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