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 fprintf(stderr, "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 static int coroutine_fn copy_sectors(BlockDriverState *bs, 293 uint64_t start_sect, 294 uint64_t cluster_offset, 295 int n_start, int n_end) 296 { 297 BDRVQcowState *s = bs->opaque; 298 QEMUIOVector qiov; 299 struct iovec iov; 300 int n, ret; 301 302 /* 303 * If this is the last cluster and it is only partially used, we must only 304 * copy until the end of the image, or bdrv_check_request will fail for the 305 * bdrv_read/write calls below. 306 */ 307 if (start_sect + n_end > bs->total_sectors) { 308 n_end = bs->total_sectors - start_sect; 309 } 310 311 n = n_end - n_start; 312 if (n <= 0) { 313 return 0; 314 } 315 316 iov.iov_len = n * BDRV_SECTOR_SIZE; 317 iov.iov_base = qemu_blockalign(bs, iov.iov_len); 318 319 qemu_iovec_init_external(&qiov, &iov, 1); 320 321 BLKDBG_EVENT(bs->file, BLKDBG_COW_READ); 322 323 /* Call .bdrv_co_readv() directly instead of using the public block-layer 324 * interface. This avoids double I/O throttling and request tracking, 325 * which can lead to deadlock when block layer copy-on-read is enabled. 326 */ 327 ret = bs->drv->bdrv_co_readv(bs, start_sect + n_start, n, &qiov); 328 if (ret < 0) { 329 goto out; 330 } 331 332 if (s->crypt_method) { 333 qcow2_encrypt_sectors(s, start_sect + n_start, 334 iov.iov_base, iov.iov_base, n, 1, 335 &s->aes_encrypt_key); 336 } 337 338 BLKDBG_EVENT(bs->file, BLKDBG_COW_WRITE); 339 ret = bdrv_co_writev(bs->file, (cluster_offset >> 9) + n_start, n, &qiov); 340 if (ret < 0) { 341 goto out; 342 } 343 344 ret = 0; 345 out: 346 qemu_vfree(iov.iov_base); 347 return ret; 348 } 349 350 351 /* 352 * get_cluster_offset 353 * 354 * For a given offset of the disk image, find the cluster offset in 355 * qcow2 file. The offset is stored in *cluster_offset. 356 * 357 * on entry, *num is the number of contiguous sectors we'd like to 358 * access following offset. 359 * 360 * on exit, *num is the number of contiguous sectors we can read. 361 * 362 * Return 0, if the offset is found 363 * Return -errno, otherwise. 364 * 365 */ 366 367 int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset, 368 int *num, uint64_t *cluster_offset) 369 { 370 BDRVQcowState *s = bs->opaque; 371 unsigned int l1_index, l2_index; 372 uint64_t l2_offset, *l2_table; 373 int l1_bits, c; 374 unsigned int index_in_cluster, nb_clusters; 375 uint64_t nb_available, nb_needed; 376 int ret; 377 378 index_in_cluster = (offset >> 9) & (s->cluster_sectors - 1); 379 nb_needed = *num + index_in_cluster; 380 381 l1_bits = s->l2_bits + s->cluster_bits; 382 383 /* compute how many bytes there are between the offset and 384 * the end of the l1 entry 385 */ 386 387 nb_available = (1ULL << l1_bits) - (offset & ((1ULL << l1_bits) - 1)); 388 389 /* compute the number of available sectors */ 390 391 nb_available = (nb_available >> 9) + index_in_cluster; 392 393 if (nb_needed > nb_available) { 394 nb_needed = nb_available; 395 } 396 397 *cluster_offset = 0; 398 399 /* seek the the l2 offset in the l1 table */ 400 401 l1_index = offset >> l1_bits; 402 if (l1_index >= s->l1_size) 403 goto out; 404 405 l2_offset = s->l1_table[l1_index]; 406 407 /* seek the l2 table of the given l2 offset */ 408 409 if (!l2_offset) 410 goto out; 411 412 /* load the l2 table in memory */ 413 414 l2_offset &= ~QCOW_OFLAG_COPIED; 415 ret = l2_load(bs, l2_offset, &l2_table); 416 if (ret < 0) { 417 return ret; 418 } 419 420 /* find the cluster offset for the given disk offset */ 421 422 l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1); 423 *cluster_offset = be64_to_cpu(l2_table[l2_index]); 424 nb_clusters = size_to_clusters(s, nb_needed << 9); 425 426 if (!*cluster_offset) { 427 /* how many empty clusters ? */ 428 c = count_contiguous_free_clusters(nb_clusters, &l2_table[l2_index]); 429 } else { 430 /* how many allocated clusters ? */ 431 c = count_contiguous_clusters(nb_clusters, s->cluster_size, 432 &l2_table[l2_index], 0, QCOW_OFLAG_COPIED); 433 } 434 435 qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); 436 437 nb_available = (c * s->cluster_sectors); 438 out: 439 if (nb_available > nb_needed) 440 nb_available = nb_needed; 441 442 *num = nb_available - index_in_cluster; 443 444 *cluster_offset &=~QCOW_OFLAG_COPIED; 445 return 0; 446 } 447 448 /* 449 * get_cluster_table 450 * 451 * for a given disk offset, load (and allocate if needed) 452 * the l2 table. 453 * 454 * the l2 table offset in the qcow2 file and the cluster index 455 * in the l2 table are given to the caller. 456 * 457 * Returns 0 on success, -errno in failure case 458 */ 459 static int get_cluster_table(BlockDriverState *bs, uint64_t offset, 460 uint64_t **new_l2_table, 461 uint64_t *new_l2_offset, 462 int *new_l2_index) 463 { 464 BDRVQcowState *s = bs->opaque; 465 unsigned int l1_index, l2_index; 466 uint64_t l2_offset; 467 uint64_t *l2_table = NULL; 468 int ret; 469 470 /* seek the the l2 offset in the l1 table */ 471 472 l1_index = offset >> (s->l2_bits + s->cluster_bits); 473 if (l1_index >= s->l1_size) { 474 ret = qcow2_grow_l1_table(bs, l1_index + 1, false); 475 if (ret < 0) { 476 return ret; 477 } 478 } 479 l2_offset = s->l1_table[l1_index]; 480 481 /* seek the l2 table of the given l2 offset */ 482 483 if (l2_offset & QCOW_OFLAG_COPIED) { 484 /* load the l2 table in memory */ 485 l2_offset &= ~QCOW_OFLAG_COPIED; 486 ret = l2_load(bs, l2_offset, &l2_table); 487 if (ret < 0) { 488 return ret; 489 } 490 } else { 491 /* First allocate a new L2 table (and do COW if needed) */ 492 ret = l2_allocate(bs, l1_index, &l2_table); 493 if (ret < 0) { 494 return ret; 495 } 496 497 /* Then decrease the refcount of the old table */ 498 if (l2_offset) { 499 qcow2_free_clusters(bs, l2_offset, s->l2_size * sizeof(uint64_t)); 500 } 501 l2_offset = s->l1_table[l1_index] & ~QCOW_OFLAG_COPIED; 502 } 503 504 /* find the cluster offset for the given disk offset */ 505 506 l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1); 507 508 *new_l2_table = l2_table; 509 *new_l2_offset = l2_offset; 510 *new_l2_index = l2_index; 511 512 return 0; 513 } 514 515 /* 516 * alloc_compressed_cluster_offset 517 * 518 * For a given offset of the disk image, return cluster offset in 519 * qcow2 file. 520 * 521 * If the offset is not found, allocate a new compressed cluster. 522 * 523 * Return the cluster offset if successful, 524 * Return 0, otherwise. 525 * 526 */ 527 528 uint64_t qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs, 529 uint64_t offset, 530 int compressed_size) 531 { 532 BDRVQcowState *s = bs->opaque; 533 int l2_index, ret; 534 uint64_t l2_offset, *l2_table; 535 int64_t cluster_offset; 536 int nb_csectors; 537 538 ret = get_cluster_table(bs, offset, &l2_table, &l2_offset, &l2_index); 539 if (ret < 0) { 540 return 0; 541 } 542 543 cluster_offset = be64_to_cpu(l2_table[l2_index]); 544 if (cluster_offset & QCOW_OFLAG_COPIED) { 545 qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); 546 return 0; 547 } 548 549 if (cluster_offset) 550 qcow2_free_any_clusters(bs, cluster_offset, 1); 551 552 cluster_offset = qcow2_alloc_bytes(bs, compressed_size); 553 if (cluster_offset < 0) { 554 qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); 555 return 0; 556 } 557 558 nb_csectors = ((cluster_offset + compressed_size - 1) >> 9) - 559 (cluster_offset >> 9); 560 561 cluster_offset |= QCOW_OFLAG_COMPRESSED | 562 ((uint64_t)nb_csectors << s->csize_shift); 563 564 /* update L2 table */ 565 566 /* compressed clusters never have the copied flag */ 567 568 BLKDBG_EVENT(bs->file, BLKDBG_L2_UPDATE_COMPRESSED); 569 qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table); 570 l2_table[l2_index] = cpu_to_be64(cluster_offset); 571 ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); 572 if (ret < 0) { 573 return 0; 574 } 575 576 return cluster_offset; 577 } 578 579 int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m) 580 { 581 BDRVQcowState *s = bs->opaque; 582 int i, j = 0, l2_index, ret; 583 uint64_t *old_cluster, start_sect, l2_offset, *l2_table; 584 uint64_t cluster_offset = m->cluster_offset; 585 bool cow = false; 586 587 if (m->nb_clusters == 0) 588 return 0; 589 590 old_cluster = g_malloc(m->nb_clusters * sizeof(uint64_t)); 591 592 /* copy content of unmodified sectors */ 593 start_sect = (m->offset & ~(s->cluster_size - 1)) >> 9; 594 if (m->n_start) { 595 cow = true; 596 qemu_co_mutex_unlock(&s->lock); 597 ret = copy_sectors(bs, start_sect, cluster_offset, 0, m->n_start); 598 qemu_co_mutex_lock(&s->lock); 599 if (ret < 0) 600 goto err; 601 } 602 603 if (m->nb_available & (s->cluster_sectors - 1)) { 604 uint64_t end = m->nb_available & ~(uint64_t)(s->cluster_sectors - 1); 605 cow = true; 606 qemu_co_mutex_unlock(&s->lock); 607 ret = copy_sectors(bs, start_sect + end, cluster_offset + (end << 9), 608 m->nb_available - end, s->cluster_sectors); 609 qemu_co_mutex_lock(&s->lock); 610 if (ret < 0) 611 goto err; 612 } 613 614 /* 615 * Update L2 table. 616 * 617 * Before we update the L2 table to actually point to the new cluster, we 618 * need to be sure that the refcounts have been increased and COW was 619 * handled. 620 */ 621 if (cow) { 622 qcow2_cache_depends_on_flush(s->l2_table_cache); 623 } 624 625 qcow2_cache_set_dependency(bs, s->l2_table_cache, s->refcount_block_cache); 626 ret = get_cluster_table(bs, m->offset, &l2_table, &l2_offset, &l2_index); 627 if (ret < 0) { 628 goto err; 629 } 630 qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table); 631 632 for (i = 0; i < m->nb_clusters; i++) { 633 /* if two concurrent writes happen to the same unallocated cluster 634 * each write allocates separate cluster and writes data concurrently. 635 * The first one to complete updates l2 table with pointer to its 636 * cluster the second one has to do RMW (which is done above by 637 * copy_sectors()), update l2 table with its cluster pointer and free 638 * old cluster. This is what this loop does */ 639 if(l2_table[l2_index + i] != 0) 640 old_cluster[j++] = l2_table[l2_index + i]; 641 642 l2_table[l2_index + i] = cpu_to_be64((cluster_offset + 643 (i << s->cluster_bits)) | QCOW_OFLAG_COPIED); 644 } 645 646 647 ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); 648 if (ret < 0) { 649 goto err; 650 } 651 652 /* 653 * If this was a COW, we need to decrease the refcount of the old cluster. 654 * Also flush bs->file to get the right order for L2 and refcount update. 655 */ 656 if (j != 0) { 657 for (i = 0; i < j; i++) { 658 qcow2_free_any_clusters(bs, 659 be64_to_cpu(old_cluster[i]) & ~QCOW_OFLAG_COPIED, 1); 660 } 661 } 662 663 ret = 0; 664 err: 665 g_free(old_cluster); 666 return ret; 667 } 668 669 /* 670 * alloc_cluster_offset 671 * 672 * For a given offset of the disk image, return cluster offset in qcow2 file. 673 * If the offset is not found, allocate a new cluster. 674 * 675 * If the cluster was already allocated, m->nb_clusters is set to 0, 676 * other fields in m are meaningless. 677 * 678 * If the cluster is newly allocated, m->nb_clusters is set to the number of 679 * contiguous clusters that have been allocated. In this case, the other 680 * fields of m are valid and contain information about the first allocated 681 * cluster. 682 * 683 * If the request conflicts with another write request in flight, the coroutine 684 * is queued and will be reentered when the dependency has completed. 685 * 686 * Return 0 on success and -errno in error cases 687 */ 688 int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset, 689 int n_start, int n_end, int *num, QCowL2Meta *m) 690 { 691 BDRVQcowState *s = bs->opaque; 692 int l2_index, ret; 693 uint64_t l2_offset, *l2_table; 694 int64_t cluster_offset; 695 unsigned int nb_clusters, i = 0; 696 QCowL2Meta *old_alloc; 697 698 ret = get_cluster_table(bs, offset, &l2_table, &l2_offset, &l2_index); 699 if (ret < 0) { 700 return ret; 701 } 702 703 again: 704 nb_clusters = size_to_clusters(s, n_end << 9); 705 706 nb_clusters = MIN(nb_clusters, s->l2_size - l2_index); 707 708 cluster_offset = be64_to_cpu(l2_table[l2_index]); 709 710 /* We keep all QCOW_OFLAG_COPIED clusters */ 711 712 if (cluster_offset & QCOW_OFLAG_COPIED) { 713 nb_clusters = count_contiguous_clusters(nb_clusters, s->cluster_size, 714 &l2_table[l2_index], 0, 0); 715 716 cluster_offset &= ~QCOW_OFLAG_COPIED; 717 m->nb_clusters = 0; 718 719 goto out; 720 } 721 722 /* for the moment, multiple compressed clusters are not managed */ 723 724 if (cluster_offset & QCOW_OFLAG_COMPRESSED) 725 nb_clusters = 1; 726 727 /* how many available clusters ? */ 728 729 while (i < nb_clusters) { 730 i += count_contiguous_clusters(nb_clusters - i, s->cluster_size, 731 &l2_table[l2_index], i, 0); 732 if ((i >= nb_clusters) || be64_to_cpu(l2_table[l2_index + i])) { 733 break; 734 } 735 736 i += count_contiguous_free_clusters(nb_clusters - i, 737 &l2_table[l2_index + i]); 738 if (i >= nb_clusters) { 739 break; 740 } 741 742 cluster_offset = be64_to_cpu(l2_table[l2_index + i]); 743 744 if ((cluster_offset & QCOW_OFLAG_COPIED) || 745 (cluster_offset & QCOW_OFLAG_COMPRESSED)) 746 break; 747 } 748 assert(i <= nb_clusters); 749 nb_clusters = i; 750 751 /* 752 * Check if there already is an AIO write request in flight which allocates 753 * the same cluster. In this case we need to wait until the previous 754 * request has completed and updated the L2 table accordingly. 755 */ 756 QLIST_FOREACH(old_alloc, &s->cluster_allocs, next_in_flight) { 757 758 uint64_t start = offset >> s->cluster_bits; 759 uint64_t end = start + nb_clusters; 760 uint64_t old_start = old_alloc->offset >> s->cluster_bits; 761 uint64_t old_end = old_start + old_alloc->nb_clusters; 762 763 if (end < old_start || start > old_end) { 764 /* No intersection */ 765 } else { 766 if (start < old_start) { 767 /* Stop at the start of a running allocation */ 768 nb_clusters = old_start - start; 769 } else { 770 nb_clusters = 0; 771 } 772 773 if (nb_clusters == 0) { 774 /* Wait for the dependency to complete. We need to recheck 775 * the free/allocated clusters when we continue. */ 776 qemu_co_mutex_unlock(&s->lock); 777 qemu_co_queue_wait(&old_alloc->dependent_requests); 778 qemu_co_mutex_lock(&s->lock); 779 goto again; 780 } 781 } 782 } 783 784 if (!nb_clusters) { 785 abort(); 786 } 787 788 /* save info needed for meta data update */ 789 m->offset = offset; 790 m->n_start = n_start; 791 m->nb_clusters = nb_clusters; 792 793 QLIST_INSERT_HEAD(&s->cluster_allocs, m, next_in_flight); 794 795 /* allocate a new cluster */ 796 797 cluster_offset = qcow2_alloc_clusters(bs, nb_clusters * s->cluster_size); 798 if (cluster_offset < 0) { 799 ret = cluster_offset; 800 goto fail; 801 } 802 803 out: 804 ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); 805 if (ret < 0) { 806 goto fail_put; 807 } 808 809 m->nb_available = MIN(nb_clusters << (s->cluster_bits - 9), n_end); 810 m->cluster_offset = cluster_offset; 811 812 *num = m->nb_available - n_start; 813 814 return 0; 815 816 fail: 817 qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); 818 fail_put: 819 QLIST_REMOVE(m, next_in_flight); 820 return ret; 821 } 822 823 static int decompress_buffer(uint8_t *out_buf, int out_buf_size, 824 const uint8_t *buf, int buf_size) 825 { 826 z_stream strm1, *strm = &strm1; 827 int ret, out_len; 828 829 memset(strm, 0, sizeof(*strm)); 830 831 strm->next_in = (uint8_t *)buf; 832 strm->avail_in = buf_size; 833 strm->next_out = out_buf; 834 strm->avail_out = out_buf_size; 835 836 ret = inflateInit2(strm, -12); 837 if (ret != Z_OK) 838 return -1; 839 ret = inflate(strm, Z_FINISH); 840 out_len = strm->next_out - out_buf; 841 if ((ret != Z_STREAM_END && ret != Z_BUF_ERROR) || 842 out_len != out_buf_size) { 843 inflateEnd(strm); 844 return -1; 845 } 846 inflateEnd(strm); 847 return 0; 848 } 849 850 int qcow2_decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset) 851 { 852 BDRVQcowState *s = bs->opaque; 853 int ret, csize, nb_csectors, sector_offset; 854 uint64_t coffset; 855 856 coffset = cluster_offset & s->cluster_offset_mask; 857 if (s->cluster_cache_offset != coffset) { 858 nb_csectors = ((cluster_offset >> s->csize_shift) & s->csize_mask) + 1; 859 sector_offset = coffset & 511; 860 csize = nb_csectors * 512 - sector_offset; 861 BLKDBG_EVENT(bs->file, BLKDBG_READ_COMPRESSED); 862 ret = bdrv_read(bs->file, coffset >> 9, s->cluster_data, nb_csectors); 863 if (ret < 0) { 864 return ret; 865 } 866 if (decompress_buffer(s->cluster_cache, s->cluster_size, 867 s->cluster_data + sector_offset, csize) < 0) { 868 return -EIO; 869 } 870 s->cluster_cache_offset = coffset; 871 } 872 return 0; 873 } 874 875 /* 876 * This discards as many clusters of nb_clusters as possible at once (i.e. 877 * all clusters in the same L2 table) and returns the number of discarded 878 * clusters. 879 */ 880 static int discard_single_l2(BlockDriverState *bs, uint64_t offset, 881 unsigned int nb_clusters) 882 { 883 BDRVQcowState *s = bs->opaque; 884 uint64_t l2_offset, *l2_table; 885 int l2_index; 886 int ret; 887 int i; 888 889 ret = get_cluster_table(bs, offset, &l2_table, &l2_offset, &l2_index); 890 if (ret < 0) { 891 return ret; 892 } 893 894 /* Limit nb_clusters to one L2 table */ 895 nb_clusters = MIN(nb_clusters, s->l2_size - l2_index); 896 897 for (i = 0; i < nb_clusters; i++) { 898 uint64_t old_offset; 899 900 old_offset = be64_to_cpu(l2_table[l2_index + i]); 901 old_offset &= ~QCOW_OFLAG_COPIED; 902 903 if (old_offset == 0) { 904 continue; 905 } 906 907 /* First remove L2 entries */ 908 qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table); 909 l2_table[l2_index + i] = cpu_to_be64(0); 910 911 /* Then decrease the refcount */ 912 qcow2_free_any_clusters(bs, old_offset, 1); 913 } 914 915 ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); 916 if (ret < 0) { 917 return ret; 918 } 919 920 return nb_clusters; 921 } 922 923 int qcow2_discard_clusters(BlockDriverState *bs, uint64_t offset, 924 int nb_sectors) 925 { 926 BDRVQcowState *s = bs->opaque; 927 uint64_t end_offset; 928 unsigned int nb_clusters; 929 int ret; 930 931 end_offset = offset + (nb_sectors << BDRV_SECTOR_BITS); 932 933 /* Round start up and end down */ 934 offset = align_offset(offset, s->cluster_size); 935 end_offset &= ~(s->cluster_size - 1); 936 937 if (offset > end_offset) { 938 return 0; 939 } 940 941 nb_clusters = size_to_clusters(s, end_offset - offset); 942 943 /* Each L2 table is handled by its own loop iteration */ 944 while (nb_clusters > 0) { 945 ret = discard_single_l2(bs, offset, nb_clusters); 946 if (ret < 0) { 947 return ret; 948 } 949 950 nb_clusters -= ret; 951 offset += (ret * s->cluster_size); 952 } 953 954 return 0; 955 } 956