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
, bool force_atomic
)
193 mutex_lock(&q
->mq_freeze_lock
);
195 q
->q_usage_counter
.data
->force_atomic
= true;
196 q
->mq_freeze_depth
--;
197 WARN_ON_ONCE(q
->mq_freeze_depth
< 0);
198 if (!q
->mq_freeze_depth
) {
199 percpu_ref_resurrect(&q
->q_usage_counter
);
200 wake_up_all(&q
->mq_freeze_wq
);
202 mutex_unlock(&q
->mq_freeze_lock
);
205 void blk_mq_unfreeze_queue(struct request_queue
*q
)
207 __blk_mq_unfreeze_queue(q
, false);
209 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue
);
212 * FIXME: replace the scsi_internal_device_*block_nowait() calls in the
213 * mpt3sas driver such that this function can be removed.
215 void blk_mq_quiesce_queue_nowait(struct request_queue
*q
)
217 blk_queue_flag_set(QUEUE_FLAG_QUIESCED
, q
);
219 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait
);
222 * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished
225 * Note: this function does not prevent that the struct request end_io()
226 * callback function is invoked. Once this function is returned, we make
227 * sure no dispatch can happen until the queue is unquiesced via
228 * blk_mq_unquiesce_queue().
230 void blk_mq_quiesce_queue(struct request_queue
*q
)
232 struct blk_mq_hw_ctx
*hctx
;
236 blk_mq_quiesce_queue_nowait(q
);
238 queue_for_each_hw_ctx(q
, hctx
, i
) {
239 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
240 synchronize_srcu(hctx
->srcu
);
247 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue
);
250 * blk_mq_unquiesce_queue() - counterpart of blk_mq_quiesce_queue()
253 * This function recovers queue into the state before quiescing
254 * which is done by blk_mq_quiesce_queue.
256 void blk_mq_unquiesce_queue(struct request_queue
*q
)
258 blk_queue_flag_clear(QUEUE_FLAG_QUIESCED
, q
);
260 /* dispatch requests which are inserted during quiescing */
261 blk_mq_run_hw_queues(q
, true);
263 EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue
);
265 void blk_mq_wake_waiters(struct request_queue
*q
)
267 struct blk_mq_hw_ctx
*hctx
;
270 queue_for_each_hw_ctx(q
, hctx
, i
)
271 if (blk_mq_hw_queue_mapped(hctx
))
272 blk_mq_tag_wakeup_all(hctx
->tags
, true);
276 * Only need start/end time stamping if we have iostat or
277 * blk stats enabled, or using an IO scheduler.
279 static inline bool blk_mq_need_time_stamp(struct request
*rq
)
281 return (rq
->rq_flags
& (RQF_IO_STAT
| RQF_STATS
)) || rq
->q
->elevator
;
284 static struct request
*blk_mq_rq_ctx_init(struct blk_mq_alloc_data
*data
,
285 unsigned int tag
, u64 alloc_time_ns
)
287 struct blk_mq_tags
*tags
= blk_mq_tags_from_data(data
);
288 struct request
*rq
= tags
->static_rqs
[tag
];
290 if (data
->q
->elevator
) {
291 rq
->tag
= BLK_MQ_NO_TAG
;
292 rq
->internal_tag
= tag
;
295 rq
->internal_tag
= BLK_MQ_NO_TAG
;
298 /* csd/requeue_work/fifo_time is initialized before use */
300 rq
->mq_ctx
= data
->ctx
;
301 rq
->mq_hctx
= data
->hctx
;
303 rq
->cmd_flags
= data
->cmd_flags
;
304 if (data
->flags
& BLK_MQ_REQ_PM
)
305 rq
->rq_flags
|= RQF_PM
;
306 if (blk_queue_io_stat(data
->q
))
307 rq
->rq_flags
|= RQF_IO_STAT
;
308 INIT_LIST_HEAD(&rq
->queuelist
);
309 INIT_HLIST_NODE(&rq
->hash
);
310 RB_CLEAR_NODE(&rq
->rb_node
);
313 #ifdef CONFIG_BLK_RQ_ALLOC_TIME
314 rq
->alloc_time_ns
= alloc_time_ns
;
316 if (blk_mq_need_time_stamp(rq
))
317 rq
->start_time_ns
= ktime_get_ns();
319 rq
->start_time_ns
= 0;
320 rq
->io_start_time_ns
= 0;
321 rq
->stats_sectors
= 0;
322 rq
->nr_phys_segments
= 0;
323 #if defined(CONFIG_BLK_DEV_INTEGRITY)
324 rq
->nr_integrity_segments
= 0;
326 blk_crypto_rq_set_defaults(rq
);
327 /* tag was already set */
328 WRITE_ONCE(rq
->deadline
, 0);
333 rq
->end_io_data
= NULL
;
335 data
->ctx
->rq_dispatched
[op_is_sync(data
->cmd_flags
)]++;
336 refcount_set(&rq
->ref
, 1);
338 if (!op_is_flush(data
->cmd_flags
)) {
339 struct elevator_queue
*e
= data
->q
->elevator
;
342 if (e
&& e
->type
->ops
.prepare_request
) {
343 if (e
->type
->icq_cache
)
344 blk_mq_sched_assign_ioc(rq
);
346 e
->type
->ops
.prepare_request(rq
);
347 rq
->rq_flags
|= RQF_ELVPRIV
;
351 data
->hctx
->queued
++;
355 static struct request
*__blk_mq_alloc_request(struct blk_mq_alloc_data
*data
)
357 struct request_queue
*q
= data
->q
;
358 struct elevator_queue
*e
= q
->elevator
;
359 u64 alloc_time_ns
= 0;
362 /* alloc_time includes depth and tag waits */
363 if (blk_queue_rq_alloc_time(q
))
364 alloc_time_ns
= ktime_get_ns();
366 if (data
->cmd_flags
& REQ_NOWAIT
)
367 data
->flags
|= BLK_MQ_REQ_NOWAIT
;
371 * Flush/passthrough requests are special and go directly to the
372 * dispatch list. Don't include reserved tags in the
373 * limiting, as it isn't useful.
375 if (!op_is_flush(data
->cmd_flags
) &&
376 !blk_op_is_passthrough(data
->cmd_flags
) &&
377 e
->type
->ops
.limit_depth
&&
378 !(data
->flags
& BLK_MQ_REQ_RESERVED
))
379 e
->type
->ops
.limit_depth(data
->cmd_flags
, data
);
383 data
->ctx
= blk_mq_get_ctx(q
);
384 data
->hctx
= blk_mq_map_queue(q
, data
->cmd_flags
, data
->ctx
);
386 blk_mq_tag_busy(data
->hctx
);
389 * Waiting allocations only fail because of an inactive hctx. In that
390 * case just retry the hctx assignment and tag allocation as CPU hotplug
391 * should have migrated us to an online CPU by now.
393 tag
= blk_mq_get_tag(data
);
394 if (tag
== BLK_MQ_NO_TAG
) {
395 if (data
->flags
& BLK_MQ_REQ_NOWAIT
)
399 * Give up the CPU and sleep for a random short time to ensure
400 * that thread using a realtime scheduling class are migrated
401 * off the CPU, and thus off the hctx that is going away.
406 return blk_mq_rq_ctx_init(data
, tag
, alloc_time_ns
);
409 struct request
*blk_mq_alloc_request(struct request_queue
*q
, unsigned int op
,
410 blk_mq_req_flags_t flags
)
412 struct blk_mq_alloc_data data
= {
420 ret
= blk_queue_enter(q
, flags
);
424 rq
= __blk_mq_alloc_request(&data
);
428 rq
->__sector
= (sector_t
) -1;
429 rq
->bio
= rq
->biotail
= NULL
;
433 return ERR_PTR(-EWOULDBLOCK
);
435 EXPORT_SYMBOL(blk_mq_alloc_request
);
437 struct request
*blk_mq_alloc_request_hctx(struct request_queue
*q
,
438 unsigned int op
, blk_mq_req_flags_t flags
, unsigned int hctx_idx
)
440 struct blk_mq_alloc_data data
= {
445 u64 alloc_time_ns
= 0;
450 /* alloc_time includes depth and tag waits */
451 if (blk_queue_rq_alloc_time(q
))
452 alloc_time_ns
= ktime_get_ns();
455 * If the tag allocator sleeps we could get an allocation for a
456 * different hardware context. No need to complicate the low level
457 * allocator for this for the rare use case of a command tied to
460 if (WARN_ON_ONCE(!(flags
& (BLK_MQ_REQ_NOWAIT
| BLK_MQ_REQ_RESERVED
))))
461 return ERR_PTR(-EINVAL
);
463 if (hctx_idx
>= q
->nr_hw_queues
)
464 return ERR_PTR(-EIO
);
466 ret
= blk_queue_enter(q
, flags
);
471 * Check if the hardware context is actually mapped to anything.
472 * If not tell the caller that it should skip this queue.
475 data
.hctx
= q
->queue_hw_ctx
[hctx_idx
];
476 if (!blk_mq_hw_queue_mapped(data
.hctx
))
478 cpu
= cpumask_first_and(data
.hctx
->cpumask
, cpu_online_mask
);
479 if (cpu
>= nr_cpu_ids
)
481 data
.ctx
= __blk_mq_get_ctx(q
, cpu
);
484 blk_mq_tag_busy(data
.hctx
);
487 tag
= blk_mq_get_tag(&data
);
488 if (tag
== BLK_MQ_NO_TAG
)
490 return blk_mq_rq_ctx_init(&data
, tag
, alloc_time_ns
);
496 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx
);
498 static void __blk_mq_free_request(struct request
*rq
)
500 struct request_queue
*q
= rq
->q
;
501 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
502 struct blk_mq_hw_ctx
*hctx
= rq
->mq_hctx
;
503 const int sched_tag
= rq
->internal_tag
;
505 blk_crypto_free_request(rq
);
506 blk_pm_mark_last_busy(rq
);
508 if (rq
->tag
!= BLK_MQ_NO_TAG
)
509 blk_mq_put_tag(hctx
->tags
, ctx
, rq
->tag
);
510 if (sched_tag
!= BLK_MQ_NO_TAG
)
511 blk_mq_put_tag(hctx
->sched_tags
, ctx
, sched_tag
);
512 blk_mq_sched_restart(hctx
);
516 void blk_mq_free_request(struct request
*rq
)
518 struct request_queue
*q
= rq
->q
;
519 struct elevator_queue
*e
= q
->elevator
;
520 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
521 struct blk_mq_hw_ctx
*hctx
= rq
->mq_hctx
;
523 if (rq
->rq_flags
& RQF_ELVPRIV
) {
524 if (e
&& e
->type
->ops
.finish_request
)
525 e
->type
->ops
.finish_request(rq
);
527 put_io_context(rq
->elv
.icq
->ioc
);
532 ctx
->rq_completed
[rq_is_sync(rq
)]++;
533 if (rq
->rq_flags
& RQF_MQ_INFLIGHT
)
534 __blk_mq_dec_active_requests(hctx
);
536 if (unlikely(laptop_mode
&& !blk_rq_is_passthrough(rq
)))
537 laptop_io_completion(q
->disk
->bdi
);
541 WRITE_ONCE(rq
->state
, MQ_RQ_IDLE
);
542 if (refcount_dec_and_test(&rq
->ref
))
543 __blk_mq_free_request(rq
);
545 EXPORT_SYMBOL_GPL(blk_mq_free_request
);
547 inline void __blk_mq_end_request(struct request
*rq
, blk_status_t error
)
551 if (blk_mq_need_time_stamp(rq
))
552 now
= ktime_get_ns();
554 if (rq
->rq_flags
& RQF_STATS
) {
555 blk_mq_poll_stats_start(rq
->q
);
556 blk_stat_add(rq
, now
);
559 blk_mq_sched_completed_request(rq
, now
);
561 blk_account_io_done(rq
, now
);
564 rq_qos_done(rq
->q
, rq
);
565 rq
->end_io(rq
, error
);
567 blk_mq_free_request(rq
);
570 EXPORT_SYMBOL(__blk_mq_end_request
);
572 void blk_mq_end_request(struct request
*rq
, blk_status_t error
)
574 if (blk_update_request(rq
, error
, blk_rq_bytes(rq
)))
576 __blk_mq_end_request(rq
, error
);
578 EXPORT_SYMBOL(blk_mq_end_request
);
580 static void blk_complete_reqs(struct llist_head
*list
)
582 struct llist_node
*entry
= llist_reverse_order(llist_del_all(list
));
583 struct request
*rq
, *next
;
585 llist_for_each_entry_safe(rq
, next
, entry
, ipi_list
)
586 rq
->q
->mq_ops
->complete(rq
);
589 static __latent_entropy
void blk_done_softirq(struct softirq_action
*h
)
591 blk_complete_reqs(this_cpu_ptr(&blk_cpu_done
));
594 static int blk_softirq_cpu_dead(unsigned int cpu
)
596 blk_complete_reqs(&per_cpu(blk_cpu_done
, cpu
));
600 static void __blk_mq_complete_request_remote(void *data
)
602 __raise_softirq_irqoff(BLOCK_SOFTIRQ
);
605 static inline bool blk_mq_complete_need_ipi(struct request
*rq
)
607 int cpu
= raw_smp_processor_id();
609 if (!IS_ENABLED(CONFIG_SMP
) ||
610 !test_bit(QUEUE_FLAG_SAME_COMP
, &rq
->q
->queue_flags
))
613 * With force threaded interrupts enabled, raising softirq from an SMP
614 * function call will always result in waking the ksoftirqd thread.
615 * This is probably worse than completing the request on a different
618 if (force_irqthreads())
621 /* same CPU or cache domain? Complete locally */
622 if (cpu
== rq
->mq_ctx
->cpu
||
623 (!test_bit(QUEUE_FLAG_SAME_FORCE
, &rq
->q
->queue_flags
) &&
624 cpus_share_cache(cpu
, rq
->mq_ctx
->cpu
)))
627 /* don't try to IPI to an offline CPU */
628 return cpu_online(rq
->mq_ctx
->cpu
);
631 static void blk_mq_complete_send_ipi(struct request
*rq
)
633 struct llist_head
*list
;
636 cpu
= rq
->mq_ctx
->cpu
;
637 list
= &per_cpu(blk_cpu_done
, cpu
);
638 if (llist_add(&rq
->ipi_list
, list
)) {
639 INIT_CSD(&rq
->csd
, __blk_mq_complete_request_remote
, rq
);
640 smp_call_function_single_async(cpu
, &rq
->csd
);
644 static void blk_mq_raise_softirq(struct request
*rq
)
646 struct llist_head
*list
;
649 list
= this_cpu_ptr(&blk_cpu_done
);
650 if (llist_add(&rq
->ipi_list
, list
))
651 raise_softirq(BLOCK_SOFTIRQ
);
655 bool blk_mq_complete_request_remote(struct request
*rq
)
657 WRITE_ONCE(rq
->state
, MQ_RQ_COMPLETE
);
660 * For a polled request, always complete locallly, it's pointless
661 * to redirect the completion.
663 if (rq
->cmd_flags
& REQ_HIPRI
)
666 if (blk_mq_complete_need_ipi(rq
)) {
667 blk_mq_complete_send_ipi(rq
);
671 if (rq
->q
->nr_hw_queues
== 1) {
672 blk_mq_raise_softirq(rq
);
677 EXPORT_SYMBOL_GPL(blk_mq_complete_request_remote
);
680 * blk_mq_complete_request - end I/O on a request
681 * @rq: the request being processed
684 * Complete a request by scheduling the ->complete_rq operation.
686 void blk_mq_complete_request(struct request
*rq
)
688 if (!blk_mq_complete_request_remote(rq
))
689 rq
->q
->mq_ops
->complete(rq
);
691 EXPORT_SYMBOL(blk_mq_complete_request
);
693 static void hctx_unlock(struct blk_mq_hw_ctx
*hctx
, int srcu_idx
)
694 __releases(hctx
->srcu
)
696 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
))
699 srcu_read_unlock(hctx
->srcu
, srcu_idx
);
702 static void hctx_lock(struct blk_mq_hw_ctx
*hctx
, int *srcu_idx
)
703 __acquires(hctx
->srcu
)
705 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
706 /* shut up gcc false positive */
710 *srcu_idx
= srcu_read_lock(hctx
->srcu
);
714 * blk_mq_start_request - Start processing a request
715 * @rq: Pointer to request to be started
717 * Function used by device drivers to notify the block layer that a request
718 * is going to be processed now, so blk layer can do proper initializations
719 * such as starting the timeout timer.
721 void blk_mq_start_request(struct request
*rq
)
723 struct request_queue
*q
= rq
->q
;
725 trace_block_rq_issue(rq
);
727 if (test_bit(QUEUE_FLAG_STATS
, &q
->queue_flags
)) {
728 rq
->io_start_time_ns
= ktime_get_ns();
729 rq
->stats_sectors
= blk_rq_sectors(rq
);
730 rq
->rq_flags
|= RQF_STATS
;
734 WARN_ON_ONCE(blk_mq_rq_state(rq
) != MQ_RQ_IDLE
);
737 WRITE_ONCE(rq
->state
, MQ_RQ_IN_FLIGHT
);
739 #ifdef CONFIG_BLK_DEV_INTEGRITY
740 if (blk_integrity_rq(rq
) && req_op(rq
) == REQ_OP_WRITE
)
741 q
->integrity
.profile
->prepare_fn(rq
);
744 EXPORT_SYMBOL(blk_mq_start_request
);
746 static void __blk_mq_requeue_request(struct request
*rq
)
748 struct request_queue
*q
= rq
->q
;
750 blk_mq_put_driver_tag(rq
);
752 trace_block_rq_requeue(rq
);
753 rq_qos_requeue(q
, rq
);
755 if (blk_mq_request_started(rq
)) {
756 WRITE_ONCE(rq
->state
, MQ_RQ_IDLE
);
757 rq
->rq_flags
&= ~RQF_TIMED_OUT
;
761 void blk_mq_requeue_request(struct request
*rq
, bool kick_requeue_list
)
763 __blk_mq_requeue_request(rq
);
765 /* this request will be re-inserted to io scheduler queue */
766 blk_mq_sched_requeue_request(rq
);
768 blk_mq_add_to_requeue_list(rq
, true, kick_requeue_list
);
770 EXPORT_SYMBOL(blk_mq_requeue_request
);
772 static void blk_mq_requeue_work(struct work_struct
*work
)
774 struct request_queue
*q
=
775 container_of(work
, struct request_queue
, requeue_work
.work
);
777 struct request
*rq
, *next
;
779 spin_lock_irq(&q
->requeue_lock
);
780 list_splice_init(&q
->requeue_list
, &rq_list
);
781 spin_unlock_irq(&q
->requeue_lock
);
783 list_for_each_entry_safe(rq
, next
, &rq_list
, queuelist
) {
784 if (!(rq
->rq_flags
& (RQF_SOFTBARRIER
| RQF_DONTPREP
)))
787 rq
->rq_flags
&= ~RQF_SOFTBARRIER
;
788 list_del_init(&rq
->queuelist
);
790 * If RQF_DONTPREP, rq has contained some driver specific
791 * data, so insert it to hctx dispatch list to avoid any
794 if (rq
->rq_flags
& RQF_DONTPREP
)
795 blk_mq_request_bypass_insert(rq
, false, false);
797 blk_mq_sched_insert_request(rq
, true, false, false);
800 while (!list_empty(&rq_list
)) {
801 rq
= list_entry(rq_list
.next
, struct request
, queuelist
);
802 list_del_init(&rq
->queuelist
);
803 blk_mq_sched_insert_request(rq
, false, false, false);
806 blk_mq_run_hw_queues(q
, false);
809 void blk_mq_add_to_requeue_list(struct request
*rq
, bool at_head
,
810 bool kick_requeue_list
)
812 struct request_queue
*q
= rq
->q
;
816 * We abuse this flag that is otherwise used by the I/O scheduler to
817 * request head insertion from the workqueue.
819 BUG_ON(rq
->rq_flags
& RQF_SOFTBARRIER
);
821 spin_lock_irqsave(&q
->requeue_lock
, flags
);
823 rq
->rq_flags
|= RQF_SOFTBARRIER
;
824 list_add(&rq
->queuelist
, &q
->requeue_list
);
826 list_add_tail(&rq
->queuelist
, &q
->requeue_list
);
828 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
830 if (kick_requeue_list
)
831 blk_mq_kick_requeue_list(q
);
834 void blk_mq_kick_requeue_list(struct request_queue
*q
)
836 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND
, &q
->requeue_work
, 0);
838 EXPORT_SYMBOL(blk_mq_kick_requeue_list
);
840 void blk_mq_delay_kick_requeue_list(struct request_queue
*q
,
843 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND
, &q
->requeue_work
,
844 msecs_to_jiffies(msecs
));
846 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list
);
848 struct request
*blk_mq_tag_to_rq(struct blk_mq_tags
*tags
, unsigned int tag
)
850 if (tag
< tags
->nr_tags
) {
851 prefetch(tags
->rqs
[tag
]);
852 return tags
->rqs
[tag
];
857 EXPORT_SYMBOL(blk_mq_tag_to_rq
);
859 static bool blk_mq_rq_inflight(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
,
860 void *priv
, bool reserved
)
863 * If we find a request that isn't idle and the queue matches,
864 * we know the queue is busy. Return false to stop the iteration.
866 if (blk_mq_request_started(rq
) && rq
->q
== hctx
->queue
) {
876 bool blk_mq_queue_inflight(struct request_queue
*q
)
880 blk_mq_queue_tag_busy_iter(q
, blk_mq_rq_inflight
, &busy
);
883 EXPORT_SYMBOL_GPL(blk_mq_queue_inflight
);
885 static void blk_mq_rq_timed_out(struct request
*req
, bool reserved
)
887 req
->rq_flags
|= RQF_TIMED_OUT
;
888 if (req
->q
->mq_ops
->timeout
) {
889 enum blk_eh_timer_return ret
;
891 ret
= req
->q
->mq_ops
->timeout(req
, reserved
);
892 if (ret
== BLK_EH_DONE
)
894 WARN_ON_ONCE(ret
!= BLK_EH_RESET_TIMER
);
900 static bool blk_mq_req_expired(struct request
*rq
, unsigned long *next
)
902 unsigned long deadline
;
904 if (blk_mq_rq_state(rq
) != MQ_RQ_IN_FLIGHT
)
906 if (rq
->rq_flags
& RQF_TIMED_OUT
)
909 deadline
= READ_ONCE(rq
->deadline
);
910 if (time_after_eq(jiffies
, deadline
))
915 else if (time_after(*next
, deadline
))
920 void blk_mq_put_rq_ref(struct request
*rq
)
924 else if (refcount_dec_and_test(&rq
->ref
))
925 __blk_mq_free_request(rq
);
928 static bool blk_mq_check_expired(struct blk_mq_hw_ctx
*hctx
,
929 struct request
*rq
, void *priv
, bool reserved
)
931 unsigned long *next
= priv
;
934 * blk_mq_queue_tag_busy_iter() has locked the request, so it cannot
935 * be reallocated underneath the timeout handler's processing, then
936 * the expire check is reliable. If the request is not expired, then
937 * it was completed and reallocated as a new request after returning
938 * from blk_mq_check_expired().
940 if (blk_mq_req_expired(rq
, next
))
941 blk_mq_rq_timed_out(rq
, reserved
);
945 static void blk_mq_timeout_work(struct work_struct
*work
)
947 struct request_queue
*q
=
948 container_of(work
, struct request_queue
, timeout_work
);
949 unsigned long next
= 0;
950 struct blk_mq_hw_ctx
*hctx
;
953 /* A deadlock might occur if a request is stuck requiring a
954 * timeout at the same time a queue freeze is waiting
955 * completion, since the timeout code would not be able to
956 * acquire the queue reference here.
958 * That's why we don't use blk_queue_enter here; instead, we use
959 * percpu_ref_tryget directly, because we need to be able to
960 * obtain a reference even in the short window between the queue
961 * starting to freeze, by dropping the first reference in
962 * blk_freeze_queue_start, and the moment the last request is
963 * consumed, marked by the instant q_usage_counter reaches
966 if (!percpu_ref_tryget(&q
->q_usage_counter
))
969 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_expired
, &next
);
972 mod_timer(&q
->timeout
, next
);
975 * Request timeouts are handled as a forward rolling timer. If
976 * we end up here it means that no requests are pending and
977 * also that no request has been pending for a while. Mark
980 queue_for_each_hw_ctx(q
, hctx
, i
) {
981 /* the hctx may be unmapped, so check it here */
982 if (blk_mq_hw_queue_mapped(hctx
))
983 blk_mq_tag_idle(hctx
);
989 struct flush_busy_ctx_data
{
990 struct blk_mq_hw_ctx
*hctx
;
991 struct list_head
*list
;
994 static bool flush_busy_ctx(struct sbitmap
*sb
, unsigned int bitnr
, void *data
)
996 struct flush_busy_ctx_data
*flush_data
= data
;
997 struct blk_mq_hw_ctx
*hctx
= flush_data
->hctx
;
998 struct blk_mq_ctx
*ctx
= hctx
->ctxs
[bitnr
];
999 enum hctx_type type
= hctx
->type
;
1001 spin_lock(&ctx
->lock
);
1002 list_splice_tail_init(&ctx
->rq_lists
[type
], flush_data
->list
);
1003 sbitmap_clear_bit(sb
, bitnr
);
1004 spin_unlock(&ctx
->lock
);
1009 * Process software queues that have been marked busy, splicing them
1010 * to the for-dispatch
1012 void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx
*hctx
, struct list_head
*list
)
1014 struct flush_busy_ctx_data data
= {
1019 sbitmap_for_each_set(&hctx
->ctx_map
, flush_busy_ctx
, &data
);
1021 EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs
);
1023 struct dispatch_rq_data
{
1024 struct blk_mq_hw_ctx
*hctx
;
1028 static bool dispatch_rq_from_ctx(struct sbitmap
*sb
, unsigned int bitnr
,
1031 struct dispatch_rq_data
*dispatch_data
= data
;
1032 struct blk_mq_hw_ctx
*hctx
= dispatch_data
->hctx
;
1033 struct blk_mq_ctx
*ctx
= hctx
->ctxs
[bitnr
];
1034 enum hctx_type type
= hctx
->type
;
1036 spin_lock(&ctx
->lock
);
1037 if (!list_empty(&ctx
->rq_lists
[type
])) {
1038 dispatch_data
->rq
= list_entry_rq(ctx
->rq_lists
[type
].next
);
1039 list_del_init(&dispatch_data
->rq
->queuelist
);
1040 if (list_empty(&ctx
->rq_lists
[type
]))
1041 sbitmap_clear_bit(sb
, bitnr
);
1043 spin_unlock(&ctx
->lock
);
1045 return !dispatch_data
->rq
;
1048 struct request
*blk_mq_dequeue_from_ctx(struct blk_mq_hw_ctx
*hctx
,
1049 struct blk_mq_ctx
*start
)
1051 unsigned off
= start
? start
->index_hw
[hctx
->type
] : 0;
1052 struct dispatch_rq_data data
= {
1057 __sbitmap_for_each_set(&hctx
->ctx_map
, off
,
1058 dispatch_rq_from_ctx
, &data
);
1063 static inline unsigned int queued_to_index(unsigned int queued
)
1068 return min(BLK_MQ_MAX_DISPATCH_ORDER
- 1, ilog2(queued
) + 1);
1071 static bool __blk_mq_get_driver_tag(struct request
*rq
)
1073 struct sbitmap_queue
*bt
= rq
->mq_hctx
->tags
->bitmap_tags
;
1074 unsigned int tag_offset
= rq
->mq_hctx
->tags
->nr_reserved_tags
;
1077 blk_mq_tag_busy(rq
->mq_hctx
);
1079 if (blk_mq_tag_is_reserved(rq
->mq_hctx
->sched_tags
, rq
->internal_tag
)) {
1080 bt
= rq
->mq_hctx
->tags
->breserved_tags
;
1083 if (!hctx_may_queue(rq
->mq_hctx
, bt
))
1087 tag
= __sbitmap_queue_get(bt
);
1088 if (tag
== BLK_MQ_NO_TAG
)
1091 rq
->tag
= tag
+ tag_offset
;
1095 bool blk_mq_get_driver_tag(struct request
*rq
)
1097 struct blk_mq_hw_ctx
*hctx
= rq
->mq_hctx
;
1099 if (rq
->tag
== BLK_MQ_NO_TAG
&& !__blk_mq_get_driver_tag(rq
))
1102 if ((hctx
->flags
& BLK_MQ_F_TAG_QUEUE_SHARED
) &&
1103 !(rq
->rq_flags
& RQF_MQ_INFLIGHT
)) {
1104 rq
->rq_flags
|= RQF_MQ_INFLIGHT
;
1105 __blk_mq_inc_active_requests(hctx
);
1107 hctx
->tags
->rqs
[rq
->tag
] = rq
;
1111 static int blk_mq_dispatch_wake(wait_queue_entry_t
*wait
, unsigned mode
,
1112 int flags
, void *key
)
1114 struct blk_mq_hw_ctx
*hctx
;
1116 hctx
= container_of(wait
, struct blk_mq_hw_ctx
, dispatch_wait
);
1118 spin_lock(&hctx
->dispatch_wait_lock
);
1119 if (!list_empty(&wait
->entry
)) {
1120 struct sbitmap_queue
*sbq
;
1122 list_del_init(&wait
->entry
);
1123 sbq
= hctx
->tags
->bitmap_tags
;
1124 atomic_dec(&sbq
->ws_active
);
1126 spin_unlock(&hctx
->dispatch_wait_lock
);
1128 blk_mq_run_hw_queue(hctx
, true);
1133 * Mark us waiting for a tag. For shared tags, this involves hooking us into
1134 * the tag wakeups. For non-shared tags, we can simply mark us needing a
1135 * restart. For both cases, take care to check the condition again after
1136 * marking us as waiting.
1138 static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx
*hctx
,
1141 struct sbitmap_queue
*sbq
= hctx
->tags
->bitmap_tags
;
1142 struct wait_queue_head
*wq
;
1143 wait_queue_entry_t
*wait
;
1146 if (!(hctx
->flags
& BLK_MQ_F_TAG_QUEUE_SHARED
)) {
1147 blk_mq_sched_mark_restart_hctx(hctx
);
1150 * It's possible that a tag was freed in the window between the
1151 * allocation failure and adding the hardware queue to the wait
1154 * Don't clear RESTART here, someone else could have set it.
1155 * At most this will cost an extra queue run.
1157 return blk_mq_get_driver_tag(rq
);
1160 wait
= &hctx
->dispatch_wait
;
1161 if (!list_empty_careful(&wait
->entry
))
1164 wq
= &bt_wait_ptr(sbq
, hctx
)->wait
;
1166 spin_lock_irq(&wq
->lock
);
1167 spin_lock(&hctx
->dispatch_wait_lock
);
1168 if (!list_empty(&wait
->entry
)) {
1169 spin_unlock(&hctx
->dispatch_wait_lock
);
1170 spin_unlock_irq(&wq
->lock
);
1174 atomic_inc(&sbq
->ws_active
);
1175 wait
->flags
&= ~WQ_FLAG_EXCLUSIVE
;
1176 __add_wait_queue(wq
, wait
);
1179 * It's possible that a tag was freed in the window between the
1180 * allocation failure and adding the hardware queue to the wait
1183 ret
= blk_mq_get_driver_tag(rq
);
1185 spin_unlock(&hctx
->dispatch_wait_lock
);
1186 spin_unlock_irq(&wq
->lock
);
1191 * We got a tag, remove ourselves from the wait queue to ensure
1192 * someone else gets the wakeup.
1194 list_del_init(&wait
->entry
);
1195 atomic_dec(&sbq
->ws_active
);
1196 spin_unlock(&hctx
->dispatch_wait_lock
);
1197 spin_unlock_irq(&wq
->lock
);
1202 #define BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT 8
1203 #define BLK_MQ_DISPATCH_BUSY_EWMA_FACTOR 4
1205 * Update dispatch busy with the Exponential Weighted Moving Average(EWMA):
1206 * - EWMA is one simple way to compute running average value
1207 * - weight(7/8 and 1/8) is applied so that it can decrease exponentially
1208 * - take 4 as factor for avoiding to get too small(0) result, and this
1209 * factor doesn't matter because EWMA decreases exponentially
1211 static void blk_mq_update_dispatch_busy(struct blk_mq_hw_ctx
*hctx
, bool busy
)
1215 ewma
= hctx
->dispatch_busy
;
1220 ewma
*= BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT
- 1;
1222 ewma
+= 1 << BLK_MQ_DISPATCH_BUSY_EWMA_FACTOR
;
1223 ewma
/= BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT
;
1225 hctx
->dispatch_busy
= ewma
;
1228 #define BLK_MQ_RESOURCE_DELAY 3 /* ms units */
1230 static void blk_mq_handle_dev_resource(struct request
*rq
,
1231 struct list_head
*list
)
1233 struct request
*next
=
1234 list_first_entry_or_null(list
, struct request
, queuelist
);
1237 * If an I/O scheduler has been configured and we got a driver tag for
1238 * the next request already, free it.
1241 blk_mq_put_driver_tag(next
);
1243 list_add(&rq
->queuelist
, list
);
1244 __blk_mq_requeue_request(rq
);
1247 static void blk_mq_handle_zone_resource(struct request
*rq
,
1248 struct list_head
*zone_list
)
1251 * If we end up here it is because we cannot dispatch a request to a
1252 * specific zone due to LLD level zone-write locking or other zone
1253 * related resource not being available. In this case, set the request
1254 * aside in zone_list for retrying it later.
1256 list_add(&rq
->queuelist
, zone_list
);
1257 __blk_mq_requeue_request(rq
);
1260 enum prep_dispatch
{
1262 PREP_DISPATCH_NO_TAG
,
1263 PREP_DISPATCH_NO_BUDGET
,
1266 static enum prep_dispatch
blk_mq_prep_dispatch_rq(struct request
*rq
,
1269 struct blk_mq_hw_ctx
*hctx
= rq
->mq_hctx
;
1270 int budget_token
= -1;
1273 budget_token
= blk_mq_get_dispatch_budget(rq
->q
);
1274 if (budget_token
< 0) {
1275 blk_mq_put_driver_tag(rq
);
1276 return PREP_DISPATCH_NO_BUDGET
;
1278 blk_mq_set_rq_budget_token(rq
, budget_token
);
1281 if (!blk_mq_get_driver_tag(rq
)) {
1283 * The initial allocation attempt failed, so we need to
1284 * rerun the hardware queue when a tag is freed. The
1285 * waitqueue takes care of that. If the queue is run
1286 * before we add this entry back on the dispatch list,
1287 * we'll re-run it below.
1289 if (!blk_mq_mark_tag_wait(hctx
, rq
)) {
1291 * All budgets not got from this function will be put
1292 * together during handling partial dispatch
1295 blk_mq_put_dispatch_budget(rq
->q
, budget_token
);
1296 return PREP_DISPATCH_NO_TAG
;
1300 return PREP_DISPATCH_OK
;
1303 /* release all allocated budgets before calling to blk_mq_dispatch_rq_list */
1304 static void blk_mq_release_budgets(struct request_queue
*q
,
1305 struct list_head
*list
)
1309 list_for_each_entry(rq
, list
, queuelist
) {
1310 int budget_token
= blk_mq_get_rq_budget_token(rq
);
1312 if (budget_token
>= 0)
1313 blk_mq_put_dispatch_budget(q
, budget_token
);
1318 * Returns true if we did some work AND can potentially do more.
1320 bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx
*hctx
, struct list_head
*list
,
1321 unsigned int nr_budgets
)
1323 enum prep_dispatch prep
;
1324 struct request_queue
*q
= hctx
->queue
;
1325 struct request
*rq
, *nxt
;
1327 blk_status_t ret
= BLK_STS_OK
;
1328 LIST_HEAD(zone_list
);
1329 bool needs_resource
= false;
1331 if (list_empty(list
))
1335 * Now process all the entries, sending them to the driver.
1337 errors
= queued
= 0;
1339 struct blk_mq_queue_data bd
;
1341 rq
= list_first_entry(list
, struct request
, queuelist
);
1343 WARN_ON_ONCE(hctx
!= rq
->mq_hctx
);
1344 prep
= blk_mq_prep_dispatch_rq(rq
, !nr_budgets
);
1345 if (prep
!= PREP_DISPATCH_OK
)
1348 list_del_init(&rq
->queuelist
);
1353 * Flag last if we have no more requests, or if we have more
1354 * but can't assign a driver tag to it.
1356 if (list_empty(list
))
1359 nxt
= list_first_entry(list
, struct request
, queuelist
);
1360 bd
.last
= !blk_mq_get_driver_tag(nxt
);
1364 * once the request is queued to lld, no need to cover the
1369 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1374 case BLK_STS_RESOURCE
:
1375 needs_resource
= true;
1377 case BLK_STS_DEV_RESOURCE
:
1378 blk_mq_handle_dev_resource(rq
, list
);
1380 case BLK_STS_ZONE_RESOURCE
:
1382 * Move the request to zone_list and keep going through
1383 * the dispatch list to find more requests the drive can
1386 blk_mq_handle_zone_resource(rq
, &zone_list
);
1387 needs_resource
= true;
1391 blk_mq_end_request(rq
, ret
);
1393 } while (!list_empty(list
));
1395 if (!list_empty(&zone_list
))
1396 list_splice_tail_init(&zone_list
, list
);
1398 hctx
->dispatched
[queued_to_index(queued
)]++;
1400 /* If we didn't flush the entire list, we could have told the driver
1401 * there was more coming, but that turned out to be a lie.
1403 if ((!list_empty(list
) || errors
) && q
->mq_ops
->commit_rqs
&& queued
)
1404 q
->mq_ops
->commit_rqs(hctx
);
1406 * Any items that need requeuing? Stuff them into hctx->dispatch,
1407 * that is where we will continue on next queue run.
1409 if (!list_empty(list
)) {
1411 /* For non-shared tags, the RESTART check will suffice */
1412 bool no_tag
= prep
== PREP_DISPATCH_NO_TAG
&&
1413 (hctx
->flags
& BLK_MQ_F_TAG_QUEUE_SHARED
);
1416 blk_mq_release_budgets(q
, list
);
1418 spin_lock(&hctx
->lock
);
1419 list_splice_tail_init(list
, &hctx
->dispatch
);
1420 spin_unlock(&hctx
->lock
);
1423 * Order adding requests to hctx->dispatch and checking
1424 * SCHED_RESTART flag. The pair of this smp_mb() is the one
1425 * in blk_mq_sched_restart(). Avoid restart code path to
1426 * miss the new added requests to hctx->dispatch, meantime
1427 * SCHED_RESTART is observed here.
1432 * If SCHED_RESTART was set by the caller of this function and
1433 * it is no longer set that means that it was cleared by another
1434 * thread and hence that a queue rerun is needed.
1436 * If 'no_tag' is set, that means that we failed getting
1437 * a driver tag with an I/O scheduler attached. If our dispatch
1438 * waitqueue is no longer active, ensure that we run the queue
1439 * AFTER adding our entries back to the list.
1441 * If no I/O scheduler has been configured it is possible that
1442 * the hardware queue got stopped and restarted before requests
1443 * were pushed back onto the dispatch list. Rerun the queue to
1444 * avoid starvation. Notes:
1445 * - blk_mq_run_hw_queue() checks whether or not a queue has
1446 * been stopped before rerunning a queue.
1447 * - Some but not all block drivers stop a queue before
1448 * returning BLK_STS_RESOURCE. Two exceptions are scsi-mq
1451 * If driver returns BLK_STS_RESOURCE and SCHED_RESTART
1452 * bit is set, run queue after a delay to avoid IO stalls
1453 * that could otherwise occur if the queue is idle. We'll do
1454 * similar if we couldn't get budget or couldn't lock a zone
1455 * and SCHED_RESTART is set.
1457 needs_restart
= blk_mq_sched_needs_restart(hctx
);
1458 if (prep
== PREP_DISPATCH_NO_BUDGET
)
1459 needs_resource
= true;
1460 if (!needs_restart
||
1461 (no_tag
&& list_empty_careful(&hctx
->dispatch_wait
.entry
)))
1462 blk_mq_run_hw_queue(hctx
, true);
1463 else if (needs_restart
&& needs_resource
)
1464 blk_mq_delay_run_hw_queue(hctx
, BLK_MQ_RESOURCE_DELAY
);
1466 blk_mq_update_dispatch_busy(hctx
, true);
1469 blk_mq_update_dispatch_busy(hctx
, false);
1471 return (queued
+ errors
) != 0;
1475 * __blk_mq_run_hw_queue - Run a hardware queue.
1476 * @hctx: Pointer to the hardware queue to run.
1478 * Send pending requests to the hardware.
1480 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1485 * We can't run the queue inline with ints disabled. Ensure that
1486 * we catch bad users of this early.
1488 WARN_ON_ONCE(in_interrupt());
1490 might_sleep_if(hctx
->flags
& BLK_MQ_F_BLOCKING
);
1492 hctx_lock(hctx
, &srcu_idx
);
1493 blk_mq_sched_dispatch_requests(hctx
);
1494 hctx_unlock(hctx
, srcu_idx
);
1497 static inline int blk_mq_first_mapped_cpu(struct blk_mq_hw_ctx
*hctx
)
1499 int cpu
= cpumask_first_and(hctx
->cpumask
, cpu_online_mask
);
1501 if (cpu
>= nr_cpu_ids
)
1502 cpu
= cpumask_first(hctx
->cpumask
);
1507 * It'd be great if the workqueue API had a way to pass
1508 * in a mask and had some smarts for more clever placement.
1509 * For now we just round-robin here, switching for every
1510 * BLK_MQ_CPU_WORK_BATCH queued items.
1512 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx
*hctx
)
1515 int next_cpu
= hctx
->next_cpu
;
1517 if (hctx
->queue
->nr_hw_queues
== 1)
1518 return WORK_CPU_UNBOUND
;
1520 if (--hctx
->next_cpu_batch
<= 0) {
1522 next_cpu
= cpumask_next_and(next_cpu
, hctx
->cpumask
,
1524 if (next_cpu
>= nr_cpu_ids
)
1525 next_cpu
= blk_mq_first_mapped_cpu(hctx
);
1526 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
1530 * Do unbound schedule if we can't find a online CPU for this hctx,
1531 * and it should only happen in the path of handling CPU DEAD.
1533 if (!cpu_online(next_cpu
)) {
1540 * Make sure to re-select CPU next time once after CPUs
1541 * in hctx->cpumask become online again.
1543 hctx
->next_cpu
= next_cpu
;
1544 hctx
->next_cpu_batch
= 1;
1545 return WORK_CPU_UNBOUND
;
1548 hctx
->next_cpu
= next_cpu
;
1553 * __blk_mq_delay_run_hw_queue - Run (or schedule to run) a hardware queue.
1554 * @hctx: Pointer to the hardware queue to run.
1555 * @async: If we want to run the queue asynchronously.
1556 * @msecs: Milliseconds of delay to wait before running the queue.
1558 * If !@async, try to run the queue now. Else, run the queue asynchronously and
1559 * with a delay of @msecs.
1561 static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
,
1562 unsigned long msecs
)
1564 if (unlikely(blk_mq_hctx_stopped(hctx
)))
1567 if (!async
&& !(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1568 int cpu
= get_cpu();
1569 if (cpumask_test_cpu(cpu
, hctx
->cpumask
)) {
1570 __blk_mq_run_hw_queue(hctx
);
1578 kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx
), &hctx
->run_work
,
1579 msecs_to_jiffies(msecs
));
1583 * blk_mq_delay_run_hw_queue - Run a hardware queue asynchronously.
1584 * @hctx: Pointer to the hardware queue to run.
1585 * @msecs: Milliseconds of delay to wait before running the queue.
1587 * Run a hardware queue asynchronously with a delay of @msecs.
1589 void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, unsigned long msecs
)
1591 __blk_mq_delay_run_hw_queue(hctx
, true, msecs
);
1593 EXPORT_SYMBOL(blk_mq_delay_run_hw_queue
);
1596 * blk_mq_run_hw_queue - Start to run a hardware queue.
1597 * @hctx: Pointer to the hardware queue to run.
1598 * @async: If we want to run the queue asynchronously.
1600 * Check if the request queue is not in a quiesced state and if there are
1601 * pending requests to be sent. If this is true, run the queue to send requests
1604 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1610 * When queue is quiesced, we may be switching io scheduler, or
1611 * updating nr_hw_queues, or other things, and we can't run queue
1612 * any more, even __blk_mq_hctx_has_pending() can't be called safely.
1614 * And queue will be rerun in blk_mq_unquiesce_queue() if it is
1617 hctx_lock(hctx
, &srcu_idx
);
1618 need_run
= !blk_queue_quiesced(hctx
->queue
) &&
1619 blk_mq_hctx_has_pending(hctx
);
1620 hctx_unlock(hctx
, srcu_idx
);
1623 __blk_mq_delay_run_hw_queue(hctx
, async
, 0);
1625 EXPORT_SYMBOL(blk_mq_run_hw_queue
);
1628 * Is the request queue handled by an IO scheduler that does not respect
1629 * hardware queues when dispatching?
1631 static bool blk_mq_has_sqsched(struct request_queue
*q
)
1633 struct elevator_queue
*e
= q
->elevator
;
1635 if (e
&& e
->type
->ops
.dispatch_request
&&
1636 !(e
->type
->elevator_features
& ELEVATOR_F_MQ_AWARE
))
1642 * Return prefered queue to dispatch from (if any) for non-mq aware IO
1645 static struct blk_mq_hw_ctx
*blk_mq_get_sq_hctx(struct request_queue
*q
)
1647 struct blk_mq_ctx
*ctx
= blk_mq_get_ctx(q
);
1649 * If the IO scheduler does not respect hardware queues when
1650 * dispatching, we just don't bother with multiple HW queues and
1651 * dispatch from hctx for the current CPU since running multiple queues
1652 * just causes lock contention inside the scheduler and pointless cache
1655 struct blk_mq_hw_ctx
*hctx
= blk_mq_map_queue(q
, 0, ctx
);
1657 if (!blk_mq_hctx_stopped(hctx
))
1663 * blk_mq_run_hw_queues - Run all hardware queues in a request queue.
1664 * @q: Pointer to the request queue to run.
1665 * @async: If we want to run the queue asynchronously.
1667 void blk_mq_run_hw_queues(struct request_queue
*q
, bool async
)
1669 struct blk_mq_hw_ctx
*hctx
, *sq_hctx
;
1673 if (blk_mq_has_sqsched(q
))
1674 sq_hctx
= blk_mq_get_sq_hctx(q
);
1675 queue_for_each_hw_ctx(q
, hctx
, i
) {
1676 if (blk_mq_hctx_stopped(hctx
))
1679 * Dispatch from this hctx either if there's no hctx preferred
1680 * by IO scheduler or if it has requests that bypass the
1683 if (!sq_hctx
|| sq_hctx
== hctx
||
1684 !list_empty_careful(&hctx
->dispatch
))
1685 blk_mq_run_hw_queue(hctx
, async
);
1688 EXPORT_SYMBOL(blk_mq_run_hw_queues
);
1691 * blk_mq_delay_run_hw_queues - Run all hardware queues asynchronously.
1692 * @q: Pointer to the request queue to run.
1693 * @msecs: Milliseconds of delay to wait before running the queues.
1695 void blk_mq_delay_run_hw_queues(struct request_queue
*q
, unsigned long msecs
)
1697 struct blk_mq_hw_ctx
*hctx
, *sq_hctx
;
1701 if (blk_mq_has_sqsched(q
))
1702 sq_hctx
= blk_mq_get_sq_hctx(q
);
1703 queue_for_each_hw_ctx(q
, hctx
, i
) {
1704 if (blk_mq_hctx_stopped(hctx
))
1707 * Dispatch from this hctx either if there's no hctx preferred
1708 * by IO scheduler or if it has requests that bypass the
1711 if (!sq_hctx
|| sq_hctx
== hctx
||
1712 !list_empty_careful(&hctx
->dispatch
))
1713 blk_mq_delay_run_hw_queue(hctx
, msecs
);
1716 EXPORT_SYMBOL(blk_mq_delay_run_hw_queues
);
1719 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1720 * @q: request queue.
1722 * The caller is responsible for serializing this function against
1723 * blk_mq_{start,stop}_hw_queue().
1725 bool blk_mq_queue_stopped(struct request_queue
*q
)
1727 struct blk_mq_hw_ctx
*hctx
;
1730 queue_for_each_hw_ctx(q
, hctx
, i
)
1731 if (blk_mq_hctx_stopped(hctx
))
1736 EXPORT_SYMBOL(blk_mq_queue_stopped
);
1739 * This function is often used for pausing .queue_rq() by driver when
1740 * there isn't enough resource or some conditions aren't satisfied, and
1741 * BLK_STS_RESOURCE is usually returned.
1743 * We do not guarantee that dispatch can be drained or blocked
1744 * after blk_mq_stop_hw_queue() returns. Please use
1745 * blk_mq_quiesce_queue() for that requirement.
1747 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1749 cancel_delayed_work(&hctx
->run_work
);
1751 set_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1753 EXPORT_SYMBOL(blk_mq_stop_hw_queue
);
1756 * This function is often used for pausing .queue_rq() by driver when
1757 * there isn't enough resource or some conditions aren't satisfied, and
1758 * BLK_STS_RESOURCE is usually returned.
1760 * We do not guarantee that dispatch can be drained or blocked
1761 * after blk_mq_stop_hw_queues() returns. Please use
1762 * blk_mq_quiesce_queue() for that requirement.
1764 void blk_mq_stop_hw_queues(struct request_queue
*q
)
1766 struct blk_mq_hw_ctx
*hctx
;
1769 queue_for_each_hw_ctx(q
, hctx
, i
)
1770 blk_mq_stop_hw_queue(hctx
);
1772 EXPORT_SYMBOL(blk_mq_stop_hw_queues
);
1774 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1776 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1778 blk_mq_run_hw_queue(hctx
, false);
1780 EXPORT_SYMBOL(blk_mq_start_hw_queue
);
1782 void blk_mq_start_hw_queues(struct request_queue
*q
)
1784 struct blk_mq_hw_ctx
*hctx
;
1787 queue_for_each_hw_ctx(q
, hctx
, i
)
1788 blk_mq_start_hw_queue(hctx
);
1790 EXPORT_SYMBOL(blk_mq_start_hw_queues
);
1792 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1794 if (!blk_mq_hctx_stopped(hctx
))
1797 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1798 blk_mq_run_hw_queue(hctx
, async
);
1800 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue
);
1802 void blk_mq_start_stopped_hw_queues(struct request_queue
*q
, bool async
)
1804 struct blk_mq_hw_ctx
*hctx
;
1807 queue_for_each_hw_ctx(q
, hctx
, i
)
1808 blk_mq_start_stopped_hw_queue(hctx
, async
);
1810 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues
);
1812 static void blk_mq_run_work_fn(struct work_struct
*work
)
1814 struct blk_mq_hw_ctx
*hctx
;
1816 hctx
= container_of(work
, struct blk_mq_hw_ctx
, run_work
.work
);
1819 * If we are stopped, don't run the queue.
1821 if (blk_mq_hctx_stopped(hctx
))
1824 __blk_mq_run_hw_queue(hctx
);
1827 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx
*hctx
,
1831 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1832 enum hctx_type type
= hctx
->type
;
1834 lockdep_assert_held(&ctx
->lock
);
1836 trace_block_rq_insert(rq
);
1839 list_add(&rq
->queuelist
, &ctx
->rq_lists
[type
]);
1841 list_add_tail(&rq
->queuelist
, &ctx
->rq_lists
[type
]);
1844 void __blk_mq_insert_request(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
,
1847 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1849 lockdep_assert_held(&ctx
->lock
);
1851 __blk_mq_insert_req_list(hctx
, rq
, at_head
);
1852 blk_mq_hctx_mark_pending(hctx
, ctx
);
1856 * blk_mq_request_bypass_insert - Insert a request at dispatch list.
1857 * @rq: Pointer to request to be inserted.
1858 * @at_head: true if the request should be inserted at the head of the list.
1859 * @run_queue: If we should run the hardware queue after inserting the request.
1861 * Should only be used carefully, when the caller knows we want to
1862 * bypass a potential IO scheduler on the target device.
1864 void blk_mq_request_bypass_insert(struct request
*rq
, bool at_head
,
1867 struct blk_mq_hw_ctx
*hctx
= rq
->mq_hctx
;
1869 spin_lock(&hctx
->lock
);
1871 list_add(&rq
->queuelist
, &hctx
->dispatch
);
1873 list_add_tail(&rq
->queuelist
, &hctx
->dispatch
);
1874 spin_unlock(&hctx
->lock
);
1877 blk_mq_run_hw_queue(hctx
, false);
1880 void blk_mq_insert_requests(struct blk_mq_hw_ctx
*hctx
, struct blk_mq_ctx
*ctx
,
1881 struct list_head
*list
)
1885 enum hctx_type type
= hctx
->type
;
1888 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1891 list_for_each_entry(rq
, list
, queuelist
) {
1892 BUG_ON(rq
->mq_ctx
!= ctx
);
1893 trace_block_rq_insert(rq
);
1896 spin_lock(&ctx
->lock
);
1897 list_splice_tail_init(list
, &ctx
->rq_lists
[type
]);
1898 blk_mq_hctx_mark_pending(hctx
, ctx
);
1899 spin_unlock(&ctx
->lock
);
1902 static int plug_rq_cmp(void *priv
, const struct list_head
*a
,
1903 const struct list_head
*b
)
1905 struct request
*rqa
= container_of(a
, struct request
, queuelist
);
1906 struct request
*rqb
= container_of(b
, struct request
, queuelist
);
1908 if (rqa
->mq_ctx
!= rqb
->mq_ctx
)
1909 return rqa
->mq_ctx
> rqb
->mq_ctx
;
1910 if (rqa
->mq_hctx
!= rqb
->mq_hctx
)
1911 return rqa
->mq_hctx
> rqb
->mq_hctx
;
1913 return blk_rq_pos(rqa
) > blk_rq_pos(rqb
);
1916 void blk_mq_flush_plug_list(struct blk_plug
*plug
, bool from_schedule
)
1920 if (list_empty(&plug
->mq_list
))
1922 list_splice_init(&plug
->mq_list
, &list
);
1924 if (plug
->rq_count
> 2 && plug
->multiple_queues
)
1925 list_sort(NULL
, &list
, plug_rq_cmp
);
1930 struct list_head rq_list
;
1931 struct request
*rq
, *head_rq
= list_entry_rq(list
.next
);
1932 struct list_head
*pos
= &head_rq
->queuelist
; /* skip first */
1933 struct blk_mq_hw_ctx
*this_hctx
= head_rq
->mq_hctx
;
1934 struct blk_mq_ctx
*this_ctx
= head_rq
->mq_ctx
;
1935 unsigned int depth
= 1;
1937 list_for_each_continue(pos
, &list
) {
1938 rq
= list_entry_rq(pos
);
1940 if (rq
->mq_hctx
!= this_hctx
|| rq
->mq_ctx
!= this_ctx
)
1945 list_cut_before(&rq_list
, &list
, pos
);
1946 trace_block_unplug(head_rq
->q
, depth
, !from_schedule
);
1947 blk_mq_sched_insert_requests(this_hctx
, this_ctx
, &rq_list
,
1949 } while(!list_empty(&list
));
1952 static void blk_mq_bio_to_request(struct request
*rq
, struct bio
*bio
,
1953 unsigned int nr_segs
)
1957 if (bio
->bi_opf
& REQ_RAHEAD
)
1958 rq
->cmd_flags
|= REQ_FAILFAST_MASK
;
1960 rq
->__sector
= bio
->bi_iter
.bi_sector
;
1961 rq
->write_hint
= bio
->bi_write_hint
;
1962 blk_rq_bio_prep(rq
, bio
, nr_segs
);
1964 /* This can't fail, since GFP_NOIO includes __GFP_DIRECT_RECLAIM. */
1965 err
= blk_crypto_rq_bio_prep(rq
, bio
, GFP_NOIO
);
1968 blk_account_io_start(rq
);
1971 static blk_status_t
__blk_mq_issue_directly(struct blk_mq_hw_ctx
*hctx
,
1973 blk_qc_t
*cookie
, bool last
)
1975 struct request_queue
*q
= rq
->q
;
1976 struct blk_mq_queue_data bd
= {
1980 blk_qc_t new_cookie
;
1983 new_cookie
= request_to_qc_t(hctx
, rq
);
1986 * For OK queue, we are done. For error, caller may kill it.
1987 * Any other error (busy), just add it to our list as we
1988 * previously would have done.
1990 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1993 blk_mq_update_dispatch_busy(hctx
, false);
1994 *cookie
= new_cookie
;
1996 case BLK_STS_RESOURCE
:
1997 case BLK_STS_DEV_RESOURCE
:
1998 blk_mq_update_dispatch_busy(hctx
, true);
1999 __blk_mq_requeue_request(rq
);
2002 blk_mq_update_dispatch_busy(hctx
, false);
2003 *cookie
= BLK_QC_T_NONE
;
2010 static blk_status_t
__blk_mq_try_issue_directly(struct blk_mq_hw_ctx
*hctx
,
2013 bool bypass_insert
, bool last
)
2015 struct request_queue
*q
= rq
->q
;
2016 bool run_queue
= true;
2020 * RCU or SRCU read lock is needed before checking quiesced flag.
2022 * When queue is stopped or quiesced, ignore 'bypass_insert' from
2023 * blk_mq_request_issue_directly(), and return BLK_STS_OK to caller,
2024 * and avoid driver to try to dispatch again.
2026 if (blk_mq_hctx_stopped(hctx
) || blk_queue_quiesced(q
)) {
2028 bypass_insert
= false;
2032 if (q
->elevator
&& !bypass_insert
)
2035 budget_token
= blk_mq_get_dispatch_budget(q
);
2036 if (budget_token
< 0)
2039 blk_mq_set_rq_budget_token(rq
, budget_token
);
2041 if (!blk_mq_get_driver_tag(rq
)) {
2042 blk_mq_put_dispatch_budget(q
, budget_token
);
2046 return __blk_mq_issue_directly(hctx
, rq
, cookie
, last
);
2049 return BLK_STS_RESOURCE
;
2051 blk_mq_sched_insert_request(rq
, false, run_queue
, false);
2057 * blk_mq_try_issue_directly - Try to send a request directly to device driver.
2058 * @hctx: Pointer of the associated hardware queue.
2059 * @rq: Pointer to request to be sent.
2060 * @cookie: Request queue cookie.
2062 * If the device has enough resources to accept a new request now, send the
2063 * request directly to device driver. Else, insert at hctx->dispatch queue, so
2064 * we can try send it another time in the future. Requests inserted at this
2065 * queue have higher priority.
2067 static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx
*hctx
,
2068 struct request
*rq
, blk_qc_t
*cookie
)
2073 might_sleep_if(hctx
->flags
& BLK_MQ_F_BLOCKING
);
2075 hctx_lock(hctx
, &srcu_idx
);
2077 ret
= __blk_mq_try_issue_directly(hctx
, rq
, cookie
, false, true);
2078 if (ret
== BLK_STS_RESOURCE
|| ret
== BLK_STS_DEV_RESOURCE
)
2079 blk_mq_request_bypass_insert(rq
, false, true);
2080 else if (ret
!= BLK_STS_OK
)
2081 blk_mq_end_request(rq
, ret
);
2083 hctx_unlock(hctx
, srcu_idx
);
2086 blk_status_t
blk_mq_request_issue_directly(struct request
*rq
, bool last
)
2090 blk_qc_t unused_cookie
;
2091 struct blk_mq_hw_ctx
*hctx
= rq
->mq_hctx
;
2093 hctx_lock(hctx
, &srcu_idx
);
2094 ret
= __blk_mq_try_issue_directly(hctx
, rq
, &unused_cookie
, true, last
);
2095 hctx_unlock(hctx
, srcu_idx
);
2100 void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx
*hctx
,
2101 struct list_head
*list
)
2106 while (!list_empty(list
)) {
2108 struct request
*rq
= list_first_entry(list
, struct request
,
2111 list_del_init(&rq
->queuelist
);
2112 ret
= blk_mq_request_issue_directly(rq
, list_empty(list
));
2113 if (ret
!= BLK_STS_OK
) {
2114 if (ret
== BLK_STS_RESOURCE
||
2115 ret
== BLK_STS_DEV_RESOURCE
) {
2116 blk_mq_request_bypass_insert(rq
, false,
2120 blk_mq_end_request(rq
, ret
);
2127 * If we didn't flush the entire list, we could have told
2128 * the driver there was more coming, but that turned out to
2131 if ((!list_empty(list
) || errors
) &&
2132 hctx
->queue
->mq_ops
->commit_rqs
&& queued
)
2133 hctx
->queue
->mq_ops
->commit_rqs(hctx
);
2136 static void blk_add_rq_to_plug(struct blk_plug
*plug
, struct request
*rq
)
2138 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
2140 if (!plug
->multiple_queues
&& !list_is_singular(&plug
->mq_list
)) {
2141 struct request
*tmp
;
2143 tmp
= list_first_entry(&plug
->mq_list
, struct request
,
2145 if (tmp
->q
!= rq
->q
)
2146 plug
->multiple_queues
= true;
2151 * Allow 2x BLK_MAX_REQUEST_COUNT requests on plug queue for multiple
2152 * queues. This is important for md arrays to benefit from merging
2155 static inline unsigned short blk_plug_max_rq_count(struct blk_plug
*plug
)
2157 if (plug
->multiple_queues
)
2158 return BLK_MAX_REQUEST_COUNT
* 2;
2159 return BLK_MAX_REQUEST_COUNT
;
2163 * blk_mq_submit_bio - Create and send a request to block device.
2164 * @bio: Bio pointer.
2166 * Builds up a request structure from @q and @bio and send to the device. The
2167 * request may not be queued directly to hardware if:
2168 * * This request can be merged with another one
2169 * * We want to place request at plug queue for possible future merging
2170 * * There is an IO scheduler active at this queue
2172 * It will not queue the request if there is an error with the bio, or at the
2175 * Returns: Request queue cookie.
2177 blk_qc_t
blk_mq_submit_bio(struct bio
*bio
)
2179 struct request_queue
*q
= bio
->bi_bdev
->bd_disk
->queue
;
2180 const int is_sync
= op_is_sync(bio
->bi_opf
);
2181 const int is_flush_fua
= op_is_flush(bio
->bi_opf
);
2182 struct blk_mq_alloc_data data
= {
2186 struct blk_plug
*plug
;
2187 struct request
*same_queue_rq
= NULL
;
2188 unsigned int nr_segs
;
2193 blk_queue_bounce(q
, &bio
);
2194 __blk_queue_split(&bio
, &nr_segs
);
2196 if (!bio_integrity_prep(bio
))
2199 if (!is_flush_fua
&& !blk_queue_nomerges(q
) &&
2200 blk_attempt_plug_merge(q
, bio
, nr_segs
, &same_queue_rq
))
2203 if (blk_mq_sched_bio_merge(q
, bio
, nr_segs
))
2206 rq_qos_throttle(q
, bio
);
2208 hipri
= bio
->bi_opf
& REQ_HIPRI
;
2210 data
.cmd_flags
= bio
->bi_opf
;
2211 rq
= __blk_mq_alloc_request(&data
);
2212 if (unlikely(!rq
)) {
2213 rq_qos_cleanup(q
, bio
);
2214 if (bio
->bi_opf
& REQ_NOWAIT
)
2215 bio_wouldblock_error(bio
);
2219 trace_block_getrq(bio
);
2221 rq_qos_track(q
, rq
, bio
);
2223 cookie
= request_to_qc_t(data
.hctx
, rq
);
2225 blk_mq_bio_to_request(rq
, bio
, nr_segs
);
2227 ret
= blk_crypto_init_request(rq
);
2228 if (ret
!= BLK_STS_OK
) {
2229 bio
->bi_status
= ret
;
2231 blk_mq_free_request(rq
);
2232 return BLK_QC_T_NONE
;
2235 plug
= blk_mq_plug(q
, bio
);
2236 if (unlikely(is_flush_fua
)) {
2237 /* Bypass scheduler for flush requests */
2238 blk_insert_flush(rq
);
2239 blk_mq_run_hw_queue(data
.hctx
, true);
2240 } else if (plug
&& (q
->nr_hw_queues
== 1 ||
2241 blk_mq_is_sbitmap_shared(rq
->mq_hctx
->flags
) ||
2242 q
->mq_ops
->commit_rqs
|| !blk_queue_nonrot(q
))) {
2244 * Use plugging if we have a ->commit_rqs() hook as well, as
2245 * we know the driver uses bd->last in a smart fashion.
2247 * Use normal plugging if this disk is slow HDD, as sequential
2248 * IO may benefit a lot from plug merging.
2250 unsigned int request_count
= plug
->rq_count
;
2251 struct request
*last
= NULL
;
2254 trace_block_plug(q
);
2256 last
= list_entry_rq(plug
->mq_list
.prev
);
2258 if (request_count
>= blk_plug_max_rq_count(plug
) || (last
&&
2259 blk_rq_bytes(last
) >= BLK_PLUG_FLUSH_SIZE
)) {
2260 blk_flush_plug_list(plug
, false);
2261 trace_block_plug(q
);
2264 blk_add_rq_to_plug(plug
, rq
);
2265 } else if (q
->elevator
) {
2266 /* Insert the request at the IO scheduler queue */
2267 blk_mq_sched_insert_request(rq
, false, true, true);
2268 } else if (plug
&& !blk_queue_nomerges(q
)) {
2270 * We do limited plugging. If the bio can be merged, do that.
2271 * Otherwise the existing request in the plug list will be
2272 * issued. So the plug list will have one request at most
2273 * The plug list might get flushed before this. If that happens,
2274 * the plug list is empty, and same_queue_rq is invalid.
2276 if (list_empty(&plug
->mq_list
))
2277 same_queue_rq
= NULL
;
2278 if (same_queue_rq
) {
2279 list_del_init(&same_queue_rq
->queuelist
);
2282 blk_add_rq_to_plug(plug
, rq
);
2283 trace_block_plug(q
);
2285 if (same_queue_rq
) {
2286 data
.hctx
= same_queue_rq
->mq_hctx
;
2287 trace_block_unplug(q
, 1, true);
2288 blk_mq_try_issue_directly(data
.hctx
, same_queue_rq
,
2291 } else if ((q
->nr_hw_queues
> 1 && is_sync
) ||
2292 !data
.hctx
->dispatch_busy
) {
2294 * There is no scheduler and we can try to send directly
2297 blk_mq_try_issue_directly(data
.hctx
, rq
, &cookie
);
2300 blk_mq_sched_insert_request(rq
, false, true, true);
2304 return BLK_QC_T_NONE
;
2308 return BLK_QC_T_NONE
;
2311 static size_t order_to_size(unsigned int order
)
2313 return (size_t)PAGE_SIZE
<< order
;
2316 /* called before freeing request pool in @tags */
2317 static void blk_mq_clear_rq_mapping(struct blk_mq_tag_set
*set
,
2318 struct blk_mq_tags
*tags
, unsigned int hctx_idx
)
2320 struct blk_mq_tags
*drv_tags
= set
->tags
[hctx_idx
];
2322 unsigned long flags
;
2324 list_for_each_entry(page
, &tags
->page_list
, lru
) {
2325 unsigned long start
= (unsigned long)page_address(page
);
2326 unsigned long end
= start
+ order_to_size(page
->private);
2329 for (i
= 0; i
< set
->queue_depth
; i
++) {
2330 struct request
*rq
= drv_tags
->rqs
[i
];
2331 unsigned long rq_addr
= (unsigned long)rq
;
2333 if (rq_addr
>= start
&& rq_addr
< end
) {
2334 WARN_ON_ONCE(refcount_read(&rq
->ref
) != 0);
2335 cmpxchg(&drv_tags
->rqs
[i
], rq
, NULL
);
2341 * Wait until all pending iteration is done.
2343 * Request reference is cleared and it is guaranteed to be observed
2344 * after the ->lock is released.
2346 spin_lock_irqsave(&drv_tags
->lock
, flags
);
2347 spin_unlock_irqrestore(&drv_tags
->lock
, flags
);
2350 void blk_mq_free_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
2351 unsigned int hctx_idx
)
2355 if (tags
->rqs
&& set
->ops
->exit_request
) {
2358 for (i
= 0; i
< tags
->nr_tags
; i
++) {
2359 struct request
*rq
= tags
->static_rqs
[i
];
2363 set
->ops
->exit_request(set
, rq
, hctx_idx
);
2364 tags
->static_rqs
[i
] = NULL
;
2368 blk_mq_clear_rq_mapping(set
, tags
, hctx_idx
);
2370 while (!list_empty(&tags
->page_list
)) {
2371 page
= list_first_entry(&tags
->page_list
, struct page
, lru
);
2372 list_del_init(&page
->lru
);
2374 * Remove kmemleak object previously allocated in
2375 * blk_mq_alloc_rqs().
2377 kmemleak_free(page_address(page
));
2378 __free_pages(page
, page
->private);
2382 void blk_mq_free_rq_map(struct blk_mq_tags
*tags
, unsigned int flags
)
2386 kfree(tags
->static_rqs
);
2387 tags
->static_rqs
= NULL
;
2389 blk_mq_free_tags(tags
, flags
);
2392 struct blk_mq_tags
*blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
,
2393 unsigned int hctx_idx
,
2394 unsigned int nr_tags
,
2395 unsigned int reserved_tags
,
2398 struct blk_mq_tags
*tags
;
2401 node
= blk_mq_hw_queue_to_node(&set
->map
[HCTX_TYPE_DEFAULT
], hctx_idx
);
2402 if (node
== NUMA_NO_NODE
)
2403 node
= set
->numa_node
;
2405 tags
= blk_mq_init_tags(nr_tags
, reserved_tags
, node
, flags
);
2409 tags
->rqs
= kcalloc_node(nr_tags
, sizeof(struct request
*),
2410 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
2413 blk_mq_free_tags(tags
, flags
);
2417 tags
->static_rqs
= kcalloc_node(nr_tags
, sizeof(struct request
*),
2418 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
2420 if (!tags
->static_rqs
) {
2422 blk_mq_free_tags(tags
, flags
);
2429 static int blk_mq_init_request(struct blk_mq_tag_set
*set
, struct request
*rq
,
2430 unsigned int hctx_idx
, int node
)
2434 if (set
->ops
->init_request
) {
2435 ret
= set
->ops
->init_request(set
, rq
, hctx_idx
, node
);
2440 WRITE_ONCE(rq
->state
, MQ_RQ_IDLE
);
2444 int blk_mq_alloc_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
2445 unsigned int hctx_idx
, unsigned int depth
)
2447 unsigned int i
, j
, entries_per_page
, max_order
= 4;
2448 size_t rq_size
, left
;
2451 node
= blk_mq_hw_queue_to_node(&set
->map
[HCTX_TYPE_DEFAULT
], hctx_idx
);
2452 if (node
== NUMA_NO_NODE
)
2453 node
= set
->numa_node
;
2455 INIT_LIST_HEAD(&tags
->page_list
);
2458 * rq_size is the size of the request plus driver payload, rounded
2459 * to the cacheline size
2461 rq_size
= round_up(sizeof(struct request
) + set
->cmd_size
,
2463 left
= rq_size
* depth
;
2465 for (i
= 0; i
< depth
; ) {
2466 int this_order
= max_order
;
2471 while (this_order
&& left
< order_to_size(this_order
- 1))
2475 page
= alloc_pages_node(node
,
2476 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
| __GFP_ZERO
,
2482 if (order_to_size(this_order
) < rq_size
)
2489 page
->private = this_order
;
2490 list_add_tail(&page
->lru
, &tags
->page_list
);
2492 p
= page_address(page
);
2494 * Allow kmemleak to scan these pages as they contain pointers
2495 * to additional allocations like via ops->init_request().
2497 kmemleak_alloc(p
, order_to_size(this_order
), 1, GFP_NOIO
);
2498 entries_per_page
= order_to_size(this_order
) / rq_size
;
2499 to_do
= min(entries_per_page
, depth
- i
);
2500 left
-= to_do
* rq_size
;
2501 for (j
= 0; j
< to_do
; j
++) {
2502 struct request
*rq
= p
;
2504 tags
->static_rqs
[i
] = rq
;
2505 if (blk_mq_init_request(set
, rq
, hctx_idx
, node
)) {
2506 tags
->static_rqs
[i
] = NULL
;
2517 blk_mq_free_rqs(set
, tags
, hctx_idx
);
2521 struct rq_iter_data
{
2522 struct blk_mq_hw_ctx
*hctx
;
2526 static bool blk_mq_has_request(struct request
*rq
, void *data
, bool reserved
)
2528 struct rq_iter_data
*iter_data
= data
;
2530 if (rq
->mq_hctx
!= iter_data
->hctx
)
2532 iter_data
->has_rq
= true;
2536 static bool blk_mq_hctx_has_requests(struct blk_mq_hw_ctx
*hctx
)
2538 struct blk_mq_tags
*tags
= hctx
->sched_tags
?
2539 hctx
->sched_tags
: hctx
->tags
;
2540 struct rq_iter_data data
= {
2544 blk_mq_all_tag_iter(tags
, blk_mq_has_request
, &data
);
2548 static inline bool blk_mq_last_cpu_in_hctx(unsigned int cpu
,
2549 struct blk_mq_hw_ctx
*hctx
)
2551 if (cpumask_next_and(-1, hctx
->cpumask
, cpu_online_mask
) != cpu
)
2553 if (cpumask_next_and(cpu
, hctx
->cpumask
, cpu_online_mask
) < nr_cpu_ids
)
2558 static int blk_mq_hctx_notify_offline(unsigned int cpu
, struct hlist_node
*node
)
2560 struct blk_mq_hw_ctx
*hctx
= hlist_entry_safe(node
,
2561 struct blk_mq_hw_ctx
, cpuhp_online
);
2563 if (!cpumask_test_cpu(cpu
, hctx
->cpumask
) ||
2564 !blk_mq_last_cpu_in_hctx(cpu
, hctx
))
2568 * Prevent new request from being allocated on the current hctx.
2570 * The smp_mb__after_atomic() Pairs with the implied barrier in
2571 * test_and_set_bit_lock in sbitmap_get(). Ensures the inactive flag is
2572 * seen once we return from the tag allocator.
2574 set_bit(BLK_MQ_S_INACTIVE
, &hctx
->state
);
2575 smp_mb__after_atomic();
2578 * Try to grab a reference to the queue and wait for any outstanding
2579 * requests. If we could not grab a reference the queue has been
2580 * frozen and there are no requests.
2582 if (percpu_ref_tryget(&hctx
->queue
->q_usage_counter
)) {
2583 while (blk_mq_hctx_has_requests(hctx
))
2585 percpu_ref_put(&hctx
->queue
->q_usage_counter
);
2591 static int blk_mq_hctx_notify_online(unsigned int cpu
, struct hlist_node
*node
)
2593 struct blk_mq_hw_ctx
*hctx
= hlist_entry_safe(node
,
2594 struct blk_mq_hw_ctx
, cpuhp_online
);
2596 if (cpumask_test_cpu(cpu
, hctx
->cpumask
))
2597 clear_bit(BLK_MQ_S_INACTIVE
, &hctx
->state
);
2602 * 'cpu' is going away. splice any existing rq_list entries from this
2603 * software queue to the hw queue dispatch list, and ensure that it
2606 static int blk_mq_hctx_notify_dead(unsigned int cpu
, struct hlist_node
*node
)
2608 struct blk_mq_hw_ctx
*hctx
;
2609 struct blk_mq_ctx
*ctx
;
2611 enum hctx_type type
;
2613 hctx
= hlist_entry_safe(node
, struct blk_mq_hw_ctx
, cpuhp_dead
);
2614 if (!cpumask_test_cpu(cpu
, hctx
->cpumask
))
2617 ctx
= __blk_mq_get_ctx(hctx
->queue
, cpu
);
2620 spin_lock(&ctx
->lock
);
2621 if (!list_empty(&ctx
->rq_lists
[type
])) {
2622 list_splice_init(&ctx
->rq_lists
[type
], &tmp
);
2623 blk_mq_hctx_clear_pending(hctx
, ctx
);
2625 spin_unlock(&ctx
->lock
);
2627 if (list_empty(&tmp
))
2630 spin_lock(&hctx
->lock
);
2631 list_splice_tail_init(&tmp
, &hctx
->dispatch
);
2632 spin_unlock(&hctx
->lock
);
2634 blk_mq_run_hw_queue(hctx
, true);
2638 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx
*hctx
)
2640 if (!(hctx
->flags
& BLK_MQ_F_STACKING
))
2641 cpuhp_state_remove_instance_nocalls(CPUHP_AP_BLK_MQ_ONLINE
,
2642 &hctx
->cpuhp_online
);
2643 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD
,
2648 * Before freeing hw queue, clearing the flush request reference in
2649 * tags->rqs[] for avoiding potential UAF.
2651 static void blk_mq_clear_flush_rq_mapping(struct blk_mq_tags
*tags
,
2652 unsigned int queue_depth
, struct request
*flush_rq
)
2655 unsigned long flags
;
2657 /* The hw queue may not be mapped yet */
2661 WARN_ON_ONCE(refcount_read(&flush_rq
->ref
) != 0);
2663 for (i
= 0; i
< queue_depth
; i
++)
2664 cmpxchg(&tags
->rqs
[i
], flush_rq
, NULL
);
2667 * Wait until all pending iteration is done.
2669 * Request reference is cleared and it is guaranteed to be observed
2670 * after the ->lock is released.
2672 spin_lock_irqsave(&tags
->lock
, flags
);
2673 spin_unlock_irqrestore(&tags
->lock
, flags
);
2676 /* hctx->ctxs will be freed in queue's release handler */
2677 static void blk_mq_exit_hctx(struct request_queue
*q
,
2678 struct blk_mq_tag_set
*set
,
2679 struct blk_mq_hw_ctx
*hctx
, unsigned int hctx_idx
)
2681 struct request
*flush_rq
= hctx
->fq
->flush_rq
;
2683 if (blk_mq_hw_queue_mapped(hctx
))
2684 blk_mq_tag_idle(hctx
);
2686 blk_mq_clear_flush_rq_mapping(set
->tags
[hctx_idx
],
2687 set
->queue_depth
, flush_rq
);
2688 if (set
->ops
->exit_request
)
2689 set
->ops
->exit_request(set
, flush_rq
, hctx_idx
);
2691 if (set
->ops
->exit_hctx
)
2692 set
->ops
->exit_hctx(hctx
, hctx_idx
);
2694 blk_mq_remove_cpuhp(hctx
);
2696 spin_lock(&q
->unused_hctx_lock
);
2697 list_add(&hctx
->hctx_list
, &q
->unused_hctx_list
);
2698 spin_unlock(&q
->unused_hctx_lock
);
2701 static void blk_mq_exit_hw_queues(struct request_queue
*q
,
2702 struct blk_mq_tag_set
*set
, int nr_queue
)
2704 struct blk_mq_hw_ctx
*hctx
;
2707 queue_for_each_hw_ctx(q
, hctx
, i
) {
2710 blk_mq_debugfs_unregister_hctx(hctx
);
2711 blk_mq_exit_hctx(q
, set
, hctx
, i
);
2715 static int blk_mq_hw_ctx_size(struct blk_mq_tag_set
*tag_set
)
2717 int hw_ctx_size
= sizeof(struct blk_mq_hw_ctx
);
2719 BUILD_BUG_ON(ALIGN(offsetof(struct blk_mq_hw_ctx
, srcu
),
2720 __alignof__(struct blk_mq_hw_ctx
)) !=
2721 sizeof(struct blk_mq_hw_ctx
));
2723 if (tag_set
->flags
& BLK_MQ_F_BLOCKING
)
2724 hw_ctx_size
+= sizeof(struct srcu_struct
);
2729 static int blk_mq_init_hctx(struct request_queue
*q
,
2730 struct blk_mq_tag_set
*set
,
2731 struct blk_mq_hw_ctx
*hctx
, unsigned hctx_idx
)
2733 hctx
->queue_num
= hctx_idx
;
2735 if (!(hctx
->flags
& BLK_MQ_F_STACKING
))
2736 cpuhp_state_add_instance_nocalls(CPUHP_AP_BLK_MQ_ONLINE
,
2737 &hctx
->cpuhp_online
);
2738 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD
, &hctx
->cpuhp_dead
);
2740 hctx
->tags
= set
->tags
[hctx_idx
];
2742 if (set
->ops
->init_hctx
&&
2743 set
->ops
->init_hctx(hctx
, set
->driver_data
, hctx_idx
))
2744 goto unregister_cpu_notifier
;
2746 if (blk_mq_init_request(set
, hctx
->fq
->flush_rq
, hctx_idx
,
2752 if (set
->ops
->exit_hctx
)
2753 set
->ops
->exit_hctx(hctx
, hctx_idx
);
2754 unregister_cpu_notifier
:
2755 blk_mq_remove_cpuhp(hctx
);
2759 static struct blk_mq_hw_ctx
*
2760 blk_mq_alloc_hctx(struct request_queue
*q
, struct blk_mq_tag_set
*set
,
2763 struct blk_mq_hw_ctx
*hctx
;
2764 gfp_t gfp
= GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
;
2766 hctx
= kzalloc_node(blk_mq_hw_ctx_size(set
), gfp
, node
);
2768 goto fail_alloc_hctx
;
2770 if (!zalloc_cpumask_var_node(&hctx
->cpumask
, gfp
, node
))
2773 atomic_set(&hctx
->nr_active
, 0);
2774 if (node
== NUMA_NO_NODE
)
2775 node
= set
->numa_node
;
2776 hctx
->numa_node
= node
;
2778 INIT_DELAYED_WORK(&hctx
->run_work
, blk_mq_run_work_fn
);
2779 spin_lock_init(&hctx
->lock
);
2780 INIT_LIST_HEAD(&hctx
->dispatch
);
2782 hctx
->flags
= set
->flags
& ~BLK_MQ_F_TAG_QUEUE_SHARED
;
2784 INIT_LIST_HEAD(&hctx
->hctx_list
);
2787 * Allocate space for all possible cpus to avoid allocation at
2790 hctx
->ctxs
= kmalloc_array_node(nr_cpu_ids
, sizeof(void *),
2795 if (sbitmap_init_node(&hctx
->ctx_map
, nr_cpu_ids
, ilog2(8),
2796 gfp
, node
, false, false))
2800 spin_lock_init(&hctx
->dispatch_wait_lock
);
2801 init_waitqueue_func_entry(&hctx
->dispatch_wait
, blk_mq_dispatch_wake
);
2802 INIT_LIST_HEAD(&hctx
->dispatch_wait
.entry
);
2804 hctx
->fq
= blk_alloc_flush_queue(hctx
->numa_node
, set
->cmd_size
, gfp
);
2808 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
2809 init_srcu_struct(hctx
->srcu
);
2810 blk_mq_hctx_kobj_init(hctx
);
2815 sbitmap_free(&hctx
->ctx_map
);
2819 free_cpumask_var(hctx
->cpumask
);
2826 static void blk_mq_init_cpu_queues(struct request_queue
*q
,
2827 unsigned int nr_hw_queues
)
2829 struct blk_mq_tag_set
*set
= q
->tag_set
;
2832 for_each_possible_cpu(i
) {
2833 struct blk_mq_ctx
*__ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
2834 struct blk_mq_hw_ctx
*hctx
;
2838 spin_lock_init(&__ctx
->lock
);
2839 for (k
= HCTX_TYPE_DEFAULT
; k
< HCTX_MAX_TYPES
; k
++)
2840 INIT_LIST_HEAD(&__ctx
->rq_lists
[k
]);
2845 * Set local node, IFF we have more than one hw queue. If
2846 * not, we remain on the home node of the device
2848 for (j
= 0; j
< set
->nr_maps
; j
++) {
2849 hctx
= blk_mq_map_queue_type(q
, j
, i
);
2850 if (nr_hw_queues
> 1 && hctx
->numa_node
== NUMA_NO_NODE
)
2851 hctx
->numa_node
= cpu_to_node(i
);
2856 static bool __blk_mq_alloc_map_and_request(struct blk_mq_tag_set
*set
,
2859 unsigned int flags
= set
->flags
;
2862 set
->tags
[hctx_idx
] = blk_mq_alloc_rq_map(set
, hctx_idx
,
2863 set
->queue_depth
, set
->reserved_tags
, flags
);
2864 if (!set
->tags
[hctx_idx
])
2867 ret
= blk_mq_alloc_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
,
2872 blk_mq_free_rq_map(set
->tags
[hctx_idx
], flags
);
2873 set
->tags
[hctx_idx
] = NULL
;
2877 static void blk_mq_free_map_and_requests(struct blk_mq_tag_set
*set
,
2878 unsigned int hctx_idx
)
2880 unsigned int flags
= set
->flags
;
2882 if (set
->tags
&& set
->tags
[hctx_idx
]) {
2883 blk_mq_free_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
);
2884 blk_mq_free_rq_map(set
->tags
[hctx_idx
], flags
);
2885 set
->tags
[hctx_idx
] = NULL
;
2889 static void blk_mq_map_swqueue(struct request_queue
*q
)
2891 unsigned int i
, j
, hctx_idx
;
2892 struct blk_mq_hw_ctx
*hctx
;
2893 struct blk_mq_ctx
*ctx
;
2894 struct blk_mq_tag_set
*set
= q
->tag_set
;
2896 queue_for_each_hw_ctx(q
, hctx
, i
) {
2897 cpumask_clear(hctx
->cpumask
);
2899 hctx
->dispatch_from
= NULL
;
2903 * Map software to hardware queues.
2905 * If the cpu isn't present, the cpu is mapped to first hctx.
2907 for_each_possible_cpu(i
) {
2909 ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
2910 for (j
= 0; j
< set
->nr_maps
; j
++) {
2911 if (!set
->map
[j
].nr_queues
) {
2912 ctx
->hctxs
[j
] = blk_mq_map_queue_type(q
,
2913 HCTX_TYPE_DEFAULT
, i
);
2916 hctx_idx
= set
->map
[j
].mq_map
[i
];
2917 /* unmapped hw queue can be remapped after CPU topo changed */
2918 if (!set
->tags
[hctx_idx
] &&
2919 !__blk_mq_alloc_map_and_request(set
, hctx_idx
)) {
2921 * If tags initialization fail for some hctx,
2922 * that hctx won't be brought online. In this
2923 * case, remap the current ctx to hctx[0] which
2924 * is guaranteed to always have tags allocated
2926 set
->map
[j
].mq_map
[i
] = 0;
2929 hctx
= blk_mq_map_queue_type(q
, j
, i
);
2930 ctx
->hctxs
[j
] = hctx
;
2932 * If the CPU is already set in the mask, then we've
2933 * mapped this one already. This can happen if
2934 * devices share queues across queue maps.
2936 if (cpumask_test_cpu(i
, hctx
->cpumask
))
2939 cpumask_set_cpu(i
, hctx
->cpumask
);
2941 ctx
->index_hw
[hctx
->type
] = hctx
->nr_ctx
;
2942 hctx
->ctxs
[hctx
->nr_ctx
++] = ctx
;
2945 * If the nr_ctx type overflows, we have exceeded the
2946 * amount of sw queues we can support.
2948 BUG_ON(!hctx
->nr_ctx
);
2951 for (; j
< HCTX_MAX_TYPES
; j
++)
2952 ctx
->hctxs
[j
] = blk_mq_map_queue_type(q
,
2953 HCTX_TYPE_DEFAULT
, i
);
2956 queue_for_each_hw_ctx(q
, hctx
, i
) {
2958 * If no software queues are mapped to this hardware queue,
2959 * disable it and free the request entries.
2961 if (!hctx
->nr_ctx
) {
2962 /* Never unmap queue 0. We need it as a
2963 * fallback in case of a new remap fails
2966 if (i
&& set
->tags
[i
])
2967 blk_mq_free_map_and_requests(set
, i
);
2973 hctx
->tags
= set
->tags
[i
];
2974 WARN_ON(!hctx
->tags
);
2977 * Set the map size to the number of mapped software queues.
2978 * This is more accurate and more efficient than looping
2979 * over all possibly mapped software queues.
2981 sbitmap_resize(&hctx
->ctx_map
, hctx
->nr_ctx
);
2984 * Initialize batch roundrobin counts
2986 hctx
->next_cpu
= blk_mq_first_mapped_cpu(hctx
);
2987 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
2992 * Caller needs to ensure that we're either frozen/quiesced, or that
2993 * the queue isn't live yet.
2995 static void queue_set_hctx_shared(struct request_queue
*q
, bool shared
)
2997 struct blk_mq_hw_ctx
*hctx
;
3000 queue_for_each_hw_ctx(q
, hctx
, i
) {
3002 hctx
->flags
|= BLK_MQ_F_TAG_QUEUE_SHARED
;
3004 blk_mq_tag_idle(hctx
);
3005 hctx
->flags
&= ~BLK_MQ_F_TAG_QUEUE_SHARED
;
3010 static void blk_mq_update_tag_set_shared(struct blk_mq_tag_set
*set
,
3013 struct request_queue
*q
;
3015 lockdep_assert_held(&set
->tag_list_lock
);
3017 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
3018 blk_mq_freeze_queue(q
);
3019 queue_set_hctx_shared(q
, shared
);
3020 blk_mq_unfreeze_queue(q
);
3024 static void blk_mq_del_queue_tag_set(struct request_queue
*q
)
3026 struct blk_mq_tag_set
*set
= q
->tag_set
;
3028 mutex_lock(&set
->tag_list_lock
);
3029 list_del(&q
->tag_set_list
);
3030 if (list_is_singular(&set
->tag_list
)) {
3031 /* just transitioned to unshared */
3032 set
->flags
&= ~BLK_MQ_F_TAG_QUEUE_SHARED
;
3033 /* update existing queue */
3034 blk_mq_update_tag_set_shared(set
, false);
3036 mutex_unlock(&set
->tag_list_lock
);
3037 INIT_LIST_HEAD(&q
->tag_set_list
);
3040 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set
*set
,
3041 struct request_queue
*q
)
3043 mutex_lock(&set
->tag_list_lock
);
3046 * Check to see if we're transitioning to shared (from 1 to 2 queues).
3048 if (!list_empty(&set
->tag_list
) &&
3049 !(set
->flags
& BLK_MQ_F_TAG_QUEUE_SHARED
)) {
3050 set
->flags
|= BLK_MQ_F_TAG_QUEUE_SHARED
;
3051 /* update existing queue */
3052 blk_mq_update_tag_set_shared(set
, true);
3054 if (set
->flags
& BLK_MQ_F_TAG_QUEUE_SHARED
)
3055 queue_set_hctx_shared(q
, true);
3056 list_add_tail(&q
->tag_set_list
, &set
->tag_list
);
3058 mutex_unlock(&set
->tag_list_lock
);
3061 /* All allocations will be freed in release handler of q->mq_kobj */
3062 static int blk_mq_alloc_ctxs(struct request_queue
*q
)
3064 struct blk_mq_ctxs
*ctxs
;
3067 ctxs
= kzalloc(sizeof(*ctxs
), GFP_KERNEL
);
3071 ctxs
->queue_ctx
= alloc_percpu(struct blk_mq_ctx
);
3072 if (!ctxs
->queue_ctx
)
3075 for_each_possible_cpu(cpu
) {
3076 struct blk_mq_ctx
*ctx
= per_cpu_ptr(ctxs
->queue_ctx
, cpu
);
3080 q
->mq_kobj
= &ctxs
->kobj
;
3081 q
->queue_ctx
= ctxs
->queue_ctx
;
3090 * It is the actual release handler for mq, but we do it from
3091 * request queue's release handler for avoiding use-after-free
3092 * and headache because q->mq_kobj shouldn't have been introduced,
3093 * but we can't group ctx/kctx kobj without it.
3095 void blk_mq_release(struct request_queue
*q
)
3097 struct blk_mq_hw_ctx
*hctx
, *next
;
3100 queue_for_each_hw_ctx(q
, hctx
, i
)
3101 WARN_ON_ONCE(hctx
&& list_empty(&hctx
->hctx_list
));
3103 /* all hctx are in .unused_hctx_list now */
3104 list_for_each_entry_safe(hctx
, next
, &q
->unused_hctx_list
, hctx_list
) {
3105 list_del_init(&hctx
->hctx_list
);
3106 kobject_put(&hctx
->kobj
);
3109 kfree(q
->queue_hw_ctx
);
3112 * release .mq_kobj and sw queue's kobject now because
3113 * both share lifetime with request queue.
3115 blk_mq_sysfs_deinit(q
);
3118 static struct request_queue
*blk_mq_init_queue_data(struct blk_mq_tag_set
*set
,
3121 struct request_queue
*q
;
3124 q
= blk_alloc_queue(set
->numa_node
);
3126 return ERR_PTR(-ENOMEM
);
3127 q
->queuedata
= queuedata
;
3128 ret
= blk_mq_init_allocated_queue(set
, q
);
3130 blk_cleanup_queue(q
);
3131 return ERR_PTR(ret
);
3136 struct request_queue
*blk_mq_init_queue(struct blk_mq_tag_set
*set
)
3138 return blk_mq_init_queue_data(set
, NULL
);
3140 EXPORT_SYMBOL(blk_mq_init_queue
);
3142 struct gendisk
*__blk_mq_alloc_disk(struct blk_mq_tag_set
*set
, void *queuedata
,
3143 struct lock_class_key
*lkclass
)
3145 struct request_queue
*q
;
3146 struct gendisk
*disk
;
3148 q
= blk_mq_init_queue_data(set
, queuedata
);
3152 disk
= __alloc_disk_node(q
, set
->numa_node
, lkclass
);
3154 blk_cleanup_queue(q
);
3155 return ERR_PTR(-ENOMEM
);
3159 EXPORT_SYMBOL(__blk_mq_alloc_disk
);
3161 static struct blk_mq_hw_ctx
*blk_mq_alloc_and_init_hctx(
3162 struct blk_mq_tag_set
*set
, struct request_queue
*q
,
3163 int hctx_idx
, int node
)
3165 struct blk_mq_hw_ctx
*hctx
= NULL
, *tmp
;
3167 /* reuse dead hctx first */
3168 spin_lock(&q
->unused_hctx_lock
);
3169 list_for_each_entry(tmp
, &q
->unused_hctx_list
, hctx_list
) {
3170 if (tmp
->numa_node
== node
) {
3176 list_del_init(&hctx
->hctx_list
);
3177 spin_unlock(&q
->unused_hctx_lock
);
3180 hctx
= blk_mq_alloc_hctx(q
, set
, node
);
3184 if (blk_mq_init_hctx(q
, set
, hctx
, hctx_idx
))
3190 kobject_put(&hctx
->kobj
);
3195 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set
*set
,
3196 struct request_queue
*q
)
3199 struct blk_mq_hw_ctx
**hctxs
= q
->queue_hw_ctx
;
3201 if (q
->nr_hw_queues
< set
->nr_hw_queues
) {
3202 struct blk_mq_hw_ctx
**new_hctxs
;
3204 new_hctxs
= kcalloc_node(set
->nr_hw_queues
,
3205 sizeof(*new_hctxs
), GFP_KERNEL
,
3210 memcpy(new_hctxs
, hctxs
, q
->nr_hw_queues
*
3212 q
->queue_hw_ctx
= new_hctxs
;
3217 /* protect against switching io scheduler */
3218 mutex_lock(&q
->sysfs_lock
);
3219 for (i
= 0; i
< set
->nr_hw_queues
; i
++) {
3221 struct blk_mq_hw_ctx
*hctx
;
3223 node
= blk_mq_hw_queue_to_node(&set
->map
[HCTX_TYPE_DEFAULT
], i
);
3225 * If the hw queue has been mapped to another numa node,
3226 * we need to realloc the hctx. If allocation fails, fallback
3227 * to use the previous one.
3229 if (hctxs
[i
] && (hctxs
[i
]->numa_node
== node
))
3232 hctx
= blk_mq_alloc_and_init_hctx(set
, q
, i
, node
);
3235 blk_mq_exit_hctx(q
, set
, hctxs
[i
], i
);
3239 pr_warn("Allocate new hctx on node %d fails,\
3240 fallback to previous one on node %d\n",
3241 node
, hctxs
[i
]->numa_node
);
3247 * Increasing nr_hw_queues fails. Free the newly allocated
3248 * hctxs and keep the previous q->nr_hw_queues.
3250 if (i
!= set
->nr_hw_queues
) {
3251 j
= q
->nr_hw_queues
;
3255 end
= q
->nr_hw_queues
;
3256 q
->nr_hw_queues
= set
->nr_hw_queues
;
3259 for (; j
< end
; j
++) {
3260 struct blk_mq_hw_ctx
*hctx
= hctxs
[j
];
3264 blk_mq_free_map_and_requests(set
, j
);
3265 blk_mq_exit_hctx(q
, set
, hctx
, j
);
3269 mutex_unlock(&q
->sysfs_lock
);
3272 int blk_mq_init_allocated_queue(struct blk_mq_tag_set
*set
,
3273 struct request_queue
*q
)
3275 /* mark the queue as mq asap */
3276 q
->mq_ops
= set
->ops
;
3278 q
->poll_cb
= blk_stat_alloc_callback(blk_mq_poll_stats_fn
,
3279 blk_mq_poll_stats_bkt
,
3280 BLK_MQ_POLL_STATS_BKTS
, q
);
3284 if (blk_mq_alloc_ctxs(q
))
3287 /* init q->mq_kobj and sw queues' kobjects */
3288 blk_mq_sysfs_init(q
);
3290 INIT_LIST_HEAD(&q
->unused_hctx_list
);
3291 spin_lock_init(&q
->unused_hctx_lock
);
3293 blk_mq_realloc_hw_ctxs(set
, q
);
3294 if (!q
->nr_hw_queues
)
3297 INIT_WORK(&q
->timeout_work
, blk_mq_timeout_work
);
3298 blk_queue_rq_timeout(q
, set
->timeout
? set
->timeout
: 30 * HZ
);
3302 q
->queue_flags
|= QUEUE_FLAG_MQ_DEFAULT
;
3303 if (set
->nr_maps
> HCTX_TYPE_POLL
&&
3304 set
->map
[HCTX_TYPE_POLL
].nr_queues
)
3305 blk_queue_flag_set(QUEUE_FLAG_POLL
, q
);
3307 INIT_DELAYED_WORK(&q
->requeue_work
, blk_mq_requeue_work
);
3308 INIT_LIST_HEAD(&q
->requeue_list
);
3309 spin_lock_init(&q
->requeue_lock
);
3311 q
->nr_requests
= set
->queue_depth
;
3314 * Default to classic polling
3316 q
->poll_nsec
= BLK_MQ_POLL_CLASSIC
;
3318 blk_mq_init_cpu_queues(q
, set
->nr_hw_queues
);
3319 blk_mq_add_queue_tag_set(set
, q
);
3320 blk_mq_map_swqueue(q
);
3324 kfree(q
->queue_hw_ctx
);
3325 q
->nr_hw_queues
= 0;
3326 blk_mq_sysfs_deinit(q
);
3328 blk_stat_free_callback(q
->poll_cb
);
3334 EXPORT_SYMBOL(blk_mq_init_allocated_queue
);
3336 /* tags can _not_ be used after returning from blk_mq_exit_queue */
3337 void blk_mq_exit_queue(struct request_queue
*q
)
3339 struct blk_mq_tag_set
*set
= q
->tag_set
;
3341 /* Checks hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED. */
3342 blk_mq_exit_hw_queues(q
, set
, set
->nr_hw_queues
);
3343 /* May clear BLK_MQ_F_TAG_QUEUE_SHARED in hctx->flags. */
3344 blk_mq_del_queue_tag_set(q
);
3347 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
3351 for (i
= 0; i
< set
->nr_hw_queues
; i
++) {
3352 if (!__blk_mq_alloc_map_and_request(set
, i
))
3361 blk_mq_free_map_and_requests(set
, i
);
3367 * Allocate the request maps associated with this tag_set. Note that this
3368 * may reduce the depth asked for, if memory is tight. set->queue_depth
3369 * will be updated to reflect the allocated depth.
3371 static int blk_mq_alloc_map_and_requests(struct blk_mq_tag_set
*set
)
3376 depth
= set
->queue_depth
;
3378 err
= __blk_mq_alloc_rq_maps(set
);
3382 set
->queue_depth
>>= 1;
3383 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
) {
3387 } while (set
->queue_depth
);
3389 if (!set
->queue_depth
|| err
) {
3390 pr_err("blk-mq: failed to allocate request map\n");
3394 if (depth
!= set
->queue_depth
)
3395 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
3396 depth
, set
->queue_depth
);
3401 static int blk_mq_update_queue_map(struct blk_mq_tag_set
*set
)
3404 * blk_mq_map_queues() and multiple .map_queues() implementations
3405 * expect that set->map[HCTX_TYPE_DEFAULT].nr_queues is set to the
3406 * number of hardware queues.
3408 if (set
->nr_maps
== 1)
3409 set
->map
[HCTX_TYPE_DEFAULT
].nr_queues
= set
->nr_hw_queues
;
3411 if (set
->ops
->map_queues
&& !is_kdump_kernel()) {
3415 * transport .map_queues is usually done in the following
3418 * for (queue = 0; queue < set->nr_hw_queues; queue++) {
3419 * mask = get_cpu_mask(queue)
3420 * for_each_cpu(cpu, mask)
3421 * set->map[x].mq_map[cpu] = queue;
3424 * When we need to remap, the table has to be cleared for
3425 * killing stale mapping since one CPU may not be mapped
3428 for (i
= 0; i
< set
->nr_maps
; i
++)
3429 blk_mq_clear_mq_map(&set
->map
[i
]);
3431 return set
->ops
->map_queues(set
);
3433 BUG_ON(set
->nr_maps
> 1);
3434 return blk_mq_map_queues(&set
->map
[HCTX_TYPE_DEFAULT
]);
3438 static int blk_mq_realloc_tag_set_tags(struct blk_mq_tag_set
*set
,
3439 int cur_nr_hw_queues
, int new_nr_hw_queues
)
3441 struct blk_mq_tags
**new_tags
;
3443 if (cur_nr_hw_queues
>= new_nr_hw_queues
)
3446 new_tags
= kcalloc_node(new_nr_hw_queues
, sizeof(struct blk_mq_tags
*),
3447 GFP_KERNEL
, set
->numa_node
);
3452 memcpy(new_tags
, set
->tags
, cur_nr_hw_queues
*
3453 sizeof(*set
->tags
));
3455 set
->tags
= new_tags
;
3456 set
->nr_hw_queues
= new_nr_hw_queues
;
3461 static int blk_mq_alloc_tag_set_tags(struct blk_mq_tag_set
*set
,
3462 int new_nr_hw_queues
)
3464 return blk_mq_realloc_tag_set_tags(set
, 0, new_nr_hw_queues
);
3468 * Alloc a tag set to be associated with one or more request queues.
3469 * May fail with EINVAL for various error conditions. May adjust the
3470 * requested depth down, if it's too large. In that case, the set
3471 * value will be stored in set->queue_depth.
3473 int blk_mq_alloc_tag_set(struct blk_mq_tag_set
*set
)
3477 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH
> 1 << BLK_MQ_UNIQUE_TAG_BITS
);
3479 if (!set
->nr_hw_queues
)
3481 if (!set
->queue_depth
)
3483 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
)
3486 if (!set
->ops
->queue_rq
)
3489 if (!set
->ops
->get_budget
^ !set
->ops
->put_budget
)
3492 if (set
->queue_depth
> BLK_MQ_MAX_DEPTH
) {
3493 pr_info("blk-mq: reduced tag depth to %u\n",
3495 set
->queue_depth
= BLK_MQ_MAX_DEPTH
;
3500 else if (set
->nr_maps
> HCTX_MAX_TYPES
)
3504 * If a crashdump is active, then we are potentially in a very
3505 * memory constrained environment. Limit us to 1 queue and
3506 * 64 tags to prevent using too much memory.
3508 if (is_kdump_kernel()) {
3509 set
->nr_hw_queues
= 1;
3511 set
->queue_depth
= min(64U, set
->queue_depth
);
3514 * There is no use for more h/w queues than cpus if we just have
3517 if (set
->nr_maps
== 1 && set
->nr_hw_queues
> nr_cpu_ids
)
3518 set
->nr_hw_queues
= nr_cpu_ids
;
3520 if (blk_mq_alloc_tag_set_tags(set
, set
->nr_hw_queues
) < 0)
3524 for (i
= 0; i
< set
->nr_maps
; i
++) {
3525 set
->map
[i
].mq_map
= kcalloc_node(nr_cpu_ids
,
3526 sizeof(set
->map
[i
].mq_map
[0]),
3527 GFP_KERNEL
, set
->numa_node
);
3528 if (!set
->map
[i
].mq_map
)
3529 goto out_free_mq_map
;
3530 set
->map
[i
].nr_queues
= is_kdump_kernel() ? 1 : set
->nr_hw_queues
;
3533 ret
= blk_mq_update_queue_map(set
);
3535 goto out_free_mq_map
;
3537 ret
= blk_mq_alloc_map_and_requests(set
);
3539 goto out_free_mq_map
;
3541 if (blk_mq_is_sbitmap_shared(set
->flags
)) {
3542 atomic_set(&set
->active_queues_shared_sbitmap
, 0);
3544 if (blk_mq_init_shared_sbitmap(set
)) {
3546 goto out_free_mq_rq_maps
;
3550 mutex_init(&set
->tag_list_lock
);
3551 INIT_LIST_HEAD(&set
->tag_list
);
3555 out_free_mq_rq_maps
:
3556 for (i
= 0; i
< set
->nr_hw_queues
; i
++)
3557 blk_mq_free_map_and_requests(set
, i
);
3559 for (i
= 0; i
< set
->nr_maps
; i
++) {
3560 kfree(set
->map
[i
].mq_map
);
3561 set
->map
[i
].mq_map
= NULL
;
3567 EXPORT_SYMBOL(blk_mq_alloc_tag_set
);
3569 /* allocate and initialize a tagset for a simple single-queue device */
3570 int blk_mq_alloc_sq_tag_set(struct blk_mq_tag_set
*set
,
3571 const struct blk_mq_ops
*ops
, unsigned int queue_depth
,
3572 unsigned int set_flags
)
3574 memset(set
, 0, sizeof(*set
));
3576 set
->nr_hw_queues
= 1;
3578 set
->queue_depth
= queue_depth
;
3579 set
->numa_node
= NUMA_NO_NODE
;
3580 set
->flags
= set_flags
;
3581 return blk_mq_alloc_tag_set(set
);
3583 EXPORT_SYMBOL_GPL(blk_mq_alloc_sq_tag_set
);
3585 void blk_mq_free_tag_set(struct blk_mq_tag_set
*set
)
3589 for (i
= 0; i
< set
->nr_hw_queues
; i
++)
3590 blk_mq_free_map_and_requests(set
, i
);
3592 if (blk_mq_is_sbitmap_shared(set
->flags
))
3593 blk_mq_exit_shared_sbitmap(set
);
3595 for (j
= 0; j
< set
->nr_maps
; j
++) {
3596 kfree(set
->map
[j
].mq_map
);
3597 set
->map
[j
].mq_map
= NULL
;
3603 EXPORT_SYMBOL(blk_mq_free_tag_set
);
3605 int blk_mq_update_nr_requests(struct request_queue
*q
, unsigned int nr
)
3607 struct blk_mq_tag_set
*set
= q
->tag_set
;
3608 struct blk_mq_hw_ctx
*hctx
;
3614 if (q
->nr_requests
== nr
)
3617 blk_mq_freeze_queue(q
);
3618 blk_mq_quiesce_queue(q
);
3621 queue_for_each_hw_ctx(q
, hctx
, i
) {
3625 * If we're using an MQ scheduler, just update the scheduler
3626 * queue depth. This is similar to what the old code would do.
3628 if (!hctx
->sched_tags
) {
3629 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->tags
, nr
,
3631 if (!ret
&& blk_mq_is_sbitmap_shared(set
->flags
))
3632 blk_mq_tag_resize_shared_sbitmap(set
, nr
);
3634 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->sched_tags
,
3636 if (blk_mq_is_sbitmap_shared(set
->flags
)) {
3637 hctx
->sched_tags
->bitmap_tags
=
3638 &q
->sched_bitmap_tags
;
3639 hctx
->sched_tags
->breserved_tags
=
3640 &q
->sched_breserved_tags
;
3645 if (q
->elevator
&& q
->elevator
->type
->ops
.depth_updated
)
3646 q
->elevator
->type
->ops
.depth_updated(hctx
);
3649 q
->nr_requests
= nr
;
3650 if (q
->elevator
&& blk_mq_is_sbitmap_shared(set
->flags
))
3651 sbitmap_queue_resize(&q
->sched_bitmap_tags
,
3652 nr
- set
->reserved_tags
);
3655 blk_mq_unquiesce_queue(q
);
3656 blk_mq_unfreeze_queue(q
);
3662 * request_queue and elevator_type pair.
3663 * It is just used by __blk_mq_update_nr_hw_queues to cache
3664 * the elevator_type associated with a request_queue.
3666 struct blk_mq_qe_pair
{
3667 struct list_head node
;
3668 struct request_queue
*q
;
3669 struct elevator_type
*type
;
3673 * Cache the elevator_type in qe pair list and switch the
3674 * io scheduler to 'none'
3676 static bool blk_mq_elv_switch_none(struct list_head
*head
,
3677 struct request_queue
*q
)
3679 struct blk_mq_qe_pair
*qe
;
3684 qe
= kmalloc(sizeof(*qe
), GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
);
3688 INIT_LIST_HEAD(&qe
->node
);
3690 qe
->type
= q
->elevator
->type
;
3691 list_add(&qe
->node
, head
);
3693 mutex_lock(&q
->sysfs_lock
);
3695 * After elevator_switch_mq, the previous elevator_queue will be
3696 * released by elevator_release. The reference of the io scheduler
3697 * module get by elevator_get will also be put. So we need to get
3698 * a reference of the io scheduler module here to prevent it to be
3701 __module_get(qe
->type
->elevator_owner
);
3702 elevator_switch_mq(q
, NULL
);
3703 mutex_unlock(&q
->sysfs_lock
);
3708 static void blk_mq_elv_switch_back(struct list_head
*head
,
3709 struct request_queue
*q
)
3711 struct blk_mq_qe_pair
*qe
;
3712 struct elevator_type
*t
= NULL
;
3714 list_for_each_entry(qe
, head
, node
)
3723 list_del(&qe
->node
);
3726 mutex_lock(&q
->sysfs_lock
);
3727 elevator_switch_mq(q
, t
);
3728 mutex_unlock(&q
->sysfs_lock
);
3731 static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
,
3734 struct request_queue
*q
;
3736 int prev_nr_hw_queues
;
3738 lockdep_assert_held(&set
->tag_list_lock
);
3740 if (set
->nr_maps
== 1 && nr_hw_queues
> nr_cpu_ids
)
3741 nr_hw_queues
= nr_cpu_ids
;
3742 if (nr_hw_queues
< 1)
3744 if (set
->nr_maps
== 1 && nr_hw_queues
== set
->nr_hw_queues
)
3747 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
3748 blk_mq_freeze_queue(q
);
3750 * Switch IO scheduler to 'none', cleaning up the data associated
3751 * with the previous scheduler. We will switch back once we are done
3752 * updating the new sw to hw queue mappings.
3754 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
3755 if (!blk_mq_elv_switch_none(&head
, q
))
3758 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
3759 blk_mq_debugfs_unregister_hctxs(q
);
3760 blk_mq_sysfs_unregister(q
);
3763 prev_nr_hw_queues
= set
->nr_hw_queues
;
3764 if (blk_mq_realloc_tag_set_tags(set
, set
->nr_hw_queues
, nr_hw_queues
) <
3768 set
->nr_hw_queues
= nr_hw_queues
;
3770 blk_mq_update_queue_map(set
);
3771 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
3772 blk_mq_realloc_hw_ctxs(set
, q
);
3773 if (q
->nr_hw_queues
!= set
->nr_hw_queues
) {
3774 pr_warn("Increasing nr_hw_queues to %d fails, fallback to %d\n",
3775 nr_hw_queues
, prev_nr_hw_queues
);
3776 set
->nr_hw_queues
= prev_nr_hw_queues
;
3777 blk_mq_map_queues(&set
->map
[HCTX_TYPE_DEFAULT
]);
3780 blk_mq_map_swqueue(q
);
3784 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
3785 blk_mq_sysfs_register(q
);
3786 blk_mq_debugfs_register_hctxs(q
);
3790 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
3791 blk_mq_elv_switch_back(&head
, q
);
3793 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
3794 blk_mq_unfreeze_queue(q
);
3797 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
, int nr_hw_queues
)
3799 mutex_lock(&set
->tag_list_lock
);
3800 __blk_mq_update_nr_hw_queues(set
, nr_hw_queues
);
3801 mutex_unlock(&set
->tag_list_lock
);
3803 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues
);
3805 /* Enable polling stats and return whether they were already enabled. */
3806 static bool blk_poll_stats_enable(struct request_queue
*q
)
3808 if (test_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
) ||
3809 blk_queue_flag_test_and_set(QUEUE_FLAG_POLL_STATS
, q
))
3811 blk_stat_add_callback(q
, q
->poll_cb
);
3815 static void blk_mq_poll_stats_start(struct request_queue
*q
)
3818 * We don't arm the callback if polling stats are not enabled or the
3819 * callback is already active.
3821 if (!test_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
) ||
3822 blk_stat_is_active(q
->poll_cb
))
3825 blk_stat_activate_msecs(q
->poll_cb
, 100);
3828 static void blk_mq_poll_stats_fn(struct blk_stat_callback
*cb
)
3830 struct request_queue
*q
= cb
->data
;
3833 for (bucket
= 0; bucket
< BLK_MQ_POLL_STATS_BKTS
; bucket
++) {
3834 if (cb
->stat
[bucket
].nr_samples
)
3835 q
->poll_stat
[bucket
] = cb
->stat
[bucket
];
3839 static unsigned long blk_mq_poll_nsecs(struct request_queue
*q
,
3842 unsigned long ret
= 0;
3846 * If stats collection isn't on, don't sleep but turn it on for
3849 if (!blk_poll_stats_enable(q
))
3853 * As an optimistic guess, use half of the mean service time
3854 * for this type of request. We can (and should) make this smarter.
3855 * For instance, if the completion latencies are tight, we can
3856 * get closer than just half the mean. This is especially
3857 * important on devices where the completion latencies are longer
3858 * than ~10 usec. We do use the stats for the relevant IO size
3859 * if available which does lead to better estimates.
3861 bucket
= blk_mq_poll_stats_bkt(rq
);
3865 if (q
->poll_stat
[bucket
].nr_samples
)
3866 ret
= (q
->poll_stat
[bucket
].mean
+ 1) / 2;
3871 static bool blk_mq_poll_hybrid_sleep(struct request_queue
*q
,
3874 struct hrtimer_sleeper hs
;
3875 enum hrtimer_mode mode
;
3879 if (rq
->rq_flags
& RQF_MQ_POLL_SLEPT
)
3883 * If we get here, hybrid polling is enabled. Hence poll_nsec can be:
3885 * 0: use half of prev avg
3886 * >0: use this specific value
3888 if (q
->poll_nsec
> 0)
3889 nsecs
= q
->poll_nsec
;
3891 nsecs
= blk_mq_poll_nsecs(q
, rq
);
3896 rq
->rq_flags
|= RQF_MQ_POLL_SLEPT
;
3899 * This will be replaced with the stats tracking code, using
3900 * 'avg_completion_time / 2' as the pre-sleep target.
3904 mode
= HRTIMER_MODE_REL
;
3905 hrtimer_init_sleeper_on_stack(&hs
, CLOCK_MONOTONIC
, mode
);
3906 hrtimer_set_expires(&hs
.timer
, kt
);
3909 if (blk_mq_rq_state(rq
) == MQ_RQ_COMPLETE
)
3911 set_current_state(TASK_UNINTERRUPTIBLE
);
3912 hrtimer_sleeper_start_expires(&hs
, mode
);
3915 hrtimer_cancel(&hs
.timer
);
3916 mode
= HRTIMER_MODE_ABS
;
3917 } while (hs
.task
&& !signal_pending(current
));
3919 __set_current_state(TASK_RUNNING
);
3920 destroy_hrtimer_on_stack(&hs
.timer
);
3924 static bool blk_mq_poll_hybrid(struct request_queue
*q
,
3925 struct blk_mq_hw_ctx
*hctx
, blk_qc_t cookie
)
3929 if (q
->poll_nsec
== BLK_MQ_POLL_CLASSIC
)
3932 if (!blk_qc_t_is_internal(cookie
))
3933 rq
= blk_mq_tag_to_rq(hctx
->tags
, blk_qc_t_to_tag(cookie
));
3935 rq
= blk_mq_tag_to_rq(hctx
->sched_tags
, blk_qc_t_to_tag(cookie
));
3937 * With scheduling, if the request has completed, we'll
3938 * get a NULL return here, as we clear the sched tag when
3939 * that happens. The request still remains valid, like always,
3940 * so we should be safe with just the NULL check.
3946 return blk_mq_poll_hybrid_sleep(q
, rq
);
3950 * blk_poll - poll for IO completions
3952 * @cookie: cookie passed back at IO submission time
3953 * @spin: whether to spin for completions
3956 * Poll for completions on the passed in queue. Returns number of
3957 * completed entries found. If @spin is true, then blk_poll will continue
3958 * looping until at least one completion is found, unless the task is
3959 * otherwise marked running (or we need to reschedule).
3961 int blk_poll(struct request_queue
*q
, blk_qc_t cookie
, bool spin
)
3963 struct blk_mq_hw_ctx
*hctx
;
3966 if (!blk_qc_t_valid(cookie
) ||
3967 !test_bit(QUEUE_FLAG_POLL
, &q
->queue_flags
))
3971 blk_flush_plug_list(current
->plug
, false);
3973 hctx
= q
->queue_hw_ctx
[blk_qc_t_to_queue_num(cookie
)];
3976 * If we sleep, have the caller restart the poll loop to reset
3977 * the state. Like for the other success return cases, the
3978 * caller is responsible for checking if the IO completed. If
3979 * the IO isn't complete, we'll get called again and will go
3980 * straight to the busy poll loop. If specified not to spin,
3981 * we also should not sleep.
3983 if (spin
&& blk_mq_poll_hybrid(q
, hctx
, cookie
))
3986 hctx
->poll_considered
++;
3988 state
= get_current_state();
3992 hctx
->poll_invoked
++;
3994 ret
= q
->mq_ops
->poll(hctx
);
3996 hctx
->poll_success
++;
3997 __set_current_state(TASK_RUNNING
);
4001 if (signal_pending_state(state
, current
))
4002 __set_current_state(TASK_RUNNING
);
4004 if (task_is_running(current
))
4006 if (ret
< 0 || !spin
)
4009 } while (!need_resched());
4011 __set_current_state(TASK_RUNNING
);
4014 EXPORT_SYMBOL_GPL(blk_poll
);
4016 unsigned int blk_mq_rq_cpu(struct request
*rq
)
4018 return rq
->mq_ctx
->cpu
;
4020 EXPORT_SYMBOL(blk_mq_rq_cpu
);
4022 void blk_mq_cancel_work_sync(struct request_queue
*q
)
4024 if (queue_is_mq(q
)) {
4025 struct blk_mq_hw_ctx
*hctx
;
4028 cancel_delayed_work_sync(&q
->requeue_work
);
4030 queue_for_each_hw_ctx(q
, hctx
, i
)
4031 cancel_delayed_work_sync(&hctx
->run_work
);
4035 static int __init
blk_mq_init(void)
4039 for_each_possible_cpu(i
)
4040 init_llist_head(&per_cpu(blk_cpu_done
, i
));
4041 open_softirq(BLOCK_SOFTIRQ
, blk_done_softirq
);
4043 cpuhp_setup_state_nocalls(CPUHP_BLOCK_SOFTIRQ_DEAD
,
4044 "block/softirq:dead", NULL
,
4045 blk_softirq_cpu_dead
);
4046 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD
, "block/mq:dead", NULL
,
4047 blk_mq_hctx_notify_dead
);
4048 cpuhp_setup_state_multi(CPUHP_AP_BLK_MQ_ONLINE
, "block/mq:online",
4049 blk_mq_hctx_notify_online
,
4050 blk_mq_hctx_notify_offline
);
4053 subsys_initcall(blk_mq_init
);