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