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Merge tag 'xtensa-next-20121101' of git://github.com/czankel/xtensa-linux
[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-path-selector.h"
11 #include "dm-uevent.h"
12
13 #include <linux/ctype.h>
14 #include <linux/init.h>
15 #include <linux/mempool.h>
16 #include <linux/module.h>
17 #include <linux/pagemap.h>
18 #include <linux/slab.h>
19 #include <linux/time.h>
20 #include <linux/workqueue.h>
21 #include <linux/delay.h>
22 #include <scsi/scsi_dh.h>
23 #include <linux/atomic.h>
24
25 #define DM_MSG_PREFIX "multipath"
26 #define DM_PG_INIT_DELAY_MSECS 2000
27 #define DM_PG_INIT_DELAY_DEFAULT ((unsigned) -1)
28
29 /* Path properties */
30 struct pgpath {
31 struct list_head list;
32
33 struct priority_group *pg; /* Owning PG */
34 unsigned is_active; /* Path status */
35 unsigned fail_count; /* Cumulative failure count */
36
37 struct dm_path path;
38 struct delayed_work activate_path;
39 };
40
41 #define path_to_pgpath(__pgp) container_of((__pgp), struct pgpath, path)
42
43 /*
44 * Paths are grouped into Priority Groups and numbered from 1 upwards.
45 * Each has a path selector which controls which path gets used.
46 */
47 struct priority_group {
48 struct list_head list;
49
50 struct multipath *m; /* Owning multipath instance */
51 struct path_selector ps;
52
53 unsigned pg_num; /* Reference number */
54 unsigned bypassed; /* Temporarily bypass this PG? */
55
56 unsigned nr_pgpaths; /* Number of paths in PG */
57 struct list_head pgpaths;
58 };
59
60 /* Multipath context */
61 struct multipath {
62 struct list_head list;
63 struct dm_target *ti;
64
65 const char *hw_handler_name;
66 char *hw_handler_params;
67
68 spinlock_t lock;
69
70 unsigned nr_priority_groups;
71 struct list_head priority_groups;
72
73 wait_queue_head_t pg_init_wait; /* Wait for pg_init completion */
74
75 unsigned pg_init_required; /* pg_init needs calling? */
76 unsigned pg_init_in_progress; /* Only one pg_init allowed at once */
77 unsigned pg_init_delay_retry; /* Delay pg_init retry? */
78
79 unsigned nr_valid_paths; /* Total number of usable paths */
80 struct pgpath *current_pgpath;
81 struct priority_group *current_pg;
82 struct priority_group *next_pg; /* Switch to this PG if set */
83 unsigned repeat_count; /* I/Os left before calling PS again */
84
85 unsigned queue_io:1; /* Must we queue all I/O? */
86 unsigned queue_if_no_path:1; /* Queue I/O if last path fails? */
87 unsigned saved_queue_if_no_path:1; /* Saved state during suspension */
88 unsigned retain_attached_hw_handler:1; /* If there's already a hw_handler present, don't change it. */
89
90 unsigned pg_init_retries; /* Number of times to retry pg_init */
91 unsigned pg_init_count; /* Number of times pg_init called */
92 unsigned pg_init_delay_msecs; /* Number of msecs before pg_init retry */
93
94 unsigned queue_size;
95 struct work_struct process_queued_ios;
96 struct list_head queued_ios;
97
98 struct work_struct trigger_event;
99
100 /*
101 * We must use a mempool of dm_mpath_io structs so that we
102 * can resubmit bios on error.
103 */
104 mempool_t *mpio_pool;
105
106 struct mutex work_mutex;
107 };
108
109 /*
110 * Context information attached to each bio we process.
111 */
112 struct dm_mpath_io {
113 struct pgpath *pgpath;
114 size_t nr_bytes;
115 };
116
117 typedef int (*action_fn) (struct pgpath *pgpath);
118
119 #define MIN_IOS 256 /* Mempool size */
120
121 static struct kmem_cache *_mpio_cache;
122
123 static struct workqueue_struct *kmultipathd, *kmpath_handlerd;
124 static void process_queued_ios(struct work_struct *work);
125 static void trigger_event(struct work_struct *work);
126 static void activate_path(struct work_struct *work);
127
128
129 /*-----------------------------------------------
130 * Allocation routines
131 *-----------------------------------------------*/
132
133 static struct pgpath *alloc_pgpath(void)
134 {
135 struct pgpath *pgpath = kzalloc(sizeof(*pgpath), GFP_KERNEL);
136
137 if (pgpath) {
138 pgpath->is_active = 1;
139 INIT_DELAYED_WORK(&pgpath->activate_path, activate_path);
140 }
141
142 return pgpath;
143 }
144
145 static void free_pgpath(struct pgpath *pgpath)
146 {
147 kfree(pgpath);
148 }
149
150 static struct priority_group *alloc_priority_group(void)
151 {
152 struct priority_group *pg;
153
154 pg = kzalloc(sizeof(*pg), GFP_KERNEL);
155
156 if (pg)
157 INIT_LIST_HEAD(&pg->pgpaths);
158
159 return pg;
160 }
161
162 static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti)
163 {
164 struct pgpath *pgpath, *tmp;
165 struct multipath *m = ti->private;
166
167 list_for_each_entry_safe(pgpath, tmp, pgpaths, list) {
168 list_del(&pgpath->list);
169 if (m->hw_handler_name)
170 scsi_dh_detach(bdev_get_queue(pgpath->path.dev->bdev));
171 dm_put_device(ti, pgpath->path.dev);
172 free_pgpath(pgpath);
173 }
174 }
175
176 static void free_priority_group(struct priority_group *pg,
177 struct dm_target *ti)
178 {
179 struct path_selector *ps = &pg->ps;
180
181 if (ps->type) {
182 ps->type->destroy(ps);
183 dm_put_path_selector(ps->type);
184 }
185
186 free_pgpaths(&pg->pgpaths, ti);
187 kfree(pg);
188 }
189
190 static struct multipath *alloc_multipath(struct dm_target *ti)
191 {
192 struct multipath *m;
193
194 m = kzalloc(sizeof(*m), GFP_KERNEL);
195 if (m) {
196 INIT_LIST_HEAD(&m->priority_groups);
197 INIT_LIST_HEAD(&m->queued_ios);
198 spin_lock_init(&m->lock);
199 m->queue_io = 1;
200 m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT;
201 INIT_WORK(&m->process_queued_ios, process_queued_ios);
202 INIT_WORK(&m->trigger_event, trigger_event);
203 init_waitqueue_head(&m->pg_init_wait);
204 mutex_init(&m->work_mutex);
205 m->mpio_pool = mempool_create_slab_pool(MIN_IOS, _mpio_cache);
206 if (!m->mpio_pool) {
207 kfree(m);
208 return NULL;
209 }
210 m->ti = ti;
211 ti->private = m;
212 }
213
214 return m;
215 }
216
217 static void free_multipath(struct multipath *m)
218 {
219 struct priority_group *pg, *tmp;
220
221 list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) {
222 list_del(&pg->list);
223 free_priority_group(pg, m->ti);
224 }
225
226 kfree(m->hw_handler_name);
227 kfree(m->hw_handler_params);
228 mempool_destroy(m->mpio_pool);
229 kfree(m);
230 }
231
232 static int set_mapinfo(struct multipath *m, union map_info *info)
233 {
234 struct dm_mpath_io *mpio;
235
236 mpio = mempool_alloc(m->mpio_pool, GFP_ATOMIC);
237 if (!mpio)
238 return -ENOMEM;
239
240 memset(mpio, 0, sizeof(*mpio));
241 info->ptr = mpio;
242
243 return 0;
244 }
245
246 static void clear_mapinfo(struct multipath *m, union map_info *info)
247 {
248 struct dm_mpath_io *mpio = info->ptr;
249
250 info->ptr = NULL;
251 mempool_free(mpio, m->mpio_pool);
252 }
253
254 /*-----------------------------------------------
255 * Path selection
256 *-----------------------------------------------*/
257
258 static void __pg_init_all_paths(struct multipath *m)
259 {
260 struct pgpath *pgpath;
261 unsigned long pg_init_delay = 0;
262
263 m->pg_init_count++;
264 m->pg_init_required = 0;
265 if (m->pg_init_delay_retry)
266 pg_init_delay = msecs_to_jiffies(m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT ?
267 m->pg_init_delay_msecs : DM_PG_INIT_DELAY_MSECS);
268 list_for_each_entry(pgpath, &m->current_pg->pgpaths, list) {
269 /* Skip failed paths */
270 if (!pgpath->is_active)
271 continue;
272 if (queue_delayed_work(kmpath_handlerd, &pgpath->activate_path,
273 pg_init_delay))
274 m->pg_init_in_progress++;
275 }
276 }
277
278 static void __switch_pg(struct multipath *m, struct pgpath *pgpath)
279 {
280 m->current_pg = pgpath->pg;
281
282 /* Must we initialise the PG first, and queue I/O till it's ready? */
283 if (m->hw_handler_name) {
284 m->pg_init_required = 1;
285 m->queue_io = 1;
286 } else {
287 m->pg_init_required = 0;
288 m->queue_io = 0;
289 }
290
291 m->pg_init_count = 0;
292 }
293
294 static int __choose_path_in_pg(struct multipath *m, struct priority_group *pg,
295 size_t nr_bytes)
296 {
297 struct dm_path *path;
298
299 path = pg->ps.type->select_path(&pg->ps, &m->repeat_count, nr_bytes);
300 if (!path)
301 return -ENXIO;
302
303 m->current_pgpath = path_to_pgpath(path);
304
305 if (m->current_pg != pg)
306 __switch_pg(m, m->current_pgpath);
307
308 return 0;
309 }
310
311 static void __choose_pgpath(struct multipath *m, size_t nr_bytes)
312 {
313 struct priority_group *pg;
314 unsigned bypassed = 1;
315
316 if (!m->nr_valid_paths)
317 goto failed;
318
319 /* Were we instructed to switch PG? */
320 if (m->next_pg) {
321 pg = m->next_pg;
322 m->next_pg = NULL;
323 if (!__choose_path_in_pg(m, pg, nr_bytes))
324 return;
325 }
326
327 /* Don't change PG until it has no remaining paths */
328 if (m->current_pg && !__choose_path_in_pg(m, m->current_pg, nr_bytes))
329 return;
330
331 /*
332 * Loop through priority groups until we find a valid path.
333 * First time we skip PGs marked 'bypassed'.
334 * Second time we only try the ones we skipped, but set
335 * pg_init_delay_retry so we do not hammer controllers.
336 */
337 do {
338 list_for_each_entry(pg, &m->priority_groups, list) {
339 if (pg->bypassed == bypassed)
340 continue;
341 if (!__choose_path_in_pg(m, pg, nr_bytes)) {
342 if (!bypassed)
343 m->pg_init_delay_retry = 1;
344 return;
345 }
346 }
347 } while (bypassed--);
348
349 failed:
350 m->current_pgpath = NULL;
351 m->current_pg = NULL;
352 }
353
354 /*
355 * Check whether bios must be queued in the device-mapper core rather
356 * than here in the target.
357 *
358 * m->lock must be held on entry.
359 *
360 * If m->queue_if_no_path and m->saved_queue_if_no_path hold the
361 * same value then we are not between multipath_presuspend()
362 * and multipath_resume() calls and we have no need to check
363 * for the DMF_NOFLUSH_SUSPENDING flag.
364 */
365 static int __must_push_back(struct multipath *m)
366 {
367 return (m->queue_if_no_path != m->saved_queue_if_no_path &&
368 dm_noflush_suspending(m->ti));
369 }
370
371 static int map_io(struct multipath *m, struct request *clone,
372 union map_info *map_context, unsigned was_queued)
373 {
374 int r = DM_MAPIO_REMAPPED;
375 size_t nr_bytes = blk_rq_bytes(clone);
376 unsigned long flags;
377 struct pgpath *pgpath;
378 struct block_device *bdev;
379 struct dm_mpath_io *mpio = map_context->ptr;
380
381 spin_lock_irqsave(&m->lock, flags);
382
383 /* Do we need to select a new pgpath? */
384 if (!m->current_pgpath ||
385 (!m->queue_io && (m->repeat_count && --m->repeat_count == 0)))
386 __choose_pgpath(m, nr_bytes);
387
388 pgpath = m->current_pgpath;
389
390 if (was_queued)
391 m->queue_size--;
392
393 if ((pgpath && m->queue_io) ||
394 (!pgpath && m->queue_if_no_path)) {
395 /* Queue for the daemon to resubmit */
396 list_add_tail(&clone->queuelist, &m->queued_ios);
397 m->queue_size++;
398 if ((m->pg_init_required && !m->pg_init_in_progress) ||
399 !m->queue_io)
400 queue_work(kmultipathd, &m->process_queued_ios);
401 pgpath = NULL;
402 r = DM_MAPIO_SUBMITTED;
403 } else if (pgpath) {
404 bdev = pgpath->path.dev->bdev;
405 clone->q = bdev_get_queue(bdev);
406 clone->rq_disk = bdev->bd_disk;
407 } else if (__must_push_back(m))
408 r = DM_MAPIO_REQUEUE;
409 else
410 r = -EIO; /* Failed */
411
412 mpio->pgpath = pgpath;
413 mpio->nr_bytes = nr_bytes;
414
415 if (r == DM_MAPIO_REMAPPED && pgpath->pg->ps.type->start_io)
416 pgpath->pg->ps.type->start_io(&pgpath->pg->ps, &pgpath->path,
417 nr_bytes);
418
419 spin_unlock_irqrestore(&m->lock, flags);
420
421 return r;
422 }
423
424 /*
425 * If we run out of usable paths, should we queue I/O or error it?
426 */
427 static int queue_if_no_path(struct multipath *m, unsigned queue_if_no_path,
428 unsigned save_old_value)
429 {
430 unsigned long flags;
431
432 spin_lock_irqsave(&m->lock, flags);
433
434 if (save_old_value)
435 m->saved_queue_if_no_path = m->queue_if_no_path;
436 else
437 m->saved_queue_if_no_path = queue_if_no_path;
438 m->queue_if_no_path = queue_if_no_path;
439 if (!m->queue_if_no_path && m->queue_size)
440 queue_work(kmultipathd, &m->process_queued_ios);
441
442 spin_unlock_irqrestore(&m->lock, flags);
443
444 return 0;
445 }
446
447 /*-----------------------------------------------------------------
448 * The multipath daemon is responsible for resubmitting queued ios.
449 *---------------------------------------------------------------*/
450
451 static void dispatch_queued_ios(struct multipath *m)
452 {
453 int r;
454 unsigned long flags;
455 union map_info *info;
456 struct request *clone, *n;
457 LIST_HEAD(cl);
458
459 spin_lock_irqsave(&m->lock, flags);
460 list_splice_init(&m->queued_ios, &cl);
461 spin_unlock_irqrestore(&m->lock, flags);
462
463 list_for_each_entry_safe(clone, n, &cl, queuelist) {
464 list_del_init(&clone->queuelist);
465
466 info = dm_get_rq_mapinfo(clone);
467
468 r = map_io(m, clone, info, 1);
469 if (r < 0) {
470 clear_mapinfo(m, info);
471 dm_kill_unmapped_request(clone, r);
472 } else if (r == DM_MAPIO_REMAPPED)
473 dm_dispatch_request(clone);
474 else if (r == DM_MAPIO_REQUEUE) {
475 clear_mapinfo(m, info);
476 dm_requeue_unmapped_request(clone);
477 }
478 }
479 }
480
481 static void process_queued_ios(struct work_struct *work)
482 {
483 struct multipath *m =
484 container_of(work, struct multipath, process_queued_ios);
485 struct pgpath *pgpath = NULL;
486 unsigned must_queue = 1;
487 unsigned long flags;
488
489 spin_lock_irqsave(&m->lock, flags);
490
491 if (!m->current_pgpath)
492 __choose_pgpath(m, 0);
493
494 pgpath = m->current_pgpath;
495
496 if ((pgpath && !m->queue_io) ||
497 (!pgpath && !m->queue_if_no_path))
498 must_queue = 0;
499
500 if (m->pg_init_required && !m->pg_init_in_progress && pgpath)
501 __pg_init_all_paths(m);
502
503 spin_unlock_irqrestore(&m->lock, flags);
504 if (!must_queue)
505 dispatch_queued_ios(m);
506 }
507
508 /*
509 * An event is triggered whenever a path is taken out of use.
510 * Includes path failure and PG bypass.
511 */
512 static void trigger_event(struct work_struct *work)
513 {
514 struct multipath *m =
515 container_of(work, struct multipath, trigger_event);
516
517 dm_table_event(m->ti->table);
518 }
519
520 /*-----------------------------------------------------------------
521 * Constructor/argument parsing:
522 * <#multipath feature args> [<arg>]*
523 * <#hw_handler args> [hw_handler [<arg>]*]
524 * <#priority groups>
525 * <initial priority group>
526 * [<selector> <#selector args> [<arg>]*
527 * <#paths> <#per-path selector args>
528 * [<path> [<arg>]* ]+ ]+
529 *---------------------------------------------------------------*/
530 static int parse_path_selector(struct dm_arg_set *as, struct priority_group *pg,
531 struct dm_target *ti)
532 {
533 int r;
534 struct path_selector_type *pst;
535 unsigned ps_argc;
536
537 static struct dm_arg _args[] = {
538 {0, 1024, "invalid number of path selector args"},
539 };
540
541 pst = dm_get_path_selector(dm_shift_arg(as));
542 if (!pst) {
543 ti->error = "unknown path selector type";
544 return -EINVAL;
545 }
546
547 r = dm_read_arg_group(_args, as, &ps_argc, &ti->error);
548 if (r) {
549 dm_put_path_selector(pst);
550 return -EINVAL;
551 }
552
553 r = pst->create(&pg->ps, ps_argc, as->argv);
554 if (r) {
555 dm_put_path_selector(pst);
556 ti->error = "path selector constructor failed";
557 return r;
558 }
559
560 pg->ps.type = pst;
561 dm_consume_args(as, ps_argc);
562
563 return 0;
564 }
565
566 static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps,
567 struct dm_target *ti)
568 {
569 int r;
570 struct pgpath *p;
571 struct multipath *m = ti->private;
572 struct request_queue *q = NULL;
573 const char *attached_handler_name;
574
575 /* we need at least a path arg */
576 if (as->argc < 1) {
577 ti->error = "no device given";
578 return ERR_PTR(-EINVAL);
579 }
580
581 p = alloc_pgpath();
582 if (!p)
583 return ERR_PTR(-ENOMEM);
584
585 r = dm_get_device(ti, dm_shift_arg(as), dm_table_get_mode(ti->table),
586 &p->path.dev);
587 if (r) {
588 ti->error = "error getting device";
589 goto bad;
590 }
591
592 if (m->retain_attached_hw_handler || m->hw_handler_name)
593 q = bdev_get_queue(p->path.dev->bdev);
594
595 if (m->retain_attached_hw_handler) {
596 attached_handler_name = scsi_dh_attached_handler_name(q, GFP_KERNEL);
597 if (attached_handler_name) {
598 /*
599 * Reset hw_handler_name to match the attached handler
600 * and clear any hw_handler_params associated with the
601 * ignored handler.
602 *
603 * NB. This modifies the table line to show the actual
604 * handler instead of the original table passed in.
605 */
606 kfree(m->hw_handler_name);
607 m->hw_handler_name = attached_handler_name;
608
609 kfree(m->hw_handler_params);
610 m->hw_handler_params = NULL;
611 }
612 }
613
614 if (m->hw_handler_name) {
615 /*
616 * Increments scsi_dh reference, even when using an
617 * already-attached handler.
618 */
619 r = scsi_dh_attach(q, m->hw_handler_name);
620 if (r == -EBUSY) {
621 /*
622 * Already attached to different hw_handler:
623 * try to reattach with correct one.
624 */
625 scsi_dh_detach(q);
626 r = scsi_dh_attach(q, m->hw_handler_name);
627 }
628
629 if (r < 0) {
630 ti->error = "error attaching hardware handler";
631 dm_put_device(ti, p->path.dev);
632 goto bad;
633 }
634
635 if (m->hw_handler_params) {
636 r = scsi_dh_set_params(q, m->hw_handler_params);
637 if (r < 0) {
638 ti->error = "unable to set hardware "
639 "handler parameters";
640 scsi_dh_detach(q);
641 dm_put_device(ti, p->path.dev);
642 goto bad;
643 }
644 }
645 }
646
647 r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
648 if (r) {
649 dm_put_device(ti, p->path.dev);
650 goto bad;
651 }
652
653 return p;
654
655 bad:
656 free_pgpath(p);
657 return ERR_PTR(r);
658 }
659
660 static struct priority_group *parse_priority_group(struct dm_arg_set *as,
661 struct multipath *m)
662 {
663 static struct dm_arg _args[] = {
664 {1, 1024, "invalid number of paths"},
665 {0, 1024, "invalid number of selector args"}
666 };
667
668 int r;
669 unsigned i, nr_selector_args, nr_args;
670 struct priority_group *pg;
671 struct dm_target *ti = m->ti;
672
673 if (as->argc < 2) {
674 as->argc = 0;
675 ti->error = "not enough priority group arguments";
676 return ERR_PTR(-EINVAL);
677 }
678
679 pg = alloc_priority_group();
680 if (!pg) {
681 ti->error = "couldn't allocate priority group";
682 return ERR_PTR(-ENOMEM);
683 }
684 pg->m = m;
685
686 r = parse_path_selector(as, pg, ti);
687 if (r)
688 goto bad;
689
690 /*
691 * read the paths
692 */
693 r = dm_read_arg(_args, as, &pg->nr_pgpaths, &ti->error);
694 if (r)
695 goto bad;
696
697 r = dm_read_arg(_args + 1, as, &nr_selector_args, &ti->error);
698 if (r)
699 goto bad;
700
701 nr_args = 1 + nr_selector_args;
702 for (i = 0; i < pg->nr_pgpaths; i++) {
703 struct pgpath *pgpath;
704 struct dm_arg_set path_args;
705
706 if (as->argc < nr_args) {
707 ti->error = "not enough path parameters";
708 r = -EINVAL;
709 goto bad;
710 }
711
712 path_args.argc = nr_args;
713 path_args.argv = as->argv;
714
715 pgpath = parse_path(&path_args, &pg->ps, ti);
716 if (IS_ERR(pgpath)) {
717 r = PTR_ERR(pgpath);
718 goto bad;
719 }
720
721 pgpath->pg = pg;
722 list_add_tail(&pgpath->list, &pg->pgpaths);
723 dm_consume_args(as, nr_args);
724 }
725
726 return pg;
727
728 bad:
729 free_priority_group(pg, ti);
730 return ERR_PTR(r);
731 }
732
733 static int parse_hw_handler(struct dm_arg_set *as, struct multipath *m)
734 {
735 unsigned hw_argc;
736 int ret;
737 struct dm_target *ti = m->ti;
738
739 static struct dm_arg _args[] = {
740 {0, 1024, "invalid number of hardware handler args"},
741 };
742
743 if (dm_read_arg_group(_args, as, &hw_argc, &ti->error))
744 return -EINVAL;
745
746 if (!hw_argc)
747 return 0;
748
749 m->hw_handler_name = kstrdup(dm_shift_arg(as), GFP_KERNEL);
750 if (!try_then_request_module(scsi_dh_handler_exist(m->hw_handler_name),
751 "scsi_dh_%s", m->hw_handler_name)) {
752 ti->error = "unknown hardware handler type";
753 ret = -EINVAL;
754 goto fail;
755 }
756
757 if (hw_argc > 1) {
758 char *p;
759 int i, j, len = 4;
760
761 for (i = 0; i <= hw_argc - 2; i++)
762 len += strlen(as->argv[i]) + 1;
763 p = m->hw_handler_params = kzalloc(len, GFP_KERNEL);
764 if (!p) {
765 ti->error = "memory allocation failed";
766 ret = -ENOMEM;
767 goto fail;
768 }
769 j = sprintf(p, "%d", hw_argc - 1);
770 for (i = 0, p+=j+1; i <= hw_argc - 2; i++, p+=j+1)
771 j = sprintf(p, "%s", as->argv[i]);
772 }
773 dm_consume_args(as, hw_argc - 1);
774
775 return 0;
776 fail:
777 kfree(m->hw_handler_name);
778 m->hw_handler_name = NULL;
779 return ret;
780 }
781
782 static int parse_features(struct dm_arg_set *as, struct multipath *m)
783 {
784 int r;
785 unsigned argc;
786 struct dm_target *ti = m->ti;
787 const char *arg_name;
788
789 static struct dm_arg _args[] = {
790 {0, 6, "invalid number of feature args"},
791 {1, 50, "pg_init_retries must be between 1 and 50"},
792 {0, 60000, "pg_init_delay_msecs must be between 0 and 60000"},
793 };
794
795 r = dm_read_arg_group(_args, as, &argc, &ti->error);
796 if (r)
797 return -EINVAL;
798
799 if (!argc)
800 return 0;
801
802 do {
803 arg_name = dm_shift_arg(as);
804 argc--;
805
806 if (!strcasecmp(arg_name, "queue_if_no_path")) {
807 r = queue_if_no_path(m, 1, 0);
808 continue;
809 }
810
811 if (!strcasecmp(arg_name, "retain_attached_hw_handler")) {
812 m->retain_attached_hw_handler = 1;
813 continue;
814 }
815
816 if (!strcasecmp(arg_name, "pg_init_retries") &&
817 (argc >= 1)) {
818 r = dm_read_arg(_args + 1, as, &m->pg_init_retries, &ti->error);
819 argc--;
820 continue;
821 }
822
823 if (!strcasecmp(arg_name, "pg_init_delay_msecs") &&
824 (argc >= 1)) {
825 r = dm_read_arg(_args + 2, as, &m->pg_init_delay_msecs, &ti->error);
826 argc--;
827 continue;
828 }
829
830 ti->error = "Unrecognised multipath feature request";
831 r = -EINVAL;
832 } while (argc && !r);
833
834 return r;
835 }
836
837 static int multipath_ctr(struct dm_target *ti, unsigned int argc,
838 char **argv)
839 {
840 /* target arguments */
841 static struct dm_arg _args[] = {
842 {0, 1024, "invalid number of priority groups"},
843 {0, 1024, "invalid initial priority group number"},
844 };
845
846 int r;
847 struct multipath *m;
848 struct dm_arg_set as;
849 unsigned pg_count = 0;
850 unsigned next_pg_num;
851
852 as.argc = argc;
853 as.argv = argv;
854
855 m = alloc_multipath(ti);
856 if (!m) {
857 ti->error = "can't allocate multipath";
858 return -EINVAL;
859 }
860
861 r = parse_features(&as, m);
862 if (r)
863 goto bad;
864
865 r = parse_hw_handler(&as, m);
866 if (r)
867 goto bad;
868
869 r = dm_read_arg(_args, &as, &m->nr_priority_groups, &ti->error);
870 if (r)
871 goto bad;
872
873 r = dm_read_arg(_args + 1, &as, &next_pg_num, &ti->error);
874 if (r)
875 goto bad;
876
877 if ((!m->nr_priority_groups && next_pg_num) ||
878 (m->nr_priority_groups && !next_pg_num)) {
879 ti->error = "invalid initial priority group";
880 r = -EINVAL;
881 goto bad;
882 }
883
884 /* parse the priority groups */
885 while (as.argc) {
886 struct priority_group *pg;
887
888 pg = parse_priority_group(&as, m);
889 if (IS_ERR(pg)) {
890 r = PTR_ERR(pg);
891 goto bad;
892 }
893
894 m->nr_valid_paths += pg->nr_pgpaths;
895 list_add_tail(&pg->list, &m->priority_groups);
896 pg_count++;
897 pg->pg_num = pg_count;
898 if (!--next_pg_num)
899 m->next_pg = pg;
900 }
901
902 if (pg_count != m->nr_priority_groups) {
903 ti->error = "priority group count mismatch";
904 r = -EINVAL;
905 goto bad;
906 }
907
908 ti->num_flush_requests = 1;
909 ti->num_discard_requests = 1;
910
911 return 0;
912
913 bad:
914 free_multipath(m);
915 return r;
916 }
917
918 static void multipath_wait_for_pg_init_completion(struct multipath *m)
919 {
920 DECLARE_WAITQUEUE(wait, current);
921 unsigned long flags;
922
923 add_wait_queue(&m->pg_init_wait, &wait);
924
925 while (1) {
926 set_current_state(TASK_UNINTERRUPTIBLE);
927
928 spin_lock_irqsave(&m->lock, flags);
929 if (!m->pg_init_in_progress) {
930 spin_unlock_irqrestore(&m->lock, flags);
931 break;
932 }
933 spin_unlock_irqrestore(&m->lock, flags);
934
935 io_schedule();
936 }
937 set_current_state(TASK_RUNNING);
938
939 remove_wait_queue(&m->pg_init_wait, &wait);
940 }
941
942 static void flush_multipath_work(struct multipath *m)
943 {
944 flush_workqueue(kmpath_handlerd);
945 multipath_wait_for_pg_init_completion(m);
946 flush_workqueue(kmultipathd);
947 flush_work(&m->trigger_event);
948 }
949
950 static void multipath_dtr(struct dm_target *ti)
951 {
952 struct multipath *m = ti->private;
953
954 flush_multipath_work(m);
955 free_multipath(m);
956 }
957
958 /*
959 * Map cloned requests
960 */
961 static int multipath_map(struct dm_target *ti, struct request *clone,
962 union map_info *map_context)
963 {
964 int r;
965 struct multipath *m = (struct multipath *) ti->private;
966
967 if (set_mapinfo(m, map_context) < 0)
968 /* ENOMEM, requeue */
969 return DM_MAPIO_REQUEUE;
970
971 clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
972 r = map_io(m, clone, map_context, 0);
973 if (r < 0 || r == DM_MAPIO_REQUEUE)
974 clear_mapinfo(m, map_context);
975
976 return r;
977 }
978
979 /*
980 * Take a path out of use.
981 */
982 static int fail_path(struct pgpath *pgpath)
983 {
984 unsigned long flags;
985 struct multipath *m = pgpath->pg->m;
986
987 spin_lock_irqsave(&m->lock, flags);
988
989 if (!pgpath->is_active)
990 goto out;
991
992 DMWARN("Failing path %s.", pgpath->path.dev->name);
993
994 pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
995 pgpath->is_active = 0;
996 pgpath->fail_count++;
997
998 m->nr_valid_paths--;
999
1000 if (pgpath == m->current_pgpath)
1001 m->current_pgpath = NULL;
1002
1003 dm_path_uevent(DM_UEVENT_PATH_FAILED, m->ti,
1004 pgpath->path.dev->name, m->nr_valid_paths);
1005
1006 schedule_work(&m->trigger_event);
1007
1008 out:
1009 spin_unlock_irqrestore(&m->lock, flags);
1010
1011 return 0;
1012 }
1013
1014 /*
1015 * Reinstate a previously-failed path
1016 */
1017 static int reinstate_path(struct pgpath *pgpath)
1018 {
1019 int r = 0;
1020 unsigned long flags;
1021 struct multipath *m = pgpath->pg->m;
1022
1023 spin_lock_irqsave(&m->lock, flags);
1024
1025 if (pgpath->is_active)
1026 goto out;
1027
1028 if (!pgpath->pg->ps.type->reinstate_path) {
1029 DMWARN("Reinstate path not supported by path selector %s",
1030 pgpath->pg->ps.type->name);
1031 r = -EINVAL;
1032 goto out;
1033 }
1034
1035 r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
1036 if (r)
1037 goto out;
1038
1039 pgpath->is_active = 1;
1040
1041 if (!m->nr_valid_paths++ && m->queue_size) {
1042 m->current_pgpath = NULL;
1043 queue_work(kmultipathd, &m->process_queued_ios);
1044 } else if (m->hw_handler_name && (m->current_pg == pgpath->pg)) {
1045 if (queue_work(kmpath_handlerd, &pgpath->activate_path.work))
1046 m->pg_init_in_progress++;
1047 }
1048
1049 dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti,
1050 pgpath->path.dev->name, m->nr_valid_paths);
1051
1052 schedule_work(&m->trigger_event);
1053
1054 out:
1055 spin_unlock_irqrestore(&m->lock, flags);
1056
1057 return r;
1058 }
1059
1060 /*
1061 * Fail or reinstate all paths that match the provided struct dm_dev.
1062 */
1063 static int action_dev(struct multipath *m, struct dm_dev *dev,
1064 action_fn action)
1065 {
1066 int r = -EINVAL;
1067 struct pgpath *pgpath;
1068 struct priority_group *pg;
1069
1070 list_for_each_entry(pg, &m->priority_groups, list) {
1071 list_for_each_entry(pgpath, &pg->pgpaths, list) {
1072 if (pgpath->path.dev == dev)
1073 r = action(pgpath);
1074 }
1075 }
1076
1077 return r;
1078 }
1079
1080 /*
1081 * Temporarily try to avoid having to use the specified PG
1082 */
1083 static void bypass_pg(struct multipath *m, struct priority_group *pg,
1084 int bypassed)
1085 {
1086 unsigned long flags;
1087
1088 spin_lock_irqsave(&m->lock, flags);
1089
1090 pg->bypassed = bypassed;
1091 m->current_pgpath = NULL;
1092 m->current_pg = NULL;
1093
1094 spin_unlock_irqrestore(&m->lock, flags);
1095
1096 schedule_work(&m->trigger_event);
1097 }
1098
1099 /*
1100 * Switch to using the specified PG from the next I/O that gets mapped
1101 */
1102 static int switch_pg_num(struct multipath *m, const char *pgstr)
1103 {
1104 struct priority_group *pg;
1105 unsigned pgnum;
1106 unsigned long flags;
1107 char dummy;
1108
1109 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1110 (pgnum > m->nr_priority_groups)) {
1111 DMWARN("invalid PG number supplied to switch_pg_num");
1112 return -EINVAL;
1113 }
1114
1115 spin_lock_irqsave(&m->lock, flags);
1116 list_for_each_entry(pg, &m->priority_groups, list) {
1117 pg->bypassed = 0;
1118 if (--pgnum)
1119 continue;
1120
1121 m->current_pgpath = NULL;
1122 m->current_pg = NULL;
1123 m->next_pg = pg;
1124 }
1125 spin_unlock_irqrestore(&m->lock, flags);
1126
1127 schedule_work(&m->trigger_event);
1128 return 0;
1129 }
1130
1131 /*
1132 * Set/clear bypassed status of a PG.
1133 * PGs are numbered upwards from 1 in the order they were declared.
1134 */
1135 static int bypass_pg_num(struct multipath *m, const char *pgstr, int bypassed)
1136 {
1137 struct priority_group *pg;
1138 unsigned pgnum;
1139 char dummy;
1140
1141 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1142 (pgnum > m->nr_priority_groups)) {
1143 DMWARN("invalid PG number supplied to bypass_pg");
1144 return -EINVAL;
1145 }
1146
1147 list_for_each_entry(pg, &m->priority_groups, list) {
1148 if (!--pgnum)
1149 break;
1150 }
1151
1152 bypass_pg(m, pg, bypassed);
1153 return 0;
1154 }
1155
1156 /*
1157 * Should we retry pg_init immediately?
1158 */
1159 static int pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath)
1160 {
1161 unsigned long flags;
1162 int limit_reached = 0;
1163
1164 spin_lock_irqsave(&m->lock, flags);
1165
1166 if (m->pg_init_count <= m->pg_init_retries)
1167 m->pg_init_required = 1;
1168 else
1169 limit_reached = 1;
1170
1171 spin_unlock_irqrestore(&m->lock, flags);
1172
1173 return limit_reached;
1174 }
1175
1176 static void pg_init_done(void *data, int errors)
1177 {
1178 struct pgpath *pgpath = data;
1179 struct priority_group *pg = pgpath->pg;
1180 struct multipath *m = pg->m;
1181 unsigned long flags;
1182 unsigned delay_retry = 0;
1183
1184 /* device or driver problems */
1185 switch (errors) {
1186 case SCSI_DH_OK:
1187 break;
1188 case SCSI_DH_NOSYS:
1189 if (!m->hw_handler_name) {
1190 errors = 0;
1191 break;
1192 }
1193 DMERR("Could not failover the device: Handler scsi_dh_%s "
1194 "Error %d.", m->hw_handler_name, errors);
1195 /*
1196 * Fail path for now, so we do not ping pong
1197 */
1198 fail_path(pgpath);
1199 break;
1200 case SCSI_DH_DEV_TEMP_BUSY:
1201 /*
1202 * Probably doing something like FW upgrade on the
1203 * controller so try the other pg.
1204 */
1205 bypass_pg(m, pg, 1);
1206 break;
1207 case SCSI_DH_RETRY:
1208 /* Wait before retrying. */
1209 delay_retry = 1;
1210 case SCSI_DH_IMM_RETRY:
1211 case SCSI_DH_RES_TEMP_UNAVAIL:
1212 if (pg_init_limit_reached(m, pgpath))
1213 fail_path(pgpath);
1214 errors = 0;
1215 break;
1216 default:
1217 /*
1218 * We probably do not want to fail the path for a device
1219 * error, but this is what the old dm did. In future
1220 * patches we can do more advanced handling.
1221 */
1222 fail_path(pgpath);
1223 }
1224
1225 spin_lock_irqsave(&m->lock, flags);
1226 if (errors) {
1227 if (pgpath == m->current_pgpath) {
1228 DMERR("Could not failover device. Error %d.", errors);
1229 m->current_pgpath = NULL;
1230 m->current_pg = NULL;
1231 }
1232 } else if (!m->pg_init_required)
1233 pg->bypassed = 0;
1234
1235 if (--m->pg_init_in_progress)
1236 /* Activations of other paths are still on going */
1237 goto out;
1238
1239 if (!m->pg_init_required)
1240 m->queue_io = 0;
1241
1242 m->pg_init_delay_retry = delay_retry;
1243 queue_work(kmultipathd, &m->process_queued_ios);
1244
1245 /*
1246 * Wake up any thread waiting to suspend.
1247 */
1248 wake_up(&m->pg_init_wait);
1249
1250 out:
1251 spin_unlock_irqrestore(&m->lock, flags);
1252 }
1253
1254 static void activate_path(struct work_struct *work)
1255 {
1256 struct pgpath *pgpath =
1257 container_of(work, struct pgpath, activate_path.work);
1258
1259 scsi_dh_activate(bdev_get_queue(pgpath->path.dev->bdev),
1260 pg_init_done, pgpath);
1261 }
1262
1263 /*
1264 * end_io handling
1265 */
1266 static int do_end_io(struct multipath *m, struct request *clone,
1267 int error, struct dm_mpath_io *mpio)
1268 {
1269 /*
1270 * We don't queue any clone request inside the multipath target
1271 * during end I/O handling, since those clone requests don't have
1272 * bio clones. If we queue them inside the multipath target,
1273 * we need to make bio clones, that requires memory allocation.
1274 * (See drivers/md/dm.c:end_clone_bio() about why the clone requests
1275 * don't have bio clones.)
1276 * Instead of queueing the clone request here, we queue the original
1277 * request into dm core, which will remake a clone request and
1278 * clone bios for it and resubmit it later.
1279 */
1280 int r = DM_ENDIO_REQUEUE;
1281 unsigned long flags;
1282
1283 if (!error && !clone->errors)
1284 return 0; /* I/O complete */
1285
1286 if (error == -EOPNOTSUPP || error == -EREMOTEIO || error == -EILSEQ)
1287 return error;
1288
1289 if (mpio->pgpath)
1290 fail_path(mpio->pgpath);
1291
1292 spin_lock_irqsave(&m->lock, flags);
1293 if (!m->nr_valid_paths) {
1294 if (!m->queue_if_no_path) {
1295 if (!__must_push_back(m))
1296 r = -EIO;
1297 } else {
1298 if (error == -EBADE)
1299 r = error;
1300 }
1301 }
1302 spin_unlock_irqrestore(&m->lock, flags);
1303
1304 return r;
1305 }
1306
1307 static int multipath_end_io(struct dm_target *ti, struct request *clone,
1308 int error, union map_info *map_context)
1309 {
1310 struct multipath *m = ti->private;
1311 struct dm_mpath_io *mpio = map_context->ptr;
1312 struct pgpath *pgpath;
1313 struct path_selector *ps;
1314 int r;
1315
1316 BUG_ON(!mpio);
1317
1318 r = do_end_io(m, clone, error, mpio);
1319 pgpath = mpio->pgpath;
1320 if (pgpath) {
1321 ps = &pgpath->pg->ps;
1322 if (ps->type->end_io)
1323 ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
1324 }
1325 clear_mapinfo(m, map_context);
1326
1327 return r;
1328 }
1329
1330 /*
1331 * Suspend can't complete until all the I/O is processed so if
1332 * the last path fails we must error any remaining I/O.
1333 * Note that if the freeze_bdev fails while suspending, the
1334 * queue_if_no_path state is lost - userspace should reset it.
1335 */
1336 static void multipath_presuspend(struct dm_target *ti)
1337 {
1338 struct multipath *m = (struct multipath *) ti->private;
1339
1340 queue_if_no_path(m, 0, 1);
1341 }
1342
1343 static void multipath_postsuspend(struct dm_target *ti)
1344 {
1345 struct multipath *m = ti->private;
1346
1347 mutex_lock(&m->work_mutex);
1348 flush_multipath_work(m);
1349 mutex_unlock(&m->work_mutex);
1350 }
1351
1352 /*
1353 * Restore the queue_if_no_path setting.
1354 */
1355 static void multipath_resume(struct dm_target *ti)
1356 {
1357 struct multipath *m = (struct multipath *) ti->private;
1358 unsigned long flags;
1359
1360 spin_lock_irqsave(&m->lock, flags);
1361 m->queue_if_no_path = m->saved_queue_if_no_path;
1362 spin_unlock_irqrestore(&m->lock, flags);
1363 }
1364
1365 /*
1366 * Info output has the following format:
1367 * num_multipath_feature_args [multipath_feature_args]*
1368 * num_handler_status_args [handler_status_args]*
1369 * num_groups init_group_number
1370 * [A|D|E num_ps_status_args [ps_status_args]*
1371 * num_paths num_selector_args
1372 * [path_dev A|F fail_count [selector_args]* ]+ ]+
1373 *
1374 * Table output has the following format (identical to the constructor string):
1375 * num_feature_args [features_args]*
1376 * num_handler_args hw_handler [hw_handler_args]*
1377 * num_groups init_group_number
1378 * [priority selector-name num_ps_args [ps_args]*
1379 * num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
1380 */
1381 static int multipath_status(struct dm_target *ti, status_type_t type,
1382 unsigned status_flags, char *result, unsigned maxlen)
1383 {
1384 int sz = 0;
1385 unsigned long flags;
1386 struct multipath *m = (struct multipath *) ti->private;
1387 struct priority_group *pg;
1388 struct pgpath *p;
1389 unsigned pg_num;
1390 char state;
1391
1392 spin_lock_irqsave(&m->lock, flags);
1393
1394 /* Features */
1395 if (type == STATUSTYPE_INFO)
1396 DMEMIT("2 %u %u ", m->queue_size, m->pg_init_count);
1397 else {
1398 DMEMIT("%u ", m->queue_if_no_path +
1399 (m->pg_init_retries > 0) * 2 +
1400 (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT) * 2 +
1401 m->retain_attached_hw_handler);
1402 if (m->queue_if_no_path)
1403 DMEMIT("queue_if_no_path ");
1404 if (m->pg_init_retries)
1405 DMEMIT("pg_init_retries %u ", m->pg_init_retries);
1406 if (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT)
1407 DMEMIT("pg_init_delay_msecs %u ", m->pg_init_delay_msecs);
1408 if (m->retain_attached_hw_handler)
1409 DMEMIT("retain_attached_hw_handler ");
1410 }
1411
1412 if (!m->hw_handler_name || type == STATUSTYPE_INFO)
1413 DMEMIT("0 ");
1414 else
1415 DMEMIT("1 %s ", m->hw_handler_name);
1416
1417 DMEMIT("%u ", m->nr_priority_groups);
1418
1419 if (m->next_pg)
1420 pg_num = m->next_pg->pg_num;
1421 else if (m->current_pg)
1422 pg_num = m->current_pg->pg_num;
1423 else
1424 pg_num = (m->nr_priority_groups ? 1 : 0);
1425
1426 DMEMIT("%u ", pg_num);
1427
1428 switch (type) {
1429 case STATUSTYPE_INFO:
1430 list_for_each_entry(pg, &m->priority_groups, list) {
1431 if (pg->bypassed)
1432 state = 'D'; /* Disabled */
1433 else if (pg == m->current_pg)
1434 state = 'A'; /* Currently Active */
1435 else
1436 state = 'E'; /* Enabled */
1437
1438 DMEMIT("%c ", state);
1439
1440 if (pg->ps.type->status)
1441 sz += pg->ps.type->status(&pg->ps, NULL, type,
1442 result + sz,
1443 maxlen - sz);
1444 else
1445 DMEMIT("0 ");
1446
1447 DMEMIT("%u %u ", pg->nr_pgpaths,
1448 pg->ps.type->info_args);
1449
1450 list_for_each_entry(p, &pg->pgpaths, list) {
1451 DMEMIT("%s %s %u ", p->path.dev->name,
1452 p->is_active ? "A" : "F",
1453 p->fail_count);
1454 if (pg->ps.type->status)
1455 sz += pg->ps.type->status(&pg->ps,
1456 &p->path, type, result + sz,
1457 maxlen - sz);
1458 }
1459 }
1460 break;
1461
1462 case STATUSTYPE_TABLE:
1463 list_for_each_entry(pg, &m->priority_groups, list) {
1464 DMEMIT("%s ", pg->ps.type->name);
1465
1466 if (pg->ps.type->status)
1467 sz += pg->ps.type->status(&pg->ps, NULL, type,
1468 result + sz,
1469 maxlen - sz);
1470 else
1471 DMEMIT("0 ");
1472
1473 DMEMIT("%u %u ", pg->nr_pgpaths,
1474 pg->ps.type->table_args);
1475
1476 list_for_each_entry(p, &pg->pgpaths, list) {
1477 DMEMIT("%s ", p->path.dev->name);
1478 if (pg->ps.type->status)
1479 sz += pg->ps.type->status(&pg->ps,
1480 &p->path, type, result + sz,
1481 maxlen - sz);
1482 }
1483 }
1484 break;
1485 }
1486
1487 spin_unlock_irqrestore(&m->lock, flags);
1488
1489 return 0;
1490 }
1491
1492 static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
1493 {
1494 int r = -EINVAL;
1495 struct dm_dev *dev;
1496 struct multipath *m = (struct multipath *) ti->private;
1497 action_fn action;
1498
1499 mutex_lock(&m->work_mutex);
1500
1501 if (dm_suspended(ti)) {
1502 r = -EBUSY;
1503 goto out;
1504 }
1505
1506 if (argc == 1) {
1507 if (!strcasecmp(argv[0], "queue_if_no_path")) {
1508 r = queue_if_no_path(m, 1, 0);
1509 goto out;
1510 } else if (!strcasecmp(argv[0], "fail_if_no_path")) {
1511 r = queue_if_no_path(m, 0, 0);
1512 goto out;
1513 }
1514 }
1515
1516 if (argc != 2) {
1517 DMWARN("Unrecognised multipath message received.");
1518 goto out;
1519 }
1520
1521 if (!strcasecmp(argv[0], "disable_group")) {
1522 r = bypass_pg_num(m, argv[1], 1);
1523 goto out;
1524 } else if (!strcasecmp(argv[0], "enable_group")) {
1525 r = bypass_pg_num(m, argv[1], 0);
1526 goto out;
1527 } else if (!strcasecmp(argv[0], "switch_group")) {
1528 r = switch_pg_num(m, argv[1]);
1529 goto out;
1530 } else if (!strcasecmp(argv[0], "reinstate_path"))
1531 action = reinstate_path;
1532 else if (!strcasecmp(argv[0], "fail_path"))
1533 action = fail_path;
1534 else {
1535 DMWARN("Unrecognised multipath message received.");
1536 goto out;
1537 }
1538
1539 r = dm_get_device(ti, argv[1], dm_table_get_mode(ti->table), &dev);
1540 if (r) {
1541 DMWARN("message: error getting device %s",
1542 argv[1]);
1543 goto out;
1544 }
1545
1546 r = action_dev(m, dev, action);
1547
1548 dm_put_device(ti, dev);
1549
1550 out:
1551 mutex_unlock(&m->work_mutex);
1552 return r;
1553 }
1554
1555 static int multipath_ioctl(struct dm_target *ti, unsigned int cmd,
1556 unsigned long arg)
1557 {
1558 struct multipath *m = ti->private;
1559 struct pgpath *pgpath;
1560 struct block_device *bdev;
1561 fmode_t mode;
1562 unsigned long flags;
1563 int r;
1564
1565 again:
1566 bdev = NULL;
1567 mode = 0;
1568 r = 0;
1569
1570 spin_lock_irqsave(&m->lock, flags);
1571
1572 if (!m->current_pgpath)
1573 __choose_pgpath(m, 0);
1574
1575 pgpath = m->current_pgpath;
1576
1577 if (pgpath) {
1578 bdev = pgpath->path.dev->bdev;
1579 mode = pgpath->path.dev->mode;
1580 }
1581
1582 if ((pgpath && m->queue_io) || (!pgpath && m->queue_if_no_path))
1583 r = -EAGAIN;
1584 else if (!bdev)
1585 r = -EIO;
1586
1587 spin_unlock_irqrestore(&m->lock, flags);
1588
1589 /*
1590 * Only pass ioctls through if the device sizes match exactly.
1591 */
1592 if (!r && ti->len != i_size_read(bdev->bd_inode) >> SECTOR_SHIFT)
1593 r = scsi_verify_blk_ioctl(NULL, cmd);
1594
1595 if (r == -EAGAIN && !fatal_signal_pending(current)) {
1596 queue_work(kmultipathd, &m->process_queued_ios);
1597 msleep(10);
1598 goto again;
1599 }
1600
1601 return r ? : __blkdev_driver_ioctl(bdev, mode, cmd, arg);
1602 }
1603
1604 static int multipath_iterate_devices(struct dm_target *ti,
1605 iterate_devices_callout_fn fn, void *data)
1606 {
1607 struct multipath *m = ti->private;
1608 struct priority_group *pg;
1609 struct pgpath *p;
1610 int ret = 0;
1611
1612 list_for_each_entry(pg, &m->priority_groups, list) {
1613 list_for_each_entry(p, &pg->pgpaths, list) {
1614 ret = fn(ti, p->path.dev, ti->begin, ti->len, data);
1615 if (ret)
1616 goto out;
1617 }
1618 }
1619
1620 out:
1621 return ret;
1622 }
1623
1624 static int __pgpath_busy(struct pgpath *pgpath)
1625 {
1626 struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
1627
1628 return dm_underlying_device_busy(q);
1629 }
1630
1631 /*
1632 * We return "busy", only when we can map I/Os but underlying devices
1633 * are busy (so even if we map I/Os now, the I/Os will wait on
1634 * the underlying queue).
1635 * In other words, if we want to kill I/Os or queue them inside us
1636 * due to map unavailability, we don't return "busy". Otherwise,
1637 * dm core won't give us the I/Os and we can't do what we want.
1638 */
1639 static int multipath_busy(struct dm_target *ti)
1640 {
1641 int busy = 0, has_active = 0;
1642 struct multipath *m = ti->private;
1643 struct priority_group *pg;
1644 struct pgpath *pgpath;
1645 unsigned long flags;
1646
1647 spin_lock_irqsave(&m->lock, flags);
1648
1649 /* Guess which priority_group will be used at next mapping time */
1650 if (unlikely(!m->current_pgpath && m->next_pg))
1651 pg = m->next_pg;
1652 else if (likely(m->current_pg))
1653 pg = m->current_pg;
1654 else
1655 /*
1656 * We don't know which pg will be used at next mapping time.
1657 * We don't call __choose_pgpath() here to avoid to trigger
1658 * pg_init just by busy checking.
1659 * So we don't know whether underlying devices we will be using
1660 * at next mapping time are busy or not. Just try mapping.
1661 */
1662 goto out;
1663
1664 /*
1665 * If there is one non-busy active path at least, the path selector
1666 * will be able to select it. So we consider such a pg as not busy.
1667 */
1668 busy = 1;
1669 list_for_each_entry(pgpath, &pg->pgpaths, list)
1670 if (pgpath->is_active) {
1671 has_active = 1;
1672
1673 if (!__pgpath_busy(pgpath)) {
1674 busy = 0;
1675 break;
1676 }
1677 }
1678
1679 if (!has_active)
1680 /*
1681 * No active path in this pg, so this pg won't be used and
1682 * the current_pg will be changed at next mapping time.
1683 * We need to try mapping to determine it.
1684 */
1685 busy = 0;
1686
1687 out:
1688 spin_unlock_irqrestore(&m->lock, flags);
1689
1690 return busy;
1691 }
1692
1693 /*-----------------------------------------------------------------
1694 * Module setup
1695 *---------------------------------------------------------------*/
1696 static struct target_type multipath_target = {
1697 .name = "multipath",
1698 .version = {1, 5, 0},
1699 .module = THIS_MODULE,
1700 .ctr = multipath_ctr,
1701 .dtr = multipath_dtr,
1702 .map_rq = multipath_map,
1703 .rq_end_io = multipath_end_io,
1704 .presuspend = multipath_presuspend,
1705 .postsuspend = multipath_postsuspend,
1706 .resume = multipath_resume,
1707 .status = multipath_status,
1708 .message = multipath_message,
1709 .ioctl = multipath_ioctl,
1710 .iterate_devices = multipath_iterate_devices,
1711 .busy = multipath_busy,
1712 };
1713
1714 static int __init dm_multipath_init(void)
1715 {
1716 int r;
1717
1718 /* allocate a slab for the dm_ios */
1719 _mpio_cache = KMEM_CACHE(dm_mpath_io, 0);
1720 if (!_mpio_cache)
1721 return -ENOMEM;
1722
1723 r = dm_register_target(&multipath_target);
1724 if (r < 0) {
1725 DMERR("register failed %d", r);
1726 kmem_cache_destroy(_mpio_cache);
1727 return -EINVAL;
1728 }
1729
1730 kmultipathd = alloc_workqueue("kmpathd", WQ_MEM_RECLAIM, 0);
1731 if (!kmultipathd) {
1732 DMERR("failed to create workqueue kmpathd");
1733 dm_unregister_target(&multipath_target);
1734 kmem_cache_destroy(_mpio_cache);
1735 return -ENOMEM;
1736 }
1737
1738 /*
1739 * A separate workqueue is used to handle the device handlers
1740 * to avoid overloading existing workqueue. Overloading the
1741 * old workqueue would also create a bottleneck in the
1742 * path of the storage hardware device activation.
1743 */
1744 kmpath_handlerd = alloc_ordered_workqueue("kmpath_handlerd",
1745 WQ_MEM_RECLAIM);
1746 if (!kmpath_handlerd) {
1747 DMERR("failed to create workqueue kmpath_handlerd");
1748 destroy_workqueue(kmultipathd);
1749 dm_unregister_target(&multipath_target);
1750 kmem_cache_destroy(_mpio_cache);
1751 return -ENOMEM;
1752 }
1753
1754 DMINFO("version %u.%u.%u loaded",
1755 multipath_target.version[0], multipath_target.version[1],
1756 multipath_target.version[2]);
1757
1758 return r;
1759 }
1760
1761 static void __exit dm_multipath_exit(void)
1762 {
1763 destroy_workqueue(kmpath_handlerd);
1764 destroy_workqueue(kmultipathd);
1765
1766 dm_unregister_target(&multipath_target);
1767 kmem_cache_destroy(_mpio_cache);
1768 }
1769
1770 module_init(dm_multipath_init);
1771 module_exit(dm_multipath_exit);
1772
1773 MODULE_DESCRIPTION(DM_NAME " multipath target");
1774 MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
1775 MODULE_LICENSE("GPL");
Linux kernel - Deliverables
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