git.oblomov.eu Git - linux-2.6/blob - 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 static void put_type(struct dirty_log_type *type)
  65 {
  66         spin_lock(&_lock);
  67         if (!--type->use_count)
  68                 module_put(type->module);
  69         spin_unlock(&_lock);
  70 }
  71
  72 struct dirty_log *dm_create_dirty_log(const char *type_name, struct dm_target *ti,
  73                                       unsigned int argc, char **argv)
  74 {
  75         struct dirty_log_type *type;
  76         struct dirty_log *log;
  77
  78         log = kmalloc(sizeof(*log), GFP_KERNEL);
  79         if (!log)
  80                 return NULL;
  81
  82         type = get_type(type_name);
  83         if (!type) {
  84                 kfree(log);
  85                 return NULL;
  86         }
  87
  88         log->type = type;
  89         if (type->ctr(log, ti, argc, argv)) {
  90                 kfree(log);
  91                 put_type(type);
  92                 return NULL;
  93         }
  94
  95         return log;
  96 }
  97
  98 void dm_destroy_dirty_log(struct dirty_log *log)
  99 {
 100         log->type->dtr(log);
 101         put_type(log->type);
 102         kfree(log);
 103 }
 104
 105 /*-----------------------------------------------------------------
 106  * Persistent and core logs share a lot of their implementation.
 107  * FIXME: need a reload method to be called from a resume
 108  *---------------------------------------------------------------*/
 109 /*
 110  * Magic for persistent mirrors: "MiRr"
 111  */
 112 #define MIRROR_MAGIC 0x4D695272
 113
 114 /*
 115  * The on-disk version of the metadata.
 116  */
 117 #define MIRROR_DISK_VERSION 2
 118 #define LOG_OFFSET 2
 119
 120 struct log_header {
 121         uint32_t magic;
 122
 123         /*
 124          * Simple, incrementing version. no backward
 125          * compatibility.
 126          */
 127         uint32_t version;
 128         sector_t nr_regions;
 129 };
 130
 131 struct log_c {
 132         struct dm_target *ti;
 133         int touched;
 134         uint32_t region_size;
 135         unsigned int region_count;
 136         region_t sync_count;
 137
 138         unsigned bitset_uint32_count;
 139         uint32_t *clean_bits;
 140         uint32_t *sync_bits;
 141         uint32_t *recovering_bits;      /* FIXME: this seems excessive */
 142
 143         int sync_search;
 144
 145         /* Resync flag */
 146         enum sync {
 147                 DEFAULTSYNC,    /* Synchronize if necessary */
 148                 NOSYNC,         /* Devices known to be already in sync */
 149                 FORCESYNC,      /* Force a sync to happen */
 150         } sync;
 151
 152         /*
 153          * Disk log fields
 154          */
 155         struct dm_dev *log_dev;
 156         struct log_header header;
 157
 158         struct io_region header_location;
 159         struct log_header *disk_header;
 160 };
 161
 162 /*
 163  * The touched member needs to be updated every time we access
 164  * one of the bitsets.
 165  */
 166 static  inline int log_test_bit(uint32_t *bs, unsigned bit)
 167 {
 168         return ext2_test_bit(bit, (unsigned long *) bs) ? 1 : 0;
 169 }
 170
 171 static inline void log_set_bit(struct log_c *l,
 172                                uint32_t *bs, unsigned bit)
 173 {
 174         ext2_set_bit(bit, (unsigned long *) bs);
 175         l->touched = 1;
 176 }
 177
 178 static inline void log_clear_bit(struct log_c *l,
 179                                  uint32_t *bs, unsigned bit)
 180 {
 181         ext2_clear_bit(bit, (unsigned long *) bs);
 182         l->touched = 1;
 183 }
 184
 185 /*----------------------------------------------------------------
 186  * Header IO
 187  *--------------------------------------------------------------*/
 188 static void header_to_disk(struct log_header *core, struct log_header *disk)
 189 {
 190         disk->magic = cpu_to_le32(core->magic);
 191         disk->version = cpu_to_le32(core->version);
 192         disk->nr_regions = cpu_to_le64(core->nr_regions);
 193 }
 194
 195 static void header_from_disk(struct log_header *core, struct log_header *disk)
 196 {
 197         core->magic = le32_to_cpu(disk->magic);
 198         core->version = le32_to_cpu(disk->version);
 199         core->nr_regions = le64_to_cpu(disk->nr_regions);
 200 }
 201
 202 static int read_header(struct log_c *log)
 203 {
 204         int r;
 205         unsigned long ebits;
 206
 207         r = dm_io_sync_vm(1, &log->header_location, READ,
 208                           log->disk_header, &ebits);
 209         if (r)
 210                 return r;
 211
 212         header_from_disk(&log->header, log->disk_header);
 213
 214         /* New log required? */
 215         if (log->sync != DEFAULTSYNC || log->header.magic != MIRROR_MAGIC) {
 216                 log->header.magic = MIRROR_MAGIC;
 217                 log->header.version = MIRROR_DISK_VERSION;
 218                 log->header.nr_regions = 0;
 219         }
 220
 221 #ifdef __LITTLE_ENDIAN
 222         if (log->header.version == 1)
 223                 log->header.version = 2;
 224 #endif
 225
 226         if (log->header.version != MIRROR_DISK_VERSION) {
 227                 DMWARN("incompatible disk log version");
 228                 return -EINVAL;
 229         }
 230
 231         return 0;
 232 }
 233
 234 static inline int write_header(struct log_c *log)
 235 {
 236         unsigned long ebits;
 237
 238         header_to_disk(&log->header, log->disk_header);
 239         return dm_io_sync_vm(1, &log->header_location, WRITE,
 240                              log->disk_header, &ebits);
 241 }
 242
 243 /*----------------------------------------------------------------
 244  * core log constructor/destructor
 245  *
 246  * argv contains region_size followed optionally by [no]sync
 247  *--------------------------------------------------------------*/
 248 #define BYTE_SHIFT 3
 249 static int create_log_context(struct dirty_log *log, struct dm_target *ti,
 250                               unsigned int argc, char **argv,
 251                               struct dm_dev *dev)
 252 {
 253         enum sync sync = DEFAULTSYNC;
 254
 255         struct log_c *lc;
 256         uint32_t region_size;
 257         unsigned int region_count;
 258         size_t bitset_size, buf_size;
 259
 260         if (argc < 1 || argc > 2) {
 261                 DMWARN("wrong number of arguments to mirror log");
 262                 return -EINVAL;
 263         }
 264
 265         if (argc > 1) {
 266                 if (!strcmp(argv[1], "sync"))
 267                         sync = FORCESYNC;
 268                 else if (!strcmp(argv[1], "nosync"))
 269                         sync = NOSYNC;
 270                 else {
 271                         DMWARN("unrecognised sync argument to mirror log: %s",
 272                                argv[1]);
 273                         return -EINVAL;
 274                 }
 275         }
 276
 277         if (sscanf(argv[0], "%u", &region_size) != 1) {
 278                 DMWARN("invalid region size string");
 279                 return -EINVAL;
 280         }
 281
 282         region_count = dm_sector_div_up(ti->len, region_size);
 283
 284         lc = kmalloc(sizeof(*lc), GFP_KERNEL);
 285         if (!lc) {
 286                 DMWARN("couldn't allocate core log");
 287                 return -ENOMEM;
 288         }
 289
 290         lc->ti = ti;
 291         lc->touched = 0;
 292         lc->region_size = region_size;
 293         lc->region_count = region_count;
 294         lc->sync = sync;
 295
 296         /*
 297          * Work out how many "unsigned long"s we need to hold the bitset.
 298          */
 299         bitset_size = dm_round_up(region_count,
 300                                   sizeof(*lc->clean_bits) << BYTE_SHIFT);
 301         bitset_size >>= BYTE_SHIFT;
 302
 303         lc->bitset_uint32_count = bitset_size / sizeof(*lc->clean_bits);
 304
 305         /*
 306          * Disk log?
 307          */
 308         if (!dev) {
 309                 lc->clean_bits = vmalloc(bitset_size);
 310                 if (!lc->clean_bits) {
 311                         DMWARN("couldn't allocate clean bitset");
 312                         kfree(lc);
 313                         return -ENOMEM;
 314                 }
 315                 lc->disk_header = NULL;
 316         } else {
 317                 lc->log_dev = dev;
 318                 lc->header_location.bdev = lc->log_dev->bdev;
 319                 lc->header_location.sector = 0;
 320
 321                 /*
 322                  * Buffer holds both header and bitset.
 323                  */
 324                 buf_size = dm_round_up((LOG_OFFSET << SECTOR_SHIFT) +
 325                                        bitset_size, ti->limits.hardsect_size);
 326                 lc->header_location.count = buf_size >> SECTOR_SHIFT;
 327
 328                 lc->disk_header = vmalloc(buf_size);
 329                 if (!lc->disk_header) {
 330                         DMWARN("couldn't allocate disk log buffer");
 331                         kfree(lc);
 332                         return -ENOMEM;
 333                 }
 334
 335                 lc->clean_bits = (void *)lc->disk_header +
 336                                  (LOG_OFFSET << SECTOR_SHIFT);
 337         }
 338
 339         memset(lc->clean_bits, -1, bitset_size);
 340
 341         lc->sync_bits = vmalloc(bitset_size);
 342         if (!lc->sync_bits) {
 343                 DMWARN("couldn't allocate sync bitset");
 344                 if (!dev)
 345                         vfree(lc->clean_bits);
 346                 vfree(lc->disk_header);
 347                 kfree(lc);
 348                 return -ENOMEM;
 349         }
 350         memset(lc->sync_bits, (sync == NOSYNC) ? -1 : 0, bitset_size);
 351         lc->sync_count = (sync == NOSYNC) ? region_count : 0;
 352
 353         lc->recovering_bits = vmalloc(bitset_size);
 354         if (!lc->recovering_bits) {
 355                 DMWARN("couldn't allocate sync bitset");
 356                 vfree(lc->sync_bits);
 357                 if (!dev)
 358                         vfree(lc->clean_bits);
 359                 vfree(lc->disk_header);
 360                 kfree(lc);
 361                 return -ENOMEM;
 362         }
 363         memset(lc->recovering_bits, 0, bitset_size);
 364         lc->sync_search = 0;
 365         log->context = lc;
 366
 367         return 0;
 368 }
 369
 370 static int core_ctr(struct dirty_log *log, struct dm_target *ti,
 371                     unsigned int argc, char **argv)
 372 {
 373         return create_log_context(log, ti, argc, argv, NULL);
 374 }
 375
 376 static void destroy_log_context(struct log_c *lc)
 377 {
 378         vfree(lc->sync_bits);
 379         vfree(lc->recovering_bits);
 380         kfree(lc);
 381 }
 382
 383 static void core_dtr(struct dirty_log *log)
 384 {
 385         struct log_c *lc = (struct log_c *) log->context;
 386
 387         vfree(lc->clean_bits);
 388         destroy_log_context(lc);
 389 }
 390
 391 /*----------------------------------------------------------------
 392  * disk log constructor/destructor
 393  *
 394  * argv contains log_device region_size followed optionally by [no]sync
 395  *--------------------------------------------------------------*/
 396 static int disk_ctr(struct dirty_log *log, struct dm_target *ti,
 397                     unsigned int argc, char **argv)
 398 {
 399         int r;
 400         struct dm_dev *dev;
 401
 402         if (argc < 2 || argc > 3) {
 403                 DMWARN("wrong number of arguments to disk mirror log");
 404                 return -EINVAL;
 405         }
 406
 407         r = dm_get_device(ti, argv[0], 0, 0 /* FIXME */,
 408                           FMODE_READ | FMODE_WRITE, &dev);
 409         if (r)
 410                 return r;
 411
 412         r = create_log_context(log, ti, argc - 1, argv + 1, dev);
 413         if (r) {
 414                 dm_put_device(ti, dev);
 415                 return r;
 416         }
 417
 418         return 0;
 419 }
 420
 421 static void disk_dtr(struct dirty_log *log)
 422 {
 423         struct log_c *lc = (struct log_c *) log->context;
 424
 425         dm_put_device(lc->ti, lc->log_dev);
 426         vfree(lc->disk_header);
 427         destroy_log_context(lc);
 428 }
 429
 430 static int count_bits32(uint32_t *addr, unsigned size)
 431 {
 432         int count = 0, i;
 433
 434         for (i = 0; i < size; i++) {
 435                 count += hweight32(*(addr+i));
 436         }
 437         return count;
 438 }
 439
 440 static int disk_resume(struct dirty_log *log)
 441 {
 442         int r;
 443         unsigned i;
 444         struct log_c *lc = (struct log_c *) log->context;
 445         size_t size = lc->bitset_uint32_count * sizeof(uint32_t);
 446
 447         /* read the disk header */
 448         r = read_header(lc);
 449         if (r)
 450                 return r;
 451
 452         /* set or clear any new bits -- device has grown */
 453         if (lc->sync == NOSYNC)
 454                 for (i = lc->header.nr_regions; i < lc->region_count; i++)
 455                         /* FIXME: amazingly inefficient */
 456                         log_set_bit(lc, lc->clean_bits, i);
 457         else
 458                 for (i = lc->header.nr_regions; i < lc->region_count; i++)
 459                         /* FIXME: amazingly inefficient */
 460                         log_clear_bit(lc, lc->clean_bits, i);
 461
 462         /* clear any old bits -- device has shrunk */
 463         for (i = lc->region_count; i % (sizeof(*lc->clean_bits) << BYTE_SHIFT); i++)
 464                 log_clear_bit(lc, lc->clean_bits, i);
 465
 466         /* copy clean across to sync */
 467         memcpy(lc->sync_bits, lc->clean_bits, size);
 468         lc->sync_count = count_bits32(lc->clean_bits, lc->bitset_uint32_count);
 469         lc->sync_search = 0;
 470
 471         /* set the correct number of regions in the header */
 472         lc->header.nr_regions = lc->region_count;
 473
 474         /* write the new header */
 475         return write_header(lc);
 476 }
 477
 478 static uint32_t core_get_region_size(struct dirty_log *log)
 479 {
 480         struct log_c *lc = (struct log_c *) log->context;
 481         return lc->region_size;
 482 }
 483
 484 static int core_resume(struct dirty_log *log)
 485 {
 486         struct log_c *lc = (struct log_c *) log->context;
 487         lc->sync_search = 0;
 488         return 0;
 489 }
 490
 491 static int core_is_clean(struct dirty_log *log, region_t region)
 492 {
 493         struct log_c *lc = (struct log_c *) log->context;
 494         return log_test_bit(lc->clean_bits, region);
 495 }
 496
 497 static int core_in_sync(struct dirty_log *log, region_t region, int block)
 498 {
 499         struct log_c *lc = (struct log_c *) log->context;
 500         return log_test_bit(lc->sync_bits, region);
 501 }
 502
 503 static int core_flush(struct dirty_log *log)
 504 {
 505         /* no op */
 506         return 0;
 507 }
 508
 509 static int disk_flush(struct dirty_log *log)
 510 {
 511         int r;
 512         struct log_c *lc = (struct log_c *) log->context;
 513
 514         /* only write if the log has changed */
 515         if (!lc->touched)
 516                 return 0;
 517
 518         r = write_header(lc);
 519         if (!r)
 520                 lc->touched = 0;
 521
 522         return r;
 523 }
 524
 525 static void core_mark_region(struct dirty_log *log, region_t region)
 526 {
 527         struct log_c *lc = (struct log_c *) log->context;
 528         log_clear_bit(lc, lc->clean_bits, region);
 529 }
 530
 531 static void core_clear_region(struct dirty_log *log, region_t region)
 532 {
 533         struct log_c *lc = (struct log_c *) log->context;
 534         log_set_bit(lc, lc->clean_bits, region);
 535 }
 536
 537 static int core_get_resync_work(struct dirty_log *log, region_t *region)
 538 {
 539         struct log_c *lc = (struct log_c *) log->context;
 540
 541         if (lc->sync_search >= lc->region_count)
 542                 return 0;
 543
 544         do {
 545                 *region = ext2_find_next_zero_bit(
 546                                              (unsigned long *) lc->sync_bits,
 547                                              lc->region_count,
 548                                              lc->sync_search);
 549                 lc->sync_search = *region + 1;
 550
 551                 if (*region >= lc->region_count)
 552                         return 0;
 553
 554         } while (log_test_bit(lc->recovering_bits, *region));
 555
 556         log_set_bit(lc, lc->recovering_bits, *region);
 557         return 1;
 558 }
 559
 560 static void core_set_region_sync(struct dirty_log *log, region_t region,
 561                                  int in_sync)
 562 {
 563         struct log_c *lc = (struct log_c *) log->context;
 564
 565         log_clear_bit(lc, lc->recovering_bits, region);
 566         if (in_sync) {
 567                 log_set_bit(lc, lc->sync_bits, region);
 568                 lc->sync_count++;
 569         } else if (log_test_bit(lc->sync_bits, region)) {
 570                 lc->sync_count--;
 571                 log_clear_bit(lc, lc->sync_bits, region);
 572         }
 573 }
 574
 575 static region_t core_get_sync_count(struct dirty_log *log)
 576 {
 577         struct log_c *lc = (struct log_c *) log->context;
 578
 579         return lc->sync_count;
 580 }
 581
 582 #define DMEMIT_SYNC \
 583         if (lc->sync != DEFAULTSYNC) \
 584                 DMEMIT("%ssync ", lc->sync == NOSYNC ? "no" : "")
 585
 586 static int core_status(struct dirty_log *log, status_type_t status,
 587                        char *result, unsigned int maxlen)
 588 {
 589         int sz = 0;
 590         struct log_c *lc = log->context;
 591
 592         switch(status) {
 593         case STATUSTYPE_INFO:
 594                 break;
 595
 596         case STATUSTYPE_TABLE:
 597                 DMEMIT("%s %u %u ", log->type->name,
 598                        lc->sync == DEFAULTSYNC ? 1 : 2, lc->region_size);
 599                 DMEMIT_SYNC;
 600         }
 601
 602         return sz;
 603 }
 604
 605 static int disk_status(struct dirty_log *log, status_type_t status,
 606                        char *result, unsigned int maxlen)
 607 {
 608         int sz = 0;
 609         char buffer[16];
 610         struct log_c *lc = log->context;
 611
 612         switch(status) {
 613         case STATUSTYPE_INFO:
 614                 break;
 615
 616         case STATUSTYPE_TABLE:
 617                 format_dev_t(buffer, lc->log_dev->bdev->bd_dev);
 618                 DMEMIT("%s %u %s %u ", log->type->name,
 619                        lc->sync == DEFAULTSYNC ? 2 : 3, buffer,
 620                        lc->region_size);
 621                 DMEMIT_SYNC;
 622         }
 623
 624         return sz;
 625 }
 626
 627 static struct dirty_log_type _core_type = {
 628         .name = "core",
 629         .module = THIS_MODULE,
 630         .ctr = core_ctr,
 631         .dtr = core_dtr,
 632         .resume = core_resume,
 633         .get_region_size = core_get_region_size,
 634         .is_clean = core_is_clean,
 635         .in_sync = core_in_sync,
 636         .flush = core_flush,
 637         .mark_region = core_mark_region,
 638         .clear_region = core_clear_region,
 639         .get_resync_work = core_get_resync_work,
 640         .set_region_sync = core_set_region_sync,
 641         .get_sync_count = core_get_sync_count,
 642         .status = core_status,
 643 };
 644
 645 static struct dirty_log_type _disk_type = {
 646         .name = "disk",
 647         .module = THIS_MODULE,
 648         .ctr = disk_ctr,
 649         .dtr = disk_dtr,
 650         .suspend = disk_flush,
 651         .resume = disk_resume,
 652         .get_region_size = core_get_region_size,
 653         .is_clean = core_is_clean,
 654         .in_sync = core_in_sync,
 655         .flush = disk_flush,
 656         .mark_region = core_mark_region,
 657         .clear_region = core_clear_region,
 658         .get_resync_work = core_get_resync_work,
 659         .set_region_sync = core_set_region_sync,
 660         .get_sync_count = core_get_sync_count,
 661         .status = disk_status,
 662 };
 663
 664 int __init dm_dirty_log_init(void)
 665 {
 666         int r;
 667
 668         r = dm_register_dirty_log_type(&_core_type);
 669         if (r)
 670                 DMWARN("couldn't register core log");
 671
 672         r = dm_register_dirty_log_type(&_disk_type);
 673         if (r) {
 674                 DMWARN("couldn't register disk type");
 675                 dm_unregister_dirty_log_type(&_core_type);
 676         }
 677
 678         return r;
 679 }
 680
 681 void dm_dirty_log_exit(void)
 682 {
 683         dm_unregister_dirty_log_type(&_disk_type);
 684         dm_unregister_dirty_log_type(&_core_type);
 685 }
 686
 687 EXPORT_SYMBOL(dm_register_dirty_log_type);
 688 EXPORT_SYMBOL(dm_unregister_dirty_log_type);
 689 EXPORT_SYMBOL(dm_create_dirty_log);
 690 EXPORT_SYMBOL(dm_destroy_dirty_log);