Repository navigation
Expand file tree
/
Copy pathblk-mq.c
More file actions
2898 lines (2396 loc) · 70.1 KB
/
Copy pathblk-mq.c
File metadata and controls
2898 lines (2396 loc) · 70.1 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
/*
* Block multiqueue core code
*
* Copyright (C) 2013-2014 Jens Axboe
* Copyright (C) 2013-2014 Christoph Hellwig
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/backing-dev.h>
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/kmemleak.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
#include <linux/smp.h>
#include <linux/llist.h>
#include <linux/list_sort.h>
#include <linux/cpu.h>
#include <linux/cache.h>
#include <linux/sched/sysctl.h>
#include <linux/sched/topology.h>
#include <linux/sched/signal.h>
#include <linux/delay.h>
#include <linux/crash_dump.h>
#include <linux/prefetch.h>
#include <trace/events/block.h>
#include <linux/blk-mq.h>
#include "blk.h"
#include "blk-mq.h"
#include "blk-mq-tag.h"
#include "blk-stat.h"
#include "blk-wbt.h"
#include "blk-mq-sched.h"
static DEFINE_MUTEX(all_q_mutex);
static LIST_HEAD(all_q_list);
static void blk_mq_poll_stats_start(struct request_queue *q);
static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb);
static int blk_mq_poll_stats_bkt(const struct request *rq)
{
int ddir, bytes, bucket;
ddir = rq_data_dir(rq);
bytes = blk_rq_bytes(rq);
bucket = ddir + 2*(ilog2(bytes) - 9);
if (bucket < 0)
return -1;
else if (bucket >= BLK_MQ_POLL_STATS_BKTS)
return ddir + BLK_MQ_POLL_STATS_BKTS - 2;
return bucket;
}
/*
* Check if any of the ctx's have pending work in this hardware queue
*/
bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx)
{
return sbitmap_any_bit_set(&hctx->ctx_map) ||
!list_empty_careful(&hctx->dispatch) ||
blk_mq_sched_has_work(hctx);
}
/*
* Mark this ctx as having pending work in this hardware queue
*/
static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx *hctx,
struct blk_mq_ctx *ctx)
{
if (!sbitmap_test_bit(&hctx->ctx_map, ctx->index_hw))
sbitmap_set_bit(&hctx->ctx_map, ctx->index_hw);
}
static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,
struct blk_mq_ctx *ctx)
{
sbitmap_clear_bit(&hctx->ctx_map, ctx->index_hw);
}
void blk_freeze_queue_start(struct request_queue *q)
{
int freeze_depth;
freeze_depth = atomic_inc_return(&q->mq_freeze_depth);
if (freeze_depth == 1) {
percpu_ref_kill(&q->q_usage_counter);
blk_mq_run_hw_queues(q, false);
}
}
EXPORT_SYMBOL_GPL(blk_freeze_queue_start);
void blk_mq_freeze_queue_wait(struct request_queue *q)
{
wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->q_usage_counter));
}
EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait);
int blk_mq_freeze_queue_wait_timeout(struct request_queue *q,
unsigned long timeout)
{
return wait_event_timeout(q->mq_freeze_wq,
percpu_ref_is_zero(&q->q_usage_counter),
timeout);
}
EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout);
/*
* Guarantee no request is in use, so we can change any data structure of
* the queue afterward.
*/
void blk_freeze_queue(struct request_queue *q)
{
/*
* In the !blk_mq case we are only calling this to kill the
* q_usage_counter, otherwise this increases the freeze depth
* and waits for it to return to zero. For this reason there is
* no blk_unfreeze_queue(), and blk_freeze_queue() is not
* exported to drivers as the only user for unfreeze is blk_mq.
*/
blk_freeze_queue_start(q);
blk_mq_freeze_queue_wait(q);
}
void blk_mq_freeze_queue(struct request_queue *q)
{
/*
* ...just an alias to keep freeze and unfreeze actions balanced
* in the blk_mq_* namespace
*/
blk_freeze_queue(q);
}
EXPORT_SYMBOL_GPL(blk_mq_freeze_queue);
void blk_mq_unfreeze_queue(struct request_queue *q)
{
int freeze_depth;
freeze_depth = atomic_dec_return(&q->mq_freeze_depth);
WARN_ON_ONCE(freeze_depth < 0);
if (!freeze_depth) {
percpu_ref_reinit(&q->q_usage_counter);
wake_up_all(&q->mq_freeze_wq);
}
}
EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue);
/**
* blk_mq_quiesce_queue() - wait until all ongoing queue_rq calls have finished
* @q: request queue.
*
* Note: this function does not prevent that the struct request end_io()
* callback function is invoked. Additionally, it is not prevented that
* new queue_rq() calls occur unless the queue has been stopped first.
*/
void blk_mq_quiesce_queue(struct request_queue *q)
{
struct blk_mq_hw_ctx *hctx;
unsigned int i;
bool rcu = false;
blk_mq_stop_hw_queues(q);
queue_for_each_hw_ctx(q, hctx, i) {
if (hctx->flags & BLK_MQ_F_BLOCKING)
synchronize_srcu(&hctx->queue_rq_srcu);
else
rcu = true;
}
if (rcu)
synchronize_rcu();
}
EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue);
void blk_mq_wake_waiters(struct request_queue *q)
{
struct blk_mq_hw_ctx *hctx;
unsigned int i;
queue_for_each_hw_ctx(q, hctx, i)
if (blk_mq_hw_queue_mapped(hctx))
blk_mq_tag_wakeup_all(hctx->tags, true);
/*
* If we are called because the queue has now been marked as
* dying, we need to ensure that processes currently waiting on
* the queue are notified as well.
*/
wake_up_all(&q->mq_freeze_wq);
}
bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx)
{
return blk_mq_has_free_tags(hctx->tags);
}
EXPORT_SYMBOL(blk_mq_can_queue);
void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx,
struct request *rq, unsigned int op)
{
INIT_LIST_HEAD(&rq->queuelist);
/* csd/requeue_work/fifo_time is initialized before use */
rq->q = q;
rq->mq_ctx = ctx;
rq->cmd_flags = op;
if (blk_queue_io_stat(q))
rq->rq_flags |= RQF_IO_STAT;
/* do not touch atomic flags, it needs atomic ops against the timer */
rq->cpu = -1;
INIT_HLIST_NODE(&rq->hash);
RB_CLEAR_NODE(&rq->rb_node);
rq->rq_disk = NULL;
rq->part = NULL;
rq->start_time = jiffies;
#ifdef CONFIG_BLK_CGROUP
rq->rl = NULL;
set_start_time_ns(rq);
rq->io_start_time_ns = 0;
#endif
rq->nr_phys_segments = 0;
#if defined(CONFIG_BLK_DEV_INTEGRITY)
rq->nr_integrity_segments = 0;
#endif
rq->special = NULL;
/* tag was already set */
rq->extra_len = 0;
INIT_LIST_HEAD(&rq->timeout_list);
rq->timeout = 0;
rq->end_io = NULL;
rq->end_io_data = NULL;
rq->next_rq = NULL;
ctx->rq_dispatched[op_is_sync(op)]++;
}
EXPORT_SYMBOL_GPL(blk_mq_rq_ctx_init);
struct request *__blk_mq_alloc_request(struct blk_mq_alloc_data *data,
unsigned int op)
{
struct request *rq;
unsigned int tag;
tag = blk_mq_get_tag(data);
if (tag != BLK_MQ_TAG_FAIL) {
struct blk_mq_tags *tags = blk_mq_tags_from_data(data);
rq = tags->static_rqs[tag];
if (data->flags & BLK_MQ_REQ_INTERNAL) {
rq->tag = -1;
rq->internal_tag = tag;
} else {
if (blk_mq_tag_busy(data->hctx)) {
rq->rq_flags = RQF_MQ_INFLIGHT;
atomic_inc(&data->hctx->nr_active);
}
rq->tag = tag;
rq->internal_tag = -1;
data->hctx->tags->rqs[rq->tag] = rq;
}
blk_mq_rq_ctx_init(data->q, data->ctx, rq, op);
return rq;
}
return NULL;
}
EXPORT_SYMBOL_GPL(__blk_mq_alloc_request);
struct request *blk_mq_alloc_request(struct request_queue *q, int rw,
unsigned int flags)
{
struct blk_mq_alloc_data alloc_data = { .flags = flags };
struct request *rq;
int ret;
ret = blk_queue_enter(q, flags & BLK_MQ_REQ_NOWAIT);
if (ret)
return ERR_PTR(ret);
rq = blk_mq_sched_get_request(q, NULL, rw, &alloc_data);
blk_mq_put_ctx(alloc_data.ctx);
blk_queue_exit(q);
if (!rq)
return ERR_PTR(-EWOULDBLOCK);
rq->__data_len = 0;
rq->__sector = (sector_t) -1;
rq->bio = rq->biotail = NULL;
return rq;
}
EXPORT_SYMBOL(blk_mq_alloc_request);
struct request *blk_mq_alloc_request_hctx(struct request_queue *q, int rw,
unsigned int flags, unsigned int hctx_idx)
{
struct blk_mq_alloc_data alloc_data = { .flags = flags };
struct request *rq;
unsigned int cpu;
int ret;
/*
* If the tag allocator sleeps we could get an allocation for a
* different hardware context. No need to complicate the low level
* allocator for this for the rare use case of a command tied to
* a specific queue.
*/
if (WARN_ON_ONCE(!(flags & BLK_MQ_REQ_NOWAIT)))
return ERR_PTR(-EINVAL);
if (hctx_idx >= q->nr_hw_queues)
return ERR_PTR(-EIO);
ret = blk_queue_enter(q, true);
if (ret)
return ERR_PTR(ret);
/*
* Check if the hardware context is actually mapped to anything.
* If not tell the caller that it should skip this queue.
*/
alloc_data.hctx = q->queue_hw_ctx[hctx_idx];
if (!blk_mq_hw_queue_mapped(alloc_data.hctx)) {
blk_queue_exit(q);
return ERR_PTR(-EXDEV);
}
cpu = cpumask_first(alloc_data.hctx->cpumask);
alloc_data.ctx = __blk_mq_get_ctx(q, cpu);
rq = blk_mq_sched_get_request(q, NULL, rw, &alloc_data);
blk_queue_exit(q);
if (!rq)
return ERR_PTR(-EWOULDBLOCK);
return rq;
}
EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx);
void __blk_mq_finish_request(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
struct request *rq)
{
const int sched_tag = rq->internal_tag;
struct request_queue *q = rq->q;
if (rq->rq_flags & RQF_MQ_INFLIGHT)
atomic_dec(&hctx->nr_active);
wbt_done(q->rq_wb, &rq->issue_stat);
rq->rq_flags = 0;
clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
clear_bit(REQ_ATOM_POLL_SLEPT, &rq->atomic_flags);
if (rq->tag != -1)
blk_mq_put_tag(hctx, hctx->tags, ctx, rq->tag);
if (sched_tag != -1)
blk_mq_put_tag(hctx, hctx->sched_tags, ctx, sched_tag);
blk_mq_sched_restart(hctx);
blk_queue_exit(q);
}
static void blk_mq_finish_hctx_request(struct blk_mq_hw_ctx *hctx,
struct request *rq)
{
struct blk_mq_ctx *ctx = rq->mq_ctx;
ctx->rq_completed[rq_is_sync(rq)]++;
__blk_mq_finish_request(hctx, ctx, rq);
}
void blk_mq_finish_request(struct request *rq)
{
blk_mq_finish_hctx_request(blk_mq_map_queue(rq->q, rq->mq_ctx->cpu), rq);
}
EXPORT_SYMBOL_GPL(blk_mq_finish_request);
void blk_mq_free_request(struct request *rq)
{
blk_mq_sched_put_request(rq);
}
EXPORT_SYMBOL_GPL(blk_mq_free_request);
inline void __blk_mq_end_request(struct request *rq, int error)
{
blk_account_io_done(rq);
if (rq->end_io) {
wbt_done(rq->q->rq_wb, &rq->issue_stat);
rq->end_io(rq, error);
} else {
if (unlikely(blk_bidi_rq(rq)))
blk_mq_free_request(rq->next_rq);
blk_mq_free_request(rq);
}
}
EXPORT_SYMBOL(__blk_mq_end_request);
void blk_mq_end_request(struct request *rq, int error)
{
if (blk_update_request(rq, error, blk_rq_bytes(rq)))
BUG();
__blk_mq_end_request(rq, error);
}
EXPORT_SYMBOL(blk_mq_end_request);
static void __blk_mq_complete_request_remote(void *data)
{
struct request *rq = data;
rq->q->softirq_done_fn(rq);
}
static void __blk_mq_complete_request(struct request *rq)
{
struct blk_mq_ctx *ctx = rq->mq_ctx;
bool shared = false;
int cpu;
if (rq->internal_tag != -1)
blk_mq_sched_completed_request(rq);
if (rq->rq_flags & RQF_STATS) {
blk_mq_poll_stats_start(rq->q);
blk_stat_add(rq);
}
if (!test_bit(QUEUE_FLAG_SAME_COMP, &rq->q->queue_flags)) {
rq->q->softirq_done_fn(rq);
return;
}
cpu = get_cpu();
if (!test_bit(QUEUE_FLAG_SAME_FORCE, &rq->q->queue_flags))
shared = cpus_share_cache(cpu, ctx->cpu);
if (cpu != ctx->cpu && !shared && cpu_online(ctx->cpu)) {
rq->csd.func = __blk_mq_complete_request_remote;
rq->csd.info = rq;
rq->csd.flags = 0;
smp_call_function_single_async(ctx->cpu, &rq->csd);
} else {
rq->q->softirq_done_fn(rq);
}
put_cpu();
}
/**
* blk_mq_complete_request - end I/O on a request
* @rq: the request being processed
*
* Description:
* Ends all I/O on a request. It does not handle partial completions.
* The actual completion happens out-of-order, through a IPI handler.
**/
void blk_mq_complete_request(struct request *rq)
{
struct request_queue *q = rq->q;
if (unlikely(blk_should_fake_timeout(q)))
return;
if (!blk_mark_rq_complete(rq))
__blk_mq_complete_request(rq);
}
EXPORT_SYMBOL(blk_mq_complete_request);
int blk_mq_request_started(struct request *rq)
{
return test_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
}
EXPORT_SYMBOL_GPL(blk_mq_request_started);
void blk_mq_start_request(struct request *rq)
{
struct request_queue *q = rq->q;
blk_mq_sched_started_request(rq);
trace_block_rq_issue(q, rq);
if (test_bit(QUEUE_FLAG_STATS, &q->queue_flags)) {
blk_stat_set_issue(&rq->issue_stat, blk_rq_sectors(rq));
rq->rq_flags |= RQF_STATS;
wbt_issue(q->rq_wb, &rq->issue_stat);
}
blk_add_timer(rq);
/*
* Ensure that ->deadline is visible before set the started
* flag and clear the completed flag.
*/
smp_mb__before_atomic();
/*
* Mark us as started and clear complete. Complete might have been
* set if requeue raced with timeout, which then marked it as
* complete. So be sure to clear complete again when we start
* the request, otherwise we'll ignore the completion event.
*/
if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
set_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
if (test_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags))
clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
if (q->dma_drain_size && blk_rq_bytes(rq)) {
/*
* Make sure space for the drain appears. We know we can do
* this because max_hw_segments has been adjusted to be one
* fewer than the device can handle.
*/
rq->nr_phys_segments++;
}
}
EXPORT_SYMBOL(blk_mq_start_request);
/*
* When we reach here because queue is busy, REQ_ATOM_COMPLETE
* flag isn't set yet, so there may be race with timeout handler,
* but given rq->deadline is just set in .queue_rq() under
* this situation, the race won't be possible in reality because
* rq->timeout should be set as big enough to cover the window
* between blk_mq_start_request() called from .queue_rq() and
* clearing REQ_ATOM_STARTED here.
*/
static void __blk_mq_requeue_request(struct request *rq)
{
struct request_queue *q = rq->q;
trace_block_rq_requeue(q, rq);
wbt_requeue(q->rq_wb, &rq->issue_stat);
blk_mq_sched_requeue_request(rq);
if (test_and_clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) {
if (q->dma_drain_size && blk_rq_bytes(rq))
rq->nr_phys_segments--;
}
}
void blk_mq_requeue_request(struct request *rq, bool kick_requeue_list)
{
__blk_mq_requeue_request(rq);
BUG_ON(blk_queued_rq(rq));
blk_mq_add_to_requeue_list(rq, true, kick_requeue_list);
}
EXPORT_SYMBOL(blk_mq_requeue_request);
static void blk_mq_requeue_work(struct work_struct *work)
{
struct request_queue *q =
container_of(work, struct request_queue, requeue_work.work);
LIST_HEAD(rq_list);
struct request *rq, *next;
unsigned long flags;
spin_lock_irqsave(&q->requeue_lock, flags);
list_splice_init(&q->requeue_list, &rq_list);
spin_unlock_irqrestore(&q->requeue_lock, flags);
list_for_each_entry_safe(rq, next, &rq_list, queuelist) {
if (!(rq->rq_flags & RQF_SOFTBARRIER))
continue;
rq->rq_flags &= ~RQF_SOFTBARRIER;
list_del_init(&rq->queuelist);
blk_mq_sched_insert_request(rq, true, false, false, true);
}
while (!list_empty(&rq_list)) {
rq = list_entry(rq_list.next, struct request, queuelist);
list_del_init(&rq->queuelist);
blk_mq_sched_insert_request(rq, false, false, false, true);
}
blk_mq_run_hw_queues(q, false);
}
void blk_mq_add_to_requeue_list(struct request *rq, bool at_head,
bool kick_requeue_list)
{
struct request_queue *q = rq->q;
unsigned long flags;
/*
* We abuse this flag that is otherwise used by the I/O scheduler to
* request head insertation from the workqueue.
*/
BUG_ON(rq->rq_flags & RQF_SOFTBARRIER);
spin_lock_irqsave(&q->requeue_lock, flags);
if (at_head) {
rq->rq_flags |= RQF_SOFTBARRIER;
list_add(&rq->queuelist, &q->requeue_list);
} else {
list_add_tail(&rq->queuelist, &q->requeue_list);
}
spin_unlock_irqrestore(&q->requeue_lock, flags);
if (kick_requeue_list)
blk_mq_kick_requeue_list(q);
}
EXPORT_SYMBOL(blk_mq_add_to_requeue_list);
void blk_mq_kick_requeue_list(struct request_queue *q)
{
kblockd_schedule_delayed_work(&q->requeue_work, 0);
}
EXPORT_SYMBOL(blk_mq_kick_requeue_list);
void blk_mq_delay_kick_requeue_list(struct request_queue *q,
unsigned long msecs)
{
kblockd_schedule_delayed_work(&q->requeue_work,
msecs_to_jiffies(msecs));
}
EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list);
void blk_mq_abort_requeue_list(struct request_queue *q)
{
unsigned long flags;
LIST_HEAD(rq_list);
spin_lock_irqsave(&q->requeue_lock, flags);
list_splice_init(&q->requeue_list, &rq_list);
spin_unlock_irqrestore(&q->requeue_lock, flags);
while (!list_empty(&rq_list)) {
struct request *rq;
rq = list_first_entry(&rq_list, struct request, queuelist);
list_del_init(&rq->queuelist);
blk_mq_end_request(rq, -EIO);
}
}
EXPORT_SYMBOL(blk_mq_abort_requeue_list);
struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
{
if (tag < tags->nr_tags) {
prefetch(tags->rqs[tag]);
return tags->rqs[tag];
}
return NULL;
}
EXPORT_SYMBOL(blk_mq_tag_to_rq);
struct blk_mq_timeout_data {
unsigned long next;
unsigned int next_set;
};
void blk_mq_rq_timed_out(struct request *req, bool reserved)
{
const struct blk_mq_ops *ops = req->q->mq_ops;
enum blk_eh_timer_return ret = BLK_EH_RESET_TIMER;
/*
* We know that complete is set at this point. If STARTED isn't set
* anymore, then the request isn't active and the "timeout" should
* just be ignored. This can happen due to the bitflag ordering.
* Timeout first checks if STARTED is set, and if it is, assumes
* the request is active. But if we race with completion, then
* both flags will get cleared. So check here again, and ignore
* a timeout event with a request that isn't active.
*/
if (!test_bit(REQ_ATOM_STARTED, &req->atomic_flags))
return;
if (ops->timeout)
ret = ops->timeout(req, reserved);
switch (ret) {
case BLK_EH_HANDLED:
__blk_mq_complete_request(req);
break;
case BLK_EH_RESET_TIMER:
blk_add_timer(req);
blk_clear_rq_complete(req);
break;
case BLK_EH_NOT_HANDLED:
break;
default:
printk(KERN_ERR "block: bad eh return: %d\n", ret);
break;
}
}
static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
struct request *rq, void *priv, bool reserved)
{
struct blk_mq_timeout_data *data = priv;
if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
return;
/*
* The rq being checked may have been freed and reallocated
* out already here, we avoid this race by checking rq->deadline
* and REQ_ATOM_COMPLETE flag together:
*
* - if rq->deadline is observed as new value because of
* reusing, the rq won't be timed out because of timing.
* - if rq->deadline is observed as previous value,
* REQ_ATOM_COMPLETE flag won't be cleared in reuse path
* because we put a barrier between setting rq->deadline
* and clearing the flag in blk_mq_start_request(), so
* this rq won't be timed out too.
*/
if (time_after_eq(jiffies, rq->deadline)) {
if (!blk_mark_rq_complete(rq))
blk_mq_rq_timed_out(rq, reserved);
} else if (!data->next_set || time_after(data->next, rq->deadline)) {
data->next = rq->deadline;
data->next_set = 1;
}
}
static void blk_mq_timeout_work(struct work_struct *work)
{
struct request_queue *q =
container_of(work, struct request_queue, timeout_work);
struct blk_mq_timeout_data data = {
.next = 0,
.next_set = 0,
};
int i;
/* A deadlock might occur if a request is stuck requiring a
* timeout at the same time a queue freeze is waiting
* completion, since the timeout code would not be able to
* acquire the queue reference here.
*
* That's why we don't use blk_queue_enter here; instead, we use
* percpu_ref_tryget directly, because we need to be able to
* obtain a reference even in the short window between the queue
* starting to freeze, by dropping the first reference in
* blk_freeze_queue_start, and the moment the last request is
* consumed, marked by the instant q_usage_counter reaches
* zero.
*/
if (!percpu_ref_tryget(&q->q_usage_counter))
return;
blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &data);
if (data.next_set) {
data.next = blk_rq_timeout(round_jiffies_up(data.next));
mod_timer(&q->timeout, data.next);
} else {
struct blk_mq_hw_ctx *hctx;
queue_for_each_hw_ctx(q, hctx, i) {
/* the hctx may be unmapped, so check it here */
if (blk_mq_hw_queue_mapped(hctx))
blk_mq_tag_idle(hctx);
}
}
blk_queue_exit(q);
}
/*
* Reverse check our software queue for entries that we could potentially
* merge with. Currently includes a hand-wavy stop count of 8, to not spend
* too much time checking for merges.
*/
static bool blk_mq_attempt_merge(struct request_queue *q,
struct blk_mq_ctx *ctx, struct bio *bio)
{
struct request *rq;
int checked = 8;
list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) {
bool merged = false;
if (!checked--)
break;
if (!blk_rq_merge_ok(rq, bio))
continue;
switch (blk_try_merge(rq, bio)) {
case ELEVATOR_BACK_MERGE:
if (blk_mq_sched_allow_merge(q, rq, bio))
merged = bio_attempt_back_merge(q, rq, bio);
break;
case ELEVATOR_FRONT_MERGE:
if (blk_mq_sched_allow_merge(q, rq, bio))
merged = bio_attempt_front_merge(q, rq, bio);
break;
case ELEVATOR_DISCARD_MERGE:
merged = bio_attempt_discard_merge(q, rq, bio);
break;
default:
continue;
}
if (merged)
ctx->rq_merged++;
return merged;
}
return false;
}
struct flush_busy_ctx_data {
struct blk_mq_hw_ctx *hctx;
struct list_head *list;
};
static bool flush_busy_ctx(struct sbitmap *sb, unsigned int bitnr, void *data)
{
struct flush_busy_ctx_data *flush_data = data;
struct blk_mq_hw_ctx *hctx = flush_data->hctx;
struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
sbitmap_clear_bit(sb, bitnr);
spin_lock(&ctx->lock);
list_splice_tail_init(&ctx->rq_list, flush_data->list);
spin_unlock(&ctx->lock);
return true;
}
/*
* Process software queues that have been marked busy, splicing them
* to the for-dispatch
*/
void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list)
{
struct flush_busy_ctx_data data = {
.hctx = hctx,
.list = list,
};
sbitmap_for_each_set(&hctx->ctx_map, flush_busy_ctx, &data);
}
EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs);
static inline unsigned int queued_to_index(unsigned int queued)
{
if (!queued)
return 0;
return min(BLK_MQ_MAX_DISPATCH_ORDER - 1, ilog2(queued) + 1);
}
bool blk_mq_get_driver_tag(struct request *rq, struct blk_mq_hw_ctx **hctx,
bool wait)
{
struct blk_mq_alloc_data data = {
.q = rq->q,
.hctx = blk_mq_map_queue(rq->q, rq->mq_ctx->cpu),
.flags = wait ? 0 : BLK_MQ_REQ_NOWAIT,
};
might_sleep_if(wait);
if (rq->tag != -1)
goto done;
if (blk_mq_tag_is_reserved(data.hctx->sched_tags, rq->internal_tag))
data.flags |= BLK_MQ_REQ_RESERVED;
rq->tag = blk_mq_get_tag(&data);
if (rq->tag >= 0) {
if (blk_mq_tag_busy(data.hctx)) {
rq->rq_flags |= RQF_MQ_INFLIGHT;
atomic_inc(&data.hctx->nr_active);
}
data.hctx->tags->rqs[rq->tag] = rq;
}
done:
if (hctx)
*hctx = data.hctx;
return rq->tag != -1;
}
static void __blk_mq_put_driver_tag(struct blk_mq_hw_ctx *hctx,
struct request *rq)
{
blk_mq_put_tag(hctx, hctx->tags, rq->mq_ctx, rq->tag);
rq->tag = -1;
if (rq->rq_flags & RQF_MQ_INFLIGHT) {
rq->rq_flags &= ~RQF_MQ_INFLIGHT;
atomic_dec(&hctx->nr_active);
}
}
static void blk_mq_put_driver_tag_hctx(struct blk_mq_hw_ctx *hctx,
struct request *rq)
{
if (rq->tag == -1 || rq->internal_tag == -1)
return;
__blk_mq_put_driver_tag(hctx, rq);
}
static void blk_mq_put_driver_tag(struct request *rq)
{
struct blk_mq_hw_ctx *hctx;
if (rq->tag == -1 || rq->internal_tag == -1)
return;
hctx = blk_mq_map_queue(rq->q, rq->mq_ctx->cpu);
__blk_mq_put_driver_tag(hctx, rq);
}
/*
* If we fail getting a driver tag because all the driver tags are already
* assigned and on the dispatch list, BUT the first entry does not have a
* tag, then we could deadlock. For that case, move entries with assigned
* driver tags to the front, leaving the set of tagged requests in the
* same order, and the untagged set in the same order.
*/
static bool reorder_tags_to_front(struct list_head *list)
{
struct request *rq, *tmp, *first = NULL;
list_for_each_entry_safe_reverse(rq, tmp, list, queuelist) {
if (rq == first)
break;
if (rq->tag != -1) {
list_move(&rq->queuelist, list);
if (!first)
first = rq;
}
}
return first != NULL;
}
static int blk_mq_dispatch_wake(wait_queue_t *wait, unsigned mode, int flags,
void *key)
{
struct blk_mq_hw_ctx *hctx;
hctx = container_of(wait, struct blk_mq_hw_ctx, dispatch_wait);
list_del(&wait->task_list);
clear_bit_unlock(BLK_MQ_S_TAG_WAITING, &hctx->state);
blk_mq_run_hw_queue(hctx, true);
return 1;
}
static bool blk_mq_dispatch_wait_add(struct blk_mq_hw_ctx *hctx)
{
struct sbq_wait_state *ws;
/*
* The TAG_WAITING bit serves as a lock protecting hctx->dispatch_wait.
* The thread which wins the race to grab this bit adds the hardware
* queue to the wait queue.
*/
if (test_bit(BLK_MQ_S_TAG_WAITING, &hctx->state) ||
test_and_set_bit_lock(BLK_MQ_S_TAG_WAITING, &hctx->state))
return false;
init_waitqueue_func_entry(&hctx->dispatch_wait, blk_mq_dispatch_wake);
ws = bt_wait_ptr(&hctx->tags->bitmap_tags, hctx);
/*
* As soon as this returns, it's no longer safe to fiddle with
* hctx->dispatch_wait, since a completion can wake up the wait queue
* and unlock the bit.
*/
add_wait_queue(&ws->wait, &hctx->dispatch_wait);
return true;
}
bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list)
{
struct blk_mq_hw_ctx *hctx;
struct request *rq;
int errors, queued, ret = BLK_MQ_RQ_QUEUE_OK;
if (list_empty(list))
return false;
/*
* Now process all the entries, sending them to the driver.
*/
errors = queued = 0;
do {
struct blk_mq_queue_data bd;
rq = list_first_entry(list, struct request, queuelist);