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 "dm.h"
   9 #include "dm-path-selector.h"
  10 #include "dm-hw-handler.h"
  11 #include "dm-bio-list.h"
  12 #include "dm-bio-record.h"
  13 #include "dm-uevent.h"
  14
  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 <scsi/scsi_dh.h>
  24 #include <asm/atomic.h>
  25
  26 #define DM_MSG_PREFIX "multipath"
  27 #define MESG_STR(x) x, sizeof(x)
  28
  29 /* Path properties */
  30 struct pgpath {
  31         struct list_head list;
  32
  33         struct priority_group *pg;      /* Owning PG */
  34         unsigned fail_count;            /* Cumulative failure count */
  35
  36         struct dm_path path;
  37 };
  38
  39 #define path_to_pgpath(__pgp) container_of((__pgp), struct pgpath, path)
  40
  41 /*
  42  * Paths are grouped into Priority Groups and numbered from 1 upwards.
  43  * Each has a path selector which controls which path gets used.
  44  */
  45 struct priority_group {
  46         struct list_head list;
  47
  48         struct multipath *m;            /* Owning multipath instance */
  49         struct path_selector ps;
  50
  51         unsigned pg_num;                /* Reference number */
  52         unsigned bypassed;              /* Temporarily bypass this PG? */
  53
  54         unsigned nr_pgpaths;            /* Number of paths in PG */
  55         struct list_head pgpaths;
  56 };
  57
  58 /* Multipath context */
  59 struct multipath {
  60         struct list_head list;
  61         struct dm_target *ti;
  62
  63         spinlock_t lock;
  64
  65         const char *hw_handler_name;
  66         struct work_struct activate_path;
  67         unsigned nr_priority_groups;
  68         struct list_head priority_groups;
  69         unsigned pg_init_required;      /* pg_init needs calling? */
  70         unsigned pg_init_in_progress;   /* Only one pg_init allowed at once */
  71
  72         unsigned nr_valid_paths;        /* Total number of usable paths */
  73         struct pgpath *current_pgpath;
  74         struct priority_group *current_pg;
  75         struct priority_group *next_pg; /* Switch to this PG if set */
  76         unsigned repeat_count;          /* I/Os left before calling PS again */
  77
  78         unsigned queue_io;              /* Must we queue all I/O? */
  79         unsigned queue_if_no_path;      /* Queue I/O if last path fails? */
  80         unsigned saved_queue_if_no_path;/* Saved state during suspension */
  81         unsigned pg_init_retries;       /* Number of times to retry pg_init */
  82         unsigned pg_init_count;         /* Number of times pg_init called */
  83
  84         struct work_struct process_queued_ios;
  85         struct bio_list queued_ios;
  86         unsigned queue_size;
  87
  88         struct work_struct trigger_event;
  89
  90         /*
  91          * We must use a mempool of dm_mpath_io structs so that we
  92          * can resubmit bios on error.
  93          */
  94         mempool_t *mpio_pool;
  95 };
  96
  97 /*
  98  * Context information attached to each bio we process.
  99  */
 100 struct dm_mpath_io {
 101         struct pgpath *pgpath;
 102         struct dm_bio_details details;
 103 };
 104
 105 typedef int (*action_fn) (struct pgpath *pgpath);
 106
 107 #define MIN_IOS 256     /* Mempool size */
 108
 109 static struct kmem_cache *_mpio_cache;
 110
 111 static struct workqueue_struct *kmultipathd, *kmpath_handlerd;
 112 static void process_queued_ios(struct work_struct *work);
 113 static void trigger_event(struct work_struct *work);
 114 static void activate_path(struct work_struct *work);
 115
 116
 117 /*-----------------------------------------------
 118  * Allocation routines
 119  *-----------------------------------------------*/
 120
 121 static struct pgpath *alloc_pgpath(void)
 122 {
 123         struct pgpath *pgpath = kzalloc(sizeof(*pgpath), GFP_KERNEL);
 124
 125         if (pgpath)
 126                 pgpath->path.is_active = 1;
 127
 128         return pgpath;
 129 }
 130
 131 static void free_pgpath(struct pgpath *pgpath)
 132 {
 133         kfree(pgpath);
 134 }
 135
 136 static struct priority_group *alloc_priority_group(void)
 137 {
 138         struct priority_group *pg;
 139
 140         pg = kzalloc(sizeof(*pg), GFP_KERNEL);
 141
 142         if (pg)
 143                 INIT_LIST_HEAD(&pg->pgpaths);
 144
 145         return pg;
 146 }
 147
 148 static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti)
 149 {
 150         struct pgpath *pgpath, *tmp;
 151
 152         list_for_each_entry_safe(pgpath, tmp, pgpaths, list) {
 153                 list_del(&pgpath->list);
 154                 dm_put_device(ti, pgpath->path.dev);
 155                 free_pgpath(pgpath);
 156         }
 157 }
 158
 159 static void free_priority_group(struct priority_group *pg,
 160                                 struct dm_target *ti)
 161 {
 162         struct path_selector *ps = &pg->ps;
 163
 164         if (ps->type) {
 165                 ps->type->destroy(ps);
 166                 dm_put_path_selector(ps->type);
 167         }
 168
 169         free_pgpaths(&pg->pgpaths, ti);
 170         kfree(pg);
 171 }
 172
 173 static struct multipath *alloc_multipath(struct dm_target *ti)
 174 {
 175         struct multipath *m;
 176
 177         m = kzalloc(sizeof(*m), GFP_KERNEL);
 178         if (m) {
 179                 INIT_LIST_HEAD(&m->priority_groups);
 180                 spin_lock_init(&m->lock);
 181                 m->queue_io = 1;
 182                 INIT_WORK(&m->process_queued_ios, process_queued_ios);
 183                 INIT_WORK(&m->trigger_event, trigger_event);
 184                 INIT_WORK(&m->activate_path, activate_path);
 185                 m->mpio_pool = mempool_create_slab_pool(MIN_IOS, _mpio_cache);
 186                 if (!m->mpio_pool) {
 187                         kfree(m);
 188                         return NULL;
 189                 }
 190                 m->ti = ti;
 191                 ti->private = m;
 192         }
 193
 194         return m;
 195 }
 196
 197 static void free_multipath(struct multipath *m)
 198 {
 199         struct priority_group *pg, *tmp;
 200
 201         list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) {
 202                 list_del(&pg->list);
 203                 free_priority_group(pg, m->ti);
 204         }
 205
 206         kfree(m->hw_handler_name);
 207         mempool_destroy(m->mpio_pool);
 208         kfree(m);
 209 }
 210
 211
 212 /*-----------------------------------------------
 213  * Path selection
 214  *-----------------------------------------------*/
 215
 216 static void __switch_pg(struct multipath *m, struct pgpath *pgpath)
 217 {
 218         m->current_pg = pgpath->pg;
 219
 220         /* Must we initialise the PG first, and queue I/O till it's ready? */
 221         if (m->hw_handler_name) {
 222                 m->pg_init_required = 1;
 223                 m->queue_io = 1;
 224         } else {
 225                 m->pg_init_required = 0;
 226                 m->queue_io = 0;
 227         }
 228
 229         m->pg_init_count = 0;
 230 }
 231
 232 static int __choose_path_in_pg(struct multipath *m, struct priority_group *pg)
 233 {
 234         struct dm_path *path;
 235
 236         path = pg->ps.type->select_path(&pg->ps, &m->repeat_count);
 237         if (!path)
 238                 return -ENXIO;
 239
 240         m->current_pgpath = path_to_pgpath(path);
 241
 242         if (m->current_pg != pg)
 243                 __switch_pg(m, m->current_pgpath);
 244
 245         return 0;
 246 }
 247
 248 static void __choose_pgpath(struct multipath *m)
 249 {
 250         struct priority_group *pg;
 251         unsigned bypassed = 1;
 252
 253         if (!m->nr_valid_paths)
 254                 goto failed;
 255
 256         /* Were we instructed to switch PG? */
 257         if (m->next_pg) {
 258                 pg = m->next_pg;
 259                 m->next_pg = NULL;
 260                 if (!__choose_path_in_pg(m, pg))
 261                         return;
 262         }
 263
 264         /* Don't change PG until it has no remaining paths */
 265         if (m->current_pg && !__choose_path_in_pg(m, m->current_pg))
 266                 return;
 267
 268         /*
 269          * Loop through priority groups until we find a valid path.
 270          * First time we skip PGs marked 'bypassed'.
 271          * Second time we only try the ones we skipped.
 272          */
 273         do {
 274                 list_for_each_entry(pg, &m->priority_groups, list) {
 275                         if (pg->bypassed == bypassed)
 276                                 continue;
 277                         if (!__choose_path_in_pg(m, pg))
 278                                 return;
 279                 }
 280         } while (bypassed--);
 281
 282 failed:
 283         m->current_pgpath = NULL;
 284         m->current_pg = NULL;
 285 }
 286
 287 /*
 288  * Check whether bios must be queued in the device-mapper core rather
 289  * than here in the target.
 290  *
 291  * m->lock must be held on entry.
 292  *
 293  * If m->queue_if_no_path and m->saved_queue_if_no_path hold the
 294  * same value then we are not between multipath_presuspend()
 295  * and multipath_resume() calls and we have no need to check
 296  * for the DMF_NOFLUSH_SUSPENDING flag.
 297  */
 298 static int __must_push_back(struct multipath *m)
 299 {
 300         return (m->queue_if_no_path != m->saved_queue_if_no_path &&
 301                 dm_noflush_suspending(m->ti));
 302 }
 303
 304 static int map_io(struct multipath *m, struct bio *bio,
 305                   struct dm_mpath_io *mpio, unsigned was_queued)
 306 {
 307         int r = DM_MAPIO_REMAPPED;
 308         unsigned long flags;
 309         struct pgpath *pgpath;
 310
 311         spin_lock_irqsave(&m->lock, flags);
 312
 313         /* Do we need to select a new pgpath? */
 314         if (!m->current_pgpath ||
 315             (!m->queue_io && (m->repeat_count && --m->repeat_count == 0)))
 316                 __choose_pgpath(m);
 317
 318         pgpath = m->current_pgpath;
 319
 320         if (was_queued)
 321                 m->queue_size--;
 322
 323         if ((pgpath && m->queue_io) ||
 324             (!pgpath && m->queue_if_no_path)) {
 325                 /* Queue for the daemon to resubmit */
 326                 bio_list_add(&m->queued_ios, bio);
 327                 m->queue_size++;
 328                 if ((m->pg_init_required && !m->pg_init_in_progress) ||
 329                     !m->queue_io)
 330                         queue_work(kmultipathd, &m->process_queued_ios);
 331                 pgpath = NULL;
 332                 r = DM_MAPIO_SUBMITTED;
 333         } else if (pgpath)
 334                 bio->bi_bdev = pgpath->path.dev->bdev;
 335         else if (__must_push_back(m))
 336                 r = DM_MAPIO_REQUEUE;
 337         else
 338                 r = -EIO;       /* Failed */
 339
 340         mpio->pgpath = pgpath;
 341
 342         spin_unlock_irqrestore(&m->lock, flags);
 343
 344         return r;
 345 }
 346
 347 /*
 348  * If we run out of usable paths, should we queue I/O or error it?
 349  */
 350 static int queue_if_no_path(struct multipath *m, unsigned queue_if_no_path,
 351                             unsigned save_old_value)
 352 {
 353         unsigned long flags;
 354
 355         spin_lock_irqsave(&m->lock, flags);
 356
 357         if (save_old_value)
 358                 m->saved_queue_if_no_path = m->queue_if_no_path;
 359         else
 360                 m->saved_queue_if_no_path = queue_if_no_path;
 361         m->queue_if_no_path = queue_if_no_path;
 362         if (!m->queue_if_no_path && m->queue_size)
 363                 queue_work(kmultipathd, &m->process_queued_ios);
 364
 365         spin_unlock_irqrestore(&m->lock, flags);
 366
 367         return 0;
 368 }
 369
 370 /*-----------------------------------------------------------------
 371  * The multipath daemon is responsible for resubmitting queued ios.
 372  *---------------------------------------------------------------*/
 373
 374 static void dispatch_queued_ios(struct multipath *m)
 375 {
 376         int r;
 377         unsigned long flags;
 378         struct bio *bio = NULL, *next;
 379         struct dm_mpath_io *mpio;
 380         union map_info *info;
 381
 382         spin_lock_irqsave(&m->lock, flags);
 383         bio = bio_list_get(&m->queued_ios);
 384         spin_unlock_irqrestore(&m->lock, flags);
 385
 386         while (bio) {
 387                 next = bio->bi_next;
 388                 bio->bi_next = NULL;
 389
 390                 info = dm_get_mapinfo(bio);
 391                 mpio = info->ptr;
 392
 393                 r = map_io(m, bio, mpio, 1);
 394                 if (r < 0)
 395                         bio_endio(bio, r);
 396                 else if (r == DM_MAPIO_REMAPPED)
 397                         generic_make_request(bio);
 398                 else if (r == DM_MAPIO_REQUEUE)
 399                         bio_endio(bio, -EIO);
 400
 401                 bio = next;
 402         }
 403 }
 404
 405 static void process_queued_ios(struct work_struct *work)
 406 {
 407         struct multipath *m =
 408                 container_of(work, struct multipath, process_queued_ios);
 409         struct pgpath *pgpath = NULL;
 410         unsigned init_required = 0, must_queue = 1;
 411         unsigned long flags;
 412
 413         spin_lock_irqsave(&m->lock, flags);
 414
 415         if (!m->queue_size)
 416                 goto out;
 417
 418         if (!m->current_pgpath)
 419                 __choose_pgpath(m);
 420
 421         pgpath = m->current_pgpath;
 422
 423         if ((pgpath && !m->queue_io) ||
 424             (!pgpath && !m->queue_if_no_path))
 425                 must_queue = 0;
 426
 427         if (m->pg_init_required && !m->pg_init_in_progress) {
 428                 m->pg_init_count++;
 429                 m->pg_init_required = 0;
 430                 m->pg_init_in_progress = 1;
 431                 init_required = 1;
 432         }
 433
 434 out:
 435         spin_unlock_irqrestore(&m->lock, flags);
 436
 437         if (init_required)
 438                 queue_work(kmpath_handlerd, &m->activate_path);
 439
 440         if (!must_queue)
 441                 dispatch_queued_ios(m);
 442 }
 443
 444 /*
 445  * An event is triggered whenever a path is taken out of use.
 446  * Includes path failure and PG bypass.
 447  */
 448 static void trigger_event(struct work_struct *work)
 449 {
 450         struct multipath *m =
 451                 container_of(work, struct multipath, trigger_event);
 452
 453         dm_table_event(m->ti->table);
 454 }
 455
 456 /*-----------------------------------------------------------------
 457  * Constructor/argument parsing:
 458  * <#multipath feature args> [<arg>]*
 459  * <#hw_handler args> [hw_handler [<arg>]*]
 460  * <#priority groups>
 461  * <initial priority group>
 462  *     [<selector> <#selector args> [<arg>]*
 463  *      <#paths> <#per-path selector args>
 464  *         [<path> [<arg>]* ]+ ]+
 465  *---------------------------------------------------------------*/
 466 struct param {
 467         unsigned min;
 468         unsigned max;
 469         char *error;
 470 };
 471
 472 static int read_param(struct param *param, char *str, unsigned *v, char **error)
 473 {
 474         if (!str ||
 475             (sscanf(str, "%u", v) != 1) ||
 476             (*v < param->min) ||
 477             (*v > param->max)) {
 478                 *error = param->error;
 479                 return -EINVAL;
 480         }
 481
 482         return 0;
 483 }
 484
 485 struct arg_set {
 486         unsigned argc;
 487         char **argv;
 488 };
 489
 490 static char *shift(struct arg_set *as)
 491 {
 492         char *r;
 493
 494         if (as->argc) {
 495                 as->argc--;
 496                 r = *as->argv;
 497                 as->argv++;
 498                 return r;
 499         }
 500
 501         return NULL;
 502 }
 503
 504 static void consume(struct arg_set *as, unsigned n)
 505 {
 506         BUG_ON (as->argc < n);
 507         as->argc -= n;
 508         as->argv += n;
 509 }
 510
 511 static int parse_path_selector(struct arg_set *as, struct priority_group *pg,
 512                                struct dm_target *ti)
 513 {
 514         int r;
 515         struct path_selector_type *pst;
 516         unsigned ps_argc;
 517
 518         static struct param _params[] = {
 519                 {0, 1024, "invalid number of path selector args"},
 520         };
 521
 522         pst = dm_get_path_selector(shift(as));
 523         if (!pst) {
 524                 ti->error = "unknown path selector type";
 525                 return -EINVAL;
 526         }
 527
 528         r = read_param(_params, shift(as), &ps_argc, &ti->error);
 529         if (r)
 530                 return -EINVAL;
 531
 532         r = pst->create(&pg->ps, ps_argc, as->argv);
 533         if (r) {
 534                 dm_put_path_selector(pst);
 535                 ti->error = "path selector constructor failed";
 536                 return r;
 537         }
 538
 539         pg->ps.type = pst;
 540         consume(as, ps_argc);
 541
 542         return 0;
 543 }
 544
 545 static struct pgpath *parse_path(struct arg_set *as, struct path_selector *ps,
 546                                struct dm_target *ti)
 547 {
 548         int r;
 549         struct pgpath *p;
 550
 551         /* we need at least a path arg */
 552         if (as->argc < 1) {
 553                 ti->error = "no device given";
 554                 return NULL;
 555         }
 556
 557         p = alloc_pgpath();
 558         if (!p)
 559                 return NULL;
 560
 561         r = dm_get_device(ti, shift(as), ti->begin, ti->len,
 562                           dm_table_get_mode(ti->table), &p->path.dev);
 563         if (r) {
 564                 ti->error = "error getting device";
 565                 goto bad;
 566         }
 567
 568         r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
 569         if (r) {
 570                 dm_put_device(ti, p->path.dev);
 571                 goto bad;
 572         }
 573
 574         return p;
 575
 576  bad:
 577         free_pgpath(p);
 578         return NULL;
 579 }
 580
 581 static struct priority_group *parse_priority_group(struct arg_set *as,
 582                                                    struct multipath *m)
 583 {
 584         static struct param _params[] = {
 585                 {1, 1024, "invalid number of paths"},
 586                 {0, 1024, "invalid number of selector args"}
 587         };
 588
 589         int r;
 590         unsigned i, nr_selector_args, nr_params;
 591         struct priority_group *pg;
 592         struct dm_target *ti = m->ti;
 593
 594         if (as->argc < 2) {
 595                 as->argc = 0;
 596                 ti->error = "not enough priority group aruments";
 597                 return NULL;
 598         }
 599
 600         pg = alloc_priority_group();
 601         if (!pg) {
 602                 ti->error = "couldn't allocate priority group";
 603                 return NULL;
 604         }
 605         pg->m = m;
 606
 607         r = parse_path_selector(as, pg, ti);
 608         if (r)
 609                 goto bad;
 610
 611         /*
 612          * read the paths
 613          */
 614         r = read_param(_params, shift(as), &pg->nr_pgpaths, &ti->error);
 615         if (r)
 616                 goto bad;
 617
 618         r = read_param(_params + 1, shift(as), &nr_selector_args, &ti->error);
 619         if (r)
 620                 goto bad;
 621
 622         nr_params = 1 + nr_selector_args;
 623         for (i = 0; i < pg->nr_pgpaths; i++) {
 624                 struct pgpath *pgpath;
 625                 struct arg_set path_args;
 626
 627                 if (as->argc < nr_params)
 628                         goto bad;
 629
 630                 path_args.argc = nr_params;
 631                 path_args.argv = as->argv;
 632
 633                 pgpath = parse_path(&path_args, &pg->ps, ti);
 634                 if (!pgpath)
 635                         goto bad;
 636
 637                 pgpath->pg = pg;
 638                 list_add_tail(&pgpath->list, &pg->pgpaths);
 639                 consume(as, nr_params);
 640         }
 641
 642         return pg;
 643
 644  bad:
 645         free_priority_group(pg, ti);
 646         return NULL;
 647 }
 648
 649 static int parse_hw_handler(struct arg_set *as, struct multipath *m)
 650 {
 651         unsigned hw_argc;
 652         struct dm_target *ti = m->ti;
 653
 654         static struct param _params[] = {
 655                 {0, 1024, "invalid number of hardware handler args"},
 656         };
 657
 658         if (read_param(_params, shift(as), &hw_argc, &ti->error))
 659                 return -EINVAL;
 660
 661         if (!hw_argc)
 662                 return 0;
 663
 664         m->hw_handler_name = kstrdup(shift(as), GFP_KERNEL);
 665         request_module("scsi_dh_%s", m->hw_handler_name);
 666         if (scsi_dh_handler_exist(m->hw_handler_name) == 0) {
 667                 ti->error = "unknown hardware handler type";
 668                 return -EINVAL;
 669         }
 670         consume(as, hw_argc - 1);
 671
 672         return 0;
 673 }
 674
 675 static int parse_features(struct arg_set *as, struct multipath *m)
 676 {
 677         int r;
 678         unsigned argc;
 679         struct dm_target *ti = m->ti;
 680         const char *param_name;
 681
 682         static struct param _params[] = {
 683                 {0, 3, "invalid number of feature args"},
 684                 {1, 50, "pg_init_retries must be between 1 and 50"},
 685         };
 686
 687         r = read_param(_params, shift(as), &argc, &ti->error);
 688         if (r)
 689                 return -EINVAL;
 690
 691         if (!argc)
 692                 return 0;
 693
 694         do {
 695                 param_name = shift(as);
 696                 argc--;
 697
 698                 if (!strnicmp(param_name, MESG_STR("queue_if_no_path"))) {
 699                         r = queue_if_no_path(m, 1, 0);
 700                         continue;
 701                 }
 702
 703                 if (!strnicmp(param_name, MESG_STR("pg_init_retries")) &&
 704                     (argc >= 1)) {
 705                         r = read_param(_params + 1, shift(as),
 706                                        &m->pg_init_retries, &ti->error);
 707                         argc--;
 708                         continue;
 709                 }
 710
 711                 ti->error = "Unrecognised multipath feature request";
 712                 r = -EINVAL;
 713         } while (argc && !r);
 714
 715         return r;
 716 }
 717
 718 static int multipath_ctr(struct dm_target *ti, unsigned int argc,
 719                          char **argv)
 720 {
 721         /* target parameters */
 722         static struct param _params[] = {
 723                 {1, 1024, "invalid number of priority groups"},
 724                 {1, 1024, "invalid initial priority group number"},
 725         };
 726
 727         int r;
 728         struct multipath *m;
 729         struct arg_set as;
 730         unsigned pg_count = 0;
 731         unsigned next_pg_num;
 732
 733         as.argc = argc;
 734         as.argv = argv;
 735
 736         m = alloc_multipath(ti);
 737         if (!m) {
 738                 ti->error = "can't allocate multipath";
 739                 return -EINVAL;
 740         }
 741
 742         r = parse_features(&as, m);
 743         if (r)
 744                 goto bad;
 745
 746         r = parse_hw_handler(&as, m);
 747         if (r)
 748                 goto bad;
 749
 750         r = read_param(_params, shift(&as), &m->nr_priority_groups, &ti->error);
 751         if (r)
 752                 goto bad;
 753
 754         r = read_param(_params + 1, shift(&as), &next_pg_num, &ti->error);
 755         if (r)
 756                 goto bad;
 757
 758         /* parse the priority groups */
 759         while (as.argc) {
 760                 struct priority_group *pg;
 761
 762                 pg = parse_priority_group(&as, m);
 763                 if (!pg) {
 764                         r = -EINVAL;
 765                         goto bad;
 766                 }
 767
 768                 m->nr_valid_paths += pg->nr_pgpaths;
 769                 list_add_tail(&pg->list, &m->priority_groups);
 770                 pg_count++;
 771                 pg->pg_num = pg_count;
 772                 if (!--next_pg_num)
 773                         m->next_pg = pg;
 774         }
 775
 776         if (pg_count != m->nr_priority_groups) {
 777                 ti->error = "priority group count mismatch";
 778                 r = -EINVAL;
 779                 goto bad;
 780         }
 781
 782         return 0;
 783
 784  bad:
 785         free_multipath(m);
 786         return r;
 787 }
 788
 789 static void multipath_dtr(struct dm_target *ti)
 790 {
 791         struct multipath *m = (struct multipath *) ti->private;
 792
 793         flush_workqueue(kmpath_handlerd);
 794         flush_workqueue(kmultipathd);
 795         free_multipath(m);
 796 }
 797
 798 /*
 799  * Map bios, recording original fields for later in case we have to resubmit
 800  */
 801 static int multipath_map(struct dm_target *ti, struct bio *bio,
 802                          union map_info *map_context)
 803 {
 804         int r;
 805         struct dm_mpath_io *mpio;
 806         struct multipath *m = (struct multipath *) ti->private;
 807
 808         mpio = mempool_alloc(m->mpio_pool, GFP_NOIO);
 809         dm_bio_record(&mpio->details, bio);
 810
 811         map_context->ptr = mpio;
 812         bio->bi_rw |= (1 << BIO_RW_FAILFAST);
 813         r = map_io(m, bio, mpio, 0);
 814         if (r < 0 || r == DM_MAPIO_REQUEUE)
 815                 mempool_free(mpio, m->mpio_pool);
 816
 817         return r;
 818 }
 819
 820 /*
 821  * Take a path out of use.
 822  */
 823 static int fail_path(struct pgpath *pgpath)
 824 {
 825         unsigned long flags;
 826         struct multipath *m = pgpath->pg->m;
 827
 828         spin_lock_irqsave(&m->lock, flags);
 829
 830         if (!pgpath->path.is_active)
 831                 goto out;
 832
 833         DMWARN("Failing path %s.", pgpath->path.dev->name);
 834
 835         pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
 836         pgpath->path.is_active = 0;
 837         pgpath->fail_count++;
 838
 839         m->nr_valid_paths--;
 840
 841         if (pgpath == m->current_pgpath)
 842                 m->current_pgpath = NULL;
 843
 844         dm_path_uevent(DM_UEVENT_PATH_FAILED, m->ti,
 845                       pgpath->path.dev->name, m->nr_valid_paths);
 846
 847         queue_work(kmultipathd, &m->trigger_event);
 848
 849 out:
 850         spin_unlock_irqrestore(&m->lock, flags);
 851
 852         return 0;
 853 }
 854
 855 /*
 856  * Reinstate a previously-failed path
 857  */
 858 static int reinstate_path(struct pgpath *pgpath)
 859 {
 860         int r = 0;
 861         unsigned long flags;
 862         struct multipath *m = pgpath->pg->m;
 863
 864         spin_lock_irqsave(&m->lock, flags);
 865
 866         if (pgpath->path.is_active)
 867                 goto out;
 868
 869         if (!pgpath->pg->ps.type) {
 870                 DMWARN("Reinstate path not supported by path selector %s",
 871                        pgpath->pg->ps.type->name);
 872                 r = -EINVAL;
 873                 goto out;
 874         }
 875
 876         r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
 877         if (r)
 878                 goto out;
 879
 880         pgpath->path.is_active = 1;
 881
 882         m->current_pgpath = NULL;
 883         if (!m->nr_valid_paths++ && m->queue_size)
 884                 queue_work(kmultipathd, &m->process_queued_ios);
 885
 886         dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti,
 887                       pgpath->path.dev->name, m->nr_valid_paths);
 888
 889         queue_work(kmultipathd, &m->trigger_event);
 890
 891 out:
 892         spin_unlock_irqrestore(&m->lock, flags);
 893
 894         return r;
 895 }
 896
 897 /*
 898  * Fail or reinstate all paths that match the provided struct dm_dev.
 899  */
 900 static int action_dev(struct multipath *m, struct dm_dev *dev,
 901                       action_fn action)
 902 {
 903         int r = 0;
 904         struct pgpath *pgpath;
 905         struct priority_group *pg;
 906
 907         list_for_each_entry(pg, &m->priority_groups, list) {
 908                 list_for_each_entry(pgpath, &pg->pgpaths, list) {
 909                         if (pgpath->path.dev == dev)
 910                                 r = action(pgpath);
 911                 }
 912         }
 913
 914         return r;
 915 }
 916
 917 /*
 918  * Temporarily try to avoid having to use the specified PG
 919  */
 920 static void bypass_pg(struct multipath *m, struct priority_group *pg,
 921                       int bypassed)
 922 {
 923         unsigned long flags;
 924
 925         spin_lock_irqsave(&m->lock, flags);
 926
 927         pg->bypassed = bypassed;
 928         m->current_pgpath = NULL;
 929         m->current_pg = NULL;
 930
 931         spin_unlock_irqrestore(&m->lock, flags);
 932
 933         queue_work(kmultipathd, &m->trigger_event);
 934 }
 935
 936 /*
 937  * Switch to using the specified PG from the next I/O that gets mapped
 938  */
 939 static int switch_pg_num(struct multipath *m, const char *pgstr)
 940 {
 941         struct priority_group *pg;
 942         unsigned pgnum;
 943         unsigned long flags;
 944
 945         if (!pgstr || (sscanf(pgstr, "%u", &pgnum) != 1) || !pgnum ||
 946             (pgnum > m->nr_priority_groups)) {
 947                 DMWARN("invalid PG number supplied to switch_pg_num");
 948                 return -EINVAL;
 949         }
 950
 951         spin_lock_irqsave(&m->lock, flags);
 952         list_for_each_entry(pg, &m->priority_groups, list) {
 953                 pg->bypassed = 0;
 954                 if (--pgnum)
 955                         continue;
 956
 957                 m->current_pgpath = NULL;
 958                 m->current_pg = NULL;
 959                 m->next_pg = pg;
 960         }
 961         spin_unlock_irqrestore(&m->lock, flags);
 962
 963         queue_work(kmultipathd, &m->trigger_event);
 964         return 0;
 965 }
 966
 967 /*
 968  * Set/clear bypassed status of a PG.
 969  * PGs are numbered upwards from 1 in the order they were declared.
 970  */
 971 static int bypass_pg_num(struct multipath *m, const char *pgstr, int bypassed)
 972 {
 973         struct priority_group *pg;
 974         unsigned pgnum;
 975
 976         if (!pgstr || (sscanf(pgstr, "%u", &pgnum) != 1) || !pgnum ||
 977             (pgnum > m->nr_priority_groups)) {
 978                 DMWARN("invalid PG number supplied to bypass_pg");
 979                 return -EINVAL;
 980         }
 981
 982         list_for_each_entry(pg, &m->priority_groups, list) {
 983                 if (!--pgnum)
 984                         break;
 985         }
 986
 987         bypass_pg(m, pg, bypassed);
 988         return 0;
 989 }
 990
 991 /*
 992  * Should we retry pg_init immediately?
 993  */
 994 static int pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath)
 995 {
 996         unsigned long flags;
 997         int limit_reached = 0;
 998
 999         spin_lock_irqsave(&m->lock, flags);
1000
1001         if (m->pg_init_count <= m->pg_init_retries)
1002                 m->pg_init_required = 1;
1003         else
1004                 limit_reached = 1;
1005
1006         spin_unlock_irqrestore(&m->lock, flags);
1007
1008         return limit_reached;
1009 }
1010
1011 /*
1012  * pg_init must call this when it has completed its initialisation
1013  */
1014 void dm_pg_init_complete(struct dm_path *path, unsigned err_flags)
1015 {
1016         struct pgpath *pgpath = path_to_pgpath(path);
1017         struct priority_group *pg = pgpath->pg;
1018         struct multipath *m = pg->m;
1019         unsigned long flags;
1020
1021         /*
1022          * If requested, retry pg_init until maximum number of retries exceeded.
1023          * If retry not requested and PG already bypassed, always fail the path.
1024          */
1025         if (err_flags & MP_RETRY) {
1026                 if (pg_init_limit_reached(m, pgpath))
1027                         err_flags |= MP_FAIL_PATH;
1028         } else if (err_flags && pg->bypassed)
1029                 err_flags |= MP_FAIL_PATH;
1030
1031         if (err_flags & MP_FAIL_PATH)
1032                 fail_path(pgpath);
1033
1034         if (err_flags & MP_BYPASS_PG)
1035                 bypass_pg(m, pg, 1);
1036
1037         spin_lock_irqsave(&m->lock, flags);
1038         if (err_flags & ~MP_RETRY) {
1039                 m->current_pgpath = NULL;
1040                 m->current_pg = NULL;
1041         } else if (!m->pg_init_required)
1042                 m->queue_io = 0;
1043
1044         m->pg_init_in_progress = 0;
1045         queue_work(kmultipathd, &m->process_queued_ios);
1046         spin_unlock_irqrestore(&m->lock, flags);
1047 }
1048
1049 static void pg_init_done(struct dm_path *path, int errors)
1050 {
1051         struct pgpath *pgpath = path_to_pgpath(path);
1052         struct priority_group *pg = pgpath->pg;
1053         struct multipath *m = pg->m;
1054         unsigned long flags;
1055
1056         /* device or driver problems */
1057         switch (errors) {
1058         case SCSI_DH_OK:
1059                 break;
1060         case SCSI_DH_NOSYS:
1061                 if (!m->hw_handler_name) {
1062                         errors = 0;
1063                         break;
1064                 }
1065                 DMERR("Cannot failover device because scsi_dh_%s was not "
1066                       "loaded.", m->hw_handler_name);
1067                 /*
1068                  * Fail path for now, so we do not ping pong
1069                  */
1070                 fail_path(pgpath);
1071                 break;
1072         case SCSI_DH_DEV_TEMP_BUSY:
1073                 /*
1074                  * Probably doing something like FW upgrade on the
1075                  * controller so try the other pg.
1076                  */
1077                 bypass_pg(m, pg, 1);
1078                 break;
1079         /* TODO: For SCSI_DH_RETRY we should wait a couple seconds */
1080         case SCSI_DH_RETRY:
1081         case SCSI_DH_IMM_RETRY:
1082         case SCSI_DH_RES_TEMP_UNAVAIL:
1083                 if (pg_init_limit_reached(m, pgpath))
1084                         fail_path(pgpath);
1085                 errors = 0;
1086                 break;
1087         default:
1088                 /*
1089                  * We probably do not want to fail the path for a device
1090                  * error, but this is what the old dm did. In future
1091                  * patches we can do more advanced handling.
1092                  */
1093                 fail_path(pgpath);
1094         }
1095
1096         spin_lock_irqsave(&m->lock, flags);
1097         if (errors) {
1098                 DMERR("Could not failover device. Error %d.", errors);
1099                 m->current_pgpath = NULL;
1100                 m->current_pg = NULL;
1101         } else if (!m->pg_init_required) {
1102                 m->queue_io = 0;
1103                 pg->bypassed = 0;
1104         }
1105
1106         m->pg_init_in_progress = 0;
1107         queue_work(kmultipathd, &m->process_queued_ios);
1108         spin_unlock_irqrestore(&m->lock, flags);
1109 }
1110
1111 static void activate_path(struct work_struct *work)
1112 {
1113         int ret;
1114         struct multipath *m =
1115                 container_of(work, struct multipath, activate_path);
1116         struct dm_path *path = &m->current_pgpath->path;
1117
1118         ret = scsi_dh_activate(bdev_get_queue(path->dev->bdev));
1119         pg_init_done(path, ret);
1120 }
1121
1122 /*
1123  * end_io handling
1124  */
1125 static int do_end_io(struct multipath *m, struct bio *bio,
1126                      int error, struct dm_mpath_io *mpio)
1127 {
1128         unsigned long flags;
1129
1130         if (!error)
1131                 return 0;       /* I/O complete */
1132
1133         if ((error == -EWOULDBLOCK) && bio_rw_ahead(bio))
1134                 return error;
1135
1136         if (error == -EOPNOTSUPP)
1137                 return error;
1138
1139         spin_lock_irqsave(&m->lock, flags);
1140         if (!m->nr_valid_paths) {
1141                 if (__must_push_back(m)) {
1142                         spin_unlock_irqrestore(&m->lock, flags);
1143                         return DM_ENDIO_REQUEUE;
1144                 } else if (!m->queue_if_no_path) {
1145                         spin_unlock_irqrestore(&m->lock, flags);
1146                         return -EIO;
1147                 } else {
1148                         spin_unlock_irqrestore(&m->lock, flags);
1149                         goto requeue;
1150                 }
1151         }
1152         spin_unlock_irqrestore(&m->lock, flags);
1153
1154         if (mpio->pgpath)
1155                 fail_path(mpio->pgpath);
1156
1157       requeue:
1158         dm_bio_restore(&mpio->details, bio);
1159
1160         /* queue for the daemon to resubmit or fail */
1161         spin_lock_irqsave(&m->lock, flags);
1162         bio_list_add(&m->queued_ios, bio);
1163         m->queue_size++;
1164         if (!m->queue_io)
1165                 queue_work(kmultipathd, &m->process_queued_ios);
1166         spin_unlock_irqrestore(&m->lock, flags);
1167
1168         return DM_ENDIO_INCOMPLETE;     /* io not complete */
1169 }
1170
1171 static int multipath_end_io(struct dm_target *ti, struct bio *bio,
1172                             int error, union map_info *map_context)
1173 {
1174         struct multipath *m = ti->private;
1175         struct dm_mpath_io *mpio = map_context->ptr;
1176         struct pgpath *pgpath = mpio->pgpath;
1177         struct path_selector *ps;
1178         int r;
1179
1180         r  = do_end_io(m, bio, error, mpio);
1181         if (pgpath) {
1182                 ps = &pgpath->pg->ps;
1183                 if (ps->type->end_io)
1184                         ps->type->end_io(ps, &pgpath->path);
1185         }
1186         if (r != DM_ENDIO_INCOMPLETE)
1187                 mempool_free(mpio, m->mpio_pool);
1188
1189         return r;
1190 }
1191
1192 /*
1193  * Suspend can't complete until all the I/O is processed so if
1194  * the last path fails we must error any remaining I/O.
1195  * Note that if the freeze_bdev fails while suspending, the
1196  * queue_if_no_path state is lost - userspace should reset it.
1197  */
1198 static void multipath_presuspend(struct dm_target *ti)
1199 {
1200         struct multipath *m = (struct multipath *) ti->private;
1201
1202         queue_if_no_path(m, 0, 1);
1203 }
1204
1205 /*
1206  * Restore the queue_if_no_path setting.
1207  */
1208 static void multipath_resume(struct dm_target *ti)
1209 {
1210         struct multipath *m = (struct multipath *) ti->private;
1211         unsigned long flags;
1212
1213         spin_lock_irqsave(&m->lock, flags);
1214         m->queue_if_no_path = m->saved_queue_if_no_path;
1215         spin_unlock_irqrestore(&m->lock, flags);
1216 }
1217
1218 /*
1219  * Info output has the following format:
1220  * num_multipath_feature_args [multipath_feature_args]*
1221  * num_handler_status_args [handler_status_args]*
1222  * num_groups init_group_number
1223  *            [A|D|E num_ps_status_args [ps_status_args]*
1224  *             num_paths num_selector_args
1225  *             [path_dev A|F fail_count [selector_args]* ]+ ]+
1226  *
1227  * Table output has the following format (identical to the constructor string):
1228  * num_feature_args [features_args]*
1229  * num_handler_args hw_handler [hw_handler_args]*
1230  * num_groups init_group_number
1231  *     [priority selector-name num_ps_args [ps_args]*
1232  *      num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
1233  */
1234 static int multipath_status(struct dm_target *ti, status_type_t type,
1235                             char *result, unsigned int maxlen)
1236 {
1237         int sz = 0;
1238         unsigned long flags;
1239         struct multipath *m = (struct multipath *) ti->private;
1240         struct priority_group *pg;
1241         struct pgpath *p;
1242         unsigned pg_num;
1243         char state;
1244
1245         spin_lock_irqsave(&m->lock, flags);
1246
1247         /* Features */
1248         if (type == STATUSTYPE_INFO)
1249                 DMEMIT("2 %u %u ", m->queue_size, m->pg_init_count);
1250         else {
1251                 DMEMIT("%u ", m->queue_if_no_path +
1252                               (m->pg_init_retries > 0) * 2);
1253                 if (m->queue_if_no_path)
1254                         DMEMIT("queue_if_no_path ");
1255                 if (m->pg_init_retries)
1256                         DMEMIT("pg_init_retries %u ", m->pg_init_retries);
1257         }
1258
1259         if (!m->hw_handler_name || type == STATUSTYPE_INFO)
1260                 DMEMIT("0 ");
1261         else
1262                 DMEMIT("1 %s ", m->hw_handler_name);
1263
1264         DMEMIT("%u ", m->nr_priority_groups);
1265
1266         if (m->next_pg)
1267                 pg_num = m->next_pg->pg_num;
1268         else if (m->current_pg)
1269                 pg_num = m->current_pg->pg_num;
1270         else
1271                         pg_num = 1;
1272
1273         DMEMIT("%u ", pg_num);
1274
1275         switch (type) {
1276         case STATUSTYPE_INFO:
1277                 list_for_each_entry(pg, &m->priority_groups, list) {
1278                         if (pg->bypassed)
1279                                 state = 'D';    /* Disabled */
1280                         else if (pg == m->current_pg)
1281                                 state = 'A';    /* Currently Active */
1282                         else
1283                                 state = 'E';    /* Enabled */
1284
1285                         DMEMIT("%c ", state);
1286
1287                         if (pg->ps.type->status)
1288                                 sz += pg->ps.type->status(&pg->ps, NULL, type,
1289                                                           result + sz,
1290                                                           maxlen - sz);
1291                         else
1292                                 DMEMIT("0 ");
1293
1294                         DMEMIT("%u %u ", pg->nr_pgpaths,
1295                                pg->ps.type->info_args);
1296
1297                         list_for_each_entry(p, &pg->pgpaths, list) {
1298                                 DMEMIT("%s %s %u ", p->path.dev->name,
1299                                        p->path.is_active ? "A" : "F",
1300                                        p->fail_count);
1301                                 if (pg->ps.type->status)
1302                                         sz += pg->ps.type->status(&pg->ps,
1303                                               &p->path, type, result + sz,
1304                                               maxlen - sz);
1305                         }
1306                 }
1307                 break;
1308
1309         case STATUSTYPE_TABLE:
1310                 list_for_each_entry(pg, &m->priority_groups, list) {
1311                         DMEMIT("%s ", pg->ps.type->name);
1312
1313                         if (pg->ps.type->status)
1314                                 sz += pg->ps.type->status(&pg->ps, NULL, type,
1315                                                           result + sz,
1316                                                           maxlen - sz);
1317                         else
1318                                 DMEMIT("0 ");
1319
1320                         DMEMIT("%u %u ", pg->nr_pgpaths,
1321                                pg->ps.type->table_args);
1322
1323                         list_for_each_entry(p, &pg->pgpaths, list) {
1324                                 DMEMIT("%s ", p->path.dev->name);
1325                                 if (pg->ps.type->status)
1326                                         sz += pg->ps.type->status(&pg->ps,
1327                                               &p->path, type, result + sz,
1328                                               maxlen - sz);
1329                         }
1330                 }
1331                 break;
1332         }
1333
1334         spin_unlock_irqrestore(&m->lock, flags);
1335
1336         return 0;
1337 }
1338
1339 static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
1340 {
1341         int r;
1342         struct dm_dev *dev;
1343         struct multipath *m = (struct multipath *) ti->private;
1344         action_fn action;
1345
1346         if (argc == 1) {
1347                 if (!strnicmp(argv[0], MESG_STR("queue_if_no_path")))
1348                         return queue_if_no_path(m, 1, 0);
1349                 else if (!strnicmp(argv[0], MESG_STR("fail_if_no_path")))
1350                         return queue_if_no_path(m, 0, 0);
1351         }
1352
1353         if (argc != 2)
1354                 goto error;
1355
1356         if (!strnicmp(argv[0], MESG_STR("disable_group")))
1357                 return bypass_pg_num(m, argv[1], 1);
1358         else if (!strnicmp(argv[0], MESG_STR("enable_group")))
1359                 return bypass_pg_num(m, argv[1], 0);
1360         else if (!strnicmp(argv[0], MESG_STR("switch_group")))
1361                 return switch_pg_num(m, argv[1]);
1362         else if (!strnicmp(argv[0], MESG_STR("reinstate_path")))
1363                 action = reinstate_path;
1364         else if (!strnicmp(argv[0], MESG_STR("fail_path")))
1365                 action = fail_path;
1366         else
1367                 goto error;
1368
1369         r = dm_get_device(ti, argv[1], ti->begin, ti->len,
1370                           dm_table_get_mode(ti->table), &dev);
1371         if (r) {
1372                 DMWARN("message: error getting device %s",
1373                        argv[1]);
1374                 return -EINVAL;
1375         }
1376
1377         r = action_dev(m, dev, action);
1378
1379         dm_put_device(ti, dev);
1380
1381         return r;
1382
1383 error:
1384         DMWARN("Unrecognised multipath message received.");
1385         return -EINVAL;
1386 }
1387
1388 static int multipath_ioctl(struct dm_target *ti, struct inode *inode,
1389                            struct file *filp, unsigned int cmd,
1390                            unsigned long arg)
1391 {
1392         struct multipath *m = (struct multipath *) ti->private;
1393         struct block_device *bdev = NULL;
1394         unsigned long flags;
1395         struct file fake_file = {};
1396         struct dentry fake_dentry = {};
1397         int r = 0;
1398
1399         fake_file.f_path.dentry = &fake_dentry;
1400
1401         spin_lock_irqsave(&m->lock, flags);
1402
1403         if (!m->current_pgpath)
1404                 __choose_pgpath(m);
1405
1406         if (m->current_pgpath) {
1407                 bdev = m->current_pgpath->path.dev->bdev;
1408                 fake_dentry.d_inode = bdev->bd_inode;
1409                 fake_file.f_mode = m->current_pgpath->path.dev->mode;
1410         }
1411
1412         if (m->queue_io)
1413                 r = -EAGAIN;
1414         else if (!bdev)
1415                 r = -EIO;
1416
1417         spin_unlock_irqrestore(&m->lock, flags);
1418
1419         return r ? : blkdev_driver_ioctl(bdev->bd_inode, &fake_file,
1420                                          bdev->bd_disk, cmd, arg);
1421 }
1422
1423 /*-----------------------------------------------------------------
1424  * Module setup
1425  *---------------------------------------------------------------*/
1426 static struct target_type multipath_target = {
1427         .name = "multipath",
1428         .version = {1, 0, 5},
1429         .module = THIS_MODULE,
1430         .ctr = multipath_ctr,
1431         .dtr = multipath_dtr,
1432         .map = multipath_map,
1433         .end_io = multipath_end_io,
1434         .presuspend = multipath_presuspend,
1435         .resume = multipath_resume,
1436         .status = multipath_status,
1437         .message = multipath_message,
1438         .ioctl  = multipath_ioctl,
1439 };
1440
1441 static int __init dm_multipath_init(void)
1442 {
1443         int r;
1444
1445         /* allocate a slab for the dm_ios */
1446         _mpio_cache = KMEM_CACHE(dm_mpath_io, 0);
1447         if (!_mpio_cache)
1448                 return -ENOMEM;
1449
1450         r = dm_register_target(&multipath_target);
1451         if (r < 0) {
1452                 DMERR("register failed %d", r);
1453                 kmem_cache_destroy(_mpio_cache);
1454                 return -EINVAL;
1455         }
1456
1457         kmultipathd = create_workqueue("kmpathd");
1458         if (!kmultipathd) {
1459                 DMERR("failed to create workqueue kmpathd");
1460                 dm_unregister_target(&multipath_target);
1461                 kmem_cache_destroy(_mpio_cache);
1462                 return -ENOMEM;
1463         }
1464
1465         /*
1466          * A separate workqueue is used to handle the device handlers
1467          * to avoid overloading existing workqueue. Overloading the
1468          * old workqueue would also create a bottleneck in the
1469          * path of the storage hardware device activation.
1470          */
1471         kmpath_handlerd = create_singlethread_workqueue("kmpath_handlerd");
1472         if (!kmpath_handlerd) {
1473                 DMERR("failed to create workqueue kmpath_handlerd");
1474                 destroy_workqueue(kmultipathd);
1475                 dm_unregister_target(&multipath_target);
1476                 kmem_cache_destroy(_mpio_cache);
1477                 return -ENOMEM;
1478         }
1479
1480         DMINFO("version %u.%u.%u loaded",
1481                multipath_target.version[0], multipath_target.version[1],
1482                multipath_target.version[2]);
1483
1484         return r;
1485 }
1486
1487 static void __exit dm_multipath_exit(void)
1488 {
1489         int r;
1490
1491         destroy_workqueue(kmpath_handlerd);
1492         destroy_workqueue(kmultipathd);
1493
1494         r = dm_unregister_target(&multipath_target);
1495         if (r < 0)
1496                 DMERR("target unregister failed %d", r);
1497         kmem_cache_destroy(_mpio_cache);
1498 }
1499
1500 EXPORT_SYMBOL_GPL(dm_pg_init_complete);
1501
1502 module_init(dm_multipath_init);
1503 module_exit(dm_multipath_exit);
1504
1505 MODULE_DESCRIPTION(DM_NAME " multipath target");
1506 MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
1507 MODULE_LICENSE("GPL");