1 // SPDX-License-Identifier: GPL-2.0
3 * Block multiqueue core code
5 * Copyright (C) 2013-2014 Jens Axboe
6 * Copyright (C) 2013-2014 Christoph Hellwig
8 #include <linux/kernel.h>
9 #include <linux/module.h>
10 #include <linux/backing-dev.h>
11 #include <linux/bio.h>
12 #include <linux/blkdev.h>
13 #include <linux/kmemleak.h>
15 #include <linux/init.h>
16 #include <linux/slab.h>
17 #include <linux/workqueue.h>
18 #include <linux/smp.h>
19 #include <linux/llist.h>
20 #include <linux/list_sort.h>
21 #include <linux/cpu.h>
22 #include <linux/cache.h>
23 #include <linux/sched/sysctl.h>
24 #include <linux/sched/topology.h>
25 #include <linux/sched/signal.h>
26 #include <linux/delay.h>
27 #include <linux/crash_dump.h>
28 #include <linux/prefetch.h>
29 #include <linux/blk-crypto.h>
31 #include <trace/events/block.h>
33 #include <linux/blk-mq.h>
34 #include <linux/t10-pi.h>
37 #include "blk-mq-debugfs.h"
38 #include "blk-mq-tag.h"
41 #include "blk-mq-sched.h"
42 #include "blk-rq-qos.h"
44 static DEFINE_PER_CPU(struct llist_head, blk_cpu_done);
46 static void blk_mq_poll_stats_start(struct request_queue *q);
47 static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb);
49 static int blk_mq_poll_stats_bkt(const struct request *rq)
51 int ddir, sectors, bucket;
53 ddir = rq_data_dir(rq);
54 sectors = blk_rq_stats_sectors(rq);
56 bucket = ddir + 2 * ilog2(sectors);
60 else if (bucket >= BLK_MQ_POLL_STATS_BKTS)
61 return ddir + BLK_MQ_POLL_STATS_BKTS - 2;
67 * Check if any of the ctx, dispatch list or elevator
68 * have pending work in this hardware queue.
70 static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx)
72 return !list_empty_careful(&hctx->dispatch) ||
73 sbitmap_any_bit_set(&hctx->ctx_map) ||
74 blk_mq_sched_has_work(hctx);
78 * Mark this ctx as having pending work in this hardware queue
80 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx *hctx,
81 struct blk_mq_ctx *ctx)
83 const int bit = ctx->index_hw[hctx->type];
85 if (!sbitmap_test_bit(&hctx->ctx_map, bit))
86 sbitmap_set_bit(&hctx->ctx_map, bit);
89 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,
90 struct blk_mq_ctx *ctx)
92 const int bit = ctx->index_hw[hctx->type];
94 sbitmap_clear_bit(&hctx->ctx_map, bit);
98 struct block_device *part;
99 unsigned int inflight[2];
102 static bool blk_mq_check_inflight(struct blk_mq_hw_ctx *hctx,
103 struct request *rq, void *priv,
106 struct mq_inflight *mi = priv;
108 if ((!mi->part->bd_partno || rq->part == mi->part) &&
109 blk_mq_rq_state(rq) == MQ_RQ_IN_FLIGHT)
110 mi->inflight[rq_data_dir(rq)]++;
115 unsigned int blk_mq_in_flight(struct request_queue *q,
116 struct block_device *part)
118 struct mq_inflight mi = { .part = part };
120 blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight, &mi);
122 return mi.inflight[0] + mi.inflight[1];
125 void blk_mq_in_flight_rw(struct request_queue *q, struct block_device *part,
126 unsigned int inflight[2])
128 struct mq_inflight mi = { .part = part };
130 blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight, &mi);
131 inflight[0] = mi.inflight[0];
132 inflight[1] = mi.inflight[1];
135 void blk_freeze_queue_start(struct request_queue *q)
137 mutex_lock(&q->mq_freeze_lock);
138 if (++q->mq_freeze_depth == 1) {
139 percpu_ref_kill(&q->q_usage_counter);
140 mutex_unlock(&q->mq_freeze_lock);
142 blk_mq_run_hw_queues(q, false);
144 mutex_unlock(&q->mq_freeze_lock);
147 EXPORT_SYMBOL_GPL(blk_freeze_queue_start);
149 void blk_mq_freeze_queue_wait(struct request_queue *q)
151 wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->q_usage_counter));
153 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait);
155 int blk_mq_freeze_queue_wait_timeout(struct request_queue *q,
156 unsigned long timeout)
158 return wait_event_timeout(q->mq_freeze_wq,
159 percpu_ref_is_zero(&q->q_usage_counter),
162 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout);
165 * Guarantee no request is in use, so we can change any data structure of
166 * the queue afterward.
168 void blk_freeze_queue(struct request_queue *q)
171 * In the !blk_mq case we are only calling this to kill the
172 * q_usage_counter, otherwise this increases the freeze depth
173 * and waits for it to return to zero. For this reason there is
174 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
175 * exported to drivers as the only user for unfreeze is blk_mq.
177 blk_freeze_queue_start(q);
178 blk_mq_freeze_queue_wait(q);
181 void blk_mq_freeze_queue(struct request_queue *q)
184 * ...just an alias to keep freeze and unfreeze actions balanced
185 * in the blk_mq_* namespace
189 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue);
191 void __blk_mq_unfreeze_queue(struct request_queue *q, bool force_atomic)
193 mutex_lock(&q->mq_freeze_lock);
195 q->q_usage_counter.data->force_atomic = true;
196 q->mq_freeze_depth--;
197 WARN_ON_ONCE(q->mq_freeze_depth < 0);
198 if (!q->mq_freeze_depth) {
199 percpu_ref_resurrect(&q->q_usage_counter);
200 wake_up_all(&q->mq_freeze_wq);
202 mutex_unlock(&q->mq_freeze_lock);
205 void blk_mq_unfreeze_queue(struct request_queue *q)
207 __blk_mq_unfreeze_queue(q, false);
209 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue);
212 * FIXME: replace the scsi_internal_device_*block_nowait() calls in the
213 * mpt3sas driver such that this function can be removed.
215 void blk_mq_quiesce_queue_nowait(struct request_queue *q)
217 blk_queue_flag_set(QUEUE_FLAG_QUIESCED, q);
219 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait);
222 * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished
225 * Note: this function does not prevent that the struct request end_io()
226 * callback function is invoked. Once this function is returned, we make
227 * sure no dispatch can happen until the queue is unquiesced via
228 * blk_mq_unquiesce_queue().
230 void blk_mq_quiesce_queue(struct request_queue *q)
232 struct blk_mq_hw_ctx *hctx;
236 blk_mq_quiesce_queue_nowait(q);
238 queue_for_each_hw_ctx(q, hctx, i) {
239 if (hctx->flags & BLK_MQ_F_BLOCKING)
240 synchronize_srcu(hctx->srcu);
247 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue);
250 * blk_mq_unquiesce_queue() - counterpart of blk_mq_quiesce_queue()
253 * This function recovers queue into the state before quiescing
254 * which is done by blk_mq_quiesce_queue.
256 void blk_mq_unquiesce_queue(struct request_queue *q)
258 blk_queue_flag_clear(QUEUE_FLAG_QUIESCED, q);
260 /* dispatch requests which are inserted during quiescing */
261 blk_mq_run_hw_queues(q, true);
263 EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue);
265 void blk_mq_wake_waiters(struct request_queue *q)
267 struct blk_mq_hw_ctx *hctx;
270 queue_for_each_hw_ctx(q, hctx, i)
271 if (blk_mq_hw_queue_mapped(hctx))
272 blk_mq_tag_wakeup_all(hctx->tags, true);
276 * Only need start/end time stamping if we have iostat or
277 * blk stats enabled, or using an IO scheduler.
279 static inline bool blk_mq_need_time_stamp(struct request *rq)
281 return (rq->rq_flags & (RQF_IO_STAT | RQF_STATS)) || rq->q->elevator;
284 static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
285 unsigned int tag, u64 alloc_time_ns)
287 struct blk_mq_tags *tags = blk_mq_tags_from_data(data);
288 struct request *rq = tags->static_rqs[tag];
290 if (data->q->elevator) {
291 rq->tag = BLK_MQ_NO_TAG;
292 rq->internal_tag = tag;
295 rq->internal_tag = BLK_MQ_NO_TAG;
298 /* csd/requeue_work/fifo_time is initialized before use */
300 rq->mq_ctx = data->ctx;
301 rq->mq_hctx = data->hctx;
303 rq->cmd_flags = data->cmd_flags;
304 if (data->flags & BLK_MQ_REQ_PM)
305 rq->rq_flags |= RQF_PM;
306 if (blk_queue_io_stat(data->q))
307 rq->rq_flags |= RQF_IO_STAT;
308 INIT_LIST_HEAD(&rq->queuelist);
309 INIT_HLIST_NODE(&rq->hash);
310 RB_CLEAR_NODE(&rq->rb_node);
313 #ifdef CONFIG_BLK_RQ_ALLOC_TIME
314 rq->alloc_time_ns = alloc_time_ns;
316 if (blk_mq_need_time_stamp(rq))
317 rq->start_time_ns = ktime_get_ns();
319 rq->start_time_ns = 0;
320 rq->io_start_time_ns = 0;
321 rq->stats_sectors = 0;
322 rq->nr_phys_segments = 0;
323 #if defined(CONFIG_BLK_DEV_INTEGRITY)
324 rq->nr_integrity_segments = 0;
326 blk_crypto_rq_set_defaults(rq);
327 /* tag was already set */
328 WRITE_ONCE(rq->deadline, 0);
333 rq->end_io_data = NULL;
335 data->ctx->rq_dispatched[op_is_sync(data->cmd_flags)]++;
336 refcount_set(&rq->ref, 1);
338 if (!op_is_flush(data->cmd_flags)) {
339 struct elevator_queue *e = data->q->elevator;
342 if (e && e->type->ops.prepare_request) {
343 if (e->type->icq_cache)
344 blk_mq_sched_assign_ioc(rq);
346 e->type->ops.prepare_request(rq);
347 rq->rq_flags |= RQF_ELVPRIV;
351 data->hctx->queued++;
355 static struct request *__blk_mq_alloc_request(struct blk_mq_alloc_data *data)
357 struct request_queue *q = data->q;
358 struct elevator_queue *e = q->elevator;
359 u64 alloc_time_ns = 0;
362 /* alloc_time includes depth and tag waits */
363 if (blk_queue_rq_alloc_time(q))
364 alloc_time_ns = ktime_get_ns();
366 if (data->cmd_flags & REQ_NOWAIT)
367 data->flags |= BLK_MQ_REQ_NOWAIT;
371 * Flush/passthrough requests are special and go directly to the
372 * dispatch list. Don't include reserved tags in the
373 * limiting, as it isn't useful.
375 if (!op_is_flush(data->cmd_flags) &&
376 !blk_op_is_passthrough(data->cmd_flags) &&
377 e->type->ops.limit_depth &&
378 !(data->flags & BLK_MQ_REQ_RESERVED))
379 e->type->ops.limit_depth(data->cmd_flags, data);
383 data->ctx = blk_mq_get_ctx(q);
384 data->hctx = blk_mq_map_queue(q, data->cmd_flags, data->ctx);
386 blk_mq_tag_busy(data->hctx);
389 * Waiting allocations only fail because of an inactive hctx. In that
390 * case just retry the hctx assignment and tag allocation as CPU hotplug
391 * should have migrated us to an online CPU by now.
393 tag = blk_mq_get_tag(data);
394 if (tag == BLK_MQ_NO_TAG) {
395 if (data->flags & BLK_MQ_REQ_NOWAIT)
399 * Give up the CPU and sleep for a random short time to ensure
400 * that thread using a realtime scheduling class are migrated
401 * off the CPU, and thus off the hctx that is going away.
406 return blk_mq_rq_ctx_init(data, tag, alloc_time_ns);
409 struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op,
410 blk_mq_req_flags_t flags)
412 struct blk_mq_alloc_data data = {
420 ret = blk_queue_enter(q, flags);
424 rq = __blk_mq_alloc_request(&data);
428 rq->__sector = (sector_t) -1;
429 rq->bio = rq->biotail = NULL;
433 return ERR_PTR(-EWOULDBLOCK);
435 EXPORT_SYMBOL(blk_mq_alloc_request);
437 struct request *blk_mq_alloc_request_hctx(struct request_queue *q,
438 unsigned int op, blk_mq_req_flags_t flags, unsigned int hctx_idx)
440 struct blk_mq_alloc_data data = {
445 u64 alloc_time_ns = 0;
450 /* alloc_time includes depth and tag waits */
451 if (blk_queue_rq_alloc_time(q))
452 alloc_time_ns = ktime_get_ns();
455 * If the tag allocator sleeps we could get an allocation for a
456 * different hardware context. No need to complicate the low level
457 * allocator for this for the rare use case of a command tied to
460 if (WARN_ON_ONCE(!(flags & (BLK_MQ_REQ_NOWAIT | BLK_MQ_REQ_RESERVED))))
461 return ERR_PTR(-EINVAL);
463 if (hctx_idx >= q->nr_hw_queues)
464 return ERR_PTR(-EIO);
466 ret = blk_queue_enter(q, flags);
471 * Check if the hardware context is actually mapped to anything.
472 * If not tell the caller that it should skip this queue.
475 data.hctx = q->queue_hw_ctx[hctx_idx];
476 if (!blk_mq_hw_queue_mapped(data.hctx))
478 cpu = cpumask_first_and(data.hctx->cpumask, cpu_online_mask);
479 data.ctx = __blk_mq_get_ctx(q, cpu);
482 blk_mq_tag_busy(data.hctx);
485 tag = blk_mq_get_tag(&data);
486 if (tag == BLK_MQ_NO_TAG)
488 return blk_mq_rq_ctx_init(&data, tag, alloc_time_ns);
494 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx);
496 static void __blk_mq_free_request(struct request *rq)
498 struct request_queue *q = rq->q;
499 struct blk_mq_ctx *ctx = rq->mq_ctx;
500 struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
501 const int sched_tag = rq->internal_tag;
503 blk_crypto_free_request(rq);
504 blk_pm_mark_last_busy(rq);
506 if (rq->tag != BLK_MQ_NO_TAG)
507 blk_mq_put_tag(hctx->tags, ctx, rq->tag);
508 if (sched_tag != BLK_MQ_NO_TAG)
509 blk_mq_put_tag(hctx->sched_tags, ctx, sched_tag);
510 blk_mq_sched_restart(hctx);
514 void blk_mq_free_request(struct request *rq)
516 struct request_queue *q = rq->q;
517 struct elevator_queue *e = q->elevator;
518 struct blk_mq_ctx *ctx = rq->mq_ctx;
519 struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
521 if (rq->rq_flags & RQF_ELVPRIV) {
522 if (e && e->type->ops.finish_request)
523 e->type->ops.finish_request(rq);
525 put_io_context(rq->elv.icq->ioc);
530 ctx->rq_completed[rq_is_sync(rq)]++;
531 if (rq->rq_flags & RQF_MQ_INFLIGHT)
532 __blk_mq_dec_active_requests(hctx);
534 if (unlikely(laptop_mode && !blk_rq_is_passthrough(rq)))
535 laptop_io_completion(q->disk->bdi);
539 WRITE_ONCE(rq->state, MQ_RQ_IDLE);
540 if (refcount_dec_and_test(&rq->ref))
541 __blk_mq_free_request(rq);
543 EXPORT_SYMBOL_GPL(blk_mq_free_request);
545 inline void __blk_mq_end_request(struct request *rq, blk_status_t error)
549 if (blk_mq_need_time_stamp(rq))
550 now = ktime_get_ns();
552 if (rq->rq_flags & RQF_STATS) {
553 blk_mq_poll_stats_start(rq->q);
554 blk_stat_add(rq, now);
557 blk_mq_sched_completed_request(rq, now);
559 blk_account_io_done(rq, now);
562 rq_qos_done(rq->q, rq);
563 rq->end_io(rq, error);
565 blk_mq_free_request(rq);
568 EXPORT_SYMBOL(__blk_mq_end_request);
570 void blk_mq_end_request(struct request *rq, blk_status_t error)
572 if (blk_update_request(rq, error, blk_rq_bytes(rq)))
574 __blk_mq_end_request(rq, error);
576 EXPORT_SYMBOL(blk_mq_end_request);
578 static void blk_complete_reqs(struct llist_head *list)
580 struct llist_node *entry = llist_reverse_order(llist_del_all(list));
581 struct request *rq, *next;
583 llist_for_each_entry_safe(rq, next, entry, ipi_list)
584 rq->q->mq_ops->complete(rq);
587 static __latent_entropy void blk_done_softirq(struct softirq_action *h)
589 blk_complete_reqs(this_cpu_ptr(&blk_cpu_done));
592 static int blk_softirq_cpu_dead(unsigned int cpu)
594 blk_complete_reqs(&per_cpu(blk_cpu_done, cpu));
598 static void __blk_mq_complete_request_remote(void *data)
600 __raise_softirq_irqoff(BLOCK_SOFTIRQ);
603 static inline bool blk_mq_complete_need_ipi(struct request *rq)
605 int cpu = raw_smp_processor_id();
607 if (!IS_ENABLED(CONFIG_SMP) ||
608 !test_bit(QUEUE_FLAG_SAME_COMP, &rq->q->queue_flags))
611 * With force threaded interrupts enabled, raising softirq from an SMP
612 * function call will always result in waking the ksoftirqd thread.
613 * This is probably worse than completing the request on a different
616 if (force_irqthreads())
619 /* same CPU or cache domain? Complete locally */
620 if (cpu == rq->mq_ctx->cpu ||
621 (!test_bit(QUEUE_FLAG_SAME_FORCE, &rq->q->queue_flags) &&
622 cpus_share_cache(cpu, rq->mq_ctx->cpu)))
625 /* don't try to IPI to an offline CPU */
626 return cpu_online(rq->mq_ctx->cpu);
629 static void blk_mq_complete_send_ipi(struct request *rq)
631 struct llist_head *list;
634 cpu = rq->mq_ctx->cpu;
635 list = &per_cpu(blk_cpu_done, cpu);
636 if (llist_add(&rq->ipi_list, list)) {
637 INIT_CSD(&rq->csd, __blk_mq_complete_request_remote, rq);
638 smp_call_function_single_async(cpu, &rq->csd);
642 static void blk_mq_raise_softirq(struct request *rq)
644 struct llist_head *list;
647 list = this_cpu_ptr(&blk_cpu_done);
648 if (llist_add(&rq->ipi_list, list))
649 raise_softirq(BLOCK_SOFTIRQ);
653 bool blk_mq_complete_request_remote(struct request *rq)
655 WRITE_ONCE(rq->state, MQ_RQ_COMPLETE);
658 * For a polled request, always complete locallly, it's pointless
659 * to redirect the completion.
661 if (rq->cmd_flags & REQ_HIPRI)
664 if (blk_mq_complete_need_ipi(rq)) {
665 blk_mq_complete_send_ipi(rq);
669 if (rq->q->nr_hw_queues == 1) {
670 blk_mq_raise_softirq(rq);
675 EXPORT_SYMBOL_GPL(blk_mq_complete_request_remote);
678 * blk_mq_complete_request - end I/O on a request
679 * @rq: the request being processed
682 * Complete a request by scheduling the ->complete_rq operation.
684 void blk_mq_complete_request(struct request *rq)
686 if (!blk_mq_complete_request_remote(rq))
687 rq->q->mq_ops->complete(rq);
689 EXPORT_SYMBOL(blk_mq_complete_request);
691 static void hctx_unlock(struct blk_mq_hw_ctx *hctx, int srcu_idx)
692 __releases(hctx->srcu)
694 if (!(hctx->flags & BLK_MQ_F_BLOCKING))
697 srcu_read_unlock(hctx->srcu, srcu_idx);
700 static void hctx_lock(struct blk_mq_hw_ctx *hctx, int *srcu_idx)
701 __acquires(hctx->srcu)
703 if (!(hctx->flags & BLK_MQ_F_BLOCKING)) {
704 /* shut up gcc false positive */
708 *srcu_idx = srcu_read_lock(hctx->srcu);
712 * blk_mq_start_request - Start processing a request
713 * @rq: Pointer to request to be started
715 * Function used by device drivers to notify the block layer that a request
716 * is going to be processed now, so blk layer can do proper initializations
717 * such as starting the timeout timer.
719 void blk_mq_start_request(struct request *rq)
721 struct request_queue *q = rq->q;
723 trace_block_rq_issue(rq);
725 if (test_bit(QUEUE_FLAG_STATS, &q->queue_flags)) {
726 rq->io_start_time_ns = ktime_get_ns();
727 rq->stats_sectors = blk_rq_sectors(rq);
728 rq->rq_flags |= RQF_STATS;
732 WARN_ON_ONCE(blk_mq_rq_state(rq) != MQ_RQ_IDLE);
735 WRITE_ONCE(rq->state, MQ_RQ_IN_FLIGHT);
737 #ifdef CONFIG_BLK_DEV_INTEGRITY
738 if (blk_integrity_rq(rq) && req_op(rq) == REQ_OP_WRITE)
739 q->integrity.profile->prepare_fn(rq);
742 EXPORT_SYMBOL(blk_mq_start_request);
744 static void __blk_mq_requeue_request(struct request *rq)
746 struct request_queue *q = rq->q;
748 blk_mq_put_driver_tag(rq);
750 trace_block_rq_requeue(rq);
751 rq_qos_requeue(q, rq);
753 if (blk_mq_request_started(rq)) {
754 WRITE_ONCE(rq->state, MQ_RQ_IDLE);
755 rq->rq_flags &= ~RQF_TIMED_OUT;
759 void blk_mq_requeue_request(struct request *rq, bool kick_requeue_list)
761 __blk_mq_requeue_request(rq);
763 /* this request will be re-inserted to io scheduler queue */
764 blk_mq_sched_requeue_request(rq);
766 blk_mq_add_to_requeue_list(rq, true, kick_requeue_list);
768 EXPORT_SYMBOL(blk_mq_requeue_request);
770 static void blk_mq_requeue_work(struct work_struct *work)
772 struct request_queue *q =
773 container_of(work, struct request_queue, requeue_work.work);
775 struct request *rq, *next;
777 spin_lock_irq(&q->requeue_lock);
778 list_splice_init(&q->requeue_list, &rq_list);
779 spin_unlock_irq(&q->requeue_lock);
781 list_for_each_entry_safe(rq, next, &rq_list, queuelist) {
782 if (!(rq->rq_flags & (RQF_SOFTBARRIER | RQF_DONTPREP)))
785 rq->rq_flags &= ~RQF_SOFTBARRIER;
786 list_del_init(&rq->queuelist);
788 * If RQF_DONTPREP, rq has contained some driver specific
789 * data, so insert it to hctx dispatch list to avoid any
792 if (rq->rq_flags & RQF_DONTPREP)
793 blk_mq_request_bypass_insert(rq, false, false);
795 blk_mq_sched_insert_request(rq, true, false, false);
798 while (!list_empty(&rq_list)) {
799 rq = list_entry(rq_list.next, struct request, queuelist);
800 list_del_init(&rq->queuelist);
801 blk_mq_sched_insert_request(rq, false, false, false);
804 blk_mq_run_hw_queues(q, false);
807 void blk_mq_add_to_requeue_list(struct request *rq, bool at_head,
808 bool kick_requeue_list)
810 struct request_queue *q = rq->q;
814 * We abuse this flag that is otherwise used by the I/O scheduler to
815 * request head insertion from the workqueue.
817 BUG_ON(rq->rq_flags & RQF_SOFTBARRIER);
819 spin_lock_irqsave(&q->requeue_lock, flags);
821 rq->rq_flags |= RQF_SOFTBARRIER;
822 list_add(&rq->queuelist, &q->requeue_list);
824 list_add_tail(&rq->queuelist, &q->requeue_list);
826 spin_unlock_irqrestore(&q->requeue_lock, flags);
828 if (kick_requeue_list)
829 blk_mq_kick_requeue_list(q);
832 void blk_mq_kick_requeue_list(struct request_queue *q)
834 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND, &q->requeue_work, 0);
836 EXPORT_SYMBOL(blk_mq_kick_requeue_list);
838 void blk_mq_delay_kick_requeue_list(struct request_queue *q,
841 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND, &q->requeue_work,
842 msecs_to_jiffies(msecs));
844 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list);
846 struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
848 if (tag < tags->nr_tags) {
849 prefetch(tags->rqs[tag]);
850 return tags->rqs[tag];
855 EXPORT_SYMBOL(blk_mq_tag_to_rq);
857 static bool blk_mq_rq_inflight(struct blk_mq_hw_ctx *hctx, struct request *rq,
858 void *priv, bool reserved)
861 * If we find a request that isn't idle and the queue matches,
862 * we know the queue is busy. Return false to stop the iteration.
864 if (blk_mq_request_started(rq) && rq->q == hctx->queue) {
874 bool blk_mq_queue_inflight(struct request_queue *q)
878 blk_mq_queue_tag_busy_iter(q, blk_mq_rq_inflight, &busy);
881 EXPORT_SYMBOL_GPL(blk_mq_queue_inflight);
883 static void blk_mq_rq_timed_out(struct request *req, bool reserved)
885 req->rq_flags |= RQF_TIMED_OUT;
886 if (req->q->mq_ops->timeout) {
887 enum blk_eh_timer_return ret;
889 ret = req->q->mq_ops->timeout(req, reserved);
890 if (ret == BLK_EH_DONE)
892 WARN_ON_ONCE(ret != BLK_EH_RESET_TIMER);
898 static bool blk_mq_req_expired(struct request *rq, unsigned long *next)
900 unsigned long deadline;
902 if (blk_mq_rq_state(rq) != MQ_RQ_IN_FLIGHT)
904 if (rq->rq_flags & RQF_TIMED_OUT)
907 deadline = READ_ONCE(rq->deadline);
908 if (time_after_eq(jiffies, deadline))
913 else if (time_after(*next, deadline))
918 void blk_mq_put_rq_ref(struct request *rq)
922 else if (refcount_dec_and_test(&rq->ref))
923 __blk_mq_free_request(rq);
926 static bool blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
927 struct request *rq, void *priv, bool reserved)
929 unsigned long *next = priv;
932 * blk_mq_queue_tag_busy_iter() has locked the request, so it cannot
933 * be reallocated underneath the timeout handler's processing, then
934 * the expire check is reliable. If the request is not expired, then
935 * it was completed and reallocated as a new request after returning
936 * from blk_mq_check_expired().
938 if (blk_mq_req_expired(rq, next))
939 blk_mq_rq_timed_out(rq, reserved);
943 static void blk_mq_timeout_work(struct work_struct *work)
945 struct request_queue *q =
946 container_of(work, struct request_queue, timeout_work);
947 unsigned long next = 0;
948 struct blk_mq_hw_ctx *hctx;
951 /* A deadlock might occur if a request is stuck requiring a
952 * timeout at the same time a queue freeze is waiting
953 * completion, since the timeout code would not be able to
954 * acquire the queue reference here.
956 * That's why we don't use blk_queue_enter here; instead, we use
957 * percpu_ref_tryget directly, because we need to be able to
958 * obtain a reference even in the short window between the queue
959 * starting to freeze, by dropping the first reference in
960 * blk_freeze_queue_start, and the moment the last request is
961 * consumed, marked by the instant q_usage_counter reaches
964 if (!percpu_ref_tryget(&q->q_usage_counter))
967 blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &next);
970 mod_timer(&q->timeout, next);
973 * Request timeouts are handled as a forward rolling timer. If
974 * we end up here it means that no requests are pending and
975 * also that no request has been pending for a while. Mark
978 queue_for_each_hw_ctx(q, hctx, i) {
979 /* the hctx may be unmapped, so check it here */
980 if (blk_mq_hw_queue_mapped(hctx))
981 blk_mq_tag_idle(hctx);
987 struct flush_busy_ctx_data {
988 struct blk_mq_hw_ctx *hctx;
989 struct list_head *list;
992 static bool flush_busy_ctx(struct sbitmap *sb, unsigned int bitnr, void *data)
994 struct flush_busy_ctx_data *flush_data = data;
995 struct blk_mq_hw_ctx *hctx = flush_data->hctx;
996 struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
997 enum hctx_type type = hctx->type;
999 spin_lock(&ctx->lock);
1000 list_splice_tail_init(&ctx->rq_lists[type], flush_data->list);
1001 sbitmap_clear_bit(sb, bitnr);
1002 spin_unlock(&ctx->lock);
1007 * Process software queues that have been marked busy, splicing them
1008 * to the for-dispatch
1010 void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list)
1012 struct flush_busy_ctx_data data = {
1017 sbitmap_for_each_set(&hctx->ctx_map, flush_busy_ctx, &data);
1019 EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs);
1021 struct dispatch_rq_data {
1022 struct blk_mq_hw_ctx *hctx;
1026 static bool dispatch_rq_from_ctx(struct sbitmap *sb, unsigned int bitnr,
1029 struct dispatch_rq_data *dispatch_data = data;
1030 struct blk_mq_hw_ctx *hctx = dispatch_data->hctx;
1031 struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
1032 enum hctx_type type = hctx->type;
1034 spin_lock(&ctx->lock);
1035 if (!list_empty(&ctx->rq_lists[type])) {
1036 dispatch_data->rq = list_entry_rq(ctx->rq_lists[type].next);
1037 list_del_init(&dispatch_data->rq->queuelist);
1038 if (list_empty(&ctx->rq_lists[type]))
1039 sbitmap_clear_bit(sb, bitnr);
1041 spin_unlock(&ctx->lock);
1043 return !dispatch_data->rq;
1046 struct request *blk_mq_dequeue_from_ctx(struct blk_mq_hw_ctx *hctx,
1047 struct blk_mq_ctx *start)
1049 unsigned off = start ? start->index_hw[hctx->type] : 0;
1050 struct dispatch_rq_data data = {
1055 __sbitmap_for_each_set(&hctx->ctx_map, off,
1056 dispatch_rq_from_ctx, &data);
1061 static inline unsigned int queued_to_index(unsigned int queued)
1066 return min(BLK_MQ_MAX_DISPATCH_ORDER - 1, ilog2(queued) + 1);
1069 static bool __blk_mq_get_driver_tag(struct request *rq)
1071 struct sbitmap_queue *bt = rq->mq_hctx->tags->bitmap_tags;
1072 unsigned int tag_offset = rq->mq_hctx->tags->nr_reserved_tags;
1075 blk_mq_tag_busy(rq->mq_hctx);
1077 if (blk_mq_tag_is_reserved(rq->mq_hctx->sched_tags, rq->internal_tag)) {
1078 bt = rq->mq_hctx->tags->breserved_tags;
1081 if (!hctx_may_queue(rq->mq_hctx, bt))
1085 tag = __sbitmap_queue_get(bt);
1086 if (tag == BLK_MQ_NO_TAG)
1089 rq->tag = tag + tag_offset;
1093 bool blk_mq_get_driver_tag(struct request *rq)
1095 struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
1097 if (rq->tag == BLK_MQ_NO_TAG && !__blk_mq_get_driver_tag(rq))
1100 if ((hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED) &&
1101 !(rq->rq_flags & RQF_MQ_INFLIGHT)) {
1102 rq->rq_flags |= RQF_MQ_INFLIGHT;
1103 __blk_mq_inc_active_requests(hctx);
1105 hctx->tags->rqs[rq->tag] = rq;
1109 static int blk_mq_dispatch_wake(wait_queue_entry_t *wait, unsigned mode,
1110 int flags, void *key)
1112 struct blk_mq_hw_ctx *hctx;
1114 hctx = container_of(wait, struct blk_mq_hw_ctx, dispatch_wait);
1116 spin_lock(&hctx->dispatch_wait_lock);
1117 if (!list_empty(&wait->entry)) {
1118 struct sbitmap_queue *sbq;
1120 list_del_init(&wait->entry);
1121 sbq = hctx->tags->bitmap_tags;
1122 atomic_dec(&sbq->ws_active);
1124 spin_unlock(&hctx->dispatch_wait_lock);
1126 blk_mq_run_hw_queue(hctx, true);
1131 * Mark us waiting for a tag. For shared tags, this involves hooking us into
1132 * the tag wakeups. For non-shared tags, we can simply mark us needing a
1133 * restart. For both cases, take care to check the condition again after
1134 * marking us as waiting.
1136 static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx *hctx,
1139 struct sbitmap_queue *sbq = hctx->tags->bitmap_tags;
1140 struct wait_queue_head *wq;
1141 wait_queue_entry_t *wait;
1144 if (!(hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED)) {
1145 blk_mq_sched_mark_restart_hctx(hctx);
1148 * It's possible that a tag was freed in the window between the
1149 * allocation failure and adding the hardware queue to the wait
1152 * Don't clear RESTART here, someone else could have set it.
1153 * At most this will cost an extra queue run.
1155 return blk_mq_get_driver_tag(rq);
1158 wait = &hctx->dispatch_wait;
1159 if (!list_empty_careful(&wait->entry))
1162 wq = &bt_wait_ptr(sbq, hctx)->wait;
1164 spin_lock_irq(&wq->lock);
1165 spin_lock(&hctx->dispatch_wait_lock);
1166 if (!list_empty(&wait->entry)) {
1167 spin_unlock(&hctx->dispatch_wait_lock);
1168 spin_unlock_irq(&wq->lock);
1172 atomic_inc(&sbq->ws_active);
1173 wait->flags &= ~WQ_FLAG_EXCLUSIVE;
1174 __add_wait_queue(wq, wait);
1177 * It's possible that a tag was freed in the window between the
1178 * allocation failure and adding the hardware queue to the wait
1181 ret = blk_mq_get_driver_tag(rq);
1183 spin_unlock(&hctx->dispatch_wait_lock);
1184 spin_unlock_irq(&wq->lock);
1189 * We got a tag, remove ourselves from the wait queue to ensure
1190 * someone else gets the wakeup.
1192 list_del_init(&wait->entry);
1193 atomic_dec(&sbq->ws_active);
1194 spin_unlock(&hctx->dispatch_wait_lock);
1195 spin_unlock_irq(&wq->lock);
1200 #define BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT 8
1201 #define BLK_MQ_DISPATCH_BUSY_EWMA_FACTOR 4
1203 * Update dispatch busy with the Exponential Weighted Moving Average(EWMA):
1204 * - EWMA is one simple way to compute running average value
1205 * - weight(7/8 and 1/8) is applied so that it can decrease exponentially
1206 * - take 4 as factor for avoiding to get too small(0) result, and this
1207 * factor doesn't matter because EWMA decreases exponentially
1209 static void blk_mq_update_dispatch_busy(struct blk_mq_hw_ctx *hctx, bool busy)
1213 ewma = hctx->dispatch_busy;
1218 ewma *= BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT - 1;
1220 ewma += 1 << BLK_MQ_DISPATCH_BUSY_EWMA_FACTOR;
1221 ewma /= BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT;
1223 hctx->dispatch_busy = ewma;
1226 #define BLK_MQ_RESOURCE_DELAY 3 /* ms units */
1228 static void blk_mq_handle_dev_resource(struct request *rq,
1229 struct list_head *list)
1231 struct request *next =
1232 list_first_entry_or_null(list, struct request, queuelist);
1235 * If an I/O scheduler has been configured and we got a driver tag for
1236 * the next request already, free it.
1239 blk_mq_put_driver_tag(next);
1241 list_add(&rq->queuelist, list);
1242 __blk_mq_requeue_request(rq);
1245 static void blk_mq_handle_zone_resource(struct request *rq,
1246 struct list_head *zone_list)
1249 * If we end up here it is because we cannot dispatch a request to a
1250 * specific zone due to LLD level zone-write locking or other zone
1251 * related resource not being available. In this case, set the request
1252 * aside in zone_list for retrying it later.
1254 list_add(&rq->queuelist, zone_list);
1255 __blk_mq_requeue_request(rq);
1258 enum prep_dispatch {
1260 PREP_DISPATCH_NO_TAG,
1261 PREP_DISPATCH_NO_BUDGET,
1264 static enum prep_dispatch blk_mq_prep_dispatch_rq(struct request *rq,
1267 struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
1268 int budget_token = -1;
1271 budget_token = blk_mq_get_dispatch_budget(rq->q);
1272 if (budget_token < 0) {
1273 blk_mq_put_driver_tag(rq);
1274 return PREP_DISPATCH_NO_BUDGET;
1276 blk_mq_set_rq_budget_token(rq, budget_token);
1279 if (!blk_mq_get_driver_tag(rq)) {
1281 * The initial allocation attempt failed, so we need to
1282 * rerun the hardware queue when a tag is freed. The
1283 * waitqueue takes care of that. If the queue is run
1284 * before we add this entry back on the dispatch list,
1285 * we'll re-run it below.
1287 if (!blk_mq_mark_tag_wait(hctx, rq)) {
1289 * All budgets not got from this function will be put
1290 * together during handling partial dispatch
1293 blk_mq_put_dispatch_budget(rq->q, budget_token);
1294 return PREP_DISPATCH_NO_TAG;
1298 return PREP_DISPATCH_OK;
1301 /* release all allocated budgets before calling to blk_mq_dispatch_rq_list */
1302 static void blk_mq_release_budgets(struct request_queue *q,
1303 struct list_head *list)
1307 list_for_each_entry(rq, list, queuelist) {
1308 int budget_token = blk_mq_get_rq_budget_token(rq);
1310 if (budget_token >= 0)
1311 blk_mq_put_dispatch_budget(q, budget_token);
1316 * Returns true if we did some work AND can potentially do more.
1318 bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list,
1319 unsigned int nr_budgets)
1321 enum prep_dispatch prep;
1322 struct request_queue *q = hctx->queue;
1323 struct request *rq, *nxt;
1325 blk_status_t ret = BLK_STS_OK;
1326 LIST_HEAD(zone_list);
1327 bool needs_resource = false;
1329 if (list_empty(list))
1333 * Now process all the entries, sending them to the driver.
1335 errors = queued = 0;
1337 struct blk_mq_queue_data bd;
1339 rq = list_first_entry(list, struct request, queuelist);
1341 WARN_ON_ONCE(hctx != rq->mq_hctx);
1342 prep = blk_mq_prep_dispatch_rq(rq, !nr_budgets);
1343 if (prep != PREP_DISPATCH_OK)
1346 list_del_init(&rq->queuelist);
1351 * Flag last if we have no more requests, or if we have more
1352 * but can't assign a driver tag to it.
1354 if (list_empty(list))
1357 nxt = list_first_entry(list, struct request, queuelist);
1358 bd.last = !blk_mq_get_driver_tag(nxt);
1362 * once the request is queued to lld, no need to cover the
1367 ret = q->mq_ops->queue_rq(hctx, &bd);
1372 case BLK_STS_RESOURCE:
1373 needs_resource = true;
1375 case BLK_STS_DEV_RESOURCE:
1376 blk_mq_handle_dev_resource(rq, list);
1378 case BLK_STS_ZONE_RESOURCE:
1380 * Move the request to zone_list and keep going through
1381 * the dispatch list to find more requests the drive can
1384 blk_mq_handle_zone_resource(rq, &zone_list);
1385 needs_resource = true;
1389 blk_mq_end_request(rq, ret);
1391 } while (!list_empty(list));
1393 if (!list_empty(&zone_list))
1394 list_splice_tail_init(&zone_list, list);
1396 hctx->dispatched[queued_to_index(queued)]++;
1398 /* If we didn't flush the entire list, we could have told the driver
1399 * there was more coming, but that turned out to be a lie.
1401 if ((!list_empty(list) || errors) && q->mq_ops->commit_rqs && queued)
1402 q->mq_ops->commit_rqs(hctx);
1404 * Any items that need requeuing? Stuff them into hctx->dispatch,
1405 * that is where we will continue on next queue run.
1407 if (!list_empty(list)) {
1409 /* For non-shared tags, the RESTART check will suffice */
1410 bool no_tag = prep == PREP_DISPATCH_NO_TAG &&
1411 (hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED);
1414 blk_mq_release_budgets(q, list);
1416 spin_lock(&hctx->lock);
1417 list_splice_tail_init(list, &hctx->dispatch);
1418 spin_unlock(&hctx->lock);
1421 * Order adding requests to hctx->dispatch and checking
1422 * SCHED_RESTART flag. The pair of this smp_mb() is the one
1423 * in blk_mq_sched_restart(). Avoid restart code path to
1424 * miss the new added requests to hctx->dispatch, meantime
1425 * SCHED_RESTART is observed here.
1430 * If SCHED_RESTART was set by the caller of this function and
1431 * it is no longer set that means that it was cleared by another
1432 * thread and hence that a queue rerun is needed.
1434 * If 'no_tag' is set, that means that we failed getting
1435 * a driver tag with an I/O scheduler attached. If our dispatch
1436 * waitqueue is no longer active, ensure that we run the queue
1437 * AFTER adding our entries back to the list.
1439 * If no I/O scheduler has been configured it is possible that
1440 * the hardware queue got stopped and restarted before requests
1441 * were pushed back onto the dispatch list. Rerun the queue to
1442 * avoid starvation. Notes:
1443 * - blk_mq_run_hw_queue() checks whether or not a queue has
1444 * been stopped before rerunning a queue.
1445 * - Some but not all block drivers stop a queue before
1446 * returning BLK_STS_RESOURCE. Two exceptions are scsi-mq
1449 * If driver returns BLK_STS_RESOURCE and SCHED_RESTART
1450 * bit is set, run queue after a delay to avoid IO stalls
1451 * that could otherwise occur if the queue is idle. We'll do
1452 * similar if we couldn't get budget or couldn't lock a zone
1453 * and SCHED_RESTART is set.
1455 needs_restart = blk_mq_sched_needs_restart(hctx);
1456 if (prep == PREP_DISPATCH_NO_BUDGET)
1457 needs_resource = true;
1458 if (!needs_restart ||
1459 (no_tag && list_empty_careful(&hctx->dispatch_wait.entry)))
1460 blk_mq_run_hw_queue(hctx, true);
1461 else if (needs_restart && needs_resource)
1462 blk_mq_delay_run_hw_queue(hctx, BLK_MQ_RESOURCE_DELAY);
1464 blk_mq_update_dispatch_busy(hctx, true);
1467 blk_mq_update_dispatch_busy(hctx, false);
1469 return (queued + errors) != 0;
1473 * __blk_mq_run_hw_queue - Run a hardware queue.
1474 * @hctx: Pointer to the hardware queue to run.
1476 * Send pending requests to the hardware.
1478 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
1483 * We can't run the queue inline with ints disabled. Ensure that
1484 * we catch bad users of this early.
1486 WARN_ON_ONCE(in_interrupt());
1488 might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
1490 hctx_lock(hctx, &srcu_idx);
1491 blk_mq_sched_dispatch_requests(hctx);
1492 hctx_unlock(hctx, srcu_idx);
1495 static inline int blk_mq_first_mapped_cpu(struct blk_mq_hw_ctx *hctx)
1497 int cpu = cpumask_first_and(hctx->cpumask, cpu_online_mask);
1499 if (cpu >= nr_cpu_ids)
1500 cpu = cpumask_first(hctx->cpumask);
1505 * It'd be great if the workqueue API had a way to pass
1506 * in a mask and had some smarts for more clever placement.
1507 * For now we just round-robin here, switching for every
1508 * BLK_MQ_CPU_WORK_BATCH queued items.
1510 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
1513 int next_cpu = hctx->next_cpu;
1515 if (hctx->queue->nr_hw_queues == 1)
1516 return WORK_CPU_UNBOUND;
1518 if (--hctx->next_cpu_batch <= 0) {
1520 next_cpu = cpumask_next_and(next_cpu, hctx->cpumask,
1522 if (next_cpu >= nr_cpu_ids)
1523 next_cpu = blk_mq_first_mapped_cpu(hctx);
1524 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
1528 * Do unbound schedule if we can't find a online CPU for this hctx,
1529 * and it should only happen in the path of handling CPU DEAD.
1531 if (!cpu_online(next_cpu)) {
1538 * Make sure to re-select CPU next time once after CPUs
1539 * in hctx->cpumask become online again.
1541 hctx->next_cpu = next_cpu;
1542 hctx->next_cpu_batch = 1;
1543 return WORK_CPU_UNBOUND;
1546 hctx->next_cpu = next_cpu;
1551 * __blk_mq_delay_run_hw_queue - Run (or schedule to run) a hardware queue.
1552 * @hctx: Pointer to the hardware queue to run.
1553 * @async: If we want to run the queue asynchronously.
1554 * @msecs: Milliseconds of delay to wait before running the queue.
1556 * If !@async, try to run the queue now. Else, run the queue asynchronously and
1557 * with a delay of @msecs.
1559 static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async,
1560 unsigned long msecs)
1562 if (unlikely(blk_mq_hctx_stopped(hctx)))
1565 if (!async && !(hctx->flags & BLK_MQ_F_BLOCKING)) {
1566 int cpu = get_cpu();
1567 if (cpumask_test_cpu(cpu, hctx->cpumask)) {
1568 __blk_mq_run_hw_queue(hctx);
1576 kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx), &hctx->run_work,
1577 msecs_to_jiffies(msecs));
1581 * blk_mq_delay_run_hw_queue - Run a hardware queue asynchronously.
1582 * @hctx: Pointer to the hardware queue to run.
1583 * @msecs: Milliseconds of delay to wait before running the queue.
1585 * Run a hardware queue asynchronously with a delay of @msecs.
1587 void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
1589 __blk_mq_delay_run_hw_queue(hctx, true, msecs);
1591 EXPORT_SYMBOL(blk_mq_delay_run_hw_queue);
1594 * blk_mq_run_hw_queue - Start to run a hardware queue.
1595 * @hctx: Pointer to the hardware queue to run.
1596 * @async: If we want to run the queue asynchronously.
1598 * Check if the request queue is not in a quiesced state and if there are
1599 * pending requests to be sent. If this is true, run the queue to send requests
1602 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
1608 * When queue is quiesced, we may be switching io scheduler, or
1609 * updating nr_hw_queues, or other things, and we can't run queue
1610 * any more, even __blk_mq_hctx_has_pending() can't be called safely.
1612 * And queue will be rerun in blk_mq_unquiesce_queue() if it is
1615 hctx_lock(hctx, &srcu_idx);
1616 need_run = !blk_queue_quiesced(hctx->queue) &&
1617 blk_mq_hctx_has_pending(hctx);
1618 hctx_unlock(hctx, srcu_idx);
1621 __blk_mq_delay_run_hw_queue(hctx, async, 0);
1623 EXPORT_SYMBOL(blk_mq_run_hw_queue);
1626 * Is the request queue handled by an IO scheduler that does not respect
1627 * hardware queues when dispatching?
1629 static bool blk_mq_has_sqsched(struct request_queue *q)
1631 struct elevator_queue *e = q->elevator;
1633 if (e && e->type->ops.dispatch_request &&
1634 !(e->type->elevator_features & ELEVATOR_F_MQ_AWARE))
1640 * Return prefered queue to dispatch from (if any) for non-mq aware IO
1643 static struct blk_mq_hw_ctx *blk_mq_get_sq_hctx(struct request_queue *q)
1645 struct blk_mq_ctx *ctx = blk_mq_get_ctx(q);
1647 * If the IO scheduler does not respect hardware queues when
1648 * dispatching, we just don't bother with multiple HW queues and
1649 * dispatch from hctx for the current CPU since running multiple queues
1650 * just causes lock contention inside the scheduler and pointless cache
1653 struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, 0, ctx);
1655 if (!blk_mq_hctx_stopped(hctx))
1661 * blk_mq_run_hw_queues - Run all hardware queues in a request queue.
1662 * @q: Pointer to the request queue to run.
1663 * @async: If we want to run the queue asynchronously.
1665 void blk_mq_run_hw_queues(struct request_queue *q, bool async)
1667 struct blk_mq_hw_ctx *hctx, *sq_hctx;
1671 if (blk_mq_has_sqsched(q))
1672 sq_hctx = blk_mq_get_sq_hctx(q);
1673 queue_for_each_hw_ctx(q, hctx, i) {
1674 if (blk_mq_hctx_stopped(hctx))
1677 * Dispatch from this hctx either if there's no hctx preferred
1678 * by IO scheduler or if it has requests that bypass the
1681 if (!sq_hctx || sq_hctx == hctx ||
1682 !list_empty_careful(&hctx->dispatch))
1683 blk_mq_run_hw_queue(hctx, async);
1686 EXPORT_SYMBOL(blk_mq_run_hw_queues);
1689 * blk_mq_delay_run_hw_queues - Run all hardware queues asynchronously.
1690 * @q: Pointer to the request queue to run.
1691 * @msecs: Milliseconds of delay to wait before running the queues.
1693 void blk_mq_delay_run_hw_queues(struct request_queue *q, unsigned long msecs)
1695 struct blk_mq_hw_ctx *hctx, *sq_hctx;
1699 if (blk_mq_has_sqsched(q))
1700 sq_hctx = blk_mq_get_sq_hctx(q);
1701 queue_for_each_hw_ctx(q, hctx, i) {
1702 if (blk_mq_hctx_stopped(hctx))
1705 * Dispatch from this hctx either if there's no hctx preferred
1706 * by IO scheduler or if it has requests that bypass the
1709 if (!sq_hctx || sq_hctx == hctx ||
1710 !list_empty_careful(&hctx->dispatch))
1711 blk_mq_delay_run_hw_queue(hctx, msecs);
1714 EXPORT_SYMBOL(blk_mq_delay_run_hw_queues);
1717 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1718 * @q: request queue.
1720 * The caller is responsible for serializing this function against
1721 * blk_mq_{start,stop}_hw_queue().
1723 bool blk_mq_queue_stopped(struct request_queue *q)
1725 struct blk_mq_hw_ctx *hctx;
1728 queue_for_each_hw_ctx(q, hctx, i)
1729 if (blk_mq_hctx_stopped(hctx))
1734 EXPORT_SYMBOL(blk_mq_queue_stopped);
1737 * This function is often used for pausing .queue_rq() by driver when
1738 * there isn't enough resource or some conditions aren't satisfied, and
1739 * BLK_STS_RESOURCE is usually returned.
1741 * We do not guarantee that dispatch can be drained or blocked
1742 * after blk_mq_stop_hw_queue() returns. Please use
1743 * blk_mq_quiesce_queue() for that requirement.
1745 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
1747 cancel_delayed_work(&hctx->run_work);
1749 set_bit(BLK_MQ_S_STOPPED, &hctx->state);
1751 EXPORT_SYMBOL(blk_mq_stop_hw_queue);
1754 * This function is often used for pausing .queue_rq() by driver when
1755 * there isn't enough resource or some conditions aren't satisfied, and
1756 * BLK_STS_RESOURCE is usually returned.
1758 * We do not guarantee that dispatch can be drained or blocked
1759 * after blk_mq_stop_hw_queues() returns. Please use
1760 * blk_mq_quiesce_queue() for that requirement.
1762 void blk_mq_stop_hw_queues(struct request_queue *q)
1764 struct blk_mq_hw_ctx *hctx;
1767 queue_for_each_hw_ctx(q, hctx, i)
1768 blk_mq_stop_hw_queue(hctx);
1770 EXPORT_SYMBOL(blk_mq_stop_hw_queues);
1772 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
1774 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1776 blk_mq_run_hw_queue(hctx, false);
1778 EXPORT_SYMBOL(blk_mq_start_hw_queue);
1780 void blk_mq_start_hw_queues(struct request_queue *q)
1782 struct blk_mq_hw_ctx *hctx;
1785 queue_for_each_hw_ctx(q, hctx, i)
1786 blk_mq_start_hw_queue(hctx);
1788 EXPORT_SYMBOL(blk_mq_start_hw_queues);
1790 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
1792 if (!blk_mq_hctx_stopped(hctx))
1795 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1796 blk_mq_run_hw_queue(hctx, async);
1798 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue);
1800 void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async)
1802 struct blk_mq_hw_ctx *hctx;
1805 queue_for_each_hw_ctx(q, hctx, i)
1806 blk_mq_start_stopped_hw_queue(hctx, async);
1808 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);
1810 static void blk_mq_run_work_fn(struct work_struct *work)
1812 struct blk_mq_hw_ctx *hctx;
1814 hctx = container_of(work, struct blk_mq_hw_ctx, run_work.work);
1817 * If we are stopped, don't run the queue.
1819 if (blk_mq_hctx_stopped(hctx))
1822 __blk_mq_run_hw_queue(hctx);
1825 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx,
1829 struct blk_mq_ctx *ctx = rq->mq_ctx;
1830 enum hctx_type type = hctx->type;
1832 lockdep_assert_held(&ctx->lock);
1834 trace_block_rq_insert(rq);
1837 list_add(&rq->queuelist, &ctx->rq_lists[type]);
1839 list_add_tail(&rq->queuelist, &ctx->rq_lists[type]);
1842 void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
1845 struct blk_mq_ctx *ctx = rq->mq_ctx;
1847 lockdep_assert_held(&ctx->lock);
1849 __blk_mq_insert_req_list(hctx, rq, at_head);
1850 blk_mq_hctx_mark_pending(hctx, ctx);
1854 * blk_mq_request_bypass_insert - Insert a request at dispatch list.
1855 * @rq: Pointer to request to be inserted.
1856 * @at_head: true if the request should be inserted at the head of the list.
1857 * @run_queue: If we should run the hardware queue after inserting the request.
1859 * Should only be used carefully, when the caller knows we want to
1860 * bypass a potential IO scheduler on the target device.
1862 void blk_mq_request_bypass_insert(struct request *rq, bool at_head,
1865 struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
1867 spin_lock(&hctx->lock);
1869 list_add(&rq->queuelist, &hctx->dispatch);
1871 list_add_tail(&rq->queuelist, &hctx->dispatch);
1872 spin_unlock(&hctx->lock);
1875 blk_mq_run_hw_queue(hctx, false);
1878 void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
1879 struct list_head *list)
1883 enum hctx_type type = hctx->type;
1886 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1889 list_for_each_entry(rq, list, queuelist) {
1890 BUG_ON(rq->mq_ctx != ctx);
1891 trace_block_rq_insert(rq);
1894 spin_lock(&ctx->lock);
1895 list_splice_tail_init(list, &ctx->rq_lists[type]);
1896 blk_mq_hctx_mark_pending(hctx, ctx);
1897 spin_unlock(&ctx->lock);
1900 static int plug_rq_cmp(void *priv, const struct list_head *a,
1901 const struct list_head *b)
1903 struct request *rqa = container_of(a, struct request, queuelist);
1904 struct request *rqb = container_of(b, struct request, queuelist);
1906 if (rqa->mq_ctx != rqb->mq_ctx)
1907 return rqa->mq_ctx > rqb->mq_ctx;
1908 if (rqa->mq_hctx != rqb->mq_hctx)
1909 return rqa->mq_hctx > rqb->mq_hctx;
1911 return blk_rq_pos(rqa) > blk_rq_pos(rqb);
1914 void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
1918 if (list_empty(&plug->mq_list))
1920 list_splice_init(&plug->mq_list, &list);
1922 if (plug->rq_count > 2 && plug->multiple_queues)
1923 list_sort(NULL, &list, plug_rq_cmp);
1928 struct list_head rq_list;
1929 struct request *rq, *head_rq = list_entry_rq(list.next);
1930 struct list_head *pos = &head_rq->queuelist; /* skip first */
1931 struct blk_mq_hw_ctx *this_hctx = head_rq->mq_hctx;
1932 struct blk_mq_ctx *this_ctx = head_rq->mq_ctx;
1933 unsigned int depth = 1;
1935 list_for_each_continue(pos, &list) {
1936 rq = list_entry_rq(pos);
1938 if (rq->mq_hctx != this_hctx || rq->mq_ctx != this_ctx)
1943 list_cut_before(&rq_list, &list, pos);
1944 trace_block_unplug(head_rq->q, depth, !from_schedule);
1945 blk_mq_sched_insert_requests(this_hctx, this_ctx, &rq_list,
1947 } while(!list_empty(&list));
1950 static void blk_mq_bio_to_request(struct request *rq, struct bio *bio,
1951 unsigned int nr_segs)
1955 if (bio->bi_opf & REQ_RAHEAD)
1956 rq->cmd_flags |= REQ_FAILFAST_MASK;
1958 rq->__sector = bio->bi_iter.bi_sector;
1959 rq->write_hint = bio->bi_write_hint;
1960 blk_rq_bio_prep(rq, bio, nr_segs);
1962 /* This can't fail, since GFP_NOIO includes __GFP_DIRECT_RECLAIM. */
1963 err = blk_crypto_rq_bio_prep(rq, bio, GFP_NOIO);
1966 blk_account_io_start(rq);
1969 static blk_status_t __blk_mq_issue_directly(struct blk_mq_hw_ctx *hctx,
1971 blk_qc_t *cookie, bool last)
1973 struct request_queue *q = rq->q;
1974 struct blk_mq_queue_data bd = {
1978 blk_qc_t new_cookie;
1981 new_cookie = request_to_qc_t(hctx, rq);
1984 * For OK queue, we are done. For error, caller may kill it.
1985 * Any other error (busy), just add it to our list as we
1986 * previously would have done.
1988 ret = q->mq_ops->queue_rq(hctx, &bd);
1991 blk_mq_update_dispatch_busy(hctx, false);
1992 *cookie = new_cookie;
1994 case BLK_STS_RESOURCE:
1995 case BLK_STS_DEV_RESOURCE:
1996 blk_mq_update_dispatch_busy(hctx, true);
1997 __blk_mq_requeue_request(rq);
2000 blk_mq_update_dispatch_busy(hctx, false);
2001 *cookie = BLK_QC_T_NONE;
2008 static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
2011 bool bypass_insert, bool last)
2013 struct request_queue *q = rq->q;
2014 bool run_queue = true;
2018 * RCU or SRCU read lock is needed before checking quiesced flag.
2020 * When queue is stopped or quiesced, ignore 'bypass_insert' from
2021 * blk_mq_request_issue_directly(), and return BLK_STS_OK to caller,
2022 * and avoid driver to try to dispatch again.
2024 if (blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q)) {
2026 bypass_insert = false;
2030 if (q->elevator && !bypass_insert)
2033 budget_token = blk_mq_get_dispatch_budget(q);
2034 if (budget_token < 0)
2037 blk_mq_set_rq_budget_token(rq, budget_token);
2039 if (!blk_mq_get_driver_tag(rq)) {
2040 blk_mq_put_dispatch_budget(q, budget_token);
2044 return __blk_mq_issue_directly(hctx, rq, cookie, last);
2047 return BLK_STS_RESOURCE;
2049 blk_mq_sched_insert_request(rq, false, run_queue, false);
2055 * blk_mq_try_issue_directly - Try to send a request directly to device driver.
2056 * @hctx: Pointer of the associated hardware queue.
2057 * @rq: Pointer to request to be sent.
2058 * @cookie: Request queue cookie.
2060 * If the device has enough resources to accept a new request now, send the
2061 * request directly to device driver. Else, insert at hctx->dispatch queue, so
2062 * we can try send it another time in the future. Requests inserted at this
2063 * queue have higher priority.
2065 static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
2066 struct request *rq, blk_qc_t *cookie)
2071 might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
2073 hctx_lock(hctx, &srcu_idx);
2075 ret = __blk_mq_try_issue_directly(hctx, rq, cookie, false, true);
2076 if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE)
2077 blk_mq_request_bypass_insert(rq, false, true);
2078 else if (ret != BLK_STS_OK)
2079 blk_mq_end_request(rq, ret);
2081 hctx_unlock(hctx, srcu_idx);
2084 blk_status_t blk_mq_request_issue_directly(struct request *rq, bool last)
2088 blk_qc_t unused_cookie;
2089 struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
2091 hctx_lock(hctx, &srcu_idx);
2092 ret = __blk_mq_try_issue_directly(hctx, rq, &unused_cookie, true, last);
2093 hctx_unlock(hctx, srcu_idx);
2098 void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx,
2099 struct list_head *list)
2104 while (!list_empty(list)) {
2106 struct request *rq = list_first_entry(list, struct request,
2109 list_del_init(&rq->queuelist);
2110 ret = blk_mq_request_issue_directly(rq, list_empty(list));
2111 if (ret != BLK_STS_OK) {
2112 if (ret == BLK_STS_RESOURCE ||
2113 ret == BLK_STS_DEV_RESOURCE) {
2114 blk_mq_request_bypass_insert(rq, false,
2118 blk_mq_end_request(rq, ret);
2125 * If we didn't flush the entire list, we could have told
2126 * the driver there was more coming, but that turned out to
2129 if ((!list_empty(list) || errors) &&
2130 hctx->queue->mq_ops->commit_rqs && queued)
2131 hctx->queue->mq_ops->commit_rqs(hctx);
2134 static void blk_add_rq_to_plug(struct blk_plug *plug, struct request *rq)
2136 list_add_tail(&rq->queuelist, &plug->mq_list);
2138 if (!plug->multiple_queues && !list_is_singular(&plug->mq_list)) {
2139 struct request *tmp;
2141 tmp = list_first_entry(&plug->mq_list, struct request,
2143 if (tmp->q != rq->q)
2144 plug->multiple_queues = true;
2149 * Allow 2x BLK_MAX_REQUEST_COUNT requests on plug queue for multiple
2150 * queues. This is important for md arrays to benefit from merging
2153 static inline unsigned short blk_plug_max_rq_count(struct blk_plug *plug)
2155 if (plug->multiple_queues)
2156 return BLK_MAX_REQUEST_COUNT * 2;
2157 return BLK_MAX_REQUEST_COUNT;
2161 * blk_mq_submit_bio - Create and send a request to block device.
2162 * @bio: Bio pointer.
2164 * Builds up a request structure from @q and @bio and send to the device. The
2165 * request may not be queued directly to hardware if:
2166 * * This request can be merged with another one
2167 * * We want to place request at plug queue for possible future merging
2168 * * There is an IO scheduler active at this queue
2170 * It will not queue the request if there is an error with the bio, or at the
2173 * Returns: Request queue cookie.
2175 blk_qc_t blk_mq_submit_bio(struct bio *bio)
2177 struct request_queue *q = bio->bi_bdev->bd_disk->queue;
2178 const int is_sync = op_is_sync(bio->bi_opf);
2179 const int is_flush_fua = op_is_flush(bio->bi_opf);
2180 struct blk_mq_alloc_data data = {
2184 struct blk_plug *plug;
2185 struct request *same_queue_rq = NULL;
2186 unsigned int nr_segs;
2191 blk_queue_bounce(q, &bio);
2192 __blk_queue_split(&bio, &nr_segs);
2194 if (!bio_integrity_prep(bio))
2197 if (!is_flush_fua && !blk_queue_nomerges(q) &&
2198 blk_attempt_plug_merge(q, bio, nr_segs, &same_queue_rq))
2201 if (blk_mq_sched_bio_merge(q, bio, nr_segs))
2204 rq_qos_throttle(q, bio);
2206 hipri = bio->bi_opf & REQ_HIPRI;
2208 data.cmd_flags = bio->bi_opf;
2209 rq = __blk_mq_alloc_request(&data);
2210 if (unlikely(!rq)) {
2211 rq_qos_cleanup(q, bio);
2212 if (bio->bi_opf & REQ_NOWAIT)
2213 bio_wouldblock_error(bio);
2217 trace_block_getrq(bio);
2219 rq_qos_track(q, rq, bio);
2221 cookie = request_to_qc_t(data.hctx, rq);
2223 blk_mq_bio_to_request(rq, bio, nr_segs);
2225 ret = blk_crypto_init_request(rq);
2226 if (ret != BLK_STS_OK) {
2227 bio->bi_status = ret;
2229 blk_mq_free_request(rq);
2230 return BLK_QC_T_NONE;
2233 plug = blk_mq_plug(q, bio);
2234 if (unlikely(is_flush_fua)) {
2235 /* Bypass scheduler for flush requests */
2236 blk_insert_flush(rq);
2237 blk_mq_run_hw_queue(data.hctx, true);
2238 } else if (plug && (q->nr_hw_queues == 1 ||
2239 blk_mq_is_sbitmap_shared(rq->mq_hctx->flags) ||
2240 q->mq_ops->commit_rqs || !blk_queue_nonrot(q))) {
2242 * Use plugging if we have a ->commit_rqs() hook as well, as
2243 * we know the driver uses bd->last in a smart fashion.
2245 * Use normal plugging if this disk is slow HDD, as sequential
2246 * IO may benefit a lot from plug merging.
2248 unsigned int request_count = plug->rq_count;
2249 struct request *last = NULL;
2252 trace_block_plug(q);
2254 last = list_entry_rq(plug->mq_list.prev);
2256 if (request_count >= blk_plug_max_rq_count(plug) || (last &&
2257 blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
2258 blk_flush_plug_list(plug, false);
2259 trace_block_plug(q);
2262 blk_add_rq_to_plug(plug, rq);
2263 } else if (q->elevator) {
2264 /* Insert the request at the IO scheduler queue */
2265 blk_mq_sched_insert_request(rq, false, true, true);
2266 } else if (plug && !blk_queue_nomerges(q)) {
2268 * We do limited plugging. If the bio can be merged, do that.
2269 * Otherwise the existing request in the plug list will be
2270 * issued. So the plug list will have one request at most
2271 * The plug list might get flushed before this. If that happens,
2272 * the plug list is empty, and same_queue_rq is invalid.
2274 if (list_empty(&plug->mq_list))
2275 same_queue_rq = NULL;
2276 if (same_queue_rq) {
2277 list_del_init(&same_queue_rq->queuelist);
2280 blk_add_rq_to_plug(plug, rq);
2281 trace_block_plug(q);
2283 if (same_queue_rq) {
2284 data.hctx = same_queue_rq->mq_hctx;
2285 trace_block_unplug(q, 1, true);
2286 blk_mq_try_issue_directly(data.hctx, same_queue_rq,
2289 } else if ((q->nr_hw_queues > 1 && is_sync) ||
2290 !data.hctx->dispatch_busy) {
2292 * There is no scheduler and we can try to send directly
2295 blk_mq_try_issue_directly(data.hctx, rq, &cookie);
2298 blk_mq_sched_insert_request(rq, false, true, true);
2302 return BLK_QC_T_NONE;
2306 return BLK_QC_T_NONE;
2309 static size_t order_to_size(unsigned int order)
2311 return (size_t)PAGE_SIZE << order;
2314 /* called before freeing request pool in @tags */
2315 static void blk_mq_clear_rq_mapping(struct blk_mq_tag_set *set,
2316 struct blk_mq_tags *tags, unsigned int hctx_idx)
2318 struct blk_mq_tags *drv_tags = set->tags[hctx_idx];
2320 unsigned long flags;
2322 list_for_each_entry(page, &tags->page_list, lru) {
2323 unsigned long start = (unsigned long)page_address(page);
2324 unsigned long end = start + order_to_size(page->private);
2327 for (i = 0; i < set->queue_depth; i++) {
2328 struct request *rq = drv_tags->rqs[i];
2329 unsigned long rq_addr = (unsigned long)rq;
2331 if (rq_addr >= start && rq_addr < end) {
2332 WARN_ON_ONCE(refcount_read(&rq->ref) != 0);
2333 cmpxchg(&drv_tags->rqs[i], rq, NULL);
2339 * Wait until all pending iteration is done.
2341 * Request reference is cleared and it is guaranteed to be observed
2342 * after the ->lock is released.
2344 spin_lock_irqsave(&drv_tags->lock, flags);
2345 spin_unlock_irqrestore(&drv_tags->lock, flags);
2348 void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
2349 unsigned int hctx_idx)
2353 if (tags->rqs && set->ops->exit_request) {
2356 for (i = 0; i < tags->nr_tags; i++) {
2357 struct request *rq = tags->static_rqs[i];
2361 set->ops->exit_request(set, rq, hctx_idx);
2362 tags->static_rqs[i] = NULL;
2366 blk_mq_clear_rq_mapping(set, tags, hctx_idx);
2368 while (!list_empty(&tags->page_list)) {
2369 page = list_first_entry(&tags->page_list, struct page, lru);
2370 list_del_init(&page->lru);
2372 * Remove kmemleak object previously allocated in
2373 * blk_mq_alloc_rqs().
2375 kmemleak_free(page_address(page));
2376 __free_pages(page, page->private);
2380 void blk_mq_free_rq_map(struct blk_mq_tags *tags, unsigned int flags)
2384 kfree(tags->static_rqs);
2385 tags->static_rqs = NULL;
2387 blk_mq_free_tags(tags, flags);
2390 struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set,
2391 unsigned int hctx_idx,
2392 unsigned int nr_tags,
2393 unsigned int reserved_tags,
2396 struct blk_mq_tags *tags;
2399 node = blk_mq_hw_queue_to_node(&set->map[HCTX_TYPE_DEFAULT], hctx_idx);
2400 if (node == NUMA_NO_NODE)
2401 node = set->numa_node;
2403 tags = blk_mq_init_tags(nr_tags, reserved_tags, node, flags);
2407 tags->rqs = kcalloc_node(nr_tags, sizeof(struct request *),
2408 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
2411 blk_mq_free_tags(tags, flags);
2415 tags->static_rqs = kcalloc_node(nr_tags, sizeof(struct request *),
2416 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
2418 if (!tags->static_rqs) {
2420 blk_mq_free_tags(tags, flags);
2427 static int blk_mq_init_request(struct blk_mq_tag_set *set, struct request *rq,
2428 unsigned int hctx_idx, int node)
2432 if (set->ops->init_request) {
2433 ret = set->ops->init_request(set, rq, hctx_idx, node);
2438 WRITE_ONCE(rq->state, MQ_RQ_IDLE);
2442 int blk_mq_alloc_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
2443 unsigned int hctx_idx, unsigned int depth)
2445 unsigned int i, j, entries_per_page, max_order = 4;
2446 size_t rq_size, left;
2449 node = blk_mq_hw_queue_to_node(&set->map[HCTX_TYPE_DEFAULT], hctx_idx);
2450 if (node == NUMA_NO_NODE)
2451 node = set->numa_node;
2453 INIT_LIST_HEAD(&tags->page_list);
2456 * rq_size is the size of the request plus driver payload, rounded
2457 * to the cacheline size
2459 rq_size = round_up(sizeof(struct request) + set->cmd_size,
2461 left = rq_size * depth;
2463 for (i = 0; i < depth; ) {
2464 int this_order = max_order;
2469 while (this_order && left < order_to_size(this_order - 1))
2473 page = alloc_pages_node(node,
2474 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY | __GFP_ZERO,
2480 if (order_to_size(this_order) < rq_size)
2487 page->private = this_order;
2488 list_add_tail(&page->lru, &tags->page_list);
2490 p = page_address(page);
2492 * Allow kmemleak to scan these pages as they contain pointers
2493 * to additional allocations like via ops->init_request().
2495 kmemleak_alloc(p, order_to_size(this_order), 1, GFP_NOIO);
2496 entries_per_page = order_to_size(this_order) / rq_size;
2497 to_do = min(entries_per_page, depth - i);
2498 left -= to_do * rq_size;
2499 for (j = 0; j < to_do; j++) {
2500 struct request *rq = p;
2502 tags->static_rqs[i] = rq;
2503 if (blk_mq_init_request(set, rq, hctx_idx, node)) {
2504 tags->static_rqs[i] = NULL;
2515 blk_mq_free_rqs(set, tags, hctx_idx);
2519 struct rq_iter_data {
2520 struct blk_mq_hw_ctx *hctx;
2524 static bool blk_mq_has_request(struct request *rq, void *data, bool reserved)
2526 struct rq_iter_data *iter_data = data;
2528 if (rq->mq_hctx != iter_data->hctx)
2530 iter_data->has_rq = true;
2534 static bool blk_mq_hctx_has_requests(struct blk_mq_hw_ctx *hctx)
2536 struct blk_mq_tags *tags = hctx->sched_tags ?
2537 hctx->sched_tags : hctx->tags;
2538 struct rq_iter_data data = {
2542 blk_mq_all_tag_iter(tags, blk_mq_has_request, &data);
2546 static inline bool blk_mq_last_cpu_in_hctx(unsigned int cpu,
2547 struct blk_mq_hw_ctx *hctx)
2549 if (cpumask_next_and(-1, hctx->cpumask, cpu_online_mask) != cpu)
2551 if (cpumask_next_and(cpu, hctx->cpumask, cpu_online_mask) < nr_cpu_ids)
2556 static int blk_mq_hctx_notify_offline(unsigned int cpu, struct hlist_node *node)
2558 struct blk_mq_hw_ctx *hctx = hlist_entry_safe(node,
2559 struct blk_mq_hw_ctx, cpuhp_online);
2561 if (!cpumask_test_cpu(cpu, hctx->cpumask) ||
2562 !blk_mq_last_cpu_in_hctx(cpu, hctx))
2566 * Prevent new request from being allocated on the current hctx.
2568 * The smp_mb__after_atomic() Pairs with the implied barrier in
2569 * test_and_set_bit_lock in sbitmap_get(). Ensures the inactive flag is
2570 * seen once we return from the tag allocator.
2572 set_bit(BLK_MQ_S_INACTIVE, &hctx->state);
2573 smp_mb__after_atomic();
2576 * Try to grab a reference to the queue and wait for any outstanding
2577 * requests. If we could not grab a reference the queue has been
2578 * frozen and there are no requests.
2580 if (percpu_ref_tryget(&hctx->queue->q_usage_counter)) {
2581 while (blk_mq_hctx_has_requests(hctx))
2583 percpu_ref_put(&hctx->queue->q_usage_counter);
2589 static int blk_mq_hctx_notify_online(unsigned int cpu, struct hlist_node *node)
2591 struct blk_mq_hw_ctx *hctx = hlist_entry_safe(node,
2592 struct blk_mq_hw_ctx, cpuhp_online);
2594 if (cpumask_test_cpu(cpu, hctx->cpumask))
2595 clear_bit(BLK_MQ_S_INACTIVE, &hctx->state);
2600 * 'cpu' is going away. splice any existing rq_list entries from this
2601 * software queue to the hw queue dispatch list, and ensure that it
2604 static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node)
2606 struct blk_mq_hw_ctx *hctx;
2607 struct blk_mq_ctx *ctx;
2609 enum hctx_type type;
2611 hctx = hlist_entry_safe(node, struct blk_mq_hw_ctx, cpuhp_dead);
2612 if (!cpumask_test_cpu(cpu, hctx->cpumask))
2615 ctx = __blk_mq_get_ctx(hctx->queue, cpu);
2618 spin_lock(&ctx->lock);
2619 if (!list_empty(&ctx->rq_lists[type])) {
2620 list_splice_init(&ctx->rq_lists[type], &tmp);
2621 blk_mq_hctx_clear_pending(hctx, ctx);
2623 spin_unlock(&ctx->lock);
2625 if (list_empty(&tmp))
2628 spin_lock(&hctx->lock);
2629 list_splice_tail_init(&tmp, &hctx->dispatch);
2630 spin_unlock(&hctx->lock);
2632 blk_mq_run_hw_queue(hctx, true);
2636 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx *hctx)
2638 if (!(hctx->flags & BLK_MQ_F_STACKING))
2639 cpuhp_state_remove_instance_nocalls(CPUHP_AP_BLK_MQ_ONLINE,
2640 &hctx->cpuhp_online);
2641 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD,
2646 * Before freeing hw queue, clearing the flush request reference in
2647 * tags->rqs[] for avoiding potential UAF.
2649 static void blk_mq_clear_flush_rq_mapping(struct blk_mq_tags *tags,
2650 unsigned int queue_depth, struct request *flush_rq)
2653 unsigned long flags;
2655 /* The hw queue may not be mapped yet */
2659 WARN_ON_ONCE(refcount_read(&flush_rq->ref) != 0);
2661 for (i = 0; i < queue_depth; i++)
2662 cmpxchg(&tags->rqs[i], flush_rq, NULL);
2665 * Wait until all pending iteration is done.
2667 * Request reference is cleared and it is guaranteed to be observed
2668 * after the ->lock is released.
2670 spin_lock_irqsave(&tags->lock, flags);
2671 spin_unlock_irqrestore(&tags->lock, flags);
2674 /* hctx->ctxs will be freed in queue's release handler */
2675 static void blk_mq_exit_hctx(struct request_queue *q,
2676 struct blk_mq_tag_set *set,
2677 struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
2679 struct request *flush_rq = hctx->fq->flush_rq;
2681 if (blk_mq_hw_queue_mapped(hctx))
2682 blk_mq_tag_idle(hctx);
2684 blk_mq_clear_flush_rq_mapping(set->tags[hctx_idx],
2685 set->queue_depth, flush_rq);
2686 if (set->ops->exit_request)
2687 set->ops->exit_request(set, flush_rq, hctx_idx);
2689 if (set->ops->exit_hctx)
2690 set->ops->exit_hctx(hctx, hctx_idx);
2692 blk_mq_remove_cpuhp(hctx);
2694 spin_lock(&q->unused_hctx_lock);
2695 list_add(&hctx->hctx_list, &q->unused_hctx_list);
2696 spin_unlock(&q->unused_hctx_lock);
2699 static void blk_mq_exit_hw_queues(struct request_queue *q,
2700 struct blk_mq_tag_set *set, int nr_queue)
2702 struct blk_mq_hw_ctx *hctx;
2705 queue_for_each_hw_ctx(q, hctx, i) {
2708 blk_mq_debugfs_unregister_hctx(hctx);
2709 blk_mq_exit_hctx(q, set, hctx, i);
2713 static int blk_mq_hw_ctx_size(struct blk_mq_tag_set *tag_set)
2715 int hw_ctx_size = sizeof(struct blk_mq_hw_ctx);
2717 BUILD_BUG_ON(ALIGN(offsetof(struct blk_mq_hw_ctx, srcu),
2718 __alignof__(struct blk_mq_hw_ctx)) !=
2719 sizeof(struct blk_mq_hw_ctx));
2721 if (tag_set->flags & BLK_MQ_F_BLOCKING)
2722 hw_ctx_size += sizeof(struct srcu_struct);
2727 static int blk_mq_init_hctx(struct request_queue *q,
2728 struct blk_mq_tag_set *set,
2729 struct blk_mq_hw_ctx *hctx, unsigned hctx_idx)
2731 hctx->queue_num = hctx_idx;
2733 if (!(hctx->flags & BLK_MQ_F_STACKING))
2734 cpuhp_state_add_instance_nocalls(CPUHP_AP_BLK_MQ_ONLINE,
2735 &hctx->cpuhp_online);
2736 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD, &hctx->cpuhp_dead);
2738 hctx->tags = set->tags[hctx_idx];
2740 if (set->ops->init_hctx &&
2741 set->ops->init_hctx(hctx, set->driver_data, hctx_idx))
2742 goto unregister_cpu_notifier;
2744 if (blk_mq_init_request(set, hctx->fq->flush_rq, hctx_idx,
2750 if (set->ops->exit_hctx)
2751 set->ops->exit_hctx(hctx, hctx_idx);
2752 unregister_cpu_notifier:
2753 blk_mq_remove_cpuhp(hctx);
2757 static struct blk_mq_hw_ctx *
2758 blk_mq_alloc_hctx(struct request_queue *q, struct blk_mq_tag_set *set,
2761 struct blk_mq_hw_ctx *hctx;
2762 gfp_t gfp = GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY;
2764 hctx = kzalloc_node(blk_mq_hw_ctx_size(set), gfp, node);
2766 goto fail_alloc_hctx;
2768 if (!zalloc_cpumask_var_node(&hctx->cpumask, gfp, node))
2771 atomic_set(&hctx->nr_active, 0);
2772 if (node == NUMA_NO_NODE)
2773 node = set->numa_node;
2774 hctx->numa_node = node;
2776 INIT_DELAYED_WORK(&hctx->run_work, blk_mq_run_work_fn);
2777 spin_lock_init(&hctx->lock);
2778 INIT_LIST_HEAD(&hctx->dispatch);
2780 hctx->flags = set->flags & ~BLK_MQ_F_TAG_QUEUE_SHARED;
2782 INIT_LIST_HEAD(&hctx->hctx_list);
2785 * Allocate space for all possible cpus to avoid allocation at
2788 hctx->ctxs = kmalloc_array_node(nr_cpu_ids, sizeof(void *),
2793 if (sbitmap_init_node(&hctx->ctx_map, nr_cpu_ids, ilog2(8),
2794 gfp, node, false, false))
2798 spin_lock_init(&hctx->dispatch_wait_lock);
2799 init_waitqueue_func_entry(&hctx->dispatch_wait, blk_mq_dispatch_wake);
2800 INIT_LIST_HEAD(&hctx->dispatch_wait.entry);
2802 hctx->fq = blk_alloc_flush_queue(hctx->numa_node, set->cmd_size, gfp);
2806 if (hctx->flags & BLK_MQ_F_BLOCKING)
2807 init_srcu_struct(hctx->srcu);
2808 blk_mq_hctx_kobj_init(hctx);
2813 sbitmap_free(&hctx->ctx_map);
2817 free_cpumask_var(hctx->cpumask);
2824 static void blk_mq_init_cpu_queues(struct request_queue *q,
2825 unsigned int nr_hw_queues)
2827 struct blk_mq_tag_set *set = q->tag_set;
2830 for_each_possible_cpu(i) {
2831 struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
2832 struct blk_mq_hw_ctx *hctx;
2836 spin_lock_init(&__ctx->lock);
2837 for (k = HCTX_TYPE_DEFAULT; k < HCTX_MAX_TYPES; k++)
2838 INIT_LIST_HEAD(&__ctx->rq_lists[k]);
2843 * Set local node, IFF we have more than one hw queue. If
2844 * not, we remain on the home node of the device
2846 for (j = 0; j < set->nr_maps; j++) {
2847 hctx = blk_mq_map_queue_type(q, j, i);
2848 if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE)
2849 hctx->numa_node = cpu_to_node(i);
2854 static bool __blk_mq_alloc_map_and_request(struct blk_mq_tag_set *set,
2857 unsigned int flags = set->flags;
2860 set->tags[hctx_idx] = blk_mq_alloc_rq_map(set, hctx_idx,
2861 set->queue_depth, set->reserved_tags, flags);
2862 if (!set->tags[hctx_idx])
2865 ret = blk_mq_alloc_rqs(set, set->tags[hctx_idx], hctx_idx,
2870 blk_mq_free_rq_map(set->tags[hctx_idx], flags);
2871 set->tags[hctx_idx] = NULL;
2875 static void blk_mq_free_map_and_requests(struct blk_mq_tag_set *set,
2876 unsigned int hctx_idx)
2878 unsigned int flags = set->flags;
2880 if (set->tags && set->tags[hctx_idx]) {
2881 blk_mq_free_rqs(set, set->tags[hctx_idx], hctx_idx);
2882 blk_mq_free_rq_map(set->tags[hctx_idx], flags);
2883 set->tags[hctx_idx] = NULL;
2887 static void blk_mq_map_swqueue(struct request_queue *q)
2889 unsigned int i, j, hctx_idx;
2890 struct blk_mq_hw_ctx *hctx;
2891 struct blk_mq_ctx *ctx;
2892 struct blk_mq_tag_set *set = q->tag_set;
2894 queue_for_each_hw_ctx(q, hctx, i) {
2895 cpumask_clear(hctx->cpumask);
2897 hctx->dispatch_from = NULL;
2901 * Map software to hardware queues.
2903 * If the cpu isn't present, the cpu is mapped to first hctx.
2905 for_each_possible_cpu(i) {
2907 ctx = per_cpu_ptr(q->queue_ctx, i);
2908 for (j = 0; j < set->nr_maps; j++) {
2909 if (!set->map[j].nr_queues) {
2910 ctx->hctxs[j] = blk_mq_map_queue_type(q,
2911 HCTX_TYPE_DEFAULT, i);
2914 hctx_idx = set->map[j].mq_map[i];
2915 /* unmapped hw queue can be remapped after CPU topo changed */
2916 if (!set->tags[hctx_idx] &&
2917 !__blk_mq_alloc_map_and_request(set, hctx_idx)) {
2919 * If tags initialization fail for some hctx,
2920 * that hctx won't be brought online. In this
2921 * case, remap the current ctx to hctx[0] which
2922 * is guaranteed to always have tags allocated
2924 set->map[j].mq_map[i] = 0;
2927 hctx = blk_mq_map_queue_type(q, j, i);
2928 ctx->hctxs[j] = hctx;
2930 * If the CPU is already set in the mask, then we've
2931 * mapped this one already. This can happen if
2932 * devices share queues across queue maps.
2934 if (cpumask_test_cpu(i, hctx->cpumask))
2937 cpumask_set_cpu(i, hctx->cpumask);
2939 ctx->index_hw[hctx->type] = hctx->nr_ctx;
2940 hctx->ctxs[hctx->nr_ctx++] = ctx;
2943 * If the nr_ctx type overflows, we have exceeded the
2944 * amount of sw queues we can support.
2946 BUG_ON(!hctx->nr_ctx);
2949 for (; j < HCTX_MAX_TYPES; j++)
2950 ctx->hctxs[j] = blk_mq_map_queue_type(q,
2951 HCTX_TYPE_DEFAULT, i);
2954 queue_for_each_hw_ctx(q, hctx, i) {
2956 * If no software queues are mapped to this hardware queue,
2957 * disable it and free the request entries.
2959 if (!hctx->nr_ctx) {
2960 /* Never unmap queue 0. We need it as a
2961 * fallback in case of a new remap fails
2964 if (i && set->tags[i])
2965 blk_mq_free_map_and_requests(set, i);
2971 hctx->tags = set->tags[i];
2972 WARN_ON(!hctx->tags);
2975 * Set the map size to the number of mapped software queues.
2976 * This is more accurate and more efficient than looping
2977 * over all possibly mapped software queues.
2979 sbitmap_resize(&hctx->ctx_map, hctx->nr_ctx);
2982 * Initialize batch roundrobin counts
2984 hctx->next_cpu = blk_mq_first_mapped_cpu(hctx);
2985 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
2990 * Caller needs to ensure that we're either frozen/quiesced, or that
2991 * the queue isn't live yet.
2993 static void queue_set_hctx_shared(struct request_queue *q, bool shared)
2995 struct blk_mq_hw_ctx *hctx;
2998 queue_for_each_hw_ctx(q, hctx, i) {
3000 hctx->flags |= BLK_MQ_F_TAG_QUEUE_SHARED;
3002 blk_mq_tag_idle(hctx);
3003 hctx->flags &= ~BLK_MQ_F_TAG_QUEUE_SHARED;
3008 static void blk_mq_update_tag_set_shared(struct blk_mq_tag_set *set,
3011 struct request_queue *q;
3013 lockdep_assert_held(&set->tag_list_lock);
3015 list_for_each_entry(q, &set->tag_list, tag_set_list) {
3016 blk_mq_freeze_queue(q);
3017 queue_set_hctx_shared(q, shared);
3018 blk_mq_unfreeze_queue(q);
3022 static void blk_mq_del_queue_tag_set(struct request_queue *q)
3024 struct blk_mq_tag_set *set = q->tag_set;
3026 mutex_lock(&set->tag_list_lock);
3027 list_del(&q->tag_set_list);
3028 if (list_is_singular(&set->tag_list)) {
3029 /* just transitioned to unshared */
3030 set->flags &= ~BLK_MQ_F_TAG_QUEUE_SHARED;
3031 /* update existing queue */
3032 blk_mq_update_tag_set_shared(set, false);
3034 mutex_unlock(&set->tag_list_lock);
3035 INIT_LIST_HEAD(&q->tag_set_list);
3038 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
3039 struct request_queue *q)
3041 mutex_lock(&set->tag_list_lock);
3044 * Check to see if we're transitioning to shared (from 1 to 2 queues).
3046 if (!list_empty(&set->tag_list) &&
3047 !(set->flags & BLK_MQ_F_TAG_QUEUE_SHARED)) {
3048 set->flags |= BLK_MQ_F_TAG_QUEUE_SHARED;
3049 /* update existing queue */
3050 blk_mq_update_tag_set_shared(set, true);
3052 if (set->flags & BLK_MQ_F_TAG_QUEUE_SHARED)
3053 queue_set_hctx_shared(q, true);
3054 list_add_tail(&q->tag_set_list, &set->tag_list);
3056 mutex_unlock(&set->tag_list_lock);
3059 /* All allocations will be freed in release handler of q->mq_kobj */
3060 static int blk_mq_alloc_ctxs(struct request_queue *q)
3062 struct blk_mq_ctxs *ctxs;
3065 ctxs = kzalloc(sizeof(*ctxs), GFP_KERNEL);
3069 ctxs->queue_ctx = alloc_percpu(struct blk_mq_ctx);
3070 if (!ctxs->queue_ctx)
3073 for_each_possible_cpu(cpu) {
3074 struct blk_mq_ctx *ctx = per_cpu_ptr(ctxs->queue_ctx, cpu);
3078 q->mq_kobj = &ctxs->kobj;
3079 q->queue_ctx = ctxs->queue_ctx;
3088 * It is the actual release handler for mq, but we do it from
3089 * request queue's release handler for avoiding use-after-free
3090 * and headache because q->mq_kobj shouldn't have been introduced,
3091 * but we can't group ctx/kctx kobj without it.
3093 void blk_mq_release(struct request_queue *q)
3095 struct blk_mq_hw_ctx *hctx, *next;
3098 queue_for_each_hw_ctx(q, hctx, i)
3099 WARN_ON_ONCE(hctx && list_empty(&hctx->hctx_list));
3101 /* all hctx are in .unused_hctx_list now */
3102 list_for_each_entry_safe(hctx, next, &q->unused_hctx_list, hctx_list) {
3103 list_del_init(&hctx->hctx_list);
3104 kobject_put(&hctx->kobj);
3107 kfree(q->queue_hw_ctx);
3110 * release .mq_kobj and sw queue's kobject now because
3111 * both share lifetime with request queue.
3113 blk_mq_sysfs_deinit(q);
3116 static struct request_queue *blk_mq_init_queue_data(struct blk_mq_tag_set *set,
3119 struct request_queue *q;
3122 q = blk_alloc_queue(set->numa_node);
3124 return ERR_PTR(-ENOMEM);
3125 q->queuedata = queuedata;
3126 ret = blk_mq_init_allocated_queue(set, q);
3128 blk_cleanup_queue(q);
3129 return ERR_PTR(ret);
3134 struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
3136 return blk_mq_init_queue_data(set, NULL);
3138 EXPORT_SYMBOL(blk_mq_init_queue);
3140 struct gendisk *__blk_mq_alloc_disk(struct blk_mq_tag_set *set, void *queuedata,
3141 struct lock_class_key *lkclass)
3143 struct request_queue *q;
3144 struct gendisk *disk;
3146 q = blk_mq_init_queue_data(set, queuedata);
3150 disk = __alloc_disk_node(q, set->numa_node, lkclass);
3152 blk_cleanup_queue(q);
3153 return ERR_PTR(-ENOMEM);
3157 EXPORT_SYMBOL(__blk_mq_alloc_disk);
3159 static struct blk_mq_hw_ctx *blk_mq_alloc_and_init_hctx(
3160 struct blk_mq_tag_set *set, struct request_queue *q,
3161 int hctx_idx, int node)
3163 struct blk_mq_hw_ctx *hctx = NULL, *tmp;
3165 /* reuse dead hctx first */
3166 spin_lock(&q->unused_hctx_lock);
3167 list_for_each_entry(tmp, &q->unused_hctx_list, hctx_list) {
3168 if (tmp->numa_node == node) {
3174 list_del_init(&hctx->hctx_list);
3175 spin_unlock(&q->unused_hctx_lock);
3178 hctx = blk_mq_alloc_hctx(q, set, node);
3182 if (blk_mq_init_hctx(q, set, hctx, hctx_idx))
3188 kobject_put(&hctx->kobj);
3193 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
3194 struct request_queue *q)
3197 struct blk_mq_hw_ctx **hctxs = q->queue_hw_ctx;
3199 if (q->nr_hw_queues < set->nr_hw_queues) {
3200 struct blk_mq_hw_ctx **new_hctxs;
3202 new_hctxs = kcalloc_node(set->nr_hw_queues,
3203 sizeof(*new_hctxs), GFP_KERNEL,
3208 memcpy(new_hctxs, hctxs, q->nr_hw_queues *
3210 q->queue_hw_ctx = new_hctxs;
3215 /* protect against switching io scheduler */
3216 mutex_lock(&q->sysfs_lock);
3217 for (i = 0; i < set->nr_hw_queues; i++) {
3219 struct blk_mq_hw_ctx *hctx;
3221 node = blk_mq_hw_queue_to_node(&set->map[HCTX_TYPE_DEFAULT], i);
3223 * If the hw queue has been mapped to another numa node,
3224 * we need to realloc the hctx. If allocation fails, fallback
3225 * to use the previous one.
3227 if (hctxs[i] && (hctxs[i]->numa_node == node))
3230 hctx = blk_mq_alloc_and_init_hctx(set, q, i, node);
3233 blk_mq_exit_hctx(q, set, hctxs[i], i);
3237 pr_warn("Allocate new hctx on node %d fails,\
3238 fallback to previous one on node %d\n",
3239 node, hctxs[i]->numa_node);
3245 * Increasing nr_hw_queues fails. Free the newly allocated
3246 * hctxs and keep the previous q->nr_hw_queues.
3248 if (i != set->nr_hw_queues) {
3249 j = q->nr_hw_queues;
3253 end = q->nr_hw_queues;
3254 q->nr_hw_queues = set->nr_hw_queues;
3257 for (; j < end; j++) {
3258 struct blk_mq_hw_ctx *hctx = hctxs[j];
3262 blk_mq_free_map_and_requests(set, j);
3263 blk_mq_exit_hctx(q, set, hctx, j);
3267 mutex_unlock(&q->sysfs_lock);
3270 int blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
3271 struct request_queue *q)
3273 /* mark the queue as mq asap */
3274 q->mq_ops = set->ops;
3276 q->poll_cb = blk_stat_alloc_callback(blk_mq_poll_stats_fn,
3277 blk_mq_poll_stats_bkt,
3278 BLK_MQ_POLL_STATS_BKTS, q);
3282 if (blk_mq_alloc_ctxs(q))
3285 /* init q->mq_kobj and sw queues' kobjects */
3286 blk_mq_sysfs_init(q);
3288 INIT_LIST_HEAD(&q->unused_hctx_list);
3289 spin_lock_init(&q->unused_hctx_lock);
3291 blk_mq_realloc_hw_ctxs(set, q);
3292 if (!q->nr_hw_queues)
3295 INIT_WORK(&q->timeout_work, blk_mq_timeout_work);
3296 blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);
3300 q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
3301 if (set->nr_maps > HCTX_TYPE_POLL &&
3302 set->map[HCTX_TYPE_POLL].nr_queues)
3303 blk_queue_flag_set(QUEUE_FLAG_POLL, q);
3305 INIT_DELAYED_WORK(&q->requeue_work, blk_mq_requeue_work);
3306 INIT_LIST_HEAD(&q->requeue_list);
3307 spin_lock_init(&q->requeue_lock);
3309 q->nr_requests = set->queue_depth;
3312 * Default to classic polling
3314 q->poll_nsec = BLK_MQ_POLL_CLASSIC;
3316 blk_mq_init_cpu_queues(q, set->nr_hw_queues);
3317 blk_mq_add_queue_tag_set(set, q);
3318 blk_mq_map_swqueue(q);
3322 kfree(q->queue_hw_ctx);
3323 q->nr_hw_queues = 0;
3324 blk_mq_sysfs_deinit(q);
3326 blk_stat_free_callback(q->poll_cb);
3332 EXPORT_SYMBOL(blk_mq_init_allocated_queue);
3334 /* tags can _not_ be used after returning from blk_mq_exit_queue */
3335 void blk_mq_exit_queue(struct request_queue *q)
3337 struct blk_mq_tag_set *set = q->tag_set;
3339 /* Checks hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED. */
3340 blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
3341 /* May clear BLK_MQ_F_TAG_QUEUE_SHARED in hctx->flags. */
3342 blk_mq_del_queue_tag_set(q);
3345 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
3349 for (i = 0; i < set->nr_hw_queues; i++) {
3350 if (!__blk_mq_alloc_map_and_request(set, i))
3359 blk_mq_free_map_and_requests(set, i);
3365 * Allocate the request maps associated with this tag_set. Note that this
3366 * may reduce the depth asked for, if memory is tight. set->queue_depth
3367 * will be updated to reflect the allocated depth.
3369 static int blk_mq_alloc_map_and_requests(struct blk_mq_tag_set *set)
3374 depth = set->queue_depth;
3376 err = __blk_mq_alloc_rq_maps(set);
3380 set->queue_depth >>= 1;
3381 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN) {
3385 } while (set->queue_depth);
3387 if (!set->queue_depth || err) {
3388 pr_err("blk-mq: failed to allocate request map\n");
3392 if (depth != set->queue_depth)
3393 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
3394 depth, set->queue_depth);
3399 static int blk_mq_update_queue_map(struct blk_mq_tag_set *set)
3402 * blk_mq_map_queues() and multiple .map_queues() implementations
3403 * expect that set->map[HCTX_TYPE_DEFAULT].nr_queues is set to the
3404 * number of hardware queues.
3406 if (set->nr_maps == 1)
3407 set->map[HCTX_TYPE_DEFAULT].nr_queues = set->nr_hw_queues;
3409 if (set->ops->map_queues && !is_kdump_kernel()) {
3413 * transport .map_queues is usually done in the following
3416 * for (queue = 0; queue < set->nr_hw_queues; queue++) {
3417 * mask = get_cpu_mask(queue)
3418 * for_each_cpu(cpu, mask)
3419 * set->map[x].mq_map[cpu] = queue;
3422 * When we need to remap, the table has to be cleared for
3423 * killing stale mapping since one CPU may not be mapped
3426 for (i = 0; i < set->nr_maps; i++)
3427 blk_mq_clear_mq_map(&set->map[i]);
3429 return set->ops->map_queues(set);
3431 BUG_ON(set->nr_maps > 1);
3432 return blk_mq_map_queues(&set->map[HCTX_TYPE_DEFAULT]);
3436 static int blk_mq_realloc_tag_set_tags(struct blk_mq_tag_set *set,
3437 int cur_nr_hw_queues, int new_nr_hw_queues)
3439 struct blk_mq_tags **new_tags;
3441 if (cur_nr_hw_queues >= new_nr_hw_queues)
3444 new_tags = kcalloc_node(new_nr_hw_queues, sizeof(struct blk_mq_tags *),
3445 GFP_KERNEL, set->numa_node);
3450 memcpy(new_tags, set->tags, cur_nr_hw_queues *
3451 sizeof(*set->tags));
3453 set->tags = new_tags;
3454 set->nr_hw_queues = new_nr_hw_queues;
3459 static int blk_mq_alloc_tag_set_tags(struct blk_mq_tag_set *set,
3460 int new_nr_hw_queues)
3462 return blk_mq_realloc_tag_set_tags(set, 0, new_nr_hw_queues);
3466 * Alloc a tag set to be associated with one or more request queues.
3467 * May fail with EINVAL for various error conditions. May adjust the
3468 * requested depth down, if it's too large. In that case, the set
3469 * value will be stored in set->queue_depth.
3471 int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
3475 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH > 1 << BLK_MQ_UNIQUE_TAG_BITS);
3477 if (!set->nr_hw_queues)
3479 if (!set->queue_depth)
3481 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN)
3484 if (!set->ops->queue_rq)
3487 if (!set->ops->get_budget ^ !set->ops->put_budget)
3490 if (set->queue_depth > BLK_MQ_MAX_DEPTH) {
3491 pr_info("blk-mq: reduced tag depth to %u\n",
3493 set->queue_depth = BLK_MQ_MAX_DEPTH;
3498 else if (set->nr_maps > HCTX_MAX_TYPES)
3502 * If a crashdump is active, then we are potentially in a very
3503 * memory constrained environment. Limit us to 1 queue and
3504 * 64 tags to prevent using too much memory.
3506 if (is_kdump_kernel()) {
3507 set->nr_hw_queues = 1;
3509 set->queue_depth = min(64U, set->queue_depth);
3512 * There is no use for more h/w queues than cpus if we just have
3515 if (set->nr_maps == 1 && set->nr_hw_queues > nr_cpu_ids)
3516 set->nr_hw_queues = nr_cpu_ids;
3518 if (blk_mq_alloc_tag_set_tags(set, set->nr_hw_queues) < 0)
3522 for (i = 0; i < set->nr_maps; i++) {
3523 set->map[i].mq_map = kcalloc_node(nr_cpu_ids,
3524 sizeof(set->map[i].mq_map[0]),
3525 GFP_KERNEL, set->numa_node);
3526 if (!set->map[i].mq_map)
3527 goto out_free_mq_map;
3528 set->map[i].nr_queues = is_kdump_kernel() ? 1 : set->nr_hw_queues;
3531 ret = blk_mq_update_queue_map(set);
3533 goto out_free_mq_map;
3535 ret = blk_mq_alloc_map_and_requests(set);
3537 goto out_free_mq_map;
3539 if (blk_mq_is_sbitmap_shared(set->flags)) {
3540 atomic_set(&set->active_queues_shared_sbitmap, 0);
3542 if (blk_mq_init_shared_sbitmap(set)) {
3544 goto out_free_mq_rq_maps;
3548 mutex_init(&set->tag_list_lock);
3549 INIT_LIST_HEAD(&set->tag_list);
3553 out_free_mq_rq_maps:
3554 for (i = 0; i < set->nr_hw_queues; i++)
3555 blk_mq_free_map_and_requests(set, i);
3557 for (i = 0; i < set->nr_maps; i++) {
3558 kfree(set->map[i].mq_map);
3559 set->map[i].mq_map = NULL;
3565 EXPORT_SYMBOL(blk_mq_alloc_tag_set);
3567 /* allocate and initialize a tagset for a simple single-queue device */
3568 int blk_mq_alloc_sq_tag_set(struct blk_mq_tag_set *set,
3569 const struct blk_mq_ops *ops, unsigned int queue_depth,
3570 unsigned int set_flags)
3572 memset(set, 0, sizeof(*set));
3574 set->nr_hw_queues = 1;
3576 set->queue_depth = queue_depth;
3577 set->numa_node = NUMA_NO_NODE;
3578 set->flags = set_flags;
3579 return blk_mq_alloc_tag_set(set);
3581 EXPORT_SYMBOL_GPL(blk_mq_alloc_sq_tag_set);
3583 void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
3587 for (i = 0; i < set->nr_hw_queues; i++)
3588 blk_mq_free_map_and_requests(set, i);
3590 if (blk_mq_is_sbitmap_shared(set->flags))
3591 blk_mq_exit_shared_sbitmap(set);
3593 for (j = 0; j < set->nr_maps; j++) {
3594 kfree(set->map[j].mq_map);
3595 set->map[j].mq_map = NULL;
3601 EXPORT_SYMBOL(blk_mq_free_tag_set);
3603 int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
3605 struct blk_mq_tag_set *set = q->tag_set;
3606 struct blk_mq_hw_ctx *hctx;
3612 if (q->nr_requests == nr)
3615 blk_mq_freeze_queue(q);
3616 blk_mq_quiesce_queue(q);
3619 queue_for_each_hw_ctx(q, hctx, i) {
3623 * If we're using an MQ scheduler, just update the scheduler
3624 * queue depth. This is similar to what the old code would do.
3626 if (!hctx->sched_tags) {
3627 ret = blk_mq_tag_update_depth(hctx, &hctx->tags, nr,
3629 if (!ret && blk_mq_is_sbitmap_shared(set->flags))
3630 blk_mq_tag_resize_shared_sbitmap(set, nr);
3632 ret = blk_mq_tag_update_depth(hctx, &hctx->sched_tags,
3634 if (blk_mq_is_sbitmap_shared(set->flags)) {
3635 hctx->sched_tags->bitmap_tags =
3636 &q->sched_bitmap_tags;
3637 hctx->sched_tags->breserved_tags =
3638 &q->sched_breserved_tags;
3643 if (q->elevator && q->elevator->type->ops.depth_updated)
3644 q->elevator->type->ops.depth_updated(hctx);
3647 q->nr_requests = nr;
3648 if (q->elevator && blk_mq_is_sbitmap_shared(set->flags))
3649 sbitmap_queue_resize(&q->sched_bitmap_tags,
3650 nr - set->reserved_tags);
3653 blk_mq_unquiesce_queue(q);
3654 blk_mq_unfreeze_queue(q);
3660 * request_queue and elevator_type pair.
3661 * It is just used by __blk_mq_update_nr_hw_queues to cache
3662 * the elevator_type associated with a request_queue.
3664 struct blk_mq_qe_pair {
3665 struct list_head node;
3666 struct request_queue *q;
3667 struct elevator_type *type;
3671 * Cache the elevator_type in qe pair list and switch the
3672 * io scheduler to 'none'
3674 static bool blk_mq_elv_switch_none(struct list_head *head,
3675 struct request_queue *q)
3677 struct blk_mq_qe_pair *qe;
3682 qe = kmalloc(sizeof(*qe), GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY);
3686 INIT_LIST_HEAD(&qe->node);
3688 qe->type = q->elevator->type;
3689 list_add(&qe->node, head);
3691 mutex_lock(&q->sysfs_lock);
3693 * After elevator_switch_mq, the previous elevator_queue will be
3694 * released by elevator_release. The reference of the io scheduler
3695 * module get by elevator_get will also be put. So we need to get
3696 * a reference of the io scheduler module here to prevent it to be
3699 __module_get(qe->type->elevator_owner);
3700 elevator_switch_mq(q, NULL);
3701 mutex_unlock(&q->sysfs_lock);
3706 static void blk_mq_elv_switch_back(struct list_head *head,
3707 struct request_queue *q)
3709 struct blk_mq_qe_pair *qe;
3710 struct elevator_type *t = NULL;
3712 list_for_each_entry(qe, head, node)
3721 list_del(&qe->node);
3724 mutex_lock(&q->sysfs_lock);
3725 elevator_switch_mq(q, t);
3726 mutex_unlock(&q->sysfs_lock);
3729 static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set,
3732 struct request_queue *q;
3734 int prev_nr_hw_queues;
3736 lockdep_assert_held(&set->tag_list_lock);
3738 if (set->nr_maps == 1 && nr_hw_queues > nr_cpu_ids)
3739 nr_hw_queues = nr_cpu_ids;
3740 if (nr_hw_queues < 1)
3742 if (set->nr_maps == 1 && nr_hw_queues == set->nr_hw_queues)
3745 list_for_each_entry(q, &set->tag_list, tag_set_list)
3746 blk_mq_freeze_queue(q);
3748 * Switch IO scheduler to 'none', cleaning up the data associated
3749 * with the previous scheduler. We will switch back once we are done
3750 * updating the new sw to hw queue mappings.
3752 list_for_each_entry(q, &set->tag_list, tag_set_list)
3753 if (!blk_mq_elv_switch_none(&head, q))
3756 list_for_each_entry(q, &set->tag_list, tag_set_list) {
3757 blk_mq_debugfs_unregister_hctxs(q);
3758 blk_mq_sysfs_unregister(q);
3761 prev_nr_hw_queues = set->nr_hw_queues;
3762 if (blk_mq_realloc_tag_set_tags(set, set->nr_hw_queues, nr_hw_queues) <
3766 set->nr_hw_queues = nr_hw_queues;
3768 blk_mq_update_queue_map(set);
3769 list_for_each_entry(q, &set->tag_list, tag_set_list) {
3770 blk_mq_realloc_hw_ctxs(set, q);
3771 if (q->nr_hw_queues != set->nr_hw_queues) {
3772 pr_warn("Increasing nr_hw_queues to %d fails, fallback to %d\n",
3773 nr_hw_queues, prev_nr_hw_queues);
3774 set->nr_hw_queues = prev_nr_hw_queues;
3775 blk_mq_map_queues(&set->map[HCTX_TYPE_DEFAULT]);
3778 blk_mq_map_swqueue(q);
3782 list_for_each_entry(q, &set->tag_list, tag_set_list) {
3783 blk_mq_sysfs_register(q);
3784 blk_mq_debugfs_register_hctxs(q);
3788 list_for_each_entry(q, &set->tag_list, tag_set_list)
3789 blk_mq_elv_switch_back(&head, q);
3791 list_for_each_entry(q, &set->tag_list, tag_set_list)
3792 blk_mq_unfreeze_queue(q);
3795 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
3797 mutex_lock(&set->tag_list_lock);
3798 __blk_mq_update_nr_hw_queues(set, nr_hw_queues);
3799 mutex_unlock(&set->tag_list_lock);
3801 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues);
3803 /* Enable polling stats and return whether they were already enabled. */
3804 static bool blk_poll_stats_enable(struct request_queue *q)
3806 if (test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
3807 blk_queue_flag_test_and_set(QUEUE_FLAG_POLL_STATS, q))
3809 blk_stat_add_callback(q, q->poll_cb);
3813 static void blk_mq_poll_stats_start(struct request_queue *q)
3816 * We don't arm the callback if polling stats are not enabled or the
3817 * callback is already active.
3819 if (!test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
3820 blk_stat_is_active(q->poll_cb))
3823 blk_stat_activate_msecs(q->poll_cb, 100);
3826 static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb)
3828 struct request_queue *q = cb->data;
3831 for (bucket = 0; bucket < BLK_MQ_POLL_STATS_BKTS; bucket++) {
3832 if (cb->stat[bucket].nr_samples)
3833 q->poll_stat[bucket] = cb->stat[bucket];
3837 static unsigned long blk_mq_poll_nsecs(struct request_queue *q,
3840 unsigned long ret = 0;
3844 * If stats collection isn't on, don't sleep but turn it on for
3847 if (!blk_poll_stats_enable(q))
3851 * As an optimistic guess, use half of the mean service time
3852 * for this type of request. We can (and should) make this smarter.
3853 * For instance, if the completion latencies are tight, we can
3854 * get closer than just half the mean. This is especially
3855 * important on devices where the completion latencies are longer
3856 * than ~10 usec. We do use the stats for the relevant IO size
3857 * if available which does lead to better estimates.
3859 bucket = blk_mq_poll_stats_bkt(rq);
3863 if (q->poll_stat[bucket].nr_samples)
3864 ret = (q->poll_stat[bucket].mean + 1) / 2;
3869 static bool blk_mq_poll_hybrid_sleep(struct request_queue *q,
3872 struct hrtimer_sleeper hs;
3873 enum hrtimer_mode mode;
3877 if (rq->rq_flags & RQF_MQ_POLL_SLEPT)
3881 * If we get here, hybrid polling is enabled. Hence poll_nsec can be:
3883 * 0: use half of prev avg
3884 * >0: use this specific value
3886 if (q->poll_nsec > 0)
3887 nsecs = q->poll_nsec;
3889 nsecs = blk_mq_poll_nsecs(q, rq);
3894 rq->rq_flags |= RQF_MQ_POLL_SLEPT;
3897 * This will be replaced with the stats tracking code, using
3898 * 'avg_completion_time / 2' as the pre-sleep target.
3902 mode = HRTIMER_MODE_REL;
3903 hrtimer_init_sleeper_on_stack(&hs, CLOCK_MONOTONIC, mode);
3904 hrtimer_set_expires(&hs.timer, kt);
3907 if (blk_mq_rq_state(rq) == MQ_RQ_COMPLETE)
3909 set_current_state(TASK_UNINTERRUPTIBLE);
3910 hrtimer_sleeper_start_expires(&hs, mode);
3913 hrtimer_cancel(&hs.timer);
3914 mode = HRTIMER_MODE_ABS;
3915 } while (hs.task && !signal_pending(current));
3917 __set_current_state(TASK_RUNNING);
3918 destroy_hrtimer_on_stack(&hs.timer);
3922 static bool blk_mq_poll_hybrid(struct request_queue *q,
3923 struct blk_mq_hw_ctx *hctx, blk_qc_t cookie)
3927 if (q->poll_nsec == BLK_MQ_POLL_CLASSIC)
3930 if (!blk_qc_t_is_internal(cookie))
3931 rq = blk_mq_tag_to_rq(hctx->tags, blk_qc_t_to_tag(cookie));
3933 rq = blk_mq_tag_to_rq(hctx->sched_tags, blk_qc_t_to_tag(cookie));
3935 * With scheduling, if the request has completed, we'll
3936 * get a NULL return here, as we clear the sched tag when
3937 * that happens. The request still remains valid, like always,
3938 * so we should be safe with just the NULL check.
3944 return blk_mq_poll_hybrid_sleep(q, rq);
3948 * blk_poll - poll for IO completions
3950 * @cookie: cookie passed back at IO submission time
3951 * @spin: whether to spin for completions
3954 * Poll for completions on the passed in queue. Returns number of
3955 * completed entries found. If @spin is true, then blk_poll will continue
3956 * looping until at least one completion is found, unless the task is
3957 * otherwise marked running (or we need to reschedule).
3959 int blk_poll(struct request_queue *q, blk_qc_t cookie, bool spin)
3961 struct blk_mq_hw_ctx *hctx;
3964 if (!blk_qc_t_valid(cookie) ||
3965 !test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
3969 blk_flush_plug_list(current->plug, false);
3971 hctx = q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)];
3974 * If we sleep, have the caller restart the poll loop to reset
3975 * the state. Like for the other success return cases, the
3976 * caller is responsible for checking if the IO completed. If
3977 * the IO isn't complete, we'll get called again and will go
3978 * straight to the busy poll loop. If specified not to spin,
3979 * we also should not sleep.
3981 if (spin && blk_mq_poll_hybrid(q, hctx, cookie))
3984 hctx->poll_considered++;
3986 state = get_current_state();
3990 hctx->poll_invoked++;
3992 ret = q->mq_ops->poll(hctx);
3994 hctx->poll_success++;
3995 __set_current_state(TASK_RUNNING);
3999 if (signal_pending_state(state, current))
4000 __set_current_state(TASK_RUNNING);
4002 if (task_is_running(current))
4004 if (ret < 0 || !spin)
4007 } while (!need_resched());
4009 __set_current_state(TASK_RUNNING);
4012 EXPORT_SYMBOL_GPL(blk_poll);
4014 unsigned int blk_mq_rq_cpu(struct request *rq)
4016 return rq->mq_ctx->cpu;
4018 EXPORT_SYMBOL(blk_mq_rq_cpu);
4020 void blk_mq_cancel_work_sync(struct request_queue *q)
4022 if (queue_is_mq(q)) {
4023 struct blk_mq_hw_ctx *hctx;
4026 cancel_delayed_work_sync(&q->requeue_work);
4028 queue_for_each_hw_ctx(q, hctx, i)
4029 cancel_delayed_work_sync(&hctx->run_work);
4033 static int __init blk_mq_init(void)
4037 for_each_possible_cpu(i)
4038 init_llist_head(&per_cpu(blk_cpu_done, i));
4039 open_softirq(BLOCK_SOFTIRQ, blk_done_softirq);
4041 cpuhp_setup_state_nocalls(CPUHP_BLOCK_SOFTIRQ_DEAD,
4042 "block/softirq:dead", NULL,
4043 blk_softirq_cpu_dead);
4044 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD, "block/mq:dead", NULL,
4045 blk_mq_hctx_notify_dead);
4046 cpuhp_setup_state_multi(CPUHP_AP_BLK_MQ_ONLINE, "block/mq:online",
4047 blk_mq_hctx_notify_online,
4048 blk_mq_hctx_notify_offline);
4051 subsys_initcall(blk_mq_init);