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 core_ctr(struct dirty_log *log, struct dm_target *ti,
 248                     unsigned int argc, char **argv)
 249 {
 250         enum sync sync = DEFAULTSYNC;
 251
 252         struct log_c *lc;
 253         uint32_t region_size;
 254         unsigned int region_count;
 255         size_t bitset_size;
 256
 257         if (argc < 1 || argc > 2) {
 258                 DMWARN("wrong number of arguments to mirror log");
 259                 return -EINVAL;
 260         }
 261
 262         if (argc > 1) {
 263                 if (!strcmp(argv[1], "sync"))
 264                         sync = FORCESYNC;
 265                 else if (!strcmp(argv[1], "nosync"))
 266                         sync = NOSYNC;
 267                 else {
 268                         DMWARN("unrecognised sync argument to mirror log: %s",
 269                                argv[1]);
 270                         return -EINVAL;
 271                 }
 272         }
 273
 274         if (sscanf(argv[0], "%u", &region_size) != 1) {
 275                 DMWARN("invalid region size string");
 276                 return -EINVAL;
 277         }
 278
 279         region_count = dm_sector_div_up(ti->len, region_size);
 280
 281         lc = kmalloc(sizeof(*lc), GFP_KERNEL);
 282         if (!lc) {
 283                 DMWARN("couldn't allocate core log");
 284                 return -ENOMEM;
 285         }
 286
 287         lc->ti = ti;
 288         lc->touched = 0;
 289         lc->region_size = region_size;
 290         lc->region_count = region_count;
 291         lc->sync = sync;
 292
 293         /*
 294          * Work out how many "unsigned long"s we need to hold the bitset.
 295          */
 296         bitset_size = dm_round_up(region_count,
 297                                   sizeof(unsigned long) << BYTE_SHIFT);
 298         bitset_size >>= BYTE_SHIFT;
 299
 300         lc->bitset_uint32_count = bitset_size / 4;
 301         lc->clean_bits = vmalloc(bitset_size);
 302         if (!lc->clean_bits) {
 303                 DMWARN("couldn't allocate clean bitset");
 304                 kfree(lc);
 305                 return -ENOMEM;
 306         }
 307         memset(lc->clean_bits, -1, bitset_size);
 308
 309         lc->sync_bits = vmalloc(bitset_size);
 310         if (!lc->sync_bits) {
 311                 DMWARN("couldn't allocate sync bitset");
 312                 vfree(lc->clean_bits);
 313                 kfree(lc);
 314                 return -ENOMEM;
 315         }
 316         memset(lc->sync_bits, (sync == NOSYNC) ? -1 : 0, bitset_size);
 317         lc->sync_count = (sync == NOSYNC) ? region_count : 0;
 318
 319         lc->recovering_bits = vmalloc(bitset_size);
 320         if (!lc->recovering_bits) {
 321                 DMWARN("couldn't allocate sync bitset");
 322                 vfree(lc->sync_bits);
 323                 vfree(lc->clean_bits);
 324                 kfree(lc);
 325                 return -ENOMEM;
 326         }
 327         memset(lc->recovering_bits, 0, bitset_size);
 328         lc->sync_search = 0;
 329         log->context = lc;
 330         return 0;
 331 }
 332
 333 static void core_dtr(struct dirty_log *log)
 334 {
 335         struct log_c *lc = (struct log_c *) log->context;
 336         vfree(lc->clean_bits);
 337         vfree(lc->sync_bits);
 338         vfree(lc->recovering_bits);
 339         kfree(lc);
 340 }
 341
 342 /*----------------------------------------------------------------
 343  * disk log constructor/destructor
 344  *
 345  * argv contains log_device region_size followed optionally by [no]sync
 346  *--------------------------------------------------------------*/
 347 static int disk_ctr(struct dirty_log *log, struct dm_target *ti,
 348                     unsigned int argc, char **argv)
 349 {
 350         int r;
 351         size_t size, bitset_size;
 352         struct log_c *lc;
 353         struct dm_dev *dev;
 354         uint32_t *clean_bits;
 355
 356         if (argc < 2 || argc > 3) {
 357                 DMWARN("wrong number of arguments to disk mirror log");
 358                 return -EINVAL;
 359         }
 360
 361         r = dm_get_device(ti, argv[0], 0, 0 /* FIXME */,
 362                           FMODE_READ | FMODE_WRITE, &dev);
 363         if (r)
 364                 return r;
 365
 366         r = core_ctr(log, ti, argc - 1, argv + 1);
 367         if (r) {
 368                 dm_put_device(ti, dev);
 369                 return r;
 370         }
 371
 372         lc = (struct log_c *) log->context;
 373         lc->log_dev = dev;
 374
 375         /* setup the disk header fields */
 376         lc->header_location.bdev = lc->log_dev->bdev;
 377         lc->header_location.sector = 0;
 378
 379         /* Include both the header and the bitset in one buffer. */
 380         bitset_size = lc->bitset_uint32_count * sizeof(uint32_t);
 381         size = dm_round_up((LOG_OFFSET << SECTOR_SHIFT) + bitset_size,
 382                            ti->limits.hardsect_size);
 383         lc->header_location.count = size >> SECTOR_SHIFT;
 384
 385         lc->disk_header = vmalloc(size);
 386         if (!lc->disk_header)
 387                 goto bad;
 388
 389         /*
 390          * Deallocate the clean_bits buffer that was allocated in core_ctr()
 391          * and point it at the appropriate place in the disk_header buffer.
 392          */
 393         clean_bits = lc->clean_bits;
 394         lc->clean_bits = (void *)lc->disk_header + (LOG_OFFSET << SECTOR_SHIFT);
 395         memcpy(lc->clean_bits, clean_bits, bitset_size);
 396         vfree(clean_bits);
 397
 398         return 0;
 399
 400  bad:
 401         dm_put_device(ti, lc->log_dev);
 402         core_dtr(log);
 403         return -ENOMEM;
 404 }
 405
 406 static void disk_dtr(struct dirty_log *log)
 407 {
 408         struct log_c *lc = (struct log_c *) log->context;
 409         dm_put_device(lc->ti, lc->log_dev);
 410         vfree(lc->disk_header);
 411         lc->clean_bits = NULL;
 412         core_dtr(log);
 413 }
 414
 415 static int count_bits32(uint32_t *addr, unsigned size)
 416 {
 417         int count = 0, i;
 418
 419         for (i = 0; i < size; i++) {
 420                 count += hweight32(*(addr+i));
 421         }
 422         return count;
 423 }
 424
 425 static int disk_resume(struct dirty_log *log)
 426 {
 427         int r;
 428         unsigned i;
 429         struct log_c *lc = (struct log_c *) log->context;
 430         size_t size = lc->bitset_uint32_count * sizeof(uint32_t);
 431
 432         /* read the disk header */
 433         r = read_header(lc);
 434         if (r)
 435                 return r;
 436
 437         /* set or clear any new bits */
 438         if (lc->sync == NOSYNC)
 439                 for (i = lc->header.nr_regions; i < lc->region_count; i++)
 440                         /* FIXME: amazingly inefficient */
 441                         log_set_bit(lc, lc->clean_bits, i);
 442         else
 443                 for (i = lc->header.nr_regions; i < lc->region_count; i++)
 444                         /* FIXME: amazingly inefficient */
 445                         log_clear_bit(lc, lc->clean_bits, i);
 446
 447         /* copy clean across to sync */
 448         memcpy(lc->sync_bits, lc->clean_bits, size);
 449         lc->sync_count = count_bits32(lc->clean_bits, lc->bitset_uint32_count);
 450
 451         /* set the correct number of regions in the header */
 452         lc->header.nr_regions = lc->region_count;
 453
 454         /* write the new header */
 455         return write_header(lc);
 456 }
 457
 458 static uint32_t core_get_region_size(struct dirty_log *log)
 459 {
 460         struct log_c *lc = (struct log_c *) log->context;
 461         return lc->region_size;
 462 }
 463
 464 static int core_is_clean(struct dirty_log *log, region_t region)
 465 {
 466         struct log_c *lc = (struct log_c *) log->context;
 467         return log_test_bit(lc->clean_bits, region);
 468 }
 469
 470 static int core_in_sync(struct dirty_log *log, region_t region, int block)
 471 {
 472         struct log_c *lc = (struct log_c *) log->context;
 473         return log_test_bit(lc->sync_bits, region);
 474 }
 475
 476 static int core_flush(struct dirty_log *log)
 477 {
 478         /* no op */
 479         return 0;
 480 }
 481
 482 static int disk_flush(struct dirty_log *log)
 483 {
 484         int r;
 485         struct log_c *lc = (struct log_c *) log->context;
 486
 487         /* only write if the log has changed */
 488         if (!lc->touched)
 489                 return 0;
 490
 491         r = write_header(lc);
 492         if (!r)
 493                 lc->touched = 0;
 494
 495         return r;
 496 }
 497
 498 static void core_mark_region(struct dirty_log *log, region_t region)
 499 {
 500         struct log_c *lc = (struct log_c *) log->context;
 501         log_clear_bit(lc, lc->clean_bits, region);
 502 }
 503
 504 static void core_clear_region(struct dirty_log *log, region_t region)
 505 {
 506         struct log_c *lc = (struct log_c *) log->context;
 507         log_set_bit(lc, lc->clean_bits, region);
 508 }
 509
 510 static int core_get_resync_work(struct dirty_log *log, region_t *region)
 511 {
 512         struct log_c *lc = (struct log_c *) log->context;
 513
 514         if (lc->sync_search >= lc->region_count)
 515                 return 0;
 516
 517         do {
 518                 *region = ext2_find_next_zero_bit(
 519                                              (unsigned long *) lc->sync_bits,
 520                                              lc->region_count,
 521                                              lc->sync_search);
 522                 lc->sync_search = *region + 1;
 523
 524                 if (*region >= lc->region_count)
 525                         return 0;
 526
 527         } while (log_test_bit(lc->recovering_bits, *region));
 528
 529         log_set_bit(lc, lc->recovering_bits, *region);
 530         return 1;
 531 }
 532
 533 static void core_complete_resync_work(struct dirty_log *log, region_t region,
 534                                       int success)
 535 {
 536         struct log_c *lc = (struct log_c *) log->context;
 537
 538         log_clear_bit(lc, lc->recovering_bits, region);
 539         if (success) {
 540                 log_set_bit(lc, lc->sync_bits, region);
 541                 lc->sync_count++;
 542         }
 543 }
 544
 545 static region_t core_get_sync_count(struct dirty_log *log)
 546 {
 547         struct log_c *lc = (struct log_c *) log->context;
 548
 549         return lc->sync_count;
 550 }
 551
 552 #define DMEMIT_SYNC \
 553         if (lc->sync != DEFAULTSYNC) \
 554                 DMEMIT("%ssync ", lc->sync == NOSYNC ? "no" : "")
 555
 556 static int core_status(struct dirty_log *log, status_type_t status,
 557                        char *result, unsigned int maxlen)
 558 {
 559         int sz = 0;
 560         struct log_c *lc = log->context;
 561
 562         switch(status) {
 563         case STATUSTYPE_INFO:
 564                 break;
 565
 566         case STATUSTYPE_TABLE:
 567                 DMEMIT("%s %u %u ", log->type->name,
 568                        lc->sync == DEFAULTSYNC ? 1 : 2, lc->region_size);
 569                 DMEMIT_SYNC;
 570         }
 571
 572         return sz;
 573 }
 574
 575 static int disk_status(struct dirty_log *log, status_type_t status,
 576                        char *result, unsigned int maxlen)
 577 {
 578         int sz = 0;
 579         char buffer[16];
 580         struct log_c *lc = log->context;
 581
 582         switch(status) {
 583         case STATUSTYPE_INFO:
 584                 break;
 585
 586         case STATUSTYPE_TABLE:
 587                 format_dev_t(buffer, lc->log_dev->bdev->bd_dev);
 588                 DMEMIT("%s %u %s %u ", log->type->name,
 589                        lc->sync == DEFAULTSYNC ? 2 : 3, buffer,
 590                        lc->region_size);
 591                 DMEMIT_SYNC;
 592         }
 593
 594         return sz;
 595 }
 596
 597 static struct dirty_log_type _core_type = {
 598         .name = "core",
 599         .module = THIS_MODULE,
 600         .ctr = core_ctr,
 601         .dtr = core_dtr,
 602         .get_region_size = core_get_region_size,
 603         .is_clean = core_is_clean,
 604         .in_sync = core_in_sync,
 605         .flush = core_flush,
 606         .mark_region = core_mark_region,
 607         .clear_region = core_clear_region,
 608         .get_resync_work = core_get_resync_work,
 609         .complete_resync_work = core_complete_resync_work,
 610         .get_sync_count = core_get_sync_count,
 611         .status = core_status,
 612 };
 613
 614 static struct dirty_log_type _disk_type = {
 615         .name = "disk",
 616         .module = THIS_MODULE,
 617         .ctr = disk_ctr,
 618         .dtr = disk_dtr,
 619         .suspend = disk_flush,
 620         .resume = disk_resume,
 621         .get_region_size = core_get_region_size,
 622         .is_clean = core_is_clean,
 623         .in_sync = core_in_sync,
 624         .flush = disk_flush,
 625         .mark_region = core_mark_region,
 626         .clear_region = core_clear_region,
 627         .get_resync_work = core_get_resync_work,
 628         .complete_resync_work = core_complete_resync_work,
 629         .get_sync_count = core_get_sync_count,
 630         .status = disk_status,
 631 };
 632
 633 int __init dm_dirty_log_init(void)
 634 {
 635         int r;
 636
 637         r = dm_register_dirty_log_type(&_core_type);
 638         if (r)
 639                 DMWARN("couldn't register core log");
 640
 641         r = dm_register_dirty_log_type(&_disk_type);
 642         if (r) {
 643                 DMWARN("couldn't register disk type");
 644                 dm_unregister_dirty_log_type(&_core_type);
 645         }
 646
 647         return r;
 648 }
 649
 650 void dm_dirty_log_exit(void)
 651 {
 652         dm_unregister_dirty_log_type(&_disk_type);
 653         dm_unregister_dirty_log_type(&_core_type);
 654 }
 655
 656 EXPORT_SYMBOL(dm_register_dirty_log_type);
 657 EXPORT_SYMBOL(dm_unregister_dirty_log_type);
 658 EXPORT_SYMBOL(dm_create_dirty_log);
 659 EXPORT_SYMBOL(dm_destroy_dirty_log);