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Merge git://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211-next
[deliverable/linux.git] / drivers / md / dm-mpath.c
1 /*
2 * Copyright (C) 2003 Sistina Software Limited.
3 * Copyright (C) 2004-2005 Red Hat, Inc. All rights reserved.
4 *
5 * This file is released under the GPL.
6 */
7
8 #include <linux/device-mapper.h>
9
10 #include "dm.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 */
31 struct 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 */
48 struct 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 */
62 struct 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 */
110 struct dm_mpath_io {
111 struct pgpath *pgpath;
112 size_t nr_bytes;
113 };
114
115 typedef int (*action_fn) (struct pgpath *pgpath);
116
117 static struct kmem_cache *_mpio_cache;
118
119 static struct workqueue_struct *kmultipathd, *kmpath_handlerd;
120 static void trigger_event(struct work_struct *work);
121 static void activate_path(struct work_struct *work);
122 static int __pgpath_busy(struct pgpath *pgpath);
123
124
125 /*-----------------------------------------------
126 * Allocation routines
127 *-----------------------------------------------*/
128
129 static 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
141 static void free_pgpath(struct pgpath *pgpath)
142 {
143 kfree(pgpath);
144 }
145
146 static 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
158 static 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
172 static 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
186 static 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
212 static 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
227 static 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
241 static 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
253 static 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
282 static 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
298 static 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
315 static 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
353 failed:
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 */
369 static 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 */
381 static 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
427 out_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 */
436 static 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 if (!m->queue_if_no_path)
449 dm_table_run_md_queue_async(m->ti->table);
450
451 spin_unlock_irqrestore(&m->lock, flags);
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 */
460 static 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 *---------------------------------------------------------------*/
478 static 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
514 static 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
608 static 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
681 static 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;
724 fail:
725 kfree(m->hw_handler_name);
726 m->hw_handler_name = NULL;
727 return ret;
728 }
729
730 static 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
785 static 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
867 static 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
891 static 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
909 static 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 */
920 static 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
946 out:
947 spin_unlock_irqrestore(&m->lock, flags);
948
949 return 0;
950 }
951
952 /*
953 * Reinstate a previously-failed path
954 */
955 static int reinstate_path(struct pgpath *pgpath)
956 {
957 int r = 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 dm_table_run_md_queue_async(m->ti->table);
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
992 out:
993 spin_unlock_irqrestore(&m->lock, flags);
994
995 return r;
996 }
997
998 /*
999 * Fail or reinstate all paths that match the provided struct dm_dev.
1000 */
1001 static int action_dev(struct multipath *m, struct dm_dev *dev,
1002 action_fn action)
1003 {
1004 int r = -EINVAL;
1005 struct pgpath *pgpath;
1006 struct priority_group *pg;
1007
1008 list_for_each_entry(pg, &m->priority_groups, list) {
1009 list_for_each_entry(pgpath, &pg->pgpaths, list) {
1010 if (pgpath->path.dev == dev)
1011 r = action(pgpath);
1012 }
1013 }
1014
1015 return r;
1016 }
1017
1018 /*
1019 * Temporarily try to avoid having to use the specified PG
1020 */
1021 static void bypass_pg(struct multipath *m, struct priority_group *pg,
1022 int bypassed)
1023 {
1024 unsigned long flags;
1025
1026 spin_lock_irqsave(&m->lock, flags);
1027
1028 pg->bypassed = bypassed;
1029 m->current_pgpath = NULL;
1030 m->current_pg = NULL;
1031
1032 spin_unlock_irqrestore(&m->lock, flags);
1033
1034 schedule_work(&m->trigger_event);
1035 }
1036
1037 /*
1038 * Switch to using the specified PG from the next I/O that gets mapped
1039 */
1040 static int switch_pg_num(struct multipath *m, const char *pgstr)
1041 {
1042 struct priority_group *pg;
1043 unsigned pgnum;
1044 unsigned long flags;
1045 char dummy;
1046
1047 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1048 (pgnum > m->nr_priority_groups)) {
1049 DMWARN("invalid PG number supplied to switch_pg_num");
1050 return -EINVAL;
1051 }
1052
1053 spin_lock_irqsave(&m->lock, flags);
1054 list_for_each_entry(pg, &m->priority_groups, list) {
1055 pg->bypassed = 0;
1056 if (--pgnum)
1057 continue;
1058
1059 m->current_pgpath = NULL;
1060 m->current_pg = NULL;
1061 m->next_pg = pg;
1062 }
1063 spin_unlock_irqrestore(&m->lock, flags);
1064
1065 schedule_work(&m->trigger_event);
1066 return 0;
1067 }
1068
1069 /*
1070 * Set/clear bypassed status of a PG.
1071 * PGs are numbered upwards from 1 in the order they were declared.
1072 */
1073 static int bypass_pg_num(struct multipath *m, const char *pgstr, int bypassed)
1074 {
1075 struct priority_group *pg;
1076 unsigned pgnum;
1077 char dummy;
1078
1079 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1080 (pgnum > m->nr_priority_groups)) {
1081 DMWARN("invalid PG number supplied to bypass_pg");
1082 return -EINVAL;
1083 }
1084
1085 list_for_each_entry(pg, &m->priority_groups, list) {
1086 if (!--pgnum)
1087 break;
1088 }
1089
1090 bypass_pg(m, pg, bypassed);
1091 return 0;
1092 }
1093
1094 /*
1095 * Should we retry pg_init immediately?
1096 */
1097 static int pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath)
1098 {
1099 unsigned long flags;
1100 int limit_reached = 0;
1101
1102 spin_lock_irqsave(&m->lock, flags);
1103
1104 if (m->pg_init_count <= m->pg_init_retries && !m->pg_init_disabled)
1105 m->pg_init_required = 1;
1106 else
1107 limit_reached = 1;
1108
1109 spin_unlock_irqrestore(&m->lock, flags);
1110
1111 return limit_reached;
1112 }
1113
1114 static void pg_init_done(void *data, int errors)
1115 {
1116 struct pgpath *pgpath = data;
1117 struct priority_group *pg = pgpath->pg;
1118 struct multipath *m = pg->m;
1119 unsigned long flags;
1120 unsigned delay_retry = 0;
1121
1122 /* device or driver problems */
1123 switch (errors) {
1124 case SCSI_DH_OK:
1125 break;
1126 case SCSI_DH_NOSYS:
1127 if (!m->hw_handler_name) {
1128 errors = 0;
1129 break;
1130 }
1131 DMERR("Could not failover the device: Handler scsi_dh_%s "
1132 "Error %d.", m->hw_handler_name, errors);
1133 /*
1134 * Fail path for now, so we do not ping pong
1135 */
1136 fail_path(pgpath);
1137 break;
1138 case SCSI_DH_DEV_TEMP_BUSY:
1139 /*
1140 * Probably doing something like FW upgrade on the
1141 * controller so try the other pg.
1142 */
1143 bypass_pg(m, pg, 1);
1144 break;
1145 case SCSI_DH_RETRY:
1146 /* Wait before retrying. */
1147 delay_retry = 1;
1148 case SCSI_DH_IMM_RETRY:
1149 case SCSI_DH_RES_TEMP_UNAVAIL:
1150 if (pg_init_limit_reached(m, pgpath))
1151 fail_path(pgpath);
1152 errors = 0;
1153 break;
1154 default:
1155 /*
1156 * We probably do not want to fail the path for a device
1157 * error, but this is what the old dm did. In future
1158 * patches we can do more advanced handling.
1159 */
1160 fail_path(pgpath);
1161 }
1162
1163 spin_lock_irqsave(&m->lock, flags);
1164 if (errors) {
1165 if (pgpath == m->current_pgpath) {
1166 DMERR("Could not failover device. Error %d.", errors);
1167 m->current_pgpath = NULL;
1168 m->current_pg = NULL;
1169 }
1170 } else if (!m->pg_init_required)
1171 pg->bypassed = 0;
1172
1173 if (--m->pg_init_in_progress)
1174 /* Activations of other paths are still on going */
1175 goto out;
1176
1177 if (m->pg_init_required) {
1178 m->pg_init_delay_retry = delay_retry;
1179 if (__pg_init_all_paths(m))
1180 goto out;
1181 }
1182 m->queue_io = 0;
1183
1184 /*
1185 * Wake up any thread waiting to suspend.
1186 */
1187 wake_up(&m->pg_init_wait);
1188
1189 out:
1190 spin_unlock_irqrestore(&m->lock, flags);
1191 }
1192
1193 static void activate_path(struct work_struct *work)
1194 {
1195 struct pgpath *pgpath =
1196 container_of(work, struct pgpath, activate_path.work);
1197
1198 if (pgpath->is_active)
1199 scsi_dh_activate(bdev_get_queue(pgpath->path.dev->bdev),
1200 pg_init_done, pgpath);
1201 else
1202 pg_init_done(pgpath, SCSI_DH_DEV_OFFLINED);
1203 }
1204
1205 static int noretry_error(int error)
1206 {
1207 switch (error) {
1208 case -EOPNOTSUPP:
1209 case -EREMOTEIO:
1210 case -EILSEQ:
1211 case -ENODATA:
1212 case -ENOSPC:
1213 return 1;
1214 }
1215
1216 /* Anything else could be a path failure, so should be retried */
1217 return 0;
1218 }
1219
1220 /*
1221 * end_io handling
1222 */
1223 static int do_end_io(struct multipath *m, struct request *clone,
1224 int error, struct dm_mpath_io *mpio)
1225 {
1226 /*
1227 * We don't queue any clone request inside the multipath target
1228 * during end I/O handling, since those clone requests don't have
1229 * bio clones. If we queue them inside the multipath target,
1230 * we need to make bio clones, that requires memory allocation.
1231 * (See drivers/md/dm.c:end_clone_bio() about why the clone requests
1232 * don't have bio clones.)
1233 * Instead of queueing the clone request here, we queue the original
1234 * request into dm core, which will remake a clone request and
1235 * clone bios for it and resubmit it later.
1236 */
1237 int r = DM_ENDIO_REQUEUE;
1238 unsigned long flags;
1239
1240 if (!error && !clone->errors)
1241 return 0; /* I/O complete */
1242
1243 if (noretry_error(error)) {
1244 if ((clone->cmd_flags & REQ_WRITE_SAME) &&
1245 !clone->q->limits.max_write_same_sectors) {
1246 struct queue_limits *limits;
1247
1248 /* device doesn't really support WRITE SAME, disable it */
1249 limits = dm_get_queue_limits(dm_table_get_md(m->ti->table));
1250 limits->max_write_same_sectors = 0;
1251 }
1252 return error;
1253 }
1254
1255 if (mpio->pgpath)
1256 fail_path(mpio->pgpath);
1257
1258 spin_lock_irqsave(&m->lock, flags);
1259 if (!m->nr_valid_paths) {
1260 if (!m->queue_if_no_path) {
1261 if (!__must_push_back(m))
1262 r = -EIO;
1263 } else {
1264 if (error == -EBADE)
1265 r = error;
1266 }
1267 }
1268 spin_unlock_irqrestore(&m->lock, flags);
1269
1270 return r;
1271 }
1272
1273 static int multipath_end_io(struct dm_target *ti, struct request *clone,
1274 int error, union map_info *map_context)
1275 {
1276 struct multipath *m = ti->private;
1277 struct dm_mpath_io *mpio = map_context->ptr;
1278 struct pgpath *pgpath;
1279 struct path_selector *ps;
1280 int r;
1281
1282 BUG_ON(!mpio);
1283
1284 r = do_end_io(m, clone, error, mpio);
1285 pgpath = mpio->pgpath;
1286 if (pgpath) {
1287 ps = &pgpath->pg->ps;
1288 if (ps->type->end_io)
1289 ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
1290 }
1291 clear_mapinfo(m, map_context);
1292
1293 return r;
1294 }
1295
1296 /*
1297 * Suspend can't complete until all the I/O is processed so if
1298 * the last path fails we must error any remaining I/O.
1299 * Note that if the freeze_bdev fails while suspending, the
1300 * queue_if_no_path state is lost - userspace should reset it.
1301 */
1302 static void multipath_presuspend(struct dm_target *ti)
1303 {
1304 struct multipath *m = (struct multipath *) ti->private;
1305
1306 queue_if_no_path(m, 0, 1);
1307 }
1308
1309 static void multipath_postsuspend(struct dm_target *ti)
1310 {
1311 struct multipath *m = ti->private;
1312
1313 mutex_lock(&m->work_mutex);
1314 flush_multipath_work(m);
1315 mutex_unlock(&m->work_mutex);
1316 }
1317
1318 /*
1319 * Restore the queue_if_no_path setting.
1320 */
1321 static void multipath_resume(struct dm_target *ti)
1322 {
1323 struct multipath *m = (struct multipath *) ti->private;
1324 unsigned long flags;
1325
1326 spin_lock_irqsave(&m->lock, flags);
1327 m->queue_if_no_path = m->saved_queue_if_no_path;
1328 spin_unlock_irqrestore(&m->lock, flags);
1329 }
1330
1331 /*
1332 * Info output has the following format:
1333 * num_multipath_feature_args [multipath_feature_args]*
1334 * num_handler_status_args [handler_status_args]*
1335 * num_groups init_group_number
1336 * [A|D|E num_ps_status_args [ps_status_args]*
1337 * num_paths num_selector_args
1338 * [path_dev A|F fail_count [selector_args]* ]+ ]+
1339 *
1340 * Table output has the following format (identical to the constructor string):
1341 * num_feature_args [features_args]*
1342 * num_handler_args hw_handler [hw_handler_args]*
1343 * num_groups init_group_number
1344 * [priority selector-name num_ps_args [ps_args]*
1345 * num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
1346 */
1347 static void multipath_status(struct dm_target *ti, status_type_t type,
1348 unsigned status_flags, char *result, unsigned maxlen)
1349 {
1350 int sz = 0;
1351 unsigned long flags;
1352 struct multipath *m = (struct multipath *) ti->private;
1353 struct priority_group *pg;
1354 struct pgpath *p;
1355 unsigned pg_num;
1356 char state;
1357
1358 spin_lock_irqsave(&m->lock, flags);
1359
1360 /* Features */
1361 if (type == STATUSTYPE_INFO)
1362 DMEMIT("2 %u %u ", m->queue_io, m->pg_init_count);
1363 else {
1364 DMEMIT("%u ", m->queue_if_no_path +
1365 (m->pg_init_retries > 0) * 2 +
1366 (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT) * 2 +
1367 m->retain_attached_hw_handler);
1368 if (m->queue_if_no_path)
1369 DMEMIT("queue_if_no_path ");
1370 if (m->pg_init_retries)
1371 DMEMIT("pg_init_retries %u ", m->pg_init_retries);
1372 if (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT)
1373 DMEMIT("pg_init_delay_msecs %u ", m->pg_init_delay_msecs);
1374 if (m->retain_attached_hw_handler)
1375 DMEMIT("retain_attached_hw_handler ");
1376 }
1377
1378 if (!m->hw_handler_name || type == STATUSTYPE_INFO)
1379 DMEMIT("0 ");
1380 else
1381 DMEMIT("1 %s ", m->hw_handler_name);
1382
1383 DMEMIT("%u ", m->nr_priority_groups);
1384
1385 if (m->next_pg)
1386 pg_num = m->next_pg->pg_num;
1387 else if (m->current_pg)
1388 pg_num = m->current_pg->pg_num;
1389 else
1390 pg_num = (m->nr_priority_groups ? 1 : 0);
1391
1392 DMEMIT("%u ", pg_num);
1393
1394 switch (type) {
1395 case STATUSTYPE_INFO:
1396 list_for_each_entry(pg, &m->priority_groups, list) {
1397 if (pg->bypassed)
1398 state = 'D'; /* Disabled */
1399 else if (pg == m->current_pg)
1400 state = 'A'; /* Currently Active */
1401 else
1402 state = 'E'; /* Enabled */
1403
1404 DMEMIT("%c ", state);
1405
1406 if (pg->ps.type->status)
1407 sz += pg->ps.type->status(&pg->ps, NULL, type,
1408 result + sz,
1409 maxlen - sz);
1410 else
1411 DMEMIT("0 ");
1412
1413 DMEMIT("%u %u ", pg->nr_pgpaths,
1414 pg->ps.type->info_args);
1415
1416 list_for_each_entry(p, &pg->pgpaths, list) {
1417 DMEMIT("%s %s %u ", p->path.dev->name,
1418 p->is_active ? "A" : "F",
1419 p->fail_count);
1420 if (pg->ps.type->status)
1421 sz += pg->ps.type->status(&pg->ps,
1422 &p->path, type, result + sz,
1423 maxlen - sz);
1424 }
1425 }
1426 break;
1427
1428 case STATUSTYPE_TABLE:
1429 list_for_each_entry(pg, &m->priority_groups, list) {
1430 DMEMIT("%s ", pg->ps.type->name);
1431
1432 if (pg->ps.type->status)
1433 sz += pg->ps.type->status(&pg->ps, NULL, type,
1434 result + sz,
1435 maxlen - sz);
1436 else
1437 DMEMIT("0 ");
1438
1439 DMEMIT("%u %u ", pg->nr_pgpaths,
1440 pg->ps.type->table_args);
1441
1442 list_for_each_entry(p, &pg->pgpaths, list) {
1443 DMEMIT("%s ", p->path.dev->name);
1444 if (pg->ps.type->status)
1445 sz += pg->ps.type->status(&pg->ps,
1446 &p->path, type, result + sz,
1447 maxlen - sz);
1448 }
1449 }
1450 break;
1451 }
1452
1453 spin_unlock_irqrestore(&m->lock, flags);
1454 }
1455
1456 static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
1457 {
1458 int r = -EINVAL;
1459 struct dm_dev *dev;
1460 struct multipath *m = (struct multipath *) ti->private;
1461 action_fn action;
1462
1463 mutex_lock(&m->work_mutex);
1464
1465 if (dm_suspended(ti)) {
1466 r = -EBUSY;
1467 goto out;
1468 }
1469
1470 if (argc == 1) {
1471 if (!strcasecmp(argv[0], "queue_if_no_path")) {
1472 r = queue_if_no_path(m, 1, 0);
1473 goto out;
1474 } else if (!strcasecmp(argv[0], "fail_if_no_path")) {
1475 r = queue_if_no_path(m, 0, 0);
1476 goto out;
1477 }
1478 }
1479
1480 if (argc != 2) {
1481 DMWARN("Invalid multipath message arguments. Expected 2 arguments, got %d.", argc);
1482 goto out;
1483 }
1484
1485 if (!strcasecmp(argv[0], "disable_group")) {
1486 r = bypass_pg_num(m, argv[1], 1);
1487 goto out;
1488 } else if (!strcasecmp(argv[0], "enable_group")) {
1489 r = bypass_pg_num(m, argv[1], 0);
1490 goto out;
1491 } else if (!strcasecmp(argv[0], "switch_group")) {
1492 r = switch_pg_num(m, argv[1]);
1493 goto out;
1494 } else if (!strcasecmp(argv[0], "reinstate_path"))
1495 action = reinstate_path;
1496 else if (!strcasecmp(argv[0], "fail_path"))
1497 action = fail_path;
1498 else {
1499 DMWARN("Unrecognised multipath message received: %s", argv[0]);
1500 goto out;
1501 }
1502
1503 r = dm_get_device(ti, argv[1], dm_table_get_mode(ti->table), &dev);
1504 if (r) {
1505 DMWARN("message: error getting device %s",
1506 argv[1]);
1507 goto out;
1508 }
1509
1510 r = action_dev(m, dev, action);
1511
1512 dm_put_device(ti, dev);
1513
1514 out:
1515 mutex_unlock(&m->work_mutex);
1516 return r;
1517 }
1518
1519 static int multipath_ioctl(struct dm_target *ti, unsigned int cmd,
1520 unsigned long arg)
1521 {
1522 struct multipath *m = ti->private;
1523 struct pgpath *pgpath;
1524 struct block_device *bdev;
1525 fmode_t mode;
1526 unsigned long flags;
1527 int r;
1528
1529 bdev = NULL;
1530 mode = 0;
1531 r = 0;
1532
1533 spin_lock_irqsave(&m->lock, flags);
1534
1535 if (!m->current_pgpath)
1536 __choose_pgpath(m, 0);
1537
1538 pgpath = m->current_pgpath;
1539
1540 if (pgpath) {
1541 bdev = pgpath->path.dev->bdev;
1542 mode = pgpath->path.dev->mode;
1543 }
1544
1545 if ((pgpath && m->queue_io) || (!pgpath && m->queue_if_no_path))
1546 r = -ENOTCONN;
1547 else if (!bdev)
1548 r = -EIO;
1549
1550 spin_unlock_irqrestore(&m->lock, flags);
1551
1552 /*
1553 * Only pass ioctls through if the device sizes match exactly.
1554 */
1555 if (!bdev || ti->len != i_size_read(bdev->bd_inode) >> SECTOR_SHIFT) {
1556 int err = scsi_verify_blk_ioctl(NULL, cmd);
1557 if (err)
1558 r = err;
1559 }
1560
1561 if (r == -ENOTCONN && !fatal_signal_pending(current)) {
1562 spin_lock_irqsave(&m->lock, flags);
1563 if (!m->current_pg) {
1564 /* Path status changed, redo selection */
1565 __choose_pgpath(m, 0);
1566 }
1567 if (m->pg_init_required)
1568 __pg_init_all_paths(m);
1569 spin_unlock_irqrestore(&m->lock, flags);
1570 dm_table_run_md_queue_async(m->ti->table);
1571 }
1572
1573 return r ? : __blkdev_driver_ioctl(bdev, mode, cmd, arg);
1574 }
1575
1576 static int multipath_iterate_devices(struct dm_target *ti,
1577 iterate_devices_callout_fn fn, void *data)
1578 {
1579 struct multipath *m = ti->private;
1580 struct priority_group *pg;
1581 struct pgpath *p;
1582 int ret = 0;
1583
1584 list_for_each_entry(pg, &m->priority_groups, list) {
1585 list_for_each_entry(p, &pg->pgpaths, list) {
1586 ret = fn(ti, p->path.dev, ti->begin, ti->len, data);
1587 if (ret)
1588 goto out;
1589 }
1590 }
1591
1592 out:
1593 return ret;
1594 }
1595
1596 static int __pgpath_busy(struct pgpath *pgpath)
1597 {
1598 struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
1599
1600 return dm_underlying_device_busy(q);
1601 }
1602
1603 /*
1604 * We return "busy", only when we can map I/Os but underlying devices
1605 * are busy (so even if we map I/Os now, the I/Os will wait on
1606 * the underlying queue).
1607 * In other words, if we want to kill I/Os or queue them inside us
1608 * due to map unavailability, we don't return "busy". Otherwise,
1609 * dm core won't give us the I/Os and we can't do what we want.
1610 */
1611 static int multipath_busy(struct dm_target *ti)
1612 {
1613 int busy = 0, has_active = 0;
1614 struct multipath *m = ti->private;
1615 struct priority_group *pg;
1616 struct pgpath *pgpath;
1617 unsigned long flags;
1618
1619 spin_lock_irqsave(&m->lock, flags);
1620
1621 /* pg_init in progress, requeue until done */
1622 if (!pg_ready(m)) {
1623 busy = 1;
1624 goto out;
1625 }
1626 /* Guess which priority_group will be used at next mapping time */
1627 if (unlikely(!m->current_pgpath && m->next_pg))
1628 pg = m->next_pg;
1629 else if (likely(m->current_pg))
1630 pg = m->current_pg;
1631 else
1632 /*
1633 * We don't know which pg will be used at next mapping time.
1634 * We don't call __choose_pgpath() here to avoid to trigger
1635 * pg_init just by busy checking.
1636 * So we don't know whether underlying devices we will be using
1637 * at next mapping time are busy or not. Just try mapping.
1638 */
1639 goto out;
1640
1641 /*
1642 * If there is one non-busy active path at least, the path selector
1643 * will be able to select it. So we consider such a pg as not busy.
1644 */
1645 busy = 1;
1646 list_for_each_entry(pgpath, &pg->pgpaths, list)
1647 if (pgpath->is_active) {
1648 has_active = 1;
1649
1650 if (!__pgpath_busy(pgpath)) {
1651 busy = 0;
1652 break;
1653 }
1654 }
1655
1656 if (!has_active)
1657 /*
1658 * No active path in this pg, so this pg won't be used and
1659 * the current_pg will be changed at next mapping time.
1660 * We need to try mapping to determine it.
1661 */
1662 busy = 0;
1663
1664 out:
1665 spin_unlock_irqrestore(&m->lock, flags);
1666
1667 return busy;
1668 }
1669
1670 /*-----------------------------------------------------------------
1671 * Module setup
1672 *---------------------------------------------------------------*/
1673 static struct target_type multipath_target = {
1674 .name = "multipath",
1675 .version = {1, 7, 0},
1676 .module = THIS_MODULE,
1677 .ctr = multipath_ctr,
1678 .dtr = multipath_dtr,
1679 .map_rq = multipath_map,
1680 .rq_end_io = multipath_end_io,
1681 .presuspend = multipath_presuspend,
1682 .postsuspend = multipath_postsuspend,
1683 .resume = multipath_resume,
1684 .status = multipath_status,
1685 .message = multipath_message,
1686 .ioctl = multipath_ioctl,
1687 .iterate_devices = multipath_iterate_devices,
1688 .busy = multipath_busy,
1689 };
1690
1691 static int __init dm_multipath_init(void)
1692 {
1693 int r;
1694
1695 /* allocate a slab for the dm_ios */
1696 _mpio_cache = KMEM_CACHE(dm_mpath_io, 0);
1697 if (!_mpio_cache)
1698 return -ENOMEM;
1699
1700 r = dm_register_target(&multipath_target);
1701 if (r < 0) {
1702 DMERR("register failed %d", r);
1703 kmem_cache_destroy(_mpio_cache);
1704 return -EINVAL;
1705 }
1706
1707 kmultipathd = alloc_workqueue("kmpathd", WQ_MEM_RECLAIM, 0);
1708 if (!kmultipathd) {
1709 DMERR("failed to create workqueue kmpathd");
1710 dm_unregister_target(&multipath_target);
1711 kmem_cache_destroy(_mpio_cache);
1712 return -ENOMEM;
1713 }
1714
1715 /*
1716 * A separate workqueue is used to handle the device handlers
1717 * to avoid overloading existing workqueue. Overloading the
1718 * old workqueue would also create a bottleneck in the
1719 * path of the storage hardware device activation.
1720 */
1721 kmpath_handlerd = alloc_ordered_workqueue("kmpath_handlerd",
1722 WQ_MEM_RECLAIM);
1723 if (!kmpath_handlerd) {
1724 DMERR("failed to create workqueue kmpath_handlerd");
1725 destroy_workqueue(kmultipathd);
1726 dm_unregister_target(&multipath_target);
1727 kmem_cache_destroy(_mpio_cache);
1728 return -ENOMEM;
1729 }
1730
1731 DMINFO("version %u.%u.%u loaded",
1732 multipath_target.version[0], multipath_target.version[1],
1733 multipath_target.version[2]);
1734
1735 return r;
1736 }
1737
1738 static void __exit dm_multipath_exit(void)
1739 {
1740 destroy_workqueue(kmpath_handlerd);
1741 destroy_workqueue(kmultipathd);
1742
1743 dm_unregister_target(&multipath_target);
1744 kmem_cache_destroy(_mpio_cache);
1745 }
1746
1747 module_init(dm_multipath_init);
1748 module_exit(dm_multipath_exit);
1749
1750 MODULE_DESCRIPTION(DM_NAME " multipath target");
1751 MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
1752 MODULE_LICENSE("GPL");
Linux kernel - Deliverables
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