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