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 "qcow2.h"
  33
  34 /* NOTICE: BME here means Bitmaps Extension and used as a namespace for
  35  * _internal_ constants. Please do not use this _internal_ abbreviation for
  36  * other needs and/or outside of this file. */
  37
  38 /* Bitmap directory entry constraints */
  39 #define BME_MAX_TABLE_SIZE 0x8000000
  40 #define BME_MAX_PHYS_SIZE 0x20000000 /* restrict BdrvDirtyBitmap size in RAM */
  41 #define BME_MAX_GRANULARITY_BITS 31
  42 #define BME_MIN_GRANULARITY_BITS 9
  43 #define BME_MAX_NAME_SIZE 1023
  44
  45 #if BME_MAX_TABLE_SIZE * 8ULL > INT_MAX
  46 #error In the code bitmap table physical size assumed to fit into int
  47 #endif
  48
  49 /* Bitmap directory entry flags */
  50 #define BME_RESERVED_FLAGS 0xfffffffcU
  51 #define BME_FLAG_IN_USE (1U << 0)
  52 #define BME_FLAG_AUTO   (1U << 1)
  53
  54 /* bits [1, 8] U [56, 63] are reserved */
  55 #define BME_TABLE_ENTRY_RESERVED_MASK 0xff000000000001feULL
  56 #define BME_TABLE_ENTRY_OFFSET_MASK 0x00fffffffffffe00ULL
  57 #define BME_TABLE_ENTRY_FLAG_ALL_ONES (1ULL << 0)
  58
  59 typedef struct QEMU_PACKED Qcow2BitmapDirEntry {
  60     /* header is 8 byte aligned */
  61     uint64_t bitmap_table_offset;
  62
  63     uint32_t bitmap_table_size;
  64     uint32_t flags;
  65
  66     uint8_t type;
  67     uint8_t granularity_bits;
  68     uint16_t name_size;
  69     uint32_t extra_data_size;
  70     /* extra data follows  */
  71     /* name follows  */
  72 } Qcow2BitmapDirEntry;
  73
  74 typedef struct Qcow2BitmapTable {
  75     uint64_t offset;
  76     uint32_t size; /* number of 64bit entries */
  77     QSIMPLEQ_ENTRY(Qcow2BitmapTable) entry;
  78 } Qcow2BitmapTable;
  79
  80 typedef struct Qcow2Bitmap {
  81     Qcow2BitmapTable table;
  82     uint32_t flags;
  83     uint8_t granularity_bits;
  84     char *name;
  85
  86     BdrvDirtyBitmap *dirty_bitmap;
  87
  88     QSIMPLEQ_ENTRY(Qcow2Bitmap) entry;
  89 } Qcow2Bitmap;
  90 typedef QSIMPLEQ_HEAD(Qcow2BitmapList, Qcow2Bitmap) Qcow2BitmapList;
  91
  92 typedef enum BitmapType {
  93     BT_DIRTY_TRACKING_BITMAP = 1
  94 } BitmapType;
  95
  96 static inline bool can_write(BlockDriverState *bs)
  97 {
  98     return !bdrv_is_read_only(bs) && !(bdrv_get_flags(bs) & BDRV_O_INACTIVE);
  99 }
 100
 101 static int update_header_sync(BlockDriverState *bs)
 102 {
 103     int ret;
 104
 105     ret = qcow2_update_header(bs);
 106     if (ret < 0) {
 107         return ret;
 108     }
 109
 110     return bdrv_flush(bs->file->bs);
 111 }
 112
 113 static inline void bitmap_table_to_be(uint64_t *bitmap_table, size_t size)
 114 {
 115     size_t i;
 116
 117     for (i = 0; i < size; ++i) {
 118         bitmap_table[i] = cpu_to_be64(bitmap_table[i]);
 119     }
 120 }
 121
 122 static int check_table_entry(uint64_t entry, int cluster_size)
 123 {
 124     uint64_t offset;
 125
 126     if (entry & BME_TABLE_ENTRY_RESERVED_MASK) {
 127         return -EINVAL;
 128     }
 129
 130     offset = entry & BME_TABLE_ENTRY_OFFSET_MASK;
 131     if (offset != 0) {
 132         /* if offset specified, bit 0 is reserved */
 133         if (entry & BME_TABLE_ENTRY_FLAG_ALL_ONES) {
 134             return -EINVAL;
 135         }
 136
 137         if (offset % cluster_size != 0) {
 138             return -EINVAL;
 139         }
 140     }
 141
 142     return 0;
 143 }
 144
 145 static int check_constraints_on_bitmap(BlockDriverState *bs,
 146                                        const char *name,
 147                                        uint32_t granularity,
 148                                        Error **errp)
 149 {
 150     BDRVQcow2State *s = bs->opaque;
 151     int granularity_bits = ctz32(granularity);
 152     int64_t len = bdrv_getlength(bs);
 153
 154     assert(granularity > 0);
 155     assert((granularity & (granularity - 1)) == 0);
 156
 157     if (len < 0) {
 158         error_setg_errno(errp, -len, "Failed to get size of '%s'",
 159                          bdrv_get_device_or_node_name(bs));
 160         return len;
 161     }
 162
 163     if (granularity_bits > BME_MAX_GRANULARITY_BITS) {
 164         error_setg(errp, "Granularity exceeds maximum (%llu bytes)",
 165                    1ULL << BME_MAX_GRANULARITY_BITS);
 166         return -EINVAL;
 167     }
 168     if (granularity_bits < BME_MIN_GRANULARITY_BITS) {
 169         error_setg(errp, "Granularity is under minimum (%llu bytes)",
 170                    1ULL << BME_MIN_GRANULARITY_BITS);
 171         return -EINVAL;
 172     }
 173
 174     if ((len > (uint64_t)BME_MAX_PHYS_SIZE << granularity_bits) ||
 175         (len > (uint64_t)BME_MAX_TABLE_SIZE * s->cluster_size <<
 176                granularity_bits))
 177     {
 178         error_setg(errp, "Too much space will be occupied by the bitmap. "
 179                    "Use larger granularity");
 180         return -EINVAL;
 181     }
 182
 183     if (strlen(name) > BME_MAX_NAME_SIZE) {
 184         error_setg(errp, "Name length exceeds maximum (%u characters)",
 185                    BME_MAX_NAME_SIZE);
 186         return -EINVAL;
 187     }
 188
 189     return 0;
 190 }
 191
 192 static void clear_bitmap_table(BlockDriverState *bs, uint64_t *bitmap_table,
 193                                uint32_t bitmap_table_size)
 194 {
 195     BDRVQcow2State *s = bs->opaque;
 196     int i;
 197
 198     for (i = 0; i < bitmap_table_size; ++i) {
 199         uint64_t addr = bitmap_table[i] & BME_TABLE_ENTRY_OFFSET_MASK;
 200         if (!addr) {
 201             continue;
 202         }
 203
 204         qcow2_free_clusters(bs, addr, s->cluster_size, QCOW2_DISCARD_ALWAYS);
 205         bitmap_table[i] = 0;
 206     }
 207 }
 208
 209 static int bitmap_table_load(BlockDriverState *bs, Qcow2BitmapTable *tb,
 210                              uint64_t **bitmap_table)
 211 {
 212     int ret;
 213     BDRVQcow2State *s = bs->opaque;
 214     uint32_t i;
 215     uint64_t *table;
 216
 217     assert(tb->size != 0);
 218     table = g_try_new(uint64_t, tb->size);
 219     if (table == NULL) {
 220         return -ENOMEM;
 221     }
 222
 223     assert(tb->size <= BME_MAX_TABLE_SIZE);
 224     ret = bdrv_pread(bs->file, tb->offset,
 225                      table, tb->size * sizeof(uint64_t));
 226     if (ret < 0) {
 227         goto fail;
 228     }
 229
 230     for (i = 0; i < tb->size; ++i) {
 231         table[i] = be64_to_cpu(table[i]);
 232         ret = check_table_entry(table[i], s->cluster_size);
 233         if (ret < 0) {
 234             goto fail;
 235         }
 236     }
 237
 238     *bitmap_table = table;
 239     return 0;
 240
 241 fail:
 242     g_free(table);
 243
 244     return ret;
 245 }
 246
 247 static int free_bitmap_clusters(BlockDriverState *bs, Qcow2BitmapTable *tb)
 248 {
 249     int ret;
 250     uint64_t *bitmap_table;
 251
 252     ret = bitmap_table_load(bs, tb, &bitmap_table);
 253     if (ret < 0) {
 254         return ret;
 255     }
 256
 257     clear_bitmap_table(bs, bitmap_table, tb->size);
 258     qcow2_free_clusters(bs, tb->offset, tb->size * sizeof(uint64_t),
 259                         QCOW2_DISCARD_OTHER);
 260     g_free(bitmap_table);
 261
 262     tb->offset = 0;
 263     tb->size = 0;
 264
 265     return 0;
 266 }
 267
 268 /* Return the disk size covered by a single qcow2 cluster of bitmap data. */
 269 static uint64_t bytes_covered_by_bitmap_cluster(const BDRVQcow2State *s,
 270                                                 const BdrvDirtyBitmap *bitmap)
 271 {
 272     uint64_t granularity = bdrv_dirty_bitmap_granularity(bitmap);
 273     uint64_t limit = granularity * (s->cluster_size << 3);
 274
 275     assert(QEMU_IS_ALIGNED(limit,
 276                            bdrv_dirty_bitmap_serialization_align(bitmap)));
 277     return limit;
 278 }
 279
 280 /* load_bitmap_data
 281  * @bitmap_table entries must satisfy specification constraints.
 282  * @bitmap must be cleared */
 283 static int load_bitmap_data(BlockDriverState *bs,
 284                             const uint64_t *bitmap_table,
 285                             uint32_t bitmap_table_size,
 286                             BdrvDirtyBitmap *bitmap)
 287 {
 288     int ret = 0;
 289     BDRVQcow2State *s = bs->opaque;
 290     uint64_t offset, limit;
 291     uint64_t bm_size = bdrv_dirty_bitmap_size(bitmap);
 292     uint8_t *buf = NULL;
 293     uint64_t i, tab_size =
 294             size_to_clusters(s,
 295                 bdrv_dirty_bitmap_serialization_size(bitmap, 0, bm_size));
 296
 297     if (tab_size != bitmap_table_size || tab_size > BME_MAX_TABLE_SIZE) {
 298         return -EINVAL;
 299     }
 300
 301     buf = g_malloc(s->cluster_size);
 302     limit = bytes_covered_by_bitmap_cluster(s, bitmap);
 303     for (i = 0, offset = 0; i < tab_size; ++i, offset += limit) {
 304         uint64_t count = MIN(bm_size - offset, limit);
 305         uint64_t entry = bitmap_table[i];
 306         uint64_t data_offset = entry & BME_TABLE_ENTRY_OFFSET_MASK;
 307
 308         assert(check_table_entry(entry, s->cluster_size) == 0);
 309
 310         if (data_offset == 0) {
 311             if (entry & BME_TABLE_ENTRY_FLAG_ALL_ONES) {
 312                 bdrv_dirty_bitmap_deserialize_ones(bitmap, offset, count,
 313                                                    false);
 314             } else {
 315                 /* No need to deserialize zeros because the dirty bitmap is
 316                  * already cleared */
 317             }
 318         } else {
 319             ret = bdrv_pread(bs->file, data_offset, buf, s->cluster_size);
 320             if (ret < 0) {
 321                 goto finish;
 322             }
 323             bdrv_dirty_bitmap_deserialize_part(bitmap, buf, offset, count,
 324                                                false);
 325         }
 326     }
 327     ret = 0;
 328
 329     bdrv_dirty_bitmap_deserialize_finish(bitmap);
 330
 331 finish:
 332     g_free(buf);
 333
 334     return ret;
 335 }
 336
 337 static BdrvDirtyBitmap *load_bitmap(BlockDriverState *bs,
 338                                     Qcow2Bitmap *bm, Error **errp)
 339 {
 340     int ret;
 341     uint64_t *bitmap_table = NULL;
 342     uint32_t granularity;
 343     BdrvDirtyBitmap *bitmap = NULL;
 344
 345     granularity = 1U << bm->granularity_bits;
 346     bitmap = bdrv_create_dirty_bitmap(bs, granularity, bm->name, errp);
 347     if (bitmap == NULL) {
 348         goto fail;
 349     }
 350
 351     if (bm->flags & BME_FLAG_IN_USE) {
 352         /* Data is unusable, skip loading it */
 353         return bitmap;
 354     }
 355
 356     ret = bitmap_table_load(bs, &bm->table, &bitmap_table);
 357     if (ret < 0) {
 358         error_setg_errno(errp, -ret,
 359                          "Could not read bitmap_table table from image for "
 360                          "bitmap '%s'", bm->name);
 361         goto fail;
 362     }
 363
 364     ret = load_bitmap_data(bs, bitmap_table, bm->table.size, bitmap);
 365     if (ret < 0) {
 366         error_setg_errno(errp, -ret, "Could not read bitmap '%s' from image",
 367                          bm->name);
 368         goto fail;
 369     }
 370
 371     g_free(bitmap_table);
 372     return bitmap;
 373
 374 fail:
 375     g_free(bitmap_table);
 376     if (bitmap != NULL) {
 377         bdrv_release_dirty_bitmap(bs, bitmap);
 378     }
 379
 380     return NULL;
 381 }
 382
 383 /*
 384  * Bitmap List
 385  */
 386
 387 /*
 388  * Bitmap List private functions
 389  * Only Bitmap List knows about bitmap directory structure in Qcow2.
 390  */
 391
 392 static inline void bitmap_dir_entry_to_cpu(Qcow2BitmapDirEntry *entry)
 393 {
 394     entry->bitmap_table_offset = be64_to_cpu(entry->bitmap_table_offset);
 395     entry->bitmap_table_size = be32_to_cpu(entry->bitmap_table_size);
 396     entry->flags = be32_to_cpu(entry->flags);
 397     entry->name_size = be16_to_cpu(entry->name_size);
 398     entry->extra_data_size = be32_to_cpu(entry->extra_data_size);
 399 }
 400
 401 static inline void bitmap_dir_entry_to_be(Qcow2BitmapDirEntry *entry)
 402 {
 403     entry->bitmap_table_offset = cpu_to_be64(entry->bitmap_table_offset);
 404     entry->bitmap_table_size = cpu_to_be32(entry->bitmap_table_size);
 405     entry->flags = cpu_to_be32(entry->flags);
 406     entry->name_size = cpu_to_be16(entry->name_size);
 407     entry->extra_data_size = cpu_to_be32(entry->extra_data_size);
 408 }
 409
 410 static inline int calc_dir_entry_size(size_t name_size, size_t extra_data_size)
 411 {
 412     int size = sizeof(Qcow2BitmapDirEntry) + name_size + extra_data_size;
 413     return ROUND_UP(size, 8);
 414 }
 415
 416 static inline int dir_entry_size(Qcow2BitmapDirEntry *entry)
 417 {
 418     return calc_dir_entry_size(entry->name_size, entry->extra_data_size);
 419 }
 420
 421 static inline const char *dir_entry_name_field(Qcow2BitmapDirEntry *entry)
 422 {
 423     return (const char *)(entry + 1) + entry->extra_data_size;
 424 }
 425
 426 static inline char *dir_entry_copy_name(Qcow2BitmapDirEntry *entry)
 427 {
 428     const char *name_field = dir_entry_name_field(entry);
 429     return g_strndup(name_field, entry->name_size);
 430 }
 431
 432 static inline Qcow2BitmapDirEntry *next_dir_entry(Qcow2BitmapDirEntry *entry)
 433 {
 434     return (Qcow2BitmapDirEntry *)((uint8_t *)entry + dir_entry_size(entry));
 435 }
 436
 437 static int check_dir_entry(BlockDriverState *bs, Qcow2BitmapDirEntry *entry)
 438 {
 439     BDRVQcow2State *s = bs->opaque;
 440     uint64_t phys_bitmap_bytes;
 441     int64_t len;
 442
 443     bool fail = (entry->bitmap_table_size == 0) ||
 444                 (entry->bitmap_table_offset == 0) ||
 445                 (entry->bitmap_table_offset % s->cluster_size) ||
 446                 (entry->bitmap_table_size > BME_MAX_TABLE_SIZE) ||
 447                 (entry->granularity_bits > BME_MAX_GRANULARITY_BITS) ||
 448                 (entry->granularity_bits < BME_MIN_GRANULARITY_BITS) ||
 449                 (entry->flags & BME_RESERVED_FLAGS) ||
 450                 (entry->name_size > BME_MAX_NAME_SIZE) ||
 451                 (entry->type != BT_DIRTY_TRACKING_BITMAP);
 452
 453     if (fail) {
 454         return -EINVAL;
 455     }
 456
 457     phys_bitmap_bytes = (uint64_t)entry->bitmap_table_size * s->cluster_size;
 458     len = bdrv_getlength(bs);
 459
 460     if (len < 0) {
 461         return len;
 462     }
 463
 464     if (phys_bitmap_bytes > BME_MAX_PHYS_SIZE) {
 465         return -EINVAL;
 466     }
 467
 468     if (!(entry->flags & BME_FLAG_IN_USE) &&
 469         (len > ((phys_bitmap_bytes * 8) << entry->granularity_bits)))
 470     {
 471         /*
 472          * We've loaded a valid bitmap (IN_USE not set) or we are going to
 473          * store a valid bitmap, but the allocated bitmap table size is not
 474          * enough to store this bitmap.
 475          *
 476          * Note, that it's OK to have an invalid bitmap with invalid size due
 477          * to a bitmap that was not correctly saved after image resize.
 478          */
 479         return -EINVAL;
 480     }
 481
 482     return 0;
 483 }
 484
 485 static inline void bitmap_directory_to_be(uint8_t *dir, size_t size)
 486 {
 487     uint8_t *end = dir + size;
 488     while (dir < end) {
 489         Qcow2BitmapDirEntry *e = (Qcow2BitmapDirEntry *)dir;
 490         dir += dir_entry_size(e);
 491
 492         bitmap_dir_entry_to_be(e);
 493     }
 494 }
 495
 496 /*
 497  * Bitmap List public functions
 498  */
 499
 500 static void bitmap_free(Qcow2Bitmap *bm)
 501 {
 502     if (bm == NULL) {
 503         return;
 504     }
 505
 506     g_free(bm->name);
 507     g_free(bm);
 508 }
 509
 510 static void bitmap_list_free(Qcow2BitmapList *bm_list)
 511 {
 512     Qcow2Bitmap *bm;
 513
 514     if (bm_list == NULL) {
 515         return;
 516     }
 517
 518     while ((bm = QSIMPLEQ_FIRST(bm_list)) != NULL) {
 519         QSIMPLEQ_REMOVE_HEAD(bm_list, entry);
 520         bitmap_free(bm);
 521     }
 522
 523     g_free(bm_list);
 524 }
 525
 526 static Qcow2BitmapList *bitmap_list_new(void)
 527 {
 528     Qcow2BitmapList *bm_list = g_new(Qcow2BitmapList, 1);
 529     QSIMPLEQ_INIT(bm_list);
 530
 531     return bm_list;
 532 }
 533
 534 static uint32_t bitmap_list_count(Qcow2BitmapList *bm_list)
 535 {
 536     Qcow2Bitmap *bm;
 537     uint32_t nb_bitmaps = 0;
 538
 539     QSIMPLEQ_FOREACH(bm, bm_list, entry) {
 540         nb_bitmaps++;
 541     }
 542
 543     return nb_bitmaps;
 544 }
 545
 546 /* bitmap_list_load
 547  * Get bitmap list from qcow2 image. Actually reads bitmap directory,
 548  * checks it and convert to bitmap list.
 549  */
 550 static Qcow2BitmapList *bitmap_list_load(BlockDriverState *bs, uint64_t offset,
 551                                          uint64_t size, Error **errp)
 552 {
 553     int ret;
 554     BDRVQcow2State *s = bs->opaque;
 555     uint8_t *dir, *dir_end;
 556     Qcow2BitmapDirEntry *e;
 557     uint32_t nb_dir_entries = 0;
 558     Qcow2BitmapList *bm_list = NULL;
 559
 560     if (size == 0) {
 561         error_setg(errp, "Requested bitmap directory size is zero");
 562         return NULL;
 563     }
 564
 565     if (size > QCOW2_MAX_BITMAP_DIRECTORY_SIZE) {
 566         error_setg(errp, "Requested bitmap directory size is too big");
 567         return NULL;
 568     }
 569
 570     dir = g_try_malloc(size);
 571     if (dir == NULL) {
 572         error_setg(errp, "Failed to allocate space for bitmap directory");
 573         return NULL;
 574     }
 575     dir_end = dir + size;
 576
 577     ret = bdrv_pread(bs->file, offset, dir, size);
 578     if (ret < 0) {
 579         error_setg_errno(errp, -ret, "Failed to read bitmap directory");
 580         goto fail;
 581     }
 582
 583     bm_list = bitmap_list_new();
 584     for (e = (Qcow2BitmapDirEntry *)dir;
 585          e < (Qcow2BitmapDirEntry *)dir_end;
 586          e = next_dir_entry(e))
 587     {
 588         Qcow2Bitmap *bm;
 589
 590         if ((uint8_t *)(e + 1) > dir_end) {
 591             goto broken_dir;
 592         }
 593
 594         if (++nb_dir_entries > s->nb_bitmaps) {
 595             error_setg(errp, "More bitmaps found than specified in header"
 596                        " extension");
 597             goto fail;
 598         }
 599         bitmap_dir_entry_to_cpu(e);
 600
 601         if ((uint8_t *)next_dir_entry(e) > dir_end) {
 602             goto broken_dir;
 603         }
 604
 605         if (e->extra_data_size != 0) {
 606             error_setg(errp, "Bitmap extra data is not supported");
 607             goto fail;
 608         }
 609
 610         ret = check_dir_entry(bs, e);
 611         if (ret < 0) {
 612             error_setg(errp, "Bitmap '%.*s' doesn't satisfy the constraints",
 613                        e->name_size, dir_entry_name_field(e));
 614             goto fail;
 615         }
 616
 617         bm = g_new0(Qcow2Bitmap, 1);
 618         bm->table.offset = e->bitmap_table_offset;
 619         bm->table.size = e->bitmap_table_size;
 620         bm->flags = e->flags;
 621         bm->granularity_bits = e->granularity_bits;
 622         bm->name = dir_entry_copy_name(e);
 623         QSIMPLEQ_INSERT_TAIL(bm_list, bm, entry);
 624     }
 625
 626     if (nb_dir_entries != s->nb_bitmaps) {
 627         error_setg(errp, "Less bitmaps found than specified in header"
 628                          " extension");
 629         goto fail;
 630     }
 631
 632     if ((uint8_t *)e != dir_end) {
 633         goto broken_dir;
 634     }
 635
 636     g_free(dir);
 637     return bm_list;
 638
 639 broken_dir:
 640     ret = -EINVAL;
 641     error_setg(errp, "Broken bitmap directory");
 642
 643 fail:
 644     g_free(dir);
 645     bitmap_list_free(bm_list);
 646
 647     return NULL;
 648 }
 649
 650 int qcow2_check_bitmaps_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
 651                                   void **refcount_table,
 652                                   int64_t *refcount_table_size)
 653 {
 654     int ret;
 655     BDRVQcow2State *s = bs->opaque;
 656     Qcow2BitmapList *bm_list;
 657     Qcow2Bitmap *bm;
 658
 659     if (s->nb_bitmaps == 0) {
 660         return 0;
 661     }
 662
 663     ret = qcow2_inc_refcounts_imrt(bs, res, refcount_table, refcount_table_size,
 664                                    s->bitmap_directory_offset,
 665                                    s->bitmap_directory_size);
 666     if (ret < 0) {
 667         return ret;
 668     }
 669
 670     bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
 671                                s->bitmap_directory_size, NULL);
 672     if (bm_list == NULL) {
 673         res->corruptions++;
 674         return -EINVAL;
 675     }
 676
 677     QSIMPLEQ_FOREACH(bm, bm_list, entry) {
 678         uint64_t *bitmap_table = NULL;
 679         int i;
 680
 681         ret = qcow2_inc_refcounts_imrt(bs, res,
 682                                        refcount_table, refcount_table_size,
 683                                        bm->table.offset,
 684                                        bm->table.size * sizeof(uint64_t));
 685         if (ret < 0) {
 686             goto out;
 687         }
 688
 689         ret = bitmap_table_load(bs, &bm->table, &bitmap_table);
 690         if (ret < 0) {
 691             res->corruptions++;
 692             goto out;
 693         }
 694
 695         for (i = 0; i < bm->table.size; ++i) {
 696             uint64_t entry = bitmap_table[i];
 697             uint64_t offset = entry & BME_TABLE_ENTRY_OFFSET_MASK;
 698
 699             if (check_table_entry(entry, s->cluster_size) < 0) {
 700                 res->corruptions++;
 701                 continue;
 702             }
 703
 704             if (offset == 0) {
 705                 continue;
 706             }
 707
 708             ret = qcow2_inc_refcounts_imrt(bs, res,
 709                                            refcount_table, refcount_table_size,
 710                                            offset, s->cluster_size);
 711             if (ret < 0) {
 712                 g_free(bitmap_table);
 713                 goto out;
 714             }
 715         }
 716
 717         g_free(bitmap_table);
 718     }
 719
 720 out:
 721     bitmap_list_free(bm_list);
 722
 723     return ret;
 724 }
 725
 726 /* bitmap_list_store
 727  * Store bitmap list to qcow2 image as a bitmap directory.
 728  * Everything is checked.
 729  */
 730 static int bitmap_list_store(BlockDriverState *bs, Qcow2BitmapList *bm_list,
 731                              uint64_t *offset, uint64_t *size, bool in_place)
 732 {
 733     int ret;
 734     uint8_t *dir;
 735     int64_t dir_offset = 0;
 736     uint64_t dir_size = 0;
 737     Qcow2Bitmap *bm;
 738     Qcow2BitmapDirEntry *e;
 739
 740     QSIMPLEQ_FOREACH(bm, bm_list, entry) {
 741         dir_size += calc_dir_entry_size(strlen(bm->name), 0);
 742     }
 743
 744     if (dir_size == 0 || dir_size > QCOW2_MAX_BITMAP_DIRECTORY_SIZE) {
 745         return -EINVAL;
 746     }
 747
 748     if (in_place) {
 749         if (*size != dir_size || *offset == 0) {
 750             return -EINVAL;
 751         }
 752
 753         dir_offset = *offset;
 754     }
 755
 756     dir = g_try_malloc0(dir_size);
 757     if (dir == NULL) {
 758         return -ENOMEM;
 759     }
 760
 761     e = (Qcow2BitmapDirEntry *)dir;
 762     QSIMPLEQ_FOREACH(bm, bm_list, entry) {
 763         e->bitmap_table_offset = bm->table.offset;
 764         e->bitmap_table_size = bm->table.size;
 765         e->flags = bm->flags;
 766         e->type = BT_DIRTY_TRACKING_BITMAP;
 767         e->granularity_bits = bm->granularity_bits;
 768         e->name_size = strlen(bm->name);
 769         e->extra_data_size = 0;
 770         memcpy(e + 1, bm->name, e->name_size);
 771
 772         if (check_dir_entry(bs, e) < 0) {
 773             ret = -EINVAL;
 774             goto fail;
 775         }
 776
 777         e = next_dir_entry(e);
 778     }
 779
 780     bitmap_directory_to_be(dir, dir_size);
 781
 782     if (!in_place) {
 783         dir_offset = qcow2_alloc_clusters(bs, dir_size);
 784         if (dir_offset < 0) {
 785             ret = dir_offset;
 786             goto fail;
 787         }
 788     }
 789
 790     /* Actually, even in in-place case ignoring QCOW2_OL_BITMAP_DIRECTORY is not
 791      * necessary, because we drop QCOW2_AUTOCLEAR_BITMAPS when updating bitmap
 792      * directory in-place (actually, turn-off the extension), which is checked
 793      * in qcow2_check_metadata_overlap() */
 794     ret = qcow2_pre_write_overlap_check(
 795             bs, in_place ? QCOW2_OL_BITMAP_DIRECTORY : 0, dir_offset, dir_size,
 796             false);
 797     if (ret < 0) {
 798         goto fail;
 799     }
 800
 801     ret = bdrv_pwrite(bs->file, dir_offset, dir, dir_size);
 802     if (ret < 0) {
 803         goto fail;
 804     }
 805
 806     g_free(dir);
 807
 808     if (!in_place) {
 809         *size = dir_size;
 810         *offset = dir_offset;
 811     }
 812
 813     return 0;
 814
 815 fail:
 816     g_free(dir);
 817
 818     if (!in_place && dir_offset > 0) {
 819         qcow2_free_clusters(bs, dir_offset, dir_size, QCOW2_DISCARD_OTHER);
 820     }
 821
 822     return ret;
 823 }
 824
 825 /*
 826  * Bitmap List end
 827  */
 828
 829 static int update_ext_header_and_dir_in_place(BlockDriverState *bs,
 830                                               Qcow2BitmapList *bm_list)
 831 {
 832     BDRVQcow2State *s = bs->opaque;
 833     int ret;
 834
 835     if (!(s->autoclear_features & QCOW2_AUTOCLEAR_BITMAPS) ||
 836         bm_list == NULL || QSIMPLEQ_EMPTY(bm_list) ||
 837         bitmap_list_count(bm_list) != s->nb_bitmaps)
 838     {
 839         return -EINVAL;
 840     }
 841
 842     s->autoclear_features &= ~(uint64_t)QCOW2_AUTOCLEAR_BITMAPS;
 843     ret = update_header_sync(bs);
 844     if (ret < 0) {
 845         /* Two variants are possible here:
 846          * 1. Autoclear flag is dropped, all bitmaps will be lost.
 847          * 2. Autoclear flag is not dropped, old state is left.
 848          */
 849         return ret;
 850     }
 851
 852     /* autoclear bit is not set, so we can safely update bitmap directory */
 853
 854     ret = bitmap_list_store(bs, bm_list, &s->bitmap_directory_offset,
 855                             &s->bitmap_directory_size, true);
 856     if (ret < 0) {
 857         /* autoclear bit is cleared, so all leaked clusters would be removed on
 858          * qemu-img check */
 859         return ret;
 860     }
 861
 862     ret = update_header_sync(bs);
 863     if (ret < 0) {
 864         /* autoclear bit is cleared, so all leaked clusters would be removed on
 865          * qemu-img check */
 866         return ret;
 867     }
 868
 869     s->autoclear_features |= QCOW2_AUTOCLEAR_BITMAPS;
 870     return update_header_sync(bs);
 871     /* If final update_header_sync() fails, two variants are possible:
 872      * 1. Autoclear flag is not set, all bitmaps will be lost.
 873      * 2. Autoclear flag is set, header and directory are successfully updated.
 874      */
 875 }
 876
 877 static int update_ext_header_and_dir(BlockDriverState *bs,
 878                                      Qcow2BitmapList *bm_list)
 879 {
 880     BDRVQcow2State *s = bs->opaque;
 881     int ret;
 882     uint64_t new_offset = 0;
 883     uint64_t new_size = 0;
 884     uint32_t new_nb_bitmaps = 0;
 885     uint64_t old_offset = s->bitmap_directory_offset;
 886     uint64_t old_size = s->bitmap_directory_size;
 887     uint32_t old_nb_bitmaps = s->nb_bitmaps;
 888     uint64_t old_autocl = s->autoclear_features;
 889
 890     if (bm_list != NULL && !QSIMPLEQ_EMPTY(bm_list)) {
 891         new_nb_bitmaps = bitmap_list_count(bm_list);
 892
 893         if (new_nb_bitmaps > QCOW2_MAX_BITMAPS) {
 894             return -EINVAL;
 895         }
 896
 897         ret = bitmap_list_store(bs, bm_list, &new_offset, &new_size, false);
 898         if (ret < 0) {
 899             return ret;
 900         }
 901
 902         ret = qcow2_flush_caches(bs);
 903         if (ret < 0) {
 904             goto fail;
 905         }
 906
 907         s->autoclear_features |= QCOW2_AUTOCLEAR_BITMAPS;
 908     } else {
 909         s->autoclear_features &= ~(uint64_t)QCOW2_AUTOCLEAR_BITMAPS;
 910     }
 911
 912     s->bitmap_directory_offset = new_offset;
 913     s->bitmap_directory_size = new_size;
 914     s->nb_bitmaps = new_nb_bitmaps;
 915
 916     ret = update_header_sync(bs);
 917     if (ret < 0) {
 918         goto fail;
 919     }
 920
 921     if (old_size > 0) {
 922         qcow2_free_clusters(bs, old_offset, old_size, QCOW2_DISCARD_OTHER);
 923     }
 924
 925     return 0;
 926
 927 fail:
 928     if (new_offset > 0) {
 929         qcow2_free_clusters(bs, new_offset, new_size, QCOW2_DISCARD_OTHER);
 930     }
 931
 932     s->bitmap_directory_offset = old_offset;
 933     s->bitmap_directory_size = old_size;
 934     s->nb_bitmaps = old_nb_bitmaps;
 935     s->autoclear_features = old_autocl;
 936
 937     return ret;
 938 }
 939
 940 /* for g_slist_foreach for GSList of BdrvDirtyBitmap* elements */
 941 static void release_dirty_bitmap_helper(gpointer bitmap,
 942                                         gpointer bs)
 943 {
 944     bdrv_release_dirty_bitmap(bs, bitmap);
 945 }
 946
 947 /* for g_slist_foreach for GSList of BdrvDirtyBitmap* elements */
 948 static void set_readonly_helper(gpointer bitmap, gpointer value)
 949 {
 950     bdrv_dirty_bitmap_set_readonly(bitmap, (bool)value);
 951 }
 952
 953 /* qcow2_load_dirty_bitmaps()
 954  * Return value is a hint for caller: true means that the Qcow2 header was
 955  * updated. (false doesn't mean that the header should be updated by the
 956  * caller, it just means that updating was not needed or the image cannot be
 957  * written to).
 958  * On failure the function returns false.
 959  */
 960 bool qcow2_load_dirty_bitmaps(BlockDriverState *bs, Error **errp)
 961 {
 962     BDRVQcow2State *s = bs->opaque;
 963     Qcow2BitmapList *bm_list;
 964     Qcow2Bitmap *bm;
 965     GSList *created_dirty_bitmaps = NULL;
 966     bool header_updated = false;
 967     bool needs_update = false;
 968
 969     if (s->nb_bitmaps == 0) {
 970         /* No bitmaps - nothing to do */
 971         return false;
 972     }
 973
 974     bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
 975                                s->bitmap_directory_size, errp);
 976     if (bm_list == NULL) {
 977         return false;
 978     }
 979
 980     QSIMPLEQ_FOREACH(bm, bm_list, entry) {
 981         BdrvDirtyBitmap *bitmap = load_bitmap(bs, bm, errp);
 982         if (bitmap == NULL) {
 983             goto fail;
 984         }
 985
 986         bdrv_dirty_bitmap_set_persistence(bitmap, true);
 987         if (bm->flags & BME_FLAG_IN_USE) {
 988             bdrv_dirty_bitmap_set_inconsistent(bitmap);
 989         } else {
 990             /* NB: updated flags only get written if can_write(bs) is true. */
 991             bm->flags |= BME_FLAG_IN_USE;
 992             needs_update = true;
 993         }
 994         if (!(bm->flags & BME_FLAG_AUTO)) {
 995             bdrv_disable_dirty_bitmap(bitmap);
 996         }
 997         created_dirty_bitmaps =
 998             g_slist_append(created_dirty_bitmaps, bitmap);
 999     }
1000
1001     if (needs_update && can_write(bs)) {
1002         /* in_use flags must be updated */
1003         int ret = update_ext_header_and_dir_in_place(bs, bm_list);
1004         if (ret < 0) {
1005             error_setg_errno(errp, -ret, "Can't update bitmap directory");
1006             goto fail;
1007         }
1008         header_updated = true;
1009     }
1010
1011     if (!can_write(bs)) {
1012         g_slist_foreach(created_dirty_bitmaps, set_readonly_helper,
1013                         (gpointer)true);
1014     }
1015
1016     g_slist_free(created_dirty_bitmaps);
1017     bitmap_list_free(bm_list);
1018
1019     return header_updated;
1020
1021 fail:
1022     g_slist_foreach(created_dirty_bitmaps, release_dirty_bitmap_helper, bs);
1023     g_slist_free(created_dirty_bitmaps);
1024     bitmap_list_free(bm_list);
1025
1026     return false;
1027 }
1028
1029
1030 static Qcow2BitmapInfoFlagsList *get_bitmap_info_flags(uint32_t flags)
1031 {
1032     Qcow2BitmapInfoFlagsList *list = NULL;
1033     Qcow2BitmapInfoFlagsList **plist = &list;
1034     int i;
1035
1036     static const struct {
1037         int bme;  /* Bitmap directory entry flags */
1038         int info; /* The flags to report to the user */
1039     } map[] = {
1040         { BME_FLAG_IN_USE, QCOW2_BITMAP_INFO_FLAGS_IN_USE },
1041         { BME_FLAG_AUTO,   QCOW2_BITMAP_INFO_FLAGS_AUTO },
1042     };
1043
1044     int map_size = ARRAY_SIZE(map);
1045
1046     for (i = 0; i < map_size; ++i) {
1047         if (flags & map[i].bme) {
1048             Qcow2BitmapInfoFlagsList *entry =
1049                 g_new0(Qcow2BitmapInfoFlagsList, 1);
1050             entry->value = map[i].info;
1051             *plist = entry;
1052             plist = &entry->next;
1053             flags &= ~map[i].bme;
1054         }
1055     }
1056     /* Check if the BME_* mapping above is complete */
1057     assert(!flags);
1058
1059     return list;
1060 }
1061
1062 /*
1063  * qcow2_get_bitmap_info_list()
1064  * Returns a list of QCOW2 bitmap details.
1065  * In case of no bitmaps, the function returns NULL and
1066  * the @errp parameter is not set.
1067  * When bitmap information can not be obtained, the function returns
1068  * NULL and the @errp parameter is set.
1069  */
1070 Qcow2BitmapInfoList *qcow2_get_bitmap_info_list(BlockDriverState *bs,
1071                                                 Error **errp)
1072 {
1073     BDRVQcow2State *s = bs->opaque;
1074     Qcow2BitmapList *bm_list;
1075     Qcow2Bitmap *bm;
1076     Qcow2BitmapInfoList *list = NULL;
1077     Qcow2BitmapInfoList **plist = &list;
1078
1079     if (s->nb_bitmaps == 0) {
1080         return NULL;
1081     }
1082
1083     bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
1084                                s->bitmap_directory_size, errp);
1085     if (bm_list == NULL) {
1086         return NULL;
1087     }
1088
1089     QSIMPLEQ_FOREACH(bm, bm_list, entry) {
1090         Qcow2BitmapInfo *info = g_new0(Qcow2BitmapInfo, 1);
1091         Qcow2BitmapInfoList *obj = g_new0(Qcow2BitmapInfoList, 1);
1092         info->granularity = 1U << bm->granularity_bits;
1093         info->name = g_strdup(bm->name);
1094         info->flags = get_bitmap_info_flags(bm->flags & ~BME_RESERVED_FLAGS);
1095         obj->value = info;
1096         *plist = obj;
1097         plist = &obj->next;
1098     }
1099
1100     bitmap_list_free(bm_list);
1101
1102     return list;
1103 }
1104
1105 int qcow2_reopen_bitmaps_rw_hint(BlockDriverState *bs, bool *header_updated,
1106                                  Error **errp)
1107 {
1108     BDRVQcow2State *s = bs->opaque;
1109     Qcow2BitmapList *bm_list;
1110     Qcow2Bitmap *bm;
1111     GSList *ro_dirty_bitmaps = NULL;
1112     int ret = 0;
1113
1114     if (header_updated != NULL) {
1115         *header_updated = false;
1116     }
1117
1118     if (s->nb_bitmaps == 0) {
1119         /* No bitmaps - nothing to do */
1120         return 0;
1121     }
1122
1123     if (!can_write(bs)) {
1124         error_setg(errp, "Can't write to the image on reopening bitmaps rw");
1125         return -EINVAL;
1126     }
1127
1128     bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
1129                                s->bitmap_directory_size, errp);
1130     if (bm_list == NULL) {
1131         return -EINVAL;
1132     }
1133
1134     QSIMPLEQ_FOREACH(bm, bm_list, entry) {
1135         BdrvDirtyBitmap *bitmap = bdrv_find_dirty_bitmap(bs, bm->name);
1136         if (bitmap == NULL) {
1137             continue;
1138         }
1139
1140         if (!bdrv_dirty_bitmap_readonly(bitmap)) {
1141             error_setg(errp, "Bitmap %s was loaded prior to rw-reopen, but was "
1142                        "not marked as readonly. This is a bug, something went "
1143                        "wrong. All of the bitmaps may be corrupted", bm->name);
1144             ret = -EINVAL;
1145             goto out;
1146         }
1147
1148         bm->flags |= BME_FLAG_IN_USE;
1149         ro_dirty_bitmaps = g_slist_append(ro_dirty_bitmaps, bitmap);
1150     }
1151
1152     if (ro_dirty_bitmaps != NULL) {
1153         /* in_use flags must be updated */
1154         ret = update_ext_header_and_dir_in_place(bs, bm_list);
1155         if (ret < 0) {
1156             error_setg_errno(errp, -ret, "Can't update bitmap directory");
1157             goto out;
1158         }
1159         if (header_updated != NULL) {
1160             *header_updated = true;
1161         }
1162         g_slist_foreach(ro_dirty_bitmaps, set_readonly_helper, false);
1163     }
1164
1165 out:
1166     g_slist_free(ro_dirty_bitmaps);
1167     bitmap_list_free(bm_list);
1168
1169     return ret;
1170 }
1171
1172 int qcow2_reopen_bitmaps_rw(BlockDriverState *bs, Error **errp)
1173 {
1174     return qcow2_reopen_bitmaps_rw_hint(bs, NULL, errp);
1175 }
1176
1177 /* Checks to see if it's safe to resize bitmaps */
1178 int qcow2_truncate_bitmaps_check(BlockDriverState *bs, Error **errp)
1179 {
1180     BDRVQcow2State *s = bs->opaque;
1181     Qcow2BitmapList *bm_list;
1182     Qcow2Bitmap *bm;
1183     int ret = 0;
1184
1185     if (s->nb_bitmaps == 0) {
1186         return 0;
1187     }
1188
1189     bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
1190                                s->bitmap_directory_size, errp);
1191     if (bm_list == NULL) {
1192         return -EINVAL;
1193     }
1194
1195     QSIMPLEQ_FOREACH(bm, bm_list, entry) {
1196         BdrvDirtyBitmap *bitmap = bdrv_find_dirty_bitmap(bs, bm->name);
1197         if (bitmap == NULL) {
1198             /*
1199              * We rely on all bitmaps being in-memory to be able to resize them,
1200              * Otherwise, we'd need to resize them on disk explicitly
1201              */
1202             error_setg(errp, "Cannot resize qcow2 with persistent bitmaps that "
1203                        "were not loaded into memory");
1204             ret = -ENOTSUP;
1205             goto out;
1206         }
1207
1208         /*
1209          * The checks against readonly and busy are redundant, but certainly
1210          * do no harm. checks against inconsistent are crucial:
1211          */
1212         if (bdrv_dirty_bitmap_check(bitmap, BDRV_BITMAP_DEFAULT, errp)) {
1213             ret = -ENOTSUP;
1214             goto out;
1215         }
1216     }
1217
1218 out:
1219     bitmap_list_free(bm_list);
1220     return ret;
1221 }
1222
1223 /* store_bitmap_data()
1224  * Store bitmap to image, filling bitmap table accordingly.
1225  */
1226 static uint64_t *store_bitmap_data(BlockDriverState *bs,
1227                                    BdrvDirtyBitmap *bitmap,
1228                                    uint32_t *bitmap_table_size, Error **errp)
1229 {
1230     int ret;
1231     BDRVQcow2State *s = bs->opaque;
1232     int64_t offset;
1233     uint64_t limit;
1234     uint64_t bm_size = bdrv_dirty_bitmap_size(bitmap);
1235     const char *bm_name = bdrv_dirty_bitmap_name(bitmap);
1236     uint8_t *buf = NULL;
1237     BdrvDirtyBitmapIter *dbi;
1238     uint64_t *tb;
1239     uint64_t tb_size =
1240             size_to_clusters(s,
1241                 bdrv_dirty_bitmap_serialization_size(bitmap, 0, bm_size));
1242
1243     if (tb_size > BME_MAX_TABLE_SIZE ||
1244         tb_size * s->cluster_size > BME_MAX_PHYS_SIZE)
1245     {
1246         error_setg(errp, "Bitmap '%s' is too big", bm_name);
1247         return NULL;
1248     }
1249
1250     tb = g_try_new0(uint64_t, tb_size);
1251     if (tb == NULL) {
1252         error_setg(errp, "No memory");
1253         return NULL;
1254     }
1255
1256     dbi = bdrv_dirty_iter_new(bitmap);
1257     buf = g_malloc(s->cluster_size);
1258     limit = bytes_covered_by_bitmap_cluster(s, bitmap);
1259     assert(DIV_ROUND_UP(bm_size, limit) == tb_size);
1260
1261     while ((offset = bdrv_dirty_iter_next(dbi)) >= 0) {
1262         uint64_t cluster = offset / limit;
1263         uint64_t end, write_size;
1264         int64_t off;
1265
1266         /*
1267          * We found the first dirty offset, but want to write out the
1268          * entire cluster of the bitmap that includes that offset,
1269          * including any leading zero bits.
1270          */
1271         offset = QEMU_ALIGN_DOWN(offset, limit);
1272         end = MIN(bm_size, offset + limit);
1273         write_size = bdrv_dirty_bitmap_serialization_size(bitmap, offset,
1274                                                           end - offset);
1275         assert(write_size <= s->cluster_size);
1276
1277         off = qcow2_alloc_clusters(bs, s->cluster_size);
1278         if (off < 0) {
1279             error_setg_errno(errp, -off,
1280                              "Failed to allocate clusters for bitmap '%s'",
1281                              bm_name);
1282             goto fail;
1283         }
1284         tb[cluster] = off;
1285
1286         bdrv_dirty_bitmap_serialize_part(bitmap, buf, offset, end - offset);
1287         if (write_size < s->cluster_size) {
1288             memset(buf + write_size, 0, s->cluster_size - write_size);
1289         }
1290
1291         ret = qcow2_pre_write_overlap_check(bs, 0, off, s->cluster_size, false);
1292         if (ret < 0) {
1293             error_setg_errno(errp, -ret, "Qcow2 overlap check failed");
1294             goto fail;
1295         }
1296
1297         ret = bdrv_pwrite(bs->file, off, buf, s->cluster_size);
1298         if (ret < 0) {
1299             error_setg_errno(errp, -ret, "Failed to write bitmap '%s' to file",
1300                              bm_name);
1301             goto fail;
1302         }
1303
1304         if (end >= bm_size) {
1305             break;
1306         }
1307
1308         bdrv_set_dirty_iter(dbi, end);
1309     }
1310
1311     *bitmap_table_size = tb_size;
1312     g_free(buf);
1313     bdrv_dirty_iter_free(dbi);
1314
1315     return tb;
1316
1317 fail:
1318     clear_bitmap_table(bs, tb, tb_size);
1319     g_free(buf);
1320     bdrv_dirty_iter_free(dbi);
1321     g_free(tb);
1322
1323     return NULL;
1324 }
1325
1326 /* store_bitmap()
1327  * Store bm->dirty_bitmap to qcow2.
1328  * Set bm->table_offset and bm->table_size accordingly.
1329  */
1330 static int store_bitmap(BlockDriverState *bs, Qcow2Bitmap *bm, Error **errp)
1331 {
1332     int ret;
1333     uint64_t *tb;
1334     int64_t tb_offset;
1335     uint32_t tb_size;
1336     BdrvDirtyBitmap *bitmap = bm->dirty_bitmap;
1337     const char *bm_name;
1338
1339     assert(bitmap != NULL);
1340
1341     bm_name = bdrv_dirty_bitmap_name(bitmap);
1342
1343     tb = store_bitmap_data(bs, bitmap, &tb_size, errp);
1344     if (tb == NULL) {
1345         return -EINVAL;
1346     }
1347
1348     assert(tb_size <= BME_MAX_TABLE_SIZE);
1349     tb_offset = qcow2_alloc_clusters(bs, tb_size * sizeof(tb[0]));
1350     if (tb_offset < 0) {
1351         error_setg_errno(errp, -tb_offset,
1352                          "Failed to allocate clusters for bitmap '%s'",
1353                          bm_name);
1354         ret = tb_offset;
1355         goto fail;
1356     }
1357
1358     ret = qcow2_pre_write_overlap_check(bs, 0, tb_offset,
1359                                         tb_size * sizeof(tb[0]), false);
1360     if (ret < 0) {
1361         error_setg_errno(errp, -ret, "Qcow2 overlap check failed");
1362         goto fail;
1363     }
1364
1365     bitmap_table_to_be(tb, tb_size);
1366     ret = bdrv_pwrite(bs->file, tb_offset, tb, tb_size * sizeof(tb[0]));
1367     if (ret < 0) {
1368         error_setg_errno(errp, -ret, "Failed to write bitmap '%s' to file",
1369                          bm_name);
1370         goto fail;
1371     }
1372
1373     g_free(tb);
1374
1375     bm->table.offset = tb_offset;
1376     bm->table.size = tb_size;
1377
1378     return 0;
1379
1380 fail:
1381     clear_bitmap_table(bs, tb, tb_size);
1382
1383     if (tb_offset > 0) {
1384         qcow2_free_clusters(bs, tb_offset, tb_size * sizeof(tb[0]),
1385                             QCOW2_DISCARD_OTHER);
1386     }
1387
1388     g_free(tb);
1389
1390     return ret;
1391 }
1392
1393 static Qcow2Bitmap *find_bitmap_by_name(Qcow2BitmapList *bm_list,
1394                                         const char *name)
1395 {
1396     Qcow2Bitmap *bm;
1397
1398     QSIMPLEQ_FOREACH(bm, bm_list, entry) {
1399         if (strcmp(name, bm->name) == 0) {
1400             return bm;
1401         }
1402     }
1403
1404     return NULL;
1405 }
1406
1407 void qcow2_remove_persistent_dirty_bitmap(BlockDriverState *bs,
1408                                           const char *name,
1409                                           Error **errp)
1410 {
1411     int ret;
1412     BDRVQcow2State *s = bs->opaque;
1413     Qcow2Bitmap *bm;
1414     Qcow2BitmapList *bm_list;
1415
1416     if (s->nb_bitmaps == 0) {
1417         /* Absence of the bitmap is not an error: see explanation above
1418          * bdrv_remove_persistent_dirty_bitmap() definition. */
1419         return;
1420     }
1421
1422     bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
1423                                s->bitmap_directory_size, errp);
1424     if (bm_list == NULL) {
1425         return;
1426     }
1427
1428     bm = find_bitmap_by_name(bm_list, name);
1429     if (bm == NULL) {
1430         goto fail;
1431     }
1432
1433     QSIMPLEQ_REMOVE(bm_list, bm, Qcow2Bitmap, entry);
1434
1435     ret = update_ext_header_and_dir(bs, bm_list);
1436     if (ret < 0) {
1437         error_setg_errno(errp, -ret, "Failed to update bitmap extension");
1438         goto fail;
1439     }
1440
1441     free_bitmap_clusters(bs, &bm->table);
1442
1443 fail:
1444     bitmap_free(bm);
1445     bitmap_list_free(bm_list);
1446 }
1447
1448 void qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs, Error **errp)
1449 {
1450     BdrvDirtyBitmap *bitmap;
1451     BDRVQcow2State *s = bs->opaque;
1452     uint32_t new_nb_bitmaps = s->nb_bitmaps;
1453     uint64_t new_dir_size = s->bitmap_directory_size;
1454     int ret;
1455     Qcow2BitmapList *bm_list;
1456     Qcow2Bitmap *bm;
1457     QSIMPLEQ_HEAD(, Qcow2BitmapTable) drop_tables;
1458     Qcow2BitmapTable *tb, *tb_next;
1459
1460     if (!bdrv_has_changed_persistent_bitmaps(bs)) {
1461         /* nothing to do */
1462         return;
1463     }
1464
1465     if (!can_write(bs)) {
1466         error_setg(errp, "No write access");
1467         return;
1468     }
1469
1470     QSIMPLEQ_INIT(&drop_tables);
1471
1472     if (s->nb_bitmaps == 0) {
1473         bm_list = bitmap_list_new();
1474     } else {
1475         bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
1476                                    s->bitmap_directory_size, errp);
1477         if (bm_list == NULL) {
1478             return;
1479         }
1480     }
1481
1482     /* check constraints and names */
1483     for (bitmap = bdrv_dirty_bitmap_next(bs, NULL); bitmap != NULL;
1484          bitmap = bdrv_dirty_bitmap_next(bs, bitmap))
1485     {
1486         const char *name = bdrv_dirty_bitmap_name(bitmap);
1487         uint32_t granularity = bdrv_dirty_bitmap_granularity(bitmap);
1488         Qcow2Bitmap *bm;
1489
1490         if (!bdrv_dirty_bitmap_get_persistence(bitmap) ||
1491             bdrv_dirty_bitmap_readonly(bitmap) ||
1492             bdrv_dirty_bitmap_inconsistent(bitmap)) {
1493             continue;
1494         }
1495
1496         if (check_constraints_on_bitmap(bs, name, granularity, errp) < 0) {
1497             error_prepend(errp, "Bitmap '%s' doesn't satisfy the constraints: ",
1498                           name);
1499             goto fail;
1500         }
1501
1502         bm = find_bitmap_by_name(bm_list, name);
1503         if (bm == NULL) {
1504             if (++new_nb_bitmaps > QCOW2_MAX_BITMAPS) {
1505                 error_setg(errp, "Too many persistent bitmaps");
1506                 goto fail;
1507             }
1508
1509             new_dir_size += calc_dir_entry_size(strlen(name), 0);
1510             if (new_dir_size > QCOW2_MAX_BITMAP_DIRECTORY_SIZE) {
1511                 error_setg(errp, "Bitmap directory is too large");
1512                 goto fail;
1513             }
1514
1515             bm = g_new0(Qcow2Bitmap, 1);
1516             bm->name = g_strdup(name);
1517             QSIMPLEQ_INSERT_TAIL(bm_list, bm, entry);
1518         } else {
1519             if (!(bm->flags & BME_FLAG_IN_USE)) {
1520                 error_setg(errp, "Bitmap '%s' already exists in the image",
1521                            name);
1522                 goto fail;
1523             }
1524             tb = g_memdup(&bm->table, sizeof(bm->table));
1525             bm->table.offset = 0;
1526             bm->table.size = 0;
1527             QSIMPLEQ_INSERT_TAIL(&drop_tables, tb, entry);
1528         }
1529         bm->flags = bdrv_dirty_bitmap_enabled(bitmap) ? BME_FLAG_AUTO : 0;
1530         bm->granularity_bits = ctz32(bdrv_dirty_bitmap_granularity(bitmap));
1531         bm->dirty_bitmap = bitmap;
1532     }
1533
1534     /* allocate clusters and store bitmaps */
1535     QSIMPLEQ_FOREACH(bm, bm_list, entry) {
1536         if (bm->dirty_bitmap == NULL) {
1537             continue;
1538         }
1539
1540         ret = store_bitmap(bs, bm, errp);
1541         if (ret < 0) {
1542             goto fail;
1543         }
1544     }
1545
1546     ret = update_ext_header_and_dir(bs, bm_list);
1547     if (ret < 0) {
1548         error_setg_errno(errp, -ret, "Failed to update bitmap extension");
1549         goto fail;
1550     }
1551
1552     /* Bitmap directory was successfully updated, so, old data can be dropped.
1553      * TODO it is better to reuse these clusters */
1554     QSIMPLEQ_FOREACH_SAFE(tb, &drop_tables, entry, tb_next) {
1555         free_bitmap_clusters(bs, tb);
1556         g_free(tb);
1557     }
1558
1559     QSIMPLEQ_FOREACH(bm, bm_list, entry) {
1560         /* For safety, we remove bitmap after storing.
1561          * We may be here in two cases:
1562          * 1. bdrv_close. It's ok to drop bitmap.
1563          * 2. inactivation. It means migration without 'dirty-bitmaps'
1564          *    capability, so bitmaps are not marked with
1565          *    BdrvDirtyBitmap.migration flags. It's not bad to drop them too,
1566          *    and reload on invalidation.
1567          */
1568         if (bm->dirty_bitmap == NULL) {
1569             continue;
1570         }
1571
1572         bdrv_release_dirty_bitmap(bs, bm->dirty_bitmap);
1573     }
1574
1575     bitmap_list_free(bm_list);
1576     return;
1577
1578 fail:
1579     QSIMPLEQ_FOREACH(bm, bm_list, entry) {
1580         if (bm->dirty_bitmap == NULL || bm->table.offset == 0) {
1581             continue;
1582         }
1583
1584         free_bitmap_clusters(bs, &bm->table);
1585     }
1586
1587     QSIMPLEQ_FOREACH_SAFE(tb, &drop_tables, entry, tb_next) {
1588         g_free(tb);
1589     }
1590
1591     bitmap_list_free(bm_list);
1592 }
1593
1594 int qcow2_reopen_bitmaps_ro(BlockDriverState *bs, Error **errp)
1595 {
1596     BdrvDirtyBitmap *bitmap;
1597     Error *local_err = NULL;
1598
1599     qcow2_store_persistent_dirty_bitmaps(bs, &local_err);
1600     if (local_err != NULL) {
1601         error_propagate(errp, local_err);
1602         return -EINVAL;
1603     }
1604
1605     for (bitmap = bdrv_dirty_bitmap_next(bs, NULL); bitmap != NULL;
1606          bitmap = bdrv_dirty_bitmap_next(bs, bitmap))
1607     {
1608         if (bdrv_dirty_bitmap_get_persistence(bitmap)) {
1609             bdrv_dirty_bitmap_set_readonly(bitmap, true);
1610         }
1611     }
1612
1613     return 0;
1614 }
1615
1616 bool qcow2_can_store_new_dirty_bitmap(BlockDriverState *bs,
1617                                       const char *name,
1618                                       uint32_t granularity,
1619                                       Error **errp)
1620 {
1621     BDRVQcow2State *s = bs->opaque;
1622     bool found;
1623     Qcow2BitmapList *bm_list;
1624
1625     if (s->qcow_version < 3) {
1626         /* Without autoclear_features, we would always have to assume
1627          * that a program without persistent dirty bitmap support has
1628          * accessed this qcow2 file when opening it, and would thus
1629          * have to drop all dirty bitmaps (defeating their purpose).
1630          */
1631         error_setg(errp, "Cannot store dirty bitmaps in qcow2 v2 files");
1632         goto fail;
1633     }
1634
1635     if (check_constraints_on_bitmap(bs, name, granularity, errp) != 0) {
1636         goto fail;
1637     }
1638
1639     if (s->nb_bitmaps == 0) {
1640         return true;
1641     }
1642
1643     if (s->nb_bitmaps >= QCOW2_MAX_BITMAPS) {
1644         error_setg(errp,
1645                    "Maximum number of persistent bitmaps is already reached");
1646         goto fail;
1647     }
1648
1649     if (s->bitmap_directory_size + calc_dir_entry_size(strlen(name), 0) >
1650         QCOW2_MAX_BITMAP_DIRECTORY_SIZE)
1651     {
1652         error_setg(errp, "Not enough space in the bitmap directory");
1653         goto fail;
1654     }
1655
1656     bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
1657                                s->bitmap_directory_size, errp);
1658     if (bm_list == NULL) {
1659         goto fail;
1660     }
1661
1662     found = find_bitmap_by_name(bm_list, name);
1663     bitmap_list_free(bm_list);
1664     if (found) {
1665         error_setg(errp, "Bitmap with the same name is already stored");
1666         goto fail;
1667     }
1668
1669     return true;
1670
1671 fail:
1672     error_prepend(errp, "Can't make bitmap '%s' persistent in '%s': ",
1673                   name, bdrv_get_device_or_node_name(bs));
1674     return false;
1675 }