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Restartable sequences: powerpc architecture support
[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 bool r;
511 unsigned long flags;
512
513 spin_lock_irqsave(&m->lock, flags);
514 r = (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) ||
515 __must_push_back(m));
516 spin_unlock_irqrestore(&m->lock, flags);
517
518 return r;
519 }
520
521 static bool must_push_back_bio(struct multipath *m)
522 {
523 bool r;
524 unsigned long flags;
525
526 spin_lock_irqsave(&m->lock, flags);
527 r = __must_push_back(m);
528 spin_unlock_irqrestore(&m->lock, flags);
529
530 return r;
531 }
532
533 /*
534 * Map cloned requests (request-based multipath)
535 */
536 static int __multipath_map(struct dm_target *ti, struct request *clone,
537 union map_info *map_context,
538 struct request *rq, struct request **__clone)
539 {
540 struct multipath *m = ti->private;
541 int r = DM_MAPIO_REQUEUE;
542 size_t nr_bytes = clone ? blk_rq_bytes(clone) : blk_rq_bytes(rq);
543 struct pgpath *pgpath;
544 struct block_device *bdev;
545 struct dm_mpath_io *mpio;
546
547 /* Do we need to select a new pgpath? */
548 pgpath = lockless_dereference(m->current_pgpath);
549 if (!pgpath || !test_bit(MPATHF_QUEUE_IO, &m->flags))
550 pgpath = choose_pgpath(m, nr_bytes);
551
552 if (!pgpath) {
553 if (!must_push_back_rq(m))
554 r = -EIO; /* Failed */
555 return r;
556 } else if (test_bit(MPATHF_QUEUE_IO, &m->flags) ||
557 test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags)) {
558 pg_init_all_paths(m);
559 return r;
560 }
561
562 mpio = set_mpio(m, map_context);
563 if (!mpio)
564 /* ENOMEM, requeue */
565 return r;
566
567 mpio->pgpath = pgpath;
568 mpio->nr_bytes = nr_bytes;
569
570 bdev = pgpath->path.dev->bdev;
571
572 if (clone) {
573 /*
574 * Old request-based interface: allocated clone is passed in.
575 * Used by: .request_fn stacked on .request_fn path(s).
576 */
577 clone->q = bdev_get_queue(bdev);
578 clone->rq_disk = bdev->bd_disk;
579 clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
580 } else {
581 /*
582 * blk-mq request-based interface; used by both:
583 * .request_fn stacked on blk-mq path(s) and
584 * blk-mq stacked on blk-mq path(s).
585 */
586 *__clone = blk_mq_alloc_request(bdev_get_queue(bdev),
587 rq_data_dir(rq), BLK_MQ_REQ_NOWAIT);
588 if (IS_ERR(*__clone)) {
589 /* ENOMEM, requeue */
590 clear_request_fn_mpio(m, map_context);
591 return r;
592 }
593 (*__clone)->bio = (*__clone)->biotail = NULL;
594 (*__clone)->rq_disk = bdev->bd_disk;
595 (*__clone)->cmd_flags |= REQ_FAILFAST_TRANSPORT;
596 }
597
598 if (pgpath->pg->ps.type->start_io)
599 pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
600 &pgpath->path,
601 nr_bytes);
602 return DM_MAPIO_REMAPPED;
603 }
604
605 static int multipath_map(struct dm_target *ti, struct request *clone,
606 union map_info *map_context)
607 {
608 return __multipath_map(ti, clone, map_context, NULL, NULL);
609 }
610
611 static int multipath_clone_and_map(struct dm_target *ti, struct request *rq,
612 union map_info *map_context,
613 struct request **clone)
614 {
615 return __multipath_map(ti, NULL, map_context, rq, clone);
616 }
617
618 static void multipath_release_clone(struct request *clone)
619 {
620 blk_mq_free_request(clone);
621 }
622
623 /*
624 * Map cloned bios (bio-based multipath)
625 */
626 static int __multipath_map_bio(struct multipath *m, struct bio *bio, struct dm_mpath_io *mpio)
627 {
628 size_t nr_bytes = bio->bi_iter.bi_size;
629 struct pgpath *pgpath;
630 unsigned long flags;
631 bool queue_io;
632
633 /* Do we need to select a new pgpath? */
634 pgpath = lockless_dereference(m->current_pgpath);
635 queue_io = test_bit(MPATHF_QUEUE_IO, &m->flags);
636 if (!pgpath || !queue_io)
637 pgpath = choose_pgpath(m, nr_bytes);
638
639 if ((pgpath && queue_io) ||
640 (!pgpath && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))) {
641 /* Queue for the daemon to resubmit */
642 spin_lock_irqsave(&m->lock, flags);
643 bio_list_add(&m->queued_bios, bio);
644 spin_unlock_irqrestore(&m->lock, flags);
645 /* PG_INIT_REQUIRED cannot be set without QUEUE_IO */
646 if (queue_io || test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
647 pg_init_all_paths(m);
648 else if (!queue_io)
649 queue_work(kmultipathd, &m->process_queued_bios);
650 return DM_MAPIO_SUBMITTED;
651 }
652
653 if (!pgpath) {
654 if (!must_push_back_bio(m))
655 return -EIO;
656 return DM_MAPIO_REQUEUE;
657 }
658
659 mpio->pgpath = pgpath;
660 mpio->nr_bytes = nr_bytes;
661
662 bio->bi_error = 0;
663 bio->bi_bdev = pgpath->path.dev->bdev;
664 bio->bi_opf |= REQ_FAILFAST_TRANSPORT;
665
666 if (pgpath->pg->ps.type->start_io)
667 pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
668 &pgpath->path,
669 nr_bytes);
670 return DM_MAPIO_REMAPPED;
671 }
672
673 static int multipath_map_bio(struct dm_target *ti, struct bio *bio)
674 {
675 struct multipath *m = ti->private;
676 struct dm_mpath_io *mpio = NULL;
677
678 multipath_init_per_bio_data(bio, &mpio, NULL);
679
680 return __multipath_map_bio(m, bio, mpio);
681 }
682
683 static void process_queued_bios_list(struct multipath *m)
684 {
685 if (m->queue_mode == DM_TYPE_BIO_BASED)
686 queue_work(kmultipathd, &m->process_queued_bios);
687 }
688
689 static void process_queued_bios(struct work_struct *work)
690 {
691 int r;
692 unsigned long flags;
693 struct bio *bio;
694 struct bio_list bios;
695 struct blk_plug plug;
696 struct multipath *m =
697 container_of(work, struct multipath, process_queued_bios);
698
699 bio_list_init(&bios);
700
701 spin_lock_irqsave(&m->lock, flags);
702
703 if (bio_list_empty(&m->queued_bios)) {
704 spin_unlock_irqrestore(&m->lock, flags);
705 return;
706 }
707
708 bio_list_merge(&bios, &m->queued_bios);
709 bio_list_init(&m->queued_bios);
710
711 spin_unlock_irqrestore(&m->lock, flags);
712
713 blk_start_plug(&plug);
714 while ((bio = bio_list_pop(&bios))) {
715 r = __multipath_map_bio(m, bio, get_mpio_from_bio(bio));
716 if (r < 0 || r == DM_MAPIO_REQUEUE) {
717 bio->bi_error = r;
718 bio_endio(bio);
719 } else if (r == DM_MAPIO_REMAPPED)
720 generic_make_request(bio);
721 }
722 blk_finish_plug(&plug);
723 }
724
725 /*
726 * If we run out of usable paths, should we queue I/O or error it?
727 */
728 static int queue_if_no_path(struct multipath *m, bool queue_if_no_path,
729 bool save_old_value)
730 {
731 unsigned long flags;
732
733 spin_lock_irqsave(&m->lock, flags);
734
735 if (save_old_value) {
736 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
737 set_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
738 else
739 clear_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
740 } else {
741 if (queue_if_no_path)
742 set_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
743 else
744 clear_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
745 }
746 if (queue_if_no_path)
747 set_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
748 else
749 clear_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
750
751 spin_unlock_irqrestore(&m->lock, flags);
752
753 if (!queue_if_no_path) {
754 dm_table_run_md_queue_async(m->ti->table);
755 process_queued_bios_list(m);
756 }
757
758 return 0;
759 }
760
761 /*
762 * An event is triggered whenever a path is taken out of use.
763 * Includes path failure and PG bypass.
764 */
765 static void trigger_event(struct work_struct *work)
766 {
767 struct multipath *m =
768 container_of(work, struct multipath, trigger_event);
769
770 dm_table_event(m->ti->table);
771 }
772
773 /*-----------------------------------------------------------------
774 * Constructor/argument parsing:
775 * <#multipath feature args> [<arg>]*
776 * <#hw_handler args> [hw_handler [<arg>]*]
777 * <#priority groups>
778 * <initial priority group>
779 * [<selector> <#selector args> [<arg>]*
780 * <#paths> <#per-path selector args>
781 * [<path> [<arg>]* ]+ ]+
782 *---------------------------------------------------------------*/
783 static int parse_path_selector(struct dm_arg_set *as, struct priority_group *pg,
784 struct dm_target *ti)
785 {
786 int r;
787 struct path_selector_type *pst;
788 unsigned ps_argc;
789
790 static struct dm_arg _args[] = {
791 {0, 1024, "invalid number of path selector args"},
792 };
793
794 pst = dm_get_path_selector(dm_shift_arg(as));
795 if (!pst) {
796 ti->error = "unknown path selector type";
797 return -EINVAL;
798 }
799
800 r = dm_read_arg_group(_args, as, &ps_argc, &ti->error);
801 if (r) {
802 dm_put_path_selector(pst);
803 return -EINVAL;
804 }
805
806 r = pst->create(&pg->ps, ps_argc, as->argv);
807 if (r) {
808 dm_put_path_selector(pst);
809 ti->error = "path selector constructor failed";
810 return r;
811 }
812
813 pg->ps.type = pst;
814 dm_consume_args(as, ps_argc);
815
816 return 0;
817 }
818
819 static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps,
820 struct dm_target *ti)
821 {
822 int r;
823 struct pgpath *p;
824 struct multipath *m = ti->private;
825 struct request_queue *q = NULL;
826 const char *attached_handler_name;
827
828 /* we need at least a path arg */
829 if (as->argc < 1) {
830 ti->error = "no device given";
831 return ERR_PTR(-EINVAL);
832 }
833
834 p = alloc_pgpath();
835 if (!p)
836 return ERR_PTR(-ENOMEM);
837
838 r = dm_get_device(ti, dm_shift_arg(as), dm_table_get_mode(ti->table),
839 &p->path.dev);
840 if (r) {
841 ti->error = "error getting device";
842 goto bad;
843 }
844
845 if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags) || m->hw_handler_name)
846 q = bdev_get_queue(p->path.dev->bdev);
847
848 if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags)) {
849 retain:
850 attached_handler_name = scsi_dh_attached_handler_name(q, GFP_KERNEL);
851 if (attached_handler_name) {
852 /*
853 * Reset hw_handler_name to match the attached handler
854 * and clear any hw_handler_params associated with the
855 * ignored handler.
856 *
857 * NB. This modifies the table line to show the actual
858 * handler instead of the original table passed in.
859 */
860 kfree(m->hw_handler_name);
861 m->hw_handler_name = attached_handler_name;
862
863 kfree(m->hw_handler_params);
864 m->hw_handler_params = NULL;
865 }
866 }
867
868 if (m->hw_handler_name) {
869 r = scsi_dh_attach(q, m->hw_handler_name);
870 if (r == -EBUSY) {
871 char b[BDEVNAME_SIZE];
872
873 printk(KERN_INFO "dm-mpath: retaining handler on device %s\n",
874 bdevname(p->path.dev->bdev, b));
875 goto retain;
876 }
877 if (r < 0) {
878 ti->error = "error attaching hardware handler";
879 dm_put_device(ti, p->path.dev);
880 goto bad;
881 }
882
883 if (m->hw_handler_params) {
884 r = scsi_dh_set_params(q, m->hw_handler_params);
885 if (r < 0) {
886 ti->error = "unable to set hardware "
887 "handler parameters";
888 dm_put_device(ti, p->path.dev);
889 goto bad;
890 }
891 }
892 }
893
894 r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
895 if (r) {
896 dm_put_device(ti, p->path.dev);
897 goto bad;
898 }
899
900 return p;
901
902 bad:
903 free_pgpath(p);
904 return ERR_PTR(r);
905 }
906
907 static struct priority_group *parse_priority_group(struct dm_arg_set *as,
908 struct multipath *m)
909 {
910 static struct dm_arg _args[] = {
911 {1, 1024, "invalid number of paths"},
912 {0, 1024, "invalid number of selector args"}
913 };
914
915 int r;
916 unsigned i, nr_selector_args, nr_args;
917 struct priority_group *pg;
918 struct dm_target *ti = m->ti;
919
920 if (as->argc < 2) {
921 as->argc = 0;
922 ti->error = "not enough priority group arguments";
923 return ERR_PTR(-EINVAL);
924 }
925
926 pg = alloc_priority_group();
927 if (!pg) {
928 ti->error = "couldn't allocate priority group";
929 return ERR_PTR(-ENOMEM);
930 }
931 pg->m = m;
932
933 r = parse_path_selector(as, pg, ti);
934 if (r)
935 goto bad;
936
937 /*
938 * read the paths
939 */
940 r = dm_read_arg(_args, as, &pg->nr_pgpaths, &ti->error);
941 if (r)
942 goto bad;
943
944 r = dm_read_arg(_args + 1, as, &nr_selector_args, &ti->error);
945 if (r)
946 goto bad;
947
948 nr_args = 1 + nr_selector_args;
949 for (i = 0; i < pg->nr_pgpaths; i++) {
950 struct pgpath *pgpath;
951 struct dm_arg_set path_args;
952
953 if (as->argc < nr_args) {
954 ti->error = "not enough path parameters";
955 r = -EINVAL;
956 goto bad;
957 }
958
959 path_args.argc = nr_args;
960 path_args.argv = as->argv;
961
962 pgpath = parse_path(&path_args, &pg->ps, ti);
963 if (IS_ERR(pgpath)) {
964 r = PTR_ERR(pgpath);
965 goto bad;
966 }
967
968 pgpath->pg = pg;
969 list_add_tail(&pgpath->list, &pg->pgpaths);
970 dm_consume_args(as, nr_args);
971 }
972
973 return pg;
974
975 bad:
976 free_priority_group(pg, ti);
977 return ERR_PTR(r);
978 }
979
980 static int parse_hw_handler(struct dm_arg_set *as, struct multipath *m)
981 {
982 unsigned hw_argc;
983 int ret;
984 struct dm_target *ti = m->ti;
985
986 static struct dm_arg _args[] = {
987 {0, 1024, "invalid number of hardware handler args"},
988 };
989
990 if (dm_read_arg_group(_args, as, &hw_argc, &ti->error))
991 return -EINVAL;
992
993 if (!hw_argc)
994 return 0;
995
996 if (m->queue_mode == DM_TYPE_BIO_BASED) {
997 dm_consume_args(as, hw_argc);
998 DMERR("bio-based multipath doesn't allow hardware handler args");
999 return 0;
1000 }
1001
1002 m->hw_handler_name = kstrdup(dm_shift_arg(as), GFP_KERNEL);
1003
1004 if (hw_argc > 1) {
1005 char *p;
1006 int i, j, len = 4;
1007
1008 for (i = 0; i <= hw_argc - 2; i++)
1009 len += strlen(as->argv[i]) + 1;
1010 p = m->hw_handler_params = kzalloc(len, GFP_KERNEL);
1011 if (!p) {
1012 ti->error = "memory allocation failed";
1013 ret = -ENOMEM;
1014 goto fail;
1015 }
1016 j = sprintf(p, "%d", hw_argc - 1);
1017 for (i = 0, p+=j+1; i <= hw_argc - 2; i++, p+=j+1)
1018 j = sprintf(p, "%s", as->argv[i]);
1019 }
1020 dm_consume_args(as, hw_argc - 1);
1021
1022 return 0;
1023 fail:
1024 kfree(m->hw_handler_name);
1025 m->hw_handler_name = NULL;
1026 return ret;
1027 }
1028
1029 static int parse_features(struct dm_arg_set *as, struct multipath *m)
1030 {
1031 int r;
1032 unsigned argc;
1033 struct dm_target *ti = m->ti;
1034 const char *arg_name;
1035
1036 static struct dm_arg _args[] = {
1037 {0, 8, "invalid number of feature args"},
1038 {1, 50, "pg_init_retries must be between 1 and 50"},
1039 {0, 60000, "pg_init_delay_msecs must be between 0 and 60000"},
1040 };
1041
1042 r = dm_read_arg_group(_args, as, &argc, &ti->error);
1043 if (r)
1044 return -EINVAL;
1045
1046 if (!argc)
1047 return 0;
1048
1049 do {
1050 arg_name = dm_shift_arg(as);
1051 argc--;
1052
1053 if (!strcasecmp(arg_name, "queue_if_no_path")) {
1054 r = queue_if_no_path(m, true, false);
1055 continue;
1056 }
1057
1058 if (!strcasecmp(arg_name, "retain_attached_hw_handler")) {
1059 set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags);
1060 continue;
1061 }
1062
1063 if (!strcasecmp(arg_name, "pg_init_retries") &&
1064 (argc >= 1)) {
1065 r = dm_read_arg(_args + 1, as, &m->pg_init_retries, &ti->error);
1066 argc--;
1067 continue;
1068 }
1069
1070 if (!strcasecmp(arg_name, "pg_init_delay_msecs") &&
1071 (argc >= 1)) {
1072 r = dm_read_arg(_args + 2, as, &m->pg_init_delay_msecs, &ti->error);
1073 argc--;
1074 continue;
1075 }
1076
1077 if (!strcasecmp(arg_name, "queue_mode") &&
1078 (argc >= 1)) {
1079 const char *queue_mode_name = dm_shift_arg(as);
1080
1081 if (!strcasecmp(queue_mode_name, "bio"))
1082 m->queue_mode = DM_TYPE_BIO_BASED;
1083 else if (!strcasecmp(queue_mode_name, "rq"))
1084 m->queue_mode = DM_TYPE_REQUEST_BASED;
1085 else if (!strcasecmp(queue_mode_name, "mq"))
1086 m->queue_mode = DM_TYPE_MQ_REQUEST_BASED;
1087 else {
1088 ti->error = "Unknown 'queue_mode' requested";
1089 r = -EINVAL;
1090 }
1091 argc--;
1092 continue;
1093 }
1094
1095 ti->error = "Unrecognised multipath feature request";
1096 r = -EINVAL;
1097 } while (argc && !r);
1098
1099 return r;
1100 }
1101
1102 static int multipath_ctr(struct dm_target *ti, unsigned argc, char **argv)
1103 {
1104 /* target arguments */
1105 static struct dm_arg _args[] = {
1106 {0, 1024, "invalid number of priority groups"},
1107 {0, 1024, "invalid initial priority group number"},
1108 };
1109
1110 int r;
1111 struct multipath *m;
1112 struct dm_arg_set as;
1113 unsigned pg_count = 0;
1114 unsigned next_pg_num;
1115
1116 as.argc = argc;
1117 as.argv = argv;
1118
1119 m = alloc_multipath(ti);
1120 if (!m) {
1121 ti->error = "can't allocate multipath";
1122 return -EINVAL;
1123 }
1124
1125 r = parse_features(&as, m);
1126 if (r)
1127 goto bad;
1128
1129 r = alloc_multipath_stage2(ti, m);
1130 if (r)
1131 goto bad;
1132
1133 r = parse_hw_handler(&as, m);
1134 if (r)
1135 goto bad;
1136
1137 r = dm_read_arg(_args, &as, &m->nr_priority_groups, &ti->error);
1138 if (r)
1139 goto bad;
1140
1141 r = dm_read_arg(_args + 1, &as, &next_pg_num, &ti->error);
1142 if (r)
1143 goto bad;
1144
1145 if ((!m->nr_priority_groups && next_pg_num) ||
1146 (m->nr_priority_groups && !next_pg_num)) {
1147 ti->error = "invalid initial priority group";
1148 r = -EINVAL;
1149 goto bad;
1150 }
1151
1152 /* parse the priority groups */
1153 while (as.argc) {
1154 struct priority_group *pg;
1155 unsigned nr_valid_paths = atomic_read(&m->nr_valid_paths);
1156
1157 pg = parse_priority_group(&as, m);
1158 if (IS_ERR(pg)) {
1159 r = PTR_ERR(pg);
1160 goto bad;
1161 }
1162
1163 nr_valid_paths += pg->nr_pgpaths;
1164 atomic_set(&m->nr_valid_paths, nr_valid_paths);
1165
1166 list_add_tail(&pg->list, &m->priority_groups);
1167 pg_count++;
1168 pg->pg_num = pg_count;
1169 if (!--next_pg_num)
1170 m->next_pg = pg;
1171 }
1172
1173 if (pg_count != m->nr_priority_groups) {
1174 ti->error = "priority group count mismatch";
1175 r = -EINVAL;
1176 goto bad;
1177 }
1178
1179 ti->num_flush_bios = 1;
1180 ti->num_discard_bios = 1;
1181 ti->num_write_same_bios = 1;
1182 if (m->queue_mode == DM_TYPE_BIO_BASED)
1183 ti->per_io_data_size = multipath_per_bio_data_size();
1184 else if (m->queue_mode == DM_TYPE_MQ_REQUEST_BASED)
1185 ti->per_io_data_size = sizeof(struct dm_mpath_io);
1186
1187 return 0;
1188
1189 bad:
1190 free_multipath(m);
1191 return r;
1192 }
1193
1194 static void multipath_wait_for_pg_init_completion(struct multipath *m)
1195 {
1196 DECLARE_WAITQUEUE(wait, current);
1197
1198 add_wait_queue(&m->pg_init_wait, &wait);
1199
1200 while (1) {
1201 set_current_state(TASK_UNINTERRUPTIBLE);
1202
1203 if (!atomic_read(&m->pg_init_in_progress))
1204 break;
1205
1206 io_schedule();
1207 }
1208 set_current_state(TASK_RUNNING);
1209
1210 remove_wait_queue(&m->pg_init_wait, &wait);
1211 }
1212
1213 static void flush_multipath_work(struct multipath *m)
1214 {
1215 set_bit(MPATHF_PG_INIT_DISABLED, &m->flags);
1216 smp_mb__after_atomic();
1217
1218 flush_workqueue(kmpath_handlerd);
1219 multipath_wait_for_pg_init_completion(m);
1220 flush_workqueue(kmultipathd);
1221 flush_work(&m->trigger_event);
1222
1223 clear_bit(MPATHF_PG_INIT_DISABLED, &m->flags);
1224 smp_mb__after_atomic();
1225 }
1226
1227 static void multipath_dtr(struct dm_target *ti)
1228 {
1229 struct multipath *m = ti->private;
1230
1231 flush_multipath_work(m);
1232 free_multipath(m);
1233 }
1234
1235 /*
1236 * Take a path out of use.
1237 */
1238 static int fail_path(struct pgpath *pgpath)
1239 {
1240 unsigned long flags;
1241 struct multipath *m = pgpath->pg->m;
1242
1243 spin_lock_irqsave(&m->lock, flags);
1244
1245 if (!pgpath->is_active)
1246 goto out;
1247
1248 DMWARN("Failing path %s.", pgpath->path.dev->name);
1249
1250 pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
1251 pgpath->is_active = false;
1252 pgpath->fail_count++;
1253
1254 atomic_dec(&m->nr_valid_paths);
1255
1256 if (pgpath == m->current_pgpath)
1257 m->current_pgpath = NULL;
1258
1259 dm_path_uevent(DM_UEVENT_PATH_FAILED, m->ti,
1260 pgpath->path.dev->name, atomic_read(&m->nr_valid_paths));
1261
1262 schedule_work(&m->trigger_event);
1263
1264 out:
1265 spin_unlock_irqrestore(&m->lock, flags);
1266
1267 return 0;
1268 }
1269
1270 /*
1271 * Reinstate a previously-failed path
1272 */
1273 static int reinstate_path(struct pgpath *pgpath)
1274 {
1275 int r = 0, run_queue = 0;
1276 unsigned long flags;
1277 struct multipath *m = pgpath->pg->m;
1278 unsigned nr_valid_paths;
1279
1280 spin_lock_irqsave(&m->lock, flags);
1281
1282 if (pgpath->is_active)
1283 goto out;
1284
1285 DMWARN("Reinstating path %s.", pgpath->path.dev->name);
1286
1287 r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
1288 if (r)
1289 goto out;
1290
1291 pgpath->is_active = true;
1292
1293 nr_valid_paths = atomic_inc_return(&m->nr_valid_paths);
1294 if (nr_valid_paths == 1) {
1295 m->current_pgpath = NULL;
1296 run_queue = 1;
1297 } else if (m->hw_handler_name && (m->current_pg == pgpath->pg)) {
1298 if (queue_work(kmpath_handlerd, &pgpath->activate_path.work))
1299 atomic_inc(&m->pg_init_in_progress);
1300 }
1301
1302 dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti,
1303 pgpath->path.dev->name, nr_valid_paths);
1304
1305 schedule_work(&m->trigger_event);
1306
1307 out:
1308 spin_unlock_irqrestore(&m->lock, flags);
1309 if (run_queue) {
1310 dm_table_run_md_queue_async(m->ti->table);
1311 process_queued_bios_list(m);
1312 }
1313
1314 return r;
1315 }
1316
1317 /*
1318 * Fail or reinstate all paths that match the provided struct dm_dev.
1319 */
1320 static int action_dev(struct multipath *m, struct dm_dev *dev,
1321 action_fn action)
1322 {
1323 int r = -EINVAL;
1324 struct pgpath *pgpath;
1325 struct priority_group *pg;
1326
1327 list_for_each_entry(pg, &m->priority_groups, list) {
1328 list_for_each_entry(pgpath, &pg->pgpaths, list) {
1329 if (pgpath->path.dev == dev)
1330 r = action(pgpath);
1331 }
1332 }
1333
1334 return r;
1335 }
1336
1337 /*
1338 * Temporarily try to avoid having to use the specified PG
1339 */
1340 static void bypass_pg(struct multipath *m, struct priority_group *pg,
1341 bool bypassed)
1342 {
1343 unsigned long flags;
1344
1345 spin_lock_irqsave(&m->lock, flags);
1346
1347 pg->bypassed = bypassed;
1348 m->current_pgpath = NULL;
1349 m->current_pg = NULL;
1350
1351 spin_unlock_irqrestore(&m->lock, flags);
1352
1353 schedule_work(&m->trigger_event);
1354 }
1355
1356 /*
1357 * Switch to using the specified PG from the next I/O that gets mapped
1358 */
1359 static int switch_pg_num(struct multipath *m, const char *pgstr)
1360 {
1361 struct priority_group *pg;
1362 unsigned pgnum;
1363 unsigned long flags;
1364 char dummy;
1365
1366 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1367 (pgnum > m->nr_priority_groups)) {
1368 DMWARN("invalid PG number supplied to switch_pg_num");
1369 return -EINVAL;
1370 }
1371
1372 spin_lock_irqsave(&m->lock, flags);
1373 list_for_each_entry(pg, &m->priority_groups, list) {
1374 pg->bypassed = false;
1375 if (--pgnum)
1376 continue;
1377
1378 m->current_pgpath = NULL;
1379 m->current_pg = NULL;
1380 m->next_pg = pg;
1381 }
1382 spin_unlock_irqrestore(&m->lock, flags);
1383
1384 schedule_work(&m->trigger_event);
1385 return 0;
1386 }
1387
1388 /*
1389 * Set/clear bypassed status of a PG.
1390 * PGs are numbered upwards from 1 in the order they were declared.
1391 */
1392 static int bypass_pg_num(struct multipath *m, const char *pgstr, bool bypassed)
1393 {
1394 struct priority_group *pg;
1395 unsigned pgnum;
1396 char dummy;
1397
1398 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1399 (pgnum > m->nr_priority_groups)) {
1400 DMWARN("invalid PG number supplied to bypass_pg");
1401 return -EINVAL;
1402 }
1403
1404 list_for_each_entry(pg, &m->priority_groups, list) {
1405 if (!--pgnum)
1406 break;
1407 }
1408
1409 bypass_pg(m, pg, bypassed);
1410 return 0;
1411 }
1412
1413 /*
1414 * Should we retry pg_init immediately?
1415 */
1416 static bool pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath)
1417 {
1418 unsigned long flags;
1419 bool limit_reached = false;
1420
1421 spin_lock_irqsave(&m->lock, flags);
1422
1423 if (atomic_read(&m->pg_init_count) <= m->pg_init_retries &&
1424 !test_bit(MPATHF_PG_INIT_DISABLED, &m->flags))
1425 set_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
1426 else
1427 limit_reached = true;
1428
1429 spin_unlock_irqrestore(&m->lock, flags);
1430
1431 return limit_reached;
1432 }
1433
1434 static void pg_init_done(void *data, int errors)
1435 {
1436 struct pgpath *pgpath = data;
1437 struct priority_group *pg = pgpath->pg;
1438 struct multipath *m = pg->m;
1439 unsigned long flags;
1440 bool delay_retry = false;
1441
1442 /* device or driver problems */
1443 switch (errors) {
1444 case SCSI_DH_OK:
1445 break;
1446 case SCSI_DH_NOSYS:
1447 if (!m->hw_handler_name) {
1448 errors = 0;
1449 break;
1450 }
1451 DMERR("Could not failover the device: Handler scsi_dh_%s "
1452 "Error %d.", m->hw_handler_name, errors);
1453 /*
1454 * Fail path for now, so we do not ping pong
1455 */
1456 fail_path(pgpath);
1457 break;
1458 case SCSI_DH_DEV_TEMP_BUSY:
1459 /*
1460 * Probably doing something like FW upgrade on the
1461 * controller so try the other pg.
1462 */
1463 bypass_pg(m, pg, true);
1464 break;
1465 case SCSI_DH_RETRY:
1466 /* Wait before retrying. */
1467 delay_retry = 1;
1468 case SCSI_DH_IMM_RETRY:
1469 case SCSI_DH_RES_TEMP_UNAVAIL:
1470 if (pg_init_limit_reached(m, pgpath))
1471 fail_path(pgpath);
1472 errors = 0;
1473 break;
1474 case SCSI_DH_DEV_OFFLINED:
1475 default:
1476 /*
1477 * We probably do not want to fail the path for a device
1478 * error, but this is what the old dm did. In future
1479 * patches we can do more advanced handling.
1480 */
1481 fail_path(pgpath);
1482 }
1483
1484 spin_lock_irqsave(&m->lock, flags);
1485 if (errors) {
1486 if (pgpath == m->current_pgpath) {
1487 DMERR("Could not failover device. Error %d.", errors);
1488 m->current_pgpath = NULL;
1489 m->current_pg = NULL;
1490 }
1491 } else if (!test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
1492 pg->bypassed = false;
1493
1494 if (atomic_dec_return(&m->pg_init_in_progress) > 0)
1495 /* Activations of other paths are still on going */
1496 goto out;
1497
1498 if (test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags)) {
1499 if (delay_retry)
1500 set_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
1501 else
1502 clear_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
1503
1504 if (__pg_init_all_paths(m))
1505 goto out;
1506 }
1507 clear_bit(MPATHF_QUEUE_IO, &m->flags);
1508
1509 process_queued_bios_list(m);
1510
1511 /*
1512 * Wake up any thread waiting to suspend.
1513 */
1514 wake_up(&m->pg_init_wait);
1515
1516 out:
1517 spin_unlock_irqrestore(&m->lock, flags);
1518 }
1519
1520 static void activate_path(struct work_struct *work)
1521 {
1522 struct pgpath *pgpath =
1523 container_of(work, struct pgpath, activate_path.work);
1524
1525 if (pgpath->is_active)
1526 scsi_dh_activate(bdev_get_queue(pgpath->path.dev->bdev),
1527 pg_init_done, pgpath);
1528 else
1529 pg_init_done(pgpath, SCSI_DH_DEV_OFFLINED);
1530 }
1531
1532 static int noretry_error(int error)
1533 {
1534 switch (error) {
1535 case -EOPNOTSUPP:
1536 case -EREMOTEIO:
1537 case -EILSEQ:
1538 case -ENODATA:
1539 case -ENOSPC:
1540 return 1;
1541 }
1542
1543 /* Anything else could be a path failure, so should be retried */
1544 return 0;
1545 }
1546
1547 /*
1548 * end_io handling
1549 */
1550 static int do_end_io(struct multipath *m, struct request *clone,
1551 int error, struct dm_mpath_io *mpio)
1552 {
1553 /*
1554 * We don't queue any clone request inside the multipath target
1555 * during end I/O handling, since those clone requests don't have
1556 * bio clones. If we queue them inside the multipath target,
1557 * we need to make bio clones, that requires memory allocation.
1558 * (See drivers/md/dm-rq.c:end_clone_bio() about why the clone requests
1559 * don't have bio clones.)
1560 * Instead of queueing the clone request here, we queue the original
1561 * request into dm core, which will remake a clone request and
1562 * clone bios for it and resubmit it later.
1563 */
1564 int r = DM_ENDIO_REQUEUE;
1565
1566 if (!error && !clone->errors)
1567 return 0; /* I/O complete */
1568
1569 if (noretry_error(error))
1570 return error;
1571
1572 if (mpio->pgpath)
1573 fail_path(mpio->pgpath);
1574
1575 if (!atomic_read(&m->nr_valid_paths)) {
1576 if (!test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
1577 if (!must_push_back_rq(m))
1578 r = -EIO;
1579 } else {
1580 if (error == -EBADE)
1581 r = error;
1582 }
1583 }
1584
1585 return r;
1586 }
1587
1588 static int multipath_end_io(struct dm_target *ti, struct request *clone,
1589 int error, union map_info *map_context)
1590 {
1591 struct multipath *m = ti->private;
1592 struct dm_mpath_io *mpio = get_mpio(map_context);
1593 struct pgpath *pgpath;
1594 struct path_selector *ps;
1595 int r;
1596
1597 BUG_ON(!mpio);
1598
1599 r = do_end_io(m, clone, error, mpio);
1600 pgpath = mpio->pgpath;
1601 if (pgpath) {
1602 ps = &pgpath->pg->ps;
1603 if (ps->type->end_io)
1604 ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
1605 }
1606 clear_request_fn_mpio(m, map_context);
1607
1608 return r;
1609 }
1610
1611 static int do_end_io_bio(struct multipath *m, struct bio *clone,
1612 int error, struct dm_mpath_io *mpio)
1613 {
1614 unsigned long flags;
1615
1616 if (!error)
1617 return 0; /* I/O complete */
1618
1619 if (noretry_error(error))
1620 return error;
1621
1622 if (mpio->pgpath)
1623 fail_path(mpio->pgpath);
1624
1625 if (!atomic_read(&m->nr_valid_paths)) {
1626 if (!test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
1627 if (!must_push_back_bio(m))
1628 return -EIO;
1629 return DM_ENDIO_REQUEUE;
1630 } else {
1631 if (error == -EBADE)
1632 return error;
1633 }
1634 }
1635
1636 /* Queue for the daemon to resubmit */
1637 dm_bio_restore(get_bio_details_from_bio(clone), clone);
1638
1639 spin_lock_irqsave(&m->lock, flags);
1640 bio_list_add(&m->queued_bios, clone);
1641 spin_unlock_irqrestore(&m->lock, flags);
1642 if (!test_bit(MPATHF_QUEUE_IO, &m->flags))
1643 queue_work(kmultipathd, &m->process_queued_bios);
1644
1645 return DM_ENDIO_INCOMPLETE;
1646 }
1647
1648 static int multipath_end_io_bio(struct dm_target *ti, struct bio *clone, int error)
1649 {
1650 struct multipath *m = ti->private;
1651 struct dm_mpath_io *mpio = get_mpio_from_bio(clone);
1652 struct pgpath *pgpath;
1653 struct path_selector *ps;
1654 int r;
1655
1656 BUG_ON(!mpio);
1657
1658 r = do_end_io_bio(m, clone, error, mpio);
1659 pgpath = mpio->pgpath;
1660 if (pgpath) {
1661 ps = &pgpath->pg->ps;
1662 if (ps->type->end_io)
1663 ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
1664 }
1665
1666 return r;
1667 }
1668
1669 /*
1670 * Suspend can't complete until all the I/O is processed so if
1671 * the last path fails we must error any remaining I/O.
1672 * Note that if the freeze_bdev fails while suspending, the
1673 * queue_if_no_path state is lost - userspace should reset it.
1674 */
1675 static void multipath_presuspend(struct dm_target *ti)
1676 {
1677 struct multipath *m = ti->private;
1678
1679 queue_if_no_path(m, false, true);
1680 }
1681
1682 static void multipath_postsuspend(struct dm_target *ti)
1683 {
1684 struct multipath *m = ti->private;
1685
1686 mutex_lock(&m->work_mutex);
1687 flush_multipath_work(m);
1688 mutex_unlock(&m->work_mutex);
1689 }
1690
1691 /*
1692 * Restore the queue_if_no_path setting.
1693 */
1694 static void multipath_resume(struct dm_target *ti)
1695 {
1696 struct multipath *m = ti->private;
1697 unsigned long flags;
1698
1699 spin_lock_irqsave(&m->lock, flags);
1700 if (test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags))
1701 set_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
1702 else
1703 clear_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
1704 spin_unlock_irqrestore(&m->lock, flags);
1705 }
1706
1707 /*
1708 * Info output has the following format:
1709 * num_multipath_feature_args [multipath_feature_args]*
1710 * num_handler_status_args [handler_status_args]*
1711 * num_groups init_group_number
1712 * [A|D|E num_ps_status_args [ps_status_args]*
1713 * num_paths num_selector_args
1714 * [path_dev A|F fail_count [selector_args]* ]+ ]+
1715 *
1716 * Table output has the following format (identical to the constructor string):
1717 * num_feature_args [features_args]*
1718 * num_handler_args hw_handler [hw_handler_args]*
1719 * num_groups init_group_number
1720 * [priority selector-name num_ps_args [ps_args]*
1721 * num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
1722 */
1723 static void multipath_status(struct dm_target *ti, status_type_t type,
1724 unsigned status_flags, char *result, unsigned maxlen)
1725 {
1726 int sz = 0;
1727 unsigned long flags;
1728 struct multipath *m = ti->private;
1729 struct priority_group *pg;
1730 struct pgpath *p;
1731 unsigned pg_num;
1732 char state;
1733
1734 spin_lock_irqsave(&m->lock, flags);
1735
1736 /* Features */
1737 if (type == STATUSTYPE_INFO)
1738 DMEMIT("2 %u %u ", test_bit(MPATHF_QUEUE_IO, &m->flags),
1739 atomic_read(&m->pg_init_count));
1740 else {
1741 DMEMIT("%u ", test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) +
1742 (m->pg_init_retries > 0) * 2 +
1743 (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT) * 2 +
1744 test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags) +
1745 (m->queue_mode != DM_TYPE_REQUEST_BASED) * 2);
1746
1747 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
1748 DMEMIT("queue_if_no_path ");
1749 if (m->pg_init_retries)
1750 DMEMIT("pg_init_retries %u ", m->pg_init_retries);
1751 if (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT)
1752 DMEMIT("pg_init_delay_msecs %u ", m->pg_init_delay_msecs);
1753 if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags))
1754 DMEMIT("retain_attached_hw_handler ");
1755 if (m->queue_mode != DM_TYPE_REQUEST_BASED) {
1756 switch(m->queue_mode) {
1757 case DM_TYPE_BIO_BASED:
1758 DMEMIT("queue_mode bio ");
1759 break;
1760 case DM_TYPE_MQ_REQUEST_BASED:
1761 DMEMIT("queue_mode mq ");
1762 break;
1763 }
1764 }
1765 }
1766
1767 if (!m->hw_handler_name || type == STATUSTYPE_INFO)
1768 DMEMIT("0 ");
1769 else
1770 DMEMIT("1 %s ", m->hw_handler_name);
1771
1772 DMEMIT("%u ", m->nr_priority_groups);
1773
1774 if (m->next_pg)
1775 pg_num = m->next_pg->pg_num;
1776 else if (m->current_pg)
1777 pg_num = m->current_pg->pg_num;
1778 else
1779 pg_num = (m->nr_priority_groups ? 1 : 0);
1780
1781 DMEMIT("%u ", pg_num);
1782
1783 switch (type) {
1784 case STATUSTYPE_INFO:
1785 list_for_each_entry(pg, &m->priority_groups, list) {
1786 if (pg->bypassed)
1787 state = 'D'; /* Disabled */
1788 else if (pg == m->current_pg)
1789 state = 'A'; /* Currently Active */
1790 else
1791 state = 'E'; /* Enabled */
1792
1793 DMEMIT("%c ", state);
1794
1795 if (pg->ps.type->status)
1796 sz += pg->ps.type->status(&pg->ps, NULL, type,
1797 result + sz,
1798 maxlen - sz);
1799 else
1800 DMEMIT("0 ");
1801
1802 DMEMIT("%u %u ", pg->nr_pgpaths,
1803 pg->ps.type->info_args);
1804
1805 list_for_each_entry(p, &pg->pgpaths, list) {
1806 DMEMIT("%s %s %u ", p->path.dev->name,
1807 p->is_active ? "A" : "F",
1808 p->fail_count);
1809 if (pg->ps.type->status)
1810 sz += pg->ps.type->status(&pg->ps,
1811 &p->path, type, result + sz,
1812 maxlen - sz);
1813 }
1814 }
1815 break;
1816
1817 case STATUSTYPE_TABLE:
1818 list_for_each_entry(pg, &m->priority_groups, list) {
1819 DMEMIT("%s ", pg->ps.type->name);
1820
1821 if (pg->ps.type->status)
1822 sz += pg->ps.type->status(&pg->ps, NULL, type,
1823 result + sz,
1824 maxlen - sz);
1825 else
1826 DMEMIT("0 ");
1827
1828 DMEMIT("%u %u ", pg->nr_pgpaths,
1829 pg->ps.type->table_args);
1830
1831 list_for_each_entry(p, &pg->pgpaths, list) {
1832 DMEMIT("%s ", p->path.dev->name);
1833 if (pg->ps.type->status)
1834 sz += pg->ps.type->status(&pg->ps,
1835 &p->path, type, result + sz,
1836 maxlen - sz);
1837 }
1838 }
1839 break;
1840 }
1841
1842 spin_unlock_irqrestore(&m->lock, flags);
1843 }
1844
1845 static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
1846 {
1847 int r = -EINVAL;
1848 struct dm_dev *dev;
1849 struct multipath *m = ti->private;
1850 action_fn action;
1851
1852 mutex_lock(&m->work_mutex);
1853
1854 if (dm_suspended(ti)) {
1855 r = -EBUSY;
1856 goto out;
1857 }
1858
1859 if (argc == 1) {
1860 if (!strcasecmp(argv[0], "queue_if_no_path")) {
1861 r = queue_if_no_path(m, true, false);
1862 goto out;
1863 } else if (!strcasecmp(argv[0], "fail_if_no_path")) {
1864 r = queue_if_no_path(m, false, false);
1865 goto out;
1866 }
1867 }
1868
1869 if (argc != 2) {
1870 DMWARN("Invalid multipath message arguments. Expected 2 arguments, got %d.", argc);
1871 goto out;
1872 }
1873
1874 if (!strcasecmp(argv[0], "disable_group")) {
1875 r = bypass_pg_num(m, argv[1], true);
1876 goto out;
1877 } else if (!strcasecmp(argv[0], "enable_group")) {
1878 r = bypass_pg_num(m, argv[1], false);
1879 goto out;
1880 } else if (!strcasecmp(argv[0], "switch_group")) {
1881 r = switch_pg_num(m, argv[1]);
1882 goto out;
1883 } else if (!strcasecmp(argv[0], "reinstate_path"))
1884 action = reinstate_path;
1885 else if (!strcasecmp(argv[0], "fail_path"))
1886 action = fail_path;
1887 else {
1888 DMWARN("Unrecognised multipath message received: %s", argv[0]);
1889 goto out;
1890 }
1891
1892 r = dm_get_device(ti, argv[1], dm_table_get_mode(ti->table), &dev);
1893 if (r) {
1894 DMWARN("message: error getting device %s",
1895 argv[1]);
1896 goto out;
1897 }
1898
1899 r = action_dev(m, dev, action);
1900
1901 dm_put_device(ti, dev);
1902
1903 out:
1904 mutex_unlock(&m->work_mutex);
1905 return r;
1906 }
1907
1908 static int multipath_prepare_ioctl(struct dm_target *ti,
1909 struct block_device **bdev, fmode_t *mode)
1910 {
1911 struct multipath *m = ti->private;
1912 struct pgpath *current_pgpath;
1913 int r;
1914
1915 current_pgpath = lockless_dereference(m->current_pgpath);
1916 if (!current_pgpath)
1917 current_pgpath = choose_pgpath(m, 0);
1918
1919 if (current_pgpath) {
1920 if (!test_bit(MPATHF_QUEUE_IO, &m->flags)) {
1921 *bdev = current_pgpath->path.dev->bdev;
1922 *mode = current_pgpath->path.dev->mode;
1923 r = 0;
1924 } else {
1925 /* pg_init has not started or completed */
1926 r = -ENOTCONN;
1927 }
1928 } else {
1929 /* No path is available */
1930 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
1931 r = -ENOTCONN;
1932 else
1933 r = -EIO;
1934 }
1935
1936 if (r == -ENOTCONN) {
1937 if (!lockless_dereference(m->current_pg)) {
1938 /* Path status changed, redo selection */
1939 (void) choose_pgpath(m, 0);
1940 }
1941 if (test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
1942 pg_init_all_paths(m);
1943 dm_table_run_md_queue_async(m->ti->table);
1944 process_queued_bios_list(m);
1945 }
1946
1947 /*
1948 * Only pass ioctls through if the device sizes match exactly.
1949 */
1950 if (!r && ti->len != i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT)
1951 return 1;
1952 return r;
1953 }
1954
1955 static int multipath_iterate_devices(struct dm_target *ti,
1956 iterate_devices_callout_fn fn, void *data)
1957 {
1958 struct multipath *m = ti->private;
1959 struct priority_group *pg;
1960 struct pgpath *p;
1961 int ret = 0;
1962
1963 list_for_each_entry(pg, &m->priority_groups, list) {
1964 list_for_each_entry(p, &pg->pgpaths, list) {
1965 ret = fn(ti, p->path.dev, ti->begin, ti->len, data);
1966 if (ret)
1967 goto out;
1968 }
1969 }
1970
1971 out:
1972 return ret;
1973 }
1974
1975 static int pgpath_busy(struct pgpath *pgpath)
1976 {
1977 struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
1978
1979 return blk_lld_busy(q);
1980 }
1981
1982 /*
1983 * We return "busy", only when we can map I/Os but underlying devices
1984 * are busy (so even if we map I/Os now, the I/Os will wait on
1985 * the underlying queue).
1986 * In other words, if we want to kill I/Os or queue them inside us
1987 * due to map unavailability, we don't return "busy". Otherwise,
1988 * dm core won't give us the I/Os and we can't do what we want.
1989 */
1990 static int multipath_busy(struct dm_target *ti)
1991 {
1992 bool busy = false, has_active = false;
1993 struct multipath *m = ti->private;
1994 struct priority_group *pg, *next_pg;
1995 struct pgpath *pgpath;
1996
1997 /* pg_init in progress or no paths available */
1998 if (atomic_read(&m->pg_init_in_progress) ||
1999 (!atomic_read(&m->nr_valid_paths) && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)))
2000 return true;
2001
2002 /* Guess which priority_group will be used at next mapping time */
2003 pg = lockless_dereference(m->current_pg);
2004 next_pg = lockless_dereference(m->next_pg);
2005 if (unlikely(!lockless_dereference(m->current_pgpath) && next_pg))
2006 pg = next_pg;
2007
2008 if (!pg) {
2009 /*
2010 * We don't know which pg will be used at next mapping time.
2011 * We don't call choose_pgpath() here to avoid to trigger
2012 * pg_init just by busy checking.
2013 * So we don't know whether underlying devices we will be using
2014 * at next mapping time are busy or not. Just try mapping.
2015 */
2016 return busy;
2017 }
2018
2019 /*
2020 * If there is one non-busy active path at least, the path selector
2021 * will be able to select it. So we consider such a pg as not busy.
2022 */
2023 busy = true;
2024 list_for_each_entry(pgpath, &pg->pgpaths, list) {
2025 if (pgpath->is_active) {
2026 has_active = true;
2027 if (!pgpath_busy(pgpath)) {
2028 busy = false;
2029 break;
2030 }
2031 }
2032 }
2033
2034 if (!has_active) {
2035 /*
2036 * No active path in this pg, so this pg won't be used and
2037 * the current_pg will be changed at next mapping time.
2038 * We need to try mapping to determine it.
2039 */
2040 busy = false;
2041 }
2042
2043 return busy;
2044 }
2045
2046 /*-----------------------------------------------------------------
2047 * Module setup
2048 *---------------------------------------------------------------*/
2049 static struct target_type multipath_target = {
2050 .name = "multipath",
2051 .version = {1, 12, 0},
2052 .features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE,
2053 .module = THIS_MODULE,
2054 .ctr = multipath_ctr,
2055 .dtr = multipath_dtr,
2056 .map_rq = multipath_map,
2057 .clone_and_map_rq = multipath_clone_and_map,
2058 .release_clone_rq = multipath_release_clone,
2059 .rq_end_io = multipath_end_io,
2060 .map = multipath_map_bio,
2061 .end_io = multipath_end_io_bio,
2062 .presuspend = multipath_presuspend,
2063 .postsuspend = multipath_postsuspend,
2064 .resume = multipath_resume,
2065 .status = multipath_status,
2066 .message = multipath_message,
2067 .prepare_ioctl = multipath_prepare_ioctl,
2068 .iterate_devices = multipath_iterate_devices,
2069 .busy = multipath_busy,
2070 };
2071
2072 static int __init dm_multipath_init(void)
2073 {
2074 int r;
2075
2076 /* allocate a slab for the dm_mpath_ios */
2077 _mpio_cache = KMEM_CACHE(dm_mpath_io, 0);
2078 if (!_mpio_cache)
2079 return -ENOMEM;
2080
2081 r = dm_register_target(&multipath_target);
2082 if (r < 0) {
2083 DMERR("request-based register failed %d", r);
2084 r = -EINVAL;
2085 goto bad_register_target;
2086 }
2087
2088 kmultipathd = alloc_workqueue("kmpathd", WQ_MEM_RECLAIM, 0);
2089 if (!kmultipathd) {
2090 DMERR("failed to create workqueue kmpathd");
2091 r = -ENOMEM;
2092 goto bad_alloc_kmultipathd;
2093 }
2094
2095 /*
2096 * A separate workqueue is used to handle the device handlers
2097 * to avoid overloading existing workqueue. Overloading the
2098 * old workqueue would also create a bottleneck in the
2099 * path of the storage hardware device activation.
2100 */
2101 kmpath_handlerd = alloc_ordered_workqueue("kmpath_handlerd",
2102 WQ_MEM_RECLAIM);
2103 if (!kmpath_handlerd) {
2104 DMERR("failed to create workqueue kmpath_handlerd");
2105 r = -ENOMEM;
2106 goto bad_alloc_kmpath_handlerd;
2107 }
2108
2109 return 0;
2110
2111 bad_alloc_kmpath_handlerd:
2112 destroy_workqueue(kmultipathd);
2113 bad_alloc_kmultipathd:
2114 dm_unregister_target(&multipath_target);
2115 bad_register_target:
2116 kmem_cache_destroy(_mpio_cache);
2117
2118 return r;
2119 }
2120
2121 static void __exit dm_multipath_exit(void)
2122 {
2123 destroy_workqueue(kmpath_handlerd);
2124 destroy_workqueue(kmultipathd);
2125
2126 dm_unregister_target(&multipath_target);
2127 kmem_cache_destroy(_mpio_cache);
2128 }
2129
2130 module_init(dm_multipath_init);
2131 module_exit(dm_multipath_exit);
2132
2133 MODULE_DESCRIPTION(DM_NAME " multipath target");
2134 MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
2135 MODULE_LICENSE("GPL");
Linux kernel - Deliverables
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