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 "qemu-common.h" 26 #include "block_int.h" 27 #include "block/qcow2.h" 28 29 static int64_t alloc_clusters_noref(BlockDriverState *bs, int64_t size); 30 static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs, 31 int64_t offset, int64_t length, 32 int addend); 33 34 35 static int cache_refcount_updates = 0; 36 37 static int write_refcount_block(BlockDriverState *bs) 38 { 39 BDRVQcowState *s = bs->opaque; 40 size_t size = s->cluster_size; 41 42 if (s->refcount_block_cache_offset == 0) { 43 return 0; 44 } 45 46 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_UPDATE); 47 if (bdrv_pwrite_sync(bs->file, s->refcount_block_cache_offset, 48 s->refcount_block_cache, size) < 0) 49 { 50 return -EIO; 51 } 52 53 return 0; 54 } 55 56 /*********************************************************/ 57 /* refcount handling */ 58 59 int qcow2_refcount_init(BlockDriverState *bs) 60 { 61 BDRVQcowState *s = bs->opaque; 62 int ret, refcount_table_size2, i; 63 64 s->refcount_block_cache = qemu_malloc(s->cluster_size); 65 refcount_table_size2 = s->refcount_table_size * sizeof(uint64_t); 66 s->refcount_table = qemu_malloc(refcount_table_size2); 67 if (s->refcount_table_size > 0) { 68 BLKDBG_EVENT(bs->file, BLKDBG_REFTABLE_LOAD); 69 ret = bdrv_pread(bs->file, s->refcount_table_offset, 70 s->refcount_table, refcount_table_size2); 71 if (ret != refcount_table_size2) 72 goto fail; 73 for(i = 0; i < s->refcount_table_size; i++) 74 be64_to_cpus(&s->refcount_table[i]); 75 } 76 return 0; 77 fail: 78 return -ENOMEM; 79 } 80 81 void qcow2_refcount_close(BlockDriverState *bs) 82 { 83 BDRVQcowState *s = bs->opaque; 84 qemu_free(s->refcount_block_cache); 85 qemu_free(s->refcount_table); 86 } 87 88 89 static int load_refcount_block(BlockDriverState *bs, 90 int64_t refcount_block_offset) 91 { 92 BDRVQcowState *s = bs->opaque; 93 int ret; 94 95 if (cache_refcount_updates) { 96 ret = write_refcount_block(bs); 97 if (ret < 0) { 98 return ret; 99 } 100 } 101 102 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_LOAD); 103 ret = bdrv_pread(bs->file, refcount_block_offset, s->refcount_block_cache, 104 s->cluster_size); 105 if (ret < 0) { 106 return ret; 107 } 108 109 s->refcount_block_cache_offset = refcount_block_offset; 110 return 0; 111 } 112 113 /* 114 * Returns the refcount of the cluster given by its index. Any non-negative 115 * return value is the refcount of the cluster, negative values are -errno 116 * and indicate an error. 117 */ 118 static int get_refcount(BlockDriverState *bs, int64_t cluster_index) 119 { 120 BDRVQcowState *s = bs->opaque; 121 int refcount_table_index, block_index; 122 int64_t refcount_block_offset; 123 int ret; 124 125 refcount_table_index = cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT); 126 if (refcount_table_index >= s->refcount_table_size) 127 return 0; 128 refcount_block_offset = s->refcount_table[refcount_table_index]; 129 if (!refcount_block_offset) 130 return 0; 131 if (refcount_block_offset != s->refcount_block_cache_offset) { 132 /* better than nothing: return allocated if read error */ 133 ret = load_refcount_block(bs, refcount_block_offset); 134 if (ret < 0) { 135 return ret; 136 } 137 } 138 block_index = cluster_index & 139 ((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1); 140 return be16_to_cpu(s->refcount_block_cache[block_index]); 141 } 142 143 /* 144 * Rounds the refcount table size up to avoid growing the table for each single 145 * refcount block that is allocated. 146 */ 147 static unsigned int next_refcount_table_size(BDRVQcowState *s, 148 unsigned int min_size) 149 { 150 unsigned int min_clusters = (min_size >> (s->cluster_bits - 3)) + 1; 151 unsigned int refcount_table_clusters = 152 MAX(1, s->refcount_table_size >> (s->cluster_bits - 3)); 153 154 while (min_clusters > refcount_table_clusters) { 155 refcount_table_clusters = (refcount_table_clusters * 3 + 1) / 2; 156 } 157 158 return refcount_table_clusters << (s->cluster_bits - 3); 159 } 160 161 162 /* Checks if two offsets are described by the same refcount block */ 163 static int in_same_refcount_block(BDRVQcowState *s, uint64_t offset_a, 164 uint64_t offset_b) 165 { 166 uint64_t block_a = offset_a >> (2 * s->cluster_bits - REFCOUNT_SHIFT); 167 uint64_t block_b = offset_b >> (2 * s->cluster_bits - REFCOUNT_SHIFT); 168 169 return (block_a == block_b); 170 } 171 172 /* 173 * Loads a refcount block. If it doesn't exist yet, it is allocated first 174 * (including growing the refcount table if needed). 175 * 176 * Returns the offset of the refcount block on success or -errno in error case 177 */ 178 static int64_t alloc_refcount_block(BlockDriverState *bs, int64_t cluster_index) 179 { 180 BDRVQcowState *s = bs->opaque; 181 unsigned int refcount_table_index; 182 int ret; 183 184 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC); 185 186 /* Find the refcount block for the given cluster */ 187 refcount_table_index = cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT); 188 189 if (refcount_table_index < s->refcount_table_size) { 190 191 uint64_t refcount_block_offset = 192 s->refcount_table[refcount_table_index]; 193 194 /* If it's already there, we're done */ 195 if (refcount_block_offset) { 196 if (refcount_block_offset != s->refcount_block_cache_offset) { 197 ret = load_refcount_block(bs, refcount_block_offset); 198 if (ret < 0) { 199 return ret; 200 } 201 } 202 return refcount_block_offset; 203 } 204 } 205 206 /* 207 * If we came here, we need to allocate something. Something is at least 208 * a cluster for the new refcount block. It may also include a new refcount 209 * table if the old refcount table is too small. 210 * 211 * Note that allocating clusters here needs some special care: 212 * 213 * - We can't use the normal qcow2_alloc_clusters(), it would try to 214 * increase the refcount and very likely we would end up with an endless 215 * recursion. Instead we must place the refcount blocks in a way that 216 * they can describe them themselves. 217 * 218 * - We need to consider that at this point we are inside update_refcounts 219 * and doing the initial refcount increase. This means that some clusters 220 * have already been allocated by the caller, but their refcount isn't 221 * accurate yet. free_cluster_index tells us where this allocation ends 222 * as long as we don't overwrite it by freeing clusters. 223 * 224 * - alloc_clusters_noref and qcow2_free_clusters may load a different 225 * refcount block into the cache 226 */ 227 228 if (cache_refcount_updates) { 229 ret = write_refcount_block(bs); 230 if (ret < 0) { 231 return ret; 232 } 233 } 234 235 /* Allocate the refcount block itself and mark it as used */ 236 int64_t new_block = alloc_clusters_noref(bs, s->cluster_size); 237 if (new_block < 0) { 238 return new_block; 239 } 240 241 #ifdef DEBUG_ALLOC2 242 fprintf(stderr, "qcow2: Allocate refcount block %d for %" PRIx64 243 " at %" PRIx64 "\n", 244 refcount_table_index, cluster_index << s->cluster_bits, new_block); 245 #endif 246 247 if (in_same_refcount_block(s, new_block, cluster_index << s->cluster_bits)) { 248 /* Zero the new refcount block before updating it */ 249 memset(s->refcount_block_cache, 0, s->cluster_size); 250 s->refcount_block_cache_offset = new_block; 251 252 /* The block describes itself, need to update the cache */ 253 int block_index = (new_block >> s->cluster_bits) & 254 ((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1); 255 s->refcount_block_cache[block_index] = cpu_to_be16(1); 256 } else { 257 /* Described somewhere else. This can recurse at most twice before we 258 * arrive at a block that describes itself. */ 259 ret = update_refcount(bs, new_block, s->cluster_size, 1); 260 if (ret < 0) { 261 goto fail_block; 262 } 263 264 /* Initialize the new refcount block only after updating its refcount, 265 * update_refcount uses the refcount cache itself */ 266 memset(s->refcount_block_cache, 0, s->cluster_size); 267 s->refcount_block_cache_offset = new_block; 268 } 269 270 /* Now the new refcount block needs to be written to disk */ 271 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_WRITE); 272 ret = bdrv_pwrite_sync(bs->file, new_block, s->refcount_block_cache, 273 s->cluster_size); 274 if (ret < 0) { 275 goto fail_block; 276 } 277 278 /* If the refcount table is big enough, just hook the block up there */ 279 if (refcount_table_index < s->refcount_table_size) { 280 uint64_t data64 = cpu_to_be64(new_block); 281 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_HOOKUP); 282 ret = bdrv_pwrite_sync(bs->file, 283 s->refcount_table_offset + refcount_table_index * sizeof(uint64_t), 284 &data64, sizeof(data64)); 285 if (ret < 0) { 286 goto fail_block; 287 } 288 289 s->refcount_table[refcount_table_index] = new_block; 290 return new_block; 291 } 292 293 /* 294 * If we come here, we need to grow the refcount table. Again, a new 295 * refcount table needs some space and we can't simply allocate to avoid 296 * endless recursion. 297 * 298 * Therefore let's grab new refcount blocks at the end of the image, which 299 * will describe themselves and the new refcount table. This way we can 300 * reference them only in the new table and do the switch to the new 301 * refcount table at once without producing an inconsistent state in 302 * between. 303 */ 304 BLKDBG_EVENT(bs->file, BLKDBG_REFTABLE_GROW); 305 306 /* Calculate the number of refcount blocks needed so far */ 307 uint64_t refcount_block_clusters = 1 << (s->cluster_bits - REFCOUNT_SHIFT); 308 uint64_t blocks_used = (s->free_cluster_index + 309 refcount_block_clusters - 1) / refcount_block_clusters; 310 311 /* And now we need at least one block more for the new metadata */ 312 uint64_t table_size = next_refcount_table_size(s, blocks_used + 1); 313 uint64_t last_table_size; 314 uint64_t blocks_clusters; 315 do { 316 uint64_t table_clusters = size_to_clusters(s, table_size); 317 blocks_clusters = 1 + 318 ((table_clusters + refcount_block_clusters - 1) 319 / refcount_block_clusters); 320 uint64_t meta_clusters = table_clusters + blocks_clusters; 321 322 last_table_size = table_size; 323 table_size = next_refcount_table_size(s, blocks_used + 324 ((meta_clusters + refcount_block_clusters - 1) 325 / refcount_block_clusters)); 326 327 } while (last_table_size != table_size); 328 329 #ifdef DEBUG_ALLOC2 330 fprintf(stderr, "qcow2: Grow refcount table %" PRId32 " => %" PRId64 "\n", 331 s->refcount_table_size, table_size); 332 #endif 333 334 /* Create the new refcount table and blocks */ 335 uint64_t meta_offset = (blocks_used * refcount_block_clusters) * 336 s->cluster_size; 337 uint64_t table_offset = meta_offset + blocks_clusters * s->cluster_size; 338 uint16_t *new_blocks = qemu_mallocz(blocks_clusters * s->cluster_size); 339 uint64_t *new_table = qemu_mallocz(table_size * sizeof(uint64_t)); 340 341 assert(meta_offset >= (s->free_cluster_index * s->cluster_size)); 342 343 /* Fill the new refcount table */ 344 memcpy(new_table, s->refcount_table, 345 s->refcount_table_size * sizeof(uint64_t)); 346 new_table[refcount_table_index] = new_block; 347 348 int i; 349 for (i = 0; i < blocks_clusters; i++) { 350 new_table[blocks_used + i] = meta_offset + (i * s->cluster_size); 351 } 352 353 /* Fill the refcount blocks */ 354 uint64_t table_clusters = size_to_clusters(s, table_size * sizeof(uint64_t)); 355 int block = 0; 356 for (i = 0; i < table_clusters + blocks_clusters; i++) { 357 new_blocks[block++] = cpu_to_be16(1); 358 } 359 360 /* Write refcount blocks to disk */ 361 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_WRITE_BLOCKS); 362 ret = bdrv_pwrite_sync(bs->file, meta_offset, new_blocks, 363 blocks_clusters * s->cluster_size); 364 qemu_free(new_blocks); 365 if (ret < 0) { 366 goto fail_table; 367 } 368 369 /* Write refcount table to disk */ 370 for(i = 0; i < table_size; i++) { 371 cpu_to_be64s(&new_table[i]); 372 } 373 374 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_WRITE_TABLE); 375 ret = bdrv_pwrite_sync(bs->file, table_offset, new_table, 376 table_size * sizeof(uint64_t)); 377 if (ret < 0) { 378 goto fail_table; 379 } 380 381 for(i = 0; i < table_size; i++) { 382 cpu_to_be64s(&new_table[i]); 383 } 384 385 /* Hook up the new refcount table in the qcow2 header */ 386 uint8_t data[12]; 387 cpu_to_be64w((uint64_t*)data, table_offset); 388 cpu_to_be32w((uint32_t*)(data + 8), table_clusters); 389 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_SWITCH_TABLE); 390 ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, refcount_table_offset), 391 data, sizeof(data)); 392 if (ret < 0) { 393 goto fail_table; 394 } 395 396 /* And switch it in memory */ 397 uint64_t old_table_offset = s->refcount_table_offset; 398 uint64_t old_table_size = s->refcount_table_size; 399 400 qemu_free(s->refcount_table); 401 s->refcount_table = new_table; 402 s->refcount_table_size = table_size; 403 s->refcount_table_offset = table_offset; 404 405 /* Free old table. Remember, we must not change free_cluster_index */ 406 uint64_t old_free_cluster_index = s->free_cluster_index; 407 qcow2_free_clusters(bs, old_table_offset, old_table_size * sizeof(uint64_t)); 408 s->free_cluster_index = old_free_cluster_index; 409 410 ret = load_refcount_block(bs, new_block); 411 if (ret < 0) { 412 goto fail_block; 413 } 414 415 return new_block; 416 417 fail_table: 418 qemu_free(new_table); 419 fail_block: 420 s->refcount_block_cache_offset = 0; 421 return ret; 422 } 423 424 #define REFCOUNTS_PER_SECTOR (512 >> REFCOUNT_SHIFT) 425 static int write_refcount_block_entries(BlockDriverState *bs, 426 int64_t refcount_block_offset, int first_index, int last_index) 427 { 428 BDRVQcowState *s = bs->opaque; 429 size_t size; 430 int ret; 431 432 if (cache_refcount_updates) { 433 return 0; 434 } 435 436 if (first_index < 0) { 437 return 0; 438 } 439 440 first_index &= ~(REFCOUNTS_PER_SECTOR - 1); 441 last_index = (last_index + REFCOUNTS_PER_SECTOR) 442 & ~(REFCOUNTS_PER_SECTOR - 1); 443 444 size = (last_index - first_index) << REFCOUNT_SHIFT; 445 446 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_UPDATE_PART); 447 ret = bdrv_pwrite_sync(bs->file, 448 refcount_block_offset + (first_index << REFCOUNT_SHIFT), 449 &s->refcount_block_cache[first_index], size); 450 if (ret < 0) { 451 return ret; 452 } 453 454 return 0; 455 } 456 457 /* XXX: cache several refcount block clusters ? */ 458 static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs, 459 int64_t offset, int64_t length, int addend) 460 { 461 BDRVQcowState *s = bs->opaque; 462 int64_t start, last, cluster_offset; 463 int64_t refcount_block_offset = 0; 464 int64_t table_index = -1, old_table_index; 465 int first_index = -1, last_index = -1; 466 int ret; 467 468 #ifdef DEBUG_ALLOC2 469 printf("update_refcount: offset=%" PRId64 " size=%" PRId64 " addend=%d\n", 470 offset, length, addend); 471 #endif 472 if (length < 0) { 473 return -EINVAL; 474 } else if (length == 0) { 475 return 0; 476 } 477 478 start = offset & ~(s->cluster_size - 1); 479 last = (offset + length - 1) & ~(s->cluster_size - 1); 480 for(cluster_offset = start; cluster_offset <= last; 481 cluster_offset += s->cluster_size) 482 { 483 int block_index, refcount; 484 int64_t cluster_index = cluster_offset >> s->cluster_bits; 485 int64_t new_block; 486 487 /* Only write refcount block to disk when we are done with it */ 488 old_table_index = table_index; 489 table_index = cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT); 490 if ((old_table_index >= 0) && (table_index != old_table_index)) { 491 492 ret = write_refcount_block_entries(bs, refcount_block_offset, 493 first_index, last_index); 494 if (ret < 0) { 495 return ret; 496 } 497 498 first_index = -1; 499 last_index = -1; 500 } 501 502 /* Load the refcount block and allocate it if needed */ 503 new_block = alloc_refcount_block(bs, cluster_index); 504 if (new_block < 0) { 505 ret = new_block; 506 goto fail; 507 } 508 refcount_block_offset = new_block; 509 510 /* we can update the count and save it */ 511 block_index = cluster_index & 512 ((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1); 513 if (first_index == -1 || block_index < first_index) { 514 first_index = block_index; 515 } 516 if (block_index > last_index) { 517 last_index = block_index; 518 } 519 520 refcount = be16_to_cpu(s->refcount_block_cache[block_index]); 521 refcount += addend; 522 if (refcount < 0 || refcount > 0xffff) { 523 ret = -EINVAL; 524 goto fail; 525 } 526 if (refcount == 0 && cluster_index < s->free_cluster_index) { 527 s->free_cluster_index = cluster_index; 528 } 529 s->refcount_block_cache[block_index] = cpu_to_be16(refcount); 530 } 531 532 ret = 0; 533 fail: 534 535 /* Write last changed block to disk */ 536 if (refcount_block_offset != 0) { 537 int wret; 538 wret = write_refcount_block_entries(bs, refcount_block_offset, 539 first_index, last_index); 540 if (wret < 0) { 541 return ret < 0 ? ret : wret; 542 } 543 } 544 545 /* 546 * Try do undo any updates if an error is returned (This may succeed in 547 * some cases like ENOSPC for allocating a new refcount block) 548 */ 549 if (ret < 0) { 550 int dummy; 551 dummy = update_refcount(bs, offset, cluster_offset - offset, -addend); 552 } 553 554 return ret; 555 } 556 557 /* 558 * Increases or decreases the refcount of a given cluster by one. 559 * addend must be 1 or -1. 560 * 561 * If the return value is non-negative, it is the new refcount of the cluster. 562 * If it is negative, it is -errno and indicates an error. 563 */ 564 static int update_cluster_refcount(BlockDriverState *bs, 565 int64_t cluster_index, 566 int addend) 567 { 568 BDRVQcowState *s = bs->opaque; 569 int ret; 570 571 ret = update_refcount(bs, cluster_index << s->cluster_bits, 1, addend); 572 if (ret < 0) { 573 return ret; 574 } 575 576 return get_refcount(bs, cluster_index); 577 } 578 579 580 581 /*********************************************************/ 582 /* cluster allocation functions */ 583 584 585 586 /* return < 0 if error */ 587 static int64_t alloc_clusters_noref(BlockDriverState *bs, int64_t size) 588 { 589 BDRVQcowState *s = bs->opaque; 590 int i, nb_clusters, refcount; 591 592 nb_clusters = size_to_clusters(s, size); 593 retry: 594 for(i = 0; i < nb_clusters; i++) { 595 int64_t next_cluster_index = s->free_cluster_index++; 596 refcount = get_refcount(bs, next_cluster_index); 597 598 if (refcount < 0) { 599 return refcount; 600 } else if (refcount != 0) { 601 goto retry; 602 } 603 } 604 #ifdef DEBUG_ALLOC2 605 printf("alloc_clusters: size=%" PRId64 " -> %" PRId64 "\n", 606 size, 607 (s->free_cluster_index - nb_clusters) << s->cluster_bits); 608 #endif 609 return (s->free_cluster_index - nb_clusters) << s->cluster_bits; 610 } 611 612 int64_t qcow2_alloc_clusters(BlockDriverState *bs, int64_t size) 613 { 614 int64_t offset; 615 int ret; 616 617 BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_ALLOC); 618 offset = alloc_clusters_noref(bs, size); 619 if (offset < 0) { 620 return offset; 621 } 622 623 ret = update_refcount(bs, offset, size, 1); 624 if (ret < 0) { 625 return ret; 626 } 627 return offset; 628 } 629 630 /* only used to allocate compressed sectors. We try to allocate 631 contiguous sectors. size must be <= cluster_size */ 632 int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size) 633 { 634 BDRVQcowState *s = bs->opaque; 635 int64_t offset, cluster_offset; 636 int free_in_cluster; 637 638 BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_ALLOC_BYTES); 639 assert(size > 0 && size <= s->cluster_size); 640 if (s->free_byte_offset == 0) { 641 s->free_byte_offset = qcow2_alloc_clusters(bs, s->cluster_size); 642 if (s->free_byte_offset < 0) { 643 return s->free_byte_offset; 644 } 645 } 646 redo: 647 free_in_cluster = s->cluster_size - 648 (s->free_byte_offset & (s->cluster_size - 1)); 649 if (size <= free_in_cluster) { 650 /* enough space in current cluster */ 651 offset = s->free_byte_offset; 652 s->free_byte_offset += size; 653 free_in_cluster -= size; 654 if (free_in_cluster == 0) 655 s->free_byte_offset = 0; 656 if ((offset & (s->cluster_size - 1)) != 0) 657 update_cluster_refcount(bs, offset >> s->cluster_bits, 1); 658 } else { 659 offset = qcow2_alloc_clusters(bs, s->cluster_size); 660 if (offset < 0) { 661 return offset; 662 } 663 cluster_offset = s->free_byte_offset & ~(s->cluster_size - 1); 664 if ((cluster_offset + s->cluster_size) == offset) { 665 /* we are lucky: contiguous data */ 666 offset = s->free_byte_offset; 667 update_cluster_refcount(bs, offset >> s->cluster_bits, 1); 668 s->free_byte_offset += size; 669 } else { 670 s->free_byte_offset = offset; 671 goto redo; 672 } 673 } 674 return offset; 675 } 676 677 void qcow2_free_clusters(BlockDriverState *bs, 678 int64_t offset, int64_t size) 679 { 680 int ret; 681 682 BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_FREE); 683 ret = update_refcount(bs, offset, size, -1); 684 if (ret < 0) { 685 fprintf(stderr, "qcow2_free_clusters failed: %s\n", strerror(-ret)); 686 /* TODO Remember the clusters to free them later and avoid leaking */ 687 } 688 } 689 690 /* 691 * free_any_clusters 692 * 693 * free clusters according to its type: compressed or not 694 * 695 */ 696 697 void qcow2_free_any_clusters(BlockDriverState *bs, 698 uint64_t cluster_offset, int nb_clusters) 699 { 700 BDRVQcowState *s = bs->opaque; 701 702 /* free the cluster */ 703 704 if (cluster_offset & QCOW_OFLAG_COMPRESSED) { 705 int nb_csectors; 706 nb_csectors = ((cluster_offset >> s->csize_shift) & 707 s->csize_mask) + 1; 708 qcow2_free_clusters(bs, 709 (cluster_offset & s->cluster_offset_mask) & ~511, 710 nb_csectors * 512); 711 return; 712 } 713 714 qcow2_free_clusters(bs, cluster_offset, nb_clusters << s->cluster_bits); 715 716 return; 717 } 718 719 720 721 /*********************************************************/ 722 /* snapshots and image creation */ 723 724 725 726 void qcow2_create_refcount_update(QCowCreateState *s, int64_t offset, 727 int64_t size) 728 { 729 int refcount; 730 int64_t start, last, cluster_offset; 731 uint16_t *p; 732 733 start = offset & ~(s->cluster_size - 1); 734 last = (offset + size - 1) & ~(s->cluster_size - 1); 735 for(cluster_offset = start; cluster_offset <= last; 736 cluster_offset += s->cluster_size) { 737 p = &s->refcount_block[cluster_offset >> s->cluster_bits]; 738 refcount = be16_to_cpu(*p); 739 refcount++; 740 *p = cpu_to_be16(refcount); 741 } 742 } 743 744 /* update the refcounts of snapshots and the copied flag */ 745 int qcow2_update_snapshot_refcount(BlockDriverState *bs, 746 int64_t l1_table_offset, int l1_size, int addend) 747 { 748 BDRVQcowState *s = bs->opaque; 749 uint64_t *l1_table, *l2_table, l2_offset, offset, l1_size2, l1_allocated; 750 int64_t old_offset, old_l2_offset; 751 int l2_size, i, j, l1_modified, l2_modified, nb_csectors, refcount; 752 753 qcow2_l2_cache_reset(bs); 754 cache_refcount_updates = 1; 755 756 l2_table = NULL; 757 l1_table = NULL; 758 l1_size2 = l1_size * sizeof(uint64_t); 759 if (l1_table_offset != s->l1_table_offset) { 760 if (l1_size2 != 0) { 761 l1_table = qemu_mallocz(align_offset(l1_size2, 512)); 762 } else { 763 l1_table = NULL; 764 } 765 l1_allocated = 1; 766 if (bdrv_pread(bs->file, l1_table_offset, 767 l1_table, l1_size2) != l1_size2) 768 goto fail; 769 for(i = 0;i < l1_size; i++) 770 be64_to_cpus(&l1_table[i]); 771 } else { 772 assert(l1_size == s->l1_size); 773 l1_table = s->l1_table; 774 l1_allocated = 0; 775 } 776 777 l2_size = s->l2_size * sizeof(uint64_t); 778 l2_table = qemu_malloc(l2_size); 779 l1_modified = 0; 780 for(i = 0; i < l1_size; i++) { 781 l2_offset = l1_table[i]; 782 if (l2_offset) { 783 old_l2_offset = l2_offset; 784 l2_offset &= ~QCOW_OFLAG_COPIED; 785 l2_modified = 0; 786 if (bdrv_pread(bs->file, l2_offset, l2_table, l2_size) != l2_size) 787 goto fail; 788 for(j = 0; j < s->l2_size; j++) { 789 offset = be64_to_cpu(l2_table[j]); 790 if (offset != 0) { 791 old_offset = offset; 792 offset &= ~QCOW_OFLAG_COPIED; 793 if (offset & QCOW_OFLAG_COMPRESSED) { 794 nb_csectors = ((offset >> s->csize_shift) & 795 s->csize_mask) + 1; 796 if (addend != 0) { 797 int ret; 798 ret = update_refcount(bs, 799 (offset & s->cluster_offset_mask) & ~511, 800 nb_csectors * 512, addend); 801 if (ret < 0) { 802 goto fail; 803 } 804 } 805 /* compressed clusters are never modified */ 806 refcount = 2; 807 } else { 808 if (addend != 0) { 809 refcount = update_cluster_refcount(bs, offset >> s->cluster_bits, addend); 810 } else { 811 refcount = get_refcount(bs, offset >> s->cluster_bits); 812 } 813 814 if (refcount < 0) { 815 goto fail; 816 } 817 } 818 819 if (refcount == 1) { 820 offset |= QCOW_OFLAG_COPIED; 821 } 822 if (offset != old_offset) { 823 l2_table[j] = cpu_to_be64(offset); 824 l2_modified = 1; 825 } 826 } 827 } 828 if (l2_modified) { 829 if (bdrv_pwrite_sync(bs->file, 830 l2_offset, l2_table, l2_size) < 0) 831 goto fail; 832 } 833 834 if (addend != 0) { 835 refcount = update_cluster_refcount(bs, l2_offset >> s->cluster_bits, addend); 836 } else { 837 refcount = get_refcount(bs, l2_offset >> s->cluster_bits); 838 } 839 if (refcount < 0) { 840 goto fail; 841 } else if (refcount == 1) { 842 l2_offset |= QCOW_OFLAG_COPIED; 843 } 844 if (l2_offset != old_l2_offset) { 845 l1_table[i] = l2_offset; 846 l1_modified = 1; 847 } 848 } 849 } 850 if (l1_modified) { 851 for(i = 0; i < l1_size; i++) 852 cpu_to_be64s(&l1_table[i]); 853 if (bdrv_pwrite_sync(bs->file, l1_table_offset, l1_table, 854 l1_size2) < 0) 855 goto fail; 856 for(i = 0; i < l1_size; i++) 857 be64_to_cpus(&l1_table[i]); 858 } 859 if (l1_allocated) 860 qemu_free(l1_table); 861 qemu_free(l2_table); 862 cache_refcount_updates = 0; 863 write_refcount_block(bs); 864 return 0; 865 fail: 866 if (l1_allocated) 867 qemu_free(l1_table); 868 qemu_free(l2_table); 869 cache_refcount_updates = 0; 870 write_refcount_block(bs); 871 return -EIO; 872 } 873 874 875 876 877 /*********************************************************/ 878 /* refcount checking functions */ 879 880 881 882 /* 883 * Increases the refcount for a range of clusters in a given refcount table. 884 * This is used to construct a temporary refcount table out of L1 and L2 tables 885 * which can be compared the the refcount table saved in the image. 886 * 887 * Modifies the number of errors in res. 888 */ 889 static void inc_refcounts(BlockDriverState *bs, 890 BdrvCheckResult *res, 891 uint16_t *refcount_table, 892 int refcount_table_size, 893 int64_t offset, int64_t size) 894 { 895 BDRVQcowState *s = bs->opaque; 896 int64_t start, last, cluster_offset; 897 int k; 898 899 if (size <= 0) 900 return; 901 902 start = offset & ~(s->cluster_size - 1); 903 last = (offset + size - 1) & ~(s->cluster_size - 1); 904 for(cluster_offset = start; cluster_offset <= last; 905 cluster_offset += s->cluster_size) { 906 k = cluster_offset >> s->cluster_bits; 907 if (k < 0) { 908 fprintf(stderr, "ERROR: invalid cluster offset=0x%" PRIx64 "\n", 909 cluster_offset); 910 res->corruptions++; 911 } else if (k >= refcount_table_size) { 912 fprintf(stderr, "Warning: cluster offset=0x%" PRIx64 " is after " 913 "the end of the image file, can't properly check refcounts.\n", 914 cluster_offset); 915 res->check_errors++; 916 } else { 917 if (++refcount_table[k] == 0) { 918 fprintf(stderr, "ERROR: overflow cluster offset=0x%" PRIx64 919 "\n", cluster_offset); 920 res->corruptions++; 921 } 922 } 923 } 924 } 925 926 /* 927 * Increases the refcount in the given refcount table for the all clusters 928 * referenced in the L2 table. While doing so, performs some checks on L2 929 * entries. 930 * 931 * Returns the number of errors found by the checks or -errno if an internal 932 * error occurred. 933 */ 934 static int check_refcounts_l2(BlockDriverState *bs, BdrvCheckResult *res, 935 uint16_t *refcount_table, int refcount_table_size, int64_t l2_offset, 936 int check_copied) 937 { 938 BDRVQcowState *s = bs->opaque; 939 uint64_t *l2_table, offset; 940 int i, l2_size, nb_csectors, refcount; 941 942 /* Read L2 table from disk */ 943 l2_size = s->l2_size * sizeof(uint64_t); 944 l2_table = qemu_malloc(l2_size); 945 946 if (bdrv_pread(bs->file, l2_offset, l2_table, l2_size) != l2_size) 947 goto fail; 948 949 /* Do the actual checks */ 950 for(i = 0; i < s->l2_size; i++) { 951 offset = be64_to_cpu(l2_table[i]); 952 if (offset != 0) { 953 if (offset & QCOW_OFLAG_COMPRESSED) { 954 /* Compressed clusters don't have QCOW_OFLAG_COPIED */ 955 if (offset & QCOW_OFLAG_COPIED) { 956 fprintf(stderr, "ERROR: cluster %" PRId64 ": " 957 "copied flag must never be set for compressed " 958 "clusters\n", offset >> s->cluster_bits); 959 offset &= ~QCOW_OFLAG_COPIED; 960 res->corruptions++; 961 } 962 963 /* Mark cluster as used */ 964 nb_csectors = ((offset >> s->csize_shift) & 965 s->csize_mask) + 1; 966 offset &= s->cluster_offset_mask; 967 inc_refcounts(bs, res, refcount_table, refcount_table_size, 968 offset & ~511, nb_csectors * 512); 969 } else { 970 /* QCOW_OFLAG_COPIED must be set iff refcount == 1 */ 971 if (check_copied) { 972 uint64_t entry = offset; 973 offset &= ~QCOW_OFLAG_COPIED; 974 refcount = get_refcount(bs, offset >> s->cluster_bits); 975 if (refcount < 0) { 976 fprintf(stderr, "Can't get refcount for offset %" 977 PRIx64 ": %s\n", entry, strerror(-refcount)); 978 goto fail; 979 } 980 if ((refcount == 1) != ((entry & QCOW_OFLAG_COPIED) != 0)) { 981 fprintf(stderr, "ERROR OFLAG_COPIED: offset=%" 982 PRIx64 " refcount=%d\n", entry, refcount); 983 res->corruptions++; 984 } 985 } 986 987 /* Mark cluster as used */ 988 offset &= ~QCOW_OFLAG_COPIED; 989 inc_refcounts(bs, res, refcount_table,refcount_table_size, 990 offset, s->cluster_size); 991 992 /* Correct offsets are cluster aligned */ 993 if (offset & (s->cluster_size - 1)) { 994 fprintf(stderr, "ERROR offset=%" PRIx64 ": Cluster is not " 995 "properly aligned; L2 entry corrupted.\n", offset); 996 res->corruptions++; 997 } 998 } 999 } 1000 } 1001 1002 qemu_free(l2_table); 1003 return 0; 1004 1005 fail: 1006 fprintf(stderr, "ERROR: I/O error in check_refcounts_l2\n"); 1007 qemu_free(l2_table); 1008 return -EIO; 1009 } 1010 1011 /* 1012 * Increases the refcount for the L1 table, its L2 tables and all referenced 1013 * clusters in the given refcount table. While doing so, performs some checks 1014 * on L1 and L2 entries. 1015 * 1016 * Returns the number of errors found by the checks or -errno if an internal 1017 * error occurred. 1018 */ 1019 static int check_refcounts_l1(BlockDriverState *bs, 1020 BdrvCheckResult *res, 1021 uint16_t *refcount_table, 1022 int refcount_table_size, 1023 int64_t l1_table_offset, int l1_size, 1024 int check_copied) 1025 { 1026 BDRVQcowState *s = bs->opaque; 1027 uint64_t *l1_table, l2_offset, l1_size2; 1028 int i, refcount, ret; 1029 1030 l1_size2 = l1_size * sizeof(uint64_t); 1031 1032 /* Mark L1 table as used */ 1033 inc_refcounts(bs, res, refcount_table, refcount_table_size, 1034 l1_table_offset, l1_size2); 1035 1036 /* Read L1 table entries from disk */ 1037 if (l1_size2 == 0) { 1038 l1_table = NULL; 1039 } else { 1040 l1_table = qemu_malloc(l1_size2); 1041 if (bdrv_pread(bs->file, l1_table_offset, 1042 l1_table, l1_size2) != l1_size2) 1043 goto fail; 1044 for(i = 0;i < l1_size; i++) 1045 be64_to_cpus(&l1_table[i]); 1046 } 1047 1048 /* Do the actual checks */ 1049 for(i = 0; i < l1_size; i++) { 1050 l2_offset = l1_table[i]; 1051 if (l2_offset) { 1052 /* QCOW_OFLAG_COPIED must be set iff refcount == 1 */ 1053 if (check_copied) { 1054 refcount = get_refcount(bs, (l2_offset & ~QCOW_OFLAG_COPIED) 1055 >> s->cluster_bits); 1056 if (refcount < 0) { 1057 fprintf(stderr, "Can't get refcount for l2_offset %" 1058 PRIx64 ": %s\n", l2_offset, strerror(-refcount)); 1059 goto fail; 1060 } 1061 if ((refcount == 1) != ((l2_offset & QCOW_OFLAG_COPIED) != 0)) { 1062 fprintf(stderr, "ERROR OFLAG_COPIED: l2_offset=%" PRIx64 1063 " refcount=%d\n", l2_offset, refcount); 1064 res->corruptions++; 1065 } 1066 } 1067 1068 /* Mark L2 table as used */ 1069 l2_offset &= ~QCOW_OFLAG_COPIED; 1070 inc_refcounts(bs, res, refcount_table, refcount_table_size, 1071 l2_offset, s->cluster_size); 1072 1073 /* L2 tables are cluster aligned */ 1074 if (l2_offset & (s->cluster_size - 1)) { 1075 fprintf(stderr, "ERROR l2_offset=%" PRIx64 ": Table is not " 1076 "cluster aligned; L1 entry corrupted\n", l2_offset); 1077 res->corruptions++; 1078 } 1079 1080 /* Process and check L2 entries */ 1081 ret = check_refcounts_l2(bs, res, refcount_table, 1082 refcount_table_size, l2_offset, check_copied); 1083 if (ret < 0) { 1084 goto fail; 1085 } 1086 } 1087 } 1088 qemu_free(l1_table); 1089 return 0; 1090 1091 fail: 1092 fprintf(stderr, "ERROR: I/O error in check_refcounts_l1\n"); 1093 res->check_errors++; 1094 qemu_free(l1_table); 1095 return -EIO; 1096 } 1097 1098 /* 1099 * Checks an image for refcount consistency. 1100 * 1101 * Returns 0 if no errors are found, the number of errors in case the image is 1102 * detected as corrupted, and -errno when an internal error occured. 1103 */ 1104 int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res) 1105 { 1106 BDRVQcowState *s = bs->opaque; 1107 int64_t size; 1108 int nb_clusters, refcount1, refcount2, i; 1109 QCowSnapshot *sn; 1110 uint16_t *refcount_table; 1111 int ret; 1112 1113 size = bdrv_getlength(bs->file); 1114 nb_clusters = size_to_clusters(s, size); 1115 refcount_table = qemu_mallocz(nb_clusters * sizeof(uint16_t)); 1116 1117 /* header */ 1118 inc_refcounts(bs, res, refcount_table, nb_clusters, 1119 0, s->cluster_size); 1120 1121 /* current L1 table */ 1122 ret = check_refcounts_l1(bs, res, refcount_table, nb_clusters, 1123 s->l1_table_offset, s->l1_size, 1); 1124 if (ret < 0) { 1125 return ret; 1126 } 1127 1128 /* snapshots */ 1129 for(i = 0; i < s->nb_snapshots; i++) { 1130 sn = s->snapshots + i; 1131 ret = check_refcounts_l1(bs, res, refcount_table, nb_clusters, 1132 sn->l1_table_offset, sn->l1_size, 0); 1133 if (ret < 0) { 1134 return ret; 1135 } 1136 } 1137 inc_refcounts(bs, res, refcount_table, nb_clusters, 1138 s->snapshots_offset, s->snapshots_size); 1139 1140 /* refcount data */ 1141 inc_refcounts(bs, res, refcount_table, nb_clusters, 1142 s->refcount_table_offset, 1143 s->refcount_table_size * sizeof(uint64_t)); 1144 1145 for(i = 0; i < s->refcount_table_size; i++) { 1146 uint64_t offset, cluster; 1147 offset = s->refcount_table[i]; 1148 cluster = offset >> s->cluster_bits; 1149 1150 /* Refcount blocks are cluster aligned */ 1151 if (offset & (s->cluster_size - 1)) { 1152 fprintf(stderr, "ERROR refcount block %d is not " 1153 "cluster aligned; refcount table entry corrupted\n", i); 1154 res->corruptions++; 1155 continue; 1156 } 1157 1158 if (cluster >= nb_clusters) { 1159 fprintf(stderr, "ERROR refcount block %d is outside image\n", i); 1160 res->corruptions++; 1161 continue; 1162 } 1163 1164 if (offset != 0) { 1165 inc_refcounts(bs, res, refcount_table, nb_clusters, 1166 offset, s->cluster_size); 1167 if (refcount_table[cluster] != 1) { 1168 fprintf(stderr, "ERROR refcount block %d refcount=%d\n", 1169 i, refcount_table[cluster]); 1170 res->corruptions++; 1171 } 1172 } 1173 } 1174 1175 /* compare ref counts */ 1176 for(i = 0; i < nb_clusters; i++) { 1177 refcount1 = get_refcount(bs, i); 1178 if (refcount1 < 0) { 1179 fprintf(stderr, "Can't get refcount for cluster %d: %s\n", 1180 i, strerror(-refcount1)); 1181 res->check_errors++; 1182 continue; 1183 } 1184 1185 refcount2 = refcount_table[i]; 1186 if (refcount1 != refcount2) { 1187 fprintf(stderr, "%s cluster %d refcount=%d reference=%d\n", 1188 refcount1 < refcount2 ? "ERROR" : "Leaked", 1189 i, refcount1, refcount2); 1190 if (refcount1 < refcount2) { 1191 res->corruptions++; 1192 } else { 1193 res->leaks++; 1194 } 1195 } 1196 } 1197 1198 qemu_free(refcount_table); 1199 1200 return 0; 1201 } 1202 1203
