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 #include "qemu-common.h" 25 #include "block_int.h" 26 #include "module.h" 27 #include <zlib.h> 28 #include "aes.h" 29 #include "block/qcow2.h" 30 #include "qemu-error.h" 31 #include "qerror.h" 32 33 /* 34 Differences with QCOW: 35 36 - Support for multiple incremental snapshots. 37 - Memory management by reference counts. 38 - Clusters which have a reference count of one have the bit 39 QCOW_OFLAG_COPIED to optimize write performance. 40 - Size of compressed clusters is stored in sectors to reduce bit usage 41 in the cluster offsets. 42 - Support for storing additional data (such as the VM state) in the 43 snapshots. 44 - If a backing store is used, the cluster size is not constrained 45 (could be backported to QCOW). 46 - L2 tables have always a size of one cluster. 47 */ 48 49 50 typedef struct { 51 uint32_t magic; 52 uint32_t len; 53 } QCowExtension; 54 #define QCOW2_EXT_MAGIC_END 0 55 #define QCOW2_EXT_MAGIC_BACKING_FORMAT 0xE2792ACA 56 57 static int qcow2_probe(const uint8_t *buf, int buf_size, const char *filename) 58 { 59 const QCowHeader *cow_header = (const void *)buf; 60 61 if (buf_size >= sizeof(QCowHeader) && 62 be32_to_cpu(cow_header->magic) == QCOW_MAGIC && 63 be32_to_cpu(cow_header->version) >= QCOW_VERSION) 64 return 100; 65 else 66 return 0; 67 } 68 69 70 /* 71 * read qcow2 extension and fill bs 72 * start reading from start_offset 73 * finish reading upon magic of value 0 or when end_offset reached 74 * unknown magic is skipped (future extension this version knows nothing about) 75 * return 0 upon success, non-0 otherwise 76 */ 77 static int qcow2_read_extensions(BlockDriverState *bs, uint64_t start_offset, 78 uint64_t end_offset) 79 { 80 QCowExtension ext; 81 uint64_t offset; 82 83 #ifdef DEBUG_EXT 84 printf("qcow2_read_extensions: start=%ld end=%ld\n", start_offset, end_offset); 85 #endif 86 offset = start_offset; 87 while (offset < end_offset) { 88 89 #ifdef DEBUG_EXT 90 BDRVQcowState *s = bs->opaque; 91 /* Sanity check */ 92 if (offset > s->cluster_size) 93 printf("qcow2_read_extension: suspicious offset %lu\n", offset); 94 95 printf("attempting to read extended header in offset %lu\n", offset); 96 #endif 97 98 if (bdrv_pread(bs->file, offset, &ext, sizeof(ext)) != sizeof(ext)) { 99 fprintf(stderr, "qcow2_read_extension: ERROR: " 100 "pread fail from offset %" PRIu64 "\n", 101 offset); 102 return 1; 103 } 104 be32_to_cpus(&ext.magic); 105 be32_to_cpus(&ext.len); 106 offset += sizeof(ext); 107 #ifdef DEBUG_EXT 108 printf("ext.magic = 0x%x\n", ext.magic); 109 #endif 110 switch (ext.magic) { 111 case QCOW2_EXT_MAGIC_END: 112 return 0; 113 114 case QCOW2_EXT_MAGIC_BACKING_FORMAT: 115 if (ext.len >= sizeof(bs->backing_format)) { 116 fprintf(stderr, "ERROR: ext_backing_format: len=%u too large" 117 " (>=%zu)\n", 118 ext.len, sizeof(bs->backing_format)); 119 return 2; 120 } 121 if (bdrv_pread(bs->file, offset , bs->backing_format, 122 ext.len) != ext.len) 123 return 3; 124 bs->backing_format[ext.len] = '\0'; 125 #ifdef DEBUG_EXT 126 printf("Qcow2: Got format extension %s\n", bs->backing_format); 127 #endif 128 offset = ((offset + ext.len + 7) & ~7); 129 break; 130 131 default: 132 /* unknown magic -- just skip it */ 133 offset = ((offset + ext.len + 7) & ~7); 134 break; 135 } 136 } 137 138 return 0; 139 } 140 141 142 static int qcow2_open(BlockDriverState *bs, int flags) 143 { 144 BDRVQcowState *s = bs->opaque; 145 int len, i, ret = 0; 146 QCowHeader header; 147 uint64_t ext_end; 148 bool writethrough; 149 150 ret = bdrv_pread(bs->file, 0, &header, sizeof(header)); 151 if (ret < 0) { 152 goto fail; 153 } 154 be32_to_cpus(&header.magic); 155 be32_to_cpus(&header.version); 156 be64_to_cpus(&header.backing_file_offset); 157 be32_to_cpus(&header.backing_file_size); 158 be64_to_cpus(&header.size); 159 be32_to_cpus(&header.cluster_bits); 160 be32_to_cpus(&header.crypt_method); 161 be64_to_cpus(&header.l1_table_offset); 162 be32_to_cpus(&header.l1_size); 163 be64_to_cpus(&header.refcount_table_offset); 164 be32_to_cpus(&header.refcount_table_clusters); 165 be64_to_cpus(&header.snapshots_offset); 166 be32_to_cpus(&header.nb_snapshots); 167 168 if (header.magic != QCOW_MAGIC) { 169 ret = -EINVAL; 170 goto fail; 171 } 172 if (header.version != QCOW_VERSION) { 173 char version[64]; 174 snprintf(version, sizeof(version), "QCOW version %d", header.version); 175 qerror_report(QERR_UNKNOWN_BLOCK_FORMAT_FEATURE, 176 bs->device_name, "qcow2", version); 177 ret = -ENOTSUP; 178 goto fail; 179 } 180 if (header.cluster_bits < MIN_CLUSTER_BITS || 181 header.cluster_bits > MAX_CLUSTER_BITS) { 182 ret = -EINVAL; 183 goto fail; 184 } 185 if (header.crypt_method > QCOW_CRYPT_AES) { 186 ret = -EINVAL; 187 goto fail; 188 } 189 s->crypt_method_header = header.crypt_method; 190 if (s->crypt_method_header) { 191 bs->encrypted = 1; 192 } 193 s->cluster_bits = header.cluster_bits; 194 s->cluster_size = 1 << s->cluster_bits; 195 s->cluster_sectors = 1 << (s->cluster_bits - 9); 196 s->l2_bits = s->cluster_bits - 3; /* L2 is always one cluster */ 197 s->l2_size = 1 << s->l2_bits; 198 bs->total_sectors = header.size / 512; 199 s->csize_shift = (62 - (s->cluster_bits - 8)); 200 s->csize_mask = (1 << (s->cluster_bits - 8)) - 1; 201 s->cluster_offset_mask = (1LL << s->csize_shift) - 1; 202 s->refcount_table_offset = header.refcount_table_offset; 203 s->refcount_table_size = 204 header.refcount_table_clusters << (s->cluster_bits - 3); 205 206 s->snapshots_offset = header.snapshots_offset; 207 s->nb_snapshots = header.nb_snapshots; 208 209 /* read the level 1 table */ 210 s->l1_size = header.l1_size; 211 s->l1_vm_state_index = size_to_l1(s, header.size); 212 /* the L1 table must contain at least enough entries to put 213 header.size bytes */ 214 if (s->l1_size < s->l1_vm_state_index) { 215 ret = -EINVAL; 216 goto fail; 217 } 218 s->l1_table_offset = header.l1_table_offset; 219 if (s->l1_size > 0) { 220 s->l1_table = g_malloc0( 221 align_offset(s->l1_size * sizeof(uint64_t), 512)); 222 ret = bdrv_pread(bs->file, s->l1_table_offset, s->l1_table, 223 s->l1_size * sizeof(uint64_t)); 224 if (ret < 0) { 225 goto fail; 226 } 227 for(i = 0;i < s->l1_size; i++) { 228 be64_to_cpus(&s->l1_table[i]); 229 } 230 } 231 232 /* alloc L2 table/refcount block cache */ 233 writethrough = ((flags & BDRV_O_CACHE_WB) == 0); 234 s->l2_table_cache = qcow2_cache_create(bs, L2_CACHE_SIZE, writethrough); 235 s->refcount_block_cache = qcow2_cache_create(bs, REFCOUNT_CACHE_SIZE, 236 writethrough); 237 238 s->cluster_cache = g_malloc(s->cluster_size); 239 /* one more sector for decompressed data alignment */ 240 s->cluster_data = qemu_blockalign(bs, QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size 241 + 512); 242 s->cluster_cache_offset = -1; 243 s->flags = flags; 244 245 ret = qcow2_refcount_init(bs); 246 if (ret != 0) { 247 goto fail; 248 } 249 250 QLIST_INIT(&s->cluster_allocs); 251 252 /* read qcow2 extensions */ 253 if (header.backing_file_offset) { 254 ext_end = header.backing_file_offset; 255 } else { 256 ext_end = s->cluster_size; 257 } 258 if (qcow2_read_extensions(bs, sizeof(header), ext_end)) { 259 ret = -EINVAL; 260 goto fail; 261 } 262 263 /* read the backing file name */ 264 if (header.backing_file_offset != 0) { 265 len = header.backing_file_size; 266 if (len > 1023) { 267 len = 1023; 268 } 269 ret = bdrv_pread(bs->file, header.backing_file_offset, 270 bs->backing_file, len); 271 if (ret < 0) { 272 goto fail; 273 } 274 bs->backing_file[len] = '\0'; 275 } 276 277 ret = qcow2_read_snapshots(bs); 278 if (ret < 0) { 279 goto fail; 280 } 281 282 /* Initialise locks */ 283 qemu_co_mutex_init(&s->lock); 284 285 #ifdef DEBUG_ALLOC 286 { 287 BdrvCheckResult result = {0}; 288 qcow2_check_refcounts(bs, &result); 289 } 290 #endif 291 return ret; 292 293 fail: 294 qcow2_free_snapshots(bs); 295 qcow2_refcount_close(bs); 296 g_free(s->l1_table); 297 if (s->l2_table_cache) { 298 qcow2_cache_destroy(bs, s->l2_table_cache); 299 } 300 g_free(s->cluster_cache); 301 qemu_vfree(s->cluster_data); 302 return ret; 303 } 304 305 static int qcow2_set_key(BlockDriverState *bs, const char *key) 306 { 307 BDRVQcowState *s = bs->opaque; 308 uint8_t keybuf[16]; 309 int len, i; 310 311 memset(keybuf, 0, 16); 312 len = strlen(key); 313 if (len > 16) 314 len = 16; 315 /* XXX: we could compress the chars to 7 bits to increase 316 entropy */ 317 for(i = 0;i < len;i++) { 318 keybuf[i] = key[i]; 319 } 320 s->crypt_method = s->crypt_method_header; 321 322 if (AES_set_encrypt_key(keybuf, 128, &s->aes_encrypt_key) != 0) 323 return -1; 324 if (AES_set_decrypt_key(keybuf, 128, &s->aes_decrypt_key) != 0) 325 return -1; 326 #if 0 327 /* test */ 328 { 329 uint8_t in[16]; 330 uint8_t out[16]; 331 uint8_t tmp[16]; 332 for(i=0;i<16;i++) 333 in[i] = i; 334 AES_encrypt(in, tmp, &s->aes_encrypt_key); 335 AES_decrypt(tmp, out, &s->aes_decrypt_key); 336 for(i = 0; i < 16; i++) 337 printf(" %02x", tmp[i]); 338 printf("\n"); 339 for(i = 0; i < 16; i++) 340 printf(" %02x", out[i]); 341 printf("\n"); 342 } 343 #endif 344 return 0; 345 } 346 347 static int coroutine_fn qcow2_co_is_allocated(BlockDriverState *bs, 348 int64_t sector_num, int nb_sectors, int *pnum) 349 { 350 BDRVQcowState *s = bs->opaque; 351 uint64_t cluster_offset; 352 int ret; 353 354 *pnum = nb_sectors; 355 /* FIXME We can get errors here, but the bdrv_co_is_allocated interface 356 * can't pass them on today */ 357 qemu_co_mutex_lock(&s->lock); 358 ret = qcow2_get_cluster_offset(bs, sector_num << 9, pnum, &cluster_offset); 359 qemu_co_mutex_unlock(&s->lock); 360 if (ret < 0) { 361 *pnum = 0; 362 } 363 364 return (cluster_offset != 0); 365 } 366 367 /* handle reading after the end of the backing file */ 368 int qcow2_backing_read1(BlockDriverState *bs, QEMUIOVector *qiov, 369 int64_t sector_num, int nb_sectors) 370 { 371 int n1; 372 if ((sector_num + nb_sectors) <= bs->total_sectors) 373 return nb_sectors; 374 if (sector_num >= bs->total_sectors) 375 n1 = 0; 376 else 377 n1 = bs->total_sectors - sector_num; 378 379 qemu_iovec_memset_skip(qiov, 0, 512 * (nb_sectors - n1), 512 * n1); 380 381 return n1; 382 } 383 384 static coroutine_fn int qcow2_co_readv(BlockDriverState *bs, int64_t sector_num, 385 int remaining_sectors, QEMUIOVector *qiov) 386 { 387 BDRVQcowState *s = bs->opaque; 388 int index_in_cluster, n1; 389 int ret; 390 int cur_nr_sectors; /* number of sectors in current iteration */ 391 uint64_t cluster_offset = 0; 392 uint64_t bytes_done = 0; 393 QEMUIOVector hd_qiov; 394 uint8_t *cluster_data = NULL; 395 396 qemu_iovec_init(&hd_qiov, qiov->niov); 397 398 qemu_co_mutex_lock(&s->lock); 399 400 while (remaining_sectors != 0) { 401 402 /* prepare next request */ 403 cur_nr_sectors = remaining_sectors; 404 if (s->crypt_method) { 405 cur_nr_sectors = MIN(cur_nr_sectors, 406 QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors); 407 } 408 409 ret = qcow2_get_cluster_offset(bs, sector_num << 9, 410 &cur_nr_sectors, &cluster_offset); 411 if (ret < 0) { 412 goto fail; 413 } 414 415 index_in_cluster = sector_num & (s->cluster_sectors - 1); 416 417 qemu_iovec_reset(&hd_qiov); 418 qemu_iovec_copy(&hd_qiov, qiov, bytes_done, 419 cur_nr_sectors * 512); 420 421 if (!cluster_offset) { 422 423 if (bs->backing_hd) { 424 /* read from the base image */ 425 n1 = qcow2_backing_read1(bs->backing_hd, &hd_qiov, 426 sector_num, cur_nr_sectors); 427 if (n1 > 0) { 428 BLKDBG_EVENT(bs->file, BLKDBG_READ_BACKING_AIO); 429 qemu_co_mutex_unlock(&s->lock); 430 ret = bdrv_co_readv(bs->backing_hd, sector_num, 431 n1, &hd_qiov); 432 qemu_co_mutex_lock(&s->lock); 433 if (ret < 0) { 434 goto fail; 435 } 436 } 437 } else { 438 /* Note: in this case, no need to wait */ 439 qemu_iovec_memset(&hd_qiov, 0, 512 * cur_nr_sectors); 440 } 441 } else if (cluster_offset & QCOW_OFLAG_COMPRESSED) { 442 /* add AIO support for compressed blocks ? */ 443 ret = qcow2_decompress_cluster(bs, cluster_offset); 444 if (ret < 0) { 445 goto fail; 446 } 447 448 qemu_iovec_from_buffer(&hd_qiov, 449 s->cluster_cache + index_in_cluster * 512, 450 512 * cur_nr_sectors); 451 } else { 452 if ((cluster_offset & 511) != 0) { 453 ret = -EIO; 454 goto fail; 455 } 456 457 if (s->crypt_method) { 458 /* 459 * For encrypted images, read everything into a temporary 460 * contiguous buffer on which the AES functions can work. 461 */ 462 if (!cluster_data) { 463 cluster_data = 464 qemu_blockalign(bs, QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size); 465 } 466 467 assert(cur_nr_sectors <= 468 QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors); 469 qemu_iovec_reset(&hd_qiov); 470 qemu_iovec_add(&hd_qiov, cluster_data, 471 512 * cur_nr_sectors); 472 } 473 474 BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO); 475 qemu_co_mutex_unlock(&s->lock); 476 ret = bdrv_co_readv(bs->file, 477 (cluster_offset >> 9) + index_in_cluster, 478 cur_nr_sectors, &hd_qiov); 479 qemu_co_mutex_lock(&s->lock); 480 if (ret < 0) { 481 goto fail; 482 } 483 if (s->crypt_method) { 484 qcow2_encrypt_sectors(s, sector_num, cluster_data, 485 cluster_data, cur_nr_sectors, 0, &s->aes_decrypt_key); 486 qemu_iovec_reset(&hd_qiov); 487 qemu_iovec_copy(&hd_qiov, qiov, bytes_done, 488 cur_nr_sectors * 512); 489 qemu_iovec_from_buffer(&hd_qiov, cluster_data, 490 512 * cur_nr_sectors); 491 } 492 } 493 494 remaining_sectors -= cur_nr_sectors; 495 sector_num += cur_nr_sectors; 496 bytes_done += cur_nr_sectors * 512; 497 } 498 ret = 0; 499 500 fail: 501 qemu_co_mutex_unlock(&s->lock); 502 503 qemu_iovec_destroy(&hd_qiov); 504 qemu_vfree(cluster_data); 505 506 return ret; 507 } 508 509 static void run_dependent_requests(BDRVQcowState *s, QCowL2Meta *m) 510 { 511 /* Take the request off the list of running requests */ 512 if (m->nb_clusters != 0) { 513 QLIST_REMOVE(m, next_in_flight); 514 } 515 516 /* Restart all dependent requests */ 517 if (!qemu_co_queue_empty(&m->dependent_requests)) { 518 qemu_co_mutex_unlock(&s->lock); 519 qemu_co_queue_restart_all(&m->dependent_requests); 520 qemu_co_mutex_lock(&s->lock); 521 } 522 } 523 524 static coroutine_fn int qcow2_co_writev(BlockDriverState *bs, 525 int64_t sector_num, 526 int remaining_sectors, 527 QEMUIOVector *qiov) 528 { 529 BDRVQcowState *s = bs->opaque; 530 int index_in_cluster; 531 int n_end; 532 int ret; 533 int cur_nr_sectors; /* number of sectors in current iteration */ 534 uint64_t cluster_offset; 535 QEMUIOVector hd_qiov; 536 uint64_t bytes_done = 0; 537 uint8_t *cluster_data = NULL; 538 QCowL2Meta l2meta = { 539 .nb_clusters = 0, 540 }; 541 542 qemu_co_queue_init(&l2meta.dependent_requests); 543 544 qemu_iovec_init(&hd_qiov, qiov->niov); 545 546 s->cluster_cache_offset = -1; /* disable compressed cache */ 547 548 qemu_co_mutex_lock(&s->lock); 549 550 while (remaining_sectors != 0) { 551 552 index_in_cluster = sector_num & (s->cluster_sectors - 1); 553 n_end = index_in_cluster + remaining_sectors; 554 if (s->crypt_method && 555 n_end > QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors) { 556 n_end = QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors; 557 } 558 559 ret = qcow2_alloc_cluster_offset(bs, sector_num << 9, 560 index_in_cluster, n_end, &cur_nr_sectors, &l2meta); 561 if (ret < 0) { 562 goto fail; 563 } 564 565 cluster_offset = l2meta.cluster_offset; 566 assert((cluster_offset & 511) == 0); 567 568 qemu_iovec_reset(&hd_qiov); 569 qemu_iovec_copy(&hd_qiov, qiov, bytes_done, 570 cur_nr_sectors * 512); 571 572 if (s->crypt_method) { 573 if (!cluster_data) { 574 cluster_data = qemu_blockalign(bs, QCOW_MAX_CRYPT_CLUSTERS * 575 s->cluster_size); 576 } 577 578 assert(hd_qiov.size <= 579 QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size); 580 qemu_iovec_to_buffer(&hd_qiov, cluster_data); 581 582 qcow2_encrypt_sectors(s, sector_num, cluster_data, 583 cluster_data, cur_nr_sectors, 1, &s->aes_encrypt_key); 584 585 qemu_iovec_reset(&hd_qiov); 586 qemu_iovec_add(&hd_qiov, cluster_data, 587 cur_nr_sectors * 512); 588 } 589 590 BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO); 591 qemu_co_mutex_unlock(&s->lock); 592 ret = bdrv_co_writev(bs->file, 593 (cluster_offset >> 9) + index_in_cluster, 594 cur_nr_sectors, &hd_qiov); 595 qemu_co_mutex_lock(&s->lock); 596 if (ret < 0) { 597 goto fail; 598 } 599 600 ret = qcow2_alloc_cluster_link_l2(bs, &l2meta); 601 if (ret < 0) { 602 goto fail; 603 } 604 605 run_dependent_requests(s, &l2meta); 606 607 remaining_sectors -= cur_nr_sectors; 608 sector_num += cur_nr_sectors; 609 bytes_done += cur_nr_sectors * 512; 610 } 611 ret = 0; 612 613 fail: 614 run_dependent_requests(s, &l2meta); 615 616 qemu_co_mutex_unlock(&s->lock); 617 618 qemu_iovec_destroy(&hd_qiov); 619 qemu_vfree(cluster_data); 620 621 return ret; 622 } 623 624 static void qcow2_close(BlockDriverState *bs) 625 { 626 BDRVQcowState *s = bs->opaque; 627 g_free(s->l1_table); 628 629 qcow2_cache_flush(bs, s->l2_table_cache); 630 qcow2_cache_flush(bs, s->refcount_block_cache); 631 632 qcow2_cache_destroy(bs, s->l2_table_cache); 633 qcow2_cache_destroy(bs, s->refcount_block_cache); 634 635 g_free(s->cluster_cache); 636 qemu_vfree(s->cluster_data); 637 qcow2_refcount_close(bs); 638 qcow2_free_snapshots(bs); 639 } 640 641 static void qcow2_invalidate_cache(BlockDriverState *bs) 642 { 643 BDRVQcowState *s = bs->opaque; 644 int flags = s->flags; 645 AES_KEY aes_encrypt_key; 646 AES_KEY aes_decrypt_key; 647 uint32_t crypt_method = 0; 648 649 /* 650 * Backing files are read-only which makes all of their metadata immutable, 651 * that means we don't have to worry about reopening them here. 652 */ 653 654 if (s->crypt_method) { 655 crypt_method = s->crypt_method; 656 memcpy(&aes_encrypt_key, &s->aes_encrypt_key, sizeof(aes_encrypt_key)); 657 memcpy(&aes_decrypt_key, &s->aes_decrypt_key, sizeof(aes_decrypt_key)); 658 } 659 660 qcow2_close(bs); 661 662 memset(s, 0, sizeof(BDRVQcowState)); 663 qcow2_open(bs, flags); 664 665 if (crypt_method) { 666 s->crypt_method = crypt_method; 667 memcpy(&s->aes_encrypt_key, &aes_encrypt_key, sizeof(aes_encrypt_key)); 668 memcpy(&s->aes_decrypt_key, &aes_decrypt_key, sizeof(aes_decrypt_key)); 669 } 670 } 671 672 /* 673 * Updates the variable length parts of the qcow2 header, i.e. the backing file 674 * name and all extensions. qcow2 was not designed to allow such changes, so if 675 * we run out of space (we can only use the first cluster) this function may 676 * fail. 677 * 678 * Returns 0 on success, -errno in error cases. 679 */ 680 static int qcow2_update_ext_header(BlockDriverState *bs, 681 const char *backing_file, const char *backing_fmt) 682 { 683 size_t backing_file_len = 0; 684 size_t backing_fmt_len = 0; 685 BDRVQcowState *s = bs->opaque; 686 QCowExtension ext_backing_fmt = {0, 0}; 687 int ret; 688 689 /* Backing file format doesn't make sense without a backing file */ 690 if (backing_fmt && !backing_file) { 691 return -EINVAL; 692 } 693 694 /* Prepare the backing file format extension if needed */ 695 if (backing_fmt) { 696 ext_backing_fmt.len = cpu_to_be32(strlen(backing_fmt)); 697 ext_backing_fmt.magic = cpu_to_be32(QCOW2_EXT_MAGIC_BACKING_FORMAT); 698 backing_fmt_len = ((sizeof(ext_backing_fmt) 699 + strlen(backing_fmt) + 7) & ~7); 700 } 701 702 /* Check if we can fit the new header into the first cluster */ 703 if (backing_file) { 704 backing_file_len = strlen(backing_file); 705 } 706 707 size_t header_size = sizeof(QCowHeader) + backing_file_len 708 + backing_fmt_len; 709 710 if (header_size > s->cluster_size) { 711 return -ENOSPC; 712 } 713 714 /* Rewrite backing file name and qcow2 extensions */ 715 size_t ext_size = header_size - sizeof(QCowHeader); 716 uint8_t buf[ext_size]; 717 size_t offset = 0; 718 size_t backing_file_offset = 0; 719 720 if (backing_file) { 721 if (backing_fmt) { 722 int padding = backing_fmt_len - 723 (sizeof(ext_backing_fmt) + strlen(backing_fmt)); 724 725 memcpy(buf + offset, &ext_backing_fmt, sizeof(ext_backing_fmt)); 726 offset += sizeof(ext_backing_fmt); 727 728 memcpy(buf + offset, backing_fmt, strlen(backing_fmt)); 729 offset += strlen(backing_fmt); 730 731 memset(buf + offset, 0, padding); 732 offset += padding; 733 } 734 735 memcpy(buf + offset, backing_file, backing_file_len); 736 backing_file_offset = sizeof(QCowHeader) + offset; 737 } 738 739 ret = bdrv_pwrite_sync(bs->file, sizeof(QCowHeader), buf, ext_size); 740 if (ret < 0) { 741 goto fail; 742 } 743 744 /* Update header fields */ 745 uint64_t be_backing_file_offset = cpu_to_be64(backing_file_offset); 746 uint32_t be_backing_file_size = cpu_to_be32(backing_file_len); 747 748 ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, backing_file_offset), 749 &be_backing_file_offset, sizeof(uint64_t)); 750 if (ret < 0) { 751 goto fail; 752 } 753 754 ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, backing_file_size), 755 &be_backing_file_size, sizeof(uint32_t)); 756 if (ret < 0) { 757 goto fail; 758 } 759 760 ret = 0; 761 fail: 762 return ret; 763 } 764 765 static int qcow2_change_backing_file(BlockDriverState *bs, 766 const char *backing_file, const char *backing_fmt) 767 { 768 return qcow2_update_ext_header(bs, backing_file, backing_fmt); 769 } 770 771 static int preallocate(BlockDriverState *bs) 772 { 773 uint64_t nb_sectors; 774 uint64_t offset; 775 int num; 776 int ret; 777 QCowL2Meta meta; 778 779 nb_sectors = bdrv_getlength(bs) >> 9; 780 offset = 0; 781 qemu_co_queue_init(&meta.dependent_requests); 782 meta.cluster_offset = 0; 783 784 while (nb_sectors) { 785 num = MIN(nb_sectors, INT_MAX >> 9); 786 ret = qcow2_alloc_cluster_offset(bs, offset, 0, num, &num, &meta); 787 if (ret < 0) { 788 return ret; 789 } 790 791 ret = qcow2_alloc_cluster_link_l2(bs, &meta); 792 if (ret < 0) { 793 qcow2_free_any_clusters(bs, meta.cluster_offset, meta.nb_clusters); 794 return ret; 795 } 796 797 /* There are no dependent requests, but we need to remove our request 798 * from the list of in-flight requests */ 799 run_dependent_requests(bs->opaque, &meta); 800 801 /* TODO Preallocate data if requested */ 802 803 nb_sectors -= num; 804 offset += num << 9; 805 } 806 807 /* 808 * It is expected that the image file is large enough to actually contain 809 * all of the allocated clusters (otherwise we get failing reads after 810 * EOF). Extend the image to the last allocated sector. 811 */ 812 if (meta.cluster_offset != 0) { 813 uint8_t buf[512]; 814 memset(buf, 0, 512); 815 ret = bdrv_write(bs->file, (meta.cluster_offset >> 9) + num - 1, buf, 1); 816 if (ret < 0) { 817 return ret; 818 } 819 } 820 821 return 0; 822 } 823 824 static int qcow2_create2(const char *filename, int64_t total_size, 825 const char *backing_file, const char *backing_format, 826 int flags, size_t cluster_size, int prealloc, 827 QEMUOptionParameter *options) 828 { 829 /* Calculate cluster_bits */ 830 int cluster_bits; 831 cluster_bits = ffs(cluster_size) - 1; 832 if (cluster_bits < MIN_CLUSTER_BITS || cluster_bits > MAX_CLUSTER_BITS || 833 (1 << cluster_bits) != cluster_size) 834 { 835 error_report( 836 "Cluster size must be a power of two between %d and %dk", 837 1 << MIN_CLUSTER_BITS, 1 << (MAX_CLUSTER_BITS - 10)); 838 return -EINVAL; 839 } 840 841 /* 842 * Open the image file and write a minimal qcow2 header. 843 * 844 * We keep things simple and start with a zero-sized image. We also 845 * do without refcount blocks or a L1 table for now. We'll fix the 846 * inconsistency later. 847 * 848 * We do need a refcount table because growing the refcount table means 849 * allocating two new refcount blocks - the seconds of which would be at 850 * 2 GB for 64k clusters, and we don't want to have a 2 GB initial file 851 * size for any qcow2 image. 852 */ 853 BlockDriverState* bs; 854 QCowHeader header; 855 uint8_t* refcount_table; 856 int ret; 857 858 ret = bdrv_create_file(filename, options); 859 if (ret < 0) { 860 return ret; 861 } 862 863 ret = bdrv_file_open(&bs, filename, BDRV_O_RDWR); 864 if (ret < 0) { 865 return ret; 866 } 867 868 /* Write the header */ 869 memset(&header, 0, sizeof(header)); 870 header.magic = cpu_to_be32(QCOW_MAGIC); 871 header.version = cpu_to_be32(QCOW_VERSION); 872 header.cluster_bits = cpu_to_be32(cluster_bits); 873 header.size = cpu_to_be64(0); 874 header.l1_table_offset = cpu_to_be64(0); 875 header.l1_size = cpu_to_be32(0); 876 header.refcount_table_offset = cpu_to_be64(cluster_size); 877 header.refcount_table_clusters = cpu_to_be32(1); 878 879 if (flags & BLOCK_FLAG_ENCRYPT) { 880 header.crypt_method = cpu_to_be32(QCOW_CRYPT_AES); 881 } else { 882 header.crypt_method = cpu_to_be32(QCOW_CRYPT_NONE); 883 } 884 885 ret = bdrv_pwrite(bs, 0, &header, sizeof(header)); 886 if (ret < 0) { 887 goto out; 888 } 889 890 /* Write an empty refcount table */ 891 refcount_table = g_malloc0(cluster_size); 892 ret = bdrv_pwrite(bs, cluster_size, refcount_table, cluster_size); 893 g_free(refcount_table); 894 895 if (ret < 0) { 896 goto out; 897 } 898 899 bdrv_close(bs); 900 901 /* 902 * And now open the image and make it consistent first (i.e. increase the 903 * refcount of the cluster that is occupied by the header and the refcount 904 * table) 905 */ 906 BlockDriver* drv = bdrv_find_format("qcow2"); 907 assert(drv != NULL); 908 ret = bdrv_open(bs, filename, 909 BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_NO_FLUSH, drv); 910 if (ret < 0) { 911 goto out; 912 } 913 914 ret = qcow2_alloc_clusters(bs, 2 * cluster_size); 915 if (ret < 0) { 916 goto out; 917 918 } else if (ret != 0) { 919 error_report("Huh, first cluster in empty image is already in use?"); 920 abort(); 921 } 922 923 /* Okay, now that we have a valid image, let's give it the right size */ 924 ret = bdrv_truncate(bs, total_size * BDRV_SECTOR_SIZE); 925 if (ret < 0) { 926 goto out; 927 } 928 929 /* Want a backing file? There you go.*/ 930 if (backing_file) { 931 ret = bdrv_change_backing_file(bs, backing_file, backing_format); 932 if (ret < 0) { 933 goto out; 934 } 935 } 936 937 /* And if we're supposed to preallocate metadata, do that now */ 938 if (prealloc) { 939 ret = preallocate(bs); 940 if (ret < 0) { 941 goto out; 942 } 943 } 944 945 ret = 0; 946 out: 947 bdrv_delete(bs); 948 return ret; 949 } 950 951 static int qcow2_create(const char *filename, QEMUOptionParameter *options) 952 { 953 const char *backing_file = NULL; 954 const char *backing_fmt = NULL; 955 uint64_t sectors = 0; 956 int flags = 0; 957 size_t cluster_size = DEFAULT_CLUSTER_SIZE; 958 int prealloc = 0; 959 960 /* Read out options */ 961 while (options && options->name) { 962 if (!strcmp(options->name, BLOCK_OPT_SIZE)) { 963 sectors = options->value.n / 512; 964 } else if (!strcmp(options->name, BLOCK_OPT_BACKING_FILE)) { 965 backing_file = options->value.s; 966 } else if (!strcmp(options->name, BLOCK_OPT_BACKING_FMT)) { 967 backing_fmt = options->value.s; 968 } else if (!strcmp(options->name, BLOCK_OPT_ENCRYPT)) { 969 flags |= options->value.n ? BLOCK_FLAG_ENCRYPT : 0; 970 } else if (!strcmp(options->name, BLOCK_OPT_CLUSTER_SIZE)) { 971 if (options->value.n) { 972 cluster_size = options->value.n; 973 } 974 } else if (!strcmp(options->name, BLOCK_OPT_PREALLOC)) { 975 if (!options->value.s || !strcmp(options->value.s, "off")) { 976 prealloc = 0; 977 } else if (!strcmp(options->value.s, "metadata")) { 978 prealloc = 1; 979 } else { 980 fprintf(stderr, "Invalid preallocation mode: '%s'\n", 981 options->value.s); 982 return -EINVAL; 983 } 984 } 985 options++; 986 } 987 988 if (backing_file && prealloc) { 989 fprintf(stderr, "Backing file and preallocation cannot be used at " 990 "the same time\n"); 991 return -EINVAL; 992 } 993 994 return qcow2_create2(filename, sectors, backing_file, backing_fmt, flags, 995 cluster_size, prealloc, options); 996 } 997 998 static int qcow2_make_empty(BlockDriverState *bs) 999 { 1000 #if 0 1001 /* XXX: not correct */ 1002 BDRVQcowState *s = bs->opaque; 1003 uint32_t l1_length = s->l1_size * sizeof(uint64_t); 1004 int ret; 1005 1006 memset(s->l1_table, 0, l1_length); 1007 if (bdrv_pwrite(bs->file, s->l1_table_offset, s->l1_table, l1_length) < 0) 1008 return -1; 1009 ret = bdrv_truncate(bs->file, s->l1_table_offset + l1_length); 1010 if (ret < 0) 1011 return ret; 1012 1013 l2_cache_reset(bs); 1014 #endif 1015 return 0; 1016 } 1017 1018 static coroutine_fn int qcow2_co_discard(BlockDriverState *bs, 1019 int64_t sector_num, int nb_sectors) 1020 { 1021 int ret; 1022 BDRVQcowState *s = bs->opaque; 1023 1024 qemu_co_mutex_lock(&s->lock); 1025 ret = qcow2_discard_clusters(bs, sector_num << BDRV_SECTOR_BITS, 1026 nb_sectors); 1027 qemu_co_mutex_unlock(&s->lock); 1028 return ret; 1029 } 1030 1031 static int qcow2_truncate(BlockDriverState *bs, int64_t offset) 1032 { 1033 BDRVQcowState *s = bs->opaque; 1034 int ret, new_l1_size; 1035 1036 if (offset & 511) { 1037 return -EINVAL; 1038 } 1039 1040 /* cannot proceed if image has snapshots */ 1041 if (s->nb_snapshots) { 1042 return -ENOTSUP; 1043 } 1044 1045 /* shrinking is currently not supported */ 1046 if (offset < bs->total_sectors * 512) { 1047 return -ENOTSUP; 1048 } 1049 1050 new_l1_size = size_to_l1(s, offset); 1051 ret = qcow2_grow_l1_table(bs, new_l1_size, true); 1052 if (ret < 0) { 1053 return ret; 1054 } 1055 1056 /* write updated header.size */ 1057 offset = cpu_to_be64(offset); 1058 ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, size), 1059 &offset, sizeof(uint64_t)); 1060 if (ret < 0) { 1061 return ret; 1062 } 1063 1064 s->l1_vm_state_index = new_l1_size; 1065 return 0; 1066 } 1067 1068 /* XXX: put compressed sectors first, then all the cluster aligned 1069 tables to avoid losing bytes in alignment */ 1070 static int qcow2_write_compressed(BlockDriverState *bs, int64_t sector_num, 1071 const uint8_t *buf, int nb_sectors) 1072 { 1073 BDRVQcowState *s = bs->opaque; 1074 z_stream strm; 1075 int ret, out_len; 1076 uint8_t *out_buf; 1077 uint64_t cluster_offset; 1078 1079 if (nb_sectors == 0) { 1080 /* align end of file to a sector boundary to ease reading with 1081 sector based I/Os */ 1082 cluster_offset = bdrv_getlength(bs->file); 1083 cluster_offset = (cluster_offset + 511) & ~511; 1084 bdrv_truncate(bs->file, cluster_offset); 1085 return 0; 1086 } 1087 1088 if (nb_sectors != s->cluster_sectors) 1089 return -EINVAL; 1090 1091 out_buf = g_malloc(s->cluster_size + (s->cluster_size / 1000) + 128); 1092 1093 /* best compression, small window, no zlib header */ 1094 memset(&strm, 0, sizeof(strm)); 1095 ret = deflateInit2(&strm, Z_DEFAULT_COMPRESSION, 1096 Z_DEFLATED, -12, 1097 9, Z_DEFAULT_STRATEGY); 1098 if (ret != 0) { 1099 ret = -EINVAL; 1100 goto fail; 1101 } 1102 1103 strm.avail_in = s->cluster_size; 1104 strm.next_in = (uint8_t *)buf; 1105 strm.avail_out = s->cluster_size; 1106 strm.next_out = out_buf; 1107 1108 ret = deflate(&strm, Z_FINISH); 1109 if (ret != Z_STREAM_END && ret != Z_OK) { 1110 deflateEnd(&strm); 1111 ret = -EINVAL; 1112 goto fail; 1113 } 1114 out_len = strm.next_out - out_buf; 1115 1116 deflateEnd(&strm); 1117 1118 if (ret != Z_STREAM_END || out_len >= s->cluster_size) { 1119 /* could not compress: write normal cluster */ 1120 ret = bdrv_write(bs, sector_num, buf, s->cluster_sectors); 1121 if (ret < 0) { 1122 goto fail; 1123 } 1124 } else { 1125 cluster_offset = qcow2_alloc_compressed_cluster_offset(bs, 1126 sector_num << 9, out_len); 1127 if (!cluster_offset) { 1128 ret = -EIO; 1129 goto fail; 1130 } 1131 cluster_offset &= s->cluster_offset_mask; 1132 BLKDBG_EVENT(bs->file, BLKDBG_WRITE_COMPRESSED); 1133 ret = bdrv_pwrite(bs->file, cluster_offset, out_buf, out_len); 1134 if (ret < 0) { 1135 goto fail; 1136 } 1137 } 1138 1139 ret = 0; 1140 fail: 1141 g_free(out_buf); 1142 return ret; 1143 } 1144 1145 static coroutine_fn int qcow2_co_flush_to_os(BlockDriverState *bs) 1146 { 1147 BDRVQcowState *s = bs->opaque; 1148 int ret; 1149 1150 qemu_co_mutex_lock(&s->lock); 1151 ret = qcow2_cache_flush(bs, s->l2_table_cache); 1152 if (ret < 0) { 1153 qemu_co_mutex_unlock(&s->lock); 1154 return ret; 1155 } 1156 1157 ret = qcow2_cache_flush(bs, s->refcount_block_cache); 1158 if (ret < 0) { 1159 qemu_co_mutex_unlock(&s->lock); 1160 return ret; 1161 } 1162 qemu_co_mutex_unlock(&s->lock); 1163 1164 return 0; 1165 } 1166 1167 static coroutine_fn int qcow2_co_flush_to_disk(BlockDriverState *bs) 1168 { 1169 return bdrv_co_flush(bs->file); 1170 } 1171 1172 static int64_t qcow2_vm_state_offset(BDRVQcowState *s) 1173 { 1174 return (int64_t)s->l1_vm_state_index << (s->cluster_bits + s->l2_bits); 1175 } 1176 1177 static int qcow2_get_info(BlockDriverState *bs, BlockDriverInfo *bdi) 1178 { 1179 BDRVQcowState *s = bs->opaque; 1180 bdi->cluster_size = s->cluster_size; 1181 bdi->vm_state_offset = qcow2_vm_state_offset(s); 1182 return 0; 1183 } 1184 1185 1186 static int qcow2_check(BlockDriverState *bs, BdrvCheckResult *result) 1187 { 1188 return qcow2_check_refcounts(bs, result); 1189 } 1190 1191 #if 0 1192 static void dump_refcounts(BlockDriverState *bs) 1193 { 1194 BDRVQcowState *s = bs->opaque; 1195 int64_t nb_clusters, k, k1, size; 1196 int refcount; 1197 1198 size = bdrv_getlength(bs->file); 1199 nb_clusters = size_to_clusters(s, size); 1200 for(k = 0; k < nb_clusters;) { 1201 k1 = k; 1202 refcount = get_refcount(bs, k); 1203 k++; 1204 while (k < nb_clusters && get_refcount(bs, k) == refcount) 1205 k++; 1206 printf("%" PRId64 ": refcount=%d nb=%" PRId64 "\n", k, refcount, 1207 k - k1); 1208 } 1209 } 1210 #endif 1211 1212 static int qcow2_save_vmstate(BlockDriverState *bs, const uint8_t *buf, 1213 int64_t pos, int size) 1214 { 1215 BDRVQcowState *s = bs->opaque; 1216 int growable = bs->growable; 1217 int ret; 1218 1219 BLKDBG_EVENT(bs->file, BLKDBG_VMSTATE_SAVE); 1220 bs->growable = 1; 1221 ret = bdrv_pwrite(bs, qcow2_vm_state_offset(s) + pos, buf, size); 1222 bs->growable = growable; 1223 1224 return ret; 1225 } 1226 1227 static int qcow2_load_vmstate(BlockDriverState *bs, uint8_t *buf, 1228 int64_t pos, int size) 1229 { 1230 BDRVQcowState *s = bs->opaque; 1231 int growable = bs->growable; 1232 int ret; 1233 1234 BLKDBG_EVENT(bs->file, BLKDBG_VMSTATE_LOAD); 1235 bs->growable = 1; 1236 ret = bdrv_pread(bs, qcow2_vm_state_offset(s) + pos, buf, size); 1237 bs->growable = growable; 1238 1239 return ret; 1240 } 1241 1242 static QEMUOptionParameter qcow2_create_options[] = { 1243 { 1244 .name = BLOCK_OPT_SIZE, 1245 .type = OPT_SIZE, 1246 .help = "Virtual disk size" 1247 }, 1248 { 1249 .name = BLOCK_OPT_BACKING_FILE, 1250 .type = OPT_STRING, 1251 .help = "File name of a base image" 1252 }, 1253 { 1254 .name = BLOCK_OPT_BACKING_FMT, 1255 .type = OPT_STRING, 1256 .help = "Image format of the base image" 1257 }, 1258 { 1259 .name = BLOCK_OPT_ENCRYPT, 1260 .type = OPT_FLAG, 1261 .help = "Encrypt the image" 1262 }, 1263 { 1264 .name = BLOCK_OPT_CLUSTER_SIZE, 1265 .type = OPT_SIZE, 1266 .help = "qcow2 cluster size", 1267 .value = { .n = DEFAULT_CLUSTER_SIZE }, 1268 }, 1269 { 1270 .name = BLOCK_OPT_PREALLOC, 1271 .type = OPT_STRING, 1272 .help = "Preallocation mode (allowed values: off, metadata)" 1273 }, 1274 { NULL } 1275 }; 1276 1277 static BlockDriver bdrv_qcow2 = { 1278 .format_name = "qcow2", 1279 .instance_size = sizeof(BDRVQcowState), 1280 .bdrv_probe = qcow2_probe, 1281 .bdrv_open = qcow2_open, 1282 .bdrv_close = qcow2_close, 1283 .bdrv_create = qcow2_create, 1284 .bdrv_co_is_allocated = qcow2_co_is_allocated, 1285 .bdrv_set_key = qcow2_set_key, 1286 .bdrv_make_empty = qcow2_make_empty, 1287 1288 .bdrv_co_readv = qcow2_co_readv, 1289 .bdrv_co_writev = qcow2_co_writev, 1290 .bdrv_co_flush_to_os = qcow2_co_flush_to_os, 1291 .bdrv_co_flush_to_disk = qcow2_co_flush_to_disk, 1292 1293 .bdrv_co_discard = qcow2_co_discard, 1294 .bdrv_truncate = qcow2_truncate, 1295 .bdrv_write_compressed = qcow2_write_compressed, 1296 1297 .bdrv_snapshot_create = qcow2_snapshot_create, 1298 .bdrv_snapshot_goto = qcow2_snapshot_goto, 1299 .bdrv_snapshot_delete = qcow2_snapshot_delete, 1300 .bdrv_snapshot_list = qcow2_snapshot_list, 1301 .bdrv_snapshot_load_tmp = qcow2_snapshot_load_tmp, 1302 .bdrv_get_info = qcow2_get_info, 1303 1304 .bdrv_save_vmstate = qcow2_save_vmstate, 1305 .bdrv_load_vmstate = qcow2_load_vmstate, 1306 1307 .bdrv_change_backing_file = qcow2_change_backing_file, 1308 1309 .bdrv_invalidate_cache = qcow2_invalidate_cache, 1310 1311 .create_options = qcow2_create_options, 1312 .bdrv_check = qcow2_check, 1313 }; 1314 1315 static void bdrv_qcow2_init(void) 1316 { 1317 bdrv_register(&bdrv_qcow2); 1318 } 1319 1320 block_init(bdrv_qcow2_init); 1321