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1 /*
2 * Copyright (C) 2003 Sistina Software Limited.
3 * Copyright (C) 2004-2005 Red Hat, Inc. All rights reserved.
4 *
5 * This file is released under the GPL.
6 */
7
8 #include <linux/device-mapper.h>
9
10 #include "dm-rq.h"
11 #include "dm-bio-record.h"
12 #include "dm-path-selector.h"
13 #include "dm-uevent.h"
14
15 #include <linux/blkdev.h>
16 #include <linux/ctype.h>
17 #include <linux/init.h>
18 #include <linux/mempool.h>
19 #include <linux/module.h>
20 #include <linux/pagemap.h>
21 #include <linux/slab.h>
22 #include <linux/time.h>
23 #include <linux/timer.h>
24 #include <linux/workqueue.h>
25 #include <linux/delay.h>
26 #include <scsi/scsi_dh.h>
27 #include <linux/atomic.h>
28 #include <linux/blk-mq.h>
29
30 #define DM_MSG_PREFIX "multipath"
31 #define DM_PG_INIT_DELAY_MSECS 2000
32 #define DM_PG_INIT_DELAY_DEFAULT ((unsigned) -1)
33 #define QUEUE_IF_NO_PATH_TIMEOUT_DEFAULT 0
34
35 static unsigned long queue_if_no_path_timeout_secs = QUEUE_IF_NO_PATH_TIMEOUT_DEFAULT;
36
37 /* Path properties */
38 struct pgpath {
39 struct list_head list;
40
41 struct priority_group *pg; /* Owning PG */
42 unsigned fail_count; /* Cumulative failure count */
43
44 struct dm_path path;
45 struct delayed_work activate_path;
46
47 bool is_active:1; /* Path status */
48 };
49
50 #define path_to_pgpath(__pgp) container_of((__pgp), struct pgpath, path)
51
52 /*
53 * Paths are grouped into Priority Groups and numbered from 1 upwards.
54 * Each has a path selector which controls which path gets used.
55 */
56 struct priority_group {
57 struct list_head list;
58
59 struct multipath *m; /* Owning multipath instance */
60 struct path_selector ps;
61
62 unsigned pg_num; /* Reference number */
63 unsigned nr_pgpaths; /* Number of paths in PG */
64 struct list_head pgpaths;
65
66 bool bypassed:1; /* Temporarily bypass this PG? */
67 };
68
69 /* Multipath context */
70 struct multipath {
71 unsigned long flags; /* Multipath state flags */
72
73 spinlock_t lock;
74 enum dm_queue_mode queue_mode;
75
76 struct pgpath *current_pgpath;
77 struct priority_group *current_pg;
78 struct priority_group *next_pg; /* Switch to this PG if set */
79
80 atomic_t nr_valid_paths; /* Total number of usable paths */
81 unsigned nr_priority_groups;
82 struct list_head priority_groups;
83
84 const char *hw_handler_name;
85 char *hw_handler_params;
86 wait_queue_head_t pg_init_wait; /* Wait for pg_init completion */
87 unsigned pg_init_retries; /* Number of times to retry pg_init */
88 unsigned pg_init_delay_msecs; /* Number of msecs before pg_init retry */
89 atomic_t pg_init_in_progress; /* Only one pg_init allowed at once */
90 atomic_t pg_init_count; /* Number of times pg_init called */
91
92 struct mutex work_mutex;
93 struct work_struct trigger_event;
94 struct dm_target *ti;
95
96 struct work_struct process_queued_bios;
97 struct bio_list queued_bios;
98
99 struct timer_list nopath_timer; /* Timeout for queue_if_no_path */
100 };
101
102 /*
103 * Context information attached to each io we process.
104 */
105 struct dm_mpath_io {
106 struct pgpath *pgpath;
107 size_t nr_bytes;
108 };
109
110 typedef int (*action_fn) (struct pgpath *pgpath);
111
112 static struct workqueue_struct *kmultipathd, *kmpath_handlerd;
113 static void trigger_event(struct work_struct *work);
114 static void activate_or_offline_path(struct pgpath *pgpath);
115 static void activate_path_work(struct work_struct *work);
116 static void process_queued_bios(struct work_struct *work);
117 static void queue_if_no_path_timeout_work(struct timer_list *t);
118
119 /*-----------------------------------------------
120 * Multipath state flags.
121 *-----------------------------------------------*/
122
123 #define MPATHF_QUEUE_IO 0 /* Must we queue all I/O? */
124 #define MPATHF_QUEUE_IF_NO_PATH 1 /* Queue I/O if last path fails? */
125 #define MPATHF_SAVED_QUEUE_IF_NO_PATH 2 /* Saved state during suspension */
126 #define MPATHF_RETAIN_ATTACHED_HW_HANDLER 3 /* If there's already a hw_handler present, don't change it. */
127 #define MPATHF_PG_INIT_DISABLED 4 /* pg_init is not currently allowed */
128 #define MPATHF_PG_INIT_REQUIRED 5 /* pg_init needs calling? */
129 #define MPATHF_PG_INIT_DELAY_RETRY 6 /* Delay pg_init retry? */
130
131 static bool mpath_double_check_test_bit(int MPATHF_bit, struct multipath *m)
132 {
133 bool r = test_bit(MPATHF_bit, &m->flags);
134
135 if (r) {
136 unsigned long flags;
137 spin_lock_irqsave(&m->lock, flags);
138 r = test_bit(MPATHF_bit, &m->flags);
139 spin_unlock_irqrestore(&m->lock, flags);
140 }
141
142 return r;
143 }
144
145 /*-----------------------------------------------
146 * Allocation routines
147 *-----------------------------------------------*/
148
149 static struct pgpath *alloc_pgpath(void)
150 {
151 struct pgpath *pgpath = kzalloc(sizeof(*pgpath), GFP_KERNEL);
152
153 if (!pgpath)
154 return NULL;
155
156 pgpath->is_active = true;
157
158 return pgpath;
159 }
160
161 static void free_pgpath(struct pgpath *pgpath)
162 {
163 kfree(pgpath);
164 }
165
166 static struct priority_group *alloc_priority_group(void)
167 {
168 struct priority_group *pg;
169
170 pg = kzalloc(sizeof(*pg), GFP_KERNEL);
171
172 if (pg)
173 INIT_LIST_HEAD(&pg->pgpaths);
174
175 return pg;
176 }
177
178 static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti)
179 {
180 struct pgpath *pgpath, *tmp;
181
182 list_for_each_entry_safe(pgpath, tmp, pgpaths, list) {
183 list_del(&pgpath->list);
184 dm_put_device(ti, pgpath->path.dev);
185 free_pgpath(pgpath);
186 }
187 }
188
189 static void free_priority_group(struct priority_group *pg,
190 struct dm_target *ti)
191 {
192 struct path_selector *ps = &pg->ps;
193
194 if (ps->type) {
195 ps->type->destroy(ps);
196 dm_put_path_selector(ps->type);
197 }
198
199 free_pgpaths(&pg->pgpaths, ti);
200 kfree(pg);
201 }
202
203 static struct multipath *alloc_multipath(struct dm_target *ti)
204 {
205 struct multipath *m;
206
207 m = kzalloc(sizeof(*m), GFP_KERNEL);
208 if (m) {
209 INIT_LIST_HEAD(&m->priority_groups);
210 spin_lock_init(&m->lock);
211 atomic_set(&m->nr_valid_paths, 0);
212 INIT_WORK(&m->trigger_event, trigger_event);
213 mutex_init(&m->work_mutex);
214
215 m->queue_mode = DM_TYPE_NONE;
216
217 m->ti = ti;
218 ti->private = m;
219
220 timer_setup(&m->nopath_timer, queue_if_no_path_timeout_work, 0);
221 }
222
223 return m;
224 }
225
226 static int alloc_multipath_stage2(struct dm_target *ti, struct multipath *m)
227 {
228 if (m->queue_mode == DM_TYPE_NONE) {
229 m->queue_mode = DM_TYPE_REQUEST_BASED;
230 } else if (m->queue_mode == DM_TYPE_BIO_BASED) {
231 INIT_WORK(&m->process_queued_bios, process_queued_bios);
232 /*
233 * bio-based doesn't support any direct scsi_dh management;
234 * it just discovers if a scsi_dh is attached.
235 */
236 set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags);
237 }
238
239 dm_table_set_type(ti->table, m->queue_mode);
240
241 /*
242 * Init fields that are only used when a scsi_dh is attached
243 * - must do this unconditionally (really doesn't hurt non-SCSI uses)
244 */
245 set_bit(MPATHF_QUEUE_IO, &m->flags);
246 atomic_set(&m->pg_init_in_progress, 0);
247 atomic_set(&m->pg_init_count, 0);
248 m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT;
249 init_waitqueue_head(&m->pg_init_wait);
250
251 return 0;
252 }
253
254 static void free_multipath(struct multipath *m)
255 {
256 struct priority_group *pg, *tmp;
257
258 list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) {
259 list_del(&pg->list);
260 free_priority_group(pg, m->ti);
261 }
262
263 kfree(m->hw_handler_name);
264 kfree(m->hw_handler_params);
265 mutex_destroy(&m->work_mutex);
266 kfree(m);
267 }
268
269 static struct dm_mpath_io *get_mpio(union map_info *info)
270 {
271 return info->ptr;
272 }
273
274 static size_t multipath_per_bio_data_size(void)
275 {
276 return sizeof(struct dm_mpath_io) + sizeof(struct dm_bio_details);
277 }
278
279 static struct dm_mpath_io *get_mpio_from_bio(struct bio *bio)
280 {
281 return dm_per_bio_data(bio, multipath_per_bio_data_size());
282 }
283
284 static struct dm_bio_details *get_bio_details_from_mpio(struct dm_mpath_io *mpio)
285 {
286 /* dm_bio_details is immediately after the dm_mpath_io in bio's per-bio-data */
287 void *bio_details = mpio + 1;
288 return bio_details;
289 }
290
291 static void multipath_init_per_bio_data(struct bio *bio, struct dm_mpath_io **mpio_p)
292 {
293 struct dm_mpath_io *mpio = get_mpio_from_bio(bio);
294 struct dm_bio_details *bio_details = get_bio_details_from_mpio(mpio);
295
296 mpio->nr_bytes = bio->bi_iter.bi_size;
297 mpio->pgpath = NULL;
298 *mpio_p = mpio;
299
300 dm_bio_record(bio_details, bio);
301 }
302
303 /*-----------------------------------------------
304 * Path selection
305 *-----------------------------------------------*/
306
307 static int __pg_init_all_paths(struct multipath *m)
308 {
309 struct pgpath *pgpath;
310 unsigned long pg_init_delay = 0;
311
312 lockdep_assert_held(&m->lock);
313
314 if (atomic_read(&m->pg_init_in_progress) || test_bit(MPATHF_PG_INIT_DISABLED, &m->flags))
315 return 0;
316
317 atomic_inc(&m->pg_init_count);
318 clear_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
319
320 /* Check here to reset pg_init_required */
321 if (!m->current_pg)
322 return 0;
323
324 if (test_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags))
325 pg_init_delay = msecs_to_jiffies(m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT ?
326 m->pg_init_delay_msecs : DM_PG_INIT_DELAY_MSECS);
327 list_for_each_entry(pgpath, &m->current_pg->pgpaths, list) {
328 /* Skip failed paths */
329 if (!pgpath->is_active)
330 continue;
331 if (queue_delayed_work(kmpath_handlerd, &pgpath->activate_path,
332 pg_init_delay))
333 atomic_inc(&m->pg_init_in_progress);
334 }
335 return atomic_read(&m->pg_init_in_progress);
336 }
337
338 static int pg_init_all_paths(struct multipath *m)
339 {
340 int ret;
341 unsigned long flags;
342
343 spin_lock_irqsave(&m->lock, flags);
344 ret = __pg_init_all_paths(m);
345 spin_unlock_irqrestore(&m->lock, flags);
346
347 return ret;
348 }
349
350 static void __switch_pg(struct multipath *m, struct priority_group *pg)
351 {
352 lockdep_assert_held(&m->lock);
353
354 m->current_pg = pg;
355
356 /* Must we initialise the PG first, and queue I/O till it's ready? */
357 if (m->hw_handler_name) {
358 set_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
359 set_bit(MPATHF_QUEUE_IO, &m->flags);
360 } else {
361 clear_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
362 clear_bit(MPATHF_QUEUE_IO, &m->flags);
363 }
364
365 atomic_set(&m->pg_init_count, 0);
366 }
367
368 static struct pgpath *choose_path_in_pg(struct multipath *m,
369 struct priority_group *pg,
370 size_t nr_bytes)
371 {
372 unsigned long flags;
373 struct dm_path *path;
374 struct pgpath *pgpath;
375
376 path = pg->ps.type->select_path(&pg->ps, nr_bytes);
377 if (!path)
378 return ERR_PTR(-ENXIO);
379
380 pgpath = path_to_pgpath(path);
381
382 if (unlikely(READ_ONCE(m->current_pg) != pg)) {
383 /* Only update current_pgpath if pg changed */
384 spin_lock_irqsave(&m->lock, flags);
385 m->current_pgpath = pgpath;
386 __switch_pg(m, pg);
387 spin_unlock_irqrestore(&m->lock, flags);
388 }
389
390 return pgpath;
391 }
392
393 static struct pgpath *choose_pgpath(struct multipath *m, size_t nr_bytes)
394 {
395 unsigned long flags;
396 struct priority_group *pg;
397 struct pgpath *pgpath;
398 unsigned bypassed = 1;
399
400 if (!atomic_read(&m->nr_valid_paths)) {
401 spin_lock_irqsave(&m->lock, flags);
402 clear_bit(MPATHF_QUEUE_IO, &m->flags);
403 spin_unlock_irqrestore(&m->lock, flags);
404 goto failed;
405 }
406
407 /* Were we instructed to switch PG? */
408 if (READ_ONCE(m->next_pg)) {
409 spin_lock_irqsave(&m->lock, flags);
410 pg = m->next_pg;
411 if (!pg) {
412 spin_unlock_irqrestore(&m->lock, flags);
413 goto check_current_pg;
414 }
415 m->next_pg = NULL;
416 spin_unlock_irqrestore(&m->lock, flags);
417 pgpath = choose_path_in_pg(m, pg, nr_bytes);
418 if (!IS_ERR_OR_NULL(pgpath))
419 return pgpath;
420 }
421
422 /* Don't change PG until it has no remaining paths */
423 check_current_pg:
424 pg = READ_ONCE(m->current_pg);
425 if (pg) {
426 pgpath = choose_path_in_pg(m, pg, nr_bytes);
427 if (!IS_ERR_OR_NULL(pgpath))
428 return pgpath;
429 }
430
431 /*
432 * Loop through priority groups until we find a valid path.
433 * First time we skip PGs marked 'bypassed'.
434 * Second time we only try the ones we skipped, but set
435 * pg_init_delay_retry so we do not hammer controllers.
436 */
437 do {
438 list_for_each_entry(pg, &m->priority_groups, list) {
439 if (pg->bypassed == !!bypassed)
440 continue;
441 pgpath = choose_path_in_pg(m, pg, nr_bytes);
442 if (!IS_ERR_OR_NULL(pgpath)) {
443 if (!bypassed) {
444 spin_lock_irqsave(&m->lock, flags);
445 set_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
446 spin_unlock_irqrestore(&m->lock, flags);
447 }
448 return pgpath;
449 }
450 }
451 } while (bypassed--);
452
453 failed:
454 spin_lock_irqsave(&m->lock, flags);
455 m->current_pgpath = NULL;
456 m->current_pg = NULL;
457 spin_unlock_irqrestore(&m->lock, flags);
458
459 return NULL;
460 }
461
462 /*
463 * dm_report_EIO() is a macro instead of a function to make pr_debug_ratelimited()
464 * report the function name and line number of the function from which
465 * it has been invoked.
466 */
467 #define dm_report_EIO(m) \
468 do { \
469 DMDEBUG_LIMIT("%s: returning EIO; QIFNP = %d; SQIFNP = %d; DNFS = %d", \
470 dm_table_device_name((m)->ti->table), \
471 test_bit(MPATHF_QUEUE_IF_NO_PATH, &(m)->flags), \
472 test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &(m)->flags), \
473 dm_noflush_suspending((m)->ti)); \
474 } while (0)
475
476 /*
477 * Check whether bios must be queued in the device-mapper core rather
478 * than here in the target.
479 */
480 static bool __must_push_back(struct multipath *m)
481 {
482 return dm_noflush_suspending(m->ti);
483 }
484
485 static bool must_push_back_rq(struct multipath *m)
486 {
487 unsigned long flags;
488 bool ret;
489
490 spin_lock_irqsave(&m->lock, flags);
491 ret = (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) || __must_push_back(m));
492 spin_unlock_irqrestore(&m->lock, flags);
493
494 return ret;
495 }
496
497 /*
498 * Map cloned requests (request-based multipath)
499 */
500 static int multipath_clone_and_map(struct dm_target *ti, struct request *rq,
501 union map_info *map_context,
502 struct request **__clone)
503 {
504 struct multipath *m = ti->private;
505 size_t nr_bytes = blk_rq_bytes(rq);
506 struct pgpath *pgpath;
507 struct block_device *bdev;
508 struct dm_mpath_io *mpio = get_mpio(map_context);
509 struct request_queue *q;
510 struct request *clone;
511
512 /* Do we need to select a new pgpath? */
513 pgpath = READ_ONCE(m->current_pgpath);
514 if (!pgpath || !mpath_double_check_test_bit(MPATHF_QUEUE_IO, m))
515 pgpath = choose_pgpath(m, nr_bytes);
516
517 if (!pgpath) {
518 if (must_push_back_rq(m))
519 return DM_MAPIO_DELAY_REQUEUE;
520 dm_report_EIO(m); /* Failed */
521 return DM_MAPIO_KILL;
522 } else if (mpath_double_check_test_bit(MPATHF_QUEUE_IO, m) ||
523 mpath_double_check_test_bit(MPATHF_PG_INIT_REQUIRED, m)) {
524 pg_init_all_paths(m);
525 return DM_MAPIO_DELAY_REQUEUE;
526 }
527
528 mpio->pgpath = pgpath;
529 mpio->nr_bytes = nr_bytes;
530
531 bdev = pgpath->path.dev->bdev;
532 q = bdev_get_queue(bdev);
533 clone = blk_get_request(q, rq->cmd_flags | REQ_NOMERGE,
534 BLK_MQ_REQ_NOWAIT);
535 if (IS_ERR(clone)) {
536 /* EBUSY, ENODEV or EWOULDBLOCK: requeue */
537 if (blk_queue_dying(q)) {
538 atomic_inc(&m->pg_init_in_progress);
539 activate_or_offline_path(pgpath);
540 return DM_MAPIO_DELAY_REQUEUE;
541 }
542
543 /*
544 * blk-mq's SCHED_RESTART can cover this requeue, so we
545 * needn't deal with it by DELAY_REQUEUE. More importantly,
546 * we have to return DM_MAPIO_REQUEUE so that blk-mq can
547 * get the queue busy feedback (via BLK_STS_RESOURCE),
548 * otherwise I/O merging can suffer.
549 */
550 return DM_MAPIO_REQUEUE;
551 }
552 clone->bio = clone->biotail = NULL;
553 clone->rq_disk = bdev->bd_disk;
554 clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
555 *__clone = clone;
556
557 if (pgpath->pg->ps.type->start_io)
558 pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
559 &pgpath->path,
560 nr_bytes);
561 return DM_MAPIO_REMAPPED;
562 }
563
564 static void multipath_release_clone(struct request *clone,
565 union map_info *map_context)
566 {
567 if (unlikely(map_context)) {
568 /*
569 * non-NULL map_context means caller is still map
570 * method; must undo multipath_clone_and_map()
571 */
572 struct dm_mpath_io *mpio = get_mpio(map_context);
573 struct pgpath *pgpath = mpio->pgpath;
574
575 if (pgpath && pgpath->pg->ps.type->end_io)
576 pgpath->pg->ps.type->end_io(&pgpath->pg->ps,
577 &pgpath->path,
578 mpio->nr_bytes,
579 clone->io_start_time_ns);
580 }
581
582 blk_put_request(clone);
583 }
584
585 /*
586 * Map cloned bios (bio-based multipath)
587 */
588
589 static void __multipath_queue_bio(struct multipath *m, struct bio *bio)
590 {
591 /* Queue for the daemon to resubmit */
592 bio_list_add(&m->queued_bios, bio);
593 if (!test_bit(MPATHF_QUEUE_IO, &m->flags))
594 queue_work(kmultipathd, &m->process_queued_bios);
595 }
596
597 static void multipath_queue_bio(struct multipath *m, struct bio *bio)
598 {
599 unsigned long flags;
600
601 spin_lock_irqsave(&m->lock, flags);
602 __multipath_queue_bio(m, bio);
603 spin_unlock_irqrestore(&m->lock, flags);
604 }
605
606 static struct pgpath *__map_bio(struct multipath *m, struct bio *bio)
607 {
608 struct pgpath *pgpath;
609 unsigned long flags;
610
611 /* Do we need to select a new pgpath? */
612 pgpath = READ_ONCE(m->current_pgpath);
613 if (!pgpath || !mpath_double_check_test_bit(MPATHF_QUEUE_IO, m))
614 pgpath = choose_pgpath(m, bio->bi_iter.bi_size);
615
616 if (!pgpath) {
617 spin_lock_irqsave(&m->lock, flags);
618 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
619 __multipath_queue_bio(m, bio);
620 pgpath = ERR_PTR(-EAGAIN);
621 }
622 spin_unlock_irqrestore(&m->lock, flags);
623
624 } else if (mpath_double_check_test_bit(MPATHF_QUEUE_IO, m) ||
625 mpath_double_check_test_bit(MPATHF_PG_INIT_REQUIRED, m)) {
626 multipath_queue_bio(m, bio);
627 pg_init_all_paths(m);
628 return ERR_PTR(-EAGAIN);
629 }
630
631 return pgpath;
632 }
633
634 static int __multipath_map_bio(struct multipath *m, struct bio *bio,
635 struct dm_mpath_io *mpio)
636 {
637 struct pgpath *pgpath = __map_bio(m, bio);
638
639 if (IS_ERR(pgpath))
640 return DM_MAPIO_SUBMITTED;
641
642 if (!pgpath) {
643 if (__must_push_back(m))
644 return DM_MAPIO_REQUEUE;
645 dm_report_EIO(m);
646 return DM_MAPIO_KILL;
647 }
648
649 mpio->pgpath = pgpath;
650
651 bio->bi_status = 0;
652 bio_set_dev(bio, pgpath->path.dev->bdev);
653 bio->bi_opf |= REQ_FAILFAST_TRANSPORT;
654
655 if (pgpath->pg->ps.type->start_io)
656 pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
657 &pgpath->path,
658 mpio->nr_bytes);
659 return DM_MAPIO_REMAPPED;
660 }
661
662 static int multipath_map_bio(struct dm_target *ti, struct bio *bio)
663 {
664 struct multipath *m = ti->private;
665 struct dm_mpath_io *mpio = NULL;
666
667 multipath_init_per_bio_data(bio, &mpio);
668 return __multipath_map_bio(m, bio, mpio);
669 }
670
671 static void process_queued_io_list(struct multipath *m)
672 {
673 if (m->queue_mode == DM_TYPE_REQUEST_BASED)
674 dm_mq_kick_requeue_list(dm_table_get_md(m->ti->table));
675 else if (m->queue_mode == DM_TYPE_BIO_BASED)
676 queue_work(kmultipathd, &m->process_queued_bios);
677 }
678
679 static void process_queued_bios(struct work_struct *work)
680 {
681 int r;
682 unsigned long flags;
683 struct bio *bio;
684 struct bio_list bios;
685 struct blk_plug plug;
686 struct multipath *m =
687 container_of(work, struct multipath, process_queued_bios);
688
689 bio_list_init(&bios);
690
691 spin_lock_irqsave(&m->lock, flags);
692
693 if (bio_list_empty(&m->queued_bios)) {
694 spin_unlock_irqrestore(&m->lock, flags);
695 return;
696 }
697
698 bio_list_merge(&bios, &m->queued_bios);
699 bio_list_init(&m->queued_bios);
700
701 spin_unlock_irqrestore(&m->lock, flags);
702
703 blk_start_plug(&plug);
704 while ((bio = bio_list_pop(&bios))) {
705 struct dm_mpath_io *mpio = get_mpio_from_bio(bio);
706 dm_bio_restore(get_bio_details_from_mpio(mpio), bio);
707 r = __multipath_map_bio(m, bio, mpio);
708 switch (r) {
709 case DM_MAPIO_KILL:
710 bio->bi_status = BLK_STS_IOERR;
711 bio_endio(bio);
712 break;
713 case DM_MAPIO_REQUEUE:
714 bio->bi_status = BLK_STS_DM_REQUEUE;
715 bio_endio(bio);
716 break;
717 case DM_MAPIO_REMAPPED:
718 submit_bio_noacct(bio);
719 break;
720 case DM_MAPIO_SUBMITTED:
721 break;
722 default:
723 WARN_ONCE(true, "__multipath_map_bio() returned %d\n", r);
724 }
725 }
726 blk_finish_plug(&plug);
727 }
728
729 /*
730 * If we run out of usable paths, should we queue I/O or error it?
731 */
732 static int queue_if_no_path(struct multipath *m, bool queue_if_no_path,
733 bool save_old_value, const char *caller)
734 {
735 unsigned long flags;
736 bool queue_if_no_path_bit, saved_queue_if_no_path_bit;
737 const char *dm_dev_name = dm_table_device_name(m->ti->table);
738
739 DMDEBUG("%s: %s caller=%s queue_if_no_path=%d save_old_value=%d",
740 dm_dev_name, __func__, caller, queue_if_no_path, save_old_value);
741
742 spin_lock_irqsave(&m->lock, flags);
743
744 queue_if_no_path_bit = test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
745 saved_queue_if_no_path_bit = test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
746
747 if (save_old_value) {
748 if (unlikely(!queue_if_no_path_bit && saved_queue_if_no_path_bit)) {
749 DMERR("%s: QIFNP disabled but saved as enabled, saving again loses state, not saving!",
750 dm_dev_name);
751 } else
752 assign_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags, queue_if_no_path_bit);
753 } else if (!queue_if_no_path && saved_queue_if_no_path_bit) {
754 /* due to "fail_if_no_path" message, need to honor it. */
755 clear_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
756 }
757 assign_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags, queue_if_no_path);
758
759 DMDEBUG("%s: after %s changes; QIFNP = %d; SQIFNP = %d; DNFS = %d",
760 dm_dev_name, __func__,
761 test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags),
762 test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags),
763 dm_noflush_suspending(m->ti));
764
765 spin_unlock_irqrestore(&m->lock, flags);
766
767 if (!queue_if_no_path) {
768 dm_table_run_md_queue_async(m->ti->table);
769 process_queued_io_list(m);
770 }
771
772 return 0;
773 }
774
775 /*
776 * If the queue_if_no_path timeout fires, turn off queue_if_no_path and
777 * process any queued I/O.
778 */
779 static void queue_if_no_path_timeout_work(struct timer_list *t)
780 {
781 struct multipath *m = from_timer(m, t, nopath_timer);
782
783 DMWARN("queue_if_no_path timeout on %s, failing queued IO",
784 dm_table_device_name(m->ti->table));
785 queue_if_no_path(m, false, false, __func__);
786 }
787
788 /*
789 * Enable the queue_if_no_path timeout if necessary.
790 * Called with m->lock held.
791 */
792 static void enable_nopath_timeout(struct multipath *m)
793 {
794 unsigned long queue_if_no_path_timeout =
795 READ_ONCE(queue_if_no_path_timeout_secs) * HZ;
796
797 lockdep_assert_held(&m->lock);
798
799 if (queue_if_no_path_timeout > 0 &&
800 atomic_read(&m->nr_valid_paths) == 0 &&
801 test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
802 mod_timer(&m->nopath_timer,
803 jiffies + queue_if_no_path_timeout);
804 }
805 }
806
807 static void disable_nopath_timeout(struct multipath *m)
808 {
809 del_timer_sync(&m->nopath_timer);
810 }
811
812 /*
813 * An event is triggered whenever a path is taken out of use.
814 * Includes path failure and PG bypass.
815 */
816 static void trigger_event(struct work_struct *work)
817 {
818 struct multipath *m =
819 container_of(work, struct multipath, trigger_event);
820
821 dm_table_event(m->ti->table);
822 }
823
824 /*-----------------------------------------------------------------
825 * Constructor/argument parsing:
826 * <#multipath feature args> [<arg>]*
827 * <#hw_handler args> [hw_handler [<arg>]*]
828 * <#priority groups>
829 * <initial priority group>
830 * [<selector> <#selector args> [<arg>]*
831 * <#paths> <#per-path selector args>
832 * [<path> [<arg>]* ]+ ]+
833 *---------------------------------------------------------------*/
834 static int parse_path_selector(struct dm_arg_set *as, struct priority_group *pg,
835 struct dm_target *ti)
836 {
837 int r;
838 struct path_selector_type *pst;
839 unsigned ps_argc;
840
841 static const struct dm_arg _args[] = {
842 {0, 1024, "invalid number of path selector args"},
843 };
844
845 pst = dm_get_path_selector(dm_shift_arg(as));
846 if (!pst) {
847 ti->error = "unknown path selector type";
848 return -EINVAL;
849 }
850
851 r = dm_read_arg_group(_args, as, &ps_argc, &ti->error);
852 if (r) {
853 dm_put_path_selector(pst);
854 return -EINVAL;
855 }
856
857 r = pst->create(&pg->ps, ps_argc, as->argv);
858 if (r) {
859 dm_put_path_selector(pst);
860 ti->error = "path selector constructor failed";
861 return r;
862 }
863
864 pg->ps.type = pst;
865 dm_consume_args(as, ps_argc);
866
867 return 0;
868 }
869
870 static int setup_scsi_dh(struct block_device *bdev, struct multipath *m,
871 const char **attached_handler_name, char **error)
872 {
873 struct request_queue *q = bdev_get_queue(bdev);
874 int r;
875
876 if (mpath_double_check_test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, m)) {
877 retain:
878 if (*attached_handler_name) {
879 /*
880 * Clear any hw_handler_params associated with a
881 * handler that isn't already attached.
882 */
883 if (m->hw_handler_name && strcmp(*attached_handler_name, m->hw_handler_name)) {
884 kfree(m->hw_handler_params);
885 m->hw_handler_params = NULL;
886 }
887
888 /*
889 * Reset hw_handler_name to match the attached handler
890 *
891 * NB. This modifies the table line to show the actual
892 * handler instead of the original table passed in.
893 */
894 kfree(m->hw_handler_name);
895 m->hw_handler_name = *attached_handler_name;
896 *attached_handler_name = NULL;
897 }
898 }
899
900 if (m->hw_handler_name) {
901 r = scsi_dh_attach(q, m->hw_handler_name);
902 if (r == -EBUSY) {
903 char b[BDEVNAME_SIZE];
904
905 printk(KERN_INFO "dm-mpath: retaining handler on device %s\n",
906 bdevname(bdev, b));
907 goto retain;
908 }
909 if (r < 0) {
910 *error = "error attaching hardware handler";
911 return r;
912 }
913
914 if (m->hw_handler_params) {
915 r = scsi_dh_set_params(q, m->hw_handler_params);
916 if (r < 0) {
917 *error = "unable to set hardware handler parameters";
918 return r;
919 }
920 }
921 }
922
923 return 0;
924 }
925
926 static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps,
927 struct dm_target *ti)
928 {
929 int r;
930 struct pgpath *p;
931 struct multipath *m = ti->private;
932 struct request_queue *q;
933 const char *attached_handler_name = NULL;
934
935 /* we need at least a path arg */
936 if (as->argc < 1) {
937 ti->error = "no device given";
938 return ERR_PTR(-EINVAL);
939 }
940
941 p = alloc_pgpath();
942 if (!p)
943 return ERR_PTR(-ENOMEM);
944
945 r = dm_get_device(ti, dm_shift_arg(as), dm_table_get_mode(ti->table),
946 &p->path.dev);
947 if (r) {
948 ti->error = "error getting device";
949 goto bad;
950 }
951
952 q = bdev_get_queue(p->path.dev->bdev);
953 attached_handler_name = scsi_dh_attached_handler_name(q, GFP_KERNEL);
954 if (attached_handler_name || m->hw_handler_name) {
955 INIT_DELAYED_WORK(&p->activate_path, activate_path_work);
956 r = setup_scsi_dh(p->path.dev->bdev, m, &attached_handler_name, &ti->error);
957 kfree(attached_handler_name);
958 if (r) {
959 dm_put_device(ti, p->path.dev);
960 goto bad;
961 }
962 }
963
964 r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
965 if (r) {
966 dm_put_device(ti, p->path.dev);
967 goto bad;
968 }
969
970 return p;
971 bad:
972 free_pgpath(p);
973 return ERR_PTR(r);
974 }
975
976 static struct priority_group *parse_priority_group(struct dm_arg_set *as,
977 struct multipath *m)
978 {
979 static const struct dm_arg _args[] = {
980 {1, 1024, "invalid number of paths"},
981 {0, 1024, "invalid number of selector args"}
982 };
983
984 int r;
985 unsigned i, nr_selector_args, nr_args;
986 struct priority_group *pg;
987 struct dm_target *ti = m->ti;
988
989 if (as->argc < 2) {
990 as->argc = 0;
991 ti->error = "not enough priority group arguments";
992 return ERR_PTR(-EINVAL);
993 }
994
995 pg = alloc_priority_group();
996 if (!pg) {
997 ti->error = "couldn't allocate priority group";
998 return ERR_PTR(-ENOMEM);
999 }
1000 pg->m = m;
1001
1002 r = parse_path_selector(as, pg, ti);
1003 if (r)
1004 goto bad;
1005
1006 /*
1007 * read the paths
1008 */
1009 r = dm_read_arg(_args, as, &pg->nr_pgpaths, &ti->error);
1010 if (r)
1011 goto bad;
1012
1013 r = dm_read_arg(_args + 1, as, &nr_selector_args, &ti->error);
1014 if (r)
1015 goto bad;
1016
1017 nr_args = 1 + nr_selector_args;
1018 for (i = 0; i < pg->nr_pgpaths; i++) {
1019 struct pgpath *pgpath;
1020 struct dm_arg_set path_args;
1021
1022 if (as->argc < nr_args) {
1023 ti->error = "not enough path parameters";
1024 r = -EINVAL;
1025 goto bad;
1026 }
1027
1028 path_args.argc = nr_args;
1029 path_args.argv = as->argv;
1030
1031 pgpath = parse_path(&path_args, &pg->ps, ti);
1032 if (IS_ERR(pgpath)) {
1033 r = PTR_ERR(pgpath);
1034 goto bad;
1035 }
1036
1037 pgpath->pg = pg;
1038 list_add_tail(&pgpath->list, &pg->pgpaths);
1039 dm_consume_args(as, nr_args);
1040 }
1041
1042 return pg;
1043
1044 bad:
1045 free_priority_group(pg, ti);
1046 return ERR_PTR(r);
1047 }
1048
1049 static int parse_hw_handler(struct dm_arg_set *as, struct multipath *m)
1050 {
1051 unsigned hw_argc;
1052 int ret;
1053 struct dm_target *ti = m->ti;
1054
1055 static const struct dm_arg _args[] = {
1056 {0, 1024, "invalid number of hardware handler args"},
1057 };
1058
1059 if (dm_read_arg_group(_args, as, &hw_argc, &ti->error))
1060 return -EINVAL;
1061
1062 if (!hw_argc)
1063 return 0;
1064
1065 if (m->queue_mode == DM_TYPE_BIO_BASED) {
1066 dm_consume_args(as, hw_argc);
1067 DMERR("bio-based multipath doesn't allow hardware handler args");
1068 return 0;
1069 }
1070
1071 m->hw_handler_name = kstrdup(dm_shift_arg(as), GFP_KERNEL);
1072 if (!m->hw_handler_name)
1073 return -EINVAL;
1074
1075 if (hw_argc > 1) {
1076 char *p;
1077 int i, j, len = 4;
1078
1079 for (i = 0; i <= hw_argc - 2; i++)
1080 len += strlen(as->argv[i]) + 1;
1081 p = m->hw_handler_params = kzalloc(len, GFP_KERNEL);
1082 if (!p) {
1083 ti->error = "memory allocation failed";
1084 ret = -ENOMEM;
1085 goto fail;
1086 }
1087 j = sprintf(p, "%d", hw_argc - 1);
1088 for (i = 0, p+=j+1; i <= hw_argc - 2; i++, p+=j+1)
1089 j = sprintf(p, "%s", as->argv[i]);
1090 }
1091 dm_consume_args(as, hw_argc - 1);
1092
1093 return 0;
1094 fail:
1095 kfree(m->hw_handler_name);
1096 m->hw_handler_name = NULL;
1097 return ret;
1098 }
1099
1100 static int parse_features(struct dm_arg_set *as, struct multipath *m)
1101 {
1102 int r;
1103 unsigned argc;
1104 struct dm_target *ti = m->ti;
1105 const char *arg_name;
1106
1107 static const struct dm_arg _args[] = {
1108 {0, 8, "invalid number of feature args"},
1109 {1, 50, "pg_init_retries must be between 1 and 50"},
1110 {0, 60000, "pg_init_delay_msecs must be between 0 and 60000"},
1111 };
1112
1113 r = dm_read_arg_group(_args, as, &argc, &ti->error);
1114 if (r)
1115 return -EINVAL;
1116
1117 if (!argc)
1118 return 0;
1119
1120 do {
1121 arg_name = dm_shift_arg(as);
1122 argc--;
1123
1124 if (!strcasecmp(arg_name, "queue_if_no_path")) {
1125 r = queue_if_no_path(m, true, false, __func__);
1126 continue;
1127 }
1128
1129 if (!strcasecmp(arg_name, "retain_attached_hw_handler")) {
1130 set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags);
1131 continue;
1132 }
1133
1134 if (!strcasecmp(arg_name, "pg_init_retries") &&
1135 (argc >= 1)) {
1136 r = dm_read_arg(_args + 1, as, &m->pg_init_retries, &ti->error);
1137 argc--;
1138 continue;
1139 }
1140
1141 if (!strcasecmp(arg_name, "pg_init_delay_msecs") &&
1142 (argc >= 1)) {
1143 r = dm_read_arg(_args + 2, as, &m->pg_init_delay_msecs, &ti->error);
1144 argc--;
1145 continue;
1146 }
1147
1148 if (!strcasecmp(arg_name, "queue_mode") &&
1149 (argc >= 1)) {
1150 const char *queue_mode_name = dm_shift_arg(as);
1151
1152 if (!strcasecmp(queue_mode_name, "bio"))
1153 m->queue_mode = DM_TYPE_BIO_BASED;
1154 else if (!strcasecmp(queue_mode_name, "rq") ||
1155 !strcasecmp(queue_mode_name, "mq"))
1156 m->queue_mode = DM_TYPE_REQUEST_BASED;
1157 else {
1158 ti->error = "Unknown 'queue_mode' requested";
1159 r = -EINVAL;
1160 }
1161 argc--;
1162 continue;
1163 }
1164
1165 ti->error = "Unrecognised multipath feature request";
1166 r = -EINVAL;
1167 } while (argc && !r);
1168
1169 return r;
1170 }
1171
1172 static int multipath_ctr(struct dm_target *ti, unsigned argc, char **argv)
1173 {
1174 /* target arguments */
1175 static const struct dm_arg _args[] = {
1176 {0, 1024, "invalid number of priority groups"},
1177 {0, 1024, "invalid initial priority group number"},
1178 };
1179
1180 int r;
1181 struct multipath *m;
1182 struct dm_arg_set as;
1183 unsigned pg_count = 0;
1184 unsigned next_pg_num;
1185 unsigned long flags;
1186
1187 as.argc = argc;
1188 as.argv = argv;
1189
1190 m = alloc_multipath(ti);
1191 if (!m) {
1192 ti->error = "can't allocate multipath";
1193 return -EINVAL;
1194 }
1195
1196 r = parse_features(&as, m);
1197 if (r)
1198 goto bad;
1199
1200 r = alloc_multipath_stage2(ti, m);
1201 if (r)
1202 goto bad;
1203
1204 r = parse_hw_handler(&as, m);
1205 if (r)
1206 goto bad;
1207
1208 r = dm_read_arg(_args, &as, &m->nr_priority_groups, &ti->error);
1209 if (r)
1210 goto bad;
1211
1212 r = dm_read_arg(_args + 1, &as, &next_pg_num, &ti->error);
1213 if (r)
1214 goto bad;
1215
1216 if ((!m->nr_priority_groups && next_pg_num) ||
1217 (m->nr_priority_groups && !next_pg_num)) {
1218 ti->error = "invalid initial priority group";
1219 r = -EINVAL;
1220 goto bad;
1221 }
1222
1223 /* parse the priority groups */
1224 while (as.argc) {
1225 struct priority_group *pg;
1226 unsigned nr_valid_paths = atomic_read(&m->nr_valid_paths);
1227
1228 pg = parse_priority_group(&as, m);
1229 if (IS_ERR(pg)) {
1230 r = PTR_ERR(pg);
1231 goto bad;
1232 }
1233
1234 nr_valid_paths += pg->nr_pgpaths;
1235 atomic_set(&m->nr_valid_paths, nr_valid_paths);
1236
1237 list_add_tail(&pg->list, &m->priority_groups);
1238 pg_count++;
1239 pg->pg_num = pg_count;
1240 if (!--next_pg_num)
1241 m->next_pg = pg;
1242 }
1243
1244 if (pg_count != m->nr_priority_groups) {
1245 ti->error = "priority group count mismatch";
1246 r = -EINVAL;
1247 goto bad;
1248 }
1249
1250 spin_lock_irqsave(&m->lock, flags);
1251 enable_nopath_timeout(m);
1252 spin_unlock_irqrestore(&m->lock, flags);
1253
1254 ti->num_flush_bios = 1;
1255 ti->num_discard_bios = 1;
1256 ti->num_write_same_bios = 1;
1257 ti->num_write_zeroes_bios = 1;
1258 if (m->queue_mode == DM_TYPE_BIO_BASED)
1259 ti->per_io_data_size = multipath_per_bio_data_size();
1260 else
1261 ti->per_io_data_size = sizeof(struct dm_mpath_io);
1262
1263 return 0;
1264
1265 bad:
1266 free_multipath(m);
1267 return r;
1268 }
1269
1270 static void multipath_wait_for_pg_init_completion(struct multipath *m)
1271 {
1272 DEFINE_WAIT(wait);
1273
1274 while (1) {
1275 prepare_to_wait(&m->pg_init_wait, &wait, TASK_UNINTERRUPTIBLE);
1276
1277 if (!atomic_read(&m->pg_init_in_progress))
1278 break;
1279
1280 io_schedule();
1281 }
1282 finish_wait(&m->pg_init_wait, &wait);
1283 }
1284
1285 static void flush_multipath_work(struct multipath *m)
1286 {
1287 if (m->hw_handler_name) {
1288 unsigned long flags;
1289
1290 if (!atomic_read(&m->pg_init_in_progress))
1291 goto skip;
1292
1293 spin_lock_irqsave(&m->lock, flags);
1294 if (atomic_read(&m->pg_init_in_progress) &&
1295 !test_and_set_bit(MPATHF_PG_INIT_DISABLED, &m->flags)) {
1296 spin_unlock_irqrestore(&m->lock, flags);
1297
1298 flush_workqueue(kmpath_handlerd);
1299 multipath_wait_for_pg_init_completion(m);
1300
1301 spin_lock_irqsave(&m->lock, flags);
1302 clear_bit(MPATHF_PG_INIT_DISABLED, &m->flags);
1303 }
1304 spin_unlock_irqrestore(&m->lock, flags);
1305 }
1306 skip:
1307 if (m->queue_mode == DM_TYPE_BIO_BASED)
1308 flush_work(&m->process_queued_bios);
1309 flush_work(&m->trigger_event);
1310 }
1311
1312 static void multipath_dtr(struct dm_target *ti)
1313 {
1314 struct multipath *m = ti->private;
1315
1316 disable_nopath_timeout(m);
1317 flush_multipath_work(m);
1318 free_multipath(m);
1319 }
1320
1321 /*
1322 * Take a path out of use.
1323 */
1324 static int fail_path(struct pgpath *pgpath)
1325 {
1326 unsigned long flags;
1327 struct multipath *m = pgpath->pg->m;
1328
1329 spin_lock_irqsave(&m->lock, flags);
1330
1331 if (!pgpath->is_active)
1332 goto out;
1333
1334 DMWARN("%s: Failing path %s.",
1335 dm_table_device_name(m->ti->table),
1336 pgpath->path.dev->name);
1337
1338 pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
1339 pgpath->is_active = false;
1340 pgpath->fail_count++;
1341
1342 atomic_dec(&m->nr_valid_paths);
1343
1344 if (pgpath == m->current_pgpath)
1345 m->current_pgpath = NULL;
1346
1347 dm_path_uevent(DM_UEVENT_PATH_FAILED, m->ti,
1348 pgpath->path.dev->name, atomic_read(&m->nr_valid_paths));
1349
1350 schedule_work(&m->trigger_event);
1351
1352 enable_nopath_timeout(m);
1353
1354 out:
1355 spin_unlock_irqrestore(&m->lock, flags);
1356
1357 return 0;
1358 }
1359
1360 /*
1361 * Reinstate a previously-failed path
1362 */
1363 static int reinstate_path(struct pgpath *pgpath)
1364 {
1365 int r = 0, run_queue = 0;
1366 unsigned long flags;
1367 struct multipath *m = pgpath->pg->m;
1368 unsigned nr_valid_paths;
1369
1370 spin_lock_irqsave(&m->lock, flags);
1371
1372 if (pgpath->is_active)
1373 goto out;
1374
1375 DMWARN("%s: Reinstating path %s.",
1376 dm_table_device_name(m->ti->table),
1377 pgpath->path.dev->name);
1378
1379 r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
1380 if (r)
1381 goto out;
1382
1383 pgpath->is_active = true;
1384
1385 nr_valid_paths = atomic_inc_return(&m->nr_valid_paths);
1386 if (nr_valid_paths == 1) {
1387 m->current_pgpath = NULL;
1388 run_queue = 1;
1389 } else if (m->hw_handler_name && (m->current_pg == pgpath->pg)) {
1390 if (queue_work(kmpath_handlerd, &pgpath->activate_path.work))
1391 atomic_inc(&m->pg_init_in_progress);
1392 }
1393
1394 dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti,
1395 pgpath->path.dev->name, nr_valid_paths);
1396
1397 schedule_work(&m->trigger_event);
1398
1399 out:
1400 spin_unlock_irqrestore(&m->lock, flags);
1401 if (run_queue) {
1402 dm_table_run_md_queue_async(m->ti->table);
1403 process_queued_io_list(m);
1404 }
1405
1406 if (pgpath->is_active)
1407 disable_nopath_timeout(m);
1408
1409 return r;
1410 }
1411
1412 /*
1413 * Fail or reinstate all paths that match the provided struct dm_dev.
1414 */
1415 static int action_dev(struct multipath *m, struct dm_dev *dev,
1416 action_fn action)
1417 {
1418 int r = -EINVAL;
1419 struct pgpath *pgpath;
1420 struct priority_group *pg;
1421
1422 list_for_each_entry(pg, &m->priority_groups, list) {
1423 list_for_each_entry(pgpath, &pg->pgpaths, list) {
1424 if (pgpath->path.dev == dev)
1425 r = action(pgpath);
1426 }
1427 }
1428
1429 return r;
1430 }
1431
1432 /*
1433 * Temporarily try to avoid having to use the specified PG
1434 */
1435 static void bypass_pg(struct multipath *m, struct priority_group *pg,
1436 bool bypassed)
1437 {
1438 unsigned long flags;
1439
1440 spin_lock_irqsave(&m->lock, flags);
1441
1442 pg->bypassed = bypassed;
1443 m->current_pgpath = NULL;
1444 m->current_pg = NULL;
1445
1446 spin_unlock_irqrestore(&m->lock, flags);
1447
1448 schedule_work(&m->trigger_event);
1449 }
1450
1451 /*
1452 * Switch to using the specified PG from the next I/O that gets mapped
1453 */
1454 static int switch_pg_num(struct multipath *m, const char *pgstr)
1455 {
1456 struct priority_group *pg;
1457 unsigned pgnum;
1458 unsigned long flags;
1459 char dummy;
1460
1461 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1462 !m->nr_priority_groups || (pgnum > m->nr_priority_groups)) {
1463 DMWARN("invalid PG number supplied to switch_pg_num");
1464 return -EINVAL;
1465 }
1466
1467 spin_lock_irqsave(&m->lock, flags);
1468 list_for_each_entry(pg, &m->priority_groups, list) {
1469 pg->bypassed = false;
1470 if (--pgnum)
1471 continue;
1472
1473 m->current_pgpath = NULL;
1474 m->current_pg = NULL;
1475 m->next_pg = pg;
1476 }
1477 spin_unlock_irqrestore(&m->lock, flags);
1478
1479 schedule_work(&m->trigger_event);
1480 return 0;
1481 }
1482
1483 /*
1484 * Set/clear bypassed status of a PG.
1485 * PGs are numbered upwards from 1 in the order they were declared.
1486 */
1487 static int bypass_pg_num(struct multipath *m, const char *pgstr, bool bypassed)
1488 {
1489 struct priority_group *pg;
1490 unsigned pgnum;
1491 char dummy;
1492
1493 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1494 !m->nr_priority_groups || (pgnum > m->nr_priority_groups)) {
1495 DMWARN("invalid PG number supplied to bypass_pg");
1496 return -EINVAL;
1497 }
1498
1499 list_for_each_entry(pg, &m->priority_groups, list) {
1500 if (!--pgnum)
1501 break;
1502 }
1503
1504 bypass_pg(m, pg, bypassed);
1505 return 0;
1506 }
1507
1508 /*
1509 * Should we retry pg_init immediately?
1510 */
1511 static bool pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath)
1512 {
1513 unsigned long flags;
1514 bool limit_reached = false;
1515
1516 spin_lock_irqsave(&m->lock, flags);
1517
1518 if (atomic_read(&m->pg_init_count) <= m->pg_init_retries &&
1519 !test_bit(MPATHF_PG_INIT_DISABLED, &m->flags))
1520 set_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
1521 else
1522 limit_reached = true;
1523
1524 spin_unlock_irqrestore(&m->lock, flags);
1525
1526 return limit_reached;
1527 }
1528
1529 static void pg_init_done(void *data, int errors)
1530 {
1531 struct pgpath *pgpath = data;
1532 struct priority_group *pg = pgpath->pg;
1533 struct multipath *m = pg->m;
1534 unsigned long flags;
1535 bool delay_retry = false;
1536
1537 /* device or driver problems */
1538 switch (errors) {
1539 case SCSI_DH_OK:
1540 break;
1541 case SCSI_DH_NOSYS:
1542 if (!m->hw_handler_name) {
1543 errors = 0;
1544 break;
1545 }
1546 DMERR("Could not failover the device: Handler scsi_dh_%s "
1547 "Error %d.", m->hw_handler_name, errors);
1548 /*
1549 * Fail path for now, so we do not ping pong
1550 */
1551 fail_path(pgpath);
1552 break;
1553 case SCSI_DH_DEV_TEMP_BUSY:
1554 /*
1555 * Probably doing something like FW upgrade on the
1556 * controller so try the other pg.
1557 */
1558 bypass_pg(m, pg, true);
1559 break;
1560 case SCSI_DH_RETRY:
1561 /* Wait before retrying. */
1562 delay_retry = true;
1563 fallthrough;
1564 case SCSI_DH_IMM_RETRY:
1565 case SCSI_DH_RES_TEMP_UNAVAIL:
1566 if (pg_init_limit_reached(m, pgpath))
1567 fail_path(pgpath);
1568 errors = 0;
1569 break;
1570 case SCSI_DH_DEV_OFFLINED:
1571 default:
1572 /*
1573 * We probably do not want to fail the path for a device
1574 * error, but this is what the old dm did. In future
1575 * patches we can do more advanced handling.
1576 */
1577 fail_path(pgpath);
1578 }
1579
1580 spin_lock_irqsave(&m->lock, flags);
1581 if (errors) {
1582 if (pgpath == m->current_pgpath) {
1583 DMERR("Could not failover device. Error %d.", errors);
1584 m->current_pgpath = NULL;
1585 m->current_pg = NULL;
1586 }
1587 } else if (!test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
1588 pg->bypassed = false;
1589
1590 if (atomic_dec_return(&m->pg_init_in_progress) > 0)
1591 /* Activations of other paths are still on going */
1592 goto out;
1593
1594 if (test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags)) {
1595 if (delay_retry)
1596 set_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
1597 else
1598 clear_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
1599
1600 if (__pg_init_all_paths(m))
1601 goto out;
1602 }
1603 clear_bit(MPATHF_QUEUE_IO, &m->flags);
1604
1605 process_queued_io_list(m);
1606
1607 /*
1608 * Wake up any thread waiting to suspend.
1609 */
1610 wake_up(&m->pg_init_wait);
1611
1612 out:
1613 spin_unlock_irqrestore(&m->lock, flags);
1614 }
1615
1616 static void activate_or_offline_path(struct pgpath *pgpath)
1617 {
1618 struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
1619
1620 if (pgpath->is_active && !blk_queue_dying(q))
1621 scsi_dh_activate(q, pg_init_done, pgpath);
1622 else
1623 pg_init_done(pgpath, SCSI_DH_DEV_OFFLINED);
1624 }
1625
1626 static void activate_path_work(struct work_struct *work)
1627 {
1628 struct pgpath *pgpath =
1629 container_of(work, struct pgpath, activate_path.work);
1630
1631 activate_or_offline_path(pgpath);
1632 }
1633
1634 static int multipath_end_io(struct dm_target *ti, struct request *clone,
1635 blk_status_t error, union map_info *map_context)
1636 {
1637 struct dm_mpath_io *mpio = get_mpio(map_context);
1638 struct pgpath *pgpath = mpio->pgpath;
1639 int r = DM_ENDIO_DONE;
1640
1641 /*
1642 * We don't queue any clone request inside the multipath target
1643 * during end I/O handling, since those clone requests don't have
1644 * bio clones. If we queue them inside the multipath target,
1645 * we need to make bio clones, that requires memory allocation.
1646 * (See drivers/md/dm-rq.c:end_clone_bio() about why the clone requests
1647 * don't have bio clones.)
1648 * Instead of queueing the clone request here, we queue the original
1649 * request into dm core, which will remake a clone request and
1650 * clone bios for it and resubmit it later.
1651 */
1652 if (error && blk_path_error(error)) {
1653 struct multipath *m = ti->private;
1654
1655 if (error == BLK_STS_RESOURCE)
1656 r = DM_ENDIO_DELAY_REQUEUE;
1657 else
1658 r = DM_ENDIO_REQUEUE;
1659
1660 if (pgpath)
1661 fail_path(pgpath);
1662
1663 if (!atomic_read(&m->nr_valid_paths) &&
1664 !must_push_back_rq(m)) {
1665 if (error == BLK_STS_IOERR)
1666 dm_report_EIO(m);
1667 /* complete with the original error */
1668 r = DM_ENDIO_DONE;
1669 }
1670 }
1671
1672 if (pgpath) {
1673 struct path_selector *ps = &pgpath->pg->ps;
1674
1675 if (ps->type->end_io)
1676 ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes,
1677 clone->io_start_time_ns);
1678 }
1679
1680 return r;
1681 }
1682
1683 static int multipath_end_io_bio(struct dm_target *ti, struct bio *clone,
1684 blk_status_t *error)
1685 {
1686 struct multipath *m = ti->private;
1687 struct dm_mpath_io *mpio = get_mpio_from_bio(clone);
1688 struct pgpath *pgpath = mpio->pgpath;
1689 unsigned long flags;
1690 int r = DM_ENDIO_DONE;
1691
1692 if (!*error || !blk_path_error(*error))
1693 goto done;
1694
1695 if (pgpath)
1696 fail_path(pgpath);
1697
1698 if (!atomic_read(&m->nr_valid_paths)) {
1699 spin_lock_irqsave(&m->lock, flags);
1700 if (!test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
1701 if (__must_push_back(m)) {
1702 r = DM_ENDIO_REQUEUE;
1703 } else {
1704 dm_report_EIO(m);
1705 *error = BLK_STS_IOERR;
1706 }
1707 spin_unlock_irqrestore(&m->lock, flags);
1708 goto done;
1709 }
1710 spin_unlock_irqrestore(&m->lock, flags);
1711 }
1712
1713 multipath_queue_bio(m, clone);
1714 r = DM_ENDIO_INCOMPLETE;
1715 done:
1716 if (pgpath) {
1717 struct path_selector *ps = &pgpath->pg->ps;
1718
1719 if (ps->type->end_io)
1720 ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes,
1721 dm_start_time_ns_from_clone(clone));
1722 }
1723
1724 return r;
1725 }
1726
1727 /*
1728 * Suspend with flush can't complete until all the I/O is processed
1729 * so if the last path fails we must error any remaining I/O.
1730 * - Note that if the freeze_bdev fails while suspending, the
1731 * queue_if_no_path state is lost - userspace should reset it.
1732 * Otherwise, during noflush suspend, queue_if_no_path will not change.
1733 */
1734 static void multipath_presuspend(struct dm_target *ti)
1735 {
1736 struct multipath *m = ti->private;
1737
1738 /* FIXME: bio-based shouldn't need to always disable queue_if_no_path */
1739 if (m->queue_mode == DM_TYPE_BIO_BASED || !dm_noflush_suspending(m->ti))
1740 queue_if_no_path(m, false, true, __func__);
1741 }
1742
1743 static void multipath_postsuspend(struct dm_target *ti)
1744 {
1745 struct multipath *m = ti->private;
1746
1747 mutex_lock(&m->work_mutex);
1748 flush_multipath_work(m);
1749 mutex_unlock(&m->work_mutex);
1750 }
1751
1752 /*
1753 * Restore the queue_if_no_path setting.
1754 */
1755 static void multipath_resume(struct dm_target *ti)
1756 {
1757 struct multipath *m = ti->private;
1758 unsigned long flags;
1759
1760 spin_lock_irqsave(&m->lock, flags);
1761 if (test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags)) {
1762 set_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
1763 clear_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
1764 }
1765
1766 DMDEBUG("%s: %s finished; QIFNP = %d; SQIFNP = %d",
1767 dm_table_device_name(m->ti->table), __func__,
1768 test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags),
1769 test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags));
1770
1771 spin_unlock_irqrestore(&m->lock, flags);
1772 }
1773
1774 /*
1775 * Info output has the following format:
1776 * num_multipath_feature_args [multipath_feature_args]*
1777 * num_handler_status_args [handler_status_args]*
1778 * num_groups init_group_number
1779 * [A|D|E num_ps_status_args [ps_status_args]*
1780 * num_paths num_selector_args
1781 * [path_dev A|F fail_count [selector_args]* ]+ ]+
1782 *
1783 * Table output has the following format (identical to the constructor string):
1784 * num_feature_args [features_args]*
1785 * num_handler_args hw_handler [hw_handler_args]*
1786 * num_groups init_group_number
1787 * [priority selector-name num_ps_args [ps_args]*
1788 * num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
1789 */
1790 static void multipath_status(struct dm_target *ti, status_type_t type,
1791 unsigned status_flags, char *result, unsigned maxlen)
1792 {
1793 int sz = 0;
1794 unsigned long flags;
1795 struct multipath *m = ti->private;
1796 struct priority_group *pg;
1797 struct pgpath *p;
1798 unsigned pg_num;
1799 char state;
1800
1801 spin_lock_irqsave(&m->lock, flags);
1802
1803 /* Features */
1804 if (type == STATUSTYPE_INFO)
1805 DMEMIT("2 %u %u ", test_bit(MPATHF_QUEUE_IO, &m->flags),
1806 atomic_read(&m->pg_init_count));
1807 else {
1808 DMEMIT("%u ", test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) +
1809 (m->pg_init_retries > 0) * 2 +
1810 (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT) * 2 +
1811 test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags) +
1812 (m->queue_mode != DM_TYPE_REQUEST_BASED) * 2);
1813
1814 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
1815 DMEMIT("queue_if_no_path ");
1816 if (m->pg_init_retries)
1817 DMEMIT("pg_init_retries %u ", m->pg_init_retries);
1818 if (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT)
1819 DMEMIT("pg_init_delay_msecs %u ", m->pg_init_delay_msecs);
1820 if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags))
1821 DMEMIT("retain_attached_hw_handler ");
1822 if (m->queue_mode != DM_TYPE_REQUEST_BASED) {
1823 switch(m->queue_mode) {
1824 case DM_TYPE_BIO_BASED:
1825 DMEMIT("queue_mode bio ");
1826 break;
1827 default:
1828 WARN_ON_ONCE(true);
1829 break;
1830 }
1831 }
1832 }
1833
1834 if (!m->hw_handler_name || type == STATUSTYPE_INFO)
1835 DMEMIT("0 ");
1836 else
1837 DMEMIT("1 %s ", m->hw_handler_name);
1838
1839 DMEMIT("%u ", m->nr_priority_groups);
1840
1841 if (m->next_pg)
1842 pg_num = m->next_pg->pg_num;
1843 else if (m->current_pg)
1844 pg_num = m->current_pg->pg_num;
1845 else
1846 pg_num = (m->nr_priority_groups ? 1 : 0);
1847
1848 DMEMIT("%u ", pg_num);
1849
1850 switch (type) {
1851 case STATUSTYPE_INFO:
1852 list_for_each_entry(pg, &m->priority_groups, list) {
1853 if (pg->bypassed)
1854 state = 'D'; /* Disabled */
1855 else if (pg == m->current_pg)
1856 state = 'A'; /* Currently Active */
1857 else
1858 state = 'E'; /* Enabled */
1859
1860 DMEMIT("%c ", state);
1861
1862 if (pg->ps.type->status)
1863 sz += pg->ps.type->status(&pg->ps, NULL, type,
1864 result + sz,
1865 maxlen - sz);
1866 else
1867 DMEMIT("0 ");
1868
1869 DMEMIT("%u %u ", pg->nr_pgpaths,
1870 pg->ps.type->info_args);
1871
1872 list_for_each_entry(p, &pg->pgpaths, list) {
1873 DMEMIT("%s %s %u ", p->path.dev->name,
1874 p->is_active ? "A" : "F",
1875 p->fail_count);
1876 if (pg->ps.type->status)
1877 sz += pg->ps.type->status(&pg->ps,
1878 &p->path, type, result + sz,
1879 maxlen - sz);
1880 }
1881 }
1882 break;
1883
1884 case STATUSTYPE_TABLE:
1885 list_for_each_entry(pg, &m->priority_groups, list) {
1886 DMEMIT("%s ", pg->ps.type->name);
1887
1888 if (pg->ps.type->status)
1889 sz += pg->ps.type->status(&pg->ps, NULL, type,
1890 result + sz,
1891 maxlen - sz);
1892 else
1893 DMEMIT("0 ");
1894
1895 DMEMIT("%u %u ", pg->nr_pgpaths,
1896 pg->ps.type->table_args);
1897
1898 list_for_each_entry(p, &pg->pgpaths, list) {
1899 DMEMIT("%s ", p->path.dev->name);
1900 if (pg->ps.type->status)
1901 sz += pg->ps.type->status(&pg->ps,
1902 &p->path, type, result + sz,
1903 maxlen - sz);
1904 }
1905 }
1906 break;
1907 }
1908
1909 spin_unlock_irqrestore(&m->lock, flags);
1910 }
1911
1912 static int multipath_message(struct dm_target *ti, unsigned argc, char **argv,
1913 char *result, unsigned maxlen)
1914 {
1915 int r = -EINVAL;
1916 struct dm_dev *dev;
1917 struct multipath *m = ti->private;
1918 action_fn action;
1919 unsigned long flags;
1920
1921 mutex_lock(&m->work_mutex);
1922
1923 if (dm_suspended(ti)) {
1924 r = -EBUSY;
1925 goto out;
1926 }
1927
1928 if (argc == 1) {
1929 if (!strcasecmp(argv[0], "queue_if_no_path")) {
1930 r = queue_if_no_path(m, true, false, __func__);
1931 spin_lock_irqsave(&m->lock, flags);
1932 enable_nopath_timeout(m);
1933 spin_unlock_irqrestore(&m->lock, flags);
1934 goto out;
1935 } else if (!strcasecmp(argv[0], "fail_if_no_path")) {
1936 r = queue_if_no_path(m, false, false, __func__);
1937 disable_nopath_timeout(m);
1938 goto out;
1939 }
1940 }
1941
1942 if (argc != 2) {
1943 DMWARN("Invalid multipath message arguments. Expected 2 arguments, got %d.", argc);
1944 goto out;
1945 }
1946
1947 if (!strcasecmp(argv[0], "disable_group")) {
1948 r = bypass_pg_num(m, argv[1], true);
1949 goto out;
1950 } else if (!strcasecmp(argv[0], "enable_group")) {
1951 r = bypass_pg_num(m, argv[1], false);
1952 goto out;
1953 } else if (!strcasecmp(argv[0], "switch_group")) {
1954 r = switch_pg_num(m, argv[1]);
1955 goto out;
1956 } else if (!strcasecmp(argv[0], "reinstate_path"))
1957 action = reinstate_path;
1958 else if (!strcasecmp(argv[0], "fail_path"))
1959 action = fail_path;
1960 else {
1961 DMWARN("Unrecognised multipath message received: %s", argv[0]);
1962 goto out;
1963 }
1964
1965 r = dm_get_device(ti, argv[1], dm_table_get_mode(ti->table), &dev);
1966 if (r) {
1967 DMWARN("message: error getting device %s",
1968 argv[1]);
1969 goto out;
1970 }
1971
1972 r = action_dev(m, dev, action);
1973
1974 dm_put_device(ti, dev);
1975
1976 out:
1977 mutex_unlock(&m->work_mutex);
1978 return r;
1979 }
1980
1981 static int multipath_prepare_ioctl(struct dm_target *ti,
1982 struct block_device **bdev)
1983 {
1984 struct multipath *m = ti->private;
1985 struct pgpath *pgpath;
1986 unsigned long flags;
1987 int r;
1988
1989 pgpath = READ_ONCE(m->current_pgpath);
1990 if (!pgpath || !mpath_double_check_test_bit(MPATHF_QUEUE_IO, m))
1991 pgpath = choose_pgpath(m, 0);
1992
1993 if (pgpath) {
1994 if (!mpath_double_check_test_bit(MPATHF_QUEUE_IO, m)) {
1995 *bdev = pgpath->path.dev->bdev;
1996 r = 0;
1997 } else {
1998 /* pg_init has not started or completed */
1999 r = -ENOTCONN;
2000 }
2001 } else {
2002 /* No path is available */
2003 r = -EIO;
2004 spin_lock_irqsave(&m->lock, flags);
2005 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
2006 r = -ENOTCONN;
2007 spin_unlock_irqrestore(&m->lock, flags);
2008 }
2009
2010 if (r == -ENOTCONN) {
2011 if (!READ_ONCE(m->current_pg)) {
2012 /* Path status changed, redo selection */
2013 (void) choose_pgpath(m, 0);
2014 }
2015 spin_lock_irqsave(&m->lock, flags);
2016 if (test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
2017 (void) __pg_init_all_paths(m);
2018 spin_unlock_irqrestore(&m->lock, flags);
2019 dm_table_run_md_queue_async(m->ti->table);
2020 process_queued_io_list(m);
2021 }
2022
2023 /*
2024 * Only pass ioctls through if the device sizes match exactly.
2025 */
2026 if (!r && ti->len != i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT)
2027 return 1;
2028 return r;
2029 }
2030
2031 static int multipath_iterate_devices(struct dm_target *ti,
2032 iterate_devices_callout_fn fn, void *data)
2033 {
2034 struct multipath *m = ti->private;
2035 struct priority_group *pg;
2036 struct pgpath *p;
2037 int ret = 0;
2038
2039 list_for_each_entry(pg, &m->priority_groups, list) {
2040 list_for_each_entry(p, &pg->pgpaths, list) {
2041 ret = fn(ti, p->path.dev, ti->begin, ti->len, data);
2042 if (ret)
2043 goto out;
2044 }
2045 }
2046
2047 out:
2048 return ret;
2049 }
2050
2051 static int pgpath_busy(struct pgpath *pgpath)
2052 {
2053 struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
2054
2055 return blk_lld_busy(q);
2056 }
2057
2058 /*
2059 * We return "busy", only when we can map I/Os but underlying devices
2060 * are busy (so even if we map I/Os now, the I/Os will wait on
2061 * the underlying queue).
2062 * In other words, if we want to kill I/Os or queue them inside us
2063 * due to map unavailability, we don't return "busy". Otherwise,
2064 * dm core won't give us the I/Os and we can't do what we want.
2065 */
2066 static int multipath_busy(struct dm_target *ti)
2067 {
2068 bool busy = false, has_active = false;
2069 struct multipath *m = ti->private;
2070 struct priority_group *pg, *next_pg;
2071 struct pgpath *pgpath;
2072
2073 /* pg_init in progress */
2074 if (atomic_read(&m->pg_init_in_progress))
2075 return true;
2076
2077 /* no paths available, for blk-mq: rely on IO mapping to delay requeue */
2078 if (!atomic_read(&m->nr_valid_paths)) {
2079 unsigned long flags;
2080 spin_lock_irqsave(&m->lock, flags);
2081 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
2082 spin_unlock_irqrestore(&m->lock, flags);
2083 return (m->queue_mode != DM_TYPE_REQUEST_BASED);
2084 }
2085 spin_unlock_irqrestore(&m->lock, flags);
2086 }
2087
2088 /* Guess which priority_group will be used at next mapping time */
2089 pg = READ_ONCE(m->current_pg);
2090 next_pg = READ_ONCE(m->next_pg);
2091 if (unlikely(!READ_ONCE(m->current_pgpath) && next_pg))
2092 pg = next_pg;
2093
2094 if (!pg) {
2095 /*
2096 * We don't know which pg will be used at next mapping time.
2097 * We don't call choose_pgpath() here to avoid to trigger
2098 * pg_init just by busy checking.
2099 * So we don't know whether underlying devices we will be using
2100 * at next mapping time are busy or not. Just try mapping.
2101 */
2102 return busy;
2103 }
2104
2105 /*
2106 * If there is one non-busy active path at least, the path selector
2107 * will be able to select it. So we consider such a pg as not busy.
2108 */
2109 busy = true;
2110 list_for_each_entry(pgpath, &pg->pgpaths, list) {
2111 if (pgpath->is_active) {
2112 has_active = true;
2113 if (!pgpath_busy(pgpath)) {
2114 busy = false;
2115 break;
2116 }
2117 }
2118 }
2119
2120 if (!has_active) {
2121 /*
2122 * No active path in this pg, so this pg won't be used and
2123 * the current_pg will be changed at next mapping time.
2124 * We need to try mapping to determine it.
2125 */
2126 busy = false;
2127 }
2128
2129 return busy;
2130 }
2131
2132 /*-----------------------------------------------------------------
2133 * Module setup
2134 *---------------------------------------------------------------*/
2135 static struct target_type multipath_target = {
2136 .name = "multipath",
2137 .version = {1, 14, 0},
2138 .features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE |
2139 DM_TARGET_PASSES_INTEGRITY,
2140 .module = THIS_MODULE,
2141 .ctr = multipath_ctr,
2142 .dtr = multipath_dtr,
2143 .clone_and_map_rq = multipath_clone_and_map,
2144 .release_clone_rq = multipath_release_clone,
2145 .rq_end_io = multipath_end_io,
2146 .map = multipath_map_bio,
2147 .end_io = multipath_end_io_bio,
2148 .presuspend = multipath_presuspend,
2149 .postsuspend = multipath_postsuspend,
2150 .resume = multipath_resume,
2151 .status = multipath_status,
2152 .message = multipath_message,
2153 .prepare_ioctl = multipath_prepare_ioctl,
2154 .iterate_devices = multipath_iterate_devices,
2155 .busy = multipath_busy,
2156 };
2157
2158 static int __init dm_multipath_init(void)
2159 {
2160 int r;
2161
2162 kmultipathd = alloc_workqueue("kmpathd", WQ_MEM_RECLAIM, 0);
2163 if (!kmultipathd) {
2164 DMERR("failed to create workqueue kmpathd");
2165 r = -ENOMEM;
2166 goto bad_alloc_kmultipathd;
2167 }
2168
2169 /*
2170 * A separate workqueue is used to handle the device handlers
2171 * to avoid overloading existing workqueue. Overloading the
2172 * old workqueue would also create a bottleneck in the
2173 * path of the storage hardware device activation.
2174 */
2175 kmpath_handlerd = alloc_ordered_workqueue("kmpath_handlerd",
2176 WQ_MEM_RECLAIM);
2177 if (!kmpath_handlerd) {
2178 DMERR("failed to create workqueue kmpath_handlerd");
2179 r = -ENOMEM;
2180 goto bad_alloc_kmpath_handlerd;
2181 }
2182
2183 r = dm_register_target(&multipath_target);
2184 if (r < 0) {
2185 DMERR("request-based register failed %d", r);
2186 r = -EINVAL;
2187 goto bad_register_target;
2188 }
2189
2190 return 0;
2191
2192 bad_register_target:
2193 destroy_workqueue(kmpath_handlerd);
2194 bad_alloc_kmpath_handlerd:
2195 destroy_workqueue(kmultipathd);
2196 bad_alloc_kmultipathd:
2197 return r;
2198 }
2199
2200 static void __exit dm_multipath_exit(void)
2201 {
2202 destroy_workqueue(kmpath_handlerd);
2203 destroy_workqueue(kmultipathd);
2204
2205 dm_unregister_target(&multipath_target);
2206 }
2207
2208 module_init(dm_multipath_init);
2209 module_exit(dm_multipath_exit);
2210
2211 module_param_named(queue_if_no_path_timeout_secs,
2212 queue_if_no_path_timeout_secs, ulong, S_IRUGO | S_IWUSR);
2213 MODULE_PARM_DESC(queue_if_no_path_timeout_secs, "No available paths queue IO timeout in seconds");
2214
2215 MODULE_DESCRIPTION(DM_NAME " multipath target");
2216 MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
2217 MODULE_LICENSE("GPL");
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