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 */
93 enum dm_queue_mode queue_mode
;
95 struct mutex work_mutex
;
96 struct work_struct trigger_event
;
98 struct work_struct process_queued_bios
;
99 struct bio_list queued_bios
;
103 * Context information attached to each io we process.
106 struct pgpath
*pgpath
;
110 typedef int (*action_fn
) (struct pgpath
*pgpath
);
112 static struct workqueue_struct
*kmultipathd
, *kmpath_handlerd
;
113 static void trigger_event(struct work_struct
*work
);
114 static void activate_or_offline_path(struct pgpath
*pgpath
);
115 static void activate_path_work(struct work_struct
*work
);
116 static void process_queued_bios(struct work_struct
*work
);
118 /*-----------------------------------------------
119 * Multipath state flags.
120 *-----------------------------------------------*/
122 #define MPATHF_QUEUE_IO 0 /* Must we queue all I/O? */
123 #define MPATHF_QUEUE_IF_NO_PATH 1 /* Queue I/O if last path fails? */
124 #define MPATHF_SAVED_QUEUE_IF_NO_PATH 2 /* Saved state during suspension */
125 #define MPATHF_RETAIN_ATTACHED_HW_HANDLER 3 /* If there's already a hw_handler present, don't change it. */
126 #define MPATHF_PG_INIT_DISABLED 4 /* pg_init is not currently allowed */
127 #define MPATHF_PG_INIT_REQUIRED 5 /* pg_init needs calling? */
128 #define MPATHF_PG_INIT_DELAY_RETRY 6 /* Delay pg_init retry? */
130 /*-----------------------------------------------
131 * Allocation routines
132 *-----------------------------------------------*/
134 static struct pgpath
*alloc_pgpath(void)
136 struct pgpath
*pgpath
= kzalloc(sizeof(*pgpath
), GFP_KERNEL
);
139 pgpath
->is_active
= true;
140 INIT_DELAYED_WORK(&pgpath
->activate_path
, activate_path_work
);
146 static void free_pgpath(struct pgpath
*pgpath
)
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
;
167 list_for_each_entry_safe(pgpath
, tmp
, pgpaths
, list
) {
168 list_del(&pgpath
->list
);
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 spin_lock_init(&m
->lock
);
196 set_bit(MPATHF_QUEUE_IO
, &m
->flags
);
197 atomic_set(&m
->nr_valid_paths
, 0);
198 atomic_set(&m
->pg_init_in_progress
, 0);
199 atomic_set(&m
->pg_init_count
, 0);
200 m
->pg_init_delay_msecs
= DM_PG_INIT_DELAY_DEFAULT
;
201 INIT_WORK(&m
->trigger_event
, trigger_event
);
202 init_waitqueue_head(&m
->pg_init_wait
);
203 mutex_init(&m
->work_mutex
);
205 m
->queue_mode
= DM_TYPE_NONE
;
214 static int alloc_multipath_stage2(struct dm_target
*ti
, struct multipath
*m
)
216 if (m
->queue_mode
== DM_TYPE_NONE
) {
218 * Default to request-based.
220 if (dm_use_blk_mq(dm_table_get_md(ti
->table
)))
221 m
->queue_mode
= DM_TYPE_MQ_REQUEST_BASED
;
223 m
->queue_mode
= DM_TYPE_REQUEST_BASED
;
224 } else if (m
->queue_mode
== DM_TYPE_BIO_BASED
) {
225 INIT_WORK(&m
->process_queued_bios
, process_queued_bios
);
227 * bio-based doesn't support any direct scsi_dh management;
228 * it just discovers if a scsi_dh is attached.
230 set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER
, &m
->flags
);
233 dm_table_set_type(ti
->table
, m
->queue_mode
);
238 static void free_multipath(struct multipath
*m
)
240 struct priority_group
*pg
, *tmp
;
242 list_for_each_entry_safe(pg
, tmp
, &m
->priority_groups
, list
) {
244 free_priority_group(pg
, m
->ti
);
247 kfree(m
->hw_handler_name
);
248 kfree(m
->hw_handler_params
);
252 static struct dm_mpath_io
*get_mpio(union map_info
*info
)
257 static size_t multipath_per_bio_data_size(void)
259 return sizeof(struct dm_mpath_io
) + sizeof(struct dm_bio_details
);
262 static struct dm_mpath_io
*get_mpio_from_bio(struct bio
*bio
)
264 return dm_per_bio_data(bio
, multipath_per_bio_data_size());
267 static struct dm_bio_details
*get_bio_details_from_bio(struct bio
*bio
)
269 /* dm_bio_details is immediately after the dm_mpath_io in bio's per-bio-data */
270 struct dm_mpath_io
*mpio
= get_mpio_from_bio(bio
);
271 void *bio_details
= mpio
+ 1;
276 static void multipath_init_per_bio_data(struct bio
*bio
, struct dm_mpath_io
**mpio_p
,
277 struct dm_bio_details
**bio_details_p
)
279 struct dm_mpath_io
*mpio
= get_mpio_from_bio(bio
);
280 struct dm_bio_details
*bio_details
= get_bio_details_from_bio(bio
);
282 memset(mpio
, 0, sizeof(*mpio
));
283 memset(bio_details
, 0, sizeof(*bio_details
));
284 dm_bio_record(bio_details
, bio
);
289 *bio_details_p
= bio_details
;
292 /*-----------------------------------------------
294 *-----------------------------------------------*/
296 static int __pg_init_all_paths(struct multipath
*m
)
298 struct pgpath
*pgpath
;
299 unsigned long pg_init_delay
= 0;
301 lockdep_assert_held(&m
->lock
);
303 if (atomic_read(&m
->pg_init_in_progress
) || test_bit(MPATHF_PG_INIT_DISABLED
, &m
->flags
))
306 atomic_inc(&m
->pg_init_count
);
307 clear_bit(MPATHF_PG_INIT_REQUIRED
, &m
->flags
);
309 /* Check here to reset pg_init_required */
313 if (test_bit(MPATHF_PG_INIT_DELAY_RETRY
, &m
->flags
))
314 pg_init_delay
= msecs_to_jiffies(m
->pg_init_delay_msecs
!= DM_PG_INIT_DELAY_DEFAULT
?
315 m
->pg_init_delay_msecs
: DM_PG_INIT_DELAY_MSECS
);
316 list_for_each_entry(pgpath
, &m
->current_pg
->pgpaths
, list
) {
317 /* Skip failed paths */
318 if (!pgpath
->is_active
)
320 if (queue_delayed_work(kmpath_handlerd
, &pgpath
->activate_path
,
322 atomic_inc(&m
->pg_init_in_progress
);
324 return atomic_read(&m
->pg_init_in_progress
);
327 static int pg_init_all_paths(struct multipath
*m
)
332 spin_lock_irqsave(&m
->lock
, flags
);
333 ret
= __pg_init_all_paths(m
);
334 spin_unlock_irqrestore(&m
->lock
, flags
);
339 static void __switch_pg(struct multipath
*m
, struct priority_group
*pg
)
343 /* Must we initialise the PG first, and queue I/O till it's ready? */
344 if (m
->hw_handler_name
) {
345 set_bit(MPATHF_PG_INIT_REQUIRED
, &m
->flags
);
346 set_bit(MPATHF_QUEUE_IO
, &m
->flags
);
348 clear_bit(MPATHF_PG_INIT_REQUIRED
, &m
->flags
);
349 clear_bit(MPATHF_QUEUE_IO
, &m
->flags
);
352 atomic_set(&m
->pg_init_count
, 0);
355 static struct pgpath
*choose_path_in_pg(struct multipath
*m
,
356 struct priority_group
*pg
,
360 struct dm_path
*path
;
361 struct pgpath
*pgpath
;
363 path
= pg
->ps
.type
->select_path(&pg
->ps
, nr_bytes
);
365 return ERR_PTR(-ENXIO
);
367 pgpath
= path_to_pgpath(path
);
369 if (unlikely(lockless_dereference(m
->current_pg
) != pg
)) {
370 /* Only update current_pgpath if pg changed */
371 spin_lock_irqsave(&m
->lock
, flags
);
372 m
->current_pgpath
= pgpath
;
374 spin_unlock_irqrestore(&m
->lock
, flags
);
380 static struct pgpath
*choose_pgpath(struct multipath
*m
, size_t nr_bytes
)
383 struct priority_group
*pg
;
384 struct pgpath
*pgpath
;
385 unsigned bypassed
= 1;
387 if (!atomic_read(&m
->nr_valid_paths
)) {
388 clear_bit(MPATHF_QUEUE_IO
, &m
->flags
);
392 /* Were we instructed to switch PG? */
393 if (lockless_dereference(m
->next_pg
)) {
394 spin_lock_irqsave(&m
->lock
, flags
);
397 spin_unlock_irqrestore(&m
->lock
, flags
);
398 goto check_current_pg
;
401 spin_unlock_irqrestore(&m
->lock
, flags
);
402 pgpath
= choose_path_in_pg(m
, pg
, nr_bytes
);
403 if (!IS_ERR_OR_NULL(pgpath
))
407 /* Don't change PG until it has no remaining paths */
409 pg
= lockless_dereference(m
->current_pg
);
411 pgpath
= choose_path_in_pg(m
, pg
, nr_bytes
);
412 if (!IS_ERR_OR_NULL(pgpath
))
417 * Loop through priority groups until we find a valid path.
418 * First time we skip PGs marked 'bypassed'.
419 * Second time we only try the ones we skipped, but set
420 * pg_init_delay_retry so we do not hammer controllers.
423 list_for_each_entry(pg
, &m
->priority_groups
, list
) {
424 if (pg
->bypassed
== !!bypassed
)
426 pgpath
= choose_path_in_pg(m
, pg
, nr_bytes
);
427 if (!IS_ERR_OR_NULL(pgpath
)) {
429 set_bit(MPATHF_PG_INIT_DELAY_RETRY
, &m
->flags
);
433 } while (bypassed
--);
436 spin_lock_irqsave(&m
->lock
, flags
);
437 m
->current_pgpath
= NULL
;
438 m
->current_pg
= NULL
;
439 spin_unlock_irqrestore(&m
->lock
, flags
);
445 * dm_report_EIO() is a macro instead of a function to make pr_debug()
446 * report the function name and line number of the function from which
447 * it has been invoked.
449 #define dm_report_EIO(m) \
451 struct mapped_device *md = dm_table_get_md((m)->ti->table); \
453 pr_debug("%s: returning EIO; QIFNP = %d; SQIFNP = %d; DNFS = %d\n", \
454 dm_device_name(md), \
455 test_bit(MPATHF_QUEUE_IF_NO_PATH, &(m)->flags), \
456 test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &(m)->flags), \
457 dm_noflush_suspending((m)->ti)); \
461 * Map cloned requests (request-based multipath)
463 static int multipath_clone_and_map(struct dm_target
*ti
, struct request
*rq
,
464 union map_info
*map_context
,
465 struct request
**__clone
)
467 struct multipath
*m
= ti
->private;
468 size_t nr_bytes
= blk_rq_bytes(rq
);
469 struct pgpath
*pgpath
;
470 struct block_device
*bdev
;
471 struct dm_mpath_io
*mpio
= get_mpio(map_context
);
472 struct request_queue
*q
;
473 struct request
*clone
;
475 /* Do we need to select a new pgpath? */
476 pgpath
= lockless_dereference(m
->current_pgpath
);
477 if (!pgpath
|| !test_bit(MPATHF_QUEUE_IO
, &m
->flags
))
478 pgpath
= choose_pgpath(m
, nr_bytes
);
481 if (test_bit(MPATHF_QUEUE_IF_NO_PATH
, &m
->flags
))
482 return DM_MAPIO_DELAY_REQUEUE
;
483 dm_report_EIO(m
); /* Failed */
484 return DM_MAPIO_KILL
;
485 } else if (test_bit(MPATHF_QUEUE_IO
, &m
->flags
) ||
486 test_bit(MPATHF_PG_INIT_REQUIRED
, &m
->flags
)) {
487 if (pg_init_all_paths(m
))
488 return DM_MAPIO_DELAY_REQUEUE
;
489 return DM_MAPIO_REQUEUE
;
492 memset(mpio
, 0, sizeof(*mpio
));
493 mpio
->pgpath
= pgpath
;
494 mpio
->nr_bytes
= nr_bytes
;
496 bdev
= pgpath
->path
.dev
->bdev
;
497 q
= bdev_get_queue(bdev
);
498 clone
= blk_get_request(q
, rq
->cmd_flags
| REQ_NOMERGE
, GFP_ATOMIC
);
500 /* EBUSY, ENODEV or EWOULDBLOCK: requeue */
501 bool queue_dying
= blk_queue_dying(q
);
502 DMERR_LIMIT("blk_get_request() returned %ld%s - requeuing",
503 PTR_ERR(clone
), queue_dying
? " (path offline)" : "");
505 atomic_inc(&m
->pg_init_in_progress
);
506 activate_or_offline_path(pgpath
);
507 return DM_MAPIO_REQUEUE
;
509 return DM_MAPIO_DELAY_REQUEUE
;
511 clone
->bio
= clone
->biotail
= NULL
;
512 clone
->rq_disk
= bdev
->bd_disk
;
513 clone
->cmd_flags
|= REQ_FAILFAST_TRANSPORT
;
516 if (pgpath
->pg
->ps
.type
->start_io
)
517 pgpath
->pg
->ps
.type
->start_io(&pgpath
->pg
->ps
,
520 return DM_MAPIO_REMAPPED
;
523 static void multipath_release_clone(struct request
*clone
)
525 blk_put_request(clone
);
529 * Map cloned bios (bio-based multipath)
531 static int __multipath_map_bio(struct multipath
*m
, struct bio
*bio
, struct dm_mpath_io
*mpio
)
533 size_t nr_bytes
= bio
->bi_iter
.bi_size
;
534 struct pgpath
*pgpath
;
538 /* Do we need to select a new pgpath? */
539 pgpath
= lockless_dereference(m
->current_pgpath
);
540 queue_io
= test_bit(MPATHF_QUEUE_IO
, &m
->flags
);
541 if (!pgpath
|| !queue_io
)
542 pgpath
= choose_pgpath(m
, nr_bytes
);
544 if ((pgpath
&& queue_io
) ||
545 (!pgpath
&& test_bit(MPATHF_QUEUE_IF_NO_PATH
, &m
->flags
))) {
546 /* Queue for the daemon to resubmit */
547 spin_lock_irqsave(&m
->lock
, flags
);
548 bio_list_add(&m
->queued_bios
, bio
);
549 spin_unlock_irqrestore(&m
->lock
, flags
);
550 /* PG_INIT_REQUIRED cannot be set without QUEUE_IO */
551 if (queue_io
|| test_bit(MPATHF_PG_INIT_REQUIRED
, &m
->flags
))
552 pg_init_all_paths(m
);
554 queue_work(kmultipathd
, &m
->process_queued_bios
);
555 return DM_MAPIO_SUBMITTED
;
559 if (test_bit(MPATHF_QUEUE_IF_NO_PATH
, &m
->flags
))
560 return DM_MAPIO_REQUEUE
;
565 mpio
->pgpath
= pgpath
;
566 mpio
->nr_bytes
= nr_bytes
;
569 bio
->bi_bdev
= pgpath
->path
.dev
->bdev
;
570 bio
->bi_opf
|= REQ_FAILFAST_TRANSPORT
;
572 if (pgpath
->pg
->ps
.type
->start_io
)
573 pgpath
->pg
->ps
.type
->start_io(&pgpath
->pg
->ps
,
576 return DM_MAPIO_REMAPPED
;
579 static int multipath_map_bio(struct dm_target
*ti
, struct bio
*bio
)
581 struct multipath
*m
= ti
->private;
582 struct dm_mpath_io
*mpio
= NULL
;
584 multipath_init_per_bio_data(bio
, &mpio
, NULL
);
586 return __multipath_map_bio(m
, bio
, mpio
);
589 static void process_queued_io_list(struct multipath
*m
)
591 if (m
->queue_mode
== DM_TYPE_MQ_REQUEST_BASED
)
592 dm_mq_kick_requeue_list(dm_table_get_md(m
->ti
->table
));
593 else if (m
->queue_mode
== DM_TYPE_BIO_BASED
)
594 queue_work(kmultipathd
, &m
->process_queued_bios
);
597 static void process_queued_bios(struct work_struct
*work
)
602 struct bio_list bios
;
603 struct blk_plug plug
;
604 struct multipath
*m
=
605 container_of(work
, struct multipath
, process_queued_bios
);
607 bio_list_init(&bios
);
609 spin_lock_irqsave(&m
->lock
, flags
);
611 if (bio_list_empty(&m
->queued_bios
)) {
612 spin_unlock_irqrestore(&m
->lock
, flags
);
616 bio_list_merge(&bios
, &m
->queued_bios
);
617 bio_list_init(&m
->queued_bios
);
619 spin_unlock_irqrestore(&m
->lock
, flags
);
621 blk_start_plug(&plug
);
622 while ((bio
= bio_list_pop(&bios
))) {
623 r
= __multipath_map_bio(m
, bio
, get_mpio_from_bio(bio
));
624 if (r
< 0 || r
== DM_MAPIO_REQUEUE
) {
627 } else if (r
== DM_MAPIO_REMAPPED
)
628 generic_make_request(bio
);
630 blk_finish_plug(&plug
);
633 static void assign_bit(bool value
, long nr
, unsigned long *addr
)
642 * If we run out of usable paths, should we queue I/O or error it?
644 static int queue_if_no_path(struct multipath
*m
, bool queue_if_no_path
,
649 spin_lock_irqsave(&m
->lock
, flags
);
650 assign_bit((save_old_value
&& test_bit(MPATHF_QUEUE_IF_NO_PATH
, &m
->flags
)) ||
651 (!save_old_value
&& queue_if_no_path
),
652 MPATHF_SAVED_QUEUE_IF_NO_PATH
, &m
->flags
);
653 assign_bit(queue_if_no_path
|| dm_noflush_suspending(m
->ti
),
654 MPATHF_QUEUE_IF_NO_PATH
, &m
->flags
);
655 spin_unlock_irqrestore(&m
->lock
, flags
);
657 if (!queue_if_no_path
) {
658 dm_table_run_md_queue_async(m
->ti
->table
);
659 process_queued_io_list(m
);
666 * An event is triggered whenever a path is taken out of use.
667 * Includes path failure and PG bypass.
669 static void trigger_event(struct work_struct
*work
)
671 struct multipath
*m
=
672 container_of(work
, struct multipath
, trigger_event
);
674 dm_table_event(m
->ti
->table
);
677 /*-----------------------------------------------------------------
678 * Constructor/argument parsing:
679 * <#multipath feature args> [<arg>]*
680 * <#hw_handler args> [hw_handler [<arg>]*]
682 * <initial priority group>
683 * [<selector> <#selector args> [<arg>]*
684 * <#paths> <#per-path selector args>
685 * [<path> [<arg>]* ]+ ]+
686 *---------------------------------------------------------------*/
687 static int parse_path_selector(struct dm_arg_set
*as
, struct priority_group
*pg
,
688 struct dm_target
*ti
)
691 struct path_selector_type
*pst
;
694 static struct dm_arg _args
[] = {
695 {0, 1024, "invalid number of path selector args"},
698 pst
= dm_get_path_selector(dm_shift_arg(as
));
700 ti
->error
= "unknown path selector type";
704 r
= dm_read_arg_group(_args
, as
, &ps_argc
, &ti
->error
);
706 dm_put_path_selector(pst
);
710 r
= pst
->create(&pg
->ps
, ps_argc
, as
->argv
);
712 dm_put_path_selector(pst
);
713 ti
->error
= "path selector constructor failed";
718 dm_consume_args(as
, ps_argc
);
723 static struct pgpath
*parse_path(struct dm_arg_set
*as
, struct path_selector
*ps
,
724 struct dm_target
*ti
)
728 struct multipath
*m
= ti
->private;
729 struct request_queue
*q
= NULL
;
730 const char *attached_handler_name
;
732 /* we need at least a path arg */
734 ti
->error
= "no device given";
735 return ERR_PTR(-EINVAL
);
740 return ERR_PTR(-ENOMEM
);
742 r
= dm_get_device(ti
, dm_shift_arg(as
), dm_table_get_mode(ti
->table
),
745 ti
->error
= "error getting device";
749 if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER
, &m
->flags
) || m
->hw_handler_name
)
750 q
= bdev_get_queue(p
->path
.dev
->bdev
);
752 if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER
, &m
->flags
)) {
754 attached_handler_name
= scsi_dh_attached_handler_name(q
, GFP_KERNEL
);
755 if (attached_handler_name
) {
757 * Clear any hw_handler_params associated with a
758 * handler that isn't already attached.
760 if (m
->hw_handler_name
&& strcmp(attached_handler_name
, m
->hw_handler_name
)) {
761 kfree(m
->hw_handler_params
);
762 m
->hw_handler_params
= NULL
;
766 * Reset hw_handler_name to match the attached handler
768 * NB. This modifies the table line to show the actual
769 * handler instead of the original table passed in.
771 kfree(m
->hw_handler_name
);
772 m
->hw_handler_name
= attached_handler_name
;
776 if (m
->hw_handler_name
) {
777 r
= scsi_dh_attach(q
, m
->hw_handler_name
);
779 char b
[BDEVNAME_SIZE
];
781 printk(KERN_INFO
"dm-mpath: retaining handler on device %s\n",
782 bdevname(p
->path
.dev
->bdev
, b
));
786 ti
->error
= "error attaching hardware handler";
787 dm_put_device(ti
, p
->path
.dev
);
791 if (m
->hw_handler_params
) {
792 r
= scsi_dh_set_params(q
, m
->hw_handler_params
);
794 ti
->error
= "unable to set hardware "
795 "handler parameters";
796 dm_put_device(ti
, p
->path
.dev
);
802 r
= ps
->type
->add_path(ps
, &p
->path
, as
->argc
, as
->argv
, &ti
->error
);
804 dm_put_device(ti
, p
->path
.dev
);
815 static struct priority_group
*parse_priority_group(struct dm_arg_set
*as
,
818 static struct dm_arg _args
[] = {
819 {1, 1024, "invalid number of paths"},
820 {0, 1024, "invalid number of selector args"}
824 unsigned i
, nr_selector_args
, nr_args
;
825 struct priority_group
*pg
;
826 struct dm_target
*ti
= m
->ti
;
830 ti
->error
= "not enough priority group arguments";
831 return ERR_PTR(-EINVAL
);
834 pg
= alloc_priority_group();
836 ti
->error
= "couldn't allocate priority group";
837 return ERR_PTR(-ENOMEM
);
841 r
= parse_path_selector(as
, pg
, ti
);
848 r
= dm_read_arg(_args
, as
, &pg
->nr_pgpaths
, &ti
->error
);
852 r
= dm_read_arg(_args
+ 1, as
, &nr_selector_args
, &ti
->error
);
856 nr_args
= 1 + nr_selector_args
;
857 for (i
= 0; i
< pg
->nr_pgpaths
; i
++) {
858 struct pgpath
*pgpath
;
859 struct dm_arg_set path_args
;
861 if (as
->argc
< nr_args
) {
862 ti
->error
= "not enough path parameters";
867 path_args
.argc
= nr_args
;
868 path_args
.argv
= as
->argv
;
870 pgpath
= parse_path(&path_args
, &pg
->ps
, ti
);
871 if (IS_ERR(pgpath
)) {
877 list_add_tail(&pgpath
->list
, &pg
->pgpaths
);
878 dm_consume_args(as
, nr_args
);
884 free_priority_group(pg
, ti
);
888 static int parse_hw_handler(struct dm_arg_set
*as
, struct multipath
*m
)
892 struct dm_target
*ti
= m
->ti
;
894 static struct dm_arg _args
[] = {
895 {0, 1024, "invalid number of hardware handler args"},
898 if (dm_read_arg_group(_args
, as
, &hw_argc
, &ti
->error
))
904 if (m
->queue_mode
== DM_TYPE_BIO_BASED
) {
905 dm_consume_args(as
, hw_argc
);
906 DMERR("bio-based multipath doesn't allow hardware handler args");
910 m
->hw_handler_name
= kstrdup(dm_shift_arg(as
), GFP_KERNEL
);
911 if (!m
->hw_handler_name
)
918 for (i
= 0; i
<= hw_argc
- 2; i
++)
919 len
+= strlen(as
->argv
[i
]) + 1;
920 p
= m
->hw_handler_params
= kzalloc(len
, GFP_KERNEL
);
922 ti
->error
= "memory allocation failed";
926 j
= sprintf(p
, "%d", hw_argc
- 1);
927 for (i
= 0, p
+=j
+1; i
<= hw_argc
- 2; i
++, p
+=j
+1)
928 j
= sprintf(p
, "%s", as
->argv
[i
]);
930 dm_consume_args(as
, hw_argc
- 1);
934 kfree(m
->hw_handler_name
);
935 m
->hw_handler_name
= NULL
;
939 static int parse_features(struct dm_arg_set
*as
, struct multipath
*m
)
943 struct dm_target
*ti
= m
->ti
;
944 const char *arg_name
;
946 static struct dm_arg _args
[] = {
947 {0, 8, "invalid number of feature args"},
948 {1, 50, "pg_init_retries must be between 1 and 50"},
949 {0, 60000, "pg_init_delay_msecs must be between 0 and 60000"},
952 r
= dm_read_arg_group(_args
, as
, &argc
, &ti
->error
);
960 arg_name
= dm_shift_arg(as
);
963 if (!strcasecmp(arg_name
, "queue_if_no_path")) {
964 r
= queue_if_no_path(m
, true, false);
968 if (!strcasecmp(arg_name
, "retain_attached_hw_handler")) {
969 set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER
, &m
->flags
);
973 if (!strcasecmp(arg_name
, "pg_init_retries") &&
975 r
= dm_read_arg(_args
+ 1, as
, &m
->pg_init_retries
, &ti
->error
);
980 if (!strcasecmp(arg_name
, "pg_init_delay_msecs") &&
982 r
= dm_read_arg(_args
+ 2, as
, &m
->pg_init_delay_msecs
, &ti
->error
);
987 if (!strcasecmp(arg_name
, "queue_mode") &&
989 const char *queue_mode_name
= dm_shift_arg(as
);
991 if (!strcasecmp(queue_mode_name
, "bio"))
992 m
->queue_mode
= DM_TYPE_BIO_BASED
;
993 else if (!strcasecmp(queue_mode_name
, "rq"))
994 m
->queue_mode
= DM_TYPE_REQUEST_BASED
;
995 else if (!strcasecmp(queue_mode_name
, "mq"))
996 m
->queue_mode
= DM_TYPE_MQ_REQUEST_BASED
;
998 ti
->error
= "Unknown 'queue_mode' requested";
1005 ti
->error
= "Unrecognised multipath feature request";
1007 } while (argc
&& !r
);
1012 static int multipath_ctr(struct dm_target
*ti
, unsigned argc
, char **argv
)
1014 /* target arguments */
1015 static struct dm_arg _args
[] = {
1016 {0, 1024, "invalid number of priority groups"},
1017 {0, 1024, "invalid initial priority group number"},
1021 struct multipath
*m
;
1022 struct dm_arg_set as
;
1023 unsigned pg_count
= 0;
1024 unsigned next_pg_num
;
1029 m
= alloc_multipath(ti
);
1031 ti
->error
= "can't allocate multipath";
1035 r
= parse_features(&as
, m
);
1039 r
= alloc_multipath_stage2(ti
, m
);
1043 r
= parse_hw_handler(&as
, m
);
1047 r
= dm_read_arg(_args
, &as
, &m
->nr_priority_groups
, &ti
->error
);
1051 r
= dm_read_arg(_args
+ 1, &as
, &next_pg_num
, &ti
->error
);
1055 if ((!m
->nr_priority_groups
&& next_pg_num
) ||
1056 (m
->nr_priority_groups
&& !next_pg_num
)) {
1057 ti
->error
= "invalid initial priority group";
1062 /* parse the priority groups */
1064 struct priority_group
*pg
;
1065 unsigned nr_valid_paths
= atomic_read(&m
->nr_valid_paths
);
1067 pg
= parse_priority_group(&as
, m
);
1073 nr_valid_paths
+= pg
->nr_pgpaths
;
1074 atomic_set(&m
->nr_valid_paths
, nr_valid_paths
);
1076 list_add_tail(&pg
->list
, &m
->priority_groups
);
1078 pg
->pg_num
= pg_count
;
1083 if (pg_count
!= m
->nr_priority_groups
) {
1084 ti
->error
= "priority group count mismatch";
1089 ti
->num_flush_bios
= 1;
1090 ti
->num_discard_bios
= 1;
1091 ti
->num_write_same_bios
= 1;
1092 ti
->num_write_zeroes_bios
= 1;
1093 if (m
->queue_mode
== DM_TYPE_BIO_BASED
)
1094 ti
->per_io_data_size
= multipath_per_bio_data_size();
1096 ti
->per_io_data_size
= sizeof(struct dm_mpath_io
);
1105 static void multipath_wait_for_pg_init_completion(struct multipath
*m
)
1110 prepare_to_wait(&m
->pg_init_wait
, &wait
, TASK_UNINTERRUPTIBLE
);
1112 if (!atomic_read(&m
->pg_init_in_progress
))
1117 finish_wait(&m
->pg_init_wait
, &wait
);
1120 static void flush_multipath_work(struct multipath
*m
)
1122 set_bit(MPATHF_PG_INIT_DISABLED
, &m
->flags
);
1123 smp_mb__after_atomic();
1125 flush_workqueue(kmpath_handlerd
);
1126 multipath_wait_for_pg_init_completion(m
);
1127 flush_workqueue(kmultipathd
);
1128 flush_work(&m
->trigger_event
);
1130 clear_bit(MPATHF_PG_INIT_DISABLED
, &m
->flags
);
1131 smp_mb__after_atomic();
1134 static void multipath_dtr(struct dm_target
*ti
)
1136 struct multipath
*m
= ti
->private;
1138 flush_multipath_work(m
);
1143 * Take a path out of use.
1145 static int fail_path(struct pgpath
*pgpath
)
1147 unsigned long flags
;
1148 struct multipath
*m
= pgpath
->pg
->m
;
1150 spin_lock_irqsave(&m
->lock
, flags
);
1152 if (!pgpath
->is_active
)
1155 DMWARN("Failing path %s.", pgpath
->path
.dev
->name
);
1157 pgpath
->pg
->ps
.type
->fail_path(&pgpath
->pg
->ps
, &pgpath
->path
);
1158 pgpath
->is_active
= false;
1159 pgpath
->fail_count
++;
1161 atomic_dec(&m
->nr_valid_paths
);
1163 if (pgpath
== m
->current_pgpath
)
1164 m
->current_pgpath
= NULL
;
1166 dm_path_uevent(DM_UEVENT_PATH_FAILED
, m
->ti
,
1167 pgpath
->path
.dev
->name
, atomic_read(&m
->nr_valid_paths
));
1169 schedule_work(&m
->trigger_event
);
1172 spin_unlock_irqrestore(&m
->lock
, flags
);
1178 * Reinstate a previously-failed path
1180 static int reinstate_path(struct pgpath
*pgpath
)
1182 int r
= 0, run_queue
= 0;
1183 unsigned long flags
;
1184 struct multipath
*m
= pgpath
->pg
->m
;
1185 unsigned nr_valid_paths
;
1187 spin_lock_irqsave(&m
->lock
, flags
);
1189 if (pgpath
->is_active
)
1192 DMWARN("Reinstating path %s.", pgpath
->path
.dev
->name
);
1194 r
= pgpath
->pg
->ps
.type
->reinstate_path(&pgpath
->pg
->ps
, &pgpath
->path
);
1198 pgpath
->is_active
= true;
1200 nr_valid_paths
= atomic_inc_return(&m
->nr_valid_paths
);
1201 if (nr_valid_paths
== 1) {
1202 m
->current_pgpath
= NULL
;
1204 } else if (m
->hw_handler_name
&& (m
->current_pg
== pgpath
->pg
)) {
1205 if (queue_work(kmpath_handlerd
, &pgpath
->activate_path
.work
))
1206 atomic_inc(&m
->pg_init_in_progress
);
1209 dm_path_uevent(DM_UEVENT_PATH_REINSTATED
, m
->ti
,
1210 pgpath
->path
.dev
->name
, nr_valid_paths
);
1212 schedule_work(&m
->trigger_event
);
1215 spin_unlock_irqrestore(&m
->lock
, flags
);
1217 dm_table_run_md_queue_async(m
->ti
->table
);
1218 process_queued_io_list(m
);
1225 * Fail or reinstate all paths that match the provided struct dm_dev.
1227 static int action_dev(struct multipath
*m
, struct dm_dev
*dev
,
1231 struct pgpath
*pgpath
;
1232 struct priority_group
*pg
;
1234 list_for_each_entry(pg
, &m
->priority_groups
, list
) {
1235 list_for_each_entry(pgpath
, &pg
->pgpaths
, list
) {
1236 if (pgpath
->path
.dev
== dev
)
1245 * Temporarily try to avoid having to use the specified PG
1247 static void bypass_pg(struct multipath
*m
, struct priority_group
*pg
,
1250 unsigned long flags
;
1252 spin_lock_irqsave(&m
->lock
, flags
);
1254 pg
->bypassed
= bypassed
;
1255 m
->current_pgpath
= NULL
;
1256 m
->current_pg
= NULL
;
1258 spin_unlock_irqrestore(&m
->lock
, flags
);
1260 schedule_work(&m
->trigger_event
);
1264 * Switch to using the specified PG from the next I/O that gets mapped
1266 static int switch_pg_num(struct multipath
*m
, const char *pgstr
)
1268 struct priority_group
*pg
;
1270 unsigned long flags
;
1273 if (!pgstr
|| (sscanf(pgstr
, "%u%c", &pgnum
, &dummy
) != 1) || !pgnum
||
1274 !m
->nr_priority_groups
|| (pgnum
> m
->nr_priority_groups
)) {
1275 DMWARN("invalid PG number supplied to switch_pg_num");
1279 spin_lock_irqsave(&m
->lock
, flags
);
1280 list_for_each_entry(pg
, &m
->priority_groups
, list
) {
1281 pg
->bypassed
= false;
1285 m
->current_pgpath
= NULL
;
1286 m
->current_pg
= NULL
;
1289 spin_unlock_irqrestore(&m
->lock
, flags
);
1291 schedule_work(&m
->trigger_event
);
1296 * Set/clear bypassed status of a PG.
1297 * PGs are numbered upwards from 1 in the order they were declared.
1299 static int bypass_pg_num(struct multipath
*m
, const char *pgstr
, bool bypassed
)
1301 struct priority_group
*pg
;
1305 if (!pgstr
|| (sscanf(pgstr
, "%u%c", &pgnum
, &dummy
) != 1) || !pgnum
||
1306 !m
->nr_priority_groups
|| (pgnum
> m
->nr_priority_groups
)) {
1307 DMWARN("invalid PG number supplied to bypass_pg");
1311 list_for_each_entry(pg
, &m
->priority_groups
, list
) {
1316 bypass_pg(m
, pg
, bypassed
);
1321 * Should we retry pg_init immediately?
1323 static bool pg_init_limit_reached(struct multipath
*m
, struct pgpath
*pgpath
)
1325 unsigned long flags
;
1326 bool limit_reached
= false;
1328 spin_lock_irqsave(&m
->lock
, flags
);
1330 if (atomic_read(&m
->pg_init_count
) <= m
->pg_init_retries
&&
1331 !test_bit(MPATHF_PG_INIT_DISABLED
, &m
->flags
))
1332 set_bit(MPATHF_PG_INIT_REQUIRED
, &m
->flags
);
1334 limit_reached
= true;
1336 spin_unlock_irqrestore(&m
->lock
, flags
);
1338 return limit_reached
;
1341 static void pg_init_done(void *data
, int errors
)
1343 struct pgpath
*pgpath
= data
;
1344 struct priority_group
*pg
= pgpath
->pg
;
1345 struct multipath
*m
= pg
->m
;
1346 unsigned long flags
;
1347 bool delay_retry
= false;
1349 /* device or driver problems */
1354 if (!m
->hw_handler_name
) {
1358 DMERR("Could not failover the device: Handler scsi_dh_%s "
1359 "Error %d.", m
->hw_handler_name
, errors
);
1361 * Fail path for now, so we do not ping pong
1365 case SCSI_DH_DEV_TEMP_BUSY
:
1367 * Probably doing something like FW upgrade on the
1368 * controller so try the other pg.
1370 bypass_pg(m
, pg
, true);
1373 /* Wait before retrying. */
1375 case SCSI_DH_IMM_RETRY
:
1376 case SCSI_DH_RES_TEMP_UNAVAIL
:
1377 if (pg_init_limit_reached(m
, pgpath
))
1381 case SCSI_DH_DEV_OFFLINED
:
1384 * We probably do not want to fail the path for a device
1385 * error, but this is what the old dm did. In future
1386 * patches we can do more advanced handling.
1391 spin_lock_irqsave(&m
->lock
, flags
);
1393 if (pgpath
== m
->current_pgpath
) {
1394 DMERR("Could not failover device. Error %d.", errors
);
1395 m
->current_pgpath
= NULL
;
1396 m
->current_pg
= NULL
;
1398 } else if (!test_bit(MPATHF_PG_INIT_REQUIRED
, &m
->flags
))
1399 pg
->bypassed
= false;
1401 if (atomic_dec_return(&m
->pg_init_in_progress
) > 0)
1402 /* Activations of other paths are still on going */
1405 if (test_bit(MPATHF_PG_INIT_REQUIRED
, &m
->flags
)) {
1407 set_bit(MPATHF_PG_INIT_DELAY_RETRY
, &m
->flags
);
1409 clear_bit(MPATHF_PG_INIT_DELAY_RETRY
, &m
->flags
);
1411 if (__pg_init_all_paths(m
))
1414 clear_bit(MPATHF_QUEUE_IO
, &m
->flags
);
1416 process_queued_io_list(m
);
1419 * Wake up any thread waiting to suspend.
1421 wake_up(&m
->pg_init_wait
);
1424 spin_unlock_irqrestore(&m
->lock
, flags
);
1427 static void activate_or_offline_path(struct pgpath
*pgpath
)
1429 struct request_queue
*q
= bdev_get_queue(pgpath
->path
.dev
->bdev
);
1431 if (pgpath
->is_active
&& !blk_queue_dying(q
))
1432 scsi_dh_activate(q
, pg_init_done
, pgpath
);
1434 pg_init_done(pgpath
, SCSI_DH_DEV_OFFLINED
);
1437 static void activate_path_work(struct work_struct
*work
)
1439 struct pgpath
*pgpath
=
1440 container_of(work
, struct pgpath
, activate_path
.work
);
1442 activate_or_offline_path(pgpath
);
1445 static int noretry_error(int error
)
1450 * EBADE signals an reservation conflict.
1451 * We shouldn't fail the path here as we can communicate with
1452 * the target. We should failover to the next path, but in
1453 * doing so we might be causing a ping-pong between paths.
1454 * So just return the reservation conflict error.
1464 /* Anything else could be a path failure, so should be retried */
1468 static int multipath_end_io(struct dm_target
*ti
, struct request
*clone
,
1469 int error
, union map_info
*map_context
)
1471 struct dm_mpath_io
*mpio
= get_mpio(map_context
);
1472 struct pgpath
*pgpath
= mpio
->pgpath
;
1473 int r
= DM_ENDIO_DONE
;
1476 * We don't queue any clone request inside the multipath target
1477 * during end I/O handling, since those clone requests don't have
1478 * bio clones. If we queue them inside the multipath target,
1479 * we need to make bio clones, that requires memory allocation.
1480 * (See drivers/md/dm-rq.c:end_clone_bio() about why the clone requests
1481 * don't have bio clones.)
1482 * Instead of queueing the clone request here, we queue the original
1483 * request into dm core, which will remake a clone request and
1484 * clone bios for it and resubmit it later.
1486 if (error
&& !noretry_error(error
)) {
1487 struct multipath
*m
= ti
->private;
1489 r
= DM_ENDIO_REQUEUE
;
1494 if (atomic_read(&m
->nr_valid_paths
) == 0 &&
1495 !test_bit(MPATHF_QUEUE_IF_NO_PATH
, &m
->flags
)) {
1498 /* complete with the original error */
1504 struct path_selector
*ps
= &pgpath
->pg
->ps
;
1506 if (ps
->type
->end_io
)
1507 ps
->type
->end_io(ps
, &pgpath
->path
, mpio
->nr_bytes
);
1513 static int do_end_io_bio(struct multipath
*m
, struct bio
*clone
,
1514 int error
, struct dm_mpath_io
*mpio
)
1516 unsigned long flags
;
1519 return 0; /* I/O complete */
1521 if (noretry_error(error
))
1525 fail_path(mpio
->pgpath
);
1527 if (atomic_read(&m
->nr_valid_paths
) == 0 &&
1528 !test_bit(MPATHF_QUEUE_IF_NO_PATH
, &m
->flags
)) {
1533 /* Queue for the daemon to resubmit */
1534 dm_bio_restore(get_bio_details_from_bio(clone
), clone
);
1536 spin_lock_irqsave(&m
->lock
, flags
);
1537 bio_list_add(&m
->queued_bios
, clone
);
1538 spin_unlock_irqrestore(&m
->lock
, flags
);
1539 if (!test_bit(MPATHF_QUEUE_IO
, &m
->flags
))
1540 queue_work(kmultipathd
, &m
->process_queued_bios
);
1542 return DM_ENDIO_INCOMPLETE
;
1545 static int multipath_end_io_bio(struct dm_target
*ti
, struct bio
*clone
, int error
)
1547 struct multipath
*m
= ti
->private;
1548 struct dm_mpath_io
*mpio
= get_mpio_from_bio(clone
);
1549 struct pgpath
*pgpath
;
1550 struct path_selector
*ps
;
1555 r
= do_end_io_bio(m
, clone
, error
, mpio
);
1556 pgpath
= mpio
->pgpath
;
1558 ps
= &pgpath
->pg
->ps
;
1559 if (ps
->type
->end_io
)
1560 ps
->type
->end_io(ps
, &pgpath
->path
, mpio
->nr_bytes
);
1567 * Suspend can't complete until all the I/O is processed so if
1568 * the last path fails we must error any remaining I/O.
1569 * Note that if the freeze_bdev fails while suspending, the
1570 * queue_if_no_path state is lost - userspace should reset it.
1572 static void multipath_presuspend(struct dm_target
*ti
)
1574 struct multipath
*m
= ti
->private;
1576 queue_if_no_path(m
, false, true);
1579 static void multipath_postsuspend(struct dm_target
*ti
)
1581 struct multipath
*m
= ti
->private;
1583 mutex_lock(&m
->work_mutex
);
1584 flush_multipath_work(m
);
1585 mutex_unlock(&m
->work_mutex
);
1589 * Restore the queue_if_no_path setting.
1591 static void multipath_resume(struct dm_target
*ti
)
1593 struct multipath
*m
= ti
->private;
1594 unsigned long flags
;
1596 spin_lock_irqsave(&m
->lock
, flags
);
1597 assign_bit(test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH
, &m
->flags
),
1598 MPATHF_QUEUE_IF_NO_PATH
, &m
->flags
);
1599 spin_unlock_irqrestore(&m
->lock
, flags
);
1603 * Info output has the following format:
1604 * num_multipath_feature_args [multipath_feature_args]*
1605 * num_handler_status_args [handler_status_args]*
1606 * num_groups init_group_number
1607 * [A|D|E num_ps_status_args [ps_status_args]*
1608 * num_paths num_selector_args
1609 * [path_dev A|F fail_count [selector_args]* ]+ ]+
1611 * Table output has the following format (identical to the constructor string):
1612 * num_feature_args [features_args]*
1613 * num_handler_args hw_handler [hw_handler_args]*
1614 * num_groups init_group_number
1615 * [priority selector-name num_ps_args [ps_args]*
1616 * num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
1618 static void multipath_status(struct dm_target
*ti
, status_type_t type
,
1619 unsigned status_flags
, char *result
, unsigned maxlen
)
1622 unsigned long flags
;
1623 struct multipath
*m
= ti
->private;
1624 struct priority_group
*pg
;
1629 spin_lock_irqsave(&m
->lock
, flags
);
1632 if (type
== STATUSTYPE_INFO
)
1633 DMEMIT("2 %u %u ", test_bit(MPATHF_QUEUE_IO
, &m
->flags
),
1634 atomic_read(&m
->pg_init_count
));
1636 DMEMIT("%u ", test_bit(MPATHF_QUEUE_IF_NO_PATH
, &m
->flags
) +
1637 (m
->pg_init_retries
> 0) * 2 +
1638 (m
->pg_init_delay_msecs
!= DM_PG_INIT_DELAY_DEFAULT
) * 2 +
1639 test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER
, &m
->flags
) +
1640 (m
->queue_mode
!= DM_TYPE_REQUEST_BASED
) * 2);
1642 if (test_bit(MPATHF_QUEUE_IF_NO_PATH
, &m
->flags
))
1643 DMEMIT("queue_if_no_path ");
1644 if (m
->pg_init_retries
)
1645 DMEMIT("pg_init_retries %u ", m
->pg_init_retries
);
1646 if (m
->pg_init_delay_msecs
!= DM_PG_INIT_DELAY_DEFAULT
)
1647 DMEMIT("pg_init_delay_msecs %u ", m
->pg_init_delay_msecs
);
1648 if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER
, &m
->flags
))
1649 DMEMIT("retain_attached_hw_handler ");
1650 if (m
->queue_mode
!= DM_TYPE_REQUEST_BASED
) {
1651 switch(m
->queue_mode
) {
1652 case DM_TYPE_BIO_BASED
:
1653 DMEMIT("queue_mode bio ");
1655 case DM_TYPE_MQ_REQUEST_BASED
:
1656 DMEMIT("queue_mode mq ");
1665 if (!m
->hw_handler_name
|| type
== STATUSTYPE_INFO
)
1668 DMEMIT("1 %s ", m
->hw_handler_name
);
1670 DMEMIT("%u ", m
->nr_priority_groups
);
1673 pg_num
= m
->next_pg
->pg_num
;
1674 else if (m
->current_pg
)
1675 pg_num
= m
->current_pg
->pg_num
;
1677 pg_num
= (m
->nr_priority_groups
? 1 : 0);
1679 DMEMIT("%u ", pg_num
);
1682 case STATUSTYPE_INFO
:
1683 list_for_each_entry(pg
, &m
->priority_groups
, list
) {
1685 state
= 'D'; /* Disabled */
1686 else if (pg
== m
->current_pg
)
1687 state
= 'A'; /* Currently Active */
1689 state
= 'E'; /* Enabled */
1691 DMEMIT("%c ", state
);
1693 if (pg
->ps
.type
->status
)
1694 sz
+= pg
->ps
.type
->status(&pg
->ps
, NULL
, type
,
1700 DMEMIT("%u %u ", pg
->nr_pgpaths
,
1701 pg
->ps
.type
->info_args
);
1703 list_for_each_entry(p
, &pg
->pgpaths
, list
) {
1704 DMEMIT("%s %s %u ", p
->path
.dev
->name
,
1705 p
->is_active
? "A" : "F",
1707 if (pg
->ps
.type
->status
)
1708 sz
+= pg
->ps
.type
->status(&pg
->ps
,
1709 &p
->path
, type
, result
+ sz
,
1715 case STATUSTYPE_TABLE
:
1716 list_for_each_entry(pg
, &m
->priority_groups
, list
) {
1717 DMEMIT("%s ", pg
->ps
.type
->name
);
1719 if (pg
->ps
.type
->status
)
1720 sz
+= pg
->ps
.type
->status(&pg
->ps
, NULL
, type
,
1726 DMEMIT("%u %u ", pg
->nr_pgpaths
,
1727 pg
->ps
.type
->table_args
);
1729 list_for_each_entry(p
, &pg
->pgpaths
, list
) {
1730 DMEMIT("%s ", p
->path
.dev
->name
);
1731 if (pg
->ps
.type
->status
)
1732 sz
+= pg
->ps
.type
->status(&pg
->ps
,
1733 &p
->path
, type
, result
+ sz
,
1740 spin_unlock_irqrestore(&m
->lock
, flags
);
1743 static int multipath_message(struct dm_target
*ti
, unsigned argc
, char **argv
)
1747 struct multipath
*m
= ti
->private;
1750 mutex_lock(&m
->work_mutex
);
1752 if (dm_suspended(ti
)) {
1758 if (!strcasecmp(argv
[0], "queue_if_no_path")) {
1759 r
= queue_if_no_path(m
, true, false);
1761 } else if (!strcasecmp(argv
[0], "fail_if_no_path")) {
1762 r
= queue_if_no_path(m
, false, false);
1768 DMWARN("Invalid multipath message arguments. Expected 2 arguments, got %d.", argc
);
1772 if (!strcasecmp(argv
[0], "disable_group")) {
1773 r
= bypass_pg_num(m
, argv
[1], true);
1775 } else if (!strcasecmp(argv
[0], "enable_group")) {
1776 r
= bypass_pg_num(m
, argv
[1], false);
1778 } else if (!strcasecmp(argv
[0], "switch_group")) {
1779 r
= switch_pg_num(m
, argv
[1]);
1781 } else if (!strcasecmp(argv
[0], "reinstate_path"))
1782 action
= reinstate_path
;
1783 else if (!strcasecmp(argv
[0], "fail_path"))
1786 DMWARN("Unrecognised multipath message received: %s", argv
[0]);
1790 r
= dm_get_device(ti
, argv
[1], dm_table_get_mode(ti
->table
), &dev
);
1792 DMWARN("message: error getting device %s",
1797 r
= action_dev(m
, dev
, action
);
1799 dm_put_device(ti
, dev
);
1802 mutex_unlock(&m
->work_mutex
);
1806 static int multipath_prepare_ioctl(struct dm_target
*ti
,
1807 struct block_device
**bdev
, fmode_t
*mode
)
1809 struct multipath
*m
= ti
->private;
1810 struct pgpath
*current_pgpath
;
1813 current_pgpath
= lockless_dereference(m
->current_pgpath
);
1814 if (!current_pgpath
)
1815 current_pgpath
= choose_pgpath(m
, 0);
1817 if (current_pgpath
) {
1818 if (!test_bit(MPATHF_QUEUE_IO
, &m
->flags
)) {
1819 *bdev
= current_pgpath
->path
.dev
->bdev
;
1820 *mode
= current_pgpath
->path
.dev
->mode
;
1823 /* pg_init has not started or completed */
1827 /* No path is available */
1828 if (test_bit(MPATHF_QUEUE_IF_NO_PATH
, &m
->flags
))
1834 if (r
== -ENOTCONN
) {
1835 if (!lockless_dereference(m
->current_pg
)) {
1836 /* Path status changed, redo selection */
1837 (void) choose_pgpath(m
, 0);
1839 if (test_bit(MPATHF_PG_INIT_REQUIRED
, &m
->flags
))
1840 pg_init_all_paths(m
);
1841 dm_table_run_md_queue_async(m
->ti
->table
);
1842 process_queued_io_list(m
);
1846 * Only pass ioctls through if the device sizes match exactly.
1848 if (!r
&& ti
->len
!= i_size_read((*bdev
)->bd_inode
) >> SECTOR_SHIFT
)
1853 static int multipath_iterate_devices(struct dm_target
*ti
,
1854 iterate_devices_callout_fn fn
, void *data
)
1856 struct multipath
*m
= ti
->private;
1857 struct priority_group
*pg
;
1861 list_for_each_entry(pg
, &m
->priority_groups
, list
) {
1862 list_for_each_entry(p
, &pg
->pgpaths
, list
) {
1863 ret
= fn(ti
, p
->path
.dev
, ti
->begin
, ti
->len
, data
);
1873 static int pgpath_busy(struct pgpath
*pgpath
)
1875 struct request_queue
*q
= bdev_get_queue(pgpath
->path
.dev
->bdev
);
1877 return blk_lld_busy(q
);
1881 * We return "busy", only when we can map I/Os but underlying devices
1882 * are busy (so even if we map I/Os now, the I/Os will wait on
1883 * the underlying queue).
1884 * In other words, if we want to kill I/Os or queue them inside us
1885 * due to map unavailability, we don't return "busy". Otherwise,
1886 * dm core won't give us the I/Os and we can't do what we want.
1888 static int multipath_busy(struct dm_target
*ti
)
1890 bool busy
= false, has_active
= false;
1891 struct multipath
*m
= ti
->private;
1892 struct priority_group
*pg
, *next_pg
;
1893 struct pgpath
*pgpath
;
1895 /* pg_init in progress */
1896 if (atomic_read(&m
->pg_init_in_progress
))
1899 /* no paths available, for blk-mq: rely on IO mapping to delay requeue */
1900 if (!atomic_read(&m
->nr_valid_paths
) && test_bit(MPATHF_QUEUE_IF_NO_PATH
, &m
->flags
))
1901 return (m
->queue_mode
!= DM_TYPE_MQ_REQUEST_BASED
);
1903 /* Guess which priority_group will be used at next mapping time */
1904 pg
= lockless_dereference(m
->current_pg
);
1905 next_pg
= lockless_dereference(m
->next_pg
);
1906 if (unlikely(!lockless_dereference(m
->current_pgpath
) && next_pg
))
1911 * We don't know which pg will be used at next mapping time.
1912 * We don't call choose_pgpath() here to avoid to trigger
1913 * pg_init just by busy checking.
1914 * So we don't know whether underlying devices we will be using
1915 * at next mapping time are busy or not. Just try mapping.
1921 * If there is one non-busy active path at least, the path selector
1922 * will be able to select it. So we consider such a pg as not busy.
1925 list_for_each_entry(pgpath
, &pg
->pgpaths
, list
) {
1926 if (pgpath
->is_active
) {
1928 if (!pgpath_busy(pgpath
)) {
1937 * No active path in this pg, so this pg won't be used and
1938 * the current_pg will be changed at next mapping time.
1939 * We need to try mapping to determine it.
1947 /*-----------------------------------------------------------------
1949 *---------------------------------------------------------------*/
1950 static struct target_type multipath_target
= {
1951 .name
= "multipath",
1952 .version
= {1, 12, 0},
1953 .features
= DM_TARGET_SINGLETON
| DM_TARGET_IMMUTABLE
,
1954 .module
= THIS_MODULE
,
1955 .ctr
= multipath_ctr
,
1956 .dtr
= multipath_dtr
,
1957 .clone_and_map_rq
= multipath_clone_and_map
,
1958 .release_clone_rq
= multipath_release_clone
,
1959 .rq_end_io
= multipath_end_io
,
1960 .map
= multipath_map_bio
,
1961 .end_io
= multipath_end_io_bio
,
1962 .presuspend
= multipath_presuspend
,
1963 .postsuspend
= multipath_postsuspend
,
1964 .resume
= multipath_resume
,
1965 .status
= multipath_status
,
1966 .message
= multipath_message
,
1967 .prepare_ioctl
= multipath_prepare_ioctl
,
1968 .iterate_devices
= multipath_iterate_devices
,
1969 .busy
= multipath_busy
,
1972 static int __init
dm_multipath_init(void)
1976 r
= dm_register_target(&multipath_target
);
1978 DMERR("request-based register failed %d", r
);
1980 goto bad_register_target
;
1983 kmultipathd
= alloc_workqueue("kmpathd", WQ_MEM_RECLAIM
, 0);
1985 DMERR("failed to create workqueue kmpathd");
1987 goto bad_alloc_kmultipathd
;
1991 * A separate workqueue is used to handle the device handlers
1992 * to avoid overloading existing workqueue. Overloading the
1993 * old workqueue would also create a bottleneck in the
1994 * path of the storage hardware device activation.
1996 kmpath_handlerd
= alloc_ordered_workqueue("kmpath_handlerd",
1998 if (!kmpath_handlerd
) {
1999 DMERR("failed to create workqueue kmpath_handlerd");
2001 goto bad_alloc_kmpath_handlerd
;
2006 bad_alloc_kmpath_handlerd
:
2007 destroy_workqueue(kmultipathd
);
2008 bad_alloc_kmultipathd
:
2009 dm_unregister_target(&multipath_target
);
2010 bad_register_target
:
2014 static void __exit
dm_multipath_exit(void)
2016 destroy_workqueue(kmpath_handlerd
);
2017 destroy_workqueue(kmultipathd
);
2019 dm_unregister_target(&multipath_target
);
2022 module_init(dm_multipath_init
);
2023 module_exit(dm_multipath_exit
);
2025 MODULE_DESCRIPTION(DM_NAME
" multipath target");
2026 MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
2027 MODULE_LICENSE("GPL");