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