block/qcow2-bitmap.c

   1 /*
   2  * Bitmaps for the QCOW version 2 format
   3  *
   4  * Copyright (c) 2014-2017 Vladimir Sementsov-Ogievskiy
   5  *
   6  * This file is derived from qcow2-snapshot.c, original copyright:
   7  * Copyright (c) 2004-2006 Fabrice Bellard
   8  *
   9  * Permission is hereby granted, free of charge, to any person obtaining a copy
  10  * of this software and associated documentation files (the "Software"), to deal
  11  * in the Software without restriction, including without limitation the rights
  12  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  13  * copies of the Software, and to permit persons to whom the Software is
  14  * furnished to do so, subject to the following conditions:
  15  *
  16  * The above copyright notice and this permission notice shall be included in
  17  * all copies or substantial portions of the Software.
  18  *
  19  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  20  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  21  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  22  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  23  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  24  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  25  * THE SOFTWARE.
  26  */
  27
  28 #include "qemu/osdep.h"
  29 #include "qapi/error.h"
  30 #include "qemu/cutils.h"
  31
  32 #include "block/block_int.h"
  33 #include "qcow2.h"
  34
  35 /* NOTICE: BME here means Bitmaps Extension and used as a namespace for
  36  * _internal_ constants. Please do not use this _internal_ abbreviation for
  37  * other needs and/or outside of this file. */
  38
  39 /* Bitmap directory entry constraints */
  40 #define BME_MAX_TABLE_SIZE 0x8000000
  41 #define BME_MAX_PHYS_SIZE 0x20000000 /* restrict BdrvDirtyBitmap size in RAM */
  42 #define BME_MAX_GRANULARITY_BITS 31
  43 #define BME_MIN_GRANULARITY_BITS 9
  44 #define BME_MAX_NAME_SIZE 1023
  45
  46 #if BME_MAX_TABLE_SIZE * 8ULL > INT_MAX
  47 #error In the code bitmap table physical size assumed to fit into int
  48 #endif
  49
  50 /* Bitmap directory entry flags */
  51 #define BME_RESERVED_FLAGS 0xfffffffcU
  52 #define BME_FLAG_IN_USE (1U << 0)
  53 #define BME_FLAG_AUTO   (1U << 1)
  54
  55 /* bits [1, 8] U [56, 63] are reserved */
  56 #define BME_TABLE_ENTRY_RESERVED_MASK 0xff000000000001feULL
  57 #define BME_TABLE_ENTRY_OFFSET_MASK 0x00fffffffffffe00ULL
  58 #define BME_TABLE_ENTRY_FLAG_ALL_ONES (1ULL << 0)
  59
  60 typedef struct QEMU_PACKED Qcow2BitmapDirEntry {
  61     /* header is 8 byte aligned */
  62     uint64_t bitmap_table_offset;
  63
  64     uint32_t bitmap_table_size;
  65     uint32_t flags;
  66
  67     uint8_t type;
  68     uint8_t granularity_bits;
  69     uint16_t name_size;
  70     uint32_t extra_data_size;
  71     /* extra data follows  */
  72     /* name follows  */
  73 } Qcow2BitmapDirEntry;
  74
  75 typedef struct Qcow2BitmapTable {
  76     uint64_t offset;
  77     uint32_t size; /* number of 64bit entries */
  78     QSIMPLEQ_ENTRY(Qcow2BitmapTable) entry;
  79 } Qcow2BitmapTable;
  80
  81 typedef struct Qcow2Bitmap {
  82     Qcow2BitmapTable table;
  83     uint32_t flags;
  84     uint8_t granularity_bits;
  85     char *name;
  86
  87     BdrvDirtyBitmap *dirty_bitmap;
  88
  89     QSIMPLEQ_ENTRY(Qcow2Bitmap) entry;
  90 } Qcow2Bitmap;
  91 typedef QSIMPLEQ_HEAD(Qcow2BitmapList, Qcow2Bitmap) Qcow2BitmapList;
  92
  93 typedef enum BitmapType {
  94     BT_DIRTY_TRACKING_BITMAP = 1
  95 } BitmapType;
  96
  97 static inline bool can_write(BlockDriverState *bs)
  98 {
  99     return !bdrv_is_read_only(bs) && !(bdrv_get_flags(bs) & BDRV_O_INACTIVE);
 100 }
 101
 102 static int update_header_sync(BlockDriverState *bs)
 103 {
 104     int ret;
 105
 106     ret = qcow2_update_header(bs);
 107     if (ret < 0) {
 108         return ret;
 109     }
 110
 111     return bdrv_flush(bs->file->bs);
 112 }
 113
 114 static inline void bitmap_table_to_be(uint64_t *bitmap_table, size_t size)
 115 {
 116     size_t i;
 117
 118     for (i = 0; i < size; ++i) {
 119         bitmap_table[i] = cpu_to_be64(bitmap_table[i]);
 120     }
 121 }
 122
 123 static int check_table_entry(uint64_t entry, int cluster_size)
 124 {
 125     uint64_t offset;
 126
 127     if (entry & BME_TABLE_ENTRY_RESERVED_MASK) {
 128         return -EINVAL;
 129     }
 130
 131     offset = entry & BME_TABLE_ENTRY_OFFSET_MASK;
 132     if (offset != 0) {
 133         /* if offset specified, bit 0 is reserved */
 134         if (entry & BME_TABLE_ENTRY_FLAG_ALL_ONES) {
 135             return -EINVAL;
 136         }
 137
 138         if (offset % cluster_size != 0) {
 139             return -EINVAL;
 140         }
 141     }
 142
 143     return 0;
 144 }
 145
 146 static int check_constraints_on_bitmap(BlockDriverState *bs,
 147                                        const char *name,
 148                                        uint32_t granularity,
 149                                        Error **errp)
 150 {
 151     BDRVQcow2State *s = bs->opaque;
 152     int granularity_bits = ctz32(granularity);
 153     int64_t len = bdrv_getlength(bs);
 154
 155     assert(granularity > 0);
 156     assert((granularity & (granularity - 1)) == 0);
 157
 158     if (len < 0) {
 159         error_setg_errno(errp, -len, "Failed to get size of '%s'",
 160                          bdrv_get_device_or_node_name(bs));
 161         return len;
 162     }
 163
 164     if (granularity_bits > BME_MAX_GRANULARITY_BITS) {
 165         error_setg(errp, "Granularity exceeds maximum (%llu bytes)",
 166                    1ULL << BME_MAX_GRANULARITY_BITS);
 167         return -EINVAL;
 168     }
 169     if (granularity_bits < BME_MIN_GRANULARITY_BITS) {
 170         error_setg(errp, "Granularity is under minimum (%llu bytes)",
 171                    1ULL << BME_MIN_GRANULARITY_BITS);
 172         return -EINVAL;
 173     }
 174
 175     if ((len > (uint64_t)BME_MAX_PHYS_SIZE << granularity_bits) ||
 176         (len > (uint64_t)BME_MAX_TABLE_SIZE * s->cluster_size <<
 177                granularity_bits))
 178     {
 179         error_setg(errp, "Too much space will be occupied by the bitmap. "
 180                    "Use larger granularity");
 181         return -EINVAL;
 182     }
 183
 184     if (strlen(name) > BME_MAX_NAME_SIZE) {
 185         error_setg(errp, "Name length exceeds maximum (%u characters)",
 186                    BME_MAX_NAME_SIZE);
 187         return -EINVAL;
 188     }
 189
 190     return 0;
 191 }
 192
 193 static void clear_bitmap_table(BlockDriverState *bs, uint64_t *bitmap_table,
 194                                uint32_t bitmap_table_size)
 195 {
 196     BDRVQcow2State *s = bs->opaque;
 197     int i;
 198
 199     for (i = 0; i < bitmap_table_size; ++i) {
 200         uint64_t addr = bitmap_table[i] & BME_TABLE_ENTRY_OFFSET_MASK;
 201         if (!addr) {
 202             continue;
 203         }
 204
 205         qcow2_free_clusters(bs, addr, s->cluster_size, QCOW2_DISCARD_OTHER);
 206         bitmap_table[i] = 0;
 207     }
 208 }
 209
 210 static int bitmap_table_load(BlockDriverState *bs, Qcow2BitmapTable *tb,
 211                              uint64_t **bitmap_table)
 212 {
 213     int ret;
 214     BDRVQcow2State *s = bs->opaque;
 215     uint32_t i;
 216     uint64_t *table;
 217
 218     assert(tb->size != 0);
 219     table = g_try_new(uint64_t, tb->size);
 220     if (table == NULL) {
 221         return -ENOMEM;
 222     }
 223
 224     assert(tb->size <= BME_MAX_TABLE_SIZE);
 225     ret = bdrv_pread(bs->file, tb->offset,
 226                      table, tb->size * sizeof(uint64_t));
 227     if (ret < 0) {
 228         goto fail;
 229     }
 230
 231     for (i = 0; i < tb->size; ++i) {
 232         table[i] = be64_to_cpu(table[i]);
 233         ret = check_table_entry(table[i], s->cluster_size);
 234         if (ret < 0) {
 235             goto fail;
 236         }
 237     }
 238
 239     *bitmap_table = table;
 240     return 0;
 241
 242 fail:
 243     g_free(table);
 244
 245     return ret;
 246 }
 247
 248 static int free_bitmap_clusters(BlockDriverState *bs, Qcow2BitmapTable *tb)
 249 {
 250     int ret;
 251     uint64_t *bitmap_table;
 252
 253     ret = bitmap_table_load(bs, tb, &bitmap_table);
 254     if (ret < 0) {
 255         return ret;
 256     }
 257
 258     clear_bitmap_table(bs, bitmap_table, tb->size);
 259     qcow2_free_clusters(bs, tb->offset, tb->size * sizeof(uint64_t),
 260                         QCOW2_DISCARD_OTHER);
 261     g_free(bitmap_table);
 262
 263     tb->offset = 0;
 264     tb->size = 0;
 265
 266     return 0;
 267 }
 268
 269 /* Return the disk size covered by a single qcow2 cluster of bitmap data. */
 270 static uint64_t bytes_covered_by_bitmap_cluster(const BDRVQcow2State *s,
 271                                                 const BdrvDirtyBitmap *bitmap)
 272 {
 273     uint64_t granularity = bdrv_dirty_bitmap_granularity(bitmap);
 274     uint64_t limit = granularity * (s->cluster_size << 3);
 275
 276     assert(QEMU_IS_ALIGNED(limit,
 277                            bdrv_dirty_bitmap_serialization_align(bitmap)));
 278     return limit;
 279 }
 280
 281 /* load_bitmap_data
 282  * @bitmap_table entries must satisfy specification constraints.
 283  * @bitmap must be cleared */
 284 static int load_bitmap_data(BlockDriverState *bs,
 285                             const uint64_t *bitmap_table,
 286                             uint32_t bitmap_table_size,
 287                             BdrvDirtyBitmap *bitmap)
 288 {
 289     int ret = 0;
 290     BDRVQcow2State *s = bs->opaque;
 291     uint64_t offset, limit;
 292     uint64_t bm_size = bdrv_dirty_bitmap_size(bitmap);
 293     uint8_t *buf = NULL;
 294     uint64_t i, tab_size =
 295             size_to_clusters(s,
 296                 bdrv_dirty_bitmap_serialization_size(bitmap, 0, bm_size));
 297
 298     if (tab_size != bitmap_table_size || tab_size > BME_MAX_TABLE_SIZE) {
 299         return -EINVAL;
 300     }
 301
 302     buf = g_malloc(s->cluster_size);
 303     limit = bytes_covered_by_bitmap_cluster(s, bitmap);
 304     for (i = 0, offset = 0; i < tab_size; ++i, offset += limit) {
 305         uint64_t count = MIN(bm_size - offset, limit);
 306         uint64_t entry = bitmap_table[i];
 307         uint64_t data_offset = entry & BME_TABLE_ENTRY_OFFSET_MASK;
 308
 309         assert(check_table_entry(entry, s->cluster_size) == 0);
 310
 311         if (data_offset == 0) {
 312             if (entry & BME_TABLE_ENTRY_FLAG_ALL_ONES) {
 313                 bdrv_dirty_bitmap_deserialize_ones(bitmap, offset, count,
 314                                                    false);
 315             } else {
 316                 /* No need to deserialize zeros because the dirty bitmap is
 317                  * already cleared */
 318             }
 319         } else {
 320             ret = bdrv_pread(bs->file, data_offset, buf, s->cluster_size);
 321             if (ret < 0) {
 322                 goto finish;
 323             }
 324             bdrv_dirty_bitmap_deserialize_part(bitmap, buf, offset, count,
 325                                                false);
 326         }
 327     }
 328     ret = 0;
 329
 330     bdrv_dirty_bitmap_deserialize_finish(bitmap);
 331
 332 finish:
 333     g_free(buf);
 334
 335     return ret;
 336 }
 337
 338 static BdrvDirtyBitmap *load_bitmap(BlockDriverState *bs,
 339                                     Qcow2Bitmap *bm, Error **errp)
 340 {
 341     int ret;
 342     uint64_t *bitmap_table = NULL;
 343     uint32_t granularity;
 344     BdrvDirtyBitmap *bitmap = NULL;
 345
 346     if (bm->flags & BME_FLAG_IN_USE) {
 347         error_setg(errp, "Bitmap '%s' is in use", bm->name);
 348         goto fail;
 349     }
 350
 351     ret = bitmap_table_load(bs, &bm->table, &bitmap_table);
 352     if (ret < 0) {
 353         error_setg_errno(errp, -ret,
 354                          "Could not read bitmap_table table from image for "
 355                          "bitmap '%s'", bm->name);
 356         goto fail;
 357     }
 358
 359     granularity = 1U << bm->granularity_bits;
 360     bitmap = bdrv_create_dirty_bitmap(bs, granularity, bm->name, errp);
 361     if (bitmap == NULL) {
 362         goto fail;
 363     }
 364
 365     ret = load_bitmap_data(bs, bitmap_table, bm->table.size, bitmap);
 366     if (ret < 0) {
 367         error_setg_errno(errp, -ret, "Could not read bitmap '%s' from image",
 368                          bm->name);
 369         goto fail;
 370     }
 371
 372     g_free(bitmap_table);
 373     return bitmap;
 374
 375 fail:
 376     g_free(bitmap_table);
 377     if (bitmap != NULL) {
 378         bdrv_release_dirty_bitmap(bs, bitmap);
 379     }
 380
 381     return NULL;
 382 }
 383
 384 /*
 385  * Bitmap List
 386  */
 387
 388 /*
 389  * Bitmap List private functions
 390  * Only Bitmap List knows about bitmap directory structure in Qcow2.
 391  */
 392
 393 static inline void bitmap_dir_entry_to_cpu(Qcow2BitmapDirEntry *entry)
 394 {
 395     entry->bitmap_table_offset = be64_to_cpu(entry->bitmap_table_offset);
 396     entry->bitmap_table_size = be32_to_cpu(entry->bitmap_table_size);
 397     entry->flags = be32_to_cpu(entry->flags);
 398     entry->name_size = be16_to_cpu(entry->name_size);
 399     entry->extra_data_size = be32_to_cpu(entry->extra_data_size);
 400 }
 401
 402 static inline void bitmap_dir_entry_to_be(Qcow2BitmapDirEntry *entry)
 403 {
 404     entry->bitmap_table_offset = cpu_to_be64(entry->bitmap_table_offset);
 405     entry->bitmap_table_size = cpu_to_be32(entry->bitmap_table_size);
 406     entry->flags = cpu_to_be32(entry->flags);
 407     entry->name_size = cpu_to_be16(entry->name_size);
 408     entry->extra_data_size = cpu_to_be32(entry->extra_data_size);
 409 }
 410
 411 static inline int calc_dir_entry_size(size_t name_size, size_t extra_data_size)
 412 {
 413     int size = sizeof(Qcow2BitmapDirEntry) + name_size + extra_data_size;
 414     return ROUND_UP(size, 8);
 415 }
 416
 417 static inline int dir_entry_size(Qcow2BitmapDirEntry *entry)
 418 {
 419     return calc_dir_entry_size(entry->name_size, entry->extra_data_size);
 420 }
 421
 422 static inline const char *dir_entry_name_field(Qcow2BitmapDirEntry *entry)
 423 {
 424     return (const char *)(entry + 1) + entry->extra_data_size;
 425 }
 426
 427 static inline char *dir_entry_copy_name(Qcow2BitmapDirEntry *entry)
 428 {
 429     const char *name_field = dir_entry_name_field(entry);
 430     return g_strndup(name_field, entry->name_size);
 431 }
 432
 433 static inline Qcow2BitmapDirEntry *next_dir_entry(Qcow2BitmapDirEntry *entry)
 434 {
 435     return (Qcow2BitmapDirEntry *)((uint8_t *)entry + dir_entry_size(entry));
 436 }
 437
 438 static int check_dir_entry(BlockDriverState *bs, Qcow2BitmapDirEntry *entry)
 439 {
 440     BDRVQcow2State *s = bs->opaque;
 441     uint64_t phys_bitmap_bytes;
 442     int64_t len;
 443
 444     bool fail = (entry->bitmap_table_size == 0) ||
 445                 (entry->bitmap_table_offset == 0) ||
 446                 (entry->bitmap_table_offset % s->cluster_size) ||
 447                 (entry->bitmap_table_size > BME_MAX_TABLE_SIZE) ||
 448                 (entry->granularity_bits > BME_MAX_GRANULARITY_BITS) ||
 449                 (entry->granularity_bits < BME_MIN_GRANULARITY_BITS) ||
 450                 (entry->flags & BME_RESERVED_FLAGS) ||
 451                 (entry->name_size > BME_MAX_NAME_SIZE) ||
 452                 (entry->type != BT_DIRTY_TRACKING_BITMAP);
 453
 454     if (fail) {
 455         return -EINVAL;
 456     }
 457
 458     phys_bitmap_bytes = (uint64_t)entry->bitmap_table_size * s->cluster_size;
 459     len = bdrv_getlength(bs);
 460
 461     if (len < 0) {
 462         return len;
 463     }
 464
 465     fail = (phys_bitmap_bytes > BME_MAX_PHYS_SIZE) ||
 466            (len > ((phys_bitmap_bytes * 8) << entry->granularity_bits));
 467
 468     return fail ? -EINVAL : 0;
 469 }
 470
 471 static inline void bitmap_directory_to_be(uint8_t *dir, size_t size)
 472 {
 473     uint8_t *end = dir + size;
 474     while (dir < end) {
 475         Qcow2BitmapDirEntry *e = (Qcow2BitmapDirEntry *)dir;
 476         dir += dir_entry_size(e);
 477
 478         bitmap_dir_entry_to_be(e);
 479     }
 480 }
 481
 482 /*
 483  * Bitmap List public functions
 484  */
 485
 486 static void bitmap_free(Qcow2Bitmap *bm)
 487 {
 488     if (bm == NULL) {
 489         return;
 490     }
 491
 492     g_free(bm->name);
 493     g_free(bm);
 494 }
 495
 496 static void bitmap_list_free(Qcow2BitmapList *bm_list)
 497 {
 498     Qcow2Bitmap *bm;
 499
 500     if (bm_list == NULL) {
 501         return;
 502     }
 503
 504     while ((bm = QSIMPLEQ_FIRST(bm_list)) != NULL) {
 505         QSIMPLEQ_REMOVE_HEAD(bm_list, entry);
 506         bitmap_free(bm);
 507     }
 508
 509     g_free(bm_list);
 510 }
 511
 512 static Qcow2BitmapList *bitmap_list_new(void)
 513 {
 514     Qcow2BitmapList *bm_list = g_new(Qcow2BitmapList, 1);
 515     QSIMPLEQ_INIT(bm_list);
 516
 517     return bm_list;
 518 }
 519
 520 static uint32_t bitmap_list_count(Qcow2BitmapList *bm_list)
 521 {
 522     Qcow2Bitmap *bm;
 523     uint32_t nb_bitmaps = 0;
 524
 525     QSIMPLEQ_FOREACH(bm, bm_list, entry) {
 526         nb_bitmaps++;
 527     }
 528
 529     return nb_bitmaps;
 530 }
 531
 532 /* bitmap_list_load
 533  * Get bitmap list from qcow2 image. Actually reads bitmap directory,
 534  * checks it and convert to bitmap list.
 535  */
 536 static Qcow2BitmapList *bitmap_list_load(BlockDriverState *bs, uint64_t offset,
 537                                          uint64_t size, Error **errp)
 538 {
 539     int ret;
 540     BDRVQcow2State *s = bs->opaque;
 541     uint8_t *dir, *dir_end;
 542     Qcow2BitmapDirEntry *e;
 543     uint32_t nb_dir_entries = 0;
 544     Qcow2BitmapList *bm_list = NULL;
 545
 546     if (size == 0) {
 547         error_setg(errp, "Requested bitmap directory size is zero");
 548         return NULL;
 549     }
 550
 551     if (size > QCOW2_MAX_BITMAP_DIRECTORY_SIZE) {
 552         error_setg(errp, "Requested bitmap directory size is too big");
 553         return NULL;
 554     }
 555
 556     dir = g_try_malloc(size);
 557     if (dir == NULL) {
 558         error_setg(errp, "Failed to allocate space for bitmap directory");
 559         return NULL;
 560     }
 561     dir_end = dir + size;
 562
 563     ret = bdrv_pread(bs->file, offset, dir, size);
 564     if (ret < 0) {
 565         error_setg_errno(errp, -ret, "Failed to read bitmap directory");
 566         goto fail;
 567     }
 568
 569     bm_list = bitmap_list_new();
 570     for (e = (Qcow2BitmapDirEntry *)dir;
 571          e < (Qcow2BitmapDirEntry *)dir_end;
 572          e = next_dir_entry(e))
 573     {
 574         Qcow2Bitmap *bm;
 575
 576         if ((uint8_t *)(e + 1) > dir_end) {
 577             goto broken_dir;
 578         }
 579
 580         if (++nb_dir_entries > s->nb_bitmaps) {
 581             error_setg(errp, "More bitmaps found than specified in header"
 582                        " extension");
 583             goto fail;
 584         }
 585         bitmap_dir_entry_to_cpu(e);
 586
 587         if ((uint8_t *)next_dir_entry(e) > dir_end) {
 588             goto broken_dir;
 589         }
 590
 591         if (e->extra_data_size != 0) {
 592             error_setg(errp, "Bitmap extra data is not supported");
 593             goto fail;
 594         }
 595
 596         ret = check_dir_entry(bs, e);
 597         if (ret < 0) {
 598             error_setg(errp, "Bitmap '%.*s' doesn't satisfy the constraints",
 599                        e->name_size, dir_entry_name_field(e));
 600             goto fail;
 601         }
 602
 603         bm = g_new0(Qcow2Bitmap, 1);
 604         bm->table.offset = e->bitmap_table_offset;
 605         bm->table.size = e->bitmap_table_size;
 606         bm->flags = e->flags;
 607         bm->granularity_bits = e->granularity_bits;
 608         bm->name = dir_entry_copy_name(e);
 609         QSIMPLEQ_INSERT_TAIL(bm_list, bm, entry);
 610     }
 611
 612     if (nb_dir_entries != s->nb_bitmaps) {
 613         error_setg(errp, "Less bitmaps found than specified in header"
 614                          " extension");
 615         goto fail;
 616     }
 617
 618     if ((uint8_t *)e != dir_end) {
 619         goto broken_dir;
 620     }
 621
 622     g_free(dir);
 623     return bm_list;
 624
 625 broken_dir:
 626     ret = -EINVAL;
 627     error_setg(errp, "Broken bitmap directory");
 628
 629 fail:
 630     g_free(dir);
 631     bitmap_list_free(bm_list);
 632
 633     return NULL;
 634 }
 635
 636 int qcow2_check_bitmaps_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
 637                                   void **refcount_table,
 638                                   int64_t *refcount_table_size)
 639 {
 640     int ret;
 641     BDRVQcow2State *s = bs->opaque;
 642     Qcow2BitmapList *bm_list;
 643     Qcow2Bitmap *bm;
 644
 645     if (s->nb_bitmaps == 0) {
 646         return 0;
 647     }
 648
 649     ret = qcow2_inc_refcounts_imrt(bs, res, refcount_table, refcount_table_size,
 650                                    s->bitmap_directory_offset,
 651                                    s->bitmap_directory_size);
 652     if (ret < 0) {
 653         return ret;
 654     }
 655
 656     bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
 657                                s->bitmap_directory_size, NULL);
 658     if (bm_list == NULL) {
 659         res->corruptions++;
 660         return -EINVAL;
 661     }
 662
 663     QSIMPLEQ_FOREACH(bm, bm_list, entry) {
 664         uint64_t *bitmap_table = NULL;
 665         int i;
 666
 667         ret = qcow2_inc_refcounts_imrt(bs, res,
 668                                        refcount_table, refcount_table_size,
 669                                        bm->table.offset,
 670                                        bm->table.size * sizeof(uint64_t));
 671         if (ret < 0) {
 672             goto out;
 673         }
 674
 675         ret = bitmap_table_load(bs, &bm->table, &bitmap_table);
 676         if (ret < 0) {
 677             res->corruptions++;
 678             goto out;
 679         }
 680
 681         for (i = 0; i < bm->table.size; ++i) {
 682             uint64_t entry = bitmap_table[i];
 683             uint64_t offset = entry & BME_TABLE_ENTRY_OFFSET_MASK;
 684
 685             if (check_table_entry(entry, s->cluster_size) < 0) {
 686                 res->corruptions++;
 687                 continue;
 688             }
 689
 690             if (offset == 0) {
 691                 continue;
 692             }
 693
 694             ret = qcow2_inc_refcounts_imrt(bs, res,
 695                                            refcount_table, refcount_table_size,
 696                                            offset, s->cluster_size);
 697             if (ret < 0) {
 698                 g_free(bitmap_table);
 699                 goto out;
 700             }
 701         }
 702
 703         g_free(bitmap_table);
 704     }
 705
 706 out:
 707     bitmap_list_free(bm_list);
 708
 709     return ret;
 710 }
 711
 712 /* bitmap_list_store
 713  * Store bitmap list to qcow2 image as a bitmap directory.
 714  * Everything is checked.
 715  */
 716 static int bitmap_list_store(BlockDriverState *bs, Qcow2BitmapList *bm_list,
 717                              uint64_t *offset, uint64_t *size, bool in_place)
 718 {
 719     int ret;
 720     uint8_t *dir;
 721     int64_t dir_offset = 0;
 722     uint64_t dir_size = 0;
 723     Qcow2Bitmap *bm;
 724     Qcow2BitmapDirEntry *e;
 725
 726     QSIMPLEQ_FOREACH(bm, bm_list, entry) {
 727         dir_size += calc_dir_entry_size(strlen(bm->name), 0);
 728     }
 729
 730     if (dir_size == 0 || dir_size > QCOW2_MAX_BITMAP_DIRECTORY_SIZE) {
 731         return -EINVAL;
 732     }
 733
 734     if (in_place) {
 735         if (*size != dir_size || *offset == 0) {
 736             return -EINVAL;
 737         }
 738
 739         dir_offset = *offset;
 740     }
 741
 742     dir = g_try_malloc(dir_size);
 743     if (dir == NULL) {
 744         return -ENOMEM;
 745     }
 746
 747     e = (Qcow2BitmapDirEntry *)dir;
 748     QSIMPLEQ_FOREACH(bm, bm_list, entry) {
 749         e->bitmap_table_offset = bm->table.offset;
 750         e->bitmap_table_size = bm->table.size;
 751         e->flags = bm->flags;
 752         e->type = BT_DIRTY_TRACKING_BITMAP;
 753         e->granularity_bits = bm->granularity_bits;
 754         e->name_size = strlen(bm->name);
 755         e->extra_data_size = 0;
 756         memcpy(e + 1, bm->name, e->name_size);
 757
 758         if (check_dir_entry(bs, e) < 0) {
 759             ret = -EINVAL;
 760             goto fail;
 761         }
 762
 763         e = next_dir_entry(e);
 764     }
 765
 766     bitmap_directory_to_be(dir, dir_size);
 767
 768     if (!in_place) {
 769         dir_offset = qcow2_alloc_clusters(bs, dir_size);
 770         if (dir_offset < 0) {
 771             ret = dir_offset;
 772             goto fail;
 773         }
 774     }
 775
 776     /* Actually, even in in-place case ignoring QCOW2_OL_BITMAP_DIRECTORY is not
 777      * necessary, because we drop QCOW2_AUTOCLEAR_BITMAPS when updating bitmap
 778      * directory in-place (actually, turn-off the extension), which is checked
 779      * in qcow2_check_metadata_overlap() */
 780     ret = qcow2_pre_write_overlap_check(
 781             bs, in_place ? QCOW2_OL_BITMAP_DIRECTORY : 0, dir_offset, dir_size);
 782     if (ret < 0) {
 783         goto fail;
 784     }
 785
 786     ret = bdrv_pwrite(bs->file, dir_offset, dir, dir_size);
 787     if (ret < 0) {
 788         goto fail;
 789     }
 790
 791     g_free(dir);
 792
 793     if (!in_place) {
 794         *size = dir_size;
 795         *offset = dir_offset;
 796     }
 797
 798     return 0;
 799
 800 fail:
 801     g_free(dir);
 802
 803     if (!in_place && dir_offset > 0) {
 804         qcow2_free_clusters(bs, dir_offset, dir_size, QCOW2_DISCARD_OTHER);
 805     }
 806
 807     return ret;
 808 }
 809
 810 /*
 811  * Bitmap List end
 812  */
 813
 814 static int update_ext_header_and_dir_in_place(BlockDriverState *bs,
 815                                               Qcow2BitmapList *bm_list)
 816 {
 817     BDRVQcow2State *s = bs->opaque;
 818     int ret;
 819
 820     if (!(s->autoclear_features & QCOW2_AUTOCLEAR_BITMAPS) ||
 821         bm_list == NULL || QSIMPLEQ_EMPTY(bm_list) ||
 822         bitmap_list_count(bm_list) != s->nb_bitmaps)
 823     {
 824         return -EINVAL;
 825     }
 826
 827     s->autoclear_features &= ~(uint64_t)QCOW2_AUTOCLEAR_BITMAPS;
 828     ret = update_header_sync(bs);
 829     if (ret < 0) {
 830         /* Two variants are possible here:
 831          * 1. Autoclear flag is dropped, all bitmaps will be lost.
 832          * 2. Autoclear flag is not dropped, old state is left.
 833          */
 834         return ret;
 835     }
 836
 837     /* autoclear bit is not set, so we can safely update bitmap directory */
 838
 839     ret = bitmap_list_store(bs, bm_list, &s->bitmap_directory_offset,
 840                             &s->bitmap_directory_size, true);
 841     if (ret < 0) {
 842         /* autoclear bit is cleared, so all leaked clusters would be removed on
 843          * qemu-img check */
 844         return ret;
 845     }
 846
 847     ret = update_header_sync(bs);
 848     if (ret < 0) {
 849         /* autoclear bit is cleared, so all leaked clusters would be removed on
 850          * qemu-img check */
 851         return ret;
 852     }
 853
 854     s->autoclear_features |= QCOW2_AUTOCLEAR_BITMAPS;
 855     return update_header_sync(bs);
 856     /* If final update_header_sync() fails, two variants are possible:
 857      * 1. Autoclear flag is not set, all bitmaps will be lost.
 858      * 2. Autoclear flag is set, header and directory are successfully updated.
 859      */
 860 }
 861
 862 static int update_ext_header_and_dir(BlockDriverState *bs,
 863                                      Qcow2BitmapList *bm_list)
 864 {
 865     BDRVQcow2State *s = bs->opaque;
 866     int ret;
 867     uint64_t new_offset = 0;
 868     uint64_t new_size = 0;
 869     uint32_t new_nb_bitmaps = 0;
 870     uint64_t old_offset = s->bitmap_directory_offset;
 871     uint64_t old_size = s->bitmap_directory_size;
 872     uint32_t old_nb_bitmaps = s->nb_bitmaps;
 873     uint64_t old_autocl = s->autoclear_features;
 874
 875     if (bm_list != NULL && !QSIMPLEQ_EMPTY(bm_list)) {
 876         new_nb_bitmaps = bitmap_list_count(bm_list);
 877
 878         if (new_nb_bitmaps > QCOW2_MAX_BITMAPS) {
 879             return -EINVAL;
 880         }
 881
 882         ret = bitmap_list_store(bs, bm_list, &new_offset, &new_size, false);
 883         if (ret < 0) {
 884             return ret;
 885         }
 886
 887         ret = qcow2_flush_caches(bs);
 888         if (ret < 0) {
 889             goto fail;
 890         }
 891
 892         s->autoclear_features |= QCOW2_AUTOCLEAR_BITMAPS;
 893     } else {
 894         s->autoclear_features &= ~(uint64_t)QCOW2_AUTOCLEAR_BITMAPS;
 895     }
 896
 897     s->bitmap_directory_offset = new_offset;
 898     s->bitmap_directory_size = new_size;
 899     s->nb_bitmaps = new_nb_bitmaps;
 900
 901     ret = update_header_sync(bs);
 902     if (ret < 0) {
 903         goto fail;
 904     }
 905
 906     if (old_size > 0) {
 907         qcow2_free_clusters(bs, old_offset, old_size, QCOW2_DISCARD_OTHER);
 908     }
 909
 910     return 0;
 911
 912 fail:
 913     if (new_offset > 0) {
 914         qcow2_free_clusters(bs, new_offset, new_size, QCOW2_DISCARD_OTHER);
 915     }
 916
 917     s->bitmap_directory_offset = old_offset;
 918     s->bitmap_directory_size = old_size;
 919     s->nb_bitmaps = old_nb_bitmaps;
 920     s->autoclear_features = old_autocl;
 921
 922     return ret;
 923 }
 924
 925 /* for g_slist_foreach for GSList of BdrvDirtyBitmap* elements */
 926 static void release_dirty_bitmap_helper(gpointer bitmap,
 927                                         gpointer bs)
 928 {
 929     bdrv_release_dirty_bitmap(bs, bitmap);
 930 }
 931
 932 /* for g_slist_foreach for GSList of BdrvDirtyBitmap* elements */
 933 static void set_readonly_helper(gpointer bitmap, gpointer value)
 934 {
 935     bdrv_dirty_bitmap_set_readonly(bitmap, (bool)value);
 936 }
 937
 938 /* qcow2_load_dirty_bitmaps()
 939  * Return value is a hint for caller: true means that the Qcow2 header was
 940  * updated. (false doesn't mean that the header should be updated by the
 941  * caller, it just means that updating was not needed or the image cannot be
 942  * written to).
 943  * On failure the function returns false.
 944  */
 945 bool qcow2_load_dirty_bitmaps(BlockDriverState *bs, Error **errp)
 946 {
 947     BDRVQcow2State *s = bs->opaque;
 948     Qcow2BitmapList *bm_list;
 949     Qcow2Bitmap *bm;
 950     GSList *created_dirty_bitmaps = NULL;
 951     bool header_updated = false;
 952
 953     if (s->nb_bitmaps == 0) {
 954         /* No bitmaps - nothing to do */
 955         return false;
 956     }
 957
 958     bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
 959                                s->bitmap_directory_size, errp);
 960     if (bm_list == NULL) {
 961         return false;
 962     }
 963
 964     QSIMPLEQ_FOREACH(bm, bm_list, entry) {
 965         if (!(bm->flags & BME_FLAG_IN_USE)) {
 966             BdrvDirtyBitmap *bitmap = load_bitmap(bs, bm, errp);
 967             if (bitmap == NULL) {
 968                 goto fail;
 969             }
 970
 971             if (!(bm->flags & BME_FLAG_AUTO)) {
 972                 bdrv_disable_dirty_bitmap(bitmap);
 973             }
 974             bdrv_dirty_bitmap_set_persistance(bitmap, true);
 975             bm->flags |= BME_FLAG_IN_USE;
 976             created_dirty_bitmaps =
 977                     g_slist_append(created_dirty_bitmaps, bitmap);
 978         }
 979     }
 980
 981     if (created_dirty_bitmaps != NULL) {
 982         if (can_write(bs)) {
 983             /* in_use flags must be updated */
 984             int ret = update_ext_header_and_dir_in_place(bs, bm_list);
 985             if (ret < 0) {
 986                 error_setg_errno(errp, -ret, "Can't update bitmap directory");
 987                 goto fail;
 988             }
 989             header_updated = true;
 990         } else {
 991             g_slist_foreach(created_dirty_bitmaps, set_readonly_helper,
 992                             (gpointer)true);
 993         }
 994     }
 995
 996     g_slist_free(created_dirty_bitmaps);
 997     bitmap_list_free(bm_list);
 998
 999     return header_updated;
1000
1001 fail:
1002     g_slist_foreach(created_dirty_bitmaps, release_dirty_bitmap_helper, bs);
1003     g_slist_free(created_dirty_bitmaps);
1004     bitmap_list_free(bm_list);
1005
1006     return false;
1007 }
1008
1009 int qcow2_reopen_bitmaps_rw_hint(BlockDriverState *bs, bool *header_updated,
1010                                  Error **errp)
1011 {
1012     BDRVQcow2State *s = bs->opaque;
1013     Qcow2BitmapList *bm_list;
1014     Qcow2Bitmap *bm;
1015     GSList *ro_dirty_bitmaps = NULL;
1016     int ret = 0;
1017
1018     if (header_updated != NULL) {
1019         *header_updated = false;
1020     }
1021
1022     if (s->nb_bitmaps == 0) {
1023         /* No bitmaps - nothing to do */
1024         return 0;
1025     }
1026
1027     if (!can_write(bs)) {
1028         error_setg(errp, "Can't write to the image on reopening bitmaps rw");
1029         return -EINVAL;
1030     }
1031
1032     bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
1033                                s->bitmap_directory_size, errp);
1034     if (bm_list == NULL) {
1035         return -EINVAL;
1036     }
1037
1038     QSIMPLEQ_FOREACH(bm, bm_list, entry) {
1039         if (!(bm->flags & BME_FLAG_IN_USE)) {
1040             BdrvDirtyBitmap *bitmap = bdrv_find_dirty_bitmap(bs, bm->name);
1041             if (bitmap == NULL) {
1042                 continue;
1043             }
1044
1045             if (!bdrv_dirty_bitmap_readonly(bitmap)) {
1046                 error_setg(errp, "Bitmap %s is not readonly but not marked"
1047                                  "'IN_USE' in the image. Something went wrong,"
1048                                  "all the bitmaps may be corrupted", bm->name);
1049                 ret = -EINVAL;
1050                 goto out;
1051             }
1052
1053             bm->flags |= BME_FLAG_IN_USE;
1054             ro_dirty_bitmaps = g_slist_append(ro_dirty_bitmaps, bitmap);
1055         }
1056     }
1057
1058     if (ro_dirty_bitmaps != NULL) {
1059         /* in_use flags must be updated */
1060         ret = update_ext_header_and_dir_in_place(bs, bm_list);
1061         if (ret < 0) {
1062             error_setg_errno(errp, -ret, "Can't update bitmap directory");
1063             goto out;
1064         }
1065         if (header_updated != NULL) {
1066             *header_updated = true;
1067         }
1068         g_slist_foreach(ro_dirty_bitmaps, set_readonly_helper, false);
1069     }
1070
1071 out:
1072     g_slist_free(ro_dirty_bitmaps);
1073     bitmap_list_free(bm_list);
1074
1075     return ret;
1076 }
1077
1078 int qcow2_reopen_bitmaps_rw(BlockDriverState *bs, Error **errp)
1079 {
1080     return qcow2_reopen_bitmaps_rw_hint(bs, NULL, errp);
1081 }
1082
1083 /* store_bitmap_data()
1084  * Store bitmap to image, filling bitmap table accordingly.
1085  */
1086 static uint64_t *store_bitmap_data(BlockDriverState *bs,
1087                                    BdrvDirtyBitmap *bitmap,
1088                                    uint32_t *bitmap_table_size, Error **errp)
1089 {
1090     int ret;
1091     BDRVQcow2State *s = bs->opaque;
1092     int64_t offset;
1093     uint64_t limit;
1094     uint64_t bm_size = bdrv_dirty_bitmap_size(bitmap);
1095     const char *bm_name = bdrv_dirty_bitmap_name(bitmap);
1096     uint8_t *buf = NULL;
1097     BdrvDirtyBitmapIter *dbi;
1098     uint64_t *tb;
1099     uint64_t tb_size =
1100             size_to_clusters(s,
1101                 bdrv_dirty_bitmap_serialization_size(bitmap, 0, bm_size));
1102
1103     if (tb_size > BME_MAX_TABLE_SIZE ||
1104         tb_size * s->cluster_size > BME_MAX_PHYS_SIZE)
1105     {
1106         error_setg(errp, "Bitmap '%s' is too big", bm_name);
1107         return NULL;
1108     }
1109
1110     tb = g_try_new0(uint64_t, tb_size);
1111     if (tb == NULL) {
1112         error_setg(errp, "No memory");
1113         return NULL;
1114     }
1115
1116     dbi = bdrv_dirty_iter_new(bitmap);
1117     buf = g_malloc(s->cluster_size);
1118     limit = bytes_covered_by_bitmap_cluster(s, bitmap);
1119     assert(DIV_ROUND_UP(bm_size, limit) == tb_size);
1120
1121     while ((offset = bdrv_dirty_iter_next(dbi)) >= 0) {
1122         uint64_t cluster = offset / limit;
1123         uint64_t end, write_size;
1124         int64_t off;
1125
1126         /*
1127          * We found the first dirty offset, but want to write out the
1128          * entire cluster of the bitmap that includes that offset,
1129          * including any leading zero bits.
1130          */
1131         offset = QEMU_ALIGN_DOWN(offset, limit);
1132         end = MIN(bm_size, offset + limit);
1133         write_size = bdrv_dirty_bitmap_serialization_size(bitmap, offset,
1134                                                           end - offset);
1135         assert(write_size <= s->cluster_size);
1136
1137         off = qcow2_alloc_clusters(bs, s->cluster_size);
1138         if (off < 0) {
1139             error_setg_errno(errp, -off,
1140                              "Failed to allocate clusters for bitmap '%s'",
1141                              bm_name);
1142             goto fail;
1143         }
1144         tb[cluster] = off;
1145
1146         bdrv_dirty_bitmap_serialize_part(bitmap, buf, offset, end - offset);
1147         if (write_size < s->cluster_size) {
1148             memset(buf + write_size, 0, s->cluster_size - write_size);
1149         }
1150
1151         ret = qcow2_pre_write_overlap_check(bs, 0, off, s->cluster_size);
1152         if (ret < 0) {
1153             error_setg_errno(errp, -ret, "Qcow2 overlap check failed");
1154             goto fail;
1155         }
1156
1157         ret = bdrv_pwrite(bs->file, off, buf, s->cluster_size);
1158         if (ret < 0) {
1159             error_setg_errno(errp, -ret, "Failed to write bitmap '%s' to file",
1160                              bm_name);
1161             goto fail;
1162         }
1163
1164         if (end >= bm_size) {
1165             break;
1166         }
1167
1168         bdrv_set_dirty_iter(dbi, end);
1169     }
1170
1171     *bitmap_table_size = tb_size;
1172     g_free(buf);
1173     bdrv_dirty_iter_free(dbi);
1174
1175     return tb;
1176
1177 fail:
1178     clear_bitmap_table(bs, tb, tb_size);
1179     g_free(buf);
1180     bdrv_dirty_iter_free(dbi);
1181     g_free(tb);
1182
1183     return NULL;
1184 }
1185
1186 /* store_bitmap()
1187  * Store bm->dirty_bitmap to qcow2.
1188  * Set bm->table_offset and bm->table_size accordingly.
1189  */
1190 static int store_bitmap(BlockDriverState *bs, Qcow2Bitmap *bm, Error **errp)
1191 {
1192     int ret;
1193     uint64_t *tb;
1194     int64_t tb_offset;
1195     uint32_t tb_size;
1196     BdrvDirtyBitmap *bitmap = bm->dirty_bitmap;
1197     const char *bm_name;
1198
1199     assert(bitmap != NULL);
1200
1201     bm_name = bdrv_dirty_bitmap_name(bitmap);
1202
1203     tb = store_bitmap_data(bs, bitmap, &tb_size, errp);
1204     if (tb == NULL) {
1205         return -EINVAL;
1206     }
1207
1208     assert(tb_size <= BME_MAX_TABLE_SIZE);
1209     tb_offset = qcow2_alloc_clusters(bs, tb_size * sizeof(tb[0]));
1210     if (tb_offset < 0) {
1211         error_setg_errno(errp, -tb_offset,
1212                          "Failed to allocate clusters for bitmap '%s'",
1213                          bm_name);
1214         ret = tb_offset;
1215         goto fail;
1216     }
1217
1218     ret = qcow2_pre_write_overlap_check(bs, 0, tb_offset,
1219                                         tb_size * sizeof(tb[0]));
1220     if (ret < 0) {
1221         error_setg_errno(errp, -ret, "Qcow2 overlap check failed");
1222         goto fail;
1223     }
1224
1225     bitmap_table_to_be(tb, tb_size);
1226     ret = bdrv_pwrite(bs->file, tb_offset, tb, tb_size * sizeof(tb[0]));
1227     if (ret < 0) {
1228         error_setg_errno(errp, -ret, "Failed to write bitmap '%s' to file",
1229                          bm_name);
1230         goto fail;
1231     }
1232
1233     g_free(tb);
1234
1235     bm->table.offset = tb_offset;
1236     bm->table.size = tb_size;
1237
1238     return 0;
1239
1240 fail:
1241     clear_bitmap_table(bs, tb, tb_size);
1242
1243     if (tb_offset > 0) {
1244         qcow2_free_clusters(bs, tb_offset, tb_size * sizeof(tb[0]),
1245                             QCOW2_DISCARD_OTHER);
1246     }
1247
1248     g_free(tb);
1249
1250     return ret;
1251 }
1252
1253 static Qcow2Bitmap *find_bitmap_by_name(Qcow2BitmapList *bm_list,
1254                                         const char *name)
1255 {
1256     Qcow2Bitmap *bm;
1257
1258     QSIMPLEQ_FOREACH(bm, bm_list, entry) {
1259         if (strcmp(name, bm->name) == 0) {
1260             return bm;
1261         }
1262     }
1263
1264     return NULL;
1265 }
1266
1267 void qcow2_remove_persistent_dirty_bitmap(BlockDriverState *bs,
1268                                           const char *name,
1269                                           Error **errp)
1270 {
1271     int ret;
1272     BDRVQcow2State *s = bs->opaque;
1273     Qcow2Bitmap *bm;
1274     Qcow2BitmapList *bm_list;
1275
1276     if (s->nb_bitmaps == 0) {
1277         /* Absence of the bitmap is not an error: see explanation above
1278          * bdrv_remove_persistent_dirty_bitmap() definition. */
1279         return;
1280     }
1281
1282     bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
1283                                s->bitmap_directory_size, errp);
1284     if (bm_list == NULL) {
1285         return;
1286     }
1287
1288     bm = find_bitmap_by_name(bm_list, name);
1289     if (bm == NULL) {
1290         goto fail;
1291     }
1292
1293     QSIMPLEQ_REMOVE(bm_list, bm, Qcow2Bitmap, entry);
1294
1295     ret = update_ext_header_and_dir(bs, bm_list);
1296     if (ret < 0) {
1297         error_setg_errno(errp, -ret, "Failed to update bitmap extension");
1298         goto fail;
1299     }
1300
1301     free_bitmap_clusters(bs, &bm->table);
1302
1303 fail:
1304     bitmap_free(bm);
1305     bitmap_list_free(bm_list);
1306 }
1307
1308 void qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs, Error **errp)
1309 {
1310     BdrvDirtyBitmap *bitmap;
1311     BDRVQcow2State *s = bs->opaque;
1312     uint32_t new_nb_bitmaps = s->nb_bitmaps;
1313     uint64_t new_dir_size = s->bitmap_directory_size;
1314     int ret;
1315     Qcow2BitmapList *bm_list;
1316     Qcow2Bitmap *bm;
1317     QSIMPLEQ_HEAD(, Qcow2BitmapTable) drop_tables;
1318     Qcow2BitmapTable *tb, *tb_next;
1319
1320     if (!bdrv_has_changed_persistent_bitmaps(bs)) {
1321         /* nothing to do */
1322         return;
1323     }
1324
1325     if (!can_write(bs)) {
1326         error_setg(errp, "No write access");
1327         return;
1328     }
1329
1330     QSIMPLEQ_INIT(&drop_tables);
1331
1332     if (s->nb_bitmaps == 0) {
1333         bm_list = bitmap_list_new();
1334     } else {
1335         bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
1336                                    s->bitmap_directory_size, errp);
1337         if (bm_list == NULL) {
1338             return;
1339         }
1340     }
1341
1342     /* check constraints and names */
1343     for (bitmap = bdrv_dirty_bitmap_next(bs, NULL); bitmap != NULL;
1344          bitmap = bdrv_dirty_bitmap_next(bs, bitmap))
1345     {
1346         const char *name = bdrv_dirty_bitmap_name(bitmap);
1347         uint32_t granularity = bdrv_dirty_bitmap_granularity(bitmap);
1348         Qcow2Bitmap *bm;
1349
1350         if (!bdrv_dirty_bitmap_get_persistance(bitmap) ||
1351             bdrv_dirty_bitmap_readonly(bitmap))
1352         {
1353             continue;
1354         }
1355
1356         if (check_constraints_on_bitmap(bs, name, granularity, errp) < 0) {
1357             error_prepend(errp, "Bitmap '%s' doesn't satisfy the constraints: ",
1358                           name);
1359             goto fail;
1360         }
1361
1362         bm = find_bitmap_by_name(bm_list, name);
1363         if (bm == NULL) {
1364             if (++new_nb_bitmaps > QCOW2_MAX_BITMAPS) {
1365                 error_setg(errp, "Too many persistent bitmaps");
1366                 goto fail;
1367             }
1368
1369             new_dir_size += calc_dir_entry_size(strlen(name), 0);
1370             if (new_dir_size > QCOW2_MAX_BITMAP_DIRECTORY_SIZE) {
1371                 error_setg(errp, "Bitmap directory is too large");
1372                 goto fail;
1373             }
1374
1375             bm = g_new0(Qcow2Bitmap, 1);
1376             bm->name = g_strdup(name);
1377             QSIMPLEQ_INSERT_TAIL(bm_list, bm, entry);
1378         } else {
1379             if (!(bm->flags & BME_FLAG_IN_USE)) {
1380                 error_setg(errp, "Bitmap '%s' already exists in the image",
1381                            name);
1382                 goto fail;
1383             }
1384             tb = g_memdup(&bm->table, sizeof(bm->table));
1385             bm->table.offset = 0;
1386             bm->table.size = 0;
1387             QSIMPLEQ_INSERT_TAIL(&drop_tables, tb, entry);
1388         }
1389         bm->flags = bdrv_dirty_bitmap_enabled(bitmap) ? BME_FLAG_AUTO : 0;
1390         bm->granularity_bits = ctz32(bdrv_dirty_bitmap_granularity(bitmap));
1391         bm->dirty_bitmap = bitmap;
1392     }
1393
1394     /* allocate clusters and store bitmaps */
1395     QSIMPLEQ_FOREACH(bm, bm_list, entry) {
1396         if (bm->dirty_bitmap == NULL) {
1397             continue;
1398         }
1399
1400         ret = store_bitmap(bs, bm, errp);
1401         if (ret < 0) {
1402             goto fail;
1403         }
1404     }
1405
1406     ret = update_ext_header_and_dir(bs, bm_list);
1407     if (ret < 0) {
1408         error_setg_errno(errp, -ret, "Failed to update bitmap extension");
1409         goto fail;
1410     }
1411
1412     /* Bitmap directory was successfully updated, so, old data can be dropped.
1413      * TODO it is better to reuse these clusters */
1414     QSIMPLEQ_FOREACH_SAFE(tb, &drop_tables, entry, tb_next) {
1415         free_bitmap_clusters(bs, tb);
1416         g_free(tb);
1417     }
1418
1419     QSIMPLEQ_FOREACH(bm, bm_list, entry) {
1420         /* For safety, we remove bitmap after storing.
1421          * We may be here in two cases:
1422          * 1. bdrv_close. It's ok to drop bitmap.
1423          * 2. inactivation. It means migration without 'dirty-bitmaps'
1424          *    capability, so bitmaps are not marked with
1425          *    BdrvDirtyBitmap.migration flags. It's not bad to drop them too,
1426          *    and reload on invalidation.
1427          */
1428         if (bm->dirty_bitmap == NULL) {
1429             continue;
1430         }
1431
1432         bdrv_release_dirty_bitmap(bs, bm->dirty_bitmap);
1433     }
1434
1435     bitmap_list_free(bm_list);
1436     return;
1437
1438 fail:
1439     QSIMPLEQ_FOREACH(bm, bm_list, entry) {
1440         if (bm->dirty_bitmap == NULL || bm->table.offset == 0) {
1441             continue;
1442         }
1443
1444         free_bitmap_clusters(bs, &bm->table);
1445     }
1446
1447     QSIMPLEQ_FOREACH_SAFE(tb, &drop_tables, entry, tb_next) {
1448         g_free(tb);
1449     }
1450
1451     bitmap_list_free(bm_list);
1452 }
1453
1454 int qcow2_reopen_bitmaps_ro(BlockDriverState *bs, Error **errp)
1455 {
1456     BdrvDirtyBitmap *bitmap;
1457     Error *local_err = NULL;
1458
1459     qcow2_store_persistent_dirty_bitmaps(bs, &local_err);
1460     if (local_err != NULL) {
1461         error_propagate(errp, local_err);
1462         return -EINVAL;
1463     }
1464
1465     for (bitmap = bdrv_dirty_bitmap_next(bs, NULL); bitmap != NULL;
1466          bitmap = bdrv_dirty_bitmap_next(bs, bitmap))
1467     {
1468         if (bdrv_dirty_bitmap_get_persistance(bitmap)) {
1469             bdrv_dirty_bitmap_set_readonly(bitmap, true);
1470         }
1471     }
1472
1473     return 0;
1474 }
1475
1476 bool qcow2_can_store_new_dirty_bitmap(BlockDriverState *bs,
1477                                       const char *name,
1478                                       uint32_t granularity,
1479                                       Error **errp)
1480 {
1481     BDRVQcow2State *s = bs->opaque;
1482     bool found;
1483     Qcow2BitmapList *bm_list;
1484
1485     if (s->qcow_version < 3) {
1486         /* Without autoclear_features, we would always have to assume
1487          * that a program without persistent dirty bitmap support has
1488          * accessed this qcow2 file when opening it, and would thus
1489          * have to drop all dirty bitmaps (defeating their purpose).
1490          */
1491         error_setg(errp, "Cannot store dirty bitmaps in qcow2 v2 files");
1492         goto fail;
1493     }
1494
1495     if (check_constraints_on_bitmap(bs, name, granularity, errp) != 0) {
1496         goto fail;
1497     }
1498
1499     if (s->nb_bitmaps == 0) {
1500         return true;
1501     }
1502
1503     if (s->nb_bitmaps >= QCOW2_MAX_BITMAPS) {
1504         error_setg(errp,
1505                    "Maximum number of persistent bitmaps is already reached");
1506         goto fail;
1507     }
1508
1509     if (s->bitmap_directory_size + calc_dir_entry_size(strlen(name), 0) >
1510         QCOW2_MAX_BITMAP_DIRECTORY_SIZE)
1511     {
1512         error_setg(errp, "Not enough space in the bitmap directory");
1513         goto fail;
1514     }
1515
1516     bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
1517                                s->bitmap_directory_size, errp);
1518     if (bm_list == NULL) {
1519         goto fail;
1520     }
1521
1522     found = find_bitmap_by_name(bm_list, name);
1523     bitmap_list_free(bm_list);
1524     if (found) {
1525         error_setg(errp, "Bitmap with the same name is already stored");
1526         goto fail;
1527     }
1528
1529     return true;
1530
1531 fail:
1532     error_prepend(errp, "Can't make bitmap '%s' persistent in '%s': ",
1533                   name, bdrv_get_device_or_node_name(bs));
1534     return false;
1535 }