drivers/md/dm-log.c

   1 /*
   2  * Copyright (C) 2003 Sistina Software
   3  *
   4  * This file is released under the LGPL.
   5  */
   6
   7 #include <linux/init.h>
   8 #include <linux/slab.h>
   9 #include <linux/module.h>
  10 #include <linux/vmalloc.h>
  11
  12 #include "dm-log.h"
  13 #include "dm-io.h"
  14
  15 #define DM_MSG_PREFIX "mirror log"
  16
  17 static LIST_HEAD(_log_types);
  18 static DEFINE_SPINLOCK(_lock);
  19
  20 int dm_register_dirty_log_type(struct dirty_log_type *type)
  21 {
  22         spin_lock(&_lock);
  23         type->use_count = 0;
  24         list_add(&type->list, &_log_types);
  25         spin_unlock(&_lock);
  26
  27         return 0;
  28 }
  29
  30 int dm_unregister_dirty_log_type(struct dirty_log_type *type)
  31 {
  32         spin_lock(&_lock);
  33
  34         if (type->use_count)
  35                 DMWARN("Attempt to unregister a log type that is still in use");
  36         else
  37                 list_del(&type->list);
  38
  39         spin_unlock(&_lock);
  40
  41         return 0;
  42 }
  43
  44 static struct dirty_log_type *_get_type(const char *type_name)
  45 {
  46         struct dirty_log_type *type;
  47
  48         spin_lock(&_lock);
  49         list_for_each_entry (type, &_log_types, list)
  50                 if (!strcmp(type_name, type->name)) {
  51                         if (!type->use_count && !try_module_get(type->module)){
  52                                 spin_unlock(&_lock);
  53                                 return NULL;
  54                         }
  55                         type->use_count++;
  56                         spin_unlock(&_lock);
  57                         return type;
  58                 }
  59
  60         spin_unlock(&_lock);
  61         return NULL;
  62 }
  63
  64 /*
  65  * get_type
  66  * @type_name
  67  *
  68  * Attempt to retrieve the dirty_log_type by name.  If not already
  69  * available, attempt to load the appropriate module.
  70  *
  71  * Log modules are named "dm-log-" followed by the 'type_name'.
  72  * Modules may contain multiple types.
  73  * This function will first try the module "dm-log-<type_name>",
  74  * then truncate 'type_name' on the last '-' and try again.
  75  *
  76  * For example, if type_name was "clustered-disk", it would search
  77  * 'dm-log-clustered-disk' then 'dm-log-clustered'.
  78  *
  79  * Returns: dirty_log_type* on success, NULL on failure
  80  */
  81 static struct dirty_log_type *get_type(const char *type_name)
  82 {
  83         char *p, *type_name_dup;
  84         struct dirty_log_type *type;
  85
  86         type = _get_type(type_name);
  87         if (type)
  88                 return type;
  89
  90         type_name_dup = kstrdup(type_name, GFP_KERNEL);
  91         if (!type_name_dup) {
  92                 DMWARN("No memory left to attempt log module load for \"%s\"",
  93                        type_name);
  94                 return NULL;
  95         }
  96
  97         while (request_module("dm-log-%s", type_name_dup) ||
  98                !(type = _get_type(type_name))) {
  99                 p = strrchr(type_name_dup, '-');
 100                 if (!p)
 101                         break;
 102                 p[0] = '\0';
 103         }
 104
 105         if (!type)
 106                 DMWARN("Module for logging type \"%s\" not found.", type_name);
 107
 108         kfree(type_name_dup);
 109
 110         return type;
 111 }
 112
 113 static void put_type(struct dirty_log_type *type)
 114 {
 115         spin_lock(&_lock);
 116         if (!--type->use_count)
 117                 module_put(type->module);
 118         spin_unlock(&_lock);
 119 }
 120
 121 struct dirty_log *dm_create_dirty_log(const char *type_name, struct dm_target *ti,
 122                                       unsigned int argc, char **argv)
 123 {
 124         struct dirty_log_type *type;
 125         struct dirty_log *log;
 126
 127         log = kmalloc(sizeof(*log), GFP_KERNEL);
 128         if (!log)
 129                 return NULL;
 130
 131         type = get_type(type_name);
 132         if (!type) {
 133                 kfree(log);
 134                 return NULL;
 135         }
 136
 137         log->type = type;
 138         if (type->ctr(log, ti, argc, argv)) {
 139                 kfree(log);
 140                 put_type(type);
 141                 return NULL;
 142         }
 143
 144         return log;
 145 }
 146
 147 void dm_destroy_dirty_log(struct dirty_log *log)
 148 {
 149         log->type->dtr(log);
 150         put_type(log->type);
 151         kfree(log);
 152 }
 153
 154 /*-----------------------------------------------------------------
 155  * Persistent and core logs share a lot of their implementation.
 156  * FIXME: need a reload method to be called from a resume
 157  *---------------------------------------------------------------*/
 158 /*
 159  * Magic for persistent mirrors: "MiRr"
 160  */
 161 #define MIRROR_MAGIC 0x4D695272
 162
 163 /*
 164  * The on-disk version of the metadata.
 165  */
 166 #define MIRROR_DISK_VERSION 2
 167 #define LOG_OFFSET 2
 168
 169 struct log_header {
 170         uint32_t magic;
 171
 172         /*
 173          * Simple, incrementing version. no backward
 174          * compatibility.
 175          */
 176         uint32_t version;
 177         sector_t nr_regions;
 178 };
 179
 180 struct log_c {
 181         struct dm_target *ti;
 182         int touched;
 183         uint32_t region_size;
 184         unsigned int region_count;
 185         region_t sync_count;
 186
 187         unsigned bitset_uint32_count;
 188         uint32_t *clean_bits;
 189         uint32_t *sync_bits;
 190         uint32_t *recovering_bits;      /* FIXME: this seems excessive */
 191
 192         int sync_search;
 193
 194         /* Resync flag */
 195         enum sync {
 196                 DEFAULTSYNC,    /* Synchronize if necessary */
 197                 NOSYNC,         /* Devices known to be already in sync */
 198                 FORCESYNC,      /* Force a sync to happen */
 199         } sync;
 200
 201         struct dm_io_request io_req;
 202
 203         /*
 204          * Disk log fields
 205          */
 206         int log_dev_failed;
 207         struct dm_dev *log_dev;
 208         struct log_header header;
 209
 210         struct io_region header_location;
 211         struct log_header *disk_header;
 212 };
 213
 214 /*
 215  * The touched member needs to be updated every time we access
 216  * one of the bitsets.
 217  */
 218 static  inline int log_test_bit(uint32_t *bs, unsigned bit)
 219 {
 220         return ext2_test_bit(bit, (unsigned long *) bs) ? 1 : 0;
 221 }
 222
 223 static inline void log_set_bit(struct log_c *l,
 224                                uint32_t *bs, unsigned bit)
 225 {
 226         ext2_set_bit(bit, (unsigned long *) bs);
 227         l->touched = 1;
 228 }
 229
 230 static inline void log_clear_bit(struct log_c *l,
 231                                  uint32_t *bs, unsigned bit)
 232 {
 233         ext2_clear_bit(bit, (unsigned long *) bs);
 234         l->touched = 1;
 235 }
 236
 237 /*----------------------------------------------------------------
 238  * Header IO
 239  *--------------------------------------------------------------*/
 240 static void header_to_disk(struct log_header *core, struct log_header *disk)
 241 {
 242         disk->magic = cpu_to_le32(core->magic);
 243         disk->version = cpu_to_le32(core->version);
 244         disk->nr_regions = cpu_to_le64(core->nr_regions);
 245 }
 246
 247 static void header_from_disk(struct log_header *core, struct log_header *disk)
 248 {
 249         core->magic = le32_to_cpu(disk->magic);
 250         core->version = le32_to_cpu(disk->version);
 251         core->nr_regions = le64_to_cpu(disk->nr_regions);
 252 }
 253
 254 static int rw_header(struct log_c *lc, int rw)
 255 {
 256         lc->io_req.bi_rw = rw;
 257         lc->io_req.mem.ptr.vma = lc->disk_header;
 258         lc->io_req.notify.fn = NULL;
 259
 260         return dm_io(&lc->io_req, 1, &lc->header_location, NULL);
 261 }
 262
 263 static int read_header(struct log_c *log)
 264 {
 265         int r;
 266
 267         r = rw_header(log, READ);
 268         if (r)
 269                 return r;
 270
 271         header_from_disk(&log->header, log->disk_header);
 272
 273         /* New log required? */
 274         if (log->sync != DEFAULTSYNC || log->header.magic != MIRROR_MAGIC) {
 275                 log->header.magic = MIRROR_MAGIC;
 276                 log->header.version = MIRROR_DISK_VERSION;
 277                 log->header.nr_regions = 0;
 278         }
 279
 280 #ifdef __LITTLE_ENDIAN
 281         if (log->header.version == 1)
 282                 log->header.version = 2;
 283 #endif
 284
 285         if (log->header.version != MIRROR_DISK_VERSION) {
 286                 DMWARN("incompatible disk log version");
 287                 return -EINVAL;
 288         }
 289
 290         return 0;
 291 }
 292
 293 static inline int write_header(struct log_c *log)
 294 {
 295         header_to_disk(&log->header, log->disk_header);
 296         return rw_header(log, WRITE);
 297 }
 298
 299 /*----------------------------------------------------------------
 300  * core log constructor/destructor
 301  *
 302  * argv contains region_size followed optionally by [no]sync
 303  *--------------------------------------------------------------*/
 304 #define BYTE_SHIFT 3
 305 static int create_log_context(struct dirty_log *log, struct dm_target *ti,
 306                               unsigned int argc, char **argv,
 307                               struct dm_dev *dev)
 308 {
 309         enum sync sync = DEFAULTSYNC;
 310
 311         struct log_c *lc;
 312         uint32_t region_size;
 313         unsigned int region_count;
 314         size_t bitset_size, buf_size;
 315         int r;
 316
 317         if (argc < 1 || argc > 2) {
 318                 DMWARN("wrong number of arguments to mirror log");
 319                 return -EINVAL;
 320         }
 321
 322         if (argc > 1) {
 323                 if (!strcmp(argv[1], "sync"))
 324                         sync = FORCESYNC;
 325                 else if (!strcmp(argv[1], "nosync"))
 326                         sync = NOSYNC;
 327                 else {
 328                         DMWARN("unrecognised sync argument to mirror log: %s",
 329                                argv[1]);
 330                         return -EINVAL;
 331                 }
 332         }
 333
 334         if (sscanf(argv[0], "%u", &region_size) != 1) {
 335                 DMWARN("invalid region size string");
 336                 return -EINVAL;
 337         }
 338
 339         region_count = dm_sector_div_up(ti->len, region_size);
 340
 341         lc = kmalloc(sizeof(*lc), GFP_KERNEL);
 342         if (!lc) {
 343                 DMWARN("couldn't allocate core log");
 344                 return -ENOMEM;
 345         }
 346
 347         lc->ti = ti;
 348         lc->touched = 0;
 349         lc->region_size = region_size;
 350         lc->region_count = region_count;
 351         lc->sync = sync;
 352
 353         /*
 354          * Work out how many "unsigned long"s we need to hold the bitset.
 355          */
 356         bitset_size = dm_round_up(region_count,
 357                                   sizeof(*lc->clean_bits) << BYTE_SHIFT);
 358         bitset_size >>= BYTE_SHIFT;
 359
 360         lc->bitset_uint32_count = bitset_size / sizeof(*lc->clean_bits);
 361
 362         /*
 363          * Disk log?
 364          */
 365         if (!dev) {
 366                 lc->clean_bits = vmalloc(bitset_size);
 367                 if (!lc->clean_bits) {
 368                         DMWARN("couldn't allocate clean bitset");
 369                         kfree(lc);
 370                         return -ENOMEM;
 371                 }
 372                 lc->disk_header = NULL;
 373         } else {
 374                 lc->log_dev = dev;
 375                 lc->log_dev_failed = 0;
 376                 lc->header_location.bdev = lc->log_dev->bdev;
 377                 lc->header_location.sector = 0;
 378
 379                 /*
 380                  * Buffer holds both header and bitset.
 381                  */
 382                 buf_size = dm_round_up((LOG_OFFSET << SECTOR_SHIFT) +
 383                                        bitset_size, ti->limits.hardsect_size);
 384                 lc->header_location.count = buf_size >> SECTOR_SHIFT;
 385                 lc->io_req.mem.type = DM_IO_VMA;
 386                 lc->io_req.client = dm_io_client_create(dm_div_up(buf_size,
 387                                                                    PAGE_SIZE));
 388                 if (IS_ERR(lc->io_req.client)) {
 389                         r = PTR_ERR(lc->io_req.client);
 390                         DMWARN("couldn't allocate disk io client");
 391                         kfree(lc);
 392                         return -ENOMEM;
 393                 }
 394
 395                 lc->disk_header = vmalloc(buf_size);
 396                 if (!lc->disk_header) {
 397                         DMWARN("couldn't allocate disk log buffer");
 398                         kfree(lc);
 399                         return -ENOMEM;
 400                 }
 401
 402                 lc->clean_bits = (void *)lc->disk_header +
 403                                  (LOG_OFFSET << SECTOR_SHIFT);
 404         }
 405
 406         memset(lc->clean_bits, -1, bitset_size);
 407
 408         lc->sync_bits = vmalloc(bitset_size);
 409         if (!lc->sync_bits) {
 410                 DMWARN("couldn't allocate sync bitset");
 411                 if (!dev)
 412                         vfree(lc->clean_bits);
 413                 vfree(lc->disk_header);
 414                 kfree(lc);
 415                 return -ENOMEM;
 416         }
 417         memset(lc->sync_bits, (sync == NOSYNC) ? -1 : 0, bitset_size);
 418         lc->sync_count = (sync == NOSYNC) ? region_count : 0;
 419
 420         lc->recovering_bits = vmalloc(bitset_size);
 421         if (!lc->recovering_bits) {
 422                 DMWARN("couldn't allocate sync bitset");
 423                 vfree(lc->sync_bits);
 424                 if (!dev)
 425                         vfree(lc->clean_bits);
 426                 vfree(lc->disk_header);
 427                 kfree(lc);
 428                 return -ENOMEM;
 429         }
 430         memset(lc->recovering_bits, 0, bitset_size);
 431         lc->sync_search = 0;
 432         log->context = lc;
 433
 434         return 0;
 435 }
 436
 437 static int core_ctr(struct dirty_log *log, struct dm_target *ti,
 438                     unsigned int argc, char **argv)
 439 {
 440         return create_log_context(log, ti, argc, argv, NULL);
 441 }
 442
 443 static void destroy_log_context(struct log_c *lc)
 444 {
 445         vfree(lc->sync_bits);
 446         vfree(lc->recovering_bits);
 447         kfree(lc);
 448 }
 449
 450 static void core_dtr(struct dirty_log *log)
 451 {
 452         struct log_c *lc = (struct log_c *) log->context;
 453
 454         vfree(lc->clean_bits);
 455         destroy_log_context(lc);
 456 }
 457
 458 /*----------------------------------------------------------------
 459  * disk log constructor/destructor
 460  *
 461  * argv contains log_device region_size followed optionally by [no]sync
 462  *--------------------------------------------------------------*/
 463 static int disk_ctr(struct dirty_log *log, struct dm_target *ti,
 464                     unsigned int argc, char **argv)
 465 {
 466         int r;
 467         struct dm_dev *dev;
 468
 469         if (argc < 2 || argc > 3) {
 470                 DMWARN("wrong number of arguments to disk mirror log");
 471                 return -EINVAL;
 472         }
 473
 474         r = dm_get_device(ti, argv[0], 0, 0 /* FIXME */,
 475                           FMODE_READ | FMODE_WRITE, &dev);
 476         if (r)
 477                 return r;
 478
 479         r = create_log_context(log, ti, argc - 1, argv + 1, dev);
 480         if (r) {
 481                 dm_put_device(ti, dev);
 482                 return r;
 483         }
 484
 485         return 0;
 486 }
 487
 488 static void disk_dtr(struct dirty_log *log)
 489 {
 490         struct log_c *lc = (struct log_c *) log->context;
 491
 492         dm_put_device(lc->ti, lc->log_dev);
 493         vfree(lc->disk_header);
 494         dm_io_client_destroy(lc->io_req.client);
 495         destroy_log_context(lc);
 496 }
 497
 498 static int count_bits32(uint32_t *addr, unsigned size)
 499 {
 500         int count = 0, i;
 501
 502         for (i = 0; i < size; i++) {
 503                 count += hweight32(*(addr+i));
 504         }
 505         return count;
 506 }
 507
 508 static void fail_log_device(struct log_c *lc)
 509 {
 510         if (lc->log_dev_failed)
 511                 return;
 512
 513         lc->log_dev_failed = 1;
 514         dm_table_event(lc->ti->table);
 515 }
 516
 517 static int disk_resume(struct dirty_log *log)
 518 {
 519         int r;
 520         unsigned i;
 521         struct log_c *lc = (struct log_c *) log->context;
 522         size_t size = lc->bitset_uint32_count * sizeof(uint32_t);
 523
 524         /* read the disk header */
 525         r = read_header(lc);
 526         if (r) {
 527                 DMWARN("%s: Failed to read header on mirror log device",
 528                        lc->log_dev->name);
 529                 fail_log_device(lc);
 530                 /*
 531                  * If the log device cannot be read, we must assume
 532                  * all regions are out-of-sync.  If we simply return
 533                  * here, the state will be uninitialized and could
 534                  * lead us to return 'in-sync' status for regions
 535                  * that are actually 'out-of-sync'.
 536                  */
 537                 lc->header.nr_regions = 0;
 538         }
 539
 540         /* set or clear any new bits -- device has grown */
 541         if (lc->sync == NOSYNC)
 542                 for (i = lc->header.nr_regions; i < lc->region_count; i++)
 543                         /* FIXME: amazingly inefficient */
 544                         log_set_bit(lc, lc->clean_bits, i);
 545         else
 546                 for (i = lc->header.nr_regions; i < lc->region_count; i++)
 547                         /* FIXME: amazingly inefficient */
 548                         log_clear_bit(lc, lc->clean_bits, i);
 549
 550         /* clear any old bits -- device has shrunk */
 551         for (i = lc->region_count; i % (sizeof(*lc->clean_bits) << BYTE_SHIFT); i++)
 552                 log_clear_bit(lc, lc->clean_bits, i);
 553
 554         /* copy clean across to sync */
 555         memcpy(lc->sync_bits, lc->clean_bits, size);
 556         lc->sync_count = count_bits32(lc->clean_bits, lc->bitset_uint32_count);
 557         lc->sync_search = 0;
 558
 559         /* set the correct number of regions in the header */
 560         lc->header.nr_regions = lc->region_count;
 561
 562         /* write the new header */
 563         r = write_header(lc);
 564         if (r) {
 565                 DMWARN("%s: Failed to write header on mirror log device",
 566                        lc->log_dev->name);
 567                 fail_log_device(lc);
 568         }
 569
 570         return r;
 571 }
 572
 573 static uint32_t core_get_region_size(struct dirty_log *log)
 574 {
 575         struct log_c *lc = (struct log_c *) log->context;
 576         return lc->region_size;
 577 }
 578
 579 static int core_resume(struct dirty_log *log)
 580 {
 581         struct log_c *lc = (struct log_c *) log->context;
 582         lc->sync_search = 0;
 583         return 0;
 584 }
 585
 586 static int core_is_clean(struct dirty_log *log, region_t region)
 587 {
 588         struct log_c *lc = (struct log_c *) log->context;
 589         return log_test_bit(lc->clean_bits, region);
 590 }
 591
 592 static int core_in_sync(struct dirty_log *log, region_t region, int block)
 593 {
 594         struct log_c *lc = (struct log_c *) log->context;
 595         return log_test_bit(lc->sync_bits, region);
 596 }
 597
 598 static int core_flush(struct dirty_log *log)
 599 {
 600         /* no op */
 601         return 0;
 602 }
 603
 604 static int disk_flush(struct dirty_log *log)
 605 {
 606         int r;
 607         struct log_c *lc = (struct log_c *) log->context;
 608
 609         /* only write if the log has changed */
 610         if (!lc->touched)
 611                 return 0;
 612
 613         r = write_header(lc);
 614         if (r)
 615                 fail_log_device(lc);
 616         else
 617                 lc->touched = 0;
 618
 619         return r;
 620 }
 621
 622 static void core_mark_region(struct dirty_log *log, region_t region)
 623 {
 624         struct log_c *lc = (struct log_c *) log->context;
 625         log_clear_bit(lc, lc->clean_bits, region);
 626 }
 627
 628 static void core_clear_region(struct dirty_log *log, region_t region)
 629 {
 630         struct log_c *lc = (struct log_c *) log->context;
 631         log_set_bit(lc, lc->clean_bits, region);
 632 }
 633
 634 static int core_get_resync_work(struct dirty_log *log, region_t *region)
 635 {
 636         struct log_c *lc = (struct log_c *) log->context;
 637
 638         if (lc->sync_search >= lc->region_count)
 639                 return 0;
 640
 641         do {
 642                 *region = ext2_find_next_zero_bit(
 643                                              (unsigned long *) lc->sync_bits,
 644                                              lc->region_count,
 645                                              lc->sync_search);
 646                 lc->sync_search = *region + 1;
 647
 648                 if (*region >= lc->region_count)
 649                         return 0;
 650
 651         } while (log_test_bit(lc->recovering_bits, *region));
 652
 653         log_set_bit(lc, lc->recovering_bits, *region);
 654         return 1;
 655 }
 656
 657 static void core_set_region_sync(struct dirty_log *log, region_t region,
 658                                  int in_sync)
 659 {
 660         struct log_c *lc = (struct log_c *) log->context;
 661
 662         log_clear_bit(lc, lc->recovering_bits, region);
 663         if (in_sync) {
 664                 log_set_bit(lc, lc->sync_bits, region);
 665                 lc->sync_count++;
 666         } else if (log_test_bit(lc->sync_bits, region)) {
 667                 lc->sync_count--;
 668                 log_clear_bit(lc, lc->sync_bits, region);
 669         }
 670 }
 671
 672 static region_t core_get_sync_count(struct dirty_log *log)
 673 {
 674         struct log_c *lc = (struct log_c *) log->context;
 675
 676         return lc->sync_count;
 677 }
 678
 679 #define DMEMIT_SYNC \
 680         if (lc->sync != DEFAULTSYNC) \
 681                 DMEMIT("%ssync ", lc->sync == NOSYNC ? "no" : "")
 682
 683 static int core_status(struct dirty_log *log, status_type_t status,
 684                        char *result, unsigned int maxlen)
 685 {
 686         int sz = 0;
 687         struct log_c *lc = log->context;
 688
 689         switch(status) {
 690         case STATUSTYPE_INFO:
 691                 DMEMIT("1 %s", log->type->name);
 692                 break;
 693
 694         case STATUSTYPE_TABLE:
 695                 DMEMIT("%s %u %u ", log->type->name,
 696                        lc->sync == DEFAULTSYNC ? 1 : 2, lc->region_size);
 697                 DMEMIT_SYNC;
 698         }
 699
 700         return sz;
 701 }
 702
 703 static int disk_status(struct dirty_log *log, status_type_t status,
 704                        char *result, unsigned int maxlen)
 705 {
 706         int sz = 0;
 707         struct log_c *lc = log->context;
 708
 709         switch(status) {
 710         case STATUSTYPE_INFO:
 711                 DMEMIT("3 %s %s %c", log->type->name, lc->log_dev->name,
 712                        lc->log_dev_failed ? 'D' : 'A');
 713                 break;
 714
 715         case STATUSTYPE_TABLE:
 716                 DMEMIT("%s %u %s %u ", log->type->name,
 717                        lc->sync == DEFAULTSYNC ? 2 : 3, lc->log_dev->name,
 718                        lc->region_size);
 719                 DMEMIT_SYNC;
 720         }
 721
 722         return sz;
 723 }
 724
 725 static struct dirty_log_type _core_type = {
 726         .name = "core",
 727         .module = THIS_MODULE,
 728         .ctr = core_ctr,
 729         .dtr = core_dtr,
 730         .resume = core_resume,
 731         .get_region_size = core_get_region_size,
 732         .is_clean = core_is_clean,
 733         .in_sync = core_in_sync,
 734         .flush = core_flush,
 735         .mark_region = core_mark_region,
 736         .clear_region = core_clear_region,
 737         .get_resync_work = core_get_resync_work,
 738         .set_region_sync = core_set_region_sync,
 739         .get_sync_count = core_get_sync_count,
 740         .status = core_status,
 741 };
 742
 743 static struct dirty_log_type _disk_type = {
 744         .name = "disk",
 745         .module = THIS_MODULE,
 746         .ctr = disk_ctr,
 747         .dtr = disk_dtr,
 748         .postsuspend = disk_flush,
 749         .resume = disk_resume,
 750         .get_region_size = core_get_region_size,
 751         .is_clean = core_is_clean,
 752         .in_sync = core_in_sync,
 753         .flush = disk_flush,
 754         .mark_region = core_mark_region,
 755         .clear_region = core_clear_region,
 756         .get_resync_work = core_get_resync_work,
 757         .set_region_sync = core_set_region_sync,
 758         .get_sync_count = core_get_sync_count,
 759         .status = disk_status,
 760 };
 761
 762 int __init dm_dirty_log_init(void)
 763 {
 764         int r;
 765
 766         r = dm_register_dirty_log_type(&_core_type);
 767         if (r)
 768                 DMWARN("couldn't register core log");
 769
 770         r = dm_register_dirty_log_type(&_disk_type);
 771         if (r) {
 772                 DMWARN("couldn't register disk type");
 773                 dm_unregister_dirty_log_type(&_core_type);
 774         }
 775
 776         return r;
 777 }
 778
 779 void dm_dirty_log_exit(void)
 780 {
 781         dm_unregister_dirty_log_type(&_disk_type);
 782         dm_unregister_dirty_log_type(&_core_type);
 783 }
 784
 785 EXPORT_SYMBOL(dm_register_dirty_log_type);
 786 EXPORT_SYMBOL(dm_unregister_dirty_log_type);
 787 EXPORT_SYMBOL(dm_create_dirty_log);
 788 EXPORT_SYMBOL(dm_destroy_dirty_log);