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