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 30 static int64_t alloc_clusters_noref(BlockDriverState *bs, uint64_t size); 31 static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs, 32 int64_t offset, int64_t length, uint64_t addend, 33 bool decrease, enum qcow2_discard_type type); 34 35 static uint64_t get_refcount_ro0(const void *refcount_array, uint64_t index); 36 static uint64_t get_refcount_ro1(const void *refcount_array, uint64_t index); 37 static uint64_t get_refcount_ro2(const void *refcount_array, uint64_t index); 38 static uint64_t get_refcount_ro3(const void *refcount_array, uint64_t index); 39 static uint64_t get_refcount_ro4(const void *refcount_array, uint64_t index); 40 static uint64_t get_refcount_ro5(const void *refcount_array, uint64_t index); 41 static uint64_t get_refcount_ro6(const void *refcount_array, uint64_t index); 42 43 static void set_refcount_ro0(void *refcount_array, uint64_t index, 44 uint64_t value); 45 static void set_refcount_ro1(void *refcount_array, uint64_t index, 46 uint64_t value); 47 static void set_refcount_ro2(void *refcount_array, uint64_t index, 48 uint64_t value); 49 static void set_refcount_ro3(void *refcount_array, uint64_t index, 50 uint64_t value); 51 static void set_refcount_ro4(void *refcount_array, uint64_t index, 52 uint64_t value); 53 static void set_refcount_ro5(void *refcount_array, uint64_t index, 54 uint64_t value); 55 static void set_refcount_ro6(void *refcount_array, uint64_t index, 56 uint64_t value); 57 58 59 static Qcow2GetRefcountFunc *const get_refcount_funcs[] = { 60 &get_refcount_ro0, 61 &get_refcount_ro1, 62 &get_refcount_ro2, 63 &get_refcount_ro3, 64 &get_refcount_ro4, 65 &get_refcount_ro5, 66 &get_refcount_ro6 67 }; 68 69 static Qcow2SetRefcountFunc *const set_refcount_funcs[] = { 70 &set_refcount_ro0, 71 &set_refcount_ro1, 72 &set_refcount_ro2, 73 &set_refcount_ro3, 74 &set_refcount_ro4, 75 &set_refcount_ro5, 76 &set_refcount_ro6 77 }; 78 79 80 /*********************************************************/ 81 /* refcount handling */ 82 83 int qcow2_refcount_init(BlockDriverState *bs) 84 { 85 BDRVQcowState *s = bs->opaque; 86 unsigned int refcount_table_size2, i; 87 int ret; 88 89 assert(s->refcount_order >= 0 && s->refcount_order <= 6); 90 91 s->get_refcount = get_refcount_funcs[s->refcount_order]; 92 s->set_refcount = set_refcount_funcs[s->refcount_order]; 93 94 assert(s->refcount_table_size <= INT_MAX / sizeof(uint64_t)); 95 refcount_table_size2 = s->refcount_table_size * sizeof(uint64_t); 96 s->refcount_table = g_try_malloc(refcount_table_size2); 97 98 if (s->refcount_table_size > 0) { 99 if (s->refcount_table == NULL) { 100 ret = -ENOMEM; 101 goto fail; 102 } 103 BLKDBG_EVENT(bs->file, BLKDBG_REFTABLE_LOAD); 104 ret = bdrv_pread(bs->file, s->refcount_table_offset, 105 s->refcount_table, refcount_table_size2); 106 if (ret < 0) { 107 goto fail; 108 } 109 for(i = 0; i < s->refcount_table_size; i++) 110 be64_to_cpus(&s->refcount_table[i]); 111 } 112 return 0; 113 fail: 114 return ret; 115 } 116 117 void qcow2_refcount_close(BlockDriverState *bs) 118 { 119 BDRVQcowState *s = bs->opaque; 120 g_free(s->refcount_table); 121 } 122 123 124 static uint64_t get_refcount_ro0(const void *refcount_array, uint64_t index) 125 { 126 return (((const uint8_t *)refcount_array)[index / 8] >> (index % 8)) & 0x1; 127 } 128 129 static void set_refcount_ro0(void *refcount_array, uint64_t index, 130 uint64_t value) 131 { 132 assert(!(value >> 1)); 133 ((uint8_t *)refcount_array)[index / 8] &= ~(0x1 << (index % 8)); 134 ((uint8_t *)refcount_array)[index / 8] |= value << (index % 8); 135 } 136 137 static uint64_t get_refcount_ro1(const void *refcount_array, uint64_t index) 138 { 139 return (((const uint8_t *)refcount_array)[index / 4] >> (2 * (index % 4))) 140 & 0x3; 141 } 142 143 static void set_refcount_ro1(void *refcount_array, uint64_t index, 144 uint64_t value) 145 { 146 assert(!(value >> 2)); 147 ((uint8_t *)refcount_array)[index / 4] &= ~(0x3 << (2 * (index % 4))); 148 ((uint8_t *)refcount_array)[index / 4] |= value << (2 * (index % 4)); 149 } 150 151 static uint64_t get_refcount_ro2(const void *refcount_array, uint64_t index) 152 { 153 return (((const uint8_t *)refcount_array)[index / 2] >> (4 * (index % 2))) 154 & 0xf; 155 } 156 157 static void set_refcount_ro2(void *refcount_array, uint64_t index, 158 uint64_t value) 159 { 160 assert(!(value >> 4)); 161 ((uint8_t *)refcount_array)[index / 2] &= ~(0xf << (4 * (index % 2))); 162 ((uint8_t *)refcount_array)[index / 2] |= value << (4 * (index % 2)); 163 } 164 165 static uint64_t get_refcount_ro3(const void *refcount_array, uint64_t index) 166 { 167 return ((const uint8_t *)refcount_array)[index]; 168 } 169 170 static void set_refcount_ro3(void *refcount_array, uint64_t index, 171 uint64_t value) 172 { 173 assert(!(value >> 8)); 174 ((uint8_t *)refcount_array)[index] = value; 175 } 176 177 static uint64_t get_refcount_ro4(const void *refcount_array, uint64_t index) 178 { 179 return be16_to_cpu(((const uint16_t *)refcount_array)[index]); 180 } 181 182 static void set_refcount_ro4(void *refcount_array, uint64_t index, 183 uint64_t value) 184 { 185 assert(!(value >> 16)); 186 ((uint16_t *)refcount_array)[index] = cpu_to_be16(value); 187 } 188 189 static uint64_t get_refcount_ro5(const void *refcount_array, uint64_t index) 190 { 191 return be32_to_cpu(((const uint32_t *)refcount_array)[index]); 192 } 193 194 static void set_refcount_ro5(void *refcount_array, uint64_t index, 195 uint64_t value) 196 { 197 assert(!(value >> 32)); 198 ((uint32_t *)refcount_array)[index] = cpu_to_be32(value); 199 } 200 201 static uint64_t get_refcount_ro6(const void *refcount_array, uint64_t index) 202 { 203 return be64_to_cpu(((const uint64_t *)refcount_array)[index]); 204 } 205 206 static void set_refcount_ro6(void *refcount_array, uint64_t index, 207 uint64_t value) 208 { 209 ((uint64_t *)refcount_array)[index] = cpu_to_be64(value); 210 } 211 212 213 static int load_refcount_block(BlockDriverState *bs, 214 int64_t refcount_block_offset, 215 void **refcount_block) 216 { 217 BDRVQcowState *s = bs->opaque; 218 int ret; 219 220 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_LOAD); 221 ret = qcow2_cache_get(bs, s->refcount_block_cache, refcount_block_offset, 222 refcount_block); 223 224 return ret; 225 } 226 227 /* 228 * Retrieves the refcount of the cluster given by its index and stores it in 229 * *refcount. Returns 0 on success and -errno on failure. 230 */ 231 int qcow2_get_refcount(BlockDriverState *bs, int64_t cluster_index, 232 uint64_t *refcount) 233 { 234 BDRVQcowState *s = bs->opaque; 235 uint64_t refcount_table_index, block_index; 236 int64_t refcount_block_offset; 237 int ret; 238 void *refcount_block; 239 240 refcount_table_index = cluster_index >> s->refcount_block_bits; 241 if (refcount_table_index >= s->refcount_table_size) { 242 *refcount = 0; 243 return 0; 244 } 245 refcount_block_offset = 246 s->refcount_table[refcount_table_index] & REFT_OFFSET_MASK; 247 if (!refcount_block_offset) { 248 *refcount = 0; 249 return 0; 250 } 251 252 if (offset_into_cluster(s, refcount_block_offset)) { 253 qcow2_signal_corruption(bs, true, -1, -1, "Refblock offset %#" PRIx64 254 " unaligned (reftable index: %#" PRIx64 ")", 255 refcount_block_offset, refcount_table_index); 256 return -EIO; 257 } 258 259 ret = qcow2_cache_get(bs, s->refcount_block_cache, refcount_block_offset, 260 &refcount_block); 261 if (ret < 0) { 262 return ret; 263 } 264 265 block_index = cluster_index & (s->refcount_block_size - 1); 266 *refcount = s->get_refcount(refcount_block, block_index); 267 268 qcow2_cache_put(bs, s->refcount_block_cache, &refcount_block); 269 270 return 0; 271 } 272 273 /* 274 * Rounds the refcount table size up to avoid growing the table for each single 275 * refcount block that is allocated. 276 */ 277 static unsigned int next_refcount_table_size(BDRVQcowState *s, 278 unsigned int min_size) 279 { 280 unsigned int min_clusters = (min_size >> (s->cluster_bits - 3)) + 1; 281 unsigned int refcount_table_clusters = 282 MAX(1, s->refcount_table_size >> (s->cluster_bits - 3)); 283 284 while (min_clusters > refcount_table_clusters) { 285 refcount_table_clusters = (refcount_table_clusters * 3 + 1) / 2; 286 } 287 288 return refcount_table_clusters << (s->cluster_bits - 3); 289 } 290 291 292 /* Checks if two offsets are described by the same refcount block */ 293 static int in_same_refcount_block(BDRVQcowState *s, uint64_t offset_a, 294 uint64_t offset_b) 295 { 296 uint64_t block_a = offset_a >> (s->cluster_bits + s->refcount_block_bits); 297 uint64_t block_b = offset_b >> (s->cluster_bits + s->refcount_block_bits); 298 299 return (block_a == block_b); 300 } 301 302 /* 303 * Loads a refcount block. If it doesn't exist yet, it is allocated first 304 * (including growing the refcount table if needed). 305 * 306 * Returns 0 on success or -errno in error case 307 */ 308 static int alloc_refcount_block(BlockDriverState *bs, 309 int64_t cluster_index, void **refcount_block) 310 { 311 BDRVQcowState *s = bs->opaque; 312 unsigned int refcount_table_index; 313 int ret; 314 315 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC); 316 317 /* Find the refcount block for the given cluster */ 318 refcount_table_index = cluster_index >> s->refcount_block_bits; 319 320 if (refcount_table_index < s->refcount_table_size) { 321 322 uint64_t refcount_block_offset = 323 s->refcount_table[refcount_table_index] & REFT_OFFSET_MASK; 324 325 /* If it's already there, we're done */ 326 if (refcount_block_offset) { 327 if (offset_into_cluster(s, refcount_block_offset)) { 328 qcow2_signal_corruption(bs, true, -1, -1, "Refblock offset %#" 329 PRIx64 " unaligned (reftable index: " 330 "%#x)", refcount_block_offset, 331 refcount_table_index); 332 return -EIO; 333 } 334 335 return load_refcount_block(bs, refcount_block_offset, 336 refcount_block); 337 } 338 } 339 340 /* 341 * If we came here, we need to allocate something. Something is at least 342 * a cluster for the new refcount block. It may also include a new refcount 343 * table if the old refcount table is too small. 344 * 345 * Note that allocating clusters here needs some special care: 346 * 347 * - We can't use the normal qcow2_alloc_clusters(), it would try to 348 * increase the refcount and very likely we would end up with an endless 349 * recursion. Instead we must place the refcount blocks in a way that 350 * they can describe them themselves. 351 * 352 * - We need to consider that at this point we are inside update_refcounts 353 * and potentially doing an initial refcount increase. This means that 354 * some clusters have already been allocated by the caller, but their 355 * refcount isn't accurate yet. If we allocate clusters for metadata, we 356 * need to return -EAGAIN to signal the caller that it needs to restart 357 * the search for free clusters. 358 * 359 * - alloc_clusters_noref and qcow2_free_clusters may load a different 360 * refcount block into the cache 361 */ 362 363 *refcount_block = NULL; 364 365 /* We write to the refcount table, so we might depend on L2 tables */ 366 ret = qcow2_cache_flush(bs, s->l2_table_cache); 367 if (ret < 0) { 368 return ret; 369 } 370 371 /* Allocate the refcount block itself and mark it as used */ 372 int64_t new_block = alloc_clusters_noref(bs, s->cluster_size); 373 if (new_block < 0) { 374 return new_block; 375 } 376 377 #ifdef DEBUG_ALLOC2 378 fprintf(stderr, "qcow2: Allocate refcount block %d for %" PRIx64 379 " at %" PRIx64 "\n", 380 refcount_table_index, cluster_index << s->cluster_bits, new_block); 381 #endif 382 383 if (in_same_refcount_block(s, new_block, cluster_index << s->cluster_bits)) { 384 /* Zero the new refcount block before updating it */ 385 ret = qcow2_cache_get_empty(bs, s->refcount_block_cache, new_block, 386 refcount_block); 387 if (ret < 0) { 388 goto fail_block; 389 } 390 391 memset(*refcount_block, 0, s->cluster_size); 392 393 /* The block describes itself, need to update the cache */ 394 int block_index = (new_block >> s->cluster_bits) & 395 (s->refcount_block_size - 1); 396 s->set_refcount(*refcount_block, block_index, 1); 397 } else { 398 /* Described somewhere else. This can recurse at most twice before we 399 * arrive at a block that describes itself. */ 400 ret = update_refcount(bs, new_block, s->cluster_size, 1, false, 401 QCOW2_DISCARD_NEVER); 402 if (ret < 0) { 403 goto fail_block; 404 } 405 406 ret = qcow2_cache_flush(bs, s->refcount_block_cache); 407 if (ret < 0) { 408 goto fail_block; 409 } 410 411 /* Initialize the new refcount block only after updating its refcount, 412 * update_refcount uses the refcount cache itself */ 413 ret = qcow2_cache_get_empty(bs, s->refcount_block_cache, new_block, 414 refcount_block); 415 if (ret < 0) { 416 goto fail_block; 417 } 418 419 memset(*refcount_block, 0, s->cluster_size); 420 } 421 422 /* Now the new refcount block needs to be written to disk */ 423 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_WRITE); 424 qcow2_cache_entry_mark_dirty(bs, s->refcount_block_cache, *refcount_block); 425 ret = qcow2_cache_flush(bs, s->refcount_block_cache); 426 if (ret < 0) { 427 goto fail_block; 428 } 429 430 /* If the refcount table is big enough, just hook the block up there */ 431 if (refcount_table_index < s->refcount_table_size) { 432 uint64_t data64 = cpu_to_be64(new_block); 433 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_HOOKUP); 434 ret = bdrv_pwrite_sync(bs->file, 435 s->refcount_table_offset + refcount_table_index * sizeof(uint64_t), 436 &data64, sizeof(data64)); 437 if (ret < 0) { 438 goto fail_block; 439 } 440 441 s->refcount_table[refcount_table_index] = new_block; 442 443 /* The new refcount block may be where the caller intended to put its 444 * data, so let it restart the search. */ 445 return -EAGAIN; 446 } 447 448 qcow2_cache_put(bs, s->refcount_block_cache, refcount_block); 449 450 /* 451 * If we come here, we need to grow the refcount table. Again, a new 452 * refcount table needs some space and we can't simply allocate to avoid 453 * endless recursion. 454 * 455 * Therefore let's grab new refcount blocks at the end of the image, which 456 * will describe themselves and the new refcount table. This way we can 457 * reference them only in the new table and do the switch to the new 458 * refcount table at once without producing an inconsistent state in 459 * between. 460 */ 461 BLKDBG_EVENT(bs->file, BLKDBG_REFTABLE_GROW); 462 463 /* Calculate the number of refcount blocks needed so far; this will be the 464 * basis for calculating the index of the first cluster used for the 465 * self-describing refcount structures which we are about to create. 466 * 467 * Because we reached this point, there cannot be any refcount entries for 468 * cluster_index or higher indices yet. However, because new_block has been 469 * allocated to describe that cluster (and it will assume this role later 470 * on), we cannot use that index; also, new_block may actually have a higher 471 * cluster index than cluster_index, so it needs to be taken into account 472 * here (and 1 needs to be added to its value because that cluster is used). 473 */ 474 uint64_t blocks_used = DIV_ROUND_UP(MAX(cluster_index + 1, 475 (new_block >> s->cluster_bits) + 1), 476 s->refcount_block_size); 477 478 if (blocks_used > QCOW_MAX_REFTABLE_SIZE / sizeof(uint64_t)) { 479 return -EFBIG; 480 } 481 482 /* And now we need at least one block more for the new metadata */ 483 uint64_t table_size = next_refcount_table_size(s, blocks_used + 1); 484 uint64_t last_table_size; 485 uint64_t blocks_clusters; 486 do { 487 uint64_t table_clusters = 488 size_to_clusters(s, table_size * sizeof(uint64_t)); 489 blocks_clusters = 1 + 490 ((table_clusters + s->refcount_block_size - 1) 491 / s->refcount_block_size); 492 uint64_t meta_clusters = table_clusters + blocks_clusters; 493 494 last_table_size = table_size; 495 table_size = next_refcount_table_size(s, blocks_used + 496 ((meta_clusters + s->refcount_block_size - 1) 497 / s->refcount_block_size)); 498 499 } while (last_table_size != table_size); 500 501 #ifdef DEBUG_ALLOC2 502 fprintf(stderr, "qcow2: Grow refcount table %" PRId32 " => %" PRId64 "\n", 503 s->refcount_table_size, table_size); 504 #endif 505 506 /* Create the new refcount table and blocks */ 507 uint64_t meta_offset = (blocks_used * s->refcount_block_size) * 508 s->cluster_size; 509 uint64_t table_offset = meta_offset + blocks_clusters * s->cluster_size; 510 uint64_t *new_table = g_try_new0(uint64_t, table_size); 511 void *new_blocks = g_try_malloc0(blocks_clusters * s->cluster_size); 512 513 assert(table_size > 0 && blocks_clusters > 0); 514 if (new_table == NULL || new_blocks == NULL) { 515 ret = -ENOMEM; 516 goto fail_table; 517 } 518 519 /* Fill the new refcount table */ 520 memcpy(new_table, s->refcount_table, 521 s->refcount_table_size * sizeof(uint64_t)); 522 new_table[refcount_table_index] = new_block; 523 524 int i; 525 for (i = 0; i < blocks_clusters; i++) { 526 new_table[blocks_used + i] = meta_offset + (i * s->cluster_size); 527 } 528 529 /* Fill the refcount blocks */ 530 uint64_t table_clusters = size_to_clusters(s, table_size * sizeof(uint64_t)); 531 int block = 0; 532 for (i = 0; i < table_clusters + blocks_clusters; i++) { 533 s->set_refcount(new_blocks, block++, 1); 534 } 535 536 /* Write refcount blocks to disk */ 537 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_WRITE_BLOCKS); 538 ret = bdrv_pwrite_sync(bs->file, meta_offset, new_blocks, 539 blocks_clusters * s->cluster_size); 540 g_free(new_blocks); 541 new_blocks = NULL; 542 if (ret < 0) { 543 goto fail_table; 544 } 545 546 /* Write refcount table to disk */ 547 for(i = 0; i < table_size; i++) { 548 cpu_to_be64s(&new_table[i]); 549 } 550 551 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_WRITE_TABLE); 552 ret = bdrv_pwrite_sync(bs->file, table_offset, new_table, 553 table_size * sizeof(uint64_t)); 554 if (ret < 0) { 555 goto fail_table; 556 } 557 558 for(i = 0; i < table_size; i++) { 559 be64_to_cpus(&new_table[i]); 560 } 561 562 /* Hook up the new refcount table in the qcow2 header */ 563 uint8_t data[12]; 564 cpu_to_be64w((uint64_t*)data, table_offset); 565 cpu_to_be32w((uint32_t*)(data + 8), table_clusters); 566 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_SWITCH_TABLE); 567 ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, refcount_table_offset), 568 data, sizeof(data)); 569 if (ret < 0) { 570 goto fail_table; 571 } 572 573 /* And switch it in memory */ 574 uint64_t old_table_offset = s->refcount_table_offset; 575 uint64_t old_table_size = s->refcount_table_size; 576 577 g_free(s->refcount_table); 578 s->refcount_table = new_table; 579 s->refcount_table_size = table_size; 580 s->refcount_table_offset = table_offset; 581 582 /* Free old table. */ 583 qcow2_free_clusters(bs, old_table_offset, old_table_size * sizeof(uint64_t), 584 QCOW2_DISCARD_OTHER); 585 586 ret = load_refcount_block(bs, new_block, refcount_block); 587 if (ret < 0) { 588 return ret; 589 } 590 591 /* If we were trying to do the initial refcount update for some cluster 592 * allocation, we might have used the same clusters to store newly 593 * allocated metadata. Make the caller search some new space. */ 594 return -EAGAIN; 595 596 fail_table: 597 g_free(new_blocks); 598 g_free(new_table); 599 fail_block: 600 if (*refcount_block != NULL) { 601 qcow2_cache_put(bs, s->refcount_block_cache, refcount_block); 602 } 603 return ret; 604 } 605 606 void qcow2_process_discards(BlockDriverState *bs, int ret) 607 { 608 BDRVQcowState *s = bs->opaque; 609 Qcow2DiscardRegion *d, *next; 610 611 QTAILQ_FOREACH_SAFE(d, &s->discards, next, next) { 612 QTAILQ_REMOVE(&s->discards, d, next); 613 614 /* Discard is optional, ignore the return value */ 615 if (ret >= 0) { 616 bdrv_discard(bs->file, 617 d->offset >> BDRV_SECTOR_BITS, 618 d->bytes >> BDRV_SECTOR_BITS); 619 } 620 621 g_free(d); 622 } 623 } 624 625 static void update_refcount_discard(BlockDriverState *bs, 626 uint64_t offset, uint64_t length) 627 { 628 BDRVQcowState *s = bs->opaque; 629 Qcow2DiscardRegion *d, *p, *next; 630 631 QTAILQ_FOREACH(d, &s->discards, next) { 632 uint64_t new_start = MIN(offset, d->offset); 633 uint64_t new_end = MAX(offset + length, d->offset + d->bytes); 634 635 if (new_end - new_start <= length + d->bytes) { 636 /* There can't be any overlap, areas ending up here have no 637 * references any more and therefore shouldn't get freed another 638 * time. */ 639 assert(d->bytes + length == new_end - new_start); 640 d->offset = new_start; 641 d->bytes = new_end - new_start; 642 goto found; 643 } 644 } 645 646 d = g_malloc(sizeof(*d)); 647 *d = (Qcow2DiscardRegion) { 648 .bs = bs, 649 .offset = offset, 650 .bytes = length, 651 }; 652 QTAILQ_INSERT_TAIL(&s->discards, d, next); 653 654 found: 655 /* Merge discard requests if they are adjacent now */ 656 QTAILQ_FOREACH_SAFE(p, &s->discards, next, next) { 657 if (p == d 658 || p->offset > d->offset + d->bytes 659 || d->offset > p->offset + p->bytes) 660 { 661 continue; 662 } 663 664 /* Still no overlap possible */ 665 assert(p->offset == d->offset + d->bytes 666 || d->offset == p->offset + p->bytes); 667 668 QTAILQ_REMOVE(&s->discards, p, next); 669 d->offset = MIN(d->offset, p->offset); 670 d->bytes += p->bytes; 671 g_free(p); 672 } 673 } 674 675 /* XXX: cache several refcount block clusters ? */ 676 /* @addend is the absolute value of the addend; if @decrease is set, @addend 677 * will be subtracted from the current refcount, otherwise it will be added */ 678 static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs, 679 int64_t offset, 680 int64_t length, 681 uint64_t addend, 682 bool decrease, 683 enum qcow2_discard_type type) 684 { 685 BDRVQcowState *s = bs->opaque; 686 int64_t start, last, cluster_offset; 687 void *refcount_block = NULL; 688 int64_t old_table_index = -1; 689 int ret; 690 691 #ifdef DEBUG_ALLOC2 692 fprintf(stderr, "update_refcount: offset=%" PRId64 " size=%" PRId64 693 " addend=%s%" PRIu64 "\n", offset, length, decrease ? "-" : "", 694 addend); 695 #endif 696 if (length < 0) { 697 return -EINVAL; 698 } else if (length == 0) { 699 return 0; 700 } 701 702 if (decrease) { 703 qcow2_cache_set_dependency(bs, s->refcount_block_cache, 704 s->l2_table_cache); 705 } 706 707 start = start_of_cluster(s, offset); 708 last = start_of_cluster(s, offset + length - 1); 709 for(cluster_offset = start; cluster_offset <= last; 710 cluster_offset += s->cluster_size) 711 { 712 int block_index; 713 uint64_t refcount; 714 int64_t cluster_index = cluster_offset >> s->cluster_bits; 715 int64_t table_index = cluster_index >> s->refcount_block_bits; 716 717 /* Load the refcount block and allocate it if needed */ 718 if (table_index != old_table_index) { 719 if (refcount_block) { 720 qcow2_cache_put(bs, s->refcount_block_cache, &refcount_block); 721 } 722 ret = alloc_refcount_block(bs, cluster_index, &refcount_block); 723 if (ret < 0) { 724 goto fail; 725 } 726 } 727 old_table_index = table_index; 728 729 qcow2_cache_entry_mark_dirty(bs, s->refcount_block_cache, 730 refcount_block); 731 732 /* we can update the count and save it */ 733 block_index = cluster_index & (s->refcount_block_size - 1); 734 735 refcount = s->get_refcount(refcount_block, block_index); 736 if (decrease ? (refcount - addend > refcount) 737 : (refcount + addend < refcount || 738 refcount + addend > s->refcount_max)) 739 { 740 ret = -EINVAL; 741 goto fail; 742 } 743 if (decrease) { 744 refcount -= addend; 745 } else { 746 refcount += addend; 747 } 748 if (refcount == 0 && cluster_index < s->free_cluster_index) { 749 s->free_cluster_index = cluster_index; 750 } 751 s->set_refcount(refcount_block, block_index, refcount); 752 753 if (refcount == 0 && s->discard_passthrough[type]) { 754 update_refcount_discard(bs, cluster_offset, s->cluster_size); 755 } 756 } 757 758 ret = 0; 759 fail: 760 if (!s->cache_discards) { 761 qcow2_process_discards(bs, ret); 762 } 763 764 /* Write last changed block to disk */ 765 if (refcount_block) { 766 qcow2_cache_put(bs, s->refcount_block_cache, &refcount_block); 767 } 768 769 /* 770 * Try do undo any updates if an error is returned (This may succeed in 771 * some cases like ENOSPC for allocating a new refcount block) 772 */ 773 if (ret < 0) { 774 int dummy; 775 dummy = update_refcount(bs, offset, cluster_offset - offset, addend, 776 !decrease, QCOW2_DISCARD_NEVER); 777 (void)dummy; 778 } 779 780 return ret; 781 } 782 783 /* 784 * Increases or decreases the refcount of a given cluster. 785 * 786 * @addend is the absolute value of the addend; if @decrease is set, @addend 787 * will be subtracted from the current refcount, otherwise it will be added. 788 * 789 * On success 0 is returned; on failure -errno is returned. 790 */ 791 int qcow2_update_cluster_refcount(BlockDriverState *bs, 792 int64_t cluster_index, 793 uint64_t addend, bool decrease, 794 enum qcow2_discard_type type) 795 { 796 BDRVQcowState *s = bs->opaque; 797 int ret; 798 799 ret = update_refcount(bs, cluster_index << s->cluster_bits, 1, addend, 800 decrease, type); 801 if (ret < 0) { 802 return ret; 803 } 804 805 return 0; 806 } 807 808 809 810 /*********************************************************/ 811 /* cluster allocation functions */ 812 813 814 815 /* return < 0 if error */ 816 static int64_t alloc_clusters_noref(BlockDriverState *bs, uint64_t size) 817 { 818 BDRVQcowState *s = bs->opaque; 819 uint64_t i, nb_clusters, refcount; 820 int ret; 821 822 /* We can't allocate clusters if they may still be queued for discard. */ 823 if (s->cache_discards) { 824 qcow2_process_discards(bs, 0); 825 } 826 827 nb_clusters = size_to_clusters(s, size); 828 retry: 829 for(i = 0; i < nb_clusters; i++) { 830 uint64_t next_cluster_index = s->free_cluster_index++; 831 ret = qcow2_get_refcount(bs, next_cluster_index, &refcount); 832 833 if (ret < 0) { 834 return ret; 835 } else if (refcount != 0) { 836 goto retry; 837 } 838 } 839 840 /* Make sure that all offsets in the "allocated" range are representable 841 * in an int64_t */ 842 if (s->free_cluster_index > 0 && 843 s->free_cluster_index - 1 > (INT64_MAX >> s->cluster_bits)) 844 { 845 return -EFBIG; 846 } 847 848 #ifdef DEBUG_ALLOC2 849 fprintf(stderr, "alloc_clusters: size=%" PRId64 " -> %" PRId64 "\n", 850 size, 851 (s->free_cluster_index - nb_clusters) << s->cluster_bits); 852 #endif 853 return (s->free_cluster_index - nb_clusters) << s->cluster_bits; 854 } 855 856 int64_t qcow2_alloc_clusters(BlockDriverState *bs, uint64_t size) 857 { 858 int64_t offset; 859 int ret; 860 861 BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_ALLOC); 862 do { 863 offset = alloc_clusters_noref(bs, size); 864 if (offset < 0) { 865 return offset; 866 } 867 868 ret = update_refcount(bs, offset, size, 1, false, QCOW2_DISCARD_NEVER); 869 } while (ret == -EAGAIN); 870 871 if (ret < 0) { 872 return ret; 873 } 874 875 return offset; 876 } 877 878 int qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t offset, 879 int nb_clusters) 880 { 881 BDRVQcowState *s = bs->opaque; 882 uint64_t cluster_index, refcount; 883 uint64_t i; 884 int ret; 885 886 assert(nb_clusters >= 0); 887 if (nb_clusters == 0) { 888 return 0; 889 } 890 891 do { 892 /* Check how many clusters there are free */ 893 cluster_index = offset >> s->cluster_bits; 894 for(i = 0; i < nb_clusters; i++) { 895 ret = qcow2_get_refcount(bs, cluster_index++, &refcount); 896 if (ret < 0) { 897 return ret; 898 } else if (refcount != 0) { 899 break; 900 } 901 } 902 903 /* And then allocate them */ 904 ret = update_refcount(bs, offset, i << s->cluster_bits, 1, false, 905 QCOW2_DISCARD_NEVER); 906 } while (ret == -EAGAIN); 907 908 if (ret < 0) { 909 return ret; 910 } 911 912 return i; 913 } 914 915 /* only used to allocate compressed sectors. We try to allocate 916 contiguous sectors. size must be <= cluster_size */ 917 int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size) 918 { 919 BDRVQcowState *s = bs->opaque; 920 int64_t offset; 921 size_t free_in_cluster; 922 int ret; 923 924 BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_ALLOC_BYTES); 925 assert(size > 0 && size <= s->cluster_size); 926 assert(!s->free_byte_offset || offset_into_cluster(s, s->free_byte_offset)); 927 928 offset = s->free_byte_offset; 929 930 if (offset) { 931 uint64_t refcount; 932 ret = qcow2_get_refcount(bs, offset >> s->cluster_bits, &refcount); 933 if (ret < 0) { 934 return ret; 935 } 936 937 if (refcount == s->refcount_max) { 938 offset = 0; 939 } 940 } 941 942 free_in_cluster = s->cluster_size - offset_into_cluster(s, offset); 943 do { 944 if (!offset || free_in_cluster < size) { 945 int64_t new_cluster = alloc_clusters_noref(bs, s->cluster_size); 946 if (new_cluster < 0) { 947 return new_cluster; 948 } 949 950 if (!offset || ROUND_UP(offset, s->cluster_size) != new_cluster) { 951 offset = new_cluster; 952 } 953 } 954 955 assert(offset); 956 ret = update_refcount(bs, offset, size, 1, false, QCOW2_DISCARD_NEVER); 957 } while (ret == -EAGAIN); 958 if (ret < 0) { 959 return ret; 960 } 961 962 /* The cluster refcount was incremented; refcount blocks must be flushed 963 * before the caller's L2 table updates. */ 964 qcow2_cache_set_dependency(bs, s->l2_table_cache, s->refcount_block_cache); 965 966 s->free_byte_offset = offset + size; 967 if (!offset_into_cluster(s, s->free_byte_offset)) { 968 s->free_byte_offset = 0; 969 } 970 971 return offset; 972 } 973 974 void qcow2_free_clusters(BlockDriverState *bs, 975 int64_t offset, int64_t size, 976 enum qcow2_discard_type type) 977 { 978 int ret; 979 980 BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_FREE); 981 ret = update_refcount(bs, offset, size, 1, true, type); 982 if (ret < 0) { 983 fprintf(stderr, "qcow2_free_clusters failed: %s\n", strerror(-ret)); 984 /* TODO Remember the clusters to free them later and avoid leaking */ 985 } 986 } 987 988 /* 989 * Free a cluster using its L2 entry (handles clusters of all types, e.g. 990 * normal cluster, compressed cluster, etc.) 991 */ 992 void qcow2_free_any_clusters(BlockDriverState *bs, uint64_t l2_entry, 993 int nb_clusters, enum qcow2_discard_type type) 994 { 995 BDRVQcowState *s = bs->opaque; 996 997 switch (qcow2_get_cluster_type(l2_entry)) { 998 case QCOW2_CLUSTER_COMPRESSED: 999 { 1000 int nb_csectors; 1001 nb_csectors = ((l2_entry >> s->csize_shift) & 1002 s->csize_mask) + 1; 1003 qcow2_free_clusters(bs, 1004 (l2_entry & s->cluster_offset_mask) & ~511, 1005 nb_csectors * 512, type); 1006 } 1007 break; 1008 case QCOW2_CLUSTER_NORMAL: 1009 case QCOW2_CLUSTER_ZERO: 1010 if (l2_entry & L2E_OFFSET_MASK) { 1011 if (offset_into_cluster(s, l2_entry & L2E_OFFSET_MASK)) { 1012 qcow2_signal_corruption(bs, false, -1, -1, 1013 "Cannot free unaligned cluster %#llx", 1014 l2_entry & L2E_OFFSET_MASK); 1015 } else { 1016 qcow2_free_clusters(bs, l2_entry & L2E_OFFSET_MASK, 1017 nb_clusters << s->cluster_bits, type); 1018 } 1019 } 1020 break; 1021 case QCOW2_CLUSTER_UNALLOCATED: 1022 break; 1023 default: 1024 abort(); 1025 } 1026 } 1027 1028 1029 1030 /*********************************************************/ 1031 /* snapshots and image creation */ 1032 1033 1034 1035 /* update the refcounts of snapshots and the copied flag */ 1036 int qcow2_update_snapshot_refcount(BlockDriverState *bs, 1037 int64_t l1_table_offset, int l1_size, int addend) 1038 { 1039 BDRVQcowState *s = bs->opaque; 1040 uint64_t *l1_table, *l2_table, l2_offset, offset, l1_size2, refcount; 1041 bool l1_allocated = false; 1042 int64_t old_offset, old_l2_offset; 1043 int i, j, l1_modified = 0, nb_csectors; 1044 int ret; 1045 1046 assert(addend >= -1 && addend <= 1); 1047 1048 l2_table = NULL; 1049 l1_table = NULL; 1050 l1_size2 = l1_size * sizeof(uint64_t); 1051 1052 s->cache_discards = true; 1053 1054 /* WARNING: qcow2_snapshot_goto relies on this function not using the 1055 * l1_table_offset when it is the current s->l1_table_offset! Be careful 1056 * when changing this! */ 1057 if (l1_table_offset != s->l1_table_offset) { 1058 l1_table = g_try_malloc0(align_offset(l1_size2, 512)); 1059 if (l1_size2 && l1_table == NULL) { 1060 ret = -ENOMEM; 1061 goto fail; 1062 } 1063 l1_allocated = true; 1064 1065 ret = bdrv_pread(bs->file, l1_table_offset, l1_table, l1_size2); 1066 if (ret < 0) { 1067 goto fail; 1068 } 1069 1070 for(i = 0;i < l1_size; i++) 1071 be64_to_cpus(&l1_table[i]); 1072 } else { 1073 assert(l1_size == s->l1_size); 1074 l1_table = s->l1_table; 1075 l1_allocated = false; 1076 } 1077 1078 for(i = 0; i < l1_size; i++) { 1079 l2_offset = l1_table[i]; 1080 if (l2_offset) { 1081 old_l2_offset = l2_offset; 1082 l2_offset &= L1E_OFFSET_MASK; 1083 1084 if (offset_into_cluster(s, l2_offset)) { 1085 qcow2_signal_corruption(bs, true, -1, -1, "L2 table offset %#" 1086 PRIx64 " unaligned (L1 index: %#x)", 1087 l2_offset, i); 1088 ret = -EIO; 1089 goto fail; 1090 } 1091 1092 ret = qcow2_cache_get(bs, s->l2_table_cache, l2_offset, 1093 (void**) &l2_table); 1094 if (ret < 0) { 1095 goto fail; 1096 } 1097 1098 for(j = 0; j < s->l2_size; j++) { 1099 uint64_t cluster_index; 1100 1101 offset = be64_to_cpu(l2_table[j]); 1102 old_offset = offset; 1103 offset &= ~QCOW_OFLAG_COPIED; 1104 1105 switch (qcow2_get_cluster_type(offset)) { 1106 case QCOW2_CLUSTER_COMPRESSED: 1107 nb_csectors = ((offset >> s->csize_shift) & 1108 s->csize_mask) + 1; 1109 if (addend != 0) { 1110 ret = update_refcount(bs, 1111 (offset & s->cluster_offset_mask) & ~511, 1112 nb_csectors * 512, abs(addend), addend < 0, 1113 QCOW2_DISCARD_SNAPSHOT); 1114 if (ret < 0) { 1115 goto fail; 1116 } 1117 } 1118 /* compressed clusters are never modified */ 1119 refcount = 2; 1120 break; 1121 1122 case QCOW2_CLUSTER_NORMAL: 1123 case QCOW2_CLUSTER_ZERO: 1124 if (offset_into_cluster(s, offset & L2E_OFFSET_MASK)) { 1125 qcow2_signal_corruption(bs, true, -1, -1, "Data " 1126 "cluster offset %#llx " 1127 "unaligned (L2 offset: %#" 1128 PRIx64 ", L2 index: %#x)", 1129 offset & L2E_OFFSET_MASK, 1130 l2_offset, j); 1131 ret = -EIO; 1132 goto fail; 1133 } 1134 1135 cluster_index = (offset & L2E_OFFSET_MASK) >> s->cluster_bits; 1136 if (!cluster_index) { 1137 /* unallocated */ 1138 refcount = 0; 1139 break; 1140 } 1141 if (addend != 0) { 1142 ret = qcow2_update_cluster_refcount(bs, 1143 cluster_index, abs(addend), addend < 0, 1144 QCOW2_DISCARD_SNAPSHOT); 1145 if (ret < 0) { 1146 goto fail; 1147 } 1148 } 1149 1150 ret = qcow2_get_refcount(bs, cluster_index, &refcount); 1151 if (ret < 0) { 1152 goto fail; 1153 } 1154 break; 1155 1156 case QCOW2_CLUSTER_UNALLOCATED: 1157 refcount = 0; 1158 break; 1159 1160 default: 1161 abort(); 1162 } 1163 1164 if (refcount == 1) { 1165 offset |= QCOW_OFLAG_COPIED; 1166 } 1167 if (offset != old_offset) { 1168 if (addend > 0) { 1169 qcow2_cache_set_dependency(bs, s->l2_table_cache, 1170 s->refcount_block_cache); 1171 } 1172 l2_table[j] = cpu_to_be64(offset); 1173 qcow2_cache_entry_mark_dirty(bs, s->l2_table_cache, 1174 l2_table); 1175 } 1176 } 1177 1178 qcow2_cache_put(bs, s->l2_table_cache, (void **) &l2_table); 1179 1180 if (addend != 0) { 1181 ret = qcow2_update_cluster_refcount(bs, l2_offset >> 1182 s->cluster_bits, 1183 abs(addend), addend < 0, 1184 QCOW2_DISCARD_SNAPSHOT); 1185 if (ret < 0) { 1186 goto fail; 1187 } 1188 } 1189 ret = qcow2_get_refcount(bs, l2_offset >> s->cluster_bits, 1190 &refcount); 1191 if (ret < 0) { 1192 goto fail; 1193 } else if (refcount == 1) { 1194 l2_offset |= QCOW_OFLAG_COPIED; 1195 } 1196 if (l2_offset != old_l2_offset) { 1197 l1_table[i] = l2_offset; 1198 l1_modified = 1; 1199 } 1200 } 1201 } 1202 1203 ret = bdrv_flush(bs); 1204 fail: 1205 if (l2_table) { 1206 qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); 1207 } 1208 1209 s->cache_discards = false; 1210 qcow2_process_discards(bs, ret); 1211 1212 /* Update L1 only if it isn't deleted anyway (addend = -1) */ 1213 if (ret == 0 && addend >= 0 && l1_modified) { 1214 for (i = 0; i < l1_size; i++) { 1215 cpu_to_be64s(&l1_table[i]); 1216 } 1217 1218 ret = bdrv_pwrite_sync(bs->file, l1_table_offset, l1_table, l1_size2); 1219 1220 for (i = 0; i < l1_size; i++) { 1221 be64_to_cpus(&l1_table[i]); 1222 } 1223 } 1224 if (l1_allocated) 1225 g_free(l1_table); 1226 return ret; 1227 } 1228 1229 1230 1231 1232 /*********************************************************/ 1233 /* refcount checking functions */ 1234 1235 1236 static size_t refcount_array_byte_size(BDRVQcowState *s, uint64_t entries) 1237 { 1238 /* This assertion holds because there is no way we can address more than 1239 * 2^(64 - 9) clusters at once (with cluster size 512 = 2^9, and because 1240 * offsets have to be representable in bytes); due to every cluster 1241 * corresponding to one refcount entry, we are well below that limit */ 1242 assert(entries < (UINT64_C(1) << (64 - 9))); 1243 1244 /* Thanks to the assertion this will not overflow, because 1245 * s->refcount_order < 7. 1246 * (note: x << s->refcount_order == x * s->refcount_bits) */ 1247 return DIV_ROUND_UP(entries << s->refcount_order, 8); 1248 } 1249 1250 /** 1251 * Reallocates *array so that it can hold new_size entries. *size must contain 1252 * the current number of entries in *array. If the reallocation fails, *array 1253 * and *size will not be modified and -errno will be returned. If the 1254 * reallocation is successful, *array will be set to the new buffer, *size 1255 * will be set to new_size and 0 will be returned. The size of the reallocated 1256 * refcount array buffer will be aligned to a cluster boundary, and the newly 1257 * allocated area will be zeroed. 1258 */ 1259 static int realloc_refcount_array(BDRVQcowState *s, void **array, 1260 int64_t *size, int64_t new_size) 1261 { 1262 size_t old_byte_size, new_byte_size; 1263 void *new_ptr; 1264 1265 /* Round to clusters so the array can be directly written to disk */ 1266 old_byte_size = size_to_clusters(s, refcount_array_byte_size(s, *size)) 1267 * s->cluster_size; 1268 new_byte_size = size_to_clusters(s, refcount_array_byte_size(s, new_size)) 1269 * s->cluster_size; 1270 1271 if (new_byte_size == old_byte_size) { 1272 *size = new_size; 1273 return 0; 1274 } 1275 1276 assert(new_byte_size > 0); 1277 1278 new_ptr = g_try_realloc(*array, new_byte_size); 1279 if (!new_ptr) { 1280 return -ENOMEM; 1281 } 1282 1283 if (new_byte_size > old_byte_size) { 1284 memset((void *)((uintptr_t)new_ptr + old_byte_size), 0, 1285 new_byte_size - old_byte_size); 1286 } 1287 1288 *array = new_ptr; 1289 *size = new_size; 1290 1291 return 0; 1292 } 1293 1294 /* 1295 * Increases the refcount for a range of clusters in a given refcount table. 1296 * This is used to construct a temporary refcount table out of L1 and L2 tables 1297 * which can be compared the the refcount table saved in the image. 1298 * 1299 * Modifies the number of errors in res. 1300 */ 1301 static int inc_refcounts(BlockDriverState *bs, 1302 BdrvCheckResult *res, 1303 void **refcount_table, 1304 int64_t *refcount_table_size, 1305 int64_t offset, int64_t size) 1306 { 1307 BDRVQcowState *s = bs->opaque; 1308 uint64_t start, last, cluster_offset, k, refcount; 1309 int ret; 1310 1311 if (size <= 0) { 1312 return 0; 1313 } 1314 1315 start = start_of_cluster(s, offset); 1316 last = start_of_cluster(s, offset + size - 1); 1317 for(cluster_offset = start; cluster_offset <= last; 1318 cluster_offset += s->cluster_size) { 1319 k = cluster_offset >> s->cluster_bits; 1320 if (k >= *refcount_table_size) { 1321 ret = realloc_refcount_array(s, refcount_table, 1322 refcount_table_size, k + 1); 1323 if (ret < 0) { 1324 res->check_errors++; 1325 return ret; 1326 } 1327 } 1328 1329 refcount = s->get_refcount(*refcount_table, k); 1330 if (refcount == s->refcount_max) { 1331 fprintf(stderr, "ERROR: overflow cluster offset=0x%" PRIx64 1332 "\n", cluster_offset); 1333 res->corruptions++; 1334 continue; 1335 } 1336 s->set_refcount(*refcount_table, k, refcount + 1); 1337 } 1338 1339 return 0; 1340 } 1341 1342 /* Flags for check_refcounts_l1() and check_refcounts_l2() */ 1343 enum { 1344 CHECK_FRAG_INFO = 0x2, /* update BlockFragInfo counters */ 1345 }; 1346 1347 /* 1348 * Increases the refcount in the given refcount table for the all clusters 1349 * referenced in the L2 table. While doing so, performs some checks on L2 1350 * entries. 1351 * 1352 * Returns the number of errors found by the checks or -errno if an internal 1353 * error occurred. 1354 */ 1355 static int check_refcounts_l2(BlockDriverState *bs, BdrvCheckResult *res, 1356 void **refcount_table, 1357 int64_t *refcount_table_size, int64_t l2_offset, 1358 int flags) 1359 { 1360 BDRVQcowState *s = bs->opaque; 1361 uint64_t *l2_table, l2_entry; 1362 uint64_t next_contiguous_offset = 0; 1363 int i, l2_size, nb_csectors, ret; 1364 1365 /* Read L2 table from disk */ 1366 l2_size = s->l2_size * sizeof(uint64_t); 1367 l2_table = g_malloc(l2_size); 1368 1369 ret = bdrv_pread(bs->file, l2_offset, l2_table, l2_size); 1370 if (ret < 0) { 1371 fprintf(stderr, "ERROR: I/O error in check_refcounts_l2\n"); 1372 res->check_errors++; 1373 goto fail; 1374 } 1375 1376 /* Do the actual checks */ 1377 for(i = 0; i < s->l2_size; i++) { 1378 l2_entry = be64_to_cpu(l2_table[i]); 1379 1380 switch (qcow2_get_cluster_type(l2_entry)) { 1381 case QCOW2_CLUSTER_COMPRESSED: 1382 /* Compressed clusters don't have QCOW_OFLAG_COPIED */ 1383 if (l2_entry & QCOW_OFLAG_COPIED) { 1384 fprintf(stderr, "ERROR: cluster %" PRId64 ": " 1385 "copied flag must never be set for compressed " 1386 "clusters\n", l2_entry >> s->cluster_bits); 1387 l2_entry &= ~QCOW_OFLAG_COPIED; 1388 res->corruptions++; 1389 } 1390 1391 /* Mark cluster as used */ 1392 nb_csectors = ((l2_entry >> s->csize_shift) & 1393 s->csize_mask) + 1; 1394 l2_entry &= s->cluster_offset_mask; 1395 ret = inc_refcounts(bs, res, refcount_table, refcount_table_size, 1396 l2_entry & ~511, nb_csectors * 512); 1397 if (ret < 0) { 1398 goto fail; 1399 } 1400 1401 if (flags & CHECK_FRAG_INFO) { 1402 res->bfi.allocated_clusters++; 1403 res->bfi.compressed_clusters++; 1404 1405 /* Compressed clusters are fragmented by nature. Since they 1406 * take up sub-sector space but we only have sector granularity 1407 * I/O we need to re-read the same sectors even for adjacent 1408 * compressed clusters. 1409 */ 1410 res->bfi.fragmented_clusters++; 1411 } 1412 break; 1413 1414 case QCOW2_CLUSTER_ZERO: 1415 if ((l2_entry & L2E_OFFSET_MASK) == 0) { 1416 break; 1417 } 1418 /* fall through */ 1419 1420 case QCOW2_CLUSTER_NORMAL: 1421 { 1422 uint64_t offset = l2_entry & L2E_OFFSET_MASK; 1423 1424 if (flags & CHECK_FRAG_INFO) { 1425 res->bfi.allocated_clusters++; 1426 if (next_contiguous_offset && 1427 offset != next_contiguous_offset) { 1428 res->bfi.fragmented_clusters++; 1429 } 1430 next_contiguous_offset = offset + s->cluster_size; 1431 } 1432 1433 /* Mark cluster as used */ 1434 ret = inc_refcounts(bs, res, refcount_table, refcount_table_size, 1435 offset, s->cluster_size); 1436 if (ret < 0) { 1437 goto fail; 1438 } 1439 1440 /* Correct offsets are cluster aligned */ 1441 if (offset_into_cluster(s, offset)) { 1442 fprintf(stderr, "ERROR offset=%" PRIx64 ": Cluster is not " 1443 "properly aligned; L2 entry corrupted.\n", offset); 1444 res->corruptions++; 1445 } 1446 break; 1447 } 1448 1449 case QCOW2_CLUSTER_UNALLOCATED: 1450 break; 1451 1452 default: 1453 abort(); 1454 } 1455 } 1456 1457 g_free(l2_table); 1458 return 0; 1459 1460 fail: 1461 g_free(l2_table); 1462 return ret; 1463 } 1464 1465 /* 1466 * Increases the refcount for the L1 table, its L2 tables and all referenced 1467 * clusters in the given refcount table. While doing so, performs some checks 1468 * on L1 and L2 entries. 1469 * 1470 * Returns the number of errors found by the checks or -errno if an internal 1471 * error occurred. 1472 */ 1473 static int check_refcounts_l1(BlockDriverState *bs, 1474 BdrvCheckResult *res, 1475 void **refcount_table, 1476 int64_t *refcount_table_size, 1477 int64_t l1_table_offset, int l1_size, 1478 int flags) 1479 { 1480 BDRVQcowState *s = bs->opaque; 1481 uint64_t *l1_table = NULL, l2_offset, l1_size2; 1482 int i, ret; 1483 1484 l1_size2 = l1_size * sizeof(uint64_t); 1485 1486 /* Mark L1 table as used */ 1487 ret = inc_refcounts(bs, res, refcount_table, refcount_table_size, 1488 l1_table_offset, l1_size2); 1489 if (ret < 0) { 1490 goto fail; 1491 } 1492 1493 /* Read L1 table entries from disk */ 1494 if (l1_size2 > 0) { 1495 l1_table = g_try_malloc(l1_size2); 1496 if (l1_table == NULL) { 1497 ret = -ENOMEM; 1498 res->check_errors++; 1499 goto fail; 1500 } 1501 ret = bdrv_pread(bs->file, l1_table_offset, l1_table, l1_size2); 1502 if (ret < 0) { 1503 fprintf(stderr, "ERROR: I/O error in check_refcounts_l1\n"); 1504 res->check_errors++; 1505 goto fail; 1506 } 1507 for(i = 0;i < l1_size; i++) 1508 be64_to_cpus(&l1_table[i]); 1509 } 1510 1511 /* Do the actual checks */ 1512 for(i = 0; i < l1_size; i++) { 1513 l2_offset = l1_table[i]; 1514 if (l2_offset) { 1515 /* Mark L2 table as used */ 1516 l2_offset &= L1E_OFFSET_MASK; 1517 ret = inc_refcounts(bs, res, refcount_table, refcount_table_size, 1518 l2_offset, s->cluster_size); 1519 if (ret < 0) { 1520 goto fail; 1521 } 1522 1523 /* L2 tables are cluster aligned */ 1524 if (offset_into_cluster(s, l2_offset)) { 1525 fprintf(stderr, "ERROR l2_offset=%" PRIx64 ": Table is not " 1526 "cluster aligned; L1 entry corrupted\n", l2_offset); 1527 res->corruptions++; 1528 } 1529 1530 /* Process and check L2 entries */ 1531 ret = check_refcounts_l2(bs, res, refcount_table, 1532 refcount_table_size, l2_offset, flags); 1533 if (ret < 0) { 1534 goto fail; 1535 } 1536 } 1537 } 1538 g_free(l1_table); 1539 return 0; 1540 1541 fail: 1542 g_free(l1_table); 1543 return ret; 1544 } 1545 1546 /* 1547 * Checks the OFLAG_COPIED flag for all L1 and L2 entries. 1548 * 1549 * This function does not print an error message nor does it increment 1550 * check_errors if qcow2_get_refcount fails (this is because such an error will 1551 * have been already detected and sufficiently signaled by the calling function 1552 * (qcow2_check_refcounts) by the time this function is called). 1553 */ 1554 static int check_oflag_copied(BlockDriverState *bs, BdrvCheckResult *res, 1555 BdrvCheckMode fix) 1556 { 1557 BDRVQcowState *s = bs->opaque; 1558 uint64_t *l2_table = qemu_blockalign(bs, s->cluster_size); 1559 int ret; 1560 uint64_t refcount; 1561 int i, j; 1562 1563 for (i = 0; i < s->l1_size; i++) { 1564 uint64_t l1_entry = s->l1_table[i]; 1565 uint64_t l2_offset = l1_entry & L1E_OFFSET_MASK; 1566 bool l2_dirty = false; 1567 1568 if (!l2_offset) { 1569 continue; 1570 } 1571 1572 ret = qcow2_get_refcount(bs, l2_offset >> s->cluster_bits, 1573 &refcount); 1574 if (ret < 0) { 1575 /* don't print message nor increment check_errors */ 1576 continue; 1577 } 1578 if ((refcount == 1) != ((l1_entry & QCOW_OFLAG_COPIED) != 0)) { 1579 fprintf(stderr, "%s OFLAG_COPIED L2 cluster: l1_index=%d " 1580 "l1_entry=%" PRIx64 " refcount=%" PRIu64 "\n", 1581 fix & BDRV_FIX_ERRORS ? "Repairing" : 1582 "ERROR", 1583 i, l1_entry, refcount); 1584 if (fix & BDRV_FIX_ERRORS) { 1585 s->l1_table[i] = refcount == 1 1586 ? l1_entry | QCOW_OFLAG_COPIED 1587 : l1_entry & ~QCOW_OFLAG_COPIED; 1588 ret = qcow2_write_l1_entry(bs, i); 1589 if (ret < 0) { 1590 res->check_errors++; 1591 goto fail; 1592 } 1593 res->corruptions_fixed++; 1594 } else { 1595 res->corruptions++; 1596 } 1597 } 1598 1599 ret = bdrv_pread(bs->file, l2_offset, l2_table, 1600 s->l2_size * sizeof(uint64_t)); 1601 if (ret < 0) { 1602 fprintf(stderr, "ERROR: Could not read L2 table: %s\n", 1603 strerror(-ret)); 1604 res->check_errors++; 1605 goto fail; 1606 } 1607 1608 for (j = 0; j < s->l2_size; j++) { 1609 uint64_t l2_entry = be64_to_cpu(l2_table[j]); 1610 uint64_t data_offset = l2_entry & L2E_OFFSET_MASK; 1611 int cluster_type = qcow2_get_cluster_type(l2_entry); 1612 1613 if ((cluster_type == QCOW2_CLUSTER_NORMAL) || 1614 ((cluster_type == QCOW2_CLUSTER_ZERO) && (data_offset != 0))) { 1615 ret = qcow2_get_refcount(bs, 1616 data_offset >> s->cluster_bits, 1617 &refcount); 1618 if (ret < 0) { 1619 /* don't print message nor increment check_errors */ 1620 continue; 1621 } 1622 if ((refcount == 1) != ((l2_entry & QCOW_OFLAG_COPIED) != 0)) { 1623 fprintf(stderr, "%s OFLAG_COPIED data cluster: " 1624 "l2_entry=%" PRIx64 " refcount=%" PRIu64 "\n", 1625 fix & BDRV_FIX_ERRORS ? "Repairing" : 1626 "ERROR", 1627 l2_entry, refcount); 1628 if (fix & BDRV_FIX_ERRORS) { 1629 l2_table[j] = cpu_to_be64(refcount == 1 1630 ? l2_entry | QCOW_OFLAG_COPIED 1631 : l2_entry & ~QCOW_OFLAG_COPIED); 1632 l2_dirty = true; 1633 res->corruptions_fixed++; 1634 } else { 1635 res->corruptions++; 1636 } 1637 } 1638 } 1639 } 1640 1641 if (l2_dirty) { 1642 ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_ACTIVE_L2, 1643 l2_offset, s->cluster_size); 1644 if (ret < 0) { 1645 fprintf(stderr, "ERROR: Could not write L2 table; metadata " 1646 "overlap check failed: %s\n", strerror(-ret)); 1647 res->check_errors++; 1648 goto fail; 1649 } 1650 1651 ret = bdrv_pwrite(bs->file, l2_offset, l2_table, s->cluster_size); 1652 if (ret < 0) { 1653 fprintf(stderr, "ERROR: Could not write L2 table: %s\n", 1654 strerror(-ret)); 1655 res->check_errors++; 1656 goto fail; 1657 } 1658 } 1659 } 1660 1661 ret = 0; 1662 1663 fail: 1664 qemu_vfree(l2_table); 1665 return ret; 1666 } 1667 1668 /* 1669 * Checks consistency of refblocks and accounts for each refblock in 1670 * *refcount_table. 1671 */ 1672 static int check_refblocks(BlockDriverState *bs, BdrvCheckResult *res, 1673 BdrvCheckMode fix, bool *rebuild, 1674 void **refcount_table, int64_t *nb_clusters) 1675 { 1676 BDRVQcowState *s = bs->opaque; 1677 int64_t i, size; 1678 int ret; 1679 1680 for(i = 0; i < s->refcount_table_size; i++) { 1681 uint64_t offset, cluster; 1682 offset = s->refcount_table[i]; 1683 cluster = offset >> s->cluster_bits; 1684 1685 /* Refcount blocks are cluster aligned */ 1686 if (offset_into_cluster(s, offset)) { 1687 fprintf(stderr, "ERROR refcount block %" PRId64 " is not " 1688 "cluster aligned; refcount table entry corrupted\n", i); 1689 res->corruptions++; 1690 *rebuild = true; 1691 continue; 1692 } 1693 1694 if (cluster >= *nb_clusters) { 1695 fprintf(stderr, "%s refcount block %" PRId64 " is outside image\n", 1696 fix & BDRV_FIX_ERRORS ? "Repairing" : "ERROR", i); 1697 1698 if (fix & BDRV_FIX_ERRORS) { 1699 int64_t new_nb_clusters; 1700 1701 if (offset > INT64_MAX - s->cluster_size) { 1702 ret = -EINVAL; 1703 goto resize_fail; 1704 } 1705 1706 ret = bdrv_truncate(bs->file, offset + s->cluster_size); 1707 if (ret < 0) { 1708 goto resize_fail; 1709 } 1710 size = bdrv_getlength(bs->file); 1711 if (size < 0) { 1712 ret = size; 1713 goto resize_fail; 1714 } 1715 1716 new_nb_clusters = size_to_clusters(s, size); 1717 assert(new_nb_clusters >= *nb_clusters); 1718 1719 ret = realloc_refcount_array(s, refcount_table, 1720 nb_clusters, new_nb_clusters); 1721 if (ret < 0) { 1722 res->check_errors++; 1723 return ret; 1724 } 1725 1726 if (cluster >= *nb_clusters) { 1727 ret = -EINVAL; 1728 goto resize_fail; 1729 } 1730 1731 res->corruptions_fixed++; 1732 ret = inc_refcounts(bs, res, refcount_table, nb_clusters, 1733 offset, s->cluster_size); 1734 if (ret < 0) { 1735 return ret; 1736 } 1737 /* No need to check whether the refcount is now greater than 1: 1738 * This area was just allocated and zeroed, so it can only be 1739 * exactly 1 after inc_refcounts() */ 1740 continue; 1741 1742 resize_fail: 1743 res->corruptions++; 1744 *rebuild = true; 1745 fprintf(stderr, "ERROR could not resize image: %s\n", 1746 strerror(-ret)); 1747 } else { 1748 res->corruptions++; 1749 } 1750 continue; 1751 } 1752 1753 if (offset != 0) { 1754 ret = inc_refcounts(bs, res, refcount_table, nb_clusters, 1755 offset, s->cluster_size); 1756 if (ret < 0) { 1757 return ret; 1758 } 1759 if (s->get_refcount(*refcount_table, cluster) != 1) { 1760 fprintf(stderr, "ERROR refcount block %" PRId64 1761 " refcount=%" PRIu64 "\n", i, 1762 s->get_refcount(*refcount_table, cluster)); 1763 res->corruptions++; 1764 *rebuild = true; 1765 } 1766 } 1767 } 1768 1769 return 0; 1770 } 1771 1772 /* 1773 * Calculates an in-memory refcount table. 1774 */ 1775 static int calculate_refcounts(BlockDriverState *bs, BdrvCheckResult *res, 1776 BdrvCheckMode fix, bool *rebuild, 1777 void **refcount_table, int64_t *nb_clusters) 1778 { 1779 BDRVQcowState *s = bs->opaque; 1780 int64_t i; 1781 QCowSnapshot *sn; 1782 int ret; 1783 1784 if (!*refcount_table) { 1785 int64_t old_size = 0; 1786 ret = realloc_refcount_array(s, refcount_table, 1787 &old_size, *nb_clusters); 1788 if (ret < 0) { 1789 res->check_errors++; 1790 return ret; 1791 } 1792 } 1793 1794 /* header */ 1795 ret = inc_refcounts(bs, res, refcount_table, nb_clusters, 1796 0, s->cluster_size); 1797 if (ret < 0) { 1798 return ret; 1799 } 1800 1801 /* current L1 table */ 1802 ret = check_refcounts_l1(bs, res, refcount_table, nb_clusters, 1803 s->l1_table_offset, s->l1_size, CHECK_FRAG_INFO); 1804 if (ret < 0) { 1805 return ret; 1806 } 1807 1808 /* snapshots */ 1809 for (i = 0; i < s->nb_snapshots; i++) { 1810 sn = s->snapshots + i; 1811 ret = check_refcounts_l1(bs, res, refcount_table, nb_clusters, 1812 sn->l1_table_offset, sn->l1_size, 0); 1813 if (ret < 0) { 1814 return ret; 1815 } 1816 } 1817 ret = inc_refcounts(bs, res, refcount_table, nb_clusters, 1818 s->snapshots_offset, s->snapshots_size); 1819 if (ret < 0) { 1820 return ret; 1821 } 1822 1823 /* refcount data */ 1824 ret = inc_refcounts(bs, res, refcount_table, nb_clusters, 1825 s->refcount_table_offset, 1826 s->refcount_table_size * sizeof(uint64_t)); 1827 if (ret < 0) { 1828 return ret; 1829 } 1830 1831 return check_refblocks(bs, res, fix, rebuild, refcount_table, nb_clusters); 1832 } 1833 1834 /* 1835 * Compares the actual reference count for each cluster in the image against the 1836 * refcount as reported by the refcount structures on-disk. 1837 */ 1838 static void compare_refcounts(BlockDriverState *bs, BdrvCheckResult *res, 1839 BdrvCheckMode fix, bool *rebuild, 1840 int64_t *highest_cluster, 1841 void *refcount_table, int64_t nb_clusters) 1842 { 1843 BDRVQcowState *s = bs->opaque; 1844 int64_t i; 1845 uint64_t refcount1, refcount2; 1846 int ret; 1847 1848 for (i = 0, *highest_cluster = 0; i < nb_clusters; i++) { 1849 ret = qcow2_get_refcount(bs, i, &refcount1); 1850 if (ret < 0) { 1851 fprintf(stderr, "Can't get refcount for cluster %" PRId64 ": %s\n", 1852 i, strerror(-ret)); 1853 res->check_errors++; 1854 continue; 1855 } 1856 1857 refcount2 = s->get_refcount(refcount_table, i); 1858 1859 if (refcount1 > 0 || refcount2 > 0) { 1860 *highest_cluster = i; 1861 } 1862 1863 if (refcount1 != refcount2) { 1864 /* Check if we're allowed to fix the mismatch */ 1865 int *num_fixed = NULL; 1866 if (refcount1 == 0) { 1867 *rebuild = true; 1868 } else if (refcount1 > refcount2 && (fix & BDRV_FIX_LEAKS)) { 1869 num_fixed = &res->leaks_fixed; 1870 } else if (refcount1 < refcount2 && (fix & BDRV_FIX_ERRORS)) { 1871 num_fixed = &res->corruptions_fixed; 1872 } 1873 1874 fprintf(stderr, "%s cluster %" PRId64 " refcount=%" PRIu64 1875 " reference=%" PRIu64 "\n", 1876 num_fixed != NULL ? "Repairing" : 1877 refcount1 < refcount2 ? "ERROR" : 1878 "Leaked", 1879 i, refcount1, refcount2); 1880 1881 if (num_fixed) { 1882 ret = update_refcount(bs, i << s->cluster_bits, 1, 1883 refcount_diff(refcount1, refcount2), 1884 refcount1 > refcount2, 1885 QCOW2_DISCARD_ALWAYS); 1886 if (ret >= 0) { 1887 (*num_fixed)++; 1888 continue; 1889 } 1890 } 1891 1892 /* And if we couldn't, print an error */ 1893 if (refcount1 < refcount2) { 1894 res->corruptions++; 1895 } else { 1896 res->leaks++; 1897 } 1898 } 1899 } 1900 } 1901 1902 /* 1903 * Allocates clusters using an in-memory refcount table (IMRT) in contrast to 1904 * the on-disk refcount structures. 1905 * 1906 * On input, *first_free_cluster tells where to start looking, and need not 1907 * actually be a free cluster; the returned offset will not be before that 1908 * cluster. On output, *first_free_cluster points to the first gap found, even 1909 * if that gap was too small to be used as the returned offset. 1910 * 1911 * Note that *first_free_cluster is a cluster index whereas the return value is 1912 * an offset. 1913 */ 1914 static int64_t alloc_clusters_imrt(BlockDriverState *bs, 1915 int cluster_count, 1916 void **refcount_table, 1917 int64_t *imrt_nb_clusters, 1918 int64_t *first_free_cluster) 1919 { 1920 BDRVQcowState *s = bs->opaque; 1921 int64_t cluster = *first_free_cluster, i; 1922 bool first_gap = true; 1923 int contiguous_free_clusters; 1924 int ret; 1925 1926 /* Starting at *first_free_cluster, find a range of at least cluster_count 1927 * continuously free clusters */ 1928 for (contiguous_free_clusters = 0; 1929 cluster < *imrt_nb_clusters && 1930 contiguous_free_clusters < cluster_count; 1931 cluster++) 1932 { 1933 if (!s->get_refcount(*refcount_table, cluster)) { 1934 contiguous_free_clusters++; 1935 if (first_gap) { 1936 /* If this is the first free cluster found, update 1937 * *first_free_cluster accordingly */ 1938 *first_free_cluster = cluster; 1939 first_gap = false; 1940 } 1941 } else if (contiguous_free_clusters) { 1942 contiguous_free_clusters = 0; 1943 } 1944 } 1945 1946 /* If contiguous_free_clusters is greater than zero, it contains the number 1947 * of continuously free clusters until the current cluster; the first free 1948 * cluster in the current "gap" is therefore 1949 * cluster - contiguous_free_clusters */ 1950 1951 /* If no such range could be found, grow the in-memory refcount table 1952 * accordingly to append free clusters at the end of the image */ 1953 if (contiguous_free_clusters < cluster_count) { 1954 /* contiguous_free_clusters clusters are already empty at the image end; 1955 * we need cluster_count clusters; therefore, we have to allocate 1956 * cluster_count - contiguous_free_clusters new clusters at the end of 1957 * the image (which is the current value of cluster; note that cluster 1958 * may exceed old_imrt_nb_clusters if *first_free_cluster pointed beyond 1959 * the image end) */ 1960 ret = realloc_refcount_array(s, refcount_table, imrt_nb_clusters, 1961 cluster + cluster_count 1962 - contiguous_free_clusters); 1963 if (ret < 0) { 1964 return ret; 1965 } 1966 } 1967 1968 /* Go back to the first free cluster */ 1969 cluster -= contiguous_free_clusters; 1970 for (i = 0; i < cluster_count; i++) { 1971 s->set_refcount(*refcount_table, cluster + i, 1); 1972 } 1973 1974 return cluster << s->cluster_bits; 1975 } 1976 1977 /* 1978 * Creates a new refcount structure based solely on the in-memory information 1979 * given through *refcount_table. All necessary allocations will be reflected 1980 * in that array. 1981 * 1982 * On success, the old refcount structure is leaked (it will be covered by the 1983 * new refcount structure). 1984 */ 1985 static int rebuild_refcount_structure(BlockDriverState *bs, 1986 BdrvCheckResult *res, 1987 void **refcount_table, 1988 int64_t *nb_clusters) 1989 { 1990 BDRVQcowState *s = bs->opaque; 1991 int64_t first_free_cluster = 0, reftable_offset = -1, cluster = 0; 1992 int64_t refblock_offset, refblock_start, refblock_index; 1993 uint32_t reftable_size = 0; 1994 uint64_t *on_disk_reftable = NULL; 1995 void *on_disk_refblock; 1996 int ret = 0; 1997 struct { 1998 uint64_t reftable_offset; 1999 uint32_t reftable_clusters; 2000 } QEMU_PACKED reftable_offset_and_clusters; 2001 2002 qcow2_cache_empty(bs, s->refcount_block_cache); 2003 2004 write_refblocks: 2005 for (; cluster < *nb_clusters; cluster++) { 2006 if (!s->get_refcount(*refcount_table, cluster)) { 2007 continue; 2008 } 2009 2010 refblock_index = cluster >> s->refcount_block_bits; 2011 refblock_start = refblock_index << s->refcount_block_bits; 2012 2013 /* Don't allocate a cluster in a refblock already written to disk */ 2014 if (first_free_cluster < refblock_start) { 2015 first_free_cluster = refblock_start; 2016 } 2017 refblock_offset = alloc_clusters_imrt(bs, 1, refcount_table, 2018 nb_clusters, &first_free_cluster); 2019 if (refblock_offset < 0) { 2020 fprintf(stderr, "ERROR allocating refblock: %s\n", 2021 strerror(-refblock_offset)); 2022 res->check_errors++; 2023 ret = refblock_offset; 2024 goto fail; 2025 } 2026 2027 if (reftable_size <= refblock_index) { 2028 uint32_t old_reftable_size = reftable_size; 2029 uint64_t *new_on_disk_reftable; 2030 2031 reftable_size = ROUND_UP((refblock_index + 1) * sizeof(uint64_t), 2032 s->cluster_size) / sizeof(uint64_t); 2033 new_on_disk_reftable = g_try_realloc(on_disk_reftable, 2034 reftable_size * 2035 sizeof(uint64_t)); 2036 if (!new_on_disk_reftable) { 2037 res->check_errors++; 2038 ret = -ENOMEM; 2039 goto fail; 2040 } 2041 on_disk_reftable = new_on_disk_reftable; 2042 2043 memset(on_disk_reftable + old_reftable_size, 0, 2044 (reftable_size - old_reftable_size) * sizeof(uint64_t)); 2045 2046 /* The offset we have for the reftable is now no longer valid; 2047 * this will leak that range, but we can easily fix that by running 2048 * a leak-fixing check after this rebuild operation */ 2049 reftable_offset = -1; 2050 } 2051 on_disk_reftable[refblock_index] = refblock_offset; 2052 2053 /* If this is apparently the last refblock (for now), try to squeeze the 2054 * reftable in */ 2055 if (refblock_index == (*nb_clusters - 1) >> s->refcount_block_bits && 2056 reftable_offset < 0) 2057 { 2058 uint64_t reftable_clusters = size_to_clusters(s, reftable_size * 2059 sizeof(uint64_t)); 2060 reftable_offset = alloc_clusters_imrt(bs, reftable_clusters, 2061 refcount_table, nb_clusters, 2062 &first_free_cluster); 2063 if (reftable_offset < 0) { 2064 fprintf(stderr, "ERROR allocating reftable: %s\n", 2065 strerror(-reftable_offset)); 2066 res->check_errors++; 2067 ret = reftable_offset; 2068 goto fail; 2069 } 2070 } 2071 2072 ret = qcow2_pre_write_overlap_check(bs, 0, refblock_offset, 2073 s->cluster_size); 2074 if (ret < 0) { 2075 fprintf(stderr, "ERROR writing refblock: %s\n", strerror(-ret)); 2076 goto fail; 2077 } 2078 2079 /* The size of *refcount_table is always cluster-aligned, therefore the 2080 * write operation will not overflow */ 2081 on_disk_refblock = (void *)((char *) *refcount_table + 2082 refblock_index * s->cluster_size); 2083 2084 ret = bdrv_write(bs->file, refblock_offset / BDRV_SECTOR_SIZE, 2085 on_disk_refblock, s->cluster_sectors); 2086 if (ret < 0) { 2087 fprintf(stderr, "ERROR writing refblock: %s\n", strerror(-ret)); 2088 goto fail; 2089 } 2090 2091 /* Go to the end of this refblock */ 2092 cluster = refblock_start + s->refcount_block_size - 1; 2093 } 2094 2095 if (reftable_offset < 0) { 2096 uint64_t post_refblock_start, reftable_clusters; 2097 2098 post_refblock_start = ROUND_UP(*nb_clusters, s->refcount_block_size); 2099 reftable_clusters = size_to_clusters(s, 2100 reftable_size * sizeof(uint64_t)); 2101 /* Not pretty but simple */ 2102 if (first_free_cluster < post_refblock_start) { 2103 first_free_cluster = post_refblock_start; 2104 } 2105 reftable_offset = alloc_clusters_imrt(bs, reftable_clusters, 2106 refcount_table, nb_clusters, 2107 &first_free_cluster); 2108 if (reftable_offset < 0) { 2109 fprintf(stderr, "ERROR allocating reftable: %s\n", 2110 strerror(-reftable_offset)); 2111 res->check_errors++; 2112 ret = reftable_offset; 2113 goto fail; 2114 } 2115 2116 goto write_refblocks; 2117 } 2118 2119 assert(on_disk_reftable); 2120 2121 for (refblock_index = 0; refblock_index < reftable_size; refblock_index++) { 2122 cpu_to_be64s(&on_disk_reftable[refblock_index]); 2123 } 2124 2125 ret = qcow2_pre_write_overlap_check(bs, 0, reftable_offset, 2126 reftable_size * sizeof(uint64_t)); 2127 if (ret < 0) { 2128 fprintf(stderr, "ERROR writing reftable: %s\n", strerror(-ret)); 2129 goto fail; 2130 } 2131 2132 assert(reftable_size < INT_MAX / sizeof(uint64_t)); 2133 ret = bdrv_pwrite(bs->file, reftable_offset, on_disk_reftable, 2134 reftable_size * sizeof(uint64_t)); 2135 if (ret < 0) { 2136 fprintf(stderr, "ERROR writing reftable: %s\n", strerror(-ret)); 2137 goto fail; 2138 } 2139 2140 /* Enter new reftable into the image header */ 2141 cpu_to_be64w(&reftable_offset_and_clusters.reftable_offset, 2142 reftable_offset); 2143 cpu_to_be32w(&reftable_offset_and_clusters.reftable_clusters, 2144 size_to_clusters(s, reftable_size * sizeof(uint64_t))); 2145 ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, 2146 refcount_table_offset), 2147 &reftable_offset_and_clusters, 2148 sizeof(reftable_offset_and_clusters)); 2149 if (ret < 0) { 2150 fprintf(stderr, "ERROR setting reftable: %s\n", strerror(-ret)); 2151 goto fail; 2152 } 2153 2154 for (refblock_index = 0; refblock_index < reftable_size; refblock_index++) { 2155 be64_to_cpus(&on_disk_reftable[refblock_index]); 2156 } 2157 s->refcount_table = on_disk_reftable; 2158 s->refcount_table_offset = reftable_offset; 2159 s->refcount_table_size = reftable_size; 2160 2161 return 0; 2162 2163 fail: 2164 g_free(on_disk_reftable); 2165 return ret; 2166 } 2167 2168 /* 2169 * Checks an image for refcount consistency. 2170 * 2171 * Returns 0 if no errors are found, the number of errors in case the image is 2172 * detected as corrupted, and -errno when an internal error occurred. 2173 */ 2174 int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res, 2175 BdrvCheckMode fix) 2176 { 2177 BDRVQcowState *s = bs->opaque; 2178 BdrvCheckResult pre_compare_res; 2179 int64_t size, highest_cluster, nb_clusters; 2180 void *refcount_table = NULL; 2181 bool rebuild = false; 2182 int ret; 2183 2184 size = bdrv_getlength(bs->file); 2185 if (size < 0) { 2186 res->check_errors++; 2187 return size; 2188 } 2189 2190 nb_clusters = size_to_clusters(s, size); 2191 if (nb_clusters > INT_MAX) { 2192 res->check_errors++; 2193 return -EFBIG; 2194 } 2195 2196 res->bfi.total_clusters = 2197 size_to_clusters(s, bs->total_sectors * BDRV_SECTOR_SIZE); 2198 2199 ret = calculate_refcounts(bs, res, fix, &rebuild, &refcount_table, 2200 &nb_clusters); 2201 if (ret < 0) { 2202 goto fail; 2203 } 2204 2205 /* In case we don't need to rebuild the refcount structure (but want to fix 2206 * something), this function is immediately called again, in which case the 2207 * result should be ignored */ 2208 pre_compare_res = *res; 2209 compare_refcounts(bs, res, 0, &rebuild, &highest_cluster, refcount_table, 2210 nb_clusters); 2211 2212 if (rebuild && (fix & BDRV_FIX_ERRORS)) { 2213 BdrvCheckResult old_res = *res; 2214 int fresh_leaks = 0; 2215 2216 fprintf(stderr, "Rebuilding refcount structure\n"); 2217 ret = rebuild_refcount_structure(bs, res, &refcount_table, 2218 &nb_clusters); 2219 if (ret < 0) { 2220 goto fail; 2221 } 2222 2223 res->corruptions = 0; 2224 res->leaks = 0; 2225 2226 /* Because the old reftable has been exchanged for a new one the 2227 * references have to be recalculated */ 2228 rebuild = false; 2229 memset(refcount_table, 0, refcount_array_byte_size(s, nb_clusters)); 2230 ret = calculate_refcounts(bs, res, 0, &rebuild, &refcount_table, 2231 &nb_clusters); 2232 if (ret < 0) { 2233 goto fail; 2234 } 2235 2236 if (fix & BDRV_FIX_LEAKS) { 2237 /* The old refcount structures are now leaked, fix it; the result 2238 * can be ignored, aside from leaks which were introduced by 2239 * rebuild_refcount_structure() that could not be fixed */ 2240 BdrvCheckResult saved_res = *res; 2241 *res = (BdrvCheckResult){ 0 }; 2242 2243 compare_refcounts(bs, res, BDRV_FIX_LEAKS, &rebuild, 2244 &highest_cluster, refcount_table, nb_clusters); 2245 if (rebuild) { 2246 fprintf(stderr, "ERROR rebuilt refcount structure is still " 2247 "broken\n"); 2248 } 2249 2250 /* Any leaks accounted for here were introduced by 2251 * rebuild_refcount_structure() because that function has created a 2252 * new refcount structure from scratch */ 2253 fresh_leaks = res->leaks; 2254 *res = saved_res; 2255 } 2256 2257 if (res->corruptions < old_res.corruptions) { 2258 res->corruptions_fixed += old_res.corruptions - res->corruptions; 2259 } 2260 if (res->leaks < old_res.leaks) { 2261 res->leaks_fixed += old_res.leaks - res->leaks; 2262 } 2263 res->leaks += fresh_leaks; 2264 } else if (fix) { 2265 if (rebuild) { 2266 fprintf(stderr, "ERROR need to rebuild refcount structures\n"); 2267 res->check_errors++; 2268 ret = -EIO; 2269 goto fail; 2270 } 2271 2272 if (res->leaks || res->corruptions) { 2273 *res = pre_compare_res; 2274 compare_refcounts(bs, res, fix, &rebuild, &highest_cluster, 2275 refcount_table, nb_clusters); 2276 } 2277 } 2278 2279 /* check OFLAG_COPIED */ 2280 ret = check_oflag_copied(bs, res, fix); 2281 if (ret < 0) { 2282 goto fail; 2283 } 2284 2285 res->image_end_offset = (highest_cluster + 1) * s->cluster_size; 2286 ret = 0; 2287 2288 fail: 2289 g_free(refcount_table); 2290 2291 return ret; 2292 } 2293 2294 #define overlaps_with(ofs, sz) \ 2295 ranges_overlap(offset, size, ofs, sz) 2296 2297 /* 2298 * Checks if the given offset into the image file is actually free to use by 2299 * looking for overlaps with important metadata sections (L1/L2 tables etc.), 2300 * i.e. a sanity check without relying on the refcount tables. 2301 * 2302 * The ign parameter specifies what checks not to perform (being a bitmask of 2303 * QCow2MetadataOverlap values), i.e., what sections to ignore. 2304 * 2305 * Returns: 2306 * - 0 if writing to this offset will not affect the mentioned metadata 2307 * - a positive QCow2MetadataOverlap value indicating one overlapping section 2308 * - a negative value (-errno) indicating an error while performing a check, 2309 * e.g. when bdrv_read failed on QCOW2_OL_INACTIVE_L2 2310 */ 2311 int qcow2_check_metadata_overlap(BlockDriverState *bs, int ign, int64_t offset, 2312 int64_t size) 2313 { 2314 BDRVQcowState *s = bs->opaque; 2315 int chk = s->overlap_check & ~ign; 2316 int i, j; 2317 2318 if (!size) { 2319 return 0; 2320 } 2321 2322 if (chk & QCOW2_OL_MAIN_HEADER) { 2323 if (offset < s->cluster_size) { 2324 return QCOW2_OL_MAIN_HEADER; 2325 } 2326 } 2327 2328 /* align range to test to cluster boundaries */ 2329 size = align_offset(offset_into_cluster(s, offset) + size, s->cluster_size); 2330 offset = start_of_cluster(s, offset); 2331 2332 if ((chk & QCOW2_OL_ACTIVE_L1) && s->l1_size) { 2333 if (overlaps_with(s->l1_table_offset, s->l1_size * sizeof(uint64_t))) { 2334 return QCOW2_OL_ACTIVE_L1; 2335 } 2336 } 2337 2338 if ((chk & QCOW2_OL_REFCOUNT_TABLE) && s->refcount_table_size) { 2339 if (overlaps_with(s->refcount_table_offset, 2340 s->refcount_table_size * sizeof(uint64_t))) { 2341 return QCOW2_OL_REFCOUNT_TABLE; 2342 } 2343 } 2344 2345 if ((chk & QCOW2_OL_SNAPSHOT_TABLE) && s->snapshots_size) { 2346 if (overlaps_with(s->snapshots_offset, s->snapshots_size)) { 2347 return QCOW2_OL_SNAPSHOT_TABLE; 2348 } 2349 } 2350 2351 if ((chk & QCOW2_OL_INACTIVE_L1) && s->snapshots) { 2352 for (i = 0; i < s->nb_snapshots; i++) { 2353 if (s->snapshots[i].l1_size && 2354 overlaps_with(s->snapshots[i].l1_table_offset, 2355 s->snapshots[i].l1_size * sizeof(uint64_t))) { 2356 return QCOW2_OL_INACTIVE_L1; 2357 } 2358 } 2359 } 2360 2361 if ((chk & QCOW2_OL_ACTIVE_L2) && s->l1_table) { 2362 for (i = 0; i < s->l1_size; i++) { 2363 if ((s->l1_table[i] & L1E_OFFSET_MASK) && 2364 overlaps_with(s->l1_table[i] & L1E_OFFSET_MASK, 2365 s->cluster_size)) { 2366 return QCOW2_OL_ACTIVE_L2; 2367 } 2368 } 2369 } 2370 2371 if ((chk & QCOW2_OL_REFCOUNT_BLOCK) && s->refcount_table) { 2372 for (i = 0; i < s->refcount_table_size; i++) { 2373 if ((s->refcount_table[i] & REFT_OFFSET_MASK) && 2374 overlaps_with(s->refcount_table[i] & REFT_OFFSET_MASK, 2375 s->cluster_size)) { 2376 return QCOW2_OL_REFCOUNT_BLOCK; 2377 } 2378 } 2379 } 2380 2381 if ((chk & QCOW2_OL_INACTIVE_L2) && s->snapshots) { 2382 for (i = 0; i < s->nb_snapshots; i++) { 2383 uint64_t l1_ofs = s->snapshots[i].l1_table_offset; 2384 uint32_t l1_sz = s->snapshots[i].l1_size; 2385 uint64_t l1_sz2 = l1_sz * sizeof(uint64_t); 2386 uint64_t *l1 = g_try_malloc(l1_sz2); 2387 int ret; 2388 2389 if (l1_sz2 && l1 == NULL) { 2390 return -ENOMEM; 2391 } 2392 2393 ret = bdrv_pread(bs->file, l1_ofs, l1, l1_sz2); 2394 if (ret < 0) { 2395 g_free(l1); 2396 return ret; 2397 } 2398 2399 for (j = 0; j < l1_sz; j++) { 2400 uint64_t l2_ofs = be64_to_cpu(l1[j]) & L1E_OFFSET_MASK; 2401 if (l2_ofs && overlaps_with(l2_ofs, s->cluster_size)) { 2402 g_free(l1); 2403 return QCOW2_OL_INACTIVE_L2; 2404 } 2405 } 2406 2407 g_free(l1); 2408 } 2409 } 2410 2411 return 0; 2412 } 2413 2414 static const char *metadata_ol_names[] = { 2415 [QCOW2_OL_MAIN_HEADER_BITNR] = "qcow2_header", 2416 [QCOW2_OL_ACTIVE_L1_BITNR] = "active L1 table", 2417 [QCOW2_OL_ACTIVE_L2_BITNR] = "active L2 table", 2418 [QCOW2_OL_REFCOUNT_TABLE_BITNR] = "refcount table", 2419 [QCOW2_OL_REFCOUNT_BLOCK_BITNR] = "refcount block", 2420 [QCOW2_OL_SNAPSHOT_TABLE_BITNR] = "snapshot table", 2421 [QCOW2_OL_INACTIVE_L1_BITNR] = "inactive L1 table", 2422 [QCOW2_OL_INACTIVE_L2_BITNR] = "inactive L2 table", 2423 }; 2424 2425 /* 2426 * First performs a check for metadata overlaps (through 2427 * qcow2_check_metadata_overlap); if that fails with a negative value (error 2428 * while performing a check), that value is returned. If an impending overlap 2429 * is detected, the BDS will be made unusable, the qcow2 file marked corrupt 2430 * and -EIO returned. 2431 * 2432 * Returns 0 if there were neither overlaps nor errors while checking for 2433 * overlaps; or a negative value (-errno) on error. 2434 */ 2435 int qcow2_pre_write_overlap_check(BlockDriverState *bs, int ign, int64_t offset, 2436 int64_t size) 2437 { 2438 int ret = qcow2_check_metadata_overlap(bs, ign, offset, size); 2439 2440 if (ret < 0) { 2441 return ret; 2442 } else if (ret > 0) { 2443 int metadata_ol_bitnr = ctz32(ret); 2444 assert(metadata_ol_bitnr < QCOW2_OL_MAX_BITNR); 2445 2446 qcow2_signal_corruption(bs, true, offset, size, "Preventing invalid " 2447 "write on metadata (overlaps with %s)", 2448 metadata_ol_names[metadata_ol_bitnr]); 2449 return -EIO; 2450 } 2451 2452 return 0; 2453 } 2454