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>
11 #include "dm-bio-record.h"
12 #include "dm-path-selector.h"
13 #include "dm-uevent.h"
15 #include <linux/blkdev.h>
16 #include <linux/ctype.h>
17 #include <linux/init.h>
18 #include <linux/mempool.h>
19 #include <linux/module.h>
20 #include <linux/pagemap.h>
21 #include <linux/slab.h>
22 #include <linux/time.h>
23 #include <linux/workqueue.h>
24 #include <linux/delay.h>
25 #include <scsi/scsi_dh.h>
26 #include <linux/atomic.h>
27 #include <linux/blk-mq.h>
29 #define DM_MSG_PREFIX "multipath"
30 #define DM_PG_INIT_DELAY_MSECS 2000
31 #define DM_PG_INIT_DELAY_DEFAULT ((unsigned) -1)
35 struct list_head list
;
37 struct priority_group
*pg
; /* Owning PG */
38 unsigned fail_count
; /* Cumulative failure count */
41 struct delayed_work activate_path
;
43 bool is_active
:1; /* Path status */
46 #define path_to_pgpath(__pgp) container_of((__pgp), struct pgpath, path)
49 * Paths are grouped into Priority Groups and numbered from 1 upwards.
50 * Each has a path selector which controls which path gets used.
52 struct priority_group
{
53 struct list_head list
;
55 struct multipath
*m
; /* Owning multipath instance */
56 struct path_selector ps
;
58 unsigned pg_num
; /* Reference number */
59 unsigned nr_pgpaths
; /* Number of paths in PG */
60 struct list_head pgpaths
;
62 bool bypassed
:1; /* Temporarily bypass this PG? */
65 /* Multipath context */
67 struct list_head list
;
70 const char *hw_handler_name
;
71 char *hw_handler_params
;
75 unsigned nr_priority_groups
;
76 struct list_head priority_groups
;
78 wait_queue_head_t pg_init_wait
; /* Wait for pg_init completion */
80 struct pgpath
*current_pgpath
;
81 struct priority_group
*current_pg
;
82 struct priority_group
*next_pg
; /* Switch to this PG if set */
84 unsigned long flags
; /* Multipath state flags */
86 unsigned pg_init_retries
; /* Number of times to retry pg_init */
87 unsigned pg_init_delay_msecs
; /* Number of msecs before pg_init retry */
89 atomic_t nr_valid_paths
; /* Total number of usable paths */
90 atomic_t pg_init_in_progress
; /* Only one pg_init allowed at once */
91 atomic_t pg_init_count
; /* Number of times pg_init called */
96 * We must use a mempool of dm_mpath_io structs so that we
97 * can resubmit bios on error.
101 struct mutex work_mutex
;
102 struct work_struct trigger_event
;
104 struct work_struct process_queued_bios
;
105 struct bio_list queued_bios
;
109 * Context information attached to each io we process.
112 struct pgpath
*pgpath
;
116 typedef int (*action_fn
) (struct pgpath
*pgpath
);
118 static struct kmem_cache
*_mpio_cache
;
120 static struct workqueue_struct
*kmultipathd
, *kmpath_handlerd
;
121 static void trigger_event(struct work_struct
*work
);
122 static void activate_path(struct work_struct
*work
);
123 static void process_queued_bios(struct work_struct
*work
);
125 /*-----------------------------------------------
126 * Multipath state flags.
127 *-----------------------------------------------*/
129 #define MPATHF_QUEUE_IO 0 /* Must we queue all I/O? */
130 #define MPATHF_QUEUE_IF_NO_PATH 1 /* Queue I/O if last path fails? */
131 #define MPATHF_SAVED_QUEUE_IF_NO_PATH 2 /* Saved state during suspension */
132 #define MPATHF_RETAIN_ATTACHED_HW_HANDLER 3 /* If there's already a hw_handler present, don't change it. */
133 #define MPATHF_PG_INIT_DISABLED 4 /* pg_init is not currently allowed */
134 #define MPATHF_PG_INIT_REQUIRED 5 /* pg_init needs calling? */
135 #define MPATHF_PG_INIT_DELAY_RETRY 6 /* Delay pg_init retry? */
137 /*-----------------------------------------------
138 * Allocation routines
139 *-----------------------------------------------*/
141 static struct pgpath
*alloc_pgpath(void)
143 struct pgpath
*pgpath
= kzalloc(sizeof(*pgpath
), GFP_KERNEL
);
146 pgpath
->is_active
= true;
147 INIT_DELAYED_WORK(&pgpath
->activate_path
, activate_path
);
153 static void free_pgpath(struct pgpath
*pgpath
)
158 static struct priority_group
*alloc_priority_group(void)
160 struct priority_group
*pg
;
162 pg
= kzalloc(sizeof(*pg
), GFP_KERNEL
);
165 INIT_LIST_HEAD(&pg
->pgpaths
);
170 static void free_pgpaths(struct list_head
*pgpaths
, struct dm_target
*ti
)
172 struct pgpath
*pgpath
, *tmp
;
174 list_for_each_entry_safe(pgpath
, tmp
, pgpaths
, list
) {
175 list_del(&pgpath
->list
);
176 dm_put_device(ti
, pgpath
->path
.dev
);
181 static void free_priority_group(struct priority_group
*pg
,
182 struct dm_target
*ti
)
184 struct path_selector
*ps
= &pg
->ps
;
187 ps
->type
->destroy(ps
);
188 dm_put_path_selector(ps
->type
);
191 free_pgpaths(&pg
->pgpaths
, ti
);
195 static struct multipath
*alloc_multipath(struct dm_target
*ti
)
199 m
= kzalloc(sizeof(*m
), GFP_KERNEL
);
201 INIT_LIST_HEAD(&m
->priority_groups
);
202 spin_lock_init(&m
->lock
);
203 set_bit(MPATHF_QUEUE_IO
, &m
->flags
);
204 atomic_set(&m
->nr_valid_paths
, 0);
205 atomic_set(&m
->pg_init_in_progress
, 0);
206 atomic_set(&m
->pg_init_count
, 0);
207 m
->pg_init_delay_msecs
= DM_PG_INIT_DELAY_DEFAULT
;
208 INIT_WORK(&m
->trigger_event
, trigger_event
);
209 init_waitqueue_head(&m
->pg_init_wait
);
210 mutex_init(&m
->work_mutex
);
213 m
->queue_mode
= DM_TYPE_NONE
;
222 static int alloc_multipath_stage2(struct dm_target
*ti
, struct multipath
*m
)
224 if (m
->queue_mode
== DM_TYPE_NONE
) {
226 * Default to request-based.
228 if (dm_use_blk_mq(dm_table_get_md(ti
->table
)))
229 m
->queue_mode
= DM_TYPE_MQ_REQUEST_BASED
;
231 m
->queue_mode
= DM_TYPE_REQUEST_BASED
;
234 if (m
->queue_mode
== DM_TYPE_REQUEST_BASED
) {
235 unsigned min_ios
= dm_get_reserved_rq_based_ios();
237 m
->mpio_pool
= mempool_create_slab_pool(min_ios
, _mpio_cache
);
241 else if (m
->queue_mode
== DM_TYPE_BIO_BASED
) {
242 INIT_WORK(&m
->process_queued_bios
, process_queued_bios
);
244 * bio-based doesn't support any direct scsi_dh management;
245 * it just discovers if a scsi_dh is attached.
247 set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER
, &m
->flags
);
250 dm_table_set_type(ti
->table
, m
->queue_mode
);
255 static void free_multipath(struct multipath
*m
)
257 struct priority_group
*pg
, *tmp
;
259 list_for_each_entry_safe(pg
, tmp
, &m
->priority_groups
, list
) {
261 free_priority_group(pg
, m
->ti
);
264 kfree(m
->hw_handler_name
);
265 kfree(m
->hw_handler_params
);
266 mempool_destroy(m
->mpio_pool
);
270 static struct dm_mpath_io
*get_mpio(union map_info
*info
)
275 static struct dm_mpath_io
*set_mpio(struct multipath
*m
, union map_info
*info
)
277 struct dm_mpath_io
*mpio
;
280 /* Use blk-mq pdu memory requested via per_io_data_size */
281 mpio
= get_mpio(info
);
282 memset(mpio
, 0, sizeof(*mpio
));
286 mpio
= mempool_alloc(m
->mpio_pool
, GFP_ATOMIC
);
290 memset(mpio
, 0, sizeof(*mpio
));
296 static void clear_request_fn_mpio(struct multipath
*m
, union map_info
*info
)
298 /* Only needed for non blk-mq (.request_fn) multipath */
300 struct dm_mpath_io
*mpio
= info
->ptr
;
303 mempool_free(mpio
, m
->mpio_pool
);
307 static size_t multipath_per_bio_data_size(void)
309 return sizeof(struct dm_mpath_io
) + sizeof(struct dm_bio_details
);
312 static struct dm_mpath_io
*get_mpio_from_bio(struct bio
*bio
)
314 return dm_per_bio_data(bio
, multipath_per_bio_data_size());
317 static struct dm_bio_details
*get_bio_details_from_bio(struct bio
*bio
)
319 /* dm_bio_details is immediately after the dm_mpath_io in bio's per-bio-data */
320 struct dm_mpath_io
*mpio
= get_mpio_from_bio(bio
);
321 void *bio_details
= mpio
+ 1;
326 static void multipath_init_per_bio_data(struct bio
*bio
, struct dm_mpath_io
**mpio_p
,
327 struct dm_bio_details
**bio_details_p
)
329 struct dm_mpath_io
*mpio
= get_mpio_from_bio(bio
);
330 struct dm_bio_details
*bio_details
= get_bio_details_from_bio(bio
);
332 memset(mpio
, 0, sizeof(*mpio
));
333 memset(bio_details
, 0, sizeof(*bio_details
));
334 dm_bio_record(bio_details
, bio
);
339 *bio_details_p
= bio_details
;
342 /*-----------------------------------------------
344 *-----------------------------------------------*/
346 static int __pg_init_all_paths(struct multipath
*m
)
348 struct pgpath
*pgpath
;
349 unsigned long pg_init_delay
= 0;
351 if (atomic_read(&m
->pg_init_in_progress
) || test_bit(MPATHF_PG_INIT_DISABLED
, &m
->flags
))
354 atomic_inc(&m
->pg_init_count
);
355 clear_bit(MPATHF_PG_INIT_REQUIRED
, &m
->flags
);
357 /* Check here to reset pg_init_required */
361 if (test_bit(MPATHF_PG_INIT_DELAY_RETRY
, &m
->flags
))
362 pg_init_delay
= msecs_to_jiffies(m
->pg_init_delay_msecs
!= DM_PG_INIT_DELAY_DEFAULT
?
363 m
->pg_init_delay_msecs
: DM_PG_INIT_DELAY_MSECS
);
364 list_for_each_entry(pgpath
, &m
->current_pg
->pgpaths
, list
) {
365 /* Skip failed paths */
366 if (!pgpath
->is_active
)
368 if (queue_delayed_work(kmpath_handlerd
, &pgpath
->activate_path
,
370 atomic_inc(&m
->pg_init_in_progress
);
372 return atomic_read(&m
->pg_init_in_progress
);
375 static int pg_init_all_paths(struct multipath
*m
)
380 spin_lock_irqsave(&m
->lock
, flags
);
381 r
= __pg_init_all_paths(m
);
382 spin_unlock_irqrestore(&m
->lock
, flags
);
387 static void __switch_pg(struct multipath
*m
, struct priority_group
*pg
)
391 /* Must we initialise the PG first, and queue I/O till it's ready? */
392 if (m
->hw_handler_name
) {
393 set_bit(MPATHF_PG_INIT_REQUIRED
, &m
->flags
);
394 set_bit(MPATHF_QUEUE_IO
, &m
->flags
);
396 clear_bit(MPATHF_PG_INIT_REQUIRED
, &m
->flags
);
397 clear_bit(MPATHF_QUEUE_IO
, &m
->flags
);
400 atomic_set(&m
->pg_init_count
, 0);
403 static struct pgpath
*choose_path_in_pg(struct multipath
*m
,
404 struct priority_group
*pg
,
408 struct dm_path
*path
;
409 struct pgpath
*pgpath
;
411 path
= pg
->ps
.type
->select_path(&pg
->ps
, nr_bytes
);
413 return ERR_PTR(-ENXIO
);
415 pgpath
= path_to_pgpath(path
);
417 if (unlikely(lockless_dereference(m
->current_pg
) != pg
)) {
418 /* Only update current_pgpath if pg changed */
419 spin_lock_irqsave(&m
->lock
, flags
);
420 m
->current_pgpath
= pgpath
;
422 spin_unlock_irqrestore(&m
->lock
, flags
);
428 static struct pgpath
*choose_pgpath(struct multipath
*m
, size_t nr_bytes
)
431 struct priority_group
*pg
;
432 struct pgpath
*pgpath
;
433 bool bypassed
= true;
435 if (!atomic_read(&m
->nr_valid_paths
)) {
436 clear_bit(MPATHF_QUEUE_IO
, &m
->flags
);
440 /* Were we instructed to switch PG? */
441 if (lockless_dereference(m
->next_pg
)) {
442 spin_lock_irqsave(&m
->lock
, flags
);
445 spin_unlock_irqrestore(&m
->lock
, flags
);
446 goto check_current_pg
;
449 spin_unlock_irqrestore(&m
->lock
, flags
);
450 pgpath
= choose_path_in_pg(m
, pg
, nr_bytes
);
451 if (!IS_ERR_OR_NULL(pgpath
))
455 /* Don't change PG until it has no remaining paths */
457 pg
= lockless_dereference(m
->current_pg
);
459 pgpath
= choose_path_in_pg(m
, pg
, nr_bytes
);
460 if (!IS_ERR_OR_NULL(pgpath
))
465 * Loop through priority groups until we find a valid path.
466 * First time we skip PGs marked 'bypassed'.
467 * Second time we only try the ones we skipped, but set
468 * pg_init_delay_retry so we do not hammer controllers.
471 list_for_each_entry(pg
, &m
->priority_groups
, list
) {
472 if (pg
->bypassed
== bypassed
)
474 pgpath
= choose_path_in_pg(m
, pg
, nr_bytes
);
475 if (!IS_ERR_OR_NULL(pgpath
)) {
477 set_bit(MPATHF_PG_INIT_DELAY_RETRY
, &m
->flags
);
481 } while (bypassed
--);
484 spin_lock_irqsave(&m
->lock
, flags
);
485 m
->current_pgpath
= NULL
;
486 m
->current_pg
= NULL
;
487 spin_unlock_irqrestore(&m
->lock
, flags
);
493 * Check whether bios must be queued in the device-mapper core rather
494 * than here in the target.
496 * If m->queue_if_no_path and m->saved_queue_if_no_path hold the
497 * same value then we are not between multipath_presuspend()
498 * and multipath_resume() calls and we have no need to check
499 * for the DMF_NOFLUSH_SUSPENDING flag.
501 static bool __must_push_back(struct multipath
*m
)
503 return ((test_bit(MPATHF_QUEUE_IF_NO_PATH
, &m
->flags
) !=
504 test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH
, &m
->flags
)) &&
505 dm_noflush_suspending(m
->ti
));
508 static bool must_push_back_rq(struct multipath
*m
)
513 spin_lock_irqsave(&m
->lock
, flags
);
514 r
= (test_bit(MPATHF_QUEUE_IF_NO_PATH
, &m
->flags
) ||
515 __must_push_back(m
));
516 spin_unlock_irqrestore(&m
->lock
, flags
);
521 static bool must_push_back_bio(struct multipath
*m
)
526 spin_lock_irqsave(&m
->lock
, flags
);
527 r
= __must_push_back(m
);
528 spin_unlock_irqrestore(&m
->lock
, flags
);
534 * Map cloned requests (request-based multipath)
536 static int __multipath_map(struct dm_target
*ti
, struct request
*clone
,
537 union map_info
*map_context
,
538 struct request
*rq
, struct request
**__clone
)
540 struct multipath
*m
= ti
->private;
541 int r
= DM_MAPIO_REQUEUE
;
542 size_t nr_bytes
= clone
? blk_rq_bytes(clone
) : blk_rq_bytes(rq
);
543 struct pgpath
*pgpath
;
544 struct block_device
*bdev
;
545 struct dm_mpath_io
*mpio
;
547 /* Do we need to select a new pgpath? */
548 pgpath
= lockless_dereference(m
->current_pgpath
);
549 if (!pgpath
|| !test_bit(MPATHF_QUEUE_IO
, &m
->flags
))
550 pgpath
= choose_pgpath(m
, nr_bytes
);
553 if (!must_push_back_rq(m
))
554 r
= -EIO
; /* Failed */
556 } else if (test_bit(MPATHF_QUEUE_IO
, &m
->flags
) ||
557 test_bit(MPATHF_PG_INIT_REQUIRED
, &m
->flags
)) {
558 pg_init_all_paths(m
);
562 mpio
= set_mpio(m
, map_context
);
564 /* ENOMEM, requeue */
567 mpio
->pgpath
= pgpath
;
568 mpio
->nr_bytes
= nr_bytes
;
570 bdev
= pgpath
->path
.dev
->bdev
;
574 * Old request-based interface: allocated clone is passed in.
575 * Used by: .request_fn stacked on .request_fn path(s).
577 clone
->q
= bdev_get_queue(bdev
);
578 clone
->rq_disk
= bdev
->bd_disk
;
579 clone
->cmd_flags
|= REQ_FAILFAST_TRANSPORT
;
582 * blk-mq request-based interface; used by both:
583 * .request_fn stacked on blk-mq path(s) and
584 * blk-mq stacked on blk-mq path(s).
586 *__clone
= blk_mq_alloc_request(bdev_get_queue(bdev
),
587 rq_data_dir(rq
), BLK_MQ_REQ_NOWAIT
);
588 if (IS_ERR(*__clone
)) {
589 /* ENOMEM, requeue */
590 clear_request_fn_mpio(m
, map_context
);
593 (*__clone
)->bio
= (*__clone
)->biotail
= NULL
;
594 (*__clone
)->rq_disk
= bdev
->bd_disk
;
595 (*__clone
)->cmd_flags
|= REQ_FAILFAST_TRANSPORT
;
598 if (pgpath
->pg
->ps
.type
->start_io
)
599 pgpath
->pg
->ps
.type
->start_io(&pgpath
->pg
->ps
,
602 return DM_MAPIO_REMAPPED
;
605 static int multipath_map(struct dm_target
*ti
, struct request
*clone
,
606 union map_info
*map_context
)
608 return __multipath_map(ti
, clone
, map_context
, NULL
, NULL
);
611 static int multipath_clone_and_map(struct dm_target
*ti
, struct request
*rq
,
612 union map_info
*map_context
,
613 struct request
**clone
)
615 return __multipath_map(ti
, NULL
, map_context
, rq
, clone
);
618 static void multipath_release_clone(struct request
*clone
)
620 blk_mq_free_request(clone
);
624 * Map cloned bios (bio-based multipath)
626 static int __multipath_map_bio(struct multipath
*m
, struct bio
*bio
, struct dm_mpath_io
*mpio
)
628 size_t nr_bytes
= bio
->bi_iter
.bi_size
;
629 struct pgpath
*pgpath
;
633 /* Do we need to select a new pgpath? */
634 pgpath
= lockless_dereference(m
->current_pgpath
);
635 queue_io
= test_bit(MPATHF_QUEUE_IO
, &m
->flags
);
636 if (!pgpath
|| !queue_io
)
637 pgpath
= choose_pgpath(m
, nr_bytes
);
639 if ((pgpath
&& queue_io
) ||
640 (!pgpath
&& test_bit(MPATHF_QUEUE_IF_NO_PATH
, &m
->flags
))) {
641 /* Queue for the daemon to resubmit */
642 spin_lock_irqsave(&m
->lock
, flags
);
643 bio_list_add(&m
->queued_bios
, bio
);
644 spin_unlock_irqrestore(&m
->lock
, flags
);
645 /* PG_INIT_REQUIRED cannot be set without QUEUE_IO */
646 if (queue_io
|| test_bit(MPATHF_PG_INIT_REQUIRED
, &m
->flags
))
647 pg_init_all_paths(m
);
649 queue_work(kmultipathd
, &m
->process_queued_bios
);
650 return DM_MAPIO_SUBMITTED
;
654 if (!must_push_back_bio(m
))
656 return DM_MAPIO_REQUEUE
;
659 mpio
->pgpath
= pgpath
;
660 mpio
->nr_bytes
= nr_bytes
;
663 bio
->bi_bdev
= pgpath
->path
.dev
->bdev
;
664 bio
->bi_opf
|= REQ_FAILFAST_TRANSPORT
;
666 if (pgpath
->pg
->ps
.type
->start_io
)
667 pgpath
->pg
->ps
.type
->start_io(&pgpath
->pg
->ps
,
670 return DM_MAPIO_REMAPPED
;
673 static int multipath_map_bio(struct dm_target
*ti
, struct bio
*bio
)
675 struct multipath
*m
= ti
->private;
676 struct dm_mpath_io
*mpio
= NULL
;
678 multipath_init_per_bio_data(bio
, &mpio
, NULL
);
680 return __multipath_map_bio(m
, bio
, mpio
);
683 static void process_queued_bios_list(struct multipath
*m
)
685 if (m
->queue_mode
== DM_TYPE_BIO_BASED
)
686 queue_work(kmultipathd
, &m
->process_queued_bios
);
689 static void process_queued_bios(struct work_struct
*work
)
694 struct bio_list bios
;
695 struct blk_plug plug
;
696 struct multipath
*m
=
697 container_of(work
, struct multipath
, process_queued_bios
);
699 bio_list_init(&bios
);
701 spin_lock_irqsave(&m
->lock
, flags
);
703 if (bio_list_empty(&m
->queued_bios
)) {
704 spin_unlock_irqrestore(&m
->lock
, flags
);
708 bio_list_merge(&bios
, &m
->queued_bios
);
709 bio_list_init(&m
->queued_bios
);
711 spin_unlock_irqrestore(&m
->lock
, flags
);
713 blk_start_plug(&plug
);
714 while ((bio
= bio_list_pop(&bios
))) {
715 r
= __multipath_map_bio(m
, bio
, get_mpio_from_bio(bio
));
716 if (r
< 0 || r
== DM_MAPIO_REQUEUE
) {
719 } else if (r
== DM_MAPIO_REMAPPED
)
720 generic_make_request(bio
);
722 blk_finish_plug(&plug
);
726 * If we run out of usable paths, should we queue I/O or error it?
728 static int queue_if_no_path(struct multipath
*m
, bool queue_if_no_path
,
733 spin_lock_irqsave(&m
->lock
, flags
);
735 if (save_old_value
) {
736 if (test_bit(MPATHF_QUEUE_IF_NO_PATH
, &m
->flags
))
737 set_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH
, &m
->flags
);
739 clear_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH
, &m
->flags
);
741 if (queue_if_no_path
)
742 set_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH
, &m
->flags
);
744 clear_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH
, &m
->flags
);
746 if (queue_if_no_path
)
747 set_bit(MPATHF_QUEUE_IF_NO_PATH
, &m
->flags
);
749 clear_bit(MPATHF_QUEUE_IF_NO_PATH
, &m
->flags
);
751 spin_unlock_irqrestore(&m
->lock
, flags
);
753 if (!queue_if_no_path
) {
754 dm_table_run_md_queue_async(m
->ti
->table
);
755 process_queued_bios_list(m
);
762 * An event is triggered whenever a path is taken out of use.
763 * Includes path failure and PG bypass.
765 static void trigger_event(struct work_struct
*work
)
767 struct multipath
*m
=
768 container_of(work
, struct multipath
, trigger_event
);
770 dm_table_event(m
->ti
->table
);
773 /*-----------------------------------------------------------------
774 * Constructor/argument parsing:
775 * <#multipath feature args> [<arg>]*
776 * <#hw_handler args> [hw_handler [<arg>]*]
778 * <initial priority group>
779 * [<selector> <#selector args> [<arg>]*
780 * <#paths> <#per-path selector args>
781 * [<path> [<arg>]* ]+ ]+
782 *---------------------------------------------------------------*/
783 static int parse_path_selector(struct dm_arg_set
*as
, struct priority_group
*pg
,
784 struct dm_target
*ti
)
787 struct path_selector_type
*pst
;
790 static struct dm_arg _args
[] = {
791 {0, 1024, "invalid number of path selector args"},
794 pst
= dm_get_path_selector(dm_shift_arg(as
));
796 ti
->error
= "unknown path selector type";
800 r
= dm_read_arg_group(_args
, as
, &ps_argc
, &ti
->error
);
802 dm_put_path_selector(pst
);
806 r
= pst
->create(&pg
->ps
, ps_argc
, as
->argv
);
808 dm_put_path_selector(pst
);
809 ti
->error
= "path selector constructor failed";
814 dm_consume_args(as
, ps_argc
);
819 static struct pgpath
*parse_path(struct dm_arg_set
*as
, struct path_selector
*ps
,
820 struct dm_target
*ti
)
824 struct multipath
*m
= ti
->private;
825 struct request_queue
*q
= NULL
;
826 const char *attached_handler_name
;
828 /* we need at least a path arg */
830 ti
->error
= "no device given";
831 return ERR_PTR(-EINVAL
);
836 return ERR_PTR(-ENOMEM
);
838 r
= dm_get_device(ti
, dm_shift_arg(as
), dm_table_get_mode(ti
->table
),
841 ti
->error
= "error getting device";
845 if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER
, &m
->flags
) || m
->hw_handler_name
)
846 q
= bdev_get_queue(p
->path
.dev
->bdev
);
848 if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER
, &m
->flags
)) {
850 attached_handler_name
= scsi_dh_attached_handler_name(q
, GFP_KERNEL
);
851 if (attached_handler_name
) {
853 * Reset hw_handler_name to match the attached handler
854 * and clear any hw_handler_params associated with the
857 * NB. This modifies the table line to show the actual
858 * handler instead of the original table passed in.
860 kfree(m
->hw_handler_name
);
861 m
->hw_handler_name
= attached_handler_name
;
863 kfree(m
->hw_handler_params
);
864 m
->hw_handler_params
= NULL
;
868 if (m
->hw_handler_name
) {
869 r
= scsi_dh_attach(q
, m
->hw_handler_name
);
871 char b
[BDEVNAME_SIZE
];
873 printk(KERN_INFO
"dm-mpath: retaining handler on device %s\n",
874 bdevname(p
->path
.dev
->bdev
, b
));
878 ti
->error
= "error attaching hardware handler";
879 dm_put_device(ti
, p
->path
.dev
);
883 if (m
->hw_handler_params
) {
884 r
= scsi_dh_set_params(q
, m
->hw_handler_params
);
886 ti
->error
= "unable to set hardware "
887 "handler parameters";
888 dm_put_device(ti
, p
->path
.dev
);
894 r
= ps
->type
->add_path(ps
, &p
->path
, as
->argc
, as
->argv
, &ti
->error
);
896 dm_put_device(ti
, p
->path
.dev
);
907 static struct priority_group
*parse_priority_group(struct dm_arg_set
*as
,
910 static struct dm_arg _args
[] = {
911 {1, 1024, "invalid number of paths"},
912 {0, 1024, "invalid number of selector args"}
916 unsigned i
, nr_selector_args
, nr_args
;
917 struct priority_group
*pg
;
918 struct dm_target
*ti
= m
->ti
;
922 ti
->error
= "not enough priority group arguments";
923 return ERR_PTR(-EINVAL
);
926 pg
= alloc_priority_group();
928 ti
->error
= "couldn't allocate priority group";
929 return ERR_PTR(-ENOMEM
);
933 r
= parse_path_selector(as
, pg
, ti
);
940 r
= dm_read_arg(_args
, as
, &pg
->nr_pgpaths
, &ti
->error
);
944 r
= dm_read_arg(_args
+ 1, as
, &nr_selector_args
, &ti
->error
);
948 nr_args
= 1 + nr_selector_args
;
949 for (i
= 0; i
< pg
->nr_pgpaths
; i
++) {
950 struct pgpath
*pgpath
;
951 struct dm_arg_set path_args
;
953 if (as
->argc
< nr_args
) {
954 ti
->error
= "not enough path parameters";
959 path_args
.argc
= nr_args
;
960 path_args
.argv
= as
->argv
;
962 pgpath
= parse_path(&path_args
, &pg
->ps
, ti
);
963 if (IS_ERR(pgpath
)) {
969 list_add_tail(&pgpath
->list
, &pg
->pgpaths
);
970 dm_consume_args(as
, nr_args
);
976 free_priority_group(pg
, ti
);
980 static int parse_hw_handler(struct dm_arg_set
*as
, struct multipath
*m
)
984 struct dm_target
*ti
= m
->ti
;
986 static struct dm_arg _args
[] = {
987 {0, 1024, "invalid number of hardware handler args"},
990 if (dm_read_arg_group(_args
, as
, &hw_argc
, &ti
->error
))
996 if (m
->queue_mode
== DM_TYPE_BIO_BASED
) {
997 dm_consume_args(as
, hw_argc
);
998 DMERR("bio-based multipath doesn't allow hardware handler args");
1002 m
->hw_handler_name
= kstrdup(dm_shift_arg(as
), GFP_KERNEL
);
1008 for (i
= 0; i
<= hw_argc
- 2; i
++)
1009 len
+= strlen(as
->argv
[i
]) + 1;
1010 p
= m
->hw_handler_params
= kzalloc(len
, GFP_KERNEL
);
1012 ti
->error
= "memory allocation failed";
1016 j
= sprintf(p
, "%d", hw_argc
- 1);
1017 for (i
= 0, p
+=j
+1; i
<= hw_argc
- 2; i
++, p
+=j
+1)
1018 j
= sprintf(p
, "%s", as
->argv
[i
]);
1020 dm_consume_args(as
, hw_argc
- 1);
1024 kfree(m
->hw_handler_name
);
1025 m
->hw_handler_name
= NULL
;
1029 static int parse_features(struct dm_arg_set
*as
, struct multipath
*m
)
1033 struct dm_target
*ti
= m
->ti
;
1034 const char *arg_name
;
1036 static struct dm_arg _args
[] = {
1037 {0, 8, "invalid number of feature args"},
1038 {1, 50, "pg_init_retries must be between 1 and 50"},
1039 {0, 60000, "pg_init_delay_msecs must be between 0 and 60000"},
1042 r
= dm_read_arg_group(_args
, as
, &argc
, &ti
->error
);
1050 arg_name
= dm_shift_arg(as
);
1053 if (!strcasecmp(arg_name
, "queue_if_no_path")) {
1054 r
= queue_if_no_path(m
, true, false);
1058 if (!strcasecmp(arg_name
, "retain_attached_hw_handler")) {
1059 set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER
, &m
->flags
);
1063 if (!strcasecmp(arg_name
, "pg_init_retries") &&
1065 r
= dm_read_arg(_args
+ 1, as
, &m
->pg_init_retries
, &ti
->error
);
1070 if (!strcasecmp(arg_name
, "pg_init_delay_msecs") &&
1072 r
= dm_read_arg(_args
+ 2, as
, &m
->pg_init_delay_msecs
, &ti
->error
);
1077 if (!strcasecmp(arg_name
, "queue_mode") &&
1079 const char *queue_mode_name
= dm_shift_arg(as
);
1081 if (!strcasecmp(queue_mode_name
, "bio"))
1082 m
->queue_mode
= DM_TYPE_BIO_BASED
;
1083 else if (!strcasecmp(queue_mode_name
, "rq"))
1084 m
->queue_mode
= DM_TYPE_REQUEST_BASED
;
1085 else if (!strcasecmp(queue_mode_name
, "mq"))
1086 m
->queue_mode
= DM_TYPE_MQ_REQUEST_BASED
;
1088 ti
->error
= "Unknown 'queue_mode' requested";
1095 ti
->error
= "Unrecognised multipath feature request";
1097 } while (argc
&& !r
);
1102 static int multipath_ctr(struct dm_target
*ti
, unsigned argc
, char **argv
)
1104 /* target arguments */
1105 static struct dm_arg _args
[] = {
1106 {0, 1024, "invalid number of priority groups"},
1107 {0, 1024, "invalid initial priority group number"},
1111 struct multipath
*m
;
1112 struct dm_arg_set as
;
1113 unsigned pg_count
= 0;
1114 unsigned next_pg_num
;
1119 m
= alloc_multipath(ti
);
1121 ti
->error
= "can't allocate multipath";
1125 r
= parse_features(&as
, m
);
1129 r
= alloc_multipath_stage2(ti
, m
);
1133 r
= parse_hw_handler(&as
, m
);
1137 r
= dm_read_arg(_args
, &as
, &m
->nr_priority_groups
, &ti
->error
);
1141 r
= dm_read_arg(_args
+ 1, &as
, &next_pg_num
, &ti
->error
);
1145 if ((!m
->nr_priority_groups
&& next_pg_num
) ||
1146 (m
->nr_priority_groups
&& !next_pg_num
)) {
1147 ti
->error
= "invalid initial priority group";
1152 /* parse the priority groups */
1154 struct priority_group
*pg
;
1155 unsigned nr_valid_paths
= atomic_read(&m
->nr_valid_paths
);
1157 pg
= parse_priority_group(&as
, m
);
1163 nr_valid_paths
+= pg
->nr_pgpaths
;
1164 atomic_set(&m
->nr_valid_paths
, nr_valid_paths
);
1166 list_add_tail(&pg
->list
, &m
->priority_groups
);
1168 pg
->pg_num
= pg_count
;
1173 if (pg_count
!= m
->nr_priority_groups
) {
1174 ti
->error
= "priority group count mismatch";
1179 ti
->num_flush_bios
= 1;
1180 ti
->num_discard_bios
= 1;
1181 ti
->num_write_same_bios
= 1;
1182 if (m
->queue_mode
== DM_TYPE_BIO_BASED
)
1183 ti
->per_io_data_size
= multipath_per_bio_data_size();
1184 else if (m
->queue_mode
== DM_TYPE_MQ_REQUEST_BASED
)
1185 ti
->per_io_data_size
= sizeof(struct dm_mpath_io
);
1194 static void multipath_wait_for_pg_init_completion(struct multipath
*m
)
1196 DECLARE_WAITQUEUE(wait
, current
);
1198 add_wait_queue(&m
->pg_init_wait
, &wait
);
1201 set_current_state(TASK_UNINTERRUPTIBLE
);
1203 if (!atomic_read(&m
->pg_init_in_progress
))
1208 set_current_state(TASK_RUNNING
);
1210 remove_wait_queue(&m
->pg_init_wait
, &wait
);
1213 static void flush_multipath_work(struct multipath
*m
)
1215 set_bit(MPATHF_PG_INIT_DISABLED
, &m
->flags
);
1216 smp_mb__after_atomic();
1218 flush_workqueue(kmpath_handlerd
);
1219 multipath_wait_for_pg_init_completion(m
);
1220 flush_workqueue(kmultipathd
);
1221 flush_work(&m
->trigger_event
);
1223 clear_bit(MPATHF_PG_INIT_DISABLED
, &m
->flags
);
1224 smp_mb__after_atomic();
1227 static void multipath_dtr(struct dm_target
*ti
)
1229 struct multipath
*m
= ti
->private;
1231 flush_multipath_work(m
);
1236 * Take a path out of use.
1238 static int fail_path(struct pgpath
*pgpath
)
1240 unsigned long flags
;
1241 struct multipath
*m
= pgpath
->pg
->m
;
1243 spin_lock_irqsave(&m
->lock
, flags
);
1245 if (!pgpath
->is_active
)
1248 DMWARN("Failing path %s.", pgpath
->path
.dev
->name
);
1250 pgpath
->pg
->ps
.type
->fail_path(&pgpath
->pg
->ps
, &pgpath
->path
);
1251 pgpath
->is_active
= false;
1252 pgpath
->fail_count
++;
1254 atomic_dec(&m
->nr_valid_paths
);
1256 if (pgpath
== m
->current_pgpath
)
1257 m
->current_pgpath
= NULL
;
1259 dm_path_uevent(DM_UEVENT_PATH_FAILED
, m
->ti
,
1260 pgpath
->path
.dev
->name
, atomic_read(&m
->nr_valid_paths
));
1262 schedule_work(&m
->trigger_event
);
1265 spin_unlock_irqrestore(&m
->lock
, flags
);
1271 * Reinstate a previously-failed path
1273 static int reinstate_path(struct pgpath
*pgpath
)
1275 int r
= 0, run_queue
= 0;
1276 unsigned long flags
;
1277 struct multipath
*m
= pgpath
->pg
->m
;
1278 unsigned nr_valid_paths
;
1280 spin_lock_irqsave(&m
->lock
, flags
);
1282 if (pgpath
->is_active
)
1285 DMWARN("Reinstating path %s.", pgpath
->path
.dev
->name
);
1287 r
= pgpath
->pg
->ps
.type
->reinstate_path(&pgpath
->pg
->ps
, &pgpath
->path
);
1291 pgpath
->is_active
= true;
1293 nr_valid_paths
= atomic_inc_return(&m
->nr_valid_paths
);
1294 if (nr_valid_paths
== 1) {
1295 m
->current_pgpath
= NULL
;
1297 } else if (m
->hw_handler_name
&& (m
->current_pg
== pgpath
->pg
)) {
1298 if (queue_work(kmpath_handlerd
, &pgpath
->activate_path
.work
))
1299 atomic_inc(&m
->pg_init_in_progress
);
1302 dm_path_uevent(DM_UEVENT_PATH_REINSTATED
, m
->ti
,
1303 pgpath
->path
.dev
->name
, nr_valid_paths
);
1305 schedule_work(&m
->trigger_event
);
1308 spin_unlock_irqrestore(&m
->lock
, flags
);
1310 dm_table_run_md_queue_async(m
->ti
->table
);
1311 process_queued_bios_list(m
);
1318 * Fail or reinstate all paths that match the provided struct dm_dev.
1320 static int action_dev(struct multipath
*m
, struct dm_dev
*dev
,
1324 struct pgpath
*pgpath
;
1325 struct priority_group
*pg
;
1327 list_for_each_entry(pg
, &m
->priority_groups
, list
) {
1328 list_for_each_entry(pgpath
, &pg
->pgpaths
, list
) {
1329 if (pgpath
->path
.dev
== dev
)
1338 * Temporarily try to avoid having to use the specified PG
1340 static void bypass_pg(struct multipath
*m
, struct priority_group
*pg
,
1343 unsigned long flags
;
1345 spin_lock_irqsave(&m
->lock
, flags
);
1347 pg
->bypassed
= bypassed
;
1348 m
->current_pgpath
= NULL
;
1349 m
->current_pg
= NULL
;
1351 spin_unlock_irqrestore(&m
->lock
, flags
);
1353 schedule_work(&m
->trigger_event
);
1357 * Switch to using the specified PG from the next I/O that gets mapped
1359 static int switch_pg_num(struct multipath
*m
, const char *pgstr
)
1361 struct priority_group
*pg
;
1363 unsigned long flags
;
1366 if (!pgstr
|| (sscanf(pgstr
, "%u%c", &pgnum
, &dummy
) != 1) || !pgnum
||
1367 (pgnum
> m
->nr_priority_groups
)) {
1368 DMWARN("invalid PG number supplied to switch_pg_num");
1372 spin_lock_irqsave(&m
->lock
, flags
);
1373 list_for_each_entry(pg
, &m
->priority_groups
, list
) {
1374 pg
->bypassed
= false;
1378 m
->current_pgpath
= NULL
;
1379 m
->current_pg
= NULL
;
1382 spin_unlock_irqrestore(&m
->lock
, flags
);
1384 schedule_work(&m
->trigger_event
);
1389 * Set/clear bypassed status of a PG.
1390 * PGs are numbered upwards from 1 in the order they were declared.
1392 static int bypass_pg_num(struct multipath
*m
, const char *pgstr
, bool bypassed
)
1394 struct priority_group
*pg
;
1398 if (!pgstr
|| (sscanf(pgstr
, "%u%c", &pgnum
, &dummy
) != 1) || !pgnum
||
1399 (pgnum
> m
->nr_priority_groups
)) {
1400 DMWARN("invalid PG number supplied to bypass_pg");
1404 list_for_each_entry(pg
, &m
->priority_groups
, list
) {
1409 bypass_pg(m
, pg
, bypassed
);
1414 * Should we retry pg_init immediately?
1416 static bool pg_init_limit_reached(struct multipath
*m
, struct pgpath
*pgpath
)
1418 unsigned long flags
;
1419 bool limit_reached
= false;
1421 spin_lock_irqsave(&m
->lock
, flags
);
1423 if (atomic_read(&m
->pg_init_count
) <= m
->pg_init_retries
&&
1424 !test_bit(MPATHF_PG_INIT_DISABLED
, &m
->flags
))
1425 set_bit(MPATHF_PG_INIT_REQUIRED
, &m
->flags
);
1427 limit_reached
= true;
1429 spin_unlock_irqrestore(&m
->lock
, flags
);
1431 return limit_reached
;
1434 static void pg_init_done(void *data
, int errors
)
1436 struct pgpath
*pgpath
= data
;
1437 struct priority_group
*pg
= pgpath
->pg
;
1438 struct multipath
*m
= pg
->m
;
1439 unsigned long flags
;
1440 bool delay_retry
= false;
1442 /* device or driver problems */
1447 if (!m
->hw_handler_name
) {
1451 DMERR("Could not failover the device: Handler scsi_dh_%s "
1452 "Error %d.", m
->hw_handler_name
, errors
);
1454 * Fail path for now, so we do not ping pong
1458 case SCSI_DH_DEV_TEMP_BUSY
:
1460 * Probably doing something like FW upgrade on the
1461 * controller so try the other pg.
1463 bypass_pg(m
, pg
, true);
1466 /* Wait before retrying. */
1468 case SCSI_DH_IMM_RETRY
:
1469 case SCSI_DH_RES_TEMP_UNAVAIL
:
1470 if (pg_init_limit_reached(m
, pgpath
))
1474 case SCSI_DH_DEV_OFFLINED
:
1477 * We probably do not want to fail the path for a device
1478 * error, but this is what the old dm did. In future
1479 * patches we can do more advanced handling.
1484 spin_lock_irqsave(&m
->lock
, flags
);
1486 if (pgpath
== m
->current_pgpath
) {
1487 DMERR("Could not failover device. Error %d.", errors
);
1488 m
->current_pgpath
= NULL
;
1489 m
->current_pg
= NULL
;
1491 } else if (!test_bit(MPATHF_PG_INIT_REQUIRED
, &m
->flags
))
1492 pg
->bypassed
= false;
1494 if (atomic_dec_return(&m
->pg_init_in_progress
) > 0)
1495 /* Activations of other paths are still on going */
1498 if (test_bit(MPATHF_PG_INIT_REQUIRED
, &m
->flags
)) {
1500 set_bit(MPATHF_PG_INIT_DELAY_RETRY
, &m
->flags
);
1502 clear_bit(MPATHF_PG_INIT_DELAY_RETRY
, &m
->flags
);
1504 if (__pg_init_all_paths(m
))
1507 clear_bit(MPATHF_QUEUE_IO
, &m
->flags
);
1509 process_queued_bios_list(m
);
1512 * Wake up any thread waiting to suspend.
1514 wake_up(&m
->pg_init_wait
);
1517 spin_unlock_irqrestore(&m
->lock
, flags
);
1520 static void activate_path(struct work_struct
*work
)
1522 struct pgpath
*pgpath
=
1523 container_of(work
, struct pgpath
, activate_path
.work
);
1525 if (pgpath
->is_active
)
1526 scsi_dh_activate(bdev_get_queue(pgpath
->path
.dev
->bdev
),
1527 pg_init_done
, pgpath
);
1529 pg_init_done(pgpath
, SCSI_DH_DEV_OFFLINED
);
1532 static int noretry_error(int error
)
1543 /* Anything else could be a path failure, so should be retried */
1550 static int do_end_io(struct multipath
*m
, struct request
*clone
,
1551 int error
, struct dm_mpath_io
*mpio
)
1554 * We don't queue any clone request inside the multipath target
1555 * during end I/O handling, since those clone requests don't have
1556 * bio clones. If we queue them inside the multipath target,
1557 * we need to make bio clones, that requires memory allocation.
1558 * (See drivers/md/dm-rq.c:end_clone_bio() about why the clone requests
1559 * don't have bio clones.)
1560 * Instead of queueing the clone request here, we queue the original
1561 * request into dm core, which will remake a clone request and
1562 * clone bios for it and resubmit it later.
1564 int r
= DM_ENDIO_REQUEUE
;
1566 if (!error
&& !clone
->errors
)
1567 return 0; /* I/O complete */
1569 if (noretry_error(error
))
1573 fail_path(mpio
->pgpath
);
1575 if (!atomic_read(&m
->nr_valid_paths
)) {
1576 if (!test_bit(MPATHF_QUEUE_IF_NO_PATH
, &m
->flags
)) {
1577 if (!must_push_back_rq(m
))
1580 if (error
== -EBADE
)
1588 static int multipath_end_io(struct dm_target
*ti
, struct request
*clone
,
1589 int error
, union map_info
*map_context
)
1591 struct multipath
*m
= ti
->private;
1592 struct dm_mpath_io
*mpio
= get_mpio(map_context
);
1593 struct pgpath
*pgpath
;
1594 struct path_selector
*ps
;
1599 r
= do_end_io(m
, clone
, error
, mpio
);
1600 pgpath
= mpio
->pgpath
;
1602 ps
= &pgpath
->pg
->ps
;
1603 if (ps
->type
->end_io
)
1604 ps
->type
->end_io(ps
, &pgpath
->path
, mpio
->nr_bytes
);
1606 clear_request_fn_mpio(m
, map_context
);
1611 static int do_end_io_bio(struct multipath
*m
, struct bio
*clone
,
1612 int error
, struct dm_mpath_io
*mpio
)
1614 unsigned long flags
;
1617 return 0; /* I/O complete */
1619 if (noretry_error(error
))
1623 fail_path(mpio
->pgpath
);
1625 if (!atomic_read(&m
->nr_valid_paths
)) {
1626 if (!test_bit(MPATHF_QUEUE_IF_NO_PATH
, &m
->flags
)) {
1627 if (!must_push_back_bio(m
))
1629 return DM_ENDIO_REQUEUE
;
1631 if (error
== -EBADE
)
1636 /* Queue for the daemon to resubmit */
1637 dm_bio_restore(get_bio_details_from_bio(clone
), clone
);
1639 spin_lock_irqsave(&m
->lock
, flags
);
1640 bio_list_add(&m
->queued_bios
, clone
);
1641 spin_unlock_irqrestore(&m
->lock
, flags
);
1642 if (!test_bit(MPATHF_QUEUE_IO
, &m
->flags
))
1643 queue_work(kmultipathd
, &m
->process_queued_bios
);
1645 return DM_ENDIO_INCOMPLETE
;
1648 static int multipath_end_io_bio(struct dm_target
*ti
, struct bio
*clone
, int error
)
1650 struct multipath
*m
= ti
->private;
1651 struct dm_mpath_io
*mpio
= get_mpio_from_bio(clone
);
1652 struct pgpath
*pgpath
;
1653 struct path_selector
*ps
;
1658 r
= do_end_io_bio(m
, clone
, error
, mpio
);
1659 pgpath
= mpio
->pgpath
;
1661 ps
= &pgpath
->pg
->ps
;
1662 if (ps
->type
->end_io
)
1663 ps
->type
->end_io(ps
, &pgpath
->path
, mpio
->nr_bytes
);
1670 * Suspend can't complete until all the I/O is processed so if
1671 * the last path fails we must error any remaining I/O.
1672 * Note that if the freeze_bdev fails while suspending, the
1673 * queue_if_no_path state is lost - userspace should reset it.
1675 static void multipath_presuspend(struct dm_target
*ti
)
1677 struct multipath
*m
= ti
->private;
1679 queue_if_no_path(m
, false, true);
1682 static void multipath_postsuspend(struct dm_target
*ti
)
1684 struct multipath
*m
= ti
->private;
1686 mutex_lock(&m
->work_mutex
);
1687 flush_multipath_work(m
);
1688 mutex_unlock(&m
->work_mutex
);
1692 * Restore the queue_if_no_path setting.
1694 static void multipath_resume(struct dm_target
*ti
)
1696 struct multipath
*m
= ti
->private;
1697 unsigned long flags
;
1699 spin_lock_irqsave(&m
->lock
, flags
);
1700 if (test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH
, &m
->flags
))
1701 set_bit(MPATHF_QUEUE_IF_NO_PATH
, &m
->flags
);
1703 clear_bit(MPATHF_QUEUE_IF_NO_PATH
, &m
->flags
);
1704 spin_unlock_irqrestore(&m
->lock
, flags
);
1708 * Info output has the following format:
1709 * num_multipath_feature_args [multipath_feature_args]*
1710 * num_handler_status_args [handler_status_args]*
1711 * num_groups init_group_number
1712 * [A|D|E num_ps_status_args [ps_status_args]*
1713 * num_paths num_selector_args
1714 * [path_dev A|F fail_count [selector_args]* ]+ ]+
1716 * Table output has the following format (identical to the constructor string):
1717 * num_feature_args [features_args]*
1718 * num_handler_args hw_handler [hw_handler_args]*
1719 * num_groups init_group_number
1720 * [priority selector-name num_ps_args [ps_args]*
1721 * num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
1723 static void multipath_status(struct dm_target
*ti
, status_type_t type
,
1724 unsigned status_flags
, char *result
, unsigned maxlen
)
1727 unsigned long flags
;
1728 struct multipath
*m
= ti
->private;
1729 struct priority_group
*pg
;
1734 spin_lock_irqsave(&m
->lock
, flags
);
1737 if (type
== STATUSTYPE_INFO
)
1738 DMEMIT("2 %u %u ", test_bit(MPATHF_QUEUE_IO
, &m
->flags
),
1739 atomic_read(&m
->pg_init_count
));
1741 DMEMIT("%u ", test_bit(MPATHF_QUEUE_IF_NO_PATH
, &m
->flags
) +
1742 (m
->pg_init_retries
> 0) * 2 +
1743 (m
->pg_init_delay_msecs
!= DM_PG_INIT_DELAY_DEFAULT
) * 2 +
1744 test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER
, &m
->flags
) +
1745 (m
->queue_mode
!= DM_TYPE_REQUEST_BASED
) * 2);
1747 if (test_bit(MPATHF_QUEUE_IF_NO_PATH
, &m
->flags
))
1748 DMEMIT("queue_if_no_path ");
1749 if (m
->pg_init_retries
)
1750 DMEMIT("pg_init_retries %u ", m
->pg_init_retries
);
1751 if (m
->pg_init_delay_msecs
!= DM_PG_INIT_DELAY_DEFAULT
)
1752 DMEMIT("pg_init_delay_msecs %u ", m
->pg_init_delay_msecs
);
1753 if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER
, &m
->flags
))
1754 DMEMIT("retain_attached_hw_handler ");
1755 if (m
->queue_mode
!= DM_TYPE_REQUEST_BASED
) {
1756 switch(m
->queue_mode
) {
1757 case DM_TYPE_BIO_BASED
:
1758 DMEMIT("queue_mode bio ");
1760 case DM_TYPE_MQ_REQUEST_BASED
:
1761 DMEMIT("queue_mode mq ");
1767 if (!m
->hw_handler_name
|| type
== STATUSTYPE_INFO
)
1770 DMEMIT("1 %s ", m
->hw_handler_name
);
1772 DMEMIT("%u ", m
->nr_priority_groups
);
1775 pg_num
= m
->next_pg
->pg_num
;
1776 else if (m
->current_pg
)
1777 pg_num
= m
->current_pg
->pg_num
;
1779 pg_num
= (m
->nr_priority_groups
? 1 : 0);
1781 DMEMIT("%u ", pg_num
);
1784 case STATUSTYPE_INFO
:
1785 list_for_each_entry(pg
, &m
->priority_groups
, list
) {
1787 state
= 'D'; /* Disabled */
1788 else if (pg
== m
->current_pg
)
1789 state
= 'A'; /* Currently Active */
1791 state
= 'E'; /* Enabled */
1793 DMEMIT("%c ", state
);
1795 if (pg
->ps
.type
->status
)
1796 sz
+= pg
->ps
.type
->status(&pg
->ps
, NULL
, type
,
1802 DMEMIT("%u %u ", pg
->nr_pgpaths
,
1803 pg
->ps
.type
->info_args
);
1805 list_for_each_entry(p
, &pg
->pgpaths
, list
) {
1806 DMEMIT("%s %s %u ", p
->path
.dev
->name
,
1807 p
->is_active
? "A" : "F",
1809 if (pg
->ps
.type
->status
)
1810 sz
+= pg
->ps
.type
->status(&pg
->ps
,
1811 &p
->path
, type
, result
+ sz
,
1817 case STATUSTYPE_TABLE
:
1818 list_for_each_entry(pg
, &m
->priority_groups
, list
) {
1819 DMEMIT("%s ", pg
->ps
.type
->name
);
1821 if (pg
->ps
.type
->status
)
1822 sz
+= pg
->ps
.type
->status(&pg
->ps
, NULL
, type
,
1828 DMEMIT("%u %u ", pg
->nr_pgpaths
,
1829 pg
->ps
.type
->table_args
);
1831 list_for_each_entry(p
, &pg
->pgpaths
, list
) {
1832 DMEMIT("%s ", p
->path
.dev
->name
);
1833 if (pg
->ps
.type
->status
)
1834 sz
+= pg
->ps
.type
->status(&pg
->ps
,
1835 &p
->path
, type
, result
+ sz
,
1842 spin_unlock_irqrestore(&m
->lock
, flags
);
1845 static int multipath_message(struct dm_target
*ti
, unsigned argc
, char **argv
)
1849 struct multipath
*m
= ti
->private;
1852 mutex_lock(&m
->work_mutex
);
1854 if (dm_suspended(ti
)) {
1860 if (!strcasecmp(argv
[0], "queue_if_no_path")) {
1861 r
= queue_if_no_path(m
, true, false);
1863 } else if (!strcasecmp(argv
[0], "fail_if_no_path")) {
1864 r
= queue_if_no_path(m
, false, false);
1870 DMWARN("Invalid multipath message arguments. Expected 2 arguments, got %d.", argc
);
1874 if (!strcasecmp(argv
[0], "disable_group")) {
1875 r
= bypass_pg_num(m
, argv
[1], true);
1877 } else if (!strcasecmp(argv
[0], "enable_group")) {
1878 r
= bypass_pg_num(m
, argv
[1], false);
1880 } else if (!strcasecmp(argv
[0], "switch_group")) {
1881 r
= switch_pg_num(m
, argv
[1]);
1883 } else if (!strcasecmp(argv
[0], "reinstate_path"))
1884 action
= reinstate_path
;
1885 else if (!strcasecmp(argv
[0], "fail_path"))
1888 DMWARN("Unrecognised multipath message received: %s", argv
[0]);
1892 r
= dm_get_device(ti
, argv
[1], dm_table_get_mode(ti
->table
), &dev
);
1894 DMWARN("message: error getting device %s",
1899 r
= action_dev(m
, dev
, action
);
1901 dm_put_device(ti
, dev
);
1904 mutex_unlock(&m
->work_mutex
);
1908 static int multipath_prepare_ioctl(struct dm_target
*ti
,
1909 struct block_device
**bdev
, fmode_t
*mode
)
1911 struct multipath
*m
= ti
->private;
1912 struct pgpath
*current_pgpath
;
1915 current_pgpath
= lockless_dereference(m
->current_pgpath
);
1916 if (!current_pgpath
)
1917 current_pgpath
= choose_pgpath(m
, 0);
1919 if (current_pgpath
) {
1920 if (!test_bit(MPATHF_QUEUE_IO
, &m
->flags
)) {
1921 *bdev
= current_pgpath
->path
.dev
->bdev
;
1922 *mode
= current_pgpath
->path
.dev
->mode
;
1925 /* pg_init has not started or completed */
1929 /* No path is available */
1930 if (test_bit(MPATHF_QUEUE_IF_NO_PATH
, &m
->flags
))
1936 if (r
== -ENOTCONN
) {
1937 if (!lockless_dereference(m
->current_pg
)) {
1938 /* Path status changed, redo selection */
1939 (void) choose_pgpath(m
, 0);
1941 if (test_bit(MPATHF_PG_INIT_REQUIRED
, &m
->flags
))
1942 pg_init_all_paths(m
);
1943 dm_table_run_md_queue_async(m
->ti
->table
);
1944 process_queued_bios_list(m
);
1948 * Only pass ioctls through if the device sizes match exactly.
1950 if (!r
&& ti
->len
!= i_size_read((*bdev
)->bd_inode
) >> SECTOR_SHIFT
)
1955 static int multipath_iterate_devices(struct dm_target
*ti
,
1956 iterate_devices_callout_fn fn
, void *data
)
1958 struct multipath
*m
= ti
->private;
1959 struct priority_group
*pg
;
1963 list_for_each_entry(pg
, &m
->priority_groups
, list
) {
1964 list_for_each_entry(p
, &pg
->pgpaths
, list
) {
1965 ret
= fn(ti
, p
->path
.dev
, ti
->begin
, ti
->len
, data
);
1975 static int pgpath_busy(struct pgpath
*pgpath
)
1977 struct request_queue
*q
= bdev_get_queue(pgpath
->path
.dev
->bdev
);
1979 return blk_lld_busy(q
);
1983 * We return "busy", only when we can map I/Os but underlying devices
1984 * are busy (so even if we map I/Os now, the I/Os will wait on
1985 * the underlying queue).
1986 * In other words, if we want to kill I/Os or queue them inside us
1987 * due to map unavailability, we don't return "busy". Otherwise,
1988 * dm core won't give us the I/Os and we can't do what we want.
1990 static int multipath_busy(struct dm_target
*ti
)
1992 bool busy
= false, has_active
= false;
1993 struct multipath
*m
= ti
->private;
1994 struct priority_group
*pg
, *next_pg
;
1995 struct pgpath
*pgpath
;
1997 /* pg_init in progress or no paths available */
1998 if (atomic_read(&m
->pg_init_in_progress
) ||
1999 (!atomic_read(&m
->nr_valid_paths
) && test_bit(MPATHF_QUEUE_IF_NO_PATH
, &m
->flags
)))
2002 /* Guess which priority_group will be used at next mapping time */
2003 pg
= lockless_dereference(m
->current_pg
);
2004 next_pg
= lockless_dereference(m
->next_pg
);
2005 if (unlikely(!lockless_dereference(m
->current_pgpath
) && next_pg
))
2010 * We don't know which pg will be used at next mapping time.
2011 * We don't call choose_pgpath() here to avoid to trigger
2012 * pg_init just by busy checking.
2013 * So we don't know whether underlying devices we will be using
2014 * at next mapping time are busy or not. Just try mapping.
2020 * If there is one non-busy active path at least, the path selector
2021 * will be able to select it. So we consider such a pg as not busy.
2024 list_for_each_entry(pgpath
, &pg
->pgpaths
, list
) {
2025 if (pgpath
->is_active
) {
2027 if (!pgpath_busy(pgpath
)) {
2036 * No active path in this pg, so this pg won't be used and
2037 * the current_pg will be changed at next mapping time.
2038 * We need to try mapping to determine it.
2046 /*-----------------------------------------------------------------
2048 *---------------------------------------------------------------*/
2049 static struct target_type multipath_target
= {
2050 .name
= "multipath",
2051 .version
= {1, 12, 0},
2052 .features
= DM_TARGET_SINGLETON
| DM_TARGET_IMMUTABLE
,
2053 .module
= THIS_MODULE
,
2054 .ctr
= multipath_ctr
,
2055 .dtr
= multipath_dtr
,
2056 .map_rq
= multipath_map
,
2057 .clone_and_map_rq
= multipath_clone_and_map
,
2058 .release_clone_rq
= multipath_release_clone
,
2059 .rq_end_io
= multipath_end_io
,
2060 .map
= multipath_map_bio
,
2061 .end_io
= multipath_end_io_bio
,
2062 .presuspend
= multipath_presuspend
,
2063 .postsuspend
= multipath_postsuspend
,
2064 .resume
= multipath_resume
,
2065 .status
= multipath_status
,
2066 .message
= multipath_message
,
2067 .prepare_ioctl
= multipath_prepare_ioctl
,
2068 .iterate_devices
= multipath_iterate_devices
,
2069 .busy
= multipath_busy
,
2072 static int __init
dm_multipath_init(void)
2076 /* allocate a slab for the dm_mpath_ios */
2077 _mpio_cache
= KMEM_CACHE(dm_mpath_io
, 0);
2081 r
= dm_register_target(&multipath_target
);
2083 DMERR("request-based register failed %d", r
);
2085 goto bad_register_target
;
2088 kmultipathd
= alloc_workqueue("kmpathd", WQ_MEM_RECLAIM
, 0);
2090 DMERR("failed to create workqueue kmpathd");
2092 goto bad_alloc_kmultipathd
;
2096 * A separate workqueue is used to handle the device handlers
2097 * to avoid overloading existing workqueue. Overloading the
2098 * old workqueue would also create a bottleneck in the
2099 * path of the storage hardware device activation.
2101 kmpath_handlerd
= alloc_ordered_workqueue("kmpath_handlerd",
2103 if (!kmpath_handlerd
) {
2104 DMERR("failed to create workqueue kmpath_handlerd");
2106 goto bad_alloc_kmpath_handlerd
;
2111 bad_alloc_kmpath_handlerd
:
2112 destroy_workqueue(kmultipathd
);
2113 bad_alloc_kmultipathd
:
2114 dm_unregister_target(&multipath_target
);
2115 bad_register_target
:
2116 kmem_cache_destroy(_mpio_cache
);
2121 static void __exit
dm_multipath_exit(void)
2123 destroy_workqueue(kmpath_handlerd
);
2124 destroy_workqueue(kmultipathd
);
2126 dm_unregister_target(&multipath_target
);
2127 kmem_cache_destroy(_mpio_cache
);
2130 module_init(dm_multipath_init
);
2131 module_exit(dm_multipath_exit
);
2133 MODULE_DESCRIPTION(DM_NAME
" multipath target");
2134 MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
2135 MODULE_LICENSE("GPL");