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