2 * Block multiqueue core code
4 * Copyright (C) 2013-2014 Jens Axboe
5 * Copyright (C) 2013-2014 Christoph Hellwig
7 #include <linux/kernel.h>
8 #include <linux/module.h>
9 #include <linux/backing-dev.h>
10 #include <linux/bio.h>
11 #include <linux/blkdev.h>
12 #include <linux/kmemleak.h>
14 #include <linux/init.h>
15 #include <linux/slab.h>
16 #include <linux/workqueue.h>
17 #include <linux/smp.h>
18 #include <linux/llist.h>
19 #include <linux/list_sort.h>
20 #include <linux/cpu.h>
21 #include <linux/cache.h>
22 #include <linux/sched/sysctl.h>
23 #include <linux/sched/topology.h>
24 #include <linux/sched/signal.h>
25 #include <linux/delay.h>
26 #include <linux/crash_dump.h>
27 #include <linux/prefetch.h>
29 #include <trace/events/block.h>
31 #include <linux/blk-mq.h>
34 #include "blk-mq-debugfs.h"
35 #include "blk-mq-tag.h"
38 #include "blk-mq-sched.h"
40 static void blk_mq_poll_stats_start(struct request_queue
*q
);
41 static void blk_mq_poll_stats_fn(struct blk_stat_callback
*cb
);
43 static int blk_mq_poll_stats_bkt(const struct request
*rq
)
45 int ddir
, bytes
, bucket
;
47 ddir
= rq_data_dir(rq
);
48 bytes
= blk_rq_bytes(rq
);
50 bucket
= ddir
+ 2*(ilog2(bytes
) - 9);
54 else if (bucket
>= BLK_MQ_POLL_STATS_BKTS
)
55 return ddir
+ BLK_MQ_POLL_STATS_BKTS
- 2;
61 * Check if any of the ctx's have pending work in this hardware queue
63 bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx
*hctx
)
65 return sbitmap_any_bit_set(&hctx
->ctx_map
) ||
66 !list_empty_careful(&hctx
->dispatch
) ||
67 blk_mq_sched_has_work(hctx
);
71 * Mark this ctx as having pending work in this hardware queue
73 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx
*hctx
,
74 struct blk_mq_ctx
*ctx
)
76 if (!sbitmap_test_bit(&hctx
->ctx_map
, ctx
->index_hw
))
77 sbitmap_set_bit(&hctx
->ctx_map
, ctx
->index_hw
);
80 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx
*hctx
,
81 struct blk_mq_ctx
*ctx
)
83 sbitmap_clear_bit(&hctx
->ctx_map
, ctx
->index_hw
);
87 struct hd_struct
*part
;
88 unsigned int *inflight
;
91 static void blk_mq_check_inflight(struct blk_mq_hw_ctx
*hctx
,
92 struct request
*rq
, void *priv
,
95 struct mq_inflight
*mi
= priv
;
97 if (test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
) &&
98 !test_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
)) {
100 * index[0] counts the specific partition that was asked
101 * for. index[1] counts the ones that are active on the
102 * whole device, so increment that if mi->part is indeed
103 * a partition, and not a whole device.
105 if (rq
->part
== mi
->part
)
107 if (mi
->part
->partno
)
112 void blk_mq_in_flight(struct request_queue
*q
, struct hd_struct
*part
,
113 unsigned int inflight
[2])
115 struct mq_inflight mi
= { .part
= part
, .inflight
= inflight
, };
117 inflight
[0] = inflight
[1] = 0;
118 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_inflight
, &mi
);
121 void blk_freeze_queue_start(struct request_queue
*q
)
125 freeze_depth
= atomic_inc_return(&q
->mq_freeze_depth
);
126 if (freeze_depth
== 1) {
127 percpu_ref_kill(&q
->q_usage_counter
);
128 blk_mq_run_hw_queues(q
, false);
131 EXPORT_SYMBOL_GPL(blk_freeze_queue_start
);
133 void blk_mq_freeze_queue_wait(struct request_queue
*q
)
135 wait_event(q
->mq_freeze_wq
, percpu_ref_is_zero(&q
->q_usage_counter
));
137 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait
);
139 int blk_mq_freeze_queue_wait_timeout(struct request_queue
*q
,
140 unsigned long timeout
)
142 return wait_event_timeout(q
->mq_freeze_wq
,
143 percpu_ref_is_zero(&q
->q_usage_counter
),
146 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout
);
149 * Guarantee no request is in use, so we can change any data structure of
150 * the queue afterward.
152 void blk_freeze_queue(struct request_queue
*q
)
155 * In the !blk_mq case we are only calling this to kill the
156 * q_usage_counter, otherwise this increases the freeze depth
157 * and waits for it to return to zero. For this reason there is
158 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
159 * exported to drivers as the only user for unfreeze is blk_mq.
161 blk_freeze_queue_start(q
);
162 blk_mq_freeze_queue_wait(q
);
165 void blk_mq_freeze_queue(struct request_queue
*q
)
168 * ...just an alias to keep freeze and unfreeze actions balanced
169 * in the blk_mq_* namespace
173 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue
);
175 void blk_mq_unfreeze_queue(struct request_queue
*q
)
179 freeze_depth
= atomic_dec_return(&q
->mq_freeze_depth
);
180 WARN_ON_ONCE(freeze_depth
< 0);
182 percpu_ref_reinit(&q
->q_usage_counter
);
183 wake_up_all(&q
->mq_freeze_wq
);
186 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue
);
189 * FIXME: replace the scsi_internal_device_*block_nowait() calls in the
190 * mpt3sas driver such that this function can be removed.
192 void blk_mq_quiesce_queue_nowait(struct request_queue
*q
)
196 spin_lock_irqsave(q
->queue_lock
, flags
);
197 queue_flag_set(QUEUE_FLAG_QUIESCED
, q
);
198 spin_unlock_irqrestore(q
->queue_lock
, flags
);
200 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait
);
203 * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished
206 * Note: this function does not prevent that the struct request end_io()
207 * callback function is invoked. Once this function is returned, we make
208 * sure no dispatch can happen until the queue is unquiesced via
209 * blk_mq_unquiesce_queue().
211 void blk_mq_quiesce_queue(struct request_queue
*q
)
213 struct blk_mq_hw_ctx
*hctx
;
217 blk_mq_quiesce_queue_nowait(q
);
219 queue_for_each_hw_ctx(q
, hctx
, i
) {
220 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
221 synchronize_srcu(hctx
->queue_rq_srcu
);
228 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue
);
231 * blk_mq_unquiesce_queue() - counterpart of blk_mq_quiesce_queue()
234 * This function recovers queue into the state before quiescing
235 * which is done by blk_mq_quiesce_queue.
237 void blk_mq_unquiesce_queue(struct request_queue
*q
)
241 spin_lock_irqsave(q
->queue_lock
, flags
);
242 queue_flag_clear(QUEUE_FLAG_QUIESCED
, q
);
243 spin_unlock_irqrestore(q
->queue_lock
, flags
);
245 /* dispatch requests which are inserted during quiescing */
246 blk_mq_run_hw_queues(q
, true);
248 EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue
);
250 void blk_mq_wake_waiters(struct request_queue
*q
)
252 struct blk_mq_hw_ctx
*hctx
;
255 queue_for_each_hw_ctx(q
, hctx
, i
)
256 if (blk_mq_hw_queue_mapped(hctx
))
257 blk_mq_tag_wakeup_all(hctx
->tags
, true);
260 * If we are called because the queue has now been marked as
261 * dying, we need to ensure that processes currently waiting on
262 * the queue are notified as well.
264 wake_up_all(&q
->mq_freeze_wq
);
267 bool blk_mq_can_queue(struct blk_mq_hw_ctx
*hctx
)
269 return blk_mq_has_free_tags(hctx
->tags
);
271 EXPORT_SYMBOL(blk_mq_can_queue
);
273 static struct request
*blk_mq_rq_ctx_init(struct blk_mq_alloc_data
*data
,
274 unsigned int tag
, unsigned int op
)
276 struct blk_mq_tags
*tags
= blk_mq_tags_from_data(data
);
277 struct request
*rq
= tags
->static_rqs
[tag
];
281 if (data
->flags
& BLK_MQ_REQ_INTERNAL
) {
283 rq
->internal_tag
= tag
;
285 if (blk_mq_tag_busy(data
->hctx
)) {
286 rq
->rq_flags
= RQF_MQ_INFLIGHT
;
287 atomic_inc(&data
->hctx
->nr_active
);
290 rq
->internal_tag
= -1;
291 data
->hctx
->tags
->rqs
[rq
->tag
] = rq
;
294 INIT_LIST_HEAD(&rq
->queuelist
);
295 /* csd/requeue_work/fifo_time is initialized before use */
297 rq
->mq_ctx
= data
->ctx
;
299 if (blk_queue_io_stat(data
->q
))
300 rq
->rq_flags
|= RQF_IO_STAT
;
301 /* do not touch atomic flags, it needs atomic ops against the timer */
303 INIT_HLIST_NODE(&rq
->hash
);
304 RB_CLEAR_NODE(&rq
->rb_node
);
307 rq
->start_time
= jiffies
;
308 #ifdef CONFIG_BLK_CGROUP
310 set_start_time_ns(rq
);
311 rq
->io_start_time_ns
= 0;
313 rq
->nr_phys_segments
= 0;
314 #if defined(CONFIG_BLK_DEV_INTEGRITY)
315 rq
->nr_integrity_segments
= 0;
318 /* tag was already set */
321 INIT_LIST_HEAD(&rq
->timeout_list
);
325 rq
->end_io_data
= NULL
;
328 data
->ctx
->rq_dispatched
[op_is_sync(op
)]++;
332 static struct request
*blk_mq_get_request(struct request_queue
*q
,
333 struct bio
*bio
, unsigned int op
,
334 struct blk_mq_alloc_data
*data
)
336 struct elevator_queue
*e
= q
->elevator
;
339 struct blk_mq_ctx
*local_ctx
= NULL
;
341 blk_queue_enter_live(q
);
343 if (likely(!data
->ctx
))
344 data
->ctx
= local_ctx
= blk_mq_get_ctx(q
);
345 if (likely(!data
->hctx
))
346 data
->hctx
= blk_mq_map_queue(q
, data
->ctx
->cpu
);
348 data
->flags
|= BLK_MQ_REQ_NOWAIT
;
351 data
->flags
|= BLK_MQ_REQ_INTERNAL
;
354 * Flush requests are special and go directly to the
357 if (!op_is_flush(op
) && e
->type
->ops
.mq
.limit_depth
)
358 e
->type
->ops
.mq
.limit_depth(op
, data
);
361 tag
= blk_mq_get_tag(data
);
362 if (tag
== BLK_MQ_TAG_FAIL
) {
364 blk_mq_put_ctx(local_ctx
);
371 rq
= blk_mq_rq_ctx_init(data
, tag
, op
);
372 if (!op_is_flush(op
)) {
374 if (e
&& e
->type
->ops
.mq
.prepare_request
) {
375 if (e
->type
->icq_cache
&& rq_ioc(bio
))
376 blk_mq_sched_assign_ioc(rq
, bio
);
378 e
->type
->ops
.mq
.prepare_request(rq
, bio
);
379 rq
->rq_flags
|= RQF_ELVPRIV
;
382 data
->hctx
->queued
++;
386 struct request
*blk_mq_alloc_request(struct request_queue
*q
, unsigned int op
,
389 struct blk_mq_alloc_data alloc_data
= { .flags
= flags
};
393 ret
= blk_queue_enter(q
, flags
& BLK_MQ_REQ_NOWAIT
);
397 rq
= blk_mq_get_request(q
, NULL
, op
, &alloc_data
);
401 return ERR_PTR(-EWOULDBLOCK
);
403 blk_mq_put_ctx(alloc_data
.ctx
);
406 rq
->__sector
= (sector_t
) -1;
407 rq
->bio
= rq
->biotail
= NULL
;
410 EXPORT_SYMBOL(blk_mq_alloc_request
);
412 struct request
*blk_mq_alloc_request_hctx(struct request_queue
*q
,
413 unsigned int op
, unsigned int flags
, unsigned int hctx_idx
)
415 struct blk_mq_alloc_data alloc_data
= { .flags
= flags
};
421 * If the tag allocator sleeps we could get an allocation for a
422 * different hardware context. No need to complicate the low level
423 * allocator for this for the rare use case of a command tied to
426 if (WARN_ON_ONCE(!(flags
& BLK_MQ_REQ_NOWAIT
)))
427 return ERR_PTR(-EINVAL
);
429 if (hctx_idx
>= q
->nr_hw_queues
)
430 return ERR_PTR(-EIO
);
432 ret
= blk_queue_enter(q
, true);
437 * Check if the hardware context is actually mapped to anything.
438 * If not tell the caller that it should skip this queue.
440 alloc_data
.hctx
= q
->queue_hw_ctx
[hctx_idx
];
441 if (!blk_mq_hw_queue_mapped(alloc_data
.hctx
)) {
443 return ERR_PTR(-EXDEV
);
445 cpu
= cpumask_first(alloc_data
.hctx
->cpumask
);
446 alloc_data
.ctx
= __blk_mq_get_ctx(q
, cpu
);
448 rq
= blk_mq_get_request(q
, NULL
, op
, &alloc_data
);
452 return ERR_PTR(-EWOULDBLOCK
);
456 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx
);
458 void blk_mq_free_request(struct request
*rq
)
460 struct request_queue
*q
= rq
->q
;
461 struct elevator_queue
*e
= q
->elevator
;
462 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
463 struct blk_mq_hw_ctx
*hctx
= blk_mq_map_queue(q
, ctx
->cpu
);
464 const int sched_tag
= rq
->internal_tag
;
466 if (rq
->rq_flags
& RQF_ELVPRIV
) {
467 if (e
&& e
->type
->ops
.mq
.finish_request
)
468 e
->type
->ops
.mq
.finish_request(rq
);
470 put_io_context(rq
->elv
.icq
->ioc
);
475 ctx
->rq_completed
[rq_is_sync(rq
)]++;
476 if (rq
->rq_flags
& RQF_MQ_INFLIGHT
)
477 atomic_dec(&hctx
->nr_active
);
479 if (unlikely(laptop_mode
&& !blk_rq_is_passthrough(rq
)))
480 laptop_io_completion(q
->backing_dev_info
);
482 wbt_done(q
->rq_wb
, &rq
->issue_stat
);
485 blk_put_rl(blk_rq_rl(rq
));
487 clear_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
488 clear_bit(REQ_ATOM_POLL_SLEPT
, &rq
->atomic_flags
);
490 blk_mq_put_tag(hctx
, hctx
->tags
, ctx
, rq
->tag
);
492 blk_mq_put_tag(hctx
, hctx
->sched_tags
, ctx
, sched_tag
);
493 blk_mq_sched_restart(hctx
);
496 EXPORT_SYMBOL_GPL(blk_mq_free_request
);
498 inline void __blk_mq_end_request(struct request
*rq
, blk_status_t error
)
500 blk_account_io_done(rq
);
503 wbt_done(rq
->q
->rq_wb
, &rq
->issue_stat
);
504 rq
->end_io(rq
, error
);
506 if (unlikely(blk_bidi_rq(rq
)))
507 blk_mq_free_request(rq
->next_rq
);
508 blk_mq_free_request(rq
);
511 EXPORT_SYMBOL(__blk_mq_end_request
);
513 void blk_mq_end_request(struct request
*rq
, blk_status_t error
)
515 if (blk_update_request(rq
, error
, blk_rq_bytes(rq
)))
517 __blk_mq_end_request(rq
, error
);
519 EXPORT_SYMBOL(blk_mq_end_request
);
521 static void __blk_mq_complete_request_remote(void *data
)
523 struct request
*rq
= data
;
525 rq
->q
->softirq_done_fn(rq
);
528 static void __blk_mq_complete_request(struct request
*rq
)
530 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
534 if (rq
->internal_tag
!= -1)
535 blk_mq_sched_completed_request(rq
);
536 if (rq
->rq_flags
& RQF_STATS
) {
537 blk_mq_poll_stats_start(rq
->q
);
541 if (!test_bit(QUEUE_FLAG_SAME_COMP
, &rq
->q
->queue_flags
)) {
542 rq
->q
->softirq_done_fn(rq
);
547 if (!test_bit(QUEUE_FLAG_SAME_FORCE
, &rq
->q
->queue_flags
))
548 shared
= cpus_share_cache(cpu
, ctx
->cpu
);
550 if (cpu
!= ctx
->cpu
&& !shared
&& cpu_online(ctx
->cpu
)) {
551 rq
->csd
.func
= __blk_mq_complete_request_remote
;
554 smp_call_function_single_async(ctx
->cpu
, &rq
->csd
);
556 rq
->q
->softirq_done_fn(rq
);
562 * blk_mq_complete_request - end I/O on a request
563 * @rq: the request being processed
566 * Ends all I/O on a request. It does not handle partial completions.
567 * The actual completion happens out-of-order, through a IPI handler.
569 void blk_mq_complete_request(struct request
*rq
)
571 struct request_queue
*q
= rq
->q
;
573 if (unlikely(blk_should_fake_timeout(q
)))
575 if (!blk_mark_rq_complete(rq
))
576 __blk_mq_complete_request(rq
);
578 EXPORT_SYMBOL(blk_mq_complete_request
);
580 int blk_mq_request_started(struct request
*rq
)
582 return test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
584 EXPORT_SYMBOL_GPL(blk_mq_request_started
);
586 void blk_mq_start_request(struct request
*rq
)
588 struct request_queue
*q
= rq
->q
;
590 blk_mq_sched_started_request(rq
);
592 trace_block_rq_issue(q
, rq
);
594 if (test_bit(QUEUE_FLAG_STATS
, &q
->queue_flags
)) {
595 blk_stat_set_issue(&rq
->issue_stat
, blk_rq_sectors(rq
));
596 rq
->rq_flags
|= RQF_STATS
;
597 wbt_issue(q
->rq_wb
, &rq
->issue_stat
);
602 WARN_ON_ONCE(test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
));
605 * Mark us as started and clear complete. Complete might have been
606 * set if requeue raced with timeout, which then marked it as
607 * complete. So be sure to clear complete again when we start
608 * the request, otherwise we'll ignore the completion event.
610 * Ensure that ->deadline is visible before we set STARTED, such that
611 * blk_mq_check_expired() is guaranteed to observe our ->deadline when
612 * it observes STARTED.
615 set_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
616 if (test_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
)) {
618 * Coherence order guarantees these consecutive stores to a
619 * single variable propagate in the specified order. Thus the
620 * clear_bit() is ordered _after_ the set bit. See
621 * blk_mq_check_expired().
623 * (the bits must be part of the same byte for this to be
626 clear_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
);
629 if (q
->dma_drain_size
&& blk_rq_bytes(rq
)) {
631 * Make sure space for the drain appears. We know we can do
632 * this because max_hw_segments has been adjusted to be one
633 * fewer than the device can handle.
635 rq
->nr_phys_segments
++;
638 EXPORT_SYMBOL(blk_mq_start_request
);
641 * When we reach here because queue is busy, REQ_ATOM_COMPLETE
642 * flag isn't set yet, so there may be race with timeout handler,
643 * but given rq->deadline is just set in .queue_rq() under
644 * this situation, the race won't be possible in reality because
645 * rq->timeout should be set as big enough to cover the window
646 * between blk_mq_start_request() called from .queue_rq() and
647 * clearing REQ_ATOM_STARTED here.
649 static void __blk_mq_requeue_request(struct request
*rq
)
651 struct request_queue
*q
= rq
->q
;
653 trace_block_rq_requeue(q
, rq
);
654 wbt_requeue(q
->rq_wb
, &rq
->issue_stat
);
655 blk_mq_sched_requeue_request(rq
);
657 if (test_and_clear_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
)) {
658 if (q
->dma_drain_size
&& blk_rq_bytes(rq
))
659 rq
->nr_phys_segments
--;
663 void blk_mq_requeue_request(struct request
*rq
, bool kick_requeue_list
)
665 __blk_mq_requeue_request(rq
);
667 BUG_ON(blk_queued_rq(rq
));
668 blk_mq_add_to_requeue_list(rq
, true, kick_requeue_list
);
670 EXPORT_SYMBOL(blk_mq_requeue_request
);
672 static void blk_mq_requeue_work(struct work_struct
*work
)
674 struct request_queue
*q
=
675 container_of(work
, struct request_queue
, requeue_work
.work
);
677 struct request
*rq
, *next
;
679 spin_lock_irq(&q
->requeue_lock
);
680 list_splice_init(&q
->requeue_list
, &rq_list
);
681 spin_unlock_irq(&q
->requeue_lock
);
683 list_for_each_entry_safe(rq
, next
, &rq_list
, queuelist
) {
684 if (!(rq
->rq_flags
& RQF_SOFTBARRIER
))
687 rq
->rq_flags
&= ~RQF_SOFTBARRIER
;
688 list_del_init(&rq
->queuelist
);
689 blk_mq_sched_insert_request(rq
, true, false, false, true);
692 while (!list_empty(&rq_list
)) {
693 rq
= list_entry(rq_list
.next
, struct request
, queuelist
);
694 list_del_init(&rq
->queuelist
);
695 blk_mq_sched_insert_request(rq
, false, false, false, true);
698 blk_mq_run_hw_queues(q
, false);
701 void blk_mq_add_to_requeue_list(struct request
*rq
, bool at_head
,
702 bool kick_requeue_list
)
704 struct request_queue
*q
= rq
->q
;
708 * We abuse this flag that is otherwise used by the I/O scheduler to
709 * request head insertation from the workqueue.
711 BUG_ON(rq
->rq_flags
& RQF_SOFTBARRIER
);
713 spin_lock_irqsave(&q
->requeue_lock
, flags
);
715 rq
->rq_flags
|= RQF_SOFTBARRIER
;
716 list_add(&rq
->queuelist
, &q
->requeue_list
);
718 list_add_tail(&rq
->queuelist
, &q
->requeue_list
);
720 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
722 if (kick_requeue_list
)
723 blk_mq_kick_requeue_list(q
);
725 EXPORT_SYMBOL(blk_mq_add_to_requeue_list
);
727 void blk_mq_kick_requeue_list(struct request_queue
*q
)
729 kblockd_schedule_delayed_work(&q
->requeue_work
, 0);
731 EXPORT_SYMBOL(blk_mq_kick_requeue_list
);
733 void blk_mq_delay_kick_requeue_list(struct request_queue
*q
,
736 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND
, &q
->requeue_work
,
737 msecs_to_jiffies(msecs
));
739 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list
);
741 struct request
*blk_mq_tag_to_rq(struct blk_mq_tags
*tags
, unsigned int tag
)
743 if (tag
< tags
->nr_tags
) {
744 prefetch(tags
->rqs
[tag
]);
745 return tags
->rqs
[tag
];
750 EXPORT_SYMBOL(blk_mq_tag_to_rq
);
752 struct blk_mq_timeout_data
{
754 unsigned int next_set
;
757 void blk_mq_rq_timed_out(struct request
*req
, bool reserved
)
759 const struct blk_mq_ops
*ops
= req
->q
->mq_ops
;
760 enum blk_eh_timer_return ret
= BLK_EH_RESET_TIMER
;
763 * We know that complete is set at this point. If STARTED isn't set
764 * anymore, then the request isn't active and the "timeout" should
765 * just be ignored. This can happen due to the bitflag ordering.
766 * Timeout first checks if STARTED is set, and if it is, assumes
767 * the request is active. But if we race with completion, then
768 * both flags will get cleared. So check here again, and ignore
769 * a timeout event with a request that isn't active.
771 if (!test_bit(REQ_ATOM_STARTED
, &req
->atomic_flags
))
775 ret
= ops
->timeout(req
, reserved
);
779 __blk_mq_complete_request(req
);
781 case BLK_EH_RESET_TIMER
:
783 blk_clear_rq_complete(req
);
785 case BLK_EH_NOT_HANDLED
:
788 printk(KERN_ERR
"block: bad eh return: %d\n", ret
);
793 static void blk_mq_check_expired(struct blk_mq_hw_ctx
*hctx
,
794 struct request
*rq
, void *priv
, bool reserved
)
796 struct blk_mq_timeout_data
*data
= priv
;
797 unsigned long deadline
;
799 if (!test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
))
803 * Ensures that if we see STARTED we must also see our
804 * up-to-date deadline, see blk_mq_start_request().
808 deadline
= READ_ONCE(rq
->deadline
);
811 * The rq being checked may have been freed and reallocated
812 * out already here, we avoid this race by checking rq->deadline
813 * and REQ_ATOM_COMPLETE flag together:
815 * - if rq->deadline is observed as new value because of
816 * reusing, the rq won't be timed out because of timing.
817 * - if rq->deadline is observed as previous value,
818 * REQ_ATOM_COMPLETE flag won't be cleared in reuse path
819 * because we put a barrier between setting rq->deadline
820 * and clearing the flag in blk_mq_start_request(), so
821 * this rq won't be timed out too.
823 if (time_after_eq(jiffies
, deadline
)) {
824 if (!blk_mark_rq_complete(rq
)) {
826 * Again coherence order ensures that consecutive reads
827 * from the same variable must be in that order. This
828 * ensures that if we see COMPLETE clear, we must then
829 * see STARTED set and we'll ignore this timeout.
831 * (There's also the MB implied by the test_and_clear())
833 blk_mq_rq_timed_out(rq
, reserved
);
835 } else if (!data
->next_set
|| time_after(data
->next
, deadline
)) {
836 data
->next
= deadline
;
841 static void blk_mq_timeout_work(struct work_struct
*work
)
843 struct request_queue
*q
=
844 container_of(work
, struct request_queue
, timeout_work
);
845 struct blk_mq_timeout_data data
= {
851 /* A deadlock might occur if a request is stuck requiring a
852 * timeout at the same time a queue freeze is waiting
853 * completion, since the timeout code would not be able to
854 * acquire the queue reference here.
856 * That's why we don't use blk_queue_enter here; instead, we use
857 * percpu_ref_tryget directly, because we need to be able to
858 * obtain a reference even in the short window between the queue
859 * starting to freeze, by dropping the first reference in
860 * blk_freeze_queue_start, and the moment the last request is
861 * consumed, marked by the instant q_usage_counter reaches
864 if (!percpu_ref_tryget(&q
->q_usage_counter
))
867 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_expired
, &data
);
870 data
.next
= blk_rq_timeout(round_jiffies_up(data
.next
));
871 mod_timer(&q
->timeout
, data
.next
);
873 struct blk_mq_hw_ctx
*hctx
;
875 queue_for_each_hw_ctx(q
, hctx
, i
) {
876 /* the hctx may be unmapped, so check it here */
877 if (blk_mq_hw_queue_mapped(hctx
))
878 blk_mq_tag_idle(hctx
);
884 struct flush_busy_ctx_data
{
885 struct blk_mq_hw_ctx
*hctx
;
886 struct list_head
*list
;
889 static bool flush_busy_ctx(struct sbitmap
*sb
, unsigned int bitnr
, void *data
)
891 struct flush_busy_ctx_data
*flush_data
= data
;
892 struct blk_mq_hw_ctx
*hctx
= flush_data
->hctx
;
893 struct blk_mq_ctx
*ctx
= hctx
->ctxs
[bitnr
];
895 sbitmap_clear_bit(sb
, bitnr
);
896 spin_lock(&ctx
->lock
);
897 list_splice_tail_init(&ctx
->rq_list
, flush_data
->list
);
898 spin_unlock(&ctx
->lock
);
903 * Process software queues that have been marked busy, splicing them
904 * to the for-dispatch
906 void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx
*hctx
, struct list_head
*list
)
908 struct flush_busy_ctx_data data
= {
913 sbitmap_for_each_set(&hctx
->ctx_map
, flush_busy_ctx
, &data
);
915 EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs
);
917 struct dispatch_rq_data
{
918 struct blk_mq_hw_ctx
*hctx
;
922 static bool dispatch_rq_from_ctx(struct sbitmap
*sb
, unsigned int bitnr
,
925 struct dispatch_rq_data
*dispatch_data
= data
;
926 struct blk_mq_hw_ctx
*hctx
= dispatch_data
->hctx
;
927 struct blk_mq_ctx
*ctx
= hctx
->ctxs
[bitnr
];
929 spin_lock(&ctx
->lock
);
930 if (unlikely(!list_empty(&ctx
->rq_list
))) {
931 dispatch_data
->rq
= list_entry_rq(ctx
->rq_list
.next
);
932 list_del_init(&dispatch_data
->rq
->queuelist
);
933 if (list_empty(&ctx
->rq_list
))
934 sbitmap_clear_bit(sb
, bitnr
);
936 spin_unlock(&ctx
->lock
);
938 return !dispatch_data
->rq
;
941 struct request
*blk_mq_dequeue_from_ctx(struct blk_mq_hw_ctx
*hctx
,
942 struct blk_mq_ctx
*start
)
944 unsigned off
= start
? start
->index_hw
: 0;
945 struct dispatch_rq_data data
= {
950 __sbitmap_for_each_set(&hctx
->ctx_map
, off
,
951 dispatch_rq_from_ctx
, &data
);
956 static inline unsigned int queued_to_index(unsigned int queued
)
961 return min(BLK_MQ_MAX_DISPATCH_ORDER
- 1, ilog2(queued
) + 1);
964 bool blk_mq_get_driver_tag(struct request
*rq
, struct blk_mq_hw_ctx
**hctx
,
967 struct blk_mq_alloc_data data
= {
969 .hctx
= blk_mq_map_queue(rq
->q
, rq
->mq_ctx
->cpu
),
970 .flags
= wait
? 0 : BLK_MQ_REQ_NOWAIT
,
973 might_sleep_if(wait
);
978 if (blk_mq_tag_is_reserved(data
.hctx
->sched_tags
, rq
->internal_tag
))
979 data
.flags
|= BLK_MQ_REQ_RESERVED
;
981 rq
->tag
= blk_mq_get_tag(&data
);
983 if (blk_mq_tag_busy(data
.hctx
)) {
984 rq
->rq_flags
|= RQF_MQ_INFLIGHT
;
985 atomic_inc(&data
.hctx
->nr_active
);
987 data
.hctx
->tags
->rqs
[rq
->tag
] = rq
;
993 return rq
->tag
!= -1;
996 static void __blk_mq_put_driver_tag(struct blk_mq_hw_ctx
*hctx
,
999 blk_mq_put_tag(hctx
, hctx
->tags
, rq
->mq_ctx
, rq
->tag
);
1002 if (rq
->rq_flags
& RQF_MQ_INFLIGHT
) {
1003 rq
->rq_flags
&= ~RQF_MQ_INFLIGHT
;
1004 atomic_dec(&hctx
->nr_active
);
1008 static void blk_mq_put_driver_tag_hctx(struct blk_mq_hw_ctx
*hctx
,
1011 if (rq
->tag
== -1 || rq
->internal_tag
== -1)
1014 __blk_mq_put_driver_tag(hctx
, rq
);
1017 static void blk_mq_put_driver_tag(struct request
*rq
)
1019 struct blk_mq_hw_ctx
*hctx
;
1021 if (rq
->tag
== -1 || rq
->internal_tag
== -1)
1024 hctx
= blk_mq_map_queue(rq
->q
, rq
->mq_ctx
->cpu
);
1025 __blk_mq_put_driver_tag(hctx
, rq
);
1029 * If we fail getting a driver tag because all the driver tags are already
1030 * assigned and on the dispatch list, BUT the first entry does not have a
1031 * tag, then we could deadlock. For that case, move entries with assigned
1032 * driver tags to the front, leaving the set of tagged requests in the
1033 * same order, and the untagged set in the same order.
1035 static bool reorder_tags_to_front(struct list_head
*list
)
1037 struct request
*rq
, *tmp
, *first
= NULL
;
1039 list_for_each_entry_safe_reverse(rq
, tmp
, list
, queuelist
) {
1042 if (rq
->tag
!= -1) {
1043 list_move(&rq
->queuelist
, list
);
1049 return first
!= NULL
;
1052 static int blk_mq_dispatch_wake(wait_queue_entry_t
*wait
, unsigned mode
, int flags
,
1055 struct blk_mq_hw_ctx
*hctx
;
1057 hctx
= container_of(wait
, struct blk_mq_hw_ctx
, dispatch_wait
);
1059 list_del(&wait
->entry
);
1060 clear_bit_unlock(BLK_MQ_S_TAG_WAITING
, &hctx
->state
);
1061 blk_mq_run_hw_queue(hctx
, true);
1065 static bool blk_mq_dispatch_wait_add(struct blk_mq_hw_ctx
*hctx
)
1067 struct sbq_wait_state
*ws
;
1070 * The TAG_WAITING bit serves as a lock protecting hctx->dispatch_wait.
1071 * The thread which wins the race to grab this bit adds the hardware
1072 * queue to the wait queue.
1074 if (test_bit(BLK_MQ_S_TAG_WAITING
, &hctx
->state
) ||
1075 test_and_set_bit_lock(BLK_MQ_S_TAG_WAITING
, &hctx
->state
))
1078 init_waitqueue_func_entry(&hctx
->dispatch_wait
, blk_mq_dispatch_wake
);
1079 ws
= bt_wait_ptr(&hctx
->tags
->bitmap_tags
, hctx
);
1082 * As soon as this returns, it's no longer safe to fiddle with
1083 * hctx->dispatch_wait, since a completion can wake up the wait queue
1084 * and unlock the bit.
1086 add_wait_queue(&ws
->wait
, &hctx
->dispatch_wait
);
1090 bool blk_mq_dispatch_rq_list(struct request_queue
*q
, struct list_head
*list
,
1093 struct blk_mq_hw_ctx
*hctx
;
1097 if (list_empty(list
))
1100 WARN_ON(!list_is_singular(list
) && got_budget
);
1103 * Now process all the entries, sending them to the driver.
1105 errors
= queued
= 0;
1107 struct blk_mq_queue_data bd
;
1110 rq
= list_first_entry(list
, struct request
, queuelist
);
1111 if (!blk_mq_get_driver_tag(rq
, &hctx
, false)) {
1112 if (!queued
&& reorder_tags_to_front(list
))
1116 * The initial allocation attempt failed, so we need to
1117 * rerun the hardware queue when a tag is freed.
1119 if (!blk_mq_dispatch_wait_add(hctx
)) {
1121 blk_mq_put_dispatch_budget(hctx
);
1126 * It's possible that a tag was freed in the window
1127 * between the allocation failure and adding the
1128 * hardware queue to the wait queue.
1130 if (!blk_mq_get_driver_tag(rq
, &hctx
, false)) {
1132 blk_mq_put_dispatch_budget(hctx
);
1138 ret
= blk_mq_get_dispatch_budget(hctx
);
1139 if (ret
== BLK_STS_RESOURCE
)
1141 if (ret
!= BLK_STS_OK
)
1145 list_del_init(&rq
->queuelist
);
1150 * Flag last if we have no more requests, or if we have more
1151 * but can't assign a driver tag to it.
1153 if (list_empty(list
))
1156 struct request
*nxt
;
1158 nxt
= list_first_entry(list
, struct request
, queuelist
);
1159 bd
.last
= !blk_mq_get_driver_tag(nxt
, NULL
, false);
1162 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1163 if (ret
== BLK_STS_RESOURCE
) {
1164 blk_mq_put_driver_tag_hctx(hctx
, rq
);
1165 list_add(&rq
->queuelist
, list
);
1166 __blk_mq_requeue_request(rq
);
1171 if (unlikely(ret
!= BLK_STS_OK
)) {
1173 blk_mq_end_request(rq
, BLK_STS_IOERR
);
1178 } while (!list_empty(list
));
1180 hctx
->dispatched
[queued_to_index(queued
)]++;
1183 * Any items that need requeuing? Stuff them into hctx->dispatch,
1184 * that is where we will continue on next queue run.
1186 if (!list_empty(list
)) {
1188 * If an I/O scheduler has been configured and we got a driver
1189 * tag for the next request already, free it again.
1191 rq
= list_first_entry(list
, struct request
, queuelist
);
1192 blk_mq_put_driver_tag(rq
);
1194 spin_lock(&hctx
->lock
);
1195 list_splice_init(list
, &hctx
->dispatch
);
1196 spin_unlock(&hctx
->lock
);
1199 * If SCHED_RESTART was set by the caller of this function and
1200 * it is no longer set that means that it was cleared by another
1201 * thread and hence that a queue rerun is needed.
1203 * If TAG_WAITING is set that means that an I/O scheduler has
1204 * been configured and another thread is waiting for a driver
1205 * tag. To guarantee fairness, do not rerun this hardware queue
1206 * but let the other thread grab the driver tag.
1208 * If no I/O scheduler has been configured it is possible that
1209 * the hardware queue got stopped and restarted before requests
1210 * were pushed back onto the dispatch list. Rerun the queue to
1211 * avoid starvation. Notes:
1212 * - blk_mq_run_hw_queue() checks whether or not a queue has
1213 * been stopped before rerunning a queue.
1214 * - Some but not all block drivers stop a queue before
1215 * returning BLK_STS_RESOURCE. Two exceptions are scsi-mq
1218 if (!blk_mq_sched_needs_restart(hctx
) &&
1219 !test_bit(BLK_MQ_S_TAG_WAITING
, &hctx
->state
))
1220 blk_mq_run_hw_queue(hctx
, true);
1223 return (queued
+ errors
) != 0;
1226 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1232 * We should be running this queue from one of the CPUs that
1235 WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx
->cpumask
) &&
1236 cpu_online(hctx
->next_cpu
));
1239 * We can't run the queue inline with ints disabled. Ensure that
1240 * we catch bad users of this early.
1242 WARN_ON_ONCE(in_interrupt());
1244 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1246 run_queue
= blk_mq_sched_dispatch_requests(hctx
);
1251 srcu_idx
= srcu_read_lock(hctx
->queue_rq_srcu
);
1252 run_queue
= blk_mq_sched_dispatch_requests(hctx
);
1253 srcu_read_unlock(hctx
->queue_rq_srcu
, srcu_idx
);
1257 blk_mq_run_hw_queue(hctx
, true);
1261 * It'd be great if the workqueue API had a way to pass
1262 * in a mask and had some smarts for more clever placement.
1263 * For now we just round-robin here, switching for every
1264 * BLK_MQ_CPU_WORK_BATCH queued items.
1266 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx
*hctx
)
1268 if (hctx
->queue
->nr_hw_queues
== 1)
1269 return WORK_CPU_UNBOUND
;
1271 if (--hctx
->next_cpu_batch
<= 0) {
1274 next_cpu
= cpumask_next(hctx
->next_cpu
, hctx
->cpumask
);
1275 if (next_cpu
>= nr_cpu_ids
)
1276 next_cpu
= cpumask_first(hctx
->cpumask
);
1278 hctx
->next_cpu
= next_cpu
;
1279 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
1282 return hctx
->next_cpu
;
1285 static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
,
1286 unsigned long msecs
)
1288 if (WARN_ON_ONCE(!blk_mq_hw_queue_mapped(hctx
)))
1291 if (unlikely(blk_mq_hctx_stopped(hctx
)))
1294 if (!async
&& !(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1295 int cpu
= get_cpu();
1296 if (cpumask_test_cpu(cpu
, hctx
->cpumask
)) {
1297 __blk_mq_run_hw_queue(hctx
);
1305 kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx
),
1307 msecs_to_jiffies(msecs
));
1310 void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, unsigned long msecs
)
1312 __blk_mq_delay_run_hw_queue(hctx
, true, msecs
);
1314 EXPORT_SYMBOL(blk_mq_delay_run_hw_queue
);
1316 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1318 __blk_mq_delay_run_hw_queue(hctx
, async
, 0);
1320 EXPORT_SYMBOL(blk_mq_run_hw_queue
);
1322 void blk_mq_run_hw_queues(struct request_queue
*q
, bool async
)
1324 struct blk_mq_hw_ctx
*hctx
;
1327 queue_for_each_hw_ctx(q
, hctx
, i
) {
1328 if (!blk_mq_hctx_has_pending(hctx
) ||
1329 blk_mq_hctx_stopped(hctx
))
1332 blk_mq_run_hw_queue(hctx
, async
);
1335 EXPORT_SYMBOL(blk_mq_run_hw_queues
);
1338 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1339 * @q: request queue.
1341 * The caller is responsible for serializing this function against
1342 * blk_mq_{start,stop}_hw_queue().
1344 bool blk_mq_queue_stopped(struct request_queue
*q
)
1346 struct blk_mq_hw_ctx
*hctx
;
1349 queue_for_each_hw_ctx(q
, hctx
, i
)
1350 if (blk_mq_hctx_stopped(hctx
))
1355 EXPORT_SYMBOL(blk_mq_queue_stopped
);
1358 * This function is often used for pausing .queue_rq() by driver when
1359 * there isn't enough resource or some conditions aren't satisfied, and
1360 * BLK_STS_RESOURCE is usually returned.
1362 * We do not guarantee that dispatch can be drained or blocked
1363 * after blk_mq_stop_hw_queue() returns. Please use
1364 * blk_mq_quiesce_queue() for that requirement.
1366 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1368 cancel_delayed_work(&hctx
->run_work
);
1370 set_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1372 EXPORT_SYMBOL(blk_mq_stop_hw_queue
);
1375 * This function is often used for pausing .queue_rq() by driver when
1376 * there isn't enough resource or some conditions aren't satisfied, and
1377 * BLK_STS_RESOURCE is usually returned.
1379 * We do not guarantee that dispatch can be drained or blocked
1380 * after blk_mq_stop_hw_queues() returns. Please use
1381 * blk_mq_quiesce_queue() for that requirement.
1383 void blk_mq_stop_hw_queues(struct request_queue
*q
)
1385 struct blk_mq_hw_ctx
*hctx
;
1388 queue_for_each_hw_ctx(q
, hctx
, i
)
1389 blk_mq_stop_hw_queue(hctx
);
1391 EXPORT_SYMBOL(blk_mq_stop_hw_queues
);
1393 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1395 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1397 blk_mq_run_hw_queue(hctx
, false);
1399 EXPORT_SYMBOL(blk_mq_start_hw_queue
);
1401 void blk_mq_start_hw_queues(struct request_queue
*q
)
1403 struct blk_mq_hw_ctx
*hctx
;
1406 queue_for_each_hw_ctx(q
, hctx
, i
)
1407 blk_mq_start_hw_queue(hctx
);
1409 EXPORT_SYMBOL(blk_mq_start_hw_queues
);
1411 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1413 if (!blk_mq_hctx_stopped(hctx
))
1416 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1417 blk_mq_run_hw_queue(hctx
, async
);
1419 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue
);
1421 void blk_mq_start_stopped_hw_queues(struct request_queue
*q
, bool async
)
1423 struct blk_mq_hw_ctx
*hctx
;
1426 queue_for_each_hw_ctx(q
, hctx
, i
)
1427 blk_mq_start_stopped_hw_queue(hctx
, async
);
1429 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues
);
1431 static void blk_mq_run_work_fn(struct work_struct
*work
)
1433 struct blk_mq_hw_ctx
*hctx
;
1435 hctx
= container_of(work
, struct blk_mq_hw_ctx
, run_work
.work
);
1438 * If we are stopped, don't run the queue. The exception is if
1439 * BLK_MQ_S_START_ON_RUN is set. For that case, we auto-clear
1440 * the STOPPED bit and run it.
1442 if (test_bit(BLK_MQ_S_STOPPED
, &hctx
->state
)) {
1443 if (!test_bit(BLK_MQ_S_START_ON_RUN
, &hctx
->state
))
1446 clear_bit(BLK_MQ_S_START_ON_RUN
, &hctx
->state
);
1447 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1450 __blk_mq_run_hw_queue(hctx
);
1454 void blk_mq_delay_queue(struct blk_mq_hw_ctx
*hctx
, unsigned long msecs
)
1456 if (WARN_ON_ONCE(!blk_mq_hw_queue_mapped(hctx
)))
1460 * Stop the hw queue, then modify currently delayed work.
1461 * This should prevent us from running the queue prematurely.
1462 * Mark the queue as auto-clearing STOPPED when it runs.
1464 blk_mq_stop_hw_queue(hctx
);
1465 set_bit(BLK_MQ_S_START_ON_RUN
, &hctx
->state
);
1466 kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx
),
1468 msecs_to_jiffies(msecs
));
1470 EXPORT_SYMBOL(blk_mq_delay_queue
);
1472 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx
*hctx
,
1476 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1478 lockdep_assert_held(&ctx
->lock
);
1480 trace_block_rq_insert(hctx
->queue
, rq
);
1483 list_add(&rq
->queuelist
, &ctx
->rq_list
);
1485 list_add_tail(&rq
->queuelist
, &ctx
->rq_list
);
1488 void __blk_mq_insert_request(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
,
1491 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1493 lockdep_assert_held(&ctx
->lock
);
1495 __blk_mq_insert_req_list(hctx
, rq
, at_head
);
1496 blk_mq_hctx_mark_pending(hctx
, ctx
);
1500 * Should only be used carefully, when the caller knows we want to
1501 * bypass a potential IO scheduler on the target device.
1503 void blk_mq_request_bypass_insert(struct request
*rq
)
1505 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1506 struct blk_mq_hw_ctx
*hctx
= blk_mq_map_queue(rq
->q
, ctx
->cpu
);
1508 spin_lock(&hctx
->lock
);
1509 list_add_tail(&rq
->queuelist
, &hctx
->dispatch
);
1510 spin_unlock(&hctx
->lock
);
1512 blk_mq_run_hw_queue(hctx
, false);
1515 void blk_mq_insert_requests(struct blk_mq_hw_ctx
*hctx
, struct blk_mq_ctx
*ctx
,
1516 struct list_head
*list
)
1520 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1523 spin_lock(&ctx
->lock
);
1524 while (!list_empty(list
)) {
1527 rq
= list_first_entry(list
, struct request
, queuelist
);
1528 BUG_ON(rq
->mq_ctx
!= ctx
);
1529 list_del_init(&rq
->queuelist
);
1530 __blk_mq_insert_req_list(hctx
, rq
, false);
1532 blk_mq_hctx_mark_pending(hctx
, ctx
);
1533 spin_unlock(&ctx
->lock
);
1536 static int plug_ctx_cmp(void *priv
, struct list_head
*a
, struct list_head
*b
)
1538 struct request
*rqa
= container_of(a
, struct request
, queuelist
);
1539 struct request
*rqb
= container_of(b
, struct request
, queuelist
);
1541 return !(rqa
->mq_ctx
< rqb
->mq_ctx
||
1542 (rqa
->mq_ctx
== rqb
->mq_ctx
&&
1543 blk_rq_pos(rqa
) < blk_rq_pos(rqb
)));
1546 void blk_mq_flush_plug_list(struct blk_plug
*plug
, bool from_schedule
)
1548 struct blk_mq_ctx
*this_ctx
;
1549 struct request_queue
*this_q
;
1552 LIST_HEAD(ctx_list
);
1555 list_splice_init(&plug
->mq_list
, &list
);
1557 list_sort(NULL
, &list
, plug_ctx_cmp
);
1563 while (!list_empty(&list
)) {
1564 rq
= list_entry_rq(list
.next
);
1565 list_del_init(&rq
->queuelist
);
1567 if (rq
->mq_ctx
!= this_ctx
) {
1569 trace_block_unplug(this_q
, depth
, from_schedule
);
1570 blk_mq_sched_insert_requests(this_q
, this_ctx
,
1575 this_ctx
= rq
->mq_ctx
;
1581 list_add_tail(&rq
->queuelist
, &ctx_list
);
1585 * If 'this_ctx' is set, we know we have entries to complete
1586 * on 'ctx_list'. Do those.
1589 trace_block_unplug(this_q
, depth
, from_schedule
);
1590 blk_mq_sched_insert_requests(this_q
, this_ctx
, &ctx_list
,
1595 static void blk_mq_bio_to_request(struct request
*rq
, struct bio
*bio
)
1597 blk_init_request_from_bio(rq
, bio
);
1599 blk_rq_set_rl(rq
, blk_get_rl(rq
->q
, bio
));
1601 blk_account_io_start(rq
, true);
1604 static inline void blk_mq_queue_io(struct blk_mq_hw_ctx
*hctx
,
1605 struct blk_mq_ctx
*ctx
,
1608 spin_lock(&ctx
->lock
);
1609 __blk_mq_insert_request(hctx
, rq
, false);
1610 spin_unlock(&ctx
->lock
);
1613 static blk_qc_t
request_to_qc_t(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
)
1616 return blk_tag_to_qc_t(rq
->tag
, hctx
->queue_num
, false);
1618 return blk_tag_to_qc_t(rq
->internal_tag
, hctx
->queue_num
, true);
1621 static void __blk_mq_try_issue_directly(struct blk_mq_hw_ctx
*hctx
,
1623 blk_qc_t
*cookie
, bool may_sleep
)
1625 struct request_queue
*q
= rq
->q
;
1626 struct blk_mq_queue_data bd
= {
1630 blk_qc_t new_cookie
;
1632 bool run_queue
= true;
1634 /* RCU or SRCU read lock is needed before checking quiesced flag */
1635 if (blk_mq_hctx_stopped(hctx
) || blk_queue_quiesced(q
)) {
1643 if (!blk_mq_get_driver_tag(rq
, NULL
, false))
1646 ret
= blk_mq_get_dispatch_budget(hctx
);
1647 if (ret
== BLK_STS_RESOURCE
) {
1648 blk_mq_put_driver_tag(rq
);
1650 } else if (ret
!= BLK_STS_OK
)
1653 new_cookie
= request_to_qc_t(hctx
, rq
);
1656 * For OK queue, we are done. For error, kill it. Any other
1657 * error (busy), just add it to our list as we previously
1660 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1663 *cookie
= new_cookie
;
1665 case BLK_STS_RESOURCE
:
1666 __blk_mq_requeue_request(rq
);
1670 *cookie
= BLK_QC_T_NONE
;
1671 blk_mq_end_request(rq
, ret
);
1676 blk_mq_sched_insert_request(rq
, false, run_queue
, false, may_sleep
);
1679 static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx
*hctx
,
1680 struct request
*rq
, blk_qc_t
*cookie
)
1682 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1684 __blk_mq_try_issue_directly(hctx
, rq
, cookie
, false);
1687 unsigned int srcu_idx
;
1691 srcu_idx
= srcu_read_lock(hctx
->queue_rq_srcu
);
1692 __blk_mq_try_issue_directly(hctx
, rq
, cookie
, true);
1693 srcu_read_unlock(hctx
->queue_rq_srcu
, srcu_idx
);
1697 static blk_qc_t
blk_mq_make_request(struct request_queue
*q
, struct bio
*bio
)
1699 const int is_sync
= op_is_sync(bio
->bi_opf
);
1700 const int is_flush_fua
= op_is_flush(bio
->bi_opf
);
1701 struct blk_mq_alloc_data data
= { .flags
= 0 };
1703 unsigned int request_count
= 0;
1704 struct blk_plug
*plug
;
1705 struct request
*same_queue_rq
= NULL
;
1707 unsigned int wb_acct
;
1709 blk_queue_bounce(q
, &bio
);
1711 blk_queue_split(q
, &bio
);
1713 if (!bio_integrity_prep(bio
))
1714 return BLK_QC_T_NONE
;
1716 if (!is_flush_fua
&& !blk_queue_nomerges(q
) &&
1717 blk_attempt_plug_merge(q
, bio
, &request_count
, &same_queue_rq
))
1718 return BLK_QC_T_NONE
;
1720 if (blk_mq_sched_bio_merge(q
, bio
))
1721 return BLK_QC_T_NONE
;
1723 wb_acct
= wbt_wait(q
->rq_wb
, bio
, NULL
);
1725 trace_block_getrq(q
, bio
, bio
->bi_opf
);
1727 rq
= blk_mq_get_request(q
, bio
, bio
->bi_opf
, &data
);
1728 if (unlikely(!rq
)) {
1729 __wbt_done(q
->rq_wb
, wb_acct
);
1730 if (bio
->bi_opf
& REQ_NOWAIT
)
1731 bio_wouldblock_error(bio
);
1732 return BLK_QC_T_NONE
;
1735 wbt_track(&rq
->issue_stat
, wb_acct
);
1737 cookie
= request_to_qc_t(data
.hctx
, rq
);
1739 plug
= current
->plug
;
1740 if (unlikely(is_flush_fua
)) {
1741 blk_mq_put_ctx(data
.ctx
);
1742 blk_mq_bio_to_request(rq
, bio
);
1744 blk_mq_sched_insert_request(rq
, false, true, true,
1747 blk_insert_flush(rq
);
1748 blk_mq_run_hw_queue(data
.hctx
, true);
1750 } else if (plug
&& q
->nr_hw_queues
== 1) {
1751 struct request
*last
= NULL
;
1753 blk_mq_put_ctx(data
.ctx
);
1754 blk_mq_bio_to_request(rq
, bio
);
1757 * @request_count may become stale because of schedule
1758 * out, so check the list again.
1760 if (list_empty(&plug
->mq_list
))
1762 else if (blk_queue_nomerges(q
))
1763 request_count
= blk_plug_queued_count(q
);
1766 trace_block_plug(q
);
1768 last
= list_entry_rq(plug
->mq_list
.prev
);
1770 if (request_count
>= BLK_MAX_REQUEST_COUNT
|| (last
&&
1771 blk_rq_bytes(last
) >= BLK_PLUG_FLUSH_SIZE
)) {
1772 blk_flush_plug_list(plug
, false);
1773 trace_block_plug(q
);
1776 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1777 } else if (plug
&& !blk_queue_nomerges(q
)) {
1778 blk_mq_bio_to_request(rq
, bio
);
1781 * We do limited plugging. If the bio can be merged, do that.
1782 * Otherwise the existing request in the plug list will be
1783 * issued. So the plug list will have one request at most
1784 * The plug list might get flushed before this. If that happens,
1785 * the plug list is empty, and same_queue_rq is invalid.
1787 if (list_empty(&plug
->mq_list
))
1788 same_queue_rq
= NULL
;
1790 list_del_init(&same_queue_rq
->queuelist
);
1791 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1793 blk_mq_put_ctx(data
.ctx
);
1795 if (same_queue_rq
) {
1796 data
.hctx
= blk_mq_map_queue(q
,
1797 same_queue_rq
->mq_ctx
->cpu
);
1798 blk_mq_try_issue_directly(data
.hctx
, same_queue_rq
,
1801 } else if (q
->nr_hw_queues
> 1 && is_sync
) {
1802 blk_mq_put_ctx(data
.ctx
);
1803 blk_mq_bio_to_request(rq
, bio
);
1804 blk_mq_try_issue_directly(data
.hctx
, rq
, &cookie
);
1805 } else if (q
->elevator
) {
1806 blk_mq_put_ctx(data
.ctx
);
1807 blk_mq_bio_to_request(rq
, bio
);
1808 blk_mq_sched_insert_request(rq
, false, true, true, true);
1810 blk_mq_put_ctx(data
.ctx
);
1811 blk_mq_bio_to_request(rq
, bio
);
1812 blk_mq_queue_io(data
.hctx
, data
.ctx
, rq
);
1813 blk_mq_run_hw_queue(data
.hctx
, true);
1819 void blk_mq_free_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
1820 unsigned int hctx_idx
)
1824 if (tags
->rqs
&& set
->ops
->exit_request
) {
1827 for (i
= 0; i
< tags
->nr_tags
; i
++) {
1828 struct request
*rq
= tags
->static_rqs
[i
];
1832 set
->ops
->exit_request(set
, rq
, hctx_idx
);
1833 tags
->static_rqs
[i
] = NULL
;
1837 while (!list_empty(&tags
->page_list
)) {
1838 page
= list_first_entry(&tags
->page_list
, struct page
, lru
);
1839 list_del_init(&page
->lru
);
1841 * Remove kmemleak object previously allocated in
1842 * blk_mq_init_rq_map().
1844 kmemleak_free(page_address(page
));
1845 __free_pages(page
, page
->private);
1849 void blk_mq_free_rq_map(struct blk_mq_tags
*tags
)
1853 kfree(tags
->static_rqs
);
1854 tags
->static_rqs
= NULL
;
1856 blk_mq_free_tags(tags
);
1859 struct blk_mq_tags
*blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
,
1860 unsigned int hctx_idx
,
1861 unsigned int nr_tags
,
1862 unsigned int reserved_tags
)
1864 struct blk_mq_tags
*tags
;
1867 node
= blk_mq_hw_queue_to_node(set
->mq_map
, hctx_idx
);
1868 if (node
== NUMA_NO_NODE
)
1869 node
= set
->numa_node
;
1871 tags
= blk_mq_init_tags(nr_tags
, reserved_tags
, node
,
1872 BLK_MQ_FLAG_TO_ALLOC_POLICY(set
->flags
));
1876 tags
->rqs
= kzalloc_node(nr_tags
* sizeof(struct request
*),
1877 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
1880 blk_mq_free_tags(tags
);
1884 tags
->static_rqs
= kzalloc_node(nr_tags
* sizeof(struct request
*),
1885 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
1887 if (!tags
->static_rqs
) {
1889 blk_mq_free_tags(tags
);
1896 static size_t order_to_size(unsigned int order
)
1898 return (size_t)PAGE_SIZE
<< order
;
1901 int blk_mq_alloc_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
1902 unsigned int hctx_idx
, unsigned int depth
)
1904 unsigned int i
, j
, entries_per_page
, max_order
= 4;
1905 size_t rq_size
, left
;
1908 node
= blk_mq_hw_queue_to_node(set
->mq_map
, hctx_idx
);
1909 if (node
== NUMA_NO_NODE
)
1910 node
= set
->numa_node
;
1912 INIT_LIST_HEAD(&tags
->page_list
);
1915 * rq_size is the size of the request plus driver payload, rounded
1916 * to the cacheline size
1918 rq_size
= round_up(sizeof(struct request
) + set
->cmd_size
,
1920 left
= rq_size
* depth
;
1922 for (i
= 0; i
< depth
; ) {
1923 int this_order
= max_order
;
1928 while (this_order
&& left
< order_to_size(this_order
- 1))
1932 page
= alloc_pages_node(node
,
1933 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
| __GFP_ZERO
,
1939 if (order_to_size(this_order
) < rq_size
)
1946 page
->private = this_order
;
1947 list_add_tail(&page
->lru
, &tags
->page_list
);
1949 p
= page_address(page
);
1951 * Allow kmemleak to scan these pages as they contain pointers
1952 * to additional allocations like via ops->init_request().
1954 kmemleak_alloc(p
, order_to_size(this_order
), 1, GFP_NOIO
);
1955 entries_per_page
= order_to_size(this_order
) / rq_size
;
1956 to_do
= min(entries_per_page
, depth
- i
);
1957 left
-= to_do
* rq_size
;
1958 for (j
= 0; j
< to_do
; j
++) {
1959 struct request
*rq
= p
;
1961 tags
->static_rqs
[i
] = rq
;
1962 if (set
->ops
->init_request
) {
1963 if (set
->ops
->init_request(set
, rq
, hctx_idx
,
1965 tags
->static_rqs
[i
] = NULL
;
1977 blk_mq_free_rqs(set
, tags
, hctx_idx
);
1982 * 'cpu' is going away. splice any existing rq_list entries from this
1983 * software queue to the hw queue dispatch list, and ensure that it
1986 static int blk_mq_hctx_notify_dead(unsigned int cpu
, struct hlist_node
*node
)
1988 struct blk_mq_hw_ctx
*hctx
;
1989 struct blk_mq_ctx
*ctx
;
1992 hctx
= hlist_entry_safe(node
, struct blk_mq_hw_ctx
, cpuhp_dead
);
1993 ctx
= __blk_mq_get_ctx(hctx
->queue
, cpu
);
1995 spin_lock(&ctx
->lock
);
1996 if (!list_empty(&ctx
->rq_list
)) {
1997 list_splice_init(&ctx
->rq_list
, &tmp
);
1998 blk_mq_hctx_clear_pending(hctx
, ctx
);
2000 spin_unlock(&ctx
->lock
);
2002 if (list_empty(&tmp
))
2005 spin_lock(&hctx
->lock
);
2006 list_splice_tail_init(&tmp
, &hctx
->dispatch
);
2007 spin_unlock(&hctx
->lock
);
2009 blk_mq_run_hw_queue(hctx
, true);
2013 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx
*hctx
)
2015 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD
,
2019 /* hctx->ctxs will be freed in queue's release handler */
2020 static void blk_mq_exit_hctx(struct request_queue
*q
,
2021 struct blk_mq_tag_set
*set
,
2022 struct blk_mq_hw_ctx
*hctx
, unsigned int hctx_idx
)
2024 blk_mq_debugfs_unregister_hctx(hctx
);
2026 blk_mq_tag_idle(hctx
);
2028 if (set
->ops
->exit_request
)
2029 set
->ops
->exit_request(set
, hctx
->fq
->flush_rq
, hctx_idx
);
2031 blk_mq_sched_exit_hctx(q
, hctx
, hctx_idx
);
2033 if (set
->ops
->exit_hctx
)
2034 set
->ops
->exit_hctx(hctx
, hctx_idx
);
2036 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
2037 cleanup_srcu_struct(hctx
->queue_rq_srcu
);
2039 blk_mq_remove_cpuhp(hctx
);
2040 blk_free_flush_queue(hctx
->fq
);
2041 sbitmap_free(&hctx
->ctx_map
);
2044 static void blk_mq_exit_hw_queues(struct request_queue
*q
,
2045 struct blk_mq_tag_set
*set
, int nr_queue
)
2047 struct blk_mq_hw_ctx
*hctx
;
2050 queue_for_each_hw_ctx(q
, hctx
, i
) {
2053 blk_mq_exit_hctx(q
, set
, hctx
, i
);
2057 static int blk_mq_init_hctx(struct request_queue
*q
,
2058 struct blk_mq_tag_set
*set
,
2059 struct blk_mq_hw_ctx
*hctx
, unsigned hctx_idx
)
2063 node
= hctx
->numa_node
;
2064 if (node
== NUMA_NO_NODE
)
2065 node
= hctx
->numa_node
= set
->numa_node
;
2067 INIT_DELAYED_WORK(&hctx
->run_work
, blk_mq_run_work_fn
);
2068 spin_lock_init(&hctx
->lock
);
2069 INIT_LIST_HEAD(&hctx
->dispatch
);
2071 hctx
->flags
= set
->flags
& ~BLK_MQ_F_TAG_SHARED
;
2073 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD
, &hctx
->cpuhp_dead
);
2075 hctx
->tags
= set
->tags
[hctx_idx
];
2078 * Allocate space for all possible cpus to avoid allocation at
2081 hctx
->ctxs
= kmalloc_node(nr_cpu_ids
* sizeof(void *),
2084 goto unregister_cpu_notifier
;
2086 if (sbitmap_init_node(&hctx
->ctx_map
, nr_cpu_ids
, ilog2(8), GFP_KERNEL
,
2092 if (set
->ops
->init_hctx
&&
2093 set
->ops
->init_hctx(hctx
, set
->driver_data
, hctx_idx
))
2096 if (blk_mq_sched_init_hctx(q
, hctx
, hctx_idx
))
2099 hctx
->fq
= blk_alloc_flush_queue(q
, hctx
->numa_node
, set
->cmd_size
);
2101 goto sched_exit_hctx
;
2103 if (set
->ops
->init_request
&&
2104 set
->ops
->init_request(set
, hctx
->fq
->flush_rq
, hctx_idx
,
2108 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
2109 init_srcu_struct(hctx
->queue_rq_srcu
);
2111 blk_mq_debugfs_register_hctx(q
, hctx
);
2118 blk_mq_sched_exit_hctx(q
, hctx
, hctx_idx
);
2120 if (set
->ops
->exit_hctx
)
2121 set
->ops
->exit_hctx(hctx
, hctx_idx
);
2123 sbitmap_free(&hctx
->ctx_map
);
2126 unregister_cpu_notifier
:
2127 blk_mq_remove_cpuhp(hctx
);
2131 static void blk_mq_init_cpu_queues(struct request_queue
*q
,
2132 unsigned int nr_hw_queues
)
2136 for_each_possible_cpu(i
) {
2137 struct blk_mq_ctx
*__ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
2138 struct blk_mq_hw_ctx
*hctx
;
2141 spin_lock_init(&__ctx
->lock
);
2142 INIT_LIST_HEAD(&__ctx
->rq_list
);
2145 /* If the cpu isn't present, the cpu is mapped to first hctx */
2146 if (!cpu_present(i
))
2149 hctx
= blk_mq_map_queue(q
, i
);
2152 * Set local node, IFF we have more than one hw queue. If
2153 * not, we remain on the home node of the device
2155 if (nr_hw_queues
> 1 && hctx
->numa_node
== NUMA_NO_NODE
)
2156 hctx
->numa_node
= local_memory_node(cpu_to_node(i
));
2160 static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
, int hctx_idx
)
2164 set
->tags
[hctx_idx
] = blk_mq_alloc_rq_map(set
, hctx_idx
,
2165 set
->queue_depth
, set
->reserved_tags
);
2166 if (!set
->tags
[hctx_idx
])
2169 ret
= blk_mq_alloc_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
,
2174 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
2175 set
->tags
[hctx_idx
] = NULL
;
2179 static void blk_mq_free_map_and_requests(struct blk_mq_tag_set
*set
,
2180 unsigned int hctx_idx
)
2182 if (set
->tags
[hctx_idx
]) {
2183 blk_mq_free_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
);
2184 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
2185 set
->tags
[hctx_idx
] = NULL
;
2189 static void blk_mq_map_swqueue(struct request_queue
*q
)
2191 unsigned int i
, hctx_idx
;
2192 struct blk_mq_hw_ctx
*hctx
;
2193 struct blk_mq_ctx
*ctx
;
2194 struct blk_mq_tag_set
*set
= q
->tag_set
;
2197 * Avoid others reading imcomplete hctx->cpumask through sysfs
2199 mutex_lock(&q
->sysfs_lock
);
2201 queue_for_each_hw_ctx(q
, hctx
, i
) {
2202 cpumask_clear(hctx
->cpumask
);
2207 * Map software to hardware queues.
2209 * If the cpu isn't present, the cpu is mapped to first hctx.
2211 for_each_present_cpu(i
) {
2212 hctx_idx
= q
->mq_map
[i
];
2213 /* unmapped hw queue can be remapped after CPU topo changed */
2214 if (!set
->tags
[hctx_idx
] &&
2215 !__blk_mq_alloc_rq_map(set
, hctx_idx
)) {
2217 * If tags initialization fail for some hctx,
2218 * that hctx won't be brought online. In this
2219 * case, remap the current ctx to hctx[0] which
2220 * is guaranteed to always have tags allocated
2225 ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
2226 hctx
= blk_mq_map_queue(q
, i
);
2228 cpumask_set_cpu(i
, hctx
->cpumask
);
2229 ctx
->index_hw
= hctx
->nr_ctx
;
2230 hctx
->ctxs
[hctx
->nr_ctx
++] = ctx
;
2233 mutex_unlock(&q
->sysfs_lock
);
2235 queue_for_each_hw_ctx(q
, hctx
, i
) {
2237 * If no software queues are mapped to this hardware queue,
2238 * disable it and free the request entries.
2240 if (!hctx
->nr_ctx
) {
2241 /* Never unmap queue 0. We need it as a
2242 * fallback in case of a new remap fails
2245 if (i
&& set
->tags
[i
])
2246 blk_mq_free_map_and_requests(set
, i
);
2252 hctx
->tags
= set
->tags
[i
];
2253 WARN_ON(!hctx
->tags
);
2256 * Set the map size to the number of mapped software queues.
2257 * This is more accurate and more efficient than looping
2258 * over all possibly mapped software queues.
2260 sbitmap_resize(&hctx
->ctx_map
, hctx
->nr_ctx
);
2263 * Initialize batch roundrobin counts
2265 hctx
->next_cpu
= cpumask_first(hctx
->cpumask
);
2266 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
2271 * Caller needs to ensure that we're either frozen/quiesced, or that
2272 * the queue isn't live yet.
2274 static void queue_set_hctx_shared(struct request_queue
*q
, bool shared
)
2276 struct blk_mq_hw_ctx
*hctx
;
2279 queue_for_each_hw_ctx(q
, hctx
, i
) {
2281 if (test_bit(BLK_MQ_S_SCHED_RESTART
, &hctx
->state
))
2282 atomic_inc(&q
->shared_hctx_restart
);
2283 hctx
->flags
|= BLK_MQ_F_TAG_SHARED
;
2285 if (test_bit(BLK_MQ_S_SCHED_RESTART
, &hctx
->state
))
2286 atomic_dec(&q
->shared_hctx_restart
);
2287 hctx
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2292 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set
*set
,
2295 struct request_queue
*q
;
2297 lockdep_assert_held(&set
->tag_list_lock
);
2299 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
2300 blk_mq_freeze_queue(q
);
2301 queue_set_hctx_shared(q
, shared
);
2302 blk_mq_unfreeze_queue(q
);
2306 static void blk_mq_del_queue_tag_set(struct request_queue
*q
)
2308 struct blk_mq_tag_set
*set
= q
->tag_set
;
2310 mutex_lock(&set
->tag_list_lock
);
2311 list_del_rcu(&q
->tag_set_list
);
2312 INIT_LIST_HEAD(&q
->tag_set_list
);
2313 if (list_is_singular(&set
->tag_list
)) {
2314 /* just transitioned to unshared */
2315 set
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2316 /* update existing queue */
2317 blk_mq_update_tag_set_depth(set
, false);
2319 mutex_unlock(&set
->tag_list_lock
);
2324 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set
*set
,
2325 struct request_queue
*q
)
2329 mutex_lock(&set
->tag_list_lock
);
2331 /* Check to see if we're transitioning to shared (from 1 to 2 queues). */
2332 if (!list_empty(&set
->tag_list
) && !(set
->flags
& BLK_MQ_F_TAG_SHARED
)) {
2333 set
->flags
|= BLK_MQ_F_TAG_SHARED
;
2334 /* update existing queue */
2335 blk_mq_update_tag_set_depth(set
, true);
2337 if (set
->flags
& BLK_MQ_F_TAG_SHARED
)
2338 queue_set_hctx_shared(q
, true);
2339 list_add_tail_rcu(&q
->tag_set_list
, &set
->tag_list
);
2341 mutex_unlock(&set
->tag_list_lock
);
2345 * It is the actual release handler for mq, but we do it from
2346 * request queue's release handler for avoiding use-after-free
2347 * and headache because q->mq_kobj shouldn't have been introduced,
2348 * but we can't group ctx/kctx kobj without it.
2350 void blk_mq_release(struct request_queue
*q
)
2352 struct blk_mq_hw_ctx
*hctx
;
2355 /* hctx kobj stays in hctx */
2356 queue_for_each_hw_ctx(q
, hctx
, i
) {
2359 kobject_put(&hctx
->kobj
);
2364 kfree(q
->queue_hw_ctx
);
2367 * release .mq_kobj and sw queue's kobject now because
2368 * both share lifetime with request queue.
2370 blk_mq_sysfs_deinit(q
);
2372 free_percpu(q
->queue_ctx
);
2375 struct request_queue
*blk_mq_init_queue(struct blk_mq_tag_set
*set
)
2377 struct request_queue
*uninit_q
, *q
;
2379 uninit_q
= blk_alloc_queue_node(GFP_KERNEL
, set
->numa_node
);
2381 return ERR_PTR(-ENOMEM
);
2383 q
= blk_mq_init_allocated_queue(set
, uninit_q
);
2385 blk_cleanup_queue(uninit_q
);
2389 EXPORT_SYMBOL(blk_mq_init_queue
);
2391 static int blk_mq_hw_ctx_size(struct blk_mq_tag_set
*tag_set
)
2393 int hw_ctx_size
= sizeof(struct blk_mq_hw_ctx
);
2395 BUILD_BUG_ON(ALIGN(offsetof(struct blk_mq_hw_ctx
, queue_rq_srcu
),
2396 __alignof__(struct blk_mq_hw_ctx
)) !=
2397 sizeof(struct blk_mq_hw_ctx
));
2399 if (tag_set
->flags
& BLK_MQ_F_BLOCKING
)
2400 hw_ctx_size
+= sizeof(struct srcu_struct
);
2405 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set
*set
,
2406 struct request_queue
*q
)
2409 struct blk_mq_hw_ctx
**hctxs
= q
->queue_hw_ctx
;
2411 blk_mq_sysfs_unregister(q
);
2412 for (i
= 0; i
< set
->nr_hw_queues
; i
++) {
2418 node
= blk_mq_hw_queue_to_node(q
->mq_map
, i
);
2419 hctxs
[i
] = kzalloc_node(blk_mq_hw_ctx_size(set
),
2424 if (!zalloc_cpumask_var_node(&hctxs
[i
]->cpumask
, GFP_KERNEL
,
2431 atomic_set(&hctxs
[i
]->nr_active
, 0);
2432 hctxs
[i
]->numa_node
= node
;
2433 hctxs
[i
]->queue_num
= i
;
2435 if (blk_mq_init_hctx(q
, set
, hctxs
[i
], i
)) {
2436 free_cpumask_var(hctxs
[i
]->cpumask
);
2441 blk_mq_hctx_kobj_init(hctxs
[i
]);
2443 for (j
= i
; j
< q
->nr_hw_queues
; j
++) {
2444 struct blk_mq_hw_ctx
*hctx
= hctxs
[j
];
2448 blk_mq_free_map_and_requests(set
, j
);
2449 blk_mq_exit_hctx(q
, set
, hctx
, j
);
2450 kobject_put(&hctx
->kobj
);
2455 q
->nr_hw_queues
= i
;
2456 blk_mq_sysfs_register(q
);
2459 struct request_queue
*blk_mq_init_allocated_queue(struct blk_mq_tag_set
*set
,
2460 struct request_queue
*q
)
2462 /* mark the queue as mq asap */
2463 q
->mq_ops
= set
->ops
;
2465 q
->poll_cb
= blk_stat_alloc_callback(blk_mq_poll_stats_fn
,
2466 blk_mq_poll_stats_bkt
,
2467 BLK_MQ_POLL_STATS_BKTS
, q
);
2471 q
->queue_ctx
= alloc_percpu(struct blk_mq_ctx
);
2475 /* init q->mq_kobj and sw queues' kobjects */
2476 blk_mq_sysfs_init(q
);
2478 q
->queue_hw_ctx
= kzalloc_node(nr_cpu_ids
* sizeof(*(q
->queue_hw_ctx
)),
2479 GFP_KERNEL
, set
->numa_node
);
2480 if (!q
->queue_hw_ctx
)
2483 q
->mq_map
= set
->mq_map
;
2485 blk_mq_realloc_hw_ctxs(set
, q
);
2486 if (!q
->nr_hw_queues
)
2489 INIT_WORK(&q
->timeout_work
, blk_mq_timeout_work
);
2490 blk_queue_rq_timeout(q
, set
->timeout
? set
->timeout
: 30 * HZ
);
2492 q
->nr_queues
= nr_cpu_ids
;
2494 q
->queue_flags
|= QUEUE_FLAG_MQ_DEFAULT
;
2496 if (!(set
->flags
& BLK_MQ_F_SG_MERGE
))
2497 q
->queue_flags
|= 1 << QUEUE_FLAG_NO_SG_MERGE
;
2499 q
->sg_reserved_size
= INT_MAX
;
2501 INIT_DELAYED_WORK(&q
->requeue_work
, blk_mq_requeue_work
);
2502 INIT_LIST_HEAD(&q
->requeue_list
);
2503 spin_lock_init(&q
->requeue_lock
);
2505 blk_queue_make_request(q
, blk_mq_make_request
);
2508 * Do this after blk_queue_make_request() overrides it...
2510 q
->nr_requests
= set
->queue_depth
;
2513 * Default to classic polling
2517 if (set
->ops
->complete
)
2518 blk_queue_softirq_done(q
, set
->ops
->complete
);
2520 blk_mq_init_cpu_queues(q
, set
->nr_hw_queues
);
2521 blk_mq_add_queue_tag_set(set
, q
);
2522 blk_mq_map_swqueue(q
);
2524 if (!(set
->flags
& BLK_MQ_F_NO_SCHED
)) {
2527 ret
= blk_mq_sched_init(q
);
2529 return ERR_PTR(ret
);
2535 kfree(q
->queue_hw_ctx
);
2537 free_percpu(q
->queue_ctx
);
2540 return ERR_PTR(-ENOMEM
);
2542 EXPORT_SYMBOL(blk_mq_init_allocated_queue
);
2544 void blk_mq_free_queue(struct request_queue
*q
)
2546 struct blk_mq_tag_set
*set
= q
->tag_set
;
2548 blk_mq_del_queue_tag_set(q
);
2549 blk_mq_exit_hw_queues(q
, set
, set
->nr_hw_queues
);
2552 /* Basically redo blk_mq_init_queue with queue frozen */
2553 static void blk_mq_queue_reinit(struct request_queue
*q
)
2555 WARN_ON_ONCE(!atomic_read(&q
->mq_freeze_depth
));
2557 blk_mq_debugfs_unregister_hctxs(q
);
2558 blk_mq_sysfs_unregister(q
);
2561 * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
2562 * we should change hctx numa_node according to new topology (this
2563 * involves free and re-allocate memory, worthy doing?)
2566 blk_mq_map_swqueue(q
);
2568 blk_mq_sysfs_register(q
);
2569 blk_mq_debugfs_register_hctxs(q
);
2572 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2576 for (i
= 0; i
< set
->nr_hw_queues
; i
++)
2577 if (!__blk_mq_alloc_rq_map(set
, i
))
2584 blk_mq_free_rq_map(set
->tags
[i
]);
2590 * Allocate the request maps associated with this tag_set. Note that this
2591 * may reduce the depth asked for, if memory is tight. set->queue_depth
2592 * will be updated to reflect the allocated depth.
2594 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2599 depth
= set
->queue_depth
;
2601 err
= __blk_mq_alloc_rq_maps(set
);
2605 set
->queue_depth
>>= 1;
2606 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
) {
2610 } while (set
->queue_depth
);
2612 if (!set
->queue_depth
|| err
) {
2613 pr_err("blk-mq: failed to allocate request map\n");
2617 if (depth
!= set
->queue_depth
)
2618 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2619 depth
, set
->queue_depth
);
2624 static int blk_mq_update_queue_map(struct blk_mq_tag_set
*set
)
2626 if (set
->ops
->map_queues
)
2627 return set
->ops
->map_queues(set
);
2629 return blk_mq_map_queues(set
);
2633 * Alloc a tag set to be associated with one or more request queues.
2634 * May fail with EINVAL for various error conditions. May adjust the
2635 * requested depth down, if if it too large. In that case, the set
2636 * value will be stored in set->queue_depth.
2638 int blk_mq_alloc_tag_set(struct blk_mq_tag_set
*set
)
2642 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH
> 1 << BLK_MQ_UNIQUE_TAG_BITS
);
2644 if (!set
->nr_hw_queues
)
2646 if (!set
->queue_depth
)
2648 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
)
2651 if (!set
->ops
->queue_rq
)
2654 if (!set
->ops
->get_budget
^ !set
->ops
->put_budget
)
2657 if (set
->queue_depth
> BLK_MQ_MAX_DEPTH
) {
2658 pr_info("blk-mq: reduced tag depth to %u\n",
2660 set
->queue_depth
= BLK_MQ_MAX_DEPTH
;
2664 * If a crashdump is active, then we are potentially in a very
2665 * memory constrained environment. Limit us to 1 queue and
2666 * 64 tags to prevent using too much memory.
2668 if (is_kdump_kernel()) {
2669 set
->nr_hw_queues
= 1;
2670 set
->queue_depth
= min(64U, set
->queue_depth
);
2673 * There is no use for more h/w queues than cpus.
2675 if (set
->nr_hw_queues
> nr_cpu_ids
)
2676 set
->nr_hw_queues
= nr_cpu_ids
;
2678 set
->tags
= kzalloc_node(nr_cpu_ids
* sizeof(struct blk_mq_tags
*),
2679 GFP_KERNEL
, set
->numa_node
);
2684 set
->mq_map
= kzalloc_node(sizeof(*set
->mq_map
) * nr_cpu_ids
,
2685 GFP_KERNEL
, set
->numa_node
);
2689 ret
= blk_mq_update_queue_map(set
);
2691 goto out_free_mq_map
;
2693 ret
= blk_mq_alloc_rq_maps(set
);
2695 goto out_free_mq_map
;
2697 mutex_init(&set
->tag_list_lock
);
2698 INIT_LIST_HEAD(&set
->tag_list
);
2710 EXPORT_SYMBOL(blk_mq_alloc_tag_set
);
2712 void blk_mq_free_tag_set(struct blk_mq_tag_set
*set
)
2716 for (i
= 0; i
< nr_cpu_ids
; i
++)
2717 blk_mq_free_map_and_requests(set
, i
);
2725 EXPORT_SYMBOL(blk_mq_free_tag_set
);
2727 int blk_mq_update_nr_requests(struct request_queue
*q
, unsigned int nr
)
2729 struct blk_mq_tag_set
*set
= q
->tag_set
;
2730 struct blk_mq_hw_ctx
*hctx
;
2736 blk_mq_freeze_queue(q
);
2739 queue_for_each_hw_ctx(q
, hctx
, i
) {
2743 * If we're using an MQ scheduler, just update the scheduler
2744 * queue depth. This is similar to what the old code would do.
2746 if (!hctx
->sched_tags
) {
2747 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->tags
,
2748 min(nr
, set
->queue_depth
),
2751 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->sched_tags
,
2759 q
->nr_requests
= nr
;
2761 blk_mq_unfreeze_queue(q
);
2766 static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
,
2769 struct request_queue
*q
;
2771 lockdep_assert_held(&set
->tag_list_lock
);
2773 if (nr_hw_queues
> nr_cpu_ids
)
2774 nr_hw_queues
= nr_cpu_ids
;
2775 if (nr_hw_queues
< 1 || nr_hw_queues
== set
->nr_hw_queues
)
2778 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
2779 blk_mq_freeze_queue(q
);
2781 set
->nr_hw_queues
= nr_hw_queues
;
2782 blk_mq_update_queue_map(set
);
2783 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
2784 blk_mq_realloc_hw_ctxs(set
, q
);
2785 blk_mq_queue_reinit(q
);
2788 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
2789 blk_mq_unfreeze_queue(q
);
2792 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
, int nr_hw_queues
)
2794 mutex_lock(&set
->tag_list_lock
);
2795 __blk_mq_update_nr_hw_queues(set
, nr_hw_queues
);
2796 mutex_unlock(&set
->tag_list_lock
);
2798 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues
);
2800 /* Enable polling stats and return whether they were already enabled. */
2801 static bool blk_poll_stats_enable(struct request_queue
*q
)
2803 if (test_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
) ||
2804 test_and_set_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
))
2806 blk_stat_add_callback(q
, q
->poll_cb
);
2810 static void blk_mq_poll_stats_start(struct request_queue
*q
)
2813 * We don't arm the callback if polling stats are not enabled or the
2814 * callback is already active.
2816 if (!test_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
) ||
2817 blk_stat_is_active(q
->poll_cb
))
2820 blk_stat_activate_msecs(q
->poll_cb
, 100);
2823 static void blk_mq_poll_stats_fn(struct blk_stat_callback
*cb
)
2825 struct request_queue
*q
= cb
->data
;
2828 for (bucket
= 0; bucket
< BLK_MQ_POLL_STATS_BKTS
; bucket
++) {
2829 if (cb
->stat
[bucket
].nr_samples
)
2830 q
->poll_stat
[bucket
] = cb
->stat
[bucket
];
2834 static unsigned long blk_mq_poll_nsecs(struct request_queue
*q
,
2835 struct blk_mq_hw_ctx
*hctx
,
2838 unsigned long ret
= 0;
2842 * If stats collection isn't on, don't sleep but turn it on for
2845 if (!blk_poll_stats_enable(q
))
2849 * As an optimistic guess, use half of the mean service time
2850 * for this type of request. We can (and should) make this smarter.
2851 * For instance, if the completion latencies are tight, we can
2852 * get closer than just half the mean. This is especially
2853 * important on devices where the completion latencies are longer
2854 * than ~10 usec. We do use the stats for the relevant IO size
2855 * if available which does lead to better estimates.
2857 bucket
= blk_mq_poll_stats_bkt(rq
);
2861 if (q
->poll_stat
[bucket
].nr_samples
)
2862 ret
= (q
->poll_stat
[bucket
].mean
+ 1) / 2;
2867 static bool blk_mq_poll_hybrid_sleep(struct request_queue
*q
,
2868 struct blk_mq_hw_ctx
*hctx
,
2871 struct hrtimer_sleeper hs
;
2872 enum hrtimer_mode mode
;
2876 if (test_bit(REQ_ATOM_POLL_SLEPT
, &rq
->atomic_flags
))
2882 * -1: don't ever hybrid sleep
2883 * 0: use half of prev avg
2884 * >0: use this specific value
2886 if (q
->poll_nsec
== -1)
2888 else if (q
->poll_nsec
> 0)
2889 nsecs
= q
->poll_nsec
;
2891 nsecs
= blk_mq_poll_nsecs(q
, hctx
, rq
);
2896 set_bit(REQ_ATOM_POLL_SLEPT
, &rq
->atomic_flags
);
2899 * This will be replaced with the stats tracking code, using
2900 * 'avg_completion_time / 2' as the pre-sleep target.
2904 mode
= HRTIMER_MODE_REL
;
2905 hrtimer_init_on_stack(&hs
.timer
, CLOCK_MONOTONIC
, mode
);
2906 hrtimer_set_expires(&hs
.timer
, kt
);
2908 hrtimer_init_sleeper(&hs
, current
);
2910 if (test_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
))
2912 set_current_state(TASK_UNINTERRUPTIBLE
);
2913 hrtimer_start_expires(&hs
.timer
, mode
);
2916 hrtimer_cancel(&hs
.timer
);
2917 mode
= HRTIMER_MODE_ABS
;
2918 } while (hs
.task
&& !signal_pending(current
));
2920 __set_current_state(TASK_RUNNING
);
2921 destroy_hrtimer_on_stack(&hs
.timer
);
2925 static bool __blk_mq_poll(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
)
2927 struct request_queue
*q
= hctx
->queue
;
2931 * If we sleep, have the caller restart the poll loop to reset
2932 * the state. Like for the other success return cases, the
2933 * caller is responsible for checking if the IO completed. If
2934 * the IO isn't complete, we'll get called again and will go
2935 * straight to the busy poll loop.
2937 if (blk_mq_poll_hybrid_sleep(q
, hctx
, rq
))
2940 hctx
->poll_considered
++;
2942 state
= current
->state
;
2943 while (!need_resched()) {
2946 hctx
->poll_invoked
++;
2948 ret
= q
->mq_ops
->poll(hctx
, rq
->tag
);
2950 hctx
->poll_success
++;
2951 set_current_state(TASK_RUNNING
);
2955 if (signal_pending_state(state
, current
))
2956 set_current_state(TASK_RUNNING
);
2958 if (current
->state
== TASK_RUNNING
)
2968 bool blk_mq_poll(struct request_queue
*q
, blk_qc_t cookie
)
2970 struct blk_mq_hw_ctx
*hctx
;
2971 struct blk_plug
*plug
;
2974 if (!q
->mq_ops
|| !q
->mq_ops
->poll
|| !blk_qc_t_valid(cookie
) ||
2975 !test_bit(QUEUE_FLAG_POLL
, &q
->queue_flags
))
2978 plug
= current
->plug
;
2980 blk_flush_plug_list(plug
, false);
2982 hctx
= q
->queue_hw_ctx
[blk_qc_t_to_queue_num(cookie
)];
2983 if (!blk_qc_t_is_internal(cookie
))
2984 rq
= blk_mq_tag_to_rq(hctx
->tags
, blk_qc_t_to_tag(cookie
));
2986 rq
= blk_mq_tag_to_rq(hctx
->sched_tags
, blk_qc_t_to_tag(cookie
));
2988 * With scheduling, if the request has completed, we'll
2989 * get a NULL return here, as we clear the sched tag when
2990 * that happens. The request still remains valid, like always,
2991 * so we should be safe with just the NULL check.
2997 return __blk_mq_poll(hctx
, rq
);
2999 EXPORT_SYMBOL_GPL(blk_mq_poll
);
3001 static int __init
blk_mq_init(void)
3004 * See comment in block/blk.h rq_atomic_flags enum
3006 BUILD_BUG_ON((REQ_ATOM_STARTED
/ BITS_PER_BYTE
) !=
3007 (REQ_ATOM_COMPLETE
/ BITS_PER_BYTE
));
3009 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD
, "block/mq:dead", NULL
,
3010 blk_mq_hctx_notify_dead
);
3013 subsys_initcall(blk_mq_init
);