1 files changed, 214 insertions, 161 deletions

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 0835f4d8d42e..a12b1763508d 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -30,6 +30,7 @@
 #include <trace/events/block.h>
 
 #include <linux/blk-mq.h>
+#include <linux/t10-pi.h>
 #include "blk.h"
 #include "blk-mq.h"
 #include "blk-mq-debugfs.h"
@@ -44,12 +45,12 @@ static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb);
 
 static int blk_mq_poll_stats_bkt(const struct request *rq)
 {
-	int ddir, bytes, bucket;
+	int ddir, sectors, bucket;
 
 	ddir = rq_data_dir(rq);
-	bytes = blk_rq_bytes(rq);
+	sectors = blk_rq_stats_sectors(rq);
 
-	bucket = ddir + 2*(ilog2(bytes) - 9);
+	bucket = ddir + 2 * ilog2(sectors);
 
 	if (bucket < 0)
 		return -1;
@@ -92,7 +93,7 @@ static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,
 
 struct mq_inflight {
 	struct hd_struct *part;
-	unsigned int *inflight;
+	unsigned int inflight[2];
 };
 
 static bool blk_mq_check_inflight(struct blk_mq_hw_ctx *hctx,
@@ -101,45 +102,29 @@ static bool blk_mq_check_inflight(struct blk_mq_hw_ctx *hctx,
 {
 	struct mq_inflight *mi = priv;
 
-	/*
-	 * index[0] counts the specific partition that was asked for.
-	 */
 	if (rq->part == mi->part)
-		mi->inflight[0]++;
+		mi->inflight[rq_data_dir(rq)]++;
 
 	return true;
 }
 
 unsigned int blk_mq_in_flight(struct request_queue *q, struct hd_struct *part)
 {
-	unsigned inflight[2];
-	struct mq_inflight mi = { .part = part, .inflight = inflight, };
+	struct mq_inflight mi = { .part = part };
 
-	inflight[0] = inflight[1] = 0;
 	blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight, &mi);
 
-	return inflight[0];
-}
-
-static bool blk_mq_check_inflight_rw(struct blk_mq_hw_ctx *hctx,
-				     struct request *rq, void *priv,
-				     bool reserved)
-{
-	struct mq_inflight *mi = priv;
-
-	if (rq->part == mi->part)
-		mi->inflight[rq_data_dir(rq)]++;
-
-	return true;
+	return mi.inflight[0] + mi.inflight[1];
 }
 
 void blk_mq_in_flight_rw(struct request_queue *q, struct hd_struct *part,
 			 unsigned int inflight[2])
 {
-	struct mq_inflight mi = { .part = part, .inflight = inflight, };
+	struct mq_inflight mi = { .part = part };
 
-	inflight[0] = inflight[1] = 0;
-	blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight_rw, &mi);
+	blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight, &mi);
+	inflight[0] = mi.inflight[0];
+	inflight[1] = mi.inflight[1];
 }
 
 void blk_freeze_queue_start(struct request_queue *q)
@@ -275,23 +260,17 @@ void blk_mq_wake_waiters(struct request_queue *q)
 			blk_mq_tag_wakeup_all(hctx->tags, true);
 }
 
-bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx)
-{
-	return blk_mq_has_free_tags(hctx->tags);
-}
-EXPORT_SYMBOL(blk_mq_can_queue);
-
 /*
- * Only need start/end time stamping if we have stats enabled, or using
- * an IO scheduler.
+ * Only need start/end time stamping if we have iostat or
+ * blk stats enabled, or using an IO scheduler.
  */
 static inline bool blk_mq_need_time_stamp(struct request *rq)
 {
-	return (rq->rq_flags & RQF_IO_STAT) || rq->q->elevator;
+	return (rq->rq_flags & (RQF_IO_STAT | RQF_STATS)) || rq->q->elevator;
 }
 
 static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
-		unsigned int tag, unsigned int op)
+		unsigned int tag, unsigned int op, u64 alloc_time_ns)
 {
 	struct blk_mq_tags *tags = blk_mq_tags_from_data(data);
 	struct request *rq = tags->static_rqs[tag];
@@ -325,11 +304,15 @@ static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
 	RB_CLEAR_NODE(&rq->rb_node);
 	rq->rq_disk = NULL;
 	rq->part = NULL;
+#ifdef CONFIG_BLK_RQ_ALLOC_TIME
+	rq->alloc_time_ns = alloc_time_ns;
+#endif
 	if (blk_mq_need_time_stamp(rq))
 		rq->start_time_ns = ktime_get_ns();
 	else
 		rq->start_time_ns = 0;
 	rq->io_start_time_ns = 0;
+	rq->stats_sectors = 0;
 	rq->nr_phys_segments = 0;
 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 	rq->nr_integrity_segments = 0;
@@ -356,8 +339,14 @@ static struct request *blk_mq_get_request(struct request_queue *q,
 	struct request *rq;
 	unsigned int tag;
 	bool clear_ctx_on_error = false;
+	u64 alloc_time_ns = 0;
 
 	blk_queue_enter_live(q);
+
+	/* alloc_time includes depth and tag waits */
+	if (blk_queue_rq_alloc_time(q))
+		alloc_time_ns = ktime_get_ns();
+
 	data->q = q;
 	if (likely(!data->ctx)) {
 		data->ctx = blk_mq_get_ctx(q);
@@ -393,7 +382,7 @@ static struct request *blk_mq_get_request(struct request_queue *q,
 		return NULL;
 	}
 
-	rq = blk_mq_rq_ctx_init(data, tag, data->cmd_flags);
+	rq = blk_mq_rq_ctx_init(data, tag, data->cmd_flags, alloc_time_ns);
 	if (!op_is_flush(data->cmd_flags)) {
 		rq->elv.icq = NULL;
 		if (e && e->type->ops.prepare_request) {
@@ -652,19 +641,14 @@ bool blk_mq_complete_request(struct request *rq)
 }
 EXPORT_SYMBOL(blk_mq_complete_request);
 
-void blk_mq_complete_request_sync(struct request *rq)
-{
-	WRITE_ONCE(rq->state, MQ_RQ_COMPLETE);
-	rq->q->mq_ops->complete(rq);
-}
-EXPORT_SYMBOL_GPL(blk_mq_complete_request_sync);
-
-int blk_mq_request_started(struct request *rq)
-{
-	return blk_mq_rq_state(rq) != MQ_RQ_IDLE;
-}
-EXPORT_SYMBOL_GPL(blk_mq_request_started);
-
+/**
+ * blk_mq_start_request - Start processing a request
+ * @rq: Pointer to request to be started
+ *
+ * Function used by device drivers to notify the block layer that a request
+ * is going to be processed now, so blk layer can do proper initializations
+ * such as starting the timeout timer.
+ */
 void blk_mq_start_request(struct request *rq)
 {
 	struct request_queue *q = rq->q;
@@ -673,9 +657,7 @@ void blk_mq_start_request(struct request *rq)
 
 	if (test_bit(QUEUE_FLAG_STATS, &q->queue_flags)) {
 		rq->io_start_time_ns = ktime_get_ns();
-#ifdef CONFIG_BLK_DEV_THROTTLING_LOW
-		rq->throtl_size = blk_rq_sectors(rq);
-#endif
+		rq->stats_sectors = blk_rq_sectors(rq);
 		rq->rq_flags |= RQF_STATS;
 		rq_qos_issue(q, rq);
 	}
@@ -693,6 +675,11 @@ void blk_mq_start_request(struct request *rq)
 		 */
 		rq->nr_phys_segments++;
 	}
+
+#ifdef CONFIG_BLK_DEV_INTEGRITY
+	if (blk_integrity_rq(rq) && req_op(rq) == REQ_OP_WRITE)
+		q->integrity.profile->prepare_fn(rq);
+#endif
 }
 EXPORT_SYMBOL(blk_mq_start_request);
 
@@ -905,7 +892,10 @@ static bool blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
 	 */
 	if (blk_mq_req_expired(rq, next))
 		blk_mq_rq_timed_out(rq, reserved);
-	if (refcount_dec_and_test(&rq->ref))
+
+	if (is_flush_rq(rq, hctx))
+		rq->end_io(rq, 0);
+	else if (refcount_dec_and_test(&rq->ref))
 		__blk_mq_free_request(rq);
 
 	return true;
@@ -1048,7 +1038,7 @@ bool blk_mq_get_driver_tag(struct request *rq)
 	bool shared;
 
 	if (rq->tag != -1)
-		goto done;
+		return true;
 
 	if (blk_mq_tag_is_reserved(data.hctx->sched_tags, rq->internal_tag))
 		data.flags |= BLK_MQ_REQ_RESERVED;
@@ -1063,7 +1053,6 @@ bool blk_mq_get_driver_tag(struct request *rq)
 		data.hctx->tags->rqs[rq->tag] = rq;
 	}
 
-done:
 	return rq->tag != -1;
 }
 
@@ -1346,6 +1335,12 @@ bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list,
 	return (queued + errors) != 0;
 }
 
+/**
+ * __blk_mq_run_hw_queue - Run a hardware queue.
+ * @hctx: Pointer to the hardware queue to run.
+ *
+ * Send pending requests to the hardware.
+ */
 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
 {
 	int srcu_idx;
@@ -1443,6 +1438,15 @@ select_cpu:
 	return next_cpu;
 }
 
+/**
+ * __blk_mq_delay_run_hw_queue - Run (or schedule to run) a hardware queue.
+ * @hctx: Pointer to the hardware queue to run.
+ * @async: If we want to run the queue asynchronously.
+ * @msecs: Microseconds of delay to wait before running the queue.
+ *
+ * If !@async, try to run the queue now. Else, run the queue asynchronously and
+ * with a delay of @msecs.
+ */
 static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async,
 					unsigned long msecs)
 {
@@ -1464,13 +1468,29 @@ static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async,
 				    msecs_to_jiffies(msecs));
 }
 
+/**
+ * blk_mq_delay_run_hw_queue - Run a hardware queue asynchronously.
+ * @hctx: Pointer to the hardware queue to run.
+ * @msecs: Microseconds of delay to wait before running the queue.
+ *
+ * Run a hardware queue asynchronously with a delay of @msecs.
+ */
 void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
 {
 	__blk_mq_delay_run_hw_queue(hctx, true, msecs);
 }
 EXPORT_SYMBOL(blk_mq_delay_run_hw_queue);
 
-bool blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
+/**
+ * blk_mq_run_hw_queue - Start to run a hardware queue.
+ * @hctx: Pointer to the hardware queue to run.
+ * @async: If we want to run the queue asynchronously.
+ *
+ * Check if the request queue is not in a quiesced state and if there are
+ * pending requests to be sent. If this is true, run the queue to send requests
+ * to hardware.
+ */
+void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
 {
 	int srcu_idx;
 	bool need_run;
@@ -1488,15 +1508,16 @@ bool blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
 		blk_mq_hctx_has_pending(hctx);
 	hctx_unlock(hctx, srcu_idx);
 
-	if (need_run) {
+	if (need_run)
 		__blk_mq_delay_run_hw_queue(hctx, async, 0);
-		return true;
-	}
-
-	return false;
 }
 EXPORT_SYMBOL(blk_mq_run_hw_queue);
 
+/**
+ * blk_mq_run_hw_queue - Run all hardware queues in a request queue.
+ * @q: Pointer to the request queue to run.
+ * @async: If we want to run the queue asynchronously.
+ */
 void blk_mq_run_hw_queues(struct request_queue *q, bool async)
 {
 	struct blk_mq_hw_ctx *hctx;
@@ -1648,7 +1669,11 @@ void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
 	blk_mq_hctx_mark_pending(hctx, ctx);
 }
 
-/*
+/**
+ * blk_mq_request_bypass_insert - Insert a request at dispatch list.
+ * @rq: Pointer to request to be inserted.
+ * @run_queue: If we should run the hardware queue after inserting the request.
+ *
  * Should only be used carefully, when the caller knows we want to
  * bypass a potential IO scheduler on the target device.
  */
@@ -1691,28 +1716,20 @@ static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b)
 	struct request *rqa = container_of(a, struct request, queuelist);
 	struct request *rqb = container_of(b, struct request, queuelist);
 
-	if (rqa->mq_ctx < rqb->mq_ctx)
-		return -1;
-	else if (rqa->mq_ctx > rqb->mq_ctx)
-		return 1;
-	else if (rqa->mq_hctx < rqb->mq_hctx)
-		return -1;
-	else if (rqa->mq_hctx > rqb->mq_hctx)
-		return 1;
+	if (rqa->mq_ctx != rqb->mq_ctx)
+		return rqa->mq_ctx > rqb->mq_ctx;
+	if (rqa->mq_hctx != rqb->mq_hctx)
+		return rqa->mq_hctx > rqb->mq_hctx;
 
 	return blk_rq_pos(rqa) > blk_rq_pos(rqb);
 }
 
 void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
 {
-	struct blk_mq_hw_ctx *this_hctx;
-	struct blk_mq_ctx *this_ctx;
-	struct request_queue *this_q;
-	struct request *rq;
 	LIST_HEAD(list);
-	LIST_HEAD(rq_list);
-	unsigned int depth;
 
+	if (list_empty(&plug->mq_list))
+		return;
 	list_splice_init(&plug->mq_list, &list);
 
 	if (plug->rq_count > 2 && plug->multiple_queues)
@@ -1720,42 +1737,27 @@ void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
 
 	plug->rq_count = 0;
 
-	this_q = NULL;
-	this_hctx = NULL;
-	this_ctx = NULL;
-	depth = 0;
-
-	while (!list_empty(&list)) {
-		rq = list_entry_rq(list.next);
-		list_del_init(&rq->queuelist);
-		BUG_ON(!rq->q);
-		if (rq->mq_hctx != this_hctx || rq->mq_ctx != this_ctx) {
-			if (this_hctx) {
-				trace_block_unplug(this_q, depth, !from_schedule);
-				blk_mq_sched_insert_requests(this_hctx, this_ctx,
-								&rq_list,
-								from_schedule);
-			}
-
-			this_q = rq->q;
-			this_ctx = rq->mq_ctx;
-			this_hctx = rq->mq_hctx;
-			depth = 0;
+	do {
+		struct list_head rq_list;
+		struct request *rq, *head_rq = list_entry_rq(list.next);
+		struct list_head *pos = &head_rq->queuelist; /* skip first */
+		struct blk_mq_hw_ctx *this_hctx = head_rq->mq_hctx;
+		struct blk_mq_ctx *this_ctx = head_rq->mq_ctx;
+		unsigned int depth = 1;
+
+		list_for_each_continue(pos, &list) {
+			rq = list_entry_rq(pos);
+			BUG_ON(!rq->q);
+			if (rq->mq_hctx != this_hctx || rq->mq_ctx != this_ctx)
+				break;
+			depth++;
 		}
 
-		depth++;
-		list_add_tail(&rq->queuelist, &rq_list);
-	}
-
-	/*
-	 * If 'this_hctx' is set, we know we have entries to complete
-	 * on 'rq_list'. Do those.
-	 */
-	if (this_hctx) {
-		trace_block_unplug(this_q, depth, !from_schedule);
+		list_cut_before(&rq_list, &list, pos);
+		trace_block_unplug(head_rq->q, depth, !from_schedule);
 		blk_mq_sched_insert_requests(this_hctx, this_ctx, &rq_list,
 						from_schedule);
-	}
+	} while(!list_empty(&list));
 }
 
 static void blk_mq_bio_to_request(struct request *rq, struct bio *bio,
@@ -1851,6 +1853,17 @@ insert:
 	return BLK_STS_OK;
 }
 
+/**
+ * blk_mq_try_issue_directly - Try to send a request directly to device driver.
+ * @hctx: Pointer of the associated hardware queue.
+ * @rq: Pointer to request to be sent.
+ * @cookie: Request queue cookie.
+ *
+ * If the device has enough resources to accept a new request now, send the
+ * request directly to device driver. Else, insert at hctx->dispatch queue, so
+ * we can try send it another time in the future. Requests inserted at this
+ * queue have higher priority.
+ */
 static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
 		struct request *rq, blk_qc_t *cookie)
 {
@@ -1928,6 +1941,22 @@ static void blk_add_rq_to_plug(struct blk_plug *plug, struct request *rq)
 	}
 }
 
+/**
+ * blk_mq_make_request - Create and send a request to block device.
+ * @q: Request queue pointer.
+ * @bio: Bio pointer.
+ *
+ * Builds up a request structure from @q and @bio and send to the device. The
+ * request may not be queued directly to hardware if:
+ * * This request can be merged with another one
+ * * We want to place request at plug queue for possible future merging
+ * * There is an IO scheduler active at this queue
+ *
+ * It will not queue the request if there is an error with the bio, or at the
+ * request creation.
+ *
+ * Returns: Request queue cookie.
+ */
 static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
 {
 	const int is_sync = op_is_sync(bio->bi_opf);
@@ -1973,13 +2002,17 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
 
 	plug = blk_mq_plug(q, bio);
 	if (unlikely(is_flush_fua)) {
-		/* bypass scheduler for flush rq */
+		/* Bypass scheduler for flush requests */
 		blk_insert_flush(rq);
 		blk_mq_run_hw_queue(data.hctx, true);
-	} else if (plug && (q->nr_hw_queues == 1 || q->mq_ops->commit_rqs)) {
+	} else if (plug && (q->nr_hw_queues == 1 || q->mq_ops->commit_rqs ||
+				!blk_queue_nonrot(q))) {
 		/*
 		 * Use plugging if we have a ->commit_rqs() hook as well, as
 		 * we know the driver uses bd->last in a smart fashion.
+		 *
+		 * Use normal plugging if this disk is slow HDD, as sequential
+		 * IO may benefit a lot from plug merging.
 		 */
 		unsigned int request_count = plug->rq_count;
 		struct request *last = NULL;
@@ -1996,6 +2029,9 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
 		}
 
 		blk_add_rq_to_plug(plug, rq);
+	} else if (q->elevator) {
+		/* Insert the request at the IO scheduler queue */
+		blk_mq_sched_insert_request(rq, false, true, true);
 	} else if (plug && !blk_queue_nomerges(q)) {
 		/*
 		 * We do limited plugging. If the bio can be merged, do that.
@@ -2019,10 +2055,15 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
 			blk_mq_try_issue_directly(data.hctx, same_queue_rq,
 					&cookie);
 		}
-	} else if ((q->nr_hw_queues > 1 && is_sync) || (!q->elevator &&
-			!data.hctx->dispatch_busy)) {
+	} else if ((q->nr_hw_queues > 1 && is_sync) ||
+			!data.hctx->dispatch_busy) {
+		/*
+		 * There is no scheduler and we can try to send directly
+		 * to the hardware.
+		 */
 		blk_mq_try_issue_directly(data.hctx, rq, &cookie);
 	} else {
+		/* Default case. */
 		blk_mq_sched_insert_request(rq, false, true, true);
 	}
 
@@ -2453,11 +2494,6 @@ static void blk_mq_map_swqueue(struct request_queue *q)
 	struct blk_mq_ctx *ctx;
 	struct blk_mq_tag_set *set = q->tag_set;
 
-	/*
-	 * Avoid others reading imcomplete hctx->cpumask through sysfs
-	 */
-	mutex_lock(&q->sysfs_lock);
-
 	queue_for_each_hw_ctx(q, hctx, i) {
 		cpumask_clear(hctx->cpumask);
 		hctx->nr_ctx = 0;
@@ -2518,8 +2554,6 @@ static void blk_mq_map_swqueue(struct request_queue *q)
 					HCTX_TYPE_DEFAULT, i);
 	}
 
-	mutex_unlock(&q->sysfs_lock);
-
 	queue_for_each_hw_ctx(q, hctx, i) {
 		/*
 		 * If no software queues are mapped to this hardware queue,
@@ -2688,7 +2722,11 @@ struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
 	if (!uninit_q)
 		return ERR_PTR(-ENOMEM);
 
-	q = blk_mq_init_allocated_queue(set, uninit_q);
+	/*
+	 * Initialize the queue without an elevator. device_add_disk() will do
+	 * the initialization.
+	 */
+	q = blk_mq_init_allocated_queue(set, uninit_q, false);
 	if (IS_ERR(q))
 		blk_cleanup_queue(uninit_q);
 
@@ -2770,6 +2808,23 @@ static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
 	int i, j, end;
 	struct blk_mq_hw_ctx **hctxs = q->queue_hw_ctx;
 
+	if (q->nr_hw_queues < set->nr_hw_queues) {
+		struct blk_mq_hw_ctx **new_hctxs;
+
+		new_hctxs = kcalloc_node(set->nr_hw_queues,
+				       sizeof(*new_hctxs), GFP_KERNEL,
+				       set->numa_node);
+		if (!new_hctxs)
+			return;
+		if (hctxs)
+			memcpy(new_hctxs, hctxs, q->nr_hw_queues *
+			       sizeof(*hctxs));
+		q->queue_hw_ctx = new_hctxs;
+		q->nr_hw_queues = set->nr_hw_queues;
+		kfree(hctxs);
+		hctxs = new_hctxs;
+	}
+
 	/* protect against switching io scheduler  */
 	mutex_lock(&q->sysfs_lock);
 	for (i = 0; i < set->nr_hw_queues; i++) {
@@ -2825,21 +2880,9 @@ static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
 	mutex_unlock(&q->sysfs_lock);
 }
 
-/*
- * Maximum number of hardware queues we support. For single sets, we'll never
- * have more than the CPUs (software queues). For multiple sets, the tag_set
- * user may have set ->nr_hw_queues larger.
- */
-static unsigned int nr_hw_queues(struct blk_mq_tag_set *set)
-{
-	if (set->nr_maps == 1)
-		return nr_cpu_ids;
-
-	return max(set->nr_hw_queues, nr_cpu_ids);
-}
-
 struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
-						  struct request_queue *q)
+						  struct request_queue *q,
+						  bool elevator_init)
 {
 	/* mark the queue as mq asap */
 	q->mq_ops = set->ops;
@@ -2856,12 +2899,6 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
 	/* init q->mq_kobj and sw queues' kobjects */
 	blk_mq_sysfs_init(q);
 
-	q->nr_queues = nr_hw_queues(set);
-	q->queue_hw_ctx = kcalloc_node(q->nr_queues, sizeof(*(q->queue_hw_ctx)),
-						GFP_KERNEL, set->numa_node);
-	if (!q->queue_hw_ctx)
-		goto err_sys_init;
-
 	INIT_LIST_HEAD(&q->unused_hctx_list);
 	spin_lock_init(&q->unused_hctx_lock);
 
@@ -2901,19 +2938,14 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
 	blk_mq_add_queue_tag_set(set, q);
 	blk_mq_map_swqueue(q);
 
-	if (!(set->flags & BLK_MQ_F_NO_SCHED)) {
-		int ret;
-
-		ret = elevator_init_mq(q);
-		if (ret)
-			return ERR_PTR(ret);
-	}
+	if (elevator_init)
+		elevator_init_mq(q);
 
 	return q;
 
 err_hctxs:
 	kfree(q->queue_hw_ctx);
-err_sys_init:
+	q->nr_hw_queues = 0;
 	blk_mq_sysfs_deinit(q);
 err_poll:
 	blk_stat_free_callback(q->poll_cb);
@@ -3014,6 +3046,29 @@ static int blk_mq_update_queue_map(struct blk_mq_tag_set *set)
 	}
 }
 
+static int blk_mq_realloc_tag_set_tags(struct blk_mq_tag_set *set,
+				  int cur_nr_hw_queues, int new_nr_hw_queues)
+{
+	struct blk_mq_tags **new_tags;
+
+	if (cur_nr_hw_queues >= new_nr_hw_queues)
+		return 0;
+
+	new_tags = kcalloc_node(new_nr_hw_queues, sizeof(struct blk_mq_tags *),
+				GFP_KERNEL, set->numa_node);
+	if (!new_tags)
+		return -ENOMEM;
+
+	if (set->tags)
+		memcpy(new_tags, set->tags, cur_nr_hw_queues *
+		       sizeof(*set->tags));
+	kfree(set->tags);
+	set->tags = new_tags;
+	set->nr_hw_queues = new_nr_hw_queues;
+
+	return 0;
+}
+
 /*
  * Alloc a tag set to be associated with one or more request queues.
  * May fail with EINVAL for various error conditions. May adjust the
@@ -3067,9 +3122,7 @@ int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
 	if (set->nr_maps == 1 && set->nr_hw_queues > nr_cpu_ids)
 		set->nr_hw_queues = nr_cpu_ids;
 
-	set->tags = kcalloc_node(nr_hw_queues(set), sizeof(struct blk_mq_tags *),
-				 GFP_KERNEL, set->numa_node);
-	if (!set->tags)
+	if (blk_mq_realloc_tag_set_tags(set, 0, set->nr_hw_queues) < 0)
 		return -ENOMEM;
 
 	ret = -ENOMEM;
@@ -3110,7 +3163,7 @@ void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
 {
 	int i, j;
 
-	for (i = 0; i < nr_hw_queues(set); i++)
+	for (i = 0; i < set->nr_hw_queues; i++)
 		blk_mq_free_map_and_requests(set, i);
 
 	for (j = 0; j < set->nr_maps; j++) {
@@ -3255,10 +3308,6 @@ static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set,
 	list_for_each_entry(q, &set->tag_list, tag_set_list)
 		blk_mq_freeze_queue(q);
 	/*
-	 * Sync with blk_mq_queue_tag_busy_iter.
-	 */
-	synchronize_rcu();
-	/*
 	 * Switch IO scheduler to 'none', cleaning up the data associated
 	 * with the previous scheduler. We will switch back once we are done
 	 * updating the new sw to hw queue mappings.
@@ -3272,6 +3321,10 @@ static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set,
 		blk_mq_sysfs_unregister(q);
 	}
 
+	if (blk_mq_realloc_tag_set_tags(set, set->nr_hw_queues, nr_hw_queues) <
+	    0)
+		goto reregister;
+
 	prev_nr_hw_queues = set->nr_hw_queues;
 	set->nr_hw_queues = nr_hw_queues;
 	blk_mq_update_queue_map(set);
@@ -3288,6 +3341,7 @@ fallback:
 		blk_mq_map_swqueue(q);
 	}
 
+reregister:
 	list_for_each_entry(q, &set->tag_list, tag_set_list) {
 		blk_mq_sysfs_register(q);
 		blk_mq_debugfs_register_hctxs(q);
@@ -3411,15 +3465,14 @@ static bool blk_mq_poll_hybrid_sleep(struct request_queue *q,
 	kt = nsecs;
 
 	mode = HRTIMER_MODE_REL;
-	hrtimer_init_on_stack(&hs.timer, CLOCK_MONOTONIC, mode);
+	hrtimer_init_sleeper_on_stack(&hs, CLOCK_MONOTONIC, mode);
 	hrtimer_set_expires(&hs.timer, kt);
 
-	hrtimer_init_sleeper(&hs, current);
 	do {
 		if (blk_mq_rq_state(rq) == MQ_RQ_COMPLETE)
 			break;
 		set_current_state(TASK_UNINTERRUPTIBLE);
-		hrtimer_start_expires(&hs.timer, mode);
+		hrtimer_sleeper_start_expires(&hs, mode);
 		if (hs.task)
 			io_schedule();
 		hrtimer_cancel(&hs.timer);