2 * Block multiqueue core code
4 * Copyright (C) 2013-2014 Jens Axboe
5 * Copyright (C) 2013-2014 Christoph Hellwig
7 #include <linux/kernel.h>
8 #include <linux/module.h>
9 #include <linux/backing-dev.h>
10 #include <linux/bio.h>
11 #include <linux/blkdev.h>
12 #include <linux/kmemleak.h>
14 #include <linux/init.h>
15 #include <linux/slab.h>
16 #include <linux/workqueue.h>
17 #include <linux/smp.h>
18 #include <linux/llist.h>
19 #include <linux/list_sort.h>
20 #include <linux/cpu.h>
21 #include <linux/cache.h>
22 #include <linux/sched/sysctl.h>
23 #include <linux/sched/topology.h>
24 #include <linux/sched/signal.h>
25 #include <linux/delay.h>
26 #include <linux/crash_dump.h>
27 #include <linux/prefetch.h>
29 #include <trace/events/block.h>
31 #include <linux/blk-mq.h>
34 #include "blk-mq-tag.h"
37 #include "blk-mq-sched.h"
39 static DEFINE_MUTEX(all_q_mutex);
40 static LIST_HEAD(all_q_list);
43 * Check if any of the ctx's have pending work in this hardware queue
45 bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx)
47 return sbitmap_any_bit_set(&hctx->ctx_map) ||
48 !list_empty_careful(&hctx->dispatch) ||
49 blk_mq_sched_has_work(hctx);
53 * Mark this ctx as having pending work in this hardware queue
55 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx *hctx,
56 struct blk_mq_ctx *ctx)
58 if (!sbitmap_test_bit(&hctx->ctx_map, ctx->index_hw))
59 sbitmap_set_bit(&hctx->ctx_map, ctx->index_hw);
62 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,
63 struct blk_mq_ctx *ctx)
65 sbitmap_clear_bit(&hctx->ctx_map, ctx->index_hw);
68 void blk_mq_freeze_queue_start(struct request_queue *q)
72 freeze_depth = atomic_inc_return(&q->mq_freeze_depth);
73 if (freeze_depth == 1) {
74 percpu_ref_kill(&q->q_usage_counter);
75 blk_mq_run_hw_queues(q, false);
78 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_start);
80 void blk_mq_freeze_queue_wait(struct request_queue *q)
82 wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->q_usage_counter));
84 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait);
86 int blk_mq_freeze_queue_wait_timeout(struct request_queue *q,
87 unsigned long timeout)
89 return wait_event_timeout(q->mq_freeze_wq,
90 percpu_ref_is_zero(&q->q_usage_counter),
93 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout);
96 * Guarantee no request is in use, so we can change any data structure of
97 * the queue afterward.
99 void blk_freeze_queue(struct request_queue *q)
102 * In the !blk_mq case we are only calling this to kill the
103 * q_usage_counter, otherwise this increases the freeze depth
104 * and waits for it to return to zero. For this reason there is
105 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
106 * exported to drivers as the only user for unfreeze is blk_mq.
108 blk_mq_freeze_queue_start(q);
109 blk_mq_freeze_queue_wait(q);
112 void blk_mq_freeze_queue(struct request_queue *q)
115 * ...just an alias to keep freeze and unfreeze actions balanced
116 * in the blk_mq_* namespace
120 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue);
122 void blk_mq_unfreeze_queue(struct request_queue *q)
126 freeze_depth = atomic_dec_return(&q->mq_freeze_depth);
127 WARN_ON_ONCE(freeze_depth < 0);
129 percpu_ref_reinit(&q->q_usage_counter);
130 wake_up_all(&q->mq_freeze_wq);
133 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue);
136 * blk_mq_quiesce_queue() - wait until all ongoing queue_rq calls have finished
139 * Note: this function does not prevent that the struct request end_io()
140 * callback function is invoked. Additionally, it is not prevented that
141 * new queue_rq() calls occur unless the queue has been stopped first.
143 void blk_mq_quiesce_queue(struct request_queue *q)
145 struct blk_mq_hw_ctx *hctx;
149 blk_mq_stop_hw_queues(q);
151 queue_for_each_hw_ctx(q, hctx, i) {
152 if (hctx->flags & BLK_MQ_F_BLOCKING)
153 synchronize_srcu(&hctx->queue_rq_srcu);
160 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue);
162 void blk_mq_wake_waiters(struct request_queue *q)
164 struct blk_mq_hw_ctx *hctx;
167 queue_for_each_hw_ctx(q, hctx, i)
168 if (blk_mq_hw_queue_mapped(hctx))
169 blk_mq_tag_wakeup_all(hctx->tags, true);
172 * If we are called because the queue has now been marked as
173 * dying, we need to ensure that processes currently waiting on
174 * the queue are notified as well.
176 wake_up_all(&q->mq_freeze_wq);
179 bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx)
181 return blk_mq_has_free_tags(hctx->tags);
183 EXPORT_SYMBOL(blk_mq_can_queue);
185 void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx,
186 struct request *rq, unsigned int op)
188 INIT_LIST_HEAD(&rq->queuelist);
189 /* csd/requeue_work/fifo_time is initialized before use */
193 if (blk_queue_io_stat(q))
194 rq->rq_flags |= RQF_IO_STAT;
195 /* do not touch atomic flags, it needs atomic ops against the timer */
197 INIT_HLIST_NODE(&rq->hash);
198 RB_CLEAR_NODE(&rq->rb_node);
201 rq->start_time = jiffies;
202 #ifdef CONFIG_BLK_CGROUP
204 set_start_time_ns(rq);
205 rq->io_start_time_ns = 0;
207 rq->nr_phys_segments = 0;
208 #if defined(CONFIG_BLK_DEV_INTEGRITY)
209 rq->nr_integrity_segments = 0;
212 /* tag was already set */
216 INIT_LIST_HEAD(&rq->timeout_list);
220 rq->end_io_data = NULL;
223 ctx->rq_dispatched[op_is_sync(op)]++;
225 EXPORT_SYMBOL_GPL(blk_mq_rq_ctx_init);
227 struct request *__blk_mq_alloc_request(struct blk_mq_alloc_data *data,
233 tag = blk_mq_get_tag(data);
234 if (tag != BLK_MQ_TAG_FAIL) {
235 struct blk_mq_tags *tags = blk_mq_tags_from_data(data);
237 rq = tags->static_rqs[tag];
239 if (data->flags & BLK_MQ_REQ_INTERNAL) {
241 rq->internal_tag = tag;
243 if (blk_mq_tag_busy(data->hctx)) {
244 rq->rq_flags = RQF_MQ_INFLIGHT;
245 atomic_inc(&data->hctx->nr_active);
248 rq->internal_tag = -1;
249 data->hctx->tags->rqs[rq->tag] = rq;
252 blk_mq_rq_ctx_init(data->q, data->ctx, rq, op);
258 EXPORT_SYMBOL_GPL(__blk_mq_alloc_request);
260 struct request *blk_mq_alloc_request(struct request_queue *q, int rw,
263 struct blk_mq_alloc_data alloc_data = { .flags = flags };
267 ret = blk_queue_enter(q, flags & BLK_MQ_REQ_NOWAIT);
271 rq = blk_mq_sched_get_request(q, NULL, rw, &alloc_data);
273 blk_mq_put_ctx(alloc_data.ctx);
277 return ERR_PTR(-EWOULDBLOCK);
280 rq->__sector = (sector_t) -1;
281 rq->bio = rq->biotail = NULL;
284 EXPORT_SYMBOL(blk_mq_alloc_request);
286 struct request *blk_mq_alloc_request_hctx(struct request_queue *q, int rw,
287 unsigned int flags, unsigned int hctx_idx)
289 struct blk_mq_alloc_data alloc_data = { .flags = flags };
295 * If the tag allocator sleeps we could get an allocation for a
296 * different hardware context. No need to complicate the low level
297 * allocator for this for the rare use case of a command tied to
300 if (WARN_ON_ONCE(!(flags & BLK_MQ_REQ_NOWAIT)))
301 return ERR_PTR(-EINVAL);
303 if (hctx_idx >= q->nr_hw_queues)
304 return ERR_PTR(-EIO);
306 ret = blk_queue_enter(q, true);
311 * Check if the hardware context is actually mapped to anything.
312 * If not tell the caller that it should skip this queue.
314 alloc_data.hctx = q->queue_hw_ctx[hctx_idx];
315 if (!blk_mq_hw_queue_mapped(alloc_data.hctx)) {
317 return ERR_PTR(-EXDEV);
319 cpu = cpumask_first(alloc_data.hctx->cpumask);
320 alloc_data.ctx = __blk_mq_get_ctx(q, cpu);
322 rq = blk_mq_sched_get_request(q, NULL, rw, &alloc_data);
324 blk_mq_put_ctx(alloc_data.ctx);
328 return ERR_PTR(-EWOULDBLOCK);
332 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx);
334 void __blk_mq_finish_request(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
337 const int sched_tag = rq->internal_tag;
338 struct request_queue *q = rq->q;
340 if (rq->rq_flags & RQF_MQ_INFLIGHT)
341 atomic_dec(&hctx->nr_active);
343 wbt_done(q->rq_wb, &rq->issue_stat);
346 clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
347 clear_bit(REQ_ATOM_POLL_SLEPT, &rq->atomic_flags);
349 blk_mq_put_tag(hctx, hctx->tags, ctx, rq->tag);
351 blk_mq_sched_completed_request(hctx, rq);
352 blk_mq_sched_restart_queues(hctx);
356 static void blk_mq_finish_hctx_request(struct blk_mq_hw_ctx *hctx,
359 struct blk_mq_ctx *ctx = rq->mq_ctx;
361 ctx->rq_completed[rq_is_sync(rq)]++;
362 __blk_mq_finish_request(hctx, ctx, rq);
365 void blk_mq_finish_request(struct request *rq)
367 blk_mq_finish_hctx_request(blk_mq_map_queue(rq->q, rq->mq_ctx->cpu), rq);
370 void blk_mq_free_request(struct request *rq)
372 blk_mq_sched_put_request(rq);
374 EXPORT_SYMBOL_GPL(blk_mq_free_request);
376 inline void __blk_mq_end_request(struct request *rq, int error)
378 blk_account_io_done(rq);
381 wbt_done(rq->q->rq_wb, &rq->issue_stat);
382 rq->end_io(rq, error);
384 if (unlikely(blk_bidi_rq(rq)))
385 blk_mq_free_request(rq->next_rq);
386 blk_mq_free_request(rq);
389 EXPORT_SYMBOL(__blk_mq_end_request);
391 void blk_mq_end_request(struct request *rq, int error)
393 if (blk_update_request(rq, error, blk_rq_bytes(rq)))
395 __blk_mq_end_request(rq, error);
397 EXPORT_SYMBOL(blk_mq_end_request);
399 static void __blk_mq_complete_request_remote(void *data)
401 struct request *rq = data;
403 rq->q->softirq_done_fn(rq);
406 static void blk_mq_ipi_complete_request(struct request *rq)
408 struct blk_mq_ctx *ctx = rq->mq_ctx;
412 if (!test_bit(QUEUE_FLAG_SAME_COMP, &rq->q->queue_flags)) {
413 rq->q->softirq_done_fn(rq);
418 if (!test_bit(QUEUE_FLAG_SAME_FORCE, &rq->q->queue_flags))
419 shared = cpus_share_cache(cpu, ctx->cpu);
421 if (cpu != ctx->cpu && !shared && cpu_online(ctx->cpu)) {
422 rq->csd.func = __blk_mq_complete_request_remote;
425 smp_call_function_single_async(ctx->cpu, &rq->csd);
427 rq->q->softirq_done_fn(rq);
432 static void blk_mq_stat_add(struct request *rq)
434 if (rq->rq_flags & RQF_STATS) {
436 * We could rq->mq_ctx here, but there's less of a risk
437 * of races if we have the completion event add the stats
438 * to the local software queue.
440 struct blk_mq_ctx *ctx;
442 ctx = __blk_mq_get_ctx(rq->q, raw_smp_processor_id());
443 blk_stat_add(&ctx->stat[rq_data_dir(rq)], rq);
447 static void __blk_mq_complete_request(struct request *rq)
449 struct request_queue *q = rq->q;
453 if (!q->softirq_done_fn)
454 blk_mq_end_request(rq, rq->errors);
456 blk_mq_ipi_complete_request(rq);
460 * blk_mq_complete_request - end I/O on a request
461 * @rq: the request being processed
464 * Ends all I/O on a request. It does not handle partial completions.
465 * The actual completion happens out-of-order, through a IPI handler.
467 void blk_mq_complete_request(struct request *rq, int error)
469 struct request_queue *q = rq->q;
471 if (unlikely(blk_should_fake_timeout(q)))
473 if (!blk_mark_rq_complete(rq)) {
475 __blk_mq_complete_request(rq);
478 EXPORT_SYMBOL(blk_mq_complete_request);
480 int blk_mq_request_started(struct request *rq)
482 return test_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
484 EXPORT_SYMBOL_GPL(blk_mq_request_started);
486 void blk_mq_start_request(struct request *rq)
488 struct request_queue *q = rq->q;
490 blk_mq_sched_started_request(rq);
492 trace_block_rq_issue(q, rq);
494 if (test_bit(QUEUE_FLAG_STATS, &q->queue_flags)) {
495 blk_stat_set_issue_time(&rq->issue_stat);
496 rq->rq_flags |= RQF_STATS;
497 wbt_issue(q->rq_wb, &rq->issue_stat);
503 * Ensure that ->deadline is visible before set the started
504 * flag and clear the completed flag.
506 smp_mb__before_atomic();
509 * Mark us as started and clear complete. Complete might have been
510 * set if requeue raced with timeout, which then marked it as
511 * complete. So be sure to clear complete again when we start
512 * the request, otherwise we'll ignore the completion event.
514 if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
515 set_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
516 if (test_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags))
517 clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
519 if (q->dma_drain_size && blk_rq_bytes(rq)) {
521 * Make sure space for the drain appears. We know we can do
522 * this because max_hw_segments has been adjusted to be one
523 * fewer than the device can handle.
525 rq->nr_phys_segments++;
528 EXPORT_SYMBOL(blk_mq_start_request);
530 static void __blk_mq_requeue_request(struct request *rq)
532 struct request_queue *q = rq->q;
534 trace_block_rq_requeue(q, rq);
535 wbt_requeue(q->rq_wb, &rq->issue_stat);
536 blk_mq_sched_requeue_request(rq);
538 if (test_and_clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) {
539 if (q->dma_drain_size && blk_rq_bytes(rq))
540 rq->nr_phys_segments--;
544 void blk_mq_requeue_request(struct request *rq, bool kick_requeue_list)
546 __blk_mq_requeue_request(rq);
548 BUG_ON(blk_queued_rq(rq));
549 blk_mq_add_to_requeue_list(rq, true, kick_requeue_list);
551 EXPORT_SYMBOL(blk_mq_requeue_request);
553 static void blk_mq_requeue_work(struct work_struct *work)
555 struct request_queue *q =
556 container_of(work, struct request_queue, requeue_work.work);
558 struct request *rq, *next;
561 spin_lock_irqsave(&q->requeue_lock, flags);
562 list_splice_init(&q->requeue_list, &rq_list);
563 spin_unlock_irqrestore(&q->requeue_lock, flags);
565 list_for_each_entry_safe(rq, next, &rq_list, queuelist) {
566 if (!(rq->rq_flags & RQF_SOFTBARRIER))
569 rq->rq_flags &= ~RQF_SOFTBARRIER;
570 list_del_init(&rq->queuelist);
571 blk_mq_sched_insert_request(rq, true, false, false, true);
574 while (!list_empty(&rq_list)) {
575 rq = list_entry(rq_list.next, struct request, queuelist);
576 list_del_init(&rq->queuelist);
577 blk_mq_sched_insert_request(rq, false, false, false, true);
580 blk_mq_run_hw_queues(q, false);
583 void blk_mq_add_to_requeue_list(struct request *rq, bool at_head,
584 bool kick_requeue_list)
586 struct request_queue *q = rq->q;
590 * We abuse this flag that is otherwise used by the I/O scheduler to
591 * request head insertation from the workqueue.
593 BUG_ON(rq->rq_flags & RQF_SOFTBARRIER);
595 spin_lock_irqsave(&q->requeue_lock, flags);
597 rq->rq_flags |= RQF_SOFTBARRIER;
598 list_add(&rq->queuelist, &q->requeue_list);
600 list_add_tail(&rq->queuelist, &q->requeue_list);
602 spin_unlock_irqrestore(&q->requeue_lock, flags);
604 if (kick_requeue_list)
605 blk_mq_kick_requeue_list(q);
607 EXPORT_SYMBOL(blk_mq_add_to_requeue_list);
609 void blk_mq_kick_requeue_list(struct request_queue *q)
611 kblockd_schedule_delayed_work(&q->requeue_work, 0);
613 EXPORT_SYMBOL(blk_mq_kick_requeue_list);
615 void blk_mq_delay_kick_requeue_list(struct request_queue *q,
618 kblockd_schedule_delayed_work(&q->requeue_work,
619 msecs_to_jiffies(msecs));
621 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list);
623 void blk_mq_abort_requeue_list(struct request_queue *q)
628 spin_lock_irqsave(&q->requeue_lock, flags);
629 list_splice_init(&q->requeue_list, &rq_list);
630 spin_unlock_irqrestore(&q->requeue_lock, flags);
632 while (!list_empty(&rq_list)) {
635 rq = list_first_entry(&rq_list, struct request, queuelist);
636 list_del_init(&rq->queuelist);
638 blk_mq_end_request(rq, rq->errors);
641 EXPORT_SYMBOL(blk_mq_abort_requeue_list);
643 struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
645 if (tag < tags->nr_tags) {
646 prefetch(tags->rqs[tag]);
647 return tags->rqs[tag];
652 EXPORT_SYMBOL(blk_mq_tag_to_rq);
654 struct blk_mq_timeout_data {
656 unsigned int next_set;
659 void blk_mq_rq_timed_out(struct request *req, bool reserved)
661 const struct blk_mq_ops *ops = req->q->mq_ops;
662 enum blk_eh_timer_return ret = BLK_EH_RESET_TIMER;
665 * We know that complete is set at this point. If STARTED isn't set
666 * anymore, then the request isn't active and the "timeout" should
667 * just be ignored. This can happen due to the bitflag ordering.
668 * Timeout first checks if STARTED is set, and if it is, assumes
669 * the request is active. But if we race with completion, then
670 * we both flags will get cleared. So check here again, and ignore
671 * a timeout event with a request that isn't active.
673 if (!test_bit(REQ_ATOM_STARTED, &req->atomic_flags))
677 ret = ops->timeout(req, reserved);
681 __blk_mq_complete_request(req);
683 case BLK_EH_RESET_TIMER:
685 blk_clear_rq_complete(req);
687 case BLK_EH_NOT_HANDLED:
690 printk(KERN_ERR "block: bad eh return: %d\n", ret);
695 static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
696 struct request *rq, void *priv, bool reserved)
698 struct blk_mq_timeout_data *data = priv;
700 if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) {
702 * If a request wasn't started before the queue was
703 * marked dying, kill it here or it'll go unnoticed.
705 if (unlikely(blk_queue_dying(rq->q))) {
707 blk_mq_end_request(rq, rq->errors);
712 if (time_after_eq(jiffies, rq->deadline)) {
713 if (!blk_mark_rq_complete(rq))
714 blk_mq_rq_timed_out(rq, reserved);
715 } else if (!data->next_set || time_after(data->next, rq->deadline)) {
716 data->next = rq->deadline;
721 static void blk_mq_timeout_work(struct work_struct *work)
723 struct request_queue *q =
724 container_of(work, struct request_queue, timeout_work);
725 struct blk_mq_timeout_data data = {
731 /* A deadlock might occur if a request is stuck requiring a
732 * timeout at the same time a queue freeze is waiting
733 * completion, since the timeout code would not be able to
734 * acquire the queue reference here.
736 * That's why we don't use blk_queue_enter here; instead, we use
737 * percpu_ref_tryget directly, because we need to be able to
738 * obtain a reference even in the short window between the queue
739 * starting to freeze, by dropping the first reference in
740 * blk_mq_freeze_queue_start, and the moment the last request is
741 * consumed, marked by the instant q_usage_counter reaches
744 if (!percpu_ref_tryget(&q->q_usage_counter))
747 blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &data);
750 data.next = blk_rq_timeout(round_jiffies_up(data.next));
751 mod_timer(&q->timeout, data.next);
753 struct blk_mq_hw_ctx *hctx;
755 queue_for_each_hw_ctx(q, hctx, i) {
756 /* the hctx may be unmapped, so check it here */
757 if (blk_mq_hw_queue_mapped(hctx))
758 blk_mq_tag_idle(hctx);
765 * Reverse check our software queue for entries that we could potentially
766 * merge with. Currently includes a hand-wavy stop count of 8, to not spend
767 * too much time checking for merges.
769 static bool blk_mq_attempt_merge(struct request_queue *q,
770 struct blk_mq_ctx *ctx, struct bio *bio)
775 list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) {
781 if (!blk_rq_merge_ok(rq, bio))
784 switch (blk_try_merge(rq, bio)) {
785 case ELEVATOR_BACK_MERGE:
786 if (blk_mq_sched_allow_merge(q, rq, bio))
787 merged = bio_attempt_back_merge(q, rq, bio);
789 case ELEVATOR_FRONT_MERGE:
790 if (blk_mq_sched_allow_merge(q, rq, bio))
791 merged = bio_attempt_front_merge(q, rq, bio);
793 case ELEVATOR_DISCARD_MERGE:
794 merged = bio_attempt_discard_merge(q, rq, bio);
808 struct flush_busy_ctx_data {
809 struct blk_mq_hw_ctx *hctx;
810 struct list_head *list;
813 static bool flush_busy_ctx(struct sbitmap *sb, unsigned int bitnr, void *data)
815 struct flush_busy_ctx_data *flush_data = data;
816 struct blk_mq_hw_ctx *hctx = flush_data->hctx;
817 struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
819 sbitmap_clear_bit(sb, bitnr);
820 spin_lock(&ctx->lock);
821 list_splice_tail_init(&ctx->rq_list, flush_data->list);
822 spin_unlock(&ctx->lock);
827 * Process software queues that have been marked busy, splicing them
828 * to the for-dispatch
830 void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list)
832 struct flush_busy_ctx_data data = {
837 sbitmap_for_each_set(&hctx->ctx_map, flush_busy_ctx, &data);
839 EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs);
841 static inline unsigned int queued_to_index(unsigned int queued)
846 return min(BLK_MQ_MAX_DISPATCH_ORDER - 1, ilog2(queued) + 1);
849 bool blk_mq_get_driver_tag(struct request *rq, struct blk_mq_hw_ctx **hctx,
852 struct blk_mq_alloc_data data = {
854 .hctx = blk_mq_map_queue(rq->q, rq->mq_ctx->cpu),
855 .flags = wait ? 0 : BLK_MQ_REQ_NOWAIT,
865 if (blk_mq_tag_is_reserved(data.hctx->sched_tags, rq->internal_tag))
866 data.flags |= BLK_MQ_REQ_RESERVED;
868 rq->tag = blk_mq_get_tag(&data);
870 if (blk_mq_tag_busy(data.hctx)) {
871 rq->rq_flags |= RQF_MQ_INFLIGHT;
872 atomic_inc(&data.hctx->nr_active);
874 data.hctx->tags->rqs[rq->tag] = rq;
881 static void __blk_mq_put_driver_tag(struct blk_mq_hw_ctx *hctx,
884 blk_mq_put_tag(hctx, hctx->tags, rq->mq_ctx, rq->tag);
887 if (rq->rq_flags & RQF_MQ_INFLIGHT) {
888 rq->rq_flags &= ~RQF_MQ_INFLIGHT;
889 atomic_dec(&hctx->nr_active);
893 static void blk_mq_put_driver_tag_hctx(struct blk_mq_hw_ctx *hctx,
896 if (rq->tag == -1 || rq->internal_tag == -1)
899 __blk_mq_put_driver_tag(hctx, rq);
902 static void blk_mq_put_driver_tag(struct request *rq)
904 struct blk_mq_hw_ctx *hctx;
906 if (rq->tag == -1 || rq->internal_tag == -1)
909 hctx = blk_mq_map_queue(rq->q, rq->mq_ctx->cpu);
910 __blk_mq_put_driver_tag(hctx, rq);
914 * If we fail getting a driver tag because all the driver tags are already
915 * assigned and on the dispatch list, BUT the first entry does not have a
916 * tag, then we could deadlock. For that case, move entries with assigned
917 * driver tags to the front, leaving the set of tagged requests in the
918 * same order, and the untagged set in the same order.
920 static bool reorder_tags_to_front(struct list_head *list)
922 struct request *rq, *tmp, *first = NULL;
924 list_for_each_entry_safe_reverse(rq, tmp, list, queuelist) {
928 list_move(&rq->queuelist, list);
934 return first != NULL;
937 static int blk_mq_dispatch_wake(wait_queue_t *wait, unsigned mode, int flags,
940 struct blk_mq_hw_ctx *hctx;
942 hctx = container_of(wait, struct blk_mq_hw_ctx, dispatch_wait);
944 list_del(&wait->task_list);
945 clear_bit_unlock(BLK_MQ_S_TAG_WAITING, &hctx->state);
946 blk_mq_run_hw_queue(hctx, true);
950 static bool blk_mq_dispatch_wait_add(struct blk_mq_hw_ctx *hctx)
952 struct sbq_wait_state *ws;
955 * The TAG_WAITING bit serves as a lock protecting hctx->dispatch_wait.
956 * The thread which wins the race to grab this bit adds the hardware
957 * queue to the wait queue.
959 if (test_bit(BLK_MQ_S_TAG_WAITING, &hctx->state) ||
960 test_and_set_bit_lock(BLK_MQ_S_TAG_WAITING, &hctx->state))
963 init_waitqueue_func_entry(&hctx->dispatch_wait, blk_mq_dispatch_wake);
964 ws = bt_wait_ptr(&hctx->tags->bitmap_tags, hctx);
967 * As soon as this returns, it's no longer safe to fiddle with
968 * hctx->dispatch_wait, since a completion can wake up the wait queue
969 * and unlock the bit.
971 add_wait_queue(&ws->wait, &hctx->dispatch_wait);
975 bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list)
977 struct request_queue *q = hctx->queue;
979 LIST_HEAD(driver_list);
980 struct list_head *dptr;
981 int queued, ret = BLK_MQ_RQ_QUEUE_OK;
984 * Start off with dptr being NULL, so we start the first request
985 * immediately, even if we have more pending.
990 * Now process all the entries, sending them to the driver.
993 while (!list_empty(list)) {
994 struct blk_mq_queue_data bd;
996 rq = list_first_entry(list, struct request, queuelist);
997 if (!blk_mq_get_driver_tag(rq, &hctx, false)) {
998 if (!queued && reorder_tags_to_front(list))
1002 * The initial allocation attempt failed, so we need to
1003 * rerun the hardware queue when a tag is freed.
1005 if (blk_mq_dispatch_wait_add(hctx)) {
1007 * It's possible that a tag was freed in the
1008 * window between the allocation failure and
1009 * adding the hardware queue to the wait queue.
1011 if (!blk_mq_get_driver_tag(rq, &hctx, false))
1018 list_del_init(&rq->queuelist);
1024 * Flag last if we have no more requests, or if we have more
1025 * but can't assign a driver tag to it.
1027 if (list_empty(list))
1030 struct request *nxt;
1032 nxt = list_first_entry(list, struct request, queuelist);
1033 bd.last = !blk_mq_get_driver_tag(nxt, NULL, false);
1036 ret = q->mq_ops->queue_rq(hctx, &bd);
1038 case BLK_MQ_RQ_QUEUE_OK:
1041 case BLK_MQ_RQ_QUEUE_BUSY:
1042 blk_mq_put_driver_tag_hctx(hctx, rq);
1043 list_add(&rq->queuelist, list);
1044 __blk_mq_requeue_request(rq);
1047 pr_err("blk-mq: bad return on queue: %d\n", ret);
1048 case BLK_MQ_RQ_QUEUE_ERROR:
1050 blk_mq_end_request(rq, rq->errors);
1054 if (ret == BLK_MQ_RQ_QUEUE_BUSY)
1058 * We've done the first request. If we have more than 1
1059 * left in the list, set dptr to defer issue.
1061 if (!dptr && list->next != list->prev)
1062 dptr = &driver_list;
1065 hctx->dispatched[queued_to_index(queued)]++;
1068 * Any items that need requeuing? Stuff them into hctx->dispatch,
1069 * that is where we will continue on next queue run.
1071 if (!list_empty(list)) {
1073 * If we got a driver tag for the next request already,
1076 rq = list_first_entry(list, struct request, queuelist);
1077 blk_mq_put_driver_tag(rq);
1079 spin_lock(&hctx->lock);
1080 list_splice_init(list, &hctx->dispatch);
1081 spin_unlock(&hctx->lock);
1084 * the queue is expected stopped with BLK_MQ_RQ_QUEUE_BUSY, but
1085 * it's possible the queue is stopped and restarted again
1086 * before this. Queue restart will dispatch requests. And since
1087 * requests in rq_list aren't added into hctx->dispatch yet,
1088 * the requests in rq_list might get lost.
1090 * blk_mq_run_hw_queue() already checks the STOPPED bit
1092 * If RESTART or TAG_WAITING is set, then let completion restart
1093 * the queue instead of potentially looping here.
1095 if (!blk_mq_sched_needs_restart(hctx) &&
1096 !test_bit(BLK_MQ_S_TAG_WAITING, &hctx->state))
1097 blk_mq_run_hw_queue(hctx, true);
1103 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
1107 WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask) &&
1108 cpu_online(hctx->next_cpu));
1110 if (!(hctx->flags & BLK_MQ_F_BLOCKING)) {
1112 blk_mq_sched_dispatch_requests(hctx);
1115 srcu_idx = srcu_read_lock(&hctx->queue_rq_srcu);
1116 blk_mq_sched_dispatch_requests(hctx);
1117 srcu_read_unlock(&hctx->queue_rq_srcu, srcu_idx);
1122 * It'd be great if the workqueue API had a way to pass
1123 * in a mask and had some smarts for more clever placement.
1124 * For now we just round-robin here, switching for every
1125 * BLK_MQ_CPU_WORK_BATCH queued items.
1127 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
1129 if (hctx->queue->nr_hw_queues == 1)
1130 return WORK_CPU_UNBOUND;
1132 if (--hctx->next_cpu_batch <= 0) {
1135 next_cpu = cpumask_next(hctx->next_cpu, hctx->cpumask);
1136 if (next_cpu >= nr_cpu_ids)
1137 next_cpu = cpumask_first(hctx->cpumask);
1139 hctx->next_cpu = next_cpu;
1140 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
1143 return hctx->next_cpu;
1146 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
1148 if (unlikely(blk_mq_hctx_stopped(hctx) ||
1149 !blk_mq_hw_queue_mapped(hctx)))
1152 if (!async && !(hctx->flags & BLK_MQ_F_BLOCKING)) {
1153 int cpu = get_cpu();
1154 if (cpumask_test_cpu(cpu, hctx->cpumask)) {
1155 __blk_mq_run_hw_queue(hctx);
1163 kblockd_schedule_work_on(blk_mq_hctx_next_cpu(hctx), &hctx->run_work);
1166 void blk_mq_run_hw_queues(struct request_queue *q, bool async)
1168 struct blk_mq_hw_ctx *hctx;
1171 queue_for_each_hw_ctx(q, hctx, i) {
1172 if (!blk_mq_hctx_has_pending(hctx) ||
1173 blk_mq_hctx_stopped(hctx))
1176 blk_mq_run_hw_queue(hctx, async);
1179 EXPORT_SYMBOL(blk_mq_run_hw_queues);
1182 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1183 * @q: request queue.
1185 * The caller is responsible for serializing this function against
1186 * blk_mq_{start,stop}_hw_queue().
1188 bool blk_mq_queue_stopped(struct request_queue *q)
1190 struct blk_mq_hw_ctx *hctx;
1193 queue_for_each_hw_ctx(q, hctx, i)
1194 if (blk_mq_hctx_stopped(hctx))
1199 EXPORT_SYMBOL(blk_mq_queue_stopped);
1201 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
1203 cancel_work(&hctx->run_work);
1204 cancel_delayed_work(&hctx->delay_work);
1205 set_bit(BLK_MQ_S_STOPPED, &hctx->state);
1207 EXPORT_SYMBOL(blk_mq_stop_hw_queue);
1209 void blk_mq_stop_hw_queues(struct request_queue *q)
1211 struct blk_mq_hw_ctx *hctx;
1214 queue_for_each_hw_ctx(q, hctx, i)
1215 blk_mq_stop_hw_queue(hctx);
1217 EXPORT_SYMBOL(blk_mq_stop_hw_queues);
1219 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
1221 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1223 blk_mq_run_hw_queue(hctx, false);
1225 EXPORT_SYMBOL(blk_mq_start_hw_queue);
1227 void blk_mq_start_hw_queues(struct request_queue *q)
1229 struct blk_mq_hw_ctx *hctx;
1232 queue_for_each_hw_ctx(q, hctx, i)
1233 blk_mq_start_hw_queue(hctx);
1235 EXPORT_SYMBOL(blk_mq_start_hw_queues);
1237 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
1239 if (!blk_mq_hctx_stopped(hctx))
1242 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1243 blk_mq_run_hw_queue(hctx, async);
1245 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue);
1247 void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async)
1249 struct blk_mq_hw_ctx *hctx;
1252 queue_for_each_hw_ctx(q, hctx, i)
1253 blk_mq_start_stopped_hw_queue(hctx, async);
1255 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);
1257 static void blk_mq_run_work_fn(struct work_struct *work)
1259 struct blk_mq_hw_ctx *hctx;
1261 hctx = container_of(work, struct blk_mq_hw_ctx, run_work);
1263 __blk_mq_run_hw_queue(hctx);
1266 static void blk_mq_delay_work_fn(struct work_struct *work)
1268 struct blk_mq_hw_ctx *hctx;
1270 hctx = container_of(work, struct blk_mq_hw_ctx, delay_work.work);
1272 if (test_and_clear_bit(BLK_MQ_S_STOPPED, &hctx->state))
1273 __blk_mq_run_hw_queue(hctx);
1276 void blk_mq_delay_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
1278 if (unlikely(!blk_mq_hw_queue_mapped(hctx)))
1281 blk_mq_stop_hw_queue(hctx);
1282 kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
1283 &hctx->delay_work, msecs_to_jiffies(msecs));
1285 EXPORT_SYMBOL(blk_mq_delay_queue);
1287 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx,
1291 struct blk_mq_ctx *ctx = rq->mq_ctx;
1293 trace_block_rq_insert(hctx->queue, rq);
1296 list_add(&rq->queuelist, &ctx->rq_list);
1298 list_add_tail(&rq->queuelist, &ctx->rq_list);
1301 void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
1304 struct blk_mq_ctx *ctx = rq->mq_ctx;
1306 __blk_mq_insert_req_list(hctx, rq, at_head);
1307 blk_mq_hctx_mark_pending(hctx, ctx);
1310 void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
1311 struct list_head *list)
1315 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1318 spin_lock(&ctx->lock);
1319 while (!list_empty(list)) {
1322 rq = list_first_entry(list, struct request, queuelist);
1323 BUG_ON(rq->mq_ctx != ctx);
1324 list_del_init(&rq->queuelist);
1325 __blk_mq_insert_req_list(hctx, rq, false);
1327 blk_mq_hctx_mark_pending(hctx, ctx);
1328 spin_unlock(&ctx->lock);
1331 static int plug_ctx_cmp(void *priv, struct list_head *a, struct list_head *b)
1333 struct request *rqa = container_of(a, struct request, queuelist);
1334 struct request *rqb = container_of(b, struct request, queuelist);
1336 return !(rqa->mq_ctx < rqb->mq_ctx ||
1337 (rqa->mq_ctx == rqb->mq_ctx &&
1338 blk_rq_pos(rqa) < blk_rq_pos(rqb)));
1341 void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
1343 struct blk_mq_ctx *this_ctx;
1344 struct request_queue *this_q;
1347 LIST_HEAD(ctx_list);
1350 list_splice_init(&plug->mq_list, &list);
1352 list_sort(NULL, &list, plug_ctx_cmp);
1358 while (!list_empty(&list)) {
1359 rq = list_entry_rq(list.next);
1360 list_del_init(&rq->queuelist);
1362 if (rq->mq_ctx != this_ctx) {
1364 trace_block_unplug(this_q, depth, from_schedule);
1365 blk_mq_sched_insert_requests(this_q, this_ctx,
1370 this_ctx = rq->mq_ctx;
1376 list_add_tail(&rq->queuelist, &ctx_list);
1380 * If 'this_ctx' is set, we know we have entries to complete
1381 * on 'ctx_list'. Do those.
1384 trace_block_unplug(this_q, depth, from_schedule);
1385 blk_mq_sched_insert_requests(this_q, this_ctx, &ctx_list,
1390 static void blk_mq_bio_to_request(struct request *rq, struct bio *bio)
1392 init_request_from_bio(rq, bio);
1394 blk_account_io_start(rq, true);
1397 static inline bool hctx_allow_merges(struct blk_mq_hw_ctx *hctx)
1399 return (hctx->flags & BLK_MQ_F_SHOULD_MERGE) &&
1400 !blk_queue_nomerges(hctx->queue);
1403 static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx *hctx,
1404 struct blk_mq_ctx *ctx,
1405 struct request *rq, struct bio *bio)
1407 if (!hctx_allow_merges(hctx) || !bio_mergeable(bio)) {
1408 blk_mq_bio_to_request(rq, bio);
1409 spin_lock(&ctx->lock);
1411 __blk_mq_insert_request(hctx, rq, false);
1412 spin_unlock(&ctx->lock);
1415 struct request_queue *q = hctx->queue;
1417 spin_lock(&ctx->lock);
1418 if (!blk_mq_attempt_merge(q, ctx, bio)) {
1419 blk_mq_bio_to_request(rq, bio);
1423 spin_unlock(&ctx->lock);
1424 __blk_mq_finish_request(hctx, ctx, rq);
1429 static blk_qc_t request_to_qc_t(struct blk_mq_hw_ctx *hctx, struct request *rq)
1432 return blk_tag_to_qc_t(rq->tag, hctx->queue_num, false);
1434 return blk_tag_to_qc_t(rq->internal_tag, hctx->queue_num, true);
1437 static void blk_mq_try_issue_directly(struct request *rq, blk_qc_t *cookie)
1439 struct request_queue *q = rq->q;
1440 struct blk_mq_queue_data bd = {
1445 struct blk_mq_hw_ctx *hctx;
1446 blk_qc_t new_cookie;
1452 if (!blk_mq_get_driver_tag(rq, &hctx, false))
1455 new_cookie = request_to_qc_t(hctx, rq);
1458 * For OK queue, we are done. For error, kill it. Any other
1459 * error (busy), just add it to our list as we previously
1462 ret = q->mq_ops->queue_rq(hctx, &bd);
1463 if (ret == BLK_MQ_RQ_QUEUE_OK) {
1464 *cookie = new_cookie;
1468 __blk_mq_requeue_request(rq);
1470 if (ret == BLK_MQ_RQ_QUEUE_ERROR) {
1471 *cookie = BLK_QC_T_NONE;
1473 blk_mq_end_request(rq, rq->errors);
1478 blk_mq_sched_insert_request(rq, false, true, true, false);
1482 * Multiple hardware queue variant. This will not use per-process plugs,
1483 * but will attempt to bypass the hctx queueing if we can go straight to
1484 * hardware for SYNC IO.
1486 static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
1488 const int is_sync = op_is_sync(bio->bi_opf);
1489 const int is_flush_fua = op_is_flush(bio->bi_opf);
1490 struct blk_mq_alloc_data data = { .flags = 0 };
1492 unsigned int request_count = 0, srcu_idx;
1493 struct blk_plug *plug;
1494 struct request *same_queue_rq = NULL;
1496 unsigned int wb_acct;
1498 blk_queue_bounce(q, &bio);
1500 if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
1502 return BLK_QC_T_NONE;
1505 blk_queue_split(q, &bio, q->bio_split);
1507 if (!is_flush_fua && !blk_queue_nomerges(q) &&
1508 blk_attempt_plug_merge(q, bio, &request_count, &same_queue_rq))
1509 return BLK_QC_T_NONE;
1511 if (blk_mq_sched_bio_merge(q, bio))
1512 return BLK_QC_T_NONE;
1514 wb_acct = wbt_wait(q->rq_wb, bio, NULL);
1516 trace_block_getrq(q, bio, bio->bi_opf);
1518 rq = blk_mq_sched_get_request(q, bio, bio->bi_opf, &data);
1519 if (unlikely(!rq)) {
1520 __wbt_done(q->rq_wb, wb_acct);
1521 return BLK_QC_T_NONE;
1524 wbt_track(&rq->issue_stat, wb_acct);
1526 cookie = request_to_qc_t(data.hctx, rq);
1528 if (unlikely(is_flush_fua)) {
1531 blk_mq_bio_to_request(rq, bio);
1532 blk_insert_flush(rq);
1536 plug = current->plug;
1538 * If the driver supports defer issued based on 'last', then
1539 * queue it up like normal since we can potentially save some
1542 if (((plug && !blk_queue_nomerges(q)) || is_sync) &&
1543 !(data.hctx->flags & BLK_MQ_F_DEFER_ISSUE)) {
1544 struct request *old_rq = NULL;
1546 blk_mq_bio_to_request(rq, bio);
1549 * We do limited plugging. If the bio can be merged, do that.
1550 * Otherwise the existing request in the plug list will be
1551 * issued. So the plug list will have one request at most
1555 * The plug list might get flushed before this. If that
1556 * happens, same_queue_rq is invalid and plug list is
1559 if (same_queue_rq && !list_empty(&plug->mq_list)) {
1560 old_rq = same_queue_rq;
1561 list_del_init(&old_rq->queuelist);
1563 list_add_tail(&rq->queuelist, &plug->mq_list);
1564 } else /* is_sync */
1566 blk_mq_put_ctx(data.ctx);
1570 if (!(data.hctx->flags & BLK_MQ_F_BLOCKING)) {
1572 blk_mq_try_issue_directly(old_rq, &cookie);
1575 srcu_idx = srcu_read_lock(&data.hctx->queue_rq_srcu);
1576 blk_mq_try_issue_directly(old_rq, &cookie);
1577 srcu_read_unlock(&data.hctx->queue_rq_srcu, srcu_idx);
1584 blk_mq_put_ctx(data.ctx);
1585 blk_mq_bio_to_request(rq, bio);
1586 blk_mq_sched_insert_request(rq, false, true,
1587 !is_sync || is_flush_fua, true);
1590 if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
1592 * For a SYNC request, send it to the hardware immediately. For
1593 * an ASYNC request, just ensure that we run it later on. The
1594 * latter allows for merging opportunities and more efficient
1598 blk_mq_run_hw_queue(data.hctx, !is_sync || is_flush_fua);
1600 blk_mq_put_ctx(data.ctx);
1606 * Single hardware queue variant. This will attempt to use any per-process
1607 * plug for merging and IO deferral.
1609 static blk_qc_t blk_sq_make_request(struct request_queue *q, struct bio *bio)
1611 const int is_sync = op_is_sync(bio->bi_opf);
1612 const int is_flush_fua = op_is_flush(bio->bi_opf);
1613 struct blk_plug *plug;
1614 unsigned int request_count = 0;
1615 struct blk_mq_alloc_data data = { .flags = 0 };
1618 unsigned int wb_acct;
1620 blk_queue_bounce(q, &bio);
1622 if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
1624 return BLK_QC_T_NONE;
1627 blk_queue_split(q, &bio, q->bio_split);
1629 if (!is_flush_fua && !blk_queue_nomerges(q)) {
1630 if (blk_attempt_plug_merge(q, bio, &request_count, NULL))
1631 return BLK_QC_T_NONE;
1633 request_count = blk_plug_queued_count(q);
1635 if (blk_mq_sched_bio_merge(q, bio))
1636 return BLK_QC_T_NONE;
1638 wb_acct = wbt_wait(q->rq_wb, bio, NULL);
1640 trace_block_getrq(q, bio, bio->bi_opf);
1642 rq = blk_mq_sched_get_request(q, bio, bio->bi_opf, &data);
1643 if (unlikely(!rq)) {
1644 __wbt_done(q->rq_wb, wb_acct);
1645 return BLK_QC_T_NONE;
1648 wbt_track(&rq->issue_stat, wb_acct);
1650 cookie = request_to_qc_t(data.hctx, rq);
1652 if (unlikely(is_flush_fua)) {
1655 blk_mq_bio_to_request(rq, bio);
1656 blk_insert_flush(rq);
1661 * A task plug currently exists. Since this is completely lockless,
1662 * utilize that to temporarily store requests until the task is
1663 * either done or scheduled away.
1665 plug = current->plug;
1667 struct request *last = NULL;
1669 blk_mq_bio_to_request(rq, bio);
1672 * @request_count may become stale because of schedule
1673 * out, so check the list again.
1675 if (list_empty(&plug->mq_list))
1678 trace_block_plug(q);
1680 last = list_entry_rq(plug->mq_list.prev);
1682 blk_mq_put_ctx(data.ctx);
1684 if (request_count >= BLK_MAX_REQUEST_COUNT || (last &&
1685 blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
1686 blk_flush_plug_list(plug, false);
1687 trace_block_plug(q);
1690 list_add_tail(&rq->queuelist, &plug->mq_list);
1696 blk_mq_put_ctx(data.ctx);
1697 blk_mq_bio_to_request(rq, bio);
1698 blk_mq_sched_insert_request(rq, false, true,
1699 !is_sync || is_flush_fua, true);
1702 if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
1704 * For a SYNC request, send it to the hardware immediately. For
1705 * an ASYNC request, just ensure that we run it later on. The
1706 * latter allows for merging opportunities and more efficient
1710 blk_mq_run_hw_queue(data.hctx, !is_sync || is_flush_fua);
1713 blk_mq_put_ctx(data.ctx);
1718 void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
1719 unsigned int hctx_idx)
1723 if (tags->rqs && set->ops->exit_request) {
1726 for (i = 0; i < tags->nr_tags; i++) {
1727 struct request *rq = tags->static_rqs[i];
1731 set->ops->exit_request(set->driver_data, rq,
1733 tags->static_rqs[i] = NULL;
1737 while (!list_empty(&tags->page_list)) {
1738 page = list_first_entry(&tags->page_list, struct page, lru);
1739 list_del_init(&page->lru);
1741 * Remove kmemleak object previously allocated in
1742 * blk_mq_init_rq_map().
1744 kmemleak_free(page_address(page));
1745 __free_pages(page, page->private);
1749 void blk_mq_free_rq_map(struct blk_mq_tags *tags)
1753 kfree(tags->static_rqs);
1754 tags->static_rqs = NULL;
1756 blk_mq_free_tags(tags);
1759 struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set,
1760 unsigned int hctx_idx,
1761 unsigned int nr_tags,
1762 unsigned int reserved_tags)
1764 struct blk_mq_tags *tags;
1767 node = blk_mq_hw_queue_to_node(set->mq_map, hctx_idx);
1768 if (node == NUMA_NO_NODE)
1769 node = set->numa_node;
1771 tags = blk_mq_init_tags(nr_tags, reserved_tags, node,
1772 BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags));
1776 tags->rqs = kzalloc_node(nr_tags * sizeof(struct request *),
1777 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
1780 blk_mq_free_tags(tags);
1784 tags->static_rqs = kzalloc_node(nr_tags * sizeof(struct request *),
1785 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
1787 if (!tags->static_rqs) {
1789 blk_mq_free_tags(tags);
1796 static size_t order_to_size(unsigned int order)
1798 return (size_t)PAGE_SIZE << order;
1801 int blk_mq_alloc_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
1802 unsigned int hctx_idx, unsigned int depth)
1804 unsigned int i, j, entries_per_page, max_order = 4;
1805 size_t rq_size, left;
1808 node = blk_mq_hw_queue_to_node(set->mq_map, hctx_idx);
1809 if (node == NUMA_NO_NODE)
1810 node = set->numa_node;
1812 INIT_LIST_HEAD(&tags->page_list);
1815 * rq_size is the size of the request plus driver payload, rounded
1816 * to the cacheline size
1818 rq_size = round_up(sizeof(struct request) + set->cmd_size,
1820 left = rq_size * depth;
1822 for (i = 0; i < depth; ) {
1823 int this_order = max_order;
1828 while (this_order && left < order_to_size(this_order - 1))
1832 page = alloc_pages_node(node,
1833 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY | __GFP_ZERO,
1839 if (order_to_size(this_order) < rq_size)
1846 page->private = this_order;
1847 list_add_tail(&page->lru, &tags->page_list);
1849 p = page_address(page);
1851 * Allow kmemleak to scan these pages as they contain pointers
1852 * to additional allocations like via ops->init_request().
1854 kmemleak_alloc(p, order_to_size(this_order), 1, GFP_NOIO);
1855 entries_per_page = order_to_size(this_order) / rq_size;
1856 to_do = min(entries_per_page, depth - i);
1857 left -= to_do * rq_size;
1858 for (j = 0; j < to_do; j++) {
1859 struct request *rq = p;
1861 tags->static_rqs[i] = rq;
1862 if (set->ops->init_request) {
1863 if (set->ops->init_request(set->driver_data,
1866 tags->static_rqs[i] = NULL;
1878 blk_mq_free_rqs(set, tags, hctx_idx);
1883 * 'cpu' is going away. splice any existing rq_list entries from this
1884 * software queue to the hw queue dispatch list, and ensure that it
1887 static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node)
1889 struct blk_mq_hw_ctx *hctx;
1890 struct blk_mq_ctx *ctx;
1893 hctx = hlist_entry_safe(node, struct blk_mq_hw_ctx, cpuhp_dead);
1894 ctx = __blk_mq_get_ctx(hctx->queue, cpu);
1896 spin_lock(&ctx->lock);
1897 if (!list_empty(&ctx->rq_list)) {
1898 list_splice_init(&ctx->rq_list, &tmp);
1899 blk_mq_hctx_clear_pending(hctx, ctx);
1901 spin_unlock(&ctx->lock);
1903 if (list_empty(&tmp))
1906 spin_lock(&hctx->lock);
1907 list_splice_tail_init(&tmp, &hctx->dispatch);
1908 spin_unlock(&hctx->lock);
1910 blk_mq_run_hw_queue(hctx, true);
1914 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx *hctx)
1916 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD,
1920 /* hctx->ctxs will be freed in queue's release handler */
1921 static void blk_mq_exit_hctx(struct request_queue *q,
1922 struct blk_mq_tag_set *set,
1923 struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
1925 unsigned flush_start_tag = set->queue_depth;
1927 blk_mq_tag_idle(hctx);
1929 if (set->ops->exit_request)
1930 set->ops->exit_request(set->driver_data,
1931 hctx->fq->flush_rq, hctx_idx,
1932 flush_start_tag + hctx_idx);
1934 if (set->ops->exit_hctx)
1935 set->ops->exit_hctx(hctx, hctx_idx);
1937 if (hctx->flags & BLK_MQ_F_BLOCKING)
1938 cleanup_srcu_struct(&hctx->queue_rq_srcu);
1940 blk_mq_remove_cpuhp(hctx);
1941 blk_free_flush_queue(hctx->fq);
1942 sbitmap_free(&hctx->ctx_map);
1945 static void blk_mq_exit_hw_queues(struct request_queue *q,
1946 struct blk_mq_tag_set *set, int nr_queue)
1948 struct blk_mq_hw_ctx *hctx;
1951 queue_for_each_hw_ctx(q, hctx, i) {
1954 blk_mq_exit_hctx(q, set, hctx, i);
1958 static void blk_mq_free_hw_queues(struct request_queue *q,
1959 struct blk_mq_tag_set *set)
1961 struct blk_mq_hw_ctx *hctx;
1964 queue_for_each_hw_ctx(q, hctx, i)
1965 free_cpumask_var(hctx->cpumask);
1968 static int blk_mq_init_hctx(struct request_queue *q,
1969 struct blk_mq_tag_set *set,
1970 struct blk_mq_hw_ctx *hctx, unsigned hctx_idx)
1973 unsigned flush_start_tag = set->queue_depth;
1975 node = hctx->numa_node;
1976 if (node == NUMA_NO_NODE)
1977 node = hctx->numa_node = set->numa_node;
1979 INIT_WORK(&hctx->run_work, blk_mq_run_work_fn);
1980 INIT_DELAYED_WORK(&hctx->delay_work, blk_mq_delay_work_fn);
1981 spin_lock_init(&hctx->lock);
1982 INIT_LIST_HEAD(&hctx->dispatch);
1984 hctx->queue_num = hctx_idx;
1985 hctx->flags = set->flags & ~BLK_MQ_F_TAG_SHARED;
1987 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD, &hctx->cpuhp_dead);
1989 hctx->tags = set->tags[hctx_idx];
1992 * Allocate space for all possible cpus to avoid allocation at
1995 hctx->ctxs = kmalloc_node(nr_cpu_ids * sizeof(void *),
1998 goto unregister_cpu_notifier;
2000 if (sbitmap_init_node(&hctx->ctx_map, nr_cpu_ids, ilog2(8), GFP_KERNEL,
2006 if (set->ops->init_hctx &&
2007 set->ops->init_hctx(hctx, set->driver_data, hctx_idx))
2010 hctx->fq = blk_alloc_flush_queue(q, hctx->numa_node, set->cmd_size);
2014 if (set->ops->init_request &&
2015 set->ops->init_request(set->driver_data,
2016 hctx->fq->flush_rq, hctx_idx,
2017 flush_start_tag + hctx_idx, node))
2020 if (hctx->flags & BLK_MQ_F_BLOCKING)
2021 init_srcu_struct(&hctx->queue_rq_srcu);
2028 if (set->ops->exit_hctx)
2029 set->ops->exit_hctx(hctx, hctx_idx);
2031 sbitmap_free(&hctx->ctx_map);
2034 unregister_cpu_notifier:
2035 blk_mq_remove_cpuhp(hctx);
2039 static void blk_mq_init_cpu_queues(struct request_queue *q,
2040 unsigned int nr_hw_queues)
2044 for_each_possible_cpu(i) {
2045 struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
2046 struct blk_mq_hw_ctx *hctx;
2048 memset(__ctx, 0, sizeof(*__ctx));
2050 spin_lock_init(&__ctx->lock);
2051 INIT_LIST_HEAD(&__ctx->rq_list);
2053 blk_stat_init(&__ctx->stat[BLK_STAT_READ]);
2054 blk_stat_init(&__ctx->stat[BLK_STAT_WRITE]);
2056 /* If the cpu isn't online, the cpu is mapped to first hctx */
2060 hctx = blk_mq_map_queue(q, i);
2063 * Set local node, IFF we have more than one hw queue. If
2064 * not, we remain on the home node of the device
2066 if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE)
2067 hctx->numa_node = local_memory_node(cpu_to_node(i));
2071 static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set *set, int hctx_idx)
2075 set->tags[hctx_idx] = blk_mq_alloc_rq_map(set, hctx_idx,
2076 set->queue_depth, set->reserved_tags);
2077 if (!set->tags[hctx_idx])
2080 ret = blk_mq_alloc_rqs(set, set->tags[hctx_idx], hctx_idx,
2085 blk_mq_free_rq_map(set->tags[hctx_idx]);
2086 set->tags[hctx_idx] = NULL;
2090 static void blk_mq_free_map_and_requests(struct blk_mq_tag_set *set,
2091 unsigned int hctx_idx)
2093 if (set->tags[hctx_idx]) {
2094 blk_mq_free_rqs(set, set->tags[hctx_idx], hctx_idx);
2095 blk_mq_free_rq_map(set->tags[hctx_idx]);
2096 set->tags[hctx_idx] = NULL;
2100 static void blk_mq_map_swqueue(struct request_queue *q,
2101 const struct cpumask *online_mask)
2103 unsigned int i, hctx_idx;
2104 struct blk_mq_hw_ctx *hctx;
2105 struct blk_mq_ctx *ctx;
2106 struct blk_mq_tag_set *set = q->tag_set;
2109 * Avoid others reading imcomplete hctx->cpumask through sysfs
2111 mutex_lock(&q->sysfs_lock);
2113 queue_for_each_hw_ctx(q, hctx, i) {
2114 cpumask_clear(hctx->cpumask);
2119 * Map software to hardware queues
2121 for_each_possible_cpu(i) {
2122 /* If the cpu isn't online, the cpu is mapped to first hctx */
2123 if (!cpumask_test_cpu(i, online_mask))
2126 hctx_idx = q->mq_map[i];
2127 /* unmapped hw queue can be remapped after CPU topo changed */
2128 if (!set->tags[hctx_idx] &&
2129 !__blk_mq_alloc_rq_map(set, hctx_idx)) {
2131 * If tags initialization fail for some hctx,
2132 * that hctx won't be brought online. In this
2133 * case, remap the current ctx to hctx[0] which
2134 * is guaranteed to always have tags allocated
2139 ctx = per_cpu_ptr(q->queue_ctx, i);
2140 hctx = blk_mq_map_queue(q, i);
2142 cpumask_set_cpu(i, hctx->cpumask);
2143 ctx->index_hw = hctx->nr_ctx;
2144 hctx->ctxs[hctx->nr_ctx++] = ctx;
2147 mutex_unlock(&q->sysfs_lock);
2149 queue_for_each_hw_ctx(q, hctx, i) {
2151 * If no software queues are mapped to this hardware queue,
2152 * disable it and free the request entries.
2154 if (!hctx->nr_ctx) {
2155 /* Never unmap queue 0. We need it as a
2156 * fallback in case of a new remap fails
2159 if (i && set->tags[i])
2160 blk_mq_free_map_and_requests(set, i);
2166 hctx->tags = set->tags[i];
2167 WARN_ON(!hctx->tags);
2170 * Set the map size to the number of mapped software queues.
2171 * This is more accurate and more efficient than looping
2172 * over all possibly mapped software queues.
2174 sbitmap_resize(&hctx->ctx_map, hctx->nr_ctx);
2177 * Initialize batch roundrobin counts
2179 hctx->next_cpu = cpumask_first(hctx->cpumask);
2180 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
2184 static void queue_set_hctx_shared(struct request_queue *q, bool shared)
2186 struct blk_mq_hw_ctx *hctx;
2189 queue_for_each_hw_ctx(q, hctx, i) {
2191 hctx->flags |= BLK_MQ_F_TAG_SHARED;
2193 hctx->flags &= ~BLK_MQ_F_TAG_SHARED;
2197 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set, bool shared)
2199 struct request_queue *q;
2201 list_for_each_entry(q, &set->tag_list, tag_set_list) {
2202 blk_mq_freeze_queue(q);
2203 queue_set_hctx_shared(q, shared);
2204 blk_mq_unfreeze_queue(q);
2208 static void blk_mq_del_queue_tag_set(struct request_queue *q)
2210 struct blk_mq_tag_set *set = q->tag_set;
2212 mutex_lock(&set->tag_list_lock);
2213 list_del_init(&q->tag_set_list);
2214 if (list_is_singular(&set->tag_list)) {
2215 /* just transitioned to unshared */
2216 set->flags &= ~BLK_MQ_F_TAG_SHARED;
2217 /* update existing queue */
2218 blk_mq_update_tag_set_depth(set, false);
2220 mutex_unlock(&set->tag_list_lock);
2223 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
2224 struct request_queue *q)
2228 mutex_lock(&set->tag_list_lock);
2230 /* Check to see if we're transitioning to shared (from 1 to 2 queues). */
2231 if (!list_empty(&set->tag_list) && !(set->flags & BLK_MQ_F_TAG_SHARED)) {
2232 set->flags |= BLK_MQ_F_TAG_SHARED;
2233 /* update existing queue */
2234 blk_mq_update_tag_set_depth(set, true);
2236 if (set->flags & BLK_MQ_F_TAG_SHARED)
2237 queue_set_hctx_shared(q, true);
2238 list_add_tail(&q->tag_set_list, &set->tag_list);
2240 mutex_unlock(&set->tag_list_lock);
2244 * It is the actual release handler for mq, but we do it from
2245 * request queue's release handler for avoiding use-after-free
2246 * and headache because q->mq_kobj shouldn't have been introduced,
2247 * but we can't group ctx/kctx kobj without it.
2249 void blk_mq_release(struct request_queue *q)
2251 struct blk_mq_hw_ctx *hctx;
2254 blk_mq_sched_teardown(q);
2256 /* hctx kobj stays in hctx */
2257 queue_for_each_hw_ctx(q, hctx, i) {
2266 kfree(q->queue_hw_ctx);
2268 /* ctx kobj stays in queue_ctx */
2269 free_percpu(q->queue_ctx);
2272 struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
2274 struct request_queue *uninit_q, *q;
2276 uninit_q = blk_alloc_queue_node(GFP_KERNEL, set->numa_node);
2278 return ERR_PTR(-ENOMEM);
2280 q = blk_mq_init_allocated_queue(set, uninit_q);
2282 blk_cleanup_queue(uninit_q);
2286 EXPORT_SYMBOL(blk_mq_init_queue);
2288 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
2289 struct request_queue *q)
2292 struct blk_mq_hw_ctx **hctxs = q->queue_hw_ctx;
2294 blk_mq_sysfs_unregister(q);
2295 for (i = 0; i < set->nr_hw_queues; i++) {
2301 node = blk_mq_hw_queue_to_node(q->mq_map, i);
2302 hctxs[i] = kzalloc_node(sizeof(struct blk_mq_hw_ctx),
2307 if (!zalloc_cpumask_var_node(&hctxs[i]->cpumask, GFP_KERNEL,
2314 atomic_set(&hctxs[i]->nr_active, 0);
2315 hctxs[i]->numa_node = node;
2316 hctxs[i]->queue_num = i;
2318 if (blk_mq_init_hctx(q, set, hctxs[i], i)) {
2319 free_cpumask_var(hctxs[i]->cpumask);
2324 blk_mq_hctx_kobj_init(hctxs[i]);
2326 for (j = i; j < q->nr_hw_queues; j++) {
2327 struct blk_mq_hw_ctx *hctx = hctxs[j];
2331 blk_mq_free_map_and_requests(set, j);
2332 blk_mq_exit_hctx(q, set, hctx, j);
2333 free_cpumask_var(hctx->cpumask);
2334 kobject_put(&hctx->kobj);
2341 q->nr_hw_queues = i;
2342 blk_mq_sysfs_register(q);
2345 struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
2346 struct request_queue *q)
2348 /* mark the queue as mq asap */
2349 q->mq_ops = set->ops;
2351 q->queue_ctx = alloc_percpu(struct blk_mq_ctx);
2355 q->queue_hw_ctx = kzalloc_node(nr_cpu_ids * sizeof(*(q->queue_hw_ctx)),
2356 GFP_KERNEL, set->numa_node);
2357 if (!q->queue_hw_ctx)
2360 q->mq_map = set->mq_map;
2362 blk_mq_realloc_hw_ctxs(set, q);
2363 if (!q->nr_hw_queues)
2366 INIT_WORK(&q->timeout_work, blk_mq_timeout_work);
2367 blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);
2369 q->nr_queues = nr_cpu_ids;
2371 q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
2373 if (!(set->flags & BLK_MQ_F_SG_MERGE))
2374 q->queue_flags |= 1 << QUEUE_FLAG_NO_SG_MERGE;
2376 q->sg_reserved_size = INT_MAX;
2378 INIT_DELAYED_WORK(&q->requeue_work, blk_mq_requeue_work);
2379 INIT_LIST_HEAD(&q->requeue_list);
2380 spin_lock_init(&q->requeue_lock);
2382 if (q->nr_hw_queues > 1)
2383 blk_queue_make_request(q, blk_mq_make_request);
2385 blk_queue_make_request(q, blk_sq_make_request);
2388 * Do this after blk_queue_make_request() overrides it...
2390 q->nr_requests = set->queue_depth;
2393 * Default to classic polling
2397 if (set->ops->complete)
2398 blk_queue_softirq_done(q, set->ops->complete);
2400 blk_mq_init_cpu_queues(q, set->nr_hw_queues);
2403 mutex_lock(&all_q_mutex);
2405 list_add_tail(&q->all_q_node, &all_q_list);
2406 blk_mq_add_queue_tag_set(set, q);
2407 blk_mq_map_swqueue(q, cpu_online_mask);
2409 mutex_unlock(&all_q_mutex);
2412 if (!(set->flags & BLK_MQ_F_NO_SCHED)) {
2415 ret = blk_mq_sched_init(q);
2417 return ERR_PTR(ret);
2423 kfree(q->queue_hw_ctx);
2425 free_percpu(q->queue_ctx);
2428 return ERR_PTR(-ENOMEM);
2430 EXPORT_SYMBOL(blk_mq_init_allocated_queue);
2432 void blk_mq_free_queue(struct request_queue *q)
2434 struct blk_mq_tag_set *set = q->tag_set;
2436 mutex_lock(&all_q_mutex);
2437 list_del_init(&q->all_q_node);
2438 mutex_unlock(&all_q_mutex);
2442 blk_mq_del_queue_tag_set(q);
2444 blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
2445 blk_mq_free_hw_queues(q, set);
2448 /* Basically redo blk_mq_init_queue with queue frozen */
2449 static void blk_mq_queue_reinit(struct request_queue *q,
2450 const struct cpumask *online_mask)
2452 WARN_ON_ONCE(!atomic_read(&q->mq_freeze_depth));
2454 blk_mq_sysfs_unregister(q);
2457 * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
2458 * we should change hctx numa_node according to new topology (this
2459 * involves free and re-allocate memory, worthy doing?)
2462 blk_mq_map_swqueue(q, online_mask);
2464 blk_mq_sysfs_register(q);
2468 * New online cpumask which is going to be set in this hotplug event.
2469 * Declare this cpumasks as global as cpu-hotplug operation is invoked
2470 * one-by-one and dynamically allocating this could result in a failure.
2472 static struct cpumask cpuhp_online_new;
2474 static void blk_mq_queue_reinit_work(void)
2476 struct request_queue *q;
2478 mutex_lock(&all_q_mutex);
2480 * We need to freeze and reinit all existing queues. Freezing
2481 * involves synchronous wait for an RCU grace period and doing it
2482 * one by one may take a long time. Start freezing all queues in
2483 * one swoop and then wait for the completions so that freezing can
2484 * take place in parallel.
2486 list_for_each_entry(q, &all_q_list, all_q_node)
2487 blk_mq_freeze_queue_start(q);
2488 list_for_each_entry(q, &all_q_list, all_q_node)
2489 blk_mq_freeze_queue_wait(q);
2491 list_for_each_entry(q, &all_q_list, all_q_node)
2492 blk_mq_queue_reinit(q, &cpuhp_online_new);
2494 list_for_each_entry(q, &all_q_list, all_q_node)
2495 blk_mq_unfreeze_queue(q);
2497 mutex_unlock(&all_q_mutex);
2500 static int blk_mq_queue_reinit_dead(unsigned int cpu)
2502 cpumask_copy(&cpuhp_online_new, cpu_online_mask);
2503 blk_mq_queue_reinit_work();
2508 * Before hotadded cpu starts handling requests, new mappings must be
2509 * established. Otherwise, these requests in hw queue might never be
2512 * For example, there is a single hw queue (hctx) and two CPU queues (ctx0
2513 * for CPU0, and ctx1 for CPU1).
2515 * Now CPU1 is just onlined and a request is inserted into ctx1->rq_list
2516 * and set bit0 in pending bitmap as ctx1->index_hw is still zero.
2518 * And then while running hw queue, blk_mq_flush_busy_ctxs() finds bit0 is set
2519 * in pending bitmap and tries to retrieve requests in hctx->ctxs[0]->rq_list.
2520 * But htx->ctxs[0] is a pointer to ctx0, so the request in ctx1->rq_list is
2523 static int blk_mq_queue_reinit_prepare(unsigned int cpu)
2525 cpumask_copy(&cpuhp_online_new, cpu_online_mask);
2526 cpumask_set_cpu(cpu, &cpuhp_online_new);
2527 blk_mq_queue_reinit_work();
2531 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2535 for (i = 0; i < set->nr_hw_queues; i++)
2536 if (!__blk_mq_alloc_rq_map(set, i))
2543 blk_mq_free_rq_map(set->tags[i]);
2549 * Allocate the request maps associated with this tag_set. Note that this
2550 * may reduce the depth asked for, if memory is tight. set->queue_depth
2551 * will be updated to reflect the allocated depth.
2553 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2558 depth = set->queue_depth;
2560 err = __blk_mq_alloc_rq_maps(set);
2564 set->queue_depth >>= 1;
2565 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN) {
2569 } while (set->queue_depth);
2571 if (!set->queue_depth || err) {
2572 pr_err("blk-mq: failed to allocate request map\n");
2576 if (depth != set->queue_depth)
2577 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2578 depth, set->queue_depth);
2584 * Alloc a tag set to be associated with one or more request queues.
2585 * May fail with EINVAL for various error conditions. May adjust the
2586 * requested depth down, if if it too large. In that case, the set
2587 * value will be stored in set->queue_depth.
2589 int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
2593 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH > 1 << BLK_MQ_UNIQUE_TAG_BITS);
2595 if (!set->nr_hw_queues)
2597 if (!set->queue_depth)
2599 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN)
2602 if (!set->ops->queue_rq)
2605 if (set->queue_depth > BLK_MQ_MAX_DEPTH) {
2606 pr_info("blk-mq: reduced tag depth to %u\n",
2608 set->queue_depth = BLK_MQ_MAX_DEPTH;
2612 * If a crashdump is active, then we are potentially in a very
2613 * memory constrained environment. Limit us to 1 queue and
2614 * 64 tags to prevent using too much memory.
2616 if (is_kdump_kernel()) {
2617 set->nr_hw_queues = 1;
2618 set->queue_depth = min(64U, set->queue_depth);
2621 * There is no use for more h/w queues than cpus.
2623 if (set->nr_hw_queues > nr_cpu_ids)
2624 set->nr_hw_queues = nr_cpu_ids;
2626 set->tags = kzalloc_node(nr_cpu_ids * sizeof(struct blk_mq_tags *),
2627 GFP_KERNEL, set->numa_node);
2632 set->mq_map = kzalloc_node(sizeof(*set->mq_map) * nr_cpu_ids,
2633 GFP_KERNEL, set->numa_node);
2637 if (set->ops->map_queues)
2638 ret = set->ops->map_queues(set);
2640 ret = blk_mq_map_queues(set);
2642 goto out_free_mq_map;
2644 ret = blk_mq_alloc_rq_maps(set);
2646 goto out_free_mq_map;
2648 mutex_init(&set->tag_list_lock);
2649 INIT_LIST_HEAD(&set->tag_list);
2661 EXPORT_SYMBOL(blk_mq_alloc_tag_set);
2663 void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
2667 for (i = 0; i < nr_cpu_ids; i++)
2668 blk_mq_free_map_and_requests(set, i);
2676 EXPORT_SYMBOL(blk_mq_free_tag_set);
2678 int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
2680 struct blk_mq_tag_set *set = q->tag_set;
2681 struct blk_mq_hw_ctx *hctx;
2687 blk_mq_freeze_queue(q);
2688 blk_mq_quiesce_queue(q);
2691 queue_for_each_hw_ctx(q, hctx, i) {
2695 * If we're using an MQ scheduler, just update the scheduler
2696 * queue depth. This is similar to what the old code would do.
2698 if (!hctx->sched_tags) {
2699 ret = blk_mq_tag_update_depth(hctx, &hctx->tags,
2700 min(nr, set->queue_depth),
2703 ret = blk_mq_tag_update_depth(hctx, &hctx->sched_tags,
2711 q->nr_requests = nr;
2713 blk_mq_unfreeze_queue(q);
2714 blk_mq_start_stopped_hw_queues(q, true);
2719 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
2721 struct request_queue *q;
2723 if (nr_hw_queues > nr_cpu_ids)
2724 nr_hw_queues = nr_cpu_ids;
2725 if (nr_hw_queues < 1 || nr_hw_queues == set->nr_hw_queues)
2728 list_for_each_entry(q, &set->tag_list, tag_set_list)
2729 blk_mq_freeze_queue(q);
2731 set->nr_hw_queues = nr_hw_queues;
2732 list_for_each_entry(q, &set->tag_list, tag_set_list) {
2733 blk_mq_realloc_hw_ctxs(set, q);
2736 * Manually set the make_request_fn as blk_queue_make_request
2737 * resets a lot of the queue settings.
2739 if (q->nr_hw_queues > 1)
2740 q->make_request_fn = blk_mq_make_request;
2742 q->make_request_fn = blk_sq_make_request;
2744 blk_mq_queue_reinit(q, cpu_online_mask);
2747 list_for_each_entry(q, &set->tag_list, tag_set_list)
2748 blk_mq_unfreeze_queue(q);
2750 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues);
2752 static unsigned long blk_mq_poll_nsecs(struct request_queue *q,
2753 struct blk_mq_hw_ctx *hctx,
2756 struct blk_rq_stat stat[2];
2757 unsigned long ret = 0;
2760 * If stats collection isn't on, don't sleep but turn it on for
2763 if (!blk_stat_enable(q))
2767 * We don't have to do this once per IO, should optimize this
2768 * to just use the current window of stats until it changes
2770 memset(&stat, 0, sizeof(stat));
2771 blk_hctx_stat_get(hctx, stat);
2774 * As an optimistic guess, use half of the mean service time
2775 * for this type of request. We can (and should) make this smarter.
2776 * For instance, if the completion latencies are tight, we can
2777 * get closer than just half the mean. This is especially
2778 * important on devices where the completion latencies are longer
2781 if (req_op(rq) == REQ_OP_READ && stat[BLK_STAT_READ].nr_samples)
2782 ret = (stat[BLK_STAT_READ].mean + 1) / 2;
2783 else if (req_op(rq) == REQ_OP_WRITE && stat[BLK_STAT_WRITE].nr_samples)
2784 ret = (stat[BLK_STAT_WRITE].mean + 1) / 2;
2789 static bool blk_mq_poll_hybrid_sleep(struct request_queue *q,
2790 struct blk_mq_hw_ctx *hctx,
2793 struct hrtimer_sleeper hs;
2794 enum hrtimer_mode mode;
2798 if (test_bit(REQ_ATOM_POLL_SLEPT, &rq->atomic_flags))
2804 * -1: don't ever hybrid sleep
2805 * 0: use half of prev avg
2806 * >0: use this specific value
2808 if (q->poll_nsec == -1)
2810 else if (q->poll_nsec > 0)
2811 nsecs = q->poll_nsec;
2813 nsecs = blk_mq_poll_nsecs(q, hctx, rq);
2818 set_bit(REQ_ATOM_POLL_SLEPT, &rq->atomic_flags);
2821 * This will be replaced with the stats tracking code, using
2822 * 'avg_completion_time / 2' as the pre-sleep target.
2826 mode = HRTIMER_MODE_REL;
2827 hrtimer_init_on_stack(&hs.timer, CLOCK_MONOTONIC, mode);
2828 hrtimer_set_expires(&hs.timer, kt);
2830 hrtimer_init_sleeper(&hs, current);
2832 if (test_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags))
2834 set_current_state(TASK_UNINTERRUPTIBLE);
2835 hrtimer_start_expires(&hs.timer, mode);
2838 hrtimer_cancel(&hs.timer);
2839 mode = HRTIMER_MODE_ABS;
2840 } while (hs.task && !signal_pending(current));
2842 __set_current_state(TASK_RUNNING);
2843 destroy_hrtimer_on_stack(&hs.timer);
2847 static bool __blk_mq_poll(struct blk_mq_hw_ctx *hctx, struct request *rq)
2849 struct request_queue *q = hctx->queue;
2853 * If we sleep, have the caller restart the poll loop to reset
2854 * the state. Like for the other success return cases, the
2855 * caller is responsible for checking if the IO completed. If
2856 * the IO isn't complete, we'll get called again and will go
2857 * straight to the busy poll loop.
2859 if (blk_mq_poll_hybrid_sleep(q, hctx, rq))
2862 hctx->poll_considered++;
2864 state = current->state;
2865 while (!need_resched()) {
2868 hctx->poll_invoked++;
2870 ret = q->mq_ops->poll(hctx, rq->tag);
2872 hctx->poll_success++;
2873 set_current_state(TASK_RUNNING);
2877 if (signal_pending_state(state, current))
2878 set_current_state(TASK_RUNNING);
2880 if (current->state == TASK_RUNNING)
2890 bool blk_mq_poll(struct request_queue *q, blk_qc_t cookie)
2892 struct blk_mq_hw_ctx *hctx;
2893 struct blk_plug *plug;
2896 if (!q->mq_ops || !q->mq_ops->poll || !blk_qc_t_valid(cookie) ||
2897 !test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
2900 plug = current->plug;
2902 blk_flush_plug_list(plug, false);
2904 hctx = q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)];
2905 if (!blk_qc_t_is_internal(cookie))
2906 rq = blk_mq_tag_to_rq(hctx->tags, blk_qc_t_to_tag(cookie));
2908 rq = blk_mq_tag_to_rq(hctx->sched_tags, blk_qc_t_to_tag(cookie));
2910 return __blk_mq_poll(hctx, rq);
2912 EXPORT_SYMBOL_GPL(blk_mq_poll);
2914 void blk_mq_disable_hotplug(void)
2916 mutex_lock(&all_q_mutex);
2919 void blk_mq_enable_hotplug(void)
2921 mutex_unlock(&all_q_mutex);
2924 static int __init blk_mq_init(void)
2926 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD, "block/mq:dead", NULL,
2927 blk_mq_hctx_notify_dead);
2929 cpuhp_setup_state_nocalls(CPUHP_BLK_MQ_PREPARE, "block/mq:prepare",
2930 blk_mq_queue_reinit_prepare,
2931 blk_mq_queue_reinit_dead);
2934 subsys_initcall(blk_mq_init);