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scsi: ultrastor.c depends on ISA_DMA_API
[deliverable/linux.git] / drivers / md / dm-mpath.c
1 /*
2 * Copyright (C) 2003 Sistina Software Limited.
3 * Copyright (C) 2004-2005 Red Hat, Inc. All rights reserved.
4 *
5 * This file is released under the GPL.
6 */
7
8 #include <linux/device-mapper.h>
9
10 #include "dm.h"
11 #include "dm-path-selector.h"
12 #include "dm-uevent.h"
13
14 #include <linux/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 #include <linux/blk-mq.h>
27
28 #define DM_MSG_PREFIX "multipath"
29 #define DM_PG_INIT_DELAY_MSECS 2000
30 #define DM_PG_INIT_DELAY_DEFAULT ((unsigned) -1)
31
32 /* Path properties */
33 struct pgpath {
34 struct list_head list;
35
36 struct priority_group *pg; /* Owning PG */
37 unsigned fail_count; /* Cumulative failure count */
38
39 struct dm_path path;
40 struct delayed_work activate_path;
41
42 bool is_active:1; /* Path status */
43 };
44
45 #define path_to_pgpath(__pgp) container_of((__pgp), struct pgpath, path)
46
47 /*
48 * Paths are grouped into Priority Groups and numbered from 1 upwards.
49 * Each has a path selector which controls which path gets used.
50 */
51 struct priority_group {
52 struct list_head list;
53
54 struct multipath *m; /* Owning multipath instance */
55 struct path_selector ps;
56
57 unsigned pg_num; /* Reference number */
58 unsigned nr_pgpaths; /* Number of paths in PG */
59 struct list_head pgpaths;
60
61 bool bypassed:1; /* Temporarily bypass this PG? */
62 };
63
64 /* Multipath context */
65 struct multipath {
66 struct list_head list;
67 struct dm_target *ti;
68
69 const char *hw_handler_name;
70 char *hw_handler_params;
71
72 spinlock_t lock;
73
74 unsigned nr_priority_groups;
75 struct list_head priority_groups;
76
77 wait_queue_head_t pg_init_wait; /* Wait for pg_init completion */
78
79 struct pgpath *current_pgpath;
80 struct priority_group *current_pg;
81 struct priority_group *next_pg; /* Switch to this PG if set */
82
83 unsigned long flags; /* Multipath state flags */
84
85 unsigned pg_init_retries; /* Number of times to retry pg_init */
86 unsigned pg_init_delay_msecs; /* Number of msecs before pg_init retry */
87
88 atomic_t nr_valid_paths; /* Total number of usable paths */
89 atomic_t pg_init_in_progress; /* Only one pg_init allowed at once */
90 atomic_t pg_init_count; /* Number of times pg_init called */
91
92 /*
93 * We must use a mempool of dm_mpath_io structs so that we
94 * can resubmit bios on error.
95 */
96 mempool_t *mpio_pool;
97
98 struct mutex work_mutex;
99 struct work_struct trigger_event;
100 };
101
102 /*
103 * Context information attached to each bio we process.
104 */
105 struct dm_mpath_io {
106 struct pgpath *pgpath;
107 size_t nr_bytes;
108 };
109
110 typedef int (*action_fn) (struct pgpath *pgpath);
111
112 static struct kmem_cache *_mpio_cache;
113
114 static struct workqueue_struct *kmultipathd, *kmpath_handlerd;
115 static void trigger_event(struct work_struct *work);
116 static void activate_path(struct work_struct *work);
117
118 /*-----------------------------------------------
119 * Multipath state flags.
120 *-----------------------------------------------*/
121
122 #define MPATHF_QUEUE_IO 0 /* Must we queue all I/O? */
123 #define MPATHF_QUEUE_IF_NO_PATH 1 /* Queue I/O if last path fails? */
124 #define MPATHF_SAVED_QUEUE_IF_NO_PATH 2 /* Saved state during suspension */
125 #define MPATHF_RETAIN_ATTACHED_HW_HANDLER 3 /* If there's already a hw_handler present, don't change it. */
126 #define MPATHF_PG_INIT_DISABLED 4 /* pg_init is not currently allowed */
127 #define MPATHF_PG_INIT_REQUIRED 5 /* pg_init needs calling? */
128 #define MPATHF_PG_INIT_DELAY_RETRY 6 /* Delay pg_init retry? */
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 = true;
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
167 list_for_each_entry_safe(pgpath, tmp, pgpaths, list) {
168 list_del(&pgpath->list);
169 dm_put_device(ti, pgpath->path.dev);
170 free_pgpath(pgpath);
171 }
172 }
173
174 static void free_priority_group(struct priority_group *pg,
175 struct dm_target *ti)
176 {
177 struct path_selector *ps = &pg->ps;
178
179 if (ps->type) {
180 ps->type->destroy(ps);
181 dm_put_path_selector(ps->type);
182 }
183
184 free_pgpaths(&pg->pgpaths, ti);
185 kfree(pg);
186 }
187
188 static struct multipath *alloc_multipath(struct dm_target *ti, bool use_blk_mq)
189 {
190 struct multipath *m;
191
192 m = kzalloc(sizeof(*m), GFP_KERNEL);
193 if (m) {
194 INIT_LIST_HEAD(&m->priority_groups);
195 spin_lock_init(&m->lock);
196 set_bit(MPATHF_QUEUE_IO, &m->flags);
197 atomic_set(&m->nr_valid_paths, 0);
198 atomic_set(&m->pg_init_in_progress, 0);
199 atomic_set(&m->pg_init_count, 0);
200 m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT;
201 INIT_WORK(&m->trigger_event, trigger_event);
202 init_waitqueue_head(&m->pg_init_wait);
203 mutex_init(&m->work_mutex);
204
205 m->mpio_pool = NULL;
206 if (!use_blk_mq) {
207 unsigned min_ios = dm_get_reserved_rq_based_ios();
208
209 m->mpio_pool = mempool_create_slab_pool(min_ios, _mpio_cache);
210 if (!m->mpio_pool) {
211 kfree(m);
212 return NULL;
213 }
214 }
215
216 m->ti = ti;
217 ti->private = m;
218 }
219
220 return m;
221 }
222
223 static void free_multipath(struct multipath *m)
224 {
225 struct priority_group *pg, *tmp;
226
227 list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) {
228 list_del(&pg->list);
229 free_priority_group(pg, m->ti);
230 }
231
232 kfree(m->hw_handler_name);
233 kfree(m->hw_handler_params);
234 mempool_destroy(m->mpio_pool);
235 kfree(m);
236 }
237
238 static struct dm_mpath_io *get_mpio(union map_info *info)
239 {
240 return info->ptr;
241 }
242
243 static struct dm_mpath_io *set_mpio(struct multipath *m, union map_info *info)
244 {
245 struct dm_mpath_io *mpio;
246
247 if (!m->mpio_pool) {
248 /* Use blk-mq pdu memory requested via per_io_data_size */
249 mpio = get_mpio(info);
250 memset(mpio, 0, sizeof(*mpio));
251 return mpio;
252 }
253
254 mpio = mempool_alloc(m->mpio_pool, GFP_ATOMIC);
255 if (!mpio)
256 return NULL;
257
258 memset(mpio, 0, sizeof(*mpio));
259 info->ptr = mpio;
260
261 return mpio;
262 }
263
264 static void clear_request_fn_mpio(struct multipath *m, union map_info *info)
265 {
266 /* Only needed for non blk-mq (.request_fn) multipath */
267 if (m->mpio_pool) {
268 struct dm_mpath_io *mpio = info->ptr;
269
270 info->ptr = NULL;
271 mempool_free(mpio, m->mpio_pool);
272 }
273 }
274
275 /*-----------------------------------------------
276 * Path selection
277 *-----------------------------------------------*/
278
279 static int __pg_init_all_paths(struct multipath *m)
280 {
281 struct pgpath *pgpath;
282 unsigned long pg_init_delay = 0;
283
284 if (atomic_read(&m->pg_init_in_progress) || test_bit(MPATHF_PG_INIT_DISABLED, &m->flags))
285 return 0;
286
287 atomic_inc(&m->pg_init_count);
288 clear_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
289
290 /* Check here to reset pg_init_required */
291 if (!m->current_pg)
292 return 0;
293
294 if (test_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags))
295 pg_init_delay = msecs_to_jiffies(m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT ?
296 m->pg_init_delay_msecs : DM_PG_INIT_DELAY_MSECS);
297 list_for_each_entry(pgpath, &m->current_pg->pgpaths, list) {
298 /* Skip failed paths */
299 if (!pgpath->is_active)
300 continue;
301 if (queue_delayed_work(kmpath_handlerd, &pgpath->activate_path,
302 pg_init_delay))
303 atomic_inc(&m->pg_init_in_progress);
304 }
305 return atomic_read(&m->pg_init_in_progress);
306 }
307
308 static int pg_init_all_paths(struct multipath *m)
309 {
310 int r;
311 unsigned long flags;
312
313 spin_lock_irqsave(&m->lock, flags);
314 r = __pg_init_all_paths(m);
315 spin_unlock_irqrestore(&m->lock, flags);
316
317 return r;
318 }
319
320 static void __switch_pg(struct multipath *m, struct priority_group *pg)
321 {
322 m->current_pg = pg;
323
324 /* Must we initialise the PG first, and queue I/O till it's ready? */
325 if (m->hw_handler_name) {
326 set_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
327 set_bit(MPATHF_QUEUE_IO, &m->flags);
328 } else {
329 clear_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
330 clear_bit(MPATHF_QUEUE_IO, &m->flags);
331 }
332
333 atomic_set(&m->pg_init_count, 0);
334 }
335
336 static struct pgpath *choose_path_in_pg(struct multipath *m,
337 struct priority_group *pg,
338 size_t nr_bytes)
339 {
340 unsigned long flags;
341 struct dm_path *path;
342 struct pgpath *pgpath;
343
344 path = pg->ps.type->select_path(&pg->ps, nr_bytes);
345 if (!path)
346 return ERR_PTR(-ENXIO);
347
348 pgpath = path_to_pgpath(path);
349
350 if (unlikely(lockless_dereference(m->current_pg) != pg)) {
351 /* Only update current_pgpath if pg changed */
352 spin_lock_irqsave(&m->lock, flags);
353 m->current_pgpath = pgpath;
354 __switch_pg(m, pg);
355 spin_unlock_irqrestore(&m->lock, flags);
356 }
357
358 return pgpath;
359 }
360
361 static struct pgpath *choose_pgpath(struct multipath *m, size_t nr_bytes)
362 {
363 unsigned long flags;
364 struct priority_group *pg;
365 struct pgpath *pgpath;
366 bool bypassed = true;
367
368 if (!atomic_read(&m->nr_valid_paths)) {
369 clear_bit(MPATHF_QUEUE_IO, &m->flags);
370 goto failed;
371 }
372
373 /* Were we instructed to switch PG? */
374 if (lockless_dereference(m->next_pg)) {
375 spin_lock_irqsave(&m->lock, flags);
376 pg = m->next_pg;
377 if (!pg) {
378 spin_unlock_irqrestore(&m->lock, flags);
379 goto check_current_pg;
380 }
381 m->next_pg = NULL;
382 spin_unlock_irqrestore(&m->lock, flags);
383 pgpath = choose_path_in_pg(m, pg, nr_bytes);
384 if (!IS_ERR_OR_NULL(pgpath))
385 return pgpath;
386 }
387
388 /* Don't change PG until it has no remaining paths */
389 check_current_pg:
390 pg = lockless_dereference(m->current_pg);
391 if (pg) {
392 pgpath = choose_path_in_pg(m, pg, nr_bytes);
393 if (!IS_ERR_OR_NULL(pgpath))
394 return pgpath;
395 }
396
397 /*
398 * Loop through priority groups until we find a valid path.
399 * First time we skip PGs marked 'bypassed'.
400 * Second time we only try the ones we skipped, but set
401 * pg_init_delay_retry so we do not hammer controllers.
402 */
403 do {
404 list_for_each_entry(pg, &m->priority_groups, list) {
405 if (pg->bypassed == bypassed)
406 continue;
407 pgpath = choose_path_in_pg(m, pg, nr_bytes);
408 if (!IS_ERR_OR_NULL(pgpath)) {
409 if (!bypassed)
410 set_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
411 return pgpath;
412 }
413 }
414 } while (bypassed--);
415
416 failed:
417 spin_lock_irqsave(&m->lock, flags);
418 m->current_pgpath = NULL;
419 m->current_pg = NULL;
420 spin_unlock_irqrestore(&m->lock, flags);
421
422 return NULL;
423 }
424
425 /*
426 * Check whether bios must be queued in the device-mapper core rather
427 * than here in the target.
428 *
429 * If m->queue_if_no_path and m->saved_queue_if_no_path hold the
430 * same value then we are not between multipath_presuspend()
431 * and multipath_resume() calls and we have no need to check
432 * for the DMF_NOFLUSH_SUSPENDING flag.
433 */
434 static int must_push_back(struct multipath *m)
435 {
436 return (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) ||
437 ((test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) !=
438 test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags)) &&
439 dm_noflush_suspending(m->ti)));
440 }
441
442 /*
443 * Map cloned requests
444 */
445 static int __multipath_map(struct dm_target *ti, struct request *clone,
446 union map_info *map_context,
447 struct request *rq, struct request **__clone)
448 {
449 struct multipath *m = ti->private;
450 int r = DM_MAPIO_REQUEUE;
451 size_t nr_bytes = clone ? blk_rq_bytes(clone) : blk_rq_bytes(rq);
452 struct pgpath *pgpath;
453 struct block_device *bdev;
454 struct dm_mpath_io *mpio;
455
456 /* Do we need to select a new pgpath? */
457 pgpath = lockless_dereference(m->current_pgpath);
458 if (!pgpath || !test_bit(MPATHF_QUEUE_IO, &m->flags))
459 pgpath = choose_pgpath(m, nr_bytes);
460
461 if (!pgpath) {
462 if (!must_push_back(m))
463 r = -EIO; /* Failed */
464 return r;
465 } else if (test_bit(MPATHF_QUEUE_IO, &m->flags) ||
466 test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags)) {
467 pg_init_all_paths(m);
468 return r;
469 }
470
471 mpio = set_mpio(m, map_context);
472 if (!mpio)
473 /* ENOMEM, requeue */
474 return r;
475
476 mpio->pgpath = pgpath;
477 mpio->nr_bytes = nr_bytes;
478
479 bdev = pgpath->path.dev->bdev;
480
481 if (clone) {
482 /*
483 * Old request-based interface: allocated clone is passed in.
484 * Used by: .request_fn stacked on .request_fn path(s).
485 */
486 clone->q = bdev_get_queue(bdev);
487 clone->rq_disk = bdev->bd_disk;
488 clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
489 } else {
490 /*
491 * blk-mq request-based interface; used by both:
492 * .request_fn stacked on blk-mq path(s) and
493 * blk-mq stacked on blk-mq path(s).
494 */
495 *__clone = blk_mq_alloc_request(bdev_get_queue(bdev),
496 rq_data_dir(rq), BLK_MQ_REQ_NOWAIT);
497 if (IS_ERR(*__clone)) {
498 /* ENOMEM, requeue */
499 clear_request_fn_mpio(m, map_context);
500 return r;
501 }
502 (*__clone)->bio = (*__clone)->biotail = NULL;
503 (*__clone)->rq_disk = bdev->bd_disk;
504 (*__clone)->cmd_flags |= REQ_FAILFAST_TRANSPORT;
505 }
506
507 if (pgpath->pg->ps.type->start_io)
508 pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
509 &pgpath->path,
510 nr_bytes);
511 return DM_MAPIO_REMAPPED;
512 }
513
514 static int multipath_map(struct dm_target *ti, struct request *clone,
515 union map_info *map_context)
516 {
517 return __multipath_map(ti, clone, map_context, NULL, NULL);
518 }
519
520 static int multipath_clone_and_map(struct dm_target *ti, struct request *rq,
521 union map_info *map_context,
522 struct request **clone)
523 {
524 return __multipath_map(ti, NULL, map_context, rq, clone);
525 }
526
527 static void multipath_release_clone(struct request *clone)
528 {
529 blk_mq_free_request(clone);
530 }
531
532 /*
533 * If we run out of usable paths, should we queue I/O or error it?
534 */
535 static int queue_if_no_path(struct multipath *m, bool queue_if_no_path,
536 bool save_old_value)
537 {
538 unsigned long flags;
539
540 spin_lock_irqsave(&m->lock, flags);
541
542 if (save_old_value) {
543 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
544 set_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
545 else
546 clear_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
547 } else {
548 if (queue_if_no_path)
549 set_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
550 else
551 clear_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
552 }
553 if (queue_if_no_path)
554 set_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
555 else
556 clear_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
557
558 spin_unlock_irqrestore(&m->lock, flags);
559
560 if (!queue_if_no_path)
561 dm_table_run_md_queue_async(m->ti->table);
562
563 return 0;
564 }
565
566 /*
567 * An event is triggered whenever a path is taken out of use.
568 * Includes path failure and PG bypass.
569 */
570 static void trigger_event(struct work_struct *work)
571 {
572 struct multipath *m =
573 container_of(work, struct multipath, trigger_event);
574
575 dm_table_event(m->ti->table);
576 }
577
578 /*-----------------------------------------------------------------
579 * Constructor/argument parsing:
580 * <#multipath feature args> [<arg>]*
581 * <#hw_handler args> [hw_handler [<arg>]*]
582 * <#priority groups>
583 * <initial priority group>
584 * [<selector> <#selector args> [<arg>]*
585 * <#paths> <#per-path selector args>
586 * [<path> [<arg>]* ]+ ]+
587 *---------------------------------------------------------------*/
588 static int parse_path_selector(struct dm_arg_set *as, struct priority_group *pg,
589 struct dm_target *ti)
590 {
591 int r;
592 struct path_selector_type *pst;
593 unsigned ps_argc;
594
595 static struct dm_arg _args[] = {
596 {0, 1024, "invalid number of path selector args"},
597 };
598
599 pst = dm_get_path_selector(dm_shift_arg(as));
600 if (!pst) {
601 ti->error = "unknown path selector type";
602 return -EINVAL;
603 }
604
605 r = dm_read_arg_group(_args, as, &ps_argc, &ti->error);
606 if (r) {
607 dm_put_path_selector(pst);
608 return -EINVAL;
609 }
610
611 r = pst->create(&pg->ps, ps_argc, as->argv);
612 if (r) {
613 dm_put_path_selector(pst);
614 ti->error = "path selector constructor failed";
615 return r;
616 }
617
618 pg->ps.type = pst;
619 dm_consume_args(as, ps_argc);
620
621 return 0;
622 }
623
624 static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps,
625 struct dm_target *ti)
626 {
627 int r;
628 struct pgpath *p;
629 struct multipath *m = ti->private;
630 struct request_queue *q = NULL;
631 const char *attached_handler_name;
632
633 /* we need at least a path arg */
634 if (as->argc < 1) {
635 ti->error = "no device given";
636 return ERR_PTR(-EINVAL);
637 }
638
639 p = alloc_pgpath();
640 if (!p)
641 return ERR_PTR(-ENOMEM);
642
643 r = dm_get_device(ti, dm_shift_arg(as), dm_table_get_mode(ti->table),
644 &p->path.dev);
645 if (r) {
646 ti->error = "error getting device";
647 goto bad;
648 }
649
650 if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags) || m->hw_handler_name)
651 q = bdev_get_queue(p->path.dev->bdev);
652
653 if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags)) {
654 retain:
655 attached_handler_name = scsi_dh_attached_handler_name(q, GFP_KERNEL);
656 if (attached_handler_name) {
657 /*
658 * Reset hw_handler_name to match the attached handler
659 * and clear any hw_handler_params associated with the
660 * ignored handler.
661 *
662 * NB. This modifies the table line to show the actual
663 * handler instead of the original table passed in.
664 */
665 kfree(m->hw_handler_name);
666 m->hw_handler_name = attached_handler_name;
667
668 kfree(m->hw_handler_params);
669 m->hw_handler_params = NULL;
670 }
671 }
672
673 if (m->hw_handler_name) {
674 r = scsi_dh_attach(q, m->hw_handler_name);
675 if (r == -EBUSY) {
676 char b[BDEVNAME_SIZE];
677
678 printk(KERN_INFO "dm-mpath: retaining handler on device %s\n",
679 bdevname(p->path.dev->bdev, b));
680 goto retain;
681 }
682 if (r < 0) {
683 ti->error = "error attaching hardware handler";
684 dm_put_device(ti, p->path.dev);
685 goto bad;
686 }
687
688 if (m->hw_handler_params) {
689 r = scsi_dh_set_params(q, m->hw_handler_params);
690 if (r < 0) {
691 ti->error = "unable to set hardware "
692 "handler parameters";
693 dm_put_device(ti, p->path.dev);
694 goto bad;
695 }
696 }
697 }
698
699 r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
700 if (r) {
701 dm_put_device(ti, p->path.dev);
702 goto bad;
703 }
704
705 return p;
706
707 bad:
708 free_pgpath(p);
709 return ERR_PTR(r);
710 }
711
712 static struct priority_group *parse_priority_group(struct dm_arg_set *as,
713 struct multipath *m)
714 {
715 static struct dm_arg _args[] = {
716 {1, 1024, "invalid number of paths"},
717 {0, 1024, "invalid number of selector args"}
718 };
719
720 int r;
721 unsigned i, nr_selector_args, nr_args;
722 struct priority_group *pg;
723 struct dm_target *ti = m->ti;
724
725 if (as->argc < 2) {
726 as->argc = 0;
727 ti->error = "not enough priority group arguments";
728 return ERR_PTR(-EINVAL);
729 }
730
731 pg = alloc_priority_group();
732 if (!pg) {
733 ti->error = "couldn't allocate priority group";
734 return ERR_PTR(-ENOMEM);
735 }
736 pg->m = m;
737
738 r = parse_path_selector(as, pg, ti);
739 if (r)
740 goto bad;
741
742 /*
743 * read the paths
744 */
745 r = dm_read_arg(_args, as, &pg->nr_pgpaths, &ti->error);
746 if (r)
747 goto bad;
748
749 r = dm_read_arg(_args + 1, as, &nr_selector_args, &ti->error);
750 if (r)
751 goto bad;
752
753 nr_args = 1 + nr_selector_args;
754 for (i = 0; i < pg->nr_pgpaths; i++) {
755 struct pgpath *pgpath;
756 struct dm_arg_set path_args;
757
758 if (as->argc < nr_args) {
759 ti->error = "not enough path parameters";
760 r = -EINVAL;
761 goto bad;
762 }
763
764 path_args.argc = nr_args;
765 path_args.argv = as->argv;
766
767 pgpath = parse_path(&path_args, &pg->ps, ti);
768 if (IS_ERR(pgpath)) {
769 r = PTR_ERR(pgpath);
770 goto bad;
771 }
772
773 pgpath->pg = pg;
774 list_add_tail(&pgpath->list, &pg->pgpaths);
775 dm_consume_args(as, nr_args);
776 }
777
778 return pg;
779
780 bad:
781 free_priority_group(pg, ti);
782 return ERR_PTR(r);
783 }
784
785 static int parse_hw_handler(struct dm_arg_set *as, struct multipath *m)
786 {
787 unsigned hw_argc;
788 int ret;
789 struct dm_target *ti = m->ti;
790
791 static struct dm_arg _args[] = {
792 {0, 1024, "invalid number of hardware handler args"},
793 };
794
795 if (dm_read_arg_group(_args, as, &hw_argc, &ti->error))
796 return -EINVAL;
797
798 if (!hw_argc)
799 return 0;
800
801 m->hw_handler_name = kstrdup(dm_shift_arg(as), GFP_KERNEL);
802
803 if (hw_argc > 1) {
804 char *p;
805 int i, j, len = 4;
806
807 for (i = 0; i <= hw_argc - 2; i++)
808 len += strlen(as->argv[i]) + 1;
809 p = m->hw_handler_params = kzalloc(len, GFP_KERNEL);
810 if (!p) {
811 ti->error = "memory allocation failed";
812 ret = -ENOMEM;
813 goto fail;
814 }
815 j = sprintf(p, "%d", hw_argc - 1);
816 for (i = 0, p+=j+1; i <= hw_argc - 2; i++, p+=j+1)
817 j = sprintf(p, "%s", as->argv[i]);
818 }
819 dm_consume_args(as, hw_argc - 1);
820
821 return 0;
822 fail:
823 kfree(m->hw_handler_name);
824 m->hw_handler_name = NULL;
825 return ret;
826 }
827
828 static int parse_features(struct dm_arg_set *as, struct multipath *m)
829 {
830 int r;
831 unsigned argc;
832 struct dm_target *ti = m->ti;
833 const char *arg_name;
834
835 static struct dm_arg _args[] = {
836 {0, 6, "invalid number of feature args"},
837 {1, 50, "pg_init_retries must be between 1 and 50"},
838 {0, 60000, "pg_init_delay_msecs must be between 0 and 60000"},
839 };
840
841 r = dm_read_arg_group(_args, as, &argc, &ti->error);
842 if (r)
843 return -EINVAL;
844
845 if (!argc)
846 return 0;
847
848 do {
849 arg_name = dm_shift_arg(as);
850 argc--;
851
852 if (!strcasecmp(arg_name, "queue_if_no_path")) {
853 r = queue_if_no_path(m, true, false);
854 continue;
855 }
856
857 if (!strcasecmp(arg_name, "retain_attached_hw_handler")) {
858 set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags);
859 continue;
860 }
861
862 if (!strcasecmp(arg_name, "pg_init_retries") &&
863 (argc >= 1)) {
864 r = dm_read_arg(_args + 1, as, &m->pg_init_retries, &ti->error);
865 argc--;
866 continue;
867 }
868
869 if (!strcasecmp(arg_name, "pg_init_delay_msecs") &&
870 (argc >= 1)) {
871 r = dm_read_arg(_args + 2, as, &m->pg_init_delay_msecs, &ti->error);
872 argc--;
873 continue;
874 }
875
876 ti->error = "Unrecognised multipath feature request";
877 r = -EINVAL;
878 } while (argc && !r);
879
880 return r;
881 }
882
883 static int multipath_ctr(struct dm_target *ti, unsigned int argc,
884 char **argv)
885 {
886 /* target arguments */
887 static struct dm_arg _args[] = {
888 {0, 1024, "invalid number of priority groups"},
889 {0, 1024, "invalid initial priority group number"},
890 };
891
892 int r;
893 struct multipath *m;
894 struct dm_arg_set as;
895 unsigned pg_count = 0;
896 unsigned next_pg_num;
897 bool use_blk_mq = dm_use_blk_mq(dm_table_get_md(ti->table));
898
899 as.argc = argc;
900 as.argv = argv;
901
902 m = alloc_multipath(ti, use_blk_mq);
903 if (!m) {
904 ti->error = "can't allocate multipath";
905 return -EINVAL;
906 }
907
908 r = parse_features(&as, m);
909 if (r)
910 goto bad;
911
912 r = parse_hw_handler(&as, m);
913 if (r)
914 goto bad;
915
916 r = dm_read_arg(_args, &as, &m->nr_priority_groups, &ti->error);
917 if (r)
918 goto bad;
919
920 r = dm_read_arg(_args + 1, &as, &next_pg_num, &ti->error);
921 if (r)
922 goto bad;
923
924 if ((!m->nr_priority_groups && next_pg_num) ||
925 (m->nr_priority_groups && !next_pg_num)) {
926 ti->error = "invalid initial priority group";
927 r = -EINVAL;
928 goto bad;
929 }
930
931 /* parse the priority groups */
932 while (as.argc) {
933 struct priority_group *pg;
934 unsigned nr_valid_paths = atomic_read(&m->nr_valid_paths);
935
936 pg = parse_priority_group(&as, m);
937 if (IS_ERR(pg)) {
938 r = PTR_ERR(pg);
939 goto bad;
940 }
941
942 nr_valid_paths += pg->nr_pgpaths;
943 atomic_set(&m->nr_valid_paths, nr_valid_paths);
944
945 list_add_tail(&pg->list, &m->priority_groups);
946 pg_count++;
947 pg->pg_num = pg_count;
948 if (!--next_pg_num)
949 m->next_pg = pg;
950 }
951
952 if (pg_count != m->nr_priority_groups) {
953 ti->error = "priority group count mismatch";
954 r = -EINVAL;
955 goto bad;
956 }
957
958 ti->num_flush_bios = 1;
959 ti->num_discard_bios = 1;
960 ti->num_write_same_bios = 1;
961 if (use_blk_mq)
962 ti->per_io_data_size = sizeof(struct dm_mpath_io);
963
964 return 0;
965
966 bad:
967 free_multipath(m);
968 return r;
969 }
970
971 static void multipath_wait_for_pg_init_completion(struct multipath *m)
972 {
973 DECLARE_WAITQUEUE(wait, current);
974
975 add_wait_queue(&m->pg_init_wait, &wait);
976
977 while (1) {
978 set_current_state(TASK_UNINTERRUPTIBLE);
979
980 if (!atomic_read(&m->pg_init_in_progress))
981 break;
982
983 io_schedule();
984 }
985 set_current_state(TASK_RUNNING);
986
987 remove_wait_queue(&m->pg_init_wait, &wait);
988 }
989
990 static void flush_multipath_work(struct multipath *m)
991 {
992 set_bit(MPATHF_PG_INIT_DISABLED, &m->flags);
993 smp_mb__after_atomic();
994
995 flush_workqueue(kmpath_handlerd);
996 multipath_wait_for_pg_init_completion(m);
997 flush_workqueue(kmultipathd);
998 flush_work(&m->trigger_event);
999
1000 clear_bit(MPATHF_PG_INIT_DISABLED, &m->flags);
1001 smp_mb__after_atomic();
1002 }
1003
1004 static void multipath_dtr(struct dm_target *ti)
1005 {
1006 struct multipath *m = ti->private;
1007
1008 flush_multipath_work(m);
1009 free_multipath(m);
1010 }
1011
1012 /*
1013 * Take a path out of use.
1014 */
1015 static int fail_path(struct pgpath *pgpath)
1016 {
1017 unsigned long flags;
1018 struct multipath *m = pgpath->pg->m;
1019
1020 spin_lock_irqsave(&m->lock, flags);
1021
1022 if (!pgpath->is_active)
1023 goto out;
1024
1025 DMWARN("Failing path %s.", pgpath->path.dev->name);
1026
1027 pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
1028 pgpath->is_active = false;
1029 pgpath->fail_count++;
1030
1031 atomic_dec(&m->nr_valid_paths);
1032
1033 if (pgpath == m->current_pgpath)
1034 m->current_pgpath = NULL;
1035
1036 dm_path_uevent(DM_UEVENT_PATH_FAILED, m->ti,
1037 pgpath->path.dev->name, atomic_read(&m->nr_valid_paths));
1038
1039 schedule_work(&m->trigger_event);
1040
1041 out:
1042 spin_unlock_irqrestore(&m->lock, flags);
1043
1044 return 0;
1045 }
1046
1047 /*
1048 * Reinstate a previously-failed path
1049 */
1050 static int reinstate_path(struct pgpath *pgpath)
1051 {
1052 int r = 0, run_queue = 0;
1053 unsigned long flags;
1054 struct multipath *m = pgpath->pg->m;
1055 unsigned nr_valid_paths;
1056
1057 spin_lock_irqsave(&m->lock, flags);
1058
1059 if (pgpath->is_active)
1060 goto out;
1061
1062 DMWARN("Reinstating path %s.", pgpath->path.dev->name);
1063
1064 r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
1065 if (r)
1066 goto out;
1067
1068 pgpath->is_active = true;
1069
1070 nr_valid_paths = atomic_inc_return(&m->nr_valid_paths);
1071 if (nr_valid_paths == 1) {
1072 m->current_pgpath = NULL;
1073 run_queue = 1;
1074 } else if (m->hw_handler_name && (m->current_pg == pgpath->pg)) {
1075 if (queue_work(kmpath_handlerd, &pgpath->activate_path.work))
1076 atomic_inc(&m->pg_init_in_progress);
1077 }
1078
1079 dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti,
1080 pgpath->path.dev->name, nr_valid_paths);
1081
1082 schedule_work(&m->trigger_event);
1083
1084 out:
1085 spin_unlock_irqrestore(&m->lock, flags);
1086 if (run_queue)
1087 dm_table_run_md_queue_async(m->ti->table);
1088
1089 return r;
1090 }
1091
1092 /*
1093 * Fail or reinstate all paths that match the provided struct dm_dev.
1094 */
1095 static int action_dev(struct multipath *m, struct dm_dev *dev,
1096 action_fn action)
1097 {
1098 int r = -EINVAL;
1099 struct pgpath *pgpath;
1100 struct priority_group *pg;
1101
1102 list_for_each_entry(pg, &m->priority_groups, list) {
1103 list_for_each_entry(pgpath, &pg->pgpaths, list) {
1104 if (pgpath->path.dev == dev)
1105 r = action(pgpath);
1106 }
1107 }
1108
1109 return r;
1110 }
1111
1112 /*
1113 * Temporarily try to avoid having to use the specified PG
1114 */
1115 static void bypass_pg(struct multipath *m, struct priority_group *pg,
1116 bool bypassed)
1117 {
1118 unsigned long flags;
1119
1120 spin_lock_irqsave(&m->lock, flags);
1121
1122 pg->bypassed = bypassed;
1123 m->current_pgpath = NULL;
1124 m->current_pg = NULL;
1125
1126 spin_unlock_irqrestore(&m->lock, flags);
1127
1128 schedule_work(&m->trigger_event);
1129 }
1130
1131 /*
1132 * Switch to using the specified PG from the next I/O that gets mapped
1133 */
1134 static int switch_pg_num(struct multipath *m, const char *pgstr)
1135 {
1136 struct priority_group *pg;
1137 unsigned pgnum;
1138 unsigned long flags;
1139 char dummy;
1140
1141 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1142 (pgnum > m->nr_priority_groups)) {
1143 DMWARN("invalid PG number supplied to switch_pg_num");
1144 return -EINVAL;
1145 }
1146
1147 spin_lock_irqsave(&m->lock, flags);
1148 list_for_each_entry(pg, &m->priority_groups, list) {
1149 pg->bypassed = false;
1150 if (--pgnum)
1151 continue;
1152
1153 m->current_pgpath = NULL;
1154 m->current_pg = NULL;
1155 m->next_pg = pg;
1156 }
1157 spin_unlock_irqrestore(&m->lock, flags);
1158
1159 schedule_work(&m->trigger_event);
1160 return 0;
1161 }
1162
1163 /*
1164 * Set/clear bypassed status of a PG.
1165 * PGs are numbered upwards from 1 in the order they were declared.
1166 */
1167 static int bypass_pg_num(struct multipath *m, const char *pgstr, bool bypassed)
1168 {
1169 struct priority_group *pg;
1170 unsigned pgnum;
1171 char dummy;
1172
1173 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1174 (pgnum > m->nr_priority_groups)) {
1175 DMWARN("invalid PG number supplied to bypass_pg");
1176 return -EINVAL;
1177 }
1178
1179 list_for_each_entry(pg, &m->priority_groups, list) {
1180 if (!--pgnum)
1181 break;
1182 }
1183
1184 bypass_pg(m, pg, bypassed);
1185 return 0;
1186 }
1187
1188 /*
1189 * Should we retry pg_init immediately?
1190 */
1191 static bool pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath)
1192 {
1193 unsigned long flags;
1194 bool limit_reached = false;
1195
1196 spin_lock_irqsave(&m->lock, flags);
1197
1198 if (atomic_read(&m->pg_init_count) <= m->pg_init_retries &&
1199 !test_bit(MPATHF_PG_INIT_DISABLED, &m->flags))
1200 set_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
1201 else
1202 limit_reached = true;
1203
1204 spin_unlock_irqrestore(&m->lock, flags);
1205
1206 return limit_reached;
1207 }
1208
1209 static void pg_init_done(void *data, int errors)
1210 {
1211 struct pgpath *pgpath = data;
1212 struct priority_group *pg = pgpath->pg;
1213 struct multipath *m = pg->m;
1214 unsigned long flags;
1215 bool delay_retry = false;
1216
1217 /* device or driver problems */
1218 switch (errors) {
1219 case SCSI_DH_OK:
1220 break;
1221 case SCSI_DH_NOSYS:
1222 if (!m->hw_handler_name) {
1223 errors = 0;
1224 break;
1225 }
1226 DMERR("Could not failover the device: Handler scsi_dh_%s "
1227 "Error %d.", m->hw_handler_name, errors);
1228 /*
1229 * Fail path for now, so we do not ping pong
1230 */
1231 fail_path(pgpath);
1232 break;
1233 case SCSI_DH_DEV_TEMP_BUSY:
1234 /*
1235 * Probably doing something like FW upgrade on the
1236 * controller so try the other pg.
1237 */
1238 bypass_pg(m, pg, true);
1239 break;
1240 case SCSI_DH_RETRY:
1241 /* Wait before retrying. */
1242 delay_retry = 1;
1243 case SCSI_DH_IMM_RETRY:
1244 case SCSI_DH_RES_TEMP_UNAVAIL:
1245 if (pg_init_limit_reached(m, pgpath))
1246 fail_path(pgpath);
1247 errors = 0;
1248 break;
1249 case SCSI_DH_DEV_OFFLINED:
1250 default:
1251 /*
1252 * We probably do not want to fail the path for a device
1253 * error, but this is what the old dm did. In future
1254 * patches we can do more advanced handling.
1255 */
1256 fail_path(pgpath);
1257 }
1258
1259 spin_lock_irqsave(&m->lock, flags);
1260 if (errors) {
1261 if (pgpath == m->current_pgpath) {
1262 DMERR("Could not failover device. Error %d.", errors);
1263 m->current_pgpath = NULL;
1264 m->current_pg = NULL;
1265 }
1266 } else if (!test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
1267 pg->bypassed = false;
1268
1269 if (atomic_dec_return(&m->pg_init_in_progress) > 0)
1270 /* Activations of other paths are still on going */
1271 goto out;
1272
1273 if (test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags)) {
1274 if (delay_retry)
1275 set_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
1276 else
1277 clear_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
1278
1279 if (__pg_init_all_paths(m))
1280 goto out;
1281 }
1282 clear_bit(MPATHF_QUEUE_IO, &m->flags);
1283
1284 /*
1285 * Wake up any thread waiting to suspend.
1286 */
1287 wake_up(&m->pg_init_wait);
1288
1289 out:
1290 spin_unlock_irqrestore(&m->lock, flags);
1291 }
1292
1293 static void activate_path(struct work_struct *work)
1294 {
1295 struct pgpath *pgpath =
1296 container_of(work, struct pgpath, activate_path.work);
1297
1298 if (pgpath->is_active)
1299 scsi_dh_activate(bdev_get_queue(pgpath->path.dev->bdev),
1300 pg_init_done, pgpath);
1301 else
1302 pg_init_done(pgpath, SCSI_DH_DEV_OFFLINED);
1303 }
1304
1305 static int noretry_error(int error)
1306 {
1307 switch (error) {
1308 case -EOPNOTSUPP:
1309 case -EREMOTEIO:
1310 case -EILSEQ:
1311 case -ENODATA:
1312 case -ENOSPC:
1313 return 1;
1314 }
1315
1316 /* Anything else could be a path failure, so should be retried */
1317 return 0;
1318 }
1319
1320 /*
1321 * end_io handling
1322 */
1323 static int do_end_io(struct multipath *m, struct request *clone,
1324 int error, struct dm_mpath_io *mpio)
1325 {
1326 /*
1327 * We don't queue any clone request inside the multipath target
1328 * during end I/O handling, since those clone requests don't have
1329 * bio clones. If we queue them inside the multipath target,
1330 * we need to make bio clones, that requires memory allocation.
1331 * (See drivers/md/dm.c:end_clone_bio() about why the clone requests
1332 * don't have bio clones.)
1333 * Instead of queueing the clone request here, we queue the original
1334 * request into dm core, which will remake a clone request and
1335 * clone bios for it and resubmit it later.
1336 */
1337 int r = DM_ENDIO_REQUEUE;
1338
1339 if (!error && !clone->errors)
1340 return 0; /* I/O complete */
1341
1342 if (noretry_error(error))
1343 return error;
1344
1345 if (mpio->pgpath)
1346 fail_path(mpio->pgpath);
1347
1348 if (!atomic_read(&m->nr_valid_paths)) {
1349 if (!test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
1350 if (!must_push_back(m))
1351 r = -EIO;
1352 } else {
1353 if (error == -EBADE)
1354 r = error;
1355 }
1356 }
1357
1358 return r;
1359 }
1360
1361 static int multipath_end_io(struct dm_target *ti, struct request *clone,
1362 int error, union map_info *map_context)
1363 {
1364 struct multipath *m = ti->private;
1365 struct dm_mpath_io *mpio = get_mpio(map_context);
1366 struct pgpath *pgpath;
1367 struct path_selector *ps;
1368 int r;
1369
1370 BUG_ON(!mpio);
1371
1372 r = do_end_io(m, clone, error, mpio);
1373 pgpath = mpio->pgpath;
1374 if (pgpath) {
1375 ps = &pgpath->pg->ps;
1376 if (ps->type->end_io)
1377 ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
1378 }
1379 clear_request_fn_mpio(m, map_context);
1380
1381 return r;
1382 }
1383
1384 /*
1385 * Suspend can't complete until all the I/O is processed so if
1386 * the last path fails we must error any remaining I/O.
1387 * Note that if the freeze_bdev fails while suspending, the
1388 * queue_if_no_path state is lost - userspace should reset it.
1389 */
1390 static void multipath_presuspend(struct dm_target *ti)
1391 {
1392 struct multipath *m = ti->private;
1393
1394 queue_if_no_path(m, false, true);
1395 }
1396
1397 static void multipath_postsuspend(struct dm_target *ti)
1398 {
1399 struct multipath *m = ti->private;
1400
1401 mutex_lock(&m->work_mutex);
1402 flush_multipath_work(m);
1403 mutex_unlock(&m->work_mutex);
1404 }
1405
1406 /*
1407 * Restore the queue_if_no_path setting.
1408 */
1409 static void multipath_resume(struct dm_target *ti)
1410 {
1411 struct multipath *m = ti->private;
1412
1413 if (test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags))
1414 set_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
1415 else
1416 clear_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
1417 smp_mb__after_atomic();
1418 }
1419
1420 /*
1421 * Info output has the following format:
1422 * num_multipath_feature_args [multipath_feature_args]*
1423 * num_handler_status_args [handler_status_args]*
1424 * num_groups init_group_number
1425 * [A|D|E num_ps_status_args [ps_status_args]*
1426 * num_paths num_selector_args
1427 * [path_dev A|F fail_count [selector_args]* ]+ ]+
1428 *
1429 * Table output has the following format (identical to the constructor string):
1430 * num_feature_args [features_args]*
1431 * num_handler_args hw_handler [hw_handler_args]*
1432 * num_groups init_group_number
1433 * [priority selector-name num_ps_args [ps_args]*
1434 * num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
1435 */
1436 static void multipath_status(struct dm_target *ti, status_type_t type,
1437 unsigned status_flags, char *result, unsigned maxlen)
1438 {
1439 int sz = 0;
1440 unsigned long flags;
1441 struct multipath *m = ti->private;
1442 struct priority_group *pg;
1443 struct pgpath *p;
1444 unsigned pg_num;
1445 char state;
1446
1447 spin_lock_irqsave(&m->lock, flags);
1448
1449 /* Features */
1450 if (type == STATUSTYPE_INFO)
1451 DMEMIT("2 %u %u ", test_bit(MPATHF_QUEUE_IO, &m->flags),
1452 atomic_read(&m->pg_init_count));
1453 else {
1454 DMEMIT("%u ", test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) +
1455 (m->pg_init_retries > 0) * 2 +
1456 (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT) * 2 +
1457 test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags));
1458 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
1459 DMEMIT("queue_if_no_path ");
1460 if (m->pg_init_retries)
1461 DMEMIT("pg_init_retries %u ", m->pg_init_retries);
1462 if (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT)
1463 DMEMIT("pg_init_delay_msecs %u ", m->pg_init_delay_msecs);
1464 if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags))
1465 DMEMIT("retain_attached_hw_handler ");
1466 }
1467
1468 if (!m->hw_handler_name || type == STATUSTYPE_INFO)
1469 DMEMIT("0 ");
1470 else
1471 DMEMIT("1 %s ", m->hw_handler_name);
1472
1473 DMEMIT("%u ", m->nr_priority_groups);
1474
1475 if (m->next_pg)
1476 pg_num = m->next_pg->pg_num;
1477 else if (m->current_pg)
1478 pg_num = m->current_pg->pg_num;
1479 else
1480 pg_num = (m->nr_priority_groups ? 1 : 0);
1481
1482 DMEMIT("%u ", pg_num);
1483
1484 switch (type) {
1485 case STATUSTYPE_INFO:
1486 list_for_each_entry(pg, &m->priority_groups, list) {
1487 if (pg->bypassed)
1488 state = 'D'; /* Disabled */
1489 else if (pg == m->current_pg)
1490 state = 'A'; /* Currently Active */
1491 else
1492 state = 'E'; /* Enabled */
1493
1494 DMEMIT("%c ", state);
1495
1496 if (pg->ps.type->status)
1497 sz += pg->ps.type->status(&pg->ps, NULL, type,
1498 result + sz,
1499 maxlen - sz);
1500 else
1501 DMEMIT("0 ");
1502
1503 DMEMIT("%u %u ", pg->nr_pgpaths,
1504 pg->ps.type->info_args);
1505
1506 list_for_each_entry(p, &pg->pgpaths, list) {
1507 DMEMIT("%s %s %u ", p->path.dev->name,
1508 p->is_active ? "A" : "F",
1509 p->fail_count);
1510 if (pg->ps.type->status)
1511 sz += pg->ps.type->status(&pg->ps,
1512 &p->path, type, result + sz,
1513 maxlen - sz);
1514 }
1515 }
1516 break;
1517
1518 case STATUSTYPE_TABLE:
1519 list_for_each_entry(pg, &m->priority_groups, list) {
1520 DMEMIT("%s ", pg->ps.type->name);
1521
1522 if (pg->ps.type->status)
1523 sz += pg->ps.type->status(&pg->ps, NULL, type,
1524 result + sz,
1525 maxlen - sz);
1526 else
1527 DMEMIT("0 ");
1528
1529 DMEMIT("%u %u ", pg->nr_pgpaths,
1530 pg->ps.type->table_args);
1531
1532 list_for_each_entry(p, &pg->pgpaths, list) {
1533 DMEMIT("%s ", p->path.dev->name);
1534 if (pg->ps.type->status)
1535 sz += pg->ps.type->status(&pg->ps,
1536 &p->path, type, result + sz,
1537 maxlen - sz);
1538 }
1539 }
1540 break;
1541 }
1542
1543 spin_unlock_irqrestore(&m->lock, flags);
1544 }
1545
1546 static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
1547 {
1548 int r = -EINVAL;
1549 struct dm_dev *dev;
1550 struct multipath *m = ti->private;
1551 action_fn action;
1552
1553 mutex_lock(&m->work_mutex);
1554
1555 if (dm_suspended(ti)) {
1556 r = -EBUSY;
1557 goto out;
1558 }
1559
1560 if (argc == 1) {
1561 if (!strcasecmp(argv[0], "queue_if_no_path")) {
1562 r = queue_if_no_path(m, true, false);
1563 goto out;
1564 } else if (!strcasecmp(argv[0], "fail_if_no_path")) {
1565 r = queue_if_no_path(m, false, false);
1566 goto out;
1567 }
1568 }
1569
1570 if (argc != 2) {
1571 DMWARN("Invalid multipath message arguments. Expected 2 arguments, got %d.", argc);
1572 goto out;
1573 }
1574
1575 if (!strcasecmp(argv[0], "disable_group")) {
1576 r = bypass_pg_num(m, argv[1], true);
1577 goto out;
1578 } else if (!strcasecmp(argv[0], "enable_group")) {
1579 r = bypass_pg_num(m, argv[1], false);
1580 goto out;
1581 } else if (!strcasecmp(argv[0], "switch_group")) {
1582 r = switch_pg_num(m, argv[1]);
1583 goto out;
1584 } else if (!strcasecmp(argv[0], "reinstate_path"))
1585 action = reinstate_path;
1586 else if (!strcasecmp(argv[0], "fail_path"))
1587 action = fail_path;
1588 else {
1589 DMWARN("Unrecognised multipath message received: %s", argv[0]);
1590 goto out;
1591 }
1592
1593 r = dm_get_device(ti, argv[1], dm_table_get_mode(ti->table), &dev);
1594 if (r) {
1595 DMWARN("message: error getting device %s",
1596 argv[1]);
1597 goto out;
1598 }
1599
1600 r = action_dev(m, dev, action);
1601
1602 dm_put_device(ti, dev);
1603
1604 out:
1605 mutex_unlock(&m->work_mutex);
1606 return r;
1607 }
1608
1609 static int multipath_prepare_ioctl(struct dm_target *ti,
1610 struct block_device **bdev, fmode_t *mode)
1611 {
1612 struct multipath *m = ti->private;
1613 struct pgpath *current_pgpath;
1614 int r;
1615
1616 current_pgpath = lockless_dereference(m->current_pgpath);
1617 if (!current_pgpath)
1618 current_pgpath = choose_pgpath(m, 0);
1619
1620 if (current_pgpath) {
1621 if (!test_bit(MPATHF_QUEUE_IO, &m->flags)) {
1622 *bdev = current_pgpath->path.dev->bdev;
1623 *mode = current_pgpath->path.dev->mode;
1624 r = 0;
1625 } else {
1626 /* pg_init has not started or completed */
1627 r = -ENOTCONN;
1628 }
1629 } else {
1630 /* No path is available */
1631 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
1632 r = -ENOTCONN;
1633 else
1634 r = -EIO;
1635 }
1636
1637 if (r == -ENOTCONN) {
1638 if (!lockless_dereference(m->current_pg)) {
1639 /* Path status changed, redo selection */
1640 (void) choose_pgpath(m, 0);
1641 }
1642 if (test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
1643 pg_init_all_paths(m);
1644 dm_table_run_md_queue_async(m->ti->table);
1645 }
1646
1647 /*
1648 * Only pass ioctls through if the device sizes match exactly.
1649 */
1650 if (!r && ti->len != i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT)
1651 return 1;
1652 return r;
1653 }
1654
1655 static int multipath_iterate_devices(struct dm_target *ti,
1656 iterate_devices_callout_fn fn, void *data)
1657 {
1658 struct multipath *m = ti->private;
1659 struct priority_group *pg;
1660 struct pgpath *p;
1661 int ret = 0;
1662
1663 list_for_each_entry(pg, &m->priority_groups, list) {
1664 list_for_each_entry(p, &pg->pgpaths, list) {
1665 ret = fn(ti, p->path.dev, ti->begin, ti->len, data);
1666 if (ret)
1667 goto out;
1668 }
1669 }
1670
1671 out:
1672 return ret;
1673 }
1674
1675 static int pgpath_busy(struct pgpath *pgpath)
1676 {
1677 struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
1678
1679 return blk_lld_busy(q);
1680 }
1681
1682 /*
1683 * We return "busy", only when we can map I/Os but underlying devices
1684 * are busy (so even if we map I/Os now, the I/Os will wait on
1685 * the underlying queue).
1686 * In other words, if we want to kill I/Os or queue them inside us
1687 * due to map unavailability, we don't return "busy". Otherwise,
1688 * dm core won't give us the I/Os and we can't do what we want.
1689 */
1690 static int multipath_busy(struct dm_target *ti)
1691 {
1692 bool busy = false, has_active = false;
1693 struct multipath *m = ti->private;
1694 struct priority_group *pg, *next_pg;
1695 struct pgpath *pgpath;
1696
1697 /* pg_init in progress or no paths available */
1698 if (atomic_read(&m->pg_init_in_progress) ||
1699 (!atomic_read(&m->nr_valid_paths) && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)))
1700 return true;
1701
1702 /* Guess which priority_group will be used at next mapping time */
1703 pg = lockless_dereference(m->current_pg);
1704 next_pg = lockless_dereference(m->next_pg);
1705 if (unlikely(!lockless_dereference(m->current_pgpath) && next_pg))
1706 pg = next_pg;
1707
1708 if (!pg) {
1709 /*
1710 * We don't know which pg will be used at next mapping time.
1711 * We don't call choose_pgpath() here to avoid to trigger
1712 * pg_init just by busy checking.
1713 * So we don't know whether underlying devices we will be using
1714 * at next mapping time are busy or not. Just try mapping.
1715 */
1716 return busy;
1717 }
1718
1719 /*
1720 * If there is one non-busy active path at least, the path selector
1721 * will be able to select it. So we consider such a pg as not busy.
1722 */
1723 busy = true;
1724 list_for_each_entry(pgpath, &pg->pgpaths, list) {
1725 if (pgpath->is_active) {
1726 has_active = true;
1727 if (!pgpath_busy(pgpath)) {
1728 busy = false;
1729 break;
1730 }
1731 }
1732 }
1733
1734 if (!has_active) {
1735 /*
1736 * No active path in this pg, so this pg won't be used and
1737 * the current_pg will be changed at next mapping time.
1738 * We need to try mapping to determine it.
1739 */
1740 busy = false;
1741 }
1742
1743 return busy;
1744 }
1745
1746 /*-----------------------------------------------------------------
1747 * Module setup
1748 *---------------------------------------------------------------*/
1749 static struct target_type multipath_target = {
1750 .name = "multipath",
1751 .version = {1, 11, 0},
1752 .features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE,
1753 .module = THIS_MODULE,
1754 .ctr = multipath_ctr,
1755 .dtr = multipath_dtr,
1756 .map_rq = multipath_map,
1757 .clone_and_map_rq = multipath_clone_and_map,
1758 .release_clone_rq = multipath_release_clone,
1759 .rq_end_io = multipath_end_io,
1760 .presuspend = multipath_presuspend,
1761 .postsuspend = multipath_postsuspend,
1762 .resume = multipath_resume,
1763 .status = multipath_status,
1764 .message = multipath_message,
1765 .prepare_ioctl = multipath_prepare_ioctl,
1766 .iterate_devices = multipath_iterate_devices,
1767 .busy = multipath_busy,
1768 };
1769
1770 static int __init dm_multipath_init(void)
1771 {
1772 int r;
1773
1774 /* allocate a slab for the dm_ios */
1775 _mpio_cache = KMEM_CACHE(dm_mpath_io, 0);
1776 if (!_mpio_cache)
1777 return -ENOMEM;
1778
1779 r = dm_register_target(&multipath_target);
1780 if (r < 0) {
1781 DMERR("register failed %d", r);
1782 r = -EINVAL;
1783 goto bad_register_target;
1784 }
1785
1786 kmultipathd = alloc_workqueue("kmpathd", WQ_MEM_RECLAIM, 0);
1787 if (!kmultipathd) {
1788 DMERR("failed to create workqueue kmpathd");
1789 r = -ENOMEM;
1790 goto bad_alloc_kmultipathd;
1791 }
1792
1793 /*
1794 * A separate workqueue is used to handle the device handlers
1795 * to avoid overloading existing workqueue. Overloading the
1796 * old workqueue would also create a bottleneck in the
1797 * path of the storage hardware device activation.
1798 */
1799 kmpath_handlerd = alloc_ordered_workqueue("kmpath_handlerd",
1800 WQ_MEM_RECLAIM);
1801 if (!kmpath_handlerd) {
1802 DMERR("failed to create workqueue kmpath_handlerd");
1803 r = -ENOMEM;
1804 goto bad_alloc_kmpath_handlerd;
1805 }
1806
1807 DMINFO("version %u.%u.%u loaded",
1808 multipath_target.version[0], multipath_target.version[1],
1809 multipath_target.version[2]);
1810
1811 return 0;
1812
1813 bad_alloc_kmpath_handlerd:
1814 destroy_workqueue(kmultipathd);
1815 bad_alloc_kmultipathd:
1816 dm_unregister_target(&multipath_target);
1817 bad_register_target:
1818 kmem_cache_destroy(_mpio_cache);
1819
1820 return r;
1821 }
1822
1823 static void __exit dm_multipath_exit(void)
1824 {
1825 destroy_workqueue(kmpath_handlerd);
1826 destroy_workqueue(kmultipathd);
1827
1828 dm_unregister_target(&multipath_target);
1829 kmem_cache_destroy(_mpio_cache);
1830 }
1831
1832 module_init(dm_multipath_init);
1833 module_exit(dm_multipath_exit);
1834
1835 MODULE_DESCRIPTION(DM_NAME " multipath target");
1836 MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
1837 MODULE_LICENSE("GPL");
Linux kernel - Deliverables
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