1 /* 2 * Block driver for the QCOW version 2 format 3 * 4 * Copyright (c) 2004-2006 Fabrice Bellard 5 * 6 * Permission is hereby granted, free of charge, to any person obtaining a copy 7 * of this software and associated documentation files (the "Software"), to deal 8 * in the Software without restriction, including without limitation the rights 9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 10 * copies of the Software, and to permit persons to whom the Software is 11 * furnished to do so, subject to the following conditions: 12 * 13 * The above copyright notice and this permission notice shall be included in 14 * all copies or substantial portions of the Software. 15 * 16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 22 * THE SOFTWARE. 23 */ 24 25 #include <zlib.h> 26 27 #include "qemu-common.h" 28 #include "block_int.h" 29 #include "block/qcow2.h" 30 31 int qcow2_grow_l1_table(BlockDriverState *bs, int min_size, bool exact_size) 32 { 33 BDRVQcowState *s = bs->opaque; 34 int new_l1_size, new_l1_size2, ret, i; 35 uint64_t *new_l1_table; 36 int64_t new_l1_table_offset; 37 uint8_t data[12]; 38 39 if (min_size <= s->l1_size) 40 return 0; 41 42 if (exact_size) { 43 new_l1_size = min_size; 44 } else { 45 /* Bump size up to reduce the number of times we have to grow */ 46 new_l1_size = s->l1_size; 47 if (new_l1_size == 0) { 48 new_l1_size = 1; 49 } 50 while (min_size > new_l1_size) { 51 new_l1_size = (new_l1_size * 3 + 1) / 2; 52 } 53 } 54 55 #ifdef DEBUG_ALLOC2 56 printf("grow l1_table from %d to %d\n", s->l1_size, new_l1_size); 57 #endif 58 59 new_l1_size2 = sizeof(uint64_t) * new_l1_size; 60 new_l1_table = g_malloc0(align_offset(new_l1_size2, 512)); 61 memcpy(new_l1_table, s->l1_table, s->l1_size * sizeof(uint64_t)); 62 63 /* write new table (align to cluster) */ 64 BLKDBG_EVENT(bs->file, BLKDBG_L1_GROW_ALLOC_TABLE); 65 new_l1_table_offset = qcow2_alloc_clusters(bs, new_l1_size2); 66 if (new_l1_table_offset < 0) { 67 g_free(new_l1_table); 68 return new_l1_table_offset; 69 } 70 71 ret = qcow2_cache_flush(bs, s->refcount_block_cache); 72 if (ret < 0) { 73 goto fail; 74 } 75 76 BLKDBG_EVENT(bs->file, BLKDBG_L1_GROW_WRITE_TABLE); 77 for(i = 0; i < s->l1_size; i++) 78 new_l1_table[i] = cpu_to_be64(new_l1_table[i]); 79 ret = bdrv_pwrite_sync(bs->file, new_l1_table_offset, new_l1_table, new_l1_size2); 80 if (ret < 0) 81 goto fail; 82 for(i = 0; i < s->l1_size; i++) 83 new_l1_table[i] = be64_to_cpu(new_l1_table[i]); 84 85 /* set new table */ 86 BLKDBG_EVENT(bs->file, BLKDBG_L1_GROW_ACTIVATE_TABLE); 87 cpu_to_be32w((uint32_t*)data, new_l1_size); 88 cpu_to_be64wu((uint64_t*)(data + 4), new_l1_table_offset); 89 ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, l1_size), data,sizeof(data)); 90 if (ret < 0) { 91 goto fail; 92 } 93 g_free(s->l1_table); 94 qcow2_free_clusters(bs, s->l1_table_offset, s->l1_size * sizeof(uint64_t)); 95 s->l1_table_offset = new_l1_table_offset; 96 s->l1_table = new_l1_table; 97 s->l1_size = new_l1_size; 98 return 0; 99 fail: 100 g_free(new_l1_table); 101 qcow2_free_clusters(bs, new_l1_table_offset, new_l1_size2); 102 return ret; 103 } 104 105 /* 106 * l2_load 107 * 108 * Loads a L2 table into memory. If the table is in the cache, the cache 109 * is used; otherwise the L2 table is loaded from the image file. 110 * 111 * Returns a pointer to the L2 table on success, or NULL if the read from 112 * the image file failed. 113 */ 114 115 static int l2_load(BlockDriverState *bs, uint64_t l2_offset, 116 uint64_t **l2_table) 117 { 118 BDRVQcowState *s = bs->opaque; 119 int ret; 120 121 ret = qcow2_cache_get(bs, s->l2_table_cache, l2_offset, (void**) l2_table); 122 123 return ret; 124 } 125 126 /* 127 * Writes one sector of the L1 table to the disk (can't update single entries 128 * and we really don't want bdrv_pread to perform a read-modify-write) 129 */ 130 #define L1_ENTRIES_PER_SECTOR (512 / 8) 131 static int write_l1_entry(BlockDriverState *bs, int l1_index) 132 { 133 BDRVQcowState *s = bs->opaque; 134 uint64_t buf[L1_ENTRIES_PER_SECTOR]; 135 int l1_start_index; 136 int i, ret; 137 138 l1_start_index = l1_index & ~(L1_ENTRIES_PER_SECTOR - 1); 139 for (i = 0; i < L1_ENTRIES_PER_SECTOR; i++) { 140 buf[i] = cpu_to_be64(s->l1_table[l1_start_index + i]); 141 } 142 143 BLKDBG_EVENT(bs->file, BLKDBG_L1_UPDATE); 144 ret = bdrv_pwrite_sync(bs->file, s->l1_table_offset + 8 * l1_start_index, 145 buf, sizeof(buf)); 146 if (ret < 0) { 147 return ret; 148 } 149 150 return 0; 151 } 152 153 /* 154 * l2_allocate 155 * 156 * Allocate a new l2 entry in the file. If l1_index points to an already 157 * used entry in the L2 table (i.e. we are doing a copy on write for the L2 158 * table) copy the contents of the old L2 table into the newly allocated one. 159 * Otherwise the new table is initialized with zeros. 160 * 161 */ 162 163 static int l2_allocate(BlockDriverState *bs, int l1_index, uint64_t **table) 164 { 165 BDRVQcowState *s = bs->opaque; 166 uint64_t old_l2_offset; 167 uint64_t *l2_table; 168 int64_t l2_offset; 169 int ret; 170 171 old_l2_offset = s->l1_table[l1_index]; 172 173 /* allocate a new l2 entry */ 174 175 l2_offset = qcow2_alloc_clusters(bs, s->l2_size * sizeof(uint64_t)); 176 if (l2_offset < 0) { 177 return l2_offset; 178 } 179 180 ret = qcow2_cache_flush(bs, s->refcount_block_cache); 181 if (ret < 0) { 182 goto fail; 183 } 184 185 /* allocate a new entry in the l2 cache */ 186 187 ret = qcow2_cache_get_empty(bs, s->l2_table_cache, l2_offset, (void**) table); 188 if (ret < 0) { 189 return ret; 190 } 191 192 l2_table = *table; 193 194 if (old_l2_offset == 0) { 195 /* if there was no old l2 table, clear the new table */ 196 memset(l2_table, 0, s->l2_size * sizeof(uint64_t)); 197 } else { 198 uint64_t* old_table; 199 200 /* if there was an old l2 table, read it from the disk */ 201 BLKDBG_EVENT(bs->file, BLKDBG_L2_ALLOC_COW_READ); 202 ret = qcow2_cache_get(bs, s->l2_table_cache, old_l2_offset, 203 (void**) &old_table); 204 if (ret < 0) { 205 goto fail; 206 } 207 208 memcpy(l2_table, old_table, s->cluster_size); 209 210 ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &old_table); 211 if (ret < 0) { 212 goto fail; 213 } 214 } 215 216 /* write the l2 table to the file */ 217 BLKDBG_EVENT(bs->file, BLKDBG_L2_ALLOC_WRITE); 218 219 qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table); 220 ret = qcow2_cache_flush(bs, s->l2_table_cache); 221 if (ret < 0) { 222 goto fail; 223 } 224 225 /* update the L1 entry */ 226 s->l1_table[l1_index] = l2_offset | QCOW_OFLAG_COPIED; 227 ret = write_l1_entry(bs, l1_index); 228 if (ret < 0) { 229 goto fail; 230 } 231 232 *table = l2_table; 233 return 0; 234 235 fail: 236 qcow2_cache_put(bs, s->l2_table_cache, (void**) table); 237 s->l1_table[l1_index] = old_l2_offset; 238 return ret; 239 } 240 241 static int count_contiguous_clusters(uint64_t nb_clusters, int cluster_size, 242 uint64_t *l2_table, uint64_t start, uint64_t mask) 243 { 244 int i; 245 uint64_t offset = be64_to_cpu(l2_table[0]) & ~mask; 246 247 if (!offset) 248 return 0; 249 250 for (i = start; i < start + nb_clusters; i++) 251 if (offset + (uint64_t) i * cluster_size != (be64_to_cpu(l2_table[i]) & ~mask)) 252 break; 253 254 return (i - start); 255 } 256 257 static int count_contiguous_free_clusters(uint64_t nb_clusters, uint64_t *l2_table) 258 { 259 int i = 0; 260 261 while(nb_clusters-- && l2_table[i] == 0) 262 i++; 263 264 return i; 265 } 266 267 /* The crypt function is compatible with the linux cryptoloop 268 algorithm for < 4 GB images. NOTE: out_buf == in_buf is 269 supported */ 270 void qcow2_encrypt_sectors(BDRVQcowState *s, int64_t sector_num, 271 uint8_t *out_buf, const uint8_t *in_buf, 272 int nb_sectors, int enc, 273 const AES_KEY *key) 274 { 275 union { 276 uint64_t ll[2]; 277 uint8_t b[16]; 278 } ivec; 279 int i; 280 281 for(i = 0; i < nb_sectors; i++) { 282 ivec.ll[0] = cpu_to_le64(sector_num); 283 ivec.ll[1] = 0; 284 AES_cbc_encrypt(in_buf, out_buf, 512, key, 285 ivec.b, enc); 286 sector_num++; 287 in_buf += 512; 288 out_buf += 512; 289 } 290 } 291 292 293 static int qcow2_read(BlockDriverState *bs, int64_t sector_num, 294 uint8_t *buf, int nb_sectors) 295 { 296 BDRVQcowState *s = bs->opaque; 297 int ret, index_in_cluster, n, n1; 298 uint64_t cluster_offset; 299 struct iovec iov; 300 QEMUIOVector qiov; 301 302 while (nb_sectors > 0) { 303 n = nb_sectors; 304 305 ret = qcow2_get_cluster_offset(bs, sector_num << 9, &n, 306 &cluster_offset); 307 if (ret < 0) { 308 return ret; 309 } 310 311 index_in_cluster = sector_num & (s->cluster_sectors - 1); 312 if (!cluster_offset) { 313 if (bs->backing_hd) { 314 /* read from the base image */ 315 iov.iov_base = buf; 316 iov.iov_len = n * 512; 317 qemu_iovec_init_external(&qiov, &iov, 1); 318 319 n1 = qcow2_backing_read1(bs->backing_hd, &qiov, sector_num, n); 320 if (n1 > 0) { 321 BLKDBG_EVENT(bs->file, BLKDBG_READ_BACKING); 322 ret = bdrv_read(bs->backing_hd, sector_num, buf, n1); 323 if (ret < 0) 324 return -1; 325 } 326 } else { 327 memset(buf, 0, 512 * n); 328 } 329 } else if (cluster_offset & QCOW_OFLAG_COMPRESSED) { 330 if (qcow2_decompress_cluster(bs, cluster_offset) < 0) 331 return -1; 332 memcpy(buf, s->cluster_cache + index_in_cluster * 512, 512 * n); 333 } else { 334 BLKDBG_EVENT(bs->file, BLKDBG_READ); 335 ret = bdrv_pread(bs->file, cluster_offset + index_in_cluster * 512, buf, n * 512); 336 if (ret != n * 512) 337 return -1; 338 if (s->crypt_method) { 339 qcow2_encrypt_sectors(s, sector_num, buf, buf, n, 0, 340 &s->aes_decrypt_key); 341 } 342 } 343 nb_sectors -= n; 344 sector_num += n; 345 buf += n * 512; 346 } 347 return 0; 348 } 349 350 static int copy_sectors(BlockDriverState *bs, uint64_t start_sect, 351 uint64_t cluster_offset, int n_start, int n_end) 352 { 353 BDRVQcowState *s = bs->opaque; 354 int n, ret; 355 356 n = n_end - n_start; 357 if (n <= 0) 358 return 0; 359 BLKDBG_EVENT(bs->file, BLKDBG_COW_READ); 360 ret = qcow2_read(bs, start_sect + n_start, s->cluster_data, n); 361 if (ret < 0) 362 return ret; 363 if (s->crypt_method) { 364 qcow2_encrypt_sectors(s, start_sect + n_start, 365 s->cluster_data, 366 s->cluster_data, n, 1, 367 &s->aes_encrypt_key); 368 } 369 BLKDBG_EVENT(bs->file, BLKDBG_COW_WRITE); 370 ret = bdrv_write(bs->file, (cluster_offset >> 9) + n_start, 371 s->cluster_data, n); 372 if (ret < 0) 373 return ret; 374 return 0; 375 } 376 377 378 /* 379 * get_cluster_offset 380 * 381 * For a given offset of the disk image, find the cluster offset in 382 * qcow2 file. The offset is stored in *cluster_offset. 383 * 384 * on entry, *num is the number of contiguous clusters we'd like to 385 * access following offset. 386 * 387 * on exit, *num is the number of contiguous clusters we can read. 388 * 389 * Return 0, if the offset is found 390 * Return -errno, otherwise. 391 * 392 */ 393 394 int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset, 395 int *num, uint64_t *cluster_offset) 396 { 397 BDRVQcowState *s = bs->opaque; 398 unsigned int l1_index, l2_index; 399 uint64_t l2_offset, *l2_table; 400 int l1_bits, c; 401 unsigned int index_in_cluster, nb_clusters; 402 uint64_t nb_available, nb_needed; 403 int ret; 404 405 index_in_cluster = (offset >> 9) & (s->cluster_sectors - 1); 406 nb_needed = *num + index_in_cluster; 407 408 l1_bits = s->l2_bits + s->cluster_bits; 409 410 /* compute how many bytes there are between the offset and 411 * the end of the l1 entry 412 */ 413 414 nb_available = (1ULL << l1_bits) - (offset & ((1ULL << l1_bits) - 1)); 415 416 /* compute the number of available sectors */ 417 418 nb_available = (nb_available >> 9) + index_in_cluster; 419 420 if (nb_needed > nb_available) { 421 nb_needed = nb_available; 422 } 423 424 *cluster_offset = 0; 425 426 /* seek the the l2 offset in the l1 table */ 427 428 l1_index = offset >> l1_bits; 429 if (l1_index >= s->l1_size) 430 goto out; 431 432 l2_offset = s->l1_table[l1_index]; 433 434 /* seek the l2 table of the given l2 offset */ 435 436 if (!l2_offset) 437 goto out; 438 439 /* load the l2 table in memory */ 440 441 l2_offset &= ~QCOW_OFLAG_COPIED; 442 ret = l2_load(bs, l2_offset, &l2_table); 443 if (ret < 0) { 444 return ret; 445 } 446 447 /* find the cluster offset for the given disk offset */ 448 449 l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1); 450 *cluster_offset = be64_to_cpu(l2_table[l2_index]); 451 nb_clusters = size_to_clusters(s, nb_needed << 9); 452 453 if (!*cluster_offset) { 454 /* how many empty clusters ? */ 455 c = count_contiguous_free_clusters(nb_clusters, &l2_table[l2_index]); 456 } else { 457 /* how many allocated clusters ? */ 458 c = count_contiguous_clusters(nb_clusters, s->cluster_size, 459 &l2_table[l2_index], 0, QCOW_OFLAG_COPIED); 460 } 461 462 qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); 463 464 nb_available = (c * s->cluster_sectors); 465 out: 466 if (nb_available > nb_needed) 467 nb_available = nb_needed; 468 469 *num = nb_available - index_in_cluster; 470 471 *cluster_offset &=~QCOW_OFLAG_COPIED; 472 return 0; 473 } 474 475 /* 476 * get_cluster_table 477 * 478 * for a given disk offset, load (and allocate if needed) 479 * the l2 table. 480 * 481 * the l2 table offset in the qcow2 file and the cluster index 482 * in the l2 table are given to the caller. 483 * 484 * Returns 0 on success, -errno in failure case 485 */ 486 static int get_cluster_table(BlockDriverState *bs, uint64_t offset, 487 uint64_t **new_l2_table, 488 uint64_t *new_l2_offset, 489 int *new_l2_index) 490 { 491 BDRVQcowState *s = bs->opaque; 492 unsigned int l1_index, l2_index; 493 uint64_t l2_offset; 494 uint64_t *l2_table = NULL; 495 int ret; 496 497 /* seek the the l2 offset in the l1 table */ 498 499 l1_index = offset >> (s->l2_bits + s->cluster_bits); 500 if (l1_index >= s->l1_size) { 501 ret = qcow2_grow_l1_table(bs, l1_index + 1, false); 502 if (ret < 0) { 503 return ret; 504 } 505 } 506 l2_offset = s->l1_table[l1_index]; 507 508 /* seek the l2 table of the given l2 offset */ 509 510 if (l2_offset & QCOW_OFLAG_COPIED) { 511 /* load the l2 table in memory */ 512 l2_offset &= ~QCOW_OFLAG_COPIED; 513 ret = l2_load(bs, l2_offset, &l2_table); 514 if (ret < 0) { 515 return ret; 516 } 517 } else { 518 /* First allocate a new L2 table (and do COW if needed) */ 519 ret = l2_allocate(bs, l1_index, &l2_table); 520 if (ret < 0) { 521 return ret; 522 } 523 524 /* Then decrease the refcount of the old table */ 525 if (l2_offset) { 526 qcow2_free_clusters(bs, l2_offset, s->l2_size * sizeof(uint64_t)); 527 } 528 l2_offset = s->l1_table[l1_index] & ~QCOW_OFLAG_COPIED; 529 } 530 531 /* find the cluster offset for the given disk offset */ 532 533 l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1); 534 535 *new_l2_table = l2_table; 536 *new_l2_offset = l2_offset; 537 *new_l2_index = l2_index; 538 539 return 0; 540 } 541 542 /* 543 * alloc_compressed_cluster_offset 544 * 545 * For a given offset of the disk image, return cluster offset in 546 * qcow2 file. 547 * 548 * If the offset is not found, allocate a new compressed cluster. 549 * 550 * Return the cluster offset if successful, 551 * Return 0, otherwise. 552 * 553 */ 554 555 uint64_t qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs, 556 uint64_t offset, 557 int compressed_size) 558 { 559 BDRVQcowState *s = bs->opaque; 560 int l2_index, ret; 561 uint64_t l2_offset, *l2_table; 562 int64_t cluster_offset; 563 int nb_csectors; 564 565 ret = get_cluster_table(bs, offset, &l2_table, &l2_offset, &l2_index); 566 if (ret < 0) { 567 return 0; 568 } 569 570 cluster_offset = be64_to_cpu(l2_table[l2_index]); 571 if (cluster_offset & QCOW_OFLAG_COPIED) 572 return cluster_offset & ~QCOW_OFLAG_COPIED; 573 574 if (cluster_offset) 575 qcow2_free_any_clusters(bs, cluster_offset, 1); 576 577 cluster_offset = qcow2_alloc_bytes(bs, compressed_size); 578 if (cluster_offset < 0) { 579 qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); 580 return 0; 581 } 582 583 nb_csectors = ((cluster_offset + compressed_size - 1) >> 9) - 584 (cluster_offset >> 9); 585 586 cluster_offset |= QCOW_OFLAG_COMPRESSED | 587 ((uint64_t)nb_csectors << s->csize_shift); 588 589 /* update L2 table */ 590 591 /* compressed clusters never have the copied flag */ 592 593 BLKDBG_EVENT(bs->file, BLKDBG_L2_UPDATE_COMPRESSED); 594 qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table); 595 l2_table[l2_index] = cpu_to_be64(cluster_offset); 596 ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); 597 if (ret < 0) { 598 return 0; 599 } 600 601 return cluster_offset; 602 } 603 604 int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m) 605 { 606 BDRVQcowState *s = bs->opaque; 607 int i, j = 0, l2_index, ret; 608 uint64_t *old_cluster, start_sect, l2_offset, *l2_table; 609 uint64_t cluster_offset = m->cluster_offset; 610 bool cow = false; 611 612 if (m->nb_clusters == 0) 613 return 0; 614 615 old_cluster = g_malloc(m->nb_clusters * sizeof(uint64_t)); 616 617 /* copy content of unmodified sectors */ 618 start_sect = (m->offset & ~(s->cluster_size - 1)) >> 9; 619 if (m->n_start) { 620 cow = true; 621 ret = copy_sectors(bs, start_sect, cluster_offset, 0, m->n_start); 622 if (ret < 0) 623 goto err; 624 } 625 626 if (m->nb_available & (s->cluster_sectors - 1)) { 627 uint64_t end = m->nb_available & ~(uint64_t)(s->cluster_sectors - 1); 628 cow = true; 629 ret = copy_sectors(bs, start_sect + end, cluster_offset + (end << 9), 630 m->nb_available - end, s->cluster_sectors); 631 if (ret < 0) 632 goto err; 633 } 634 635 /* 636 * Update L2 table. 637 * 638 * Before we update the L2 table to actually point to the new cluster, we 639 * need to be sure that the refcounts have been increased and COW was 640 * handled. 641 */ 642 if (cow) { 643 qcow2_cache_depends_on_flush(s->l2_table_cache); 644 } 645 646 qcow2_cache_set_dependency(bs, s->l2_table_cache, s->refcount_block_cache); 647 ret = get_cluster_table(bs, m->offset, &l2_table, &l2_offset, &l2_index); 648 if (ret < 0) { 649 goto err; 650 } 651 qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table); 652 653 for (i = 0; i < m->nb_clusters; i++) { 654 /* if two concurrent writes happen to the same unallocated cluster 655 * each write allocates separate cluster and writes data concurrently. 656 * The first one to complete updates l2 table with pointer to its 657 * cluster the second one has to do RMW (which is done above by 658 * copy_sectors()), update l2 table with its cluster pointer and free 659 * old cluster. This is what this loop does */ 660 if(l2_table[l2_index + i] != 0) 661 old_cluster[j++] = l2_table[l2_index + i]; 662 663 l2_table[l2_index + i] = cpu_to_be64((cluster_offset + 664 (i << s->cluster_bits)) | QCOW_OFLAG_COPIED); 665 } 666 667 668 ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); 669 if (ret < 0) { 670 goto err; 671 } 672 673 /* 674 * If this was a COW, we need to decrease the refcount of the old cluster. 675 * Also flush bs->file to get the right order for L2 and refcount update. 676 */ 677 if (j != 0) { 678 for (i = 0; i < j; i++) { 679 qcow2_free_any_clusters(bs, 680 be64_to_cpu(old_cluster[i]) & ~QCOW_OFLAG_COPIED, 1); 681 } 682 } 683 684 ret = 0; 685 err: 686 g_free(old_cluster); 687 return ret; 688 } 689 690 /* 691 * alloc_cluster_offset 692 * 693 * For a given offset of the disk image, return cluster offset in qcow2 file. 694 * If the offset is not found, allocate a new cluster. 695 * 696 * If the cluster was already allocated, m->nb_clusters is set to 0, 697 * m->depends_on is set to NULL and the other fields in m are meaningless. 698 * 699 * If the cluster is newly allocated, m->nb_clusters is set to the number of 700 * contiguous clusters that have been allocated. In this case, the other 701 * fields of m are valid and contain information about the first allocated 702 * cluster. 703 * 704 * If the request conflicts with another write request in flight, the coroutine 705 * is queued and will be reentered when the dependency has completed. 706 * 707 * Return 0 on success and -errno in error cases 708 */ 709 int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset, 710 int n_start, int n_end, int *num, QCowL2Meta *m) 711 { 712 BDRVQcowState *s = bs->opaque; 713 int l2_index, ret; 714 uint64_t l2_offset, *l2_table; 715 int64_t cluster_offset; 716 unsigned int nb_clusters, i = 0; 717 QCowL2Meta *old_alloc; 718 719 ret = get_cluster_table(bs, offset, &l2_table, &l2_offset, &l2_index); 720 if (ret < 0) { 721 return ret; 722 } 723 724 again: 725 nb_clusters = size_to_clusters(s, n_end << 9); 726 727 nb_clusters = MIN(nb_clusters, s->l2_size - l2_index); 728 729 cluster_offset = be64_to_cpu(l2_table[l2_index]); 730 731 /* We keep all QCOW_OFLAG_COPIED clusters */ 732 733 if (cluster_offset & QCOW_OFLAG_COPIED) { 734 nb_clusters = count_contiguous_clusters(nb_clusters, s->cluster_size, 735 &l2_table[l2_index], 0, 0); 736 737 cluster_offset &= ~QCOW_OFLAG_COPIED; 738 m->nb_clusters = 0; 739 m->depends_on = NULL; 740 741 goto out; 742 } 743 744 /* for the moment, multiple compressed clusters are not managed */ 745 746 if (cluster_offset & QCOW_OFLAG_COMPRESSED) 747 nb_clusters = 1; 748 749 /* how many available clusters ? */ 750 751 while (i < nb_clusters) { 752 i += count_contiguous_clusters(nb_clusters - i, s->cluster_size, 753 &l2_table[l2_index], i, 0); 754 if ((i >= nb_clusters) || be64_to_cpu(l2_table[l2_index + i])) { 755 break; 756 } 757 758 i += count_contiguous_free_clusters(nb_clusters - i, 759 &l2_table[l2_index + i]); 760 if (i >= nb_clusters) { 761 break; 762 } 763 764 cluster_offset = be64_to_cpu(l2_table[l2_index + i]); 765 766 if ((cluster_offset & QCOW_OFLAG_COPIED) || 767 (cluster_offset & QCOW_OFLAG_COMPRESSED)) 768 break; 769 } 770 assert(i <= nb_clusters); 771 nb_clusters = i; 772 773 /* 774 * Check if there already is an AIO write request in flight which allocates 775 * the same cluster. In this case we need to wait until the previous 776 * request has completed and updated the L2 table accordingly. 777 */ 778 QLIST_FOREACH(old_alloc, &s->cluster_allocs, next_in_flight) { 779 780 uint64_t end_offset = offset + nb_clusters * s->cluster_size; 781 uint64_t old_offset = old_alloc->offset; 782 uint64_t old_end_offset = old_alloc->offset + 783 old_alloc->nb_clusters * s->cluster_size; 784 785 if (end_offset < old_offset || offset > old_end_offset) { 786 /* No intersection */ 787 } else { 788 if (offset < old_offset) { 789 /* Stop at the start of a running allocation */ 790 nb_clusters = (old_offset - offset) >> s->cluster_bits; 791 } else { 792 nb_clusters = 0; 793 } 794 795 if (nb_clusters == 0) { 796 /* Wait for the dependency to complete. We need to recheck 797 * the free/allocated clusters when we continue. */ 798 qemu_co_mutex_unlock(&s->lock); 799 qemu_co_queue_wait(&old_alloc->dependent_requests); 800 qemu_co_mutex_lock(&s->lock); 801 goto again; 802 } 803 } 804 } 805 806 if (!nb_clusters) { 807 abort(); 808 } 809 810 QLIST_INSERT_HEAD(&s->cluster_allocs, m, next_in_flight); 811 812 /* allocate a new cluster */ 813 814 cluster_offset = qcow2_alloc_clusters(bs, nb_clusters * s->cluster_size); 815 if (cluster_offset < 0) { 816 ret = cluster_offset; 817 goto fail; 818 } 819 820 /* save info needed for meta data update */ 821 m->offset = offset; 822 m->n_start = n_start; 823 m->nb_clusters = nb_clusters; 824 825 out: 826 ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); 827 if (ret < 0) { 828 goto fail_put; 829 } 830 831 m->nb_available = MIN(nb_clusters << (s->cluster_bits - 9), n_end); 832 m->cluster_offset = cluster_offset; 833 834 *num = m->nb_available - n_start; 835 836 return 0; 837 838 fail: 839 qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); 840 fail_put: 841 QLIST_REMOVE(m, next_in_flight); 842 return ret; 843 } 844 845 static int decompress_buffer(uint8_t *out_buf, int out_buf_size, 846 const uint8_t *buf, int buf_size) 847 { 848 z_stream strm1, *strm = &strm1; 849 int ret, out_len; 850 851 memset(strm, 0, sizeof(*strm)); 852 853 strm->next_in = (uint8_t *)buf; 854 strm->avail_in = buf_size; 855 strm->next_out = out_buf; 856 strm->avail_out = out_buf_size; 857 858 ret = inflateInit2(strm, -12); 859 if (ret != Z_OK) 860 return -1; 861 ret = inflate(strm, Z_FINISH); 862 out_len = strm->next_out - out_buf; 863 if ((ret != Z_STREAM_END && ret != Z_BUF_ERROR) || 864 out_len != out_buf_size) { 865 inflateEnd(strm); 866 return -1; 867 } 868 inflateEnd(strm); 869 return 0; 870 } 871 872 int qcow2_decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset) 873 { 874 BDRVQcowState *s = bs->opaque; 875 int ret, csize, nb_csectors, sector_offset; 876 uint64_t coffset; 877 878 coffset = cluster_offset & s->cluster_offset_mask; 879 if (s->cluster_cache_offset != coffset) { 880 nb_csectors = ((cluster_offset >> s->csize_shift) & s->csize_mask) + 1; 881 sector_offset = coffset & 511; 882 csize = nb_csectors * 512 - sector_offset; 883 BLKDBG_EVENT(bs->file, BLKDBG_READ_COMPRESSED); 884 ret = bdrv_read(bs->file, coffset >> 9, s->cluster_data, nb_csectors); 885 if (ret < 0) { 886 return ret; 887 } 888 if (decompress_buffer(s->cluster_cache, s->cluster_size, 889 s->cluster_data + sector_offset, csize) < 0) { 890 return -EIO; 891 } 892 s->cluster_cache_offset = coffset; 893 } 894 return 0; 895 } 896 897 /* 898 * This discards as many clusters of nb_clusters as possible at once (i.e. 899 * all clusters in the same L2 table) and returns the number of discarded 900 * clusters. 901 */ 902 static int discard_single_l2(BlockDriverState *bs, uint64_t offset, 903 unsigned int nb_clusters) 904 { 905 BDRVQcowState *s = bs->opaque; 906 uint64_t l2_offset, *l2_table; 907 int l2_index; 908 int ret; 909 int i; 910 911 ret = get_cluster_table(bs, offset, &l2_table, &l2_offset, &l2_index); 912 if (ret < 0) { 913 return ret; 914 } 915 916 /* Limit nb_clusters to one L2 table */ 917 nb_clusters = MIN(nb_clusters, s->l2_size - l2_index); 918 919 for (i = 0; i < nb_clusters; i++) { 920 uint64_t old_offset; 921 922 old_offset = be64_to_cpu(l2_table[l2_index + i]); 923 old_offset &= ~QCOW_OFLAG_COPIED; 924 925 if (old_offset == 0) { 926 continue; 927 } 928 929 /* First remove L2 entries */ 930 qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table); 931 l2_table[l2_index + i] = cpu_to_be64(0); 932 933 /* Then decrease the refcount */ 934 qcow2_free_any_clusters(bs, old_offset, 1); 935 } 936 937 ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); 938 if (ret < 0) { 939 return ret; 940 } 941 942 return nb_clusters; 943 } 944 945 int qcow2_discard_clusters(BlockDriverState *bs, uint64_t offset, 946 int nb_sectors) 947 { 948 BDRVQcowState *s = bs->opaque; 949 uint64_t end_offset; 950 unsigned int nb_clusters; 951 int ret; 952 953 end_offset = offset + (nb_sectors << BDRV_SECTOR_BITS); 954 955 /* Round start up and end down */ 956 offset = align_offset(offset, s->cluster_size); 957 end_offset &= ~(s->cluster_size - 1); 958 959 if (offset > end_offset) { 960 return 0; 961 } 962 963 nb_clusters = size_to_clusters(s, end_offset - offset); 964 965 /* Each L2 table is handled by its own loop iteration */ 966 while (nb_clusters > 0) { 967 ret = discard_single_l2(bs, offset, nb_clusters); 968 if (ret < 0) { 969 return ret; 970 } 971 972 nb_clusters -= ret; 973 offset += (ret * s->cluster_size); 974 } 975 976 return 0; 977 } 978