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Merge tag 'nfs-for-4.9-2' of git://git.linux-nfs.org/projects/anna/linux-nfs
[mirror_ubuntu-bionic-kernel.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/workqueue.h>
24 #include <linux/delay.h>
25 #include <scsi/scsi_dh.h>
26 #include <linux/atomic.h>
27 #include <linux/blk-mq.h>
28
29 #define DM_MSG_PREFIX "multipath"
30 #define DM_PG_INIT_DELAY_MSECS 2000
31 #define DM_PG_INIT_DELAY_DEFAULT ((unsigned) -1)
32
33 /* Path properties */
34 struct pgpath {
35 struct list_head list;
36
37 struct priority_group *pg; /* Owning PG */
38 unsigned fail_count; /* Cumulative failure count */
39
40 struct dm_path path;
41 struct delayed_work activate_path;
42
43 bool is_active:1; /* Path status */
44 };
45
46 #define path_to_pgpath(__pgp) container_of((__pgp), struct pgpath, path)
47
48 /*
49 * Paths are grouped into Priority Groups and numbered from 1 upwards.
50 * Each has a path selector which controls which path gets used.
51 */
52 struct priority_group {
53 struct list_head list;
54
55 struct multipath *m; /* Owning multipath instance */
56 struct path_selector ps;
57
58 unsigned pg_num; /* Reference number */
59 unsigned nr_pgpaths; /* Number of paths in PG */
60 struct list_head pgpaths;
61
62 bool bypassed:1; /* Temporarily bypass this PG? */
63 };
64
65 /* Multipath context */
66 struct multipath {
67 struct list_head list;
68 struct dm_target *ti;
69
70 const char *hw_handler_name;
71 char *hw_handler_params;
72
73 spinlock_t lock;
74
75 unsigned nr_priority_groups;
76 struct list_head priority_groups;
77
78 wait_queue_head_t pg_init_wait; /* Wait for pg_init completion */
79
80 struct pgpath *current_pgpath;
81 struct priority_group *current_pg;
82 struct priority_group *next_pg; /* Switch to this PG if set */
83
84 unsigned long flags; /* Multipath state flags */
85
86 unsigned pg_init_retries; /* Number of times to retry pg_init */
87 unsigned pg_init_delay_msecs; /* Number of msecs before pg_init retry */
88
89 atomic_t nr_valid_paths; /* Total number of usable paths */
90 atomic_t pg_init_in_progress; /* Only one pg_init allowed at once */
91 atomic_t pg_init_count; /* Number of times pg_init called */
92
93 unsigned queue_mode;
94
95 /*
96 * We must use a mempool of dm_mpath_io structs so that we
97 * can resubmit bios on error.
98 */
99 mempool_t *mpio_pool;
100
101 struct mutex work_mutex;
102 struct work_struct trigger_event;
103
104 struct work_struct process_queued_bios;
105 struct bio_list queued_bios;
106 };
107
108 /*
109 * Context information attached to each io we process.
110 */
111 struct dm_mpath_io {
112 struct pgpath *pgpath;
113 size_t nr_bytes;
114 };
115
116 typedef int (*action_fn) (struct pgpath *pgpath);
117
118 static struct kmem_cache *_mpio_cache;
119
120 static struct workqueue_struct *kmultipathd, *kmpath_handlerd;
121 static void trigger_event(struct work_struct *work);
122 static void activate_path(struct work_struct *work);
123 static void process_queued_bios(struct work_struct *work);
124
125 /*-----------------------------------------------
126 * Multipath state flags.
127 *-----------------------------------------------*/
128
129 #define MPATHF_QUEUE_IO 0 /* Must we queue all I/O? */
130 #define MPATHF_QUEUE_IF_NO_PATH 1 /* Queue I/O if last path fails? */
131 #define MPATHF_SAVED_QUEUE_IF_NO_PATH 2 /* Saved state during suspension */
132 #define MPATHF_RETAIN_ATTACHED_HW_HANDLER 3 /* If there's already a hw_handler present, don't change it. */
133 #define MPATHF_PG_INIT_DISABLED 4 /* pg_init is not currently allowed */
134 #define MPATHF_PG_INIT_REQUIRED 5 /* pg_init needs calling? */
135 #define MPATHF_PG_INIT_DELAY_RETRY 6 /* Delay pg_init retry? */
136
137 /*-----------------------------------------------
138 * Allocation routines
139 *-----------------------------------------------*/
140
141 static struct pgpath *alloc_pgpath(void)
142 {
143 struct pgpath *pgpath = kzalloc(sizeof(*pgpath), GFP_KERNEL);
144
145 if (pgpath) {
146 pgpath->is_active = true;
147 INIT_DELAYED_WORK(&pgpath->activate_path, activate_path);
148 }
149
150 return pgpath;
151 }
152
153 static void free_pgpath(struct pgpath *pgpath)
154 {
155 kfree(pgpath);
156 }
157
158 static struct priority_group *alloc_priority_group(void)
159 {
160 struct priority_group *pg;
161
162 pg = kzalloc(sizeof(*pg), GFP_KERNEL);
163
164 if (pg)
165 INIT_LIST_HEAD(&pg->pgpaths);
166
167 return pg;
168 }
169
170 static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti)
171 {
172 struct pgpath *pgpath, *tmp;
173
174 list_for_each_entry_safe(pgpath, tmp, pgpaths, list) {
175 list_del(&pgpath->list);
176 dm_put_device(ti, pgpath->path.dev);
177 free_pgpath(pgpath);
178 }
179 }
180
181 static void free_priority_group(struct priority_group *pg,
182 struct dm_target *ti)
183 {
184 struct path_selector *ps = &pg->ps;
185
186 if (ps->type) {
187 ps->type->destroy(ps);
188 dm_put_path_selector(ps->type);
189 }
190
191 free_pgpaths(&pg->pgpaths, ti);
192 kfree(pg);
193 }
194
195 static struct multipath *alloc_multipath(struct dm_target *ti)
196 {
197 struct multipath *m;
198
199 m = kzalloc(sizeof(*m), GFP_KERNEL);
200 if (m) {
201 INIT_LIST_HEAD(&m->priority_groups);
202 spin_lock_init(&m->lock);
203 set_bit(MPATHF_QUEUE_IO, &m->flags);
204 atomic_set(&m->nr_valid_paths, 0);
205 atomic_set(&m->pg_init_in_progress, 0);
206 atomic_set(&m->pg_init_count, 0);
207 m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT;
208 INIT_WORK(&m->trigger_event, trigger_event);
209 init_waitqueue_head(&m->pg_init_wait);
210 mutex_init(&m->work_mutex);
211
212 m->mpio_pool = NULL;
213 m->queue_mode = DM_TYPE_NONE;
214
215 m->ti = ti;
216 ti->private = m;
217 }
218
219 return m;
220 }
221
222 static int alloc_multipath_stage2(struct dm_target *ti, struct multipath *m)
223 {
224 if (m->queue_mode == DM_TYPE_NONE) {
225 /*
226 * Default to request-based.
227 */
228 if (dm_use_blk_mq(dm_table_get_md(ti->table)))
229 m->queue_mode = DM_TYPE_MQ_REQUEST_BASED;
230 else
231 m->queue_mode = DM_TYPE_REQUEST_BASED;
232 }
233
234 if (m->queue_mode == DM_TYPE_REQUEST_BASED) {
235 unsigned min_ios = dm_get_reserved_rq_based_ios();
236
237 m->mpio_pool = mempool_create_slab_pool(min_ios, _mpio_cache);
238 if (!m->mpio_pool)
239 return -ENOMEM;
240 }
241 else if (m->queue_mode == DM_TYPE_BIO_BASED) {
242 INIT_WORK(&m->process_queued_bios, process_queued_bios);
243 /*
244 * bio-based doesn't support any direct scsi_dh management;
245 * it just discovers if a scsi_dh is attached.
246 */
247 set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags);
248 }
249
250 dm_table_set_type(ti->table, m->queue_mode);
251
252 return 0;
253 }
254
255 static void free_multipath(struct multipath *m)
256 {
257 struct priority_group *pg, *tmp;
258
259 list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) {
260 list_del(&pg->list);
261 free_priority_group(pg, m->ti);
262 }
263
264 kfree(m->hw_handler_name);
265 kfree(m->hw_handler_params);
266 mempool_destroy(m->mpio_pool);
267 kfree(m);
268 }
269
270 static struct dm_mpath_io *get_mpio(union map_info *info)
271 {
272 return info->ptr;
273 }
274
275 static struct dm_mpath_io *set_mpio(struct multipath *m, union map_info *info)
276 {
277 struct dm_mpath_io *mpio;
278
279 if (!m->mpio_pool) {
280 /* Use blk-mq pdu memory requested via per_io_data_size */
281 mpio = get_mpio(info);
282 memset(mpio, 0, sizeof(*mpio));
283 return mpio;
284 }
285
286 mpio = mempool_alloc(m->mpio_pool, GFP_ATOMIC);
287 if (!mpio)
288 return NULL;
289
290 memset(mpio, 0, sizeof(*mpio));
291 info->ptr = mpio;
292
293 return mpio;
294 }
295
296 static void clear_request_fn_mpio(struct multipath *m, union map_info *info)
297 {
298 /* Only needed for non blk-mq (.request_fn) multipath */
299 if (m->mpio_pool) {
300 struct dm_mpath_io *mpio = info->ptr;
301
302 info->ptr = NULL;
303 mempool_free(mpio, m->mpio_pool);
304 }
305 }
306
307 static size_t multipath_per_bio_data_size(void)
308 {
309 return sizeof(struct dm_mpath_io) + sizeof(struct dm_bio_details);
310 }
311
312 static struct dm_mpath_io *get_mpio_from_bio(struct bio *bio)
313 {
314 return dm_per_bio_data(bio, multipath_per_bio_data_size());
315 }
316
317 static struct dm_bio_details *get_bio_details_from_bio(struct bio *bio)
318 {
319 /* dm_bio_details is immediately after the dm_mpath_io in bio's per-bio-data */
320 struct dm_mpath_io *mpio = get_mpio_from_bio(bio);
321 void *bio_details = mpio + 1;
322
323 return bio_details;
324 }
325
326 static void multipath_init_per_bio_data(struct bio *bio, struct dm_mpath_io **mpio_p,
327 struct dm_bio_details **bio_details_p)
328 {
329 struct dm_mpath_io *mpio = get_mpio_from_bio(bio);
330 struct dm_bio_details *bio_details = get_bio_details_from_bio(bio);
331
332 memset(mpio, 0, sizeof(*mpio));
333 memset(bio_details, 0, sizeof(*bio_details));
334 dm_bio_record(bio_details, bio);
335
336 if (mpio_p)
337 *mpio_p = mpio;
338 if (bio_details_p)
339 *bio_details_p = bio_details;
340 }
341
342 /*-----------------------------------------------
343 * Path selection
344 *-----------------------------------------------*/
345
346 static int __pg_init_all_paths(struct multipath *m)
347 {
348 struct pgpath *pgpath;
349 unsigned long pg_init_delay = 0;
350
351 if (atomic_read(&m->pg_init_in_progress) || test_bit(MPATHF_PG_INIT_DISABLED, &m->flags))
352 return 0;
353
354 atomic_inc(&m->pg_init_count);
355 clear_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
356
357 /* Check here to reset pg_init_required */
358 if (!m->current_pg)
359 return 0;
360
361 if (test_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags))
362 pg_init_delay = msecs_to_jiffies(m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT ?
363 m->pg_init_delay_msecs : DM_PG_INIT_DELAY_MSECS);
364 list_for_each_entry(pgpath, &m->current_pg->pgpaths, list) {
365 /* Skip failed paths */
366 if (!pgpath->is_active)
367 continue;
368 if (queue_delayed_work(kmpath_handlerd, &pgpath->activate_path,
369 pg_init_delay))
370 atomic_inc(&m->pg_init_in_progress);
371 }
372 return atomic_read(&m->pg_init_in_progress);
373 }
374
375 static int pg_init_all_paths(struct multipath *m)
376 {
377 int r;
378 unsigned long flags;
379
380 spin_lock_irqsave(&m->lock, flags);
381 r = __pg_init_all_paths(m);
382 spin_unlock_irqrestore(&m->lock, flags);
383
384 return r;
385 }
386
387 static void __switch_pg(struct multipath *m, struct priority_group *pg)
388 {
389 m->current_pg = pg;
390
391 /* Must we initialise the PG first, and queue I/O till it's ready? */
392 if (m->hw_handler_name) {
393 set_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
394 set_bit(MPATHF_QUEUE_IO, &m->flags);
395 } else {
396 clear_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
397 clear_bit(MPATHF_QUEUE_IO, &m->flags);
398 }
399
400 atomic_set(&m->pg_init_count, 0);
401 }
402
403 static struct pgpath *choose_path_in_pg(struct multipath *m,
404 struct priority_group *pg,
405 size_t nr_bytes)
406 {
407 unsigned long flags;
408 struct dm_path *path;
409 struct pgpath *pgpath;
410
411 path = pg->ps.type->select_path(&pg->ps, nr_bytes);
412 if (!path)
413 return ERR_PTR(-ENXIO);
414
415 pgpath = path_to_pgpath(path);
416
417 if (unlikely(lockless_dereference(m->current_pg) != pg)) {
418 /* Only update current_pgpath if pg changed */
419 spin_lock_irqsave(&m->lock, flags);
420 m->current_pgpath = pgpath;
421 __switch_pg(m, pg);
422 spin_unlock_irqrestore(&m->lock, flags);
423 }
424
425 return pgpath;
426 }
427
428 static struct pgpath *choose_pgpath(struct multipath *m, size_t nr_bytes)
429 {
430 unsigned long flags;
431 struct priority_group *pg;
432 struct pgpath *pgpath;
433 bool bypassed = true;
434
435 if (!atomic_read(&m->nr_valid_paths)) {
436 clear_bit(MPATHF_QUEUE_IO, &m->flags);
437 goto failed;
438 }
439
440 /* Were we instructed to switch PG? */
441 if (lockless_dereference(m->next_pg)) {
442 spin_lock_irqsave(&m->lock, flags);
443 pg = m->next_pg;
444 if (!pg) {
445 spin_unlock_irqrestore(&m->lock, flags);
446 goto check_current_pg;
447 }
448 m->next_pg = NULL;
449 spin_unlock_irqrestore(&m->lock, flags);
450 pgpath = choose_path_in_pg(m, pg, nr_bytes);
451 if (!IS_ERR_OR_NULL(pgpath))
452 return pgpath;
453 }
454
455 /* Don't change PG until it has no remaining paths */
456 check_current_pg:
457 pg = lockless_dereference(m->current_pg);
458 if (pg) {
459 pgpath = choose_path_in_pg(m, pg, nr_bytes);
460 if (!IS_ERR_OR_NULL(pgpath))
461 return pgpath;
462 }
463
464 /*
465 * Loop through priority groups until we find a valid path.
466 * First time we skip PGs marked 'bypassed'.
467 * Second time we only try the ones we skipped, but set
468 * pg_init_delay_retry so we do not hammer controllers.
469 */
470 do {
471 list_for_each_entry(pg, &m->priority_groups, list) {
472 if (pg->bypassed == bypassed)
473 continue;
474 pgpath = choose_path_in_pg(m, pg, nr_bytes);
475 if (!IS_ERR_OR_NULL(pgpath)) {
476 if (!bypassed)
477 set_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
478 return pgpath;
479 }
480 }
481 } while (bypassed--);
482
483 failed:
484 spin_lock_irqsave(&m->lock, flags);
485 m->current_pgpath = NULL;
486 m->current_pg = NULL;
487 spin_unlock_irqrestore(&m->lock, flags);
488
489 return NULL;
490 }
491
492 /*
493 * Check whether bios must be queued in the device-mapper core rather
494 * than here in the target.
495 *
496 * If m->queue_if_no_path and m->saved_queue_if_no_path hold the
497 * same value then we are not between multipath_presuspend()
498 * and multipath_resume() calls and we have no need to check
499 * for the DMF_NOFLUSH_SUSPENDING flag.
500 */
501 static bool __must_push_back(struct multipath *m)
502 {
503 return ((test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) !=
504 test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags)) &&
505 dm_noflush_suspending(m->ti));
506 }
507
508 static bool must_push_back_rq(struct multipath *m)
509 {
510 bool r;
511 unsigned long flags;
512
513 spin_lock_irqsave(&m->lock, flags);
514 r = (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) ||
515 __must_push_back(m));
516 spin_unlock_irqrestore(&m->lock, flags);
517
518 return r;
519 }
520
521 static bool must_push_back_bio(struct multipath *m)
522 {
523 bool r;
524 unsigned long flags;
525
526 spin_lock_irqsave(&m->lock, flags);
527 r = __must_push_back(m);
528 spin_unlock_irqrestore(&m->lock, flags);
529
530 return r;
531 }
532
533 /*
534 * Map cloned requests (request-based multipath)
535 */
536 static int __multipath_map(struct dm_target *ti, struct request *clone,
537 union map_info *map_context,
538 struct request *rq, struct request **__clone)
539 {
540 struct multipath *m = ti->private;
541 int r = DM_MAPIO_REQUEUE;
542 size_t nr_bytes = clone ? blk_rq_bytes(clone) : blk_rq_bytes(rq);
543 struct pgpath *pgpath;
544 struct block_device *bdev;
545 struct dm_mpath_io *mpio;
546
547 /* Do we need to select a new pgpath? */
548 pgpath = lockless_dereference(m->current_pgpath);
549 if (!pgpath || !test_bit(MPATHF_QUEUE_IO, &m->flags))
550 pgpath = choose_pgpath(m, nr_bytes);
551
552 if (!pgpath) {
553 if (must_push_back_rq(m))
554 return DM_MAPIO_DELAY_REQUEUE;
555 return -EIO; /* Failed */
556 } else if (test_bit(MPATHF_QUEUE_IO, &m->flags) ||
557 test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags)) {
558 pg_init_all_paths(m);
559 return r;
560 }
561
562 mpio = set_mpio(m, map_context);
563 if (!mpio)
564 /* ENOMEM, requeue */
565 return r;
566
567 mpio->pgpath = pgpath;
568 mpio->nr_bytes = nr_bytes;
569
570 bdev = pgpath->path.dev->bdev;
571
572 if (clone) {
573 /*
574 * Old request-based interface: allocated clone is passed in.
575 * Used by: .request_fn stacked on .request_fn path(s).
576 */
577 clone->q = bdev_get_queue(bdev);
578 clone->rq_disk = bdev->bd_disk;
579 clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
580 } else {
581 /*
582 * blk-mq request-based interface; used by both:
583 * .request_fn stacked on blk-mq path(s) and
584 * blk-mq stacked on blk-mq path(s).
585 */
586 *__clone = blk_mq_alloc_request(bdev_get_queue(bdev),
587 rq_data_dir(rq), BLK_MQ_REQ_NOWAIT);
588 if (IS_ERR(*__clone)) {
589 /* ENOMEM, requeue */
590 clear_request_fn_mpio(m, map_context);
591 return r;
592 }
593 (*__clone)->bio = (*__clone)->biotail = NULL;
594 (*__clone)->rq_disk = bdev->bd_disk;
595 (*__clone)->cmd_flags |= REQ_FAILFAST_TRANSPORT;
596 }
597
598 if (pgpath->pg->ps.type->start_io)
599 pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
600 &pgpath->path,
601 nr_bytes);
602 return DM_MAPIO_REMAPPED;
603 }
604
605 static int multipath_map(struct dm_target *ti, struct request *clone,
606 union map_info *map_context)
607 {
608 return __multipath_map(ti, clone, map_context, NULL, NULL);
609 }
610
611 static int multipath_clone_and_map(struct dm_target *ti, struct request *rq,
612 union map_info *map_context,
613 struct request **clone)
614 {
615 return __multipath_map(ti, NULL, map_context, rq, clone);
616 }
617
618 static void multipath_release_clone(struct request *clone)
619 {
620 blk_mq_free_request(clone);
621 }
622
623 /*
624 * Map cloned bios (bio-based multipath)
625 */
626 static int __multipath_map_bio(struct multipath *m, struct bio *bio, struct dm_mpath_io *mpio)
627 {
628 size_t nr_bytes = bio->bi_iter.bi_size;
629 struct pgpath *pgpath;
630 unsigned long flags;
631 bool queue_io;
632
633 /* Do we need to select a new pgpath? */
634 pgpath = lockless_dereference(m->current_pgpath);
635 queue_io = test_bit(MPATHF_QUEUE_IO, &m->flags);
636 if (!pgpath || !queue_io)
637 pgpath = choose_pgpath(m, nr_bytes);
638
639 if ((pgpath && queue_io) ||
640 (!pgpath && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))) {
641 /* Queue for the daemon to resubmit */
642 spin_lock_irqsave(&m->lock, flags);
643 bio_list_add(&m->queued_bios, bio);
644 spin_unlock_irqrestore(&m->lock, flags);
645 /* PG_INIT_REQUIRED cannot be set without QUEUE_IO */
646 if (queue_io || test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
647 pg_init_all_paths(m);
648 else if (!queue_io)
649 queue_work(kmultipathd, &m->process_queued_bios);
650 return DM_MAPIO_SUBMITTED;
651 }
652
653 if (!pgpath) {
654 if (!must_push_back_bio(m))
655 return -EIO;
656 return DM_MAPIO_REQUEUE;
657 }
658
659 mpio->pgpath = pgpath;
660 mpio->nr_bytes = nr_bytes;
661
662 bio->bi_error = 0;
663 bio->bi_bdev = pgpath->path.dev->bdev;
664 bio->bi_opf |= REQ_FAILFAST_TRANSPORT;
665
666 if (pgpath->pg->ps.type->start_io)
667 pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
668 &pgpath->path,
669 nr_bytes);
670 return DM_MAPIO_REMAPPED;
671 }
672
673 static int multipath_map_bio(struct dm_target *ti, struct bio *bio)
674 {
675 struct multipath *m = ti->private;
676 struct dm_mpath_io *mpio = NULL;
677
678 multipath_init_per_bio_data(bio, &mpio, NULL);
679
680 return __multipath_map_bio(m, bio, mpio);
681 }
682
683 static void process_queued_io_list(struct multipath *m)
684 {
685 if (m->queue_mode == DM_TYPE_MQ_REQUEST_BASED)
686 dm_mq_kick_requeue_list(dm_table_get_md(m->ti->table));
687 else if (m->queue_mode == DM_TYPE_BIO_BASED)
688 queue_work(kmultipathd, &m->process_queued_bios);
689 }
690
691 static void process_queued_bios(struct work_struct *work)
692 {
693 int r;
694 unsigned long flags;
695 struct bio *bio;
696 struct bio_list bios;
697 struct blk_plug plug;
698 struct multipath *m =
699 container_of(work, struct multipath, process_queued_bios);
700
701 bio_list_init(&bios);
702
703 spin_lock_irqsave(&m->lock, flags);
704
705 if (bio_list_empty(&m->queued_bios)) {
706 spin_unlock_irqrestore(&m->lock, flags);
707 return;
708 }
709
710 bio_list_merge(&bios, &m->queued_bios);
711 bio_list_init(&m->queued_bios);
712
713 spin_unlock_irqrestore(&m->lock, flags);
714
715 blk_start_plug(&plug);
716 while ((bio = bio_list_pop(&bios))) {
717 r = __multipath_map_bio(m, bio, get_mpio_from_bio(bio));
718 if (r < 0 || r == DM_MAPIO_REQUEUE) {
719 bio->bi_error = r;
720 bio_endio(bio);
721 } else if (r == DM_MAPIO_REMAPPED)
722 generic_make_request(bio);
723 }
724 blk_finish_plug(&plug);
725 }
726
727 /*
728 * If we run out of usable paths, should we queue I/O or error it?
729 */
730 static int queue_if_no_path(struct multipath *m, bool queue_if_no_path,
731 bool save_old_value)
732 {
733 unsigned long flags;
734
735 spin_lock_irqsave(&m->lock, flags);
736
737 if (save_old_value) {
738 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
739 set_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
740 else
741 clear_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
742 } else {
743 if (queue_if_no_path)
744 set_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
745 else
746 clear_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
747 }
748 if (queue_if_no_path)
749 set_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
750 else
751 clear_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
752
753 spin_unlock_irqrestore(&m->lock, flags);
754
755 if (!queue_if_no_path) {
756 dm_table_run_md_queue_async(m->ti->table);
757 process_queued_io_list(m);
758 }
759
760 return 0;
761 }
762
763 /*
764 * An event is triggered whenever a path is taken out of use.
765 * Includes path failure and PG bypass.
766 */
767 static void trigger_event(struct work_struct *work)
768 {
769 struct multipath *m =
770 container_of(work, struct multipath, trigger_event);
771
772 dm_table_event(m->ti->table);
773 }
774
775 /*-----------------------------------------------------------------
776 * Constructor/argument parsing:
777 * <#multipath feature args> [<arg>]*
778 * <#hw_handler args> [hw_handler [<arg>]*]
779 * <#priority groups>
780 * <initial priority group>
781 * [<selector> <#selector args> [<arg>]*
782 * <#paths> <#per-path selector args>
783 * [<path> [<arg>]* ]+ ]+
784 *---------------------------------------------------------------*/
785 static int parse_path_selector(struct dm_arg_set *as, struct priority_group *pg,
786 struct dm_target *ti)
787 {
788 int r;
789 struct path_selector_type *pst;
790 unsigned ps_argc;
791
792 static struct dm_arg _args[] = {
793 {0, 1024, "invalid number of path selector args"},
794 };
795
796 pst = dm_get_path_selector(dm_shift_arg(as));
797 if (!pst) {
798 ti->error = "unknown path selector type";
799 return -EINVAL;
800 }
801
802 r = dm_read_arg_group(_args, as, &ps_argc, &ti->error);
803 if (r) {
804 dm_put_path_selector(pst);
805 return -EINVAL;
806 }
807
808 r = pst->create(&pg->ps, ps_argc, as->argv);
809 if (r) {
810 dm_put_path_selector(pst);
811 ti->error = "path selector constructor failed";
812 return r;
813 }
814
815 pg->ps.type = pst;
816 dm_consume_args(as, ps_argc);
817
818 return 0;
819 }
820
821 static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps,
822 struct dm_target *ti)
823 {
824 int r;
825 struct pgpath *p;
826 struct multipath *m = ti->private;
827 struct request_queue *q = NULL;
828 const char *attached_handler_name;
829
830 /* we need at least a path arg */
831 if (as->argc < 1) {
832 ti->error = "no device given";
833 return ERR_PTR(-EINVAL);
834 }
835
836 p = alloc_pgpath();
837 if (!p)
838 return ERR_PTR(-ENOMEM);
839
840 r = dm_get_device(ti, dm_shift_arg(as), dm_table_get_mode(ti->table),
841 &p->path.dev);
842 if (r) {
843 ti->error = "error getting device";
844 goto bad;
845 }
846
847 if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags) || m->hw_handler_name)
848 q = bdev_get_queue(p->path.dev->bdev);
849
850 if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags)) {
851 retain:
852 attached_handler_name = scsi_dh_attached_handler_name(q, GFP_KERNEL);
853 if (attached_handler_name) {
854 /*
855 * Reset hw_handler_name to match the attached handler
856 * and clear any hw_handler_params associated with the
857 * ignored handler.
858 *
859 * NB. This modifies the table line to show the actual
860 * handler instead of the original table passed in.
861 */
862 kfree(m->hw_handler_name);
863 m->hw_handler_name = attached_handler_name;
864
865 kfree(m->hw_handler_params);
866 m->hw_handler_params = NULL;
867 }
868 }
869
870 if (m->hw_handler_name) {
871 r = scsi_dh_attach(q, m->hw_handler_name);
872 if (r == -EBUSY) {
873 char b[BDEVNAME_SIZE];
874
875 printk(KERN_INFO "dm-mpath: retaining handler on device %s\n",
876 bdevname(p->path.dev->bdev, b));
877 goto retain;
878 }
879 if (r < 0) {
880 ti->error = "error attaching hardware handler";
881 dm_put_device(ti, p->path.dev);
882 goto bad;
883 }
884
885 if (m->hw_handler_params) {
886 r = scsi_dh_set_params(q, m->hw_handler_params);
887 if (r < 0) {
888 ti->error = "unable to set hardware "
889 "handler parameters";
890 dm_put_device(ti, p->path.dev);
891 goto bad;
892 }
893 }
894 }
895
896 r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
897 if (r) {
898 dm_put_device(ti, p->path.dev);
899 goto bad;
900 }
901
902 return p;
903
904 bad:
905 free_pgpath(p);
906 return ERR_PTR(r);
907 }
908
909 static struct priority_group *parse_priority_group(struct dm_arg_set *as,
910 struct multipath *m)
911 {
912 static struct dm_arg _args[] = {
913 {1, 1024, "invalid number of paths"},
914 {0, 1024, "invalid number of selector args"}
915 };
916
917 int r;
918 unsigned i, nr_selector_args, nr_args;
919 struct priority_group *pg;
920 struct dm_target *ti = m->ti;
921
922 if (as->argc < 2) {
923 as->argc = 0;
924 ti->error = "not enough priority group arguments";
925 return ERR_PTR(-EINVAL);
926 }
927
928 pg = alloc_priority_group();
929 if (!pg) {
930 ti->error = "couldn't allocate priority group";
931 return ERR_PTR(-ENOMEM);
932 }
933 pg->m = m;
934
935 r = parse_path_selector(as, pg, ti);
936 if (r)
937 goto bad;
938
939 /*
940 * read the paths
941 */
942 r = dm_read_arg(_args, as, &pg->nr_pgpaths, &ti->error);
943 if (r)
944 goto bad;
945
946 r = dm_read_arg(_args + 1, as, &nr_selector_args, &ti->error);
947 if (r)
948 goto bad;
949
950 nr_args = 1 + nr_selector_args;
951 for (i = 0; i < pg->nr_pgpaths; i++) {
952 struct pgpath *pgpath;
953 struct dm_arg_set path_args;
954
955 if (as->argc < nr_args) {
956 ti->error = "not enough path parameters";
957 r = -EINVAL;
958 goto bad;
959 }
960
961 path_args.argc = nr_args;
962 path_args.argv = as->argv;
963
964 pgpath = parse_path(&path_args, &pg->ps, ti);
965 if (IS_ERR(pgpath)) {
966 r = PTR_ERR(pgpath);
967 goto bad;
968 }
969
970 pgpath->pg = pg;
971 list_add_tail(&pgpath->list, &pg->pgpaths);
972 dm_consume_args(as, nr_args);
973 }
974
975 return pg;
976
977 bad:
978 free_priority_group(pg, ti);
979 return ERR_PTR(r);
980 }
981
982 static int parse_hw_handler(struct dm_arg_set *as, struct multipath *m)
983 {
984 unsigned hw_argc;
985 int ret;
986 struct dm_target *ti = m->ti;
987
988 static struct dm_arg _args[] = {
989 {0, 1024, "invalid number of hardware handler args"},
990 };
991
992 if (dm_read_arg_group(_args, as, &hw_argc, &ti->error))
993 return -EINVAL;
994
995 if (!hw_argc)
996 return 0;
997
998 if (m->queue_mode == DM_TYPE_BIO_BASED) {
999 dm_consume_args(as, hw_argc);
1000 DMERR("bio-based multipath doesn't allow hardware handler args");
1001 return 0;
1002 }
1003
1004 m->hw_handler_name = kstrdup(dm_shift_arg(as), GFP_KERNEL);
1005
1006 if (hw_argc > 1) {
1007 char *p;
1008 int i, j, len = 4;
1009
1010 for (i = 0; i <= hw_argc - 2; i++)
1011 len += strlen(as->argv[i]) + 1;
1012 p = m->hw_handler_params = kzalloc(len, GFP_KERNEL);
1013 if (!p) {
1014 ti->error = "memory allocation failed";
1015 ret = -ENOMEM;
1016 goto fail;
1017 }
1018 j = sprintf(p, "%d", hw_argc - 1);
1019 for (i = 0, p+=j+1; i <= hw_argc - 2; i++, p+=j+1)
1020 j = sprintf(p, "%s", as->argv[i]);
1021 }
1022 dm_consume_args(as, hw_argc - 1);
1023
1024 return 0;
1025 fail:
1026 kfree(m->hw_handler_name);
1027 m->hw_handler_name = NULL;
1028 return ret;
1029 }
1030
1031 static int parse_features(struct dm_arg_set *as, struct multipath *m)
1032 {
1033 int r;
1034 unsigned argc;
1035 struct dm_target *ti = m->ti;
1036 const char *arg_name;
1037
1038 static struct dm_arg _args[] = {
1039 {0, 8, "invalid number of feature args"},
1040 {1, 50, "pg_init_retries must be between 1 and 50"},
1041 {0, 60000, "pg_init_delay_msecs must be between 0 and 60000"},
1042 };
1043
1044 r = dm_read_arg_group(_args, as, &argc, &ti->error);
1045 if (r)
1046 return -EINVAL;
1047
1048 if (!argc)
1049 return 0;
1050
1051 do {
1052 arg_name = dm_shift_arg(as);
1053 argc--;
1054
1055 if (!strcasecmp(arg_name, "queue_if_no_path")) {
1056 r = queue_if_no_path(m, true, false);
1057 continue;
1058 }
1059
1060 if (!strcasecmp(arg_name, "retain_attached_hw_handler")) {
1061 set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags);
1062 continue;
1063 }
1064
1065 if (!strcasecmp(arg_name, "pg_init_retries") &&
1066 (argc >= 1)) {
1067 r = dm_read_arg(_args + 1, as, &m->pg_init_retries, &ti->error);
1068 argc--;
1069 continue;
1070 }
1071
1072 if (!strcasecmp(arg_name, "pg_init_delay_msecs") &&
1073 (argc >= 1)) {
1074 r = dm_read_arg(_args + 2, as, &m->pg_init_delay_msecs, &ti->error);
1075 argc--;
1076 continue;
1077 }
1078
1079 if (!strcasecmp(arg_name, "queue_mode") &&
1080 (argc >= 1)) {
1081 const char *queue_mode_name = dm_shift_arg(as);
1082
1083 if (!strcasecmp(queue_mode_name, "bio"))
1084 m->queue_mode = DM_TYPE_BIO_BASED;
1085 else if (!strcasecmp(queue_mode_name, "rq"))
1086 m->queue_mode = DM_TYPE_REQUEST_BASED;
1087 else if (!strcasecmp(queue_mode_name, "mq"))
1088 m->queue_mode = DM_TYPE_MQ_REQUEST_BASED;
1089 else {
1090 ti->error = "Unknown 'queue_mode' requested";
1091 r = -EINVAL;
1092 }
1093 argc--;
1094 continue;
1095 }
1096
1097 ti->error = "Unrecognised multipath feature request";
1098 r = -EINVAL;
1099 } while (argc && !r);
1100
1101 return r;
1102 }
1103
1104 static int multipath_ctr(struct dm_target *ti, unsigned argc, char **argv)
1105 {
1106 /* target arguments */
1107 static struct dm_arg _args[] = {
1108 {0, 1024, "invalid number of priority groups"},
1109 {0, 1024, "invalid initial priority group number"},
1110 };
1111
1112 int r;
1113 struct multipath *m;
1114 struct dm_arg_set as;
1115 unsigned pg_count = 0;
1116 unsigned next_pg_num;
1117
1118 as.argc = argc;
1119 as.argv = argv;
1120
1121 m = alloc_multipath(ti);
1122 if (!m) {
1123 ti->error = "can't allocate multipath";
1124 return -EINVAL;
1125 }
1126
1127 r = parse_features(&as, m);
1128 if (r)
1129 goto bad;
1130
1131 r = alloc_multipath_stage2(ti, m);
1132 if (r)
1133 goto bad;
1134
1135 r = parse_hw_handler(&as, m);
1136 if (r)
1137 goto bad;
1138
1139 r = dm_read_arg(_args, &as, &m->nr_priority_groups, &ti->error);
1140 if (r)
1141 goto bad;
1142
1143 r = dm_read_arg(_args + 1, &as, &next_pg_num, &ti->error);
1144 if (r)
1145 goto bad;
1146
1147 if ((!m->nr_priority_groups && next_pg_num) ||
1148 (m->nr_priority_groups && !next_pg_num)) {
1149 ti->error = "invalid initial priority group";
1150 r = -EINVAL;
1151 goto bad;
1152 }
1153
1154 /* parse the priority groups */
1155 while (as.argc) {
1156 struct priority_group *pg;
1157 unsigned nr_valid_paths = atomic_read(&m->nr_valid_paths);
1158
1159 pg = parse_priority_group(&as, m);
1160 if (IS_ERR(pg)) {
1161 r = PTR_ERR(pg);
1162 goto bad;
1163 }
1164
1165 nr_valid_paths += pg->nr_pgpaths;
1166 atomic_set(&m->nr_valid_paths, nr_valid_paths);
1167
1168 list_add_tail(&pg->list, &m->priority_groups);
1169 pg_count++;
1170 pg->pg_num = pg_count;
1171 if (!--next_pg_num)
1172 m->next_pg = pg;
1173 }
1174
1175 if (pg_count != m->nr_priority_groups) {
1176 ti->error = "priority group count mismatch";
1177 r = -EINVAL;
1178 goto bad;
1179 }
1180
1181 ti->num_flush_bios = 1;
1182 ti->num_discard_bios = 1;
1183 ti->num_write_same_bios = 1;
1184 if (m->queue_mode == DM_TYPE_BIO_BASED)
1185 ti->per_io_data_size = multipath_per_bio_data_size();
1186 else if (m->queue_mode == DM_TYPE_MQ_REQUEST_BASED)
1187 ti->per_io_data_size = sizeof(struct dm_mpath_io);
1188
1189 return 0;
1190
1191 bad:
1192 free_multipath(m);
1193 return r;
1194 }
1195
1196 static void multipath_wait_for_pg_init_completion(struct multipath *m)
1197 {
1198 DEFINE_WAIT(wait);
1199
1200 while (1) {
1201 prepare_to_wait(&m->pg_init_wait, &wait, TASK_UNINTERRUPTIBLE);
1202
1203 if (!atomic_read(&m->pg_init_in_progress))
1204 break;
1205
1206 io_schedule();
1207 }
1208 finish_wait(&m->pg_init_wait, &wait);
1209 }
1210
1211 static void flush_multipath_work(struct multipath *m)
1212 {
1213 set_bit(MPATHF_PG_INIT_DISABLED, &m->flags);
1214 smp_mb__after_atomic();
1215
1216 flush_workqueue(kmpath_handlerd);
1217 multipath_wait_for_pg_init_completion(m);
1218 flush_workqueue(kmultipathd);
1219 flush_work(&m->trigger_event);
1220
1221 clear_bit(MPATHF_PG_INIT_DISABLED, &m->flags);
1222 smp_mb__after_atomic();
1223 }
1224
1225 static void multipath_dtr(struct dm_target *ti)
1226 {
1227 struct multipath *m = ti->private;
1228
1229 flush_multipath_work(m);
1230 free_multipath(m);
1231 }
1232
1233 /*
1234 * Take a path out of use.
1235 */
1236 static int fail_path(struct pgpath *pgpath)
1237 {
1238 unsigned long flags;
1239 struct multipath *m = pgpath->pg->m;
1240
1241 spin_lock_irqsave(&m->lock, flags);
1242
1243 if (!pgpath->is_active)
1244 goto out;
1245
1246 DMWARN("Failing path %s.", pgpath->path.dev->name);
1247
1248 pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
1249 pgpath->is_active = false;
1250 pgpath->fail_count++;
1251
1252 atomic_dec(&m->nr_valid_paths);
1253
1254 if (pgpath == m->current_pgpath)
1255 m->current_pgpath = NULL;
1256
1257 dm_path_uevent(DM_UEVENT_PATH_FAILED, m->ti,
1258 pgpath->path.dev->name, atomic_read(&m->nr_valid_paths));
1259
1260 schedule_work(&m->trigger_event);
1261
1262 out:
1263 spin_unlock_irqrestore(&m->lock, flags);
1264
1265 return 0;
1266 }
1267
1268 /*
1269 * Reinstate a previously-failed path
1270 */
1271 static int reinstate_path(struct pgpath *pgpath)
1272 {
1273 int r = 0, run_queue = 0;
1274 unsigned long flags;
1275 struct multipath *m = pgpath->pg->m;
1276 unsigned nr_valid_paths;
1277
1278 spin_lock_irqsave(&m->lock, flags);
1279
1280 if (pgpath->is_active)
1281 goto out;
1282
1283 DMWARN("Reinstating path %s.", pgpath->path.dev->name);
1284
1285 r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
1286 if (r)
1287 goto out;
1288
1289 pgpath->is_active = true;
1290
1291 nr_valid_paths = atomic_inc_return(&m->nr_valid_paths);
1292 if (nr_valid_paths == 1) {
1293 m->current_pgpath = NULL;
1294 run_queue = 1;
1295 } else if (m->hw_handler_name && (m->current_pg == pgpath->pg)) {
1296 if (queue_work(kmpath_handlerd, &pgpath->activate_path.work))
1297 atomic_inc(&m->pg_init_in_progress);
1298 }
1299
1300 dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti,
1301 pgpath->path.dev->name, nr_valid_paths);
1302
1303 schedule_work(&m->trigger_event);
1304
1305 out:
1306 spin_unlock_irqrestore(&m->lock, flags);
1307 if (run_queue) {
1308 dm_table_run_md_queue_async(m->ti->table);
1309 process_queued_io_list(m);
1310 }
1311
1312 return r;
1313 }
1314
1315 /*
1316 * Fail or reinstate all paths that match the provided struct dm_dev.
1317 */
1318 static int action_dev(struct multipath *m, struct dm_dev *dev,
1319 action_fn action)
1320 {
1321 int r = -EINVAL;
1322 struct pgpath *pgpath;
1323 struct priority_group *pg;
1324
1325 list_for_each_entry(pg, &m->priority_groups, list) {
1326 list_for_each_entry(pgpath, &pg->pgpaths, list) {
1327 if (pgpath->path.dev == dev)
1328 r = action(pgpath);
1329 }
1330 }
1331
1332 return r;
1333 }
1334
1335 /*
1336 * Temporarily try to avoid having to use the specified PG
1337 */
1338 static void bypass_pg(struct multipath *m, struct priority_group *pg,
1339 bool bypassed)
1340 {
1341 unsigned long flags;
1342
1343 spin_lock_irqsave(&m->lock, flags);
1344
1345 pg->bypassed = bypassed;
1346 m->current_pgpath = NULL;
1347 m->current_pg = NULL;
1348
1349 spin_unlock_irqrestore(&m->lock, flags);
1350
1351 schedule_work(&m->trigger_event);
1352 }
1353
1354 /*
1355 * Switch to using the specified PG from the next I/O that gets mapped
1356 */
1357 static int switch_pg_num(struct multipath *m, const char *pgstr)
1358 {
1359 struct priority_group *pg;
1360 unsigned pgnum;
1361 unsigned long flags;
1362 char dummy;
1363
1364 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1365 (pgnum > m->nr_priority_groups)) {
1366 DMWARN("invalid PG number supplied to switch_pg_num");
1367 return -EINVAL;
1368 }
1369
1370 spin_lock_irqsave(&m->lock, flags);
1371 list_for_each_entry(pg, &m->priority_groups, list) {
1372 pg->bypassed = false;
1373 if (--pgnum)
1374 continue;
1375
1376 m->current_pgpath = NULL;
1377 m->current_pg = NULL;
1378 m->next_pg = pg;
1379 }
1380 spin_unlock_irqrestore(&m->lock, flags);
1381
1382 schedule_work(&m->trigger_event);
1383 return 0;
1384 }
1385
1386 /*
1387 * Set/clear bypassed status of a PG.
1388 * PGs are numbered upwards from 1 in the order they were declared.
1389 */
1390 static int bypass_pg_num(struct multipath *m, const char *pgstr, bool bypassed)
1391 {
1392 struct priority_group *pg;
1393 unsigned pgnum;
1394 char dummy;
1395
1396 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1397 (pgnum > m->nr_priority_groups)) {
1398 DMWARN("invalid PG number supplied to bypass_pg");
1399 return -EINVAL;
1400 }
1401
1402 list_for_each_entry(pg, &m->priority_groups, list) {
1403 if (!--pgnum)
1404 break;
1405 }
1406
1407 bypass_pg(m, pg, bypassed);
1408 return 0;
1409 }
1410
1411 /*
1412 * Should we retry pg_init immediately?
1413 */
1414 static bool pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath)
1415 {
1416 unsigned long flags;
1417 bool limit_reached = false;
1418
1419 spin_lock_irqsave(&m->lock, flags);
1420
1421 if (atomic_read(&m->pg_init_count) <= m->pg_init_retries &&
1422 !test_bit(MPATHF_PG_INIT_DISABLED, &m->flags))
1423 set_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
1424 else
1425 limit_reached = true;
1426
1427 spin_unlock_irqrestore(&m->lock, flags);
1428
1429 return limit_reached;
1430 }
1431
1432 static void pg_init_done(void *data, int errors)
1433 {
1434 struct pgpath *pgpath = data;
1435 struct priority_group *pg = pgpath->pg;
1436 struct multipath *m = pg->m;
1437 unsigned long flags;
1438 bool delay_retry = false;
1439
1440 /* device or driver problems */
1441 switch (errors) {
1442 case SCSI_DH_OK:
1443 break;
1444 case SCSI_DH_NOSYS:
1445 if (!m->hw_handler_name) {
1446 errors = 0;
1447 break;
1448 }
1449 DMERR("Could not failover the device: Handler scsi_dh_%s "
1450 "Error %d.", m->hw_handler_name, errors);
1451 /*
1452 * Fail path for now, so we do not ping pong
1453 */
1454 fail_path(pgpath);
1455 break;
1456 case SCSI_DH_DEV_TEMP_BUSY:
1457 /*
1458 * Probably doing something like FW upgrade on the
1459 * controller so try the other pg.
1460 */
1461 bypass_pg(m, pg, true);
1462 break;
1463 case SCSI_DH_RETRY:
1464 /* Wait before retrying. */
1465 delay_retry = 1;
1466 case SCSI_DH_IMM_RETRY:
1467 case SCSI_DH_RES_TEMP_UNAVAIL:
1468 if (pg_init_limit_reached(m, pgpath))
1469 fail_path(pgpath);
1470 errors = 0;
1471 break;
1472 case SCSI_DH_DEV_OFFLINED:
1473 default:
1474 /*
1475 * We probably do not want to fail the path for a device
1476 * error, but this is what the old dm did. In future
1477 * patches we can do more advanced handling.
1478 */
1479 fail_path(pgpath);
1480 }
1481
1482 spin_lock_irqsave(&m->lock, flags);
1483 if (errors) {
1484 if (pgpath == m->current_pgpath) {
1485 DMERR("Could not failover device. Error %d.", errors);
1486 m->current_pgpath = NULL;
1487 m->current_pg = NULL;
1488 }
1489 } else if (!test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
1490 pg->bypassed = false;
1491
1492 if (atomic_dec_return(&m->pg_init_in_progress) > 0)
1493 /* Activations of other paths are still on going */
1494 goto out;
1495
1496 if (test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags)) {
1497 if (delay_retry)
1498 set_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
1499 else
1500 clear_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
1501
1502 if (__pg_init_all_paths(m))
1503 goto out;
1504 }
1505 clear_bit(MPATHF_QUEUE_IO, &m->flags);
1506
1507 process_queued_io_list(m);
1508
1509 /*
1510 * Wake up any thread waiting to suspend.
1511 */
1512 wake_up(&m->pg_init_wait);
1513
1514 out:
1515 spin_unlock_irqrestore(&m->lock, flags);
1516 }
1517
1518 static void activate_path(struct work_struct *work)
1519 {
1520 struct pgpath *pgpath =
1521 container_of(work, struct pgpath, activate_path.work);
1522 struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
1523
1524 if (pgpath->is_active && !blk_queue_dying(q))
1525 scsi_dh_activate(q, pg_init_done, pgpath);
1526 else
1527 pg_init_done(pgpath, SCSI_DH_DEV_OFFLINED);
1528 }
1529
1530 static int noretry_error(int error)
1531 {
1532 switch (error) {
1533 case -EBADE:
1534 /*
1535 * EBADE signals an reservation conflict.
1536 * We shouldn't fail the path here as we can communicate with
1537 * the target. We should failover to the next path, but in
1538 * doing so we might be causing a ping-pong between paths.
1539 * So just return the reservation conflict error.
1540 */
1541 case -EOPNOTSUPP:
1542 case -EREMOTEIO:
1543 case -EILSEQ:
1544 case -ENODATA:
1545 case -ENOSPC:
1546 return 1;
1547 }
1548
1549 /* Anything else could be a path failure, so should be retried */
1550 return 0;
1551 }
1552
1553 /*
1554 * end_io handling
1555 */
1556 static int do_end_io(struct multipath *m, struct request *clone,
1557 int error, struct dm_mpath_io *mpio)
1558 {
1559 /*
1560 * We don't queue any clone request inside the multipath target
1561 * during end I/O handling, since those clone requests don't have
1562 * bio clones. If we queue them inside the multipath target,
1563 * we need to make bio clones, that requires memory allocation.
1564 * (See drivers/md/dm-rq.c:end_clone_bio() about why the clone requests
1565 * don't have bio clones.)
1566 * Instead of queueing the clone request here, we queue the original
1567 * request into dm core, which will remake a clone request and
1568 * clone bios for it and resubmit it later.
1569 */
1570 int r = DM_ENDIO_REQUEUE;
1571
1572 if (!error && !clone->errors)
1573 return 0; /* I/O complete */
1574
1575 if (noretry_error(error))
1576 return error;
1577
1578 if (mpio->pgpath)
1579 fail_path(mpio->pgpath);
1580
1581 if (!atomic_read(&m->nr_valid_paths)) {
1582 if (!test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
1583 if (!must_push_back_rq(m))
1584 r = -EIO;
1585 }
1586 }
1587
1588 return r;
1589 }
1590
1591 static int multipath_end_io(struct dm_target *ti, struct request *clone,
1592 int error, union map_info *map_context)
1593 {
1594 struct multipath *m = ti->private;
1595 struct dm_mpath_io *mpio = get_mpio(map_context);
1596 struct pgpath *pgpath;
1597 struct path_selector *ps;
1598 int r;
1599
1600 BUG_ON(!mpio);
1601
1602 r = do_end_io(m, clone, error, mpio);
1603 pgpath = mpio->pgpath;
1604 if (pgpath) {
1605 ps = &pgpath->pg->ps;
1606 if (ps->type->end_io)
1607 ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
1608 }
1609 clear_request_fn_mpio(m, map_context);
1610
1611 return r;
1612 }
1613
1614 static int do_end_io_bio(struct multipath *m, struct bio *clone,
1615 int error, struct dm_mpath_io *mpio)
1616 {
1617 unsigned long flags;
1618
1619 if (!error)
1620 return 0; /* I/O complete */
1621
1622 if (noretry_error(error))
1623 return error;
1624
1625 if (mpio->pgpath)
1626 fail_path(mpio->pgpath);
1627
1628 if (!atomic_read(&m->nr_valid_paths)) {
1629 if (!test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
1630 if (!must_push_back_bio(m))
1631 return -EIO;
1632 return DM_ENDIO_REQUEUE;
1633 }
1634 }
1635
1636 /* Queue for the daemon to resubmit */
1637 dm_bio_restore(get_bio_details_from_bio(clone), clone);
1638
1639 spin_lock_irqsave(&m->lock, flags);
1640 bio_list_add(&m->queued_bios, clone);
1641 spin_unlock_irqrestore(&m->lock, flags);
1642 if (!test_bit(MPATHF_QUEUE_IO, &m->flags))
1643 queue_work(kmultipathd, &m->process_queued_bios);
1644
1645 return DM_ENDIO_INCOMPLETE;
1646 }
1647
1648 static int multipath_end_io_bio(struct dm_target *ti, struct bio *clone, int error)
1649 {
1650 struct multipath *m = ti->private;
1651 struct dm_mpath_io *mpio = get_mpio_from_bio(clone);
1652 struct pgpath *pgpath;
1653 struct path_selector *ps;
1654 int r;
1655
1656 BUG_ON(!mpio);
1657
1658 r = do_end_io_bio(m, clone, error, mpio);
1659 pgpath = mpio->pgpath;
1660 if (pgpath) {
1661 ps = &pgpath->pg->ps;
1662 if (ps->type->end_io)
1663 ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
1664 }
1665
1666 return r;
1667 }
1668
1669 /*
1670 * Suspend can't complete until all the I/O is processed so if
1671 * the last path fails we must error any remaining I/O.
1672 * Note that if the freeze_bdev fails while suspending, the
1673 * queue_if_no_path state is lost - userspace should reset it.
1674 */
1675 static void multipath_presuspend(struct dm_target *ti)
1676 {
1677 struct multipath *m = ti->private;
1678
1679 queue_if_no_path(m, false, true);
1680 }
1681
1682 static void multipath_postsuspend(struct dm_target *ti)
1683 {
1684 struct multipath *m = ti->private;
1685
1686 mutex_lock(&m->work_mutex);
1687 flush_multipath_work(m);
1688 mutex_unlock(&m->work_mutex);
1689 }
1690
1691 /*
1692 * Restore the queue_if_no_path setting.
1693 */
1694 static void multipath_resume(struct dm_target *ti)
1695 {
1696 struct multipath *m = ti->private;
1697 unsigned long flags;
1698
1699 spin_lock_irqsave(&m->lock, flags);
1700 if (test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags))
1701 set_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
1702 else
1703 clear_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
1704 spin_unlock_irqrestore(&m->lock, flags);
1705 }
1706
1707 /*
1708 * Info output has the following format:
1709 * num_multipath_feature_args [multipath_feature_args]*
1710 * num_handler_status_args [handler_status_args]*
1711 * num_groups init_group_number
1712 * [A|D|E num_ps_status_args [ps_status_args]*
1713 * num_paths num_selector_args
1714 * [path_dev A|F fail_count [selector_args]* ]+ ]+
1715 *
1716 * Table output has the following format (identical to the constructor string):
1717 * num_feature_args [features_args]*
1718 * num_handler_args hw_handler [hw_handler_args]*
1719 * num_groups init_group_number
1720 * [priority selector-name num_ps_args [ps_args]*
1721 * num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
1722 */
1723 static void multipath_status(struct dm_target *ti, status_type_t type,
1724 unsigned status_flags, char *result, unsigned maxlen)
1725 {
1726 int sz = 0;
1727 unsigned long flags;
1728 struct multipath *m = ti->private;
1729 struct priority_group *pg;
1730 struct pgpath *p;
1731 unsigned pg_num;
1732 char state;
1733
1734 spin_lock_irqsave(&m->lock, flags);
1735
1736 /* Features */
1737 if (type == STATUSTYPE_INFO)
1738 DMEMIT("2 %u %u ", test_bit(MPATHF_QUEUE_IO, &m->flags),
1739 atomic_read(&m->pg_init_count));
1740 else {
1741 DMEMIT("%u ", test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) +
1742 (m->pg_init_retries > 0) * 2 +
1743 (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT) * 2 +
1744 test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags) +
1745 (m->queue_mode != DM_TYPE_REQUEST_BASED) * 2);
1746
1747 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
1748 DMEMIT("queue_if_no_path ");
1749 if (m->pg_init_retries)
1750 DMEMIT("pg_init_retries %u ", m->pg_init_retries);
1751 if (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT)
1752 DMEMIT("pg_init_delay_msecs %u ", m->pg_init_delay_msecs);
1753 if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags))
1754 DMEMIT("retain_attached_hw_handler ");
1755 if (m->queue_mode != DM_TYPE_REQUEST_BASED) {
1756 switch(m->queue_mode) {
1757 case DM_TYPE_BIO_BASED:
1758 DMEMIT("queue_mode bio ");
1759 break;
1760 case DM_TYPE_MQ_REQUEST_BASED:
1761 DMEMIT("queue_mode mq ");
1762 break;
1763 }
1764 }
1765 }
1766
1767 if (!m->hw_handler_name || type == STATUSTYPE_INFO)
1768 DMEMIT("0 ");
1769 else
1770 DMEMIT("1 %s ", m->hw_handler_name);
1771
1772 DMEMIT("%u ", m->nr_priority_groups);
1773
1774 if (m->next_pg)
1775 pg_num = m->next_pg->pg_num;
1776 else if (m->current_pg)
1777 pg_num = m->current_pg->pg_num;
1778 else
1779 pg_num = (m->nr_priority_groups ? 1 : 0);
1780
1781 DMEMIT("%u ", pg_num);
1782
1783 switch (type) {
1784 case STATUSTYPE_INFO:
1785 list_for_each_entry(pg, &m->priority_groups, list) {
1786 if (pg->bypassed)
1787 state = 'D'; /* Disabled */
1788 else if (pg == m->current_pg)
1789 state = 'A'; /* Currently Active */
1790 else
1791 state = 'E'; /* Enabled */
1792
1793 DMEMIT("%c ", state);
1794
1795 if (pg->ps.type->status)
1796 sz += pg->ps.type->status(&pg->ps, NULL, type,
1797 result + sz,
1798 maxlen - sz);
1799 else
1800 DMEMIT("0 ");
1801
1802 DMEMIT("%u %u ", pg->nr_pgpaths,
1803 pg->ps.type->info_args);
1804
1805 list_for_each_entry(p, &pg->pgpaths, list) {
1806 DMEMIT("%s %s %u ", p->path.dev->name,
1807 p->is_active ? "A" : "F",
1808 p->fail_count);
1809 if (pg->ps.type->status)
1810 sz += pg->ps.type->status(&pg->ps,
1811 &p->path, type, result + sz,
1812 maxlen - sz);
1813 }
1814 }
1815 break;
1816
1817 case STATUSTYPE_TABLE:
1818 list_for_each_entry(pg, &m->priority_groups, list) {
1819 DMEMIT("%s ", pg->ps.type->name);
1820
1821 if (pg->ps.type->status)
1822 sz += pg->ps.type->status(&pg->ps, NULL, type,
1823 result + sz,
1824 maxlen - sz);
1825 else
1826 DMEMIT("0 ");
1827
1828 DMEMIT("%u %u ", pg->nr_pgpaths,
1829 pg->ps.type->table_args);
1830
1831 list_for_each_entry(p, &pg->pgpaths, list) {
1832 DMEMIT("%s ", p->path.dev->name);
1833 if (pg->ps.type->status)
1834 sz += pg->ps.type->status(&pg->ps,
1835 &p->path, type, result + sz,
1836 maxlen - sz);
1837 }
1838 }
1839 break;
1840 }
1841
1842 spin_unlock_irqrestore(&m->lock, flags);
1843 }
1844
1845 static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
1846 {
1847 int r = -EINVAL;
1848 struct dm_dev *dev;
1849 struct multipath *m = ti->private;
1850 action_fn action;
1851
1852 mutex_lock(&m->work_mutex);
1853
1854 if (dm_suspended(ti)) {
1855 r = -EBUSY;
1856 goto out;
1857 }
1858
1859 if (argc == 1) {
1860 if (!strcasecmp(argv[0], "queue_if_no_path")) {
1861 r = queue_if_no_path(m, true, false);
1862 goto out;
1863 } else if (!strcasecmp(argv[0], "fail_if_no_path")) {
1864 r = queue_if_no_path(m, false, false);
1865 goto out;
1866 }
1867 }
1868
1869 if (argc != 2) {
1870 DMWARN("Invalid multipath message arguments. Expected 2 arguments, got %d.", argc);
1871 goto out;
1872 }
1873
1874 if (!strcasecmp(argv[0], "disable_group")) {
1875 r = bypass_pg_num(m, argv[1], true);
1876 goto out;
1877 } else if (!strcasecmp(argv[0], "enable_group")) {
1878 r = bypass_pg_num(m, argv[1], false);
1879 goto out;
1880 } else if (!strcasecmp(argv[0], "switch_group")) {
1881 r = switch_pg_num(m, argv[1]);
1882 goto out;
1883 } else if (!strcasecmp(argv[0], "reinstate_path"))
1884 action = reinstate_path;
1885 else if (!strcasecmp(argv[0], "fail_path"))
1886 action = fail_path;
1887 else {
1888 DMWARN("Unrecognised multipath message received: %s", argv[0]);
1889 goto out;
1890 }
1891
1892 r = dm_get_device(ti, argv[1], dm_table_get_mode(ti->table), &dev);
1893 if (r) {
1894 DMWARN("message: error getting device %s",
1895 argv[1]);
1896 goto out;
1897 }
1898
1899 r = action_dev(m, dev, action);
1900
1901 dm_put_device(ti, dev);
1902
1903 out:
1904 mutex_unlock(&m->work_mutex);
1905 return r;
1906 }
1907
1908 static int multipath_prepare_ioctl(struct dm_target *ti,
1909 struct block_device **bdev, fmode_t *mode)
1910 {
1911 struct multipath *m = ti->private;
1912 struct pgpath *current_pgpath;
1913 int r;
1914
1915 current_pgpath = lockless_dereference(m->current_pgpath);
1916 if (!current_pgpath)
1917 current_pgpath = choose_pgpath(m, 0);
1918
1919 if (current_pgpath) {
1920 if (!test_bit(MPATHF_QUEUE_IO, &m->flags)) {
1921 *bdev = current_pgpath->path.dev->bdev;
1922 *mode = current_pgpath->path.dev->mode;
1923 r = 0;
1924 } else {
1925 /* pg_init has not started or completed */
1926 r = -ENOTCONN;
1927 }
1928 } else {
1929 /* No path is available */
1930 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
1931 r = -ENOTCONN;
1932 else
1933 r = -EIO;
1934 }
1935
1936 if (r == -ENOTCONN) {
1937 if (!lockless_dereference(m->current_pg)) {
1938 /* Path status changed, redo selection */
1939 (void) choose_pgpath(m, 0);
1940 }
1941 if (test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
1942 pg_init_all_paths(m);
1943 dm_table_run_md_queue_async(m->ti->table);
1944 process_queued_io_list(m);
1945 }
1946
1947 /*
1948 * Only pass ioctls through if the device sizes match exactly.
1949 */
1950 if (!r && ti->len != i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT)
1951 return 1;
1952 return r;
1953 }
1954
1955 static int multipath_iterate_devices(struct dm_target *ti,
1956 iterate_devices_callout_fn fn, void *data)
1957 {
1958 struct multipath *m = ti->private;
1959 struct priority_group *pg;
1960 struct pgpath *p;
1961 int ret = 0;
1962
1963 list_for_each_entry(pg, &m->priority_groups, list) {
1964 list_for_each_entry(p, &pg->pgpaths, list) {
1965 ret = fn(ti, p->path.dev, ti->begin, ti->len, data);
1966 if (ret)
1967 goto out;
1968 }
1969 }
1970
1971 out:
1972 return ret;
1973 }
1974
1975 static int pgpath_busy(struct pgpath *pgpath)
1976 {
1977 struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
1978
1979 return blk_lld_busy(q);
1980 }
1981
1982 /*
1983 * We return "busy", only when we can map I/Os but underlying devices
1984 * are busy (so even if we map I/Os now, the I/Os will wait on
1985 * the underlying queue).
1986 * In other words, if we want to kill I/Os or queue them inside us
1987 * due to map unavailability, we don't return "busy". Otherwise,
1988 * dm core won't give us the I/Os and we can't do what we want.
1989 */
1990 static int multipath_busy(struct dm_target *ti)
1991 {
1992 bool busy = false, has_active = false;
1993 struct multipath *m = ti->private;
1994 struct priority_group *pg, *next_pg;
1995 struct pgpath *pgpath;
1996
1997 /* pg_init in progress */
1998 if (atomic_read(&m->pg_init_in_progress))
1999 return true;
2000
2001 /* no paths available, for blk-mq: rely on IO mapping to delay requeue */
2002 if (!atomic_read(&m->nr_valid_paths) && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
2003 return (m->queue_mode != DM_TYPE_MQ_REQUEST_BASED);
2004
2005 /* Guess which priority_group will be used at next mapping time */
2006 pg = lockless_dereference(m->current_pg);
2007 next_pg = lockless_dereference(m->next_pg);
2008 if (unlikely(!lockless_dereference(m->current_pgpath) && next_pg))
2009 pg = next_pg;
2010
2011 if (!pg) {
2012 /*
2013 * We don't know which pg will be used at next mapping time.
2014 * We don't call choose_pgpath() here to avoid to trigger
2015 * pg_init just by busy checking.
2016 * So we don't know whether underlying devices we will be using
2017 * at next mapping time are busy or not. Just try mapping.
2018 */
2019 return busy;
2020 }
2021
2022 /*
2023 * If there is one non-busy active path at least, the path selector
2024 * will be able to select it. So we consider such a pg as not busy.
2025 */
2026 busy = true;
2027 list_for_each_entry(pgpath, &pg->pgpaths, list) {
2028 if (pgpath->is_active) {
2029 has_active = true;
2030 if (!pgpath_busy(pgpath)) {
2031 busy = false;
2032 break;
2033 }
2034 }
2035 }
2036
2037 if (!has_active) {
2038 /*
2039 * No active path in this pg, so this pg won't be used and
2040 * the current_pg will be changed at next mapping time.
2041 * We need to try mapping to determine it.
2042 */
2043 busy = false;
2044 }
2045
2046 return busy;
2047 }
2048
2049 /*-----------------------------------------------------------------
2050 * Module setup
2051 *---------------------------------------------------------------*/
2052 static struct target_type multipath_target = {
2053 .name = "multipath",
2054 .version = {1, 12, 0},
2055 .features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE,
2056 .module = THIS_MODULE,
2057 .ctr = multipath_ctr,
2058 .dtr = multipath_dtr,
2059 .map_rq = multipath_map,
2060 .clone_and_map_rq = multipath_clone_and_map,
2061 .release_clone_rq = multipath_release_clone,
2062 .rq_end_io = multipath_end_io,
2063 .map = multipath_map_bio,
2064 .end_io = multipath_end_io_bio,
2065 .presuspend = multipath_presuspend,
2066 .postsuspend = multipath_postsuspend,
2067 .resume = multipath_resume,
2068 .status = multipath_status,
2069 .message = multipath_message,
2070 .prepare_ioctl = multipath_prepare_ioctl,
2071 .iterate_devices = multipath_iterate_devices,
2072 .busy = multipath_busy,
2073 };
2074
2075 static int __init dm_multipath_init(void)
2076 {
2077 int r;
2078
2079 /* allocate a slab for the dm_mpath_ios */
2080 _mpio_cache = KMEM_CACHE(dm_mpath_io, 0);
2081 if (!_mpio_cache)
2082 return -ENOMEM;
2083
2084 r = dm_register_target(&multipath_target);
2085 if (r < 0) {
2086 DMERR("request-based register failed %d", r);
2087 r = -EINVAL;
2088 goto bad_register_target;
2089 }
2090
2091 kmultipathd = alloc_workqueue("kmpathd", WQ_MEM_RECLAIM, 0);
2092 if (!kmultipathd) {
2093 DMERR("failed to create workqueue kmpathd");
2094 r = -ENOMEM;
2095 goto bad_alloc_kmultipathd;
2096 }
2097
2098 /*
2099 * A separate workqueue is used to handle the device handlers
2100 * to avoid overloading existing workqueue. Overloading the
2101 * old workqueue would also create a bottleneck in the
2102 * path of the storage hardware device activation.
2103 */
2104 kmpath_handlerd = alloc_ordered_workqueue("kmpath_handlerd",
2105 WQ_MEM_RECLAIM);
2106 if (!kmpath_handlerd) {
2107 DMERR("failed to create workqueue kmpath_handlerd");
2108 r = -ENOMEM;
2109 goto bad_alloc_kmpath_handlerd;
2110 }
2111
2112 return 0;
2113
2114 bad_alloc_kmpath_handlerd:
2115 destroy_workqueue(kmultipathd);
2116 bad_alloc_kmultipathd:
2117 dm_unregister_target(&multipath_target);
2118 bad_register_target:
2119 kmem_cache_destroy(_mpio_cache);
2120
2121 return r;
2122 }
2123
2124 static void __exit dm_multipath_exit(void)
2125 {
2126 destroy_workqueue(kmpath_handlerd);
2127 destroy_workqueue(kmultipathd);
2128
2129 dm_unregister_target(&multipath_target);
2130 kmem_cache_destroy(_mpio_cache);
2131 }
2132
2133 module_init(dm_multipath_init);
2134 module_exit(dm_multipath_exit);
2135
2136 MODULE_DESCRIPTION(DM_NAME " multipath target");
2137 MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
2138 MODULE_LICENSE("GPL");
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