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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(&bios, &m->queued_bios);
708 bio_list_init(&m->queued_bios);
709
710 spin_unlock_irqrestore(&m->lock, flags);
711
712 blk_start_plug(&plug);
713 while ((bio = bio_list_pop(&bios))) {
714 struct dm_mpath_io *mpio = get_mpio_from_bio(bio);
715
716 dm_bio_restore(get_bio_details_from_mpio(mpio), bio);
717 r = __multipath_map_bio(m, bio, mpio);
718 switch (r) {
719 case DM_MAPIO_KILL:
720 bio->bi_status = BLK_STS_IOERR;
721 bio_endio(bio);
722 break;
723 case DM_MAPIO_REQUEUE:
724 bio->bi_status = BLK_STS_DM_REQUEUE;
725 bio_endio(bio);
726 break;
727 case DM_MAPIO_REMAPPED:
728 submit_bio_noacct(bio);
729 break;
730 case DM_MAPIO_SUBMITTED:
731 break;
732 default:
733 WARN_ONCE(true, "__multipath_map_bio() returned %d\n", r);
734 }
735 }
736 blk_finish_plug(&plug);
737}
738
739/*
740 * If we run out of usable paths, should we queue I/O or error it?
741 */
742static int queue_if_no_path(struct multipath *m, bool f_queue_if_no_path,
743 bool save_old_value, const char *caller)
744{
745 unsigned long flags;
746 bool queue_if_no_path_bit, saved_queue_if_no_path_bit;
747 const char *dm_dev_name = dm_table_device_name(m->ti->table);
748
749 DMDEBUG("%s: %s caller=%s f_queue_if_no_path=%d save_old_value=%d",
750 dm_dev_name, __func__, caller, f_queue_if_no_path, save_old_value);
751
752 spin_lock_irqsave(&m->lock, flags);
753
754 queue_if_no_path_bit = test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
755 saved_queue_if_no_path_bit = test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
756
757 if (save_old_value) {
758 if (unlikely(!queue_if_no_path_bit && saved_queue_if_no_path_bit)) {
759 DMERR("%s: QIFNP disabled but saved as enabled, saving again loses state, not saving!",
760 dm_dev_name);
761 } else
762 assign_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags, queue_if_no_path_bit);
763 } else if (!f_queue_if_no_path && saved_queue_if_no_path_bit) {
764 /* due to "fail_if_no_path" message, need to honor it. */
765 clear_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
766 }
767 assign_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags, f_queue_if_no_path);
768
769 DMDEBUG("%s: after %s changes; QIFNP = %d; SQIFNP = %d; DNFS = %d",
770 dm_dev_name, __func__,
771 test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags),
772 test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags),
773 dm_noflush_suspending(m->ti));
774
775 spin_unlock_irqrestore(&m->lock, flags);
776
777 if (!f_queue_if_no_path) {
778 dm_table_run_md_queue_async(m->ti->table);
779 process_queued_io_list(m);
780 }
781
782 return 0;
783}
784
785/*
786 * If the queue_if_no_path timeout fires, turn off queue_if_no_path and
787 * process any queued I/O.
788 */
789static void queue_if_no_path_timeout_work(struct timer_list *t)
790{
791 struct multipath *m = from_timer(m, t, nopath_timer);
792
793 DMWARN("queue_if_no_path timeout on %s, failing queued IO",
794 dm_table_device_name(m->ti->table));
795 queue_if_no_path(m, false, false, __func__);
796}
797
798/*
799 * Enable the queue_if_no_path timeout if necessary.
800 * Called with m->lock held.
801 */
802static void enable_nopath_timeout(struct multipath *m)
803{
804 unsigned long queue_if_no_path_timeout =
805 READ_ONCE(queue_if_no_path_timeout_secs) * HZ;
806
807 lockdep_assert_held(&m->lock);
808
809 if (queue_if_no_path_timeout > 0 &&
810 atomic_read(&m->nr_valid_paths) == 0 &&
811 test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
812 mod_timer(&m->nopath_timer,
813 jiffies + queue_if_no_path_timeout);
814 }
815}
816
817static void disable_nopath_timeout(struct multipath *m)
818{
819 del_timer_sync(&m->nopath_timer);
820}
821
822/*
823 * An event is triggered whenever a path is taken out of use.
824 * Includes path failure and PG bypass.
825 */
826static void trigger_event(struct work_struct *work)
827{
828 struct multipath *m =
829 container_of(work, struct multipath, trigger_event);
830
831 dm_table_event(m->ti->table);
832}
833
834/*
835 *---------------------------------------------------------------
836 * Constructor/argument parsing:
837 * <#multipath feature args> [<arg>]*
838 * <#hw_handler args> [hw_handler [<arg>]*]
839 * <#priority groups>
840 * <initial priority group>
841 * [<selector> <#selector args> [<arg>]*
842 * <#paths> <#per-path selector args>
843 * [<path> [<arg>]* ]+ ]+
844 *---------------------------------------------------------------
845 */
846static int parse_path_selector(struct dm_arg_set *as, struct priority_group *pg,
847 struct dm_target *ti)
848{
849 int r;
850 struct path_selector_type *pst;
851 unsigned int ps_argc;
852
853 static const struct dm_arg _args[] = {
854 {0, 1024, "invalid number of path selector args"},
855 };
856
857 pst = dm_get_path_selector(dm_shift_arg(as));
858 if (!pst) {
859 ti->error = "unknown path selector type";
860 return -EINVAL;
861 }
862
863 r = dm_read_arg_group(_args, as, &ps_argc, &ti->error);
864 if (r) {
865 dm_put_path_selector(pst);
866 return -EINVAL;
867 }
868
869 r = pst->create(&pg->ps, ps_argc, as->argv);
870 if (r) {
871 dm_put_path_selector(pst);
872 ti->error = "path selector constructor failed";
873 return r;
874 }
875
876 pg->ps.type = pst;
877 dm_consume_args(as, ps_argc);
878
879 return 0;
880}
881
882static int setup_scsi_dh(struct block_device *bdev, struct multipath *m,
883 const char **attached_handler_name, char **error)
884{
885 struct request_queue *q = bdev_get_queue(bdev);
886 int r;
887
888 if (mpath_double_check_test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, m)) {
889retain:
890 if (*attached_handler_name) {
891 /*
892 * Clear any hw_handler_params associated with a
893 * handler that isn't already attached.
894 */
895 if (m->hw_handler_name && strcmp(*attached_handler_name, m->hw_handler_name)) {
896 kfree(m->hw_handler_params);
897 m->hw_handler_params = NULL;
898 }
899
900 /*
901 * Reset hw_handler_name to match the attached handler
902 *
903 * NB. This modifies the table line to show the actual
904 * handler instead of the original table passed in.
905 */
906 kfree(m->hw_handler_name);
907 m->hw_handler_name = *attached_handler_name;
908 *attached_handler_name = NULL;
909 }
910 }
911
912 if (m->hw_handler_name) {
913 r = scsi_dh_attach(q, m->hw_handler_name);
914 if (r == -EBUSY) {
915 DMINFO("retaining handler on device %pg", bdev);
916 goto retain;
917 }
918 if (r < 0) {
919 *error = "error attaching hardware handler";
920 return r;
921 }
922
923 if (m->hw_handler_params) {
924 r = scsi_dh_set_params(q, m->hw_handler_params);
925 if (r < 0) {
926 *error = "unable to set hardware handler parameters";
927 return r;
928 }
929 }
930 }
931
932 return 0;
933}
934
935static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps,
936 struct dm_target *ti)
937{
938 int r;
939 struct pgpath *p;
940 struct multipath *m = ti->private;
941 struct request_queue *q;
942 const char *attached_handler_name = NULL;
943
944 /* we need at least a path arg */
945 if (as->argc < 1) {
946 ti->error = "no device given";
947 return ERR_PTR(-EINVAL);
948 }
949
950 p = alloc_pgpath();
951 if (!p)
952 return ERR_PTR(-ENOMEM);
953
954 r = dm_get_device(ti, dm_shift_arg(as), dm_table_get_mode(ti->table),
955 &p->path.dev);
956 if (r) {
957 ti->error = "error getting device";
958 goto bad;
959 }
960
961 q = bdev_get_queue(p->path.dev->bdev);
962 attached_handler_name = scsi_dh_attached_handler_name(q, GFP_KERNEL);
963 if (attached_handler_name || m->hw_handler_name) {
964 INIT_DELAYED_WORK(&p->activate_path, activate_path_work);
965 r = setup_scsi_dh(p->path.dev->bdev, m, &attached_handler_name, &ti->error);
966 kfree(attached_handler_name);
967 if (r) {
968 dm_put_device(ti, p->path.dev);
969 goto bad;
970 }
971 }
972
973 r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
974 if (r) {
975 dm_put_device(ti, p->path.dev);
976 goto bad;
977 }
978
979 return p;
980 bad:
981 free_pgpath(p);
982 return ERR_PTR(r);
983}
984
985static struct priority_group *parse_priority_group(struct dm_arg_set *as,
986 struct multipath *m)
987{
988 static const struct dm_arg _args[] = {
989 {1, 1024, "invalid number of paths"},
990 {0, 1024, "invalid number of selector args"}
991 };
992
993 int r;
994 unsigned int i, nr_selector_args, nr_args;
995 struct priority_group *pg;
996 struct dm_target *ti = m->ti;
997
998 if (as->argc < 2) {
999 as->argc = 0;
1000 ti->error = "not enough priority group arguments";
1001 return ERR_PTR(-EINVAL);
1002 }
1003
1004 pg = alloc_priority_group();
1005 if (!pg) {
1006 ti->error = "couldn't allocate priority group";
1007 return ERR_PTR(-ENOMEM);
1008 }
1009 pg->m = m;
1010
1011 r = parse_path_selector(as, pg, ti);
1012 if (r)
1013 goto bad;
1014
1015 /*
1016 * read the paths
1017 */
1018 r = dm_read_arg(_args, as, &pg->nr_pgpaths, &ti->error);
1019 if (r)
1020 goto bad;
1021
1022 r = dm_read_arg(_args + 1, as, &nr_selector_args, &ti->error);
1023 if (r)
1024 goto bad;
1025
1026 nr_args = 1 + nr_selector_args;
1027 for (i = 0; i < pg->nr_pgpaths; i++) {
1028 struct pgpath *pgpath;
1029 struct dm_arg_set path_args;
1030
1031 if (as->argc < nr_args) {
1032 ti->error = "not enough path parameters";
1033 r = -EINVAL;
1034 goto bad;
1035 }
1036
1037 path_args.argc = nr_args;
1038 path_args.argv = as->argv;
1039
1040 pgpath = parse_path(&path_args, &pg->ps, ti);
1041 if (IS_ERR(pgpath)) {
1042 r = PTR_ERR(pgpath);
1043 goto bad;
1044 }
1045
1046 pgpath->pg = pg;
1047 list_add_tail(&pgpath->list, &pg->pgpaths);
1048 dm_consume_args(as, nr_args);
1049 }
1050
1051 return pg;
1052
1053 bad:
1054 free_priority_group(pg, ti);
1055 return ERR_PTR(r);
1056}
1057
1058static int parse_hw_handler(struct dm_arg_set *as, struct multipath *m)
1059{
1060 unsigned int hw_argc;
1061 int ret;
1062 struct dm_target *ti = m->ti;
1063
1064 static const struct dm_arg _args[] = {
1065 {0, 1024, "invalid number of hardware handler args"},
1066 };
1067
1068 if (dm_read_arg_group(_args, as, &hw_argc, &ti->error))
1069 return -EINVAL;
1070
1071 if (!hw_argc)
1072 return 0;
1073
1074 if (m->queue_mode == DM_TYPE_BIO_BASED) {
1075 dm_consume_args(as, hw_argc);
1076 DMERR("bio-based multipath doesn't allow hardware handler args");
1077 return 0;
1078 }
1079
1080 m->hw_handler_name = kstrdup(dm_shift_arg(as), GFP_KERNEL);
1081 if (!m->hw_handler_name)
1082 return -EINVAL;
1083
1084 if (hw_argc > 1) {
1085 char *p;
1086 int i, j, len = 4;
1087
1088 for (i = 0; i <= hw_argc - 2; i++)
1089 len += strlen(as->argv[i]) + 1;
1090 p = m->hw_handler_params = kzalloc(len, GFP_KERNEL);
1091 if (!p) {
1092 ti->error = "memory allocation failed";
1093 ret = -ENOMEM;
1094 goto fail;
1095 }
1096 j = sprintf(p, "%d", hw_argc - 1);
1097 for (i = 0, p += j + 1; i <= hw_argc - 2; i++, p += j + 1)
1098 j = sprintf(p, "%s", as->argv[i]);
1099 }
1100 dm_consume_args(as, hw_argc - 1);
1101
1102 return 0;
1103fail:
1104 kfree(m->hw_handler_name);
1105 m->hw_handler_name = NULL;
1106 return ret;
1107}
1108
1109static int parse_features(struct dm_arg_set *as, struct multipath *m)
1110{
1111 int r;
1112 unsigned int argc;
1113 struct dm_target *ti = m->ti;
1114 const char *arg_name;
1115
1116 static const struct dm_arg _args[] = {
1117 {0, 8, "invalid number of feature args"},
1118 {1, 50, "pg_init_retries must be between 1 and 50"},
1119 {0, 60000, "pg_init_delay_msecs must be between 0 and 60000"},
1120 };
1121
1122 r = dm_read_arg_group(_args, as, &argc, &ti->error);
1123 if (r)
1124 return -EINVAL;
1125
1126 if (!argc)
1127 return 0;
1128
1129 do {
1130 arg_name = dm_shift_arg(as);
1131 argc--;
1132
1133 if (!strcasecmp(arg_name, "queue_if_no_path")) {
1134 r = queue_if_no_path(m, true, false, __func__);
1135 continue;
1136 }
1137
1138 if (!strcasecmp(arg_name, "retain_attached_hw_handler")) {
1139 set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags);
1140 continue;
1141 }
1142
1143 if (!strcasecmp(arg_name, "pg_init_retries") &&
1144 (argc >= 1)) {
1145 r = dm_read_arg(_args + 1, as, &m->pg_init_retries, &ti->error);
1146 argc--;
1147 continue;
1148 }
1149
1150 if (!strcasecmp(arg_name, "pg_init_delay_msecs") &&
1151 (argc >= 1)) {
1152 r = dm_read_arg(_args + 2, as, &m->pg_init_delay_msecs, &ti->error);
1153 argc--;
1154 continue;
1155 }
1156
1157 if (!strcasecmp(arg_name, "queue_mode") &&
1158 (argc >= 1)) {
1159 const char *queue_mode_name = dm_shift_arg(as);
1160
1161 if (!strcasecmp(queue_mode_name, "bio"))
1162 m->queue_mode = DM_TYPE_BIO_BASED;
1163 else if (!strcasecmp(queue_mode_name, "rq") ||
1164 !strcasecmp(queue_mode_name, "mq"))
1165 m->queue_mode = DM_TYPE_REQUEST_BASED;
1166 else {
1167 ti->error = "Unknown 'queue_mode' requested";
1168 r = -EINVAL;
1169 }
1170 argc--;
1171 continue;
1172 }
1173
1174 ti->error = "Unrecognised multipath feature request";
1175 r = -EINVAL;
1176 } while (argc && !r);
1177
1178 return r;
1179}
1180
1181static int multipath_ctr(struct dm_target *ti, unsigned int argc, char **argv)
1182{
1183 /* target arguments */
1184 static const struct dm_arg _args[] = {
1185 {0, 1024, "invalid number of priority groups"},
1186 {0, 1024, "invalid initial priority group number"},
1187 };
1188
1189 int r;
1190 struct multipath *m;
1191 struct dm_arg_set as;
1192 unsigned int pg_count = 0;
1193 unsigned int next_pg_num;
1194 unsigned long flags;
1195
1196 as.argc = argc;
1197 as.argv = argv;
1198
1199 m = alloc_multipath(ti);
1200 if (!m) {
1201 ti->error = "can't allocate multipath";
1202 return -EINVAL;
1203 }
1204
1205 r = parse_features(&as, m);
1206 if (r)
1207 goto bad;
1208
1209 r = alloc_multipath_stage2(ti, m);
1210 if (r)
1211 goto bad;
1212
1213 r = parse_hw_handler(&as, m);
1214 if (r)
1215 goto bad;
1216
1217 r = dm_read_arg(_args, &as, &m->nr_priority_groups, &ti->error);
1218 if (r)
1219 goto bad;
1220
1221 r = dm_read_arg(_args + 1, &as, &next_pg_num, &ti->error);
1222 if (r)
1223 goto bad;
1224
1225 if ((!m->nr_priority_groups && next_pg_num) ||
1226 (m->nr_priority_groups && !next_pg_num)) {
1227 ti->error = "invalid initial priority group";
1228 r = -EINVAL;
1229 goto bad;
1230 }
1231
1232 /* parse the priority groups */
1233 while (as.argc) {
1234 struct priority_group *pg;
1235 unsigned int nr_valid_paths = atomic_read(&m->nr_valid_paths);
1236
1237 pg = parse_priority_group(&as, m);
1238 if (IS_ERR(pg)) {
1239 r = PTR_ERR(pg);
1240 goto bad;
1241 }
1242
1243 nr_valid_paths += pg->nr_pgpaths;
1244 atomic_set(&m->nr_valid_paths, nr_valid_paths);
1245
1246 list_add_tail(&pg->list, &m->priority_groups);
1247 pg_count++;
1248 pg->pg_num = pg_count;
1249 if (!--next_pg_num)
1250 m->next_pg = pg;
1251 }
1252
1253 if (pg_count != m->nr_priority_groups) {
1254 ti->error = "priority group count mismatch";
1255 r = -EINVAL;
1256 goto bad;
1257 }
1258
1259 spin_lock_irqsave(&m->lock, flags);
1260 enable_nopath_timeout(m);
1261 spin_unlock_irqrestore(&m->lock, flags);
1262
1263 ti->num_flush_bios = 1;
1264 ti->num_discard_bios = 1;
1265 ti->num_write_zeroes_bios = 1;
1266 if (m->queue_mode == DM_TYPE_BIO_BASED)
1267 ti->per_io_data_size = multipath_per_bio_data_size();
1268 else
1269 ti->per_io_data_size = sizeof(struct dm_mpath_io);
1270
1271 return 0;
1272
1273 bad:
1274 free_multipath(m);
1275 return r;
1276}
1277
1278static void multipath_wait_for_pg_init_completion(struct multipath *m)
1279{
1280 DEFINE_WAIT(wait);
1281
1282 while (1) {
1283 prepare_to_wait(&m->pg_init_wait, &wait, TASK_UNINTERRUPTIBLE);
1284
1285 if (!atomic_read(&m->pg_init_in_progress))
1286 break;
1287
1288 io_schedule();
1289 }
1290 finish_wait(&m->pg_init_wait, &wait);
1291}
1292
1293static void flush_multipath_work(struct multipath *m)
1294{
1295 if (m->hw_handler_name) {
1296 unsigned long flags;
1297
1298 if (!atomic_read(&m->pg_init_in_progress))
1299 goto skip;
1300
1301 spin_lock_irqsave(&m->lock, flags);
1302 if (atomic_read(&m->pg_init_in_progress) &&
1303 !test_and_set_bit(MPATHF_PG_INIT_DISABLED, &m->flags)) {
1304 spin_unlock_irqrestore(&m->lock, flags);
1305
1306 flush_workqueue(kmpath_handlerd);
1307 multipath_wait_for_pg_init_completion(m);
1308
1309 spin_lock_irqsave(&m->lock, flags);
1310 clear_bit(MPATHF_PG_INIT_DISABLED, &m->flags);
1311 }
1312 spin_unlock_irqrestore(&m->lock, flags);
1313 }
1314skip:
1315 if (m->queue_mode == DM_TYPE_BIO_BASED)
1316 flush_work(&m->process_queued_bios);
1317 flush_work(&m->trigger_event);
1318}
1319
1320static void multipath_dtr(struct dm_target *ti)
1321{
1322 struct multipath *m = ti->private;
1323
1324 disable_nopath_timeout(m);
1325 flush_multipath_work(m);
1326 free_multipath(m);
1327}
1328
1329/*
1330 * Take a path out of use.
1331 */
1332static int fail_path(struct pgpath *pgpath)
1333{
1334 unsigned long flags;
1335 struct multipath *m = pgpath->pg->m;
1336
1337 spin_lock_irqsave(&m->lock, flags);
1338
1339 if (!pgpath->is_active)
1340 goto out;
1341
1342 DMWARN("%s: Failing path %s.",
1343 dm_table_device_name(m->ti->table),
1344 pgpath->path.dev->name);
1345
1346 pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
1347 pgpath->is_active = false;
1348 pgpath->fail_count++;
1349
1350 atomic_dec(&m->nr_valid_paths);
1351
1352 if (pgpath == m->current_pgpath)
1353 m->current_pgpath = NULL;
1354
1355 dm_path_uevent(DM_UEVENT_PATH_FAILED, m->ti,
1356 pgpath->path.dev->name, atomic_read(&m->nr_valid_paths));
1357
1358 queue_work(dm_mpath_wq, &m->trigger_event);
1359
1360 enable_nopath_timeout(m);
1361
1362out:
1363 spin_unlock_irqrestore(&m->lock, flags);
1364
1365 return 0;
1366}
1367
1368/*
1369 * Reinstate a previously-failed path
1370 */
1371static int reinstate_path(struct pgpath *pgpath)
1372{
1373 int r = 0, run_queue = 0;
1374 unsigned long flags;
1375 struct multipath *m = pgpath->pg->m;
1376 unsigned int nr_valid_paths;
1377
1378 spin_lock_irqsave(&m->lock, flags);
1379
1380 if (pgpath->is_active)
1381 goto out;
1382
1383 DMWARN("%s: Reinstating path %s.",
1384 dm_table_device_name(m->ti->table),
1385 pgpath->path.dev->name);
1386
1387 r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
1388 if (r)
1389 goto out;
1390
1391 pgpath->is_active = true;
1392
1393 nr_valid_paths = atomic_inc_return(&m->nr_valid_paths);
1394 if (nr_valid_paths == 1) {
1395 m->current_pgpath = NULL;
1396 run_queue = 1;
1397 } else if (m->hw_handler_name && (m->current_pg == pgpath->pg)) {
1398 if (queue_work(kmpath_handlerd, &pgpath->activate_path.work))
1399 atomic_inc(&m->pg_init_in_progress);
1400 }
1401
1402 dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti,
1403 pgpath->path.dev->name, nr_valid_paths);
1404
1405 schedule_work(&m->trigger_event);
1406
1407out:
1408 spin_unlock_irqrestore(&m->lock, flags);
1409 if (run_queue) {
1410 dm_table_run_md_queue_async(m->ti->table);
1411 process_queued_io_list(m);
1412 }
1413
1414 if (pgpath->is_active)
1415 disable_nopath_timeout(m);
1416
1417 return r;
1418}
1419
1420/*
1421 * Fail or reinstate all paths that match the provided struct dm_dev.
1422 */
1423static int action_dev(struct multipath *m, struct dm_dev *dev,
1424 action_fn action)
1425{
1426 int r = -EINVAL;
1427 struct pgpath *pgpath;
1428 struct priority_group *pg;
1429
1430 list_for_each_entry(pg, &m->priority_groups, list) {
1431 list_for_each_entry(pgpath, &pg->pgpaths, list) {
1432 if (pgpath->path.dev == dev)
1433 r = action(pgpath);
1434 }
1435 }
1436
1437 return r;
1438}
1439
1440/*
1441 * Temporarily try to avoid having to use the specified PG
1442 */
1443static void bypass_pg(struct multipath *m, struct priority_group *pg,
1444 bool bypassed)
1445{
1446 unsigned long flags;
1447
1448 spin_lock_irqsave(&m->lock, flags);
1449
1450 pg->bypassed = bypassed;
1451 m->current_pgpath = NULL;
1452 m->current_pg = NULL;
1453
1454 spin_unlock_irqrestore(&m->lock, flags);
1455
1456 schedule_work(&m->trigger_event);
1457}
1458
1459/*
1460 * Switch to using the specified PG from the next I/O that gets mapped
1461 */
1462static int switch_pg_num(struct multipath *m, const char *pgstr)
1463{
1464 struct priority_group *pg;
1465 unsigned int pgnum;
1466 unsigned long flags;
1467 char dummy;
1468
1469 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1470 !m->nr_priority_groups || (pgnum > m->nr_priority_groups)) {
1471 DMWARN("invalid PG number supplied to %s", __func__);
1472 return -EINVAL;
1473 }
1474
1475 spin_lock_irqsave(&m->lock, flags);
1476 list_for_each_entry(pg, &m->priority_groups, list) {
1477 pg->bypassed = false;
1478 if (--pgnum)
1479 continue;
1480
1481 m->current_pgpath = NULL;
1482 m->current_pg = NULL;
1483 m->next_pg = pg;
1484 }
1485 spin_unlock_irqrestore(&m->lock, flags);
1486
1487 schedule_work(&m->trigger_event);
1488 return 0;
1489}
1490
1491/*
1492 * Set/clear bypassed status of a PG.
1493 * PGs are numbered upwards from 1 in the order they were declared.
1494 */
1495static int bypass_pg_num(struct multipath *m, const char *pgstr, bool bypassed)
1496{
1497 struct priority_group *pg;
1498 unsigned int pgnum;
1499 char dummy;
1500
1501 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1502 !m->nr_priority_groups || (pgnum > m->nr_priority_groups)) {
1503 DMWARN("invalid PG number supplied to bypass_pg");
1504 return -EINVAL;
1505 }
1506
1507 list_for_each_entry(pg, &m->priority_groups, list) {
1508 if (!--pgnum)
1509 break;
1510 }
1511
1512 bypass_pg(m, pg, bypassed);
1513 return 0;
1514}
1515
1516/*
1517 * Should we retry pg_init immediately?
1518 */
1519static bool pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath)
1520{
1521 unsigned long flags;
1522 bool limit_reached = false;
1523
1524 spin_lock_irqsave(&m->lock, flags);
1525
1526 if (atomic_read(&m->pg_init_count) <= m->pg_init_retries &&
1527 !test_bit(MPATHF_PG_INIT_DISABLED, &m->flags))
1528 set_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
1529 else
1530 limit_reached = true;
1531
1532 spin_unlock_irqrestore(&m->lock, flags);
1533
1534 return limit_reached;
1535}
1536
1537static void pg_init_done(void *data, int errors)
1538{
1539 struct pgpath *pgpath = data;
1540 struct priority_group *pg = pgpath->pg;
1541 struct multipath *m = pg->m;
1542 unsigned long flags;
1543 bool delay_retry = false;
1544
1545 /* device or driver problems */
1546 switch (errors) {
1547 case SCSI_DH_OK:
1548 break;
1549 case SCSI_DH_NOSYS:
1550 if (!m->hw_handler_name) {
1551 errors = 0;
1552 break;
1553 }
1554 DMERR("Could not failover the device: Handler scsi_dh_%s "
1555 "Error %d.", m->hw_handler_name, errors);
1556 /*
1557 * Fail path for now, so we do not ping pong
1558 */
1559 fail_path(pgpath);
1560 break;
1561 case SCSI_DH_DEV_TEMP_BUSY:
1562 /*
1563 * Probably doing something like FW upgrade on the
1564 * controller so try the other pg.
1565 */
1566 bypass_pg(m, pg, true);
1567 break;
1568 case SCSI_DH_RETRY:
1569 /* Wait before retrying. */
1570 delay_retry = true;
1571 fallthrough;
1572 case SCSI_DH_IMM_RETRY:
1573 case SCSI_DH_RES_TEMP_UNAVAIL:
1574 if (pg_init_limit_reached(m, pgpath))
1575 fail_path(pgpath);
1576 errors = 0;
1577 break;
1578 case SCSI_DH_DEV_OFFLINED:
1579 default:
1580 /*
1581 * We probably do not want to fail the path for a device
1582 * error, but this is what the old dm did. In future
1583 * patches we can do more advanced handling.
1584 */
1585 fail_path(pgpath);
1586 }
1587
1588 spin_lock_irqsave(&m->lock, flags);
1589 if (errors) {
1590 if (pgpath == m->current_pgpath) {
1591 DMERR("Could not failover device. Error %d.", errors);
1592 m->current_pgpath = NULL;
1593 m->current_pg = NULL;
1594 }
1595 } else if (!test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
1596 pg->bypassed = false;
1597
1598 if (atomic_dec_return(&m->pg_init_in_progress) > 0)
1599 /* Activations of other paths are still on going */
1600 goto out;
1601
1602 if (test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags)) {
1603 if (delay_retry)
1604 set_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
1605 else
1606 clear_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
1607
1608 if (__pg_init_all_paths(m))
1609 goto out;
1610 }
1611 clear_bit(MPATHF_QUEUE_IO, &m->flags);
1612
1613 process_queued_io_list(m);
1614
1615 /*
1616 * Wake up any thread waiting to suspend.
1617 */
1618 wake_up(&m->pg_init_wait);
1619
1620out:
1621 spin_unlock_irqrestore(&m->lock, flags);
1622}
1623
1624static void activate_or_offline_path(struct pgpath *pgpath)
1625{
1626 struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
1627
1628 if (pgpath->is_active && !blk_queue_dying(q))
1629 scsi_dh_activate(q, pg_init_done, pgpath);
1630 else
1631 pg_init_done(pgpath, SCSI_DH_DEV_OFFLINED);
1632}
1633
1634static void activate_path_work(struct work_struct *work)
1635{
1636 struct pgpath *pgpath =
1637 container_of(work, struct pgpath, activate_path.work);
1638
1639 activate_or_offline_path(pgpath);
1640}
1641
1642static int multipath_end_io(struct dm_target *ti, struct request *clone,
1643 blk_status_t error, union map_info *map_context)
1644{
1645 struct dm_mpath_io *mpio = get_mpio(map_context);
1646 struct pgpath *pgpath = mpio->pgpath;
1647 int r = DM_ENDIO_DONE;
1648
1649 /*
1650 * We don't queue any clone request inside the multipath target
1651 * during end I/O handling, since those clone requests don't have
1652 * bio clones. If we queue them inside the multipath target,
1653 * we need to make bio clones, that requires memory allocation.
1654 * (See drivers/md/dm-rq.c:end_clone_bio() about why the clone requests
1655 * don't have bio clones.)
1656 * Instead of queueing the clone request here, we queue the original
1657 * request into dm core, which will remake a clone request and
1658 * clone bios for it and resubmit it later.
1659 */
1660 if (error && blk_path_error(error)) {
1661 struct multipath *m = ti->private;
1662
1663 if (error == BLK_STS_RESOURCE)
1664 r = DM_ENDIO_DELAY_REQUEUE;
1665 else
1666 r = DM_ENDIO_REQUEUE;
1667
1668 if (pgpath)
1669 fail_path(pgpath);
1670
1671 if (!atomic_read(&m->nr_valid_paths) &&
1672 !must_push_back_rq(m)) {
1673 if (error == BLK_STS_IOERR)
1674 dm_report_EIO(m);
1675 /* complete with the original error */
1676 r = DM_ENDIO_DONE;
1677 }
1678 }
1679
1680 if (pgpath) {
1681 struct path_selector *ps = &pgpath->pg->ps;
1682
1683 if (ps->type->end_io)
1684 ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes,
1685 clone->io_start_time_ns);
1686 }
1687
1688 return r;
1689}
1690
1691static int multipath_end_io_bio(struct dm_target *ti, struct bio *clone,
1692 blk_status_t *error)
1693{
1694 struct multipath *m = ti->private;
1695 struct dm_mpath_io *mpio = get_mpio_from_bio(clone);
1696 struct pgpath *pgpath = mpio->pgpath;
1697 unsigned long flags;
1698 int r = DM_ENDIO_DONE;
1699
1700 if (!*error || !blk_path_error(*error))
1701 goto done;
1702
1703 if (pgpath)
1704 fail_path(pgpath);
1705
1706 if (!atomic_read(&m->nr_valid_paths)) {
1707 spin_lock_irqsave(&m->lock, flags);
1708 if (!test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
1709 if (__must_push_back(m)) {
1710 r = DM_ENDIO_REQUEUE;
1711 } else {
1712 dm_report_EIO(m);
1713 *error = BLK_STS_IOERR;
1714 }
1715 spin_unlock_irqrestore(&m->lock, flags);
1716 goto done;
1717 }
1718 spin_unlock_irqrestore(&m->lock, flags);
1719 }
1720
1721 multipath_queue_bio(m, clone);
1722 r = DM_ENDIO_INCOMPLETE;
1723done:
1724 if (pgpath) {
1725 struct path_selector *ps = &pgpath->pg->ps;
1726
1727 if (ps->type->end_io)
1728 ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes,
1729 (mpio->start_time_ns ?:
1730 dm_start_time_ns_from_clone(clone)));
1731 }
1732
1733 return r;
1734}
1735
1736/*
1737 * Suspend with flush can't complete until all the I/O is processed
1738 * so if the last path fails we must error any remaining I/O.
1739 * - Note that if the freeze_bdev fails while suspending, the
1740 * queue_if_no_path state is lost - userspace should reset it.
1741 * Otherwise, during noflush suspend, queue_if_no_path will not change.
1742 */
1743static void multipath_presuspend(struct dm_target *ti)
1744{
1745 struct multipath *m = ti->private;
1746
1747 /* FIXME: bio-based shouldn't need to always disable queue_if_no_path */
1748 if (m->queue_mode == DM_TYPE_BIO_BASED || !dm_noflush_suspending(m->ti))
1749 queue_if_no_path(m, false, true, __func__);
1750}
1751
1752static void multipath_postsuspend(struct dm_target *ti)
1753{
1754 struct multipath *m = ti->private;
1755
1756 mutex_lock(&m->work_mutex);
1757 flush_multipath_work(m);
1758 mutex_unlock(&m->work_mutex);
1759}
1760
1761/*
1762 * Restore the queue_if_no_path setting.
1763 */
1764static void multipath_resume(struct dm_target *ti)
1765{
1766 struct multipath *m = ti->private;
1767 unsigned long flags;
1768
1769 spin_lock_irqsave(&m->lock, flags);
1770 if (test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags)) {
1771 set_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
1772 clear_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
1773 }
1774
1775 DMDEBUG("%s: %s finished; QIFNP = %d; SQIFNP = %d",
1776 dm_table_device_name(m->ti->table), __func__,
1777 test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags),
1778 test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags));
1779
1780 spin_unlock_irqrestore(&m->lock, flags);
1781}
1782
1783/*
1784 * Info output has the following format:
1785 * num_multipath_feature_args [multipath_feature_args]*
1786 * num_handler_status_args [handler_status_args]*
1787 * num_groups init_group_number
1788 * [A|D|E num_ps_status_args [ps_status_args]*
1789 * num_paths num_selector_args
1790 * [path_dev A|F fail_count [selector_args]* ]+ ]+
1791 *
1792 * Table output has the following format (identical to the constructor string):
1793 * num_feature_args [features_args]*
1794 * num_handler_args hw_handler [hw_handler_args]*
1795 * num_groups init_group_number
1796 * [priority selector-name num_ps_args [ps_args]*
1797 * num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
1798 */
1799static void multipath_status(struct dm_target *ti, status_type_t type,
1800 unsigned int status_flags, char *result, unsigned int maxlen)
1801{
1802 int sz = 0, pg_counter, pgpath_counter;
1803 unsigned long flags;
1804 struct multipath *m = ti->private;
1805 struct priority_group *pg;
1806 struct pgpath *p;
1807 unsigned int pg_num;
1808 char state;
1809
1810 spin_lock_irqsave(&m->lock, flags);
1811
1812 /* Features */
1813 if (type == STATUSTYPE_INFO)
1814 DMEMIT("2 %u %u ", test_bit(MPATHF_QUEUE_IO, &m->flags),
1815 atomic_read(&m->pg_init_count));
1816 else {
1817 DMEMIT("%u ", test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) +
1818 (m->pg_init_retries > 0) * 2 +
1819 (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT) * 2 +
1820 test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags) +
1821 (m->queue_mode != DM_TYPE_REQUEST_BASED) * 2);
1822
1823 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
1824 DMEMIT("queue_if_no_path ");
1825 if (m->pg_init_retries)
1826 DMEMIT("pg_init_retries %u ", m->pg_init_retries);
1827 if (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT)
1828 DMEMIT("pg_init_delay_msecs %u ", m->pg_init_delay_msecs);
1829 if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags))
1830 DMEMIT("retain_attached_hw_handler ");
1831 if (m->queue_mode != DM_TYPE_REQUEST_BASED) {
1832 switch (m->queue_mode) {
1833 case DM_TYPE_BIO_BASED:
1834 DMEMIT("queue_mode bio ");
1835 break;
1836 default:
1837 WARN_ON_ONCE(true);
1838 break;
1839 }
1840 }
1841 }
1842
1843 if (!m->hw_handler_name || type == STATUSTYPE_INFO)
1844 DMEMIT("0 ");
1845 else
1846 DMEMIT("1 %s ", m->hw_handler_name);
1847
1848 DMEMIT("%u ", m->nr_priority_groups);
1849
1850 if (m->next_pg)
1851 pg_num = m->next_pg->pg_num;
1852 else if (m->current_pg)
1853 pg_num = m->current_pg->pg_num;
1854 else
1855 pg_num = (m->nr_priority_groups ? 1 : 0);
1856
1857 DMEMIT("%u ", pg_num);
1858
1859 switch (type) {
1860 case STATUSTYPE_INFO:
1861 list_for_each_entry(pg, &m->priority_groups, list) {
1862 if (pg->bypassed)
1863 state = 'D'; /* Disabled */
1864 else if (pg == m->current_pg)
1865 state = 'A'; /* Currently Active */
1866 else
1867 state = 'E'; /* Enabled */
1868
1869 DMEMIT("%c ", state);
1870
1871 if (pg->ps.type->status)
1872 sz += pg->ps.type->status(&pg->ps, NULL, type,
1873 result + sz,
1874 maxlen - sz);
1875 else
1876 DMEMIT("0 ");
1877
1878 DMEMIT("%u %u ", pg->nr_pgpaths,
1879 pg->ps.type->info_args);
1880
1881 list_for_each_entry(p, &pg->pgpaths, list) {
1882 DMEMIT("%s %s %u ", p->path.dev->name,
1883 p->is_active ? "A" : "F",
1884 p->fail_count);
1885 if (pg->ps.type->status)
1886 sz += pg->ps.type->status(&pg->ps,
1887 &p->path, type, result + sz,
1888 maxlen - sz);
1889 }
1890 }
1891 break;
1892
1893 case STATUSTYPE_TABLE:
1894 list_for_each_entry(pg, &m->priority_groups, list) {
1895 DMEMIT("%s ", pg->ps.type->name);
1896
1897 if (pg->ps.type->status)
1898 sz += pg->ps.type->status(&pg->ps, NULL, type,
1899 result + sz,
1900 maxlen - sz);
1901 else
1902 DMEMIT("0 ");
1903
1904 DMEMIT("%u %u ", pg->nr_pgpaths,
1905 pg->ps.type->table_args);
1906
1907 list_for_each_entry(p, &pg->pgpaths, list) {
1908 DMEMIT("%s ", p->path.dev->name);
1909 if (pg->ps.type->status)
1910 sz += pg->ps.type->status(&pg->ps,
1911 &p->path, type, result + sz,
1912 maxlen - sz);
1913 }
1914 }
1915 break;
1916
1917 case STATUSTYPE_IMA:
1918 sz = 0; /*reset the result pointer*/
1919
1920 DMEMIT_TARGET_NAME_VERSION(ti->type);
1921 DMEMIT(",nr_priority_groups=%u", m->nr_priority_groups);
1922
1923 pg_counter = 0;
1924 list_for_each_entry(pg, &m->priority_groups, list) {
1925 if (pg->bypassed)
1926 state = 'D'; /* Disabled */
1927 else if (pg == m->current_pg)
1928 state = 'A'; /* Currently Active */
1929 else
1930 state = 'E'; /* Enabled */
1931 DMEMIT(",pg_state_%d=%c", pg_counter, state);
1932 DMEMIT(",nr_pgpaths_%d=%u", pg_counter, pg->nr_pgpaths);
1933 DMEMIT(",path_selector_name_%d=%s", pg_counter, pg->ps.type->name);
1934
1935 pgpath_counter = 0;
1936 list_for_each_entry(p, &pg->pgpaths, list) {
1937 DMEMIT(",path_name_%d_%d=%s,is_active_%d_%d=%c,fail_count_%d_%d=%u",
1938 pg_counter, pgpath_counter, p->path.dev->name,
1939 pg_counter, pgpath_counter, p->is_active ? 'A' : 'F',
1940 pg_counter, pgpath_counter, p->fail_count);
1941 if (pg->ps.type->status) {
1942 DMEMIT(",path_selector_status_%d_%d=",
1943 pg_counter, pgpath_counter);
1944 sz += pg->ps.type->status(&pg->ps, &p->path,
1945 type, result + sz,
1946 maxlen - sz);
1947 }
1948 pgpath_counter++;
1949 }
1950 pg_counter++;
1951 }
1952 DMEMIT(";");
1953 break;
1954 }
1955
1956 spin_unlock_irqrestore(&m->lock, flags);
1957}
1958
1959static int multipath_message(struct dm_target *ti, unsigned int argc, char **argv,
1960 char *result, unsigned int maxlen)
1961{
1962 int r = -EINVAL;
1963 struct dm_dev *dev;
1964 struct multipath *m = ti->private;
1965 action_fn action;
1966 unsigned long flags;
1967
1968 mutex_lock(&m->work_mutex);
1969
1970 if (dm_suspended(ti)) {
1971 r = -EBUSY;
1972 goto out;
1973 }
1974
1975 if (argc == 1) {
1976 if (!strcasecmp(argv[0], "queue_if_no_path")) {
1977 r = queue_if_no_path(m, true, false, __func__);
1978 spin_lock_irqsave(&m->lock, flags);
1979 enable_nopath_timeout(m);
1980 spin_unlock_irqrestore(&m->lock, flags);
1981 goto out;
1982 } else if (!strcasecmp(argv[0], "fail_if_no_path")) {
1983 r = queue_if_no_path(m, false, false, __func__);
1984 disable_nopath_timeout(m);
1985 goto out;
1986 }
1987 }
1988
1989 if (argc != 2) {
1990 DMWARN("Invalid multipath message arguments. Expected 2 arguments, got %d.", argc);
1991 goto out;
1992 }
1993
1994 if (!strcasecmp(argv[0], "disable_group")) {
1995 r = bypass_pg_num(m, argv[1], true);
1996 goto out;
1997 } else if (!strcasecmp(argv[0], "enable_group")) {
1998 r = bypass_pg_num(m, argv[1], false);
1999 goto out;
2000 } else if (!strcasecmp(argv[0], "switch_group")) {
2001 r = switch_pg_num(m, argv[1]);
2002 goto out;
2003 } else if (!strcasecmp(argv[0], "reinstate_path"))
2004 action = reinstate_path;
2005 else if (!strcasecmp(argv[0], "fail_path"))
2006 action = fail_path;
2007 else {
2008 DMWARN("Unrecognised multipath message received: %s", argv[0]);
2009 goto out;
2010 }
2011
2012 r = dm_get_device(ti, argv[1], dm_table_get_mode(ti->table), &dev);
2013 if (r) {
2014 DMWARN("message: error getting device %s",
2015 argv[1]);
2016 goto out;
2017 }
2018
2019 r = action_dev(m, dev, action);
2020
2021 dm_put_device(ti, dev);
2022
2023out:
2024 mutex_unlock(&m->work_mutex);
2025 return r;
2026}
2027
2028static int multipath_prepare_ioctl(struct dm_target *ti,
2029 struct block_device **bdev)
2030{
2031 struct multipath *m = ti->private;
2032 struct pgpath *pgpath;
2033 unsigned long flags;
2034 int r;
2035
2036 pgpath = READ_ONCE(m->current_pgpath);
2037 if (!pgpath || !mpath_double_check_test_bit(MPATHF_QUEUE_IO, m))
2038 pgpath = choose_pgpath(m, 0);
2039
2040 if (pgpath) {
2041 if (!mpath_double_check_test_bit(MPATHF_QUEUE_IO, m)) {
2042 *bdev = pgpath->path.dev->bdev;
2043 r = 0;
2044 } else {
2045 /* pg_init has not started or completed */
2046 r = -ENOTCONN;
2047 }
2048 } else {
2049 /* No path is available */
2050 r = -EIO;
2051 spin_lock_irqsave(&m->lock, flags);
2052 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
2053 r = -ENOTCONN;
2054 spin_unlock_irqrestore(&m->lock, flags);
2055 }
2056
2057 if (r == -ENOTCONN) {
2058 if (!READ_ONCE(m->current_pg)) {
2059 /* Path status changed, redo selection */
2060 (void) choose_pgpath(m, 0);
2061 }
2062 spin_lock_irqsave(&m->lock, flags);
2063 if (test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
2064 (void) __pg_init_all_paths(m);
2065 spin_unlock_irqrestore(&m->lock, flags);
2066 dm_table_run_md_queue_async(m->ti->table);
2067 process_queued_io_list(m);
2068 }
2069
2070 /*
2071 * Only pass ioctls through if the device sizes match exactly.
2072 */
2073 if (!r && ti->len != bdev_nr_sectors((*bdev)))
2074 return 1;
2075 return r;
2076}
2077
2078static int multipath_iterate_devices(struct dm_target *ti,
2079 iterate_devices_callout_fn fn, void *data)
2080{
2081 struct multipath *m = ti->private;
2082 struct priority_group *pg;
2083 struct pgpath *p;
2084 int ret = 0;
2085
2086 list_for_each_entry(pg, &m->priority_groups, list) {
2087 list_for_each_entry(p, &pg->pgpaths, list) {
2088 ret = fn(ti, p->path.dev, ti->begin, ti->len, data);
2089 if (ret)
2090 goto out;
2091 }
2092 }
2093
2094out:
2095 return ret;
2096}
2097
2098static int pgpath_busy(struct pgpath *pgpath)
2099{
2100 struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
2101
2102 return blk_lld_busy(q);
2103}
2104
2105/*
2106 * We return "busy", only when we can map I/Os but underlying devices
2107 * are busy (so even if we map I/Os now, the I/Os will wait on
2108 * the underlying queue).
2109 * In other words, if we want to kill I/Os or queue them inside us
2110 * due to map unavailability, we don't return "busy". Otherwise,
2111 * dm core won't give us the I/Os and we can't do what we want.
2112 */
2113static int multipath_busy(struct dm_target *ti)
2114{
2115 bool busy = false, has_active = false;
2116 struct multipath *m = ti->private;
2117 struct priority_group *pg, *next_pg;
2118 struct pgpath *pgpath;
2119
2120 /* pg_init in progress */
2121 if (atomic_read(&m->pg_init_in_progress))
2122 return true;
2123
2124 /* no paths available, for blk-mq: rely on IO mapping to delay requeue */
2125 if (!atomic_read(&m->nr_valid_paths)) {
2126 unsigned long flags;
2127
2128 spin_lock_irqsave(&m->lock, flags);
2129 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
2130 spin_unlock_irqrestore(&m->lock, flags);
2131 return (m->queue_mode != DM_TYPE_REQUEST_BASED);
2132 }
2133 spin_unlock_irqrestore(&m->lock, flags);
2134 }
2135
2136 /* Guess which priority_group will be used at next mapping time */
2137 pg = READ_ONCE(m->current_pg);
2138 next_pg = READ_ONCE(m->next_pg);
2139 if (unlikely(!READ_ONCE(m->current_pgpath) && next_pg))
2140 pg = next_pg;
2141
2142 if (!pg) {
2143 /*
2144 * We don't know which pg will be used at next mapping time.
2145 * We don't call choose_pgpath() here to avoid to trigger
2146 * pg_init just by busy checking.
2147 * So we don't know whether underlying devices we will be using
2148 * at next mapping time are busy or not. Just try mapping.
2149 */
2150 return busy;
2151 }
2152
2153 /*
2154 * If there is one non-busy active path at least, the path selector
2155 * will be able to select it. So we consider such a pg as not busy.
2156 */
2157 busy = true;
2158 list_for_each_entry(pgpath, &pg->pgpaths, list) {
2159 if (pgpath->is_active) {
2160 has_active = true;
2161 if (!pgpath_busy(pgpath)) {
2162 busy = false;
2163 break;
2164 }
2165 }
2166 }
2167
2168 if (!has_active) {
2169 /*
2170 * No active path in this pg, so this pg won't be used and
2171 * the current_pg will be changed at next mapping time.
2172 * We need to try mapping to determine it.
2173 */
2174 busy = false;
2175 }
2176
2177 return busy;
2178}
2179
2180/*
2181 *---------------------------------------------------------------
2182 * Module setup
2183 *---------------------------------------------------------------
2184 */
2185static struct target_type multipath_target = {
2186 .name = "multipath",
2187 .version = {1, 14, 0},
2188 .features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE |
2189 DM_TARGET_PASSES_INTEGRITY,
2190 .module = THIS_MODULE,
2191 .ctr = multipath_ctr,
2192 .dtr = multipath_dtr,
2193 .clone_and_map_rq = multipath_clone_and_map,
2194 .release_clone_rq = multipath_release_clone,
2195 .rq_end_io = multipath_end_io,
2196 .map = multipath_map_bio,
2197 .end_io = multipath_end_io_bio,
2198 .presuspend = multipath_presuspend,
2199 .postsuspend = multipath_postsuspend,
2200 .resume = multipath_resume,
2201 .status = multipath_status,
2202 .message = multipath_message,
2203 .prepare_ioctl = multipath_prepare_ioctl,
2204 .iterate_devices = multipath_iterate_devices,
2205 .busy = multipath_busy,
2206};
2207
2208static int __init dm_multipath_init(void)
2209{
2210 int r = -ENOMEM;
2211
2212 kmultipathd = alloc_workqueue("kmpathd", WQ_MEM_RECLAIM, 0);
2213 if (!kmultipathd) {
2214 DMERR("failed to create workqueue kmpathd");
2215 goto bad_alloc_kmultipathd;
2216 }
2217
2218 /*
2219 * A separate workqueue is used to handle the device handlers
2220 * to avoid overloading existing workqueue. Overloading the
2221 * old workqueue would also create a bottleneck in the
2222 * path of the storage hardware device activation.
2223 */
2224 kmpath_handlerd = alloc_ordered_workqueue("kmpath_handlerd",
2225 WQ_MEM_RECLAIM);
2226 if (!kmpath_handlerd) {
2227 DMERR("failed to create workqueue kmpath_handlerd");
2228 goto bad_alloc_kmpath_handlerd;
2229 }
2230
2231 dm_mpath_wq = alloc_workqueue("dm_mpath_wq", 0, 0);
2232 if (!dm_mpath_wq) {
2233 DMERR("failed to create workqueue dm_mpath_wq");
2234 goto bad_alloc_dm_mpath_wq;
2235 }
2236
2237 r = dm_register_target(&multipath_target);
2238 if (r < 0)
2239 goto bad_register_target;
2240
2241 return 0;
2242
2243bad_register_target:
2244 destroy_workqueue(dm_mpath_wq);
2245bad_alloc_dm_mpath_wq:
2246 destroy_workqueue(kmpath_handlerd);
2247bad_alloc_kmpath_handlerd:
2248 destroy_workqueue(kmultipathd);
2249bad_alloc_kmultipathd:
2250 return r;
2251}
2252
2253static void __exit dm_multipath_exit(void)
2254{
2255 destroy_workqueue(dm_mpath_wq);
2256 destroy_workqueue(kmpath_handlerd);
2257 destroy_workqueue(kmultipathd);
2258
2259 dm_unregister_target(&multipath_target);
2260}
2261
2262module_init(dm_multipath_init);
2263module_exit(dm_multipath_exit);
2264
2265module_param_named(queue_if_no_path_timeout_secs, queue_if_no_path_timeout_secs, ulong, 0644);
2266MODULE_PARM_DESC(queue_if_no_path_timeout_secs, "No available paths queue IO timeout in seconds");
2267
2268MODULE_DESCRIPTION(DM_NAME " multipath target");
2269MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
2270MODULE_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");