projects / GitHub / mt8127 / android_kernel_alcatel_ttab.git / blob
? search:


eb7ddb20fd481bf31667bd1632c29206b30afdd6
[GitHub/mt8127/android_kernel_alcatel_ttab.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 unsigned pg_init_disabled:1; /* pg_init is not currently allowed */
90
91 unsigned pg_init_retries; /* Number of times to retry pg_init */
92 unsigned pg_init_count; /* Number of times pg_init called */
93 unsigned pg_init_delay_msecs; /* Number of msecs before pg_init retry */
94
95 unsigned queue_size;
96 struct work_struct process_queued_ios;
97 struct list_head queued_ios;
98
99 struct work_struct trigger_event;
100
101 /*
102 * We must use a mempool of dm_mpath_io structs so that we
103 * can resubmit bios on error.
104 */
105 mempool_t *mpio_pool;
106
107 struct mutex work_mutex;
108 };
109
110 /*
111 * Context information attached to each bio we process.
112 */
113 struct dm_mpath_io {
114 struct pgpath *pgpath;
115 size_t nr_bytes;
116 };
117
118 typedef int (*action_fn) (struct pgpath *pgpath);
119
120 #define MIN_IOS 256 /* Mempool size */
121
122 static struct kmem_cache *_mpio_cache;
123
124 static struct workqueue_struct *kmultipathd, *kmpath_handlerd;
125 static void process_queued_ios(struct work_struct *work);
126 static void trigger_event(struct work_struct *work);
127 static void activate_path(struct work_struct *work);
128
129
130 /*-----------------------------------------------
131 * Allocation routines
132 *-----------------------------------------------*/
133
134 static struct pgpath *alloc_pgpath(void)
135 {
136 struct pgpath *pgpath = kzalloc(sizeof(*pgpath), GFP_KERNEL);
137
138 if (pgpath) {
139 pgpath->is_active = 1;
140 INIT_DELAYED_WORK(&pgpath->activate_path, activate_path);
141 }
142
143 return pgpath;
144 }
145
146 static void free_pgpath(struct pgpath *pgpath)
147 {
148 kfree(pgpath);
149 }
150
151 static struct priority_group *alloc_priority_group(void)
152 {
153 struct priority_group *pg;
154
155 pg = kzalloc(sizeof(*pg), GFP_KERNEL);
156
157 if (pg)
158 INIT_LIST_HEAD(&pg->pgpaths);
159
160 return pg;
161 }
162
163 static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti)
164 {
165 struct pgpath *pgpath, *tmp;
166 struct multipath *m = ti->private;
167
168 list_for_each_entry_safe(pgpath, tmp, pgpaths, list) {
169 list_del(&pgpath->list);
170 if (m->hw_handler_name)
171 scsi_dh_detach(bdev_get_queue(pgpath->path.dev->bdev));
172 dm_put_device(ti, pgpath->path.dev);
173 free_pgpath(pgpath);
174 }
175 }
176
177 static void free_priority_group(struct priority_group *pg,
178 struct dm_target *ti)
179 {
180 struct path_selector *ps = &pg->ps;
181
182 if (ps->type) {
183 ps->type->destroy(ps);
184 dm_put_path_selector(ps->type);
185 }
186
187 free_pgpaths(&pg->pgpaths, ti);
188 kfree(pg);
189 }
190
191 static struct multipath *alloc_multipath(struct dm_target *ti)
192 {
193 struct multipath *m;
194
195 m = kzalloc(sizeof(*m), GFP_KERNEL);
196 if (m) {
197 INIT_LIST_HEAD(&m->priority_groups);
198 INIT_LIST_HEAD(&m->queued_ios);
199 spin_lock_init(&m->lock);
200 m->queue_io = 1;
201 m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT;
202 INIT_WORK(&m->process_queued_ios, process_queued_ios);
203 INIT_WORK(&m->trigger_event, trigger_event);
204 init_waitqueue_head(&m->pg_init_wait);
205 mutex_init(&m->work_mutex);
206 m->mpio_pool = mempool_create_slab_pool(MIN_IOS, _mpio_cache);
207 if (!m->mpio_pool) {
208 kfree(m);
209 return NULL;
210 }
211 m->ti = ti;
212 ti->private = m;
213 }
214
215 return m;
216 }
217
218 static void free_multipath(struct multipath *m)
219 {
220 struct priority_group *pg, *tmp;
221
222 list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) {
223 list_del(&pg->list);
224 free_priority_group(pg, m->ti);
225 }
226
227 kfree(m->hw_handler_name);
228 kfree(m->hw_handler_params);
229 mempool_destroy(m->mpio_pool);
230 kfree(m);
231 }
232
233 static int set_mapinfo(struct multipath *m, union map_info *info)
234 {
235 struct dm_mpath_io *mpio;
236
237 mpio = mempool_alloc(m->mpio_pool, GFP_ATOMIC);
238 if (!mpio)
239 return -ENOMEM;
240
241 memset(mpio, 0, sizeof(*mpio));
242 info->ptr = mpio;
243
244 return 0;
245 }
246
247 static void clear_mapinfo(struct multipath *m, union map_info *info)
248 {
249 struct dm_mpath_io *mpio = info->ptr;
250
251 info->ptr = NULL;
252 mempool_free(mpio, m->mpio_pool);
253 }
254
255 /*-----------------------------------------------
256 * Path selection
257 *-----------------------------------------------*/
258
259 static void __pg_init_all_paths(struct multipath *m)
260 {
261 struct pgpath *pgpath;
262 unsigned long pg_init_delay = 0;
263
264 m->pg_init_count++;
265 m->pg_init_required = 0;
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 }
278
279 static void __switch_pg(struct multipath *m, struct pgpath *pgpath)
280 {
281 m->current_pg = pgpath->pg;
282
283 /* Must we initialise the PG first, and queue I/O till it's ready? */
284 if (m->hw_handler_name) {
285 m->pg_init_required = 1;
286 m->queue_io = 1;
287 } else {
288 m->pg_init_required = 0;
289 m->queue_io = 0;
290 }
291
292 m->pg_init_count = 0;
293 }
294
295 static int __choose_path_in_pg(struct multipath *m, struct priority_group *pg,
296 size_t nr_bytes)
297 {
298 struct dm_path *path;
299
300 path = pg->ps.type->select_path(&pg->ps, &m->repeat_count, nr_bytes);
301 if (!path)
302 return -ENXIO;
303
304 m->current_pgpath = path_to_pgpath(path);
305
306 if (m->current_pg != pg)
307 __switch_pg(m, m->current_pgpath);
308
309 return 0;
310 }
311
312 static void __choose_pgpath(struct multipath *m, size_t nr_bytes)
313 {
314 struct priority_group *pg;
315 unsigned bypassed = 1;
316
317 if (!m->nr_valid_paths)
318 goto failed;
319
320 /* Were we instructed to switch PG? */
321 if (m->next_pg) {
322 pg = m->next_pg;
323 m->next_pg = NULL;
324 if (!__choose_path_in_pg(m, pg, nr_bytes))
325 return;
326 }
327
328 /* Don't change PG until it has no remaining paths */
329 if (m->current_pg && !__choose_path_in_pg(m, m->current_pg, nr_bytes))
330 return;
331
332 /*
333 * Loop through priority groups until we find a valid path.
334 * First time we skip PGs marked 'bypassed'.
335 * Second time we only try the ones we skipped, but set
336 * pg_init_delay_retry so we do not hammer controllers.
337 */
338 do {
339 list_for_each_entry(pg, &m->priority_groups, list) {
340 if (pg->bypassed == bypassed)
341 continue;
342 if (!__choose_path_in_pg(m, pg, nr_bytes)) {
343 if (!bypassed)
344 m->pg_init_delay_retry = 1;
345 return;
346 }
347 }
348 } while (bypassed--);
349
350 failed:
351 m->current_pgpath = NULL;
352 m->current_pg = NULL;
353 }
354
355 /*
356 * Check whether bios must be queued in the device-mapper core rather
357 * than here in the target.
358 *
359 * m->lock must be held on entry.
360 *
361 * If m->queue_if_no_path and m->saved_queue_if_no_path hold the
362 * same value then we are not between multipath_presuspend()
363 * and multipath_resume() calls and we have no need to check
364 * for the DMF_NOFLUSH_SUSPENDING flag.
365 */
366 static int __must_push_back(struct multipath *m)
367 {
368 return (m->queue_if_no_path != m->saved_queue_if_no_path &&
369 dm_noflush_suspending(m->ti));
370 }
371
372 static int map_io(struct multipath *m, struct request *clone,
373 union map_info *map_context, unsigned was_queued)
374 {
375 int r = DM_MAPIO_REMAPPED;
376 size_t nr_bytes = blk_rq_bytes(clone);
377 unsigned long flags;
378 struct pgpath *pgpath;
379 struct block_device *bdev;
380 struct dm_mpath_io *mpio = map_context->ptr;
381
382 spin_lock_irqsave(&m->lock, flags);
383
384 /* Do we need to select a new pgpath? */
385 if (!m->current_pgpath ||
386 (!m->queue_io && (m->repeat_count && --m->repeat_count == 0)))
387 __choose_pgpath(m, nr_bytes);
388
389 pgpath = m->current_pgpath;
390
391 if (was_queued)
392 m->queue_size--;
393
394 if ((pgpath && m->queue_io) ||
395 (!pgpath && m->queue_if_no_path)) {
396 /* Queue for the daemon to resubmit */
397 list_add_tail(&clone->queuelist, &m->queued_ios);
398 m->queue_size++;
399 if ((m->pg_init_required && !m->pg_init_in_progress) ||
400 !m->queue_io)
401 queue_work(kmultipathd, &m->process_queued_ios);
402 pgpath = NULL;
403 r = DM_MAPIO_SUBMITTED;
404 } else if (pgpath) {
405 bdev = pgpath->path.dev->bdev;
406 clone->q = bdev_get_queue(bdev);
407 clone->rq_disk = bdev->bd_disk;
408 } else if (__must_push_back(m))
409 r = DM_MAPIO_REQUEUE;
410 else
411 r = -EIO; /* Failed */
412
413 mpio->pgpath = pgpath;
414 mpio->nr_bytes = nr_bytes;
415
416 if (r == DM_MAPIO_REMAPPED && pgpath->pg->ps.type->start_io)
417 pgpath->pg->ps.type->start_io(&pgpath->pg->ps, &pgpath->path,
418 nr_bytes);
419
420 spin_unlock_irqrestore(&m->lock, flags);
421
422 return r;
423 }
424
425 /*
426 * If we run out of usable paths, should we queue I/O or error it?
427 */
428 static int queue_if_no_path(struct multipath *m, unsigned queue_if_no_path,
429 unsigned save_old_value)
430 {
431 unsigned long flags;
432
433 spin_lock_irqsave(&m->lock, flags);
434
435 if (save_old_value)
436 m->saved_queue_if_no_path = m->queue_if_no_path;
437 else
438 m->saved_queue_if_no_path = queue_if_no_path;
439 m->queue_if_no_path = queue_if_no_path;
440 if (!m->queue_if_no_path && m->queue_size)
441 queue_work(kmultipathd, &m->process_queued_ios);
442
443 spin_unlock_irqrestore(&m->lock, flags);
444
445 return 0;
446 }
447
448 /*-----------------------------------------------------------------
449 * The multipath daemon is responsible for resubmitting queued ios.
450 *---------------------------------------------------------------*/
451
452 static void dispatch_queued_ios(struct multipath *m)
453 {
454 int r;
455 unsigned long flags;
456 union map_info *info;
457 struct request *clone, *n;
458 LIST_HEAD(cl);
459
460 spin_lock_irqsave(&m->lock, flags);
461 list_splice_init(&m->queued_ios, &cl);
462 spin_unlock_irqrestore(&m->lock, flags);
463
464 list_for_each_entry_safe(clone, n, &cl, queuelist) {
465 list_del_init(&clone->queuelist);
466
467 info = dm_get_rq_mapinfo(clone);
468
469 r = map_io(m, clone, info, 1);
470 if (r < 0) {
471 clear_mapinfo(m, info);
472 dm_kill_unmapped_request(clone, r);
473 } else if (r == DM_MAPIO_REMAPPED)
474 dm_dispatch_request(clone);
475 else if (r == DM_MAPIO_REQUEUE) {
476 clear_mapinfo(m, info);
477 dm_requeue_unmapped_request(clone);
478 }
479 }
480 }
481
482 static void process_queued_ios(struct work_struct *work)
483 {
484 struct multipath *m =
485 container_of(work, struct multipath, process_queued_ios);
486 struct pgpath *pgpath = NULL;
487 unsigned must_queue = 1;
488 unsigned long flags;
489
490 spin_lock_irqsave(&m->lock, flags);
491
492 if (!m->current_pgpath)
493 __choose_pgpath(m, 0);
494
495 pgpath = m->current_pgpath;
496
497 if ((pgpath && !m->queue_io) ||
498 (!pgpath && !m->queue_if_no_path))
499 must_queue = 0;
500
501 if (m->pg_init_required && !m->pg_init_in_progress && pgpath &&
502 !m->pg_init_disabled)
503 __pg_init_all_paths(m);
504
505 spin_unlock_irqrestore(&m->lock, flags);
506 if (!must_queue)
507 dispatch_queued_ios(m);
508 }
509
510 /*
511 * An event is triggered whenever a path is taken out of use.
512 * Includes path failure and PG bypass.
513 */
514 static void trigger_event(struct work_struct *work)
515 {
516 struct multipath *m =
517 container_of(work, struct multipath, trigger_event);
518
519 dm_table_event(m->ti->table);
520 }
521
522 /*-----------------------------------------------------------------
523 * Constructor/argument parsing:
524 * <#multipath feature args> [<arg>]*
525 * <#hw_handler args> [hw_handler [<arg>]*]
526 * <#priority groups>
527 * <initial priority group>
528 * [<selector> <#selector args> [<arg>]*
529 * <#paths> <#per-path selector args>
530 * [<path> [<arg>]* ]+ ]+
531 *---------------------------------------------------------------*/
532 static int parse_path_selector(struct dm_arg_set *as, struct priority_group *pg,
533 struct dm_target *ti)
534 {
535 int r;
536 struct path_selector_type *pst;
537 unsigned ps_argc;
538
539 static struct dm_arg _args[] = {
540 {0, 1024, "invalid number of path selector args"},
541 };
542
543 pst = dm_get_path_selector(dm_shift_arg(as));
544 if (!pst) {
545 ti->error = "unknown path selector type";
546 return -EINVAL;
547 }
548
549 r = dm_read_arg_group(_args, as, &ps_argc, &ti->error);
550 if (r) {
551 dm_put_path_selector(pst);
552 return -EINVAL;
553 }
554
555 r = pst->create(&pg->ps, ps_argc, as->argv);
556 if (r) {
557 dm_put_path_selector(pst);
558 ti->error = "path selector constructor failed";
559 return r;
560 }
561
562 pg->ps.type = pst;
563 dm_consume_args(as, ps_argc);
564
565 return 0;
566 }
567
568 static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps,
569 struct dm_target *ti)
570 {
571 int r;
572 struct pgpath *p;
573 struct multipath *m = ti->private;
574 struct request_queue *q = NULL;
575 const char *attached_handler_name;
576
577 /* we need at least a path arg */
578 if (as->argc < 1) {
579 ti->error = "no device given";
580 return ERR_PTR(-EINVAL);
581 }
582
583 p = alloc_pgpath();
584 if (!p)
585 return ERR_PTR(-ENOMEM);
586
587 r = dm_get_device(ti, dm_shift_arg(as), dm_table_get_mode(ti->table),
588 &p->path.dev);
589 if (r) {
590 ti->error = "error getting device";
591 goto bad;
592 }
593
594 if (m->retain_attached_hw_handler || m->hw_handler_name)
595 q = bdev_get_queue(p->path.dev->bdev);
596
597 if (m->retain_attached_hw_handler) {
598 attached_handler_name = scsi_dh_attached_handler_name(q, GFP_KERNEL);
599 if (attached_handler_name) {
600 /*
601 * Reset hw_handler_name to match the attached handler
602 * and clear any hw_handler_params associated with the
603 * ignored handler.
604 *
605 * NB. This modifies the table line to show the actual
606 * handler instead of the original table passed in.
607 */
608 kfree(m->hw_handler_name);
609 m->hw_handler_name = attached_handler_name;
610
611 kfree(m->hw_handler_params);
612 m->hw_handler_params = NULL;
613 }
614 }
615
616 if (m->hw_handler_name) {
617 /*
618 * Increments scsi_dh reference, even when using an
619 * already-attached handler.
620 */
621 r = scsi_dh_attach(q, m->hw_handler_name);
622 if (r == -EBUSY) {
623 /*
624 * Already attached to different hw_handler:
625 * try to reattach with correct one.
626 */
627 scsi_dh_detach(q);
628 r = scsi_dh_attach(q, m->hw_handler_name);
629 }
630
631 if (r < 0) {
632 ti->error = "error attaching hardware handler";
633 dm_put_device(ti, p->path.dev);
634 goto bad;
635 }
636
637 if (m->hw_handler_params) {
638 r = scsi_dh_set_params(q, m->hw_handler_params);
639 if (r < 0) {
640 ti->error = "unable to set hardware "
641 "handler parameters";
642 scsi_dh_detach(q);
643 dm_put_device(ti, p->path.dev);
644 goto bad;
645 }
646 }
647 }
648
649 r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
650 if (r) {
651 dm_put_device(ti, p->path.dev);
652 goto bad;
653 }
654
655 return p;
656
657 bad:
658 free_pgpath(p);
659 return ERR_PTR(r);
660 }
661
662 static struct priority_group *parse_priority_group(struct dm_arg_set *as,
663 struct multipath *m)
664 {
665 static struct dm_arg _args[] = {
666 {1, 1024, "invalid number of paths"},
667 {0, 1024, "invalid number of selector args"}
668 };
669
670 int r;
671 unsigned i, nr_selector_args, nr_args;
672 struct priority_group *pg;
673 struct dm_target *ti = m->ti;
674
675 if (as->argc < 2) {
676 as->argc = 0;
677 ti->error = "not enough priority group arguments";
678 return ERR_PTR(-EINVAL);
679 }
680
681 pg = alloc_priority_group();
682 if (!pg) {
683 ti->error = "couldn't allocate priority group";
684 return ERR_PTR(-ENOMEM);
685 }
686 pg->m = m;
687
688 r = parse_path_selector(as, pg, ti);
689 if (r)
690 goto bad;
691
692 /*
693 * read the paths
694 */
695 r = dm_read_arg(_args, as, &pg->nr_pgpaths, &ti->error);
696 if (r)
697 goto bad;
698
699 r = dm_read_arg(_args + 1, as, &nr_selector_args, &ti->error);
700 if (r)
701 goto bad;
702
703 nr_args = 1 + nr_selector_args;
704 for (i = 0; i < pg->nr_pgpaths; i++) {
705 struct pgpath *pgpath;
706 struct dm_arg_set path_args;
707
708 if (as->argc < nr_args) {
709 ti->error = "not enough path parameters";
710 r = -EINVAL;
711 goto bad;
712 }
713
714 path_args.argc = nr_args;
715 path_args.argv = as->argv;
716
717 pgpath = parse_path(&path_args, &pg->ps, ti);
718 if (IS_ERR(pgpath)) {
719 r = PTR_ERR(pgpath);
720 goto bad;
721 }
722
723 pgpath->pg = pg;
724 list_add_tail(&pgpath->list, &pg->pgpaths);
725 dm_consume_args(as, nr_args);
726 }
727
728 return pg;
729
730 bad:
731 free_priority_group(pg, ti);
732 return ERR_PTR(r);
733 }
734
735 static int parse_hw_handler(struct dm_arg_set *as, struct multipath *m)
736 {
737 unsigned hw_argc;
738 int ret;
739 struct dm_target *ti = m->ti;
740
741 static struct dm_arg _args[] = {
742 {0, 1024, "invalid number of hardware handler args"},
743 };
744
745 if (dm_read_arg_group(_args, as, &hw_argc, &ti->error))
746 return -EINVAL;
747
748 if (!hw_argc)
749 return 0;
750
751 m->hw_handler_name = kstrdup(dm_shift_arg(as), GFP_KERNEL);
752 if (!try_then_request_module(scsi_dh_handler_exist(m->hw_handler_name),
753 "scsi_dh_%s", m->hw_handler_name)) {
754 ti->error = "unknown hardware handler type";
755 ret = -EINVAL;
756 goto fail;
757 }
758
759 if (hw_argc > 1) {
760 char *p;
761 int i, j, len = 4;
762
763 for (i = 0; i <= hw_argc - 2; i++)
764 len += strlen(as->argv[i]) + 1;
765 p = m->hw_handler_params = kzalloc(len, GFP_KERNEL);
766 if (!p) {
767 ti->error = "memory allocation failed";
768 ret = -ENOMEM;
769 goto fail;
770 }
771 j = sprintf(p, "%d", hw_argc - 1);
772 for (i = 0, p+=j+1; i <= hw_argc - 2; i++, p+=j+1)
773 j = sprintf(p, "%s", as->argv[i]);
774 }
775 dm_consume_args(as, hw_argc - 1);
776
777 return 0;
778 fail:
779 kfree(m->hw_handler_name);
780 m->hw_handler_name = NULL;
781 return ret;
782 }
783
784 static int parse_features(struct dm_arg_set *as, struct multipath *m)
785 {
786 int r;
787 unsigned argc;
788 struct dm_target *ti = m->ti;
789 const char *arg_name;
790
791 static struct dm_arg _args[] = {
792 {0, 6, "invalid number of feature args"},
793 {1, 50, "pg_init_retries must be between 1 and 50"},
794 {0, 60000, "pg_init_delay_msecs must be between 0 and 60000"},
795 };
796
797 r = dm_read_arg_group(_args, as, &argc, &ti->error);
798 if (r)
799 return -EINVAL;
800
801 if (!argc)
802 return 0;
803
804 do {
805 arg_name = dm_shift_arg(as);
806 argc--;
807
808 if (!strcasecmp(arg_name, "queue_if_no_path")) {
809 r = queue_if_no_path(m, 1, 0);
810 continue;
811 }
812
813 if (!strcasecmp(arg_name, "retain_attached_hw_handler")) {
814 m->retain_attached_hw_handler = 1;
815 continue;
816 }
817
818 if (!strcasecmp(arg_name, "pg_init_retries") &&
819 (argc >= 1)) {
820 r = dm_read_arg(_args + 1, as, &m->pg_init_retries, &ti->error);
821 argc--;
822 continue;
823 }
824
825 if (!strcasecmp(arg_name, "pg_init_delay_msecs") &&
826 (argc >= 1)) {
827 r = dm_read_arg(_args + 2, as, &m->pg_init_delay_msecs, &ti->error);
828 argc--;
829 continue;
830 }
831
832 ti->error = "Unrecognised multipath feature request";
833 r = -EINVAL;
834 } while (argc && !r);
835
836 return r;
837 }
838
839 static int multipath_ctr(struct dm_target *ti, unsigned int argc,
840 char **argv)
841 {
842 /* target arguments */
843 static struct dm_arg _args[] = {
844 {0, 1024, "invalid number of priority groups"},
845 {0, 1024, "invalid initial priority group number"},
846 };
847
848 int r;
849 struct multipath *m;
850 struct dm_arg_set as;
851 unsigned pg_count = 0;
852 unsigned next_pg_num;
853
854 as.argc = argc;
855 as.argv = argv;
856
857 m = alloc_multipath(ti);
858 if (!m) {
859 ti->error = "can't allocate multipath";
860 return -EINVAL;
861 }
862
863 r = parse_features(&as, m);
864 if (r)
865 goto bad;
866
867 r = parse_hw_handler(&as, m);
868 if (r)
869 goto bad;
870
871 r = dm_read_arg(_args, &as, &m->nr_priority_groups, &ti->error);
872 if (r)
873 goto bad;
874
875 r = dm_read_arg(_args + 1, &as, &next_pg_num, &ti->error);
876 if (r)
877 goto bad;
878
879 if ((!m->nr_priority_groups && next_pg_num) ||
880 (m->nr_priority_groups && !next_pg_num)) {
881 ti->error = "invalid initial priority group";
882 r = -EINVAL;
883 goto bad;
884 }
885
886 /* parse the priority groups */
887 while (as.argc) {
888 struct priority_group *pg;
889
890 pg = parse_priority_group(&as, m);
891 if (IS_ERR(pg)) {
892 r = PTR_ERR(pg);
893 goto bad;
894 }
895
896 m->nr_valid_paths += pg->nr_pgpaths;
897 list_add_tail(&pg->list, &m->priority_groups);
898 pg_count++;
899 pg->pg_num = pg_count;
900 if (!--next_pg_num)
901 m->next_pg = pg;
902 }
903
904 if (pg_count != m->nr_priority_groups) {
905 ti->error = "priority group count mismatch";
906 r = -EINVAL;
907 goto bad;
908 }
909
910 ti->num_flush_bios = 1;
911 ti->num_discard_bios = 1;
912 ti->num_write_same_bios = 1;
913
914 return 0;
915
916 bad:
917 free_multipath(m);
918 return r;
919 }
920
921 static void multipath_wait_for_pg_init_completion(struct multipath *m)
922 {
923 DECLARE_WAITQUEUE(wait, current);
924 unsigned long flags;
925
926 add_wait_queue(&m->pg_init_wait, &wait);
927
928 while (1) {
929 set_current_state(TASK_UNINTERRUPTIBLE);
930
931 spin_lock_irqsave(&m->lock, flags);
932 if (!m->pg_init_in_progress) {
933 spin_unlock_irqrestore(&m->lock, flags);
934 break;
935 }
936 spin_unlock_irqrestore(&m->lock, flags);
937
938 io_schedule();
939 }
940 set_current_state(TASK_RUNNING);
941
942 remove_wait_queue(&m->pg_init_wait, &wait);
943 }
944
945 static void flush_multipath_work(struct multipath *m)
946 {
947 unsigned long flags;
948
949 spin_lock_irqsave(&m->lock, flags);
950 m->pg_init_disabled = 1;
951 spin_unlock_irqrestore(&m->lock, flags);
952
953 flush_workqueue(kmpath_handlerd);
954 multipath_wait_for_pg_init_completion(m);
955 flush_workqueue(kmultipathd);
956 flush_work(&m->trigger_event);
957
958 spin_lock_irqsave(&m->lock, flags);
959 m->pg_init_disabled = 0;
960 spin_unlock_irqrestore(&m->lock, flags);
961 }
962
963 static void multipath_dtr(struct dm_target *ti)
964 {
965 struct multipath *m = ti->private;
966
967 flush_multipath_work(m);
968 free_multipath(m);
969 }
970
971 /*
972 * Map cloned requests
973 */
974 static int multipath_map(struct dm_target *ti, struct request *clone,
975 union map_info *map_context)
976 {
977 int r;
978 struct multipath *m = (struct multipath *) ti->private;
979
980 if (set_mapinfo(m, map_context) < 0)
981 /* ENOMEM, requeue */
982 return DM_MAPIO_REQUEUE;
983
984 clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
985 r = map_io(m, clone, map_context, 0);
986 if (r < 0 || r == DM_MAPIO_REQUEUE)
987 clear_mapinfo(m, map_context);
988
989 return r;
990 }
991
992 /*
993 * Take a path out of use.
994 */
995 static int fail_path(struct pgpath *pgpath)
996 {
997 unsigned long flags;
998 struct multipath *m = pgpath->pg->m;
999
1000 spin_lock_irqsave(&m->lock, flags);
1001
1002 if (!pgpath->is_active)
1003 goto out;
1004
1005 DMWARN("Failing path %s.", pgpath->path.dev->name);
1006
1007 pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
1008 pgpath->is_active = 0;
1009 pgpath->fail_count++;
1010
1011 m->nr_valid_paths--;
1012
1013 if (pgpath == m->current_pgpath)
1014 m->current_pgpath = NULL;
1015
1016 dm_path_uevent(DM_UEVENT_PATH_FAILED, m->ti,
1017 pgpath->path.dev->name, m->nr_valid_paths);
1018
1019 schedule_work(&m->trigger_event);
1020
1021 out:
1022 spin_unlock_irqrestore(&m->lock, flags);
1023
1024 return 0;
1025 }
1026
1027 /*
1028 * Reinstate a previously-failed path
1029 */
1030 static int reinstate_path(struct pgpath *pgpath)
1031 {
1032 int r = 0;
1033 unsigned long flags;
1034 struct multipath *m = pgpath->pg->m;
1035
1036 spin_lock_irqsave(&m->lock, flags);
1037
1038 if (pgpath->is_active)
1039 goto out;
1040
1041 if (!pgpath->pg->ps.type->reinstate_path) {
1042 DMWARN("Reinstate path not supported by path selector %s",
1043 pgpath->pg->ps.type->name);
1044 r = -EINVAL;
1045 goto out;
1046 }
1047
1048 r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
1049 if (r)
1050 goto out;
1051
1052 pgpath->is_active = 1;
1053
1054 if (!m->nr_valid_paths++ && m->queue_size) {
1055 m->current_pgpath = NULL;
1056 queue_work(kmultipathd, &m->process_queued_ios);
1057 } else if (m->hw_handler_name && (m->current_pg == pgpath->pg)) {
1058 if (queue_work(kmpath_handlerd, &pgpath->activate_path.work))
1059 m->pg_init_in_progress++;
1060 }
1061
1062 dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti,
1063 pgpath->path.dev->name, m->nr_valid_paths);
1064
1065 schedule_work(&m->trigger_event);
1066
1067 out:
1068 spin_unlock_irqrestore(&m->lock, flags);
1069
1070 return r;
1071 }
1072
1073 /*
1074 * Fail or reinstate all paths that match the provided struct dm_dev.
1075 */
1076 static int action_dev(struct multipath *m, struct dm_dev *dev,
1077 action_fn action)
1078 {
1079 int r = -EINVAL;
1080 struct pgpath *pgpath;
1081 struct priority_group *pg;
1082
1083 list_for_each_entry(pg, &m->priority_groups, list) {
1084 list_for_each_entry(pgpath, &pg->pgpaths, list) {
1085 if (pgpath->path.dev == dev)
1086 r = action(pgpath);
1087 }
1088 }
1089
1090 return r;
1091 }
1092
1093 /*
1094 * Temporarily try to avoid having to use the specified PG
1095 */
1096 static void bypass_pg(struct multipath *m, struct priority_group *pg,
1097 int bypassed)
1098 {
1099 unsigned long flags;
1100
1101 spin_lock_irqsave(&m->lock, flags);
1102
1103 pg->bypassed = bypassed;
1104 m->current_pgpath = NULL;
1105 m->current_pg = NULL;
1106
1107 spin_unlock_irqrestore(&m->lock, flags);
1108
1109 schedule_work(&m->trigger_event);
1110 }
1111
1112 /*
1113 * Switch to using the specified PG from the next I/O that gets mapped
1114 */
1115 static int switch_pg_num(struct multipath *m, const char *pgstr)
1116 {
1117 struct priority_group *pg;
1118 unsigned pgnum;
1119 unsigned long flags;
1120 char dummy;
1121
1122 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1123 (pgnum > m->nr_priority_groups)) {
1124 DMWARN("invalid PG number supplied to switch_pg_num");
1125 return -EINVAL;
1126 }
1127
1128 spin_lock_irqsave(&m->lock, flags);
1129 list_for_each_entry(pg, &m->priority_groups, list) {
1130 pg->bypassed = 0;
1131 if (--pgnum)
1132 continue;
1133
1134 m->current_pgpath = NULL;
1135 m->current_pg = NULL;
1136 m->next_pg = pg;
1137 }
1138 spin_unlock_irqrestore(&m->lock, flags);
1139
1140 schedule_work(&m->trigger_event);
1141 return 0;
1142 }
1143
1144 /*
1145 * Set/clear bypassed status of a PG.
1146 * PGs are numbered upwards from 1 in the order they were declared.
1147 */
1148 static int bypass_pg_num(struct multipath *m, const char *pgstr, int bypassed)
1149 {
1150 struct priority_group *pg;
1151 unsigned pgnum;
1152 char dummy;
1153
1154 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1155 (pgnum > m->nr_priority_groups)) {
1156 DMWARN("invalid PG number supplied to bypass_pg");
1157 return -EINVAL;
1158 }
1159
1160 list_for_each_entry(pg, &m->priority_groups, list) {
1161 if (!--pgnum)
1162 break;
1163 }
1164
1165 bypass_pg(m, pg, bypassed);
1166 return 0;
1167 }
1168
1169 /*
1170 * Should we retry pg_init immediately?
1171 */
1172 static int pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath)
1173 {
1174 unsigned long flags;
1175 int limit_reached = 0;
1176
1177 spin_lock_irqsave(&m->lock, flags);
1178
1179 if (m->pg_init_count <= m->pg_init_retries && !m->pg_init_disabled)
1180 m->pg_init_required = 1;
1181 else
1182 limit_reached = 1;
1183
1184 spin_unlock_irqrestore(&m->lock, flags);
1185
1186 return limit_reached;
1187 }
1188
1189 static void pg_init_done(void *data, int errors)
1190 {
1191 struct pgpath *pgpath = data;
1192 struct priority_group *pg = pgpath->pg;
1193 struct multipath *m = pg->m;
1194 unsigned long flags;
1195 unsigned delay_retry = 0;
1196
1197 /* device or driver problems */
1198 switch (errors) {
1199 case SCSI_DH_OK:
1200 break;
1201 case SCSI_DH_NOSYS:
1202 if (!m->hw_handler_name) {
1203 errors = 0;
1204 break;
1205 }
1206 DMERR("Could not failover the device: Handler scsi_dh_%s "
1207 "Error %d.", m->hw_handler_name, errors);
1208 /*
1209 * Fail path for now, so we do not ping pong
1210 */
1211 fail_path(pgpath);
1212 break;
1213 case SCSI_DH_DEV_TEMP_BUSY:
1214 /*
1215 * Probably doing something like FW upgrade on the
1216 * controller so try the other pg.
1217 */
1218 bypass_pg(m, pg, 1);
1219 break;
1220 case SCSI_DH_RETRY:
1221 /* Wait before retrying. */
1222 delay_retry = 1;
1223 case SCSI_DH_IMM_RETRY:
1224 case SCSI_DH_RES_TEMP_UNAVAIL:
1225 if (pg_init_limit_reached(m, pgpath))
1226 fail_path(pgpath);
1227 errors = 0;
1228 break;
1229 default:
1230 /*
1231 * We probably do not want to fail the path for a device
1232 * error, but this is what the old dm did. In future
1233 * patches we can do more advanced handling.
1234 */
1235 fail_path(pgpath);
1236 }
1237
1238 spin_lock_irqsave(&m->lock, flags);
1239 if (errors) {
1240 if (pgpath == m->current_pgpath) {
1241 DMERR("Could not failover device. Error %d.", errors);
1242 m->current_pgpath = NULL;
1243 m->current_pg = NULL;
1244 }
1245 } else if (!m->pg_init_required)
1246 pg->bypassed = 0;
1247
1248 if (--m->pg_init_in_progress)
1249 /* Activations of other paths are still on going */
1250 goto out;
1251
1252 if (!m->pg_init_required)
1253 m->queue_io = 0;
1254
1255 m->pg_init_delay_retry = delay_retry;
1256 queue_work(kmultipathd, &m->process_queued_ios);
1257
1258 /*
1259 * Wake up any thread waiting to suspend.
1260 */
1261 wake_up(&m->pg_init_wait);
1262
1263 out:
1264 spin_unlock_irqrestore(&m->lock, flags);
1265 }
1266
1267 static void activate_path(struct work_struct *work)
1268 {
1269 struct pgpath *pgpath =
1270 container_of(work, struct pgpath, activate_path.work);
1271
1272 scsi_dh_activate(bdev_get_queue(pgpath->path.dev->bdev),
1273 pg_init_done, pgpath);
1274 }
1275
1276 /*
1277 * end_io handling
1278 */
1279 static int do_end_io(struct multipath *m, struct request *clone,
1280 int error, struct dm_mpath_io *mpio)
1281 {
1282 /*
1283 * We don't queue any clone request inside the multipath target
1284 * during end I/O handling, since those clone requests don't have
1285 * bio clones. If we queue them inside the multipath target,
1286 * we need to make bio clones, that requires memory allocation.
1287 * (See drivers/md/dm.c:end_clone_bio() about why the clone requests
1288 * don't have bio clones.)
1289 * Instead of queueing the clone request here, we queue the original
1290 * request into dm core, which will remake a clone request and
1291 * clone bios for it and resubmit it later.
1292 */
1293 int r = DM_ENDIO_REQUEUE;
1294 unsigned long flags;
1295
1296 if (!error && !clone->errors)
1297 return 0; /* I/O complete */
1298
1299 if (error == -EOPNOTSUPP || error == -EREMOTEIO || error == -EILSEQ) {
1300 if ((clone->cmd_flags & REQ_WRITE_SAME) &&
1301 !clone->q->limits.max_write_same_sectors) {
1302 struct queue_limits *limits;
1303
1304 /* device doesn't really support WRITE SAME, disable it */
1305 limits = dm_get_queue_limits(dm_table_get_md(m->ti->table));
1306 limits->max_write_same_sectors = 0;
1307 }
1308 return error;
1309 }
1310
1311 if (mpio->pgpath)
1312 fail_path(mpio->pgpath);
1313
1314 spin_lock_irqsave(&m->lock, flags);
1315 if (!m->nr_valid_paths) {
1316 if (!m->queue_if_no_path) {
1317 if (!__must_push_back(m))
1318 r = -EIO;
1319 } else {
1320 if (error == -EBADE)
1321 r = error;
1322 }
1323 }
1324 spin_unlock_irqrestore(&m->lock, flags);
1325
1326 return r;
1327 }
1328
1329 static int multipath_end_io(struct dm_target *ti, struct request *clone,
1330 int error, union map_info *map_context)
1331 {
1332 struct multipath *m = ti->private;
1333 struct dm_mpath_io *mpio = map_context->ptr;
1334 struct pgpath *pgpath;
1335 struct path_selector *ps;
1336 int r;
1337
1338 BUG_ON(!mpio);
1339
1340 r = do_end_io(m, clone, error, mpio);
1341 pgpath = mpio->pgpath;
1342 if (pgpath) {
1343 ps = &pgpath->pg->ps;
1344 if (ps->type->end_io)
1345 ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
1346 }
1347 clear_mapinfo(m, map_context);
1348
1349 return r;
1350 }
1351
1352 /*
1353 * Suspend can't complete until all the I/O is processed so if
1354 * the last path fails we must error any remaining I/O.
1355 * Note that if the freeze_bdev fails while suspending, the
1356 * queue_if_no_path state is lost - userspace should reset it.
1357 */
1358 static void multipath_presuspend(struct dm_target *ti)
1359 {
1360 struct multipath *m = (struct multipath *) ti->private;
1361
1362 queue_if_no_path(m, 0, 1);
1363 }
1364
1365 static void multipath_postsuspend(struct dm_target *ti)
1366 {
1367 struct multipath *m = ti->private;
1368
1369 mutex_lock(&m->work_mutex);
1370 flush_multipath_work(m);
1371 mutex_unlock(&m->work_mutex);
1372 }
1373
1374 /*
1375 * Restore the queue_if_no_path setting.
1376 */
1377 static void multipath_resume(struct dm_target *ti)
1378 {
1379 struct multipath *m = (struct multipath *) ti->private;
1380 unsigned long flags;
1381
1382 spin_lock_irqsave(&m->lock, flags);
1383 m->queue_if_no_path = m->saved_queue_if_no_path;
1384 spin_unlock_irqrestore(&m->lock, flags);
1385 }
1386
1387 /*
1388 * Info output has the following format:
1389 * num_multipath_feature_args [multipath_feature_args]*
1390 * num_handler_status_args [handler_status_args]*
1391 * num_groups init_group_number
1392 * [A|D|E num_ps_status_args [ps_status_args]*
1393 * num_paths num_selector_args
1394 * [path_dev A|F fail_count [selector_args]* ]+ ]+
1395 *
1396 * Table output has the following format (identical to the constructor string):
1397 * num_feature_args [features_args]*
1398 * num_handler_args hw_handler [hw_handler_args]*
1399 * num_groups init_group_number
1400 * [priority selector-name num_ps_args [ps_args]*
1401 * num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
1402 */
1403 static void multipath_status(struct dm_target *ti, status_type_t type,
1404 unsigned status_flags, char *result, unsigned maxlen)
1405 {
1406 int sz = 0;
1407 unsigned long flags;
1408 struct multipath *m = (struct multipath *) ti->private;
1409 struct priority_group *pg;
1410 struct pgpath *p;
1411 unsigned pg_num;
1412 char state;
1413
1414 spin_lock_irqsave(&m->lock, flags);
1415
1416 /* Features */
1417 if (type == STATUSTYPE_INFO)
1418 DMEMIT("2 %u %u ", m->queue_size, m->pg_init_count);
1419 else {
1420 DMEMIT("%u ", m->queue_if_no_path +
1421 (m->pg_init_retries > 0) * 2 +
1422 (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT) * 2 +
1423 m->retain_attached_hw_handler);
1424 if (m->queue_if_no_path)
1425 DMEMIT("queue_if_no_path ");
1426 if (m->pg_init_retries)
1427 DMEMIT("pg_init_retries %u ", m->pg_init_retries);
1428 if (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT)
1429 DMEMIT("pg_init_delay_msecs %u ", m->pg_init_delay_msecs);
1430 if (m->retain_attached_hw_handler)
1431 DMEMIT("retain_attached_hw_handler ");
1432 }
1433
1434 if (!m->hw_handler_name || type == STATUSTYPE_INFO)
1435 DMEMIT("0 ");
1436 else
1437 DMEMIT("1 %s ", m->hw_handler_name);
1438
1439 DMEMIT("%u ", m->nr_priority_groups);
1440
1441 if (m->next_pg)
1442 pg_num = m->next_pg->pg_num;
1443 else if (m->current_pg)
1444 pg_num = m->current_pg->pg_num;
1445 else
1446 pg_num = (m->nr_priority_groups ? 1 : 0);
1447
1448 DMEMIT("%u ", pg_num);
1449
1450 switch (type) {
1451 case STATUSTYPE_INFO:
1452 list_for_each_entry(pg, &m->priority_groups, list) {
1453 if (pg->bypassed)
1454 state = 'D'; /* Disabled */
1455 else if (pg == m->current_pg)
1456 state = 'A'; /* Currently Active */
1457 else
1458 state = 'E'; /* Enabled */
1459
1460 DMEMIT("%c ", state);
1461
1462 if (pg->ps.type->status)
1463 sz += pg->ps.type->status(&pg->ps, NULL, type,
1464 result + sz,
1465 maxlen - sz);
1466 else
1467 DMEMIT("0 ");
1468
1469 DMEMIT("%u %u ", pg->nr_pgpaths,
1470 pg->ps.type->info_args);
1471
1472 list_for_each_entry(p, &pg->pgpaths, list) {
1473 DMEMIT("%s %s %u ", p->path.dev->name,
1474 p->is_active ? "A" : "F",
1475 p->fail_count);
1476 if (pg->ps.type->status)
1477 sz += pg->ps.type->status(&pg->ps,
1478 &p->path, type, result + sz,
1479 maxlen - sz);
1480 }
1481 }
1482 break;
1483
1484 case STATUSTYPE_TABLE:
1485 list_for_each_entry(pg, &m->priority_groups, list) {
1486 DMEMIT("%s ", pg->ps.type->name);
1487
1488 if (pg->ps.type->status)
1489 sz += pg->ps.type->status(&pg->ps, NULL, type,
1490 result + sz,
1491 maxlen - sz);
1492 else
1493 DMEMIT("0 ");
1494
1495 DMEMIT("%u %u ", pg->nr_pgpaths,
1496 pg->ps.type->table_args);
1497
1498 list_for_each_entry(p, &pg->pgpaths, list) {
1499 DMEMIT("%s ", p->path.dev->name);
1500 if (pg->ps.type->status)
1501 sz += pg->ps.type->status(&pg->ps,
1502 &p->path, type, result + sz,
1503 maxlen - sz);
1504 }
1505 }
1506 break;
1507 }
1508
1509 spin_unlock_irqrestore(&m->lock, flags);
1510 }
1511
1512 static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
1513 {
1514 int r = -EINVAL;
1515 struct dm_dev *dev;
1516 struct multipath *m = (struct multipath *) ti->private;
1517 action_fn action;
1518
1519 mutex_lock(&m->work_mutex);
1520
1521 if (dm_suspended(ti)) {
1522 r = -EBUSY;
1523 goto out;
1524 }
1525
1526 if (argc == 1) {
1527 if (!strcasecmp(argv[0], "queue_if_no_path")) {
1528 r = queue_if_no_path(m, 1, 0);
1529 goto out;
1530 } else if (!strcasecmp(argv[0], "fail_if_no_path")) {
1531 r = queue_if_no_path(m, 0, 0);
1532 goto out;
1533 }
1534 }
1535
1536 if (argc != 2) {
1537 DMWARN("Unrecognised multipath message received.");
1538 goto out;
1539 }
1540
1541 if (!strcasecmp(argv[0], "disable_group")) {
1542 r = bypass_pg_num(m, argv[1], 1);
1543 goto out;
1544 } else if (!strcasecmp(argv[0], "enable_group")) {
1545 r = bypass_pg_num(m, argv[1], 0);
1546 goto out;
1547 } else if (!strcasecmp(argv[0], "switch_group")) {
1548 r = switch_pg_num(m, argv[1]);
1549 goto out;
1550 } else if (!strcasecmp(argv[0], "reinstate_path"))
1551 action = reinstate_path;
1552 else if (!strcasecmp(argv[0], "fail_path"))
1553 action = fail_path;
1554 else {
1555 DMWARN("Unrecognised multipath message received.");
1556 goto out;
1557 }
1558
1559 r = dm_get_device(ti, argv[1], dm_table_get_mode(ti->table), &dev);
1560 if (r) {
1561 DMWARN("message: error getting device %s",
1562 argv[1]);
1563 goto out;
1564 }
1565
1566 r = action_dev(m, dev, action);
1567
1568 dm_put_device(ti, dev);
1569
1570 out:
1571 mutex_unlock(&m->work_mutex);
1572 return r;
1573 }
1574
1575 static int multipath_ioctl(struct dm_target *ti, unsigned int cmd,
1576 unsigned long arg)
1577 {
1578 struct multipath *m = ti->private;
1579 struct pgpath *pgpath;
1580 struct block_device *bdev;
1581 fmode_t mode;
1582 unsigned long flags;
1583 int r;
1584
1585 bdev = NULL;
1586 mode = 0;
1587 r = 0;
1588
1589 spin_lock_irqsave(&m->lock, flags);
1590
1591 if (!m->current_pgpath)
1592 __choose_pgpath(m, 0);
1593
1594 pgpath = m->current_pgpath;
1595
1596 if (pgpath) {
1597 bdev = pgpath->path.dev->bdev;
1598 mode = pgpath->path.dev->mode;
1599 }
1600
1601 if ((pgpath && m->queue_io) || (!pgpath && m->queue_if_no_path))
1602 r = -ENOTCONN;
1603 else if (!bdev)
1604 r = -EIO;
1605
1606 spin_unlock_irqrestore(&m->lock, flags);
1607
1608 /*
1609 * Only pass ioctls through if the device sizes match exactly.
1610 */
1611 if (!r && ti->len != i_size_read(bdev->bd_inode) >> SECTOR_SHIFT)
1612 r = scsi_verify_blk_ioctl(NULL, cmd);
1613
1614 if (r == -ENOTCONN && !fatal_signal_pending(current))
1615 queue_work(kmultipathd, &m->process_queued_ios);
1616
1617 return r ? : __blkdev_driver_ioctl(bdev, mode, cmd, arg);
1618 }
1619
1620 static int multipath_iterate_devices(struct dm_target *ti,
1621 iterate_devices_callout_fn fn, void *data)
1622 {
1623 struct multipath *m = ti->private;
1624 struct priority_group *pg;
1625 struct pgpath *p;
1626 int ret = 0;
1627
1628 list_for_each_entry(pg, &m->priority_groups, list) {
1629 list_for_each_entry(p, &pg->pgpaths, list) {
1630 ret = fn(ti, p->path.dev, ti->begin, ti->len, data);
1631 if (ret)
1632 goto out;
1633 }
1634 }
1635
1636 out:
1637 return ret;
1638 }
1639
1640 static int __pgpath_busy(struct pgpath *pgpath)
1641 {
1642 struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
1643
1644 return dm_underlying_device_busy(q);
1645 }
1646
1647 /*
1648 * We return "busy", only when we can map I/Os but underlying devices
1649 * are busy (so even if we map I/Os now, the I/Os will wait on
1650 * the underlying queue).
1651 * In other words, if we want to kill I/Os or queue them inside us
1652 * due to map unavailability, we don't return "busy". Otherwise,
1653 * dm core won't give us the I/Os and we can't do what we want.
1654 */
1655 static int multipath_busy(struct dm_target *ti)
1656 {
1657 int busy = 0, has_active = 0;
1658 struct multipath *m = ti->private;
1659 struct priority_group *pg;
1660 struct pgpath *pgpath;
1661 unsigned long flags;
1662
1663 spin_lock_irqsave(&m->lock, flags);
1664
1665 /* Guess which priority_group will be used at next mapping time */
1666 if (unlikely(!m->current_pgpath && m->next_pg))
1667 pg = m->next_pg;
1668 else if (likely(m->current_pg))
1669 pg = m->current_pg;
1670 else
1671 /*
1672 * We don't know which pg will be used at next mapping time.
1673 * We don't call __choose_pgpath() here to avoid to trigger
1674 * pg_init just by busy checking.
1675 * So we don't know whether underlying devices we will be using
1676 * at next mapping time are busy or not. Just try mapping.
1677 */
1678 goto out;
1679
1680 /*
1681 * If there is one non-busy active path at least, the path selector
1682 * will be able to select it. So we consider such a pg as not busy.
1683 */
1684 busy = 1;
1685 list_for_each_entry(pgpath, &pg->pgpaths, list)
1686 if (pgpath->is_active) {
1687 has_active = 1;
1688
1689 if (!__pgpath_busy(pgpath)) {
1690 busy = 0;
1691 break;
1692 }
1693 }
1694
1695 if (!has_active)
1696 /*
1697 * No active path in this pg, so this pg won't be used and
1698 * the current_pg will be changed at next mapping time.
1699 * We need to try mapping to determine it.
1700 */
1701 busy = 0;
1702
1703 out:
1704 spin_unlock_irqrestore(&m->lock, flags);
1705
1706 return busy;
1707 }
1708
1709 /*-----------------------------------------------------------------
1710 * Module setup
1711 *---------------------------------------------------------------*/
1712 static struct target_type multipath_target = {
1713 .name = "multipath",
1714 .version = {1, 6, 0},
1715 .module = THIS_MODULE,
1716 .ctr = multipath_ctr,
1717 .dtr = multipath_dtr,
1718 .map_rq = multipath_map,
1719 .rq_end_io = multipath_end_io,
1720 .presuspend = multipath_presuspend,
1721 .postsuspend = multipath_postsuspend,
1722 .resume = multipath_resume,
1723 .status = multipath_status,
1724 .message = multipath_message,
1725 .ioctl = multipath_ioctl,
1726 .iterate_devices = multipath_iterate_devices,
1727 .busy = multipath_busy,
1728 };
1729
1730 static int __init dm_multipath_init(void)
1731 {
1732 int r;
1733
1734 /* allocate a slab for the dm_ios */
1735 _mpio_cache = KMEM_CACHE(dm_mpath_io, 0);
1736 if (!_mpio_cache)
1737 return -ENOMEM;
1738
1739 r = dm_register_target(&multipath_target);
1740 if (r < 0) {
1741 DMERR("register failed %d", r);
1742 kmem_cache_destroy(_mpio_cache);
1743 return -EINVAL;
1744 }
1745
1746 kmultipathd = alloc_workqueue("kmpathd", WQ_MEM_RECLAIM, 0);
1747 if (!kmultipathd) {
1748 DMERR("failed to create workqueue kmpathd");
1749 dm_unregister_target(&multipath_target);
1750 kmem_cache_destroy(_mpio_cache);
1751 return -ENOMEM;
1752 }
1753
1754 /*
1755 * A separate workqueue is used to handle the device handlers
1756 * to avoid overloading existing workqueue. Overloading the
1757 * old workqueue would also create a bottleneck in the
1758 * path of the storage hardware device activation.
1759 */
1760 kmpath_handlerd = alloc_ordered_workqueue("kmpath_handlerd",
1761 WQ_MEM_RECLAIM);
1762 if (!kmpath_handlerd) {
1763 DMERR("failed to create workqueue kmpath_handlerd");
1764 destroy_workqueue(kmultipathd);
1765 dm_unregister_target(&multipath_target);
1766 kmem_cache_destroy(_mpio_cache);
1767 return -ENOMEM;
1768 }
1769
1770 DMINFO("version %u.%u.%u loaded",
1771 multipath_target.version[0], multipath_target.version[1],
1772 multipath_target.version[2]);
1773
1774 return r;
1775 }
1776
1777 static void __exit dm_multipath_exit(void)
1778 {
1779 destroy_workqueue(kmpath_handlerd);
1780 destroy_workqueue(kmultipathd);
1781
1782 dm_unregister_target(&multipath_target);
1783 kmem_cache_destroy(_mpio_cache);
1784 }
1785
1786 module_init(dm_multipath_init);
1787 module_exit(dm_multipath_exit);
1788
1789 MODULE_DESCRIPTION(DM_NAME " multipath target");
1790 MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
1791 MODULE_LICENSE("GPL");
kernel source for telekom puls (alcatel/mediatek)