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(&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(&dm_mq_nr_hw_queues, 1, 32);
51}
52
53static unsigned int dm_get_blk_mq_queue_depth(void)
54{
55	return __dm_get_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(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(tio->orig, BLK_STS_OK, 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(orig);
131
132		tio->duration_jiffies = jiffies - tio->duration_jiffies;
133		dm_stats_account_io(&md->stats, rq_data_dir(orig),
134				    blk_rq_pos(orig), tio->n_sectors, true,
135				    tio->duration_jiffies, &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(clone);
164	tio->ti->type->release_clone_rq(clone, NULL);
165
166	rq_end_stats(md, 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(md->queue, 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, false);
185	__dm_mq_kick_requeue_list(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, rq);
195	if (tio->clone) {
196		blk_rq_unprep_clone(tio->clone);
197		tio->ti->type->release_clone_rq(tio->clone, NULL);
198	}
199
200	dm_mq_delay_requeue_request(rq, 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(clone) == REQ_OP_DISCARD &&
219		    !clone->q->limits.max_discard_sectors)
220			disable_discard(tio->md);
221		else if (req_op(clone) == REQ_OP_WRITE_ZEROES &&
222			 !clone->q->limits.max_write_zeroes_sectors)
223			disable_write_zeroes(tio->md);
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, 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, 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, rq);
261		blk_mq_end_request(rq, 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, 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(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(clone, rq, &tio->md->mempools->bs, gfp_mask,
326			      dm_rq_bio_constructor, 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(clone, disk_devt(dm_disk(md)),
385				     blk_rq_pos(rq));
386		ret = blk_insert_cloned_request(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(clone);
393			blk_mq_cleanup_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, 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, 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, "%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(orig);
436
437	if (unlikely(dm_stats_used(&md->stats))) {
438		struct dm_rq_target_io *tio = tio_from_request(orig);
439
440		tio->duration_jiffies = jiffies;
441		tio->n_sectors = blk_rq_sectors(orig);
442		dm_stats_account_io(&md->stats, rq_data_dir(orig),
443				    blk_rq_pos(orig), tio->n_sectors, false, 0,
444				    &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);
498		if (unlikely(!map)) {
499			dm_put_live_table(md, srcu_idx);
500			return BLK_STS_RESOURCE;
501		}
502		ti = dm_table_find_target(map, 0);
503		dm_put_live_table(md, srcu_idx);
504	}
505
506	if (ti->type->busy && ti->type->busy(ti))
507		return BLK_STS_RESOURCE;
508
509	dm_start_request(md, rq);
510
511	/* Init tio using md established in .init_request */
512	init_tio(tio, rq, md);
513
514	/*
515	 * Establish tio->ti before calling map_request().
516	 */
517	tio->ti = ti;
518
519	/* Direct call is fine since .queue_rq allows allocations */
520	if (map_request(tio) == DM_MAPIO_REQUEUE) {
521		/* Undo dm_start_request() before requeuing */
522		rq_end_stats(md, rq);
523		rq_completed(md);
524		return BLK_STS_RESOURCE;
525	}
526
527	return BLK_STS_OK;
528}
529
530static const struct blk_mq_ops dm_mq_ops = {
531	.queue_rq = dm_mq_queue_rq,
532	.complete = dm_softirq_done,
533	.init_request = dm_mq_init_request,
534};
535
536int dm_mq_init_request_queue(struct mapped_device *md, struct dm_table *t)
537{
538	struct dm_target *immutable_tgt;
539	int err;
540
541	md->tag_set = kzalloc_node(sizeof(struct blk_mq_tag_set), GFP_KERNEL, md->numa_node_id);
542	if (!md->tag_set)
543		return -ENOMEM;
544
545	md->tag_set->ops = &dm_mq_ops;
546	md->tag_set->queue_depth = dm_get_blk_mq_queue_depth();
547	md->tag_set->numa_node = md->numa_node_id;
548	md->tag_set->flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_STACKING;
549	md->tag_set->nr_hw_queues = dm_get_blk_mq_nr_hw_queues();
550	md->tag_set->driver_data = md;
551
552	md->tag_set->cmd_size = sizeof(struct dm_rq_target_io);
553	immutable_tgt = dm_table_get_immutable_target(t);
554	if (immutable_tgt && immutable_tgt->per_io_data_size) {
555		/* any target-specific per-io data is immediately after the tio */
556		md->tag_set->cmd_size += immutable_tgt->per_io_data_size;
557		md->init_tio_pdu = true;
558	}
559
560	err = blk_mq_alloc_tag_set(md->tag_set);
561	if (err)
562		goto out_kfree_tag_set;
563
564	err = blk_mq_init_allocated_queue(md->tag_set, md->queue);
565	if (err)
566		goto out_tag_set;
567	return 0;
568
569out_tag_set:
570	blk_mq_free_tag_set(md->tag_set);
571out_kfree_tag_set:
572	kfree(md->tag_set);
573	md->tag_set = NULL;
574
575	return err;
576}
577
578void dm_mq_cleanup_mapped_device(struct mapped_device *md)
579{
580	if (md->tag_set) {
581		blk_mq_free_tag_set(md->tag_set);
582		kfree(md->tag_set);
583		md->tag_set = NULL;
584	}
585}
586
587module_param(reserved_rq_based_ios, uint, 0644);
588MODULE_PARM_DESC(reserved_rq_based_ios, "Reserved IOs in request-based mempools");
589
590/* Unused, but preserved for userspace compatibility */
591static bool use_blk_mq = true;
592module_param(use_blk_mq, bool, 0644);
593MODULE_PARM_DESC(use_blk_mq, "Use block multiqueue for request-based DM devices");
594
595module_param(dm_mq_nr_hw_queues, uint, 0644);
596MODULE_PARM_DESC(dm_mq_nr_hw_queues, "Number of hardware queues for request-based dm-mq devices");
597
598module_param(dm_mq_queue_depth, uint, 0644);
599MODULE_PARM_DESC(dm_mq_queue_depth, "Queue depth for request-based dm-mq devices");
600