= ~(REQ_PREFLUSH | REQ_FUA);
 		if (!nr_sectors) {
-			err = 0;
+			status = BLK_STS_OK;
 			goto end_io;
 		}
 	}
@@ -1976,9 +2107,9 @@ generic_make_request_checks(struct bio *bio)
 	return true;
 
 not_supported:
-	err = -EOPNOTSUPP;
+	status = BLK_STS_NOTSUPP;
 end_io:
-	bio->bi_error = err;
+	bio->bi_status = status;
 	bio_endio(bio);
 	return false;
 }
@@ -2057,7 +2188,7 @@ blk_qc_t generic_make_request(struct bio *bio)
 	do {
 		struct request_queue *q = bdev_get_queue(bio->bi_bdev);
 
-		if (likely(blk_queue_enter(q, false) == 0)) {
+		if (likely(blk_queue_enter(q, bio->bi_opf & REQ_NOWAIT) == 0)) {
 			struct bio_list lower, same;
 
 			/* Create a fresh bio_list for all subordinate requests */
@@ -2082,7 +2213,11 @@ blk_qc_t generic_make_request(struct bio *bio)
 			bio_list_merge(&bio_list_on_stack[0], &same);
 			bio_list_merge(&bio_list_on_stack[0], &bio_list_on_stack[1]);
 		} else {
-			bio_io_error(bio);
+			if (unlikely(!blk_queue_dying(q) &&
+					(bio->bi_opf & REQ_NOWAIT)))
+				bio_wouldblock_error(bio);
+			else
+				bio_io_error(bio);
 		}
 		bio = bio_list_pop(&bio_list_on_stack[0]);
 	} while (bio);
@@ -2183,29 +2318,29 @@ static int blk_cloned_rq_check_limits(struct request_queue *q,
  * @q:  the queue to submit the request
  * @rq: the request being queued
  */
-int blk_insert_cloned_request(struct request_queue *q, struct request *rq)
+blk_status_t blk_insert_cloned_request(struct request_queue *q, struct request *rq)
 {
 	unsigned long flags;
 	int where = ELEVATOR_INSERT_BACK;
 
 	if (blk_cloned_rq_check_limits(q, rq))
-		return -EIO;
+		return BLK_STS_IOERR;
 
 	if (rq->rq_disk &&
 	    should_fail_request(&rq->rq_disk->part0, blk_rq_bytes(rq)))
-		return -EIO;
+		return BLK_STS_IOERR;
 
 	if (q->mq_ops) {
 		if (blk_queue_io_stat(q))
 			blk_account_io_start(rq, true);
 		blk_mq_sched_insert_request(rq, false, true, false, false);
-		return 0;
+		return BLK_STS_OK;
 	}
 
 	spin_lock_irqsave(q->queue_lock, flags);
 	if (unlikely(blk_queue_dying(q))) {
 		spin_unlock_irqrestore(q->queue_lock, flags);
-		return -ENODEV;
+		return BLK_STS_IOERR;
 	}
 
 	/*
@@ -2222,7 +2357,7 @@ int blk_insert_cloned_request(struct request_queue *q, struct request *rq)
 		__blk_run_queue(q);
 	spin_unlock_irqrestore(q->queue_lock, flags);
 
-	return 0;
+	return BLK_STS_OK;
 }
 EXPORT_SYMBOL_GPL(blk_insert_cloned_request);
 
@@ -2238,9 +2373,6 @@ EXPORT_SYMBOL_GPL(blk_insert_cloned_request);
  *
  * Return:
  *     The number of bytes to fail.
- *
- * Context:
- *     queue_lock must be held.
  */
 unsigned int blk_rq_err_bytes(const struct request *rq)
 {
@@ -2380,15 +2512,15 @@ void blk_account_io_start(struct request *rq, bool new_io)
  * Return:
  *     Pointer to the request at the top of @q if available.  Null
  *     otherwise.
- *
- * Context:
- *     queue_lock must be held.
  */
 struct request *blk_peek_request(struct request_queue *q)
 {
 	struct request *rq;
 	int ret;
 
+	lockdep_assert_held(q->queue_lock);
+	WARN_ON_ONCE(q->mq_ops);
+
 	while ((rq = __elv_next_request(q)) != NULL) {
 
 		rq = blk_pm_peek_request(q, rq);
@@ -2456,15 +2588,14 @@ struct request *blk_peek_request(struct request_queue *q)
 			rq = NULL;
 			break;
 		} else if (ret == BLKPREP_KILL || ret == BLKPREP_INVALID) {
-			int err = (ret == BLKPREP_INVALID) ? -EREMOTEIO : -EIO;
-
 			rq->rq_flags |= RQF_QUIET;
 			/*
 			 * Mark this request as started so we don't trigger
 			 * any debug logic in the end I/O path.
 			 */
 			blk_start_request(rq);
-			__blk_end_request_all(rq, err);
+			__blk_end_request_all(rq, ret == BLKPREP_INVALID ?
+					BLK_STS_TARGET : BLK_STS_IOERR);
 		} else {
 			printk(KERN_ERR "%s: bad return=%d\n", __func__, ret);
 			break;
@@ -2505,12 +2636,12 @@ void blk_dequeue_request(struct request *rq)
  *
  *     Block internal functions which don't want to start timer should
  *     call blk_dequeue_request().
- *
- * Context:
- *     queue_lock must be held.
  */
 void blk_start_request(struct request *req)
 {
+	lockdep_assert_held(req->q->queue_lock);
+	WARN_ON_ONCE(req->q->mq_ops);
+
 	blk_dequeue_request(req);
 
 	if (test_bit(QUEUE_FLAG_STATS, &req->q->queue_flags)) {
@@ -2535,14 +2666,14 @@ EXPORT_SYMBOL(blk_start_request);
  * Return:
  *     Pointer to the request at the top of @q if available.  Null
  *     otherwise.
- *
- * Context:
- *     queue_lock must be held.
  */
 struct request *blk_fetch_request(struct request_queue *q)
 {
 	struct request *rq;
 
+	lockdep_assert_held(q->queue_lock);
+	WARN_ON_ONCE(q->mq_ops);
+
 	rq = blk_peek_request(q);
 	if (rq)
 		blk_start_request(rq);
@@ -2553,7 +2684,7 @@ EXPORT_SYMBOL(blk_fetch_request);
 /**
  * blk_update_request - Special helper function for request stacking drivers
  * @req:      the request being processed
- * @error:    %0 for success, < %0 for error
+ * @error:    block status code
  * @nr_bytes: number of bytes to complete @req
  *
  * Description:
@@ -2572,49 +2703,19 @@ EXPORT_SYMBOL(blk_fetch_request);
  *     %false - this request doesn't have any more data
  *     %true  - this request has more data
  **/
-bool blk_update_request(struct request *req, int error, unsigned int nr_bytes)
+bool blk_update_request(struct request *req, blk_status_t error,
+		unsigned int nr_bytes)
 {
 	int total_bytes;
 
-	trace_block_rq_complete(req, error, nr_bytes);
+	trace_block_rq_complete(req, blk_status_to_errno(error), nr_bytes);
 
 	if (!req->bio)
 		return false;
 
-	if (error && !blk_rq_is_passthrough(req) &&
-	    !(req->rq_flags & RQF_QUIET)) {
-		char *error_type;
-
-		switch (error) {
-		case -ENOLINK:
-			error_type = "recoverable transport";
-			break;
-		case -EREMOTEIO:
-			error_type = "critical target";
-			break;
-		case -EBADE:
-			error_type = "critical nexus";
-			break;
-		case -ETIMEDOUT:
-			error_type = "timeout";
-			break;
-		case -ENOSPC:
-			error_type = "critical space allocation";
-			break;
-		case -ENODATA:
-			error_type = "critical medium";
-			break;
-		case -EIO:
-		default:
-			error_type = "I/O";
-			break;
-		}
-		printk_ratelimited(KERN_ERR "%s: %s error, dev %s, sector %llu\n",
-				   __func__, error_type, req->rq_disk ?
-				   req->rq_disk->disk_name : "?",
-				   (unsigned long long)blk_rq_pos(req));
-
-	}
+	if (unlikely(error && !blk_rq_is_passthrough(req) &&
+		     !(req->rq_flags & RQF_QUIET)))
+		print_req_error(req, error);
 
 	blk_account_io_completion(req, nr_bytes);
 
@@ -2680,7 +2781,7 @@ bool blk_update_request(struct request *req, int error, unsigned int nr_bytes)
 }
 EXPORT_SYMBOL_GPL(blk_update_request);
 
-static bool blk_update_bidi_request(struct request *rq, int error,
+static bool blk_update_bidi_request(struct request *rq, blk_status_t error,
 				    unsigned int nr_bytes,
 				    unsigned int bidi_bytes)
 {
@@ -2718,13 +2819,13 @@ void blk_unprep_request(struct request *req)
 }
 EXPORT_SYMBOL_GPL(blk_unprep_request);
 
-/*
- * queue lock must be held
- */
-void blk_finish_request(struct request *req, int error)
+void blk_finish_request(struct request *req, blk_status_t error)
 {
 	struct request_queue *q = req->q;
 
+	lockdep_assert_held(req->q->queue_lock);
+	WARN_ON_ONCE(q->mq_ops);
+
 	if (req->rq_flags & RQF_STATS)
 		blk_stat_add(req);
 
@@ -2758,7 +2859,7 @@ EXPORT_SYMBOL(blk_finish_request);
 /**
  * blk_end_bidi_request - Complete a bidi request
  * @rq:         the request to complete
- * @error:      %0 for success, < %0 for error
+ * @error:      block status code
  * @nr_bytes:   number of bytes to complete @rq
  * @bidi_bytes: number of bytes to complete @rq->next_rq
  *
@@ -2772,12 +2873,14 @@ EXPORT_SYMBOL(blk_finish_request);
  *     %false - we are done with this request
  *     %true  - still buffers pending for this request
  **/
-static bool blk_end_bidi_request(struct request *rq, int error,
+static bool blk_end_bidi_request(struct request *rq, blk_status_t error,
 				 unsigned int nr_bytes, unsigned int bidi_bytes)
 {
 	struct request_queue *q = rq->q;
 	unsigned long flags;
 
+	WARN_ON_ONCE(q->mq_ops);
+
 	if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes))
 		return true;
 
@@ -2791,7 +2894,7 @@ static bool blk_end_bidi_request(struct request *rq, int error,
 /**
  * __blk_end_bidi_request - Complete a bidi request with queue lock held
  * @rq:         the request to complete
- * @error:      %0 for success, < %0 for error
+ * @error:      block status code
  * @nr_bytes:   number of bytes to complete @rq
  * @bidi_bytes: number of bytes to complete @rq->next_rq
  *
@@ -2803,9 +2906,12 @@ static bool blk_end_bidi_request(struct request *rq, int error,
  *     %false - we are done with this request
  *     %true  - still buffers pending for this request
  **/
-static bool __blk_end_bidi_request(struct request *rq, int error,
+static bool __blk_end_bidi_request(struct request *rq, blk_status_t error,
 				   unsigned int nr_bytes, unsigned int bidi_bytes)
 {
+	lockdep_assert_held(rq->q->queue_lock);
+	WARN_ON_ONCE(rq->q->mq_ops);
+
 	if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes))
 		return true;
 
@@ -2817,7 +2923,7 @@ static bool __blk_end_bidi_request(struct request *rq, int error,
 /**
  * blk_end_request - Helper function for drivers to complete the request.
  * @rq:       the request being processed
- * @error:    %0 for success, < %0 for error
+ * @error:    block status code
  * @nr_bytes: number of bytes to complete
  *
  * Description:
@@ -2828,8 +2934,10 @@ static bool __blk_end_bidi_request(struct request *rq, int error,
  *     %false - we are done with this request
  *     %true  - still buffers pending for this request
  **/
-bool blk_end_request(struct request *rq, int error, unsigned int nr_bytes)
+bool blk_end_request(struct request *rq, blk_status_t error,
+		unsigned int nr_bytes)
 {
+	WARN_ON_ONCE(rq->q->mq_ops);
 	return blk_end_bidi_request(rq, error, nr_bytes, 0);
 }
 EXPORT_SYMBOL(blk_end_request);
@@ -2837,12 +2945,12 @@ EXPORT_SYMBOL(blk_end_request);
 /**
  * blk_end_request_all - Helper function for drives to finish the request.
  * @rq: the request to finish
- * @error: %0 for success, < %0 for error
+ * @error: block status code
  *
  * Description:
  *     Completely finish @rq.
  */
-void blk_end_request_all(struct request *rq, int error)
+void blk_end_request_all(struct request *rq, blk_status_t error)
 {
 	bool pending;
 	unsigned int bidi_bytes = 0;
@@ -2858,7 +2966,7 @@ EXPORT_SYMBOL(blk_end_request_all);
 /**
  * __blk_end_request - Helper function for drivers to complete the request.
  * @rq:       the request being processed
- * @error:    %0 for success, < %0 for error
+ * @error:    block status code
  * @nr_bytes: number of bytes to complete
  *
  * Description:
@@ -2868,8 +2976,12 @@ EXPORT_SYMBOL(blk_end_request_all);
  *     %false - we are done with this request
  *     %true  - still buffers pending for this request
  **/
-bool __blk_end_request(struct request *rq, int error, unsigned int nr_bytes)
+bool __blk_end_request(struct request *rq, blk_status_t error,
+		unsigned int nr_bytes)
 {
+	lockdep_assert_held(rq->q->queue_lock);
+	WARN_ON_ONCE(rq->q->mq_ops);
+
 	return __blk_end_bidi_request(rq, error, nr_bytes, 0);
 }
 EXPORT_SYMBOL(__blk_end_request);
@@ -2877,16 +2989,19 @@ EXPORT_SYMBOL(__blk_end_request);
 /**
  * __blk_end_request_all - Helper function for drives to finish the request.
  * @rq: the request to finish
- * @error: %0 for success, < %0 for error
+ * @error:    block status code
  *
  * Description:
  *     Completely finish @rq.  Must be called with queue lock held.
  */
-void __blk_end_request_all(struct request *rq, int error)
+void __blk_end_request_all(struct request *rq, blk_status_t error)
 {
 	bool pending;
 	unsigned int bidi_bytes = 0;
 
+	lockdep_assert_held(rq->q->queue_lock);
+	WARN_ON_ONCE(rq->q->mq_ops);
+
 	if (unlikely(blk_bidi_rq(rq)))
 		bidi_bytes = blk_rq_bytes(rq->next_rq);
 
@@ -2898,7 +3013,7 @@ EXPORT_SYMBOL(__blk_end_request_all);
 /**
  * __blk_end_request_cur - Helper function to finish the current request chunk.
  * @rq: the request to finish the current chunk for
- * @error: %0 for success, < %0 for error
+ * @error:    block status code
  *
  * Description:
  *     Complete the current consecutively mapped chunk from @rq.  Must
@@ -2908,7 +3023,7 @@ EXPORT_SYMBOL(__blk_end_request_all);
  *     %false - we are done with this request
  *     %true  - still buffers pending for this request
  */
-bool __blk_end_request_cur(struct request *rq, int error)
+bool __blk_end_request_cur(struct request *rq, blk_status_t error)
 {
 	return __blk_end_request(rq, error, blk_rq_cur_bytes(rq));
 }
@@ -3151,6 +3266,8 @@ static void queue_unplugged(struct request_queue *q, unsigned int depth,
 			    bool from_schedule)
 	__releases(q->queue_lock)
 {
+	lockdep_assert_held(q->queue_lock);
+
 	trace_block_unplug(q, depth, !from_schedule);
 
 	if (from_schedule)
@@ -3249,7 +3366,7 @@ void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule)
 		 * Short-circuit if @q is dead
 		 */
 		if (unlikely(blk_queue_dying(q))) {
-			__blk_end_request_all(rq, -ENODEV);
+			__blk_end_request_all(rq, BLK_STS_IOERR);
 			continue;
 		}
 
diff --git a/block/blk-exec.c b/block/blk-exec.c
index a9451e3b8587..5c0f3dc446dc 100644
--- a/block/blk-exec.c
+++ b/block/blk-exec.c
@@ -16,7 +16,7 @@
  * @rq: request to complete
  * @error: end I/O status of the request
  */
-static void blk_end_sync_rq(struct request *rq, int error)
+static void blk_end_sync_rq(struct request *rq, blk_status_t error)
 {
 	struct completion *waiting = rq->end_io_data;
 
@@ -69,7 +69,7 @@ void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk,
 
 	if (unlikely(blk_queue_dying(q))) {
 		rq->rq_flags |= RQF_QUIET;
-		__blk_end_request_all(rq, -ENXIO);
+		__blk_end_request_all(rq, BLK_STS_IOERR);
 		spin_unlock_irq(q->queue_lock);
 		return;
 	}
diff --git a/block/blk-flush.c b/block/blk-flush.c
index c4e0880b54bb..ed5fe322abba 100644
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -164,7 +164,7 @@ static bool blk_flush_queue_rq(struct request *rq, bool add_front)
  */
 static bool blk_flush_complete_seq(struct request *rq,
 				   struct blk_flush_queue *fq,
-				   unsigned int seq, int error)
+				   unsigned int seq, blk_status_t error)
 {
 	struct request_queue *q = rq->q;
 	struct list_head *pending = &fq->flush_queue[fq->flush_pending_idx];
@@ -216,7 +216,7 @@ static bool blk_flush_complete_seq(struct request *rq,
 	return kicked | queued;
 }
 
-static void flush_end_io(struct request *flush_rq, int error)
+static void flush_end_io(struct request *flush_rq, blk_status_t error)
 {
 	struct request_queue *q = flush_rq->q;
 	struct list_head *running;
@@ -341,11 +341,13 @@ static bool blk_kick_flush(struct request_queue *q, struct blk_flush_queue *fq)
 	return blk_flush_queue_rq(flush_rq, false);
 }
 
-static void flush_data_end_io(struct request *rq, int error)
+static void flush_data_end_io(struct request *rq, blk_status_t error)
 {
 	struct request_queue *q = rq->q;
 	struct blk_flush_queue *fq = blk_get_flush_queue(q, NULL);
 
+	lockdep_assert_held(q->queue_lock);
+
 	/*
 	 * Updating q->in_flight[] here for making this tag usable
 	 * early. Because in blk_queue_start_tag(),
@@ -382,7 +384,7 @@ static void flush_data_end_io(struct request *rq, int error)
 		blk_run_queue_async(q);
 }
 
-static void mq_flush_data_end_io(struct request *rq, int error)
+static void mq_flush_data_end_io(struct request *rq, blk_status_t error)
 {
 	struct request_queue *q = rq->q;
 	struct blk_mq_hw_ctx *hctx;
@@ -411,9 +413,6 @@ static void mq_flush_data_end_io(struct request *rq, int error)
  * or __blk_mq_run_hw_queue() to dispatch request.
  * @rq is being submitted.  Analyze what needs to be done and put it on the
  * right queue.
- *
- * CONTEXT:
- * spin_lock_irq(q->queue_lock) in !mq case
  */
 void blk_insert_flush(struct request *rq)
 {
@@ -422,6 +421,9 @@ void blk_insert_flush(struct request *rq)
 	unsigned int policy = blk_flush_policy(fflags, rq);
 	struct blk_flush_queue *fq = blk_get_flush_queue(q, rq->mq_ctx);
 
+	if (!q->mq_ops)
+		lockdep_assert_held(q->queue_lock);
+
 	/*
 	 * @policy now records what operations need to be done.  Adjust
 	 * REQ_PREFLUSH and FUA for the driver.
diff --git a/block/blk-integrity.c b/block/blk-integrity.c
index 0f891a9aff4d..feb30570eaf5 100644
--- a/block/blk-integrity.c
+++ b/block/blk-integrity.c
@@ -384,9 +384,9 @@ static struct kobj_type integrity_ktype = {
 	.sysfs_ops	= &integrity_ops,
 };
 
-static int blk_integrity_nop_fn(struct blk_integrity_iter *iter)
+static blk_status_t blk_integrity_nop_fn(struct blk_integrity_iter *iter)
 {
-	return 0;
+	return BLK_STS_OK;
 }
 
 static const struct blk_integrity_profile nop_profile = {
diff --git a/block/blk-map.c b/block/blk-map.c
index 3b5cb863318f..2547016aa7aa 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -16,6 +16,8 @@
  */
 int blk_rq_append_bio(struct request *rq, struct bio *bio)
 {
+	blk_queue_bounce(rq->q, &bio);
+
 	if (!rq->bio) {
 		blk_rq_bio_prep(rq->q, rq, bio);
 	} else {
@@ -72,15 +74,13 @@ static int __blk_rq_map_user_iov(struct request *rq,
 		map_data->offset += bio->bi_iter.bi_size;
 
 	orig_bio = bio;
-	blk_queue_bounce(q, &bio);
 
 	/*
 	 * We link the bounce buffer in and could have to traverse it
 	 * later so we have to get a ref to prevent it from being freed
 	 */
-	bio_get(bio);
-
 	ret = blk_rq_append_bio(rq, bio);
+	bio_get(bio);
 	if (ret) {
 		bio_endio(bio);
 		__blk_rq_unmap_user(orig_bio);
@@ -249,7 +249,6 @@ int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
 		return ret;
 	}
 
-	blk_queue_bounce(q, &rq->bio);
 	return 0;
 }
 EXPORT_SYMBOL(blk_rq_map_kern);
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 3990ae406341..99038830fb42 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -108,31 +108,9 @@ static struct bio *blk_bio_segment_split(struct request_queue *q,
 	bool do_split = true;
 	struct bio *new = NULL;
 	const unsigned max_sectors = get_max_io_size(q, bio);
-	unsigned bvecs = 0;
 
 	bio_for_each_segment(bv, bio, iter) {
 		/*
-		 * With arbitrary bio size, the incoming bio may be very
-		 * big. We have to split the bio into small bios so that
-		 * each holds at most BIO_MAX_PAGES bvecs because
-		 * bio_clone() can fail to allocate big bvecs.
-		 *
-		 * It should have been better to apply the limit per
-		 * request queue in which bio_clone() is involved,
-		 * instead of globally. The biggest blocker is the
-		 * bio_clone() in bio bounce.
-		 *
-		 * If bio is splitted by this reason, we should have
-		 * allowed to continue bios merging, but don't do
-		 * that now for making the change simple.
-		 *
-		 * TODO: deal with bio bounce's bio_clone() gracefully
-		 * and convert the global limit into per-queue limit.
-		 */
-		if (bvecs++ >= BIO_MAX_PAGES)
-			goto split;
-
-		/*
 		 * If the queue doesn't support SG gaps and adding this
 		 * offset would create a gap, disallow it.
 		 */
@@ -202,8 +180,7 @@ split:
 	return do_split ? new : NULL;
 }
 
-void blk_queue_split(struct request_queue *q, struct bio **bio,
-		     struct bio_set *bs)
+void blk_queue_split(struct request_queue *q, struct bio **bio)
 {
 	struct bio *split, *res;
 	unsigned nsegs;
@@ -211,13 +188,13 @@ void blk_queue_split(struct request_queue *q, struct bio **bio,
 	switch (bio_op(*bio)) {
 	case REQ_OP_DISCARD:
 	case REQ_OP_SECURE_ERASE:
-		split = blk_bio_discard_split(q, *bio, bs, &nsegs);
+		split = blk_bio_discard_split(q, *bio, q->bio_split, &nsegs);
 		break;
 	case REQ_OP_WRITE_ZEROES:
-		split = blk_bio_write_zeroes_split(q, *bio, bs, &nsegs);
+		split = blk_bio_write_zeroes_split(q, *bio, q->bio_split, &nsegs);
 		break;
 	case REQ_OP_WRITE_SAME:
-		split = blk_bio_write_same_split(q, *bio, bs, &nsegs);
+		split = blk_bio_write_same_split(q, *bio, q->bio_split, &nsegs);
 		break;
 	default:
 		split = blk_bio_segment_split(q, *bio, q->bio_split, &nsegs);
@@ -671,6 +648,9 @@ static void blk_account_io_merge(struct request *req)
 static struct request *attempt_merge(struct request_queue *q,
 				     struct request *req, struct request *next)
 {
+	if (!q->mq_ops)
+		lockdep_assert_held(q->queue_lock);
+
 	if (!rq_mergeable(req) || !rq_mergeable(next))
 		return NULL;
 
@@ -693,6 +673,13 @@ static struct request *attempt_merge(struct request_queue *q,
 		return NULL;
 
 	/*
+	 * Don't allow merge of different write hints, or for a hint with
+	 * non-hint IO.
+	 */
+	if (req->write_hint != next->write_hint)
+		return NULL;
+
+	/*
 	 * If we are allowed to merge, then append bio list
 	 * from next to rq and release next. merge_requests_fn
 	 * will have updated segment counts, update sector
@@ -811,6 +798,13 @@ bool blk_rq_merge_ok(struct request *rq, struct bio *bio)
 	    !blk_write_same_mergeable(rq->bio, bio))
 		return false;
 
+	/*
+	 * Don't allow merge of different write hints, or for a hint with
+	 * non-hint IO.
+	 */
+	if (rq->write_hint != bio->bi_write_hint)
+		return false;
+
 	return true;
 }
 
diff --git a/block/blk-mq-cpumap.c b/block/blk-mq-cpumap.c
index 8e61e8640e17..2cca4fc43f45 100644
--- a/block/blk-mq-cpumap.c
+++ b/block/blk-mq-cpumap.c
@@ -14,10 +14,15 @@
 #include "blk.h"
 #include "blk-mq.h"
 
-static int cpu_to_queue_index(unsigned int nr_cpus, unsigned int nr_queues,
-			      const int cpu)
+static int cpu_to_queue_index(unsigned int nr_queues, const int cpu,
+			      const struct cpumask *online_mask)
 {
-	return cpu * nr_queues / nr_cpus;
+	/*
+	 * Non online CPU will be mapped to queue index 0.
+	 */
+	if (!cpumask_test_cpu(cpu, online_mask))
+		return 0;
+	return cpu % nr_queues;
 }
 
 static int get_first_sibling(unsigned int cpu)
@@ -36,55 +41,26 @@ int blk_mq_map_queues(struct blk_mq_tag_set *set)
 	unsigned int *map = set->mq_map;
 	unsigned int nr_queues = set->nr_hw_queues;
 	const struct cpumask *online_mask = cpu_online_mask;
-	unsigned int i, nr_cpus, nr_uniq_cpus, queue, first_sibling;
-	cpumask_var_t cpus;
-
-	if (!alloc_cpumask_var(&cpus, GFP_ATOMIC))
-		return -ENOMEM;
-
-	cpumask_clear(cpus);
-	nr_cpus = nr_uniq_cpus = 0;
-	for_each_cpu(i, online_mask) {
-		nr_cpus++;
-		first_sibling = get_first_sibling(i);
-		if (!cpumask_test_cpu(first_sibling, cpus))
-			nr_uniq_cpus++;
-		cpumask_set_cpu(i, cpus);
-	}
-
-	queue = 0;
-	for_each_possible_cpu(i) {
-		if (!cpumask_test_cpu(i, online_mask)) {
-			map[i] = 0;
-			continue;
-		}
+	unsigned int cpu, first_sibling;
 
+	for_each_possible_cpu(cpu) {
 		/*
-		 * Easy case - we have equal or more hardware queues. Or
-		 * there are no thread siblings to take into account. Do
-		 * 1:1 if enough, or sequential mapping if less.
+		 * 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.
 		 */
-		if (nr_queues >= nr_cpus || nr_cpus == nr_uniq_cpus) {
-			map[i] = cpu_to_queue_index(nr_cpus, nr_queues, queue);
-			queue++;
-			continue;
+		if (cpu < nr_queues) {
+			map[cpu] = cpu_to_queue_index(nr_queues, cpu, online_mask);
+		} else {
+			first_sibling = get_first_sibling(cpu);
+			if (first_sibling == cpu)
+				map[cpu] = cpu_to_queue_index(nr_queues, cpu, online_mask);
+			else
+				map[cpu] = map[first_sibling];
 		}
-
-		/*
-		 * Less then nr_cpus queues, and we have some number of
-		 * threads per cores. Map sibling threads to the same
-		 * queue.
-		 */
-		first_sibling = get_first_sibling(i);
-		if (first_sibling == i) {
-			map[i] = cpu_to_queue_index(nr_uniq_cpus, nr_queues,
-							queue);
-			queue++;
-		} else
-			map[i] = map[first_sibling];
 	}
 
-	free_cpumask_var(cpus);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(blk_mq_map_queues);
diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 803aed4d7221..9ebc2945f991 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -114,10 +114,12 @@ static ssize_t queue_state_write(void *data, const char __user *buf,
 		blk_mq_run_hw_queues(q, true);
 	} else if (strcmp(op, "start") == 0) {
 		blk_mq_start_stopped_hw_queues(q, true);
+	} else if (strcmp(op, "kick") == 0) {
+		blk_mq_kick_requeue_list(q);
 	} else {
 		pr_err("%s: unsupported operation '%s'\n", __func__, op);
 inval:
-		pr_err("%s: use either 'run' or 'start'\n", __func__);
+		pr_err("%s: use 'run', 'start' or 'kick'\n", __func__);
 		return -EINVAL;
 	}
 	return count;
@@ -133,6 +135,29 @@ static void print_stat(struct seq_file *m, struct blk_rq_stat *stat)
 	}
 }
 
+static int queue_write_hint_show(void *data, struct seq_file *m)
+{
+	struct request_queue *q = data;
+	int i;
+
+	for (i = 0; i < BLK_MAX_WRITE_HINTS; i++)
+		seq_printf(m, "hint%d: %llu\n", i, q->write_hints[i]);
+
+	return 0;
+}
+
+static ssize_t queue_write_hint_store(void *data, const char __user *buf,
+				      size_t count, loff_t *ppos)
+{
+	struct request_queue *q = data;
+	int i;
+
+	for (i = 0; i < BLK_MAX_WRITE_HINTS; i++)
+		q->write_hints[i] = 0;
+
+	return count;
+}
+
 static int queue_poll_stat_show(void *data, struct seq_file *m)
 {
 	struct request_queue *q = data;
@@ -267,6 +292,14 @@ static const char *const rqf_name[] = {
 };
 #undef RQF_NAME
 
+#define RQAF_NAME(name) [REQ_ATOM_##name] = #name
+static const char *const rqaf_name[] = {
+	RQAF_NAME(COMPLETE),
+	RQAF_NAME(STARTED),
+	RQAF_NAME(POLL_SLEPT),
+};
+#undef RQAF_NAME
+
 int __blk_mq_debugfs_rq_show(struct seq_file *m, struct request *rq)
 {
 	const struct blk_mq_ops *const mq_ops = rq->q->mq_ops;
@@ -283,6 +316,8 @@ int __blk_mq_debugfs_rq_show(struct seq_file *m, struct request *rq)
 	seq_puts(m, ", .rq_flags=");
 	blk_flags_show(m, (__force unsigned int)rq->rq_flags, rqf_name,
 		       ARRAY_SIZE(rqf_name));
+	seq_puts(m, ", .atomic_flags=");
+	blk_flags_show(m, rq->atomic_flags, rqaf_name, ARRAY_SIZE(rqaf_name));
 	seq_printf(m, ", .tag=%d, .internal_tag=%d", rq->tag,
 		   rq->internal_tag);
 	if (mq_ops->show_rq)
@@ -298,6 +333,37 @@ int blk_mq_debugfs_rq_show(struct seq_file *m, void *v)
 }
 EXPORT_SYMBOL_GPL(blk_mq_debugfs_rq_show);
 
+static void *queue_requeue_list_start(struct seq_file *m, loff_t *pos)
+	__acquires(&q->requeue_lock)
+{
+	struct request_queue *q = m->private;
+
+	spin_lock_irq(&q->requeue_lock);
+	return seq_list_start(&q->requeue_list, *pos);
+}
+
+static void *queue_requeue_list_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	struct request_queue *q = m->private;
+
+	return seq_list_next(v, &q->requeue_list, pos);
+}
+
+static void queue_requeue_list_stop(struct seq_file *m, void *v)
+	__releases(&q->requeue_lock)
+{
+	struct request_queue *q = m->private;
+
+	spin_unlock_irq(&q->requeue_lock);
+}
+
+static const struct seq_operations queue_requeue_list_seq_ops = {
+	.start	= queue_requeue_list_start,
+	.next	= queue_requeue_list_next,
+	.stop	= queue_requeue_list_stop,
+	.show	= blk_mq_debugfs_rq_show,
+};
+
 static void *hctx_dispatch_start(struct seq_file *m, loff_t *pos)
 	__acquires(&hctx->lock)
 {
@@ -329,6 +395,36 @@ static const struct seq_operations hctx_dispatch_seq_ops = {
 	.show	= blk_mq_debugfs_rq_show,
 };
 
+struct show_busy_params {
+	struct seq_file		*m;
+	struct blk_mq_hw_ctx	*hctx;
+};
+
+/*
+ * Note: the state of a request may change while this function is in progress,
+ * e.g. due to a concurrent blk_mq_finish_request() call.
+ */
+static void hctx_show_busy_rq(struct request *rq, void *data, bool reserved)
+{
+	const struct show_busy_params *params = data;
+
+	if (blk_mq_map_queue(rq->q, rq->mq_ctx->cpu) == params->hctx &&
+	    test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
+		__blk_mq_debugfs_rq_show(params->m,
+					 list_entry_rq(&rq->queuelist));
+}
+
+static int hctx_busy_show(void *data, struct seq_file *m)
+{
+	struct blk_mq_hw_ctx *hctx = data;
+	struct show_busy_params params = { .m = m, .hctx = hctx };
+
+	blk_mq_tagset_busy_iter(hctx->queue->tag_set, hctx_show_busy_rq,
+				&params);
+
+	return 0;
+}
+
 static int hctx_ctx_map_show(void *data, struct seq_file *m)
 {
 	struct blk_mq_hw_ctx *hctx = data;
@@ -655,7 +751,9 @@ const struct file_operations blk_mq_debugfs_fops = {
 
 static const struct blk_mq_debugfs_attr blk_mq_debugfs_queue_attrs[] = {
 	{"poll_stat", 0400, queue_poll_stat_show},
+	{"requeue_list", 0400, .seq_ops = &queue_requeue_list_seq_ops},
 	{"state", 0600, queue_state_show, queue_state_write},
+	{"write_hints", 0600, queue_write_hint_show, queue_write_hint_store},
 	{},
 };
 
@@ -663,6 +761,7 @@ static const struct blk_mq_debugfs_attr blk_mq_debugfs_hctx_attrs[] = {
 	{"state", 0400, hctx_state_show},
 	{"flags", 0400, hctx_flags_show},
 	{"dispatch", 0400, .seq_ops = &hctx_dispatch_seq_ops},
+	{"busy", 0400, hctx_busy_show},
 	{"ctx_map", 0400, hctx_ctx_map_show},
 	{"tags", 0400, hctx_tags_show},
 	{"tags_bitmap", 0400, hctx_tags_bitmap_show},
diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index 0ded5e846335..7f0dc48ffb40 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -31,11 +31,10 @@ void blk_mq_sched_free_hctx_data(struct request_queue *q,
 }
 EXPORT_SYMBOL_GPL(blk_mq_sched_free_hctx_data);
 
-static void __blk_mq_sched_assign_ioc(struct request_queue *q,
-				      struct request *rq,
-				      struct bio *bio,
-				      struct io_context *ioc)
+void blk_mq_sched_assign_ioc(struct request *rq, struct bio *bio)
 {
+	struct request_queue *q = rq->q;
+	struct io_context *ioc = rq_ioc(bio);
 	struct io_cq *icq;
 
 	spin_lock_irq(q->queue_lock);
@@ -47,25 +46,8 @@ static void __blk_mq_sched_assign_ioc(struct request_queue *q,
 		if (!icq)
 			return;
 	}
-
+	get_io_context(icq->ioc);
 	rq->elv.icq = icq;
-	if (!blk_mq_sched_get_rq_priv(q, rq, bio)) {
-		rq->rq_flags |= RQF_ELVPRIV;
-		get_io_context(icq->ioc);
-		return;
-	}
-
-	rq->elv.icq = NULL;
-}
-
-static void blk_mq_sched_assign_ioc(struct request_queue *q,
-				    struct request *rq, struct bio *bio)
-{
-	struct io_context *ioc;
-
-	ioc = rq_ioc(bio);
-	if (ioc)
-		__blk_mq_sched_assign_ioc(q, rq, bio, ioc);
 }
 
 /*
@@ -107,71 +89,6 @@ static bool blk_mq_sched_restart_hctx(struct blk_mq_hw_ctx *hctx)
 	return false;
 }
 
-struct request *blk_mq_sched_get_request(struct request_queue *q,
-					 struct bio *bio,
-					 unsigned int op,
-					 struct blk_mq_alloc_data *data)
-{
-	struct elevator_queue *e = q->elevator;
-	struct request *rq;
-
-	blk_queue_enter_live(q);
-	data->q = q;
-	if (likely(!data->ctx))
-		data->ctx = blk_mq_get_ctx(q);
-	if (likely(!data->hctx))
-		data->hctx = blk_mq_map_queue(q, data->ctx->cpu);
-
-	if (e) {
-		data->flags |= BLK_MQ_REQ_INTERNAL;
-
-		/*
-		 * Flush requests are special and go directly to the
-		 * dispatch list.
-		 */
-		if (!op_is_flush(op) && e->type->ops.mq.get_request) {
-			rq = e->type->ops.mq.get_request(q, op, data);
-			if (rq)
-				rq->rq_flags |= RQF_QUEUED;
-		} else
-			rq = __blk_mq_alloc_request(data, op);
-	} else {
-		rq = __blk_mq_alloc_request(data, op);
-	}
-
-	if (rq) {
-		if (!op_is_flush(op)) {
-			rq->elv.icq = NULL;
-			if (e && e->type->icq_cache)
-				blk_mq_sched_assign_ioc(q, rq, bio);
-		}
-		data->hctx->queued++;
-		return rq;
-	}
-
-	blk_queue_exit(q);
-	return NULL;
-}
-
-void blk_mq_sched_put_request(struct request *rq)
-{
-	struct request_queue *q = rq->q;
-	struct elevator_queue *e = q->elevator;
-
-	if (rq->rq_flags & RQF_ELVPRIV) {
-		blk_mq_sched_put_rq_priv(rq->q, rq);
-		if (rq->elv.icq) {
-			put_io_context(rq->elv.icq->ioc);
-			rq->elv.icq = NULL;
-		}
-	}
-
-	if ((rq->rq_flags & RQF_QUEUED) && e && e->type->ops.mq.put_request)
-		e->type->ops.mq.put_request(rq);
-	else
-		blk_mq_finish_request(rq);
-}
-
 void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
 {
 	struct request_queue *q = hctx->queue;
@@ -180,7 +97,8 @@ void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
 	bool did_work = false;
 	LIST_HEAD(rq_list);
 
-	if (unlikely(blk_mq_hctx_stopped(hctx)))
+	/* RCU or SRCU read lock is needed before checking quiesced flag */
+	if (unlikely(blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q)))
 		return;
 
 	hctx->run++;
@@ -260,19 +178,73 @@ bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio,
 }
 EXPORT_SYMBOL_GPL(blk_mq_sched_try_merge);
 
+/*
+ * Reverse check our software queue for entries that we could potentially
+ * merge with. Currently includes a hand-wavy stop count of 8, to not spend
+ * too much time checking for merges.
+ */
+static bool blk_mq_attempt_merge(struct request_queue *q,
+				 struct blk_mq_ctx *ctx, struct bio *bio)
+{
+	struct request *rq;
+	int checked = 8;
+
+	lockdep_assert_held(&ctx->lock);
+
+	list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) {
+		bool merged = false;
+
+		if (!checked--)
+			break;
+
+		if (!blk_rq_merge_ok(rq, bio))
+			continue;
+
+		switch (blk_try_merge(rq, bio)) {
+		case ELEVATOR_BACK_MERGE:
+			if (blk_mq_sched_allow_merge(q, rq, bio))
+				merged = bio_attempt_back_merge(q, rq, bio);
+			break;
+		case ELEVATOR_FRONT_MERGE:
+			if (blk_mq_sched_allow_merge(q, rq, bio))
+				merged = bio_attempt_front_merge(q, rq, bio);
+			break;
+		case ELEVATOR_DISCARD_MERGE:
+			merged = bio_attempt_discard_merge(q, rq, bio);
+			break;
+		default:
+			continue;
+		}
+
+		if (merged)
+			ctx->rq_merged++;
+		return merged;
+	}
+
+	return false;
+}
+
 bool __blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio)
 {
 	struct elevator_queue *e = q->elevator;
+	struct blk_mq_ctx *ctx = blk_mq_get_ctx(q);
+	struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
+	bool ret = false;
 
-	if (e->type->ops.mq.bio_merge) {
-		struct blk_mq_ctx *ctx = blk_mq_get_ctx(q);
-		struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
-
+	if (e && e->type->ops.mq.bio_merge) {
 		blk_mq_put_ctx(ctx);
 		return e->type->ops.mq.bio_merge(hctx, bio);
 	}
 
-	return false;
+	if (hctx->flags & BLK_MQ_F_SHOULD_MERGE) {
+		/* default per sw-queue merge */
+		spin_lock(&ctx->lock);
+		ret = blk_mq_attempt_merge(q, ctx, bio);
+		spin_unlock(&ctx->lock);
+	}
+
+	blk_mq_put_ctx(ctx);
+	return ret;
 }
 
 bool blk_mq_sched_try_insert_merge(struct request_queue *q, struct request *rq)
diff --git a/block/blk-mq-sched.h b/block/blk-mq-sched.h
index 5007edece51a..9267d0b7c197 100644
--- a/block/blk-mq-sched.h
+++ b/block/blk-mq-sched.h
@@ -7,8 +7,7 @@
 void blk_mq_sched_free_hctx_data(struct request_queue *q,
 				 void (*exit)(struct blk_mq_hw_ctx *));
 
-struct request *blk_mq_sched_get_request(struct request_queue *q, struct bio *bio, unsigned int op, struct blk_mq_alloc_data *data);
-void blk_mq_sched_put_request(struct request *rq);
+void blk_mq_sched_assign_ioc(struct request *rq, struct bio *bio);
 
 void blk_mq_sched_request_inserted(struct request *rq);
 bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio,
@@ -38,35 +37,12 @@ int blk_mq_sched_init(struct request_queue *q);
 static inline bool
 blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio)
 {
-	struct elevator_queue *e = q->elevator;
-
-	if (!e || blk_queue_nomerges(q) || !bio_mergeable(bio))
+	if (blk_queue_nomerges(q) || !bio_mergeable(bio))
 		return false;
 
 	return __blk_mq_sched_bio_merge(q, bio);
 }
 
-static inline int blk_mq_sched_get_rq_priv(struct request_queue *q,
-					   struct request *rq,
-					   struct bio *bio)
-{
-	struct elevator_queue *e = q->elevator;
-
-	if (e && e->type->ops.mq.get_rq_priv)
-		return e->type->ops.mq.get_rq_priv(q, rq, bio);
-
-	return 0;
-}
-
-static inline void blk_mq_sched_put_rq_priv(struct request_queue *q,
-					    struct request *rq)
-{
-	struct elevator_queue *e = q->elevator;
-
-	if (e && e->type->ops.mq.put_rq_priv)
-		e->type->ops.mq.put_rq_priv(q, rq);
-}
-
 static inline bool
 blk_mq_sched_allow_merge(struct request_queue *q, struct request *rq,
 			 struct bio *bio)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 958cedaff8b8..05dfa3f270ae 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -42,7 +42,6 @@ static LIST_HEAD(all_q_list);
 
 static void blk_mq_poll_stats_start(struct request_queue *q);
 static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb);
-static void __blk_mq_stop_hw_queues(struct request_queue *q, bool sync);
 
 static int blk_mq_poll_stats_bkt(const struct request *rq)
 {
@@ -154,13 +153,28 @@ void blk_mq_unfreeze_queue(struct request_queue *q)
 }
 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue);
 
+/*
+ * FIXME: replace the scsi_internal_device_*block_nowait() calls in the
+ * mpt3sas driver such that this function can be removed.
+ */
+void blk_mq_quiesce_queue_nowait(struct request_queue *q)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(q->queue_lock, flags);
+	queue_flag_set(QUEUE_FLAG_QUIESCED, q);
+	spin_unlock_irqrestore(q->queue_lock, flags);
+}
+EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait);
+
 /**
- * blk_mq_quiesce_queue() - wait until all ongoing queue_rq calls have finished
+ * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished
  * @q: request queue.
  *
  * Note: this function does not prevent that the struct request end_io()
- * callback function is invoked. Additionally, it is not prevented that
- * new queue_rq() calls occur unless the queue has been stopped first.
+ * callback function is invoked. Once this function is returned, we make
+ * sure no dispatch can happen until the queue is unquiesced via
+ * blk_mq_unquiesce_queue().
  */
 void blk_mq_quiesce_queue(struct request_queue *q)
 {
@@ -168,11 +182,11 @@ void blk_mq_quiesce_queue(struct request_queue *q)
 	unsigned int i;
 	bool rcu = false;
 
-	__blk_mq_stop_hw_queues(q, true);
+	blk_mq_quiesce_queue_nowait(q);
 
 	queue_for_each_hw_ctx(q, hctx, i) {
 		if (hctx->flags & BLK_MQ_F_BLOCKING)
-			synchronize_srcu(&hctx->queue_rq_srcu);
+			synchronize_srcu(hctx->queue_rq_srcu);
 		else
 			rcu = true;
 	}
@@ -181,6 +195,26 @@ void blk_mq_quiesce_queue(struct request_queue *q)
 }
 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue);
 
+/*
+ * blk_mq_unquiesce_queue() - counterpart of blk_mq_quiesce_queue()
+ * @q: request queue.
+ *
+ * This function recovers queue into the state before quiescing
+ * which is done by blk_mq_quiesce_queue.
+ */
+void blk_mq_unquiesce_queue(struct request_queue *q)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(q->queue_lock, flags);
+	queue_flag_clear(QUEUE_FLAG_QUIESCED, q);
+	spin_unlock_irqrestore(q->queue_lock, flags);
+
+	/* dispatch requests which are inserted during quiescing */
+	blk_mq_run_hw_queues(q, true);
+}
+EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue);
+
 void blk_mq_wake_waiters(struct request_queue *q)
 {
 	struct blk_mq_hw_ctx *hctx;
@@ -204,15 +238,33 @@ bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx)
 }
 EXPORT_SYMBOL(blk_mq_can_queue);
 
-void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx,
-			struct request *rq, unsigned int op)
+static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
+		unsigned int tag, unsigned int op)
 {
+	struct blk_mq_tags *tags = blk_mq_tags_from_data(data);
+	struct request *rq = tags->static_rqs[tag];
+
+	rq->rq_flags = 0;
+
+	if (data->flags & BLK_MQ_REQ_INTERNAL) {
+		rq->tag = -1;
+		rq->internal_tag = tag;
+	} else {
+		if (blk_mq_tag_busy(data->hctx)) {
+			rq->rq_flags = RQF_MQ_INFLIGHT;
+			atomic_inc(&data->hctx->nr_active);
+		}
+		rq->tag = tag;
+		rq->internal_tag = -1;
+		data->hctx->tags->rqs[rq->tag] = rq;
+	}
+
 	INIT_LIST_HEAD(&rq->queuelist);
 	/* csd/requeue_work/fifo_time is initialized before use */
-	rq->q = q;
-	rq->mq_ctx = ctx;
+	rq->q = data->q;
+	rq->mq_ctx = data->ctx;
 	rq->cmd_flags = op;
-	if (blk_queue_io_stat(q))
+	if (blk_queue_io_stat(data->q))
 		rq->rq_flags |= RQF_IO_STAT;
 	/* do not touch atomic flags, it needs atomic ops against the timer */
 	rq->cpu = -1;
@@ -241,44 +293,60 @@ void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx,
 	rq->end_io_data = NULL;
 	rq->next_rq = NULL;
 
-	ctx->rq_dispatched[op_is_sync(op)]++;
+	data->ctx->rq_dispatched[op_is_sync(op)]++;
+	return rq;
 }
-EXPORT_SYMBOL_GPL(blk_mq_rq_ctx_init);
 
-struct request *__blk_mq_alloc_request(struct blk_mq_alloc_data *data,
-				       unsigned int op)
+static struct request *blk_mq_get_request(struct request_queue *q,
+		struct bio *bio, unsigned int op,
+		struct blk_mq_alloc_data *data)
 {
+	struct elevator_queue *e = q->elevator;
 	struct request *rq;
 	unsigned int tag;
 
-	tag = blk_mq_get_tag(data);
-	if (tag != BLK_MQ_TAG_FAIL) {
-		struct blk_mq_tags *tags = blk_mq_tags_from_data(data);
+	blk_queue_enter_live(q);
+	data->q = q;
+	if (likely(!data->ctx))
+		data->ctx = blk_mq_get_ctx(q);
+	if (likely(!data->hctx))
+		data->hctx = blk_mq_map_queue(q, data->ctx->cpu);
+	if (op & REQ_NOWAIT)
+		data->flags |= BLK_MQ_REQ_NOWAIT;
 
-		rq = tags->static_rqs[tag];
+	if (e) {
+		data->flags |= BLK_MQ_REQ_INTERNAL;
 
-		if (data->flags & BLK_MQ_REQ_INTERNAL) {
-			rq->tag = -1;
-			rq->internal_tag = tag;
-		} else {
-			if (blk_mq_tag_busy(data->hctx)) {
-				rq->rq_flags = RQF_MQ_INFLIGHT;
-				atomic_inc(&data->hctx->nr_active);
-			}
-			rq->tag = tag;
-			rq->internal_tag = -1;
-			data->hctx->tags->rqs[rq->tag] = rq;
-		}
+		/*
+		 * Flush requests are special and go directly to the
+		 * dispatch list.
+		 */
+		if (!op_is_flush(op) && e->type->ops.mq.limit_depth)
+			e->type->ops.mq.limit_depth(op, data);
+	}
 
-		blk_mq_rq_ctx_init(data->q, data->ctx, rq, op);
-		return rq;
+	tag = blk_mq_get_tag(data);
+	if (tag == BLK_MQ_TAG_FAIL) {
+		blk_queue_exit(q);
+		return NULL;
 	}
 
-	return NULL;
+	rq = blk_mq_rq_ctx_init(data, tag, op);
+	if (!op_is_flush(op)) {
+		rq->elv.icq = NULL;
+		if (e && e->type->ops.mq.prepare_request) {
+			if (e->type->icq_cache && rq_ioc(bio))
+				blk_mq_sched_assign_ioc(rq, bio);
+
+			e->type->ops.mq.prepare_request(rq, bio);
+			rq->rq_flags |= RQF_ELVPRIV;
+		}
+	}
+	data->hctx->queued++;
+	return rq;
 }
-EXPORT_SYMBOL_GPL(__blk_mq_alloc_request);
 
-struct request *blk_mq_alloc_request(struct request_queue *q, int rw,
+struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op,
 		unsigned int flags)
 {
 	struct blk_mq_alloc_data alloc_data = { .flags = flags };
@@ -289,7 +357,7 @@ struct request *blk_mq_alloc_request(struct request_queue *q, int rw,
 	if (ret)
 		return ERR_PTR(ret);
 
-	rq = blk_mq_sched_get_request(q, NULL, rw, &alloc_data);
+	rq = blk_mq_get_request(q, NULL, op, &alloc_data);
 
 	blk_mq_put_ctx(alloc_data.ctx);
 	blk_queue_exit(q);
@@ -304,8 +372,8 @@ struct request *blk_mq_alloc_request(struct request_queue *q, int rw,
 }
 EXPORT_SYMBOL(blk_mq_alloc_request);
 
-struct request *blk_mq_alloc_request_hctx(struct request_queue *q, int rw,
-		unsigned int flags, unsigned int hctx_idx)
+struct request *blk_mq_alloc_request_hctx(struct request_queue *q,
+		unsigned int op, unsigned int flags, unsigned int hctx_idx)
 {
 	struct blk_mq_alloc_data alloc_data = { .flags = flags };
 	struct request *rq;
@@ -340,7 +408,7 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q, int rw,
 	cpu = cpumask_first(alloc_data.hctx->cpumask);
 	alloc_data.ctx = __blk_mq_get_ctx(q, cpu);
 
-	rq = blk_mq_sched_get_request(q, NULL, rw, &alloc_data);
+	rq = blk_mq_get_request(q, NULL, op, &alloc_data);
 
 	blk_queue_exit(q);
 
@@ -351,17 +419,28 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q, int rw,
 }
 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx);
 
-void __blk_mq_finish_request(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
-			     struct request *rq)
+void blk_mq_free_request(struct request *rq)
 {
-	const int sched_tag = rq->internal_tag;
 	struct request_queue *q = rq->q;
+	struct elevator_queue *e = q->elevator;
+	struct blk_mq_ctx *ctx = rq->mq_ctx;
+	struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
+	const int sched_tag = rq->internal_tag;
 
+	if (rq->rq_flags & RQF_ELVPRIV) {
+		if (e && e->type->ops.mq.finish_request)
+			e->type->ops.mq.finish_request(rq);
+		if (rq->elv.icq) {
+			put_io_context(rq->elv.icq->ioc);
+			rq->elv.icq = NULL;
+		}
+	}
+
+	ctx->rq_completed[rq_is_sync(rq)]++;
 	if (rq->rq_flags & RQF_MQ_INFLIGHT)
 		atomic_dec(&hctx->nr_active);
 
 	wbt_done(q->rq_wb, &rq->issue_stat);
-	rq->rq_flags = 0;
 
 	clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
 	clear_bit(REQ_ATOM_POLL_SLEPT, &rq->atomic_flags);
@@ -372,29 +451,9 @@ void __blk_mq_finish_request(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
 	blk_mq_sched_restart(hctx);
 	blk_queue_exit(q);
 }
-
-static void blk_mq_finish_hctx_request(struct blk_mq_hw_ctx *hctx,
-				     struct request *rq)
-{
-	struct blk_mq_ctx *ctx = rq->mq_ctx;
-
-	ctx->rq_completed[rq_is_sync(rq)]++;
-	__blk_mq_finish_request(hctx, ctx, rq);
-}
-
-void blk_mq_finish_request(struct request *rq)
-{
-	blk_mq_finish_hctx_request(blk_mq_map_queue(rq->q, rq->mq_ctx->cpu), rq);
-}
-EXPORT_SYMBOL_GPL(blk_mq_finish_request);
-
-void blk_mq_free_request(struct request *rq)
-{
-	blk_mq_sched_put_request(rq);
-}
 EXPORT_SYMBOL_GPL(blk_mq_free_request);
 
-inline void __blk_mq_end_request(struct request *rq, int error)
+inline void __blk_mq_end_request(struct request *rq, blk_status_t error)
 {
 	blk_account_io_done(rq);
 
@@ -409,7 +468,7 @@ inline void __blk_mq_end_request(struct request *rq, int error)
 }
 EXPORT_SYMBOL(__blk_mq_end_request);
 
-void blk_mq_end_request(struct request *rq, int error)
+void blk_mq_end_request(struct request *rq, blk_status_t error)
 {
 	if (blk_update_request(rq, error, blk_rq_bytes(rq)))
 		BUG();
@@ -753,50 +812,6 @@ static void blk_mq_timeout_work(struct work_struct *work)
 	blk_queue_exit(q);
 }
 
-/*
- * Reverse check our software queue for entries that we could potentially
- * merge with. Currently includes a hand-wavy stop count of 8, to not spend
- * too much time checking for merges.
- */
-static bool blk_mq_attempt_merge(struct request_queue *q,
-				 struct blk_mq_ctx *ctx, struct bio *bio)
-{
-	struct request *rq;
-	int checked = 8;
-
-	list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) {
-		bool merged = false;
-
-		if (!checked--)
-			break;
-
-		if (!blk_rq_merge_ok(rq, bio))
-			continue;
-
-		switch (blk_try_merge(rq, bio)) {
-		case ELEVATOR_BACK_MERGE:
-			if (blk_mq_sched_allow_merge(q, rq, bio))
-				merged = bio_attempt_back_merge(q, rq, bio);
-			break;
-		case ELEVATOR_FRONT_MERGE:
-			if (blk_mq_sched_allow_merge(q, rq, bio))
-				merged = bio_attempt_front_merge(q, rq, bio);
-			break;
-		case ELEVATOR_DISCARD_MERGE:
-			merged = bio_attempt_discard_merge(q, rq, bio);
-			break;
-		default:
-			continue;
-		}
-
-		if (merged)
-			ctx->rq_merged++;
-		return merged;
-	}
-
-	return false;
-}
-
 struct flush_busy_ctx_data {
 	struct blk_mq_hw_ctx *hctx;
 	struct list_head *list;
@@ -968,7 +983,7 @@ bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list)
 {
 	struct blk_mq_hw_ctx *hctx;
 	struct request *rq;
-	int errors, queued, ret = BLK_MQ_RQ_QUEUE_OK;
+	int errors, queued;
 
 	if (list_empty(list))
 		return false;
@@ -979,6 +994,7 @@ bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list)
 	errors = queued = 0;
 	do {
 		struct blk_mq_queue_data bd;
+		blk_status_t ret;
 
 		rq = list_first_entry(list, struct request, queuelist);
 		if (!blk_mq_get_driver_tag(rq, &hctx, false)) {
@@ -1019,25 +1035,20 @@ bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list)
 		}
 
 		ret = q->mq_ops->queue_rq(hctx, &bd);
-		switch (ret) {
-		case BLK_MQ_RQ_QUEUE_OK:
-			queued++;
-			break;
-		case BLK_MQ_RQ_QUEUE_BUSY:
+		if (ret == BLK_STS_RESOURCE) {
 			blk_mq_put_driver_tag_hctx(hctx, rq);
 			list_add(&rq->queuelist, list);
 			__blk_mq_requeue_request(rq);
 			break;
-		default:
-			pr_err("blk-mq: bad return on queue: %d\n", ret);
-		case BLK_MQ_RQ_QUEUE_ERROR:
+		}
+
+		if (unlikely(ret != BLK_STS_OK)) {
 			errors++;
-			blk_mq_end_request(rq, -EIO);
-			break;
+			blk_mq_end_request(rq, BLK_STS_IOERR);
+			continue;
 		}
 
-		if (ret == BLK_MQ_RQ_QUEUE_BUSY)
-			break;
+		queued++;
 	} while (!list_empty(list));
 
 	hctx->dispatched[queued_to_index(queued)]++;
@@ -1075,7 +1086,7 @@ bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list)
 		 * - blk_mq_run_hw_queue() checks whether or not a queue has
 		 *   been stopped before rerunning a queue.
 		 * - Some but not all block drivers stop a queue before
-		 *   returning BLK_MQ_RQ_QUEUE_BUSY. Two exceptions are scsi-mq
+		 *   returning BLK_STS_RESOURCE. Two exceptions are scsi-mq
 		 *   and dm-rq.
 		 */
 		if (!blk_mq_sched_needs_restart(hctx) &&
@@ -1100,9 +1111,9 @@ static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
 	} else {
 		might_sleep();
 
-		srcu_idx = srcu_read_lock(&hctx->queue_rq_srcu);
+		srcu_idx = srcu_read_lock(hctx->queue_rq_srcu);
 		blk_mq_sched_dispatch_requests(hctx);
-		srcu_read_unlock(&hctx->queue_rq_srcu, srcu_idx);
+		srcu_read_unlock(hctx->queue_rq_srcu, srcu_idx);
 	}
 }
 
@@ -1134,8 +1145,10 @@ static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
 static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async,
 					unsigned long msecs)
 {
-	if (unlikely(blk_mq_hctx_stopped(hctx) ||
-		     !blk_mq_hw_queue_mapped(hctx)))
+	if (WARN_ON_ONCE(!blk_mq_hw_queue_mapped(hctx)))
+		return;
+
+	if (unlikely(blk_mq_hctx_stopped(hctx)))
 		return;
 
 	if (!async && !(hctx->flags & BLK_MQ_F_BLOCKING)) {
@@ -1201,34 +1214,39 @@ bool blk_mq_queue_stopped(struct request_queue *q)
 }
 EXPORT_SYMBOL(blk_mq_queue_stopped);
 
-static void __blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx, bool sync)
+/*
+ * This function is often used for pausing .queue_rq() by driver when
+ * there isn't enough resource or some conditions aren't satisfied, and
+ * BLK_MQ_RQ_QUEUE_BUSY is usually returned.
+ *
+ * We do not guarantee that dispatch can be drained or blocked
+ * after blk_mq_stop_hw_queue() returns. Please use
+ * blk_mq_quiesce_queue() for that requirement.
+ */
+void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
 {
-	if (sync)
-		cancel_delayed_work_sync(&hctx->run_work);
-	else
-		cancel_delayed_work(&hctx->run_work);
+	cancel_delayed_work(&hctx->run_work);
 
 	set_bit(BLK_MQ_S_STOPPED, &hctx->state);
 }
-
-void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
-{
-	__blk_mq_stop_hw_queue(hctx, false);
-}
 EXPORT_SYMBOL(blk_mq_stop_hw_queue);
 
-static void __blk_mq_stop_hw_queues(struct request_queue *q, bool sync)
+/*
+ * This function is often used for pausing .queue_rq() by driver when
+ * there isn't enough resource or some conditions aren't satisfied, and
+ * BLK_MQ_RQ_QUEUE_BUSY is usually returned.
+ *
+ * We do not guarantee that dispatch can be drained or blocked
+ * after blk_mq_stop_hw_queues() returns. Please use
+ * blk_mq_quiesce_queue() for that requirement.
+ */
+void blk_mq_stop_hw_queues(struct request_queue *q)
 {
 	struct blk_mq_hw_ctx *hctx;
 	int i;
 
 	queue_for_each_hw_ctx(q, hctx, i)
-		__blk_mq_stop_hw_queue(hctx, sync);
-}
-
-void blk_mq_stop_hw_queues(struct request_queue *q)
-{
-	__blk_mq_stop_hw_queues(q, false);
+		blk_mq_stop_hw_queue(hctx);
 }
 EXPORT_SYMBOL(blk_mq_stop_hw_queues);
 
@@ -1295,7 +1313,7 @@ static void blk_mq_run_work_fn(struct work_struct *work)
 
 void blk_mq_delay_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
 {
-	if (unlikely(!blk_mq_hw_queue_mapped(hctx)))
+	if (WARN_ON_ONCE(!blk_mq_hw_queue_mapped(hctx)))
 		return;
 
 	/*
@@ -1317,6 +1335,8 @@ static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx,
 {
 	struct blk_mq_ctx *ctx = rq->mq_ctx;
 
+	lockdep_assert_held(&ctx->lock);
+
 	trace_block_rq_insert(hctx->queue, rq);
 
 	if (at_head)
@@ -1330,6 +1350,8 @@ void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
 {
 	struct blk_mq_ctx *ctx = rq->mq_ctx;
 
+	lockdep_assert_held(&ctx->lock);
+
 	__blk_mq_insert_req_list(hctx, rq, at_head);
 	blk_mq_hctx_mark_pending(hctx, ctx);
 }
@@ -1427,30 +1449,13 @@ static inline bool hctx_allow_merges(struct blk_mq_hw_ctx *hctx)
 		!blk_queue_nomerges(hctx->queue);
 }
 
-static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx *hctx,
-					 struct blk_mq_ctx *ctx,
-					 struct request *rq, struct bio *bio)
+static inline void blk_mq_queue_io(struct blk_mq_hw_ctx *hctx,
+				   struct blk_mq_ctx *ctx,
+				   struct request *rq)
 {
-	if (!hctx_allow_merges(hctx) || !bio_mergeable(bio)) {
-		blk_mq_bio_to_request(rq, bio);
-		spin_lock(&ctx->lock);
-insert_rq:
-		__blk_mq_insert_request(hctx, rq, false);
-		spin_unlock(&ctx->lock);
-		return false;
-	} else {
-		struct request_queue *q = hctx->queue;
-
-		spin_lock(&ctx->lock);
-		if (!blk_mq_attempt_merge(q, ctx, bio)) {
-			blk_mq_bio_to_request(rq, bio);
-			goto insert_rq;
-		}
-
-		spin_unlock(&ctx->lock);
-		__blk_mq_finish_request(hctx, ctx, rq);
-		return true;
-	}
+	spin_lock(&ctx->lock);
+	__blk_mq_insert_request(hctx, rq, false);
+	spin_unlock(&ctx->lock);
 }
 
 static blk_qc_t request_to_qc_t(struct blk_mq_hw_ctx *hctx, struct request *rq)
@@ -1471,10 +1476,11 @@ static void __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
 		.last = true,
 	};
 	blk_qc_t new_cookie;
-	int ret;
+	blk_status_t ret;
 	bool run_queue = true;
 
-	if (blk_mq_hctx_stopped(hctx)) {
+	/* RCU or SRCU read lock is needed before checking quiesced flag */
+	if (blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q)) {
 		run_queue = false;
 		goto insert;
 	}
@@ -1493,18 +1499,19 @@ static void __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
 	 * would have done
 	 */
 	ret = q->mq_ops->queue_rq(hctx, &bd);
-	if (ret == BLK_MQ_RQ_QUEUE_OK) {
+	switch (ret) {
+	case BLK_STS_OK:
 		*cookie = new_cookie;
 		return;
-	}
-
-	if (ret == BLK_MQ_RQ_QUEUE_ERROR) {
+	case BLK_STS_RESOURCE:
+		__blk_mq_requeue_request(rq);
+		goto insert;
+	default:
 		*cookie = BLK_QC_T_NONE;
-		blk_mq_end_request(rq, -EIO);
+		blk_mq_end_request(rq, ret);
 		return;
 	}
 
-	__blk_mq_requeue_request(rq);
 insert:
 	blk_mq_sched_insert_request(rq, false, run_queue, false, may_sleep);
 }
@@ -1521,9 +1528,9 @@ static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
 
 		might_sleep();
 
-		srcu_idx = srcu_read_lock(&hctx->queue_rq_srcu);
+		srcu_idx = srcu_read_lock(hctx->queue_rq_srcu);
 		__blk_mq_try_issue_directly(hctx, rq, cookie, true);
-		srcu_read_unlock(&hctx->queue_rq_srcu, srcu_idx);
+		srcu_read_unlock(hctx->queue_rq_srcu, srcu_idx);
 	}
 }
 
@@ -1541,7 +1548,7 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
 
 	blk_queue_bounce(q, &bio);
 
-	blk_queue_split(q, &bio, q->bio_split);
+	blk_queue_split(q, &bio);
 
 	if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
 		bio_io_error(bio);
@@ -1559,9 +1566,11 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
 
 	trace_block_getrq(q, bio, bio->bi_opf);
 
-	rq = blk_mq_sched_get_request(q, bio, bio->bi_opf, &data);
+	rq = blk_mq_get_request(q, bio, bio->bi_opf, &data);
 	if (unlikely(!rq)) {
 		__wbt_done(q->rq_wb, wb_acct);
+		if (bio->bi_opf & REQ_NOWAIT)
+			bio_wouldblock_error(bio);
 		return BLK_QC_T_NONE;
 	}
 
@@ -1639,11 +1648,12 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
 		blk_mq_put_ctx(data.ctx);
 		blk_mq_bio_to_request(rq, bio);
 		blk_mq_sched_insert_request(rq, false, true, true, true);
-	} else if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
+	} else {
 		blk_mq_put_ctx(data.ctx);
+		blk_mq_bio_to_request(rq, bio);
+		blk_mq_queue_io(data.hctx, data.ctx, rq);
 		blk_mq_run_hw_queue(data.hctx, true);
-	} else
-		blk_mq_put_ctx(data.ctx);
+	}
 
 	return cookie;
 }
@@ -1866,7 +1876,7 @@ static void blk_mq_exit_hctx(struct request_queue *q,
 		set->ops->exit_hctx(hctx, hctx_idx);
 
 	if (hctx->flags & BLK_MQ_F_BLOCKING)
-		cleanup_srcu_struct(&hctx->queue_rq_srcu);
+		cleanup_srcu_struct(hctx->queue_rq_srcu);
 
 	blk_mq_remove_cpuhp(hctx);
 	blk_free_flush_queue(hctx->fq);
@@ -1900,7 +1910,6 @@ static int blk_mq_init_hctx(struct request_queue *q,
 	spin_lock_init(&hctx->lock);
 	INIT_LIST_HEAD(&hctx->dispatch);
 	hctx->queue = q;
-	hctx->queue_num = hctx_idx;
 	hctx->flags = set->flags & ~BLK_MQ_F_TAG_SHARED;
 
 	cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD, &hctx->cpuhp_dead);
@@ -1939,7 +1948,7 @@ static int blk_mq_init_hctx(struct request_queue *q,
 		goto free_fq;
 
 	if (hctx->flags & BLK_MQ_F_BLOCKING)
-		init_srcu_struct(&hctx->queue_rq_srcu);
+		init_srcu_struct(hctx->queue_rq_srcu);
 
 	blk_mq_debugfs_register_hctx(q, hctx);
 
@@ -2224,6 +2233,20 @@ struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
 }
 EXPORT_SYMBOL(blk_mq_init_queue);
 
+static int blk_mq_hw_ctx_size(struct blk_mq_tag_set *tag_set)
+{
+	int hw_ctx_size = sizeof(struct blk_mq_hw_ctx);
+
+	BUILD_BUG_ON(ALIGN(offsetof(struct blk_mq_hw_ctx, queue_rq_srcu),
+			   __alignof__(struct blk_mq_hw_ctx)) !=
+		     sizeof(struct blk_mq_hw_ctx));
+
+	if (tag_set->flags & BLK_MQ_F_BLOCKING)
+		hw_ctx_size += sizeof(struct srcu_struct);
+
+	return hw_ctx_size;
+}
+
 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
 						struct request_queue *q)
 {
@@ -2238,7 +2261,7 @@ static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
 			continue;
 
 		node = blk_mq_hw_queue_to_node(q->mq_map, i);
-		hctxs[i] = kzalloc_node(sizeof(struct blk_mq_hw_ctx),
+		hctxs[i] = kzalloc_node(blk_mq_hw_ctx_size(set),
 					GFP_KERNEL, node);
 		if (!hctxs[i])
 			break;
diff --git a/block/blk-mq.h b/block/blk-mq.h
index cc67b48e3551..1a06fdf9fd4d 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -128,17 +128,6 @@ static inline struct blk_mq_tags *blk_mq_tags_from_data(struct blk_mq_alloc_data
 	return data->hctx->tags;
 }
 
-/*
- * Internal helpers for request allocation/init/free
- */
-void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx,
-			struct request *rq, unsigned int op);
-void __blk_mq_finish_request(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
-				struct request *rq);
-void blk_mq_finish_request(struct request *rq);
-struct request *__blk_mq_alloc_request(struct blk_mq_alloc_data *data,
-					unsigned int op);
-
 static inline bool blk_mq_hctx_stopped(struct blk_mq_hw_ctx *hctx)
 {
 	return test_bit(BLK_MQ_S_STOPPED, &hctx->state);
diff --git a/block/blk-settings.c b/block/blk-settings.c
index 4fa81ed383ca..be1f115b538b 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -172,11 +172,6 @@ void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn)
 	q->nr_batching = BLK_BATCH_REQ;
 
 	blk_set_default_limits(&q->limits);
-
-	/*
-	 * by default assume old behaviour and bounce for any highmem page
-	 */
-	blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH);
 }
 EXPORT_SYMBOL(blk_queue_make_request);
 
diff --git a/block/blk-tag.c b/block/blk-tag.c
index 07cc329fa4b0..2290f65b9d73 100644
--- a/block/blk-tag.c
+++ b/block/blk-tag.c
@@ -258,15 +258,14 @@ EXPORT_SYMBOL(blk_queue_resize_tags);
  *    all transfers have been done for a request. It's important to call
  *    this function before end_that_request_last(), as that will put the
  *    request back on the free list thus corrupting the internal tag list.
- *
- *  Notes:
- *   queue lock must be held.
  **/
 void blk_queue_end_tag(struct request_queue *q, struct request *rq)
 {
 	struct blk_queue_tag *bqt = q->queue_tags;
 	unsigned tag = rq->tag; /* negative tags invalid */
 
+	lockdep_assert_held(q->queue_lock);
+
 	BUG_ON(tag >= bqt->real_max_depth);
 
 	list_del_init(&rq->queuelist);
@@ -307,9 +306,6 @@ EXPORT_SYMBOL(blk_queue_end_tag);
  *    calling this function.  The request will also be removed from
  *    the request queue, so it's the drivers responsibility to readd
  *    it if it should need to be restarted for some reason.
- *
- *  Notes:
- *   queue lock must be held.
  **/
 int blk_queue_start_tag(struct request_queue *q, struct request *rq)
 {
@@ -317,6 +313,8 @@ int blk_queue_start_tag(struct request_queue *q, struct request *rq)
 	unsigned max_depth;
 	int tag;
 
+	lockdep_assert_held(q->queue_lock);
+
 	if (unlikely((rq->rq_flags & RQF_QUEUED))) {
 		printk(KERN_ERR
 		       "%s: request %p for device [%s] already tagged %d",
@@ -389,14 +387,13 @@ EXPORT_SYMBOL(blk_queue_start_tag);
  *   Hardware conditions may dictate a need to stop all pending requests.
  *   In this case, we will safely clear the block side of the tag queue and
  *   readd all requests to the request queue in the right order.
- *
- *  Notes:
- *   queue lock must be held.
  **/
 void blk_queue_invalidate_tags(struct request_queue *q)
 {
 	struct list_head *tmp, *n;
 
+	lockdep_assert_held(q->queue_lock);
+
 	list_for_each_safe(tmp, n, &q->tag_busy_list)
 		blk_requeue_request(q, list_entry_rq(tmp));
 }
diff --git a/block/blk-timeout.c b/block/blk-timeout.c
index cbff183f3d9f..17ec83bb0900 100644
--- a/block/blk-timeout.c
+++ b/block/blk-timeout.c
@@ -189,13 +189,15 @@ unsigned long blk_rq_timeout(unsigned long timeout)
  * Notes:
  *    Each request has its own timer, and as it is added to the queue, we
  *    set up the timer. When the request completes, we cancel the timer.
- *    Queue lock must be held for the non-mq case, mq case doesn't care.
  */
 void blk_add_timer(struct request *req)
 {
 	struct request_queue *q = req->q;
 	unsigned long expiry;
 
+	if (!q->mq_ops)
+		lockdep_assert_held(q->queue_lock);
+
 	/* blk-mq has its own handler, so we don't need ->rq_timed_out_fn */
 	if (!q->mq_ops && !q->rq_timed_out_fn)
 		return;
diff --git a/block/blk.h b/block/blk.h
index 83c8e1100525..01ebb8185f6b 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -143,6 +143,8 @@ static inline struct request *__elv_next_request(struct request_queue *q)
 	struct request *rq;
 	struct blk_flush_queue *fq = blk_get_flush_queue(q, NULL);
 
+	WARN_ON_ONCE(q->mq_ops);
+
 	while (1) {
 		if (!list_empty(&q->queue_head)) {
 			rq = list_entry_rq(q->queue_head.next);
@@ -334,4 +336,17 @@ static inline void blk_throtl_bio_endio(struct bio *bio) { }
 static inline void blk_throtl_stat_add(struct request *rq, u64 time) { }
 #endif
 
+#ifdef CONFIG_BOUNCE
+extern int init_emergency_isa_pool(void);
+extern void blk_queue_bounce(struct request_queue *q, struct bio **bio);
+#else
+static inline int init_emergency_isa_pool(void)
+{
+	return 0;
+}
+static inline void blk_queue_bounce(struct request_queue *q, struct bio **bio)
+{
+}
+#endif /* CONFIG_BOUNCE */
+
 #endif /* BLK_INTERNAL_H */
diff --git a/block/bounce.c b/block/bounce.c
index 1cb5dd3a5da1..5793c2dc1a15 100644
--- a/block/bounce.c
+++ b/block/bounce.c
@@ -22,10 +22,12 @@
 #include <asm/tlbflush.h>
 
 #include <trace/events/block.h>
+#include "blk.h"
 
 #define POOL_SIZE	64
 #define ISA_POOL_SIZE	16
 
+static struct bio_set *bounce_bio_set, *bounce_bio_split;
 static mempool_t *page_pool, *isa_page_pool;
 
 #if defined(CONFIG_HIGHMEM) || defined(CONFIG_NEED_BOUNCE_POOL)
@@ -40,6 +42,14 @@ static __init int init_emergency_pool(void)
 	BUG_ON(!page_pool);
 	pr_info("pool size: %d pages\n", POOL_SIZE);
 
+	bounce_bio_set = bioset_create(BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
+	BUG_ON(!bounce_bio_set);
+	if (bioset_integrity_create(bounce_bio_set, BIO_POOL_SIZE))
+		BUG_ON(1);
+
+	bounce_bio_split = bioset_create(BIO_POOL_SIZE, 0, 0);
+	BUG_ON(!bounce_bio_split);
+
 	return 0;
 }
 
@@ -143,7 +153,7 @@ static void bounce_end_io(struct bio *bio, mempool_t *pool)
 		mempool_free(bvec->bv_page, pool);
 	}
 
-	bio_orig->bi_error = bio->bi_error;
+	bio_orig->bi_status = bio->bi_status;
 	bio_endio(bio_orig);
 	bio_put(bio);
 }
@@ -163,7 +173,7 @@ static void __bounce_end_io_read(struct bio *bio, mempool_t *pool)
 {
 	struct bio *bio_orig = bio->bi_private;
 
-	if (!bio->bi_error)
+	if (!bio->bi_status)
 		copy_to_high_bio_irq(bio_orig, bio);
 
 	bounce_end_io(bio, pool);
@@ -186,20 +196,31 @@ static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig,
 	int rw = bio_data_dir(*bio_orig);
 	struct bio_vec *to, from;
 	struct bvec_iter iter;
-	unsigned i;
-
-	bio_for_each_segment(from, *bio_orig, iter)
-		if (page_to_pfn(from.bv_page) > queue_bounce_pfn(q))
-			goto bounce;
+	unsigned i = 0;
+	bool bounce = false;
+	int sectors = 0;
+
+	bio_for_each_segment(from, *bio_orig, iter) {
+		if (i++ < BIO_MAX_PAGES)
+			sectors += from.bv_len >> 9;
+		if (page_to_pfn(from.bv_page) > q->limits.bounce_pfn)
+			bounce = true;
+	}
+	if (!bounce)
+		return;
 
-	return;
-bounce:
-	bio = bio_clone_bioset(*bio_orig, GFP_NOIO, fs_bio_set);
+	if (sectors < bio_sectors(*bio_orig)) {
+		bio = bio_split(*bio_orig, sectors, GFP_NOIO, bounce_bio_split);
+		bio_chain(bio, *bio_orig);
+		generic_make_request(*bio_orig);
+		*bio_orig = bio;
+	}
+	bio = bio_clone_bioset(*bio_orig, GFP_NOIO, bounce_bio_set);
 
 	bio_for_each_segment_all(to, bio, i) {
 		struct page *page = to->bv_page;
 
-		if (page_to_pfn(page) <= queue_bounce_pfn(q))
+		if (page_to_pfn(page) <= q->limits.bounce_pfn)
 			continue;
 
 		to->bv_page = mempool_alloc(pool, q->bounce_gfp);
@@ -251,7 +272,7 @@ void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig)
 	 * don't waste time iterating over bio segments
 	 */
 	if (!(q->bounce_gfp & GFP_DMA)) {
-		if (queue_bounce_pfn(q) >= blk_max_pfn)
+		if (q->limits.bounce_pfn >= blk_max_pfn)
 			return;
 		pool = page_pool;
 	} else {
@@ -264,5 +285,3 @@ void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig)
 	 */
 	__blk_queue_bounce(q, bio_orig, pool);
 }
-
-EXPORT_SYMBOL(blk_queue_bounce);
diff --git a/block/bsg-lib.c b/block/bsg-lib.c
index 0a23dbba2d30..c4513b23f57a 100644
--- a/block/bsg-lib.c
+++ b/block/bsg-lib.c
@@ -37,7 +37,7 @@ static void bsg_destroy_job(struct kref *kref)
 	struct bsg_job *job = container_of(kref, struct bsg_job, kref);
 	struct request *rq = job->req;
 
-	blk_end_request_all(rq, scsi_req(rq)->result);
+	blk_end_request_all(rq, BLK_STS_OK);
 
 	put_device(job->dev);	/* release reference for the request */
 
@@ -202,7 +202,7 @@ static void bsg_request_fn(struct request_queue *q)
 		ret = bsg_create_job(dev, req);
 		if (ret) {
 			scsi_req(req)->result = ret;
-			blk_end_request_all(req, ret);
+			blk_end_request_all(req, BLK_STS_OK);
 			spin_lock_irq(q->queue_lock);
 			continue;
 		}
@@ -246,6 +246,7 @@ struct request_queue *bsg_setup_queue(struct device *dev, char *name,
 	q->bsg_job_size = dd_job_size;
 	q->bsg_job_fn = job_fn;
 	queue_flag_set_unlocked(QUEUE_FLAG_BIDI, q);
+	queue_flag_set_unlocked(QUEUE_FLAG_SCSI_PASSTHROUGH, q);
 	blk_queue_softirq_done(q, bsg_softirq_done);
 	blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT);
 
diff --git a/block/bsg.c b/block/bsg.c
index 6fd08544d77e..37663b664666 100644
--- a/block/bsg.c
+++ b/block/bsg.c
@@ -236,7 +236,6 @@ bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr, fmode_t has_write_perm)
 	rq = blk_get_request(q, op, GFP_KERNEL);
 	if (IS_ERR(rq))
 		return rq;
-	scsi_req_init(rq);
 
 	ret = blk_fill_sgv4_hdr_rq(q, rq, hdr, bd, has_write_perm);
 	if (ret)
@@ -294,14 +293,14 @@ out:
  * async completion call-back from the block layer, when scsi/ide/whatever
  * calls end_that_request_last() on a request
  */
-static void bsg_rq_end_io(struct request *rq, int uptodate)
+static void bsg_rq_end_io(struct request *rq, blk_status_t status)
 {
 	struct bsg_command *bc = rq->end_io_data;
 	struct bsg_device *bd = bc->bd;
 	unsigned long flags;
 
-	dprintk("%s: finished rq %p bc %p, bio %p stat %d\n",
-		bd->name, rq, bc, bc->bio, uptodate);
+	dprintk("%s: finished rq %p bc %p, bio %p\n",
+		bd->name, rq, bc, bc->bio);
 
 	bc->hdr.duration = jiffies_to_msecs(jiffies - bc->hdr.duration);
 
@@ -750,6 +749,12 @@ static struct bsg_device *bsg_add_device(struct inode *inode,
 #ifdef BSG_DEBUG
 	unsigned char buf[32];
 #endif
+
+	if (!blk_queue_scsi_passthrough(rq)) {
+		WARN_ONCE(true, "Attempt to register a non-SCSI queue\n");
+		return ERR_PTR(-EINVAL);
+	}
+
 	if (!blk_get_queue(rq))
 		return ERR_PTR(-ENXIO);
 
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index b7e9c7feeab2..3d5c28945719 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -982,15 +982,6 @@ static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
 	return min_vdisktime;
 }
 
-static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
-{
-	s64 delta = (s64)(vdisktime - min_vdisktime);
-	if (delta < 0)
-		min_vdisktime = vdisktime;
-
-	return min_vdisktime;
-}
-
 static void update_min_vdisktime(struct cfq_rb_root *st)
 {
 	struct cfq_group *cfqg;
diff --git a/block/elevator.c b/block/elevator.c
index dac99fbfc273..4bb2f0c93fa6 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -681,6 +681,7 @@ void __elv_add_request(struct request_queue *q, struct request *rq, int where)
 		 */
 		if (elv_attempt_insert_merge(q, rq))
 			break;
+		/* fall through */
 	case ELEVATOR_INSERT_SORT:
 		BUG_ON(blk_rq_is_passthrough(rq));
 		rq->rq_flags |= RQF_SORTED;
diff --git a/block/genhd.c b/block/genhd.c
index d252d29fe837..7f520fa25d16 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -36,7 +36,7 @@ struct kobject *block_depr;
 static DEFINE_SPINLOCK(ext_devt_lock);
 static DEFINE_IDR(ext_devt_idr);
 
-static struct device_type disk_type;
+static const struct device_type disk_type;
 
 static void disk_check_events(struct disk_events *ev,
 			      unsigned int *clearing_ptr);
@@ -1183,7 +1183,7 @@ static char *block_devnode(struct device *dev, umode_t *mode,
 	return NULL;
 }
 
-static struct device_type disk_type = {
+static const struct device_type disk_type = {
 	.name		= "disk",
 	.groups		= disk_attr_groups,
 	.release	= disk_release,
diff --git a/block/ioprio.c b/block/ioprio.c
index 4b120c9cf7e8..6f5d0b6625e3 100644
--- a/block/ioprio.c
+++ b/block/ioprio.c
@@ -75,7 +75,8 @@ SYSCALL_DEFINE3(ioprio_set, int, which, int, who, int, ioprio)
 		case IOPRIO_CLASS_RT:
 			if (!capable(CAP_SYS_ADMIN))
 				return -EPERM;
-			/* fall through, rt has prio field too */
+			/* fall through */
+			/* rt has prio field too */
 		case IOPRIO_CLASS_BE:
 			if (data >= IOPRIO_BE_NR || data < 0)
 				return -EINVAL;
diff --git a/block/kyber-iosched.c b/block/kyber-iosched.c
index b9faabc75fdb..a9f6fd3fab8e 100644
--- a/block/kyber-iosched.c
+++ b/block/kyber-iosched.c
@@ -426,33 +426,29 @@ static void rq_clear_domain_token(struct kyber_queue_data *kqd,
 	}
 }
 
-static struct request *kyber_get_request(struct request_queue *q,
-					 unsigned int op,
-					 struct blk_mq_alloc_data *data)
+static void kyber_limit_depth(unsigned int op, struct blk_mq_alloc_data *data)
 {
-	struct kyber_queue_data *kqd = q->elevator->elevator_data;
-	struct request *rq;
-
 	/*
 	 * We use the scheduler tags as per-hardware queue queueing tokens.
 	 * Async requests can be limited at this stage.
 	 */
-	if (!op_is_sync(op))
+	if (!op_is_sync(op)) {
+		struct kyber_queue_data *kqd = data->q->elevator->elevator_data;
+
 		data->shallow_depth = kqd->async_depth;
+	}
+}
 
-	rq = __blk_mq_alloc_request(data, op);
-	if (rq)
-		rq_set_domain_token(rq, -1);
-	return rq;
+static void kyber_prepare_request(struct request *rq, struct bio *bio)
+{
+	rq_set_domain_token(rq, -1);
 }
 
-static void kyber_put_request(struct request *rq)
+static void kyber_finish_request(struct request *rq)
 {
-	struct request_queue *q = rq->q;
-	struct kyber_queue_data *kqd = q->elevator->elevator_data;
+	struct kyber_queue_data *kqd = rq->q->elevator->elevator_data;
 
 	rq_clear_domain_token(kqd, rq);
-	blk_mq_finish_request(rq);
 }
 
 static void kyber_completed_request(struct request *rq)
@@ -815,8 +811,9 @@ static struct elevator_type kyber_sched = {
 		.exit_sched = kyber_exit_sched,
 		.init_hctx = kyber_init_hctx,
 		.exit_hctx = kyber_exit_hctx,
-		.get_request = kyber_get_request,
-		.put_request = kyber_put_request,
+		.limit_depth = kyber_limit_depth,
+		.prepare_request = kyber_prepare_request,
+		.finish_request = kyber_finish_request,
 		.completed_request = kyber_completed_request,
 		.dispatch_request = kyber_dispatch_request,
 		.has_work = kyber_has_work,
diff --git a/block/scsi_ioctl.c b/block/scsi_ioctl.c
index 4a294a5f7fab..7440de44dd85 100644
--- a/block/scsi_ioctl.c
+++ b/block/scsi_ioctl.c
@@ -326,7 +326,6 @@ static int sg_io(struct request_queue *q, struct gendisk *bd_disk,
 	if (IS_ERR(rq))
 		return PTR_ERR(rq);
 	req = scsi_req(rq);
-	scsi_req_init(rq);
 
 	if (hdr->cmd_len > BLK_MAX_CDB) {
 		req->cmd = kzalloc(hdr->cmd_len, GFP_KERNEL);
@@ -456,7 +455,6 @@ int sg_scsi_ioctl(struct request_queue *q, struct gendisk *disk, fmode_t mode,
 		goto error_free_buffer;
 	}
 	req = scsi_req(rq);
-	scsi_req_init(rq);
 
 	cmdlen = COMMAND_SIZE(opcode);
 
@@ -542,7 +540,6 @@ static int __blk_send_generic(struct request_queue *q, struct gendisk *bd_disk,
 	rq = blk_get_request(q, REQ_OP_SCSI_OUT, __GFP_RECLAIM);
 	if (IS_ERR(rq))
 		return PTR_ERR(rq);
-	scsi_req_init(rq);
 	rq->timeout = BLK_DEFAULT_SG_TIMEOUT;
 	scsi_req(rq)->cmd[0] = cmd;
 	scsi_req(rq)->cmd[4] = data;
@@ -744,10 +741,14 @@ int scsi_cmd_blk_ioctl(struct block_device *bd, fmode_t mode,
 }
 EXPORT_SYMBOL(scsi_cmd_blk_ioctl);
 
-void scsi_req_init(struct request *rq)
+/**
+ * scsi_req_init - initialize certain fields of a scsi_request structure
+ * @req: Pointer to a scsi_request structure.
+ * Initializes .__cmd[], .cmd, .cmd_len and .sense_len but no other members
+ * of struct scsi_request.
+ */
+void scsi_req_init(struct scsi_request *req)
 {
-	struct scsi_request *req = scsi_req(rq);
-
 	memset(req->__cmd, 0, sizeof(req->__cmd));
 	req->cmd = req->__cmd;
 	req->cmd_len = BLK_MAX_CDB;
diff --git a/block/t10-pi.c b/block/t10-pi.c
index 680c6d636298..3416dadf7b15 100644
--- a/block/t10-pi.c
+++ b/block/t10-pi.c
@@ -46,8 +46,8 @@ static __be16 t10_pi_ip_fn(void *data, unsigned int len)
  * 16 bit app tag, 32 bit reference tag. Type 3 does not define the ref
  * tag.
  */
-static int t10_pi_generate(struct blk_integrity_iter *iter, csum_fn *fn,
-			   unsigned int type)
+static blk_status_t t10_pi_generate(struct blk_integrity_iter *iter,
+		csum_fn *fn, unsigned int type)
 {
 	unsigned int i;
 
@@ -67,11 +67,11 @@ static int t10_pi_generate(struct blk_integrity_iter *iter, csum_fn *fn,
 		iter->seed++;
 	}
 
-	return 0;
+	return BLK_STS_OK;
 }
 
-static int t10_pi_verify(struct blk_integrity_iter *iter, csum_fn *fn,
-				unsigned int type)
+static blk_status_t t10_pi_verify(struct blk_integrity_iter *iter,
+		csum_fn *fn, unsigned int type)
 {
 	unsigned int i;
 
@@ -91,7 +91,7 @@ static int t10_pi_verify(struct blk_integrity_iter *iter, csum_fn *fn,
 				       "(rcvd %u)\n", iter->disk_name,
 				       (unsigned long long)
 				       iter->seed, be32_to_cpu(pi->ref_tag));
-				return -EILSEQ;
+				return BLK_STS_PROTECTION;
 			}
 			break;
 		case 3:
@@ -108,7 +108,7 @@ static int t10_pi_verify(struct blk_integrity_iter *iter, csum_fn *fn,
 			       "(rcvd %04x, want %04x)\n", iter->disk_name,
 			       (unsigned long long)iter->seed,
 			       be16_to_cpu(pi->guard_tag), be16_to_cpu(csum));
-			return -EILSEQ;
+			return BLK_STS_PROTECTION;
 		}
 
 next:
@@ -117,45 +117,45 @@ next:
 		iter->seed++;
 	}
 
-	return 0;
+	return BLK_STS_OK;
 }
 
-static int t10_pi_type1_generate_crc(struct blk_integrity_iter *iter)
+static blk_status_t t10_pi_type1_generate_crc(struct blk_integrity_iter *iter)
 {
 	return t10_pi_generate(iter, t10_pi_crc_fn, 1);
 }
 
-static int t10_pi_type1_generate_ip(struct blk_integrity_iter *iter)
+static blk_status_t t10_pi_type1_generate_ip(struct blk_integrity_iter *iter)
 {
 	return t10_pi_generate(iter, t10_pi_ip_fn, 1);
 }
 
-static int t10_pi_type1_verify_crc(struct blk_integrity_iter *iter)
+static blk_status_t t10_pi_type1_verify_crc(struct blk_integrity_iter *iter)
 {
 	return t10_pi_verify(iter, t10_pi_crc_fn, 1);
 }
 
-static int t10_pi_type1_verify_ip(struct blk_integrity_iter *iter)
+static blk_status_t t10_pi_type1_verify_ip(struct blk_integrity_iter *iter)
 {
 	return t10_pi_verify(iter, t10_pi_ip_fn, 1);
 }
 
-static int t10_pi_type3_generate_crc(struct blk_integrity_iter *iter)
+static blk_status_t t10_pi_type3_generate_crc(struct blk_integrity_iter *iter)
 {
 	return t10_pi_generate(iter, t10_pi_crc_fn, 3);
 }
 
-static int t10_pi_type3_generate_ip(struct blk_integrity_iter *iter)
+static blk_status_t t10_pi_type3_generate_ip(struct blk_integrity_iter *iter)
 {
 	return t10_pi_generate(iter, t10_pi_ip_fn, 3);
 }
 
-static int t10_pi_type3_verify_crc(struct blk_integrity_iter *iter)
+static blk_status_t t10_pi_type3_verify_crc(struct blk_integrity_iter *iter)
 {
 	return t10_pi_verify(iter, t10_pi_crc_fn, 3);
 }
 
-static int t10_pi_type3_verify_ip(struct blk_integrity_iter *iter)
+static blk_status_t t10_pi_type3_verify_ip(struct blk_integrity_iter *iter)
 {
 	return t10_pi_verify(iter, t10_pi_ip_fn, 3);
 }