block/qcow2.h

   1 /*
   2  * Block driver for the QCOW version 2 format
   3  *
   4  * Copyright (c) 2004-2006 Fabrice Bellard
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22  * THE SOFTWARE.
  23  */
  24
  25 #ifndef BLOCK_QCOW2_H
  26 #define BLOCK_QCOW2_H
  27
  28 #include "qemu/aes.h"
  29 #include "block/coroutine.h"
  30
  31 //#define DEBUG_ALLOC
  32 //#define DEBUG_ALLOC2
  33 //#define DEBUG_EXT
  34
  35 #define QCOW_MAGIC (('Q' << 24) | ('F' << 16) | ('I' << 8) | 0xfb)
  36
  37 #define QCOW_CRYPT_NONE 0
  38 #define QCOW_CRYPT_AES  1
  39
  40 #define QCOW_MAX_CRYPT_CLUSTERS 32
  41 #define QCOW_MAX_SNAPSHOTS 65536
  42
  43 /* 8 MB refcount table is enough for 2 PB images at 64k cluster size
  44  * (128 GB for 512 byte clusters, 2 EB for 2 MB clusters) */
  45 #define QCOW_MAX_REFTABLE_SIZE 0x800000
  46
  47 /* indicate that the refcount of the referenced cluster is exactly one. */
  48 #define QCOW_OFLAG_COPIED     (1ULL << 63)
  49 /* indicate that the cluster is compressed (they never have the copied flag) */
  50 #define QCOW_OFLAG_COMPRESSED (1ULL << 62)
  51 /* The cluster reads as all zeros */
  52 #define QCOW_OFLAG_ZERO (1ULL << 0)
  53
  54 #define REFCOUNT_SHIFT 1 /* refcount size is 2 bytes */
  55
  56 #define MIN_CLUSTER_BITS 9
  57 #define MAX_CLUSTER_BITS 21
  58
  59 #define L2_CACHE_SIZE 16
  60
  61 /* Must be at least 4 to cover all cases of refcount table growth */
  62 #define REFCOUNT_CACHE_SIZE 4
  63
  64 #define DEFAULT_CLUSTER_SIZE 65536
  65
  66
  67 #define QCOW2_OPT_LAZY_REFCOUNTS "lazy-refcounts"
  68 #define QCOW2_OPT_DISCARD_REQUEST "pass-discard-request"
  69 #define QCOW2_OPT_DISCARD_SNAPSHOT "pass-discard-snapshot"
  70 #define QCOW2_OPT_DISCARD_OTHER "pass-discard-other"
  71 #define QCOW2_OPT_OVERLAP "overlap-check"
  72 #define QCOW2_OPT_OVERLAP_MAIN_HEADER "overlap-check.main-header"
  73 #define QCOW2_OPT_OVERLAP_ACTIVE_L1 "overlap-check.active-l1"
  74 #define QCOW2_OPT_OVERLAP_ACTIVE_L2 "overlap-check.active-l2"
  75 #define QCOW2_OPT_OVERLAP_REFCOUNT_TABLE "overlap-check.refcount-table"
  76 #define QCOW2_OPT_OVERLAP_REFCOUNT_BLOCK "overlap-check.refcount-block"
  77 #define QCOW2_OPT_OVERLAP_SNAPSHOT_TABLE "overlap-check.snapshot-table"
  78 #define QCOW2_OPT_OVERLAP_INACTIVE_L1 "overlap-check.inactive-l1"
  79 #define QCOW2_OPT_OVERLAP_INACTIVE_L2 "overlap-check.inactive-l2"
  80
  81 typedef struct QCowHeader {
  82     uint32_t magic;
  83     uint32_t version;
  84     uint64_t backing_file_offset;
  85     uint32_t backing_file_size;
  86     uint32_t cluster_bits;
  87     uint64_t size; /* in bytes */
  88     uint32_t crypt_method;
  89     uint32_t l1_size; /* XXX: save number of clusters instead ? */
  90     uint64_t l1_table_offset;
  91     uint64_t refcount_table_offset;
  92     uint32_t refcount_table_clusters;
  93     uint32_t nb_snapshots;
  94     uint64_t snapshots_offset;
  95
  96     /* The following fields are only valid for version >= 3 */
  97     uint64_t incompatible_features;
  98     uint64_t compatible_features;
  99     uint64_t autoclear_features;
 100
 101     uint32_t refcount_order;
 102     uint32_t header_length;
 103 } QEMU_PACKED QCowHeader;
 104
 105 typedef struct QEMU_PACKED QCowSnapshotHeader {
 106     /* header is 8 byte aligned */
 107     uint64_t l1_table_offset;
 108
 109     uint32_t l1_size;
 110     uint16_t id_str_size;
 111     uint16_t name_size;
 112
 113     uint32_t date_sec;
 114     uint32_t date_nsec;
 115
 116     uint64_t vm_clock_nsec;
 117
 118     uint32_t vm_state_size;
 119     uint32_t extra_data_size; /* for extension */
 120     /* extra data follows */
 121     /* id_str follows */
 122     /* name follows  */
 123 } QCowSnapshotHeader;
 124
 125 typedef struct QEMU_PACKED QCowSnapshotExtraData {
 126     uint64_t vm_state_size_large;
 127     uint64_t disk_size;
 128 } QCowSnapshotExtraData;
 129
 130
 131 typedef struct QCowSnapshot {
 132     uint64_t l1_table_offset;
 133     uint32_t l1_size;
 134     char *id_str;
 135     char *name;
 136     uint64_t disk_size;
 137     uint64_t vm_state_size;
 138     uint32_t date_sec;
 139     uint32_t date_nsec;
 140     uint64_t vm_clock_nsec;
 141 } QCowSnapshot;
 142
 143 struct Qcow2Cache;
 144 typedef struct Qcow2Cache Qcow2Cache;
 145
 146 typedef struct Qcow2UnknownHeaderExtension {
 147     uint32_t magic;
 148     uint32_t len;
 149     QLIST_ENTRY(Qcow2UnknownHeaderExtension) next;
 150     uint8_t data[];
 151 } Qcow2UnknownHeaderExtension;
 152
 153 enum {
 154     QCOW2_FEAT_TYPE_INCOMPATIBLE    = 0,
 155     QCOW2_FEAT_TYPE_COMPATIBLE      = 1,
 156     QCOW2_FEAT_TYPE_AUTOCLEAR       = 2,
 157 };
 158
 159 /* Incompatible feature bits */
 160 enum {
 161     QCOW2_INCOMPAT_DIRTY_BITNR   = 0,
 162     QCOW2_INCOMPAT_CORRUPT_BITNR = 1,
 163     QCOW2_INCOMPAT_DIRTY         = 1 << QCOW2_INCOMPAT_DIRTY_BITNR,
 164     QCOW2_INCOMPAT_CORRUPT       = 1 << QCOW2_INCOMPAT_CORRUPT_BITNR,
 165
 166     QCOW2_INCOMPAT_MASK          = QCOW2_INCOMPAT_DIRTY
 167                                  | QCOW2_INCOMPAT_CORRUPT,
 168 };
 169
 170 /* Compatible feature bits */
 171 enum {
 172     QCOW2_COMPAT_LAZY_REFCOUNTS_BITNR = 0,
 173     QCOW2_COMPAT_LAZY_REFCOUNTS       = 1 << QCOW2_COMPAT_LAZY_REFCOUNTS_BITNR,
 174
 175     QCOW2_COMPAT_FEAT_MASK            = QCOW2_COMPAT_LAZY_REFCOUNTS,
 176 };
 177
 178 enum qcow2_discard_type {
 179     QCOW2_DISCARD_NEVER = 0,
 180     QCOW2_DISCARD_ALWAYS,
 181     QCOW2_DISCARD_REQUEST,
 182     QCOW2_DISCARD_SNAPSHOT,
 183     QCOW2_DISCARD_OTHER,
 184     QCOW2_DISCARD_MAX
 185 };
 186
 187 typedef struct Qcow2Feature {
 188     uint8_t type;
 189     uint8_t bit;
 190     char    name[46];
 191 } QEMU_PACKED Qcow2Feature;
 192
 193 typedef struct Qcow2DiscardRegion {
 194     BlockDriverState *bs;
 195     uint64_t offset;
 196     uint64_t bytes;
 197     QTAILQ_ENTRY(Qcow2DiscardRegion) next;
 198 } Qcow2DiscardRegion;
 199
 200 typedef struct BDRVQcowState {
 201     int cluster_bits;
 202     int cluster_size;
 203     int cluster_sectors;
 204     int l2_bits;
 205     int l2_size;
 206     int l1_size;
 207     int l1_vm_state_index;
 208     int csize_shift;
 209     int csize_mask;
 210     uint64_t cluster_offset_mask;
 211     uint64_t l1_table_offset;
 212     uint64_t *l1_table;
 213
 214     Qcow2Cache* l2_table_cache;
 215     Qcow2Cache* refcount_block_cache;
 216
 217     uint8_t *cluster_cache;
 218     uint8_t *cluster_data;
 219     uint64_t cluster_cache_offset;
 220     QLIST_HEAD(QCowClusterAlloc, QCowL2Meta) cluster_allocs;
 221
 222     uint64_t *refcount_table;
 223     uint64_t refcount_table_offset;
 224     uint32_t refcount_table_size;
 225     uint64_t free_cluster_index;
 226     uint64_t free_byte_offset;
 227
 228     CoMutex lock;
 229
 230     uint32_t crypt_method; /* current crypt method, 0 if no key yet */
 231     uint32_t crypt_method_header;
 232     AES_KEY aes_encrypt_key;
 233     AES_KEY aes_decrypt_key;
 234     uint64_t snapshots_offset;
 235     int snapshots_size;
 236     unsigned int nb_snapshots;
 237     QCowSnapshot *snapshots;
 238
 239     int flags;
 240     int qcow_version;
 241     bool use_lazy_refcounts;
 242     int refcount_order;
 243
 244     bool discard_passthrough[QCOW2_DISCARD_MAX];
 245
 246     int overlap_check; /* bitmask of Qcow2MetadataOverlap values */
 247
 248     uint64_t incompatible_features;
 249     uint64_t compatible_features;
 250     uint64_t autoclear_features;
 251
 252     size_t unknown_header_fields_size;
 253     void* unknown_header_fields;
 254     QLIST_HEAD(, Qcow2UnknownHeaderExtension) unknown_header_ext;
 255     QTAILQ_HEAD (, Qcow2DiscardRegion) discards;
 256     bool cache_discards;
 257 } BDRVQcowState;
 258
 259 /* XXX: use std qcow open function ? */
 260 typedef struct QCowCreateState {
 261     int cluster_size;
 262     int cluster_bits;
 263     uint16_t *refcount_block;
 264     uint64_t *refcount_table;
 265     int64_t l1_table_offset;
 266     int64_t refcount_table_offset;
 267     int64_t refcount_block_offset;
 268 } QCowCreateState;
 269
 270 struct QCowAIOCB;
 271
 272 typedef struct Qcow2COWRegion {
 273     /**
 274      * Offset of the COW region in bytes from the start of the first cluster
 275      * touched by the request.
 276      */
 277     uint64_t    offset;
 278
 279     /** Number of sectors to copy */
 280     int         nb_sectors;
 281 } Qcow2COWRegion;
 282
 283 /**
 284  * Describes an in-flight (part of a) write request that writes to clusters
 285  * that are not referenced in their L2 table yet.
 286  */
 287 typedef struct QCowL2Meta
 288 {
 289     /** Guest offset of the first newly allocated cluster */
 290     uint64_t offset;
 291
 292     /** Host offset of the first newly allocated cluster */
 293     uint64_t alloc_offset;
 294
 295     /**
 296      * Number of sectors from the start of the first allocated cluster to
 297      * the end of the (possibly shortened) request
 298      */
 299     int nb_available;
 300
 301     /** Number of newly allocated clusters */
 302     int nb_clusters;
 303
 304     /**
 305      * Requests that overlap with this allocation and wait to be restarted
 306      * when the allocating request has completed.
 307      */
 308     CoQueue dependent_requests;
 309
 310     /**
 311      * The COW Region between the start of the first allocated cluster and the
 312      * area the guest actually writes to.
 313      */
 314     Qcow2COWRegion cow_start;
 315
 316     /**
 317      * The COW Region between the area the guest actually writes to and the
 318      * end of the last allocated cluster.
 319      */
 320     Qcow2COWRegion cow_end;
 321
 322     /** Pointer to next L2Meta of the same write request */
 323     struct QCowL2Meta *next;
 324
 325     QLIST_ENTRY(QCowL2Meta) next_in_flight;
 326 } QCowL2Meta;
 327
 328 enum {
 329     QCOW2_CLUSTER_UNALLOCATED,
 330     QCOW2_CLUSTER_NORMAL,
 331     QCOW2_CLUSTER_COMPRESSED,
 332     QCOW2_CLUSTER_ZERO
 333 };
 334
 335 typedef enum QCow2MetadataOverlap {
 336     QCOW2_OL_MAIN_HEADER_BITNR    = 0,
 337     QCOW2_OL_ACTIVE_L1_BITNR      = 1,
 338     QCOW2_OL_ACTIVE_L2_BITNR      = 2,
 339     QCOW2_OL_REFCOUNT_TABLE_BITNR = 3,
 340     QCOW2_OL_REFCOUNT_BLOCK_BITNR = 4,
 341     QCOW2_OL_SNAPSHOT_TABLE_BITNR = 5,
 342     QCOW2_OL_INACTIVE_L1_BITNR    = 6,
 343     QCOW2_OL_INACTIVE_L2_BITNR    = 7,
 344
 345     QCOW2_OL_MAX_BITNR            = 8,
 346
 347     QCOW2_OL_NONE           = 0,
 348     QCOW2_OL_MAIN_HEADER    = (1 << QCOW2_OL_MAIN_HEADER_BITNR),
 349     QCOW2_OL_ACTIVE_L1      = (1 << QCOW2_OL_ACTIVE_L1_BITNR),
 350     QCOW2_OL_ACTIVE_L2      = (1 << QCOW2_OL_ACTIVE_L2_BITNR),
 351     QCOW2_OL_REFCOUNT_TABLE = (1 << QCOW2_OL_REFCOUNT_TABLE_BITNR),
 352     QCOW2_OL_REFCOUNT_BLOCK = (1 << QCOW2_OL_REFCOUNT_BLOCK_BITNR),
 353     QCOW2_OL_SNAPSHOT_TABLE = (1 << QCOW2_OL_SNAPSHOT_TABLE_BITNR),
 354     QCOW2_OL_INACTIVE_L1    = (1 << QCOW2_OL_INACTIVE_L1_BITNR),
 355     /* NOTE: Checking overlaps with inactive L2 tables will result in bdrv
 356      * reads. */
 357     QCOW2_OL_INACTIVE_L2    = (1 << QCOW2_OL_INACTIVE_L2_BITNR),
 358 } QCow2MetadataOverlap;
 359
 360 /* Perform all overlap checks which can be done in constant time */
 361 #define QCOW2_OL_CONSTANT \
 362     (QCOW2_OL_MAIN_HEADER | QCOW2_OL_ACTIVE_L1 | QCOW2_OL_REFCOUNT_TABLE | \
 363      QCOW2_OL_SNAPSHOT_TABLE)
 364
 365 /* Perform all overlap checks which don't require disk access */
 366 #define QCOW2_OL_CACHED \
 367     (QCOW2_OL_CONSTANT | QCOW2_OL_ACTIVE_L2 | QCOW2_OL_REFCOUNT_BLOCK | \
 368      QCOW2_OL_INACTIVE_L1)
 369
 370 /* Perform all overlap checks */
 371 #define QCOW2_OL_ALL \
 372     (QCOW2_OL_CACHED | QCOW2_OL_INACTIVE_L2)
 373
 374 #define L1E_OFFSET_MASK 0x00fffffffffffe00ULL
 375 #define L2E_OFFSET_MASK 0x00fffffffffffe00ULL
 376 #define L2E_COMPRESSED_OFFSET_SIZE_MASK 0x3fffffffffffffffULL
 377
 378 #define REFT_OFFSET_MASK 0xfffffffffffffe00ULL
 379
 380 static inline int64_t start_of_cluster(BDRVQcowState *s, int64_t offset)
 381 {
 382     return offset & ~(s->cluster_size - 1);
 383 }
 384
 385 static inline int64_t offset_into_cluster(BDRVQcowState *s, int64_t offset)
 386 {
 387     return offset & (s->cluster_size - 1);
 388 }
 389
 390 static inline int size_to_clusters(BDRVQcowState *s, int64_t size)
 391 {
 392     return (size + (s->cluster_size - 1)) >> s->cluster_bits;
 393 }
 394
 395 static inline int64_t size_to_l1(BDRVQcowState *s, int64_t size)
 396 {
 397     int shift = s->cluster_bits + s->l2_bits;
 398     return (size + (1ULL << shift) - 1) >> shift;
 399 }
 400
 401 static inline int offset_to_l2_index(BDRVQcowState *s, int64_t offset)
 402 {
 403     return (offset >> s->cluster_bits) & (s->l2_size - 1);
 404 }
 405
 406 static inline int64_t align_offset(int64_t offset, int n)
 407 {
 408     offset = (offset + n - 1) & ~(n - 1);
 409     return offset;
 410 }
 411
 412 static inline int64_t qcow2_vm_state_offset(BDRVQcowState *s)
 413 {
 414     return (int64_t)s->l1_vm_state_index << (s->cluster_bits + s->l2_bits);
 415 }
 416
 417 static inline uint64_t qcow2_max_refcount_clusters(BDRVQcowState *s)
 418 {
 419     return QCOW_MAX_REFTABLE_SIZE >> s->cluster_bits;
 420 }
 421
 422 static inline int qcow2_get_cluster_type(uint64_t l2_entry)
 423 {
 424     if (l2_entry & QCOW_OFLAG_COMPRESSED) {
 425         return QCOW2_CLUSTER_COMPRESSED;
 426     } else if (l2_entry & QCOW_OFLAG_ZERO) {
 427         return QCOW2_CLUSTER_ZERO;
 428     } else if (!(l2_entry & L2E_OFFSET_MASK)) {
 429         return QCOW2_CLUSTER_UNALLOCATED;
 430     } else {
 431         return QCOW2_CLUSTER_NORMAL;
 432     }
 433 }
 434
 435 /* Check whether refcounts are eager or lazy */
 436 static inline bool qcow2_need_accurate_refcounts(BDRVQcowState *s)
 437 {
 438     return !(s->incompatible_features & QCOW2_INCOMPAT_DIRTY);
 439 }
 440
 441 static inline uint64_t l2meta_cow_start(QCowL2Meta *m)
 442 {
 443     return m->offset + m->cow_start.offset;
 444 }
 445
 446 static inline uint64_t l2meta_cow_end(QCowL2Meta *m)
 447 {
 448     return m->offset + m->cow_end.offset
 449         + (m->cow_end.nb_sectors << BDRV_SECTOR_BITS);
 450 }
 451
 452 // FIXME Need qcow2_ prefix to global functions
 453
 454 /* qcow2.c functions */
 455 int qcow2_backing_read1(BlockDriverState *bs, QEMUIOVector *qiov,
 456                   int64_t sector_num, int nb_sectors);
 457
 458 int qcow2_mark_dirty(BlockDriverState *bs);
 459 int qcow2_mark_corrupt(BlockDriverState *bs);
 460 int qcow2_mark_consistent(BlockDriverState *bs);
 461 int qcow2_update_header(BlockDriverState *bs);
 462
 463 /* qcow2-refcount.c functions */
 464 int qcow2_refcount_init(BlockDriverState *bs);
 465 void qcow2_refcount_close(BlockDriverState *bs);
 466
 467 int qcow2_update_cluster_refcount(BlockDriverState *bs, int64_t cluster_index,
 468                                   int addend, enum qcow2_discard_type type);
 469
 470 int64_t qcow2_alloc_clusters(BlockDriverState *bs, uint64_t size);
 471 int qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t offset,
 472     int nb_clusters);
 473 int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size);
 474 void qcow2_free_clusters(BlockDriverState *bs,
 475                           int64_t offset, int64_t size,
 476                           enum qcow2_discard_type type);
 477 void qcow2_free_any_clusters(BlockDriverState *bs, uint64_t l2_entry,
 478                              int nb_clusters, enum qcow2_discard_type type);
 479
 480 int qcow2_update_snapshot_refcount(BlockDriverState *bs,
 481     int64_t l1_table_offset, int l1_size, int addend);
 482
 483 int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
 484                           BdrvCheckMode fix);
 485
 486 void qcow2_process_discards(BlockDriverState *bs, int ret);
 487
 488 int qcow2_check_metadata_overlap(BlockDriverState *bs, int ign, int64_t offset,
 489                                  int64_t size);
 490 int qcow2_pre_write_overlap_check(BlockDriverState *bs, int ign, int64_t offset,
 491                                   int64_t size);
 492
 493 /* qcow2-cluster.c functions */
 494 int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size,
 495                         bool exact_size);
 496 int qcow2_write_l1_entry(BlockDriverState *bs, int l1_index);
 497 void qcow2_l2_cache_reset(BlockDriverState *bs);
 498 int qcow2_decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset);
 499 void qcow2_encrypt_sectors(BDRVQcowState *s, int64_t sector_num,
 500                      uint8_t *out_buf, const uint8_t *in_buf,
 501                      int nb_sectors, int enc,
 502                      const AES_KEY *key);
 503
 504 int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset,
 505     int *num, uint64_t *cluster_offset);
 506 int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset,
 507     int *num, uint64_t *host_offset, QCowL2Meta **m);
 508 uint64_t qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs,
 509                                          uint64_t offset,
 510                                          int compressed_size);
 511
 512 int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m);
 513 int qcow2_discard_clusters(BlockDriverState *bs, uint64_t offset,
 514     int nb_sectors, enum qcow2_discard_type type);
 515 int qcow2_zero_clusters(BlockDriverState *bs, uint64_t offset, int nb_sectors);
 516
 517 int qcow2_expand_zero_clusters(BlockDriverState *bs);
 518
 519 /* qcow2-snapshot.c functions */
 520 int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info);
 521 int qcow2_snapshot_goto(BlockDriverState *bs, const char *snapshot_id);
 522 int qcow2_snapshot_delete(BlockDriverState *bs,
 523                           const char *snapshot_id,
 524                           const char *name,
 525                           Error **errp);
 526 int qcow2_snapshot_list(BlockDriverState *bs, QEMUSnapshotInfo **psn_tab);
 527 int qcow2_snapshot_load_tmp(BlockDriverState *bs,
 528                             const char *snapshot_id,
 529                             const char *name,
 530                             Error **errp);
 531
 532 void qcow2_free_snapshots(BlockDriverState *bs);
 533 int qcow2_read_snapshots(BlockDriverState *bs);
 534
 535 /* qcow2-cache.c functions */
 536 Qcow2Cache *qcow2_cache_create(BlockDriverState *bs, int num_tables);
 537 int qcow2_cache_destroy(BlockDriverState* bs, Qcow2Cache *c);
 538
 539 void qcow2_cache_entry_mark_dirty(Qcow2Cache *c, void *table);
 540 int qcow2_cache_flush(BlockDriverState *bs, Qcow2Cache *c);
 541 int qcow2_cache_set_dependency(BlockDriverState *bs, Qcow2Cache *c,
 542     Qcow2Cache *dependency);
 543 void qcow2_cache_depends_on_flush(Qcow2Cache *c);
 544
 545 int qcow2_cache_empty(BlockDriverState *bs, Qcow2Cache *c);
 546
 547 int qcow2_cache_get(BlockDriverState *bs, Qcow2Cache *c, uint64_t offset,
 548     void **table);
 549 int qcow2_cache_get_empty(BlockDriverState *bs, Qcow2Cache *c, uint64_t offset,
 550     void **table);
 551 int qcow2_cache_put(BlockDriverState *bs, Qcow2Cache *c, void **table);
 552
 553 #endif