block/qcow.c

   1 /*
   2  * Block driver for the QCOW 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 #include "qemu-common.h"
  25 #include "block/block_int.h"
  26 #include "qemu/module.h"
  27 #include <zlib.h>
  28 #include "qapi/qmp/qerror.h"
  29 #include "crypto/cipher.h"
  30 #include "migration/migration.h"
  31
  32 /**************************************************************/
  33 /* QEMU COW block driver with compression and encryption support */
  34
  35 #define QCOW_MAGIC (('Q' << 24) | ('F' << 16) | ('I' << 8) | 0xfb)
  36 #define QCOW_VERSION 1
  37
  38 #define QCOW_CRYPT_NONE 0
  39 #define QCOW_CRYPT_AES  1
  40
  41 #define QCOW_OFLAG_COMPRESSED (1LL << 63)
  42
  43 typedef struct QCowHeader {
  44     uint32_t magic;
  45     uint32_t version;
  46     uint64_t backing_file_offset;
  47     uint32_t backing_file_size;
  48     uint32_t mtime;
  49     uint64_t size; /* in bytes */
  50     uint8_t cluster_bits;
  51     uint8_t l2_bits;
  52     uint16_t padding;
  53     uint32_t crypt_method;
  54     uint64_t l1_table_offset;
  55 } QEMU_PACKED QCowHeader;
  56
  57 #define L2_CACHE_SIZE 16
  58
  59 typedef struct BDRVQcowState {
  60     int cluster_bits;
  61     int cluster_size;
  62     int cluster_sectors;
  63     int l2_bits;
  64     int l2_size;
  65     unsigned int l1_size;
  66     uint64_t cluster_offset_mask;
  67     uint64_t l1_table_offset;
  68     uint64_t *l1_table;
  69     uint64_t *l2_cache;
  70     uint64_t l2_cache_offsets[L2_CACHE_SIZE];
  71     uint32_t l2_cache_counts[L2_CACHE_SIZE];
  72     uint8_t *cluster_cache;
  73     uint8_t *cluster_data;
  74     uint64_t cluster_cache_offset;
  75     QCryptoCipher *cipher; /* NULL if no key yet */
  76     uint32_t crypt_method_header;
  77     CoMutex lock;
  78     Error *migration_blocker;
  79 } BDRVQcowState;
  80
  81 static int decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset);
  82
  83 static int qcow_probe(const uint8_t *buf, int buf_size, const char *filename)
  84 {
  85     const QCowHeader *cow_header = (const void *)buf;
  86
  87     if (buf_size >= sizeof(QCowHeader) &&
  88         be32_to_cpu(cow_header->magic) == QCOW_MAGIC &&
  89         be32_to_cpu(cow_header->version) == QCOW_VERSION)
  90         return 100;
  91     else
  92         return 0;
  93 }
  94
  95 static int qcow_open(BlockDriverState *bs, QDict *options, int flags,
  96                      Error **errp)
  97 {
  98     BDRVQcowState *s = bs->opaque;
  99     unsigned int len, i, shift;
 100     int ret;
 101     QCowHeader header;
 102
 103     ret = bdrv_pread(bs->file, 0, &header, sizeof(header));
 104     if (ret < 0) {
 105         goto fail;
 106     }
 107     be32_to_cpus(&header.magic);
 108     be32_to_cpus(&header.version);
 109     be64_to_cpus(&header.backing_file_offset);
 110     be32_to_cpus(&header.backing_file_size);
 111     be32_to_cpus(&header.mtime);
 112     be64_to_cpus(&header.size);
 113     be32_to_cpus(&header.crypt_method);
 114     be64_to_cpus(&header.l1_table_offset);
 115
 116     if (header.magic != QCOW_MAGIC) {
 117         error_setg(errp, "Image not in qcow format");
 118         ret = -EINVAL;
 119         goto fail;
 120     }
 121     if (header.version != QCOW_VERSION) {
 122         char version[64];
 123         snprintf(version, sizeof(version), "QCOW version %" PRIu32,
 124                  header.version);
 125         error_setg(errp, QERR_UNKNOWN_BLOCK_FORMAT_FEATURE,
 126                    bdrv_get_device_or_node_name(bs), "qcow", version);
 127         ret = -ENOTSUP;
 128         goto fail;
 129     }
 130
 131     if (header.size <= 1) {
 132         error_setg(errp, "Image size is too small (must be at least 2 bytes)");
 133         ret = -EINVAL;
 134         goto fail;
 135     }
 136     if (header.cluster_bits < 9 || header.cluster_bits > 16) {
 137         error_setg(errp, "Cluster size must be between 512 and 64k");
 138         ret = -EINVAL;
 139         goto fail;
 140     }
 141
 142     /* l2_bits specifies number of entries; storing a uint64_t in each entry,
 143      * so bytes = num_entries << 3. */
 144     if (header.l2_bits < 9 - 3 || header.l2_bits > 16 - 3) {
 145         error_setg(errp, "L2 table size must be between 512 and 64k");
 146         ret = -EINVAL;
 147         goto fail;
 148     }
 149
 150     if (header.crypt_method > QCOW_CRYPT_AES) {
 151         error_setg(errp, "invalid encryption method in qcow header");
 152         ret = -EINVAL;
 153         goto fail;
 154     }
 155     if (!qcrypto_cipher_supports(QCRYPTO_CIPHER_ALG_AES_128)) {
 156         error_setg(errp, "AES cipher not available");
 157         ret = -EINVAL;
 158         goto fail;
 159     }
 160     s->crypt_method_header = header.crypt_method;
 161     if (s->crypt_method_header) {
 162         bs->encrypted = 1;
 163     }
 164     s->cluster_bits = header.cluster_bits;
 165     s->cluster_size = 1 << s->cluster_bits;
 166     s->cluster_sectors = 1 << (s->cluster_bits - 9);
 167     s->l2_bits = header.l2_bits;
 168     s->l2_size = 1 << s->l2_bits;
 169     bs->total_sectors = header.size / 512;
 170     s->cluster_offset_mask = (1LL << (63 - s->cluster_bits)) - 1;
 171
 172     /* read the level 1 table */
 173     shift = s->cluster_bits + s->l2_bits;
 174     if (header.size > UINT64_MAX - (1LL << shift)) {
 175         error_setg(errp, "Image too large");
 176         ret = -EINVAL;
 177         goto fail;
 178     } else {
 179         uint64_t l1_size = (header.size + (1LL << shift) - 1) >> shift;
 180         if (l1_size > INT_MAX / sizeof(uint64_t)) {
 181             error_setg(errp, "Image too large");
 182             ret = -EINVAL;
 183             goto fail;
 184         }
 185         s->l1_size = l1_size;
 186     }
 187
 188     s->l1_table_offset = header.l1_table_offset;
 189     s->l1_table = g_try_new(uint64_t, s->l1_size);
 190     if (s->l1_table == NULL) {
 191         error_setg(errp, "Could not allocate memory for L1 table");
 192         ret = -ENOMEM;
 193         goto fail;
 194     }
 195
 196     ret = bdrv_pread(bs->file, s->l1_table_offset, s->l1_table,
 197                s->l1_size * sizeof(uint64_t));
 198     if (ret < 0) {
 199         goto fail;
 200     }
 201
 202     for(i = 0;i < s->l1_size; i++) {
 203         be64_to_cpus(&s->l1_table[i]);
 204     }
 205
 206     /* alloc L2 cache (max. 64k * 16 * 8 = 8 MB) */
 207     s->l2_cache =
 208         qemu_try_blockalign(bs->file,
 209                             s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t));
 210     if (s->l2_cache == NULL) {
 211         error_setg(errp, "Could not allocate L2 table cache");
 212         ret = -ENOMEM;
 213         goto fail;
 214     }
 215     s->cluster_cache = g_malloc(s->cluster_size);
 216     s->cluster_data = g_malloc(s->cluster_size);
 217     s->cluster_cache_offset = -1;
 218
 219     /* read the backing file name */
 220     if (header.backing_file_offset != 0) {
 221         len = header.backing_file_size;
 222         if (len > 1023 || len >= sizeof(bs->backing_file)) {
 223             error_setg(errp, "Backing file name too long");
 224             ret = -EINVAL;
 225             goto fail;
 226         }
 227         ret = bdrv_pread(bs->file, header.backing_file_offset,
 228                    bs->backing_file, len);
 229         if (ret < 0) {
 230             goto fail;
 231         }
 232         bs->backing_file[len] = '\0';
 233     }
 234
 235     /* Disable migration when qcow images are used */
 236     error_setg(&s->migration_blocker, "The qcow format used by node '%s' "
 237                "does not support live migration",
 238                bdrv_get_device_or_node_name(bs));
 239     migrate_add_blocker(s->migration_blocker);
 240
 241     qemu_co_mutex_init(&s->lock);
 242     return 0;
 243
 244  fail:
 245     g_free(s->l1_table);
 246     qemu_vfree(s->l2_cache);
 247     g_free(s->cluster_cache);
 248     g_free(s->cluster_data);
 249     return ret;
 250 }
 251
 252
 253 /* We have nothing to do for QCOW reopen, stubs just return
 254  * success */
 255 static int qcow_reopen_prepare(BDRVReopenState *state,
 256                                BlockReopenQueue *queue, Error **errp)
 257 {
 258     return 0;
 259 }
 260
 261 static int qcow_set_key(BlockDriverState *bs, const char *key)
 262 {
 263     BDRVQcowState *s = bs->opaque;
 264     uint8_t keybuf[16];
 265     int len, i;
 266     Error *err;
 267
 268     memset(keybuf, 0, 16);
 269     len = strlen(key);
 270     if (len > 16)
 271         len = 16;
 272     /* XXX: we could compress the chars to 7 bits to increase
 273        entropy */
 274     for(i = 0;i < len;i++) {
 275         keybuf[i] = key[i];
 276     }
 277     assert(bs->encrypted);
 278
 279     qcrypto_cipher_free(s->cipher);
 280     s->cipher = qcrypto_cipher_new(
 281         QCRYPTO_CIPHER_ALG_AES_128,
 282         QCRYPTO_CIPHER_MODE_CBC,
 283         keybuf, G_N_ELEMENTS(keybuf),
 284         &err);
 285
 286     if (!s->cipher) {
 287         /* XXX would be nice if errors in this method could
 288          * be properly propagate to the caller. Would need
 289          * the bdrv_set_key() API signature to be fixed. */
 290         error_free(err);
 291         return -1;
 292     }
 293     return 0;
 294 }
 295
 296 /* The crypt function is compatible with the linux cryptoloop
 297    algorithm for < 4 GB images. NOTE: out_buf == in_buf is
 298    supported */
 299 static int encrypt_sectors(BDRVQcowState *s, int64_t sector_num,
 300                            uint8_t *out_buf, const uint8_t *in_buf,
 301                            int nb_sectors, bool enc, Error **errp)
 302 {
 303     union {
 304         uint64_t ll[2];
 305         uint8_t b[16];
 306     } ivec;
 307     int i;
 308     int ret;
 309
 310     for(i = 0; i < nb_sectors; i++) {
 311         ivec.ll[0] = cpu_to_le64(sector_num);
 312         ivec.ll[1] = 0;
 313         if (qcrypto_cipher_setiv(s->cipher,
 314                                  ivec.b, G_N_ELEMENTS(ivec.b),
 315                                  errp) < 0) {
 316             return -1;
 317         }
 318         if (enc) {
 319             ret = qcrypto_cipher_encrypt(s->cipher,
 320                                          in_buf,
 321                                          out_buf,
 322                                          512,
 323                                          errp);
 324         } else {
 325             ret = qcrypto_cipher_decrypt(s->cipher,
 326                                          in_buf,
 327                                          out_buf,
 328                                          512,
 329                                          errp);
 330         }
 331         if (ret < 0) {
 332             return -1;
 333         }
 334         sector_num++;
 335         in_buf += 512;
 336         out_buf += 512;
 337     }
 338     return 0;
 339 }
 340
 341 /* 'allocate' is:
 342  *
 343  * 0 to not allocate.
 344  *
 345  * 1 to allocate a normal cluster (for sector indexes 'n_start' to
 346  * 'n_end')
 347  *
 348  * 2 to allocate a compressed cluster of size
 349  * 'compressed_size'. 'compressed_size' must be > 0 and <
 350  * cluster_size
 351  *
 352  * return 0 if not allocated.
 353  */
 354 static uint64_t get_cluster_offset(BlockDriverState *bs,
 355                                    uint64_t offset, int allocate,
 356                                    int compressed_size,
 357                                    int n_start, int n_end)
 358 {
 359     BDRVQcowState *s = bs->opaque;
 360     int min_index, i, j, l1_index, l2_index;
 361     uint64_t l2_offset, *l2_table, cluster_offset, tmp;
 362     uint32_t min_count;
 363     int new_l2_table;
 364
 365     l1_index = offset >> (s->l2_bits + s->cluster_bits);
 366     l2_offset = s->l1_table[l1_index];
 367     new_l2_table = 0;
 368     if (!l2_offset) {
 369         if (!allocate)
 370             return 0;
 371         /* allocate a new l2 entry */
 372         l2_offset = bdrv_getlength(bs->file);
 373         /* round to cluster size */
 374         l2_offset = (l2_offset + s->cluster_size - 1) & ~(s->cluster_size - 1);
 375         /* update the L1 entry */
 376         s->l1_table[l1_index] = l2_offset;
 377         tmp = cpu_to_be64(l2_offset);
 378         if (bdrv_pwrite_sync(bs->file,
 379                 s->l1_table_offset + l1_index * sizeof(tmp),
 380                 &tmp, sizeof(tmp)) < 0)
 381             return 0;
 382         new_l2_table = 1;
 383     }
 384     for(i = 0; i < L2_CACHE_SIZE; i++) {
 385         if (l2_offset == s->l2_cache_offsets[i]) {
 386             /* increment the hit count */
 387             if (++s->l2_cache_counts[i] == 0xffffffff) {
 388                 for(j = 0; j < L2_CACHE_SIZE; j++) {
 389                     s->l2_cache_counts[j] >>= 1;
 390                 }
 391             }
 392             l2_table = s->l2_cache + (i << s->l2_bits);
 393             goto found;
 394         }
 395     }
 396     /* not found: load a new entry in the least used one */
 397     min_index = 0;
 398     min_count = 0xffffffff;
 399     for(i = 0; i < L2_CACHE_SIZE; i++) {
 400         if (s->l2_cache_counts[i] < min_count) {
 401             min_count = s->l2_cache_counts[i];
 402             min_index = i;
 403         }
 404     }
 405     l2_table = s->l2_cache + (min_index << s->l2_bits);
 406     if (new_l2_table) {
 407         memset(l2_table, 0, s->l2_size * sizeof(uint64_t));
 408         if (bdrv_pwrite_sync(bs->file, l2_offset, l2_table,
 409                 s->l2_size * sizeof(uint64_t)) < 0)
 410             return 0;
 411     } else {
 412         if (bdrv_pread(bs->file, l2_offset, l2_table, s->l2_size * sizeof(uint64_t)) !=
 413             s->l2_size * sizeof(uint64_t))
 414             return 0;
 415     }
 416     s->l2_cache_offsets[min_index] = l2_offset;
 417     s->l2_cache_counts[min_index] = 1;
 418  found:
 419     l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1);
 420     cluster_offset = be64_to_cpu(l2_table[l2_index]);
 421     if (!cluster_offset ||
 422         ((cluster_offset & QCOW_OFLAG_COMPRESSED) && allocate == 1)) {
 423         if (!allocate)
 424             return 0;
 425         /* allocate a new cluster */
 426         if ((cluster_offset & QCOW_OFLAG_COMPRESSED) &&
 427             (n_end - n_start) < s->cluster_sectors) {
 428             /* if the cluster is already compressed, we must
 429                decompress it in the case it is not completely
 430                overwritten */
 431             if (decompress_cluster(bs, cluster_offset) < 0)
 432                 return 0;
 433             cluster_offset = bdrv_getlength(bs->file);
 434             cluster_offset = (cluster_offset + s->cluster_size - 1) &
 435                 ~(s->cluster_size - 1);
 436             /* write the cluster content */
 437             if (bdrv_pwrite(bs->file, cluster_offset, s->cluster_cache, s->cluster_size) !=
 438                 s->cluster_size)
 439                 return -1;
 440         } else {
 441             cluster_offset = bdrv_getlength(bs->file);
 442             if (allocate == 1) {
 443                 /* round to cluster size */
 444                 cluster_offset = (cluster_offset + s->cluster_size - 1) &
 445                     ~(s->cluster_size - 1);
 446                 bdrv_truncate(bs->file, cluster_offset + s->cluster_size);
 447                 /* if encrypted, we must initialize the cluster
 448                    content which won't be written */
 449                 if (bs->encrypted &&
 450                     (n_end - n_start) < s->cluster_sectors) {
 451                     uint64_t start_sect;
 452                     assert(s->cipher);
 453                     start_sect = (offset & ~(s->cluster_size - 1)) >> 9;
 454                     memset(s->cluster_data + 512, 0x00, 512);
 455                     for(i = 0; i < s->cluster_sectors; i++) {
 456                         if (i < n_start || i >= n_end) {
 457                             Error *err = NULL;
 458                             if (encrypt_sectors(s, start_sect + i,
 459                                                 s->cluster_data,
 460                                                 s->cluster_data + 512, 1,
 461                                                 true, &err) < 0) {
 462                                 error_free(err);
 463                                 errno = EIO;
 464                                 return -1;
 465                             }
 466                             if (bdrv_pwrite(bs->file, cluster_offset + i * 512,
 467                                             s->cluster_data, 512) != 512)
 468                                 return -1;
 469                         }
 470                     }
 471                 }
 472             } else if (allocate == 2) {
 473                 cluster_offset |= QCOW_OFLAG_COMPRESSED |
 474                     (uint64_t)compressed_size << (63 - s->cluster_bits);
 475             }
 476         }
 477         /* update L2 table */
 478         tmp = cpu_to_be64(cluster_offset);
 479         l2_table[l2_index] = tmp;
 480         if (bdrv_pwrite_sync(bs->file, l2_offset + l2_index * sizeof(tmp),
 481                 &tmp, sizeof(tmp)) < 0)
 482             return 0;
 483     }
 484     return cluster_offset;
 485 }
 486
 487 static int64_t coroutine_fn qcow_co_get_block_status(BlockDriverState *bs,
 488         int64_t sector_num, int nb_sectors, int *pnum)
 489 {
 490     BDRVQcowState *s = bs->opaque;
 491     int index_in_cluster, n;
 492     uint64_t cluster_offset;
 493
 494     qemu_co_mutex_lock(&s->lock);
 495     cluster_offset = get_cluster_offset(bs, sector_num << 9, 0, 0, 0, 0);
 496     qemu_co_mutex_unlock(&s->lock);
 497     index_in_cluster = sector_num & (s->cluster_sectors - 1);
 498     n = s->cluster_sectors - index_in_cluster;
 499     if (n > nb_sectors)
 500         n = nb_sectors;
 501     *pnum = n;
 502     if (!cluster_offset) {
 503         return 0;
 504     }
 505     if ((cluster_offset & QCOW_OFLAG_COMPRESSED) || s->cipher) {
 506         return BDRV_BLOCK_DATA;
 507     }
 508     cluster_offset |= (index_in_cluster << BDRV_SECTOR_BITS);
 509     return BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID | cluster_offset;
 510 }
 511
 512 static int decompress_buffer(uint8_t *out_buf, int out_buf_size,
 513                              const uint8_t *buf, int buf_size)
 514 {
 515     z_stream strm1, *strm = &strm1;
 516     int ret, out_len;
 517
 518     memset(strm, 0, sizeof(*strm));
 519
 520     strm->next_in = (uint8_t *)buf;
 521     strm->avail_in = buf_size;
 522     strm->next_out = out_buf;
 523     strm->avail_out = out_buf_size;
 524
 525     ret = inflateInit2(strm, -12);
 526     if (ret != Z_OK)
 527         return -1;
 528     ret = inflate(strm, Z_FINISH);
 529     out_len = strm->next_out - out_buf;
 530     if ((ret != Z_STREAM_END && ret != Z_BUF_ERROR) ||
 531         out_len != out_buf_size) {
 532         inflateEnd(strm);
 533         return -1;
 534     }
 535     inflateEnd(strm);
 536     return 0;
 537 }
 538
 539 static int decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset)
 540 {
 541     BDRVQcowState *s = bs->opaque;
 542     int ret, csize;
 543     uint64_t coffset;
 544
 545     coffset = cluster_offset & s->cluster_offset_mask;
 546     if (s->cluster_cache_offset != coffset) {
 547         csize = cluster_offset >> (63 - s->cluster_bits);
 548         csize &= (s->cluster_size - 1);
 549         ret = bdrv_pread(bs->file, coffset, s->cluster_data, csize);
 550         if (ret != csize)
 551             return -1;
 552         if (decompress_buffer(s->cluster_cache, s->cluster_size,
 553                               s->cluster_data, csize) < 0) {
 554             return -1;
 555         }
 556         s->cluster_cache_offset = coffset;
 557     }
 558     return 0;
 559 }
 560
 561 static coroutine_fn int qcow_co_readv(BlockDriverState *bs, int64_t sector_num,
 562                          int nb_sectors, QEMUIOVector *qiov)
 563 {
 564     BDRVQcowState *s = bs->opaque;
 565     int index_in_cluster;
 566     int ret = 0, n;
 567     uint64_t cluster_offset;
 568     struct iovec hd_iov;
 569     QEMUIOVector hd_qiov;
 570     uint8_t *buf;
 571     void *orig_buf;
 572     Error *err = NULL;
 573
 574     if (qiov->niov > 1) {
 575         buf = orig_buf = qemu_try_blockalign(bs, qiov->size);
 576         if (buf == NULL) {
 577             return -ENOMEM;
 578         }
 579     } else {
 580         orig_buf = NULL;
 581         buf = (uint8_t *)qiov->iov->iov_base;
 582     }
 583
 584     qemu_co_mutex_lock(&s->lock);
 585
 586     while (nb_sectors != 0) {
 587         /* prepare next request */
 588         cluster_offset = get_cluster_offset(bs, sector_num << 9,
 589                                                  0, 0, 0, 0);
 590         index_in_cluster = sector_num & (s->cluster_sectors - 1);
 591         n = s->cluster_sectors - index_in_cluster;
 592         if (n > nb_sectors) {
 593             n = nb_sectors;
 594         }
 595
 596         if (!cluster_offset) {
 597             if (bs->backing_hd) {
 598                 /* read from the base image */
 599                 hd_iov.iov_base = (void *)buf;
 600                 hd_iov.iov_len = n * 512;
 601                 qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
 602                 qemu_co_mutex_unlock(&s->lock);
 603                 ret = bdrv_co_readv(bs->backing_hd, sector_num,
 604                                     n, &hd_qiov);
 605                 qemu_co_mutex_lock(&s->lock);
 606                 if (ret < 0) {
 607                     goto fail;
 608                 }
 609             } else {
 610                 /* Note: in this case, no need to wait */
 611                 memset(buf, 0, 512 * n);
 612             }
 613         } else if (cluster_offset & QCOW_OFLAG_COMPRESSED) {
 614             /* add AIO support for compressed blocks ? */
 615             if (decompress_cluster(bs, cluster_offset) < 0) {
 616                 goto fail;
 617             }
 618             memcpy(buf,
 619                    s->cluster_cache + index_in_cluster * 512, 512 * n);
 620         } else {
 621             if ((cluster_offset & 511) != 0) {
 622                 goto fail;
 623             }
 624             hd_iov.iov_base = (void *)buf;
 625             hd_iov.iov_len = n * 512;
 626             qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
 627             qemu_co_mutex_unlock(&s->lock);
 628             ret = bdrv_co_readv(bs->file,
 629                                 (cluster_offset >> 9) + index_in_cluster,
 630                                 n, &hd_qiov);
 631             qemu_co_mutex_lock(&s->lock);
 632             if (ret < 0) {
 633                 break;
 634             }
 635             if (bs->encrypted) {
 636                 assert(s->cipher);
 637                 if (encrypt_sectors(s, sector_num, buf, buf,
 638                                     n, false, &err) < 0) {
 639                     goto fail;
 640                 }
 641             }
 642         }
 643         ret = 0;
 644
 645         nb_sectors -= n;
 646         sector_num += n;
 647         buf += n * 512;
 648     }
 649
 650 done:
 651     qemu_co_mutex_unlock(&s->lock);
 652
 653     if (qiov->niov > 1) {
 654         qemu_iovec_from_buf(qiov, 0, orig_buf, qiov->size);
 655         qemu_vfree(orig_buf);
 656     }
 657
 658     return ret;
 659
 660 fail:
 661     error_free(err);
 662     ret = -EIO;
 663     goto done;
 664 }
 665
 666 static coroutine_fn int qcow_co_writev(BlockDriverState *bs, int64_t sector_num,
 667                           int nb_sectors, QEMUIOVector *qiov)
 668 {
 669     BDRVQcowState *s = bs->opaque;
 670     int index_in_cluster;
 671     uint64_t cluster_offset;
 672     const uint8_t *src_buf;
 673     int ret = 0, n;
 674     uint8_t *cluster_data = NULL;
 675     struct iovec hd_iov;
 676     QEMUIOVector hd_qiov;
 677     uint8_t *buf;
 678     void *orig_buf;
 679
 680     s->cluster_cache_offset = -1; /* disable compressed cache */
 681
 682     if (qiov->niov > 1) {
 683         buf = orig_buf = qemu_try_blockalign(bs, qiov->size);
 684         if (buf == NULL) {
 685             return -ENOMEM;
 686         }
 687         qemu_iovec_to_buf(qiov, 0, buf, qiov->size);
 688     } else {
 689         orig_buf = NULL;
 690         buf = (uint8_t *)qiov->iov->iov_base;
 691     }
 692
 693     qemu_co_mutex_lock(&s->lock);
 694
 695     while (nb_sectors != 0) {
 696
 697         index_in_cluster = sector_num & (s->cluster_sectors - 1);
 698         n = s->cluster_sectors - index_in_cluster;
 699         if (n > nb_sectors) {
 700             n = nb_sectors;
 701         }
 702         cluster_offset = get_cluster_offset(bs, sector_num << 9, 1, 0,
 703                                             index_in_cluster,
 704                                             index_in_cluster + n);
 705         if (!cluster_offset || (cluster_offset & 511) != 0) {
 706             ret = -EIO;
 707             break;
 708         }
 709         if (bs->encrypted) {
 710             Error *err = NULL;
 711             assert(s->cipher);
 712             if (!cluster_data) {
 713                 cluster_data = g_malloc0(s->cluster_size);
 714             }
 715             if (encrypt_sectors(s, sector_num, cluster_data, buf,
 716                                 n, true, &err) < 0) {
 717                 error_free(err);
 718                 ret = -EIO;
 719                 break;
 720             }
 721             src_buf = cluster_data;
 722         } else {
 723             src_buf = buf;
 724         }
 725
 726         hd_iov.iov_base = (void *)src_buf;
 727         hd_iov.iov_len = n * 512;
 728         qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
 729         qemu_co_mutex_unlock(&s->lock);
 730         ret = bdrv_co_writev(bs->file,
 731                              (cluster_offset >> 9) + index_in_cluster,
 732                              n, &hd_qiov);
 733         qemu_co_mutex_lock(&s->lock);
 734         if (ret < 0) {
 735             break;
 736         }
 737         ret = 0;
 738
 739         nb_sectors -= n;
 740         sector_num += n;
 741         buf += n * 512;
 742     }
 743     qemu_co_mutex_unlock(&s->lock);
 744
 745     if (qiov->niov > 1) {
 746         qemu_vfree(orig_buf);
 747     }
 748     g_free(cluster_data);
 749
 750     return ret;
 751 }
 752
 753 static void qcow_close(BlockDriverState *bs)
 754 {
 755     BDRVQcowState *s = bs->opaque;
 756
 757     qcrypto_cipher_free(s->cipher);
 758     s->cipher = NULL;
 759     g_free(s->l1_table);
 760     qemu_vfree(s->l2_cache);
 761     g_free(s->cluster_cache);
 762     g_free(s->cluster_data);
 763
 764     migrate_del_blocker(s->migration_blocker);
 765     error_free(s->migration_blocker);
 766 }
 767
 768 static int qcow_create(const char *filename, QemuOpts *opts, Error **errp)
 769 {
 770     int header_size, backing_filename_len, l1_size, shift, i;
 771     QCowHeader header;
 772     uint8_t *tmp;
 773     int64_t total_size = 0;
 774     char *backing_file = NULL;
 775     int flags = 0;
 776     Error *local_err = NULL;
 777     int ret;
 778     BlockDriverState *qcow_bs;
 779
 780     /* Read out options */
 781     total_size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0),
 782                           BDRV_SECTOR_SIZE);
 783     backing_file = qemu_opt_get_del(opts, BLOCK_OPT_BACKING_FILE);
 784     if (qemu_opt_get_bool_del(opts, BLOCK_OPT_ENCRYPT, false)) {
 785         flags |= BLOCK_FLAG_ENCRYPT;
 786     }
 787
 788     ret = bdrv_create_file(filename, opts, &local_err);
 789     if (ret < 0) {
 790         error_propagate(errp, local_err);
 791         goto cleanup;
 792     }
 793
 794     qcow_bs = NULL;
 795     ret = bdrv_open(&qcow_bs, filename, NULL, NULL,
 796                     BDRV_O_RDWR | BDRV_O_PROTOCOL, &local_err);
 797     if (ret < 0) {
 798         error_propagate(errp, local_err);
 799         goto cleanup;
 800     }
 801
 802     ret = bdrv_truncate(qcow_bs, 0);
 803     if (ret < 0) {
 804         goto exit;
 805     }
 806
 807     memset(&header, 0, sizeof(header));
 808     header.magic = cpu_to_be32(QCOW_MAGIC);
 809     header.version = cpu_to_be32(QCOW_VERSION);
 810     header.size = cpu_to_be64(total_size);
 811     header_size = sizeof(header);
 812     backing_filename_len = 0;
 813     if (backing_file) {
 814         if (strcmp(backing_file, "fat:")) {
 815             header.backing_file_offset = cpu_to_be64(header_size);
 816             backing_filename_len = strlen(backing_file);
 817             header.backing_file_size = cpu_to_be32(backing_filename_len);
 818             header_size += backing_filename_len;
 819         } else {
 820             /* special backing file for vvfat */
 821             backing_file = NULL;
 822         }
 823         header.cluster_bits = 9; /* 512 byte cluster to avoid copying
 824                                     unmodified sectors */
 825         header.l2_bits = 12; /* 32 KB L2 tables */
 826     } else {
 827         header.cluster_bits = 12; /* 4 KB clusters */
 828         header.l2_bits = 9; /* 4 KB L2 tables */
 829     }
 830     header_size = (header_size + 7) & ~7;
 831     shift = header.cluster_bits + header.l2_bits;
 832     l1_size = (total_size + (1LL << shift) - 1) >> shift;
 833
 834     header.l1_table_offset = cpu_to_be64(header_size);
 835     if (flags & BLOCK_FLAG_ENCRYPT) {
 836         header.crypt_method = cpu_to_be32(QCOW_CRYPT_AES);
 837     } else {
 838         header.crypt_method = cpu_to_be32(QCOW_CRYPT_NONE);
 839     }
 840
 841     /* write all the data */
 842     ret = bdrv_pwrite(qcow_bs, 0, &header, sizeof(header));
 843     if (ret != sizeof(header)) {
 844         goto exit;
 845     }
 846
 847     if (backing_file) {
 848         ret = bdrv_pwrite(qcow_bs, sizeof(header),
 849             backing_file, backing_filename_len);
 850         if (ret != backing_filename_len) {
 851             goto exit;
 852         }
 853     }
 854
 855     tmp = g_malloc0(BDRV_SECTOR_SIZE);
 856     for (i = 0; i < ((sizeof(uint64_t)*l1_size + BDRV_SECTOR_SIZE - 1)/
 857         BDRV_SECTOR_SIZE); i++) {
 858         ret = bdrv_pwrite(qcow_bs, header_size +
 859             BDRV_SECTOR_SIZE*i, tmp, BDRV_SECTOR_SIZE);
 860         if (ret != BDRV_SECTOR_SIZE) {
 861             g_free(tmp);
 862             goto exit;
 863         }
 864     }
 865
 866     g_free(tmp);
 867     ret = 0;
 868 exit:
 869     bdrv_unref(qcow_bs);
 870 cleanup:
 871     g_free(backing_file);
 872     return ret;
 873 }
 874
 875 static int qcow_make_empty(BlockDriverState *bs)
 876 {
 877     BDRVQcowState *s = bs->opaque;
 878     uint32_t l1_length = s->l1_size * sizeof(uint64_t);
 879     int ret;
 880
 881     memset(s->l1_table, 0, l1_length);
 882     if (bdrv_pwrite_sync(bs->file, s->l1_table_offset, s->l1_table,
 883             l1_length) < 0)
 884         return -1;
 885     ret = bdrv_truncate(bs->file, s->l1_table_offset + l1_length);
 886     if (ret < 0)
 887         return ret;
 888
 889     memset(s->l2_cache, 0, s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t));
 890     memset(s->l2_cache_offsets, 0, L2_CACHE_SIZE * sizeof(uint64_t));
 891     memset(s->l2_cache_counts, 0, L2_CACHE_SIZE * sizeof(uint32_t));
 892
 893     return 0;
 894 }
 895
 896 /* XXX: put compressed sectors first, then all the cluster aligned
 897    tables to avoid losing bytes in alignment */
 898 static int qcow_write_compressed(BlockDriverState *bs, int64_t sector_num,
 899                                  const uint8_t *buf, int nb_sectors)
 900 {
 901     BDRVQcowState *s = bs->opaque;
 902     z_stream strm;
 903     int ret, out_len;
 904     uint8_t *out_buf;
 905     uint64_t cluster_offset;
 906
 907     if (nb_sectors != s->cluster_sectors) {
 908         ret = -EINVAL;
 909
 910         /* Zero-pad last write if image size is not cluster aligned */
 911         if (sector_num + nb_sectors == bs->total_sectors &&
 912             nb_sectors < s->cluster_sectors) {
 913             uint8_t *pad_buf = qemu_blockalign(bs, s->cluster_size);
 914             memset(pad_buf, 0, s->cluster_size);
 915             memcpy(pad_buf, buf, nb_sectors * BDRV_SECTOR_SIZE);
 916             ret = qcow_write_compressed(bs, sector_num,
 917                                         pad_buf, s->cluster_sectors);
 918             qemu_vfree(pad_buf);
 919         }
 920         return ret;
 921     }
 922
 923     out_buf = g_malloc(s->cluster_size + (s->cluster_size / 1000) + 128);
 924
 925     /* best compression, small window, no zlib header */
 926     memset(&strm, 0, sizeof(strm));
 927     ret = deflateInit2(&strm, Z_DEFAULT_COMPRESSION,
 928                        Z_DEFLATED, -12,
 929                        9, Z_DEFAULT_STRATEGY);
 930     if (ret != 0) {
 931         ret = -EINVAL;
 932         goto fail;
 933     }
 934
 935     strm.avail_in = s->cluster_size;
 936     strm.next_in = (uint8_t *)buf;
 937     strm.avail_out = s->cluster_size;
 938     strm.next_out = out_buf;
 939
 940     ret = deflate(&strm, Z_FINISH);
 941     if (ret != Z_STREAM_END && ret != Z_OK) {
 942         deflateEnd(&strm);
 943         ret = -EINVAL;
 944         goto fail;
 945     }
 946     out_len = strm.next_out - out_buf;
 947
 948     deflateEnd(&strm);
 949
 950     if (ret != Z_STREAM_END || out_len >= s->cluster_size) {
 951         /* could not compress: write normal cluster */
 952         ret = bdrv_write(bs, sector_num, buf, s->cluster_sectors);
 953         if (ret < 0) {
 954             goto fail;
 955         }
 956     } else {
 957         cluster_offset = get_cluster_offset(bs, sector_num << 9, 2,
 958                                             out_len, 0, 0);
 959         if (cluster_offset == 0) {
 960             ret = -EIO;
 961             goto fail;
 962         }
 963
 964         cluster_offset &= s->cluster_offset_mask;
 965         ret = bdrv_pwrite(bs->file, cluster_offset, out_buf, out_len);
 966         if (ret < 0) {
 967             goto fail;
 968         }
 969     }
 970
 971     ret = 0;
 972 fail:
 973     g_free(out_buf);
 974     return ret;
 975 }
 976
 977 static int qcow_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
 978 {
 979     BDRVQcowState *s = bs->opaque;
 980     bdi->cluster_size = s->cluster_size;
 981     return 0;
 982 }
 983
 984 static QemuOptsList qcow_create_opts = {
 985     .name = "qcow-create-opts",
 986     .head = QTAILQ_HEAD_INITIALIZER(qcow_create_opts.head),
 987     .desc = {
 988         {
 989             .name = BLOCK_OPT_SIZE,
 990             .type = QEMU_OPT_SIZE,
 991             .help = "Virtual disk size"
 992         },
 993         {
 994             .name = BLOCK_OPT_BACKING_FILE,
 995             .type = QEMU_OPT_STRING,
 996             .help = "File name of a base image"
 997         },
 998         {
 999             .name = BLOCK_OPT_ENCRYPT,
1000             .type = QEMU_OPT_BOOL,
1001             .help = "Encrypt the image",
1002             .def_value_str = "off"
1003         },
1004         { /* end of list */ }
1005     }
1006 };
1007
1008 static BlockDriver bdrv_qcow = {
1009     .format_name        = "qcow",
1010     .instance_size      = sizeof(BDRVQcowState),
1011     .bdrv_probe         = qcow_probe,
1012     .bdrv_open          = qcow_open,
1013     .bdrv_close         = qcow_close,
1014     .bdrv_reopen_prepare    = qcow_reopen_prepare,
1015     .bdrv_create            = qcow_create,
1016     .bdrv_has_zero_init     = bdrv_has_zero_init_1,
1017     .supports_backing       = true,
1018
1019     .bdrv_co_readv          = qcow_co_readv,
1020     .bdrv_co_writev         = qcow_co_writev,
1021     .bdrv_co_get_block_status   = qcow_co_get_block_status,
1022
1023     .bdrv_set_key           = qcow_set_key,
1024     .bdrv_make_empty        = qcow_make_empty,
1025     .bdrv_write_compressed  = qcow_write_compressed,
1026     .bdrv_get_info          = qcow_get_info,
1027
1028     .create_opts            = &qcow_create_opts,
1029 };
1030
1031 static void bdrv_qcow_init(void)
1032 {
1033     bdrv_register(&bdrv_qcow);
1034 }
1035
1036 block_init(bdrv_qcow_init);