Merge tag 'dax-fixes-6.1-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm...
[platform/kernel/linux-starfive.git] / block / blk-mq.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Block multiqueue core code
4  *
5  * Copyright (C) 2013-2014 Jens Axboe
6  * Copyright (C) 2013-2014 Christoph Hellwig
7  */
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/blk-integrity.h>
14 #include <linux/kmemleak.h>
15 #include <linux/mm.h>
16 #include <linux/init.h>
17 #include <linux/slab.h>
18 #include <linux/workqueue.h>
19 #include <linux/smp.h>
20 #include <linux/interrupt.h>
21 #include <linux/llist.h>
22 #include <linux/cpu.h>
23 #include <linux/cache.h>
24 #include <linux/sched/sysctl.h>
25 #include <linux/sched/topology.h>
26 #include <linux/sched/signal.h>
27 #include <linux/delay.h>
28 #include <linux/crash_dump.h>
29 #include <linux/prefetch.h>
30 #include <linux/blk-crypto.h>
31 #include <linux/part_stat.h>
32
33 #include <trace/events/block.h>
34
35 #include <linux/blk-mq.h>
36 #include <linux/t10-pi.h>
37 #include "blk.h"
38 #include "blk-mq.h"
39 #include "blk-mq-debugfs.h"
40 #include "blk-mq-tag.h"
41 #include "blk-pm.h"
42 #include "blk-stat.h"
43 #include "blk-mq-sched.h"
44 #include "blk-rq-qos.h"
45 #include "blk-ioprio.h"
46
47 static DEFINE_PER_CPU(struct llist_head, blk_cpu_done);
48
49 static void blk_mq_poll_stats_start(struct request_queue *q);
50 static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb);
51
52 static int blk_mq_poll_stats_bkt(const struct request *rq)
53 {
54         int ddir, sectors, bucket;
55
56         ddir = rq_data_dir(rq);
57         sectors = blk_rq_stats_sectors(rq);
58
59         bucket = ddir + 2 * ilog2(sectors);
60
61         if (bucket < 0)
62                 return -1;
63         else if (bucket >= BLK_MQ_POLL_STATS_BKTS)
64                 return ddir + BLK_MQ_POLL_STATS_BKTS - 2;
65
66         return bucket;
67 }
68
69 #define BLK_QC_T_SHIFT          16
70 #define BLK_QC_T_INTERNAL       (1U << 31)
71
72 static inline struct blk_mq_hw_ctx *blk_qc_to_hctx(struct request_queue *q,
73                 blk_qc_t qc)
74 {
75         return xa_load(&q->hctx_table,
76                         (qc & ~BLK_QC_T_INTERNAL) >> BLK_QC_T_SHIFT);
77 }
78
79 static inline struct request *blk_qc_to_rq(struct blk_mq_hw_ctx *hctx,
80                 blk_qc_t qc)
81 {
82         unsigned int tag = qc & ((1U << BLK_QC_T_SHIFT) - 1);
83
84         if (qc & BLK_QC_T_INTERNAL)
85                 return blk_mq_tag_to_rq(hctx->sched_tags, tag);
86         return blk_mq_tag_to_rq(hctx->tags, tag);
87 }
88
89 static inline blk_qc_t blk_rq_to_qc(struct request *rq)
90 {
91         return (rq->mq_hctx->queue_num << BLK_QC_T_SHIFT) |
92                 (rq->tag != -1 ?
93                  rq->tag : (rq->internal_tag | BLK_QC_T_INTERNAL));
94 }
95
96 /*
97  * Check if any of the ctx, dispatch list or elevator
98  * have pending work in this hardware queue.
99  */
100 static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx)
101 {
102         return !list_empty_careful(&hctx->dispatch) ||
103                 sbitmap_any_bit_set(&hctx->ctx_map) ||
104                         blk_mq_sched_has_work(hctx);
105 }
106
107 /*
108  * Mark this ctx as having pending work in this hardware queue
109  */
110 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx *hctx,
111                                      struct blk_mq_ctx *ctx)
112 {
113         const int bit = ctx->index_hw[hctx->type];
114
115         if (!sbitmap_test_bit(&hctx->ctx_map, bit))
116                 sbitmap_set_bit(&hctx->ctx_map, bit);
117 }
118
119 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,
120                                       struct blk_mq_ctx *ctx)
121 {
122         const int bit = ctx->index_hw[hctx->type];
123
124         sbitmap_clear_bit(&hctx->ctx_map, bit);
125 }
126
127 struct mq_inflight {
128         struct block_device *part;
129         unsigned int inflight[2];
130 };
131
132 static bool blk_mq_check_inflight(struct request *rq, void *priv)
133 {
134         struct mq_inflight *mi = priv;
135
136         if (rq->part && blk_do_io_stat(rq) &&
137             (!mi->part->bd_partno || rq->part == mi->part) &&
138             blk_mq_rq_state(rq) == MQ_RQ_IN_FLIGHT)
139                 mi->inflight[rq_data_dir(rq)]++;
140
141         return true;
142 }
143
144 unsigned int blk_mq_in_flight(struct request_queue *q,
145                 struct block_device *part)
146 {
147         struct mq_inflight mi = { .part = part };
148
149         blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight, &mi);
150
151         return mi.inflight[0] + mi.inflight[1];
152 }
153
154 void blk_mq_in_flight_rw(struct request_queue *q, struct block_device *part,
155                 unsigned int inflight[2])
156 {
157         struct mq_inflight mi = { .part = part };
158
159         blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight, &mi);
160         inflight[0] = mi.inflight[0];
161         inflight[1] = mi.inflight[1];
162 }
163
164 void blk_freeze_queue_start(struct request_queue *q)
165 {
166         mutex_lock(&q->mq_freeze_lock);
167         if (++q->mq_freeze_depth == 1) {
168                 percpu_ref_kill(&q->q_usage_counter);
169                 mutex_unlock(&q->mq_freeze_lock);
170                 if (queue_is_mq(q))
171                         blk_mq_run_hw_queues(q, false);
172         } else {
173                 mutex_unlock(&q->mq_freeze_lock);
174         }
175 }
176 EXPORT_SYMBOL_GPL(blk_freeze_queue_start);
177
178 void blk_mq_freeze_queue_wait(struct request_queue *q)
179 {
180         wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->q_usage_counter));
181 }
182 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait);
183
184 int blk_mq_freeze_queue_wait_timeout(struct request_queue *q,
185                                      unsigned long timeout)
186 {
187         return wait_event_timeout(q->mq_freeze_wq,
188                                         percpu_ref_is_zero(&q->q_usage_counter),
189                                         timeout);
190 }
191 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout);
192
193 /*
194  * Guarantee no request is in use, so we can change any data structure of
195  * the queue afterward.
196  */
197 void blk_freeze_queue(struct request_queue *q)
198 {
199         /*
200          * In the !blk_mq case we are only calling this to kill the
201          * q_usage_counter, otherwise this increases the freeze depth
202          * and waits for it to return to zero.  For this reason there is
203          * no blk_unfreeze_queue(), and blk_freeze_queue() is not
204          * exported to drivers as the only user for unfreeze is blk_mq.
205          */
206         blk_freeze_queue_start(q);
207         blk_mq_freeze_queue_wait(q);
208 }
209
210 void blk_mq_freeze_queue(struct request_queue *q)
211 {
212         /*
213          * ...just an alias to keep freeze and unfreeze actions balanced
214          * in the blk_mq_* namespace
215          */
216         blk_freeze_queue(q);
217 }
218 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue);
219
220 void __blk_mq_unfreeze_queue(struct request_queue *q, bool force_atomic)
221 {
222         mutex_lock(&q->mq_freeze_lock);
223         if (force_atomic)
224                 q->q_usage_counter.data->force_atomic = true;
225         q->mq_freeze_depth--;
226         WARN_ON_ONCE(q->mq_freeze_depth < 0);
227         if (!q->mq_freeze_depth) {
228                 percpu_ref_resurrect(&q->q_usage_counter);
229                 wake_up_all(&q->mq_freeze_wq);
230         }
231         mutex_unlock(&q->mq_freeze_lock);
232 }
233
234 void blk_mq_unfreeze_queue(struct request_queue *q)
235 {
236         __blk_mq_unfreeze_queue(q, false);
237 }
238 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue);
239
240 /*
241  * FIXME: replace the scsi_internal_device_*block_nowait() calls in the
242  * mpt3sas driver such that this function can be removed.
243  */
244 void blk_mq_quiesce_queue_nowait(struct request_queue *q)
245 {
246         unsigned long flags;
247
248         spin_lock_irqsave(&q->queue_lock, flags);
249         if (!q->quiesce_depth++)
250                 blk_queue_flag_set(QUEUE_FLAG_QUIESCED, q);
251         spin_unlock_irqrestore(&q->queue_lock, flags);
252 }
253 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait);
254
255 /**
256  * blk_mq_wait_quiesce_done() - wait until in-progress quiesce is done
257  * @q: request queue.
258  *
259  * Note: it is driver's responsibility for making sure that quiesce has
260  * been started.
261  */
262 void blk_mq_wait_quiesce_done(struct request_queue *q)
263 {
264         if (blk_queue_has_srcu(q))
265                 synchronize_srcu(q->srcu);
266         else
267                 synchronize_rcu();
268 }
269 EXPORT_SYMBOL_GPL(blk_mq_wait_quiesce_done);
270
271 /**
272  * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished
273  * @q: request queue.
274  *
275  * Note: this function does not prevent that the struct request end_io()
276  * callback function is invoked. Once this function is returned, we make
277  * sure no dispatch can happen until the queue is unquiesced via
278  * blk_mq_unquiesce_queue().
279  */
280 void blk_mq_quiesce_queue(struct request_queue *q)
281 {
282         blk_mq_quiesce_queue_nowait(q);
283         blk_mq_wait_quiesce_done(q);
284 }
285 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue);
286
287 /*
288  * blk_mq_unquiesce_queue() - counterpart of blk_mq_quiesce_queue()
289  * @q: request queue.
290  *
291  * This function recovers queue into the state before quiescing
292  * which is done by blk_mq_quiesce_queue.
293  */
294 void blk_mq_unquiesce_queue(struct request_queue *q)
295 {
296         unsigned long flags;
297         bool run_queue = false;
298
299         spin_lock_irqsave(&q->queue_lock, flags);
300         if (WARN_ON_ONCE(q->quiesce_depth <= 0)) {
301                 ;
302         } else if (!--q->quiesce_depth) {
303                 blk_queue_flag_clear(QUEUE_FLAG_QUIESCED, q);
304                 run_queue = true;
305         }
306         spin_unlock_irqrestore(&q->queue_lock, flags);
307
308         /* dispatch requests which are inserted during quiescing */
309         if (run_queue)
310                 blk_mq_run_hw_queues(q, true);
311 }
312 EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue);
313
314 void blk_mq_wake_waiters(struct request_queue *q)
315 {
316         struct blk_mq_hw_ctx *hctx;
317         unsigned long i;
318
319         queue_for_each_hw_ctx(q, hctx, i)
320                 if (blk_mq_hw_queue_mapped(hctx))
321                         blk_mq_tag_wakeup_all(hctx->tags, true);
322 }
323
324 void blk_rq_init(struct request_queue *q, struct request *rq)
325 {
326         memset(rq, 0, sizeof(*rq));
327
328         INIT_LIST_HEAD(&rq->queuelist);
329         rq->q = q;
330         rq->__sector = (sector_t) -1;
331         INIT_HLIST_NODE(&rq->hash);
332         RB_CLEAR_NODE(&rq->rb_node);
333         rq->tag = BLK_MQ_NO_TAG;
334         rq->internal_tag = BLK_MQ_NO_TAG;
335         rq->start_time_ns = ktime_get_ns();
336         rq->part = NULL;
337         blk_crypto_rq_set_defaults(rq);
338 }
339 EXPORT_SYMBOL(blk_rq_init);
340
341 static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
342                 struct blk_mq_tags *tags, unsigned int tag, u64 alloc_time_ns)
343 {
344         struct blk_mq_ctx *ctx = data->ctx;
345         struct blk_mq_hw_ctx *hctx = data->hctx;
346         struct request_queue *q = data->q;
347         struct request *rq = tags->static_rqs[tag];
348
349         rq->q = q;
350         rq->mq_ctx = ctx;
351         rq->mq_hctx = hctx;
352         rq->cmd_flags = data->cmd_flags;
353
354         if (data->flags & BLK_MQ_REQ_PM)
355                 data->rq_flags |= RQF_PM;
356         if (blk_queue_io_stat(q))
357                 data->rq_flags |= RQF_IO_STAT;
358         rq->rq_flags = data->rq_flags;
359
360         if (!(data->rq_flags & RQF_ELV)) {
361                 rq->tag = tag;
362                 rq->internal_tag = BLK_MQ_NO_TAG;
363         } else {
364                 rq->tag = BLK_MQ_NO_TAG;
365                 rq->internal_tag = tag;
366         }
367         rq->timeout = 0;
368
369         if (blk_mq_need_time_stamp(rq))
370                 rq->start_time_ns = ktime_get_ns();
371         else
372                 rq->start_time_ns = 0;
373         rq->part = NULL;
374 #ifdef CONFIG_BLK_RQ_ALLOC_TIME
375         rq->alloc_time_ns = alloc_time_ns;
376 #endif
377         rq->io_start_time_ns = 0;
378         rq->stats_sectors = 0;
379         rq->nr_phys_segments = 0;
380 #if defined(CONFIG_BLK_DEV_INTEGRITY)
381         rq->nr_integrity_segments = 0;
382 #endif
383         rq->end_io = NULL;
384         rq->end_io_data = NULL;
385
386         blk_crypto_rq_set_defaults(rq);
387         INIT_LIST_HEAD(&rq->queuelist);
388         /* tag was already set */
389         WRITE_ONCE(rq->deadline, 0);
390         req_ref_set(rq, 1);
391
392         if (rq->rq_flags & RQF_ELV) {
393                 struct elevator_queue *e = data->q->elevator;
394
395                 INIT_HLIST_NODE(&rq->hash);
396                 RB_CLEAR_NODE(&rq->rb_node);
397
398                 if (!op_is_flush(data->cmd_flags) &&
399                     e->type->ops.prepare_request) {
400                         e->type->ops.prepare_request(rq);
401                         rq->rq_flags |= RQF_ELVPRIV;
402                 }
403         }
404
405         return rq;
406 }
407
408 static inline struct request *
409 __blk_mq_alloc_requests_batch(struct blk_mq_alloc_data *data,
410                 u64 alloc_time_ns)
411 {
412         unsigned int tag, tag_offset;
413         struct blk_mq_tags *tags;
414         struct request *rq;
415         unsigned long tag_mask;
416         int i, nr = 0;
417
418         tag_mask = blk_mq_get_tags(data, data->nr_tags, &tag_offset);
419         if (unlikely(!tag_mask))
420                 return NULL;
421
422         tags = blk_mq_tags_from_data(data);
423         for (i = 0; tag_mask; i++) {
424                 if (!(tag_mask & (1UL << i)))
425                         continue;
426                 tag = tag_offset + i;
427                 prefetch(tags->static_rqs[tag]);
428                 tag_mask &= ~(1UL << i);
429                 rq = blk_mq_rq_ctx_init(data, tags, tag, alloc_time_ns);
430                 rq_list_add(data->cached_rq, rq);
431                 nr++;
432         }
433         /* caller already holds a reference, add for remainder */
434         percpu_ref_get_many(&data->q->q_usage_counter, nr - 1);
435         data->nr_tags -= nr;
436
437         return rq_list_pop(data->cached_rq);
438 }
439
440 static struct request *__blk_mq_alloc_requests(struct blk_mq_alloc_data *data)
441 {
442         struct request_queue *q = data->q;
443         u64 alloc_time_ns = 0;
444         struct request *rq;
445         unsigned int tag;
446
447         /* alloc_time includes depth and tag waits */
448         if (blk_queue_rq_alloc_time(q))
449                 alloc_time_ns = ktime_get_ns();
450
451         if (data->cmd_flags & REQ_NOWAIT)
452                 data->flags |= BLK_MQ_REQ_NOWAIT;
453
454         if (q->elevator) {
455                 struct elevator_queue *e = q->elevator;
456
457                 data->rq_flags |= RQF_ELV;
458
459                 /*
460                  * Flush/passthrough requests are special and go directly to the
461                  * dispatch list. Don't include reserved tags in the
462                  * limiting, as it isn't useful.
463                  */
464                 if (!op_is_flush(data->cmd_flags) &&
465                     !blk_op_is_passthrough(data->cmd_flags) &&
466                     e->type->ops.limit_depth &&
467                     !(data->flags & BLK_MQ_REQ_RESERVED))
468                         e->type->ops.limit_depth(data->cmd_flags, data);
469         }
470
471 retry:
472         data->ctx = blk_mq_get_ctx(q);
473         data->hctx = blk_mq_map_queue(q, data->cmd_flags, data->ctx);
474         if (!(data->rq_flags & RQF_ELV))
475                 blk_mq_tag_busy(data->hctx);
476
477         if (data->flags & BLK_MQ_REQ_RESERVED)
478                 data->rq_flags |= RQF_RESV;
479
480         /*
481          * Try batched alloc if we want more than 1 tag.
482          */
483         if (data->nr_tags > 1) {
484                 rq = __blk_mq_alloc_requests_batch(data, alloc_time_ns);
485                 if (rq)
486                         return rq;
487                 data->nr_tags = 1;
488         }
489
490         /*
491          * Waiting allocations only fail because of an inactive hctx.  In that
492          * case just retry the hctx assignment and tag allocation as CPU hotplug
493          * should have migrated us to an online CPU by now.
494          */
495         tag = blk_mq_get_tag(data);
496         if (tag == BLK_MQ_NO_TAG) {
497                 if (data->flags & BLK_MQ_REQ_NOWAIT)
498                         return NULL;
499                 /*
500                  * Give up the CPU and sleep for a random short time to
501                  * ensure that thread using a realtime scheduling class
502                  * are migrated off the CPU, and thus off the hctx that
503                  * is going away.
504                  */
505                 msleep(3);
506                 goto retry;
507         }
508
509         return blk_mq_rq_ctx_init(data, blk_mq_tags_from_data(data), tag,
510                                         alloc_time_ns);
511 }
512
513 static struct request *blk_mq_rq_cache_fill(struct request_queue *q,
514                                             struct blk_plug *plug,
515                                             blk_opf_t opf,
516                                             blk_mq_req_flags_t flags)
517 {
518         struct blk_mq_alloc_data data = {
519                 .q              = q,
520                 .flags          = flags,
521                 .cmd_flags      = opf,
522                 .nr_tags        = plug->nr_ios,
523                 .cached_rq      = &plug->cached_rq,
524         };
525         struct request *rq;
526
527         if (blk_queue_enter(q, flags))
528                 return NULL;
529
530         plug->nr_ios = 1;
531
532         rq = __blk_mq_alloc_requests(&data);
533         if (unlikely(!rq))
534                 blk_queue_exit(q);
535         return rq;
536 }
537
538 static struct request *blk_mq_alloc_cached_request(struct request_queue *q,
539                                                    blk_opf_t opf,
540                                                    blk_mq_req_flags_t flags)
541 {
542         struct blk_plug *plug = current->plug;
543         struct request *rq;
544
545         if (!plug)
546                 return NULL;
547         if (rq_list_empty(plug->cached_rq)) {
548                 if (plug->nr_ios == 1)
549                         return NULL;
550                 rq = blk_mq_rq_cache_fill(q, plug, opf, flags);
551                 if (rq)
552                         goto got_it;
553                 return NULL;
554         }
555         rq = rq_list_peek(&plug->cached_rq);
556         if (!rq || rq->q != q)
557                 return NULL;
558
559         if (blk_mq_get_hctx_type(opf) != rq->mq_hctx->type)
560                 return NULL;
561         if (op_is_flush(rq->cmd_flags) != op_is_flush(opf))
562                 return NULL;
563
564         plug->cached_rq = rq_list_next(rq);
565 got_it:
566         rq->cmd_flags = opf;
567         INIT_LIST_HEAD(&rq->queuelist);
568         return rq;
569 }
570
571 struct request *blk_mq_alloc_request(struct request_queue *q, blk_opf_t opf,
572                 blk_mq_req_flags_t flags)
573 {
574         struct request *rq;
575
576         rq = blk_mq_alloc_cached_request(q, opf, flags);
577         if (!rq) {
578                 struct blk_mq_alloc_data data = {
579                         .q              = q,
580                         .flags          = flags,
581                         .cmd_flags      = opf,
582                         .nr_tags        = 1,
583                 };
584                 int ret;
585
586                 ret = blk_queue_enter(q, flags);
587                 if (ret)
588                         return ERR_PTR(ret);
589
590                 rq = __blk_mq_alloc_requests(&data);
591                 if (!rq)
592                         goto out_queue_exit;
593         }
594         rq->__data_len = 0;
595         rq->__sector = (sector_t) -1;
596         rq->bio = rq->biotail = NULL;
597         return rq;
598 out_queue_exit:
599         blk_queue_exit(q);
600         return ERR_PTR(-EWOULDBLOCK);
601 }
602 EXPORT_SYMBOL(blk_mq_alloc_request);
603
604 struct request *blk_mq_alloc_request_hctx(struct request_queue *q,
605         blk_opf_t opf, blk_mq_req_flags_t flags, unsigned int hctx_idx)
606 {
607         struct blk_mq_alloc_data data = {
608                 .q              = q,
609                 .flags          = flags,
610                 .cmd_flags      = opf,
611                 .nr_tags        = 1,
612         };
613         u64 alloc_time_ns = 0;
614         struct request *rq;
615         unsigned int cpu;
616         unsigned int tag;
617         int ret;
618
619         /* alloc_time includes depth and tag waits */
620         if (blk_queue_rq_alloc_time(q))
621                 alloc_time_ns = ktime_get_ns();
622
623         /*
624          * If the tag allocator sleeps we could get an allocation for a
625          * different hardware context.  No need to complicate the low level
626          * allocator for this for the rare use case of a command tied to
627          * a specific queue.
628          */
629         if (WARN_ON_ONCE(!(flags & (BLK_MQ_REQ_NOWAIT | BLK_MQ_REQ_RESERVED))))
630                 return ERR_PTR(-EINVAL);
631
632         if (hctx_idx >= q->nr_hw_queues)
633                 return ERR_PTR(-EIO);
634
635         ret = blk_queue_enter(q, flags);
636         if (ret)
637                 return ERR_PTR(ret);
638
639         /*
640          * Check if the hardware context is actually mapped to anything.
641          * If not tell the caller that it should skip this queue.
642          */
643         ret = -EXDEV;
644         data.hctx = xa_load(&q->hctx_table, hctx_idx);
645         if (!blk_mq_hw_queue_mapped(data.hctx))
646                 goto out_queue_exit;
647         cpu = cpumask_first_and(data.hctx->cpumask, cpu_online_mask);
648         if (cpu >= nr_cpu_ids)
649                 goto out_queue_exit;
650         data.ctx = __blk_mq_get_ctx(q, cpu);
651
652         if (!q->elevator)
653                 blk_mq_tag_busy(data.hctx);
654         else
655                 data.rq_flags |= RQF_ELV;
656
657         if (flags & BLK_MQ_REQ_RESERVED)
658                 data.rq_flags |= RQF_RESV;
659
660         ret = -EWOULDBLOCK;
661         tag = blk_mq_get_tag(&data);
662         if (tag == BLK_MQ_NO_TAG)
663                 goto out_queue_exit;
664         rq = blk_mq_rq_ctx_init(&data, blk_mq_tags_from_data(&data), tag,
665                                         alloc_time_ns);
666         rq->__data_len = 0;
667         rq->__sector = (sector_t) -1;
668         rq->bio = rq->biotail = NULL;
669         return rq;
670
671 out_queue_exit:
672         blk_queue_exit(q);
673         return ERR_PTR(ret);
674 }
675 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx);
676
677 static void __blk_mq_free_request(struct request *rq)
678 {
679         struct request_queue *q = rq->q;
680         struct blk_mq_ctx *ctx = rq->mq_ctx;
681         struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
682         const int sched_tag = rq->internal_tag;
683
684         blk_crypto_free_request(rq);
685         blk_pm_mark_last_busy(rq);
686         rq->mq_hctx = NULL;
687         if (rq->tag != BLK_MQ_NO_TAG)
688                 blk_mq_put_tag(hctx->tags, ctx, rq->tag);
689         if (sched_tag != BLK_MQ_NO_TAG)
690                 blk_mq_put_tag(hctx->sched_tags, ctx, sched_tag);
691         blk_mq_sched_restart(hctx);
692         blk_queue_exit(q);
693 }
694
695 void blk_mq_free_request(struct request *rq)
696 {
697         struct request_queue *q = rq->q;
698         struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
699
700         if ((rq->rq_flags & RQF_ELVPRIV) &&
701             q->elevator->type->ops.finish_request)
702                 q->elevator->type->ops.finish_request(rq);
703
704         if (rq->rq_flags & RQF_MQ_INFLIGHT)
705                 __blk_mq_dec_active_requests(hctx);
706
707         if (unlikely(laptop_mode && !blk_rq_is_passthrough(rq)))
708                 laptop_io_completion(q->disk->bdi);
709
710         rq_qos_done(q, rq);
711
712         WRITE_ONCE(rq->state, MQ_RQ_IDLE);
713         if (req_ref_put_and_test(rq))
714                 __blk_mq_free_request(rq);
715 }
716 EXPORT_SYMBOL_GPL(blk_mq_free_request);
717
718 void blk_mq_free_plug_rqs(struct blk_plug *plug)
719 {
720         struct request *rq;
721
722         while ((rq = rq_list_pop(&plug->cached_rq)) != NULL)
723                 blk_mq_free_request(rq);
724 }
725
726 void blk_dump_rq_flags(struct request *rq, char *msg)
727 {
728         printk(KERN_INFO "%s: dev %s: flags=%llx\n", msg,
729                 rq->q->disk ? rq->q->disk->disk_name : "?",
730                 (__force unsigned long long) rq->cmd_flags);
731
732         printk(KERN_INFO "  sector %llu, nr/cnr %u/%u\n",
733                (unsigned long long)blk_rq_pos(rq),
734                blk_rq_sectors(rq), blk_rq_cur_sectors(rq));
735         printk(KERN_INFO "  bio %p, biotail %p, len %u\n",
736                rq->bio, rq->biotail, blk_rq_bytes(rq));
737 }
738 EXPORT_SYMBOL(blk_dump_rq_flags);
739
740 static void req_bio_endio(struct request *rq, struct bio *bio,
741                           unsigned int nbytes, blk_status_t error)
742 {
743         if (unlikely(error)) {
744                 bio->bi_status = error;
745         } else if (req_op(rq) == REQ_OP_ZONE_APPEND) {
746                 /*
747                  * Partial zone append completions cannot be supported as the
748                  * BIO fragments may end up not being written sequentially.
749                  */
750                 if (bio->bi_iter.bi_size != nbytes)
751                         bio->bi_status = BLK_STS_IOERR;
752                 else
753                         bio->bi_iter.bi_sector = rq->__sector;
754         }
755
756         bio_advance(bio, nbytes);
757
758         if (unlikely(rq->rq_flags & RQF_QUIET))
759                 bio_set_flag(bio, BIO_QUIET);
760         /* don't actually finish bio if it's part of flush sequence */
761         if (bio->bi_iter.bi_size == 0 && !(rq->rq_flags & RQF_FLUSH_SEQ))
762                 bio_endio(bio);
763 }
764
765 static void blk_account_io_completion(struct request *req, unsigned int bytes)
766 {
767         if (req->part && blk_do_io_stat(req)) {
768                 const int sgrp = op_stat_group(req_op(req));
769
770                 part_stat_lock();
771                 part_stat_add(req->part, sectors[sgrp], bytes >> 9);
772                 part_stat_unlock();
773         }
774 }
775
776 static void blk_print_req_error(struct request *req, blk_status_t status)
777 {
778         printk_ratelimited(KERN_ERR
779                 "%s error, dev %s, sector %llu op 0x%x:(%s) flags 0x%x "
780                 "phys_seg %u prio class %u\n",
781                 blk_status_to_str(status),
782                 req->q->disk ? req->q->disk->disk_name : "?",
783                 blk_rq_pos(req), (__force u32)req_op(req),
784                 blk_op_str(req_op(req)),
785                 (__force u32)(req->cmd_flags & ~REQ_OP_MASK),
786                 req->nr_phys_segments,
787                 IOPRIO_PRIO_CLASS(req->ioprio));
788 }
789
790 /*
791  * Fully end IO on a request. Does not support partial completions, or
792  * errors.
793  */
794 static void blk_complete_request(struct request *req)
795 {
796         const bool is_flush = (req->rq_flags & RQF_FLUSH_SEQ) != 0;
797         int total_bytes = blk_rq_bytes(req);
798         struct bio *bio = req->bio;
799
800         trace_block_rq_complete(req, BLK_STS_OK, total_bytes);
801
802         if (!bio)
803                 return;
804
805 #ifdef CONFIG_BLK_DEV_INTEGRITY
806         if (blk_integrity_rq(req) && req_op(req) == REQ_OP_READ)
807                 req->q->integrity.profile->complete_fn(req, total_bytes);
808 #endif
809
810         blk_account_io_completion(req, total_bytes);
811
812         do {
813                 struct bio *next = bio->bi_next;
814
815                 /* Completion has already been traced */
816                 bio_clear_flag(bio, BIO_TRACE_COMPLETION);
817
818                 if (req_op(req) == REQ_OP_ZONE_APPEND)
819                         bio->bi_iter.bi_sector = req->__sector;
820
821                 if (!is_flush)
822                         bio_endio(bio);
823                 bio = next;
824         } while (bio);
825
826         /*
827          * Reset counters so that the request stacking driver
828          * can find how many bytes remain in the request
829          * later.
830          */
831         if (!req->end_io) {
832                 req->bio = NULL;
833                 req->__data_len = 0;
834         }
835 }
836
837 /**
838  * blk_update_request - Complete multiple bytes without completing the request
839  * @req:      the request being processed
840  * @error:    block status code
841  * @nr_bytes: number of bytes to complete for @req
842  *
843  * Description:
844  *     Ends I/O on a number of bytes attached to @req, but doesn't complete
845  *     the request structure even if @req doesn't have leftover.
846  *     If @req has leftover, sets it up for the next range of segments.
847  *
848  *     Passing the result of blk_rq_bytes() as @nr_bytes guarantees
849  *     %false return from this function.
850  *
851  * Note:
852  *      The RQF_SPECIAL_PAYLOAD flag is ignored on purpose in this function
853  *      except in the consistency check at the end of this function.
854  *
855  * Return:
856  *     %false - this request doesn't have any more data
857  *     %true  - this request has more data
858  **/
859 bool blk_update_request(struct request *req, blk_status_t error,
860                 unsigned int nr_bytes)
861 {
862         int total_bytes;
863
864         trace_block_rq_complete(req, error, nr_bytes);
865
866         if (!req->bio)
867                 return false;
868
869 #ifdef CONFIG_BLK_DEV_INTEGRITY
870         if (blk_integrity_rq(req) && req_op(req) == REQ_OP_READ &&
871             error == BLK_STS_OK)
872                 req->q->integrity.profile->complete_fn(req, nr_bytes);
873 #endif
874
875         if (unlikely(error && !blk_rq_is_passthrough(req) &&
876                      !(req->rq_flags & RQF_QUIET)) &&
877                      !test_bit(GD_DEAD, &req->q->disk->state)) {
878                 blk_print_req_error(req, error);
879                 trace_block_rq_error(req, error, nr_bytes);
880         }
881
882         blk_account_io_completion(req, nr_bytes);
883
884         total_bytes = 0;
885         while (req->bio) {
886                 struct bio *bio = req->bio;
887                 unsigned bio_bytes = min(bio->bi_iter.bi_size, nr_bytes);
888
889                 if (bio_bytes == bio->bi_iter.bi_size)
890                         req->bio = bio->bi_next;
891
892                 /* Completion has already been traced */
893                 bio_clear_flag(bio, BIO_TRACE_COMPLETION);
894                 req_bio_endio(req, bio, bio_bytes, error);
895
896                 total_bytes += bio_bytes;
897                 nr_bytes -= bio_bytes;
898
899                 if (!nr_bytes)
900                         break;
901         }
902
903         /*
904          * completely done
905          */
906         if (!req->bio) {
907                 /*
908                  * Reset counters so that the request stacking driver
909                  * can find how many bytes remain in the request
910                  * later.
911                  */
912                 req->__data_len = 0;
913                 return false;
914         }
915
916         req->__data_len -= total_bytes;
917
918         /* update sector only for requests with clear definition of sector */
919         if (!blk_rq_is_passthrough(req))
920                 req->__sector += total_bytes >> 9;
921
922         /* mixed attributes always follow the first bio */
923         if (req->rq_flags & RQF_MIXED_MERGE) {
924                 req->cmd_flags &= ~REQ_FAILFAST_MASK;
925                 req->cmd_flags |= req->bio->bi_opf & REQ_FAILFAST_MASK;
926         }
927
928         if (!(req->rq_flags & RQF_SPECIAL_PAYLOAD)) {
929                 /*
930                  * If total number of sectors is less than the first segment
931                  * size, something has gone terribly wrong.
932                  */
933                 if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) {
934                         blk_dump_rq_flags(req, "request botched");
935                         req->__data_len = blk_rq_cur_bytes(req);
936                 }
937
938                 /* recalculate the number of segments */
939                 req->nr_phys_segments = blk_recalc_rq_segments(req);
940         }
941
942         return true;
943 }
944 EXPORT_SYMBOL_GPL(blk_update_request);
945
946 static void __blk_account_io_done(struct request *req, u64 now)
947 {
948         const int sgrp = op_stat_group(req_op(req));
949
950         part_stat_lock();
951         update_io_ticks(req->part, jiffies, true);
952         part_stat_inc(req->part, ios[sgrp]);
953         part_stat_add(req->part, nsecs[sgrp], now - req->start_time_ns);
954         part_stat_unlock();
955 }
956
957 static inline void blk_account_io_done(struct request *req, u64 now)
958 {
959         /*
960          * Account IO completion.  flush_rq isn't accounted as a
961          * normal IO on queueing nor completion.  Accounting the
962          * containing request is enough.
963          */
964         if (blk_do_io_stat(req) && req->part &&
965             !(req->rq_flags & RQF_FLUSH_SEQ))
966                 __blk_account_io_done(req, now);
967 }
968
969 static void __blk_account_io_start(struct request *rq)
970 {
971         /*
972          * All non-passthrough requests are created from a bio with one
973          * exception: when a flush command that is part of a flush sequence
974          * generated by the state machine in blk-flush.c is cloned onto the
975          * lower device by dm-multipath we can get here without a bio.
976          */
977         if (rq->bio)
978                 rq->part = rq->bio->bi_bdev;
979         else
980                 rq->part = rq->q->disk->part0;
981
982         part_stat_lock();
983         update_io_ticks(rq->part, jiffies, false);
984         part_stat_unlock();
985 }
986
987 static inline void blk_account_io_start(struct request *req)
988 {
989         if (blk_do_io_stat(req))
990                 __blk_account_io_start(req);
991 }
992
993 static inline void __blk_mq_end_request_acct(struct request *rq, u64 now)
994 {
995         if (rq->rq_flags & RQF_STATS) {
996                 blk_mq_poll_stats_start(rq->q);
997                 blk_stat_add(rq, now);
998         }
999
1000         blk_mq_sched_completed_request(rq, now);
1001         blk_account_io_done(rq, now);
1002 }
1003
1004 inline void __blk_mq_end_request(struct request *rq, blk_status_t error)
1005 {
1006         if (blk_mq_need_time_stamp(rq))
1007                 __blk_mq_end_request_acct(rq, ktime_get_ns());
1008
1009         if (rq->end_io) {
1010                 rq_qos_done(rq->q, rq);
1011                 if (rq->end_io(rq, error) == RQ_END_IO_FREE)
1012                         blk_mq_free_request(rq);
1013         } else {
1014                 blk_mq_free_request(rq);
1015         }
1016 }
1017 EXPORT_SYMBOL(__blk_mq_end_request);
1018
1019 void blk_mq_end_request(struct request *rq, blk_status_t error)
1020 {
1021         if (blk_update_request(rq, error, blk_rq_bytes(rq)))
1022                 BUG();
1023         __blk_mq_end_request(rq, error);
1024 }
1025 EXPORT_SYMBOL(blk_mq_end_request);
1026
1027 #define TAG_COMP_BATCH          32
1028
1029 static inline void blk_mq_flush_tag_batch(struct blk_mq_hw_ctx *hctx,
1030                                           int *tag_array, int nr_tags)
1031 {
1032         struct request_queue *q = hctx->queue;
1033
1034         /*
1035          * All requests should have been marked as RQF_MQ_INFLIGHT, so
1036          * update hctx->nr_active in batch
1037          */
1038         if (hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED)
1039                 __blk_mq_sub_active_requests(hctx, nr_tags);
1040
1041         blk_mq_put_tags(hctx->tags, tag_array, nr_tags);
1042         percpu_ref_put_many(&q->q_usage_counter, nr_tags);
1043 }
1044
1045 void blk_mq_end_request_batch(struct io_comp_batch *iob)
1046 {
1047         int tags[TAG_COMP_BATCH], nr_tags = 0;
1048         struct blk_mq_hw_ctx *cur_hctx = NULL;
1049         struct request *rq;
1050         u64 now = 0;
1051
1052         if (iob->need_ts)
1053                 now = ktime_get_ns();
1054
1055         while ((rq = rq_list_pop(&iob->req_list)) != NULL) {
1056                 prefetch(rq->bio);
1057                 prefetch(rq->rq_next);
1058
1059                 blk_complete_request(rq);
1060                 if (iob->need_ts)
1061                         __blk_mq_end_request_acct(rq, now);
1062
1063                 rq_qos_done(rq->q, rq);
1064
1065                 /*
1066                  * If end_io handler returns NONE, then it still has
1067                  * ownership of the request.
1068                  */
1069                 if (rq->end_io && rq->end_io(rq, 0) == RQ_END_IO_NONE)
1070                         continue;
1071
1072                 WRITE_ONCE(rq->state, MQ_RQ_IDLE);
1073                 if (!req_ref_put_and_test(rq))
1074                         continue;
1075
1076                 blk_crypto_free_request(rq);
1077                 blk_pm_mark_last_busy(rq);
1078
1079                 if (nr_tags == TAG_COMP_BATCH || cur_hctx != rq->mq_hctx) {
1080                         if (cur_hctx)
1081                                 blk_mq_flush_tag_batch(cur_hctx, tags, nr_tags);
1082                         nr_tags = 0;
1083                         cur_hctx = rq->mq_hctx;
1084                 }
1085                 tags[nr_tags++] = rq->tag;
1086         }
1087
1088         if (nr_tags)
1089                 blk_mq_flush_tag_batch(cur_hctx, tags, nr_tags);
1090 }
1091 EXPORT_SYMBOL_GPL(blk_mq_end_request_batch);
1092
1093 static void blk_complete_reqs(struct llist_head *list)
1094 {
1095         struct llist_node *entry = llist_reverse_order(llist_del_all(list));
1096         struct request *rq, *next;
1097
1098         llist_for_each_entry_safe(rq, next, entry, ipi_list)
1099                 rq->q->mq_ops->complete(rq);
1100 }
1101
1102 static __latent_entropy void blk_done_softirq(struct softirq_action *h)
1103 {
1104         blk_complete_reqs(this_cpu_ptr(&blk_cpu_done));
1105 }
1106
1107 static int blk_softirq_cpu_dead(unsigned int cpu)
1108 {
1109         blk_complete_reqs(&per_cpu(blk_cpu_done, cpu));
1110         return 0;
1111 }
1112
1113 static void __blk_mq_complete_request_remote(void *data)
1114 {
1115         __raise_softirq_irqoff(BLOCK_SOFTIRQ);
1116 }
1117
1118 static inline bool blk_mq_complete_need_ipi(struct request *rq)
1119 {
1120         int cpu = raw_smp_processor_id();
1121
1122         if (!IS_ENABLED(CONFIG_SMP) ||
1123             !test_bit(QUEUE_FLAG_SAME_COMP, &rq->q->queue_flags))
1124                 return false;
1125         /*
1126          * With force threaded interrupts enabled, raising softirq from an SMP
1127          * function call will always result in waking the ksoftirqd thread.
1128          * This is probably worse than completing the request on a different
1129          * cache domain.
1130          */
1131         if (force_irqthreads())
1132                 return false;
1133
1134         /* same CPU or cache domain?  Complete locally */
1135         if (cpu == rq->mq_ctx->cpu ||
1136             (!test_bit(QUEUE_FLAG_SAME_FORCE, &rq->q->queue_flags) &&
1137              cpus_share_cache(cpu, rq->mq_ctx->cpu)))
1138                 return false;
1139
1140         /* don't try to IPI to an offline CPU */
1141         return cpu_online(rq->mq_ctx->cpu);
1142 }
1143
1144 static void blk_mq_complete_send_ipi(struct request *rq)
1145 {
1146         struct llist_head *list;
1147         unsigned int cpu;
1148
1149         cpu = rq->mq_ctx->cpu;
1150         list = &per_cpu(blk_cpu_done, cpu);
1151         if (llist_add(&rq->ipi_list, list)) {
1152                 INIT_CSD(&rq->csd, __blk_mq_complete_request_remote, rq);
1153                 smp_call_function_single_async(cpu, &rq->csd);
1154         }
1155 }
1156
1157 static void blk_mq_raise_softirq(struct request *rq)
1158 {
1159         struct llist_head *list;
1160
1161         preempt_disable();
1162         list = this_cpu_ptr(&blk_cpu_done);
1163         if (llist_add(&rq->ipi_list, list))
1164                 raise_softirq(BLOCK_SOFTIRQ);
1165         preempt_enable();
1166 }
1167
1168 bool blk_mq_complete_request_remote(struct request *rq)
1169 {
1170         WRITE_ONCE(rq->state, MQ_RQ_COMPLETE);
1171
1172         /*
1173          * For request which hctx has only one ctx mapping,
1174          * or a polled request, always complete locally,
1175          * it's pointless to redirect the completion.
1176          */
1177         if (rq->mq_hctx->nr_ctx == 1 ||
1178                 rq->cmd_flags & REQ_POLLED)
1179                 return false;
1180
1181         if (blk_mq_complete_need_ipi(rq)) {
1182                 blk_mq_complete_send_ipi(rq);
1183                 return true;
1184         }
1185
1186         if (rq->q->nr_hw_queues == 1) {
1187                 blk_mq_raise_softirq(rq);
1188                 return true;
1189         }
1190         return false;
1191 }
1192 EXPORT_SYMBOL_GPL(blk_mq_complete_request_remote);
1193
1194 /**
1195  * blk_mq_complete_request - end I/O on a request
1196  * @rq:         the request being processed
1197  *
1198  * Description:
1199  *      Complete a request by scheduling the ->complete_rq operation.
1200  **/
1201 void blk_mq_complete_request(struct request *rq)
1202 {
1203         if (!blk_mq_complete_request_remote(rq))
1204                 rq->q->mq_ops->complete(rq);
1205 }
1206 EXPORT_SYMBOL(blk_mq_complete_request);
1207
1208 /**
1209  * blk_mq_start_request - Start processing a request
1210  * @rq: Pointer to request to be started
1211  *
1212  * Function used by device drivers to notify the block layer that a request
1213  * is going to be processed now, so blk layer can do proper initializations
1214  * such as starting the timeout timer.
1215  */
1216 void blk_mq_start_request(struct request *rq)
1217 {
1218         struct request_queue *q = rq->q;
1219
1220         trace_block_rq_issue(rq);
1221
1222         if (test_bit(QUEUE_FLAG_STATS, &q->queue_flags)) {
1223                 rq->io_start_time_ns = ktime_get_ns();
1224                 rq->stats_sectors = blk_rq_sectors(rq);
1225                 rq->rq_flags |= RQF_STATS;
1226                 rq_qos_issue(q, rq);
1227         }
1228
1229         WARN_ON_ONCE(blk_mq_rq_state(rq) != MQ_RQ_IDLE);
1230
1231         blk_add_timer(rq);
1232         WRITE_ONCE(rq->state, MQ_RQ_IN_FLIGHT);
1233
1234 #ifdef CONFIG_BLK_DEV_INTEGRITY
1235         if (blk_integrity_rq(rq) && req_op(rq) == REQ_OP_WRITE)
1236                 q->integrity.profile->prepare_fn(rq);
1237 #endif
1238         if (rq->bio && rq->bio->bi_opf & REQ_POLLED)
1239                 WRITE_ONCE(rq->bio->bi_cookie, blk_rq_to_qc(rq));
1240 }
1241 EXPORT_SYMBOL(blk_mq_start_request);
1242
1243 /*
1244  * Allow 2x BLK_MAX_REQUEST_COUNT requests on plug queue for multiple
1245  * queues. This is important for md arrays to benefit from merging
1246  * requests.
1247  */
1248 static inline unsigned short blk_plug_max_rq_count(struct blk_plug *plug)
1249 {
1250         if (plug->multiple_queues)
1251                 return BLK_MAX_REQUEST_COUNT * 2;
1252         return BLK_MAX_REQUEST_COUNT;
1253 }
1254
1255 static void blk_add_rq_to_plug(struct blk_plug *plug, struct request *rq)
1256 {
1257         struct request *last = rq_list_peek(&plug->mq_list);
1258
1259         if (!plug->rq_count) {
1260                 trace_block_plug(rq->q);
1261         } else if (plug->rq_count >= blk_plug_max_rq_count(plug) ||
1262                    (!blk_queue_nomerges(rq->q) &&
1263                     blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
1264                 blk_mq_flush_plug_list(plug, false);
1265                 last = NULL;
1266                 trace_block_plug(rq->q);
1267         }
1268
1269         if (!plug->multiple_queues && last && last->q != rq->q)
1270                 plug->multiple_queues = true;
1271         if (!plug->has_elevator && (rq->rq_flags & RQF_ELV))
1272                 plug->has_elevator = true;
1273         rq->rq_next = NULL;
1274         rq_list_add(&plug->mq_list, rq);
1275         plug->rq_count++;
1276 }
1277
1278 /**
1279  * blk_execute_rq_nowait - insert a request to I/O scheduler for execution
1280  * @rq:         request to insert
1281  * @at_head:    insert request at head or tail of queue
1282  *
1283  * Description:
1284  *    Insert a fully prepared request at the back of the I/O scheduler queue
1285  *    for execution.  Don't wait for completion.
1286  *
1287  * Note:
1288  *    This function will invoke @done directly if the queue is dead.
1289  */
1290 void blk_execute_rq_nowait(struct request *rq, bool at_head)
1291 {
1292         WARN_ON(irqs_disabled());
1293         WARN_ON(!blk_rq_is_passthrough(rq));
1294
1295         blk_account_io_start(rq);
1296
1297         /*
1298          * As plugging can be enabled for passthrough requests on a zoned
1299          * device, directly accessing the plug instead of using blk_mq_plug()
1300          * should not have any consequences.
1301          */
1302         if (current->plug)
1303                 blk_add_rq_to_plug(current->plug, rq);
1304         else
1305                 blk_mq_sched_insert_request(rq, at_head, true, false);
1306 }
1307 EXPORT_SYMBOL_GPL(blk_execute_rq_nowait);
1308
1309 struct blk_rq_wait {
1310         struct completion done;
1311         blk_status_t ret;
1312 };
1313
1314 static enum rq_end_io_ret blk_end_sync_rq(struct request *rq, blk_status_t ret)
1315 {
1316         struct blk_rq_wait *wait = rq->end_io_data;
1317
1318         wait->ret = ret;
1319         complete(&wait->done);
1320         return RQ_END_IO_NONE;
1321 }
1322
1323 bool blk_rq_is_poll(struct request *rq)
1324 {
1325         if (!rq->mq_hctx)
1326                 return false;
1327         if (rq->mq_hctx->type != HCTX_TYPE_POLL)
1328                 return false;
1329         if (WARN_ON_ONCE(!rq->bio))
1330                 return false;
1331         return true;
1332 }
1333 EXPORT_SYMBOL_GPL(blk_rq_is_poll);
1334
1335 static void blk_rq_poll_completion(struct request *rq, struct completion *wait)
1336 {
1337         do {
1338                 bio_poll(rq->bio, NULL, 0);
1339                 cond_resched();
1340         } while (!completion_done(wait));
1341 }
1342
1343 /**
1344  * blk_execute_rq - insert a request into queue for execution
1345  * @rq:         request to insert
1346  * @at_head:    insert request at head or tail of queue
1347  *
1348  * Description:
1349  *    Insert a fully prepared request at the back of the I/O scheduler queue
1350  *    for execution and wait for completion.
1351  * Return: The blk_status_t result provided to blk_mq_end_request().
1352  */
1353 blk_status_t blk_execute_rq(struct request *rq, bool at_head)
1354 {
1355         struct blk_rq_wait wait = {
1356                 .done = COMPLETION_INITIALIZER_ONSTACK(wait.done),
1357         };
1358
1359         WARN_ON(irqs_disabled());
1360         WARN_ON(!blk_rq_is_passthrough(rq));
1361
1362         rq->end_io_data = &wait;
1363         rq->end_io = blk_end_sync_rq;
1364
1365         blk_account_io_start(rq);
1366         blk_mq_sched_insert_request(rq, at_head, true, false);
1367
1368         if (blk_rq_is_poll(rq)) {
1369                 blk_rq_poll_completion(rq, &wait.done);
1370         } else {
1371                 /*
1372                  * Prevent hang_check timer from firing at us during very long
1373                  * I/O
1374                  */
1375                 unsigned long hang_check = sysctl_hung_task_timeout_secs;
1376
1377                 if (hang_check)
1378                         while (!wait_for_completion_io_timeout(&wait.done,
1379                                         hang_check * (HZ/2)))
1380                                 ;
1381                 else
1382                         wait_for_completion_io(&wait.done);
1383         }
1384
1385         return wait.ret;
1386 }
1387 EXPORT_SYMBOL(blk_execute_rq);
1388
1389 static void __blk_mq_requeue_request(struct request *rq)
1390 {
1391         struct request_queue *q = rq->q;
1392
1393         blk_mq_put_driver_tag(rq);
1394
1395         trace_block_rq_requeue(rq);
1396         rq_qos_requeue(q, rq);
1397
1398         if (blk_mq_request_started(rq)) {
1399                 WRITE_ONCE(rq->state, MQ_RQ_IDLE);
1400                 rq->rq_flags &= ~RQF_TIMED_OUT;
1401         }
1402 }
1403
1404 void blk_mq_requeue_request(struct request *rq, bool kick_requeue_list)
1405 {
1406         __blk_mq_requeue_request(rq);
1407
1408         /* this request will be re-inserted to io scheduler queue */
1409         blk_mq_sched_requeue_request(rq);
1410
1411         blk_mq_add_to_requeue_list(rq, true, kick_requeue_list);
1412 }
1413 EXPORT_SYMBOL(blk_mq_requeue_request);
1414
1415 static void blk_mq_requeue_work(struct work_struct *work)
1416 {
1417         struct request_queue *q =
1418                 container_of(work, struct request_queue, requeue_work.work);
1419         LIST_HEAD(rq_list);
1420         struct request *rq, *next;
1421
1422         spin_lock_irq(&q->requeue_lock);
1423         list_splice_init(&q->requeue_list, &rq_list);
1424         spin_unlock_irq(&q->requeue_lock);
1425
1426         list_for_each_entry_safe(rq, next, &rq_list, queuelist) {
1427                 if (!(rq->rq_flags & (RQF_SOFTBARRIER | RQF_DONTPREP)))
1428                         continue;
1429
1430                 rq->rq_flags &= ~RQF_SOFTBARRIER;
1431                 list_del_init(&rq->queuelist);
1432                 /*
1433                  * If RQF_DONTPREP, rq has contained some driver specific
1434                  * data, so insert it to hctx dispatch list to avoid any
1435                  * merge.
1436                  */
1437                 if (rq->rq_flags & RQF_DONTPREP)
1438                         blk_mq_request_bypass_insert(rq, false, false);
1439                 else
1440                         blk_mq_sched_insert_request(rq, true, false, false);
1441         }
1442
1443         while (!list_empty(&rq_list)) {
1444                 rq = list_entry(rq_list.next, struct request, queuelist);
1445                 list_del_init(&rq->queuelist);
1446                 blk_mq_sched_insert_request(rq, false, false, false);
1447         }
1448
1449         blk_mq_run_hw_queues(q, false);
1450 }
1451
1452 void blk_mq_add_to_requeue_list(struct request *rq, bool at_head,
1453                                 bool kick_requeue_list)
1454 {
1455         struct request_queue *q = rq->q;
1456         unsigned long flags;
1457
1458         /*
1459          * We abuse this flag that is otherwise used by the I/O scheduler to
1460          * request head insertion from the workqueue.
1461          */
1462         BUG_ON(rq->rq_flags & RQF_SOFTBARRIER);
1463
1464         spin_lock_irqsave(&q->requeue_lock, flags);
1465         if (at_head) {
1466                 rq->rq_flags |= RQF_SOFTBARRIER;
1467                 list_add(&rq->queuelist, &q->requeue_list);
1468         } else {
1469                 list_add_tail(&rq->queuelist, &q->requeue_list);
1470         }
1471         spin_unlock_irqrestore(&q->requeue_lock, flags);
1472
1473         if (kick_requeue_list)
1474                 blk_mq_kick_requeue_list(q);
1475 }
1476
1477 void blk_mq_kick_requeue_list(struct request_queue *q)
1478 {
1479         kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND, &q->requeue_work, 0);
1480 }
1481 EXPORT_SYMBOL(blk_mq_kick_requeue_list);
1482
1483 void blk_mq_delay_kick_requeue_list(struct request_queue *q,
1484                                     unsigned long msecs)
1485 {
1486         kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND, &q->requeue_work,
1487                                     msecs_to_jiffies(msecs));
1488 }
1489 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list);
1490
1491 static bool blk_mq_rq_inflight(struct request *rq, void *priv)
1492 {
1493         /*
1494          * If we find a request that isn't idle we know the queue is busy
1495          * as it's checked in the iter.
1496          * Return false to stop the iteration.
1497          */
1498         if (blk_mq_request_started(rq)) {
1499                 bool *busy = priv;
1500
1501                 *busy = true;
1502                 return false;
1503         }
1504
1505         return true;
1506 }
1507
1508 bool blk_mq_queue_inflight(struct request_queue *q)
1509 {
1510         bool busy = false;
1511
1512         blk_mq_queue_tag_busy_iter(q, blk_mq_rq_inflight, &busy);
1513         return busy;
1514 }
1515 EXPORT_SYMBOL_GPL(blk_mq_queue_inflight);
1516
1517 static void blk_mq_rq_timed_out(struct request *req)
1518 {
1519         req->rq_flags |= RQF_TIMED_OUT;
1520         if (req->q->mq_ops->timeout) {
1521                 enum blk_eh_timer_return ret;
1522
1523                 ret = req->q->mq_ops->timeout(req);
1524                 if (ret == BLK_EH_DONE)
1525                         return;
1526                 WARN_ON_ONCE(ret != BLK_EH_RESET_TIMER);
1527         }
1528
1529         blk_add_timer(req);
1530 }
1531
1532 static bool blk_mq_req_expired(struct request *rq, unsigned long *next)
1533 {
1534         unsigned long deadline;
1535
1536         if (blk_mq_rq_state(rq) != MQ_RQ_IN_FLIGHT)
1537                 return false;
1538         if (rq->rq_flags & RQF_TIMED_OUT)
1539                 return false;
1540
1541         deadline = READ_ONCE(rq->deadline);
1542         if (time_after_eq(jiffies, deadline))
1543                 return true;
1544
1545         if (*next == 0)
1546                 *next = deadline;
1547         else if (time_after(*next, deadline))
1548                 *next = deadline;
1549         return false;
1550 }
1551
1552 void blk_mq_put_rq_ref(struct request *rq)
1553 {
1554         if (is_flush_rq(rq)) {
1555                 if (rq->end_io(rq, 0) == RQ_END_IO_FREE)
1556                         blk_mq_free_request(rq);
1557         } else if (req_ref_put_and_test(rq)) {
1558                 __blk_mq_free_request(rq);
1559         }
1560 }
1561
1562 static bool blk_mq_check_expired(struct request *rq, void *priv)
1563 {
1564         unsigned long *next = priv;
1565
1566         /*
1567          * blk_mq_queue_tag_busy_iter() has locked the request, so it cannot
1568          * be reallocated underneath the timeout handler's processing, then
1569          * the expire check is reliable. If the request is not expired, then
1570          * it was completed and reallocated as a new request after returning
1571          * from blk_mq_check_expired().
1572          */
1573         if (blk_mq_req_expired(rq, next))
1574                 blk_mq_rq_timed_out(rq);
1575         return true;
1576 }
1577
1578 static void blk_mq_timeout_work(struct work_struct *work)
1579 {
1580         struct request_queue *q =
1581                 container_of(work, struct request_queue, timeout_work);
1582         unsigned long next = 0;
1583         struct blk_mq_hw_ctx *hctx;
1584         unsigned long i;
1585
1586         /* A deadlock might occur if a request is stuck requiring a
1587          * timeout at the same time a queue freeze is waiting
1588          * completion, since the timeout code would not be able to
1589          * acquire the queue reference here.
1590          *
1591          * That's why we don't use blk_queue_enter here; instead, we use
1592          * percpu_ref_tryget directly, because we need to be able to
1593          * obtain a reference even in the short window between the queue
1594          * starting to freeze, by dropping the first reference in
1595          * blk_freeze_queue_start, and the moment the last request is
1596          * consumed, marked by the instant q_usage_counter reaches
1597          * zero.
1598          */
1599         if (!percpu_ref_tryget(&q->q_usage_counter))
1600                 return;
1601
1602         blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &next);
1603
1604         if (next != 0) {
1605                 mod_timer(&q->timeout, next);
1606         } else {
1607                 /*
1608                  * Request timeouts are handled as a forward rolling timer. If
1609                  * we end up here it means that no requests are pending and
1610                  * also that no request has been pending for a while. Mark
1611                  * each hctx as idle.
1612                  */
1613                 queue_for_each_hw_ctx(q, hctx, i) {
1614                         /* the hctx may be unmapped, so check it here */
1615                         if (blk_mq_hw_queue_mapped(hctx))
1616                                 blk_mq_tag_idle(hctx);
1617                 }
1618         }
1619         blk_queue_exit(q);
1620 }
1621
1622 struct flush_busy_ctx_data {
1623         struct blk_mq_hw_ctx *hctx;
1624         struct list_head *list;
1625 };
1626
1627 static bool flush_busy_ctx(struct sbitmap *sb, unsigned int bitnr, void *data)
1628 {
1629         struct flush_busy_ctx_data *flush_data = data;
1630         struct blk_mq_hw_ctx *hctx = flush_data->hctx;
1631         struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
1632         enum hctx_type type = hctx->type;
1633
1634         spin_lock(&ctx->lock);
1635         list_splice_tail_init(&ctx->rq_lists[type], flush_data->list);
1636         sbitmap_clear_bit(sb, bitnr);
1637         spin_unlock(&ctx->lock);
1638         return true;
1639 }
1640
1641 /*
1642  * Process software queues that have been marked busy, splicing them
1643  * to the for-dispatch
1644  */
1645 void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list)
1646 {
1647         struct flush_busy_ctx_data data = {
1648                 .hctx = hctx,
1649                 .list = list,
1650         };
1651
1652         sbitmap_for_each_set(&hctx->ctx_map, flush_busy_ctx, &data);
1653 }
1654 EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs);
1655
1656 struct dispatch_rq_data {
1657         struct blk_mq_hw_ctx *hctx;
1658         struct request *rq;
1659 };
1660
1661 static bool dispatch_rq_from_ctx(struct sbitmap *sb, unsigned int bitnr,
1662                 void *data)
1663 {
1664         struct dispatch_rq_data *dispatch_data = data;
1665         struct blk_mq_hw_ctx *hctx = dispatch_data->hctx;
1666         struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
1667         enum hctx_type type = hctx->type;
1668
1669         spin_lock(&ctx->lock);
1670         if (!list_empty(&ctx->rq_lists[type])) {
1671                 dispatch_data->rq = list_entry_rq(ctx->rq_lists[type].next);
1672                 list_del_init(&dispatch_data->rq->queuelist);
1673                 if (list_empty(&ctx->rq_lists[type]))
1674                         sbitmap_clear_bit(sb, bitnr);
1675         }
1676         spin_unlock(&ctx->lock);
1677
1678         return !dispatch_data->rq;
1679 }
1680
1681 struct request *blk_mq_dequeue_from_ctx(struct blk_mq_hw_ctx *hctx,
1682                                         struct blk_mq_ctx *start)
1683 {
1684         unsigned off = start ? start->index_hw[hctx->type] : 0;
1685         struct dispatch_rq_data data = {
1686                 .hctx = hctx,
1687                 .rq   = NULL,
1688         };
1689
1690         __sbitmap_for_each_set(&hctx->ctx_map, off,
1691                                dispatch_rq_from_ctx, &data);
1692
1693         return data.rq;
1694 }
1695
1696 static bool __blk_mq_alloc_driver_tag(struct request *rq)
1697 {
1698         struct sbitmap_queue *bt = &rq->mq_hctx->tags->bitmap_tags;
1699         unsigned int tag_offset = rq->mq_hctx->tags->nr_reserved_tags;
1700         int tag;
1701
1702         blk_mq_tag_busy(rq->mq_hctx);
1703
1704         if (blk_mq_tag_is_reserved(rq->mq_hctx->sched_tags, rq->internal_tag)) {
1705                 bt = &rq->mq_hctx->tags->breserved_tags;
1706                 tag_offset = 0;
1707         } else {
1708                 if (!hctx_may_queue(rq->mq_hctx, bt))
1709                         return false;
1710         }
1711
1712         tag = __sbitmap_queue_get(bt);
1713         if (tag == BLK_MQ_NO_TAG)
1714                 return false;
1715
1716         rq->tag = tag + tag_offset;
1717         return true;
1718 }
1719
1720 bool __blk_mq_get_driver_tag(struct blk_mq_hw_ctx *hctx, struct request *rq)
1721 {
1722         if (rq->tag == BLK_MQ_NO_TAG && !__blk_mq_alloc_driver_tag(rq))
1723                 return false;
1724
1725         if ((hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED) &&
1726                         !(rq->rq_flags & RQF_MQ_INFLIGHT)) {
1727                 rq->rq_flags |= RQF_MQ_INFLIGHT;
1728                 __blk_mq_inc_active_requests(hctx);
1729         }
1730         hctx->tags->rqs[rq->tag] = rq;
1731         return true;
1732 }
1733
1734 static int blk_mq_dispatch_wake(wait_queue_entry_t *wait, unsigned mode,
1735                                 int flags, void *key)
1736 {
1737         struct blk_mq_hw_ctx *hctx;
1738
1739         hctx = container_of(wait, struct blk_mq_hw_ctx, dispatch_wait);
1740
1741         spin_lock(&hctx->dispatch_wait_lock);
1742         if (!list_empty(&wait->entry)) {
1743                 struct sbitmap_queue *sbq;
1744
1745                 list_del_init(&wait->entry);
1746                 sbq = &hctx->tags->bitmap_tags;
1747                 atomic_dec(&sbq->ws_active);
1748         }
1749         spin_unlock(&hctx->dispatch_wait_lock);
1750
1751         blk_mq_run_hw_queue(hctx, true);
1752         return 1;
1753 }
1754
1755 /*
1756  * Mark us waiting for a tag. For shared tags, this involves hooking us into
1757  * the tag wakeups. For non-shared tags, we can simply mark us needing a
1758  * restart. For both cases, take care to check the condition again after
1759  * marking us as waiting.
1760  */
1761 static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx *hctx,
1762                                  struct request *rq)
1763 {
1764         struct sbitmap_queue *sbq = &hctx->tags->bitmap_tags;
1765         struct wait_queue_head *wq;
1766         wait_queue_entry_t *wait;
1767         bool ret;
1768
1769         if (!(hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED)) {
1770                 blk_mq_sched_mark_restart_hctx(hctx);
1771
1772                 /*
1773                  * It's possible that a tag was freed in the window between the
1774                  * allocation failure and adding the hardware queue to the wait
1775                  * queue.
1776                  *
1777                  * Don't clear RESTART here, someone else could have set it.
1778                  * At most this will cost an extra queue run.
1779                  */
1780                 return blk_mq_get_driver_tag(rq);
1781         }
1782
1783         wait = &hctx->dispatch_wait;
1784         if (!list_empty_careful(&wait->entry))
1785                 return false;
1786
1787         wq = &bt_wait_ptr(sbq, hctx)->wait;
1788
1789         spin_lock_irq(&wq->lock);
1790         spin_lock(&hctx->dispatch_wait_lock);
1791         if (!list_empty(&wait->entry)) {
1792                 spin_unlock(&hctx->dispatch_wait_lock);
1793                 spin_unlock_irq(&wq->lock);
1794                 return false;
1795         }
1796
1797         atomic_inc(&sbq->ws_active);
1798         wait->flags &= ~WQ_FLAG_EXCLUSIVE;
1799         __add_wait_queue(wq, wait);
1800
1801         /*
1802          * It's possible that a tag was freed in the window between the
1803          * allocation failure and adding the hardware queue to the wait
1804          * queue.
1805          */
1806         ret = blk_mq_get_driver_tag(rq);
1807         if (!ret) {
1808                 spin_unlock(&hctx->dispatch_wait_lock);
1809                 spin_unlock_irq(&wq->lock);
1810                 return false;
1811         }
1812
1813         /*
1814          * We got a tag, remove ourselves from the wait queue to ensure
1815          * someone else gets the wakeup.
1816          */
1817         list_del_init(&wait->entry);
1818         atomic_dec(&sbq->ws_active);
1819         spin_unlock(&hctx->dispatch_wait_lock);
1820         spin_unlock_irq(&wq->lock);
1821
1822         return true;
1823 }
1824
1825 #define BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT  8
1826 #define BLK_MQ_DISPATCH_BUSY_EWMA_FACTOR  4
1827 /*
1828  * Update dispatch busy with the Exponential Weighted Moving Average(EWMA):
1829  * - EWMA is one simple way to compute running average value
1830  * - weight(7/8 and 1/8) is applied so that it can decrease exponentially
1831  * - take 4 as factor for avoiding to get too small(0) result, and this
1832  *   factor doesn't matter because EWMA decreases exponentially
1833  */
1834 static void blk_mq_update_dispatch_busy(struct blk_mq_hw_ctx *hctx, bool busy)
1835 {
1836         unsigned int ewma;
1837
1838         ewma = hctx->dispatch_busy;
1839
1840         if (!ewma && !busy)
1841                 return;
1842
1843         ewma *= BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT - 1;
1844         if (busy)
1845                 ewma += 1 << BLK_MQ_DISPATCH_BUSY_EWMA_FACTOR;
1846         ewma /= BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT;
1847
1848         hctx->dispatch_busy = ewma;
1849 }
1850
1851 #define BLK_MQ_RESOURCE_DELAY   3               /* ms units */
1852
1853 static void blk_mq_handle_dev_resource(struct request *rq,
1854                                        struct list_head *list)
1855 {
1856         struct request *next =
1857                 list_first_entry_or_null(list, struct request, queuelist);
1858
1859         /*
1860          * If an I/O scheduler has been configured and we got a driver tag for
1861          * the next request already, free it.
1862          */
1863         if (next)
1864                 blk_mq_put_driver_tag(next);
1865
1866         list_add(&rq->queuelist, list);
1867         __blk_mq_requeue_request(rq);
1868 }
1869
1870 static void blk_mq_handle_zone_resource(struct request *rq,
1871                                         struct list_head *zone_list)
1872 {
1873         /*
1874          * If we end up here it is because we cannot dispatch a request to a
1875          * specific zone due to LLD level zone-write locking or other zone
1876          * related resource not being available. In this case, set the request
1877          * aside in zone_list for retrying it later.
1878          */
1879         list_add(&rq->queuelist, zone_list);
1880         __blk_mq_requeue_request(rq);
1881 }
1882
1883 enum prep_dispatch {
1884         PREP_DISPATCH_OK,
1885         PREP_DISPATCH_NO_TAG,
1886         PREP_DISPATCH_NO_BUDGET,
1887 };
1888
1889 static enum prep_dispatch blk_mq_prep_dispatch_rq(struct request *rq,
1890                                                   bool need_budget)
1891 {
1892         struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
1893         int budget_token = -1;
1894
1895         if (need_budget) {
1896                 budget_token = blk_mq_get_dispatch_budget(rq->q);
1897                 if (budget_token < 0) {
1898                         blk_mq_put_driver_tag(rq);
1899                         return PREP_DISPATCH_NO_BUDGET;
1900                 }
1901                 blk_mq_set_rq_budget_token(rq, budget_token);
1902         }
1903
1904         if (!blk_mq_get_driver_tag(rq)) {
1905                 /*
1906                  * The initial allocation attempt failed, so we need to
1907                  * rerun the hardware queue when a tag is freed. The
1908                  * waitqueue takes care of that. If the queue is run
1909                  * before we add this entry back on the dispatch list,
1910                  * we'll re-run it below.
1911                  */
1912                 if (!blk_mq_mark_tag_wait(hctx, rq)) {
1913                         /*
1914                          * All budgets not got from this function will be put
1915                          * together during handling partial dispatch
1916                          */
1917                         if (need_budget)
1918                                 blk_mq_put_dispatch_budget(rq->q, budget_token);
1919                         return PREP_DISPATCH_NO_TAG;
1920                 }
1921         }
1922
1923         return PREP_DISPATCH_OK;
1924 }
1925
1926 /* release all allocated budgets before calling to blk_mq_dispatch_rq_list */
1927 static void blk_mq_release_budgets(struct request_queue *q,
1928                 struct list_head *list)
1929 {
1930         struct request *rq;
1931
1932         list_for_each_entry(rq, list, queuelist) {
1933                 int budget_token = blk_mq_get_rq_budget_token(rq);
1934
1935                 if (budget_token >= 0)
1936                         blk_mq_put_dispatch_budget(q, budget_token);
1937         }
1938 }
1939
1940 /*
1941  * Returns true if we did some work AND can potentially do more.
1942  */
1943 bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list,
1944                              unsigned int nr_budgets)
1945 {
1946         enum prep_dispatch prep;
1947         struct request_queue *q = hctx->queue;
1948         struct request *rq, *nxt;
1949         int errors, queued;
1950         blk_status_t ret = BLK_STS_OK;
1951         LIST_HEAD(zone_list);
1952         bool needs_resource = false;
1953
1954         if (list_empty(list))
1955                 return false;
1956
1957         /*
1958          * Now process all the entries, sending them to the driver.
1959          */
1960         errors = queued = 0;
1961         do {
1962                 struct blk_mq_queue_data bd;
1963
1964                 rq = list_first_entry(list, struct request, queuelist);
1965
1966                 WARN_ON_ONCE(hctx != rq->mq_hctx);
1967                 prep = blk_mq_prep_dispatch_rq(rq, !nr_budgets);
1968                 if (prep != PREP_DISPATCH_OK)
1969                         break;
1970
1971                 list_del_init(&rq->queuelist);
1972
1973                 bd.rq = rq;
1974
1975                 /*
1976                  * Flag last if we have no more requests, or if we have more
1977                  * but can't assign a driver tag to it.
1978                  */
1979                 if (list_empty(list))
1980                         bd.last = true;
1981                 else {
1982                         nxt = list_first_entry(list, struct request, queuelist);
1983                         bd.last = !blk_mq_get_driver_tag(nxt);
1984                 }
1985
1986                 /*
1987                  * once the request is queued to lld, no need to cover the
1988                  * budget any more
1989                  */
1990                 if (nr_budgets)
1991                         nr_budgets--;
1992                 ret = q->mq_ops->queue_rq(hctx, &bd);
1993                 switch (ret) {
1994                 case BLK_STS_OK:
1995                         queued++;
1996                         break;
1997                 case BLK_STS_RESOURCE:
1998                         needs_resource = true;
1999                         fallthrough;
2000                 case BLK_STS_DEV_RESOURCE:
2001                         blk_mq_handle_dev_resource(rq, list);
2002                         goto out;
2003                 case BLK_STS_ZONE_RESOURCE:
2004                         /*
2005                          * Move the request to zone_list and keep going through
2006                          * the dispatch list to find more requests the drive can
2007                          * accept.
2008                          */
2009                         blk_mq_handle_zone_resource(rq, &zone_list);
2010                         needs_resource = true;
2011                         break;
2012                 default:
2013                         errors++;
2014                         blk_mq_end_request(rq, ret);
2015                 }
2016         } while (!list_empty(list));
2017 out:
2018         if (!list_empty(&zone_list))
2019                 list_splice_tail_init(&zone_list, list);
2020
2021         /* If we didn't flush the entire list, we could have told the driver
2022          * there was more coming, but that turned out to be a lie.
2023          */
2024         if ((!list_empty(list) || errors || needs_resource ||
2025              ret == BLK_STS_DEV_RESOURCE) && q->mq_ops->commit_rqs && queued)
2026                 q->mq_ops->commit_rqs(hctx);
2027         /*
2028          * Any items that need requeuing? Stuff them into hctx->dispatch,
2029          * that is where we will continue on next queue run.
2030          */
2031         if (!list_empty(list)) {
2032                 bool needs_restart;
2033                 /* For non-shared tags, the RESTART check will suffice */
2034                 bool no_tag = prep == PREP_DISPATCH_NO_TAG &&
2035                         (hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED);
2036
2037                 if (nr_budgets)
2038                         blk_mq_release_budgets(q, list);
2039
2040                 spin_lock(&hctx->lock);
2041                 list_splice_tail_init(list, &hctx->dispatch);
2042                 spin_unlock(&hctx->lock);
2043
2044                 /*
2045                  * Order adding requests to hctx->dispatch and checking
2046                  * SCHED_RESTART flag. The pair of this smp_mb() is the one
2047                  * in blk_mq_sched_restart(). Avoid restart code path to
2048                  * miss the new added requests to hctx->dispatch, meantime
2049                  * SCHED_RESTART is observed here.
2050                  */
2051                 smp_mb();
2052
2053                 /*
2054                  * If SCHED_RESTART was set by the caller of this function and
2055                  * it is no longer set that means that it was cleared by another
2056                  * thread and hence that a queue rerun is needed.
2057                  *
2058                  * If 'no_tag' is set, that means that we failed getting
2059                  * a driver tag with an I/O scheduler attached. If our dispatch
2060                  * waitqueue is no longer active, ensure that we run the queue
2061                  * AFTER adding our entries back to the list.
2062                  *
2063                  * If no I/O scheduler has been configured it is possible that
2064                  * the hardware queue got stopped and restarted before requests
2065                  * were pushed back onto the dispatch list. Rerun the queue to
2066                  * avoid starvation. Notes:
2067                  * - blk_mq_run_hw_queue() checks whether or not a queue has
2068                  *   been stopped before rerunning a queue.
2069                  * - Some but not all block drivers stop a queue before
2070                  *   returning BLK_STS_RESOURCE. Two exceptions are scsi-mq
2071                  *   and dm-rq.
2072                  *
2073                  * If driver returns BLK_STS_RESOURCE and SCHED_RESTART
2074                  * bit is set, run queue after a delay to avoid IO stalls
2075                  * that could otherwise occur if the queue is idle.  We'll do
2076                  * similar if we couldn't get budget or couldn't lock a zone
2077                  * and SCHED_RESTART is set.
2078                  */
2079                 needs_restart = blk_mq_sched_needs_restart(hctx);
2080                 if (prep == PREP_DISPATCH_NO_BUDGET)
2081                         needs_resource = true;
2082                 if (!needs_restart ||
2083                     (no_tag && list_empty_careful(&hctx->dispatch_wait.entry)))
2084                         blk_mq_run_hw_queue(hctx, true);
2085                 else if (needs_resource)
2086                         blk_mq_delay_run_hw_queue(hctx, BLK_MQ_RESOURCE_DELAY);
2087
2088                 blk_mq_update_dispatch_busy(hctx, true);
2089                 return false;
2090         } else
2091                 blk_mq_update_dispatch_busy(hctx, false);
2092
2093         return (queued + errors) != 0;
2094 }
2095
2096 /**
2097  * __blk_mq_run_hw_queue - Run a hardware queue.
2098  * @hctx: Pointer to the hardware queue to run.
2099  *
2100  * Send pending requests to the hardware.
2101  */
2102 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
2103 {
2104         /*
2105          * We can't run the queue inline with ints disabled. Ensure that
2106          * we catch bad users of this early.
2107          */
2108         WARN_ON_ONCE(in_interrupt());
2109
2110         blk_mq_run_dispatch_ops(hctx->queue,
2111                         blk_mq_sched_dispatch_requests(hctx));
2112 }
2113
2114 static inline int blk_mq_first_mapped_cpu(struct blk_mq_hw_ctx *hctx)
2115 {
2116         int cpu = cpumask_first_and(hctx->cpumask, cpu_online_mask);
2117
2118         if (cpu >= nr_cpu_ids)
2119                 cpu = cpumask_first(hctx->cpumask);
2120         return cpu;
2121 }
2122
2123 /*
2124  * It'd be great if the workqueue API had a way to pass
2125  * in a mask and had some smarts for more clever placement.
2126  * For now we just round-robin here, switching for every
2127  * BLK_MQ_CPU_WORK_BATCH queued items.
2128  */
2129 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
2130 {
2131         bool tried = false;
2132         int next_cpu = hctx->next_cpu;
2133
2134         if (hctx->queue->nr_hw_queues == 1)
2135                 return WORK_CPU_UNBOUND;
2136
2137         if (--hctx->next_cpu_batch <= 0) {
2138 select_cpu:
2139                 next_cpu = cpumask_next_and(next_cpu, hctx->cpumask,
2140                                 cpu_online_mask);
2141                 if (next_cpu >= nr_cpu_ids)
2142                         next_cpu = blk_mq_first_mapped_cpu(hctx);
2143                 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
2144         }
2145
2146         /*
2147          * Do unbound schedule if we can't find a online CPU for this hctx,
2148          * and it should only happen in the path of handling CPU DEAD.
2149          */
2150         if (!cpu_online(next_cpu)) {
2151                 if (!tried) {
2152                         tried = true;
2153                         goto select_cpu;
2154                 }
2155
2156                 /*
2157                  * Make sure to re-select CPU next time once after CPUs
2158                  * in hctx->cpumask become online again.
2159                  */
2160                 hctx->next_cpu = next_cpu;
2161                 hctx->next_cpu_batch = 1;
2162                 return WORK_CPU_UNBOUND;
2163         }
2164
2165         hctx->next_cpu = next_cpu;
2166         return next_cpu;
2167 }
2168
2169 /**
2170  * __blk_mq_delay_run_hw_queue - Run (or schedule to run) a hardware queue.
2171  * @hctx: Pointer to the hardware queue to run.
2172  * @async: If we want to run the queue asynchronously.
2173  * @msecs: Milliseconds of delay to wait before running the queue.
2174  *
2175  * If !@async, try to run the queue now. Else, run the queue asynchronously and
2176  * with a delay of @msecs.
2177  */
2178 static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async,
2179                                         unsigned long msecs)
2180 {
2181         if (unlikely(blk_mq_hctx_stopped(hctx)))
2182                 return;
2183
2184         if (!async && !(hctx->flags & BLK_MQ_F_BLOCKING)) {
2185                 if (cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask)) {
2186                         __blk_mq_run_hw_queue(hctx);
2187                         return;
2188                 }
2189         }
2190
2191         kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx), &hctx->run_work,
2192                                     msecs_to_jiffies(msecs));
2193 }
2194
2195 /**
2196  * blk_mq_delay_run_hw_queue - Run a hardware queue asynchronously.
2197  * @hctx: Pointer to the hardware queue to run.
2198  * @msecs: Milliseconds of delay to wait before running the queue.
2199  *
2200  * Run a hardware queue asynchronously with a delay of @msecs.
2201  */
2202 void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
2203 {
2204         __blk_mq_delay_run_hw_queue(hctx, true, msecs);
2205 }
2206 EXPORT_SYMBOL(blk_mq_delay_run_hw_queue);
2207
2208 /**
2209  * blk_mq_run_hw_queue - Start to run a hardware queue.
2210  * @hctx: Pointer to the hardware queue to run.
2211  * @async: If we want to run the queue asynchronously.
2212  *
2213  * Check if the request queue is not in a quiesced state and if there are
2214  * pending requests to be sent. If this is true, run the queue to send requests
2215  * to hardware.
2216  */
2217 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
2218 {
2219         bool need_run;
2220
2221         /*
2222          * When queue is quiesced, we may be switching io scheduler, or
2223          * updating nr_hw_queues, or other things, and we can't run queue
2224          * any more, even __blk_mq_hctx_has_pending() can't be called safely.
2225          *
2226          * And queue will be rerun in blk_mq_unquiesce_queue() if it is
2227          * quiesced.
2228          */
2229         __blk_mq_run_dispatch_ops(hctx->queue, false,
2230                 need_run = !blk_queue_quiesced(hctx->queue) &&
2231                 blk_mq_hctx_has_pending(hctx));
2232
2233         if (need_run)
2234                 __blk_mq_delay_run_hw_queue(hctx, async, 0);
2235 }
2236 EXPORT_SYMBOL(blk_mq_run_hw_queue);
2237
2238 /*
2239  * Return prefered queue to dispatch from (if any) for non-mq aware IO
2240  * scheduler.
2241  */
2242 static struct blk_mq_hw_ctx *blk_mq_get_sq_hctx(struct request_queue *q)
2243 {
2244         struct blk_mq_ctx *ctx = blk_mq_get_ctx(q);
2245         /*
2246          * If the IO scheduler does not respect hardware queues when
2247          * dispatching, we just don't bother with multiple HW queues and
2248          * dispatch from hctx for the current CPU since running multiple queues
2249          * just causes lock contention inside the scheduler and pointless cache
2250          * bouncing.
2251          */
2252         struct blk_mq_hw_ctx *hctx = ctx->hctxs[HCTX_TYPE_DEFAULT];
2253
2254         if (!blk_mq_hctx_stopped(hctx))
2255                 return hctx;
2256         return NULL;
2257 }
2258
2259 /**
2260  * blk_mq_run_hw_queues - Run all hardware queues in a request queue.
2261  * @q: Pointer to the request queue to run.
2262  * @async: If we want to run the queue asynchronously.
2263  */
2264 void blk_mq_run_hw_queues(struct request_queue *q, bool async)
2265 {
2266         struct blk_mq_hw_ctx *hctx, *sq_hctx;
2267         unsigned long i;
2268
2269         sq_hctx = NULL;
2270         if (blk_queue_sq_sched(q))
2271                 sq_hctx = blk_mq_get_sq_hctx(q);
2272         queue_for_each_hw_ctx(q, hctx, i) {
2273                 if (blk_mq_hctx_stopped(hctx))
2274                         continue;
2275                 /*
2276                  * Dispatch from this hctx either if there's no hctx preferred
2277                  * by IO scheduler or if it has requests that bypass the
2278                  * scheduler.
2279                  */
2280                 if (!sq_hctx || sq_hctx == hctx ||
2281                     !list_empty_careful(&hctx->dispatch))
2282                         blk_mq_run_hw_queue(hctx, async);
2283         }
2284 }
2285 EXPORT_SYMBOL(blk_mq_run_hw_queues);
2286
2287 /**
2288  * blk_mq_delay_run_hw_queues - Run all hardware queues asynchronously.
2289  * @q: Pointer to the request queue to run.
2290  * @msecs: Milliseconds of delay to wait before running the queues.
2291  */
2292 void blk_mq_delay_run_hw_queues(struct request_queue *q, unsigned long msecs)
2293 {
2294         struct blk_mq_hw_ctx *hctx, *sq_hctx;
2295         unsigned long i;
2296
2297         sq_hctx = NULL;
2298         if (blk_queue_sq_sched(q))
2299                 sq_hctx = blk_mq_get_sq_hctx(q);
2300         queue_for_each_hw_ctx(q, hctx, i) {
2301                 if (blk_mq_hctx_stopped(hctx))
2302                         continue;
2303                 /*
2304                  * If there is already a run_work pending, leave the
2305                  * pending delay untouched. Otherwise, a hctx can stall
2306                  * if another hctx is re-delaying the other's work
2307                  * before the work executes.
2308                  */
2309                 if (delayed_work_pending(&hctx->run_work))
2310                         continue;
2311                 /*
2312                  * Dispatch from this hctx either if there's no hctx preferred
2313                  * by IO scheduler or if it has requests that bypass the
2314                  * scheduler.
2315                  */
2316                 if (!sq_hctx || sq_hctx == hctx ||
2317                     !list_empty_careful(&hctx->dispatch))
2318                         blk_mq_delay_run_hw_queue(hctx, msecs);
2319         }
2320 }
2321 EXPORT_SYMBOL(blk_mq_delay_run_hw_queues);
2322
2323 /*
2324  * This function is often used for pausing .queue_rq() by driver when
2325  * there isn't enough resource or some conditions aren't satisfied, and
2326  * BLK_STS_RESOURCE is usually returned.
2327  *
2328  * We do not guarantee that dispatch can be drained or blocked
2329  * after blk_mq_stop_hw_queue() returns. Please use
2330  * blk_mq_quiesce_queue() for that requirement.
2331  */
2332 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
2333 {
2334         cancel_delayed_work(&hctx->run_work);
2335
2336         set_bit(BLK_MQ_S_STOPPED, &hctx->state);
2337 }
2338 EXPORT_SYMBOL(blk_mq_stop_hw_queue);
2339
2340 /*
2341  * This function is often used for pausing .queue_rq() by driver when
2342  * there isn't enough resource or some conditions aren't satisfied, and
2343  * BLK_STS_RESOURCE is usually returned.
2344  *
2345  * We do not guarantee that dispatch can be drained or blocked
2346  * after blk_mq_stop_hw_queues() returns. Please use
2347  * blk_mq_quiesce_queue() for that requirement.
2348  */
2349 void blk_mq_stop_hw_queues(struct request_queue *q)
2350 {
2351         struct blk_mq_hw_ctx *hctx;
2352         unsigned long i;
2353
2354         queue_for_each_hw_ctx(q, hctx, i)
2355                 blk_mq_stop_hw_queue(hctx);
2356 }
2357 EXPORT_SYMBOL(blk_mq_stop_hw_queues);
2358
2359 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
2360 {
2361         clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
2362
2363         blk_mq_run_hw_queue(hctx, false);
2364 }
2365 EXPORT_SYMBOL(blk_mq_start_hw_queue);
2366
2367 void blk_mq_start_hw_queues(struct request_queue *q)
2368 {
2369         struct blk_mq_hw_ctx *hctx;
2370         unsigned long i;
2371
2372         queue_for_each_hw_ctx(q, hctx, i)
2373                 blk_mq_start_hw_queue(hctx);
2374 }
2375 EXPORT_SYMBOL(blk_mq_start_hw_queues);
2376
2377 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
2378 {
2379         if (!blk_mq_hctx_stopped(hctx))
2380                 return;
2381
2382         clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
2383         blk_mq_run_hw_queue(hctx, async);
2384 }
2385 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue);
2386
2387 void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async)
2388 {
2389         struct blk_mq_hw_ctx *hctx;
2390         unsigned long i;
2391
2392         queue_for_each_hw_ctx(q, hctx, i)
2393                 blk_mq_start_stopped_hw_queue(hctx, async);
2394 }
2395 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);
2396
2397 static void blk_mq_run_work_fn(struct work_struct *work)
2398 {
2399         struct blk_mq_hw_ctx *hctx;
2400
2401         hctx = container_of(work, struct blk_mq_hw_ctx, run_work.work);
2402
2403         /*
2404          * If we are stopped, don't run the queue.
2405          */
2406         if (blk_mq_hctx_stopped(hctx))
2407                 return;
2408
2409         __blk_mq_run_hw_queue(hctx);
2410 }
2411
2412 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx,
2413                                             struct request *rq,
2414                                             bool at_head)
2415 {
2416         struct blk_mq_ctx *ctx = rq->mq_ctx;
2417         enum hctx_type type = hctx->type;
2418
2419         lockdep_assert_held(&ctx->lock);
2420
2421         trace_block_rq_insert(rq);
2422
2423         if (at_head)
2424                 list_add(&rq->queuelist, &ctx->rq_lists[type]);
2425         else
2426                 list_add_tail(&rq->queuelist, &ctx->rq_lists[type]);
2427 }
2428
2429 void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
2430                              bool at_head)
2431 {
2432         struct blk_mq_ctx *ctx = rq->mq_ctx;
2433
2434         lockdep_assert_held(&ctx->lock);
2435
2436         __blk_mq_insert_req_list(hctx, rq, at_head);
2437         blk_mq_hctx_mark_pending(hctx, ctx);
2438 }
2439
2440 /**
2441  * blk_mq_request_bypass_insert - Insert a request at dispatch list.
2442  * @rq: Pointer to request to be inserted.
2443  * @at_head: true if the request should be inserted at the head of the list.
2444  * @run_queue: If we should run the hardware queue after inserting the request.
2445  *
2446  * Should only be used carefully, when the caller knows we want to
2447  * bypass a potential IO scheduler on the target device.
2448  */
2449 void blk_mq_request_bypass_insert(struct request *rq, bool at_head,
2450                                   bool run_queue)
2451 {
2452         struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
2453
2454         spin_lock(&hctx->lock);
2455         if (at_head)
2456                 list_add(&rq->queuelist, &hctx->dispatch);
2457         else
2458                 list_add_tail(&rq->queuelist, &hctx->dispatch);
2459         spin_unlock(&hctx->lock);
2460
2461         if (run_queue)
2462                 blk_mq_run_hw_queue(hctx, false);
2463 }
2464
2465 void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
2466                             struct list_head *list)
2467
2468 {
2469         struct request *rq;
2470         enum hctx_type type = hctx->type;
2471
2472         /*
2473          * preemption doesn't flush plug list, so it's possible ctx->cpu is
2474          * offline now
2475          */
2476         list_for_each_entry(rq, list, queuelist) {
2477                 BUG_ON(rq->mq_ctx != ctx);
2478                 trace_block_rq_insert(rq);
2479         }
2480
2481         spin_lock(&ctx->lock);
2482         list_splice_tail_init(list, &ctx->rq_lists[type]);
2483         blk_mq_hctx_mark_pending(hctx, ctx);
2484         spin_unlock(&ctx->lock);
2485 }
2486
2487 static void blk_mq_commit_rqs(struct blk_mq_hw_ctx *hctx, int *queued,
2488                               bool from_schedule)
2489 {
2490         if (hctx->queue->mq_ops->commit_rqs) {
2491                 trace_block_unplug(hctx->queue, *queued, !from_schedule);
2492                 hctx->queue->mq_ops->commit_rqs(hctx);
2493         }
2494         *queued = 0;
2495 }
2496
2497 static void blk_mq_bio_to_request(struct request *rq, struct bio *bio,
2498                 unsigned int nr_segs)
2499 {
2500         int err;
2501
2502         if (bio->bi_opf & REQ_RAHEAD)
2503                 rq->cmd_flags |= REQ_FAILFAST_MASK;
2504
2505         rq->__sector = bio->bi_iter.bi_sector;
2506         blk_rq_bio_prep(rq, bio, nr_segs);
2507
2508         /* This can't fail, since GFP_NOIO includes __GFP_DIRECT_RECLAIM. */
2509         err = blk_crypto_rq_bio_prep(rq, bio, GFP_NOIO);
2510         WARN_ON_ONCE(err);
2511
2512         blk_account_io_start(rq);
2513 }
2514
2515 static blk_status_t __blk_mq_issue_directly(struct blk_mq_hw_ctx *hctx,
2516                                             struct request *rq, bool last)
2517 {
2518         struct request_queue *q = rq->q;
2519         struct blk_mq_queue_data bd = {
2520                 .rq = rq,
2521                 .last = last,
2522         };
2523         blk_status_t ret;
2524
2525         /*
2526          * For OK queue, we are done. For error, caller may kill it.
2527          * Any other error (busy), just add it to our list as we
2528          * previously would have done.
2529          */
2530         ret = q->mq_ops->queue_rq(hctx, &bd);
2531         switch (ret) {
2532         case BLK_STS_OK:
2533                 blk_mq_update_dispatch_busy(hctx, false);
2534                 break;
2535         case BLK_STS_RESOURCE:
2536         case BLK_STS_DEV_RESOURCE:
2537                 blk_mq_update_dispatch_busy(hctx, true);
2538                 __blk_mq_requeue_request(rq);
2539                 break;
2540         default:
2541                 blk_mq_update_dispatch_busy(hctx, false);
2542                 break;
2543         }
2544
2545         return ret;
2546 }
2547
2548 static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
2549                                                 struct request *rq,
2550                                                 bool bypass_insert, bool last)
2551 {
2552         struct request_queue *q = rq->q;
2553         bool run_queue = true;
2554         int budget_token;
2555
2556         /*
2557          * RCU or SRCU read lock is needed before checking quiesced flag.
2558          *
2559          * When queue is stopped or quiesced, ignore 'bypass_insert' from
2560          * blk_mq_request_issue_directly(), and return BLK_STS_OK to caller,
2561          * and avoid driver to try to dispatch again.
2562          */
2563         if (blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q)) {
2564                 run_queue = false;
2565                 bypass_insert = false;
2566                 goto insert;
2567         }
2568
2569         if ((rq->rq_flags & RQF_ELV) && !bypass_insert)
2570                 goto insert;
2571
2572         budget_token = blk_mq_get_dispatch_budget(q);
2573         if (budget_token < 0)
2574                 goto insert;
2575
2576         blk_mq_set_rq_budget_token(rq, budget_token);
2577
2578         if (!blk_mq_get_driver_tag(rq)) {
2579                 blk_mq_put_dispatch_budget(q, budget_token);
2580                 goto insert;
2581         }
2582
2583         return __blk_mq_issue_directly(hctx, rq, last);
2584 insert:
2585         if (bypass_insert)
2586                 return BLK_STS_RESOURCE;
2587
2588         blk_mq_sched_insert_request(rq, false, run_queue, false);
2589
2590         return BLK_STS_OK;
2591 }
2592
2593 /**
2594  * blk_mq_try_issue_directly - Try to send a request directly to device driver.
2595  * @hctx: Pointer of the associated hardware queue.
2596  * @rq: Pointer to request to be sent.
2597  *
2598  * If the device has enough resources to accept a new request now, send the
2599  * request directly to device driver. Else, insert at hctx->dispatch queue, so
2600  * we can try send it another time in the future. Requests inserted at this
2601  * queue have higher priority.
2602  */
2603 static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
2604                 struct request *rq)
2605 {
2606         blk_status_t ret =
2607                 __blk_mq_try_issue_directly(hctx, rq, false, true);
2608
2609         if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE)
2610                 blk_mq_request_bypass_insert(rq, false, true);
2611         else if (ret != BLK_STS_OK)
2612                 blk_mq_end_request(rq, ret);
2613 }
2614
2615 static blk_status_t blk_mq_request_issue_directly(struct request *rq, bool last)
2616 {
2617         return __blk_mq_try_issue_directly(rq->mq_hctx, rq, true, last);
2618 }
2619
2620 static void blk_mq_plug_issue_direct(struct blk_plug *plug, bool from_schedule)
2621 {
2622         struct blk_mq_hw_ctx *hctx = NULL;
2623         struct request *rq;
2624         int queued = 0;
2625         int errors = 0;
2626
2627         while ((rq = rq_list_pop(&plug->mq_list))) {
2628                 bool last = rq_list_empty(plug->mq_list);
2629                 blk_status_t ret;
2630
2631                 if (hctx != rq->mq_hctx) {
2632                         if (hctx)
2633                                 blk_mq_commit_rqs(hctx, &queued, from_schedule);
2634                         hctx = rq->mq_hctx;
2635                 }
2636
2637                 ret = blk_mq_request_issue_directly(rq, last);
2638                 switch (ret) {
2639                 case BLK_STS_OK:
2640                         queued++;
2641                         break;
2642                 case BLK_STS_RESOURCE:
2643                 case BLK_STS_DEV_RESOURCE:
2644                         blk_mq_request_bypass_insert(rq, false, true);
2645                         blk_mq_commit_rqs(hctx, &queued, from_schedule);
2646                         return;
2647                 default:
2648                         blk_mq_end_request(rq, ret);
2649                         errors++;
2650                         break;
2651                 }
2652         }
2653
2654         /*
2655          * If we didn't flush the entire list, we could have told the driver
2656          * there was more coming, but that turned out to be a lie.
2657          */
2658         if (errors)
2659                 blk_mq_commit_rqs(hctx, &queued, from_schedule);
2660 }
2661
2662 static void __blk_mq_flush_plug_list(struct request_queue *q,
2663                                      struct blk_plug *plug)
2664 {
2665         if (blk_queue_quiesced(q))
2666                 return;
2667         q->mq_ops->queue_rqs(&plug->mq_list);
2668 }
2669
2670 static void blk_mq_dispatch_plug_list(struct blk_plug *plug, bool from_sched)
2671 {
2672         struct blk_mq_hw_ctx *this_hctx = NULL;
2673         struct blk_mq_ctx *this_ctx = NULL;
2674         struct request *requeue_list = NULL;
2675         unsigned int depth = 0;
2676         LIST_HEAD(list);
2677
2678         do {
2679                 struct request *rq = rq_list_pop(&plug->mq_list);
2680
2681                 if (!this_hctx) {
2682                         this_hctx = rq->mq_hctx;
2683                         this_ctx = rq->mq_ctx;
2684                 } else if (this_hctx != rq->mq_hctx || this_ctx != rq->mq_ctx) {
2685                         rq_list_add(&requeue_list, rq);
2686                         continue;
2687                 }
2688                 list_add_tail(&rq->queuelist, &list);
2689                 depth++;
2690         } while (!rq_list_empty(plug->mq_list));
2691
2692         plug->mq_list = requeue_list;
2693         trace_block_unplug(this_hctx->queue, depth, !from_sched);
2694         blk_mq_sched_insert_requests(this_hctx, this_ctx, &list, from_sched);
2695 }
2696
2697 void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
2698 {
2699         struct request *rq;
2700
2701         if (rq_list_empty(plug->mq_list))
2702                 return;
2703         plug->rq_count = 0;
2704
2705         if (!plug->multiple_queues && !plug->has_elevator && !from_schedule) {
2706                 struct request_queue *q;
2707
2708                 rq = rq_list_peek(&plug->mq_list);
2709                 q = rq->q;
2710
2711                 /*
2712                  * Peek first request and see if we have a ->queue_rqs() hook.
2713                  * If we do, we can dispatch the whole plug list in one go. We
2714                  * already know at this point that all requests belong to the
2715                  * same queue, caller must ensure that's the case.
2716                  *
2717                  * Since we pass off the full list to the driver at this point,
2718                  * we do not increment the active request count for the queue.
2719                  * Bypass shared tags for now because of that.
2720                  */
2721                 if (q->mq_ops->queue_rqs &&
2722                     !(rq->mq_hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED)) {
2723                         blk_mq_run_dispatch_ops(q,
2724                                 __blk_mq_flush_plug_list(q, plug));
2725                         if (rq_list_empty(plug->mq_list))
2726                                 return;
2727                 }
2728
2729                 blk_mq_run_dispatch_ops(q,
2730                                 blk_mq_plug_issue_direct(plug, false));
2731                 if (rq_list_empty(plug->mq_list))
2732                         return;
2733         }
2734
2735         do {
2736                 blk_mq_dispatch_plug_list(plug, from_schedule);
2737         } while (!rq_list_empty(plug->mq_list));
2738 }
2739
2740 void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx,
2741                 struct list_head *list)
2742 {
2743         int queued = 0;
2744         int errors = 0;
2745
2746         while (!list_empty(list)) {
2747                 blk_status_t ret;
2748                 struct request *rq = list_first_entry(list, struct request,
2749                                 queuelist);
2750
2751                 list_del_init(&rq->queuelist);
2752                 ret = blk_mq_request_issue_directly(rq, list_empty(list));
2753                 if (ret != BLK_STS_OK) {
2754                         errors++;
2755                         if (ret == BLK_STS_RESOURCE ||
2756                                         ret == BLK_STS_DEV_RESOURCE) {
2757                                 blk_mq_request_bypass_insert(rq, false,
2758                                                         list_empty(list));
2759                                 break;
2760                         }
2761                         blk_mq_end_request(rq, ret);
2762                 } else
2763                         queued++;
2764         }
2765
2766         /*
2767          * If we didn't flush the entire list, we could have told
2768          * the driver there was more coming, but that turned out to
2769          * be a lie.
2770          */
2771         if ((!list_empty(list) || errors) &&
2772              hctx->queue->mq_ops->commit_rqs && queued)
2773                 hctx->queue->mq_ops->commit_rqs(hctx);
2774 }
2775
2776 static bool blk_mq_attempt_bio_merge(struct request_queue *q,
2777                                      struct bio *bio, unsigned int nr_segs)
2778 {
2779         if (!blk_queue_nomerges(q) && bio_mergeable(bio)) {
2780                 if (blk_attempt_plug_merge(q, bio, nr_segs))
2781                         return true;
2782                 if (blk_mq_sched_bio_merge(q, bio, nr_segs))
2783                         return true;
2784         }
2785         return false;
2786 }
2787
2788 static struct request *blk_mq_get_new_requests(struct request_queue *q,
2789                                                struct blk_plug *plug,
2790                                                struct bio *bio,
2791                                                unsigned int nsegs)
2792 {
2793         struct blk_mq_alloc_data data = {
2794                 .q              = q,
2795                 .nr_tags        = 1,
2796                 .cmd_flags      = bio->bi_opf,
2797         };
2798         struct request *rq;
2799
2800         if (unlikely(bio_queue_enter(bio)))
2801                 return NULL;
2802
2803         if (blk_mq_attempt_bio_merge(q, bio, nsegs))
2804                 goto queue_exit;
2805
2806         rq_qos_throttle(q, bio);
2807
2808         if (plug) {
2809                 data.nr_tags = plug->nr_ios;
2810                 plug->nr_ios = 1;
2811                 data.cached_rq = &plug->cached_rq;
2812         }
2813
2814         rq = __blk_mq_alloc_requests(&data);
2815         if (rq)
2816                 return rq;
2817         rq_qos_cleanup(q, bio);
2818         if (bio->bi_opf & REQ_NOWAIT)
2819                 bio_wouldblock_error(bio);
2820 queue_exit:
2821         blk_queue_exit(q);
2822         return NULL;
2823 }
2824
2825 static inline struct request *blk_mq_get_cached_request(struct request_queue *q,
2826                 struct blk_plug *plug, struct bio **bio, unsigned int nsegs)
2827 {
2828         struct request *rq;
2829
2830         if (!plug)
2831                 return NULL;
2832         rq = rq_list_peek(&plug->cached_rq);
2833         if (!rq || rq->q != q)
2834                 return NULL;
2835
2836         if (blk_mq_attempt_bio_merge(q, *bio, nsegs)) {
2837                 *bio = NULL;
2838                 return NULL;
2839         }
2840
2841         if (blk_mq_get_hctx_type((*bio)->bi_opf) != rq->mq_hctx->type)
2842                 return NULL;
2843         if (op_is_flush(rq->cmd_flags) != op_is_flush((*bio)->bi_opf))
2844                 return NULL;
2845
2846         /*
2847          * If any qos ->throttle() end up blocking, we will have flushed the
2848          * plug and hence killed the cached_rq list as well. Pop this entry
2849          * before we throttle.
2850          */
2851         plug->cached_rq = rq_list_next(rq);
2852         rq_qos_throttle(q, *bio);
2853
2854         rq->cmd_flags = (*bio)->bi_opf;
2855         INIT_LIST_HEAD(&rq->queuelist);
2856         return rq;
2857 }
2858
2859 static void bio_set_ioprio(struct bio *bio)
2860 {
2861         /* Nobody set ioprio so far? Initialize it based on task's nice value */
2862         if (IOPRIO_PRIO_CLASS(bio->bi_ioprio) == IOPRIO_CLASS_NONE)
2863                 bio->bi_ioprio = get_current_ioprio();
2864         blkcg_set_ioprio(bio);
2865 }
2866
2867 /**
2868  * blk_mq_submit_bio - Create and send a request to block device.
2869  * @bio: Bio pointer.
2870  *
2871  * Builds up a request structure from @q and @bio and send to the device. The
2872  * request may not be queued directly to hardware if:
2873  * * This request can be merged with another one
2874  * * We want to place request at plug queue for possible future merging
2875  * * There is an IO scheduler active at this queue
2876  *
2877  * It will not queue the request if there is an error with the bio, or at the
2878  * request creation.
2879  */
2880 void blk_mq_submit_bio(struct bio *bio)
2881 {
2882         struct request_queue *q = bdev_get_queue(bio->bi_bdev);
2883         struct blk_plug *plug = blk_mq_plug(bio);
2884         const int is_sync = op_is_sync(bio->bi_opf);
2885         struct request *rq;
2886         unsigned int nr_segs = 1;
2887         blk_status_t ret;
2888
2889         bio = blk_queue_bounce(bio, q);
2890         if (bio_may_exceed_limits(bio, &q->limits))
2891                 bio = __bio_split_to_limits(bio, &q->limits, &nr_segs);
2892
2893         if (!bio_integrity_prep(bio))
2894                 return;
2895
2896         bio_set_ioprio(bio);
2897
2898         rq = blk_mq_get_cached_request(q, plug, &bio, nr_segs);
2899         if (!rq) {
2900                 if (!bio)
2901                         return;
2902                 rq = blk_mq_get_new_requests(q, plug, bio, nr_segs);
2903                 if (unlikely(!rq))
2904                         return;
2905         }
2906
2907         trace_block_getrq(bio);
2908
2909         rq_qos_track(q, rq, bio);
2910
2911         blk_mq_bio_to_request(rq, bio, nr_segs);
2912
2913         ret = blk_crypto_init_request(rq);
2914         if (ret != BLK_STS_OK) {
2915                 bio->bi_status = ret;
2916                 bio_endio(bio);
2917                 blk_mq_free_request(rq);
2918                 return;
2919         }
2920
2921         if (op_is_flush(bio->bi_opf)) {
2922                 blk_insert_flush(rq);
2923                 return;
2924         }
2925
2926         if (plug)
2927                 blk_add_rq_to_plug(plug, rq);
2928         else if ((rq->rq_flags & RQF_ELV) ||
2929                  (rq->mq_hctx->dispatch_busy &&
2930                   (q->nr_hw_queues == 1 || !is_sync)))
2931                 blk_mq_sched_insert_request(rq, false, true, true);
2932         else
2933                 blk_mq_run_dispatch_ops(rq->q,
2934                                 blk_mq_try_issue_directly(rq->mq_hctx, rq));
2935 }
2936
2937 #ifdef CONFIG_BLK_MQ_STACKING
2938 /**
2939  * blk_insert_cloned_request - Helper for stacking drivers to submit a request
2940  * @rq: the request being queued
2941  */
2942 blk_status_t blk_insert_cloned_request(struct request *rq)
2943 {
2944         struct request_queue *q = rq->q;
2945         unsigned int max_sectors = blk_queue_get_max_sectors(q, req_op(rq));
2946         blk_status_t ret;
2947
2948         if (blk_rq_sectors(rq) > max_sectors) {
2949                 /*
2950                  * SCSI device does not have a good way to return if
2951                  * Write Same/Zero is actually supported. If a device rejects
2952                  * a non-read/write command (discard, write same,etc.) the
2953                  * low-level device driver will set the relevant queue limit to
2954                  * 0 to prevent blk-lib from issuing more of the offending
2955                  * operations. Commands queued prior to the queue limit being
2956                  * reset need to be completed with BLK_STS_NOTSUPP to avoid I/O
2957                  * errors being propagated to upper layers.
2958                  */
2959                 if (max_sectors == 0)
2960                         return BLK_STS_NOTSUPP;
2961
2962                 printk(KERN_ERR "%s: over max size limit. (%u > %u)\n",
2963                         __func__, blk_rq_sectors(rq), max_sectors);
2964                 return BLK_STS_IOERR;
2965         }
2966
2967         /*
2968          * The queue settings related to segment counting may differ from the
2969          * original queue.
2970          */
2971         rq->nr_phys_segments = blk_recalc_rq_segments(rq);
2972         if (rq->nr_phys_segments > queue_max_segments(q)) {
2973                 printk(KERN_ERR "%s: over max segments limit. (%hu > %hu)\n",
2974                         __func__, rq->nr_phys_segments, queue_max_segments(q));
2975                 return BLK_STS_IOERR;
2976         }
2977
2978         if (q->disk && should_fail_request(q->disk->part0, blk_rq_bytes(rq)))
2979                 return BLK_STS_IOERR;
2980
2981         if (blk_crypto_insert_cloned_request(rq))
2982                 return BLK_STS_IOERR;
2983
2984         blk_account_io_start(rq);
2985
2986         /*
2987          * Since we have a scheduler attached on the top device,
2988          * bypass a potential scheduler on the bottom device for
2989          * insert.
2990          */
2991         blk_mq_run_dispatch_ops(q,
2992                         ret = blk_mq_request_issue_directly(rq, true));
2993         if (ret)
2994                 blk_account_io_done(rq, ktime_get_ns());
2995         return ret;
2996 }
2997 EXPORT_SYMBOL_GPL(blk_insert_cloned_request);
2998
2999 /**
3000  * blk_rq_unprep_clone - Helper function to free all bios in a cloned request
3001  * @rq: the clone request to be cleaned up
3002  *
3003  * Description:
3004  *     Free all bios in @rq for a cloned request.
3005  */
3006 void blk_rq_unprep_clone(struct request *rq)
3007 {
3008         struct bio *bio;
3009
3010         while ((bio = rq->bio) != NULL) {
3011                 rq->bio = bio->bi_next;
3012
3013                 bio_put(bio);
3014         }
3015 }
3016 EXPORT_SYMBOL_GPL(blk_rq_unprep_clone);
3017
3018 /**
3019  * blk_rq_prep_clone - Helper function to setup clone request
3020  * @rq: the request to be setup
3021  * @rq_src: original request to be cloned
3022  * @bs: bio_set that bios for clone are allocated from
3023  * @gfp_mask: memory allocation mask for bio
3024  * @bio_ctr: setup function to be called for each clone bio.
3025  *           Returns %0 for success, non %0 for failure.
3026  * @data: private data to be passed to @bio_ctr
3027  *
3028  * Description:
3029  *     Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq.
3030  *     Also, pages which the original bios are pointing to are not copied
3031  *     and the cloned bios just point same pages.
3032  *     So cloned bios must be completed before original bios, which means
3033  *     the caller must complete @rq before @rq_src.
3034  */
3035 int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
3036                       struct bio_set *bs, gfp_t gfp_mask,
3037                       int (*bio_ctr)(struct bio *, struct bio *, void *),
3038                       void *data)
3039 {
3040         struct bio *bio, *bio_src;
3041
3042         if (!bs)
3043                 bs = &fs_bio_set;
3044
3045         __rq_for_each_bio(bio_src, rq_src) {
3046                 bio = bio_alloc_clone(rq->q->disk->part0, bio_src, gfp_mask,
3047                                       bs);
3048                 if (!bio)
3049                         goto free_and_out;
3050
3051                 if (bio_ctr && bio_ctr(bio, bio_src, data))
3052                         goto free_and_out;
3053
3054                 if (rq->bio) {
3055                         rq->biotail->bi_next = bio;
3056                         rq->biotail = bio;
3057                 } else {
3058                         rq->bio = rq->biotail = bio;
3059                 }
3060                 bio = NULL;
3061         }
3062
3063         /* Copy attributes of the original request to the clone request. */
3064         rq->__sector = blk_rq_pos(rq_src);
3065         rq->__data_len = blk_rq_bytes(rq_src);
3066         if (rq_src->rq_flags & RQF_SPECIAL_PAYLOAD) {
3067                 rq->rq_flags |= RQF_SPECIAL_PAYLOAD;
3068                 rq->special_vec = rq_src->special_vec;
3069         }
3070         rq->nr_phys_segments = rq_src->nr_phys_segments;
3071         rq->ioprio = rq_src->ioprio;
3072
3073         if (rq->bio && blk_crypto_rq_bio_prep(rq, rq->bio, gfp_mask) < 0)
3074                 goto free_and_out;
3075
3076         return 0;
3077
3078 free_and_out:
3079         if (bio)
3080                 bio_put(bio);
3081         blk_rq_unprep_clone(rq);
3082
3083         return -ENOMEM;
3084 }
3085 EXPORT_SYMBOL_GPL(blk_rq_prep_clone);
3086 #endif /* CONFIG_BLK_MQ_STACKING */
3087
3088 /*
3089  * Steal bios from a request and add them to a bio list.
3090  * The request must not have been partially completed before.
3091  */
3092 void blk_steal_bios(struct bio_list *list, struct request *rq)
3093 {
3094         if (rq->bio) {
3095                 if (list->tail)
3096                         list->tail->bi_next = rq->bio;
3097                 else
3098                         list->head = rq->bio;
3099                 list->tail = rq->biotail;
3100
3101                 rq->bio = NULL;
3102                 rq->biotail = NULL;
3103         }
3104
3105         rq->__data_len = 0;
3106 }
3107 EXPORT_SYMBOL_GPL(blk_steal_bios);
3108
3109 static size_t order_to_size(unsigned int order)
3110 {
3111         return (size_t)PAGE_SIZE << order;
3112 }
3113
3114 /* called before freeing request pool in @tags */
3115 static void blk_mq_clear_rq_mapping(struct blk_mq_tags *drv_tags,
3116                                     struct blk_mq_tags *tags)
3117 {
3118         struct page *page;
3119         unsigned long flags;
3120
3121         /*
3122          * There is no need to clear mapping if driver tags is not initialized
3123          * or the mapping belongs to the driver tags.
3124          */
3125         if (!drv_tags || drv_tags == tags)
3126                 return;
3127
3128         list_for_each_entry(page, &tags->page_list, lru) {
3129                 unsigned long start = (unsigned long)page_address(page);
3130                 unsigned long end = start + order_to_size(page->private);
3131                 int i;
3132
3133                 for (i = 0; i < drv_tags->nr_tags; i++) {
3134                         struct request *rq = drv_tags->rqs[i];
3135                         unsigned long rq_addr = (unsigned long)rq;
3136
3137                         if (rq_addr >= start && rq_addr < end) {
3138                                 WARN_ON_ONCE(req_ref_read(rq) != 0);
3139                                 cmpxchg(&drv_tags->rqs[i], rq, NULL);
3140                         }
3141                 }
3142         }
3143
3144         /*
3145          * Wait until all pending iteration is done.
3146          *
3147          * Request reference is cleared and it is guaranteed to be observed
3148          * after the ->lock is released.
3149          */
3150         spin_lock_irqsave(&drv_tags->lock, flags);
3151         spin_unlock_irqrestore(&drv_tags->lock, flags);
3152 }
3153
3154 void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
3155                      unsigned int hctx_idx)
3156 {
3157         struct blk_mq_tags *drv_tags;
3158         struct page *page;
3159
3160         if (list_empty(&tags->page_list))
3161                 return;
3162
3163         if (blk_mq_is_shared_tags(set->flags))
3164                 drv_tags = set->shared_tags;
3165         else
3166                 drv_tags = set->tags[hctx_idx];
3167
3168         if (tags->static_rqs && set->ops->exit_request) {
3169                 int i;
3170
3171                 for (i = 0; i < tags->nr_tags; i++) {
3172                         struct request *rq = tags->static_rqs[i];
3173
3174                         if (!rq)
3175                                 continue;
3176                         set->ops->exit_request(set, rq, hctx_idx);
3177                         tags->static_rqs[i] = NULL;
3178                 }
3179         }
3180
3181         blk_mq_clear_rq_mapping(drv_tags, tags);
3182
3183         while (!list_empty(&tags->page_list)) {
3184                 page = list_first_entry(&tags->page_list, struct page, lru);
3185                 list_del_init(&page->lru);
3186                 /*
3187                  * Remove kmemleak object previously allocated in
3188                  * blk_mq_alloc_rqs().
3189                  */
3190                 kmemleak_free(page_address(page));
3191                 __free_pages(page, page->private);
3192         }
3193 }
3194
3195 void blk_mq_free_rq_map(struct blk_mq_tags *tags)
3196 {
3197         kfree(tags->rqs);
3198         tags->rqs = NULL;
3199         kfree(tags->static_rqs);
3200         tags->static_rqs = NULL;
3201
3202         blk_mq_free_tags(tags);
3203 }
3204
3205 static enum hctx_type hctx_idx_to_type(struct blk_mq_tag_set *set,
3206                 unsigned int hctx_idx)
3207 {
3208         int i;
3209
3210         for (i = 0; i < set->nr_maps; i++) {
3211                 unsigned int start = set->map[i].queue_offset;
3212                 unsigned int end = start + set->map[i].nr_queues;
3213
3214                 if (hctx_idx >= start && hctx_idx < end)
3215                         break;
3216         }
3217
3218         if (i >= set->nr_maps)
3219                 i = HCTX_TYPE_DEFAULT;
3220
3221         return i;
3222 }
3223
3224 static int blk_mq_get_hctx_node(struct blk_mq_tag_set *set,
3225                 unsigned int hctx_idx)
3226 {
3227         enum hctx_type type = hctx_idx_to_type(set, hctx_idx);
3228
3229         return blk_mq_hw_queue_to_node(&set->map[type], hctx_idx);
3230 }
3231
3232 static struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set,
3233                                                unsigned int hctx_idx,
3234                                                unsigned int nr_tags,
3235                                                unsigned int reserved_tags)
3236 {
3237         int node = blk_mq_get_hctx_node(set, hctx_idx);
3238         struct blk_mq_tags *tags;
3239
3240         if (node == NUMA_NO_NODE)
3241                 node = set->numa_node;
3242
3243         tags = blk_mq_init_tags(nr_tags, reserved_tags, node,
3244                                 BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags));
3245         if (!tags)
3246                 return NULL;
3247
3248         tags->rqs = kcalloc_node(nr_tags, sizeof(struct request *),
3249                                  GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
3250                                  node);
3251         if (!tags->rqs) {
3252                 blk_mq_free_tags(tags);
3253                 return NULL;
3254         }
3255
3256         tags->static_rqs = kcalloc_node(nr_tags, sizeof(struct request *),
3257                                         GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
3258                                         node);
3259         if (!tags->static_rqs) {
3260                 kfree(tags->rqs);
3261                 blk_mq_free_tags(tags);
3262                 return NULL;
3263         }
3264
3265         return tags;
3266 }
3267
3268 static int blk_mq_init_request(struct blk_mq_tag_set *set, struct request *rq,
3269                                unsigned int hctx_idx, int node)
3270 {
3271         int ret;
3272
3273         if (set->ops->init_request) {
3274                 ret = set->ops->init_request(set, rq, hctx_idx, node);
3275                 if (ret)
3276                         return ret;
3277         }
3278
3279         WRITE_ONCE(rq->state, MQ_RQ_IDLE);
3280         return 0;
3281 }
3282
3283 static int blk_mq_alloc_rqs(struct blk_mq_tag_set *set,
3284                             struct blk_mq_tags *tags,
3285                             unsigned int hctx_idx, unsigned int depth)
3286 {
3287         unsigned int i, j, entries_per_page, max_order = 4;
3288         int node = blk_mq_get_hctx_node(set, hctx_idx);
3289         size_t rq_size, left;
3290
3291         if (node == NUMA_NO_NODE)
3292                 node = set->numa_node;
3293
3294         INIT_LIST_HEAD(&tags->page_list);
3295
3296         /*
3297          * rq_size is the size of the request plus driver payload, rounded
3298          * to the cacheline size
3299          */
3300         rq_size = round_up(sizeof(struct request) + set->cmd_size,
3301                                 cache_line_size());
3302         left = rq_size * depth;
3303
3304         for (i = 0; i < depth; ) {
3305                 int this_order = max_order;
3306                 struct page *page;
3307                 int to_do;
3308                 void *p;
3309
3310                 while (this_order && left < order_to_size(this_order - 1))
3311                         this_order--;
3312
3313                 do {
3314                         page = alloc_pages_node(node,
3315                                 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY | __GFP_ZERO,
3316                                 this_order);
3317                         if (page)
3318                                 break;
3319                         if (!this_order--)
3320                                 break;
3321                         if (order_to_size(this_order) < rq_size)
3322                                 break;
3323                 } while (1);
3324
3325                 if (!page)
3326                         goto fail;
3327
3328                 page->private = this_order;
3329                 list_add_tail(&page->lru, &tags->page_list);
3330
3331                 p = page_address(page);
3332                 /*
3333                  * Allow kmemleak to scan these pages as they contain pointers
3334                  * to additional allocations like via ops->init_request().
3335                  */
3336                 kmemleak_alloc(p, order_to_size(this_order), 1, GFP_NOIO);
3337                 entries_per_page = order_to_size(this_order) / rq_size;
3338                 to_do = min(entries_per_page, depth - i);
3339                 left -= to_do * rq_size;
3340                 for (j = 0; j < to_do; j++) {
3341                         struct request *rq = p;
3342
3343                         tags->static_rqs[i] = rq;
3344                         if (blk_mq_init_request(set, rq, hctx_idx, node)) {
3345                                 tags->static_rqs[i] = NULL;
3346                                 goto fail;
3347                         }
3348
3349                         p += rq_size;
3350                         i++;
3351                 }
3352         }
3353         return 0;
3354
3355 fail:
3356         blk_mq_free_rqs(set, tags, hctx_idx);
3357         return -ENOMEM;
3358 }
3359
3360 struct rq_iter_data {
3361         struct blk_mq_hw_ctx *hctx;
3362         bool has_rq;
3363 };
3364
3365 static bool blk_mq_has_request(struct request *rq, void *data)
3366 {
3367         struct rq_iter_data *iter_data = data;
3368
3369         if (rq->mq_hctx != iter_data->hctx)
3370                 return true;
3371         iter_data->has_rq = true;
3372         return false;
3373 }
3374
3375 static bool blk_mq_hctx_has_requests(struct blk_mq_hw_ctx *hctx)
3376 {
3377         struct blk_mq_tags *tags = hctx->sched_tags ?
3378                         hctx->sched_tags : hctx->tags;
3379         struct rq_iter_data data = {
3380                 .hctx   = hctx,
3381         };
3382
3383         blk_mq_all_tag_iter(tags, blk_mq_has_request, &data);
3384         return data.has_rq;
3385 }
3386
3387 static inline bool blk_mq_last_cpu_in_hctx(unsigned int cpu,
3388                 struct blk_mq_hw_ctx *hctx)
3389 {
3390         if (cpumask_first_and(hctx->cpumask, cpu_online_mask) != cpu)
3391                 return false;
3392         if (cpumask_next_and(cpu, hctx->cpumask, cpu_online_mask) < nr_cpu_ids)
3393                 return false;
3394         return true;
3395 }
3396
3397 static int blk_mq_hctx_notify_offline(unsigned int cpu, struct hlist_node *node)
3398 {
3399         struct blk_mq_hw_ctx *hctx = hlist_entry_safe(node,
3400                         struct blk_mq_hw_ctx, cpuhp_online);
3401
3402         if (!cpumask_test_cpu(cpu, hctx->cpumask) ||
3403             !blk_mq_last_cpu_in_hctx(cpu, hctx))
3404                 return 0;
3405
3406         /*
3407          * Prevent new request from being allocated on the current hctx.
3408          *
3409          * The smp_mb__after_atomic() Pairs with the implied barrier in
3410          * test_and_set_bit_lock in sbitmap_get().  Ensures the inactive flag is
3411          * seen once we return from the tag allocator.
3412          */
3413         set_bit(BLK_MQ_S_INACTIVE, &hctx->state);
3414         smp_mb__after_atomic();
3415
3416         /*
3417          * Try to grab a reference to the queue and wait for any outstanding
3418          * requests.  If we could not grab a reference the queue has been
3419          * frozen and there are no requests.
3420          */
3421         if (percpu_ref_tryget(&hctx->queue->q_usage_counter)) {
3422                 while (blk_mq_hctx_has_requests(hctx))
3423                         msleep(5);
3424                 percpu_ref_put(&hctx->queue->q_usage_counter);
3425         }
3426
3427         return 0;
3428 }
3429
3430 static int blk_mq_hctx_notify_online(unsigned int cpu, struct hlist_node *node)
3431 {
3432         struct blk_mq_hw_ctx *hctx = hlist_entry_safe(node,
3433                         struct blk_mq_hw_ctx, cpuhp_online);
3434
3435         if (cpumask_test_cpu(cpu, hctx->cpumask))
3436                 clear_bit(BLK_MQ_S_INACTIVE, &hctx->state);
3437         return 0;
3438 }
3439
3440 /*
3441  * 'cpu' is going away. splice any existing rq_list entries from this
3442  * software queue to the hw queue dispatch list, and ensure that it
3443  * gets run.
3444  */
3445 static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node)
3446 {
3447         struct blk_mq_hw_ctx *hctx;
3448         struct blk_mq_ctx *ctx;
3449         LIST_HEAD(tmp);
3450         enum hctx_type type;
3451
3452         hctx = hlist_entry_safe(node, struct blk_mq_hw_ctx, cpuhp_dead);
3453         if (!cpumask_test_cpu(cpu, hctx->cpumask))
3454                 return 0;
3455
3456         ctx = __blk_mq_get_ctx(hctx->queue, cpu);
3457         type = hctx->type;
3458
3459         spin_lock(&ctx->lock);
3460         if (!list_empty(&ctx->rq_lists[type])) {
3461                 list_splice_init(&ctx->rq_lists[type], &tmp);
3462                 blk_mq_hctx_clear_pending(hctx, ctx);
3463         }
3464         spin_unlock(&ctx->lock);
3465
3466         if (list_empty(&tmp))
3467                 return 0;
3468
3469         spin_lock(&hctx->lock);
3470         list_splice_tail_init(&tmp, &hctx->dispatch);
3471         spin_unlock(&hctx->lock);
3472
3473         blk_mq_run_hw_queue(hctx, true);
3474         return 0;
3475 }
3476
3477 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx *hctx)
3478 {
3479         if (!(hctx->flags & BLK_MQ_F_STACKING))
3480                 cpuhp_state_remove_instance_nocalls(CPUHP_AP_BLK_MQ_ONLINE,
3481                                                     &hctx->cpuhp_online);
3482         cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD,
3483                                             &hctx->cpuhp_dead);
3484 }
3485
3486 /*
3487  * Before freeing hw queue, clearing the flush request reference in
3488  * tags->rqs[] for avoiding potential UAF.
3489  */
3490 static void blk_mq_clear_flush_rq_mapping(struct blk_mq_tags *tags,
3491                 unsigned int queue_depth, struct request *flush_rq)
3492 {
3493         int i;
3494         unsigned long flags;
3495
3496         /* The hw queue may not be mapped yet */
3497         if (!tags)
3498                 return;
3499
3500         WARN_ON_ONCE(req_ref_read(flush_rq) != 0);
3501
3502         for (i = 0; i < queue_depth; i++)
3503                 cmpxchg(&tags->rqs[i], flush_rq, NULL);
3504
3505         /*
3506          * Wait until all pending iteration is done.
3507          *
3508          * Request reference is cleared and it is guaranteed to be observed
3509          * after the ->lock is released.
3510          */
3511         spin_lock_irqsave(&tags->lock, flags);
3512         spin_unlock_irqrestore(&tags->lock, flags);
3513 }
3514
3515 /* hctx->ctxs will be freed in queue's release handler */
3516 static void blk_mq_exit_hctx(struct request_queue *q,
3517                 struct blk_mq_tag_set *set,
3518                 struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
3519 {
3520         struct request *flush_rq = hctx->fq->flush_rq;
3521
3522         if (blk_mq_hw_queue_mapped(hctx))
3523                 blk_mq_tag_idle(hctx);
3524
3525         if (blk_queue_init_done(q))
3526                 blk_mq_clear_flush_rq_mapping(set->tags[hctx_idx],
3527                                 set->queue_depth, flush_rq);
3528         if (set->ops->exit_request)
3529                 set->ops->exit_request(set, flush_rq, hctx_idx);
3530
3531         if (set->ops->exit_hctx)
3532                 set->ops->exit_hctx(hctx, hctx_idx);
3533
3534         blk_mq_remove_cpuhp(hctx);
3535
3536         xa_erase(&q->hctx_table, hctx_idx);
3537
3538         spin_lock(&q->unused_hctx_lock);
3539         list_add(&hctx->hctx_list, &q->unused_hctx_list);
3540         spin_unlock(&q->unused_hctx_lock);
3541 }
3542
3543 static void blk_mq_exit_hw_queues(struct request_queue *q,
3544                 struct blk_mq_tag_set *set, int nr_queue)
3545 {
3546         struct blk_mq_hw_ctx *hctx;
3547         unsigned long i;
3548
3549         queue_for_each_hw_ctx(q, hctx, i) {
3550                 if (i == nr_queue)
3551                         break;
3552                 blk_mq_exit_hctx(q, set, hctx, i);
3553         }
3554 }
3555
3556 static int blk_mq_init_hctx(struct request_queue *q,
3557                 struct blk_mq_tag_set *set,
3558                 struct blk_mq_hw_ctx *hctx, unsigned hctx_idx)
3559 {
3560         hctx->queue_num = hctx_idx;
3561
3562         if (!(hctx->flags & BLK_MQ_F_STACKING))
3563                 cpuhp_state_add_instance_nocalls(CPUHP_AP_BLK_MQ_ONLINE,
3564                                 &hctx->cpuhp_online);
3565         cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD, &hctx->cpuhp_dead);
3566
3567         hctx->tags = set->tags[hctx_idx];
3568
3569         if (set->ops->init_hctx &&
3570             set->ops->init_hctx(hctx, set->driver_data, hctx_idx))
3571                 goto unregister_cpu_notifier;
3572
3573         if (blk_mq_init_request(set, hctx->fq->flush_rq, hctx_idx,
3574                                 hctx->numa_node))
3575                 goto exit_hctx;
3576
3577         if (xa_insert(&q->hctx_table, hctx_idx, hctx, GFP_KERNEL))
3578                 goto exit_flush_rq;
3579
3580         return 0;
3581
3582  exit_flush_rq:
3583         if (set->ops->exit_request)
3584                 set->ops->exit_request(set, hctx->fq->flush_rq, hctx_idx);
3585  exit_hctx:
3586         if (set->ops->exit_hctx)
3587                 set->ops->exit_hctx(hctx, hctx_idx);
3588  unregister_cpu_notifier:
3589         blk_mq_remove_cpuhp(hctx);
3590         return -1;
3591 }
3592
3593 static struct blk_mq_hw_ctx *
3594 blk_mq_alloc_hctx(struct request_queue *q, struct blk_mq_tag_set *set,
3595                 int node)
3596 {
3597         struct blk_mq_hw_ctx *hctx;
3598         gfp_t gfp = GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY;
3599
3600         hctx = kzalloc_node(sizeof(struct blk_mq_hw_ctx), gfp, node);
3601         if (!hctx)
3602                 goto fail_alloc_hctx;
3603
3604         if (!zalloc_cpumask_var_node(&hctx->cpumask, gfp, node))
3605                 goto free_hctx;
3606
3607         atomic_set(&hctx->nr_active, 0);
3608         if (node == NUMA_NO_NODE)
3609                 node = set->numa_node;
3610         hctx->numa_node = node;
3611
3612         INIT_DELAYED_WORK(&hctx->run_work, blk_mq_run_work_fn);
3613         spin_lock_init(&hctx->lock);
3614         INIT_LIST_HEAD(&hctx->dispatch);
3615         hctx->queue = q;
3616         hctx->flags = set->flags & ~BLK_MQ_F_TAG_QUEUE_SHARED;
3617
3618         INIT_LIST_HEAD(&hctx->hctx_list);
3619
3620         /*
3621          * Allocate space for all possible cpus to avoid allocation at
3622          * runtime
3623          */
3624         hctx->ctxs = kmalloc_array_node(nr_cpu_ids, sizeof(void *),
3625                         gfp, node);
3626         if (!hctx->ctxs)
3627                 goto free_cpumask;
3628
3629         if (sbitmap_init_node(&hctx->ctx_map, nr_cpu_ids, ilog2(8),
3630                                 gfp, node, false, false))
3631                 goto free_ctxs;
3632         hctx->nr_ctx = 0;
3633
3634         spin_lock_init(&hctx->dispatch_wait_lock);
3635         init_waitqueue_func_entry(&hctx->dispatch_wait, blk_mq_dispatch_wake);
3636         INIT_LIST_HEAD(&hctx->dispatch_wait.entry);
3637
3638         hctx->fq = blk_alloc_flush_queue(hctx->numa_node, set->cmd_size, gfp);
3639         if (!hctx->fq)
3640                 goto free_bitmap;
3641
3642         blk_mq_hctx_kobj_init(hctx);
3643
3644         return hctx;
3645
3646  free_bitmap:
3647         sbitmap_free(&hctx->ctx_map);
3648  free_ctxs:
3649         kfree(hctx->ctxs);
3650  free_cpumask:
3651         free_cpumask_var(hctx->cpumask);
3652  free_hctx:
3653         kfree(hctx);
3654  fail_alloc_hctx:
3655         return NULL;
3656 }
3657
3658 static void blk_mq_init_cpu_queues(struct request_queue *q,
3659                                    unsigned int nr_hw_queues)
3660 {
3661         struct blk_mq_tag_set *set = q->tag_set;
3662         unsigned int i, j;
3663
3664         for_each_possible_cpu(i) {
3665                 struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
3666                 struct blk_mq_hw_ctx *hctx;
3667                 int k;
3668
3669                 __ctx->cpu = i;
3670                 spin_lock_init(&__ctx->lock);
3671                 for (k = HCTX_TYPE_DEFAULT; k < HCTX_MAX_TYPES; k++)
3672                         INIT_LIST_HEAD(&__ctx->rq_lists[k]);
3673
3674                 __ctx->queue = q;
3675
3676                 /*
3677                  * Set local node, IFF we have more than one hw queue. If
3678                  * not, we remain on the home node of the device
3679                  */
3680                 for (j = 0; j < set->nr_maps; j++) {
3681                         hctx = blk_mq_map_queue_type(q, j, i);
3682                         if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE)
3683                                 hctx->numa_node = cpu_to_node(i);
3684                 }
3685         }
3686 }
3687
3688 struct blk_mq_tags *blk_mq_alloc_map_and_rqs(struct blk_mq_tag_set *set,
3689                                              unsigned int hctx_idx,
3690                                              unsigned int depth)
3691 {
3692         struct blk_mq_tags *tags;
3693         int ret;
3694
3695         tags = blk_mq_alloc_rq_map(set, hctx_idx, depth, set->reserved_tags);
3696         if (!tags)
3697                 return NULL;
3698
3699         ret = blk_mq_alloc_rqs(set, tags, hctx_idx, depth);
3700         if (ret) {
3701                 blk_mq_free_rq_map(tags);
3702                 return NULL;
3703         }
3704
3705         return tags;
3706 }
3707
3708 static bool __blk_mq_alloc_map_and_rqs(struct blk_mq_tag_set *set,
3709                                        int hctx_idx)
3710 {
3711         if (blk_mq_is_shared_tags(set->flags)) {
3712                 set->tags[hctx_idx] = set->shared_tags;
3713
3714                 return true;
3715         }
3716
3717         set->tags[hctx_idx] = blk_mq_alloc_map_and_rqs(set, hctx_idx,
3718                                                        set->queue_depth);
3719
3720         return set->tags[hctx_idx];
3721 }
3722
3723 void blk_mq_free_map_and_rqs(struct blk_mq_tag_set *set,
3724                              struct blk_mq_tags *tags,
3725                              unsigned int hctx_idx)
3726 {
3727         if (tags) {
3728                 blk_mq_free_rqs(set, tags, hctx_idx);
3729                 blk_mq_free_rq_map(tags);
3730         }
3731 }
3732
3733 static void __blk_mq_free_map_and_rqs(struct blk_mq_tag_set *set,
3734                                       unsigned int hctx_idx)
3735 {
3736         if (!blk_mq_is_shared_tags(set->flags))
3737                 blk_mq_free_map_and_rqs(set, set->tags[hctx_idx], hctx_idx);
3738
3739         set->tags[hctx_idx] = NULL;
3740 }
3741
3742 static void blk_mq_map_swqueue(struct request_queue *q)
3743 {
3744         unsigned int j, hctx_idx;
3745         unsigned long i;
3746         struct blk_mq_hw_ctx *hctx;
3747         struct blk_mq_ctx *ctx;
3748         struct blk_mq_tag_set *set = q->tag_set;
3749
3750         queue_for_each_hw_ctx(q, hctx, i) {
3751                 cpumask_clear(hctx->cpumask);
3752                 hctx->nr_ctx = 0;
3753                 hctx->dispatch_from = NULL;
3754         }
3755
3756         /*
3757          * Map software to hardware queues.
3758          *
3759          * If the cpu isn't present, the cpu is mapped to first hctx.
3760          */
3761         for_each_possible_cpu(i) {
3762
3763                 ctx = per_cpu_ptr(q->queue_ctx, i);
3764                 for (j = 0; j < set->nr_maps; j++) {
3765                         if (!set->map[j].nr_queues) {
3766                                 ctx->hctxs[j] = blk_mq_map_queue_type(q,
3767                                                 HCTX_TYPE_DEFAULT, i);
3768                                 continue;
3769                         }
3770                         hctx_idx = set->map[j].mq_map[i];
3771                         /* unmapped hw queue can be remapped after CPU topo changed */
3772                         if (!set->tags[hctx_idx] &&
3773                             !__blk_mq_alloc_map_and_rqs(set, hctx_idx)) {
3774                                 /*
3775                                  * If tags initialization fail for some hctx,
3776                                  * that hctx won't be brought online.  In this
3777                                  * case, remap the current ctx to hctx[0] which
3778                                  * is guaranteed to always have tags allocated
3779                                  */
3780                                 set->map[j].mq_map[i] = 0;
3781                         }
3782
3783                         hctx = blk_mq_map_queue_type(q, j, i);
3784                         ctx->hctxs[j] = hctx;
3785                         /*
3786                          * If the CPU is already set in the mask, then we've
3787                          * mapped this one already. This can happen if
3788                          * devices share queues across queue maps.
3789                          */
3790                         if (cpumask_test_cpu(i, hctx->cpumask))
3791                                 continue;
3792
3793                         cpumask_set_cpu(i, hctx->cpumask);
3794                         hctx->type = j;
3795                         ctx->index_hw[hctx->type] = hctx->nr_ctx;
3796                         hctx->ctxs[hctx->nr_ctx++] = ctx;
3797
3798                         /*
3799                          * If the nr_ctx type overflows, we have exceeded the
3800                          * amount of sw queues we can support.
3801                          */
3802                         BUG_ON(!hctx->nr_ctx);
3803                 }
3804
3805                 for (; j < HCTX_MAX_TYPES; j++)
3806                         ctx->hctxs[j] = blk_mq_map_queue_type(q,
3807                                         HCTX_TYPE_DEFAULT, i);
3808         }
3809
3810         queue_for_each_hw_ctx(q, hctx, i) {
3811                 /*
3812                  * If no software queues are mapped to this hardware queue,
3813                  * disable it and free the request entries.
3814                  */
3815                 if (!hctx->nr_ctx) {
3816                         /* Never unmap queue 0.  We need it as a
3817                          * fallback in case of a new remap fails
3818                          * allocation
3819                          */
3820                         if (i)
3821                                 __blk_mq_free_map_and_rqs(set, i);
3822
3823                         hctx->tags = NULL;
3824                         continue;
3825                 }
3826
3827                 hctx->tags = set->tags[i];
3828                 WARN_ON(!hctx->tags);
3829
3830                 /*
3831                  * Set the map size to the number of mapped software queues.
3832                  * This is more accurate and more efficient than looping
3833                  * over all possibly mapped software queues.
3834                  */
3835                 sbitmap_resize(&hctx->ctx_map, hctx->nr_ctx);
3836
3837                 /*
3838                  * Initialize batch roundrobin counts
3839                  */
3840                 hctx->next_cpu = blk_mq_first_mapped_cpu(hctx);
3841                 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
3842         }
3843 }
3844
3845 /*
3846  * Caller needs to ensure that we're either frozen/quiesced, or that
3847  * the queue isn't live yet.
3848  */
3849 static void queue_set_hctx_shared(struct request_queue *q, bool shared)
3850 {
3851         struct blk_mq_hw_ctx *hctx;
3852         unsigned long i;
3853
3854         queue_for_each_hw_ctx(q, hctx, i) {
3855                 if (shared) {
3856                         hctx->flags |= BLK_MQ_F_TAG_QUEUE_SHARED;
3857                 } else {
3858                         blk_mq_tag_idle(hctx);
3859                         hctx->flags &= ~BLK_MQ_F_TAG_QUEUE_SHARED;
3860                 }
3861         }
3862 }
3863
3864 static void blk_mq_update_tag_set_shared(struct blk_mq_tag_set *set,
3865                                          bool shared)
3866 {
3867         struct request_queue *q;
3868
3869         lockdep_assert_held(&set->tag_list_lock);
3870
3871         list_for_each_entry(q, &set->tag_list, tag_set_list) {
3872                 blk_mq_freeze_queue(q);
3873                 queue_set_hctx_shared(q, shared);
3874                 blk_mq_unfreeze_queue(q);
3875         }
3876 }
3877
3878 static void blk_mq_del_queue_tag_set(struct request_queue *q)
3879 {
3880         struct blk_mq_tag_set *set = q->tag_set;
3881
3882         mutex_lock(&set->tag_list_lock);
3883         list_del(&q->tag_set_list);
3884         if (list_is_singular(&set->tag_list)) {
3885                 /* just transitioned to unshared */
3886                 set->flags &= ~BLK_MQ_F_TAG_QUEUE_SHARED;
3887                 /* update existing queue */
3888                 blk_mq_update_tag_set_shared(set, false);
3889         }
3890         mutex_unlock(&set->tag_list_lock);
3891         INIT_LIST_HEAD(&q->tag_set_list);
3892 }
3893
3894 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
3895                                      struct request_queue *q)
3896 {
3897         mutex_lock(&set->tag_list_lock);
3898
3899         /*
3900          * Check to see if we're transitioning to shared (from 1 to 2 queues).
3901          */
3902         if (!list_empty(&set->tag_list) &&
3903             !(set->flags & BLK_MQ_F_TAG_QUEUE_SHARED)) {
3904                 set->flags |= BLK_MQ_F_TAG_QUEUE_SHARED;
3905                 /* update existing queue */
3906                 blk_mq_update_tag_set_shared(set, true);
3907         }
3908         if (set->flags & BLK_MQ_F_TAG_QUEUE_SHARED)
3909                 queue_set_hctx_shared(q, true);
3910         list_add_tail(&q->tag_set_list, &set->tag_list);
3911
3912         mutex_unlock(&set->tag_list_lock);
3913 }
3914
3915 /* All allocations will be freed in release handler of q->mq_kobj */
3916 static int blk_mq_alloc_ctxs(struct request_queue *q)
3917 {
3918         struct blk_mq_ctxs *ctxs;
3919         int cpu;
3920
3921         ctxs = kzalloc(sizeof(*ctxs), GFP_KERNEL);
3922         if (!ctxs)
3923                 return -ENOMEM;
3924
3925         ctxs->queue_ctx = alloc_percpu(struct blk_mq_ctx);
3926         if (!ctxs->queue_ctx)
3927                 goto fail;
3928
3929         for_each_possible_cpu(cpu) {
3930                 struct blk_mq_ctx *ctx = per_cpu_ptr(ctxs->queue_ctx, cpu);
3931                 ctx->ctxs = ctxs;
3932         }
3933
3934         q->mq_kobj = &ctxs->kobj;
3935         q->queue_ctx = ctxs->queue_ctx;
3936
3937         return 0;
3938  fail:
3939         kfree(ctxs);
3940         return -ENOMEM;
3941 }
3942
3943 /*
3944  * It is the actual release handler for mq, but we do it from
3945  * request queue's release handler for avoiding use-after-free
3946  * and headache because q->mq_kobj shouldn't have been introduced,
3947  * but we can't group ctx/kctx kobj without it.
3948  */
3949 void blk_mq_release(struct request_queue *q)
3950 {
3951         struct blk_mq_hw_ctx *hctx, *next;
3952         unsigned long i;
3953
3954         queue_for_each_hw_ctx(q, hctx, i)
3955                 WARN_ON_ONCE(hctx && list_empty(&hctx->hctx_list));
3956
3957         /* all hctx are in .unused_hctx_list now */
3958         list_for_each_entry_safe(hctx, next, &q->unused_hctx_list, hctx_list) {
3959                 list_del_init(&hctx->hctx_list);
3960                 kobject_put(&hctx->kobj);
3961         }
3962
3963         xa_destroy(&q->hctx_table);
3964
3965         /*
3966          * release .mq_kobj and sw queue's kobject now because
3967          * both share lifetime with request queue.
3968          */
3969         blk_mq_sysfs_deinit(q);
3970 }
3971
3972 static struct request_queue *blk_mq_init_queue_data(struct blk_mq_tag_set *set,
3973                 void *queuedata)
3974 {
3975         struct request_queue *q;
3976         int ret;
3977
3978         q = blk_alloc_queue(set->numa_node, set->flags & BLK_MQ_F_BLOCKING);
3979         if (!q)
3980                 return ERR_PTR(-ENOMEM);
3981         q->queuedata = queuedata;
3982         ret = blk_mq_init_allocated_queue(set, q);
3983         if (ret) {
3984                 blk_put_queue(q);
3985                 return ERR_PTR(ret);
3986         }
3987         return q;
3988 }
3989
3990 struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
3991 {
3992         return blk_mq_init_queue_data(set, NULL);
3993 }
3994 EXPORT_SYMBOL(blk_mq_init_queue);
3995
3996 /**
3997  * blk_mq_destroy_queue - shutdown a request queue
3998  * @q: request queue to shutdown
3999  *
4000  * This shuts down a request queue allocated by blk_mq_init_queue() and drops
4001  * the initial reference.  All future requests will failed with -ENODEV.
4002  *
4003  * Context: can sleep
4004  */
4005 void blk_mq_destroy_queue(struct request_queue *q)
4006 {
4007         WARN_ON_ONCE(!queue_is_mq(q));
4008         WARN_ON_ONCE(blk_queue_registered(q));
4009
4010         might_sleep();
4011
4012         blk_queue_flag_set(QUEUE_FLAG_DYING, q);
4013         blk_queue_start_drain(q);
4014         blk_freeze_queue(q);
4015
4016         blk_sync_queue(q);
4017         blk_mq_cancel_work_sync(q);
4018         blk_mq_exit_queue(q);
4019
4020         /* @q is and will stay empty, shutdown and put */
4021         blk_put_queue(q);
4022 }
4023 EXPORT_SYMBOL(blk_mq_destroy_queue);
4024
4025 struct gendisk *__blk_mq_alloc_disk(struct blk_mq_tag_set *set, void *queuedata,
4026                 struct lock_class_key *lkclass)
4027 {
4028         struct request_queue *q;
4029         struct gendisk *disk;
4030
4031         q = blk_mq_init_queue_data(set, queuedata);
4032         if (IS_ERR(q))
4033                 return ERR_CAST(q);
4034
4035         disk = __alloc_disk_node(q, set->numa_node, lkclass);
4036         if (!disk) {
4037                 blk_mq_destroy_queue(q);
4038                 return ERR_PTR(-ENOMEM);
4039         }
4040         set_bit(GD_OWNS_QUEUE, &disk->state);
4041         return disk;
4042 }
4043 EXPORT_SYMBOL(__blk_mq_alloc_disk);
4044
4045 struct gendisk *blk_mq_alloc_disk_for_queue(struct request_queue *q,
4046                 struct lock_class_key *lkclass)
4047 {
4048         struct gendisk *disk;
4049
4050         if (!blk_get_queue(q))
4051                 return NULL;
4052         disk = __alloc_disk_node(q, NUMA_NO_NODE, lkclass);
4053         if (!disk)
4054                 blk_put_queue(q);
4055         return disk;
4056 }
4057 EXPORT_SYMBOL(blk_mq_alloc_disk_for_queue);
4058
4059 static struct blk_mq_hw_ctx *blk_mq_alloc_and_init_hctx(
4060                 struct blk_mq_tag_set *set, struct request_queue *q,
4061                 int hctx_idx, int node)
4062 {
4063         struct blk_mq_hw_ctx *hctx = NULL, *tmp;
4064
4065         /* reuse dead hctx first */
4066         spin_lock(&q->unused_hctx_lock);
4067         list_for_each_entry(tmp, &q->unused_hctx_list, hctx_list) {
4068                 if (tmp->numa_node == node) {
4069                         hctx = tmp;
4070                         break;
4071                 }
4072         }
4073         if (hctx)
4074                 list_del_init(&hctx->hctx_list);
4075         spin_unlock(&q->unused_hctx_lock);
4076
4077         if (!hctx)
4078                 hctx = blk_mq_alloc_hctx(q, set, node);
4079         if (!hctx)
4080                 goto fail;
4081
4082         if (blk_mq_init_hctx(q, set, hctx, hctx_idx))
4083                 goto free_hctx;
4084
4085         return hctx;
4086
4087  free_hctx:
4088         kobject_put(&hctx->kobj);
4089  fail:
4090         return NULL;
4091 }
4092
4093 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
4094                                                 struct request_queue *q)
4095 {
4096         struct blk_mq_hw_ctx *hctx;
4097         unsigned long i, j;
4098
4099         /* protect against switching io scheduler  */
4100         mutex_lock(&q->sysfs_lock);
4101         for (i = 0; i < set->nr_hw_queues; i++) {
4102                 int old_node;
4103                 int node = blk_mq_get_hctx_node(set, i);
4104                 struct blk_mq_hw_ctx *old_hctx = xa_load(&q->hctx_table, i);
4105
4106                 if (old_hctx) {
4107                         old_node = old_hctx->numa_node;
4108                         blk_mq_exit_hctx(q, set, old_hctx, i);
4109                 }
4110
4111                 if (!blk_mq_alloc_and_init_hctx(set, q, i, node)) {
4112                         if (!old_hctx)
4113                                 break;
4114                         pr_warn("Allocate new hctx on node %d fails, fallback to previous one on node %d\n",
4115                                         node, old_node);
4116                         hctx = blk_mq_alloc_and_init_hctx(set, q, i, old_node);
4117                         WARN_ON_ONCE(!hctx);
4118                 }
4119         }
4120         /*
4121          * Increasing nr_hw_queues fails. Free the newly allocated
4122          * hctxs and keep the previous q->nr_hw_queues.
4123          */
4124         if (i != set->nr_hw_queues) {
4125                 j = q->nr_hw_queues;
4126         } else {
4127                 j = i;
4128                 q->nr_hw_queues = set->nr_hw_queues;
4129         }
4130
4131         xa_for_each_start(&q->hctx_table, j, hctx, j)
4132                 blk_mq_exit_hctx(q, set, hctx, j);
4133         mutex_unlock(&q->sysfs_lock);
4134 }
4135
4136 static void blk_mq_update_poll_flag(struct request_queue *q)
4137 {
4138         struct blk_mq_tag_set *set = q->tag_set;
4139
4140         if (set->nr_maps > HCTX_TYPE_POLL &&
4141             set->map[HCTX_TYPE_POLL].nr_queues)
4142                 blk_queue_flag_set(QUEUE_FLAG_POLL, q);
4143         else
4144                 blk_queue_flag_clear(QUEUE_FLAG_POLL, q);
4145 }
4146
4147 int blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
4148                 struct request_queue *q)
4149 {
4150         WARN_ON_ONCE(blk_queue_has_srcu(q) !=
4151                         !!(set->flags & BLK_MQ_F_BLOCKING));
4152
4153         /* mark the queue as mq asap */
4154         q->mq_ops = set->ops;
4155
4156         q->poll_cb = blk_stat_alloc_callback(blk_mq_poll_stats_fn,
4157                                              blk_mq_poll_stats_bkt,
4158                                              BLK_MQ_POLL_STATS_BKTS, q);
4159         if (!q->poll_cb)
4160                 goto err_exit;
4161
4162         if (blk_mq_alloc_ctxs(q))
4163                 goto err_poll;
4164
4165         /* init q->mq_kobj and sw queues' kobjects */
4166         blk_mq_sysfs_init(q);
4167
4168         INIT_LIST_HEAD(&q->unused_hctx_list);
4169         spin_lock_init(&q->unused_hctx_lock);
4170
4171         xa_init(&q->hctx_table);
4172
4173         blk_mq_realloc_hw_ctxs(set, q);
4174         if (!q->nr_hw_queues)
4175                 goto err_hctxs;
4176
4177         INIT_WORK(&q->timeout_work, blk_mq_timeout_work);
4178         blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);
4179
4180         q->tag_set = set;
4181
4182         q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
4183         blk_mq_update_poll_flag(q);
4184
4185         INIT_DELAYED_WORK(&q->requeue_work, blk_mq_requeue_work);
4186         INIT_LIST_HEAD(&q->requeue_list);
4187         spin_lock_init(&q->requeue_lock);
4188
4189         q->nr_requests = set->queue_depth;
4190
4191         /*
4192          * Default to classic polling
4193          */
4194         q->poll_nsec = BLK_MQ_POLL_CLASSIC;
4195
4196         blk_mq_init_cpu_queues(q, set->nr_hw_queues);
4197         blk_mq_add_queue_tag_set(set, q);
4198         blk_mq_map_swqueue(q);
4199         return 0;
4200
4201 err_hctxs:
4202         blk_mq_release(q);
4203 err_poll:
4204         blk_stat_free_callback(q->poll_cb);
4205         q->poll_cb = NULL;
4206 err_exit:
4207         q->mq_ops = NULL;
4208         return -ENOMEM;
4209 }
4210 EXPORT_SYMBOL(blk_mq_init_allocated_queue);
4211
4212 /* tags can _not_ be used after returning from blk_mq_exit_queue */
4213 void blk_mq_exit_queue(struct request_queue *q)
4214 {
4215         struct blk_mq_tag_set *set = q->tag_set;
4216
4217         /* Checks hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED. */
4218         blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
4219         /* May clear BLK_MQ_F_TAG_QUEUE_SHARED in hctx->flags. */
4220         blk_mq_del_queue_tag_set(q);
4221 }
4222
4223 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
4224 {
4225         int i;
4226
4227         if (blk_mq_is_shared_tags(set->flags)) {
4228                 set->shared_tags = blk_mq_alloc_map_and_rqs(set,
4229                                                 BLK_MQ_NO_HCTX_IDX,
4230                                                 set->queue_depth);
4231                 if (!set->shared_tags)
4232                         return -ENOMEM;
4233         }
4234
4235         for (i = 0; i < set->nr_hw_queues; i++) {
4236                 if (!__blk_mq_alloc_map_and_rqs(set, i))
4237                         goto out_unwind;
4238                 cond_resched();
4239         }
4240
4241         return 0;
4242
4243 out_unwind:
4244         while (--i >= 0)
4245                 __blk_mq_free_map_and_rqs(set, i);
4246
4247         if (blk_mq_is_shared_tags(set->flags)) {
4248                 blk_mq_free_map_and_rqs(set, set->shared_tags,
4249                                         BLK_MQ_NO_HCTX_IDX);
4250         }
4251
4252         return -ENOMEM;
4253 }
4254
4255 /*
4256  * Allocate the request maps associated with this tag_set. Note that this
4257  * may reduce the depth asked for, if memory is tight. set->queue_depth
4258  * will be updated to reflect the allocated depth.
4259  */
4260 static int blk_mq_alloc_set_map_and_rqs(struct blk_mq_tag_set *set)
4261 {
4262         unsigned int depth;
4263         int err;
4264
4265         depth = set->queue_depth;
4266         do {
4267                 err = __blk_mq_alloc_rq_maps(set);
4268                 if (!err)
4269                         break;
4270
4271                 set->queue_depth >>= 1;
4272                 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN) {
4273                         err = -ENOMEM;
4274                         break;
4275                 }
4276         } while (set->queue_depth);
4277
4278         if (!set->queue_depth || err) {
4279                 pr_err("blk-mq: failed to allocate request map\n");
4280                 return -ENOMEM;
4281         }
4282
4283         if (depth != set->queue_depth)
4284                 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
4285                                                 depth, set->queue_depth);
4286
4287         return 0;
4288 }
4289
4290 static void blk_mq_update_queue_map(struct blk_mq_tag_set *set)
4291 {
4292         /*
4293          * blk_mq_map_queues() and multiple .map_queues() implementations
4294          * expect that set->map[HCTX_TYPE_DEFAULT].nr_queues is set to the
4295          * number of hardware queues.
4296          */
4297         if (set->nr_maps == 1)
4298                 set->map[HCTX_TYPE_DEFAULT].nr_queues = set->nr_hw_queues;
4299
4300         if (set->ops->map_queues && !is_kdump_kernel()) {
4301                 int i;
4302
4303                 /*
4304                  * transport .map_queues is usually done in the following
4305                  * way:
4306                  *
4307                  * for (queue = 0; queue < set->nr_hw_queues; queue++) {
4308                  *      mask = get_cpu_mask(queue)
4309                  *      for_each_cpu(cpu, mask)
4310                  *              set->map[x].mq_map[cpu] = queue;
4311                  * }
4312                  *
4313                  * When we need to remap, the table has to be cleared for
4314                  * killing stale mapping since one CPU may not be mapped
4315                  * to any hw queue.
4316                  */
4317                 for (i = 0; i < set->nr_maps; i++)
4318                         blk_mq_clear_mq_map(&set->map[i]);
4319
4320                 set->ops->map_queues(set);
4321         } else {
4322                 BUG_ON(set->nr_maps > 1);
4323                 blk_mq_map_queues(&set->map[HCTX_TYPE_DEFAULT]);
4324         }
4325 }
4326
4327 static int blk_mq_realloc_tag_set_tags(struct blk_mq_tag_set *set,
4328                                   int cur_nr_hw_queues, int new_nr_hw_queues)
4329 {
4330         struct blk_mq_tags **new_tags;
4331
4332         if (cur_nr_hw_queues >= new_nr_hw_queues)
4333                 return 0;
4334
4335         new_tags = kcalloc_node(new_nr_hw_queues, sizeof(struct blk_mq_tags *),
4336                                 GFP_KERNEL, set->numa_node);
4337         if (!new_tags)
4338                 return -ENOMEM;
4339
4340         if (set->tags)
4341                 memcpy(new_tags, set->tags, cur_nr_hw_queues *
4342                        sizeof(*set->tags));
4343         kfree(set->tags);
4344         set->tags = new_tags;
4345         set->nr_hw_queues = new_nr_hw_queues;
4346
4347         return 0;
4348 }
4349
4350 static int blk_mq_alloc_tag_set_tags(struct blk_mq_tag_set *set,
4351                                 int new_nr_hw_queues)
4352 {
4353         return blk_mq_realloc_tag_set_tags(set, 0, new_nr_hw_queues);
4354 }
4355
4356 /*
4357  * Alloc a tag set to be associated with one or more request queues.
4358  * May fail with EINVAL for various error conditions. May adjust the
4359  * requested depth down, if it's too large. In that case, the set
4360  * value will be stored in set->queue_depth.
4361  */
4362 int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
4363 {
4364         int i, ret;
4365
4366         BUILD_BUG_ON(BLK_MQ_MAX_DEPTH > 1 << BLK_MQ_UNIQUE_TAG_BITS);
4367
4368         if (!set->nr_hw_queues)
4369                 return -EINVAL;
4370         if (!set->queue_depth)
4371                 return -EINVAL;
4372         if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN)
4373                 return -EINVAL;
4374
4375         if (!set->ops->queue_rq)
4376                 return -EINVAL;
4377
4378         if (!set->ops->get_budget ^ !set->ops->put_budget)
4379                 return -EINVAL;
4380
4381         if (set->queue_depth > BLK_MQ_MAX_DEPTH) {
4382                 pr_info("blk-mq: reduced tag depth to %u\n",
4383                         BLK_MQ_MAX_DEPTH);
4384                 set->queue_depth = BLK_MQ_MAX_DEPTH;
4385         }
4386
4387         if (!set->nr_maps)
4388                 set->nr_maps = 1;
4389         else if (set->nr_maps > HCTX_MAX_TYPES)
4390                 return -EINVAL;
4391
4392         /*
4393          * If a crashdump is active, then we are potentially in a very
4394          * memory constrained environment. Limit us to 1 queue and
4395          * 64 tags to prevent using too much memory.
4396          */
4397         if (is_kdump_kernel()) {
4398                 set->nr_hw_queues = 1;
4399                 set->nr_maps = 1;
4400                 set->queue_depth = min(64U, set->queue_depth);
4401         }
4402         /*
4403          * There is no use for more h/w queues than cpus if we just have
4404          * a single map
4405          */
4406         if (set->nr_maps == 1 && set->nr_hw_queues > nr_cpu_ids)
4407                 set->nr_hw_queues = nr_cpu_ids;
4408
4409         if (blk_mq_alloc_tag_set_tags(set, set->nr_hw_queues) < 0)
4410                 return -ENOMEM;
4411
4412         ret = -ENOMEM;
4413         for (i = 0; i < set->nr_maps; i++) {
4414                 set->map[i].mq_map = kcalloc_node(nr_cpu_ids,
4415                                                   sizeof(set->map[i].mq_map[0]),
4416                                                   GFP_KERNEL, set->numa_node);
4417                 if (!set->map[i].mq_map)
4418                         goto out_free_mq_map;
4419                 set->map[i].nr_queues = is_kdump_kernel() ? 1 : set->nr_hw_queues;
4420         }
4421
4422         blk_mq_update_queue_map(set);
4423
4424         ret = blk_mq_alloc_set_map_and_rqs(set);
4425         if (ret)
4426                 goto out_free_mq_map;
4427
4428         mutex_init(&set->tag_list_lock);
4429         INIT_LIST_HEAD(&set->tag_list);
4430
4431         return 0;
4432
4433 out_free_mq_map:
4434         for (i = 0; i < set->nr_maps; i++) {
4435                 kfree(set->map[i].mq_map);
4436                 set->map[i].mq_map = NULL;
4437         }
4438         kfree(set->tags);
4439         set->tags = NULL;
4440         return ret;
4441 }
4442 EXPORT_SYMBOL(blk_mq_alloc_tag_set);
4443
4444 /* allocate and initialize a tagset for a simple single-queue device */
4445 int blk_mq_alloc_sq_tag_set(struct blk_mq_tag_set *set,
4446                 const struct blk_mq_ops *ops, unsigned int queue_depth,
4447                 unsigned int set_flags)
4448 {
4449         memset(set, 0, sizeof(*set));
4450         set->ops = ops;
4451         set->nr_hw_queues = 1;
4452         set->nr_maps = 1;
4453         set->queue_depth = queue_depth;
4454         set->numa_node = NUMA_NO_NODE;
4455         set->flags = set_flags;
4456         return blk_mq_alloc_tag_set(set);
4457 }
4458 EXPORT_SYMBOL_GPL(blk_mq_alloc_sq_tag_set);
4459
4460 void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
4461 {
4462         int i, j;
4463
4464         for (i = 0; i < set->nr_hw_queues; i++)
4465                 __blk_mq_free_map_and_rqs(set, i);
4466
4467         if (blk_mq_is_shared_tags(set->flags)) {
4468                 blk_mq_free_map_and_rqs(set, set->shared_tags,
4469                                         BLK_MQ_NO_HCTX_IDX);
4470         }
4471
4472         for (j = 0; j < set->nr_maps; j++) {
4473                 kfree(set->map[j].mq_map);
4474                 set->map[j].mq_map = NULL;
4475         }
4476
4477         kfree(set->tags);
4478         set->tags = NULL;
4479 }
4480 EXPORT_SYMBOL(blk_mq_free_tag_set);
4481
4482 int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
4483 {
4484         struct blk_mq_tag_set *set = q->tag_set;
4485         struct blk_mq_hw_ctx *hctx;
4486         int ret;
4487         unsigned long i;
4488
4489         if (!set)
4490                 return -EINVAL;
4491
4492         if (q->nr_requests == nr)
4493                 return 0;
4494
4495         blk_mq_freeze_queue(q);
4496         blk_mq_quiesce_queue(q);
4497
4498         ret = 0;
4499         queue_for_each_hw_ctx(q, hctx, i) {
4500                 if (!hctx->tags)
4501                         continue;
4502                 /*
4503                  * If we're using an MQ scheduler, just update the scheduler
4504                  * queue depth. This is similar to what the old code would do.
4505                  */
4506                 if (hctx->sched_tags) {
4507                         ret = blk_mq_tag_update_depth(hctx, &hctx->sched_tags,
4508                                                       nr, true);
4509                 } else {
4510                         ret = blk_mq_tag_update_depth(hctx, &hctx->tags, nr,
4511                                                       false);
4512                 }
4513                 if (ret)
4514                         break;
4515                 if (q->elevator && q->elevator->type->ops.depth_updated)
4516                         q->elevator->type->ops.depth_updated(hctx);
4517         }
4518         if (!ret) {
4519                 q->nr_requests = nr;
4520                 if (blk_mq_is_shared_tags(set->flags)) {
4521                         if (q->elevator)
4522                                 blk_mq_tag_update_sched_shared_tags(q);
4523                         else
4524                                 blk_mq_tag_resize_shared_tags(set, nr);
4525                 }
4526         }
4527
4528         blk_mq_unquiesce_queue(q);
4529         blk_mq_unfreeze_queue(q);
4530
4531         return ret;
4532 }
4533
4534 /*
4535  * request_queue and elevator_type pair.
4536  * It is just used by __blk_mq_update_nr_hw_queues to cache
4537  * the elevator_type associated with a request_queue.
4538  */
4539 struct blk_mq_qe_pair {
4540         struct list_head node;
4541         struct request_queue *q;
4542         struct elevator_type *type;
4543 };
4544
4545 /*
4546  * Cache the elevator_type in qe pair list and switch the
4547  * io scheduler to 'none'
4548  */
4549 static bool blk_mq_elv_switch_none(struct list_head *head,
4550                 struct request_queue *q)
4551 {
4552         struct blk_mq_qe_pair *qe;
4553
4554         if (!q->elevator)
4555                 return true;
4556
4557         qe = kmalloc(sizeof(*qe), GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY);
4558         if (!qe)
4559                 return false;
4560
4561         /* q->elevator needs protection from ->sysfs_lock */
4562         mutex_lock(&q->sysfs_lock);
4563
4564         INIT_LIST_HEAD(&qe->node);
4565         qe->q = q;
4566         qe->type = q->elevator->type;
4567         list_add(&qe->node, head);
4568
4569         /*
4570          * After elevator_switch, the previous elevator_queue will be
4571          * released by elevator_release. The reference of the io scheduler
4572          * module get by elevator_get will also be put. So we need to get
4573          * a reference of the io scheduler module here to prevent it to be
4574          * removed.
4575          */
4576         __module_get(qe->type->elevator_owner);
4577         elevator_switch(q, NULL);
4578         mutex_unlock(&q->sysfs_lock);
4579
4580         return true;
4581 }
4582
4583 static struct blk_mq_qe_pair *blk_lookup_qe_pair(struct list_head *head,
4584                                                 struct request_queue *q)
4585 {
4586         struct blk_mq_qe_pair *qe;
4587
4588         list_for_each_entry(qe, head, node)
4589                 if (qe->q == q)
4590                         return qe;
4591
4592         return NULL;
4593 }
4594
4595 static void blk_mq_elv_switch_back(struct list_head *head,
4596                                   struct request_queue *q)
4597 {
4598         struct blk_mq_qe_pair *qe;
4599         struct elevator_type *t;
4600
4601         qe = blk_lookup_qe_pair(head, q);
4602         if (!qe)
4603                 return;
4604         t = qe->type;
4605         list_del(&qe->node);
4606         kfree(qe);
4607
4608         mutex_lock(&q->sysfs_lock);
4609         elevator_switch(q, t);
4610         mutex_unlock(&q->sysfs_lock);
4611 }
4612
4613 static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set,
4614                                                         int nr_hw_queues)
4615 {
4616         struct request_queue *q;
4617         LIST_HEAD(head);
4618         int prev_nr_hw_queues;
4619
4620         lockdep_assert_held(&set->tag_list_lock);
4621
4622         if (set->nr_maps == 1 && nr_hw_queues > nr_cpu_ids)
4623                 nr_hw_queues = nr_cpu_ids;
4624         if (nr_hw_queues < 1)
4625                 return;
4626         if (set->nr_maps == 1 && nr_hw_queues == set->nr_hw_queues)
4627                 return;
4628
4629         list_for_each_entry(q, &set->tag_list, tag_set_list)
4630                 blk_mq_freeze_queue(q);
4631         /*
4632          * Switch IO scheduler to 'none', cleaning up the data associated
4633          * with the previous scheduler. We will switch back once we are done
4634          * updating the new sw to hw queue mappings.
4635          */
4636         list_for_each_entry(q, &set->tag_list, tag_set_list)
4637                 if (!blk_mq_elv_switch_none(&head, q))
4638                         goto switch_back;
4639
4640         list_for_each_entry(q, &set->tag_list, tag_set_list) {
4641                 blk_mq_debugfs_unregister_hctxs(q);
4642                 blk_mq_sysfs_unregister_hctxs(q);
4643         }
4644
4645         prev_nr_hw_queues = set->nr_hw_queues;
4646         if (blk_mq_realloc_tag_set_tags(set, set->nr_hw_queues, nr_hw_queues) <
4647             0)
4648                 goto reregister;
4649
4650         set->nr_hw_queues = nr_hw_queues;
4651 fallback:
4652         blk_mq_update_queue_map(set);
4653         list_for_each_entry(q, &set->tag_list, tag_set_list) {
4654                 blk_mq_realloc_hw_ctxs(set, q);
4655                 blk_mq_update_poll_flag(q);
4656                 if (q->nr_hw_queues != set->nr_hw_queues) {
4657                         int i = prev_nr_hw_queues;
4658
4659                         pr_warn("Increasing nr_hw_queues to %d fails, fallback to %d\n",
4660                                         nr_hw_queues, prev_nr_hw_queues);
4661                         for (; i < set->nr_hw_queues; i++)
4662                                 __blk_mq_free_map_and_rqs(set, i);
4663
4664                         set->nr_hw_queues = prev_nr_hw_queues;
4665                         blk_mq_map_queues(&set->map[HCTX_TYPE_DEFAULT]);
4666                         goto fallback;
4667                 }
4668                 blk_mq_map_swqueue(q);
4669         }
4670
4671 reregister:
4672         list_for_each_entry(q, &set->tag_list, tag_set_list) {
4673                 blk_mq_sysfs_register_hctxs(q);
4674                 blk_mq_debugfs_register_hctxs(q);
4675         }
4676
4677 switch_back:
4678         list_for_each_entry(q, &set->tag_list, tag_set_list)
4679                 blk_mq_elv_switch_back(&head, q);
4680
4681         list_for_each_entry(q, &set->tag_list, tag_set_list)
4682                 blk_mq_unfreeze_queue(q);
4683 }
4684
4685 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
4686 {
4687         mutex_lock(&set->tag_list_lock);
4688         __blk_mq_update_nr_hw_queues(set, nr_hw_queues);
4689         mutex_unlock(&set->tag_list_lock);
4690 }
4691 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues);
4692
4693 /* Enable polling stats and return whether they were already enabled. */
4694 static bool blk_poll_stats_enable(struct request_queue *q)
4695 {
4696         if (q->poll_stat)
4697                 return true;
4698
4699         return blk_stats_alloc_enable(q);
4700 }
4701
4702 static void blk_mq_poll_stats_start(struct request_queue *q)
4703 {
4704         /*
4705          * We don't arm the callback if polling stats are not enabled or the
4706          * callback is already active.
4707          */
4708         if (!q->poll_stat || blk_stat_is_active(q->poll_cb))
4709                 return;
4710
4711         blk_stat_activate_msecs(q->poll_cb, 100);
4712 }
4713
4714 static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb)
4715 {
4716         struct request_queue *q = cb->data;
4717         int bucket;
4718
4719         for (bucket = 0; bucket < BLK_MQ_POLL_STATS_BKTS; bucket++) {
4720                 if (cb->stat[bucket].nr_samples)
4721                         q->poll_stat[bucket] = cb->stat[bucket];
4722         }
4723 }
4724
4725 static unsigned long blk_mq_poll_nsecs(struct request_queue *q,
4726                                        struct request *rq)
4727 {
4728         unsigned long ret = 0;
4729         int bucket;
4730
4731         /*
4732          * If stats collection isn't on, don't sleep but turn it on for
4733          * future users
4734          */
4735         if (!blk_poll_stats_enable(q))
4736                 return 0;
4737
4738         /*
4739          * As an optimistic guess, use half of the mean service time
4740          * for this type of request. We can (and should) make this smarter.
4741          * For instance, if the completion latencies are tight, we can
4742          * get closer than just half the mean. This is especially
4743          * important on devices where the completion latencies are longer
4744          * than ~10 usec. We do use the stats for the relevant IO size
4745          * if available which does lead to better estimates.
4746          */
4747         bucket = blk_mq_poll_stats_bkt(rq);
4748         if (bucket < 0)
4749                 return ret;
4750
4751         if (q->poll_stat[bucket].nr_samples)
4752                 ret = (q->poll_stat[bucket].mean + 1) / 2;
4753
4754         return ret;
4755 }
4756
4757 static bool blk_mq_poll_hybrid(struct request_queue *q, blk_qc_t qc)
4758 {
4759         struct blk_mq_hw_ctx *hctx = blk_qc_to_hctx(q, qc);
4760         struct request *rq = blk_qc_to_rq(hctx, qc);
4761         struct hrtimer_sleeper hs;
4762         enum hrtimer_mode mode;
4763         unsigned int nsecs;
4764         ktime_t kt;
4765
4766         /*
4767          * If a request has completed on queue that uses an I/O scheduler, we
4768          * won't get back a request from blk_qc_to_rq.
4769          */
4770         if (!rq || (rq->rq_flags & RQF_MQ_POLL_SLEPT))
4771                 return false;
4772
4773         /*
4774          * If we get here, hybrid polling is enabled. Hence poll_nsec can be:
4775          *
4776          *  0:  use half of prev avg
4777          * >0:  use this specific value
4778          */
4779         if (q->poll_nsec > 0)
4780                 nsecs = q->poll_nsec;
4781         else
4782                 nsecs = blk_mq_poll_nsecs(q, rq);
4783
4784         if (!nsecs)
4785                 return false;
4786
4787         rq->rq_flags |= RQF_MQ_POLL_SLEPT;
4788
4789         /*
4790          * This will be replaced with the stats tracking code, using
4791          * 'avg_completion_time / 2' as the pre-sleep target.
4792          */
4793         kt = nsecs;
4794
4795         mode = HRTIMER_MODE_REL;
4796         hrtimer_init_sleeper_on_stack(&hs, CLOCK_MONOTONIC, mode);
4797         hrtimer_set_expires(&hs.timer, kt);
4798
4799         do {
4800                 if (blk_mq_rq_state(rq) == MQ_RQ_COMPLETE)
4801                         break;
4802                 set_current_state(TASK_UNINTERRUPTIBLE);
4803                 hrtimer_sleeper_start_expires(&hs, mode);
4804                 if (hs.task)
4805                         io_schedule();
4806                 hrtimer_cancel(&hs.timer);
4807                 mode = HRTIMER_MODE_ABS;
4808         } while (hs.task && !signal_pending(current));
4809
4810         __set_current_state(TASK_RUNNING);
4811         destroy_hrtimer_on_stack(&hs.timer);
4812
4813         /*
4814          * If we sleep, have the caller restart the poll loop to reset the
4815          * state.  Like for the other success return cases, the caller is
4816          * responsible for checking if the IO completed.  If the IO isn't
4817          * complete, we'll get called again and will go straight to the busy
4818          * poll loop.
4819          */
4820         return true;
4821 }
4822
4823 static int blk_mq_poll_classic(struct request_queue *q, blk_qc_t cookie,
4824                                struct io_comp_batch *iob, unsigned int flags)
4825 {
4826         struct blk_mq_hw_ctx *hctx = blk_qc_to_hctx(q, cookie);
4827         long state = get_current_state();
4828         int ret;
4829
4830         do {
4831                 ret = q->mq_ops->poll(hctx, iob);
4832                 if (ret > 0) {
4833                         __set_current_state(TASK_RUNNING);
4834                         return ret;
4835                 }
4836
4837                 if (signal_pending_state(state, current))
4838                         __set_current_state(TASK_RUNNING);
4839                 if (task_is_running(current))
4840                         return 1;
4841
4842                 if (ret < 0 || (flags & BLK_POLL_ONESHOT))
4843                         break;
4844                 cpu_relax();
4845         } while (!need_resched());
4846
4847         __set_current_state(TASK_RUNNING);
4848         return 0;
4849 }
4850
4851 int blk_mq_poll(struct request_queue *q, blk_qc_t cookie, struct io_comp_batch *iob,
4852                 unsigned int flags)
4853 {
4854         if (!(flags & BLK_POLL_NOSLEEP) &&
4855             q->poll_nsec != BLK_MQ_POLL_CLASSIC) {
4856                 if (blk_mq_poll_hybrid(q, cookie))
4857                         return 1;
4858         }
4859         return blk_mq_poll_classic(q, cookie, iob, flags);
4860 }
4861
4862 unsigned int blk_mq_rq_cpu(struct request *rq)
4863 {
4864         return rq->mq_ctx->cpu;
4865 }
4866 EXPORT_SYMBOL(blk_mq_rq_cpu);
4867
4868 void blk_mq_cancel_work_sync(struct request_queue *q)
4869 {
4870         if (queue_is_mq(q)) {
4871                 struct blk_mq_hw_ctx *hctx;
4872                 unsigned long i;
4873
4874                 cancel_delayed_work_sync(&q->requeue_work);
4875
4876                 queue_for_each_hw_ctx(q, hctx, i)
4877                         cancel_delayed_work_sync(&hctx->run_work);
4878         }
4879 }
4880
4881 static int __init blk_mq_init(void)
4882 {
4883         int i;
4884
4885         for_each_possible_cpu(i)
4886                 init_llist_head(&per_cpu(blk_cpu_done, i));
4887         open_softirq(BLOCK_SOFTIRQ, blk_done_softirq);
4888
4889         cpuhp_setup_state_nocalls(CPUHP_BLOCK_SOFTIRQ_DEAD,
4890                                   "block/softirq:dead", NULL,
4891                                   blk_softirq_cpu_dead);
4892         cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD, "block/mq:dead", NULL,
4893                                 blk_mq_hctx_notify_dead);
4894         cpuhp_setup_state_multi(CPUHP_AP_BLK_MQ_ONLINE, "block/mq:online",
4895                                 blk_mq_hctx_notify_online,
4896                                 blk_mq_hctx_notify_offline);
4897         return 0;
4898 }
4899 subsys_initcall(blk_mq_init);