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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-path-selector.h"
11#include "dm-uevent.h"
12
13#include <linux/ctype.h>
14#include <linux/init.h>
15#include <linux/mempool.h>
16#include <linux/module.h>
17#include <linux/pagemap.h>
18#include <linux/slab.h>
19#include <linux/time.h>
20#include <linux/workqueue.h>
21#include <linux/delay.h>
22#include <scsi/scsi_dh.h>
23#include <linux/atomic.h>
24
25#define DM_MSG_PREFIX "multipath"
26#define DM_PG_INIT_DELAY_MSECS 2000
27#define DM_PG_INIT_DELAY_DEFAULT ((unsigned) -1)
28
29/* Path properties */
30struct pgpath {
31 struct list_head list;
32
33 struct priority_group *pg; /* Owning PG */
34 unsigned is_active; /* Path status */
35 unsigned fail_count; /* Cumulative failure count */
36
37 struct dm_path path;
38 struct delayed_work activate_path;
39};
40
41#define path_to_pgpath(__pgp) container_of((__pgp), struct pgpath, path)
42
43/*
44 * Paths are grouped into Priority Groups and numbered from 1 upwards.
45 * Each has a path selector which controls which path gets used.
46 */
47struct priority_group {
48 struct list_head list;
49
50 struct multipath *m; /* Owning multipath instance */
51 struct path_selector ps;
52
53 unsigned pg_num; /* Reference number */
54 unsigned bypassed; /* Temporarily bypass this PG? */
55
56 unsigned nr_pgpaths; /* Number of paths in PG */
57 struct list_head pgpaths;
58};
59
60/* Multipath context */
61struct multipath {
62 struct list_head list;
63 struct dm_target *ti;
64
65 const char *hw_handler_name;
66 char *hw_handler_params;
67
68 spinlock_t lock;
69
70 unsigned nr_priority_groups;
71 struct list_head priority_groups;
72
73 wait_queue_head_t pg_init_wait; /* Wait for pg_init completion */
74
75 unsigned pg_init_required; /* pg_init needs calling? */
76 unsigned pg_init_in_progress; /* Only one pg_init allowed at once */
77 unsigned pg_init_delay_retry; /* Delay pg_init retry? */
78
79 unsigned nr_valid_paths; /* Total number of usable paths */
80 struct pgpath *current_pgpath;
81 struct priority_group *current_pg;
82 struct priority_group *next_pg; /* Switch to this PG if set */
83 unsigned repeat_count; /* I/Os left before calling PS again */
84
85 unsigned queue_io:1; /* Must we queue all I/O? */
86 unsigned queue_if_no_path:1; /* Queue I/O if last path fails? */
87 unsigned saved_queue_if_no_path:1; /* Saved state during suspension */
88
89 unsigned pg_init_retries; /* Number of times to retry pg_init */
90 unsigned pg_init_count; /* Number of times pg_init called */
91 unsigned pg_init_delay_msecs; /* Number of msecs before pg_init retry */
92
93 unsigned queue_size;
94 struct work_struct process_queued_ios;
95 struct list_head queued_ios;
96
97 struct work_struct trigger_event;
98
99 /*
100 * We must use a mempool of dm_mpath_io structs so that we
101 * can resubmit bios on error.
102 */
103 mempool_t *mpio_pool;
104
105 struct mutex work_mutex;
106};
107
108/*
109 * Context information attached to each bio we process.
110 */
111struct dm_mpath_io {
112 struct pgpath *pgpath;
113 size_t nr_bytes;
114};
115
116typedef int (*action_fn) (struct pgpath *pgpath);
117
118#define MIN_IOS 256 /* Mempool size */
119
120static struct kmem_cache *_mpio_cache;
121
122static struct workqueue_struct *kmultipathd, *kmpath_handlerd;
123static void process_queued_ios(struct work_struct *work);
124static void trigger_event(struct work_struct *work);
125static void activate_path(struct work_struct *work);
126
127
128/*-----------------------------------------------
129 * Allocation routines
130 *-----------------------------------------------*/
131
132static struct pgpath *alloc_pgpath(void)
133{
134 struct pgpath *pgpath = kzalloc(sizeof(*pgpath), GFP_KERNEL);
135
136 if (pgpath) {
137 pgpath->is_active = 1;
138 INIT_DELAYED_WORK(&pgpath->activate_path, activate_path);
139 }
140
141 return pgpath;
142}
143
144static void free_pgpath(struct pgpath *pgpath)
145{
146 kfree(pgpath);
147}
148
149static struct priority_group *alloc_priority_group(void)
150{
151 struct priority_group *pg;
152
153 pg = kzalloc(sizeof(*pg), GFP_KERNEL);
154
155 if (pg)
156 INIT_LIST_HEAD(&pg->pgpaths);
157
158 return pg;
159}
160
161static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti)
162{
163 struct pgpath *pgpath, *tmp;
164 struct multipath *m = ti->private;
165
166 list_for_each_entry_safe(pgpath, tmp, pgpaths, list) {
167 list_del(&pgpath->list);
168 if (m->hw_handler_name)
169 scsi_dh_detach(bdev_get_queue(pgpath->path.dev->bdev));
170 dm_put_device(ti, pgpath->path.dev);
171 free_pgpath(pgpath);
172 }
173}
174
175static void free_priority_group(struct priority_group *pg,
176 struct dm_target *ti)
177{
178 struct path_selector *ps = &pg->ps;
179
180 if (ps->type) {
181 ps->type->destroy(ps);
182 dm_put_path_selector(ps->type);
183 }
184
185 free_pgpaths(&pg->pgpaths, ti);
186 kfree(pg);
187}
188
189static struct multipath *alloc_multipath(struct dm_target *ti)
190{
191 struct multipath *m;
192
193 m = kzalloc(sizeof(*m), GFP_KERNEL);
194 if (m) {
195 INIT_LIST_HEAD(&m->priority_groups);
196 INIT_LIST_HEAD(&m->queued_ios);
197 spin_lock_init(&m->lock);
198 m->queue_io = 1;
199 m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT;
200 INIT_WORK(&m->process_queued_ios, process_queued_ios);
201 INIT_WORK(&m->trigger_event, trigger_event);
202 init_waitqueue_head(&m->pg_init_wait);
203 mutex_init(&m->work_mutex);
204 m->mpio_pool = mempool_create_slab_pool(MIN_IOS, _mpio_cache);
205 if (!m->mpio_pool) {
206 kfree(m);
207 return NULL;
208 }
209 m->ti = ti;
210 ti->private = m;
211 }
212
213 return m;
214}
215
216static void free_multipath(struct multipath *m)
217{
218 struct priority_group *pg, *tmp;
219
220 list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) {
221 list_del(&pg->list);
222 free_priority_group(pg, m->ti);
223 }
224
225 kfree(m->hw_handler_name);
226 kfree(m->hw_handler_params);
227 mempool_destroy(m->mpio_pool);
228 kfree(m);
229}
230
231static int set_mapinfo(struct multipath *m, union map_info *info)
232{
233 struct dm_mpath_io *mpio;
234
235 mpio = mempool_alloc(m->mpio_pool, GFP_ATOMIC);
236 if (!mpio)
237 return -ENOMEM;
238
239 memset(mpio, 0, sizeof(*mpio));
240 info->ptr = mpio;
241
242 return 0;
243}
244
245static void clear_mapinfo(struct multipath *m, union map_info *info)
246{
247 struct dm_mpath_io *mpio = info->ptr;
248
249 info->ptr = NULL;
250 mempool_free(mpio, m->mpio_pool);
251}
252
253/*-----------------------------------------------
254 * Path selection
255 *-----------------------------------------------*/
256
257static void __pg_init_all_paths(struct multipath *m)
258{
259 struct pgpath *pgpath;
260 unsigned long pg_init_delay = 0;
261
262 m->pg_init_count++;
263 m->pg_init_required = 0;
264 if (m->pg_init_delay_retry)
265 pg_init_delay = msecs_to_jiffies(m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT ?
266 m->pg_init_delay_msecs : DM_PG_INIT_DELAY_MSECS);
267 list_for_each_entry(pgpath, &m->current_pg->pgpaths, list) {
268 /* Skip failed paths */
269 if (!pgpath->is_active)
270 continue;
271 if (queue_delayed_work(kmpath_handlerd, &pgpath->activate_path,
272 pg_init_delay))
273 m->pg_init_in_progress++;
274 }
275}
276
277static void __switch_pg(struct multipath *m, struct pgpath *pgpath)
278{
279 m->current_pg = pgpath->pg;
280
281 /* Must we initialise the PG first, and queue I/O till it's ready? */
282 if (m->hw_handler_name) {
283 m->pg_init_required = 1;
284 m->queue_io = 1;
285 } else {
286 m->pg_init_required = 0;
287 m->queue_io = 0;
288 }
289
290 m->pg_init_count = 0;
291}
292
293static int __choose_path_in_pg(struct multipath *m, struct priority_group *pg,
294 size_t nr_bytes)
295{
296 struct dm_path *path;
297
298 path = pg->ps.type->select_path(&pg->ps, &m->repeat_count, nr_bytes);
299 if (!path)
300 return -ENXIO;
301
302 m->current_pgpath = path_to_pgpath(path);
303
304 if (m->current_pg != pg)
305 __switch_pg(m, m->current_pgpath);
306
307 return 0;
308}
309
310static void __choose_pgpath(struct multipath *m, size_t nr_bytes)
311{
312 struct priority_group *pg;
313 unsigned bypassed = 1;
314
315 if (!m->nr_valid_paths)
316 goto failed;
317
318 /* Were we instructed to switch PG? */
319 if (m->next_pg) {
320 pg = m->next_pg;
321 m->next_pg = NULL;
322 if (!__choose_path_in_pg(m, pg, nr_bytes))
323 return;
324 }
325
326 /* Don't change PG until it has no remaining paths */
327 if (m->current_pg && !__choose_path_in_pg(m, m->current_pg, nr_bytes))
328 return;
329
330 /*
331 * Loop through priority groups until we find a valid path.
332 * First time we skip PGs marked 'bypassed'.
333 * Second time we only try the ones we skipped, but set
334 * pg_init_delay_retry so we do not hammer controllers.
335 */
336 do {
337 list_for_each_entry(pg, &m->priority_groups, list) {
338 if (pg->bypassed == bypassed)
339 continue;
340 if (!__choose_path_in_pg(m, pg, nr_bytes)) {
341 if (!bypassed)
342 m->pg_init_delay_retry = 1;
343 return;
344 }
345 }
346 } while (bypassed--);
347
348failed:
349 m->current_pgpath = NULL;
350 m->current_pg = NULL;
351}
352
353/*
354 * Check whether bios must be queued in the device-mapper core rather
355 * than here in the target.
356 *
357 * m->lock must be held on entry.
358 *
359 * If m->queue_if_no_path and m->saved_queue_if_no_path hold the
360 * same value then we are not between multipath_presuspend()
361 * and multipath_resume() calls and we have no need to check
362 * for the DMF_NOFLUSH_SUSPENDING flag.
363 */
364static int __must_push_back(struct multipath *m)
365{
366 return (m->queue_if_no_path != m->saved_queue_if_no_path &&
367 dm_noflush_suspending(m->ti));
368}
369
370static int map_io(struct multipath *m, struct request *clone,
371 union map_info *map_context, unsigned was_queued)
372{
373 int r = DM_MAPIO_REMAPPED;
374 size_t nr_bytes = blk_rq_bytes(clone);
375 unsigned long flags;
376 struct pgpath *pgpath;
377 struct block_device *bdev;
378 struct dm_mpath_io *mpio = map_context->ptr;
379
380 spin_lock_irqsave(&m->lock, flags);
381
382 /* Do we need to select a new pgpath? */
383 if (!m->current_pgpath ||
384 (!m->queue_io && (m->repeat_count && --m->repeat_count == 0)))
385 __choose_pgpath(m, nr_bytes);
386
387 pgpath = m->current_pgpath;
388
389 if (was_queued)
390 m->queue_size--;
391
392 if ((pgpath && m->queue_io) ||
393 (!pgpath && m->queue_if_no_path)) {
394 /* Queue for the daemon to resubmit */
395 list_add_tail(&clone->queuelist, &m->queued_ios);
396 m->queue_size++;
397 if ((m->pg_init_required && !m->pg_init_in_progress) ||
398 !m->queue_io)
399 queue_work(kmultipathd, &m->process_queued_ios);
400 pgpath = NULL;
401 r = DM_MAPIO_SUBMITTED;
402 } else if (pgpath) {
403 bdev = pgpath->path.dev->bdev;
404 clone->q = bdev_get_queue(bdev);
405 clone->rq_disk = bdev->bd_disk;
406 } else if (__must_push_back(m))
407 r = DM_MAPIO_REQUEUE;
408 else
409 r = -EIO; /* Failed */
410
411 mpio->pgpath = pgpath;
412 mpio->nr_bytes = nr_bytes;
413
414 if (r == DM_MAPIO_REMAPPED && pgpath->pg->ps.type->start_io)
415 pgpath->pg->ps.type->start_io(&pgpath->pg->ps, &pgpath->path,
416 nr_bytes);
417
418 spin_unlock_irqrestore(&m->lock, flags);
419
420 return r;
421}
422
423/*
424 * If we run out of usable paths, should we queue I/O or error it?
425 */
426static int queue_if_no_path(struct multipath *m, unsigned queue_if_no_path,
427 unsigned save_old_value)
428{
429 unsigned long flags;
430
431 spin_lock_irqsave(&m->lock, flags);
432
433 if (save_old_value)
434 m->saved_queue_if_no_path = m->queue_if_no_path;
435 else
436 m->saved_queue_if_no_path = queue_if_no_path;
437 m->queue_if_no_path = queue_if_no_path;
438 if (!m->queue_if_no_path && m->queue_size)
439 queue_work(kmultipathd, &m->process_queued_ios);
440
441 spin_unlock_irqrestore(&m->lock, flags);
442
443 return 0;
444}
445
446/*-----------------------------------------------------------------
447 * The multipath daemon is responsible for resubmitting queued ios.
448 *---------------------------------------------------------------*/
449
450static void dispatch_queued_ios(struct multipath *m)
451{
452 int r;
453 unsigned long flags;
454 union map_info *info;
455 struct request *clone, *n;
456 LIST_HEAD(cl);
457
458 spin_lock_irqsave(&m->lock, flags);
459 list_splice_init(&m->queued_ios, &cl);
460 spin_unlock_irqrestore(&m->lock, flags);
461
462 list_for_each_entry_safe(clone, n, &cl, queuelist) {
463 list_del_init(&clone->queuelist);
464
465 info = dm_get_rq_mapinfo(clone);
466
467 r = map_io(m, clone, info, 1);
468 if (r < 0) {
469 clear_mapinfo(m, info);
470 dm_kill_unmapped_request(clone, r);
471 } else if (r == DM_MAPIO_REMAPPED)
472 dm_dispatch_request(clone);
473 else if (r == DM_MAPIO_REQUEUE) {
474 clear_mapinfo(m, info);
475 dm_requeue_unmapped_request(clone);
476 }
477 }
478}
479
480static void process_queued_ios(struct work_struct *work)
481{
482 struct multipath *m =
483 container_of(work, struct multipath, process_queued_ios);
484 struct pgpath *pgpath = NULL;
485 unsigned must_queue = 1;
486 unsigned long flags;
487
488 spin_lock_irqsave(&m->lock, flags);
489
490 if (!m->current_pgpath)
491 __choose_pgpath(m, 0);
492
493 pgpath = m->current_pgpath;
494
495 if ((pgpath && !m->queue_io) ||
496 (!pgpath && !m->queue_if_no_path))
497 must_queue = 0;
498
499 if (m->pg_init_required && !m->pg_init_in_progress && pgpath)
500 __pg_init_all_paths(m);
501
502 spin_unlock_irqrestore(&m->lock, flags);
503 if (!must_queue)
504 dispatch_queued_ios(m);
505}
506
507/*
508 * An event is triggered whenever a path is taken out of use.
509 * Includes path failure and PG bypass.
510 */
511static void trigger_event(struct work_struct *work)
512{
513 struct multipath *m =
514 container_of(work, struct multipath, trigger_event);
515
516 dm_table_event(m->ti->table);
517}
518
519/*-----------------------------------------------------------------
520 * Constructor/argument parsing:
521 * <#multipath feature args> [<arg>]*
522 * <#hw_handler args> [hw_handler [<arg>]*]
523 * <#priority groups>
524 * <initial priority group>
525 * [<selector> <#selector args> [<arg>]*
526 * <#paths> <#per-path selector args>
527 * [<path> [<arg>]* ]+ ]+
528 *---------------------------------------------------------------*/
529static int parse_path_selector(struct dm_arg_set *as, struct priority_group *pg,
530 struct dm_target *ti)
531{
532 int r;
533 struct path_selector_type *pst;
534 unsigned ps_argc;
535
536 static struct dm_arg _args[] = {
537 {0, 1024, "invalid number of path selector args"},
538 };
539
540 pst = dm_get_path_selector(dm_shift_arg(as));
541 if (!pst) {
542 ti->error = "unknown path selector type";
543 return -EINVAL;
544 }
545
546 r = dm_read_arg_group(_args, as, &ps_argc, &ti->error);
547 if (r) {
548 dm_put_path_selector(pst);
549 return -EINVAL;
550 }
551
552 r = pst->create(&pg->ps, ps_argc, as->argv);
553 if (r) {
554 dm_put_path_selector(pst);
555 ti->error = "path selector constructor failed";
556 return r;
557 }
558
559 pg->ps.type = pst;
560 dm_consume_args(as, ps_argc);
561
562 return 0;
563}
564
565static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps,
566 struct dm_target *ti)
567{
568 int r;
569 struct pgpath *p;
570 struct multipath *m = ti->private;
571
572 /* we need at least a path arg */
573 if (as->argc < 1) {
574 ti->error = "no device given";
575 return ERR_PTR(-EINVAL);
576 }
577
578 p = alloc_pgpath();
579 if (!p)
580 return ERR_PTR(-ENOMEM);
581
582 r = dm_get_device(ti, dm_shift_arg(as), dm_table_get_mode(ti->table),
583 &p->path.dev);
584 if (r) {
585 ti->error = "error getting device";
586 goto bad;
587 }
588
589 if (m->hw_handler_name) {
590 struct request_queue *q = bdev_get_queue(p->path.dev->bdev);
591
592 r = scsi_dh_attach(q, m->hw_handler_name);
593 if (r == -EBUSY) {
594 /*
595 * Already attached to different hw_handler,
596 * try to reattach with correct one.
597 */
598 scsi_dh_detach(q);
599 r = scsi_dh_attach(q, m->hw_handler_name);
600 }
601
602 if (r < 0) {
603 ti->error = "error attaching hardware handler";
604 dm_put_device(ti, p->path.dev);
605 goto bad;
606 }
607
608 if (m->hw_handler_params) {
609 r = scsi_dh_set_params(q, m->hw_handler_params);
610 if (r < 0) {
611 ti->error = "unable to set hardware "
612 "handler parameters";
613 scsi_dh_detach(q);
614 dm_put_device(ti, p->path.dev);
615 goto bad;
616 }
617 }
618 }
619
620 r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
621 if (r) {
622 dm_put_device(ti, p->path.dev);
623 goto bad;
624 }
625
626 return p;
627
628 bad:
629 free_pgpath(p);
630 return ERR_PTR(r);
631}
632
633static struct priority_group *parse_priority_group(struct dm_arg_set *as,
634 struct multipath *m)
635{
636 static struct dm_arg _args[] = {
637 {1, 1024, "invalid number of paths"},
638 {0, 1024, "invalid number of selector args"}
639 };
640
641 int r;
642 unsigned i, nr_selector_args, nr_args;
643 struct priority_group *pg;
644 struct dm_target *ti = m->ti;
645
646 if (as->argc < 2) {
647 as->argc = 0;
648 ti->error = "not enough priority group arguments";
649 return ERR_PTR(-EINVAL);
650 }
651
652 pg = alloc_priority_group();
653 if (!pg) {
654 ti->error = "couldn't allocate priority group";
655 return ERR_PTR(-ENOMEM);
656 }
657 pg->m = m;
658
659 r = parse_path_selector(as, pg, ti);
660 if (r)
661 goto bad;
662
663 /*
664 * read the paths
665 */
666 r = dm_read_arg(_args, as, &pg->nr_pgpaths, &ti->error);
667 if (r)
668 goto bad;
669
670 r = dm_read_arg(_args + 1, as, &nr_selector_args, &ti->error);
671 if (r)
672 goto bad;
673
674 nr_args = 1 + nr_selector_args;
675 for (i = 0; i < pg->nr_pgpaths; i++) {
676 struct pgpath *pgpath;
677 struct dm_arg_set path_args;
678
679 if (as->argc < nr_args) {
680 ti->error = "not enough path parameters";
681 r = -EINVAL;
682 goto bad;
683 }
684
685 path_args.argc = nr_args;
686 path_args.argv = as->argv;
687
688 pgpath = parse_path(&path_args, &pg->ps, ti);
689 if (IS_ERR(pgpath)) {
690 r = PTR_ERR(pgpath);
691 goto bad;
692 }
693
694 pgpath->pg = pg;
695 list_add_tail(&pgpath->list, &pg->pgpaths);
696 dm_consume_args(as, nr_args);
697 }
698
699 return pg;
700
701 bad:
702 free_priority_group(pg, ti);
703 return ERR_PTR(r);
704}
705
706static int parse_hw_handler(struct dm_arg_set *as, struct multipath *m)
707{
708 unsigned hw_argc;
709 int ret;
710 struct dm_target *ti = m->ti;
711
712 static struct dm_arg _args[] = {
713 {0, 1024, "invalid number of hardware handler args"},
714 };
715
716 if (dm_read_arg_group(_args, as, &hw_argc, &ti->error))
717 return -EINVAL;
718
719 if (!hw_argc)
720 return 0;
721
722 m->hw_handler_name = kstrdup(dm_shift_arg(as), GFP_KERNEL);
723 if (!try_then_request_module(scsi_dh_handler_exist(m->hw_handler_name),
724 "scsi_dh_%s", m->hw_handler_name)) {
725 ti->error = "unknown hardware handler type";
726 ret = -EINVAL;
727 goto fail;
728 }
729
730 if (hw_argc > 1) {
731 char *p;
732 int i, j, len = 4;
733
734 for (i = 0; i <= hw_argc - 2; i++)
735 len += strlen(as->argv[i]) + 1;
736 p = m->hw_handler_params = kzalloc(len, GFP_KERNEL);
737 if (!p) {
738 ti->error = "memory allocation failed";
739 ret = -ENOMEM;
740 goto fail;
741 }
742 j = sprintf(p, "%d", hw_argc - 1);
743 for (i = 0, p+=j+1; i <= hw_argc - 2; i++, p+=j+1)
744 j = sprintf(p, "%s", as->argv[i]);
745 }
746 dm_consume_args(as, hw_argc - 1);
747
748 return 0;
749fail:
750 kfree(m->hw_handler_name);
751 m->hw_handler_name = NULL;
752 return ret;
753}
754
755static int parse_features(struct dm_arg_set *as, struct multipath *m)
756{
757 int r;
758 unsigned argc;
759 struct dm_target *ti = m->ti;
760 const char *arg_name;
761
762 static struct dm_arg _args[] = {
763 {0, 5, "invalid number of feature args"},
764 {1, 50, "pg_init_retries must be between 1 and 50"},
765 {0, 60000, "pg_init_delay_msecs must be between 0 and 60000"},
766 };
767
768 r = dm_read_arg_group(_args, as, &argc, &ti->error);
769 if (r)
770 return -EINVAL;
771
772 if (!argc)
773 return 0;
774
775 do {
776 arg_name = dm_shift_arg(as);
777 argc--;
778
779 if (!strcasecmp(arg_name, "queue_if_no_path")) {
780 r = queue_if_no_path(m, 1, 0);
781 continue;
782 }
783
784 if (!strcasecmp(arg_name, "pg_init_retries") &&
785 (argc >= 1)) {
786 r = dm_read_arg(_args + 1, as, &m->pg_init_retries, &ti->error);
787 argc--;
788 continue;
789 }
790
791 if (!strcasecmp(arg_name, "pg_init_delay_msecs") &&
792 (argc >= 1)) {
793 r = dm_read_arg(_args + 2, as, &m->pg_init_delay_msecs, &ti->error);
794 argc--;
795 continue;
796 }
797
798 ti->error = "Unrecognised multipath feature request";
799 r = -EINVAL;
800 } while (argc && !r);
801
802 return r;
803}
804
805static int multipath_ctr(struct dm_target *ti, unsigned int argc,
806 char **argv)
807{
808 /* target arguments */
809 static struct dm_arg _args[] = {
810 {0, 1024, "invalid number of priority groups"},
811 {0, 1024, "invalid initial priority group number"},
812 };
813
814 int r;
815 struct multipath *m;
816 struct dm_arg_set as;
817 unsigned pg_count = 0;
818 unsigned next_pg_num;
819
820 as.argc = argc;
821 as.argv = argv;
822
823 m = alloc_multipath(ti);
824 if (!m) {
825 ti->error = "can't allocate multipath";
826 return -EINVAL;
827 }
828
829 r = parse_features(&as, m);
830 if (r)
831 goto bad;
832
833 r = parse_hw_handler(&as, m);
834 if (r)
835 goto bad;
836
837 r = dm_read_arg(_args, &as, &m->nr_priority_groups, &ti->error);
838 if (r)
839 goto bad;
840
841 r = dm_read_arg(_args + 1, &as, &next_pg_num, &ti->error);
842 if (r)
843 goto bad;
844
845 if ((!m->nr_priority_groups && next_pg_num) ||
846 (m->nr_priority_groups && !next_pg_num)) {
847 ti->error = "invalid initial priority group";
848 r = -EINVAL;
849 goto bad;
850 }
851
852 /* parse the priority groups */
853 while (as.argc) {
854 struct priority_group *pg;
855
856 pg = parse_priority_group(&as, m);
857 if (IS_ERR(pg)) {
858 r = PTR_ERR(pg);
859 goto bad;
860 }
861
862 m->nr_valid_paths += pg->nr_pgpaths;
863 list_add_tail(&pg->list, &m->priority_groups);
864 pg_count++;
865 pg->pg_num = pg_count;
866 if (!--next_pg_num)
867 m->next_pg = pg;
868 }
869
870 if (pg_count != m->nr_priority_groups) {
871 ti->error = "priority group count mismatch";
872 r = -EINVAL;
873 goto bad;
874 }
875
876 ti->num_flush_requests = 1;
877 ti->num_discard_requests = 1;
878
879 return 0;
880
881 bad:
882 free_multipath(m);
883 return r;
884}
885
886static void multipath_wait_for_pg_init_completion(struct multipath *m)
887{
888 DECLARE_WAITQUEUE(wait, current);
889 unsigned long flags;
890
891 add_wait_queue(&m->pg_init_wait, &wait);
892
893 while (1) {
894 set_current_state(TASK_UNINTERRUPTIBLE);
895
896 spin_lock_irqsave(&m->lock, flags);
897 if (!m->pg_init_in_progress) {
898 spin_unlock_irqrestore(&m->lock, flags);
899 break;
900 }
901 spin_unlock_irqrestore(&m->lock, flags);
902
903 io_schedule();
904 }
905 set_current_state(TASK_RUNNING);
906
907 remove_wait_queue(&m->pg_init_wait, &wait);
908}
909
910static void flush_multipath_work(struct multipath *m)
911{
912 flush_workqueue(kmpath_handlerd);
913 multipath_wait_for_pg_init_completion(m);
914 flush_workqueue(kmultipathd);
915 flush_work_sync(&m->trigger_event);
916}
917
918static void multipath_dtr(struct dm_target *ti)
919{
920 struct multipath *m = ti->private;
921
922 flush_multipath_work(m);
923 free_multipath(m);
924}
925
926/*
927 * Map cloned requests
928 */
929static int multipath_map(struct dm_target *ti, struct request *clone,
930 union map_info *map_context)
931{
932 int r;
933 struct multipath *m = (struct multipath *) ti->private;
934
935 if (set_mapinfo(m, map_context) < 0)
936 /* ENOMEM, requeue */
937 return DM_MAPIO_REQUEUE;
938
939 clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
940 r = map_io(m, clone, map_context, 0);
941 if (r < 0 || r == DM_MAPIO_REQUEUE)
942 clear_mapinfo(m, map_context);
943
944 return r;
945}
946
947/*
948 * Take a path out of use.
949 */
950static int fail_path(struct pgpath *pgpath)
951{
952 unsigned long flags;
953 struct multipath *m = pgpath->pg->m;
954
955 spin_lock_irqsave(&m->lock, flags);
956
957 if (!pgpath->is_active)
958 goto out;
959
960 DMWARN("Failing path %s.", pgpath->path.dev->name);
961
962 pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
963 pgpath->is_active = 0;
964 pgpath->fail_count++;
965
966 m->nr_valid_paths--;
967
968 if (pgpath == m->current_pgpath)
969 m->current_pgpath = NULL;
970
971 dm_path_uevent(DM_UEVENT_PATH_FAILED, m->ti,
972 pgpath->path.dev->name, m->nr_valid_paths);
973
974 schedule_work(&m->trigger_event);
975
976out:
977 spin_unlock_irqrestore(&m->lock, flags);
978
979 return 0;
980}
981
982/*
983 * Reinstate a previously-failed path
984 */
985static int reinstate_path(struct pgpath *pgpath)
986{
987 int r = 0;
988 unsigned long flags;
989 struct multipath *m = pgpath->pg->m;
990
991 spin_lock_irqsave(&m->lock, flags);
992
993 if (pgpath->is_active)
994 goto out;
995
996 if (!pgpath->pg->ps.type->reinstate_path) {
997 DMWARN("Reinstate path not supported by path selector %s",
998 pgpath->pg->ps.type->name);
999 r = -EINVAL;
1000 goto out;
1001 }
1002
1003 r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
1004 if (r)
1005 goto out;
1006
1007 pgpath->is_active = 1;
1008
1009 if (!m->nr_valid_paths++ && m->queue_size) {
1010 m->current_pgpath = NULL;
1011 queue_work(kmultipathd, &m->process_queued_ios);
1012 } else if (m->hw_handler_name && (m->current_pg == pgpath->pg)) {
1013 if (queue_work(kmpath_handlerd, &pgpath->activate_path.work))
1014 m->pg_init_in_progress++;
1015 }
1016
1017 dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti,
1018 pgpath->path.dev->name, m->nr_valid_paths);
1019
1020 schedule_work(&m->trigger_event);
1021
1022out:
1023 spin_unlock_irqrestore(&m->lock, flags);
1024
1025 return r;
1026}
1027
1028/*
1029 * Fail or reinstate all paths that match the provided struct dm_dev.
1030 */
1031static int action_dev(struct multipath *m, struct dm_dev *dev,
1032 action_fn action)
1033{
1034 int r = -EINVAL;
1035 struct pgpath *pgpath;
1036 struct priority_group *pg;
1037
1038 list_for_each_entry(pg, &m->priority_groups, list) {
1039 list_for_each_entry(pgpath, &pg->pgpaths, list) {
1040 if (pgpath->path.dev == dev)
1041 r = action(pgpath);
1042 }
1043 }
1044
1045 return r;
1046}
1047
1048/*
1049 * Temporarily try to avoid having to use the specified PG
1050 */
1051static void bypass_pg(struct multipath *m, struct priority_group *pg,
1052 int bypassed)
1053{
1054 unsigned long flags;
1055
1056 spin_lock_irqsave(&m->lock, flags);
1057
1058 pg->bypassed = bypassed;
1059 m->current_pgpath = NULL;
1060 m->current_pg = NULL;
1061
1062 spin_unlock_irqrestore(&m->lock, flags);
1063
1064 schedule_work(&m->trigger_event);
1065}
1066
1067/*
1068 * Switch to using the specified PG from the next I/O that gets mapped
1069 */
1070static int switch_pg_num(struct multipath *m, const char *pgstr)
1071{
1072 struct priority_group *pg;
1073 unsigned pgnum;
1074 unsigned long flags;
1075 char dummy;
1076
1077 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1078 (pgnum > m->nr_priority_groups)) {
1079 DMWARN("invalid PG number supplied to switch_pg_num");
1080 return -EINVAL;
1081 }
1082
1083 spin_lock_irqsave(&m->lock, flags);
1084 list_for_each_entry(pg, &m->priority_groups, list) {
1085 pg->bypassed = 0;
1086 if (--pgnum)
1087 continue;
1088
1089 m->current_pgpath = NULL;
1090 m->current_pg = NULL;
1091 m->next_pg = pg;
1092 }
1093 spin_unlock_irqrestore(&m->lock, flags);
1094
1095 schedule_work(&m->trigger_event);
1096 return 0;
1097}
1098
1099/*
1100 * Set/clear bypassed status of a PG.
1101 * PGs are numbered upwards from 1 in the order they were declared.
1102 */
1103static int bypass_pg_num(struct multipath *m, const char *pgstr, int bypassed)
1104{
1105 struct priority_group *pg;
1106 unsigned pgnum;
1107 char dummy;
1108
1109 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1110 (pgnum > m->nr_priority_groups)) {
1111 DMWARN("invalid PG number supplied to bypass_pg");
1112 return -EINVAL;
1113 }
1114
1115 list_for_each_entry(pg, &m->priority_groups, list) {
1116 if (!--pgnum)
1117 break;
1118 }
1119
1120 bypass_pg(m, pg, bypassed);
1121 return 0;
1122}
1123
1124/*
1125 * Should we retry pg_init immediately?
1126 */
1127static int pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath)
1128{
1129 unsigned long flags;
1130 int limit_reached = 0;
1131
1132 spin_lock_irqsave(&m->lock, flags);
1133
1134 if (m->pg_init_count <= m->pg_init_retries)
1135 m->pg_init_required = 1;
1136 else
1137 limit_reached = 1;
1138
1139 spin_unlock_irqrestore(&m->lock, flags);
1140
1141 return limit_reached;
1142}
1143
1144static void pg_init_done(void *data, int errors)
1145{
1146 struct pgpath *pgpath = data;
1147 struct priority_group *pg = pgpath->pg;
1148 struct multipath *m = pg->m;
1149 unsigned long flags;
1150 unsigned delay_retry = 0;
1151
1152 /* device or driver problems */
1153 switch (errors) {
1154 case SCSI_DH_OK:
1155 break;
1156 case SCSI_DH_NOSYS:
1157 if (!m->hw_handler_name) {
1158 errors = 0;
1159 break;
1160 }
1161 DMERR("Could not failover the device: Handler scsi_dh_%s "
1162 "Error %d.", m->hw_handler_name, errors);
1163 /*
1164 * Fail path for now, so we do not ping pong
1165 */
1166 fail_path(pgpath);
1167 break;
1168 case SCSI_DH_DEV_TEMP_BUSY:
1169 /*
1170 * Probably doing something like FW upgrade on the
1171 * controller so try the other pg.
1172 */
1173 bypass_pg(m, pg, 1);
1174 break;
1175 case SCSI_DH_RETRY:
1176 /* Wait before retrying. */
1177 delay_retry = 1;
1178 case SCSI_DH_IMM_RETRY:
1179 case SCSI_DH_RES_TEMP_UNAVAIL:
1180 if (pg_init_limit_reached(m, pgpath))
1181 fail_path(pgpath);
1182 errors = 0;
1183 break;
1184 default:
1185 /*
1186 * We probably do not want to fail the path for a device
1187 * error, but this is what the old dm did. In future
1188 * patches we can do more advanced handling.
1189 */
1190 fail_path(pgpath);
1191 }
1192
1193 spin_lock_irqsave(&m->lock, flags);
1194 if (errors) {
1195 if (pgpath == m->current_pgpath) {
1196 DMERR("Could not failover device. Error %d.", errors);
1197 m->current_pgpath = NULL;
1198 m->current_pg = NULL;
1199 }
1200 } else if (!m->pg_init_required)
1201 pg->bypassed = 0;
1202
1203 if (--m->pg_init_in_progress)
1204 /* Activations of other paths are still on going */
1205 goto out;
1206
1207 if (!m->pg_init_required)
1208 m->queue_io = 0;
1209
1210 m->pg_init_delay_retry = delay_retry;
1211 queue_work(kmultipathd, &m->process_queued_ios);
1212
1213 /*
1214 * Wake up any thread waiting to suspend.
1215 */
1216 wake_up(&m->pg_init_wait);
1217
1218out:
1219 spin_unlock_irqrestore(&m->lock, flags);
1220}
1221
1222static void activate_path(struct work_struct *work)
1223{
1224 struct pgpath *pgpath =
1225 container_of(work, struct pgpath, activate_path.work);
1226
1227 scsi_dh_activate(bdev_get_queue(pgpath->path.dev->bdev),
1228 pg_init_done, pgpath);
1229}
1230
1231/*
1232 * end_io handling
1233 */
1234static int do_end_io(struct multipath *m, struct request *clone,
1235 int error, struct dm_mpath_io *mpio)
1236{
1237 /*
1238 * We don't queue any clone request inside the multipath target
1239 * during end I/O handling, since those clone requests don't have
1240 * bio clones. If we queue them inside the multipath target,
1241 * we need to make bio clones, that requires memory allocation.
1242 * (See drivers/md/dm.c:end_clone_bio() about why the clone requests
1243 * don't have bio clones.)
1244 * Instead of queueing the clone request here, we queue the original
1245 * request into dm core, which will remake a clone request and
1246 * clone bios for it and resubmit it later.
1247 */
1248 int r = DM_ENDIO_REQUEUE;
1249 unsigned long flags;
1250
1251 if (!error && !clone->errors)
1252 return 0; /* I/O complete */
1253
1254 if (error == -EOPNOTSUPP || error == -EREMOTEIO || error == -EILSEQ)
1255 return error;
1256
1257 if (mpio->pgpath)
1258 fail_path(mpio->pgpath);
1259
1260 spin_lock_irqsave(&m->lock, flags);
1261 if (!m->nr_valid_paths) {
1262 if (!m->queue_if_no_path) {
1263 if (!__must_push_back(m))
1264 r = -EIO;
1265 } else {
1266 if (error == -EBADE)
1267 r = error;
1268 }
1269 }
1270 spin_unlock_irqrestore(&m->lock, flags);
1271
1272 return r;
1273}
1274
1275static int multipath_end_io(struct dm_target *ti, struct request *clone,
1276 int error, union map_info *map_context)
1277{
1278 struct multipath *m = ti->private;
1279 struct dm_mpath_io *mpio = map_context->ptr;
1280 struct pgpath *pgpath = mpio->pgpath;
1281 struct path_selector *ps;
1282 int r;
1283
1284 BUG_ON(!mpio);
1285
1286 r = do_end_io(m, clone, error, mpio);
1287 if (pgpath) {
1288 ps = &pgpath->pg->ps;
1289 if (ps->type->end_io)
1290 ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
1291 }
1292 clear_mapinfo(m, map_context);
1293
1294 return r;
1295}
1296
1297/*
1298 * Suspend can't complete until all the I/O is processed so if
1299 * the last path fails we must error any remaining I/O.
1300 * Note that if the freeze_bdev fails while suspending, the
1301 * queue_if_no_path state is lost - userspace should reset it.
1302 */
1303static void multipath_presuspend(struct dm_target *ti)
1304{
1305 struct multipath *m = (struct multipath *) ti->private;
1306
1307 queue_if_no_path(m, 0, 1);
1308}
1309
1310static void multipath_postsuspend(struct dm_target *ti)
1311{
1312 struct multipath *m = ti->private;
1313
1314 mutex_lock(&m->work_mutex);
1315 flush_multipath_work(m);
1316 mutex_unlock(&m->work_mutex);
1317}
1318
1319/*
1320 * Restore the queue_if_no_path setting.
1321 */
1322static void multipath_resume(struct dm_target *ti)
1323{
1324 struct multipath *m = (struct multipath *) ti->private;
1325 unsigned long flags;
1326
1327 spin_lock_irqsave(&m->lock, flags);
1328 m->queue_if_no_path = m->saved_queue_if_no_path;
1329 spin_unlock_irqrestore(&m->lock, flags);
1330}
1331
1332/*
1333 * Info output has the following format:
1334 * num_multipath_feature_args [multipath_feature_args]*
1335 * num_handler_status_args [handler_status_args]*
1336 * num_groups init_group_number
1337 * [A|D|E num_ps_status_args [ps_status_args]*
1338 * num_paths num_selector_args
1339 * [path_dev A|F fail_count [selector_args]* ]+ ]+
1340 *
1341 * Table output has the following format (identical to the constructor string):
1342 * num_feature_args [features_args]*
1343 * num_handler_args hw_handler [hw_handler_args]*
1344 * num_groups init_group_number
1345 * [priority selector-name num_ps_args [ps_args]*
1346 * num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
1347 */
1348static int multipath_status(struct dm_target *ti, status_type_t type,
1349 char *result, unsigned int maxlen)
1350{
1351 int sz = 0;
1352 unsigned long flags;
1353 struct multipath *m = (struct multipath *) ti->private;
1354 struct priority_group *pg;
1355 struct pgpath *p;
1356 unsigned pg_num;
1357 char state;
1358
1359 spin_lock_irqsave(&m->lock, flags);
1360
1361 /* Features */
1362 if (type == STATUSTYPE_INFO)
1363 DMEMIT("2 %u %u ", m->queue_size, m->pg_init_count);
1364 else {
1365 DMEMIT("%u ", m->queue_if_no_path +
1366 (m->pg_init_retries > 0) * 2 +
1367 (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT) * 2);
1368 if (m->queue_if_no_path)
1369 DMEMIT("queue_if_no_path ");
1370 if (m->pg_init_retries)
1371 DMEMIT("pg_init_retries %u ", m->pg_init_retries);
1372 if (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT)
1373 DMEMIT("pg_init_delay_msecs %u ", m->pg_init_delay_msecs);
1374 }
1375
1376 if (!m->hw_handler_name || type == STATUSTYPE_INFO)
1377 DMEMIT("0 ");
1378 else
1379 DMEMIT("1 %s ", m->hw_handler_name);
1380
1381 DMEMIT("%u ", m->nr_priority_groups);
1382
1383 if (m->next_pg)
1384 pg_num = m->next_pg->pg_num;
1385 else if (m->current_pg)
1386 pg_num = m->current_pg->pg_num;
1387 else
1388 pg_num = (m->nr_priority_groups ? 1 : 0);
1389
1390 DMEMIT("%u ", pg_num);
1391
1392 switch (type) {
1393 case STATUSTYPE_INFO:
1394 list_for_each_entry(pg, &m->priority_groups, list) {
1395 if (pg->bypassed)
1396 state = 'D'; /* Disabled */
1397 else if (pg == m->current_pg)
1398 state = 'A'; /* Currently Active */
1399 else
1400 state = 'E'; /* Enabled */
1401
1402 DMEMIT("%c ", state);
1403
1404 if (pg->ps.type->status)
1405 sz += pg->ps.type->status(&pg->ps, NULL, type,
1406 result + sz,
1407 maxlen - sz);
1408 else
1409 DMEMIT("0 ");
1410
1411 DMEMIT("%u %u ", pg->nr_pgpaths,
1412 pg->ps.type->info_args);
1413
1414 list_for_each_entry(p, &pg->pgpaths, list) {
1415 DMEMIT("%s %s %u ", p->path.dev->name,
1416 p->is_active ? "A" : "F",
1417 p->fail_count);
1418 if (pg->ps.type->status)
1419 sz += pg->ps.type->status(&pg->ps,
1420 &p->path, type, result + sz,
1421 maxlen - sz);
1422 }
1423 }
1424 break;
1425
1426 case STATUSTYPE_TABLE:
1427 list_for_each_entry(pg, &m->priority_groups, list) {
1428 DMEMIT("%s ", pg->ps.type->name);
1429
1430 if (pg->ps.type->status)
1431 sz += pg->ps.type->status(&pg->ps, NULL, type,
1432 result + sz,
1433 maxlen - sz);
1434 else
1435 DMEMIT("0 ");
1436
1437 DMEMIT("%u %u ", pg->nr_pgpaths,
1438 pg->ps.type->table_args);
1439
1440 list_for_each_entry(p, &pg->pgpaths, list) {
1441 DMEMIT("%s ", p->path.dev->name);
1442 if (pg->ps.type->status)
1443 sz += pg->ps.type->status(&pg->ps,
1444 &p->path, type, result + sz,
1445 maxlen - sz);
1446 }
1447 }
1448 break;
1449 }
1450
1451 spin_unlock_irqrestore(&m->lock, flags);
1452
1453 return 0;
1454}
1455
1456static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
1457{
1458 int r = -EINVAL;
1459 struct dm_dev *dev;
1460 struct multipath *m = (struct multipath *) ti->private;
1461 action_fn action;
1462
1463 mutex_lock(&m->work_mutex);
1464
1465 if (dm_suspended(ti)) {
1466 r = -EBUSY;
1467 goto out;
1468 }
1469
1470 if (argc == 1) {
1471 if (!strcasecmp(argv[0], "queue_if_no_path")) {
1472 r = queue_if_no_path(m, 1, 0);
1473 goto out;
1474 } else if (!strcasecmp(argv[0], "fail_if_no_path")) {
1475 r = queue_if_no_path(m, 0, 0);
1476 goto out;
1477 }
1478 }
1479
1480 if (argc != 2) {
1481 DMWARN("Unrecognised multipath message received.");
1482 goto out;
1483 }
1484
1485 if (!strcasecmp(argv[0], "disable_group")) {
1486 r = bypass_pg_num(m, argv[1], 1);
1487 goto out;
1488 } else if (!strcasecmp(argv[0], "enable_group")) {
1489 r = bypass_pg_num(m, argv[1], 0);
1490 goto out;
1491 } else if (!strcasecmp(argv[0], "switch_group")) {
1492 r = switch_pg_num(m, argv[1]);
1493 goto out;
1494 } else if (!strcasecmp(argv[0], "reinstate_path"))
1495 action = reinstate_path;
1496 else if (!strcasecmp(argv[0], "fail_path"))
1497 action = fail_path;
1498 else {
1499 DMWARN("Unrecognised multipath message received.");
1500 goto out;
1501 }
1502
1503 r = dm_get_device(ti, argv[1], dm_table_get_mode(ti->table), &dev);
1504 if (r) {
1505 DMWARN("message: error getting device %s",
1506 argv[1]);
1507 goto out;
1508 }
1509
1510 r = action_dev(m, dev, action);
1511
1512 dm_put_device(ti, dev);
1513
1514out:
1515 mutex_unlock(&m->work_mutex);
1516 return r;
1517}
1518
1519static int multipath_ioctl(struct dm_target *ti, unsigned int cmd,
1520 unsigned long arg)
1521{
1522 struct multipath *m = ti->private;
1523 struct pgpath *pgpath;
1524 struct block_device *bdev;
1525 fmode_t mode;
1526 unsigned long flags;
1527 int r;
1528
1529again:
1530 bdev = NULL;
1531 mode = 0;
1532 r = 0;
1533
1534 spin_lock_irqsave(&m->lock, flags);
1535
1536 if (!m->current_pgpath)
1537 __choose_pgpath(m, 0);
1538
1539 pgpath = m->current_pgpath;
1540
1541 if (pgpath) {
1542 bdev = pgpath->path.dev->bdev;
1543 mode = pgpath->path.dev->mode;
1544 }
1545
1546 if ((pgpath && m->queue_io) || (!pgpath && m->queue_if_no_path))
1547 r = -EAGAIN;
1548 else if (!bdev)
1549 r = -EIO;
1550
1551 spin_unlock_irqrestore(&m->lock, flags);
1552
1553 /*
1554 * Only pass ioctls through if the device sizes match exactly.
1555 */
1556 if (!r && ti->len != i_size_read(bdev->bd_inode) >> SECTOR_SHIFT)
1557 r = scsi_verify_blk_ioctl(NULL, cmd);
1558
1559 if (r == -EAGAIN && !fatal_signal_pending(current)) {
1560 queue_work(kmultipathd, &m->process_queued_ios);
1561 msleep(10);
1562 goto again;
1563 }
1564
1565 return r ? : __blkdev_driver_ioctl(bdev, mode, cmd, arg);
1566}
1567
1568static int multipath_iterate_devices(struct dm_target *ti,
1569 iterate_devices_callout_fn fn, void *data)
1570{
1571 struct multipath *m = ti->private;
1572 struct priority_group *pg;
1573 struct pgpath *p;
1574 int ret = 0;
1575
1576 list_for_each_entry(pg, &m->priority_groups, list) {
1577 list_for_each_entry(p, &pg->pgpaths, list) {
1578 ret = fn(ti, p->path.dev, ti->begin, ti->len, data);
1579 if (ret)
1580 goto out;
1581 }
1582 }
1583
1584out:
1585 return ret;
1586}
1587
1588static int __pgpath_busy(struct pgpath *pgpath)
1589{
1590 struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
1591
1592 return dm_underlying_device_busy(q);
1593}
1594
1595/*
1596 * We return "busy", only when we can map I/Os but underlying devices
1597 * are busy (so even if we map I/Os now, the I/Os will wait on
1598 * the underlying queue).
1599 * In other words, if we want to kill I/Os or queue them inside us
1600 * due to map unavailability, we don't return "busy". Otherwise,
1601 * dm core won't give us the I/Os and we can't do what we want.
1602 */
1603static int multipath_busy(struct dm_target *ti)
1604{
1605 int busy = 0, has_active = 0;
1606 struct multipath *m = ti->private;
1607 struct priority_group *pg;
1608 struct pgpath *pgpath;
1609 unsigned long flags;
1610
1611 spin_lock_irqsave(&m->lock, flags);
1612
1613 /* Guess which priority_group will be used at next mapping time */
1614 if (unlikely(!m->current_pgpath && m->next_pg))
1615 pg = m->next_pg;
1616 else if (likely(m->current_pg))
1617 pg = m->current_pg;
1618 else
1619 /*
1620 * We don't know which pg will be used at next mapping time.
1621 * We don't call __choose_pgpath() here to avoid to trigger
1622 * pg_init just by busy checking.
1623 * So we don't know whether underlying devices we will be using
1624 * at next mapping time are busy or not. Just try mapping.
1625 */
1626 goto out;
1627
1628 /*
1629 * If there is one non-busy active path at least, the path selector
1630 * will be able to select it. So we consider such a pg as not busy.
1631 */
1632 busy = 1;
1633 list_for_each_entry(pgpath, &pg->pgpaths, list)
1634 if (pgpath->is_active) {
1635 has_active = 1;
1636
1637 if (!__pgpath_busy(pgpath)) {
1638 busy = 0;
1639 break;
1640 }
1641 }
1642
1643 if (!has_active)
1644 /*
1645 * No active path in this pg, so this pg won't be used and
1646 * the current_pg will be changed at next mapping time.
1647 * We need to try mapping to determine it.
1648 */
1649 busy = 0;
1650
1651out:
1652 spin_unlock_irqrestore(&m->lock, flags);
1653
1654 return busy;
1655}
1656
1657/*-----------------------------------------------------------------
1658 * Module setup
1659 *---------------------------------------------------------------*/
1660static struct target_type multipath_target = {
1661 .name = "multipath",
1662 .version = {1, 4, 0},
1663 .module = THIS_MODULE,
1664 .ctr = multipath_ctr,
1665 .dtr = multipath_dtr,
1666 .map_rq = multipath_map,
1667 .rq_end_io = multipath_end_io,
1668 .presuspend = multipath_presuspend,
1669 .postsuspend = multipath_postsuspend,
1670 .resume = multipath_resume,
1671 .status = multipath_status,
1672 .message = multipath_message,
1673 .ioctl = multipath_ioctl,
1674 .iterate_devices = multipath_iterate_devices,
1675 .busy = multipath_busy,
1676};
1677
1678static int __init dm_multipath_init(void)
1679{
1680 int r;
1681
1682 /* allocate a slab for the dm_ios */
1683 _mpio_cache = KMEM_CACHE(dm_mpath_io, 0);
1684 if (!_mpio_cache)
1685 return -ENOMEM;
1686
1687 r = dm_register_target(&multipath_target);
1688 if (r < 0) {
1689 DMERR("register failed %d", r);
1690 kmem_cache_destroy(_mpio_cache);
1691 return -EINVAL;
1692 }
1693
1694 kmultipathd = alloc_workqueue("kmpathd", WQ_MEM_RECLAIM, 0);
1695 if (!kmultipathd) {
1696 DMERR("failed to create workqueue kmpathd");
1697 dm_unregister_target(&multipath_target);
1698 kmem_cache_destroy(_mpio_cache);
1699 return -ENOMEM;
1700 }
1701
1702 /*
1703 * A separate workqueue is used to handle the device handlers
1704 * to avoid overloading existing workqueue. Overloading the
1705 * old workqueue would also create a bottleneck in the
1706 * path of the storage hardware device activation.
1707 */
1708 kmpath_handlerd = alloc_ordered_workqueue("kmpath_handlerd",
1709 WQ_MEM_RECLAIM);
1710 if (!kmpath_handlerd) {
1711 DMERR("failed to create workqueue kmpath_handlerd");
1712 destroy_workqueue(kmultipathd);
1713 dm_unregister_target(&multipath_target);
1714 kmem_cache_destroy(_mpio_cache);
1715 return -ENOMEM;
1716 }
1717
1718 DMINFO("version %u.%u.%u loaded",
1719 multipath_target.version[0], multipath_target.version[1],
1720 multipath_target.version[2]);
1721
1722 return r;
1723}
1724
1725static void __exit dm_multipath_exit(void)
1726{
1727 destroy_workqueue(kmpath_handlerd);
1728 destroy_workqueue(kmultipathd);
1729
1730 dm_unregister_target(&multipath_target);
1731 kmem_cache_destroy(_mpio_cache);
1732}
1733
1734module_init(dm_multipath_init);
1735module_exit(dm_multipath_exit);
1736
1737MODULE_DESCRIPTION(DM_NAME " multipath target");
1738MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
1739MODULE_LICENSE("GPL");
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");