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/block_int.h" 27 #include "block/qcow2.h" 28 #include "qemu/range.h" 29 #include "qapi/qmp/types.h" 30 31 static int64_t alloc_clusters_noref(BlockDriverState *bs, int64_t size); 32 static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs, 33 int64_t offset, int64_t length, 34 int addend, enum qcow2_discard_type type); 35 36 37 /*********************************************************/ 38 /* refcount handling */ 39 40 int qcow2_refcount_init(BlockDriverState *bs) 41 { 42 BDRVQcowState *s = bs->opaque; 43 int ret, refcount_table_size2, i; 44 45 refcount_table_size2 = s->refcount_table_size * sizeof(uint64_t); 46 s->refcount_table = g_malloc(refcount_table_size2); 47 if (s->refcount_table_size > 0) { 48 BLKDBG_EVENT(bs->file, BLKDBG_REFTABLE_LOAD); 49 ret = bdrv_pread(bs->file, s->refcount_table_offset, 50 s->refcount_table, refcount_table_size2); 51 if (ret != refcount_table_size2) 52 goto fail; 53 for(i = 0; i < s->refcount_table_size; i++) 54 be64_to_cpus(&s->refcount_table[i]); 55 } 56 return 0; 57 fail: 58 return -ENOMEM; 59 } 60 61 void qcow2_refcount_close(BlockDriverState *bs) 62 { 63 BDRVQcowState *s = bs->opaque; 64 g_free(s->refcount_table); 65 } 66 67 68 static int load_refcount_block(BlockDriverState *bs, 69 int64_t refcount_block_offset, 70 void **refcount_block) 71 { 72 BDRVQcowState *s = bs->opaque; 73 int ret; 74 75 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_LOAD); 76 ret = qcow2_cache_get(bs, s->refcount_block_cache, refcount_block_offset, 77 refcount_block); 78 79 return ret; 80 } 81 82 /* 83 * Returns the refcount of the cluster given by its index. Any non-negative 84 * return value is the refcount of the cluster, negative values are -errno 85 * and indicate an error. 86 */ 87 static int get_refcount(BlockDriverState *bs, int64_t cluster_index) 88 { 89 BDRVQcowState *s = bs->opaque; 90 int refcount_table_index, block_index; 91 int64_t refcount_block_offset; 92 int ret; 93 uint16_t *refcount_block; 94 uint16_t refcount; 95 96 refcount_table_index = cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT); 97 if (refcount_table_index >= s->refcount_table_size) 98 return 0; 99 refcount_block_offset = s->refcount_table[refcount_table_index]; 100 if (!refcount_block_offset) 101 return 0; 102 103 ret = qcow2_cache_get(bs, s->refcount_block_cache, refcount_block_offset, 104 (void**) &refcount_block); 105 if (ret < 0) { 106 return ret; 107 } 108 109 block_index = cluster_index & 110 ((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1); 111 refcount = be16_to_cpu(refcount_block[block_index]); 112 113 ret = qcow2_cache_put(bs, s->refcount_block_cache, 114 (void**) &refcount_block); 115 if (ret < 0) { 116 return ret; 117 } 118 119 return refcount; 120 } 121 122 /* 123 * Rounds the refcount table size up to avoid growing the table for each single 124 * refcount block that is allocated. 125 */ 126 static unsigned int next_refcount_table_size(BDRVQcowState *s, 127 unsigned int min_size) 128 { 129 unsigned int min_clusters = (min_size >> (s->cluster_bits - 3)) + 1; 130 unsigned int refcount_table_clusters = 131 MAX(1, s->refcount_table_size >> (s->cluster_bits - 3)); 132 133 while (min_clusters > refcount_table_clusters) { 134 refcount_table_clusters = (refcount_table_clusters * 3 + 1) / 2; 135 } 136 137 return refcount_table_clusters << (s->cluster_bits - 3); 138 } 139 140 141 /* Checks if two offsets are described by the same refcount block */ 142 static int in_same_refcount_block(BDRVQcowState *s, uint64_t offset_a, 143 uint64_t offset_b) 144 { 145 uint64_t block_a = offset_a >> (2 * s->cluster_bits - REFCOUNT_SHIFT); 146 uint64_t block_b = offset_b >> (2 * s->cluster_bits - REFCOUNT_SHIFT); 147 148 return (block_a == block_b); 149 } 150 151 /* 152 * Loads a refcount block. If it doesn't exist yet, it is allocated first 153 * (including growing the refcount table if needed). 154 * 155 * Returns 0 on success or -errno in error case 156 */ 157 static int alloc_refcount_block(BlockDriverState *bs, 158 int64_t cluster_index, uint16_t **refcount_block) 159 { 160 BDRVQcowState *s = bs->opaque; 161 unsigned int refcount_table_index; 162 int ret; 163 164 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC); 165 166 /* Find the refcount block for the given cluster */ 167 refcount_table_index = cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT); 168 169 if (refcount_table_index < s->refcount_table_size) { 170 171 uint64_t refcount_block_offset = 172 s->refcount_table[refcount_table_index] & REFT_OFFSET_MASK; 173 174 /* If it's already there, we're done */ 175 if (refcount_block_offset) { 176 return load_refcount_block(bs, refcount_block_offset, 177 (void**) refcount_block); 178 } 179 } 180 181 /* 182 * If we came here, we need to allocate something. Something is at least 183 * a cluster for the new refcount block. It may also include a new refcount 184 * table if the old refcount table is too small. 185 * 186 * Note that allocating clusters here needs some special care: 187 * 188 * - We can't use the normal qcow2_alloc_clusters(), it would try to 189 * increase the refcount and very likely we would end up with an endless 190 * recursion. Instead we must place the refcount blocks in a way that 191 * they can describe them themselves. 192 * 193 * - We need to consider that at this point we are inside update_refcounts 194 * and doing the initial refcount increase. This means that some clusters 195 * have already been allocated by the caller, but their refcount isn't 196 * accurate yet. free_cluster_index tells us where this allocation ends 197 * as long as we don't overwrite it by freeing clusters. 198 * 199 * - alloc_clusters_noref and qcow2_free_clusters may load a different 200 * refcount block into the cache 201 */ 202 203 *refcount_block = NULL; 204 205 /* We write to the refcount table, so we might depend on L2 tables */ 206 ret = qcow2_cache_flush(bs, s->l2_table_cache); 207 if (ret < 0) { 208 return ret; 209 } 210 211 /* Allocate the refcount block itself and mark it as used */ 212 int64_t new_block = alloc_clusters_noref(bs, s->cluster_size); 213 if (new_block < 0) { 214 return new_block; 215 } 216 217 #ifdef DEBUG_ALLOC2 218 fprintf(stderr, "qcow2: Allocate refcount block %d for %" PRIx64 219 " at %" PRIx64 "\n", 220 refcount_table_index, cluster_index << s->cluster_bits, new_block); 221 #endif 222 223 if (in_same_refcount_block(s, new_block, cluster_index << s->cluster_bits)) { 224 /* Zero the new refcount block before updating it */ 225 ret = qcow2_cache_get_empty(bs, s->refcount_block_cache, new_block, 226 (void**) refcount_block); 227 if (ret < 0) { 228 goto fail_block; 229 } 230 231 memset(*refcount_block, 0, s->cluster_size); 232 233 /* The block describes itself, need to update the cache */ 234 int block_index = (new_block >> s->cluster_bits) & 235 ((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1); 236 (*refcount_block)[block_index] = cpu_to_be16(1); 237 } else { 238 /* Described somewhere else. This can recurse at most twice before we 239 * arrive at a block that describes itself. */ 240 ret = update_refcount(bs, new_block, s->cluster_size, 1, 241 QCOW2_DISCARD_NEVER); 242 if (ret < 0) { 243 goto fail_block; 244 } 245 246 ret = qcow2_cache_flush(bs, s->refcount_block_cache); 247 if (ret < 0) { 248 goto fail_block; 249 } 250 251 /* Initialize the new refcount block only after updating its refcount, 252 * update_refcount uses the refcount cache itself */ 253 ret = qcow2_cache_get_empty(bs, s->refcount_block_cache, new_block, 254 (void**) refcount_block); 255 if (ret < 0) { 256 goto fail_block; 257 } 258 259 memset(*refcount_block, 0, s->cluster_size); 260 } 261 262 /* Now the new refcount block needs to be written to disk */ 263 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_WRITE); 264 qcow2_cache_entry_mark_dirty(s->refcount_block_cache, *refcount_block); 265 ret = qcow2_cache_flush(bs, s->refcount_block_cache); 266 if (ret < 0) { 267 goto fail_block; 268 } 269 270 /* If the refcount table is big enough, just hook the block up there */ 271 if (refcount_table_index < s->refcount_table_size) { 272 uint64_t data64 = cpu_to_be64(new_block); 273 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_HOOKUP); 274 ret = bdrv_pwrite_sync(bs->file, 275 s->refcount_table_offset + refcount_table_index * sizeof(uint64_t), 276 &data64, sizeof(data64)); 277 if (ret < 0) { 278 goto fail_block; 279 } 280 281 s->refcount_table[refcount_table_index] = new_block; 282 return 0; 283 } 284 285 ret = qcow2_cache_put(bs, s->refcount_block_cache, (void**) refcount_block); 286 if (ret < 0) { 287 goto fail_block; 288 } 289 290 /* 291 * If we come here, we need to grow the refcount table. Again, a new 292 * refcount table needs some space and we can't simply allocate to avoid 293 * endless recursion. 294 * 295 * Therefore let's grab new refcount blocks at the end of the image, which 296 * will describe themselves and the new refcount table. This way we can 297 * reference them only in the new table and do the switch to the new 298 * refcount table at once without producing an inconsistent state in 299 * between. 300 */ 301 BLKDBG_EVENT(bs->file, BLKDBG_REFTABLE_GROW); 302 303 /* Calculate the number of refcount blocks needed so far */ 304 uint64_t refcount_block_clusters = 1 << (s->cluster_bits - REFCOUNT_SHIFT); 305 uint64_t blocks_used = (s->free_cluster_index + 306 refcount_block_clusters - 1) / refcount_block_clusters; 307 308 /* And now we need at least one block more for the new metadata */ 309 uint64_t table_size = next_refcount_table_size(s, blocks_used + 1); 310 uint64_t last_table_size; 311 uint64_t blocks_clusters; 312 do { 313 uint64_t table_clusters = 314 size_to_clusters(s, table_size * sizeof(uint64_t)); 315 blocks_clusters = 1 + 316 ((table_clusters + refcount_block_clusters - 1) 317 / refcount_block_clusters); 318 uint64_t meta_clusters = table_clusters + blocks_clusters; 319 320 last_table_size = table_size; 321 table_size = next_refcount_table_size(s, blocks_used + 322 ((meta_clusters + refcount_block_clusters - 1) 323 / refcount_block_clusters)); 324 325 } while (last_table_size != table_size); 326 327 #ifdef DEBUG_ALLOC2 328 fprintf(stderr, "qcow2: Grow refcount table %" PRId32 " => %" PRId64 "\n", 329 s->refcount_table_size, table_size); 330 #endif 331 332 /* Create the new refcount table and blocks */ 333 uint64_t meta_offset = (blocks_used * refcount_block_clusters) * 334 s->cluster_size; 335 uint64_t table_offset = meta_offset + blocks_clusters * s->cluster_size; 336 uint16_t *new_blocks = g_malloc0(blocks_clusters * s->cluster_size); 337 uint64_t *new_table = g_malloc0(table_size * sizeof(uint64_t)); 338 339 assert(meta_offset >= (s->free_cluster_index * s->cluster_size)); 340 341 /* Fill the new refcount table */ 342 memcpy(new_table, s->refcount_table, 343 s->refcount_table_size * sizeof(uint64_t)); 344 new_table[refcount_table_index] = new_block; 345 346 int i; 347 for (i = 0; i < blocks_clusters; i++) { 348 new_table[blocks_used + i] = meta_offset + (i * s->cluster_size); 349 } 350 351 /* Fill the refcount blocks */ 352 uint64_t table_clusters = size_to_clusters(s, table_size * sizeof(uint64_t)); 353 int block = 0; 354 for (i = 0; i < table_clusters + blocks_clusters; i++) { 355 new_blocks[block++] = cpu_to_be16(1); 356 } 357 358 /* Write refcount blocks to disk */ 359 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_WRITE_BLOCKS); 360 ret = bdrv_pwrite_sync(bs->file, meta_offset, new_blocks, 361 blocks_clusters * s->cluster_size); 362 g_free(new_blocks); 363 if (ret < 0) { 364 goto fail_table; 365 } 366 367 /* Write refcount table to disk */ 368 for(i = 0; i < table_size; i++) { 369 cpu_to_be64s(&new_table[i]); 370 } 371 372 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_WRITE_TABLE); 373 ret = bdrv_pwrite_sync(bs->file, table_offset, new_table, 374 table_size * sizeof(uint64_t)); 375 if (ret < 0) { 376 goto fail_table; 377 } 378 379 for(i = 0; i < table_size; i++) { 380 be64_to_cpus(&new_table[i]); 381 } 382 383 /* Hook up the new refcount table in the qcow2 header */ 384 uint8_t data[12]; 385 cpu_to_be64w((uint64_t*)data, table_offset); 386 cpu_to_be32w((uint32_t*)(data + 8), table_clusters); 387 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_SWITCH_TABLE); 388 ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, refcount_table_offset), 389 data, sizeof(data)); 390 if (ret < 0) { 391 goto fail_table; 392 } 393 394 /* And switch it in memory */ 395 uint64_t old_table_offset = s->refcount_table_offset; 396 uint64_t old_table_size = s->refcount_table_size; 397 398 g_free(s->refcount_table); 399 s->refcount_table = new_table; 400 s->refcount_table_size = table_size; 401 s->refcount_table_offset = table_offset; 402 403 /* Free old table. Remember, we must not change free_cluster_index */ 404 uint64_t old_free_cluster_index = s->free_cluster_index; 405 qcow2_free_clusters(bs, old_table_offset, old_table_size * sizeof(uint64_t), 406 QCOW2_DISCARD_OTHER); 407 s->free_cluster_index = old_free_cluster_index; 408 409 ret = load_refcount_block(bs, new_block, (void**) refcount_block); 410 if (ret < 0) { 411 return ret; 412 } 413 414 return 0; 415 416 fail_table: 417 g_free(new_table); 418 fail_block: 419 if (*refcount_block != NULL) { 420 qcow2_cache_put(bs, s->refcount_block_cache, (void**) refcount_block); 421 } 422 return ret; 423 } 424 425 void qcow2_process_discards(BlockDriverState *bs, int ret) 426 { 427 BDRVQcowState *s = bs->opaque; 428 Qcow2DiscardRegion *d, *next; 429 430 QTAILQ_FOREACH_SAFE(d, &s->discards, next, next) { 431 QTAILQ_REMOVE(&s->discards, d, next); 432 433 /* Discard is optional, ignore the return value */ 434 if (ret >= 0) { 435 bdrv_discard(bs->file, 436 d->offset >> BDRV_SECTOR_BITS, 437 d->bytes >> BDRV_SECTOR_BITS); 438 } 439 440 g_free(d); 441 } 442 } 443 444 static void update_refcount_discard(BlockDriverState *bs, 445 uint64_t offset, uint64_t length) 446 { 447 BDRVQcowState *s = bs->opaque; 448 Qcow2DiscardRegion *d, *p, *next; 449 450 QTAILQ_FOREACH(d, &s->discards, next) { 451 uint64_t new_start = MIN(offset, d->offset); 452 uint64_t new_end = MAX(offset + length, d->offset + d->bytes); 453 454 if (new_end - new_start <= length + d->bytes) { 455 /* There can't be any overlap, areas ending up here have no 456 * references any more and therefore shouldn't get freed another 457 * time. */ 458 assert(d->bytes + length == new_end - new_start); 459 d->offset = new_start; 460 d->bytes = new_end - new_start; 461 goto found; 462 } 463 } 464 465 d = g_malloc(sizeof(*d)); 466 *d = (Qcow2DiscardRegion) { 467 .bs = bs, 468 .offset = offset, 469 .bytes = length, 470 }; 471 QTAILQ_INSERT_TAIL(&s->discards, d, next); 472 473 found: 474 /* Merge discard requests if they are adjacent now */ 475 QTAILQ_FOREACH_SAFE(p, &s->discards, next, next) { 476 if (p == d 477 || p->offset > d->offset + d->bytes 478 || d->offset > p->offset + p->bytes) 479 { 480 continue; 481 } 482 483 /* Still no overlap possible */ 484 assert(p->offset == d->offset + d->bytes 485 || d->offset == p->offset + p->bytes); 486 487 QTAILQ_REMOVE(&s->discards, p, next); 488 d->offset = MIN(d->offset, p->offset); 489 d->bytes += p->bytes; 490 } 491 } 492 493 /* XXX: cache several refcount block clusters ? */ 494 static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs, 495 int64_t offset, int64_t length, int addend, enum qcow2_discard_type type) 496 { 497 BDRVQcowState *s = bs->opaque; 498 int64_t start, last, cluster_offset; 499 uint16_t *refcount_block = NULL; 500 int64_t old_table_index = -1; 501 int ret; 502 503 #ifdef DEBUG_ALLOC2 504 fprintf(stderr, "update_refcount: offset=%" PRId64 " size=%" PRId64 " addend=%d\n", 505 offset, length, addend); 506 #endif 507 if (length < 0) { 508 return -EINVAL; 509 } else if (length == 0) { 510 return 0; 511 } 512 513 if (addend < 0) { 514 qcow2_cache_set_dependency(bs, s->refcount_block_cache, 515 s->l2_table_cache); 516 } 517 518 start = start_of_cluster(s, offset); 519 last = start_of_cluster(s, offset + length - 1); 520 for(cluster_offset = start; cluster_offset <= last; 521 cluster_offset += s->cluster_size) 522 { 523 int block_index, refcount; 524 int64_t cluster_index = cluster_offset >> s->cluster_bits; 525 int64_t table_index = 526 cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT); 527 528 /* Load the refcount block and allocate it if needed */ 529 if (table_index != old_table_index) { 530 if (refcount_block) { 531 ret = qcow2_cache_put(bs, s->refcount_block_cache, 532 (void**) &refcount_block); 533 if (ret < 0) { 534 goto fail; 535 } 536 } 537 538 ret = alloc_refcount_block(bs, cluster_index, &refcount_block); 539 if (ret < 0) { 540 goto fail; 541 } 542 } 543 old_table_index = table_index; 544 545 qcow2_cache_entry_mark_dirty(s->refcount_block_cache, refcount_block); 546 547 /* we can update the count and save it */ 548 block_index = cluster_index & 549 ((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1); 550 551 refcount = be16_to_cpu(refcount_block[block_index]); 552 refcount += addend; 553 if (refcount < 0 || refcount > 0xffff) { 554 ret = -EINVAL; 555 goto fail; 556 } 557 if (refcount == 0 && cluster_index < s->free_cluster_index) { 558 s->free_cluster_index = cluster_index; 559 } 560 refcount_block[block_index] = cpu_to_be16(refcount); 561 562 if (refcount == 0 && s->discard_passthrough[type]) { 563 update_refcount_discard(bs, cluster_offset, s->cluster_size); 564 } 565 } 566 567 ret = 0; 568 fail: 569 if (!s->cache_discards) { 570 qcow2_process_discards(bs, ret); 571 } 572 573 /* Write last changed block to disk */ 574 if (refcount_block) { 575 int wret; 576 wret = qcow2_cache_put(bs, s->refcount_block_cache, 577 (void**) &refcount_block); 578 if (wret < 0) { 579 return ret < 0 ? ret : wret; 580 } 581 } 582 583 /* 584 * Try do undo any updates if an error is returned (This may succeed in 585 * some cases like ENOSPC for allocating a new refcount block) 586 */ 587 if (ret < 0) { 588 int dummy; 589 dummy = update_refcount(bs, offset, cluster_offset - offset, -addend, 590 QCOW2_DISCARD_NEVER); 591 (void)dummy; 592 } 593 594 return ret; 595 } 596 597 /* 598 * Increases or decreases the refcount of a given cluster by one. 599 * addend must be 1 or -1. 600 * 601 * If the return value is non-negative, it is the new refcount of the cluster. 602 * If it is negative, it is -errno and indicates an error. 603 */ 604 int qcow2_update_cluster_refcount(BlockDriverState *bs, 605 int64_t cluster_index, 606 int addend, 607 enum qcow2_discard_type type) 608 { 609 BDRVQcowState *s = bs->opaque; 610 int ret; 611 612 ret = update_refcount(bs, cluster_index << s->cluster_bits, 1, addend, 613 type); 614 if (ret < 0) { 615 return ret; 616 } 617 618 return get_refcount(bs, cluster_index); 619 } 620 621 622 623 /*********************************************************/ 624 /* cluster allocation functions */ 625 626 627 628 /* return < 0 if error */ 629 static int64_t alloc_clusters_noref(BlockDriverState *bs, int64_t size) 630 { 631 BDRVQcowState *s = bs->opaque; 632 int i, nb_clusters, refcount; 633 634 nb_clusters = size_to_clusters(s, size); 635 retry: 636 for(i = 0; i < nb_clusters; i++) { 637 int64_t next_cluster_index = s->free_cluster_index++; 638 refcount = get_refcount(bs, next_cluster_index); 639 640 if (refcount < 0) { 641 return refcount; 642 } else if (refcount != 0) { 643 goto retry; 644 } 645 } 646 #ifdef DEBUG_ALLOC2 647 fprintf(stderr, "alloc_clusters: size=%" PRId64 " -> %" PRId64 "\n", 648 size, 649 (s->free_cluster_index - nb_clusters) << s->cluster_bits); 650 #endif 651 return (s->free_cluster_index - nb_clusters) << s->cluster_bits; 652 } 653 654 int64_t qcow2_alloc_clusters(BlockDriverState *bs, int64_t size) 655 { 656 int64_t offset; 657 int ret; 658 659 BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_ALLOC); 660 offset = alloc_clusters_noref(bs, size); 661 if (offset < 0) { 662 return offset; 663 } 664 665 ret = update_refcount(bs, offset, size, 1, QCOW2_DISCARD_NEVER); 666 if (ret < 0) { 667 return ret; 668 } 669 670 return offset; 671 } 672 673 int qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t offset, 674 int nb_clusters) 675 { 676 BDRVQcowState *s = bs->opaque; 677 uint64_t cluster_index; 678 uint64_t old_free_cluster_index; 679 uint64_t i; 680 int refcount, ret; 681 682 assert(nb_clusters >= 0); 683 if (nb_clusters == 0) { 684 return 0; 685 } 686 687 /* Check how many clusters there are free */ 688 cluster_index = offset >> s->cluster_bits; 689 for(i = 0; i < nb_clusters; i++) { 690 refcount = get_refcount(bs, cluster_index++); 691 692 if (refcount < 0) { 693 return refcount; 694 } else if (refcount != 0) { 695 break; 696 } 697 } 698 699 /* And then allocate them */ 700 old_free_cluster_index = s->free_cluster_index; 701 s->free_cluster_index = cluster_index + i; 702 703 ret = update_refcount(bs, offset, i << s->cluster_bits, 1, 704 QCOW2_DISCARD_NEVER); 705 if (ret < 0) { 706 return ret; 707 } 708 709 s->free_cluster_index = old_free_cluster_index; 710 711 return i; 712 } 713 714 /* only used to allocate compressed sectors. We try to allocate 715 contiguous sectors. size must be <= cluster_size */ 716 int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size) 717 { 718 BDRVQcowState *s = bs->opaque; 719 int64_t offset, cluster_offset; 720 int free_in_cluster; 721 722 BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_ALLOC_BYTES); 723 assert(size > 0 && size <= s->cluster_size); 724 if (s->free_byte_offset == 0) { 725 offset = qcow2_alloc_clusters(bs, s->cluster_size); 726 if (offset < 0) { 727 return offset; 728 } 729 s->free_byte_offset = offset; 730 } 731 redo: 732 free_in_cluster = s->cluster_size - 733 offset_into_cluster(s, s->free_byte_offset); 734 if (size <= free_in_cluster) { 735 /* enough space in current cluster */ 736 offset = s->free_byte_offset; 737 s->free_byte_offset += size; 738 free_in_cluster -= size; 739 if (free_in_cluster == 0) 740 s->free_byte_offset = 0; 741 if (offset_into_cluster(s, offset) != 0) 742 qcow2_update_cluster_refcount(bs, offset >> s->cluster_bits, 1, 743 QCOW2_DISCARD_NEVER); 744 } else { 745 offset = qcow2_alloc_clusters(bs, s->cluster_size); 746 if (offset < 0) { 747 return offset; 748 } 749 cluster_offset = start_of_cluster(s, s->free_byte_offset); 750 if ((cluster_offset + s->cluster_size) == offset) { 751 /* we are lucky: contiguous data */ 752 offset = s->free_byte_offset; 753 qcow2_update_cluster_refcount(bs, offset >> s->cluster_bits, 1, 754 QCOW2_DISCARD_NEVER); 755 s->free_byte_offset += size; 756 } else { 757 s->free_byte_offset = offset; 758 goto redo; 759 } 760 } 761 762 /* The cluster refcount was incremented, either by qcow2_alloc_clusters() 763 * or explicitly by qcow2_update_cluster_refcount(). Refcount blocks must 764 * be flushed before the caller's L2 table updates. 765 */ 766 qcow2_cache_set_dependency(bs, s->l2_table_cache, s->refcount_block_cache); 767 return offset; 768 } 769 770 void qcow2_free_clusters(BlockDriverState *bs, 771 int64_t offset, int64_t size, 772 enum qcow2_discard_type type) 773 { 774 int ret; 775 776 BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_FREE); 777 ret = update_refcount(bs, offset, size, -1, type); 778 if (ret < 0) { 779 fprintf(stderr, "qcow2_free_clusters failed: %s\n", strerror(-ret)); 780 /* TODO Remember the clusters to free them later and avoid leaking */ 781 } 782 } 783 784 /* 785 * Free a cluster using its L2 entry (handles clusters of all types, e.g. 786 * normal cluster, compressed cluster, etc.) 787 */ 788 void qcow2_free_any_clusters(BlockDriverState *bs, uint64_t l2_entry, 789 int nb_clusters, enum qcow2_discard_type type) 790 { 791 BDRVQcowState *s = bs->opaque; 792 793 switch (qcow2_get_cluster_type(l2_entry)) { 794 case QCOW2_CLUSTER_COMPRESSED: 795 { 796 int nb_csectors; 797 nb_csectors = ((l2_entry >> s->csize_shift) & 798 s->csize_mask) + 1; 799 qcow2_free_clusters(bs, 800 (l2_entry & s->cluster_offset_mask) & ~511, 801 nb_csectors * 512, type); 802 } 803 break; 804 case QCOW2_CLUSTER_NORMAL: 805 case QCOW2_CLUSTER_ZERO: 806 if (l2_entry & L2E_OFFSET_MASK) { 807 qcow2_free_clusters(bs, l2_entry & L2E_OFFSET_MASK, 808 nb_clusters << s->cluster_bits, type); 809 } 810 break; 811 case QCOW2_CLUSTER_UNALLOCATED: 812 break; 813 default: 814 abort(); 815 } 816 } 817 818 819 820 /*********************************************************/ 821 /* snapshots and image creation */ 822 823 824 825 /* update the refcounts of snapshots and the copied flag */ 826 int qcow2_update_snapshot_refcount(BlockDriverState *bs, 827 int64_t l1_table_offset, int l1_size, int addend) 828 { 829 BDRVQcowState *s = bs->opaque; 830 uint64_t *l1_table, *l2_table, l2_offset, offset, l1_size2, l1_allocated; 831 int64_t old_offset, old_l2_offset; 832 int i, j, l1_modified = 0, nb_csectors, refcount; 833 int ret; 834 835 l2_table = NULL; 836 l1_table = NULL; 837 l1_size2 = l1_size * sizeof(uint64_t); 838 839 s->cache_discards = true; 840 841 /* WARNING: qcow2_snapshot_goto relies on this function not using the 842 * l1_table_offset when it is the current s->l1_table_offset! Be careful 843 * when changing this! */ 844 if (l1_table_offset != s->l1_table_offset) { 845 l1_table = g_malloc0(align_offset(l1_size2, 512)); 846 l1_allocated = 1; 847 848 ret = bdrv_pread(bs->file, l1_table_offset, l1_table, l1_size2); 849 if (ret < 0) { 850 goto fail; 851 } 852 853 for(i = 0;i < l1_size; i++) 854 be64_to_cpus(&l1_table[i]); 855 } else { 856 assert(l1_size == s->l1_size); 857 l1_table = s->l1_table; 858 l1_allocated = 0; 859 } 860 861 for(i = 0; i < l1_size; i++) { 862 l2_offset = l1_table[i]; 863 if (l2_offset) { 864 old_l2_offset = l2_offset; 865 l2_offset &= L1E_OFFSET_MASK; 866 867 ret = qcow2_cache_get(bs, s->l2_table_cache, l2_offset, 868 (void**) &l2_table); 869 if (ret < 0) { 870 goto fail; 871 } 872 873 for(j = 0; j < s->l2_size; j++) { 874 uint64_t cluster_index; 875 876 offset = be64_to_cpu(l2_table[j]); 877 old_offset = offset; 878 offset &= ~QCOW_OFLAG_COPIED; 879 880 switch (qcow2_get_cluster_type(offset)) { 881 case QCOW2_CLUSTER_COMPRESSED: 882 nb_csectors = ((offset >> s->csize_shift) & 883 s->csize_mask) + 1; 884 if (addend != 0) { 885 ret = update_refcount(bs, 886 (offset & s->cluster_offset_mask) & ~511, 887 nb_csectors * 512, addend, 888 QCOW2_DISCARD_SNAPSHOT); 889 if (ret < 0) { 890 goto fail; 891 } 892 } 893 /* compressed clusters are never modified */ 894 refcount = 2; 895 break; 896 897 case QCOW2_CLUSTER_NORMAL: 898 case QCOW2_CLUSTER_ZERO: 899 cluster_index = (offset & L2E_OFFSET_MASK) >> s->cluster_bits; 900 if (!cluster_index) { 901 /* unallocated */ 902 refcount = 0; 903 break; 904 } 905 if (addend != 0) { 906 refcount = qcow2_update_cluster_refcount(bs, 907 cluster_index, addend, 908 QCOW2_DISCARD_SNAPSHOT); 909 } else { 910 refcount = get_refcount(bs, cluster_index); 911 } 912 913 if (refcount < 0) { 914 ret = refcount; 915 goto fail; 916 } 917 break; 918 919 case QCOW2_CLUSTER_UNALLOCATED: 920 refcount = 0; 921 break; 922 923 default: 924 abort(); 925 } 926 927 if (refcount == 1) { 928 offset |= QCOW_OFLAG_COPIED; 929 } 930 if (offset != old_offset) { 931 if (addend > 0) { 932 qcow2_cache_set_dependency(bs, s->l2_table_cache, 933 s->refcount_block_cache); 934 } 935 l2_table[j] = cpu_to_be64(offset); 936 qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table); 937 } 938 } 939 940 ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); 941 if (ret < 0) { 942 goto fail; 943 } 944 945 946 if (addend != 0) { 947 refcount = qcow2_update_cluster_refcount(bs, l2_offset >> 948 s->cluster_bits, addend, QCOW2_DISCARD_SNAPSHOT); 949 } else { 950 refcount = get_refcount(bs, l2_offset >> s->cluster_bits); 951 } 952 if (refcount < 0) { 953 ret = refcount; 954 goto fail; 955 } else if (refcount == 1) { 956 l2_offset |= QCOW_OFLAG_COPIED; 957 } 958 if (l2_offset != old_l2_offset) { 959 l1_table[i] = l2_offset; 960 l1_modified = 1; 961 } 962 } 963 } 964 965 ret = bdrv_flush(bs); 966 fail: 967 if (l2_table) { 968 qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); 969 } 970 971 s->cache_discards = false; 972 qcow2_process_discards(bs, ret); 973 974 /* Update L1 only if it isn't deleted anyway (addend = -1) */ 975 if (ret == 0 && addend >= 0 && l1_modified) { 976 for (i = 0; i < l1_size; i++) { 977 cpu_to_be64s(&l1_table[i]); 978 } 979 980 ret = bdrv_pwrite_sync(bs->file, l1_table_offset, l1_table, l1_size2); 981 982 for (i = 0; i < l1_size; i++) { 983 be64_to_cpus(&l1_table[i]); 984 } 985 } 986 if (l1_allocated) 987 g_free(l1_table); 988 return ret; 989 } 990 991 992 993 994 /*********************************************************/ 995 /* refcount checking functions */ 996 997 998 999 /* 1000 * Increases the refcount for a range of clusters in a given refcount table. 1001 * This is used to construct a temporary refcount table out of L1 and L2 tables 1002 * which can be compared the the refcount table saved in the image. 1003 * 1004 * Modifies the number of errors in res. 1005 */ 1006 static void inc_refcounts(BlockDriverState *bs, 1007 BdrvCheckResult *res, 1008 uint16_t *refcount_table, 1009 int refcount_table_size, 1010 int64_t offset, int64_t size) 1011 { 1012 BDRVQcowState *s = bs->opaque; 1013 int64_t start, last, cluster_offset; 1014 int k; 1015 1016 if (size <= 0) 1017 return; 1018 1019 start = start_of_cluster(s, offset); 1020 last = start_of_cluster(s, offset + size - 1); 1021 for(cluster_offset = start; cluster_offset <= last; 1022 cluster_offset += s->cluster_size) { 1023 k = cluster_offset >> s->cluster_bits; 1024 if (k < 0) { 1025 fprintf(stderr, "ERROR: invalid cluster offset=0x%" PRIx64 "\n", 1026 cluster_offset); 1027 res->corruptions++; 1028 } else if (k >= refcount_table_size) { 1029 fprintf(stderr, "Warning: cluster offset=0x%" PRIx64 " is after " 1030 "the end of the image file, can't properly check refcounts.\n", 1031 cluster_offset); 1032 res->check_errors++; 1033 } else { 1034 if (++refcount_table[k] == 0) { 1035 fprintf(stderr, "ERROR: overflow cluster offset=0x%" PRIx64 1036 "\n", cluster_offset); 1037 res->corruptions++; 1038 } 1039 } 1040 } 1041 } 1042 1043 /* Flags for check_refcounts_l1() and check_refcounts_l2() */ 1044 enum { 1045 CHECK_FRAG_INFO = 0x2, /* update BlockFragInfo counters */ 1046 }; 1047 1048 /* 1049 * Increases the refcount in the given refcount table for the all clusters 1050 * referenced in the L2 table. While doing so, performs some checks on L2 1051 * entries. 1052 * 1053 * Returns the number of errors found by the checks or -errno if an internal 1054 * error occurred. 1055 */ 1056 static int check_refcounts_l2(BlockDriverState *bs, BdrvCheckResult *res, 1057 uint16_t *refcount_table, int refcount_table_size, int64_t l2_offset, 1058 int flags) 1059 { 1060 BDRVQcowState *s = bs->opaque; 1061 uint64_t *l2_table, l2_entry; 1062 uint64_t next_contiguous_offset = 0; 1063 int i, l2_size, nb_csectors; 1064 1065 /* Read L2 table from disk */ 1066 l2_size = s->l2_size * sizeof(uint64_t); 1067 l2_table = g_malloc(l2_size); 1068 1069 if (bdrv_pread(bs->file, l2_offset, l2_table, l2_size) != l2_size) 1070 goto fail; 1071 1072 /* Do the actual checks */ 1073 for(i = 0; i < s->l2_size; i++) { 1074 l2_entry = be64_to_cpu(l2_table[i]); 1075 1076 switch (qcow2_get_cluster_type(l2_entry)) { 1077 case QCOW2_CLUSTER_COMPRESSED: 1078 /* Compressed clusters don't have QCOW_OFLAG_COPIED */ 1079 if (l2_entry & QCOW_OFLAG_COPIED) { 1080 fprintf(stderr, "ERROR: cluster %" PRId64 ": " 1081 "copied flag must never be set for compressed " 1082 "clusters\n", l2_entry >> s->cluster_bits); 1083 l2_entry &= ~QCOW_OFLAG_COPIED; 1084 res->corruptions++; 1085 } 1086 1087 /* Mark cluster as used */ 1088 nb_csectors = ((l2_entry >> s->csize_shift) & 1089 s->csize_mask) + 1; 1090 l2_entry &= s->cluster_offset_mask; 1091 inc_refcounts(bs, res, refcount_table, refcount_table_size, 1092 l2_entry & ~511, nb_csectors * 512); 1093 1094 if (flags & CHECK_FRAG_INFO) { 1095 res->bfi.allocated_clusters++; 1096 res->bfi.compressed_clusters++; 1097 1098 /* Compressed clusters are fragmented by nature. Since they 1099 * take up sub-sector space but we only have sector granularity 1100 * I/O we need to re-read the same sectors even for adjacent 1101 * compressed clusters. 1102 */ 1103 res->bfi.fragmented_clusters++; 1104 } 1105 break; 1106 1107 case QCOW2_CLUSTER_ZERO: 1108 if ((l2_entry & L2E_OFFSET_MASK) == 0) { 1109 break; 1110 } 1111 /* fall through */ 1112 1113 case QCOW2_CLUSTER_NORMAL: 1114 { 1115 uint64_t offset = l2_entry & L2E_OFFSET_MASK; 1116 1117 if (flags & CHECK_FRAG_INFO) { 1118 res->bfi.allocated_clusters++; 1119 if (next_contiguous_offset && 1120 offset != next_contiguous_offset) { 1121 res->bfi.fragmented_clusters++; 1122 } 1123 next_contiguous_offset = offset + s->cluster_size; 1124 } 1125 1126 /* Mark cluster as used */ 1127 inc_refcounts(bs, res, refcount_table,refcount_table_size, 1128 offset, s->cluster_size); 1129 1130 /* Correct offsets are cluster aligned */ 1131 if (offset_into_cluster(s, offset)) { 1132 fprintf(stderr, "ERROR offset=%" PRIx64 ": Cluster is not " 1133 "properly aligned; L2 entry corrupted.\n", offset); 1134 res->corruptions++; 1135 } 1136 break; 1137 } 1138 1139 case QCOW2_CLUSTER_UNALLOCATED: 1140 break; 1141 1142 default: 1143 abort(); 1144 } 1145 } 1146 1147 g_free(l2_table); 1148 return 0; 1149 1150 fail: 1151 fprintf(stderr, "ERROR: I/O error in check_refcounts_l2\n"); 1152 g_free(l2_table); 1153 return -EIO; 1154 } 1155 1156 /* 1157 * Increases the refcount for the L1 table, its L2 tables and all referenced 1158 * clusters in the given refcount table. While doing so, performs some checks 1159 * on L1 and L2 entries. 1160 * 1161 * Returns the number of errors found by the checks or -errno if an internal 1162 * error occurred. 1163 */ 1164 static int check_refcounts_l1(BlockDriverState *bs, 1165 BdrvCheckResult *res, 1166 uint16_t *refcount_table, 1167 int refcount_table_size, 1168 int64_t l1_table_offset, int l1_size, 1169 int flags) 1170 { 1171 BDRVQcowState *s = bs->opaque; 1172 uint64_t *l1_table, l2_offset, l1_size2; 1173 int i, ret; 1174 1175 l1_size2 = l1_size * sizeof(uint64_t); 1176 1177 /* Mark L1 table as used */ 1178 inc_refcounts(bs, res, refcount_table, refcount_table_size, 1179 l1_table_offset, l1_size2); 1180 1181 /* Read L1 table entries from disk */ 1182 if (l1_size2 == 0) { 1183 l1_table = NULL; 1184 } else { 1185 l1_table = g_malloc(l1_size2); 1186 if (bdrv_pread(bs->file, l1_table_offset, 1187 l1_table, l1_size2) != l1_size2) 1188 goto fail; 1189 for(i = 0;i < l1_size; i++) 1190 be64_to_cpus(&l1_table[i]); 1191 } 1192 1193 /* Do the actual checks */ 1194 for(i = 0; i < l1_size; i++) { 1195 l2_offset = l1_table[i]; 1196 if (l2_offset) { 1197 /* Mark L2 table as used */ 1198 l2_offset &= L1E_OFFSET_MASK; 1199 inc_refcounts(bs, res, refcount_table, refcount_table_size, 1200 l2_offset, s->cluster_size); 1201 1202 /* L2 tables are cluster aligned */ 1203 if (offset_into_cluster(s, l2_offset)) { 1204 fprintf(stderr, "ERROR l2_offset=%" PRIx64 ": Table is not " 1205 "cluster aligned; L1 entry corrupted\n", l2_offset); 1206 res->corruptions++; 1207 } 1208 1209 /* Process and check L2 entries */ 1210 ret = check_refcounts_l2(bs, res, refcount_table, 1211 refcount_table_size, l2_offset, flags); 1212 if (ret < 0) { 1213 goto fail; 1214 } 1215 } 1216 } 1217 g_free(l1_table); 1218 return 0; 1219 1220 fail: 1221 fprintf(stderr, "ERROR: I/O error in check_refcounts_l1\n"); 1222 res->check_errors++; 1223 g_free(l1_table); 1224 return -EIO; 1225 } 1226 1227 /* 1228 * Checks the OFLAG_COPIED flag for all L1 and L2 entries. 1229 * 1230 * This function does not print an error message nor does it increment 1231 * check_errors if get_refcount fails (this is because such an error will have 1232 * been already detected and sufficiently signaled by the calling function 1233 * (qcow2_check_refcounts) by the time this function is called). 1234 */ 1235 static int check_oflag_copied(BlockDriverState *bs, BdrvCheckResult *res, 1236 BdrvCheckMode fix) 1237 { 1238 BDRVQcowState *s = bs->opaque; 1239 uint64_t *l2_table = qemu_blockalign(bs, s->cluster_size); 1240 int ret; 1241 int refcount; 1242 int i, j; 1243 1244 for (i = 0; i < s->l1_size; i++) { 1245 uint64_t l1_entry = s->l1_table[i]; 1246 uint64_t l2_offset = l1_entry & L1E_OFFSET_MASK; 1247 bool l2_dirty = false; 1248 1249 if (!l2_offset) { 1250 continue; 1251 } 1252 1253 refcount = get_refcount(bs, l2_offset >> s->cluster_bits); 1254 if (refcount < 0) { 1255 /* don't print message nor increment check_errors */ 1256 continue; 1257 } 1258 if ((refcount == 1) != ((l1_entry & QCOW_OFLAG_COPIED) != 0)) { 1259 fprintf(stderr, "%s OFLAG_COPIED L2 cluster: l1_index=%d " 1260 "l1_entry=%" PRIx64 " refcount=%d\n", 1261 fix & BDRV_FIX_ERRORS ? "Repairing" : 1262 "ERROR", 1263 i, l1_entry, refcount); 1264 if (fix & BDRV_FIX_ERRORS) { 1265 s->l1_table[i] = refcount == 1 1266 ? l1_entry | QCOW_OFLAG_COPIED 1267 : l1_entry & ~QCOW_OFLAG_COPIED; 1268 ret = qcow2_write_l1_entry(bs, i); 1269 if (ret < 0) { 1270 res->check_errors++; 1271 goto fail; 1272 } 1273 res->corruptions_fixed++; 1274 } else { 1275 res->corruptions++; 1276 } 1277 } 1278 1279 ret = bdrv_pread(bs->file, l2_offset, l2_table, 1280 s->l2_size * sizeof(uint64_t)); 1281 if (ret < 0) { 1282 fprintf(stderr, "ERROR: Could not read L2 table: %s\n", 1283 strerror(-ret)); 1284 res->check_errors++; 1285 goto fail; 1286 } 1287 1288 for (j = 0; j < s->l2_size; j++) { 1289 uint64_t l2_entry = be64_to_cpu(l2_table[j]); 1290 uint64_t data_offset = l2_entry & L2E_OFFSET_MASK; 1291 int cluster_type = qcow2_get_cluster_type(l2_entry); 1292 1293 if ((cluster_type == QCOW2_CLUSTER_NORMAL) || 1294 ((cluster_type == QCOW2_CLUSTER_ZERO) && (data_offset != 0))) { 1295 refcount = get_refcount(bs, data_offset >> s->cluster_bits); 1296 if (refcount < 0) { 1297 /* don't print message nor increment check_errors */ 1298 continue; 1299 } 1300 if ((refcount == 1) != ((l2_entry & QCOW_OFLAG_COPIED) != 0)) { 1301 fprintf(stderr, "%s OFLAG_COPIED data cluster: " 1302 "l2_entry=%" PRIx64 " refcount=%d\n", 1303 fix & BDRV_FIX_ERRORS ? "Repairing" : 1304 "ERROR", 1305 l2_entry, refcount); 1306 if (fix & BDRV_FIX_ERRORS) { 1307 l2_table[j] = cpu_to_be64(refcount == 1 1308 ? l2_entry | QCOW_OFLAG_COPIED 1309 : l2_entry & ~QCOW_OFLAG_COPIED); 1310 l2_dirty = true; 1311 res->corruptions_fixed++; 1312 } else { 1313 res->corruptions++; 1314 } 1315 } 1316 } 1317 } 1318 1319 if (l2_dirty) { 1320 ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_ACTIVE_L2, 1321 l2_offset, s->cluster_size); 1322 if (ret < 0) { 1323 fprintf(stderr, "ERROR: Could not write L2 table; metadata " 1324 "overlap check failed: %s\n", strerror(-ret)); 1325 res->check_errors++; 1326 goto fail; 1327 } 1328 1329 ret = bdrv_pwrite(bs->file, l2_offset, l2_table, s->cluster_size); 1330 if (ret < 0) { 1331 fprintf(stderr, "ERROR: Could not write L2 table: %s\n", 1332 strerror(-ret)); 1333 res->check_errors++; 1334 goto fail; 1335 } 1336 } 1337 } 1338 1339 ret = 0; 1340 1341 fail: 1342 qemu_vfree(l2_table); 1343 return ret; 1344 } 1345 1346 /* 1347 * Writes one sector of the refcount table to the disk 1348 */ 1349 #define RT_ENTRIES_PER_SECTOR (512 / sizeof(uint64_t)) 1350 static int write_reftable_entry(BlockDriverState *bs, int rt_index) 1351 { 1352 BDRVQcowState *s = bs->opaque; 1353 uint64_t buf[RT_ENTRIES_PER_SECTOR]; 1354 int rt_start_index; 1355 int i, ret; 1356 1357 rt_start_index = rt_index & ~(RT_ENTRIES_PER_SECTOR - 1); 1358 for (i = 0; i < RT_ENTRIES_PER_SECTOR; i++) { 1359 buf[i] = cpu_to_be64(s->refcount_table[rt_start_index + i]); 1360 } 1361 1362 ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_REFCOUNT_TABLE, 1363 s->refcount_table_offset + rt_start_index * sizeof(uint64_t), 1364 sizeof(buf)); 1365 if (ret < 0) { 1366 return ret; 1367 } 1368 1369 BLKDBG_EVENT(bs->file, BLKDBG_REFTABLE_UPDATE); 1370 ret = bdrv_pwrite_sync(bs->file, s->refcount_table_offset + 1371 rt_start_index * sizeof(uint64_t), buf, sizeof(buf)); 1372 if (ret < 0) { 1373 return ret; 1374 } 1375 1376 return 0; 1377 } 1378 1379 /* 1380 * Allocates a new cluster for the given refcount block (represented by its 1381 * offset in the image file) and copies the current content there. This function 1382 * does _not_ decrement the reference count for the currently occupied cluster. 1383 * 1384 * This function prints an informative message to stderr on error (and returns 1385 * -errno); on success, 0 is returned. 1386 */ 1387 static int64_t realloc_refcount_block(BlockDriverState *bs, int reftable_index, 1388 uint64_t offset) 1389 { 1390 BDRVQcowState *s = bs->opaque; 1391 int64_t new_offset = 0; 1392 void *refcount_block = NULL; 1393 int ret; 1394 1395 /* allocate new refcount block */ 1396 new_offset = qcow2_alloc_clusters(bs, s->cluster_size); 1397 if (new_offset < 0) { 1398 fprintf(stderr, "Could not allocate new cluster: %s\n", 1399 strerror(-new_offset)); 1400 ret = new_offset; 1401 goto fail; 1402 } 1403 1404 /* fetch current refcount block content */ 1405 ret = qcow2_cache_get(bs, s->refcount_block_cache, offset, &refcount_block); 1406 if (ret < 0) { 1407 fprintf(stderr, "Could not fetch refcount block: %s\n", strerror(-ret)); 1408 goto fail; 1409 } 1410 1411 /* new block has not yet been entered into refcount table, therefore it is 1412 * no refcount block yet (regarding this check) */ 1413 ret = qcow2_pre_write_overlap_check(bs, 0, new_offset, s->cluster_size); 1414 if (ret < 0) { 1415 fprintf(stderr, "Could not write refcount block; metadata overlap " 1416 "check failed: %s\n", strerror(-ret)); 1417 /* the image will be marked corrupt, so don't even attempt on freeing 1418 * the cluster */ 1419 new_offset = 0; 1420 goto fail; 1421 } 1422 1423 /* write to new block */ 1424 ret = bdrv_write(bs->file, new_offset / BDRV_SECTOR_SIZE, refcount_block, 1425 s->cluster_sectors); 1426 if (ret < 0) { 1427 fprintf(stderr, "Could not write refcount block: %s\n", strerror(-ret)); 1428 goto fail; 1429 } 1430 1431 /* update refcount table */ 1432 assert(!offset_into_cluster(s, new_offset)); 1433 s->refcount_table[reftable_index] = new_offset; 1434 ret = write_reftable_entry(bs, reftable_index); 1435 if (ret < 0) { 1436 fprintf(stderr, "Could not update refcount table: %s\n", 1437 strerror(-ret)); 1438 goto fail; 1439 } 1440 1441 fail: 1442 if (new_offset && (ret < 0)) { 1443 qcow2_free_clusters(bs, new_offset, s->cluster_size, 1444 QCOW2_DISCARD_ALWAYS); 1445 } 1446 if (refcount_block) { 1447 if (ret < 0) { 1448 qcow2_cache_put(bs, s->refcount_block_cache, &refcount_block); 1449 } else { 1450 ret = qcow2_cache_put(bs, s->refcount_block_cache, &refcount_block); 1451 } 1452 } 1453 if (ret < 0) { 1454 return ret; 1455 } 1456 return new_offset; 1457 } 1458 1459 /* 1460 * Checks an image for refcount consistency. 1461 * 1462 * Returns 0 if no errors are found, the number of errors in case the image is 1463 * detected as corrupted, and -errno when an internal error occurred. 1464 */ 1465 int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res, 1466 BdrvCheckMode fix) 1467 { 1468 BDRVQcowState *s = bs->opaque; 1469 int64_t size, i, highest_cluster; 1470 int nb_clusters, refcount1, refcount2; 1471 QCowSnapshot *sn; 1472 uint16_t *refcount_table; 1473 int ret; 1474 1475 size = bdrv_getlength(bs->file); 1476 nb_clusters = size_to_clusters(s, size); 1477 refcount_table = g_malloc0(nb_clusters * sizeof(uint16_t)); 1478 1479 res->bfi.total_clusters = 1480 size_to_clusters(s, bs->total_sectors * BDRV_SECTOR_SIZE); 1481 1482 /* header */ 1483 inc_refcounts(bs, res, refcount_table, nb_clusters, 1484 0, s->cluster_size); 1485 1486 /* current L1 table */ 1487 ret = check_refcounts_l1(bs, res, refcount_table, nb_clusters, 1488 s->l1_table_offset, s->l1_size, CHECK_FRAG_INFO); 1489 if (ret < 0) { 1490 goto fail; 1491 } 1492 1493 /* snapshots */ 1494 for(i = 0; i < s->nb_snapshots; i++) { 1495 sn = s->snapshots + i; 1496 ret = check_refcounts_l1(bs, res, refcount_table, nb_clusters, 1497 sn->l1_table_offset, sn->l1_size, 0); 1498 if (ret < 0) { 1499 goto fail; 1500 } 1501 } 1502 inc_refcounts(bs, res, refcount_table, nb_clusters, 1503 s->snapshots_offset, s->snapshots_size); 1504 1505 /* refcount data */ 1506 inc_refcounts(bs, res, refcount_table, nb_clusters, 1507 s->refcount_table_offset, 1508 s->refcount_table_size * sizeof(uint64_t)); 1509 1510 for(i = 0; i < s->refcount_table_size; i++) { 1511 uint64_t offset, cluster; 1512 offset = s->refcount_table[i]; 1513 cluster = offset >> s->cluster_bits; 1514 1515 /* Refcount blocks are cluster aligned */ 1516 if (offset_into_cluster(s, offset)) { 1517 fprintf(stderr, "ERROR refcount block %" PRId64 " is not " 1518 "cluster aligned; refcount table entry corrupted\n", i); 1519 res->corruptions++; 1520 continue; 1521 } 1522 1523 if (cluster >= nb_clusters) { 1524 fprintf(stderr, "ERROR refcount block %" PRId64 1525 " is outside image\n", i); 1526 res->corruptions++; 1527 continue; 1528 } 1529 1530 if (offset != 0) { 1531 inc_refcounts(bs, res, refcount_table, nb_clusters, 1532 offset, s->cluster_size); 1533 if (refcount_table[cluster] != 1) { 1534 fprintf(stderr, "%s refcount block %" PRId64 1535 " refcount=%d\n", 1536 fix & BDRV_FIX_ERRORS ? "Repairing" : 1537 "ERROR", 1538 i, refcount_table[cluster]); 1539 1540 if (fix & BDRV_FIX_ERRORS) { 1541 int64_t new_offset; 1542 1543 new_offset = realloc_refcount_block(bs, i, offset); 1544 if (new_offset < 0) { 1545 res->corruptions++; 1546 continue; 1547 } 1548 1549 /* update refcounts */ 1550 if ((new_offset >> s->cluster_bits) >= nb_clusters) { 1551 /* increase refcount_table size if necessary */ 1552 int old_nb_clusters = nb_clusters; 1553 nb_clusters = (new_offset >> s->cluster_bits) + 1; 1554 refcount_table = g_realloc(refcount_table, 1555 nb_clusters * sizeof(uint16_t)); 1556 memset(&refcount_table[old_nb_clusters], 0, (nb_clusters 1557 - old_nb_clusters) * sizeof(uint16_t)); 1558 } 1559 refcount_table[cluster]--; 1560 inc_refcounts(bs, res, refcount_table, nb_clusters, 1561 new_offset, s->cluster_size); 1562 1563 res->corruptions_fixed++; 1564 } else { 1565 res->corruptions++; 1566 } 1567 } 1568 } 1569 } 1570 1571 /* compare ref counts */ 1572 for (i = 0, highest_cluster = 0; i < nb_clusters; i++) { 1573 refcount1 = get_refcount(bs, i); 1574 if (refcount1 < 0) { 1575 fprintf(stderr, "Can't get refcount for cluster %" PRId64 ": %s\n", 1576 i, strerror(-refcount1)); 1577 res->check_errors++; 1578 continue; 1579 } 1580 1581 refcount2 = refcount_table[i]; 1582 1583 if (refcount1 > 0 || refcount2 > 0) { 1584 highest_cluster = i; 1585 } 1586 1587 if (refcount1 != refcount2) { 1588 1589 /* Check if we're allowed to fix the mismatch */ 1590 int *num_fixed = NULL; 1591 if (refcount1 > refcount2 && (fix & BDRV_FIX_LEAKS)) { 1592 num_fixed = &res->leaks_fixed; 1593 } else if (refcount1 < refcount2 && (fix & BDRV_FIX_ERRORS)) { 1594 num_fixed = &res->corruptions_fixed; 1595 } 1596 1597 fprintf(stderr, "%s cluster %" PRId64 " refcount=%d reference=%d\n", 1598 num_fixed != NULL ? "Repairing" : 1599 refcount1 < refcount2 ? "ERROR" : 1600 "Leaked", 1601 i, refcount1, refcount2); 1602 1603 if (num_fixed) { 1604 ret = update_refcount(bs, i << s->cluster_bits, 1, 1605 refcount2 - refcount1, 1606 QCOW2_DISCARD_ALWAYS); 1607 if (ret >= 0) { 1608 (*num_fixed)++; 1609 continue; 1610 } 1611 } 1612 1613 /* And if we couldn't, print an error */ 1614 if (refcount1 < refcount2) { 1615 res->corruptions++; 1616 } else { 1617 res->leaks++; 1618 } 1619 } 1620 } 1621 1622 /* check OFLAG_COPIED */ 1623 ret = check_oflag_copied(bs, res, fix); 1624 if (ret < 0) { 1625 goto fail; 1626 } 1627 1628 res->image_end_offset = (highest_cluster + 1) * s->cluster_size; 1629 ret = 0; 1630 1631 fail: 1632 g_free(refcount_table); 1633 1634 return ret; 1635 } 1636 1637 #define overlaps_with(ofs, sz) \ 1638 ranges_overlap(offset, size, ofs, sz) 1639 1640 /* 1641 * Checks if the given offset into the image file is actually free to use by 1642 * looking for overlaps with important metadata sections (L1/L2 tables etc.), 1643 * i.e. a sanity check without relying on the refcount tables. 1644 * 1645 * The ign parameter specifies what checks not to perform (being a bitmask of 1646 * QCow2MetadataOverlap values), i.e., what sections to ignore. 1647 * 1648 * Returns: 1649 * - 0 if writing to this offset will not affect the mentioned metadata 1650 * - a positive QCow2MetadataOverlap value indicating one overlapping section 1651 * - a negative value (-errno) indicating an error while performing a check, 1652 * e.g. when bdrv_read failed on QCOW2_OL_INACTIVE_L2 1653 */ 1654 int qcow2_check_metadata_overlap(BlockDriverState *bs, int ign, int64_t offset, 1655 int64_t size) 1656 { 1657 BDRVQcowState *s = bs->opaque; 1658 int chk = s->overlap_check & ~ign; 1659 int i, j; 1660 1661 if (!size) { 1662 return 0; 1663 } 1664 1665 if (chk & QCOW2_OL_MAIN_HEADER) { 1666 if (offset < s->cluster_size) { 1667 return QCOW2_OL_MAIN_HEADER; 1668 } 1669 } 1670 1671 /* align range to test to cluster boundaries */ 1672 size = align_offset(offset_into_cluster(s, offset) + size, s->cluster_size); 1673 offset = start_of_cluster(s, offset); 1674 1675 if ((chk & QCOW2_OL_ACTIVE_L1) && s->l1_size) { 1676 if (overlaps_with(s->l1_table_offset, s->l1_size * sizeof(uint64_t))) { 1677 return QCOW2_OL_ACTIVE_L1; 1678 } 1679 } 1680 1681 if ((chk & QCOW2_OL_REFCOUNT_TABLE) && s->refcount_table_size) { 1682 if (overlaps_with(s->refcount_table_offset, 1683 s->refcount_table_size * sizeof(uint64_t))) { 1684 return QCOW2_OL_REFCOUNT_TABLE; 1685 } 1686 } 1687 1688 if ((chk & QCOW2_OL_SNAPSHOT_TABLE) && s->snapshots_size) { 1689 if (overlaps_with(s->snapshots_offset, s->snapshots_size)) { 1690 return QCOW2_OL_SNAPSHOT_TABLE; 1691 } 1692 } 1693 1694 if ((chk & QCOW2_OL_INACTIVE_L1) && s->snapshots) { 1695 for (i = 0; i < s->nb_snapshots; i++) { 1696 if (s->snapshots[i].l1_size && 1697 overlaps_with(s->snapshots[i].l1_table_offset, 1698 s->snapshots[i].l1_size * sizeof(uint64_t))) { 1699 return QCOW2_OL_INACTIVE_L1; 1700 } 1701 } 1702 } 1703 1704 if ((chk & QCOW2_OL_ACTIVE_L2) && s->l1_table) { 1705 for (i = 0; i < s->l1_size; i++) { 1706 if ((s->l1_table[i] & L1E_OFFSET_MASK) && 1707 overlaps_with(s->l1_table[i] & L1E_OFFSET_MASK, 1708 s->cluster_size)) { 1709 return QCOW2_OL_ACTIVE_L2; 1710 } 1711 } 1712 } 1713 1714 if ((chk & QCOW2_OL_REFCOUNT_BLOCK) && s->refcount_table) { 1715 for (i = 0; i < s->refcount_table_size; i++) { 1716 if ((s->refcount_table[i] & REFT_OFFSET_MASK) && 1717 overlaps_with(s->refcount_table[i] & REFT_OFFSET_MASK, 1718 s->cluster_size)) { 1719 return QCOW2_OL_REFCOUNT_BLOCK; 1720 } 1721 } 1722 } 1723 1724 if ((chk & QCOW2_OL_INACTIVE_L2) && s->snapshots) { 1725 for (i = 0; i < s->nb_snapshots; i++) { 1726 uint64_t l1_ofs = s->snapshots[i].l1_table_offset; 1727 uint32_t l1_sz = s->snapshots[i].l1_size; 1728 uint64_t l1_sz2 = l1_sz * sizeof(uint64_t); 1729 uint64_t *l1 = g_malloc(l1_sz2); 1730 int ret; 1731 1732 ret = bdrv_pread(bs->file, l1_ofs, l1, l1_sz2); 1733 if (ret < 0) { 1734 g_free(l1); 1735 return ret; 1736 } 1737 1738 for (j = 0; j < l1_sz; j++) { 1739 uint64_t l2_ofs = be64_to_cpu(l1[j]) & L1E_OFFSET_MASK; 1740 if (l2_ofs && overlaps_with(l2_ofs, s->cluster_size)) { 1741 g_free(l1); 1742 return QCOW2_OL_INACTIVE_L2; 1743 } 1744 } 1745 1746 g_free(l1); 1747 } 1748 } 1749 1750 return 0; 1751 } 1752 1753 static const char *metadata_ol_names[] = { 1754 [QCOW2_OL_MAIN_HEADER_BITNR] = "qcow2_header", 1755 [QCOW2_OL_ACTIVE_L1_BITNR] = "active L1 table", 1756 [QCOW2_OL_ACTIVE_L2_BITNR] = "active L2 table", 1757 [QCOW2_OL_REFCOUNT_TABLE_BITNR] = "refcount table", 1758 [QCOW2_OL_REFCOUNT_BLOCK_BITNR] = "refcount block", 1759 [QCOW2_OL_SNAPSHOT_TABLE_BITNR] = "snapshot table", 1760 [QCOW2_OL_INACTIVE_L1_BITNR] = "inactive L1 table", 1761 [QCOW2_OL_INACTIVE_L2_BITNR] = "inactive L2 table", 1762 }; 1763 1764 /* 1765 * First performs a check for metadata overlaps (through 1766 * qcow2_check_metadata_overlap); if that fails with a negative value (error 1767 * while performing a check), that value is returned. If an impending overlap 1768 * is detected, the BDS will be made unusable, the qcow2 file marked corrupt 1769 * and -EIO returned. 1770 * 1771 * Returns 0 if there were neither overlaps nor errors while checking for 1772 * overlaps; or a negative value (-errno) on error. 1773 */ 1774 int qcow2_pre_write_overlap_check(BlockDriverState *bs, int ign, int64_t offset, 1775 int64_t size) 1776 { 1777 int ret = qcow2_check_metadata_overlap(bs, ign, offset, size); 1778 1779 if (ret < 0) { 1780 return ret; 1781 } else if (ret > 0) { 1782 int metadata_ol_bitnr = ffs(ret) - 1; 1783 char *message; 1784 QObject *data; 1785 1786 assert(metadata_ol_bitnr < QCOW2_OL_MAX_BITNR); 1787 1788 fprintf(stderr, "qcow2: Preventing invalid write on metadata (overlaps " 1789 "with %s); image marked as corrupt.\n", 1790 metadata_ol_names[metadata_ol_bitnr]); 1791 message = g_strdup_printf("Prevented %s overwrite", 1792 metadata_ol_names[metadata_ol_bitnr]); 1793 data = qobject_from_jsonf("{ 'device': %s, 'msg': %s, 'offset': %" 1794 PRId64 ", 'size': %" PRId64 " }", bs->device_name, message, 1795 offset, size); 1796 monitor_protocol_event(QEVENT_BLOCK_IMAGE_CORRUPTED, data); 1797 g_free(message); 1798 qobject_decref(data); 1799 1800 qcow2_mark_corrupt(bs); 1801 bs->drv = NULL; /* make BDS unusable */ 1802 return -EIO; 1803 } 1804 1805 return 0; 1806 } 1807