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