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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2003 Sistina Software Limited.
4 * Copyright (C) 2004-2005 Red Hat, Inc. All rights reserved.
5 *
6 * This file is released under the GPL.
7 */
8
9#include <linux/device-mapper.h>
10
11#include "dm-rq.h"
12#include "dm-bio-record.h"
13#include "dm-path-selector.h"
14#include "dm-uevent.h"
15
16#include <linux/blkdev.h>
17#include <linux/ctype.h>
18#include <linux/init.h>
19#include <linux/mempool.h>
20#include <linux/module.h>
21#include <linux/pagemap.h>
22#include <linux/slab.h>
23#include <linux/time.h>
24#include <linux/timer.h>
25#include <linux/workqueue.h>
26#include <linux/delay.h>
27#include <scsi/scsi_dh.h>
28#include <linux/atomic.h>
29#include <linux/blk-mq.h>
30
31static struct workqueue_struct *dm_mpath_wq;
32
33#define DM_MSG_PREFIX "multipath"
34#define DM_PG_INIT_DELAY_MSECS 2000
35#define DM_PG_INIT_DELAY_DEFAULT ((unsigned int) -1)
36#define QUEUE_IF_NO_PATH_TIMEOUT_DEFAULT 0
37
38static unsigned long queue_if_no_path_timeout_secs = QUEUE_IF_NO_PATH_TIMEOUT_DEFAULT;
39
40/* Path properties */
41struct pgpath {
42 struct list_head list;
43
44 struct priority_group *pg; /* Owning PG */
45 unsigned int fail_count; /* Cumulative failure count */
46
47 struct dm_path path;
48 struct delayed_work activate_path;
49
50 bool is_active:1; /* Path status */
51};
52
53#define path_to_pgpath(__pgp) container_of((__pgp), struct pgpath, path)
54
55/*
56 * Paths are grouped into Priority Groups and numbered from 1 upwards.
57 * Each has a path selector which controls which path gets used.
58 */
59struct priority_group {
60 struct list_head list;
61
62 struct multipath *m; /* Owning multipath instance */
63 struct path_selector ps;
64
65 unsigned int pg_num; /* Reference number */
66 unsigned int nr_pgpaths; /* Number of paths in PG */
67 struct list_head pgpaths;
68
69 bool bypassed:1; /* Temporarily bypass this PG? */
70};
71
72/* Multipath context */
73struct multipath {
74 unsigned long flags; /* Multipath state flags */
75
76 spinlock_t lock;
77 enum dm_queue_mode queue_mode;
78
79 struct pgpath *current_pgpath;
80 struct priority_group *current_pg;
81 struct priority_group *next_pg; /* Switch to this PG if set */
82
83 atomic_t nr_valid_paths; /* Total number of usable paths */
84 unsigned int nr_priority_groups;
85 struct list_head priority_groups;
86
87 const char *hw_handler_name;
88 char *hw_handler_params;
89 wait_queue_head_t pg_init_wait; /* Wait for pg_init completion */
90 unsigned int pg_init_retries; /* Number of times to retry pg_init */
91 unsigned int pg_init_delay_msecs; /* Number of msecs before pg_init retry */
92 atomic_t pg_init_in_progress; /* Only one pg_init allowed at once */
93 atomic_t pg_init_count; /* Number of times pg_init called */
94
95 struct mutex work_mutex;
96 struct work_struct trigger_event;
97 struct dm_target *ti;
98
99 struct work_struct process_queued_bios;
100 struct bio_list queued_bios;
101
102 struct timer_list nopath_timer; /* Timeout for queue_if_no_path */
103};
104
105/*
106 * Context information attached to each io we process.
107 */
108struct dm_mpath_io {
109 struct pgpath *pgpath;
110 size_t nr_bytes;
111 u64 start_time_ns;
112};
113
114typedef int (*action_fn) (struct pgpath *pgpath);
115
116static struct workqueue_struct *kmultipathd, *kmpath_handlerd;
117static void trigger_event(struct work_struct *work);
118static void activate_or_offline_path(struct pgpath *pgpath);
119static void activate_path_work(struct work_struct *work);
120static void process_queued_bios(struct work_struct *work);
121static void queue_if_no_path_timeout_work(struct timer_list *t);
122
123/*
124 *-----------------------------------------------
125 * Multipath state flags.
126 *-----------------------------------------------
127 */
128#define MPATHF_QUEUE_IO 0 /* Must we queue all I/O? */
129#define MPATHF_QUEUE_IF_NO_PATH 1 /* Queue I/O if last path fails? */
130#define MPATHF_SAVED_QUEUE_IF_NO_PATH 2 /* Saved state during suspension */
131#define MPATHF_RETAIN_ATTACHED_HW_HANDLER 3 /* If there's already a hw_handler present, don't change it. */
132#define MPATHF_PG_INIT_DISABLED 4 /* pg_init is not currently allowed */
133#define MPATHF_PG_INIT_REQUIRED 5 /* pg_init needs calling? */
134#define MPATHF_PG_INIT_DELAY_RETRY 6 /* Delay pg_init retry? */
135
136static bool mpath_double_check_test_bit(int MPATHF_bit, struct multipath *m)
137{
138 bool r = test_bit(MPATHF_bit, &m->flags);
139
140 if (r) {
141 unsigned long flags;
142
143 spin_lock_irqsave(&m->lock, flags);
144 r = test_bit(MPATHF_bit, &m->flags);
145 spin_unlock_irqrestore(&m->lock, flags);
146 }
147
148 return r;
149}
150
151/*
152 *-----------------------------------------------
153 * Allocation routines
154 *-----------------------------------------------
155 */
156static struct pgpath *alloc_pgpath(void)
157{
158 struct pgpath *pgpath = kzalloc(sizeof(*pgpath), GFP_KERNEL);
159
160 if (!pgpath)
161 return NULL;
162
163 pgpath->is_active = true;
164
165 return pgpath;
166}
167
168static void free_pgpath(struct pgpath *pgpath)
169{
170 kfree(pgpath);
171}
172
173static struct priority_group *alloc_priority_group(void)
174{
175 struct priority_group *pg;
176
177 pg = kzalloc(sizeof(*pg), GFP_KERNEL);
178
179 if (pg)
180 INIT_LIST_HEAD(&pg->pgpaths);
181
182 return pg;
183}
184
185static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti)
186{
187 struct pgpath *pgpath, *tmp;
188
189 list_for_each_entry_safe(pgpath, tmp, pgpaths, list) {
190 list_del(&pgpath->list);
191 dm_put_device(ti, pgpath->path.dev);
192 free_pgpath(pgpath);
193 }
194}
195
196static void free_priority_group(struct priority_group *pg,
197 struct dm_target *ti)
198{
199 struct path_selector *ps = &pg->ps;
200
201 if (ps->type) {
202 ps->type->destroy(ps);
203 dm_put_path_selector(ps->type);
204 }
205
206 free_pgpaths(&pg->pgpaths, ti);
207 kfree(pg);
208}
209
210static struct multipath *alloc_multipath(struct dm_target *ti)
211{
212 struct multipath *m;
213
214 m = kzalloc(sizeof(*m), GFP_KERNEL);
215 if (m) {
216 INIT_LIST_HEAD(&m->priority_groups);
217 spin_lock_init(&m->lock);
218 atomic_set(&m->nr_valid_paths, 0);
219 INIT_WORK(&m->trigger_event, trigger_event);
220 mutex_init(&m->work_mutex);
221
222 m->queue_mode = DM_TYPE_NONE;
223
224 m->ti = ti;
225 ti->private = m;
226
227 timer_setup(&m->nopath_timer, queue_if_no_path_timeout_work, 0);
228 }
229
230 return m;
231}
232
233static int alloc_multipath_stage2(struct dm_target *ti, struct multipath *m)
234{
235 if (m->queue_mode == DM_TYPE_NONE) {
236 m->queue_mode = DM_TYPE_REQUEST_BASED;
237 } else if (m->queue_mode == DM_TYPE_BIO_BASED) {
238 INIT_WORK(&m->process_queued_bios, process_queued_bios);
239 /*
240 * bio-based doesn't support any direct scsi_dh management;
241 * it just discovers if a scsi_dh is attached.
242 */
243 set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags);
244 }
245
246 dm_table_set_type(ti->table, m->queue_mode);
247
248 /*
249 * Init fields that are only used when a scsi_dh is attached
250 * - must do this unconditionally (really doesn't hurt non-SCSI uses)
251 */
252 set_bit(MPATHF_QUEUE_IO, &m->flags);
253 atomic_set(&m->pg_init_in_progress, 0);
254 atomic_set(&m->pg_init_count, 0);
255 m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT;
256 init_waitqueue_head(&m->pg_init_wait);
257
258 return 0;
259}
260
261static void free_multipath(struct multipath *m)
262{
263 struct priority_group *pg, *tmp;
264
265 list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) {
266 list_del(&pg->list);
267 free_priority_group(pg, m->ti);
268 }
269
270 kfree(m->hw_handler_name);
271 kfree(m->hw_handler_params);
272 mutex_destroy(&m->work_mutex);
273 kfree(m);
274}
275
276static struct dm_mpath_io *get_mpio(union map_info *info)
277{
278 return info->ptr;
279}
280
281static size_t multipath_per_bio_data_size(void)
282{
283 return sizeof(struct dm_mpath_io) + sizeof(struct dm_bio_details);
284}
285
286static struct dm_mpath_io *get_mpio_from_bio(struct bio *bio)
287{
288 return dm_per_bio_data(bio, multipath_per_bio_data_size());
289}
290
291static struct dm_bio_details *get_bio_details_from_mpio(struct dm_mpath_io *mpio)
292{
293 /* dm_bio_details is immediately after the dm_mpath_io in bio's per-bio-data */
294 void *bio_details = mpio + 1;
295 return bio_details;
296}
297
298static void multipath_init_per_bio_data(struct bio *bio, struct dm_mpath_io **mpio_p)
299{
300 struct dm_mpath_io *mpio = get_mpio_from_bio(bio);
301 struct dm_bio_details *bio_details = get_bio_details_from_mpio(mpio);
302
303 mpio->nr_bytes = bio->bi_iter.bi_size;
304 mpio->pgpath = NULL;
305 mpio->start_time_ns = 0;
306 *mpio_p = mpio;
307
308 dm_bio_record(bio_details, bio);
309}
310
311/*
312 *-----------------------------------------------
313 * Path selection
314 *-----------------------------------------------
315 */
316static int __pg_init_all_paths(struct multipath *m)
317{
318 struct pgpath *pgpath;
319 unsigned long pg_init_delay = 0;
320
321 lockdep_assert_held(&m->lock);
322
323 if (atomic_read(&m->pg_init_in_progress) || test_bit(MPATHF_PG_INIT_DISABLED, &m->flags))
324 return 0;
325
326 atomic_inc(&m->pg_init_count);
327 clear_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
328
329 /* Check here to reset pg_init_required */
330 if (!m->current_pg)
331 return 0;
332
333 if (test_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags))
334 pg_init_delay = msecs_to_jiffies(m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT ?
335 m->pg_init_delay_msecs : DM_PG_INIT_DELAY_MSECS);
336 list_for_each_entry(pgpath, &m->current_pg->pgpaths, list) {
337 /* Skip failed paths */
338 if (!pgpath->is_active)
339 continue;
340 if (queue_delayed_work(kmpath_handlerd, &pgpath->activate_path,
341 pg_init_delay))
342 atomic_inc(&m->pg_init_in_progress);
343 }
344 return atomic_read(&m->pg_init_in_progress);
345}
346
347static int pg_init_all_paths(struct multipath *m)
348{
349 int ret;
350 unsigned long flags;
351
352 spin_lock_irqsave(&m->lock, flags);
353 ret = __pg_init_all_paths(m);
354 spin_unlock_irqrestore(&m->lock, flags);
355
356 return ret;
357}
358
359static void __switch_pg(struct multipath *m, struct priority_group *pg)
360{
361 lockdep_assert_held(&m->lock);
362
363 m->current_pg = pg;
364
365 /* Must we initialise the PG first, and queue I/O till it's ready? */
366 if (m->hw_handler_name) {
367 set_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
368 set_bit(MPATHF_QUEUE_IO, &m->flags);
369 } else {
370 clear_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
371 clear_bit(MPATHF_QUEUE_IO, &m->flags);
372 }
373
374 atomic_set(&m->pg_init_count, 0);
375}
376
377static struct pgpath *choose_path_in_pg(struct multipath *m,
378 struct priority_group *pg,
379 size_t nr_bytes)
380{
381 unsigned long flags;
382 struct dm_path *path;
383 struct pgpath *pgpath;
384
385 path = pg->ps.type->select_path(&pg->ps, nr_bytes);
386 if (!path)
387 return ERR_PTR(-ENXIO);
388
389 pgpath = path_to_pgpath(path);
390
391 if (unlikely(READ_ONCE(m->current_pg) != pg)) {
392 /* Only update current_pgpath if pg changed */
393 spin_lock_irqsave(&m->lock, flags);
394 m->current_pgpath = pgpath;
395 __switch_pg(m, pg);
396 spin_unlock_irqrestore(&m->lock, flags);
397 }
398
399 return pgpath;
400}
401
402static struct pgpath *choose_pgpath(struct multipath *m, size_t nr_bytes)
403{
404 unsigned long flags;
405 struct priority_group *pg;
406 struct pgpath *pgpath;
407 unsigned int bypassed = 1;
408
409 if (!atomic_read(&m->nr_valid_paths)) {
410 spin_lock_irqsave(&m->lock, flags);
411 clear_bit(MPATHF_QUEUE_IO, &m->flags);
412 spin_unlock_irqrestore(&m->lock, flags);
413 goto failed;
414 }
415
416 /* Were we instructed to switch PG? */
417 if (READ_ONCE(m->next_pg)) {
418 spin_lock_irqsave(&m->lock, flags);
419 pg = m->next_pg;
420 if (!pg) {
421 spin_unlock_irqrestore(&m->lock, flags);
422 goto check_current_pg;
423 }
424 m->next_pg = NULL;
425 spin_unlock_irqrestore(&m->lock, flags);
426 pgpath = choose_path_in_pg(m, pg, nr_bytes);
427 if (!IS_ERR_OR_NULL(pgpath))
428 return pgpath;
429 }
430
431 /* Don't change PG until it has no remaining paths */
432check_current_pg:
433 pg = READ_ONCE(m->current_pg);
434 if (pg) {
435 pgpath = choose_path_in_pg(m, pg, nr_bytes);
436 if (!IS_ERR_OR_NULL(pgpath))
437 return pgpath;
438 }
439
440 /*
441 * Loop through priority groups until we find a valid path.
442 * First time we skip PGs marked 'bypassed'.
443 * Second time we only try the ones we skipped, but set
444 * pg_init_delay_retry so we do not hammer controllers.
445 */
446 do {
447 list_for_each_entry(pg, &m->priority_groups, list) {
448 if (pg->bypassed == !!bypassed)
449 continue;
450 pgpath = choose_path_in_pg(m, pg, nr_bytes);
451 if (!IS_ERR_OR_NULL(pgpath)) {
452 if (!bypassed) {
453 spin_lock_irqsave(&m->lock, flags);
454 set_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
455 spin_unlock_irqrestore(&m->lock, flags);
456 }
457 return pgpath;
458 }
459 }
460 } while (bypassed--);
461
462failed:
463 spin_lock_irqsave(&m->lock, flags);
464 m->current_pgpath = NULL;
465 m->current_pg = NULL;
466 spin_unlock_irqrestore(&m->lock, flags);
467
468 return NULL;
469}
470
471/*
472 * dm_report_EIO() is a macro instead of a function to make pr_debug_ratelimited()
473 * report the function name and line number of the function from which
474 * it has been invoked.
475 */
476#define dm_report_EIO(m) \
477 DMDEBUG_LIMIT("%s: returning EIO; QIFNP = %d; SQIFNP = %d; DNFS = %d", \
478 dm_table_device_name((m)->ti->table), \
479 test_bit(MPATHF_QUEUE_IF_NO_PATH, &(m)->flags), \
480 test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &(m)->flags), \
481 dm_noflush_suspending((m)->ti))
482
483/*
484 * Check whether bios must be queued in the device-mapper core rather
485 * than here in the target.
486 */
487static bool __must_push_back(struct multipath *m)
488{
489 return dm_noflush_suspending(m->ti);
490}
491
492static bool must_push_back_rq(struct multipath *m)
493{
494 unsigned long flags;
495 bool ret;
496
497 spin_lock_irqsave(&m->lock, flags);
498 ret = (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) || __must_push_back(m));
499 spin_unlock_irqrestore(&m->lock, flags);
500
501 return ret;
502}
503
504/*
505 * Map cloned requests (request-based multipath)
506 */
507static int multipath_clone_and_map(struct dm_target *ti, struct request *rq,
508 union map_info *map_context,
509 struct request **__clone)
510{
511 struct multipath *m = ti->private;
512 size_t nr_bytes = blk_rq_bytes(rq);
513 struct pgpath *pgpath;
514 struct block_device *bdev;
515 struct dm_mpath_io *mpio = get_mpio(map_context);
516 struct request_queue *q;
517 struct request *clone;
518
519 /* Do we need to select a new pgpath? */
520 pgpath = READ_ONCE(m->current_pgpath);
521 if (!pgpath || !mpath_double_check_test_bit(MPATHF_QUEUE_IO, m))
522 pgpath = choose_pgpath(m, nr_bytes);
523
524 if (!pgpath) {
525 if (must_push_back_rq(m))
526 return DM_MAPIO_DELAY_REQUEUE;
527 dm_report_EIO(m); /* Failed */
528 return DM_MAPIO_KILL;
529 } else if (mpath_double_check_test_bit(MPATHF_QUEUE_IO, m) ||
530 mpath_double_check_test_bit(MPATHF_PG_INIT_REQUIRED, m)) {
531 pg_init_all_paths(m);
532 return DM_MAPIO_DELAY_REQUEUE;
533 }
534
535 mpio->pgpath = pgpath;
536 mpio->nr_bytes = nr_bytes;
537
538 bdev = pgpath->path.dev->bdev;
539 q = bdev_get_queue(bdev);
540 clone = blk_mq_alloc_request(q, rq->cmd_flags | REQ_NOMERGE,
541 BLK_MQ_REQ_NOWAIT);
542 if (IS_ERR(clone)) {
543 /* EBUSY, ENODEV or EWOULDBLOCK: requeue */
544 if (blk_queue_dying(q)) {
545 atomic_inc(&m->pg_init_in_progress);
546 activate_or_offline_path(pgpath);
547 return DM_MAPIO_DELAY_REQUEUE;
548 }
549
550 /*
551 * blk-mq's SCHED_RESTART can cover this requeue, so we
552 * needn't deal with it by DELAY_REQUEUE. More importantly,
553 * we have to return DM_MAPIO_REQUEUE so that blk-mq can
554 * get the queue busy feedback (via BLK_STS_RESOURCE),
555 * otherwise I/O merging can suffer.
556 */
557 return DM_MAPIO_REQUEUE;
558 }
559 clone->bio = clone->biotail = NULL;
560 clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
561 *__clone = clone;
562
563 if (pgpath->pg->ps.type->start_io)
564 pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
565 &pgpath->path,
566 nr_bytes);
567 return DM_MAPIO_REMAPPED;
568}
569
570static void multipath_release_clone(struct request *clone,
571 union map_info *map_context)
572{
573 if (unlikely(map_context)) {
574 /*
575 * non-NULL map_context means caller is still map
576 * method; must undo multipath_clone_and_map()
577 */
578 struct dm_mpath_io *mpio = get_mpio(map_context);
579 struct pgpath *pgpath = mpio->pgpath;
580
581 if (pgpath && pgpath->pg->ps.type->end_io)
582 pgpath->pg->ps.type->end_io(&pgpath->pg->ps,
583 &pgpath->path,
584 mpio->nr_bytes,
585 clone->io_start_time_ns);
586 }
587
588 blk_mq_free_request(clone);
589}
590
591/*
592 * Map cloned bios (bio-based multipath)
593 */
594
595static void __multipath_queue_bio(struct multipath *m, struct bio *bio)
596{
597 /* Queue for the daemon to resubmit */
598 bio_list_add(&m->queued_bios, bio);
599 if (!test_bit(MPATHF_QUEUE_IO, &m->flags))
600 queue_work(kmultipathd, &m->process_queued_bios);
601}
602
603static void multipath_queue_bio(struct multipath *m, struct bio *bio)
604{
605 unsigned long flags;
606
607 spin_lock_irqsave(&m->lock, flags);
608 __multipath_queue_bio(m, bio);
609 spin_unlock_irqrestore(&m->lock, flags);
610}
611
612static struct pgpath *__map_bio(struct multipath *m, struct bio *bio)
613{
614 struct pgpath *pgpath;
615 unsigned long flags;
616
617 /* Do we need to select a new pgpath? */
618 pgpath = READ_ONCE(m->current_pgpath);
619 if (!pgpath || !mpath_double_check_test_bit(MPATHF_QUEUE_IO, m))
620 pgpath = choose_pgpath(m, bio->bi_iter.bi_size);
621
622 if (!pgpath) {
623 spin_lock_irqsave(&m->lock, flags);
624 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
625 __multipath_queue_bio(m, bio);
626 pgpath = ERR_PTR(-EAGAIN);
627 }
628 spin_unlock_irqrestore(&m->lock, flags);
629
630 } else if (mpath_double_check_test_bit(MPATHF_QUEUE_IO, m) ||
631 mpath_double_check_test_bit(MPATHF_PG_INIT_REQUIRED, m)) {
632 multipath_queue_bio(m, bio);
633 pg_init_all_paths(m);
634 return ERR_PTR(-EAGAIN);
635 }
636
637 return pgpath;
638}
639
640static int __multipath_map_bio(struct multipath *m, struct bio *bio,
641 struct dm_mpath_io *mpio)
642{
643 struct pgpath *pgpath = __map_bio(m, bio);
644
645 if (IS_ERR(pgpath))
646 return DM_MAPIO_SUBMITTED;
647
648 if (!pgpath) {
649 if (__must_push_back(m))
650 return DM_MAPIO_REQUEUE;
651 dm_report_EIO(m);
652 return DM_MAPIO_KILL;
653 }
654
655 mpio->pgpath = pgpath;
656
657 if (dm_ps_use_hr_timer(pgpath->pg->ps.type))
658 mpio->start_time_ns = ktime_get_ns();
659
660 bio->bi_status = 0;
661 bio_set_dev(bio, pgpath->path.dev->bdev);
662 bio->bi_opf |= REQ_FAILFAST_TRANSPORT;
663
664 if (pgpath->pg->ps.type->start_io)
665 pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
666 &pgpath->path,
667 mpio->nr_bytes);
668 return DM_MAPIO_REMAPPED;
669}
670
671static int multipath_map_bio(struct dm_target *ti, struct bio *bio)
672{
673 struct multipath *m = ti->private;
674 struct dm_mpath_io *mpio = NULL;
675
676 multipath_init_per_bio_data(bio, &mpio);
677 return __multipath_map_bio(m, bio, mpio);
678}
679
680static void process_queued_io_list(struct multipath *m)
681{
682 if (m->queue_mode == DM_TYPE_REQUEST_BASED)
683 dm_mq_kick_requeue_list(dm_table_get_md(m->ti->table));
684 else if (m->queue_mode == DM_TYPE_BIO_BASED)
685 queue_work(kmultipathd, &m->process_queued_bios);
686}
687
688static void process_queued_bios(struct work_struct *work)
689{
690 int r;
691 unsigned long flags;
692 struct bio *bio;
693 struct bio_list bios;
694 struct blk_plug plug;
695 struct multipath *m =
696 container_of(work, struct multipath, process_queued_bios);
697
698 bio_list_init(&bios);
699
700 spin_lock_irqsave(&m->lock, flags);
701
702 if (bio_list_empty(&m->queued_bios)) {
703 spin_unlock_irqrestore(&m->lock, flags);
704 return;
705 }
706
707 bio_list_merge_init(&bios, &m->queued_bios);
708
709 spin_unlock_irqrestore(&m->lock, flags);
710
711 blk_start_plug(&plug);
712 while ((bio = bio_list_pop(&bios))) {
713 struct dm_mpath_io *mpio = get_mpio_from_bio(bio);
714
715 dm_bio_restore(get_bio_details_from_mpio(mpio), bio);
716 r = __multipath_map_bio(m, bio, mpio);
717 switch (r) {
718 case DM_MAPIO_KILL:
719 bio->bi_status = BLK_STS_IOERR;
720 bio_endio(bio);
721 break;
722 case DM_MAPIO_REQUEUE:
723 bio->bi_status = BLK_STS_DM_REQUEUE;
724 bio_endio(bio);
725 break;
726 case DM_MAPIO_REMAPPED:
727 submit_bio_noacct(bio);
728 break;
729 case DM_MAPIO_SUBMITTED:
730 break;
731 default:
732 WARN_ONCE(true, "__multipath_map_bio() returned %d\n", r);
733 }
734 }
735 blk_finish_plug(&plug);
736}
737
738/*
739 * If we run out of usable paths, should we queue I/O or error it?
740 */
741static int queue_if_no_path(struct multipath *m, bool f_queue_if_no_path,
742 bool save_old_value, const char *caller)
743{
744 unsigned long flags;
745 bool queue_if_no_path_bit, saved_queue_if_no_path_bit;
746 const char *dm_dev_name = dm_table_device_name(m->ti->table);
747
748 DMDEBUG("%s: %s caller=%s f_queue_if_no_path=%d save_old_value=%d",
749 dm_dev_name, __func__, caller, f_queue_if_no_path, save_old_value);
750
751 spin_lock_irqsave(&m->lock, flags);
752
753 queue_if_no_path_bit = test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
754 saved_queue_if_no_path_bit = test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
755
756 if (save_old_value) {
757 if (unlikely(!queue_if_no_path_bit && saved_queue_if_no_path_bit)) {
758 DMERR("%s: QIFNP disabled but saved as enabled, saving again loses state, not saving!",
759 dm_dev_name);
760 } else
761 assign_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags, queue_if_no_path_bit);
762 } else if (!f_queue_if_no_path && saved_queue_if_no_path_bit) {
763 /* due to "fail_if_no_path" message, need to honor it. */
764 clear_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
765 }
766 assign_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags, f_queue_if_no_path);
767
768 DMDEBUG("%s: after %s changes; QIFNP = %d; SQIFNP = %d; DNFS = %d",
769 dm_dev_name, __func__,
770 test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags),
771 test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags),
772 dm_noflush_suspending(m->ti));
773
774 spin_unlock_irqrestore(&m->lock, flags);
775
776 if (!f_queue_if_no_path) {
777 dm_table_run_md_queue_async(m->ti->table);
778 process_queued_io_list(m);
779 }
780
781 return 0;
782}
783
784/*
785 * If the queue_if_no_path timeout fires, turn off queue_if_no_path and
786 * process any queued I/O.
787 */
788static void queue_if_no_path_timeout_work(struct timer_list *t)
789{
790 struct multipath *m = from_timer(m, t, nopath_timer);
791
792 DMWARN("queue_if_no_path timeout on %s, failing queued IO",
793 dm_table_device_name(m->ti->table));
794 queue_if_no_path(m, false, false, __func__);
795}
796
797/*
798 * Enable the queue_if_no_path timeout if necessary.
799 * Called with m->lock held.
800 */
801static void enable_nopath_timeout(struct multipath *m)
802{
803 unsigned long queue_if_no_path_timeout =
804 READ_ONCE(queue_if_no_path_timeout_secs) * HZ;
805
806 lockdep_assert_held(&m->lock);
807
808 if (queue_if_no_path_timeout > 0 &&
809 atomic_read(&m->nr_valid_paths) == 0 &&
810 test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
811 mod_timer(&m->nopath_timer,
812 jiffies + queue_if_no_path_timeout);
813 }
814}
815
816static void disable_nopath_timeout(struct multipath *m)
817{
818 del_timer_sync(&m->nopath_timer);
819}
820
821/*
822 * An event is triggered whenever a path is taken out of use.
823 * Includes path failure and PG bypass.
824 */
825static void trigger_event(struct work_struct *work)
826{
827 struct multipath *m =
828 container_of(work, struct multipath, trigger_event);
829
830 dm_table_event(m->ti->table);
831}
832
833/*
834 *---------------------------------------------------------------
835 * Constructor/argument parsing:
836 * <#multipath feature args> [<arg>]*
837 * <#hw_handler args> [hw_handler [<arg>]*]
838 * <#priority groups>
839 * <initial priority group>
840 * [<selector> <#selector args> [<arg>]*
841 * <#paths> <#per-path selector args>
842 * [<path> [<arg>]* ]+ ]+
843 *---------------------------------------------------------------
844 */
845static int parse_path_selector(struct dm_arg_set *as, struct priority_group *pg,
846 struct dm_target *ti)
847{
848 int r;
849 struct path_selector_type *pst;
850 unsigned int ps_argc;
851
852 static const struct dm_arg _args[] = {
853 {0, 1024, "invalid number of path selector args"},
854 };
855
856 pst = dm_get_path_selector(dm_shift_arg(as));
857 if (!pst) {
858 ti->error = "unknown path selector type";
859 return -EINVAL;
860 }
861
862 r = dm_read_arg_group(_args, as, &ps_argc, &ti->error);
863 if (r) {
864 dm_put_path_selector(pst);
865 return -EINVAL;
866 }
867
868 r = pst->create(&pg->ps, ps_argc, as->argv);
869 if (r) {
870 dm_put_path_selector(pst);
871 ti->error = "path selector constructor failed";
872 return r;
873 }
874
875 pg->ps.type = pst;
876 dm_consume_args(as, ps_argc);
877
878 return 0;
879}
880
881static int setup_scsi_dh(struct block_device *bdev, struct multipath *m,
882 const char **attached_handler_name, char **error)
883{
884 struct request_queue *q = bdev_get_queue(bdev);
885 int r;
886
887 if (mpath_double_check_test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, m)) {
888retain:
889 if (*attached_handler_name) {
890 /*
891 * Clear any hw_handler_params associated with a
892 * handler that isn't already attached.
893 */
894 if (m->hw_handler_name && strcmp(*attached_handler_name, m->hw_handler_name)) {
895 kfree(m->hw_handler_params);
896 m->hw_handler_params = NULL;
897 }
898
899 /*
900 * Reset hw_handler_name to match the attached handler
901 *
902 * NB. This modifies the table line to show the actual
903 * handler instead of the original table passed in.
904 */
905 kfree(m->hw_handler_name);
906 m->hw_handler_name = *attached_handler_name;
907 *attached_handler_name = NULL;
908 }
909 }
910
911 if (m->hw_handler_name) {
912 r = scsi_dh_attach(q, m->hw_handler_name);
913 if (r == -EBUSY) {
914 DMINFO("retaining handler on device %pg", bdev);
915 goto retain;
916 }
917 if (r < 0) {
918 *error = "error attaching hardware handler";
919 return r;
920 }
921
922 if (m->hw_handler_params) {
923 r = scsi_dh_set_params(q, m->hw_handler_params);
924 if (r < 0) {
925 *error = "unable to set hardware handler parameters";
926 return r;
927 }
928 }
929 }
930
931 return 0;
932}
933
934static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps,
935 struct dm_target *ti)
936{
937 int r;
938 struct pgpath *p;
939 struct multipath *m = ti->private;
940 struct request_queue *q;
941 const char *attached_handler_name = NULL;
942
943 /* we need at least a path arg */
944 if (as->argc < 1) {
945 ti->error = "no device given";
946 return ERR_PTR(-EINVAL);
947 }
948
949 p = alloc_pgpath();
950 if (!p)
951 return ERR_PTR(-ENOMEM);
952
953 r = dm_get_device(ti, dm_shift_arg(as), dm_table_get_mode(ti->table),
954 &p->path.dev);
955 if (r) {
956 ti->error = "error getting device";
957 goto bad;
958 }
959
960 q = bdev_get_queue(p->path.dev->bdev);
961 attached_handler_name = scsi_dh_attached_handler_name(q, GFP_KERNEL);
962 if (attached_handler_name || m->hw_handler_name) {
963 INIT_DELAYED_WORK(&p->activate_path, activate_path_work);
964 r = setup_scsi_dh(p->path.dev->bdev, m, &attached_handler_name, &ti->error);
965 kfree(attached_handler_name);
966 if (r) {
967 dm_put_device(ti, p->path.dev);
968 goto bad;
969 }
970 }
971
972 r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
973 if (r) {
974 dm_put_device(ti, p->path.dev);
975 goto bad;
976 }
977
978 return p;
979 bad:
980 free_pgpath(p);
981 return ERR_PTR(r);
982}
983
984static struct priority_group *parse_priority_group(struct dm_arg_set *as,
985 struct multipath *m)
986{
987 static const struct dm_arg _args[] = {
988 {1, 1024, "invalid number of paths"},
989 {0, 1024, "invalid number of selector args"}
990 };
991
992 int r;
993 unsigned int i, nr_selector_args, nr_args;
994 struct priority_group *pg;
995 struct dm_target *ti = m->ti;
996
997 if (as->argc < 2) {
998 as->argc = 0;
999 ti->error = "not enough priority group arguments";
1000 return ERR_PTR(-EINVAL);
1001 }
1002
1003 pg = alloc_priority_group();
1004 if (!pg) {
1005 ti->error = "couldn't allocate priority group";
1006 return ERR_PTR(-ENOMEM);
1007 }
1008 pg->m = m;
1009
1010 r = parse_path_selector(as, pg, ti);
1011 if (r)
1012 goto bad;
1013
1014 /*
1015 * read the paths
1016 */
1017 r = dm_read_arg(_args, as, &pg->nr_pgpaths, &ti->error);
1018 if (r)
1019 goto bad;
1020
1021 r = dm_read_arg(_args + 1, as, &nr_selector_args, &ti->error);
1022 if (r)
1023 goto bad;
1024
1025 nr_args = 1 + nr_selector_args;
1026 for (i = 0; i < pg->nr_pgpaths; i++) {
1027 struct pgpath *pgpath;
1028 struct dm_arg_set path_args;
1029
1030 if (as->argc < nr_args) {
1031 ti->error = "not enough path parameters";
1032 r = -EINVAL;
1033 goto bad;
1034 }
1035
1036 path_args.argc = nr_args;
1037 path_args.argv = as->argv;
1038
1039 pgpath = parse_path(&path_args, &pg->ps, ti);
1040 if (IS_ERR(pgpath)) {
1041 r = PTR_ERR(pgpath);
1042 goto bad;
1043 }
1044
1045 pgpath->pg = pg;
1046 list_add_tail(&pgpath->list, &pg->pgpaths);
1047 dm_consume_args(as, nr_args);
1048 }
1049
1050 return pg;
1051
1052 bad:
1053 free_priority_group(pg, ti);
1054 return ERR_PTR(r);
1055}
1056
1057static int parse_hw_handler(struct dm_arg_set *as, struct multipath *m)
1058{
1059 unsigned int hw_argc;
1060 int ret;
1061 struct dm_target *ti = m->ti;
1062
1063 static const struct dm_arg _args[] = {
1064 {0, 1024, "invalid number of hardware handler args"},
1065 };
1066
1067 if (dm_read_arg_group(_args, as, &hw_argc, &ti->error))
1068 return -EINVAL;
1069
1070 if (!hw_argc)
1071 return 0;
1072
1073 if (m->queue_mode == DM_TYPE_BIO_BASED) {
1074 dm_consume_args(as, hw_argc);
1075 DMERR("bio-based multipath doesn't allow hardware handler args");
1076 return 0;
1077 }
1078
1079 m->hw_handler_name = kstrdup(dm_shift_arg(as), GFP_KERNEL);
1080 if (!m->hw_handler_name)
1081 return -EINVAL;
1082
1083 if (hw_argc > 1) {
1084 char *p;
1085 int i, j, len = 4;
1086
1087 for (i = 0; i <= hw_argc - 2; i++)
1088 len += strlen(as->argv[i]) + 1;
1089 p = m->hw_handler_params = kzalloc(len, GFP_KERNEL);
1090 if (!p) {
1091 ti->error = "memory allocation failed";
1092 ret = -ENOMEM;
1093 goto fail;
1094 }
1095 j = sprintf(p, "%d", hw_argc - 1);
1096 for (i = 0, p += j + 1; i <= hw_argc - 2; i++, p += j + 1)
1097 j = sprintf(p, "%s", as->argv[i]);
1098 }
1099 dm_consume_args(as, hw_argc - 1);
1100
1101 return 0;
1102fail:
1103 kfree(m->hw_handler_name);
1104 m->hw_handler_name = NULL;
1105 return ret;
1106}
1107
1108static int parse_features(struct dm_arg_set *as, struct multipath *m)
1109{
1110 int r;
1111 unsigned int argc;
1112 struct dm_target *ti = m->ti;
1113 const char *arg_name;
1114
1115 static const struct dm_arg _args[] = {
1116 {0, 8, "invalid number of feature args"},
1117 {1, 50, "pg_init_retries must be between 1 and 50"},
1118 {0, 60000, "pg_init_delay_msecs must be between 0 and 60000"},
1119 };
1120
1121 r = dm_read_arg_group(_args, as, &argc, &ti->error);
1122 if (r)
1123 return -EINVAL;
1124
1125 if (!argc)
1126 return 0;
1127
1128 do {
1129 arg_name = dm_shift_arg(as);
1130 argc--;
1131
1132 if (!strcasecmp(arg_name, "queue_if_no_path")) {
1133 r = queue_if_no_path(m, true, false, __func__);
1134 continue;
1135 }
1136
1137 if (!strcasecmp(arg_name, "retain_attached_hw_handler")) {
1138 set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags);
1139 continue;
1140 }
1141
1142 if (!strcasecmp(arg_name, "pg_init_retries") &&
1143 (argc >= 1)) {
1144 r = dm_read_arg(_args + 1, as, &m->pg_init_retries, &ti->error);
1145 argc--;
1146 continue;
1147 }
1148
1149 if (!strcasecmp(arg_name, "pg_init_delay_msecs") &&
1150 (argc >= 1)) {
1151 r = dm_read_arg(_args + 2, as, &m->pg_init_delay_msecs, &ti->error);
1152 argc--;
1153 continue;
1154 }
1155
1156 if (!strcasecmp(arg_name, "queue_mode") &&
1157 (argc >= 1)) {
1158 const char *queue_mode_name = dm_shift_arg(as);
1159
1160 if (!strcasecmp(queue_mode_name, "bio"))
1161 m->queue_mode = DM_TYPE_BIO_BASED;
1162 else if (!strcasecmp(queue_mode_name, "rq") ||
1163 !strcasecmp(queue_mode_name, "mq"))
1164 m->queue_mode = DM_TYPE_REQUEST_BASED;
1165 else {
1166 ti->error = "Unknown 'queue_mode' requested";
1167 r = -EINVAL;
1168 }
1169 argc--;
1170 continue;
1171 }
1172
1173 ti->error = "Unrecognised multipath feature request";
1174 r = -EINVAL;
1175 } while (argc && !r);
1176
1177 return r;
1178}
1179
1180static int multipath_ctr(struct dm_target *ti, unsigned int argc, char **argv)
1181{
1182 /* target arguments */
1183 static const struct dm_arg _args[] = {
1184 {0, 1024, "invalid number of priority groups"},
1185 {0, 1024, "invalid initial priority group number"},
1186 };
1187
1188 int r;
1189 struct multipath *m;
1190 struct dm_arg_set as;
1191 unsigned int pg_count = 0;
1192 unsigned int next_pg_num;
1193 unsigned long flags;
1194
1195 as.argc = argc;
1196 as.argv = argv;
1197
1198 m = alloc_multipath(ti);
1199 if (!m) {
1200 ti->error = "can't allocate multipath";
1201 return -EINVAL;
1202 }
1203
1204 r = parse_features(&as, m);
1205 if (r)
1206 goto bad;
1207
1208 r = alloc_multipath_stage2(ti, m);
1209 if (r)
1210 goto bad;
1211
1212 r = parse_hw_handler(&as, m);
1213 if (r)
1214 goto bad;
1215
1216 r = dm_read_arg(_args, &as, &m->nr_priority_groups, &ti->error);
1217 if (r)
1218 goto bad;
1219
1220 r = dm_read_arg(_args + 1, &as, &next_pg_num, &ti->error);
1221 if (r)
1222 goto bad;
1223
1224 if ((!m->nr_priority_groups && next_pg_num) ||
1225 (m->nr_priority_groups && !next_pg_num)) {
1226 ti->error = "invalid initial priority group";
1227 r = -EINVAL;
1228 goto bad;
1229 }
1230
1231 /* parse the priority groups */
1232 while (as.argc) {
1233 struct priority_group *pg;
1234 unsigned int nr_valid_paths = atomic_read(&m->nr_valid_paths);
1235
1236 pg = parse_priority_group(&as, m);
1237 if (IS_ERR(pg)) {
1238 r = PTR_ERR(pg);
1239 goto bad;
1240 }
1241
1242 nr_valid_paths += pg->nr_pgpaths;
1243 atomic_set(&m->nr_valid_paths, nr_valid_paths);
1244
1245 list_add_tail(&pg->list, &m->priority_groups);
1246 pg_count++;
1247 pg->pg_num = pg_count;
1248 if (!--next_pg_num)
1249 m->next_pg = pg;
1250 }
1251
1252 if (pg_count != m->nr_priority_groups) {
1253 ti->error = "priority group count mismatch";
1254 r = -EINVAL;
1255 goto bad;
1256 }
1257
1258 spin_lock_irqsave(&m->lock, flags);
1259 enable_nopath_timeout(m);
1260 spin_unlock_irqrestore(&m->lock, flags);
1261
1262 ti->num_flush_bios = 1;
1263 ti->num_discard_bios = 1;
1264 ti->num_write_zeroes_bios = 1;
1265 if (m->queue_mode == DM_TYPE_BIO_BASED)
1266 ti->per_io_data_size = multipath_per_bio_data_size();
1267 else
1268 ti->per_io_data_size = sizeof(struct dm_mpath_io);
1269
1270 return 0;
1271
1272 bad:
1273 free_multipath(m);
1274 return r;
1275}
1276
1277static void multipath_wait_for_pg_init_completion(struct multipath *m)
1278{
1279 DEFINE_WAIT(wait);
1280
1281 while (1) {
1282 prepare_to_wait(&m->pg_init_wait, &wait, TASK_UNINTERRUPTIBLE);
1283
1284 if (!atomic_read(&m->pg_init_in_progress))
1285 break;
1286
1287 io_schedule();
1288 }
1289 finish_wait(&m->pg_init_wait, &wait);
1290}
1291
1292static void flush_multipath_work(struct multipath *m)
1293{
1294 if (m->hw_handler_name) {
1295 unsigned long flags;
1296
1297 if (!atomic_read(&m->pg_init_in_progress))
1298 goto skip;
1299
1300 spin_lock_irqsave(&m->lock, flags);
1301 if (atomic_read(&m->pg_init_in_progress) &&
1302 !test_and_set_bit(MPATHF_PG_INIT_DISABLED, &m->flags)) {
1303 spin_unlock_irqrestore(&m->lock, flags);
1304
1305 flush_workqueue(kmpath_handlerd);
1306 multipath_wait_for_pg_init_completion(m);
1307
1308 spin_lock_irqsave(&m->lock, flags);
1309 clear_bit(MPATHF_PG_INIT_DISABLED, &m->flags);
1310 }
1311 spin_unlock_irqrestore(&m->lock, flags);
1312 }
1313skip:
1314 if (m->queue_mode == DM_TYPE_BIO_BASED)
1315 flush_work(&m->process_queued_bios);
1316 flush_work(&m->trigger_event);
1317}
1318
1319static void multipath_dtr(struct dm_target *ti)
1320{
1321 struct multipath *m = ti->private;
1322
1323 disable_nopath_timeout(m);
1324 flush_multipath_work(m);
1325 free_multipath(m);
1326}
1327
1328/*
1329 * Take a path out of use.
1330 */
1331static int fail_path(struct pgpath *pgpath)
1332{
1333 unsigned long flags;
1334 struct multipath *m = pgpath->pg->m;
1335
1336 spin_lock_irqsave(&m->lock, flags);
1337
1338 if (!pgpath->is_active)
1339 goto out;
1340
1341 DMWARN("%s: Failing path %s.",
1342 dm_table_device_name(m->ti->table),
1343 pgpath->path.dev->name);
1344
1345 pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
1346 pgpath->is_active = false;
1347 pgpath->fail_count++;
1348
1349 atomic_dec(&m->nr_valid_paths);
1350
1351 if (pgpath == m->current_pgpath)
1352 m->current_pgpath = NULL;
1353
1354 dm_path_uevent(DM_UEVENT_PATH_FAILED, m->ti,
1355 pgpath->path.dev->name, atomic_read(&m->nr_valid_paths));
1356
1357 queue_work(dm_mpath_wq, &m->trigger_event);
1358
1359 enable_nopath_timeout(m);
1360
1361out:
1362 spin_unlock_irqrestore(&m->lock, flags);
1363
1364 return 0;
1365}
1366
1367/*
1368 * Reinstate a previously-failed path
1369 */
1370static int reinstate_path(struct pgpath *pgpath)
1371{
1372 int r = 0, run_queue = 0;
1373 unsigned long flags;
1374 struct multipath *m = pgpath->pg->m;
1375 unsigned int nr_valid_paths;
1376
1377 spin_lock_irqsave(&m->lock, flags);
1378
1379 if (pgpath->is_active)
1380 goto out;
1381
1382 DMWARN("%s: Reinstating path %s.",
1383 dm_table_device_name(m->ti->table),
1384 pgpath->path.dev->name);
1385
1386 r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
1387 if (r)
1388 goto out;
1389
1390 pgpath->is_active = true;
1391
1392 nr_valid_paths = atomic_inc_return(&m->nr_valid_paths);
1393 if (nr_valid_paths == 1) {
1394 m->current_pgpath = NULL;
1395 run_queue = 1;
1396 } else if (m->hw_handler_name && (m->current_pg == pgpath->pg)) {
1397 if (queue_work(kmpath_handlerd, &pgpath->activate_path.work))
1398 atomic_inc(&m->pg_init_in_progress);
1399 }
1400
1401 dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti,
1402 pgpath->path.dev->name, nr_valid_paths);
1403
1404 schedule_work(&m->trigger_event);
1405
1406out:
1407 spin_unlock_irqrestore(&m->lock, flags);
1408 if (run_queue) {
1409 dm_table_run_md_queue_async(m->ti->table);
1410 process_queued_io_list(m);
1411 }
1412
1413 if (pgpath->is_active)
1414 disable_nopath_timeout(m);
1415
1416 return r;
1417}
1418
1419/*
1420 * Fail or reinstate all paths that match the provided struct dm_dev.
1421 */
1422static int action_dev(struct multipath *m, dev_t dev, action_fn action)
1423{
1424 int r = -EINVAL;
1425 struct pgpath *pgpath;
1426 struct priority_group *pg;
1427
1428 list_for_each_entry(pg, &m->priority_groups, list) {
1429 list_for_each_entry(pgpath, &pg->pgpaths, list) {
1430 if (pgpath->path.dev->bdev->bd_dev == dev)
1431 r = action(pgpath);
1432 }
1433 }
1434
1435 return r;
1436}
1437
1438/*
1439 * Temporarily try to avoid having to use the specified PG
1440 */
1441static void bypass_pg(struct multipath *m, struct priority_group *pg,
1442 bool bypassed)
1443{
1444 unsigned long flags;
1445
1446 spin_lock_irqsave(&m->lock, flags);
1447
1448 pg->bypassed = bypassed;
1449 m->current_pgpath = NULL;
1450 m->current_pg = NULL;
1451
1452 spin_unlock_irqrestore(&m->lock, flags);
1453
1454 schedule_work(&m->trigger_event);
1455}
1456
1457/*
1458 * Switch to using the specified PG from the next I/O that gets mapped
1459 */
1460static int switch_pg_num(struct multipath *m, const char *pgstr)
1461{
1462 struct priority_group *pg;
1463 unsigned int pgnum;
1464 unsigned long flags;
1465 char dummy;
1466
1467 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1468 !m->nr_priority_groups || (pgnum > m->nr_priority_groups)) {
1469 DMWARN("invalid PG number supplied to %s", __func__);
1470 return -EINVAL;
1471 }
1472
1473 spin_lock_irqsave(&m->lock, flags);
1474 list_for_each_entry(pg, &m->priority_groups, list) {
1475 pg->bypassed = false;
1476 if (--pgnum)
1477 continue;
1478
1479 m->current_pgpath = NULL;
1480 m->current_pg = NULL;
1481 m->next_pg = pg;
1482 }
1483 spin_unlock_irqrestore(&m->lock, flags);
1484
1485 schedule_work(&m->trigger_event);
1486 return 0;
1487}
1488
1489/*
1490 * Set/clear bypassed status of a PG.
1491 * PGs are numbered upwards from 1 in the order they were declared.
1492 */
1493static int bypass_pg_num(struct multipath *m, const char *pgstr, bool bypassed)
1494{
1495 struct priority_group *pg;
1496 unsigned int pgnum;
1497 char dummy;
1498
1499 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1500 !m->nr_priority_groups || (pgnum > m->nr_priority_groups)) {
1501 DMWARN("invalid PG number supplied to bypass_pg");
1502 return -EINVAL;
1503 }
1504
1505 list_for_each_entry(pg, &m->priority_groups, list) {
1506 if (!--pgnum)
1507 break;
1508 }
1509
1510 bypass_pg(m, pg, bypassed);
1511 return 0;
1512}
1513
1514/*
1515 * Should we retry pg_init immediately?
1516 */
1517static bool pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath)
1518{
1519 unsigned long flags;
1520 bool limit_reached = false;
1521
1522 spin_lock_irqsave(&m->lock, flags);
1523
1524 if (atomic_read(&m->pg_init_count) <= m->pg_init_retries &&
1525 !test_bit(MPATHF_PG_INIT_DISABLED, &m->flags))
1526 set_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
1527 else
1528 limit_reached = true;
1529
1530 spin_unlock_irqrestore(&m->lock, flags);
1531
1532 return limit_reached;
1533}
1534
1535static void pg_init_done(void *data, int errors)
1536{
1537 struct pgpath *pgpath = data;
1538 struct priority_group *pg = pgpath->pg;
1539 struct multipath *m = pg->m;
1540 unsigned long flags;
1541 bool delay_retry = false;
1542
1543 /* device or driver problems */
1544 switch (errors) {
1545 case SCSI_DH_OK:
1546 break;
1547 case SCSI_DH_NOSYS:
1548 if (!m->hw_handler_name) {
1549 errors = 0;
1550 break;
1551 }
1552 DMERR("Could not failover the device: Handler scsi_dh_%s "
1553 "Error %d.", m->hw_handler_name, errors);
1554 /*
1555 * Fail path for now, so we do not ping pong
1556 */
1557 fail_path(pgpath);
1558 break;
1559 case SCSI_DH_DEV_TEMP_BUSY:
1560 /*
1561 * Probably doing something like FW upgrade on the
1562 * controller so try the other pg.
1563 */
1564 bypass_pg(m, pg, true);
1565 break;
1566 case SCSI_DH_RETRY:
1567 /* Wait before retrying. */
1568 delay_retry = true;
1569 fallthrough;
1570 case SCSI_DH_IMM_RETRY:
1571 case SCSI_DH_RES_TEMP_UNAVAIL:
1572 if (pg_init_limit_reached(m, pgpath))
1573 fail_path(pgpath);
1574 errors = 0;
1575 break;
1576 case SCSI_DH_DEV_OFFLINED:
1577 default:
1578 /*
1579 * We probably do not want to fail the path for a device
1580 * error, but this is what the old dm did. In future
1581 * patches we can do more advanced handling.
1582 */
1583 fail_path(pgpath);
1584 }
1585
1586 spin_lock_irqsave(&m->lock, flags);
1587 if (errors) {
1588 if (pgpath == m->current_pgpath) {
1589 DMERR("Could not failover device. Error %d.", errors);
1590 m->current_pgpath = NULL;
1591 m->current_pg = NULL;
1592 }
1593 } else if (!test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
1594 pg->bypassed = false;
1595
1596 if (atomic_dec_return(&m->pg_init_in_progress) > 0)
1597 /* Activations of other paths are still on going */
1598 goto out;
1599
1600 if (test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags)) {
1601 if (delay_retry)
1602 set_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
1603 else
1604 clear_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
1605
1606 if (__pg_init_all_paths(m))
1607 goto out;
1608 }
1609 clear_bit(MPATHF_QUEUE_IO, &m->flags);
1610
1611 process_queued_io_list(m);
1612
1613 /*
1614 * Wake up any thread waiting to suspend.
1615 */
1616 wake_up(&m->pg_init_wait);
1617
1618out:
1619 spin_unlock_irqrestore(&m->lock, flags);
1620}
1621
1622static void activate_or_offline_path(struct pgpath *pgpath)
1623{
1624 struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
1625
1626 if (pgpath->is_active && !blk_queue_dying(q))
1627 scsi_dh_activate(q, pg_init_done, pgpath);
1628 else
1629 pg_init_done(pgpath, SCSI_DH_DEV_OFFLINED);
1630}
1631
1632static void activate_path_work(struct work_struct *work)
1633{
1634 struct pgpath *pgpath =
1635 container_of(work, struct pgpath, activate_path.work);
1636
1637 activate_or_offline_path(pgpath);
1638}
1639
1640static int multipath_end_io(struct dm_target *ti, struct request *clone,
1641 blk_status_t error, union map_info *map_context)
1642{
1643 struct dm_mpath_io *mpio = get_mpio(map_context);
1644 struct pgpath *pgpath = mpio->pgpath;
1645 int r = DM_ENDIO_DONE;
1646
1647 /*
1648 * We don't queue any clone request inside the multipath target
1649 * during end I/O handling, since those clone requests don't have
1650 * bio clones. If we queue them inside the multipath target,
1651 * we need to make bio clones, that requires memory allocation.
1652 * (See drivers/md/dm-rq.c:end_clone_bio() about why the clone requests
1653 * don't have bio clones.)
1654 * Instead of queueing the clone request here, we queue the original
1655 * request into dm core, which will remake a clone request and
1656 * clone bios for it and resubmit it later.
1657 */
1658 if (error && blk_path_error(error)) {
1659 struct multipath *m = ti->private;
1660
1661 if (error == BLK_STS_RESOURCE)
1662 r = DM_ENDIO_DELAY_REQUEUE;
1663 else
1664 r = DM_ENDIO_REQUEUE;
1665
1666 if (pgpath)
1667 fail_path(pgpath);
1668
1669 if (!atomic_read(&m->nr_valid_paths) &&
1670 !must_push_back_rq(m)) {
1671 if (error == BLK_STS_IOERR)
1672 dm_report_EIO(m);
1673 /* complete with the original error */
1674 r = DM_ENDIO_DONE;
1675 }
1676 }
1677
1678 if (pgpath) {
1679 struct path_selector *ps = &pgpath->pg->ps;
1680
1681 if (ps->type->end_io)
1682 ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes,
1683 clone->io_start_time_ns);
1684 }
1685
1686 return r;
1687}
1688
1689static int multipath_end_io_bio(struct dm_target *ti, struct bio *clone,
1690 blk_status_t *error)
1691{
1692 struct multipath *m = ti->private;
1693 struct dm_mpath_io *mpio = get_mpio_from_bio(clone);
1694 struct pgpath *pgpath = mpio->pgpath;
1695 unsigned long flags;
1696 int r = DM_ENDIO_DONE;
1697
1698 if (!*error || !blk_path_error(*error))
1699 goto done;
1700
1701 if (pgpath)
1702 fail_path(pgpath);
1703
1704 if (!atomic_read(&m->nr_valid_paths)) {
1705 spin_lock_irqsave(&m->lock, flags);
1706 if (!test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
1707 if (__must_push_back(m)) {
1708 r = DM_ENDIO_REQUEUE;
1709 } else {
1710 dm_report_EIO(m);
1711 *error = BLK_STS_IOERR;
1712 }
1713 spin_unlock_irqrestore(&m->lock, flags);
1714 goto done;
1715 }
1716 spin_unlock_irqrestore(&m->lock, flags);
1717 }
1718
1719 multipath_queue_bio(m, clone);
1720 r = DM_ENDIO_INCOMPLETE;
1721done:
1722 if (pgpath) {
1723 struct path_selector *ps = &pgpath->pg->ps;
1724
1725 if (ps->type->end_io)
1726 ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes,
1727 (mpio->start_time_ns ?:
1728 dm_start_time_ns_from_clone(clone)));
1729 }
1730
1731 return r;
1732}
1733
1734/*
1735 * Suspend with flush can't complete until all the I/O is processed
1736 * so if the last path fails we must error any remaining I/O.
1737 * - Note that if the freeze_bdev fails while suspending, the
1738 * queue_if_no_path state is lost - userspace should reset it.
1739 * Otherwise, during noflush suspend, queue_if_no_path will not change.
1740 */
1741static void multipath_presuspend(struct dm_target *ti)
1742{
1743 struct multipath *m = ti->private;
1744
1745 /* FIXME: bio-based shouldn't need to always disable queue_if_no_path */
1746 if (m->queue_mode == DM_TYPE_BIO_BASED || !dm_noflush_suspending(m->ti))
1747 queue_if_no_path(m, false, true, __func__);
1748}
1749
1750static void multipath_postsuspend(struct dm_target *ti)
1751{
1752 struct multipath *m = ti->private;
1753
1754 mutex_lock(&m->work_mutex);
1755 flush_multipath_work(m);
1756 mutex_unlock(&m->work_mutex);
1757}
1758
1759/*
1760 * Restore the queue_if_no_path setting.
1761 */
1762static void multipath_resume(struct dm_target *ti)
1763{
1764 struct multipath *m = ti->private;
1765 unsigned long flags;
1766
1767 spin_lock_irqsave(&m->lock, flags);
1768 if (test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags)) {
1769 set_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
1770 clear_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
1771 }
1772
1773 DMDEBUG("%s: %s finished; QIFNP = %d; SQIFNP = %d",
1774 dm_table_device_name(m->ti->table), __func__,
1775 test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags),
1776 test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags));
1777
1778 spin_unlock_irqrestore(&m->lock, flags);
1779}
1780
1781/*
1782 * Info output has the following format:
1783 * num_multipath_feature_args [multipath_feature_args]*
1784 * num_handler_status_args [handler_status_args]*
1785 * num_groups init_group_number
1786 * [A|D|E num_ps_status_args [ps_status_args]*
1787 * num_paths num_selector_args
1788 * [path_dev A|F fail_count [selector_args]* ]+ ]+
1789 *
1790 * Table output has the following format (identical to the constructor string):
1791 * num_feature_args [features_args]*
1792 * num_handler_args hw_handler [hw_handler_args]*
1793 * num_groups init_group_number
1794 * [priority selector-name num_ps_args [ps_args]*
1795 * num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
1796 */
1797static void multipath_status(struct dm_target *ti, status_type_t type,
1798 unsigned int status_flags, char *result, unsigned int maxlen)
1799{
1800 int sz = 0, pg_counter, pgpath_counter;
1801 unsigned long flags;
1802 struct multipath *m = ti->private;
1803 struct priority_group *pg;
1804 struct pgpath *p;
1805 unsigned int pg_num;
1806 char state;
1807
1808 spin_lock_irqsave(&m->lock, flags);
1809
1810 /* Features */
1811 if (type == STATUSTYPE_INFO)
1812 DMEMIT("2 %u %u ", test_bit(MPATHF_QUEUE_IO, &m->flags),
1813 atomic_read(&m->pg_init_count));
1814 else {
1815 DMEMIT("%u ", test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) +
1816 (m->pg_init_retries > 0) * 2 +
1817 (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT) * 2 +
1818 test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags) +
1819 (m->queue_mode != DM_TYPE_REQUEST_BASED) * 2);
1820
1821 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
1822 DMEMIT("queue_if_no_path ");
1823 if (m->pg_init_retries)
1824 DMEMIT("pg_init_retries %u ", m->pg_init_retries);
1825 if (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT)
1826 DMEMIT("pg_init_delay_msecs %u ", m->pg_init_delay_msecs);
1827 if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags))
1828 DMEMIT("retain_attached_hw_handler ");
1829 if (m->queue_mode != DM_TYPE_REQUEST_BASED) {
1830 switch (m->queue_mode) {
1831 case DM_TYPE_BIO_BASED:
1832 DMEMIT("queue_mode bio ");
1833 break;
1834 default:
1835 WARN_ON_ONCE(true);
1836 break;
1837 }
1838 }
1839 }
1840
1841 if (!m->hw_handler_name || type == STATUSTYPE_INFO)
1842 DMEMIT("0 ");
1843 else
1844 DMEMIT("1 %s ", m->hw_handler_name);
1845
1846 DMEMIT("%u ", m->nr_priority_groups);
1847
1848 if (m->next_pg)
1849 pg_num = m->next_pg->pg_num;
1850 else if (m->current_pg)
1851 pg_num = m->current_pg->pg_num;
1852 else
1853 pg_num = (m->nr_priority_groups ? 1 : 0);
1854
1855 DMEMIT("%u ", pg_num);
1856
1857 switch (type) {
1858 case STATUSTYPE_INFO:
1859 list_for_each_entry(pg, &m->priority_groups, list) {
1860 if (pg->bypassed)
1861 state = 'D'; /* Disabled */
1862 else if (pg == m->current_pg)
1863 state = 'A'; /* Currently Active */
1864 else
1865 state = 'E'; /* Enabled */
1866
1867 DMEMIT("%c ", state);
1868
1869 if (pg->ps.type->status)
1870 sz += pg->ps.type->status(&pg->ps, NULL, type,
1871 result + sz,
1872 maxlen - sz);
1873 else
1874 DMEMIT("0 ");
1875
1876 DMEMIT("%u %u ", pg->nr_pgpaths,
1877 pg->ps.type->info_args);
1878
1879 list_for_each_entry(p, &pg->pgpaths, list) {
1880 DMEMIT("%s %s %u ", p->path.dev->name,
1881 p->is_active ? "A" : "F",
1882 p->fail_count);
1883 if (pg->ps.type->status)
1884 sz += pg->ps.type->status(&pg->ps,
1885 &p->path, type, result + sz,
1886 maxlen - sz);
1887 }
1888 }
1889 break;
1890
1891 case STATUSTYPE_TABLE:
1892 list_for_each_entry(pg, &m->priority_groups, list) {
1893 DMEMIT("%s ", pg->ps.type->name);
1894
1895 if (pg->ps.type->status)
1896 sz += pg->ps.type->status(&pg->ps, NULL, type,
1897 result + sz,
1898 maxlen - sz);
1899 else
1900 DMEMIT("0 ");
1901
1902 DMEMIT("%u %u ", pg->nr_pgpaths,
1903 pg->ps.type->table_args);
1904
1905 list_for_each_entry(p, &pg->pgpaths, list) {
1906 DMEMIT("%s ", p->path.dev->name);
1907 if (pg->ps.type->status)
1908 sz += pg->ps.type->status(&pg->ps,
1909 &p->path, type, result + sz,
1910 maxlen - sz);
1911 }
1912 }
1913 break;
1914
1915 case STATUSTYPE_IMA:
1916 sz = 0; /*reset the result pointer*/
1917
1918 DMEMIT_TARGET_NAME_VERSION(ti->type);
1919 DMEMIT(",nr_priority_groups=%u", m->nr_priority_groups);
1920
1921 pg_counter = 0;
1922 list_for_each_entry(pg, &m->priority_groups, list) {
1923 if (pg->bypassed)
1924 state = 'D'; /* Disabled */
1925 else if (pg == m->current_pg)
1926 state = 'A'; /* Currently Active */
1927 else
1928 state = 'E'; /* Enabled */
1929 DMEMIT(",pg_state_%d=%c", pg_counter, state);
1930 DMEMIT(",nr_pgpaths_%d=%u", pg_counter, pg->nr_pgpaths);
1931 DMEMIT(",path_selector_name_%d=%s", pg_counter, pg->ps.type->name);
1932
1933 pgpath_counter = 0;
1934 list_for_each_entry(p, &pg->pgpaths, list) {
1935 DMEMIT(",path_name_%d_%d=%s,is_active_%d_%d=%c,fail_count_%d_%d=%u",
1936 pg_counter, pgpath_counter, p->path.dev->name,
1937 pg_counter, pgpath_counter, p->is_active ? 'A' : 'F',
1938 pg_counter, pgpath_counter, p->fail_count);
1939 if (pg->ps.type->status) {
1940 DMEMIT(",path_selector_status_%d_%d=",
1941 pg_counter, pgpath_counter);
1942 sz += pg->ps.type->status(&pg->ps, &p->path,
1943 type, result + sz,
1944 maxlen - sz);
1945 }
1946 pgpath_counter++;
1947 }
1948 pg_counter++;
1949 }
1950 DMEMIT(";");
1951 break;
1952 }
1953
1954 spin_unlock_irqrestore(&m->lock, flags);
1955}
1956
1957static int multipath_message(struct dm_target *ti, unsigned int argc, char **argv,
1958 char *result, unsigned int maxlen)
1959{
1960 int r = -EINVAL;
1961 dev_t dev;
1962 struct multipath *m = ti->private;
1963 action_fn action;
1964 unsigned long flags;
1965
1966 mutex_lock(&m->work_mutex);
1967
1968 if (dm_suspended(ti)) {
1969 r = -EBUSY;
1970 goto out;
1971 }
1972
1973 if (argc == 1) {
1974 if (!strcasecmp(argv[0], "queue_if_no_path")) {
1975 r = queue_if_no_path(m, true, false, __func__);
1976 spin_lock_irqsave(&m->lock, flags);
1977 enable_nopath_timeout(m);
1978 spin_unlock_irqrestore(&m->lock, flags);
1979 goto out;
1980 } else if (!strcasecmp(argv[0], "fail_if_no_path")) {
1981 r = queue_if_no_path(m, false, false, __func__);
1982 disable_nopath_timeout(m);
1983 goto out;
1984 }
1985 }
1986
1987 if (argc != 2) {
1988 DMWARN("Invalid multipath message arguments. Expected 2 arguments, got %d.", argc);
1989 goto out;
1990 }
1991
1992 if (!strcasecmp(argv[0], "disable_group")) {
1993 r = bypass_pg_num(m, argv[1], true);
1994 goto out;
1995 } else if (!strcasecmp(argv[0], "enable_group")) {
1996 r = bypass_pg_num(m, argv[1], false);
1997 goto out;
1998 } else if (!strcasecmp(argv[0], "switch_group")) {
1999 r = switch_pg_num(m, argv[1]);
2000 goto out;
2001 } else if (!strcasecmp(argv[0], "reinstate_path"))
2002 action = reinstate_path;
2003 else if (!strcasecmp(argv[0], "fail_path"))
2004 action = fail_path;
2005 else {
2006 DMWARN("Unrecognised multipath message received: %s", argv[0]);
2007 goto out;
2008 }
2009
2010 r = dm_devt_from_path(argv[1], &dev);
2011 if (r) {
2012 DMWARN("message: error getting device %s",
2013 argv[1]);
2014 goto out;
2015 }
2016
2017 r = action_dev(m, dev, action);
2018
2019out:
2020 mutex_unlock(&m->work_mutex);
2021 return r;
2022}
2023
2024static int multipath_prepare_ioctl(struct dm_target *ti,
2025 struct block_device **bdev)
2026{
2027 struct multipath *m = ti->private;
2028 struct pgpath *pgpath;
2029 unsigned long flags;
2030 int r;
2031
2032 pgpath = READ_ONCE(m->current_pgpath);
2033 if (!pgpath || !mpath_double_check_test_bit(MPATHF_QUEUE_IO, m))
2034 pgpath = choose_pgpath(m, 0);
2035
2036 if (pgpath) {
2037 if (!mpath_double_check_test_bit(MPATHF_QUEUE_IO, m)) {
2038 *bdev = pgpath->path.dev->bdev;
2039 r = 0;
2040 } else {
2041 /* pg_init has not started or completed */
2042 r = -ENOTCONN;
2043 }
2044 } else {
2045 /* No path is available */
2046 r = -EIO;
2047 spin_lock_irqsave(&m->lock, flags);
2048 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
2049 r = -ENOTCONN;
2050 spin_unlock_irqrestore(&m->lock, flags);
2051 }
2052
2053 if (r == -ENOTCONN) {
2054 if (!READ_ONCE(m->current_pg)) {
2055 /* Path status changed, redo selection */
2056 (void) choose_pgpath(m, 0);
2057 }
2058 spin_lock_irqsave(&m->lock, flags);
2059 if (test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
2060 (void) __pg_init_all_paths(m);
2061 spin_unlock_irqrestore(&m->lock, flags);
2062 dm_table_run_md_queue_async(m->ti->table);
2063 process_queued_io_list(m);
2064 }
2065
2066 /*
2067 * Only pass ioctls through if the device sizes match exactly.
2068 */
2069 if (!r && ti->len != bdev_nr_sectors((*bdev)))
2070 return 1;
2071 return r;
2072}
2073
2074static int multipath_iterate_devices(struct dm_target *ti,
2075 iterate_devices_callout_fn fn, void *data)
2076{
2077 struct multipath *m = ti->private;
2078 struct priority_group *pg;
2079 struct pgpath *p;
2080 int ret = 0;
2081
2082 list_for_each_entry(pg, &m->priority_groups, list) {
2083 list_for_each_entry(p, &pg->pgpaths, list) {
2084 ret = fn(ti, p->path.dev, ti->begin, ti->len, data);
2085 if (ret)
2086 goto out;
2087 }
2088 }
2089
2090out:
2091 return ret;
2092}
2093
2094static int pgpath_busy(struct pgpath *pgpath)
2095{
2096 struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
2097
2098 return blk_lld_busy(q);
2099}
2100
2101/*
2102 * We return "busy", only when we can map I/Os but underlying devices
2103 * are busy (so even if we map I/Os now, the I/Os will wait on
2104 * the underlying queue).
2105 * In other words, if we want to kill I/Os or queue them inside us
2106 * due to map unavailability, we don't return "busy". Otherwise,
2107 * dm core won't give us the I/Os and we can't do what we want.
2108 */
2109static int multipath_busy(struct dm_target *ti)
2110{
2111 bool busy = false, has_active = false;
2112 struct multipath *m = ti->private;
2113 struct priority_group *pg, *next_pg;
2114 struct pgpath *pgpath;
2115
2116 /* pg_init in progress */
2117 if (atomic_read(&m->pg_init_in_progress))
2118 return true;
2119
2120 /* no paths available, for blk-mq: rely on IO mapping to delay requeue */
2121 if (!atomic_read(&m->nr_valid_paths)) {
2122 unsigned long flags;
2123
2124 spin_lock_irqsave(&m->lock, flags);
2125 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
2126 spin_unlock_irqrestore(&m->lock, flags);
2127 return (m->queue_mode != DM_TYPE_REQUEST_BASED);
2128 }
2129 spin_unlock_irqrestore(&m->lock, flags);
2130 }
2131
2132 /* Guess which priority_group will be used at next mapping time */
2133 pg = READ_ONCE(m->current_pg);
2134 next_pg = READ_ONCE(m->next_pg);
2135 if (unlikely(!READ_ONCE(m->current_pgpath) && next_pg))
2136 pg = next_pg;
2137
2138 if (!pg) {
2139 /*
2140 * We don't know which pg will be used at next mapping time.
2141 * We don't call choose_pgpath() here to avoid to trigger
2142 * pg_init just by busy checking.
2143 * So we don't know whether underlying devices we will be using
2144 * at next mapping time are busy or not. Just try mapping.
2145 */
2146 return busy;
2147 }
2148
2149 /*
2150 * If there is one non-busy active path at least, the path selector
2151 * will be able to select it. So we consider such a pg as not busy.
2152 */
2153 busy = true;
2154 list_for_each_entry(pgpath, &pg->pgpaths, list) {
2155 if (pgpath->is_active) {
2156 has_active = true;
2157 if (!pgpath_busy(pgpath)) {
2158 busy = false;
2159 break;
2160 }
2161 }
2162 }
2163
2164 if (!has_active) {
2165 /*
2166 * No active path in this pg, so this pg won't be used and
2167 * the current_pg will be changed at next mapping time.
2168 * We need to try mapping to determine it.
2169 */
2170 busy = false;
2171 }
2172
2173 return busy;
2174}
2175
2176/*
2177 *---------------------------------------------------------------
2178 * Module setup
2179 *---------------------------------------------------------------
2180 */
2181static struct target_type multipath_target = {
2182 .name = "multipath",
2183 .version = {1, 14, 0},
2184 .features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE |
2185 DM_TARGET_PASSES_INTEGRITY,
2186 .module = THIS_MODULE,
2187 .ctr = multipath_ctr,
2188 .dtr = multipath_dtr,
2189 .clone_and_map_rq = multipath_clone_and_map,
2190 .release_clone_rq = multipath_release_clone,
2191 .rq_end_io = multipath_end_io,
2192 .map = multipath_map_bio,
2193 .end_io = multipath_end_io_bio,
2194 .presuspend = multipath_presuspend,
2195 .postsuspend = multipath_postsuspend,
2196 .resume = multipath_resume,
2197 .status = multipath_status,
2198 .message = multipath_message,
2199 .prepare_ioctl = multipath_prepare_ioctl,
2200 .iterate_devices = multipath_iterate_devices,
2201 .busy = multipath_busy,
2202};
2203
2204static int __init dm_multipath_init(void)
2205{
2206 int r = -ENOMEM;
2207
2208 kmultipathd = alloc_workqueue("kmpathd", WQ_MEM_RECLAIM, 0);
2209 if (!kmultipathd) {
2210 DMERR("failed to create workqueue kmpathd");
2211 goto bad_alloc_kmultipathd;
2212 }
2213
2214 /*
2215 * A separate workqueue is used to handle the device handlers
2216 * to avoid overloading existing workqueue. Overloading the
2217 * old workqueue would also create a bottleneck in the
2218 * path of the storage hardware device activation.
2219 */
2220 kmpath_handlerd = alloc_ordered_workqueue("kmpath_handlerd",
2221 WQ_MEM_RECLAIM);
2222 if (!kmpath_handlerd) {
2223 DMERR("failed to create workqueue kmpath_handlerd");
2224 goto bad_alloc_kmpath_handlerd;
2225 }
2226
2227 dm_mpath_wq = alloc_workqueue("dm_mpath_wq", 0, 0);
2228 if (!dm_mpath_wq) {
2229 DMERR("failed to create workqueue dm_mpath_wq");
2230 goto bad_alloc_dm_mpath_wq;
2231 }
2232
2233 r = dm_register_target(&multipath_target);
2234 if (r < 0)
2235 goto bad_register_target;
2236
2237 return 0;
2238
2239bad_register_target:
2240 destroy_workqueue(dm_mpath_wq);
2241bad_alloc_dm_mpath_wq:
2242 destroy_workqueue(kmpath_handlerd);
2243bad_alloc_kmpath_handlerd:
2244 destroy_workqueue(kmultipathd);
2245bad_alloc_kmultipathd:
2246 return r;
2247}
2248
2249static void __exit dm_multipath_exit(void)
2250{
2251 destroy_workqueue(dm_mpath_wq);
2252 destroy_workqueue(kmpath_handlerd);
2253 destroy_workqueue(kmultipathd);
2254
2255 dm_unregister_target(&multipath_target);
2256}
2257
2258module_init(dm_multipath_init);
2259module_exit(dm_multipath_exit);
2260
2261module_param_named(queue_if_no_path_timeout_secs, queue_if_no_path_timeout_secs, ulong, 0644);
2262MODULE_PARM_DESC(queue_if_no_path_timeout_secs, "No available paths queue IO timeout in seconds");
2263
2264MODULE_DESCRIPTION(DM_NAME " multipath target");
2265MODULE_AUTHOR("Sistina Software <dm-devel@lists.linux.dev>");
2266MODULE_LICENSE("GPL");
1/*
2 * Copyright (C) 2003 Sistina Software Limited.
3 * Copyright (C) 2004-2005 Red Hat, Inc. All rights reserved.
4 *
5 * This file is released under the GPL.
6 */
7
8#include <linux/device-mapper.h>
9
10#include "dm-path-selector.h"
11#include "dm-uevent.h"
12
13#include <linux/ctype.h>
14#include <linux/init.h>
15#include <linux/mempool.h>
16#include <linux/module.h>
17#include <linux/pagemap.h>
18#include <linux/slab.h>
19#include <linux/time.h>
20#include <linux/workqueue.h>
21#include <linux/delay.h>
22#include <scsi/scsi_dh.h>
23#include <linux/atomic.h>
24
25#define DM_MSG_PREFIX "multipath"
26#define DM_PG_INIT_DELAY_MSECS 2000
27#define DM_PG_INIT_DELAY_DEFAULT ((unsigned) -1)
28
29/* Path properties */
30struct pgpath {
31 struct list_head list;
32
33 struct priority_group *pg; /* Owning PG */
34 unsigned is_active; /* Path status */
35 unsigned fail_count; /* Cumulative failure count */
36
37 struct dm_path path;
38 struct delayed_work activate_path;
39};
40
41#define path_to_pgpath(__pgp) container_of((__pgp), struct pgpath, path)
42
43/*
44 * Paths are grouped into Priority Groups and numbered from 1 upwards.
45 * Each has a path selector which controls which path gets used.
46 */
47struct priority_group {
48 struct list_head list;
49
50 struct multipath *m; /* Owning multipath instance */
51 struct path_selector ps;
52
53 unsigned pg_num; /* Reference number */
54 unsigned bypassed; /* Temporarily bypass this PG? */
55
56 unsigned nr_pgpaths; /* Number of paths in PG */
57 struct list_head pgpaths;
58};
59
60/* Multipath context */
61struct multipath {
62 struct list_head list;
63 struct dm_target *ti;
64
65 const char *hw_handler_name;
66 char *hw_handler_params;
67
68 spinlock_t lock;
69
70 unsigned nr_priority_groups;
71 struct list_head priority_groups;
72
73 wait_queue_head_t pg_init_wait; /* Wait for pg_init completion */
74
75 unsigned pg_init_required; /* pg_init needs calling? */
76 unsigned pg_init_in_progress; /* Only one pg_init allowed at once */
77 unsigned pg_init_delay_retry; /* Delay pg_init retry? */
78
79 unsigned nr_valid_paths; /* Total number of usable paths */
80 struct pgpath *current_pgpath;
81 struct priority_group *current_pg;
82 struct priority_group *next_pg; /* Switch to this PG if set */
83 unsigned repeat_count; /* I/Os left before calling PS again */
84
85 unsigned queue_io:1; /* Must we queue all I/O? */
86 unsigned queue_if_no_path:1; /* Queue I/O if last path fails? */
87 unsigned saved_queue_if_no_path:1; /* Saved state during suspension */
88
89 unsigned pg_init_retries; /* Number of times to retry pg_init */
90 unsigned pg_init_count; /* Number of times pg_init called */
91 unsigned pg_init_delay_msecs; /* Number of msecs before pg_init retry */
92
93 unsigned queue_size;
94 struct work_struct process_queued_ios;
95 struct list_head queued_ios;
96
97 struct work_struct trigger_event;
98
99 /*
100 * We must use a mempool of dm_mpath_io structs so that we
101 * can resubmit bios on error.
102 */
103 mempool_t *mpio_pool;
104
105 struct mutex work_mutex;
106};
107
108/*
109 * Context information attached to each bio we process.
110 */
111struct dm_mpath_io {
112 struct pgpath *pgpath;
113 size_t nr_bytes;
114};
115
116typedef int (*action_fn) (struct pgpath *pgpath);
117
118#define MIN_IOS 256 /* Mempool size */
119
120static struct kmem_cache *_mpio_cache;
121
122static struct workqueue_struct *kmultipathd, *kmpath_handlerd;
123static void process_queued_ios(struct work_struct *work);
124static void trigger_event(struct work_struct *work);
125static void activate_path(struct work_struct *work);
126
127
128/*-----------------------------------------------
129 * Allocation routines
130 *-----------------------------------------------*/
131
132static struct pgpath *alloc_pgpath(void)
133{
134 struct pgpath *pgpath = kzalloc(sizeof(*pgpath), GFP_KERNEL);
135
136 if (pgpath) {
137 pgpath->is_active = 1;
138 INIT_DELAYED_WORK(&pgpath->activate_path, activate_path);
139 }
140
141 return pgpath;
142}
143
144static void free_pgpath(struct pgpath *pgpath)
145{
146 kfree(pgpath);
147}
148
149static struct priority_group *alloc_priority_group(void)
150{
151 struct priority_group *pg;
152
153 pg = kzalloc(sizeof(*pg), GFP_KERNEL);
154
155 if (pg)
156 INIT_LIST_HEAD(&pg->pgpaths);
157
158 return pg;
159}
160
161static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti)
162{
163 struct pgpath *pgpath, *tmp;
164 struct multipath *m = ti->private;
165
166 list_for_each_entry_safe(pgpath, tmp, pgpaths, list) {
167 list_del(&pgpath->list);
168 if (m->hw_handler_name)
169 scsi_dh_detach(bdev_get_queue(pgpath->path.dev->bdev));
170 dm_put_device(ti, pgpath->path.dev);
171 free_pgpath(pgpath);
172 }
173}
174
175static void free_priority_group(struct priority_group *pg,
176 struct dm_target *ti)
177{
178 struct path_selector *ps = &pg->ps;
179
180 if (ps->type) {
181 ps->type->destroy(ps);
182 dm_put_path_selector(ps->type);
183 }
184
185 free_pgpaths(&pg->pgpaths, ti);
186 kfree(pg);
187}
188
189static struct multipath *alloc_multipath(struct dm_target *ti)
190{
191 struct multipath *m;
192
193 m = kzalloc(sizeof(*m), GFP_KERNEL);
194 if (m) {
195 INIT_LIST_HEAD(&m->priority_groups);
196 INIT_LIST_HEAD(&m->queued_ios);
197 spin_lock_init(&m->lock);
198 m->queue_io = 1;
199 m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT;
200 INIT_WORK(&m->process_queued_ios, process_queued_ios);
201 INIT_WORK(&m->trigger_event, trigger_event);
202 init_waitqueue_head(&m->pg_init_wait);
203 mutex_init(&m->work_mutex);
204 m->mpio_pool = mempool_create_slab_pool(MIN_IOS, _mpio_cache);
205 if (!m->mpio_pool) {
206 kfree(m);
207 return NULL;
208 }
209 m->ti = ti;
210 ti->private = m;
211 }
212
213 return m;
214}
215
216static void free_multipath(struct multipath *m)
217{
218 struct priority_group *pg, *tmp;
219
220 list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) {
221 list_del(&pg->list);
222 free_priority_group(pg, m->ti);
223 }
224
225 kfree(m->hw_handler_name);
226 kfree(m->hw_handler_params);
227 mempool_destroy(m->mpio_pool);
228 kfree(m);
229}
230
231static int set_mapinfo(struct multipath *m, union map_info *info)
232{
233 struct dm_mpath_io *mpio;
234
235 mpio = mempool_alloc(m->mpio_pool, GFP_ATOMIC);
236 if (!mpio)
237 return -ENOMEM;
238
239 memset(mpio, 0, sizeof(*mpio));
240 info->ptr = mpio;
241
242 return 0;
243}
244
245static void clear_mapinfo(struct multipath *m, union map_info *info)
246{
247 struct dm_mpath_io *mpio = info->ptr;
248
249 info->ptr = NULL;
250 mempool_free(mpio, m->mpio_pool);
251}
252
253/*-----------------------------------------------
254 * Path selection
255 *-----------------------------------------------*/
256
257static void __pg_init_all_paths(struct multipath *m)
258{
259 struct pgpath *pgpath;
260 unsigned long pg_init_delay = 0;
261
262 m->pg_init_count++;
263 m->pg_init_required = 0;
264 if (m->pg_init_delay_retry)
265 pg_init_delay = msecs_to_jiffies(m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT ?
266 m->pg_init_delay_msecs : DM_PG_INIT_DELAY_MSECS);
267 list_for_each_entry(pgpath, &m->current_pg->pgpaths, list) {
268 /* Skip failed paths */
269 if (!pgpath->is_active)
270 continue;
271 if (queue_delayed_work(kmpath_handlerd, &pgpath->activate_path,
272 pg_init_delay))
273 m->pg_init_in_progress++;
274 }
275}
276
277static void __switch_pg(struct multipath *m, struct pgpath *pgpath)
278{
279 m->current_pg = pgpath->pg;
280
281 /* Must we initialise the PG first, and queue I/O till it's ready? */
282 if (m->hw_handler_name) {
283 m->pg_init_required = 1;
284 m->queue_io = 1;
285 } else {
286 m->pg_init_required = 0;
287 m->queue_io = 0;
288 }
289
290 m->pg_init_count = 0;
291}
292
293static int __choose_path_in_pg(struct multipath *m, struct priority_group *pg,
294 size_t nr_bytes)
295{
296 struct dm_path *path;
297
298 path = pg->ps.type->select_path(&pg->ps, &m->repeat_count, nr_bytes);
299 if (!path)
300 return -ENXIO;
301
302 m->current_pgpath = path_to_pgpath(path);
303
304 if (m->current_pg != pg)
305 __switch_pg(m, m->current_pgpath);
306
307 return 0;
308}
309
310static void __choose_pgpath(struct multipath *m, size_t nr_bytes)
311{
312 struct priority_group *pg;
313 unsigned bypassed = 1;
314
315 if (!m->nr_valid_paths)
316 goto failed;
317
318 /* Were we instructed to switch PG? */
319 if (m->next_pg) {
320 pg = m->next_pg;
321 m->next_pg = NULL;
322 if (!__choose_path_in_pg(m, pg, nr_bytes))
323 return;
324 }
325
326 /* Don't change PG until it has no remaining paths */
327 if (m->current_pg && !__choose_path_in_pg(m, m->current_pg, nr_bytes))
328 return;
329
330 /*
331 * Loop through priority groups until we find a valid path.
332 * First time we skip PGs marked 'bypassed'.
333 * Second time we only try the ones we skipped, but set
334 * pg_init_delay_retry so we do not hammer controllers.
335 */
336 do {
337 list_for_each_entry(pg, &m->priority_groups, list) {
338 if (pg->bypassed == bypassed)
339 continue;
340 if (!__choose_path_in_pg(m, pg, nr_bytes)) {
341 if (!bypassed)
342 m->pg_init_delay_retry = 1;
343 return;
344 }
345 }
346 } while (bypassed--);
347
348failed:
349 m->current_pgpath = NULL;
350 m->current_pg = NULL;
351}
352
353/*
354 * Check whether bios must be queued in the device-mapper core rather
355 * than here in the target.
356 *
357 * m->lock must be held on entry.
358 *
359 * If m->queue_if_no_path and m->saved_queue_if_no_path hold the
360 * same value then we are not between multipath_presuspend()
361 * and multipath_resume() calls and we have no need to check
362 * for the DMF_NOFLUSH_SUSPENDING flag.
363 */
364static int __must_push_back(struct multipath *m)
365{
366 return (m->queue_if_no_path != m->saved_queue_if_no_path &&
367 dm_noflush_suspending(m->ti));
368}
369
370static int map_io(struct multipath *m, struct request *clone,
371 union map_info *map_context, unsigned was_queued)
372{
373 int r = DM_MAPIO_REMAPPED;
374 size_t nr_bytes = blk_rq_bytes(clone);
375 unsigned long flags;
376 struct pgpath *pgpath;
377 struct block_device *bdev;
378 struct dm_mpath_io *mpio = map_context->ptr;
379
380 spin_lock_irqsave(&m->lock, flags);
381
382 /* Do we need to select a new pgpath? */
383 if (!m->current_pgpath ||
384 (!m->queue_io && (m->repeat_count && --m->repeat_count == 0)))
385 __choose_pgpath(m, nr_bytes);
386
387 pgpath = m->current_pgpath;
388
389 if (was_queued)
390 m->queue_size--;
391
392 if ((pgpath && m->queue_io) ||
393 (!pgpath && m->queue_if_no_path)) {
394 /* Queue for the daemon to resubmit */
395 list_add_tail(&clone->queuelist, &m->queued_ios);
396 m->queue_size++;
397 if ((m->pg_init_required && !m->pg_init_in_progress) ||
398 !m->queue_io)
399 queue_work(kmultipathd, &m->process_queued_ios);
400 pgpath = NULL;
401 r = DM_MAPIO_SUBMITTED;
402 } else if (pgpath) {
403 bdev = pgpath->path.dev->bdev;
404 clone->q = bdev_get_queue(bdev);
405 clone->rq_disk = bdev->bd_disk;
406 } else if (__must_push_back(m))
407 r = DM_MAPIO_REQUEUE;
408 else
409 r = -EIO; /* Failed */
410
411 mpio->pgpath = pgpath;
412 mpio->nr_bytes = nr_bytes;
413
414 if (r == DM_MAPIO_REMAPPED && pgpath->pg->ps.type->start_io)
415 pgpath->pg->ps.type->start_io(&pgpath->pg->ps, &pgpath->path,
416 nr_bytes);
417
418 spin_unlock_irqrestore(&m->lock, flags);
419
420 return r;
421}
422
423/*
424 * If we run out of usable paths, should we queue I/O or error it?
425 */
426static int queue_if_no_path(struct multipath *m, unsigned queue_if_no_path,
427 unsigned save_old_value)
428{
429 unsigned long flags;
430
431 spin_lock_irqsave(&m->lock, flags);
432
433 if (save_old_value)
434 m->saved_queue_if_no_path = m->queue_if_no_path;
435 else
436 m->saved_queue_if_no_path = queue_if_no_path;
437 m->queue_if_no_path = queue_if_no_path;
438 if (!m->queue_if_no_path && m->queue_size)
439 queue_work(kmultipathd, &m->process_queued_ios);
440
441 spin_unlock_irqrestore(&m->lock, flags);
442
443 return 0;
444}
445
446/*-----------------------------------------------------------------
447 * The multipath daemon is responsible for resubmitting queued ios.
448 *---------------------------------------------------------------*/
449
450static void dispatch_queued_ios(struct multipath *m)
451{
452 int r;
453 unsigned long flags;
454 union map_info *info;
455 struct request *clone, *n;
456 LIST_HEAD(cl);
457
458 spin_lock_irqsave(&m->lock, flags);
459 list_splice_init(&m->queued_ios, &cl);
460 spin_unlock_irqrestore(&m->lock, flags);
461
462 list_for_each_entry_safe(clone, n, &cl, queuelist) {
463 list_del_init(&clone->queuelist);
464
465 info = dm_get_rq_mapinfo(clone);
466
467 r = map_io(m, clone, info, 1);
468 if (r < 0) {
469 clear_mapinfo(m, info);
470 dm_kill_unmapped_request(clone, r);
471 } else if (r == DM_MAPIO_REMAPPED)
472 dm_dispatch_request(clone);
473 else if (r == DM_MAPIO_REQUEUE) {
474 clear_mapinfo(m, info);
475 dm_requeue_unmapped_request(clone);
476 }
477 }
478}
479
480static void process_queued_ios(struct work_struct *work)
481{
482 struct multipath *m =
483 container_of(work, struct multipath, process_queued_ios);
484 struct pgpath *pgpath = NULL;
485 unsigned must_queue = 1;
486 unsigned long flags;
487
488 spin_lock_irqsave(&m->lock, flags);
489
490 if (!m->current_pgpath)
491 __choose_pgpath(m, 0);
492
493 pgpath = m->current_pgpath;
494
495 if ((pgpath && !m->queue_io) ||
496 (!pgpath && !m->queue_if_no_path))
497 must_queue = 0;
498
499 if (m->pg_init_required && !m->pg_init_in_progress && pgpath)
500 __pg_init_all_paths(m);
501
502 spin_unlock_irqrestore(&m->lock, flags);
503 if (!must_queue)
504 dispatch_queued_ios(m);
505}
506
507/*
508 * An event is triggered whenever a path is taken out of use.
509 * Includes path failure and PG bypass.
510 */
511static void trigger_event(struct work_struct *work)
512{
513 struct multipath *m =
514 container_of(work, struct multipath, trigger_event);
515
516 dm_table_event(m->ti->table);
517}
518
519/*-----------------------------------------------------------------
520 * Constructor/argument parsing:
521 * <#multipath feature args> [<arg>]*
522 * <#hw_handler args> [hw_handler [<arg>]*]
523 * <#priority groups>
524 * <initial priority group>
525 * [<selector> <#selector args> [<arg>]*
526 * <#paths> <#per-path selector args>
527 * [<path> [<arg>]* ]+ ]+
528 *---------------------------------------------------------------*/
529static int parse_path_selector(struct dm_arg_set *as, struct priority_group *pg,
530 struct dm_target *ti)
531{
532 int r;
533 struct path_selector_type *pst;
534 unsigned ps_argc;
535
536 static struct dm_arg _args[] = {
537 {0, 1024, "invalid number of path selector args"},
538 };
539
540 pst = dm_get_path_selector(dm_shift_arg(as));
541 if (!pst) {
542 ti->error = "unknown path selector type";
543 return -EINVAL;
544 }
545
546 r = dm_read_arg_group(_args, as, &ps_argc, &ti->error);
547 if (r) {
548 dm_put_path_selector(pst);
549 return -EINVAL;
550 }
551
552 r = pst->create(&pg->ps, ps_argc, as->argv);
553 if (r) {
554 dm_put_path_selector(pst);
555 ti->error = "path selector constructor failed";
556 return r;
557 }
558
559 pg->ps.type = pst;
560 dm_consume_args(as, ps_argc);
561
562 return 0;
563}
564
565static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps,
566 struct dm_target *ti)
567{
568 int r;
569 struct pgpath *p;
570 struct multipath *m = ti->private;
571
572 /* we need at least a path arg */
573 if (as->argc < 1) {
574 ti->error = "no device given";
575 return ERR_PTR(-EINVAL);
576 }
577
578 p = alloc_pgpath();
579 if (!p)
580 return ERR_PTR(-ENOMEM);
581
582 r = dm_get_device(ti, dm_shift_arg(as), dm_table_get_mode(ti->table),
583 &p->path.dev);
584 if (r) {
585 ti->error = "error getting device";
586 goto bad;
587 }
588
589 if (m->hw_handler_name) {
590 struct request_queue *q = bdev_get_queue(p->path.dev->bdev);
591
592 r = scsi_dh_attach(q, m->hw_handler_name);
593 if (r == -EBUSY) {
594 /*
595 * Already attached to different hw_handler,
596 * try to reattach with correct one.
597 */
598 scsi_dh_detach(q);
599 r = scsi_dh_attach(q, m->hw_handler_name);
600 }
601
602 if (r < 0) {
603 ti->error = "error attaching hardware handler";
604 dm_put_device(ti, p->path.dev);
605 goto bad;
606 }
607
608 if (m->hw_handler_params) {
609 r = scsi_dh_set_params(q, m->hw_handler_params);
610 if (r < 0) {
611 ti->error = "unable to set hardware "
612 "handler parameters";
613 scsi_dh_detach(q);
614 dm_put_device(ti, p->path.dev);
615 goto bad;
616 }
617 }
618 }
619
620 r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
621 if (r) {
622 dm_put_device(ti, p->path.dev);
623 goto bad;
624 }
625
626 return p;
627
628 bad:
629 free_pgpath(p);
630 return ERR_PTR(r);
631}
632
633static struct priority_group *parse_priority_group(struct dm_arg_set *as,
634 struct multipath *m)
635{
636 static struct dm_arg _args[] = {
637 {1, 1024, "invalid number of paths"},
638 {0, 1024, "invalid number of selector args"}
639 };
640
641 int r;
642 unsigned i, nr_selector_args, nr_args;
643 struct priority_group *pg;
644 struct dm_target *ti = m->ti;
645
646 if (as->argc < 2) {
647 as->argc = 0;
648 ti->error = "not enough priority group arguments";
649 return ERR_PTR(-EINVAL);
650 }
651
652 pg = alloc_priority_group();
653 if (!pg) {
654 ti->error = "couldn't allocate priority group";
655 return ERR_PTR(-ENOMEM);
656 }
657 pg->m = m;
658
659 r = parse_path_selector(as, pg, ti);
660 if (r)
661 goto bad;
662
663 /*
664 * read the paths
665 */
666 r = dm_read_arg(_args, as, &pg->nr_pgpaths, &ti->error);
667 if (r)
668 goto bad;
669
670 r = dm_read_arg(_args + 1, as, &nr_selector_args, &ti->error);
671 if (r)
672 goto bad;
673
674 nr_args = 1 + nr_selector_args;
675 for (i = 0; i < pg->nr_pgpaths; i++) {
676 struct pgpath *pgpath;
677 struct dm_arg_set path_args;
678
679 if (as->argc < nr_args) {
680 ti->error = "not enough path parameters";
681 r = -EINVAL;
682 goto bad;
683 }
684
685 path_args.argc = nr_args;
686 path_args.argv = as->argv;
687
688 pgpath = parse_path(&path_args, &pg->ps, ti);
689 if (IS_ERR(pgpath)) {
690 r = PTR_ERR(pgpath);
691 goto bad;
692 }
693
694 pgpath->pg = pg;
695 list_add_tail(&pgpath->list, &pg->pgpaths);
696 dm_consume_args(as, nr_args);
697 }
698
699 return pg;
700
701 bad:
702 free_priority_group(pg, ti);
703 return ERR_PTR(r);
704}
705
706static int parse_hw_handler(struct dm_arg_set *as, struct multipath *m)
707{
708 unsigned hw_argc;
709 int ret;
710 struct dm_target *ti = m->ti;
711
712 static struct dm_arg _args[] = {
713 {0, 1024, "invalid number of hardware handler args"},
714 };
715
716 if (dm_read_arg_group(_args, as, &hw_argc, &ti->error))
717 return -EINVAL;
718
719 if (!hw_argc)
720 return 0;
721
722 m->hw_handler_name = kstrdup(dm_shift_arg(as), GFP_KERNEL);
723 if (!try_then_request_module(scsi_dh_handler_exist(m->hw_handler_name),
724 "scsi_dh_%s", m->hw_handler_name)) {
725 ti->error = "unknown hardware handler type";
726 ret = -EINVAL;
727 goto fail;
728 }
729
730 if (hw_argc > 1) {
731 char *p;
732 int i, j, len = 4;
733
734 for (i = 0; i <= hw_argc - 2; i++)
735 len += strlen(as->argv[i]) + 1;
736 p = m->hw_handler_params = kzalloc(len, GFP_KERNEL);
737 if (!p) {
738 ti->error = "memory allocation failed";
739 ret = -ENOMEM;
740 goto fail;
741 }
742 j = sprintf(p, "%d", hw_argc - 1);
743 for (i = 0, p+=j+1; i <= hw_argc - 2; i++, p+=j+1)
744 j = sprintf(p, "%s", as->argv[i]);
745 }
746 dm_consume_args(as, hw_argc - 1);
747
748 return 0;
749fail:
750 kfree(m->hw_handler_name);
751 m->hw_handler_name = NULL;
752 return ret;
753}
754
755static int parse_features(struct dm_arg_set *as, struct multipath *m)
756{
757 int r;
758 unsigned argc;
759 struct dm_target *ti = m->ti;
760 const char *arg_name;
761
762 static struct dm_arg _args[] = {
763 {0, 5, "invalid number of feature args"},
764 {1, 50, "pg_init_retries must be between 1 and 50"},
765 {0, 60000, "pg_init_delay_msecs must be between 0 and 60000"},
766 };
767
768 r = dm_read_arg_group(_args, as, &argc, &ti->error);
769 if (r)
770 return -EINVAL;
771
772 if (!argc)
773 return 0;
774
775 do {
776 arg_name = dm_shift_arg(as);
777 argc--;
778
779 if (!strcasecmp(arg_name, "queue_if_no_path")) {
780 r = queue_if_no_path(m, 1, 0);
781 continue;
782 }
783
784 if (!strcasecmp(arg_name, "pg_init_retries") &&
785 (argc >= 1)) {
786 r = dm_read_arg(_args + 1, as, &m->pg_init_retries, &ti->error);
787 argc--;
788 continue;
789 }
790
791 if (!strcasecmp(arg_name, "pg_init_delay_msecs") &&
792 (argc >= 1)) {
793 r = dm_read_arg(_args + 2, as, &m->pg_init_delay_msecs, &ti->error);
794 argc--;
795 continue;
796 }
797
798 ti->error = "Unrecognised multipath feature request";
799 r = -EINVAL;
800 } while (argc && !r);
801
802 return r;
803}
804
805static int multipath_ctr(struct dm_target *ti, unsigned int argc,
806 char **argv)
807{
808 /* target arguments */
809 static struct dm_arg _args[] = {
810 {0, 1024, "invalid number of priority groups"},
811 {0, 1024, "invalid initial priority group number"},
812 };
813
814 int r;
815 struct multipath *m;
816 struct dm_arg_set as;
817 unsigned pg_count = 0;
818 unsigned next_pg_num;
819
820 as.argc = argc;
821 as.argv = argv;
822
823 m = alloc_multipath(ti);
824 if (!m) {
825 ti->error = "can't allocate multipath";
826 return -EINVAL;
827 }
828
829 r = parse_features(&as, m);
830 if (r)
831 goto bad;
832
833 r = parse_hw_handler(&as, m);
834 if (r)
835 goto bad;
836
837 r = dm_read_arg(_args, &as, &m->nr_priority_groups, &ti->error);
838 if (r)
839 goto bad;
840
841 r = dm_read_arg(_args + 1, &as, &next_pg_num, &ti->error);
842 if (r)
843 goto bad;
844
845 if ((!m->nr_priority_groups && next_pg_num) ||
846 (m->nr_priority_groups && !next_pg_num)) {
847 ti->error = "invalid initial priority group";
848 r = -EINVAL;
849 goto bad;
850 }
851
852 /* parse the priority groups */
853 while (as.argc) {
854 struct priority_group *pg;
855
856 pg = parse_priority_group(&as, m);
857 if (IS_ERR(pg)) {
858 r = PTR_ERR(pg);
859 goto bad;
860 }
861
862 m->nr_valid_paths += pg->nr_pgpaths;
863 list_add_tail(&pg->list, &m->priority_groups);
864 pg_count++;
865 pg->pg_num = pg_count;
866 if (!--next_pg_num)
867 m->next_pg = pg;
868 }
869
870 if (pg_count != m->nr_priority_groups) {
871 ti->error = "priority group count mismatch";
872 r = -EINVAL;
873 goto bad;
874 }
875
876 ti->num_flush_requests = 1;
877 ti->num_discard_requests = 1;
878
879 return 0;
880
881 bad:
882 free_multipath(m);
883 return r;
884}
885
886static void multipath_wait_for_pg_init_completion(struct multipath *m)
887{
888 DECLARE_WAITQUEUE(wait, current);
889 unsigned long flags;
890
891 add_wait_queue(&m->pg_init_wait, &wait);
892
893 while (1) {
894 set_current_state(TASK_UNINTERRUPTIBLE);
895
896 spin_lock_irqsave(&m->lock, flags);
897 if (!m->pg_init_in_progress) {
898 spin_unlock_irqrestore(&m->lock, flags);
899 break;
900 }
901 spin_unlock_irqrestore(&m->lock, flags);
902
903 io_schedule();
904 }
905 set_current_state(TASK_RUNNING);
906
907 remove_wait_queue(&m->pg_init_wait, &wait);
908}
909
910static void flush_multipath_work(struct multipath *m)
911{
912 flush_workqueue(kmpath_handlerd);
913 multipath_wait_for_pg_init_completion(m);
914 flush_workqueue(kmultipathd);
915 flush_work_sync(&m->trigger_event);
916}
917
918static void multipath_dtr(struct dm_target *ti)
919{
920 struct multipath *m = ti->private;
921
922 flush_multipath_work(m);
923 free_multipath(m);
924}
925
926/*
927 * Map cloned requests
928 */
929static int multipath_map(struct dm_target *ti, struct request *clone,
930 union map_info *map_context)
931{
932 int r;
933 struct multipath *m = (struct multipath *) ti->private;
934
935 if (set_mapinfo(m, map_context) < 0)
936 /* ENOMEM, requeue */
937 return DM_MAPIO_REQUEUE;
938
939 clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
940 r = map_io(m, clone, map_context, 0);
941 if (r < 0 || r == DM_MAPIO_REQUEUE)
942 clear_mapinfo(m, map_context);
943
944 return r;
945}
946
947/*
948 * Take a path out of use.
949 */
950static int fail_path(struct pgpath *pgpath)
951{
952 unsigned long flags;
953 struct multipath *m = pgpath->pg->m;
954
955 spin_lock_irqsave(&m->lock, flags);
956
957 if (!pgpath->is_active)
958 goto out;
959
960 DMWARN("Failing path %s.", pgpath->path.dev->name);
961
962 pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
963 pgpath->is_active = 0;
964 pgpath->fail_count++;
965
966 m->nr_valid_paths--;
967
968 if (pgpath == m->current_pgpath)
969 m->current_pgpath = NULL;
970
971 dm_path_uevent(DM_UEVENT_PATH_FAILED, m->ti,
972 pgpath->path.dev->name, m->nr_valid_paths);
973
974 schedule_work(&m->trigger_event);
975
976out:
977 spin_unlock_irqrestore(&m->lock, flags);
978
979 return 0;
980}
981
982/*
983 * Reinstate a previously-failed path
984 */
985static int reinstate_path(struct pgpath *pgpath)
986{
987 int r = 0;
988 unsigned long flags;
989 struct multipath *m = pgpath->pg->m;
990
991 spin_lock_irqsave(&m->lock, flags);
992
993 if (pgpath->is_active)
994 goto out;
995
996 if (!pgpath->pg->ps.type->reinstate_path) {
997 DMWARN("Reinstate path not supported by path selector %s",
998 pgpath->pg->ps.type->name);
999 r = -EINVAL;
1000 goto out;
1001 }
1002
1003 r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
1004 if (r)
1005 goto out;
1006
1007 pgpath->is_active = 1;
1008
1009 if (!m->nr_valid_paths++ && m->queue_size) {
1010 m->current_pgpath = NULL;
1011 queue_work(kmultipathd, &m->process_queued_ios);
1012 } else if (m->hw_handler_name && (m->current_pg == pgpath->pg)) {
1013 if (queue_work(kmpath_handlerd, &pgpath->activate_path.work))
1014 m->pg_init_in_progress++;
1015 }
1016
1017 dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti,
1018 pgpath->path.dev->name, m->nr_valid_paths);
1019
1020 schedule_work(&m->trigger_event);
1021
1022out:
1023 spin_unlock_irqrestore(&m->lock, flags);
1024
1025 return r;
1026}
1027
1028/*
1029 * Fail or reinstate all paths that match the provided struct dm_dev.
1030 */
1031static int action_dev(struct multipath *m, struct dm_dev *dev,
1032 action_fn action)
1033{
1034 int r = -EINVAL;
1035 struct pgpath *pgpath;
1036 struct priority_group *pg;
1037
1038 list_for_each_entry(pg, &m->priority_groups, list) {
1039 list_for_each_entry(pgpath, &pg->pgpaths, list) {
1040 if (pgpath->path.dev == dev)
1041 r = action(pgpath);
1042 }
1043 }
1044
1045 return r;
1046}
1047
1048/*
1049 * Temporarily try to avoid having to use the specified PG
1050 */
1051static void bypass_pg(struct multipath *m, struct priority_group *pg,
1052 int bypassed)
1053{
1054 unsigned long flags;
1055
1056 spin_lock_irqsave(&m->lock, flags);
1057
1058 pg->bypassed = bypassed;
1059 m->current_pgpath = NULL;
1060 m->current_pg = NULL;
1061
1062 spin_unlock_irqrestore(&m->lock, flags);
1063
1064 schedule_work(&m->trigger_event);
1065}
1066
1067/*
1068 * Switch to using the specified PG from the next I/O that gets mapped
1069 */
1070static int switch_pg_num(struct multipath *m, const char *pgstr)
1071{
1072 struct priority_group *pg;
1073 unsigned pgnum;
1074 unsigned long flags;
1075 char dummy;
1076
1077 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1078 (pgnum > m->nr_priority_groups)) {
1079 DMWARN("invalid PG number supplied to switch_pg_num");
1080 return -EINVAL;
1081 }
1082
1083 spin_lock_irqsave(&m->lock, flags);
1084 list_for_each_entry(pg, &m->priority_groups, list) {
1085 pg->bypassed = 0;
1086 if (--pgnum)
1087 continue;
1088
1089 m->current_pgpath = NULL;
1090 m->current_pg = NULL;
1091 m->next_pg = pg;
1092 }
1093 spin_unlock_irqrestore(&m->lock, flags);
1094
1095 schedule_work(&m->trigger_event);
1096 return 0;
1097}
1098
1099/*
1100 * Set/clear bypassed status of a PG.
1101 * PGs are numbered upwards from 1 in the order they were declared.
1102 */
1103static int bypass_pg_num(struct multipath *m, const char *pgstr, int bypassed)
1104{
1105 struct priority_group *pg;
1106 unsigned pgnum;
1107 char dummy;
1108
1109 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1110 (pgnum > m->nr_priority_groups)) {
1111 DMWARN("invalid PG number supplied to bypass_pg");
1112 return -EINVAL;
1113 }
1114
1115 list_for_each_entry(pg, &m->priority_groups, list) {
1116 if (!--pgnum)
1117 break;
1118 }
1119
1120 bypass_pg(m, pg, bypassed);
1121 return 0;
1122}
1123
1124/*
1125 * Should we retry pg_init immediately?
1126 */
1127static int pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath)
1128{
1129 unsigned long flags;
1130 int limit_reached = 0;
1131
1132 spin_lock_irqsave(&m->lock, flags);
1133
1134 if (m->pg_init_count <= m->pg_init_retries)
1135 m->pg_init_required = 1;
1136 else
1137 limit_reached = 1;
1138
1139 spin_unlock_irqrestore(&m->lock, flags);
1140
1141 return limit_reached;
1142}
1143
1144static void pg_init_done(void *data, int errors)
1145{
1146 struct pgpath *pgpath = data;
1147 struct priority_group *pg = pgpath->pg;
1148 struct multipath *m = pg->m;
1149 unsigned long flags;
1150 unsigned delay_retry = 0;
1151
1152 /* device or driver problems */
1153 switch (errors) {
1154 case SCSI_DH_OK:
1155 break;
1156 case SCSI_DH_NOSYS:
1157 if (!m->hw_handler_name) {
1158 errors = 0;
1159 break;
1160 }
1161 DMERR("Could not failover the device: Handler scsi_dh_%s "
1162 "Error %d.", m->hw_handler_name, errors);
1163 /*
1164 * Fail path for now, so we do not ping pong
1165 */
1166 fail_path(pgpath);
1167 break;
1168 case SCSI_DH_DEV_TEMP_BUSY:
1169 /*
1170 * Probably doing something like FW upgrade on the
1171 * controller so try the other pg.
1172 */
1173 bypass_pg(m, pg, 1);
1174 break;
1175 case SCSI_DH_RETRY:
1176 /* Wait before retrying. */
1177 delay_retry = 1;
1178 case SCSI_DH_IMM_RETRY:
1179 case SCSI_DH_RES_TEMP_UNAVAIL:
1180 if (pg_init_limit_reached(m, pgpath))
1181 fail_path(pgpath);
1182 errors = 0;
1183 break;
1184 default:
1185 /*
1186 * We probably do not want to fail the path for a device
1187 * error, but this is what the old dm did. In future
1188 * patches we can do more advanced handling.
1189 */
1190 fail_path(pgpath);
1191 }
1192
1193 spin_lock_irqsave(&m->lock, flags);
1194 if (errors) {
1195 if (pgpath == m->current_pgpath) {
1196 DMERR("Could not failover device. Error %d.", errors);
1197 m->current_pgpath = NULL;
1198 m->current_pg = NULL;
1199 }
1200 } else if (!m->pg_init_required)
1201 pg->bypassed = 0;
1202
1203 if (--m->pg_init_in_progress)
1204 /* Activations of other paths are still on going */
1205 goto out;
1206
1207 if (!m->pg_init_required)
1208 m->queue_io = 0;
1209
1210 m->pg_init_delay_retry = delay_retry;
1211 queue_work(kmultipathd, &m->process_queued_ios);
1212
1213 /*
1214 * Wake up any thread waiting to suspend.
1215 */
1216 wake_up(&m->pg_init_wait);
1217
1218out:
1219 spin_unlock_irqrestore(&m->lock, flags);
1220}
1221
1222static void activate_path(struct work_struct *work)
1223{
1224 struct pgpath *pgpath =
1225 container_of(work, struct pgpath, activate_path.work);
1226
1227 scsi_dh_activate(bdev_get_queue(pgpath->path.dev->bdev),
1228 pg_init_done, pgpath);
1229}
1230
1231/*
1232 * end_io handling
1233 */
1234static int do_end_io(struct multipath *m, struct request *clone,
1235 int error, struct dm_mpath_io *mpio)
1236{
1237 /*
1238 * We don't queue any clone request inside the multipath target
1239 * during end I/O handling, since those clone requests don't have
1240 * bio clones. If we queue them inside the multipath target,
1241 * we need to make bio clones, that requires memory allocation.
1242 * (See drivers/md/dm.c:end_clone_bio() about why the clone requests
1243 * don't have bio clones.)
1244 * Instead of queueing the clone request here, we queue the original
1245 * request into dm core, which will remake a clone request and
1246 * clone bios for it and resubmit it later.
1247 */
1248 int r = DM_ENDIO_REQUEUE;
1249 unsigned long flags;
1250
1251 if (!error && !clone->errors)
1252 return 0; /* I/O complete */
1253
1254 if (error == -EOPNOTSUPP || error == -EREMOTEIO || error == -EILSEQ)
1255 return error;
1256
1257 if (mpio->pgpath)
1258 fail_path(mpio->pgpath);
1259
1260 spin_lock_irqsave(&m->lock, flags);
1261 if (!m->nr_valid_paths) {
1262 if (!m->queue_if_no_path) {
1263 if (!__must_push_back(m))
1264 r = -EIO;
1265 } else {
1266 if (error == -EBADE)
1267 r = error;
1268 }
1269 }
1270 spin_unlock_irqrestore(&m->lock, flags);
1271
1272 return r;
1273}
1274
1275static int multipath_end_io(struct dm_target *ti, struct request *clone,
1276 int error, union map_info *map_context)
1277{
1278 struct multipath *m = ti->private;
1279 struct dm_mpath_io *mpio = map_context->ptr;
1280 struct pgpath *pgpath = mpio->pgpath;
1281 struct path_selector *ps;
1282 int r;
1283
1284 BUG_ON(!mpio);
1285
1286 r = do_end_io(m, clone, error, mpio);
1287 if (pgpath) {
1288 ps = &pgpath->pg->ps;
1289 if (ps->type->end_io)
1290 ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
1291 }
1292 clear_mapinfo(m, map_context);
1293
1294 return r;
1295}
1296
1297/*
1298 * Suspend can't complete until all the I/O is processed so if
1299 * the last path fails we must error any remaining I/O.
1300 * Note that if the freeze_bdev fails while suspending, the
1301 * queue_if_no_path state is lost - userspace should reset it.
1302 */
1303static void multipath_presuspend(struct dm_target *ti)
1304{
1305 struct multipath *m = (struct multipath *) ti->private;
1306
1307 queue_if_no_path(m, 0, 1);
1308}
1309
1310static void multipath_postsuspend(struct dm_target *ti)
1311{
1312 struct multipath *m = ti->private;
1313
1314 mutex_lock(&m->work_mutex);
1315 flush_multipath_work(m);
1316 mutex_unlock(&m->work_mutex);
1317}
1318
1319/*
1320 * Restore the queue_if_no_path setting.
1321 */
1322static void multipath_resume(struct dm_target *ti)
1323{
1324 struct multipath *m = (struct multipath *) ti->private;
1325 unsigned long flags;
1326
1327 spin_lock_irqsave(&m->lock, flags);
1328 m->queue_if_no_path = m->saved_queue_if_no_path;
1329 spin_unlock_irqrestore(&m->lock, flags);
1330}
1331
1332/*
1333 * Info output has the following format:
1334 * num_multipath_feature_args [multipath_feature_args]*
1335 * num_handler_status_args [handler_status_args]*
1336 * num_groups init_group_number
1337 * [A|D|E num_ps_status_args [ps_status_args]*
1338 * num_paths num_selector_args
1339 * [path_dev A|F fail_count [selector_args]* ]+ ]+
1340 *
1341 * Table output has the following format (identical to the constructor string):
1342 * num_feature_args [features_args]*
1343 * num_handler_args hw_handler [hw_handler_args]*
1344 * num_groups init_group_number
1345 * [priority selector-name num_ps_args [ps_args]*
1346 * num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
1347 */
1348static int multipath_status(struct dm_target *ti, status_type_t type,
1349 char *result, unsigned int maxlen)
1350{
1351 int sz = 0;
1352 unsigned long flags;
1353 struct multipath *m = (struct multipath *) ti->private;
1354 struct priority_group *pg;
1355 struct pgpath *p;
1356 unsigned pg_num;
1357 char state;
1358
1359 spin_lock_irqsave(&m->lock, flags);
1360
1361 /* Features */
1362 if (type == STATUSTYPE_INFO)
1363 DMEMIT("2 %u %u ", m->queue_size, m->pg_init_count);
1364 else {
1365 DMEMIT("%u ", m->queue_if_no_path +
1366 (m->pg_init_retries > 0) * 2 +
1367 (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT) * 2);
1368 if (m->queue_if_no_path)
1369 DMEMIT("queue_if_no_path ");
1370 if (m->pg_init_retries)
1371 DMEMIT("pg_init_retries %u ", m->pg_init_retries);
1372 if (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT)
1373 DMEMIT("pg_init_delay_msecs %u ", m->pg_init_delay_msecs);
1374 }
1375
1376 if (!m->hw_handler_name || type == STATUSTYPE_INFO)
1377 DMEMIT("0 ");
1378 else
1379 DMEMIT("1 %s ", m->hw_handler_name);
1380
1381 DMEMIT("%u ", m->nr_priority_groups);
1382
1383 if (m->next_pg)
1384 pg_num = m->next_pg->pg_num;
1385 else if (m->current_pg)
1386 pg_num = m->current_pg->pg_num;
1387 else
1388 pg_num = (m->nr_priority_groups ? 1 : 0);
1389
1390 DMEMIT("%u ", pg_num);
1391
1392 switch (type) {
1393 case STATUSTYPE_INFO:
1394 list_for_each_entry(pg, &m->priority_groups, list) {
1395 if (pg->bypassed)
1396 state = 'D'; /* Disabled */
1397 else if (pg == m->current_pg)
1398 state = 'A'; /* Currently Active */
1399 else
1400 state = 'E'; /* Enabled */
1401
1402 DMEMIT("%c ", state);
1403
1404 if (pg->ps.type->status)
1405 sz += pg->ps.type->status(&pg->ps, NULL, type,
1406 result + sz,
1407 maxlen - sz);
1408 else
1409 DMEMIT("0 ");
1410
1411 DMEMIT("%u %u ", pg->nr_pgpaths,
1412 pg->ps.type->info_args);
1413
1414 list_for_each_entry(p, &pg->pgpaths, list) {
1415 DMEMIT("%s %s %u ", p->path.dev->name,
1416 p->is_active ? "A" : "F",
1417 p->fail_count);
1418 if (pg->ps.type->status)
1419 sz += pg->ps.type->status(&pg->ps,
1420 &p->path, type, result + sz,
1421 maxlen - sz);
1422 }
1423 }
1424 break;
1425
1426 case STATUSTYPE_TABLE:
1427 list_for_each_entry(pg, &m->priority_groups, list) {
1428 DMEMIT("%s ", pg->ps.type->name);
1429
1430 if (pg->ps.type->status)
1431 sz += pg->ps.type->status(&pg->ps, NULL, type,
1432 result + sz,
1433 maxlen - sz);
1434 else
1435 DMEMIT("0 ");
1436
1437 DMEMIT("%u %u ", pg->nr_pgpaths,
1438 pg->ps.type->table_args);
1439
1440 list_for_each_entry(p, &pg->pgpaths, list) {
1441 DMEMIT("%s ", p->path.dev->name);
1442 if (pg->ps.type->status)
1443 sz += pg->ps.type->status(&pg->ps,
1444 &p->path, type, result + sz,
1445 maxlen - sz);
1446 }
1447 }
1448 break;
1449 }
1450
1451 spin_unlock_irqrestore(&m->lock, flags);
1452
1453 return 0;
1454}
1455
1456static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
1457{
1458 int r = -EINVAL;
1459 struct dm_dev *dev;
1460 struct multipath *m = (struct multipath *) ti->private;
1461 action_fn action;
1462
1463 mutex_lock(&m->work_mutex);
1464
1465 if (dm_suspended(ti)) {
1466 r = -EBUSY;
1467 goto out;
1468 }
1469
1470 if (argc == 1) {
1471 if (!strcasecmp(argv[0], "queue_if_no_path")) {
1472 r = queue_if_no_path(m, 1, 0);
1473 goto out;
1474 } else if (!strcasecmp(argv[0], "fail_if_no_path")) {
1475 r = queue_if_no_path(m, 0, 0);
1476 goto out;
1477 }
1478 }
1479
1480 if (argc != 2) {
1481 DMWARN("Unrecognised multipath message received.");
1482 goto out;
1483 }
1484
1485 if (!strcasecmp(argv[0], "disable_group")) {
1486 r = bypass_pg_num(m, argv[1], 1);
1487 goto out;
1488 } else if (!strcasecmp(argv[0], "enable_group")) {
1489 r = bypass_pg_num(m, argv[1], 0);
1490 goto out;
1491 } else if (!strcasecmp(argv[0], "switch_group")) {
1492 r = switch_pg_num(m, argv[1]);
1493 goto out;
1494 } else if (!strcasecmp(argv[0], "reinstate_path"))
1495 action = reinstate_path;
1496 else if (!strcasecmp(argv[0], "fail_path"))
1497 action = fail_path;
1498 else {
1499 DMWARN("Unrecognised multipath message received.");
1500 goto out;
1501 }
1502
1503 r = dm_get_device(ti, argv[1], dm_table_get_mode(ti->table), &dev);
1504 if (r) {
1505 DMWARN("message: error getting device %s",
1506 argv[1]);
1507 goto out;
1508 }
1509
1510 r = action_dev(m, dev, action);
1511
1512 dm_put_device(ti, dev);
1513
1514out:
1515 mutex_unlock(&m->work_mutex);
1516 return r;
1517}
1518
1519static int multipath_ioctl(struct dm_target *ti, unsigned int cmd,
1520 unsigned long arg)
1521{
1522 struct multipath *m = ti->private;
1523 struct pgpath *pgpath;
1524 struct block_device *bdev;
1525 fmode_t mode;
1526 unsigned long flags;
1527 int r;
1528
1529again:
1530 bdev = NULL;
1531 mode = 0;
1532 r = 0;
1533
1534 spin_lock_irqsave(&m->lock, flags);
1535
1536 if (!m->current_pgpath)
1537 __choose_pgpath(m, 0);
1538
1539 pgpath = m->current_pgpath;
1540
1541 if (pgpath) {
1542 bdev = pgpath->path.dev->bdev;
1543 mode = pgpath->path.dev->mode;
1544 }
1545
1546 if ((pgpath && m->queue_io) || (!pgpath && m->queue_if_no_path))
1547 r = -EAGAIN;
1548 else if (!bdev)
1549 r = -EIO;
1550
1551 spin_unlock_irqrestore(&m->lock, flags);
1552
1553 /*
1554 * Only pass ioctls through if the device sizes match exactly.
1555 */
1556 if (!r && ti->len != i_size_read(bdev->bd_inode) >> SECTOR_SHIFT)
1557 r = scsi_verify_blk_ioctl(NULL, cmd);
1558
1559 if (r == -EAGAIN && !fatal_signal_pending(current)) {
1560 queue_work(kmultipathd, &m->process_queued_ios);
1561 msleep(10);
1562 goto again;
1563 }
1564
1565 return r ? : __blkdev_driver_ioctl(bdev, mode, cmd, arg);
1566}
1567
1568static int multipath_iterate_devices(struct dm_target *ti,
1569 iterate_devices_callout_fn fn, void *data)
1570{
1571 struct multipath *m = ti->private;
1572 struct priority_group *pg;
1573 struct pgpath *p;
1574 int ret = 0;
1575
1576 list_for_each_entry(pg, &m->priority_groups, list) {
1577 list_for_each_entry(p, &pg->pgpaths, list) {
1578 ret = fn(ti, p->path.dev, ti->begin, ti->len, data);
1579 if (ret)
1580 goto out;
1581 }
1582 }
1583
1584out:
1585 return ret;
1586}
1587
1588static int __pgpath_busy(struct pgpath *pgpath)
1589{
1590 struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
1591
1592 return dm_underlying_device_busy(q);
1593}
1594
1595/*
1596 * We return "busy", only when we can map I/Os but underlying devices
1597 * are busy (so even if we map I/Os now, the I/Os will wait on
1598 * the underlying queue).
1599 * In other words, if we want to kill I/Os or queue them inside us
1600 * due to map unavailability, we don't return "busy". Otherwise,
1601 * dm core won't give us the I/Os and we can't do what we want.
1602 */
1603static int multipath_busy(struct dm_target *ti)
1604{
1605 int busy = 0, has_active = 0;
1606 struct multipath *m = ti->private;
1607 struct priority_group *pg;
1608 struct pgpath *pgpath;
1609 unsigned long flags;
1610
1611 spin_lock_irqsave(&m->lock, flags);
1612
1613 /* Guess which priority_group will be used at next mapping time */
1614 if (unlikely(!m->current_pgpath && m->next_pg))
1615 pg = m->next_pg;
1616 else if (likely(m->current_pg))
1617 pg = m->current_pg;
1618 else
1619 /*
1620 * We don't know which pg will be used at next mapping time.
1621 * We don't call __choose_pgpath() here to avoid to trigger
1622 * pg_init just by busy checking.
1623 * So we don't know whether underlying devices we will be using
1624 * at next mapping time are busy or not. Just try mapping.
1625 */
1626 goto out;
1627
1628 /*
1629 * If there is one non-busy active path at least, the path selector
1630 * will be able to select it. So we consider such a pg as not busy.
1631 */
1632 busy = 1;
1633 list_for_each_entry(pgpath, &pg->pgpaths, list)
1634 if (pgpath->is_active) {
1635 has_active = 1;
1636
1637 if (!__pgpath_busy(pgpath)) {
1638 busy = 0;
1639 break;
1640 }
1641 }
1642
1643 if (!has_active)
1644 /*
1645 * No active path in this pg, so this pg won't be used and
1646 * the current_pg will be changed at next mapping time.
1647 * We need to try mapping to determine it.
1648 */
1649 busy = 0;
1650
1651out:
1652 spin_unlock_irqrestore(&m->lock, flags);
1653
1654 return busy;
1655}
1656
1657/*-----------------------------------------------------------------
1658 * Module setup
1659 *---------------------------------------------------------------*/
1660static struct target_type multipath_target = {
1661 .name = "multipath",
1662 .version = {1, 4, 0},
1663 .module = THIS_MODULE,
1664 .ctr = multipath_ctr,
1665 .dtr = multipath_dtr,
1666 .map_rq = multipath_map,
1667 .rq_end_io = multipath_end_io,
1668 .presuspend = multipath_presuspend,
1669 .postsuspend = multipath_postsuspend,
1670 .resume = multipath_resume,
1671 .status = multipath_status,
1672 .message = multipath_message,
1673 .ioctl = multipath_ioctl,
1674 .iterate_devices = multipath_iterate_devices,
1675 .busy = multipath_busy,
1676};
1677
1678static int __init dm_multipath_init(void)
1679{
1680 int r;
1681
1682 /* allocate a slab for the dm_ios */
1683 _mpio_cache = KMEM_CACHE(dm_mpath_io, 0);
1684 if (!_mpio_cache)
1685 return -ENOMEM;
1686
1687 r = dm_register_target(&multipath_target);
1688 if (r < 0) {
1689 DMERR("register failed %d", r);
1690 kmem_cache_destroy(_mpio_cache);
1691 return -EINVAL;
1692 }
1693
1694 kmultipathd = alloc_workqueue("kmpathd", WQ_MEM_RECLAIM, 0);
1695 if (!kmultipathd) {
1696 DMERR("failed to create workqueue kmpathd");
1697 dm_unregister_target(&multipath_target);
1698 kmem_cache_destroy(_mpio_cache);
1699 return -ENOMEM;
1700 }
1701
1702 /*
1703 * A separate workqueue is used to handle the device handlers
1704 * to avoid overloading existing workqueue. Overloading the
1705 * old workqueue would also create a bottleneck in the
1706 * path of the storage hardware device activation.
1707 */
1708 kmpath_handlerd = alloc_ordered_workqueue("kmpath_handlerd",
1709 WQ_MEM_RECLAIM);
1710 if (!kmpath_handlerd) {
1711 DMERR("failed to create workqueue kmpath_handlerd");
1712 destroy_workqueue(kmultipathd);
1713 dm_unregister_target(&multipath_target);
1714 kmem_cache_destroy(_mpio_cache);
1715 return -ENOMEM;
1716 }
1717
1718 DMINFO("version %u.%u.%u loaded",
1719 multipath_target.version[0], multipath_target.version[1],
1720 multipath_target.version[2]);
1721
1722 return r;
1723}
1724
1725static void __exit dm_multipath_exit(void)
1726{
1727 destroy_workqueue(kmpath_handlerd);
1728 destroy_workqueue(kmultipathd);
1729
1730 dm_unregister_target(&multipath_target);
1731 kmem_cache_destroy(_mpio_cache);
1732}
1733
1734module_init(dm_multipath_init);
1735module_exit(dm_multipath_exit);
1736
1737MODULE_DESCRIPTION(DM_NAME " multipath target");
1738MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
1739MODULE_LICENSE("GPL");