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 1
 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         uint32_t *disk_bits;
 161 };
 162
 163 /*
 164  * The touched member needs to be updated every time we access
 165  * one of the bitsets.
 166  */
 167 static  inline int log_test_bit(uint32_t *bs, unsigned bit)
 168 {
 169         return test_bit(bit, (unsigned long *) bs) ? 1 : 0;
 170 }
 171
 172 static inline void log_set_bit(struct log_c *l,
 173                                uint32_t *bs, unsigned bit)
 174 {
 175         set_bit(bit, (unsigned long *) bs);
 176         l->touched = 1;
 177 }
 178
 179 static inline void log_clear_bit(struct log_c *l,
 180                                  uint32_t *bs, unsigned bit)
 181 {
 182         clear_bit(bit, (unsigned long *) bs);
 183         l->touched = 1;
 184 }
 185
 186 /*----------------------------------------------------------------
 187  * Header IO
 188  *--------------------------------------------------------------*/
 189 static void header_to_disk(struct log_header *core, struct log_header *disk)
 190 {
 191         disk->magic = cpu_to_le32(core->magic);
 192         disk->version = cpu_to_le32(core->version);
 193         disk->nr_regions = cpu_to_le64(core->nr_regions);
 194 }
 195
 196 static void header_from_disk(struct log_header *core, struct log_header *disk)
 197 {
 198         core->magic = le32_to_cpu(disk->magic);
 199         core->version = le32_to_cpu(disk->version);
 200         core->nr_regions = le64_to_cpu(disk->nr_regions);
 201 }
 202
 203 static int read_header(struct log_c *log)
 204 {
 205         int r;
 206         unsigned long ebits;
 207
 208         r = dm_io_sync_vm(1, &log->header_location, READ,
 209                           log->disk_header, &ebits);
 210         if (r)
 211                 return r;
 212
 213         header_from_disk(&log->header, log->disk_header);
 214
 215         /* New log required? */
 216         if (log->sync != DEFAULTSYNC || log->header.magic != MIRROR_MAGIC) {
 217                 log->header.magic = MIRROR_MAGIC;
 218                 log->header.version = MIRROR_DISK_VERSION;
 219                 log->header.nr_regions = 0;
 220         }
 221
 222         if (log->header.version != MIRROR_DISK_VERSION) {
 223                 DMWARN("incompatible disk log version");
 224                 return -EINVAL;
 225         }
 226
 227         return 0;
 228 }
 229
 230 static inline int write_header(struct log_c *log)
 231 {
 232         unsigned long ebits;
 233
 234         header_to_disk(&log->header, log->disk_header);
 235         return dm_io_sync_vm(1, &log->header_location, WRITE,
 236                              log->disk_header, &ebits);
 237 }
 238
 239 /*----------------------------------------------------------------
 240  * Bits IO
 241  *--------------------------------------------------------------*/
 242 static inline void bits_to_core(uint32_t *core, uint32_t *disk, unsigned count)
 243 {
 244         unsigned i;
 245
 246         for (i = 0; i < count; i++)
 247                 core[i] = le32_to_cpu(disk[i]);
 248 }
 249
 250 static inline void bits_to_disk(uint32_t *core, uint32_t *disk, unsigned count)
 251 {
 252         unsigned i;
 253
 254         /* copy across the clean/dirty bitset */
 255         for (i = 0; i < count; i++)
 256                 disk[i] = cpu_to_le32(core[i]);
 257 }
 258
 259 static int read_bits(struct log_c *log)
 260 {
 261         int r;
 262         unsigned long ebits;
 263
 264         r = dm_io_sync_vm(1, &log->bits_location, READ,
 265                           log->disk_bits, &ebits);
 266         if (r)
 267                 return r;
 268
 269         bits_to_core(log->clean_bits, log->disk_bits,
 270                      log->bitset_uint32_count);
 271         return 0;
 272 }
 273
 274 static int write_bits(struct log_c *log)
 275 {
 276         unsigned long ebits;
 277         bits_to_disk(log->clean_bits, log->disk_bits,
 278                      log->bitset_uint32_count);
 279         return dm_io_sync_vm(1, &log->bits_location, WRITE,
 280                              log->disk_bits, &ebits);
 281 }
 282
 283 /*----------------------------------------------------------------
 284  * core log constructor/destructor
 285  *
 286  * argv contains region_size followed optionally by [no]sync
 287  *--------------------------------------------------------------*/
 288 #define BYTE_SHIFT 3
 289 static int core_ctr(struct dirty_log *log, struct dm_target *ti,
 290                     unsigned int argc, char **argv)
 291 {
 292         enum sync sync = DEFAULTSYNC;
 293
 294         struct log_c *lc;
 295         uint32_t region_size;
 296         unsigned int region_count;
 297         size_t bitset_size;
 298
 299         if (argc < 1 || argc > 2) {
 300                 DMWARN("wrong number of arguments to mirror log");
 301                 return -EINVAL;
 302         }
 303
 304         if (argc > 1) {
 305                 if (!strcmp(argv[1], "sync"))
 306                         sync = FORCESYNC;
 307                 else if (!strcmp(argv[1], "nosync"))
 308                         sync = NOSYNC;
 309                 else {
 310                         DMWARN("unrecognised sync argument to mirror log: %s",
 311                                argv[1]);
 312                         return -EINVAL;
 313                 }
 314         }
 315
 316         if (sscanf(argv[0], "%u", &region_size) != 1) {
 317                 DMWARN("invalid region size string");
 318                 return -EINVAL;
 319         }
 320
 321         region_count = dm_sector_div_up(ti->len, region_size);
 322
 323         lc = kmalloc(sizeof(*lc), GFP_KERNEL);
 324         if (!lc) {
 325                 DMWARN("couldn't allocate core log");
 326                 return -ENOMEM;
 327         }
 328
 329         lc->ti = ti;
 330         lc->touched = 0;
 331         lc->region_size = region_size;
 332         lc->region_count = region_count;
 333         lc->sync = sync;
 334
 335         /*
 336          * Work out how many "unsigned long"s we need to hold the bitset.
 337          */
 338         bitset_size = dm_round_up(region_count,
 339                                   sizeof(unsigned long) << BYTE_SHIFT);
 340         bitset_size >>= BYTE_SHIFT;
 341
 342         lc->bitset_uint32_count = bitset_size / 4;
 343         lc->clean_bits = vmalloc(bitset_size);
 344         if (!lc->clean_bits) {
 345                 DMWARN("couldn't allocate clean bitset");
 346                 kfree(lc);
 347                 return -ENOMEM;
 348         }
 349         memset(lc->clean_bits, -1, bitset_size);
 350
 351         lc->sync_bits = vmalloc(bitset_size);
 352         if (!lc->sync_bits) {
 353                 DMWARN("couldn't allocate sync bitset");
 354                 vfree(lc->clean_bits);
 355                 kfree(lc);
 356                 return -ENOMEM;
 357         }
 358         memset(lc->sync_bits, (sync == NOSYNC) ? -1 : 0, bitset_size);
 359         lc->sync_count = (sync == NOSYNC) ? region_count : 0;
 360
 361         lc->recovering_bits = vmalloc(bitset_size);
 362         if (!lc->recovering_bits) {
 363                 DMWARN("couldn't allocate sync bitset");
 364                 vfree(lc->sync_bits);
 365                 vfree(lc->clean_bits);
 366                 kfree(lc);
 367                 return -ENOMEM;
 368         }
 369         memset(lc->recovering_bits, 0, bitset_size);
 370         lc->sync_search = 0;
 371         log->context = lc;
 372         return 0;
 373 }
 374
 375 static void core_dtr(struct dirty_log *log)
 376 {
 377         struct log_c *lc = (struct log_c *) log->context;
 378         vfree(lc->clean_bits);
 379         vfree(lc->sync_bits);
 380         vfree(lc->recovering_bits);
 381         kfree(lc);
 382 }
 383
 384 /*----------------------------------------------------------------
 385  * disk log constructor/destructor
 386  *
 387  * argv contains log_device region_size followed optionally by [no]sync
 388  *--------------------------------------------------------------*/
 389 static int disk_ctr(struct dirty_log *log, struct dm_target *ti,
 390                     unsigned int argc, char **argv)
 391 {
 392         int r;
 393         size_t size;
 394         struct log_c *lc;
 395         struct dm_dev *dev;
 396
 397         if (argc < 2 || argc > 3) {
 398                 DMWARN("wrong number of arguments to disk mirror log");
 399                 return -EINVAL;
 400         }
 401
 402         r = dm_get_device(ti, argv[0], 0, 0 /* FIXME */,
 403                           FMODE_READ | FMODE_WRITE, &dev);
 404         if (r)
 405                 return r;
 406
 407         r = core_ctr(log, ti, argc - 1, argv + 1);
 408         if (r) {
 409                 dm_put_device(ti, dev);
 410                 return r;
 411         }
 412
 413         lc = (struct log_c *) log->context;
 414         lc->log_dev = dev;
 415
 416         /* setup the disk header fields */
 417         lc->header_location.bdev = lc->log_dev->bdev;
 418         lc->header_location.sector = 0;
 419         lc->header_location.count = 1;
 420
 421         /*
 422          * We can't read less than this amount, even though we'll
 423          * not be using most of this space.
 424          */
 425         lc->disk_header = vmalloc(1 << SECTOR_SHIFT);
 426         if (!lc->disk_header)
 427                 goto bad;
 428
 429         /* setup the disk bitset fields */
 430         lc->bits_location.bdev = lc->log_dev->bdev;
 431         lc->bits_location.sector = LOG_OFFSET;
 432
 433         size = dm_round_up(lc->bitset_uint32_count * sizeof(uint32_t),
 434                            1 << SECTOR_SHIFT);
 435         lc->bits_location.count = size >> SECTOR_SHIFT;
 436         lc->disk_bits = vmalloc(size);
 437         if (!lc->disk_bits) {
 438                 vfree(lc->disk_header);
 439                 goto bad;
 440         }
 441         return 0;
 442
 443  bad:
 444         dm_put_device(ti, lc->log_dev);
 445         core_dtr(log);
 446         return -ENOMEM;
 447 }
 448
 449 static void disk_dtr(struct dirty_log *log)
 450 {
 451         struct log_c *lc = (struct log_c *) log->context;
 452         dm_put_device(lc->ti, lc->log_dev);
 453         vfree(lc->disk_header);
 454         vfree(lc->disk_bits);
 455         core_dtr(log);
 456 }
 457
 458 static int count_bits32(uint32_t *addr, unsigned size)
 459 {
 460         int count = 0, i;
 461
 462         for (i = 0; i < size; i++) {
 463                 count += hweight32(*(addr+i));
 464         }
 465         return count;
 466 }
 467
 468 static int disk_resume(struct dirty_log *log)
 469 {
 470         int r;
 471         unsigned i;
 472         struct log_c *lc = (struct log_c *) log->context;
 473         size_t size = lc->bitset_uint32_count * sizeof(uint32_t);
 474
 475         /* read the disk header */
 476         r = read_header(lc);
 477         if (r)
 478                 return r;
 479
 480         /* read the bits */
 481         r = read_bits(lc);
 482         if (r)
 483                 return r;
 484
 485         /* set or clear any new bits */
 486         if (lc->sync == NOSYNC)
 487                 for (i = lc->header.nr_regions; i < lc->region_count; i++)
 488                         /* FIXME: amazingly inefficient */
 489                         log_set_bit(lc, lc->clean_bits, i);
 490         else
 491                 for (i = lc->header.nr_regions; i < lc->region_count; i++)
 492                         /* FIXME: amazingly inefficient */
 493                         log_clear_bit(lc, lc->clean_bits, i);
 494
 495         /* copy clean across to sync */
 496         memcpy(lc->sync_bits, lc->clean_bits, size);
 497         lc->sync_count = count_bits32(lc->clean_bits, lc->bitset_uint32_count);
 498
 499         /* write the bits */
 500         r = write_bits(lc);
 501         if (r)
 502                 return r;
 503
 504         /* set the correct number of regions in the header */
 505         lc->header.nr_regions = lc->region_count;
 506
 507         /* write the new header */
 508         return write_header(lc);
 509 }
 510
 511 static uint32_t core_get_region_size(struct dirty_log *log)
 512 {
 513         struct log_c *lc = (struct log_c *) log->context;
 514         return lc->region_size;
 515 }
 516
 517 static int core_is_clean(struct dirty_log *log, region_t region)
 518 {
 519         struct log_c *lc = (struct log_c *) log->context;
 520         return log_test_bit(lc->clean_bits, region);
 521 }
 522
 523 static int core_in_sync(struct dirty_log *log, region_t region, int block)
 524 {
 525         struct log_c *lc = (struct log_c *) log->context;
 526         return log_test_bit(lc->sync_bits, region);
 527 }
 528
 529 static int core_flush(struct dirty_log *log)
 530 {
 531         /* no op */
 532         return 0;
 533 }
 534
 535 static int disk_flush(struct dirty_log *log)
 536 {
 537         int r;
 538         struct log_c *lc = (struct log_c *) log->context;
 539
 540         /* only write if the log has changed */
 541         if (!lc->touched)
 542                 return 0;
 543
 544         r = write_bits(lc);
 545         if (!r)
 546                 lc->touched = 0;
 547
 548         return r;
 549 }
 550
 551 static void core_mark_region(struct dirty_log *log, region_t region)
 552 {
 553         struct log_c *lc = (struct log_c *) log->context;
 554         log_clear_bit(lc, lc->clean_bits, region);
 555 }
 556
 557 static void core_clear_region(struct dirty_log *log, region_t region)
 558 {
 559         struct log_c *lc = (struct log_c *) log->context;
 560         log_set_bit(lc, lc->clean_bits, region);
 561 }
 562
 563 static int core_get_resync_work(struct dirty_log *log, region_t *region)
 564 {
 565         struct log_c *lc = (struct log_c *) log->context;
 566
 567         if (lc->sync_search >= lc->region_count)
 568                 return 0;
 569
 570         do {
 571                 *region = find_next_zero_bit((unsigned long *) lc->sync_bits,
 572                                              lc->region_count,
 573                                              lc->sync_search);
 574                 lc->sync_search = *region + 1;
 575
 576                 if (*region == lc->region_count)
 577                         return 0;
 578
 579         } while (log_test_bit(lc->recovering_bits, *region));
 580
 581         log_set_bit(lc, lc->recovering_bits, *region);
 582         return 1;
 583 }
 584
 585 static void core_complete_resync_work(struct dirty_log *log, region_t region,
 586                                       int success)
 587 {
 588         struct log_c *lc = (struct log_c *) log->context;
 589
 590         log_clear_bit(lc, lc->recovering_bits, region);
 591         if (success) {
 592                 log_set_bit(lc, lc->sync_bits, region);
 593                 lc->sync_count++;
 594         }
 595 }
 596
 597 static region_t core_get_sync_count(struct dirty_log *log)
 598 {
 599         struct log_c *lc = (struct log_c *) log->context;
 600
 601         return lc->sync_count;
 602 }
 603
 604 #define DMEMIT_SYNC \
 605         if (lc->sync != DEFAULTSYNC) \
 606                 DMEMIT("%ssync ", lc->sync == NOSYNC ? "no" : "")
 607
 608 static int core_status(struct dirty_log *log, status_type_t status,
 609                        char *result, unsigned int maxlen)
 610 {
 611         int sz = 0;
 612         struct log_c *lc = log->context;
 613
 614         switch(status) {
 615         case STATUSTYPE_INFO:
 616                 break;
 617
 618         case STATUSTYPE_TABLE:
 619                 DMEMIT("%s %u %u ", log->type->name,
 620                        lc->sync == DEFAULTSYNC ? 1 : 2, lc->region_size);
 621                 DMEMIT_SYNC;
 622         }
 623
 624         return sz;
 625 }
 626
 627 static int disk_status(struct dirty_log *log, status_type_t status,
 628                        char *result, unsigned int maxlen)
 629 {
 630         int sz = 0;
 631         char buffer[16];
 632         struct log_c *lc = log->context;
 633
 634         switch(status) {
 635         case STATUSTYPE_INFO:
 636                 break;
 637
 638         case STATUSTYPE_TABLE:
 639                 format_dev_t(buffer, lc->log_dev->bdev->bd_dev);
 640                 DMEMIT("%s %u %s %u ", log->type->name,
 641                        lc->sync == DEFAULTSYNC ? 2 : 3, buffer,
 642                        lc->region_size);
 643                 DMEMIT_SYNC;
 644         }
 645
 646         return sz;
 647 }
 648
 649 static struct dirty_log_type _core_type = {
 650         .name = "core",
 651         .module = THIS_MODULE,
 652         .ctr = core_ctr,
 653         .dtr = core_dtr,
 654         .get_region_size = core_get_region_size,
 655         .is_clean = core_is_clean,
 656         .in_sync = core_in_sync,
 657         .flush = core_flush,
 658         .mark_region = core_mark_region,
 659         .clear_region = core_clear_region,
 660         .get_resync_work = core_get_resync_work,
 661         .complete_resync_work = core_complete_resync_work,
 662         .get_sync_count = core_get_sync_count,
 663         .status = core_status,
 664 };
 665
 666 static struct dirty_log_type _disk_type = {
 667         .name = "disk",
 668         .module = THIS_MODULE,
 669         .ctr = disk_ctr,
 670         .dtr = disk_dtr,
 671         .suspend = disk_flush,
 672         .resume = disk_resume,
 673         .get_region_size = core_get_region_size,
 674         .is_clean = core_is_clean,
 675         .in_sync = core_in_sync,
 676         .flush = disk_flush,
 677         .mark_region = core_mark_region,
 678         .clear_region = core_clear_region,
 679         .get_resync_work = core_get_resync_work,
 680         .complete_resync_work = core_complete_resync_work,
 681         .get_sync_count = core_get_sync_count,
 682         .status = disk_status,
 683 };
 684
 685 int __init dm_dirty_log_init(void)
 686 {
 687         int r;
 688
 689         r = dm_register_dirty_log_type(&_core_type);
 690         if (r)
 691                 DMWARN("couldn't register core log");
 692
 693         r = dm_register_dirty_log_type(&_disk_type);
 694         if (r) {
 695                 DMWARN("couldn't register disk type");
 696                 dm_unregister_dirty_log_type(&_core_type);
 697         }
 698
 699         return r;
 700 }
 701
 702 void dm_dirty_log_exit(void)
 703 {
 704         dm_unregister_dirty_log_type(&_disk_type);
 705         dm_unregister_dirty_log_type(&_core_type);
 706 }
 707
 708 EXPORT_SYMBOL(dm_register_dirty_log_type);
 709 EXPORT_SYMBOL(dm_unregister_dirty_log_type);
 710 EXPORT_SYMBOL(dm_create_dirty_log);
 711 EXPORT_SYMBOL(dm_destroy_dirty_log);