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-debugfs.h"
35 #include "blk-mq-tag.h"
38 #include "blk-mq-sched.h"
40 static void blk_mq_poll_stats_start(struct request_queue *q);
41 static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb);
43 static int blk_mq_poll_stats_bkt(const struct request *rq)
45 int ddir, bytes, bucket;
47 ddir = rq_data_dir(rq);
48 bytes = blk_rq_bytes(rq);
50 bucket = ddir + 2*(ilog2(bytes) - 9);
54 else if (bucket >= BLK_MQ_POLL_STATS_BKTS)
55 return ddir + BLK_MQ_POLL_STATS_BKTS - 2;
61 * Check if any of the ctx's have pending work in this hardware queue
63 bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx)
65 return sbitmap_any_bit_set(&hctx->ctx_map) ||
66 !list_empty_careful(&hctx->dispatch) ||
67 blk_mq_sched_has_work(hctx);
71 * Mark this ctx as having pending work in this hardware queue
73 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx *hctx,
74 struct blk_mq_ctx *ctx)
76 if (!sbitmap_test_bit(&hctx->ctx_map, ctx->index_hw))
77 sbitmap_set_bit(&hctx->ctx_map, ctx->index_hw);
80 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,
81 struct blk_mq_ctx *ctx)
83 sbitmap_clear_bit(&hctx->ctx_map, ctx->index_hw);
87 struct hd_struct *part;
88 unsigned int *inflight;
91 static void blk_mq_check_inflight(struct blk_mq_hw_ctx *hctx,
92 struct request *rq, void *priv,
95 struct mq_inflight *mi = priv;
97 if (test_bit(REQ_ATOM_STARTED, &rq->atomic_flags) &&
98 !test_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags)) {
100 * index[0] counts the specific partition that was asked
101 * for. index[1] counts the ones that are active on the
102 * whole device, so increment that if mi->part is indeed
103 * a partition, and not a whole device.
105 if (rq->part == mi->part)
107 if (mi->part->partno)
112 void blk_mq_in_flight(struct request_queue *q, struct hd_struct *part,
113 unsigned int inflight[2])
115 struct mq_inflight mi = { .part = part, .inflight = inflight, };
117 inflight[0] = inflight[1] = 0;
118 blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight, &mi);
121 void blk_freeze_queue_start(struct request_queue *q)
125 freeze_depth = atomic_inc_return(&q->mq_freeze_depth);
126 if (freeze_depth == 1) {
127 percpu_ref_kill(&q->q_usage_counter);
128 blk_mq_run_hw_queues(q, false);
131 EXPORT_SYMBOL_GPL(blk_freeze_queue_start);
133 void blk_mq_freeze_queue_wait(struct request_queue *q)
135 wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->q_usage_counter));
137 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait);
139 int blk_mq_freeze_queue_wait_timeout(struct request_queue *q,
140 unsigned long timeout)
142 return wait_event_timeout(q->mq_freeze_wq,
143 percpu_ref_is_zero(&q->q_usage_counter),
146 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout);
149 * Guarantee no request is in use, so we can change any data structure of
150 * the queue afterward.
152 void blk_freeze_queue(struct request_queue *q)
155 * In the !blk_mq case we are only calling this to kill the
156 * q_usage_counter, otherwise this increases the freeze depth
157 * and waits for it to return to zero. For this reason there is
158 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
159 * exported to drivers as the only user for unfreeze is blk_mq.
161 blk_freeze_queue_start(q);
162 blk_mq_freeze_queue_wait(q);
165 void blk_mq_freeze_queue(struct request_queue *q)
168 * ...just an alias to keep freeze and unfreeze actions balanced
169 * in the blk_mq_* namespace
173 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue);
175 void blk_mq_unfreeze_queue(struct request_queue *q)
179 freeze_depth = atomic_dec_return(&q->mq_freeze_depth);
180 WARN_ON_ONCE(freeze_depth < 0);
182 percpu_ref_reinit(&q->q_usage_counter);
183 wake_up_all(&q->mq_freeze_wq);
186 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue);
189 * FIXME: replace the scsi_internal_device_*block_nowait() calls in the
190 * mpt3sas driver such that this function can be removed.
192 void blk_mq_quiesce_queue_nowait(struct request_queue *q)
196 spin_lock_irqsave(q->queue_lock, flags);
197 queue_flag_set(QUEUE_FLAG_QUIESCED, q);
198 spin_unlock_irqrestore(q->queue_lock, flags);
200 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait);
203 * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished
206 * Note: this function does not prevent that the struct request end_io()
207 * callback function is invoked. Once this function is returned, we make
208 * sure no dispatch can happen until the queue is unquiesced via
209 * blk_mq_unquiesce_queue().
211 void blk_mq_quiesce_queue(struct request_queue *q)
213 struct blk_mq_hw_ctx *hctx;
217 blk_mq_quiesce_queue_nowait(q);
219 queue_for_each_hw_ctx(q, hctx, i) {
220 if (hctx->flags & BLK_MQ_F_BLOCKING)
221 synchronize_srcu(hctx->queue_rq_srcu);
228 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue);
231 * blk_mq_unquiesce_queue() - counterpart of blk_mq_quiesce_queue()
234 * This function recovers queue into the state before quiescing
235 * which is done by blk_mq_quiesce_queue.
237 void blk_mq_unquiesce_queue(struct request_queue *q)
241 spin_lock_irqsave(q->queue_lock, flags);
242 queue_flag_clear(QUEUE_FLAG_QUIESCED, q);
243 spin_unlock_irqrestore(q->queue_lock, flags);
245 /* dispatch requests which are inserted during quiescing */
246 blk_mq_run_hw_queues(q, true);
248 EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue);
250 void blk_mq_wake_waiters(struct request_queue *q)
252 struct blk_mq_hw_ctx *hctx;
255 queue_for_each_hw_ctx(q, hctx, i)
256 if (blk_mq_hw_queue_mapped(hctx))
257 blk_mq_tag_wakeup_all(hctx->tags, true);
260 * If we are called because the queue has now been marked as
261 * dying, we need to ensure that processes currently waiting on
262 * the queue are notified as well.
264 wake_up_all(&q->mq_freeze_wq);
267 bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx)
269 return blk_mq_has_free_tags(hctx->tags);
271 EXPORT_SYMBOL(blk_mq_can_queue);
273 static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
274 unsigned int tag, unsigned int op)
276 struct blk_mq_tags *tags = blk_mq_tags_from_data(data);
277 struct request *rq = tags->static_rqs[tag];
281 if (data->flags & BLK_MQ_REQ_INTERNAL) {
283 rq->internal_tag = tag;
285 if (blk_mq_tag_busy(data->hctx)) {
286 rq->rq_flags = RQF_MQ_INFLIGHT;
287 atomic_inc(&data->hctx->nr_active);
290 rq->internal_tag = -1;
291 data->hctx->tags->rqs[rq->tag] = rq;
294 INIT_LIST_HEAD(&rq->queuelist);
295 /* csd/requeue_work/fifo_time is initialized before use */
297 rq->mq_ctx = data->ctx;
299 if (blk_queue_io_stat(data->q))
300 rq->rq_flags |= RQF_IO_STAT;
301 /* do not touch atomic flags, it needs atomic ops against the timer */
303 INIT_HLIST_NODE(&rq->hash);
304 RB_CLEAR_NODE(&rq->rb_node);
307 rq->start_time = jiffies;
308 #ifdef CONFIG_BLK_CGROUP
310 set_start_time_ns(rq);
311 rq->io_start_time_ns = 0;
313 rq->nr_phys_segments = 0;
314 #if defined(CONFIG_BLK_DEV_INTEGRITY)
315 rq->nr_integrity_segments = 0;
318 /* tag was already set */
321 INIT_LIST_HEAD(&rq->timeout_list);
325 rq->end_io_data = NULL;
328 data->ctx->rq_dispatched[op_is_sync(op)]++;
332 static struct request *blk_mq_get_request(struct request_queue *q,
333 struct bio *bio, unsigned int op,
334 struct blk_mq_alloc_data *data)
336 struct elevator_queue *e = q->elevator;
339 struct blk_mq_ctx *local_ctx = NULL;
341 blk_queue_enter_live(q);
343 if (likely(!data->ctx))
344 data->ctx = local_ctx = blk_mq_get_ctx(q);
345 if (likely(!data->hctx))
346 data->hctx = blk_mq_map_queue(q, data->ctx->cpu);
348 data->flags |= BLK_MQ_REQ_NOWAIT;
351 data->flags |= BLK_MQ_REQ_INTERNAL;
354 * Flush requests are special and go directly to the
357 if (!op_is_flush(op) && e->type->ops.mq.limit_depth)
358 e->type->ops.mq.limit_depth(op, data);
361 tag = blk_mq_get_tag(data);
362 if (tag == BLK_MQ_TAG_FAIL) {
364 blk_mq_put_ctx(local_ctx);
371 rq = blk_mq_rq_ctx_init(data, tag, op);
372 if (!op_is_flush(op)) {
374 if (e && e->type->ops.mq.prepare_request) {
375 if (e->type->icq_cache && rq_ioc(bio))
376 blk_mq_sched_assign_ioc(rq, bio);
378 e->type->ops.mq.prepare_request(rq, bio);
379 rq->rq_flags |= RQF_ELVPRIV;
382 data->hctx->queued++;
386 struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op,
389 struct blk_mq_alloc_data alloc_data = { .flags = flags };
393 ret = blk_queue_enter(q, flags & BLK_MQ_REQ_NOWAIT);
397 rq = blk_mq_get_request(q, NULL, op, &alloc_data);
401 return ERR_PTR(-EWOULDBLOCK);
403 blk_mq_put_ctx(alloc_data.ctx);
406 rq->__sector = (sector_t) -1;
407 rq->bio = rq->biotail = NULL;
410 EXPORT_SYMBOL(blk_mq_alloc_request);
412 struct request *blk_mq_alloc_request_hctx(struct request_queue *q,
413 unsigned int op, unsigned int flags, unsigned int hctx_idx)
415 struct blk_mq_alloc_data alloc_data = { .flags = flags };
421 * If the tag allocator sleeps we could get an allocation for a
422 * different hardware context. No need to complicate the low level
423 * allocator for this for the rare use case of a command tied to
426 if (WARN_ON_ONCE(!(flags & BLK_MQ_REQ_NOWAIT)))
427 return ERR_PTR(-EINVAL);
429 if (hctx_idx >= q->nr_hw_queues)
430 return ERR_PTR(-EIO);
432 ret = blk_queue_enter(q, true);
437 * Check if the hardware context is actually mapped to anything.
438 * If not tell the caller that it should skip this queue.
440 alloc_data.hctx = q->queue_hw_ctx[hctx_idx];
441 if (!blk_mq_hw_queue_mapped(alloc_data.hctx)) {
443 return ERR_PTR(-EXDEV);
445 cpu = cpumask_first(alloc_data.hctx->cpumask);
446 alloc_data.ctx = __blk_mq_get_ctx(q, cpu);
448 rq = blk_mq_get_request(q, NULL, op, &alloc_data);
452 return ERR_PTR(-EWOULDBLOCK);
456 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx);
458 void blk_mq_free_request(struct request *rq)
460 struct request_queue *q = rq->q;
461 struct elevator_queue *e = q->elevator;
462 struct blk_mq_ctx *ctx = rq->mq_ctx;
463 struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
464 const int sched_tag = rq->internal_tag;
466 if (rq->rq_flags & RQF_ELVPRIV) {
467 if (e && e->type->ops.mq.finish_request)
468 e->type->ops.mq.finish_request(rq);
470 put_io_context(rq->elv.icq->ioc);
475 ctx->rq_completed[rq_is_sync(rq)]++;
476 if (rq->rq_flags & RQF_MQ_INFLIGHT)
477 atomic_dec(&hctx->nr_active);
479 wbt_done(q->rq_wb, &rq->issue_stat);
481 clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
482 clear_bit(REQ_ATOM_POLL_SLEPT, &rq->atomic_flags);
484 blk_mq_put_tag(hctx, hctx->tags, ctx, rq->tag);
486 blk_mq_put_tag(hctx, hctx->sched_tags, ctx, sched_tag);
487 blk_mq_sched_restart(hctx);
490 EXPORT_SYMBOL_GPL(blk_mq_free_request);
492 inline void __blk_mq_end_request(struct request *rq, blk_status_t error)
494 blk_account_io_done(rq);
497 wbt_done(rq->q->rq_wb, &rq->issue_stat);
498 rq->end_io(rq, error);
500 if (unlikely(blk_bidi_rq(rq)))
501 blk_mq_free_request(rq->next_rq);
502 blk_mq_free_request(rq);
505 EXPORT_SYMBOL(__blk_mq_end_request);
507 void blk_mq_end_request(struct request *rq, blk_status_t error)
509 if (blk_update_request(rq, error, blk_rq_bytes(rq)))
511 __blk_mq_end_request(rq, error);
513 EXPORT_SYMBOL(blk_mq_end_request);
515 static void __blk_mq_complete_request_remote(void *data)
517 struct request *rq = data;
519 rq->q->softirq_done_fn(rq);
522 static void __blk_mq_complete_request(struct request *rq)
524 struct blk_mq_ctx *ctx = rq->mq_ctx;
528 if (rq->internal_tag != -1)
529 blk_mq_sched_completed_request(rq);
530 if (rq->rq_flags & RQF_STATS) {
531 blk_mq_poll_stats_start(rq->q);
535 if (!test_bit(QUEUE_FLAG_SAME_COMP, &rq->q->queue_flags)) {
536 rq->q->softirq_done_fn(rq);
541 if (!test_bit(QUEUE_FLAG_SAME_FORCE, &rq->q->queue_flags))
542 shared = cpus_share_cache(cpu, ctx->cpu);
544 if (cpu != ctx->cpu && !shared && cpu_online(ctx->cpu)) {
545 rq->csd.func = __blk_mq_complete_request_remote;
548 smp_call_function_single_async(ctx->cpu, &rq->csd);
550 rq->q->softirq_done_fn(rq);
556 * blk_mq_complete_request - end I/O on a request
557 * @rq: the request being processed
560 * Ends all I/O on a request. It does not handle partial completions.
561 * The actual completion happens out-of-order, through a IPI handler.
563 void blk_mq_complete_request(struct request *rq)
565 struct request_queue *q = rq->q;
567 if (unlikely(blk_should_fake_timeout(q)))
569 if (!blk_mark_rq_complete(rq))
570 __blk_mq_complete_request(rq);
572 EXPORT_SYMBOL(blk_mq_complete_request);
574 int blk_mq_request_started(struct request *rq)
576 return test_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
578 EXPORT_SYMBOL_GPL(blk_mq_request_started);
580 void blk_mq_start_request(struct request *rq)
582 struct request_queue *q = rq->q;
584 blk_mq_sched_started_request(rq);
586 trace_block_rq_issue(q, rq);
588 if (test_bit(QUEUE_FLAG_STATS, &q->queue_flags)) {
589 blk_stat_set_issue(&rq->issue_stat, blk_rq_sectors(rq));
590 rq->rq_flags |= RQF_STATS;
591 wbt_issue(q->rq_wb, &rq->issue_stat);
597 * Ensure that ->deadline is visible before set the started
598 * flag and clear the completed flag.
600 smp_mb__before_atomic();
603 * Mark us as started and clear complete. Complete might have been
604 * set if requeue raced with timeout, which then marked it as
605 * complete. So be sure to clear complete again when we start
606 * the request, otherwise we'll ignore the completion event.
608 if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
609 set_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
610 if (test_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags))
611 clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
613 if (q->dma_drain_size && blk_rq_bytes(rq)) {
615 * Make sure space for the drain appears. We know we can do
616 * this because max_hw_segments has been adjusted to be one
617 * fewer than the device can handle.
619 rq->nr_phys_segments++;
622 EXPORT_SYMBOL(blk_mq_start_request);
625 * When we reach here because queue is busy, REQ_ATOM_COMPLETE
626 * flag isn't set yet, so there may be race with timeout handler,
627 * but given rq->deadline is just set in .queue_rq() under
628 * this situation, the race won't be possible in reality because
629 * rq->timeout should be set as big enough to cover the window
630 * between blk_mq_start_request() called from .queue_rq() and
631 * clearing REQ_ATOM_STARTED here.
633 static void __blk_mq_requeue_request(struct request *rq)
635 struct request_queue *q = rq->q;
637 trace_block_rq_requeue(q, rq);
638 wbt_requeue(q->rq_wb, &rq->issue_stat);
639 blk_mq_sched_requeue_request(rq);
641 if (test_and_clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) {
642 if (q->dma_drain_size && blk_rq_bytes(rq))
643 rq->nr_phys_segments--;
647 void blk_mq_requeue_request(struct request *rq, bool kick_requeue_list)
649 __blk_mq_requeue_request(rq);
651 BUG_ON(blk_queued_rq(rq));
652 blk_mq_add_to_requeue_list(rq, true, kick_requeue_list);
654 EXPORT_SYMBOL(blk_mq_requeue_request);
656 static void blk_mq_requeue_work(struct work_struct *work)
658 struct request_queue *q =
659 container_of(work, struct request_queue, requeue_work.work);
661 struct request *rq, *next;
663 spin_lock_irq(&q->requeue_lock);
664 list_splice_init(&q->requeue_list, &rq_list);
665 spin_unlock_irq(&q->requeue_lock);
667 list_for_each_entry_safe(rq, next, &rq_list, queuelist) {
668 if (!(rq->rq_flags & RQF_SOFTBARRIER))
671 rq->rq_flags &= ~RQF_SOFTBARRIER;
672 list_del_init(&rq->queuelist);
673 blk_mq_sched_insert_request(rq, true, false, false, true);
676 while (!list_empty(&rq_list)) {
677 rq = list_entry(rq_list.next, struct request, queuelist);
678 list_del_init(&rq->queuelist);
679 blk_mq_sched_insert_request(rq, false, false, false, true);
682 blk_mq_run_hw_queues(q, false);
685 void blk_mq_add_to_requeue_list(struct request *rq, bool at_head,
686 bool kick_requeue_list)
688 struct request_queue *q = rq->q;
692 * We abuse this flag that is otherwise used by the I/O scheduler to
693 * request head insertation from the workqueue.
695 BUG_ON(rq->rq_flags & RQF_SOFTBARRIER);
697 spin_lock_irqsave(&q->requeue_lock, flags);
699 rq->rq_flags |= RQF_SOFTBARRIER;
700 list_add(&rq->queuelist, &q->requeue_list);
702 list_add_tail(&rq->queuelist, &q->requeue_list);
704 spin_unlock_irqrestore(&q->requeue_lock, flags);
706 if (kick_requeue_list)
707 blk_mq_kick_requeue_list(q);
709 EXPORT_SYMBOL(blk_mq_add_to_requeue_list);
711 void blk_mq_kick_requeue_list(struct request_queue *q)
713 kblockd_schedule_delayed_work(&q->requeue_work, 0);
715 EXPORT_SYMBOL(blk_mq_kick_requeue_list);
717 void blk_mq_delay_kick_requeue_list(struct request_queue *q,
720 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND, &q->requeue_work,
721 msecs_to_jiffies(msecs));
723 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list);
725 struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
727 if (tag < tags->nr_tags) {
728 prefetch(tags->rqs[tag]);
729 return tags->rqs[tag];
734 EXPORT_SYMBOL(blk_mq_tag_to_rq);
736 struct blk_mq_timeout_data {
738 unsigned int next_set;
741 void blk_mq_rq_timed_out(struct request *req, bool reserved)
743 const struct blk_mq_ops *ops = req->q->mq_ops;
744 enum blk_eh_timer_return ret = BLK_EH_RESET_TIMER;
747 * We know that complete is set at this point. If STARTED isn't set
748 * anymore, then the request isn't active and the "timeout" should
749 * just be ignored. This can happen due to the bitflag ordering.
750 * Timeout first checks if STARTED is set, and if it is, assumes
751 * the request is active. But if we race with completion, then
752 * both flags will get cleared. So check here again, and ignore
753 * a timeout event with a request that isn't active.
755 if (!test_bit(REQ_ATOM_STARTED, &req->atomic_flags))
759 ret = ops->timeout(req, reserved);
763 __blk_mq_complete_request(req);
765 case BLK_EH_RESET_TIMER:
767 blk_clear_rq_complete(req);
769 case BLK_EH_NOT_HANDLED:
772 printk(KERN_ERR "block: bad eh return: %d\n", ret);
777 static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
778 struct request *rq, void *priv, bool reserved)
780 struct blk_mq_timeout_data *data = priv;
782 if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
786 * The rq being checked may have been freed and reallocated
787 * out already here, we avoid this race by checking rq->deadline
788 * and REQ_ATOM_COMPLETE flag together:
790 * - if rq->deadline is observed as new value because of
791 * reusing, the rq won't be timed out because of timing.
792 * - if rq->deadline is observed as previous value,
793 * REQ_ATOM_COMPLETE flag won't be cleared in reuse path
794 * because we put a barrier between setting rq->deadline
795 * and clearing the flag in blk_mq_start_request(), so
796 * this rq won't be timed out too.
798 if (time_after_eq(jiffies, rq->deadline)) {
799 if (!blk_mark_rq_complete(rq))
800 blk_mq_rq_timed_out(rq, reserved);
801 } else if (!data->next_set || time_after(data->next, rq->deadline)) {
802 data->next = rq->deadline;
807 static void blk_mq_timeout_work(struct work_struct *work)
809 struct request_queue *q =
810 container_of(work, struct request_queue, timeout_work);
811 struct blk_mq_timeout_data data = {
817 /* A deadlock might occur if a request is stuck requiring a
818 * timeout at the same time a queue freeze is waiting
819 * completion, since the timeout code would not be able to
820 * acquire the queue reference here.
822 * That's why we don't use blk_queue_enter here; instead, we use
823 * percpu_ref_tryget directly, because we need to be able to
824 * obtain a reference even in the short window between the queue
825 * starting to freeze, by dropping the first reference in
826 * blk_freeze_queue_start, and the moment the last request is
827 * consumed, marked by the instant q_usage_counter reaches
830 if (!percpu_ref_tryget(&q->q_usage_counter))
833 blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &data);
836 data.next = blk_rq_timeout(round_jiffies_up(data.next));
837 mod_timer(&q->timeout, data.next);
839 struct blk_mq_hw_ctx *hctx;
841 queue_for_each_hw_ctx(q, hctx, i) {
842 /* the hctx may be unmapped, so check it here */
843 if (blk_mq_hw_queue_mapped(hctx))
844 blk_mq_tag_idle(hctx);
850 struct flush_busy_ctx_data {
851 struct blk_mq_hw_ctx *hctx;
852 struct list_head *list;
855 static bool flush_busy_ctx(struct sbitmap *sb, unsigned int bitnr, void *data)
857 struct flush_busy_ctx_data *flush_data = data;
858 struct blk_mq_hw_ctx *hctx = flush_data->hctx;
859 struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
861 sbitmap_clear_bit(sb, bitnr);
862 spin_lock(&ctx->lock);
863 list_splice_tail_init(&ctx->rq_list, flush_data->list);
864 spin_unlock(&ctx->lock);
869 * Process software queues that have been marked busy, splicing them
870 * to the for-dispatch
872 void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list)
874 struct flush_busy_ctx_data data = {
879 sbitmap_for_each_set(&hctx->ctx_map, flush_busy_ctx, &data);
881 EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs);
883 static inline unsigned int queued_to_index(unsigned int queued)
888 return min(BLK_MQ_MAX_DISPATCH_ORDER - 1, ilog2(queued) + 1);
891 bool blk_mq_get_driver_tag(struct request *rq, struct blk_mq_hw_ctx **hctx,
894 struct blk_mq_alloc_data data = {
896 .hctx = blk_mq_map_queue(rq->q, rq->mq_ctx->cpu),
897 .flags = wait ? 0 : BLK_MQ_REQ_NOWAIT,
900 might_sleep_if(wait);
905 if (blk_mq_tag_is_reserved(data.hctx->sched_tags, rq->internal_tag))
906 data.flags |= BLK_MQ_REQ_RESERVED;
908 rq->tag = blk_mq_get_tag(&data);
910 if (blk_mq_tag_busy(data.hctx)) {
911 rq->rq_flags |= RQF_MQ_INFLIGHT;
912 atomic_inc(&data.hctx->nr_active);
914 data.hctx->tags->rqs[rq->tag] = rq;
920 return rq->tag != -1;
923 static void __blk_mq_put_driver_tag(struct blk_mq_hw_ctx *hctx,
926 blk_mq_put_tag(hctx, hctx->tags, rq->mq_ctx, rq->tag);
929 if (rq->rq_flags & RQF_MQ_INFLIGHT) {
930 rq->rq_flags &= ~RQF_MQ_INFLIGHT;
931 atomic_dec(&hctx->nr_active);
935 static void blk_mq_put_driver_tag_hctx(struct blk_mq_hw_ctx *hctx,
938 if (rq->tag == -1 || rq->internal_tag == -1)
941 __blk_mq_put_driver_tag(hctx, rq);
944 static void blk_mq_put_driver_tag(struct request *rq)
946 struct blk_mq_hw_ctx *hctx;
948 if (rq->tag == -1 || rq->internal_tag == -1)
951 hctx = blk_mq_map_queue(rq->q, rq->mq_ctx->cpu);
952 __blk_mq_put_driver_tag(hctx, rq);
956 * If we fail getting a driver tag because all the driver tags are already
957 * assigned and on the dispatch list, BUT the first entry does not have a
958 * tag, then we could deadlock. For that case, move entries with assigned
959 * driver tags to the front, leaving the set of tagged requests in the
960 * same order, and the untagged set in the same order.
962 static bool reorder_tags_to_front(struct list_head *list)
964 struct request *rq, *tmp, *first = NULL;
966 list_for_each_entry_safe_reverse(rq, tmp, list, queuelist) {
970 list_move(&rq->queuelist, list);
976 return first != NULL;
979 static int blk_mq_dispatch_wake(wait_queue_entry_t *wait, unsigned mode, int flags,
982 struct blk_mq_hw_ctx *hctx;
984 hctx = container_of(wait, struct blk_mq_hw_ctx, dispatch_wait);
986 list_del(&wait->entry);
987 clear_bit_unlock(BLK_MQ_S_TAG_WAITING, &hctx->state);
988 blk_mq_run_hw_queue(hctx, true);
992 static bool blk_mq_dispatch_wait_add(struct blk_mq_hw_ctx *hctx)
994 struct sbq_wait_state *ws;
997 * The TAG_WAITING bit serves as a lock protecting hctx->dispatch_wait.
998 * The thread which wins the race to grab this bit adds the hardware
999 * queue to the wait queue.
1001 if (test_bit(BLK_MQ_S_TAG_WAITING, &hctx->state) ||
1002 test_and_set_bit_lock(BLK_MQ_S_TAG_WAITING, &hctx->state))
1005 init_waitqueue_func_entry(&hctx->dispatch_wait, blk_mq_dispatch_wake);
1006 ws = bt_wait_ptr(&hctx->tags->bitmap_tags, hctx);
1009 * As soon as this returns, it's no longer safe to fiddle with
1010 * hctx->dispatch_wait, since a completion can wake up the wait queue
1011 * and unlock the bit.
1013 add_wait_queue(&ws->wait, &hctx->dispatch_wait);
1017 bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list)
1019 struct blk_mq_hw_ctx *hctx;
1023 if (list_empty(list))
1027 * Now process all the entries, sending them to the driver.
1029 errors = queued = 0;
1031 struct blk_mq_queue_data bd;
1034 rq = list_first_entry(list, struct request, queuelist);
1035 if (!blk_mq_get_driver_tag(rq, &hctx, false)) {
1036 if (!queued && reorder_tags_to_front(list))
1040 * The initial allocation attempt failed, so we need to
1041 * rerun the hardware queue when a tag is freed.
1043 if (!blk_mq_dispatch_wait_add(hctx))
1047 * It's possible that a tag was freed in the window
1048 * between the allocation failure and adding the
1049 * hardware queue to the wait queue.
1051 if (!blk_mq_get_driver_tag(rq, &hctx, false))
1055 list_del_init(&rq->queuelist);
1060 * Flag last if we have no more requests, or if we have more
1061 * but can't assign a driver tag to it.
1063 if (list_empty(list))
1066 struct request *nxt;
1068 nxt = list_first_entry(list, struct request, queuelist);
1069 bd.last = !blk_mq_get_driver_tag(nxt, NULL, false);
1072 ret = q->mq_ops->queue_rq(hctx, &bd);
1073 if (ret == BLK_STS_RESOURCE) {
1074 blk_mq_put_driver_tag_hctx(hctx, rq);
1075 list_add(&rq->queuelist, list);
1076 __blk_mq_requeue_request(rq);
1080 if (unlikely(ret != BLK_STS_OK)) {
1082 blk_mq_end_request(rq, BLK_STS_IOERR);
1087 } while (!list_empty(list));
1089 hctx->dispatched[queued_to_index(queued)]++;
1092 * Any items that need requeuing? Stuff them into hctx->dispatch,
1093 * that is where we will continue on next queue run.
1095 if (!list_empty(list)) {
1097 * If an I/O scheduler has been configured and we got a driver
1098 * tag for the next request already, free it again.
1100 rq = list_first_entry(list, struct request, queuelist);
1101 blk_mq_put_driver_tag(rq);
1103 spin_lock(&hctx->lock);
1104 list_splice_init(list, &hctx->dispatch);
1105 spin_unlock(&hctx->lock);
1108 * If SCHED_RESTART was set by the caller of this function and
1109 * it is no longer set that means that it was cleared by another
1110 * thread and hence that a queue rerun is needed.
1112 * If TAG_WAITING is set that means that an I/O scheduler has
1113 * been configured and another thread is waiting for a driver
1114 * tag. To guarantee fairness, do not rerun this hardware queue
1115 * but let the other thread grab the driver tag.
1117 * If no I/O scheduler has been configured it is possible that
1118 * the hardware queue got stopped and restarted before requests
1119 * were pushed back onto the dispatch list. Rerun the queue to
1120 * avoid starvation. Notes:
1121 * - blk_mq_run_hw_queue() checks whether or not a queue has
1122 * been stopped before rerunning a queue.
1123 * - Some but not all block drivers stop a queue before
1124 * returning BLK_STS_RESOURCE. Two exceptions are scsi-mq
1127 if (!blk_mq_sched_needs_restart(hctx) &&
1128 !test_bit(BLK_MQ_S_TAG_WAITING, &hctx->state))
1129 blk_mq_run_hw_queue(hctx, true);
1132 return (queued + errors) != 0;
1135 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
1140 * We should be running this queue from one of the CPUs that
1143 WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask) &&
1144 cpu_online(hctx->next_cpu));
1147 * We can't run the queue inline with ints disabled. Ensure that
1148 * we catch bad users of this early.
1150 WARN_ON_ONCE(in_interrupt());
1152 if (!(hctx->flags & BLK_MQ_F_BLOCKING)) {
1154 blk_mq_sched_dispatch_requests(hctx);
1159 srcu_idx = srcu_read_lock(hctx->queue_rq_srcu);
1160 blk_mq_sched_dispatch_requests(hctx);
1161 srcu_read_unlock(hctx->queue_rq_srcu, srcu_idx);
1166 * It'd be great if the workqueue API had a way to pass
1167 * in a mask and had some smarts for more clever placement.
1168 * For now we just round-robin here, switching for every
1169 * BLK_MQ_CPU_WORK_BATCH queued items.
1171 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
1173 if (hctx->queue->nr_hw_queues == 1)
1174 return WORK_CPU_UNBOUND;
1176 if (--hctx->next_cpu_batch <= 0) {
1179 next_cpu = cpumask_next(hctx->next_cpu, hctx->cpumask);
1180 if (next_cpu >= nr_cpu_ids)
1181 next_cpu = cpumask_first(hctx->cpumask);
1183 hctx->next_cpu = next_cpu;
1184 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
1187 return hctx->next_cpu;
1190 static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async,
1191 unsigned long msecs)
1193 if (WARN_ON_ONCE(!blk_mq_hw_queue_mapped(hctx)))
1196 if (unlikely(blk_mq_hctx_stopped(hctx)))
1199 if (!async && !(hctx->flags & BLK_MQ_F_BLOCKING)) {
1200 int cpu = get_cpu();
1201 if (cpumask_test_cpu(cpu, hctx->cpumask)) {
1202 __blk_mq_run_hw_queue(hctx);
1210 kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
1212 msecs_to_jiffies(msecs));
1215 void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
1217 __blk_mq_delay_run_hw_queue(hctx, true, msecs);
1219 EXPORT_SYMBOL(blk_mq_delay_run_hw_queue);
1221 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
1223 __blk_mq_delay_run_hw_queue(hctx, async, 0);
1225 EXPORT_SYMBOL(blk_mq_run_hw_queue);
1227 void blk_mq_run_hw_queues(struct request_queue *q, bool async)
1229 struct blk_mq_hw_ctx *hctx;
1232 queue_for_each_hw_ctx(q, hctx, i) {
1233 if (!blk_mq_hctx_has_pending(hctx) ||
1234 blk_mq_hctx_stopped(hctx))
1237 blk_mq_run_hw_queue(hctx, async);
1240 EXPORT_SYMBOL(blk_mq_run_hw_queues);
1243 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1244 * @q: request queue.
1246 * The caller is responsible for serializing this function against
1247 * blk_mq_{start,stop}_hw_queue().
1249 bool blk_mq_queue_stopped(struct request_queue *q)
1251 struct blk_mq_hw_ctx *hctx;
1254 queue_for_each_hw_ctx(q, hctx, i)
1255 if (blk_mq_hctx_stopped(hctx))
1260 EXPORT_SYMBOL(blk_mq_queue_stopped);
1263 * This function is often used for pausing .queue_rq() by driver when
1264 * there isn't enough resource or some conditions aren't satisfied, and
1265 * BLK_STS_RESOURCE is usually returned.
1267 * We do not guarantee that dispatch can be drained or blocked
1268 * after blk_mq_stop_hw_queue() returns. Please use
1269 * blk_mq_quiesce_queue() for that requirement.
1271 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
1273 cancel_delayed_work(&hctx->run_work);
1275 set_bit(BLK_MQ_S_STOPPED, &hctx->state);
1277 EXPORT_SYMBOL(blk_mq_stop_hw_queue);
1280 * This function is often used for pausing .queue_rq() by driver when
1281 * there isn't enough resource or some conditions aren't satisfied, and
1282 * BLK_STS_RESOURCE is usually returned.
1284 * We do not guarantee that dispatch can be drained or blocked
1285 * after blk_mq_stop_hw_queues() returns. Please use
1286 * blk_mq_quiesce_queue() for that requirement.
1288 void blk_mq_stop_hw_queues(struct request_queue *q)
1290 struct blk_mq_hw_ctx *hctx;
1293 queue_for_each_hw_ctx(q, hctx, i)
1294 blk_mq_stop_hw_queue(hctx);
1296 EXPORT_SYMBOL(blk_mq_stop_hw_queues);
1298 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
1300 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1302 blk_mq_run_hw_queue(hctx, false);
1304 EXPORT_SYMBOL(blk_mq_start_hw_queue);
1306 void blk_mq_start_hw_queues(struct request_queue *q)
1308 struct blk_mq_hw_ctx *hctx;
1311 queue_for_each_hw_ctx(q, hctx, i)
1312 blk_mq_start_hw_queue(hctx);
1314 EXPORT_SYMBOL(blk_mq_start_hw_queues);
1316 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
1318 if (!blk_mq_hctx_stopped(hctx))
1321 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1322 blk_mq_run_hw_queue(hctx, async);
1324 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue);
1326 void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async)
1328 struct blk_mq_hw_ctx *hctx;
1331 queue_for_each_hw_ctx(q, hctx, i)
1332 blk_mq_start_stopped_hw_queue(hctx, async);
1334 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);
1336 static void blk_mq_run_work_fn(struct work_struct *work)
1338 struct blk_mq_hw_ctx *hctx;
1340 hctx = container_of(work, struct blk_mq_hw_ctx, run_work.work);
1343 * If we are stopped, don't run the queue. The exception is if
1344 * BLK_MQ_S_START_ON_RUN is set. For that case, we auto-clear
1345 * the STOPPED bit and run it.
1347 if (test_bit(BLK_MQ_S_STOPPED, &hctx->state)) {
1348 if (!test_bit(BLK_MQ_S_START_ON_RUN, &hctx->state))
1351 clear_bit(BLK_MQ_S_START_ON_RUN, &hctx->state);
1352 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1355 __blk_mq_run_hw_queue(hctx);
1359 void blk_mq_delay_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
1361 if (WARN_ON_ONCE(!blk_mq_hw_queue_mapped(hctx)))
1365 * Stop the hw queue, then modify currently delayed work.
1366 * This should prevent us from running the queue prematurely.
1367 * Mark the queue as auto-clearing STOPPED when it runs.
1369 blk_mq_stop_hw_queue(hctx);
1370 set_bit(BLK_MQ_S_START_ON_RUN, &hctx->state);
1371 kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
1373 msecs_to_jiffies(msecs));
1375 EXPORT_SYMBOL(blk_mq_delay_queue);
1377 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx,
1381 struct blk_mq_ctx *ctx = rq->mq_ctx;
1383 lockdep_assert_held(&ctx->lock);
1385 trace_block_rq_insert(hctx->queue, rq);
1388 list_add(&rq->queuelist, &ctx->rq_list);
1390 list_add_tail(&rq->queuelist, &ctx->rq_list);
1393 void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
1396 struct blk_mq_ctx *ctx = rq->mq_ctx;
1398 lockdep_assert_held(&ctx->lock);
1400 __blk_mq_insert_req_list(hctx, rq, at_head);
1401 blk_mq_hctx_mark_pending(hctx, ctx);
1404 void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
1405 struct list_head *list)
1409 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1412 spin_lock(&ctx->lock);
1413 while (!list_empty(list)) {
1416 rq = list_first_entry(list, struct request, queuelist);
1417 BUG_ON(rq->mq_ctx != ctx);
1418 list_del_init(&rq->queuelist);
1419 __blk_mq_insert_req_list(hctx, rq, false);
1421 blk_mq_hctx_mark_pending(hctx, ctx);
1422 spin_unlock(&ctx->lock);
1425 static int plug_ctx_cmp(void *priv, struct list_head *a, struct list_head *b)
1427 struct request *rqa = container_of(a, struct request, queuelist);
1428 struct request *rqb = container_of(b, struct request, queuelist);
1430 return !(rqa->mq_ctx < rqb->mq_ctx ||
1431 (rqa->mq_ctx == rqb->mq_ctx &&
1432 blk_rq_pos(rqa) < blk_rq_pos(rqb)));
1435 void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
1437 struct blk_mq_ctx *this_ctx;
1438 struct request_queue *this_q;
1441 LIST_HEAD(ctx_list);
1444 list_splice_init(&plug->mq_list, &list);
1446 list_sort(NULL, &list, plug_ctx_cmp);
1452 while (!list_empty(&list)) {
1453 rq = list_entry_rq(list.next);
1454 list_del_init(&rq->queuelist);
1456 if (rq->mq_ctx != this_ctx) {
1458 trace_block_unplug(this_q, depth, from_schedule);
1459 blk_mq_sched_insert_requests(this_q, this_ctx,
1464 this_ctx = rq->mq_ctx;
1470 list_add_tail(&rq->queuelist, &ctx_list);
1474 * If 'this_ctx' is set, we know we have entries to complete
1475 * on 'ctx_list'. Do those.
1478 trace_block_unplug(this_q, depth, from_schedule);
1479 blk_mq_sched_insert_requests(this_q, this_ctx, &ctx_list,
1484 static void blk_mq_bio_to_request(struct request *rq, struct bio *bio)
1486 blk_init_request_from_bio(rq, bio);
1488 blk_account_io_start(rq, true);
1491 static inline bool hctx_allow_merges(struct blk_mq_hw_ctx *hctx)
1493 return (hctx->flags & BLK_MQ_F_SHOULD_MERGE) &&
1494 !blk_queue_nomerges(hctx->queue);
1497 static inline void blk_mq_queue_io(struct blk_mq_hw_ctx *hctx,
1498 struct blk_mq_ctx *ctx,
1501 spin_lock(&ctx->lock);
1502 __blk_mq_insert_request(hctx, rq, false);
1503 spin_unlock(&ctx->lock);
1506 static blk_qc_t request_to_qc_t(struct blk_mq_hw_ctx *hctx, struct request *rq)
1509 return blk_tag_to_qc_t(rq->tag, hctx->queue_num, false);
1511 return blk_tag_to_qc_t(rq->internal_tag, hctx->queue_num, true);
1514 static void __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
1516 blk_qc_t *cookie, bool may_sleep)
1518 struct request_queue *q = rq->q;
1519 struct blk_mq_queue_data bd = {
1523 blk_qc_t new_cookie;
1525 bool run_queue = true;
1527 /* RCU or SRCU read lock is needed before checking quiesced flag */
1528 if (blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q)) {
1536 if (!blk_mq_get_driver_tag(rq, NULL, false))
1539 new_cookie = request_to_qc_t(hctx, rq);
1542 * For OK queue, we are done. For error, kill it. Any other
1543 * error (busy), just add it to our list as we previously
1546 ret = q->mq_ops->queue_rq(hctx, &bd);
1549 *cookie = new_cookie;
1551 case BLK_STS_RESOURCE:
1552 __blk_mq_requeue_request(rq);
1555 *cookie = BLK_QC_T_NONE;
1556 blk_mq_end_request(rq, ret);
1561 blk_mq_sched_insert_request(rq, false, run_queue, false, may_sleep);
1564 static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
1565 struct request *rq, blk_qc_t *cookie)
1567 if (!(hctx->flags & BLK_MQ_F_BLOCKING)) {
1569 __blk_mq_try_issue_directly(hctx, rq, cookie, false);
1572 unsigned int srcu_idx;
1576 srcu_idx = srcu_read_lock(hctx->queue_rq_srcu);
1577 __blk_mq_try_issue_directly(hctx, rq, cookie, true);
1578 srcu_read_unlock(hctx->queue_rq_srcu, srcu_idx);
1582 static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
1584 const int is_sync = op_is_sync(bio->bi_opf);
1585 const int is_flush_fua = op_is_flush(bio->bi_opf);
1586 struct blk_mq_alloc_data data = { .flags = 0 };
1588 unsigned int request_count = 0;
1589 struct blk_plug *plug;
1590 struct request *same_queue_rq = NULL;
1592 unsigned int wb_acct;
1594 blk_queue_bounce(q, &bio);
1596 blk_queue_split(q, &bio);
1598 if (!bio_integrity_prep(bio))
1599 return BLK_QC_T_NONE;
1601 if (!is_flush_fua && !blk_queue_nomerges(q) &&
1602 blk_attempt_plug_merge(q, bio, &request_count, &same_queue_rq))
1603 return BLK_QC_T_NONE;
1605 if (blk_mq_sched_bio_merge(q, bio))
1606 return BLK_QC_T_NONE;
1608 wb_acct = wbt_wait(q->rq_wb, bio, NULL);
1610 trace_block_getrq(q, bio, bio->bi_opf);
1612 rq = blk_mq_get_request(q, bio, bio->bi_opf, &data);
1613 if (unlikely(!rq)) {
1614 __wbt_done(q->rq_wb, wb_acct);
1615 if (bio->bi_opf & REQ_NOWAIT)
1616 bio_wouldblock_error(bio);
1617 return BLK_QC_T_NONE;
1620 wbt_track(&rq->issue_stat, wb_acct);
1622 cookie = request_to_qc_t(data.hctx, rq);
1624 plug = current->plug;
1625 if (unlikely(is_flush_fua)) {
1626 blk_mq_put_ctx(data.ctx);
1627 blk_mq_bio_to_request(rq, bio);
1629 blk_mq_sched_insert_request(rq, false, true, true,
1632 blk_insert_flush(rq);
1633 blk_mq_run_hw_queue(data.hctx, true);
1635 } else if (plug && q->nr_hw_queues == 1) {
1636 struct request *last = NULL;
1638 blk_mq_put_ctx(data.ctx);
1639 blk_mq_bio_to_request(rq, bio);
1642 * @request_count may become stale because of schedule
1643 * out, so check the list again.
1645 if (list_empty(&plug->mq_list))
1647 else if (blk_queue_nomerges(q))
1648 request_count = blk_plug_queued_count(q);
1651 trace_block_plug(q);
1653 last = list_entry_rq(plug->mq_list.prev);
1655 if (request_count >= BLK_MAX_REQUEST_COUNT || (last &&
1656 blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
1657 blk_flush_plug_list(plug, false);
1658 trace_block_plug(q);
1661 list_add_tail(&rq->queuelist, &plug->mq_list);
1662 } else if (plug && !blk_queue_nomerges(q)) {
1663 blk_mq_bio_to_request(rq, bio);
1666 * We do limited plugging. If the bio can be merged, do that.
1667 * Otherwise the existing request in the plug list will be
1668 * issued. So the plug list will have one request at most
1669 * The plug list might get flushed before this. If that happens,
1670 * the plug list is empty, and same_queue_rq is invalid.
1672 if (list_empty(&plug->mq_list))
1673 same_queue_rq = NULL;
1675 list_del_init(&same_queue_rq->queuelist);
1676 list_add_tail(&rq->queuelist, &plug->mq_list);
1678 blk_mq_put_ctx(data.ctx);
1680 if (same_queue_rq) {
1681 data.hctx = blk_mq_map_queue(q,
1682 same_queue_rq->mq_ctx->cpu);
1683 blk_mq_try_issue_directly(data.hctx, same_queue_rq,
1686 } else if (q->nr_hw_queues > 1 && is_sync) {
1687 blk_mq_put_ctx(data.ctx);
1688 blk_mq_bio_to_request(rq, bio);
1689 blk_mq_try_issue_directly(data.hctx, rq, &cookie);
1690 } else if (q->elevator) {
1691 blk_mq_put_ctx(data.ctx);
1692 blk_mq_bio_to_request(rq, bio);
1693 blk_mq_sched_insert_request(rq, false, true, true, true);
1695 blk_mq_put_ctx(data.ctx);
1696 blk_mq_bio_to_request(rq, bio);
1697 blk_mq_queue_io(data.hctx, data.ctx, rq);
1698 blk_mq_run_hw_queue(data.hctx, true);
1704 void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
1705 unsigned int hctx_idx)
1709 if (tags->rqs && set->ops->exit_request) {
1712 for (i = 0; i < tags->nr_tags; i++) {
1713 struct request *rq = tags->static_rqs[i];
1717 set->ops->exit_request(set, rq, hctx_idx);
1718 tags->static_rqs[i] = NULL;
1722 while (!list_empty(&tags->page_list)) {
1723 page = list_first_entry(&tags->page_list, struct page, lru);
1724 list_del_init(&page->lru);
1726 * Remove kmemleak object previously allocated in
1727 * blk_mq_init_rq_map().
1729 kmemleak_free(page_address(page));
1730 __free_pages(page, page->private);
1734 void blk_mq_free_rq_map(struct blk_mq_tags *tags)
1738 kfree(tags->static_rqs);
1739 tags->static_rqs = NULL;
1741 blk_mq_free_tags(tags);
1744 struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set,
1745 unsigned int hctx_idx,
1746 unsigned int nr_tags,
1747 unsigned int reserved_tags)
1749 struct blk_mq_tags *tags;
1752 node = blk_mq_hw_queue_to_node(set->mq_map, hctx_idx);
1753 if (node == NUMA_NO_NODE)
1754 node = set->numa_node;
1756 tags = blk_mq_init_tags(nr_tags, reserved_tags, node,
1757 BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags));
1761 tags->rqs = kzalloc_node(nr_tags * sizeof(struct request *),
1762 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
1765 blk_mq_free_tags(tags);
1769 tags->static_rqs = kzalloc_node(nr_tags * sizeof(struct request *),
1770 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
1772 if (!tags->static_rqs) {
1774 blk_mq_free_tags(tags);
1781 static size_t order_to_size(unsigned int order)
1783 return (size_t)PAGE_SIZE << order;
1786 int blk_mq_alloc_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
1787 unsigned int hctx_idx, unsigned int depth)
1789 unsigned int i, j, entries_per_page, max_order = 4;
1790 size_t rq_size, left;
1793 node = blk_mq_hw_queue_to_node(set->mq_map, hctx_idx);
1794 if (node == NUMA_NO_NODE)
1795 node = set->numa_node;
1797 INIT_LIST_HEAD(&tags->page_list);
1800 * rq_size is the size of the request plus driver payload, rounded
1801 * to the cacheline size
1803 rq_size = round_up(sizeof(struct request) + set->cmd_size,
1805 left = rq_size * depth;
1807 for (i = 0; i < depth; ) {
1808 int this_order = max_order;
1813 while (this_order && left < order_to_size(this_order - 1))
1817 page = alloc_pages_node(node,
1818 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY | __GFP_ZERO,
1824 if (order_to_size(this_order) < rq_size)
1831 page->private = this_order;
1832 list_add_tail(&page->lru, &tags->page_list);
1834 p = page_address(page);
1836 * Allow kmemleak to scan these pages as they contain pointers
1837 * to additional allocations like via ops->init_request().
1839 kmemleak_alloc(p, order_to_size(this_order), 1, GFP_NOIO);
1840 entries_per_page = order_to_size(this_order) / rq_size;
1841 to_do = min(entries_per_page, depth - i);
1842 left -= to_do * rq_size;
1843 for (j = 0; j < to_do; j++) {
1844 struct request *rq = p;
1846 tags->static_rqs[i] = rq;
1847 if (set->ops->init_request) {
1848 if (set->ops->init_request(set, rq, hctx_idx,
1850 tags->static_rqs[i] = NULL;
1862 blk_mq_free_rqs(set, tags, hctx_idx);
1867 * 'cpu' is going away. splice any existing rq_list entries from this
1868 * software queue to the hw queue dispatch list, and ensure that it
1871 static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node)
1873 struct blk_mq_hw_ctx *hctx;
1874 struct blk_mq_ctx *ctx;
1877 hctx = hlist_entry_safe(node, struct blk_mq_hw_ctx, cpuhp_dead);
1878 ctx = __blk_mq_get_ctx(hctx->queue, cpu);
1880 spin_lock(&ctx->lock);
1881 if (!list_empty(&ctx->rq_list)) {
1882 list_splice_init(&ctx->rq_list, &tmp);
1883 blk_mq_hctx_clear_pending(hctx, ctx);
1885 spin_unlock(&ctx->lock);
1887 if (list_empty(&tmp))
1890 spin_lock(&hctx->lock);
1891 list_splice_tail_init(&tmp, &hctx->dispatch);
1892 spin_unlock(&hctx->lock);
1894 blk_mq_run_hw_queue(hctx, true);
1898 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx *hctx)
1900 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD,
1904 /* hctx->ctxs will be freed in queue's release handler */
1905 static void blk_mq_exit_hctx(struct request_queue *q,
1906 struct blk_mq_tag_set *set,
1907 struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
1909 blk_mq_debugfs_unregister_hctx(hctx);
1911 blk_mq_tag_idle(hctx);
1913 if (set->ops->exit_request)
1914 set->ops->exit_request(set, hctx->fq->flush_rq, hctx_idx);
1916 blk_mq_sched_exit_hctx(q, hctx, hctx_idx);
1918 if (set->ops->exit_hctx)
1919 set->ops->exit_hctx(hctx, hctx_idx);
1921 if (hctx->flags & BLK_MQ_F_BLOCKING)
1922 cleanup_srcu_struct(hctx->queue_rq_srcu);
1924 blk_mq_remove_cpuhp(hctx);
1925 blk_free_flush_queue(hctx->fq);
1926 sbitmap_free(&hctx->ctx_map);
1929 static void blk_mq_exit_hw_queues(struct request_queue *q,
1930 struct blk_mq_tag_set *set, int nr_queue)
1932 struct blk_mq_hw_ctx *hctx;
1935 queue_for_each_hw_ctx(q, hctx, i) {
1938 blk_mq_exit_hctx(q, set, hctx, i);
1942 static int blk_mq_init_hctx(struct request_queue *q,
1943 struct blk_mq_tag_set *set,
1944 struct blk_mq_hw_ctx *hctx, unsigned hctx_idx)
1948 node = hctx->numa_node;
1949 if (node == NUMA_NO_NODE)
1950 node = hctx->numa_node = set->numa_node;
1952 INIT_DELAYED_WORK(&hctx->run_work, blk_mq_run_work_fn);
1953 spin_lock_init(&hctx->lock);
1954 INIT_LIST_HEAD(&hctx->dispatch);
1956 hctx->flags = set->flags & ~BLK_MQ_F_TAG_SHARED;
1958 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD, &hctx->cpuhp_dead);
1960 hctx->tags = set->tags[hctx_idx];
1963 * Allocate space for all possible cpus to avoid allocation at
1966 hctx->ctxs = kmalloc_node(nr_cpu_ids * sizeof(void *),
1969 goto unregister_cpu_notifier;
1971 if (sbitmap_init_node(&hctx->ctx_map, nr_cpu_ids, ilog2(8), GFP_KERNEL,
1977 if (set->ops->init_hctx &&
1978 set->ops->init_hctx(hctx, set->driver_data, hctx_idx))
1981 if (blk_mq_sched_init_hctx(q, hctx, hctx_idx))
1984 hctx->fq = blk_alloc_flush_queue(q, hctx->numa_node, set->cmd_size);
1986 goto sched_exit_hctx;
1988 if (set->ops->init_request &&
1989 set->ops->init_request(set, hctx->fq->flush_rq, hctx_idx,
1993 if (hctx->flags & BLK_MQ_F_BLOCKING)
1994 init_srcu_struct(hctx->queue_rq_srcu);
1996 blk_mq_debugfs_register_hctx(q, hctx);
2003 blk_mq_sched_exit_hctx(q, hctx, hctx_idx);
2005 if (set->ops->exit_hctx)
2006 set->ops->exit_hctx(hctx, hctx_idx);
2008 sbitmap_free(&hctx->ctx_map);
2011 unregister_cpu_notifier:
2012 blk_mq_remove_cpuhp(hctx);
2016 static void blk_mq_init_cpu_queues(struct request_queue *q,
2017 unsigned int nr_hw_queues)
2021 for_each_possible_cpu(i) {
2022 struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
2023 struct blk_mq_hw_ctx *hctx;
2026 spin_lock_init(&__ctx->lock);
2027 INIT_LIST_HEAD(&__ctx->rq_list);
2030 /* If the cpu isn't present, the cpu is mapped to first hctx */
2031 if (!cpu_present(i))
2034 hctx = blk_mq_map_queue(q, i);
2037 * Set local node, IFF we have more than one hw queue. If
2038 * not, we remain on the home node of the device
2040 if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE)
2041 hctx->numa_node = local_memory_node(cpu_to_node(i));
2045 static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set *set, int hctx_idx)
2049 set->tags[hctx_idx] = blk_mq_alloc_rq_map(set, hctx_idx,
2050 set->queue_depth, set->reserved_tags);
2051 if (!set->tags[hctx_idx])
2054 ret = blk_mq_alloc_rqs(set, set->tags[hctx_idx], hctx_idx,
2059 blk_mq_free_rq_map(set->tags[hctx_idx]);
2060 set->tags[hctx_idx] = NULL;
2064 static void blk_mq_free_map_and_requests(struct blk_mq_tag_set *set,
2065 unsigned int hctx_idx)
2067 if (set->tags[hctx_idx]) {
2068 blk_mq_free_rqs(set, set->tags[hctx_idx], hctx_idx);
2069 blk_mq_free_rq_map(set->tags[hctx_idx]);
2070 set->tags[hctx_idx] = NULL;
2074 static void blk_mq_map_swqueue(struct request_queue *q)
2076 unsigned int i, hctx_idx;
2077 struct blk_mq_hw_ctx *hctx;
2078 struct blk_mq_ctx *ctx;
2079 struct blk_mq_tag_set *set = q->tag_set;
2082 * Avoid others reading imcomplete hctx->cpumask through sysfs
2084 mutex_lock(&q->sysfs_lock);
2086 queue_for_each_hw_ctx(q, hctx, i) {
2087 cpumask_clear(hctx->cpumask);
2092 * Map software to hardware queues.
2094 * If the cpu isn't present, the cpu is mapped to first hctx.
2096 for_each_present_cpu(i) {
2097 hctx_idx = q->mq_map[i];
2098 /* unmapped hw queue can be remapped after CPU topo changed */
2099 if (!set->tags[hctx_idx] &&
2100 !__blk_mq_alloc_rq_map(set, hctx_idx)) {
2102 * If tags initialization fail for some hctx,
2103 * that hctx won't be brought online. In this
2104 * case, remap the current ctx to hctx[0] which
2105 * is guaranteed to always have tags allocated
2110 ctx = per_cpu_ptr(q->queue_ctx, i);
2111 hctx = blk_mq_map_queue(q, i);
2113 cpumask_set_cpu(i, hctx->cpumask);
2114 ctx->index_hw = hctx->nr_ctx;
2115 hctx->ctxs[hctx->nr_ctx++] = ctx;
2118 mutex_unlock(&q->sysfs_lock);
2120 queue_for_each_hw_ctx(q, hctx, i) {
2122 * If no software queues are mapped to this hardware queue,
2123 * disable it and free the request entries.
2125 if (!hctx->nr_ctx) {
2126 /* Never unmap queue 0. We need it as a
2127 * fallback in case of a new remap fails
2130 if (i && set->tags[i])
2131 blk_mq_free_map_and_requests(set, i);
2137 hctx->tags = set->tags[i];
2138 WARN_ON(!hctx->tags);
2141 * Set the map size to the number of mapped software queues.
2142 * This is more accurate and more efficient than looping
2143 * over all possibly mapped software queues.
2145 sbitmap_resize(&hctx->ctx_map, hctx->nr_ctx);
2148 * Initialize batch roundrobin counts
2150 hctx->next_cpu = cpumask_first(hctx->cpumask);
2151 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
2156 * Caller needs to ensure that we're either frozen/quiesced, or that
2157 * the queue isn't live yet.
2159 static void queue_set_hctx_shared(struct request_queue *q, bool shared)
2161 struct blk_mq_hw_ctx *hctx;
2164 queue_for_each_hw_ctx(q, hctx, i) {
2166 if (test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state))
2167 atomic_inc(&q->shared_hctx_restart);
2168 hctx->flags |= BLK_MQ_F_TAG_SHARED;
2170 if (test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state))
2171 atomic_dec(&q->shared_hctx_restart);
2172 hctx->flags &= ~BLK_MQ_F_TAG_SHARED;
2177 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set,
2180 struct request_queue *q;
2182 lockdep_assert_held(&set->tag_list_lock);
2184 list_for_each_entry(q, &set->tag_list, tag_set_list) {
2185 blk_mq_freeze_queue(q);
2186 queue_set_hctx_shared(q, shared);
2187 blk_mq_unfreeze_queue(q);
2191 static void blk_mq_del_queue_tag_set(struct request_queue *q)
2193 struct blk_mq_tag_set *set = q->tag_set;
2195 mutex_lock(&set->tag_list_lock);
2196 list_del_rcu(&q->tag_set_list);
2197 INIT_LIST_HEAD(&q->tag_set_list);
2198 if (list_is_singular(&set->tag_list)) {
2199 /* just transitioned to unshared */
2200 set->flags &= ~BLK_MQ_F_TAG_SHARED;
2201 /* update existing queue */
2202 blk_mq_update_tag_set_depth(set, false);
2204 mutex_unlock(&set->tag_list_lock);
2209 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
2210 struct request_queue *q)
2214 mutex_lock(&set->tag_list_lock);
2216 /* Check to see if we're transitioning to shared (from 1 to 2 queues). */
2217 if (!list_empty(&set->tag_list) && !(set->flags & BLK_MQ_F_TAG_SHARED)) {
2218 set->flags |= BLK_MQ_F_TAG_SHARED;
2219 /* update existing queue */
2220 blk_mq_update_tag_set_depth(set, true);
2222 if (set->flags & BLK_MQ_F_TAG_SHARED)
2223 queue_set_hctx_shared(q, true);
2224 list_add_tail_rcu(&q->tag_set_list, &set->tag_list);
2226 mutex_unlock(&set->tag_list_lock);
2230 * It is the actual release handler for mq, but we do it from
2231 * request queue's release handler for avoiding use-after-free
2232 * and headache because q->mq_kobj shouldn't have been introduced,
2233 * but we can't group ctx/kctx kobj without it.
2235 void blk_mq_release(struct request_queue *q)
2237 struct blk_mq_hw_ctx *hctx;
2240 /* hctx kobj stays in hctx */
2241 queue_for_each_hw_ctx(q, hctx, i) {
2244 kobject_put(&hctx->kobj);
2249 kfree(q->queue_hw_ctx);
2252 * release .mq_kobj and sw queue's kobject now because
2253 * both share lifetime with request queue.
2255 blk_mq_sysfs_deinit(q);
2257 free_percpu(q->queue_ctx);
2260 struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
2262 struct request_queue *uninit_q, *q;
2264 uninit_q = blk_alloc_queue_node(GFP_KERNEL, set->numa_node);
2266 return ERR_PTR(-ENOMEM);
2268 q = blk_mq_init_allocated_queue(set, uninit_q);
2270 blk_cleanup_queue(uninit_q);
2274 EXPORT_SYMBOL(blk_mq_init_queue);
2276 static int blk_mq_hw_ctx_size(struct blk_mq_tag_set *tag_set)
2278 int hw_ctx_size = sizeof(struct blk_mq_hw_ctx);
2280 BUILD_BUG_ON(ALIGN(offsetof(struct blk_mq_hw_ctx, queue_rq_srcu),
2281 __alignof__(struct blk_mq_hw_ctx)) !=
2282 sizeof(struct blk_mq_hw_ctx));
2284 if (tag_set->flags & BLK_MQ_F_BLOCKING)
2285 hw_ctx_size += sizeof(struct srcu_struct);
2290 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
2291 struct request_queue *q)
2294 struct blk_mq_hw_ctx **hctxs = q->queue_hw_ctx;
2296 blk_mq_sysfs_unregister(q);
2297 for (i = 0; i < set->nr_hw_queues; i++) {
2303 node = blk_mq_hw_queue_to_node(q->mq_map, i);
2304 hctxs[i] = kzalloc_node(blk_mq_hw_ctx_size(set),
2309 if (!zalloc_cpumask_var_node(&hctxs[i]->cpumask, GFP_KERNEL,
2316 atomic_set(&hctxs[i]->nr_active, 0);
2317 hctxs[i]->numa_node = node;
2318 hctxs[i]->queue_num = i;
2320 if (blk_mq_init_hctx(q, set, hctxs[i], i)) {
2321 free_cpumask_var(hctxs[i]->cpumask);
2326 blk_mq_hctx_kobj_init(hctxs[i]);
2328 for (j = i; j < q->nr_hw_queues; j++) {
2329 struct blk_mq_hw_ctx *hctx = hctxs[j];
2333 blk_mq_free_map_and_requests(set, j);
2334 blk_mq_exit_hctx(q, set, hctx, j);
2335 kobject_put(&hctx->kobj);
2340 q->nr_hw_queues = i;
2341 blk_mq_sysfs_register(q);
2344 struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
2345 struct request_queue *q)
2347 /* mark the queue as mq asap */
2348 q->mq_ops = set->ops;
2350 q->poll_cb = blk_stat_alloc_callback(blk_mq_poll_stats_fn,
2351 blk_mq_poll_stats_bkt,
2352 BLK_MQ_POLL_STATS_BKTS, q);
2356 q->queue_ctx = alloc_percpu(struct blk_mq_ctx);
2360 /* init q->mq_kobj and sw queues' kobjects */
2361 blk_mq_sysfs_init(q);
2363 q->queue_hw_ctx = kzalloc_node(nr_cpu_ids * sizeof(*(q->queue_hw_ctx)),
2364 GFP_KERNEL, set->numa_node);
2365 if (!q->queue_hw_ctx)
2368 q->mq_map = set->mq_map;
2370 blk_mq_realloc_hw_ctxs(set, q);
2371 if (!q->nr_hw_queues)
2374 INIT_WORK(&q->timeout_work, blk_mq_timeout_work);
2375 blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);
2377 q->nr_queues = nr_cpu_ids;
2379 q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
2381 if (!(set->flags & BLK_MQ_F_SG_MERGE))
2382 q->queue_flags |= 1 << QUEUE_FLAG_NO_SG_MERGE;
2384 q->sg_reserved_size = INT_MAX;
2386 INIT_DELAYED_WORK(&q->requeue_work, blk_mq_requeue_work);
2387 INIT_LIST_HEAD(&q->requeue_list);
2388 spin_lock_init(&q->requeue_lock);
2390 blk_queue_make_request(q, blk_mq_make_request);
2393 * Do this after blk_queue_make_request() overrides it...
2395 q->nr_requests = set->queue_depth;
2398 * Default to classic polling
2402 if (set->ops->complete)
2403 blk_queue_softirq_done(q, set->ops->complete);
2405 blk_mq_init_cpu_queues(q, set->nr_hw_queues);
2406 blk_mq_add_queue_tag_set(set, q);
2407 blk_mq_map_swqueue(q);
2409 if (!(set->flags & BLK_MQ_F_NO_SCHED)) {
2412 ret = blk_mq_sched_init(q);
2414 return ERR_PTR(ret);
2420 kfree(q->queue_hw_ctx);
2422 free_percpu(q->queue_ctx);
2425 return ERR_PTR(-ENOMEM);
2427 EXPORT_SYMBOL(blk_mq_init_allocated_queue);
2429 void blk_mq_free_queue(struct request_queue *q)
2431 struct blk_mq_tag_set *set = q->tag_set;
2433 blk_mq_del_queue_tag_set(q);
2434 blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
2437 /* Basically redo blk_mq_init_queue with queue frozen */
2438 static void blk_mq_queue_reinit(struct request_queue *q)
2440 WARN_ON_ONCE(!atomic_read(&q->mq_freeze_depth));
2442 blk_mq_debugfs_unregister_hctxs(q);
2443 blk_mq_sysfs_unregister(q);
2446 * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
2447 * we should change hctx numa_node according to new topology (this
2448 * involves free and re-allocate memory, worthy doing?)
2451 blk_mq_map_swqueue(q);
2453 blk_mq_sysfs_register(q);
2454 blk_mq_debugfs_register_hctxs(q);
2457 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2461 for (i = 0; i < set->nr_hw_queues; i++)
2462 if (!__blk_mq_alloc_rq_map(set, i))
2469 blk_mq_free_rq_map(set->tags[i]);
2475 * Allocate the request maps associated with this tag_set. Note that this
2476 * may reduce the depth asked for, if memory is tight. set->queue_depth
2477 * will be updated to reflect the allocated depth.
2479 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2484 depth = set->queue_depth;
2486 err = __blk_mq_alloc_rq_maps(set);
2490 set->queue_depth >>= 1;
2491 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN) {
2495 } while (set->queue_depth);
2497 if (!set->queue_depth || err) {
2498 pr_err("blk-mq: failed to allocate request map\n");
2502 if (depth != set->queue_depth)
2503 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2504 depth, set->queue_depth);
2509 static int blk_mq_update_queue_map(struct blk_mq_tag_set *set)
2511 if (set->ops->map_queues)
2512 return set->ops->map_queues(set);
2514 return blk_mq_map_queues(set);
2518 * Alloc a tag set to be associated with one or more request queues.
2519 * May fail with EINVAL for various error conditions. May adjust the
2520 * requested depth down, if if it too large. In that case, the set
2521 * value will be stored in set->queue_depth.
2523 int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
2527 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH > 1 << BLK_MQ_UNIQUE_TAG_BITS);
2529 if (!set->nr_hw_queues)
2531 if (!set->queue_depth)
2533 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN)
2536 if (!set->ops->queue_rq)
2539 if (set->queue_depth > BLK_MQ_MAX_DEPTH) {
2540 pr_info("blk-mq: reduced tag depth to %u\n",
2542 set->queue_depth = BLK_MQ_MAX_DEPTH;
2546 * If a crashdump is active, then we are potentially in a very
2547 * memory constrained environment. Limit us to 1 queue and
2548 * 64 tags to prevent using too much memory.
2550 if (is_kdump_kernel()) {
2551 set->nr_hw_queues = 1;
2552 set->queue_depth = min(64U, set->queue_depth);
2555 * There is no use for more h/w queues than cpus.
2557 if (set->nr_hw_queues > nr_cpu_ids)
2558 set->nr_hw_queues = nr_cpu_ids;
2560 set->tags = kzalloc_node(nr_cpu_ids * sizeof(struct blk_mq_tags *),
2561 GFP_KERNEL, set->numa_node);
2566 set->mq_map = kzalloc_node(sizeof(*set->mq_map) * nr_cpu_ids,
2567 GFP_KERNEL, set->numa_node);
2571 ret = blk_mq_update_queue_map(set);
2573 goto out_free_mq_map;
2575 ret = blk_mq_alloc_rq_maps(set);
2577 goto out_free_mq_map;
2579 mutex_init(&set->tag_list_lock);
2580 INIT_LIST_HEAD(&set->tag_list);
2592 EXPORT_SYMBOL(blk_mq_alloc_tag_set);
2594 void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
2598 for (i = 0; i < nr_cpu_ids; i++)
2599 blk_mq_free_map_and_requests(set, i);
2607 EXPORT_SYMBOL(blk_mq_free_tag_set);
2609 int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
2611 struct blk_mq_tag_set *set = q->tag_set;
2612 struct blk_mq_hw_ctx *hctx;
2618 blk_mq_freeze_queue(q);
2621 queue_for_each_hw_ctx(q, hctx, i) {
2625 * If we're using an MQ scheduler, just update the scheduler
2626 * queue depth. This is similar to what the old code would do.
2628 if (!hctx->sched_tags) {
2629 ret = blk_mq_tag_update_depth(hctx, &hctx->tags,
2630 min(nr, set->queue_depth),
2633 ret = blk_mq_tag_update_depth(hctx, &hctx->sched_tags,
2641 q->nr_requests = nr;
2643 blk_mq_unfreeze_queue(q);
2648 static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set,
2651 struct request_queue *q;
2653 lockdep_assert_held(&set->tag_list_lock);
2655 if (nr_hw_queues > nr_cpu_ids)
2656 nr_hw_queues = nr_cpu_ids;
2657 if (nr_hw_queues < 1 || nr_hw_queues == set->nr_hw_queues)
2660 list_for_each_entry(q, &set->tag_list, tag_set_list)
2661 blk_mq_freeze_queue(q);
2663 set->nr_hw_queues = nr_hw_queues;
2664 blk_mq_update_queue_map(set);
2665 list_for_each_entry(q, &set->tag_list, tag_set_list) {
2666 blk_mq_realloc_hw_ctxs(set, q);
2667 blk_mq_queue_reinit(q);
2670 list_for_each_entry(q, &set->tag_list, tag_set_list)
2671 blk_mq_unfreeze_queue(q);
2674 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
2676 mutex_lock(&set->tag_list_lock);
2677 __blk_mq_update_nr_hw_queues(set, nr_hw_queues);
2678 mutex_unlock(&set->tag_list_lock);
2680 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues);
2682 /* Enable polling stats and return whether they were already enabled. */
2683 static bool blk_poll_stats_enable(struct request_queue *q)
2685 if (test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
2686 test_and_set_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags))
2688 blk_stat_add_callback(q, q->poll_cb);
2692 static void blk_mq_poll_stats_start(struct request_queue *q)
2695 * We don't arm the callback if polling stats are not enabled or the
2696 * callback is already active.
2698 if (!test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
2699 blk_stat_is_active(q->poll_cb))
2702 blk_stat_activate_msecs(q->poll_cb, 100);
2705 static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb)
2707 struct request_queue *q = cb->data;
2710 for (bucket = 0; bucket < BLK_MQ_POLL_STATS_BKTS; bucket++) {
2711 if (cb->stat[bucket].nr_samples)
2712 q->poll_stat[bucket] = cb->stat[bucket];
2716 static unsigned long blk_mq_poll_nsecs(struct request_queue *q,
2717 struct blk_mq_hw_ctx *hctx,
2720 unsigned long ret = 0;
2724 * If stats collection isn't on, don't sleep but turn it on for
2727 if (!blk_poll_stats_enable(q))
2731 * As an optimistic guess, use half of the mean service time
2732 * for this type of request. We can (and should) make this smarter.
2733 * For instance, if the completion latencies are tight, we can
2734 * get closer than just half the mean. This is especially
2735 * important on devices where the completion latencies are longer
2736 * than ~10 usec. We do use the stats for the relevant IO size
2737 * if available which does lead to better estimates.
2739 bucket = blk_mq_poll_stats_bkt(rq);
2743 if (q->poll_stat[bucket].nr_samples)
2744 ret = (q->poll_stat[bucket].mean + 1) / 2;
2749 static bool blk_mq_poll_hybrid_sleep(struct request_queue *q,
2750 struct blk_mq_hw_ctx *hctx,
2753 struct hrtimer_sleeper hs;
2754 enum hrtimer_mode mode;
2758 if (test_bit(REQ_ATOM_POLL_SLEPT, &rq->atomic_flags))
2764 * -1: don't ever hybrid sleep
2765 * 0: use half of prev avg
2766 * >0: use this specific value
2768 if (q->poll_nsec == -1)
2770 else if (q->poll_nsec > 0)
2771 nsecs = q->poll_nsec;
2773 nsecs = blk_mq_poll_nsecs(q, hctx, rq);
2778 set_bit(REQ_ATOM_POLL_SLEPT, &rq->atomic_flags);
2781 * This will be replaced with the stats tracking code, using
2782 * 'avg_completion_time / 2' as the pre-sleep target.
2786 mode = HRTIMER_MODE_REL;
2787 hrtimer_init_on_stack(&hs.timer, CLOCK_MONOTONIC, mode);
2788 hrtimer_set_expires(&hs.timer, kt);
2790 hrtimer_init_sleeper(&hs, current);
2792 if (test_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags))
2794 set_current_state(TASK_UNINTERRUPTIBLE);
2795 hrtimer_start_expires(&hs.timer, mode);
2798 hrtimer_cancel(&hs.timer);
2799 mode = HRTIMER_MODE_ABS;
2800 } while (hs.task && !signal_pending(current));
2802 __set_current_state(TASK_RUNNING);
2803 destroy_hrtimer_on_stack(&hs.timer);
2807 static bool __blk_mq_poll(struct blk_mq_hw_ctx *hctx, struct request *rq)
2809 struct request_queue *q = hctx->queue;
2813 * If we sleep, have the caller restart the poll loop to reset
2814 * the state. Like for the other success return cases, the
2815 * caller is responsible for checking if the IO completed. If
2816 * the IO isn't complete, we'll get called again and will go
2817 * straight to the busy poll loop.
2819 if (blk_mq_poll_hybrid_sleep(q, hctx, rq))
2822 hctx->poll_considered++;
2824 state = current->state;
2825 while (!need_resched()) {
2828 hctx->poll_invoked++;
2830 ret = q->mq_ops->poll(hctx, rq->tag);
2832 hctx->poll_success++;
2833 set_current_state(TASK_RUNNING);
2837 if (signal_pending_state(state, current))
2838 set_current_state(TASK_RUNNING);
2840 if (current->state == TASK_RUNNING)
2850 bool blk_mq_poll(struct request_queue *q, blk_qc_t cookie)
2852 struct blk_mq_hw_ctx *hctx;
2853 struct blk_plug *plug;
2856 if (!q->mq_ops || !q->mq_ops->poll || !blk_qc_t_valid(cookie) ||
2857 !test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
2860 plug = current->plug;
2862 blk_flush_plug_list(plug, false);
2864 hctx = q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)];
2865 if (!blk_qc_t_is_internal(cookie))
2866 rq = blk_mq_tag_to_rq(hctx->tags, blk_qc_t_to_tag(cookie));
2868 rq = blk_mq_tag_to_rq(hctx->sched_tags, blk_qc_t_to_tag(cookie));
2870 * With scheduling, if the request has completed, we'll
2871 * get a NULL return here, as we clear the sched tag when
2872 * that happens. The request still remains valid, like always,
2873 * so we should be safe with just the NULL check.
2879 return __blk_mq_poll(hctx, rq);
2881 EXPORT_SYMBOL_GPL(blk_mq_poll);
2883 static int __init blk_mq_init(void)
2885 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD, "block/mq:dead", NULL,
2886 blk_mq_hctx_notify_dead);
2889 subsys_initcall(blk_mq_init);