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 "crypto/block.h"
  29 #include "qemu/coroutine.h"
  30 #include "qemu/units.h"
  31
  32 //#define DEBUG_ALLOC
  33 //#define DEBUG_ALLOC2
  34 //#define DEBUG_EXT
  35
  36 #define QCOW_MAGIC (('Q' << 24) | ('F' << 16) | ('I' << 8) | 0xfb)
  37
  38 #define QCOW_CRYPT_NONE 0
  39 #define QCOW_CRYPT_AES  1
  40 #define QCOW_CRYPT_LUKS 2
  41
  42 #define QCOW_MAX_CRYPT_CLUSTERS 32
  43 #define QCOW_MAX_SNAPSHOTS 65536
  44
  45 /* Field widths in qcow2 mean normal cluster offsets cannot reach
  46  * 64PB; depending on cluster size, compressed clusters can have a
  47  * smaller limit (64PB for up to 16k clusters, then ramps down to
  48  * 512TB for 2M clusters).  */
  49 #define QCOW_MAX_CLUSTER_OFFSET ((1ULL << 56) - 1)
  50
  51 /* 8 MB refcount table is enough for 2 PB images at 64k cluster size
  52  * (128 GB for 512 byte clusters, 2 EB for 2 MB clusters) */
  53 #define QCOW_MAX_REFTABLE_SIZE (8 * MiB)
  54
  55 /* 32 MB L1 table is enough for 2 PB images at 64k cluster size
  56  * (128 GB for 512 byte clusters, 2 EB for 2 MB clusters) */
  57 #define QCOW_MAX_L1_SIZE (32 * MiB)
  58
  59 /* Allow for an average of 1k per snapshot table entry, should be plenty of
  60  * space for snapshot names and IDs */
  61 #define QCOW_MAX_SNAPSHOTS_SIZE (1024 * QCOW_MAX_SNAPSHOTS)
  62
  63 /* Bitmap header extension constraints */
  64 #define QCOW2_MAX_BITMAPS 65535
  65 #define QCOW2_MAX_BITMAP_DIRECTORY_SIZE (1024 * QCOW2_MAX_BITMAPS)
  66
  67 /* indicate that the refcount of the referenced cluster is exactly one. */
  68 #define QCOW_OFLAG_COPIED     (1ULL << 63)
  69 /* indicate that the cluster is compressed (they never have the copied flag) */
  70 #define QCOW_OFLAG_COMPRESSED (1ULL << 62)
  71 /* The cluster reads as all zeros */
  72 #define QCOW_OFLAG_ZERO (1ULL << 0)
  73
  74 #define MIN_CLUSTER_BITS 9
  75 #define MAX_CLUSTER_BITS 21
  76
  77 /* Must be at least 2 to cover COW */
  78 #define MIN_L2_CACHE_SIZE 2 /* cache entries */
  79
  80 /* Must be at least 4 to cover all cases of refcount table growth */
  81 #define MIN_REFCOUNT_CACHE_SIZE 4 /* clusters */
  82
  83 #ifdef CONFIG_LINUX
  84 #define DEFAULT_L2_CACHE_MAX_SIZE (32 * MiB)
  85 #define DEFAULT_CACHE_CLEAN_INTERVAL 600  /* seconds */
  86 #else
  87 #define DEFAULT_L2_CACHE_MAX_SIZE (8 * MiB)
  88 /* Cache clean interval is currently available only on Linux, so must be 0 */
  89 #define DEFAULT_CACHE_CLEAN_INTERVAL 0
  90 #endif
  91
  92 #define DEFAULT_CLUSTER_SIZE 65536
  93
  94 #define QCOW2_OPT_LAZY_REFCOUNTS "lazy-refcounts"
  95 #define QCOW2_OPT_DISCARD_REQUEST "pass-discard-request"
  96 #define QCOW2_OPT_DISCARD_SNAPSHOT "pass-discard-snapshot"
  97 #define QCOW2_OPT_DISCARD_OTHER "pass-discard-other"
  98 #define QCOW2_OPT_OVERLAP "overlap-check"
  99 #define QCOW2_OPT_OVERLAP_TEMPLATE "overlap-check.template"
 100 #define QCOW2_OPT_OVERLAP_MAIN_HEADER "overlap-check.main-header"
 101 #define QCOW2_OPT_OVERLAP_ACTIVE_L1 "overlap-check.active-l1"
 102 #define QCOW2_OPT_OVERLAP_ACTIVE_L2 "overlap-check.active-l2"
 103 #define QCOW2_OPT_OVERLAP_REFCOUNT_TABLE "overlap-check.refcount-table"
 104 #define QCOW2_OPT_OVERLAP_REFCOUNT_BLOCK "overlap-check.refcount-block"
 105 #define QCOW2_OPT_OVERLAP_SNAPSHOT_TABLE "overlap-check.snapshot-table"
 106 #define QCOW2_OPT_OVERLAP_INACTIVE_L1 "overlap-check.inactive-l1"
 107 #define QCOW2_OPT_OVERLAP_INACTIVE_L2 "overlap-check.inactive-l2"
 108 #define QCOW2_OPT_OVERLAP_BITMAP_DIRECTORY "overlap-check.bitmap-directory"
 109 #define QCOW2_OPT_CACHE_SIZE "cache-size"
 110 #define QCOW2_OPT_L2_CACHE_SIZE "l2-cache-size"
 111 #define QCOW2_OPT_L2_CACHE_ENTRY_SIZE "l2-cache-entry-size"
 112 #define QCOW2_OPT_REFCOUNT_CACHE_SIZE "refcount-cache-size"
 113 #define QCOW2_OPT_CACHE_CLEAN_INTERVAL "cache-clean-interval"
 114
 115 typedef struct QCowHeader {
 116     uint32_t magic;
 117     uint32_t version;
 118     uint64_t backing_file_offset;
 119     uint32_t backing_file_size;
 120     uint32_t cluster_bits;
 121     uint64_t size; /* in bytes */
 122     uint32_t crypt_method;
 123     uint32_t l1_size; /* XXX: save number of clusters instead ? */
 124     uint64_t l1_table_offset;
 125     uint64_t refcount_table_offset;
 126     uint32_t refcount_table_clusters;
 127     uint32_t nb_snapshots;
 128     uint64_t snapshots_offset;
 129
 130     /* The following fields are only valid for version >= 3 */
 131     uint64_t incompatible_features;
 132     uint64_t compatible_features;
 133     uint64_t autoclear_features;
 134
 135     uint32_t refcount_order;
 136     uint32_t header_length;
 137 } QEMU_PACKED QCowHeader;
 138
 139 typedef struct QEMU_PACKED QCowSnapshotHeader {
 140     /* header is 8 byte aligned */
 141     uint64_t l1_table_offset;
 142
 143     uint32_t l1_size;
 144     uint16_t id_str_size;
 145     uint16_t name_size;
 146
 147     uint32_t date_sec;
 148     uint32_t date_nsec;
 149
 150     uint64_t vm_clock_nsec;
 151
 152     uint32_t vm_state_size;
 153     uint32_t extra_data_size; /* for extension */
 154     /* extra data follows */
 155     /* id_str follows */
 156     /* name follows  */
 157 } QCowSnapshotHeader;
 158
 159 typedef struct QEMU_PACKED QCowSnapshotExtraData {
 160     uint64_t vm_state_size_large;
 161     uint64_t disk_size;
 162 } QCowSnapshotExtraData;
 163
 164
 165 typedef struct QCowSnapshot {
 166     uint64_t l1_table_offset;
 167     uint32_t l1_size;
 168     char *id_str;
 169     char *name;
 170     uint64_t disk_size;
 171     uint64_t vm_state_size;
 172     uint32_t date_sec;
 173     uint32_t date_nsec;
 174     uint64_t vm_clock_nsec;
 175 } QCowSnapshot;
 176
 177 struct Qcow2Cache;
 178 typedef struct Qcow2Cache Qcow2Cache;
 179
 180 typedef struct Qcow2CryptoHeaderExtension {
 181     uint64_t offset;
 182     uint64_t length;
 183 } QEMU_PACKED Qcow2CryptoHeaderExtension;
 184
 185 typedef struct Qcow2UnknownHeaderExtension {
 186     uint32_t magic;
 187     uint32_t len;
 188     QLIST_ENTRY(Qcow2UnknownHeaderExtension) next;
 189     uint8_t data[];
 190 } Qcow2UnknownHeaderExtension;
 191
 192 enum {
 193     QCOW2_FEAT_TYPE_INCOMPATIBLE    = 0,
 194     QCOW2_FEAT_TYPE_COMPATIBLE      = 1,
 195     QCOW2_FEAT_TYPE_AUTOCLEAR       = 2,
 196 };
 197
 198 /* Incompatible feature bits */
 199 enum {
 200     QCOW2_INCOMPAT_DIRTY_BITNR      = 0,
 201     QCOW2_INCOMPAT_CORRUPT_BITNR    = 1,
 202     QCOW2_INCOMPAT_DATA_FILE_BITNR  = 2,
 203     QCOW2_INCOMPAT_DIRTY            = 1 << QCOW2_INCOMPAT_DIRTY_BITNR,
 204     QCOW2_INCOMPAT_CORRUPT          = 1 << QCOW2_INCOMPAT_CORRUPT_BITNR,
 205     QCOW2_INCOMPAT_DATA_FILE        = 1 << QCOW2_INCOMPAT_DATA_FILE_BITNR,
 206
 207     QCOW2_INCOMPAT_MASK             = QCOW2_INCOMPAT_DIRTY
 208                                     | QCOW2_INCOMPAT_CORRUPT,
 209 };
 210
 211 /* Compatible feature bits */
 212 enum {
 213     QCOW2_COMPAT_LAZY_REFCOUNTS_BITNR = 0,
 214     QCOW2_COMPAT_LAZY_REFCOUNTS       = 1 << QCOW2_COMPAT_LAZY_REFCOUNTS_BITNR,
 215
 216     QCOW2_COMPAT_FEAT_MASK            = QCOW2_COMPAT_LAZY_REFCOUNTS,
 217 };
 218
 219 /* Autoclear feature bits */
 220 enum {
 221     QCOW2_AUTOCLEAR_BITMAPS_BITNR       = 0,
 222     QCOW2_AUTOCLEAR_DATA_FILE_RAW_BITNR = 1,
 223     QCOW2_AUTOCLEAR_BITMAPS             = 1 << QCOW2_AUTOCLEAR_BITMAPS_BITNR,
 224     QCOW2_AUTOCLEAR_DATA_FILE_RAW       = 1 << QCOW2_AUTOCLEAR_DATA_FILE_RAW_BITNR,
 225
 226     QCOW2_AUTOCLEAR_MASK                = QCOW2_AUTOCLEAR_BITMAPS,
 227 };
 228
 229 enum qcow2_discard_type {
 230     QCOW2_DISCARD_NEVER = 0,
 231     QCOW2_DISCARD_ALWAYS,
 232     QCOW2_DISCARD_REQUEST,
 233     QCOW2_DISCARD_SNAPSHOT,
 234     QCOW2_DISCARD_OTHER,
 235     QCOW2_DISCARD_MAX
 236 };
 237
 238 typedef struct Qcow2Feature {
 239     uint8_t type;
 240     uint8_t bit;
 241     char    name[46];
 242 } QEMU_PACKED Qcow2Feature;
 243
 244 typedef struct Qcow2DiscardRegion {
 245     BlockDriverState *bs;
 246     uint64_t offset;
 247     uint64_t bytes;
 248     QTAILQ_ENTRY(Qcow2DiscardRegion) next;
 249 } Qcow2DiscardRegion;
 250
 251 typedef uint64_t Qcow2GetRefcountFunc(const void *refcount_array,
 252                                       uint64_t index);
 253 typedef void Qcow2SetRefcountFunc(void *refcount_array,
 254                                   uint64_t index, uint64_t value);
 255
 256 typedef struct Qcow2BitmapHeaderExt {
 257     uint32_t nb_bitmaps;
 258     uint32_t reserved32;
 259     uint64_t bitmap_directory_size;
 260     uint64_t bitmap_directory_offset;
 261 } QEMU_PACKED Qcow2BitmapHeaderExt;
 262
 263 typedef struct BDRVQcow2State {
 264     int cluster_bits;
 265     int cluster_size;
 266     int cluster_sectors;
 267     int l2_slice_size;
 268     int l2_bits;
 269     int l2_size;
 270     int l1_size;
 271     int l1_vm_state_index;
 272     int refcount_block_bits;
 273     int refcount_block_size;
 274     int csize_shift;
 275     int csize_mask;
 276     uint64_t cluster_offset_mask;
 277     uint64_t l1_table_offset;
 278     uint64_t *l1_table;
 279
 280     Qcow2Cache* l2_table_cache;
 281     Qcow2Cache* refcount_block_cache;
 282     QEMUTimer *cache_clean_timer;
 283     unsigned cache_clean_interval;
 284
 285     uint8_t *cluster_cache;
 286     uint8_t *cluster_data;
 287     uint64_t cluster_cache_offset;
 288     QLIST_HEAD(, QCowL2Meta) cluster_allocs;
 289
 290     uint64_t *refcount_table;
 291     uint64_t refcount_table_offset;
 292     uint32_t refcount_table_size;
 293     uint32_t max_refcount_table_index; /* Last used entry in refcount_table */
 294     uint64_t free_cluster_index;
 295     uint64_t free_byte_offset;
 296
 297     CoMutex lock;
 298
 299     Qcow2CryptoHeaderExtension crypto_header; /* QCow2 header extension */
 300     QCryptoBlockOpenOptions *crypto_opts; /* Disk encryption runtime options */
 301     QCryptoBlock *crypto; /* Disk encryption format driver */
 302     bool crypt_physical_offset; /* Whether to use virtual or physical offset
 303                                    for encryption initialization vector tweak */
 304     uint32_t crypt_method_header;
 305     uint64_t snapshots_offset;
 306     int snapshots_size;
 307     unsigned int nb_snapshots;
 308     QCowSnapshot *snapshots;
 309
 310     uint32_t nb_bitmaps;
 311     uint64_t bitmap_directory_size;
 312     uint64_t bitmap_directory_offset;
 313
 314     int flags;
 315     int qcow_version;
 316     bool use_lazy_refcounts;
 317     int refcount_order;
 318     int refcount_bits;
 319     uint64_t refcount_max;
 320
 321     Qcow2GetRefcountFunc *get_refcount;
 322     Qcow2SetRefcountFunc *set_refcount;
 323
 324     bool discard_passthrough[QCOW2_DISCARD_MAX];
 325
 326     int overlap_check; /* bitmask of Qcow2MetadataOverlap values */
 327     bool signaled_corruption;
 328
 329     uint64_t incompatible_features;
 330     uint64_t compatible_features;
 331     uint64_t autoclear_features;
 332
 333     size_t unknown_header_fields_size;
 334     void* unknown_header_fields;
 335     QLIST_HEAD(, Qcow2UnknownHeaderExtension) unknown_header_ext;
 336     QTAILQ_HEAD (, Qcow2DiscardRegion) discards;
 337     bool cache_discards;
 338
 339     /* Backing file path and format as stored in the image (this is not the
 340      * effective path/format, which may be the result of a runtime option
 341      * override) */
 342     char *image_backing_file;
 343     char *image_backing_format;
 344
 345     CoQueue compress_wait_queue;
 346     int nb_compress_threads;
 347
 348     BdrvChild *data_file;
 349 } BDRVQcow2State;
 350
 351 typedef struct Qcow2COWRegion {
 352     /**
 353      * Offset of the COW region in bytes from the start of the first cluster
 354      * touched by the request.
 355      */
 356     unsigned    offset;
 357
 358     /** Number of bytes to copy */
 359     unsigned    nb_bytes;
 360 } Qcow2COWRegion;
 361
 362 /**
 363  * Describes an in-flight (part of a) write request that writes to clusters
 364  * that are not referenced in their L2 table yet.
 365  */
 366 typedef struct QCowL2Meta
 367 {
 368     /** Guest offset of the first newly allocated cluster */
 369     uint64_t offset;
 370
 371     /** Host offset of the first newly allocated cluster */
 372     uint64_t alloc_offset;
 373
 374     /** Number of newly allocated clusters */
 375     int nb_clusters;
 376
 377     /** Do not free the old clusters */
 378     bool keep_old_clusters;
 379
 380     /**
 381      * Requests that overlap with this allocation and wait to be restarted
 382      * when the allocating request has completed.
 383      */
 384     CoQueue dependent_requests;
 385
 386     /**
 387      * The COW Region between the start of the first allocated cluster and the
 388      * area the guest actually writes to.
 389      */
 390     Qcow2COWRegion cow_start;
 391
 392     /**
 393      * The COW Region between the area the guest actually writes to and the
 394      * end of the last allocated cluster.
 395      */
 396     Qcow2COWRegion cow_end;
 397
 398     /**
 399      * The I/O vector with the data from the actual guest write request.
 400      * If non-NULL, this is meant to be merged together with the data
 401      * from @cow_start and @cow_end into one single write operation.
 402      */
 403     QEMUIOVector *data_qiov;
 404
 405     /** Pointer to next L2Meta of the same write request */
 406     struct QCowL2Meta *next;
 407
 408     QLIST_ENTRY(QCowL2Meta) next_in_flight;
 409 } QCowL2Meta;
 410
 411 typedef enum QCow2ClusterType {
 412     QCOW2_CLUSTER_UNALLOCATED,
 413     QCOW2_CLUSTER_ZERO_PLAIN,
 414     QCOW2_CLUSTER_ZERO_ALLOC,
 415     QCOW2_CLUSTER_NORMAL,
 416     QCOW2_CLUSTER_COMPRESSED,
 417 } QCow2ClusterType;
 418
 419 typedef enum QCow2MetadataOverlap {
 420     QCOW2_OL_MAIN_HEADER_BITNR      = 0,
 421     QCOW2_OL_ACTIVE_L1_BITNR        = 1,
 422     QCOW2_OL_ACTIVE_L2_BITNR        = 2,
 423     QCOW2_OL_REFCOUNT_TABLE_BITNR   = 3,
 424     QCOW2_OL_REFCOUNT_BLOCK_BITNR   = 4,
 425     QCOW2_OL_SNAPSHOT_TABLE_BITNR   = 5,
 426     QCOW2_OL_INACTIVE_L1_BITNR      = 6,
 427     QCOW2_OL_INACTIVE_L2_BITNR      = 7,
 428     QCOW2_OL_BITMAP_DIRECTORY_BITNR = 8,
 429
 430     QCOW2_OL_MAX_BITNR              = 9,
 431
 432     QCOW2_OL_NONE             = 0,
 433     QCOW2_OL_MAIN_HEADER      = (1 << QCOW2_OL_MAIN_HEADER_BITNR),
 434     QCOW2_OL_ACTIVE_L1        = (1 << QCOW2_OL_ACTIVE_L1_BITNR),
 435     QCOW2_OL_ACTIVE_L2        = (1 << QCOW2_OL_ACTIVE_L2_BITNR),
 436     QCOW2_OL_REFCOUNT_TABLE   = (1 << QCOW2_OL_REFCOUNT_TABLE_BITNR),
 437     QCOW2_OL_REFCOUNT_BLOCK   = (1 << QCOW2_OL_REFCOUNT_BLOCK_BITNR),
 438     QCOW2_OL_SNAPSHOT_TABLE   = (1 << QCOW2_OL_SNAPSHOT_TABLE_BITNR),
 439     QCOW2_OL_INACTIVE_L1      = (1 << QCOW2_OL_INACTIVE_L1_BITNR),
 440     /* NOTE: Checking overlaps with inactive L2 tables will result in bdrv
 441      * reads. */
 442     QCOW2_OL_INACTIVE_L2      = (1 << QCOW2_OL_INACTIVE_L2_BITNR),
 443     QCOW2_OL_BITMAP_DIRECTORY = (1 << QCOW2_OL_BITMAP_DIRECTORY_BITNR),
 444 } QCow2MetadataOverlap;
 445
 446 /* Perform all overlap checks which can be done in constant time */
 447 #define QCOW2_OL_CONSTANT \
 448     (QCOW2_OL_MAIN_HEADER | QCOW2_OL_ACTIVE_L1 | QCOW2_OL_REFCOUNT_TABLE | \
 449      QCOW2_OL_SNAPSHOT_TABLE | QCOW2_OL_BITMAP_DIRECTORY)
 450
 451 /* Perform all overlap checks which don't require disk access */
 452 #define QCOW2_OL_CACHED \
 453     (QCOW2_OL_CONSTANT | QCOW2_OL_ACTIVE_L2 | QCOW2_OL_REFCOUNT_BLOCK | \
 454      QCOW2_OL_INACTIVE_L1)
 455
 456 /* Perform all overlap checks */
 457 #define QCOW2_OL_ALL \
 458     (QCOW2_OL_CACHED | QCOW2_OL_INACTIVE_L2)
 459
 460 #define L1E_OFFSET_MASK 0x00fffffffffffe00ULL
 461 #define L2E_OFFSET_MASK 0x00fffffffffffe00ULL
 462 #define L2E_COMPRESSED_OFFSET_SIZE_MASK 0x3fffffffffffffffULL
 463
 464 #define REFT_OFFSET_MASK 0xfffffffffffffe00ULL
 465
 466 #define INV_OFFSET (-1ULL)
 467
 468 static inline bool has_data_file(BlockDriverState *bs)
 469 {
 470     BDRVQcow2State *s = bs->opaque;
 471     return (s->data_file != bs->file);
 472 }
 473
 474 static inline int64_t start_of_cluster(BDRVQcow2State *s, int64_t offset)
 475 {
 476     return offset & ~(s->cluster_size - 1);
 477 }
 478
 479 static inline int64_t offset_into_cluster(BDRVQcow2State *s, int64_t offset)
 480 {
 481     return offset & (s->cluster_size - 1);
 482 }
 483
 484 static inline uint64_t size_to_clusters(BDRVQcow2State *s, uint64_t size)
 485 {
 486     return (size + (s->cluster_size - 1)) >> s->cluster_bits;
 487 }
 488
 489 static inline int64_t size_to_l1(BDRVQcow2State *s, int64_t size)
 490 {
 491     int shift = s->cluster_bits + s->l2_bits;
 492     return (size + (1ULL << shift) - 1) >> shift;
 493 }
 494
 495 static inline int offset_to_l1_index(BDRVQcow2State *s, uint64_t offset)
 496 {
 497     return offset >> (s->l2_bits + s->cluster_bits);
 498 }
 499
 500 static inline int offset_to_l2_index(BDRVQcow2State *s, int64_t offset)
 501 {
 502     return (offset >> s->cluster_bits) & (s->l2_size - 1);
 503 }
 504
 505 static inline int offset_to_l2_slice_index(BDRVQcow2State *s, int64_t offset)
 506 {
 507     return (offset >> s->cluster_bits) & (s->l2_slice_size - 1);
 508 }
 509
 510 static inline int64_t qcow2_vm_state_offset(BDRVQcow2State *s)
 511 {
 512     return (int64_t)s->l1_vm_state_index << (s->cluster_bits + s->l2_bits);
 513 }
 514
 515 static inline QCow2ClusterType qcow2_get_cluster_type(BlockDriverState *bs,
 516                                                       uint64_t l2_entry)
 517 {
 518     if (l2_entry & QCOW_OFLAG_COMPRESSED) {
 519         return QCOW2_CLUSTER_COMPRESSED;
 520     } else if (l2_entry & QCOW_OFLAG_ZERO) {
 521         if (l2_entry & L2E_OFFSET_MASK) {
 522             return QCOW2_CLUSTER_ZERO_ALLOC;
 523         }
 524         return QCOW2_CLUSTER_ZERO_PLAIN;
 525     } else if (!(l2_entry & L2E_OFFSET_MASK)) {
 526         /* Offset 0 generally means unallocated, but it is ambiguous with
 527          * external data files because 0 is a valid offset there. However, all
 528          * clusters in external data files always have refcount 1, so we can
 529          * rely on QCOW_OFLAG_COPIED to disambiguate. */
 530         if (has_data_file(bs) && (l2_entry & QCOW_OFLAG_COPIED)) {
 531             return QCOW2_CLUSTER_NORMAL;
 532         } else {
 533             return QCOW2_CLUSTER_UNALLOCATED;
 534         }
 535     } else {
 536         return QCOW2_CLUSTER_NORMAL;
 537     }
 538 }
 539
 540 /* Check whether refcounts are eager or lazy */
 541 static inline bool qcow2_need_accurate_refcounts(BDRVQcow2State *s)
 542 {
 543     return !(s->incompatible_features & QCOW2_INCOMPAT_DIRTY);
 544 }
 545
 546 static inline uint64_t l2meta_cow_start(QCowL2Meta *m)
 547 {
 548     return m->offset + m->cow_start.offset;
 549 }
 550
 551 static inline uint64_t l2meta_cow_end(QCowL2Meta *m)
 552 {
 553     return m->offset + m->cow_end.offset + m->cow_end.nb_bytes;
 554 }
 555
 556 static inline uint64_t refcount_diff(uint64_t r1, uint64_t r2)
 557 {
 558     return r1 > r2 ? r1 - r2 : r2 - r1;
 559 }
 560
 561 static inline
 562 uint32_t offset_to_reftable_index(BDRVQcow2State *s, uint64_t offset)
 563 {
 564     return offset >> (s->refcount_block_bits + s->cluster_bits);
 565 }
 566
 567 /* qcow2.c functions */
 568 int64_t qcow2_refcount_metadata_size(int64_t clusters, size_t cluster_size,
 569                                      int refcount_order, bool generous_increase,
 570                                      uint64_t *refblock_count);
 571
 572 int qcow2_mark_dirty(BlockDriverState *bs);
 573 int qcow2_mark_corrupt(BlockDriverState *bs);
 574 int qcow2_mark_consistent(BlockDriverState *bs);
 575 int qcow2_update_header(BlockDriverState *bs);
 576
 577 void qcow2_signal_corruption(BlockDriverState *bs, bool fatal, int64_t offset,
 578                              int64_t size, const char *message_format, ...)
 579                              GCC_FMT_ATTR(5, 6);
 580
 581 int qcow2_validate_table(BlockDriverState *bs, uint64_t offset,
 582                          uint64_t entries, size_t entry_len,
 583                          int64_t max_size_bytes, const char *table_name,
 584                          Error **errp);
 585
 586 /* qcow2-refcount.c functions */
 587 int qcow2_refcount_init(BlockDriverState *bs);
 588 void qcow2_refcount_close(BlockDriverState *bs);
 589
 590 int qcow2_get_refcount(BlockDriverState *bs, int64_t cluster_index,
 591                        uint64_t *refcount);
 592
 593 int qcow2_update_cluster_refcount(BlockDriverState *bs, int64_t cluster_index,
 594                                   uint64_t addend, bool decrease,
 595                                   enum qcow2_discard_type type);
 596
 597 int64_t qcow2_refcount_area(BlockDriverState *bs, uint64_t offset,
 598                             uint64_t additional_clusters, bool exact_size,
 599                             int new_refblock_index,
 600                             uint64_t new_refblock_offset);
 601
 602 int64_t qcow2_alloc_clusters(BlockDriverState *bs, uint64_t size);
 603 int64_t qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t offset,
 604                                 int64_t nb_clusters);
 605 int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size);
 606 void qcow2_free_clusters(BlockDriverState *bs,
 607                           int64_t offset, int64_t size,
 608                           enum qcow2_discard_type type);
 609 void qcow2_free_any_clusters(BlockDriverState *bs, uint64_t l2_entry,
 610                              int nb_clusters, enum qcow2_discard_type type);
 611
 612 int qcow2_update_snapshot_refcount(BlockDriverState *bs,
 613     int64_t l1_table_offset, int l1_size, int addend);
 614
 615 int coroutine_fn qcow2_flush_caches(BlockDriverState *bs);
 616 int coroutine_fn qcow2_write_caches(BlockDriverState *bs);
 617 int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
 618                           BdrvCheckMode fix);
 619
 620 void qcow2_process_discards(BlockDriverState *bs, int ret);
 621
 622 int qcow2_check_metadata_overlap(BlockDriverState *bs, int ign, int64_t offset,
 623                                  int64_t size);
 624 int qcow2_pre_write_overlap_check(BlockDriverState *bs, int ign, int64_t offset,
 625                                   int64_t size);
 626 int qcow2_inc_refcounts_imrt(BlockDriverState *bs, BdrvCheckResult *res,
 627                              void **refcount_table,
 628                              int64_t *refcount_table_size,
 629                              int64_t offset, int64_t size);
 630
 631 int qcow2_change_refcount_order(BlockDriverState *bs, int refcount_order,
 632                                 BlockDriverAmendStatusCB *status_cb,
 633                                 void *cb_opaque, Error **errp);
 634 int qcow2_shrink_reftable(BlockDriverState *bs);
 635 int64_t qcow2_get_last_cluster(BlockDriverState *bs, int64_t size);
 636
 637 /* qcow2-cluster.c functions */
 638 int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size,
 639                         bool exact_size);
 640 int qcow2_shrink_l1_table(BlockDriverState *bs, uint64_t max_size);
 641 int qcow2_write_l1_entry(BlockDriverState *bs, int l1_index);
 642 int qcow2_encrypt_sectors(BDRVQcow2State *s, int64_t sector_num,
 643                           uint8_t *buf, int nb_sectors, bool enc, Error **errp);
 644
 645 int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset,
 646                              unsigned int *bytes, uint64_t *cluster_offset);
 647 int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset,
 648                                unsigned int *bytes, uint64_t *host_offset,
 649                                QCowL2Meta **m);
 650 int qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs,
 651                                           uint64_t offset,
 652                                           int compressed_size,
 653                                           uint64_t *host_offset);
 654
 655 int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m);
 656 void qcow2_alloc_cluster_abort(BlockDriverState *bs, QCowL2Meta *m);
 657 int qcow2_cluster_discard(BlockDriverState *bs, uint64_t offset,
 658                           uint64_t bytes, enum qcow2_discard_type type,
 659                           bool full_discard);
 660 int qcow2_cluster_zeroize(BlockDriverState *bs, uint64_t offset,
 661                           uint64_t bytes, int flags);
 662
 663 int qcow2_expand_zero_clusters(BlockDriverState *bs,
 664                                BlockDriverAmendStatusCB *status_cb,
 665                                void *cb_opaque);
 666
 667 /* qcow2-snapshot.c functions */
 668 int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info);
 669 int qcow2_snapshot_goto(BlockDriverState *bs, const char *snapshot_id);
 670 int qcow2_snapshot_delete(BlockDriverState *bs,
 671                           const char *snapshot_id,
 672                           const char *name,
 673                           Error **errp);
 674 int qcow2_snapshot_list(BlockDriverState *bs, QEMUSnapshotInfo **psn_tab);
 675 int qcow2_snapshot_load_tmp(BlockDriverState *bs,
 676                             const char *snapshot_id,
 677                             const char *name,
 678                             Error **errp);
 679
 680 void qcow2_free_snapshots(BlockDriverState *bs);
 681 int qcow2_read_snapshots(BlockDriverState *bs);
 682
 683 /* qcow2-cache.c functions */
 684 Qcow2Cache *qcow2_cache_create(BlockDriverState *bs, int num_tables,
 685                                unsigned table_size);
 686 int qcow2_cache_destroy(Qcow2Cache *c);
 687
 688 void qcow2_cache_entry_mark_dirty(Qcow2Cache *c, void *table);
 689 int qcow2_cache_flush(BlockDriverState *bs, Qcow2Cache *c);
 690 int qcow2_cache_write(BlockDriverState *bs, Qcow2Cache *c);
 691 int qcow2_cache_set_dependency(BlockDriverState *bs, Qcow2Cache *c,
 692     Qcow2Cache *dependency);
 693 void qcow2_cache_depends_on_flush(Qcow2Cache *c);
 694
 695 void qcow2_cache_clean_unused(Qcow2Cache *c);
 696 int qcow2_cache_empty(BlockDriverState *bs, Qcow2Cache *c);
 697
 698 int qcow2_cache_get(BlockDriverState *bs, Qcow2Cache *c, uint64_t offset,
 699     void **table);
 700 int qcow2_cache_get_empty(BlockDriverState *bs, Qcow2Cache *c, uint64_t offset,
 701     void **table);
 702 void qcow2_cache_put(Qcow2Cache *c, void **table);
 703 void *qcow2_cache_is_table_offset(Qcow2Cache *c, uint64_t offset);
 704 void qcow2_cache_discard(Qcow2Cache *c, void *table);
 705
 706 /* qcow2-bitmap.c functions */
 707 int qcow2_check_bitmaps_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
 708                                   void **refcount_table,
 709                                   int64_t *refcount_table_size);
 710 bool qcow2_load_dirty_bitmaps(BlockDriverState *bs, Error **errp);
 711 Qcow2BitmapInfoList *qcow2_get_bitmap_info_list(BlockDriverState *bs,
 712                                                 Error **errp);
 713 int qcow2_reopen_bitmaps_rw_hint(BlockDriverState *bs, bool *header_updated,
 714                                  Error **errp);
 715 int qcow2_reopen_bitmaps_rw(BlockDriverState *bs, Error **errp);
 716 void qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs, Error **errp);
 717 int qcow2_reopen_bitmaps_ro(BlockDriverState *bs, Error **errp);
 718 bool qcow2_can_store_new_dirty_bitmap(BlockDriverState *bs,
 719                                       const char *name,
 720                                       uint32_t granularity,
 721                                       Error **errp);
 722 void qcow2_remove_persistent_dirty_bitmap(BlockDriverState *bs,
 723                                           const char *name,
 724                                           Error **errp);
 725
 726 #endif