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Merge tag 'sound-fix-4.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai...
[GitHub/moto-9609/android_kernel_motorola_exynos9610.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 enum dm_queue_mode queue_mode;
94
95 struct mutex work_mutex;
96 struct work_struct trigger_event;
97
98 struct work_struct process_queued_bios;
99 struct bio_list queued_bios;
100 };
101
102 /*
103 * Context information attached to each io we process.
104 */
105 struct dm_mpath_io {
106 struct pgpath *pgpath;
107 size_t nr_bytes;
108 };
109
110 typedef int (*action_fn) (struct pgpath *pgpath);
111
112 static struct workqueue_struct *kmultipathd, *kmpath_handlerd;
113 static void trigger_event(struct work_struct *work);
114 static void activate_or_offline_path(struct pgpath *pgpath);
115 static void activate_path_work(struct work_struct *work);
116 static void process_queued_bios(struct work_struct *work);
117
118 /*-----------------------------------------------
119 * Multipath state flags.
120 *-----------------------------------------------*/
121
122 #define MPATHF_QUEUE_IO 0 /* Must we queue all I/O? */
123 #define MPATHF_QUEUE_IF_NO_PATH 1 /* Queue I/O if last path fails? */
124 #define MPATHF_SAVED_QUEUE_IF_NO_PATH 2 /* Saved state during suspension */
125 #define MPATHF_RETAIN_ATTACHED_HW_HANDLER 3 /* If there's already a hw_handler present, don't change it. */
126 #define MPATHF_PG_INIT_DISABLED 4 /* pg_init is not currently allowed */
127 #define MPATHF_PG_INIT_REQUIRED 5 /* pg_init needs calling? */
128 #define MPATHF_PG_INIT_DELAY_RETRY 6 /* Delay pg_init retry? */
129
130 /*-----------------------------------------------
131 * Allocation routines
132 *-----------------------------------------------*/
133
134 static struct pgpath *alloc_pgpath(void)
135 {
136 struct pgpath *pgpath = kzalloc(sizeof(*pgpath), GFP_KERNEL);
137
138 if (pgpath) {
139 pgpath->is_active = true;
140 INIT_DELAYED_WORK(&pgpath->activate_path, activate_path_work);
141 }
142
143 return pgpath;
144 }
145
146 static void free_pgpath(struct pgpath *pgpath)
147 {
148 kfree(pgpath);
149 }
150
151 static struct priority_group *alloc_priority_group(void)
152 {
153 struct priority_group *pg;
154
155 pg = kzalloc(sizeof(*pg), GFP_KERNEL);
156
157 if (pg)
158 INIT_LIST_HEAD(&pg->pgpaths);
159
160 return pg;
161 }
162
163 static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti)
164 {
165 struct pgpath *pgpath, *tmp;
166
167 list_for_each_entry_safe(pgpath, tmp, pgpaths, list) {
168 list_del(&pgpath->list);
169 dm_put_device(ti, pgpath->path.dev);
170 free_pgpath(pgpath);
171 }
172 }
173
174 static void free_priority_group(struct priority_group *pg,
175 struct dm_target *ti)
176 {
177 struct path_selector *ps = &pg->ps;
178
179 if (ps->type) {
180 ps->type->destroy(ps);
181 dm_put_path_selector(ps->type);
182 }
183
184 free_pgpaths(&pg->pgpaths, ti);
185 kfree(pg);
186 }
187
188 static struct multipath *alloc_multipath(struct dm_target *ti)
189 {
190 struct multipath *m;
191
192 m = kzalloc(sizeof(*m), GFP_KERNEL);
193 if (m) {
194 INIT_LIST_HEAD(&m->priority_groups);
195 spin_lock_init(&m->lock);
196 set_bit(MPATHF_QUEUE_IO, &m->flags);
197 atomic_set(&m->nr_valid_paths, 0);
198 atomic_set(&m->pg_init_in_progress, 0);
199 atomic_set(&m->pg_init_count, 0);
200 m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT;
201 INIT_WORK(&m->trigger_event, trigger_event);
202 init_waitqueue_head(&m->pg_init_wait);
203 mutex_init(&m->work_mutex);
204
205 m->queue_mode = DM_TYPE_NONE;
206
207 m->ti = ti;
208 ti->private = m;
209 }
210
211 return m;
212 }
213
214 static int alloc_multipath_stage2(struct dm_target *ti, struct multipath *m)
215 {
216 if (m->queue_mode == DM_TYPE_NONE) {
217 /*
218 * Default to request-based.
219 */
220 if (dm_use_blk_mq(dm_table_get_md(ti->table)))
221 m->queue_mode = DM_TYPE_MQ_REQUEST_BASED;
222 else
223 m->queue_mode = DM_TYPE_REQUEST_BASED;
224 } else if (m->queue_mode == DM_TYPE_BIO_BASED) {
225 INIT_WORK(&m->process_queued_bios, process_queued_bios);
226 /*
227 * bio-based doesn't support any direct scsi_dh management;
228 * it just discovers if a scsi_dh is attached.
229 */
230 set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags);
231 }
232
233 dm_table_set_type(ti->table, m->queue_mode);
234
235 return 0;
236 }
237
238 static void free_multipath(struct multipath *m)
239 {
240 struct priority_group *pg, *tmp;
241
242 list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) {
243 list_del(&pg->list);
244 free_priority_group(pg, m->ti);
245 }
246
247 kfree(m->hw_handler_name);
248 kfree(m->hw_handler_params);
249 kfree(m);
250 }
251
252 static struct dm_mpath_io *get_mpio(union map_info *info)
253 {
254 return info->ptr;
255 }
256
257 static size_t multipath_per_bio_data_size(void)
258 {
259 return sizeof(struct dm_mpath_io) + sizeof(struct dm_bio_details);
260 }
261
262 static struct dm_mpath_io *get_mpio_from_bio(struct bio *bio)
263 {
264 return dm_per_bio_data(bio, multipath_per_bio_data_size());
265 }
266
267 static struct dm_bio_details *get_bio_details_from_bio(struct bio *bio)
268 {
269 /* dm_bio_details is immediately after the dm_mpath_io in bio's per-bio-data */
270 struct dm_mpath_io *mpio = get_mpio_from_bio(bio);
271 void *bio_details = mpio + 1;
272
273 return bio_details;
274 }
275
276 static void multipath_init_per_bio_data(struct bio *bio, struct dm_mpath_io **mpio_p,
277 struct dm_bio_details **bio_details_p)
278 {
279 struct dm_mpath_io *mpio = get_mpio_from_bio(bio);
280 struct dm_bio_details *bio_details = get_bio_details_from_bio(bio);
281
282 memset(mpio, 0, sizeof(*mpio));
283 memset(bio_details, 0, sizeof(*bio_details));
284 dm_bio_record(bio_details, bio);
285
286 if (mpio_p)
287 *mpio_p = mpio;
288 if (bio_details_p)
289 *bio_details_p = bio_details;
290 }
291
292 /*-----------------------------------------------
293 * Path selection
294 *-----------------------------------------------*/
295
296 static int __pg_init_all_paths(struct multipath *m)
297 {
298 struct pgpath *pgpath;
299 unsigned long pg_init_delay = 0;
300
301 lockdep_assert_held(&m->lock);
302
303 if (atomic_read(&m->pg_init_in_progress) || test_bit(MPATHF_PG_INIT_DISABLED, &m->flags))
304 return 0;
305
306 atomic_inc(&m->pg_init_count);
307 clear_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
308
309 /* Check here to reset pg_init_required */
310 if (!m->current_pg)
311 return 0;
312
313 if (test_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags))
314 pg_init_delay = msecs_to_jiffies(m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT ?
315 m->pg_init_delay_msecs : DM_PG_INIT_DELAY_MSECS);
316 list_for_each_entry(pgpath, &m->current_pg->pgpaths, list) {
317 /* Skip failed paths */
318 if (!pgpath->is_active)
319 continue;
320 if (queue_delayed_work(kmpath_handlerd, &pgpath->activate_path,
321 pg_init_delay))
322 atomic_inc(&m->pg_init_in_progress);
323 }
324 return atomic_read(&m->pg_init_in_progress);
325 }
326
327 static int pg_init_all_paths(struct multipath *m)
328 {
329 int ret;
330 unsigned long flags;
331
332 spin_lock_irqsave(&m->lock, flags);
333 ret = __pg_init_all_paths(m);
334 spin_unlock_irqrestore(&m->lock, flags);
335
336 return ret;
337 }
338
339 static void __switch_pg(struct multipath *m, struct priority_group *pg)
340 {
341 m->current_pg = pg;
342
343 /* Must we initialise the PG first, and queue I/O till it's ready? */
344 if (m->hw_handler_name) {
345 set_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
346 set_bit(MPATHF_QUEUE_IO, &m->flags);
347 } else {
348 clear_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
349 clear_bit(MPATHF_QUEUE_IO, &m->flags);
350 }
351
352 atomic_set(&m->pg_init_count, 0);
353 }
354
355 static struct pgpath *choose_path_in_pg(struct multipath *m,
356 struct priority_group *pg,
357 size_t nr_bytes)
358 {
359 unsigned long flags;
360 struct dm_path *path;
361 struct pgpath *pgpath;
362
363 path = pg->ps.type->select_path(&pg->ps, nr_bytes);
364 if (!path)
365 return ERR_PTR(-ENXIO);
366
367 pgpath = path_to_pgpath(path);
368
369 if (unlikely(lockless_dereference(m->current_pg) != pg)) {
370 /* Only update current_pgpath if pg changed */
371 spin_lock_irqsave(&m->lock, flags);
372 m->current_pgpath = pgpath;
373 __switch_pg(m, pg);
374 spin_unlock_irqrestore(&m->lock, flags);
375 }
376
377 return pgpath;
378 }
379
380 static struct pgpath *choose_pgpath(struct multipath *m, size_t nr_bytes)
381 {
382 unsigned long flags;
383 struct priority_group *pg;
384 struct pgpath *pgpath;
385 unsigned bypassed = 1;
386
387 if (!atomic_read(&m->nr_valid_paths)) {
388 clear_bit(MPATHF_QUEUE_IO, &m->flags);
389 goto failed;
390 }
391
392 /* Were we instructed to switch PG? */
393 if (lockless_dereference(m->next_pg)) {
394 spin_lock_irqsave(&m->lock, flags);
395 pg = m->next_pg;
396 if (!pg) {
397 spin_unlock_irqrestore(&m->lock, flags);
398 goto check_current_pg;
399 }
400 m->next_pg = NULL;
401 spin_unlock_irqrestore(&m->lock, flags);
402 pgpath = choose_path_in_pg(m, pg, nr_bytes);
403 if (!IS_ERR_OR_NULL(pgpath))
404 return pgpath;
405 }
406
407 /* Don't change PG until it has no remaining paths */
408 check_current_pg:
409 pg = lockless_dereference(m->current_pg);
410 if (pg) {
411 pgpath = choose_path_in_pg(m, pg, nr_bytes);
412 if (!IS_ERR_OR_NULL(pgpath))
413 return pgpath;
414 }
415
416 /*
417 * Loop through priority groups until we find a valid path.
418 * First time we skip PGs marked 'bypassed'.
419 * Second time we only try the ones we skipped, but set
420 * pg_init_delay_retry so we do not hammer controllers.
421 */
422 do {
423 list_for_each_entry(pg, &m->priority_groups, list) {
424 if (pg->bypassed == !!bypassed)
425 continue;
426 pgpath = choose_path_in_pg(m, pg, nr_bytes);
427 if (!IS_ERR_OR_NULL(pgpath)) {
428 if (!bypassed)
429 set_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
430 return pgpath;
431 }
432 }
433 } while (bypassed--);
434
435 failed:
436 spin_lock_irqsave(&m->lock, flags);
437 m->current_pgpath = NULL;
438 m->current_pg = NULL;
439 spin_unlock_irqrestore(&m->lock, flags);
440
441 return NULL;
442 }
443
444 /*
445 * dm_report_EIO() is a macro instead of a function to make pr_debug()
446 * report the function name and line number of the function from which
447 * it has been invoked.
448 */
449 #define dm_report_EIO(m) \
450 do { \
451 struct mapped_device *md = dm_table_get_md((m)->ti->table); \
452 \
453 pr_debug("%s: returning EIO; QIFNP = %d; SQIFNP = %d; DNFS = %d\n", \
454 dm_device_name(md), \
455 test_bit(MPATHF_QUEUE_IF_NO_PATH, &(m)->flags), \
456 test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &(m)->flags), \
457 dm_noflush_suspending((m)->ti)); \
458 } while (0)
459
460 /*
461 * Map cloned requests (request-based multipath)
462 */
463 static int multipath_clone_and_map(struct dm_target *ti, struct request *rq,
464 union map_info *map_context,
465 struct request **__clone)
466 {
467 struct multipath *m = ti->private;
468 size_t nr_bytes = blk_rq_bytes(rq);
469 struct pgpath *pgpath;
470 struct block_device *bdev;
471 struct dm_mpath_io *mpio = get_mpio(map_context);
472 struct request_queue *q;
473 struct request *clone;
474
475 /* Do we need to select a new pgpath? */
476 pgpath = lockless_dereference(m->current_pgpath);
477 if (!pgpath || !test_bit(MPATHF_QUEUE_IO, &m->flags))
478 pgpath = choose_pgpath(m, nr_bytes);
479
480 if (!pgpath) {
481 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
482 return DM_MAPIO_DELAY_REQUEUE;
483 dm_report_EIO(m); /* Failed */
484 return DM_MAPIO_KILL;
485 } else if (test_bit(MPATHF_QUEUE_IO, &m->flags) ||
486 test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags)) {
487 if (pg_init_all_paths(m))
488 return DM_MAPIO_DELAY_REQUEUE;
489 return DM_MAPIO_REQUEUE;
490 }
491
492 memset(mpio, 0, sizeof(*mpio));
493 mpio->pgpath = pgpath;
494 mpio->nr_bytes = nr_bytes;
495
496 bdev = pgpath->path.dev->bdev;
497 q = bdev_get_queue(bdev);
498 clone = blk_get_request(q, rq->cmd_flags | REQ_NOMERGE, GFP_ATOMIC);
499 if (IS_ERR(clone)) {
500 /* EBUSY, ENODEV or EWOULDBLOCK: requeue */
501 bool queue_dying = blk_queue_dying(q);
502 DMERR_LIMIT("blk_get_request() returned %ld%s - requeuing",
503 PTR_ERR(clone), queue_dying ? " (path offline)" : "");
504 if (queue_dying) {
505 atomic_inc(&m->pg_init_in_progress);
506 activate_or_offline_path(pgpath);
507 }
508 return DM_MAPIO_DELAY_REQUEUE;
509 }
510 clone->bio = clone->biotail = NULL;
511 clone->rq_disk = bdev->bd_disk;
512 clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
513 *__clone = clone;
514
515 if (pgpath->pg->ps.type->start_io)
516 pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
517 &pgpath->path,
518 nr_bytes);
519 return DM_MAPIO_REMAPPED;
520 }
521
522 static void multipath_release_clone(struct request *clone)
523 {
524 blk_put_request(clone);
525 }
526
527 /*
528 * Map cloned bios (bio-based multipath)
529 */
530 static int __multipath_map_bio(struct multipath *m, struct bio *bio, struct dm_mpath_io *mpio)
531 {
532 size_t nr_bytes = bio->bi_iter.bi_size;
533 struct pgpath *pgpath;
534 unsigned long flags;
535 bool queue_io;
536
537 /* Do we need to select a new pgpath? */
538 pgpath = lockless_dereference(m->current_pgpath);
539 queue_io = test_bit(MPATHF_QUEUE_IO, &m->flags);
540 if (!pgpath || !queue_io)
541 pgpath = choose_pgpath(m, nr_bytes);
542
543 if ((pgpath && queue_io) ||
544 (!pgpath && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))) {
545 /* Queue for the daemon to resubmit */
546 spin_lock_irqsave(&m->lock, flags);
547 bio_list_add(&m->queued_bios, bio);
548 spin_unlock_irqrestore(&m->lock, flags);
549 /* PG_INIT_REQUIRED cannot be set without QUEUE_IO */
550 if (queue_io || test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
551 pg_init_all_paths(m);
552 else if (!queue_io)
553 queue_work(kmultipathd, &m->process_queued_bios);
554 return DM_MAPIO_SUBMITTED;
555 }
556
557 if (!pgpath) {
558 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
559 return DM_MAPIO_REQUEUE;
560 dm_report_EIO(m);
561 return DM_MAPIO_KILL;
562 }
563
564 mpio->pgpath = pgpath;
565 mpio->nr_bytes = nr_bytes;
566
567 bio->bi_status = 0;
568 bio_set_dev(bio, pgpath->path.dev->bdev);
569 bio->bi_opf |= REQ_FAILFAST_TRANSPORT;
570
571 if (pgpath->pg->ps.type->start_io)
572 pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
573 &pgpath->path,
574 nr_bytes);
575 return DM_MAPIO_REMAPPED;
576 }
577
578 static int multipath_map_bio(struct dm_target *ti, struct bio *bio)
579 {
580 struct multipath *m = ti->private;
581 struct dm_mpath_io *mpio = NULL;
582
583 multipath_init_per_bio_data(bio, &mpio, NULL);
584
585 return __multipath_map_bio(m, bio, mpio);
586 }
587
588 static void process_queued_io_list(struct multipath *m)
589 {
590 if (m->queue_mode == DM_TYPE_MQ_REQUEST_BASED)
591 dm_mq_kick_requeue_list(dm_table_get_md(m->ti->table));
592 else if (m->queue_mode == DM_TYPE_BIO_BASED)
593 queue_work(kmultipathd, &m->process_queued_bios);
594 }
595
596 static void process_queued_bios(struct work_struct *work)
597 {
598 int r;
599 unsigned long flags;
600 struct bio *bio;
601 struct bio_list bios;
602 struct blk_plug plug;
603 struct multipath *m =
604 container_of(work, struct multipath, process_queued_bios);
605
606 bio_list_init(&bios);
607
608 spin_lock_irqsave(&m->lock, flags);
609
610 if (bio_list_empty(&m->queued_bios)) {
611 spin_unlock_irqrestore(&m->lock, flags);
612 return;
613 }
614
615 bio_list_merge(&bios, &m->queued_bios);
616 bio_list_init(&m->queued_bios);
617
618 spin_unlock_irqrestore(&m->lock, flags);
619
620 blk_start_plug(&plug);
621 while ((bio = bio_list_pop(&bios))) {
622 r = __multipath_map_bio(m, bio, get_mpio_from_bio(bio));
623 switch (r) {
624 case DM_MAPIO_KILL:
625 bio->bi_status = BLK_STS_IOERR;
626 bio_endio(bio);
627 break;
628 case DM_MAPIO_REQUEUE:
629 bio->bi_status = BLK_STS_DM_REQUEUE;
630 bio_endio(bio);
631 break;
632 case DM_MAPIO_REMAPPED:
633 generic_make_request(bio);
634 break;
635 }
636 }
637 blk_finish_plug(&plug);
638 }
639
640 static void assign_bit(bool value, long nr, unsigned long *addr)
641 {
642 if (value)
643 set_bit(nr, addr);
644 else
645 clear_bit(nr, addr);
646 }
647
648 /*
649 * If we run out of usable paths, should we queue I/O or error it?
650 */
651 static int queue_if_no_path(struct multipath *m, bool queue_if_no_path,
652 bool save_old_value)
653 {
654 unsigned long flags;
655
656 spin_lock_irqsave(&m->lock, flags);
657 assign_bit((save_old_value && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) ||
658 (!save_old_value && queue_if_no_path),
659 MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
660 assign_bit(queue_if_no_path || dm_noflush_suspending(m->ti),
661 MPATHF_QUEUE_IF_NO_PATH, &m->flags);
662 spin_unlock_irqrestore(&m->lock, flags);
663
664 if (!queue_if_no_path) {
665 dm_table_run_md_queue_async(m->ti->table);
666 process_queued_io_list(m);
667 }
668
669 return 0;
670 }
671
672 /*
673 * An event is triggered whenever a path is taken out of use.
674 * Includes path failure and PG bypass.
675 */
676 static void trigger_event(struct work_struct *work)
677 {
678 struct multipath *m =
679 container_of(work, struct multipath, trigger_event);
680
681 dm_table_event(m->ti->table);
682 }
683
684 /*-----------------------------------------------------------------
685 * Constructor/argument parsing:
686 * <#multipath feature args> [<arg>]*
687 * <#hw_handler args> [hw_handler [<arg>]*]
688 * <#priority groups>
689 * <initial priority group>
690 * [<selector> <#selector args> [<arg>]*
691 * <#paths> <#per-path selector args>
692 * [<path> [<arg>]* ]+ ]+
693 *---------------------------------------------------------------*/
694 static int parse_path_selector(struct dm_arg_set *as, struct priority_group *pg,
695 struct dm_target *ti)
696 {
697 int r;
698 struct path_selector_type *pst;
699 unsigned ps_argc;
700
701 static struct dm_arg _args[] = {
702 {0, 1024, "invalid number of path selector args"},
703 };
704
705 pst = dm_get_path_selector(dm_shift_arg(as));
706 if (!pst) {
707 ti->error = "unknown path selector type";
708 return -EINVAL;
709 }
710
711 r = dm_read_arg_group(_args, as, &ps_argc, &ti->error);
712 if (r) {
713 dm_put_path_selector(pst);
714 return -EINVAL;
715 }
716
717 r = pst->create(&pg->ps, ps_argc, as->argv);
718 if (r) {
719 dm_put_path_selector(pst);
720 ti->error = "path selector constructor failed";
721 return r;
722 }
723
724 pg->ps.type = pst;
725 dm_consume_args(as, ps_argc);
726
727 return 0;
728 }
729
730 static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps,
731 struct dm_target *ti)
732 {
733 int r;
734 struct pgpath *p;
735 struct multipath *m = ti->private;
736 struct request_queue *q = NULL;
737 const char *attached_handler_name;
738
739 /* we need at least a path arg */
740 if (as->argc < 1) {
741 ti->error = "no device given";
742 return ERR_PTR(-EINVAL);
743 }
744
745 p = alloc_pgpath();
746 if (!p)
747 return ERR_PTR(-ENOMEM);
748
749 r = dm_get_device(ti, dm_shift_arg(as), dm_table_get_mode(ti->table),
750 &p->path.dev);
751 if (r) {
752 ti->error = "error getting device";
753 goto bad;
754 }
755
756 if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags) || m->hw_handler_name)
757 q = bdev_get_queue(p->path.dev->bdev);
758
759 if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags)) {
760 retain:
761 attached_handler_name = scsi_dh_attached_handler_name(q, GFP_KERNEL);
762 if (attached_handler_name) {
763 /*
764 * Clear any hw_handler_params associated with a
765 * handler that isn't already attached.
766 */
767 if (m->hw_handler_name && strcmp(attached_handler_name, m->hw_handler_name)) {
768 kfree(m->hw_handler_params);
769 m->hw_handler_params = NULL;
770 }
771
772 /*
773 * Reset hw_handler_name to match the attached handler
774 *
775 * NB. This modifies the table line to show the actual
776 * handler instead of the original table passed in.
777 */
778 kfree(m->hw_handler_name);
779 m->hw_handler_name = attached_handler_name;
780 }
781 }
782
783 if (m->hw_handler_name) {
784 r = scsi_dh_attach(q, m->hw_handler_name);
785 if (r == -EBUSY) {
786 char b[BDEVNAME_SIZE];
787
788 printk(KERN_INFO "dm-mpath: retaining handler on device %s\n",
789 bdevname(p->path.dev->bdev, b));
790 goto retain;
791 }
792 if (r < 0) {
793 ti->error = "error attaching hardware handler";
794 dm_put_device(ti, p->path.dev);
795 goto bad;
796 }
797
798 if (m->hw_handler_params) {
799 r = scsi_dh_set_params(q, m->hw_handler_params);
800 if (r < 0) {
801 ti->error = "unable to set hardware "
802 "handler parameters";
803 dm_put_device(ti, p->path.dev);
804 goto bad;
805 }
806 }
807 }
808
809 r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
810 if (r) {
811 dm_put_device(ti, p->path.dev);
812 goto bad;
813 }
814
815 return p;
816
817 bad:
818 free_pgpath(p);
819 return ERR_PTR(r);
820 }
821
822 static struct priority_group *parse_priority_group(struct dm_arg_set *as,
823 struct multipath *m)
824 {
825 static struct dm_arg _args[] = {
826 {1, 1024, "invalid number of paths"},
827 {0, 1024, "invalid number of selector args"}
828 };
829
830 int r;
831 unsigned i, nr_selector_args, nr_args;
832 struct priority_group *pg;
833 struct dm_target *ti = m->ti;
834
835 if (as->argc < 2) {
836 as->argc = 0;
837 ti->error = "not enough priority group arguments";
838 return ERR_PTR(-EINVAL);
839 }
840
841 pg = alloc_priority_group();
842 if (!pg) {
843 ti->error = "couldn't allocate priority group";
844 return ERR_PTR(-ENOMEM);
845 }
846 pg->m = m;
847
848 r = parse_path_selector(as, pg, ti);
849 if (r)
850 goto bad;
851
852 /*
853 * read the paths
854 */
855 r = dm_read_arg(_args, as, &pg->nr_pgpaths, &ti->error);
856 if (r)
857 goto bad;
858
859 r = dm_read_arg(_args + 1, as, &nr_selector_args, &ti->error);
860 if (r)
861 goto bad;
862
863 nr_args = 1 + nr_selector_args;
864 for (i = 0; i < pg->nr_pgpaths; i++) {
865 struct pgpath *pgpath;
866 struct dm_arg_set path_args;
867
868 if (as->argc < nr_args) {
869 ti->error = "not enough path parameters";
870 r = -EINVAL;
871 goto bad;
872 }
873
874 path_args.argc = nr_args;
875 path_args.argv = as->argv;
876
877 pgpath = parse_path(&path_args, &pg->ps, ti);
878 if (IS_ERR(pgpath)) {
879 r = PTR_ERR(pgpath);
880 goto bad;
881 }
882
883 pgpath->pg = pg;
884 list_add_tail(&pgpath->list, &pg->pgpaths);
885 dm_consume_args(as, nr_args);
886 }
887
888 return pg;
889
890 bad:
891 free_priority_group(pg, ti);
892 return ERR_PTR(r);
893 }
894
895 static int parse_hw_handler(struct dm_arg_set *as, struct multipath *m)
896 {
897 unsigned hw_argc;
898 int ret;
899 struct dm_target *ti = m->ti;
900
901 static struct dm_arg _args[] = {
902 {0, 1024, "invalid number of hardware handler args"},
903 };
904
905 if (dm_read_arg_group(_args, as, &hw_argc, &ti->error))
906 return -EINVAL;
907
908 if (!hw_argc)
909 return 0;
910
911 if (m->queue_mode == DM_TYPE_BIO_BASED) {
912 dm_consume_args(as, hw_argc);
913 DMERR("bio-based multipath doesn't allow hardware handler args");
914 return 0;
915 }
916
917 m->hw_handler_name = kstrdup(dm_shift_arg(as), GFP_KERNEL);
918 if (!m->hw_handler_name)
919 return -EINVAL;
920
921 if (hw_argc > 1) {
922 char *p;
923 int i, j, len = 4;
924
925 for (i = 0; i <= hw_argc - 2; i++)
926 len += strlen(as->argv[i]) + 1;
927 p = m->hw_handler_params = kzalloc(len, GFP_KERNEL);
928 if (!p) {
929 ti->error = "memory allocation failed";
930 ret = -ENOMEM;
931 goto fail;
932 }
933 j = sprintf(p, "%d", hw_argc - 1);
934 for (i = 0, p+=j+1; i <= hw_argc - 2; i++, p+=j+1)
935 j = sprintf(p, "%s", as->argv[i]);
936 }
937 dm_consume_args(as, hw_argc - 1);
938
939 return 0;
940 fail:
941 kfree(m->hw_handler_name);
942 m->hw_handler_name = NULL;
943 return ret;
944 }
945
946 static int parse_features(struct dm_arg_set *as, struct multipath *m)
947 {
948 int r;
949 unsigned argc;
950 struct dm_target *ti = m->ti;
951 const char *arg_name;
952
953 static struct dm_arg _args[] = {
954 {0, 8, "invalid number of feature args"},
955 {1, 50, "pg_init_retries must be between 1 and 50"},
956 {0, 60000, "pg_init_delay_msecs must be between 0 and 60000"},
957 };
958
959 r = dm_read_arg_group(_args, as, &argc, &ti->error);
960 if (r)
961 return -EINVAL;
962
963 if (!argc)
964 return 0;
965
966 do {
967 arg_name = dm_shift_arg(as);
968 argc--;
969
970 if (!strcasecmp(arg_name, "queue_if_no_path")) {
971 r = queue_if_no_path(m, true, false);
972 continue;
973 }
974
975 if (!strcasecmp(arg_name, "retain_attached_hw_handler")) {
976 set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags);
977 continue;
978 }
979
980 if (!strcasecmp(arg_name, "pg_init_retries") &&
981 (argc >= 1)) {
982 r = dm_read_arg(_args + 1, as, &m->pg_init_retries, &ti->error);
983 argc--;
984 continue;
985 }
986
987 if (!strcasecmp(arg_name, "pg_init_delay_msecs") &&
988 (argc >= 1)) {
989 r = dm_read_arg(_args + 2, as, &m->pg_init_delay_msecs, &ti->error);
990 argc--;
991 continue;
992 }
993
994 if (!strcasecmp(arg_name, "queue_mode") &&
995 (argc >= 1)) {
996 const char *queue_mode_name = dm_shift_arg(as);
997
998 if (!strcasecmp(queue_mode_name, "bio"))
999 m->queue_mode = DM_TYPE_BIO_BASED;
1000 else if (!strcasecmp(queue_mode_name, "rq"))
1001 m->queue_mode = DM_TYPE_REQUEST_BASED;
1002 else if (!strcasecmp(queue_mode_name, "mq"))
1003 m->queue_mode = DM_TYPE_MQ_REQUEST_BASED;
1004 else {
1005 ti->error = "Unknown 'queue_mode' requested";
1006 r = -EINVAL;
1007 }
1008 argc--;
1009 continue;
1010 }
1011
1012 ti->error = "Unrecognised multipath feature request";
1013 r = -EINVAL;
1014 } while (argc && !r);
1015
1016 return r;
1017 }
1018
1019 static int multipath_ctr(struct dm_target *ti, unsigned argc, char **argv)
1020 {
1021 /* target arguments */
1022 static struct dm_arg _args[] = {
1023 {0, 1024, "invalid number of priority groups"},
1024 {0, 1024, "invalid initial priority group number"},
1025 };
1026
1027 int r;
1028 struct multipath *m;
1029 struct dm_arg_set as;
1030 unsigned pg_count = 0;
1031 unsigned next_pg_num;
1032
1033 as.argc = argc;
1034 as.argv = argv;
1035
1036 m = alloc_multipath(ti);
1037 if (!m) {
1038 ti->error = "can't allocate multipath";
1039 return -EINVAL;
1040 }
1041
1042 r = parse_features(&as, m);
1043 if (r)
1044 goto bad;
1045
1046 r = alloc_multipath_stage2(ti, m);
1047 if (r)
1048 goto bad;
1049
1050 r = parse_hw_handler(&as, m);
1051 if (r)
1052 goto bad;
1053
1054 r = dm_read_arg(_args, &as, &m->nr_priority_groups, &ti->error);
1055 if (r)
1056 goto bad;
1057
1058 r = dm_read_arg(_args + 1, &as, &next_pg_num, &ti->error);
1059 if (r)
1060 goto bad;
1061
1062 if ((!m->nr_priority_groups && next_pg_num) ||
1063 (m->nr_priority_groups && !next_pg_num)) {
1064 ti->error = "invalid initial priority group";
1065 r = -EINVAL;
1066 goto bad;
1067 }
1068
1069 /* parse the priority groups */
1070 while (as.argc) {
1071 struct priority_group *pg;
1072 unsigned nr_valid_paths = atomic_read(&m->nr_valid_paths);
1073
1074 pg = parse_priority_group(&as, m);
1075 if (IS_ERR(pg)) {
1076 r = PTR_ERR(pg);
1077 goto bad;
1078 }
1079
1080 nr_valid_paths += pg->nr_pgpaths;
1081 atomic_set(&m->nr_valid_paths, nr_valid_paths);
1082
1083 list_add_tail(&pg->list, &m->priority_groups);
1084 pg_count++;
1085 pg->pg_num = pg_count;
1086 if (!--next_pg_num)
1087 m->next_pg = pg;
1088 }
1089
1090 if (pg_count != m->nr_priority_groups) {
1091 ti->error = "priority group count mismatch";
1092 r = -EINVAL;
1093 goto bad;
1094 }
1095
1096 ti->num_flush_bios = 1;
1097 ti->num_discard_bios = 1;
1098 ti->num_write_same_bios = 1;
1099 ti->num_write_zeroes_bios = 1;
1100 if (m->queue_mode == DM_TYPE_BIO_BASED)
1101 ti->per_io_data_size = multipath_per_bio_data_size();
1102 else
1103 ti->per_io_data_size = sizeof(struct dm_mpath_io);
1104
1105 return 0;
1106
1107 bad:
1108 free_multipath(m);
1109 return r;
1110 }
1111
1112 static void multipath_wait_for_pg_init_completion(struct multipath *m)
1113 {
1114 DEFINE_WAIT(wait);
1115
1116 while (1) {
1117 prepare_to_wait(&m->pg_init_wait, &wait, TASK_UNINTERRUPTIBLE);
1118
1119 if (!atomic_read(&m->pg_init_in_progress))
1120 break;
1121
1122 io_schedule();
1123 }
1124 finish_wait(&m->pg_init_wait, &wait);
1125 }
1126
1127 static void flush_multipath_work(struct multipath *m)
1128 {
1129 set_bit(MPATHF_PG_INIT_DISABLED, &m->flags);
1130 smp_mb__after_atomic();
1131
1132 flush_workqueue(kmpath_handlerd);
1133 multipath_wait_for_pg_init_completion(m);
1134 flush_workqueue(kmultipathd);
1135 flush_work(&m->trigger_event);
1136
1137 clear_bit(MPATHF_PG_INIT_DISABLED, &m->flags);
1138 smp_mb__after_atomic();
1139 }
1140
1141 static void multipath_dtr(struct dm_target *ti)
1142 {
1143 struct multipath *m = ti->private;
1144
1145 flush_multipath_work(m);
1146 free_multipath(m);
1147 }
1148
1149 /*
1150 * Take a path out of use.
1151 */
1152 static int fail_path(struct pgpath *pgpath)
1153 {
1154 unsigned long flags;
1155 struct multipath *m = pgpath->pg->m;
1156
1157 spin_lock_irqsave(&m->lock, flags);
1158
1159 if (!pgpath->is_active)
1160 goto out;
1161
1162 DMWARN("Failing path %s.", pgpath->path.dev->name);
1163
1164 pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
1165 pgpath->is_active = false;
1166 pgpath->fail_count++;
1167
1168 atomic_dec(&m->nr_valid_paths);
1169
1170 if (pgpath == m->current_pgpath)
1171 m->current_pgpath = NULL;
1172
1173 dm_path_uevent(DM_UEVENT_PATH_FAILED, m->ti,
1174 pgpath->path.dev->name, atomic_read(&m->nr_valid_paths));
1175
1176 schedule_work(&m->trigger_event);
1177
1178 out:
1179 spin_unlock_irqrestore(&m->lock, flags);
1180
1181 return 0;
1182 }
1183
1184 /*
1185 * Reinstate a previously-failed path
1186 */
1187 static int reinstate_path(struct pgpath *pgpath)
1188 {
1189 int r = 0, run_queue = 0;
1190 unsigned long flags;
1191 struct multipath *m = pgpath->pg->m;
1192 unsigned nr_valid_paths;
1193
1194 spin_lock_irqsave(&m->lock, flags);
1195
1196 if (pgpath->is_active)
1197 goto out;
1198
1199 DMWARN("Reinstating path %s.", pgpath->path.dev->name);
1200
1201 r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
1202 if (r)
1203 goto out;
1204
1205 pgpath->is_active = true;
1206
1207 nr_valid_paths = atomic_inc_return(&m->nr_valid_paths);
1208 if (nr_valid_paths == 1) {
1209 m->current_pgpath = NULL;
1210 run_queue = 1;
1211 } else if (m->hw_handler_name && (m->current_pg == pgpath->pg)) {
1212 if (queue_work(kmpath_handlerd, &pgpath->activate_path.work))
1213 atomic_inc(&m->pg_init_in_progress);
1214 }
1215
1216 dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti,
1217 pgpath->path.dev->name, nr_valid_paths);
1218
1219 schedule_work(&m->trigger_event);
1220
1221 out:
1222 spin_unlock_irqrestore(&m->lock, flags);
1223 if (run_queue) {
1224 dm_table_run_md_queue_async(m->ti->table);
1225 process_queued_io_list(m);
1226 }
1227
1228 return r;
1229 }
1230
1231 /*
1232 * Fail or reinstate all paths that match the provided struct dm_dev.
1233 */
1234 static int action_dev(struct multipath *m, struct dm_dev *dev,
1235 action_fn action)
1236 {
1237 int r = -EINVAL;
1238 struct pgpath *pgpath;
1239 struct priority_group *pg;
1240
1241 list_for_each_entry(pg, &m->priority_groups, list) {
1242 list_for_each_entry(pgpath, &pg->pgpaths, list) {
1243 if (pgpath->path.dev == dev)
1244 r = action(pgpath);
1245 }
1246 }
1247
1248 return r;
1249 }
1250
1251 /*
1252 * Temporarily try to avoid having to use the specified PG
1253 */
1254 static void bypass_pg(struct multipath *m, struct priority_group *pg,
1255 bool bypassed)
1256 {
1257 unsigned long flags;
1258
1259 spin_lock_irqsave(&m->lock, flags);
1260
1261 pg->bypassed = bypassed;
1262 m->current_pgpath = NULL;
1263 m->current_pg = NULL;
1264
1265 spin_unlock_irqrestore(&m->lock, flags);
1266
1267 schedule_work(&m->trigger_event);
1268 }
1269
1270 /*
1271 * Switch to using the specified PG from the next I/O that gets mapped
1272 */
1273 static int switch_pg_num(struct multipath *m, const char *pgstr)
1274 {
1275 struct priority_group *pg;
1276 unsigned pgnum;
1277 unsigned long flags;
1278 char dummy;
1279
1280 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1281 !m->nr_priority_groups || (pgnum > m->nr_priority_groups)) {
1282 DMWARN("invalid PG number supplied to switch_pg_num");
1283 return -EINVAL;
1284 }
1285
1286 spin_lock_irqsave(&m->lock, flags);
1287 list_for_each_entry(pg, &m->priority_groups, list) {
1288 pg->bypassed = false;
1289 if (--pgnum)
1290 continue;
1291
1292 m->current_pgpath = NULL;
1293 m->current_pg = NULL;
1294 m->next_pg = pg;
1295 }
1296 spin_unlock_irqrestore(&m->lock, flags);
1297
1298 schedule_work(&m->trigger_event);
1299 return 0;
1300 }
1301
1302 /*
1303 * Set/clear bypassed status of a PG.
1304 * PGs are numbered upwards from 1 in the order they were declared.
1305 */
1306 static int bypass_pg_num(struct multipath *m, const char *pgstr, bool bypassed)
1307 {
1308 struct priority_group *pg;
1309 unsigned pgnum;
1310 char dummy;
1311
1312 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1313 !m->nr_priority_groups || (pgnum > m->nr_priority_groups)) {
1314 DMWARN("invalid PG number supplied to bypass_pg");
1315 return -EINVAL;
1316 }
1317
1318 list_for_each_entry(pg, &m->priority_groups, list) {
1319 if (!--pgnum)
1320 break;
1321 }
1322
1323 bypass_pg(m, pg, bypassed);
1324 return 0;
1325 }
1326
1327 /*
1328 * Should we retry pg_init immediately?
1329 */
1330 static bool pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath)
1331 {
1332 unsigned long flags;
1333 bool limit_reached = false;
1334
1335 spin_lock_irqsave(&m->lock, flags);
1336
1337 if (atomic_read(&m->pg_init_count) <= m->pg_init_retries &&
1338 !test_bit(MPATHF_PG_INIT_DISABLED, &m->flags))
1339 set_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
1340 else
1341 limit_reached = true;
1342
1343 spin_unlock_irqrestore(&m->lock, flags);
1344
1345 return limit_reached;
1346 }
1347
1348 static void pg_init_done(void *data, int errors)
1349 {
1350 struct pgpath *pgpath = data;
1351 struct priority_group *pg = pgpath->pg;
1352 struct multipath *m = pg->m;
1353 unsigned long flags;
1354 bool delay_retry = false;
1355
1356 /* device or driver problems */
1357 switch (errors) {
1358 case SCSI_DH_OK:
1359 break;
1360 case SCSI_DH_NOSYS:
1361 if (!m->hw_handler_name) {
1362 errors = 0;
1363 break;
1364 }
1365 DMERR("Could not failover the device: Handler scsi_dh_%s "
1366 "Error %d.", m->hw_handler_name, errors);
1367 /*
1368 * Fail path for now, so we do not ping pong
1369 */
1370 fail_path(pgpath);
1371 break;
1372 case SCSI_DH_DEV_TEMP_BUSY:
1373 /*
1374 * Probably doing something like FW upgrade on the
1375 * controller so try the other pg.
1376 */
1377 bypass_pg(m, pg, true);
1378 break;
1379 case SCSI_DH_RETRY:
1380 /* Wait before retrying. */
1381 delay_retry = 1;
1382 case SCSI_DH_IMM_RETRY:
1383 case SCSI_DH_RES_TEMP_UNAVAIL:
1384 if (pg_init_limit_reached(m, pgpath))
1385 fail_path(pgpath);
1386 errors = 0;
1387 break;
1388 case SCSI_DH_DEV_OFFLINED:
1389 default:
1390 /*
1391 * We probably do not want to fail the path for a device
1392 * error, but this is what the old dm did. In future
1393 * patches we can do more advanced handling.
1394 */
1395 fail_path(pgpath);
1396 }
1397
1398 spin_lock_irqsave(&m->lock, flags);
1399 if (errors) {
1400 if (pgpath == m->current_pgpath) {
1401 DMERR("Could not failover device. Error %d.", errors);
1402 m->current_pgpath = NULL;
1403 m->current_pg = NULL;
1404 }
1405 } else if (!test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
1406 pg->bypassed = false;
1407
1408 if (atomic_dec_return(&m->pg_init_in_progress) > 0)
1409 /* Activations of other paths are still on going */
1410 goto out;
1411
1412 if (test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags)) {
1413 if (delay_retry)
1414 set_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
1415 else
1416 clear_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
1417
1418 if (__pg_init_all_paths(m))
1419 goto out;
1420 }
1421 clear_bit(MPATHF_QUEUE_IO, &m->flags);
1422
1423 process_queued_io_list(m);
1424
1425 /*
1426 * Wake up any thread waiting to suspend.
1427 */
1428 wake_up(&m->pg_init_wait);
1429
1430 out:
1431 spin_unlock_irqrestore(&m->lock, flags);
1432 }
1433
1434 static void activate_or_offline_path(struct pgpath *pgpath)
1435 {
1436 struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
1437
1438 if (pgpath->is_active && !blk_queue_dying(q))
1439 scsi_dh_activate(q, pg_init_done, pgpath);
1440 else
1441 pg_init_done(pgpath, SCSI_DH_DEV_OFFLINED);
1442 }
1443
1444 static void activate_path_work(struct work_struct *work)
1445 {
1446 struct pgpath *pgpath =
1447 container_of(work, struct pgpath, activate_path.work);
1448
1449 activate_or_offline_path(pgpath);
1450 }
1451
1452 static int noretry_error(blk_status_t error)
1453 {
1454 switch (error) {
1455 case BLK_STS_NOTSUPP:
1456 case BLK_STS_NOSPC:
1457 case BLK_STS_TARGET:
1458 case BLK_STS_NEXUS:
1459 case BLK_STS_MEDIUM:
1460 return 1;
1461 }
1462
1463 /* Anything else could be a path failure, so should be retried */
1464 return 0;
1465 }
1466
1467 static int multipath_end_io(struct dm_target *ti, struct request *clone,
1468 blk_status_t error, union map_info *map_context)
1469 {
1470 struct dm_mpath_io *mpio = get_mpio(map_context);
1471 struct pgpath *pgpath = mpio->pgpath;
1472 int r = DM_ENDIO_DONE;
1473
1474 /*
1475 * We don't queue any clone request inside the multipath target
1476 * during end I/O handling, since those clone requests don't have
1477 * bio clones. If we queue them inside the multipath target,
1478 * we need to make bio clones, that requires memory allocation.
1479 * (See drivers/md/dm-rq.c:end_clone_bio() about why the clone requests
1480 * don't have bio clones.)
1481 * Instead of queueing the clone request here, we queue the original
1482 * request into dm core, which will remake a clone request and
1483 * clone bios for it and resubmit it later.
1484 */
1485 if (error && !noretry_error(error)) {
1486 struct multipath *m = ti->private;
1487
1488 r = DM_ENDIO_REQUEUE;
1489
1490 if (pgpath)
1491 fail_path(pgpath);
1492
1493 if (atomic_read(&m->nr_valid_paths) == 0 &&
1494 !test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
1495 if (error == BLK_STS_IOERR)
1496 dm_report_EIO(m);
1497 /* complete with the original error */
1498 r = DM_ENDIO_DONE;
1499 }
1500 }
1501
1502 if (pgpath) {
1503 struct path_selector *ps = &pgpath->pg->ps;
1504
1505 if (ps->type->end_io)
1506 ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
1507 }
1508
1509 return r;
1510 }
1511
1512 static int multipath_end_io_bio(struct dm_target *ti, struct bio *clone,
1513 blk_status_t *error)
1514 {
1515 struct multipath *m = ti->private;
1516 struct dm_mpath_io *mpio = get_mpio_from_bio(clone);
1517 struct pgpath *pgpath = mpio->pgpath;
1518 unsigned long flags;
1519 int r = DM_ENDIO_DONE;
1520
1521 if (!*error || noretry_error(*error))
1522 goto done;
1523
1524 if (pgpath)
1525 fail_path(pgpath);
1526
1527 if (atomic_read(&m->nr_valid_paths) == 0 &&
1528 !test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
1529 dm_report_EIO(m);
1530 *error = BLK_STS_IOERR;
1531 goto done;
1532 }
1533
1534 /* Queue for the daemon to resubmit */
1535 dm_bio_restore(get_bio_details_from_bio(clone), clone);
1536
1537 spin_lock_irqsave(&m->lock, flags);
1538 bio_list_add(&m->queued_bios, clone);
1539 spin_unlock_irqrestore(&m->lock, flags);
1540 if (!test_bit(MPATHF_QUEUE_IO, &m->flags))
1541 queue_work(kmultipathd, &m->process_queued_bios);
1542
1543 r = DM_ENDIO_INCOMPLETE;
1544 done:
1545 if (pgpath) {
1546 struct path_selector *ps = &pgpath->pg->ps;
1547
1548 if (ps->type->end_io)
1549 ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
1550 }
1551
1552 return r;
1553 }
1554
1555 /*
1556 * Suspend can't complete until all the I/O is processed so if
1557 * the last path fails we must error any remaining I/O.
1558 * Note that if the freeze_bdev fails while suspending, the
1559 * queue_if_no_path state is lost - userspace should reset it.
1560 */
1561 static void multipath_presuspend(struct dm_target *ti)
1562 {
1563 struct multipath *m = ti->private;
1564
1565 queue_if_no_path(m, false, true);
1566 }
1567
1568 static void multipath_postsuspend(struct dm_target *ti)
1569 {
1570 struct multipath *m = ti->private;
1571
1572 mutex_lock(&m->work_mutex);
1573 flush_multipath_work(m);
1574 mutex_unlock(&m->work_mutex);
1575 }
1576
1577 /*
1578 * Restore the queue_if_no_path setting.
1579 */
1580 static void multipath_resume(struct dm_target *ti)
1581 {
1582 struct multipath *m = ti->private;
1583 unsigned long flags;
1584
1585 spin_lock_irqsave(&m->lock, flags);
1586 assign_bit(test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags),
1587 MPATHF_QUEUE_IF_NO_PATH, &m->flags);
1588 spin_unlock_irqrestore(&m->lock, flags);
1589 }
1590
1591 /*
1592 * Info output has the following format:
1593 * num_multipath_feature_args [multipath_feature_args]*
1594 * num_handler_status_args [handler_status_args]*
1595 * num_groups init_group_number
1596 * [A|D|E num_ps_status_args [ps_status_args]*
1597 * num_paths num_selector_args
1598 * [path_dev A|F fail_count [selector_args]* ]+ ]+
1599 *
1600 * Table output has the following format (identical to the constructor string):
1601 * num_feature_args [features_args]*
1602 * num_handler_args hw_handler [hw_handler_args]*
1603 * num_groups init_group_number
1604 * [priority selector-name num_ps_args [ps_args]*
1605 * num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
1606 */
1607 static void multipath_status(struct dm_target *ti, status_type_t type,
1608 unsigned status_flags, char *result, unsigned maxlen)
1609 {
1610 int sz = 0;
1611 unsigned long flags;
1612 struct multipath *m = ti->private;
1613 struct priority_group *pg;
1614 struct pgpath *p;
1615 unsigned pg_num;
1616 char state;
1617
1618 spin_lock_irqsave(&m->lock, flags);
1619
1620 /* Features */
1621 if (type == STATUSTYPE_INFO)
1622 DMEMIT("2 %u %u ", test_bit(MPATHF_QUEUE_IO, &m->flags),
1623 atomic_read(&m->pg_init_count));
1624 else {
1625 DMEMIT("%u ", test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) +
1626 (m->pg_init_retries > 0) * 2 +
1627 (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT) * 2 +
1628 test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags) +
1629 (m->queue_mode != DM_TYPE_REQUEST_BASED) * 2);
1630
1631 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
1632 DMEMIT("queue_if_no_path ");
1633 if (m->pg_init_retries)
1634 DMEMIT("pg_init_retries %u ", m->pg_init_retries);
1635 if (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT)
1636 DMEMIT("pg_init_delay_msecs %u ", m->pg_init_delay_msecs);
1637 if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags))
1638 DMEMIT("retain_attached_hw_handler ");
1639 if (m->queue_mode != DM_TYPE_REQUEST_BASED) {
1640 switch(m->queue_mode) {
1641 case DM_TYPE_BIO_BASED:
1642 DMEMIT("queue_mode bio ");
1643 break;
1644 case DM_TYPE_MQ_REQUEST_BASED:
1645 DMEMIT("queue_mode mq ");
1646 break;
1647 default:
1648 WARN_ON_ONCE(true);
1649 break;
1650 }
1651 }
1652 }
1653
1654 if (!m->hw_handler_name || type == STATUSTYPE_INFO)
1655 DMEMIT("0 ");
1656 else
1657 DMEMIT("1 %s ", m->hw_handler_name);
1658
1659 DMEMIT("%u ", m->nr_priority_groups);
1660
1661 if (m->next_pg)
1662 pg_num = m->next_pg->pg_num;
1663 else if (m->current_pg)
1664 pg_num = m->current_pg->pg_num;
1665 else
1666 pg_num = (m->nr_priority_groups ? 1 : 0);
1667
1668 DMEMIT("%u ", pg_num);
1669
1670 switch (type) {
1671 case STATUSTYPE_INFO:
1672 list_for_each_entry(pg, &m->priority_groups, list) {
1673 if (pg->bypassed)
1674 state = 'D'; /* Disabled */
1675 else if (pg == m->current_pg)
1676 state = 'A'; /* Currently Active */
1677 else
1678 state = 'E'; /* Enabled */
1679
1680 DMEMIT("%c ", state);
1681
1682 if (pg->ps.type->status)
1683 sz += pg->ps.type->status(&pg->ps, NULL, type,
1684 result + sz,
1685 maxlen - sz);
1686 else
1687 DMEMIT("0 ");
1688
1689 DMEMIT("%u %u ", pg->nr_pgpaths,
1690 pg->ps.type->info_args);
1691
1692 list_for_each_entry(p, &pg->pgpaths, list) {
1693 DMEMIT("%s %s %u ", p->path.dev->name,
1694 p->is_active ? "A" : "F",
1695 p->fail_count);
1696 if (pg->ps.type->status)
1697 sz += pg->ps.type->status(&pg->ps,
1698 &p->path, type, result + sz,
1699 maxlen - sz);
1700 }
1701 }
1702 break;
1703
1704 case STATUSTYPE_TABLE:
1705 list_for_each_entry(pg, &m->priority_groups, list) {
1706 DMEMIT("%s ", pg->ps.type->name);
1707
1708 if (pg->ps.type->status)
1709 sz += pg->ps.type->status(&pg->ps, NULL, type,
1710 result + sz,
1711 maxlen - sz);
1712 else
1713 DMEMIT("0 ");
1714
1715 DMEMIT("%u %u ", pg->nr_pgpaths,
1716 pg->ps.type->table_args);
1717
1718 list_for_each_entry(p, &pg->pgpaths, list) {
1719 DMEMIT("%s ", p->path.dev->name);
1720 if (pg->ps.type->status)
1721 sz += pg->ps.type->status(&pg->ps,
1722 &p->path, type, result + sz,
1723 maxlen - sz);
1724 }
1725 }
1726 break;
1727 }
1728
1729 spin_unlock_irqrestore(&m->lock, flags);
1730 }
1731
1732 static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
1733 {
1734 int r = -EINVAL;
1735 struct dm_dev *dev;
1736 struct multipath *m = ti->private;
1737 action_fn action;
1738
1739 mutex_lock(&m->work_mutex);
1740
1741 if (dm_suspended(ti)) {
1742 r = -EBUSY;
1743 goto out;
1744 }
1745
1746 if (argc == 1) {
1747 if (!strcasecmp(argv[0], "queue_if_no_path")) {
1748 r = queue_if_no_path(m, true, false);
1749 goto out;
1750 } else if (!strcasecmp(argv[0], "fail_if_no_path")) {
1751 r = queue_if_no_path(m, false, false);
1752 goto out;
1753 }
1754 }
1755
1756 if (argc != 2) {
1757 DMWARN("Invalid multipath message arguments. Expected 2 arguments, got %d.", argc);
1758 goto out;
1759 }
1760
1761 if (!strcasecmp(argv[0], "disable_group")) {
1762 r = bypass_pg_num(m, argv[1], true);
1763 goto out;
1764 } else if (!strcasecmp(argv[0], "enable_group")) {
1765 r = bypass_pg_num(m, argv[1], false);
1766 goto out;
1767 } else if (!strcasecmp(argv[0], "switch_group")) {
1768 r = switch_pg_num(m, argv[1]);
1769 goto out;
1770 } else if (!strcasecmp(argv[0], "reinstate_path"))
1771 action = reinstate_path;
1772 else if (!strcasecmp(argv[0], "fail_path"))
1773 action = fail_path;
1774 else {
1775 DMWARN("Unrecognised multipath message received: %s", argv[0]);
1776 goto out;
1777 }
1778
1779 r = dm_get_device(ti, argv[1], dm_table_get_mode(ti->table), &dev);
1780 if (r) {
1781 DMWARN("message: error getting device %s",
1782 argv[1]);
1783 goto out;
1784 }
1785
1786 r = action_dev(m, dev, action);
1787
1788 dm_put_device(ti, dev);
1789
1790 out:
1791 mutex_unlock(&m->work_mutex);
1792 return r;
1793 }
1794
1795 static int multipath_prepare_ioctl(struct dm_target *ti,
1796 struct block_device **bdev, fmode_t *mode)
1797 {
1798 struct multipath *m = ti->private;
1799 struct pgpath *current_pgpath;
1800 int r;
1801
1802 current_pgpath = lockless_dereference(m->current_pgpath);
1803 if (!current_pgpath)
1804 current_pgpath = choose_pgpath(m, 0);
1805
1806 if (current_pgpath) {
1807 if (!test_bit(MPATHF_QUEUE_IO, &m->flags)) {
1808 *bdev = current_pgpath->path.dev->bdev;
1809 *mode = current_pgpath->path.dev->mode;
1810 r = 0;
1811 } else {
1812 /* pg_init has not started or completed */
1813 r = -ENOTCONN;
1814 }
1815 } else {
1816 /* No path is available */
1817 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
1818 r = -ENOTCONN;
1819 else
1820 r = -EIO;
1821 }
1822
1823 if (r == -ENOTCONN) {
1824 if (!lockless_dereference(m->current_pg)) {
1825 /* Path status changed, redo selection */
1826 (void) choose_pgpath(m, 0);
1827 }
1828 if (test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
1829 pg_init_all_paths(m);
1830 dm_table_run_md_queue_async(m->ti->table);
1831 process_queued_io_list(m);
1832 }
1833
1834 /*
1835 * Only pass ioctls through if the device sizes match exactly.
1836 */
1837 if (!r && ti->len != i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT)
1838 return 1;
1839 return r;
1840 }
1841
1842 static int multipath_iterate_devices(struct dm_target *ti,
1843 iterate_devices_callout_fn fn, void *data)
1844 {
1845 struct multipath *m = ti->private;
1846 struct priority_group *pg;
1847 struct pgpath *p;
1848 int ret = 0;
1849
1850 list_for_each_entry(pg, &m->priority_groups, list) {
1851 list_for_each_entry(p, &pg->pgpaths, list) {
1852 ret = fn(ti, p->path.dev, ti->begin, ti->len, data);
1853 if (ret)
1854 goto out;
1855 }
1856 }
1857
1858 out:
1859 return ret;
1860 }
1861
1862 static int pgpath_busy(struct pgpath *pgpath)
1863 {
1864 struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
1865
1866 return blk_lld_busy(q);
1867 }
1868
1869 /*
1870 * We return "busy", only when we can map I/Os but underlying devices
1871 * are busy (so even if we map I/Os now, the I/Os will wait on
1872 * the underlying queue).
1873 * In other words, if we want to kill I/Os or queue them inside us
1874 * due to map unavailability, we don't return "busy". Otherwise,
1875 * dm core won't give us the I/Os and we can't do what we want.
1876 */
1877 static int multipath_busy(struct dm_target *ti)
1878 {
1879 bool busy = false, has_active = false;
1880 struct multipath *m = ti->private;
1881 struct priority_group *pg, *next_pg;
1882 struct pgpath *pgpath;
1883
1884 /* pg_init in progress */
1885 if (atomic_read(&m->pg_init_in_progress))
1886 return true;
1887
1888 /* no paths available, for blk-mq: rely on IO mapping to delay requeue */
1889 if (!atomic_read(&m->nr_valid_paths) && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
1890 return (m->queue_mode != DM_TYPE_MQ_REQUEST_BASED);
1891
1892 /* Guess which priority_group will be used at next mapping time */
1893 pg = lockless_dereference(m->current_pg);
1894 next_pg = lockless_dereference(m->next_pg);
1895 if (unlikely(!lockless_dereference(m->current_pgpath) && next_pg))
1896 pg = next_pg;
1897
1898 if (!pg) {
1899 /*
1900 * We don't know which pg will be used at next mapping time.
1901 * We don't call choose_pgpath() here to avoid to trigger
1902 * pg_init just by busy checking.
1903 * So we don't know whether underlying devices we will be using
1904 * at next mapping time are busy or not. Just try mapping.
1905 */
1906 return busy;
1907 }
1908
1909 /*
1910 * If there is one non-busy active path at least, the path selector
1911 * will be able to select it. So we consider such a pg as not busy.
1912 */
1913 busy = true;
1914 list_for_each_entry(pgpath, &pg->pgpaths, list) {
1915 if (pgpath->is_active) {
1916 has_active = true;
1917 if (!pgpath_busy(pgpath)) {
1918 busy = false;
1919 break;
1920 }
1921 }
1922 }
1923
1924 if (!has_active) {
1925 /*
1926 * No active path in this pg, so this pg won't be used and
1927 * the current_pg will be changed at next mapping time.
1928 * We need to try mapping to determine it.
1929 */
1930 busy = false;
1931 }
1932
1933 return busy;
1934 }
1935
1936 /*-----------------------------------------------------------------
1937 * Module setup
1938 *---------------------------------------------------------------*/
1939 static struct target_type multipath_target = {
1940 .name = "multipath",
1941 .version = {1, 12, 0},
1942 .features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE,
1943 .module = THIS_MODULE,
1944 .ctr = multipath_ctr,
1945 .dtr = multipath_dtr,
1946 .clone_and_map_rq = multipath_clone_and_map,
1947 .release_clone_rq = multipath_release_clone,
1948 .rq_end_io = multipath_end_io,
1949 .map = multipath_map_bio,
1950 .end_io = multipath_end_io_bio,
1951 .presuspend = multipath_presuspend,
1952 .postsuspend = multipath_postsuspend,
1953 .resume = multipath_resume,
1954 .status = multipath_status,
1955 .message = multipath_message,
1956 .prepare_ioctl = multipath_prepare_ioctl,
1957 .iterate_devices = multipath_iterate_devices,
1958 .busy = multipath_busy,
1959 };
1960
1961 static int __init dm_multipath_init(void)
1962 {
1963 int r;
1964
1965 r = dm_register_target(&multipath_target);
1966 if (r < 0) {
1967 DMERR("request-based register failed %d", r);
1968 r = -EINVAL;
1969 goto bad_register_target;
1970 }
1971
1972 kmultipathd = alloc_workqueue("kmpathd", WQ_MEM_RECLAIM, 0);
1973 if (!kmultipathd) {
1974 DMERR("failed to create workqueue kmpathd");
1975 r = -ENOMEM;
1976 goto bad_alloc_kmultipathd;
1977 }
1978
1979 /*
1980 * A separate workqueue is used to handle the device handlers
1981 * to avoid overloading existing workqueue. Overloading the
1982 * old workqueue would also create a bottleneck in the
1983 * path of the storage hardware device activation.
1984 */
1985 kmpath_handlerd = alloc_ordered_workqueue("kmpath_handlerd",
1986 WQ_MEM_RECLAIM);
1987 if (!kmpath_handlerd) {
1988 DMERR("failed to create workqueue kmpath_handlerd");
1989 r = -ENOMEM;
1990 goto bad_alloc_kmpath_handlerd;
1991 }
1992
1993 return 0;
1994
1995 bad_alloc_kmpath_handlerd:
1996 destroy_workqueue(kmultipathd);
1997 bad_alloc_kmultipathd:
1998 dm_unregister_target(&multipath_target);
1999 bad_register_target:
2000 return r;
2001 }
2002
2003 static void __exit dm_multipath_exit(void)
2004 {
2005 destroy_workqueue(kmpath_handlerd);
2006 destroy_workqueue(kmultipathd);
2007
2008 dm_unregister_target(&multipath_target);
2009 }
2010
2011 module_init(dm_multipath_init);
2012 module_exit(dm_multipath_exit);
2013
2014 MODULE_DESCRIPTION(DM_NAME " multipath target");
2015 MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
2016 MODULE_LICENSE("GPL");