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mmc: mediatek: add SD write protect support
[linux-2.6/btrfs-unstable.git] / drivers / md / dm-mpath.c
blobcfa29f574c2a9e1454788a5757471835b254d857
1 /*
2 * Copyright (C) 2003 Sistina Software Limited.
3 * Copyright (C) 2004-2005 Red Hat, Inc. All rights reserved.
4 *
5 * This file is released under the GPL.
6 */
7
8 #include <linux/device-mapper.h>
9
10 #include "dm.h"
11 #include "dm-path-selector.h"
12 #include "dm-uevent.h"
13
14 #include <linux/blkdev.h>
15 #include <linux/ctype.h>
16 #include <linux/init.h>
17 #include <linux/mempool.h>
18 #include <linux/module.h>
19 #include <linux/pagemap.h>
20 #include <linux/slab.h>
21 #include <linux/time.h>
22 #include <linux/workqueue.h>
23 #include <linux/delay.h>
24 #include <scsi/scsi_dh.h>
25 #include <linux/atomic.h>
26
27 #define DM_MSG_PREFIX "multipath"
28 #define DM_PG_INIT_DELAY_MSECS 2000
29 #define DM_PG_INIT_DELAY_DEFAULT ((unsigned) -1)
30
31 /* Path properties */
32 struct pgpath {
33 struct list_head list;
34
35 struct priority_group *pg; /* Owning PG */
36 unsigned is_active; /* Path status */
37 unsigned fail_count; /* Cumulative failure count */
38
39 struct dm_path path;
40 struct delayed_work activate_path;
41 };
42
43 #define path_to_pgpath(__pgp) container_of((__pgp), struct pgpath, path)
44
45 /*
46 * Paths are grouped into Priority Groups and numbered from 1 upwards.
47 * Each has a path selector which controls which path gets used.
48 */
49 struct priority_group {
50 struct list_head list;
51
52 struct multipath *m; /* Owning multipath instance */
53 struct path_selector ps;
54
55 unsigned pg_num; /* Reference number */
56 unsigned bypassed; /* Temporarily bypass this PG? */
57
58 unsigned nr_pgpaths; /* Number of paths in PG */
59 struct list_head pgpaths;
60 };
61
62 /* Multipath context */
63 struct multipath {
64 struct list_head list;
65 struct dm_target *ti;
66
67 const char *hw_handler_name;
68 char *hw_handler_params;
69
70 spinlock_t lock;
71
72 unsigned nr_priority_groups;
73 struct list_head priority_groups;
74
75 wait_queue_head_t pg_init_wait; /* Wait for pg_init completion */
76
77 unsigned pg_init_required; /* pg_init needs calling? */
78 unsigned pg_init_in_progress; /* Only one pg_init allowed at once */
79 unsigned pg_init_delay_retry; /* Delay pg_init retry? */
80
81 unsigned nr_valid_paths; /* Total number of usable paths */
82 struct pgpath *current_pgpath;
83 struct priority_group *current_pg;
84 struct priority_group *next_pg; /* Switch to this PG if set */
85 unsigned repeat_count; /* I/Os left before calling PS again */
86
87 unsigned queue_io:1; /* Must we queue all I/O? */
88 unsigned queue_if_no_path:1; /* Queue I/O if last path fails? */
89 unsigned saved_queue_if_no_path:1; /* Saved state during suspension */
90 unsigned retain_attached_hw_handler:1; /* If there's already a hw_handler present, don't change it. */
91 unsigned pg_init_disabled:1; /* pg_init is not currently allowed */
92
93 unsigned pg_init_retries; /* Number of times to retry pg_init */
94 unsigned pg_init_count; /* Number of times pg_init called */
95 unsigned pg_init_delay_msecs; /* Number of msecs before pg_init retry */
96
97 struct work_struct trigger_event;
98
99 /*
100 * We must use a mempool of dm_mpath_io structs so that we
101 * can resubmit bios on error.
102 */
103 mempool_t *mpio_pool;
104
105 struct mutex work_mutex;
106 };
107
108 /*
109 * Context information attached to each bio we process.
110 */
111 struct dm_mpath_io {
112 struct pgpath *pgpath;
113 size_t nr_bytes;
114 };
115
116 typedef int (*action_fn) (struct pgpath *pgpath);
117
118 static struct kmem_cache *_mpio_cache;
119
120 static struct workqueue_struct *kmultipathd, *kmpath_handlerd;
121 static void trigger_event(struct work_struct *work);
122 static void activate_path(struct work_struct *work);
123 static int __pgpath_busy(struct pgpath *pgpath);
124
125
126 /*-----------------------------------------------
127 * Allocation routines
128 *-----------------------------------------------*/
129
130 static struct pgpath *alloc_pgpath(void)
131 {
132 struct pgpath *pgpath = kzalloc(sizeof(*pgpath), GFP_KERNEL);
133
134 if (pgpath) {
135 pgpath->is_active = 1;
136 INIT_DELAYED_WORK(&pgpath->activate_path, activate_path);
137 }
138
139 return pgpath;
140 }
141
142 static void free_pgpath(struct pgpath *pgpath)
143 {
144 kfree(pgpath);
145 }
146
147 static struct priority_group *alloc_priority_group(void)
148 {
149 struct priority_group *pg;
150
151 pg = kzalloc(sizeof(*pg), GFP_KERNEL);
152
153 if (pg)
154 INIT_LIST_HEAD(&pg->pgpaths);
155
156 return pg;
157 }
158
159 static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti)
160 {
161 struct pgpath *pgpath, *tmp;
162
163 list_for_each_entry_safe(pgpath, tmp, pgpaths, list) {
164 list_del(&pgpath->list);
165 dm_put_device(ti, pgpath->path.dev);
166 free_pgpath(pgpath);
167 }
168 }
169
170 static void free_priority_group(struct priority_group *pg,
171 struct dm_target *ti)
172 {
173 struct path_selector *ps = &pg->ps;
174
175 if (ps->type) {
176 ps->type->destroy(ps);
177 dm_put_path_selector(ps->type);
178 }
179
180 free_pgpaths(&pg->pgpaths, ti);
181 kfree(pg);
182 }
183
184 static struct multipath *alloc_multipath(struct dm_target *ti)
185 {
186 struct multipath *m;
187 unsigned min_ios = dm_get_reserved_rq_based_ios();
188
189 m = kzalloc(sizeof(*m), GFP_KERNEL);
190 if (m) {
191 INIT_LIST_HEAD(&m->priority_groups);
192 spin_lock_init(&m->lock);
193 m->queue_io = 1;
194 m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT;
195 INIT_WORK(&m->trigger_event, trigger_event);
196 init_waitqueue_head(&m->pg_init_wait);
197 mutex_init(&m->work_mutex);
198 m->mpio_pool = mempool_create_slab_pool(min_ios, _mpio_cache);
199 if (!m->mpio_pool) {
200 kfree(m);
201 return NULL;
202 }
203 m->ti = ti;
204 ti->private = m;
205 }
206
207 return m;
208 }
209
210 static void free_multipath(struct multipath *m)
211 {
212 struct priority_group *pg, *tmp;
213
214 list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) {
215 list_del(&pg->list);
216 free_priority_group(pg, m->ti);
217 }
218
219 kfree(m->hw_handler_name);
220 kfree(m->hw_handler_params);
221 mempool_destroy(m->mpio_pool);
222 kfree(m);
223 }
224
225 static int set_mapinfo(struct multipath *m, union map_info *info)
226 {
227 struct dm_mpath_io *mpio;
228
229 mpio = mempool_alloc(m->mpio_pool, GFP_ATOMIC);
230 if (!mpio)
231 return -ENOMEM;
232
233 memset(mpio, 0, sizeof(*mpio));
234 info->ptr = mpio;
235
236 return 0;
237 }
238
239 static void clear_mapinfo(struct multipath *m, union map_info *info)
240 {
241 struct dm_mpath_io *mpio = info->ptr;
242
243 info->ptr = NULL;
244 mempool_free(mpio, m->mpio_pool);
245 }
246
247 /*-----------------------------------------------
248 * Path selection
249 *-----------------------------------------------*/
250
251 static int __pg_init_all_paths(struct multipath *m)
252 {
253 struct pgpath *pgpath;
254 unsigned long pg_init_delay = 0;
255
256 if (m->pg_init_in_progress || m->pg_init_disabled)
257 return 0;
258
259 m->pg_init_count++;
260 m->pg_init_required = 0;
261
262 /* Check here to reset pg_init_required */
263 if (!m->current_pg)
264 return 0;
265
266 if (m->pg_init_delay_retry)
267 pg_init_delay = msecs_to_jiffies(m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT ?
268 m->pg_init_delay_msecs : DM_PG_INIT_DELAY_MSECS);
269 list_for_each_entry(pgpath, &m->current_pg->pgpaths, list) {
270 /* Skip failed paths */
271 if (!pgpath->is_active)
272 continue;
273 if (queue_delayed_work(kmpath_handlerd, &pgpath->activate_path,
274 pg_init_delay))
275 m->pg_init_in_progress++;
276 }
277 return m->pg_init_in_progress;
278 }
279
280 static void __switch_pg(struct multipath *m, struct pgpath *pgpath)
281 {
282 m->current_pg = pgpath->pg;
283
284 /* Must we initialise the PG first, and queue I/O till it's ready? */
285 if (m->hw_handler_name) {
286 m->pg_init_required = 1;
287 m->queue_io = 1;
288 } else {
289 m->pg_init_required = 0;
290 m->queue_io = 0;
291 }
292
293 m->pg_init_count = 0;
294 }
295
296 static int __choose_path_in_pg(struct multipath *m, struct priority_group *pg,
297 size_t nr_bytes)
298 {
299 struct dm_path *path;
300
301 path = pg->ps.type->select_path(&pg->ps, &m->repeat_count, nr_bytes);
302 if (!path)
303 return -ENXIO;
304
305 m->current_pgpath = path_to_pgpath(path);
306
307 if (m->current_pg != pg)
308 __switch_pg(m, m->current_pgpath);
309
310 return 0;
311 }
312
313 static void __choose_pgpath(struct multipath *m, size_t nr_bytes)
314 {
315 struct priority_group *pg;
316 unsigned bypassed = 1;
317
318 if (!m->nr_valid_paths) {
319 m->queue_io = 0;
320 goto failed;
321 }
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 /*
377 * Map cloned requests
378 */
379 static int __multipath_map(struct dm_target *ti, struct request *clone,
380 union map_info *map_context,
381 struct request *rq, struct request **__clone)
382 {
383 struct multipath *m = (struct multipath *) ti->private;
384 int r = DM_MAPIO_REQUEUE;
385 size_t nr_bytes = clone ? blk_rq_bytes(clone) : blk_rq_bytes(rq);
386 struct pgpath *pgpath;
387 struct block_device *bdev;
388 struct dm_mpath_io *mpio;
389
390 spin_lock_irq(&m->lock);
391
392 /* Do we need to select a new pgpath? */
393 if (!m->current_pgpath ||
394 (!m->queue_io && (m->repeat_count && --m->repeat_count == 0)))
395 __choose_pgpath(m, nr_bytes);
396
397 pgpath = m->current_pgpath;
398
399 if (!pgpath) {
400 if (!__must_push_back(m))
401 r = -EIO; /* Failed */
402 goto out_unlock;
403 } else if (m->queue_io || m->pg_init_required) {
404 __pg_init_all_paths(m);
405 goto out_unlock;
406 }
407
408 if (set_mapinfo(m, map_context) < 0)
409 /* ENOMEM, requeue */
410 goto out_unlock;
411
412 mpio = map_context->ptr;
413 mpio->pgpath = pgpath;
414 mpio->nr_bytes = nr_bytes;
415
416 bdev = pgpath->path.dev->bdev;
417
418 spin_unlock_irq(&m->lock);
419
420 if (clone) {
421 /* Old request-based interface: allocated clone is passed in */
422 clone->q = bdev_get_queue(bdev);
423 clone->rq_disk = bdev->bd_disk;
424 clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
425 } else {
426 /* blk-mq request-based interface */
427 *__clone = blk_get_request(bdev_get_queue(bdev),
428 rq_data_dir(rq), GFP_ATOMIC);
429 if (IS_ERR(*__clone)) {
430 /* ENOMEM, requeue */
431 clear_mapinfo(m, map_context);
432 return r;
433 }
434 (*__clone)->bio = (*__clone)->biotail = NULL;
435 (*__clone)->rq_disk = bdev->bd_disk;
436 (*__clone)->cmd_flags |= REQ_FAILFAST_TRANSPORT;
437 }
438
439 if (pgpath->pg->ps.type->start_io)
440 pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
441 &pgpath->path,
442 nr_bytes);
443 return DM_MAPIO_REMAPPED;
444
445 out_unlock:
446 spin_unlock_irq(&m->lock);
447
448 return r;
449 }
450
451 static int multipath_map(struct dm_target *ti, struct request *clone,
452 union map_info *map_context)
453 {
454 return __multipath_map(ti, clone, map_context, NULL, NULL);
455 }
456
457 static int multipath_clone_and_map(struct dm_target *ti, struct request *rq,
458 union map_info *map_context,
459 struct request **clone)
460 {
461 return __multipath_map(ti, NULL, map_context, rq, clone);
462 }
463
464 static void multipath_release_clone(struct request *clone)
465 {
466 blk_put_request(clone);
467 }
468
469 /*
470 * If we run out of usable paths, should we queue I/O or error it?
471 */
472 static int queue_if_no_path(struct multipath *m, unsigned queue_if_no_path,
473 unsigned save_old_value)
474 {
475 unsigned long flags;
476
477 spin_lock_irqsave(&m->lock, flags);
478
479 if (save_old_value)
480 m->saved_queue_if_no_path = m->queue_if_no_path;
481 else
482 m->saved_queue_if_no_path = queue_if_no_path;
483 m->queue_if_no_path = queue_if_no_path;
484 spin_unlock_irqrestore(&m->lock, flags);
485
486 if (!queue_if_no_path)
487 dm_table_run_md_queue_async(m->ti->table);
488
489 return 0;
490 }
491
492 /*
493 * An event is triggered whenever a path is taken out of use.
494 * Includes path failure and PG bypass.
495 */
496 static void trigger_event(struct work_struct *work)
497 {
498 struct multipath *m =
499 container_of(work, struct multipath, trigger_event);
500
501 dm_table_event(m->ti->table);
502 }
503
504 /*-----------------------------------------------------------------
505 * Constructor/argument parsing:
506 * <#multipath feature args> [<arg>]*
507 * <#hw_handler args> [hw_handler [<arg>]*]
508 * <#priority groups>
509 * <initial priority group>
510 * [<selector> <#selector args> [<arg>]*
511 * <#paths> <#per-path selector args>
512 * [<path> [<arg>]* ]+ ]+
513 *---------------------------------------------------------------*/
514 static int parse_path_selector(struct dm_arg_set *as, struct priority_group *pg,
515 struct dm_target *ti)
516 {
517 int r;
518 struct path_selector_type *pst;
519 unsigned ps_argc;
520
521 static struct dm_arg _args[] = {
522 {0, 1024, "invalid number of path selector args"},
523 };
524
525 pst = dm_get_path_selector(dm_shift_arg(as));
526 if (!pst) {
527 ti->error = "unknown path selector type";
528 return -EINVAL;
529 }
530
531 r = dm_read_arg_group(_args, as, &ps_argc, &ti->error);
532 if (r) {
533 dm_put_path_selector(pst);
534 return -EINVAL;
535 }
536
537 r = pst->create(&pg->ps, ps_argc, as->argv);
538 if (r) {
539 dm_put_path_selector(pst);
540 ti->error = "path selector constructor failed";
541 return r;
542 }
543
544 pg->ps.type = pst;
545 dm_consume_args(as, ps_argc);
546
547 return 0;
548 }
549
550 static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps,
551 struct dm_target *ti)
552 {
553 int r;
554 struct pgpath *p;
555 struct multipath *m = ti->private;
556 struct request_queue *q = NULL;
557 const char *attached_handler_name;
558
559 /* we need at least a path arg */
560 if (as->argc < 1) {
561 ti->error = "no device given";
562 return ERR_PTR(-EINVAL);
563 }
564
565 p = alloc_pgpath();
566 if (!p)
567 return ERR_PTR(-ENOMEM);
568
569 r = dm_get_device(ti, dm_shift_arg(as), dm_table_get_mode(ti->table),
570 &p->path.dev);
571 if (r) {
572 ti->error = "error getting device";
573 goto bad;
574 }
575
576 if (m->retain_attached_hw_handler || m->hw_handler_name)
577 q = bdev_get_queue(p->path.dev->bdev);
578
579 if (m->retain_attached_hw_handler) {
580 retain:
581 attached_handler_name = scsi_dh_attached_handler_name(q, GFP_KERNEL);
582 if (attached_handler_name) {
583 /*
584 * Reset hw_handler_name to match the attached handler
585 * and clear any hw_handler_params associated with the
586 * ignored handler.
587 *
588 * NB. This modifies the table line to show the actual
589 * handler instead of the original table passed in.
590 */
591 kfree(m->hw_handler_name);
592 m->hw_handler_name = attached_handler_name;
593
594 kfree(m->hw_handler_params);
595 m->hw_handler_params = NULL;
596 }
597 }
598
599 if (m->hw_handler_name) {
600 r = scsi_dh_attach(q, m->hw_handler_name);
601 if (r == -EBUSY) {
602 char b[BDEVNAME_SIZE];
603
604 printk(KERN_INFO "dm-mpath: retaining handler on device %s\n",
605 bdevname(p->path.dev->bdev, b));
606 goto retain;
607 }
608 if (r < 0) {
609 ti->error = "error attaching hardware handler";
610 dm_put_device(ti, p->path.dev);
611 goto bad;
612 }
613
614 if (m->hw_handler_params) {
615 r = scsi_dh_set_params(q, m->hw_handler_params);
616 if (r < 0) {
617 ti->error = "unable to set hardware "
618 "handler parameters";
619 dm_put_device(ti, p->path.dev);
620 goto bad;
621 }
622 }
623 }
624
625 r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
626 if (r) {
627 dm_put_device(ti, p->path.dev);
628 goto bad;
629 }
630
631 return p;
632
633 bad:
634 free_pgpath(p);
635 return ERR_PTR(r);
636 }
637
638 static struct priority_group *parse_priority_group(struct dm_arg_set *as,
639 struct multipath *m)
640 {
641 static struct dm_arg _args[] = {
642 {1, 1024, "invalid number of paths"},
643 {0, 1024, "invalid number of selector args"}
644 };
645
646 int r;
647 unsigned i, nr_selector_args, nr_args;
648 struct priority_group *pg;
649 struct dm_target *ti = m->ti;
650
651 if (as->argc < 2) {
652 as->argc = 0;
653 ti->error = "not enough priority group arguments";
654 return ERR_PTR(-EINVAL);
655 }
656
657 pg = alloc_priority_group();
658 if (!pg) {
659 ti->error = "couldn't allocate priority group";
660 return ERR_PTR(-ENOMEM);
661 }
662 pg->m = m;
663
664 r = parse_path_selector(as, pg, ti);
665 if (r)
666 goto bad;
667
668 /*
669 * read the paths
670 */
671 r = dm_read_arg(_args, as, &pg->nr_pgpaths, &ti->error);
672 if (r)
673 goto bad;
674
675 r = dm_read_arg(_args + 1, as, &nr_selector_args, &ti->error);
676 if (r)
677 goto bad;
678
679 nr_args = 1 + nr_selector_args;
680 for (i = 0; i < pg->nr_pgpaths; i++) {
681 struct pgpath *pgpath;
682 struct dm_arg_set path_args;
683
684 if (as->argc < nr_args) {
685 ti->error = "not enough path parameters";
686 r = -EINVAL;
687 goto bad;
688 }
689
690 path_args.argc = nr_args;
691 path_args.argv = as->argv;
692
693 pgpath = parse_path(&path_args, &pg->ps, ti);
694 if (IS_ERR(pgpath)) {
695 r = PTR_ERR(pgpath);
696 goto bad;
697 }
698
699 pgpath->pg = pg;
700 list_add_tail(&pgpath->list, &pg->pgpaths);
701 dm_consume_args(as, nr_args);
702 }
703
704 return pg;
705
706 bad:
707 free_priority_group(pg, ti);
708 return ERR_PTR(r);
709 }
710
711 static int parse_hw_handler(struct dm_arg_set *as, struct multipath *m)
712 {
713 unsigned hw_argc;
714 int ret;
715 struct dm_target *ti = m->ti;
716
717 static struct dm_arg _args[] = {
718 {0, 1024, "invalid number of hardware handler args"},
719 };
720
721 if (dm_read_arg_group(_args, as, &hw_argc, &ti->error))
722 return -EINVAL;
723
724 if (!hw_argc)
725 return 0;
726
727 m->hw_handler_name = kstrdup(dm_shift_arg(as), GFP_KERNEL);
728
729 if (hw_argc > 1) {
730 char *p;
731 int i, j, len = 4;
732
733 for (i = 0; i <= hw_argc - 2; i++)
734 len += strlen(as->argv[i]) + 1;
735 p = m->hw_handler_params = kzalloc(len, GFP_KERNEL);
736 if (!p) {
737 ti->error = "memory allocation failed";
738 ret = -ENOMEM;
739 goto fail;
740 }
741 j = sprintf(p, "%d", hw_argc - 1);
742 for (i = 0, p+=j+1; i <= hw_argc - 2; i++, p+=j+1)
743 j = sprintf(p, "%s", as->argv[i]);
744 }
745 dm_consume_args(as, hw_argc - 1);
746
747 return 0;
748 fail:
749 kfree(m->hw_handler_name);
750 m->hw_handler_name = NULL;
751 return ret;
752 }
753
754 static int parse_features(struct dm_arg_set *as, struct multipath *m)
755 {
756 int r;
757 unsigned argc;
758 struct dm_target *ti = m->ti;
759 const char *arg_name;
760
761 static struct dm_arg _args[] = {
762 {0, 6, "invalid number of feature args"},
763 {1, 50, "pg_init_retries must be between 1 and 50"},
764 {0, 60000, "pg_init_delay_msecs must be between 0 and 60000"},
765 };
766
767 r = dm_read_arg_group(_args, as, &argc, &ti->error);
768 if (r)
769 return -EINVAL;
770
771 if (!argc)
772 return 0;
773
774 do {
775 arg_name = dm_shift_arg(as);
776 argc--;
777
778 if (!strcasecmp(arg_name, "queue_if_no_path")) {
779 r = queue_if_no_path(m, 1, 0);
780 continue;
781 }
782
783 if (!strcasecmp(arg_name, "retain_attached_hw_handler")) {
784 m->retain_attached_hw_handler = 1;
785 continue;
786 }
787
788 if (!strcasecmp(arg_name, "pg_init_retries") &&
789 (argc >= 1)) {
790 r = dm_read_arg(_args + 1, as, &m->pg_init_retries, &ti->error);
791 argc--;
792 continue;
793 }
794
795 if (!strcasecmp(arg_name, "pg_init_delay_msecs") &&
796 (argc >= 1)) {
797 r = dm_read_arg(_args + 2, as, &m->pg_init_delay_msecs, &ti->error);
798 argc--;
799 continue;
800 }
801
802 ti->error = "Unrecognised multipath feature request";
803 r = -EINVAL;
804 } while (argc && !r);
805
806 return r;
807 }
808
809 static int multipath_ctr(struct dm_target *ti, unsigned int argc,
810 char **argv)
811 {
812 /* target arguments */
813 static struct dm_arg _args[] = {
814 {0, 1024, "invalid number of priority groups"},
815 {0, 1024, "invalid initial priority group number"},
816 };
817
818 int r;
819 struct multipath *m;
820 struct dm_arg_set as;
821 unsigned pg_count = 0;
822 unsigned next_pg_num;
823
824 as.argc = argc;
825 as.argv = argv;
826
827 m = alloc_multipath(ti);
828 if (!m) {
829 ti->error = "can't allocate multipath";
830 return -EINVAL;
831 }
832
833 r = parse_features(&as, m);
834 if (r)
835 goto bad;
836
837 r = parse_hw_handler(&as, m);
838 if (r)
839 goto bad;
840
841 r = dm_read_arg(_args, &as, &m->nr_priority_groups, &ti->error);
842 if (r)
843 goto bad;
844
845 r = dm_read_arg(_args + 1, &as, &next_pg_num, &ti->error);
846 if (r)
847 goto bad;
848
849 if ((!m->nr_priority_groups && next_pg_num) ||
850 (m->nr_priority_groups && !next_pg_num)) {
851 ti->error = "invalid initial priority group";
852 r = -EINVAL;
853 goto bad;
854 }
855
856 /* parse the priority groups */
857 while (as.argc) {
858 struct priority_group *pg;
859
860 pg = parse_priority_group(&as, m);
861 if (IS_ERR(pg)) {
862 r = PTR_ERR(pg);
863 goto bad;
864 }
865
866 m->nr_valid_paths += pg->nr_pgpaths;
867 list_add_tail(&pg->list, &m->priority_groups);
868 pg_count++;
869 pg->pg_num = pg_count;
870 if (!--next_pg_num)
871 m->next_pg = pg;
872 }
873
874 if (pg_count != m->nr_priority_groups) {
875 ti->error = "priority group count mismatch";
876 r = -EINVAL;
877 goto bad;
878 }
879
880 ti->num_flush_bios = 1;
881 ti->num_discard_bios = 1;
882 ti->num_write_same_bios = 1;
883
884 return 0;
885
886 bad:
887 free_multipath(m);
888 return r;
889 }
890
891 static void multipath_wait_for_pg_init_completion(struct multipath *m)
892 {
893 DECLARE_WAITQUEUE(wait, current);
894 unsigned long flags;
895
896 add_wait_queue(&m->pg_init_wait, &wait);
897
898 while (1) {
899 set_current_state(TASK_UNINTERRUPTIBLE);
900
901 spin_lock_irqsave(&m->lock, flags);
902 if (!m->pg_init_in_progress) {
903 spin_unlock_irqrestore(&m->lock, flags);
904 break;
905 }
906 spin_unlock_irqrestore(&m->lock, flags);
907
908 io_schedule();
909 }
910 set_current_state(TASK_RUNNING);
911
912 remove_wait_queue(&m->pg_init_wait, &wait);
913 }
914
915 static void flush_multipath_work(struct multipath *m)
916 {
917 unsigned long flags;
918
919 spin_lock_irqsave(&m->lock, flags);
920 m->pg_init_disabled = 1;
921 spin_unlock_irqrestore(&m->lock, flags);
922
923 flush_workqueue(kmpath_handlerd);
924 multipath_wait_for_pg_init_completion(m);
925 flush_workqueue(kmultipathd);
926 flush_work(&m->trigger_event);
927
928 spin_lock_irqsave(&m->lock, flags);
929 m->pg_init_disabled = 0;
930 spin_unlock_irqrestore(&m->lock, flags);
931 }
932
933 static void multipath_dtr(struct dm_target *ti)
934 {
935 struct multipath *m = ti->private;
936
937 flush_multipath_work(m);
938 free_multipath(m);
939 }
940
941 /*
942 * Take a path out of use.
943 */
944 static int fail_path(struct pgpath *pgpath)
945 {
946 unsigned long flags;
947 struct multipath *m = pgpath->pg->m;
948
949 spin_lock_irqsave(&m->lock, flags);
950
951 if (!pgpath->is_active)
952 goto out;
953
954 DMWARN("Failing path %s.", pgpath->path.dev->name);
955
956 pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
957 pgpath->is_active = 0;
958 pgpath->fail_count++;
959
960 m->nr_valid_paths--;
961
962 if (pgpath == m->current_pgpath)
963 m->current_pgpath = NULL;
964
965 dm_path_uevent(DM_UEVENT_PATH_FAILED, m->ti,
966 pgpath->path.dev->name, m->nr_valid_paths);
967
968 schedule_work(&m->trigger_event);
969
970 out:
971 spin_unlock_irqrestore(&m->lock, flags);
972
973 return 0;
974 }
975
976 /*
977 * Reinstate a previously-failed path
978 */
979 static int reinstate_path(struct pgpath *pgpath)
980 {
981 int r = 0, run_queue = 0;
982 unsigned long flags;
983 struct multipath *m = pgpath->pg->m;
984
985 spin_lock_irqsave(&m->lock, flags);
986
987 if (pgpath->is_active)
988 goto out;
989
990 if (!pgpath->pg->ps.type->reinstate_path) {
991 DMWARN("Reinstate path not supported by path selector %s",
992 pgpath->pg->ps.type->name);
993 r = -EINVAL;
994 goto out;
995 }
996
997 r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
998 if (r)
999 goto out;
1000
1001 pgpath->is_active = 1;
1002
1003 if (!m->nr_valid_paths++) {
1004 m->current_pgpath = NULL;
1005 run_queue = 1;
1006 } else if (m->hw_handler_name && (m->current_pg == pgpath->pg)) {
1007 if (queue_work(kmpath_handlerd, &pgpath->activate_path.work))
1008 m->pg_init_in_progress++;
1009 }
1010
1011 dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti,
1012 pgpath->path.dev->name, m->nr_valid_paths);
1013
1014 schedule_work(&m->trigger_event);
1015
1016 out:
1017 spin_unlock_irqrestore(&m->lock, flags);
1018 if (run_queue)
1019 dm_table_run_md_queue_async(m->ti->table);
1020
1021 return r;
1022 }
1023
1024 /*
1025 * Fail or reinstate all paths that match the provided struct dm_dev.
1026 */
1027 static int action_dev(struct multipath *m, struct dm_dev *dev,
1028 action_fn action)
1029 {
1030 int r = -EINVAL;
1031 struct pgpath *pgpath;
1032 struct priority_group *pg;
1033
1034 list_for_each_entry(pg, &m->priority_groups, list) {
1035 list_for_each_entry(pgpath, &pg->pgpaths, list) {
1036 if (pgpath->path.dev == dev)
1037 r = action(pgpath);
1038 }
1039 }
1040
1041 return r;
1042 }
1043
1044 /*
1045 * Temporarily try to avoid having to use the specified PG
1046 */
1047 static void bypass_pg(struct multipath *m, struct priority_group *pg,
1048 int bypassed)
1049 {
1050 unsigned long flags;
1051
1052 spin_lock_irqsave(&m->lock, flags);
1053
1054 pg->bypassed = bypassed;
1055 m->current_pgpath = NULL;
1056 m->current_pg = NULL;
1057
1058 spin_unlock_irqrestore(&m->lock, flags);
1059
1060 schedule_work(&m->trigger_event);
1061 }
1062
1063 /*
1064 * Switch to using the specified PG from the next I/O that gets mapped
1065 */
1066 static int switch_pg_num(struct multipath *m, const char *pgstr)
1067 {
1068 struct priority_group *pg;
1069 unsigned pgnum;
1070 unsigned long flags;
1071 char dummy;
1072
1073 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1074 (pgnum > m->nr_priority_groups)) {
1075 DMWARN("invalid PG number supplied to switch_pg_num");
1076 return -EINVAL;
1077 }
1078
1079 spin_lock_irqsave(&m->lock, flags);
1080 list_for_each_entry(pg, &m->priority_groups, list) {
1081 pg->bypassed = 0;
1082 if (--pgnum)
1083 continue;
1084
1085 m->current_pgpath = NULL;
1086 m->current_pg = NULL;
1087 m->next_pg = pg;
1088 }
1089 spin_unlock_irqrestore(&m->lock, flags);
1090
1091 schedule_work(&m->trigger_event);
1092 return 0;
1093 }
1094
1095 /*
1096 * Set/clear bypassed status of a PG.
1097 * PGs are numbered upwards from 1 in the order they were declared.
1098 */
1099 static int bypass_pg_num(struct multipath *m, const char *pgstr, int bypassed)
1100 {
1101 struct priority_group *pg;
1102 unsigned pgnum;
1103 char dummy;
1104
1105 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1106 (pgnum > m->nr_priority_groups)) {
1107 DMWARN("invalid PG number supplied to bypass_pg");
1108 return -EINVAL;
1109 }
1110
1111 list_for_each_entry(pg, &m->priority_groups, list) {
1112 if (!--pgnum)
1113 break;
1114 }
1115
1116 bypass_pg(m, pg, bypassed);
1117 return 0;
1118 }
1119
1120 /*
1121 * Should we retry pg_init immediately?
1122 */
1123 static int pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath)
1124 {
1125 unsigned long flags;
1126 int limit_reached = 0;
1127
1128 spin_lock_irqsave(&m->lock, flags);
1129
1130 if (m->pg_init_count <= m->pg_init_retries && !m->pg_init_disabled)
1131 m->pg_init_required = 1;
1132 else
1133 limit_reached = 1;
1134
1135 spin_unlock_irqrestore(&m->lock, flags);
1136
1137 return limit_reached;
1138 }
1139
1140 static void pg_init_done(void *data, int errors)
1141 {
1142 struct pgpath *pgpath = data;
1143 struct priority_group *pg = pgpath->pg;
1144 struct multipath *m = pg->m;
1145 unsigned long flags;
1146 unsigned delay_retry = 0;
1147
1148 /* device or driver problems */
1149 switch (errors) {
1150 case SCSI_DH_OK:
1151 break;
1152 case SCSI_DH_NOSYS:
1153 if (!m->hw_handler_name) {
1154 errors = 0;
1155 break;
1156 }
1157 DMERR("Could not failover the device: Handler scsi_dh_%s "
1158 "Error %d.", m->hw_handler_name, errors);
1159 /*
1160 * Fail path for now, so we do not ping pong
1161 */
1162 fail_path(pgpath);
1163 break;
1164 case SCSI_DH_DEV_TEMP_BUSY:
1165 /*
1166 * Probably doing something like FW upgrade on the
1167 * controller so try the other pg.
1168 */
1169 bypass_pg(m, pg, 1);
1170 break;
1171 case SCSI_DH_RETRY:
1172 /* Wait before retrying. */
1173 delay_retry = 1;
1174 case SCSI_DH_IMM_RETRY:
1175 case SCSI_DH_RES_TEMP_UNAVAIL:
1176 if (pg_init_limit_reached(m, pgpath))
1177 fail_path(pgpath);
1178 errors = 0;
1179 break;
1180 default:
1181 /*
1182 * We probably do not want to fail the path for a device
1183 * error, but this is what the old dm did. In future
1184 * patches we can do more advanced handling.
1185 */
1186 fail_path(pgpath);
1187 }
1188
1189 spin_lock_irqsave(&m->lock, flags);
1190 if (errors) {
1191 if (pgpath == m->current_pgpath) {
1192 DMERR("Could not failover device. Error %d.", errors);
1193 m->current_pgpath = NULL;
1194 m->current_pg = NULL;
1195 }
1196 } else if (!m->pg_init_required)
1197 pg->bypassed = 0;
1198
1199 if (--m->pg_init_in_progress)
1200 /* Activations of other paths are still on going */
1201 goto out;
1202
1203 if (m->pg_init_required) {
1204 m->pg_init_delay_retry = delay_retry;
1205 if (__pg_init_all_paths(m))
1206 goto out;
1207 }
1208 m->queue_io = 0;
1209
1210 /*
1211 * Wake up any thread waiting to suspend.
1212 */
1213 wake_up(&m->pg_init_wait);
1214
1215 out:
1216 spin_unlock_irqrestore(&m->lock, flags);
1217 }
1218
1219 static void activate_path(struct work_struct *work)
1220 {
1221 struct pgpath *pgpath =
1222 container_of(work, struct pgpath, activate_path.work);
1223
1224 if (pgpath->is_active)
1225 scsi_dh_activate(bdev_get_queue(pgpath->path.dev->bdev),
1226 pg_init_done, pgpath);
1227 else
1228 pg_init_done(pgpath, SCSI_DH_DEV_OFFLINED);
1229 }
1230
1231 static int noretry_error(int error)
1232 {
1233 switch (error) {
1234 case -EOPNOTSUPP:
1235 case -EREMOTEIO:
1236 case -EILSEQ:
1237 case -ENODATA:
1238 case -ENOSPC:
1239 return 1;
1240 }
1241
1242 /* Anything else could be a path failure, so should be retried */
1243 return 0;
1244 }
1245
1246 /*
1247 * end_io handling
1248 */
1249 static int do_end_io(struct multipath *m, struct request *clone,
1250 int error, struct dm_mpath_io *mpio)
1251 {
1252 /*
1253 * We don't queue any clone request inside the multipath target
1254 * during end I/O handling, since those clone requests don't have
1255 * bio clones. If we queue them inside the multipath target,
1256 * we need to make bio clones, that requires memory allocation.
1257 * (See drivers/md/dm.c:end_clone_bio() about why the clone requests
1258 * don't have bio clones.)
1259 * Instead of queueing the clone request here, we queue the original
1260 * request into dm core, which will remake a clone request and
1261 * clone bios for it and resubmit it later.
1262 */
1263 int r = DM_ENDIO_REQUEUE;
1264 unsigned long flags;
1265
1266 if (!error && !clone->errors)
1267 return 0; /* I/O complete */
1268
1269 if (noretry_error(error))
1270 return error;
1271
1272 if (mpio->pgpath)
1273 fail_path(mpio->pgpath);
1274
1275 spin_lock_irqsave(&m->lock, flags);
1276 if (!m->nr_valid_paths) {
1277 if (!m->queue_if_no_path) {
1278 if (!__must_push_back(m))
1279 r = -EIO;
1280 } else {
1281 if (error == -EBADE)
1282 r = error;
1283 }
1284 }
1285 spin_unlock_irqrestore(&m->lock, flags);
1286
1287 return r;
1288 }
1289
1290 static int multipath_end_io(struct dm_target *ti, struct request *clone,
1291 int error, union map_info *map_context)
1292 {
1293 struct multipath *m = ti->private;
1294 struct dm_mpath_io *mpio = map_context->ptr;
1295 struct pgpath *pgpath;
1296 struct path_selector *ps;
1297 int r;
1298
1299 BUG_ON(!mpio);
1300
1301 r = do_end_io(m, clone, error, mpio);
1302 pgpath = mpio->pgpath;
1303 if (pgpath) {
1304 ps = &pgpath->pg->ps;
1305 if (ps->type->end_io)
1306 ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
1307 }
1308 clear_mapinfo(m, map_context);
1309
1310 return r;
1311 }
1312
1313 /*
1314 * Suspend can't complete until all the I/O is processed so if
1315 * the last path fails we must error any remaining I/O.
1316 * Note that if the freeze_bdev fails while suspending, the
1317 * queue_if_no_path state is lost - userspace should reset it.
1318 */
1319 static void multipath_presuspend(struct dm_target *ti)
1320 {
1321 struct multipath *m = (struct multipath *) ti->private;
1322
1323 queue_if_no_path(m, 0, 1);
1324 }
1325
1326 static void multipath_postsuspend(struct dm_target *ti)
1327 {
1328 struct multipath *m = ti->private;
1329
1330 mutex_lock(&m->work_mutex);
1331 flush_multipath_work(m);
1332 mutex_unlock(&m->work_mutex);
1333 }
1334
1335 /*
1336 * Restore the queue_if_no_path setting.
1337 */
1338 static void multipath_resume(struct dm_target *ti)
1339 {
1340 struct multipath *m = (struct multipath *) ti->private;
1341 unsigned long flags;
1342
1343 spin_lock_irqsave(&m->lock, flags);
1344 m->queue_if_no_path = m->saved_queue_if_no_path;
1345 spin_unlock_irqrestore(&m->lock, flags);
1346 }
1347
1348 /*
1349 * Info output has the following format:
1350 * num_multipath_feature_args [multipath_feature_args]*
1351 * num_handler_status_args [handler_status_args]*
1352 * num_groups init_group_number
1353 * [A|D|E num_ps_status_args [ps_status_args]*
1354 * num_paths num_selector_args
1355 * [path_dev A|F fail_count [selector_args]* ]+ ]+
1356 *
1357 * Table output has the following format (identical to the constructor string):
1358 * num_feature_args [features_args]*
1359 * num_handler_args hw_handler [hw_handler_args]*
1360 * num_groups init_group_number
1361 * [priority selector-name num_ps_args [ps_args]*
1362 * num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
1363 */
1364 static void multipath_status(struct dm_target *ti, status_type_t type,
1365 unsigned status_flags, char *result, unsigned maxlen)
1366 {
1367 int sz = 0;
1368 unsigned long flags;
1369 struct multipath *m = (struct multipath *) ti->private;
1370 struct priority_group *pg;
1371 struct pgpath *p;
1372 unsigned pg_num;
1373 char state;
1374
1375 spin_lock_irqsave(&m->lock, flags);
1376
1377 /* Features */
1378 if (type == STATUSTYPE_INFO)
1379 DMEMIT("2 %u %u ", m->queue_io, m->pg_init_count);
1380 else {
1381 DMEMIT("%u ", m->queue_if_no_path +
1382 (m->pg_init_retries > 0) * 2 +
1383 (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT) * 2 +
1384 m->retain_attached_hw_handler);
1385 if (m->queue_if_no_path)
1386 DMEMIT("queue_if_no_path ");
1387 if (m->pg_init_retries)
1388 DMEMIT("pg_init_retries %u ", m->pg_init_retries);
1389 if (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT)
1390 DMEMIT("pg_init_delay_msecs %u ", m->pg_init_delay_msecs);
1391 if (m->retain_attached_hw_handler)
1392 DMEMIT("retain_attached_hw_handler ");
1393 }
1394
1395 if (!m->hw_handler_name || type == STATUSTYPE_INFO)
1396 DMEMIT("0 ");
1397 else
1398 DMEMIT("1 %s ", m->hw_handler_name);
1399
1400 DMEMIT("%u ", m->nr_priority_groups);
1401
1402 if (m->next_pg)
1403 pg_num = m->next_pg->pg_num;
1404 else if (m->current_pg)
1405 pg_num = m->current_pg->pg_num;
1406 else
1407 pg_num = (m->nr_priority_groups ? 1 : 0);
1408
1409 DMEMIT("%u ", pg_num);
1410
1411 switch (type) {
1412 case STATUSTYPE_INFO:
1413 list_for_each_entry(pg, &m->priority_groups, list) {
1414 if (pg->bypassed)
1415 state = 'D'; /* Disabled */
1416 else if (pg == m->current_pg)
1417 state = 'A'; /* Currently Active */
1418 else
1419 state = 'E'; /* Enabled */
1420
1421 DMEMIT("%c ", state);
1422
1423 if (pg->ps.type->status)
1424 sz += pg->ps.type->status(&pg->ps, NULL, type,
1425 result + sz,
1426 maxlen - sz);
1427 else
1428 DMEMIT("0 ");
1429
1430 DMEMIT("%u %u ", pg->nr_pgpaths,
1431 pg->ps.type->info_args);
1432
1433 list_for_each_entry(p, &pg->pgpaths, list) {
1434 DMEMIT("%s %s %u ", p->path.dev->name,
1435 p->is_active ? "A" : "F",
1436 p->fail_count);
1437 if (pg->ps.type->status)
1438 sz += pg->ps.type->status(&pg->ps,
1439 &p->path, type, result + sz,
1440 maxlen - sz);
1441 }
1442 }
1443 break;
1444
1445 case STATUSTYPE_TABLE:
1446 list_for_each_entry(pg, &m->priority_groups, list) {
1447 DMEMIT("%s ", pg->ps.type->name);
1448
1449 if (pg->ps.type->status)
1450 sz += pg->ps.type->status(&pg->ps, NULL, type,
1451 result + sz,
1452 maxlen - sz);
1453 else
1454 DMEMIT("0 ");
1455
1456 DMEMIT("%u %u ", pg->nr_pgpaths,
1457 pg->ps.type->table_args);
1458
1459 list_for_each_entry(p, &pg->pgpaths, list) {
1460 DMEMIT("%s ", p->path.dev->name);
1461 if (pg->ps.type->status)
1462 sz += pg->ps.type->status(&pg->ps,
1463 &p->path, type, result + sz,
1464 maxlen - sz);
1465 }
1466 }
1467 break;
1468 }
1469
1470 spin_unlock_irqrestore(&m->lock, flags);
1471 }
1472
1473 static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
1474 {
1475 int r = -EINVAL;
1476 struct dm_dev *dev;
1477 struct multipath *m = (struct multipath *) ti->private;
1478 action_fn action;
1479
1480 mutex_lock(&m->work_mutex);
1481
1482 if (dm_suspended(ti)) {
1483 r = -EBUSY;
1484 goto out;
1485 }
1486
1487 if (argc == 1) {
1488 if (!strcasecmp(argv[0], "queue_if_no_path")) {
1489 r = queue_if_no_path(m, 1, 0);
1490 goto out;
1491 } else if (!strcasecmp(argv[0], "fail_if_no_path")) {
1492 r = queue_if_no_path(m, 0, 0);
1493 goto out;
1494 }
1495 }
1496
1497 if (argc != 2) {
1498 DMWARN("Invalid multipath message arguments. Expected 2 arguments, got %d.", argc);
1499 goto out;
1500 }
1501
1502 if (!strcasecmp(argv[0], "disable_group")) {
1503 r = bypass_pg_num(m, argv[1], 1);
1504 goto out;
1505 } else if (!strcasecmp(argv[0], "enable_group")) {
1506 r = bypass_pg_num(m, argv[1], 0);
1507 goto out;
1508 } else if (!strcasecmp(argv[0], "switch_group")) {
1509 r = switch_pg_num(m, argv[1]);
1510 goto out;
1511 } else if (!strcasecmp(argv[0], "reinstate_path"))
1512 action = reinstate_path;
1513 else if (!strcasecmp(argv[0], "fail_path"))
1514 action = fail_path;
1515 else {
1516 DMWARN("Unrecognised multipath message received: %s", argv[0]);
1517 goto out;
1518 }
1519
1520 r = dm_get_device(ti, argv[1], dm_table_get_mode(ti->table), &dev);
1521 if (r) {
1522 DMWARN("message: error getting device %s",
1523 argv[1]);
1524 goto out;
1525 }
1526
1527 r = action_dev(m, dev, action);
1528
1529 dm_put_device(ti, dev);
1530
1531 out:
1532 mutex_unlock(&m->work_mutex);
1533 return r;
1534 }
1535
1536 static int multipath_prepare_ioctl(struct dm_target *ti,
1537 struct block_device **bdev, fmode_t *mode)
1538 {
1539 struct multipath *m = ti->private;
1540 unsigned long flags;
1541 int r;
1542
1543 spin_lock_irqsave(&m->lock, flags);
1544
1545 if (!m->current_pgpath)
1546 __choose_pgpath(m, 0);
1547
1548 if (m->current_pgpath) {
1549 if (!m->queue_io) {
1550 *bdev = m->current_pgpath->path.dev->bdev;
1551 *mode = m->current_pgpath->path.dev->mode;
1552 r = 0;
1553 } else {
1554 /* pg_init has not started or completed */
1555 r = -ENOTCONN;
1556 }
1557 } else {
1558 /* No path is available */
1559 if (m->queue_if_no_path)
1560 r = -ENOTCONN;
1561 else
1562 r = -EIO;
1563 }
1564
1565 spin_unlock_irqrestore(&m->lock, flags);
1566
1567 if (r == -ENOTCONN) {
1568 spin_lock_irqsave(&m->lock, flags);
1569 if (!m->current_pg) {
1570 /* Path status changed, redo selection */
1571 __choose_pgpath(m, 0);
1572 }
1573 if (m->pg_init_required)
1574 __pg_init_all_paths(m);
1575 spin_unlock_irqrestore(&m->lock, flags);
1576 dm_table_run_md_queue_async(m->ti->table);
1577 }
1578
1579 /*
1580 * Only pass ioctls through if the device sizes match exactly.
1581 */
1582 if (!r && ti->len != i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT)
1583 return 1;
1584 return r;
1585 }
1586
1587 static int multipath_iterate_devices(struct dm_target *ti,
1588 iterate_devices_callout_fn fn, void *data)
1589 {
1590 struct multipath *m = ti->private;
1591 struct priority_group *pg;
1592 struct pgpath *p;
1593 int ret = 0;
1594
1595 list_for_each_entry(pg, &m->priority_groups, list) {
1596 list_for_each_entry(p, &pg->pgpaths, list) {
1597 ret = fn(ti, p->path.dev, ti->begin, ti->len, data);
1598 if (ret)
1599 goto out;
1600 }
1601 }
1602
1603 out:
1604 return ret;
1605 }
1606
1607 static int __pgpath_busy(struct pgpath *pgpath)
1608 {
1609 struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
1610
1611 return blk_lld_busy(q);
1612 }
1613
1614 /*
1615 * We return "busy", only when we can map I/Os but underlying devices
1616 * are busy (so even if we map I/Os now, the I/Os will wait on
1617 * the underlying queue).
1618 * In other words, if we want to kill I/Os or queue them inside us
1619 * due to map unavailability, we don't return "busy". Otherwise,
1620 * dm core won't give us the I/Os and we can't do what we want.
1621 */
1622 static int multipath_busy(struct dm_target *ti)
1623 {
1624 int busy = 0, has_active = 0;
1625 struct multipath *m = ti->private;
1626 struct priority_group *pg;
1627 struct pgpath *pgpath;
1628 unsigned long flags;
1629
1630 spin_lock_irqsave(&m->lock, flags);
1631
1632 /* pg_init in progress or no paths available */
1633 if (m->pg_init_in_progress ||
1634 (!m->nr_valid_paths && m->queue_if_no_path)) {
1635 busy = 1;
1636 goto out;
1637 }
1638 /* Guess which priority_group will be used at next mapping time */
1639 if (unlikely(!m->current_pgpath && m->next_pg))
1640 pg = m->next_pg;
1641 else if (likely(m->current_pg))
1642 pg = m->current_pg;
1643 else
1644 /*
1645 * We don't know which pg will be used at next mapping time.
1646 * We don't call __choose_pgpath() here to avoid to trigger
1647 * pg_init just by busy checking.
1648 * So we don't know whether underlying devices we will be using
1649 * at next mapping time are busy or not. Just try mapping.
1650 */
1651 goto out;
1652
1653 /*
1654 * If there is one non-busy active path at least, the path selector
1655 * will be able to select it. So we consider such a pg as not busy.
1656 */
1657 busy = 1;
1658 list_for_each_entry(pgpath, &pg->pgpaths, list)
1659 if (pgpath->is_active) {
1660 has_active = 1;
1661
1662 if (!__pgpath_busy(pgpath)) {
1663 busy = 0;
1664 break;
1665 }
1666 }
1667
1668 if (!has_active)
1669 /*
1670 * No active path in this pg, so this pg won't be used and
1671 * the current_pg will be changed at next mapping time.
1672 * We need to try mapping to determine it.
1673 */
1674 busy = 0;
1675
1676 out:
1677 spin_unlock_irqrestore(&m->lock, flags);
1678
1679 return busy;
1680 }
1681
1682 /*-----------------------------------------------------------------
1683 * Module setup
1684 *---------------------------------------------------------------*/
1685 static struct target_type multipath_target = {
1686 .name = "multipath",
1687 .version = {1, 10, 0},
1688 .module = THIS_MODULE,
1689 .ctr = multipath_ctr,
1690 .dtr = multipath_dtr,
1691 .map_rq = multipath_map,
1692 .clone_and_map_rq = multipath_clone_and_map,
1693 .release_clone_rq = multipath_release_clone,
1694 .rq_end_io = multipath_end_io,
1695 .presuspend = multipath_presuspend,
1696 .postsuspend = multipath_postsuspend,
1697 .resume = multipath_resume,
1698 .status = multipath_status,
1699 .message = multipath_message,
1700 .prepare_ioctl = multipath_prepare_ioctl,
1701 .iterate_devices = multipath_iterate_devices,
1702 .busy = multipath_busy,
1703 };
1704
1705 static int __init dm_multipath_init(void)
1706 {
1707 int r;
1708
1709 /* allocate a slab for the dm_ios */
1710 _mpio_cache = KMEM_CACHE(dm_mpath_io, 0);
1711 if (!_mpio_cache)
1712 return -ENOMEM;
1713
1714 r = dm_register_target(&multipath_target);
1715 if (r < 0) {
1716 DMERR("register failed %d", r);
1717 r = -EINVAL;
1718 goto bad_register_target;
1719 }
1720
1721 kmultipathd = alloc_workqueue("kmpathd", WQ_MEM_RECLAIM, 0);
1722 if (!kmultipathd) {
1723 DMERR("failed to create workqueue kmpathd");
1724 r = -ENOMEM;
1725 goto bad_alloc_kmultipathd;
1726 }
1727
1728 /*
1729 * A separate workqueue is used to handle the device handlers
1730 * to avoid overloading existing workqueue. Overloading the
1731 * old workqueue would also create a bottleneck in the
1732 * path of the storage hardware device activation.
1733 */
1734 kmpath_handlerd = alloc_ordered_workqueue("kmpath_handlerd",
1735 WQ_MEM_RECLAIM);
1736 if (!kmpath_handlerd) {
1737 DMERR("failed to create workqueue kmpath_handlerd");
1738 r = -ENOMEM;
1739 goto bad_alloc_kmpath_handlerd;
1740 }
1741
1742 DMINFO("version %u.%u.%u loaded",
1743 multipath_target.version[0], multipath_target.version[1],
1744 multipath_target.version[2]);
1745
1746 return 0;
1747
1748 bad_alloc_kmpath_handlerd:
1749 destroy_workqueue(kmultipathd);
1750 bad_alloc_kmultipathd:
1751 dm_unregister_target(&multipath_target);
1752 bad_register_target:
1753 kmem_cache_destroy(_mpio_cache);
1754
1755 return r;
1756 }
1757
1758 static void __exit dm_multipath_exit(void)
1759 {
1760 destroy_workqueue(kmpath_handlerd);
1761 destroy_workqueue(kmultipathd);
1762
1763 dm_unregister_target(&multipath_target);
1764 kmem_cache_destroy(_mpio_cache);
1765 }
1766
1767 module_init(dm_multipath_init);
1768 module_exit(dm_multipath_exit);
1769
1770 MODULE_DESCRIPTION(DM_NAME " multipath target");
1771 MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
1772 MODULE_LICENSE("GPL");
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