dm target:s introduce iterate devices fn
[linux-2.6.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-bio-record.h"
12 #include "dm-uevent.h"
13
14 #include <linux/ctype.h>
15 #include <linux/init.h>
16 #include <linux/mempool.h>
17 #include <linux/module.h>
18 #include <linux/pagemap.h>
19 #include <linux/slab.h>
20 #include <linux/time.h>
21 #include <linux/workqueue.h>
22 #include <scsi/scsi_dh.h>
23 #include <asm/atomic.h>
24
25 #define DM_MSG_PREFIX "multipath"
26 #define MESG_STR(x) x, sizeof(x)
27
28 /* Path properties */
29 struct pgpath {
30         struct list_head list;
31
32         struct priority_group *pg;      /* Owning PG */
33         unsigned is_active;             /* Path status */
34         unsigned fail_count;            /* Cumulative failure count */
35
36         struct dm_path path;
37         struct work_struct deactivate_path;
38         struct work_struct 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         spinlock_t lock;
66
67         const char *hw_handler_name;
68         unsigned nr_priority_groups;
69         struct list_head priority_groups;
70         unsigned pg_init_required;      /* pg_init needs calling? */
71         unsigned pg_init_in_progress;   /* Only one pg_init allowed at once */
72
73         unsigned nr_valid_paths;        /* Total number of usable paths */
74         struct pgpath *current_pgpath;
75         struct priority_group *current_pg;
76         struct priority_group *next_pg; /* Switch to this PG if set */
77         unsigned repeat_count;          /* I/Os left before calling PS again */
78
79         unsigned queue_io;              /* Must we queue all I/O? */
80         unsigned queue_if_no_path;      /* Queue I/O if last path fails? */
81         unsigned saved_queue_if_no_path;/* Saved state during suspension */
82         unsigned pg_init_retries;       /* Number of times to retry pg_init */
83         unsigned pg_init_count;         /* Number of times pg_init called */
84
85         struct work_struct process_queued_ios;
86         struct bio_list queued_ios;
87         unsigned queue_size;
88
89         struct work_struct trigger_event;
90
91         /*
92          * We must use a mempool of dm_mpath_io structs so that we
93          * can resubmit bios on error.
94          */
95         mempool_t *mpio_pool;
96 };
97
98 /*
99  * Context information attached to each bio we process.
100  */
101 struct dm_mpath_io {
102         struct pgpath *pgpath;
103         struct dm_bio_details details;
104         size_t nr_bytes;
105 };
106
107 typedef int (*action_fn) (struct pgpath *pgpath);
108
109 #define MIN_IOS 256     /* Mempool size */
110
111 static struct kmem_cache *_mpio_cache;
112
113 static struct workqueue_struct *kmultipathd, *kmpath_handlerd;
114 static void process_queued_ios(struct work_struct *work);
115 static void trigger_event(struct work_struct *work);
116 static void activate_path(struct work_struct *work);
117 static void deactivate_path(struct work_struct *work);
118
119
120 /*-----------------------------------------------
121  * Allocation routines
122  *-----------------------------------------------*/
123
124 static struct pgpath *alloc_pgpath(void)
125 {
126         struct pgpath *pgpath = kzalloc(sizeof(*pgpath), GFP_KERNEL);
127
128         if (pgpath) {
129                 pgpath->is_active = 1;
130                 INIT_WORK(&pgpath->deactivate_path, deactivate_path);
131                 INIT_WORK(&pgpath->activate_path, activate_path);
132         }
133
134         return pgpath;
135 }
136
137 static void free_pgpath(struct pgpath *pgpath)
138 {
139         kfree(pgpath);
140 }
141
142 static void deactivate_path(struct work_struct *work)
143 {
144         struct pgpath *pgpath =
145                 container_of(work, struct pgpath, deactivate_path);
146
147         blk_abort_queue(pgpath->path.dev->bdev->bd_disk->queue);
148 }
149
150 static struct priority_group *alloc_priority_group(void)
151 {
152         struct priority_group *pg;
153
154         pg = kzalloc(sizeof(*pg), GFP_KERNEL);
155
156         if (pg)
157                 INIT_LIST_HEAD(&pg->pgpaths);
158
159         return pg;
160 }
161
162 static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti)
163 {
164         struct pgpath *pgpath, *tmp;
165         struct multipath *m = ti->private;
166
167         list_for_each_entry_safe(pgpath, tmp, pgpaths, list) {
168                 list_del(&pgpath->list);
169                 if (m->hw_handler_name)
170                         scsi_dh_detach(bdev_get_queue(pgpath->path.dev->bdev));
171                 dm_put_device(ti, pgpath->path.dev);
172                 free_pgpath(pgpath);
173         }
174 }
175
176 static void free_priority_group(struct priority_group *pg,
177                                 struct dm_target *ti)
178 {
179         struct path_selector *ps = &pg->ps;
180
181         if (ps->type) {
182                 ps->type->destroy(ps);
183                 dm_put_path_selector(ps->type);
184         }
185
186         free_pgpaths(&pg->pgpaths, ti);
187         kfree(pg);
188 }
189
190 static struct multipath *alloc_multipath(struct dm_target *ti)
191 {
192         struct multipath *m;
193
194         m = kzalloc(sizeof(*m), GFP_KERNEL);
195         if (m) {
196                 INIT_LIST_HEAD(&m->priority_groups);
197                 spin_lock_init(&m->lock);
198                 m->queue_io = 1;
199                 INIT_WORK(&m->process_queued_ios, process_queued_ios);
200                 INIT_WORK(&m->trigger_event, trigger_event);
201                 m->mpio_pool = mempool_create_slab_pool(MIN_IOS, _mpio_cache);
202                 if (!m->mpio_pool) {
203                         kfree(m);
204                         return NULL;
205                 }
206                 m->ti = ti;
207                 ti->private = m;
208         }
209
210         return m;
211 }
212
213 static void free_multipath(struct multipath *m)
214 {
215         struct priority_group *pg, *tmp;
216
217         list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) {
218                 list_del(&pg->list);
219                 free_priority_group(pg, m->ti);
220         }
221
222         kfree(m->hw_handler_name);
223         mempool_destroy(m->mpio_pool);
224         kfree(m);
225 }
226
227
228 /*-----------------------------------------------
229  * Path selection
230  *-----------------------------------------------*/
231
232 static void __switch_pg(struct multipath *m, struct pgpath *pgpath)
233 {
234         m->current_pg = pgpath->pg;
235
236         /* Must we initialise the PG first, and queue I/O till it's ready? */
237         if (m->hw_handler_name) {
238                 m->pg_init_required = 1;
239                 m->queue_io = 1;
240         } else {
241                 m->pg_init_required = 0;
242                 m->queue_io = 0;
243         }
244
245         m->pg_init_count = 0;
246 }
247
248 static int __choose_path_in_pg(struct multipath *m, struct priority_group *pg,
249                                size_t nr_bytes)
250 {
251         struct dm_path *path;
252
253         path = pg->ps.type->select_path(&pg->ps, &m->repeat_count, nr_bytes);
254         if (!path)
255                 return -ENXIO;
256
257         m->current_pgpath = path_to_pgpath(path);
258
259         if (m->current_pg != pg)
260                 __switch_pg(m, m->current_pgpath);
261
262         return 0;
263 }
264
265 static void __choose_pgpath(struct multipath *m, size_t nr_bytes)
266 {
267         struct priority_group *pg;
268         unsigned bypassed = 1;
269
270         if (!m->nr_valid_paths)
271                 goto failed;
272
273         /* Were we instructed to switch PG? */
274         if (m->next_pg) {
275                 pg = m->next_pg;
276                 m->next_pg = NULL;
277                 if (!__choose_path_in_pg(m, pg, nr_bytes))
278                         return;
279         }
280
281         /* Don't change PG until it has no remaining paths */
282         if (m->current_pg && !__choose_path_in_pg(m, m->current_pg, nr_bytes))
283                 return;
284
285         /*
286          * Loop through priority groups until we find a valid path.
287          * First time we skip PGs marked 'bypassed'.
288          * Second time we only try the ones we skipped.
289          */
290         do {
291                 list_for_each_entry(pg, &m->priority_groups, list) {
292                         if (pg->bypassed == bypassed)
293                                 continue;
294                         if (!__choose_path_in_pg(m, pg, nr_bytes))
295                                 return;
296                 }
297         } while (bypassed--);
298
299 failed:
300         m->current_pgpath = NULL;
301         m->current_pg = NULL;
302 }
303
304 /*
305  * Check whether bios must be queued in the device-mapper core rather
306  * than here in the target.
307  *
308  * m->lock must be held on entry.
309  *
310  * If m->queue_if_no_path and m->saved_queue_if_no_path hold the
311  * same value then we are not between multipath_presuspend()
312  * and multipath_resume() calls and we have no need to check
313  * for the DMF_NOFLUSH_SUSPENDING flag.
314  */
315 static int __must_push_back(struct multipath *m)
316 {
317         return (m->queue_if_no_path != m->saved_queue_if_no_path &&
318                 dm_noflush_suspending(m->ti));
319 }
320
321 static int map_io(struct multipath *m, struct bio *bio,
322                   struct dm_mpath_io *mpio, unsigned was_queued)
323 {
324         int r = DM_MAPIO_REMAPPED;
325         size_t nr_bytes = bio->bi_size;
326         unsigned long flags;
327         struct pgpath *pgpath;
328
329         spin_lock_irqsave(&m->lock, flags);
330
331         /* Do we need to select a new pgpath? */
332         if (!m->current_pgpath ||
333             (!m->queue_io && (m->repeat_count && --m->repeat_count == 0)))
334                 __choose_pgpath(m, nr_bytes);
335
336         pgpath = m->current_pgpath;
337
338         if (was_queued)
339                 m->queue_size--;
340
341         if ((pgpath && m->queue_io) ||
342             (!pgpath && m->queue_if_no_path)) {
343                 /* Queue for the daemon to resubmit */
344                 bio_list_add(&m->queued_ios, bio);
345                 m->queue_size++;
346                 if ((m->pg_init_required && !m->pg_init_in_progress) ||
347                     !m->queue_io)
348                         queue_work(kmultipathd, &m->process_queued_ios);
349                 pgpath = NULL;
350                 r = DM_MAPIO_SUBMITTED;
351         } else if (pgpath)
352                 bio->bi_bdev = pgpath->path.dev->bdev;
353         else if (__must_push_back(m))
354                 r = DM_MAPIO_REQUEUE;
355         else
356                 r = -EIO;       /* Failed */
357
358         mpio->pgpath = pgpath;
359         mpio->nr_bytes = nr_bytes;
360
361         if (r == DM_MAPIO_REMAPPED && pgpath->pg->ps.type->start_io)
362                 pgpath->pg->ps.type->start_io(&pgpath->pg->ps, &pgpath->path,
363                                               nr_bytes);
364
365         spin_unlock_irqrestore(&m->lock, flags);
366
367         return r;
368 }
369
370 /*
371  * If we run out of usable paths, should we queue I/O or error it?
372  */
373 static int queue_if_no_path(struct multipath *m, unsigned queue_if_no_path,
374                             unsigned save_old_value)
375 {
376         unsigned long flags;
377
378         spin_lock_irqsave(&m->lock, flags);
379
380         if (save_old_value)
381                 m->saved_queue_if_no_path = m->queue_if_no_path;
382         else
383                 m->saved_queue_if_no_path = queue_if_no_path;
384         m->queue_if_no_path = queue_if_no_path;
385         if (!m->queue_if_no_path && m->queue_size)
386                 queue_work(kmultipathd, &m->process_queued_ios);
387
388         spin_unlock_irqrestore(&m->lock, flags);
389
390         return 0;
391 }
392
393 /*-----------------------------------------------------------------
394  * The multipath daemon is responsible for resubmitting queued ios.
395  *---------------------------------------------------------------*/
396
397 static void dispatch_queued_ios(struct multipath *m)
398 {
399         int r;
400         unsigned long flags;
401         struct bio *bio = NULL, *next;
402         struct dm_mpath_io *mpio;
403         union map_info *info;
404
405         spin_lock_irqsave(&m->lock, flags);
406         bio = bio_list_get(&m->queued_ios);
407         spin_unlock_irqrestore(&m->lock, flags);
408
409         while (bio) {
410                 next = bio->bi_next;
411                 bio->bi_next = NULL;
412
413                 info = dm_get_mapinfo(bio);
414                 mpio = info->ptr;
415
416                 r = map_io(m, bio, mpio, 1);
417                 if (r < 0)
418                         bio_endio(bio, r);
419                 else if (r == DM_MAPIO_REMAPPED)
420                         generic_make_request(bio);
421                 else if (r == DM_MAPIO_REQUEUE)
422                         bio_endio(bio, -EIO);
423
424                 bio = next;
425         }
426 }
427
428 static void process_queued_ios(struct work_struct *work)
429 {
430         struct multipath *m =
431                 container_of(work, struct multipath, process_queued_ios);
432         struct pgpath *pgpath = NULL, *tmp;
433         unsigned must_queue = 1;
434         unsigned long flags;
435
436         spin_lock_irqsave(&m->lock, flags);
437
438         if (!m->queue_size)
439                 goto out;
440
441         if (!m->current_pgpath)
442                 __choose_pgpath(m, 0);
443
444         pgpath = m->current_pgpath;
445
446         if ((pgpath && !m->queue_io) ||
447             (!pgpath && !m->queue_if_no_path))
448                 must_queue = 0;
449
450         if (m->pg_init_required && !m->pg_init_in_progress && pgpath) {
451                 m->pg_init_count++;
452                 m->pg_init_required = 0;
453                 list_for_each_entry(tmp, &pgpath->pg->pgpaths, list) {
454                         if (queue_work(kmpath_handlerd, &tmp->activate_path))
455                                 m->pg_init_in_progress++;
456                 }
457         }
458 out:
459         spin_unlock_irqrestore(&m->lock, flags);
460         if (!must_queue)
461                 dispatch_queued_ios(m);
462 }
463
464 /*
465  * An event is triggered whenever a path is taken out of use.
466  * Includes path failure and PG bypass.
467  */
468 static void trigger_event(struct work_struct *work)
469 {
470         struct multipath *m =
471                 container_of(work, struct multipath, trigger_event);
472
473         dm_table_event(m->ti->table);
474 }
475
476 /*-----------------------------------------------------------------
477  * Constructor/argument parsing:
478  * <#multipath feature args> [<arg>]*
479  * <#hw_handler args> [hw_handler [<arg>]*]
480  * <#priority groups>
481  * <initial priority group>
482  *     [<selector> <#selector args> [<arg>]*
483  *      <#paths> <#per-path selector args>
484  *         [<path> [<arg>]* ]+ ]+
485  *---------------------------------------------------------------*/
486 struct param {
487         unsigned min;
488         unsigned max;
489         char *error;
490 };
491
492 static int read_param(struct param *param, char *str, unsigned *v, char **error)
493 {
494         if (!str ||
495             (sscanf(str, "%u", v) != 1) ||
496             (*v < param->min) ||
497             (*v > param->max)) {
498                 *error = param->error;
499                 return -EINVAL;
500         }
501
502         return 0;
503 }
504
505 struct arg_set {
506         unsigned argc;
507         char **argv;
508 };
509
510 static char *shift(struct arg_set *as)
511 {
512         char *r;
513
514         if (as->argc) {
515                 as->argc--;
516                 r = *as->argv;
517                 as->argv++;
518                 return r;
519         }
520
521         return NULL;
522 }
523
524 static void consume(struct arg_set *as, unsigned n)
525 {
526         BUG_ON (as->argc < n);
527         as->argc -= n;
528         as->argv += n;
529 }
530
531 static int parse_path_selector(struct arg_set *as, struct priority_group *pg,
532                                struct dm_target *ti)
533 {
534         int r;
535         struct path_selector_type *pst;
536         unsigned ps_argc;
537
538         static struct param _params[] = {
539                 {0, 1024, "invalid number of path selector args"},
540         };
541
542         pst = dm_get_path_selector(shift(as));
543         if (!pst) {
544                 ti->error = "unknown path selector type";
545                 return -EINVAL;
546         }
547
548         r = read_param(_params, shift(as), &ps_argc, &ti->error);
549         if (r) {
550                 dm_put_path_selector(pst);
551                 return -EINVAL;
552         }
553
554         if (ps_argc > as->argc) {
555                 dm_put_path_selector(pst);
556                 ti->error = "not enough arguments for path selector";
557                 return -EINVAL;
558         }
559
560         r = pst->create(&pg->ps, ps_argc, as->argv);
561         if (r) {
562                 dm_put_path_selector(pst);
563                 ti->error = "path selector constructor failed";
564                 return r;
565         }
566
567         pg->ps.type = pst;
568         consume(as, ps_argc);
569
570         return 0;
571 }
572
573 static struct pgpath *parse_path(struct arg_set *as, struct path_selector *ps,
574                                struct dm_target *ti)
575 {
576         int r;
577         struct pgpath *p;
578         struct multipath *m = ti->private;
579
580         /* we need at least a path arg */
581         if (as->argc < 1) {
582                 ti->error = "no device given";
583                 return ERR_PTR(-EINVAL);
584         }
585
586         p = alloc_pgpath();
587         if (!p)
588                 return ERR_PTR(-ENOMEM);
589
590         r = dm_get_device(ti, shift(as), ti->begin, ti->len,
591                           dm_table_get_mode(ti->table), &p->path.dev);
592         if (r) {
593                 ti->error = "error getting device";
594                 goto bad;
595         }
596
597         if (m->hw_handler_name) {
598                 struct request_queue *q = bdev_get_queue(p->path.dev->bdev);
599
600                 r = scsi_dh_attach(q, m->hw_handler_name);
601                 if (r == -EBUSY) {
602                         /*
603                          * Already attached to different hw_handler,
604                          * try to reattach with correct one.
605                          */
606                         scsi_dh_detach(q);
607                         r = scsi_dh_attach(q, m->hw_handler_name);
608                 }
609
610                 if (r < 0) {
611                         ti->error = "error attaching hardware handler";
612                         dm_put_device(ti, p->path.dev);
613                         goto bad;
614                 }
615         }
616
617         r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
618         if (r) {
619                 dm_put_device(ti, p->path.dev);
620                 goto bad;
621         }
622
623         return p;
624
625  bad:
626         free_pgpath(p);
627         return ERR_PTR(r);
628 }
629
630 static struct priority_group *parse_priority_group(struct arg_set *as,
631                                                    struct multipath *m)
632 {
633         static struct param _params[] = {
634                 {1, 1024, "invalid number of paths"},
635                 {0, 1024, "invalid number of selector args"}
636         };
637
638         int r;
639         unsigned i, nr_selector_args, nr_params;
640         struct priority_group *pg;
641         struct dm_target *ti = m->ti;
642
643         if (as->argc < 2) {
644                 as->argc = 0;
645                 ti->error = "not enough priority group arguments";
646                 return ERR_PTR(-EINVAL);
647         }
648
649         pg = alloc_priority_group();
650         if (!pg) {
651                 ti->error = "couldn't allocate priority group";
652                 return ERR_PTR(-ENOMEM);
653         }
654         pg->m = m;
655
656         r = parse_path_selector(as, pg, ti);
657         if (r)
658                 goto bad;
659
660         /*
661          * read the paths
662          */
663         r = read_param(_params, shift(as), &pg->nr_pgpaths, &ti->error);
664         if (r)
665                 goto bad;
666
667         r = read_param(_params + 1, shift(as), &nr_selector_args, &ti->error);
668         if (r)
669                 goto bad;
670
671         nr_params = 1 + nr_selector_args;
672         for (i = 0; i < pg->nr_pgpaths; i++) {
673                 struct pgpath *pgpath;
674                 struct arg_set path_args;
675
676                 if (as->argc < nr_params) {
677                         ti->error = "not enough path parameters";
678                         goto bad;
679                 }
680
681                 path_args.argc = nr_params;
682                 path_args.argv = as->argv;
683
684                 pgpath = parse_path(&path_args, &pg->ps, ti);
685                 if (IS_ERR(pgpath)) {
686                         r = PTR_ERR(pgpath);
687                         goto bad;
688                 }
689
690                 pgpath->pg = pg;
691                 list_add_tail(&pgpath->list, &pg->pgpaths);
692                 consume(as, nr_params);
693         }
694
695         return pg;
696
697  bad:
698         free_priority_group(pg, ti);
699         return ERR_PTR(r);
700 }
701
702 static int parse_hw_handler(struct arg_set *as, struct multipath *m)
703 {
704         unsigned hw_argc;
705         struct dm_target *ti = m->ti;
706
707         static struct param _params[] = {
708                 {0, 1024, "invalid number of hardware handler args"},
709         };
710
711         if (read_param(_params, shift(as), &hw_argc, &ti->error))
712                 return -EINVAL;
713
714         if (!hw_argc)
715                 return 0;
716
717         if (hw_argc > as->argc) {
718                 ti->error = "not enough arguments for hardware handler";
719                 return -EINVAL;
720         }
721
722         m->hw_handler_name = kstrdup(shift(as), GFP_KERNEL);
723         request_module("scsi_dh_%s", m->hw_handler_name);
724         if (scsi_dh_handler_exist(m->hw_handler_name) == 0) {
725                 ti->error = "unknown hardware handler type";
726                 kfree(m->hw_handler_name);
727                 m->hw_handler_name = NULL;
728                 return -EINVAL;
729         }
730
731         if (hw_argc > 1)
732                 DMWARN("Ignoring user-specified arguments for "
733                        "hardware handler \"%s\"", m->hw_handler_name);
734         consume(as, hw_argc - 1);
735
736         return 0;
737 }
738
739 static int parse_features(struct arg_set *as, struct multipath *m)
740 {
741         int r;
742         unsigned argc;
743         struct dm_target *ti = m->ti;
744         const char *param_name;
745
746         static struct param _params[] = {
747                 {0, 3, "invalid number of feature args"},
748                 {1, 50, "pg_init_retries must be between 1 and 50"},
749         };
750
751         r = read_param(_params, shift(as), &argc, &ti->error);
752         if (r)
753                 return -EINVAL;
754
755         if (!argc)
756                 return 0;
757
758         do {
759                 param_name = shift(as);
760                 argc--;
761
762                 if (!strnicmp(param_name, MESG_STR("queue_if_no_path"))) {
763                         r = queue_if_no_path(m, 1, 0);
764                         continue;
765                 }
766
767                 if (!strnicmp(param_name, MESG_STR("pg_init_retries")) &&
768                     (argc >= 1)) {
769                         r = read_param(_params + 1, shift(as),
770                                        &m->pg_init_retries, &ti->error);
771                         argc--;
772                         continue;
773                 }
774
775                 ti->error = "Unrecognised multipath feature request";
776                 r = -EINVAL;
777         } while (argc && !r);
778
779         return r;
780 }
781
782 static int multipath_ctr(struct dm_target *ti, unsigned int argc,
783                          char **argv)
784 {
785         /* target parameters */
786         static struct param _params[] = {
787                 {1, 1024, "invalid number of priority groups"},
788                 {1, 1024, "invalid initial priority group number"},
789         };
790
791         int r;
792         struct multipath *m;
793         struct arg_set as;
794         unsigned pg_count = 0;
795         unsigned next_pg_num;
796
797         as.argc = argc;
798         as.argv = argv;
799
800         m = alloc_multipath(ti);
801         if (!m) {
802                 ti->error = "can't allocate multipath";
803                 return -EINVAL;
804         }
805
806         r = parse_features(&as, m);
807         if (r)
808                 goto bad;
809
810         r = parse_hw_handler(&as, m);
811         if (r)
812                 goto bad;
813
814         r = read_param(_params, shift(&as), &m->nr_priority_groups, &ti->error);
815         if (r)
816                 goto bad;
817
818         r = read_param(_params + 1, shift(&as), &next_pg_num, &ti->error);
819         if (r)
820                 goto bad;
821
822         /* parse the priority groups */
823         while (as.argc) {
824                 struct priority_group *pg;
825
826                 pg = parse_priority_group(&as, m);
827                 if (IS_ERR(pg)) {
828                         r = PTR_ERR(pg);
829                         goto bad;
830                 }
831
832                 m->nr_valid_paths += pg->nr_pgpaths;
833                 list_add_tail(&pg->list, &m->priority_groups);
834                 pg_count++;
835                 pg->pg_num = pg_count;
836                 if (!--next_pg_num)
837                         m->next_pg = pg;
838         }
839
840         if (pg_count != m->nr_priority_groups) {
841                 ti->error = "priority group count mismatch";
842                 r = -EINVAL;
843                 goto bad;
844         }
845
846         ti->num_flush_requests = 1;
847
848         return 0;
849
850  bad:
851         free_multipath(m);
852         return r;
853 }
854
855 static void multipath_dtr(struct dm_target *ti)
856 {
857         struct multipath *m = (struct multipath *) ti->private;
858
859         flush_workqueue(kmpath_handlerd);
860         flush_workqueue(kmultipathd);
861         flush_scheduled_work();
862         free_multipath(m);
863 }
864
865 /*
866  * Map bios, recording original fields for later in case we have to resubmit
867  */
868 static int multipath_map(struct dm_target *ti, struct bio *bio,
869                          union map_info *map_context)
870 {
871         int r;
872         struct dm_mpath_io *mpio;
873         struct multipath *m = (struct multipath *) ti->private;
874
875         mpio = mempool_alloc(m->mpio_pool, GFP_NOIO);
876         dm_bio_record(&mpio->details, bio);
877
878         map_context->ptr = mpio;
879         bio->bi_rw |= (1 << BIO_RW_FAILFAST_TRANSPORT);
880         r = map_io(m, bio, mpio, 0);
881         if (r < 0 || r == DM_MAPIO_REQUEUE)
882                 mempool_free(mpio, m->mpio_pool);
883
884         return r;
885 }
886
887 /*
888  * Take a path out of use.
889  */
890 static int fail_path(struct pgpath *pgpath)
891 {
892         unsigned long flags;
893         struct multipath *m = pgpath->pg->m;
894
895         spin_lock_irqsave(&m->lock, flags);
896
897         if (!pgpath->is_active)
898                 goto out;
899
900         DMWARN("Failing path %s.", pgpath->path.dev->name);
901
902         pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
903         pgpath->is_active = 0;
904         pgpath->fail_count++;
905
906         m->nr_valid_paths--;
907
908         if (pgpath == m->current_pgpath)
909                 m->current_pgpath = NULL;
910
911         dm_path_uevent(DM_UEVENT_PATH_FAILED, m->ti,
912                       pgpath->path.dev->name, m->nr_valid_paths);
913
914         schedule_work(&m->trigger_event);
915         queue_work(kmultipathd, &pgpath->deactivate_path);
916
917 out:
918         spin_unlock_irqrestore(&m->lock, flags);
919
920         return 0;
921 }
922
923 /*
924  * Reinstate a previously-failed path
925  */
926 static int reinstate_path(struct pgpath *pgpath)
927 {
928         int r = 0;
929         unsigned long flags;
930         struct multipath *m = pgpath->pg->m;
931
932         spin_lock_irqsave(&m->lock, flags);
933
934         if (pgpath->is_active)
935                 goto out;
936
937         if (!pgpath->pg->ps.type->reinstate_path) {
938                 DMWARN("Reinstate path not supported by path selector %s",
939                        pgpath->pg->ps.type->name);
940                 r = -EINVAL;
941                 goto out;
942         }
943
944         r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
945         if (r)
946                 goto out;
947
948         pgpath->is_active = 1;
949
950         if (!m->nr_valid_paths++ && m->queue_size) {
951                 m->current_pgpath = NULL;
952                 queue_work(kmultipathd, &m->process_queued_ios);
953         } else if (m->hw_handler_name && (m->current_pg == pgpath->pg)) {
954                 if (queue_work(kmpath_handlerd, &pgpath->activate_path))
955                         m->pg_init_in_progress++;
956         }
957
958         dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti,
959                       pgpath->path.dev->name, m->nr_valid_paths);
960
961         schedule_work(&m->trigger_event);
962
963 out:
964         spin_unlock_irqrestore(&m->lock, flags);
965
966         return r;
967 }
968
969 /*
970  * Fail or reinstate all paths that match the provided struct dm_dev.
971  */
972 static int action_dev(struct multipath *m, struct dm_dev *dev,
973                       action_fn action)
974 {
975         int r = 0;
976         struct pgpath *pgpath;
977         struct priority_group *pg;
978
979         list_for_each_entry(pg, &m->priority_groups, list) {
980                 list_for_each_entry(pgpath, &pg->pgpaths, list) {
981                         if (pgpath->path.dev == dev)
982                                 r = action(pgpath);
983                 }
984         }
985
986         return r;
987 }
988
989 /*
990  * Temporarily try to avoid having to use the specified PG
991  */
992 static void bypass_pg(struct multipath *m, struct priority_group *pg,
993                       int bypassed)
994 {
995         unsigned long flags;
996
997         spin_lock_irqsave(&m->lock, flags);
998
999         pg->bypassed = bypassed;
1000         m->current_pgpath = NULL;
1001         m->current_pg = NULL;
1002
1003         spin_unlock_irqrestore(&m->lock, flags);
1004
1005         schedule_work(&m->trigger_event);
1006 }
1007
1008 /*
1009  * Switch to using the specified PG from the next I/O that gets mapped
1010  */
1011 static int switch_pg_num(struct multipath *m, const char *pgstr)
1012 {
1013         struct priority_group *pg;
1014         unsigned pgnum;
1015         unsigned long flags;
1016
1017         if (!pgstr || (sscanf(pgstr, "%u", &pgnum) != 1) || !pgnum ||
1018             (pgnum > m->nr_priority_groups)) {
1019                 DMWARN("invalid PG number supplied to switch_pg_num");
1020                 return -EINVAL;
1021         }
1022
1023         spin_lock_irqsave(&m->lock, flags);
1024         list_for_each_entry(pg, &m->priority_groups, list) {
1025                 pg->bypassed = 0;
1026                 if (--pgnum)
1027                         continue;
1028
1029                 m->current_pgpath = NULL;
1030                 m->current_pg = NULL;
1031                 m->next_pg = pg;
1032         }
1033         spin_unlock_irqrestore(&m->lock, flags);
1034
1035         schedule_work(&m->trigger_event);
1036         return 0;
1037 }
1038
1039 /*
1040  * Set/clear bypassed status of a PG.
1041  * PGs are numbered upwards from 1 in the order they were declared.
1042  */
1043 static int bypass_pg_num(struct multipath *m, const char *pgstr, int bypassed)
1044 {
1045         struct priority_group *pg;
1046         unsigned pgnum;
1047
1048         if (!pgstr || (sscanf(pgstr, "%u", &pgnum) != 1) || !pgnum ||
1049             (pgnum > m->nr_priority_groups)) {
1050                 DMWARN("invalid PG number supplied to bypass_pg");
1051                 return -EINVAL;
1052         }
1053
1054         list_for_each_entry(pg, &m->priority_groups, list) {
1055                 if (!--pgnum)
1056                         break;
1057         }
1058
1059         bypass_pg(m, pg, bypassed);
1060         return 0;
1061 }
1062
1063 /*
1064  * Should we retry pg_init immediately?
1065  */
1066 static int pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath)
1067 {
1068         unsigned long flags;
1069         int limit_reached = 0;
1070
1071         spin_lock_irqsave(&m->lock, flags);
1072
1073         if (m->pg_init_count <= m->pg_init_retries)
1074                 m->pg_init_required = 1;
1075         else
1076                 limit_reached = 1;
1077
1078         spin_unlock_irqrestore(&m->lock, flags);
1079
1080         return limit_reached;
1081 }
1082
1083 static void pg_init_done(struct dm_path *path, int errors)
1084 {
1085         struct pgpath *pgpath = path_to_pgpath(path);
1086         struct priority_group *pg = pgpath->pg;
1087         struct multipath *m = pg->m;
1088         unsigned long flags;
1089
1090         /* device or driver problems */
1091         switch (errors) {
1092         case SCSI_DH_OK:
1093                 break;
1094         case SCSI_DH_NOSYS:
1095                 if (!m->hw_handler_name) {
1096                         errors = 0;
1097                         break;
1098                 }
1099                 DMERR("Cannot failover device because scsi_dh_%s was not "
1100                       "loaded.", m->hw_handler_name);
1101                 /*
1102                  * Fail path for now, so we do not ping pong
1103                  */
1104                 fail_path(pgpath);
1105                 break;
1106         case SCSI_DH_DEV_TEMP_BUSY:
1107                 /*
1108                  * Probably doing something like FW upgrade on the
1109                  * controller so try the other pg.
1110                  */
1111                 bypass_pg(m, pg, 1);
1112                 break;
1113         /* TODO: For SCSI_DH_RETRY we should wait a couple seconds */
1114         case SCSI_DH_RETRY:
1115         case SCSI_DH_IMM_RETRY:
1116         case SCSI_DH_RES_TEMP_UNAVAIL:
1117                 if (pg_init_limit_reached(m, pgpath))
1118                         fail_path(pgpath);
1119                 errors = 0;
1120                 break;
1121         default:
1122                 /*
1123                  * We probably do not want to fail the path for a device
1124                  * error, but this is what the old dm did. In future
1125                  * patches we can do more advanced handling.
1126                  */
1127                 fail_path(pgpath);
1128         }
1129
1130         spin_lock_irqsave(&m->lock, flags);
1131         if (errors) {
1132                 if (pgpath == m->current_pgpath) {
1133                         DMERR("Could not failover device. Error %d.", errors);
1134                         m->current_pgpath = NULL;
1135                         m->current_pg = NULL;
1136                 }
1137         } else if (!m->pg_init_required) {
1138                 m->queue_io = 0;
1139                 pg->bypassed = 0;
1140         }
1141
1142         m->pg_init_in_progress--;
1143         if (!m->pg_init_in_progress)
1144                 queue_work(kmultipathd, &m->process_queued_ios);
1145         spin_unlock_irqrestore(&m->lock, flags);
1146 }
1147
1148 static void activate_path(struct work_struct *work)
1149 {
1150         int ret;
1151         struct pgpath *pgpath =
1152                 container_of(work, struct pgpath, activate_path);
1153
1154         ret = scsi_dh_activate(bdev_get_queue(pgpath->path.dev->bdev));
1155         pg_init_done(&pgpath->path, ret);
1156 }
1157
1158 /*
1159  * end_io handling
1160  */
1161 static int do_end_io(struct multipath *m, struct bio *bio,
1162                      int error, struct dm_mpath_io *mpio)
1163 {
1164         unsigned long flags;
1165
1166         if (!error)
1167                 return 0;       /* I/O complete */
1168
1169         if ((error == -EWOULDBLOCK) && bio_rw_ahead(bio))
1170                 return error;
1171
1172         if (error == -EOPNOTSUPP)
1173                 return error;
1174
1175         spin_lock_irqsave(&m->lock, flags);
1176         if (!m->nr_valid_paths) {
1177                 if (__must_push_back(m)) {
1178                         spin_unlock_irqrestore(&m->lock, flags);
1179                         return DM_ENDIO_REQUEUE;
1180                 } else if (!m->queue_if_no_path) {
1181                         spin_unlock_irqrestore(&m->lock, flags);
1182                         return -EIO;
1183                 } else {
1184                         spin_unlock_irqrestore(&m->lock, flags);
1185                         goto requeue;
1186                 }
1187         }
1188         spin_unlock_irqrestore(&m->lock, flags);
1189
1190         if (mpio->pgpath)
1191                 fail_path(mpio->pgpath);
1192
1193       requeue:
1194         dm_bio_restore(&mpio->details, bio);
1195
1196         /* queue for the daemon to resubmit or fail */
1197         spin_lock_irqsave(&m->lock, flags);
1198         bio_list_add(&m->queued_ios, bio);
1199         m->queue_size++;
1200         if (!m->queue_io)
1201                 queue_work(kmultipathd, &m->process_queued_ios);
1202         spin_unlock_irqrestore(&m->lock, flags);
1203
1204         return DM_ENDIO_INCOMPLETE;     /* io not complete */
1205 }
1206
1207 static int multipath_end_io(struct dm_target *ti, struct bio *bio,
1208                             int error, union map_info *map_context)
1209 {
1210         struct multipath *m = ti->private;
1211         struct dm_mpath_io *mpio = map_context->ptr;
1212         struct pgpath *pgpath = mpio->pgpath;
1213         struct path_selector *ps;
1214         int r;
1215
1216         r  = do_end_io(m, bio, error, mpio);
1217         if (pgpath) {
1218                 ps = &pgpath->pg->ps;
1219                 if (ps->type->end_io)
1220                         ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
1221         }
1222         if (r != DM_ENDIO_INCOMPLETE)
1223                 mempool_free(mpio, m->mpio_pool);
1224
1225         return r;
1226 }
1227
1228 /*
1229  * Suspend can't complete until all the I/O is processed so if
1230  * the last path fails we must error any remaining I/O.
1231  * Note that if the freeze_bdev fails while suspending, the
1232  * queue_if_no_path state is lost - userspace should reset it.
1233  */
1234 static void multipath_presuspend(struct dm_target *ti)
1235 {
1236         struct multipath *m = (struct multipath *) ti->private;
1237
1238         queue_if_no_path(m, 0, 1);
1239 }
1240
1241 /*
1242  * Restore the queue_if_no_path setting.
1243  */
1244 static void multipath_resume(struct dm_target *ti)
1245 {
1246         struct multipath *m = (struct multipath *) ti->private;
1247         unsigned long flags;
1248
1249         spin_lock_irqsave(&m->lock, flags);
1250         m->queue_if_no_path = m->saved_queue_if_no_path;
1251         spin_unlock_irqrestore(&m->lock, flags);
1252 }
1253
1254 /*
1255  * Info output has the following format:
1256  * num_multipath_feature_args [multipath_feature_args]*
1257  * num_handler_status_args [handler_status_args]*
1258  * num_groups init_group_number
1259  *            [A|D|E num_ps_status_args [ps_status_args]*
1260  *             num_paths num_selector_args
1261  *             [path_dev A|F fail_count [selector_args]* ]+ ]+
1262  *
1263  * Table output has the following format (identical to the constructor string):
1264  * num_feature_args [features_args]*
1265  * num_handler_args hw_handler [hw_handler_args]*
1266  * num_groups init_group_number
1267  *     [priority selector-name num_ps_args [ps_args]*
1268  *      num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
1269  */
1270 static int multipath_status(struct dm_target *ti, status_type_t type,
1271                             char *result, unsigned int maxlen)
1272 {
1273         int sz = 0;
1274         unsigned long flags;
1275         struct multipath *m = (struct multipath *) ti->private;
1276         struct priority_group *pg;
1277         struct pgpath *p;
1278         unsigned pg_num;
1279         char state;
1280
1281         spin_lock_irqsave(&m->lock, flags);
1282
1283         /* Features */
1284         if (type == STATUSTYPE_INFO)
1285                 DMEMIT("2 %u %u ", m->queue_size, m->pg_init_count);
1286         else {
1287                 DMEMIT("%u ", m->queue_if_no_path +
1288                               (m->pg_init_retries > 0) * 2);
1289                 if (m->queue_if_no_path)
1290                         DMEMIT("queue_if_no_path ");
1291                 if (m->pg_init_retries)
1292                         DMEMIT("pg_init_retries %u ", m->pg_init_retries);
1293         }
1294
1295         if (!m->hw_handler_name || type == STATUSTYPE_INFO)
1296                 DMEMIT("0 ");
1297         else
1298                 DMEMIT("1 %s ", m->hw_handler_name);
1299
1300         DMEMIT("%u ", m->nr_priority_groups);
1301
1302         if (m->next_pg)
1303                 pg_num = m->next_pg->pg_num;
1304         else if (m->current_pg)
1305                 pg_num = m->current_pg->pg_num;
1306         else
1307                         pg_num = 1;
1308
1309         DMEMIT("%u ", pg_num);
1310
1311         switch (type) {
1312         case STATUSTYPE_INFO:
1313                 list_for_each_entry(pg, &m->priority_groups, list) {
1314                         if (pg->bypassed)
1315                                 state = 'D';    /* Disabled */
1316                         else if (pg == m->current_pg)
1317                                 state = 'A';    /* Currently Active */
1318                         else
1319                                 state = 'E';    /* Enabled */
1320
1321                         DMEMIT("%c ", state);
1322
1323                         if (pg->ps.type->status)
1324                                 sz += pg->ps.type->status(&pg->ps, NULL, type,
1325                                                           result + sz,
1326                                                           maxlen - sz);
1327                         else
1328                                 DMEMIT("0 ");
1329
1330                         DMEMIT("%u %u ", pg->nr_pgpaths,
1331                                pg->ps.type->info_args);
1332
1333                         list_for_each_entry(p, &pg->pgpaths, list) {
1334                                 DMEMIT("%s %s %u ", p->path.dev->name,
1335                                        p->is_active ? "A" : "F",
1336                                        p->fail_count);
1337                                 if (pg->ps.type->status)
1338                                         sz += pg->ps.type->status(&pg->ps,
1339                                               &p->path, type, result + sz,
1340                                               maxlen - sz);
1341                         }
1342                 }
1343                 break;
1344
1345         case STATUSTYPE_TABLE:
1346                 list_for_each_entry(pg, &m->priority_groups, list) {
1347                         DMEMIT("%s ", pg->ps.type->name);
1348
1349                         if (pg->ps.type->status)
1350                                 sz += pg->ps.type->status(&pg->ps, NULL, type,
1351                                                           result + sz,
1352                                                           maxlen - sz);
1353                         else
1354                                 DMEMIT("0 ");
1355
1356                         DMEMIT("%u %u ", pg->nr_pgpaths,
1357                                pg->ps.type->table_args);
1358
1359                         list_for_each_entry(p, &pg->pgpaths, list) {
1360                                 DMEMIT("%s ", p->path.dev->name);
1361                                 if (pg->ps.type->status)
1362                                         sz += pg->ps.type->status(&pg->ps,
1363                                               &p->path, type, result + sz,
1364                                               maxlen - sz);
1365                         }
1366                 }
1367                 break;
1368         }
1369
1370         spin_unlock_irqrestore(&m->lock, flags);
1371
1372         return 0;
1373 }
1374
1375 static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
1376 {
1377         int r;
1378         struct dm_dev *dev;
1379         struct multipath *m = (struct multipath *) ti->private;
1380         action_fn action;
1381
1382         if (argc == 1) {
1383                 if (!strnicmp(argv[0], MESG_STR("queue_if_no_path")))
1384                         return queue_if_no_path(m, 1, 0);
1385                 else if (!strnicmp(argv[0], MESG_STR("fail_if_no_path")))
1386                         return queue_if_no_path(m, 0, 0);
1387         }
1388
1389         if (argc != 2)
1390                 goto error;
1391
1392         if (!strnicmp(argv[0], MESG_STR("disable_group")))
1393                 return bypass_pg_num(m, argv[1], 1);
1394         else if (!strnicmp(argv[0], MESG_STR("enable_group")))
1395                 return bypass_pg_num(m, argv[1], 0);
1396         else if (!strnicmp(argv[0], MESG_STR("switch_group")))
1397                 return switch_pg_num(m, argv[1]);
1398         else if (!strnicmp(argv[0], MESG_STR("reinstate_path")))
1399                 action = reinstate_path;
1400         else if (!strnicmp(argv[0], MESG_STR("fail_path")))
1401                 action = fail_path;
1402         else
1403                 goto error;
1404
1405         r = dm_get_device(ti, argv[1], ti->begin, ti->len,
1406                           dm_table_get_mode(ti->table), &dev);
1407         if (r) {
1408                 DMWARN("message: error getting device %s",
1409                        argv[1]);
1410                 return -EINVAL;
1411         }
1412
1413         r = action_dev(m, dev, action);
1414
1415         dm_put_device(ti, dev);
1416
1417         return r;
1418
1419 error:
1420         DMWARN("Unrecognised multipath message received.");
1421         return -EINVAL;
1422 }
1423
1424 static int multipath_ioctl(struct dm_target *ti, unsigned int cmd,
1425                            unsigned long arg)
1426 {
1427         struct multipath *m = (struct multipath *) ti->private;
1428         struct block_device *bdev = NULL;
1429         fmode_t mode = 0;
1430         unsigned long flags;
1431         int r = 0;
1432
1433         spin_lock_irqsave(&m->lock, flags);
1434
1435         if (!m->current_pgpath)
1436                 __choose_pgpath(m, 0);
1437
1438         if (m->current_pgpath) {
1439                 bdev = m->current_pgpath->path.dev->bdev;
1440                 mode = m->current_pgpath->path.dev->mode;
1441         }
1442
1443         if (m->queue_io)
1444                 r = -EAGAIN;
1445         else if (!bdev)
1446                 r = -EIO;
1447
1448         spin_unlock_irqrestore(&m->lock, flags);
1449
1450         return r ? : __blkdev_driver_ioctl(bdev, mode, cmd, arg);
1451 }
1452
1453 static int multipath_iterate_devices(struct dm_target *ti,
1454                                      iterate_devices_callout_fn fn, void *data)
1455 {
1456         struct multipath *m = ti->private;
1457         struct priority_group *pg;
1458         struct pgpath *p;
1459         int ret = 0;
1460
1461         list_for_each_entry(pg, &m->priority_groups, list) {
1462                 list_for_each_entry(p, &pg->pgpaths, list) {
1463                         ret = fn(ti, p->path.dev, ti->begin, data);
1464                         if (ret)
1465                                 goto out;
1466                 }
1467         }
1468
1469 out:
1470         return ret;
1471 }
1472
1473 /*-----------------------------------------------------------------
1474  * Module setup
1475  *---------------------------------------------------------------*/
1476 static struct target_type multipath_target = {
1477         .name = "multipath",
1478         .version = {1, 1, 0},
1479         .module = THIS_MODULE,
1480         .ctr = multipath_ctr,
1481         .dtr = multipath_dtr,
1482         .map = multipath_map,
1483         .end_io = multipath_end_io,
1484         .presuspend = multipath_presuspend,
1485         .resume = multipath_resume,
1486         .status = multipath_status,
1487         .message = multipath_message,
1488         .ioctl  = multipath_ioctl,
1489         .iterate_devices = multipath_iterate_devices,
1490 };
1491
1492 static int __init dm_multipath_init(void)
1493 {
1494         int r;
1495
1496         /* allocate a slab for the dm_ios */
1497         _mpio_cache = KMEM_CACHE(dm_mpath_io, 0);
1498         if (!_mpio_cache)
1499                 return -ENOMEM;
1500
1501         r = dm_register_target(&multipath_target);
1502         if (r < 0) {
1503                 DMERR("register failed %d", r);
1504                 kmem_cache_destroy(_mpio_cache);
1505                 return -EINVAL;
1506         }
1507
1508         kmultipathd = create_workqueue("kmpathd");
1509         if (!kmultipathd) {
1510                 DMERR("failed to create workqueue kmpathd");
1511                 dm_unregister_target(&multipath_target);
1512                 kmem_cache_destroy(_mpio_cache);
1513                 return -ENOMEM;
1514         }
1515
1516         /*
1517          * A separate workqueue is used to handle the device handlers
1518          * to avoid overloading existing workqueue. Overloading the
1519          * old workqueue would also create a bottleneck in the
1520          * path of the storage hardware device activation.
1521          */
1522         kmpath_handlerd = create_singlethread_workqueue("kmpath_handlerd");
1523         if (!kmpath_handlerd) {
1524                 DMERR("failed to create workqueue kmpath_handlerd");
1525                 destroy_workqueue(kmultipathd);
1526                 dm_unregister_target(&multipath_target);
1527                 kmem_cache_destroy(_mpio_cache);
1528                 return -ENOMEM;
1529         }
1530
1531         DMINFO("version %u.%u.%u loaded",
1532                multipath_target.version[0], multipath_target.version[1],
1533                multipath_target.version[2]);
1534
1535         return r;
1536 }
1537
1538 static void __exit dm_multipath_exit(void)
1539 {
1540         destroy_workqueue(kmpath_handlerd);
1541         destroy_workqueue(kmultipathd);
1542
1543         dm_unregister_target(&multipath_target);
1544         kmem_cache_destroy(_mpio_cache);
1545 }
1546
1547 module_init(dm_multipath_init);
1548 module_exit(dm_multipath_exit);
1549
1550 MODULE_DESCRIPTION(DM_NAME " multipath target");
1551 MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
1552 MODULE_LICENSE("GPL");