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
);
298 data
->flags
|= BLK_MQ_REQ_INTERNAL
;
301 * Flush requests are special and go directly to the
304 if (!op_is_flush(op
) && e
->type
->ops
.mq
.limit_depth
)
305 e
->type
->ops
.mq
.limit_depth(op
, data
);
308 tag
= blk_mq_get_tag(data
);
309 if (tag
== BLK_MQ_TAG_FAIL
) {
314 rq
= blk_mq_rq_ctx_init(data
, tag
, op
);
315 if (!op_is_flush(op
)) {
317 if (e
&& e
->type
->ops
.mq
.prepare_request
) {
318 if (e
->type
->icq_cache
&& rq_ioc(bio
))
319 blk_mq_sched_assign_ioc(rq
, bio
);
321 e
->type
->ops
.mq
.prepare_request(rq
, bio
);
322 rq
->rq_flags
|= RQF_ELVPRIV
;
325 data
->hctx
->queued
++;
329 struct request
*blk_mq_alloc_request(struct request_queue
*q
, int rw
,
332 struct blk_mq_alloc_data alloc_data
= { .flags
= flags
};
336 ret
= blk_queue_enter(q
, flags
& BLK_MQ_REQ_NOWAIT
);
340 rq
= blk_mq_get_request(q
, NULL
, rw
, &alloc_data
);
342 blk_mq_put_ctx(alloc_data
.ctx
);
346 return ERR_PTR(-EWOULDBLOCK
);
349 rq
->__sector
= (sector_t
) -1;
350 rq
->bio
= rq
->biotail
= NULL
;
353 EXPORT_SYMBOL(blk_mq_alloc_request
);
355 struct request
*blk_mq_alloc_request_hctx(struct request_queue
*q
, int rw
,
356 unsigned int flags
, unsigned int hctx_idx
)
358 struct blk_mq_alloc_data alloc_data
= { .flags
= flags
};
364 * If the tag allocator sleeps we could get an allocation for a
365 * different hardware context. No need to complicate the low level
366 * allocator for this for the rare use case of a command tied to
369 if (WARN_ON_ONCE(!(flags
& BLK_MQ_REQ_NOWAIT
)))
370 return ERR_PTR(-EINVAL
);
372 if (hctx_idx
>= q
->nr_hw_queues
)
373 return ERR_PTR(-EIO
);
375 ret
= blk_queue_enter(q
, true);
380 * Check if the hardware context is actually mapped to anything.
381 * If not tell the caller that it should skip this queue.
383 alloc_data
.hctx
= q
->queue_hw_ctx
[hctx_idx
];
384 if (!blk_mq_hw_queue_mapped(alloc_data
.hctx
)) {
386 return ERR_PTR(-EXDEV
);
388 cpu
= cpumask_first(alloc_data
.hctx
->cpumask
);
389 alloc_data
.ctx
= __blk_mq_get_ctx(q
, cpu
);
391 rq
= blk_mq_get_request(q
, NULL
, rw
, &alloc_data
);
396 return ERR_PTR(-EWOULDBLOCK
);
400 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx
);
402 void blk_mq_free_request(struct request
*rq
)
404 struct request_queue
*q
= rq
->q
;
405 struct elevator_queue
*e
= q
->elevator
;
406 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
407 struct blk_mq_hw_ctx
*hctx
= blk_mq_map_queue(q
, ctx
->cpu
);
408 const int sched_tag
= rq
->internal_tag
;
410 if (rq
->rq_flags
& RQF_ELVPRIV
) {
411 if (e
&& e
->type
->ops
.mq
.finish_request
)
412 e
->type
->ops
.mq
.finish_request(rq
);
414 put_io_context(rq
->elv
.icq
->ioc
);
419 ctx
->rq_completed
[rq_is_sync(rq
)]++;
420 if (rq
->rq_flags
& RQF_MQ_INFLIGHT
)
421 atomic_dec(&hctx
->nr_active
);
423 wbt_done(q
->rq_wb
, &rq
->issue_stat
);
426 clear_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
427 clear_bit(REQ_ATOM_POLL_SLEPT
, &rq
->atomic_flags
);
429 blk_mq_put_tag(hctx
, hctx
->tags
, ctx
, rq
->tag
);
431 blk_mq_put_tag(hctx
, hctx
->sched_tags
, ctx
, sched_tag
);
432 blk_mq_sched_restart(hctx
);
435 EXPORT_SYMBOL_GPL(blk_mq_free_request
);
437 inline void __blk_mq_end_request(struct request
*rq
, blk_status_t error
)
439 blk_account_io_done(rq
);
442 wbt_done(rq
->q
->rq_wb
, &rq
->issue_stat
);
443 rq
->end_io(rq
, error
);
445 if (unlikely(blk_bidi_rq(rq
)))
446 blk_mq_free_request(rq
->next_rq
);
447 blk_mq_free_request(rq
);
450 EXPORT_SYMBOL(__blk_mq_end_request
);
452 void blk_mq_end_request(struct request
*rq
, blk_status_t error
)
454 if (blk_update_request(rq
, error
, blk_rq_bytes(rq
)))
456 __blk_mq_end_request(rq
, error
);
458 EXPORT_SYMBOL(blk_mq_end_request
);
460 static void __blk_mq_complete_request_remote(void *data
)
462 struct request
*rq
= data
;
464 rq
->q
->softirq_done_fn(rq
);
467 static void __blk_mq_complete_request(struct request
*rq
)
469 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
473 if (rq
->internal_tag
!= -1)
474 blk_mq_sched_completed_request(rq
);
475 if (rq
->rq_flags
& RQF_STATS
) {
476 blk_mq_poll_stats_start(rq
->q
);
480 if (!test_bit(QUEUE_FLAG_SAME_COMP
, &rq
->q
->queue_flags
)) {
481 rq
->q
->softirq_done_fn(rq
);
486 if (!test_bit(QUEUE_FLAG_SAME_FORCE
, &rq
->q
->queue_flags
))
487 shared
= cpus_share_cache(cpu
, ctx
->cpu
);
489 if (cpu
!= ctx
->cpu
&& !shared
&& cpu_online(ctx
->cpu
)) {
490 rq
->csd
.func
= __blk_mq_complete_request_remote
;
493 smp_call_function_single_async(ctx
->cpu
, &rq
->csd
);
495 rq
->q
->softirq_done_fn(rq
);
501 * blk_mq_complete_request - end I/O on a request
502 * @rq: the request being processed
505 * Ends all I/O on a request. It does not handle partial completions.
506 * The actual completion happens out-of-order, through a IPI handler.
508 void blk_mq_complete_request(struct request
*rq
)
510 struct request_queue
*q
= rq
->q
;
512 if (unlikely(blk_should_fake_timeout(q
)))
514 if (!blk_mark_rq_complete(rq
))
515 __blk_mq_complete_request(rq
);
517 EXPORT_SYMBOL(blk_mq_complete_request
);
519 int blk_mq_request_started(struct request
*rq
)
521 return test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
523 EXPORT_SYMBOL_GPL(blk_mq_request_started
);
525 void blk_mq_start_request(struct request
*rq
)
527 struct request_queue
*q
= rq
->q
;
529 blk_mq_sched_started_request(rq
);
531 trace_block_rq_issue(q
, rq
);
533 if (test_bit(QUEUE_FLAG_STATS
, &q
->queue_flags
)) {
534 blk_stat_set_issue(&rq
->issue_stat
, blk_rq_sectors(rq
));
535 rq
->rq_flags
|= RQF_STATS
;
536 wbt_issue(q
->rq_wb
, &rq
->issue_stat
);
542 * Ensure that ->deadline is visible before set the started
543 * flag and clear the completed flag.
545 smp_mb__before_atomic();
548 * Mark us as started and clear complete. Complete might have been
549 * set if requeue raced with timeout, which then marked it as
550 * complete. So be sure to clear complete again when we start
551 * the request, otherwise we'll ignore the completion event.
553 if (!test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
))
554 set_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
555 if (test_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
))
556 clear_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
);
558 if (q
->dma_drain_size
&& blk_rq_bytes(rq
)) {
560 * Make sure space for the drain appears. We know we can do
561 * this because max_hw_segments has been adjusted to be one
562 * fewer than the device can handle.
564 rq
->nr_phys_segments
++;
567 EXPORT_SYMBOL(blk_mq_start_request
);
570 * When we reach here because queue is busy, REQ_ATOM_COMPLETE
571 * flag isn't set yet, so there may be race with timeout handler,
572 * but given rq->deadline is just set in .queue_rq() under
573 * this situation, the race won't be possible in reality because
574 * rq->timeout should be set as big enough to cover the window
575 * between blk_mq_start_request() called from .queue_rq() and
576 * clearing REQ_ATOM_STARTED here.
578 static void __blk_mq_requeue_request(struct request
*rq
)
580 struct request_queue
*q
= rq
->q
;
582 trace_block_rq_requeue(q
, rq
);
583 wbt_requeue(q
->rq_wb
, &rq
->issue_stat
);
584 blk_mq_sched_requeue_request(rq
);
586 if (test_and_clear_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
)) {
587 if (q
->dma_drain_size
&& blk_rq_bytes(rq
))
588 rq
->nr_phys_segments
--;
592 void blk_mq_requeue_request(struct request
*rq
, bool kick_requeue_list
)
594 __blk_mq_requeue_request(rq
);
596 BUG_ON(blk_queued_rq(rq
));
597 blk_mq_add_to_requeue_list(rq
, true, kick_requeue_list
);
599 EXPORT_SYMBOL(blk_mq_requeue_request
);
601 static void blk_mq_requeue_work(struct work_struct
*work
)
603 struct request_queue
*q
=
604 container_of(work
, struct request_queue
, requeue_work
.work
);
606 struct request
*rq
, *next
;
609 spin_lock_irqsave(&q
->requeue_lock
, flags
);
610 list_splice_init(&q
->requeue_list
, &rq_list
);
611 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
613 list_for_each_entry_safe(rq
, next
, &rq_list
, queuelist
) {
614 if (!(rq
->rq_flags
& RQF_SOFTBARRIER
))
617 rq
->rq_flags
&= ~RQF_SOFTBARRIER
;
618 list_del_init(&rq
->queuelist
);
619 blk_mq_sched_insert_request(rq
, true, false, false, true);
622 while (!list_empty(&rq_list
)) {
623 rq
= list_entry(rq_list
.next
, struct request
, queuelist
);
624 list_del_init(&rq
->queuelist
);
625 blk_mq_sched_insert_request(rq
, false, false, false, true);
628 blk_mq_run_hw_queues(q
, false);
631 void blk_mq_add_to_requeue_list(struct request
*rq
, bool at_head
,
632 bool kick_requeue_list
)
634 struct request_queue
*q
= rq
->q
;
638 * We abuse this flag that is otherwise used by the I/O scheduler to
639 * request head insertation from the workqueue.
641 BUG_ON(rq
->rq_flags
& RQF_SOFTBARRIER
);
643 spin_lock_irqsave(&q
->requeue_lock
, flags
);
645 rq
->rq_flags
|= RQF_SOFTBARRIER
;
646 list_add(&rq
->queuelist
, &q
->requeue_list
);
648 list_add_tail(&rq
->queuelist
, &q
->requeue_list
);
650 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
652 if (kick_requeue_list
)
653 blk_mq_kick_requeue_list(q
);
655 EXPORT_SYMBOL(blk_mq_add_to_requeue_list
);
657 void blk_mq_kick_requeue_list(struct request_queue
*q
)
659 kblockd_schedule_delayed_work(&q
->requeue_work
, 0);
661 EXPORT_SYMBOL(blk_mq_kick_requeue_list
);
663 void blk_mq_delay_kick_requeue_list(struct request_queue
*q
,
666 kblockd_schedule_delayed_work(&q
->requeue_work
,
667 msecs_to_jiffies(msecs
));
669 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list
);
671 struct request
*blk_mq_tag_to_rq(struct blk_mq_tags
*tags
, unsigned int tag
)
673 if (tag
< tags
->nr_tags
) {
674 prefetch(tags
->rqs
[tag
]);
675 return tags
->rqs
[tag
];
680 EXPORT_SYMBOL(blk_mq_tag_to_rq
);
682 struct blk_mq_timeout_data
{
684 unsigned int next_set
;
687 void blk_mq_rq_timed_out(struct request
*req
, bool reserved
)
689 const struct blk_mq_ops
*ops
= req
->q
->mq_ops
;
690 enum blk_eh_timer_return ret
= BLK_EH_RESET_TIMER
;
693 * We know that complete is set at this point. If STARTED isn't set
694 * anymore, then the request isn't active and the "timeout" should
695 * just be ignored. This can happen due to the bitflag ordering.
696 * Timeout first checks if STARTED is set, and if it is, assumes
697 * the request is active. But if we race with completion, then
698 * both flags will get cleared. So check here again, and ignore
699 * a timeout event with a request that isn't active.
701 if (!test_bit(REQ_ATOM_STARTED
, &req
->atomic_flags
))
705 ret
= ops
->timeout(req
, reserved
);
709 __blk_mq_complete_request(req
);
711 case BLK_EH_RESET_TIMER
:
713 blk_clear_rq_complete(req
);
715 case BLK_EH_NOT_HANDLED
:
718 printk(KERN_ERR
"block: bad eh return: %d\n", ret
);
723 static void blk_mq_check_expired(struct blk_mq_hw_ctx
*hctx
,
724 struct request
*rq
, void *priv
, bool reserved
)
726 struct blk_mq_timeout_data
*data
= priv
;
728 if (!test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
))
732 * The rq being checked may have been freed and reallocated
733 * out already here, we avoid this race by checking rq->deadline
734 * and REQ_ATOM_COMPLETE flag together:
736 * - if rq->deadline is observed as new value because of
737 * reusing, the rq won't be timed out because of timing.
738 * - if rq->deadline is observed as previous value,
739 * REQ_ATOM_COMPLETE flag won't be cleared in reuse path
740 * because we put a barrier between setting rq->deadline
741 * and clearing the flag in blk_mq_start_request(), so
742 * this rq won't be timed out too.
744 if (time_after_eq(jiffies
, rq
->deadline
)) {
745 if (!blk_mark_rq_complete(rq
))
746 blk_mq_rq_timed_out(rq
, reserved
);
747 } else if (!data
->next_set
|| time_after(data
->next
, rq
->deadline
)) {
748 data
->next
= rq
->deadline
;
753 static void blk_mq_timeout_work(struct work_struct
*work
)
755 struct request_queue
*q
=
756 container_of(work
, struct request_queue
, timeout_work
);
757 struct blk_mq_timeout_data data
= {
763 /* A deadlock might occur if a request is stuck requiring a
764 * timeout at the same time a queue freeze is waiting
765 * completion, since the timeout code would not be able to
766 * acquire the queue reference here.
768 * That's why we don't use blk_queue_enter here; instead, we use
769 * percpu_ref_tryget directly, because we need to be able to
770 * obtain a reference even in the short window between the queue
771 * starting to freeze, by dropping the first reference in
772 * blk_freeze_queue_start, and the moment the last request is
773 * consumed, marked by the instant q_usage_counter reaches
776 if (!percpu_ref_tryget(&q
->q_usage_counter
))
779 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_expired
, &data
);
782 data
.next
= blk_rq_timeout(round_jiffies_up(data
.next
));
783 mod_timer(&q
->timeout
, data
.next
);
785 struct blk_mq_hw_ctx
*hctx
;
787 queue_for_each_hw_ctx(q
, hctx
, i
) {
788 /* the hctx may be unmapped, so check it here */
789 if (blk_mq_hw_queue_mapped(hctx
))
790 blk_mq_tag_idle(hctx
);
796 struct flush_busy_ctx_data
{
797 struct blk_mq_hw_ctx
*hctx
;
798 struct list_head
*list
;
801 static bool flush_busy_ctx(struct sbitmap
*sb
, unsigned int bitnr
, void *data
)
803 struct flush_busy_ctx_data
*flush_data
= data
;
804 struct blk_mq_hw_ctx
*hctx
= flush_data
->hctx
;
805 struct blk_mq_ctx
*ctx
= hctx
->ctxs
[bitnr
];
807 sbitmap_clear_bit(sb
, bitnr
);
808 spin_lock(&ctx
->lock
);
809 list_splice_tail_init(&ctx
->rq_list
, flush_data
->list
);
810 spin_unlock(&ctx
->lock
);
815 * Process software queues that have been marked busy, splicing them
816 * to the for-dispatch
818 void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx
*hctx
, struct list_head
*list
)
820 struct flush_busy_ctx_data data
= {
825 sbitmap_for_each_set(&hctx
->ctx_map
, flush_busy_ctx
, &data
);
827 EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs
);
829 static inline unsigned int queued_to_index(unsigned int queued
)
834 return min(BLK_MQ_MAX_DISPATCH_ORDER
- 1, ilog2(queued
) + 1);
837 bool blk_mq_get_driver_tag(struct request
*rq
, struct blk_mq_hw_ctx
**hctx
,
840 struct blk_mq_alloc_data data
= {
842 .hctx
= blk_mq_map_queue(rq
->q
, rq
->mq_ctx
->cpu
),
843 .flags
= wait
? 0 : BLK_MQ_REQ_NOWAIT
,
846 might_sleep_if(wait
);
851 if (blk_mq_tag_is_reserved(data
.hctx
->sched_tags
, rq
->internal_tag
))
852 data
.flags
|= BLK_MQ_REQ_RESERVED
;
854 rq
->tag
= blk_mq_get_tag(&data
);
856 if (blk_mq_tag_busy(data
.hctx
)) {
857 rq
->rq_flags
|= RQF_MQ_INFLIGHT
;
858 atomic_inc(&data
.hctx
->nr_active
);
860 data
.hctx
->tags
->rqs
[rq
->tag
] = rq
;
866 return rq
->tag
!= -1;
869 static void __blk_mq_put_driver_tag(struct blk_mq_hw_ctx
*hctx
,
872 blk_mq_put_tag(hctx
, hctx
->tags
, rq
->mq_ctx
, rq
->tag
);
875 if (rq
->rq_flags
& RQF_MQ_INFLIGHT
) {
876 rq
->rq_flags
&= ~RQF_MQ_INFLIGHT
;
877 atomic_dec(&hctx
->nr_active
);
881 static void blk_mq_put_driver_tag_hctx(struct blk_mq_hw_ctx
*hctx
,
884 if (rq
->tag
== -1 || rq
->internal_tag
== -1)
887 __blk_mq_put_driver_tag(hctx
, rq
);
890 static void blk_mq_put_driver_tag(struct request
*rq
)
892 struct blk_mq_hw_ctx
*hctx
;
894 if (rq
->tag
== -1 || rq
->internal_tag
== -1)
897 hctx
= blk_mq_map_queue(rq
->q
, rq
->mq_ctx
->cpu
);
898 __blk_mq_put_driver_tag(hctx
, rq
);
902 * If we fail getting a driver tag because all the driver tags are already
903 * assigned and on the dispatch list, BUT the first entry does not have a
904 * tag, then we could deadlock. For that case, move entries with assigned
905 * driver tags to the front, leaving the set of tagged requests in the
906 * same order, and the untagged set in the same order.
908 static bool reorder_tags_to_front(struct list_head
*list
)
910 struct request
*rq
, *tmp
, *first
= NULL
;
912 list_for_each_entry_safe_reverse(rq
, tmp
, list
, queuelist
) {
916 list_move(&rq
->queuelist
, list
);
922 return first
!= NULL
;
925 static int blk_mq_dispatch_wake(wait_queue_t
*wait
, unsigned mode
, int flags
,
928 struct blk_mq_hw_ctx
*hctx
;
930 hctx
= container_of(wait
, struct blk_mq_hw_ctx
, dispatch_wait
);
932 list_del(&wait
->task_list
);
933 clear_bit_unlock(BLK_MQ_S_TAG_WAITING
, &hctx
->state
);
934 blk_mq_run_hw_queue(hctx
, true);
938 static bool blk_mq_dispatch_wait_add(struct blk_mq_hw_ctx
*hctx
)
940 struct sbq_wait_state
*ws
;
943 * The TAG_WAITING bit serves as a lock protecting hctx->dispatch_wait.
944 * The thread which wins the race to grab this bit adds the hardware
945 * queue to the wait queue.
947 if (test_bit(BLK_MQ_S_TAG_WAITING
, &hctx
->state
) ||
948 test_and_set_bit_lock(BLK_MQ_S_TAG_WAITING
, &hctx
->state
))
951 init_waitqueue_func_entry(&hctx
->dispatch_wait
, blk_mq_dispatch_wake
);
952 ws
= bt_wait_ptr(&hctx
->tags
->bitmap_tags
, hctx
);
955 * As soon as this returns, it's no longer safe to fiddle with
956 * hctx->dispatch_wait, since a completion can wake up the wait queue
957 * and unlock the bit.
959 add_wait_queue(&ws
->wait
, &hctx
->dispatch_wait
);
963 bool blk_mq_dispatch_rq_list(struct request_queue
*q
, struct list_head
*list
)
965 struct blk_mq_hw_ctx
*hctx
;
969 if (list_empty(list
))
973 * Now process all the entries, sending them to the driver.
977 struct blk_mq_queue_data bd
;
980 rq
= list_first_entry(list
, struct request
, queuelist
);
981 if (!blk_mq_get_driver_tag(rq
, &hctx
, false)) {
982 if (!queued
&& reorder_tags_to_front(list
))
986 * The initial allocation attempt failed, so we need to
987 * rerun the hardware queue when a tag is freed.
989 if (!blk_mq_dispatch_wait_add(hctx
))
993 * It's possible that a tag was freed in the window
994 * between the allocation failure and adding the
995 * hardware queue to the wait queue.
997 if (!blk_mq_get_driver_tag(rq
, &hctx
, false))
1001 list_del_init(&rq
->queuelist
);
1006 * Flag last if we have no more requests, or if we have more
1007 * but can't assign a driver tag to it.
1009 if (list_empty(list
))
1012 struct request
*nxt
;
1014 nxt
= list_first_entry(list
, struct request
, queuelist
);
1015 bd
.last
= !blk_mq_get_driver_tag(nxt
, NULL
, false);
1018 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1019 if (ret
== BLK_STS_RESOURCE
) {
1020 blk_mq_put_driver_tag_hctx(hctx
, rq
);
1021 list_add(&rq
->queuelist
, list
);
1022 __blk_mq_requeue_request(rq
);
1026 if (unlikely(ret
!= BLK_STS_OK
)) {
1028 blk_mq_end_request(rq
, BLK_STS_IOERR
);
1033 } while (!list_empty(list
));
1035 hctx
->dispatched
[queued_to_index(queued
)]++;
1038 * Any items that need requeuing? Stuff them into hctx->dispatch,
1039 * that is where we will continue on next queue run.
1041 if (!list_empty(list
)) {
1043 * If an I/O scheduler has been configured and we got a driver
1044 * tag for the next request already, free it again.
1046 rq
= list_first_entry(list
, struct request
, queuelist
);
1047 blk_mq_put_driver_tag(rq
);
1049 spin_lock(&hctx
->lock
);
1050 list_splice_init(list
, &hctx
->dispatch
);
1051 spin_unlock(&hctx
->lock
);
1054 * If SCHED_RESTART was set by the caller of this function and
1055 * it is no longer set that means that it was cleared by another
1056 * thread and hence that a queue rerun is needed.
1058 * If TAG_WAITING is set that means that an I/O scheduler has
1059 * been configured and another thread is waiting for a driver
1060 * tag. To guarantee fairness, do not rerun this hardware queue
1061 * but let the other thread grab the driver tag.
1063 * If no I/O scheduler has been configured it is possible that
1064 * the hardware queue got stopped and restarted before requests
1065 * were pushed back onto the dispatch list. Rerun the queue to
1066 * avoid starvation. Notes:
1067 * - blk_mq_run_hw_queue() checks whether or not a queue has
1068 * been stopped before rerunning a queue.
1069 * - Some but not all block drivers stop a queue before
1070 * returning BLK_STS_RESOURCE. Two exceptions are scsi-mq
1073 if (!blk_mq_sched_needs_restart(hctx
) &&
1074 !test_bit(BLK_MQ_S_TAG_WAITING
, &hctx
->state
))
1075 blk_mq_run_hw_queue(hctx
, true);
1078 return (queued
+ errors
) != 0;
1081 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1085 WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx
->cpumask
) &&
1086 cpu_online(hctx
->next_cpu
));
1088 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1090 blk_mq_sched_dispatch_requests(hctx
);
1095 srcu_idx
= srcu_read_lock(&hctx
->queue_rq_srcu
);
1096 blk_mq_sched_dispatch_requests(hctx
);
1097 srcu_read_unlock(&hctx
->queue_rq_srcu
, srcu_idx
);
1102 * It'd be great if the workqueue API had a way to pass
1103 * in a mask and had some smarts for more clever placement.
1104 * For now we just round-robin here, switching for every
1105 * BLK_MQ_CPU_WORK_BATCH queued items.
1107 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx
*hctx
)
1109 if (hctx
->queue
->nr_hw_queues
== 1)
1110 return WORK_CPU_UNBOUND
;
1112 if (--hctx
->next_cpu_batch
<= 0) {
1115 next_cpu
= cpumask_next(hctx
->next_cpu
, hctx
->cpumask
);
1116 if (next_cpu
>= nr_cpu_ids
)
1117 next_cpu
= cpumask_first(hctx
->cpumask
);
1119 hctx
->next_cpu
= next_cpu
;
1120 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
1123 return hctx
->next_cpu
;
1126 static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
,
1127 unsigned long msecs
)
1129 if (unlikely(blk_mq_hctx_stopped(hctx
) ||
1130 !blk_mq_hw_queue_mapped(hctx
)))
1133 if (!async
&& !(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1134 int cpu
= get_cpu();
1135 if (cpumask_test_cpu(cpu
, hctx
->cpumask
)) {
1136 __blk_mq_run_hw_queue(hctx
);
1144 kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx
),
1146 msecs_to_jiffies(msecs
));
1149 void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, unsigned long msecs
)
1151 __blk_mq_delay_run_hw_queue(hctx
, true, msecs
);
1153 EXPORT_SYMBOL(blk_mq_delay_run_hw_queue
);
1155 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1157 __blk_mq_delay_run_hw_queue(hctx
, async
, 0);
1159 EXPORT_SYMBOL(blk_mq_run_hw_queue
);
1161 void blk_mq_run_hw_queues(struct request_queue
*q
, bool async
)
1163 struct blk_mq_hw_ctx
*hctx
;
1166 queue_for_each_hw_ctx(q
, hctx
, i
) {
1167 if (!blk_mq_hctx_has_pending(hctx
) ||
1168 blk_mq_hctx_stopped(hctx
))
1171 blk_mq_run_hw_queue(hctx
, async
);
1174 EXPORT_SYMBOL(blk_mq_run_hw_queues
);
1177 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1178 * @q: request queue.
1180 * The caller is responsible for serializing this function against
1181 * blk_mq_{start,stop}_hw_queue().
1183 bool blk_mq_queue_stopped(struct request_queue
*q
)
1185 struct blk_mq_hw_ctx
*hctx
;
1188 queue_for_each_hw_ctx(q
, hctx
, i
)
1189 if (blk_mq_hctx_stopped(hctx
))
1194 EXPORT_SYMBOL(blk_mq_queue_stopped
);
1197 * This function is often used for pausing .queue_rq() by driver when
1198 * there isn't enough resource or some conditions aren't satisfied, and
1199 * BLK_MQ_RQ_QUEUE_BUSY is usually returned.
1201 * We do not guarantee that dispatch can be drained or blocked
1202 * after blk_mq_stop_hw_queue() returns. Please use
1203 * blk_mq_quiesce_queue() for that requirement.
1205 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1207 cancel_delayed_work(&hctx
->run_work
);
1209 set_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1211 EXPORT_SYMBOL(blk_mq_stop_hw_queue
);
1214 * This function is often used for pausing .queue_rq() by driver when
1215 * there isn't enough resource or some conditions aren't satisfied, and
1216 * BLK_MQ_RQ_QUEUE_BUSY is usually returned.
1218 * We do not guarantee that dispatch can be drained or blocked
1219 * after blk_mq_stop_hw_queues() returns. Please use
1220 * blk_mq_quiesce_queue() for that requirement.
1222 void blk_mq_stop_hw_queues(struct request_queue
*q
)
1224 struct blk_mq_hw_ctx
*hctx
;
1227 queue_for_each_hw_ctx(q
, hctx
, i
)
1228 blk_mq_stop_hw_queue(hctx
);
1230 EXPORT_SYMBOL(blk_mq_stop_hw_queues
);
1232 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1234 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1236 blk_mq_run_hw_queue(hctx
, false);
1238 EXPORT_SYMBOL(blk_mq_start_hw_queue
);
1240 void blk_mq_start_hw_queues(struct request_queue
*q
)
1242 struct blk_mq_hw_ctx
*hctx
;
1245 queue_for_each_hw_ctx(q
, hctx
, i
)
1246 blk_mq_start_hw_queue(hctx
);
1248 EXPORT_SYMBOL(blk_mq_start_hw_queues
);
1250 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1252 if (!blk_mq_hctx_stopped(hctx
))
1255 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1256 blk_mq_run_hw_queue(hctx
, async
);
1258 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue
);
1260 void blk_mq_start_stopped_hw_queues(struct request_queue
*q
, bool async
)
1262 struct blk_mq_hw_ctx
*hctx
;
1265 queue_for_each_hw_ctx(q
, hctx
, i
)
1266 blk_mq_start_stopped_hw_queue(hctx
, async
);
1268 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues
);
1270 static void blk_mq_run_work_fn(struct work_struct
*work
)
1272 struct blk_mq_hw_ctx
*hctx
;
1274 hctx
= container_of(work
, struct blk_mq_hw_ctx
, run_work
.work
);
1277 * If we are stopped, don't run the queue. The exception is if
1278 * BLK_MQ_S_START_ON_RUN is set. For that case, we auto-clear
1279 * the STOPPED bit and run it.
1281 if (test_bit(BLK_MQ_S_STOPPED
, &hctx
->state
)) {
1282 if (!test_bit(BLK_MQ_S_START_ON_RUN
, &hctx
->state
))
1285 clear_bit(BLK_MQ_S_START_ON_RUN
, &hctx
->state
);
1286 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1289 __blk_mq_run_hw_queue(hctx
);
1293 void blk_mq_delay_queue(struct blk_mq_hw_ctx
*hctx
, unsigned long msecs
)
1295 if (unlikely(!blk_mq_hw_queue_mapped(hctx
)))
1299 * Stop the hw queue, then modify currently delayed work.
1300 * This should prevent us from running the queue prematurely.
1301 * Mark the queue as auto-clearing STOPPED when it runs.
1303 blk_mq_stop_hw_queue(hctx
);
1304 set_bit(BLK_MQ_S_START_ON_RUN
, &hctx
->state
);
1305 kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx
),
1307 msecs_to_jiffies(msecs
));
1309 EXPORT_SYMBOL(blk_mq_delay_queue
);
1311 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx
*hctx
,
1315 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1317 trace_block_rq_insert(hctx
->queue
, rq
);
1320 list_add(&rq
->queuelist
, &ctx
->rq_list
);
1322 list_add_tail(&rq
->queuelist
, &ctx
->rq_list
);
1325 void __blk_mq_insert_request(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
,
1328 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1330 __blk_mq_insert_req_list(hctx
, rq
, at_head
);
1331 blk_mq_hctx_mark_pending(hctx
, ctx
);
1334 void blk_mq_insert_requests(struct blk_mq_hw_ctx
*hctx
, struct blk_mq_ctx
*ctx
,
1335 struct list_head
*list
)
1339 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1342 spin_lock(&ctx
->lock
);
1343 while (!list_empty(list
)) {
1346 rq
= list_first_entry(list
, struct request
, queuelist
);
1347 BUG_ON(rq
->mq_ctx
!= ctx
);
1348 list_del_init(&rq
->queuelist
);
1349 __blk_mq_insert_req_list(hctx
, rq
, false);
1351 blk_mq_hctx_mark_pending(hctx
, ctx
);
1352 spin_unlock(&ctx
->lock
);
1355 static int plug_ctx_cmp(void *priv
, struct list_head
*a
, struct list_head
*b
)
1357 struct request
*rqa
= container_of(a
, struct request
, queuelist
);
1358 struct request
*rqb
= container_of(b
, struct request
, queuelist
);
1360 return !(rqa
->mq_ctx
< rqb
->mq_ctx
||
1361 (rqa
->mq_ctx
== rqb
->mq_ctx
&&
1362 blk_rq_pos(rqa
) < blk_rq_pos(rqb
)));
1365 void blk_mq_flush_plug_list(struct blk_plug
*plug
, bool from_schedule
)
1367 struct blk_mq_ctx
*this_ctx
;
1368 struct request_queue
*this_q
;
1371 LIST_HEAD(ctx_list
);
1374 list_splice_init(&plug
->mq_list
, &list
);
1376 list_sort(NULL
, &list
, plug_ctx_cmp
);
1382 while (!list_empty(&list
)) {
1383 rq
= list_entry_rq(list
.next
);
1384 list_del_init(&rq
->queuelist
);
1386 if (rq
->mq_ctx
!= this_ctx
) {
1388 trace_block_unplug(this_q
, depth
, from_schedule
);
1389 blk_mq_sched_insert_requests(this_q
, this_ctx
,
1394 this_ctx
= rq
->mq_ctx
;
1400 list_add_tail(&rq
->queuelist
, &ctx_list
);
1404 * If 'this_ctx' is set, we know we have entries to complete
1405 * on 'ctx_list'. Do those.
1408 trace_block_unplug(this_q
, depth
, from_schedule
);
1409 blk_mq_sched_insert_requests(this_q
, this_ctx
, &ctx_list
,
1414 static void blk_mq_bio_to_request(struct request
*rq
, struct bio
*bio
)
1416 blk_init_request_from_bio(rq
, bio
);
1418 blk_account_io_start(rq
, true);
1421 static inline bool hctx_allow_merges(struct blk_mq_hw_ctx
*hctx
)
1423 return (hctx
->flags
& BLK_MQ_F_SHOULD_MERGE
) &&
1424 !blk_queue_nomerges(hctx
->queue
);
1427 static inline void blk_mq_queue_io(struct blk_mq_hw_ctx
*hctx
,
1428 struct blk_mq_ctx
*ctx
,
1431 spin_lock(&ctx
->lock
);
1432 __blk_mq_insert_request(hctx
, rq
, false);
1433 spin_unlock(&ctx
->lock
);
1436 static blk_qc_t
request_to_qc_t(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
)
1439 return blk_tag_to_qc_t(rq
->tag
, hctx
->queue_num
, false);
1441 return blk_tag_to_qc_t(rq
->internal_tag
, hctx
->queue_num
, true);
1444 static void __blk_mq_try_issue_directly(struct blk_mq_hw_ctx
*hctx
,
1446 blk_qc_t
*cookie
, bool may_sleep
)
1448 struct request_queue
*q
= rq
->q
;
1449 struct blk_mq_queue_data bd
= {
1453 blk_qc_t new_cookie
;
1455 bool run_queue
= true;
1457 /* RCU or SRCU read lock is needed before checking quiesced flag */
1458 if (blk_mq_hctx_stopped(hctx
) || blk_queue_quiesced(q
)) {
1466 if (!blk_mq_get_driver_tag(rq
, NULL
, false))
1469 new_cookie
= request_to_qc_t(hctx
, rq
);
1472 * For OK queue, we are done. For error, kill it. Any other
1473 * error (busy), just add it to our list as we previously
1476 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1479 *cookie
= new_cookie
;
1481 case BLK_STS_RESOURCE
:
1482 __blk_mq_requeue_request(rq
);
1485 *cookie
= BLK_QC_T_NONE
;
1486 blk_mq_end_request(rq
, ret
);
1491 blk_mq_sched_insert_request(rq
, false, run_queue
, false, may_sleep
);
1494 static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx
*hctx
,
1495 struct request
*rq
, blk_qc_t
*cookie
)
1497 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1499 __blk_mq_try_issue_directly(hctx
, rq
, cookie
, false);
1502 unsigned int srcu_idx
;
1506 srcu_idx
= srcu_read_lock(&hctx
->queue_rq_srcu
);
1507 __blk_mq_try_issue_directly(hctx
, rq
, cookie
, true);
1508 srcu_read_unlock(&hctx
->queue_rq_srcu
, srcu_idx
);
1512 static blk_qc_t
blk_mq_make_request(struct request_queue
*q
, struct bio
*bio
)
1514 const int is_sync
= op_is_sync(bio
->bi_opf
);
1515 const int is_flush_fua
= op_is_flush(bio
->bi_opf
);
1516 struct blk_mq_alloc_data data
= { .flags
= 0 };
1518 unsigned int request_count
= 0;
1519 struct blk_plug
*plug
;
1520 struct request
*same_queue_rq
= NULL
;
1522 unsigned int wb_acct
;
1524 blk_queue_bounce(q
, &bio
);
1526 blk_queue_split(q
, &bio
);
1528 if (bio_integrity_enabled(bio
) && bio_integrity_prep(bio
)) {
1530 return BLK_QC_T_NONE
;
1533 if (!is_flush_fua
&& !blk_queue_nomerges(q
) &&
1534 blk_attempt_plug_merge(q
, bio
, &request_count
, &same_queue_rq
))
1535 return BLK_QC_T_NONE
;
1537 if (blk_mq_sched_bio_merge(q
, bio
))
1538 return BLK_QC_T_NONE
;
1540 wb_acct
= wbt_wait(q
->rq_wb
, bio
, NULL
);
1542 trace_block_getrq(q
, bio
, bio
->bi_opf
);
1544 rq
= blk_mq_get_request(q
, bio
, bio
->bi_opf
, &data
);
1545 if (unlikely(!rq
)) {
1546 __wbt_done(q
->rq_wb
, wb_acct
);
1547 return BLK_QC_T_NONE
;
1550 wbt_track(&rq
->issue_stat
, wb_acct
);
1552 cookie
= request_to_qc_t(data
.hctx
, rq
);
1554 plug
= current
->plug
;
1555 if (unlikely(is_flush_fua
)) {
1556 blk_mq_put_ctx(data
.ctx
);
1557 blk_mq_bio_to_request(rq
, bio
);
1559 blk_mq_sched_insert_request(rq
, false, true, true,
1562 blk_insert_flush(rq
);
1563 blk_mq_run_hw_queue(data
.hctx
, true);
1565 } else if (plug
&& q
->nr_hw_queues
== 1) {
1566 struct request
*last
= NULL
;
1568 blk_mq_put_ctx(data
.ctx
);
1569 blk_mq_bio_to_request(rq
, bio
);
1572 * @request_count may become stale because of schedule
1573 * out, so check the list again.
1575 if (list_empty(&plug
->mq_list
))
1577 else if (blk_queue_nomerges(q
))
1578 request_count
= blk_plug_queued_count(q
);
1581 trace_block_plug(q
);
1583 last
= list_entry_rq(plug
->mq_list
.prev
);
1585 if (request_count
>= BLK_MAX_REQUEST_COUNT
|| (last
&&
1586 blk_rq_bytes(last
) >= BLK_PLUG_FLUSH_SIZE
)) {
1587 blk_flush_plug_list(plug
, false);
1588 trace_block_plug(q
);
1591 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1592 } else if (plug
&& !blk_queue_nomerges(q
)) {
1593 blk_mq_bio_to_request(rq
, bio
);
1596 * We do limited plugging. If the bio can be merged, do that.
1597 * Otherwise the existing request in the plug list will be
1598 * issued. So the plug list will have one request at most
1599 * The plug list might get flushed before this. If that happens,
1600 * the plug list is empty, and same_queue_rq is invalid.
1602 if (list_empty(&plug
->mq_list
))
1603 same_queue_rq
= NULL
;
1605 list_del_init(&same_queue_rq
->queuelist
);
1606 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1608 blk_mq_put_ctx(data
.ctx
);
1610 if (same_queue_rq
) {
1611 data
.hctx
= blk_mq_map_queue(q
,
1612 same_queue_rq
->mq_ctx
->cpu
);
1613 blk_mq_try_issue_directly(data
.hctx
, same_queue_rq
,
1616 } else if (q
->nr_hw_queues
> 1 && is_sync
) {
1617 blk_mq_put_ctx(data
.ctx
);
1618 blk_mq_bio_to_request(rq
, bio
);
1619 blk_mq_try_issue_directly(data
.hctx
, rq
, &cookie
);
1620 } else if (q
->elevator
) {
1621 blk_mq_put_ctx(data
.ctx
);
1622 blk_mq_bio_to_request(rq
, bio
);
1623 blk_mq_sched_insert_request(rq
, false, true, true, true);
1625 blk_mq_put_ctx(data
.ctx
);
1626 blk_mq_bio_to_request(rq
, bio
);
1627 blk_mq_queue_io(data
.hctx
, data
.ctx
, rq
);
1628 blk_mq_run_hw_queue(data
.hctx
, true);
1634 void blk_mq_free_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
1635 unsigned int hctx_idx
)
1639 if (tags
->rqs
&& set
->ops
->exit_request
) {
1642 for (i
= 0; i
< tags
->nr_tags
; i
++) {
1643 struct request
*rq
= tags
->static_rqs
[i
];
1647 set
->ops
->exit_request(set
, rq
, hctx_idx
);
1648 tags
->static_rqs
[i
] = NULL
;
1652 while (!list_empty(&tags
->page_list
)) {
1653 page
= list_first_entry(&tags
->page_list
, struct page
, lru
);
1654 list_del_init(&page
->lru
);
1656 * Remove kmemleak object previously allocated in
1657 * blk_mq_init_rq_map().
1659 kmemleak_free(page_address(page
));
1660 __free_pages(page
, page
->private);
1664 void blk_mq_free_rq_map(struct blk_mq_tags
*tags
)
1668 kfree(tags
->static_rqs
);
1669 tags
->static_rqs
= NULL
;
1671 blk_mq_free_tags(tags
);
1674 struct blk_mq_tags
*blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
,
1675 unsigned int hctx_idx
,
1676 unsigned int nr_tags
,
1677 unsigned int reserved_tags
)
1679 struct blk_mq_tags
*tags
;
1682 node
= blk_mq_hw_queue_to_node(set
->mq_map
, hctx_idx
);
1683 if (node
== NUMA_NO_NODE
)
1684 node
= set
->numa_node
;
1686 tags
= blk_mq_init_tags(nr_tags
, reserved_tags
, node
,
1687 BLK_MQ_FLAG_TO_ALLOC_POLICY(set
->flags
));
1691 tags
->rqs
= kzalloc_node(nr_tags
* sizeof(struct request
*),
1692 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
1695 blk_mq_free_tags(tags
);
1699 tags
->static_rqs
= kzalloc_node(nr_tags
* sizeof(struct request
*),
1700 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
1702 if (!tags
->static_rqs
) {
1704 blk_mq_free_tags(tags
);
1711 static size_t order_to_size(unsigned int order
)
1713 return (size_t)PAGE_SIZE
<< order
;
1716 int blk_mq_alloc_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
1717 unsigned int hctx_idx
, unsigned int depth
)
1719 unsigned int i
, j
, entries_per_page
, max_order
= 4;
1720 size_t rq_size
, left
;
1723 node
= blk_mq_hw_queue_to_node(set
->mq_map
, hctx_idx
);
1724 if (node
== NUMA_NO_NODE
)
1725 node
= set
->numa_node
;
1727 INIT_LIST_HEAD(&tags
->page_list
);
1730 * rq_size is the size of the request plus driver payload, rounded
1731 * to the cacheline size
1733 rq_size
= round_up(sizeof(struct request
) + set
->cmd_size
,
1735 left
= rq_size
* depth
;
1737 for (i
= 0; i
< depth
; ) {
1738 int this_order
= max_order
;
1743 while (this_order
&& left
< order_to_size(this_order
- 1))
1747 page
= alloc_pages_node(node
,
1748 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
| __GFP_ZERO
,
1754 if (order_to_size(this_order
) < rq_size
)
1761 page
->private = this_order
;
1762 list_add_tail(&page
->lru
, &tags
->page_list
);
1764 p
= page_address(page
);
1766 * Allow kmemleak to scan these pages as they contain pointers
1767 * to additional allocations like via ops->init_request().
1769 kmemleak_alloc(p
, order_to_size(this_order
), 1, GFP_NOIO
);
1770 entries_per_page
= order_to_size(this_order
) / rq_size
;
1771 to_do
= min(entries_per_page
, depth
- i
);
1772 left
-= to_do
* rq_size
;
1773 for (j
= 0; j
< to_do
; j
++) {
1774 struct request
*rq
= p
;
1776 tags
->static_rqs
[i
] = rq
;
1777 if (set
->ops
->init_request
) {
1778 if (set
->ops
->init_request(set
, rq
, hctx_idx
,
1780 tags
->static_rqs
[i
] = NULL
;
1792 blk_mq_free_rqs(set
, tags
, hctx_idx
);
1797 * 'cpu' is going away. splice any existing rq_list entries from this
1798 * software queue to the hw queue dispatch list, and ensure that it
1801 static int blk_mq_hctx_notify_dead(unsigned int cpu
, struct hlist_node
*node
)
1803 struct blk_mq_hw_ctx
*hctx
;
1804 struct blk_mq_ctx
*ctx
;
1807 hctx
= hlist_entry_safe(node
, struct blk_mq_hw_ctx
, cpuhp_dead
);
1808 ctx
= __blk_mq_get_ctx(hctx
->queue
, cpu
);
1810 spin_lock(&ctx
->lock
);
1811 if (!list_empty(&ctx
->rq_list
)) {
1812 list_splice_init(&ctx
->rq_list
, &tmp
);
1813 blk_mq_hctx_clear_pending(hctx
, ctx
);
1815 spin_unlock(&ctx
->lock
);
1817 if (list_empty(&tmp
))
1820 spin_lock(&hctx
->lock
);
1821 list_splice_tail_init(&tmp
, &hctx
->dispatch
);
1822 spin_unlock(&hctx
->lock
);
1824 blk_mq_run_hw_queue(hctx
, true);
1828 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx
*hctx
)
1830 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD
,
1834 /* hctx->ctxs will be freed in queue's release handler */
1835 static void blk_mq_exit_hctx(struct request_queue
*q
,
1836 struct blk_mq_tag_set
*set
,
1837 struct blk_mq_hw_ctx
*hctx
, unsigned int hctx_idx
)
1839 blk_mq_debugfs_unregister_hctx(hctx
);
1841 blk_mq_tag_idle(hctx
);
1843 if (set
->ops
->exit_request
)
1844 set
->ops
->exit_request(set
, hctx
->fq
->flush_rq
, hctx_idx
);
1846 blk_mq_sched_exit_hctx(q
, hctx
, hctx_idx
);
1848 if (set
->ops
->exit_hctx
)
1849 set
->ops
->exit_hctx(hctx
, hctx_idx
);
1851 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
1852 cleanup_srcu_struct(&hctx
->queue_rq_srcu
);
1854 blk_mq_remove_cpuhp(hctx
);
1855 blk_free_flush_queue(hctx
->fq
);
1856 sbitmap_free(&hctx
->ctx_map
);
1859 static void blk_mq_exit_hw_queues(struct request_queue
*q
,
1860 struct blk_mq_tag_set
*set
, int nr_queue
)
1862 struct blk_mq_hw_ctx
*hctx
;
1865 queue_for_each_hw_ctx(q
, hctx
, i
) {
1868 blk_mq_exit_hctx(q
, set
, hctx
, i
);
1872 static int blk_mq_init_hctx(struct request_queue
*q
,
1873 struct blk_mq_tag_set
*set
,
1874 struct blk_mq_hw_ctx
*hctx
, unsigned hctx_idx
)
1878 node
= hctx
->numa_node
;
1879 if (node
== NUMA_NO_NODE
)
1880 node
= hctx
->numa_node
= set
->numa_node
;
1882 INIT_DELAYED_WORK(&hctx
->run_work
, blk_mq_run_work_fn
);
1883 spin_lock_init(&hctx
->lock
);
1884 INIT_LIST_HEAD(&hctx
->dispatch
);
1886 hctx
->queue_num
= hctx_idx
;
1887 hctx
->flags
= set
->flags
& ~BLK_MQ_F_TAG_SHARED
;
1889 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD
, &hctx
->cpuhp_dead
);
1891 hctx
->tags
= set
->tags
[hctx_idx
];
1894 * Allocate space for all possible cpus to avoid allocation at
1897 hctx
->ctxs
= kmalloc_node(nr_cpu_ids
* sizeof(void *),
1900 goto unregister_cpu_notifier
;
1902 if (sbitmap_init_node(&hctx
->ctx_map
, nr_cpu_ids
, ilog2(8), GFP_KERNEL
,
1908 if (set
->ops
->init_hctx
&&
1909 set
->ops
->init_hctx(hctx
, set
->driver_data
, hctx_idx
))
1912 if (blk_mq_sched_init_hctx(q
, hctx
, hctx_idx
))
1915 hctx
->fq
= blk_alloc_flush_queue(q
, hctx
->numa_node
, set
->cmd_size
);
1917 goto sched_exit_hctx
;
1919 if (set
->ops
->init_request
&&
1920 set
->ops
->init_request(set
, hctx
->fq
->flush_rq
, hctx_idx
,
1924 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
1925 init_srcu_struct(&hctx
->queue_rq_srcu
);
1927 blk_mq_debugfs_register_hctx(q
, hctx
);
1934 blk_mq_sched_exit_hctx(q
, hctx
, hctx_idx
);
1936 if (set
->ops
->exit_hctx
)
1937 set
->ops
->exit_hctx(hctx
, hctx_idx
);
1939 sbitmap_free(&hctx
->ctx_map
);
1942 unregister_cpu_notifier
:
1943 blk_mq_remove_cpuhp(hctx
);
1947 static void blk_mq_init_cpu_queues(struct request_queue
*q
,
1948 unsigned int nr_hw_queues
)
1952 for_each_possible_cpu(i
) {
1953 struct blk_mq_ctx
*__ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
1954 struct blk_mq_hw_ctx
*hctx
;
1957 spin_lock_init(&__ctx
->lock
);
1958 INIT_LIST_HEAD(&__ctx
->rq_list
);
1961 /* If the cpu isn't online, the cpu is mapped to first hctx */
1965 hctx
= blk_mq_map_queue(q
, i
);
1968 * Set local node, IFF we have more than one hw queue. If
1969 * not, we remain on the home node of the device
1971 if (nr_hw_queues
> 1 && hctx
->numa_node
== NUMA_NO_NODE
)
1972 hctx
->numa_node
= local_memory_node(cpu_to_node(i
));
1976 static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
, int hctx_idx
)
1980 set
->tags
[hctx_idx
] = blk_mq_alloc_rq_map(set
, hctx_idx
,
1981 set
->queue_depth
, set
->reserved_tags
);
1982 if (!set
->tags
[hctx_idx
])
1985 ret
= blk_mq_alloc_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
,
1990 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
1991 set
->tags
[hctx_idx
] = NULL
;
1995 static void blk_mq_free_map_and_requests(struct blk_mq_tag_set
*set
,
1996 unsigned int hctx_idx
)
1998 if (set
->tags
[hctx_idx
]) {
1999 blk_mq_free_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
);
2000 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
2001 set
->tags
[hctx_idx
] = NULL
;
2005 static void blk_mq_map_swqueue(struct request_queue
*q
,
2006 const struct cpumask
*online_mask
)
2008 unsigned int i
, hctx_idx
;
2009 struct blk_mq_hw_ctx
*hctx
;
2010 struct blk_mq_ctx
*ctx
;
2011 struct blk_mq_tag_set
*set
= q
->tag_set
;
2014 * Avoid others reading imcomplete hctx->cpumask through sysfs
2016 mutex_lock(&q
->sysfs_lock
);
2018 queue_for_each_hw_ctx(q
, hctx
, i
) {
2019 cpumask_clear(hctx
->cpumask
);
2024 * Map software to hardware queues
2026 for_each_possible_cpu(i
) {
2027 /* If the cpu isn't online, the cpu is mapped to first hctx */
2028 if (!cpumask_test_cpu(i
, online_mask
))
2031 hctx_idx
= q
->mq_map
[i
];
2032 /* unmapped hw queue can be remapped after CPU topo changed */
2033 if (!set
->tags
[hctx_idx
] &&
2034 !__blk_mq_alloc_rq_map(set
, hctx_idx
)) {
2036 * If tags initialization fail for some hctx,
2037 * that hctx won't be brought online. In this
2038 * case, remap the current ctx to hctx[0] which
2039 * is guaranteed to always have tags allocated
2044 ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
2045 hctx
= blk_mq_map_queue(q
, i
);
2047 cpumask_set_cpu(i
, hctx
->cpumask
);
2048 ctx
->index_hw
= hctx
->nr_ctx
;
2049 hctx
->ctxs
[hctx
->nr_ctx
++] = ctx
;
2052 mutex_unlock(&q
->sysfs_lock
);
2054 queue_for_each_hw_ctx(q
, hctx
, i
) {
2056 * If no software queues are mapped to this hardware queue,
2057 * disable it and free the request entries.
2059 if (!hctx
->nr_ctx
) {
2060 /* Never unmap queue 0. We need it as a
2061 * fallback in case of a new remap fails
2064 if (i
&& set
->tags
[i
])
2065 blk_mq_free_map_and_requests(set
, i
);
2071 hctx
->tags
= set
->tags
[i
];
2072 WARN_ON(!hctx
->tags
);
2075 * Set the map size to the number of mapped software queues.
2076 * This is more accurate and more efficient than looping
2077 * over all possibly mapped software queues.
2079 sbitmap_resize(&hctx
->ctx_map
, hctx
->nr_ctx
);
2082 * Initialize batch roundrobin counts
2084 hctx
->next_cpu
= cpumask_first(hctx
->cpumask
);
2085 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
2089 static void queue_set_hctx_shared(struct request_queue
*q
, bool shared
)
2091 struct blk_mq_hw_ctx
*hctx
;
2094 queue_for_each_hw_ctx(q
, hctx
, i
) {
2096 hctx
->flags
|= BLK_MQ_F_TAG_SHARED
;
2098 hctx
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2102 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set
*set
, bool shared
)
2104 struct request_queue
*q
;
2106 lockdep_assert_held(&set
->tag_list_lock
);
2108 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
2109 blk_mq_freeze_queue(q
);
2110 queue_set_hctx_shared(q
, shared
);
2111 blk_mq_unfreeze_queue(q
);
2115 static void blk_mq_del_queue_tag_set(struct request_queue
*q
)
2117 struct blk_mq_tag_set
*set
= q
->tag_set
;
2119 mutex_lock(&set
->tag_list_lock
);
2120 list_del_rcu(&q
->tag_set_list
);
2121 INIT_LIST_HEAD(&q
->tag_set_list
);
2122 if (list_is_singular(&set
->tag_list
)) {
2123 /* just transitioned to unshared */
2124 set
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2125 /* update existing queue */
2126 blk_mq_update_tag_set_depth(set
, false);
2128 mutex_unlock(&set
->tag_list_lock
);
2133 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set
*set
,
2134 struct request_queue
*q
)
2138 mutex_lock(&set
->tag_list_lock
);
2140 /* Check to see if we're transitioning to shared (from 1 to 2 queues). */
2141 if (!list_empty(&set
->tag_list
) && !(set
->flags
& BLK_MQ_F_TAG_SHARED
)) {
2142 set
->flags
|= BLK_MQ_F_TAG_SHARED
;
2143 /* update existing queue */
2144 blk_mq_update_tag_set_depth(set
, true);
2146 if (set
->flags
& BLK_MQ_F_TAG_SHARED
)
2147 queue_set_hctx_shared(q
, true);
2148 list_add_tail_rcu(&q
->tag_set_list
, &set
->tag_list
);
2150 mutex_unlock(&set
->tag_list_lock
);
2154 * It is the actual release handler for mq, but we do it from
2155 * request queue's release handler for avoiding use-after-free
2156 * and headache because q->mq_kobj shouldn't have been introduced,
2157 * but we can't group ctx/kctx kobj without it.
2159 void blk_mq_release(struct request_queue
*q
)
2161 struct blk_mq_hw_ctx
*hctx
;
2164 /* hctx kobj stays in hctx */
2165 queue_for_each_hw_ctx(q
, hctx
, i
) {
2168 kobject_put(&hctx
->kobj
);
2173 kfree(q
->queue_hw_ctx
);
2176 * release .mq_kobj and sw queue's kobject now because
2177 * both share lifetime with request queue.
2179 blk_mq_sysfs_deinit(q
);
2181 free_percpu(q
->queue_ctx
);
2184 struct request_queue
*blk_mq_init_queue(struct blk_mq_tag_set
*set
)
2186 struct request_queue
*uninit_q
, *q
;
2188 uninit_q
= blk_alloc_queue_node(GFP_KERNEL
, set
->numa_node
);
2190 return ERR_PTR(-ENOMEM
);
2192 q
= blk_mq_init_allocated_queue(set
, uninit_q
);
2194 blk_cleanup_queue(uninit_q
);
2198 EXPORT_SYMBOL(blk_mq_init_queue
);
2200 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set
*set
,
2201 struct request_queue
*q
)
2204 struct blk_mq_hw_ctx
**hctxs
= q
->queue_hw_ctx
;
2206 blk_mq_sysfs_unregister(q
);
2207 for (i
= 0; i
< set
->nr_hw_queues
; i
++) {
2213 node
= blk_mq_hw_queue_to_node(q
->mq_map
, i
);
2214 hctxs
[i
] = kzalloc_node(sizeof(struct blk_mq_hw_ctx
),
2219 if (!zalloc_cpumask_var_node(&hctxs
[i
]->cpumask
, GFP_KERNEL
,
2226 atomic_set(&hctxs
[i
]->nr_active
, 0);
2227 hctxs
[i
]->numa_node
= node
;
2228 hctxs
[i
]->queue_num
= i
;
2230 if (blk_mq_init_hctx(q
, set
, hctxs
[i
], i
)) {
2231 free_cpumask_var(hctxs
[i
]->cpumask
);
2236 blk_mq_hctx_kobj_init(hctxs
[i
]);
2238 for (j
= i
; j
< q
->nr_hw_queues
; j
++) {
2239 struct blk_mq_hw_ctx
*hctx
= hctxs
[j
];
2243 blk_mq_free_map_and_requests(set
, j
);
2244 blk_mq_exit_hctx(q
, set
, hctx
, j
);
2245 kobject_put(&hctx
->kobj
);
2250 q
->nr_hw_queues
= i
;
2251 blk_mq_sysfs_register(q
);
2254 struct request_queue
*blk_mq_init_allocated_queue(struct blk_mq_tag_set
*set
,
2255 struct request_queue
*q
)
2257 /* mark the queue as mq asap */
2258 q
->mq_ops
= set
->ops
;
2260 q
->poll_cb
= blk_stat_alloc_callback(blk_mq_poll_stats_fn
,
2261 blk_mq_poll_stats_bkt
,
2262 BLK_MQ_POLL_STATS_BKTS
, q
);
2266 q
->queue_ctx
= alloc_percpu(struct blk_mq_ctx
);
2270 /* init q->mq_kobj and sw queues' kobjects */
2271 blk_mq_sysfs_init(q
);
2273 q
->queue_hw_ctx
= kzalloc_node(nr_cpu_ids
* sizeof(*(q
->queue_hw_ctx
)),
2274 GFP_KERNEL
, set
->numa_node
);
2275 if (!q
->queue_hw_ctx
)
2278 q
->mq_map
= set
->mq_map
;
2280 blk_mq_realloc_hw_ctxs(set
, q
);
2281 if (!q
->nr_hw_queues
)
2284 INIT_WORK(&q
->timeout_work
, blk_mq_timeout_work
);
2285 blk_queue_rq_timeout(q
, set
->timeout
? set
->timeout
: 30 * HZ
);
2287 q
->nr_queues
= nr_cpu_ids
;
2289 q
->queue_flags
|= QUEUE_FLAG_MQ_DEFAULT
;
2291 if (!(set
->flags
& BLK_MQ_F_SG_MERGE
))
2292 q
->queue_flags
|= 1 << QUEUE_FLAG_NO_SG_MERGE
;
2294 q
->sg_reserved_size
= INT_MAX
;
2296 INIT_DELAYED_WORK(&q
->requeue_work
, blk_mq_requeue_work
);
2297 INIT_LIST_HEAD(&q
->requeue_list
);
2298 spin_lock_init(&q
->requeue_lock
);
2300 blk_queue_make_request(q
, blk_mq_make_request
);
2303 * Do this after blk_queue_make_request() overrides it...
2305 q
->nr_requests
= set
->queue_depth
;
2308 * Default to classic polling
2312 if (set
->ops
->complete
)
2313 blk_queue_softirq_done(q
, set
->ops
->complete
);
2315 blk_mq_init_cpu_queues(q
, set
->nr_hw_queues
);
2318 mutex_lock(&all_q_mutex
);
2320 list_add_tail(&q
->all_q_node
, &all_q_list
);
2321 blk_mq_add_queue_tag_set(set
, q
);
2322 blk_mq_map_swqueue(q
, cpu_online_mask
);
2324 mutex_unlock(&all_q_mutex
);
2327 if (!(set
->flags
& BLK_MQ_F_NO_SCHED
)) {
2330 ret
= blk_mq_sched_init(q
);
2332 return ERR_PTR(ret
);
2338 kfree(q
->queue_hw_ctx
);
2340 free_percpu(q
->queue_ctx
);
2343 return ERR_PTR(-ENOMEM
);
2345 EXPORT_SYMBOL(blk_mq_init_allocated_queue
);
2347 void blk_mq_free_queue(struct request_queue
*q
)
2349 struct blk_mq_tag_set
*set
= q
->tag_set
;
2351 mutex_lock(&all_q_mutex
);
2352 list_del_init(&q
->all_q_node
);
2353 mutex_unlock(&all_q_mutex
);
2355 blk_mq_del_queue_tag_set(q
);
2357 blk_mq_exit_hw_queues(q
, set
, set
->nr_hw_queues
);
2360 /* Basically redo blk_mq_init_queue with queue frozen */
2361 static void blk_mq_queue_reinit(struct request_queue
*q
,
2362 const struct cpumask
*online_mask
)
2364 WARN_ON_ONCE(!atomic_read(&q
->mq_freeze_depth
));
2366 blk_mq_debugfs_unregister_hctxs(q
);
2367 blk_mq_sysfs_unregister(q
);
2370 * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
2371 * we should change hctx numa_node according to new topology (this
2372 * involves free and re-allocate memory, worthy doing?)
2375 blk_mq_map_swqueue(q
, online_mask
);
2377 blk_mq_sysfs_register(q
);
2378 blk_mq_debugfs_register_hctxs(q
);
2382 * New online cpumask which is going to be set in this hotplug event.
2383 * Declare this cpumasks as global as cpu-hotplug operation is invoked
2384 * one-by-one and dynamically allocating this could result in a failure.
2386 static struct cpumask cpuhp_online_new
;
2388 static void blk_mq_queue_reinit_work(void)
2390 struct request_queue
*q
;
2392 mutex_lock(&all_q_mutex
);
2394 * We need to freeze and reinit all existing queues. Freezing
2395 * involves synchronous wait for an RCU grace period and doing it
2396 * one by one may take a long time. Start freezing all queues in
2397 * one swoop and then wait for the completions so that freezing can
2398 * take place in parallel.
2400 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2401 blk_freeze_queue_start(q
);
2402 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2403 blk_mq_freeze_queue_wait(q
);
2405 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2406 blk_mq_queue_reinit(q
, &cpuhp_online_new
);
2408 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2409 blk_mq_unfreeze_queue(q
);
2411 mutex_unlock(&all_q_mutex
);
2414 static int blk_mq_queue_reinit_dead(unsigned int cpu
)
2416 cpumask_copy(&cpuhp_online_new
, cpu_online_mask
);
2417 blk_mq_queue_reinit_work();
2422 * Before hotadded cpu starts handling requests, new mappings must be
2423 * established. Otherwise, these requests in hw queue might never be
2426 * For example, there is a single hw queue (hctx) and two CPU queues (ctx0
2427 * for CPU0, and ctx1 for CPU1).
2429 * Now CPU1 is just onlined and a request is inserted into ctx1->rq_list
2430 * and set bit0 in pending bitmap as ctx1->index_hw is still zero.
2432 * And then while running hw queue, blk_mq_flush_busy_ctxs() finds bit0 is set
2433 * in pending bitmap and tries to retrieve requests in hctx->ctxs[0]->rq_list.
2434 * But htx->ctxs[0] is a pointer to ctx0, so the request in ctx1->rq_list is
2437 static int blk_mq_queue_reinit_prepare(unsigned int cpu
)
2439 cpumask_copy(&cpuhp_online_new
, cpu_online_mask
);
2440 cpumask_set_cpu(cpu
, &cpuhp_online_new
);
2441 blk_mq_queue_reinit_work();
2445 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2449 for (i
= 0; i
< set
->nr_hw_queues
; i
++)
2450 if (!__blk_mq_alloc_rq_map(set
, i
))
2457 blk_mq_free_rq_map(set
->tags
[i
]);
2463 * Allocate the request maps associated with this tag_set. Note that this
2464 * may reduce the depth asked for, if memory is tight. set->queue_depth
2465 * will be updated to reflect the allocated depth.
2467 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2472 depth
= set
->queue_depth
;
2474 err
= __blk_mq_alloc_rq_maps(set
);
2478 set
->queue_depth
>>= 1;
2479 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
) {
2483 } while (set
->queue_depth
);
2485 if (!set
->queue_depth
|| err
) {
2486 pr_err("blk-mq: failed to allocate request map\n");
2490 if (depth
!= set
->queue_depth
)
2491 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2492 depth
, set
->queue_depth
);
2497 static int blk_mq_update_queue_map(struct blk_mq_tag_set
*set
)
2499 if (set
->ops
->map_queues
)
2500 return set
->ops
->map_queues(set
);
2502 return blk_mq_map_queues(set
);
2506 * Alloc a tag set to be associated with one or more request queues.
2507 * May fail with EINVAL for various error conditions. May adjust the
2508 * requested depth down, if if it too large. In that case, the set
2509 * value will be stored in set->queue_depth.
2511 int blk_mq_alloc_tag_set(struct blk_mq_tag_set
*set
)
2515 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH
> 1 << BLK_MQ_UNIQUE_TAG_BITS
);
2517 if (!set
->nr_hw_queues
)
2519 if (!set
->queue_depth
)
2521 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
)
2524 if (!set
->ops
->queue_rq
)
2527 if (set
->queue_depth
> BLK_MQ_MAX_DEPTH
) {
2528 pr_info("blk-mq: reduced tag depth to %u\n",
2530 set
->queue_depth
= BLK_MQ_MAX_DEPTH
;
2534 * If a crashdump is active, then we are potentially in a very
2535 * memory constrained environment. Limit us to 1 queue and
2536 * 64 tags to prevent using too much memory.
2538 if (is_kdump_kernel()) {
2539 set
->nr_hw_queues
= 1;
2540 set
->queue_depth
= min(64U, set
->queue_depth
);
2543 * There is no use for more h/w queues than cpus.
2545 if (set
->nr_hw_queues
> nr_cpu_ids
)
2546 set
->nr_hw_queues
= nr_cpu_ids
;
2548 set
->tags
= kzalloc_node(nr_cpu_ids
* sizeof(struct blk_mq_tags
*),
2549 GFP_KERNEL
, set
->numa_node
);
2554 set
->mq_map
= kzalloc_node(sizeof(*set
->mq_map
) * nr_cpu_ids
,
2555 GFP_KERNEL
, set
->numa_node
);
2559 ret
= blk_mq_update_queue_map(set
);
2561 goto out_free_mq_map
;
2563 ret
= blk_mq_alloc_rq_maps(set
);
2565 goto out_free_mq_map
;
2567 mutex_init(&set
->tag_list_lock
);
2568 INIT_LIST_HEAD(&set
->tag_list
);
2580 EXPORT_SYMBOL(blk_mq_alloc_tag_set
);
2582 void blk_mq_free_tag_set(struct blk_mq_tag_set
*set
)
2586 for (i
= 0; i
< nr_cpu_ids
; i
++)
2587 blk_mq_free_map_and_requests(set
, i
);
2595 EXPORT_SYMBOL(blk_mq_free_tag_set
);
2597 int blk_mq_update_nr_requests(struct request_queue
*q
, unsigned int nr
)
2599 struct blk_mq_tag_set
*set
= q
->tag_set
;
2600 struct blk_mq_hw_ctx
*hctx
;
2606 blk_mq_freeze_queue(q
);
2609 queue_for_each_hw_ctx(q
, hctx
, i
) {
2613 * If we're using an MQ scheduler, just update the scheduler
2614 * queue depth. This is similar to what the old code would do.
2616 if (!hctx
->sched_tags
) {
2617 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->tags
,
2618 min(nr
, set
->queue_depth
),
2621 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->sched_tags
,
2629 q
->nr_requests
= nr
;
2631 blk_mq_unfreeze_queue(q
);
2636 static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
,
2639 struct request_queue
*q
;
2641 lockdep_assert_held(&set
->tag_list_lock
);
2643 if (nr_hw_queues
> nr_cpu_ids
)
2644 nr_hw_queues
= nr_cpu_ids
;
2645 if (nr_hw_queues
< 1 || nr_hw_queues
== set
->nr_hw_queues
)
2648 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
2649 blk_mq_freeze_queue(q
);
2651 set
->nr_hw_queues
= nr_hw_queues
;
2652 blk_mq_update_queue_map(set
);
2653 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
2654 blk_mq_realloc_hw_ctxs(set
, q
);
2655 blk_mq_queue_reinit(q
, cpu_online_mask
);
2658 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
2659 blk_mq_unfreeze_queue(q
);
2662 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
, int nr_hw_queues
)
2664 mutex_lock(&set
->tag_list_lock
);
2665 __blk_mq_update_nr_hw_queues(set
, nr_hw_queues
);
2666 mutex_unlock(&set
->tag_list_lock
);
2668 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues
);
2670 /* Enable polling stats and return whether they were already enabled. */
2671 static bool blk_poll_stats_enable(struct request_queue
*q
)
2673 if (test_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
) ||
2674 test_and_set_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
))
2676 blk_stat_add_callback(q
, q
->poll_cb
);
2680 static void blk_mq_poll_stats_start(struct request_queue
*q
)
2683 * We don't arm the callback if polling stats are not enabled or the
2684 * callback is already active.
2686 if (!test_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
) ||
2687 blk_stat_is_active(q
->poll_cb
))
2690 blk_stat_activate_msecs(q
->poll_cb
, 100);
2693 static void blk_mq_poll_stats_fn(struct blk_stat_callback
*cb
)
2695 struct request_queue
*q
= cb
->data
;
2698 for (bucket
= 0; bucket
< BLK_MQ_POLL_STATS_BKTS
; bucket
++) {
2699 if (cb
->stat
[bucket
].nr_samples
)
2700 q
->poll_stat
[bucket
] = cb
->stat
[bucket
];
2704 static unsigned long blk_mq_poll_nsecs(struct request_queue
*q
,
2705 struct blk_mq_hw_ctx
*hctx
,
2708 unsigned long ret
= 0;
2712 * If stats collection isn't on, don't sleep but turn it on for
2715 if (!blk_poll_stats_enable(q
))
2719 * As an optimistic guess, use half of the mean service time
2720 * for this type of request. We can (and should) make this smarter.
2721 * For instance, if the completion latencies are tight, we can
2722 * get closer than just half the mean. This is especially
2723 * important on devices where the completion latencies are longer
2724 * than ~10 usec. We do use the stats for the relevant IO size
2725 * if available which does lead to better estimates.
2727 bucket
= blk_mq_poll_stats_bkt(rq
);
2731 if (q
->poll_stat
[bucket
].nr_samples
)
2732 ret
= (q
->poll_stat
[bucket
].mean
+ 1) / 2;
2737 static bool blk_mq_poll_hybrid_sleep(struct request_queue
*q
,
2738 struct blk_mq_hw_ctx
*hctx
,
2741 struct hrtimer_sleeper hs
;
2742 enum hrtimer_mode mode
;
2746 if (test_bit(REQ_ATOM_POLL_SLEPT
, &rq
->atomic_flags
))
2752 * -1: don't ever hybrid sleep
2753 * 0: use half of prev avg
2754 * >0: use this specific value
2756 if (q
->poll_nsec
== -1)
2758 else if (q
->poll_nsec
> 0)
2759 nsecs
= q
->poll_nsec
;
2761 nsecs
= blk_mq_poll_nsecs(q
, hctx
, rq
);
2766 set_bit(REQ_ATOM_POLL_SLEPT
, &rq
->atomic_flags
);
2769 * This will be replaced with the stats tracking code, using
2770 * 'avg_completion_time / 2' as the pre-sleep target.
2774 mode
= HRTIMER_MODE_REL
;
2775 hrtimer_init_on_stack(&hs
.timer
, CLOCK_MONOTONIC
, mode
);
2776 hrtimer_set_expires(&hs
.timer
, kt
);
2778 hrtimer_init_sleeper(&hs
, current
);
2780 if (test_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
))
2782 set_current_state(TASK_UNINTERRUPTIBLE
);
2783 hrtimer_start_expires(&hs
.timer
, mode
);
2786 hrtimer_cancel(&hs
.timer
);
2787 mode
= HRTIMER_MODE_ABS
;
2788 } while (hs
.task
&& !signal_pending(current
));
2790 __set_current_state(TASK_RUNNING
);
2791 destroy_hrtimer_on_stack(&hs
.timer
);
2795 static bool __blk_mq_poll(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
)
2797 struct request_queue
*q
= hctx
->queue
;
2801 * If we sleep, have the caller restart the poll loop to reset
2802 * the state. Like for the other success return cases, the
2803 * caller is responsible for checking if the IO completed. If
2804 * the IO isn't complete, we'll get called again and will go
2805 * straight to the busy poll loop.
2807 if (blk_mq_poll_hybrid_sleep(q
, hctx
, rq
))
2810 hctx
->poll_considered
++;
2812 state
= current
->state
;
2813 while (!need_resched()) {
2816 hctx
->poll_invoked
++;
2818 ret
= q
->mq_ops
->poll(hctx
, rq
->tag
);
2820 hctx
->poll_success
++;
2821 set_current_state(TASK_RUNNING
);
2825 if (signal_pending_state(state
, current
))
2826 set_current_state(TASK_RUNNING
);
2828 if (current
->state
== TASK_RUNNING
)
2838 bool blk_mq_poll(struct request_queue
*q
, blk_qc_t cookie
)
2840 struct blk_mq_hw_ctx
*hctx
;
2841 struct blk_plug
*plug
;
2844 if (!q
->mq_ops
|| !q
->mq_ops
->poll
|| !blk_qc_t_valid(cookie
) ||
2845 !test_bit(QUEUE_FLAG_POLL
, &q
->queue_flags
))
2848 plug
= current
->plug
;
2850 blk_flush_plug_list(plug
, false);
2852 hctx
= q
->queue_hw_ctx
[blk_qc_t_to_queue_num(cookie
)];
2853 if (!blk_qc_t_is_internal(cookie
))
2854 rq
= blk_mq_tag_to_rq(hctx
->tags
, blk_qc_t_to_tag(cookie
));
2856 rq
= blk_mq_tag_to_rq(hctx
->sched_tags
, blk_qc_t_to_tag(cookie
));
2858 * With scheduling, if the request has completed, we'll
2859 * get a NULL return here, as we clear the sched tag when
2860 * that happens. The request still remains valid, like always,
2861 * so we should be safe with just the NULL check.
2867 return __blk_mq_poll(hctx
, rq
);
2869 EXPORT_SYMBOL_GPL(blk_mq_poll
);
2871 void blk_mq_disable_hotplug(void)
2873 mutex_lock(&all_q_mutex
);
2876 void blk_mq_enable_hotplug(void)
2878 mutex_unlock(&all_q_mutex
);
2881 static int __init
blk_mq_init(void)
2883 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD
, "block/mq:dead", NULL
,
2884 blk_mq_hctx_notify_dead
);
2886 cpuhp_setup_state_nocalls(CPUHP_BLK_MQ_PREPARE
, "block/mq:prepare",
2887 blk_mq_queue_reinit_prepare
,
2888 blk_mq_queue_reinit_dead
);
2891 subsys_initcall(blk_mq_init
);