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 deactivate_path
;
37 struct work_struct activate_path
;
40 #define path_to_pgpath(__pgp) container_of((__pgp), struct pgpath, path)
43 * Paths are grouped into Priority Groups and numbered from 1 upwards.
44 * Each has a path selector which controls which path gets used.
46 struct priority_group
{
47 struct list_head list
;
49 struct multipath
*m
; /* Owning multipath instance */
50 struct path_selector ps
;
52 unsigned pg_num
; /* Reference number */
53 unsigned bypassed
; /* Temporarily bypass this PG? */
55 unsigned nr_pgpaths
; /* Number of paths in PG */
56 struct list_head pgpaths
;
59 /* Multipath context */
61 struct list_head list
;
66 const char *hw_handler_name
;
67 char *hw_handler_params
;
68 unsigned nr_priority_groups
;
69 struct list_head priority_groups
;
70 unsigned pg_init_required
; /* pg_init needs calling? */
71 unsigned pg_init_in_progress
; /* Only one pg_init allowed at once */
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
);
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 blk_abort_queue(pgpath
->path
.dev
->bdev
->bd_disk
->queue
);
151 static struct priority_group
*alloc_priority_group(void)
153 struct priority_group
*pg
;
155 pg
= kzalloc(sizeof(*pg
), GFP_KERNEL
);
158 INIT_LIST_HEAD(&pg
->pgpaths
);
163 static void free_pgpaths(struct list_head
*pgpaths
, struct dm_target
*ti
)
165 struct pgpath
*pgpath
, *tmp
;
166 struct multipath
*m
= ti
->private;
168 list_for_each_entry_safe(pgpath
, tmp
, pgpaths
, list
) {
169 list_del(&pgpath
->list
);
170 if (m
->hw_handler_name
)
171 scsi_dh_detach(bdev_get_queue(pgpath
->path
.dev
->bdev
));
172 dm_put_device(ti
, pgpath
->path
.dev
);
177 static void free_priority_group(struct priority_group
*pg
,
178 struct dm_target
*ti
)
180 struct path_selector
*ps
= &pg
->ps
;
183 ps
->type
->destroy(ps
);
184 dm_put_path_selector(ps
->type
);
187 free_pgpaths(&pg
->pgpaths
, ti
);
191 static struct multipath
*alloc_multipath(struct dm_target
*ti
)
195 m
= kzalloc(sizeof(*m
), GFP_KERNEL
);
197 INIT_LIST_HEAD(&m
->priority_groups
);
198 INIT_LIST_HEAD(&m
->queued_ios
);
199 spin_lock_init(&m
->lock
);
201 INIT_WORK(&m
->process_queued_ios
, process_queued_ios
);
202 INIT_WORK(&m
->trigger_event
, trigger_event
);
203 mutex_init(&m
->work_mutex
);
204 m
->mpio_pool
= mempool_create_slab_pool(MIN_IOS
, _mpio_cache
);
216 static void free_multipath(struct multipath
*m
)
218 struct priority_group
*pg
, *tmp
;
220 list_for_each_entry_safe(pg
, tmp
, &m
->priority_groups
, list
) {
222 free_priority_group(pg
, m
->ti
);
225 kfree(m
->hw_handler_name
);
226 kfree(m
->hw_handler_params
);
227 mempool_destroy(m
->mpio_pool
);
232 /*-----------------------------------------------
234 *-----------------------------------------------*/
236 static void __switch_pg(struct multipath
*m
, struct pgpath
*pgpath
)
238 m
->current_pg
= pgpath
->pg
;
240 /* Must we initialise the PG first, and queue I/O till it's ready? */
241 if (m
->hw_handler_name
) {
242 m
->pg_init_required
= 1;
245 m
->pg_init_required
= 0;
249 m
->pg_init_count
= 0;
252 static int __choose_path_in_pg(struct multipath
*m
, struct priority_group
*pg
,
255 struct dm_path
*path
;
257 path
= pg
->ps
.type
->select_path(&pg
->ps
, &m
->repeat_count
, nr_bytes
);
261 m
->current_pgpath
= path_to_pgpath(path
);
263 if (m
->current_pg
!= pg
)
264 __switch_pg(m
, m
->current_pgpath
);
269 static void __choose_pgpath(struct multipath
*m
, size_t nr_bytes
)
271 struct priority_group
*pg
;
272 unsigned bypassed
= 1;
274 if (!m
->nr_valid_paths
)
277 /* Were we instructed to switch PG? */
281 if (!__choose_path_in_pg(m
, pg
, nr_bytes
))
285 /* Don't change PG until it has no remaining paths */
286 if (m
->current_pg
&& !__choose_path_in_pg(m
, m
->current_pg
, nr_bytes
))
290 * Loop through priority groups until we find a valid path.
291 * First time we skip PGs marked 'bypassed'.
292 * Second time we only try the ones we skipped.
295 list_for_each_entry(pg
, &m
->priority_groups
, list
) {
296 if (pg
->bypassed
== bypassed
)
298 if (!__choose_path_in_pg(m
, pg
, nr_bytes
))
301 } while (bypassed
--);
304 m
->current_pgpath
= NULL
;
305 m
->current_pg
= NULL
;
309 * Check whether bios must be queued in the device-mapper core rather
310 * than here in the target.
312 * m->lock must be held on entry.
314 * If m->queue_if_no_path and m->saved_queue_if_no_path hold the
315 * same value then we are not between multipath_presuspend()
316 * and multipath_resume() calls and we have no need to check
317 * for the DMF_NOFLUSH_SUSPENDING flag.
319 static int __must_push_back(struct multipath
*m
)
321 return (m
->queue_if_no_path
!= m
->saved_queue_if_no_path
&&
322 dm_noflush_suspending(m
->ti
));
325 static int map_io(struct multipath
*m
, struct request
*clone
,
326 struct dm_mpath_io
*mpio
, unsigned was_queued
)
328 int r
= DM_MAPIO_REMAPPED
;
329 size_t nr_bytes
= blk_rq_bytes(clone
);
331 struct pgpath
*pgpath
;
332 struct block_device
*bdev
;
334 spin_lock_irqsave(&m
->lock
, flags
);
336 /* Do we need to select a new pgpath? */
337 if (!m
->current_pgpath
||
338 (!m
->queue_io
&& (m
->repeat_count
&& --m
->repeat_count
== 0)))
339 __choose_pgpath(m
, nr_bytes
);
341 pgpath
= m
->current_pgpath
;
346 if ((pgpath
&& m
->queue_io
) ||
347 (!pgpath
&& m
->queue_if_no_path
)) {
348 /* Queue for the daemon to resubmit */
349 list_add_tail(&clone
->queuelist
, &m
->queued_ios
);
351 if ((m
->pg_init_required
&& !m
->pg_init_in_progress
) ||
353 queue_work(kmultipathd
, &m
->process_queued_ios
);
355 r
= DM_MAPIO_SUBMITTED
;
357 bdev
= pgpath
->path
.dev
->bdev
;
358 clone
->q
= bdev_get_queue(bdev
);
359 clone
->rq_disk
= bdev
->bd_disk
;
360 } else if (__must_push_back(m
))
361 r
= DM_MAPIO_REQUEUE
;
363 r
= -EIO
; /* Failed */
365 mpio
->pgpath
= pgpath
;
366 mpio
->nr_bytes
= nr_bytes
;
368 if (r
== DM_MAPIO_REMAPPED
&& pgpath
->pg
->ps
.type
->start_io
)
369 pgpath
->pg
->ps
.type
->start_io(&pgpath
->pg
->ps
, &pgpath
->path
,
372 spin_unlock_irqrestore(&m
->lock
, flags
);
378 * If we run out of usable paths, should we queue I/O or error it?
380 static int queue_if_no_path(struct multipath
*m
, unsigned queue_if_no_path
,
381 unsigned save_old_value
)
385 spin_lock_irqsave(&m
->lock
, flags
);
388 m
->saved_queue_if_no_path
= m
->queue_if_no_path
;
390 m
->saved_queue_if_no_path
= queue_if_no_path
;
391 m
->queue_if_no_path
= queue_if_no_path
;
392 if (!m
->queue_if_no_path
&& m
->queue_size
)
393 queue_work(kmultipathd
, &m
->process_queued_ios
);
395 spin_unlock_irqrestore(&m
->lock
, flags
);
400 /*-----------------------------------------------------------------
401 * The multipath daemon is responsible for resubmitting queued ios.
402 *---------------------------------------------------------------*/
404 static void dispatch_queued_ios(struct multipath
*m
)
408 struct dm_mpath_io
*mpio
;
409 union map_info
*info
;
410 struct request
*clone
, *n
;
413 spin_lock_irqsave(&m
->lock
, flags
);
414 list_splice_init(&m
->queued_ios
, &cl
);
415 spin_unlock_irqrestore(&m
->lock
, flags
);
417 list_for_each_entry_safe(clone
, n
, &cl
, queuelist
) {
418 list_del_init(&clone
->queuelist
);
420 info
= dm_get_rq_mapinfo(clone
);
423 r
= map_io(m
, clone
, mpio
, 1);
425 mempool_free(mpio
, m
->mpio_pool
);
426 dm_kill_unmapped_request(clone
, r
);
427 } else if (r
== DM_MAPIO_REMAPPED
)
428 dm_dispatch_request(clone
);
429 else if (r
== DM_MAPIO_REQUEUE
) {
430 mempool_free(mpio
, m
->mpio_pool
);
431 dm_requeue_unmapped_request(clone
);
436 static void process_queued_ios(struct work_struct
*work
)
438 struct multipath
*m
=
439 container_of(work
, struct multipath
, process_queued_ios
);
440 struct pgpath
*pgpath
= NULL
, *tmp
;
441 unsigned must_queue
= 1;
444 spin_lock_irqsave(&m
->lock
, flags
);
449 if (!m
->current_pgpath
)
450 __choose_pgpath(m
, 0);
452 pgpath
= m
->current_pgpath
;
454 if ((pgpath
&& !m
->queue_io
) ||
455 (!pgpath
&& !m
->queue_if_no_path
))
458 if (m
->pg_init_required
&& !m
->pg_init_in_progress
&& pgpath
) {
460 m
->pg_init_required
= 0;
461 list_for_each_entry(tmp
, &pgpath
->pg
->pgpaths
, list
) {
462 /* Skip failed paths */
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
)
589 struct multipath
*m
= ti
->private;
591 /* we need at least a path arg */
593 ti
->error
= "no device given";
594 return ERR_PTR(-EINVAL
);
599 return ERR_PTR(-ENOMEM
);
601 r
= dm_get_device(ti
, shift(as
), ti
->begin
, ti
->len
,
602 dm_table_get_mode(ti
->table
), &p
->path
.dev
);
604 ti
->error
= "error getting device";
608 if (m
->hw_handler_name
) {
609 struct request_queue
*q
= bdev_get_queue(p
->path
.dev
->bdev
);
611 r
= scsi_dh_attach(q
, m
->hw_handler_name
);
614 * Already attached to different hw_handler,
615 * try to reattach with correct one.
618 r
= scsi_dh_attach(q
, m
->hw_handler_name
);
622 ti
->error
= "error attaching hardware handler";
623 dm_put_device(ti
, p
->path
.dev
);
627 if (m
->hw_handler_params
) {
628 r
= scsi_dh_set_params(q
, m
->hw_handler_params
);
630 ti
->error
= "unable to set hardware "
631 "handler parameters";
633 dm_put_device(ti
, p
->path
.dev
);
639 r
= ps
->type
->add_path(ps
, &p
->path
, as
->argc
, as
->argv
, &ti
->error
);
641 dm_put_device(ti
, p
->path
.dev
);
652 static struct priority_group
*parse_priority_group(struct arg_set
*as
,
655 static struct param _params
[] = {
656 {1, 1024, "invalid number of paths"},
657 {0, 1024, "invalid number of selector args"}
661 unsigned i
, nr_selector_args
, nr_params
;
662 struct priority_group
*pg
;
663 struct dm_target
*ti
= m
->ti
;
667 ti
->error
= "not enough priority group arguments";
668 return ERR_PTR(-EINVAL
);
671 pg
= alloc_priority_group();
673 ti
->error
= "couldn't allocate priority group";
674 return ERR_PTR(-ENOMEM
);
678 r
= parse_path_selector(as
, pg
, ti
);
685 r
= read_param(_params
, shift(as
), &pg
->nr_pgpaths
, &ti
->error
);
689 r
= read_param(_params
+ 1, shift(as
), &nr_selector_args
, &ti
->error
);
693 nr_params
= 1 + nr_selector_args
;
694 for (i
= 0; i
< pg
->nr_pgpaths
; i
++) {
695 struct pgpath
*pgpath
;
696 struct arg_set path_args
;
698 if (as
->argc
< nr_params
) {
699 ti
->error
= "not enough path parameters";
703 path_args
.argc
= nr_params
;
704 path_args
.argv
= as
->argv
;
706 pgpath
= parse_path(&path_args
, &pg
->ps
, ti
);
707 if (IS_ERR(pgpath
)) {
713 list_add_tail(&pgpath
->list
, &pg
->pgpaths
);
714 consume(as
, nr_params
);
720 free_priority_group(pg
, ti
);
724 static int parse_hw_handler(struct arg_set
*as
, struct multipath
*m
)
728 struct dm_target
*ti
= m
->ti
;
730 static struct param _params
[] = {
731 {0, 1024, "invalid number of hardware handler args"},
734 if (read_param(_params
, shift(as
), &hw_argc
, &ti
->error
))
740 if (hw_argc
> as
->argc
) {
741 ti
->error
= "not enough arguments for hardware handler";
745 m
->hw_handler_name
= kstrdup(shift(as
), GFP_KERNEL
);
746 request_module("scsi_dh_%s", m
->hw_handler_name
);
747 if (scsi_dh_handler_exist(m
->hw_handler_name
) == 0) {
748 ti
->error
= "unknown hardware handler type";
757 for (i
= 0; i
<= hw_argc
- 2; i
++)
758 len
+= strlen(as
->argv
[i
]) + 1;
759 p
= m
->hw_handler_params
= kzalloc(len
, GFP_KERNEL
);
761 ti
->error
= "memory allocation failed";
765 j
= sprintf(p
, "%d", hw_argc
- 1);
766 for (i
= 0, p
+=j
+1; i
<= hw_argc
- 2; i
++, p
+=j
+1)
767 j
= sprintf(p
, "%s", as
->argv
[i
]);
769 consume(as
, hw_argc
- 1);
773 kfree(m
->hw_handler_name
);
774 m
->hw_handler_name
= NULL
;
778 static int parse_features(struct arg_set
*as
, struct multipath
*m
)
782 struct dm_target
*ti
= m
->ti
;
783 const char *param_name
;
785 static struct param _params
[] = {
786 {0, 3, "invalid number of feature args"},
787 {1, 50, "pg_init_retries must be between 1 and 50"},
790 r
= read_param(_params
, shift(as
), &argc
, &ti
->error
);
798 param_name
= shift(as
);
801 if (!strnicmp(param_name
, MESG_STR("queue_if_no_path"))) {
802 r
= queue_if_no_path(m
, 1, 0);
806 if (!strnicmp(param_name
, MESG_STR("pg_init_retries")) &&
808 r
= read_param(_params
+ 1, shift(as
),
809 &m
->pg_init_retries
, &ti
->error
);
814 ti
->error
= "Unrecognised multipath feature request";
816 } while (argc
&& !r
);
821 static int multipath_ctr(struct dm_target
*ti
, unsigned int argc
,
824 /* target parameters */
825 static struct param _params
[] = {
826 {1, 1024, "invalid number of priority groups"},
827 {1, 1024, "invalid initial priority group number"},
833 unsigned pg_count
= 0;
834 unsigned next_pg_num
;
839 m
= alloc_multipath(ti
);
841 ti
->error
= "can't allocate multipath";
845 r
= parse_features(&as
, m
);
849 r
= parse_hw_handler(&as
, m
);
853 r
= read_param(_params
, shift(&as
), &m
->nr_priority_groups
, &ti
->error
);
857 r
= read_param(_params
+ 1, shift(&as
), &next_pg_num
, &ti
->error
);
861 /* parse the priority groups */
863 struct priority_group
*pg
;
865 pg
= parse_priority_group(&as
, m
);
871 m
->nr_valid_paths
+= pg
->nr_pgpaths
;
872 list_add_tail(&pg
->list
, &m
->priority_groups
);
874 pg
->pg_num
= pg_count
;
879 if (pg_count
!= m
->nr_priority_groups
) {
880 ti
->error
= "priority group count mismatch";
885 ti
->num_flush_requests
= 1;
894 static void flush_multipath_work(void)
896 flush_workqueue(kmpath_handlerd
);
897 flush_workqueue(kmultipathd
);
898 flush_scheduled_work();
901 static void multipath_dtr(struct dm_target
*ti
)
903 struct multipath
*m
= ti
->private;
905 flush_multipath_work();
910 * Map cloned requests
912 static int multipath_map(struct dm_target
*ti
, struct request
*clone
,
913 union map_info
*map_context
)
916 struct dm_mpath_io
*mpio
;
917 struct multipath
*m
= (struct multipath
*) ti
->private;
919 mpio
= mempool_alloc(m
->mpio_pool
, GFP_ATOMIC
);
921 /* ENOMEM, requeue */
922 return DM_MAPIO_REQUEUE
;
923 memset(mpio
, 0, sizeof(*mpio
));
925 map_context
->ptr
= mpio
;
926 clone
->cmd_flags
|= REQ_FAILFAST_TRANSPORT
;
927 r
= map_io(m
, clone
, mpio
, 0);
928 if (r
< 0 || r
== DM_MAPIO_REQUEUE
)
929 mempool_free(mpio
, m
->mpio_pool
);
935 * Take a path out of use.
937 static int fail_path(struct pgpath
*pgpath
)
940 struct multipath
*m
= pgpath
->pg
->m
;
942 spin_lock_irqsave(&m
->lock
, flags
);
944 if (!pgpath
->is_active
)
947 DMWARN("Failing path %s.", pgpath
->path
.dev
->name
);
949 pgpath
->pg
->ps
.type
->fail_path(&pgpath
->pg
->ps
, &pgpath
->path
);
950 pgpath
->is_active
= 0;
951 pgpath
->fail_count
++;
955 if (pgpath
== m
->current_pgpath
)
956 m
->current_pgpath
= NULL
;
958 dm_path_uevent(DM_UEVENT_PATH_FAILED
, m
->ti
,
959 pgpath
->path
.dev
->name
, m
->nr_valid_paths
);
961 schedule_work(&m
->trigger_event
);
962 queue_work(kmultipathd
, &pgpath
->deactivate_path
);
965 spin_unlock_irqrestore(&m
->lock
, flags
);
971 * Reinstate a previously-failed path
973 static int reinstate_path(struct pgpath
*pgpath
)
977 struct multipath
*m
= pgpath
->pg
->m
;
979 spin_lock_irqsave(&m
->lock
, flags
);
981 if (pgpath
->is_active
)
984 if (!pgpath
->pg
->ps
.type
->reinstate_path
) {
985 DMWARN("Reinstate path not supported by path selector %s",
986 pgpath
->pg
->ps
.type
->name
);
991 r
= pgpath
->pg
->ps
.type
->reinstate_path(&pgpath
->pg
->ps
, &pgpath
->path
);
995 pgpath
->is_active
= 1;
997 if (!m
->nr_valid_paths
++ && m
->queue_size
) {
998 m
->current_pgpath
= NULL
;
999 queue_work(kmultipathd
, &m
->process_queued_ios
);
1000 } else if (m
->hw_handler_name
&& (m
->current_pg
== pgpath
->pg
)) {
1001 if (queue_work(kmpath_handlerd
, &pgpath
->activate_path
))
1002 m
->pg_init_in_progress
++;
1005 dm_path_uevent(DM_UEVENT_PATH_REINSTATED
, m
->ti
,
1006 pgpath
->path
.dev
->name
, m
->nr_valid_paths
);
1008 schedule_work(&m
->trigger_event
);
1011 spin_unlock_irqrestore(&m
->lock
, flags
);
1017 * Fail or reinstate all paths that match the provided struct dm_dev.
1019 static int action_dev(struct multipath
*m
, struct dm_dev
*dev
,
1023 struct pgpath
*pgpath
;
1024 struct priority_group
*pg
;
1026 list_for_each_entry(pg
, &m
->priority_groups
, list
) {
1027 list_for_each_entry(pgpath
, &pg
->pgpaths
, list
) {
1028 if (pgpath
->path
.dev
== dev
)
1037 * Temporarily try to avoid having to use the specified PG
1039 static void bypass_pg(struct multipath
*m
, struct priority_group
*pg
,
1042 unsigned long flags
;
1044 spin_lock_irqsave(&m
->lock
, flags
);
1046 pg
->bypassed
= bypassed
;
1047 m
->current_pgpath
= NULL
;
1048 m
->current_pg
= NULL
;
1050 spin_unlock_irqrestore(&m
->lock
, flags
);
1052 schedule_work(&m
->trigger_event
);
1056 * Switch to using the specified PG from the next I/O that gets mapped
1058 static int switch_pg_num(struct multipath
*m
, const char *pgstr
)
1060 struct priority_group
*pg
;
1062 unsigned long flags
;
1064 if (!pgstr
|| (sscanf(pgstr
, "%u", &pgnum
) != 1) || !pgnum
||
1065 (pgnum
> m
->nr_priority_groups
)) {
1066 DMWARN("invalid PG number supplied to switch_pg_num");
1070 spin_lock_irqsave(&m
->lock
, flags
);
1071 list_for_each_entry(pg
, &m
->priority_groups
, list
) {
1076 m
->current_pgpath
= NULL
;
1077 m
->current_pg
= NULL
;
1080 spin_unlock_irqrestore(&m
->lock
, flags
);
1082 schedule_work(&m
->trigger_event
);
1087 * Set/clear bypassed status of a PG.
1088 * PGs are numbered upwards from 1 in the order they were declared.
1090 static int bypass_pg_num(struct multipath
*m
, const char *pgstr
, int bypassed
)
1092 struct priority_group
*pg
;
1095 if (!pgstr
|| (sscanf(pgstr
, "%u", &pgnum
) != 1) || !pgnum
||
1096 (pgnum
> m
->nr_priority_groups
)) {
1097 DMWARN("invalid PG number supplied to bypass_pg");
1101 list_for_each_entry(pg
, &m
->priority_groups
, list
) {
1106 bypass_pg(m
, pg
, bypassed
);
1111 * Should we retry pg_init immediately?
1113 static int pg_init_limit_reached(struct multipath
*m
, struct pgpath
*pgpath
)
1115 unsigned long flags
;
1116 int limit_reached
= 0;
1118 spin_lock_irqsave(&m
->lock
, flags
);
1120 if (m
->pg_init_count
<= m
->pg_init_retries
)
1121 m
->pg_init_required
= 1;
1125 spin_unlock_irqrestore(&m
->lock
, flags
);
1127 return limit_reached
;
1130 static void pg_init_done(void *data
, int errors
)
1132 struct pgpath
*pgpath
= data
;
1133 struct priority_group
*pg
= pgpath
->pg
;
1134 struct multipath
*m
= pg
->m
;
1135 unsigned long flags
;
1137 /* device or driver problems */
1142 if (!m
->hw_handler_name
) {
1146 DMERR("Could not failover the device: Handler scsi_dh_%s "
1147 "Error %d.", m
->hw_handler_name
, errors
);
1149 * Fail path for now, so we do not ping pong
1153 case SCSI_DH_DEV_TEMP_BUSY
:
1155 * Probably doing something like FW upgrade on the
1156 * controller so try the other pg.
1158 bypass_pg(m
, pg
, 1);
1160 /* TODO: For SCSI_DH_RETRY we should wait a couple seconds */
1162 case SCSI_DH_IMM_RETRY
:
1163 case SCSI_DH_RES_TEMP_UNAVAIL
:
1164 if (pg_init_limit_reached(m
, pgpath
))
1170 * We probably do not want to fail the path for a device
1171 * error, but this is what the old dm did. In future
1172 * patches we can do more advanced handling.
1177 spin_lock_irqsave(&m
->lock
, flags
);
1179 if (pgpath
== m
->current_pgpath
) {
1180 DMERR("Could not failover device. Error %d.", errors
);
1181 m
->current_pgpath
= NULL
;
1182 m
->current_pg
= NULL
;
1184 } else if (!m
->pg_init_required
)
1187 if (--m
->pg_init_in_progress
)
1188 /* Activations of other paths are still on going */
1191 if (!m
->pg_init_required
)
1194 queue_work(kmultipathd
, &m
->process_queued_ios
);
1197 spin_unlock_irqrestore(&m
->lock
, flags
);
1200 static void activate_path(struct work_struct
*work
)
1202 struct pgpath
*pgpath
=
1203 container_of(work
, struct pgpath
, activate_path
);
1205 scsi_dh_activate(bdev_get_queue(pgpath
->path
.dev
->bdev
),
1206 pg_init_done
, pgpath
);
1212 static int do_end_io(struct multipath
*m
, struct request
*clone
,
1213 int error
, struct dm_mpath_io
*mpio
)
1216 * We don't queue any clone request inside the multipath target
1217 * during end I/O handling, since those clone requests don't have
1218 * bio clones. If we queue them inside the multipath target,
1219 * we need to make bio clones, that requires memory allocation.
1220 * (See drivers/md/dm.c:end_clone_bio() about why the clone requests
1221 * don't have bio clones.)
1222 * Instead of queueing the clone request here, we queue the original
1223 * request into dm core, which will remake a clone request and
1224 * clone bios for it and resubmit it later.
1226 int r
= DM_ENDIO_REQUEUE
;
1227 unsigned long flags
;
1229 if (!error
&& !clone
->errors
)
1230 return 0; /* I/O complete */
1232 if (error
== -EOPNOTSUPP
)
1236 fail_path(mpio
->pgpath
);
1238 spin_lock_irqsave(&m
->lock
, flags
);
1239 if (!m
->nr_valid_paths
&& !m
->queue_if_no_path
&& !__must_push_back(m
))
1241 spin_unlock_irqrestore(&m
->lock
, flags
);
1246 static int multipath_end_io(struct dm_target
*ti
, struct request
*clone
,
1247 int error
, union map_info
*map_context
)
1249 struct multipath
*m
= ti
->private;
1250 struct dm_mpath_io
*mpio
= map_context
->ptr
;
1251 struct pgpath
*pgpath
= mpio
->pgpath
;
1252 struct path_selector
*ps
;
1255 r
= do_end_io(m
, clone
, error
, mpio
);
1257 ps
= &pgpath
->pg
->ps
;
1258 if (ps
->type
->end_io
)
1259 ps
->type
->end_io(ps
, &pgpath
->path
, mpio
->nr_bytes
);
1261 mempool_free(mpio
, m
->mpio_pool
);
1267 * Suspend can't complete until all the I/O is processed so if
1268 * the last path fails we must error any remaining I/O.
1269 * Note that if the freeze_bdev fails while suspending, the
1270 * queue_if_no_path state is lost - userspace should reset it.
1272 static void multipath_presuspend(struct dm_target
*ti
)
1274 struct multipath
*m
= (struct multipath
*) ti
->private;
1276 queue_if_no_path(m
, 0, 1);
1279 static void multipath_postsuspend(struct dm_target
*ti
)
1281 struct multipath
*m
= ti
->private;
1283 mutex_lock(&m
->work_mutex
);
1284 flush_multipath_work();
1285 mutex_unlock(&m
->work_mutex
);
1289 * Restore the queue_if_no_path setting.
1291 static void multipath_resume(struct dm_target
*ti
)
1293 struct multipath
*m
= (struct multipath
*) ti
->private;
1294 unsigned long flags
;
1296 spin_lock_irqsave(&m
->lock
, flags
);
1297 m
->queue_if_no_path
= m
->saved_queue_if_no_path
;
1298 spin_unlock_irqrestore(&m
->lock
, flags
);
1302 * Info output has the following format:
1303 * num_multipath_feature_args [multipath_feature_args]*
1304 * num_handler_status_args [handler_status_args]*
1305 * num_groups init_group_number
1306 * [A|D|E num_ps_status_args [ps_status_args]*
1307 * num_paths num_selector_args
1308 * [path_dev A|F fail_count [selector_args]* ]+ ]+
1310 * Table output has the following format (identical to the constructor string):
1311 * num_feature_args [features_args]*
1312 * num_handler_args hw_handler [hw_handler_args]*
1313 * num_groups init_group_number
1314 * [priority selector-name num_ps_args [ps_args]*
1315 * num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
1317 static int multipath_status(struct dm_target
*ti
, status_type_t type
,
1318 char *result
, unsigned int maxlen
)
1321 unsigned long flags
;
1322 struct multipath
*m
= (struct multipath
*) ti
->private;
1323 struct priority_group
*pg
;
1328 spin_lock_irqsave(&m
->lock
, flags
);
1331 if (type
== STATUSTYPE_INFO
)
1332 DMEMIT("2 %u %u ", m
->queue_size
, m
->pg_init_count
);
1334 DMEMIT("%u ", m
->queue_if_no_path
+
1335 (m
->pg_init_retries
> 0) * 2);
1336 if (m
->queue_if_no_path
)
1337 DMEMIT("queue_if_no_path ");
1338 if (m
->pg_init_retries
)
1339 DMEMIT("pg_init_retries %u ", m
->pg_init_retries
);
1342 if (!m
->hw_handler_name
|| type
== STATUSTYPE_INFO
)
1345 DMEMIT("1 %s ", m
->hw_handler_name
);
1347 DMEMIT("%u ", m
->nr_priority_groups
);
1350 pg_num
= m
->next_pg
->pg_num
;
1351 else if (m
->current_pg
)
1352 pg_num
= m
->current_pg
->pg_num
;
1356 DMEMIT("%u ", pg_num
);
1359 case STATUSTYPE_INFO
:
1360 list_for_each_entry(pg
, &m
->priority_groups
, list
) {
1362 state
= 'D'; /* Disabled */
1363 else if (pg
== m
->current_pg
)
1364 state
= 'A'; /* Currently Active */
1366 state
= 'E'; /* Enabled */
1368 DMEMIT("%c ", state
);
1370 if (pg
->ps
.type
->status
)
1371 sz
+= pg
->ps
.type
->status(&pg
->ps
, NULL
, type
,
1377 DMEMIT("%u %u ", pg
->nr_pgpaths
,
1378 pg
->ps
.type
->info_args
);
1380 list_for_each_entry(p
, &pg
->pgpaths
, list
) {
1381 DMEMIT("%s %s %u ", p
->path
.dev
->name
,
1382 p
->is_active
? "A" : "F",
1384 if (pg
->ps
.type
->status
)
1385 sz
+= pg
->ps
.type
->status(&pg
->ps
,
1386 &p
->path
, type
, result
+ sz
,
1392 case STATUSTYPE_TABLE
:
1393 list_for_each_entry(pg
, &m
->priority_groups
, list
) {
1394 DMEMIT("%s ", pg
->ps
.type
->name
);
1396 if (pg
->ps
.type
->status
)
1397 sz
+= pg
->ps
.type
->status(&pg
->ps
, NULL
, type
,
1403 DMEMIT("%u %u ", pg
->nr_pgpaths
,
1404 pg
->ps
.type
->table_args
);
1406 list_for_each_entry(p
, &pg
->pgpaths
, list
) {
1407 DMEMIT("%s ", p
->path
.dev
->name
);
1408 if (pg
->ps
.type
->status
)
1409 sz
+= pg
->ps
.type
->status(&pg
->ps
,
1410 &p
->path
, type
, result
+ sz
,
1417 spin_unlock_irqrestore(&m
->lock
, flags
);
1422 static int multipath_message(struct dm_target
*ti
, unsigned argc
, char **argv
)
1426 struct multipath
*m
= (struct multipath
*) ti
->private;
1429 mutex_lock(&m
->work_mutex
);
1431 if (dm_suspended(ti
)) {
1437 if (!strnicmp(argv
[0], MESG_STR("queue_if_no_path"))) {
1438 r
= queue_if_no_path(m
, 1, 0);
1440 } else if (!strnicmp(argv
[0], MESG_STR("fail_if_no_path"))) {
1441 r
= queue_if_no_path(m
, 0, 0);
1447 DMWARN("Unrecognised multipath message received.");
1451 if (!strnicmp(argv
[0], MESG_STR("disable_group"))) {
1452 r
= bypass_pg_num(m
, argv
[1], 1);
1454 } else if (!strnicmp(argv
[0], MESG_STR("enable_group"))) {
1455 r
= bypass_pg_num(m
, argv
[1], 0);
1457 } else if (!strnicmp(argv
[0], MESG_STR("switch_group"))) {
1458 r
= switch_pg_num(m
, argv
[1]);
1460 } else if (!strnicmp(argv
[0], MESG_STR("reinstate_path")))
1461 action
= reinstate_path
;
1462 else if (!strnicmp(argv
[0], MESG_STR("fail_path")))
1465 DMWARN("Unrecognised multipath message received.");
1469 r
= dm_get_device(ti
, argv
[1], ti
->begin
, ti
->len
,
1470 dm_table_get_mode(ti
->table
), &dev
);
1472 DMWARN("message: error getting device %s",
1477 r
= action_dev(m
, dev
, action
);
1479 dm_put_device(ti
, dev
);
1482 mutex_unlock(&m
->work_mutex
);
1486 static int multipath_ioctl(struct dm_target
*ti
, unsigned int cmd
,
1489 struct multipath
*m
= (struct multipath
*) ti
->private;
1490 struct block_device
*bdev
= NULL
;
1492 unsigned long flags
;
1495 spin_lock_irqsave(&m
->lock
, flags
);
1497 if (!m
->current_pgpath
)
1498 __choose_pgpath(m
, 0);
1500 if (m
->current_pgpath
) {
1501 bdev
= m
->current_pgpath
->path
.dev
->bdev
;
1502 mode
= m
->current_pgpath
->path
.dev
->mode
;
1510 spin_unlock_irqrestore(&m
->lock
, flags
);
1512 return r
? : __blkdev_driver_ioctl(bdev
, mode
, cmd
, arg
);
1515 static int multipath_iterate_devices(struct dm_target
*ti
,
1516 iterate_devices_callout_fn fn
, void *data
)
1518 struct multipath
*m
= ti
->private;
1519 struct priority_group
*pg
;
1523 list_for_each_entry(pg
, &m
->priority_groups
, list
) {
1524 list_for_each_entry(p
, &pg
->pgpaths
, list
) {
1525 ret
= fn(ti
, p
->path
.dev
, ti
->begin
, ti
->len
, data
);
1535 static int __pgpath_busy(struct pgpath
*pgpath
)
1537 struct request_queue
*q
= bdev_get_queue(pgpath
->path
.dev
->bdev
);
1539 return dm_underlying_device_busy(q
);
1543 * We return "busy", only when we can map I/Os but underlying devices
1544 * are busy (so even if we map I/Os now, the I/Os will wait on
1545 * the underlying queue).
1546 * In other words, if we want to kill I/Os or queue them inside us
1547 * due to map unavailability, we don't return "busy". Otherwise,
1548 * dm core won't give us the I/Os and we can't do what we want.
1550 static int multipath_busy(struct dm_target
*ti
)
1552 int busy
= 0, has_active
= 0;
1553 struct multipath
*m
= ti
->private;
1554 struct priority_group
*pg
;
1555 struct pgpath
*pgpath
;
1556 unsigned long flags
;
1558 spin_lock_irqsave(&m
->lock
, flags
);
1560 /* Guess which priority_group will be used at next mapping time */
1561 if (unlikely(!m
->current_pgpath
&& m
->next_pg
))
1563 else if (likely(m
->current_pg
))
1567 * We don't know which pg will be used at next mapping time.
1568 * We don't call __choose_pgpath() here to avoid to trigger
1569 * pg_init just by busy checking.
1570 * So we don't know whether underlying devices we will be using
1571 * at next mapping time are busy or not. Just try mapping.
1576 * If there is one non-busy active path at least, the path selector
1577 * will be able to select it. So we consider such a pg as not busy.
1580 list_for_each_entry(pgpath
, &pg
->pgpaths
, list
)
1581 if (pgpath
->is_active
) {
1584 if (!__pgpath_busy(pgpath
)) {
1592 * No active path in this pg, so this pg won't be used and
1593 * the current_pg will be changed at next mapping time.
1594 * We need to try mapping to determine it.
1599 spin_unlock_irqrestore(&m
->lock
, flags
);
1604 /*-----------------------------------------------------------------
1606 *---------------------------------------------------------------*/
1607 static struct target_type multipath_target
= {
1608 .name
= "multipath",
1609 .version
= {1, 1, 1},
1610 .module
= THIS_MODULE
,
1611 .ctr
= multipath_ctr
,
1612 .dtr
= multipath_dtr
,
1613 .map_rq
= multipath_map
,
1614 .rq_end_io
= multipath_end_io
,
1615 .presuspend
= multipath_presuspend
,
1616 .postsuspend
= multipath_postsuspend
,
1617 .resume
= multipath_resume
,
1618 .status
= multipath_status
,
1619 .message
= multipath_message
,
1620 .ioctl
= multipath_ioctl
,
1621 .iterate_devices
= multipath_iterate_devices
,
1622 .busy
= multipath_busy
,
1625 static int __init
dm_multipath_init(void)
1629 /* allocate a slab for the dm_ios */
1630 _mpio_cache
= KMEM_CACHE(dm_mpath_io
, 0);
1634 r
= dm_register_target(&multipath_target
);
1636 DMERR("register failed %d", r
);
1637 kmem_cache_destroy(_mpio_cache
);
1641 kmultipathd
= create_workqueue("kmpathd");
1643 DMERR("failed to create workqueue kmpathd");
1644 dm_unregister_target(&multipath_target
);
1645 kmem_cache_destroy(_mpio_cache
);
1650 * A separate workqueue is used to handle the device handlers
1651 * to avoid overloading existing workqueue. Overloading the
1652 * old workqueue would also create a bottleneck in the
1653 * path of the storage hardware device activation.
1655 kmpath_handlerd
= create_singlethread_workqueue("kmpath_handlerd");
1656 if (!kmpath_handlerd
) {
1657 DMERR("failed to create workqueue kmpath_handlerd");
1658 destroy_workqueue(kmultipathd
);
1659 dm_unregister_target(&multipath_target
);
1660 kmem_cache_destroy(_mpio_cache
);
1664 DMINFO("version %u.%u.%u loaded",
1665 multipath_target
.version
[0], multipath_target
.version
[1],
1666 multipath_target
.version
[2]);
1671 static void __exit
dm_multipath_exit(void)
1673 destroy_workqueue(kmpath_handlerd
);
1674 destroy_workqueue(kmultipathd
);
1676 dm_unregister_target(&multipath_target
);
1677 kmem_cache_destroy(_mpio_cache
);
1680 module_init(dm_multipath_init
);
1681 module_exit(dm_multipath_exit
);
1683 MODULE_DESCRIPTION(DM_NAME
" multipath target");
1684 MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
1685 MODULE_LICENSE("GPL");