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