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
  67 typedef struct QCowHeader {
  68     uint32_t magic;
  69     uint32_t version;
  70     uint64_t backing_file_offset;
  71     uint32_t backing_file_size;
  72     uint32_t cluster_bits;
  73     uint64_t size; /* in bytes */
  74     uint32_t crypt_method;
  75     uint32_t l1_size; /* XXX: save number of clusters instead ? */
  76     uint64_t l1_table_offset;
  77     uint64_t refcount_table_offset;
  78     uint32_t refcount_table_clusters;
  79     uint32_t nb_snapshots;
  80     uint64_t snapshots_offset;
  81
  82     /* The following fields are only valid for version >= 3 */
  83     uint64_t incompatible_features;
  84     uint64_t compatible_features;
  85     uint64_t autoclear_features;
  86
  87     uint32_t refcount_order;
  88     uint32_t header_length;
  89 } QEMU_PACKED QCowHeader;
  90
  91 typedef struct QCowSnapshot {
  92     uint64_t l1_table_offset;
  93     uint32_t l1_size;
  94     char *id_str;
  95     char *name;
  96     uint64_t disk_size;
  97     uint64_t vm_state_size;
  98     uint32_t date_sec;
  99     uint32_t date_nsec;
 100     uint64_t vm_clock_nsec;
 101 } QCowSnapshot;
 102
 103 struct Qcow2Cache;
 104 typedef struct Qcow2Cache Qcow2Cache;
 105
 106 typedef struct Qcow2UnknownHeaderExtension {
 107     uint32_t magic;
 108     uint32_t len;
 109     QLIST_ENTRY(Qcow2UnknownHeaderExtension) next;
 110     uint8_t data[];
 111 } Qcow2UnknownHeaderExtension;
 112
 113 enum {
 114     QCOW2_FEAT_TYPE_INCOMPATIBLE    = 0,
 115     QCOW2_FEAT_TYPE_COMPATIBLE      = 1,
 116     QCOW2_FEAT_TYPE_AUTOCLEAR       = 2,
 117 };
 118
 119 /* Incompatible feature bits */
 120 enum {
 121     QCOW2_INCOMPAT_DIRTY_BITNR   = 0,
 122     QCOW2_INCOMPAT_CORRUPT_BITNR = 1,
 123     QCOW2_INCOMPAT_DIRTY         = 1 << QCOW2_INCOMPAT_DIRTY_BITNR,
 124     QCOW2_INCOMPAT_CORRUPT       = 1 << QCOW2_INCOMPAT_CORRUPT_BITNR,
 125
 126     QCOW2_INCOMPAT_MASK          = QCOW2_INCOMPAT_DIRTY
 127                                  | QCOW2_INCOMPAT_CORRUPT,
 128 };
 129
 130 /* Compatible feature bits */
 131 enum {
 132     QCOW2_COMPAT_LAZY_REFCOUNTS_BITNR = 0,
 133     QCOW2_COMPAT_LAZY_REFCOUNTS       = 1 << QCOW2_COMPAT_LAZY_REFCOUNTS_BITNR,
 134
 135     QCOW2_COMPAT_FEAT_MASK            = QCOW2_COMPAT_LAZY_REFCOUNTS,
 136 };
 137
 138 enum qcow2_discard_type {
 139     QCOW2_DISCARD_NEVER = 0,
 140     QCOW2_DISCARD_ALWAYS,
 141     QCOW2_DISCARD_REQUEST,
 142     QCOW2_DISCARD_SNAPSHOT,
 143     QCOW2_DISCARD_OTHER,
 144     QCOW2_DISCARD_MAX
 145 };
 146
 147 typedef struct Qcow2Feature {
 148     uint8_t type;
 149     uint8_t bit;
 150     char    name[46];
 151 } QEMU_PACKED Qcow2Feature;
 152
 153 typedef struct Qcow2DiscardRegion {
 154     BlockDriverState *bs;
 155     uint64_t offset;
 156     uint64_t bytes;
 157     QTAILQ_ENTRY(Qcow2DiscardRegion) next;
 158 } Qcow2DiscardRegion;
 159
 160 typedef struct BDRVQcowState {
 161     int cluster_bits;
 162     int cluster_size;
 163     int cluster_sectors;
 164     int l2_bits;
 165     int l2_size;
 166     int l1_size;
 167     int l1_vm_state_index;
 168     int csize_shift;
 169     int csize_mask;
 170     uint64_t cluster_offset_mask;
 171     uint64_t l1_table_offset;
 172     uint64_t *l1_table;
 173
 174     Qcow2Cache* l2_table_cache;
 175     Qcow2Cache* refcount_block_cache;
 176
 177     uint8_t *cluster_cache;
 178     uint8_t *cluster_data;
 179     uint64_t cluster_cache_offset;
 180     QLIST_HEAD(QCowClusterAlloc, QCowL2Meta) cluster_allocs;
 181
 182     uint64_t *refcount_table;
 183     uint64_t refcount_table_offset;
 184     uint32_t refcount_table_size;
 185     int64_t free_cluster_index;
 186     int64_t free_byte_offset;
 187
 188     CoMutex lock;
 189
 190     uint32_t crypt_method; /* current crypt method, 0 if no key yet */
 191     uint32_t crypt_method_header;
 192     AES_KEY aes_encrypt_key;
 193     AES_KEY aes_decrypt_key;
 194     uint64_t snapshots_offset;
 195     int snapshots_size;
 196     int nb_snapshots;
 197     QCowSnapshot *snapshots;
 198
 199     int flags;
 200     int qcow_version;
 201     bool use_lazy_refcounts;
 202     int refcount_order;
 203
 204     bool discard_passthrough[QCOW2_DISCARD_MAX];
 205
 206     uint64_t incompatible_features;
 207     uint64_t compatible_features;
 208     uint64_t autoclear_features;
 209
 210     size_t unknown_header_fields_size;
 211     void* unknown_header_fields;
 212     QLIST_HEAD(, Qcow2UnknownHeaderExtension) unknown_header_ext;
 213     QTAILQ_HEAD (, Qcow2DiscardRegion) discards;
 214     bool cache_discards;
 215 } BDRVQcowState;
 216
 217 /* XXX: use std qcow open function ? */
 218 typedef struct QCowCreateState {
 219     int cluster_size;
 220     int cluster_bits;
 221     uint16_t *refcount_block;
 222     uint64_t *refcount_table;
 223     int64_t l1_table_offset;
 224     int64_t refcount_table_offset;
 225     int64_t refcount_block_offset;
 226 } QCowCreateState;
 227
 228 struct QCowAIOCB;
 229
 230 typedef struct Qcow2COWRegion {
 231     /**
 232      * Offset of the COW region in bytes from the start of the first cluster
 233      * touched by the request.
 234      */
 235     uint64_t    offset;
 236
 237     /** Number of sectors to copy */
 238     int         nb_sectors;
 239 } Qcow2COWRegion;
 240
 241 /**
 242  * Describes an in-flight (part of a) write request that writes to clusters
 243  * that are not referenced in their L2 table yet.
 244  */
 245 typedef struct QCowL2Meta
 246 {
 247     /** Guest offset of the first newly allocated cluster */
 248     uint64_t offset;
 249
 250     /** Host offset of the first newly allocated cluster */
 251     uint64_t alloc_offset;
 252
 253     /**
 254      * Number of sectors from the start of the first allocated cluster to
 255      * the end of the (possibly shortened) request
 256      */
 257     int nb_available;
 258
 259     /** Number of newly allocated clusters */
 260     int nb_clusters;
 261
 262     /**
 263      * Requests that overlap with this allocation and wait to be restarted
 264      * when the allocating request has completed.
 265      */
 266     CoQueue dependent_requests;
 267
 268     /**
 269      * The COW Region between the start of the first allocated cluster and the
 270      * area the guest actually writes to.
 271      */
 272     Qcow2COWRegion cow_start;
 273
 274     /**
 275      * The COW Region between the area the guest actually writes to and the
 276      * end of the last allocated cluster.
 277      */
 278     Qcow2COWRegion cow_end;
 279
 280     /** Pointer to next L2Meta of the same write request */
 281     struct QCowL2Meta *next;
 282
 283     QLIST_ENTRY(QCowL2Meta) next_in_flight;
 284 } QCowL2Meta;
 285
 286 enum {
 287     QCOW2_CLUSTER_UNALLOCATED,
 288     QCOW2_CLUSTER_NORMAL,
 289     QCOW2_CLUSTER_COMPRESSED,
 290     QCOW2_CLUSTER_ZERO
 291 };
 292
 293 typedef enum QCow2MetadataOverlap {
 294     QCOW2_OL_MAIN_HEADER_BITNR    = 0,
 295     QCOW2_OL_ACTIVE_L1_BITNR      = 1,
 296     QCOW2_OL_ACTIVE_L2_BITNR      = 2,
 297     QCOW2_OL_REFCOUNT_TABLE_BITNR = 3,
 298     QCOW2_OL_REFCOUNT_BLOCK_BITNR = 4,
 299     QCOW2_OL_SNAPSHOT_TABLE_BITNR = 5,
 300     QCOW2_OL_INACTIVE_L1_BITNR    = 6,
 301     QCOW2_OL_INACTIVE_L2_BITNR    = 7,
 302
 303     QCOW2_OL_MAX_BITNR            = 8,
 304
 305     QCOW2_OL_NONE           = 0,
 306     QCOW2_OL_MAIN_HEADER    = (1 << QCOW2_OL_MAIN_HEADER_BITNR),
 307     QCOW2_OL_ACTIVE_L1      = (1 << QCOW2_OL_ACTIVE_L1_BITNR),
 308     QCOW2_OL_ACTIVE_L2      = (1 << QCOW2_OL_ACTIVE_L2_BITNR),
 309     QCOW2_OL_REFCOUNT_TABLE = (1 << QCOW2_OL_REFCOUNT_TABLE_BITNR),
 310     QCOW2_OL_REFCOUNT_BLOCK = (1 << QCOW2_OL_REFCOUNT_BLOCK_BITNR),
 311     QCOW2_OL_SNAPSHOT_TABLE = (1 << QCOW2_OL_SNAPSHOT_TABLE_BITNR),
 312     QCOW2_OL_INACTIVE_L1    = (1 << QCOW2_OL_INACTIVE_L1_BITNR),
 313     /* NOTE: Checking overlaps with inactive L2 tables will result in bdrv
 314      * reads. */
 315     QCOW2_OL_INACTIVE_L2    = (1 << QCOW2_OL_INACTIVE_L2_BITNR),
 316 } QCow2MetadataOverlap;
 317
 318 /* Perform all overlap checks which don't require disk access */
 319 #define QCOW2_OL_CACHED \
 320     (QCOW2_OL_MAIN_HEADER | QCOW2_OL_ACTIVE_L1 | QCOW2_OL_ACTIVE_L2 | \
 321      QCOW2_OL_REFCOUNT_TABLE | QCOW2_OL_REFCOUNT_BLOCK | \
 322      QCOW2_OL_SNAPSHOT_TABLE | QCOW2_OL_INACTIVE_L1)
 323
 324 /* The default checks to perform */
 325 #define QCOW2_OL_DEFAULT QCOW2_OL_CACHED
 326
 327 #define L1E_OFFSET_MASK 0x00ffffffffffff00ULL
 328 #define L2E_OFFSET_MASK 0x00ffffffffffff00ULL
 329 #define L2E_COMPRESSED_OFFSET_SIZE_MASK 0x3fffffffffffffffULL
 330
 331 #define REFT_OFFSET_MASK 0xffffffffffffff00ULL
 332
 333 static inline int64_t start_of_cluster(BDRVQcowState *s, int64_t offset)
 334 {
 335     return offset & ~(s->cluster_size - 1);
 336 }
 337
 338 static inline int64_t offset_into_cluster(BDRVQcowState *s, int64_t offset)
 339 {
 340     return offset & (s->cluster_size - 1);
 341 }
 342
 343 static inline int size_to_clusters(BDRVQcowState *s, int64_t size)
 344 {
 345     return (size + (s->cluster_size - 1)) >> s->cluster_bits;
 346 }
 347
 348 static inline int64_t size_to_l1(BDRVQcowState *s, int64_t size)
 349 {
 350     int shift = s->cluster_bits + s->l2_bits;
 351     return (size + (1ULL << shift) - 1) >> shift;
 352 }
 353
 354 static inline int offset_to_l2_index(BDRVQcowState *s, int64_t offset)
 355 {
 356     return (offset >> s->cluster_bits) & (s->l2_size - 1);
 357 }
 358
 359 static inline int64_t align_offset(int64_t offset, int n)
 360 {
 361     offset = (offset + n - 1) & ~(n - 1);
 362     return offset;
 363 }
 364
 365 static inline int64_t qcow2_vm_state_offset(BDRVQcowState *s)
 366 {
 367     return (int64_t)s->l1_vm_state_index << (s->cluster_bits + s->l2_bits);
 368 }
 369
 370 static inline int qcow2_get_cluster_type(uint64_t l2_entry)
 371 {
 372     if (l2_entry & QCOW_OFLAG_COMPRESSED) {
 373         return QCOW2_CLUSTER_COMPRESSED;
 374     } else if (l2_entry & QCOW_OFLAG_ZERO) {
 375         return QCOW2_CLUSTER_ZERO;
 376     } else if (!(l2_entry & L2E_OFFSET_MASK)) {
 377         return QCOW2_CLUSTER_UNALLOCATED;
 378     } else {
 379         return QCOW2_CLUSTER_NORMAL;
 380     }
 381 }
 382
 383 /* Check whether refcounts are eager or lazy */
 384 static inline bool qcow2_need_accurate_refcounts(BDRVQcowState *s)
 385 {
 386     return !(s->incompatible_features & QCOW2_INCOMPAT_DIRTY);
 387 }
 388
 389 static inline uint64_t l2meta_cow_start(QCowL2Meta *m)
 390 {
 391     return m->offset + m->cow_start.offset;
 392 }
 393
 394 static inline uint64_t l2meta_cow_end(QCowL2Meta *m)
 395 {
 396     return m->offset + m->cow_end.offset
 397         + (m->cow_end.nb_sectors << BDRV_SECTOR_BITS);
 398 }
 399
 400 // FIXME Need qcow2_ prefix to global functions
 401
 402 /* qcow2.c functions */
 403 int qcow2_backing_read1(BlockDriverState *bs, QEMUIOVector *qiov,
 404                   int64_t sector_num, int nb_sectors);
 405
 406 int qcow2_mark_dirty(BlockDriverState *bs);
 407 int qcow2_mark_corrupt(BlockDriverState *bs);
 408 int qcow2_mark_consistent(BlockDriverState *bs);
 409 int qcow2_update_header(BlockDriverState *bs);
 410
 411 /* qcow2-refcount.c functions */
 412 int qcow2_refcount_init(BlockDriverState *bs);
 413 void qcow2_refcount_close(BlockDriverState *bs);
 414
 415 int qcow2_update_cluster_refcount(BlockDriverState *bs, int64_t cluster_index,
 416                                   int addend, enum qcow2_discard_type type);
 417
 418 int64_t qcow2_alloc_clusters(BlockDriverState *bs, int64_t size);
 419 int qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t offset,
 420     int nb_clusters);
 421 int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size);
 422 void qcow2_free_clusters(BlockDriverState *bs,
 423                           int64_t offset, int64_t size,
 424                           enum qcow2_discard_type type);
 425 void qcow2_free_any_clusters(BlockDriverState *bs, uint64_t l2_entry,
 426                              int nb_clusters, enum qcow2_discard_type type);
 427
 428 int qcow2_update_snapshot_refcount(BlockDriverState *bs,
 429     int64_t l1_table_offset, int l1_size, int addend);
 430
 431 int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
 432                           BdrvCheckMode fix);
 433
 434 void qcow2_process_discards(BlockDriverState *bs, int ret);
 435
 436 int qcow2_check_metadata_overlap(BlockDriverState *bs, int chk, int64_t offset,
 437                                  int64_t size);
 438 int qcow2_pre_write_overlap_check(BlockDriverState *bs, int chk, int64_t offset,
 439                                   int64_t size);
 440
 441 /* qcow2-cluster.c functions */
 442 int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size,
 443                         bool exact_size);
 444 int qcow2_write_l1_entry(BlockDriverState *bs, int l1_index);
 445 void qcow2_l2_cache_reset(BlockDriverState *bs);
 446 int qcow2_decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset);
 447 void qcow2_encrypt_sectors(BDRVQcowState *s, int64_t sector_num,
 448                      uint8_t *out_buf, const uint8_t *in_buf,
 449                      int nb_sectors, int enc,
 450                      const AES_KEY *key);
 451
 452 int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset,
 453     int *num, uint64_t *cluster_offset);
 454 int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset,
 455     int n_start, int n_end, int *num, uint64_t *host_offset, QCowL2Meta **m);
 456 uint64_t qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs,
 457                                          uint64_t offset,
 458                                          int compressed_size);
 459
 460 int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m);
 461 int qcow2_discard_clusters(BlockDriverState *bs, uint64_t offset,
 462     int nb_sectors, enum qcow2_discard_type type);
 463 int qcow2_zero_clusters(BlockDriverState *bs, uint64_t offset, int nb_sectors);
 464
 465 int qcow2_expand_zero_clusters(BlockDriverState *bs);
 466
 467 /* qcow2-snapshot.c functions */
 468 int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info);
 469 int qcow2_snapshot_goto(BlockDriverState *bs, const char *snapshot_id);
 470 int qcow2_snapshot_delete(BlockDriverState *bs,
 471                           const char *snapshot_id,
 472                           const char *name,
 473                           Error **errp);
 474 int qcow2_snapshot_list(BlockDriverState *bs, QEMUSnapshotInfo **psn_tab);
 475 int qcow2_snapshot_load_tmp(BlockDriverState *bs, const char *snapshot_name);
 476
 477 void qcow2_free_snapshots(BlockDriverState *bs);
 478 int qcow2_read_snapshots(BlockDriverState *bs);
 479
 480 /* qcow2-cache.c functions */
 481 Qcow2Cache *qcow2_cache_create(BlockDriverState *bs, int num_tables);
 482 int qcow2_cache_destroy(BlockDriverState* bs, Qcow2Cache *c);
 483
 484 void qcow2_cache_entry_mark_dirty(Qcow2Cache *c, void *table);
 485 int qcow2_cache_flush(BlockDriverState *bs, Qcow2Cache *c);
 486 int qcow2_cache_set_dependency(BlockDriverState *bs, Qcow2Cache *c,
 487     Qcow2Cache *dependency);
 488 void qcow2_cache_depends_on_flush(Qcow2Cache *c);
 489
 490 int qcow2_cache_empty(BlockDriverState *bs, Qcow2Cache *c);
 491
 492 int qcow2_cache_get(BlockDriverState *bs, Qcow2Cache *c, uint64_t offset,
 493     void **table);
 494 int qcow2_cache_get_empty(BlockDriverState *bs, Qcow2Cache *c, uint64_t offset,
 495     void **table);
 496 int qcow2_cache_put(BlockDriverState *bs, Qcow2Cache *c, void **table);
 497
 498 #endif