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treewide: remove redundant IS_ERR() before error code check
[linux/fpc-iii.git] / drivers / md / dm-mpath.c
blob2bc18c9c3abcfc60e0763976704c878aea7fd13f
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 /*-----------------------------------------------
132 * Allocation routines
133 *-----------------------------------------------*/
134
135 static struct pgpath *alloc_pgpath(void)
136 {
137 struct pgpath *pgpath = kzalloc(sizeof(*pgpath), GFP_KERNEL);
138
139 if (!pgpath)
140 return NULL;
141
142 pgpath->is_active = true;
143
144 return pgpath;
145 }
146
147 static void free_pgpath(struct pgpath *pgpath)
148 {
149 kfree(pgpath);
150 }
151
152 static struct priority_group *alloc_priority_group(void)
153 {
154 struct priority_group *pg;
155
156 pg = kzalloc(sizeof(*pg), GFP_KERNEL);
157
158 if (pg)
159 INIT_LIST_HEAD(&pg->pgpaths);
160
161 return pg;
162 }
163
164 static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti)
165 {
166 struct pgpath *pgpath, *tmp;
167
168 list_for_each_entry_safe(pgpath, tmp, pgpaths, list) {
169 list_del(&pgpath->list);
170 dm_put_device(ti, pgpath->path.dev);
171 free_pgpath(pgpath);
172 }
173 }
174
175 static void free_priority_group(struct priority_group *pg,
176 struct dm_target *ti)
177 {
178 struct path_selector *ps = &pg->ps;
179
180 if (ps->type) {
181 ps->type->destroy(ps);
182 dm_put_path_selector(ps->type);
183 }
184
185 free_pgpaths(&pg->pgpaths, ti);
186 kfree(pg);
187 }
188
189 static struct multipath *alloc_multipath(struct dm_target *ti)
190 {
191 struct multipath *m;
192
193 m = kzalloc(sizeof(*m), GFP_KERNEL);
194 if (m) {
195 INIT_LIST_HEAD(&m->priority_groups);
196 spin_lock_init(&m->lock);
197 atomic_set(&m->nr_valid_paths, 0);
198 INIT_WORK(&m->trigger_event, trigger_event);
199 mutex_init(&m->work_mutex);
200
201 m->queue_mode = DM_TYPE_NONE;
202
203 m->ti = ti;
204 ti->private = m;
205
206 timer_setup(&m->nopath_timer, queue_if_no_path_timeout_work, 0);
207 }
208
209 return m;
210 }
211
212 static int alloc_multipath_stage2(struct dm_target *ti, struct multipath *m)
213 {
214 if (m->queue_mode == DM_TYPE_NONE) {
215 m->queue_mode = DM_TYPE_REQUEST_BASED;
216 } else if (m->queue_mode == DM_TYPE_BIO_BASED) {
217 INIT_WORK(&m->process_queued_bios, process_queued_bios);
218 /*
219 * bio-based doesn't support any direct scsi_dh management;
220 * it just discovers if a scsi_dh is attached.
221 */
222 set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags);
223 }
224
225 dm_table_set_type(ti->table, m->queue_mode);
226
227 /*
228 * Init fields that are only used when a scsi_dh is attached
229 * - must do this unconditionally (really doesn't hurt non-SCSI uses)
230 */
231 set_bit(MPATHF_QUEUE_IO, &m->flags);
232 atomic_set(&m->pg_init_in_progress, 0);
233 atomic_set(&m->pg_init_count, 0);
234 m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT;
235 init_waitqueue_head(&m->pg_init_wait);
236
237 return 0;
238 }
239
240 static void free_multipath(struct multipath *m)
241 {
242 struct priority_group *pg, *tmp;
243
244 list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) {
245 list_del(&pg->list);
246 free_priority_group(pg, m->ti);
247 }
248
249 kfree(m->hw_handler_name);
250 kfree(m->hw_handler_params);
251 mutex_destroy(&m->work_mutex);
252 kfree(m);
253 }
254
255 static struct dm_mpath_io *get_mpio(union map_info *info)
256 {
257 return info->ptr;
258 }
259
260 static size_t multipath_per_bio_data_size(void)
261 {
262 return sizeof(struct dm_mpath_io) + sizeof(struct dm_bio_details);
263 }
264
265 static struct dm_mpath_io *get_mpio_from_bio(struct bio *bio)
266 {
267 return dm_per_bio_data(bio, multipath_per_bio_data_size());
268 }
269
270 static struct dm_bio_details *get_bio_details_from_mpio(struct dm_mpath_io *mpio)
271 {
272 /* dm_bio_details is immediately after the dm_mpath_io in bio's per-bio-data */
273 void *bio_details = mpio + 1;
274 return bio_details;
275 }
276
277 static void multipath_init_per_bio_data(struct bio *bio, struct dm_mpath_io **mpio_p)
278 {
279 struct dm_mpath_io *mpio = get_mpio_from_bio(bio);
280 struct dm_bio_details *bio_details = get_bio_details_from_mpio(mpio);
281
282 mpio->nr_bytes = bio->bi_iter.bi_size;
283 mpio->pgpath = NULL;
284 *mpio_p = mpio;
285
286 dm_bio_record(bio_details, bio);
287 }
288
289 /*-----------------------------------------------
290 * Path selection
291 *-----------------------------------------------*/
292
293 static int __pg_init_all_paths(struct multipath *m)
294 {
295 struct pgpath *pgpath;
296 unsigned long pg_init_delay = 0;
297
298 lockdep_assert_held(&m->lock);
299
300 if (atomic_read(&m->pg_init_in_progress) || test_bit(MPATHF_PG_INIT_DISABLED, &m->flags))
301 return 0;
302
303 atomic_inc(&m->pg_init_count);
304 clear_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
305
306 /* Check here to reset pg_init_required */
307 if (!m->current_pg)
308 return 0;
309
310 if (test_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags))
311 pg_init_delay = msecs_to_jiffies(m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT ?
312 m->pg_init_delay_msecs : DM_PG_INIT_DELAY_MSECS);
313 list_for_each_entry(pgpath, &m->current_pg->pgpaths, list) {
314 /* Skip failed paths */
315 if (!pgpath->is_active)
316 continue;
317 if (queue_delayed_work(kmpath_handlerd, &pgpath->activate_path,
318 pg_init_delay))
319 atomic_inc(&m->pg_init_in_progress);
320 }
321 return atomic_read(&m->pg_init_in_progress);
322 }
323
324 static int pg_init_all_paths(struct multipath *m)
325 {
326 int ret;
327 unsigned long flags;
328
329 spin_lock_irqsave(&m->lock, flags);
330 ret = __pg_init_all_paths(m);
331 spin_unlock_irqrestore(&m->lock, flags);
332
333 return ret;
334 }
335
336 static void __switch_pg(struct multipath *m, struct priority_group *pg)
337 {
338 m->current_pg = pg;
339
340 /* Must we initialise the PG first, and queue I/O till it's ready? */
341 if (m->hw_handler_name) {
342 set_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
343 set_bit(MPATHF_QUEUE_IO, &m->flags);
344 } else {
345 clear_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
346 clear_bit(MPATHF_QUEUE_IO, &m->flags);
347 }
348
349 atomic_set(&m->pg_init_count, 0);
350 }
351
352 static struct pgpath *choose_path_in_pg(struct multipath *m,
353 struct priority_group *pg,
354 size_t nr_bytes)
355 {
356 unsigned long flags;
357 struct dm_path *path;
358 struct pgpath *pgpath;
359
360 path = pg->ps.type->select_path(&pg->ps, nr_bytes);
361 if (!path)
362 return ERR_PTR(-ENXIO);
363
364 pgpath = path_to_pgpath(path);
365
366 if (unlikely(READ_ONCE(m->current_pg) != pg)) {
367 /* Only update current_pgpath if pg changed */
368 spin_lock_irqsave(&m->lock, flags);
369 m->current_pgpath = pgpath;
370 __switch_pg(m, pg);
371 spin_unlock_irqrestore(&m->lock, flags);
372 }
373
374 return pgpath;
375 }
376
377 static struct pgpath *choose_pgpath(struct multipath *m, size_t nr_bytes)
378 {
379 unsigned long flags;
380 struct priority_group *pg;
381 struct pgpath *pgpath;
382 unsigned bypassed = 1;
383
384 if (!atomic_read(&m->nr_valid_paths)) {
385 clear_bit(MPATHF_QUEUE_IO, &m->flags);
386 goto failed;
387 }
388
389 /* Were we instructed to switch PG? */
390 if (READ_ONCE(m->next_pg)) {
391 spin_lock_irqsave(&m->lock, flags);
392 pg = m->next_pg;
393 if (!pg) {
394 spin_unlock_irqrestore(&m->lock, flags);
395 goto check_current_pg;
396 }
397 m->next_pg = NULL;
398 spin_unlock_irqrestore(&m->lock, flags);
399 pgpath = choose_path_in_pg(m, pg, nr_bytes);
400 if (!IS_ERR_OR_NULL(pgpath))
401 return pgpath;
402 }
403
404 /* Don't change PG until it has no remaining paths */
405 check_current_pg:
406 pg = READ_ONCE(m->current_pg);
407 if (pg) {
408 pgpath = choose_path_in_pg(m, pg, nr_bytes);
409 if (!IS_ERR_OR_NULL(pgpath))
410 return pgpath;
411 }
412
413 /*
414 * Loop through priority groups until we find a valid path.
415 * First time we skip PGs marked 'bypassed'.
416 * Second time we only try the ones we skipped, but set
417 * pg_init_delay_retry so we do not hammer controllers.
418 */
419 do {
420 list_for_each_entry(pg, &m->priority_groups, list) {
421 if (pg->bypassed == !!bypassed)
422 continue;
423 pgpath = choose_path_in_pg(m, pg, nr_bytes);
424 if (!IS_ERR_OR_NULL(pgpath)) {
425 if (!bypassed)
426 set_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
427 return pgpath;
428 }
429 }
430 } while (bypassed--);
431
432 failed:
433 spin_lock_irqsave(&m->lock, flags);
434 m->current_pgpath = NULL;
435 m->current_pg = NULL;
436 spin_unlock_irqrestore(&m->lock, flags);
437
438 return NULL;
439 }
440
441 /*
442 * dm_report_EIO() is a macro instead of a function to make pr_debug()
443 * report the function name and line number of the function from which
444 * it has been invoked.
445 */
446 #define dm_report_EIO(m) \
447 do { \
448 struct mapped_device *md = dm_table_get_md((m)->ti->table); \
449 \
450 pr_debug("%s: returning EIO; QIFNP = %d; SQIFNP = %d; DNFS = %d\n", \
451 dm_device_name(md), \
452 test_bit(MPATHF_QUEUE_IF_NO_PATH, &(m)->flags), \
453 test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &(m)->flags), \
454 dm_noflush_suspending((m)->ti)); \
455 } while (0)
456
457 /*
458 * Check whether bios must be queued in the device-mapper core rather
459 * than here in the target.
460 *
461 * If MPATHF_QUEUE_IF_NO_PATH and MPATHF_SAVED_QUEUE_IF_NO_PATH hold
462 * the same value then we are not between multipath_presuspend()
463 * and multipath_resume() calls and we have no need to check
464 * for the DMF_NOFLUSH_SUSPENDING flag.
465 */
466 static bool __must_push_back(struct multipath *m, unsigned long flags)
467 {
468 return ((test_bit(MPATHF_QUEUE_IF_NO_PATH, &flags) !=
469 test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &flags)) &&
470 dm_noflush_suspending(m->ti));
471 }
472
473 /*
474 * Following functions use READ_ONCE to get atomic access to
475 * all m->flags to avoid taking spinlock
476 */
477 static bool must_push_back_rq(struct multipath *m)
478 {
479 unsigned long flags = READ_ONCE(m->flags);
480 return test_bit(MPATHF_QUEUE_IF_NO_PATH, &flags) || __must_push_back(m, flags);
481 }
482
483 static bool must_push_back_bio(struct multipath *m)
484 {
485 unsigned long flags = READ_ONCE(m->flags);
486 return __must_push_back(m, flags);
487 }
488
489 /*
490 * Map cloned requests (request-based multipath)
491 */
492 static int multipath_clone_and_map(struct dm_target *ti, struct request *rq,
493 union map_info *map_context,
494 struct request **__clone)
495 {
496 struct multipath *m = ti->private;
497 size_t nr_bytes = blk_rq_bytes(rq);
498 struct pgpath *pgpath;
499 struct block_device *bdev;
500 struct dm_mpath_io *mpio = get_mpio(map_context);
501 struct request_queue *q;
502 struct request *clone;
503
504 /* Do we need to select a new pgpath? */
505 pgpath = READ_ONCE(m->current_pgpath);
506 if (!pgpath || !test_bit(MPATHF_QUEUE_IO, &m->flags))
507 pgpath = choose_pgpath(m, nr_bytes);
508
509 if (!pgpath) {
510 if (must_push_back_rq(m))
511 return DM_MAPIO_DELAY_REQUEUE;
512 dm_report_EIO(m); /* Failed */
513 return DM_MAPIO_KILL;
514 } else if (test_bit(MPATHF_QUEUE_IO, &m->flags) ||
515 test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags)) {
516 pg_init_all_paths(m);
517 return DM_MAPIO_DELAY_REQUEUE;
518 }
519
520 mpio->pgpath = pgpath;
521 mpio->nr_bytes = nr_bytes;
522
523 bdev = pgpath->path.dev->bdev;
524 q = bdev_get_queue(bdev);
525 clone = blk_get_request(q, rq->cmd_flags | REQ_NOMERGE,
526 BLK_MQ_REQ_NOWAIT);
527 if (IS_ERR(clone)) {
528 /* EBUSY, ENODEV or EWOULDBLOCK: requeue */
529 if (blk_queue_dying(q)) {
530 atomic_inc(&m->pg_init_in_progress);
531 activate_or_offline_path(pgpath);
532 return DM_MAPIO_DELAY_REQUEUE;
533 }
534
535 /*
536 * blk-mq's SCHED_RESTART can cover this requeue, so we
537 * needn't deal with it by DELAY_REQUEUE. More importantly,
538 * we have to return DM_MAPIO_REQUEUE so that blk-mq can
539 * get the queue busy feedback (via BLK_STS_RESOURCE),
540 * otherwise I/O merging can suffer.
541 */
542 return DM_MAPIO_REQUEUE;
543 }
544 clone->bio = clone->biotail = NULL;
545 clone->rq_disk = bdev->bd_disk;
546 clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
547 *__clone = clone;
548
549 if (pgpath->pg->ps.type->start_io)
550 pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
551 &pgpath->path,
552 nr_bytes);
553 return DM_MAPIO_REMAPPED;
554 }
555
556 static void multipath_release_clone(struct request *clone,
557 union map_info *map_context)
558 {
559 if (unlikely(map_context)) {
560 /*
561 * non-NULL map_context means caller is still map
562 * method; must undo multipath_clone_and_map()
563 */
564 struct dm_mpath_io *mpio = get_mpio(map_context);
565 struct pgpath *pgpath = mpio->pgpath;
566
567 if (pgpath && pgpath->pg->ps.type->end_io)
568 pgpath->pg->ps.type->end_io(&pgpath->pg->ps,
569 &pgpath->path,
570 mpio->nr_bytes);
571 }
572
573 blk_put_request(clone);
574 }
575
576 /*
577 * Map cloned bios (bio-based multipath)
578 */
579
580 static struct pgpath *__map_bio(struct multipath *m, struct bio *bio)
581 {
582 struct pgpath *pgpath;
583 unsigned long flags;
584 bool queue_io;
585
586 /* Do we need to select a new pgpath? */
587 pgpath = READ_ONCE(m->current_pgpath);
588 queue_io = test_bit(MPATHF_QUEUE_IO, &m->flags);
589 if (!pgpath || !queue_io)
590 pgpath = choose_pgpath(m, bio->bi_iter.bi_size);
591
592 if ((pgpath && queue_io) ||
593 (!pgpath && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))) {
594 /* Queue for the daemon to resubmit */
595 spin_lock_irqsave(&m->lock, flags);
596 bio_list_add(&m->queued_bios, bio);
597 spin_unlock_irqrestore(&m->lock, flags);
598
599 /* PG_INIT_REQUIRED cannot be set without QUEUE_IO */
600 if (queue_io || test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
601 pg_init_all_paths(m);
602 else if (!queue_io)
603 queue_work(kmultipathd, &m->process_queued_bios);
604
605 return ERR_PTR(-EAGAIN);
606 }
607
608 return pgpath;
609 }
610
611 static int __multipath_map_bio(struct multipath *m, struct bio *bio,
612 struct dm_mpath_io *mpio)
613 {
614 struct pgpath *pgpath = __map_bio(m, bio);
615
616 if (IS_ERR(pgpath))
617 return DM_MAPIO_SUBMITTED;
618
619 if (!pgpath) {
620 if (must_push_back_bio(m))
621 return DM_MAPIO_REQUEUE;
622 dm_report_EIO(m);
623 return DM_MAPIO_KILL;
624 }
625
626 mpio->pgpath = pgpath;
627
628 bio->bi_status = 0;
629 bio_set_dev(bio, pgpath->path.dev->bdev);
630 bio->bi_opf |= REQ_FAILFAST_TRANSPORT;
631
632 if (pgpath->pg->ps.type->start_io)
633 pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
634 &pgpath->path,
635 mpio->nr_bytes);
636 return DM_MAPIO_REMAPPED;
637 }
638
639 static int multipath_map_bio(struct dm_target *ti, struct bio *bio)
640 {
641 struct multipath *m = ti->private;
642 struct dm_mpath_io *mpio = NULL;
643
644 multipath_init_per_bio_data(bio, &mpio);
645 return __multipath_map_bio(m, bio, mpio);
646 }
647
648 static void process_queued_io_list(struct multipath *m)
649 {
650 if (m->queue_mode == DM_TYPE_REQUEST_BASED)
651 dm_mq_kick_requeue_list(dm_table_get_md(m->ti->table));
652 else if (m->queue_mode == DM_TYPE_BIO_BASED)
653 queue_work(kmultipathd, &m->process_queued_bios);
654 }
655
656 static void process_queued_bios(struct work_struct *work)
657 {
658 int r;
659 unsigned long flags;
660 struct bio *bio;
661 struct bio_list bios;
662 struct blk_plug plug;
663 struct multipath *m =
664 container_of(work, struct multipath, process_queued_bios);
665
666 bio_list_init(&bios);
667
668 spin_lock_irqsave(&m->lock, flags);
669
670 if (bio_list_empty(&m->queued_bios)) {
671 spin_unlock_irqrestore(&m->lock, flags);
672 return;
673 }
674
675 bio_list_merge(&bios, &m->queued_bios);
676 bio_list_init(&m->queued_bios);
677
678 spin_unlock_irqrestore(&m->lock, flags);
679
680 blk_start_plug(&plug);
681 while ((bio = bio_list_pop(&bios))) {
682 struct dm_mpath_io *mpio = get_mpio_from_bio(bio);
683 dm_bio_restore(get_bio_details_from_mpio(mpio), bio);
684 r = __multipath_map_bio(m, bio, mpio);
685 switch (r) {
686 case DM_MAPIO_KILL:
687 bio->bi_status = BLK_STS_IOERR;
688 bio_endio(bio);
689 break;
690 case DM_MAPIO_REQUEUE:
691 bio->bi_status = BLK_STS_DM_REQUEUE;
692 bio_endio(bio);
693 break;
694 case DM_MAPIO_REMAPPED:
695 generic_make_request(bio);
696 break;
697 case DM_MAPIO_SUBMITTED:
698 break;
699 default:
700 WARN_ONCE(true, "__multipath_map_bio() returned %d\n", r);
701 }
702 }
703 blk_finish_plug(&plug);
704 }
705
706 /*
707 * If we run out of usable paths, should we queue I/O or error it?
708 */
709 static int queue_if_no_path(struct multipath *m, bool queue_if_no_path,
710 bool save_old_value)
711 {
712 unsigned long flags;
713
714 spin_lock_irqsave(&m->lock, flags);
715 assign_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags,
716 (save_old_value && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) ||
717 (!save_old_value && queue_if_no_path));
718 assign_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags, queue_if_no_path);
719 spin_unlock_irqrestore(&m->lock, flags);
720
721 if (!queue_if_no_path) {
722 dm_table_run_md_queue_async(m->ti->table);
723 process_queued_io_list(m);
724 }
725
726 return 0;
727 }
728
729 /*
730 * If the queue_if_no_path timeout fires, turn off queue_if_no_path and
731 * process any queued I/O.
732 */
733 static void queue_if_no_path_timeout_work(struct timer_list *t)
734 {
735 struct multipath *m = from_timer(m, t, nopath_timer);
736 struct mapped_device *md = dm_table_get_md(m->ti->table);
737
738 DMWARN("queue_if_no_path timeout on %s, failing queued IO", dm_device_name(md));
739 queue_if_no_path(m, false, false);
740 }
741
742 /*
743 * Enable the queue_if_no_path timeout if necessary.
744 * Called with m->lock held.
745 */
746 static void enable_nopath_timeout(struct multipath *m)
747 {
748 unsigned long queue_if_no_path_timeout =
749 READ_ONCE(queue_if_no_path_timeout_secs) * HZ;
750
751 lockdep_assert_held(&m->lock);
752
753 if (queue_if_no_path_timeout > 0 &&
754 atomic_read(&m->nr_valid_paths) == 0 &&
755 test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
756 mod_timer(&m->nopath_timer,
757 jiffies + queue_if_no_path_timeout);
758 }
759 }
760
761 static void disable_nopath_timeout(struct multipath *m)
762 {
763 del_timer_sync(&m->nopath_timer);
764 }
765
766 /*
767 * An event is triggered whenever a path is taken out of use.
768 * Includes path failure and PG bypass.
769 */
770 static void trigger_event(struct work_struct *work)
771 {
772 struct multipath *m =
773 container_of(work, struct multipath, trigger_event);
774
775 dm_table_event(m->ti->table);
776 }
777
778 /*-----------------------------------------------------------------
779 * Constructor/argument parsing:
780 * <#multipath feature args> [<arg>]*
781 * <#hw_handler args> [hw_handler [<arg>]*]
782 * <#priority groups>
783 * <initial priority group>
784 * [<selector> <#selector args> [<arg>]*
785 * <#paths> <#per-path selector args>
786 * [<path> [<arg>]* ]+ ]+
787 *---------------------------------------------------------------*/
788 static int parse_path_selector(struct dm_arg_set *as, struct priority_group *pg,
789 struct dm_target *ti)
790 {
791 int r;
792 struct path_selector_type *pst;
793 unsigned ps_argc;
794
795 static const struct dm_arg _args[] = {
796 {0, 1024, "invalid number of path selector args"},
797 };
798
799 pst = dm_get_path_selector(dm_shift_arg(as));
800 if (!pst) {
801 ti->error = "unknown path selector type";
802 return -EINVAL;
803 }
804
805 r = dm_read_arg_group(_args, as, &ps_argc, &ti->error);
806 if (r) {
807 dm_put_path_selector(pst);
808 return -EINVAL;
809 }
810
811 r = pst->create(&pg->ps, ps_argc, as->argv);
812 if (r) {
813 dm_put_path_selector(pst);
814 ti->error = "path selector constructor failed";
815 return r;
816 }
817
818 pg->ps.type = pst;
819 dm_consume_args(as, ps_argc);
820
821 return 0;
822 }
823
824 static int setup_scsi_dh(struct block_device *bdev, struct multipath *m,
825 const char **attached_handler_name, char **error)
826 {
827 struct request_queue *q = bdev_get_queue(bdev);
828 int r;
829
830 if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags)) {
831 retain:
832 if (*attached_handler_name) {
833 /*
834 * Clear any hw_handler_params associated with a
835 * handler that isn't already attached.
836 */
837 if (m->hw_handler_name && strcmp(*attached_handler_name, m->hw_handler_name)) {
838 kfree(m->hw_handler_params);
839 m->hw_handler_params = NULL;
840 }
841
842 /*
843 * Reset hw_handler_name to match the attached handler
844 *
845 * NB. This modifies the table line to show the actual
846 * handler instead of the original table passed in.
847 */
848 kfree(m->hw_handler_name);
849 m->hw_handler_name = *attached_handler_name;
850 *attached_handler_name = NULL;
851 }
852 }
853
854 if (m->hw_handler_name) {
855 r = scsi_dh_attach(q, m->hw_handler_name);
856 if (r == -EBUSY) {
857 char b[BDEVNAME_SIZE];
858
859 printk(KERN_INFO "dm-mpath: retaining handler on device %s\n",
860 bdevname(bdev, b));
861 goto retain;
862 }
863 if (r < 0) {
864 *error = "error attaching hardware handler";
865 return r;
866 }
867
868 if (m->hw_handler_params) {
869 r = scsi_dh_set_params(q, m->hw_handler_params);
870 if (r < 0) {
871 *error = "unable to set hardware handler parameters";
872 return r;
873 }
874 }
875 }
876
877 return 0;
878 }
879
880 static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps,
881 struct dm_target *ti)
882 {
883 int r;
884 struct pgpath *p;
885 struct multipath *m = ti->private;
886 struct request_queue *q;
887 const char *attached_handler_name = NULL;
888
889 /* we need at least a path arg */
890 if (as->argc < 1) {
891 ti->error = "no device given";
892 return ERR_PTR(-EINVAL);
893 }
894
895 p = alloc_pgpath();
896 if (!p)
897 return ERR_PTR(-ENOMEM);
898
899 r = dm_get_device(ti, dm_shift_arg(as), dm_table_get_mode(ti->table),
900 &p->path.dev);
901 if (r) {
902 ti->error = "error getting device";
903 goto bad;
904 }
905
906 q = bdev_get_queue(p->path.dev->bdev);
907 attached_handler_name = scsi_dh_attached_handler_name(q, GFP_KERNEL);
908 if (attached_handler_name || m->hw_handler_name) {
909 INIT_DELAYED_WORK(&p->activate_path, activate_path_work);
910 r = setup_scsi_dh(p->path.dev->bdev, m, &attached_handler_name, &ti->error);
911 kfree(attached_handler_name);
912 if (r) {
913 dm_put_device(ti, p->path.dev);
914 goto bad;
915 }
916 }
917
918 r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
919 if (r) {
920 dm_put_device(ti, p->path.dev);
921 goto bad;
922 }
923
924 return p;
925 bad:
926 free_pgpath(p);
927 return ERR_PTR(r);
928 }
929
930 static struct priority_group *parse_priority_group(struct dm_arg_set *as,
931 struct multipath *m)
932 {
933 static const struct dm_arg _args[] = {
934 {1, 1024, "invalid number of paths"},
935 {0, 1024, "invalid number of selector args"}
936 };
937
938 int r;
939 unsigned i, nr_selector_args, nr_args;
940 struct priority_group *pg;
941 struct dm_target *ti = m->ti;
942
943 if (as->argc < 2) {
944 as->argc = 0;
945 ti->error = "not enough priority group arguments";
946 return ERR_PTR(-EINVAL);
947 }
948
949 pg = alloc_priority_group();
950 if (!pg) {
951 ti->error = "couldn't allocate priority group";
952 return ERR_PTR(-ENOMEM);
953 }
954 pg->m = m;
955
956 r = parse_path_selector(as, pg, ti);
957 if (r)
958 goto bad;
959
960 /*
961 * read the paths
962 */
963 r = dm_read_arg(_args, as, &pg->nr_pgpaths, &ti->error);
964 if (r)
965 goto bad;
966
967 r = dm_read_arg(_args + 1, as, &nr_selector_args, &ti->error);
968 if (r)
969 goto bad;
970
971 nr_args = 1 + nr_selector_args;
972 for (i = 0; i < pg->nr_pgpaths; i++) {
973 struct pgpath *pgpath;
974 struct dm_arg_set path_args;
975
976 if (as->argc < nr_args) {
977 ti->error = "not enough path parameters";
978 r = -EINVAL;
979 goto bad;
980 }
981
982 path_args.argc = nr_args;
983 path_args.argv = as->argv;
984
985 pgpath = parse_path(&path_args, &pg->ps, ti);
986 if (IS_ERR(pgpath)) {
987 r = PTR_ERR(pgpath);
988 goto bad;
989 }
990
991 pgpath->pg = pg;
992 list_add_tail(&pgpath->list, &pg->pgpaths);
993 dm_consume_args(as, nr_args);
994 }
995
996 return pg;
997
998 bad:
999 free_priority_group(pg, ti);
1000 return ERR_PTR(r);
1001 }
1002
1003 static int parse_hw_handler(struct dm_arg_set *as, struct multipath *m)
1004 {
1005 unsigned hw_argc;
1006 int ret;
1007 struct dm_target *ti = m->ti;
1008
1009 static const struct dm_arg _args[] = {
1010 {0, 1024, "invalid number of hardware handler args"},
1011 };
1012
1013 if (dm_read_arg_group(_args, as, &hw_argc, &ti->error))
1014 return -EINVAL;
1015
1016 if (!hw_argc)
1017 return 0;
1018
1019 if (m->queue_mode == DM_TYPE_BIO_BASED) {
1020 dm_consume_args(as, hw_argc);
1021 DMERR("bio-based multipath doesn't allow hardware handler args");
1022 return 0;
1023 }
1024
1025 m->hw_handler_name = kstrdup(dm_shift_arg(as), GFP_KERNEL);
1026 if (!m->hw_handler_name)
1027 return -EINVAL;
1028
1029 if (hw_argc > 1) {
1030 char *p;
1031 int i, j, len = 4;
1032
1033 for (i = 0; i <= hw_argc - 2; i++)
1034 len += strlen(as->argv[i]) + 1;
1035 p = m->hw_handler_params = kzalloc(len, GFP_KERNEL);
1036 if (!p) {
1037 ti->error = "memory allocation failed";
1038 ret = -ENOMEM;
1039 goto fail;
1040 }
1041 j = sprintf(p, "%d", hw_argc - 1);
1042 for (i = 0, p+=j+1; i <= hw_argc - 2; i++, p+=j+1)
1043 j = sprintf(p, "%s", as->argv[i]);
1044 }
1045 dm_consume_args(as, hw_argc - 1);
1046
1047 return 0;
1048 fail:
1049 kfree(m->hw_handler_name);
1050 m->hw_handler_name = NULL;
1051 return ret;
1052 }
1053
1054 static int parse_features(struct dm_arg_set *as, struct multipath *m)
1055 {
1056 int r;
1057 unsigned argc;
1058 struct dm_target *ti = m->ti;
1059 const char *arg_name;
1060
1061 static const struct dm_arg _args[] = {
1062 {0, 8, "invalid number of feature args"},
1063 {1, 50, "pg_init_retries must be between 1 and 50"},
1064 {0, 60000, "pg_init_delay_msecs must be between 0 and 60000"},
1065 };
1066
1067 r = dm_read_arg_group(_args, as, &argc, &ti->error);
1068 if (r)
1069 return -EINVAL;
1070
1071 if (!argc)
1072 return 0;
1073
1074 do {
1075 arg_name = dm_shift_arg(as);
1076 argc--;
1077
1078 if (!strcasecmp(arg_name, "queue_if_no_path")) {
1079 r = queue_if_no_path(m, true, false);
1080 continue;
1081 }
1082
1083 if (!strcasecmp(arg_name, "retain_attached_hw_handler")) {
1084 set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags);
1085 continue;
1086 }
1087
1088 if (!strcasecmp(arg_name, "pg_init_retries") &&
1089 (argc >= 1)) {
1090 r = dm_read_arg(_args + 1, as, &m->pg_init_retries, &ti->error);
1091 argc--;
1092 continue;
1093 }
1094
1095 if (!strcasecmp(arg_name, "pg_init_delay_msecs") &&
1096 (argc >= 1)) {
1097 r = dm_read_arg(_args + 2, as, &m->pg_init_delay_msecs, &ti->error);
1098 argc--;
1099 continue;
1100 }
1101
1102 if (!strcasecmp(arg_name, "queue_mode") &&
1103 (argc >= 1)) {
1104 const char *queue_mode_name = dm_shift_arg(as);
1105
1106 if (!strcasecmp(queue_mode_name, "bio"))
1107 m->queue_mode = DM_TYPE_BIO_BASED;
1108 else if (!strcasecmp(queue_mode_name, "rq") ||
1109 !strcasecmp(queue_mode_name, "mq"))
1110 m->queue_mode = DM_TYPE_REQUEST_BASED;
1111 else {
1112 ti->error = "Unknown 'queue_mode' requested";
1113 r = -EINVAL;
1114 }
1115 argc--;
1116 continue;
1117 }
1118
1119 ti->error = "Unrecognised multipath feature request";
1120 r = -EINVAL;
1121 } while (argc && !r);
1122
1123 return r;
1124 }
1125
1126 static int multipath_ctr(struct dm_target *ti, unsigned argc, char **argv)
1127 {
1128 /* target arguments */
1129 static const struct dm_arg _args[] = {
1130 {0, 1024, "invalid number of priority groups"},
1131 {0, 1024, "invalid initial priority group number"},
1132 };
1133
1134 int r;
1135 struct multipath *m;
1136 struct dm_arg_set as;
1137 unsigned pg_count = 0;
1138 unsigned next_pg_num;
1139 unsigned long flags;
1140
1141 as.argc = argc;
1142 as.argv = argv;
1143
1144 m = alloc_multipath(ti);
1145 if (!m) {
1146 ti->error = "can't allocate multipath";
1147 return -EINVAL;
1148 }
1149
1150 r = parse_features(&as, m);
1151 if (r)
1152 goto bad;
1153
1154 r = alloc_multipath_stage2(ti, m);
1155 if (r)
1156 goto bad;
1157
1158 r = parse_hw_handler(&as, m);
1159 if (r)
1160 goto bad;
1161
1162 r = dm_read_arg(_args, &as, &m->nr_priority_groups, &ti->error);
1163 if (r)
1164 goto bad;
1165
1166 r = dm_read_arg(_args + 1, &as, &next_pg_num, &ti->error);
1167 if (r)
1168 goto bad;
1169
1170 if ((!m->nr_priority_groups && next_pg_num) ||
1171 (m->nr_priority_groups && !next_pg_num)) {
1172 ti->error = "invalid initial priority group";
1173 r = -EINVAL;
1174 goto bad;
1175 }
1176
1177 /* parse the priority groups */
1178 while (as.argc) {
1179 struct priority_group *pg;
1180 unsigned nr_valid_paths = atomic_read(&m->nr_valid_paths);
1181
1182 pg = parse_priority_group(&as, m);
1183 if (IS_ERR(pg)) {
1184 r = PTR_ERR(pg);
1185 goto bad;
1186 }
1187
1188 nr_valid_paths += pg->nr_pgpaths;
1189 atomic_set(&m->nr_valid_paths, nr_valid_paths);
1190
1191 list_add_tail(&pg->list, &m->priority_groups);
1192 pg_count++;
1193 pg->pg_num = pg_count;
1194 if (!--next_pg_num)
1195 m->next_pg = pg;
1196 }
1197
1198 if (pg_count != m->nr_priority_groups) {
1199 ti->error = "priority group count mismatch";
1200 r = -EINVAL;
1201 goto bad;
1202 }
1203
1204 spin_lock_irqsave(&m->lock, flags);
1205 enable_nopath_timeout(m);
1206 spin_unlock_irqrestore(&m->lock, flags);
1207
1208 ti->num_flush_bios = 1;
1209 ti->num_discard_bios = 1;
1210 ti->num_write_same_bios = 1;
1211 ti->num_write_zeroes_bios = 1;
1212 if (m->queue_mode == DM_TYPE_BIO_BASED)
1213 ti->per_io_data_size = multipath_per_bio_data_size();
1214 else
1215 ti->per_io_data_size = sizeof(struct dm_mpath_io);
1216
1217 return 0;
1218
1219 bad:
1220 free_multipath(m);
1221 return r;
1222 }
1223
1224 static void multipath_wait_for_pg_init_completion(struct multipath *m)
1225 {
1226 DEFINE_WAIT(wait);
1227
1228 while (1) {
1229 prepare_to_wait(&m->pg_init_wait, &wait, TASK_UNINTERRUPTIBLE);
1230
1231 if (!atomic_read(&m->pg_init_in_progress))
1232 break;
1233
1234 io_schedule();
1235 }
1236 finish_wait(&m->pg_init_wait, &wait);
1237 }
1238
1239 static void flush_multipath_work(struct multipath *m)
1240 {
1241 if (m->hw_handler_name) {
1242 set_bit(MPATHF_PG_INIT_DISABLED, &m->flags);
1243 smp_mb__after_atomic();
1244
1245 if (atomic_read(&m->pg_init_in_progress))
1246 flush_workqueue(kmpath_handlerd);
1247 multipath_wait_for_pg_init_completion(m);
1248
1249 clear_bit(MPATHF_PG_INIT_DISABLED, &m->flags);
1250 smp_mb__after_atomic();
1251 }
1252
1253 if (m->queue_mode == DM_TYPE_BIO_BASED)
1254 flush_work(&m->process_queued_bios);
1255 flush_work(&m->trigger_event);
1256 }
1257
1258 static void multipath_dtr(struct dm_target *ti)
1259 {
1260 struct multipath *m = ti->private;
1261
1262 disable_nopath_timeout(m);
1263 flush_multipath_work(m);
1264 free_multipath(m);
1265 }
1266
1267 /*
1268 * Take a path out of use.
1269 */
1270 static int fail_path(struct pgpath *pgpath)
1271 {
1272 unsigned long flags;
1273 struct multipath *m = pgpath->pg->m;
1274
1275 spin_lock_irqsave(&m->lock, flags);
1276
1277 if (!pgpath->is_active)
1278 goto out;
1279
1280 DMWARN("Failing path %s.", pgpath->path.dev->name);
1281
1282 pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
1283 pgpath->is_active = false;
1284 pgpath->fail_count++;
1285
1286 atomic_dec(&m->nr_valid_paths);
1287
1288 if (pgpath == m->current_pgpath)
1289 m->current_pgpath = NULL;
1290
1291 dm_path_uevent(DM_UEVENT_PATH_FAILED, m->ti,
1292 pgpath->path.dev->name, atomic_read(&m->nr_valid_paths));
1293
1294 schedule_work(&m->trigger_event);
1295
1296 enable_nopath_timeout(m);
1297
1298 out:
1299 spin_unlock_irqrestore(&m->lock, flags);
1300
1301 return 0;
1302 }
1303
1304 /*
1305 * Reinstate a previously-failed path
1306 */
1307 static int reinstate_path(struct pgpath *pgpath)
1308 {
1309 int r = 0, run_queue = 0;
1310 unsigned long flags;
1311 struct multipath *m = pgpath->pg->m;
1312 unsigned nr_valid_paths;
1313
1314 spin_lock_irqsave(&m->lock, flags);
1315
1316 if (pgpath->is_active)
1317 goto out;
1318
1319 DMWARN("Reinstating path %s.", pgpath->path.dev->name);
1320
1321 r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
1322 if (r)
1323 goto out;
1324
1325 pgpath->is_active = true;
1326
1327 nr_valid_paths = atomic_inc_return(&m->nr_valid_paths);
1328 if (nr_valid_paths == 1) {
1329 m->current_pgpath = NULL;
1330 run_queue = 1;
1331 } else if (m->hw_handler_name && (m->current_pg == pgpath->pg)) {
1332 if (queue_work(kmpath_handlerd, &pgpath->activate_path.work))
1333 atomic_inc(&m->pg_init_in_progress);
1334 }
1335
1336 dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti,
1337 pgpath->path.dev->name, nr_valid_paths);
1338
1339 schedule_work(&m->trigger_event);
1340
1341 out:
1342 spin_unlock_irqrestore(&m->lock, flags);
1343 if (run_queue) {
1344 dm_table_run_md_queue_async(m->ti->table);
1345 process_queued_io_list(m);
1346 }
1347
1348 if (pgpath->is_active)
1349 disable_nopath_timeout(m);
1350
1351 return r;
1352 }
1353
1354 /*
1355 * Fail or reinstate all paths that match the provided struct dm_dev.
1356 */
1357 static int action_dev(struct multipath *m, struct dm_dev *dev,
1358 action_fn action)
1359 {
1360 int r = -EINVAL;
1361 struct pgpath *pgpath;
1362 struct priority_group *pg;
1363
1364 list_for_each_entry(pg, &m->priority_groups, list) {
1365 list_for_each_entry(pgpath, &pg->pgpaths, list) {
1366 if (pgpath->path.dev == dev)
1367 r = action(pgpath);
1368 }
1369 }
1370
1371 return r;
1372 }
1373
1374 /*
1375 * Temporarily try to avoid having to use the specified PG
1376 */
1377 static void bypass_pg(struct multipath *m, struct priority_group *pg,
1378 bool bypassed)
1379 {
1380 unsigned long flags;
1381
1382 spin_lock_irqsave(&m->lock, flags);
1383
1384 pg->bypassed = bypassed;
1385 m->current_pgpath = NULL;
1386 m->current_pg = NULL;
1387
1388 spin_unlock_irqrestore(&m->lock, flags);
1389
1390 schedule_work(&m->trigger_event);
1391 }
1392
1393 /*
1394 * Switch to using the specified PG from the next I/O that gets mapped
1395 */
1396 static int switch_pg_num(struct multipath *m, const char *pgstr)
1397 {
1398 struct priority_group *pg;
1399 unsigned pgnum;
1400 unsigned long flags;
1401 char dummy;
1402
1403 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1404 !m->nr_priority_groups || (pgnum > m->nr_priority_groups)) {
1405 DMWARN("invalid PG number supplied to switch_pg_num");
1406 return -EINVAL;
1407 }
1408
1409 spin_lock_irqsave(&m->lock, flags);
1410 list_for_each_entry(pg, &m->priority_groups, list) {
1411 pg->bypassed = false;
1412 if (--pgnum)
1413 continue;
1414
1415 m->current_pgpath = NULL;
1416 m->current_pg = NULL;
1417 m->next_pg = pg;
1418 }
1419 spin_unlock_irqrestore(&m->lock, flags);
1420
1421 schedule_work(&m->trigger_event);
1422 return 0;
1423 }
1424
1425 /*
1426 * Set/clear bypassed status of a PG.
1427 * PGs are numbered upwards from 1 in the order they were declared.
1428 */
1429 static int bypass_pg_num(struct multipath *m, const char *pgstr, bool bypassed)
1430 {
1431 struct priority_group *pg;
1432 unsigned pgnum;
1433 char dummy;
1434
1435 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1436 !m->nr_priority_groups || (pgnum > m->nr_priority_groups)) {
1437 DMWARN("invalid PG number supplied to bypass_pg");
1438 return -EINVAL;
1439 }
1440
1441 list_for_each_entry(pg, &m->priority_groups, list) {
1442 if (!--pgnum)
1443 break;
1444 }
1445
1446 bypass_pg(m, pg, bypassed);
1447 return 0;
1448 }
1449
1450 /*
1451 * Should we retry pg_init immediately?
1452 */
1453 static bool pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath)
1454 {
1455 unsigned long flags;
1456 bool limit_reached = false;
1457
1458 spin_lock_irqsave(&m->lock, flags);
1459
1460 if (atomic_read(&m->pg_init_count) <= m->pg_init_retries &&
1461 !test_bit(MPATHF_PG_INIT_DISABLED, &m->flags))
1462 set_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
1463 else
1464 limit_reached = true;
1465
1466 spin_unlock_irqrestore(&m->lock, flags);
1467
1468 return limit_reached;
1469 }
1470
1471 static void pg_init_done(void *data, int errors)
1472 {
1473 struct pgpath *pgpath = data;
1474 struct priority_group *pg = pgpath->pg;
1475 struct multipath *m = pg->m;
1476 unsigned long flags;
1477 bool delay_retry = false;
1478
1479 /* device or driver problems */
1480 switch (errors) {
1481 case SCSI_DH_OK:
1482 break;
1483 case SCSI_DH_NOSYS:
1484 if (!m->hw_handler_name) {
1485 errors = 0;
1486 break;
1487 }
1488 DMERR("Could not failover the device: Handler scsi_dh_%s "
1489 "Error %d.", m->hw_handler_name, errors);
1490 /*
1491 * Fail path for now, so we do not ping pong
1492 */
1493 fail_path(pgpath);
1494 break;
1495 case SCSI_DH_DEV_TEMP_BUSY:
1496 /*
1497 * Probably doing something like FW upgrade on the
1498 * controller so try the other pg.
1499 */
1500 bypass_pg(m, pg, true);
1501 break;
1502 case SCSI_DH_RETRY:
1503 /* Wait before retrying. */
1504 delay_retry = true;
1505 /* fall through */
1506 case SCSI_DH_IMM_RETRY:
1507 case SCSI_DH_RES_TEMP_UNAVAIL:
1508 if (pg_init_limit_reached(m, pgpath))
1509 fail_path(pgpath);
1510 errors = 0;
1511 break;
1512 case SCSI_DH_DEV_OFFLINED:
1513 default:
1514 /*
1515 * We probably do not want to fail the path for a device
1516 * error, but this is what the old dm did. In future
1517 * patches we can do more advanced handling.
1518 */
1519 fail_path(pgpath);
1520 }
1521
1522 spin_lock_irqsave(&m->lock, flags);
1523 if (errors) {
1524 if (pgpath == m->current_pgpath) {
1525 DMERR("Could not failover device. Error %d.", errors);
1526 m->current_pgpath = NULL;
1527 m->current_pg = NULL;
1528 }
1529 } else if (!test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
1530 pg->bypassed = false;
1531
1532 if (atomic_dec_return(&m->pg_init_in_progress) > 0)
1533 /* Activations of other paths are still on going */
1534 goto out;
1535
1536 if (test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags)) {
1537 if (delay_retry)
1538 set_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
1539 else
1540 clear_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
1541
1542 if (__pg_init_all_paths(m))
1543 goto out;
1544 }
1545 clear_bit(MPATHF_QUEUE_IO, &m->flags);
1546
1547 process_queued_io_list(m);
1548
1549 /*
1550 * Wake up any thread waiting to suspend.
1551 */
1552 wake_up(&m->pg_init_wait);
1553
1554 out:
1555 spin_unlock_irqrestore(&m->lock, flags);
1556 }
1557
1558 static void activate_or_offline_path(struct pgpath *pgpath)
1559 {
1560 struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
1561
1562 if (pgpath->is_active && !blk_queue_dying(q))
1563 scsi_dh_activate(q, pg_init_done, pgpath);
1564 else
1565 pg_init_done(pgpath, SCSI_DH_DEV_OFFLINED);
1566 }
1567
1568 static void activate_path_work(struct work_struct *work)
1569 {
1570 struct pgpath *pgpath =
1571 container_of(work, struct pgpath, activate_path.work);
1572
1573 activate_or_offline_path(pgpath);
1574 }
1575
1576 static int multipath_end_io(struct dm_target *ti, struct request *clone,
1577 blk_status_t error, union map_info *map_context)
1578 {
1579 struct dm_mpath_io *mpio = get_mpio(map_context);
1580 struct pgpath *pgpath = mpio->pgpath;
1581 int r = DM_ENDIO_DONE;
1582
1583 /*
1584 * We don't queue any clone request inside the multipath target
1585 * during end I/O handling, since those clone requests don't have
1586 * bio clones. If we queue them inside the multipath target,
1587 * we need to make bio clones, that requires memory allocation.
1588 * (See drivers/md/dm-rq.c:end_clone_bio() about why the clone requests
1589 * don't have bio clones.)
1590 * Instead of queueing the clone request here, we queue the original
1591 * request into dm core, which will remake a clone request and
1592 * clone bios for it and resubmit it later.
1593 */
1594 if (error && blk_path_error(error)) {
1595 struct multipath *m = ti->private;
1596
1597 if (error == BLK_STS_RESOURCE)
1598 r = DM_ENDIO_DELAY_REQUEUE;
1599 else
1600 r = DM_ENDIO_REQUEUE;
1601
1602 if (pgpath)
1603 fail_path(pgpath);
1604
1605 if (atomic_read(&m->nr_valid_paths) == 0 &&
1606 !must_push_back_rq(m)) {
1607 if (error == BLK_STS_IOERR)
1608 dm_report_EIO(m);
1609 /* complete with the original error */
1610 r = DM_ENDIO_DONE;
1611 }
1612 }
1613
1614 if (pgpath) {
1615 struct path_selector *ps = &pgpath->pg->ps;
1616
1617 if (ps->type->end_io)
1618 ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
1619 }
1620
1621 return r;
1622 }
1623
1624 static int multipath_end_io_bio(struct dm_target *ti, struct bio *clone,
1625 blk_status_t *error)
1626 {
1627 struct multipath *m = ti->private;
1628 struct dm_mpath_io *mpio = get_mpio_from_bio(clone);
1629 struct pgpath *pgpath = mpio->pgpath;
1630 unsigned long flags;
1631 int r = DM_ENDIO_DONE;
1632
1633 if (!*error || !blk_path_error(*error))
1634 goto done;
1635
1636 if (pgpath)
1637 fail_path(pgpath);
1638
1639 if (atomic_read(&m->nr_valid_paths) == 0 &&
1640 !test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
1641 if (must_push_back_bio(m)) {
1642 r = DM_ENDIO_REQUEUE;
1643 } else {
1644 dm_report_EIO(m);
1645 *error = BLK_STS_IOERR;
1646 }
1647 goto done;
1648 }
1649
1650 spin_lock_irqsave(&m->lock, flags);
1651 bio_list_add(&m->queued_bios, clone);
1652 spin_unlock_irqrestore(&m->lock, flags);
1653 if (!test_bit(MPATHF_QUEUE_IO, &m->flags))
1654 queue_work(kmultipathd, &m->process_queued_bios);
1655
1656 r = DM_ENDIO_INCOMPLETE;
1657 done:
1658 if (pgpath) {
1659 struct path_selector *ps = &pgpath->pg->ps;
1660
1661 if (ps->type->end_io)
1662 ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
1663 }
1664
1665 return r;
1666 }
1667
1668 /*
1669 * Suspend can't complete until all the I/O is processed so if
1670 * the last path fails we must error any remaining I/O.
1671 * Note that if the freeze_bdev fails while suspending, the
1672 * queue_if_no_path state is lost - userspace should reset it.
1673 */
1674 static void multipath_presuspend(struct dm_target *ti)
1675 {
1676 struct multipath *m = ti->private;
1677
1678 queue_if_no_path(m, false, true);
1679 }
1680
1681 static void multipath_postsuspend(struct dm_target *ti)
1682 {
1683 struct multipath *m = ti->private;
1684
1685 mutex_lock(&m->work_mutex);
1686 flush_multipath_work(m);
1687 mutex_unlock(&m->work_mutex);
1688 }
1689
1690 /*
1691 * Restore the queue_if_no_path setting.
1692 */
1693 static void multipath_resume(struct dm_target *ti)
1694 {
1695 struct multipath *m = ti->private;
1696 unsigned long flags;
1697
1698 spin_lock_irqsave(&m->lock, flags);
1699 assign_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags,
1700 test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags));
1701 spin_unlock_irqrestore(&m->lock, flags);
1702 }
1703
1704 /*
1705 * Info output has the following format:
1706 * num_multipath_feature_args [multipath_feature_args]*
1707 * num_handler_status_args [handler_status_args]*
1708 * num_groups init_group_number
1709 * [A|D|E num_ps_status_args [ps_status_args]*
1710 * num_paths num_selector_args
1711 * [path_dev A|F fail_count [selector_args]* ]+ ]+
1712 *
1713 * Table output has the following format (identical to the constructor string):
1714 * num_feature_args [features_args]*
1715 * num_handler_args hw_handler [hw_handler_args]*
1716 * num_groups init_group_number
1717 * [priority selector-name num_ps_args [ps_args]*
1718 * num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
1719 */
1720 static void multipath_status(struct dm_target *ti, status_type_t type,
1721 unsigned status_flags, char *result, unsigned maxlen)
1722 {
1723 int sz = 0;
1724 unsigned long flags;
1725 struct multipath *m = ti->private;
1726 struct priority_group *pg;
1727 struct pgpath *p;
1728 unsigned pg_num;
1729 char state;
1730
1731 spin_lock_irqsave(&m->lock, flags);
1732
1733 /* Features */
1734 if (type == STATUSTYPE_INFO)
1735 DMEMIT("2 %u %u ", test_bit(MPATHF_QUEUE_IO, &m->flags),
1736 atomic_read(&m->pg_init_count));
1737 else {
1738 DMEMIT("%u ", test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) +
1739 (m->pg_init_retries > 0) * 2 +
1740 (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT) * 2 +
1741 test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags) +
1742 (m->queue_mode != DM_TYPE_REQUEST_BASED) * 2);
1743
1744 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
1745 DMEMIT("queue_if_no_path ");
1746 if (m->pg_init_retries)
1747 DMEMIT("pg_init_retries %u ", m->pg_init_retries);
1748 if (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT)
1749 DMEMIT("pg_init_delay_msecs %u ", m->pg_init_delay_msecs);
1750 if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags))
1751 DMEMIT("retain_attached_hw_handler ");
1752 if (m->queue_mode != DM_TYPE_REQUEST_BASED) {
1753 switch(m->queue_mode) {
1754 case DM_TYPE_BIO_BASED:
1755 DMEMIT("queue_mode bio ");
1756 break;
1757 default:
1758 WARN_ON_ONCE(true);
1759 break;
1760 }
1761 }
1762 }
1763
1764 if (!m->hw_handler_name || type == STATUSTYPE_INFO)
1765 DMEMIT("0 ");
1766 else
1767 DMEMIT("1 %s ", m->hw_handler_name);
1768
1769 DMEMIT("%u ", m->nr_priority_groups);
1770
1771 if (m->next_pg)
1772 pg_num = m->next_pg->pg_num;
1773 else if (m->current_pg)
1774 pg_num = m->current_pg->pg_num;
1775 else
1776 pg_num = (m->nr_priority_groups ? 1 : 0);
1777
1778 DMEMIT("%u ", pg_num);
1779
1780 switch (type) {
1781 case STATUSTYPE_INFO:
1782 list_for_each_entry(pg, &m->priority_groups, list) {
1783 if (pg->bypassed)
1784 state = 'D'; /* Disabled */
1785 else if (pg == m->current_pg)
1786 state = 'A'; /* Currently Active */
1787 else
1788 state = 'E'; /* Enabled */
1789
1790 DMEMIT("%c ", state);
1791
1792 if (pg->ps.type->status)
1793 sz += pg->ps.type->status(&pg->ps, NULL, type,
1794 result + sz,
1795 maxlen - sz);
1796 else
1797 DMEMIT("0 ");
1798
1799 DMEMIT("%u %u ", pg->nr_pgpaths,
1800 pg->ps.type->info_args);
1801
1802 list_for_each_entry(p, &pg->pgpaths, list) {
1803 DMEMIT("%s %s %u ", p->path.dev->name,
1804 p->is_active ? "A" : "F",
1805 p->fail_count);
1806 if (pg->ps.type->status)
1807 sz += pg->ps.type->status(&pg->ps,
1808 &p->path, type, result + sz,
1809 maxlen - sz);
1810 }
1811 }
1812 break;
1813
1814 case STATUSTYPE_TABLE:
1815 list_for_each_entry(pg, &m->priority_groups, list) {
1816 DMEMIT("%s ", pg->ps.type->name);
1817
1818 if (pg->ps.type->status)
1819 sz += pg->ps.type->status(&pg->ps, NULL, type,
1820 result + sz,
1821 maxlen - sz);
1822 else
1823 DMEMIT("0 ");
1824
1825 DMEMIT("%u %u ", pg->nr_pgpaths,
1826 pg->ps.type->table_args);
1827
1828 list_for_each_entry(p, &pg->pgpaths, list) {
1829 DMEMIT("%s ", p->path.dev->name);
1830 if (pg->ps.type->status)
1831 sz += pg->ps.type->status(&pg->ps,
1832 &p->path, type, result + sz,
1833 maxlen - sz);
1834 }
1835 }
1836 break;
1837 }
1838
1839 spin_unlock_irqrestore(&m->lock, flags);
1840 }
1841
1842 static int multipath_message(struct dm_target *ti, unsigned argc, char **argv,
1843 char *result, unsigned maxlen)
1844 {
1845 int r = -EINVAL;
1846 struct dm_dev *dev;
1847 struct multipath *m = ti->private;
1848 action_fn action;
1849 unsigned long flags;
1850
1851 mutex_lock(&m->work_mutex);
1852
1853 if (dm_suspended(ti)) {
1854 r = -EBUSY;
1855 goto out;
1856 }
1857
1858 if (argc == 1) {
1859 if (!strcasecmp(argv[0], "queue_if_no_path")) {
1860 r = queue_if_no_path(m, true, false);
1861 spin_lock_irqsave(&m->lock, flags);
1862 enable_nopath_timeout(m);
1863 spin_unlock_irqrestore(&m->lock, flags);
1864 goto out;
1865 } else if (!strcasecmp(argv[0], "fail_if_no_path")) {
1866 r = queue_if_no_path(m, false, false);
1867 disable_nopath_timeout(m);
1868 goto out;
1869 }
1870 }
1871
1872 if (argc != 2) {
1873 DMWARN("Invalid multipath message arguments. Expected 2 arguments, got %d.", argc);
1874 goto out;
1875 }
1876
1877 if (!strcasecmp(argv[0], "disable_group")) {
1878 r = bypass_pg_num(m, argv[1], true);
1879 goto out;
1880 } else if (!strcasecmp(argv[0], "enable_group")) {
1881 r = bypass_pg_num(m, argv[1], false);
1882 goto out;
1883 } else if (!strcasecmp(argv[0], "switch_group")) {
1884 r = switch_pg_num(m, argv[1]);
1885 goto out;
1886 } else if (!strcasecmp(argv[0], "reinstate_path"))
1887 action = reinstate_path;
1888 else if (!strcasecmp(argv[0], "fail_path"))
1889 action = fail_path;
1890 else {
1891 DMWARN("Unrecognised multipath message received: %s", argv[0]);
1892 goto out;
1893 }
1894
1895 r = dm_get_device(ti, argv[1], dm_table_get_mode(ti->table), &dev);
1896 if (r) {
1897 DMWARN("message: error getting device %s",
1898 argv[1]);
1899 goto out;
1900 }
1901
1902 r = action_dev(m, dev, action);
1903
1904 dm_put_device(ti, dev);
1905
1906 out:
1907 mutex_unlock(&m->work_mutex);
1908 return r;
1909 }
1910
1911 static int multipath_prepare_ioctl(struct dm_target *ti,
1912 struct block_device **bdev)
1913 {
1914 struct multipath *m = ti->private;
1915 struct pgpath *current_pgpath;
1916 int r;
1917
1918 current_pgpath = READ_ONCE(m->current_pgpath);
1919 if (!current_pgpath)
1920 current_pgpath = choose_pgpath(m, 0);
1921
1922 if (current_pgpath) {
1923 if (!test_bit(MPATHF_QUEUE_IO, &m->flags)) {
1924 *bdev = current_pgpath->path.dev->bdev;
1925 r = 0;
1926 } else {
1927 /* pg_init has not started or completed */
1928 r = -ENOTCONN;
1929 }
1930 } else {
1931 /* No path is available */
1932 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
1933 r = -ENOTCONN;
1934 else
1935 r = -EIO;
1936 }
1937
1938 if (r == -ENOTCONN) {
1939 if (!READ_ONCE(m->current_pg)) {
1940 /* Path status changed, redo selection */
1941 (void) choose_pgpath(m, 0);
1942 }
1943 if (test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
1944 pg_init_all_paths(m);
1945 dm_table_run_md_queue_async(m->ti->table);
1946 process_queued_io_list(m);
1947 }
1948
1949 /*
1950 * Only pass ioctls through if the device sizes match exactly.
1951 */
1952 if (!r && ti->len != i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT)
1953 return 1;
1954 return r;
1955 }
1956
1957 static int multipath_iterate_devices(struct dm_target *ti,
1958 iterate_devices_callout_fn fn, void *data)
1959 {
1960 struct multipath *m = ti->private;
1961 struct priority_group *pg;
1962 struct pgpath *p;
1963 int ret = 0;
1964
1965 list_for_each_entry(pg, &m->priority_groups, list) {
1966 list_for_each_entry(p, &pg->pgpaths, list) {
1967 ret = fn(ti, p->path.dev, ti->begin, ti->len, data);
1968 if (ret)
1969 goto out;
1970 }
1971 }
1972
1973 out:
1974 return ret;
1975 }
1976
1977 static int pgpath_busy(struct pgpath *pgpath)
1978 {
1979 struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
1980
1981 return blk_lld_busy(q);
1982 }
1983
1984 /*
1985 * We return "busy", only when we can map I/Os but underlying devices
1986 * are busy (so even if we map I/Os now, the I/Os will wait on
1987 * the underlying queue).
1988 * In other words, if we want to kill I/Os or queue them inside us
1989 * due to map unavailability, we don't return "busy". Otherwise,
1990 * dm core won't give us the I/Os and we can't do what we want.
1991 */
1992 static int multipath_busy(struct dm_target *ti)
1993 {
1994 bool busy = false, has_active = false;
1995 struct multipath *m = ti->private;
1996 struct priority_group *pg, *next_pg;
1997 struct pgpath *pgpath;
1998
1999 /* pg_init in progress */
2000 if (atomic_read(&m->pg_init_in_progress))
2001 return true;
2002
2003 /* no paths available, for blk-mq: rely on IO mapping to delay requeue */
2004 if (!atomic_read(&m->nr_valid_paths) && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
2005 return (m->queue_mode != DM_TYPE_REQUEST_BASED);
2006
2007 /* Guess which priority_group will be used at next mapping time */
2008 pg = READ_ONCE(m->current_pg);
2009 next_pg = READ_ONCE(m->next_pg);
2010 if (unlikely(!READ_ONCE(m->current_pgpath) && next_pg))
2011 pg = next_pg;
2012
2013 if (!pg) {
2014 /*
2015 * We don't know which pg will be used at next mapping time.
2016 * We don't call choose_pgpath() here to avoid to trigger
2017 * pg_init just by busy checking.
2018 * So we don't know whether underlying devices we will be using
2019 * at next mapping time are busy or not. Just try mapping.
2020 */
2021 return busy;
2022 }
2023
2024 /*
2025 * If there is one non-busy active path at least, the path selector
2026 * will be able to select it. So we consider such a pg as not busy.
2027 */
2028 busy = true;
2029 list_for_each_entry(pgpath, &pg->pgpaths, list) {
2030 if (pgpath->is_active) {
2031 has_active = true;
2032 if (!pgpath_busy(pgpath)) {
2033 busy = false;
2034 break;
2035 }
2036 }
2037 }
2038
2039 if (!has_active) {
2040 /*
2041 * No active path in this pg, so this pg won't be used and
2042 * the current_pg will be changed at next mapping time.
2043 * We need to try mapping to determine it.
2044 */
2045 busy = false;
2046 }
2047
2048 return busy;
2049 }
2050
2051 /*-----------------------------------------------------------------
2052 * Module setup
2053 *---------------------------------------------------------------*/
2054 static struct target_type multipath_target = {
2055 .name = "multipath",
2056 .version = {1, 13, 0},
2057 .features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE |
2058 DM_TARGET_PASSES_INTEGRITY,
2059 .module = THIS_MODULE,
2060 .ctr = multipath_ctr,
2061 .dtr = multipath_dtr,
2062 .clone_and_map_rq = multipath_clone_and_map,
2063 .release_clone_rq = multipath_release_clone,
2064 .rq_end_io = multipath_end_io,
2065 .map = multipath_map_bio,
2066 .end_io = multipath_end_io_bio,
2067 .presuspend = multipath_presuspend,
2068 .postsuspend = multipath_postsuspend,
2069 .resume = multipath_resume,
2070 .status = multipath_status,
2071 .message = multipath_message,
2072 .prepare_ioctl = multipath_prepare_ioctl,
2073 .iterate_devices = multipath_iterate_devices,
2074 .busy = multipath_busy,
2075 };
2076
2077 static int __init dm_multipath_init(void)
2078 {
2079 int r;
2080
2081 kmultipathd = alloc_workqueue("kmpathd", WQ_MEM_RECLAIM, 0);
2082 if (!kmultipathd) {
2083 DMERR("failed to create workqueue kmpathd");
2084 r = -ENOMEM;
2085 goto bad_alloc_kmultipathd;
2086 }
2087
2088 /*
2089 * A separate workqueue is used to handle the device handlers
2090 * to avoid overloading existing workqueue. Overloading the
2091 * old workqueue would also create a bottleneck in the
2092 * path of the storage hardware device activation.
2093 */
2094 kmpath_handlerd = alloc_ordered_workqueue("kmpath_handlerd",
2095 WQ_MEM_RECLAIM);
2096 if (!kmpath_handlerd) {
2097 DMERR("failed to create workqueue kmpath_handlerd");
2098 r = -ENOMEM;
2099 goto bad_alloc_kmpath_handlerd;
2100 }
2101
2102 r = dm_register_target(&multipath_target);
2103 if (r < 0) {
2104 DMERR("request-based register failed %d", r);
2105 r = -EINVAL;
2106 goto bad_register_target;
2107 }
2108
2109 return 0;
2110
2111 bad_register_target:
2112 destroy_workqueue(kmpath_handlerd);
2113 bad_alloc_kmpath_handlerd:
2114 destroy_workqueue(kmultipathd);
2115 bad_alloc_kmultipathd:
2116 return r;
2117 }
2118
2119 static void __exit dm_multipath_exit(void)
2120 {
2121 destroy_workqueue(kmpath_handlerd);
2122 destroy_workqueue(kmultipathd);
2123
2124 dm_unregister_target(&multipath_target);
2125 }
2126
2127 module_init(dm_multipath_init);
2128 module_exit(dm_multipath_exit);
2129
2130 module_param_named(queue_if_no_path_timeout_secs,
2131 queue_if_no_path_timeout_secs, ulong, S_IRUGO | S_IWUSR);
2132 MODULE_PARM_DESC(queue_if_no_path_timeout_secs, "No available paths queue IO timeout in seconds");
2133
2134 MODULE_DESCRIPTION(DM_NAME " multipath target");
2135 MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
2136 MODULE_LICENSE("GPL");
Linux with added FPC-III support