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1/*
2 * Copyright (C) 2003 Sistina Software Limited.
3 * Copyright (C) 2004-2005 Red Hat, Inc. All rights reserved.
4 *
5 * This file is released under the GPL.
6 */
7
8#include <linux/device-mapper.h>
9
10#include "dm.h"
11#include "dm-path-selector.h"
12#include "dm-uevent.h"
13
14#include <linux/blkdev.h>
15#include <linux/ctype.h>
16#include <linux/init.h>
17#include <linux/mempool.h>
18#include <linux/module.h>
19#include <linux/pagemap.h>
20#include <linux/slab.h>
21#include <linux/time.h>
22#include <linux/workqueue.h>
23#include <linux/delay.h>
24#include <scsi/scsi_dh.h>
25#include <linux/atomic.h>
26#include <linux/blk-mq.h>
27
28#define DM_MSG_PREFIX "multipath"
29#define DM_PG_INIT_DELAY_MSECS 2000
30#define DM_PG_INIT_DELAY_DEFAULT ((unsigned) -1)
31
32/* Path properties */
33struct pgpath {
34 struct list_head list;
35
36 struct priority_group *pg; /* Owning PG */
37 unsigned fail_count; /* Cumulative failure count */
38
39 struct dm_path path;
40 struct delayed_work activate_path;
41
42 bool is_active:1; /* Path status */
43};
44
45#define path_to_pgpath(__pgp) container_of((__pgp), struct pgpath, path)
46
47/*
48 * Paths are grouped into Priority Groups and numbered from 1 upwards.
49 * Each has a path selector which controls which path gets used.
50 */
51struct priority_group {
52 struct list_head list;
53
54 struct multipath *m; /* Owning multipath instance */
55 struct path_selector ps;
56
57 unsigned pg_num; /* Reference number */
58 unsigned nr_pgpaths; /* Number of paths in PG */
59 struct list_head pgpaths;
60
61 bool bypassed:1; /* Temporarily bypass this PG? */
62};
63
64/* Multipath context */
65struct multipath {
66 struct list_head list;
67 struct dm_target *ti;
68
69 const char *hw_handler_name;
70 char *hw_handler_params;
71
72 spinlock_t lock;
73
74 unsigned nr_priority_groups;
75 struct list_head priority_groups;
76
77 wait_queue_head_t pg_init_wait; /* Wait for pg_init completion */
78
79 unsigned pg_init_in_progress; /* Only one pg_init allowed at once */
80
81 unsigned nr_valid_paths; /* Total number of usable paths */
82 struct pgpath *current_pgpath;
83 struct priority_group *current_pg;
84 struct priority_group *next_pg; /* Switch to this PG if set */
85
86 bool queue_io:1; /* Must we queue all I/O? */
87 bool queue_if_no_path:1; /* Queue I/O if last path fails? */
88 bool saved_queue_if_no_path:1; /* Saved state during suspension */
89 bool retain_attached_hw_handler:1; /* If there's already a hw_handler present, don't change it. */
90 bool pg_init_disabled:1; /* pg_init is not currently allowed */
91 bool pg_init_required:1; /* pg_init needs calling? */
92 bool pg_init_delay_retry:1; /* Delay pg_init retry? */
93
94 unsigned pg_init_retries; /* Number of times to retry pg_init */
95 unsigned pg_init_count; /* Number of times pg_init called */
96 unsigned pg_init_delay_msecs; /* Number of msecs before pg_init retry */
97
98 struct work_struct trigger_event;
99
100 /*
101 * We must use a mempool of dm_mpath_io structs so that we
102 * can resubmit bios on error.
103 */
104 mempool_t *mpio_pool;
105
106 struct mutex work_mutex;
107};
108
109/*
110 * Context information attached to each bio we process.
111 */
112struct dm_mpath_io {
113 struct pgpath *pgpath;
114 size_t nr_bytes;
115};
116
117typedef int (*action_fn) (struct pgpath *pgpath);
118
119static struct kmem_cache *_mpio_cache;
120
121static struct workqueue_struct *kmultipathd, *kmpath_handlerd;
122static void trigger_event(struct work_struct *work);
123static void activate_path(struct work_struct *work);
124
125
126/*-----------------------------------------------
127 * Allocation routines
128 *-----------------------------------------------*/
129
130static struct pgpath *alloc_pgpath(void)
131{
132 struct pgpath *pgpath = kzalloc(sizeof(*pgpath), GFP_KERNEL);
133
134 if (pgpath) {
135 pgpath->is_active = true;
136 INIT_DELAYED_WORK(&pgpath->activate_path, activate_path);
137 }
138
139 return pgpath;
140}
141
142static void free_pgpath(struct pgpath *pgpath)
143{
144 kfree(pgpath);
145}
146
147static struct priority_group *alloc_priority_group(void)
148{
149 struct priority_group *pg;
150
151 pg = kzalloc(sizeof(*pg), GFP_KERNEL);
152
153 if (pg)
154 INIT_LIST_HEAD(&pg->pgpaths);
155
156 return pg;
157}
158
159static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti)
160{
161 struct pgpath *pgpath, *tmp;
162
163 list_for_each_entry_safe(pgpath, tmp, pgpaths, list) {
164 list_del(&pgpath->list);
165 dm_put_device(ti, pgpath->path.dev);
166 free_pgpath(pgpath);
167 }
168}
169
170static void free_priority_group(struct priority_group *pg,
171 struct dm_target *ti)
172{
173 struct path_selector *ps = &pg->ps;
174
175 if (ps->type) {
176 ps->type->destroy(ps);
177 dm_put_path_selector(ps->type);
178 }
179
180 free_pgpaths(&pg->pgpaths, ti);
181 kfree(pg);
182}
183
184static struct multipath *alloc_multipath(struct dm_target *ti, bool use_blk_mq)
185{
186 struct multipath *m;
187
188 m = kzalloc(sizeof(*m), GFP_KERNEL);
189 if (m) {
190 INIT_LIST_HEAD(&m->priority_groups);
191 spin_lock_init(&m->lock);
192 m->queue_io = true;
193 m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT;
194 INIT_WORK(&m->trigger_event, trigger_event);
195 init_waitqueue_head(&m->pg_init_wait);
196 mutex_init(&m->work_mutex);
197
198 m->mpio_pool = NULL;
199 if (!use_blk_mq) {
200 unsigned min_ios = dm_get_reserved_rq_based_ios();
201
202 m->mpio_pool = mempool_create_slab_pool(min_ios, _mpio_cache);
203 if (!m->mpio_pool) {
204 kfree(m);
205 return NULL;
206 }
207 }
208
209 m->ti = ti;
210 ti->private = m;
211 }
212
213 return m;
214}
215
216static void free_multipath(struct multipath *m)
217{
218 struct priority_group *pg, *tmp;
219
220 list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) {
221 list_del(&pg->list);
222 free_priority_group(pg, m->ti);
223 }
224
225 kfree(m->hw_handler_name);
226 kfree(m->hw_handler_params);
227 mempool_destroy(m->mpio_pool);
228 kfree(m);
229}
230
231static struct dm_mpath_io *get_mpio(union map_info *info)
232{
233 return info->ptr;
234}
235
236static struct dm_mpath_io *set_mpio(struct multipath *m, union map_info *info)
237{
238 struct dm_mpath_io *mpio;
239
240 if (!m->mpio_pool) {
241 /* Use blk-mq pdu memory requested via per_io_data_size */
242 mpio = get_mpio(info);
243 memset(mpio, 0, sizeof(*mpio));
244 return mpio;
245 }
246
247 mpio = mempool_alloc(m->mpio_pool, GFP_ATOMIC);
248 if (!mpio)
249 return NULL;
250
251 memset(mpio, 0, sizeof(*mpio));
252 info->ptr = mpio;
253
254 return mpio;
255}
256
257static void clear_request_fn_mpio(struct multipath *m, union map_info *info)
258{
259 /* Only needed for non blk-mq (.request_fn) multipath */
260 if (m->mpio_pool) {
261 struct dm_mpath_io *mpio = info->ptr;
262
263 info->ptr = NULL;
264 mempool_free(mpio, m->mpio_pool);
265 }
266}
267
268/*-----------------------------------------------
269 * Path selection
270 *-----------------------------------------------*/
271
272static int __pg_init_all_paths(struct multipath *m)
273{
274 struct pgpath *pgpath;
275 unsigned long pg_init_delay = 0;
276
277 if (m->pg_init_in_progress || m->pg_init_disabled)
278 return 0;
279
280 m->pg_init_count++;
281 m->pg_init_required = false;
282
283 /* Check here to reset pg_init_required */
284 if (!m->current_pg)
285 return 0;
286
287 if (m->pg_init_delay_retry)
288 pg_init_delay = msecs_to_jiffies(m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT ?
289 m->pg_init_delay_msecs : DM_PG_INIT_DELAY_MSECS);
290 list_for_each_entry(pgpath, &m->current_pg->pgpaths, list) {
291 /* Skip failed paths */
292 if (!pgpath->is_active)
293 continue;
294 if (queue_delayed_work(kmpath_handlerd, &pgpath->activate_path,
295 pg_init_delay))
296 m->pg_init_in_progress++;
297 }
298 return m->pg_init_in_progress;
299}
300
301static void __switch_pg(struct multipath *m, struct pgpath *pgpath)
302{
303 m->current_pg = pgpath->pg;
304
305 /* Must we initialise the PG first, and queue I/O till it's ready? */
306 if (m->hw_handler_name) {
307 m->pg_init_required = true;
308 m->queue_io = true;
309 } else {
310 m->pg_init_required = false;
311 m->queue_io = false;
312 }
313
314 m->pg_init_count = 0;
315}
316
317static int __choose_path_in_pg(struct multipath *m, struct priority_group *pg,
318 size_t nr_bytes)
319{
320 struct dm_path *path;
321
322 path = pg->ps.type->select_path(&pg->ps, nr_bytes);
323 if (!path)
324 return -ENXIO;
325
326 m->current_pgpath = path_to_pgpath(path);
327
328 if (m->current_pg != pg)
329 __switch_pg(m, m->current_pgpath);
330
331 return 0;
332}
333
334static void __choose_pgpath(struct multipath *m, size_t nr_bytes)
335{
336 struct priority_group *pg;
337 bool bypassed = true;
338
339 if (!m->nr_valid_paths) {
340 m->queue_io = false;
341 goto failed;
342 }
343
344 /* Were we instructed to switch PG? */
345 if (m->next_pg) {
346 pg = m->next_pg;
347 m->next_pg = NULL;
348 if (!__choose_path_in_pg(m, pg, nr_bytes))
349 return;
350 }
351
352 /* Don't change PG until it has no remaining paths */
353 if (m->current_pg && !__choose_path_in_pg(m, m->current_pg, nr_bytes))
354 return;
355
356 /*
357 * Loop through priority groups until we find a valid path.
358 * First time we skip PGs marked 'bypassed'.
359 * Second time we only try the ones we skipped, but set
360 * pg_init_delay_retry so we do not hammer controllers.
361 */
362 do {
363 list_for_each_entry(pg, &m->priority_groups, list) {
364 if (pg->bypassed == bypassed)
365 continue;
366 if (!__choose_path_in_pg(m, pg, nr_bytes)) {
367 if (!bypassed)
368 m->pg_init_delay_retry = true;
369 return;
370 }
371 }
372 } while (bypassed--);
373
374failed:
375 m->current_pgpath = NULL;
376 m->current_pg = NULL;
377}
378
379/*
380 * Check whether bios must be queued in the device-mapper core rather
381 * than here in the target.
382 *
383 * m->lock must be held on entry.
384 *
385 * If m->queue_if_no_path and m->saved_queue_if_no_path hold the
386 * same value then we are not between multipath_presuspend()
387 * and multipath_resume() calls and we have no need to check
388 * for the DMF_NOFLUSH_SUSPENDING flag.
389 */
390static int __must_push_back(struct multipath *m)
391{
392 return (m->queue_if_no_path ||
393 (m->queue_if_no_path != m->saved_queue_if_no_path &&
394 dm_noflush_suspending(m->ti)));
395}
396
397/*
398 * Map cloned requests
399 */
400static int __multipath_map(struct dm_target *ti, struct request *clone,
401 union map_info *map_context,
402 struct request *rq, struct request **__clone)
403{
404 struct multipath *m = ti->private;
405 int r = DM_MAPIO_REQUEUE;
406 size_t nr_bytes = clone ? blk_rq_bytes(clone) : blk_rq_bytes(rq);
407 struct pgpath *pgpath;
408 struct block_device *bdev;
409 struct dm_mpath_io *mpio;
410
411 spin_lock_irq(&m->lock);
412
413 /* Do we need to select a new pgpath? */
414 if (!m->current_pgpath || !m->queue_io)
415 __choose_pgpath(m, nr_bytes);
416
417 pgpath = m->current_pgpath;
418
419 if (!pgpath) {
420 if (!__must_push_back(m))
421 r = -EIO; /* Failed */
422 goto out_unlock;
423 } else if (m->queue_io || m->pg_init_required) {
424 __pg_init_all_paths(m);
425 goto out_unlock;
426 }
427
428 mpio = set_mpio(m, map_context);
429 if (!mpio)
430 /* ENOMEM, requeue */
431 goto out_unlock;
432
433 mpio->pgpath = pgpath;
434 mpio->nr_bytes = nr_bytes;
435
436 bdev = pgpath->path.dev->bdev;
437
438 spin_unlock_irq(&m->lock);
439
440 if (clone) {
441 /*
442 * Old request-based interface: allocated clone is passed in.
443 * Used by: .request_fn stacked on .request_fn path(s).
444 */
445 clone->q = bdev_get_queue(bdev);
446 clone->rq_disk = bdev->bd_disk;
447 clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
448 } else {
449 /*
450 * blk-mq request-based interface; used by both:
451 * .request_fn stacked on blk-mq path(s) and
452 * blk-mq stacked on blk-mq path(s).
453 */
454 *__clone = blk_mq_alloc_request(bdev_get_queue(bdev),
455 rq_data_dir(rq), BLK_MQ_REQ_NOWAIT);
456 if (IS_ERR(*__clone)) {
457 /* ENOMEM, requeue */
458 clear_request_fn_mpio(m, map_context);
459 return r;
460 }
461 (*__clone)->bio = (*__clone)->biotail = NULL;
462 (*__clone)->rq_disk = bdev->bd_disk;
463 (*__clone)->cmd_flags |= REQ_FAILFAST_TRANSPORT;
464 }
465
466 if (pgpath->pg->ps.type->start_io)
467 pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
468 &pgpath->path,
469 nr_bytes);
470 return DM_MAPIO_REMAPPED;
471
472out_unlock:
473 spin_unlock_irq(&m->lock);
474
475 return r;
476}
477
478static int multipath_map(struct dm_target *ti, struct request *clone,
479 union map_info *map_context)
480{
481 return __multipath_map(ti, clone, map_context, NULL, NULL);
482}
483
484static int multipath_clone_and_map(struct dm_target *ti, struct request *rq,
485 union map_info *map_context,
486 struct request **clone)
487{
488 return __multipath_map(ti, NULL, map_context, rq, clone);
489}
490
491static void multipath_release_clone(struct request *clone)
492{
493 blk_mq_free_request(clone);
494}
495
496/*
497 * If we run out of usable paths, should we queue I/O or error it?
498 */
499static int queue_if_no_path(struct multipath *m, bool queue_if_no_path,
500 bool save_old_value)
501{
502 unsigned long flags;
503
504 spin_lock_irqsave(&m->lock, flags);
505
506 if (save_old_value)
507 m->saved_queue_if_no_path = m->queue_if_no_path;
508 else
509 m->saved_queue_if_no_path = queue_if_no_path;
510 m->queue_if_no_path = queue_if_no_path;
511 spin_unlock_irqrestore(&m->lock, flags);
512
513 if (!queue_if_no_path)
514 dm_table_run_md_queue_async(m->ti->table);
515
516 return 0;
517}
518
519/*
520 * An event is triggered whenever a path is taken out of use.
521 * Includes path failure and PG bypass.
522 */
523static void trigger_event(struct work_struct *work)
524{
525 struct multipath *m =
526 container_of(work, struct multipath, trigger_event);
527
528 dm_table_event(m->ti->table);
529}
530
531/*-----------------------------------------------------------------
532 * Constructor/argument parsing:
533 * <#multipath feature args> [<arg>]*
534 * <#hw_handler args> [hw_handler [<arg>]*]
535 * <#priority groups>
536 * <initial priority group>
537 * [<selector> <#selector args> [<arg>]*
538 * <#paths> <#per-path selector args>
539 * [<path> [<arg>]* ]+ ]+
540 *---------------------------------------------------------------*/
541static int parse_path_selector(struct dm_arg_set *as, struct priority_group *pg,
542 struct dm_target *ti)
543{
544 int r;
545 struct path_selector_type *pst;
546 unsigned ps_argc;
547
548 static struct dm_arg _args[] = {
549 {0, 1024, "invalid number of path selector args"},
550 };
551
552 pst = dm_get_path_selector(dm_shift_arg(as));
553 if (!pst) {
554 ti->error = "unknown path selector type";
555 return -EINVAL;
556 }
557
558 r = dm_read_arg_group(_args, as, &ps_argc, &ti->error);
559 if (r) {
560 dm_put_path_selector(pst);
561 return -EINVAL;
562 }
563
564 r = pst->create(&pg->ps, ps_argc, as->argv);
565 if (r) {
566 dm_put_path_selector(pst);
567 ti->error = "path selector constructor failed";
568 return r;
569 }
570
571 pg->ps.type = pst;
572 dm_consume_args(as, ps_argc);
573
574 return 0;
575}
576
577static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps,
578 struct dm_target *ti)
579{
580 int r;
581 struct pgpath *p;
582 struct multipath *m = ti->private;
583 struct request_queue *q = NULL;
584 const char *attached_handler_name;
585
586 /* we need at least a path arg */
587 if (as->argc < 1) {
588 ti->error = "no device given";
589 return ERR_PTR(-EINVAL);
590 }
591
592 p = alloc_pgpath();
593 if (!p)
594 return ERR_PTR(-ENOMEM);
595
596 r = dm_get_device(ti, dm_shift_arg(as), dm_table_get_mode(ti->table),
597 &p->path.dev);
598 if (r) {
599 ti->error = "error getting device";
600 goto bad;
601 }
602
603 if (m->retain_attached_hw_handler || m->hw_handler_name)
604 q = bdev_get_queue(p->path.dev->bdev);
605
606 if (m->retain_attached_hw_handler) {
607retain:
608 attached_handler_name = scsi_dh_attached_handler_name(q, GFP_KERNEL);
609 if (attached_handler_name) {
610 /*
611 * Reset hw_handler_name to match the attached handler
612 * and clear any hw_handler_params associated with the
613 * ignored handler.
614 *
615 * NB. This modifies the table line to show the actual
616 * handler instead of the original table passed in.
617 */
618 kfree(m->hw_handler_name);
619 m->hw_handler_name = attached_handler_name;
620
621 kfree(m->hw_handler_params);
622 m->hw_handler_params = NULL;
623 }
624 }
625
626 if (m->hw_handler_name) {
627 r = scsi_dh_attach(q, m->hw_handler_name);
628 if (r == -EBUSY) {
629 char b[BDEVNAME_SIZE];
630
631 printk(KERN_INFO "dm-mpath: retaining handler on device %s\n",
632 bdevname(p->path.dev->bdev, b));
633 goto retain;
634 }
635 if (r < 0) {
636 ti->error = "error attaching hardware handler";
637 dm_put_device(ti, p->path.dev);
638 goto bad;
639 }
640
641 if (m->hw_handler_params) {
642 r = scsi_dh_set_params(q, m->hw_handler_params);
643 if (r < 0) {
644 ti->error = "unable to set hardware "
645 "handler parameters";
646 dm_put_device(ti, p->path.dev);
647 goto bad;
648 }
649 }
650 }
651
652 r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
653 if (r) {
654 dm_put_device(ti, p->path.dev);
655 goto bad;
656 }
657
658 return p;
659
660 bad:
661 free_pgpath(p);
662 return ERR_PTR(r);
663}
664
665static struct priority_group *parse_priority_group(struct dm_arg_set *as,
666 struct multipath *m)
667{
668 static struct dm_arg _args[] = {
669 {1, 1024, "invalid number of paths"},
670 {0, 1024, "invalid number of selector args"}
671 };
672
673 int r;
674 unsigned i, nr_selector_args, nr_args;
675 struct priority_group *pg;
676 struct dm_target *ti = m->ti;
677
678 if (as->argc < 2) {
679 as->argc = 0;
680 ti->error = "not enough priority group arguments";
681 return ERR_PTR(-EINVAL);
682 }
683
684 pg = alloc_priority_group();
685 if (!pg) {
686 ti->error = "couldn't allocate priority group";
687 return ERR_PTR(-ENOMEM);
688 }
689 pg->m = m;
690
691 r = parse_path_selector(as, pg, ti);
692 if (r)
693 goto bad;
694
695 /*
696 * read the paths
697 */
698 r = dm_read_arg(_args, as, &pg->nr_pgpaths, &ti->error);
699 if (r)
700 goto bad;
701
702 r = dm_read_arg(_args + 1, as, &nr_selector_args, &ti->error);
703 if (r)
704 goto bad;
705
706 nr_args = 1 + nr_selector_args;
707 for (i = 0; i < pg->nr_pgpaths; i++) {
708 struct pgpath *pgpath;
709 struct dm_arg_set path_args;
710
711 if (as->argc < nr_args) {
712 ti->error = "not enough path parameters";
713 r = -EINVAL;
714 goto bad;
715 }
716
717 path_args.argc = nr_args;
718 path_args.argv = as->argv;
719
720 pgpath = parse_path(&path_args, &pg->ps, ti);
721 if (IS_ERR(pgpath)) {
722 r = PTR_ERR(pgpath);
723 goto bad;
724 }
725
726 pgpath->pg = pg;
727 list_add_tail(&pgpath->list, &pg->pgpaths);
728 dm_consume_args(as, nr_args);
729 }
730
731 return pg;
732
733 bad:
734 free_priority_group(pg, ti);
735 return ERR_PTR(r);
736}
737
738static int parse_hw_handler(struct dm_arg_set *as, struct multipath *m)
739{
740 unsigned hw_argc;
741 int ret;
742 struct dm_target *ti = m->ti;
743
744 static struct dm_arg _args[] = {
745 {0, 1024, "invalid number of hardware handler args"},
746 };
747
748 if (dm_read_arg_group(_args, as, &hw_argc, &ti->error))
749 return -EINVAL;
750
751 if (!hw_argc)
752 return 0;
753
754 m->hw_handler_name = kstrdup(dm_shift_arg(as), GFP_KERNEL);
755
756 if (hw_argc > 1) {
757 char *p;
758 int i, j, len = 4;
759
760 for (i = 0; i <= hw_argc - 2; i++)
761 len += strlen(as->argv[i]) + 1;
762 p = m->hw_handler_params = kzalloc(len, GFP_KERNEL);
763 if (!p) {
764 ti->error = "memory allocation failed";
765 ret = -ENOMEM;
766 goto fail;
767 }
768 j = sprintf(p, "%d", hw_argc - 1);
769 for (i = 0, p+=j+1; i <= hw_argc - 2; i++, p+=j+1)
770 j = sprintf(p, "%s", as->argv[i]);
771 }
772 dm_consume_args(as, hw_argc - 1);
773
774 return 0;
775fail:
776 kfree(m->hw_handler_name);
777 m->hw_handler_name = NULL;
778 return ret;
779}
780
781static int parse_features(struct dm_arg_set *as, struct multipath *m)
782{
783 int r;
784 unsigned argc;
785 struct dm_target *ti = m->ti;
786 const char *arg_name;
787
788 static struct dm_arg _args[] = {
789 {0, 6, "invalid number of feature args"},
790 {1, 50, "pg_init_retries must be between 1 and 50"},
791 {0, 60000, "pg_init_delay_msecs must be between 0 and 60000"},
792 };
793
794 r = dm_read_arg_group(_args, as, &argc, &ti->error);
795 if (r)
796 return -EINVAL;
797
798 if (!argc)
799 return 0;
800
801 do {
802 arg_name = dm_shift_arg(as);
803 argc--;
804
805 if (!strcasecmp(arg_name, "queue_if_no_path")) {
806 r = queue_if_no_path(m, true, false);
807 continue;
808 }
809
810 if (!strcasecmp(arg_name, "retain_attached_hw_handler")) {
811 m->retain_attached_hw_handler = true;
812 continue;
813 }
814
815 if (!strcasecmp(arg_name, "pg_init_retries") &&
816 (argc >= 1)) {
817 r = dm_read_arg(_args + 1, as, &m->pg_init_retries, &ti->error);
818 argc--;
819 continue;
820 }
821
822 if (!strcasecmp(arg_name, "pg_init_delay_msecs") &&
823 (argc >= 1)) {
824 r = dm_read_arg(_args + 2, as, &m->pg_init_delay_msecs, &ti->error);
825 argc--;
826 continue;
827 }
828
829 ti->error = "Unrecognised multipath feature request";
830 r = -EINVAL;
831 } while (argc && !r);
832
833 return r;
834}
835
836static int multipath_ctr(struct dm_target *ti, unsigned int argc,
837 char **argv)
838{
839 /* target arguments */
840 static struct dm_arg _args[] = {
841 {0, 1024, "invalid number of priority groups"},
842 {0, 1024, "invalid initial priority group number"},
843 };
844
845 int r;
846 struct multipath *m;
847 struct dm_arg_set as;
848 unsigned pg_count = 0;
849 unsigned next_pg_num;
850 bool use_blk_mq = dm_use_blk_mq(dm_table_get_md(ti->table));
851
852 as.argc = argc;
853 as.argv = argv;
854
855 m = alloc_multipath(ti, use_blk_mq);
856 if (!m) {
857 ti->error = "can't allocate multipath";
858 return -EINVAL;
859 }
860
861 r = parse_features(&as, m);
862 if (r)
863 goto bad;
864
865 r = parse_hw_handler(&as, m);
866 if (r)
867 goto bad;
868
869 r = dm_read_arg(_args, &as, &m->nr_priority_groups, &ti->error);
870 if (r)
871 goto bad;
872
873 r = dm_read_arg(_args + 1, &as, &next_pg_num, &ti->error);
874 if (r)
875 goto bad;
876
877 if ((!m->nr_priority_groups && next_pg_num) ||
878 (m->nr_priority_groups && !next_pg_num)) {
879 ti->error = "invalid initial priority group";
880 r = -EINVAL;
881 goto bad;
882 }
883
884 /* parse the priority groups */
885 while (as.argc) {
886 struct priority_group *pg;
887
888 pg = parse_priority_group(&as, m);
889 if (IS_ERR(pg)) {
890 r = PTR_ERR(pg);
891 goto bad;
892 }
893
894 m->nr_valid_paths += pg->nr_pgpaths;
895 list_add_tail(&pg->list, &m->priority_groups);
896 pg_count++;
897 pg->pg_num = pg_count;
898 if (!--next_pg_num)
899 m->next_pg = pg;
900 }
901
902 if (pg_count != m->nr_priority_groups) {
903 ti->error = "priority group count mismatch";
904 r = -EINVAL;
905 goto bad;
906 }
907
908 ti->num_flush_bios = 1;
909 ti->num_discard_bios = 1;
910 ti->num_write_same_bios = 1;
911 if (use_blk_mq)
912 ti->per_io_data_size = sizeof(struct dm_mpath_io);
913
914 return 0;
915
916 bad:
917 free_multipath(m);
918 return r;
919}
920
921static void multipath_wait_for_pg_init_completion(struct multipath *m)
922{
923 DECLARE_WAITQUEUE(wait, current);
924 unsigned long flags;
925
926 add_wait_queue(&m->pg_init_wait, &wait);
927
928 while (1) {
929 set_current_state(TASK_UNINTERRUPTIBLE);
930
931 spin_lock_irqsave(&m->lock, flags);
932 if (!m->pg_init_in_progress) {
933 spin_unlock_irqrestore(&m->lock, flags);
934 break;
935 }
936 spin_unlock_irqrestore(&m->lock, flags);
937
938 io_schedule();
939 }
940 set_current_state(TASK_RUNNING);
941
942 remove_wait_queue(&m->pg_init_wait, &wait);
943}
944
945static void flush_multipath_work(struct multipath *m)
946{
947 unsigned long flags;
948
949 spin_lock_irqsave(&m->lock, flags);
950 m->pg_init_disabled = true;
951 spin_unlock_irqrestore(&m->lock, flags);
952
953 flush_workqueue(kmpath_handlerd);
954 multipath_wait_for_pg_init_completion(m);
955 flush_workqueue(kmultipathd);
956 flush_work(&m->trigger_event);
957
958 spin_lock_irqsave(&m->lock, flags);
959 m->pg_init_disabled = false;
960 spin_unlock_irqrestore(&m->lock, flags);
961}
962
963static void multipath_dtr(struct dm_target *ti)
964{
965 struct multipath *m = ti->private;
966
967 flush_multipath_work(m);
968 free_multipath(m);
969}
970
971/*
972 * Take a path out of use.
973 */
974static int fail_path(struct pgpath *pgpath)
975{
976 unsigned long flags;
977 struct multipath *m = pgpath->pg->m;
978
979 spin_lock_irqsave(&m->lock, flags);
980
981 if (!pgpath->is_active)
982 goto out;
983
984 DMWARN("Failing path %s.", pgpath->path.dev->name);
985
986 pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
987 pgpath->is_active = false;
988 pgpath->fail_count++;
989
990 m->nr_valid_paths--;
991
992 if (pgpath == m->current_pgpath)
993 m->current_pgpath = NULL;
994
995 dm_path_uevent(DM_UEVENT_PATH_FAILED, m->ti,
996 pgpath->path.dev->name, m->nr_valid_paths);
997
998 schedule_work(&m->trigger_event);
999
1000out:
1001 spin_unlock_irqrestore(&m->lock, flags);
1002
1003 return 0;
1004}
1005
1006/*
1007 * Reinstate a previously-failed path
1008 */
1009static int reinstate_path(struct pgpath *pgpath)
1010{
1011 int r = 0, run_queue = 0;
1012 unsigned long flags;
1013 struct multipath *m = pgpath->pg->m;
1014
1015 spin_lock_irqsave(&m->lock, flags);
1016
1017 if (pgpath->is_active)
1018 goto out;
1019
1020 DMWARN("Reinstating path %s.", pgpath->path.dev->name);
1021
1022 r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
1023 if (r)
1024 goto out;
1025
1026 pgpath->is_active = true;
1027
1028 if (!m->nr_valid_paths++) {
1029 m->current_pgpath = NULL;
1030 run_queue = 1;
1031 } else if (m->hw_handler_name && (m->current_pg == pgpath->pg)) {
1032 if (queue_work(kmpath_handlerd, &pgpath->activate_path.work))
1033 m->pg_init_in_progress++;
1034 }
1035
1036 dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti,
1037 pgpath->path.dev->name, m->nr_valid_paths);
1038
1039 schedule_work(&m->trigger_event);
1040
1041out:
1042 spin_unlock_irqrestore(&m->lock, flags);
1043 if (run_queue)
1044 dm_table_run_md_queue_async(m->ti->table);
1045
1046 return r;
1047}
1048
1049/*
1050 * Fail or reinstate all paths that match the provided struct dm_dev.
1051 */
1052static int action_dev(struct multipath *m, struct dm_dev *dev,
1053 action_fn action)
1054{
1055 int r = -EINVAL;
1056 struct pgpath *pgpath;
1057 struct priority_group *pg;
1058
1059 list_for_each_entry(pg, &m->priority_groups, list) {
1060 list_for_each_entry(pgpath, &pg->pgpaths, list) {
1061 if (pgpath->path.dev == dev)
1062 r = action(pgpath);
1063 }
1064 }
1065
1066 return r;
1067}
1068
1069/*
1070 * Temporarily try to avoid having to use the specified PG
1071 */
1072static void bypass_pg(struct multipath *m, struct priority_group *pg,
1073 bool bypassed)
1074{
1075 unsigned long flags;
1076
1077 spin_lock_irqsave(&m->lock, flags);
1078
1079 pg->bypassed = bypassed;
1080 m->current_pgpath = NULL;
1081 m->current_pg = NULL;
1082
1083 spin_unlock_irqrestore(&m->lock, flags);
1084
1085 schedule_work(&m->trigger_event);
1086}
1087
1088/*
1089 * Switch to using the specified PG from the next I/O that gets mapped
1090 */
1091static int switch_pg_num(struct multipath *m, const char *pgstr)
1092{
1093 struct priority_group *pg;
1094 unsigned pgnum;
1095 unsigned long flags;
1096 char dummy;
1097
1098 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1099 (pgnum > m->nr_priority_groups)) {
1100 DMWARN("invalid PG number supplied to switch_pg_num");
1101 return -EINVAL;
1102 }
1103
1104 spin_lock_irqsave(&m->lock, flags);
1105 list_for_each_entry(pg, &m->priority_groups, list) {
1106 pg->bypassed = false;
1107 if (--pgnum)
1108 continue;
1109
1110 m->current_pgpath = NULL;
1111 m->current_pg = NULL;
1112 m->next_pg = pg;
1113 }
1114 spin_unlock_irqrestore(&m->lock, flags);
1115
1116 schedule_work(&m->trigger_event);
1117 return 0;
1118}
1119
1120/*
1121 * Set/clear bypassed status of a PG.
1122 * PGs are numbered upwards from 1 in the order they were declared.
1123 */
1124static int bypass_pg_num(struct multipath *m, const char *pgstr, bool bypassed)
1125{
1126 struct priority_group *pg;
1127 unsigned pgnum;
1128 char dummy;
1129
1130 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1131 (pgnum > m->nr_priority_groups)) {
1132 DMWARN("invalid PG number supplied to bypass_pg");
1133 return -EINVAL;
1134 }
1135
1136 list_for_each_entry(pg, &m->priority_groups, list) {
1137 if (!--pgnum)
1138 break;
1139 }
1140
1141 bypass_pg(m, pg, bypassed);
1142 return 0;
1143}
1144
1145/*
1146 * Should we retry pg_init immediately?
1147 */
1148static bool pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath)
1149{
1150 unsigned long flags;
1151 bool limit_reached = false;
1152
1153 spin_lock_irqsave(&m->lock, flags);
1154
1155 if (m->pg_init_count <= m->pg_init_retries && !m->pg_init_disabled)
1156 m->pg_init_required = true;
1157 else
1158 limit_reached = true;
1159
1160 spin_unlock_irqrestore(&m->lock, flags);
1161
1162 return limit_reached;
1163}
1164
1165static void pg_init_done(void *data, int errors)
1166{
1167 struct pgpath *pgpath = data;
1168 struct priority_group *pg = pgpath->pg;
1169 struct multipath *m = pg->m;
1170 unsigned long flags;
1171 bool delay_retry = false;
1172
1173 /* device or driver problems */
1174 switch (errors) {
1175 case SCSI_DH_OK:
1176 break;
1177 case SCSI_DH_NOSYS:
1178 if (!m->hw_handler_name) {
1179 errors = 0;
1180 break;
1181 }
1182 DMERR("Could not failover the device: Handler scsi_dh_%s "
1183 "Error %d.", m->hw_handler_name, errors);
1184 /*
1185 * Fail path for now, so we do not ping pong
1186 */
1187 fail_path(pgpath);
1188 break;
1189 case SCSI_DH_DEV_TEMP_BUSY:
1190 /*
1191 * Probably doing something like FW upgrade on the
1192 * controller so try the other pg.
1193 */
1194 bypass_pg(m, pg, true);
1195 break;
1196 case SCSI_DH_RETRY:
1197 /* Wait before retrying. */
1198 delay_retry = 1;
1199 case SCSI_DH_IMM_RETRY:
1200 case SCSI_DH_RES_TEMP_UNAVAIL:
1201 if (pg_init_limit_reached(m, pgpath))
1202 fail_path(pgpath);
1203 errors = 0;
1204 break;
1205 case SCSI_DH_DEV_OFFLINED:
1206 default:
1207 /*
1208 * We probably do not want to fail the path for a device
1209 * error, but this is what the old dm did. In future
1210 * patches we can do more advanced handling.
1211 */
1212 fail_path(pgpath);
1213 }
1214
1215 spin_lock_irqsave(&m->lock, flags);
1216 if (errors) {
1217 if (pgpath == m->current_pgpath) {
1218 DMERR("Could not failover device. Error %d.", errors);
1219 m->current_pgpath = NULL;
1220 m->current_pg = NULL;
1221 }
1222 } else if (!m->pg_init_required)
1223 pg->bypassed = false;
1224
1225 if (--m->pg_init_in_progress)
1226 /* Activations of other paths are still on going */
1227 goto out;
1228
1229 if (m->pg_init_required) {
1230 m->pg_init_delay_retry = delay_retry;
1231 if (__pg_init_all_paths(m))
1232 goto out;
1233 }
1234 m->queue_io = false;
1235
1236 /*
1237 * Wake up any thread waiting to suspend.
1238 */
1239 wake_up(&m->pg_init_wait);
1240
1241out:
1242 spin_unlock_irqrestore(&m->lock, flags);
1243}
1244
1245static void activate_path(struct work_struct *work)
1246{
1247 struct pgpath *pgpath =
1248 container_of(work, struct pgpath, activate_path.work);
1249
1250 if (pgpath->is_active)
1251 scsi_dh_activate(bdev_get_queue(pgpath->path.dev->bdev),
1252 pg_init_done, pgpath);
1253 else
1254 pg_init_done(pgpath, SCSI_DH_DEV_OFFLINED);
1255}
1256
1257static int noretry_error(int error)
1258{
1259 switch (error) {
1260 case -EOPNOTSUPP:
1261 case -EREMOTEIO:
1262 case -EILSEQ:
1263 case -ENODATA:
1264 case -ENOSPC:
1265 return 1;
1266 }
1267
1268 /* Anything else could be a path failure, so should be retried */
1269 return 0;
1270}
1271
1272/*
1273 * end_io handling
1274 */
1275static int do_end_io(struct multipath *m, struct request *clone,
1276 int error, struct dm_mpath_io *mpio)
1277{
1278 /*
1279 * We don't queue any clone request inside the multipath target
1280 * during end I/O handling, since those clone requests don't have
1281 * bio clones. If we queue them inside the multipath target,
1282 * we need to make bio clones, that requires memory allocation.
1283 * (See drivers/md/dm.c:end_clone_bio() about why the clone requests
1284 * don't have bio clones.)
1285 * Instead of queueing the clone request here, we queue the original
1286 * request into dm core, which will remake a clone request and
1287 * clone bios for it and resubmit it later.
1288 */
1289 int r = DM_ENDIO_REQUEUE;
1290 unsigned long flags;
1291
1292 if (!error && !clone->errors)
1293 return 0; /* I/O complete */
1294
1295 if (noretry_error(error))
1296 return error;
1297
1298 if (mpio->pgpath)
1299 fail_path(mpio->pgpath);
1300
1301 spin_lock_irqsave(&m->lock, flags);
1302 if (!m->nr_valid_paths) {
1303 if (!m->queue_if_no_path) {
1304 if (!__must_push_back(m))
1305 r = -EIO;
1306 } else {
1307 if (error == -EBADE)
1308 r = error;
1309 }
1310 }
1311 spin_unlock_irqrestore(&m->lock, flags);
1312
1313 return r;
1314}
1315
1316static int multipath_end_io(struct dm_target *ti, struct request *clone,
1317 int error, union map_info *map_context)
1318{
1319 struct multipath *m = ti->private;
1320 struct dm_mpath_io *mpio = get_mpio(map_context);
1321 struct pgpath *pgpath;
1322 struct path_selector *ps;
1323 int r;
1324
1325 BUG_ON(!mpio);
1326
1327 r = do_end_io(m, clone, error, mpio);
1328 pgpath = mpio->pgpath;
1329 if (pgpath) {
1330 ps = &pgpath->pg->ps;
1331 if (ps->type->end_io)
1332 ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
1333 }
1334 clear_request_fn_mpio(m, map_context);
1335
1336 return r;
1337}
1338
1339/*
1340 * Suspend can't complete until all the I/O is processed so if
1341 * the last path fails we must error any remaining I/O.
1342 * Note that if the freeze_bdev fails while suspending, the
1343 * queue_if_no_path state is lost - userspace should reset it.
1344 */
1345static void multipath_presuspend(struct dm_target *ti)
1346{
1347 struct multipath *m = ti->private;
1348
1349 queue_if_no_path(m, false, true);
1350}
1351
1352static void multipath_postsuspend(struct dm_target *ti)
1353{
1354 struct multipath *m = ti->private;
1355
1356 mutex_lock(&m->work_mutex);
1357 flush_multipath_work(m);
1358 mutex_unlock(&m->work_mutex);
1359}
1360
1361/*
1362 * Restore the queue_if_no_path setting.
1363 */
1364static void multipath_resume(struct dm_target *ti)
1365{
1366 struct multipath *m = ti->private;
1367 unsigned long flags;
1368
1369 spin_lock_irqsave(&m->lock, flags);
1370 m->queue_if_no_path = m->saved_queue_if_no_path;
1371 spin_unlock_irqrestore(&m->lock, flags);
1372}
1373
1374/*
1375 * Info output has the following format:
1376 * num_multipath_feature_args [multipath_feature_args]*
1377 * num_handler_status_args [handler_status_args]*
1378 * num_groups init_group_number
1379 * [A|D|E num_ps_status_args [ps_status_args]*
1380 * num_paths num_selector_args
1381 * [path_dev A|F fail_count [selector_args]* ]+ ]+
1382 *
1383 * Table output has the following format (identical to the constructor string):
1384 * num_feature_args [features_args]*
1385 * num_handler_args hw_handler [hw_handler_args]*
1386 * num_groups init_group_number
1387 * [priority selector-name num_ps_args [ps_args]*
1388 * num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
1389 */
1390static void multipath_status(struct dm_target *ti, status_type_t type,
1391 unsigned status_flags, char *result, unsigned maxlen)
1392{
1393 int sz = 0;
1394 unsigned long flags;
1395 struct multipath *m = ti->private;
1396 struct priority_group *pg;
1397 struct pgpath *p;
1398 unsigned pg_num;
1399 char state;
1400
1401 spin_lock_irqsave(&m->lock, flags);
1402
1403 /* Features */
1404 if (type == STATUSTYPE_INFO)
1405 DMEMIT("2 %u %u ", m->queue_io, m->pg_init_count);
1406 else {
1407 DMEMIT("%u ", m->queue_if_no_path +
1408 (m->pg_init_retries > 0) * 2 +
1409 (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT) * 2 +
1410 m->retain_attached_hw_handler);
1411 if (m->queue_if_no_path)
1412 DMEMIT("queue_if_no_path ");
1413 if (m->pg_init_retries)
1414 DMEMIT("pg_init_retries %u ", m->pg_init_retries);
1415 if (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT)
1416 DMEMIT("pg_init_delay_msecs %u ", m->pg_init_delay_msecs);
1417 if (m->retain_attached_hw_handler)
1418 DMEMIT("retain_attached_hw_handler ");
1419 }
1420
1421 if (!m->hw_handler_name || type == STATUSTYPE_INFO)
1422 DMEMIT("0 ");
1423 else
1424 DMEMIT("1 %s ", m->hw_handler_name);
1425
1426 DMEMIT("%u ", m->nr_priority_groups);
1427
1428 if (m->next_pg)
1429 pg_num = m->next_pg->pg_num;
1430 else if (m->current_pg)
1431 pg_num = m->current_pg->pg_num;
1432 else
1433 pg_num = (m->nr_priority_groups ? 1 : 0);
1434
1435 DMEMIT("%u ", pg_num);
1436
1437 switch (type) {
1438 case STATUSTYPE_INFO:
1439 list_for_each_entry(pg, &m->priority_groups, list) {
1440 if (pg->bypassed)
1441 state = 'D'; /* Disabled */
1442 else if (pg == m->current_pg)
1443 state = 'A'; /* Currently Active */
1444 else
1445 state = 'E'; /* Enabled */
1446
1447 DMEMIT("%c ", state);
1448
1449 if (pg->ps.type->status)
1450 sz += pg->ps.type->status(&pg->ps, NULL, type,
1451 result + sz,
1452 maxlen - sz);
1453 else
1454 DMEMIT("0 ");
1455
1456 DMEMIT("%u %u ", pg->nr_pgpaths,
1457 pg->ps.type->info_args);
1458
1459 list_for_each_entry(p, &pg->pgpaths, list) {
1460 DMEMIT("%s %s %u ", p->path.dev->name,
1461 p->is_active ? "A" : "F",
1462 p->fail_count);
1463 if (pg->ps.type->status)
1464 sz += pg->ps.type->status(&pg->ps,
1465 &p->path, type, result + sz,
1466 maxlen - sz);
1467 }
1468 }
1469 break;
1470
1471 case STATUSTYPE_TABLE:
1472 list_for_each_entry(pg, &m->priority_groups, list) {
1473 DMEMIT("%s ", pg->ps.type->name);
1474
1475 if (pg->ps.type->status)
1476 sz += pg->ps.type->status(&pg->ps, NULL, type,
1477 result + sz,
1478 maxlen - sz);
1479 else
1480 DMEMIT("0 ");
1481
1482 DMEMIT("%u %u ", pg->nr_pgpaths,
1483 pg->ps.type->table_args);
1484
1485 list_for_each_entry(p, &pg->pgpaths, list) {
1486 DMEMIT("%s ", p->path.dev->name);
1487 if (pg->ps.type->status)
1488 sz += pg->ps.type->status(&pg->ps,
1489 &p->path, type, result + sz,
1490 maxlen - sz);
1491 }
1492 }
1493 break;
1494 }
1495
1496 spin_unlock_irqrestore(&m->lock, flags);
1497}
1498
1499static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
1500{
1501 int r = -EINVAL;
1502 struct dm_dev *dev;
1503 struct multipath *m = ti->private;
1504 action_fn action;
1505
1506 mutex_lock(&m->work_mutex);
1507
1508 if (dm_suspended(ti)) {
1509 r = -EBUSY;
1510 goto out;
1511 }
1512
1513 if (argc == 1) {
1514 if (!strcasecmp(argv[0], "queue_if_no_path")) {
1515 r = queue_if_no_path(m, true, false);
1516 goto out;
1517 } else if (!strcasecmp(argv[0], "fail_if_no_path")) {
1518 r = queue_if_no_path(m, false, false);
1519 goto out;
1520 }
1521 }
1522
1523 if (argc != 2) {
1524 DMWARN("Invalid multipath message arguments. Expected 2 arguments, got %d.", argc);
1525 goto out;
1526 }
1527
1528 if (!strcasecmp(argv[0], "disable_group")) {
1529 r = bypass_pg_num(m, argv[1], true);
1530 goto out;
1531 } else if (!strcasecmp(argv[0], "enable_group")) {
1532 r = bypass_pg_num(m, argv[1], false);
1533 goto out;
1534 } else if (!strcasecmp(argv[0], "switch_group")) {
1535 r = switch_pg_num(m, argv[1]);
1536 goto out;
1537 } else if (!strcasecmp(argv[0], "reinstate_path"))
1538 action = reinstate_path;
1539 else if (!strcasecmp(argv[0], "fail_path"))
1540 action = fail_path;
1541 else {
1542 DMWARN("Unrecognised multipath message received: %s", argv[0]);
1543 goto out;
1544 }
1545
1546 r = dm_get_device(ti, argv[1], dm_table_get_mode(ti->table), &dev);
1547 if (r) {
1548 DMWARN("message: error getting device %s",
1549 argv[1]);
1550 goto out;
1551 }
1552
1553 r = action_dev(m, dev, action);
1554
1555 dm_put_device(ti, dev);
1556
1557out:
1558 mutex_unlock(&m->work_mutex);
1559 return r;
1560}
1561
1562static int multipath_prepare_ioctl(struct dm_target *ti,
1563 struct block_device **bdev, fmode_t *mode)
1564{
1565 struct multipath *m = ti->private;
1566 unsigned long flags;
1567 int r;
1568
1569 spin_lock_irqsave(&m->lock, flags);
1570
1571 if (!m->current_pgpath)
1572 __choose_pgpath(m, 0);
1573
1574 if (m->current_pgpath) {
1575 if (!m->queue_io) {
1576 *bdev = m->current_pgpath->path.dev->bdev;
1577 *mode = m->current_pgpath->path.dev->mode;
1578 r = 0;
1579 } else {
1580 /* pg_init has not started or completed */
1581 r = -ENOTCONN;
1582 }
1583 } else {
1584 /* No path is available */
1585 if (m->queue_if_no_path)
1586 r = -ENOTCONN;
1587 else
1588 r = -EIO;
1589 }
1590
1591 spin_unlock_irqrestore(&m->lock, flags);
1592
1593 if (r == -ENOTCONN) {
1594 spin_lock_irqsave(&m->lock, flags);
1595 if (!m->current_pg) {
1596 /* Path status changed, redo selection */
1597 __choose_pgpath(m, 0);
1598 }
1599 if (m->pg_init_required)
1600 __pg_init_all_paths(m);
1601 spin_unlock_irqrestore(&m->lock, flags);
1602 dm_table_run_md_queue_async(m->ti->table);
1603 }
1604
1605 /*
1606 * Only pass ioctls through if the device sizes match exactly.
1607 */
1608 if (!r && ti->len != i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT)
1609 return 1;
1610 return r;
1611}
1612
1613static int multipath_iterate_devices(struct dm_target *ti,
1614 iterate_devices_callout_fn fn, void *data)
1615{
1616 struct multipath *m = ti->private;
1617 struct priority_group *pg;
1618 struct pgpath *p;
1619 int ret = 0;
1620
1621 list_for_each_entry(pg, &m->priority_groups, list) {
1622 list_for_each_entry(p, &pg->pgpaths, list) {
1623 ret = fn(ti, p->path.dev, ti->begin, ti->len, data);
1624 if (ret)
1625 goto out;
1626 }
1627 }
1628
1629out:
1630 return ret;
1631}
1632
1633static int pgpath_busy(struct pgpath *pgpath)
1634{
1635 struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
1636
1637 return blk_lld_busy(q);
1638}
1639
1640/*
1641 * We return "busy", only when we can map I/Os but underlying devices
1642 * are busy (so even if we map I/Os now, the I/Os will wait on
1643 * the underlying queue).
1644 * In other words, if we want to kill I/Os or queue them inside us
1645 * due to map unavailability, we don't return "busy". Otherwise,
1646 * dm core won't give us the I/Os and we can't do what we want.
1647 */
1648static int multipath_busy(struct dm_target *ti)
1649{
1650 bool busy = false, has_active = false;
1651 struct multipath *m = ti->private;
1652 struct priority_group *pg;
1653 struct pgpath *pgpath;
1654 unsigned long flags;
1655
1656 spin_lock_irqsave(&m->lock, flags);
1657
1658 /* pg_init in progress or no paths available */
1659 if (m->pg_init_in_progress ||
1660 (!m->nr_valid_paths && m->queue_if_no_path)) {
1661 busy = true;
1662 goto out;
1663 }
1664 /* Guess which priority_group will be used at next mapping time */
1665 if (unlikely(!m->current_pgpath && m->next_pg))
1666 pg = m->next_pg;
1667 else if (likely(m->current_pg))
1668 pg = m->current_pg;
1669 else
1670 /*
1671 * We don't know which pg will be used at next mapping time.
1672 * We don't call __choose_pgpath() here to avoid to trigger
1673 * pg_init just by busy checking.
1674 * So we don't know whether underlying devices we will be using
1675 * at next mapping time are busy or not. Just try mapping.
1676 */
1677 goto out;
1678
1679 /*
1680 * If there is one non-busy active path at least, the path selector
1681 * will be able to select it. So we consider such a pg as not busy.
1682 */
1683 busy = true;
1684 list_for_each_entry(pgpath, &pg->pgpaths, list)
1685 if (pgpath->is_active) {
1686 has_active = true;
1687 if (!pgpath_busy(pgpath)) {
1688 busy = false;
1689 break;
1690 }
1691 }
1692
1693 if (!has_active)
1694 /*
1695 * No active path in this pg, so this pg won't be used and
1696 * the current_pg will be changed at next mapping time.
1697 * We need to try mapping to determine it.
1698 */
1699 busy = false;
1700
1701out:
1702 spin_unlock_irqrestore(&m->lock, flags);
1703
1704 return busy;
1705}
1706
1707/*-----------------------------------------------------------------
1708 * Module setup
1709 *---------------------------------------------------------------*/
1710static struct target_type multipath_target = {
1711 .name = "multipath",
1712 .version = {1, 11, 0},
1713 .features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE,
1714 .module = THIS_MODULE,
1715 .ctr = multipath_ctr,
1716 .dtr = multipath_dtr,
1717 .map_rq = multipath_map,
1718 .clone_and_map_rq = multipath_clone_and_map,
1719 .release_clone_rq = multipath_release_clone,
1720 .rq_end_io = multipath_end_io,
1721 .presuspend = multipath_presuspend,
1722 .postsuspend = multipath_postsuspend,
1723 .resume = multipath_resume,
1724 .status = multipath_status,
1725 .message = multipath_message,
1726 .prepare_ioctl = multipath_prepare_ioctl,
1727 .iterate_devices = multipath_iterate_devices,
1728 .busy = multipath_busy,
1729};
1730
1731static int __init dm_multipath_init(void)
1732{
1733 int r;
1734
1735 /* allocate a slab for the dm_ios */
1736 _mpio_cache = KMEM_CACHE(dm_mpath_io, 0);
1737 if (!_mpio_cache)
1738 return -ENOMEM;
1739
1740 r = dm_register_target(&multipath_target);
1741 if (r < 0) {
1742 DMERR("register failed %d", r);
1743 r = -EINVAL;
1744 goto bad_register_target;
1745 }
1746
1747 kmultipathd = alloc_workqueue("kmpathd", WQ_MEM_RECLAIM, 0);
1748 if (!kmultipathd) {
1749 DMERR("failed to create workqueue kmpathd");
1750 r = -ENOMEM;
1751 goto bad_alloc_kmultipathd;
1752 }
1753
1754 /*
1755 * A separate workqueue is used to handle the device handlers
1756 * to avoid overloading existing workqueue. Overloading the
1757 * old workqueue would also create a bottleneck in the
1758 * path of the storage hardware device activation.
1759 */
1760 kmpath_handlerd = alloc_ordered_workqueue("kmpath_handlerd",
1761 WQ_MEM_RECLAIM);
1762 if (!kmpath_handlerd) {
1763 DMERR("failed to create workqueue kmpath_handlerd");
1764 r = -ENOMEM;
1765 goto bad_alloc_kmpath_handlerd;
1766 }
1767
1768 DMINFO("version %u.%u.%u loaded",
1769 multipath_target.version[0], multipath_target.version[1],
1770 multipath_target.version[2]);
1771
1772 return 0;
1773
1774bad_alloc_kmpath_handlerd:
1775 destroy_workqueue(kmultipathd);
1776bad_alloc_kmultipathd:
1777 dm_unregister_target(&multipath_target);
1778bad_register_target:
1779 kmem_cache_destroy(_mpio_cache);
1780
1781 return r;
1782}
1783
1784static void __exit dm_multipath_exit(void)
1785{
1786 destroy_workqueue(kmpath_handlerd);
1787 destroy_workqueue(kmultipathd);
1788
1789 dm_unregister_target(&multipath_target);
1790 kmem_cache_destroy(_mpio_cache);
1791}
1792
1793module_init(dm_multipath_init);
1794module_exit(dm_multipath_exit);
1795
1796MODULE_DESCRIPTION(DM_NAME " multipath target");
1797MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
1798MODULE_LICENSE("GPL");
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-path-selector.h"
11#include "dm-uevent.h"
12
13#include <linux/ctype.h>
14#include <linux/init.h>
15#include <linux/mempool.h>
16#include <linux/module.h>
17#include <linux/pagemap.h>
18#include <linux/slab.h>
19#include <linux/time.h>
20#include <linux/workqueue.h>
21#include <linux/delay.h>
22#include <scsi/scsi_dh.h>
23#include <linux/atomic.h>
24
25#define DM_MSG_PREFIX "multipath"
26#define DM_PG_INIT_DELAY_MSECS 2000
27#define DM_PG_INIT_DELAY_DEFAULT ((unsigned) -1)
28
29/* Path properties */
30struct pgpath {
31 struct list_head list;
32
33 struct priority_group *pg; /* Owning PG */
34 unsigned is_active; /* Path status */
35 unsigned fail_count; /* Cumulative failure count */
36
37 struct dm_path path;
38 struct delayed_work activate_path;
39};
40
41#define path_to_pgpath(__pgp) container_of((__pgp), struct pgpath, path)
42
43/*
44 * Paths are grouped into Priority Groups and numbered from 1 upwards.
45 * Each has a path selector which controls which path gets used.
46 */
47struct priority_group {
48 struct list_head list;
49
50 struct multipath *m; /* Owning multipath instance */
51 struct path_selector ps;
52
53 unsigned pg_num; /* Reference number */
54 unsigned bypassed; /* Temporarily bypass this PG? */
55
56 unsigned nr_pgpaths; /* Number of paths in PG */
57 struct list_head pgpaths;
58};
59
60/* Multipath context */
61struct multipath {
62 struct list_head list;
63 struct dm_target *ti;
64
65 const char *hw_handler_name;
66 char *hw_handler_params;
67
68 spinlock_t lock;
69
70 unsigned nr_priority_groups;
71 struct list_head priority_groups;
72
73 wait_queue_head_t pg_init_wait; /* Wait for pg_init completion */
74
75 unsigned pg_init_required; /* pg_init needs calling? */
76 unsigned pg_init_in_progress; /* Only one pg_init allowed at once */
77 unsigned pg_init_delay_retry; /* Delay pg_init retry? */
78
79 unsigned nr_valid_paths; /* Total number of usable paths */
80 struct pgpath *current_pgpath;
81 struct priority_group *current_pg;
82 struct priority_group *next_pg; /* Switch to this PG if set */
83 unsigned repeat_count; /* I/Os left before calling PS again */
84
85 unsigned queue_io:1; /* Must we queue all I/O? */
86 unsigned queue_if_no_path:1; /* Queue I/O if last path fails? */
87 unsigned saved_queue_if_no_path:1; /* Saved state during suspension */
88
89 unsigned pg_init_retries; /* Number of times to retry pg_init */
90 unsigned pg_init_count; /* Number of times pg_init called */
91 unsigned pg_init_delay_msecs; /* Number of msecs before pg_init retry */
92
93 unsigned queue_size;
94 struct work_struct process_queued_ios;
95 struct list_head queued_ios;
96
97 struct work_struct trigger_event;
98
99 /*
100 * We must use a mempool of dm_mpath_io structs so that we
101 * can resubmit bios on error.
102 */
103 mempool_t *mpio_pool;
104
105 struct mutex work_mutex;
106};
107
108/*
109 * Context information attached to each bio we process.
110 */
111struct dm_mpath_io {
112 struct pgpath *pgpath;
113 size_t nr_bytes;
114};
115
116typedef int (*action_fn) (struct pgpath *pgpath);
117
118#define MIN_IOS 256 /* Mempool size */
119
120static struct kmem_cache *_mpio_cache;
121
122static struct workqueue_struct *kmultipathd, *kmpath_handlerd;
123static void process_queued_ios(struct work_struct *work);
124static void trigger_event(struct work_struct *work);
125static void activate_path(struct work_struct *work);
126
127
128/*-----------------------------------------------
129 * Allocation routines
130 *-----------------------------------------------*/
131
132static struct pgpath *alloc_pgpath(void)
133{
134 struct pgpath *pgpath = kzalloc(sizeof(*pgpath), GFP_KERNEL);
135
136 if (pgpath) {
137 pgpath->is_active = 1;
138 INIT_DELAYED_WORK(&pgpath->activate_path, activate_path);
139 }
140
141 return pgpath;
142}
143
144static void free_pgpath(struct pgpath *pgpath)
145{
146 kfree(pgpath);
147}
148
149static struct priority_group *alloc_priority_group(void)
150{
151 struct priority_group *pg;
152
153 pg = kzalloc(sizeof(*pg), GFP_KERNEL);
154
155 if (pg)
156 INIT_LIST_HEAD(&pg->pgpaths);
157
158 return pg;
159}
160
161static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti)
162{
163 struct pgpath *pgpath, *tmp;
164 struct multipath *m = ti->private;
165
166 list_for_each_entry_safe(pgpath, tmp, pgpaths, list) {
167 list_del(&pgpath->list);
168 if (m->hw_handler_name)
169 scsi_dh_detach(bdev_get_queue(pgpath->path.dev->bdev));
170 dm_put_device(ti, pgpath->path.dev);
171 free_pgpath(pgpath);
172 }
173}
174
175static void free_priority_group(struct priority_group *pg,
176 struct dm_target *ti)
177{
178 struct path_selector *ps = &pg->ps;
179
180 if (ps->type) {
181 ps->type->destroy(ps);
182 dm_put_path_selector(ps->type);
183 }
184
185 free_pgpaths(&pg->pgpaths, ti);
186 kfree(pg);
187}
188
189static struct multipath *alloc_multipath(struct dm_target *ti)
190{
191 struct multipath *m;
192
193 m = kzalloc(sizeof(*m), GFP_KERNEL);
194 if (m) {
195 INIT_LIST_HEAD(&m->priority_groups);
196 INIT_LIST_HEAD(&m->queued_ios);
197 spin_lock_init(&m->lock);
198 m->queue_io = 1;
199 m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT;
200 INIT_WORK(&m->process_queued_ios, process_queued_ios);
201 INIT_WORK(&m->trigger_event, trigger_event);
202 init_waitqueue_head(&m->pg_init_wait);
203 mutex_init(&m->work_mutex);
204 m->mpio_pool = mempool_create_slab_pool(MIN_IOS, _mpio_cache);
205 if (!m->mpio_pool) {
206 kfree(m);
207 return NULL;
208 }
209 m->ti = ti;
210 ti->private = m;
211 }
212
213 return m;
214}
215
216static void free_multipath(struct multipath *m)
217{
218 struct priority_group *pg, *tmp;
219
220 list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) {
221 list_del(&pg->list);
222 free_priority_group(pg, m->ti);
223 }
224
225 kfree(m->hw_handler_name);
226 kfree(m->hw_handler_params);
227 mempool_destroy(m->mpio_pool);
228 kfree(m);
229}
230
231static int set_mapinfo(struct multipath *m, union map_info *info)
232{
233 struct dm_mpath_io *mpio;
234
235 mpio = mempool_alloc(m->mpio_pool, GFP_ATOMIC);
236 if (!mpio)
237 return -ENOMEM;
238
239 memset(mpio, 0, sizeof(*mpio));
240 info->ptr = mpio;
241
242 return 0;
243}
244
245static void clear_mapinfo(struct multipath *m, union map_info *info)
246{
247 struct dm_mpath_io *mpio = info->ptr;
248
249 info->ptr = NULL;
250 mempool_free(mpio, m->mpio_pool);
251}
252
253/*-----------------------------------------------
254 * Path selection
255 *-----------------------------------------------*/
256
257static void __pg_init_all_paths(struct multipath *m)
258{
259 struct pgpath *pgpath;
260 unsigned long pg_init_delay = 0;
261
262 m->pg_init_count++;
263 m->pg_init_required = 0;
264 if (m->pg_init_delay_retry)
265 pg_init_delay = msecs_to_jiffies(m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT ?
266 m->pg_init_delay_msecs : DM_PG_INIT_DELAY_MSECS);
267 list_for_each_entry(pgpath, &m->current_pg->pgpaths, list) {
268 /* Skip failed paths */
269 if (!pgpath->is_active)
270 continue;
271 if (queue_delayed_work(kmpath_handlerd, &pgpath->activate_path,
272 pg_init_delay))
273 m->pg_init_in_progress++;
274 }
275}
276
277static void __switch_pg(struct multipath *m, struct pgpath *pgpath)
278{
279 m->current_pg = pgpath->pg;
280
281 /* Must we initialise the PG first, and queue I/O till it's ready? */
282 if (m->hw_handler_name) {
283 m->pg_init_required = 1;
284 m->queue_io = 1;
285 } else {
286 m->pg_init_required = 0;
287 m->queue_io = 0;
288 }
289
290 m->pg_init_count = 0;
291}
292
293static int __choose_path_in_pg(struct multipath *m, struct priority_group *pg,
294 size_t nr_bytes)
295{
296 struct dm_path *path;
297
298 path = pg->ps.type->select_path(&pg->ps, &m->repeat_count, nr_bytes);
299 if (!path)
300 return -ENXIO;
301
302 m->current_pgpath = path_to_pgpath(path);
303
304 if (m->current_pg != pg)
305 __switch_pg(m, m->current_pgpath);
306
307 return 0;
308}
309
310static void __choose_pgpath(struct multipath *m, size_t nr_bytes)
311{
312 struct priority_group *pg;
313 unsigned bypassed = 1;
314
315 if (!m->nr_valid_paths)
316 goto failed;
317
318 /* Were we instructed to switch PG? */
319 if (m->next_pg) {
320 pg = m->next_pg;
321 m->next_pg = NULL;
322 if (!__choose_path_in_pg(m, pg, nr_bytes))
323 return;
324 }
325
326 /* Don't change PG until it has no remaining paths */
327 if (m->current_pg && !__choose_path_in_pg(m, m->current_pg, nr_bytes))
328 return;
329
330 /*
331 * Loop through priority groups until we find a valid path.
332 * First time we skip PGs marked 'bypassed'.
333 * Second time we only try the ones we skipped, but set
334 * pg_init_delay_retry so we do not hammer controllers.
335 */
336 do {
337 list_for_each_entry(pg, &m->priority_groups, list) {
338 if (pg->bypassed == bypassed)
339 continue;
340 if (!__choose_path_in_pg(m, pg, nr_bytes)) {
341 if (!bypassed)
342 m->pg_init_delay_retry = 1;
343 return;
344 }
345 }
346 } while (bypassed--);
347
348failed:
349 m->current_pgpath = NULL;
350 m->current_pg = NULL;
351}
352
353/*
354 * Check whether bios must be queued in the device-mapper core rather
355 * than here in the target.
356 *
357 * m->lock must be held on entry.
358 *
359 * If m->queue_if_no_path and m->saved_queue_if_no_path hold the
360 * same value then we are not between multipath_presuspend()
361 * and multipath_resume() calls and we have no need to check
362 * for the DMF_NOFLUSH_SUSPENDING flag.
363 */
364static int __must_push_back(struct multipath *m)
365{
366 return (m->queue_if_no_path != m->saved_queue_if_no_path &&
367 dm_noflush_suspending(m->ti));
368}
369
370static int map_io(struct multipath *m, struct request *clone,
371 union map_info *map_context, unsigned was_queued)
372{
373 int r = DM_MAPIO_REMAPPED;
374 size_t nr_bytes = blk_rq_bytes(clone);
375 unsigned long flags;
376 struct pgpath *pgpath;
377 struct block_device *bdev;
378 struct dm_mpath_io *mpio = map_context->ptr;
379
380 spin_lock_irqsave(&m->lock, flags);
381
382 /* Do we need to select a new pgpath? */
383 if (!m->current_pgpath ||
384 (!m->queue_io && (m->repeat_count && --m->repeat_count == 0)))
385 __choose_pgpath(m, nr_bytes);
386
387 pgpath = m->current_pgpath;
388
389 if (was_queued)
390 m->queue_size--;
391
392 if ((pgpath && m->queue_io) ||
393 (!pgpath && m->queue_if_no_path)) {
394 /* Queue for the daemon to resubmit */
395 list_add_tail(&clone->queuelist, &m->queued_ios);
396 m->queue_size++;
397 if ((m->pg_init_required && !m->pg_init_in_progress) ||
398 !m->queue_io)
399 queue_work(kmultipathd, &m->process_queued_ios);
400 pgpath = NULL;
401 r = DM_MAPIO_SUBMITTED;
402 } else if (pgpath) {
403 bdev = pgpath->path.dev->bdev;
404 clone->q = bdev_get_queue(bdev);
405 clone->rq_disk = bdev->bd_disk;
406 } else if (__must_push_back(m))
407 r = DM_MAPIO_REQUEUE;
408 else
409 r = -EIO; /* Failed */
410
411 mpio->pgpath = pgpath;
412 mpio->nr_bytes = nr_bytes;
413
414 if (r == DM_MAPIO_REMAPPED && pgpath->pg->ps.type->start_io)
415 pgpath->pg->ps.type->start_io(&pgpath->pg->ps, &pgpath->path,
416 nr_bytes);
417
418 spin_unlock_irqrestore(&m->lock, flags);
419
420 return r;
421}
422
423/*
424 * If we run out of usable paths, should we queue I/O or error it?
425 */
426static int queue_if_no_path(struct multipath *m, unsigned queue_if_no_path,
427 unsigned save_old_value)
428{
429 unsigned long flags;
430
431 spin_lock_irqsave(&m->lock, flags);
432
433 if (save_old_value)
434 m->saved_queue_if_no_path = m->queue_if_no_path;
435 else
436 m->saved_queue_if_no_path = queue_if_no_path;
437 m->queue_if_no_path = queue_if_no_path;
438 if (!m->queue_if_no_path && m->queue_size)
439 queue_work(kmultipathd, &m->process_queued_ios);
440
441 spin_unlock_irqrestore(&m->lock, flags);
442
443 return 0;
444}
445
446/*-----------------------------------------------------------------
447 * The multipath daemon is responsible for resubmitting queued ios.
448 *---------------------------------------------------------------*/
449
450static void dispatch_queued_ios(struct multipath *m)
451{
452 int r;
453 unsigned long flags;
454 union map_info *info;
455 struct request *clone, *n;
456 LIST_HEAD(cl);
457
458 spin_lock_irqsave(&m->lock, flags);
459 list_splice_init(&m->queued_ios, &cl);
460 spin_unlock_irqrestore(&m->lock, flags);
461
462 list_for_each_entry_safe(clone, n, &cl, queuelist) {
463 list_del_init(&clone->queuelist);
464
465 info = dm_get_rq_mapinfo(clone);
466
467 r = map_io(m, clone, info, 1);
468 if (r < 0) {
469 clear_mapinfo(m, info);
470 dm_kill_unmapped_request(clone, r);
471 } else if (r == DM_MAPIO_REMAPPED)
472 dm_dispatch_request(clone);
473 else if (r == DM_MAPIO_REQUEUE) {
474 clear_mapinfo(m, info);
475 dm_requeue_unmapped_request(clone);
476 }
477 }
478}
479
480static void process_queued_ios(struct work_struct *work)
481{
482 struct multipath *m =
483 container_of(work, struct multipath, process_queued_ios);
484 struct pgpath *pgpath = NULL;
485 unsigned must_queue = 1;
486 unsigned long flags;
487
488 spin_lock_irqsave(&m->lock, flags);
489
490 if (!m->current_pgpath)
491 __choose_pgpath(m, 0);
492
493 pgpath = m->current_pgpath;
494
495 if ((pgpath && !m->queue_io) ||
496 (!pgpath && !m->queue_if_no_path))
497 must_queue = 0;
498
499 if (m->pg_init_required && !m->pg_init_in_progress && pgpath)
500 __pg_init_all_paths(m);
501
502 spin_unlock_irqrestore(&m->lock, flags);
503 if (!must_queue)
504 dispatch_queued_ios(m);
505}
506
507/*
508 * An event is triggered whenever a path is taken out of use.
509 * Includes path failure and PG bypass.
510 */
511static void trigger_event(struct work_struct *work)
512{
513 struct multipath *m =
514 container_of(work, struct multipath, trigger_event);
515
516 dm_table_event(m->ti->table);
517}
518
519/*-----------------------------------------------------------------
520 * Constructor/argument parsing:
521 * <#multipath feature args> [<arg>]*
522 * <#hw_handler args> [hw_handler [<arg>]*]
523 * <#priority groups>
524 * <initial priority group>
525 * [<selector> <#selector args> [<arg>]*
526 * <#paths> <#per-path selector args>
527 * [<path> [<arg>]* ]+ ]+
528 *---------------------------------------------------------------*/
529static int parse_path_selector(struct dm_arg_set *as, struct priority_group *pg,
530 struct dm_target *ti)
531{
532 int r;
533 struct path_selector_type *pst;
534 unsigned ps_argc;
535
536 static struct dm_arg _args[] = {
537 {0, 1024, "invalid number of path selector args"},
538 };
539
540 pst = dm_get_path_selector(dm_shift_arg(as));
541 if (!pst) {
542 ti->error = "unknown path selector type";
543 return -EINVAL;
544 }
545
546 r = dm_read_arg_group(_args, as, &ps_argc, &ti->error);
547 if (r) {
548 dm_put_path_selector(pst);
549 return -EINVAL;
550 }
551
552 r = pst->create(&pg->ps, ps_argc, as->argv);
553 if (r) {
554 dm_put_path_selector(pst);
555 ti->error = "path selector constructor failed";
556 return r;
557 }
558
559 pg->ps.type = pst;
560 dm_consume_args(as, ps_argc);
561
562 return 0;
563}
564
565static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps,
566 struct dm_target *ti)
567{
568 int r;
569 struct pgpath *p;
570 struct multipath *m = ti->private;
571
572 /* we need at least a path arg */
573 if (as->argc < 1) {
574 ti->error = "no device given";
575 return ERR_PTR(-EINVAL);
576 }
577
578 p = alloc_pgpath();
579 if (!p)
580 return ERR_PTR(-ENOMEM);
581
582 r = dm_get_device(ti, dm_shift_arg(as), dm_table_get_mode(ti->table),
583 &p->path.dev);
584 if (r) {
585 ti->error = "error getting device";
586 goto bad;
587 }
588
589 if (m->hw_handler_name) {
590 struct request_queue *q = bdev_get_queue(p->path.dev->bdev);
591
592 r = scsi_dh_attach(q, m->hw_handler_name);
593 if (r == -EBUSY) {
594 /*
595 * Already attached to different hw_handler,
596 * try to reattach with correct one.
597 */
598 scsi_dh_detach(q);
599 r = scsi_dh_attach(q, m->hw_handler_name);
600 }
601
602 if (r < 0) {
603 ti->error = "error attaching hardware handler";
604 dm_put_device(ti, p->path.dev);
605 goto bad;
606 }
607
608 if (m->hw_handler_params) {
609 r = scsi_dh_set_params(q, m->hw_handler_params);
610 if (r < 0) {
611 ti->error = "unable to set hardware "
612 "handler parameters";
613 scsi_dh_detach(q);
614 dm_put_device(ti, p->path.dev);
615 goto bad;
616 }
617 }
618 }
619
620 r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
621 if (r) {
622 dm_put_device(ti, p->path.dev);
623 goto bad;
624 }
625
626 return p;
627
628 bad:
629 free_pgpath(p);
630 return ERR_PTR(r);
631}
632
633static struct priority_group *parse_priority_group(struct dm_arg_set *as,
634 struct multipath *m)
635{
636 static struct dm_arg _args[] = {
637 {1, 1024, "invalid number of paths"},
638 {0, 1024, "invalid number of selector args"}
639 };
640
641 int r;
642 unsigned i, nr_selector_args, nr_args;
643 struct priority_group *pg;
644 struct dm_target *ti = m->ti;
645
646 if (as->argc < 2) {
647 as->argc = 0;
648 ti->error = "not enough priority group arguments";
649 return ERR_PTR(-EINVAL);
650 }
651
652 pg = alloc_priority_group();
653 if (!pg) {
654 ti->error = "couldn't allocate priority group";
655 return ERR_PTR(-ENOMEM);
656 }
657 pg->m = m;
658
659 r = parse_path_selector(as, pg, ti);
660 if (r)
661 goto bad;
662
663 /*
664 * read the paths
665 */
666 r = dm_read_arg(_args, as, &pg->nr_pgpaths, &ti->error);
667 if (r)
668 goto bad;
669
670 r = dm_read_arg(_args + 1, as, &nr_selector_args, &ti->error);
671 if (r)
672 goto bad;
673
674 nr_args = 1 + nr_selector_args;
675 for (i = 0; i < pg->nr_pgpaths; i++) {
676 struct pgpath *pgpath;
677 struct dm_arg_set path_args;
678
679 if (as->argc < nr_args) {
680 ti->error = "not enough path parameters";
681 r = -EINVAL;
682 goto bad;
683 }
684
685 path_args.argc = nr_args;
686 path_args.argv = as->argv;
687
688 pgpath = parse_path(&path_args, &pg->ps, ti);
689 if (IS_ERR(pgpath)) {
690 r = PTR_ERR(pgpath);
691 goto bad;
692 }
693
694 pgpath->pg = pg;
695 list_add_tail(&pgpath->list, &pg->pgpaths);
696 dm_consume_args(as, nr_args);
697 }
698
699 return pg;
700
701 bad:
702 free_priority_group(pg, ti);
703 return ERR_PTR(r);
704}
705
706static int parse_hw_handler(struct dm_arg_set *as, struct multipath *m)
707{
708 unsigned hw_argc;
709 int ret;
710 struct dm_target *ti = m->ti;
711
712 static struct dm_arg _args[] = {
713 {0, 1024, "invalid number of hardware handler args"},
714 };
715
716 if (dm_read_arg_group(_args, as, &hw_argc, &ti->error))
717 return -EINVAL;
718
719 if (!hw_argc)
720 return 0;
721
722 m->hw_handler_name = kstrdup(dm_shift_arg(as), GFP_KERNEL);
723 if (!try_then_request_module(scsi_dh_handler_exist(m->hw_handler_name),
724 "scsi_dh_%s", m->hw_handler_name)) {
725 ti->error = "unknown hardware handler type";
726 ret = -EINVAL;
727 goto fail;
728 }
729
730 if (hw_argc > 1) {
731 char *p;
732 int i, j, len = 4;
733
734 for (i = 0; i <= hw_argc - 2; i++)
735 len += strlen(as->argv[i]) + 1;
736 p = m->hw_handler_params = kzalloc(len, GFP_KERNEL);
737 if (!p) {
738 ti->error = "memory allocation failed";
739 ret = -ENOMEM;
740 goto fail;
741 }
742 j = sprintf(p, "%d", hw_argc - 1);
743 for (i = 0, p+=j+1; i <= hw_argc - 2; i++, p+=j+1)
744 j = sprintf(p, "%s", as->argv[i]);
745 }
746 dm_consume_args(as, hw_argc - 1);
747
748 return 0;
749fail:
750 kfree(m->hw_handler_name);
751 m->hw_handler_name = NULL;
752 return ret;
753}
754
755static int parse_features(struct dm_arg_set *as, struct multipath *m)
756{
757 int r;
758 unsigned argc;
759 struct dm_target *ti = m->ti;
760 const char *arg_name;
761
762 static struct dm_arg _args[] = {
763 {0, 5, "invalid number of feature args"},
764 {1, 50, "pg_init_retries must be between 1 and 50"},
765 {0, 60000, "pg_init_delay_msecs must be between 0 and 60000"},
766 };
767
768 r = dm_read_arg_group(_args, as, &argc, &ti->error);
769 if (r)
770 return -EINVAL;
771
772 if (!argc)
773 return 0;
774
775 do {
776 arg_name = dm_shift_arg(as);
777 argc--;
778
779 if (!strcasecmp(arg_name, "queue_if_no_path")) {
780 r = queue_if_no_path(m, 1, 0);
781 continue;
782 }
783
784 if (!strcasecmp(arg_name, "pg_init_retries") &&
785 (argc >= 1)) {
786 r = dm_read_arg(_args + 1, as, &m->pg_init_retries, &ti->error);
787 argc--;
788 continue;
789 }
790
791 if (!strcasecmp(arg_name, "pg_init_delay_msecs") &&
792 (argc >= 1)) {
793 r = dm_read_arg(_args + 2, as, &m->pg_init_delay_msecs, &ti->error);
794 argc--;
795 continue;
796 }
797
798 ti->error = "Unrecognised multipath feature request";
799 r = -EINVAL;
800 } while (argc && !r);
801
802 return r;
803}
804
805static int multipath_ctr(struct dm_target *ti, unsigned int argc,
806 char **argv)
807{
808 /* target arguments */
809 static struct dm_arg _args[] = {
810 {0, 1024, "invalid number of priority groups"},
811 {0, 1024, "invalid initial priority group number"},
812 };
813
814 int r;
815 struct multipath *m;
816 struct dm_arg_set as;
817 unsigned pg_count = 0;
818 unsigned next_pg_num;
819
820 as.argc = argc;
821 as.argv = argv;
822
823 m = alloc_multipath(ti);
824 if (!m) {
825 ti->error = "can't allocate multipath";
826 return -EINVAL;
827 }
828
829 r = parse_features(&as, m);
830 if (r)
831 goto bad;
832
833 r = parse_hw_handler(&as, m);
834 if (r)
835 goto bad;
836
837 r = dm_read_arg(_args, &as, &m->nr_priority_groups, &ti->error);
838 if (r)
839 goto bad;
840
841 r = dm_read_arg(_args + 1, &as, &next_pg_num, &ti->error);
842 if (r)
843 goto bad;
844
845 if ((!m->nr_priority_groups && next_pg_num) ||
846 (m->nr_priority_groups && !next_pg_num)) {
847 ti->error = "invalid initial priority group";
848 r = -EINVAL;
849 goto bad;
850 }
851
852 /* parse the priority groups */
853 while (as.argc) {
854 struct priority_group *pg;
855
856 pg = parse_priority_group(&as, m);
857 if (IS_ERR(pg)) {
858 r = PTR_ERR(pg);
859 goto bad;
860 }
861
862 m->nr_valid_paths += pg->nr_pgpaths;
863 list_add_tail(&pg->list, &m->priority_groups);
864 pg_count++;
865 pg->pg_num = pg_count;
866 if (!--next_pg_num)
867 m->next_pg = pg;
868 }
869
870 if (pg_count != m->nr_priority_groups) {
871 ti->error = "priority group count mismatch";
872 r = -EINVAL;
873 goto bad;
874 }
875
876 ti->num_flush_requests = 1;
877 ti->num_discard_requests = 1;
878
879 return 0;
880
881 bad:
882 free_multipath(m);
883 return r;
884}
885
886static void multipath_wait_for_pg_init_completion(struct multipath *m)
887{
888 DECLARE_WAITQUEUE(wait, current);
889 unsigned long flags;
890
891 add_wait_queue(&m->pg_init_wait, &wait);
892
893 while (1) {
894 set_current_state(TASK_UNINTERRUPTIBLE);
895
896 spin_lock_irqsave(&m->lock, flags);
897 if (!m->pg_init_in_progress) {
898 spin_unlock_irqrestore(&m->lock, flags);
899 break;
900 }
901 spin_unlock_irqrestore(&m->lock, flags);
902
903 io_schedule();
904 }
905 set_current_state(TASK_RUNNING);
906
907 remove_wait_queue(&m->pg_init_wait, &wait);
908}
909
910static void flush_multipath_work(struct multipath *m)
911{
912 flush_workqueue(kmpath_handlerd);
913 multipath_wait_for_pg_init_completion(m);
914 flush_workqueue(kmultipathd);
915 flush_work_sync(&m->trigger_event);
916}
917
918static void multipath_dtr(struct dm_target *ti)
919{
920 struct multipath *m = ti->private;
921
922 flush_multipath_work(m);
923 free_multipath(m);
924}
925
926/*
927 * Map cloned requests
928 */
929static int multipath_map(struct dm_target *ti, struct request *clone,
930 union map_info *map_context)
931{
932 int r;
933 struct multipath *m = (struct multipath *) ti->private;
934
935 if (set_mapinfo(m, map_context) < 0)
936 /* ENOMEM, requeue */
937 return DM_MAPIO_REQUEUE;
938
939 clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
940 r = map_io(m, clone, map_context, 0);
941 if (r < 0 || r == DM_MAPIO_REQUEUE)
942 clear_mapinfo(m, map_context);
943
944 return r;
945}
946
947/*
948 * Take a path out of use.
949 */
950static int fail_path(struct pgpath *pgpath)
951{
952 unsigned long flags;
953 struct multipath *m = pgpath->pg->m;
954
955 spin_lock_irqsave(&m->lock, flags);
956
957 if (!pgpath->is_active)
958 goto out;
959
960 DMWARN("Failing path %s.", pgpath->path.dev->name);
961
962 pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
963 pgpath->is_active = 0;
964 pgpath->fail_count++;
965
966 m->nr_valid_paths--;
967
968 if (pgpath == m->current_pgpath)
969 m->current_pgpath = NULL;
970
971 dm_path_uevent(DM_UEVENT_PATH_FAILED, m->ti,
972 pgpath->path.dev->name, m->nr_valid_paths);
973
974 schedule_work(&m->trigger_event);
975
976out:
977 spin_unlock_irqrestore(&m->lock, flags);
978
979 return 0;
980}
981
982/*
983 * Reinstate a previously-failed path
984 */
985static int reinstate_path(struct pgpath *pgpath)
986{
987 int r = 0;
988 unsigned long flags;
989 struct multipath *m = pgpath->pg->m;
990
991 spin_lock_irqsave(&m->lock, flags);
992
993 if (pgpath->is_active)
994 goto out;
995
996 if (!pgpath->pg->ps.type->reinstate_path) {
997 DMWARN("Reinstate path not supported by path selector %s",
998 pgpath->pg->ps.type->name);
999 r = -EINVAL;
1000 goto out;
1001 }
1002
1003 r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
1004 if (r)
1005 goto out;
1006
1007 pgpath->is_active = 1;
1008
1009 if (!m->nr_valid_paths++ && m->queue_size) {
1010 m->current_pgpath = NULL;
1011 queue_work(kmultipathd, &m->process_queued_ios);
1012 } else if (m->hw_handler_name && (m->current_pg == pgpath->pg)) {
1013 if (queue_work(kmpath_handlerd, &pgpath->activate_path.work))
1014 m->pg_init_in_progress++;
1015 }
1016
1017 dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti,
1018 pgpath->path.dev->name, m->nr_valid_paths);
1019
1020 schedule_work(&m->trigger_event);
1021
1022out:
1023 spin_unlock_irqrestore(&m->lock, flags);
1024
1025 return r;
1026}
1027
1028/*
1029 * Fail or reinstate all paths that match the provided struct dm_dev.
1030 */
1031static int action_dev(struct multipath *m, struct dm_dev *dev,
1032 action_fn action)
1033{
1034 int r = -EINVAL;
1035 struct pgpath *pgpath;
1036 struct priority_group *pg;
1037
1038 list_for_each_entry(pg, &m->priority_groups, list) {
1039 list_for_each_entry(pgpath, &pg->pgpaths, list) {
1040 if (pgpath->path.dev == dev)
1041 r = action(pgpath);
1042 }
1043 }
1044
1045 return r;
1046}
1047
1048/*
1049 * Temporarily try to avoid having to use the specified PG
1050 */
1051static void bypass_pg(struct multipath *m, struct priority_group *pg,
1052 int bypassed)
1053{
1054 unsigned long flags;
1055
1056 spin_lock_irqsave(&m->lock, flags);
1057
1058 pg->bypassed = bypassed;
1059 m->current_pgpath = NULL;
1060 m->current_pg = NULL;
1061
1062 spin_unlock_irqrestore(&m->lock, flags);
1063
1064 schedule_work(&m->trigger_event);
1065}
1066
1067/*
1068 * Switch to using the specified PG from the next I/O that gets mapped
1069 */
1070static int switch_pg_num(struct multipath *m, const char *pgstr)
1071{
1072 struct priority_group *pg;
1073 unsigned pgnum;
1074 unsigned long flags;
1075 char dummy;
1076
1077 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1078 (pgnum > m->nr_priority_groups)) {
1079 DMWARN("invalid PG number supplied to switch_pg_num");
1080 return -EINVAL;
1081 }
1082
1083 spin_lock_irqsave(&m->lock, flags);
1084 list_for_each_entry(pg, &m->priority_groups, list) {
1085 pg->bypassed = 0;
1086 if (--pgnum)
1087 continue;
1088
1089 m->current_pgpath = NULL;
1090 m->current_pg = NULL;
1091 m->next_pg = pg;
1092 }
1093 spin_unlock_irqrestore(&m->lock, flags);
1094
1095 schedule_work(&m->trigger_event);
1096 return 0;
1097}
1098
1099/*
1100 * Set/clear bypassed status of a PG.
1101 * PGs are numbered upwards from 1 in the order they were declared.
1102 */
1103static int bypass_pg_num(struct multipath *m, const char *pgstr, int bypassed)
1104{
1105 struct priority_group *pg;
1106 unsigned pgnum;
1107 char dummy;
1108
1109 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1110 (pgnum > m->nr_priority_groups)) {
1111 DMWARN("invalid PG number supplied to bypass_pg");
1112 return -EINVAL;
1113 }
1114
1115 list_for_each_entry(pg, &m->priority_groups, list) {
1116 if (!--pgnum)
1117 break;
1118 }
1119
1120 bypass_pg(m, pg, bypassed);
1121 return 0;
1122}
1123
1124/*
1125 * Should we retry pg_init immediately?
1126 */
1127static int pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath)
1128{
1129 unsigned long flags;
1130 int limit_reached = 0;
1131
1132 spin_lock_irqsave(&m->lock, flags);
1133
1134 if (m->pg_init_count <= m->pg_init_retries)
1135 m->pg_init_required = 1;
1136 else
1137 limit_reached = 1;
1138
1139 spin_unlock_irqrestore(&m->lock, flags);
1140
1141 return limit_reached;
1142}
1143
1144static void pg_init_done(void *data, int errors)
1145{
1146 struct pgpath *pgpath = data;
1147 struct priority_group *pg = pgpath->pg;
1148 struct multipath *m = pg->m;
1149 unsigned long flags;
1150 unsigned delay_retry = 0;
1151
1152 /* device or driver problems */
1153 switch (errors) {
1154 case SCSI_DH_OK:
1155 break;
1156 case SCSI_DH_NOSYS:
1157 if (!m->hw_handler_name) {
1158 errors = 0;
1159 break;
1160 }
1161 DMERR("Could not failover the device: Handler scsi_dh_%s "
1162 "Error %d.", m->hw_handler_name, errors);
1163 /*
1164 * Fail path for now, so we do not ping pong
1165 */
1166 fail_path(pgpath);
1167 break;
1168 case SCSI_DH_DEV_TEMP_BUSY:
1169 /*
1170 * Probably doing something like FW upgrade on the
1171 * controller so try the other pg.
1172 */
1173 bypass_pg(m, pg, 1);
1174 break;
1175 case SCSI_DH_RETRY:
1176 /* Wait before retrying. */
1177 delay_retry = 1;
1178 case SCSI_DH_IMM_RETRY:
1179 case SCSI_DH_RES_TEMP_UNAVAIL:
1180 if (pg_init_limit_reached(m, pgpath))
1181 fail_path(pgpath);
1182 errors = 0;
1183 break;
1184 default:
1185 /*
1186 * We probably do not want to fail the path for a device
1187 * error, but this is what the old dm did. In future
1188 * patches we can do more advanced handling.
1189 */
1190 fail_path(pgpath);
1191 }
1192
1193 spin_lock_irqsave(&m->lock, flags);
1194 if (errors) {
1195 if (pgpath == m->current_pgpath) {
1196 DMERR("Could not failover device. Error %d.", errors);
1197 m->current_pgpath = NULL;
1198 m->current_pg = NULL;
1199 }
1200 } else if (!m->pg_init_required)
1201 pg->bypassed = 0;
1202
1203 if (--m->pg_init_in_progress)
1204 /* Activations of other paths are still on going */
1205 goto out;
1206
1207 if (!m->pg_init_required)
1208 m->queue_io = 0;
1209
1210 m->pg_init_delay_retry = delay_retry;
1211 queue_work(kmultipathd, &m->process_queued_ios);
1212
1213 /*
1214 * Wake up any thread waiting to suspend.
1215 */
1216 wake_up(&m->pg_init_wait);
1217
1218out:
1219 spin_unlock_irqrestore(&m->lock, flags);
1220}
1221
1222static void activate_path(struct work_struct *work)
1223{
1224 struct pgpath *pgpath =
1225 container_of(work, struct pgpath, activate_path.work);
1226
1227 scsi_dh_activate(bdev_get_queue(pgpath->path.dev->bdev),
1228 pg_init_done, pgpath);
1229}
1230
1231/*
1232 * end_io handling
1233 */
1234static int do_end_io(struct multipath *m, struct request *clone,
1235 int error, struct dm_mpath_io *mpio)
1236{
1237 /*
1238 * We don't queue any clone request inside the multipath target
1239 * during end I/O handling, since those clone requests don't have
1240 * bio clones. If we queue them inside the multipath target,
1241 * we need to make bio clones, that requires memory allocation.
1242 * (See drivers/md/dm.c:end_clone_bio() about why the clone requests
1243 * don't have bio clones.)
1244 * Instead of queueing the clone request here, we queue the original
1245 * request into dm core, which will remake a clone request and
1246 * clone bios for it and resubmit it later.
1247 */
1248 int r = DM_ENDIO_REQUEUE;
1249 unsigned long flags;
1250
1251 if (!error && !clone->errors)
1252 return 0; /* I/O complete */
1253
1254 if (error == -EOPNOTSUPP || error == -EREMOTEIO || error == -EILSEQ)
1255 return error;
1256
1257 if (mpio->pgpath)
1258 fail_path(mpio->pgpath);
1259
1260 spin_lock_irqsave(&m->lock, flags);
1261 if (!m->nr_valid_paths) {
1262 if (!m->queue_if_no_path) {
1263 if (!__must_push_back(m))
1264 r = -EIO;
1265 } else {
1266 if (error == -EBADE)
1267 r = error;
1268 }
1269 }
1270 spin_unlock_irqrestore(&m->lock, flags);
1271
1272 return r;
1273}
1274
1275static int multipath_end_io(struct dm_target *ti, struct request *clone,
1276 int error, union map_info *map_context)
1277{
1278 struct multipath *m = ti->private;
1279 struct dm_mpath_io *mpio = map_context->ptr;
1280 struct pgpath *pgpath = mpio->pgpath;
1281 struct path_selector *ps;
1282 int r;
1283
1284 BUG_ON(!mpio);
1285
1286 r = do_end_io(m, clone, error, mpio);
1287 if (pgpath) {
1288 ps = &pgpath->pg->ps;
1289 if (ps->type->end_io)
1290 ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
1291 }
1292 clear_mapinfo(m, map_context);
1293
1294 return r;
1295}
1296
1297/*
1298 * Suspend can't complete until all the I/O is processed so if
1299 * the last path fails we must error any remaining I/O.
1300 * Note that if the freeze_bdev fails while suspending, the
1301 * queue_if_no_path state is lost - userspace should reset it.
1302 */
1303static void multipath_presuspend(struct dm_target *ti)
1304{
1305 struct multipath *m = (struct multipath *) ti->private;
1306
1307 queue_if_no_path(m, 0, 1);
1308}
1309
1310static void multipath_postsuspend(struct dm_target *ti)
1311{
1312 struct multipath *m = ti->private;
1313
1314 mutex_lock(&m->work_mutex);
1315 flush_multipath_work(m);
1316 mutex_unlock(&m->work_mutex);
1317}
1318
1319/*
1320 * Restore the queue_if_no_path setting.
1321 */
1322static void multipath_resume(struct dm_target *ti)
1323{
1324 struct multipath *m = (struct multipath *) ti->private;
1325 unsigned long flags;
1326
1327 spin_lock_irqsave(&m->lock, flags);
1328 m->queue_if_no_path = m->saved_queue_if_no_path;
1329 spin_unlock_irqrestore(&m->lock, flags);
1330}
1331
1332/*
1333 * Info output has the following format:
1334 * num_multipath_feature_args [multipath_feature_args]*
1335 * num_handler_status_args [handler_status_args]*
1336 * num_groups init_group_number
1337 * [A|D|E num_ps_status_args [ps_status_args]*
1338 * num_paths num_selector_args
1339 * [path_dev A|F fail_count [selector_args]* ]+ ]+
1340 *
1341 * Table output has the following format (identical to the constructor string):
1342 * num_feature_args [features_args]*
1343 * num_handler_args hw_handler [hw_handler_args]*
1344 * num_groups init_group_number
1345 * [priority selector-name num_ps_args [ps_args]*
1346 * num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
1347 */
1348static int multipath_status(struct dm_target *ti, status_type_t type,
1349 char *result, unsigned int maxlen)
1350{
1351 int sz = 0;
1352 unsigned long flags;
1353 struct multipath *m = (struct multipath *) ti->private;
1354 struct priority_group *pg;
1355 struct pgpath *p;
1356 unsigned pg_num;
1357 char state;
1358
1359 spin_lock_irqsave(&m->lock, flags);
1360
1361 /* Features */
1362 if (type == STATUSTYPE_INFO)
1363 DMEMIT("2 %u %u ", m->queue_size, m->pg_init_count);
1364 else {
1365 DMEMIT("%u ", m->queue_if_no_path +
1366 (m->pg_init_retries > 0) * 2 +
1367 (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT) * 2);
1368 if (m->queue_if_no_path)
1369 DMEMIT("queue_if_no_path ");
1370 if (m->pg_init_retries)
1371 DMEMIT("pg_init_retries %u ", m->pg_init_retries);
1372 if (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT)
1373 DMEMIT("pg_init_delay_msecs %u ", m->pg_init_delay_msecs);
1374 }
1375
1376 if (!m->hw_handler_name || type == STATUSTYPE_INFO)
1377 DMEMIT("0 ");
1378 else
1379 DMEMIT("1 %s ", m->hw_handler_name);
1380
1381 DMEMIT("%u ", m->nr_priority_groups);
1382
1383 if (m->next_pg)
1384 pg_num = m->next_pg->pg_num;
1385 else if (m->current_pg)
1386 pg_num = m->current_pg->pg_num;
1387 else
1388 pg_num = (m->nr_priority_groups ? 1 : 0);
1389
1390 DMEMIT("%u ", pg_num);
1391
1392 switch (type) {
1393 case STATUSTYPE_INFO:
1394 list_for_each_entry(pg, &m->priority_groups, list) {
1395 if (pg->bypassed)
1396 state = 'D'; /* Disabled */
1397 else if (pg == m->current_pg)
1398 state = 'A'; /* Currently Active */
1399 else
1400 state = 'E'; /* Enabled */
1401
1402 DMEMIT("%c ", state);
1403
1404 if (pg->ps.type->status)
1405 sz += pg->ps.type->status(&pg->ps, NULL, type,
1406 result + sz,
1407 maxlen - sz);
1408 else
1409 DMEMIT("0 ");
1410
1411 DMEMIT("%u %u ", pg->nr_pgpaths,
1412 pg->ps.type->info_args);
1413
1414 list_for_each_entry(p, &pg->pgpaths, list) {
1415 DMEMIT("%s %s %u ", p->path.dev->name,
1416 p->is_active ? "A" : "F",
1417 p->fail_count);
1418 if (pg->ps.type->status)
1419 sz += pg->ps.type->status(&pg->ps,
1420 &p->path, type, result + sz,
1421 maxlen - sz);
1422 }
1423 }
1424 break;
1425
1426 case STATUSTYPE_TABLE:
1427 list_for_each_entry(pg, &m->priority_groups, list) {
1428 DMEMIT("%s ", pg->ps.type->name);
1429
1430 if (pg->ps.type->status)
1431 sz += pg->ps.type->status(&pg->ps, NULL, type,
1432 result + sz,
1433 maxlen - sz);
1434 else
1435 DMEMIT("0 ");
1436
1437 DMEMIT("%u %u ", pg->nr_pgpaths,
1438 pg->ps.type->table_args);
1439
1440 list_for_each_entry(p, &pg->pgpaths, list) {
1441 DMEMIT("%s ", p->path.dev->name);
1442 if (pg->ps.type->status)
1443 sz += pg->ps.type->status(&pg->ps,
1444 &p->path, type, result + sz,
1445 maxlen - sz);
1446 }
1447 }
1448 break;
1449 }
1450
1451 spin_unlock_irqrestore(&m->lock, flags);
1452
1453 return 0;
1454}
1455
1456static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
1457{
1458 int r = -EINVAL;
1459 struct dm_dev *dev;
1460 struct multipath *m = (struct multipath *) ti->private;
1461 action_fn action;
1462
1463 mutex_lock(&m->work_mutex);
1464
1465 if (dm_suspended(ti)) {
1466 r = -EBUSY;
1467 goto out;
1468 }
1469
1470 if (argc == 1) {
1471 if (!strcasecmp(argv[0], "queue_if_no_path")) {
1472 r = queue_if_no_path(m, 1, 0);
1473 goto out;
1474 } else if (!strcasecmp(argv[0], "fail_if_no_path")) {
1475 r = queue_if_no_path(m, 0, 0);
1476 goto out;
1477 }
1478 }
1479
1480 if (argc != 2) {
1481 DMWARN("Unrecognised multipath message received.");
1482 goto out;
1483 }
1484
1485 if (!strcasecmp(argv[0], "disable_group")) {
1486 r = bypass_pg_num(m, argv[1], 1);
1487 goto out;
1488 } else if (!strcasecmp(argv[0], "enable_group")) {
1489 r = bypass_pg_num(m, argv[1], 0);
1490 goto out;
1491 } else if (!strcasecmp(argv[0], "switch_group")) {
1492 r = switch_pg_num(m, argv[1]);
1493 goto out;
1494 } else if (!strcasecmp(argv[0], "reinstate_path"))
1495 action = reinstate_path;
1496 else if (!strcasecmp(argv[0], "fail_path"))
1497 action = fail_path;
1498 else {
1499 DMWARN("Unrecognised multipath message received.");
1500 goto out;
1501 }
1502
1503 r = dm_get_device(ti, argv[1], dm_table_get_mode(ti->table), &dev);
1504 if (r) {
1505 DMWARN("message: error getting device %s",
1506 argv[1]);
1507 goto out;
1508 }
1509
1510 r = action_dev(m, dev, action);
1511
1512 dm_put_device(ti, dev);
1513
1514out:
1515 mutex_unlock(&m->work_mutex);
1516 return r;
1517}
1518
1519static int multipath_ioctl(struct dm_target *ti, unsigned int cmd,
1520 unsigned long arg)
1521{
1522 struct multipath *m = ti->private;
1523 struct pgpath *pgpath;
1524 struct block_device *bdev;
1525 fmode_t mode;
1526 unsigned long flags;
1527 int r;
1528
1529again:
1530 bdev = NULL;
1531 mode = 0;
1532 r = 0;
1533
1534 spin_lock_irqsave(&m->lock, flags);
1535
1536 if (!m->current_pgpath)
1537 __choose_pgpath(m, 0);
1538
1539 pgpath = m->current_pgpath;
1540
1541 if (pgpath) {
1542 bdev = pgpath->path.dev->bdev;
1543 mode = pgpath->path.dev->mode;
1544 }
1545
1546 if ((pgpath && m->queue_io) || (!pgpath && m->queue_if_no_path))
1547 r = -EAGAIN;
1548 else if (!bdev)
1549 r = -EIO;
1550
1551 spin_unlock_irqrestore(&m->lock, flags);
1552
1553 /*
1554 * Only pass ioctls through if the device sizes match exactly.
1555 */
1556 if (!r && ti->len != i_size_read(bdev->bd_inode) >> SECTOR_SHIFT)
1557 r = scsi_verify_blk_ioctl(NULL, cmd);
1558
1559 if (r == -EAGAIN && !fatal_signal_pending(current)) {
1560 queue_work(kmultipathd, &m->process_queued_ios);
1561 msleep(10);
1562 goto again;
1563 }
1564
1565 return r ? : __blkdev_driver_ioctl(bdev, mode, cmd, arg);
1566}
1567
1568static int multipath_iterate_devices(struct dm_target *ti,
1569 iterate_devices_callout_fn fn, void *data)
1570{
1571 struct multipath *m = ti->private;
1572 struct priority_group *pg;
1573 struct pgpath *p;
1574 int ret = 0;
1575
1576 list_for_each_entry(pg, &m->priority_groups, list) {
1577 list_for_each_entry(p, &pg->pgpaths, list) {
1578 ret = fn(ti, p->path.dev, ti->begin, ti->len, data);
1579 if (ret)
1580 goto out;
1581 }
1582 }
1583
1584out:
1585 return ret;
1586}
1587
1588static int __pgpath_busy(struct pgpath *pgpath)
1589{
1590 struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
1591
1592 return dm_underlying_device_busy(q);
1593}
1594
1595/*
1596 * We return "busy", only when we can map I/Os but underlying devices
1597 * are busy (so even if we map I/Os now, the I/Os will wait on
1598 * the underlying queue).
1599 * In other words, if we want to kill I/Os or queue them inside us
1600 * due to map unavailability, we don't return "busy". Otherwise,
1601 * dm core won't give us the I/Os and we can't do what we want.
1602 */
1603static int multipath_busy(struct dm_target *ti)
1604{
1605 int busy = 0, has_active = 0;
1606 struct multipath *m = ti->private;
1607 struct priority_group *pg;
1608 struct pgpath *pgpath;
1609 unsigned long flags;
1610
1611 spin_lock_irqsave(&m->lock, flags);
1612
1613 /* Guess which priority_group will be used at next mapping time */
1614 if (unlikely(!m->current_pgpath && m->next_pg))
1615 pg = m->next_pg;
1616 else if (likely(m->current_pg))
1617 pg = m->current_pg;
1618 else
1619 /*
1620 * We don't know which pg will be used at next mapping time.
1621 * We don't call __choose_pgpath() here to avoid to trigger
1622 * pg_init just by busy checking.
1623 * So we don't know whether underlying devices we will be using
1624 * at next mapping time are busy or not. Just try mapping.
1625 */
1626 goto out;
1627
1628 /*
1629 * If there is one non-busy active path at least, the path selector
1630 * will be able to select it. So we consider such a pg as not busy.
1631 */
1632 busy = 1;
1633 list_for_each_entry(pgpath, &pg->pgpaths, list)
1634 if (pgpath->is_active) {
1635 has_active = 1;
1636
1637 if (!__pgpath_busy(pgpath)) {
1638 busy = 0;
1639 break;
1640 }
1641 }
1642
1643 if (!has_active)
1644 /*
1645 * No active path in this pg, so this pg won't be used and
1646 * the current_pg will be changed at next mapping time.
1647 * We need to try mapping to determine it.
1648 */
1649 busy = 0;
1650
1651out:
1652 spin_unlock_irqrestore(&m->lock, flags);
1653
1654 return busy;
1655}
1656
1657/*-----------------------------------------------------------------
1658 * Module setup
1659 *---------------------------------------------------------------*/
1660static struct target_type multipath_target = {
1661 .name = "multipath",
1662 .version = {1, 4, 0},
1663 .module = THIS_MODULE,
1664 .ctr = multipath_ctr,
1665 .dtr = multipath_dtr,
1666 .map_rq = multipath_map,
1667 .rq_end_io = multipath_end_io,
1668 .presuspend = multipath_presuspend,
1669 .postsuspend = multipath_postsuspend,
1670 .resume = multipath_resume,
1671 .status = multipath_status,
1672 .message = multipath_message,
1673 .ioctl = multipath_ioctl,
1674 .iterate_devices = multipath_iterate_devices,
1675 .busy = multipath_busy,
1676};
1677
1678static int __init dm_multipath_init(void)
1679{
1680 int r;
1681
1682 /* allocate a slab for the dm_ios */
1683 _mpio_cache = KMEM_CACHE(dm_mpath_io, 0);
1684 if (!_mpio_cache)
1685 return -ENOMEM;
1686
1687 r = dm_register_target(&multipath_target);
1688 if (r < 0) {
1689 DMERR("register failed %d", r);
1690 kmem_cache_destroy(_mpio_cache);
1691 return -EINVAL;
1692 }
1693
1694 kmultipathd = alloc_workqueue("kmpathd", WQ_MEM_RECLAIM, 0);
1695 if (!kmultipathd) {
1696 DMERR("failed to create workqueue kmpathd");
1697 dm_unregister_target(&multipath_target);
1698 kmem_cache_destroy(_mpio_cache);
1699 return -ENOMEM;
1700 }
1701
1702 /*
1703 * A separate workqueue is used to handle the device handlers
1704 * to avoid overloading existing workqueue. Overloading the
1705 * old workqueue would also create a bottleneck in the
1706 * path of the storage hardware device activation.
1707 */
1708 kmpath_handlerd = alloc_ordered_workqueue("kmpath_handlerd",
1709 WQ_MEM_RECLAIM);
1710 if (!kmpath_handlerd) {
1711 DMERR("failed to create workqueue kmpath_handlerd");
1712 destroy_workqueue(kmultipathd);
1713 dm_unregister_target(&multipath_target);
1714 kmem_cache_destroy(_mpio_cache);
1715 return -ENOMEM;
1716 }
1717
1718 DMINFO("version %u.%u.%u loaded",
1719 multipath_target.version[0], multipath_target.version[1],
1720 multipath_target.version[2]);
1721
1722 return r;
1723}
1724
1725static void __exit dm_multipath_exit(void)
1726{
1727 destroy_workqueue(kmpath_handlerd);
1728 destroy_workqueue(kmultipathd);
1729
1730 dm_unregister_target(&multipath_target);
1731 kmem_cache_destroy(_mpio_cache);
1732}
1733
1734module_init(dm_multipath_init);
1735module_exit(dm_multipath_exit);
1736
1737MODULE_DESCRIPTION(DM_NAME " multipath target");
1738MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
1739MODULE_LICENSE("GPL");