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 DEFINE_MUTEX(all_q_mutex
);
41 static LIST_HEAD(all_q_list
);
43 static void blk_mq_poll_stats_start(struct request_queue
*q
);
44 static void blk_mq_poll_stats_fn(struct blk_stat_callback
*cb
);
46 static int blk_mq_poll_stats_bkt(const struct request
*rq
)
48 int ddir
, bytes
, bucket
;
50 ddir
= rq_data_dir(rq
);
51 bytes
= blk_rq_bytes(rq
);
53 bucket
= ddir
+ 2*(ilog2(bytes
) - 9);
57 else if (bucket
>= BLK_MQ_POLL_STATS_BKTS
)
58 return ddir
+ BLK_MQ_POLL_STATS_BKTS
- 2;
64 * Check if any of the ctx's have pending work in this hardware queue
66 bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx
*hctx
)
68 return sbitmap_any_bit_set(&hctx
->ctx_map
) ||
69 !list_empty_careful(&hctx
->dispatch
) ||
70 blk_mq_sched_has_work(hctx
);
74 * Mark this ctx as having pending work in this hardware queue
76 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx
*hctx
,
77 struct blk_mq_ctx
*ctx
)
79 if (!sbitmap_test_bit(&hctx
->ctx_map
, ctx
->index_hw
))
80 sbitmap_set_bit(&hctx
->ctx_map
, ctx
->index_hw
);
83 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx
*hctx
,
84 struct blk_mq_ctx
*ctx
)
86 sbitmap_clear_bit(&hctx
->ctx_map
, ctx
->index_hw
);
89 void blk_freeze_queue_start(struct request_queue
*q
)
93 freeze_depth
= atomic_inc_return(&q
->mq_freeze_depth
);
94 if (freeze_depth
== 1) {
95 percpu_ref_kill(&q
->q_usage_counter
);
96 blk_mq_run_hw_queues(q
, false);
99 EXPORT_SYMBOL_GPL(blk_freeze_queue_start
);
101 void blk_mq_freeze_queue_wait(struct request_queue
*q
)
103 wait_event(q
->mq_freeze_wq
, percpu_ref_is_zero(&q
->q_usage_counter
));
105 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait
);
107 int blk_mq_freeze_queue_wait_timeout(struct request_queue
*q
,
108 unsigned long timeout
)
110 return wait_event_timeout(q
->mq_freeze_wq
,
111 percpu_ref_is_zero(&q
->q_usage_counter
),
114 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout
);
117 * Guarantee no request is in use, so we can change any data structure of
118 * the queue afterward.
120 void blk_freeze_queue(struct request_queue
*q
)
123 * In the !blk_mq case we are only calling this to kill the
124 * q_usage_counter, otherwise this increases the freeze depth
125 * and waits for it to return to zero. For this reason there is
126 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
127 * exported to drivers as the only user for unfreeze is blk_mq.
129 blk_freeze_queue_start(q
);
130 blk_mq_freeze_queue_wait(q
);
133 void blk_mq_freeze_queue(struct request_queue
*q
)
136 * ...just an alias to keep freeze and unfreeze actions balanced
137 * in the blk_mq_* namespace
141 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue
);
143 void blk_mq_unfreeze_queue(struct request_queue
*q
)
147 freeze_depth
= atomic_dec_return(&q
->mq_freeze_depth
);
148 WARN_ON_ONCE(freeze_depth
< 0);
150 percpu_ref_reinit(&q
->q_usage_counter
);
151 wake_up_all(&q
->mq_freeze_wq
);
154 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue
);
157 * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished
160 * Note: this function does not prevent that the struct request end_io()
161 * callback function is invoked. Once this function is returned, we make
162 * sure no dispatch can happen until the queue is unquiesced via
163 * blk_mq_unquiesce_queue().
165 void blk_mq_quiesce_queue(struct request_queue
*q
)
167 struct blk_mq_hw_ctx
*hctx
;
171 blk_mq_quiesce_queue_nowait(q
);
173 queue_for_each_hw_ctx(q
, hctx
, i
) {
174 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
175 synchronize_srcu(&hctx
->queue_rq_srcu
);
182 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue
);
185 * blk_mq_unquiesce_queue() - counterpart of blk_mq_quiesce_queue()
188 * This function recovers queue into the state before quiescing
189 * which is done by blk_mq_quiesce_queue.
191 void blk_mq_unquiesce_queue(struct request_queue
*q
)
193 spin_lock_irq(q
->queue_lock
);
194 queue_flag_clear(QUEUE_FLAG_QUIESCED
, q
);
195 spin_unlock_irq(q
->queue_lock
);
197 /* dispatch requests which are inserted during quiescing */
198 blk_mq_run_hw_queues(q
, true);
200 EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue
);
202 void blk_mq_wake_waiters(struct request_queue
*q
)
204 struct blk_mq_hw_ctx
*hctx
;
207 queue_for_each_hw_ctx(q
, hctx
, i
)
208 if (blk_mq_hw_queue_mapped(hctx
))
209 blk_mq_tag_wakeup_all(hctx
->tags
, true);
212 * If we are called because the queue has now been marked as
213 * dying, we need to ensure that processes currently waiting on
214 * the queue are notified as well.
216 wake_up_all(&q
->mq_freeze_wq
);
219 bool blk_mq_can_queue(struct blk_mq_hw_ctx
*hctx
)
221 return blk_mq_has_free_tags(hctx
->tags
);
223 EXPORT_SYMBOL(blk_mq_can_queue
);
225 static struct request
*blk_mq_rq_ctx_init(struct blk_mq_alloc_data
*data
,
226 unsigned int tag
, unsigned int op
)
228 struct blk_mq_tags
*tags
= blk_mq_tags_from_data(data
);
229 struct request
*rq
= tags
->static_rqs
[tag
];
231 if (data
->flags
& BLK_MQ_REQ_INTERNAL
) {
233 rq
->internal_tag
= tag
;
235 if (blk_mq_tag_busy(data
->hctx
)) {
236 rq
->rq_flags
= RQF_MQ_INFLIGHT
;
237 atomic_inc(&data
->hctx
->nr_active
);
240 rq
->internal_tag
= -1;
241 data
->hctx
->tags
->rqs
[rq
->tag
] = rq
;
244 INIT_LIST_HEAD(&rq
->queuelist
);
245 /* csd/requeue_work/fifo_time is initialized before use */
247 rq
->mq_ctx
= data
->ctx
;
249 if (blk_queue_io_stat(data
->q
))
250 rq
->rq_flags
|= RQF_IO_STAT
;
251 /* do not touch atomic flags, it needs atomic ops against the timer */
253 INIT_HLIST_NODE(&rq
->hash
);
254 RB_CLEAR_NODE(&rq
->rb_node
);
257 rq
->start_time
= jiffies
;
258 #ifdef CONFIG_BLK_CGROUP
260 set_start_time_ns(rq
);
261 rq
->io_start_time_ns
= 0;
263 rq
->nr_phys_segments
= 0;
264 #if defined(CONFIG_BLK_DEV_INTEGRITY)
265 rq
->nr_integrity_segments
= 0;
268 /* tag was already set */
271 INIT_LIST_HEAD(&rq
->timeout_list
);
275 rq
->end_io_data
= NULL
;
278 data
->ctx
->rq_dispatched
[op_is_sync(op
)]++;
282 static struct request
*blk_mq_get_request(struct request_queue
*q
,
283 struct bio
*bio
, unsigned int op
,
284 struct blk_mq_alloc_data
*data
)
286 struct elevator_queue
*e
= q
->elevator
;
290 blk_queue_enter_live(q
);
292 if (likely(!data
->ctx
))
293 data
->ctx
= blk_mq_get_ctx(q
);
294 if (likely(!data
->hctx
))
295 data
->hctx
= blk_mq_map_queue(q
, data
->ctx
->cpu
);
297 data
->flags
|= BLK_MQ_REQ_NOWAIT
;
300 data
->flags
|= BLK_MQ_REQ_INTERNAL
;
303 * Flush requests are special and go directly to the
306 if (!op_is_flush(op
) && e
->type
->ops
.mq
.limit_depth
)
307 e
->type
->ops
.mq
.limit_depth(op
, data
);
310 tag
= blk_mq_get_tag(data
);
311 if (tag
== BLK_MQ_TAG_FAIL
) {
316 rq
= blk_mq_rq_ctx_init(data
, tag
, op
);
317 if (!op_is_flush(op
)) {
319 if (e
&& e
->type
->ops
.mq
.prepare_request
) {
320 if (e
->type
->icq_cache
&& rq_ioc(bio
))
321 blk_mq_sched_assign_ioc(rq
, bio
);
323 e
->type
->ops
.mq
.prepare_request(rq
, bio
);
324 rq
->rq_flags
|= RQF_ELVPRIV
;
327 data
->hctx
->queued
++;
331 struct request
*blk_mq_alloc_request(struct request_queue
*q
, int rw
,
334 struct blk_mq_alloc_data alloc_data
= { .flags
= flags
};
338 ret
= blk_queue_enter(q
, flags
& BLK_MQ_REQ_NOWAIT
);
342 rq
= blk_mq_get_request(q
, NULL
, rw
, &alloc_data
);
344 blk_mq_put_ctx(alloc_data
.ctx
);
348 return ERR_PTR(-EWOULDBLOCK
);
351 rq
->__sector
= (sector_t
) -1;
352 rq
->bio
= rq
->biotail
= NULL
;
355 EXPORT_SYMBOL(blk_mq_alloc_request
);
357 struct request
*blk_mq_alloc_request_hctx(struct request_queue
*q
, int rw
,
358 unsigned int flags
, unsigned int hctx_idx
)
360 struct blk_mq_alloc_data alloc_data
= { .flags
= flags
};
366 * If the tag allocator sleeps we could get an allocation for a
367 * different hardware context. No need to complicate the low level
368 * allocator for this for the rare use case of a command tied to
371 if (WARN_ON_ONCE(!(flags
& BLK_MQ_REQ_NOWAIT
)))
372 return ERR_PTR(-EINVAL
);
374 if (hctx_idx
>= q
->nr_hw_queues
)
375 return ERR_PTR(-EIO
);
377 ret
= blk_queue_enter(q
, true);
382 * Check if the hardware context is actually mapped to anything.
383 * If not tell the caller that it should skip this queue.
385 alloc_data
.hctx
= q
->queue_hw_ctx
[hctx_idx
];
386 if (!blk_mq_hw_queue_mapped(alloc_data
.hctx
)) {
388 return ERR_PTR(-EXDEV
);
390 cpu
= cpumask_first(alloc_data
.hctx
->cpumask
);
391 alloc_data
.ctx
= __blk_mq_get_ctx(q
, cpu
);
393 rq
= blk_mq_get_request(q
, NULL
, rw
, &alloc_data
);
398 return ERR_PTR(-EWOULDBLOCK
);
402 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx
);
404 void blk_mq_free_request(struct request
*rq
)
406 struct request_queue
*q
= rq
->q
;
407 struct elevator_queue
*e
= q
->elevator
;
408 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
409 struct blk_mq_hw_ctx
*hctx
= blk_mq_map_queue(q
, ctx
->cpu
);
410 const int sched_tag
= rq
->internal_tag
;
412 if (rq
->rq_flags
& RQF_ELVPRIV
) {
413 if (e
&& e
->type
->ops
.mq
.finish_request
)
414 e
->type
->ops
.mq
.finish_request(rq
);
416 put_io_context(rq
->elv
.icq
->ioc
);
421 ctx
->rq_completed
[rq_is_sync(rq
)]++;
422 if (rq
->rq_flags
& RQF_MQ_INFLIGHT
)
423 atomic_dec(&hctx
->nr_active
);
425 wbt_done(q
->rq_wb
, &rq
->issue_stat
);
428 clear_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
429 clear_bit(REQ_ATOM_POLL_SLEPT
, &rq
->atomic_flags
);
431 blk_mq_put_tag(hctx
, hctx
->tags
, ctx
, rq
->tag
);
433 blk_mq_put_tag(hctx
, hctx
->sched_tags
, ctx
, sched_tag
);
434 blk_mq_sched_restart(hctx
);
437 EXPORT_SYMBOL_GPL(blk_mq_free_request
);
439 inline void __blk_mq_end_request(struct request
*rq
, blk_status_t error
)
441 blk_account_io_done(rq
);
444 wbt_done(rq
->q
->rq_wb
, &rq
->issue_stat
);
445 rq
->end_io(rq
, error
);
447 if (unlikely(blk_bidi_rq(rq
)))
448 blk_mq_free_request(rq
->next_rq
);
449 blk_mq_free_request(rq
);
452 EXPORT_SYMBOL(__blk_mq_end_request
);
454 void blk_mq_end_request(struct request
*rq
, blk_status_t error
)
456 if (blk_update_request(rq
, error
, blk_rq_bytes(rq
)))
458 __blk_mq_end_request(rq
, error
);
460 EXPORT_SYMBOL(blk_mq_end_request
);
462 static void __blk_mq_complete_request_remote(void *data
)
464 struct request
*rq
= data
;
466 rq
->q
->softirq_done_fn(rq
);
469 static void __blk_mq_complete_request(struct request
*rq
)
471 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
475 if (rq
->internal_tag
!= -1)
476 blk_mq_sched_completed_request(rq
);
477 if (rq
->rq_flags
& RQF_STATS
) {
478 blk_mq_poll_stats_start(rq
->q
);
482 if (!test_bit(QUEUE_FLAG_SAME_COMP
, &rq
->q
->queue_flags
)) {
483 rq
->q
->softirq_done_fn(rq
);
488 if (!test_bit(QUEUE_FLAG_SAME_FORCE
, &rq
->q
->queue_flags
))
489 shared
= cpus_share_cache(cpu
, ctx
->cpu
);
491 if (cpu
!= ctx
->cpu
&& !shared
&& cpu_online(ctx
->cpu
)) {
492 rq
->csd
.func
= __blk_mq_complete_request_remote
;
495 smp_call_function_single_async(ctx
->cpu
, &rq
->csd
);
497 rq
->q
->softirq_done_fn(rq
);
503 * blk_mq_complete_request - end I/O on a request
504 * @rq: the request being processed
507 * Ends all I/O on a request. It does not handle partial completions.
508 * The actual completion happens out-of-order, through a IPI handler.
510 void blk_mq_complete_request(struct request
*rq
)
512 struct request_queue
*q
= rq
->q
;
514 if (unlikely(blk_should_fake_timeout(q
)))
516 if (!blk_mark_rq_complete(rq
))
517 __blk_mq_complete_request(rq
);
519 EXPORT_SYMBOL(blk_mq_complete_request
);
521 int blk_mq_request_started(struct request
*rq
)
523 return test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
525 EXPORT_SYMBOL_GPL(blk_mq_request_started
);
527 void blk_mq_start_request(struct request
*rq
)
529 struct request_queue
*q
= rq
->q
;
531 blk_mq_sched_started_request(rq
);
533 trace_block_rq_issue(q
, rq
);
535 if (test_bit(QUEUE_FLAG_STATS
, &q
->queue_flags
)) {
536 blk_stat_set_issue(&rq
->issue_stat
, blk_rq_sectors(rq
));
537 rq
->rq_flags
|= RQF_STATS
;
538 wbt_issue(q
->rq_wb
, &rq
->issue_stat
);
544 * Ensure that ->deadline is visible before set the started
545 * flag and clear the completed flag.
547 smp_mb__before_atomic();
550 * Mark us as started and clear complete. Complete might have been
551 * set if requeue raced with timeout, which then marked it as
552 * complete. So be sure to clear complete again when we start
553 * the request, otherwise we'll ignore the completion event.
555 if (!test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
))
556 set_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
557 if (test_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
))
558 clear_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
);
560 if (q
->dma_drain_size
&& blk_rq_bytes(rq
)) {
562 * Make sure space for the drain appears. We know we can do
563 * this because max_hw_segments has been adjusted to be one
564 * fewer than the device can handle.
566 rq
->nr_phys_segments
++;
569 EXPORT_SYMBOL(blk_mq_start_request
);
572 * When we reach here because queue is busy, REQ_ATOM_COMPLETE
573 * flag isn't set yet, so there may be race with timeout handler,
574 * but given rq->deadline is just set in .queue_rq() under
575 * this situation, the race won't be possible in reality because
576 * rq->timeout should be set as big enough to cover the window
577 * between blk_mq_start_request() called from .queue_rq() and
578 * clearing REQ_ATOM_STARTED here.
580 static void __blk_mq_requeue_request(struct request
*rq
)
582 struct request_queue
*q
= rq
->q
;
584 trace_block_rq_requeue(q
, rq
);
585 wbt_requeue(q
->rq_wb
, &rq
->issue_stat
);
586 blk_mq_sched_requeue_request(rq
);
588 if (test_and_clear_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
)) {
589 if (q
->dma_drain_size
&& blk_rq_bytes(rq
))
590 rq
->nr_phys_segments
--;
594 void blk_mq_requeue_request(struct request
*rq
, bool kick_requeue_list
)
596 __blk_mq_requeue_request(rq
);
598 BUG_ON(blk_queued_rq(rq
));
599 blk_mq_add_to_requeue_list(rq
, true, kick_requeue_list
);
601 EXPORT_SYMBOL(blk_mq_requeue_request
);
603 static void blk_mq_requeue_work(struct work_struct
*work
)
605 struct request_queue
*q
=
606 container_of(work
, struct request_queue
, requeue_work
.work
);
608 struct request
*rq
, *next
;
611 spin_lock_irqsave(&q
->requeue_lock
, flags
);
612 list_splice_init(&q
->requeue_list
, &rq_list
);
613 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
615 list_for_each_entry_safe(rq
, next
, &rq_list
, queuelist
) {
616 if (!(rq
->rq_flags
& RQF_SOFTBARRIER
))
619 rq
->rq_flags
&= ~RQF_SOFTBARRIER
;
620 list_del_init(&rq
->queuelist
);
621 blk_mq_sched_insert_request(rq
, true, false, false, true);
624 while (!list_empty(&rq_list
)) {
625 rq
= list_entry(rq_list
.next
, struct request
, queuelist
);
626 list_del_init(&rq
->queuelist
);
627 blk_mq_sched_insert_request(rq
, false, false, false, true);
630 blk_mq_run_hw_queues(q
, false);
633 void blk_mq_add_to_requeue_list(struct request
*rq
, bool at_head
,
634 bool kick_requeue_list
)
636 struct request_queue
*q
= rq
->q
;
640 * We abuse this flag that is otherwise used by the I/O scheduler to
641 * request head insertation from the workqueue.
643 BUG_ON(rq
->rq_flags
& RQF_SOFTBARRIER
);
645 spin_lock_irqsave(&q
->requeue_lock
, flags
);
647 rq
->rq_flags
|= RQF_SOFTBARRIER
;
648 list_add(&rq
->queuelist
, &q
->requeue_list
);
650 list_add_tail(&rq
->queuelist
, &q
->requeue_list
);
652 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
654 if (kick_requeue_list
)
655 blk_mq_kick_requeue_list(q
);
657 EXPORT_SYMBOL(blk_mq_add_to_requeue_list
);
659 void blk_mq_kick_requeue_list(struct request_queue
*q
)
661 kblockd_schedule_delayed_work(&q
->requeue_work
, 0);
663 EXPORT_SYMBOL(blk_mq_kick_requeue_list
);
665 void blk_mq_delay_kick_requeue_list(struct request_queue
*q
,
668 kblockd_schedule_delayed_work(&q
->requeue_work
,
669 msecs_to_jiffies(msecs
));
671 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list
);
673 struct request
*blk_mq_tag_to_rq(struct blk_mq_tags
*tags
, unsigned int tag
)
675 if (tag
< tags
->nr_tags
) {
676 prefetch(tags
->rqs
[tag
]);
677 return tags
->rqs
[tag
];
682 EXPORT_SYMBOL(blk_mq_tag_to_rq
);
684 struct blk_mq_timeout_data
{
686 unsigned int next_set
;
689 void blk_mq_rq_timed_out(struct request
*req
, bool reserved
)
691 const struct blk_mq_ops
*ops
= req
->q
->mq_ops
;
692 enum blk_eh_timer_return ret
= BLK_EH_RESET_TIMER
;
695 * We know that complete is set at this point. If STARTED isn't set
696 * anymore, then the request isn't active and the "timeout" should
697 * just be ignored. This can happen due to the bitflag ordering.
698 * Timeout first checks if STARTED is set, and if it is, assumes
699 * the request is active. But if we race with completion, then
700 * both flags will get cleared. So check here again, and ignore
701 * a timeout event with a request that isn't active.
703 if (!test_bit(REQ_ATOM_STARTED
, &req
->atomic_flags
))
707 ret
= ops
->timeout(req
, reserved
);
711 __blk_mq_complete_request(req
);
713 case BLK_EH_RESET_TIMER
:
715 blk_clear_rq_complete(req
);
717 case BLK_EH_NOT_HANDLED
:
720 printk(KERN_ERR
"block: bad eh return: %d\n", ret
);
725 static void blk_mq_check_expired(struct blk_mq_hw_ctx
*hctx
,
726 struct request
*rq
, void *priv
, bool reserved
)
728 struct blk_mq_timeout_data
*data
= priv
;
730 if (!test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
))
734 * The rq being checked may have been freed and reallocated
735 * out already here, we avoid this race by checking rq->deadline
736 * and REQ_ATOM_COMPLETE flag together:
738 * - if rq->deadline is observed as new value because of
739 * reusing, the rq won't be timed out because of timing.
740 * - if rq->deadline is observed as previous value,
741 * REQ_ATOM_COMPLETE flag won't be cleared in reuse path
742 * because we put a barrier between setting rq->deadline
743 * and clearing the flag in blk_mq_start_request(), so
744 * this rq won't be timed out too.
746 if (time_after_eq(jiffies
, rq
->deadline
)) {
747 if (!blk_mark_rq_complete(rq
))
748 blk_mq_rq_timed_out(rq
, reserved
);
749 } else if (!data
->next_set
|| time_after(data
->next
, rq
->deadline
)) {
750 data
->next
= rq
->deadline
;
755 static void blk_mq_timeout_work(struct work_struct
*work
)
757 struct request_queue
*q
=
758 container_of(work
, struct request_queue
, timeout_work
);
759 struct blk_mq_timeout_data data
= {
765 /* A deadlock might occur if a request is stuck requiring a
766 * timeout at the same time a queue freeze is waiting
767 * completion, since the timeout code would not be able to
768 * acquire the queue reference here.
770 * That's why we don't use blk_queue_enter here; instead, we use
771 * percpu_ref_tryget directly, because we need to be able to
772 * obtain a reference even in the short window between the queue
773 * starting to freeze, by dropping the first reference in
774 * blk_freeze_queue_start, and the moment the last request is
775 * consumed, marked by the instant q_usage_counter reaches
778 if (!percpu_ref_tryget(&q
->q_usage_counter
))
781 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_expired
, &data
);
784 data
.next
= blk_rq_timeout(round_jiffies_up(data
.next
));
785 mod_timer(&q
->timeout
, data
.next
);
787 struct blk_mq_hw_ctx
*hctx
;
789 queue_for_each_hw_ctx(q
, hctx
, i
) {
790 /* the hctx may be unmapped, so check it here */
791 if (blk_mq_hw_queue_mapped(hctx
))
792 blk_mq_tag_idle(hctx
);
798 struct flush_busy_ctx_data
{
799 struct blk_mq_hw_ctx
*hctx
;
800 struct list_head
*list
;
803 static bool flush_busy_ctx(struct sbitmap
*sb
, unsigned int bitnr
, void *data
)
805 struct flush_busy_ctx_data
*flush_data
= data
;
806 struct blk_mq_hw_ctx
*hctx
= flush_data
->hctx
;
807 struct blk_mq_ctx
*ctx
= hctx
->ctxs
[bitnr
];
809 sbitmap_clear_bit(sb
, bitnr
);
810 spin_lock(&ctx
->lock
);
811 list_splice_tail_init(&ctx
->rq_list
, flush_data
->list
);
812 spin_unlock(&ctx
->lock
);
817 * Process software queues that have been marked busy, splicing them
818 * to the for-dispatch
820 void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx
*hctx
, struct list_head
*list
)
822 struct flush_busy_ctx_data data
= {
827 sbitmap_for_each_set(&hctx
->ctx_map
, flush_busy_ctx
, &data
);
829 EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs
);
831 static inline unsigned int queued_to_index(unsigned int queued
)
836 return min(BLK_MQ_MAX_DISPATCH_ORDER
- 1, ilog2(queued
) + 1);
839 bool blk_mq_get_driver_tag(struct request
*rq
, struct blk_mq_hw_ctx
**hctx
,
842 struct blk_mq_alloc_data data
= {
844 .hctx
= blk_mq_map_queue(rq
->q
, rq
->mq_ctx
->cpu
),
845 .flags
= wait
? 0 : BLK_MQ_REQ_NOWAIT
,
848 might_sleep_if(wait
);
853 if (blk_mq_tag_is_reserved(data
.hctx
->sched_tags
, rq
->internal_tag
))
854 data
.flags
|= BLK_MQ_REQ_RESERVED
;
856 rq
->tag
= blk_mq_get_tag(&data
);
858 if (blk_mq_tag_busy(data
.hctx
)) {
859 rq
->rq_flags
|= RQF_MQ_INFLIGHT
;
860 atomic_inc(&data
.hctx
->nr_active
);
862 data
.hctx
->tags
->rqs
[rq
->tag
] = rq
;
868 return rq
->tag
!= -1;
871 static void __blk_mq_put_driver_tag(struct blk_mq_hw_ctx
*hctx
,
874 blk_mq_put_tag(hctx
, hctx
->tags
, rq
->mq_ctx
, rq
->tag
);
877 if (rq
->rq_flags
& RQF_MQ_INFLIGHT
) {
878 rq
->rq_flags
&= ~RQF_MQ_INFLIGHT
;
879 atomic_dec(&hctx
->nr_active
);
883 static void blk_mq_put_driver_tag_hctx(struct blk_mq_hw_ctx
*hctx
,
886 if (rq
->tag
== -1 || rq
->internal_tag
== -1)
889 __blk_mq_put_driver_tag(hctx
, rq
);
892 static void blk_mq_put_driver_tag(struct request
*rq
)
894 struct blk_mq_hw_ctx
*hctx
;
896 if (rq
->tag
== -1 || rq
->internal_tag
== -1)
899 hctx
= blk_mq_map_queue(rq
->q
, rq
->mq_ctx
->cpu
);
900 __blk_mq_put_driver_tag(hctx
, rq
);
904 * If we fail getting a driver tag because all the driver tags are already
905 * assigned and on the dispatch list, BUT the first entry does not have a
906 * tag, then we could deadlock. For that case, move entries with assigned
907 * driver tags to the front, leaving the set of tagged requests in the
908 * same order, and the untagged set in the same order.
910 static bool reorder_tags_to_front(struct list_head
*list
)
912 struct request
*rq
, *tmp
, *first
= NULL
;
914 list_for_each_entry_safe_reverse(rq
, tmp
, list
, queuelist
) {
918 list_move(&rq
->queuelist
, list
);
924 return first
!= NULL
;
927 static int blk_mq_dispatch_wake(wait_queue_t
*wait
, unsigned mode
, int flags
,
930 struct blk_mq_hw_ctx
*hctx
;
932 hctx
= container_of(wait
, struct blk_mq_hw_ctx
, dispatch_wait
);
934 list_del(&wait
->task_list
);
935 clear_bit_unlock(BLK_MQ_S_TAG_WAITING
, &hctx
->state
);
936 blk_mq_run_hw_queue(hctx
, true);
940 static bool blk_mq_dispatch_wait_add(struct blk_mq_hw_ctx
*hctx
)
942 struct sbq_wait_state
*ws
;
945 * The TAG_WAITING bit serves as a lock protecting hctx->dispatch_wait.
946 * The thread which wins the race to grab this bit adds the hardware
947 * queue to the wait queue.
949 if (test_bit(BLK_MQ_S_TAG_WAITING
, &hctx
->state
) ||
950 test_and_set_bit_lock(BLK_MQ_S_TAG_WAITING
, &hctx
->state
))
953 init_waitqueue_func_entry(&hctx
->dispatch_wait
, blk_mq_dispatch_wake
);
954 ws
= bt_wait_ptr(&hctx
->tags
->bitmap_tags
, hctx
);
957 * As soon as this returns, it's no longer safe to fiddle with
958 * hctx->dispatch_wait, since a completion can wake up the wait queue
959 * and unlock the bit.
961 add_wait_queue(&ws
->wait
, &hctx
->dispatch_wait
);
965 bool blk_mq_dispatch_rq_list(struct request_queue
*q
, struct list_head
*list
)
967 struct blk_mq_hw_ctx
*hctx
;
971 if (list_empty(list
))
975 * Now process all the entries, sending them to the driver.
979 struct blk_mq_queue_data bd
;
982 rq
= list_first_entry(list
, struct request
, queuelist
);
983 if (!blk_mq_get_driver_tag(rq
, &hctx
, false)) {
984 if (!queued
&& reorder_tags_to_front(list
))
988 * The initial allocation attempt failed, so we need to
989 * rerun the hardware queue when a tag is freed.
991 if (!blk_mq_dispatch_wait_add(hctx
))
995 * It's possible that a tag was freed in the window
996 * between the allocation failure and adding the
997 * hardware queue to the wait queue.
999 if (!blk_mq_get_driver_tag(rq
, &hctx
, false))
1003 list_del_init(&rq
->queuelist
);
1008 * Flag last if we have no more requests, or if we have more
1009 * but can't assign a driver tag to it.
1011 if (list_empty(list
))
1014 struct request
*nxt
;
1016 nxt
= list_first_entry(list
, struct request
, queuelist
);
1017 bd
.last
= !blk_mq_get_driver_tag(nxt
, NULL
, false);
1020 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1021 if (ret
== BLK_STS_RESOURCE
) {
1022 blk_mq_put_driver_tag_hctx(hctx
, rq
);
1023 list_add(&rq
->queuelist
, list
);
1024 __blk_mq_requeue_request(rq
);
1028 if (unlikely(ret
!= BLK_STS_OK
)) {
1030 blk_mq_end_request(rq
, BLK_STS_IOERR
);
1035 } while (!list_empty(list
));
1037 hctx
->dispatched
[queued_to_index(queued
)]++;
1040 * Any items that need requeuing? Stuff them into hctx->dispatch,
1041 * that is where we will continue on next queue run.
1043 if (!list_empty(list
)) {
1045 * If an I/O scheduler has been configured and we got a driver
1046 * tag for the next request already, free it again.
1048 rq
= list_first_entry(list
, struct request
, queuelist
);
1049 blk_mq_put_driver_tag(rq
);
1051 spin_lock(&hctx
->lock
);
1052 list_splice_init(list
, &hctx
->dispatch
);
1053 spin_unlock(&hctx
->lock
);
1056 * If SCHED_RESTART was set by the caller of this function and
1057 * it is no longer set that means that it was cleared by another
1058 * thread and hence that a queue rerun is needed.
1060 * If TAG_WAITING is set that means that an I/O scheduler has
1061 * been configured and another thread is waiting for a driver
1062 * tag. To guarantee fairness, do not rerun this hardware queue
1063 * but let the other thread grab the driver tag.
1065 * If no I/O scheduler has been configured it is possible that
1066 * the hardware queue got stopped and restarted before requests
1067 * were pushed back onto the dispatch list. Rerun the queue to
1068 * avoid starvation. Notes:
1069 * - blk_mq_run_hw_queue() checks whether or not a queue has
1070 * been stopped before rerunning a queue.
1071 * - Some but not all block drivers stop a queue before
1072 * returning BLK_STS_RESOURCE. Two exceptions are scsi-mq
1075 if (!blk_mq_sched_needs_restart(hctx
) &&
1076 !test_bit(BLK_MQ_S_TAG_WAITING
, &hctx
->state
))
1077 blk_mq_run_hw_queue(hctx
, true);
1080 return (queued
+ errors
) != 0;
1083 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1087 WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx
->cpumask
) &&
1088 cpu_online(hctx
->next_cpu
));
1090 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1092 blk_mq_sched_dispatch_requests(hctx
);
1097 srcu_idx
= srcu_read_lock(&hctx
->queue_rq_srcu
);
1098 blk_mq_sched_dispatch_requests(hctx
);
1099 srcu_read_unlock(&hctx
->queue_rq_srcu
, srcu_idx
);
1104 * It'd be great if the workqueue API had a way to pass
1105 * in a mask and had some smarts for more clever placement.
1106 * For now we just round-robin here, switching for every
1107 * BLK_MQ_CPU_WORK_BATCH queued items.
1109 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx
*hctx
)
1111 if (hctx
->queue
->nr_hw_queues
== 1)
1112 return WORK_CPU_UNBOUND
;
1114 if (--hctx
->next_cpu_batch
<= 0) {
1117 next_cpu
= cpumask_next(hctx
->next_cpu
, hctx
->cpumask
);
1118 if (next_cpu
>= nr_cpu_ids
)
1119 next_cpu
= cpumask_first(hctx
->cpumask
);
1121 hctx
->next_cpu
= next_cpu
;
1122 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
1125 return hctx
->next_cpu
;
1128 static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
,
1129 unsigned long msecs
)
1131 if (unlikely(blk_mq_hctx_stopped(hctx
) ||
1132 !blk_mq_hw_queue_mapped(hctx
)))
1135 if (!async
&& !(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1136 int cpu
= get_cpu();
1137 if (cpumask_test_cpu(cpu
, hctx
->cpumask
)) {
1138 __blk_mq_run_hw_queue(hctx
);
1146 kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx
),
1148 msecs_to_jiffies(msecs
));
1151 void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, unsigned long msecs
)
1153 __blk_mq_delay_run_hw_queue(hctx
, true, msecs
);
1155 EXPORT_SYMBOL(blk_mq_delay_run_hw_queue
);
1157 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1159 __blk_mq_delay_run_hw_queue(hctx
, async
, 0);
1161 EXPORT_SYMBOL(blk_mq_run_hw_queue
);
1163 void blk_mq_run_hw_queues(struct request_queue
*q
, bool async
)
1165 struct blk_mq_hw_ctx
*hctx
;
1168 queue_for_each_hw_ctx(q
, hctx
, i
) {
1169 if (!blk_mq_hctx_has_pending(hctx
) ||
1170 blk_mq_hctx_stopped(hctx
))
1173 blk_mq_run_hw_queue(hctx
, async
);
1176 EXPORT_SYMBOL(blk_mq_run_hw_queues
);
1179 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1180 * @q: request queue.
1182 * The caller is responsible for serializing this function against
1183 * blk_mq_{start,stop}_hw_queue().
1185 bool blk_mq_queue_stopped(struct request_queue
*q
)
1187 struct blk_mq_hw_ctx
*hctx
;
1190 queue_for_each_hw_ctx(q
, hctx
, i
)
1191 if (blk_mq_hctx_stopped(hctx
))
1196 EXPORT_SYMBOL(blk_mq_queue_stopped
);
1199 * This function is often used for pausing .queue_rq() by driver when
1200 * there isn't enough resource or some conditions aren't satisfied, and
1201 * BLK_MQ_RQ_QUEUE_BUSY is usually returned.
1203 * We do not guarantee that dispatch can be drained or blocked
1204 * after blk_mq_stop_hw_queue() returns. Please use
1205 * blk_mq_quiesce_queue() for that requirement.
1207 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1209 cancel_delayed_work(&hctx
->run_work
);
1211 set_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1213 EXPORT_SYMBOL(blk_mq_stop_hw_queue
);
1216 * This function is often used for pausing .queue_rq() by driver when
1217 * there isn't enough resource or some conditions aren't satisfied, and
1218 * BLK_MQ_RQ_QUEUE_BUSY is usually returned.
1220 * We do not guarantee that dispatch can be drained or blocked
1221 * after blk_mq_stop_hw_queues() returns. Please use
1222 * blk_mq_quiesce_queue() for that requirement.
1224 void blk_mq_stop_hw_queues(struct request_queue
*q
)
1226 struct blk_mq_hw_ctx
*hctx
;
1229 queue_for_each_hw_ctx(q
, hctx
, i
)
1230 blk_mq_stop_hw_queue(hctx
);
1232 EXPORT_SYMBOL(blk_mq_stop_hw_queues
);
1234 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1236 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1238 blk_mq_run_hw_queue(hctx
, false);
1240 EXPORT_SYMBOL(blk_mq_start_hw_queue
);
1242 void blk_mq_start_hw_queues(struct request_queue
*q
)
1244 struct blk_mq_hw_ctx
*hctx
;
1247 queue_for_each_hw_ctx(q
, hctx
, i
)
1248 blk_mq_start_hw_queue(hctx
);
1250 EXPORT_SYMBOL(blk_mq_start_hw_queues
);
1252 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1254 if (!blk_mq_hctx_stopped(hctx
))
1257 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1258 blk_mq_run_hw_queue(hctx
, async
);
1260 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue
);
1262 void blk_mq_start_stopped_hw_queues(struct request_queue
*q
, bool async
)
1264 struct blk_mq_hw_ctx
*hctx
;
1267 queue_for_each_hw_ctx(q
, hctx
, i
)
1268 blk_mq_start_stopped_hw_queue(hctx
, async
);
1270 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues
);
1272 static void blk_mq_run_work_fn(struct work_struct
*work
)
1274 struct blk_mq_hw_ctx
*hctx
;
1276 hctx
= container_of(work
, struct blk_mq_hw_ctx
, run_work
.work
);
1279 * If we are stopped, don't run the queue. The exception is if
1280 * BLK_MQ_S_START_ON_RUN is set. For that case, we auto-clear
1281 * the STOPPED bit and run it.
1283 if (test_bit(BLK_MQ_S_STOPPED
, &hctx
->state
)) {
1284 if (!test_bit(BLK_MQ_S_START_ON_RUN
, &hctx
->state
))
1287 clear_bit(BLK_MQ_S_START_ON_RUN
, &hctx
->state
);
1288 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1291 __blk_mq_run_hw_queue(hctx
);
1295 void blk_mq_delay_queue(struct blk_mq_hw_ctx
*hctx
, unsigned long msecs
)
1297 if (unlikely(!blk_mq_hw_queue_mapped(hctx
)))
1301 * Stop the hw queue, then modify currently delayed work.
1302 * This should prevent us from running the queue prematurely.
1303 * Mark the queue as auto-clearing STOPPED when it runs.
1305 blk_mq_stop_hw_queue(hctx
);
1306 set_bit(BLK_MQ_S_START_ON_RUN
, &hctx
->state
);
1307 kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx
),
1309 msecs_to_jiffies(msecs
));
1311 EXPORT_SYMBOL(blk_mq_delay_queue
);
1313 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx
*hctx
,
1317 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1319 trace_block_rq_insert(hctx
->queue
, rq
);
1322 list_add(&rq
->queuelist
, &ctx
->rq_list
);
1324 list_add_tail(&rq
->queuelist
, &ctx
->rq_list
);
1327 void __blk_mq_insert_request(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
,
1330 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1332 __blk_mq_insert_req_list(hctx
, rq
, at_head
);
1333 blk_mq_hctx_mark_pending(hctx
, ctx
);
1336 void blk_mq_insert_requests(struct blk_mq_hw_ctx
*hctx
, struct blk_mq_ctx
*ctx
,
1337 struct list_head
*list
)
1341 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1344 spin_lock(&ctx
->lock
);
1345 while (!list_empty(list
)) {
1348 rq
= list_first_entry(list
, struct request
, queuelist
);
1349 BUG_ON(rq
->mq_ctx
!= ctx
);
1350 list_del_init(&rq
->queuelist
);
1351 __blk_mq_insert_req_list(hctx
, rq
, false);
1353 blk_mq_hctx_mark_pending(hctx
, ctx
);
1354 spin_unlock(&ctx
->lock
);
1357 static int plug_ctx_cmp(void *priv
, struct list_head
*a
, struct list_head
*b
)
1359 struct request
*rqa
= container_of(a
, struct request
, queuelist
);
1360 struct request
*rqb
= container_of(b
, struct request
, queuelist
);
1362 return !(rqa
->mq_ctx
< rqb
->mq_ctx
||
1363 (rqa
->mq_ctx
== rqb
->mq_ctx
&&
1364 blk_rq_pos(rqa
) < blk_rq_pos(rqb
)));
1367 void blk_mq_flush_plug_list(struct blk_plug
*plug
, bool from_schedule
)
1369 struct blk_mq_ctx
*this_ctx
;
1370 struct request_queue
*this_q
;
1373 LIST_HEAD(ctx_list
);
1376 list_splice_init(&plug
->mq_list
, &list
);
1378 list_sort(NULL
, &list
, plug_ctx_cmp
);
1384 while (!list_empty(&list
)) {
1385 rq
= list_entry_rq(list
.next
);
1386 list_del_init(&rq
->queuelist
);
1388 if (rq
->mq_ctx
!= this_ctx
) {
1390 trace_block_unplug(this_q
, depth
, from_schedule
);
1391 blk_mq_sched_insert_requests(this_q
, this_ctx
,
1396 this_ctx
= rq
->mq_ctx
;
1402 list_add_tail(&rq
->queuelist
, &ctx_list
);
1406 * If 'this_ctx' is set, we know we have entries to complete
1407 * on 'ctx_list'. Do those.
1410 trace_block_unplug(this_q
, depth
, from_schedule
);
1411 blk_mq_sched_insert_requests(this_q
, this_ctx
, &ctx_list
,
1416 static void blk_mq_bio_to_request(struct request
*rq
, struct bio
*bio
)
1418 blk_init_request_from_bio(rq
, bio
);
1420 blk_account_io_start(rq
, true);
1423 static inline bool hctx_allow_merges(struct blk_mq_hw_ctx
*hctx
)
1425 return (hctx
->flags
& BLK_MQ_F_SHOULD_MERGE
) &&
1426 !blk_queue_nomerges(hctx
->queue
);
1429 static inline void blk_mq_queue_io(struct blk_mq_hw_ctx
*hctx
,
1430 struct blk_mq_ctx
*ctx
,
1433 spin_lock(&ctx
->lock
);
1434 __blk_mq_insert_request(hctx
, rq
, false);
1435 spin_unlock(&ctx
->lock
);
1438 static blk_qc_t
request_to_qc_t(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
)
1441 return blk_tag_to_qc_t(rq
->tag
, hctx
->queue_num
, false);
1443 return blk_tag_to_qc_t(rq
->internal_tag
, hctx
->queue_num
, true);
1446 static void __blk_mq_try_issue_directly(struct blk_mq_hw_ctx
*hctx
,
1448 blk_qc_t
*cookie
, bool may_sleep
)
1450 struct request_queue
*q
= rq
->q
;
1451 struct blk_mq_queue_data bd
= {
1455 blk_qc_t new_cookie
;
1457 bool run_queue
= true;
1459 /* RCU or SRCU read lock is needed before checking quiesced flag */
1460 if (blk_mq_hctx_stopped(hctx
) || blk_queue_quiesced(q
)) {
1468 if (!blk_mq_get_driver_tag(rq
, NULL
, false))
1471 new_cookie
= request_to_qc_t(hctx
, rq
);
1474 * For OK queue, we are done. For error, kill it. Any other
1475 * error (busy), just add it to our list as we previously
1478 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1481 *cookie
= new_cookie
;
1483 case BLK_STS_RESOURCE
:
1484 __blk_mq_requeue_request(rq
);
1487 *cookie
= BLK_QC_T_NONE
;
1488 blk_mq_end_request(rq
, ret
);
1493 blk_mq_sched_insert_request(rq
, false, run_queue
, false, may_sleep
);
1496 static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx
*hctx
,
1497 struct request
*rq
, blk_qc_t
*cookie
)
1499 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1501 __blk_mq_try_issue_directly(hctx
, rq
, cookie
, false);
1504 unsigned int srcu_idx
;
1508 srcu_idx
= srcu_read_lock(&hctx
->queue_rq_srcu
);
1509 __blk_mq_try_issue_directly(hctx
, rq
, cookie
, true);
1510 srcu_read_unlock(&hctx
->queue_rq_srcu
, srcu_idx
);
1514 static blk_qc_t
blk_mq_make_request(struct request_queue
*q
, struct bio
*bio
)
1516 const int is_sync
= op_is_sync(bio
->bi_opf
);
1517 const int is_flush_fua
= op_is_flush(bio
->bi_opf
);
1518 struct blk_mq_alloc_data data
= { .flags
= 0 };
1520 unsigned int request_count
= 0;
1521 struct blk_plug
*plug
;
1522 struct request
*same_queue_rq
= NULL
;
1524 unsigned int wb_acct
;
1526 blk_queue_bounce(q
, &bio
);
1528 blk_queue_split(q
, &bio
);
1530 if (bio_integrity_enabled(bio
) && bio_integrity_prep(bio
)) {
1532 return BLK_QC_T_NONE
;
1535 if (!is_flush_fua
&& !blk_queue_nomerges(q
) &&
1536 blk_attempt_plug_merge(q
, bio
, &request_count
, &same_queue_rq
))
1537 return BLK_QC_T_NONE
;
1539 if (blk_mq_sched_bio_merge(q
, bio
))
1540 return BLK_QC_T_NONE
;
1542 wb_acct
= wbt_wait(q
->rq_wb
, bio
, NULL
);
1544 trace_block_getrq(q
, bio
, bio
->bi_opf
);
1546 rq
= blk_mq_get_request(q
, bio
, bio
->bi_opf
, &data
);
1547 if (unlikely(!rq
)) {
1548 __wbt_done(q
->rq_wb
, wb_acct
);
1549 if (bio
->bi_opf
& REQ_NOWAIT
)
1550 bio_wouldblock_error(bio
);
1551 return BLK_QC_T_NONE
;
1554 wbt_track(&rq
->issue_stat
, wb_acct
);
1556 cookie
= request_to_qc_t(data
.hctx
, rq
);
1558 plug
= current
->plug
;
1559 if (unlikely(is_flush_fua
)) {
1560 blk_mq_put_ctx(data
.ctx
);
1561 blk_mq_bio_to_request(rq
, bio
);
1563 blk_mq_sched_insert_request(rq
, false, true, true,
1566 blk_insert_flush(rq
);
1567 blk_mq_run_hw_queue(data
.hctx
, true);
1569 } else if (plug
&& q
->nr_hw_queues
== 1) {
1570 struct request
*last
= NULL
;
1572 blk_mq_put_ctx(data
.ctx
);
1573 blk_mq_bio_to_request(rq
, bio
);
1576 * @request_count may become stale because of schedule
1577 * out, so check the list again.
1579 if (list_empty(&plug
->mq_list
))
1581 else if (blk_queue_nomerges(q
))
1582 request_count
= blk_plug_queued_count(q
);
1585 trace_block_plug(q
);
1587 last
= list_entry_rq(plug
->mq_list
.prev
);
1589 if (request_count
>= BLK_MAX_REQUEST_COUNT
|| (last
&&
1590 blk_rq_bytes(last
) >= BLK_PLUG_FLUSH_SIZE
)) {
1591 blk_flush_plug_list(plug
, false);
1592 trace_block_plug(q
);
1595 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1596 } else if (plug
&& !blk_queue_nomerges(q
)) {
1597 blk_mq_bio_to_request(rq
, bio
);
1600 * We do limited plugging. If the bio can be merged, do that.
1601 * Otherwise the existing request in the plug list will be
1602 * issued. So the plug list will have one request at most
1603 * The plug list might get flushed before this. If that happens,
1604 * the plug list is empty, and same_queue_rq is invalid.
1606 if (list_empty(&plug
->mq_list
))
1607 same_queue_rq
= NULL
;
1609 list_del_init(&same_queue_rq
->queuelist
);
1610 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1612 blk_mq_put_ctx(data
.ctx
);
1614 if (same_queue_rq
) {
1615 data
.hctx
= blk_mq_map_queue(q
,
1616 same_queue_rq
->mq_ctx
->cpu
);
1617 blk_mq_try_issue_directly(data
.hctx
, same_queue_rq
,
1620 } else if (q
->nr_hw_queues
> 1 && is_sync
) {
1621 blk_mq_put_ctx(data
.ctx
);
1622 blk_mq_bio_to_request(rq
, bio
);
1623 blk_mq_try_issue_directly(data
.hctx
, rq
, &cookie
);
1624 } else if (q
->elevator
) {
1625 blk_mq_put_ctx(data
.ctx
);
1626 blk_mq_bio_to_request(rq
, bio
);
1627 blk_mq_sched_insert_request(rq
, false, true, true, true);
1629 blk_mq_put_ctx(data
.ctx
);
1630 blk_mq_bio_to_request(rq
, bio
);
1631 blk_mq_queue_io(data
.hctx
, data
.ctx
, rq
);
1632 blk_mq_run_hw_queue(data
.hctx
, true);
1638 void blk_mq_free_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
1639 unsigned int hctx_idx
)
1643 if (tags
->rqs
&& set
->ops
->exit_request
) {
1646 for (i
= 0; i
< tags
->nr_tags
; i
++) {
1647 struct request
*rq
= tags
->static_rqs
[i
];
1651 set
->ops
->exit_request(set
, rq
, hctx_idx
);
1652 tags
->static_rqs
[i
] = NULL
;
1656 while (!list_empty(&tags
->page_list
)) {
1657 page
= list_first_entry(&tags
->page_list
, struct page
, lru
);
1658 list_del_init(&page
->lru
);
1660 * Remove kmemleak object previously allocated in
1661 * blk_mq_init_rq_map().
1663 kmemleak_free(page_address(page
));
1664 __free_pages(page
, page
->private);
1668 void blk_mq_free_rq_map(struct blk_mq_tags
*tags
)
1672 kfree(tags
->static_rqs
);
1673 tags
->static_rqs
= NULL
;
1675 blk_mq_free_tags(tags
);
1678 struct blk_mq_tags
*blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
,
1679 unsigned int hctx_idx
,
1680 unsigned int nr_tags
,
1681 unsigned int reserved_tags
)
1683 struct blk_mq_tags
*tags
;
1686 node
= blk_mq_hw_queue_to_node(set
->mq_map
, hctx_idx
);
1687 if (node
== NUMA_NO_NODE
)
1688 node
= set
->numa_node
;
1690 tags
= blk_mq_init_tags(nr_tags
, reserved_tags
, node
,
1691 BLK_MQ_FLAG_TO_ALLOC_POLICY(set
->flags
));
1695 tags
->rqs
= kzalloc_node(nr_tags
* sizeof(struct request
*),
1696 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
1699 blk_mq_free_tags(tags
);
1703 tags
->static_rqs
= kzalloc_node(nr_tags
* sizeof(struct request
*),
1704 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
1706 if (!tags
->static_rqs
) {
1708 blk_mq_free_tags(tags
);
1715 static size_t order_to_size(unsigned int order
)
1717 return (size_t)PAGE_SIZE
<< order
;
1720 int blk_mq_alloc_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
1721 unsigned int hctx_idx
, unsigned int depth
)
1723 unsigned int i
, j
, entries_per_page
, max_order
= 4;
1724 size_t rq_size
, left
;
1727 node
= blk_mq_hw_queue_to_node(set
->mq_map
, hctx_idx
);
1728 if (node
== NUMA_NO_NODE
)
1729 node
= set
->numa_node
;
1731 INIT_LIST_HEAD(&tags
->page_list
);
1734 * rq_size is the size of the request plus driver payload, rounded
1735 * to the cacheline size
1737 rq_size
= round_up(sizeof(struct request
) + set
->cmd_size
,
1739 left
= rq_size
* depth
;
1741 for (i
= 0; i
< depth
; ) {
1742 int this_order
= max_order
;
1747 while (this_order
&& left
< order_to_size(this_order
- 1))
1751 page
= alloc_pages_node(node
,
1752 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
| __GFP_ZERO
,
1758 if (order_to_size(this_order
) < rq_size
)
1765 page
->private = this_order
;
1766 list_add_tail(&page
->lru
, &tags
->page_list
);
1768 p
= page_address(page
);
1770 * Allow kmemleak to scan these pages as they contain pointers
1771 * to additional allocations like via ops->init_request().
1773 kmemleak_alloc(p
, order_to_size(this_order
), 1, GFP_NOIO
);
1774 entries_per_page
= order_to_size(this_order
) / rq_size
;
1775 to_do
= min(entries_per_page
, depth
- i
);
1776 left
-= to_do
* rq_size
;
1777 for (j
= 0; j
< to_do
; j
++) {
1778 struct request
*rq
= p
;
1780 tags
->static_rqs
[i
] = rq
;
1781 if (set
->ops
->init_request
) {
1782 if (set
->ops
->init_request(set
, rq
, hctx_idx
,
1784 tags
->static_rqs
[i
] = NULL
;
1796 blk_mq_free_rqs(set
, tags
, hctx_idx
);
1801 * 'cpu' is going away. splice any existing rq_list entries from this
1802 * software queue to the hw queue dispatch list, and ensure that it
1805 static int blk_mq_hctx_notify_dead(unsigned int cpu
, struct hlist_node
*node
)
1807 struct blk_mq_hw_ctx
*hctx
;
1808 struct blk_mq_ctx
*ctx
;
1811 hctx
= hlist_entry_safe(node
, struct blk_mq_hw_ctx
, cpuhp_dead
);
1812 ctx
= __blk_mq_get_ctx(hctx
->queue
, cpu
);
1814 spin_lock(&ctx
->lock
);
1815 if (!list_empty(&ctx
->rq_list
)) {
1816 list_splice_init(&ctx
->rq_list
, &tmp
);
1817 blk_mq_hctx_clear_pending(hctx
, ctx
);
1819 spin_unlock(&ctx
->lock
);
1821 if (list_empty(&tmp
))
1824 spin_lock(&hctx
->lock
);
1825 list_splice_tail_init(&tmp
, &hctx
->dispatch
);
1826 spin_unlock(&hctx
->lock
);
1828 blk_mq_run_hw_queue(hctx
, true);
1832 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx
*hctx
)
1834 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD
,
1838 /* hctx->ctxs will be freed in queue's release handler */
1839 static void blk_mq_exit_hctx(struct request_queue
*q
,
1840 struct blk_mq_tag_set
*set
,
1841 struct blk_mq_hw_ctx
*hctx
, unsigned int hctx_idx
)
1843 blk_mq_debugfs_unregister_hctx(hctx
);
1845 blk_mq_tag_idle(hctx
);
1847 if (set
->ops
->exit_request
)
1848 set
->ops
->exit_request(set
, hctx
->fq
->flush_rq
, hctx_idx
);
1850 blk_mq_sched_exit_hctx(q
, hctx
, hctx_idx
);
1852 if (set
->ops
->exit_hctx
)
1853 set
->ops
->exit_hctx(hctx
, hctx_idx
);
1855 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
1856 cleanup_srcu_struct(&hctx
->queue_rq_srcu
);
1858 blk_mq_remove_cpuhp(hctx
);
1859 blk_free_flush_queue(hctx
->fq
);
1860 sbitmap_free(&hctx
->ctx_map
);
1863 static void blk_mq_exit_hw_queues(struct request_queue
*q
,
1864 struct blk_mq_tag_set
*set
, int nr_queue
)
1866 struct blk_mq_hw_ctx
*hctx
;
1869 queue_for_each_hw_ctx(q
, hctx
, i
) {
1872 blk_mq_exit_hctx(q
, set
, hctx
, i
);
1876 static int blk_mq_init_hctx(struct request_queue
*q
,
1877 struct blk_mq_tag_set
*set
,
1878 struct blk_mq_hw_ctx
*hctx
, unsigned hctx_idx
)
1882 node
= hctx
->numa_node
;
1883 if (node
== NUMA_NO_NODE
)
1884 node
= hctx
->numa_node
= set
->numa_node
;
1886 INIT_DELAYED_WORK(&hctx
->run_work
, blk_mq_run_work_fn
);
1887 spin_lock_init(&hctx
->lock
);
1888 INIT_LIST_HEAD(&hctx
->dispatch
);
1890 hctx
->queue_num
= hctx_idx
;
1891 hctx
->flags
= set
->flags
& ~BLK_MQ_F_TAG_SHARED
;
1893 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD
, &hctx
->cpuhp_dead
);
1895 hctx
->tags
= set
->tags
[hctx_idx
];
1898 * Allocate space for all possible cpus to avoid allocation at
1901 hctx
->ctxs
= kmalloc_node(nr_cpu_ids
* sizeof(void *),
1904 goto unregister_cpu_notifier
;
1906 if (sbitmap_init_node(&hctx
->ctx_map
, nr_cpu_ids
, ilog2(8), GFP_KERNEL
,
1912 if (set
->ops
->init_hctx
&&
1913 set
->ops
->init_hctx(hctx
, set
->driver_data
, hctx_idx
))
1916 if (blk_mq_sched_init_hctx(q
, hctx
, hctx_idx
))
1919 hctx
->fq
= blk_alloc_flush_queue(q
, hctx
->numa_node
, set
->cmd_size
);
1921 goto sched_exit_hctx
;
1923 if (set
->ops
->init_request
&&
1924 set
->ops
->init_request(set
, hctx
->fq
->flush_rq
, hctx_idx
,
1928 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
1929 init_srcu_struct(&hctx
->queue_rq_srcu
);
1931 blk_mq_debugfs_register_hctx(q
, hctx
);
1938 blk_mq_sched_exit_hctx(q
, hctx
, hctx_idx
);
1940 if (set
->ops
->exit_hctx
)
1941 set
->ops
->exit_hctx(hctx
, hctx_idx
);
1943 sbitmap_free(&hctx
->ctx_map
);
1946 unregister_cpu_notifier
:
1947 blk_mq_remove_cpuhp(hctx
);
1951 static void blk_mq_init_cpu_queues(struct request_queue
*q
,
1952 unsigned int nr_hw_queues
)
1956 for_each_possible_cpu(i
) {
1957 struct blk_mq_ctx
*__ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
1958 struct blk_mq_hw_ctx
*hctx
;
1961 spin_lock_init(&__ctx
->lock
);
1962 INIT_LIST_HEAD(&__ctx
->rq_list
);
1965 /* If the cpu isn't online, the cpu is mapped to first hctx */
1969 hctx
= blk_mq_map_queue(q
, i
);
1972 * Set local node, IFF we have more than one hw queue. If
1973 * not, we remain on the home node of the device
1975 if (nr_hw_queues
> 1 && hctx
->numa_node
== NUMA_NO_NODE
)
1976 hctx
->numa_node
= local_memory_node(cpu_to_node(i
));
1980 static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
, int hctx_idx
)
1984 set
->tags
[hctx_idx
] = blk_mq_alloc_rq_map(set
, hctx_idx
,
1985 set
->queue_depth
, set
->reserved_tags
);
1986 if (!set
->tags
[hctx_idx
])
1989 ret
= blk_mq_alloc_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
,
1994 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
1995 set
->tags
[hctx_idx
] = NULL
;
1999 static void blk_mq_free_map_and_requests(struct blk_mq_tag_set
*set
,
2000 unsigned int hctx_idx
)
2002 if (set
->tags
[hctx_idx
]) {
2003 blk_mq_free_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
);
2004 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
2005 set
->tags
[hctx_idx
] = NULL
;
2009 static void blk_mq_map_swqueue(struct request_queue
*q
,
2010 const struct cpumask
*online_mask
)
2012 unsigned int i
, hctx_idx
;
2013 struct blk_mq_hw_ctx
*hctx
;
2014 struct blk_mq_ctx
*ctx
;
2015 struct blk_mq_tag_set
*set
= q
->tag_set
;
2018 * Avoid others reading imcomplete hctx->cpumask through sysfs
2020 mutex_lock(&q
->sysfs_lock
);
2022 queue_for_each_hw_ctx(q
, hctx
, i
) {
2023 cpumask_clear(hctx
->cpumask
);
2028 * Map software to hardware queues
2030 for_each_possible_cpu(i
) {
2031 /* If the cpu isn't online, the cpu is mapped to first hctx */
2032 if (!cpumask_test_cpu(i
, online_mask
))
2035 hctx_idx
= q
->mq_map
[i
];
2036 /* unmapped hw queue can be remapped after CPU topo changed */
2037 if (!set
->tags
[hctx_idx
] &&
2038 !__blk_mq_alloc_rq_map(set
, hctx_idx
)) {
2040 * If tags initialization fail for some hctx,
2041 * that hctx won't be brought online. In this
2042 * case, remap the current ctx to hctx[0] which
2043 * is guaranteed to always have tags allocated
2048 ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
2049 hctx
= blk_mq_map_queue(q
, i
);
2051 cpumask_set_cpu(i
, hctx
->cpumask
);
2052 ctx
->index_hw
= hctx
->nr_ctx
;
2053 hctx
->ctxs
[hctx
->nr_ctx
++] = ctx
;
2056 mutex_unlock(&q
->sysfs_lock
);
2058 queue_for_each_hw_ctx(q
, hctx
, i
) {
2060 * If no software queues are mapped to this hardware queue,
2061 * disable it and free the request entries.
2063 if (!hctx
->nr_ctx
) {
2064 /* Never unmap queue 0. We need it as a
2065 * fallback in case of a new remap fails
2068 if (i
&& set
->tags
[i
])
2069 blk_mq_free_map_and_requests(set
, i
);
2075 hctx
->tags
= set
->tags
[i
];
2076 WARN_ON(!hctx
->tags
);
2079 * Set the map size to the number of mapped software queues.
2080 * This is more accurate and more efficient than looping
2081 * over all possibly mapped software queues.
2083 sbitmap_resize(&hctx
->ctx_map
, hctx
->nr_ctx
);
2086 * Initialize batch roundrobin counts
2088 hctx
->next_cpu
= cpumask_first(hctx
->cpumask
);
2089 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
2093 static void queue_set_hctx_shared(struct request_queue
*q
, bool shared
)
2095 struct blk_mq_hw_ctx
*hctx
;
2098 queue_for_each_hw_ctx(q
, hctx
, i
) {
2100 hctx
->flags
|= BLK_MQ_F_TAG_SHARED
;
2102 hctx
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2106 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set
*set
, bool shared
)
2108 struct request_queue
*q
;
2110 lockdep_assert_held(&set
->tag_list_lock
);
2112 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
2113 blk_mq_freeze_queue(q
);
2114 queue_set_hctx_shared(q
, shared
);
2115 blk_mq_unfreeze_queue(q
);
2119 static void blk_mq_del_queue_tag_set(struct request_queue
*q
)
2121 struct blk_mq_tag_set
*set
= q
->tag_set
;
2123 mutex_lock(&set
->tag_list_lock
);
2124 list_del_rcu(&q
->tag_set_list
);
2125 INIT_LIST_HEAD(&q
->tag_set_list
);
2126 if (list_is_singular(&set
->tag_list
)) {
2127 /* just transitioned to unshared */
2128 set
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2129 /* update existing queue */
2130 blk_mq_update_tag_set_depth(set
, false);
2132 mutex_unlock(&set
->tag_list_lock
);
2137 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set
*set
,
2138 struct request_queue
*q
)
2142 mutex_lock(&set
->tag_list_lock
);
2144 /* Check to see if we're transitioning to shared (from 1 to 2 queues). */
2145 if (!list_empty(&set
->tag_list
) && !(set
->flags
& BLK_MQ_F_TAG_SHARED
)) {
2146 set
->flags
|= BLK_MQ_F_TAG_SHARED
;
2147 /* update existing queue */
2148 blk_mq_update_tag_set_depth(set
, true);
2150 if (set
->flags
& BLK_MQ_F_TAG_SHARED
)
2151 queue_set_hctx_shared(q
, true);
2152 list_add_tail_rcu(&q
->tag_set_list
, &set
->tag_list
);
2154 mutex_unlock(&set
->tag_list_lock
);
2158 * It is the actual release handler for mq, but we do it from
2159 * request queue's release handler for avoiding use-after-free
2160 * and headache because q->mq_kobj shouldn't have been introduced,
2161 * but we can't group ctx/kctx kobj without it.
2163 void blk_mq_release(struct request_queue
*q
)
2165 struct blk_mq_hw_ctx
*hctx
;
2168 /* hctx kobj stays in hctx */
2169 queue_for_each_hw_ctx(q
, hctx
, i
) {
2172 kobject_put(&hctx
->kobj
);
2177 kfree(q
->queue_hw_ctx
);
2180 * release .mq_kobj and sw queue's kobject now because
2181 * both share lifetime with request queue.
2183 blk_mq_sysfs_deinit(q
);
2185 free_percpu(q
->queue_ctx
);
2188 struct request_queue
*blk_mq_init_queue(struct blk_mq_tag_set
*set
)
2190 struct request_queue
*uninit_q
, *q
;
2192 uninit_q
= blk_alloc_queue_node(GFP_KERNEL
, set
->numa_node
);
2194 return ERR_PTR(-ENOMEM
);
2196 q
= blk_mq_init_allocated_queue(set
, uninit_q
);
2198 blk_cleanup_queue(uninit_q
);
2202 EXPORT_SYMBOL(blk_mq_init_queue
);
2204 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set
*set
,
2205 struct request_queue
*q
)
2208 struct blk_mq_hw_ctx
**hctxs
= q
->queue_hw_ctx
;
2210 blk_mq_sysfs_unregister(q
);
2211 for (i
= 0; i
< set
->nr_hw_queues
; i
++) {
2217 node
= blk_mq_hw_queue_to_node(q
->mq_map
, i
);
2218 hctxs
[i
] = kzalloc_node(sizeof(struct blk_mq_hw_ctx
),
2223 if (!zalloc_cpumask_var_node(&hctxs
[i
]->cpumask
, GFP_KERNEL
,
2230 atomic_set(&hctxs
[i
]->nr_active
, 0);
2231 hctxs
[i
]->numa_node
= node
;
2232 hctxs
[i
]->queue_num
= i
;
2234 if (blk_mq_init_hctx(q
, set
, hctxs
[i
], i
)) {
2235 free_cpumask_var(hctxs
[i
]->cpumask
);
2240 blk_mq_hctx_kobj_init(hctxs
[i
]);
2242 for (j
= i
; j
< q
->nr_hw_queues
; j
++) {
2243 struct blk_mq_hw_ctx
*hctx
= hctxs
[j
];
2247 blk_mq_free_map_and_requests(set
, j
);
2248 blk_mq_exit_hctx(q
, set
, hctx
, j
);
2249 kobject_put(&hctx
->kobj
);
2254 q
->nr_hw_queues
= i
;
2255 blk_mq_sysfs_register(q
);
2258 struct request_queue
*blk_mq_init_allocated_queue(struct blk_mq_tag_set
*set
,
2259 struct request_queue
*q
)
2261 /* mark the queue as mq asap */
2262 q
->mq_ops
= set
->ops
;
2264 q
->poll_cb
= blk_stat_alloc_callback(blk_mq_poll_stats_fn
,
2265 blk_mq_poll_stats_bkt
,
2266 BLK_MQ_POLL_STATS_BKTS
, q
);
2270 q
->queue_ctx
= alloc_percpu(struct blk_mq_ctx
);
2274 /* init q->mq_kobj and sw queues' kobjects */
2275 blk_mq_sysfs_init(q
);
2277 q
->queue_hw_ctx
= kzalloc_node(nr_cpu_ids
* sizeof(*(q
->queue_hw_ctx
)),
2278 GFP_KERNEL
, set
->numa_node
);
2279 if (!q
->queue_hw_ctx
)
2282 q
->mq_map
= set
->mq_map
;
2284 blk_mq_realloc_hw_ctxs(set
, q
);
2285 if (!q
->nr_hw_queues
)
2288 INIT_WORK(&q
->timeout_work
, blk_mq_timeout_work
);
2289 blk_queue_rq_timeout(q
, set
->timeout
? set
->timeout
: 30 * HZ
);
2291 q
->nr_queues
= nr_cpu_ids
;
2293 q
->queue_flags
|= QUEUE_FLAG_MQ_DEFAULT
;
2295 if (!(set
->flags
& BLK_MQ_F_SG_MERGE
))
2296 q
->queue_flags
|= 1 << QUEUE_FLAG_NO_SG_MERGE
;
2298 q
->sg_reserved_size
= INT_MAX
;
2300 INIT_DELAYED_WORK(&q
->requeue_work
, blk_mq_requeue_work
);
2301 INIT_LIST_HEAD(&q
->requeue_list
);
2302 spin_lock_init(&q
->requeue_lock
);
2304 blk_queue_make_request(q
, blk_mq_make_request
);
2307 * Do this after blk_queue_make_request() overrides it...
2309 q
->nr_requests
= set
->queue_depth
;
2312 * Default to classic polling
2316 if (set
->ops
->complete
)
2317 blk_queue_softirq_done(q
, set
->ops
->complete
);
2319 blk_mq_init_cpu_queues(q
, set
->nr_hw_queues
);
2322 mutex_lock(&all_q_mutex
);
2324 list_add_tail(&q
->all_q_node
, &all_q_list
);
2325 blk_mq_add_queue_tag_set(set
, q
);
2326 blk_mq_map_swqueue(q
, cpu_online_mask
);
2328 mutex_unlock(&all_q_mutex
);
2331 if (!(set
->flags
& BLK_MQ_F_NO_SCHED
)) {
2334 ret
= blk_mq_sched_init(q
);
2336 return ERR_PTR(ret
);
2342 kfree(q
->queue_hw_ctx
);
2344 free_percpu(q
->queue_ctx
);
2347 return ERR_PTR(-ENOMEM
);
2349 EXPORT_SYMBOL(blk_mq_init_allocated_queue
);
2351 void blk_mq_free_queue(struct request_queue
*q
)
2353 struct blk_mq_tag_set
*set
= q
->tag_set
;
2355 mutex_lock(&all_q_mutex
);
2356 list_del_init(&q
->all_q_node
);
2357 mutex_unlock(&all_q_mutex
);
2359 blk_mq_del_queue_tag_set(q
);
2361 blk_mq_exit_hw_queues(q
, set
, set
->nr_hw_queues
);
2364 /* Basically redo blk_mq_init_queue with queue frozen */
2365 static void blk_mq_queue_reinit(struct request_queue
*q
,
2366 const struct cpumask
*online_mask
)
2368 WARN_ON_ONCE(!atomic_read(&q
->mq_freeze_depth
));
2370 blk_mq_debugfs_unregister_hctxs(q
);
2371 blk_mq_sysfs_unregister(q
);
2374 * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
2375 * we should change hctx numa_node according to new topology (this
2376 * involves free and re-allocate memory, worthy doing?)
2379 blk_mq_map_swqueue(q
, online_mask
);
2381 blk_mq_sysfs_register(q
);
2382 blk_mq_debugfs_register_hctxs(q
);
2386 * New online cpumask which is going to be set in this hotplug event.
2387 * Declare this cpumasks as global as cpu-hotplug operation is invoked
2388 * one-by-one and dynamically allocating this could result in a failure.
2390 static struct cpumask cpuhp_online_new
;
2392 static void blk_mq_queue_reinit_work(void)
2394 struct request_queue
*q
;
2396 mutex_lock(&all_q_mutex
);
2398 * We need to freeze and reinit all existing queues. Freezing
2399 * involves synchronous wait for an RCU grace period and doing it
2400 * one by one may take a long time. Start freezing all queues in
2401 * one swoop and then wait for the completions so that freezing can
2402 * take place in parallel.
2404 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2405 blk_freeze_queue_start(q
);
2406 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2407 blk_mq_freeze_queue_wait(q
);
2409 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2410 blk_mq_queue_reinit(q
, &cpuhp_online_new
);
2412 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2413 blk_mq_unfreeze_queue(q
);
2415 mutex_unlock(&all_q_mutex
);
2418 static int blk_mq_queue_reinit_dead(unsigned int cpu
)
2420 cpumask_copy(&cpuhp_online_new
, cpu_online_mask
);
2421 blk_mq_queue_reinit_work();
2426 * Before hotadded cpu starts handling requests, new mappings must be
2427 * established. Otherwise, these requests in hw queue might never be
2430 * For example, there is a single hw queue (hctx) and two CPU queues (ctx0
2431 * for CPU0, and ctx1 for CPU1).
2433 * Now CPU1 is just onlined and a request is inserted into ctx1->rq_list
2434 * and set bit0 in pending bitmap as ctx1->index_hw is still zero.
2436 * And then while running hw queue, blk_mq_flush_busy_ctxs() finds bit0 is set
2437 * in pending bitmap and tries to retrieve requests in hctx->ctxs[0]->rq_list.
2438 * But htx->ctxs[0] is a pointer to ctx0, so the request in ctx1->rq_list is
2441 static int blk_mq_queue_reinit_prepare(unsigned int cpu
)
2443 cpumask_copy(&cpuhp_online_new
, cpu_online_mask
);
2444 cpumask_set_cpu(cpu
, &cpuhp_online_new
);
2445 blk_mq_queue_reinit_work();
2449 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2453 for (i
= 0; i
< set
->nr_hw_queues
; i
++)
2454 if (!__blk_mq_alloc_rq_map(set
, i
))
2461 blk_mq_free_rq_map(set
->tags
[i
]);
2467 * Allocate the request maps associated with this tag_set. Note that this
2468 * may reduce the depth asked for, if memory is tight. set->queue_depth
2469 * will be updated to reflect the allocated depth.
2471 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2476 depth
= set
->queue_depth
;
2478 err
= __blk_mq_alloc_rq_maps(set
);
2482 set
->queue_depth
>>= 1;
2483 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
) {
2487 } while (set
->queue_depth
);
2489 if (!set
->queue_depth
|| err
) {
2490 pr_err("blk-mq: failed to allocate request map\n");
2494 if (depth
!= set
->queue_depth
)
2495 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2496 depth
, set
->queue_depth
);
2501 static int blk_mq_update_queue_map(struct blk_mq_tag_set
*set
)
2503 if (set
->ops
->map_queues
)
2504 return set
->ops
->map_queues(set
);
2506 return blk_mq_map_queues(set
);
2510 * Alloc a tag set to be associated with one or more request queues.
2511 * May fail with EINVAL for various error conditions. May adjust the
2512 * requested depth down, if if it too large. In that case, the set
2513 * value will be stored in set->queue_depth.
2515 int blk_mq_alloc_tag_set(struct blk_mq_tag_set
*set
)
2519 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH
> 1 << BLK_MQ_UNIQUE_TAG_BITS
);
2521 if (!set
->nr_hw_queues
)
2523 if (!set
->queue_depth
)
2525 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
)
2528 if (!set
->ops
->queue_rq
)
2531 if (set
->queue_depth
> BLK_MQ_MAX_DEPTH
) {
2532 pr_info("blk-mq: reduced tag depth to %u\n",
2534 set
->queue_depth
= BLK_MQ_MAX_DEPTH
;
2538 * If a crashdump is active, then we are potentially in a very
2539 * memory constrained environment. Limit us to 1 queue and
2540 * 64 tags to prevent using too much memory.
2542 if (is_kdump_kernel()) {
2543 set
->nr_hw_queues
= 1;
2544 set
->queue_depth
= min(64U, set
->queue_depth
);
2547 * There is no use for more h/w queues than cpus.
2549 if (set
->nr_hw_queues
> nr_cpu_ids
)
2550 set
->nr_hw_queues
= nr_cpu_ids
;
2552 set
->tags
= kzalloc_node(nr_cpu_ids
* sizeof(struct blk_mq_tags
*),
2553 GFP_KERNEL
, set
->numa_node
);
2558 set
->mq_map
= kzalloc_node(sizeof(*set
->mq_map
) * nr_cpu_ids
,
2559 GFP_KERNEL
, set
->numa_node
);
2563 ret
= blk_mq_update_queue_map(set
);
2565 goto out_free_mq_map
;
2567 ret
= blk_mq_alloc_rq_maps(set
);
2569 goto out_free_mq_map
;
2571 mutex_init(&set
->tag_list_lock
);
2572 INIT_LIST_HEAD(&set
->tag_list
);
2584 EXPORT_SYMBOL(blk_mq_alloc_tag_set
);
2586 void blk_mq_free_tag_set(struct blk_mq_tag_set
*set
)
2590 for (i
= 0; i
< nr_cpu_ids
; i
++)
2591 blk_mq_free_map_and_requests(set
, i
);
2599 EXPORT_SYMBOL(blk_mq_free_tag_set
);
2601 int blk_mq_update_nr_requests(struct request_queue
*q
, unsigned int nr
)
2603 struct blk_mq_tag_set
*set
= q
->tag_set
;
2604 struct blk_mq_hw_ctx
*hctx
;
2610 blk_mq_freeze_queue(q
);
2613 queue_for_each_hw_ctx(q
, hctx
, i
) {
2617 * If we're using an MQ scheduler, just update the scheduler
2618 * queue depth. This is similar to what the old code would do.
2620 if (!hctx
->sched_tags
) {
2621 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->tags
,
2622 min(nr
, set
->queue_depth
),
2625 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->sched_tags
,
2633 q
->nr_requests
= nr
;
2635 blk_mq_unfreeze_queue(q
);
2640 static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
,
2643 struct request_queue
*q
;
2645 lockdep_assert_held(&set
->tag_list_lock
);
2647 if (nr_hw_queues
> nr_cpu_ids
)
2648 nr_hw_queues
= nr_cpu_ids
;
2649 if (nr_hw_queues
< 1 || nr_hw_queues
== set
->nr_hw_queues
)
2652 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
2653 blk_mq_freeze_queue(q
);
2655 set
->nr_hw_queues
= nr_hw_queues
;
2656 blk_mq_update_queue_map(set
);
2657 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
2658 blk_mq_realloc_hw_ctxs(set
, q
);
2659 blk_mq_queue_reinit(q
, cpu_online_mask
);
2662 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
2663 blk_mq_unfreeze_queue(q
);
2666 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
, int nr_hw_queues
)
2668 mutex_lock(&set
->tag_list_lock
);
2669 __blk_mq_update_nr_hw_queues(set
, nr_hw_queues
);
2670 mutex_unlock(&set
->tag_list_lock
);
2672 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues
);
2674 /* Enable polling stats and return whether they were already enabled. */
2675 static bool blk_poll_stats_enable(struct request_queue
*q
)
2677 if (test_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
) ||
2678 test_and_set_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
))
2680 blk_stat_add_callback(q
, q
->poll_cb
);
2684 static void blk_mq_poll_stats_start(struct request_queue
*q
)
2687 * We don't arm the callback if polling stats are not enabled or the
2688 * callback is already active.
2690 if (!test_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
) ||
2691 blk_stat_is_active(q
->poll_cb
))
2694 blk_stat_activate_msecs(q
->poll_cb
, 100);
2697 static void blk_mq_poll_stats_fn(struct blk_stat_callback
*cb
)
2699 struct request_queue
*q
= cb
->data
;
2702 for (bucket
= 0; bucket
< BLK_MQ_POLL_STATS_BKTS
; bucket
++) {
2703 if (cb
->stat
[bucket
].nr_samples
)
2704 q
->poll_stat
[bucket
] = cb
->stat
[bucket
];
2708 static unsigned long blk_mq_poll_nsecs(struct request_queue
*q
,
2709 struct blk_mq_hw_ctx
*hctx
,
2712 unsigned long ret
= 0;
2716 * If stats collection isn't on, don't sleep but turn it on for
2719 if (!blk_poll_stats_enable(q
))
2723 * As an optimistic guess, use half of the mean service time
2724 * for this type of request. We can (and should) make this smarter.
2725 * For instance, if the completion latencies are tight, we can
2726 * get closer than just half the mean. This is especially
2727 * important on devices where the completion latencies are longer
2728 * than ~10 usec. We do use the stats for the relevant IO size
2729 * if available which does lead to better estimates.
2731 bucket
= blk_mq_poll_stats_bkt(rq
);
2735 if (q
->poll_stat
[bucket
].nr_samples
)
2736 ret
= (q
->poll_stat
[bucket
].mean
+ 1) / 2;
2741 static bool blk_mq_poll_hybrid_sleep(struct request_queue
*q
,
2742 struct blk_mq_hw_ctx
*hctx
,
2745 struct hrtimer_sleeper hs
;
2746 enum hrtimer_mode mode
;
2750 if (test_bit(REQ_ATOM_POLL_SLEPT
, &rq
->atomic_flags
))
2756 * -1: don't ever hybrid sleep
2757 * 0: use half of prev avg
2758 * >0: use this specific value
2760 if (q
->poll_nsec
== -1)
2762 else if (q
->poll_nsec
> 0)
2763 nsecs
= q
->poll_nsec
;
2765 nsecs
= blk_mq_poll_nsecs(q
, hctx
, rq
);
2770 set_bit(REQ_ATOM_POLL_SLEPT
, &rq
->atomic_flags
);
2773 * This will be replaced with the stats tracking code, using
2774 * 'avg_completion_time / 2' as the pre-sleep target.
2778 mode
= HRTIMER_MODE_REL
;
2779 hrtimer_init_on_stack(&hs
.timer
, CLOCK_MONOTONIC
, mode
);
2780 hrtimer_set_expires(&hs
.timer
, kt
);
2782 hrtimer_init_sleeper(&hs
, current
);
2784 if (test_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
))
2786 set_current_state(TASK_UNINTERRUPTIBLE
);
2787 hrtimer_start_expires(&hs
.timer
, mode
);
2790 hrtimer_cancel(&hs
.timer
);
2791 mode
= HRTIMER_MODE_ABS
;
2792 } while (hs
.task
&& !signal_pending(current
));
2794 __set_current_state(TASK_RUNNING
);
2795 destroy_hrtimer_on_stack(&hs
.timer
);
2799 static bool __blk_mq_poll(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
)
2801 struct request_queue
*q
= hctx
->queue
;
2805 * If we sleep, have the caller restart the poll loop to reset
2806 * the state. Like for the other success return cases, the
2807 * caller is responsible for checking if the IO completed. If
2808 * the IO isn't complete, we'll get called again and will go
2809 * straight to the busy poll loop.
2811 if (blk_mq_poll_hybrid_sleep(q
, hctx
, rq
))
2814 hctx
->poll_considered
++;
2816 state
= current
->state
;
2817 while (!need_resched()) {
2820 hctx
->poll_invoked
++;
2822 ret
= q
->mq_ops
->poll(hctx
, rq
->tag
);
2824 hctx
->poll_success
++;
2825 set_current_state(TASK_RUNNING
);
2829 if (signal_pending_state(state
, current
))
2830 set_current_state(TASK_RUNNING
);
2832 if (current
->state
== TASK_RUNNING
)
2842 bool blk_mq_poll(struct request_queue
*q
, blk_qc_t cookie
)
2844 struct blk_mq_hw_ctx
*hctx
;
2845 struct blk_plug
*plug
;
2848 if (!q
->mq_ops
|| !q
->mq_ops
->poll
|| !blk_qc_t_valid(cookie
) ||
2849 !test_bit(QUEUE_FLAG_POLL
, &q
->queue_flags
))
2852 plug
= current
->plug
;
2854 blk_flush_plug_list(plug
, false);
2856 hctx
= q
->queue_hw_ctx
[blk_qc_t_to_queue_num(cookie
)];
2857 if (!blk_qc_t_is_internal(cookie
))
2858 rq
= blk_mq_tag_to_rq(hctx
->tags
, blk_qc_t_to_tag(cookie
));
2860 rq
= blk_mq_tag_to_rq(hctx
->sched_tags
, blk_qc_t_to_tag(cookie
));
2862 * With scheduling, if the request has completed, we'll
2863 * get a NULL return here, as we clear the sched tag when
2864 * that happens. The request still remains valid, like always,
2865 * so we should be safe with just the NULL check.
2871 return __blk_mq_poll(hctx
, rq
);
2873 EXPORT_SYMBOL_GPL(blk_mq_poll
);
2875 void blk_mq_disable_hotplug(void)
2877 mutex_lock(&all_q_mutex
);
2880 void blk_mq_enable_hotplug(void)
2882 mutex_unlock(&all_q_mutex
);
2885 static int __init
blk_mq_init(void)
2887 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD
, "block/mq:dead", NULL
,
2888 blk_mq_hctx_notify_dead
);
2890 cpuhp_setup_state_nocalls(CPUHP_BLK_MQ_PREPARE
, "block/mq:prepare",
2891 blk_mq_queue_reinit_prepare
,
2892 blk_mq_queue_reinit_dead
);
2895 subsys_initcall(blk_mq_init
);