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 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         struct io_region bits_location;
 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  * Bits IO
 245  *--------------------------------------------------------------*/
 246 static int read_bits(struct log_c *log)
 247 {
 248         int r;
 249         unsigned long ebits;
 250
 251         r = dm_io_sync_vm(1, &log->bits_location, READ,
 252                           log->clean_bits, &ebits);
 253         if (r)
 254                 return r;
 255
 256         return 0;
 257 }
 258
 259 static int write_bits(struct log_c *log)
 260 {
 261         unsigned long ebits;
 262         return dm_io_sync_vm(1, &log->bits_location, WRITE,
 263                              log->clean_bits, &ebits);
 264 }
 265
 266 /*----------------------------------------------------------------
 267  * core log constructor/destructor
 268  *
 269  * argv contains region_size followed optionally by [no]sync
 270  *--------------------------------------------------------------*/
 271 #define BYTE_SHIFT 3
 272 static int core_ctr(struct dirty_log *log, struct dm_target *ti,
 273                     unsigned int argc, char **argv)
 274 {
 275         enum sync sync = DEFAULTSYNC;
 276
 277         struct log_c *lc;
 278         uint32_t region_size;
 279         unsigned int region_count;
 280         size_t bitset_size;
 281
 282         if (argc < 1 || argc > 2) {
 283                 DMWARN("wrong number of arguments to mirror log");
 284                 return -EINVAL;
 285         }
 286
 287         if (argc > 1) {
 288                 if (!strcmp(argv[1], "sync"))
 289                         sync = FORCESYNC;
 290                 else if (!strcmp(argv[1], "nosync"))
 291                         sync = NOSYNC;
 292                 else {
 293                         DMWARN("unrecognised sync argument to mirror log: %s",
 294                                argv[1]);
 295                         return -EINVAL;
 296                 }
 297         }
 298
 299         if (sscanf(argv[0], "%u", &region_size) != 1) {
 300                 DMWARN("invalid region size string");
 301                 return -EINVAL;
 302         }
 303
 304         region_count = dm_sector_div_up(ti->len, region_size);
 305
 306         lc = kmalloc(sizeof(*lc), GFP_KERNEL);
 307         if (!lc) {
 308                 DMWARN("couldn't allocate core log");
 309                 return -ENOMEM;
 310         }
 311
 312         lc->ti = ti;
 313         lc->touched = 0;
 314         lc->region_size = region_size;
 315         lc->region_count = region_count;
 316         lc->sync = sync;
 317
 318         /*
 319          * Work out how many "unsigned long"s we need to hold the bitset.
 320          */
 321         bitset_size = dm_round_up(region_count,
 322                                   sizeof(unsigned long) << BYTE_SHIFT);
 323         bitset_size >>= BYTE_SHIFT;
 324
 325         lc->bitset_uint32_count = bitset_size / 4;
 326         lc->clean_bits = vmalloc(bitset_size);
 327         if (!lc->clean_bits) {
 328                 DMWARN("couldn't allocate clean bitset");
 329                 kfree(lc);
 330                 return -ENOMEM;
 331         }
 332         memset(lc->clean_bits, -1, bitset_size);
 333
 334         lc->sync_bits = vmalloc(bitset_size);
 335         if (!lc->sync_bits) {
 336                 DMWARN("couldn't allocate sync bitset");
 337                 vfree(lc->clean_bits);
 338                 kfree(lc);
 339                 return -ENOMEM;
 340         }
 341         memset(lc->sync_bits, (sync == NOSYNC) ? -1 : 0, bitset_size);
 342         lc->sync_count = (sync == NOSYNC) ? region_count : 0;
 343
 344         lc->recovering_bits = vmalloc(bitset_size);
 345         if (!lc->recovering_bits) {
 346                 DMWARN("couldn't allocate sync bitset");
 347                 vfree(lc->sync_bits);
 348                 vfree(lc->clean_bits);
 349                 kfree(lc);
 350                 return -ENOMEM;
 351         }
 352         memset(lc->recovering_bits, 0, bitset_size);
 353         lc->sync_search = 0;
 354         log->context = lc;
 355         return 0;
 356 }
 357
 358 static void core_dtr(struct dirty_log *log)
 359 {
 360         struct log_c *lc = (struct log_c *) log->context;
 361         vfree(lc->clean_bits);
 362         vfree(lc->sync_bits);
 363         vfree(lc->recovering_bits);
 364         kfree(lc);
 365 }
 366
 367 /*----------------------------------------------------------------
 368  * disk log constructor/destructor
 369  *
 370  * argv contains log_device region_size followed optionally by [no]sync
 371  *--------------------------------------------------------------*/
 372 static int disk_ctr(struct dirty_log *log, struct dm_target *ti,
 373                     unsigned int argc, char **argv)
 374 {
 375         int r;
 376         size_t size;
 377         struct log_c *lc;
 378         struct dm_dev *dev;
 379
 380         if (argc < 2 || argc > 3) {
 381                 DMWARN("wrong number of arguments to disk mirror log");
 382                 return -EINVAL;
 383         }
 384
 385         r = dm_get_device(ti, argv[0], 0, 0 /* FIXME */,
 386                           FMODE_READ | FMODE_WRITE, &dev);
 387         if (r)
 388                 return r;
 389
 390         r = core_ctr(log, ti, argc - 1, argv + 1);
 391         if (r) {
 392                 dm_put_device(ti, dev);
 393                 return r;
 394         }
 395
 396         lc = (struct log_c *) log->context;
 397         lc->log_dev = dev;
 398
 399         /* setup the disk header fields */
 400         lc->header_location.bdev = lc->log_dev->bdev;
 401         lc->header_location.sector = 0;
 402         lc->header_location.count = 1;
 403
 404         /*
 405          * We can't read less than this amount, even though we'll
 406          * not be using most of this space.
 407          */
 408         lc->disk_header = vmalloc(1 << SECTOR_SHIFT);
 409         if (!lc->disk_header)
 410                 goto bad;
 411
 412         /* setup the disk bitset fields */
 413         lc->bits_location.bdev = lc->log_dev->bdev;
 414         lc->bits_location.sector = LOG_OFFSET;
 415
 416         size = dm_round_up(lc->bitset_uint32_count * sizeof(uint32_t),
 417                            1 << SECTOR_SHIFT);
 418         lc->bits_location.count = size >> SECTOR_SHIFT;
 419         return 0;
 420
 421  bad:
 422         dm_put_device(ti, lc->log_dev);
 423         core_dtr(log);
 424         return -ENOMEM;
 425 }
 426
 427 static void disk_dtr(struct dirty_log *log)
 428 {
 429         struct log_c *lc = (struct log_c *) log->context;
 430         dm_put_device(lc->ti, lc->log_dev);
 431         vfree(lc->disk_header);
 432         core_dtr(log);
 433 }
 434
 435 static int count_bits32(uint32_t *addr, unsigned size)
 436 {
 437         int count = 0, i;
 438
 439         for (i = 0; i < size; i++) {
 440                 count += hweight32(*(addr+i));
 441         }
 442         return count;
 443 }
 444
 445 static int disk_resume(struct dirty_log *log)
 446 {
 447         int r;
 448         unsigned i;
 449         struct log_c *lc = (struct log_c *) log->context;
 450         size_t size = lc->bitset_uint32_count * sizeof(uint32_t);
 451
 452         /* read the disk header */
 453         r = read_header(lc);
 454         if (r)
 455                 return r;
 456
 457         /* read the bits */
 458         r = read_bits(lc);
 459         if (r)
 460                 return r;
 461
 462         /* set or clear any new bits */
 463         if (lc->sync == NOSYNC)
 464                 for (i = lc->header.nr_regions; i < lc->region_count; i++)
 465                         /* FIXME: amazingly inefficient */
 466                         log_set_bit(lc, lc->clean_bits, i);
 467         else
 468                 for (i = lc->header.nr_regions; i < lc->region_count; i++)
 469                         /* FIXME: amazingly inefficient */
 470                         log_clear_bit(lc, lc->clean_bits, i);
 471
 472         /* copy clean across to sync */
 473         memcpy(lc->sync_bits, lc->clean_bits, size);
 474         lc->sync_count = count_bits32(lc->clean_bits, lc->bitset_uint32_count);
 475
 476         /* write the bits */
 477         r = write_bits(lc);
 478         if (r)
 479                 return r;
 480
 481         /* set the correct number of regions in the header */
 482         lc->header.nr_regions = lc->region_count;
 483
 484         /* write the new header */
 485         return write_header(lc);
 486 }
 487
 488 static uint32_t core_get_region_size(struct dirty_log *log)
 489 {
 490         struct log_c *lc = (struct log_c *) log->context;
 491         return lc->region_size;
 492 }
 493
 494 static int core_is_clean(struct dirty_log *log, region_t region)
 495 {
 496         struct log_c *lc = (struct log_c *) log->context;
 497         return log_test_bit(lc->clean_bits, region);
 498 }
 499
 500 static int core_in_sync(struct dirty_log *log, region_t region, int block)
 501 {
 502         struct log_c *lc = (struct log_c *) log->context;
 503         return log_test_bit(lc->sync_bits, region);
 504 }
 505
 506 static int core_flush(struct dirty_log *log)
 507 {
 508         /* no op */
 509         return 0;
 510 }
 511
 512 static int disk_flush(struct dirty_log *log)
 513 {
 514         int r;
 515         struct log_c *lc = (struct log_c *) log->context;
 516
 517         /* only write if the log has changed */
 518         if (!lc->touched)
 519                 return 0;
 520
 521         r = write_bits(lc);
 522         if (!r)
 523                 lc->touched = 0;
 524
 525         return r;
 526 }
 527
 528 static void core_mark_region(struct dirty_log *log, region_t region)
 529 {
 530         struct log_c *lc = (struct log_c *) log->context;
 531         log_clear_bit(lc, lc->clean_bits, region);
 532 }
 533
 534 static void core_clear_region(struct dirty_log *log, region_t region)
 535 {
 536         struct log_c *lc = (struct log_c *) log->context;
 537         log_set_bit(lc, lc->clean_bits, region);
 538 }
 539
 540 static int core_get_resync_work(struct dirty_log *log, region_t *region)
 541 {
 542         struct log_c *lc = (struct log_c *) log->context;
 543
 544         if (lc->sync_search >= lc->region_count)
 545                 return 0;
 546
 547         do {
 548                 *region = ext2_find_next_zero_bit(
 549                                              (unsigned long *) lc->sync_bits,
 550                                              lc->region_count,
 551                                              lc->sync_search);
 552                 lc->sync_search = *region + 1;
 553
 554                 if (*region >= lc->region_count)
 555                         return 0;
 556
 557         } while (log_test_bit(lc->recovering_bits, *region));
 558
 559         log_set_bit(lc, lc->recovering_bits, *region);
 560         return 1;
 561 }
 562
 563 static void core_complete_resync_work(struct dirty_log *log, region_t region,
 564                                       int success)
 565 {
 566         struct log_c *lc = (struct log_c *) log->context;
 567
 568         log_clear_bit(lc, lc->recovering_bits, region);
 569         if (success) {
 570                 log_set_bit(lc, lc->sync_bits, region);
 571                 lc->sync_count++;
 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         .get_region_size = core_get_region_size,
 633         .is_clean = core_is_clean,
 634         .in_sync = core_in_sync,
 635         .flush = core_flush,
 636         .mark_region = core_mark_region,
 637         .clear_region = core_clear_region,
 638         .get_resync_work = core_get_resync_work,
 639         .complete_resync_work = core_complete_resync_work,
 640         .get_sync_count = core_get_sync_count,
 641         .status = core_status,
 642 };
 643
 644 static struct dirty_log_type _disk_type = {
 645         .name = "disk",
 646         .module = THIS_MODULE,
 647         .ctr = disk_ctr,
 648         .dtr = disk_dtr,
 649         .suspend = disk_flush,
 650         .resume = disk_resume,
 651         .get_region_size = core_get_region_size,
 652         .is_clean = core_is_clean,
 653         .in_sync = core_in_sync,
 654         .flush = disk_flush,
 655         .mark_region = core_mark_region,
 656         .clear_region = core_clear_region,
 657         .get_resync_work = core_get_resync_work,
 658         .complete_resync_work = core_complete_resync_work,
 659         .get_sync_count = core_get_sync_count,
 660         .status = disk_status,
 661 };
 662
 663 int __init dm_dirty_log_init(void)
 664 {
 665         int r;
 666
 667         r = dm_register_dirty_log_type(&_core_type);
 668         if (r)
 669                 DMWARN("couldn't register core log");
 670
 671         r = dm_register_dirty_log_type(&_disk_type);
 672         if (r) {
 673                 DMWARN("couldn't register disk type");
 674                 dm_unregister_dirty_log_type(&_core_type);
 675         }
 676
 677         return r;
 678 }
 679
 680 void dm_dirty_log_exit(void)
 681 {
 682         dm_unregister_dirty_log_type(&_disk_type);
 683         dm_unregister_dirty_log_type(&_core_type);
 684 }
 685
 686 EXPORT_SYMBOL(dm_register_dirty_log_type);
 687 EXPORT_SYMBOL(dm_unregister_dirty_log_type);
 688 EXPORT_SYMBOL(dm_create_dirty_log);
 689 EXPORT_SYMBOL(dm_destroy_dirty_log);