1 // SPDX-License-Identifier: GPL-2.0
3 * Block multiqueue core code
5 * Copyright (C) 2013-2014 Jens Axboe
6 * Copyright (C) 2013-2014 Christoph Hellwig
8 #include <linux/kernel.h>
9 #include <linux/module.h>
10 #include <linux/backing-dev.h>
11 #include <linux/bio.h>
12 #include <linux/blkdev.h>
13 #include <linux/kmemleak.h>
15 #include <linux/init.h>
16 #include <linux/slab.h>
17 #include <linux/workqueue.h>
18 #include <linux/smp.h>
19 #include <linux/llist.h>
20 #include <linux/list_sort.h>
21 #include <linux/cpu.h>
22 #include <linux/cache.h>
23 #include <linux/sched/sysctl.h>
24 #include <linux/sched/topology.h>
25 #include <linux/sched/signal.h>
26 #include <linux/delay.h>
27 #include <linux/crash_dump.h>
28 #include <linux/prefetch.h>
29 #include <linux/blk-crypto.h>
31 #include <trace/events/block.h>
33 #include <linux/blk-mq.h>
34 #include <linux/t10-pi.h>
37 #include "blk-mq-debugfs.h"
38 #include "blk-mq-tag.h"
41 #include "blk-mq-sched.h"
42 #include "blk-rq-qos.h"
44 static DEFINE_PER_CPU(struct llist_head
, blk_cpu_done
);
46 static void blk_mq_poll_stats_start(struct request_queue
*q
);
47 static void blk_mq_poll_stats_fn(struct blk_stat_callback
*cb
);
49 static int blk_mq_poll_stats_bkt(const struct request
*rq
)
51 int ddir
, sectors
, bucket
;
53 ddir
= rq_data_dir(rq
);
54 sectors
= blk_rq_stats_sectors(rq
);
56 bucket
= ddir
+ 2 * ilog2(sectors
);
60 else if (bucket
>= BLK_MQ_POLL_STATS_BKTS
)
61 return ddir
+ BLK_MQ_POLL_STATS_BKTS
- 2;
67 * Check if any of the ctx, dispatch list or elevator
68 * have pending work in this hardware queue.
70 static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx
*hctx
)
72 return !list_empty_careful(&hctx
->dispatch
) ||
73 sbitmap_any_bit_set(&hctx
->ctx_map
) ||
74 blk_mq_sched_has_work(hctx
);
78 * Mark this ctx as having pending work in this hardware queue
80 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx
*hctx
,
81 struct blk_mq_ctx
*ctx
)
83 const int bit
= ctx
->index_hw
[hctx
->type
];
85 if (!sbitmap_test_bit(&hctx
->ctx_map
, bit
))
86 sbitmap_set_bit(&hctx
->ctx_map
, bit
);
89 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx
*hctx
,
90 struct blk_mq_ctx
*ctx
)
92 const int bit
= ctx
->index_hw
[hctx
->type
];
94 sbitmap_clear_bit(&hctx
->ctx_map
, bit
);
98 struct block_device
*part
;
99 unsigned int inflight
[2];
102 static bool blk_mq_check_inflight(struct blk_mq_hw_ctx
*hctx
,
103 struct request
*rq
, void *priv
,
106 struct mq_inflight
*mi
= priv
;
108 if ((!mi
->part
->bd_partno
|| rq
->part
== mi
->part
) &&
109 blk_mq_rq_state(rq
) == MQ_RQ_IN_FLIGHT
)
110 mi
->inflight
[rq_data_dir(rq
)]++;
115 unsigned int blk_mq_in_flight(struct request_queue
*q
,
116 struct block_device
*part
)
118 struct mq_inflight mi
= { .part
= part
};
120 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_inflight
, &mi
);
122 return mi
.inflight
[0] + mi
.inflight
[1];
125 void blk_mq_in_flight_rw(struct request_queue
*q
, struct block_device
*part
,
126 unsigned int inflight
[2])
128 struct mq_inflight mi
= { .part
= part
};
130 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_inflight
, &mi
);
131 inflight
[0] = mi
.inflight
[0];
132 inflight
[1] = mi
.inflight
[1];
135 void blk_freeze_queue_start(struct request_queue
*q
)
137 mutex_lock(&q
->mq_freeze_lock
);
138 if (++q
->mq_freeze_depth
== 1) {
139 percpu_ref_kill(&q
->q_usage_counter
);
140 mutex_unlock(&q
->mq_freeze_lock
);
142 blk_mq_run_hw_queues(q
, false);
144 mutex_unlock(&q
->mq_freeze_lock
);
147 EXPORT_SYMBOL_GPL(blk_freeze_queue_start
);
149 void blk_mq_freeze_queue_wait(struct request_queue
*q
)
151 wait_event(q
->mq_freeze_wq
, percpu_ref_is_zero(&q
->q_usage_counter
));
153 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait
);
155 int blk_mq_freeze_queue_wait_timeout(struct request_queue
*q
,
156 unsigned long timeout
)
158 return wait_event_timeout(q
->mq_freeze_wq
,
159 percpu_ref_is_zero(&q
->q_usage_counter
),
162 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout
);
165 * Guarantee no request is in use, so we can change any data structure of
166 * the queue afterward.
168 void blk_freeze_queue(struct request_queue
*q
)
171 * In the !blk_mq case we are only calling this to kill the
172 * q_usage_counter, otherwise this increases the freeze depth
173 * and waits for it to return to zero. For this reason there is
174 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
175 * exported to drivers as the only user for unfreeze is blk_mq.
177 blk_freeze_queue_start(q
);
178 blk_mq_freeze_queue_wait(q
);
181 void blk_mq_freeze_queue(struct request_queue
*q
)
184 * ...just an alias to keep freeze and unfreeze actions balanced
185 * in the blk_mq_* namespace
189 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue
);
191 void blk_mq_unfreeze_queue(struct request_queue
*q
)
193 mutex_lock(&q
->mq_freeze_lock
);
194 q
->mq_freeze_depth
--;
195 WARN_ON_ONCE(q
->mq_freeze_depth
< 0);
196 if (!q
->mq_freeze_depth
) {
197 percpu_ref_resurrect(&q
->q_usage_counter
);
198 wake_up_all(&q
->mq_freeze_wq
);
200 mutex_unlock(&q
->mq_freeze_lock
);
202 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue
);
205 * FIXME: replace the scsi_internal_device_*block_nowait() calls in the
206 * mpt3sas driver such that this function can be removed.
208 void blk_mq_quiesce_queue_nowait(struct request_queue
*q
)
210 blk_queue_flag_set(QUEUE_FLAG_QUIESCED
, q
);
212 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait
);
215 * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished
218 * Note: this function does not prevent that the struct request end_io()
219 * callback function is invoked. Once this function is returned, we make
220 * sure no dispatch can happen until the queue is unquiesced via
221 * blk_mq_unquiesce_queue().
223 void blk_mq_quiesce_queue(struct request_queue
*q
)
225 struct blk_mq_hw_ctx
*hctx
;
229 blk_mq_quiesce_queue_nowait(q
);
231 queue_for_each_hw_ctx(q
, hctx
, i
) {
232 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
233 synchronize_srcu(hctx
->srcu
);
240 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue
);
243 * blk_mq_unquiesce_queue() - counterpart of blk_mq_quiesce_queue()
246 * This function recovers queue into the state before quiescing
247 * which is done by blk_mq_quiesce_queue.
249 void blk_mq_unquiesce_queue(struct request_queue
*q
)
251 blk_queue_flag_clear(QUEUE_FLAG_QUIESCED
, q
);
253 /* dispatch requests which are inserted during quiescing */
254 blk_mq_run_hw_queues(q
, true);
256 EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue
);
258 void blk_mq_wake_waiters(struct request_queue
*q
)
260 struct blk_mq_hw_ctx
*hctx
;
263 queue_for_each_hw_ctx(q
, hctx
, i
)
264 if (blk_mq_hw_queue_mapped(hctx
))
265 blk_mq_tag_wakeup_all(hctx
->tags
, true);
269 * Only need start/end time stamping if we have iostat or
270 * blk stats enabled, or using an IO scheduler.
272 static inline bool blk_mq_need_time_stamp(struct request
*rq
)
274 return (rq
->rq_flags
& (RQF_IO_STAT
| RQF_STATS
)) || rq
->q
->elevator
;
277 static struct request
*blk_mq_rq_ctx_init(struct blk_mq_alloc_data
*data
,
278 unsigned int tag
, u64 alloc_time_ns
)
280 struct blk_mq_tags
*tags
= blk_mq_tags_from_data(data
);
281 struct request
*rq
= tags
->static_rqs
[tag
];
283 if (data
->q
->elevator
) {
284 rq
->tag
= BLK_MQ_NO_TAG
;
285 rq
->internal_tag
= tag
;
288 rq
->internal_tag
= BLK_MQ_NO_TAG
;
291 /* csd/requeue_work/fifo_time is initialized before use */
293 rq
->mq_ctx
= data
->ctx
;
294 rq
->mq_hctx
= data
->hctx
;
296 rq
->cmd_flags
= data
->cmd_flags
;
297 if (data
->flags
& BLK_MQ_REQ_PM
)
298 rq
->rq_flags
|= RQF_PM
;
299 if (blk_queue_io_stat(data
->q
))
300 rq
->rq_flags
|= RQF_IO_STAT
;
301 INIT_LIST_HEAD(&rq
->queuelist
);
302 INIT_HLIST_NODE(&rq
->hash
);
303 RB_CLEAR_NODE(&rq
->rb_node
);
306 #ifdef CONFIG_BLK_RQ_ALLOC_TIME
307 rq
->alloc_time_ns
= alloc_time_ns
;
309 if (blk_mq_need_time_stamp(rq
))
310 rq
->start_time_ns
= ktime_get_ns();
312 rq
->start_time_ns
= 0;
313 rq
->io_start_time_ns
= 0;
314 rq
->stats_sectors
= 0;
315 rq
->nr_phys_segments
= 0;
316 #if defined(CONFIG_BLK_DEV_INTEGRITY)
317 rq
->nr_integrity_segments
= 0;
319 blk_crypto_rq_set_defaults(rq
);
320 /* tag was already set */
321 WRITE_ONCE(rq
->deadline
, 0);
326 rq
->end_io_data
= NULL
;
328 data
->ctx
->rq_dispatched
[op_is_sync(data
->cmd_flags
)]++;
329 refcount_set(&rq
->ref
, 1);
331 if (!op_is_flush(data
->cmd_flags
)) {
332 struct elevator_queue
*e
= data
->q
->elevator
;
335 if (e
&& e
->type
->ops
.prepare_request
) {
336 if (e
->type
->icq_cache
)
337 blk_mq_sched_assign_ioc(rq
);
339 e
->type
->ops
.prepare_request(rq
);
340 rq
->rq_flags
|= RQF_ELVPRIV
;
344 data
->hctx
->queued
++;
348 static struct request
*__blk_mq_alloc_request(struct blk_mq_alloc_data
*data
)
350 struct request_queue
*q
= data
->q
;
351 struct elevator_queue
*e
= q
->elevator
;
352 u64 alloc_time_ns
= 0;
355 /* alloc_time includes depth and tag waits */
356 if (blk_queue_rq_alloc_time(q
))
357 alloc_time_ns
= ktime_get_ns();
359 if (data
->cmd_flags
& REQ_NOWAIT
)
360 data
->flags
|= BLK_MQ_REQ_NOWAIT
;
364 * Flush/passthrough requests are special and go directly to the
365 * dispatch list. Don't include reserved tags in the
366 * limiting, as it isn't useful.
368 if (!op_is_flush(data
->cmd_flags
) &&
369 !blk_op_is_passthrough(data
->cmd_flags
) &&
370 e
->type
->ops
.limit_depth
&&
371 !(data
->flags
& BLK_MQ_REQ_RESERVED
))
372 e
->type
->ops
.limit_depth(data
->cmd_flags
, data
);
376 data
->ctx
= blk_mq_get_ctx(q
);
377 data
->hctx
= blk_mq_map_queue(q
, data
->cmd_flags
, data
->ctx
);
379 blk_mq_tag_busy(data
->hctx
);
382 * Waiting allocations only fail because of an inactive hctx. In that
383 * case just retry the hctx assignment and tag allocation as CPU hotplug
384 * should have migrated us to an online CPU by now.
386 tag
= blk_mq_get_tag(data
);
387 if (tag
== BLK_MQ_NO_TAG
) {
388 if (data
->flags
& BLK_MQ_REQ_NOWAIT
)
392 * Give up the CPU and sleep for a random short time to ensure
393 * that thread using a realtime scheduling class are migrated
394 * off the CPU, and thus off the hctx that is going away.
399 return blk_mq_rq_ctx_init(data
, tag
, alloc_time_ns
);
402 struct request
*blk_mq_alloc_request(struct request_queue
*q
, unsigned int op
,
403 blk_mq_req_flags_t flags
)
405 struct blk_mq_alloc_data data
= {
413 ret
= blk_queue_enter(q
, flags
);
417 rq
= __blk_mq_alloc_request(&data
);
421 rq
->__sector
= (sector_t
) -1;
422 rq
->bio
= rq
->biotail
= NULL
;
426 return ERR_PTR(-EWOULDBLOCK
);
428 EXPORT_SYMBOL(blk_mq_alloc_request
);
430 struct request
*blk_mq_alloc_request_hctx(struct request_queue
*q
,
431 unsigned int op
, blk_mq_req_flags_t flags
, unsigned int hctx_idx
)
433 struct blk_mq_alloc_data data
= {
438 u64 alloc_time_ns
= 0;
443 /* alloc_time includes depth and tag waits */
444 if (blk_queue_rq_alloc_time(q
))
445 alloc_time_ns
= ktime_get_ns();
448 * If the tag allocator sleeps we could get an allocation for a
449 * different hardware context. No need to complicate the low level
450 * allocator for this for the rare use case of a command tied to
453 if (WARN_ON_ONCE(!(flags
& (BLK_MQ_REQ_NOWAIT
| BLK_MQ_REQ_RESERVED
))))
454 return ERR_PTR(-EINVAL
);
456 if (hctx_idx
>= q
->nr_hw_queues
)
457 return ERR_PTR(-EIO
);
459 ret
= blk_queue_enter(q
, flags
);
464 * Check if the hardware context is actually mapped to anything.
465 * If not tell the caller that it should skip this queue.
468 data
.hctx
= q
->queue_hw_ctx
[hctx_idx
];
469 if (!blk_mq_hw_queue_mapped(data
.hctx
))
471 cpu
= cpumask_first_and(data
.hctx
->cpumask
, cpu_online_mask
);
472 data
.ctx
= __blk_mq_get_ctx(q
, cpu
);
475 blk_mq_tag_busy(data
.hctx
);
478 tag
= blk_mq_get_tag(&data
);
479 if (tag
== BLK_MQ_NO_TAG
)
481 return blk_mq_rq_ctx_init(&data
, tag
, alloc_time_ns
);
487 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx
);
489 static void __blk_mq_free_request(struct request
*rq
)
491 struct request_queue
*q
= rq
->q
;
492 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
493 struct blk_mq_hw_ctx
*hctx
= rq
->mq_hctx
;
494 const int sched_tag
= rq
->internal_tag
;
496 blk_crypto_free_request(rq
);
497 blk_pm_mark_last_busy(rq
);
499 if (rq
->tag
!= BLK_MQ_NO_TAG
)
500 blk_mq_put_tag(hctx
->tags
, ctx
, rq
->tag
);
501 if (sched_tag
!= BLK_MQ_NO_TAG
)
502 blk_mq_put_tag(hctx
->sched_tags
, ctx
, sched_tag
);
503 blk_mq_sched_restart(hctx
);
507 void blk_mq_free_request(struct request
*rq
)
509 struct request_queue
*q
= rq
->q
;
510 struct elevator_queue
*e
= q
->elevator
;
511 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
512 struct blk_mq_hw_ctx
*hctx
= rq
->mq_hctx
;
514 if (rq
->rq_flags
& RQF_ELVPRIV
) {
515 if (e
&& e
->type
->ops
.finish_request
)
516 e
->type
->ops
.finish_request(rq
);
518 put_io_context(rq
->elv
.icq
->ioc
);
523 ctx
->rq_completed
[rq_is_sync(rq
)]++;
524 if (rq
->rq_flags
& RQF_MQ_INFLIGHT
)
525 __blk_mq_dec_active_requests(hctx
);
527 if (unlikely(laptop_mode
&& !blk_rq_is_passthrough(rq
)))
528 laptop_io_completion(q
->backing_dev_info
);
532 WRITE_ONCE(rq
->state
, MQ_RQ_IDLE
);
533 if (refcount_dec_and_test(&rq
->ref
))
534 __blk_mq_free_request(rq
);
536 EXPORT_SYMBOL_GPL(blk_mq_free_request
);
538 inline void __blk_mq_end_request(struct request
*rq
, blk_status_t error
)
542 if (blk_mq_need_time_stamp(rq
))
543 now
= ktime_get_ns();
545 if (rq
->rq_flags
& RQF_STATS
) {
546 blk_mq_poll_stats_start(rq
->q
);
547 blk_stat_add(rq
, now
);
550 blk_mq_sched_completed_request(rq
, now
);
552 blk_account_io_done(rq
, now
);
555 rq_qos_done(rq
->q
, rq
);
556 rq
->end_io(rq
, error
);
558 blk_mq_free_request(rq
);
561 EXPORT_SYMBOL(__blk_mq_end_request
);
563 void blk_mq_end_request(struct request
*rq
, blk_status_t error
)
565 if (blk_update_request(rq
, error
, blk_rq_bytes(rq
)))
567 __blk_mq_end_request(rq
, error
);
569 EXPORT_SYMBOL(blk_mq_end_request
);
571 static void blk_complete_reqs(struct llist_head
*list
)
573 struct llist_node
*entry
= llist_reverse_order(llist_del_all(list
));
574 struct request
*rq
, *next
;
576 llist_for_each_entry_safe(rq
, next
, entry
, ipi_list
)
577 rq
->q
->mq_ops
->complete(rq
);
580 static __latent_entropy
void blk_done_softirq(struct softirq_action
*h
)
582 blk_complete_reqs(this_cpu_ptr(&blk_cpu_done
));
585 static int blk_softirq_cpu_dead(unsigned int cpu
)
587 blk_complete_reqs(&per_cpu(blk_cpu_done
, cpu
));
591 static void __blk_mq_complete_request_remote(void *data
)
593 __raise_softirq_irqoff(BLOCK_SOFTIRQ
);
596 static inline bool blk_mq_complete_need_ipi(struct request
*rq
)
598 int cpu
= raw_smp_processor_id();
600 if (!IS_ENABLED(CONFIG_SMP
) ||
601 !test_bit(QUEUE_FLAG_SAME_COMP
, &rq
->q
->queue_flags
))
604 * With force threaded interrupts enabled, raising softirq from an SMP
605 * function call will always result in waking the ksoftirqd thread.
606 * This is probably worse than completing the request on a different
609 if (force_irqthreads
)
612 /* same CPU or cache domain? Complete locally */
613 if (cpu
== rq
->mq_ctx
->cpu
||
614 (!test_bit(QUEUE_FLAG_SAME_FORCE
, &rq
->q
->queue_flags
) &&
615 cpus_share_cache(cpu
, rq
->mq_ctx
->cpu
)))
618 /* don't try to IPI to an offline CPU */
619 return cpu_online(rq
->mq_ctx
->cpu
);
622 static void blk_mq_complete_send_ipi(struct request
*rq
)
624 struct llist_head
*list
;
627 cpu
= rq
->mq_ctx
->cpu
;
628 list
= &per_cpu(blk_cpu_done
, cpu
);
629 if (llist_add(&rq
->ipi_list
, list
)) {
630 INIT_CSD(&rq
->csd
, __blk_mq_complete_request_remote
, rq
);
631 smp_call_function_single_async(cpu
, &rq
->csd
);
635 static void blk_mq_raise_softirq(struct request
*rq
)
637 struct llist_head
*list
;
640 list
= this_cpu_ptr(&blk_cpu_done
);
641 if (llist_add(&rq
->ipi_list
, list
))
642 raise_softirq(BLOCK_SOFTIRQ
);
646 bool blk_mq_complete_request_remote(struct request
*rq
)
648 WRITE_ONCE(rq
->state
, MQ_RQ_COMPLETE
);
651 * For a polled request, always complete locallly, it's pointless
652 * to redirect the completion.
654 if (rq
->cmd_flags
& REQ_HIPRI
)
657 if (blk_mq_complete_need_ipi(rq
)) {
658 blk_mq_complete_send_ipi(rq
);
662 if (rq
->q
->nr_hw_queues
== 1) {
663 blk_mq_raise_softirq(rq
);
668 EXPORT_SYMBOL_GPL(blk_mq_complete_request_remote
);
671 * blk_mq_complete_request - end I/O on a request
672 * @rq: the request being processed
675 * Complete a request by scheduling the ->complete_rq operation.
677 void blk_mq_complete_request(struct request
*rq
)
679 if (!blk_mq_complete_request_remote(rq
))
680 rq
->q
->mq_ops
->complete(rq
);
682 EXPORT_SYMBOL(blk_mq_complete_request
);
684 static void hctx_unlock(struct blk_mq_hw_ctx
*hctx
, int srcu_idx
)
685 __releases(hctx
->srcu
)
687 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
))
690 srcu_read_unlock(hctx
->srcu
, srcu_idx
);
693 static void hctx_lock(struct blk_mq_hw_ctx
*hctx
, int *srcu_idx
)
694 __acquires(hctx
->srcu
)
696 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
697 /* shut up gcc false positive */
701 *srcu_idx
= srcu_read_lock(hctx
->srcu
);
705 * blk_mq_start_request - Start processing a request
706 * @rq: Pointer to request to be started
708 * Function used by device drivers to notify the block layer that a request
709 * is going to be processed now, so blk layer can do proper initializations
710 * such as starting the timeout timer.
712 void blk_mq_start_request(struct request
*rq
)
714 struct request_queue
*q
= rq
->q
;
716 trace_block_rq_issue(rq
);
718 if (test_bit(QUEUE_FLAG_STATS
, &q
->queue_flags
)) {
719 rq
->io_start_time_ns
= ktime_get_ns();
720 rq
->stats_sectors
= blk_rq_sectors(rq
);
721 rq
->rq_flags
|= RQF_STATS
;
725 WARN_ON_ONCE(blk_mq_rq_state(rq
) != MQ_RQ_IDLE
);
728 WRITE_ONCE(rq
->state
, MQ_RQ_IN_FLIGHT
);
730 #ifdef CONFIG_BLK_DEV_INTEGRITY
731 if (blk_integrity_rq(rq
) && req_op(rq
) == REQ_OP_WRITE
)
732 q
->integrity
.profile
->prepare_fn(rq
);
735 EXPORT_SYMBOL(blk_mq_start_request
);
737 static void __blk_mq_requeue_request(struct request
*rq
)
739 struct request_queue
*q
= rq
->q
;
741 blk_mq_put_driver_tag(rq
);
743 trace_block_rq_requeue(rq
);
744 rq_qos_requeue(q
, rq
);
746 if (blk_mq_request_started(rq
)) {
747 WRITE_ONCE(rq
->state
, MQ_RQ_IDLE
);
748 rq
->rq_flags
&= ~RQF_TIMED_OUT
;
752 void blk_mq_requeue_request(struct request
*rq
, bool kick_requeue_list
)
754 __blk_mq_requeue_request(rq
);
756 /* this request will be re-inserted to io scheduler queue */
757 blk_mq_sched_requeue_request(rq
);
759 BUG_ON(!list_empty(&rq
->queuelist
));
760 blk_mq_add_to_requeue_list(rq
, true, kick_requeue_list
);
762 EXPORT_SYMBOL(blk_mq_requeue_request
);
764 static void blk_mq_requeue_work(struct work_struct
*work
)
766 struct request_queue
*q
=
767 container_of(work
, struct request_queue
, requeue_work
.work
);
769 struct request
*rq
, *next
;
771 spin_lock_irq(&q
->requeue_lock
);
772 list_splice_init(&q
->requeue_list
, &rq_list
);
773 spin_unlock_irq(&q
->requeue_lock
);
775 list_for_each_entry_safe(rq
, next
, &rq_list
, queuelist
) {
776 if (!(rq
->rq_flags
& (RQF_SOFTBARRIER
| RQF_DONTPREP
)))
779 rq
->rq_flags
&= ~RQF_SOFTBARRIER
;
780 list_del_init(&rq
->queuelist
);
782 * If RQF_DONTPREP, rq has contained some driver specific
783 * data, so insert it to hctx dispatch list to avoid any
786 if (rq
->rq_flags
& RQF_DONTPREP
)
787 blk_mq_request_bypass_insert(rq
, false, false);
789 blk_mq_sched_insert_request(rq
, true, false, false);
792 while (!list_empty(&rq_list
)) {
793 rq
= list_entry(rq_list
.next
, struct request
, queuelist
);
794 list_del_init(&rq
->queuelist
);
795 blk_mq_sched_insert_request(rq
, false, false, false);
798 blk_mq_run_hw_queues(q
, false);
801 void blk_mq_add_to_requeue_list(struct request
*rq
, bool at_head
,
802 bool kick_requeue_list
)
804 struct request_queue
*q
= rq
->q
;
808 * We abuse this flag that is otherwise used by the I/O scheduler to
809 * request head insertion from the workqueue.
811 BUG_ON(rq
->rq_flags
& RQF_SOFTBARRIER
);
813 spin_lock_irqsave(&q
->requeue_lock
, flags
);
815 rq
->rq_flags
|= RQF_SOFTBARRIER
;
816 list_add(&rq
->queuelist
, &q
->requeue_list
);
818 list_add_tail(&rq
->queuelist
, &q
->requeue_list
);
820 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
822 if (kick_requeue_list
)
823 blk_mq_kick_requeue_list(q
);
826 void blk_mq_kick_requeue_list(struct request_queue
*q
)
828 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND
, &q
->requeue_work
, 0);
830 EXPORT_SYMBOL(blk_mq_kick_requeue_list
);
832 void blk_mq_delay_kick_requeue_list(struct request_queue
*q
,
835 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND
, &q
->requeue_work
,
836 msecs_to_jiffies(msecs
));
838 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list
);
840 struct request
*blk_mq_tag_to_rq(struct blk_mq_tags
*tags
, unsigned int tag
)
842 if (tag
< tags
->nr_tags
) {
843 prefetch(tags
->rqs
[tag
]);
844 return tags
->rqs
[tag
];
849 EXPORT_SYMBOL(blk_mq_tag_to_rq
);
851 static bool blk_mq_rq_inflight(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
,
852 void *priv
, bool reserved
)
855 * If we find a request that isn't idle and the queue matches,
856 * we know the queue is busy. Return false to stop the iteration.
858 if (blk_mq_request_started(rq
) && rq
->q
== hctx
->queue
) {
868 bool blk_mq_queue_inflight(struct request_queue
*q
)
872 blk_mq_queue_tag_busy_iter(q
, blk_mq_rq_inflight
, &busy
);
875 EXPORT_SYMBOL_GPL(blk_mq_queue_inflight
);
877 static void blk_mq_rq_timed_out(struct request
*req
, bool reserved
)
879 req
->rq_flags
|= RQF_TIMED_OUT
;
880 if (req
->q
->mq_ops
->timeout
) {
881 enum blk_eh_timer_return ret
;
883 ret
= req
->q
->mq_ops
->timeout(req
, reserved
);
884 if (ret
== BLK_EH_DONE
)
886 WARN_ON_ONCE(ret
!= BLK_EH_RESET_TIMER
);
892 static bool blk_mq_req_expired(struct request
*rq
, unsigned long *next
)
894 unsigned long deadline
;
896 if (blk_mq_rq_state(rq
) != MQ_RQ_IN_FLIGHT
)
898 if (rq
->rq_flags
& RQF_TIMED_OUT
)
901 deadline
= READ_ONCE(rq
->deadline
);
902 if (time_after_eq(jiffies
, deadline
))
907 else if (time_after(*next
, deadline
))
912 static bool blk_mq_check_expired(struct blk_mq_hw_ctx
*hctx
,
913 struct request
*rq
, void *priv
, bool reserved
)
915 unsigned long *next
= priv
;
918 * Just do a quick check if it is expired before locking the request in
919 * so we're not unnecessarilly synchronizing across CPUs.
921 if (!blk_mq_req_expired(rq
, next
))
925 * We have reason to believe the request may be expired. Take a
926 * reference on the request to lock this request lifetime into its
927 * currently allocated context to prevent it from being reallocated in
928 * the event the completion by-passes this timeout handler.
930 * If the reference was already released, then the driver beat the
931 * timeout handler to posting a natural completion.
933 if (!refcount_inc_not_zero(&rq
->ref
))
937 * The request is now locked and cannot be reallocated underneath the
938 * timeout handler's processing. Re-verify this exact request is truly
939 * expired; if it is not expired, then the request was completed and
940 * reallocated as a new request.
942 if (blk_mq_req_expired(rq
, next
))
943 blk_mq_rq_timed_out(rq
, reserved
);
945 if (is_flush_rq(rq
, hctx
))
947 else if (refcount_dec_and_test(&rq
->ref
))
948 __blk_mq_free_request(rq
);
953 static void blk_mq_timeout_work(struct work_struct
*work
)
955 struct request_queue
*q
=
956 container_of(work
, struct request_queue
, timeout_work
);
957 unsigned long next
= 0;
958 struct blk_mq_hw_ctx
*hctx
;
961 /* A deadlock might occur if a request is stuck requiring a
962 * timeout at the same time a queue freeze is waiting
963 * completion, since the timeout code would not be able to
964 * acquire the queue reference here.
966 * That's why we don't use blk_queue_enter here; instead, we use
967 * percpu_ref_tryget directly, because we need to be able to
968 * obtain a reference even in the short window between the queue
969 * starting to freeze, by dropping the first reference in
970 * blk_freeze_queue_start, and the moment the last request is
971 * consumed, marked by the instant q_usage_counter reaches
974 if (!percpu_ref_tryget(&q
->q_usage_counter
))
977 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_expired
, &next
);
980 mod_timer(&q
->timeout
, next
);
983 * Request timeouts are handled as a forward rolling timer. If
984 * we end up here it means that no requests are pending and
985 * also that no request has been pending for a while. Mark
988 queue_for_each_hw_ctx(q
, hctx
, i
) {
989 /* the hctx may be unmapped, so check it here */
990 if (blk_mq_hw_queue_mapped(hctx
))
991 blk_mq_tag_idle(hctx
);
997 struct flush_busy_ctx_data
{
998 struct blk_mq_hw_ctx
*hctx
;
999 struct list_head
*list
;
1002 static bool flush_busy_ctx(struct sbitmap
*sb
, unsigned int bitnr
, void *data
)
1004 struct flush_busy_ctx_data
*flush_data
= data
;
1005 struct blk_mq_hw_ctx
*hctx
= flush_data
->hctx
;
1006 struct blk_mq_ctx
*ctx
= hctx
->ctxs
[bitnr
];
1007 enum hctx_type type
= hctx
->type
;
1009 spin_lock(&ctx
->lock
);
1010 list_splice_tail_init(&ctx
->rq_lists
[type
], flush_data
->list
);
1011 sbitmap_clear_bit(sb
, bitnr
);
1012 spin_unlock(&ctx
->lock
);
1017 * Process software queues that have been marked busy, splicing them
1018 * to the for-dispatch
1020 void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx
*hctx
, struct list_head
*list
)
1022 struct flush_busy_ctx_data data
= {
1027 sbitmap_for_each_set(&hctx
->ctx_map
, flush_busy_ctx
, &data
);
1029 EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs
);
1031 struct dispatch_rq_data
{
1032 struct blk_mq_hw_ctx
*hctx
;
1036 static bool dispatch_rq_from_ctx(struct sbitmap
*sb
, unsigned int bitnr
,
1039 struct dispatch_rq_data
*dispatch_data
= data
;
1040 struct blk_mq_hw_ctx
*hctx
= dispatch_data
->hctx
;
1041 struct blk_mq_ctx
*ctx
= hctx
->ctxs
[bitnr
];
1042 enum hctx_type type
= hctx
->type
;
1044 spin_lock(&ctx
->lock
);
1045 if (!list_empty(&ctx
->rq_lists
[type
])) {
1046 dispatch_data
->rq
= list_entry_rq(ctx
->rq_lists
[type
].next
);
1047 list_del_init(&dispatch_data
->rq
->queuelist
);
1048 if (list_empty(&ctx
->rq_lists
[type
]))
1049 sbitmap_clear_bit(sb
, bitnr
);
1051 spin_unlock(&ctx
->lock
);
1053 return !dispatch_data
->rq
;
1056 struct request
*blk_mq_dequeue_from_ctx(struct blk_mq_hw_ctx
*hctx
,
1057 struct blk_mq_ctx
*start
)
1059 unsigned off
= start
? start
->index_hw
[hctx
->type
] : 0;
1060 struct dispatch_rq_data data
= {
1065 __sbitmap_for_each_set(&hctx
->ctx_map
, off
,
1066 dispatch_rq_from_ctx
, &data
);
1071 static inline unsigned int queued_to_index(unsigned int queued
)
1076 return min(BLK_MQ_MAX_DISPATCH_ORDER
- 1, ilog2(queued
) + 1);
1079 static bool __blk_mq_get_driver_tag(struct request
*rq
)
1081 struct sbitmap_queue
*bt
= rq
->mq_hctx
->tags
->bitmap_tags
;
1082 unsigned int tag_offset
= rq
->mq_hctx
->tags
->nr_reserved_tags
;
1085 blk_mq_tag_busy(rq
->mq_hctx
);
1087 if (blk_mq_tag_is_reserved(rq
->mq_hctx
->sched_tags
, rq
->internal_tag
)) {
1088 bt
= rq
->mq_hctx
->tags
->breserved_tags
;
1091 if (!hctx_may_queue(rq
->mq_hctx
, bt
))
1095 tag
= __sbitmap_queue_get(bt
);
1096 if (tag
== BLK_MQ_NO_TAG
)
1099 rq
->tag
= tag
+ tag_offset
;
1103 static bool blk_mq_get_driver_tag(struct request
*rq
)
1105 struct blk_mq_hw_ctx
*hctx
= rq
->mq_hctx
;
1107 if (rq
->tag
== BLK_MQ_NO_TAG
&& !__blk_mq_get_driver_tag(rq
))
1110 if ((hctx
->flags
& BLK_MQ_F_TAG_QUEUE_SHARED
) &&
1111 !(rq
->rq_flags
& RQF_MQ_INFLIGHT
)) {
1112 rq
->rq_flags
|= RQF_MQ_INFLIGHT
;
1113 __blk_mq_inc_active_requests(hctx
);
1115 hctx
->tags
->rqs
[rq
->tag
] = rq
;
1119 static int blk_mq_dispatch_wake(wait_queue_entry_t
*wait
, unsigned mode
,
1120 int flags
, void *key
)
1122 struct blk_mq_hw_ctx
*hctx
;
1124 hctx
= container_of(wait
, struct blk_mq_hw_ctx
, dispatch_wait
);
1126 spin_lock(&hctx
->dispatch_wait_lock
);
1127 if (!list_empty(&wait
->entry
)) {
1128 struct sbitmap_queue
*sbq
;
1130 list_del_init(&wait
->entry
);
1131 sbq
= hctx
->tags
->bitmap_tags
;
1132 atomic_dec(&sbq
->ws_active
);
1134 spin_unlock(&hctx
->dispatch_wait_lock
);
1136 blk_mq_run_hw_queue(hctx
, true);
1141 * Mark us waiting for a tag. For shared tags, this involves hooking us into
1142 * the tag wakeups. For non-shared tags, we can simply mark us needing a
1143 * restart. For both cases, take care to check the condition again after
1144 * marking us as waiting.
1146 static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx
*hctx
,
1149 struct sbitmap_queue
*sbq
= hctx
->tags
->bitmap_tags
;
1150 struct wait_queue_head
*wq
;
1151 wait_queue_entry_t
*wait
;
1154 if (!(hctx
->flags
& BLK_MQ_F_TAG_QUEUE_SHARED
)) {
1155 blk_mq_sched_mark_restart_hctx(hctx
);
1158 * It's possible that a tag was freed in the window between the
1159 * allocation failure and adding the hardware queue to the wait
1162 * Don't clear RESTART here, someone else could have set it.
1163 * At most this will cost an extra queue run.
1165 return blk_mq_get_driver_tag(rq
);
1168 wait
= &hctx
->dispatch_wait
;
1169 if (!list_empty_careful(&wait
->entry
))
1172 wq
= &bt_wait_ptr(sbq
, hctx
)->wait
;
1174 spin_lock_irq(&wq
->lock
);
1175 spin_lock(&hctx
->dispatch_wait_lock
);
1176 if (!list_empty(&wait
->entry
)) {
1177 spin_unlock(&hctx
->dispatch_wait_lock
);
1178 spin_unlock_irq(&wq
->lock
);
1182 atomic_inc(&sbq
->ws_active
);
1183 wait
->flags
&= ~WQ_FLAG_EXCLUSIVE
;
1184 __add_wait_queue(wq
, wait
);
1187 * It's possible that a tag was freed in the window between the
1188 * allocation failure and adding the hardware queue to the wait
1191 ret
= blk_mq_get_driver_tag(rq
);
1193 spin_unlock(&hctx
->dispatch_wait_lock
);
1194 spin_unlock_irq(&wq
->lock
);
1199 * We got a tag, remove ourselves from the wait queue to ensure
1200 * someone else gets the wakeup.
1202 list_del_init(&wait
->entry
);
1203 atomic_dec(&sbq
->ws_active
);
1204 spin_unlock(&hctx
->dispatch_wait_lock
);
1205 spin_unlock_irq(&wq
->lock
);
1210 #define BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT 8
1211 #define BLK_MQ_DISPATCH_BUSY_EWMA_FACTOR 4
1213 * Update dispatch busy with the Exponential Weighted Moving Average(EWMA):
1214 * - EWMA is one simple way to compute running average value
1215 * - weight(7/8 and 1/8) is applied so that it can decrease exponentially
1216 * - take 4 as factor for avoiding to get too small(0) result, and this
1217 * factor doesn't matter because EWMA decreases exponentially
1219 static void blk_mq_update_dispatch_busy(struct blk_mq_hw_ctx
*hctx
, bool busy
)
1223 if (hctx
->queue
->elevator
)
1226 ewma
= hctx
->dispatch_busy
;
1231 ewma
*= BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT
- 1;
1233 ewma
+= 1 << BLK_MQ_DISPATCH_BUSY_EWMA_FACTOR
;
1234 ewma
/= BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT
;
1236 hctx
->dispatch_busy
= ewma
;
1239 #define BLK_MQ_RESOURCE_DELAY 3 /* ms units */
1241 static void blk_mq_handle_dev_resource(struct request
*rq
,
1242 struct list_head
*list
)
1244 struct request
*next
=
1245 list_first_entry_or_null(list
, struct request
, queuelist
);
1248 * If an I/O scheduler has been configured and we got a driver tag for
1249 * the next request already, free it.
1252 blk_mq_put_driver_tag(next
);
1254 list_add(&rq
->queuelist
, list
);
1255 __blk_mq_requeue_request(rq
);
1258 static void blk_mq_handle_zone_resource(struct request
*rq
,
1259 struct list_head
*zone_list
)
1262 * If we end up here it is because we cannot dispatch a request to a
1263 * specific zone due to LLD level zone-write locking or other zone
1264 * related resource not being available. In this case, set the request
1265 * aside in zone_list for retrying it later.
1267 list_add(&rq
->queuelist
, zone_list
);
1268 __blk_mq_requeue_request(rq
);
1271 enum prep_dispatch
{
1273 PREP_DISPATCH_NO_TAG
,
1274 PREP_DISPATCH_NO_BUDGET
,
1277 static enum prep_dispatch
blk_mq_prep_dispatch_rq(struct request
*rq
,
1280 struct blk_mq_hw_ctx
*hctx
= rq
->mq_hctx
;
1281 int budget_token
= -1;
1284 budget_token
= blk_mq_get_dispatch_budget(rq
->q
);
1285 if (budget_token
< 0) {
1286 blk_mq_put_driver_tag(rq
);
1287 return PREP_DISPATCH_NO_BUDGET
;
1289 blk_mq_set_rq_budget_token(rq
, budget_token
);
1292 if (!blk_mq_get_driver_tag(rq
)) {
1294 * The initial allocation attempt failed, so we need to
1295 * rerun the hardware queue when a tag is freed. The
1296 * waitqueue takes care of that. If the queue is run
1297 * before we add this entry back on the dispatch list,
1298 * we'll re-run it below.
1300 if (!blk_mq_mark_tag_wait(hctx
, rq
)) {
1302 * All budgets not got from this function will be put
1303 * together during handling partial dispatch
1306 blk_mq_put_dispatch_budget(rq
->q
, budget_token
);
1307 return PREP_DISPATCH_NO_TAG
;
1311 return PREP_DISPATCH_OK
;
1314 /* release all allocated budgets before calling to blk_mq_dispatch_rq_list */
1315 static void blk_mq_release_budgets(struct request_queue
*q
,
1316 struct list_head
*list
)
1320 list_for_each_entry(rq
, list
, queuelist
) {
1321 int budget_token
= blk_mq_get_rq_budget_token(rq
);
1323 if (budget_token
>= 0)
1324 blk_mq_put_dispatch_budget(q
, budget_token
);
1329 * Returns true if we did some work AND can potentially do more.
1331 bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx
*hctx
, struct list_head
*list
,
1332 unsigned int nr_budgets
)
1334 enum prep_dispatch prep
;
1335 struct request_queue
*q
= hctx
->queue
;
1336 struct request
*rq
, *nxt
;
1338 blk_status_t ret
= BLK_STS_OK
;
1339 LIST_HEAD(zone_list
);
1341 if (list_empty(list
))
1345 * Now process all the entries, sending them to the driver.
1347 errors
= queued
= 0;
1349 struct blk_mq_queue_data bd
;
1351 rq
= list_first_entry(list
, struct request
, queuelist
);
1353 WARN_ON_ONCE(hctx
!= rq
->mq_hctx
);
1354 prep
= blk_mq_prep_dispatch_rq(rq
, !nr_budgets
);
1355 if (prep
!= PREP_DISPATCH_OK
)
1358 list_del_init(&rq
->queuelist
);
1363 * Flag last if we have no more requests, or if we have more
1364 * but can't assign a driver tag to it.
1366 if (list_empty(list
))
1369 nxt
= list_first_entry(list
, struct request
, queuelist
);
1370 bd
.last
= !blk_mq_get_driver_tag(nxt
);
1374 * once the request is queued to lld, no need to cover the
1379 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1384 case BLK_STS_RESOURCE
:
1385 case BLK_STS_DEV_RESOURCE
:
1386 blk_mq_handle_dev_resource(rq
, list
);
1388 case BLK_STS_ZONE_RESOURCE
:
1390 * Move the request to zone_list and keep going through
1391 * the dispatch list to find more requests the drive can
1394 blk_mq_handle_zone_resource(rq
, &zone_list
);
1398 blk_mq_end_request(rq
, ret
);
1400 } while (!list_empty(list
));
1402 if (!list_empty(&zone_list
))
1403 list_splice_tail_init(&zone_list
, list
);
1405 hctx
->dispatched
[queued_to_index(queued
)]++;
1407 /* If we didn't flush the entire list, we could have told the driver
1408 * there was more coming, but that turned out to be a lie.
1410 if ((!list_empty(list
) || errors
) && q
->mq_ops
->commit_rqs
&& queued
)
1411 q
->mq_ops
->commit_rqs(hctx
);
1413 * Any items that need requeuing? Stuff them into hctx->dispatch,
1414 * that is where we will continue on next queue run.
1416 if (!list_empty(list
)) {
1418 /* For non-shared tags, the RESTART check will suffice */
1419 bool no_tag
= prep
== PREP_DISPATCH_NO_TAG
&&
1420 (hctx
->flags
& BLK_MQ_F_TAG_QUEUE_SHARED
);
1421 bool no_budget_avail
= prep
== PREP_DISPATCH_NO_BUDGET
;
1424 blk_mq_release_budgets(q
, list
);
1426 spin_lock(&hctx
->lock
);
1427 list_splice_tail_init(list
, &hctx
->dispatch
);
1428 spin_unlock(&hctx
->lock
);
1431 * Order adding requests to hctx->dispatch and checking
1432 * SCHED_RESTART flag. The pair of this smp_mb() is the one
1433 * in blk_mq_sched_restart(). Avoid restart code path to
1434 * miss the new added requests to hctx->dispatch, meantime
1435 * SCHED_RESTART is observed here.
1440 * If SCHED_RESTART was set by the caller of this function and
1441 * it is no longer set that means that it was cleared by another
1442 * thread and hence that a queue rerun is needed.
1444 * If 'no_tag' is set, that means that we failed getting
1445 * a driver tag with an I/O scheduler attached. If our dispatch
1446 * waitqueue is no longer active, ensure that we run the queue
1447 * AFTER adding our entries back to the list.
1449 * If no I/O scheduler has been configured it is possible that
1450 * the hardware queue got stopped and restarted before requests
1451 * were pushed back onto the dispatch list. Rerun the queue to
1452 * avoid starvation. Notes:
1453 * - blk_mq_run_hw_queue() checks whether or not a queue has
1454 * been stopped before rerunning a queue.
1455 * - Some but not all block drivers stop a queue before
1456 * returning BLK_STS_RESOURCE. Two exceptions are scsi-mq
1459 * If driver returns BLK_STS_RESOURCE and SCHED_RESTART
1460 * bit is set, run queue after a delay to avoid IO stalls
1461 * that could otherwise occur if the queue is idle. We'll do
1462 * similar if we couldn't get budget and SCHED_RESTART is set.
1464 needs_restart
= blk_mq_sched_needs_restart(hctx
);
1465 if (!needs_restart
||
1466 (no_tag
&& list_empty_careful(&hctx
->dispatch_wait
.entry
)))
1467 blk_mq_run_hw_queue(hctx
, true);
1468 else if (needs_restart
&& (ret
== BLK_STS_RESOURCE
||
1470 blk_mq_delay_run_hw_queue(hctx
, BLK_MQ_RESOURCE_DELAY
);
1472 blk_mq_update_dispatch_busy(hctx
, true);
1475 blk_mq_update_dispatch_busy(hctx
, false);
1477 return (queued
+ errors
) != 0;
1481 * __blk_mq_run_hw_queue - Run a hardware queue.
1482 * @hctx: Pointer to the hardware queue to run.
1484 * Send pending requests to the hardware.
1486 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1491 * We can't run the queue inline with ints disabled. Ensure that
1492 * we catch bad users of this early.
1494 WARN_ON_ONCE(in_interrupt());
1496 might_sleep_if(hctx
->flags
& BLK_MQ_F_BLOCKING
);
1498 hctx_lock(hctx
, &srcu_idx
);
1499 blk_mq_sched_dispatch_requests(hctx
);
1500 hctx_unlock(hctx
, srcu_idx
);
1503 static inline int blk_mq_first_mapped_cpu(struct blk_mq_hw_ctx
*hctx
)
1505 int cpu
= cpumask_first_and(hctx
->cpumask
, cpu_online_mask
);
1507 if (cpu
>= nr_cpu_ids
)
1508 cpu
= cpumask_first(hctx
->cpumask
);
1513 * It'd be great if the workqueue API had a way to pass
1514 * in a mask and had some smarts for more clever placement.
1515 * For now we just round-robin here, switching for every
1516 * BLK_MQ_CPU_WORK_BATCH queued items.
1518 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx
*hctx
)
1521 int next_cpu
= hctx
->next_cpu
;
1523 if (hctx
->queue
->nr_hw_queues
== 1)
1524 return WORK_CPU_UNBOUND
;
1526 if (--hctx
->next_cpu_batch
<= 0) {
1528 next_cpu
= cpumask_next_and(next_cpu
, hctx
->cpumask
,
1530 if (next_cpu
>= nr_cpu_ids
)
1531 next_cpu
= blk_mq_first_mapped_cpu(hctx
);
1532 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
1536 * Do unbound schedule if we can't find a online CPU for this hctx,
1537 * and it should only happen in the path of handling CPU DEAD.
1539 if (!cpu_online(next_cpu
)) {
1546 * Make sure to re-select CPU next time once after CPUs
1547 * in hctx->cpumask become online again.
1549 hctx
->next_cpu
= next_cpu
;
1550 hctx
->next_cpu_batch
= 1;
1551 return WORK_CPU_UNBOUND
;
1554 hctx
->next_cpu
= next_cpu
;
1559 * __blk_mq_delay_run_hw_queue - Run (or schedule to run) a hardware queue.
1560 * @hctx: Pointer to the hardware queue to run.
1561 * @async: If we want to run the queue asynchronously.
1562 * @msecs: Milliseconds of delay to wait before running the queue.
1564 * If !@async, try to run the queue now. Else, run the queue asynchronously and
1565 * with a delay of @msecs.
1567 static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
,
1568 unsigned long msecs
)
1570 if (unlikely(blk_mq_hctx_stopped(hctx
)))
1573 if (!async
&& !(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1574 int cpu
= get_cpu();
1575 if (cpumask_test_cpu(cpu
, hctx
->cpumask
)) {
1576 __blk_mq_run_hw_queue(hctx
);
1584 kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx
), &hctx
->run_work
,
1585 msecs_to_jiffies(msecs
));
1589 * blk_mq_delay_run_hw_queue - Run a hardware queue asynchronously.
1590 * @hctx: Pointer to the hardware queue to run.
1591 * @msecs: Milliseconds of delay to wait before running the queue.
1593 * Run a hardware queue asynchronously with a delay of @msecs.
1595 void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, unsigned long msecs
)
1597 __blk_mq_delay_run_hw_queue(hctx
, true, msecs
);
1599 EXPORT_SYMBOL(blk_mq_delay_run_hw_queue
);
1602 * blk_mq_run_hw_queue - Start to run a hardware queue.
1603 * @hctx: Pointer to the hardware queue to run.
1604 * @async: If we want to run the queue asynchronously.
1606 * Check if the request queue is not in a quiesced state and if there are
1607 * pending requests to be sent. If this is true, run the queue to send requests
1610 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1616 * When queue is quiesced, we may be switching io scheduler, or
1617 * updating nr_hw_queues, or other things, and we can't run queue
1618 * any more, even __blk_mq_hctx_has_pending() can't be called safely.
1620 * And queue will be rerun in blk_mq_unquiesce_queue() if it is
1623 hctx_lock(hctx
, &srcu_idx
);
1624 need_run
= !blk_queue_quiesced(hctx
->queue
) &&
1625 blk_mq_hctx_has_pending(hctx
);
1626 hctx_unlock(hctx
, srcu_idx
);
1629 __blk_mq_delay_run_hw_queue(hctx
, async
, 0);
1631 EXPORT_SYMBOL(blk_mq_run_hw_queue
);
1634 * Is the request queue handled by an IO scheduler that does not respect
1635 * hardware queues when dispatching?
1637 static bool blk_mq_has_sqsched(struct request_queue
*q
)
1639 struct elevator_queue
*e
= q
->elevator
;
1641 if (e
&& e
->type
->ops
.dispatch_request
&&
1642 !(e
->type
->elevator_features
& ELEVATOR_F_MQ_AWARE
))
1648 * Return prefered queue to dispatch from (if any) for non-mq aware IO
1651 static struct blk_mq_hw_ctx
*blk_mq_get_sq_hctx(struct request_queue
*q
)
1653 struct blk_mq_hw_ctx
*hctx
;
1656 * If the IO scheduler does not respect hardware queues when
1657 * dispatching, we just don't bother with multiple HW queues and
1658 * dispatch from hctx for the current CPU since running multiple queues
1659 * just causes lock contention inside the scheduler and pointless cache
1662 hctx
= blk_mq_map_queue_type(q
, HCTX_TYPE_DEFAULT
,
1663 raw_smp_processor_id());
1664 if (!blk_mq_hctx_stopped(hctx
))
1670 * blk_mq_run_hw_queues - Run all hardware queues in a request queue.
1671 * @q: Pointer to the request queue to run.
1672 * @async: If we want to run the queue asynchronously.
1674 void blk_mq_run_hw_queues(struct request_queue
*q
, bool async
)
1676 struct blk_mq_hw_ctx
*hctx
, *sq_hctx
;
1680 if (blk_mq_has_sqsched(q
))
1681 sq_hctx
= blk_mq_get_sq_hctx(q
);
1682 queue_for_each_hw_ctx(q
, hctx
, i
) {
1683 if (blk_mq_hctx_stopped(hctx
))
1686 * Dispatch from this hctx either if there's no hctx preferred
1687 * by IO scheduler or if it has requests that bypass the
1690 if (!sq_hctx
|| sq_hctx
== hctx
||
1691 !list_empty_careful(&hctx
->dispatch
))
1692 blk_mq_run_hw_queue(hctx
, async
);
1695 EXPORT_SYMBOL(blk_mq_run_hw_queues
);
1698 * blk_mq_delay_run_hw_queues - Run all hardware queues asynchronously.
1699 * @q: Pointer to the request queue to run.
1700 * @msecs: Milliseconds of delay to wait before running the queues.
1702 void blk_mq_delay_run_hw_queues(struct request_queue
*q
, unsigned long msecs
)
1704 struct blk_mq_hw_ctx
*hctx
, *sq_hctx
;
1708 if (blk_mq_has_sqsched(q
))
1709 sq_hctx
= blk_mq_get_sq_hctx(q
);
1710 queue_for_each_hw_ctx(q
, hctx
, i
) {
1711 if (blk_mq_hctx_stopped(hctx
))
1714 * Dispatch from this hctx either if there's no hctx preferred
1715 * by IO scheduler or if it has requests that bypass the
1718 if (!sq_hctx
|| sq_hctx
== hctx
||
1719 !list_empty_careful(&hctx
->dispatch
))
1720 blk_mq_delay_run_hw_queue(hctx
, msecs
);
1723 EXPORT_SYMBOL(blk_mq_delay_run_hw_queues
);
1726 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1727 * @q: request queue.
1729 * The caller is responsible for serializing this function against
1730 * blk_mq_{start,stop}_hw_queue().
1732 bool blk_mq_queue_stopped(struct request_queue
*q
)
1734 struct blk_mq_hw_ctx
*hctx
;
1737 queue_for_each_hw_ctx(q
, hctx
, i
)
1738 if (blk_mq_hctx_stopped(hctx
))
1743 EXPORT_SYMBOL(blk_mq_queue_stopped
);
1746 * This function is often used for pausing .queue_rq() by driver when
1747 * there isn't enough resource or some conditions aren't satisfied, and
1748 * BLK_STS_RESOURCE is usually returned.
1750 * We do not guarantee that dispatch can be drained or blocked
1751 * after blk_mq_stop_hw_queue() returns. Please use
1752 * blk_mq_quiesce_queue() for that requirement.
1754 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1756 cancel_delayed_work(&hctx
->run_work
);
1758 set_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1760 EXPORT_SYMBOL(blk_mq_stop_hw_queue
);
1763 * This function is often used for pausing .queue_rq() by driver when
1764 * there isn't enough resource or some conditions aren't satisfied, and
1765 * BLK_STS_RESOURCE is usually returned.
1767 * We do not guarantee that dispatch can be drained or blocked
1768 * after blk_mq_stop_hw_queues() returns. Please use
1769 * blk_mq_quiesce_queue() for that requirement.
1771 void blk_mq_stop_hw_queues(struct request_queue
*q
)
1773 struct blk_mq_hw_ctx
*hctx
;
1776 queue_for_each_hw_ctx(q
, hctx
, i
)
1777 blk_mq_stop_hw_queue(hctx
);
1779 EXPORT_SYMBOL(blk_mq_stop_hw_queues
);
1781 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1783 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1785 blk_mq_run_hw_queue(hctx
, false);
1787 EXPORT_SYMBOL(blk_mq_start_hw_queue
);
1789 void blk_mq_start_hw_queues(struct request_queue
*q
)
1791 struct blk_mq_hw_ctx
*hctx
;
1794 queue_for_each_hw_ctx(q
, hctx
, i
)
1795 blk_mq_start_hw_queue(hctx
);
1797 EXPORT_SYMBOL(blk_mq_start_hw_queues
);
1799 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1801 if (!blk_mq_hctx_stopped(hctx
))
1804 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1805 blk_mq_run_hw_queue(hctx
, async
);
1807 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue
);
1809 void blk_mq_start_stopped_hw_queues(struct request_queue
*q
, bool async
)
1811 struct blk_mq_hw_ctx
*hctx
;
1814 queue_for_each_hw_ctx(q
, hctx
, i
)
1815 blk_mq_start_stopped_hw_queue(hctx
, async
);
1817 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues
);
1819 static void blk_mq_run_work_fn(struct work_struct
*work
)
1821 struct blk_mq_hw_ctx
*hctx
;
1823 hctx
= container_of(work
, struct blk_mq_hw_ctx
, run_work
.work
);
1826 * If we are stopped, don't run the queue.
1828 if (blk_mq_hctx_stopped(hctx
))
1831 __blk_mq_run_hw_queue(hctx
);
1834 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx
*hctx
,
1838 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1839 enum hctx_type type
= hctx
->type
;
1841 lockdep_assert_held(&ctx
->lock
);
1843 trace_block_rq_insert(rq
);
1846 list_add(&rq
->queuelist
, &ctx
->rq_lists
[type
]);
1848 list_add_tail(&rq
->queuelist
, &ctx
->rq_lists
[type
]);
1851 void __blk_mq_insert_request(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
,
1854 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1856 lockdep_assert_held(&ctx
->lock
);
1858 __blk_mq_insert_req_list(hctx
, rq
, at_head
);
1859 blk_mq_hctx_mark_pending(hctx
, ctx
);
1863 * blk_mq_request_bypass_insert - Insert a request at dispatch list.
1864 * @rq: Pointer to request to be inserted.
1865 * @at_head: true if the request should be inserted at the head of the list.
1866 * @run_queue: If we should run the hardware queue after inserting the request.
1868 * Should only be used carefully, when the caller knows we want to
1869 * bypass a potential IO scheduler on the target device.
1871 void blk_mq_request_bypass_insert(struct request
*rq
, bool at_head
,
1874 struct blk_mq_hw_ctx
*hctx
= rq
->mq_hctx
;
1876 spin_lock(&hctx
->lock
);
1878 list_add(&rq
->queuelist
, &hctx
->dispatch
);
1880 list_add_tail(&rq
->queuelist
, &hctx
->dispatch
);
1881 spin_unlock(&hctx
->lock
);
1884 blk_mq_run_hw_queue(hctx
, false);
1887 void blk_mq_insert_requests(struct blk_mq_hw_ctx
*hctx
, struct blk_mq_ctx
*ctx
,
1888 struct list_head
*list
)
1892 enum hctx_type type
= hctx
->type
;
1895 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1898 list_for_each_entry(rq
, list
, queuelist
) {
1899 BUG_ON(rq
->mq_ctx
!= ctx
);
1900 trace_block_rq_insert(rq
);
1903 spin_lock(&ctx
->lock
);
1904 list_splice_tail_init(list
, &ctx
->rq_lists
[type
]);
1905 blk_mq_hctx_mark_pending(hctx
, ctx
);
1906 spin_unlock(&ctx
->lock
);
1909 static int plug_rq_cmp(void *priv
, const struct list_head
*a
,
1910 const struct list_head
*b
)
1912 struct request
*rqa
= container_of(a
, struct request
, queuelist
);
1913 struct request
*rqb
= container_of(b
, struct request
, queuelist
);
1915 if (rqa
->mq_ctx
!= rqb
->mq_ctx
)
1916 return rqa
->mq_ctx
> rqb
->mq_ctx
;
1917 if (rqa
->mq_hctx
!= rqb
->mq_hctx
)
1918 return rqa
->mq_hctx
> rqb
->mq_hctx
;
1920 return blk_rq_pos(rqa
) > blk_rq_pos(rqb
);
1923 void blk_mq_flush_plug_list(struct blk_plug
*plug
, bool from_schedule
)
1927 if (list_empty(&plug
->mq_list
))
1929 list_splice_init(&plug
->mq_list
, &list
);
1931 if (plug
->rq_count
> 2 && plug
->multiple_queues
)
1932 list_sort(NULL
, &list
, plug_rq_cmp
);
1937 struct list_head rq_list
;
1938 struct request
*rq
, *head_rq
= list_entry_rq(list
.next
);
1939 struct list_head
*pos
= &head_rq
->queuelist
; /* skip first */
1940 struct blk_mq_hw_ctx
*this_hctx
= head_rq
->mq_hctx
;
1941 struct blk_mq_ctx
*this_ctx
= head_rq
->mq_ctx
;
1942 unsigned int depth
= 1;
1944 list_for_each_continue(pos
, &list
) {
1945 rq
= list_entry_rq(pos
);
1947 if (rq
->mq_hctx
!= this_hctx
|| rq
->mq_ctx
!= this_ctx
)
1952 list_cut_before(&rq_list
, &list
, pos
);
1953 trace_block_unplug(head_rq
->q
, depth
, !from_schedule
);
1954 blk_mq_sched_insert_requests(this_hctx
, this_ctx
, &rq_list
,
1956 } while(!list_empty(&list
));
1959 static void blk_mq_bio_to_request(struct request
*rq
, struct bio
*bio
,
1960 unsigned int nr_segs
)
1964 if (bio
->bi_opf
& REQ_RAHEAD
)
1965 rq
->cmd_flags
|= REQ_FAILFAST_MASK
;
1967 rq
->__sector
= bio
->bi_iter
.bi_sector
;
1968 rq
->write_hint
= bio
->bi_write_hint
;
1969 blk_rq_bio_prep(rq
, bio
, nr_segs
);
1971 /* This can't fail, since GFP_NOIO includes __GFP_DIRECT_RECLAIM. */
1972 err
= blk_crypto_rq_bio_prep(rq
, bio
, GFP_NOIO
);
1975 blk_account_io_start(rq
);
1978 static blk_status_t
__blk_mq_issue_directly(struct blk_mq_hw_ctx
*hctx
,
1980 blk_qc_t
*cookie
, bool last
)
1982 struct request_queue
*q
= rq
->q
;
1983 struct blk_mq_queue_data bd
= {
1987 blk_qc_t new_cookie
;
1990 new_cookie
= request_to_qc_t(hctx
, rq
);
1993 * For OK queue, we are done. For error, caller may kill it.
1994 * Any other error (busy), just add it to our list as we
1995 * previously would have done.
1997 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
2000 blk_mq_update_dispatch_busy(hctx
, false);
2001 *cookie
= new_cookie
;
2003 case BLK_STS_RESOURCE
:
2004 case BLK_STS_DEV_RESOURCE
:
2005 blk_mq_update_dispatch_busy(hctx
, true);
2006 __blk_mq_requeue_request(rq
);
2009 blk_mq_update_dispatch_busy(hctx
, false);
2010 *cookie
= BLK_QC_T_NONE
;
2017 static blk_status_t
__blk_mq_try_issue_directly(struct blk_mq_hw_ctx
*hctx
,
2020 bool bypass_insert
, bool last
)
2022 struct request_queue
*q
= rq
->q
;
2023 bool run_queue
= true;
2027 * RCU or SRCU read lock is needed before checking quiesced flag.
2029 * When queue is stopped or quiesced, ignore 'bypass_insert' from
2030 * blk_mq_request_issue_directly(), and return BLK_STS_OK to caller,
2031 * and avoid driver to try to dispatch again.
2033 if (blk_mq_hctx_stopped(hctx
) || blk_queue_quiesced(q
)) {
2035 bypass_insert
= false;
2039 if (q
->elevator
&& !bypass_insert
)
2042 budget_token
= blk_mq_get_dispatch_budget(q
);
2043 if (budget_token
< 0)
2046 blk_mq_set_rq_budget_token(rq
, budget_token
);
2048 if (!blk_mq_get_driver_tag(rq
)) {
2049 blk_mq_put_dispatch_budget(q
, budget_token
);
2053 return __blk_mq_issue_directly(hctx
, rq
, cookie
, last
);
2056 return BLK_STS_RESOURCE
;
2058 blk_mq_sched_insert_request(rq
, false, run_queue
, false);
2064 * blk_mq_try_issue_directly - Try to send a request directly to device driver.
2065 * @hctx: Pointer of the associated hardware queue.
2066 * @rq: Pointer to request to be sent.
2067 * @cookie: Request queue cookie.
2069 * If the device has enough resources to accept a new request now, send the
2070 * request directly to device driver. Else, insert at hctx->dispatch queue, so
2071 * we can try send it another time in the future. Requests inserted at this
2072 * queue have higher priority.
2074 static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx
*hctx
,
2075 struct request
*rq
, blk_qc_t
*cookie
)
2080 might_sleep_if(hctx
->flags
& BLK_MQ_F_BLOCKING
);
2082 hctx_lock(hctx
, &srcu_idx
);
2084 ret
= __blk_mq_try_issue_directly(hctx
, rq
, cookie
, false, true);
2085 if (ret
== BLK_STS_RESOURCE
|| ret
== BLK_STS_DEV_RESOURCE
)
2086 blk_mq_request_bypass_insert(rq
, false, true);
2087 else if (ret
!= BLK_STS_OK
)
2088 blk_mq_end_request(rq
, ret
);
2090 hctx_unlock(hctx
, srcu_idx
);
2093 blk_status_t
blk_mq_request_issue_directly(struct request
*rq
, bool last
)
2097 blk_qc_t unused_cookie
;
2098 struct blk_mq_hw_ctx
*hctx
= rq
->mq_hctx
;
2100 hctx_lock(hctx
, &srcu_idx
);
2101 ret
= __blk_mq_try_issue_directly(hctx
, rq
, &unused_cookie
, true, last
);
2102 hctx_unlock(hctx
, srcu_idx
);
2107 void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx
*hctx
,
2108 struct list_head
*list
)
2113 while (!list_empty(list
)) {
2115 struct request
*rq
= list_first_entry(list
, struct request
,
2118 list_del_init(&rq
->queuelist
);
2119 ret
= blk_mq_request_issue_directly(rq
, list_empty(list
));
2120 if (ret
!= BLK_STS_OK
) {
2121 if (ret
== BLK_STS_RESOURCE
||
2122 ret
== BLK_STS_DEV_RESOURCE
) {
2123 blk_mq_request_bypass_insert(rq
, false,
2127 blk_mq_end_request(rq
, ret
);
2134 * If we didn't flush the entire list, we could have told
2135 * the driver there was more coming, but that turned out to
2138 if ((!list_empty(list
) || errors
) &&
2139 hctx
->queue
->mq_ops
->commit_rqs
&& queued
)
2140 hctx
->queue
->mq_ops
->commit_rqs(hctx
);
2143 static void blk_add_rq_to_plug(struct blk_plug
*plug
, struct request
*rq
)
2145 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
2147 if (!plug
->multiple_queues
&& !list_is_singular(&plug
->mq_list
)) {
2148 struct request
*tmp
;
2150 tmp
= list_first_entry(&plug
->mq_list
, struct request
,
2152 if (tmp
->q
!= rq
->q
)
2153 plug
->multiple_queues
= true;
2158 * blk_mq_submit_bio - Create and send a request to block device.
2159 * @bio: Bio pointer.
2161 * Builds up a request structure from @q and @bio and send to the device. The
2162 * request may not be queued directly to hardware if:
2163 * * This request can be merged with another one
2164 * * We want to place request at plug queue for possible future merging
2165 * * There is an IO scheduler active at this queue
2167 * It will not queue the request if there is an error with the bio, or at the
2170 * Returns: Request queue cookie.
2172 blk_qc_t
blk_mq_submit_bio(struct bio
*bio
)
2174 struct request_queue
*q
= bio
->bi_bdev
->bd_disk
->queue
;
2175 const int is_sync
= op_is_sync(bio
->bi_opf
);
2176 const int is_flush_fua
= op_is_flush(bio
->bi_opf
);
2177 struct blk_mq_alloc_data data
= {
2181 struct blk_plug
*plug
;
2182 struct request
*same_queue_rq
= NULL
;
2183 unsigned int nr_segs
;
2188 blk_queue_bounce(q
, &bio
);
2189 __blk_queue_split(&bio
, &nr_segs
);
2191 if (!bio_integrity_prep(bio
))
2194 if (!is_flush_fua
&& !blk_queue_nomerges(q
) &&
2195 blk_attempt_plug_merge(q
, bio
, nr_segs
, &same_queue_rq
))
2198 if (blk_mq_sched_bio_merge(q
, bio
, nr_segs
))
2201 rq_qos_throttle(q
, bio
);
2203 hipri
= bio
->bi_opf
& REQ_HIPRI
;
2205 data
.cmd_flags
= bio
->bi_opf
;
2206 rq
= __blk_mq_alloc_request(&data
);
2207 if (unlikely(!rq
)) {
2208 rq_qos_cleanup(q
, bio
);
2209 if (bio
->bi_opf
& REQ_NOWAIT
)
2210 bio_wouldblock_error(bio
);
2214 trace_block_getrq(bio
);
2216 rq_qos_track(q
, rq
, bio
);
2218 cookie
= request_to_qc_t(data
.hctx
, rq
);
2220 blk_mq_bio_to_request(rq
, bio
, nr_segs
);
2222 ret
= blk_crypto_init_request(rq
);
2223 if (ret
!= BLK_STS_OK
) {
2224 bio
->bi_status
= ret
;
2226 blk_mq_free_request(rq
);
2227 return BLK_QC_T_NONE
;
2230 plug
= blk_mq_plug(q
, bio
);
2231 if (unlikely(is_flush_fua
)) {
2232 /* Bypass scheduler for flush requests */
2233 blk_insert_flush(rq
);
2234 blk_mq_run_hw_queue(data
.hctx
, true);
2235 } else if (plug
&& (q
->nr_hw_queues
== 1 ||
2236 blk_mq_is_sbitmap_shared(rq
->mq_hctx
->flags
) ||
2237 q
->mq_ops
->commit_rqs
|| !blk_queue_nonrot(q
))) {
2239 * Use plugging if we have a ->commit_rqs() hook as well, as
2240 * we know the driver uses bd->last in a smart fashion.
2242 * Use normal plugging if this disk is slow HDD, as sequential
2243 * IO may benefit a lot from plug merging.
2245 unsigned int request_count
= plug
->rq_count
;
2246 struct request
*last
= NULL
;
2249 trace_block_plug(q
);
2251 last
= list_entry_rq(plug
->mq_list
.prev
);
2253 if (request_count
>= BLK_MAX_REQUEST_COUNT
|| (last
&&
2254 blk_rq_bytes(last
) >= BLK_PLUG_FLUSH_SIZE
)) {
2255 blk_flush_plug_list(plug
, false);
2256 trace_block_plug(q
);
2259 blk_add_rq_to_plug(plug
, rq
);
2260 } else if (q
->elevator
) {
2261 /* Insert the request at the IO scheduler queue */
2262 blk_mq_sched_insert_request(rq
, false, true, true);
2263 } else if (plug
&& !blk_queue_nomerges(q
)) {
2265 * We do limited plugging. If the bio can be merged, do that.
2266 * Otherwise the existing request in the plug list will be
2267 * issued. So the plug list will have one request at most
2268 * The plug list might get flushed before this. If that happens,
2269 * the plug list is empty, and same_queue_rq is invalid.
2271 if (list_empty(&plug
->mq_list
))
2272 same_queue_rq
= NULL
;
2273 if (same_queue_rq
) {
2274 list_del_init(&same_queue_rq
->queuelist
);
2277 blk_add_rq_to_plug(plug
, rq
);
2278 trace_block_plug(q
);
2280 if (same_queue_rq
) {
2281 data
.hctx
= same_queue_rq
->mq_hctx
;
2282 trace_block_unplug(q
, 1, true);
2283 blk_mq_try_issue_directly(data
.hctx
, same_queue_rq
,
2286 } else if ((q
->nr_hw_queues
> 1 && is_sync
) ||
2287 !data
.hctx
->dispatch_busy
) {
2289 * There is no scheduler and we can try to send directly
2292 blk_mq_try_issue_directly(data
.hctx
, rq
, &cookie
);
2295 blk_mq_sched_insert_request(rq
, false, true, true);
2299 return BLK_QC_T_NONE
;
2303 return BLK_QC_T_NONE
;
2306 void blk_mq_free_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
2307 unsigned int hctx_idx
)
2311 if (tags
->rqs
&& set
->ops
->exit_request
) {
2314 for (i
= 0; i
< tags
->nr_tags
; i
++) {
2315 struct request
*rq
= tags
->static_rqs
[i
];
2319 set
->ops
->exit_request(set
, rq
, hctx_idx
);
2320 tags
->static_rqs
[i
] = NULL
;
2324 while (!list_empty(&tags
->page_list
)) {
2325 page
= list_first_entry(&tags
->page_list
, struct page
, lru
);
2326 list_del_init(&page
->lru
);
2328 * Remove kmemleak object previously allocated in
2329 * blk_mq_alloc_rqs().
2331 kmemleak_free(page_address(page
));
2332 __free_pages(page
, page
->private);
2336 void blk_mq_free_rq_map(struct blk_mq_tags
*tags
, unsigned int flags
)
2340 kfree(tags
->static_rqs
);
2341 tags
->static_rqs
= NULL
;
2343 blk_mq_free_tags(tags
, flags
);
2346 struct blk_mq_tags
*blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
,
2347 unsigned int hctx_idx
,
2348 unsigned int nr_tags
,
2349 unsigned int reserved_tags
,
2352 struct blk_mq_tags
*tags
;
2355 node
= blk_mq_hw_queue_to_node(&set
->map
[HCTX_TYPE_DEFAULT
], hctx_idx
);
2356 if (node
== NUMA_NO_NODE
)
2357 node
= set
->numa_node
;
2359 tags
= blk_mq_init_tags(nr_tags
, reserved_tags
, node
, flags
);
2363 tags
->rqs
= kcalloc_node(nr_tags
, sizeof(struct request
*),
2364 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
2367 blk_mq_free_tags(tags
, flags
);
2371 tags
->static_rqs
= kcalloc_node(nr_tags
, sizeof(struct request
*),
2372 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
2374 if (!tags
->static_rqs
) {
2376 blk_mq_free_tags(tags
, flags
);
2383 static size_t order_to_size(unsigned int order
)
2385 return (size_t)PAGE_SIZE
<< order
;
2388 static int blk_mq_init_request(struct blk_mq_tag_set
*set
, struct request
*rq
,
2389 unsigned int hctx_idx
, int node
)
2393 if (set
->ops
->init_request
) {
2394 ret
= set
->ops
->init_request(set
, rq
, hctx_idx
, node
);
2399 WRITE_ONCE(rq
->state
, MQ_RQ_IDLE
);
2403 int blk_mq_alloc_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
2404 unsigned int hctx_idx
, unsigned int depth
)
2406 unsigned int i
, j
, entries_per_page
, max_order
= 4;
2407 size_t rq_size
, left
;
2410 node
= blk_mq_hw_queue_to_node(&set
->map
[HCTX_TYPE_DEFAULT
], hctx_idx
);
2411 if (node
== NUMA_NO_NODE
)
2412 node
= set
->numa_node
;
2414 INIT_LIST_HEAD(&tags
->page_list
);
2417 * rq_size is the size of the request plus driver payload, rounded
2418 * to the cacheline size
2420 rq_size
= round_up(sizeof(struct request
) + set
->cmd_size
,
2422 left
= rq_size
* depth
;
2424 for (i
= 0; i
< depth
; ) {
2425 int this_order
= max_order
;
2430 while (this_order
&& left
< order_to_size(this_order
- 1))
2434 page
= alloc_pages_node(node
,
2435 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
| __GFP_ZERO
,
2441 if (order_to_size(this_order
) < rq_size
)
2448 page
->private = this_order
;
2449 list_add_tail(&page
->lru
, &tags
->page_list
);
2451 p
= page_address(page
);
2453 * Allow kmemleak to scan these pages as they contain pointers
2454 * to additional allocations like via ops->init_request().
2456 kmemleak_alloc(p
, order_to_size(this_order
), 1, GFP_NOIO
);
2457 entries_per_page
= order_to_size(this_order
) / rq_size
;
2458 to_do
= min(entries_per_page
, depth
- i
);
2459 left
-= to_do
* rq_size
;
2460 for (j
= 0; j
< to_do
; j
++) {
2461 struct request
*rq
= p
;
2463 tags
->static_rqs
[i
] = rq
;
2464 if (blk_mq_init_request(set
, rq
, hctx_idx
, node
)) {
2465 tags
->static_rqs
[i
] = NULL
;
2476 blk_mq_free_rqs(set
, tags
, hctx_idx
);
2480 struct rq_iter_data
{
2481 struct blk_mq_hw_ctx
*hctx
;
2485 static bool blk_mq_has_request(struct request
*rq
, void *data
, bool reserved
)
2487 struct rq_iter_data
*iter_data
= data
;
2489 if (rq
->mq_hctx
!= iter_data
->hctx
)
2491 iter_data
->has_rq
= true;
2495 static bool blk_mq_hctx_has_requests(struct blk_mq_hw_ctx
*hctx
)
2497 struct blk_mq_tags
*tags
= hctx
->sched_tags
?
2498 hctx
->sched_tags
: hctx
->tags
;
2499 struct rq_iter_data data
= {
2503 blk_mq_all_tag_iter(tags
, blk_mq_has_request
, &data
);
2507 static inline bool blk_mq_last_cpu_in_hctx(unsigned int cpu
,
2508 struct blk_mq_hw_ctx
*hctx
)
2510 if (cpumask_next_and(-1, hctx
->cpumask
, cpu_online_mask
) != cpu
)
2512 if (cpumask_next_and(cpu
, hctx
->cpumask
, cpu_online_mask
) < nr_cpu_ids
)
2517 static int blk_mq_hctx_notify_offline(unsigned int cpu
, struct hlist_node
*node
)
2519 struct blk_mq_hw_ctx
*hctx
= hlist_entry_safe(node
,
2520 struct blk_mq_hw_ctx
, cpuhp_online
);
2522 if (!cpumask_test_cpu(cpu
, hctx
->cpumask
) ||
2523 !blk_mq_last_cpu_in_hctx(cpu
, hctx
))
2527 * Prevent new request from being allocated on the current hctx.
2529 * The smp_mb__after_atomic() Pairs with the implied barrier in
2530 * test_and_set_bit_lock in sbitmap_get(). Ensures the inactive flag is
2531 * seen once we return from the tag allocator.
2533 set_bit(BLK_MQ_S_INACTIVE
, &hctx
->state
);
2534 smp_mb__after_atomic();
2537 * Try to grab a reference to the queue and wait for any outstanding
2538 * requests. If we could not grab a reference the queue has been
2539 * frozen and there are no requests.
2541 if (percpu_ref_tryget(&hctx
->queue
->q_usage_counter
)) {
2542 while (blk_mq_hctx_has_requests(hctx
))
2544 percpu_ref_put(&hctx
->queue
->q_usage_counter
);
2550 static int blk_mq_hctx_notify_online(unsigned int cpu
, struct hlist_node
*node
)
2552 struct blk_mq_hw_ctx
*hctx
= hlist_entry_safe(node
,
2553 struct blk_mq_hw_ctx
, cpuhp_online
);
2555 if (cpumask_test_cpu(cpu
, hctx
->cpumask
))
2556 clear_bit(BLK_MQ_S_INACTIVE
, &hctx
->state
);
2561 * 'cpu' is going away. splice any existing rq_list entries from this
2562 * software queue to the hw queue dispatch list, and ensure that it
2565 static int blk_mq_hctx_notify_dead(unsigned int cpu
, struct hlist_node
*node
)
2567 struct blk_mq_hw_ctx
*hctx
;
2568 struct blk_mq_ctx
*ctx
;
2570 enum hctx_type type
;
2572 hctx
= hlist_entry_safe(node
, struct blk_mq_hw_ctx
, cpuhp_dead
);
2573 if (!cpumask_test_cpu(cpu
, hctx
->cpumask
))
2576 ctx
= __blk_mq_get_ctx(hctx
->queue
, cpu
);
2579 spin_lock(&ctx
->lock
);
2580 if (!list_empty(&ctx
->rq_lists
[type
])) {
2581 list_splice_init(&ctx
->rq_lists
[type
], &tmp
);
2582 blk_mq_hctx_clear_pending(hctx
, ctx
);
2584 spin_unlock(&ctx
->lock
);
2586 if (list_empty(&tmp
))
2589 spin_lock(&hctx
->lock
);
2590 list_splice_tail_init(&tmp
, &hctx
->dispatch
);
2591 spin_unlock(&hctx
->lock
);
2593 blk_mq_run_hw_queue(hctx
, true);
2597 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx
*hctx
)
2599 if (!(hctx
->flags
& BLK_MQ_F_STACKING
))
2600 cpuhp_state_remove_instance_nocalls(CPUHP_AP_BLK_MQ_ONLINE
,
2601 &hctx
->cpuhp_online
);
2602 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD
,
2606 /* hctx->ctxs will be freed in queue's release handler */
2607 static void blk_mq_exit_hctx(struct request_queue
*q
,
2608 struct blk_mq_tag_set
*set
,
2609 struct blk_mq_hw_ctx
*hctx
, unsigned int hctx_idx
)
2611 if (blk_mq_hw_queue_mapped(hctx
))
2612 blk_mq_tag_idle(hctx
);
2614 if (set
->ops
->exit_request
)
2615 set
->ops
->exit_request(set
, hctx
->fq
->flush_rq
, hctx_idx
);
2617 if (set
->ops
->exit_hctx
)
2618 set
->ops
->exit_hctx(hctx
, hctx_idx
);
2620 blk_mq_remove_cpuhp(hctx
);
2622 spin_lock(&q
->unused_hctx_lock
);
2623 list_add(&hctx
->hctx_list
, &q
->unused_hctx_list
);
2624 spin_unlock(&q
->unused_hctx_lock
);
2627 static void blk_mq_exit_hw_queues(struct request_queue
*q
,
2628 struct blk_mq_tag_set
*set
, int nr_queue
)
2630 struct blk_mq_hw_ctx
*hctx
;
2633 queue_for_each_hw_ctx(q
, hctx
, i
) {
2636 blk_mq_debugfs_unregister_hctx(hctx
);
2637 blk_mq_exit_hctx(q
, set
, hctx
, i
);
2641 static int blk_mq_hw_ctx_size(struct blk_mq_tag_set
*tag_set
)
2643 int hw_ctx_size
= sizeof(struct blk_mq_hw_ctx
);
2645 BUILD_BUG_ON(ALIGN(offsetof(struct blk_mq_hw_ctx
, srcu
),
2646 __alignof__(struct blk_mq_hw_ctx
)) !=
2647 sizeof(struct blk_mq_hw_ctx
));
2649 if (tag_set
->flags
& BLK_MQ_F_BLOCKING
)
2650 hw_ctx_size
+= sizeof(struct srcu_struct
);
2655 static int blk_mq_init_hctx(struct request_queue
*q
,
2656 struct blk_mq_tag_set
*set
,
2657 struct blk_mq_hw_ctx
*hctx
, unsigned hctx_idx
)
2659 hctx
->queue_num
= hctx_idx
;
2661 if (!(hctx
->flags
& BLK_MQ_F_STACKING
))
2662 cpuhp_state_add_instance_nocalls(CPUHP_AP_BLK_MQ_ONLINE
,
2663 &hctx
->cpuhp_online
);
2664 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD
, &hctx
->cpuhp_dead
);
2666 hctx
->tags
= set
->tags
[hctx_idx
];
2668 if (set
->ops
->init_hctx
&&
2669 set
->ops
->init_hctx(hctx
, set
->driver_data
, hctx_idx
))
2670 goto unregister_cpu_notifier
;
2672 if (blk_mq_init_request(set
, hctx
->fq
->flush_rq
, hctx_idx
,
2678 if (set
->ops
->exit_hctx
)
2679 set
->ops
->exit_hctx(hctx
, hctx_idx
);
2680 unregister_cpu_notifier
:
2681 blk_mq_remove_cpuhp(hctx
);
2685 static struct blk_mq_hw_ctx
*
2686 blk_mq_alloc_hctx(struct request_queue
*q
, struct blk_mq_tag_set
*set
,
2689 struct blk_mq_hw_ctx
*hctx
;
2690 gfp_t gfp
= GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
;
2692 hctx
= kzalloc_node(blk_mq_hw_ctx_size(set
), gfp
, node
);
2694 goto fail_alloc_hctx
;
2696 if (!zalloc_cpumask_var_node(&hctx
->cpumask
, gfp
, node
))
2699 atomic_set(&hctx
->nr_active
, 0);
2700 if (node
== NUMA_NO_NODE
)
2701 node
= set
->numa_node
;
2702 hctx
->numa_node
= node
;
2704 INIT_DELAYED_WORK(&hctx
->run_work
, blk_mq_run_work_fn
);
2705 spin_lock_init(&hctx
->lock
);
2706 INIT_LIST_HEAD(&hctx
->dispatch
);
2708 hctx
->flags
= set
->flags
& ~BLK_MQ_F_TAG_QUEUE_SHARED
;
2710 INIT_LIST_HEAD(&hctx
->hctx_list
);
2713 * Allocate space for all possible cpus to avoid allocation at
2716 hctx
->ctxs
= kmalloc_array_node(nr_cpu_ids
, sizeof(void *),
2721 if (sbitmap_init_node(&hctx
->ctx_map
, nr_cpu_ids
, ilog2(8),
2722 gfp
, node
, false, false))
2726 spin_lock_init(&hctx
->dispatch_wait_lock
);
2727 init_waitqueue_func_entry(&hctx
->dispatch_wait
, blk_mq_dispatch_wake
);
2728 INIT_LIST_HEAD(&hctx
->dispatch_wait
.entry
);
2730 hctx
->fq
= blk_alloc_flush_queue(hctx
->numa_node
, set
->cmd_size
, gfp
);
2734 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
2735 init_srcu_struct(hctx
->srcu
);
2736 blk_mq_hctx_kobj_init(hctx
);
2741 sbitmap_free(&hctx
->ctx_map
);
2745 free_cpumask_var(hctx
->cpumask
);
2752 static void blk_mq_init_cpu_queues(struct request_queue
*q
,
2753 unsigned int nr_hw_queues
)
2755 struct blk_mq_tag_set
*set
= q
->tag_set
;
2758 for_each_possible_cpu(i
) {
2759 struct blk_mq_ctx
*__ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
2760 struct blk_mq_hw_ctx
*hctx
;
2764 spin_lock_init(&__ctx
->lock
);
2765 for (k
= HCTX_TYPE_DEFAULT
; k
< HCTX_MAX_TYPES
; k
++)
2766 INIT_LIST_HEAD(&__ctx
->rq_lists
[k
]);
2771 * Set local node, IFF we have more than one hw queue. If
2772 * not, we remain on the home node of the device
2774 for (j
= 0; j
< set
->nr_maps
; j
++) {
2775 hctx
= blk_mq_map_queue_type(q
, j
, i
);
2776 if (nr_hw_queues
> 1 && hctx
->numa_node
== NUMA_NO_NODE
)
2777 hctx
->numa_node
= cpu_to_node(i
);
2782 static bool __blk_mq_alloc_map_and_request(struct blk_mq_tag_set
*set
,
2785 unsigned int flags
= set
->flags
;
2788 set
->tags
[hctx_idx
] = blk_mq_alloc_rq_map(set
, hctx_idx
,
2789 set
->queue_depth
, set
->reserved_tags
, flags
);
2790 if (!set
->tags
[hctx_idx
])
2793 ret
= blk_mq_alloc_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
,
2798 blk_mq_free_rq_map(set
->tags
[hctx_idx
], flags
);
2799 set
->tags
[hctx_idx
] = NULL
;
2803 static void blk_mq_free_map_and_requests(struct blk_mq_tag_set
*set
,
2804 unsigned int hctx_idx
)
2806 unsigned int flags
= set
->flags
;
2808 if (set
->tags
&& set
->tags
[hctx_idx
]) {
2809 blk_mq_free_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
);
2810 blk_mq_free_rq_map(set
->tags
[hctx_idx
], flags
);
2811 set
->tags
[hctx_idx
] = NULL
;
2815 static void blk_mq_map_swqueue(struct request_queue
*q
)
2817 unsigned int i
, j
, hctx_idx
;
2818 struct blk_mq_hw_ctx
*hctx
;
2819 struct blk_mq_ctx
*ctx
;
2820 struct blk_mq_tag_set
*set
= q
->tag_set
;
2822 queue_for_each_hw_ctx(q
, hctx
, i
) {
2823 cpumask_clear(hctx
->cpumask
);
2825 hctx
->dispatch_from
= NULL
;
2829 * Map software to hardware queues.
2831 * If the cpu isn't present, the cpu is mapped to first hctx.
2833 for_each_possible_cpu(i
) {
2835 ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
2836 for (j
= 0; j
< set
->nr_maps
; j
++) {
2837 if (!set
->map
[j
].nr_queues
) {
2838 ctx
->hctxs
[j
] = blk_mq_map_queue_type(q
,
2839 HCTX_TYPE_DEFAULT
, i
);
2842 hctx_idx
= set
->map
[j
].mq_map
[i
];
2843 /* unmapped hw queue can be remapped after CPU topo changed */
2844 if (!set
->tags
[hctx_idx
] &&
2845 !__blk_mq_alloc_map_and_request(set
, hctx_idx
)) {
2847 * If tags initialization fail for some hctx,
2848 * that hctx won't be brought online. In this
2849 * case, remap the current ctx to hctx[0] which
2850 * is guaranteed to always have tags allocated
2852 set
->map
[j
].mq_map
[i
] = 0;
2855 hctx
= blk_mq_map_queue_type(q
, j
, i
);
2856 ctx
->hctxs
[j
] = hctx
;
2858 * If the CPU is already set in the mask, then we've
2859 * mapped this one already. This can happen if
2860 * devices share queues across queue maps.
2862 if (cpumask_test_cpu(i
, hctx
->cpumask
))
2865 cpumask_set_cpu(i
, hctx
->cpumask
);
2867 ctx
->index_hw
[hctx
->type
] = hctx
->nr_ctx
;
2868 hctx
->ctxs
[hctx
->nr_ctx
++] = ctx
;
2871 * If the nr_ctx type overflows, we have exceeded the
2872 * amount of sw queues we can support.
2874 BUG_ON(!hctx
->nr_ctx
);
2877 for (; j
< HCTX_MAX_TYPES
; j
++)
2878 ctx
->hctxs
[j
] = blk_mq_map_queue_type(q
,
2879 HCTX_TYPE_DEFAULT
, i
);
2882 queue_for_each_hw_ctx(q
, hctx
, i
) {
2884 * If no software queues are mapped to this hardware queue,
2885 * disable it and free the request entries.
2887 if (!hctx
->nr_ctx
) {
2888 /* Never unmap queue 0. We need it as a
2889 * fallback in case of a new remap fails
2892 if (i
&& set
->tags
[i
])
2893 blk_mq_free_map_and_requests(set
, i
);
2899 hctx
->tags
= set
->tags
[i
];
2900 WARN_ON(!hctx
->tags
);
2903 * Set the map size to the number of mapped software queues.
2904 * This is more accurate and more efficient than looping
2905 * over all possibly mapped software queues.
2907 sbitmap_resize(&hctx
->ctx_map
, hctx
->nr_ctx
);
2910 * Initialize batch roundrobin counts
2912 hctx
->next_cpu
= blk_mq_first_mapped_cpu(hctx
);
2913 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
2918 * Caller needs to ensure that we're either frozen/quiesced, or that
2919 * the queue isn't live yet.
2921 static void queue_set_hctx_shared(struct request_queue
*q
, bool shared
)
2923 struct blk_mq_hw_ctx
*hctx
;
2926 queue_for_each_hw_ctx(q
, hctx
, i
) {
2928 hctx
->flags
|= BLK_MQ_F_TAG_QUEUE_SHARED
;
2930 hctx
->flags
&= ~BLK_MQ_F_TAG_QUEUE_SHARED
;
2934 static void blk_mq_update_tag_set_shared(struct blk_mq_tag_set
*set
,
2937 struct request_queue
*q
;
2939 lockdep_assert_held(&set
->tag_list_lock
);
2941 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
2942 blk_mq_freeze_queue(q
);
2943 queue_set_hctx_shared(q
, shared
);
2944 blk_mq_unfreeze_queue(q
);
2948 static void blk_mq_del_queue_tag_set(struct request_queue
*q
)
2950 struct blk_mq_tag_set
*set
= q
->tag_set
;
2952 mutex_lock(&set
->tag_list_lock
);
2953 list_del(&q
->tag_set_list
);
2954 if (list_is_singular(&set
->tag_list
)) {
2955 /* just transitioned to unshared */
2956 set
->flags
&= ~BLK_MQ_F_TAG_QUEUE_SHARED
;
2957 /* update existing queue */
2958 blk_mq_update_tag_set_shared(set
, false);
2960 mutex_unlock(&set
->tag_list_lock
);
2961 INIT_LIST_HEAD(&q
->tag_set_list
);
2964 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set
*set
,
2965 struct request_queue
*q
)
2967 mutex_lock(&set
->tag_list_lock
);
2970 * Check to see if we're transitioning to shared (from 1 to 2 queues).
2972 if (!list_empty(&set
->tag_list
) &&
2973 !(set
->flags
& BLK_MQ_F_TAG_QUEUE_SHARED
)) {
2974 set
->flags
|= BLK_MQ_F_TAG_QUEUE_SHARED
;
2975 /* update existing queue */
2976 blk_mq_update_tag_set_shared(set
, true);
2978 if (set
->flags
& BLK_MQ_F_TAG_QUEUE_SHARED
)
2979 queue_set_hctx_shared(q
, true);
2980 list_add_tail(&q
->tag_set_list
, &set
->tag_list
);
2982 mutex_unlock(&set
->tag_list_lock
);
2985 /* All allocations will be freed in release handler of q->mq_kobj */
2986 static int blk_mq_alloc_ctxs(struct request_queue
*q
)
2988 struct blk_mq_ctxs
*ctxs
;
2991 ctxs
= kzalloc(sizeof(*ctxs
), GFP_KERNEL
);
2995 ctxs
->queue_ctx
= alloc_percpu(struct blk_mq_ctx
);
2996 if (!ctxs
->queue_ctx
)
2999 for_each_possible_cpu(cpu
) {
3000 struct blk_mq_ctx
*ctx
= per_cpu_ptr(ctxs
->queue_ctx
, cpu
);
3004 q
->mq_kobj
= &ctxs
->kobj
;
3005 q
->queue_ctx
= ctxs
->queue_ctx
;
3014 * It is the actual release handler for mq, but we do it from
3015 * request queue's release handler for avoiding use-after-free
3016 * and headache because q->mq_kobj shouldn't have been introduced,
3017 * but we can't group ctx/kctx kobj without it.
3019 void blk_mq_release(struct request_queue
*q
)
3021 struct blk_mq_hw_ctx
*hctx
, *next
;
3024 queue_for_each_hw_ctx(q
, hctx
, i
)
3025 WARN_ON_ONCE(hctx
&& list_empty(&hctx
->hctx_list
));
3027 /* all hctx are in .unused_hctx_list now */
3028 list_for_each_entry_safe(hctx
, next
, &q
->unused_hctx_list
, hctx_list
) {
3029 list_del_init(&hctx
->hctx_list
);
3030 kobject_put(&hctx
->kobj
);
3033 kfree(q
->queue_hw_ctx
);
3036 * release .mq_kobj and sw queue's kobject now because
3037 * both share lifetime with request queue.
3039 blk_mq_sysfs_deinit(q
);
3042 struct request_queue
*blk_mq_init_queue_data(struct blk_mq_tag_set
*set
,
3045 struct request_queue
*uninit_q
, *q
;
3047 uninit_q
= blk_alloc_queue(set
->numa_node
);
3049 return ERR_PTR(-ENOMEM
);
3050 uninit_q
->queuedata
= queuedata
;
3053 * Initialize the queue without an elevator. device_add_disk() will do
3054 * the initialization.
3056 q
= blk_mq_init_allocated_queue(set
, uninit_q
, false);
3058 blk_cleanup_queue(uninit_q
);
3062 EXPORT_SYMBOL_GPL(blk_mq_init_queue_data
);
3064 struct request_queue
*blk_mq_init_queue(struct blk_mq_tag_set
*set
)
3066 return blk_mq_init_queue_data(set
, NULL
);
3068 EXPORT_SYMBOL(blk_mq_init_queue
);
3071 * Helper for setting up a queue with mq ops, given queue depth, and
3072 * the passed in mq ops flags.
3074 struct request_queue
*blk_mq_init_sq_queue(struct blk_mq_tag_set
*set
,
3075 const struct blk_mq_ops
*ops
,
3076 unsigned int queue_depth
,
3077 unsigned int set_flags
)
3079 struct request_queue
*q
;
3082 memset(set
, 0, sizeof(*set
));
3084 set
->nr_hw_queues
= 1;
3086 set
->queue_depth
= queue_depth
;
3087 set
->numa_node
= NUMA_NO_NODE
;
3088 set
->flags
= set_flags
;
3090 ret
= blk_mq_alloc_tag_set(set
);
3092 return ERR_PTR(ret
);
3094 q
= blk_mq_init_queue(set
);
3096 blk_mq_free_tag_set(set
);
3102 EXPORT_SYMBOL(blk_mq_init_sq_queue
);
3104 static struct blk_mq_hw_ctx
*blk_mq_alloc_and_init_hctx(
3105 struct blk_mq_tag_set
*set
, struct request_queue
*q
,
3106 int hctx_idx
, int node
)
3108 struct blk_mq_hw_ctx
*hctx
= NULL
, *tmp
;
3110 /* reuse dead hctx first */
3111 spin_lock(&q
->unused_hctx_lock
);
3112 list_for_each_entry(tmp
, &q
->unused_hctx_list
, hctx_list
) {
3113 if (tmp
->numa_node
== node
) {
3119 list_del_init(&hctx
->hctx_list
);
3120 spin_unlock(&q
->unused_hctx_lock
);
3123 hctx
= blk_mq_alloc_hctx(q
, set
, node
);
3127 if (blk_mq_init_hctx(q
, set
, hctx
, hctx_idx
))
3133 kobject_put(&hctx
->kobj
);
3138 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set
*set
,
3139 struct request_queue
*q
)
3142 struct blk_mq_hw_ctx
**hctxs
= q
->queue_hw_ctx
;
3144 if (q
->nr_hw_queues
< set
->nr_hw_queues
) {
3145 struct blk_mq_hw_ctx
**new_hctxs
;
3147 new_hctxs
= kcalloc_node(set
->nr_hw_queues
,
3148 sizeof(*new_hctxs
), GFP_KERNEL
,
3153 memcpy(new_hctxs
, hctxs
, q
->nr_hw_queues
*
3155 q
->queue_hw_ctx
= new_hctxs
;
3160 /* protect against switching io scheduler */
3161 mutex_lock(&q
->sysfs_lock
);
3162 for (i
= 0; i
< set
->nr_hw_queues
; i
++) {
3164 struct blk_mq_hw_ctx
*hctx
;
3166 node
= blk_mq_hw_queue_to_node(&set
->map
[HCTX_TYPE_DEFAULT
], i
);
3168 * If the hw queue has been mapped to another numa node,
3169 * we need to realloc the hctx. If allocation fails, fallback
3170 * to use the previous one.
3172 if (hctxs
[i
] && (hctxs
[i
]->numa_node
== node
))
3175 hctx
= blk_mq_alloc_and_init_hctx(set
, q
, i
, node
);
3178 blk_mq_exit_hctx(q
, set
, hctxs
[i
], i
);
3182 pr_warn("Allocate new hctx on node %d fails,\
3183 fallback to previous one on node %d\n",
3184 node
, hctxs
[i
]->numa_node
);
3190 * Increasing nr_hw_queues fails. Free the newly allocated
3191 * hctxs and keep the previous q->nr_hw_queues.
3193 if (i
!= set
->nr_hw_queues
) {
3194 j
= q
->nr_hw_queues
;
3198 end
= q
->nr_hw_queues
;
3199 q
->nr_hw_queues
= set
->nr_hw_queues
;
3202 for (; j
< end
; j
++) {
3203 struct blk_mq_hw_ctx
*hctx
= hctxs
[j
];
3207 blk_mq_free_map_and_requests(set
, j
);
3208 blk_mq_exit_hctx(q
, set
, hctx
, j
);
3212 mutex_unlock(&q
->sysfs_lock
);
3215 struct request_queue
*blk_mq_init_allocated_queue(struct blk_mq_tag_set
*set
,
3216 struct request_queue
*q
,
3219 /* mark the queue as mq asap */
3220 q
->mq_ops
= set
->ops
;
3222 q
->poll_cb
= blk_stat_alloc_callback(blk_mq_poll_stats_fn
,
3223 blk_mq_poll_stats_bkt
,
3224 BLK_MQ_POLL_STATS_BKTS
, q
);
3228 if (blk_mq_alloc_ctxs(q
))
3231 /* init q->mq_kobj and sw queues' kobjects */
3232 blk_mq_sysfs_init(q
);
3234 INIT_LIST_HEAD(&q
->unused_hctx_list
);
3235 spin_lock_init(&q
->unused_hctx_lock
);
3237 blk_mq_realloc_hw_ctxs(set
, q
);
3238 if (!q
->nr_hw_queues
)
3241 INIT_WORK(&q
->timeout_work
, blk_mq_timeout_work
);
3242 blk_queue_rq_timeout(q
, set
->timeout
? set
->timeout
: 30 * HZ
);
3246 q
->queue_flags
|= QUEUE_FLAG_MQ_DEFAULT
;
3247 if (set
->nr_maps
> HCTX_TYPE_POLL
&&
3248 set
->map
[HCTX_TYPE_POLL
].nr_queues
)
3249 blk_queue_flag_set(QUEUE_FLAG_POLL
, q
);
3251 q
->sg_reserved_size
= INT_MAX
;
3253 INIT_DELAYED_WORK(&q
->requeue_work
, blk_mq_requeue_work
);
3254 INIT_LIST_HEAD(&q
->requeue_list
);
3255 spin_lock_init(&q
->requeue_lock
);
3257 q
->nr_requests
= set
->queue_depth
;
3260 * Default to classic polling
3262 q
->poll_nsec
= BLK_MQ_POLL_CLASSIC
;
3264 blk_mq_init_cpu_queues(q
, set
->nr_hw_queues
);
3265 blk_mq_add_queue_tag_set(set
, q
);
3266 blk_mq_map_swqueue(q
);
3269 elevator_init_mq(q
);
3274 kfree(q
->queue_hw_ctx
);
3275 q
->nr_hw_queues
= 0;
3276 blk_mq_sysfs_deinit(q
);
3278 blk_stat_free_callback(q
->poll_cb
);
3282 return ERR_PTR(-ENOMEM
);
3284 EXPORT_SYMBOL(blk_mq_init_allocated_queue
);
3286 /* tags can _not_ be used after returning from blk_mq_exit_queue */
3287 void blk_mq_exit_queue(struct request_queue
*q
)
3289 struct blk_mq_tag_set
*set
= q
->tag_set
;
3291 /* Checks hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED. */
3292 blk_mq_exit_hw_queues(q
, set
, set
->nr_hw_queues
);
3293 /* May clear BLK_MQ_F_TAG_QUEUE_SHARED in hctx->flags. */
3294 blk_mq_del_queue_tag_set(q
);
3297 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
3301 for (i
= 0; i
< set
->nr_hw_queues
; i
++) {
3302 if (!__blk_mq_alloc_map_and_request(set
, i
))
3311 blk_mq_free_map_and_requests(set
, i
);
3317 * Allocate the request maps associated with this tag_set. Note that this
3318 * may reduce the depth asked for, if memory is tight. set->queue_depth
3319 * will be updated to reflect the allocated depth.
3321 static int blk_mq_alloc_map_and_requests(struct blk_mq_tag_set
*set
)
3326 depth
= set
->queue_depth
;
3328 err
= __blk_mq_alloc_rq_maps(set
);
3332 set
->queue_depth
>>= 1;
3333 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
) {
3337 } while (set
->queue_depth
);
3339 if (!set
->queue_depth
|| err
) {
3340 pr_err("blk-mq: failed to allocate request map\n");
3344 if (depth
!= set
->queue_depth
)
3345 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
3346 depth
, set
->queue_depth
);
3351 static int blk_mq_update_queue_map(struct blk_mq_tag_set
*set
)
3354 * blk_mq_map_queues() and multiple .map_queues() implementations
3355 * expect that set->map[HCTX_TYPE_DEFAULT].nr_queues is set to the
3356 * number of hardware queues.
3358 if (set
->nr_maps
== 1)
3359 set
->map
[HCTX_TYPE_DEFAULT
].nr_queues
= set
->nr_hw_queues
;
3361 if (set
->ops
->map_queues
&& !is_kdump_kernel()) {
3365 * transport .map_queues is usually done in the following
3368 * for (queue = 0; queue < set->nr_hw_queues; queue++) {
3369 * mask = get_cpu_mask(queue)
3370 * for_each_cpu(cpu, mask)
3371 * set->map[x].mq_map[cpu] = queue;
3374 * When we need to remap, the table has to be cleared for
3375 * killing stale mapping since one CPU may not be mapped
3378 for (i
= 0; i
< set
->nr_maps
; i
++)
3379 blk_mq_clear_mq_map(&set
->map
[i
]);
3381 return set
->ops
->map_queues(set
);
3383 BUG_ON(set
->nr_maps
> 1);
3384 return blk_mq_map_queues(&set
->map
[HCTX_TYPE_DEFAULT
]);
3388 static int blk_mq_realloc_tag_set_tags(struct blk_mq_tag_set
*set
,
3389 int cur_nr_hw_queues
, int new_nr_hw_queues
)
3391 struct blk_mq_tags
**new_tags
;
3393 if (cur_nr_hw_queues
>= new_nr_hw_queues
)
3396 new_tags
= kcalloc_node(new_nr_hw_queues
, sizeof(struct blk_mq_tags
*),
3397 GFP_KERNEL
, set
->numa_node
);
3402 memcpy(new_tags
, set
->tags
, cur_nr_hw_queues
*
3403 sizeof(*set
->tags
));
3405 set
->tags
= new_tags
;
3406 set
->nr_hw_queues
= new_nr_hw_queues
;
3411 static int blk_mq_alloc_tag_set_tags(struct blk_mq_tag_set
*set
,
3412 int new_nr_hw_queues
)
3414 return blk_mq_realloc_tag_set_tags(set
, 0, new_nr_hw_queues
);
3418 * Alloc a tag set to be associated with one or more request queues.
3419 * May fail with EINVAL for various error conditions. May adjust the
3420 * requested depth down, if it's too large. In that case, the set
3421 * value will be stored in set->queue_depth.
3423 int blk_mq_alloc_tag_set(struct blk_mq_tag_set
*set
)
3427 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH
> 1 << BLK_MQ_UNIQUE_TAG_BITS
);
3429 if (!set
->nr_hw_queues
)
3431 if (!set
->queue_depth
)
3433 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
)
3436 if (!set
->ops
->queue_rq
)
3439 if (!set
->ops
->get_budget
^ !set
->ops
->put_budget
)
3442 if (set
->queue_depth
> BLK_MQ_MAX_DEPTH
) {
3443 pr_info("blk-mq: reduced tag depth to %u\n",
3445 set
->queue_depth
= BLK_MQ_MAX_DEPTH
;
3450 else if (set
->nr_maps
> HCTX_MAX_TYPES
)
3454 * If a crashdump is active, then we are potentially in a very
3455 * memory constrained environment. Limit us to 1 queue and
3456 * 64 tags to prevent using too much memory.
3458 if (is_kdump_kernel()) {
3459 set
->nr_hw_queues
= 1;
3461 set
->queue_depth
= min(64U, set
->queue_depth
);
3464 * There is no use for more h/w queues than cpus if we just have
3467 if (set
->nr_maps
== 1 && set
->nr_hw_queues
> nr_cpu_ids
)
3468 set
->nr_hw_queues
= nr_cpu_ids
;
3470 if (blk_mq_alloc_tag_set_tags(set
, set
->nr_hw_queues
) < 0)
3474 for (i
= 0; i
< set
->nr_maps
; i
++) {
3475 set
->map
[i
].mq_map
= kcalloc_node(nr_cpu_ids
,
3476 sizeof(set
->map
[i
].mq_map
[0]),
3477 GFP_KERNEL
, set
->numa_node
);
3478 if (!set
->map
[i
].mq_map
)
3479 goto out_free_mq_map
;
3480 set
->map
[i
].nr_queues
= is_kdump_kernel() ? 1 : set
->nr_hw_queues
;
3483 ret
= blk_mq_update_queue_map(set
);
3485 goto out_free_mq_map
;
3487 ret
= blk_mq_alloc_map_and_requests(set
);
3489 goto out_free_mq_map
;
3491 if (blk_mq_is_sbitmap_shared(set
->flags
)) {
3492 atomic_set(&set
->active_queues_shared_sbitmap
, 0);
3494 if (blk_mq_init_shared_sbitmap(set
, set
->flags
)) {
3496 goto out_free_mq_rq_maps
;
3500 mutex_init(&set
->tag_list_lock
);
3501 INIT_LIST_HEAD(&set
->tag_list
);
3505 out_free_mq_rq_maps
:
3506 for (i
= 0; i
< set
->nr_hw_queues
; i
++)
3507 blk_mq_free_map_and_requests(set
, i
);
3509 for (i
= 0; i
< set
->nr_maps
; i
++) {
3510 kfree(set
->map
[i
].mq_map
);
3511 set
->map
[i
].mq_map
= NULL
;
3517 EXPORT_SYMBOL(blk_mq_alloc_tag_set
);
3519 void blk_mq_free_tag_set(struct blk_mq_tag_set
*set
)
3523 for (i
= 0; i
< set
->nr_hw_queues
; i
++)
3524 blk_mq_free_map_and_requests(set
, i
);
3526 if (blk_mq_is_sbitmap_shared(set
->flags
))
3527 blk_mq_exit_shared_sbitmap(set
);
3529 for (j
= 0; j
< set
->nr_maps
; j
++) {
3530 kfree(set
->map
[j
].mq_map
);
3531 set
->map
[j
].mq_map
= NULL
;
3537 EXPORT_SYMBOL(blk_mq_free_tag_set
);
3539 int blk_mq_update_nr_requests(struct request_queue
*q
, unsigned int nr
)
3541 struct blk_mq_tag_set
*set
= q
->tag_set
;
3542 struct blk_mq_hw_ctx
*hctx
;
3548 if (q
->nr_requests
== nr
)
3551 blk_mq_freeze_queue(q
);
3552 blk_mq_quiesce_queue(q
);
3555 queue_for_each_hw_ctx(q
, hctx
, i
) {
3559 * If we're using an MQ scheduler, just update the scheduler
3560 * queue depth. This is similar to what the old code would do.
3562 if (!hctx
->sched_tags
) {
3563 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->tags
, nr
,
3565 if (!ret
&& blk_mq_is_sbitmap_shared(set
->flags
))
3566 blk_mq_tag_resize_shared_sbitmap(set
, nr
);
3568 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->sched_tags
,
3573 if (q
->elevator
&& q
->elevator
->type
->ops
.depth_updated
)
3574 q
->elevator
->type
->ops
.depth_updated(hctx
);
3578 q
->nr_requests
= nr
;
3580 blk_mq_unquiesce_queue(q
);
3581 blk_mq_unfreeze_queue(q
);
3587 * request_queue and elevator_type pair.
3588 * It is just used by __blk_mq_update_nr_hw_queues to cache
3589 * the elevator_type associated with a request_queue.
3591 struct blk_mq_qe_pair
{
3592 struct list_head node
;
3593 struct request_queue
*q
;
3594 struct elevator_type
*type
;
3598 * Cache the elevator_type in qe pair list and switch the
3599 * io scheduler to 'none'
3601 static bool blk_mq_elv_switch_none(struct list_head
*head
,
3602 struct request_queue
*q
)
3604 struct blk_mq_qe_pair
*qe
;
3609 qe
= kmalloc(sizeof(*qe
), GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
);
3613 INIT_LIST_HEAD(&qe
->node
);
3615 qe
->type
= q
->elevator
->type
;
3616 list_add(&qe
->node
, head
);
3618 mutex_lock(&q
->sysfs_lock
);
3620 * After elevator_switch_mq, the previous elevator_queue will be
3621 * released by elevator_release. The reference of the io scheduler
3622 * module get by elevator_get will also be put. So we need to get
3623 * a reference of the io scheduler module here to prevent it to be
3626 __module_get(qe
->type
->elevator_owner
);
3627 elevator_switch_mq(q
, NULL
);
3628 mutex_unlock(&q
->sysfs_lock
);
3633 static void blk_mq_elv_switch_back(struct list_head
*head
,
3634 struct request_queue
*q
)
3636 struct blk_mq_qe_pair
*qe
;
3637 struct elevator_type
*t
= NULL
;
3639 list_for_each_entry(qe
, head
, node
)
3648 list_del(&qe
->node
);
3651 mutex_lock(&q
->sysfs_lock
);
3652 elevator_switch_mq(q
, t
);
3653 mutex_unlock(&q
->sysfs_lock
);
3656 static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
,
3659 struct request_queue
*q
;
3661 int prev_nr_hw_queues
;
3663 lockdep_assert_held(&set
->tag_list_lock
);
3665 if (set
->nr_maps
== 1 && nr_hw_queues
> nr_cpu_ids
)
3666 nr_hw_queues
= nr_cpu_ids
;
3667 if (nr_hw_queues
< 1)
3669 if (set
->nr_maps
== 1 && nr_hw_queues
== set
->nr_hw_queues
)
3672 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
3673 blk_mq_freeze_queue(q
);
3675 * Switch IO scheduler to 'none', cleaning up the data associated
3676 * with the previous scheduler. We will switch back once we are done
3677 * updating the new sw to hw queue mappings.
3679 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
3680 if (!blk_mq_elv_switch_none(&head
, q
))
3683 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
3684 blk_mq_debugfs_unregister_hctxs(q
);
3685 blk_mq_sysfs_unregister(q
);
3688 prev_nr_hw_queues
= set
->nr_hw_queues
;
3689 if (blk_mq_realloc_tag_set_tags(set
, set
->nr_hw_queues
, nr_hw_queues
) <
3693 set
->nr_hw_queues
= nr_hw_queues
;
3695 blk_mq_update_queue_map(set
);
3696 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
3697 blk_mq_realloc_hw_ctxs(set
, q
);
3698 if (q
->nr_hw_queues
!= set
->nr_hw_queues
) {
3699 pr_warn("Increasing nr_hw_queues to %d fails, fallback to %d\n",
3700 nr_hw_queues
, prev_nr_hw_queues
);
3701 set
->nr_hw_queues
= prev_nr_hw_queues
;
3702 blk_mq_map_queues(&set
->map
[HCTX_TYPE_DEFAULT
]);
3705 blk_mq_map_swqueue(q
);
3709 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
3710 blk_mq_sysfs_register(q
);
3711 blk_mq_debugfs_register_hctxs(q
);
3715 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
3716 blk_mq_elv_switch_back(&head
, q
);
3718 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
3719 blk_mq_unfreeze_queue(q
);
3722 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
, int nr_hw_queues
)
3724 mutex_lock(&set
->tag_list_lock
);
3725 __blk_mq_update_nr_hw_queues(set
, nr_hw_queues
);
3726 mutex_unlock(&set
->tag_list_lock
);
3728 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues
);
3730 /* Enable polling stats and return whether they were already enabled. */
3731 static bool blk_poll_stats_enable(struct request_queue
*q
)
3733 if (test_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
) ||
3734 blk_queue_flag_test_and_set(QUEUE_FLAG_POLL_STATS
, q
))
3736 blk_stat_add_callback(q
, q
->poll_cb
);
3740 static void blk_mq_poll_stats_start(struct request_queue
*q
)
3743 * We don't arm the callback if polling stats are not enabled or the
3744 * callback is already active.
3746 if (!test_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
) ||
3747 blk_stat_is_active(q
->poll_cb
))
3750 blk_stat_activate_msecs(q
->poll_cb
, 100);
3753 static void blk_mq_poll_stats_fn(struct blk_stat_callback
*cb
)
3755 struct request_queue
*q
= cb
->data
;
3758 for (bucket
= 0; bucket
< BLK_MQ_POLL_STATS_BKTS
; bucket
++) {
3759 if (cb
->stat
[bucket
].nr_samples
)
3760 q
->poll_stat
[bucket
] = cb
->stat
[bucket
];
3764 static unsigned long blk_mq_poll_nsecs(struct request_queue
*q
,
3767 unsigned long ret
= 0;
3771 * If stats collection isn't on, don't sleep but turn it on for
3774 if (!blk_poll_stats_enable(q
))
3778 * As an optimistic guess, use half of the mean service time
3779 * for this type of request. We can (and should) make this smarter.
3780 * For instance, if the completion latencies are tight, we can
3781 * get closer than just half the mean. This is especially
3782 * important on devices where the completion latencies are longer
3783 * than ~10 usec. We do use the stats for the relevant IO size
3784 * if available which does lead to better estimates.
3786 bucket
= blk_mq_poll_stats_bkt(rq
);
3790 if (q
->poll_stat
[bucket
].nr_samples
)
3791 ret
= (q
->poll_stat
[bucket
].mean
+ 1) / 2;
3796 static bool blk_mq_poll_hybrid_sleep(struct request_queue
*q
,
3799 struct hrtimer_sleeper hs
;
3800 enum hrtimer_mode mode
;
3804 if (rq
->rq_flags
& RQF_MQ_POLL_SLEPT
)
3808 * If we get here, hybrid polling is enabled. Hence poll_nsec can be:
3810 * 0: use half of prev avg
3811 * >0: use this specific value
3813 if (q
->poll_nsec
> 0)
3814 nsecs
= q
->poll_nsec
;
3816 nsecs
= blk_mq_poll_nsecs(q
, rq
);
3821 rq
->rq_flags
|= RQF_MQ_POLL_SLEPT
;
3824 * This will be replaced with the stats tracking code, using
3825 * 'avg_completion_time / 2' as the pre-sleep target.
3829 mode
= HRTIMER_MODE_REL
;
3830 hrtimer_init_sleeper_on_stack(&hs
, CLOCK_MONOTONIC
, mode
);
3831 hrtimer_set_expires(&hs
.timer
, kt
);
3834 if (blk_mq_rq_state(rq
) == MQ_RQ_COMPLETE
)
3836 set_current_state(TASK_UNINTERRUPTIBLE
);
3837 hrtimer_sleeper_start_expires(&hs
, mode
);
3840 hrtimer_cancel(&hs
.timer
);
3841 mode
= HRTIMER_MODE_ABS
;
3842 } while (hs
.task
&& !signal_pending(current
));
3844 __set_current_state(TASK_RUNNING
);
3845 destroy_hrtimer_on_stack(&hs
.timer
);
3849 static bool blk_mq_poll_hybrid(struct request_queue
*q
,
3850 struct blk_mq_hw_ctx
*hctx
, blk_qc_t cookie
)
3854 if (q
->poll_nsec
== BLK_MQ_POLL_CLASSIC
)
3857 if (!blk_qc_t_is_internal(cookie
))
3858 rq
= blk_mq_tag_to_rq(hctx
->tags
, blk_qc_t_to_tag(cookie
));
3860 rq
= blk_mq_tag_to_rq(hctx
->sched_tags
, blk_qc_t_to_tag(cookie
));
3862 * With scheduling, if the request has completed, we'll
3863 * get a NULL return here, as we clear the sched tag when
3864 * that happens. The request still remains valid, like always,
3865 * so we should be safe with just the NULL check.
3871 return blk_mq_poll_hybrid_sleep(q
, rq
);
3875 * blk_poll - poll for IO completions
3877 * @cookie: cookie passed back at IO submission time
3878 * @spin: whether to spin for completions
3881 * Poll for completions on the passed in queue. Returns number of
3882 * completed entries found. If @spin is true, then blk_poll will continue
3883 * looping until at least one completion is found, unless the task is
3884 * otherwise marked running (or we need to reschedule).
3886 int blk_poll(struct request_queue
*q
, blk_qc_t cookie
, bool spin
)
3888 struct blk_mq_hw_ctx
*hctx
;
3891 if (!blk_qc_t_valid(cookie
) ||
3892 !test_bit(QUEUE_FLAG_POLL
, &q
->queue_flags
))
3896 blk_flush_plug_list(current
->plug
, false);
3898 hctx
= q
->queue_hw_ctx
[blk_qc_t_to_queue_num(cookie
)];
3901 * If we sleep, have the caller restart the poll loop to reset
3902 * the state. Like for the other success return cases, the
3903 * caller is responsible for checking if the IO completed. If
3904 * the IO isn't complete, we'll get called again and will go
3905 * straight to the busy poll loop. If specified not to spin,
3906 * we also should not sleep.
3908 if (spin
&& blk_mq_poll_hybrid(q
, hctx
, cookie
))
3911 hctx
->poll_considered
++;
3913 state
= current
->state
;
3917 hctx
->poll_invoked
++;
3919 ret
= q
->mq_ops
->poll(hctx
);
3921 hctx
->poll_success
++;
3922 __set_current_state(TASK_RUNNING
);
3926 if (signal_pending_state(state
, current
))
3927 __set_current_state(TASK_RUNNING
);
3929 if (current
->state
== TASK_RUNNING
)
3931 if (ret
< 0 || !spin
)
3934 } while (!need_resched());
3936 __set_current_state(TASK_RUNNING
);
3939 EXPORT_SYMBOL_GPL(blk_poll
);
3941 unsigned int blk_mq_rq_cpu(struct request
*rq
)
3943 return rq
->mq_ctx
->cpu
;
3945 EXPORT_SYMBOL(blk_mq_rq_cpu
);
3947 static int __init
blk_mq_init(void)
3951 for_each_possible_cpu(i
)
3952 init_llist_head(&per_cpu(blk_cpu_done
, i
));
3953 open_softirq(BLOCK_SOFTIRQ
, blk_done_softirq
);
3955 cpuhp_setup_state_nocalls(CPUHP_BLOCK_SOFTIRQ_DEAD
,
3956 "block/softirq:dead", NULL
,
3957 blk_softirq_cpu_dead
);
3958 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD
, "block/mq:dead", NULL
,
3959 blk_mq_hctx_notify_dead
);
3960 cpuhp_setup_state_multi(CPUHP_AP_BLK_MQ_ONLINE
, "block/mq:online",
3961 blk_mq_hctx_notify_online
,
3962 blk_mq_hctx_notify_offline
);
3965 subsys_initcall(blk_mq_init
);