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.
8 #include <linux/device-mapper.h>
10 #include "dm-path-selector.h"
11 #include "dm-uevent.h"
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 <scsi/scsi_dh.h>
22 #include <scsi/scsi_eh.h>
23 #include <asm/atomic.h>
25 #define DM_MSG_PREFIX "multipath"
26 #define MESG_STR(x) x, sizeof(x)
30 struct list_head list;
32 struct priority_group *pg; /* Owning PG */
33 unsigned is_active; /* Path status */
34 unsigned fail_count; /* Cumulative failure count */
37 struct work_struct deactivate_path;
38 struct work_struct activate_path;
41 #define path_to_pgpath(__pgp) container_of((__pgp), struct pgpath, path)
44 * Paths are grouped into Priority Groups and numbered from 1 upwards.
45 * Each has a path selector which controls which path gets used.
47 struct priority_group {
48 struct list_head list;
50 struct multipath *m; /* Owning multipath instance */
51 struct path_selector ps;
53 unsigned pg_num; /* Reference number */
54 unsigned bypassed; /* Temporarily bypass this PG? */
56 unsigned nr_pgpaths; /* Number of paths in PG */
57 struct list_head pgpaths;
60 /* Multipath context */
62 struct list_head list;
67 const char *hw_handler_name;
68 char *hw_handler_params;
69 unsigned nr_priority_groups;
70 struct list_head priority_groups;
71 unsigned pg_init_required; /* pg_init needs calling? */
72 unsigned pg_init_in_progress; /* Only one pg_init allowed at once */
74 unsigned nr_valid_paths; /* Total number of usable paths */
75 struct pgpath *current_pgpath;
76 struct priority_group *current_pg;
77 struct priority_group *next_pg; /* Switch to this PG if set */
78 unsigned repeat_count; /* I/Os left before calling PS again */
80 unsigned queue_io; /* Must we queue all I/O? */
81 unsigned queue_if_no_path; /* Queue I/O if last path fails? */
82 unsigned saved_queue_if_no_path;/* Saved state during suspension */
83 unsigned pg_init_retries; /* Number of times to retry pg_init */
84 unsigned pg_init_count; /* Number of times pg_init called */
86 struct work_struct process_queued_ios;
87 struct list_head queued_ios;
90 struct work_struct trigger_event;
93 * We must use a mempool of dm_mpath_io structs so that we
94 * can resubmit bios on error.
100 * Context information attached to each bio we process.
103 struct pgpath *pgpath;
105 char sense[SCSI_SENSE_BUFFERSIZE];
108 typedef int (*action_fn) (struct pgpath *pgpath);
110 #define MIN_IOS 256 /* Mempool size */
112 static struct kmem_cache *_mpio_cache;
114 static struct workqueue_struct *kmultipathd, *kmpath_handlerd;
115 static void process_queued_ios(struct work_struct *work);
116 static void trigger_event(struct work_struct *work);
117 static void activate_path(struct work_struct *work);
118 static void deactivate_path(struct work_struct *work);
121 /*-----------------------------------------------
122 * Allocation routines
123 *-----------------------------------------------*/
125 static struct pgpath *alloc_pgpath(void)
127 struct pgpath *pgpath = kzalloc(sizeof(*pgpath), GFP_KERNEL);
130 pgpath->is_active = 1;
131 INIT_WORK(&pgpath->deactivate_path, deactivate_path);
132 INIT_WORK(&pgpath->activate_path, activate_path);
138 static void free_pgpath(struct pgpath *pgpath)
143 static void deactivate_path(struct work_struct *work)
145 struct pgpath *pgpath =
146 container_of(work, struct pgpath, deactivate_path);
148 if (pgpath->path.dev)
149 blk_abort_queue(pgpath->path.dev->bdev->bd_disk->queue);
152 static struct priority_group *alloc_priority_group(void)
154 struct priority_group *pg;
156 pg = kzalloc(sizeof(*pg), GFP_KERNEL);
159 INIT_LIST_HEAD(&pg->pgpaths);
164 static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti)
166 struct pgpath *pgpath, *tmp;
167 struct multipath *m = ti->private;
169 list_for_each_entry_safe(pgpath, tmp, pgpaths, list) {
170 list_del(&pgpath->list);
171 dm_put_device(ti, pgpath->path.dev);
176 static void free_priority_group(struct priority_group *pg,
177 struct dm_target *ti)
179 struct path_selector *ps = &pg->ps;
182 ps->type->destroy(ps);
183 dm_put_path_selector(ps->type);
186 free_pgpaths(&pg->pgpaths, ti);
190 static struct multipath *alloc_multipath(struct dm_target *ti)
194 m = kzalloc(sizeof(*m), GFP_KERNEL);
196 INIT_LIST_HEAD(&m->priority_groups);
197 INIT_LIST_HEAD(&m->queued_ios);
198 spin_lock_init(&m->lock);
200 INIT_WORK(&m->process_queued_ios, process_queued_ios);
201 INIT_WORK(&m->trigger_event, trigger_event);
202 m->mpio_pool = mempool_create_slab_pool(MIN_IOS, _mpio_cache);
214 static void free_multipath(struct multipath *m)
216 struct priority_group *pg, *tmp;
218 list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) {
220 free_priority_group(pg, m->ti);
223 kfree(m->hw_handler_name);
224 kfree(m->hw_handler_params);
225 mempool_destroy(m->mpio_pool);
230 /*-----------------------------------------------
232 *-----------------------------------------------*/
234 static void __switch_pg(struct multipath *m, struct pgpath *pgpath)
236 m->current_pg = pgpath->pg;
238 /* Must we initialise the PG first, and queue I/O till it's ready? */
239 if (m->hw_handler_name) {
240 m->pg_init_required = 1;
243 m->pg_init_required = 0;
247 m->pg_init_count = 0;
250 static int __choose_path_in_pg(struct multipath *m, struct priority_group *pg,
253 struct dm_path *path;
255 path = pg->ps.type->select_path(&pg->ps, &m->repeat_count, nr_bytes);
259 m->current_pgpath = path_to_pgpath(path);
261 if (!m->current_pgpath->path.dev) {
262 m->current_pgpath = NULL;
266 if (m->current_pg != pg)
267 __switch_pg(m, m->current_pgpath);
272 static void __choose_pgpath(struct multipath *m, size_t nr_bytes)
274 struct priority_group *pg;
275 unsigned bypassed = 1;
277 if (!m->nr_valid_paths)
280 /* Were we instructed to switch PG? */
284 if (!__choose_path_in_pg(m, pg, nr_bytes))
288 /* Don't change PG until it has no remaining paths */
289 if (m->current_pg && !__choose_path_in_pg(m, m->current_pg, nr_bytes))
293 * Loop through priority groups until we find a valid path.
294 * First time we skip PGs marked 'bypassed'.
295 * Second time we only try the ones we skipped.
298 list_for_each_entry(pg, &m->priority_groups, list) {
299 if (pg->bypassed == bypassed)
301 if (!__choose_path_in_pg(m, pg, nr_bytes))
304 } while (bypassed--);
307 m->current_pgpath = NULL;
308 m->current_pg = NULL;
312 * Check whether bios must be queued in the device-mapper core rather
313 * than here in the target.
315 * m->lock must be held on entry.
317 * If m->queue_if_no_path and m->saved_queue_if_no_path hold the
318 * same value then we are not between multipath_presuspend()
319 * and multipath_resume() calls and we have no need to check
320 * for the DMF_NOFLUSH_SUSPENDING flag.
322 static int __must_push_back(struct multipath *m)
324 return (m->queue_if_no_path != m->saved_queue_if_no_path &&
325 dm_noflush_suspending(m->ti));
328 static int map_io(struct multipath *m, struct request *clone,
329 struct dm_mpath_io *mpio, unsigned was_queued)
331 int r = DM_MAPIO_REMAPPED;
332 size_t nr_bytes = blk_rq_bytes(clone);
334 struct pgpath *pgpath;
335 struct block_device *bdev;
337 spin_lock_irqsave(&m->lock, flags);
339 /* Do we need to select a new pgpath? */
340 if (!m->current_pgpath ||
341 (!m->queue_io && (m->repeat_count && --m->repeat_count == 0)))
342 __choose_pgpath(m, nr_bytes);
344 pgpath = m->current_pgpath;
349 if ((pgpath && m->queue_io) ||
350 (!pgpath && m->queue_if_no_path)) {
351 /* Queue for the daemon to resubmit */
352 list_add_tail(&clone->queuelist, &m->queued_ios);
354 if ((m->pg_init_required && !m->pg_init_in_progress) ||
356 queue_work(kmultipathd, &m->process_queued_ios);
358 r = DM_MAPIO_SUBMITTED;
360 bdev = pgpath->path.dev->bdev;
361 clone->q = bdev_get_queue(bdev);
362 clone->rq_disk = bdev->bd_disk;
363 } else if (__must_push_back(m))
364 r = DM_MAPIO_REQUEUE;
366 r = -EIO; /* Failed */
368 mpio->pgpath = pgpath;
369 mpio->nr_bytes = nr_bytes;
371 if (r == DM_MAPIO_REMAPPED && pgpath->pg->ps.type->start_io)
372 pgpath->pg->ps.type->start_io(&pgpath->pg->ps, &pgpath->path,
375 spin_unlock_irqrestore(&m->lock, flags);
381 * If we run out of usable paths, should we queue I/O or error it?
383 static int queue_if_no_path(struct multipath *m, unsigned queue_if_no_path,
384 unsigned save_old_value)
388 spin_lock_irqsave(&m->lock, flags);
391 m->saved_queue_if_no_path = m->queue_if_no_path;
393 m->saved_queue_if_no_path = queue_if_no_path;
394 m->queue_if_no_path = queue_if_no_path;
395 if (!m->queue_if_no_path && m->queue_size)
396 queue_work(kmultipathd, &m->process_queued_ios);
398 spin_unlock_irqrestore(&m->lock, flags);
403 /*-----------------------------------------------------------------
404 * The multipath daemon is responsible for resubmitting queued ios.
405 *---------------------------------------------------------------*/
407 static void dispatch_queued_ios(struct multipath *m)
411 struct dm_mpath_io *mpio;
412 union map_info *info;
413 struct request *clone, *n;
416 spin_lock_irqsave(&m->lock, flags);
417 list_splice_init(&m->queued_ios, &cl);
418 spin_unlock_irqrestore(&m->lock, flags);
420 list_for_each_entry_safe(clone, n, &cl, queuelist) {
421 list_del_init(&clone->queuelist);
423 info = dm_get_rq_mapinfo(clone);
426 r = map_io(m, clone, mpio, 1);
428 mempool_free(mpio, m->mpio_pool);
429 dm_kill_unmapped_request(clone, r);
430 } else if (r == DM_MAPIO_REMAPPED)
431 dm_dispatch_request(clone);
432 else if (r == DM_MAPIO_REQUEUE) {
433 mempool_free(mpio, m->mpio_pool);
434 dm_requeue_unmapped_request(clone);
439 static void process_queued_ios(struct work_struct *work)
441 struct multipath *m =
442 container_of(work, struct multipath, process_queued_ios);
443 struct pgpath *pgpath = NULL, *tmp;
444 unsigned must_queue = 1;
447 spin_lock_irqsave(&m->lock, flags);
452 if (!m->current_pgpath)
453 __choose_pgpath(m, 0);
455 pgpath = m->current_pgpath;
457 if ((pgpath && !m->queue_io) ||
458 (!pgpath && !m->queue_if_no_path))
461 if (m->pg_init_required && !m->pg_init_in_progress && pgpath) {
463 m->pg_init_required = 0;
464 list_for_each_entry(tmp, &pgpath->pg->pgpaths, list) {
465 if (queue_work(kmpath_handlerd, &tmp->activate_path))
466 m->pg_init_in_progress++;
470 spin_unlock_irqrestore(&m->lock, flags);
472 dispatch_queued_ios(m);
476 * An event is triggered whenever a path is taken out of use.
477 * Includes path failure and PG bypass.
479 static void trigger_event(struct work_struct *work)
481 struct multipath *m =
482 container_of(work, struct multipath, trigger_event);
484 dm_table_event(m->ti->table);
487 /*-----------------------------------------------------------------
488 * Constructor/argument parsing:
489 * <#multipath feature args> [<arg>]*
490 * <#hw_handler args> [hw_handler [<arg>]*]
492 * <initial priority group>
493 * [<selector> <#selector args> [<arg>]*
494 * <#paths> <#per-path selector args>
495 * [<path> [<arg>]* ]+ ]+
496 *---------------------------------------------------------------*/
503 static int read_param(struct param *param, char *str, unsigned *v, char **error)
506 (sscanf(str, "%u", v) != 1) ||
509 *error = param->error;
521 static char *shift(struct arg_set *as)
535 static void consume(struct arg_set *as, unsigned n)
537 BUG_ON (as->argc < n);
542 static int parse_path_selector(struct arg_set *as, struct priority_group *pg,
543 struct dm_target *ti)
546 struct path_selector_type *pst;
549 static struct param _params[] = {
550 {0, 1024, "invalid number of path selector args"},
553 pst = dm_get_path_selector(shift(as));
555 ti->error = "unknown path selector type";
559 r = read_param(_params, shift(as), &ps_argc, &ti->error);
561 dm_put_path_selector(pst);
565 if (ps_argc > as->argc) {
566 dm_put_path_selector(pst);
567 ti->error = "not enough arguments for path selector";
571 r = pst->create(&pg->ps, ps_argc, as->argv);
573 dm_put_path_selector(pst);
574 ti->error = "path selector constructor failed";
579 consume(as, ps_argc);
584 static struct pgpath *parse_path(struct arg_set *as, struct path_selector *ps,
585 struct dm_target *ti)
590 struct multipath *m = ti->private;
592 /* we need at least a path arg */
594 ti->error = "no device given";
595 return ERR_PTR(-EINVAL);
600 return ERR_PTR(-ENOMEM);
603 r = dm_get_device(ti, path, ti->begin, ti->len,
604 dm_table_get_mode(ti->table), &p->path.dev);
606 unsigned major, minor;
608 /* Try to add a failed device */
609 if (r == -ENXIO && sscanf(path, "%u:%u", &major, &minor) == 2) {
612 /* Extract the major/minor numbers */
613 dev = MKDEV(major, minor);
614 if (MAJOR(dev) != major || MINOR(dev) != minor) {
615 /* Nice try, didn't work */
616 DMWARN("Invalid device path %s", path);
617 ti->error = "error converting devnum";
620 DMWARN("adding disabled device %d:%d", major, minor);
622 format_dev_t(p->path.pdev, dev);
625 ti->error = "error getting device";
629 memcpy(p->path.pdev, p->path.dev->name, 16);
633 struct request_queue *q = bdev_get_queue(p->path.dev->bdev);
635 if (m->hw_handler_name) {
636 r = scsi_dh_attach(q, m->hw_handler_name);
639 * Already attached to different hw_handler,
640 * try to reattach with correct one.
643 r = scsi_dh_attach(q, m->hw_handler_name);
646 ti->error = "error attaching hardware handler";
647 dm_put_device(ti, p->path.dev);
651 /* Play safe and detach hardware handler */
655 if (m->hw_handler_params) {
656 r = scsi_dh_set_params(q, m->hw_handler_params);
658 ti->error = "unable to set hardware "
659 "handler parameters";
661 dm_put_device(ti, p->path.dev);
667 r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
669 dm_put_device(ti, p->path.dev);
674 ps->type->fail_path(ps, &p->path);
685 static struct priority_group *parse_priority_group(struct arg_set *as,
688 static struct param _params[] = {
689 {1, 1024, "invalid number of paths"},
690 {0, 1024, "invalid number of selector args"}
694 unsigned i, nr_selector_args, nr_params;
695 struct priority_group *pg;
696 struct dm_target *ti = m->ti;
700 ti->error = "not enough priority group arguments";
701 return ERR_PTR(-EINVAL);
704 pg = alloc_priority_group();
706 ti->error = "couldn't allocate priority group";
707 return ERR_PTR(-ENOMEM);
711 r = parse_path_selector(as, pg, ti);
718 r = read_param(_params, shift(as), &pg->nr_pgpaths, &ti->error);
722 r = read_param(_params + 1, shift(as), &nr_selector_args, &ti->error);
726 nr_params = 1 + nr_selector_args;
727 for (i = 0; i < pg->nr_pgpaths; i++) {
728 struct pgpath *pgpath;
729 struct arg_set path_args;
731 if (as->argc < nr_params) {
732 ti->error = "not enough path parameters";
736 path_args.argc = nr_params;
737 path_args.argv = as->argv;
739 pgpath = parse_path(&path_args, &pg->ps, ti);
740 if (IS_ERR(pgpath)) {
746 list_add_tail(&pgpath->list, &pg->pgpaths);
747 consume(as, nr_params);
753 free_priority_group(pg, ti);
757 static int parse_hw_handler(struct arg_set *as, struct multipath *m)
761 struct dm_target *ti = m->ti;
763 static struct param _params[] = {
764 {0, 1024, "invalid number of hardware handler args"},
767 if (read_param(_params, shift(as), &hw_argc, &ti->error))
773 if (hw_argc > as->argc) {
774 ti->error = "not enough arguments for hardware handler";
778 m->hw_handler_name = kstrdup(shift(as), GFP_KERNEL);
779 request_module("scsi_dh_%s", m->hw_handler_name);
780 if (scsi_dh_handler_exist(m->hw_handler_name) == 0) {
781 ti->error = "unknown hardware handler type";
790 for (i = 0; i <= hw_argc - 2; i++)
791 len += strlen(as->argv[i]) + 1;
792 p = m->hw_handler_params = kzalloc(len, GFP_KERNEL);
794 ti->error = "memory allocation failed";
798 j = sprintf(p, "%d", hw_argc - 1);
799 for (i = 0, p+=j+1; i <= hw_argc - 2; i++, p+=j+1)
800 j = sprintf(p, "%s", as->argv[i]);
802 consume(as, hw_argc - 1);
806 kfree(m->hw_handler_name);
807 m->hw_handler_name = NULL;
811 static int parse_features(struct arg_set *as, struct multipath *m)
815 struct dm_target *ti = m->ti;
816 const char *param_name;
818 static struct param _params[] = {
819 {0, 3, "invalid number of feature args"},
820 {1, 50, "pg_init_retries must be between 1 and 50"},
823 r = read_param(_params, shift(as), &argc, &ti->error);
831 param_name = shift(as);
834 if (!strnicmp(param_name, MESG_STR("queue_if_no_path"))) {
835 r = queue_if_no_path(m, 1, 0);
839 if (!strnicmp(param_name, MESG_STR("pg_init_retries")) &&
841 r = read_param(_params + 1, shift(as),
842 &m->pg_init_retries, &ti->error);
847 ti->error = "Unrecognised multipath feature request";
849 } while (argc && !r);
854 static int multipath_ctr(struct dm_target *ti, unsigned int argc,
857 /* target parameters */
858 static struct param _params[] = {
859 {0, 1024, "invalid number of priority groups"},
860 {0, 1024, "invalid initial priority group number"},
866 unsigned pg_count = 0;
867 unsigned next_pg_num;
872 m = alloc_multipath(ti);
874 ti->error = "can't allocate multipath";
878 r = parse_features(&as, m);
882 r = parse_hw_handler(&as, m);
886 r = read_param(_params, shift(&as), &m->nr_priority_groups, &ti->error);
890 r = read_param(_params + 1, shift(&as), &next_pg_num, &ti->error);
894 /* parse the priority groups */
896 struct priority_group *pg;
898 pg = parse_priority_group(&as, m);
904 m->nr_valid_paths += pg->nr_pgpaths;
905 list_add_tail(&pg->list, &m->priority_groups);
907 pg->pg_num = pg_count;
912 if (pg_count != m->nr_priority_groups) {
913 ti->error = "priority group count mismatch";
918 ti->num_flush_requests = 1;
927 static void multipath_dtr(struct dm_target *ti)
929 struct multipath *m = (struct multipath *) ti->private;
931 flush_workqueue(kmpath_handlerd);
932 flush_workqueue(kmultipathd);
933 flush_scheduled_work();
938 * Map cloned requests
940 static int multipath_map(struct dm_target *ti, struct request *clone,
941 union map_info *map_context)
944 struct dm_mpath_io *mpio;
945 struct multipath *m = (struct multipath *) ti->private;
947 mpio = mempool_alloc(m->mpio_pool, GFP_ATOMIC);
949 /* ENOMEM, requeue */
950 return DM_MAPIO_REQUEUE;
951 memset(mpio, 0, sizeof(*mpio));
953 map_context->ptr = mpio;
954 clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
955 /* Always attach a sense buffer */
957 clone->sense = mpio->sense;
958 r = map_io(m, clone, mpio, 0);
959 if (r < 0 || r == DM_MAPIO_REQUEUE)
960 mempool_free(mpio, m->mpio_pool);
966 * Take a path out of use.
968 static int fail_path(struct pgpath *pgpath)
971 struct multipath *m = pgpath->pg->m;
973 spin_lock_irqsave(&m->lock, flags);
975 if (!pgpath->is_active)
978 DMWARN("Failing path %s.", pgpath->path.pdev);
980 pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
981 pgpath->is_active = 0;
982 pgpath->fail_count++;
986 if (pgpath == m->current_pgpath)
987 m->current_pgpath = NULL;
989 dm_path_uevent(DM_UEVENT_PATH_FAILED, m->ti,
990 pgpath->path.pdev, m->nr_valid_paths);
992 schedule_work(&m->trigger_event);
993 queue_work(kmultipathd, &pgpath->deactivate_path);
996 spin_unlock_irqrestore(&m->lock, flags);
1002 * Reinstate a previously-failed path
1004 static int reinstate_path(struct pgpath *pgpath)
1007 unsigned long flags;
1008 struct multipath *m = pgpath->pg->m;
1010 spin_lock_irqsave(&m->lock, flags);
1012 if (pgpath->is_active)
1015 if (!pgpath->path.dev) {
1016 DMWARN("Cannot reinstate disabled path %s", pgpath->path.pdev);
1021 if (!pgpath->pg->ps.type->reinstate_path) {
1022 DMWARN("Reinstate path not supported by path selector %s",
1023 pgpath->pg->ps.type->name);
1028 r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
1032 pgpath->is_active = 1;
1034 if (!m->nr_valid_paths++ && m->queue_size) {
1035 m->current_pgpath = NULL;
1036 queue_work(kmultipathd, &m->process_queued_ios);
1037 } else if (m->hw_handler_name && (m->current_pg == pgpath->pg)) {
1038 if (queue_work(kmpath_handlerd, &pgpath->activate_path))
1039 m->pg_init_in_progress++;
1042 dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti,
1043 pgpath->path.pdev, m->nr_valid_paths);
1045 schedule_work(&m->trigger_event);
1048 spin_unlock_irqrestore(&m->lock, flags);
1054 * Fail or reinstate all paths that match the provided struct dm_dev.
1056 static int action_dev(struct multipath *m, struct dm_dev *dev,
1060 struct pgpath *pgpath;
1061 struct priority_group *pg;
1066 list_for_each_entry(pg, &m->priority_groups, list) {
1067 list_for_each_entry(pgpath, &pg->pgpaths, list) {
1068 if (pgpath->path.dev == dev)
1077 * Temporarily try to avoid having to use the specified PG
1079 static void bypass_pg(struct multipath *m, struct priority_group *pg,
1082 unsigned long flags;
1084 spin_lock_irqsave(&m->lock, flags);
1086 pg->bypassed = bypassed;
1087 m->current_pgpath = NULL;
1088 m->current_pg = NULL;
1090 spin_unlock_irqrestore(&m->lock, flags);
1092 schedule_work(&m->trigger_event);
1096 * Switch to using the specified PG from the next I/O that gets mapped
1098 static int switch_pg_num(struct multipath *m, const char *pgstr)
1100 struct priority_group *pg;
1102 unsigned long flags;
1104 if (!pgstr || (sscanf(pgstr, "%u", &pgnum) != 1) || !pgnum ||
1105 (pgnum > m->nr_priority_groups)) {
1106 DMWARN("invalid PG number supplied to switch_pg_num");
1110 spin_lock_irqsave(&m->lock, flags);
1111 list_for_each_entry(pg, &m->priority_groups, list) {
1116 m->current_pgpath = NULL;
1117 m->current_pg = NULL;
1120 spin_unlock_irqrestore(&m->lock, flags);
1122 schedule_work(&m->trigger_event);
1127 * Set/clear bypassed status of a PG.
1128 * PGs are numbered upwards from 1 in the order they were declared.
1130 static int bypass_pg_num(struct multipath *m, const char *pgstr, int bypassed)
1132 struct priority_group *pg;
1135 if (!pgstr || (sscanf(pgstr, "%u", &pgnum) != 1) || !pgnum ||
1136 (pgnum > m->nr_priority_groups)) {
1137 DMWARN("invalid PG number supplied to bypass_pg");
1141 list_for_each_entry(pg, &m->priority_groups, list) {
1146 bypass_pg(m, pg, bypassed);
1151 * Should we retry pg_init immediately?
1153 static int pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath)
1155 unsigned long flags;
1156 int limit_reached = 0;
1158 spin_lock_irqsave(&m->lock, flags);
1160 if (m->pg_init_count <= m->pg_init_retries)
1161 m->pg_init_required = 1;
1165 spin_unlock_irqrestore(&m->lock, flags);
1167 return limit_reached;
1170 static void pg_init_done(void *data, int errors)
1172 struct dm_path *path = data;
1173 struct pgpath *pgpath = path_to_pgpath(path);
1174 struct priority_group *pg = pgpath->pg;
1175 struct multipath *m = pg->m;
1176 unsigned long flags;
1178 /* device or driver problems */
1183 if (!m->hw_handler_name) {
1187 DMERR("Cannot failover device because scsi_dh_%s was not "
1188 "loaded.", m->hw_handler_name);
1190 * Fail path for now, so we do not ping pong
1194 case SCSI_DH_DEV_TEMP_BUSY:
1196 * Probably doing something like FW upgrade on the
1197 * controller so try the other pg.
1199 bypass_pg(m, pg, 1);
1201 /* TODO: For SCSI_DH_RETRY we should wait a couple seconds */
1203 case SCSI_DH_IMM_RETRY:
1204 case SCSI_DH_RES_TEMP_UNAVAIL:
1205 if (pg_init_limit_reached(m, pgpath))
1211 * We probably do not want to fail the path for a device
1212 * error, but this is what the old dm did. In future
1213 * patches we can do more advanced handling.
1218 spin_lock_irqsave(&m->lock, flags);
1220 if (pgpath == m->current_pgpath) {
1221 DMERR("Could not failover device. Error %d.", errors);
1222 m->current_pgpath = NULL;
1223 m->current_pg = NULL;
1225 } else if (!m->pg_init_required) {
1230 m->pg_init_in_progress--;
1231 if (!m->pg_init_in_progress)
1232 queue_work(kmultipathd, &m->process_queued_ios);
1233 spin_unlock_irqrestore(&m->lock, flags);
1236 static void activate_path(struct work_struct *work)
1238 struct pgpath *pgpath =
1239 container_of(work, struct pgpath, activate_path);
1241 if (pgpath->path.dev)
1242 scsi_dh_activate(bdev_get_queue(pgpath->path.dev->bdev),
1243 pg_init_done, &pgpath->path);
1247 * Evaluate scsi return code
1249 static int eval_scsi_error(int result, char *sense, int sense_len)
1251 struct scsi_sense_hdr sshdr;
1252 int r = DM_ENDIO_REQUEUE;
1254 if (host_byte(result) != DID_OK)
1257 if (msg_byte(result) != COMMAND_COMPLETE)
1260 if (status_byte(result) == RESERVATION_CONFLICT)
1261 /* Do not retry here, possible data corruption */
1264 if (status_byte(result) == CHECK_CONDITION &&
1265 !scsi_normalize_sense(sense, sense_len, &sshdr)) {
1267 switch (sshdr.sense_key) {
1272 case VOLUME_OVERFLOW:
1285 static int do_end_io(struct multipath *m, struct request *clone,
1286 int error, struct dm_mpath_io *mpio)
1289 * We don't queue any clone request inside the multipath target
1290 * during end I/O handling, since those clone requests don't have
1291 * bio clones. If we queue them inside the multipath target,
1292 * we need to make bio clones, that requires memory allocation.
1293 * (See drivers/md/dm.c:end_clone_bio() about why the clone requests
1294 * don't have bio clones.)
1295 * Instead of queueing the clone request here, we queue the original
1296 * request into dm core, which will remake a clone request and
1297 * clone bios for it and resubmit it later.
1299 int r = DM_ENDIO_REQUEUE;
1300 unsigned long flags;
1302 if (!error && !clone->errors)
1303 return 0; /* I/O complete */
1305 if (error == -EOPNOTSUPP)
1308 r = eval_scsi_error(clone->errors, clone->sense, clone->sense_len);
1309 if (r != DM_ENDIO_REQUEUE)
1313 fail_path(mpio->pgpath);
1315 spin_lock_irqsave(&m->lock, flags);
1316 if (!m->nr_valid_paths && !m->queue_if_no_path && !__must_push_back(m))
1318 spin_unlock_irqrestore(&m->lock, flags);
1323 static int multipath_end_io(struct dm_target *ti, struct request *clone,
1324 int error, union map_info *map_context)
1326 struct multipath *m = ti->private;
1327 struct dm_mpath_io *mpio = map_context->ptr;
1328 struct pgpath *pgpath = mpio->pgpath;
1329 struct path_selector *ps;
1332 r = do_end_io(m, clone, error, mpio);
1334 ps = &pgpath->pg->ps;
1335 if (ps->type->end_io)
1336 ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
1338 if (clone->sense == mpio->sense) {
1339 clone->sense = NULL;
1340 clone->sense_len = 0;
1342 mempool_free(mpio, m->mpio_pool);
1348 * Suspend can't complete until all the I/O is processed so if
1349 * the last path fails we must error any remaining I/O.
1350 * Note that if the freeze_bdev fails while suspending, the
1351 * queue_if_no_path state is lost - userspace should reset it.
1353 static void multipath_presuspend(struct dm_target *ti)
1355 struct multipath *m = (struct multipath *) ti->private;
1357 queue_if_no_path(m, 0, 1);
1361 * Restore the queue_if_no_path setting.
1363 static void multipath_resume(struct dm_target *ti)
1365 struct multipath *m = (struct multipath *) ti->private;
1366 unsigned long flags;
1368 spin_lock_irqsave(&m->lock, flags);
1369 m->queue_if_no_path = m->saved_queue_if_no_path;
1370 spin_unlock_irqrestore(&m->lock, flags);
1374 * Info output has the following format:
1375 * num_multipath_feature_args [multipath_feature_args]*
1376 * num_handler_status_args [handler_status_args]*
1377 * num_groups init_group_number
1378 * [A|D|E num_ps_status_args [ps_status_args]*
1379 * num_paths num_selector_args
1380 * [path_dev A|F fail_count [selector_args]* ]+ ]+
1382 * Table output has the following format (identical to the constructor string):
1383 * num_feature_args [features_args]*
1384 * num_handler_args hw_handler [hw_handler_args]*
1385 * num_groups init_group_number
1386 * [priority selector-name num_ps_args [ps_args]*
1387 * num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
1389 static int multipath_status(struct dm_target *ti, status_type_t type,
1390 char *result, unsigned int maxlen)
1393 unsigned long flags;
1394 struct multipath *m = (struct multipath *) ti->private;
1395 struct priority_group *pg;
1400 spin_lock_irqsave(&m->lock, flags);
1403 if (type == STATUSTYPE_INFO)
1404 DMEMIT("2 %u %u ", m->queue_size, m->pg_init_count);
1406 DMEMIT("%u ", m->queue_if_no_path +
1407 (m->pg_init_retries > 0) * 2);
1408 if (m->queue_if_no_path)
1409 DMEMIT("queue_if_no_path ");
1410 if (m->pg_init_retries)
1411 DMEMIT("pg_init_retries %u ", m->pg_init_retries);
1414 if (!m->hw_handler_name || type == STATUSTYPE_INFO)
1417 DMEMIT("1 %s ", m->hw_handler_name);
1419 DMEMIT("%u ", m->nr_priority_groups);
1422 pg_num = m->next_pg->pg_num;
1423 else if (m->current_pg)
1424 pg_num = m->current_pg->pg_num;
1428 DMEMIT("%u ", pg_num);
1431 case STATUSTYPE_INFO:
1432 list_for_each_entry(pg, &m->priority_groups, list) {
1434 state = 'D'; /* Disabled */
1435 else if (pg == m->current_pg)
1436 state = 'A'; /* Currently Active */
1438 state = 'E'; /* Enabled */
1440 DMEMIT("%c ", state);
1442 if (pg->ps.type->status)
1443 sz += pg->ps.type->status(&pg->ps, NULL, type,
1449 DMEMIT("%u %u ", pg->nr_pgpaths,
1450 pg->ps.type->info_args);
1452 list_for_each_entry(p, &pg->pgpaths, list) {
1453 DMEMIT("%s %s %u ", p->path.pdev,
1454 p->is_active ? "A" : "F",
1456 if (pg->ps.type->status)
1457 sz += pg->ps.type->status(&pg->ps,
1458 &p->path, type, result + sz,
1464 case STATUSTYPE_TABLE:
1465 list_for_each_entry(pg, &m->priority_groups, list) {
1466 DMEMIT("%s ", pg->ps.type->name);
1468 if (pg->ps.type->status)
1469 sz += pg->ps.type->status(&pg->ps, NULL, type,
1475 DMEMIT("%u %u ", pg->nr_pgpaths,
1476 pg->ps.type->table_args);
1478 list_for_each_entry(p, &pg->pgpaths, list) {
1479 DMEMIT("%s ", p->path.pdev);
1480 if (pg->ps.type->status)
1481 sz += pg->ps.type->status(&pg->ps,
1482 &p->path, type, result + sz,
1489 spin_unlock_irqrestore(&m->lock, flags);
1494 static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
1498 struct multipath *m = (struct multipath *) ti->private;
1502 if (!strnicmp(argv[0], MESG_STR("queue_if_no_path")))
1503 return queue_if_no_path(m, 1, 0);
1504 else if (!strnicmp(argv[0], MESG_STR("fail_if_no_path")))
1505 return queue_if_no_path(m, 0, 0);
1511 if (!strnicmp(argv[0], MESG_STR("disable_group")))
1512 return bypass_pg_num(m, argv[1], 1);
1513 else if (!strnicmp(argv[0], MESG_STR("enable_group")))
1514 return bypass_pg_num(m, argv[1], 0);
1515 else if (!strnicmp(argv[0], MESG_STR("switch_group")))
1516 return switch_pg_num(m, argv[1]);
1517 else if (!strnicmp(argv[0], MESG_STR("reinstate_path")))
1518 action = reinstate_path;
1519 else if (!strnicmp(argv[0], MESG_STR("fail_path")))
1524 r = dm_get_device(ti, argv[1], ti->begin, ti->len,
1525 dm_table_get_mode(ti->table), &dev);
1527 DMWARN("message: error getting device %s",
1532 r = action_dev(m, dev, action);
1534 dm_put_device(ti, dev);
1539 DMWARN("Unrecognised multipath message received.");
1543 static int multipath_ioctl(struct dm_target *ti, unsigned int cmd,
1546 struct multipath *m = (struct multipath *) ti->private;
1547 struct block_device *bdev = NULL;
1549 unsigned long flags;
1552 spin_lock_irqsave(&m->lock, flags);
1554 if (!m->current_pgpath)
1555 __choose_pgpath(m, 0);
1557 if (m->current_pgpath && m->current_pgpath->path.dev) {
1558 bdev = m->current_pgpath->path.dev->bdev;
1559 mode = m->current_pgpath->path.dev->mode;
1567 spin_unlock_irqrestore(&m->lock, flags);
1569 return r ? : __blkdev_driver_ioctl(bdev, mode, cmd, arg);
1572 static int multipath_iterate_devices(struct dm_target *ti,
1573 iterate_devices_callout_fn fn, void *data)
1575 struct multipath *m = ti->private;
1576 struct priority_group *pg;
1580 list_for_each_entry(pg, &m->priority_groups, list) {
1581 list_for_each_entry(p, &pg->pgpaths, list) {
1582 ret = fn(ti, p->path.dev, ti->begin, ti->len, data);
1592 static int __pgpath_busy(struct pgpath *pgpath)
1594 struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
1596 return dm_underlying_device_busy(q);
1600 * We return "busy", only when we can map I/Os but underlying devices
1601 * are busy (so even if we map I/Os now, the I/Os will wait on
1602 * the underlying queue).
1603 * In other words, if we want to kill I/Os or queue them inside us
1604 * due to map unavailability, we don't return "busy". Otherwise,
1605 * dm core won't give us the I/Os and we can't do what we want.
1607 static int multipath_busy(struct dm_target *ti)
1609 int busy = 0, has_active = 0;
1610 struct multipath *m = ti->private;
1611 struct priority_group *pg;
1612 struct pgpath *pgpath;
1613 unsigned long flags;
1615 spin_lock_irqsave(&m->lock, flags);
1617 /* Guess which priority_group will be used at next mapping time */
1618 if (unlikely(!m->current_pgpath && m->next_pg))
1620 else if (likely(m->current_pg))
1624 * We don't know which pg will be used at next mapping time.
1625 * We don't call __choose_pgpath() here to avoid to trigger
1626 * pg_init just by busy checking.
1627 * So we don't know whether underlying devices we will be using
1628 * at next mapping time are busy or not. Just try mapping.
1633 * If there is one non-busy active path at least, the path selector
1634 * will be able to select it. So we consider such a pg as not busy.
1637 list_for_each_entry(pgpath, &pg->pgpaths, list)
1638 if (pgpath->is_active) {
1641 if (!__pgpath_busy(pgpath)) {
1649 * No active path in this pg, so this pg won't be used and
1650 * the current_pg will be changed at next mapping time.
1651 * We need to try mapping to determine it.
1656 spin_unlock_irqrestore(&m->lock, flags);
1661 /*-----------------------------------------------------------------
1663 *---------------------------------------------------------------*/
1664 static struct target_type multipath_target = {
1665 .name = "multipath",
1666 .version = {1, 1, 0},
1667 .module = THIS_MODULE,
1668 .ctr = multipath_ctr,
1669 .dtr = multipath_dtr,
1670 .map_rq = multipath_map,
1671 .rq_end_io = multipath_end_io,
1672 .presuspend = multipath_presuspend,
1673 .resume = multipath_resume,
1674 .status = multipath_status,
1675 .message = multipath_message,
1676 .ioctl = multipath_ioctl,
1677 .iterate_devices = multipath_iterate_devices,
1678 .busy = multipath_busy,
1681 static int __init dm_multipath_init(void)
1685 /* allocate a slab for the dm_ios */
1686 _mpio_cache = KMEM_CACHE(dm_mpath_io, 0);
1690 r = dm_register_target(&multipath_target);
1692 DMERR("register failed %d", r);
1693 kmem_cache_destroy(_mpio_cache);
1697 kmultipathd = create_workqueue("kmpathd");
1699 DMERR("failed to create workqueue kmpathd");
1700 dm_unregister_target(&multipath_target);
1701 kmem_cache_destroy(_mpio_cache);
1706 * A separate workqueue is used to handle the device handlers
1707 * to avoid overloading existing workqueue. Overloading the
1708 * old workqueue would also create a bottleneck in the
1709 * path of the storage hardware device activation.
1711 kmpath_handlerd = create_singlethread_workqueue("kmpath_handlerd");
1712 if (!kmpath_handlerd) {
1713 DMERR("failed to create workqueue kmpath_handlerd");
1714 destroy_workqueue(kmultipathd);
1715 dm_unregister_target(&multipath_target);
1716 kmem_cache_destroy(_mpio_cache);
1720 DMINFO("version %u.%u.%u loaded",
1721 multipath_target.version[0], multipath_target.version[1],
1722 multipath_target.version[2]);
1727 static void __exit dm_multipath_exit(void)
1729 destroy_workqueue(kmpath_handlerd);
1730 destroy_workqueue(kmultipathd);
1732 dm_unregister_target(&multipath_target);
1733 kmem_cache_destroy(_mpio_cache);
1736 module_init(dm_multipath_init);
1737 module_exit(dm_multipath_exit);
1739 MODULE_DESCRIPTION(DM_NAME " multipath target");
1740 MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
1741 MODULE_LICENSE("GPL");