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_hw_ctx *hctx;
1648 * If the IO scheduler does not respect hardware queues when
1649 * dispatching, we just don't bother with multiple HW queues and
1650 * dispatch from hctx for the current CPU since running multiple queues
1651 * just causes lock contention inside the scheduler and pointless cache
1654 hctx = blk_mq_map_queue_type(q, HCTX_TYPE_DEFAULT,
1655 raw_smp_processor_id());
1656 if (!blk_mq_hctx_stopped(hctx))
1662 * blk_mq_run_hw_queues - Run all hardware queues in a request queue.
1663 * @q: Pointer to the request queue to run.
1664 * @async: If we want to run the queue asynchronously.
1666 void blk_mq_run_hw_queues(struct request_queue *q, bool async)
1668 struct blk_mq_hw_ctx *hctx, *sq_hctx;
1672 if (blk_mq_has_sqsched(q))
1673 sq_hctx = blk_mq_get_sq_hctx(q);
1674 queue_for_each_hw_ctx(q, hctx, i) {
1675 if (blk_mq_hctx_stopped(hctx))
1678 * Dispatch from this hctx either if there's no hctx preferred
1679 * by IO scheduler or if it has requests that bypass the
1682 if (!sq_hctx || sq_hctx == hctx ||
1683 !list_empty_careful(&hctx->dispatch))
1684 blk_mq_run_hw_queue(hctx, async);
1687 EXPORT_SYMBOL(blk_mq_run_hw_queues);
1690 * blk_mq_delay_run_hw_queues - Run all hardware queues asynchronously.
1691 * @q: Pointer to the request queue to run.
1692 * @msecs: Milliseconds of delay to wait before running the queues.
1694 void blk_mq_delay_run_hw_queues(struct request_queue *q, unsigned long msecs)
1696 struct blk_mq_hw_ctx *hctx, *sq_hctx;
1700 if (blk_mq_has_sqsched(q))
1701 sq_hctx = blk_mq_get_sq_hctx(q);
1702 queue_for_each_hw_ctx(q, hctx, i) {
1703 if (blk_mq_hctx_stopped(hctx))
1706 * Dispatch from this hctx either if there's no hctx preferred
1707 * by IO scheduler or if it has requests that bypass the
1710 if (!sq_hctx || sq_hctx == hctx ||
1711 !list_empty_careful(&hctx->dispatch))
1712 blk_mq_delay_run_hw_queue(hctx, msecs);
1715 EXPORT_SYMBOL(blk_mq_delay_run_hw_queues);
1718 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1719 * @q: request queue.
1721 * The caller is responsible for serializing this function against
1722 * blk_mq_{start,stop}_hw_queue().
1724 bool blk_mq_queue_stopped(struct request_queue *q)
1726 struct blk_mq_hw_ctx *hctx;
1729 queue_for_each_hw_ctx(q, hctx, i)
1730 if (blk_mq_hctx_stopped(hctx))
1735 EXPORT_SYMBOL(blk_mq_queue_stopped);
1738 * This function is often used for pausing .queue_rq() by driver when
1739 * there isn't enough resource or some conditions aren't satisfied, and
1740 * BLK_STS_RESOURCE is usually returned.
1742 * We do not guarantee that dispatch can be drained or blocked
1743 * after blk_mq_stop_hw_queue() returns. Please use
1744 * blk_mq_quiesce_queue() for that requirement.
1746 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
1748 cancel_delayed_work(&hctx->run_work);
1750 set_bit(BLK_MQ_S_STOPPED, &hctx->state);
1752 EXPORT_SYMBOL(blk_mq_stop_hw_queue);
1755 * This function is often used for pausing .queue_rq() by driver when
1756 * there isn't enough resource or some conditions aren't satisfied, and
1757 * BLK_STS_RESOURCE is usually returned.
1759 * We do not guarantee that dispatch can be drained or blocked
1760 * after blk_mq_stop_hw_queues() returns. Please use
1761 * blk_mq_quiesce_queue() for that requirement.
1763 void blk_mq_stop_hw_queues(struct request_queue *q)
1765 struct blk_mq_hw_ctx *hctx;
1768 queue_for_each_hw_ctx(q, hctx, i)
1769 blk_mq_stop_hw_queue(hctx);
1771 EXPORT_SYMBOL(blk_mq_stop_hw_queues);
1773 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
1775 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1777 blk_mq_run_hw_queue(hctx, false);
1779 EXPORT_SYMBOL(blk_mq_start_hw_queue);
1781 void blk_mq_start_hw_queues(struct request_queue *q)
1783 struct blk_mq_hw_ctx *hctx;
1786 queue_for_each_hw_ctx(q, hctx, i)
1787 blk_mq_start_hw_queue(hctx);
1789 EXPORT_SYMBOL(blk_mq_start_hw_queues);
1791 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
1793 if (!blk_mq_hctx_stopped(hctx))
1796 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1797 blk_mq_run_hw_queue(hctx, async);
1799 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue);
1801 void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async)
1803 struct blk_mq_hw_ctx *hctx;
1806 queue_for_each_hw_ctx(q, hctx, i)
1807 blk_mq_start_stopped_hw_queue(hctx, async);
1809 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);
1811 static void blk_mq_run_work_fn(struct work_struct *work)
1813 struct blk_mq_hw_ctx *hctx;
1815 hctx = container_of(work, struct blk_mq_hw_ctx, run_work.work);
1818 * If we are stopped, don't run the queue.
1820 if (blk_mq_hctx_stopped(hctx))
1823 __blk_mq_run_hw_queue(hctx);
1826 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx,
1830 struct blk_mq_ctx *ctx = rq->mq_ctx;
1831 enum hctx_type type = hctx->type;
1833 lockdep_assert_held(&ctx->lock);
1835 trace_block_rq_insert(rq);
1838 list_add(&rq->queuelist, &ctx->rq_lists[type]);
1840 list_add_tail(&rq->queuelist, &ctx->rq_lists[type]);
1843 void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
1846 struct blk_mq_ctx *ctx = rq->mq_ctx;
1848 lockdep_assert_held(&ctx->lock);
1850 __blk_mq_insert_req_list(hctx, rq, at_head);
1851 blk_mq_hctx_mark_pending(hctx, ctx);
1855 * blk_mq_request_bypass_insert - Insert a request at dispatch list.
1856 * @rq: Pointer to request to be inserted.
1857 * @at_head: true if the request should be inserted at the head of the list.
1858 * @run_queue: If we should run the hardware queue after inserting the request.
1860 * Should only be used carefully, when the caller knows we want to
1861 * bypass a potential IO scheduler on the target device.
1863 void blk_mq_request_bypass_insert(struct request *rq, bool at_head,
1866 struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
1868 spin_lock(&hctx->lock);
1870 list_add(&rq->queuelist, &hctx->dispatch);
1872 list_add_tail(&rq->queuelist, &hctx->dispatch);
1873 spin_unlock(&hctx->lock);
1876 blk_mq_run_hw_queue(hctx, false);
1879 void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
1880 struct list_head *list)
1884 enum hctx_type type = hctx->type;
1887 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1890 list_for_each_entry(rq, list, queuelist) {
1891 BUG_ON(rq->mq_ctx != ctx);
1892 trace_block_rq_insert(rq);
1895 spin_lock(&ctx->lock);
1896 list_splice_tail_init(list, &ctx->rq_lists[type]);
1897 blk_mq_hctx_mark_pending(hctx, ctx);
1898 spin_unlock(&ctx->lock);
1901 static int plug_rq_cmp(void *priv, const struct list_head *a,
1902 const struct list_head *b)
1904 struct request *rqa = container_of(a, struct request, queuelist);
1905 struct request *rqb = container_of(b, struct request, queuelist);
1907 if (rqa->mq_ctx != rqb->mq_ctx)
1908 return rqa->mq_ctx > rqb->mq_ctx;
1909 if (rqa->mq_hctx != rqb->mq_hctx)
1910 return rqa->mq_hctx > rqb->mq_hctx;
1912 return blk_rq_pos(rqa) > blk_rq_pos(rqb);
1915 void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
1919 if (list_empty(&plug->mq_list))
1921 list_splice_init(&plug->mq_list, &list);
1923 if (plug->rq_count > 2 && plug->multiple_queues)
1924 list_sort(NULL, &list, plug_rq_cmp);
1929 struct list_head rq_list;
1930 struct request *rq, *head_rq = list_entry_rq(list.next);
1931 struct list_head *pos = &head_rq->queuelist; /* skip first */
1932 struct blk_mq_hw_ctx *this_hctx = head_rq->mq_hctx;
1933 struct blk_mq_ctx *this_ctx = head_rq->mq_ctx;
1934 unsigned int depth = 1;
1936 list_for_each_continue(pos, &list) {
1937 rq = list_entry_rq(pos);
1939 if (rq->mq_hctx != this_hctx || rq->mq_ctx != this_ctx)
1944 list_cut_before(&rq_list, &list, pos);
1945 trace_block_unplug(head_rq->q, depth, !from_schedule);
1946 blk_mq_sched_insert_requests(this_hctx, this_ctx, &rq_list,
1948 } while(!list_empty(&list));
1951 static void blk_mq_bio_to_request(struct request *rq, struct bio *bio,
1952 unsigned int nr_segs)
1956 if (bio->bi_opf & REQ_RAHEAD)
1957 rq->cmd_flags |= REQ_FAILFAST_MASK;
1959 rq->__sector = bio->bi_iter.bi_sector;
1960 rq->write_hint = bio->bi_write_hint;
1961 blk_rq_bio_prep(rq, bio, nr_segs);
1963 /* This can't fail, since GFP_NOIO includes __GFP_DIRECT_RECLAIM. */
1964 err = blk_crypto_rq_bio_prep(rq, bio, GFP_NOIO);
1967 blk_account_io_start(rq);
1970 static blk_status_t __blk_mq_issue_directly(struct blk_mq_hw_ctx *hctx,
1972 blk_qc_t *cookie, bool last)
1974 struct request_queue *q = rq->q;
1975 struct blk_mq_queue_data bd = {
1979 blk_qc_t new_cookie;
1982 new_cookie = request_to_qc_t(hctx, rq);
1985 * For OK queue, we are done. For error, caller may kill it.
1986 * Any other error (busy), just add it to our list as we
1987 * previously would have done.
1989 ret = q->mq_ops->queue_rq(hctx, &bd);
1992 blk_mq_update_dispatch_busy(hctx, false);
1993 *cookie = new_cookie;
1995 case BLK_STS_RESOURCE:
1996 case BLK_STS_DEV_RESOURCE:
1997 blk_mq_update_dispatch_busy(hctx, true);
1998 __blk_mq_requeue_request(rq);
2001 blk_mq_update_dispatch_busy(hctx, false);
2002 *cookie = BLK_QC_T_NONE;
2009 static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
2012 bool bypass_insert, bool last)
2014 struct request_queue *q = rq->q;
2015 bool run_queue = true;
2019 * RCU or SRCU read lock is needed before checking quiesced flag.
2021 * When queue is stopped or quiesced, ignore 'bypass_insert' from
2022 * blk_mq_request_issue_directly(), and return BLK_STS_OK to caller,
2023 * and avoid driver to try to dispatch again.
2025 if (blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q)) {
2027 bypass_insert = false;
2031 if (q->elevator && !bypass_insert)
2034 budget_token = blk_mq_get_dispatch_budget(q);
2035 if (budget_token < 0)
2038 blk_mq_set_rq_budget_token(rq, budget_token);
2040 if (!blk_mq_get_driver_tag(rq)) {
2041 blk_mq_put_dispatch_budget(q, budget_token);
2045 return __blk_mq_issue_directly(hctx, rq, cookie, last);
2048 return BLK_STS_RESOURCE;
2050 blk_mq_sched_insert_request(rq, false, run_queue, false);
2056 * blk_mq_try_issue_directly - Try to send a request directly to device driver.
2057 * @hctx: Pointer of the associated hardware queue.
2058 * @rq: Pointer to request to be sent.
2059 * @cookie: Request queue cookie.
2061 * If the device has enough resources to accept a new request now, send the
2062 * request directly to device driver. Else, insert at hctx->dispatch queue, so
2063 * we can try send it another time in the future. Requests inserted at this
2064 * queue have higher priority.
2066 static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
2067 struct request *rq, blk_qc_t *cookie)
2072 might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
2074 hctx_lock(hctx, &srcu_idx);
2076 ret = __blk_mq_try_issue_directly(hctx, rq, cookie, false, true);
2077 if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE)
2078 blk_mq_request_bypass_insert(rq, false, true);
2079 else if (ret != BLK_STS_OK)
2080 blk_mq_end_request(rq, ret);
2082 hctx_unlock(hctx, srcu_idx);
2085 blk_status_t blk_mq_request_issue_directly(struct request *rq, bool last)
2089 blk_qc_t unused_cookie;
2090 struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
2092 hctx_lock(hctx, &srcu_idx);
2093 ret = __blk_mq_try_issue_directly(hctx, rq, &unused_cookie, true, last);
2094 hctx_unlock(hctx, srcu_idx);
2099 void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx,
2100 struct list_head *list)
2105 while (!list_empty(list)) {
2107 struct request *rq = list_first_entry(list, struct request,
2110 list_del_init(&rq->queuelist);
2111 ret = blk_mq_request_issue_directly(rq, list_empty(list));
2112 if (ret != BLK_STS_OK) {
2113 if (ret == BLK_STS_RESOURCE ||
2114 ret == BLK_STS_DEV_RESOURCE) {
2115 blk_mq_request_bypass_insert(rq, false,
2119 blk_mq_end_request(rq, ret);
2126 * If we didn't flush the entire list, we could have told
2127 * the driver there was more coming, but that turned out to
2130 if ((!list_empty(list) || errors) &&
2131 hctx->queue->mq_ops->commit_rqs && queued)
2132 hctx->queue->mq_ops->commit_rqs(hctx);
2135 static void blk_add_rq_to_plug(struct blk_plug *plug, struct request *rq)
2137 list_add_tail(&rq->queuelist, &plug->mq_list);
2139 if (!plug->multiple_queues && !list_is_singular(&plug->mq_list)) {
2140 struct request *tmp;
2142 tmp = list_first_entry(&plug->mq_list, struct request,
2144 if (tmp->q != rq->q)
2145 plug->multiple_queues = true;
2150 * Allow 2x BLK_MAX_REQUEST_COUNT requests on plug queue for multiple
2151 * queues. This is important for md arrays to benefit from merging
2154 static inline unsigned short blk_plug_max_rq_count(struct blk_plug *plug)
2156 if (plug->multiple_queues)
2157 return BLK_MAX_REQUEST_COUNT * 2;
2158 return BLK_MAX_REQUEST_COUNT;
2162 * blk_mq_submit_bio - Create and send a request to block device.
2163 * @bio: Bio pointer.
2165 * Builds up a request structure from @q and @bio and send to the device. The
2166 * request may not be queued directly to hardware if:
2167 * * This request can be merged with another one
2168 * * We want to place request at plug queue for possible future merging
2169 * * There is an IO scheduler active at this queue
2171 * It will not queue the request if there is an error with the bio, or at the
2174 * Returns: Request queue cookie.
2176 blk_qc_t blk_mq_submit_bio(struct bio *bio)
2178 struct request_queue *q = bio->bi_bdev->bd_disk->queue;
2179 const int is_sync = op_is_sync(bio->bi_opf);
2180 const int is_flush_fua = op_is_flush(bio->bi_opf);
2181 struct blk_mq_alloc_data data = {
2185 struct blk_plug *plug;
2186 struct request *same_queue_rq = NULL;
2187 unsigned int nr_segs;
2192 blk_queue_bounce(q, &bio);
2193 __blk_queue_split(&bio, &nr_segs);
2195 if (!bio_integrity_prep(bio))
2198 if (!is_flush_fua && !blk_queue_nomerges(q) &&
2199 blk_attempt_plug_merge(q, bio, nr_segs, &same_queue_rq))
2202 if (blk_mq_sched_bio_merge(q, bio, nr_segs))
2205 rq_qos_throttle(q, bio);
2207 hipri = bio->bi_opf & REQ_HIPRI;
2209 data.cmd_flags = bio->bi_opf;
2210 rq = __blk_mq_alloc_request(&data);
2211 if (unlikely(!rq)) {
2212 rq_qos_cleanup(q, bio);
2213 if (bio->bi_opf & REQ_NOWAIT)
2214 bio_wouldblock_error(bio);
2218 trace_block_getrq(bio);
2220 rq_qos_track(q, rq, bio);
2222 cookie = request_to_qc_t(data.hctx, rq);
2224 blk_mq_bio_to_request(rq, bio, nr_segs);
2226 ret = blk_crypto_init_request(rq);
2227 if (ret != BLK_STS_OK) {
2228 bio->bi_status = ret;
2230 blk_mq_free_request(rq);
2231 return BLK_QC_T_NONE;
2234 plug = blk_mq_plug(q, bio);
2235 if (unlikely(is_flush_fua)) {
2236 /* Bypass scheduler for flush requests */
2237 blk_insert_flush(rq);
2238 blk_mq_run_hw_queue(data.hctx, true);
2239 } else if (plug && (q->nr_hw_queues == 1 ||
2240 blk_mq_is_sbitmap_shared(rq->mq_hctx->flags) ||
2241 q->mq_ops->commit_rqs || !blk_queue_nonrot(q))) {
2243 * Use plugging if we have a ->commit_rqs() hook as well, as
2244 * we know the driver uses bd->last in a smart fashion.
2246 * Use normal plugging if this disk is slow HDD, as sequential
2247 * IO may benefit a lot from plug merging.
2249 unsigned int request_count = plug->rq_count;
2250 struct request *last = NULL;
2253 trace_block_plug(q);
2255 last = list_entry_rq(plug->mq_list.prev);
2257 if (request_count >= blk_plug_max_rq_count(plug) || (last &&
2258 blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
2259 blk_flush_plug_list(plug, false);
2260 trace_block_plug(q);
2263 blk_add_rq_to_plug(plug, rq);
2264 } else if (q->elevator) {
2265 /* Insert the request at the IO scheduler queue */
2266 blk_mq_sched_insert_request(rq, false, true, true);
2267 } else if (plug && !blk_queue_nomerges(q)) {
2269 * We do limited plugging. If the bio can be merged, do that.
2270 * Otherwise the existing request in the plug list will be
2271 * issued. So the plug list will have one request at most
2272 * The plug list might get flushed before this. If that happens,
2273 * the plug list is empty, and same_queue_rq is invalid.
2275 if (list_empty(&plug->mq_list))
2276 same_queue_rq = NULL;
2277 if (same_queue_rq) {
2278 list_del_init(&same_queue_rq->queuelist);
2281 blk_add_rq_to_plug(plug, rq);
2282 trace_block_plug(q);
2284 if (same_queue_rq) {
2285 data.hctx = same_queue_rq->mq_hctx;
2286 trace_block_unplug(q, 1, true);
2287 blk_mq_try_issue_directly(data.hctx, same_queue_rq,
2290 } else if ((q->nr_hw_queues > 1 && is_sync) ||
2291 !data.hctx->dispatch_busy) {
2293 * There is no scheduler and we can try to send directly
2296 blk_mq_try_issue_directly(data.hctx, rq, &cookie);
2299 blk_mq_sched_insert_request(rq, false, true, true);
2303 return BLK_QC_T_NONE;
2307 return BLK_QC_T_NONE;
2310 static size_t order_to_size(unsigned int order)
2312 return (size_t)PAGE_SIZE << order;
2315 /* called before freeing request pool in @tags */
2316 static void blk_mq_clear_rq_mapping(struct blk_mq_tag_set *set,
2317 struct blk_mq_tags *tags, unsigned int hctx_idx)
2319 struct blk_mq_tags *drv_tags = set->tags[hctx_idx];
2321 unsigned long flags;
2323 list_for_each_entry(page, &tags->page_list, lru) {
2324 unsigned long start = (unsigned long)page_address(page);
2325 unsigned long end = start + order_to_size(page->private);
2328 for (i = 0; i < set->queue_depth; i++) {
2329 struct request *rq = drv_tags->rqs[i];
2330 unsigned long rq_addr = (unsigned long)rq;
2332 if (rq_addr >= start && rq_addr < end) {
2333 WARN_ON_ONCE(refcount_read(&rq->ref) != 0);
2334 cmpxchg(&drv_tags->rqs[i], rq, NULL);
2340 * Wait until all pending iteration is done.
2342 * Request reference is cleared and it is guaranteed to be observed
2343 * after the ->lock is released.
2345 spin_lock_irqsave(&drv_tags->lock, flags);
2346 spin_unlock_irqrestore(&drv_tags->lock, flags);
2349 void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
2350 unsigned int hctx_idx)
2354 if (tags->rqs && set->ops->exit_request) {
2357 for (i = 0; i < tags->nr_tags; i++) {
2358 struct request *rq = tags->static_rqs[i];
2362 set->ops->exit_request(set, rq, hctx_idx);
2363 tags->static_rqs[i] = NULL;
2367 blk_mq_clear_rq_mapping(set, tags, hctx_idx);
2369 while (!list_empty(&tags->page_list)) {
2370 page = list_first_entry(&tags->page_list, struct page, lru);
2371 list_del_init(&page->lru);
2373 * Remove kmemleak object previously allocated in
2374 * blk_mq_alloc_rqs().
2376 kmemleak_free(page_address(page));
2377 __free_pages(page, page->private);
2381 void blk_mq_free_rq_map(struct blk_mq_tags *tags, unsigned int flags)
2385 kfree(tags->static_rqs);
2386 tags->static_rqs = NULL;
2388 blk_mq_free_tags(tags, flags);
2391 struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set,
2392 unsigned int hctx_idx,
2393 unsigned int nr_tags,
2394 unsigned int reserved_tags,
2397 struct blk_mq_tags *tags;
2400 node = blk_mq_hw_queue_to_node(&set->map[HCTX_TYPE_DEFAULT], hctx_idx);
2401 if (node == NUMA_NO_NODE)
2402 node = set->numa_node;
2404 tags = blk_mq_init_tags(nr_tags, reserved_tags, node, flags);
2408 tags->rqs = kcalloc_node(nr_tags, sizeof(struct request *),
2409 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
2412 blk_mq_free_tags(tags, flags);
2416 tags->static_rqs = kcalloc_node(nr_tags, sizeof(struct request *),
2417 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
2419 if (!tags->static_rqs) {
2421 blk_mq_free_tags(tags, flags);
2428 static int blk_mq_init_request(struct blk_mq_tag_set *set, struct request *rq,
2429 unsigned int hctx_idx, int node)
2433 if (set->ops->init_request) {
2434 ret = set->ops->init_request(set, rq, hctx_idx, node);
2439 WRITE_ONCE(rq->state, MQ_RQ_IDLE);
2443 int blk_mq_alloc_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
2444 unsigned int hctx_idx, unsigned int depth)
2446 unsigned int i, j, entries_per_page, max_order = 4;
2447 size_t rq_size, left;
2450 node = blk_mq_hw_queue_to_node(&set->map[HCTX_TYPE_DEFAULT], hctx_idx);
2451 if (node == NUMA_NO_NODE)
2452 node = set->numa_node;
2454 INIT_LIST_HEAD(&tags->page_list);
2457 * rq_size is the size of the request plus driver payload, rounded
2458 * to the cacheline size
2460 rq_size = round_up(sizeof(struct request) + set->cmd_size,
2462 left = rq_size * depth;
2464 for (i = 0; i < depth; ) {
2465 int this_order = max_order;
2470 while (this_order && left < order_to_size(this_order - 1))
2474 page = alloc_pages_node(node,
2475 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY | __GFP_ZERO,
2481 if (order_to_size(this_order) < rq_size)
2488 page->private = this_order;
2489 list_add_tail(&page->lru, &tags->page_list);
2491 p = page_address(page);
2493 * Allow kmemleak to scan these pages as they contain pointers
2494 * to additional allocations like via ops->init_request().
2496 kmemleak_alloc(p, order_to_size(this_order), 1, GFP_NOIO);
2497 entries_per_page = order_to_size(this_order) / rq_size;
2498 to_do = min(entries_per_page, depth - i);
2499 left -= to_do * rq_size;
2500 for (j = 0; j < to_do; j++) {
2501 struct request *rq = p;
2503 tags->static_rqs[i] = rq;
2504 if (blk_mq_init_request(set, rq, hctx_idx, node)) {
2505 tags->static_rqs[i] = NULL;
2516 blk_mq_free_rqs(set, tags, hctx_idx);
2520 struct rq_iter_data {
2521 struct blk_mq_hw_ctx *hctx;
2525 static bool blk_mq_has_request(struct request *rq, void *data, bool reserved)
2527 struct rq_iter_data *iter_data = data;
2529 if (rq->mq_hctx != iter_data->hctx)
2531 iter_data->has_rq = true;
2535 static bool blk_mq_hctx_has_requests(struct blk_mq_hw_ctx *hctx)
2537 struct blk_mq_tags *tags = hctx->sched_tags ?
2538 hctx->sched_tags : hctx->tags;
2539 struct rq_iter_data data = {
2543 blk_mq_all_tag_iter(tags, blk_mq_has_request, &data);
2547 static inline bool blk_mq_last_cpu_in_hctx(unsigned int cpu,
2548 struct blk_mq_hw_ctx *hctx)
2550 if (cpumask_next_and(-1, hctx->cpumask, cpu_online_mask) != cpu)
2552 if (cpumask_next_and(cpu, hctx->cpumask, cpu_online_mask) < nr_cpu_ids)
2557 static int blk_mq_hctx_notify_offline(unsigned int cpu, struct hlist_node *node)
2559 struct blk_mq_hw_ctx *hctx = hlist_entry_safe(node,
2560 struct blk_mq_hw_ctx, cpuhp_online);
2562 if (!cpumask_test_cpu(cpu, hctx->cpumask) ||
2563 !blk_mq_last_cpu_in_hctx(cpu, hctx))
2567 * Prevent new request from being allocated on the current hctx.
2569 * The smp_mb__after_atomic() Pairs with the implied barrier in
2570 * test_and_set_bit_lock in sbitmap_get(). Ensures the inactive flag is
2571 * seen once we return from the tag allocator.
2573 set_bit(BLK_MQ_S_INACTIVE, &hctx->state);
2574 smp_mb__after_atomic();
2577 * Try to grab a reference to the queue and wait for any outstanding
2578 * requests. If we could not grab a reference the queue has been
2579 * frozen and there are no requests.
2581 if (percpu_ref_tryget(&hctx->queue->q_usage_counter)) {
2582 while (blk_mq_hctx_has_requests(hctx))
2584 percpu_ref_put(&hctx->queue->q_usage_counter);
2590 static int blk_mq_hctx_notify_online(unsigned int cpu, struct hlist_node *node)
2592 struct blk_mq_hw_ctx *hctx = hlist_entry_safe(node,
2593 struct blk_mq_hw_ctx, cpuhp_online);
2595 if (cpumask_test_cpu(cpu, hctx->cpumask))
2596 clear_bit(BLK_MQ_S_INACTIVE, &hctx->state);
2601 * 'cpu' is going away. splice any existing rq_list entries from this
2602 * software queue to the hw queue dispatch list, and ensure that it
2605 static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node)
2607 struct blk_mq_hw_ctx *hctx;
2608 struct blk_mq_ctx *ctx;
2610 enum hctx_type type;
2612 hctx = hlist_entry_safe(node, struct blk_mq_hw_ctx, cpuhp_dead);
2613 if (!cpumask_test_cpu(cpu, hctx->cpumask))
2616 ctx = __blk_mq_get_ctx(hctx->queue, cpu);
2619 spin_lock(&ctx->lock);
2620 if (!list_empty(&ctx->rq_lists[type])) {
2621 list_splice_init(&ctx->rq_lists[type], &tmp);
2622 blk_mq_hctx_clear_pending(hctx, ctx);
2624 spin_unlock(&ctx->lock);
2626 if (list_empty(&tmp))
2629 spin_lock(&hctx->lock);
2630 list_splice_tail_init(&tmp, &hctx->dispatch);
2631 spin_unlock(&hctx->lock);
2633 blk_mq_run_hw_queue(hctx, true);
2637 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx *hctx)
2639 if (!(hctx->flags & BLK_MQ_F_STACKING))
2640 cpuhp_state_remove_instance_nocalls(CPUHP_AP_BLK_MQ_ONLINE,
2641 &hctx->cpuhp_online);
2642 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD,
2647 * Before freeing hw queue, clearing the flush request reference in
2648 * tags->rqs[] for avoiding potential UAF.
2650 static void blk_mq_clear_flush_rq_mapping(struct blk_mq_tags *tags,
2651 unsigned int queue_depth, struct request *flush_rq)
2654 unsigned long flags;
2656 /* The hw queue may not be mapped yet */
2660 WARN_ON_ONCE(refcount_read(&flush_rq->ref) != 0);
2662 for (i = 0; i < queue_depth; i++)
2663 cmpxchg(&tags->rqs[i], flush_rq, NULL);
2666 * Wait until all pending iteration is done.
2668 * Request reference is cleared and it is guaranteed to be observed
2669 * after the ->lock is released.
2671 spin_lock_irqsave(&tags->lock, flags);
2672 spin_unlock_irqrestore(&tags->lock, flags);
2675 /* hctx->ctxs will be freed in queue's release handler */
2676 static void blk_mq_exit_hctx(struct request_queue *q,
2677 struct blk_mq_tag_set *set,
2678 struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
2680 struct request *flush_rq = hctx->fq->flush_rq;
2682 if (blk_mq_hw_queue_mapped(hctx))
2683 blk_mq_tag_idle(hctx);
2685 blk_mq_clear_flush_rq_mapping(set->tags[hctx_idx],
2686 set->queue_depth, flush_rq);
2687 if (set->ops->exit_request)
2688 set->ops->exit_request(set, flush_rq, hctx_idx);
2690 if (set->ops->exit_hctx)
2691 set->ops->exit_hctx(hctx, hctx_idx);
2693 blk_mq_remove_cpuhp(hctx);
2695 spin_lock(&q->unused_hctx_lock);
2696 list_add(&hctx->hctx_list, &q->unused_hctx_list);
2697 spin_unlock(&q->unused_hctx_lock);
2700 static void blk_mq_exit_hw_queues(struct request_queue *q,
2701 struct blk_mq_tag_set *set, int nr_queue)
2703 struct blk_mq_hw_ctx *hctx;
2706 queue_for_each_hw_ctx(q, hctx, i) {
2709 blk_mq_debugfs_unregister_hctx(hctx);
2710 blk_mq_exit_hctx(q, set, hctx, i);
2714 static int blk_mq_hw_ctx_size(struct blk_mq_tag_set *tag_set)
2716 int hw_ctx_size = sizeof(struct blk_mq_hw_ctx);
2718 BUILD_BUG_ON(ALIGN(offsetof(struct blk_mq_hw_ctx, srcu),
2719 __alignof__(struct blk_mq_hw_ctx)) !=
2720 sizeof(struct blk_mq_hw_ctx));
2722 if (tag_set->flags & BLK_MQ_F_BLOCKING)
2723 hw_ctx_size += sizeof(struct srcu_struct);
2728 static int blk_mq_init_hctx(struct request_queue *q,
2729 struct blk_mq_tag_set *set,
2730 struct blk_mq_hw_ctx *hctx, unsigned hctx_idx)
2732 hctx->queue_num = hctx_idx;
2734 if (!(hctx->flags & BLK_MQ_F_STACKING))
2735 cpuhp_state_add_instance_nocalls(CPUHP_AP_BLK_MQ_ONLINE,
2736 &hctx->cpuhp_online);
2737 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD, &hctx->cpuhp_dead);
2739 hctx->tags = set->tags[hctx_idx];
2741 if (set->ops->init_hctx &&
2742 set->ops->init_hctx(hctx, set->driver_data, hctx_idx))
2743 goto unregister_cpu_notifier;
2745 if (blk_mq_init_request(set, hctx->fq->flush_rq, hctx_idx,
2751 if (set->ops->exit_hctx)
2752 set->ops->exit_hctx(hctx, hctx_idx);
2753 unregister_cpu_notifier:
2754 blk_mq_remove_cpuhp(hctx);
2758 static struct blk_mq_hw_ctx *
2759 blk_mq_alloc_hctx(struct request_queue *q, struct blk_mq_tag_set *set,
2762 struct blk_mq_hw_ctx *hctx;
2763 gfp_t gfp = GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY;
2765 hctx = kzalloc_node(blk_mq_hw_ctx_size(set), gfp, node);
2767 goto fail_alloc_hctx;
2769 if (!zalloc_cpumask_var_node(&hctx->cpumask, gfp, node))
2772 atomic_set(&hctx->nr_active, 0);
2773 if (node == NUMA_NO_NODE)
2774 node = set->numa_node;
2775 hctx->numa_node = node;
2777 INIT_DELAYED_WORK(&hctx->run_work, blk_mq_run_work_fn);
2778 spin_lock_init(&hctx->lock);
2779 INIT_LIST_HEAD(&hctx->dispatch);
2781 hctx->flags = set->flags & ~BLK_MQ_F_TAG_QUEUE_SHARED;
2783 INIT_LIST_HEAD(&hctx->hctx_list);
2786 * Allocate space for all possible cpus to avoid allocation at
2789 hctx->ctxs = kmalloc_array_node(nr_cpu_ids, sizeof(void *),
2794 if (sbitmap_init_node(&hctx->ctx_map, nr_cpu_ids, ilog2(8),
2795 gfp, node, false, false))
2799 spin_lock_init(&hctx->dispatch_wait_lock);
2800 init_waitqueue_func_entry(&hctx->dispatch_wait, blk_mq_dispatch_wake);
2801 INIT_LIST_HEAD(&hctx->dispatch_wait.entry);
2803 hctx->fq = blk_alloc_flush_queue(hctx->numa_node, set->cmd_size, gfp);
2807 if (hctx->flags & BLK_MQ_F_BLOCKING)
2808 init_srcu_struct(hctx->srcu);
2809 blk_mq_hctx_kobj_init(hctx);
2814 sbitmap_free(&hctx->ctx_map);
2818 free_cpumask_var(hctx->cpumask);
2825 static void blk_mq_init_cpu_queues(struct request_queue *q,
2826 unsigned int nr_hw_queues)
2828 struct blk_mq_tag_set *set = q->tag_set;
2831 for_each_possible_cpu(i) {
2832 struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
2833 struct blk_mq_hw_ctx *hctx;
2837 spin_lock_init(&__ctx->lock);
2838 for (k = HCTX_TYPE_DEFAULT; k < HCTX_MAX_TYPES; k++)
2839 INIT_LIST_HEAD(&__ctx->rq_lists[k]);
2844 * Set local node, IFF we have more than one hw queue. If
2845 * not, we remain on the home node of the device
2847 for (j = 0; j < set->nr_maps; j++) {
2848 hctx = blk_mq_map_queue_type(q, j, i);
2849 if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE)
2850 hctx->numa_node = cpu_to_node(i);
2855 static bool __blk_mq_alloc_map_and_request(struct blk_mq_tag_set *set,
2858 unsigned int flags = set->flags;
2861 set->tags[hctx_idx] = blk_mq_alloc_rq_map(set, hctx_idx,
2862 set->queue_depth, set->reserved_tags, flags);
2863 if (!set->tags[hctx_idx])
2866 ret = blk_mq_alloc_rqs(set, set->tags[hctx_idx], hctx_idx,
2871 blk_mq_free_rq_map(set->tags[hctx_idx], flags);
2872 set->tags[hctx_idx] = NULL;
2876 static void blk_mq_free_map_and_requests(struct blk_mq_tag_set *set,
2877 unsigned int hctx_idx)
2879 unsigned int flags = set->flags;
2881 if (set->tags && set->tags[hctx_idx]) {
2882 blk_mq_free_rqs(set, set->tags[hctx_idx], hctx_idx);
2883 blk_mq_free_rq_map(set->tags[hctx_idx], flags);
2884 set->tags[hctx_idx] = NULL;
2888 static void blk_mq_map_swqueue(struct request_queue *q)
2890 unsigned int i, j, hctx_idx;
2891 struct blk_mq_hw_ctx *hctx;
2892 struct blk_mq_ctx *ctx;
2893 struct blk_mq_tag_set *set = q->tag_set;
2895 queue_for_each_hw_ctx(q, hctx, i) {
2896 cpumask_clear(hctx->cpumask);
2898 hctx->dispatch_from = NULL;
2902 * Map software to hardware queues.
2904 * If the cpu isn't present, the cpu is mapped to first hctx.
2906 for_each_possible_cpu(i) {
2908 ctx = per_cpu_ptr(q->queue_ctx, i);
2909 for (j = 0; j < set->nr_maps; j++) {
2910 if (!set->map[j].nr_queues) {
2911 ctx->hctxs[j] = blk_mq_map_queue_type(q,
2912 HCTX_TYPE_DEFAULT, i);
2915 hctx_idx = set->map[j].mq_map[i];
2916 /* unmapped hw queue can be remapped after CPU topo changed */
2917 if (!set->tags[hctx_idx] &&
2918 !__blk_mq_alloc_map_and_request(set, hctx_idx)) {
2920 * If tags initialization fail for some hctx,
2921 * that hctx won't be brought online. In this
2922 * case, remap the current ctx to hctx[0] which
2923 * is guaranteed to always have tags allocated
2925 set->map[j].mq_map[i] = 0;
2928 hctx = blk_mq_map_queue_type(q, j, i);
2929 ctx->hctxs[j] = hctx;
2931 * If the CPU is already set in the mask, then we've
2932 * mapped this one already. This can happen if
2933 * devices share queues across queue maps.
2935 if (cpumask_test_cpu(i, hctx->cpumask))
2938 cpumask_set_cpu(i, hctx->cpumask);
2940 ctx->index_hw[hctx->type] = hctx->nr_ctx;
2941 hctx->ctxs[hctx->nr_ctx++] = ctx;
2944 * If the nr_ctx type overflows, we have exceeded the
2945 * amount of sw queues we can support.
2947 BUG_ON(!hctx->nr_ctx);
2950 for (; j < HCTX_MAX_TYPES; j++)
2951 ctx->hctxs[j] = blk_mq_map_queue_type(q,
2952 HCTX_TYPE_DEFAULT, i);
2955 queue_for_each_hw_ctx(q, hctx, i) {
2957 * If no software queues are mapped to this hardware queue,
2958 * disable it and free the request entries.
2960 if (!hctx->nr_ctx) {
2961 /* Never unmap queue 0. We need it as a
2962 * fallback in case of a new remap fails
2965 if (i && set->tags[i])
2966 blk_mq_free_map_and_requests(set, i);
2972 hctx->tags = set->tags[i];
2973 WARN_ON(!hctx->tags);
2976 * Set the map size to the number of mapped software queues.
2977 * This is more accurate and more efficient than looping
2978 * over all possibly mapped software queues.
2980 sbitmap_resize(&hctx->ctx_map, hctx->nr_ctx);
2983 * Initialize batch roundrobin counts
2985 hctx->next_cpu = blk_mq_first_mapped_cpu(hctx);
2986 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
2991 * Caller needs to ensure that we're either frozen/quiesced, or that
2992 * the queue isn't live yet.
2994 static void queue_set_hctx_shared(struct request_queue *q, bool shared)
2996 struct blk_mq_hw_ctx *hctx;
2999 queue_for_each_hw_ctx(q, hctx, i) {
3001 hctx->flags |= BLK_MQ_F_TAG_QUEUE_SHARED;
3003 blk_mq_tag_idle(hctx);
3004 hctx->flags &= ~BLK_MQ_F_TAG_QUEUE_SHARED;
3009 static void blk_mq_update_tag_set_shared(struct blk_mq_tag_set *set,
3012 struct request_queue *q;
3014 lockdep_assert_held(&set->tag_list_lock);
3016 list_for_each_entry(q, &set->tag_list, tag_set_list) {
3017 blk_mq_freeze_queue(q);
3018 queue_set_hctx_shared(q, shared);
3019 blk_mq_unfreeze_queue(q);
3023 static void blk_mq_del_queue_tag_set(struct request_queue *q)
3025 struct blk_mq_tag_set *set = q->tag_set;
3027 mutex_lock(&set->tag_list_lock);
3028 list_del(&q->tag_set_list);
3029 if (list_is_singular(&set->tag_list)) {
3030 /* just transitioned to unshared */
3031 set->flags &= ~BLK_MQ_F_TAG_QUEUE_SHARED;
3032 /* update existing queue */
3033 blk_mq_update_tag_set_shared(set, false);
3035 mutex_unlock(&set->tag_list_lock);
3036 INIT_LIST_HEAD(&q->tag_set_list);
3039 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
3040 struct request_queue *q)
3042 mutex_lock(&set->tag_list_lock);
3045 * Check to see if we're transitioning to shared (from 1 to 2 queues).
3047 if (!list_empty(&set->tag_list) &&
3048 !(set->flags & BLK_MQ_F_TAG_QUEUE_SHARED)) {
3049 set->flags |= BLK_MQ_F_TAG_QUEUE_SHARED;
3050 /* update existing queue */
3051 blk_mq_update_tag_set_shared(set, true);
3053 if (set->flags & BLK_MQ_F_TAG_QUEUE_SHARED)
3054 queue_set_hctx_shared(q, true);
3055 list_add_tail(&q->tag_set_list, &set->tag_list);
3057 mutex_unlock(&set->tag_list_lock);
3060 /* All allocations will be freed in release handler of q->mq_kobj */
3061 static int blk_mq_alloc_ctxs(struct request_queue *q)
3063 struct blk_mq_ctxs *ctxs;
3066 ctxs = kzalloc(sizeof(*ctxs), GFP_KERNEL);
3070 ctxs->queue_ctx = alloc_percpu(struct blk_mq_ctx);
3071 if (!ctxs->queue_ctx)
3074 for_each_possible_cpu(cpu) {
3075 struct blk_mq_ctx *ctx = per_cpu_ptr(ctxs->queue_ctx, cpu);
3079 q->mq_kobj = &ctxs->kobj;
3080 q->queue_ctx = ctxs->queue_ctx;
3089 * It is the actual release handler for mq, but we do it from
3090 * request queue's release handler for avoiding use-after-free
3091 * and headache because q->mq_kobj shouldn't have been introduced,
3092 * but we can't group ctx/kctx kobj without it.
3094 void blk_mq_release(struct request_queue *q)
3096 struct blk_mq_hw_ctx *hctx, *next;
3099 queue_for_each_hw_ctx(q, hctx, i)
3100 WARN_ON_ONCE(hctx && list_empty(&hctx->hctx_list));
3102 /* all hctx are in .unused_hctx_list now */
3103 list_for_each_entry_safe(hctx, next, &q->unused_hctx_list, hctx_list) {
3104 list_del_init(&hctx->hctx_list);
3105 kobject_put(&hctx->kobj);
3108 kfree(q->queue_hw_ctx);
3111 * release .mq_kobj and sw queue's kobject now because
3112 * both share lifetime with request queue.
3114 blk_mq_sysfs_deinit(q);
3117 static struct request_queue *blk_mq_init_queue_data(struct blk_mq_tag_set *set,
3120 struct request_queue *q;
3123 q = blk_alloc_queue(set->numa_node);
3125 return ERR_PTR(-ENOMEM);
3126 q->queuedata = queuedata;
3127 ret = blk_mq_init_allocated_queue(set, q);
3129 blk_cleanup_queue(q);
3130 return ERR_PTR(ret);
3135 struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
3137 return blk_mq_init_queue_data(set, NULL);
3139 EXPORT_SYMBOL(blk_mq_init_queue);
3141 struct gendisk *__blk_mq_alloc_disk(struct blk_mq_tag_set *set, void *queuedata,
3142 struct lock_class_key *lkclass)
3144 struct request_queue *q;
3145 struct gendisk *disk;
3147 q = blk_mq_init_queue_data(set, queuedata);
3151 disk = __alloc_disk_node(q, set->numa_node, lkclass);
3153 blk_cleanup_queue(q);
3154 return ERR_PTR(-ENOMEM);
3158 EXPORT_SYMBOL(__blk_mq_alloc_disk);
3160 static struct blk_mq_hw_ctx *blk_mq_alloc_and_init_hctx(
3161 struct blk_mq_tag_set *set, struct request_queue *q,
3162 int hctx_idx, int node)
3164 struct blk_mq_hw_ctx *hctx = NULL, *tmp;
3166 /* reuse dead hctx first */
3167 spin_lock(&q->unused_hctx_lock);
3168 list_for_each_entry(tmp, &q->unused_hctx_list, hctx_list) {
3169 if (tmp->numa_node == node) {
3175 list_del_init(&hctx->hctx_list);
3176 spin_unlock(&q->unused_hctx_lock);
3179 hctx = blk_mq_alloc_hctx(q, set, node);
3183 if (blk_mq_init_hctx(q, set, hctx, hctx_idx))
3189 kobject_put(&hctx->kobj);
3194 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
3195 struct request_queue *q)
3198 struct blk_mq_hw_ctx **hctxs = q->queue_hw_ctx;
3200 if (q->nr_hw_queues < set->nr_hw_queues) {
3201 struct blk_mq_hw_ctx **new_hctxs;
3203 new_hctxs = kcalloc_node(set->nr_hw_queues,
3204 sizeof(*new_hctxs), GFP_KERNEL,
3209 memcpy(new_hctxs, hctxs, q->nr_hw_queues *
3211 q->queue_hw_ctx = new_hctxs;
3216 /* protect against switching io scheduler */
3217 mutex_lock(&q->sysfs_lock);
3218 for (i = 0; i < set->nr_hw_queues; i++) {
3220 struct blk_mq_hw_ctx *hctx;
3222 node = blk_mq_hw_queue_to_node(&set->map[HCTX_TYPE_DEFAULT], i);
3224 * If the hw queue has been mapped to another numa node,
3225 * we need to realloc the hctx. If allocation fails, fallback
3226 * to use the previous one.
3228 if (hctxs[i] && (hctxs[i]->numa_node == node))
3231 hctx = blk_mq_alloc_and_init_hctx(set, q, i, node);
3234 blk_mq_exit_hctx(q, set, hctxs[i], i);
3238 pr_warn("Allocate new hctx on node %d fails,\
3239 fallback to previous one on node %d\n",
3240 node, hctxs[i]->numa_node);
3246 * Increasing nr_hw_queues fails. Free the newly allocated
3247 * hctxs and keep the previous q->nr_hw_queues.
3249 if (i != set->nr_hw_queues) {
3250 j = q->nr_hw_queues;
3254 end = q->nr_hw_queues;
3255 q->nr_hw_queues = set->nr_hw_queues;
3258 for (; j < end; j++) {
3259 struct blk_mq_hw_ctx *hctx = hctxs[j];
3263 blk_mq_free_map_and_requests(set, j);
3264 blk_mq_exit_hctx(q, set, hctx, j);
3268 mutex_unlock(&q->sysfs_lock);
3271 int blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
3272 struct request_queue *q)
3274 /* mark the queue as mq asap */
3275 q->mq_ops = set->ops;
3277 q->poll_cb = blk_stat_alloc_callback(blk_mq_poll_stats_fn,
3278 blk_mq_poll_stats_bkt,
3279 BLK_MQ_POLL_STATS_BKTS, q);
3283 if (blk_mq_alloc_ctxs(q))
3286 /* init q->mq_kobj and sw queues' kobjects */
3287 blk_mq_sysfs_init(q);
3289 INIT_LIST_HEAD(&q->unused_hctx_list);
3290 spin_lock_init(&q->unused_hctx_lock);
3292 blk_mq_realloc_hw_ctxs(set, q);
3293 if (!q->nr_hw_queues)
3296 INIT_WORK(&q->timeout_work, blk_mq_timeout_work);
3297 blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);
3301 q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
3302 if (set->nr_maps > HCTX_TYPE_POLL &&
3303 set->map[HCTX_TYPE_POLL].nr_queues)
3304 blk_queue_flag_set(QUEUE_FLAG_POLL, q);
3306 INIT_DELAYED_WORK(&q->requeue_work, blk_mq_requeue_work);
3307 INIT_LIST_HEAD(&q->requeue_list);
3308 spin_lock_init(&q->requeue_lock);
3310 q->nr_requests = set->queue_depth;
3313 * Default to classic polling
3315 q->poll_nsec = BLK_MQ_POLL_CLASSIC;
3317 blk_mq_init_cpu_queues(q, set->nr_hw_queues);
3318 blk_mq_add_queue_tag_set(set, q);
3319 blk_mq_map_swqueue(q);
3323 kfree(q->queue_hw_ctx);
3324 q->nr_hw_queues = 0;
3325 blk_mq_sysfs_deinit(q);
3327 blk_stat_free_callback(q->poll_cb);
3333 EXPORT_SYMBOL(blk_mq_init_allocated_queue);
3335 /* tags can _not_ be used after returning from blk_mq_exit_queue */
3336 void blk_mq_exit_queue(struct request_queue *q)
3338 struct blk_mq_tag_set *set = q->tag_set;
3340 /* Checks hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED. */
3341 blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
3342 /* May clear BLK_MQ_F_TAG_QUEUE_SHARED in hctx->flags. */
3343 blk_mq_del_queue_tag_set(q);
3346 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
3350 for (i = 0; i < set->nr_hw_queues; i++) {
3351 if (!__blk_mq_alloc_map_and_request(set, i))
3360 blk_mq_free_map_and_requests(set, i);
3366 * Allocate the request maps associated with this tag_set. Note that this
3367 * may reduce the depth asked for, if memory is tight. set->queue_depth
3368 * will be updated to reflect the allocated depth.
3370 static int blk_mq_alloc_map_and_requests(struct blk_mq_tag_set *set)
3375 depth = set->queue_depth;
3377 err = __blk_mq_alloc_rq_maps(set);
3381 set->queue_depth >>= 1;
3382 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN) {
3386 } while (set->queue_depth);
3388 if (!set->queue_depth || err) {
3389 pr_err("blk-mq: failed to allocate request map\n");
3393 if (depth != set->queue_depth)
3394 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
3395 depth, set->queue_depth);
3400 static int blk_mq_update_queue_map(struct blk_mq_tag_set *set)
3403 * blk_mq_map_queues() and multiple .map_queues() implementations
3404 * expect that set->map[HCTX_TYPE_DEFAULT].nr_queues is set to the
3405 * number of hardware queues.
3407 if (set->nr_maps == 1)
3408 set->map[HCTX_TYPE_DEFAULT].nr_queues = set->nr_hw_queues;
3410 if (set->ops->map_queues && !is_kdump_kernel()) {
3414 * transport .map_queues is usually done in the following
3417 * for (queue = 0; queue < set->nr_hw_queues; queue++) {
3418 * mask = get_cpu_mask(queue)
3419 * for_each_cpu(cpu, mask)
3420 * set->map[x].mq_map[cpu] = queue;
3423 * When we need to remap, the table has to be cleared for
3424 * killing stale mapping since one CPU may not be mapped
3427 for (i = 0; i < set->nr_maps; i++)
3428 blk_mq_clear_mq_map(&set->map[i]);
3430 return set->ops->map_queues(set);
3432 BUG_ON(set->nr_maps > 1);
3433 return blk_mq_map_queues(&set->map[HCTX_TYPE_DEFAULT]);
3437 static int blk_mq_realloc_tag_set_tags(struct blk_mq_tag_set *set,
3438 int cur_nr_hw_queues, int new_nr_hw_queues)
3440 struct blk_mq_tags **new_tags;
3442 if (cur_nr_hw_queues >= new_nr_hw_queues)
3445 new_tags = kcalloc_node(new_nr_hw_queues, sizeof(struct blk_mq_tags *),
3446 GFP_KERNEL, set->numa_node);
3451 memcpy(new_tags, set->tags, cur_nr_hw_queues *
3452 sizeof(*set->tags));
3454 set->tags = new_tags;
3455 set->nr_hw_queues = new_nr_hw_queues;
3460 static int blk_mq_alloc_tag_set_tags(struct blk_mq_tag_set *set,
3461 int new_nr_hw_queues)
3463 return blk_mq_realloc_tag_set_tags(set, 0, new_nr_hw_queues);
3467 * Alloc a tag set to be associated with one or more request queues.
3468 * May fail with EINVAL for various error conditions. May adjust the
3469 * requested depth down, if it's too large. In that case, the set
3470 * value will be stored in set->queue_depth.
3472 int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
3476 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH > 1 << BLK_MQ_UNIQUE_TAG_BITS);
3478 if (!set->nr_hw_queues)
3480 if (!set->queue_depth)
3482 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN)
3485 if (!set->ops->queue_rq)
3488 if (!set->ops->get_budget ^ !set->ops->put_budget)
3491 if (set->queue_depth > BLK_MQ_MAX_DEPTH) {
3492 pr_info("blk-mq: reduced tag depth to %u\n",
3494 set->queue_depth = BLK_MQ_MAX_DEPTH;
3499 else if (set->nr_maps > HCTX_MAX_TYPES)
3503 * If a crashdump is active, then we are potentially in a very
3504 * memory constrained environment. Limit us to 1 queue and
3505 * 64 tags to prevent using too much memory.
3507 if (is_kdump_kernel()) {
3508 set->nr_hw_queues = 1;
3510 set->queue_depth = min(64U, set->queue_depth);
3513 * There is no use for more h/w queues than cpus if we just have
3516 if (set->nr_maps == 1 && set->nr_hw_queues > nr_cpu_ids)
3517 set->nr_hw_queues = nr_cpu_ids;
3519 if (blk_mq_alloc_tag_set_tags(set, set->nr_hw_queues) < 0)
3523 for (i = 0; i < set->nr_maps; i++) {
3524 set->map[i].mq_map = kcalloc_node(nr_cpu_ids,
3525 sizeof(set->map[i].mq_map[0]),
3526 GFP_KERNEL, set->numa_node);
3527 if (!set->map[i].mq_map)
3528 goto out_free_mq_map;
3529 set->map[i].nr_queues = is_kdump_kernel() ? 1 : set->nr_hw_queues;
3532 ret = blk_mq_update_queue_map(set);
3534 goto out_free_mq_map;
3536 ret = blk_mq_alloc_map_and_requests(set);
3538 goto out_free_mq_map;
3540 if (blk_mq_is_sbitmap_shared(set->flags)) {
3541 atomic_set(&set->active_queues_shared_sbitmap, 0);
3543 if (blk_mq_init_shared_sbitmap(set)) {
3545 goto out_free_mq_rq_maps;
3549 mutex_init(&set->tag_list_lock);
3550 INIT_LIST_HEAD(&set->tag_list);
3554 out_free_mq_rq_maps:
3555 for (i = 0; i < set->nr_hw_queues; i++)
3556 blk_mq_free_map_and_requests(set, i);
3558 for (i = 0; i < set->nr_maps; i++) {
3559 kfree(set->map[i].mq_map);
3560 set->map[i].mq_map = NULL;
3566 EXPORT_SYMBOL(blk_mq_alloc_tag_set);
3568 /* allocate and initialize a tagset for a simple single-queue device */
3569 int blk_mq_alloc_sq_tag_set(struct blk_mq_tag_set *set,
3570 const struct blk_mq_ops *ops, unsigned int queue_depth,
3571 unsigned int set_flags)
3573 memset(set, 0, sizeof(*set));
3575 set->nr_hw_queues = 1;
3577 set->queue_depth = queue_depth;
3578 set->numa_node = NUMA_NO_NODE;
3579 set->flags = set_flags;
3580 return blk_mq_alloc_tag_set(set);
3582 EXPORT_SYMBOL_GPL(blk_mq_alloc_sq_tag_set);
3584 void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
3588 for (i = 0; i < set->nr_hw_queues; i++)
3589 blk_mq_free_map_and_requests(set, i);
3591 if (blk_mq_is_sbitmap_shared(set->flags))
3592 blk_mq_exit_shared_sbitmap(set);
3594 for (j = 0; j < set->nr_maps; j++) {
3595 kfree(set->map[j].mq_map);
3596 set->map[j].mq_map = NULL;
3602 EXPORT_SYMBOL(blk_mq_free_tag_set);
3604 int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
3606 struct blk_mq_tag_set *set = q->tag_set;
3607 struct blk_mq_hw_ctx *hctx;
3613 if (q->nr_requests == nr)
3616 blk_mq_freeze_queue(q);
3617 blk_mq_quiesce_queue(q);
3620 queue_for_each_hw_ctx(q, hctx, i) {
3624 * If we're using an MQ scheduler, just update the scheduler
3625 * queue depth. This is similar to what the old code would do.
3627 if (!hctx->sched_tags) {
3628 ret = blk_mq_tag_update_depth(hctx, &hctx->tags, nr,
3630 if (!ret && blk_mq_is_sbitmap_shared(set->flags))
3631 blk_mq_tag_resize_shared_sbitmap(set, nr);
3633 ret = blk_mq_tag_update_depth(hctx, &hctx->sched_tags,
3635 if (blk_mq_is_sbitmap_shared(set->flags)) {
3636 hctx->sched_tags->bitmap_tags =
3637 &q->sched_bitmap_tags;
3638 hctx->sched_tags->breserved_tags =
3639 &q->sched_breserved_tags;
3644 if (q->elevator && q->elevator->type->ops.depth_updated)
3645 q->elevator->type->ops.depth_updated(hctx);
3648 q->nr_requests = nr;
3649 if (q->elevator && blk_mq_is_sbitmap_shared(set->flags))
3650 sbitmap_queue_resize(&q->sched_bitmap_tags,
3651 nr - set->reserved_tags);
3654 blk_mq_unquiesce_queue(q);
3655 blk_mq_unfreeze_queue(q);
3661 * request_queue and elevator_type pair.
3662 * It is just used by __blk_mq_update_nr_hw_queues to cache
3663 * the elevator_type associated with a request_queue.
3665 struct blk_mq_qe_pair {
3666 struct list_head node;
3667 struct request_queue *q;
3668 struct elevator_type *type;
3672 * Cache the elevator_type in qe pair list and switch the
3673 * io scheduler to 'none'
3675 static bool blk_mq_elv_switch_none(struct list_head *head,
3676 struct request_queue *q)
3678 struct blk_mq_qe_pair *qe;
3683 qe = kmalloc(sizeof(*qe), GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY);
3687 INIT_LIST_HEAD(&qe->node);
3689 qe->type = q->elevator->type;
3690 list_add(&qe->node, head);
3692 mutex_lock(&q->sysfs_lock);
3694 * After elevator_switch_mq, the previous elevator_queue will be
3695 * released by elevator_release. The reference of the io scheduler
3696 * module get by elevator_get will also be put. So we need to get
3697 * a reference of the io scheduler module here to prevent it to be
3700 __module_get(qe->type->elevator_owner);
3701 elevator_switch_mq(q, NULL);
3702 mutex_unlock(&q->sysfs_lock);
3707 static void blk_mq_elv_switch_back(struct list_head *head,
3708 struct request_queue *q)
3710 struct blk_mq_qe_pair *qe;
3711 struct elevator_type *t = NULL;
3713 list_for_each_entry(qe, head, node)
3722 list_del(&qe->node);
3725 mutex_lock(&q->sysfs_lock);
3726 elevator_switch_mq(q, t);
3727 mutex_unlock(&q->sysfs_lock);
3730 static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set,
3733 struct request_queue *q;
3735 int prev_nr_hw_queues;
3737 lockdep_assert_held(&set->tag_list_lock);
3739 if (set->nr_maps == 1 && nr_hw_queues > nr_cpu_ids)
3740 nr_hw_queues = nr_cpu_ids;
3741 if (nr_hw_queues < 1)
3743 if (set->nr_maps == 1 && nr_hw_queues == set->nr_hw_queues)
3746 list_for_each_entry(q, &set->tag_list, tag_set_list)
3747 blk_mq_freeze_queue(q);
3749 * Switch IO scheduler to 'none', cleaning up the data associated
3750 * with the previous scheduler. We will switch back once we are done
3751 * updating the new sw to hw queue mappings.
3753 list_for_each_entry(q, &set->tag_list, tag_set_list)
3754 if (!blk_mq_elv_switch_none(&head, q))
3757 list_for_each_entry(q, &set->tag_list, tag_set_list) {
3758 blk_mq_debugfs_unregister_hctxs(q);
3759 blk_mq_sysfs_unregister(q);
3762 prev_nr_hw_queues = set->nr_hw_queues;
3763 if (blk_mq_realloc_tag_set_tags(set, set->nr_hw_queues, nr_hw_queues) <
3767 set->nr_hw_queues = nr_hw_queues;
3769 blk_mq_update_queue_map(set);
3770 list_for_each_entry(q, &set->tag_list, tag_set_list) {
3771 blk_mq_realloc_hw_ctxs(set, q);
3772 if (q->nr_hw_queues != set->nr_hw_queues) {
3773 pr_warn("Increasing nr_hw_queues to %d fails, fallback to %d\n",
3774 nr_hw_queues, prev_nr_hw_queues);
3775 set->nr_hw_queues = prev_nr_hw_queues;
3776 blk_mq_map_queues(&set->map[HCTX_TYPE_DEFAULT]);
3779 blk_mq_map_swqueue(q);
3783 list_for_each_entry(q, &set->tag_list, tag_set_list) {
3784 blk_mq_sysfs_register(q);
3785 blk_mq_debugfs_register_hctxs(q);
3789 list_for_each_entry(q, &set->tag_list, tag_set_list)
3790 blk_mq_elv_switch_back(&head, q);
3792 list_for_each_entry(q, &set->tag_list, tag_set_list)
3793 blk_mq_unfreeze_queue(q);
3796 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
3798 mutex_lock(&set->tag_list_lock);
3799 __blk_mq_update_nr_hw_queues(set, nr_hw_queues);
3800 mutex_unlock(&set->tag_list_lock);
3802 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues);
3804 /* Enable polling stats and return whether they were already enabled. */
3805 static bool blk_poll_stats_enable(struct request_queue *q)
3807 if (test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
3808 blk_queue_flag_test_and_set(QUEUE_FLAG_POLL_STATS, q))
3810 blk_stat_add_callback(q, q->poll_cb);
3814 static void blk_mq_poll_stats_start(struct request_queue *q)
3817 * We don't arm the callback if polling stats are not enabled or the
3818 * callback is already active.
3820 if (!test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
3821 blk_stat_is_active(q->poll_cb))
3824 blk_stat_activate_msecs(q->poll_cb, 100);
3827 static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb)
3829 struct request_queue *q = cb->data;
3832 for (bucket = 0; bucket < BLK_MQ_POLL_STATS_BKTS; bucket++) {
3833 if (cb->stat[bucket].nr_samples)
3834 q->poll_stat[bucket] = cb->stat[bucket];
3838 static unsigned long blk_mq_poll_nsecs(struct request_queue *q,
3841 unsigned long ret = 0;
3845 * If stats collection isn't on, don't sleep but turn it on for
3848 if (!blk_poll_stats_enable(q))
3852 * As an optimistic guess, use half of the mean service time
3853 * for this type of request. We can (and should) make this smarter.
3854 * For instance, if the completion latencies are tight, we can
3855 * get closer than just half the mean. This is especially
3856 * important on devices where the completion latencies are longer
3857 * than ~10 usec. We do use the stats for the relevant IO size
3858 * if available which does lead to better estimates.
3860 bucket = blk_mq_poll_stats_bkt(rq);
3864 if (q->poll_stat[bucket].nr_samples)
3865 ret = (q->poll_stat[bucket].mean + 1) / 2;
3870 static bool blk_mq_poll_hybrid_sleep(struct request_queue *q,
3873 struct hrtimer_sleeper hs;
3874 enum hrtimer_mode mode;
3878 if (rq->rq_flags & RQF_MQ_POLL_SLEPT)
3882 * If we get here, hybrid polling is enabled. Hence poll_nsec can be:
3884 * 0: use half of prev avg
3885 * >0: use this specific value
3887 if (q->poll_nsec > 0)
3888 nsecs = q->poll_nsec;
3890 nsecs = blk_mq_poll_nsecs(q, rq);
3895 rq->rq_flags |= RQF_MQ_POLL_SLEPT;
3898 * This will be replaced with the stats tracking code, using
3899 * 'avg_completion_time / 2' as the pre-sleep target.
3903 mode = HRTIMER_MODE_REL;
3904 hrtimer_init_sleeper_on_stack(&hs, CLOCK_MONOTONIC, mode);
3905 hrtimer_set_expires(&hs.timer, kt);
3908 if (blk_mq_rq_state(rq) == MQ_RQ_COMPLETE)
3910 set_current_state(TASK_UNINTERRUPTIBLE);
3911 hrtimer_sleeper_start_expires(&hs, mode);
3914 hrtimer_cancel(&hs.timer);
3915 mode = HRTIMER_MODE_ABS;
3916 } while (hs.task && !signal_pending(current));
3918 __set_current_state(TASK_RUNNING);
3919 destroy_hrtimer_on_stack(&hs.timer);
3923 static bool blk_mq_poll_hybrid(struct request_queue *q,
3924 struct blk_mq_hw_ctx *hctx, blk_qc_t cookie)
3928 if (q->poll_nsec == BLK_MQ_POLL_CLASSIC)
3931 if (!blk_qc_t_is_internal(cookie))
3932 rq = blk_mq_tag_to_rq(hctx->tags, blk_qc_t_to_tag(cookie));
3934 rq = blk_mq_tag_to_rq(hctx->sched_tags, blk_qc_t_to_tag(cookie));
3936 * With scheduling, if the request has completed, we'll
3937 * get a NULL return here, as we clear the sched tag when
3938 * that happens. The request still remains valid, like always,
3939 * so we should be safe with just the NULL check.
3945 return blk_mq_poll_hybrid_sleep(q, rq);
3949 * blk_poll - poll for IO completions
3951 * @cookie: cookie passed back at IO submission time
3952 * @spin: whether to spin for completions
3955 * Poll for completions on the passed in queue. Returns number of
3956 * completed entries found. If @spin is true, then blk_poll will continue
3957 * looping until at least one completion is found, unless the task is
3958 * otherwise marked running (or we need to reschedule).
3960 int blk_poll(struct request_queue *q, blk_qc_t cookie, bool spin)
3962 struct blk_mq_hw_ctx *hctx;
3965 if (!blk_qc_t_valid(cookie) ||
3966 !test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
3970 blk_flush_plug_list(current->plug, false);
3972 hctx = q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)];
3975 * If we sleep, have the caller restart the poll loop to reset
3976 * the state. Like for the other success return cases, the
3977 * caller is responsible for checking if the IO completed. If
3978 * the IO isn't complete, we'll get called again and will go
3979 * straight to the busy poll loop. If specified not to spin,
3980 * we also should not sleep.
3982 if (spin && blk_mq_poll_hybrid(q, hctx, cookie))
3985 hctx->poll_considered++;
3987 state = get_current_state();
3991 hctx->poll_invoked++;
3993 ret = q->mq_ops->poll(hctx);
3995 hctx->poll_success++;
3996 __set_current_state(TASK_RUNNING);
4000 if (signal_pending_state(state, current))
4001 __set_current_state(TASK_RUNNING);
4003 if (task_is_running(current))
4005 if (ret < 0 || !spin)
4008 } while (!need_resched());
4010 __set_current_state(TASK_RUNNING);
4013 EXPORT_SYMBOL_GPL(blk_poll);
4015 unsigned int blk_mq_rq_cpu(struct request *rq)
4017 return rq->mq_ctx->cpu;
4019 EXPORT_SYMBOL(blk_mq_rq_cpu);
4021 void blk_mq_cancel_work_sync(struct request_queue *q)
4023 if (queue_is_mq(q)) {
4024 struct blk_mq_hw_ctx *hctx;
4027 cancel_delayed_work_sync(&q->requeue_work);
4029 queue_for_each_hw_ctx(q, hctx, i)
4030 cancel_delayed_work_sync(&hctx->run_work);
4034 static int __init blk_mq_init(void)
4038 for_each_possible_cpu(i)
4039 init_llist_head(&per_cpu(blk_cpu_done, i));
4040 open_softirq(BLOCK_SOFTIRQ, blk_done_softirq);
4042 cpuhp_setup_state_nocalls(CPUHP_BLOCK_SOFTIRQ_DEAD,
4043 "block/softirq:dead", NULL,
4044 blk_softirq_cpu_dead);
4045 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD, "block/mq:dead", NULL,
4046 blk_mq_hctx_notify_dead);
4047 cpuhp_setup_state_multi(CPUHP_AP_BLK_MQ_ONLINE, "block/mq:online",
4048 blk_mq_hctx_notify_online,
4049 blk_mq_hctx_notify_offline);
4052 subsys_initcall(blk_mq_init);