Merge branch 'kvm-arm64/pt-new' into kvmarm-master/next
[linux-2.6-microblaze.git] / drivers / md / dm-mpath.c
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-rq.h"
11 #include "dm-bio-record.h"
12 #include "dm-path-selector.h"
13 #include "dm-uevent.h"
14
15 #include <linux/blkdev.h>
16 #include <linux/ctype.h>
17 #include <linux/init.h>
18 #include <linux/mempool.h>
19 #include <linux/module.h>
20 #include <linux/pagemap.h>
21 #include <linux/slab.h>
22 #include <linux/time.h>
23 #include <linux/timer.h>
24 #include <linux/workqueue.h>
25 #include <linux/delay.h>
26 #include <scsi/scsi_dh.h>
27 #include <linux/atomic.h>
28 #include <linux/blk-mq.h>
29
30 #define DM_MSG_PREFIX "multipath"
31 #define DM_PG_INIT_DELAY_MSECS 2000
32 #define DM_PG_INIT_DELAY_DEFAULT ((unsigned) -1)
33 #define QUEUE_IF_NO_PATH_TIMEOUT_DEFAULT 0
34
35 static unsigned long queue_if_no_path_timeout_secs = QUEUE_IF_NO_PATH_TIMEOUT_DEFAULT;
36
37 /* Path properties */
38 struct pgpath {
39         struct list_head list;
40
41         struct priority_group *pg;      /* Owning PG */
42         unsigned fail_count;            /* Cumulative failure count */
43
44         struct dm_path path;
45         struct delayed_work activate_path;
46
47         bool is_active:1;               /* Path status */
48 };
49
50 #define path_to_pgpath(__pgp) container_of((__pgp), struct pgpath, path)
51
52 /*
53  * Paths are grouped into Priority Groups and numbered from 1 upwards.
54  * Each has a path selector which controls which path gets used.
55  */
56 struct priority_group {
57         struct list_head list;
58
59         struct multipath *m;            /* Owning multipath instance */
60         struct path_selector ps;
61
62         unsigned pg_num;                /* Reference number */
63         unsigned nr_pgpaths;            /* Number of paths in PG */
64         struct list_head pgpaths;
65
66         bool bypassed:1;                /* Temporarily bypass this PG? */
67 };
68
69 /* Multipath context */
70 struct multipath {
71         unsigned long flags;            /* Multipath state flags */
72
73         spinlock_t lock;
74         enum dm_queue_mode queue_mode;
75
76         struct pgpath *current_pgpath;
77         struct priority_group *current_pg;
78         struct priority_group *next_pg; /* Switch to this PG if set */
79
80         atomic_t nr_valid_paths;        /* Total number of usable paths */
81         unsigned nr_priority_groups;
82         struct list_head priority_groups;
83
84         const char *hw_handler_name;
85         char *hw_handler_params;
86         wait_queue_head_t pg_init_wait; /* Wait for pg_init completion */
87         unsigned pg_init_retries;       /* Number of times to retry pg_init */
88         unsigned pg_init_delay_msecs;   /* Number of msecs before pg_init retry */
89         atomic_t pg_init_in_progress;   /* Only one pg_init allowed at once */
90         atomic_t pg_init_count;         /* Number of times pg_init called */
91
92         struct mutex work_mutex;
93         struct work_struct trigger_event;
94         struct dm_target *ti;
95
96         struct work_struct process_queued_bios;
97         struct bio_list queued_bios;
98
99         struct timer_list nopath_timer; /* Timeout for queue_if_no_path */
100 };
101
102 /*
103  * Context information attached to each io we process.
104  */
105 struct dm_mpath_io {
106         struct pgpath *pgpath;
107         size_t nr_bytes;
108 };
109
110 typedef int (*action_fn) (struct pgpath *pgpath);
111
112 static struct workqueue_struct *kmultipathd, *kmpath_handlerd;
113 static void trigger_event(struct work_struct *work);
114 static void activate_or_offline_path(struct pgpath *pgpath);
115 static void activate_path_work(struct work_struct *work);
116 static void process_queued_bios(struct work_struct *work);
117 static void queue_if_no_path_timeout_work(struct timer_list *t);
118
119 /*-----------------------------------------------
120  * Multipath state flags.
121  *-----------------------------------------------*/
122
123 #define MPATHF_QUEUE_IO 0                       /* Must we queue all I/O? */
124 #define MPATHF_QUEUE_IF_NO_PATH 1               /* Queue I/O if last path fails? */
125 #define MPATHF_SAVED_QUEUE_IF_NO_PATH 2         /* Saved state during suspension */
126 #define MPATHF_RETAIN_ATTACHED_HW_HANDLER 3     /* If there's already a hw_handler present, don't change it. */
127 #define MPATHF_PG_INIT_DISABLED 4               /* pg_init is not currently allowed */
128 #define MPATHF_PG_INIT_REQUIRED 5               /* pg_init needs calling? */
129 #define MPATHF_PG_INIT_DELAY_RETRY 6            /* Delay pg_init retry? */
130
131 static bool mpath_double_check_test_bit(int MPATHF_bit, struct multipath *m)
132 {
133         bool r = test_bit(MPATHF_bit, &m->flags);
134
135         if (r) {
136                 unsigned long flags;
137                 spin_lock_irqsave(&m->lock, flags);
138                 r = test_bit(MPATHF_bit, &m->flags);
139                 spin_unlock_irqrestore(&m->lock, flags);
140         }
141
142         return r;
143 }
144
145 /*-----------------------------------------------
146  * Allocation routines
147  *-----------------------------------------------*/
148
149 static struct pgpath *alloc_pgpath(void)
150 {
151         struct pgpath *pgpath = kzalloc(sizeof(*pgpath), GFP_KERNEL);
152
153         if (!pgpath)
154                 return NULL;
155
156         pgpath->is_active = true;
157
158         return pgpath;
159 }
160
161 static void free_pgpath(struct pgpath *pgpath)
162 {
163         kfree(pgpath);
164 }
165
166 static struct priority_group *alloc_priority_group(void)
167 {
168         struct priority_group *pg;
169
170         pg = kzalloc(sizeof(*pg), GFP_KERNEL);
171
172         if (pg)
173                 INIT_LIST_HEAD(&pg->pgpaths);
174
175         return pg;
176 }
177
178 static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti)
179 {
180         struct pgpath *pgpath, *tmp;
181
182         list_for_each_entry_safe(pgpath, tmp, pgpaths, list) {
183                 list_del(&pgpath->list);
184                 dm_put_device(ti, pgpath->path.dev);
185                 free_pgpath(pgpath);
186         }
187 }
188
189 static void free_priority_group(struct priority_group *pg,
190                                 struct dm_target *ti)
191 {
192         struct path_selector *ps = &pg->ps;
193
194         if (ps->type) {
195                 ps->type->destroy(ps);
196                 dm_put_path_selector(ps->type);
197         }
198
199         free_pgpaths(&pg->pgpaths, ti);
200         kfree(pg);
201 }
202
203 static struct multipath *alloc_multipath(struct dm_target *ti)
204 {
205         struct multipath *m;
206
207         m = kzalloc(sizeof(*m), GFP_KERNEL);
208         if (m) {
209                 INIT_LIST_HEAD(&m->priority_groups);
210                 spin_lock_init(&m->lock);
211                 atomic_set(&m->nr_valid_paths, 0);
212                 INIT_WORK(&m->trigger_event, trigger_event);
213                 mutex_init(&m->work_mutex);
214
215                 m->queue_mode = DM_TYPE_NONE;
216
217                 m->ti = ti;
218                 ti->private = m;
219
220                 timer_setup(&m->nopath_timer, queue_if_no_path_timeout_work, 0);
221         }
222
223         return m;
224 }
225
226 static int alloc_multipath_stage2(struct dm_target *ti, struct multipath *m)
227 {
228         if (m->queue_mode == DM_TYPE_NONE) {
229                 m->queue_mode = DM_TYPE_REQUEST_BASED;
230         } else if (m->queue_mode == DM_TYPE_BIO_BASED) {
231                 INIT_WORK(&m->process_queued_bios, process_queued_bios);
232                 /*
233                  * bio-based doesn't support any direct scsi_dh management;
234                  * it just discovers if a scsi_dh is attached.
235                  */
236                 set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags);
237         }
238
239         dm_table_set_type(ti->table, m->queue_mode);
240
241         /*
242          * Init fields that are only used when a scsi_dh is attached
243          * - must do this unconditionally (really doesn't hurt non-SCSI uses)
244          */
245         set_bit(MPATHF_QUEUE_IO, &m->flags);
246         atomic_set(&m->pg_init_in_progress, 0);
247         atomic_set(&m->pg_init_count, 0);
248         m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT;
249         init_waitqueue_head(&m->pg_init_wait);
250
251         return 0;
252 }
253
254 static void free_multipath(struct multipath *m)
255 {
256         struct priority_group *pg, *tmp;
257
258         list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) {
259                 list_del(&pg->list);
260                 free_priority_group(pg, m->ti);
261         }
262
263         kfree(m->hw_handler_name);
264         kfree(m->hw_handler_params);
265         mutex_destroy(&m->work_mutex);
266         kfree(m);
267 }
268
269 static struct dm_mpath_io *get_mpio(union map_info *info)
270 {
271         return info->ptr;
272 }
273
274 static size_t multipath_per_bio_data_size(void)
275 {
276         return sizeof(struct dm_mpath_io) + sizeof(struct dm_bio_details);
277 }
278
279 static struct dm_mpath_io *get_mpio_from_bio(struct bio *bio)
280 {
281         return dm_per_bio_data(bio, multipath_per_bio_data_size());
282 }
283
284 static struct dm_bio_details *get_bio_details_from_mpio(struct dm_mpath_io *mpio)
285 {
286         /* dm_bio_details is immediately after the dm_mpath_io in bio's per-bio-data */
287         void *bio_details = mpio + 1;
288         return bio_details;
289 }
290
291 static void multipath_init_per_bio_data(struct bio *bio, struct dm_mpath_io **mpio_p)
292 {
293         struct dm_mpath_io *mpio = get_mpio_from_bio(bio);
294         struct dm_bio_details *bio_details = get_bio_details_from_mpio(mpio);
295
296         mpio->nr_bytes = bio->bi_iter.bi_size;
297         mpio->pgpath = NULL;
298         *mpio_p = mpio;
299
300         dm_bio_record(bio_details, bio);
301 }
302
303 /*-----------------------------------------------
304  * Path selection
305  *-----------------------------------------------*/
306
307 static int __pg_init_all_paths(struct multipath *m)
308 {
309         struct pgpath *pgpath;
310         unsigned long pg_init_delay = 0;
311
312         lockdep_assert_held(&m->lock);
313
314         if (atomic_read(&m->pg_init_in_progress) || test_bit(MPATHF_PG_INIT_DISABLED, &m->flags))
315                 return 0;
316
317         atomic_inc(&m->pg_init_count);
318         clear_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
319
320         /* Check here to reset pg_init_required */
321         if (!m->current_pg)
322                 return 0;
323
324         if (test_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags))
325                 pg_init_delay = msecs_to_jiffies(m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT ?
326                                                  m->pg_init_delay_msecs : DM_PG_INIT_DELAY_MSECS);
327         list_for_each_entry(pgpath, &m->current_pg->pgpaths, list) {
328                 /* Skip failed paths */
329                 if (!pgpath->is_active)
330                         continue;
331                 if (queue_delayed_work(kmpath_handlerd, &pgpath->activate_path,
332                                        pg_init_delay))
333                         atomic_inc(&m->pg_init_in_progress);
334         }
335         return atomic_read(&m->pg_init_in_progress);
336 }
337
338 static int pg_init_all_paths(struct multipath *m)
339 {
340         int ret;
341         unsigned long flags;
342
343         spin_lock_irqsave(&m->lock, flags);
344         ret = __pg_init_all_paths(m);
345         spin_unlock_irqrestore(&m->lock, flags);
346
347         return ret;
348 }
349
350 static void __switch_pg(struct multipath *m, struct priority_group *pg)
351 {
352         lockdep_assert_held(&m->lock);
353
354         m->current_pg = pg;
355
356         /* Must we initialise the PG first, and queue I/O till it's ready? */
357         if (m->hw_handler_name) {
358                 set_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
359                 set_bit(MPATHF_QUEUE_IO, &m->flags);
360         } else {
361                 clear_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
362                 clear_bit(MPATHF_QUEUE_IO, &m->flags);
363         }
364
365         atomic_set(&m->pg_init_count, 0);
366 }
367
368 static struct pgpath *choose_path_in_pg(struct multipath *m,
369                                         struct priority_group *pg,
370                                         size_t nr_bytes)
371 {
372         unsigned long flags;
373         struct dm_path *path;
374         struct pgpath *pgpath;
375
376         path = pg->ps.type->select_path(&pg->ps, nr_bytes);
377         if (!path)
378                 return ERR_PTR(-ENXIO);
379
380         pgpath = path_to_pgpath(path);
381
382         if (unlikely(READ_ONCE(m->current_pg) != pg)) {
383                 /* Only update current_pgpath if pg changed */
384                 spin_lock_irqsave(&m->lock, flags);
385                 m->current_pgpath = pgpath;
386                 __switch_pg(m, pg);
387                 spin_unlock_irqrestore(&m->lock, flags);
388         }
389
390         return pgpath;
391 }
392
393 static struct pgpath *choose_pgpath(struct multipath *m, size_t nr_bytes)
394 {
395         unsigned long flags;
396         struct priority_group *pg;
397         struct pgpath *pgpath;
398         unsigned bypassed = 1;
399
400         if (!atomic_read(&m->nr_valid_paths)) {
401                 spin_lock_irqsave(&m->lock, flags);
402                 clear_bit(MPATHF_QUEUE_IO, &m->flags);
403                 spin_unlock_irqrestore(&m->lock, flags);
404                 goto failed;
405         }
406
407         /* Were we instructed to switch PG? */
408         if (READ_ONCE(m->next_pg)) {
409                 spin_lock_irqsave(&m->lock, flags);
410                 pg = m->next_pg;
411                 if (!pg) {
412                         spin_unlock_irqrestore(&m->lock, flags);
413                         goto check_current_pg;
414                 }
415                 m->next_pg = NULL;
416                 spin_unlock_irqrestore(&m->lock, flags);
417                 pgpath = choose_path_in_pg(m, pg, nr_bytes);
418                 if (!IS_ERR_OR_NULL(pgpath))
419                         return pgpath;
420         }
421
422         /* Don't change PG until it has no remaining paths */
423 check_current_pg:
424         pg = READ_ONCE(m->current_pg);
425         if (pg) {
426                 pgpath = choose_path_in_pg(m, pg, nr_bytes);
427                 if (!IS_ERR_OR_NULL(pgpath))
428                         return pgpath;
429         }
430
431         /*
432          * Loop through priority groups until we find a valid path.
433          * First time we skip PGs marked 'bypassed'.
434          * Second time we only try the ones we skipped, but set
435          * pg_init_delay_retry so we do not hammer controllers.
436          */
437         do {
438                 list_for_each_entry(pg, &m->priority_groups, list) {
439                         if (pg->bypassed == !!bypassed)
440                                 continue;
441                         pgpath = choose_path_in_pg(m, pg, nr_bytes);
442                         if (!IS_ERR_OR_NULL(pgpath)) {
443                                 if (!bypassed) {
444                                         spin_lock_irqsave(&m->lock, flags);
445                                         set_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
446                                         spin_unlock_irqrestore(&m->lock, flags);
447                                 }
448                                 return pgpath;
449                         }
450                 }
451         } while (bypassed--);
452
453 failed:
454         spin_lock_irqsave(&m->lock, flags);
455         m->current_pgpath = NULL;
456         m->current_pg = NULL;
457         spin_unlock_irqrestore(&m->lock, flags);
458
459         return NULL;
460 }
461
462 /*
463  * dm_report_EIO() is a macro instead of a function to make pr_debug_ratelimited()
464  * report the function name and line number of the function from which
465  * it has been invoked.
466  */
467 #define dm_report_EIO(m)                                                \
468 do {                                                                    \
469         struct mapped_device *md = dm_table_get_md((m)->ti->table);     \
470                                                                         \
471         DMDEBUG_LIMIT("%s: returning EIO; QIFNP = %d; SQIFNP = %d; DNFS = %d", \
472                       dm_device_name(md),                               \
473                       test_bit(MPATHF_QUEUE_IF_NO_PATH, &(m)->flags),   \
474                       test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &(m)->flags), \
475                       dm_noflush_suspending((m)->ti));                  \
476 } while (0)
477
478 /*
479  * Check whether bios must be queued in the device-mapper core rather
480  * than here in the target.
481  */
482 static bool __must_push_back(struct multipath *m)
483 {
484         return dm_noflush_suspending(m->ti);
485 }
486
487 static bool must_push_back_rq(struct multipath *m)
488 {
489         unsigned long flags;
490         bool ret;
491
492         spin_lock_irqsave(&m->lock, flags);
493         ret = (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) || __must_push_back(m));
494         spin_unlock_irqrestore(&m->lock, flags);
495
496         return ret;
497 }
498
499 /*
500  * Map cloned requests (request-based multipath)
501  */
502 static int multipath_clone_and_map(struct dm_target *ti, struct request *rq,
503                                    union map_info *map_context,
504                                    struct request **__clone)
505 {
506         struct multipath *m = ti->private;
507         size_t nr_bytes = blk_rq_bytes(rq);
508         struct pgpath *pgpath;
509         struct block_device *bdev;
510         struct dm_mpath_io *mpio = get_mpio(map_context);
511         struct request_queue *q;
512         struct request *clone;
513
514         /* Do we need to select a new pgpath? */
515         pgpath = READ_ONCE(m->current_pgpath);
516         if (!pgpath || !mpath_double_check_test_bit(MPATHF_QUEUE_IO, m))
517                 pgpath = choose_pgpath(m, nr_bytes);
518
519         if (!pgpath) {
520                 if (must_push_back_rq(m))
521                         return DM_MAPIO_DELAY_REQUEUE;
522                 dm_report_EIO(m);       /* Failed */
523                 return DM_MAPIO_KILL;
524         } else if (mpath_double_check_test_bit(MPATHF_QUEUE_IO, m) ||
525                    mpath_double_check_test_bit(MPATHF_PG_INIT_REQUIRED, m)) {
526                 pg_init_all_paths(m);
527                 return DM_MAPIO_DELAY_REQUEUE;
528         }
529
530         mpio->pgpath = pgpath;
531         mpio->nr_bytes = nr_bytes;
532
533         bdev = pgpath->path.dev->bdev;
534         q = bdev_get_queue(bdev);
535         clone = blk_get_request(q, rq->cmd_flags | REQ_NOMERGE,
536                         BLK_MQ_REQ_NOWAIT);
537         if (IS_ERR(clone)) {
538                 /* EBUSY, ENODEV or EWOULDBLOCK: requeue */
539                 if (blk_queue_dying(q)) {
540                         atomic_inc(&m->pg_init_in_progress);
541                         activate_or_offline_path(pgpath);
542                         return DM_MAPIO_DELAY_REQUEUE;
543                 }
544
545                 /*
546                  * blk-mq's SCHED_RESTART can cover this requeue, so we
547                  * needn't deal with it by DELAY_REQUEUE. More importantly,
548                  * we have to return DM_MAPIO_REQUEUE so that blk-mq can
549                  * get the queue busy feedback (via BLK_STS_RESOURCE),
550                  * otherwise I/O merging can suffer.
551                  */
552                 return DM_MAPIO_REQUEUE;
553         }
554         clone->bio = clone->biotail = NULL;
555         clone->rq_disk = bdev->bd_disk;
556         clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
557         *__clone = clone;
558
559         if (pgpath->pg->ps.type->start_io)
560                 pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
561                                               &pgpath->path,
562                                               nr_bytes);
563         return DM_MAPIO_REMAPPED;
564 }
565
566 static void multipath_release_clone(struct request *clone,
567                                     union map_info *map_context)
568 {
569         if (unlikely(map_context)) {
570                 /*
571                  * non-NULL map_context means caller is still map
572                  * method; must undo multipath_clone_and_map()
573                  */
574                 struct dm_mpath_io *mpio = get_mpio(map_context);
575                 struct pgpath *pgpath = mpio->pgpath;
576
577                 if (pgpath && pgpath->pg->ps.type->end_io)
578                         pgpath->pg->ps.type->end_io(&pgpath->pg->ps,
579                                                     &pgpath->path,
580                                                     mpio->nr_bytes,
581                                                     clone->io_start_time_ns);
582         }
583
584         blk_put_request(clone);
585 }
586
587 /*
588  * Map cloned bios (bio-based multipath)
589  */
590
591 static void __multipath_queue_bio(struct multipath *m, struct bio *bio)
592 {
593         /* Queue for the daemon to resubmit */
594         bio_list_add(&m->queued_bios, bio);
595         if (!test_bit(MPATHF_QUEUE_IO, &m->flags))
596                 queue_work(kmultipathd, &m->process_queued_bios);
597 }
598
599 static void multipath_queue_bio(struct multipath *m, struct bio *bio)
600 {
601         unsigned long flags;
602
603         spin_lock_irqsave(&m->lock, flags);
604         __multipath_queue_bio(m, bio);
605         spin_unlock_irqrestore(&m->lock, flags);
606 }
607
608 static struct pgpath *__map_bio(struct multipath *m, struct bio *bio)
609 {
610         struct pgpath *pgpath;
611         unsigned long flags;
612
613         /* Do we need to select a new pgpath? */
614         pgpath = READ_ONCE(m->current_pgpath);
615         if (!pgpath || !mpath_double_check_test_bit(MPATHF_QUEUE_IO, m))
616                 pgpath = choose_pgpath(m, bio->bi_iter.bi_size);
617
618         if (!pgpath) {
619                 spin_lock_irqsave(&m->lock, flags);
620                 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
621                         __multipath_queue_bio(m, bio);
622                         pgpath = ERR_PTR(-EAGAIN);
623                 }
624                 spin_unlock_irqrestore(&m->lock, flags);
625
626         } else if (mpath_double_check_test_bit(MPATHF_QUEUE_IO, m) ||
627                    mpath_double_check_test_bit(MPATHF_PG_INIT_REQUIRED, m)) {
628                 multipath_queue_bio(m, bio);
629                 pg_init_all_paths(m);
630                 return ERR_PTR(-EAGAIN);
631         }
632
633         return pgpath;
634 }
635
636 static int __multipath_map_bio(struct multipath *m, struct bio *bio,
637                                struct dm_mpath_io *mpio)
638 {
639         struct pgpath *pgpath = __map_bio(m, bio);
640
641         if (IS_ERR(pgpath))
642                 return DM_MAPIO_SUBMITTED;
643
644         if (!pgpath) {
645                 if (__must_push_back(m))
646                         return DM_MAPIO_REQUEUE;
647                 dm_report_EIO(m);
648                 return DM_MAPIO_KILL;
649         }
650
651         mpio->pgpath = pgpath;
652
653         bio->bi_status = 0;
654         bio_set_dev(bio, pgpath->path.dev->bdev);
655         bio->bi_opf |= REQ_FAILFAST_TRANSPORT;
656
657         if (pgpath->pg->ps.type->start_io)
658                 pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
659                                               &pgpath->path,
660                                               mpio->nr_bytes);
661         return DM_MAPIO_REMAPPED;
662 }
663
664 static int multipath_map_bio(struct dm_target *ti, struct bio *bio)
665 {
666         struct multipath *m = ti->private;
667         struct dm_mpath_io *mpio = NULL;
668
669         multipath_init_per_bio_data(bio, &mpio);
670         return __multipath_map_bio(m, bio, mpio);
671 }
672
673 static void process_queued_io_list(struct multipath *m)
674 {
675         if (m->queue_mode == DM_TYPE_REQUEST_BASED)
676                 dm_mq_kick_requeue_list(dm_table_get_md(m->ti->table));
677         else if (m->queue_mode == DM_TYPE_BIO_BASED)
678                 queue_work(kmultipathd, &m->process_queued_bios);
679 }
680
681 static void process_queued_bios(struct work_struct *work)
682 {
683         int r;
684         unsigned long flags;
685         struct bio *bio;
686         struct bio_list bios;
687         struct blk_plug plug;
688         struct multipath *m =
689                 container_of(work, struct multipath, process_queued_bios);
690
691         bio_list_init(&bios);
692
693         spin_lock_irqsave(&m->lock, flags);
694
695         if (bio_list_empty(&m->queued_bios)) {
696                 spin_unlock_irqrestore(&m->lock, flags);
697                 return;
698         }
699
700         bio_list_merge(&bios, &m->queued_bios);
701         bio_list_init(&m->queued_bios);
702
703         spin_unlock_irqrestore(&m->lock, flags);
704
705         blk_start_plug(&plug);
706         while ((bio = bio_list_pop(&bios))) {
707                 struct dm_mpath_io *mpio = get_mpio_from_bio(bio);
708                 dm_bio_restore(get_bio_details_from_mpio(mpio), bio);
709                 r = __multipath_map_bio(m, bio, mpio);
710                 switch (r) {
711                 case DM_MAPIO_KILL:
712                         bio->bi_status = BLK_STS_IOERR;
713                         bio_endio(bio);
714                         break;
715                 case DM_MAPIO_REQUEUE:
716                         bio->bi_status = BLK_STS_DM_REQUEUE;
717                         bio_endio(bio);
718                         break;
719                 case DM_MAPIO_REMAPPED:
720                         submit_bio_noacct(bio);
721                         break;
722                 case DM_MAPIO_SUBMITTED:
723                         break;
724                 default:
725                         WARN_ONCE(true, "__multipath_map_bio() returned %d\n", r);
726                 }
727         }
728         blk_finish_plug(&plug);
729 }
730
731 /*
732  * If we run out of usable paths, should we queue I/O or error it?
733  */
734 static int queue_if_no_path(struct multipath *m, bool queue_if_no_path,
735                             bool save_old_value, const char *caller)
736 {
737         unsigned long flags;
738         bool queue_if_no_path_bit, saved_queue_if_no_path_bit;
739         const char *dm_dev_name = dm_device_name(dm_table_get_md(m->ti->table));
740
741         DMDEBUG("%s: %s caller=%s queue_if_no_path=%d save_old_value=%d",
742                 dm_dev_name, __func__, caller, queue_if_no_path, save_old_value);
743
744         spin_lock_irqsave(&m->lock, flags);
745
746         queue_if_no_path_bit = test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
747         saved_queue_if_no_path_bit = test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
748
749         if (save_old_value) {
750                 if (unlikely(!queue_if_no_path_bit && saved_queue_if_no_path_bit)) {
751                         DMERR("%s: QIFNP disabled but saved as enabled, saving again loses state, not saving!",
752                               dm_dev_name);
753                 } else
754                         assign_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags, queue_if_no_path_bit);
755         } else if (!queue_if_no_path && saved_queue_if_no_path_bit) {
756                 /* due to "fail_if_no_path" message, need to honor it. */
757                 clear_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
758         }
759         assign_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags, queue_if_no_path);
760
761         DMDEBUG("%s: after %s changes; QIFNP = %d; SQIFNP = %d; DNFS = %d",
762                 dm_dev_name, __func__,
763                 test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags),
764                 test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags),
765                 dm_noflush_suspending(m->ti));
766
767         spin_unlock_irqrestore(&m->lock, flags);
768
769         if (!queue_if_no_path) {
770                 dm_table_run_md_queue_async(m->ti->table);
771                 process_queued_io_list(m);
772         }
773
774         return 0;
775 }
776
777 /*
778  * If the queue_if_no_path timeout fires, turn off queue_if_no_path and
779  * process any queued I/O.
780  */
781 static void queue_if_no_path_timeout_work(struct timer_list *t)
782 {
783         struct multipath *m = from_timer(m, t, nopath_timer);
784         struct mapped_device *md = dm_table_get_md(m->ti->table);
785
786         DMWARN("queue_if_no_path timeout on %s, failing queued IO", dm_device_name(md));
787         queue_if_no_path(m, false, false, __func__);
788 }
789
790 /*
791  * Enable the queue_if_no_path timeout if necessary.
792  * Called with m->lock held.
793  */
794 static void enable_nopath_timeout(struct multipath *m)
795 {
796         unsigned long queue_if_no_path_timeout =
797                 READ_ONCE(queue_if_no_path_timeout_secs) * HZ;
798
799         lockdep_assert_held(&m->lock);
800
801         if (queue_if_no_path_timeout > 0 &&
802             atomic_read(&m->nr_valid_paths) == 0 &&
803             test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
804                 mod_timer(&m->nopath_timer,
805                           jiffies + queue_if_no_path_timeout);
806         }
807 }
808
809 static void disable_nopath_timeout(struct multipath *m)
810 {
811         del_timer_sync(&m->nopath_timer);
812 }
813
814 /*
815  * An event is triggered whenever a path is taken out of use.
816  * Includes path failure and PG bypass.
817  */
818 static void trigger_event(struct work_struct *work)
819 {
820         struct multipath *m =
821                 container_of(work, struct multipath, trigger_event);
822
823         dm_table_event(m->ti->table);
824 }
825
826 /*-----------------------------------------------------------------
827  * Constructor/argument parsing:
828  * <#multipath feature args> [<arg>]*
829  * <#hw_handler args> [hw_handler [<arg>]*]
830  * <#priority groups>
831  * <initial priority group>
832  *     [<selector> <#selector args> [<arg>]*
833  *      <#paths> <#per-path selector args>
834  *         [<path> [<arg>]* ]+ ]+
835  *---------------------------------------------------------------*/
836 static int parse_path_selector(struct dm_arg_set *as, struct priority_group *pg,
837                                struct dm_target *ti)
838 {
839         int r;
840         struct path_selector_type *pst;
841         unsigned ps_argc;
842
843         static const struct dm_arg _args[] = {
844                 {0, 1024, "invalid number of path selector args"},
845         };
846
847         pst = dm_get_path_selector(dm_shift_arg(as));
848         if (!pst) {
849                 ti->error = "unknown path selector type";
850                 return -EINVAL;
851         }
852
853         r = dm_read_arg_group(_args, as, &ps_argc, &ti->error);
854         if (r) {
855                 dm_put_path_selector(pst);
856                 return -EINVAL;
857         }
858
859         r = pst->create(&pg->ps, ps_argc, as->argv);
860         if (r) {
861                 dm_put_path_selector(pst);
862                 ti->error = "path selector constructor failed";
863                 return r;
864         }
865
866         pg->ps.type = pst;
867         dm_consume_args(as, ps_argc);
868
869         return 0;
870 }
871
872 static int setup_scsi_dh(struct block_device *bdev, struct multipath *m,
873                          const char **attached_handler_name, char **error)
874 {
875         struct request_queue *q = bdev_get_queue(bdev);
876         int r;
877
878         if (mpath_double_check_test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, m)) {
879 retain:
880                 if (*attached_handler_name) {
881                         /*
882                          * Clear any hw_handler_params associated with a
883                          * handler that isn't already attached.
884                          */
885                         if (m->hw_handler_name && strcmp(*attached_handler_name, m->hw_handler_name)) {
886                                 kfree(m->hw_handler_params);
887                                 m->hw_handler_params = NULL;
888                         }
889
890                         /*
891                          * Reset hw_handler_name to match the attached handler
892                          *
893                          * NB. This modifies the table line to show the actual
894                          * handler instead of the original table passed in.
895                          */
896                         kfree(m->hw_handler_name);
897                         m->hw_handler_name = *attached_handler_name;
898                         *attached_handler_name = NULL;
899                 }
900         }
901
902         if (m->hw_handler_name) {
903                 r = scsi_dh_attach(q, m->hw_handler_name);
904                 if (r == -EBUSY) {
905                         char b[BDEVNAME_SIZE];
906
907                         printk(KERN_INFO "dm-mpath: retaining handler on device %s\n",
908                                bdevname(bdev, b));
909                         goto retain;
910                 }
911                 if (r < 0) {
912                         *error = "error attaching hardware handler";
913                         return r;
914                 }
915
916                 if (m->hw_handler_params) {
917                         r = scsi_dh_set_params(q, m->hw_handler_params);
918                         if (r < 0) {
919                                 *error = "unable to set hardware handler parameters";
920                                 return r;
921                         }
922                 }
923         }
924
925         return 0;
926 }
927
928 static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps,
929                                  struct dm_target *ti)
930 {
931         int r;
932         struct pgpath *p;
933         struct multipath *m = ti->private;
934         struct request_queue *q;
935         const char *attached_handler_name = NULL;
936
937         /* we need at least a path arg */
938         if (as->argc < 1) {
939                 ti->error = "no device given";
940                 return ERR_PTR(-EINVAL);
941         }
942
943         p = alloc_pgpath();
944         if (!p)
945                 return ERR_PTR(-ENOMEM);
946
947         r = dm_get_device(ti, dm_shift_arg(as), dm_table_get_mode(ti->table),
948                           &p->path.dev);
949         if (r) {
950                 ti->error = "error getting device";
951                 goto bad;
952         }
953
954         q = bdev_get_queue(p->path.dev->bdev);
955         attached_handler_name = scsi_dh_attached_handler_name(q, GFP_KERNEL);
956         if (attached_handler_name || m->hw_handler_name) {
957                 INIT_DELAYED_WORK(&p->activate_path, activate_path_work);
958                 r = setup_scsi_dh(p->path.dev->bdev, m, &attached_handler_name, &ti->error);
959                 kfree(attached_handler_name);
960                 if (r) {
961                         dm_put_device(ti, p->path.dev);
962                         goto bad;
963                 }
964         }
965
966         r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
967         if (r) {
968                 dm_put_device(ti, p->path.dev);
969                 goto bad;
970         }
971
972         return p;
973  bad:
974         free_pgpath(p);
975         return ERR_PTR(r);
976 }
977
978 static struct priority_group *parse_priority_group(struct dm_arg_set *as,
979                                                    struct multipath *m)
980 {
981         static const struct dm_arg _args[] = {
982                 {1, 1024, "invalid number of paths"},
983                 {0, 1024, "invalid number of selector args"}
984         };
985
986         int r;
987         unsigned i, nr_selector_args, nr_args;
988         struct priority_group *pg;
989         struct dm_target *ti = m->ti;
990
991         if (as->argc < 2) {
992                 as->argc = 0;
993                 ti->error = "not enough priority group arguments";
994                 return ERR_PTR(-EINVAL);
995         }
996
997         pg = alloc_priority_group();
998         if (!pg) {
999                 ti->error = "couldn't allocate priority group";
1000                 return ERR_PTR(-ENOMEM);
1001         }
1002         pg->m = m;
1003
1004         r = parse_path_selector(as, pg, ti);
1005         if (r)
1006                 goto bad;
1007
1008         /*
1009          * read the paths
1010          */
1011         r = dm_read_arg(_args, as, &pg->nr_pgpaths, &ti->error);
1012         if (r)
1013                 goto bad;
1014
1015         r = dm_read_arg(_args + 1, as, &nr_selector_args, &ti->error);
1016         if (r)
1017                 goto bad;
1018
1019         nr_args = 1 + nr_selector_args;
1020         for (i = 0; i < pg->nr_pgpaths; i++) {
1021                 struct pgpath *pgpath;
1022                 struct dm_arg_set path_args;
1023
1024                 if (as->argc < nr_args) {
1025                         ti->error = "not enough path parameters";
1026                         r = -EINVAL;
1027                         goto bad;
1028                 }
1029
1030                 path_args.argc = nr_args;
1031                 path_args.argv = as->argv;
1032
1033                 pgpath = parse_path(&path_args, &pg->ps, ti);
1034                 if (IS_ERR(pgpath)) {
1035                         r = PTR_ERR(pgpath);
1036                         goto bad;
1037                 }
1038
1039                 pgpath->pg = pg;
1040                 list_add_tail(&pgpath->list, &pg->pgpaths);
1041                 dm_consume_args(as, nr_args);
1042         }
1043
1044         return pg;
1045
1046  bad:
1047         free_priority_group(pg, ti);
1048         return ERR_PTR(r);
1049 }
1050
1051 static int parse_hw_handler(struct dm_arg_set *as, struct multipath *m)
1052 {
1053         unsigned hw_argc;
1054         int ret;
1055         struct dm_target *ti = m->ti;
1056
1057         static const struct dm_arg _args[] = {
1058                 {0, 1024, "invalid number of hardware handler args"},
1059         };
1060
1061         if (dm_read_arg_group(_args, as, &hw_argc, &ti->error))
1062                 return -EINVAL;
1063
1064         if (!hw_argc)
1065                 return 0;
1066
1067         if (m->queue_mode == DM_TYPE_BIO_BASED) {
1068                 dm_consume_args(as, hw_argc);
1069                 DMERR("bio-based multipath doesn't allow hardware handler args");
1070                 return 0;
1071         }
1072
1073         m->hw_handler_name = kstrdup(dm_shift_arg(as), GFP_KERNEL);
1074         if (!m->hw_handler_name)
1075                 return -EINVAL;
1076
1077         if (hw_argc > 1) {
1078                 char *p;
1079                 int i, j, len = 4;
1080
1081                 for (i = 0; i <= hw_argc - 2; i++)
1082                         len += strlen(as->argv[i]) + 1;
1083                 p = m->hw_handler_params = kzalloc(len, GFP_KERNEL);
1084                 if (!p) {
1085                         ti->error = "memory allocation failed";
1086                         ret = -ENOMEM;
1087                         goto fail;
1088                 }
1089                 j = sprintf(p, "%d", hw_argc - 1);
1090                 for (i = 0, p+=j+1; i <= hw_argc - 2; i++, p+=j+1)
1091                         j = sprintf(p, "%s", as->argv[i]);
1092         }
1093         dm_consume_args(as, hw_argc - 1);
1094
1095         return 0;
1096 fail:
1097         kfree(m->hw_handler_name);
1098         m->hw_handler_name = NULL;
1099         return ret;
1100 }
1101
1102 static int parse_features(struct dm_arg_set *as, struct multipath *m)
1103 {
1104         int r;
1105         unsigned argc;
1106         struct dm_target *ti = m->ti;
1107         const char *arg_name;
1108
1109         static const struct dm_arg _args[] = {
1110                 {0, 8, "invalid number of feature args"},
1111                 {1, 50, "pg_init_retries must be between 1 and 50"},
1112                 {0, 60000, "pg_init_delay_msecs must be between 0 and 60000"},
1113         };
1114
1115         r = dm_read_arg_group(_args, as, &argc, &ti->error);
1116         if (r)
1117                 return -EINVAL;
1118
1119         if (!argc)
1120                 return 0;
1121
1122         do {
1123                 arg_name = dm_shift_arg(as);
1124                 argc--;
1125
1126                 if (!strcasecmp(arg_name, "queue_if_no_path")) {
1127                         r = queue_if_no_path(m, true, false, __func__);
1128                         continue;
1129                 }
1130
1131                 if (!strcasecmp(arg_name, "retain_attached_hw_handler")) {
1132                         set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags);
1133                         continue;
1134                 }
1135
1136                 if (!strcasecmp(arg_name, "pg_init_retries") &&
1137                     (argc >= 1)) {
1138                         r = dm_read_arg(_args + 1, as, &m->pg_init_retries, &ti->error);
1139                         argc--;
1140                         continue;
1141                 }
1142
1143                 if (!strcasecmp(arg_name, "pg_init_delay_msecs") &&
1144                     (argc >= 1)) {
1145                         r = dm_read_arg(_args + 2, as, &m->pg_init_delay_msecs, &ti->error);
1146                         argc--;
1147                         continue;
1148                 }
1149
1150                 if (!strcasecmp(arg_name, "queue_mode") &&
1151                     (argc >= 1)) {
1152                         const char *queue_mode_name = dm_shift_arg(as);
1153
1154                         if (!strcasecmp(queue_mode_name, "bio"))
1155                                 m->queue_mode = DM_TYPE_BIO_BASED;
1156                         else if (!strcasecmp(queue_mode_name, "rq") ||
1157                                  !strcasecmp(queue_mode_name, "mq"))
1158                                 m->queue_mode = DM_TYPE_REQUEST_BASED;
1159                         else {
1160                                 ti->error = "Unknown 'queue_mode' requested";
1161                                 r = -EINVAL;
1162                         }
1163                         argc--;
1164                         continue;
1165                 }
1166
1167                 ti->error = "Unrecognised multipath feature request";
1168                 r = -EINVAL;
1169         } while (argc && !r);
1170
1171         return r;
1172 }
1173
1174 static int multipath_ctr(struct dm_target *ti, unsigned argc, char **argv)
1175 {
1176         /* target arguments */
1177         static const struct dm_arg _args[] = {
1178                 {0, 1024, "invalid number of priority groups"},
1179                 {0, 1024, "invalid initial priority group number"},
1180         };
1181
1182         int r;
1183         struct multipath *m;
1184         struct dm_arg_set as;
1185         unsigned pg_count = 0;
1186         unsigned next_pg_num;
1187         unsigned long flags;
1188
1189         as.argc = argc;
1190         as.argv = argv;
1191
1192         m = alloc_multipath(ti);
1193         if (!m) {
1194                 ti->error = "can't allocate multipath";
1195                 return -EINVAL;
1196         }
1197
1198         r = parse_features(&as, m);
1199         if (r)
1200                 goto bad;
1201
1202         r = alloc_multipath_stage2(ti, m);
1203         if (r)
1204                 goto bad;
1205
1206         r = parse_hw_handler(&as, m);
1207         if (r)
1208                 goto bad;
1209
1210         r = dm_read_arg(_args, &as, &m->nr_priority_groups, &ti->error);
1211         if (r)
1212                 goto bad;
1213
1214         r = dm_read_arg(_args + 1, &as, &next_pg_num, &ti->error);
1215         if (r)
1216                 goto bad;
1217
1218         if ((!m->nr_priority_groups && next_pg_num) ||
1219             (m->nr_priority_groups && !next_pg_num)) {
1220                 ti->error = "invalid initial priority group";
1221                 r = -EINVAL;
1222                 goto bad;
1223         }
1224
1225         /* parse the priority groups */
1226         while (as.argc) {
1227                 struct priority_group *pg;
1228                 unsigned nr_valid_paths = atomic_read(&m->nr_valid_paths);
1229
1230                 pg = parse_priority_group(&as, m);
1231                 if (IS_ERR(pg)) {
1232                         r = PTR_ERR(pg);
1233                         goto bad;
1234                 }
1235
1236                 nr_valid_paths += pg->nr_pgpaths;
1237                 atomic_set(&m->nr_valid_paths, nr_valid_paths);
1238
1239                 list_add_tail(&pg->list, &m->priority_groups);
1240                 pg_count++;
1241                 pg->pg_num = pg_count;
1242                 if (!--next_pg_num)
1243                         m->next_pg = pg;
1244         }
1245
1246         if (pg_count != m->nr_priority_groups) {
1247                 ti->error = "priority group count mismatch";
1248                 r = -EINVAL;
1249                 goto bad;
1250         }
1251
1252         spin_lock_irqsave(&m->lock, flags);
1253         enable_nopath_timeout(m);
1254         spin_unlock_irqrestore(&m->lock, flags);
1255
1256         ti->num_flush_bios = 1;
1257         ti->num_discard_bios = 1;
1258         ti->num_write_same_bios = 1;
1259         ti->num_write_zeroes_bios = 1;
1260         if (m->queue_mode == DM_TYPE_BIO_BASED)
1261                 ti->per_io_data_size = multipath_per_bio_data_size();
1262         else
1263                 ti->per_io_data_size = sizeof(struct dm_mpath_io);
1264
1265         return 0;
1266
1267  bad:
1268         free_multipath(m);
1269         return r;
1270 }
1271
1272 static void multipath_wait_for_pg_init_completion(struct multipath *m)
1273 {
1274         DEFINE_WAIT(wait);
1275
1276         while (1) {
1277                 prepare_to_wait(&m->pg_init_wait, &wait, TASK_UNINTERRUPTIBLE);
1278
1279                 if (!atomic_read(&m->pg_init_in_progress))
1280                         break;
1281
1282                 io_schedule();
1283         }
1284         finish_wait(&m->pg_init_wait, &wait);
1285 }
1286
1287 static void flush_multipath_work(struct multipath *m)
1288 {
1289         if (m->hw_handler_name) {
1290                 unsigned long flags;
1291
1292                 if (!atomic_read(&m->pg_init_in_progress))
1293                         goto skip;
1294
1295                 spin_lock_irqsave(&m->lock, flags);
1296                 if (atomic_read(&m->pg_init_in_progress) &&
1297                     !test_and_set_bit(MPATHF_PG_INIT_DISABLED, &m->flags)) {
1298                         spin_unlock_irqrestore(&m->lock, flags);
1299
1300                         flush_workqueue(kmpath_handlerd);
1301                         multipath_wait_for_pg_init_completion(m);
1302
1303                         spin_lock_irqsave(&m->lock, flags);
1304                         clear_bit(MPATHF_PG_INIT_DISABLED, &m->flags);
1305                 }
1306                 spin_unlock_irqrestore(&m->lock, flags);
1307         }
1308 skip:
1309         if (m->queue_mode == DM_TYPE_BIO_BASED)
1310                 flush_work(&m->process_queued_bios);
1311         flush_work(&m->trigger_event);
1312 }
1313
1314 static void multipath_dtr(struct dm_target *ti)
1315 {
1316         struct multipath *m = ti->private;
1317
1318         disable_nopath_timeout(m);
1319         flush_multipath_work(m);
1320         free_multipath(m);
1321 }
1322
1323 /*
1324  * Take a path out of use.
1325  */
1326 static int fail_path(struct pgpath *pgpath)
1327 {
1328         unsigned long flags;
1329         struct multipath *m = pgpath->pg->m;
1330
1331         spin_lock_irqsave(&m->lock, flags);
1332
1333         if (!pgpath->is_active)
1334                 goto out;
1335
1336         DMWARN("%s: Failing path %s.",
1337                dm_device_name(dm_table_get_md(m->ti->table)),
1338                pgpath->path.dev->name);
1339
1340         pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
1341         pgpath->is_active = false;
1342         pgpath->fail_count++;
1343
1344         atomic_dec(&m->nr_valid_paths);
1345
1346         if (pgpath == m->current_pgpath)
1347                 m->current_pgpath = NULL;
1348
1349         dm_path_uevent(DM_UEVENT_PATH_FAILED, m->ti,
1350                        pgpath->path.dev->name, atomic_read(&m->nr_valid_paths));
1351
1352         schedule_work(&m->trigger_event);
1353
1354         enable_nopath_timeout(m);
1355
1356 out:
1357         spin_unlock_irqrestore(&m->lock, flags);
1358
1359         return 0;
1360 }
1361
1362 /*
1363  * Reinstate a previously-failed path
1364  */
1365 static int reinstate_path(struct pgpath *pgpath)
1366 {
1367         int r = 0, run_queue = 0;
1368         unsigned long flags;
1369         struct multipath *m = pgpath->pg->m;
1370         unsigned nr_valid_paths;
1371
1372         spin_lock_irqsave(&m->lock, flags);
1373
1374         if (pgpath->is_active)
1375                 goto out;
1376
1377         DMWARN("%s: Reinstating path %s.",
1378                dm_device_name(dm_table_get_md(m->ti->table)),
1379                pgpath->path.dev->name);
1380
1381         r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
1382         if (r)
1383                 goto out;
1384
1385         pgpath->is_active = true;
1386
1387         nr_valid_paths = atomic_inc_return(&m->nr_valid_paths);
1388         if (nr_valid_paths == 1) {
1389                 m->current_pgpath = NULL;
1390                 run_queue = 1;
1391         } else if (m->hw_handler_name && (m->current_pg == pgpath->pg)) {
1392                 if (queue_work(kmpath_handlerd, &pgpath->activate_path.work))
1393                         atomic_inc(&m->pg_init_in_progress);
1394         }
1395
1396         dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti,
1397                        pgpath->path.dev->name, nr_valid_paths);
1398
1399         schedule_work(&m->trigger_event);
1400
1401 out:
1402         spin_unlock_irqrestore(&m->lock, flags);
1403         if (run_queue) {
1404                 dm_table_run_md_queue_async(m->ti->table);
1405                 process_queued_io_list(m);
1406         }
1407
1408         if (pgpath->is_active)
1409                 disable_nopath_timeout(m);
1410
1411         return r;
1412 }
1413
1414 /*
1415  * Fail or reinstate all paths that match the provided struct dm_dev.
1416  */
1417 static int action_dev(struct multipath *m, struct dm_dev *dev,
1418                       action_fn action)
1419 {
1420         int r = -EINVAL;
1421         struct pgpath *pgpath;
1422         struct priority_group *pg;
1423
1424         list_for_each_entry(pg, &m->priority_groups, list) {
1425                 list_for_each_entry(pgpath, &pg->pgpaths, list) {
1426                         if (pgpath->path.dev == dev)
1427                                 r = action(pgpath);
1428                 }
1429         }
1430
1431         return r;
1432 }
1433
1434 /*
1435  * Temporarily try to avoid having to use the specified PG
1436  */
1437 static void bypass_pg(struct multipath *m, struct priority_group *pg,
1438                       bool bypassed)
1439 {
1440         unsigned long flags;
1441
1442         spin_lock_irqsave(&m->lock, flags);
1443
1444         pg->bypassed = bypassed;
1445         m->current_pgpath = NULL;
1446         m->current_pg = NULL;
1447
1448         spin_unlock_irqrestore(&m->lock, flags);
1449
1450         schedule_work(&m->trigger_event);
1451 }
1452
1453 /*
1454  * Switch to using the specified PG from the next I/O that gets mapped
1455  */
1456 static int switch_pg_num(struct multipath *m, const char *pgstr)
1457 {
1458         struct priority_group *pg;
1459         unsigned pgnum;
1460         unsigned long flags;
1461         char dummy;
1462
1463         if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1464             !m->nr_priority_groups || (pgnum > m->nr_priority_groups)) {
1465                 DMWARN("invalid PG number supplied to switch_pg_num");
1466                 return -EINVAL;
1467         }
1468
1469         spin_lock_irqsave(&m->lock, flags);
1470         list_for_each_entry(pg, &m->priority_groups, list) {
1471                 pg->bypassed = false;
1472                 if (--pgnum)
1473                         continue;
1474
1475                 m->current_pgpath = NULL;
1476                 m->current_pg = NULL;
1477                 m->next_pg = pg;
1478         }
1479         spin_unlock_irqrestore(&m->lock, flags);
1480
1481         schedule_work(&m->trigger_event);
1482         return 0;
1483 }
1484
1485 /*
1486  * Set/clear bypassed status of a PG.
1487  * PGs are numbered upwards from 1 in the order they were declared.
1488  */
1489 static int bypass_pg_num(struct multipath *m, const char *pgstr, bool bypassed)
1490 {
1491         struct priority_group *pg;
1492         unsigned pgnum;
1493         char dummy;
1494
1495         if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1496             !m->nr_priority_groups || (pgnum > m->nr_priority_groups)) {
1497                 DMWARN("invalid PG number supplied to bypass_pg");
1498                 return -EINVAL;
1499         }
1500
1501         list_for_each_entry(pg, &m->priority_groups, list) {
1502                 if (!--pgnum)
1503                         break;
1504         }
1505
1506         bypass_pg(m, pg, bypassed);
1507         return 0;
1508 }
1509
1510 /*
1511  * Should we retry pg_init immediately?
1512  */
1513 static bool pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath)
1514 {
1515         unsigned long flags;
1516         bool limit_reached = false;
1517
1518         spin_lock_irqsave(&m->lock, flags);
1519
1520         if (atomic_read(&m->pg_init_count) <= m->pg_init_retries &&
1521             !test_bit(MPATHF_PG_INIT_DISABLED, &m->flags))
1522                 set_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
1523         else
1524                 limit_reached = true;
1525
1526         spin_unlock_irqrestore(&m->lock, flags);
1527
1528         return limit_reached;
1529 }
1530
1531 static void pg_init_done(void *data, int errors)
1532 {
1533         struct pgpath *pgpath = data;
1534         struct priority_group *pg = pgpath->pg;
1535         struct multipath *m = pg->m;
1536         unsigned long flags;
1537         bool delay_retry = false;
1538
1539         /* device or driver problems */
1540         switch (errors) {
1541         case SCSI_DH_OK:
1542                 break;
1543         case SCSI_DH_NOSYS:
1544                 if (!m->hw_handler_name) {
1545                         errors = 0;
1546                         break;
1547                 }
1548                 DMERR("Could not failover the device: Handler scsi_dh_%s "
1549                       "Error %d.", m->hw_handler_name, errors);
1550                 /*
1551                  * Fail path for now, so we do not ping pong
1552                  */
1553                 fail_path(pgpath);
1554                 break;
1555         case SCSI_DH_DEV_TEMP_BUSY:
1556                 /*
1557                  * Probably doing something like FW upgrade on the
1558                  * controller so try the other pg.
1559                  */
1560                 bypass_pg(m, pg, true);
1561                 break;
1562         case SCSI_DH_RETRY:
1563                 /* Wait before retrying. */
1564                 delay_retry = true;
1565                 fallthrough;
1566         case SCSI_DH_IMM_RETRY:
1567         case SCSI_DH_RES_TEMP_UNAVAIL:
1568                 if (pg_init_limit_reached(m, pgpath))
1569                         fail_path(pgpath);
1570                 errors = 0;
1571                 break;
1572         case SCSI_DH_DEV_OFFLINED:
1573         default:
1574                 /*
1575                  * We probably do not want to fail the path for a device
1576                  * error, but this is what the old dm did. In future
1577                  * patches we can do more advanced handling.
1578                  */
1579                 fail_path(pgpath);
1580         }
1581
1582         spin_lock_irqsave(&m->lock, flags);
1583         if (errors) {
1584                 if (pgpath == m->current_pgpath) {
1585                         DMERR("Could not failover device. Error %d.", errors);
1586                         m->current_pgpath = NULL;
1587                         m->current_pg = NULL;
1588                 }
1589         } else if (!test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
1590                 pg->bypassed = false;
1591
1592         if (atomic_dec_return(&m->pg_init_in_progress) > 0)
1593                 /* Activations of other paths are still on going */
1594                 goto out;
1595
1596         if (test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags)) {
1597                 if (delay_retry)
1598                         set_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
1599                 else
1600                         clear_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
1601
1602                 if (__pg_init_all_paths(m))
1603                         goto out;
1604         }
1605         clear_bit(MPATHF_QUEUE_IO, &m->flags);
1606
1607         process_queued_io_list(m);
1608
1609         /*
1610          * Wake up any thread waiting to suspend.
1611          */
1612         wake_up(&m->pg_init_wait);
1613
1614 out:
1615         spin_unlock_irqrestore(&m->lock, flags);
1616 }
1617
1618 static void activate_or_offline_path(struct pgpath *pgpath)
1619 {
1620         struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
1621
1622         if (pgpath->is_active && !blk_queue_dying(q))
1623                 scsi_dh_activate(q, pg_init_done, pgpath);
1624         else
1625                 pg_init_done(pgpath, SCSI_DH_DEV_OFFLINED);
1626 }
1627
1628 static void activate_path_work(struct work_struct *work)
1629 {
1630         struct pgpath *pgpath =
1631                 container_of(work, struct pgpath, activate_path.work);
1632
1633         activate_or_offline_path(pgpath);
1634 }
1635
1636 static int multipath_end_io(struct dm_target *ti, struct request *clone,
1637                             blk_status_t error, union map_info *map_context)
1638 {
1639         struct dm_mpath_io *mpio = get_mpio(map_context);
1640         struct pgpath *pgpath = mpio->pgpath;
1641         int r = DM_ENDIO_DONE;
1642
1643         /*
1644          * We don't queue any clone request inside the multipath target
1645          * during end I/O handling, since those clone requests don't have
1646          * bio clones.  If we queue them inside the multipath target,
1647          * we need to make bio clones, that requires memory allocation.
1648          * (See drivers/md/dm-rq.c:end_clone_bio() about why the clone requests
1649          *  don't have bio clones.)
1650          * Instead of queueing the clone request here, we queue the original
1651          * request into dm core, which will remake a clone request and
1652          * clone bios for it and resubmit it later.
1653          */
1654         if (error && blk_path_error(error)) {
1655                 struct multipath *m = ti->private;
1656
1657                 if (error == BLK_STS_RESOURCE)
1658                         r = DM_ENDIO_DELAY_REQUEUE;
1659                 else
1660                         r = DM_ENDIO_REQUEUE;
1661
1662                 if (pgpath)
1663                         fail_path(pgpath);
1664
1665                 if (!atomic_read(&m->nr_valid_paths) &&
1666                     !must_push_back_rq(m)) {
1667                         if (error == BLK_STS_IOERR)
1668                                 dm_report_EIO(m);
1669                         /* complete with the original error */
1670                         r = DM_ENDIO_DONE;
1671                 }
1672         }
1673
1674         if (pgpath) {
1675                 struct path_selector *ps = &pgpath->pg->ps;
1676
1677                 if (ps->type->end_io)
1678                         ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes,
1679                                          clone->io_start_time_ns);
1680         }
1681
1682         return r;
1683 }
1684
1685 static int multipath_end_io_bio(struct dm_target *ti, struct bio *clone,
1686                                 blk_status_t *error)
1687 {
1688         struct multipath *m = ti->private;
1689         struct dm_mpath_io *mpio = get_mpio_from_bio(clone);
1690         struct pgpath *pgpath = mpio->pgpath;
1691         unsigned long flags;
1692         int r = DM_ENDIO_DONE;
1693
1694         if (!*error || !blk_path_error(*error))
1695                 goto done;
1696
1697         if (pgpath)
1698                 fail_path(pgpath);
1699
1700         if (!atomic_read(&m->nr_valid_paths)) {
1701                 spin_lock_irqsave(&m->lock, flags);
1702                 if (!test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
1703                         if (__must_push_back(m)) {
1704                                 r = DM_ENDIO_REQUEUE;
1705                         } else {
1706                                 dm_report_EIO(m);
1707                                 *error = BLK_STS_IOERR;
1708                         }
1709                         spin_unlock_irqrestore(&m->lock, flags);
1710                         goto done;
1711                 }
1712                 spin_unlock_irqrestore(&m->lock, flags);
1713         }
1714
1715         multipath_queue_bio(m, clone);
1716         r = DM_ENDIO_INCOMPLETE;
1717 done:
1718         if (pgpath) {
1719                 struct path_selector *ps = &pgpath->pg->ps;
1720
1721                 if (ps->type->end_io)
1722                         ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes,
1723                                          dm_start_time_ns_from_clone(clone));
1724         }
1725
1726         return r;
1727 }
1728
1729 /*
1730  * Suspend with flush can't complete until all the I/O is processed
1731  * so if the last path fails we must error any remaining I/O.
1732  * - Note that if the freeze_bdev fails while suspending, the
1733  *   queue_if_no_path state is lost - userspace should reset it.
1734  * Otherwise, during noflush suspend, queue_if_no_path will not change.
1735  */
1736 static void multipath_presuspend(struct dm_target *ti)
1737 {
1738         struct multipath *m = ti->private;
1739
1740         /* FIXME: bio-based shouldn't need to always disable queue_if_no_path */
1741         if (m->queue_mode == DM_TYPE_BIO_BASED || !dm_noflush_suspending(m->ti))
1742                 queue_if_no_path(m, false, true, __func__);
1743 }
1744
1745 static void multipath_postsuspend(struct dm_target *ti)
1746 {
1747         struct multipath *m = ti->private;
1748
1749         mutex_lock(&m->work_mutex);
1750         flush_multipath_work(m);
1751         mutex_unlock(&m->work_mutex);
1752 }
1753
1754 /*
1755  * Restore the queue_if_no_path setting.
1756  */
1757 static void multipath_resume(struct dm_target *ti)
1758 {
1759         struct multipath *m = ti->private;
1760         unsigned long flags;
1761
1762         spin_lock_irqsave(&m->lock, flags);
1763         if (test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags)) {
1764                 set_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
1765                 clear_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
1766         }
1767
1768         DMDEBUG("%s: %s finished; QIFNP = %d; SQIFNP = %d",
1769                 dm_device_name(dm_table_get_md(m->ti->table)), __func__,
1770                 test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags),
1771                 test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags));
1772
1773         spin_unlock_irqrestore(&m->lock, flags);
1774 }
1775
1776 /*
1777  * Info output has the following format:
1778  * num_multipath_feature_args [multipath_feature_args]*
1779  * num_handler_status_args [handler_status_args]*
1780  * num_groups init_group_number
1781  *            [A|D|E num_ps_status_args [ps_status_args]*
1782  *             num_paths num_selector_args
1783  *             [path_dev A|F fail_count [selector_args]* ]+ ]+
1784  *
1785  * Table output has the following format (identical to the constructor string):
1786  * num_feature_args [features_args]*
1787  * num_handler_args hw_handler [hw_handler_args]*
1788  * num_groups init_group_number
1789  *     [priority selector-name num_ps_args [ps_args]*
1790  *      num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
1791  */
1792 static void multipath_status(struct dm_target *ti, status_type_t type,
1793                              unsigned status_flags, char *result, unsigned maxlen)
1794 {
1795         int sz = 0;
1796         unsigned long flags;
1797         struct multipath *m = ti->private;
1798         struct priority_group *pg;
1799         struct pgpath *p;
1800         unsigned pg_num;
1801         char state;
1802
1803         spin_lock_irqsave(&m->lock, flags);
1804
1805         /* Features */
1806         if (type == STATUSTYPE_INFO)
1807                 DMEMIT("2 %u %u ", test_bit(MPATHF_QUEUE_IO, &m->flags),
1808                        atomic_read(&m->pg_init_count));
1809         else {
1810                 DMEMIT("%u ", test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) +
1811                               (m->pg_init_retries > 0) * 2 +
1812                               (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT) * 2 +
1813                               test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags) +
1814                               (m->queue_mode != DM_TYPE_REQUEST_BASED) * 2);
1815
1816                 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
1817                         DMEMIT("queue_if_no_path ");
1818                 if (m->pg_init_retries)
1819                         DMEMIT("pg_init_retries %u ", m->pg_init_retries);
1820                 if (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT)
1821                         DMEMIT("pg_init_delay_msecs %u ", m->pg_init_delay_msecs);
1822                 if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags))
1823                         DMEMIT("retain_attached_hw_handler ");
1824                 if (m->queue_mode != DM_TYPE_REQUEST_BASED) {
1825                         switch(m->queue_mode) {
1826                         case DM_TYPE_BIO_BASED:
1827                                 DMEMIT("queue_mode bio ");
1828                                 break;
1829                         default:
1830                                 WARN_ON_ONCE(true);
1831                                 break;
1832                         }
1833                 }
1834         }
1835
1836         if (!m->hw_handler_name || type == STATUSTYPE_INFO)
1837                 DMEMIT("0 ");
1838         else
1839                 DMEMIT("1 %s ", m->hw_handler_name);
1840
1841         DMEMIT("%u ", m->nr_priority_groups);
1842
1843         if (m->next_pg)
1844                 pg_num = m->next_pg->pg_num;
1845         else if (m->current_pg)
1846                 pg_num = m->current_pg->pg_num;
1847         else
1848                 pg_num = (m->nr_priority_groups ? 1 : 0);
1849
1850         DMEMIT("%u ", pg_num);
1851
1852         switch (type) {
1853         case STATUSTYPE_INFO:
1854                 list_for_each_entry(pg, &m->priority_groups, list) {
1855                         if (pg->bypassed)
1856                                 state = 'D';    /* Disabled */
1857                         else if (pg == m->current_pg)
1858                                 state = 'A';    /* Currently Active */
1859                         else
1860                                 state = 'E';    /* Enabled */
1861
1862                         DMEMIT("%c ", state);
1863
1864                         if (pg->ps.type->status)
1865                                 sz += pg->ps.type->status(&pg->ps, NULL, type,
1866                                                           result + sz,
1867                                                           maxlen - sz);
1868                         else
1869                                 DMEMIT("0 ");
1870
1871                         DMEMIT("%u %u ", pg->nr_pgpaths,
1872                                pg->ps.type->info_args);
1873
1874                         list_for_each_entry(p, &pg->pgpaths, list) {
1875                                 DMEMIT("%s %s %u ", p->path.dev->name,
1876                                        p->is_active ? "A" : "F",
1877                                        p->fail_count);
1878                                 if (pg->ps.type->status)
1879                                         sz += pg->ps.type->status(&pg->ps,
1880                                               &p->path, type, result + sz,
1881                                               maxlen - sz);
1882                         }
1883                 }
1884                 break;
1885
1886         case STATUSTYPE_TABLE:
1887                 list_for_each_entry(pg, &m->priority_groups, list) {
1888                         DMEMIT("%s ", pg->ps.type->name);
1889
1890                         if (pg->ps.type->status)
1891                                 sz += pg->ps.type->status(&pg->ps, NULL, type,
1892                                                           result + sz,
1893                                                           maxlen - sz);
1894                         else
1895                                 DMEMIT("0 ");
1896
1897                         DMEMIT("%u %u ", pg->nr_pgpaths,
1898                                pg->ps.type->table_args);
1899
1900                         list_for_each_entry(p, &pg->pgpaths, list) {
1901                                 DMEMIT("%s ", p->path.dev->name);
1902                                 if (pg->ps.type->status)
1903                                         sz += pg->ps.type->status(&pg->ps,
1904                                               &p->path, type, result + sz,
1905                                               maxlen - sz);
1906                         }
1907                 }
1908                 break;
1909         }
1910
1911         spin_unlock_irqrestore(&m->lock, flags);
1912 }
1913
1914 static int multipath_message(struct dm_target *ti, unsigned argc, char **argv,
1915                              char *result, unsigned maxlen)
1916 {
1917         int r = -EINVAL;
1918         struct dm_dev *dev;
1919         struct multipath *m = ti->private;
1920         action_fn action;
1921         unsigned long flags;
1922
1923         mutex_lock(&m->work_mutex);
1924
1925         if (dm_suspended(ti)) {
1926                 r = -EBUSY;
1927                 goto out;
1928         }
1929
1930         if (argc == 1) {
1931                 if (!strcasecmp(argv[0], "queue_if_no_path")) {
1932                         r = queue_if_no_path(m, true, false, __func__);
1933                         spin_lock_irqsave(&m->lock, flags);
1934                         enable_nopath_timeout(m);
1935                         spin_unlock_irqrestore(&m->lock, flags);
1936                         goto out;
1937                 } else if (!strcasecmp(argv[0], "fail_if_no_path")) {
1938                         r = queue_if_no_path(m, false, false, __func__);
1939                         disable_nopath_timeout(m);
1940                         goto out;
1941                 }
1942         }
1943
1944         if (argc != 2) {
1945                 DMWARN("Invalid multipath message arguments. Expected 2 arguments, got %d.", argc);
1946                 goto out;
1947         }
1948
1949         if (!strcasecmp(argv[0], "disable_group")) {
1950                 r = bypass_pg_num(m, argv[1], true);
1951                 goto out;
1952         } else if (!strcasecmp(argv[0], "enable_group")) {
1953                 r = bypass_pg_num(m, argv[1], false);
1954                 goto out;
1955         } else if (!strcasecmp(argv[0], "switch_group")) {
1956                 r = switch_pg_num(m, argv[1]);
1957                 goto out;
1958         } else if (!strcasecmp(argv[0], "reinstate_path"))
1959                 action = reinstate_path;
1960         else if (!strcasecmp(argv[0], "fail_path"))
1961                 action = fail_path;
1962         else {
1963                 DMWARN("Unrecognised multipath message received: %s", argv[0]);
1964                 goto out;
1965         }
1966
1967         r = dm_get_device(ti, argv[1], dm_table_get_mode(ti->table), &dev);
1968         if (r) {
1969                 DMWARN("message: error getting device %s",
1970                        argv[1]);
1971                 goto out;
1972         }
1973
1974         r = action_dev(m, dev, action);
1975
1976         dm_put_device(ti, dev);
1977
1978 out:
1979         mutex_unlock(&m->work_mutex);
1980         return r;
1981 }
1982
1983 static int multipath_prepare_ioctl(struct dm_target *ti,
1984                                    struct block_device **bdev)
1985 {
1986         struct multipath *m = ti->private;
1987         struct pgpath *pgpath;
1988         unsigned long flags;
1989         int r;
1990
1991         pgpath = READ_ONCE(m->current_pgpath);
1992         if (!pgpath || !mpath_double_check_test_bit(MPATHF_QUEUE_IO, m))
1993                 pgpath = choose_pgpath(m, 0);
1994
1995         if (pgpath) {
1996                 if (!mpath_double_check_test_bit(MPATHF_QUEUE_IO, m)) {
1997                         *bdev = pgpath->path.dev->bdev;
1998                         r = 0;
1999                 } else {
2000                         /* pg_init has not started or completed */
2001                         r = -ENOTCONN;
2002                 }
2003         } else {
2004                 /* No path is available */
2005                 r = -EIO;
2006                 spin_lock_irqsave(&m->lock, flags);
2007                 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
2008                         r = -ENOTCONN;
2009                 spin_unlock_irqrestore(&m->lock, flags);
2010         }
2011
2012         if (r == -ENOTCONN) {
2013                 if (!READ_ONCE(m->current_pg)) {
2014                         /* Path status changed, redo selection */
2015                         (void) choose_pgpath(m, 0);
2016                 }
2017                 spin_lock_irqsave(&m->lock, flags);
2018                 if (test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
2019                         (void) __pg_init_all_paths(m);
2020                 spin_unlock_irqrestore(&m->lock, flags);
2021                 dm_table_run_md_queue_async(m->ti->table);
2022                 process_queued_io_list(m);
2023         }
2024
2025         /*
2026          * Only pass ioctls through if the device sizes match exactly.
2027          */
2028         if (!r && ti->len != i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT)
2029                 return 1;
2030         return r;
2031 }
2032
2033 static int multipath_iterate_devices(struct dm_target *ti,
2034                                      iterate_devices_callout_fn fn, void *data)
2035 {
2036         struct multipath *m = ti->private;
2037         struct priority_group *pg;
2038         struct pgpath *p;
2039         int ret = 0;
2040
2041         list_for_each_entry(pg, &m->priority_groups, list) {
2042                 list_for_each_entry(p, &pg->pgpaths, list) {
2043                         ret = fn(ti, p->path.dev, ti->begin, ti->len, data);
2044                         if (ret)
2045                                 goto out;
2046                 }
2047         }
2048
2049 out:
2050         return ret;
2051 }
2052
2053 static int pgpath_busy(struct pgpath *pgpath)
2054 {
2055         struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
2056
2057         return blk_lld_busy(q);
2058 }
2059
2060 /*
2061  * We return "busy", only when we can map I/Os but underlying devices
2062  * are busy (so even if we map I/Os now, the I/Os will wait on
2063  * the underlying queue).
2064  * In other words, if we want to kill I/Os or queue them inside us
2065  * due to map unavailability, we don't return "busy".  Otherwise,
2066  * dm core won't give us the I/Os and we can't do what we want.
2067  */
2068 static int multipath_busy(struct dm_target *ti)
2069 {
2070         bool busy = false, has_active = false;
2071         struct multipath *m = ti->private;
2072         struct priority_group *pg, *next_pg;
2073         struct pgpath *pgpath;
2074
2075         /* pg_init in progress */
2076         if (atomic_read(&m->pg_init_in_progress))
2077                 return true;
2078
2079         /* no paths available, for blk-mq: rely on IO mapping to delay requeue */
2080         if (!atomic_read(&m->nr_valid_paths)) {
2081                 unsigned long flags;
2082                 spin_lock_irqsave(&m->lock, flags);
2083                 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
2084                         spin_unlock_irqrestore(&m->lock, flags);
2085                         return (m->queue_mode != DM_TYPE_REQUEST_BASED);
2086                 }
2087                 spin_unlock_irqrestore(&m->lock, flags);
2088         }
2089
2090         /* Guess which priority_group will be used at next mapping time */
2091         pg = READ_ONCE(m->current_pg);
2092         next_pg = READ_ONCE(m->next_pg);
2093         if (unlikely(!READ_ONCE(m->current_pgpath) && next_pg))
2094                 pg = next_pg;
2095
2096         if (!pg) {
2097                 /*
2098                  * We don't know which pg will be used at next mapping time.
2099                  * We don't call choose_pgpath() here to avoid to trigger
2100                  * pg_init just by busy checking.
2101                  * So we don't know whether underlying devices we will be using
2102                  * at next mapping time are busy or not. Just try mapping.
2103                  */
2104                 return busy;
2105         }
2106
2107         /*
2108          * If there is one non-busy active path at least, the path selector
2109          * will be able to select it. So we consider such a pg as not busy.
2110          */
2111         busy = true;
2112         list_for_each_entry(pgpath, &pg->pgpaths, list) {
2113                 if (pgpath->is_active) {
2114                         has_active = true;
2115                         if (!pgpath_busy(pgpath)) {
2116                                 busy = false;
2117                                 break;
2118                         }
2119                 }
2120         }
2121
2122         if (!has_active) {
2123                 /*
2124                  * No active path in this pg, so this pg won't be used and
2125                  * the current_pg will be changed at next mapping time.
2126                  * We need to try mapping to determine it.
2127                  */
2128                 busy = false;
2129         }
2130
2131         return busy;
2132 }
2133
2134 /*-----------------------------------------------------------------
2135  * Module setup
2136  *---------------------------------------------------------------*/
2137 static struct target_type multipath_target = {
2138         .name = "multipath",
2139         .version = {1, 14, 0},
2140         .features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE |
2141                     DM_TARGET_PASSES_INTEGRITY,
2142         .module = THIS_MODULE,
2143         .ctr = multipath_ctr,
2144         .dtr = multipath_dtr,
2145         .clone_and_map_rq = multipath_clone_and_map,
2146         .release_clone_rq = multipath_release_clone,
2147         .rq_end_io = multipath_end_io,
2148         .map = multipath_map_bio,
2149         .end_io = multipath_end_io_bio,
2150         .presuspend = multipath_presuspend,
2151         .postsuspend = multipath_postsuspend,
2152         .resume = multipath_resume,
2153         .status = multipath_status,
2154         .message = multipath_message,
2155         .prepare_ioctl = multipath_prepare_ioctl,
2156         .iterate_devices = multipath_iterate_devices,
2157         .busy = multipath_busy,
2158 };
2159
2160 static int __init dm_multipath_init(void)
2161 {
2162         int r;
2163
2164         kmultipathd = alloc_workqueue("kmpathd", WQ_MEM_RECLAIM, 0);
2165         if (!kmultipathd) {
2166                 DMERR("failed to create workqueue kmpathd");
2167                 r = -ENOMEM;
2168                 goto bad_alloc_kmultipathd;
2169         }
2170
2171         /*
2172          * A separate workqueue is used to handle the device handlers
2173          * to avoid overloading existing workqueue. Overloading the
2174          * old workqueue would also create a bottleneck in the
2175          * path of the storage hardware device activation.
2176          */
2177         kmpath_handlerd = alloc_ordered_workqueue("kmpath_handlerd",
2178                                                   WQ_MEM_RECLAIM);
2179         if (!kmpath_handlerd) {
2180                 DMERR("failed to create workqueue kmpath_handlerd");
2181                 r = -ENOMEM;
2182                 goto bad_alloc_kmpath_handlerd;
2183         }
2184
2185         r = dm_register_target(&multipath_target);
2186         if (r < 0) {
2187                 DMERR("request-based register failed %d", r);
2188                 r = -EINVAL;
2189                 goto bad_register_target;
2190         }
2191
2192         return 0;
2193
2194 bad_register_target:
2195         destroy_workqueue(kmpath_handlerd);
2196 bad_alloc_kmpath_handlerd:
2197         destroy_workqueue(kmultipathd);
2198 bad_alloc_kmultipathd:
2199         return r;
2200 }
2201
2202 static void __exit dm_multipath_exit(void)
2203 {
2204         destroy_workqueue(kmpath_handlerd);
2205         destroy_workqueue(kmultipathd);
2206
2207         dm_unregister_target(&multipath_target);
2208 }
2209
2210 module_init(dm_multipath_init);
2211 module_exit(dm_multipath_exit);
2212
2213 module_param_named(queue_if_no_path_timeout_secs,
2214                    queue_if_no_path_timeout_secs, ulong, S_IRUGO | S_IWUSR);
2215 MODULE_PARM_DESC(queue_if_no_path_timeout_secs, "No available paths queue IO timeout in seconds");
2216
2217 MODULE_DESCRIPTION(DM_NAME " multipath target");
2218 MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
2219 MODULE_LICENSE("GPL");