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     (1LL << 63)
  44 /* indicate that the cluster is compressed (they never have the copied flag) */
  45 #define QCOW_OFLAG_COMPRESSED (1LL << 62)
  46 /* The cluster reads as all zeros */
  47 #define QCOW_OFLAG_ZERO (1LL << 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
  64 typedef struct QCowHeader {
  65     uint32_t magic;
  66     uint32_t version;
  67     uint64_t backing_file_offset;
  68     uint32_t backing_file_size;
  69     uint32_t cluster_bits;
  70     uint64_t size; /* in bytes */
  71     uint32_t crypt_method;
  72     uint32_t l1_size; /* XXX: save number of clusters instead ? */
  73     uint64_t l1_table_offset;
  74     uint64_t refcount_table_offset;
  75     uint32_t refcount_table_clusters;
  76     uint32_t nb_snapshots;
  77     uint64_t snapshots_offset;
  78
  79     /* The following fields are only valid for version >= 3 */
  80     uint64_t incompatible_features;
  81     uint64_t compatible_features;
  82     uint64_t autoclear_features;
  83
  84     uint32_t refcount_order;
  85     uint32_t header_length;
  86 } QCowHeader;
  87
  88 typedef struct QCowSnapshot {
  89     uint64_t l1_table_offset;
  90     uint32_t l1_size;
  91     char *id_str;
  92     char *name;
  93     uint64_t disk_size;
  94     uint64_t vm_state_size;
  95     uint32_t date_sec;
  96     uint32_t date_nsec;
  97     uint64_t vm_clock_nsec;
  98 } QCowSnapshot;
  99
 100 struct Qcow2Cache;
 101 typedef struct Qcow2Cache Qcow2Cache;
 102
 103 typedef struct Qcow2UnknownHeaderExtension {
 104     uint32_t magic;
 105     uint32_t len;
 106     QLIST_ENTRY(Qcow2UnknownHeaderExtension) next;
 107     uint8_t data[];
 108 } Qcow2UnknownHeaderExtension;
 109
 110 enum {
 111     QCOW2_FEAT_TYPE_INCOMPATIBLE    = 0,
 112     QCOW2_FEAT_TYPE_COMPATIBLE      = 1,
 113     QCOW2_FEAT_TYPE_AUTOCLEAR       = 2,
 114 };
 115
 116 /* Incompatible feature bits */
 117 enum {
 118     QCOW2_INCOMPAT_DIRTY_BITNR   = 0,
 119     QCOW2_INCOMPAT_DIRTY         = 1 << QCOW2_INCOMPAT_DIRTY_BITNR,
 120
 121     QCOW2_INCOMPAT_MASK          = QCOW2_INCOMPAT_DIRTY,
 122 };
 123
 124 /* Compatible feature bits */
 125 enum {
 126     QCOW2_COMPAT_LAZY_REFCOUNTS_BITNR = 0,
 127     QCOW2_COMPAT_LAZY_REFCOUNTS       = 1 << QCOW2_COMPAT_LAZY_REFCOUNTS_BITNR,
 128
 129     QCOW2_COMPAT_FEAT_MASK            = QCOW2_COMPAT_LAZY_REFCOUNTS,
 130 };
 131
 132 typedef struct Qcow2Feature {
 133     uint8_t type;
 134     uint8_t bit;
 135     char    name[46];
 136 } QEMU_PACKED Qcow2Feature;
 137
 138 typedef struct BDRVQcowState {
 139     int cluster_bits;
 140     int cluster_size;
 141     int cluster_sectors;
 142     int l2_bits;
 143     int l2_size;
 144     int l1_size;
 145     int l1_vm_state_index;
 146     int csize_shift;
 147     int csize_mask;
 148     uint64_t cluster_offset_mask;
 149     uint64_t l1_table_offset;
 150     uint64_t *l1_table;
 151
 152     Qcow2Cache* l2_table_cache;
 153     Qcow2Cache* refcount_block_cache;
 154
 155     uint8_t *cluster_cache;
 156     uint8_t *cluster_data;
 157     uint64_t cluster_cache_offset;
 158     QLIST_HEAD(QCowClusterAlloc, QCowL2Meta) cluster_allocs;
 159
 160     uint64_t *refcount_table;
 161     uint64_t refcount_table_offset;
 162     uint32_t refcount_table_size;
 163     int64_t free_cluster_index;
 164     int64_t free_byte_offset;
 165
 166     CoMutex lock;
 167
 168     uint32_t crypt_method; /* current crypt method, 0 if no key yet */
 169     uint32_t crypt_method_header;
 170     AES_KEY aes_encrypt_key;
 171     AES_KEY aes_decrypt_key;
 172     uint64_t snapshots_offset;
 173     int snapshots_size;
 174     int nb_snapshots;
 175     QCowSnapshot *snapshots;
 176
 177     int flags;
 178     int qcow_version;
 179     bool use_lazy_refcounts;
 180
 181     uint64_t incompatible_features;
 182     uint64_t compatible_features;
 183     uint64_t autoclear_features;
 184
 185     size_t unknown_header_fields_size;
 186     void* unknown_header_fields;
 187     QLIST_HEAD(, Qcow2UnknownHeaderExtension) unknown_header_ext;
 188 } BDRVQcowState;
 189
 190 /* XXX: use std qcow open function ? */
 191 typedef struct QCowCreateState {
 192     int cluster_size;
 193     int cluster_bits;
 194     uint16_t *refcount_block;
 195     uint64_t *refcount_table;
 196     int64_t l1_table_offset;
 197     int64_t refcount_table_offset;
 198     int64_t refcount_block_offset;
 199 } QCowCreateState;
 200
 201 struct QCowAIOCB;
 202
 203 typedef struct Qcow2COWRegion {
 204     /**
 205      * Offset of the COW region in bytes from the start of the first cluster
 206      * touched by the request.
 207      */
 208     uint64_t    offset;
 209
 210     /** Number of sectors to copy */
 211     int         nb_sectors;
 212 } Qcow2COWRegion;
 213
 214 /**
 215  * Describes an in-flight (part of a) write request that writes to clusters
 216  * that are not referenced in their L2 table yet.
 217  */
 218 typedef struct QCowL2Meta
 219 {
 220     /** Guest offset of the first newly allocated cluster */
 221     uint64_t offset;
 222
 223     /** Host offset of the first newly allocated cluster */
 224     uint64_t alloc_offset;
 225
 226     /**
 227      * Number of sectors from the start of the first allocated cluster to
 228      * the end of the (possibly shortened) request
 229      */
 230     int nb_available;
 231
 232     /** Number of newly allocated clusters */
 233     int nb_clusters;
 234
 235     /**
 236      * Requests that overlap with this allocation and wait to be restarted
 237      * when the allocating request has completed.
 238      */
 239     CoQueue dependent_requests;
 240
 241     /**
 242      * The COW Region between the start of the first allocated cluster and the
 243      * area the guest actually writes to.
 244      */
 245     Qcow2COWRegion cow_start;
 246
 247     /**
 248      * The COW Region between the area the guest actually writes to and the
 249      * end of the last allocated cluster.
 250      */
 251     Qcow2COWRegion cow_end;
 252
 253     /** Pointer to next L2Meta of the same write request */
 254     struct QCowL2Meta *next;
 255
 256     QLIST_ENTRY(QCowL2Meta) next_in_flight;
 257 } QCowL2Meta;
 258
 259 enum {
 260     QCOW2_CLUSTER_UNALLOCATED,
 261     QCOW2_CLUSTER_NORMAL,
 262     QCOW2_CLUSTER_COMPRESSED,
 263     QCOW2_CLUSTER_ZERO
 264 };
 265
 266 #define L1E_OFFSET_MASK 0x00ffffffffffff00ULL
 267 #define L2E_OFFSET_MASK 0x00ffffffffffff00ULL
 268 #define L2E_COMPRESSED_OFFSET_SIZE_MASK 0x3fffffffffffffffULL
 269
 270 #define REFT_OFFSET_MASK 0xffffffffffffff00ULL
 271
 272 static inline int64_t start_of_cluster(BDRVQcowState *s, int64_t offset)
 273 {
 274     return offset & ~(s->cluster_size - 1);
 275 }
 276
 277 static inline int64_t offset_into_cluster(BDRVQcowState *s, int64_t offset)
 278 {
 279     return offset & (s->cluster_size - 1);
 280 }
 281
 282 static inline int size_to_clusters(BDRVQcowState *s, int64_t size)
 283 {
 284     return (size + (s->cluster_size - 1)) >> s->cluster_bits;
 285 }
 286
 287 static inline int size_to_l1(BDRVQcowState *s, int64_t size)
 288 {
 289     int shift = s->cluster_bits + s->l2_bits;
 290     return (size + (1ULL << shift) - 1) >> shift;
 291 }
 292
 293 static inline int offset_to_l2_index(BDRVQcowState *s, int64_t offset)
 294 {
 295     return (offset >> s->cluster_bits) & (s->l2_size - 1);
 296 }
 297
 298 static inline int64_t align_offset(int64_t offset, int n)
 299 {
 300     offset = (offset + n - 1) & ~(n - 1);
 301     return offset;
 302 }
 303
 304 static inline int qcow2_get_cluster_type(uint64_t l2_entry)
 305 {
 306     if (l2_entry & QCOW_OFLAG_COMPRESSED) {
 307         return QCOW2_CLUSTER_COMPRESSED;
 308     } else if (l2_entry & QCOW_OFLAG_ZERO) {
 309         return QCOW2_CLUSTER_ZERO;
 310     } else if (!(l2_entry & L2E_OFFSET_MASK)) {
 311         return QCOW2_CLUSTER_UNALLOCATED;
 312     } else {
 313         return QCOW2_CLUSTER_NORMAL;
 314     }
 315 }
 316
 317 /* Check whether refcounts are eager or lazy */
 318 static inline bool qcow2_need_accurate_refcounts(BDRVQcowState *s)
 319 {
 320     return !(s->incompatible_features & QCOW2_INCOMPAT_DIRTY);
 321 }
 322
 323 static inline uint64_t l2meta_cow_start(QCowL2Meta *m)
 324 {
 325     return m->offset + m->cow_start.offset;
 326 }
 327
 328 static inline uint64_t l2meta_cow_end(QCowL2Meta *m)
 329 {
 330     return m->offset + m->cow_end.offset
 331         + (m->cow_end.nb_sectors << BDRV_SECTOR_BITS);
 332 }
 333
 334 // FIXME Need qcow2_ prefix to global functions
 335
 336 /* qcow2.c functions */
 337 int qcow2_backing_read1(BlockDriverState *bs, QEMUIOVector *qiov,
 338                   int64_t sector_num, int nb_sectors);
 339
 340 int qcow2_mark_dirty(BlockDriverState *bs);
 341 int qcow2_update_header(BlockDriverState *bs);
 342
 343 /* qcow2-refcount.c functions */
 344 int qcow2_refcount_init(BlockDriverState *bs);
 345 void qcow2_refcount_close(BlockDriverState *bs);
 346
 347 int64_t qcow2_alloc_clusters(BlockDriverState *bs, int64_t size);
 348 int qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t offset,
 349     int nb_clusters);
 350 int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size);
 351 void qcow2_free_clusters(BlockDriverState *bs,
 352     int64_t offset, int64_t size);
 353 void qcow2_free_any_clusters(BlockDriverState *bs,
 354     uint64_t cluster_offset, int nb_clusters);
 355
 356 int qcow2_update_snapshot_refcount(BlockDriverState *bs,
 357     int64_t l1_table_offset, int l1_size, int addend);
 358
 359 int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
 360                           BdrvCheckMode fix);
 361
 362 /* qcow2-cluster.c functions */
 363 int qcow2_grow_l1_table(BlockDriverState *bs, int min_size, bool exact_size);
 364 void qcow2_l2_cache_reset(BlockDriverState *bs);
 365 int qcow2_decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset);
 366 void qcow2_encrypt_sectors(BDRVQcowState *s, int64_t sector_num,
 367                      uint8_t *out_buf, const uint8_t *in_buf,
 368                      int nb_sectors, int enc,
 369                      const AES_KEY *key);
 370
 371 int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset,
 372     int *num, uint64_t *cluster_offset);
 373 int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset,
 374     int n_start, int n_end, int *num, uint64_t *host_offset, QCowL2Meta **m);
 375 uint64_t qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs,
 376                                          uint64_t offset,
 377                                          int compressed_size);
 378
 379 int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m);
 380 int qcow2_discard_clusters(BlockDriverState *bs, uint64_t offset,
 381     int nb_sectors);
 382 int qcow2_zero_clusters(BlockDriverState *bs, uint64_t offset, int nb_sectors);
 383
 384 /* qcow2-snapshot.c functions */
 385 int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info);
 386 int qcow2_snapshot_goto(BlockDriverState *bs, const char *snapshot_id);
 387 int qcow2_snapshot_delete(BlockDriverState *bs, const char *snapshot_id);
 388 int qcow2_snapshot_list(BlockDriverState *bs, QEMUSnapshotInfo **psn_tab);
 389 int qcow2_snapshot_load_tmp(BlockDriverState *bs, const char *snapshot_name);
 390
 391 void qcow2_free_snapshots(BlockDriverState *bs);
 392 int qcow2_read_snapshots(BlockDriverState *bs);
 393
 394 /* qcow2-cache.c functions */
 395 Qcow2Cache *qcow2_cache_create(BlockDriverState *bs, int num_tables);
 396 int qcow2_cache_destroy(BlockDriverState* bs, Qcow2Cache *c);
 397
 398 void qcow2_cache_entry_mark_dirty(Qcow2Cache *c, void *table);
 399 int qcow2_cache_flush(BlockDriverState *bs, Qcow2Cache *c);
 400 int qcow2_cache_set_dependency(BlockDriverState *bs, Qcow2Cache *c,
 401     Qcow2Cache *dependency);
 402 void qcow2_cache_depends_on_flush(Qcow2Cache *c);
 403
 404 int qcow2_cache_get(BlockDriverState *bs, Qcow2Cache *c, uint64_t offset,
 405     void **table);
 406 int qcow2_cache_get_empty(BlockDriverState *bs, Qcow2Cache *c, uint64_t offset,
 407     void **table);
 408 int qcow2_cache_put(BlockDriverState *bs, Qcow2Cache *c, void **table);
 409
 410 #endif