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 list_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)
193 mutex_lock(&q->mq_freeze_lock);
194 q->mq_freeze_depth--;
195 WARN_ON_ONCE(q->mq_freeze_depth < 0);
196 if (!q->mq_freeze_depth) {
197 percpu_ref_resurrect(&q->q_usage_counter);
198 wake_up_all(&q->mq_freeze_wq);
200 mutex_unlock(&q->mq_freeze_lock);
202 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue);
205 * FIXME: replace the scsi_internal_device_*block_nowait() calls in the
206 * mpt3sas driver such that this function can be removed.
208 void blk_mq_quiesce_queue_nowait(struct request_queue *q)
210 blk_queue_flag_set(QUEUE_FLAG_QUIESCED, q);
212 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait);
215 * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished
218 * Note: this function does not prevent that the struct request end_io()
219 * callback function is invoked. Once this function is returned, we make
220 * sure no dispatch can happen until the queue is unquiesced via
221 * blk_mq_unquiesce_queue().
223 void blk_mq_quiesce_queue(struct request_queue *q)
225 struct blk_mq_hw_ctx *hctx;
229 blk_mq_quiesce_queue_nowait(q);
231 queue_for_each_hw_ctx(q, hctx, i) {
232 if (hctx->flags & BLK_MQ_F_BLOCKING)
233 synchronize_srcu(hctx->srcu);
240 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue);
243 * blk_mq_unquiesce_queue() - counterpart of blk_mq_quiesce_queue()
246 * This function recovers queue into the state before quiescing
247 * which is done by blk_mq_quiesce_queue.
249 void blk_mq_unquiesce_queue(struct request_queue *q)
251 blk_queue_flag_clear(QUEUE_FLAG_QUIESCED, q);
253 /* dispatch requests which are inserted during quiescing */
254 blk_mq_run_hw_queues(q, true);
256 EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue);
258 void blk_mq_wake_waiters(struct request_queue *q)
260 struct blk_mq_hw_ctx *hctx;
263 queue_for_each_hw_ctx(q, hctx, i)
264 if (blk_mq_hw_queue_mapped(hctx))
265 blk_mq_tag_wakeup_all(hctx->tags, true);
269 * Only need start/end time stamping if we have iostat or
270 * blk stats enabled, or using an IO scheduler.
272 static inline bool blk_mq_need_time_stamp(struct request *rq)
274 return (rq->rq_flags & (RQF_IO_STAT | RQF_STATS)) || rq->q->elevator;
277 static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
278 unsigned int tag, u64 alloc_time_ns)
280 struct blk_mq_tags *tags = blk_mq_tags_from_data(data);
281 struct request *rq = tags->static_rqs[tag];
283 if (data->q->elevator) {
284 rq->tag = BLK_MQ_NO_TAG;
285 rq->internal_tag = tag;
288 rq->internal_tag = BLK_MQ_NO_TAG;
291 /* csd/requeue_work/fifo_time is initialized before use */
293 rq->mq_ctx = data->ctx;
294 rq->mq_hctx = data->hctx;
296 rq->cmd_flags = data->cmd_flags;
297 if (data->flags & BLK_MQ_REQ_PREEMPT)
298 rq->rq_flags |= RQF_PREEMPT;
299 if (blk_queue_io_stat(data->q))
300 rq->rq_flags |= RQF_IO_STAT;
301 INIT_LIST_HEAD(&rq->queuelist);
302 INIT_HLIST_NODE(&rq->hash);
303 RB_CLEAR_NODE(&rq->rb_node);
306 #ifdef CONFIG_BLK_RQ_ALLOC_TIME
307 rq->alloc_time_ns = alloc_time_ns;
309 if (blk_mq_need_time_stamp(rq))
310 rq->start_time_ns = ktime_get_ns();
312 rq->start_time_ns = 0;
313 rq->io_start_time_ns = 0;
314 rq->stats_sectors = 0;
315 rq->nr_phys_segments = 0;
316 #if defined(CONFIG_BLK_DEV_INTEGRITY)
317 rq->nr_integrity_segments = 0;
319 blk_crypto_rq_set_defaults(rq);
320 /* tag was already set */
321 WRITE_ONCE(rq->deadline, 0);
326 rq->end_io_data = NULL;
328 data->ctx->rq_dispatched[op_is_sync(data->cmd_flags)]++;
329 refcount_set(&rq->ref, 1);
331 if (!op_is_flush(data->cmd_flags)) {
332 struct elevator_queue *e = data->q->elevator;
335 if (e && e->type->ops.prepare_request) {
336 if (e->type->icq_cache)
337 blk_mq_sched_assign_ioc(rq);
339 e->type->ops.prepare_request(rq);
340 rq->rq_flags |= RQF_ELVPRIV;
344 data->hctx->queued++;
348 static struct request *__blk_mq_alloc_request(struct blk_mq_alloc_data *data)
350 struct request_queue *q = data->q;
351 struct elevator_queue *e = q->elevator;
352 u64 alloc_time_ns = 0;
355 /* alloc_time includes depth and tag waits */
356 if (blk_queue_rq_alloc_time(q))
357 alloc_time_ns = ktime_get_ns();
359 if (data->cmd_flags & REQ_NOWAIT)
360 data->flags |= BLK_MQ_REQ_NOWAIT;
364 * Flush requests are special and go directly to the
365 * dispatch list. Don't include reserved tags in the
366 * limiting, as it isn't useful.
368 if (!op_is_flush(data->cmd_flags) &&
369 e->type->ops.limit_depth &&
370 !(data->flags & BLK_MQ_REQ_RESERVED))
371 e->type->ops.limit_depth(data->cmd_flags, data);
375 data->ctx = blk_mq_get_ctx(q);
376 data->hctx = blk_mq_map_queue(q, data->cmd_flags, data->ctx);
378 blk_mq_tag_busy(data->hctx);
381 * Waiting allocations only fail because of an inactive hctx. In that
382 * case just retry the hctx assignment and tag allocation as CPU hotplug
383 * should have migrated us to an online CPU by now.
385 tag = blk_mq_get_tag(data);
386 if (tag == BLK_MQ_NO_TAG) {
387 if (data->flags & BLK_MQ_REQ_NOWAIT)
391 * Give up the CPU and sleep for a random short time to ensure
392 * that thread using a realtime scheduling class are migrated
393 * off the CPU, and thus off the hctx that is going away.
398 return blk_mq_rq_ctx_init(data, tag, alloc_time_ns);
401 struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op,
402 blk_mq_req_flags_t flags)
404 struct blk_mq_alloc_data data = {
412 ret = blk_queue_enter(q, flags);
416 rq = __blk_mq_alloc_request(&data);
420 rq->__sector = (sector_t) -1;
421 rq->bio = rq->biotail = NULL;
425 return ERR_PTR(-EWOULDBLOCK);
427 EXPORT_SYMBOL(blk_mq_alloc_request);
429 struct request *blk_mq_alloc_request_hctx(struct request_queue *q,
430 unsigned int op, blk_mq_req_flags_t flags, unsigned int hctx_idx)
432 struct blk_mq_alloc_data data = {
437 u64 alloc_time_ns = 0;
442 /* alloc_time includes depth and tag waits */
443 if (blk_queue_rq_alloc_time(q))
444 alloc_time_ns = ktime_get_ns();
447 * If the tag allocator sleeps we could get an allocation for a
448 * different hardware context. No need to complicate the low level
449 * allocator for this for the rare use case of a command tied to
452 if (WARN_ON_ONCE(!(flags & (BLK_MQ_REQ_NOWAIT | BLK_MQ_REQ_RESERVED))))
453 return ERR_PTR(-EINVAL);
455 if (hctx_idx >= q->nr_hw_queues)
456 return ERR_PTR(-EIO);
458 ret = blk_queue_enter(q, flags);
463 * Check if the hardware context is actually mapped to anything.
464 * If not tell the caller that it should skip this queue.
467 data.hctx = q->queue_hw_ctx[hctx_idx];
468 if (!blk_mq_hw_queue_mapped(data.hctx))
470 cpu = cpumask_first_and(data.hctx->cpumask, cpu_online_mask);
471 data.ctx = __blk_mq_get_ctx(q, cpu);
474 blk_mq_tag_busy(data.hctx);
477 tag = blk_mq_get_tag(&data);
478 if (tag == BLK_MQ_NO_TAG)
480 return blk_mq_rq_ctx_init(&data, tag, alloc_time_ns);
486 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx);
488 static void __blk_mq_free_request(struct request *rq)
490 struct request_queue *q = rq->q;
491 struct blk_mq_ctx *ctx = rq->mq_ctx;
492 struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
493 const int sched_tag = rq->internal_tag;
495 blk_crypto_free_request(rq);
496 blk_pm_mark_last_busy(rq);
498 if (rq->tag != BLK_MQ_NO_TAG)
499 blk_mq_put_tag(hctx->tags, ctx, rq->tag);
500 if (sched_tag != BLK_MQ_NO_TAG)
501 blk_mq_put_tag(hctx->sched_tags, ctx, sched_tag);
502 blk_mq_sched_restart(hctx);
506 void blk_mq_free_request(struct request *rq)
508 struct request_queue *q = rq->q;
509 struct elevator_queue *e = q->elevator;
510 struct blk_mq_ctx *ctx = rq->mq_ctx;
511 struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
513 if (rq->rq_flags & RQF_ELVPRIV) {
514 if (e && e->type->ops.finish_request)
515 e->type->ops.finish_request(rq);
517 put_io_context(rq->elv.icq->ioc);
522 ctx->rq_completed[rq_is_sync(rq)]++;
523 if (rq->rq_flags & RQF_MQ_INFLIGHT)
524 __blk_mq_dec_active_requests(hctx);
526 if (unlikely(laptop_mode && !blk_rq_is_passthrough(rq)))
527 laptop_io_completion(q->backing_dev_info);
531 WRITE_ONCE(rq->state, MQ_RQ_IDLE);
532 if (refcount_dec_and_test(&rq->ref))
533 __blk_mq_free_request(rq);
535 EXPORT_SYMBOL_GPL(blk_mq_free_request);
537 inline void __blk_mq_end_request(struct request *rq, blk_status_t error)
541 if (blk_mq_need_time_stamp(rq))
542 now = ktime_get_ns();
544 if (rq->rq_flags & RQF_STATS) {
545 blk_mq_poll_stats_start(rq->q);
546 blk_stat_add(rq, now);
549 blk_mq_sched_completed_request(rq, now);
551 blk_account_io_done(rq, now);
554 rq_qos_done(rq->q, rq);
555 rq->end_io(rq, error);
557 blk_mq_free_request(rq);
560 EXPORT_SYMBOL(__blk_mq_end_request);
562 void blk_mq_end_request(struct request *rq, blk_status_t error)
564 if (blk_update_request(rq, error, blk_rq_bytes(rq)))
566 __blk_mq_end_request(rq, error);
568 EXPORT_SYMBOL(blk_mq_end_request);
571 * Softirq action handler - move entries to local list and loop over them
572 * while passing them to the queue registered handler.
574 static __latent_entropy void blk_done_softirq(struct softirq_action *h)
576 struct list_head *cpu_list, local_list;
579 cpu_list = this_cpu_ptr(&blk_cpu_done);
580 list_replace_init(cpu_list, &local_list);
583 while (!list_empty(&local_list)) {
586 rq = list_entry(local_list.next, struct request, ipi_list);
587 list_del_init(&rq->ipi_list);
588 rq->q->mq_ops->complete(rq);
592 static void blk_mq_trigger_softirq(struct request *rq)
594 struct list_head *list;
597 local_irq_save(flags);
598 list = this_cpu_ptr(&blk_cpu_done);
599 list_add_tail(&rq->ipi_list, list);
602 * If the list only contains our just added request, signal a raise of
603 * the softirq. If there are already entries there, someone already
604 * raised the irq but it hasn't run yet.
606 if (list->next == &rq->ipi_list)
607 raise_softirq_irqoff(BLOCK_SOFTIRQ);
608 local_irq_restore(flags);
611 static int blk_softirq_cpu_dead(unsigned int cpu)
614 * If a CPU goes away, splice its entries to the current CPU
615 * and trigger a run of the softirq
618 list_splice_init(&per_cpu(blk_cpu_done, cpu),
619 this_cpu_ptr(&blk_cpu_done));
620 raise_softirq_irqoff(BLOCK_SOFTIRQ);
627 static void __blk_mq_complete_request_remote(void *data)
629 struct request *rq = data;
632 * For most of single queue controllers, there is only one irq vector
633 * for handling I/O completion, and the only irq's affinity is set
634 * to all possible CPUs. On most of ARCHs, this affinity means the irq
635 * is handled on one specific CPU.
637 * So complete I/O requests in softirq context in case of single queue
638 * devices to avoid degrading I/O performance due to irqsoff latency.
640 if (rq->q->nr_hw_queues == 1)
641 blk_mq_trigger_softirq(rq);
643 rq->q->mq_ops->complete(rq);
646 static inline bool blk_mq_complete_need_ipi(struct request *rq)
648 int cpu = raw_smp_processor_id();
650 if (!IS_ENABLED(CONFIG_SMP) ||
651 !test_bit(QUEUE_FLAG_SAME_COMP, &rq->q->queue_flags))
654 /* same CPU or cache domain? Complete locally */
655 if (cpu == rq->mq_ctx->cpu ||
656 (!test_bit(QUEUE_FLAG_SAME_FORCE, &rq->q->queue_flags) &&
657 cpus_share_cache(cpu, rq->mq_ctx->cpu)))
660 /* don't try to IPI to an offline CPU */
661 return cpu_online(rq->mq_ctx->cpu);
664 bool blk_mq_complete_request_remote(struct request *rq)
666 WRITE_ONCE(rq->state, MQ_RQ_COMPLETE);
669 * For a polled request, always complete locallly, it's pointless
670 * to redirect the completion.
672 if (rq->cmd_flags & REQ_HIPRI)
675 if (blk_mq_complete_need_ipi(rq)) {
676 INIT_CSD(&rq->csd, __blk_mq_complete_request_remote, rq);
677 smp_call_function_single_async(rq->mq_ctx->cpu, &rq->csd);
679 if (rq->q->nr_hw_queues > 1)
681 blk_mq_trigger_softirq(rq);
686 EXPORT_SYMBOL_GPL(blk_mq_complete_request_remote);
689 * blk_mq_complete_request - end I/O on a request
690 * @rq: the request being processed
693 * Complete a request by scheduling the ->complete_rq operation.
695 void blk_mq_complete_request(struct request *rq)
697 if (!blk_mq_complete_request_remote(rq))
698 rq->q->mq_ops->complete(rq);
700 EXPORT_SYMBOL(blk_mq_complete_request);
702 static void hctx_unlock(struct blk_mq_hw_ctx *hctx, int srcu_idx)
703 __releases(hctx->srcu)
705 if (!(hctx->flags & BLK_MQ_F_BLOCKING))
708 srcu_read_unlock(hctx->srcu, srcu_idx);
711 static void hctx_lock(struct blk_mq_hw_ctx *hctx, int *srcu_idx)
712 __acquires(hctx->srcu)
714 if (!(hctx->flags & BLK_MQ_F_BLOCKING)) {
715 /* shut up gcc false positive */
719 *srcu_idx = srcu_read_lock(hctx->srcu);
723 * blk_mq_start_request - Start processing a request
724 * @rq: Pointer to request to be started
726 * Function used by device drivers to notify the block layer that a request
727 * is going to be processed now, so blk layer can do proper initializations
728 * such as starting the timeout timer.
730 void blk_mq_start_request(struct request *rq)
732 struct request_queue *q = rq->q;
734 trace_block_rq_issue(rq);
736 if (test_bit(QUEUE_FLAG_STATS, &q->queue_flags)) {
737 rq->io_start_time_ns = ktime_get_ns();
738 rq->stats_sectors = blk_rq_sectors(rq);
739 rq->rq_flags |= RQF_STATS;
743 WARN_ON_ONCE(blk_mq_rq_state(rq) != MQ_RQ_IDLE);
746 WRITE_ONCE(rq->state, MQ_RQ_IN_FLIGHT);
748 #ifdef CONFIG_BLK_DEV_INTEGRITY
749 if (blk_integrity_rq(rq) && req_op(rq) == REQ_OP_WRITE)
750 q->integrity.profile->prepare_fn(rq);
753 EXPORT_SYMBOL(blk_mq_start_request);
755 static void __blk_mq_requeue_request(struct request *rq)
757 struct request_queue *q = rq->q;
759 blk_mq_put_driver_tag(rq);
761 trace_block_rq_requeue(rq);
762 rq_qos_requeue(q, rq);
764 if (blk_mq_request_started(rq)) {
765 WRITE_ONCE(rq->state, MQ_RQ_IDLE);
766 rq->rq_flags &= ~RQF_TIMED_OUT;
770 void blk_mq_requeue_request(struct request *rq, bool kick_requeue_list)
772 __blk_mq_requeue_request(rq);
774 /* this request will be re-inserted to io scheduler queue */
775 blk_mq_sched_requeue_request(rq);
777 BUG_ON(!list_empty(&rq->queuelist));
778 blk_mq_add_to_requeue_list(rq, true, kick_requeue_list);
780 EXPORT_SYMBOL(blk_mq_requeue_request);
782 static void blk_mq_requeue_work(struct work_struct *work)
784 struct request_queue *q =
785 container_of(work, struct request_queue, requeue_work.work);
787 struct request *rq, *next;
789 spin_lock_irq(&q->requeue_lock);
790 list_splice_init(&q->requeue_list, &rq_list);
791 spin_unlock_irq(&q->requeue_lock);
793 list_for_each_entry_safe(rq, next, &rq_list, queuelist) {
794 if (!(rq->rq_flags & (RQF_SOFTBARRIER | RQF_DONTPREP)))
797 rq->rq_flags &= ~RQF_SOFTBARRIER;
798 list_del_init(&rq->queuelist);
800 * If RQF_DONTPREP, rq has contained some driver specific
801 * data, so insert it to hctx dispatch list to avoid any
804 if (rq->rq_flags & RQF_DONTPREP)
805 blk_mq_request_bypass_insert(rq, false, false);
807 blk_mq_sched_insert_request(rq, true, false, false);
810 while (!list_empty(&rq_list)) {
811 rq = list_entry(rq_list.next, struct request, queuelist);
812 list_del_init(&rq->queuelist);
813 blk_mq_sched_insert_request(rq, false, false, false);
816 blk_mq_run_hw_queues(q, false);
819 void blk_mq_add_to_requeue_list(struct request *rq, bool at_head,
820 bool kick_requeue_list)
822 struct request_queue *q = rq->q;
826 * We abuse this flag that is otherwise used by the I/O scheduler to
827 * request head insertion from the workqueue.
829 BUG_ON(rq->rq_flags & RQF_SOFTBARRIER);
831 spin_lock_irqsave(&q->requeue_lock, flags);
833 rq->rq_flags |= RQF_SOFTBARRIER;
834 list_add(&rq->queuelist, &q->requeue_list);
836 list_add_tail(&rq->queuelist, &q->requeue_list);
838 spin_unlock_irqrestore(&q->requeue_lock, flags);
840 if (kick_requeue_list)
841 blk_mq_kick_requeue_list(q);
844 void blk_mq_kick_requeue_list(struct request_queue *q)
846 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND, &q->requeue_work, 0);
848 EXPORT_SYMBOL(blk_mq_kick_requeue_list);
850 void blk_mq_delay_kick_requeue_list(struct request_queue *q,
853 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND, &q->requeue_work,
854 msecs_to_jiffies(msecs));
856 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list);
858 struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
860 if (tag < tags->nr_tags) {
861 prefetch(tags->rqs[tag]);
862 return tags->rqs[tag];
867 EXPORT_SYMBOL(blk_mq_tag_to_rq);
869 static bool blk_mq_rq_inflight(struct blk_mq_hw_ctx *hctx, struct request *rq,
870 void *priv, bool reserved)
873 * If we find a request that isn't idle and the queue matches,
874 * we know the queue is busy. Return false to stop the iteration.
876 if (blk_mq_request_started(rq) && rq->q == hctx->queue) {
886 bool blk_mq_queue_inflight(struct request_queue *q)
890 blk_mq_queue_tag_busy_iter(q, blk_mq_rq_inflight, &busy);
893 EXPORT_SYMBOL_GPL(blk_mq_queue_inflight);
895 static void blk_mq_rq_timed_out(struct request *req, bool reserved)
897 req->rq_flags |= RQF_TIMED_OUT;
898 if (req->q->mq_ops->timeout) {
899 enum blk_eh_timer_return ret;
901 ret = req->q->mq_ops->timeout(req, reserved);
902 if (ret == BLK_EH_DONE)
904 WARN_ON_ONCE(ret != BLK_EH_RESET_TIMER);
910 static bool blk_mq_req_expired(struct request *rq, unsigned long *next)
912 unsigned long deadline;
914 if (blk_mq_rq_state(rq) != MQ_RQ_IN_FLIGHT)
916 if (rq->rq_flags & RQF_TIMED_OUT)
919 deadline = READ_ONCE(rq->deadline);
920 if (time_after_eq(jiffies, deadline))
925 else if (time_after(*next, deadline))
930 static bool blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
931 struct request *rq, void *priv, bool reserved)
933 unsigned long *next = priv;
936 * Just do a quick check if it is expired before locking the request in
937 * so we're not unnecessarilly synchronizing across CPUs.
939 if (!blk_mq_req_expired(rq, next))
943 * We have reason to believe the request may be expired. Take a
944 * reference on the request to lock this request lifetime into its
945 * currently allocated context to prevent it from being reallocated in
946 * the event the completion by-passes this timeout handler.
948 * If the reference was already released, then the driver beat the
949 * timeout handler to posting a natural completion.
951 if (!refcount_inc_not_zero(&rq->ref))
955 * The request is now locked and cannot be reallocated underneath the
956 * timeout handler's processing. Re-verify this exact request is truly
957 * expired; if it is not expired, then the request was completed and
958 * reallocated as a new request.
960 if (blk_mq_req_expired(rq, next))
961 blk_mq_rq_timed_out(rq, reserved);
963 if (is_flush_rq(rq, hctx))
965 else if (refcount_dec_and_test(&rq->ref))
966 __blk_mq_free_request(rq);
971 static void blk_mq_timeout_work(struct work_struct *work)
973 struct request_queue *q =
974 container_of(work, struct request_queue, timeout_work);
975 unsigned long next = 0;
976 struct blk_mq_hw_ctx *hctx;
979 /* A deadlock might occur if a request is stuck requiring a
980 * timeout at the same time a queue freeze is waiting
981 * completion, since the timeout code would not be able to
982 * acquire the queue reference here.
984 * That's why we don't use blk_queue_enter here; instead, we use
985 * percpu_ref_tryget directly, because we need to be able to
986 * obtain a reference even in the short window between the queue
987 * starting to freeze, by dropping the first reference in
988 * blk_freeze_queue_start, and the moment the last request is
989 * consumed, marked by the instant q_usage_counter reaches
992 if (!percpu_ref_tryget(&q->q_usage_counter))
995 blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &next);
998 mod_timer(&q->timeout, next);
1001 * Request timeouts are handled as a forward rolling timer. If
1002 * we end up here it means that no requests are pending and
1003 * also that no request has been pending for a while. Mark
1004 * each hctx as idle.
1006 queue_for_each_hw_ctx(q, hctx, i) {
1007 /* the hctx may be unmapped, so check it here */
1008 if (blk_mq_hw_queue_mapped(hctx))
1009 blk_mq_tag_idle(hctx);
1015 struct flush_busy_ctx_data {
1016 struct blk_mq_hw_ctx *hctx;
1017 struct list_head *list;
1020 static bool flush_busy_ctx(struct sbitmap *sb, unsigned int bitnr, void *data)
1022 struct flush_busy_ctx_data *flush_data = data;
1023 struct blk_mq_hw_ctx *hctx = flush_data->hctx;
1024 struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
1025 enum hctx_type type = hctx->type;
1027 spin_lock(&ctx->lock);
1028 list_splice_tail_init(&ctx->rq_lists[type], flush_data->list);
1029 sbitmap_clear_bit(sb, bitnr);
1030 spin_unlock(&ctx->lock);
1035 * Process software queues that have been marked busy, splicing them
1036 * to the for-dispatch
1038 void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list)
1040 struct flush_busy_ctx_data data = {
1045 sbitmap_for_each_set(&hctx->ctx_map, flush_busy_ctx, &data);
1047 EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs);
1049 struct dispatch_rq_data {
1050 struct blk_mq_hw_ctx *hctx;
1054 static bool dispatch_rq_from_ctx(struct sbitmap *sb, unsigned int bitnr,
1057 struct dispatch_rq_data *dispatch_data = data;
1058 struct blk_mq_hw_ctx *hctx = dispatch_data->hctx;
1059 struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
1060 enum hctx_type type = hctx->type;
1062 spin_lock(&ctx->lock);
1063 if (!list_empty(&ctx->rq_lists[type])) {
1064 dispatch_data->rq = list_entry_rq(ctx->rq_lists[type].next);
1065 list_del_init(&dispatch_data->rq->queuelist);
1066 if (list_empty(&ctx->rq_lists[type]))
1067 sbitmap_clear_bit(sb, bitnr);
1069 spin_unlock(&ctx->lock);
1071 return !dispatch_data->rq;
1074 struct request *blk_mq_dequeue_from_ctx(struct blk_mq_hw_ctx *hctx,
1075 struct blk_mq_ctx *start)
1077 unsigned off = start ? start->index_hw[hctx->type] : 0;
1078 struct dispatch_rq_data data = {
1083 __sbitmap_for_each_set(&hctx->ctx_map, off,
1084 dispatch_rq_from_ctx, &data);
1089 static inline unsigned int queued_to_index(unsigned int queued)
1094 return min(BLK_MQ_MAX_DISPATCH_ORDER - 1, ilog2(queued) + 1);
1097 static bool __blk_mq_get_driver_tag(struct request *rq)
1099 struct sbitmap_queue *bt = rq->mq_hctx->tags->bitmap_tags;
1100 unsigned int tag_offset = rq->mq_hctx->tags->nr_reserved_tags;
1103 blk_mq_tag_busy(rq->mq_hctx);
1105 if (blk_mq_tag_is_reserved(rq->mq_hctx->sched_tags, rq->internal_tag)) {
1106 bt = rq->mq_hctx->tags->breserved_tags;
1109 if (!hctx_may_queue(rq->mq_hctx, bt))
1113 tag = __sbitmap_queue_get(bt);
1114 if (tag == BLK_MQ_NO_TAG)
1117 rq->tag = tag + tag_offset;
1121 static bool blk_mq_get_driver_tag(struct request *rq)
1123 struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
1125 if (rq->tag == BLK_MQ_NO_TAG && !__blk_mq_get_driver_tag(rq))
1128 if ((hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED) &&
1129 !(rq->rq_flags & RQF_MQ_INFLIGHT)) {
1130 rq->rq_flags |= RQF_MQ_INFLIGHT;
1131 __blk_mq_inc_active_requests(hctx);
1133 hctx->tags->rqs[rq->tag] = rq;
1137 static int blk_mq_dispatch_wake(wait_queue_entry_t *wait, unsigned mode,
1138 int flags, void *key)
1140 struct blk_mq_hw_ctx *hctx;
1142 hctx = container_of(wait, struct blk_mq_hw_ctx, dispatch_wait);
1144 spin_lock(&hctx->dispatch_wait_lock);
1145 if (!list_empty(&wait->entry)) {
1146 struct sbitmap_queue *sbq;
1148 list_del_init(&wait->entry);
1149 sbq = hctx->tags->bitmap_tags;
1150 atomic_dec(&sbq->ws_active);
1152 spin_unlock(&hctx->dispatch_wait_lock);
1154 blk_mq_run_hw_queue(hctx, true);
1159 * Mark us waiting for a tag. For shared tags, this involves hooking us into
1160 * the tag wakeups. For non-shared tags, we can simply mark us needing a
1161 * restart. For both cases, take care to check the condition again after
1162 * marking us as waiting.
1164 static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx *hctx,
1167 struct sbitmap_queue *sbq = hctx->tags->bitmap_tags;
1168 struct wait_queue_head *wq;
1169 wait_queue_entry_t *wait;
1172 if (!(hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED)) {
1173 blk_mq_sched_mark_restart_hctx(hctx);
1176 * It's possible that a tag was freed in the window between the
1177 * allocation failure and adding the hardware queue to the wait
1180 * Don't clear RESTART here, someone else could have set it.
1181 * At most this will cost an extra queue run.
1183 return blk_mq_get_driver_tag(rq);
1186 wait = &hctx->dispatch_wait;
1187 if (!list_empty_careful(&wait->entry))
1190 wq = &bt_wait_ptr(sbq, hctx)->wait;
1192 spin_lock_irq(&wq->lock);
1193 spin_lock(&hctx->dispatch_wait_lock);
1194 if (!list_empty(&wait->entry)) {
1195 spin_unlock(&hctx->dispatch_wait_lock);
1196 spin_unlock_irq(&wq->lock);
1200 atomic_inc(&sbq->ws_active);
1201 wait->flags &= ~WQ_FLAG_EXCLUSIVE;
1202 __add_wait_queue(wq, wait);
1205 * It's possible that a tag was freed in the window between the
1206 * allocation failure and adding the hardware queue to the wait
1209 ret = blk_mq_get_driver_tag(rq);
1211 spin_unlock(&hctx->dispatch_wait_lock);
1212 spin_unlock_irq(&wq->lock);
1217 * We got a tag, remove ourselves from the wait queue to ensure
1218 * someone else gets the wakeup.
1220 list_del_init(&wait->entry);
1221 atomic_dec(&sbq->ws_active);
1222 spin_unlock(&hctx->dispatch_wait_lock);
1223 spin_unlock_irq(&wq->lock);
1228 #define BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT 8
1229 #define BLK_MQ_DISPATCH_BUSY_EWMA_FACTOR 4
1231 * Update dispatch busy with the Exponential Weighted Moving Average(EWMA):
1232 * - EWMA is one simple way to compute running average value
1233 * - weight(7/8 and 1/8) is applied so that it can decrease exponentially
1234 * - take 4 as factor for avoiding to get too small(0) result, and this
1235 * factor doesn't matter because EWMA decreases exponentially
1237 static void blk_mq_update_dispatch_busy(struct blk_mq_hw_ctx *hctx, bool busy)
1241 if (hctx->queue->elevator)
1244 ewma = hctx->dispatch_busy;
1249 ewma *= BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT - 1;
1251 ewma += 1 << BLK_MQ_DISPATCH_BUSY_EWMA_FACTOR;
1252 ewma /= BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT;
1254 hctx->dispatch_busy = ewma;
1257 #define BLK_MQ_RESOURCE_DELAY 3 /* ms units */
1259 static void blk_mq_handle_dev_resource(struct request *rq,
1260 struct list_head *list)
1262 struct request *next =
1263 list_first_entry_or_null(list, struct request, queuelist);
1266 * If an I/O scheduler has been configured and we got a driver tag for
1267 * the next request already, free it.
1270 blk_mq_put_driver_tag(next);
1272 list_add(&rq->queuelist, list);
1273 __blk_mq_requeue_request(rq);
1276 static void blk_mq_handle_zone_resource(struct request *rq,
1277 struct list_head *zone_list)
1280 * If we end up here it is because we cannot dispatch a request to a
1281 * specific zone due to LLD level zone-write locking or other zone
1282 * related resource not being available. In this case, set the request
1283 * aside in zone_list for retrying it later.
1285 list_add(&rq->queuelist, zone_list);
1286 __blk_mq_requeue_request(rq);
1289 enum prep_dispatch {
1291 PREP_DISPATCH_NO_TAG,
1292 PREP_DISPATCH_NO_BUDGET,
1295 static enum prep_dispatch blk_mq_prep_dispatch_rq(struct request *rq,
1298 struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
1300 if (need_budget && !blk_mq_get_dispatch_budget(rq->q)) {
1301 blk_mq_put_driver_tag(rq);
1302 return PREP_DISPATCH_NO_BUDGET;
1305 if (!blk_mq_get_driver_tag(rq)) {
1307 * The initial allocation attempt failed, so we need to
1308 * rerun the hardware queue when a tag is freed. The
1309 * waitqueue takes care of that. If the queue is run
1310 * before we add this entry back on the dispatch list,
1311 * we'll re-run it below.
1313 if (!blk_mq_mark_tag_wait(hctx, rq)) {
1315 * All budgets not got from this function will be put
1316 * together during handling partial dispatch
1319 blk_mq_put_dispatch_budget(rq->q);
1320 return PREP_DISPATCH_NO_TAG;
1324 return PREP_DISPATCH_OK;
1327 /* release all allocated budgets before calling to blk_mq_dispatch_rq_list */
1328 static void blk_mq_release_budgets(struct request_queue *q,
1329 unsigned int nr_budgets)
1333 for (i = 0; i < nr_budgets; i++)
1334 blk_mq_put_dispatch_budget(q);
1338 * Returns true if we did some work AND can potentially do more.
1340 bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list,
1341 unsigned int nr_budgets)
1343 enum prep_dispatch prep;
1344 struct request_queue *q = hctx->queue;
1345 struct request *rq, *nxt;
1347 blk_status_t ret = BLK_STS_OK;
1348 LIST_HEAD(zone_list);
1350 if (list_empty(list))
1354 * Now process all the entries, sending them to the driver.
1356 errors = queued = 0;
1358 struct blk_mq_queue_data bd;
1360 rq = list_first_entry(list, struct request, queuelist);
1362 WARN_ON_ONCE(hctx != rq->mq_hctx);
1363 prep = blk_mq_prep_dispatch_rq(rq, !nr_budgets);
1364 if (prep != PREP_DISPATCH_OK)
1367 list_del_init(&rq->queuelist);
1372 * Flag last if we have no more requests, or if we have more
1373 * but can't assign a driver tag to it.
1375 if (list_empty(list))
1378 nxt = list_first_entry(list, struct request, queuelist);
1379 bd.last = !blk_mq_get_driver_tag(nxt);
1383 * once the request is queued to lld, no need to cover the
1388 ret = q->mq_ops->queue_rq(hctx, &bd);
1393 case BLK_STS_RESOURCE:
1394 case BLK_STS_DEV_RESOURCE:
1395 blk_mq_handle_dev_resource(rq, list);
1397 case BLK_STS_ZONE_RESOURCE:
1399 * Move the request to zone_list and keep going through
1400 * the dispatch list to find more requests the drive can
1403 blk_mq_handle_zone_resource(rq, &zone_list);
1407 blk_mq_end_request(rq, ret);
1409 } while (!list_empty(list));
1411 if (!list_empty(&zone_list))
1412 list_splice_tail_init(&zone_list, list);
1414 hctx->dispatched[queued_to_index(queued)]++;
1416 /* If we didn't flush the entire list, we could have told the driver
1417 * there was more coming, but that turned out to be a lie.
1419 if ((!list_empty(list) || errors) && q->mq_ops->commit_rqs && queued)
1420 q->mq_ops->commit_rqs(hctx);
1422 * Any items that need requeuing? Stuff them into hctx->dispatch,
1423 * that is where we will continue on next queue run.
1425 if (!list_empty(list)) {
1427 /* For non-shared tags, the RESTART check will suffice */
1428 bool no_tag = prep == PREP_DISPATCH_NO_TAG &&
1429 (hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED);
1430 bool no_budget_avail = prep == PREP_DISPATCH_NO_BUDGET;
1432 blk_mq_release_budgets(q, nr_budgets);
1434 spin_lock(&hctx->lock);
1435 list_splice_tail_init(list, &hctx->dispatch);
1436 spin_unlock(&hctx->lock);
1439 * Order adding requests to hctx->dispatch and checking
1440 * SCHED_RESTART flag. The pair of this smp_mb() is the one
1441 * in blk_mq_sched_restart(). Avoid restart code path to
1442 * miss the new added requests to hctx->dispatch, meantime
1443 * SCHED_RESTART is observed here.
1448 * If SCHED_RESTART was set by the caller of this function and
1449 * it is no longer set that means that it was cleared by another
1450 * thread and hence that a queue rerun is needed.
1452 * If 'no_tag' is set, that means that we failed getting
1453 * a driver tag with an I/O scheduler attached. If our dispatch
1454 * waitqueue is no longer active, ensure that we run the queue
1455 * AFTER adding our entries back to the list.
1457 * If no I/O scheduler has been configured it is possible that
1458 * the hardware queue got stopped and restarted before requests
1459 * were pushed back onto the dispatch list. Rerun the queue to
1460 * avoid starvation. Notes:
1461 * - blk_mq_run_hw_queue() checks whether or not a queue has
1462 * been stopped before rerunning a queue.
1463 * - Some but not all block drivers stop a queue before
1464 * returning BLK_STS_RESOURCE. Two exceptions are scsi-mq
1467 * If driver returns BLK_STS_RESOURCE and SCHED_RESTART
1468 * bit is set, run queue after a delay to avoid IO stalls
1469 * that could otherwise occur if the queue is idle. We'll do
1470 * similar if we couldn't get budget and SCHED_RESTART is set.
1472 needs_restart = blk_mq_sched_needs_restart(hctx);
1473 if (!needs_restart ||
1474 (no_tag && list_empty_careful(&hctx->dispatch_wait.entry)))
1475 blk_mq_run_hw_queue(hctx, true);
1476 else if (needs_restart && (ret == BLK_STS_RESOURCE ||
1478 blk_mq_delay_run_hw_queue(hctx, BLK_MQ_RESOURCE_DELAY);
1480 blk_mq_update_dispatch_busy(hctx, true);
1483 blk_mq_update_dispatch_busy(hctx, false);
1485 return (queued + errors) != 0;
1489 * __blk_mq_run_hw_queue - Run a hardware queue.
1490 * @hctx: Pointer to the hardware queue to run.
1492 * Send pending requests to the hardware.
1494 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
1499 * We should be running this queue from one of the CPUs that
1502 * There are at least two related races now between setting
1503 * hctx->next_cpu from blk_mq_hctx_next_cpu() and running
1504 * __blk_mq_run_hw_queue():
1506 * - hctx->next_cpu is found offline in blk_mq_hctx_next_cpu(),
1507 * but later it becomes online, then this warning is harmless
1510 * - hctx->next_cpu is found online in blk_mq_hctx_next_cpu(),
1511 * but later it becomes offline, then the warning can't be
1512 * triggered, and we depend on blk-mq timeout handler to
1513 * handle dispatched requests to this hctx
1515 if (!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask) &&
1516 cpu_online(hctx->next_cpu)) {
1517 printk(KERN_WARNING "run queue from wrong CPU %d, hctx %s\n",
1518 raw_smp_processor_id(),
1519 cpumask_empty(hctx->cpumask) ? "inactive": "active");
1524 * We can't run the queue inline with ints disabled. Ensure that
1525 * we catch bad users of this early.
1527 WARN_ON_ONCE(in_interrupt());
1529 might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
1531 hctx_lock(hctx, &srcu_idx);
1532 blk_mq_sched_dispatch_requests(hctx);
1533 hctx_unlock(hctx, srcu_idx);
1536 static inline int blk_mq_first_mapped_cpu(struct blk_mq_hw_ctx *hctx)
1538 int cpu = cpumask_first_and(hctx->cpumask, cpu_online_mask);
1540 if (cpu >= nr_cpu_ids)
1541 cpu = cpumask_first(hctx->cpumask);
1546 * It'd be great if the workqueue API had a way to pass
1547 * in a mask and had some smarts for more clever placement.
1548 * For now we just round-robin here, switching for every
1549 * BLK_MQ_CPU_WORK_BATCH queued items.
1551 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
1554 int next_cpu = hctx->next_cpu;
1556 if (hctx->queue->nr_hw_queues == 1)
1557 return WORK_CPU_UNBOUND;
1559 if (--hctx->next_cpu_batch <= 0) {
1561 next_cpu = cpumask_next_and(next_cpu, hctx->cpumask,
1563 if (next_cpu >= nr_cpu_ids)
1564 next_cpu = blk_mq_first_mapped_cpu(hctx);
1565 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
1569 * Do unbound schedule if we can't find a online CPU for this hctx,
1570 * and it should only happen in the path of handling CPU DEAD.
1572 if (!cpu_online(next_cpu)) {
1579 * Make sure to re-select CPU next time once after CPUs
1580 * in hctx->cpumask become online again.
1582 hctx->next_cpu = next_cpu;
1583 hctx->next_cpu_batch = 1;
1584 return WORK_CPU_UNBOUND;
1587 hctx->next_cpu = next_cpu;
1592 * __blk_mq_delay_run_hw_queue - Run (or schedule to run) a hardware queue.
1593 * @hctx: Pointer to the hardware queue to run.
1594 * @async: If we want to run the queue asynchronously.
1595 * @msecs: Milliseconds of delay to wait before running the queue.
1597 * If !@async, try to run the queue now. Else, run the queue asynchronously and
1598 * with a delay of @msecs.
1600 static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async,
1601 unsigned long msecs)
1603 if (unlikely(blk_mq_hctx_stopped(hctx)))
1606 if (!async && !(hctx->flags & BLK_MQ_F_BLOCKING)) {
1607 int cpu = get_cpu();
1608 if (cpumask_test_cpu(cpu, hctx->cpumask)) {
1609 __blk_mq_run_hw_queue(hctx);
1617 kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx), &hctx->run_work,
1618 msecs_to_jiffies(msecs));
1622 * blk_mq_delay_run_hw_queue - Run a hardware queue asynchronously.
1623 * @hctx: Pointer to the hardware queue to run.
1624 * @msecs: Milliseconds of delay to wait before running the queue.
1626 * Run a hardware queue asynchronously with a delay of @msecs.
1628 void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
1630 __blk_mq_delay_run_hw_queue(hctx, true, msecs);
1632 EXPORT_SYMBOL(blk_mq_delay_run_hw_queue);
1635 * blk_mq_run_hw_queue - Start to run a hardware queue.
1636 * @hctx: Pointer to the hardware queue to run.
1637 * @async: If we want to run the queue asynchronously.
1639 * Check if the request queue is not in a quiesced state and if there are
1640 * pending requests to be sent. If this is true, run the queue to send requests
1643 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
1649 * When queue is quiesced, we may be switching io scheduler, or
1650 * updating nr_hw_queues, or other things, and we can't run queue
1651 * any more, even __blk_mq_hctx_has_pending() can't be called safely.
1653 * And queue will be rerun in blk_mq_unquiesce_queue() if it is
1656 hctx_lock(hctx, &srcu_idx);
1657 need_run = !blk_queue_quiesced(hctx->queue) &&
1658 blk_mq_hctx_has_pending(hctx);
1659 hctx_unlock(hctx, srcu_idx);
1662 __blk_mq_delay_run_hw_queue(hctx, async, 0);
1664 EXPORT_SYMBOL(blk_mq_run_hw_queue);
1667 * blk_mq_run_hw_queues - Run all hardware queues in a request queue.
1668 * @q: Pointer to the request queue to run.
1669 * @async: If we want to run the queue asynchronously.
1671 void blk_mq_run_hw_queues(struct request_queue *q, bool async)
1673 struct blk_mq_hw_ctx *hctx;
1676 queue_for_each_hw_ctx(q, hctx, i) {
1677 if (blk_mq_hctx_stopped(hctx))
1680 blk_mq_run_hw_queue(hctx, async);
1683 EXPORT_SYMBOL(blk_mq_run_hw_queues);
1686 * blk_mq_delay_run_hw_queues - Run all hardware queues asynchronously.
1687 * @q: Pointer to the request queue to run.
1688 * @msecs: Milliseconds of delay to wait before running the queues.
1690 void blk_mq_delay_run_hw_queues(struct request_queue *q, unsigned long msecs)
1692 struct blk_mq_hw_ctx *hctx;
1695 queue_for_each_hw_ctx(q, hctx, i) {
1696 if (blk_mq_hctx_stopped(hctx))
1699 blk_mq_delay_run_hw_queue(hctx, msecs);
1702 EXPORT_SYMBOL(blk_mq_delay_run_hw_queues);
1705 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1706 * @q: request queue.
1708 * The caller is responsible for serializing this function against
1709 * blk_mq_{start,stop}_hw_queue().
1711 bool blk_mq_queue_stopped(struct request_queue *q)
1713 struct blk_mq_hw_ctx *hctx;
1716 queue_for_each_hw_ctx(q, hctx, i)
1717 if (blk_mq_hctx_stopped(hctx))
1722 EXPORT_SYMBOL(blk_mq_queue_stopped);
1725 * This function is often used for pausing .queue_rq() by driver when
1726 * there isn't enough resource or some conditions aren't satisfied, and
1727 * BLK_STS_RESOURCE is usually returned.
1729 * We do not guarantee that dispatch can be drained or blocked
1730 * after blk_mq_stop_hw_queue() returns. Please use
1731 * blk_mq_quiesce_queue() for that requirement.
1733 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
1735 cancel_delayed_work(&hctx->run_work);
1737 set_bit(BLK_MQ_S_STOPPED, &hctx->state);
1739 EXPORT_SYMBOL(blk_mq_stop_hw_queue);
1742 * This function is often used for pausing .queue_rq() by driver when
1743 * there isn't enough resource or some conditions aren't satisfied, and
1744 * BLK_STS_RESOURCE is usually returned.
1746 * We do not guarantee that dispatch can be drained or blocked
1747 * after blk_mq_stop_hw_queues() returns. Please use
1748 * blk_mq_quiesce_queue() for that requirement.
1750 void blk_mq_stop_hw_queues(struct request_queue *q)
1752 struct blk_mq_hw_ctx *hctx;
1755 queue_for_each_hw_ctx(q, hctx, i)
1756 blk_mq_stop_hw_queue(hctx);
1758 EXPORT_SYMBOL(blk_mq_stop_hw_queues);
1760 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
1762 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1764 blk_mq_run_hw_queue(hctx, false);
1766 EXPORT_SYMBOL(blk_mq_start_hw_queue);
1768 void blk_mq_start_hw_queues(struct request_queue *q)
1770 struct blk_mq_hw_ctx *hctx;
1773 queue_for_each_hw_ctx(q, hctx, i)
1774 blk_mq_start_hw_queue(hctx);
1776 EXPORT_SYMBOL(blk_mq_start_hw_queues);
1778 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
1780 if (!blk_mq_hctx_stopped(hctx))
1783 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1784 blk_mq_run_hw_queue(hctx, async);
1786 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue);
1788 void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async)
1790 struct blk_mq_hw_ctx *hctx;
1793 queue_for_each_hw_ctx(q, hctx, i)
1794 blk_mq_start_stopped_hw_queue(hctx, async);
1796 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);
1798 static void blk_mq_run_work_fn(struct work_struct *work)
1800 struct blk_mq_hw_ctx *hctx;
1802 hctx = container_of(work, struct blk_mq_hw_ctx, run_work.work);
1805 * If we are stopped, don't run the queue.
1807 if (blk_mq_hctx_stopped(hctx))
1810 __blk_mq_run_hw_queue(hctx);
1813 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx,
1817 struct blk_mq_ctx *ctx = rq->mq_ctx;
1818 enum hctx_type type = hctx->type;
1820 lockdep_assert_held(&ctx->lock);
1822 trace_block_rq_insert(rq);
1825 list_add(&rq->queuelist, &ctx->rq_lists[type]);
1827 list_add_tail(&rq->queuelist, &ctx->rq_lists[type]);
1830 void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
1833 struct blk_mq_ctx *ctx = rq->mq_ctx;
1835 lockdep_assert_held(&ctx->lock);
1837 __blk_mq_insert_req_list(hctx, rq, at_head);
1838 blk_mq_hctx_mark_pending(hctx, ctx);
1842 * blk_mq_request_bypass_insert - Insert a request at dispatch list.
1843 * @rq: Pointer to request to be inserted.
1844 * @at_head: true if the request should be inserted at the head of the list.
1845 * @run_queue: If we should run the hardware queue after inserting the request.
1847 * Should only be used carefully, when the caller knows we want to
1848 * bypass a potential IO scheduler on the target device.
1850 void blk_mq_request_bypass_insert(struct request *rq, bool at_head,
1853 struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
1855 spin_lock(&hctx->lock);
1857 list_add(&rq->queuelist, &hctx->dispatch);
1859 list_add_tail(&rq->queuelist, &hctx->dispatch);
1860 spin_unlock(&hctx->lock);
1863 blk_mq_run_hw_queue(hctx, false);
1866 void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
1867 struct list_head *list)
1871 enum hctx_type type = hctx->type;
1874 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1877 list_for_each_entry(rq, list, queuelist) {
1878 BUG_ON(rq->mq_ctx != ctx);
1879 trace_block_rq_insert(rq);
1882 spin_lock(&ctx->lock);
1883 list_splice_tail_init(list, &ctx->rq_lists[type]);
1884 blk_mq_hctx_mark_pending(hctx, ctx);
1885 spin_unlock(&ctx->lock);
1888 static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b)
1890 struct request *rqa = container_of(a, struct request, queuelist);
1891 struct request *rqb = container_of(b, struct request, queuelist);
1893 if (rqa->mq_ctx != rqb->mq_ctx)
1894 return rqa->mq_ctx > rqb->mq_ctx;
1895 if (rqa->mq_hctx != rqb->mq_hctx)
1896 return rqa->mq_hctx > rqb->mq_hctx;
1898 return blk_rq_pos(rqa) > blk_rq_pos(rqb);
1901 void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
1905 if (list_empty(&plug->mq_list))
1907 list_splice_init(&plug->mq_list, &list);
1909 if (plug->rq_count > 2 && plug->multiple_queues)
1910 list_sort(NULL, &list, plug_rq_cmp);
1915 struct list_head rq_list;
1916 struct request *rq, *head_rq = list_entry_rq(list.next);
1917 struct list_head *pos = &head_rq->queuelist; /* skip first */
1918 struct blk_mq_hw_ctx *this_hctx = head_rq->mq_hctx;
1919 struct blk_mq_ctx *this_ctx = head_rq->mq_ctx;
1920 unsigned int depth = 1;
1922 list_for_each_continue(pos, &list) {
1923 rq = list_entry_rq(pos);
1925 if (rq->mq_hctx != this_hctx || rq->mq_ctx != this_ctx)
1930 list_cut_before(&rq_list, &list, pos);
1931 trace_block_unplug(head_rq->q, depth, !from_schedule);
1932 blk_mq_sched_insert_requests(this_hctx, this_ctx, &rq_list,
1934 } while(!list_empty(&list));
1937 static void blk_mq_bio_to_request(struct request *rq, struct bio *bio,
1938 unsigned int nr_segs)
1942 if (bio->bi_opf & REQ_RAHEAD)
1943 rq->cmd_flags |= REQ_FAILFAST_MASK;
1945 rq->__sector = bio->bi_iter.bi_sector;
1946 rq->write_hint = bio->bi_write_hint;
1947 blk_rq_bio_prep(rq, bio, nr_segs);
1949 /* This can't fail, since GFP_NOIO includes __GFP_DIRECT_RECLAIM. */
1950 err = blk_crypto_rq_bio_prep(rq, bio, GFP_NOIO);
1953 blk_account_io_start(rq);
1956 static blk_status_t __blk_mq_issue_directly(struct blk_mq_hw_ctx *hctx,
1958 blk_qc_t *cookie, bool last)
1960 struct request_queue *q = rq->q;
1961 struct blk_mq_queue_data bd = {
1965 blk_qc_t new_cookie;
1968 new_cookie = request_to_qc_t(hctx, rq);
1971 * For OK queue, we are done. For error, caller may kill it.
1972 * Any other error (busy), just add it to our list as we
1973 * previously would have done.
1975 ret = q->mq_ops->queue_rq(hctx, &bd);
1978 blk_mq_update_dispatch_busy(hctx, false);
1979 *cookie = new_cookie;
1981 case BLK_STS_RESOURCE:
1982 case BLK_STS_DEV_RESOURCE:
1983 blk_mq_update_dispatch_busy(hctx, true);
1984 __blk_mq_requeue_request(rq);
1987 blk_mq_update_dispatch_busy(hctx, false);
1988 *cookie = BLK_QC_T_NONE;
1995 static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
1998 bool bypass_insert, bool last)
2000 struct request_queue *q = rq->q;
2001 bool run_queue = true;
2004 * RCU or SRCU read lock is needed before checking quiesced flag.
2006 * When queue is stopped or quiesced, ignore 'bypass_insert' from
2007 * blk_mq_request_issue_directly(), and return BLK_STS_OK to caller,
2008 * and avoid driver to try to dispatch again.
2010 if (blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q)) {
2012 bypass_insert = false;
2016 if (q->elevator && !bypass_insert)
2019 if (!blk_mq_get_dispatch_budget(q))
2022 if (!blk_mq_get_driver_tag(rq)) {
2023 blk_mq_put_dispatch_budget(q);
2027 return __blk_mq_issue_directly(hctx, rq, cookie, last);
2030 return BLK_STS_RESOURCE;
2032 blk_mq_sched_insert_request(rq, false, run_queue, false);
2038 * blk_mq_try_issue_directly - Try to send a request directly to device driver.
2039 * @hctx: Pointer of the associated hardware queue.
2040 * @rq: Pointer to request to be sent.
2041 * @cookie: Request queue cookie.
2043 * If the device has enough resources to accept a new request now, send the
2044 * request directly to device driver. Else, insert at hctx->dispatch queue, so
2045 * we can try send it another time in the future. Requests inserted at this
2046 * queue have higher priority.
2048 static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
2049 struct request *rq, blk_qc_t *cookie)
2054 might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
2056 hctx_lock(hctx, &srcu_idx);
2058 ret = __blk_mq_try_issue_directly(hctx, rq, cookie, false, true);
2059 if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE)
2060 blk_mq_request_bypass_insert(rq, false, true);
2061 else if (ret != BLK_STS_OK)
2062 blk_mq_end_request(rq, ret);
2064 hctx_unlock(hctx, srcu_idx);
2067 blk_status_t blk_mq_request_issue_directly(struct request *rq, bool last)
2071 blk_qc_t unused_cookie;
2072 struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
2074 hctx_lock(hctx, &srcu_idx);
2075 ret = __blk_mq_try_issue_directly(hctx, rq, &unused_cookie, true, last);
2076 hctx_unlock(hctx, srcu_idx);
2081 void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx,
2082 struct list_head *list)
2087 while (!list_empty(list)) {
2089 struct request *rq = list_first_entry(list, struct request,
2092 list_del_init(&rq->queuelist);
2093 ret = blk_mq_request_issue_directly(rq, list_empty(list));
2094 if (ret != BLK_STS_OK) {
2095 if (ret == BLK_STS_RESOURCE ||
2096 ret == BLK_STS_DEV_RESOURCE) {
2097 blk_mq_request_bypass_insert(rq, false,
2101 blk_mq_end_request(rq, ret);
2108 * If we didn't flush the entire list, we could have told
2109 * the driver there was more coming, but that turned out to
2112 if ((!list_empty(list) || errors) &&
2113 hctx->queue->mq_ops->commit_rqs && queued)
2114 hctx->queue->mq_ops->commit_rqs(hctx);
2117 static void blk_add_rq_to_plug(struct blk_plug *plug, struct request *rq)
2119 list_add_tail(&rq->queuelist, &plug->mq_list);
2121 if (!plug->multiple_queues && !list_is_singular(&plug->mq_list)) {
2122 struct request *tmp;
2124 tmp = list_first_entry(&plug->mq_list, struct request,
2126 if (tmp->q != rq->q)
2127 plug->multiple_queues = true;
2132 * blk_mq_submit_bio - Create and send a request to block device.
2133 * @bio: Bio pointer.
2135 * Builds up a request structure from @q and @bio and send to the device. The
2136 * request may not be queued directly to hardware if:
2137 * * This request can be merged with another one
2138 * * We want to place request at plug queue for possible future merging
2139 * * There is an IO scheduler active at this queue
2141 * It will not queue the request if there is an error with the bio, or at the
2144 * Returns: Request queue cookie.
2146 blk_qc_t blk_mq_submit_bio(struct bio *bio)
2148 struct request_queue *q = bio->bi_disk->queue;
2149 const int is_sync = op_is_sync(bio->bi_opf);
2150 const int is_flush_fua = op_is_flush(bio->bi_opf);
2151 struct blk_mq_alloc_data data = {
2155 struct blk_plug *plug;
2156 struct request *same_queue_rq = NULL;
2157 unsigned int nr_segs;
2162 blk_queue_bounce(q, &bio);
2163 __blk_queue_split(&bio, &nr_segs);
2165 if (!bio_integrity_prep(bio))
2168 if (!is_flush_fua && !blk_queue_nomerges(q) &&
2169 blk_attempt_plug_merge(q, bio, nr_segs, &same_queue_rq))
2172 if (blk_mq_sched_bio_merge(q, bio, nr_segs))
2175 rq_qos_throttle(q, bio);
2177 hipri = bio->bi_opf & REQ_HIPRI;
2179 data.cmd_flags = bio->bi_opf;
2180 rq = __blk_mq_alloc_request(&data);
2181 if (unlikely(!rq)) {
2182 rq_qos_cleanup(q, bio);
2183 if (bio->bi_opf & REQ_NOWAIT)
2184 bio_wouldblock_error(bio);
2188 trace_block_getrq(bio);
2190 rq_qos_track(q, rq, bio);
2192 cookie = request_to_qc_t(data.hctx, rq);
2194 blk_mq_bio_to_request(rq, bio, nr_segs);
2196 ret = blk_crypto_init_request(rq);
2197 if (ret != BLK_STS_OK) {
2198 bio->bi_status = ret;
2200 blk_mq_free_request(rq);
2201 return BLK_QC_T_NONE;
2204 plug = blk_mq_plug(q, bio);
2205 if (unlikely(is_flush_fua)) {
2206 /* Bypass scheduler for flush requests */
2207 blk_insert_flush(rq);
2208 blk_mq_run_hw_queue(data.hctx, true);
2209 } else if (plug && (q->nr_hw_queues == 1 || q->mq_ops->commit_rqs ||
2210 !blk_queue_nonrot(q))) {
2212 * Use plugging if we have a ->commit_rqs() hook as well, as
2213 * we know the driver uses bd->last in a smart fashion.
2215 * Use normal plugging if this disk is slow HDD, as sequential
2216 * IO may benefit a lot from plug merging.
2218 unsigned int request_count = plug->rq_count;
2219 struct request *last = NULL;
2222 trace_block_plug(q);
2224 last = list_entry_rq(plug->mq_list.prev);
2226 if (request_count >= BLK_MAX_REQUEST_COUNT || (last &&
2227 blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
2228 blk_flush_plug_list(plug, false);
2229 trace_block_plug(q);
2232 blk_add_rq_to_plug(plug, rq);
2233 } else if (q->elevator) {
2234 /* Insert the request at the IO scheduler queue */
2235 blk_mq_sched_insert_request(rq, false, true, true);
2236 } else if (plug && !blk_queue_nomerges(q)) {
2238 * We do limited plugging. If the bio can be merged, do that.
2239 * Otherwise the existing request in the plug list will be
2240 * issued. So the plug list will have one request at most
2241 * The plug list might get flushed before this. If that happens,
2242 * the plug list is empty, and same_queue_rq is invalid.
2244 if (list_empty(&plug->mq_list))
2245 same_queue_rq = NULL;
2246 if (same_queue_rq) {
2247 list_del_init(&same_queue_rq->queuelist);
2250 blk_add_rq_to_plug(plug, rq);
2251 trace_block_plug(q);
2253 if (same_queue_rq) {
2254 data.hctx = same_queue_rq->mq_hctx;
2255 trace_block_unplug(q, 1, true);
2256 blk_mq_try_issue_directly(data.hctx, same_queue_rq,
2259 } else if ((q->nr_hw_queues > 1 && is_sync) ||
2260 !data.hctx->dispatch_busy) {
2262 * There is no scheduler and we can try to send directly
2265 blk_mq_try_issue_directly(data.hctx, rq, &cookie);
2268 blk_mq_sched_insert_request(rq, false, true, true);
2272 return BLK_QC_T_NONE;
2276 return BLK_QC_T_NONE;
2279 void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
2280 unsigned int hctx_idx)
2284 if (tags->rqs && set->ops->exit_request) {
2287 for (i = 0; i < tags->nr_tags; i++) {
2288 struct request *rq = tags->static_rqs[i];
2292 set->ops->exit_request(set, rq, hctx_idx);
2293 tags->static_rqs[i] = NULL;
2297 while (!list_empty(&tags->page_list)) {
2298 page = list_first_entry(&tags->page_list, struct page, lru);
2299 list_del_init(&page->lru);
2301 * Remove kmemleak object previously allocated in
2302 * blk_mq_alloc_rqs().
2304 kmemleak_free(page_address(page));
2305 __free_pages(page, page->private);
2309 void blk_mq_free_rq_map(struct blk_mq_tags *tags, unsigned int flags)
2313 kfree(tags->static_rqs);
2314 tags->static_rqs = NULL;
2316 blk_mq_free_tags(tags, flags);
2319 struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set,
2320 unsigned int hctx_idx,
2321 unsigned int nr_tags,
2322 unsigned int reserved_tags,
2325 struct blk_mq_tags *tags;
2328 node = blk_mq_hw_queue_to_node(&set->map[HCTX_TYPE_DEFAULT], hctx_idx);
2329 if (node == NUMA_NO_NODE)
2330 node = set->numa_node;
2332 tags = blk_mq_init_tags(nr_tags, reserved_tags, node, flags);
2336 tags->rqs = kcalloc_node(nr_tags, sizeof(struct request *),
2337 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
2340 blk_mq_free_tags(tags, flags);
2344 tags->static_rqs = kcalloc_node(nr_tags, sizeof(struct request *),
2345 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
2347 if (!tags->static_rqs) {
2349 blk_mq_free_tags(tags, flags);
2356 static size_t order_to_size(unsigned int order)
2358 return (size_t)PAGE_SIZE << order;
2361 static int blk_mq_init_request(struct blk_mq_tag_set *set, struct request *rq,
2362 unsigned int hctx_idx, int node)
2366 if (set->ops->init_request) {
2367 ret = set->ops->init_request(set, rq, hctx_idx, node);
2372 WRITE_ONCE(rq->state, MQ_RQ_IDLE);
2376 int blk_mq_alloc_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
2377 unsigned int hctx_idx, unsigned int depth)
2379 unsigned int i, j, entries_per_page, max_order = 4;
2380 size_t rq_size, left;
2383 node = blk_mq_hw_queue_to_node(&set->map[HCTX_TYPE_DEFAULT], hctx_idx);
2384 if (node == NUMA_NO_NODE)
2385 node = set->numa_node;
2387 INIT_LIST_HEAD(&tags->page_list);
2390 * rq_size is the size of the request plus driver payload, rounded
2391 * to the cacheline size
2393 rq_size = round_up(sizeof(struct request) + set->cmd_size,
2395 left = rq_size * depth;
2397 for (i = 0; i < depth; ) {
2398 int this_order = max_order;
2403 while (this_order && left < order_to_size(this_order - 1))
2407 page = alloc_pages_node(node,
2408 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY | __GFP_ZERO,
2414 if (order_to_size(this_order) < rq_size)
2421 page->private = this_order;
2422 list_add_tail(&page->lru, &tags->page_list);
2424 p = page_address(page);
2426 * Allow kmemleak to scan these pages as they contain pointers
2427 * to additional allocations like via ops->init_request().
2429 kmemleak_alloc(p, order_to_size(this_order), 1, GFP_NOIO);
2430 entries_per_page = order_to_size(this_order) / rq_size;
2431 to_do = min(entries_per_page, depth - i);
2432 left -= to_do * rq_size;
2433 for (j = 0; j < to_do; j++) {
2434 struct request *rq = p;
2436 tags->static_rqs[i] = rq;
2437 if (blk_mq_init_request(set, rq, hctx_idx, node)) {
2438 tags->static_rqs[i] = NULL;
2449 blk_mq_free_rqs(set, tags, hctx_idx);
2453 struct rq_iter_data {
2454 struct blk_mq_hw_ctx *hctx;
2458 static bool blk_mq_has_request(struct request *rq, void *data, bool reserved)
2460 struct rq_iter_data *iter_data = data;
2462 if (rq->mq_hctx != iter_data->hctx)
2464 iter_data->has_rq = true;
2468 static bool blk_mq_hctx_has_requests(struct blk_mq_hw_ctx *hctx)
2470 struct blk_mq_tags *tags = hctx->sched_tags ?
2471 hctx->sched_tags : hctx->tags;
2472 struct rq_iter_data data = {
2476 blk_mq_all_tag_iter(tags, blk_mq_has_request, &data);
2480 static inline bool blk_mq_last_cpu_in_hctx(unsigned int cpu,
2481 struct blk_mq_hw_ctx *hctx)
2483 if (cpumask_next_and(-1, hctx->cpumask, cpu_online_mask) != cpu)
2485 if (cpumask_next_and(cpu, hctx->cpumask, cpu_online_mask) < nr_cpu_ids)
2490 static int blk_mq_hctx_notify_offline(unsigned int cpu, struct hlist_node *node)
2492 struct blk_mq_hw_ctx *hctx = hlist_entry_safe(node,
2493 struct blk_mq_hw_ctx, cpuhp_online);
2495 if (!cpumask_test_cpu(cpu, hctx->cpumask) ||
2496 !blk_mq_last_cpu_in_hctx(cpu, hctx))
2500 * Prevent new request from being allocated on the current hctx.
2502 * The smp_mb__after_atomic() Pairs with the implied barrier in
2503 * test_and_set_bit_lock in sbitmap_get(). Ensures the inactive flag is
2504 * seen once we return from the tag allocator.
2506 set_bit(BLK_MQ_S_INACTIVE, &hctx->state);
2507 smp_mb__after_atomic();
2510 * Try to grab a reference to the queue and wait for any outstanding
2511 * requests. If we could not grab a reference the queue has been
2512 * frozen and there are no requests.
2514 if (percpu_ref_tryget(&hctx->queue->q_usage_counter)) {
2515 while (blk_mq_hctx_has_requests(hctx))
2517 percpu_ref_put(&hctx->queue->q_usage_counter);
2523 static int blk_mq_hctx_notify_online(unsigned int cpu, struct hlist_node *node)
2525 struct blk_mq_hw_ctx *hctx = hlist_entry_safe(node,
2526 struct blk_mq_hw_ctx, cpuhp_online);
2528 if (cpumask_test_cpu(cpu, hctx->cpumask))
2529 clear_bit(BLK_MQ_S_INACTIVE, &hctx->state);
2534 * 'cpu' is going away. splice any existing rq_list entries from this
2535 * software queue to the hw queue dispatch list, and ensure that it
2538 static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node)
2540 struct blk_mq_hw_ctx *hctx;
2541 struct blk_mq_ctx *ctx;
2543 enum hctx_type type;
2545 hctx = hlist_entry_safe(node, struct blk_mq_hw_ctx, cpuhp_dead);
2546 if (!cpumask_test_cpu(cpu, hctx->cpumask))
2549 ctx = __blk_mq_get_ctx(hctx->queue, cpu);
2552 spin_lock(&ctx->lock);
2553 if (!list_empty(&ctx->rq_lists[type])) {
2554 list_splice_init(&ctx->rq_lists[type], &tmp);
2555 blk_mq_hctx_clear_pending(hctx, ctx);
2557 spin_unlock(&ctx->lock);
2559 if (list_empty(&tmp))
2562 spin_lock(&hctx->lock);
2563 list_splice_tail_init(&tmp, &hctx->dispatch);
2564 spin_unlock(&hctx->lock);
2566 blk_mq_run_hw_queue(hctx, true);
2570 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx *hctx)
2572 if (!(hctx->flags & BLK_MQ_F_STACKING))
2573 cpuhp_state_remove_instance_nocalls(CPUHP_AP_BLK_MQ_ONLINE,
2574 &hctx->cpuhp_online);
2575 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD,
2579 /* hctx->ctxs will be freed in queue's release handler */
2580 static void blk_mq_exit_hctx(struct request_queue *q,
2581 struct blk_mq_tag_set *set,
2582 struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
2584 if (blk_mq_hw_queue_mapped(hctx))
2585 blk_mq_tag_idle(hctx);
2587 if (set->ops->exit_request)
2588 set->ops->exit_request(set, hctx->fq->flush_rq, hctx_idx);
2590 if (set->ops->exit_hctx)
2591 set->ops->exit_hctx(hctx, hctx_idx);
2593 blk_mq_remove_cpuhp(hctx);
2595 spin_lock(&q->unused_hctx_lock);
2596 list_add(&hctx->hctx_list, &q->unused_hctx_list);
2597 spin_unlock(&q->unused_hctx_lock);
2600 static void blk_mq_exit_hw_queues(struct request_queue *q,
2601 struct blk_mq_tag_set *set, int nr_queue)
2603 struct blk_mq_hw_ctx *hctx;
2606 queue_for_each_hw_ctx(q, hctx, i) {
2609 blk_mq_debugfs_unregister_hctx(hctx);
2610 blk_mq_exit_hctx(q, set, hctx, i);
2614 static int blk_mq_hw_ctx_size(struct blk_mq_tag_set *tag_set)
2616 int hw_ctx_size = sizeof(struct blk_mq_hw_ctx);
2618 BUILD_BUG_ON(ALIGN(offsetof(struct blk_mq_hw_ctx, srcu),
2619 __alignof__(struct blk_mq_hw_ctx)) !=
2620 sizeof(struct blk_mq_hw_ctx));
2622 if (tag_set->flags & BLK_MQ_F_BLOCKING)
2623 hw_ctx_size += sizeof(struct srcu_struct);
2628 static int blk_mq_init_hctx(struct request_queue *q,
2629 struct blk_mq_tag_set *set,
2630 struct blk_mq_hw_ctx *hctx, unsigned hctx_idx)
2632 hctx->queue_num = hctx_idx;
2634 if (!(hctx->flags & BLK_MQ_F_STACKING))
2635 cpuhp_state_add_instance_nocalls(CPUHP_AP_BLK_MQ_ONLINE,
2636 &hctx->cpuhp_online);
2637 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD, &hctx->cpuhp_dead);
2639 hctx->tags = set->tags[hctx_idx];
2641 if (set->ops->init_hctx &&
2642 set->ops->init_hctx(hctx, set->driver_data, hctx_idx))
2643 goto unregister_cpu_notifier;
2645 if (blk_mq_init_request(set, hctx->fq->flush_rq, hctx_idx,
2651 if (set->ops->exit_hctx)
2652 set->ops->exit_hctx(hctx, hctx_idx);
2653 unregister_cpu_notifier:
2654 blk_mq_remove_cpuhp(hctx);
2658 static struct blk_mq_hw_ctx *
2659 blk_mq_alloc_hctx(struct request_queue *q, struct blk_mq_tag_set *set,
2662 struct blk_mq_hw_ctx *hctx;
2663 gfp_t gfp = GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY;
2665 hctx = kzalloc_node(blk_mq_hw_ctx_size(set), gfp, node);
2667 goto fail_alloc_hctx;
2669 if (!zalloc_cpumask_var_node(&hctx->cpumask, gfp, node))
2672 atomic_set(&hctx->nr_active, 0);
2673 atomic_set(&hctx->elevator_queued, 0);
2674 if (node == NUMA_NO_NODE)
2675 node = set->numa_node;
2676 hctx->numa_node = node;
2678 INIT_DELAYED_WORK(&hctx->run_work, blk_mq_run_work_fn);
2679 spin_lock_init(&hctx->lock);
2680 INIT_LIST_HEAD(&hctx->dispatch);
2682 hctx->flags = set->flags & ~BLK_MQ_F_TAG_QUEUE_SHARED;
2684 INIT_LIST_HEAD(&hctx->hctx_list);
2687 * Allocate space for all possible cpus to avoid allocation at
2690 hctx->ctxs = kmalloc_array_node(nr_cpu_ids, sizeof(void *),
2695 if (sbitmap_init_node(&hctx->ctx_map, nr_cpu_ids, ilog2(8),
2700 spin_lock_init(&hctx->dispatch_wait_lock);
2701 init_waitqueue_func_entry(&hctx->dispatch_wait, blk_mq_dispatch_wake);
2702 INIT_LIST_HEAD(&hctx->dispatch_wait.entry);
2704 hctx->fq = blk_alloc_flush_queue(hctx->numa_node, set->cmd_size, gfp);
2708 if (hctx->flags & BLK_MQ_F_BLOCKING)
2709 init_srcu_struct(hctx->srcu);
2710 blk_mq_hctx_kobj_init(hctx);
2715 sbitmap_free(&hctx->ctx_map);
2719 free_cpumask_var(hctx->cpumask);
2726 static void blk_mq_init_cpu_queues(struct request_queue *q,
2727 unsigned int nr_hw_queues)
2729 struct blk_mq_tag_set *set = q->tag_set;
2732 for_each_possible_cpu(i) {
2733 struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
2734 struct blk_mq_hw_ctx *hctx;
2738 spin_lock_init(&__ctx->lock);
2739 for (k = HCTX_TYPE_DEFAULT; k < HCTX_MAX_TYPES; k++)
2740 INIT_LIST_HEAD(&__ctx->rq_lists[k]);
2745 * Set local node, IFF we have more than one hw queue. If
2746 * not, we remain on the home node of the device
2748 for (j = 0; j < set->nr_maps; j++) {
2749 hctx = blk_mq_map_queue_type(q, j, i);
2750 if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE)
2751 hctx->numa_node = cpu_to_node(i);
2756 static bool __blk_mq_alloc_map_and_request(struct blk_mq_tag_set *set,
2759 unsigned int flags = set->flags;
2762 set->tags[hctx_idx] = blk_mq_alloc_rq_map(set, hctx_idx,
2763 set->queue_depth, set->reserved_tags, flags);
2764 if (!set->tags[hctx_idx])
2767 ret = blk_mq_alloc_rqs(set, set->tags[hctx_idx], hctx_idx,
2772 blk_mq_free_rq_map(set->tags[hctx_idx], flags);
2773 set->tags[hctx_idx] = NULL;
2777 static void blk_mq_free_map_and_requests(struct blk_mq_tag_set *set,
2778 unsigned int hctx_idx)
2780 unsigned int flags = set->flags;
2782 if (set->tags && set->tags[hctx_idx]) {
2783 blk_mq_free_rqs(set, set->tags[hctx_idx], hctx_idx);
2784 blk_mq_free_rq_map(set->tags[hctx_idx], flags);
2785 set->tags[hctx_idx] = NULL;
2789 static void blk_mq_map_swqueue(struct request_queue *q)
2791 unsigned int i, j, hctx_idx;
2792 struct blk_mq_hw_ctx *hctx;
2793 struct blk_mq_ctx *ctx;
2794 struct blk_mq_tag_set *set = q->tag_set;
2796 queue_for_each_hw_ctx(q, hctx, i) {
2797 cpumask_clear(hctx->cpumask);
2799 hctx->dispatch_from = NULL;
2803 * Map software to hardware queues.
2805 * If the cpu isn't present, the cpu is mapped to first hctx.
2807 for_each_possible_cpu(i) {
2809 ctx = per_cpu_ptr(q->queue_ctx, i);
2810 for (j = 0; j < set->nr_maps; j++) {
2811 if (!set->map[j].nr_queues) {
2812 ctx->hctxs[j] = blk_mq_map_queue_type(q,
2813 HCTX_TYPE_DEFAULT, i);
2816 hctx_idx = set->map[j].mq_map[i];
2817 /* unmapped hw queue can be remapped after CPU topo changed */
2818 if (!set->tags[hctx_idx] &&
2819 !__blk_mq_alloc_map_and_request(set, hctx_idx)) {
2821 * If tags initialization fail for some hctx,
2822 * that hctx won't be brought online. In this
2823 * case, remap the current ctx to hctx[0] which
2824 * is guaranteed to always have tags allocated
2826 set->map[j].mq_map[i] = 0;
2829 hctx = blk_mq_map_queue_type(q, j, i);
2830 ctx->hctxs[j] = hctx;
2832 * If the CPU is already set in the mask, then we've
2833 * mapped this one already. This can happen if
2834 * devices share queues across queue maps.
2836 if (cpumask_test_cpu(i, hctx->cpumask))
2839 cpumask_set_cpu(i, hctx->cpumask);
2841 ctx->index_hw[hctx->type] = hctx->nr_ctx;
2842 hctx->ctxs[hctx->nr_ctx++] = ctx;
2845 * If the nr_ctx type overflows, we have exceeded the
2846 * amount of sw queues we can support.
2848 BUG_ON(!hctx->nr_ctx);
2851 for (; j < HCTX_MAX_TYPES; j++)
2852 ctx->hctxs[j] = blk_mq_map_queue_type(q,
2853 HCTX_TYPE_DEFAULT, i);
2856 queue_for_each_hw_ctx(q, hctx, i) {
2858 * If no software queues are mapped to this hardware queue,
2859 * disable it and free the request entries.
2861 if (!hctx->nr_ctx) {
2862 /* Never unmap queue 0. We need it as a
2863 * fallback in case of a new remap fails
2866 if (i && set->tags[i])
2867 blk_mq_free_map_and_requests(set, i);
2873 hctx->tags = set->tags[i];
2874 WARN_ON(!hctx->tags);
2877 * Set the map size to the number of mapped software queues.
2878 * This is more accurate and more efficient than looping
2879 * over all possibly mapped software queues.
2881 sbitmap_resize(&hctx->ctx_map, hctx->nr_ctx);
2884 * Initialize batch roundrobin counts
2886 hctx->next_cpu = blk_mq_first_mapped_cpu(hctx);
2887 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
2892 * Caller needs to ensure that we're either frozen/quiesced, or that
2893 * the queue isn't live yet.
2895 static void queue_set_hctx_shared(struct request_queue *q, bool shared)
2897 struct blk_mq_hw_ctx *hctx;
2900 queue_for_each_hw_ctx(q, hctx, i) {
2902 hctx->flags |= BLK_MQ_F_TAG_QUEUE_SHARED;
2904 hctx->flags &= ~BLK_MQ_F_TAG_QUEUE_SHARED;
2908 static void blk_mq_update_tag_set_shared(struct blk_mq_tag_set *set,
2911 struct request_queue *q;
2913 lockdep_assert_held(&set->tag_list_lock);
2915 list_for_each_entry(q, &set->tag_list, tag_set_list) {
2916 blk_mq_freeze_queue(q);
2917 queue_set_hctx_shared(q, shared);
2918 blk_mq_unfreeze_queue(q);
2922 static void blk_mq_del_queue_tag_set(struct request_queue *q)
2924 struct blk_mq_tag_set *set = q->tag_set;
2926 mutex_lock(&set->tag_list_lock);
2927 list_del(&q->tag_set_list);
2928 if (list_is_singular(&set->tag_list)) {
2929 /* just transitioned to unshared */
2930 set->flags &= ~BLK_MQ_F_TAG_QUEUE_SHARED;
2931 /* update existing queue */
2932 blk_mq_update_tag_set_shared(set, false);
2934 mutex_unlock(&set->tag_list_lock);
2935 INIT_LIST_HEAD(&q->tag_set_list);
2938 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
2939 struct request_queue *q)
2941 mutex_lock(&set->tag_list_lock);
2944 * Check to see if we're transitioning to shared (from 1 to 2 queues).
2946 if (!list_empty(&set->tag_list) &&
2947 !(set->flags & BLK_MQ_F_TAG_QUEUE_SHARED)) {
2948 set->flags |= BLK_MQ_F_TAG_QUEUE_SHARED;
2949 /* update existing queue */
2950 blk_mq_update_tag_set_shared(set, true);
2952 if (set->flags & BLK_MQ_F_TAG_QUEUE_SHARED)
2953 queue_set_hctx_shared(q, true);
2954 list_add_tail(&q->tag_set_list, &set->tag_list);
2956 mutex_unlock(&set->tag_list_lock);
2959 /* All allocations will be freed in release handler of q->mq_kobj */
2960 static int blk_mq_alloc_ctxs(struct request_queue *q)
2962 struct blk_mq_ctxs *ctxs;
2965 ctxs = kzalloc(sizeof(*ctxs), GFP_KERNEL);
2969 ctxs->queue_ctx = alloc_percpu(struct blk_mq_ctx);
2970 if (!ctxs->queue_ctx)
2973 for_each_possible_cpu(cpu) {
2974 struct blk_mq_ctx *ctx = per_cpu_ptr(ctxs->queue_ctx, cpu);
2978 q->mq_kobj = &ctxs->kobj;
2979 q->queue_ctx = ctxs->queue_ctx;
2988 * It is the actual release handler for mq, but we do it from
2989 * request queue's release handler for avoiding use-after-free
2990 * and headache because q->mq_kobj shouldn't have been introduced,
2991 * but we can't group ctx/kctx kobj without it.
2993 void blk_mq_release(struct request_queue *q)
2995 struct blk_mq_hw_ctx *hctx, *next;
2998 queue_for_each_hw_ctx(q, hctx, i)
2999 WARN_ON_ONCE(hctx && list_empty(&hctx->hctx_list));
3001 /* all hctx are in .unused_hctx_list now */
3002 list_for_each_entry_safe(hctx, next, &q->unused_hctx_list, hctx_list) {
3003 list_del_init(&hctx->hctx_list);
3004 kobject_put(&hctx->kobj);
3007 kfree(q->queue_hw_ctx);
3010 * release .mq_kobj and sw queue's kobject now because
3011 * both share lifetime with request queue.
3013 blk_mq_sysfs_deinit(q);
3016 struct request_queue *blk_mq_init_queue_data(struct blk_mq_tag_set *set,
3019 struct request_queue *uninit_q, *q;
3021 uninit_q = blk_alloc_queue(set->numa_node);
3023 return ERR_PTR(-ENOMEM);
3024 uninit_q->queuedata = queuedata;
3027 * Initialize the queue without an elevator. device_add_disk() will do
3028 * the initialization.
3030 q = blk_mq_init_allocated_queue(set, uninit_q, false);
3032 blk_cleanup_queue(uninit_q);
3036 EXPORT_SYMBOL_GPL(blk_mq_init_queue_data);
3038 struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
3040 return blk_mq_init_queue_data(set, NULL);
3042 EXPORT_SYMBOL(blk_mq_init_queue);
3045 * Helper for setting up a queue with mq ops, given queue depth, and
3046 * the passed in mq ops flags.
3048 struct request_queue *blk_mq_init_sq_queue(struct blk_mq_tag_set *set,
3049 const struct blk_mq_ops *ops,
3050 unsigned int queue_depth,
3051 unsigned int set_flags)
3053 struct request_queue *q;
3056 memset(set, 0, sizeof(*set));
3058 set->nr_hw_queues = 1;
3060 set->queue_depth = queue_depth;
3061 set->numa_node = NUMA_NO_NODE;
3062 set->flags = set_flags;
3064 ret = blk_mq_alloc_tag_set(set);
3066 return ERR_PTR(ret);
3068 q = blk_mq_init_queue(set);
3070 blk_mq_free_tag_set(set);
3076 EXPORT_SYMBOL(blk_mq_init_sq_queue);
3078 static struct blk_mq_hw_ctx *blk_mq_alloc_and_init_hctx(
3079 struct blk_mq_tag_set *set, struct request_queue *q,
3080 int hctx_idx, int node)
3082 struct blk_mq_hw_ctx *hctx = NULL, *tmp;
3084 /* reuse dead hctx first */
3085 spin_lock(&q->unused_hctx_lock);
3086 list_for_each_entry(tmp, &q->unused_hctx_list, hctx_list) {
3087 if (tmp->numa_node == node) {
3093 list_del_init(&hctx->hctx_list);
3094 spin_unlock(&q->unused_hctx_lock);
3097 hctx = blk_mq_alloc_hctx(q, set, node);
3101 if (blk_mq_init_hctx(q, set, hctx, hctx_idx))
3107 kobject_put(&hctx->kobj);
3112 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
3113 struct request_queue *q)
3116 struct blk_mq_hw_ctx **hctxs = q->queue_hw_ctx;
3118 if (q->nr_hw_queues < set->nr_hw_queues) {
3119 struct blk_mq_hw_ctx **new_hctxs;
3121 new_hctxs = kcalloc_node(set->nr_hw_queues,
3122 sizeof(*new_hctxs), GFP_KERNEL,
3127 memcpy(new_hctxs, hctxs, q->nr_hw_queues *
3129 q->queue_hw_ctx = new_hctxs;
3134 /* protect against switching io scheduler */
3135 mutex_lock(&q->sysfs_lock);
3136 for (i = 0; i < set->nr_hw_queues; i++) {
3138 struct blk_mq_hw_ctx *hctx;
3140 node = blk_mq_hw_queue_to_node(&set->map[HCTX_TYPE_DEFAULT], i);
3142 * If the hw queue has been mapped to another numa node,
3143 * we need to realloc the hctx. If allocation fails, fallback
3144 * to use the previous one.
3146 if (hctxs[i] && (hctxs[i]->numa_node == node))
3149 hctx = blk_mq_alloc_and_init_hctx(set, q, i, node);
3152 blk_mq_exit_hctx(q, set, hctxs[i], i);
3156 pr_warn("Allocate new hctx on node %d fails,\
3157 fallback to previous one on node %d\n",
3158 node, hctxs[i]->numa_node);
3164 * Increasing nr_hw_queues fails. Free the newly allocated
3165 * hctxs and keep the previous q->nr_hw_queues.
3167 if (i != set->nr_hw_queues) {
3168 j = q->nr_hw_queues;
3172 end = q->nr_hw_queues;
3173 q->nr_hw_queues = set->nr_hw_queues;
3176 for (; j < end; j++) {
3177 struct blk_mq_hw_ctx *hctx = hctxs[j];
3181 blk_mq_free_map_and_requests(set, j);
3182 blk_mq_exit_hctx(q, set, hctx, j);
3186 mutex_unlock(&q->sysfs_lock);
3189 struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
3190 struct request_queue *q,
3193 /* mark the queue as mq asap */
3194 q->mq_ops = set->ops;
3196 q->poll_cb = blk_stat_alloc_callback(blk_mq_poll_stats_fn,
3197 blk_mq_poll_stats_bkt,
3198 BLK_MQ_POLL_STATS_BKTS, q);
3202 if (blk_mq_alloc_ctxs(q))
3205 /* init q->mq_kobj and sw queues' kobjects */
3206 blk_mq_sysfs_init(q);
3208 INIT_LIST_HEAD(&q->unused_hctx_list);
3209 spin_lock_init(&q->unused_hctx_lock);
3211 blk_mq_realloc_hw_ctxs(set, q);
3212 if (!q->nr_hw_queues)
3215 INIT_WORK(&q->timeout_work, blk_mq_timeout_work);
3216 blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);
3220 q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
3221 if (set->nr_maps > HCTX_TYPE_POLL &&
3222 set->map[HCTX_TYPE_POLL].nr_queues)
3223 blk_queue_flag_set(QUEUE_FLAG_POLL, q);
3225 q->sg_reserved_size = INT_MAX;
3227 INIT_DELAYED_WORK(&q->requeue_work, blk_mq_requeue_work);
3228 INIT_LIST_HEAD(&q->requeue_list);
3229 spin_lock_init(&q->requeue_lock);
3231 q->nr_requests = set->queue_depth;
3234 * Default to classic polling
3236 q->poll_nsec = BLK_MQ_POLL_CLASSIC;
3238 blk_mq_init_cpu_queues(q, set->nr_hw_queues);
3239 blk_mq_add_queue_tag_set(set, q);
3240 blk_mq_map_swqueue(q);
3243 elevator_init_mq(q);
3248 kfree(q->queue_hw_ctx);
3249 q->nr_hw_queues = 0;
3250 blk_mq_sysfs_deinit(q);
3252 blk_stat_free_callback(q->poll_cb);
3256 return ERR_PTR(-ENOMEM);
3258 EXPORT_SYMBOL(blk_mq_init_allocated_queue);
3260 /* tags can _not_ be used after returning from blk_mq_exit_queue */
3261 void blk_mq_exit_queue(struct request_queue *q)
3263 struct blk_mq_tag_set *set = q->tag_set;
3265 blk_mq_del_queue_tag_set(q);
3266 blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
3269 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
3273 for (i = 0; i < set->nr_hw_queues; i++) {
3274 if (!__blk_mq_alloc_map_and_request(set, i))
3283 blk_mq_free_map_and_requests(set, i);
3289 * Allocate the request maps associated with this tag_set. Note that this
3290 * may reduce the depth asked for, if memory is tight. set->queue_depth
3291 * will be updated to reflect the allocated depth.
3293 static int blk_mq_alloc_map_and_requests(struct blk_mq_tag_set *set)
3298 depth = set->queue_depth;
3300 err = __blk_mq_alloc_rq_maps(set);
3304 set->queue_depth >>= 1;
3305 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN) {
3309 } while (set->queue_depth);
3311 if (!set->queue_depth || err) {
3312 pr_err("blk-mq: failed to allocate request map\n");
3316 if (depth != set->queue_depth)
3317 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
3318 depth, set->queue_depth);
3323 static int blk_mq_update_queue_map(struct blk_mq_tag_set *set)
3326 * blk_mq_map_queues() and multiple .map_queues() implementations
3327 * expect that set->map[HCTX_TYPE_DEFAULT].nr_queues is set to the
3328 * number of hardware queues.
3330 if (set->nr_maps == 1)
3331 set->map[HCTX_TYPE_DEFAULT].nr_queues = set->nr_hw_queues;
3333 if (set->ops->map_queues && !is_kdump_kernel()) {
3337 * transport .map_queues is usually done in the following
3340 * for (queue = 0; queue < set->nr_hw_queues; queue++) {
3341 * mask = get_cpu_mask(queue)
3342 * for_each_cpu(cpu, mask)
3343 * set->map[x].mq_map[cpu] = queue;
3346 * When we need to remap, the table has to be cleared for
3347 * killing stale mapping since one CPU may not be mapped
3350 for (i = 0; i < set->nr_maps; i++)
3351 blk_mq_clear_mq_map(&set->map[i]);
3353 return set->ops->map_queues(set);
3355 BUG_ON(set->nr_maps > 1);
3356 return blk_mq_map_queues(&set->map[HCTX_TYPE_DEFAULT]);
3360 static int blk_mq_realloc_tag_set_tags(struct blk_mq_tag_set *set,
3361 int cur_nr_hw_queues, int new_nr_hw_queues)
3363 struct blk_mq_tags **new_tags;
3365 if (cur_nr_hw_queues >= new_nr_hw_queues)
3368 new_tags = kcalloc_node(new_nr_hw_queues, sizeof(struct blk_mq_tags *),
3369 GFP_KERNEL, set->numa_node);
3374 memcpy(new_tags, set->tags, cur_nr_hw_queues *
3375 sizeof(*set->tags));
3377 set->tags = new_tags;
3378 set->nr_hw_queues = new_nr_hw_queues;
3383 static int blk_mq_alloc_tag_set_tags(struct blk_mq_tag_set *set,
3384 int new_nr_hw_queues)
3386 return blk_mq_realloc_tag_set_tags(set, 0, new_nr_hw_queues);
3390 * Alloc a tag set to be associated with one or more request queues.
3391 * May fail with EINVAL for various error conditions. May adjust the
3392 * requested depth down, if it's too large. In that case, the set
3393 * value will be stored in set->queue_depth.
3395 int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
3399 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH > 1 << BLK_MQ_UNIQUE_TAG_BITS);
3401 if (!set->nr_hw_queues)
3403 if (!set->queue_depth)
3405 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN)
3408 if (!set->ops->queue_rq)
3411 if (!set->ops->get_budget ^ !set->ops->put_budget)
3414 if (set->queue_depth > BLK_MQ_MAX_DEPTH) {
3415 pr_info("blk-mq: reduced tag depth to %u\n",
3417 set->queue_depth = BLK_MQ_MAX_DEPTH;
3422 else if (set->nr_maps > HCTX_MAX_TYPES)
3426 * If a crashdump is active, then we are potentially in a very
3427 * memory constrained environment. Limit us to 1 queue and
3428 * 64 tags to prevent using too much memory.
3430 if (is_kdump_kernel()) {
3431 set->nr_hw_queues = 1;
3433 set->queue_depth = min(64U, set->queue_depth);
3436 * There is no use for more h/w queues than cpus if we just have
3439 if (set->nr_maps == 1 && set->nr_hw_queues > nr_cpu_ids)
3440 set->nr_hw_queues = nr_cpu_ids;
3442 if (blk_mq_alloc_tag_set_tags(set, set->nr_hw_queues) < 0)
3446 for (i = 0; i < set->nr_maps; i++) {
3447 set->map[i].mq_map = kcalloc_node(nr_cpu_ids,
3448 sizeof(set->map[i].mq_map[0]),
3449 GFP_KERNEL, set->numa_node);
3450 if (!set->map[i].mq_map)
3451 goto out_free_mq_map;
3452 set->map[i].nr_queues = is_kdump_kernel() ? 1 : set->nr_hw_queues;
3455 ret = blk_mq_update_queue_map(set);
3457 goto out_free_mq_map;
3459 ret = blk_mq_alloc_map_and_requests(set);
3461 goto out_free_mq_map;
3463 if (blk_mq_is_sbitmap_shared(set->flags)) {
3464 atomic_set(&set->active_queues_shared_sbitmap, 0);
3466 if (blk_mq_init_shared_sbitmap(set, set->flags)) {
3468 goto out_free_mq_rq_maps;
3472 mutex_init(&set->tag_list_lock);
3473 INIT_LIST_HEAD(&set->tag_list);
3477 out_free_mq_rq_maps:
3478 for (i = 0; i < set->nr_hw_queues; i++)
3479 blk_mq_free_map_and_requests(set, i);
3481 for (i = 0; i < set->nr_maps; i++) {
3482 kfree(set->map[i].mq_map);
3483 set->map[i].mq_map = NULL;
3489 EXPORT_SYMBOL(blk_mq_alloc_tag_set);
3491 void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
3495 for (i = 0; i < set->nr_hw_queues; i++)
3496 blk_mq_free_map_and_requests(set, i);
3498 if (blk_mq_is_sbitmap_shared(set->flags))
3499 blk_mq_exit_shared_sbitmap(set);
3501 for (j = 0; j < set->nr_maps; j++) {
3502 kfree(set->map[j].mq_map);
3503 set->map[j].mq_map = NULL;
3509 EXPORT_SYMBOL(blk_mq_free_tag_set);
3511 int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
3513 struct blk_mq_tag_set *set = q->tag_set;
3514 struct blk_mq_hw_ctx *hctx;
3520 if (q->nr_requests == nr)
3523 blk_mq_freeze_queue(q);
3524 blk_mq_quiesce_queue(q);
3527 queue_for_each_hw_ctx(q, hctx, i) {
3531 * If we're using an MQ scheduler, just update the scheduler
3532 * queue depth. This is similar to what the old code would do.
3534 if (!hctx->sched_tags) {
3535 ret = blk_mq_tag_update_depth(hctx, &hctx->tags, nr,
3537 if (!ret && blk_mq_is_sbitmap_shared(set->flags))
3538 blk_mq_tag_resize_shared_sbitmap(set, nr);
3540 ret = blk_mq_tag_update_depth(hctx, &hctx->sched_tags,
3545 if (q->elevator && q->elevator->type->ops.depth_updated)
3546 q->elevator->type->ops.depth_updated(hctx);
3550 q->nr_requests = nr;
3552 blk_mq_unquiesce_queue(q);
3553 blk_mq_unfreeze_queue(q);
3559 * request_queue and elevator_type pair.
3560 * It is just used by __blk_mq_update_nr_hw_queues to cache
3561 * the elevator_type associated with a request_queue.
3563 struct blk_mq_qe_pair {
3564 struct list_head node;
3565 struct request_queue *q;
3566 struct elevator_type *type;
3570 * Cache the elevator_type in qe pair list and switch the
3571 * io scheduler to 'none'
3573 static bool blk_mq_elv_switch_none(struct list_head *head,
3574 struct request_queue *q)
3576 struct blk_mq_qe_pair *qe;
3581 qe = kmalloc(sizeof(*qe), GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY);
3585 INIT_LIST_HEAD(&qe->node);
3587 qe->type = q->elevator->type;
3588 list_add(&qe->node, head);
3590 mutex_lock(&q->sysfs_lock);
3592 * After elevator_switch_mq, the previous elevator_queue will be
3593 * released by elevator_release. The reference of the io scheduler
3594 * module get by elevator_get will also be put. So we need to get
3595 * a reference of the io scheduler module here to prevent it to be
3598 __module_get(qe->type->elevator_owner);
3599 elevator_switch_mq(q, NULL);
3600 mutex_unlock(&q->sysfs_lock);
3605 static void blk_mq_elv_switch_back(struct list_head *head,
3606 struct request_queue *q)
3608 struct blk_mq_qe_pair *qe;
3609 struct elevator_type *t = NULL;
3611 list_for_each_entry(qe, head, node)
3620 list_del(&qe->node);
3623 mutex_lock(&q->sysfs_lock);
3624 elevator_switch_mq(q, t);
3625 mutex_unlock(&q->sysfs_lock);
3628 static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set,
3631 struct request_queue *q;
3633 int prev_nr_hw_queues;
3635 lockdep_assert_held(&set->tag_list_lock);
3637 if (set->nr_maps == 1 && nr_hw_queues > nr_cpu_ids)
3638 nr_hw_queues = nr_cpu_ids;
3639 if (nr_hw_queues < 1)
3641 if (set->nr_maps == 1 && nr_hw_queues == set->nr_hw_queues)
3644 list_for_each_entry(q, &set->tag_list, tag_set_list)
3645 blk_mq_freeze_queue(q);
3647 * Switch IO scheduler to 'none', cleaning up the data associated
3648 * with the previous scheduler. We will switch back once we are done
3649 * updating the new sw to hw queue mappings.
3651 list_for_each_entry(q, &set->tag_list, tag_set_list)
3652 if (!blk_mq_elv_switch_none(&head, q))
3655 list_for_each_entry(q, &set->tag_list, tag_set_list) {
3656 blk_mq_debugfs_unregister_hctxs(q);
3657 blk_mq_sysfs_unregister(q);
3660 prev_nr_hw_queues = set->nr_hw_queues;
3661 if (blk_mq_realloc_tag_set_tags(set, set->nr_hw_queues, nr_hw_queues) <
3665 set->nr_hw_queues = nr_hw_queues;
3667 blk_mq_update_queue_map(set);
3668 list_for_each_entry(q, &set->tag_list, tag_set_list) {
3669 blk_mq_realloc_hw_ctxs(set, q);
3670 if (q->nr_hw_queues != set->nr_hw_queues) {
3671 pr_warn("Increasing nr_hw_queues to %d fails, fallback to %d\n",
3672 nr_hw_queues, prev_nr_hw_queues);
3673 set->nr_hw_queues = prev_nr_hw_queues;
3674 blk_mq_map_queues(&set->map[HCTX_TYPE_DEFAULT]);
3677 blk_mq_map_swqueue(q);
3681 list_for_each_entry(q, &set->tag_list, tag_set_list) {
3682 blk_mq_sysfs_register(q);
3683 blk_mq_debugfs_register_hctxs(q);
3687 list_for_each_entry(q, &set->tag_list, tag_set_list)
3688 blk_mq_elv_switch_back(&head, q);
3690 list_for_each_entry(q, &set->tag_list, tag_set_list)
3691 blk_mq_unfreeze_queue(q);
3694 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
3696 mutex_lock(&set->tag_list_lock);
3697 __blk_mq_update_nr_hw_queues(set, nr_hw_queues);
3698 mutex_unlock(&set->tag_list_lock);
3700 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues);
3702 /* Enable polling stats and return whether they were already enabled. */
3703 static bool blk_poll_stats_enable(struct request_queue *q)
3705 if (test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
3706 blk_queue_flag_test_and_set(QUEUE_FLAG_POLL_STATS, q))
3708 blk_stat_add_callback(q, q->poll_cb);
3712 static void blk_mq_poll_stats_start(struct request_queue *q)
3715 * We don't arm the callback if polling stats are not enabled or the
3716 * callback is already active.
3718 if (!test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
3719 blk_stat_is_active(q->poll_cb))
3722 blk_stat_activate_msecs(q->poll_cb, 100);
3725 static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb)
3727 struct request_queue *q = cb->data;
3730 for (bucket = 0; bucket < BLK_MQ_POLL_STATS_BKTS; bucket++) {
3731 if (cb->stat[bucket].nr_samples)
3732 q->poll_stat[bucket] = cb->stat[bucket];
3736 static unsigned long blk_mq_poll_nsecs(struct request_queue *q,
3739 unsigned long ret = 0;
3743 * If stats collection isn't on, don't sleep but turn it on for
3746 if (!blk_poll_stats_enable(q))
3750 * As an optimistic guess, use half of the mean service time
3751 * for this type of request. We can (and should) make this smarter.
3752 * For instance, if the completion latencies are tight, we can
3753 * get closer than just half the mean. This is especially
3754 * important on devices where the completion latencies are longer
3755 * than ~10 usec. We do use the stats for the relevant IO size
3756 * if available which does lead to better estimates.
3758 bucket = blk_mq_poll_stats_bkt(rq);
3762 if (q->poll_stat[bucket].nr_samples)
3763 ret = (q->poll_stat[bucket].mean + 1) / 2;
3768 static bool blk_mq_poll_hybrid_sleep(struct request_queue *q,
3771 struct hrtimer_sleeper hs;
3772 enum hrtimer_mode mode;
3776 if (rq->rq_flags & RQF_MQ_POLL_SLEPT)
3780 * If we get here, hybrid polling is enabled. Hence poll_nsec can be:
3782 * 0: use half of prev avg
3783 * >0: use this specific value
3785 if (q->poll_nsec > 0)
3786 nsecs = q->poll_nsec;
3788 nsecs = blk_mq_poll_nsecs(q, rq);
3793 rq->rq_flags |= RQF_MQ_POLL_SLEPT;
3796 * This will be replaced with the stats tracking code, using
3797 * 'avg_completion_time / 2' as the pre-sleep target.
3801 mode = HRTIMER_MODE_REL;
3802 hrtimer_init_sleeper_on_stack(&hs, CLOCK_MONOTONIC, mode);
3803 hrtimer_set_expires(&hs.timer, kt);
3806 if (blk_mq_rq_state(rq) == MQ_RQ_COMPLETE)
3808 set_current_state(TASK_UNINTERRUPTIBLE);
3809 hrtimer_sleeper_start_expires(&hs, mode);
3812 hrtimer_cancel(&hs.timer);
3813 mode = HRTIMER_MODE_ABS;
3814 } while (hs.task && !signal_pending(current));
3816 __set_current_state(TASK_RUNNING);
3817 destroy_hrtimer_on_stack(&hs.timer);
3821 static bool blk_mq_poll_hybrid(struct request_queue *q,
3822 struct blk_mq_hw_ctx *hctx, blk_qc_t cookie)
3826 if (q->poll_nsec == BLK_MQ_POLL_CLASSIC)
3829 if (!blk_qc_t_is_internal(cookie))
3830 rq = blk_mq_tag_to_rq(hctx->tags, blk_qc_t_to_tag(cookie));
3832 rq = blk_mq_tag_to_rq(hctx->sched_tags, blk_qc_t_to_tag(cookie));
3834 * With scheduling, if the request has completed, we'll
3835 * get a NULL return here, as we clear the sched tag when
3836 * that happens. The request still remains valid, like always,
3837 * so we should be safe with just the NULL check.
3843 return blk_mq_poll_hybrid_sleep(q, rq);
3847 * blk_poll - poll for IO completions
3849 * @cookie: cookie passed back at IO submission time
3850 * @spin: whether to spin for completions
3853 * Poll for completions on the passed in queue. Returns number of
3854 * completed entries found. If @spin is true, then blk_poll will continue
3855 * looping until at least one completion is found, unless the task is
3856 * otherwise marked running (or we need to reschedule).
3858 int blk_poll(struct request_queue *q, blk_qc_t cookie, bool spin)
3860 struct blk_mq_hw_ctx *hctx;
3863 if (!blk_qc_t_valid(cookie) ||
3864 !test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
3868 blk_flush_plug_list(current->plug, false);
3870 hctx = q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)];
3873 * If we sleep, have the caller restart the poll loop to reset
3874 * the state. Like for the other success return cases, the
3875 * caller is responsible for checking if the IO completed. If
3876 * the IO isn't complete, we'll get called again and will go
3877 * straight to the busy poll loop. If specified not to spin,
3878 * we also should not sleep.
3880 if (spin && blk_mq_poll_hybrid(q, hctx, cookie))
3883 hctx->poll_considered++;
3885 state = current->state;
3889 hctx->poll_invoked++;
3891 ret = q->mq_ops->poll(hctx);
3893 hctx->poll_success++;
3894 __set_current_state(TASK_RUNNING);
3898 if (signal_pending_state(state, current))
3899 __set_current_state(TASK_RUNNING);
3901 if (current->state == TASK_RUNNING)
3903 if (ret < 0 || !spin)
3906 } while (!need_resched());
3908 __set_current_state(TASK_RUNNING);
3911 EXPORT_SYMBOL_GPL(blk_poll);
3913 unsigned int blk_mq_rq_cpu(struct request *rq)
3915 return rq->mq_ctx->cpu;
3917 EXPORT_SYMBOL(blk_mq_rq_cpu);
3919 static int __init blk_mq_init(void)
3923 for_each_possible_cpu(i)
3924 INIT_LIST_HEAD(&per_cpu(blk_cpu_done, i));
3925 open_softirq(BLOCK_SOFTIRQ, blk_done_softirq);
3927 cpuhp_setup_state_nocalls(CPUHP_BLOCK_SOFTIRQ_DEAD,
3928 "block/softirq:dead", NULL,
3929 blk_softirq_cpu_dead);
3930 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD, "block/mq:dead", NULL,
3931 blk_mq_hctx_notify_dead);
3932 cpuhp_setup_state_multi(CPUHP_AP_BLK_MQ_ONLINE, "block/mq:online",
3933 blk_mq_hctx_notify_online,
3934 blk_mq_hctx_notify_offline);
3937 subsys_initcall(blk_mq_init);