1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2016 Red Hat, Inc. All rights reserved.
4 *
5 * This file is released under the GPL.
6 */
7
8#include "dm-core.h"
9#include "dm-rq.h"
10
11#include <linux/blk-mq.h>
12
13#define DM_MSG_PREFIX "core-rq"
14
15/*
16 * One of these is allocated per request.
17 */
18struct dm_rq_target_io {
19 struct mapped_device *md;
20 struct dm_target *ti;
21 struct request *orig, *clone;
22 struct kthread_work work;
23 blk_status_t error;
24 union map_info info;
25 struct dm_stats_aux stats_aux;
26 unsigned long duration_jiffies;
27 unsigned int n_sectors;
28 unsigned int completed;
29};
30
31#define DM_MQ_NR_HW_QUEUES 1
32#define DM_MQ_QUEUE_DEPTH 2048
33static unsigned int dm_mq_nr_hw_queues = DM_MQ_NR_HW_QUEUES;
34static unsigned int dm_mq_queue_depth = DM_MQ_QUEUE_DEPTH;
35
36/*
37 * Request-based DM's mempools' reserved IOs set by the user.
38 */
39#define RESERVED_REQUEST_BASED_IOS 256
40static unsigned int reserved_rq_based_ios = RESERVED_REQUEST_BASED_IOS;
41
42unsigned int dm_get_reserved_rq_based_ios(void)
43{
44 return __dm_get_module_param(module_param: &reserved_rq_based_ios,
45 RESERVED_REQUEST_BASED_IOS, DM_RESERVED_MAX_IOS);
46}
47
48static unsigned int dm_get_blk_mq_nr_hw_queues(void)
49{
50 return __dm_get_module_param(module_param: &dm_mq_nr_hw_queues, def: 1, max: 32);
51}
52
53static unsigned int dm_get_blk_mq_queue_depth(void)
54{
55 return __dm_get_module_param(module_param: &dm_mq_queue_depth,
56 DM_MQ_QUEUE_DEPTH, BLK_MQ_MAX_DEPTH);
57}
58
59int dm_request_based(struct mapped_device *md)
60{
61 return queue_is_mq(q: md->queue);
62}
63
64void dm_start_queue(struct request_queue *q)
65{
66 blk_mq_unquiesce_queue(q);
67 blk_mq_kick_requeue_list(q);
68}
69
70void dm_stop_queue(struct request_queue *q)
71{
72 blk_mq_quiesce_queue(q);
73}
74
75/*
76 * Partial completion handling for request-based dm
77 */
78static void end_clone_bio(struct bio *clone)
79{
80 struct dm_rq_clone_bio_info *info =
81 container_of(clone, struct dm_rq_clone_bio_info, clone);
82 struct dm_rq_target_io *tio = info->tio;
83 unsigned int nr_bytes = info->orig->bi_iter.bi_size;
84 blk_status_t error = clone->bi_status;
85 bool is_last = !clone->bi_next;
86
87 bio_put(clone);
88
89 if (tio->error)
90 /*
91 * An error has already been detected on the request.
92 * Once error occurred, just let clone->end_io() handle
93 * the remainder.
94 */
95 return;
96 else if (error) {
97 /*
98 * Don't notice the error to the upper layer yet.
99 * The error handling decision is made by the target driver,
100 * when the request is completed.
101 */
102 tio->error = error;
103 goto exit;
104 }
105
106 /*
107 * I/O for the bio successfully completed.
108 * Notice the data completion to the upper layer.
109 */
110 tio->completed += nr_bytes;
111
112 /*
113 * Update the original request.
114 * Do not use blk_mq_end_request() here, because it may complete
115 * the original request before the clone, and break the ordering.
116 */
117 if (is_last)
118 exit:
119 blk_update_request(rq: tio->orig, BLK_STS_OK, nr_bytes: tio->completed);
120}
121
122static struct dm_rq_target_io *tio_from_request(struct request *rq)
123{
124 return blk_mq_rq_to_pdu(rq);
125}
126
127static void rq_end_stats(struct mapped_device *md, struct request *orig)
128{
129 if (unlikely(dm_stats_used(&md->stats))) {
130 struct dm_rq_target_io *tio = tio_from_request(rq: orig);
131
132 tio->duration_jiffies = jiffies - tio->duration_jiffies;
133 dm_stats_account_io(stats: &md->stats, rq_data_dir(orig),
134 bi_sector: blk_rq_pos(rq: orig), bi_sectors: tio->n_sectors, end: true,
135 start_time: tio->duration_jiffies, aux: &tio->stats_aux);
136 }
137}
138
139/*
140 * Don't touch any member of the md after calling this function because
141 * the md may be freed in dm_put() at the end of this function.
142 * Or do dm_get() before calling this function and dm_put() later.
143 */
144static void rq_completed(struct mapped_device *md)
145{
146 /*
147 * dm_put() must be at the end of this function. See the comment above
148 */
149 dm_put(md);
150}
151
152/*
153 * Complete the clone and the original request.
154 * Must be called without clone's queue lock held,
155 * see end_clone_request() for more details.
156 */
157static void dm_end_request(struct request *clone, blk_status_t error)
158{
159 struct dm_rq_target_io *tio = clone->end_io_data;
160 struct mapped_device *md = tio->md;
161 struct request *rq = tio->orig;
162
163 blk_rq_unprep_clone(rq: clone);
164 tio->ti->type->release_clone_rq(clone, NULL);
165
166 rq_end_stats(md, orig: rq);
167 blk_mq_end_request(rq, error);
168 rq_completed(md);
169}
170
171static void __dm_mq_kick_requeue_list(struct request_queue *q, unsigned long msecs)
172{
173 blk_mq_delay_kick_requeue_list(q, msecs);
174}
175
176void dm_mq_kick_requeue_list(struct mapped_device *md)
177{
178 __dm_mq_kick_requeue_list(q: md->queue, msecs: 0);
179}
180EXPORT_SYMBOL(dm_mq_kick_requeue_list);
181
182static void dm_mq_delay_requeue_request(struct request *rq, unsigned long msecs)
183{
184 blk_mq_requeue_request(rq, kick_requeue_list: false);
185 __dm_mq_kick_requeue_list(q: rq->q, msecs);
186}
187
188static void dm_requeue_original_request(struct dm_rq_target_io *tio, bool delay_requeue)
189{
190 struct mapped_device *md = tio->md;
191 struct request *rq = tio->orig;
192 unsigned long delay_ms = delay_requeue ? 100 : 0;
193
194 rq_end_stats(md, orig: rq);
195 if (tio->clone) {
196 blk_rq_unprep_clone(rq: tio->clone);
197 tio->ti->type->release_clone_rq(tio->clone, NULL);
198 }
199
200 dm_mq_delay_requeue_request(rq, msecs: delay_ms);
201 rq_completed(md);
202}
203
204static void dm_done(struct request *clone, blk_status_t error, bool mapped)
205{
206 int r = DM_ENDIO_DONE;
207 struct dm_rq_target_io *tio = clone->end_io_data;
208 dm_request_endio_fn rq_end_io = NULL;
209
210 if (tio->ti) {
211 rq_end_io = tio->ti->type->rq_end_io;
212
213 if (mapped && rq_end_io)
214 r = rq_end_io(tio->ti, clone, error, &tio->info);
215 }
216
217 if (unlikely(error == BLK_STS_TARGET)) {
218 if (req_op(req: clone) == REQ_OP_DISCARD &&
219 !clone->q->limits.max_discard_sectors)
220 blk_queue_disable_discard(q: tio->md->queue);
221 else if (req_op(req: clone) == REQ_OP_WRITE_ZEROES &&
222 !clone->q->limits.max_write_zeroes_sectors)
223 blk_queue_disable_write_zeroes(q: tio->md->queue);
224 }
225
226 switch (r) {
227 case DM_ENDIO_DONE:
228 /* The target wants to complete the I/O */
229 dm_end_request(clone, error);
230 break;
231 case DM_ENDIO_INCOMPLETE:
232 /* The target will handle the I/O */
233 return;
234 case DM_ENDIO_REQUEUE:
235 /* The target wants to requeue the I/O */
236 dm_requeue_original_request(tio, delay_requeue: false);
237 break;
238 case DM_ENDIO_DELAY_REQUEUE:
239 /* The target wants to requeue the I/O after a delay */
240 dm_requeue_original_request(tio, delay_requeue: true);
241 break;
242 default:
243 DMCRIT("unimplemented target endio return value: %d", r);
244 BUG();
245 }
246}
247
248/*
249 * Request completion handler for request-based dm
250 */
251static void dm_softirq_done(struct request *rq)
252{
253 bool mapped = true;
254 struct dm_rq_target_io *tio = tio_from_request(rq);
255 struct request *clone = tio->clone;
256
257 if (!clone) {
258 struct mapped_device *md = tio->md;
259
260 rq_end_stats(md, orig: rq);
261 blk_mq_end_request(rq, error: tio->error);
262 rq_completed(md);
263 return;
264 }
265
266 if (rq->rq_flags & RQF_FAILED)
267 mapped = false;
268
269 dm_done(clone, error: tio->error, mapped);
270}
271
272/*
273 * Complete the clone and the original request with the error status
274 * through softirq context.
275 */
276static void dm_complete_request(struct request *rq, blk_status_t error)
277{
278 struct dm_rq_target_io *tio = tio_from_request(rq);
279
280 tio->error = error;
281 if (likely(!blk_should_fake_timeout(rq->q)))
282 blk_mq_complete_request(rq);
283}
284
285/*
286 * Complete the not-mapped clone and the original request with the error status
287 * through softirq context.
288 * Target's rq_end_io() function isn't called.
289 * This may be used when the target's clone_and_map_rq() function fails.
290 */
291static void dm_kill_unmapped_request(struct request *rq, blk_status_t error)
292{
293 rq->rq_flags |= RQF_FAILED;
294 dm_complete_request(rq, error);
295}
296
297static enum rq_end_io_ret end_clone_request(struct request *clone,
298 blk_status_t error)
299{
300 struct dm_rq_target_io *tio = clone->end_io_data;
301
302 dm_complete_request(rq: tio->orig, error);
303 return RQ_END_IO_NONE;
304}
305
306static int dm_rq_bio_constructor(struct bio *bio, struct bio *bio_orig,
307 void *data)
308{
309 struct dm_rq_target_io *tio = data;
310 struct dm_rq_clone_bio_info *info =
311 container_of(bio, struct dm_rq_clone_bio_info, clone);
312
313 info->orig = bio_orig;
314 info->tio = tio;
315 bio->bi_end_io = end_clone_bio;
316
317 return 0;
318}
319
320static int setup_clone(struct request *clone, struct request *rq,
321 struct dm_rq_target_io *tio, gfp_t gfp_mask)
322{
323 int r;
324
325 r = blk_rq_prep_clone(rq: clone, rq_src: rq, bs: &tio->md->mempools->bs, gfp_mask,
326 bio_ctr: dm_rq_bio_constructor, data: tio);
327 if (r)
328 return r;
329
330 clone->end_io = end_clone_request;
331 clone->end_io_data = tio;
332
333 tio->clone = clone;
334
335 return 0;
336}
337
338static void init_tio(struct dm_rq_target_io *tio, struct request *rq,
339 struct mapped_device *md)
340{
341 tio->md = md;
342 tio->ti = NULL;
343 tio->clone = NULL;
344 tio->orig = rq;
345 tio->error = 0;
346 tio->completed = 0;
347 /*
348 * Avoid initializing info for blk-mq; it passes
349 * target-specific data through info.ptr
350 * (see: dm_mq_init_request)
351 */
352 if (!md->init_tio_pdu)
353 memset(&tio->info, 0, sizeof(tio->info));
354}
355
356/*
357 * Returns:
358 * DM_MAPIO_* : the request has been processed as indicated
359 * DM_MAPIO_REQUEUE : the original request needs to be immediately requeued
360 * < 0 : the request was completed due to failure
361 */
362static int map_request(struct dm_rq_target_io *tio)
363{
364 int r;
365 struct dm_target *ti = tio->ti;
366 struct mapped_device *md = tio->md;
367 struct request *rq = tio->orig;
368 struct request *clone = NULL;
369 blk_status_t ret;
370
371 r = ti->type->clone_and_map_rq(ti, rq, &tio->info, &clone);
372 switch (r) {
373 case DM_MAPIO_SUBMITTED:
374 /* The target has taken the I/O to submit by itself later */
375 break;
376 case DM_MAPIO_REMAPPED:
377 if (setup_clone(clone, rq, tio, GFP_ATOMIC)) {
378 /* -ENOMEM */
379 ti->type->release_clone_rq(clone, &tio->info);
380 return DM_MAPIO_REQUEUE;
381 }
382
383 /* The target has remapped the I/O so dispatch it */
384 trace_block_rq_remap(rq: clone, dev: disk_devt(disk: dm_disk(md)),
385 from: blk_rq_pos(rq));
386 ret = blk_insert_cloned_request(rq: clone);
387 switch (ret) {
388 case BLK_STS_OK:
389 break;
390 case BLK_STS_RESOURCE:
391 case BLK_STS_DEV_RESOURCE:
392 blk_rq_unprep_clone(rq: clone);
393 blk_mq_cleanup_rq(rq: clone);
394 tio->ti->type->release_clone_rq(clone, &tio->info);
395 tio->clone = NULL;
396 return DM_MAPIO_REQUEUE;
397 default:
398 /* must complete clone in terms of original request */
399 dm_complete_request(rq, error: ret);
400 }
401 break;
402 case DM_MAPIO_REQUEUE:
403 /* The target wants to requeue the I/O */
404 break;
405 case DM_MAPIO_DELAY_REQUEUE:
406 /* The target wants to requeue the I/O after a delay */
407 dm_requeue_original_request(tio, delay_requeue: true);
408 break;
409 case DM_MAPIO_KILL:
410 /* The target wants to complete the I/O */
411 dm_kill_unmapped_request(rq, BLK_STS_IOERR);
412 break;
413 default:
414 DMCRIT("unimplemented target map return value: %d", r);
415 BUG();
416 }
417
418 return r;
419}
420
421/* DEPRECATED: previously used for request-based merge heuristic in dm_request_fn() */
422ssize_t dm_attr_rq_based_seq_io_merge_deadline_show(struct mapped_device *md, char *buf)
423{
424 return sprintf(buf, fmt: "%u\n", 0);
425}
426
427ssize_t dm_attr_rq_based_seq_io_merge_deadline_store(struct mapped_device *md,
428 const char *buf, size_t count)
429{
430 return count;
431}
432
433static void dm_start_request(struct mapped_device *md, struct request *orig)
434{
435 blk_mq_start_request(rq: orig);
436
437 if (unlikely(dm_stats_used(&md->stats))) {
438 struct dm_rq_target_io *tio = tio_from_request(rq: orig);
439
440 tio->duration_jiffies = jiffies;
441 tio->n_sectors = blk_rq_sectors(rq: orig);
442 dm_stats_account_io(stats: &md->stats, rq_data_dir(orig),
443 bi_sector: blk_rq_pos(rq: orig), bi_sectors: tio->n_sectors, end: false, start_time: 0,
444 aux: &tio->stats_aux);
445 }
446
447 /*
448 * Hold the md reference here for the in-flight I/O.
449 * We can't rely on the reference count by device opener,
450 * because the device may be closed during the request completion
451 * when all bios are completed.
452 * See the comment in rq_completed() too.
453 */
454 dm_get(md);
455}
456
457static int dm_mq_init_request(struct blk_mq_tag_set *set, struct request *rq,
458 unsigned int hctx_idx, unsigned int numa_node)
459{
460 struct mapped_device *md = set->driver_data;
461 struct dm_rq_target_io *tio = blk_mq_rq_to_pdu(rq);
462
463 /*
464 * Must initialize md member of tio, otherwise it won't
465 * be available in dm_mq_queue_rq.
466 */
467 tio->md = md;
468
469 if (md->init_tio_pdu) {
470 /* target-specific per-io data is immediately after the tio */
471 tio->info.ptr = tio + 1;
472 }
473
474 return 0;
475}
476
477static blk_status_t dm_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
478 const struct blk_mq_queue_data *bd)
479{
480 struct request *rq = bd->rq;
481 struct dm_rq_target_io *tio = blk_mq_rq_to_pdu(rq);
482 struct mapped_device *md = tio->md;
483 struct dm_target *ti = md->immutable_target;
484
485 /*
486 * blk-mq's unquiesce may come from outside events, such as
487 * elevator switch, updating nr_requests or others, and request may
488 * come during suspend, so simply ask for blk-mq to requeue it.
489 */
490 if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)))
491 return BLK_STS_RESOURCE;
492
493 if (unlikely(!ti)) {
494 int srcu_idx;
495 struct dm_table *map;
496
497 map = dm_get_live_table(md, srcu_idx: &srcu_idx);
498 if (unlikely(!map)) {
499 DMERR_LIMIT("%s: mapping table unavailable, erroring io",
500 dm_device_name(md));
501 dm_put_live_table(md, srcu_idx);
502 return BLK_STS_IOERR;
503 }
504 ti = dm_table_find_target(t: map, sector: 0);
505 dm_put_live_table(md, srcu_idx);
506 }
507
508 if (ti->type->busy && ti->type->busy(ti))
509 return BLK_STS_RESOURCE;
510
511 dm_start_request(md, orig: rq);
512
513 /* Init tio using md established in .init_request */
514 init_tio(tio, rq, md);
515
516 /*
517 * Establish tio->ti before calling map_request().
518 */
519 tio->ti = ti;
520
521 /* Direct call is fine since .queue_rq allows allocations */
522 if (map_request(tio) == DM_MAPIO_REQUEUE) {
523 /* Undo dm_start_request() before requeuing */
524 rq_end_stats(md, orig: rq);
525 rq_completed(md);
526 return BLK_STS_RESOURCE;
527 }
528
529 return BLK_STS_OK;
530}
531
532static const struct blk_mq_ops dm_mq_ops = {
533 .queue_rq = dm_mq_queue_rq,
534 .complete = dm_softirq_done,
535 .init_request = dm_mq_init_request,
536};
537
538int dm_mq_init_request_queue(struct mapped_device *md, struct dm_table *t)
539{
540 struct dm_target *immutable_tgt;
541 int err;
542
543 md->tag_set = kzalloc_node(sizeof(struct blk_mq_tag_set), GFP_KERNEL, md->numa_node_id);
544 if (!md->tag_set)
545 return -ENOMEM;
546
547 md->tag_set->ops = &dm_mq_ops;
548 md->tag_set->queue_depth = dm_get_blk_mq_queue_depth();
549 md->tag_set->numa_node = md->numa_node_id;
550 md->tag_set->flags = BLK_MQ_F_STACKING;
551 md->tag_set->nr_hw_queues = dm_get_blk_mq_nr_hw_queues();
552 md->tag_set->driver_data = md;
553
554 md->tag_set->cmd_size = sizeof(struct dm_rq_target_io);
555 immutable_tgt = dm_table_get_immutable_target(t);
556 if (immutable_tgt && immutable_tgt->per_io_data_size) {
557 /* any target-specific per-io data is immediately after the tio */
558 md->tag_set->cmd_size += immutable_tgt->per_io_data_size;
559 md->init_tio_pdu = true;
560 }
561
562 err = blk_mq_alloc_tag_set(set: md->tag_set);
563 if (err)
564 goto out_kfree_tag_set;
565
566 err = blk_mq_init_allocated_queue(set: md->tag_set, q: md->queue);
567 if (err)
568 goto out_tag_set;
569 return 0;
570
571out_tag_set:
572 blk_mq_free_tag_set(set: md->tag_set);
573out_kfree_tag_set:
574 kfree(objp: md->tag_set);
575 md->tag_set = NULL;
576
577 return err;
578}
579
580void dm_mq_cleanup_mapped_device(struct mapped_device *md)
581{
582 if (md->tag_set) {
583 blk_mq_free_tag_set(set: md->tag_set);
584 kfree(objp: md->tag_set);
585 md->tag_set = NULL;
586 }
587}
588
589module_param(reserved_rq_based_ios, uint, 0644);
590MODULE_PARM_DESC(reserved_rq_based_ios, "Reserved IOs in request-based mempools");
591
592/* Unused, but preserved for userspace compatibility */
593static bool use_blk_mq = true;
594module_param(use_blk_mq, bool, 0644);
595MODULE_PARM_DESC(use_blk_mq, "Use block multiqueue for request-based DM devices");
596
597module_param(dm_mq_nr_hw_queues, uint, 0644);
598MODULE_PARM_DESC(dm_mq_nr_hw_queues, "Number of hardware queues for request-based dm-mq devices");
599
600module_param(dm_mq_queue_depth, uint, 0644);
601MODULE_PARM_DESC(dm_mq_queue_depth, "Queue depth for request-based dm-mq devices");
602

source code of linux/drivers/md/dm-rq.c