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/osdep.h" 26 #include "qapi/error.h" 27 #include "qcow2.h" 28 #include "qemu/range.h" 29 #include "qemu/bswap.h" 30 #include "qemu/cutils.h" 31 #include "trace.h" 32 33 static int64_t alloc_clusters_noref(BlockDriverState *bs, uint64_t size, 34 uint64_t max); 35 static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs, 36 int64_t offset, int64_t length, uint64_t addend, 37 bool decrease, enum qcow2_discard_type type); 38 39 static uint64_t get_refcount_ro0(const void *refcount_array, uint64_t index); 40 static uint64_t get_refcount_ro1(const void *refcount_array, uint64_t index); 41 static uint64_t get_refcount_ro2(const void *refcount_array, uint64_t index); 42 static uint64_t get_refcount_ro3(const void *refcount_array, uint64_t index); 43 static uint64_t get_refcount_ro4(const void *refcount_array, uint64_t index); 44 static uint64_t get_refcount_ro5(const void *refcount_array, uint64_t index); 45 static uint64_t get_refcount_ro6(const void *refcount_array, uint64_t index); 46 47 static void set_refcount_ro0(void *refcount_array, uint64_t index, 48 uint64_t value); 49 static void set_refcount_ro1(void *refcount_array, uint64_t index, 50 uint64_t value); 51 static void set_refcount_ro2(void *refcount_array, uint64_t index, 52 uint64_t value); 53 static void set_refcount_ro3(void *refcount_array, uint64_t index, 54 uint64_t value); 55 static void set_refcount_ro4(void *refcount_array, uint64_t index, 56 uint64_t value); 57 static void set_refcount_ro5(void *refcount_array, uint64_t index, 58 uint64_t value); 59 static void set_refcount_ro6(void *refcount_array, uint64_t index, 60 uint64_t value); 61 62 63 static Qcow2GetRefcountFunc *const get_refcount_funcs[] = { 64 &get_refcount_ro0, 65 &get_refcount_ro1, 66 &get_refcount_ro2, 67 &get_refcount_ro3, 68 &get_refcount_ro4, 69 &get_refcount_ro5, 70 &get_refcount_ro6 71 }; 72 73 static Qcow2SetRefcountFunc *const set_refcount_funcs[] = { 74 &set_refcount_ro0, 75 &set_refcount_ro1, 76 &set_refcount_ro2, 77 &set_refcount_ro3, 78 &set_refcount_ro4, 79 &set_refcount_ro5, 80 &set_refcount_ro6 81 }; 82 83 84 /*********************************************************/ 85 /* refcount handling */ 86 87 static void update_max_refcount_table_index(BDRVQcow2State *s) 88 { 89 unsigned i = s->refcount_table_size - 1; 90 while (i > 0 && (s->refcount_table[i] & REFT_OFFSET_MASK) == 0) { 91 i--; 92 } 93 /* Set s->max_refcount_table_index to the index of the last used entry */ 94 s->max_refcount_table_index = i; 95 } 96 97 int qcow2_refcount_init(BlockDriverState *bs) 98 { 99 BDRVQcow2State *s = bs->opaque; 100 unsigned int refcount_table_size2, i; 101 int ret; 102 103 assert(s->refcount_order >= 0 && s->refcount_order <= 6); 104 105 s->get_refcount = get_refcount_funcs[s->refcount_order]; 106 s->set_refcount = set_refcount_funcs[s->refcount_order]; 107 108 assert(s->refcount_table_size <= INT_MAX / sizeof(uint64_t)); 109 refcount_table_size2 = s->refcount_table_size * sizeof(uint64_t); 110 s->refcount_table = g_try_malloc(refcount_table_size2); 111 112 if (s->refcount_table_size > 0) { 113 if (s->refcount_table == NULL) { 114 ret = -ENOMEM; 115 goto fail; 116 } 117 BLKDBG_EVENT(bs->file, BLKDBG_REFTABLE_LOAD); 118 ret = bdrv_pread(bs->file, s->refcount_table_offset, 119 s->refcount_table, refcount_table_size2); 120 if (ret < 0) { 121 goto fail; 122 } 123 for(i = 0; i < s->refcount_table_size; i++) 124 be64_to_cpus(&s->refcount_table[i]); 125 update_max_refcount_table_index(s); 126 } 127 return 0; 128 fail: 129 return ret; 130 } 131 132 void qcow2_refcount_close(BlockDriverState *bs) 133 { 134 BDRVQcow2State *s = bs->opaque; 135 g_free(s->refcount_table); 136 } 137 138 139 static uint64_t get_refcount_ro0(const void *refcount_array, uint64_t index) 140 { 141 return (((const uint8_t *)refcount_array)[index / 8] >> (index % 8)) & 0x1; 142 } 143 144 static void set_refcount_ro0(void *refcount_array, uint64_t index, 145 uint64_t value) 146 { 147 assert(!(value >> 1)); 148 ((uint8_t *)refcount_array)[index / 8] &= ~(0x1 << (index % 8)); 149 ((uint8_t *)refcount_array)[index / 8] |= value << (index % 8); 150 } 151 152 static uint64_t get_refcount_ro1(const void *refcount_array, uint64_t index) 153 { 154 return (((const uint8_t *)refcount_array)[index / 4] >> (2 * (index % 4))) 155 & 0x3; 156 } 157 158 static void set_refcount_ro1(void *refcount_array, uint64_t index, 159 uint64_t value) 160 { 161 assert(!(value >> 2)); 162 ((uint8_t *)refcount_array)[index / 4] &= ~(0x3 << (2 * (index % 4))); 163 ((uint8_t *)refcount_array)[index / 4] |= value << (2 * (index % 4)); 164 } 165 166 static uint64_t get_refcount_ro2(const void *refcount_array, uint64_t index) 167 { 168 return (((const uint8_t *)refcount_array)[index / 2] >> (4 * (index % 2))) 169 & 0xf; 170 } 171 172 static void set_refcount_ro2(void *refcount_array, uint64_t index, 173 uint64_t value) 174 { 175 assert(!(value >> 4)); 176 ((uint8_t *)refcount_array)[index / 2] &= ~(0xf << (4 * (index % 2))); 177 ((uint8_t *)refcount_array)[index / 2] |= value << (4 * (index % 2)); 178 } 179 180 static uint64_t get_refcount_ro3(const void *refcount_array, uint64_t index) 181 { 182 return ((const uint8_t *)refcount_array)[index]; 183 } 184 185 static void set_refcount_ro3(void *refcount_array, uint64_t index, 186 uint64_t value) 187 { 188 assert(!(value >> 8)); 189 ((uint8_t *)refcount_array)[index] = value; 190 } 191 192 static uint64_t get_refcount_ro4(const void *refcount_array, uint64_t index) 193 { 194 return be16_to_cpu(((const uint16_t *)refcount_array)[index]); 195 } 196 197 static void set_refcount_ro4(void *refcount_array, uint64_t index, 198 uint64_t value) 199 { 200 assert(!(value >> 16)); 201 ((uint16_t *)refcount_array)[index] = cpu_to_be16(value); 202 } 203 204 static uint64_t get_refcount_ro5(const void *refcount_array, uint64_t index) 205 { 206 return be32_to_cpu(((const uint32_t *)refcount_array)[index]); 207 } 208 209 static void set_refcount_ro5(void *refcount_array, uint64_t index, 210 uint64_t value) 211 { 212 assert(!(value >> 32)); 213 ((uint32_t *)refcount_array)[index] = cpu_to_be32(value); 214 } 215 216 static uint64_t get_refcount_ro6(const void *refcount_array, uint64_t index) 217 { 218 return be64_to_cpu(((const uint64_t *)refcount_array)[index]); 219 } 220 221 static void set_refcount_ro6(void *refcount_array, uint64_t index, 222 uint64_t value) 223 { 224 ((uint64_t *)refcount_array)[index] = cpu_to_be64(value); 225 } 226 227 228 static int load_refcount_block(BlockDriverState *bs, 229 int64_t refcount_block_offset, 230 void **refcount_block) 231 { 232 BDRVQcow2State *s = bs->opaque; 233 234 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_LOAD); 235 return qcow2_cache_get(bs, s->refcount_block_cache, refcount_block_offset, 236 refcount_block); 237 } 238 239 /* 240 * Retrieves the refcount of the cluster given by its index and stores it in 241 * *refcount. Returns 0 on success and -errno on failure. 242 */ 243 int qcow2_get_refcount(BlockDriverState *bs, int64_t cluster_index, 244 uint64_t *refcount) 245 { 246 BDRVQcow2State *s = bs->opaque; 247 uint64_t refcount_table_index, block_index; 248 int64_t refcount_block_offset; 249 int ret; 250 void *refcount_block; 251 252 refcount_table_index = cluster_index >> s->refcount_block_bits; 253 if (refcount_table_index >= s->refcount_table_size) { 254 *refcount = 0; 255 return 0; 256 } 257 refcount_block_offset = 258 s->refcount_table[refcount_table_index] & REFT_OFFSET_MASK; 259 if (!refcount_block_offset) { 260 *refcount = 0; 261 return 0; 262 } 263 264 if (offset_into_cluster(s, refcount_block_offset)) { 265 qcow2_signal_corruption(bs, true, -1, -1, "Refblock offset %#" PRIx64 266 " unaligned (reftable index: %#" PRIx64 ")", 267 refcount_block_offset, refcount_table_index); 268 return -EIO; 269 } 270 271 ret = qcow2_cache_get(bs, s->refcount_block_cache, refcount_block_offset, 272 &refcount_block); 273 if (ret < 0) { 274 return ret; 275 } 276 277 block_index = cluster_index & (s->refcount_block_size - 1); 278 *refcount = s->get_refcount(refcount_block, block_index); 279 280 qcow2_cache_put(s->refcount_block_cache, &refcount_block); 281 282 return 0; 283 } 284 285 /* Checks if two offsets are described by the same refcount block */ 286 static int in_same_refcount_block(BDRVQcow2State *s, uint64_t offset_a, 287 uint64_t offset_b) 288 { 289 uint64_t block_a = offset_a >> (s->cluster_bits + s->refcount_block_bits); 290 uint64_t block_b = offset_b >> (s->cluster_bits + s->refcount_block_bits); 291 292 return (block_a == block_b); 293 } 294 295 /* 296 * Loads a refcount block. If it doesn't exist yet, it is allocated first 297 * (including growing the refcount table if needed). 298 * 299 * Returns 0 on success or -errno in error case 300 */ 301 static int alloc_refcount_block(BlockDriverState *bs, 302 int64_t cluster_index, void **refcount_block) 303 { 304 BDRVQcow2State *s = bs->opaque; 305 unsigned int refcount_table_index; 306 int64_t ret; 307 308 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC); 309 310 /* Find the refcount block for the given cluster */ 311 refcount_table_index = cluster_index >> s->refcount_block_bits; 312 313 if (refcount_table_index < s->refcount_table_size) { 314 315 uint64_t refcount_block_offset = 316 s->refcount_table[refcount_table_index] & REFT_OFFSET_MASK; 317 318 /* If it's already there, we're done */ 319 if (refcount_block_offset) { 320 if (offset_into_cluster(s, refcount_block_offset)) { 321 qcow2_signal_corruption(bs, true, -1, -1, "Refblock offset %#" 322 PRIx64 " unaligned (reftable index: " 323 "%#x)", refcount_block_offset, 324 refcount_table_index); 325 return -EIO; 326 } 327 328 return load_refcount_block(bs, refcount_block_offset, 329 refcount_block); 330 } 331 } 332 333 /* 334 * If we came here, we need to allocate something. Something is at least 335 * a cluster for the new refcount block. It may also include a new refcount 336 * table if the old refcount table is too small. 337 * 338 * Note that allocating clusters here needs some special care: 339 * 340 * - We can't use the normal qcow2_alloc_clusters(), it would try to 341 * increase the refcount and very likely we would end up with an endless 342 * recursion. Instead we must place the refcount blocks in a way that 343 * they can describe them themselves. 344 * 345 * - We need to consider that at this point we are inside update_refcounts 346 * and potentially doing an initial refcount increase. This means that 347 * some clusters have already been allocated by the caller, but their 348 * refcount isn't accurate yet. If we allocate clusters for metadata, we 349 * need to return -EAGAIN to signal the caller that it needs to restart 350 * the search for free clusters. 351 * 352 * - alloc_clusters_noref and qcow2_free_clusters may load a different 353 * refcount block into the cache 354 */ 355 356 *refcount_block = NULL; 357 358 /* We write to the refcount table, so we might depend on L2 tables */ 359 ret = qcow2_cache_flush(bs, s->l2_table_cache); 360 if (ret < 0) { 361 return ret; 362 } 363 364 /* Allocate the refcount block itself and mark it as used */ 365 int64_t new_block = alloc_clusters_noref(bs, s->cluster_size, INT64_MAX); 366 if (new_block < 0) { 367 return new_block; 368 } 369 370 /* The offset must fit in the offset field of the refcount table entry */ 371 assert((new_block & REFT_OFFSET_MASK) == new_block); 372 373 /* If we're allocating the block at offset 0 then something is wrong */ 374 if (new_block == 0) { 375 qcow2_signal_corruption(bs, true, -1, -1, "Preventing invalid " 376 "allocation of refcount block at offset 0"); 377 return -EIO; 378 } 379 380 #ifdef DEBUG_ALLOC2 381 fprintf(stderr, "qcow2: Allocate refcount block %d for %" PRIx64 382 " at %" PRIx64 "\n", 383 refcount_table_index, cluster_index << s->cluster_bits, new_block); 384 #endif 385 386 if (in_same_refcount_block(s, new_block, cluster_index << s->cluster_bits)) { 387 /* Zero the new refcount block before updating it */ 388 ret = qcow2_cache_get_empty(bs, s->refcount_block_cache, new_block, 389 refcount_block); 390 if (ret < 0) { 391 goto fail; 392 } 393 394 memset(*refcount_block, 0, s->cluster_size); 395 396 /* The block describes itself, need to update the cache */ 397 int block_index = (new_block >> s->cluster_bits) & 398 (s->refcount_block_size - 1); 399 s->set_refcount(*refcount_block, block_index, 1); 400 } else { 401 /* Described somewhere else. This can recurse at most twice before we 402 * arrive at a block that describes itself. */ 403 ret = update_refcount(bs, new_block, s->cluster_size, 1, false, 404 QCOW2_DISCARD_NEVER); 405 if (ret < 0) { 406 goto fail; 407 } 408 409 ret = qcow2_cache_flush(bs, s->refcount_block_cache); 410 if (ret < 0) { 411 goto fail; 412 } 413 414 /* Initialize the new refcount block only after updating its refcount, 415 * update_refcount uses the refcount cache itself */ 416 ret = qcow2_cache_get_empty(bs, s->refcount_block_cache, new_block, 417 refcount_block); 418 if (ret < 0) { 419 goto fail; 420 } 421 422 memset(*refcount_block, 0, s->cluster_size); 423 } 424 425 /* Now the new refcount block needs to be written to disk */ 426 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_WRITE); 427 qcow2_cache_entry_mark_dirty(s->refcount_block_cache, *refcount_block); 428 ret = qcow2_cache_flush(bs, s->refcount_block_cache); 429 if (ret < 0) { 430 goto fail; 431 } 432 433 /* If the refcount table is big enough, just hook the block up there */ 434 if (refcount_table_index < s->refcount_table_size) { 435 uint64_t data64 = cpu_to_be64(new_block); 436 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_HOOKUP); 437 ret = bdrv_pwrite_sync(bs->file, 438 s->refcount_table_offset + refcount_table_index * sizeof(uint64_t), 439 &data64, sizeof(data64)); 440 if (ret < 0) { 441 goto fail; 442 } 443 444 s->refcount_table[refcount_table_index] = new_block; 445 /* If there's a hole in s->refcount_table then it can happen 446 * that refcount_table_index < s->max_refcount_table_index */ 447 s->max_refcount_table_index = 448 MAX(s->max_refcount_table_index, refcount_table_index); 449 450 /* The new refcount block may be where the caller intended to put its 451 * data, so let it restart the search. */ 452 return -EAGAIN; 453 } 454 455 qcow2_cache_put(s->refcount_block_cache, refcount_block); 456 457 /* 458 * If we come here, we need to grow the refcount table. Again, a new 459 * refcount table needs some space and we can't simply allocate to avoid 460 * endless recursion. 461 * 462 * Therefore let's grab new refcount blocks at the end of the image, which 463 * will describe themselves and the new refcount table. This way we can 464 * reference them only in the new table and do the switch to the new 465 * refcount table at once without producing an inconsistent state in 466 * between. 467 */ 468 BLKDBG_EVENT(bs->file, BLKDBG_REFTABLE_GROW); 469 470 /* Calculate the number of refcount blocks needed so far; this will be the 471 * basis for calculating the index of the first cluster used for the 472 * self-describing refcount structures which we are about to create. 473 * 474 * Because we reached this point, there cannot be any refcount entries for 475 * cluster_index or higher indices yet. However, because new_block has been 476 * allocated to describe that cluster (and it will assume this role later 477 * on), we cannot use that index; also, new_block may actually have a higher 478 * cluster index than cluster_index, so it needs to be taken into account 479 * here (and 1 needs to be added to its value because that cluster is used). 480 */ 481 uint64_t blocks_used = DIV_ROUND_UP(MAX(cluster_index + 1, 482 (new_block >> s->cluster_bits) + 1), 483 s->refcount_block_size); 484 485 /* Create the new refcount table and blocks */ 486 uint64_t meta_offset = (blocks_used * s->refcount_block_size) * 487 s->cluster_size; 488 489 ret = qcow2_refcount_area(bs, meta_offset, 0, false, 490 refcount_table_index, new_block); 491 if (ret < 0) { 492 return ret; 493 } 494 495 ret = load_refcount_block(bs, new_block, refcount_block); 496 if (ret < 0) { 497 return ret; 498 } 499 500 /* If we were trying to do the initial refcount update for some cluster 501 * allocation, we might have used the same clusters to store newly 502 * allocated metadata. Make the caller search some new space. */ 503 return -EAGAIN; 504 505 fail: 506 if (*refcount_block != NULL) { 507 qcow2_cache_put(s->refcount_block_cache, refcount_block); 508 } 509 return ret; 510 } 511 512 /* 513 * Starting at @start_offset, this function creates new self-covering refcount 514 * structures: A new refcount table and refcount blocks which cover all of 515 * themselves, and a number of @additional_clusters beyond their end. 516 * @start_offset must be at the end of the image file, that is, there must be 517 * only empty space beyond it. 518 * If @exact_size is false, the refcount table will have 50 % more entries than 519 * necessary so it will not need to grow again soon. 520 * If @new_refblock_offset is not zero, it contains the offset of a refcount 521 * block that should be entered into the new refcount table at index 522 * @new_refblock_index. 523 * 524 * Returns: The offset after the new refcount structures (i.e. where the 525 * @additional_clusters may be placed) on success, -errno on error. 526 */ 527 int64_t qcow2_refcount_area(BlockDriverState *bs, uint64_t start_offset, 528 uint64_t additional_clusters, bool exact_size, 529 int new_refblock_index, 530 uint64_t new_refblock_offset) 531 { 532 BDRVQcow2State *s = bs->opaque; 533 uint64_t total_refblock_count_u64, additional_refblock_count; 534 int total_refblock_count, table_size, area_reftable_index, table_clusters; 535 int i; 536 uint64_t table_offset, block_offset, end_offset; 537 int ret; 538 uint64_t *new_table; 539 540 assert(!(start_offset % s->cluster_size)); 541 542 qcow2_refcount_metadata_size(start_offset / s->cluster_size + 543 additional_clusters, 544 s->cluster_size, s->refcount_order, 545 !exact_size, &total_refblock_count_u64); 546 if (total_refblock_count_u64 > QCOW_MAX_REFTABLE_SIZE) { 547 return -EFBIG; 548 } 549 total_refblock_count = total_refblock_count_u64; 550 551 /* Index in the refcount table of the first refcount block to cover the area 552 * of refcount structures we are about to create; we know that 553 * @total_refblock_count can cover @start_offset, so this will definitely 554 * fit into an int. */ 555 area_reftable_index = (start_offset / s->cluster_size) / 556 s->refcount_block_size; 557 558 if (exact_size) { 559 table_size = total_refblock_count; 560 } else { 561 table_size = total_refblock_count + 562 DIV_ROUND_UP(total_refblock_count, 2); 563 } 564 /* The qcow2 file can only store the reftable size in number of clusters */ 565 table_size = ROUND_UP(table_size, s->cluster_size / sizeof(uint64_t)); 566 table_clusters = (table_size * sizeof(uint64_t)) / s->cluster_size; 567 568 if (table_size > QCOW_MAX_REFTABLE_SIZE) { 569 return -EFBIG; 570 } 571 572 new_table = g_try_new0(uint64_t, table_size); 573 574 assert(table_size > 0); 575 if (new_table == NULL) { 576 ret = -ENOMEM; 577 goto fail; 578 } 579 580 /* Fill the new refcount table */ 581 if (table_size > s->max_refcount_table_index) { 582 /* We're actually growing the reftable */ 583 memcpy(new_table, s->refcount_table, 584 (s->max_refcount_table_index + 1) * sizeof(uint64_t)); 585 } else { 586 /* Improbable case: We're shrinking the reftable. However, the caller 587 * has assured us that there is only empty space beyond @start_offset, 588 * so we can simply drop all of the refblocks that won't fit into the 589 * new reftable. */ 590 memcpy(new_table, s->refcount_table, table_size * sizeof(uint64_t)); 591 } 592 593 if (new_refblock_offset) { 594 assert(new_refblock_index < total_refblock_count); 595 new_table[new_refblock_index] = new_refblock_offset; 596 } 597 598 /* Count how many new refblocks we have to create */ 599 additional_refblock_count = 0; 600 for (i = area_reftable_index; i < total_refblock_count; i++) { 601 if (!new_table[i]) { 602 additional_refblock_count++; 603 } 604 } 605 606 table_offset = start_offset + additional_refblock_count * s->cluster_size; 607 end_offset = table_offset + table_clusters * s->cluster_size; 608 609 /* Fill the refcount blocks, and create new ones, if necessary */ 610 block_offset = start_offset; 611 for (i = area_reftable_index; i < total_refblock_count; i++) { 612 void *refblock_data; 613 uint64_t first_offset_covered; 614 615 /* Reuse an existing refblock if possible, create a new one otherwise */ 616 if (new_table[i]) { 617 ret = qcow2_cache_get(bs, s->refcount_block_cache, new_table[i], 618 &refblock_data); 619 if (ret < 0) { 620 goto fail; 621 } 622 } else { 623 ret = qcow2_cache_get_empty(bs, s->refcount_block_cache, 624 block_offset, &refblock_data); 625 if (ret < 0) { 626 goto fail; 627 } 628 memset(refblock_data, 0, s->cluster_size); 629 qcow2_cache_entry_mark_dirty(s->refcount_block_cache, 630 refblock_data); 631 632 new_table[i] = block_offset; 633 block_offset += s->cluster_size; 634 } 635 636 /* First host offset covered by this refblock */ 637 first_offset_covered = (uint64_t)i * s->refcount_block_size * 638 s->cluster_size; 639 if (first_offset_covered < end_offset) { 640 int j, end_index; 641 642 /* Set the refcount of all of the new refcount structures to 1 */ 643 644 if (first_offset_covered < start_offset) { 645 assert(i == area_reftable_index); 646 j = (start_offset - first_offset_covered) / s->cluster_size; 647 assert(j < s->refcount_block_size); 648 } else { 649 j = 0; 650 } 651 652 end_index = MIN((end_offset - first_offset_covered) / 653 s->cluster_size, 654 s->refcount_block_size); 655 656 for (; j < end_index; j++) { 657 /* The caller guaranteed us this space would be empty */ 658 assert(s->get_refcount(refblock_data, j) == 0); 659 s->set_refcount(refblock_data, j, 1); 660 } 661 662 qcow2_cache_entry_mark_dirty(s->refcount_block_cache, 663 refblock_data); 664 } 665 666 qcow2_cache_put(s->refcount_block_cache, &refblock_data); 667 } 668 669 assert(block_offset == table_offset); 670 671 /* Write refcount blocks to disk */ 672 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_WRITE_BLOCKS); 673 ret = qcow2_cache_flush(bs, s->refcount_block_cache); 674 if (ret < 0) { 675 goto fail; 676 } 677 678 /* Write refcount table to disk */ 679 for (i = 0; i < total_refblock_count; i++) { 680 cpu_to_be64s(&new_table[i]); 681 } 682 683 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_WRITE_TABLE); 684 ret = bdrv_pwrite_sync(bs->file, table_offset, new_table, 685 table_size * sizeof(uint64_t)); 686 if (ret < 0) { 687 goto fail; 688 } 689 690 for (i = 0; i < total_refblock_count; i++) { 691 be64_to_cpus(&new_table[i]); 692 } 693 694 /* Hook up the new refcount table in the qcow2 header */ 695 struct QEMU_PACKED { 696 uint64_t d64; 697 uint32_t d32; 698 } data; 699 data.d64 = cpu_to_be64(table_offset); 700 data.d32 = cpu_to_be32(table_clusters); 701 BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_SWITCH_TABLE); 702 ret = bdrv_pwrite_sync(bs->file, 703 offsetof(QCowHeader, refcount_table_offset), 704 &data, sizeof(data)); 705 if (ret < 0) { 706 goto fail; 707 } 708 709 /* And switch it in memory */ 710 uint64_t old_table_offset = s->refcount_table_offset; 711 uint64_t old_table_size = s->refcount_table_size; 712 713 g_free(s->refcount_table); 714 s->refcount_table = new_table; 715 s->refcount_table_size = table_size; 716 s->refcount_table_offset = table_offset; 717 update_max_refcount_table_index(s); 718 719 /* Free old table. */ 720 qcow2_free_clusters(bs, old_table_offset, old_table_size * sizeof(uint64_t), 721 QCOW2_DISCARD_OTHER); 722 723 return end_offset; 724 725 fail: 726 g_free(new_table); 727 return ret; 728 } 729 730 void qcow2_process_discards(BlockDriverState *bs, int ret) 731 { 732 BDRVQcow2State *s = bs->opaque; 733 Qcow2DiscardRegion *d, *next; 734 735 QTAILQ_FOREACH_SAFE(d, &s->discards, next, next) { 736 QTAILQ_REMOVE(&s->discards, d, next); 737 738 /* Discard is optional, ignore the return value */ 739 if (ret >= 0) { 740 int r2 = bdrv_pdiscard(bs->file, d->offset, d->bytes); 741 if (r2 < 0) { 742 trace_qcow2_process_discards_failed_region(d->offset, d->bytes, 743 r2); 744 } 745 } 746 747 g_free(d); 748 } 749 } 750 751 static void update_refcount_discard(BlockDriverState *bs, 752 uint64_t offset, uint64_t length) 753 { 754 BDRVQcow2State *s = bs->opaque; 755 Qcow2DiscardRegion *d, *p, *next; 756 757 QTAILQ_FOREACH(d, &s->discards, next) { 758 uint64_t new_start = MIN(offset, d->offset); 759 uint64_t new_end = MAX(offset + length, d->offset + d->bytes); 760 761 if (new_end - new_start <= length + d->bytes) { 762 /* There can't be any overlap, areas ending up here have no 763 * references any more and therefore shouldn't get freed another 764 * time. */ 765 assert(d->bytes + length == new_end - new_start); 766 d->offset = new_start; 767 d->bytes = new_end - new_start; 768 goto found; 769 } 770 } 771 772 d = g_malloc(sizeof(*d)); 773 *d = (Qcow2DiscardRegion) { 774 .bs = bs, 775 .offset = offset, 776 .bytes = length, 777 }; 778 QTAILQ_INSERT_TAIL(&s->discards, d, next); 779 780 found: 781 /* Merge discard requests if they are adjacent now */ 782 QTAILQ_FOREACH_SAFE(p, &s->discards, next, next) { 783 if (p == d 784 || p->offset > d->offset + d->bytes 785 || d->offset > p->offset + p->bytes) 786 { 787 continue; 788 } 789 790 /* Still no overlap possible */ 791 assert(p->offset == d->offset + d->bytes 792 || d->offset == p->offset + p->bytes); 793 794 QTAILQ_REMOVE(&s->discards, p, next); 795 d->offset = MIN(d->offset, p->offset); 796 d->bytes += p->bytes; 797 g_free(p); 798 } 799 } 800 801 /* XXX: cache several refcount block clusters ? */ 802 /* @addend is the absolute value of the addend; if @decrease is set, @addend 803 * will be subtracted from the current refcount, otherwise it will be added */ 804 static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs, 805 int64_t offset, 806 int64_t length, 807 uint64_t addend, 808 bool decrease, 809 enum qcow2_discard_type type) 810 { 811 BDRVQcow2State *s = bs->opaque; 812 int64_t start, last, cluster_offset; 813 void *refcount_block = NULL; 814 int64_t old_table_index = -1; 815 int ret; 816 817 #ifdef DEBUG_ALLOC2 818 fprintf(stderr, "update_refcount: offset=%" PRId64 " size=%" PRId64 819 " addend=%s%" PRIu64 "\n", offset, length, decrease ? "-" : "", 820 addend); 821 #endif 822 if (length < 0) { 823 return -EINVAL; 824 } else if (length == 0) { 825 return 0; 826 } 827 828 if (decrease) { 829 qcow2_cache_set_dependency(bs, s->refcount_block_cache, 830 s->l2_table_cache); 831 } 832 833 start = start_of_cluster(s, offset); 834 last = start_of_cluster(s, offset + length - 1); 835 for(cluster_offset = start; cluster_offset <= last; 836 cluster_offset += s->cluster_size) 837 { 838 int block_index; 839 uint64_t refcount; 840 int64_t cluster_index = cluster_offset >> s->cluster_bits; 841 int64_t table_index = cluster_index >> s->refcount_block_bits; 842 843 /* Load the refcount block and allocate it if needed */ 844 if (table_index != old_table_index) { 845 if (refcount_block) { 846 qcow2_cache_put(s->refcount_block_cache, &refcount_block); 847 } 848 ret = alloc_refcount_block(bs, cluster_index, &refcount_block); 849 /* If the caller needs to restart the search for free clusters, 850 * try the same ones first to see if they're still free. */ 851 if (ret == -EAGAIN) { 852 if (s->free_cluster_index > (start >> s->cluster_bits)) { 853 s->free_cluster_index = (start >> s->cluster_bits); 854 } 855 } 856 if (ret < 0) { 857 goto fail; 858 } 859 } 860 old_table_index = table_index; 861 862 qcow2_cache_entry_mark_dirty(s->refcount_block_cache, refcount_block); 863 864 /* we can update the count and save it */ 865 block_index = cluster_index & (s->refcount_block_size - 1); 866 867 refcount = s->get_refcount(refcount_block, block_index); 868 if (decrease ? (refcount - addend > refcount) 869 : (refcount + addend < refcount || 870 refcount + addend > s->refcount_max)) 871 { 872 ret = -EINVAL; 873 goto fail; 874 } 875 if (decrease) { 876 refcount -= addend; 877 } else { 878 refcount += addend; 879 } 880 if (refcount == 0 && cluster_index < s->free_cluster_index) { 881 s->free_cluster_index = cluster_index; 882 } 883 s->set_refcount(refcount_block, block_index, refcount); 884 885 if (refcount == 0) { 886 void *table; 887 888 table = qcow2_cache_is_table_offset(s->refcount_block_cache, 889 offset); 890 if (table != NULL) { 891 qcow2_cache_put(s->refcount_block_cache, &refcount_block); 892 qcow2_cache_discard(s->refcount_block_cache, table); 893 } 894 895 table = qcow2_cache_is_table_offset(s->l2_table_cache, offset); 896 if (table != NULL) { 897 qcow2_cache_discard(s->l2_table_cache, table); 898 } 899 900 if (s->discard_passthrough[type]) { 901 update_refcount_discard(bs, cluster_offset, s->cluster_size); 902 } 903 } 904 } 905 906 ret = 0; 907 fail: 908 if (!s->cache_discards) { 909 qcow2_process_discards(bs, ret); 910 } 911 912 /* Write last changed block to disk */ 913 if (refcount_block) { 914 qcow2_cache_put(s->refcount_block_cache, &refcount_block); 915 } 916 917 /* 918 * Try do undo any updates if an error is returned (This may succeed in 919 * some cases like ENOSPC for allocating a new refcount block) 920 */ 921 if (ret < 0) { 922 int dummy; 923 dummy = update_refcount(bs, offset, cluster_offset - offset, addend, 924 !decrease, QCOW2_DISCARD_NEVER); 925 (void)dummy; 926 } 927 928 return ret; 929 } 930 931 /* 932 * Increases or decreases the refcount of a given cluster. 933 * 934 * @addend is the absolute value of the addend; if @decrease is set, @addend 935 * will be subtracted from the current refcount, otherwise it will be added. 936 * 937 * On success 0 is returned; on failure -errno is returned. 938 */ 939 int qcow2_update_cluster_refcount(BlockDriverState *bs, 940 int64_t cluster_index, 941 uint64_t addend, bool decrease, 942 enum qcow2_discard_type type) 943 { 944 BDRVQcow2State *s = bs->opaque; 945 int ret; 946 947 ret = update_refcount(bs, cluster_index << s->cluster_bits, 1, addend, 948 decrease, type); 949 if (ret < 0) { 950 return ret; 951 } 952 953 return 0; 954 } 955 956 957 958 /*********************************************************/ 959 /* cluster allocation functions */ 960 961 962 963 /* return < 0 if error */ 964 static int64_t alloc_clusters_noref(BlockDriverState *bs, uint64_t size, 965 uint64_t max) 966 { 967 BDRVQcow2State *s = bs->opaque; 968 uint64_t i, nb_clusters, refcount; 969 int ret; 970 971 /* We can't allocate clusters if they may still be queued for discard. */ 972 if (s->cache_discards) { 973 qcow2_process_discards(bs, 0); 974 } 975 976 nb_clusters = size_to_clusters(s, size); 977 retry: 978 for(i = 0; i < nb_clusters; i++) { 979 uint64_t next_cluster_index = s->free_cluster_index++; 980 ret = qcow2_get_refcount(bs, next_cluster_index, &refcount); 981 982 if (ret < 0) { 983 return ret; 984 } else if (refcount != 0) { 985 goto retry; 986 } 987 } 988 989 /* Make sure that all offsets in the "allocated" range are representable 990 * in the requested max */ 991 if (s->free_cluster_index > 0 && 992 s->free_cluster_index - 1 > (max >> s->cluster_bits)) 993 { 994 return -EFBIG; 995 } 996 997 #ifdef DEBUG_ALLOC2 998 fprintf(stderr, "alloc_clusters: size=%" PRId64 " -> %" PRId64 "\n", 999 size, 1000 (s->free_cluster_index - nb_clusters) << s->cluster_bits); 1001 #endif 1002 return (s->free_cluster_index - nb_clusters) << s->cluster_bits; 1003 } 1004 1005 int64_t qcow2_alloc_clusters(BlockDriverState *bs, uint64_t size) 1006 { 1007 int64_t offset; 1008 int ret; 1009 1010 BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_ALLOC); 1011 do { 1012 offset = alloc_clusters_noref(bs, size, QCOW_MAX_CLUSTER_OFFSET); 1013 if (offset < 0) { 1014 return offset; 1015 } 1016 1017 ret = update_refcount(bs, offset, size, 1, false, QCOW2_DISCARD_NEVER); 1018 } while (ret == -EAGAIN); 1019 1020 if (ret < 0) { 1021 return ret; 1022 } 1023 1024 return offset; 1025 } 1026 1027 int64_t qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t offset, 1028 int64_t nb_clusters) 1029 { 1030 BDRVQcow2State *s = bs->opaque; 1031 uint64_t cluster_index, refcount; 1032 uint64_t i; 1033 int ret; 1034 1035 assert(nb_clusters >= 0); 1036 if (nb_clusters == 0) { 1037 return 0; 1038 } 1039 1040 do { 1041 /* Check how many clusters there are free */ 1042 cluster_index = offset >> s->cluster_bits; 1043 for(i = 0; i < nb_clusters; i++) { 1044 ret = qcow2_get_refcount(bs, cluster_index++, &refcount); 1045 if (ret < 0) { 1046 return ret; 1047 } else if (refcount != 0) { 1048 break; 1049 } 1050 } 1051 1052 /* And then allocate them */ 1053 ret = update_refcount(bs, offset, i << s->cluster_bits, 1, false, 1054 QCOW2_DISCARD_NEVER); 1055 } while (ret == -EAGAIN); 1056 1057 if (ret < 0) { 1058 return ret; 1059 } 1060 1061 return i; 1062 } 1063 1064 /* only used to allocate compressed sectors. We try to allocate 1065 contiguous sectors. size must be <= cluster_size */ 1066 int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size) 1067 { 1068 BDRVQcow2State *s = bs->opaque; 1069 int64_t offset; 1070 size_t free_in_cluster; 1071 int ret; 1072 1073 BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_ALLOC_BYTES); 1074 assert(size > 0 && size <= s->cluster_size); 1075 assert(!s->free_byte_offset || offset_into_cluster(s, s->free_byte_offset)); 1076 1077 offset = s->free_byte_offset; 1078 1079 if (offset) { 1080 uint64_t refcount; 1081 ret = qcow2_get_refcount(bs, offset >> s->cluster_bits, &refcount); 1082 if (ret < 0) { 1083 return ret; 1084 } 1085 1086 if (refcount == s->refcount_max) { 1087 offset = 0; 1088 } 1089 } 1090 1091 free_in_cluster = s->cluster_size - offset_into_cluster(s, offset); 1092 do { 1093 if (!offset || free_in_cluster < size) { 1094 int64_t new_cluster; 1095 1096 new_cluster = alloc_clusters_noref(bs, s->cluster_size, 1097 MIN(s->cluster_offset_mask, 1098 QCOW_MAX_CLUSTER_OFFSET)); 1099 if (new_cluster < 0) { 1100 return new_cluster; 1101 } 1102 1103 if (new_cluster == 0) { 1104 qcow2_signal_corruption(bs, true, -1, -1, "Preventing invalid " 1105 "allocation of compressed cluster " 1106 "at offset 0"); 1107 return -EIO; 1108 } 1109 1110 if (!offset || ROUND_UP(offset, s->cluster_size) != new_cluster) { 1111 offset = new_cluster; 1112 free_in_cluster = s->cluster_size; 1113 } else { 1114 free_in_cluster += s->cluster_size; 1115 } 1116 } 1117 1118 assert(offset); 1119 ret = update_refcount(bs, offset, size, 1, false, QCOW2_DISCARD_NEVER); 1120 if (ret < 0) { 1121 offset = 0; 1122 } 1123 } while (ret == -EAGAIN); 1124 if (ret < 0) { 1125 return ret; 1126 } 1127 1128 /* The cluster refcount was incremented; refcount blocks must be flushed 1129 * before the caller's L2 table updates. */ 1130 qcow2_cache_set_dependency(bs, s->l2_table_cache, s->refcount_block_cache); 1131 1132 s->free_byte_offset = offset + size; 1133 if (!offset_into_cluster(s, s->free_byte_offset)) { 1134 s->free_byte_offset = 0; 1135 } 1136 1137 return offset; 1138 } 1139 1140 void qcow2_free_clusters(BlockDriverState *bs, 1141 int64_t offset, int64_t size, 1142 enum qcow2_discard_type type) 1143 { 1144 int ret; 1145 1146 BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_FREE); 1147 ret = update_refcount(bs, offset, size, 1, true, type); 1148 if (ret < 0) { 1149 fprintf(stderr, "qcow2_free_clusters failed: %s\n", strerror(-ret)); 1150 /* TODO Remember the clusters to free them later and avoid leaking */ 1151 } 1152 } 1153 1154 /* 1155 * Free a cluster using its L2 entry (handles clusters of all types, e.g. 1156 * normal cluster, compressed cluster, etc.) 1157 */ 1158 void qcow2_free_any_clusters(BlockDriverState *bs, uint64_t l2_entry, 1159 int nb_clusters, enum qcow2_discard_type type) 1160 { 1161 BDRVQcow2State *s = bs->opaque; 1162 QCow2ClusterType ctype = qcow2_get_cluster_type(bs, l2_entry); 1163 1164 if (has_data_file(bs)) { 1165 if (s->discard_passthrough[type] && 1166 (ctype == QCOW2_CLUSTER_NORMAL || 1167 ctype == QCOW2_CLUSTER_ZERO_ALLOC)) 1168 { 1169 bdrv_pdiscard(s->data_file, l2_entry & L2E_OFFSET_MASK, 1170 nb_clusters << s->cluster_bits); 1171 } 1172 return; 1173 } 1174 1175 switch (ctype) { 1176 case QCOW2_CLUSTER_COMPRESSED: 1177 { 1178 int64_t offset = (l2_entry & s->cluster_offset_mask) 1179 & QCOW2_COMPRESSED_SECTOR_MASK; 1180 int size = QCOW2_COMPRESSED_SECTOR_SIZE * 1181 (((l2_entry >> s->csize_shift) & s->csize_mask) + 1); 1182 qcow2_free_clusters(bs, offset, size, type); 1183 } 1184 break; 1185 case QCOW2_CLUSTER_NORMAL: 1186 case QCOW2_CLUSTER_ZERO_ALLOC: 1187 if (offset_into_cluster(s, l2_entry & L2E_OFFSET_MASK)) { 1188 qcow2_signal_corruption(bs, false, -1, -1, 1189 "Cannot free unaligned cluster %#llx", 1190 l2_entry & L2E_OFFSET_MASK); 1191 } else { 1192 qcow2_free_clusters(bs, l2_entry & L2E_OFFSET_MASK, 1193 nb_clusters << s->cluster_bits, type); 1194 } 1195 break; 1196 case QCOW2_CLUSTER_ZERO_PLAIN: 1197 case QCOW2_CLUSTER_UNALLOCATED: 1198 break; 1199 default: 1200 abort(); 1201 } 1202 } 1203 1204 int coroutine_fn qcow2_write_caches(BlockDriverState *bs) 1205 { 1206 BDRVQcow2State *s = bs->opaque; 1207 int ret; 1208 1209 ret = qcow2_cache_write(bs, s->l2_table_cache); 1210 if (ret < 0) { 1211 return ret; 1212 } 1213 1214 if (qcow2_need_accurate_refcounts(s)) { 1215 ret = qcow2_cache_write(bs, s->refcount_block_cache); 1216 if (ret < 0) { 1217 return ret; 1218 } 1219 } 1220 1221 return 0; 1222 } 1223 1224 int coroutine_fn qcow2_flush_caches(BlockDriverState *bs) 1225 { 1226 int ret = qcow2_write_caches(bs); 1227 if (ret < 0) { 1228 return ret; 1229 } 1230 1231 return bdrv_flush(bs->file->bs); 1232 } 1233 1234 /*********************************************************/ 1235 /* snapshots and image creation */ 1236 1237 1238 1239 /* update the refcounts of snapshots and the copied flag */ 1240 int qcow2_update_snapshot_refcount(BlockDriverState *bs, 1241 int64_t l1_table_offset, int l1_size, int addend) 1242 { 1243 BDRVQcow2State *s = bs->opaque; 1244 uint64_t *l1_table, *l2_slice, l2_offset, entry, l1_size2, refcount; 1245 bool l1_allocated = false; 1246 int64_t old_entry, old_l2_offset; 1247 unsigned slice, slice_size2, n_slices; 1248 int i, j, l1_modified = 0, nb_csectors; 1249 int ret; 1250 1251 assert(addend >= -1 && addend <= 1); 1252 1253 l2_slice = NULL; 1254 l1_table = NULL; 1255 l1_size2 = l1_size * sizeof(uint64_t); 1256 slice_size2 = s->l2_slice_size * sizeof(uint64_t); 1257 n_slices = s->cluster_size / slice_size2; 1258 1259 s->cache_discards = true; 1260 1261 /* WARNING: qcow2_snapshot_goto relies on this function not using the 1262 * l1_table_offset when it is the current s->l1_table_offset! Be careful 1263 * when changing this! */ 1264 if (l1_table_offset != s->l1_table_offset) { 1265 l1_table = g_try_malloc0(l1_size2); 1266 if (l1_size2 && l1_table == NULL) { 1267 ret = -ENOMEM; 1268 goto fail; 1269 } 1270 l1_allocated = true; 1271 1272 ret = bdrv_pread(bs->file, l1_table_offset, l1_table, l1_size2); 1273 if (ret < 0) { 1274 goto fail; 1275 } 1276 1277 for (i = 0; i < l1_size; i++) { 1278 be64_to_cpus(&l1_table[i]); 1279 } 1280 } else { 1281 assert(l1_size == s->l1_size); 1282 l1_table = s->l1_table; 1283 l1_allocated = false; 1284 } 1285 1286 for (i = 0; i < l1_size; i++) { 1287 l2_offset = l1_table[i]; 1288 if (l2_offset) { 1289 old_l2_offset = l2_offset; 1290 l2_offset &= L1E_OFFSET_MASK; 1291 1292 if (offset_into_cluster(s, l2_offset)) { 1293 qcow2_signal_corruption(bs, true, -1, -1, "L2 table offset %#" 1294 PRIx64 " unaligned (L1 index: %#x)", 1295 l2_offset, i); 1296 ret = -EIO; 1297 goto fail; 1298 } 1299 1300 for (slice = 0; slice < n_slices; slice++) { 1301 ret = qcow2_cache_get(bs, s->l2_table_cache, 1302 l2_offset + slice * slice_size2, 1303 (void **) &l2_slice); 1304 if (ret < 0) { 1305 goto fail; 1306 } 1307 1308 for (j = 0; j < s->l2_slice_size; j++) { 1309 uint64_t cluster_index; 1310 uint64_t offset; 1311 1312 entry = be64_to_cpu(l2_slice[j]); 1313 old_entry = entry; 1314 entry &= ~QCOW_OFLAG_COPIED; 1315 offset = entry & L2E_OFFSET_MASK; 1316 1317 switch (qcow2_get_cluster_type(bs, entry)) { 1318 case QCOW2_CLUSTER_COMPRESSED: 1319 nb_csectors = ((entry >> s->csize_shift) & 1320 s->csize_mask) + 1; 1321 if (addend != 0) { 1322 uint64_t coffset = (entry & s->cluster_offset_mask) 1323 & QCOW2_COMPRESSED_SECTOR_MASK; 1324 ret = update_refcount( 1325 bs, coffset, 1326 nb_csectors * QCOW2_COMPRESSED_SECTOR_SIZE, 1327 abs(addend), addend < 0, 1328 QCOW2_DISCARD_SNAPSHOT); 1329 if (ret < 0) { 1330 goto fail; 1331 } 1332 } 1333 /* compressed clusters are never modified */ 1334 refcount = 2; 1335 break; 1336 1337 case QCOW2_CLUSTER_NORMAL: 1338 case QCOW2_CLUSTER_ZERO_ALLOC: 1339 if (offset_into_cluster(s, offset)) { 1340 /* Here l2_index means table (not slice) index */ 1341 int l2_index = slice * s->l2_slice_size + j; 1342 qcow2_signal_corruption( 1343 bs, true, -1, -1, "Cluster " 1344 "allocation offset %#" PRIx64 1345 " unaligned (L2 offset: %#" 1346 PRIx64 ", L2 index: %#x)", 1347 offset, l2_offset, l2_index); 1348 ret = -EIO; 1349 goto fail; 1350 } 1351 1352 cluster_index = offset >> s->cluster_bits; 1353 assert(cluster_index); 1354 if (addend != 0) { 1355 ret = qcow2_update_cluster_refcount( 1356 bs, cluster_index, abs(addend), addend < 0, 1357 QCOW2_DISCARD_SNAPSHOT); 1358 if (ret < 0) { 1359 goto fail; 1360 } 1361 } 1362 1363 ret = qcow2_get_refcount(bs, cluster_index, &refcount); 1364 if (ret < 0) { 1365 goto fail; 1366 } 1367 break; 1368 1369 case QCOW2_CLUSTER_ZERO_PLAIN: 1370 case QCOW2_CLUSTER_UNALLOCATED: 1371 refcount = 0; 1372 break; 1373 1374 default: 1375 abort(); 1376 } 1377 1378 if (refcount == 1) { 1379 entry |= QCOW_OFLAG_COPIED; 1380 } 1381 if (entry != old_entry) { 1382 if (addend > 0) { 1383 qcow2_cache_set_dependency(bs, s->l2_table_cache, 1384 s->refcount_block_cache); 1385 } 1386 l2_slice[j] = cpu_to_be64(entry); 1387 qcow2_cache_entry_mark_dirty(s->l2_table_cache, 1388 l2_slice); 1389 } 1390 } 1391 1392 qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice); 1393 } 1394 1395 if (addend != 0) { 1396 ret = qcow2_update_cluster_refcount(bs, l2_offset >> 1397 s->cluster_bits, 1398 abs(addend), addend < 0, 1399 QCOW2_DISCARD_SNAPSHOT); 1400 if (ret < 0) { 1401 goto fail; 1402 } 1403 } 1404 ret = qcow2_get_refcount(bs, l2_offset >> s->cluster_bits, 1405 &refcount); 1406 if (ret < 0) { 1407 goto fail; 1408 } else if (refcount == 1) { 1409 l2_offset |= QCOW_OFLAG_COPIED; 1410 } 1411 if (l2_offset != old_l2_offset) { 1412 l1_table[i] = l2_offset; 1413 l1_modified = 1; 1414 } 1415 } 1416 } 1417 1418 ret = bdrv_flush(bs); 1419 fail: 1420 if (l2_slice) { 1421 qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice); 1422 } 1423 1424 s->cache_discards = false; 1425 qcow2_process_discards(bs, ret); 1426 1427 /* Update L1 only if it isn't deleted anyway (addend = -1) */ 1428 if (ret == 0 && addend >= 0 && l1_modified) { 1429 for (i = 0; i < l1_size; i++) { 1430 cpu_to_be64s(&l1_table[i]); 1431 } 1432 1433 ret = bdrv_pwrite_sync(bs->file, l1_table_offset, 1434 l1_table, l1_size2); 1435 1436 for (i = 0; i < l1_size; i++) { 1437 be64_to_cpus(&l1_table[i]); 1438 } 1439 } 1440 if (l1_allocated) 1441 g_free(l1_table); 1442 return ret; 1443 } 1444 1445 1446 1447 1448 /*********************************************************/ 1449 /* refcount checking functions */ 1450 1451 1452 static uint64_t refcount_array_byte_size(BDRVQcow2State *s, uint64_t entries) 1453 { 1454 /* This assertion holds because there is no way we can address more than 1455 * 2^(64 - 9) clusters at once (with cluster size 512 = 2^9, and because 1456 * offsets have to be representable in bytes); due to every cluster 1457 * corresponding to one refcount entry, we are well below that limit */ 1458 assert(entries < (UINT64_C(1) << (64 - 9))); 1459 1460 /* Thanks to the assertion this will not overflow, because 1461 * s->refcount_order < 7. 1462 * (note: x << s->refcount_order == x * s->refcount_bits) */ 1463 return DIV_ROUND_UP(entries << s->refcount_order, 8); 1464 } 1465 1466 /** 1467 * Reallocates *array so that it can hold new_size entries. *size must contain 1468 * the current number of entries in *array. If the reallocation fails, *array 1469 * and *size will not be modified and -errno will be returned. If the 1470 * reallocation is successful, *array will be set to the new buffer, *size 1471 * will be set to new_size and 0 will be returned. The size of the reallocated 1472 * refcount array buffer will be aligned to a cluster boundary, and the newly 1473 * allocated area will be zeroed. 1474 */ 1475 static int realloc_refcount_array(BDRVQcow2State *s, void **array, 1476 int64_t *size, int64_t new_size) 1477 { 1478 int64_t old_byte_size, new_byte_size; 1479 void *new_ptr; 1480 1481 /* Round to clusters so the array can be directly written to disk */ 1482 old_byte_size = size_to_clusters(s, refcount_array_byte_size(s, *size)) 1483 * s->cluster_size; 1484 new_byte_size = size_to_clusters(s, refcount_array_byte_size(s, new_size)) 1485 * s->cluster_size; 1486 1487 if (new_byte_size == old_byte_size) { 1488 *size = new_size; 1489 return 0; 1490 } 1491 1492 assert(new_byte_size > 0); 1493 1494 if (new_byte_size > SIZE_MAX) { 1495 return -ENOMEM; 1496 } 1497 1498 new_ptr = g_try_realloc(*array, new_byte_size); 1499 if (!new_ptr) { 1500 return -ENOMEM; 1501 } 1502 1503 if (new_byte_size > old_byte_size) { 1504 memset((char *)new_ptr + old_byte_size, 0, 1505 new_byte_size - old_byte_size); 1506 } 1507 1508 *array = new_ptr; 1509 *size = new_size; 1510 1511 return 0; 1512 } 1513 1514 /* 1515 * Increases the refcount for a range of clusters in a given refcount table. 1516 * This is used to construct a temporary refcount table out of L1 and L2 tables 1517 * which can be compared to the refcount table saved in the image. 1518 * 1519 * Modifies the number of errors in res. 1520 */ 1521 int qcow2_inc_refcounts_imrt(BlockDriverState *bs, BdrvCheckResult *res, 1522 void **refcount_table, 1523 int64_t *refcount_table_size, 1524 int64_t offset, int64_t size) 1525 { 1526 BDRVQcow2State *s = bs->opaque; 1527 uint64_t start, last, cluster_offset, k, refcount; 1528 int64_t file_len; 1529 int ret; 1530 1531 if (size <= 0) { 1532 return 0; 1533 } 1534 1535 file_len = bdrv_getlength(bs->file->bs); 1536 if (file_len < 0) { 1537 return file_len; 1538 } 1539 1540 /* 1541 * Last cluster of qcow2 image may be semi-allocated, so it may be OK to 1542 * reference some space after file end but it should be less than one 1543 * cluster. 1544 */ 1545 if (offset + size - file_len >= s->cluster_size) { 1546 fprintf(stderr, "ERROR: counting reference for region exceeding the " 1547 "end of the file by one cluster or more: offset 0x%" PRIx64 1548 " size 0x%" PRIx64 "\n", offset, size); 1549 res->corruptions++; 1550 return 0; 1551 } 1552 1553 start = start_of_cluster(s, offset); 1554 last = start_of_cluster(s, offset + size - 1); 1555 for(cluster_offset = start; cluster_offset <= last; 1556 cluster_offset += s->cluster_size) { 1557 k = cluster_offset >> s->cluster_bits; 1558 if (k >= *refcount_table_size) { 1559 ret = realloc_refcount_array(s, refcount_table, 1560 refcount_table_size, k + 1); 1561 if (ret < 0) { 1562 res->check_errors++; 1563 return ret; 1564 } 1565 } 1566 1567 refcount = s->get_refcount(*refcount_table, k); 1568 if (refcount == s->refcount_max) { 1569 fprintf(stderr, "ERROR: overflow cluster offset=0x%" PRIx64 1570 "\n", cluster_offset); 1571 fprintf(stderr, "Use qemu-img amend to increase the refcount entry " 1572 "width or qemu-img convert to create a clean copy if the " 1573 "image cannot be opened for writing\n"); 1574 res->corruptions++; 1575 continue; 1576 } 1577 s->set_refcount(*refcount_table, k, refcount + 1); 1578 } 1579 1580 return 0; 1581 } 1582 1583 /* Flags for check_refcounts_l1() and check_refcounts_l2() */ 1584 enum { 1585 CHECK_FRAG_INFO = 0x2, /* update BlockFragInfo counters */ 1586 }; 1587 1588 /* 1589 * Increases the refcount in the given refcount table for the all clusters 1590 * referenced in the L2 table. While doing so, performs some checks on L2 1591 * entries. 1592 * 1593 * Returns the number of errors found by the checks or -errno if an internal 1594 * error occurred. 1595 */ 1596 static int check_refcounts_l2(BlockDriverState *bs, BdrvCheckResult *res, 1597 void **refcount_table, 1598 int64_t *refcount_table_size, int64_t l2_offset, 1599 int flags, BdrvCheckMode fix, bool active) 1600 { 1601 BDRVQcow2State *s = bs->opaque; 1602 uint64_t *l2_table, l2_entry; 1603 uint64_t next_contiguous_offset = 0; 1604 int i, l2_size, nb_csectors, ret; 1605 1606 /* Read L2 table from disk */ 1607 l2_size = s->l2_size * sizeof(uint64_t); 1608 l2_table = g_malloc(l2_size); 1609 1610 ret = bdrv_pread(bs->file, l2_offset, l2_table, l2_size); 1611 if (ret < 0) { 1612 fprintf(stderr, "ERROR: I/O error in check_refcounts_l2\n"); 1613 res->check_errors++; 1614 goto fail; 1615 } 1616 1617 /* Do the actual checks */ 1618 for(i = 0; i < s->l2_size; i++) { 1619 l2_entry = be64_to_cpu(l2_table[i]); 1620 1621 switch (qcow2_get_cluster_type(bs, l2_entry)) { 1622 case QCOW2_CLUSTER_COMPRESSED: 1623 /* Compressed clusters don't have QCOW_OFLAG_COPIED */ 1624 if (l2_entry & QCOW_OFLAG_COPIED) { 1625 fprintf(stderr, "ERROR: coffset=0x%" PRIx64 ": " 1626 "copied flag must never be set for compressed " 1627 "clusters\n", l2_entry & s->cluster_offset_mask); 1628 l2_entry &= ~QCOW_OFLAG_COPIED; 1629 res->corruptions++; 1630 } 1631 1632 if (has_data_file(bs)) { 1633 fprintf(stderr, "ERROR compressed cluster %d with data file, " 1634 "entry=0x%" PRIx64 "\n", i, l2_entry); 1635 res->corruptions++; 1636 break; 1637 } 1638 1639 /* Mark cluster as used */ 1640 nb_csectors = ((l2_entry >> s->csize_shift) & 1641 s->csize_mask) + 1; 1642 l2_entry &= s->cluster_offset_mask; 1643 ret = qcow2_inc_refcounts_imrt( 1644 bs, res, refcount_table, refcount_table_size, 1645 l2_entry & QCOW2_COMPRESSED_SECTOR_MASK, 1646 nb_csectors * QCOW2_COMPRESSED_SECTOR_SIZE); 1647 if (ret < 0) { 1648 goto fail; 1649 } 1650 1651 if (flags & CHECK_FRAG_INFO) { 1652 res->bfi.allocated_clusters++; 1653 res->bfi.compressed_clusters++; 1654 1655 /* Compressed clusters are fragmented by nature. Since they 1656 * take up sub-sector space but we only have sector granularity 1657 * I/O we need to re-read the same sectors even for adjacent 1658 * compressed clusters. 1659 */ 1660 res->bfi.fragmented_clusters++; 1661 } 1662 break; 1663 1664 case QCOW2_CLUSTER_ZERO_ALLOC: 1665 case QCOW2_CLUSTER_NORMAL: 1666 { 1667 uint64_t offset = l2_entry & L2E_OFFSET_MASK; 1668 1669 /* Correct offsets are cluster aligned */ 1670 if (offset_into_cluster(s, offset)) { 1671 res->corruptions++; 1672 1673 if (qcow2_get_cluster_type(bs, l2_entry) == 1674 QCOW2_CLUSTER_ZERO_ALLOC) 1675 { 1676 fprintf(stderr, "%s offset=%" PRIx64 ": Preallocated zero " 1677 "cluster is not properly aligned; L2 entry " 1678 "corrupted.\n", 1679 fix & BDRV_FIX_ERRORS ? "Repairing" : "ERROR", 1680 offset); 1681 if (fix & BDRV_FIX_ERRORS) { 1682 uint64_t l2e_offset = 1683 l2_offset + (uint64_t)i * sizeof(uint64_t); 1684 int ign = active ? QCOW2_OL_ACTIVE_L2 : 1685 QCOW2_OL_INACTIVE_L2; 1686 1687 l2_entry = QCOW_OFLAG_ZERO; 1688 l2_table[i] = cpu_to_be64(l2_entry); 1689 ret = qcow2_pre_write_overlap_check(bs, ign, 1690 l2e_offset, sizeof(uint64_t), false); 1691 if (ret < 0) { 1692 fprintf(stderr, "ERROR: Overlap check failed\n"); 1693 res->check_errors++; 1694 /* Something is seriously wrong, so abort checking 1695 * this L2 table */ 1696 goto fail; 1697 } 1698 1699 ret = bdrv_pwrite_sync(bs->file, l2e_offset, 1700 &l2_table[i], sizeof(uint64_t)); 1701 if (ret < 0) { 1702 fprintf(stderr, "ERROR: Failed to overwrite L2 " 1703 "table entry: %s\n", strerror(-ret)); 1704 res->check_errors++; 1705 /* Do not abort, continue checking the rest of this 1706 * L2 table's entries */ 1707 } else { 1708 res->corruptions--; 1709 res->corruptions_fixed++; 1710 /* Skip marking the cluster as used 1711 * (it is unused now) */ 1712 continue; 1713 } 1714 } 1715 } else { 1716 fprintf(stderr, "ERROR offset=%" PRIx64 ": Data cluster is " 1717 "not properly aligned; L2 entry corrupted.\n", offset); 1718 } 1719 } 1720 1721 if (flags & CHECK_FRAG_INFO) { 1722 res->bfi.allocated_clusters++; 1723 if (next_contiguous_offset && 1724 offset != next_contiguous_offset) { 1725 res->bfi.fragmented_clusters++; 1726 } 1727 next_contiguous_offset = offset + s->cluster_size; 1728 } 1729 1730 /* Mark cluster as used */ 1731 if (!has_data_file(bs)) { 1732 ret = qcow2_inc_refcounts_imrt(bs, res, refcount_table, 1733 refcount_table_size, 1734 offset, s->cluster_size); 1735 if (ret < 0) { 1736 goto fail; 1737 } 1738 } 1739 break; 1740 } 1741 1742 case QCOW2_CLUSTER_ZERO_PLAIN: 1743 case QCOW2_CLUSTER_UNALLOCATED: 1744 break; 1745 1746 default: 1747 abort(); 1748 } 1749 } 1750 1751 g_free(l2_table); 1752 return 0; 1753 1754 fail: 1755 g_free(l2_table); 1756 return ret; 1757 } 1758 1759 /* 1760 * Increases the refcount for the L1 table, its L2 tables and all referenced 1761 * clusters in the given refcount table. While doing so, performs some checks 1762 * on L1 and L2 entries. 1763 * 1764 * Returns the number of errors found by the checks or -errno if an internal 1765 * error occurred. 1766 */ 1767 static int check_refcounts_l1(BlockDriverState *bs, 1768 BdrvCheckResult *res, 1769 void **refcount_table, 1770 int64_t *refcount_table_size, 1771 int64_t l1_table_offset, int l1_size, 1772 int flags, BdrvCheckMode fix, bool active) 1773 { 1774 BDRVQcow2State *s = bs->opaque; 1775 uint64_t *l1_table = NULL, l2_offset, l1_size2; 1776 int i, ret; 1777 1778 l1_size2 = l1_size * sizeof(uint64_t); 1779 1780 /* Mark L1 table as used */ 1781 ret = qcow2_inc_refcounts_imrt(bs, res, refcount_table, refcount_table_size, 1782 l1_table_offset, l1_size2); 1783 if (ret < 0) { 1784 goto fail; 1785 } 1786 1787 /* Read L1 table entries from disk */ 1788 if (l1_size2 > 0) { 1789 l1_table = g_try_malloc(l1_size2); 1790 if (l1_table == NULL) { 1791 ret = -ENOMEM; 1792 res->check_errors++; 1793 goto fail; 1794 } 1795 ret = bdrv_pread(bs->file, l1_table_offset, l1_table, l1_size2); 1796 if (ret < 0) { 1797 fprintf(stderr, "ERROR: I/O error in check_refcounts_l1\n"); 1798 res->check_errors++; 1799 goto fail; 1800 } 1801 for(i = 0;i < l1_size; i++) 1802 be64_to_cpus(&l1_table[i]); 1803 } 1804 1805 /* Do the actual checks */ 1806 for(i = 0; i < l1_size; i++) { 1807 l2_offset = l1_table[i]; 1808 if (l2_offset) { 1809 /* Mark L2 table as used */ 1810 l2_offset &= L1E_OFFSET_MASK; 1811 ret = qcow2_inc_refcounts_imrt(bs, res, 1812 refcount_table, refcount_table_size, 1813 l2_offset, s->cluster_size); 1814 if (ret < 0) { 1815 goto fail; 1816 } 1817 1818 /* L2 tables are cluster aligned */ 1819 if (offset_into_cluster(s, l2_offset)) { 1820 fprintf(stderr, "ERROR l2_offset=%" PRIx64 ": Table is not " 1821 "cluster aligned; L1 entry corrupted\n", l2_offset); 1822 res->corruptions++; 1823 } 1824 1825 /* Process and check L2 entries */ 1826 ret = check_refcounts_l2(bs, res, refcount_table, 1827 refcount_table_size, l2_offset, flags, 1828 fix, active); 1829 if (ret < 0) { 1830 goto fail; 1831 } 1832 } 1833 } 1834 g_free(l1_table); 1835 return 0; 1836 1837 fail: 1838 g_free(l1_table); 1839 return ret; 1840 } 1841 1842 /* 1843 * Checks the OFLAG_COPIED flag for all L1 and L2 entries. 1844 * 1845 * This function does not print an error message nor does it increment 1846 * check_errors if qcow2_get_refcount fails (this is because such an error will 1847 * have been already detected and sufficiently signaled by the calling function 1848 * (qcow2_check_refcounts) by the time this function is called). 1849 */ 1850 static int check_oflag_copied(BlockDriverState *bs, BdrvCheckResult *res, 1851 BdrvCheckMode fix) 1852 { 1853 BDRVQcow2State *s = bs->opaque; 1854 uint64_t *l2_table = qemu_blockalign(bs, s->cluster_size); 1855 int ret; 1856 uint64_t refcount; 1857 int i, j; 1858 bool repair; 1859 1860 if (fix & BDRV_FIX_ERRORS) { 1861 /* Always repair */ 1862 repair = true; 1863 } else if (fix & BDRV_FIX_LEAKS) { 1864 /* Repair only if that seems safe: This function is always 1865 * called after the refcounts have been fixed, so the refcount 1866 * is accurate if that repair was successful */ 1867 repair = !res->check_errors && !res->corruptions && !res->leaks; 1868 } else { 1869 repair = false; 1870 } 1871 1872 for (i = 0; i < s->l1_size; i++) { 1873 uint64_t l1_entry = s->l1_table[i]; 1874 uint64_t l2_offset = l1_entry & L1E_OFFSET_MASK; 1875 int l2_dirty = 0; 1876 1877 if (!l2_offset) { 1878 continue; 1879 } 1880 1881 ret = qcow2_get_refcount(bs, l2_offset >> s->cluster_bits, 1882 &refcount); 1883 if (ret < 0) { 1884 /* don't print message nor increment check_errors */ 1885 continue; 1886 } 1887 if ((refcount == 1) != ((l1_entry & QCOW_OFLAG_COPIED) != 0)) { 1888 res->corruptions++; 1889 fprintf(stderr, "%s OFLAG_COPIED L2 cluster: l1_index=%d " 1890 "l1_entry=%" PRIx64 " refcount=%" PRIu64 "\n", 1891 repair ? "Repairing" : "ERROR", i, l1_entry, refcount); 1892 if (repair) { 1893 s->l1_table[i] = refcount == 1 1894 ? l1_entry | QCOW_OFLAG_COPIED 1895 : l1_entry & ~QCOW_OFLAG_COPIED; 1896 ret = qcow2_write_l1_entry(bs, i); 1897 if (ret < 0) { 1898 res->check_errors++; 1899 goto fail; 1900 } 1901 res->corruptions--; 1902 res->corruptions_fixed++; 1903 } 1904 } 1905 1906 ret = bdrv_pread(bs->file, l2_offset, l2_table, 1907 s->l2_size * sizeof(uint64_t)); 1908 if (ret < 0) { 1909 fprintf(stderr, "ERROR: Could not read L2 table: %s\n", 1910 strerror(-ret)); 1911 res->check_errors++; 1912 goto fail; 1913 } 1914 1915 for (j = 0; j < s->l2_size; j++) { 1916 uint64_t l2_entry = be64_to_cpu(l2_table[j]); 1917 uint64_t data_offset = l2_entry & L2E_OFFSET_MASK; 1918 QCow2ClusterType cluster_type = qcow2_get_cluster_type(bs, l2_entry); 1919 1920 if (cluster_type == QCOW2_CLUSTER_NORMAL || 1921 cluster_type == QCOW2_CLUSTER_ZERO_ALLOC) { 1922 if (has_data_file(bs)) { 1923 refcount = 1; 1924 } else { 1925 ret = qcow2_get_refcount(bs, 1926 data_offset >> s->cluster_bits, 1927 &refcount); 1928 if (ret < 0) { 1929 /* don't print message nor increment check_errors */ 1930 continue; 1931 } 1932 } 1933 if ((refcount == 1) != ((l2_entry & QCOW_OFLAG_COPIED) != 0)) { 1934 res->corruptions++; 1935 fprintf(stderr, "%s OFLAG_COPIED data cluster: " 1936 "l2_entry=%" PRIx64 " refcount=%" PRIu64 "\n", 1937 repair ? "Repairing" : "ERROR", l2_entry, refcount); 1938 if (repair) { 1939 l2_table[j] = cpu_to_be64(refcount == 1 1940 ? l2_entry | QCOW_OFLAG_COPIED 1941 : l2_entry & ~QCOW_OFLAG_COPIED); 1942 l2_dirty++; 1943 } 1944 } 1945 } 1946 } 1947 1948 if (l2_dirty > 0) { 1949 ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_ACTIVE_L2, 1950 l2_offset, s->cluster_size, 1951 false); 1952 if (ret < 0) { 1953 fprintf(stderr, "ERROR: Could not write L2 table; metadata " 1954 "overlap check failed: %s\n", strerror(-ret)); 1955 res->check_errors++; 1956 goto fail; 1957 } 1958 1959 ret = bdrv_pwrite(bs->file, l2_offset, l2_table, 1960 s->cluster_size); 1961 if (ret < 0) { 1962 fprintf(stderr, "ERROR: Could not write L2 table: %s\n", 1963 strerror(-ret)); 1964 res->check_errors++; 1965 goto fail; 1966 } 1967 res->corruptions -= l2_dirty; 1968 res->corruptions_fixed += l2_dirty; 1969 } 1970 } 1971 1972 ret = 0; 1973 1974 fail: 1975 qemu_vfree(l2_table); 1976 return ret; 1977 } 1978 1979 /* 1980 * Checks consistency of refblocks and accounts for each refblock in 1981 * *refcount_table. 1982 */ 1983 static int check_refblocks(BlockDriverState *bs, BdrvCheckResult *res, 1984 BdrvCheckMode fix, bool *rebuild, 1985 void **refcount_table, int64_t *nb_clusters) 1986 { 1987 BDRVQcow2State *s = bs->opaque; 1988 int64_t i, size; 1989 int ret; 1990 1991 for(i = 0; i < s->refcount_table_size; i++) { 1992 uint64_t offset, cluster; 1993 offset = s->refcount_table[i]; 1994 cluster = offset >> s->cluster_bits; 1995 1996 /* Refcount blocks are cluster aligned */ 1997 if (offset_into_cluster(s, offset)) { 1998 fprintf(stderr, "ERROR refcount block %" PRId64 " is not " 1999 "cluster aligned; refcount table entry corrupted\n", i); 2000 res->corruptions++; 2001 *rebuild = true; 2002 continue; 2003 } 2004 2005 if (cluster >= *nb_clusters) { 2006 res->corruptions++; 2007 fprintf(stderr, "%s refcount block %" PRId64 " is outside image\n", 2008 fix & BDRV_FIX_ERRORS ? "Repairing" : "ERROR", i); 2009 2010 if (fix & BDRV_FIX_ERRORS) { 2011 int64_t new_nb_clusters; 2012 Error *local_err = NULL; 2013 2014 if (offset > INT64_MAX - s->cluster_size) { 2015 ret = -EINVAL; 2016 goto resize_fail; 2017 } 2018 2019 ret = bdrv_truncate(bs->file, offset + s->cluster_size, false, 2020 PREALLOC_MODE_OFF, &local_err); 2021 if (ret < 0) { 2022 error_report_err(local_err); 2023 goto resize_fail; 2024 } 2025 size = bdrv_getlength(bs->file->bs); 2026 if (size < 0) { 2027 ret = size; 2028 goto resize_fail; 2029 } 2030 2031 new_nb_clusters = size_to_clusters(s, size); 2032 assert(new_nb_clusters >= *nb_clusters); 2033 2034 ret = realloc_refcount_array(s, refcount_table, 2035 nb_clusters, new_nb_clusters); 2036 if (ret < 0) { 2037 res->check_errors++; 2038 return ret; 2039 } 2040 2041 if (cluster >= *nb_clusters) { 2042 ret = -EINVAL; 2043 goto resize_fail; 2044 } 2045 2046 res->corruptions--; 2047 res->corruptions_fixed++; 2048 ret = qcow2_inc_refcounts_imrt(bs, res, 2049 refcount_table, nb_clusters, 2050 offset, s->cluster_size); 2051 if (ret < 0) { 2052 return ret; 2053 } 2054 /* No need to check whether the refcount is now greater than 1: 2055 * This area was just allocated and zeroed, so it can only be 2056 * exactly 1 after qcow2_inc_refcounts_imrt() */ 2057 continue; 2058 2059 resize_fail: 2060 *rebuild = true; 2061 fprintf(stderr, "ERROR could not resize image: %s\n", 2062 strerror(-ret)); 2063 } 2064 continue; 2065 } 2066 2067 if (offset != 0) { 2068 ret = qcow2_inc_refcounts_imrt(bs, res, refcount_table, nb_clusters, 2069 offset, s->cluster_size); 2070 if (ret < 0) { 2071 return ret; 2072 } 2073 if (s->get_refcount(*refcount_table, cluster) != 1) { 2074 fprintf(stderr, "ERROR refcount block %" PRId64 2075 " refcount=%" PRIu64 "\n", i, 2076 s->get_refcount(*refcount_table, cluster)); 2077 res->corruptions++; 2078 *rebuild = true; 2079 } 2080 } 2081 } 2082 2083 return 0; 2084 } 2085 2086 /* 2087 * Calculates an in-memory refcount table. 2088 */ 2089 static int calculate_refcounts(BlockDriverState *bs, BdrvCheckResult *res, 2090 BdrvCheckMode fix, bool *rebuild, 2091 void **refcount_table, int64_t *nb_clusters) 2092 { 2093 BDRVQcow2State *s = bs->opaque; 2094 int64_t i; 2095 QCowSnapshot *sn; 2096 int ret; 2097 2098 if (!*refcount_table) { 2099 int64_t old_size = 0; 2100 ret = realloc_refcount_array(s, refcount_table, 2101 &old_size, *nb_clusters); 2102 if (ret < 0) { 2103 res->check_errors++; 2104 return ret; 2105 } 2106 } 2107 2108 /* header */ 2109 ret = qcow2_inc_refcounts_imrt(bs, res, refcount_table, nb_clusters, 2110 0, s->cluster_size); 2111 if (ret < 0) { 2112 return ret; 2113 } 2114 2115 /* current L1 table */ 2116 ret = check_refcounts_l1(bs, res, refcount_table, nb_clusters, 2117 s->l1_table_offset, s->l1_size, CHECK_FRAG_INFO, 2118 fix, true); 2119 if (ret < 0) { 2120 return ret; 2121 } 2122 2123 /* snapshots */ 2124 if (has_data_file(bs) && s->nb_snapshots) { 2125 fprintf(stderr, "ERROR %d snapshots in image with data file\n", 2126 s->nb_snapshots); 2127 res->corruptions++; 2128 } 2129 2130 for (i = 0; i < s->nb_snapshots; i++) { 2131 sn = s->snapshots + i; 2132 if (offset_into_cluster(s, sn->l1_table_offset)) { 2133 fprintf(stderr, "ERROR snapshot %s (%s) l1_offset=%#" PRIx64 ": " 2134 "L1 table is not cluster aligned; snapshot table entry " 2135 "corrupted\n", sn->id_str, sn->name, sn->l1_table_offset); 2136 res->corruptions++; 2137 continue; 2138 } 2139 if (sn->l1_size > QCOW_MAX_L1_SIZE / sizeof(uint64_t)) { 2140 fprintf(stderr, "ERROR snapshot %s (%s) l1_size=%#" PRIx32 ": " 2141 "L1 table is too large; snapshot table entry corrupted\n", 2142 sn->id_str, sn->name, sn->l1_size); 2143 res->corruptions++; 2144 continue; 2145 } 2146 ret = check_refcounts_l1(bs, res, refcount_table, nb_clusters, 2147 sn->l1_table_offset, sn->l1_size, 0, fix, 2148 false); 2149 if (ret < 0) { 2150 return ret; 2151 } 2152 } 2153 ret = qcow2_inc_refcounts_imrt(bs, res, refcount_table, nb_clusters, 2154 s->snapshots_offset, s->snapshots_size); 2155 if (ret < 0) { 2156 return ret; 2157 } 2158 2159 /* refcount data */ 2160 ret = qcow2_inc_refcounts_imrt(bs, res, refcount_table, nb_clusters, 2161 s->refcount_table_offset, 2162 s->refcount_table_size * sizeof(uint64_t)); 2163 if (ret < 0) { 2164 return ret; 2165 } 2166 2167 /* encryption */ 2168 if (s->crypto_header.length) { 2169 ret = qcow2_inc_refcounts_imrt(bs, res, refcount_table, nb_clusters, 2170 s->crypto_header.offset, 2171 s->crypto_header.length); 2172 if (ret < 0) { 2173 return ret; 2174 } 2175 } 2176 2177 /* bitmaps */ 2178 ret = qcow2_check_bitmaps_refcounts(bs, res, refcount_table, nb_clusters); 2179 if (ret < 0) { 2180 return ret; 2181 } 2182 2183 return check_refblocks(bs, res, fix, rebuild, refcount_table, nb_clusters); 2184 } 2185 2186 /* 2187 * Compares the actual reference count for each cluster in the image against the 2188 * refcount as reported by the refcount structures on-disk. 2189 */ 2190 static void compare_refcounts(BlockDriverState *bs, BdrvCheckResult *res, 2191 BdrvCheckMode fix, bool *rebuild, 2192 int64_t *highest_cluster, 2193 void *refcount_table, int64_t nb_clusters) 2194 { 2195 BDRVQcow2State *s = bs->opaque; 2196 int64_t i; 2197 uint64_t refcount1, refcount2; 2198 int ret; 2199 2200 for (i = 0, *highest_cluster = 0; i < nb_clusters; i++) { 2201 ret = qcow2_get_refcount(bs, i, &refcount1); 2202 if (ret < 0) { 2203 fprintf(stderr, "Can't get refcount for cluster %" PRId64 ": %s\n", 2204 i, strerror(-ret)); 2205 res->check_errors++; 2206 continue; 2207 } 2208 2209 refcount2 = s->get_refcount(refcount_table, i); 2210 2211 if (refcount1 > 0 || refcount2 > 0) { 2212 *highest_cluster = i; 2213 } 2214 2215 if (refcount1 != refcount2) { 2216 /* Check if we're allowed to fix the mismatch */ 2217 int *num_fixed = NULL; 2218 if (refcount1 == 0) { 2219 *rebuild = true; 2220 } else if (refcount1 > refcount2 && (fix & BDRV_FIX_LEAKS)) { 2221 num_fixed = &res->leaks_fixed; 2222 } else if (refcount1 < refcount2 && (fix & BDRV_FIX_ERRORS)) { 2223 num_fixed = &res->corruptions_fixed; 2224 } 2225 2226 fprintf(stderr, "%s cluster %" PRId64 " refcount=%" PRIu64 2227 " reference=%" PRIu64 "\n", 2228 num_fixed != NULL ? "Repairing" : 2229 refcount1 < refcount2 ? "ERROR" : 2230 "Leaked", 2231 i, refcount1, refcount2); 2232 2233 if (num_fixed) { 2234 ret = update_refcount(bs, i << s->cluster_bits, 1, 2235 refcount_diff(refcount1, refcount2), 2236 refcount1 > refcount2, 2237 QCOW2_DISCARD_ALWAYS); 2238 if (ret >= 0) { 2239 (*num_fixed)++; 2240 continue; 2241 } 2242 } 2243 2244 /* And if we couldn't, print an error */ 2245 if (refcount1 < refcount2) { 2246 res->corruptions++; 2247 } else { 2248 res->leaks++; 2249 } 2250 } 2251 } 2252 } 2253 2254 /* 2255 * Allocates clusters using an in-memory refcount table (IMRT) in contrast to 2256 * the on-disk refcount structures. 2257 * 2258 * On input, *first_free_cluster tells where to start looking, and need not 2259 * actually be a free cluster; the returned offset will not be before that 2260 * cluster. On output, *first_free_cluster points to the first gap found, even 2261 * if that gap was too small to be used as the returned offset. 2262 * 2263 * Note that *first_free_cluster is a cluster index whereas the return value is 2264 * an offset. 2265 */ 2266 static int64_t alloc_clusters_imrt(BlockDriverState *bs, 2267 int cluster_count, 2268 void **refcount_table, 2269 int64_t *imrt_nb_clusters, 2270 int64_t *first_free_cluster) 2271 { 2272 BDRVQcow2State *s = bs->opaque; 2273 int64_t cluster = *first_free_cluster, i; 2274 bool first_gap = true; 2275 int contiguous_free_clusters; 2276 int ret; 2277 2278 /* Starting at *first_free_cluster, find a range of at least cluster_count 2279 * continuously free clusters */ 2280 for (contiguous_free_clusters = 0; 2281 cluster < *imrt_nb_clusters && 2282 contiguous_free_clusters < cluster_count; 2283 cluster++) 2284 { 2285 if (!s->get_refcount(*refcount_table, cluster)) { 2286 contiguous_free_clusters++; 2287 if (first_gap) { 2288 /* If this is the first free cluster found, update 2289 * *first_free_cluster accordingly */ 2290 *first_free_cluster = cluster; 2291 first_gap = false; 2292 } 2293 } else if (contiguous_free_clusters) { 2294 contiguous_free_clusters = 0; 2295 } 2296 } 2297 2298 /* If contiguous_free_clusters is greater than zero, it contains the number 2299 * of continuously free clusters until the current cluster; the first free 2300 * cluster in the current "gap" is therefore 2301 * cluster - contiguous_free_clusters */ 2302 2303 /* If no such range could be found, grow the in-memory refcount table 2304 * accordingly to append free clusters at the end of the image */ 2305 if (contiguous_free_clusters < cluster_count) { 2306 /* contiguous_free_clusters clusters are already empty at the image end; 2307 * we need cluster_count clusters; therefore, we have to allocate 2308 * cluster_count - contiguous_free_clusters new clusters at the end of 2309 * the image (which is the current value of cluster; note that cluster 2310 * may exceed old_imrt_nb_clusters if *first_free_cluster pointed beyond 2311 * the image end) */ 2312 ret = realloc_refcount_array(s, refcount_table, imrt_nb_clusters, 2313 cluster + cluster_count 2314 - contiguous_free_clusters); 2315 if (ret < 0) { 2316 return ret; 2317 } 2318 } 2319 2320 /* Go back to the first free cluster */ 2321 cluster -= contiguous_free_clusters; 2322 for (i = 0; i < cluster_count; i++) { 2323 s->set_refcount(*refcount_table, cluster + i, 1); 2324 } 2325 2326 return cluster << s->cluster_bits; 2327 } 2328 2329 /* 2330 * Creates a new refcount structure based solely on the in-memory information 2331 * given through *refcount_table. All necessary allocations will be reflected 2332 * in that array. 2333 * 2334 * On success, the old refcount structure is leaked (it will be covered by the 2335 * new refcount structure). 2336 */ 2337 static int rebuild_refcount_structure(BlockDriverState *bs, 2338 BdrvCheckResult *res, 2339 void **refcount_table, 2340 int64_t *nb_clusters) 2341 { 2342 BDRVQcow2State *s = bs->opaque; 2343 int64_t first_free_cluster = 0, reftable_offset = -1, cluster = 0; 2344 int64_t refblock_offset, refblock_start, refblock_index; 2345 uint32_t reftable_size = 0; 2346 uint64_t *on_disk_reftable = NULL; 2347 void *on_disk_refblock; 2348 int ret = 0; 2349 struct { 2350 uint64_t reftable_offset; 2351 uint32_t reftable_clusters; 2352 } QEMU_PACKED reftable_offset_and_clusters; 2353 2354 qcow2_cache_empty(bs, s->refcount_block_cache); 2355 2356 write_refblocks: 2357 for (; cluster < *nb_clusters; cluster++) { 2358 if (!s->get_refcount(*refcount_table, cluster)) { 2359 continue; 2360 } 2361 2362 refblock_index = cluster >> s->refcount_block_bits; 2363 refblock_start = refblock_index << s->refcount_block_bits; 2364 2365 /* Don't allocate a cluster in a refblock already written to disk */ 2366 if (first_free_cluster < refblock_start) { 2367 first_free_cluster = refblock_start; 2368 } 2369 refblock_offset = alloc_clusters_imrt(bs, 1, refcount_table, 2370 nb_clusters, &first_free_cluster); 2371 if (refblock_offset < 0) { 2372 fprintf(stderr, "ERROR allocating refblock: %s\n", 2373 strerror(-refblock_offset)); 2374 res->check_errors++; 2375 ret = refblock_offset; 2376 goto fail; 2377 } 2378 2379 if (reftable_size <= refblock_index) { 2380 uint32_t old_reftable_size = reftable_size; 2381 uint64_t *new_on_disk_reftable; 2382 2383 reftable_size = ROUND_UP((refblock_index + 1) * sizeof(uint64_t), 2384 s->cluster_size) / sizeof(uint64_t); 2385 new_on_disk_reftable = g_try_realloc(on_disk_reftable, 2386 reftable_size * 2387 sizeof(uint64_t)); 2388 if (!new_on_disk_reftable) { 2389 res->check_errors++; 2390 ret = -ENOMEM; 2391 goto fail; 2392 } 2393 on_disk_reftable = new_on_disk_reftable; 2394 2395 memset(on_disk_reftable + old_reftable_size, 0, 2396 (reftable_size - old_reftable_size) * sizeof(uint64_t)); 2397 2398 /* The offset we have for the reftable is now no longer valid; 2399 * this will leak that range, but we can easily fix that by running 2400 * a leak-fixing check after this rebuild operation */ 2401 reftable_offset = -1; 2402 } else { 2403 assert(on_disk_reftable); 2404 } 2405 on_disk_reftable[refblock_index] = refblock_offset; 2406 2407 /* If this is apparently the last refblock (for now), try to squeeze the 2408 * reftable in */ 2409 if (refblock_index == (*nb_clusters - 1) >> s->refcount_block_bits && 2410 reftable_offset < 0) 2411 { 2412 uint64_t reftable_clusters = size_to_clusters(s, reftable_size * 2413 sizeof(uint64_t)); 2414 reftable_offset = alloc_clusters_imrt(bs, reftable_clusters, 2415 refcount_table, nb_clusters, 2416 &first_free_cluster); 2417 if (reftable_offset < 0) { 2418 fprintf(stderr, "ERROR allocating reftable: %s\n", 2419 strerror(-reftable_offset)); 2420 res->check_errors++; 2421 ret = reftable_offset; 2422 goto fail; 2423 } 2424 } 2425 2426 ret = qcow2_pre_write_overlap_check(bs, 0, refblock_offset, 2427 s->cluster_size, false); 2428 if (ret < 0) { 2429 fprintf(stderr, "ERROR writing refblock: %s\n", strerror(-ret)); 2430 goto fail; 2431 } 2432 2433 /* The size of *refcount_table is always cluster-aligned, therefore the 2434 * write operation will not overflow */ 2435 on_disk_refblock = (void *)((char *) *refcount_table + 2436 refblock_index * s->cluster_size); 2437 2438 ret = bdrv_pwrite(bs->file, refblock_offset, on_disk_refblock, 2439 s->cluster_size); 2440 if (ret < 0) { 2441 fprintf(stderr, "ERROR writing refblock: %s\n", strerror(-ret)); 2442 goto fail; 2443 } 2444 2445 /* Go to the end of this refblock */ 2446 cluster = refblock_start + s->refcount_block_size - 1; 2447 } 2448 2449 if (reftable_offset < 0) { 2450 uint64_t post_refblock_start, reftable_clusters; 2451 2452 post_refblock_start = ROUND_UP(*nb_clusters, s->refcount_block_size); 2453 reftable_clusters = size_to_clusters(s, 2454 reftable_size * sizeof(uint64_t)); 2455 /* Not pretty but simple */ 2456 if (first_free_cluster < post_refblock_start) { 2457 first_free_cluster = post_refblock_start; 2458 } 2459 reftable_offset = alloc_clusters_imrt(bs, reftable_clusters, 2460 refcount_table, nb_clusters, 2461 &first_free_cluster); 2462 if (reftable_offset < 0) { 2463 fprintf(stderr, "ERROR allocating reftable: %s\n", 2464 strerror(-reftable_offset)); 2465 res->check_errors++; 2466 ret = reftable_offset; 2467 goto fail; 2468 } 2469 2470 goto write_refblocks; 2471 } 2472 2473 for (refblock_index = 0; refblock_index < reftable_size; refblock_index++) { 2474 cpu_to_be64s(&on_disk_reftable[refblock_index]); 2475 } 2476 2477 ret = qcow2_pre_write_overlap_check(bs, 0, reftable_offset, 2478 reftable_size * sizeof(uint64_t), 2479 false); 2480 if (ret < 0) { 2481 fprintf(stderr, "ERROR writing reftable: %s\n", strerror(-ret)); 2482 goto fail; 2483 } 2484 2485 assert(reftable_size < INT_MAX / sizeof(uint64_t)); 2486 ret = bdrv_pwrite(bs->file, reftable_offset, on_disk_reftable, 2487 reftable_size * sizeof(uint64_t)); 2488 if (ret < 0) { 2489 fprintf(stderr, "ERROR writing reftable: %s\n", strerror(-ret)); 2490 goto fail; 2491 } 2492 2493 /* Enter new reftable into the image header */ 2494 reftable_offset_and_clusters.reftable_offset = cpu_to_be64(reftable_offset); 2495 reftable_offset_and_clusters.reftable_clusters = 2496 cpu_to_be32(size_to_clusters(s, reftable_size * sizeof(uint64_t))); 2497 ret = bdrv_pwrite_sync(bs->file, 2498 offsetof(QCowHeader, refcount_table_offset), 2499 &reftable_offset_and_clusters, 2500 sizeof(reftable_offset_and_clusters)); 2501 if (ret < 0) { 2502 fprintf(stderr, "ERROR setting reftable: %s\n", strerror(-ret)); 2503 goto fail; 2504 } 2505 2506 for (refblock_index = 0; refblock_index < reftable_size; refblock_index++) { 2507 be64_to_cpus(&on_disk_reftable[refblock_index]); 2508 } 2509 s->refcount_table = on_disk_reftable; 2510 s->refcount_table_offset = reftable_offset; 2511 s->refcount_table_size = reftable_size; 2512 update_max_refcount_table_index(s); 2513 2514 return 0; 2515 2516 fail: 2517 g_free(on_disk_reftable); 2518 return ret; 2519 } 2520 2521 /* 2522 * Checks an image for refcount consistency. 2523 * 2524 * Returns 0 if no errors are found, the number of errors in case the image is 2525 * detected as corrupted, and -errno when an internal error occurred. 2526 */ 2527 int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res, 2528 BdrvCheckMode fix) 2529 { 2530 BDRVQcow2State *s = bs->opaque; 2531 BdrvCheckResult pre_compare_res; 2532 int64_t size, highest_cluster, nb_clusters; 2533 void *refcount_table = NULL; 2534 bool rebuild = false; 2535 int ret; 2536 2537 size = bdrv_getlength(bs->file->bs); 2538 if (size < 0) { 2539 res->check_errors++; 2540 return size; 2541 } 2542 2543 nb_clusters = size_to_clusters(s, size); 2544 if (nb_clusters > INT_MAX) { 2545 res->check_errors++; 2546 return -EFBIG; 2547 } 2548 2549 res->bfi.total_clusters = 2550 size_to_clusters(s, bs->total_sectors * BDRV_SECTOR_SIZE); 2551 2552 ret = calculate_refcounts(bs, res, fix, &rebuild, &refcount_table, 2553 &nb_clusters); 2554 if (ret < 0) { 2555 goto fail; 2556 } 2557 2558 /* In case we don't need to rebuild the refcount structure (but want to fix 2559 * something), this function is immediately called again, in which case the 2560 * result should be ignored */ 2561 pre_compare_res = *res; 2562 compare_refcounts(bs, res, 0, &rebuild, &highest_cluster, refcount_table, 2563 nb_clusters); 2564 2565 if (rebuild && (fix & BDRV_FIX_ERRORS)) { 2566 BdrvCheckResult old_res = *res; 2567 int fresh_leaks = 0; 2568 2569 fprintf(stderr, "Rebuilding refcount structure\n"); 2570 ret = rebuild_refcount_structure(bs, res, &refcount_table, 2571 &nb_clusters); 2572 if (ret < 0) { 2573 goto fail; 2574 } 2575 2576 res->corruptions = 0; 2577 res->leaks = 0; 2578 2579 /* Because the old reftable has been exchanged for a new one the 2580 * references have to be recalculated */ 2581 rebuild = false; 2582 memset(refcount_table, 0, refcount_array_byte_size(s, nb_clusters)); 2583 ret = calculate_refcounts(bs, res, 0, &rebuild, &refcount_table, 2584 &nb_clusters); 2585 if (ret < 0) { 2586 goto fail; 2587 } 2588 2589 if (fix & BDRV_FIX_LEAKS) { 2590 /* The old refcount structures are now leaked, fix it; the result 2591 * can be ignored, aside from leaks which were introduced by 2592 * rebuild_refcount_structure() that could not be fixed */ 2593 BdrvCheckResult saved_res = *res; 2594 *res = (BdrvCheckResult){ 0 }; 2595 2596 compare_refcounts(bs, res, BDRV_FIX_LEAKS, &rebuild, 2597 &highest_cluster, refcount_table, nb_clusters); 2598 if (rebuild) { 2599 fprintf(stderr, "ERROR rebuilt refcount structure is still " 2600 "broken\n"); 2601 } 2602 2603 /* Any leaks accounted for here were introduced by 2604 * rebuild_refcount_structure() because that function has created a 2605 * new refcount structure from scratch */ 2606 fresh_leaks = res->leaks; 2607 *res = saved_res; 2608 } 2609 2610 if (res->corruptions < old_res.corruptions) { 2611 res->corruptions_fixed += old_res.corruptions - res->corruptions; 2612 } 2613 if (res->leaks < old_res.leaks) { 2614 res->leaks_fixed += old_res.leaks - res->leaks; 2615 } 2616 res->leaks += fresh_leaks; 2617 } else if (fix) { 2618 if (rebuild) { 2619 fprintf(stderr, "ERROR need to rebuild refcount structures\n"); 2620 res->check_errors++; 2621 ret = -EIO; 2622 goto fail; 2623 } 2624 2625 if (res->leaks || res->corruptions) { 2626 *res = pre_compare_res; 2627 compare_refcounts(bs, res, fix, &rebuild, &highest_cluster, 2628 refcount_table, nb_clusters); 2629 } 2630 } 2631 2632 /* check OFLAG_COPIED */ 2633 ret = check_oflag_copied(bs, res, fix); 2634 if (ret < 0) { 2635 goto fail; 2636 } 2637 2638 res->image_end_offset = (highest_cluster + 1) * s->cluster_size; 2639 ret = 0; 2640 2641 fail: 2642 g_free(refcount_table); 2643 2644 return ret; 2645 } 2646 2647 #define overlaps_with(ofs, sz) \ 2648 ranges_overlap(offset, size, ofs, sz) 2649 2650 /* 2651 * Checks if the given offset into the image file is actually free to use by 2652 * looking for overlaps with important metadata sections (L1/L2 tables etc.), 2653 * i.e. a sanity check without relying on the refcount tables. 2654 * 2655 * The ign parameter specifies what checks not to perform (being a bitmask of 2656 * QCow2MetadataOverlap values), i.e., what sections to ignore. 2657 * 2658 * Returns: 2659 * - 0 if writing to this offset will not affect the mentioned metadata 2660 * - a positive QCow2MetadataOverlap value indicating one overlapping section 2661 * - a negative value (-errno) indicating an error while performing a check, 2662 * e.g. when bdrv_read failed on QCOW2_OL_INACTIVE_L2 2663 */ 2664 int qcow2_check_metadata_overlap(BlockDriverState *bs, int ign, int64_t offset, 2665 int64_t size) 2666 { 2667 BDRVQcow2State *s = bs->opaque; 2668 int chk = s->overlap_check & ~ign; 2669 int i, j; 2670 2671 if (!size) { 2672 return 0; 2673 } 2674 2675 if (chk & QCOW2_OL_MAIN_HEADER) { 2676 if (offset < s->cluster_size) { 2677 return QCOW2_OL_MAIN_HEADER; 2678 } 2679 } 2680 2681 /* align range to test to cluster boundaries */ 2682 size = ROUND_UP(offset_into_cluster(s, offset) + size, s->cluster_size); 2683 offset = start_of_cluster(s, offset); 2684 2685 if ((chk & QCOW2_OL_ACTIVE_L1) && s->l1_size) { 2686 if (overlaps_with(s->l1_table_offset, s->l1_size * sizeof(uint64_t))) { 2687 return QCOW2_OL_ACTIVE_L1; 2688 } 2689 } 2690 2691 if ((chk & QCOW2_OL_REFCOUNT_TABLE) && s->refcount_table_size) { 2692 if (overlaps_with(s->refcount_table_offset, 2693 s->refcount_table_size * sizeof(uint64_t))) { 2694 return QCOW2_OL_REFCOUNT_TABLE; 2695 } 2696 } 2697 2698 if ((chk & QCOW2_OL_SNAPSHOT_TABLE) && s->snapshots_size) { 2699 if (overlaps_with(s->snapshots_offset, s->snapshots_size)) { 2700 return QCOW2_OL_SNAPSHOT_TABLE; 2701 } 2702 } 2703 2704 if ((chk & QCOW2_OL_INACTIVE_L1) && s->snapshots) { 2705 for (i = 0; i < s->nb_snapshots; i++) { 2706 if (s->snapshots[i].l1_size && 2707 overlaps_with(s->snapshots[i].l1_table_offset, 2708 s->snapshots[i].l1_size * sizeof(uint64_t))) { 2709 return QCOW2_OL_INACTIVE_L1; 2710 } 2711 } 2712 } 2713 2714 if ((chk & QCOW2_OL_ACTIVE_L2) && s->l1_table) { 2715 for (i = 0; i < s->l1_size; i++) { 2716 if ((s->l1_table[i] & L1E_OFFSET_MASK) && 2717 overlaps_with(s->l1_table[i] & L1E_OFFSET_MASK, 2718 s->cluster_size)) { 2719 return QCOW2_OL_ACTIVE_L2; 2720 } 2721 } 2722 } 2723 2724 if ((chk & QCOW2_OL_REFCOUNT_BLOCK) && s->refcount_table) { 2725 unsigned last_entry = s->max_refcount_table_index; 2726 assert(last_entry < s->refcount_table_size); 2727 assert(last_entry + 1 == s->refcount_table_size || 2728 (s->refcount_table[last_entry + 1] & REFT_OFFSET_MASK) == 0); 2729 for (i = 0; i <= last_entry; i++) { 2730 if ((s->refcount_table[i] & REFT_OFFSET_MASK) && 2731 overlaps_with(s->refcount_table[i] & REFT_OFFSET_MASK, 2732 s->cluster_size)) { 2733 return QCOW2_OL_REFCOUNT_BLOCK; 2734 } 2735 } 2736 } 2737 2738 if ((chk & QCOW2_OL_INACTIVE_L2) && s->snapshots) { 2739 for (i = 0; i < s->nb_snapshots; i++) { 2740 uint64_t l1_ofs = s->snapshots[i].l1_table_offset; 2741 uint32_t l1_sz = s->snapshots[i].l1_size; 2742 uint64_t l1_sz2 = l1_sz * sizeof(uint64_t); 2743 uint64_t *l1; 2744 int ret; 2745 2746 ret = qcow2_validate_table(bs, l1_ofs, l1_sz, sizeof(uint64_t), 2747 QCOW_MAX_L1_SIZE, "", NULL); 2748 if (ret < 0) { 2749 return ret; 2750 } 2751 2752 l1 = g_try_malloc(l1_sz2); 2753 2754 if (l1_sz2 && l1 == NULL) { 2755 return -ENOMEM; 2756 } 2757 2758 ret = bdrv_pread(bs->file, l1_ofs, l1, l1_sz2); 2759 if (ret < 0) { 2760 g_free(l1); 2761 return ret; 2762 } 2763 2764 for (j = 0; j < l1_sz; j++) { 2765 uint64_t l2_ofs = be64_to_cpu(l1[j]) & L1E_OFFSET_MASK; 2766 if (l2_ofs && overlaps_with(l2_ofs, s->cluster_size)) { 2767 g_free(l1); 2768 return QCOW2_OL_INACTIVE_L2; 2769 } 2770 } 2771 2772 g_free(l1); 2773 } 2774 } 2775 2776 if ((chk & QCOW2_OL_BITMAP_DIRECTORY) && 2777 (s->autoclear_features & QCOW2_AUTOCLEAR_BITMAPS)) 2778 { 2779 if (overlaps_with(s->bitmap_directory_offset, 2780 s->bitmap_directory_size)) 2781 { 2782 return QCOW2_OL_BITMAP_DIRECTORY; 2783 } 2784 } 2785 2786 return 0; 2787 } 2788 2789 static const char *metadata_ol_names[] = { 2790 [QCOW2_OL_MAIN_HEADER_BITNR] = "qcow2_header", 2791 [QCOW2_OL_ACTIVE_L1_BITNR] = "active L1 table", 2792 [QCOW2_OL_ACTIVE_L2_BITNR] = "active L2 table", 2793 [QCOW2_OL_REFCOUNT_TABLE_BITNR] = "refcount table", 2794 [QCOW2_OL_REFCOUNT_BLOCK_BITNR] = "refcount block", 2795 [QCOW2_OL_SNAPSHOT_TABLE_BITNR] = "snapshot table", 2796 [QCOW2_OL_INACTIVE_L1_BITNR] = "inactive L1 table", 2797 [QCOW2_OL_INACTIVE_L2_BITNR] = "inactive L2 table", 2798 [QCOW2_OL_BITMAP_DIRECTORY_BITNR] = "bitmap directory", 2799 }; 2800 QEMU_BUILD_BUG_ON(QCOW2_OL_MAX_BITNR != ARRAY_SIZE(metadata_ol_names)); 2801 2802 /* 2803 * First performs a check for metadata overlaps (through 2804 * qcow2_check_metadata_overlap); if that fails with a negative value (error 2805 * while performing a check), that value is returned. If an impending overlap 2806 * is detected, the BDS will be made unusable, the qcow2 file marked corrupt 2807 * and -EIO returned. 2808 * 2809 * Returns 0 if there were neither overlaps nor errors while checking for 2810 * overlaps; or a negative value (-errno) on error. 2811 */ 2812 int qcow2_pre_write_overlap_check(BlockDriverState *bs, int ign, int64_t offset, 2813 int64_t size, bool data_file) 2814 { 2815 int ret; 2816 2817 if (data_file && has_data_file(bs)) { 2818 return 0; 2819 } 2820 2821 ret = qcow2_check_metadata_overlap(bs, ign, offset, size); 2822 if (ret < 0) { 2823 return ret; 2824 } else if (ret > 0) { 2825 int metadata_ol_bitnr = ctz32(ret); 2826 assert(metadata_ol_bitnr < QCOW2_OL_MAX_BITNR); 2827 2828 qcow2_signal_corruption(bs, true, offset, size, "Preventing invalid " 2829 "write on metadata (overlaps with %s)", 2830 metadata_ol_names[metadata_ol_bitnr]); 2831 return -EIO; 2832 } 2833 2834 return 0; 2835 } 2836 2837 /* A pointer to a function of this type is given to walk_over_reftable(). That 2838 * function will create refblocks and pass them to a RefblockFinishOp once they 2839 * are completed (@refblock). @refblock_empty is set if the refblock is 2840 * completely empty. 2841 * 2842 * Along with the refblock, a corresponding reftable entry is passed, in the 2843 * reftable @reftable (which may be reallocated) at @reftable_index. 2844 * 2845 * @allocated should be set to true if a new cluster has been allocated. 2846 */ 2847 typedef int (RefblockFinishOp)(BlockDriverState *bs, uint64_t **reftable, 2848 uint64_t reftable_index, uint64_t *reftable_size, 2849 void *refblock, bool refblock_empty, 2850 bool *allocated, Error **errp); 2851 2852 /** 2853 * This "operation" for walk_over_reftable() allocates the refblock on disk (if 2854 * it is not empty) and inserts its offset into the new reftable. The size of 2855 * this new reftable is increased as required. 2856 */ 2857 static int alloc_refblock(BlockDriverState *bs, uint64_t **reftable, 2858 uint64_t reftable_index, uint64_t *reftable_size, 2859 void *refblock, bool refblock_empty, bool *allocated, 2860 Error **errp) 2861 { 2862 BDRVQcow2State *s = bs->opaque; 2863 int64_t offset; 2864 2865 if (!refblock_empty && reftable_index >= *reftable_size) { 2866 uint64_t *new_reftable; 2867 uint64_t new_reftable_size; 2868 2869 new_reftable_size = ROUND_UP(reftable_index + 1, 2870 s->cluster_size / sizeof(uint64_t)); 2871 if (new_reftable_size > QCOW_MAX_REFTABLE_SIZE / sizeof(uint64_t)) { 2872 error_setg(errp, 2873 "This operation would make the refcount table grow " 2874 "beyond the maximum size supported by QEMU, aborting"); 2875 return -ENOTSUP; 2876 } 2877 2878 new_reftable = g_try_realloc(*reftable, new_reftable_size * 2879 sizeof(uint64_t)); 2880 if (!new_reftable) { 2881 error_setg(errp, "Failed to increase reftable buffer size"); 2882 return -ENOMEM; 2883 } 2884 2885 memset(new_reftable + *reftable_size, 0, 2886 (new_reftable_size - *reftable_size) * sizeof(uint64_t)); 2887 2888 *reftable = new_reftable; 2889 *reftable_size = new_reftable_size; 2890 } 2891 2892 if (!refblock_empty && !(*reftable)[reftable_index]) { 2893 offset = qcow2_alloc_clusters(bs, s->cluster_size); 2894 if (offset < 0) { 2895 error_setg_errno(errp, -offset, "Failed to allocate refblock"); 2896 return offset; 2897 } 2898 (*reftable)[reftable_index] = offset; 2899 *allocated = true; 2900 } 2901 2902 return 0; 2903 } 2904 2905 /** 2906 * This "operation" for walk_over_reftable() writes the refblock to disk at the 2907 * offset specified by the new reftable's entry. It does not modify the new 2908 * reftable or change any refcounts. 2909 */ 2910 static int flush_refblock(BlockDriverState *bs, uint64_t **reftable, 2911 uint64_t reftable_index, uint64_t *reftable_size, 2912 void *refblock, bool refblock_empty, bool *allocated, 2913 Error **errp) 2914 { 2915 BDRVQcow2State *s = bs->opaque; 2916 int64_t offset; 2917 int ret; 2918 2919 if (reftable_index < *reftable_size && (*reftable)[reftable_index]) { 2920 offset = (*reftable)[reftable_index]; 2921 2922 ret = qcow2_pre_write_overlap_check(bs, 0, offset, s->cluster_size, 2923 false); 2924 if (ret < 0) { 2925 error_setg_errno(errp, -ret, "Overlap check failed"); 2926 return ret; 2927 } 2928 2929 ret = bdrv_pwrite(bs->file, offset, refblock, s->cluster_size); 2930 if (ret < 0) { 2931 error_setg_errno(errp, -ret, "Failed to write refblock"); 2932 return ret; 2933 } 2934 } else { 2935 assert(refblock_empty); 2936 } 2937 2938 return 0; 2939 } 2940 2941 /** 2942 * This function walks over the existing reftable and every referenced refblock; 2943 * if @new_set_refcount is non-NULL, it is called for every refcount entry to 2944 * create an equal new entry in the passed @new_refblock. Once that 2945 * @new_refblock is completely filled, @operation will be called. 2946 * 2947 * @status_cb and @cb_opaque are used for the amend operation's status callback. 2948 * @index is the index of the walk_over_reftable() calls and @total is the total 2949 * number of walk_over_reftable() calls per amend operation. Both are used for 2950 * calculating the parameters for the status callback. 2951 * 2952 * @allocated is set to true if a new cluster has been allocated. 2953 */ 2954 static int walk_over_reftable(BlockDriverState *bs, uint64_t **new_reftable, 2955 uint64_t *new_reftable_index, 2956 uint64_t *new_reftable_size, 2957 void *new_refblock, int new_refblock_size, 2958 int new_refcount_bits, 2959 RefblockFinishOp *operation, bool *allocated, 2960 Qcow2SetRefcountFunc *new_set_refcount, 2961 BlockDriverAmendStatusCB *status_cb, 2962 void *cb_opaque, int index, int total, 2963 Error **errp) 2964 { 2965 BDRVQcow2State *s = bs->opaque; 2966 uint64_t reftable_index; 2967 bool new_refblock_empty = true; 2968 int refblock_index; 2969 int new_refblock_index = 0; 2970 int ret; 2971 2972 for (reftable_index = 0; reftable_index < s->refcount_table_size; 2973 reftable_index++) 2974 { 2975 uint64_t refblock_offset = s->refcount_table[reftable_index] 2976 & REFT_OFFSET_MASK; 2977 2978 status_cb(bs, (uint64_t)index * s->refcount_table_size + reftable_index, 2979 (uint64_t)total * s->refcount_table_size, cb_opaque); 2980 2981 if (refblock_offset) { 2982 void *refblock; 2983 2984 if (offset_into_cluster(s, refblock_offset)) { 2985 qcow2_signal_corruption(bs, true, -1, -1, "Refblock offset %#" 2986 PRIx64 " unaligned (reftable index: %#" 2987 PRIx64 ")", refblock_offset, 2988 reftable_index); 2989 error_setg(errp, 2990 "Image is corrupt (unaligned refblock offset)"); 2991 return -EIO; 2992 } 2993 2994 ret = qcow2_cache_get(bs, s->refcount_block_cache, refblock_offset, 2995 &refblock); 2996 if (ret < 0) { 2997 error_setg_errno(errp, -ret, "Failed to retrieve refblock"); 2998 return ret; 2999 } 3000 3001 for (refblock_index = 0; refblock_index < s->refcount_block_size; 3002 refblock_index++) 3003 { 3004 uint64_t refcount; 3005 3006 if (new_refblock_index >= new_refblock_size) { 3007 /* new_refblock is now complete */ 3008 ret = operation(bs, new_reftable, *new_reftable_index, 3009 new_reftable_size, new_refblock, 3010 new_refblock_empty, allocated, errp); 3011 if (ret < 0) { 3012 qcow2_cache_put(s->refcount_block_cache, &refblock); 3013 return ret; 3014 } 3015 3016 (*new_reftable_index)++; 3017 new_refblock_index = 0; 3018 new_refblock_empty = true; 3019 } 3020 3021 refcount = s->get_refcount(refblock, refblock_index); 3022 if (new_refcount_bits < 64 && refcount >> new_refcount_bits) { 3023 uint64_t offset; 3024 3025 qcow2_cache_put(s->refcount_block_cache, &refblock); 3026 3027 offset = ((reftable_index << s->refcount_block_bits) 3028 + refblock_index) << s->cluster_bits; 3029 3030 error_setg(errp, "Cannot decrease refcount entry width to " 3031 "%i bits: Cluster at offset %#" PRIx64 " has a " 3032 "refcount of %" PRIu64, new_refcount_bits, 3033 offset, refcount); 3034 return -EINVAL; 3035 } 3036 3037 if (new_set_refcount) { 3038 new_set_refcount(new_refblock, new_refblock_index++, 3039 refcount); 3040 } else { 3041 new_refblock_index++; 3042 } 3043 new_refblock_empty = new_refblock_empty && refcount == 0; 3044 } 3045 3046 qcow2_cache_put(s->refcount_block_cache, &refblock); 3047 } else { 3048 /* No refblock means every refcount is 0 */ 3049 for (refblock_index = 0; refblock_index < s->refcount_block_size; 3050 refblock_index++) 3051 { 3052 if (new_refblock_index >= new_refblock_size) { 3053 /* new_refblock is now complete */ 3054 ret = operation(bs, new_reftable, *new_reftable_index, 3055 new_reftable_size, new_refblock, 3056 new_refblock_empty, allocated, errp); 3057 if (ret < 0) { 3058 return ret; 3059 } 3060 3061 (*new_reftable_index)++; 3062 new_refblock_index = 0; 3063 new_refblock_empty = true; 3064 } 3065 3066 if (new_set_refcount) { 3067 new_set_refcount(new_refblock, new_refblock_index++, 0); 3068 } else { 3069 new_refblock_index++; 3070 } 3071 } 3072 } 3073 } 3074 3075 if (new_refblock_index > 0) { 3076 /* Complete the potentially existing partially filled final refblock */ 3077 if (new_set_refcount) { 3078 for (; new_refblock_index < new_refblock_size; 3079 new_refblock_index++) 3080 { 3081 new_set_refcount(new_refblock, new_refblock_index, 0); 3082 } 3083 } 3084 3085 ret = operation(bs, new_reftable, *new_reftable_index, 3086 new_reftable_size, new_refblock, new_refblock_empty, 3087 allocated, errp); 3088 if (ret < 0) { 3089 return ret; 3090 } 3091 3092 (*new_reftable_index)++; 3093 } 3094 3095 status_cb(bs, (uint64_t)(index + 1) * s->refcount_table_size, 3096 (uint64_t)total * s->refcount_table_size, cb_opaque); 3097 3098 return 0; 3099 } 3100 3101 int qcow2_change_refcount_order(BlockDriverState *bs, int refcount_order, 3102 BlockDriverAmendStatusCB *status_cb, 3103 void *cb_opaque, Error **errp) 3104 { 3105 BDRVQcow2State *s = bs->opaque; 3106 Qcow2GetRefcountFunc *new_get_refcount; 3107 Qcow2SetRefcountFunc *new_set_refcount; 3108 void *new_refblock = qemu_blockalign(bs->file->bs, s->cluster_size); 3109 uint64_t *new_reftable = NULL, new_reftable_size = 0; 3110 uint64_t *old_reftable, old_reftable_size, old_reftable_offset; 3111 uint64_t new_reftable_index = 0; 3112 uint64_t i; 3113 int64_t new_reftable_offset = 0, allocated_reftable_size = 0; 3114 int new_refblock_size, new_refcount_bits = 1 << refcount_order; 3115 int old_refcount_order; 3116 int walk_index = 0; 3117 int ret; 3118 bool new_allocation; 3119 3120 assert(s->qcow_version >= 3); 3121 assert(refcount_order >= 0 && refcount_order <= 6); 3122 3123 /* see qcow2_open() */ 3124 new_refblock_size = 1 << (s->cluster_bits - (refcount_order - 3)); 3125 3126 new_get_refcount = get_refcount_funcs[refcount_order]; 3127 new_set_refcount = set_refcount_funcs[refcount_order]; 3128 3129 3130 do { 3131 int total_walks; 3132 3133 new_allocation = false; 3134 3135 /* At least we have to do this walk and the one which writes the 3136 * refblocks; also, at least we have to do this loop here at least 3137 * twice (normally), first to do the allocations, and second to 3138 * determine that everything is correctly allocated, this then makes 3139 * three walks in total */ 3140 total_walks = MAX(walk_index + 2, 3); 3141 3142 /* First, allocate the structures so they are present in the refcount 3143 * structures */ 3144 ret = walk_over_reftable(bs, &new_reftable, &new_reftable_index, 3145 &new_reftable_size, NULL, new_refblock_size, 3146 new_refcount_bits, &alloc_refblock, 3147 &new_allocation, NULL, status_cb, cb_opaque, 3148 walk_index++, total_walks, errp); 3149 if (ret < 0) { 3150 goto done; 3151 } 3152 3153 new_reftable_index = 0; 3154 3155 if (new_allocation) { 3156 if (new_reftable_offset) { 3157 qcow2_free_clusters(bs, new_reftable_offset, 3158 allocated_reftable_size * sizeof(uint64_t), 3159 QCOW2_DISCARD_NEVER); 3160 } 3161 3162 new_reftable_offset = qcow2_alloc_clusters(bs, new_reftable_size * 3163 sizeof(uint64_t)); 3164 if (new_reftable_offset < 0) { 3165 error_setg_errno(errp, -new_reftable_offset, 3166 "Failed to allocate the new reftable"); 3167 ret = new_reftable_offset; 3168 goto done; 3169 } 3170 allocated_reftable_size = new_reftable_size; 3171 } 3172 } while (new_allocation); 3173 3174 /* Second, write the new refblocks */ 3175 ret = walk_over_reftable(bs, &new_reftable, &new_reftable_index, 3176 &new_reftable_size, new_refblock, 3177 new_refblock_size, new_refcount_bits, 3178 &flush_refblock, &new_allocation, new_set_refcount, 3179 status_cb, cb_opaque, walk_index, walk_index + 1, 3180 errp); 3181 if (ret < 0) { 3182 goto done; 3183 } 3184 assert(!new_allocation); 3185 3186 3187 /* Write the new reftable */ 3188 ret = qcow2_pre_write_overlap_check(bs, 0, new_reftable_offset, 3189 new_reftable_size * sizeof(uint64_t), 3190 false); 3191 if (ret < 0) { 3192 error_setg_errno(errp, -ret, "Overlap check failed"); 3193 goto done; 3194 } 3195 3196 for (i = 0; i < new_reftable_size; i++) { 3197 cpu_to_be64s(&new_reftable[i]); 3198 } 3199 3200 ret = bdrv_pwrite(bs->file, new_reftable_offset, new_reftable, 3201 new_reftable_size * sizeof(uint64_t)); 3202 3203 for (i = 0; i < new_reftable_size; i++) { 3204 be64_to_cpus(&new_reftable[i]); 3205 } 3206 3207 if (ret < 0) { 3208 error_setg_errno(errp, -ret, "Failed to write the new reftable"); 3209 goto done; 3210 } 3211 3212 3213 /* Empty the refcount cache */ 3214 ret = qcow2_cache_flush(bs, s->refcount_block_cache); 3215 if (ret < 0) { 3216 error_setg_errno(errp, -ret, "Failed to flush the refblock cache"); 3217 goto done; 3218 } 3219 3220 /* Update the image header to point to the new reftable; this only updates 3221 * the fields which are relevant to qcow2_update_header(); other fields 3222 * such as s->refcount_table or s->refcount_bits stay stale for now 3223 * (because we have to restore everything if qcow2_update_header() fails) */ 3224 old_refcount_order = s->refcount_order; 3225 old_reftable_size = s->refcount_table_size; 3226 old_reftable_offset = s->refcount_table_offset; 3227 3228 s->refcount_order = refcount_order; 3229 s->refcount_table_size = new_reftable_size; 3230 s->refcount_table_offset = new_reftable_offset; 3231 3232 ret = qcow2_update_header(bs); 3233 if (ret < 0) { 3234 s->refcount_order = old_refcount_order; 3235 s->refcount_table_size = old_reftable_size; 3236 s->refcount_table_offset = old_reftable_offset; 3237 error_setg_errno(errp, -ret, "Failed to update the qcow2 header"); 3238 goto done; 3239 } 3240 3241 /* Now update the rest of the in-memory information */ 3242 old_reftable = s->refcount_table; 3243 s->refcount_table = new_reftable; 3244 update_max_refcount_table_index(s); 3245 3246 s->refcount_bits = 1 << refcount_order; 3247 s->refcount_max = UINT64_C(1) << (s->refcount_bits - 1); 3248 s->refcount_max += s->refcount_max - 1; 3249 3250 s->refcount_block_bits = s->cluster_bits - (refcount_order - 3); 3251 s->refcount_block_size = 1 << s->refcount_block_bits; 3252 3253 s->get_refcount = new_get_refcount; 3254 s->set_refcount = new_set_refcount; 3255 3256 /* For cleaning up all old refblocks and the old reftable below the "done" 3257 * label */ 3258 new_reftable = old_reftable; 3259 new_reftable_size = old_reftable_size; 3260 new_reftable_offset = old_reftable_offset; 3261 3262 done: 3263 if (new_reftable) { 3264 /* On success, new_reftable actually points to the old reftable (and 3265 * new_reftable_size is the old reftable's size); but that is just 3266 * fine */ 3267 for (i = 0; i < new_reftable_size; i++) { 3268 uint64_t offset = new_reftable[i] & REFT_OFFSET_MASK; 3269 if (offset) { 3270 qcow2_free_clusters(bs, offset, s->cluster_size, 3271 QCOW2_DISCARD_OTHER); 3272 } 3273 } 3274 g_free(new_reftable); 3275 3276 if (new_reftable_offset > 0) { 3277 qcow2_free_clusters(bs, new_reftable_offset, 3278 new_reftable_size * sizeof(uint64_t), 3279 QCOW2_DISCARD_OTHER); 3280 } 3281 } 3282 3283 qemu_vfree(new_refblock); 3284 return ret; 3285 } 3286 3287 static int64_t get_refblock_offset(BlockDriverState *bs, uint64_t offset) 3288 { 3289 BDRVQcow2State *s = bs->opaque; 3290 uint32_t index = offset_to_reftable_index(s, offset); 3291 int64_t covering_refblock_offset = 0; 3292 3293 if (index < s->refcount_table_size) { 3294 covering_refblock_offset = s->refcount_table[index] & REFT_OFFSET_MASK; 3295 } 3296 if (!covering_refblock_offset) { 3297 qcow2_signal_corruption(bs, true, -1, -1, "Refblock at %#" PRIx64 " is " 3298 "not covered by the refcount structures", 3299 offset); 3300 return -EIO; 3301 } 3302 3303 return covering_refblock_offset; 3304 } 3305 3306 static int qcow2_discard_refcount_block(BlockDriverState *bs, 3307 uint64_t discard_block_offs) 3308 { 3309 BDRVQcow2State *s = bs->opaque; 3310 int64_t refblock_offs; 3311 uint64_t cluster_index = discard_block_offs >> s->cluster_bits; 3312 uint32_t block_index = cluster_index & (s->refcount_block_size - 1); 3313 void *refblock; 3314 int ret; 3315 3316 refblock_offs = get_refblock_offset(bs, discard_block_offs); 3317 if (refblock_offs < 0) { 3318 return refblock_offs; 3319 } 3320 3321 assert(discard_block_offs != 0); 3322 3323 ret = qcow2_cache_get(bs, s->refcount_block_cache, refblock_offs, 3324 &refblock); 3325 if (ret < 0) { 3326 return ret; 3327 } 3328 3329 if (s->get_refcount(refblock, block_index) != 1) { 3330 qcow2_signal_corruption(bs, true, -1, -1, "Invalid refcount:" 3331 " refblock offset %#" PRIx64 3332 ", reftable index %u" 3333 ", block offset %#" PRIx64 3334 ", refcount %#" PRIx64, 3335 refblock_offs, 3336 offset_to_reftable_index(s, discard_block_offs), 3337 discard_block_offs, 3338 s->get_refcount(refblock, block_index)); 3339 qcow2_cache_put(s->refcount_block_cache, &refblock); 3340 return -EINVAL; 3341 } 3342 s->set_refcount(refblock, block_index, 0); 3343 3344 qcow2_cache_entry_mark_dirty(s->refcount_block_cache, refblock); 3345 3346 qcow2_cache_put(s->refcount_block_cache, &refblock); 3347 3348 if (cluster_index < s->free_cluster_index) { 3349 s->free_cluster_index = cluster_index; 3350 } 3351 3352 refblock = qcow2_cache_is_table_offset(s->refcount_block_cache, 3353 discard_block_offs); 3354 if (refblock) { 3355 /* discard refblock from the cache if refblock is cached */ 3356 qcow2_cache_discard(s->refcount_block_cache, refblock); 3357 } 3358 update_refcount_discard(bs, discard_block_offs, s->cluster_size); 3359 3360 return 0; 3361 } 3362 3363 int qcow2_shrink_reftable(BlockDriverState *bs) 3364 { 3365 BDRVQcow2State *s = bs->opaque; 3366 uint64_t *reftable_tmp = 3367 g_malloc(s->refcount_table_size * sizeof(uint64_t)); 3368 int i, ret; 3369 3370 for (i = 0; i < s->refcount_table_size; i++) { 3371 int64_t refblock_offs = s->refcount_table[i] & REFT_OFFSET_MASK; 3372 void *refblock; 3373 bool unused_block; 3374 3375 if (refblock_offs == 0) { 3376 reftable_tmp[i] = 0; 3377 continue; 3378 } 3379 ret = qcow2_cache_get(bs, s->refcount_block_cache, refblock_offs, 3380 &refblock); 3381 if (ret < 0) { 3382 goto out; 3383 } 3384 3385 /* the refblock has own reference */ 3386 if (i == offset_to_reftable_index(s, refblock_offs)) { 3387 uint64_t block_index = (refblock_offs >> s->cluster_bits) & 3388 (s->refcount_block_size - 1); 3389 uint64_t refcount = s->get_refcount(refblock, block_index); 3390 3391 s->set_refcount(refblock, block_index, 0); 3392 3393 unused_block = buffer_is_zero(refblock, s->cluster_size); 3394 3395 s->set_refcount(refblock, block_index, refcount); 3396 } else { 3397 unused_block = buffer_is_zero(refblock, s->cluster_size); 3398 } 3399 qcow2_cache_put(s->refcount_block_cache, &refblock); 3400 3401 reftable_tmp[i] = unused_block ? 0 : cpu_to_be64(s->refcount_table[i]); 3402 } 3403 3404 ret = bdrv_pwrite_sync(bs->file, s->refcount_table_offset, reftable_tmp, 3405 s->refcount_table_size * sizeof(uint64_t)); 3406 /* 3407 * If the write in the reftable failed the image may contain a partially 3408 * overwritten reftable. In this case it would be better to clear the 3409 * reftable in memory to avoid possible image corruption. 3410 */ 3411 for (i = 0; i < s->refcount_table_size; i++) { 3412 if (s->refcount_table[i] && !reftable_tmp[i]) { 3413 if (ret == 0) { 3414 ret = qcow2_discard_refcount_block(bs, s->refcount_table[i] & 3415 REFT_OFFSET_MASK); 3416 } 3417 s->refcount_table[i] = 0; 3418 } 3419 } 3420 3421 if (!s->cache_discards) { 3422 qcow2_process_discards(bs, ret); 3423 } 3424 3425 out: 3426 g_free(reftable_tmp); 3427 return ret; 3428 } 3429 3430 int64_t qcow2_get_last_cluster(BlockDriverState *bs, int64_t size) 3431 { 3432 BDRVQcow2State *s = bs->opaque; 3433 int64_t i; 3434 3435 for (i = size_to_clusters(s, size) - 1; i >= 0; i--) { 3436 uint64_t refcount; 3437 int ret = qcow2_get_refcount(bs, i, &refcount); 3438 if (ret < 0) { 3439 fprintf(stderr, "Can't get refcount for cluster %" PRId64 ": %s\n", 3440 i, strerror(-ret)); 3441 return ret; 3442 } 3443 if (refcount > 0) { 3444 return i; 3445 } 3446 } 3447 qcow2_signal_corruption(bs, true, -1, -1, 3448 "There are no references in the refcount table."); 3449 return -EIO; 3450 } 3451 3452 int qcow2_detect_metadata_preallocation(BlockDriverState *bs) 3453 { 3454 BDRVQcow2State *s = bs->opaque; 3455 int64_t i, end_cluster, cluster_count = 0, threshold; 3456 int64_t file_length, real_allocation, real_clusters; 3457 3458 qemu_co_mutex_assert_locked(&s->lock); 3459 3460 file_length = bdrv_getlength(bs->file->bs); 3461 if (file_length < 0) { 3462 return file_length; 3463 } 3464 3465 real_allocation = bdrv_get_allocated_file_size(bs->file->bs); 3466 if (real_allocation < 0) { 3467 return real_allocation; 3468 } 3469 3470 real_clusters = real_allocation / s->cluster_size; 3471 threshold = MAX(real_clusters * 10 / 9, real_clusters + 2); 3472 3473 end_cluster = size_to_clusters(s, file_length); 3474 for (i = 0; i < end_cluster && cluster_count < threshold; i++) { 3475 uint64_t refcount; 3476 int ret = qcow2_get_refcount(bs, i, &refcount); 3477 if (ret < 0) { 3478 return ret; 3479 } 3480 cluster_count += !!refcount; 3481 } 3482 3483 return cluster_count >= threshold; 3484 } 3485