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 <linux/atomic.h>
24 #define DM_MSG_PREFIX "multipath"
25 #define MESG_STR(x) x, sizeof(x)
26 #define DM_PG_INIT_DELAY_MSECS 2000
27 #define DM_PG_INIT_DELAY_DEFAULT ((unsigned) -1)
31 struct list_head list;
33 struct priority_group *pg; /* Owning PG */
34 unsigned is_active; /* Path status */
35 unsigned fail_count; /* Cumulative failure count */
38 struct delayed_work 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;
70 unsigned nr_priority_groups;
71 struct list_head priority_groups;
73 wait_queue_head_t pg_init_wait; /* Wait for pg_init completion */
75 unsigned pg_init_required; /* pg_init needs calling? */
76 unsigned pg_init_in_progress; /* Only one pg_init allowed at once */
77 unsigned pg_init_delay_retry; /* Delay pg_init retry? */
79 unsigned nr_valid_paths; /* Total number of usable paths */
80 struct pgpath *current_pgpath;
81 struct priority_group *current_pg;
82 struct priority_group *next_pg; /* Switch to this PG if set */
83 unsigned repeat_count; /* I/Os left before calling PS again */
85 unsigned queue_io; /* Must we queue all I/O? */
86 unsigned queue_if_no_path; /* Queue I/O if last path fails? */
87 unsigned saved_queue_if_no_path;/* Saved state during suspension */
88 unsigned pg_init_retries; /* Number of times to retry pg_init */
89 unsigned pg_init_count; /* Number of times pg_init called */
90 unsigned pg_init_delay_msecs; /* Number of msecs before pg_init retry */
92 struct work_struct process_queued_ios;
93 struct list_head queued_ios;
96 struct work_struct trigger_event;
99 * We must use a mempool of dm_mpath_io structs so that we
100 * can resubmit bios on error.
102 mempool_t *mpio_pool;
104 struct mutex work_mutex;
108 * Context information attached to each bio we process.
111 struct pgpath *pgpath;
115 typedef int (*action_fn) (struct pgpath *pgpath);
117 #define MIN_IOS 256 /* Mempool size */
119 static struct kmem_cache *_mpio_cache;
121 static struct workqueue_struct *kmultipathd, *kmpath_handlerd;
122 static void process_queued_ios(struct work_struct *work);
123 static void trigger_event(struct work_struct *work);
124 static void activate_path(struct work_struct *work);
127 /*-----------------------------------------------
128 * Allocation routines
129 *-----------------------------------------------*/
131 static struct pgpath *alloc_pgpath(void)
133 struct pgpath *pgpath = kzalloc(sizeof(*pgpath), GFP_KERNEL);
136 pgpath->is_active = 1;
137 INIT_DELAYED_WORK(&pgpath->activate_path, activate_path);
143 static void free_pgpath(struct pgpath *pgpath)
148 static struct priority_group *alloc_priority_group(void)
150 struct priority_group *pg;
152 pg = kzalloc(sizeof(*pg), GFP_KERNEL);
155 INIT_LIST_HEAD(&pg->pgpaths);
160 static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti)
162 struct pgpath *pgpath, *tmp;
163 struct multipath *m = ti->private;
165 list_for_each_entry_safe(pgpath, tmp, pgpaths, list) {
166 list_del(&pgpath->list);
167 if (m->hw_handler_name)
168 scsi_dh_detach(bdev_get_queue(pgpath->path.dev->bdev));
169 dm_put_device(ti, pgpath->path.dev);
174 static void free_priority_group(struct priority_group *pg,
175 struct dm_target *ti)
177 struct path_selector *ps = &pg->ps;
180 ps->type->destroy(ps);
181 dm_put_path_selector(ps->type);
184 free_pgpaths(&pg->pgpaths, ti);
188 static struct multipath *alloc_multipath(struct dm_target *ti)
192 m = kzalloc(sizeof(*m), GFP_KERNEL);
194 INIT_LIST_HEAD(&m->priority_groups);
195 INIT_LIST_HEAD(&m->queued_ios);
196 spin_lock_init(&m->lock);
198 m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT;
199 INIT_WORK(&m->process_queued_ios, process_queued_ios);
200 INIT_WORK(&m->trigger_event, trigger_event);
201 init_waitqueue_head(&m->pg_init_wait);
202 mutex_init(&m->work_mutex);
203 m->mpio_pool = mempool_create_slab_pool(MIN_IOS, _mpio_cache);
215 static void free_multipath(struct multipath *m)
217 struct priority_group *pg, *tmp;
219 list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) {
221 free_priority_group(pg, m->ti);
224 kfree(m->hw_handler_name);
225 kfree(m->hw_handler_params);
226 mempool_destroy(m->mpio_pool);
231 /*-----------------------------------------------
233 *-----------------------------------------------*/
235 static void __pg_init_all_paths(struct multipath *m)
237 struct pgpath *pgpath;
238 unsigned long pg_init_delay = 0;
241 m->pg_init_required = 0;
242 if (m->pg_init_delay_retry)
243 pg_init_delay = msecs_to_jiffies(m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT ?
244 m->pg_init_delay_msecs : DM_PG_INIT_DELAY_MSECS);
245 list_for_each_entry(pgpath, &m->current_pg->pgpaths, list) {
246 /* Skip failed paths */
247 if (!pgpath->is_active)
249 if (queue_delayed_work(kmpath_handlerd, &pgpath->activate_path,
251 m->pg_init_in_progress++;
255 static void __switch_pg(struct multipath *m, struct pgpath *pgpath)
257 m->current_pg = pgpath->pg;
259 /* Must we initialise the PG first, and queue I/O till it's ready? */
260 if (m->hw_handler_name) {
261 m->pg_init_required = 1;
264 m->pg_init_required = 0;
268 m->pg_init_count = 0;
271 static int __choose_path_in_pg(struct multipath *m, struct priority_group *pg,
274 struct dm_path *path;
276 path = pg->ps.type->select_path(&pg->ps, &m->repeat_count, nr_bytes);
280 m->current_pgpath = path_to_pgpath(path);
282 if (m->current_pg != pg)
283 __switch_pg(m, m->current_pgpath);
288 static void __choose_pgpath(struct multipath *m, size_t nr_bytes)
290 struct priority_group *pg;
291 unsigned bypassed = 1;
293 if (!m->nr_valid_paths)
296 /* Were we instructed to switch PG? */
300 if (!__choose_path_in_pg(m, pg, nr_bytes))
304 /* Don't change PG until it has no remaining paths */
305 if (m->current_pg && !__choose_path_in_pg(m, m->current_pg, nr_bytes))
309 * Loop through priority groups until we find a valid path.
310 * First time we skip PGs marked 'bypassed'.
311 * Second time we only try the ones we skipped.
314 list_for_each_entry(pg, &m->priority_groups, list) {
315 if (pg->bypassed == bypassed)
317 if (!__choose_path_in_pg(m, pg, nr_bytes))
320 } while (bypassed--);
323 m->current_pgpath = NULL;
324 m->current_pg = NULL;
328 * Check whether bios must be queued in the device-mapper core rather
329 * than here in the target.
331 * m->lock must be held on entry.
333 * If m->queue_if_no_path and m->saved_queue_if_no_path hold the
334 * same value then we are not between multipath_presuspend()
335 * and multipath_resume() calls and we have no need to check
336 * for the DMF_NOFLUSH_SUSPENDING flag.
338 static int __must_push_back(struct multipath *m)
340 return (m->queue_if_no_path != m->saved_queue_if_no_path &&
341 dm_noflush_suspending(m->ti));
344 static int map_io(struct multipath *m, struct request *clone,
345 struct dm_mpath_io *mpio, unsigned was_queued)
347 int r = DM_MAPIO_REMAPPED;
348 size_t nr_bytes = blk_rq_bytes(clone);
350 struct pgpath *pgpath;
351 struct block_device *bdev;
353 spin_lock_irqsave(&m->lock, flags);
355 /* Do we need to select a new pgpath? */
356 if (!m->current_pgpath ||
357 (!m->queue_io && (m->repeat_count && --m->repeat_count == 0)))
358 __choose_pgpath(m, nr_bytes);
360 pgpath = m->current_pgpath;
365 if ((pgpath && m->queue_io) ||
366 (!pgpath && m->queue_if_no_path)) {
367 /* Queue for the daemon to resubmit */
368 list_add_tail(&clone->queuelist, &m->queued_ios);
370 if ((m->pg_init_required && !m->pg_init_in_progress) ||
372 queue_work(kmultipathd, &m->process_queued_ios);
374 r = DM_MAPIO_SUBMITTED;
376 bdev = pgpath->path.dev->bdev;
377 clone->q = bdev_get_queue(bdev);
378 clone->rq_disk = bdev->bd_disk;
379 } else if (__must_push_back(m))
380 r = DM_MAPIO_REQUEUE;
382 r = -EIO; /* Failed */
384 mpio->pgpath = pgpath;
385 mpio->nr_bytes = nr_bytes;
387 if (r == DM_MAPIO_REMAPPED && pgpath->pg->ps.type->start_io)
388 pgpath->pg->ps.type->start_io(&pgpath->pg->ps, &pgpath->path,
391 spin_unlock_irqrestore(&m->lock, flags);
397 * If we run out of usable paths, should we queue I/O or error it?
399 static int queue_if_no_path(struct multipath *m, unsigned queue_if_no_path,
400 unsigned save_old_value)
404 spin_lock_irqsave(&m->lock, flags);
407 m->saved_queue_if_no_path = m->queue_if_no_path;
409 m->saved_queue_if_no_path = queue_if_no_path;
410 m->queue_if_no_path = queue_if_no_path;
411 if (!m->queue_if_no_path && m->queue_size)
412 queue_work(kmultipathd, &m->process_queued_ios);
414 spin_unlock_irqrestore(&m->lock, flags);
419 /*-----------------------------------------------------------------
420 * The multipath daemon is responsible for resubmitting queued ios.
421 *---------------------------------------------------------------*/
423 static void dispatch_queued_ios(struct multipath *m)
427 struct dm_mpath_io *mpio;
428 union map_info *info;
429 struct request *clone, *n;
432 spin_lock_irqsave(&m->lock, flags);
433 list_splice_init(&m->queued_ios, &cl);
434 spin_unlock_irqrestore(&m->lock, flags);
436 list_for_each_entry_safe(clone, n, &cl, queuelist) {
437 list_del_init(&clone->queuelist);
439 info = dm_get_rq_mapinfo(clone);
442 r = map_io(m, clone, mpio, 1);
444 mempool_free(mpio, m->mpio_pool);
445 dm_kill_unmapped_request(clone, r);
446 } else if (r == DM_MAPIO_REMAPPED)
447 dm_dispatch_request(clone);
448 else if (r == DM_MAPIO_REQUEUE) {
449 mempool_free(mpio, m->mpio_pool);
450 dm_requeue_unmapped_request(clone);
455 static void process_queued_ios(struct work_struct *work)
457 struct multipath *m =
458 container_of(work, struct multipath, process_queued_ios);
459 struct pgpath *pgpath = NULL;
460 unsigned must_queue = 1;
463 spin_lock_irqsave(&m->lock, flags);
468 if (!m->current_pgpath)
469 __choose_pgpath(m, 0);
471 pgpath = m->current_pgpath;
473 if ((pgpath && !m->queue_io) ||
474 (!pgpath && !m->queue_if_no_path))
477 if (m->pg_init_required && !m->pg_init_in_progress && pgpath)
478 __pg_init_all_paths(m);
481 spin_unlock_irqrestore(&m->lock, flags);
483 dispatch_queued_ios(m);
487 * An event is triggered whenever a path is taken out of use.
488 * Includes path failure and PG bypass.
490 static void trigger_event(struct work_struct *work)
492 struct multipath *m =
493 container_of(work, struct multipath, trigger_event);
495 dm_table_event(m->ti->table);
498 /*-----------------------------------------------------------------
499 * Constructor/argument parsing:
500 * <#multipath feature args> [<arg>]*
501 * <#hw_handler args> [hw_handler [<arg>]*]
503 * <initial priority group>
504 * [<selector> <#selector args> [<arg>]*
505 * <#paths> <#per-path selector args>
506 * [<path> [<arg>]* ]+ ]+
507 *---------------------------------------------------------------*/
514 static int read_param(struct param *param, char *str, unsigned *v, char **error)
517 (sscanf(str, "%u", v) != 1) ||
520 *error = param->error;
532 static char *shift(struct arg_set *as)
546 static void consume(struct arg_set *as, unsigned n)
548 BUG_ON (as->argc < n);
553 static int parse_path_selector(struct arg_set *as, struct priority_group *pg,
554 struct dm_target *ti)
557 struct path_selector_type *pst;
560 static struct param _params[] = {
561 {0, 1024, "invalid number of path selector args"},
564 pst = dm_get_path_selector(shift(as));
566 ti->error = "unknown path selector type";
570 r = read_param(_params, shift(as), &ps_argc, &ti->error);
572 dm_put_path_selector(pst);
576 if (ps_argc > as->argc) {
577 dm_put_path_selector(pst);
578 ti->error = "not enough arguments for path selector";
582 r = pst->create(&pg->ps, ps_argc, as->argv);
584 dm_put_path_selector(pst);
585 ti->error = "path selector constructor failed";
590 consume(as, ps_argc);
595 static struct pgpath *parse_path(struct arg_set *as, struct path_selector *ps,
596 struct dm_target *ti)
600 struct multipath *m = ti->private;
602 /* we need at least a path arg */
604 ti->error = "no device given";
605 return ERR_PTR(-EINVAL);
610 return ERR_PTR(-ENOMEM);
612 r = dm_get_device(ti, shift(as), dm_table_get_mode(ti->table),
615 ti->error = "error getting device";
619 if (m->hw_handler_name) {
620 struct request_queue *q = bdev_get_queue(p->path.dev->bdev);
622 r = scsi_dh_attach(q, m->hw_handler_name);
625 * Already attached to different hw_handler,
626 * try to reattach with correct one.
629 r = scsi_dh_attach(q, m->hw_handler_name);
633 ti->error = "error attaching hardware handler";
634 dm_put_device(ti, p->path.dev);
638 if (m->hw_handler_params) {
639 r = scsi_dh_set_params(q, m->hw_handler_params);
641 ti->error = "unable to set hardware "
642 "handler parameters";
644 dm_put_device(ti, p->path.dev);
650 r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
652 dm_put_device(ti, p->path.dev);
663 static struct priority_group *parse_priority_group(struct arg_set *as,
666 static struct param _params[] = {
667 {1, 1024, "invalid number of paths"},
668 {0, 1024, "invalid number of selector args"}
672 unsigned i, nr_selector_args, nr_params;
673 struct priority_group *pg;
674 struct dm_target *ti = m->ti;
678 ti->error = "not enough priority group arguments";
679 return ERR_PTR(-EINVAL);
682 pg = alloc_priority_group();
684 ti->error = "couldn't allocate priority group";
685 return ERR_PTR(-ENOMEM);
689 r = parse_path_selector(as, pg, ti);
696 r = read_param(_params, shift(as), &pg->nr_pgpaths, &ti->error);
700 r = read_param(_params + 1, shift(as), &nr_selector_args, &ti->error);
704 nr_params = 1 + nr_selector_args;
705 for (i = 0; i < pg->nr_pgpaths; i++) {
706 struct pgpath *pgpath;
707 struct arg_set path_args;
709 if (as->argc < nr_params) {
710 ti->error = "not enough path parameters";
715 path_args.argc = nr_params;
716 path_args.argv = as->argv;
718 pgpath = parse_path(&path_args, &pg->ps, ti);
719 if (IS_ERR(pgpath)) {
725 list_add_tail(&pgpath->list, &pg->pgpaths);
726 consume(as, nr_params);
732 free_priority_group(pg, ti);
736 static int parse_hw_handler(struct arg_set *as, struct multipath *m)
740 struct dm_target *ti = m->ti;
742 static struct param _params[] = {
743 {0, 1024, "invalid number of hardware handler args"},
746 if (read_param(_params, shift(as), &hw_argc, &ti->error))
752 if (hw_argc > as->argc) {
753 ti->error = "not enough arguments for hardware handler";
757 m->hw_handler_name = kstrdup(shift(as), GFP_KERNEL);
758 request_module("scsi_dh_%s", m->hw_handler_name);
759 if (scsi_dh_handler_exist(m->hw_handler_name) == 0) {
760 ti->error = "unknown hardware handler type";
769 for (i = 0; i <= hw_argc - 2; i++)
770 len += strlen(as->argv[i]) + 1;
771 p = m->hw_handler_params = kzalloc(len, GFP_KERNEL);
773 ti->error = "memory allocation failed";
777 j = sprintf(p, "%d", hw_argc - 1);
778 for (i = 0, p+=j+1; i <= hw_argc - 2; i++, p+=j+1)
779 j = sprintf(p, "%s", as->argv[i]);
781 consume(as, hw_argc - 1);
785 kfree(m->hw_handler_name);
786 m->hw_handler_name = NULL;
790 static int parse_features(struct arg_set *as, struct multipath *m)
794 struct dm_target *ti = m->ti;
795 const char *param_name;
797 static struct param _params[] = {
798 {0, 5, "invalid number of feature args"},
799 {1, 50, "pg_init_retries must be between 1 and 50"},
800 {0, 60000, "pg_init_delay_msecs must be between 0 and 60000"},
803 r = read_param(_params, shift(as), &argc, &ti->error);
810 if (argc > as->argc) {
811 ti->error = "not enough arguments for features";
816 param_name = shift(as);
819 if (!strnicmp(param_name, MESG_STR("queue_if_no_path"))) {
820 r = queue_if_no_path(m, 1, 0);
824 if (!strnicmp(param_name, MESG_STR("pg_init_retries")) &&
826 r = read_param(_params + 1, shift(as),
827 &m->pg_init_retries, &ti->error);
832 if (!strnicmp(param_name, MESG_STR("pg_init_delay_msecs")) &&
834 r = read_param(_params + 2, shift(as),
835 &m->pg_init_delay_msecs, &ti->error);
840 ti->error = "Unrecognised multipath feature request";
842 } while (argc && !r);
847 static int multipath_ctr(struct dm_target *ti, unsigned int argc,
850 /* target parameters */
851 static struct param _params[] = {
852 {0, 1024, "invalid number of priority groups"},
853 {0, 1024, "invalid initial priority group number"},
859 unsigned pg_count = 0;
860 unsigned next_pg_num;
865 m = alloc_multipath(ti);
867 ti->error = "can't allocate multipath";
871 r = parse_features(&as, m);
875 r = parse_hw_handler(&as, m);
879 r = read_param(_params, shift(&as), &m->nr_priority_groups, &ti->error);
883 r = read_param(_params + 1, shift(&as), &next_pg_num, &ti->error);
887 if ((!m->nr_priority_groups && next_pg_num) ||
888 (m->nr_priority_groups && !next_pg_num)) {
889 ti->error = "invalid initial priority group";
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;
919 ti->num_discard_requests = 1;
928 static void multipath_wait_for_pg_init_completion(struct multipath *m)
930 DECLARE_WAITQUEUE(wait, current);
933 add_wait_queue(&m->pg_init_wait, &wait);
936 set_current_state(TASK_UNINTERRUPTIBLE);
938 spin_lock_irqsave(&m->lock, flags);
939 if (!m->pg_init_in_progress) {
940 spin_unlock_irqrestore(&m->lock, flags);
943 spin_unlock_irqrestore(&m->lock, flags);
947 set_current_state(TASK_RUNNING);
949 remove_wait_queue(&m->pg_init_wait, &wait);
952 static void flush_multipath_work(struct multipath *m)
954 flush_workqueue(kmpath_handlerd);
955 multipath_wait_for_pg_init_completion(m);
956 flush_workqueue(kmultipathd);
957 flush_work_sync(&m->trigger_event);
960 static void multipath_dtr(struct dm_target *ti)
962 struct multipath *m = ti->private;
964 flush_multipath_work(m);
969 * Map cloned requests
971 static int multipath_map(struct dm_target *ti, struct request *clone,
972 union map_info *map_context)
975 struct dm_mpath_io *mpio;
976 struct multipath *m = (struct multipath *) ti->private;
978 mpio = mempool_alloc(m->mpio_pool, GFP_ATOMIC);
980 /* ENOMEM, requeue */
981 return DM_MAPIO_REQUEUE;
982 memset(mpio, 0, sizeof(*mpio));
984 map_context->ptr = mpio;
985 clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
986 r = map_io(m, clone, mpio, 0);
987 if (r < 0 || r == DM_MAPIO_REQUEUE)
988 mempool_free(mpio, m->mpio_pool);
994 * Take a path out of use.
996 static int fail_path(struct pgpath *pgpath)
999 struct multipath *m = pgpath->pg->m;
1001 spin_lock_irqsave(&m->lock, flags);
1003 if (!pgpath->is_active)
1006 DMWARN("Failing path %s.", pgpath->path.dev->name);
1008 pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
1009 pgpath->is_active = 0;
1010 pgpath->fail_count++;
1012 m->nr_valid_paths--;
1014 if (pgpath == m->current_pgpath)
1015 m->current_pgpath = NULL;
1017 dm_path_uevent(DM_UEVENT_PATH_FAILED, m->ti,
1018 pgpath->path.dev->name, m->nr_valid_paths);
1020 schedule_work(&m->trigger_event);
1023 spin_unlock_irqrestore(&m->lock, flags);
1029 * Reinstate a previously-failed path
1031 static int reinstate_path(struct pgpath *pgpath)
1034 unsigned long flags;
1035 struct multipath *m = pgpath->pg->m;
1037 spin_lock_irqsave(&m->lock, flags);
1039 if (pgpath->is_active)
1042 if (!pgpath->pg->ps.type->reinstate_path) {
1043 DMWARN("Reinstate path not supported by path selector %s",
1044 pgpath->pg->ps.type->name);
1049 r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
1053 pgpath->is_active = 1;
1055 if (!m->nr_valid_paths++ && m->queue_size) {
1056 m->current_pgpath = NULL;
1057 queue_work(kmultipathd, &m->process_queued_ios);
1058 } else if (m->hw_handler_name && (m->current_pg == pgpath->pg)) {
1059 if (queue_work(kmpath_handlerd, &pgpath->activate_path.work))
1060 m->pg_init_in_progress++;
1063 dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti,
1064 pgpath->path.dev->name, m->nr_valid_paths);
1066 schedule_work(&m->trigger_event);
1069 spin_unlock_irqrestore(&m->lock, flags);
1075 * Fail or reinstate all paths that match the provided struct dm_dev.
1077 static int action_dev(struct multipath *m, struct dm_dev *dev,
1081 struct pgpath *pgpath;
1082 struct priority_group *pg;
1084 list_for_each_entry(pg, &m->priority_groups, list) {
1085 list_for_each_entry(pgpath, &pg->pgpaths, list) {
1086 if (pgpath->path.dev == dev)
1095 * Temporarily try to avoid having to use the specified PG
1097 static void bypass_pg(struct multipath *m, struct priority_group *pg,
1100 unsigned long flags;
1102 spin_lock_irqsave(&m->lock, flags);
1104 pg->bypassed = bypassed;
1105 m->current_pgpath = NULL;
1106 m->current_pg = NULL;
1108 spin_unlock_irqrestore(&m->lock, flags);
1110 schedule_work(&m->trigger_event);
1114 * Switch to using the specified PG from the next I/O that gets mapped
1116 static int switch_pg_num(struct multipath *m, const char *pgstr)
1118 struct priority_group *pg;
1120 unsigned long flags;
1122 if (!pgstr || (sscanf(pgstr, "%u", &pgnum) != 1) || !pgnum ||
1123 (pgnum > m->nr_priority_groups)) {
1124 DMWARN("invalid PG number supplied to switch_pg_num");
1128 spin_lock_irqsave(&m->lock, flags);
1129 list_for_each_entry(pg, &m->priority_groups, list) {
1134 m->current_pgpath = NULL;
1135 m->current_pg = NULL;
1138 spin_unlock_irqrestore(&m->lock, flags);
1140 schedule_work(&m->trigger_event);
1145 * Set/clear bypassed status of a PG.
1146 * PGs are numbered upwards from 1 in the order they were declared.
1148 static int bypass_pg_num(struct multipath *m, const char *pgstr, int bypassed)
1150 struct priority_group *pg;
1153 if (!pgstr || (sscanf(pgstr, "%u", &pgnum) != 1) || !pgnum ||
1154 (pgnum > m->nr_priority_groups)) {
1155 DMWARN("invalid PG number supplied to bypass_pg");
1159 list_for_each_entry(pg, &m->priority_groups, list) {
1164 bypass_pg(m, pg, bypassed);
1169 * Should we retry pg_init immediately?
1171 static int pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath)
1173 unsigned long flags;
1174 int limit_reached = 0;
1176 spin_lock_irqsave(&m->lock, flags);
1178 if (m->pg_init_count <= m->pg_init_retries)
1179 m->pg_init_required = 1;
1183 spin_unlock_irqrestore(&m->lock, flags);
1185 return limit_reached;
1188 static void pg_init_done(void *data, int errors)
1190 struct pgpath *pgpath = data;
1191 struct priority_group *pg = pgpath->pg;
1192 struct multipath *m = pg->m;
1193 unsigned long flags;
1194 unsigned delay_retry = 0;
1196 /* device or driver problems */
1201 if (!m->hw_handler_name) {
1205 DMERR("Could not failover the device: Handler scsi_dh_%s "
1206 "Error %d.", m->hw_handler_name, errors);
1208 * Fail path for now, so we do not ping pong
1212 case SCSI_DH_DEV_TEMP_BUSY:
1214 * Probably doing something like FW upgrade on the
1215 * controller so try the other pg.
1217 bypass_pg(m, pg, 1);
1220 /* Wait before retrying. */
1222 case SCSI_DH_IMM_RETRY:
1223 case SCSI_DH_RES_TEMP_UNAVAIL:
1224 if (pg_init_limit_reached(m, pgpath))
1230 * We probably do not want to fail the path for a device
1231 * error, but this is what the old dm did. In future
1232 * patches we can do more advanced handling.
1237 spin_lock_irqsave(&m->lock, flags);
1239 if (pgpath == m->current_pgpath) {
1240 DMERR("Could not failover device. Error %d.", errors);
1241 m->current_pgpath = NULL;
1242 m->current_pg = NULL;
1244 } else if (!m->pg_init_required)
1247 if (--m->pg_init_in_progress)
1248 /* Activations of other paths are still on going */
1251 if (!m->pg_init_required)
1254 m->pg_init_delay_retry = delay_retry;
1255 queue_work(kmultipathd, &m->process_queued_ios);
1258 * Wake up any thread waiting to suspend.
1260 wake_up(&m->pg_init_wait);
1263 spin_unlock_irqrestore(&m->lock, flags);
1266 static void activate_path(struct work_struct *work)
1268 struct pgpath *pgpath =
1269 container_of(work, struct pgpath, activate_path.work);
1271 scsi_dh_activate(bdev_get_queue(pgpath->path.dev->bdev),
1272 pg_init_done, pgpath);
1278 static int do_end_io(struct multipath *m, struct request *clone,
1279 int error, struct dm_mpath_io *mpio)
1282 * We don't queue any clone request inside the multipath target
1283 * during end I/O handling, since those clone requests don't have
1284 * bio clones. If we queue them inside the multipath target,
1285 * we need to make bio clones, that requires memory allocation.
1286 * (See drivers/md/dm.c:end_clone_bio() about why the clone requests
1287 * don't have bio clones.)
1288 * Instead of queueing the clone request here, we queue the original
1289 * request into dm core, which will remake a clone request and
1290 * clone bios for it and resubmit it later.
1292 int r = DM_ENDIO_REQUEUE;
1293 unsigned long flags;
1295 if (!error && !clone->errors)
1296 return 0; /* I/O complete */
1298 if (error == -EOPNOTSUPP || error == -EREMOTEIO || error == -EILSEQ)
1302 fail_path(mpio->pgpath);
1304 spin_lock_irqsave(&m->lock, flags);
1305 if (!m->nr_valid_paths) {
1306 if (!m->queue_if_no_path) {
1307 if (!__must_push_back(m))
1310 if (error == -EBADE)
1314 spin_unlock_irqrestore(&m->lock, flags);
1319 static int multipath_end_io(struct dm_target *ti, struct request *clone,
1320 int error, union map_info *map_context)
1322 struct multipath *m = ti->private;
1323 struct dm_mpath_io *mpio = map_context->ptr;
1324 struct pgpath *pgpath = mpio->pgpath;
1325 struct path_selector *ps;
1328 r = do_end_io(m, clone, error, mpio);
1330 ps = &pgpath->pg->ps;
1331 if (ps->type->end_io)
1332 ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
1334 mempool_free(mpio, m->mpio_pool);
1340 * Suspend can't complete until all the I/O is processed so if
1341 * the last path fails we must error any remaining I/O.
1342 * Note that if the freeze_bdev fails while suspending, the
1343 * queue_if_no_path state is lost - userspace should reset it.
1345 static void multipath_presuspend(struct dm_target *ti)
1347 struct multipath *m = (struct multipath *) ti->private;
1349 queue_if_no_path(m, 0, 1);
1352 static void multipath_postsuspend(struct dm_target *ti)
1354 struct multipath *m = ti->private;
1356 mutex_lock(&m->work_mutex);
1357 flush_multipath_work(m);
1358 mutex_unlock(&m->work_mutex);
1362 * Restore the queue_if_no_path setting.
1364 static void multipath_resume(struct dm_target *ti)
1366 struct multipath *m = (struct multipath *) ti->private;
1367 unsigned long flags;
1369 spin_lock_irqsave(&m->lock, flags);
1370 m->queue_if_no_path = m->saved_queue_if_no_path;
1371 spin_unlock_irqrestore(&m->lock, flags);
1375 * Info output has the following format:
1376 * num_multipath_feature_args [multipath_feature_args]*
1377 * num_handler_status_args [handler_status_args]*
1378 * num_groups init_group_number
1379 * [A|D|E num_ps_status_args [ps_status_args]*
1380 * num_paths num_selector_args
1381 * [path_dev A|F fail_count [selector_args]* ]+ ]+
1383 * Table output has the following format (identical to the constructor string):
1384 * num_feature_args [features_args]*
1385 * num_handler_args hw_handler [hw_handler_args]*
1386 * num_groups init_group_number
1387 * [priority selector-name num_ps_args [ps_args]*
1388 * num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
1390 static int multipath_status(struct dm_target *ti, status_type_t type,
1391 char *result, unsigned int maxlen)
1394 unsigned long flags;
1395 struct multipath *m = (struct multipath *) ti->private;
1396 struct priority_group *pg;
1401 spin_lock_irqsave(&m->lock, flags);
1404 if (type == STATUSTYPE_INFO)
1405 DMEMIT("2 %u %u ", m->queue_size, m->pg_init_count);
1407 DMEMIT("%u ", m->queue_if_no_path +
1408 (m->pg_init_retries > 0) * 2 +
1409 (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT) * 2);
1410 if (m->queue_if_no_path)
1411 DMEMIT("queue_if_no_path ");
1412 if (m->pg_init_retries)
1413 DMEMIT("pg_init_retries %u ", m->pg_init_retries);
1414 if (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT)
1415 DMEMIT("pg_init_delay_msecs %u ", m->pg_init_delay_msecs);
1418 if (!m->hw_handler_name || type == STATUSTYPE_INFO)
1421 DMEMIT("1 %s ", m->hw_handler_name);
1423 DMEMIT("%u ", m->nr_priority_groups);
1426 pg_num = m->next_pg->pg_num;
1427 else if (m->current_pg)
1428 pg_num = m->current_pg->pg_num;
1430 pg_num = (m->nr_priority_groups ? 1 : 0);
1432 DMEMIT("%u ", pg_num);
1435 case STATUSTYPE_INFO:
1436 list_for_each_entry(pg, &m->priority_groups, list) {
1438 state = 'D'; /* Disabled */
1439 else if (pg == m->current_pg)
1440 state = 'A'; /* Currently Active */
1442 state = 'E'; /* Enabled */
1444 DMEMIT("%c ", state);
1446 if (pg->ps.type->status)
1447 sz += pg->ps.type->status(&pg->ps, NULL, type,
1453 DMEMIT("%u %u ", pg->nr_pgpaths,
1454 pg->ps.type->info_args);
1456 list_for_each_entry(p, &pg->pgpaths, list) {
1457 DMEMIT("%s %s %u ", p->path.dev->name,
1458 p->is_active ? "A" : "F",
1460 if (pg->ps.type->status)
1461 sz += pg->ps.type->status(&pg->ps,
1462 &p->path, type, result + sz,
1468 case STATUSTYPE_TABLE:
1469 list_for_each_entry(pg, &m->priority_groups, list) {
1470 DMEMIT("%s ", pg->ps.type->name);
1472 if (pg->ps.type->status)
1473 sz += pg->ps.type->status(&pg->ps, NULL, type,
1479 DMEMIT("%u %u ", pg->nr_pgpaths,
1480 pg->ps.type->table_args);
1482 list_for_each_entry(p, &pg->pgpaths, list) {
1483 DMEMIT("%s ", p->path.dev->name);
1484 if (pg->ps.type->status)
1485 sz += pg->ps.type->status(&pg->ps,
1486 &p->path, type, result + sz,
1493 spin_unlock_irqrestore(&m->lock, flags);
1498 static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
1502 struct multipath *m = (struct multipath *) ti->private;
1505 mutex_lock(&m->work_mutex);
1507 if (dm_suspended(ti)) {
1513 if (!strnicmp(argv[0], MESG_STR("queue_if_no_path"))) {
1514 r = queue_if_no_path(m, 1, 0);
1516 } else if (!strnicmp(argv[0], MESG_STR("fail_if_no_path"))) {
1517 r = queue_if_no_path(m, 0, 0);
1523 DMWARN("Unrecognised multipath message received.");
1527 if (!strnicmp(argv[0], MESG_STR("disable_group"))) {
1528 r = bypass_pg_num(m, argv[1], 1);
1530 } else if (!strnicmp(argv[0], MESG_STR("enable_group"))) {
1531 r = bypass_pg_num(m, argv[1], 0);
1533 } else if (!strnicmp(argv[0], MESG_STR("switch_group"))) {
1534 r = switch_pg_num(m, argv[1]);
1536 } else if (!strnicmp(argv[0], MESG_STR("reinstate_path")))
1537 action = reinstate_path;
1538 else if (!strnicmp(argv[0], MESG_STR("fail_path")))
1541 DMWARN("Unrecognised multipath message received.");
1545 r = dm_get_device(ti, argv[1], dm_table_get_mode(ti->table), &dev);
1547 DMWARN("message: error getting device %s",
1552 r = action_dev(m, dev, action);
1554 dm_put_device(ti, dev);
1557 mutex_unlock(&m->work_mutex);
1561 static int multipath_ioctl(struct dm_target *ti, unsigned int cmd,
1564 struct multipath *m = (struct multipath *) ti->private;
1565 struct block_device *bdev = NULL;
1567 unsigned long flags;
1570 spin_lock_irqsave(&m->lock, flags);
1572 if (!m->current_pgpath)
1573 __choose_pgpath(m, 0);
1575 if (m->current_pgpath) {
1576 bdev = m->current_pgpath->path.dev->bdev;
1577 mode = m->current_pgpath->path.dev->mode;
1585 spin_unlock_irqrestore(&m->lock, flags);
1587 return r ? : __blkdev_driver_ioctl(bdev, mode, cmd, arg);
1590 static int multipath_iterate_devices(struct dm_target *ti,
1591 iterate_devices_callout_fn fn, void *data)
1593 struct multipath *m = ti->private;
1594 struct priority_group *pg;
1598 list_for_each_entry(pg, &m->priority_groups, list) {
1599 list_for_each_entry(p, &pg->pgpaths, list) {
1600 ret = fn(ti, p->path.dev, ti->begin, ti->len, data);
1610 static int __pgpath_busy(struct pgpath *pgpath)
1612 struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
1614 return dm_underlying_device_busy(q);
1618 * We return "busy", only when we can map I/Os but underlying devices
1619 * are busy (so even if we map I/Os now, the I/Os will wait on
1620 * the underlying queue).
1621 * In other words, if we want to kill I/Os or queue them inside us
1622 * due to map unavailability, we don't return "busy". Otherwise,
1623 * dm core won't give us the I/Os and we can't do what we want.
1625 static int multipath_busy(struct dm_target *ti)
1627 int busy = 0, has_active = 0;
1628 struct multipath *m = ti->private;
1629 struct priority_group *pg;
1630 struct pgpath *pgpath;
1631 unsigned long flags;
1633 spin_lock_irqsave(&m->lock, flags);
1635 /* Guess which priority_group will be used at next mapping time */
1636 if (unlikely(!m->current_pgpath && m->next_pg))
1638 else if (likely(m->current_pg))
1642 * We don't know which pg will be used at next mapping time.
1643 * We don't call __choose_pgpath() here to avoid to trigger
1644 * pg_init just by busy checking.
1645 * So we don't know whether underlying devices we will be using
1646 * at next mapping time are busy or not. Just try mapping.
1651 * If there is one non-busy active path at least, the path selector
1652 * will be able to select it. So we consider such a pg as not busy.
1655 list_for_each_entry(pgpath, &pg->pgpaths, list)
1656 if (pgpath->is_active) {
1659 if (!__pgpath_busy(pgpath)) {
1667 * No active path in this pg, so this pg won't be used and
1668 * the current_pg will be changed at next mapping time.
1669 * We need to try mapping to determine it.
1674 spin_unlock_irqrestore(&m->lock, flags);
1679 /*-----------------------------------------------------------------
1681 *---------------------------------------------------------------*/
1682 static struct target_type multipath_target = {
1683 .name = "multipath",
1684 .version = {1, 3, 0},
1685 .module = THIS_MODULE,
1686 .ctr = multipath_ctr,
1687 .dtr = multipath_dtr,
1688 .map_rq = multipath_map,
1689 .rq_end_io = multipath_end_io,
1690 .presuspend = multipath_presuspend,
1691 .postsuspend = multipath_postsuspend,
1692 .resume = multipath_resume,
1693 .status = multipath_status,
1694 .message = multipath_message,
1695 .ioctl = multipath_ioctl,
1696 .iterate_devices = multipath_iterate_devices,
1697 .busy = multipath_busy,
1700 static int __init dm_multipath_init(void)
1704 /* allocate a slab for the dm_ios */
1705 _mpio_cache = KMEM_CACHE(dm_mpath_io, 0);
1709 r = dm_register_target(&multipath_target);
1711 DMERR("register failed %d", r);
1712 kmem_cache_destroy(_mpio_cache);
1716 kmultipathd = alloc_workqueue("kmpathd", WQ_MEM_RECLAIM, 0);
1718 DMERR("failed to create workqueue kmpathd");
1719 dm_unregister_target(&multipath_target);
1720 kmem_cache_destroy(_mpio_cache);
1725 * A separate workqueue is used to handle the device handlers
1726 * to avoid overloading existing workqueue. Overloading the
1727 * old workqueue would also create a bottleneck in the
1728 * path of the storage hardware device activation.
1730 kmpath_handlerd = alloc_ordered_workqueue("kmpath_handlerd",
1732 if (!kmpath_handlerd) {
1733 DMERR("failed to create workqueue kmpath_handlerd");
1734 destroy_workqueue(kmultipathd);
1735 dm_unregister_target(&multipath_target);
1736 kmem_cache_destroy(_mpio_cache);
1740 DMINFO("version %u.%u.%u loaded",
1741 multipath_target.version[0], multipath_target.version[1],
1742 multipath_target.version[2]);
1747 static void __exit dm_multipath_exit(void)
1749 destroy_workqueue(kmpath_handlerd);
1750 destroy_workqueue(kmultipathd);
1752 dm_unregister_target(&multipath_target);
1753 kmem_cache_destroy(_mpio_cache);
1756 module_init(dm_multipath_init);
1757 module_exit(dm_multipath_exit);
1759 MODULE_DESCRIPTION(DM_NAME " multipath target");
1760 MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
1761 MODULE_LICENSE("GPL");