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