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 <asm/atomic.h>
24 #define DM_MSG_PREFIX "multipath"
25 #define MESG_STR(x) x, sizeof(x)
29 struct list_head list;
31 struct priority_group *pg; /* Owning PG */
32 unsigned is_active; /* Path status */
33 unsigned fail_count; /* Cumulative failure count */
36 struct work_struct activate_path;
39 #define path_to_pgpath(__pgp) container_of((__pgp), struct pgpath, path)
42 * Paths are grouped into Priority Groups and numbered from 1 upwards.
43 * Each has a path selector which controls which path gets used.
45 struct priority_group {
46 struct list_head list;
48 struct multipath *m; /* Owning multipath instance */
49 struct path_selector ps;
51 unsigned pg_num; /* Reference number */
52 unsigned bypassed; /* Temporarily bypass this PG? */
54 unsigned nr_pgpaths; /* Number of paths in PG */
55 struct list_head pgpaths;
58 /* Multipath context */
60 struct list_head list;
65 const char *hw_handler_name;
66 char *hw_handler_params;
67 unsigned nr_priority_groups;
68 struct list_head priority_groups;
69 unsigned pg_init_required; /* pg_init needs calling? */
70 unsigned pg_init_in_progress; /* Only one pg_init allowed at once */
71 wait_queue_head_t pg_init_wait; /* Wait for pg_init completion */
73 unsigned nr_valid_paths; /* Total number of usable paths */
74 struct pgpath *current_pgpath;
75 struct priority_group *current_pg;
76 struct priority_group *next_pg; /* Switch to this PG if set */
77 unsigned repeat_count; /* I/Os left before calling PS again */
79 unsigned queue_io; /* Must we queue all I/O? */
80 unsigned queue_if_no_path; /* Queue I/O if last path fails? */
81 unsigned saved_queue_if_no_path;/* Saved state during suspension */
82 unsigned pg_init_retries; /* Number of times to retry pg_init */
83 unsigned pg_init_count; /* Number of times pg_init called */
85 struct work_struct process_queued_ios;
86 struct list_head queued_ios;
89 struct work_struct trigger_event;
92 * We must use a mempool of dm_mpath_io structs so that we
93 * can resubmit bios on error.
97 struct mutex work_mutex;
101 * Context information attached to each bio we process.
104 struct pgpath *pgpath;
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);
120 /*-----------------------------------------------
121 * Allocation routines
122 *-----------------------------------------------*/
124 static struct pgpath *alloc_pgpath(void)
126 struct pgpath *pgpath = kzalloc(sizeof(*pgpath), GFP_KERNEL);
129 pgpath->is_active = 1;
130 INIT_WORK(&pgpath->activate_path, activate_path);
136 static void free_pgpath(struct pgpath *pgpath)
141 static struct priority_group *alloc_priority_group(void)
143 struct priority_group *pg;
145 pg = kzalloc(sizeof(*pg), GFP_KERNEL);
148 INIT_LIST_HEAD(&pg->pgpaths);
153 static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti)
155 struct pgpath *pgpath, *tmp;
156 struct multipath *m = ti->private;
158 list_for_each_entry_safe(pgpath, tmp, pgpaths, list) {
159 list_del(&pgpath->list);
160 if (m->hw_handler_name)
161 scsi_dh_detach(bdev_get_queue(pgpath->path.dev->bdev));
162 dm_put_device(ti, pgpath->path.dev);
167 static void free_priority_group(struct priority_group *pg,
168 struct dm_target *ti)
170 struct path_selector *ps = &pg->ps;
173 ps->type->destroy(ps);
174 dm_put_path_selector(ps->type);
177 free_pgpaths(&pg->pgpaths, ti);
181 static struct multipath *alloc_multipath(struct dm_target *ti)
185 m = kzalloc(sizeof(*m), GFP_KERNEL);
187 INIT_LIST_HEAD(&m->priority_groups);
188 INIT_LIST_HEAD(&m->queued_ios);
189 spin_lock_init(&m->lock);
191 INIT_WORK(&m->process_queued_ios, process_queued_ios);
192 INIT_WORK(&m->trigger_event, trigger_event);
193 init_waitqueue_head(&m->pg_init_wait);
194 mutex_init(&m->work_mutex);
195 m->mpio_pool = mempool_create_slab_pool(MIN_IOS, _mpio_cache);
207 static void free_multipath(struct multipath *m)
209 struct priority_group *pg, *tmp;
211 list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) {
213 free_priority_group(pg, m->ti);
216 kfree(m->hw_handler_name);
217 kfree(m->hw_handler_params);
218 mempool_destroy(m->mpio_pool);
223 /*-----------------------------------------------
225 *-----------------------------------------------*/
227 static void __pg_init_all_paths(struct multipath *m)
229 struct pgpath *pgpath;
232 m->pg_init_required = 0;
233 list_for_each_entry(pgpath, &m->current_pg->pgpaths, list) {
234 /* Skip failed paths */
235 if (!pgpath->is_active)
237 if (queue_work(kmpath_handlerd, &pgpath->activate_path))
238 m->pg_init_in_progress++;
242 static void __switch_pg(struct multipath *m, struct pgpath *pgpath)
244 m->current_pg = pgpath->pg;
246 /* Must we initialise the PG first, and queue I/O till it's ready? */
247 if (m->hw_handler_name) {
248 m->pg_init_required = 1;
251 m->pg_init_required = 0;
255 m->pg_init_count = 0;
258 static int __choose_path_in_pg(struct multipath *m, struct priority_group *pg,
261 struct dm_path *path;
263 path = pg->ps.type->select_path(&pg->ps, &m->repeat_count, nr_bytes);
267 m->current_pgpath = path_to_pgpath(path);
269 if (m->current_pg != pg)
270 __switch_pg(m, m->current_pgpath);
275 static void __choose_pgpath(struct multipath *m, size_t nr_bytes)
277 struct priority_group *pg;
278 unsigned bypassed = 1;
280 if (!m->nr_valid_paths)
283 /* Were we instructed to switch PG? */
287 if (!__choose_path_in_pg(m, pg, nr_bytes))
291 /* Don't change PG until it has no remaining paths */
292 if (m->current_pg && !__choose_path_in_pg(m, m->current_pg, nr_bytes))
296 * Loop through priority groups until we find a valid path.
297 * First time we skip PGs marked 'bypassed'.
298 * Second time we only try the ones we skipped.
301 list_for_each_entry(pg, &m->priority_groups, list) {
302 if (pg->bypassed == bypassed)
304 if (!__choose_path_in_pg(m, pg, nr_bytes))
307 } while (bypassed--);
310 m->current_pgpath = NULL;
311 m->current_pg = NULL;
315 * Check whether bios must be queued in the device-mapper core rather
316 * than here in the target.
318 * m->lock must be held on entry.
320 * If m->queue_if_no_path and m->saved_queue_if_no_path hold the
321 * same value then we are not between multipath_presuspend()
322 * and multipath_resume() calls and we have no need to check
323 * for the DMF_NOFLUSH_SUSPENDING flag.
325 static int __must_push_back(struct multipath *m)
327 return (m->queue_if_no_path != m->saved_queue_if_no_path &&
328 dm_noflush_suspending(m->ti));
331 static int map_io(struct multipath *m, struct request *clone,
332 struct dm_mpath_io *mpio, unsigned was_queued)
334 int r = DM_MAPIO_REMAPPED;
335 size_t nr_bytes = blk_rq_bytes(clone);
337 struct pgpath *pgpath;
338 struct block_device *bdev;
340 spin_lock_irqsave(&m->lock, flags);
342 /* Do we need to select a new pgpath? */
343 if (!m->current_pgpath ||
344 (!m->queue_io && (m->repeat_count && --m->repeat_count == 0)))
345 __choose_pgpath(m, nr_bytes);
347 pgpath = m->current_pgpath;
352 if ((pgpath && m->queue_io) ||
353 (!pgpath && m->queue_if_no_path)) {
354 /* Queue for the daemon to resubmit */
355 list_add_tail(&clone->queuelist, &m->queued_ios);
357 if ((m->pg_init_required && !m->pg_init_in_progress) ||
359 queue_work(kmultipathd, &m->process_queued_ios);
361 r = DM_MAPIO_SUBMITTED;
363 bdev = pgpath->path.dev->bdev;
364 clone->q = bdev_get_queue(bdev);
365 clone->rq_disk = bdev->bd_disk;
366 } else if (__must_push_back(m))
367 r = DM_MAPIO_REQUEUE;
369 r = -EIO; /* Failed */
371 mpio->pgpath = pgpath;
372 mpio->nr_bytes = nr_bytes;
374 if (r == DM_MAPIO_REMAPPED && pgpath->pg->ps.type->start_io)
375 pgpath->pg->ps.type->start_io(&pgpath->pg->ps, &pgpath->path,
378 spin_unlock_irqrestore(&m->lock, flags);
384 * If we run out of usable paths, should we queue I/O or error it?
386 static int queue_if_no_path(struct multipath *m, unsigned queue_if_no_path,
387 unsigned save_old_value)
391 spin_lock_irqsave(&m->lock, flags);
394 m->saved_queue_if_no_path = m->queue_if_no_path;
396 m->saved_queue_if_no_path = queue_if_no_path;
397 m->queue_if_no_path = queue_if_no_path;
398 if (!m->queue_if_no_path && m->queue_size)
399 queue_work(kmultipathd, &m->process_queued_ios);
401 spin_unlock_irqrestore(&m->lock, flags);
406 /*-----------------------------------------------------------------
407 * The multipath daemon is responsible for resubmitting queued ios.
408 *---------------------------------------------------------------*/
410 static void dispatch_queued_ios(struct multipath *m)
414 struct dm_mpath_io *mpio;
415 union map_info *info;
416 struct request *clone, *n;
419 spin_lock_irqsave(&m->lock, flags);
420 list_splice_init(&m->queued_ios, &cl);
421 spin_unlock_irqrestore(&m->lock, flags);
423 list_for_each_entry_safe(clone, n, &cl, queuelist) {
424 list_del_init(&clone->queuelist);
426 info = dm_get_rq_mapinfo(clone);
429 r = map_io(m, clone, mpio, 1);
431 mempool_free(mpio, m->mpio_pool);
432 dm_kill_unmapped_request(clone, r);
433 } else if (r == DM_MAPIO_REMAPPED)
434 dm_dispatch_request(clone);
435 else if (r == DM_MAPIO_REQUEUE) {
436 mempool_free(mpio, m->mpio_pool);
437 dm_requeue_unmapped_request(clone);
442 static void process_queued_ios(struct work_struct *work)
444 struct multipath *m =
445 container_of(work, struct multipath, process_queued_ios);
446 struct pgpath *pgpath = NULL;
447 unsigned must_queue = 1;
450 spin_lock_irqsave(&m->lock, flags);
455 if (!m->current_pgpath)
456 __choose_pgpath(m, 0);
458 pgpath = m->current_pgpath;
460 if ((pgpath && !m->queue_io) ||
461 (!pgpath && !m->queue_if_no_path))
464 if (m->pg_init_required && !m->pg_init_in_progress && pgpath)
465 __pg_init_all_paths(m);
468 spin_unlock_irqrestore(&m->lock, flags);
470 dispatch_queued_ios(m);
474 * An event is triggered whenever a path is taken out of use.
475 * Includes path failure and PG bypass.
477 static void trigger_event(struct work_struct *work)
479 struct multipath *m =
480 container_of(work, struct multipath, trigger_event);
482 dm_table_event(m->ti->table);
485 /*-----------------------------------------------------------------
486 * Constructor/argument parsing:
487 * <#multipath feature args> [<arg>]*
488 * <#hw_handler args> [hw_handler [<arg>]*]
490 * <initial priority group>
491 * [<selector> <#selector args> [<arg>]*
492 * <#paths> <#per-path selector args>
493 * [<path> [<arg>]* ]+ ]+
494 *---------------------------------------------------------------*/
501 static int read_param(struct param *param, char *str, unsigned *v, char **error)
504 (sscanf(str, "%u", v) != 1) ||
507 *error = param->error;
519 static char *shift(struct arg_set *as)
533 static void consume(struct arg_set *as, unsigned n)
535 BUG_ON (as->argc < n);
540 static int parse_path_selector(struct arg_set *as, struct priority_group *pg,
541 struct dm_target *ti)
544 struct path_selector_type *pst;
547 static struct param _params[] = {
548 {0, 1024, "invalid number of path selector args"},
551 pst = dm_get_path_selector(shift(as));
553 ti->error = "unknown path selector type";
557 r = read_param(_params, shift(as), &ps_argc, &ti->error);
559 dm_put_path_selector(pst);
563 if (ps_argc > as->argc) {
564 dm_put_path_selector(pst);
565 ti->error = "not enough arguments for path selector";
569 r = pst->create(&pg->ps, ps_argc, as->argv);
571 dm_put_path_selector(pst);
572 ti->error = "path selector constructor failed";
577 consume(as, ps_argc);
582 static struct pgpath *parse_path(struct arg_set *as, struct path_selector *ps,
583 struct dm_target *ti)
587 struct multipath *m = ti->private;
589 /* we need at least a path arg */
591 ti->error = "no device given";
592 return ERR_PTR(-EINVAL);
597 return ERR_PTR(-ENOMEM);
599 r = dm_get_device(ti, shift(as), dm_table_get_mode(ti->table),
602 ti->error = "error getting device";
606 if (m->hw_handler_name) {
607 struct request_queue *q = bdev_get_queue(p->path.dev->bdev);
609 r = scsi_dh_attach(q, m->hw_handler_name);
612 * Already attached to different hw_handler,
613 * try to reattach with correct one.
616 r = scsi_dh_attach(q, m->hw_handler_name);
620 ti->error = "error attaching hardware handler";
621 dm_put_device(ti, p->path.dev);
625 if (m->hw_handler_params) {
626 r = scsi_dh_set_params(q, m->hw_handler_params);
628 ti->error = "unable to set hardware "
629 "handler parameters";
631 dm_put_device(ti, p->path.dev);
637 r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
639 dm_put_device(ti, p->path.dev);
650 static struct priority_group *parse_priority_group(struct arg_set *as,
653 static struct param _params[] = {
654 {1, 1024, "invalid number of paths"},
655 {0, 1024, "invalid number of selector args"}
659 unsigned i, nr_selector_args, nr_params;
660 struct priority_group *pg;
661 struct dm_target *ti = m->ti;
665 ti->error = "not enough priority group arguments";
666 return ERR_PTR(-EINVAL);
669 pg = alloc_priority_group();
671 ti->error = "couldn't allocate priority group";
672 return ERR_PTR(-ENOMEM);
676 r = parse_path_selector(as, pg, ti);
683 r = read_param(_params, shift(as), &pg->nr_pgpaths, &ti->error);
687 r = read_param(_params + 1, shift(as), &nr_selector_args, &ti->error);
691 nr_params = 1 + nr_selector_args;
692 for (i = 0; i < pg->nr_pgpaths; i++) {
693 struct pgpath *pgpath;
694 struct arg_set path_args;
696 if (as->argc < nr_params) {
697 ti->error = "not enough path parameters";
702 path_args.argc = nr_params;
703 path_args.argv = as->argv;
705 pgpath = parse_path(&path_args, &pg->ps, ti);
706 if (IS_ERR(pgpath)) {
712 list_add_tail(&pgpath->list, &pg->pgpaths);
713 consume(as, nr_params);
719 free_priority_group(pg, ti);
723 static int parse_hw_handler(struct arg_set *as, struct multipath *m)
727 struct dm_target *ti = m->ti;
729 static struct param _params[] = {
730 {0, 1024, "invalid number of hardware handler args"},
733 if (read_param(_params, shift(as), &hw_argc, &ti->error))
739 if (hw_argc > as->argc) {
740 ti->error = "not enough arguments for hardware handler";
744 m->hw_handler_name = kstrdup(shift(as), GFP_KERNEL);
745 request_module("scsi_dh_%s", m->hw_handler_name);
746 if (scsi_dh_handler_exist(m->hw_handler_name) == 0) {
747 ti->error = "unknown hardware handler type";
756 for (i = 0; i <= hw_argc - 2; i++)
757 len += strlen(as->argv[i]) + 1;
758 p = m->hw_handler_params = kzalloc(len, GFP_KERNEL);
760 ti->error = "memory allocation failed";
764 j = sprintf(p, "%d", hw_argc - 1);
765 for (i = 0, p+=j+1; i <= hw_argc - 2; i++, p+=j+1)
766 j = sprintf(p, "%s", as->argv[i]);
768 consume(as, hw_argc - 1);
772 kfree(m->hw_handler_name);
773 m->hw_handler_name = NULL;
777 static int parse_features(struct arg_set *as, struct multipath *m)
781 struct dm_target *ti = m->ti;
782 const char *param_name;
784 static struct param _params[] = {
785 {0, 3, "invalid number of feature args"},
786 {1, 50, "pg_init_retries must be between 1 and 50"},
789 r = read_param(_params, shift(as), &argc, &ti->error);
797 param_name = shift(as);
800 if (!strnicmp(param_name, MESG_STR("queue_if_no_path"))) {
801 r = queue_if_no_path(m, 1, 0);
805 if (!strnicmp(param_name, MESG_STR("pg_init_retries")) &&
807 r = read_param(_params + 1, shift(as),
808 &m->pg_init_retries, &ti->error);
813 ti->error = "Unrecognised multipath feature request";
815 } while (argc && !r);
820 static int multipath_ctr(struct dm_target *ti, unsigned int argc,
823 /* target parameters */
824 static struct param _params[] = {
825 {1, 1024, "invalid number of priority groups"},
826 {1, 1024, "invalid initial priority group number"},
832 unsigned pg_count = 0;
833 unsigned next_pg_num;
838 m = alloc_multipath(ti);
840 ti->error = "can't allocate multipath";
844 r = parse_features(&as, m);
848 r = parse_hw_handler(&as, m);
852 r = read_param(_params, shift(&as), &m->nr_priority_groups, &ti->error);
856 r = read_param(_params + 1, shift(&as), &next_pg_num, &ti->error);
860 /* parse the priority groups */
862 struct priority_group *pg;
864 pg = parse_priority_group(&as, m);
870 m->nr_valid_paths += pg->nr_pgpaths;
871 list_add_tail(&pg->list, &m->priority_groups);
873 pg->pg_num = pg_count;
878 if (pg_count != m->nr_priority_groups) {
879 ti->error = "priority group count mismatch";
884 ti->num_flush_requests = 1;
885 ti->num_discard_requests = 1;
894 static void multipath_wait_for_pg_init_completion(struct multipath *m)
896 DECLARE_WAITQUEUE(wait, current);
899 add_wait_queue(&m->pg_init_wait, &wait);
902 set_current_state(TASK_UNINTERRUPTIBLE);
904 spin_lock_irqsave(&m->lock, flags);
905 if (!m->pg_init_in_progress) {
906 spin_unlock_irqrestore(&m->lock, flags);
909 spin_unlock_irqrestore(&m->lock, flags);
913 set_current_state(TASK_RUNNING);
915 remove_wait_queue(&m->pg_init_wait, &wait);
918 static void flush_multipath_work(struct multipath *m)
920 flush_workqueue(kmpath_handlerd);
921 multipath_wait_for_pg_init_completion(m);
922 flush_workqueue(kmultipathd);
923 flush_scheduled_work();
926 static void multipath_dtr(struct dm_target *ti)
928 struct multipath *m = ti->private;
930 flush_multipath_work(m);
935 * Map cloned requests
937 static int multipath_map(struct dm_target *ti, struct request *clone,
938 union map_info *map_context)
941 struct dm_mpath_io *mpio;
942 struct multipath *m = (struct multipath *) ti->private;
944 mpio = mempool_alloc(m->mpio_pool, GFP_ATOMIC);
946 /* ENOMEM, requeue */
947 return DM_MAPIO_REQUEUE;
948 memset(mpio, 0, sizeof(*mpio));
950 map_context->ptr = mpio;
951 clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
952 r = map_io(m, clone, mpio, 0);
953 if (r < 0 || r == DM_MAPIO_REQUEUE)
954 mempool_free(mpio, m->mpio_pool);
960 * Take a path out of use.
962 static int fail_path(struct pgpath *pgpath)
965 struct multipath *m = pgpath->pg->m;
967 spin_lock_irqsave(&m->lock, flags);
969 if (!pgpath->is_active)
972 DMWARN("Failing path %s.", pgpath->path.dev->name);
974 pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
975 pgpath->is_active = 0;
976 pgpath->fail_count++;
980 if (pgpath == m->current_pgpath)
981 m->current_pgpath = NULL;
983 dm_path_uevent(DM_UEVENT_PATH_FAILED, m->ti,
984 pgpath->path.dev->name, m->nr_valid_paths);
986 schedule_work(&m->trigger_event);
989 spin_unlock_irqrestore(&m->lock, flags);
995 * Reinstate a previously-failed path
997 static int reinstate_path(struct pgpath *pgpath)
1000 unsigned long flags;
1001 struct multipath *m = pgpath->pg->m;
1003 spin_lock_irqsave(&m->lock, flags);
1005 if (pgpath->is_active)
1008 if (!pgpath->pg->ps.type->reinstate_path) {
1009 DMWARN("Reinstate path not supported by path selector %s",
1010 pgpath->pg->ps.type->name);
1015 r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
1019 pgpath->is_active = 1;
1021 if (!m->nr_valid_paths++ && m->queue_size) {
1022 m->current_pgpath = NULL;
1023 queue_work(kmultipathd, &m->process_queued_ios);
1024 } else if (m->hw_handler_name && (m->current_pg == pgpath->pg)) {
1025 if (queue_work(kmpath_handlerd, &pgpath->activate_path))
1026 m->pg_init_in_progress++;
1029 dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti,
1030 pgpath->path.dev->name, m->nr_valid_paths);
1032 schedule_work(&m->trigger_event);
1035 spin_unlock_irqrestore(&m->lock, flags);
1041 * Fail or reinstate all paths that match the provided struct dm_dev.
1043 static int action_dev(struct multipath *m, struct dm_dev *dev,
1047 struct pgpath *pgpath;
1048 struct priority_group *pg;
1050 list_for_each_entry(pg, &m->priority_groups, list) {
1051 list_for_each_entry(pgpath, &pg->pgpaths, list) {
1052 if (pgpath->path.dev == dev)
1061 * Temporarily try to avoid having to use the specified PG
1063 static void bypass_pg(struct multipath *m, struct priority_group *pg,
1066 unsigned long flags;
1068 spin_lock_irqsave(&m->lock, flags);
1070 pg->bypassed = bypassed;
1071 m->current_pgpath = NULL;
1072 m->current_pg = NULL;
1074 spin_unlock_irqrestore(&m->lock, flags);
1076 schedule_work(&m->trigger_event);
1080 * Switch to using the specified PG from the next I/O that gets mapped
1082 static int switch_pg_num(struct multipath *m, const char *pgstr)
1084 struct priority_group *pg;
1086 unsigned long flags;
1088 if (!pgstr || (sscanf(pgstr, "%u", &pgnum) != 1) || !pgnum ||
1089 (pgnum > m->nr_priority_groups)) {
1090 DMWARN("invalid PG number supplied to switch_pg_num");
1094 spin_lock_irqsave(&m->lock, flags);
1095 list_for_each_entry(pg, &m->priority_groups, list) {
1100 m->current_pgpath = NULL;
1101 m->current_pg = NULL;
1104 spin_unlock_irqrestore(&m->lock, flags);
1106 schedule_work(&m->trigger_event);
1111 * Set/clear bypassed status of a PG.
1112 * PGs are numbered upwards from 1 in the order they were declared.
1114 static int bypass_pg_num(struct multipath *m, const char *pgstr, int bypassed)
1116 struct priority_group *pg;
1119 if (!pgstr || (sscanf(pgstr, "%u", &pgnum) != 1) || !pgnum ||
1120 (pgnum > m->nr_priority_groups)) {
1121 DMWARN("invalid PG number supplied to bypass_pg");
1125 list_for_each_entry(pg, &m->priority_groups, list) {
1130 bypass_pg(m, pg, bypassed);
1135 * Should we retry pg_init immediately?
1137 static int pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath)
1139 unsigned long flags;
1140 int limit_reached = 0;
1142 spin_lock_irqsave(&m->lock, flags);
1144 if (m->pg_init_count <= m->pg_init_retries)
1145 m->pg_init_required = 1;
1149 spin_unlock_irqrestore(&m->lock, flags);
1151 return limit_reached;
1154 static void pg_init_done(void *data, int errors)
1156 struct pgpath *pgpath = data;
1157 struct priority_group *pg = pgpath->pg;
1158 struct multipath *m = pg->m;
1159 unsigned long flags;
1161 /* device or driver problems */
1166 if (!m->hw_handler_name) {
1170 DMERR("Could not failover the device: Handler scsi_dh_%s "
1171 "Error %d.", m->hw_handler_name, errors);
1173 * Fail path for now, so we do not ping pong
1177 case SCSI_DH_DEV_TEMP_BUSY:
1179 * Probably doing something like FW upgrade on the
1180 * controller so try the other pg.
1182 bypass_pg(m, pg, 1);
1184 /* TODO: For SCSI_DH_RETRY we should wait a couple seconds */
1186 case SCSI_DH_IMM_RETRY:
1187 case SCSI_DH_RES_TEMP_UNAVAIL:
1188 if (pg_init_limit_reached(m, pgpath))
1194 * We probably do not want to fail the path for a device
1195 * error, but this is what the old dm did. In future
1196 * patches we can do more advanced handling.
1201 spin_lock_irqsave(&m->lock, flags);
1203 if (pgpath == m->current_pgpath) {
1204 DMERR("Could not failover device. Error %d.", errors);
1205 m->current_pgpath = NULL;
1206 m->current_pg = NULL;
1208 } else if (!m->pg_init_required)
1211 if (--m->pg_init_in_progress)
1212 /* Activations of other paths are still on going */
1215 if (!m->pg_init_required)
1218 queue_work(kmultipathd, &m->process_queued_ios);
1221 * Wake up any thread waiting to suspend.
1223 wake_up(&m->pg_init_wait);
1226 spin_unlock_irqrestore(&m->lock, flags);
1229 static void activate_path(struct work_struct *work)
1231 struct pgpath *pgpath =
1232 container_of(work, struct pgpath, activate_path);
1234 scsi_dh_activate(bdev_get_queue(pgpath->path.dev->bdev),
1235 pg_init_done, pgpath);
1241 static int do_end_io(struct multipath *m, struct request *clone,
1242 int error, struct dm_mpath_io *mpio)
1245 * We don't queue any clone request inside the multipath target
1246 * during end I/O handling, since those clone requests don't have
1247 * bio clones. If we queue them inside the multipath target,
1248 * we need to make bio clones, that requires memory allocation.
1249 * (See drivers/md/dm.c:end_clone_bio() about why the clone requests
1250 * don't have bio clones.)
1251 * Instead of queueing the clone request here, we queue the original
1252 * request into dm core, which will remake a clone request and
1253 * clone bios for it and resubmit it later.
1255 int r = DM_ENDIO_REQUEUE;
1256 unsigned long flags;
1258 if (!error && !clone->errors)
1259 return 0; /* I/O complete */
1261 if (error == -EOPNOTSUPP)
1264 if (clone->cmd_flags & REQ_DISCARD)
1266 * Pass all discard request failures up.
1267 * FIXME: only fail_path if the discard failed due to a
1268 * transport problem. This requires precise understanding
1269 * of the underlying failure (e.g. the SCSI sense).
1274 fail_path(mpio->pgpath);
1276 spin_lock_irqsave(&m->lock, flags);
1277 if (!m->nr_valid_paths && !m->queue_if_no_path && !__must_push_back(m))
1279 spin_unlock_irqrestore(&m->lock, flags);
1284 static int multipath_end_io(struct dm_target *ti, struct request *clone,
1285 int error, union map_info *map_context)
1287 struct multipath *m = ti->private;
1288 struct dm_mpath_io *mpio = map_context->ptr;
1289 struct pgpath *pgpath = mpio->pgpath;
1290 struct path_selector *ps;
1293 r = do_end_io(m, clone, error, mpio);
1295 ps = &pgpath->pg->ps;
1296 if (ps->type->end_io)
1297 ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
1299 mempool_free(mpio, m->mpio_pool);
1305 * Suspend can't complete until all the I/O is processed so if
1306 * the last path fails we must error any remaining I/O.
1307 * Note that if the freeze_bdev fails while suspending, the
1308 * queue_if_no_path state is lost - userspace should reset it.
1310 static void multipath_presuspend(struct dm_target *ti)
1312 struct multipath *m = (struct multipath *) ti->private;
1314 queue_if_no_path(m, 0, 1);
1317 static void multipath_postsuspend(struct dm_target *ti)
1319 struct multipath *m = ti->private;
1321 mutex_lock(&m->work_mutex);
1322 flush_multipath_work(m);
1323 mutex_unlock(&m->work_mutex);
1327 * Restore the queue_if_no_path setting.
1329 static void multipath_resume(struct dm_target *ti)
1331 struct multipath *m = (struct multipath *) ti->private;
1332 unsigned long flags;
1334 spin_lock_irqsave(&m->lock, flags);
1335 m->queue_if_no_path = m->saved_queue_if_no_path;
1336 spin_unlock_irqrestore(&m->lock, flags);
1340 * Info output has the following format:
1341 * num_multipath_feature_args [multipath_feature_args]*
1342 * num_handler_status_args [handler_status_args]*
1343 * num_groups init_group_number
1344 * [A|D|E num_ps_status_args [ps_status_args]*
1345 * num_paths num_selector_args
1346 * [path_dev A|F fail_count [selector_args]* ]+ ]+
1348 * Table output has the following format (identical to the constructor string):
1349 * num_feature_args [features_args]*
1350 * num_handler_args hw_handler [hw_handler_args]*
1351 * num_groups init_group_number
1352 * [priority selector-name num_ps_args [ps_args]*
1353 * num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
1355 static int multipath_status(struct dm_target *ti, status_type_t type,
1356 char *result, unsigned int maxlen)
1359 unsigned long flags;
1360 struct multipath *m = (struct multipath *) ti->private;
1361 struct priority_group *pg;
1366 spin_lock_irqsave(&m->lock, flags);
1369 if (type == STATUSTYPE_INFO)
1370 DMEMIT("2 %u %u ", m->queue_size, m->pg_init_count);
1372 DMEMIT("%u ", m->queue_if_no_path +
1373 (m->pg_init_retries > 0) * 2);
1374 if (m->queue_if_no_path)
1375 DMEMIT("queue_if_no_path ");
1376 if (m->pg_init_retries)
1377 DMEMIT("pg_init_retries %u ", m->pg_init_retries);
1380 if (!m->hw_handler_name || type == STATUSTYPE_INFO)
1383 DMEMIT("1 %s ", m->hw_handler_name);
1385 DMEMIT("%u ", m->nr_priority_groups);
1388 pg_num = m->next_pg->pg_num;
1389 else if (m->current_pg)
1390 pg_num = m->current_pg->pg_num;
1394 DMEMIT("%u ", pg_num);
1397 case STATUSTYPE_INFO:
1398 list_for_each_entry(pg, &m->priority_groups, list) {
1400 state = 'D'; /* Disabled */
1401 else if (pg == m->current_pg)
1402 state = 'A'; /* Currently Active */
1404 state = 'E'; /* Enabled */
1406 DMEMIT("%c ", state);
1408 if (pg->ps.type->status)
1409 sz += pg->ps.type->status(&pg->ps, NULL, type,
1415 DMEMIT("%u %u ", pg->nr_pgpaths,
1416 pg->ps.type->info_args);
1418 list_for_each_entry(p, &pg->pgpaths, list) {
1419 DMEMIT("%s %s %u ", p->path.dev->name,
1420 p->is_active ? "A" : "F",
1422 if (pg->ps.type->status)
1423 sz += pg->ps.type->status(&pg->ps,
1424 &p->path, type, result + sz,
1430 case STATUSTYPE_TABLE:
1431 list_for_each_entry(pg, &m->priority_groups, list) {
1432 DMEMIT("%s ", pg->ps.type->name);
1434 if (pg->ps.type->status)
1435 sz += pg->ps.type->status(&pg->ps, NULL, type,
1441 DMEMIT("%u %u ", pg->nr_pgpaths,
1442 pg->ps.type->table_args);
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,
1455 spin_unlock_irqrestore(&m->lock, flags);
1460 static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
1464 struct multipath *m = (struct multipath *) ti->private;
1467 mutex_lock(&m->work_mutex);
1469 if (dm_suspended(ti)) {
1475 if (!strnicmp(argv[0], MESG_STR("queue_if_no_path"))) {
1476 r = queue_if_no_path(m, 1, 0);
1478 } else if (!strnicmp(argv[0], MESG_STR("fail_if_no_path"))) {
1479 r = queue_if_no_path(m, 0, 0);
1485 DMWARN("Unrecognised multipath message received.");
1489 if (!strnicmp(argv[0], MESG_STR("disable_group"))) {
1490 r = bypass_pg_num(m, argv[1], 1);
1492 } else if (!strnicmp(argv[0], MESG_STR("enable_group"))) {
1493 r = bypass_pg_num(m, argv[1], 0);
1495 } else if (!strnicmp(argv[0], MESG_STR("switch_group"))) {
1496 r = switch_pg_num(m, argv[1]);
1498 } else if (!strnicmp(argv[0], MESG_STR("reinstate_path")))
1499 action = reinstate_path;
1500 else if (!strnicmp(argv[0], MESG_STR("fail_path")))
1503 DMWARN("Unrecognised multipath message received.");
1507 r = dm_get_device(ti, argv[1], dm_table_get_mode(ti->table), &dev);
1509 DMWARN("message: error getting device %s",
1514 r = action_dev(m, dev, action);
1516 dm_put_device(ti, dev);
1519 mutex_unlock(&m->work_mutex);
1523 static int multipath_ioctl(struct dm_target *ti, unsigned int cmd,
1526 struct multipath *m = (struct multipath *) ti->private;
1527 struct block_device *bdev = NULL;
1529 unsigned long flags;
1532 spin_lock_irqsave(&m->lock, flags);
1534 if (!m->current_pgpath)
1535 __choose_pgpath(m, 0);
1537 if (m->current_pgpath) {
1538 bdev = m->current_pgpath->path.dev->bdev;
1539 mode = m->current_pgpath->path.dev->mode;
1547 spin_unlock_irqrestore(&m->lock, flags);
1549 return r ? : __blkdev_driver_ioctl(bdev, mode, cmd, arg);
1552 static int multipath_iterate_devices(struct dm_target *ti,
1553 iterate_devices_callout_fn fn, void *data)
1555 struct multipath *m = ti->private;
1556 struct priority_group *pg;
1560 list_for_each_entry(pg, &m->priority_groups, list) {
1561 list_for_each_entry(p, &pg->pgpaths, list) {
1562 ret = fn(ti, p->path.dev, ti->begin, ti->len, data);
1572 static int __pgpath_busy(struct pgpath *pgpath)
1574 struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
1576 return dm_underlying_device_busy(q);
1580 * We return "busy", only when we can map I/Os but underlying devices
1581 * are busy (so even if we map I/Os now, the I/Os will wait on
1582 * the underlying queue).
1583 * In other words, if we want to kill I/Os or queue them inside us
1584 * due to map unavailability, we don't return "busy". Otherwise,
1585 * dm core won't give us the I/Os and we can't do what we want.
1587 static int multipath_busy(struct dm_target *ti)
1589 int busy = 0, has_active = 0;
1590 struct multipath *m = ti->private;
1591 struct priority_group *pg;
1592 struct pgpath *pgpath;
1593 unsigned long flags;
1595 spin_lock_irqsave(&m->lock, flags);
1597 /* Guess which priority_group will be used at next mapping time */
1598 if (unlikely(!m->current_pgpath && m->next_pg))
1600 else if (likely(m->current_pg))
1604 * We don't know which pg will be used at next mapping time.
1605 * We don't call __choose_pgpath() here to avoid to trigger
1606 * pg_init just by busy checking.
1607 * So we don't know whether underlying devices we will be using
1608 * at next mapping time are busy or not. Just try mapping.
1613 * If there is one non-busy active path at least, the path selector
1614 * will be able to select it. So we consider such a pg as not busy.
1617 list_for_each_entry(pgpath, &pg->pgpaths, list)
1618 if (pgpath->is_active) {
1621 if (!__pgpath_busy(pgpath)) {
1629 * No active path in this pg, so this pg won't be used and
1630 * the current_pg will be changed at next mapping time.
1631 * We need to try mapping to determine it.
1636 spin_unlock_irqrestore(&m->lock, flags);
1641 /*-----------------------------------------------------------------
1643 *---------------------------------------------------------------*/
1644 static struct target_type multipath_target = {
1645 .name = "multipath",
1646 .version = {1, 1, 1},
1647 .module = THIS_MODULE,
1648 .ctr = multipath_ctr,
1649 .dtr = multipath_dtr,
1650 .map_rq = multipath_map,
1651 .rq_end_io = multipath_end_io,
1652 .presuspend = multipath_presuspend,
1653 .postsuspend = multipath_postsuspend,
1654 .resume = multipath_resume,
1655 .status = multipath_status,
1656 .message = multipath_message,
1657 .ioctl = multipath_ioctl,
1658 .iterate_devices = multipath_iterate_devices,
1659 .busy = multipath_busy,
1662 static int __init dm_multipath_init(void)
1666 /* allocate a slab for the dm_ios */
1667 _mpio_cache = KMEM_CACHE(dm_mpath_io, 0);
1671 r = dm_register_target(&multipath_target);
1673 DMERR("register failed %d", r);
1674 kmem_cache_destroy(_mpio_cache);
1678 kmultipathd = create_workqueue("kmpathd");
1680 DMERR("failed to create workqueue kmpathd");
1681 dm_unregister_target(&multipath_target);
1682 kmem_cache_destroy(_mpio_cache);
1687 * A separate workqueue is used to handle the device handlers
1688 * to avoid overloading existing workqueue. Overloading the
1689 * old workqueue would also create a bottleneck in the
1690 * path of the storage hardware device activation.
1692 kmpath_handlerd = create_singlethread_workqueue("kmpath_handlerd");
1693 if (!kmpath_handlerd) {
1694 DMERR("failed to create workqueue kmpath_handlerd");
1695 destroy_workqueue(kmultipathd);
1696 dm_unregister_target(&multipath_target);
1697 kmem_cache_destroy(_mpio_cache);
1701 DMINFO("version %u.%u.%u loaded",
1702 multipath_target.version[0], multipath_target.version[1],
1703 multipath_target.version[2]);
1708 static void __exit dm_multipath_exit(void)
1710 destroy_workqueue(kmpath_handlerd);
1711 destroy_workqueue(kmultipathd);
1713 dm_unregister_target(&multipath_target);
1714 kmem_cache_destroy(_mpio_cache);
1717 module_init(dm_multipath_init);
1718 module_exit(dm_multipath_exit);
1720 MODULE_DESCRIPTION(DM_NAME " multipath target");
1721 MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
1722 MODULE_LICENSE("GPL");