[PATCH] 8139too deadlock fix
[linux-2.6/openmoko-kernel/knife-kernel.git] / drivers / md / dm-mpath.c
blob217615b3322351f4d653b355d1b7290f36248631
1 /*
2 * Copyright (C) 2003 Sistina Software Limited.
3 * Copyright (C) 2004-2005 Red Hat, Inc. All rights reserved.
5 * This file is released under the GPL.
6 */
8 #include "dm.h"
9 #include "dm-path-selector.h"
10 #include "dm-hw-handler.h"
11 #include "dm-bio-list.h"
12 #include "dm-bio-record.h"
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 <asm/atomic.h>
24 #define DM_MSG_PREFIX "multipath"
25 #define MESG_STR(x) x, sizeof(x)
27 /* Path properties */
28 struct pgpath {
29 struct list_head list;
31 struct priority_group *pg; /* Owning PG */
32 unsigned fail_count; /* Cumulative failure count */
34 struct path path;
37 #define path_to_pgpath(__pgp) container_of((__pgp), struct pgpath, path)
40 * Paths are grouped into Priority Groups and numbered from 1 upwards.
41 * Each has a path selector which controls which path gets used.
43 struct priority_group {
44 struct list_head list;
46 struct multipath *m; /* Owning multipath instance */
47 struct path_selector ps;
49 unsigned pg_num; /* Reference number */
50 unsigned bypassed; /* Temporarily bypass this PG? */
52 unsigned nr_pgpaths; /* Number of paths in PG */
53 struct list_head pgpaths;
56 /* Multipath context */
57 struct multipath {
58 struct list_head list;
59 struct dm_target *ti;
61 spinlock_t lock;
63 struct hw_handler hw_handler;
64 unsigned nr_priority_groups;
65 struct list_head priority_groups;
66 unsigned pg_init_required; /* pg_init needs calling? */
67 unsigned pg_init_in_progress; /* Only one pg_init allowed at once */
69 unsigned nr_valid_paths; /* Total number of usable paths */
70 struct pgpath *current_pgpath;
71 struct priority_group *current_pg;
72 struct priority_group *next_pg; /* Switch to this PG if set */
73 unsigned repeat_count; /* I/Os left before calling PS again */
75 unsigned queue_io; /* Must we queue all I/O? */
76 unsigned queue_if_no_path; /* Queue I/O if last path fails? */
77 unsigned saved_queue_if_no_path;/* Saved state during suspension */
79 struct work_struct process_queued_ios;
80 struct bio_list queued_ios;
81 unsigned queue_size;
83 struct work_struct trigger_event;
86 * We must use a mempool of mpath_io structs so that we
87 * can resubmit bios on error.
89 mempool_t *mpio_pool;
93 * Context information attached to each bio we process.
95 struct mpath_io {
96 struct pgpath *pgpath;
97 struct dm_bio_details details;
100 typedef int (*action_fn) (struct pgpath *pgpath);
102 #define MIN_IOS 256 /* Mempool size */
104 static kmem_cache_t *_mpio_cache;
106 struct workqueue_struct *kmultipathd;
107 static void process_queued_ios(void *data);
108 static void trigger_event(void *data);
111 /*-----------------------------------------------
112 * Allocation routines
113 *-----------------------------------------------*/
115 static struct pgpath *alloc_pgpath(void)
117 struct pgpath *pgpath = kmalloc(sizeof(*pgpath), GFP_KERNEL);
119 if (pgpath) {
120 memset(pgpath, 0, sizeof(*pgpath));
121 pgpath->path.is_active = 1;
124 return pgpath;
127 static inline void free_pgpath(struct pgpath *pgpath)
129 kfree(pgpath);
132 static struct priority_group *alloc_priority_group(void)
134 struct priority_group *pg;
136 pg = kmalloc(sizeof(*pg), GFP_KERNEL);
137 if (!pg)
138 return NULL;
140 memset(pg, 0, sizeof(*pg));
141 INIT_LIST_HEAD(&pg->pgpaths);
143 return pg;
146 static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti)
148 struct pgpath *pgpath, *tmp;
150 list_for_each_entry_safe(pgpath, tmp, pgpaths, list) {
151 list_del(&pgpath->list);
152 dm_put_device(ti, pgpath->path.dev);
153 free_pgpath(pgpath);
157 static void free_priority_group(struct priority_group *pg,
158 struct dm_target *ti)
160 struct path_selector *ps = &pg->ps;
162 if (ps->type) {
163 ps->type->destroy(ps);
164 dm_put_path_selector(ps->type);
167 free_pgpaths(&pg->pgpaths, ti);
168 kfree(pg);
171 static struct multipath *alloc_multipath(void)
173 struct multipath *m;
175 m = kmalloc(sizeof(*m), GFP_KERNEL);
176 if (m) {
177 memset(m, 0, sizeof(*m));
178 INIT_LIST_HEAD(&m->priority_groups);
179 spin_lock_init(&m->lock);
180 m->queue_io = 1;
181 INIT_WORK(&m->process_queued_ios, process_queued_ios, m);
182 INIT_WORK(&m->trigger_event, trigger_event, m);
183 m->mpio_pool = mempool_create_slab_pool(MIN_IOS, _mpio_cache);
184 if (!m->mpio_pool) {
185 kfree(m);
186 return NULL;
190 return m;
193 static void free_multipath(struct multipath *m)
195 struct priority_group *pg, *tmp;
196 struct hw_handler *hwh = &m->hw_handler;
198 list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) {
199 list_del(&pg->list);
200 free_priority_group(pg, m->ti);
203 if (hwh->type) {
204 hwh->type->destroy(hwh);
205 dm_put_hw_handler(hwh->type);
208 mempool_destroy(m->mpio_pool);
209 kfree(m);
213 /*-----------------------------------------------
214 * Path selection
215 *-----------------------------------------------*/
217 static void __switch_pg(struct multipath *m, struct pgpath *pgpath)
219 struct hw_handler *hwh = &m->hw_handler;
221 m->current_pg = pgpath->pg;
223 /* Must we initialise the PG first, and queue I/O till it's ready? */
224 if (hwh->type && hwh->type->pg_init) {
225 m->pg_init_required = 1;
226 m->queue_io = 1;
227 } else {
228 m->pg_init_required = 0;
229 m->queue_io = 0;
233 static int __choose_path_in_pg(struct multipath *m, struct priority_group *pg)
235 struct path *path;
237 path = pg->ps.type->select_path(&pg->ps, &m->repeat_count);
238 if (!path)
239 return -ENXIO;
241 m->current_pgpath = path_to_pgpath(path);
243 if (m->current_pg != pg)
244 __switch_pg(m, m->current_pgpath);
246 return 0;
249 static void __choose_pgpath(struct multipath *m)
251 struct priority_group *pg;
252 unsigned bypassed = 1;
254 if (!m->nr_valid_paths)
255 goto failed;
257 /* Were we instructed to switch PG? */
258 if (m->next_pg) {
259 pg = m->next_pg;
260 m->next_pg = NULL;
261 if (!__choose_path_in_pg(m, pg))
262 return;
265 /* Don't change PG until it has no remaining paths */
266 if (m->current_pg && !__choose_path_in_pg(m, m->current_pg))
267 return;
270 * Loop through priority groups until we find a valid path.
271 * First time we skip PGs marked 'bypassed'.
272 * Second time we only try the ones we skipped.
274 do {
275 list_for_each_entry(pg, &m->priority_groups, list) {
276 if (pg->bypassed == bypassed)
277 continue;
278 if (!__choose_path_in_pg(m, pg))
279 return;
281 } while (bypassed--);
283 failed:
284 m->current_pgpath = NULL;
285 m->current_pg = NULL;
288 static int map_io(struct multipath *m, struct bio *bio, struct mpath_io *mpio,
289 unsigned was_queued)
291 int r = 1;
292 unsigned long flags;
293 struct pgpath *pgpath;
295 spin_lock_irqsave(&m->lock, flags);
297 /* Do we need to select a new pgpath? */
298 if (!m->current_pgpath ||
299 (!m->queue_io && (m->repeat_count && --m->repeat_count == 0)))
300 __choose_pgpath(m);
302 pgpath = m->current_pgpath;
304 if (was_queued)
305 m->queue_size--;
307 if ((pgpath && m->queue_io) ||
308 (!pgpath && m->queue_if_no_path)) {
309 /* Queue for the daemon to resubmit */
310 bio_list_add(&m->queued_ios, bio);
311 m->queue_size++;
312 if ((m->pg_init_required && !m->pg_init_in_progress) ||
313 !m->queue_io)
314 queue_work(kmultipathd, &m->process_queued_ios);
315 pgpath = NULL;
316 r = 0;
317 } else if (!pgpath)
318 r = -EIO; /* Failed */
319 else
320 bio->bi_bdev = pgpath->path.dev->bdev;
322 mpio->pgpath = pgpath;
324 spin_unlock_irqrestore(&m->lock, flags);
326 return r;
330 * If we run out of usable paths, should we queue I/O or error it?
332 static int queue_if_no_path(struct multipath *m, unsigned queue_if_no_path,
333 unsigned save_old_value)
335 unsigned long flags;
337 spin_lock_irqsave(&m->lock, flags);
339 if (save_old_value)
340 m->saved_queue_if_no_path = m->queue_if_no_path;
341 else
342 m->saved_queue_if_no_path = queue_if_no_path;
343 m->queue_if_no_path = queue_if_no_path;
344 if (!m->queue_if_no_path && m->queue_size)
345 queue_work(kmultipathd, &m->process_queued_ios);
347 spin_unlock_irqrestore(&m->lock, flags);
349 return 0;
352 /*-----------------------------------------------------------------
353 * The multipath daemon is responsible for resubmitting queued ios.
354 *---------------------------------------------------------------*/
356 static void dispatch_queued_ios(struct multipath *m)
358 int r;
359 unsigned long flags;
360 struct bio *bio = NULL, *next;
361 struct mpath_io *mpio;
362 union map_info *info;
364 spin_lock_irqsave(&m->lock, flags);
365 bio = bio_list_get(&m->queued_ios);
366 spin_unlock_irqrestore(&m->lock, flags);
368 while (bio) {
369 next = bio->bi_next;
370 bio->bi_next = NULL;
372 info = dm_get_mapinfo(bio);
373 mpio = info->ptr;
375 r = map_io(m, bio, mpio, 1);
376 if (r < 0)
377 bio_endio(bio, bio->bi_size, r);
378 else if (r == 1)
379 generic_make_request(bio);
381 bio = next;
385 static void process_queued_ios(void *data)
387 struct multipath *m = (struct multipath *) data;
388 struct hw_handler *hwh = &m->hw_handler;
389 struct pgpath *pgpath = NULL;
390 unsigned init_required = 0, must_queue = 1;
391 unsigned long flags;
393 spin_lock_irqsave(&m->lock, flags);
395 if (!m->queue_size)
396 goto out;
398 if (!m->current_pgpath)
399 __choose_pgpath(m);
401 pgpath = m->current_pgpath;
403 if ((pgpath && !m->queue_io) ||
404 (!pgpath && !m->queue_if_no_path))
405 must_queue = 0;
407 if (m->pg_init_required && !m->pg_init_in_progress) {
408 m->pg_init_required = 0;
409 m->pg_init_in_progress = 1;
410 init_required = 1;
413 out:
414 spin_unlock_irqrestore(&m->lock, flags);
416 if (init_required)
417 hwh->type->pg_init(hwh, pgpath->pg->bypassed, &pgpath->path);
419 if (!must_queue)
420 dispatch_queued_ios(m);
424 * An event is triggered whenever a path is taken out of use.
425 * Includes path failure and PG bypass.
427 static void trigger_event(void *data)
429 struct multipath *m = (struct multipath *) data;
431 dm_table_event(m->ti->table);
434 /*-----------------------------------------------------------------
435 * Constructor/argument parsing:
436 * <#multipath feature args> [<arg>]*
437 * <#hw_handler args> [hw_handler [<arg>]*]
438 * <#priority groups>
439 * <initial priority group>
440 * [<selector> <#selector args> [<arg>]*
441 * <#paths> <#per-path selector args>
442 * [<path> [<arg>]* ]+ ]+
443 *---------------------------------------------------------------*/
444 struct param {
445 unsigned min;
446 unsigned max;
447 char *error;
450 static int read_param(struct param *param, char *str, unsigned *v, char **error)
452 if (!str ||
453 (sscanf(str, "%u", v) != 1) ||
454 (*v < param->min) ||
455 (*v > param->max)) {
456 *error = param->error;
457 return -EINVAL;
460 return 0;
463 struct arg_set {
464 unsigned argc;
465 char **argv;
468 static char *shift(struct arg_set *as)
470 char *r;
472 if (as->argc) {
473 as->argc--;
474 r = *as->argv;
475 as->argv++;
476 return r;
479 return NULL;
482 static void consume(struct arg_set *as, unsigned n)
484 BUG_ON (as->argc < n);
485 as->argc -= n;
486 as->argv += n;
489 static int parse_path_selector(struct arg_set *as, struct priority_group *pg,
490 struct dm_target *ti)
492 int r;
493 struct path_selector_type *pst;
494 unsigned ps_argc;
496 static struct param _params[] = {
497 {0, 1024, "invalid number of path selector args"},
500 pst = dm_get_path_selector(shift(as));
501 if (!pst) {
502 ti->error = "unknown path selector type";
503 return -EINVAL;
506 r = read_param(_params, shift(as), &ps_argc, &ti->error);
507 if (r)
508 return -EINVAL;
510 r = pst->create(&pg->ps, ps_argc, as->argv);
511 if (r) {
512 dm_put_path_selector(pst);
513 ti->error = "path selector constructor failed";
514 return r;
517 pg->ps.type = pst;
518 consume(as, ps_argc);
520 return 0;
523 static struct pgpath *parse_path(struct arg_set *as, struct path_selector *ps,
524 struct dm_target *ti)
526 int r;
527 struct pgpath *p;
529 /* we need at least a path arg */
530 if (as->argc < 1) {
531 ti->error = "no device given";
532 return NULL;
535 p = alloc_pgpath();
536 if (!p)
537 return NULL;
539 r = dm_get_device(ti, shift(as), ti->begin, ti->len,
540 dm_table_get_mode(ti->table), &p->path.dev);
541 if (r) {
542 ti->error = "error getting device";
543 goto bad;
546 r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
547 if (r) {
548 dm_put_device(ti, p->path.dev);
549 goto bad;
552 return p;
554 bad:
555 free_pgpath(p);
556 return NULL;
559 static struct priority_group *parse_priority_group(struct arg_set *as,
560 struct multipath *m,
561 struct dm_target *ti)
563 static struct param _params[] = {
564 {1, 1024, "invalid number of paths"},
565 {0, 1024, "invalid number of selector args"}
568 int r;
569 unsigned i, nr_selector_args, nr_params;
570 struct priority_group *pg;
572 if (as->argc < 2) {
573 as->argc = 0;
574 ti->error = "not enough priority group aruments";
575 return NULL;
578 pg = alloc_priority_group();
579 if (!pg) {
580 ti->error = "couldn't allocate priority group";
581 return NULL;
583 pg->m = m;
585 r = parse_path_selector(as, pg, ti);
586 if (r)
587 goto bad;
590 * read the paths
592 r = read_param(_params, shift(as), &pg->nr_pgpaths, &ti->error);
593 if (r)
594 goto bad;
596 r = read_param(_params + 1, shift(as), &nr_selector_args, &ti->error);
597 if (r)
598 goto bad;
600 nr_params = 1 + nr_selector_args;
601 for (i = 0; i < pg->nr_pgpaths; i++) {
602 struct pgpath *pgpath;
603 struct arg_set path_args;
605 if (as->argc < nr_params)
606 goto bad;
608 path_args.argc = nr_params;
609 path_args.argv = as->argv;
611 pgpath = parse_path(&path_args, &pg->ps, ti);
612 if (!pgpath)
613 goto bad;
615 pgpath->pg = pg;
616 list_add_tail(&pgpath->list, &pg->pgpaths);
617 consume(as, nr_params);
620 return pg;
622 bad:
623 free_priority_group(pg, ti);
624 return NULL;
627 static int parse_hw_handler(struct arg_set *as, struct multipath *m,
628 struct dm_target *ti)
630 int r;
631 struct hw_handler_type *hwht;
632 unsigned hw_argc;
634 static struct param _params[] = {
635 {0, 1024, "invalid number of hardware handler args"},
638 r = read_param(_params, shift(as), &hw_argc, &ti->error);
639 if (r)
640 return -EINVAL;
642 if (!hw_argc)
643 return 0;
645 hwht = dm_get_hw_handler(shift(as));
646 if (!hwht) {
647 ti->error = "unknown hardware handler type";
648 return -EINVAL;
651 r = hwht->create(&m->hw_handler, hw_argc - 1, as->argv);
652 if (r) {
653 dm_put_hw_handler(hwht);
654 ti->error = "hardware handler constructor failed";
655 return r;
658 m->hw_handler.type = hwht;
659 consume(as, hw_argc - 1);
661 return 0;
664 static int parse_features(struct arg_set *as, struct multipath *m,
665 struct dm_target *ti)
667 int r;
668 unsigned argc;
670 static struct param _params[] = {
671 {0, 1, "invalid number of feature args"},
674 r = read_param(_params, shift(as), &argc, &ti->error);
675 if (r)
676 return -EINVAL;
678 if (!argc)
679 return 0;
681 if (!strnicmp(shift(as), MESG_STR("queue_if_no_path")))
682 return queue_if_no_path(m, 1, 0);
683 else {
684 ti->error = "Unrecognised multipath feature request";
685 return -EINVAL;
689 static int multipath_ctr(struct dm_target *ti, unsigned int argc,
690 char **argv)
692 /* target parameters */
693 static struct param _params[] = {
694 {1, 1024, "invalid number of priority groups"},
695 {1, 1024, "invalid initial priority group number"},
698 int r;
699 struct multipath *m;
700 struct arg_set as;
701 unsigned pg_count = 0;
702 unsigned next_pg_num;
704 as.argc = argc;
705 as.argv = argv;
707 m = alloc_multipath();
708 if (!m) {
709 ti->error = "can't allocate multipath";
710 return -EINVAL;
713 r = parse_features(&as, m, ti);
714 if (r)
715 goto bad;
717 r = parse_hw_handler(&as, m, ti);
718 if (r)
719 goto bad;
721 r = read_param(_params, shift(&as), &m->nr_priority_groups, &ti->error);
722 if (r)
723 goto bad;
725 r = read_param(_params + 1, shift(&as), &next_pg_num, &ti->error);
726 if (r)
727 goto bad;
729 /* parse the priority groups */
730 while (as.argc) {
731 struct priority_group *pg;
733 pg = parse_priority_group(&as, m, ti);
734 if (!pg) {
735 r = -EINVAL;
736 goto bad;
739 m->nr_valid_paths += pg->nr_pgpaths;
740 list_add_tail(&pg->list, &m->priority_groups);
741 pg_count++;
742 pg->pg_num = pg_count;
743 if (!--next_pg_num)
744 m->next_pg = pg;
747 if (pg_count != m->nr_priority_groups) {
748 ti->error = "priority group count mismatch";
749 r = -EINVAL;
750 goto bad;
753 ti->private = m;
754 m->ti = ti;
756 return 0;
758 bad:
759 free_multipath(m);
760 return r;
763 static void multipath_dtr(struct dm_target *ti)
765 struct multipath *m = (struct multipath *) ti->private;
767 flush_workqueue(kmultipathd);
768 free_multipath(m);
772 * Map bios, recording original fields for later in case we have to resubmit
774 static int multipath_map(struct dm_target *ti, struct bio *bio,
775 union map_info *map_context)
777 int r;
778 struct mpath_io *mpio;
779 struct multipath *m = (struct multipath *) ti->private;
781 if (bio_barrier(bio))
782 return -EOPNOTSUPP;
784 mpio = mempool_alloc(m->mpio_pool, GFP_NOIO);
785 dm_bio_record(&mpio->details, bio);
787 map_context->ptr = mpio;
788 bio->bi_rw |= (1 << BIO_RW_FAILFAST);
789 r = map_io(m, bio, mpio, 0);
790 if (r < 0)
791 mempool_free(mpio, m->mpio_pool);
793 return r;
797 * Take a path out of use.
799 static int fail_path(struct pgpath *pgpath)
801 unsigned long flags;
802 struct multipath *m = pgpath->pg->m;
804 spin_lock_irqsave(&m->lock, flags);
806 if (!pgpath->path.is_active)
807 goto out;
809 DMWARN("Failing path %s.", pgpath->path.dev->name);
811 pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
812 pgpath->path.is_active = 0;
813 pgpath->fail_count++;
815 m->nr_valid_paths--;
817 if (pgpath == m->current_pgpath)
818 m->current_pgpath = NULL;
820 queue_work(kmultipathd, &m->trigger_event);
822 out:
823 spin_unlock_irqrestore(&m->lock, flags);
825 return 0;
829 * Reinstate a previously-failed path
831 static int reinstate_path(struct pgpath *pgpath)
833 int r = 0;
834 unsigned long flags;
835 struct multipath *m = pgpath->pg->m;
837 spin_lock_irqsave(&m->lock, flags);
839 if (pgpath->path.is_active)
840 goto out;
842 if (!pgpath->pg->ps.type) {
843 DMWARN("Reinstate path not supported by path selector %s",
844 pgpath->pg->ps.type->name);
845 r = -EINVAL;
846 goto out;
849 r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
850 if (r)
851 goto out;
853 pgpath->path.is_active = 1;
855 m->current_pgpath = NULL;
856 if (!m->nr_valid_paths++ && m->queue_size)
857 queue_work(kmultipathd, &m->process_queued_ios);
859 queue_work(kmultipathd, &m->trigger_event);
861 out:
862 spin_unlock_irqrestore(&m->lock, flags);
864 return r;
868 * Fail or reinstate all paths that match the provided struct dm_dev.
870 static int action_dev(struct multipath *m, struct dm_dev *dev,
871 action_fn action)
873 int r = 0;
874 struct pgpath *pgpath;
875 struct priority_group *pg;
877 list_for_each_entry(pg, &m->priority_groups, list) {
878 list_for_each_entry(pgpath, &pg->pgpaths, list) {
879 if (pgpath->path.dev == dev)
880 r = action(pgpath);
884 return r;
888 * Temporarily try to avoid having to use the specified PG
890 static void bypass_pg(struct multipath *m, struct priority_group *pg,
891 int bypassed)
893 unsigned long flags;
895 spin_lock_irqsave(&m->lock, flags);
897 pg->bypassed = bypassed;
898 m->current_pgpath = NULL;
899 m->current_pg = NULL;
901 spin_unlock_irqrestore(&m->lock, flags);
903 queue_work(kmultipathd, &m->trigger_event);
907 * Switch to using the specified PG from the next I/O that gets mapped
909 static int switch_pg_num(struct multipath *m, const char *pgstr)
911 struct priority_group *pg;
912 unsigned pgnum;
913 unsigned long flags;
915 if (!pgstr || (sscanf(pgstr, "%u", &pgnum) != 1) || !pgnum ||
916 (pgnum > m->nr_priority_groups)) {
917 DMWARN("invalid PG number supplied to switch_pg_num");
918 return -EINVAL;
921 spin_lock_irqsave(&m->lock, flags);
922 list_for_each_entry(pg, &m->priority_groups, list) {
923 pg->bypassed = 0;
924 if (--pgnum)
925 continue;
927 m->current_pgpath = NULL;
928 m->current_pg = NULL;
929 m->next_pg = pg;
931 spin_unlock_irqrestore(&m->lock, flags);
933 queue_work(kmultipathd, &m->trigger_event);
934 return 0;
938 * Set/clear bypassed status of a PG.
939 * PGs are numbered upwards from 1 in the order they were declared.
941 static int bypass_pg_num(struct multipath *m, const char *pgstr, int bypassed)
943 struct priority_group *pg;
944 unsigned pgnum;
946 if (!pgstr || (sscanf(pgstr, "%u", &pgnum) != 1) || !pgnum ||
947 (pgnum > m->nr_priority_groups)) {
948 DMWARN("invalid PG number supplied to bypass_pg");
949 return -EINVAL;
952 list_for_each_entry(pg, &m->priority_groups, list) {
953 if (!--pgnum)
954 break;
957 bypass_pg(m, pg, bypassed);
958 return 0;
962 * pg_init must call this when it has completed its initialisation
964 void dm_pg_init_complete(struct path *path, unsigned err_flags)
966 struct pgpath *pgpath = path_to_pgpath(path);
967 struct priority_group *pg = pgpath->pg;
968 struct multipath *m = pg->m;
969 unsigned long flags;
971 /* We insist on failing the path if the PG is already bypassed. */
972 if (err_flags && pg->bypassed)
973 err_flags |= MP_FAIL_PATH;
975 if (err_flags & MP_FAIL_PATH)
976 fail_path(pgpath);
978 if (err_flags & MP_BYPASS_PG)
979 bypass_pg(m, pg, 1);
981 spin_lock_irqsave(&m->lock, flags);
982 if (err_flags) {
983 m->current_pgpath = NULL;
984 m->current_pg = NULL;
985 } else if (!m->pg_init_required)
986 m->queue_io = 0;
988 m->pg_init_in_progress = 0;
989 queue_work(kmultipathd, &m->process_queued_ios);
990 spin_unlock_irqrestore(&m->lock, flags);
994 * end_io handling
996 static int do_end_io(struct multipath *m, struct bio *bio,
997 int error, struct mpath_io *mpio)
999 struct hw_handler *hwh = &m->hw_handler;
1000 unsigned err_flags = MP_FAIL_PATH; /* Default behavior */
1001 unsigned long flags;
1003 if (!error)
1004 return 0; /* I/O complete */
1006 if ((error == -EWOULDBLOCK) && bio_rw_ahead(bio))
1007 return error;
1009 if (error == -EOPNOTSUPP)
1010 return error;
1012 spin_lock_irqsave(&m->lock, flags);
1013 if (!m->nr_valid_paths) {
1014 if (!m->queue_if_no_path) {
1015 spin_unlock_irqrestore(&m->lock, flags);
1016 return -EIO;
1017 } else {
1018 spin_unlock_irqrestore(&m->lock, flags);
1019 goto requeue;
1022 spin_unlock_irqrestore(&m->lock, flags);
1024 if (hwh->type && hwh->type->error)
1025 err_flags = hwh->type->error(hwh, bio);
1027 if (mpio->pgpath) {
1028 if (err_flags & MP_FAIL_PATH)
1029 fail_path(mpio->pgpath);
1031 if (err_flags & MP_BYPASS_PG)
1032 bypass_pg(m, mpio->pgpath->pg, 1);
1035 if (err_flags & MP_ERROR_IO)
1036 return -EIO;
1038 requeue:
1039 dm_bio_restore(&mpio->details, bio);
1041 /* queue for the daemon to resubmit or fail */
1042 spin_lock_irqsave(&m->lock, flags);
1043 bio_list_add(&m->queued_ios, bio);
1044 m->queue_size++;
1045 if (!m->queue_io)
1046 queue_work(kmultipathd, &m->process_queued_ios);
1047 spin_unlock_irqrestore(&m->lock, flags);
1049 return 1; /* io not complete */
1052 static int multipath_end_io(struct dm_target *ti, struct bio *bio,
1053 int error, union map_info *map_context)
1055 struct multipath *m = (struct multipath *) ti->private;
1056 struct mpath_io *mpio = (struct mpath_io *) map_context->ptr;
1057 struct pgpath *pgpath = mpio->pgpath;
1058 struct path_selector *ps;
1059 int r;
1061 r = do_end_io(m, bio, error, mpio);
1062 if (pgpath) {
1063 ps = &pgpath->pg->ps;
1064 if (ps->type->end_io)
1065 ps->type->end_io(ps, &pgpath->path);
1067 if (r <= 0)
1068 mempool_free(mpio, m->mpio_pool);
1070 return r;
1074 * Suspend can't complete until all the I/O is processed so if
1075 * the last path fails we must error any remaining I/O.
1076 * Note that if the freeze_bdev fails while suspending, the
1077 * queue_if_no_path state is lost - userspace should reset it.
1079 static void multipath_presuspend(struct dm_target *ti)
1081 struct multipath *m = (struct multipath *) ti->private;
1083 queue_if_no_path(m, 0, 1);
1087 * Restore the queue_if_no_path setting.
1089 static void multipath_resume(struct dm_target *ti)
1091 struct multipath *m = (struct multipath *) ti->private;
1092 unsigned long flags;
1094 spin_lock_irqsave(&m->lock, flags);
1095 m->queue_if_no_path = m->saved_queue_if_no_path;
1096 spin_unlock_irqrestore(&m->lock, flags);
1100 * Info output has the following format:
1101 * num_multipath_feature_args [multipath_feature_args]*
1102 * num_handler_status_args [handler_status_args]*
1103 * num_groups init_group_number
1104 * [A|D|E num_ps_status_args [ps_status_args]*
1105 * num_paths num_selector_args
1106 * [path_dev A|F fail_count [selector_args]* ]+ ]+
1108 * Table output has the following format (identical to the constructor string):
1109 * num_feature_args [features_args]*
1110 * num_handler_args hw_handler [hw_handler_args]*
1111 * num_groups init_group_number
1112 * [priority selector-name num_ps_args [ps_args]*
1113 * num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
1115 static int multipath_status(struct dm_target *ti, status_type_t type,
1116 char *result, unsigned int maxlen)
1118 int sz = 0;
1119 unsigned long flags;
1120 struct multipath *m = (struct multipath *) ti->private;
1121 struct hw_handler *hwh = &m->hw_handler;
1122 struct priority_group *pg;
1123 struct pgpath *p;
1124 unsigned pg_num;
1125 char state;
1127 spin_lock_irqsave(&m->lock, flags);
1129 /* Features */
1130 if (type == STATUSTYPE_INFO)
1131 DMEMIT("1 %u ", m->queue_size);
1132 else if (m->queue_if_no_path)
1133 DMEMIT("1 queue_if_no_path ");
1134 else
1135 DMEMIT("0 ");
1137 if (hwh->type && hwh->type->status)
1138 sz += hwh->type->status(hwh, type, result + sz, maxlen - sz);
1139 else if (!hwh->type || type == STATUSTYPE_INFO)
1140 DMEMIT("0 ");
1141 else
1142 DMEMIT("1 %s ", hwh->type->name);
1144 DMEMIT("%u ", m->nr_priority_groups);
1146 if (m->next_pg)
1147 pg_num = m->next_pg->pg_num;
1148 else if (m->current_pg)
1149 pg_num = m->current_pg->pg_num;
1150 else
1151 pg_num = 1;
1153 DMEMIT("%u ", pg_num);
1155 switch (type) {
1156 case STATUSTYPE_INFO:
1157 list_for_each_entry(pg, &m->priority_groups, list) {
1158 if (pg->bypassed)
1159 state = 'D'; /* Disabled */
1160 else if (pg == m->current_pg)
1161 state = 'A'; /* Currently Active */
1162 else
1163 state = 'E'; /* Enabled */
1165 DMEMIT("%c ", state);
1167 if (pg->ps.type->status)
1168 sz += pg->ps.type->status(&pg->ps, NULL, type,
1169 result + sz,
1170 maxlen - sz);
1171 else
1172 DMEMIT("0 ");
1174 DMEMIT("%u %u ", pg->nr_pgpaths,
1175 pg->ps.type->info_args);
1177 list_for_each_entry(p, &pg->pgpaths, list) {
1178 DMEMIT("%s %s %u ", p->path.dev->name,
1179 p->path.is_active ? "A" : "F",
1180 p->fail_count);
1181 if (pg->ps.type->status)
1182 sz += pg->ps.type->status(&pg->ps,
1183 &p->path, type, result + sz,
1184 maxlen - sz);
1187 break;
1189 case STATUSTYPE_TABLE:
1190 list_for_each_entry(pg, &m->priority_groups, list) {
1191 DMEMIT("%s ", pg->ps.type->name);
1193 if (pg->ps.type->status)
1194 sz += pg->ps.type->status(&pg->ps, NULL, type,
1195 result + sz,
1196 maxlen - sz);
1197 else
1198 DMEMIT("0 ");
1200 DMEMIT("%u %u ", pg->nr_pgpaths,
1201 pg->ps.type->table_args);
1203 list_for_each_entry(p, &pg->pgpaths, list) {
1204 DMEMIT("%s ", p->path.dev->name);
1205 if (pg->ps.type->status)
1206 sz += pg->ps.type->status(&pg->ps,
1207 &p->path, type, result + sz,
1208 maxlen - sz);
1211 break;
1214 spin_unlock_irqrestore(&m->lock, flags);
1216 return 0;
1219 static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
1221 int r;
1222 struct dm_dev *dev;
1223 struct multipath *m = (struct multipath *) ti->private;
1224 action_fn action;
1226 if (argc == 1) {
1227 if (!strnicmp(argv[0], MESG_STR("queue_if_no_path")))
1228 return queue_if_no_path(m, 1, 0);
1229 else if (!strnicmp(argv[0], MESG_STR("fail_if_no_path")))
1230 return queue_if_no_path(m, 0, 0);
1233 if (argc != 2)
1234 goto error;
1236 if (!strnicmp(argv[0], MESG_STR("disable_group")))
1237 return bypass_pg_num(m, argv[1], 1);
1238 else if (!strnicmp(argv[0], MESG_STR("enable_group")))
1239 return bypass_pg_num(m, argv[1], 0);
1240 else if (!strnicmp(argv[0], MESG_STR("switch_group")))
1241 return switch_pg_num(m, argv[1]);
1242 else if (!strnicmp(argv[0], MESG_STR("reinstate_path")))
1243 action = reinstate_path;
1244 else if (!strnicmp(argv[0], MESG_STR("fail_path")))
1245 action = fail_path;
1246 else
1247 goto error;
1249 r = dm_get_device(ti, argv[1], ti->begin, ti->len,
1250 dm_table_get_mode(ti->table), &dev);
1251 if (r) {
1252 DMWARN("message: error getting device %s",
1253 argv[1]);
1254 return -EINVAL;
1257 r = action_dev(m, dev, action);
1259 dm_put_device(ti, dev);
1261 return r;
1263 error:
1264 DMWARN("Unrecognised multipath message received.");
1265 return -EINVAL;
1268 /*-----------------------------------------------------------------
1269 * Module setup
1270 *---------------------------------------------------------------*/
1271 static struct target_type multipath_target = {
1272 .name = "multipath",
1273 .version = {1, 0, 4},
1274 .module = THIS_MODULE,
1275 .ctr = multipath_ctr,
1276 .dtr = multipath_dtr,
1277 .map = multipath_map,
1278 .end_io = multipath_end_io,
1279 .presuspend = multipath_presuspend,
1280 .resume = multipath_resume,
1281 .status = multipath_status,
1282 .message = multipath_message,
1285 static int __init dm_multipath_init(void)
1287 int r;
1289 /* allocate a slab for the dm_ios */
1290 _mpio_cache = kmem_cache_create("dm_mpath", sizeof(struct mpath_io),
1291 0, 0, NULL, NULL);
1292 if (!_mpio_cache)
1293 return -ENOMEM;
1295 r = dm_register_target(&multipath_target);
1296 if (r < 0) {
1297 DMERR("%s: register failed %d", multipath_target.name, r);
1298 kmem_cache_destroy(_mpio_cache);
1299 return -EINVAL;
1302 kmultipathd = create_workqueue("kmpathd");
1303 if (!kmultipathd) {
1304 DMERR("%s: failed to create workqueue kmpathd",
1305 multipath_target.name);
1306 dm_unregister_target(&multipath_target);
1307 kmem_cache_destroy(_mpio_cache);
1308 return -ENOMEM;
1311 DMINFO("version %u.%u.%u loaded",
1312 multipath_target.version[0], multipath_target.version[1],
1313 multipath_target.version[2]);
1315 return r;
1318 static void __exit dm_multipath_exit(void)
1320 int r;
1322 destroy_workqueue(kmultipathd);
1324 r = dm_unregister_target(&multipath_target);
1325 if (r < 0)
1326 DMERR("%s: target unregister failed %d",
1327 multipath_target.name, r);
1328 kmem_cache_destroy(_mpio_cache);
1331 EXPORT_SYMBOL_GPL(dm_pg_init_complete);
1333 module_init(dm_multipath_init);
1334 module_exit(dm_multipath_exit);
1336 MODULE_DESCRIPTION(DM_NAME " multipath target");
1337 MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
1338 MODULE_LICENSE("GPL");