rtl8139: fix possible out of bound access
[qemu/ar7.git] / block / qcow2-cluster.c
blobd37fe08b3d514424d51f3c8febb449808a2d3e18
1 /*
2 * Block driver for the QCOW version 2 format
4 * Copyright (c) 2004-2006 Fabrice Bellard
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:
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
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.
25 #include "qemu/osdep.h"
26 #include <zlib.h>
28 #include "qapi/error.h"
29 #include "qemu-common.h"
30 #include "block/block_int.h"
31 #include "qcow2.h"
32 #include "qemu/bswap.h"
33 #include "trace.h"
35 int qcow2_shrink_l1_table(BlockDriverState *bs, uint64_t exact_size)
37 BDRVQcow2State *s = bs->opaque;
38 int new_l1_size, i, ret;
40 if (exact_size >= s->l1_size) {
41 return 0;
44 new_l1_size = exact_size;
46 #ifdef DEBUG_ALLOC2
47 fprintf(stderr, "shrink l1_table from %d to %d\n", s->l1_size, new_l1_size);
48 #endif
50 BLKDBG_EVENT(bs->file, BLKDBG_L1_SHRINK_WRITE_TABLE);
51 ret = bdrv_pwrite_zeroes(bs->file, s->l1_table_offset +
52 new_l1_size * sizeof(uint64_t),
53 (s->l1_size - new_l1_size) * sizeof(uint64_t), 0);
54 if (ret < 0) {
55 goto fail;
58 ret = bdrv_flush(bs->file->bs);
59 if (ret < 0) {
60 goto fail;
63 BLKDBG_EVENT(bs->file, BLKDBG_L1_SHRINK_FREE_L2_CLUSTERS);
64 for (i = s->l1_size - 1; i > new_l1_size - 1; i--) {
65 if ((s->l1_table[i] & L1E_OFFSET_MASK) == 0) {
66 continue;
68 qcow2_free_clusters(bs, s->l1_table[i] & L1E_OFFSET_MASK,
69 s->cluster_size, QCOW2_DISCARD_ALWAYS);
70 s->l1_table[i] = 0;
72 return 0;
74 fail:
76 * If the write in the l1_table failed the image may contain a partially
77 * overwritten l1_table. In this case it would be better to clear the
78 * l1_table in memory to avoid possible image corruption.
80 memset(s->l1_table + new_l1_size, 0,
81 (s->l1_size - new_l1_size) * sizeof(uint64_t));
82 return ret;
85 int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size,
86 bool exact_size)
88 BDRVQcow2State *s = bs->opaque;
89 int new_l1_size2, ret, i;
90 uint64_t *new_l1_table;
91 int64_t old_l1_table_offset, old_l1_size;
92 int64_t new_l1_table_offset, new_l1_size;
93 uint8_t data[12];
95 if (min_size <= s->l1_size)
96 return 0;
98 /* Do a sanity check on min_size before trying to calculate new_l1_size
99 * (this prevents overflows during the while loop for the calculation of
100 * new_l1_size) */
101 if (min_size > INT_MAX / sizeof(uint64_t)) {
102 return -EFBIG;
105 if (exact_size) {
106 new_l1_size = min_size;
107 } else {
108 /* Bump size up to reduce the number of times we have to grow */
109 new_l1_size = s->l1_size;
110 if (new_l1_size == 0) {
111 new_l1_size = 1;
113 while (min_size > new_l1_size) {
114 new_l1_size = DIV_ROUND_UP(new_l1_size * 3, 2);
118 QEMU_BUILD_BUG_ON(QCOW_MAX_L1_SIZE > INT_MAX);
119 if (new_l1_size > QCOW_MAX_L1_SIZE / sizeof(uint64_t)) {
120 return -EFBIG;
123 #ifdef DEBUG_ALLOC2
124 fprintf(stderr, "grow l1_table from %d to %" PRId64 "\n",
125 s->l1_size, new_l1_size);
126 #endif
128 new_l1_size2 = sizeof(uint64_t) * new_l1_size;
129 new_l1_table = qemu_try_blockalign(bs->file->bs,
130 ROUND_UP(new_l1_size2, 512));
131 if (new_l1_table == NULL) {
132 return -ENOMEM;
134 memset(new_l1_table, 0, ROUND_UP(new_l1_size2, 512));
136 if (s->l1_size) {
137 memcpy(new_l1_table, s->l1_table, s->l1_size * sizeof(uint64_t));
140 /* write new table (align to cluster) */
141 BLKDBG_EVENT(bs->file, BLKDBG_L1_GROW_ALLOC_TABLE);
142 new_l1_table_offset = qcow2_alloc_clusters(bs, new_l1_size2);
143 if (new_l1_table_offset < 0) {
144 qemu_vfree(new_l1_table);
145 return new_l1_table_offset;
148 ret = qcow2_cache_flush(bs, s->refcount_block_cache);
149 if (ret < 0) {
150 goto fail;
153 /* the L1 position has not yet been updated, so these clusters must
154 * indeed be completely free */
155 ret = qcow2_pre_write_overlap_check(bs, 0, new_l1_table_offset,
156 new_l1_size2);
157 if (ret < 0) {
158 goto fail;
161 BLKDBG_EVENT(bs->file, BLKDBG_L1_GROW_WRITE_TABLE);
162 for(i = 0; i < s->l1_size; i++)
163 new_l1_table[i] = cpu_to_be64(new_l1_table[i]);
164 ret = bdrv_pwrite_sync(bs->file, new_l1_table_offset,
165 new_l1_table, new_l1_size2);
166 if (ret < 0)
167 goto fail;
168 for(i = 0; i < s->l1_size; i++)
169 new_l1_table[i] = be64_to_cpu(new_l1_table[i]);
171 /* set new table */
172 BLKDBG_EVENT(bs->file, BLKDBG_L1_GROW_ACTIVATE_TABLE);
173 stl_be_p(data, new_l1_size);
174 stq_be_p(data + 4, new_l1_table_offset);
175 ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, l1_size),
176 data, sizeof(data));
177 if (ret < 0) {
178 goto fail;
180 qemu_vfree(s->l1_table);
181 old_l1_table_offset = s->l1_table_offset;
182 s->l1_table_offset = new_l1_table_offset;
183 s->l1_table = new_l1_table;
184 old_l1_size = s->l1_size;
185 s->l1_size = new_l1_size;
186 qcow2_free_clusters(bs, old_l1_table_offset, old_l1_size * sizeof(uint64_t),
187 QCOW2_DISCARD_OTHER);
188 return 0;
189 fail:
190 qemu_vfree(new_l1_table);
191 qcow2_free_clusters(bs, new_l1_table_offset, new_l1_size2,
192 QCOW2_DISCARD_OTHER);
193 return ret;
197 * l2_load
199 * @bs: The BlockDriverState
200 * @offset: A guest offset, used to calculate what slice of the L2
201 * table to load.
202 * @l2_offset: Offset to the L2 table in the image file.
203 * @l2_slice: Location to store the pointer to the L2 slice.
205 * Loads a L2 slice into memory (L2 slices are the parts of L2 tables
206 * that are loaded by the qcow2 cache). If the slice is in the cache,
207 * the cache is used; otherwise the L2 slice is loaded from the image
208 * file.
210 static int l2_load(BlockDriverState *bs, uint64_t offset,
211 uint64_t l2_offset, uint64_t **l2_slice)
213 BDRVQcow2State *s = bs->opaque;
214 int start_of_slice = sizeof(uint64_t) *
215 (offset_to_l2_index(s, offset) - offset_to_l2_slice_index(s, offset));
217 return qcow2_cache_get(bs, s->l2_table_cache, l2_offset + start_of_slice,
218 (void **)l2_slice);
222 * Writes one sector of the L1 table to the disk (can't update single entries
223 * and we really don't want bdrv_pread to perform a read-modify-write)
225 #define L1_ENTRIES_PER_SECTOR (512 / 8)
226 int qcow2_write_l1_entry(BlockDriverState *bs, int l1_index)
228 BDRVQcow2State *s = bs->opaque;
229 uint64_t buf[L1_ENTRIES_PER_SECTOR] = { 0 };
230 int l1_start_index;
231 int i, ret;
233 l1_start_index = l1_index & ~(L1_ENTRIES_PER_SECTOR - 1);
234 for (i = 0; i < L1_ENTRIES_PER_SECTOR && l1_start_index + i < s->l1_size;
235 i++)
237 buf[i] = cpu_to_be64(s->l1_table[l1_start_index + i]);
240 ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_ACTIVE_L1,
241 s->l1_table_offset + 8 * l1_start_index, sizeof(buf));
242 if (ret < 0) {
243 return ret;
246 BLKDBG_EVENT(bs->file, BLKDBG_L1_UPDATE);
247 ret = bdrv_pwrite_sync(bs->file,
248 s->l1_table_offset + 8 * l1_start_index,
249 buf, sizeof(buf));
250 if (ret < 0) {
251 return ret;
254 return 0;
258 * l2_allocate
260 * Allocate a new l2 entry in the file. If l1_index points to an already
261 * used entry in the L2 table (i.e. we are doing a copy on write for the L2
262 * table) copy the contents of the old L2 table into the newly allocated one.
263 * Otherwise the new table is initialized with zeros.
267 static int l2_allocate(BlockDriverState *bs, int l1_index)
269 BDRVQcow2State *s = bs->opaque;
270 uint64_t old_l2_offset;
271 uint64_t *l2_slice = NULL;
272 unsigned slice, slice_size2, n_slices;
273 int64_t l2_offset;
274 int ret;
276 old_l2_offset = s->l1_table[l1_index];
278 trace_qcow2_l2_allocate(bs, l1_index);
280 /* allocate a new l2 entry */
282 l2_offset = qcow2_alloc_clusters(bs, s->l2_size * sizeof(uint64_t));
283 if (l2_offset < 0) {
284 ret = l2_offset;
285 goto fail;
288 /* If we're allocating the table at offset 0 then something is wrong */
289 if (l2_offset == 0) {
290 qcow2_signal_corruption(bs, true, -1, -1, "Preventing invalid "
291 "allocation of L2 table at offset 0");
292 ret = -EIO;
293 goto fail;
296 ret = qcow2_cache_flush(bs, s->refcount_block_cache);
297 if (ret < 0) {
298 goto fail;
301 /* allocate a new entry in the l2 cache */
303 slice_size2 = s->l2_slice_size * sizeof(uint64_t);
304 n_slices = s->cluster_size / slice_size2;
306 trace_qcow2_l2_allocate_get_empty(bs, l1_index);
307 for (slice = 0; slice < n_slices; slice++) {
308 ret = qcow2_cache_get_empty(bs, s->l2_table_cache,
309 l2_offset + slice * slice_size2,
310 (void **) &l2_slice);
311 if (ret < 0) {
312 goto fail;
315 if ((old_l2_offset & L1E_OFFSET_MASK) == 0) {
316 /* if there was no old l2 table, clear the new slice */
317 memset(l2_slice, 0, slice_size2);
318 } else {
319 uint64_t *old_slice;
320 uint64_t old_l2_slice_offset =
321 (old_l2_offset & L1E_OFFSET_MASK) + slice * slice_size2;
323 /* if there was an old l2 table, read a slice from the disk */
324 BLKDBG_EVENT(bs->file, BLKDBG_L2_ALLOC_COW_READ);
325 ret = qcow2_cache_get(bs, s->l2_table_cache, old_l2_slice_offset,
326 (void **) &old_slice);
327 if (ret < 0) {
328 goto fail;
331 memcpy(l2_slice, old_slice, slice_size2);
333 qcow2_cache_put(s->l2_table_cache, (void **) &old_slice);
336 /* write the l2 slice to the file */
337 BLKDBG_EVENT(bs->file, BLKDBG_L2_ALLOC_WRITE);
339 trace_qcow2_l2_allocate_write_l2(bs, l1_index);
340 qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice);
341 qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
344 ret = qcow2_cache_flush(bs, s->l2_table_cache);
345 if (ret < 0) {
346 goto fail;
349 /* update the L1 entry */
350 trace_qcow2_l2_allocate_write_l1(bs, l1_index);
351 s->l1_table[l1_index] = l2_offset | QCOW_OFLAG_COPIED;
352 ret = qcow2_write_l1_entry(bs, l1_index);
353 if (ret < 0) {
354 goto fail;
357 trace_qcow2_l2_allocate_done(bs, l1_index, 0);
358 return 0;
360 fail:
361 trace_qcow2_l2_allocate_done(bs, l1_index, ret);
362 if (l2_slice != NULL) {
363 qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
365 s->l1_table[l1_index] = old_l2_offset;
366 if (l2_offset > 0) {
367 qcow2_free_clusters(bs, l2_offset, s->l2_size * sizeof(uint64_t),
368 QCOW2_DISCARD_ALWAYS);
370 return ret;
374 * Checks how many clusters in a given L2 slice are contiguous in the image
375 * file. As soon as one of the flags in the bitmask stop_flags changes compared
376 * to the first cluster, the search is stopped and the cluster is not counted
377 * as contiguous. (This allows it, for example, to stop at the first compressed
378 * cluster which may require a different handling)
380 static int count_contiguous_clusters(int nb_clusters, int cluster_size,
381 uint64_t *l2_slice, uint64_t stop_flags)
383 int i;
384 QCow2ClusterType first_cluster_type;
385 uint64_t mask = stop_flags | L2E_OFFSET_MASK | QCOW_OFLAG_COMPRESSED;
386 uint64_t first_entry = be64_to_cpu(l2_slice[0]);
387 uint64_t offset = first_entry & mask;
389 if (!offset) {
390 return 0;
393 /* must be allocated */
394 first_cluster_type = qcow2_get_cluster_type(first_entry);
395 assert(first_cluster_type == QCOW2_CLUSTER_NORMAL ||
396 first_cluster_type == QCOW2_CLUSTER_ZERO_ALLOC);
398 for (i = 0; i < nb_clusters; i++) {
399 uint64_t l2_entry = be64_to_cpu(l2_slice[i]) & mask;
400 if (offset + (uint64_t) i * cluster_size != l2_entry) {
401 break;
405 return i;
409 * Checks how many consecutive unallocated clusters in a given L2
410 * slice have the same cluster type.
412 static int count_contiguous_clusters_unallocated(int nb_clusters,
413 uint64_t *l2_slice,
414 QCow2ClusterType wanted_type)
416 int i;
418 assert(wanted_type == QCOW2_CLUSTER_ZERO_PLAIN ||
419 wanted_type == QCOW2_CLUSTER_UNALLOCATED);
420 for (i = 0; i < nb_clusters; i++) {
421 uint64_t entry = be64_to_cpu(l2_slice[i]);
422 QCow2ClusterType type = qcow2_get_cluster_type(entry);
424 if (type != wanted_type) {
425 break;
429 return i;
432 static int coroutine_fn do_perform_cow_read(BlockDriverState *bs,
433 uint64_t src_cluster_offset,
434 unsigned offset_in_cluster,
435 QEMUIOVector *qiov)
437 int ret;
439 if (qiov->size == 0) {
440 return 0;
443 BLKDBG_EVENT(bs->file, BLKDBG_COW_READ);
445 if (!bs->drv) {
446 return -ENOMEDIUM;
449 /* Call .bdrv_co_readv() directly instead of using the public block-layer
450 * interface. This avoids double I/O throttling and request tracking,
451 * which can lead to deadlock when block layer copy-on-read is enabled.
453 ret = bs->drv->bdrv_co_preadv(bs, src_cluster_offset + offset_in_cluster,
454 qiov->size, qiov, 0);
455 if (ret < 0) {
456 return ret;
459 return 0;
462 static bool coroutine_fn do_perform_cow_encrypt(BlockDriverState *bs,
463 uint64_t src_cluster_offset,
464 uint64_t cluster_offset,
465 unsigned offset_in_cluster,
466 uint8_t *buffer,
467 unsigned bytes)
469 if (bytes && bs->encrypted) {
470 BDRVQcow2State *s = bs->opaque;
471 int64_t offset = (s->crypt_physical_offset ?
472 (cluster_offset + offset_in_cluster) :
473 (src_cluster_offset + offset_in_cluster));
474 assert((offset_in_cluster & ~BDRV_SECTOR_MASK) == 0);
475 assert((bytes & ~BDRV_SECTOR_MASK) == 0);
476 assert(s->crypto);
477 if (qcrypto_block_encrypt(s->crypto, offset, buffer, bytes, NULL) < 0) {
478 return false;
481 return true;
484 static int coroutine_fn do_perform_cow_write(BlockDriverState *bs,
485 uint64_t cluster_offset,
486 unsigned offset_in_cluster,
487 QEMUIOVector *qiov)
489 int ret;
491 if (qiov->size == 0) {
492 return 0;
495 ret = qcow2_pre_write_overlap_check(bs, 0,
496 cluster_offset + offset_in_cluster, qiov->size);
497 if (ret < 0) {
498 return ret;
501 BLKDBG_EVENT(bs->file, BLKDBG_COW_WRITE);
502 ret = bdrv_co_pwritev(bs->file, cluster_offset + offset_in_cluster,
503 qiov->size, qiov, 0);
504 if (ret < 0) {
505 return ret;
508 return 0;
513 * get_cluster_offset
515 * For a given offset of the virtual disk, find the cluster type and offset in
516 * the qcow2 file. The offset is stored in *cluster_offset.
518 * On entry, *bytes is the maximum number of contiguous bytes starting at
519 * offset that we are interested in.
521 * On exit, *bytes is the number of bytes starting at offset that have the same
522 * cluster type and (if applicable) are stored contiguously in the image file.
523 * Compressed clusters are always returned one by one.
525 * Returns the cluster type (QCOW2_CLUSTER_*) on success, -errno in error
526 * cases.
528 int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset,
529 unsigned int *bytes, uint64_t *cluster_offset)
531 BDRVQcow2State *s = bs->opaque;
532 unsigned int l2_index;
533 uint64_t l1_index, l2_offset, *l2_slice;
534 int c;
535 unsigned int offset_in_cluster;
536 uint64_t bytes_available, bytes_needed, nb_clusters;
537 QCow2ClusterType type;
538 int ret;
540 offset_in_cluster = offset_into_cluster(s, offset);
541 bytes_needed = (uint64_t) *bytes + offset_in_cluster;
543 /* compute how many bytes there are between the start of the cluster
544 * containing offset and the end of the l2 slice that contains
545 * the entry pointing to it */
546 bytes_available =
547 ((uint64_t) (s->l2_slice_size - offset_to_l2_slice_index(s, offset)))
548 << s->cluster_bits;
550 if (bytes_needed > bytes_available) {
551 bytes_needed = bytes_available;
554 *cluster_offset = 0;
556 /* seek to the l2 offset in the l1 table */
558 l1_index = offset_to_l1_index(s, offset);
559 if (l1_index >= s->l1_size) {
560 type = QCOW2_CLUSTER_UNALLOCATED;
561 goto out;
564 l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK;
565 if (!l2_offset) {
566 type = QCOW2_CLUSTER_UNALLOCATED;
567 goto out;
570 if (offset_into_cluster(s, l2_offset)) {
571 qcow2_signal_corruption(bs, true, -1, -1, "L2 table offset %#" PRIx64
572 " unaligned (L1 index: %#" PRIx64 ")",
573 l2_offset, l1_index);
574 return -EIO;
577 /* load the l2 slice in memory */
579 ret = l2_load(bs, offset, l2_offset, &l2_slice);
580 if (ret < 0) {
581 return ret;
584 /* find the cluster offset for the given disk offset */
586 l2_index = offset_to_l2_slice_index(s, offset);
587 *cluster_offset = be64_to_cpu(l2_slice[l2_index]);
589 nb_clusters = size_to_clusters(s, bytes_needed);
590 /* bytes_needed <= *bytes + offset_in_cluster, both of which are unsigned
591 * integers; the minimum cluster size is 512, so this assertion is always
592 * true */
593 assert(nb_clusters <= INT_MAX);
595 type = qcow2_get_cluster_type(*cluster_offset);
596 if (s->qcow_version < 3 && (type == QCOW2_CLUSTER_ZERO_PLAIN ||
597 type == QCOW2_CLUSTER_ZERO_ALLOC)) {
598 qcow2_signal_corruption(bs, true, -1, -1, "Zero cluster entry found"
599 " in pre-v3 image (L2 offset: %#" PRIx64
600 ", L2 index: %#x)", l2_offset, l2_index);
601 ret = -EIO;
602 goto fail;
604 switch (type) {
605 case QCOW2_CLUSTER_COMPRESSED:
606 /* Compressed clusters can only be processed one by one */
607 c = 1;
608 *cluster_offset &= L2E_COMPRESSED_OFFSET_SIZE_MASK;
609 break;
610 case QCOW2_CLUSTER_ZERO_PLAIN:
611 case QCOW2_CLUSTER_UNALLOCATED:
612 /* how many empty clusters ? */
613 c = count_contiguous_clusters_unallocated(nb_clusters,
614 &l2_slice[l2_index], type);
615 *cluster_offset = 0;
616 break;
617 case QCOW2_CLUSTER_ZERO_ALLOC:
618 case QCOW2_CLUSTER_NORMAL:
619 /* how many allocated clusters ? */
620 c = count_contiguous_clusters(nb_clusters, s->cluster_size,
621 &l2_slice[l2_index], QCOW_OFLAG_ZERO);
622 *cluster_offset &= L2E_OFFSET_MASK;
623 if (offset_into_cluster(s, *cluster_offset)) {
624 qcow2_signal_corruption(bs, true, -1, -1,
625 "Cluster allocation offset %#"
626 PRIx64 " unaligned (L2 offset: %#" PRIx64
627 ", L2 index: %#x)", *cluster_offset,
628 l2_offset, l2_index);
629 ret = -EIO;
630 goto fail;
632 break;
633 default:
634 abort();
637 qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
639 bytes_available = (int64_t)c * s->cluster_size;
641 out:
642 if (bytes_available > bytes_needed) {
643 bytes_available = bytes_needed;
646 /* bytes_available <= bytes_needed <= *bytes + offset_in_cluster;
647 * subtracting offset_in_cluster will therefore definitely yield something
648 * not exceeding UINT_MAX */
649 assert(bytes_available - offset_in_cluster <= UINT_MAX);
650 *bytes = bytes_available - offset_in_cluster;
652 return type;
654 fail:
655 qcow2_cache_put(s->l2_table_cache, (void **)&l2_slice);
656 return ret;
660 * get_cluster_table
662 * for a given disk offset, load (and allocate if needed)
663 * the appropriate slice of its l2 table.
665 * the cluster index in the l2 slice is given to the caller.
667 * Returns 0 on success, -errno in failure case
669 static int get_cluster_table(BlockDriverState *bs, uint64_t offset,
670 uint64_t **new_l2_slice,
671 int *new_l2_index)
673 BDRVQcow2State *s = bs->opaque;
674 unsigned int l2_index;
675 uint64_t l1_index, l2_offset;
676 uint64_t *l2_slice = NULL;
677 int ret;
679 /* seek to the l2 offset in the l1 table */
681 l1_index = offset_to_l1_index(s, offset);
682 if (l1_index >= s->l1_size) {
683 ret = qcow2_grow_l1_table(bs, l1_index + 1, false);
684 if (ret < 0) {
685 return ret;
689 assert(l1_index < s->l1_size);
690 l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK;
691 if (offset_into_cluster(s, l2_offset)) {
692 qcow2_signal_corruption(bs, true, -1, -1, "L2 table offset %#" PRIx64
693 " unaligned (L1 index: %#" PRIx64 ")",
694 l2_offset, l1_index);
695 return -EIO;
698 if (!(s->l1_table[l1_index] & QCOW_OFLAG_COPIED)) {
699 /* First allocate a new L2 table (and do COW if needed) */
700 ret = l2_allocate(bs, l1_index);
701 if (ret < 0) {
702 return ret;
705 /* Then decrease the refcount of the old table */
706 if (l2_offset) {
707 qcow2_free_clusters(bs, l2_offset, s->l2_size * sizeof(uint64_t),
708 QCOW2_DISCARD_OTHER);
711 /* Get the offset of the newly-allocated l2 table */
712 l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK;
713 assert(offset_into_cluster(s, l2_offset) == 0);
716 /* load the l2 slice in memory */
717 ret = l2_load(bs, offset, l2_offset, &l2_slice);
718 if (ret < 0) {
719 return ret;
722 /* find the cluster offset for the given disk offset */
724 l2_index = offset_to_l2_slice_index(s, offset);
726 *new_l2_slice = l2_slice;
727 *new_l2_index = l2_index;
729 return 0;
733 * alloc_compressed_cluster_offset
735 * For a given offset of the disk image, return cluster offset in
736 * qcow2 file.
738 * If the offset is not found, allocate a new compressed cluster.
740 * Return the cluster offset if successful,
741 * Return 0, otherwise.
745 uint64_t qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs,
746 uint64_t offset,
747 int compressed_size)
749 BDRVQcow2State *s = bs->opaque;
750 int l2_index, ret;
751 uint64_t *l2_slice;
752 int64_t cluster_offset;
753 int nb_csectors;
755 ret = get_cluster_table(bs, offset, &l2_slice, &l2_index);
756 if (ret < 0) {
757 return 0;
760 /* Compression can't overwrite anything. Fail if the cluster was already
761 * allocated. */
762 cluster_offset = be64_to_cpu(l2_slice[l2_index]);
763 if (cluster_offset & L2E_OFFSET_MASK) {
764 qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
765 return 0;
768 cluster_offset = qcow2_alloc_bytes(bs, compressed_size);
769 if (cluster_offset < 0) {
770 qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
771 return 0;
774 nb_csectors = ((cluster_offset + compressed_size - 1) >> 9) -
775 (cluster_offset >> 9);
777 cluster_offset |= QCOW_OFLAG_COMPRESSED |
778 ((uint64_t)nb_csectors << s->csize_shift);
780 /* update L2 table */
782 /* compressed clusters never have the copied flag */
784 BLKDBG_EVENT(bs->file, BLKDBG_L2_UPDATE_COMPRESSED);
785 qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice);
786 l2_slice[l2_index] = cpu_to_be64(cluster_offset);
787 qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
789 return cluster_offset;
792 static int perform_cow(BlockDriverState *bs, QCowL2Meta *m)
794 BDRVQcow2State *s = bs->opaque;
795 Qcow2COWRegion *start = &m->cow_start;
796 Qcow2COWRegion *end = &m->cow_end;
797 unsigned buffer_size;
798 unsigned data_bytes = end->offset - (start->offset + start->nb_bytes);
799 bool merge_reads;
800 uint8_t *start_buffer, *end_buffer;
801 QEMUIOVector qiov;
802 int ret;
804 assert(start->nb_bytes <= UINT_MAX - end->nb_bytes);
805 assert(start->nb_bytes + end->nb_bytes <= UINT_MAX - data_bytes);
806 assert(start->offset + start->nb_bytes <= end->offset);
807 assert(!m->data_qiov || m->data_qiov->size == data_bytes);
809 if (start->nb_bytes == 0 && end->nb_bytes == 0) {
810 return 0;
813 /* If we have to read both the start and end COW regions and the
814 * middle region is not too large then perform just one read
815 * operation */
816 merge_reads = start->nb_bytes && end->nb_bytes && data_bytes <= 16384;
817 if (merge_reads) {
818 buffer_size = start->nb_bytes + data_bytes + end->nb_bytes;
819 } else {
820 /* If we have to do two reads, add some padding in the middle
821 * if necessary to make sure that the end region is optimally
822 * aligned. */
823 size_t align = bdrv_opt_mem_align(bs);
824 assert(align > 0 && align <= UINT_MAX);
825 assert(QEMU_ALIGN_UP(start->nb_bytes, align) <=
826 UINT_MAX - end->nb_bytes);
827 buffer_size = QEMU_ALIGN_UP(start->nb_bytes, align) + end->nb_bytes;
830 /* Reserve a buffer large enough to store all the data that we're
831 * going to read */
832 start_buffer = qemu_try_blockalign(bs, buffer_size);
833 if (start_buffer == NULL) {
834 return -ENOMEM;
836 /* The part of the buffer where the end region is located */
837 end_buffer = start_buffer + buffer_size - end->nb_bytes;
839 qemu_iovec_init(&qiov, 2 + (m->data_qiov ? m->data_qiov->niov : 0));
841 qemu_co_mutex_unlock(&s->lock);
842 /* First we read the existing data from both COW regions. We
843 * either read the whole region in one go, or the start and end
844 * regions separately. */
845 if (merge_reads) {
846 qemu_iovec_add(&qiov, start_buffer, buffer_size);
847 ret = do_perform_cow_read(bs, m->offset, start->offset, &qiov);
848 } else {
849 qemu_iovec_add(&qiov, start_buffer, start->nb_bytes);
850 ret = do_perform_cow_read(bs, m->offset, start->offset, &qiov);
851 if (ret < 0) {
852 goto fail;
855 qemu_iovec_reset(&qiov);
856 qemu_iovec_add(&qiov, end_buffer, end->nb_bytes);
857 ret = do_perform_cow_read(bs, m->offset, end->offset, &qiov);
859 if (ret < 0) {
860 goto fail;
863 /* Encrypt the data if necessary before writing it */
864 if (bs->encrypted) {
865 if (!do_perform_cow_encrypt(bs, m->offset, m->alloc_offset,
866 start->offset, start_buffer,
867 start->nb_bytes) ||
868 !do_perform_cow_encrypt(bs, m->offset, m->alloc_offset,
869 end->offset, end_buffer, end->nb_bytes)) {
870 ret = -EIO;
871 goto fail;
875 /* And now we can write everything. If we have the guest data we
876 * can write everything in one single operation */
877 if (m->data_qiov) {
878 qemu_iovec_reset(&qiov);
879 if (start->nb_bytes) {
880 qemu_iovec_add(&qiov, start_buffer, start->nb_bytes);
882 qemu_iovec_concat(&qiov, m->data_qiov, 0, data_bytes);
883 if (end->nb_bytes) {
884 qemu_iovec_add(&qiov, end_buffer, end->nb_bytes);
886 /* NOTE: we have a write_aio blkdebug event here followed by
887 * a cow_write one in do_perform_cow_write(), but there's only
888 * one single I/O operation */
889 BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO);
890 ret = do_perform_cow_write(bs, m->alloc_offset, start->offset, &qiov);
891 } else {
892 /* If there's no guest data then write both COW regions separately */
893 qemu_iovec_reset(&qiov);
894 qemu_iovec_add(&qiov, start_buffer, start->nb_bytes);
895 ret = do_perform_cow_write(bs, m->alloc_offset, start->offset, &qiov);
896 if (ret < 0) {
897 goto fail;
900 qemu_iovec_reset(&qiov);
901 qemu_iovec_add(&qiov, end_buffer, end->nb_bytes);
902 ret = do_perform_cow_write(bs, m->alloc_offset, end->offset, &qiov);
905 fail:
906 qemu_co_mutex_lock(&s->lock);
909 * Before we update the L2 table to actually point to the new cluster, we
910 * need to be sure that the refcounts have been increased and COW was
911 * handled.
913 if (ret == 0) {
914 qcow2_cache_depends_on_flush(s->l2_table_cache);
917 qemu_vfree(start_buffer);
918 qemu_iovec_destroy(&qiov);
919 return ret;
922 int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m)
924 BDRVQcow2State *s = bs->opaque;
925 int i, j = 0, l2_index, ret;
926 uint64_t *old_cluster, *l2_slice;
927 uint64_t cluster_offset = m->alloc_offset;
929 trace_qcow2_cluster_link_l2(qemu_coroutine_self(), m->nb_clusters);
930 assert(m->nb_clusters > 0);
932 old_cluster = g_try_new(uint64_t, m->nb_clusters);
933 if (old_cluster == NULL) {
934 ret = -ENOMEM;
935 goto err;
938 /* copy content of unmodified sectors */
939 ret = perform_cow(bs, m);
940 if (ret < 0) {
941 goto err;
944 /* Update L2 table. */
945 if (s->use_lazy_refcounts) {
946 qcow2_mark_dirty(bs);
948 if (qcow2_need_accurate_refcounts(s)) {
949 qcow2_cache_set_dependency(bs, s->l2_table_cache,
950 s->refcount_block_cache);
953 ret = get_cluster_table(bs, m->offset, &l2_slice, &l2_index);
954 if (ret < 0) {
955 goto err;
957 qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice);
959 assert(l2_index + m->nb_clusters <= s->l2_slice_size);
960 for (i = 0; i < m->nb_clusters; i++) {
961 /* if two concurrent writes happen to the same unallocated cluster
962 * each write allocates separate cluster and writes data concurrently.
963 * The first one to complete updates l2 table with pointer to its
964 * cluster the second one has to do RMW (which is done above by
965 * perform_cow()), update l2 table with its cluster pointer and free
966 * old cluster. This is what this loop does */
967 if (l2_slice[l2_index + i] != 0) {
968 old_cluster[j++] = l2_slice[l2_index + i];
971 l2_slice[l2_index + i] = cpu_to_be64((cluster_offset +
972 (i << s->cluster_bits)) | QCOW_OFLAG_COPIED);
976 qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
979 * If this was a COW, we need to decrease the refcount of the old cluster.
981 * Don't discard clusters that reach a refcount of 0 (e.g. compressed
982 * clusters), the next write will reuse them anyway.
984 if (!m->keep_old_clusters && j != 0) {
985 for (i = 0; i < j; i++) {
986 qcow2_free_any_clusters(bs, be64_to_cpu(old_cluster[i]), 1,
987 QCOW2_DISCARD_NEVER);
991 ret = 0;
992 err:
993 g_free(old_cluster);
994 return ret;
998 * Frees the allocated clusters because the request failed and they won't
999 * actually be linked.
1001 void qcow2_alloc_cluster_abort(BlockDriverState *bs, QCowL2Meta *m)
1003 BDRVQcow2State *s = bs->opaque;
1004 qcow2_free_clusters(bs, m->alloc_offset, m->nb_clusters << s->cluster_bits,
1005 QCOW2_DISCARD_NEVER);
1009 * Returns the number of contiguous clusters that can be used for an allocating
1010 * write, but require COW to be performed (this includes yet unallocated space,
1011 * which must copy from the backing file)
1013 static int count_cow_clusters(BDRVQcow2State *s, int nb_clusters,
1014 uint64_t *l2_slice, int l2_index)
1016 int i;
1018 for (i = 0; i < nb_clusters; i++) {
1019 uint64_t l2_entry = be64_to_cpu(l2_slice[l2_index + i]);
1020 QCow2ClusterType cluster_type = qcow2_get_cluster_type(l2_entry);
1022 switch(cluster_type) {
1023 case QCOW2_CLUSTER_NORMAL:
1024 if (l2_entry & QCOW_OFLAG_COPIED) {
1025 goto out;
1027 break;
1028 case QCOW2_CLUSTER_UNALLOCATED:
1029 case QCOW2_CLUSTER_COMPRESSED:
1030 case QCOW2_CLUSTER_ZERO_PLAIN:
1031 case QCOW2_CLUSTER_ZERO_ALLOC:
1032 break;
1033 default:
1034 abort();
1038 out:
1039 assert(i <= nb_clusters);
1040 return i;
1044 * Check if there already is an AIO write request in flight which allocates
1045 * the same cluster. In this case we need to wait until the previous
1046 * request has completed and updated the L2 table accordingly.
1048 * Returns:
1049 * 0 if there was no dependency. *cur_bytes indicates the number of
1050 * bytes from guest_offset that can be read before the next
1051 * dependency must be processed (or the request is complete)
1053 * -EAGAIN if we had to wait for another request, previously gathered
1054 * information on cluster allocation may be invalid now. The caller
1055 * must start over anyway, so consider *cur_bytes undefined.
1057 static int handle_dependencies(BlockDriverState *bs, uint64_t guest_offset,
1058 uint64_t *cur_bytes, QCowL2Meta **m)
1060 BDRVQcow2State *s = bs->opaque;
1061 QCowL2Meta *old_alloc;
1062 uint64_t bytes = *cur_bytes;
1064 QLIST_FOREACH(old_alloc, &s->cluster_allocs, next_in_flight) {
1066 uint64_t start = guest_offset;
1067 uint64_t end = start + bytes;
1068 uint64_t old_start = l2meta_cow_start(old_alloc);
1069 uint64_t old_end = l2meta_cow_end(old_alloc);
1071 if (end <= old_start || start >= old_end) {
1072 /* No intersection */
1073 } else {
1074 if (start < old_start) {
1075 /* Stop at the start of a running allocation */
1076 bytes = old_start - start;
1077 } else {
1078 bytes = 0;
1081 /* Stop if already an l2meta exists. After yielding, it wouldn't
1082 * be valid any more, so we'd have to clean up the old L2Metas
1083 * and deal with requests depending on them before starting to
1084 * gather new ones. Not worth the trouble. */
1085 if (bytes == 0 && *m) {
1086 *cur_bytes = 0;
1087 return 0;
1090 if (bytes == 0) {
1091 /* Wait for the dependency to complete. We need to recheck
1092 * the free/allocated clusters when we continue. */
1093 qemu_co_queue_wait(&old_alloc->dependent_requests, &s->lock);
1094 return -EAGAIN;
1099 /* Make sure that existing clusters and new allocations are only used up to
1100 * the next dependency if we shortened the request above */
1101 *cur_bytes = bytes;
1103 return 0;
1107 * Checks how many already allocated clusters that don't require a copy on
1108 * write there are at the given guest_offset (up to *bytes). If
1109 * *host_offset is not zero, only physically contiguous clusters beginning at
1110 * this host offset are counted.
1112 * Note that guest_offset may not be cluster aligned. In this case, the
1113 * returned *host_offset points to exact byte referenced by guest_offset and
1114 * therefore isn't cluster aligned as well.
1116 * Returns:
1117 * 0: if no allocated clusters are available at the given offset.
1118 * *bytes is normally unchanged. It is set to 0 if the cluster
1119 * is allocated and doesn't need COW, but doesn't have the right
1120 * physical offset.
1122 * 1: if allocated clusters that don't require a COW are available at
1123 * the requested offset. *bytes may have decreased and describes
1124 * the length of the area that can be written to.
1126 * -errno: in error cases
1128 static int handle_copied(BlockDriverState *bs, uint64_t guest_offset,
1129 uint64_t *host_offset, uint64_t *bytes, QCowL2Meta **m)
1131 BDRVQcow2State *s = bs->opaque;
1132 int l2_index;
1133 uint64_t cluster_offset;
1134 uint64_t *l2_slice;
1135 uint64_t nb_clusters;
1136 unsigned int keep_clusters;
1137 int ret;
1139 trace_qcow2_handle_copied(qemu_coroutine_self(), guest_offset, *host_offset,
1140 *bytes);
1142 assert(*host_offset == 0 || offset_into_cluster(s, guest_offset)
1143 == offset_into_cluster(s, *host_offset));
1146 * Calculate the number of clusters to look for. We stop at L2 slice
1147 * boundaries to keep things simple.
1149 nb_clusters =
1150 size_to_clusters(s, offset_into_cluster(s, guest_offset) + *bytes);
1152 l2_index = offset_to_l2_slice_index(s, guest_offset);
1153 nb_clusters = MIN(nb_clusters, s->l2_slice_size - l2_index);
1154 assert(nb_clusters <= INT_MAX);
1156 /* Find L2 entry for the first involved cluster */
1157 ret = get_cluster_table(bs, guest_offset, &l2_slice, &l2_index);
1158 if (ret < 0) {
1159 return ret;
1162 cluster_offset = be64_to_cpu(l2_slice[l2_index]);
1164 /* Check how many clusters are already allocated and don't need COW */
1165 if (qcow2_get_cluster_type(cluster_offset) == QCOW2_CLUSTER_NORMAL
1166 && (cluster_offset & QCOW_OFLAG_COPIED))
1168 /* If a specific host_offset is required, check it */
1169 bool offset_matches =
1170 (cluster_offset & L2E_OFFSET_MASK) == *host_offset;
1172 if (offset_into_cluster(s, cluster_offset & L2E_OFFSET_MASK)) {
1173 qcow2_signal_corruption(bs, true, -1, -1, "Data cluster offset "
1174 "%#llx unaligned (guest offset: %#" PRIx64
1175 ")", cluster_offset & L2E_OFFSET_MASK,
1176 guest_offset);
1177 ret = -EIO;
1178 goto out;
1181 if (*host_offset != 0 && !offset_matches) {
1182 *bytes = 0;
1183 ret = 0;
1184 goto out;
1187 /* We keep all QCOW_OFLAG_COPIED clusters */
1188 keep_clusters =
1189 count_contiguous_clusters(nb_clusters, s->cluster_size,
1190 &l2_slice[l2_index],
1191 QCOW_OFLAG_COPIED | QCOW_OFLAG_ZERO);
1192 assert(keep_clusters <= nb_clusters);
1194 *bytes = MIN(*bytes,
1195 keep_clusters * s->cluster_size
1196 - offset_into_cluster(s, guest_offset));
1198 ret = 1;
1199 } else {
1200 ret = 0;
1203 /* Cleanup */
1204 out:
1205 qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
1207 /* Only return a host offset if we actually made progress. Otherwise we
1208 * would make requirements for handle_alloc() that it can't fulfill */
1209 if (ret > 0) {
1210 *host_offset = (cluster_offset & L2E_OFFSET_MASK)
1211 + offset_into_cluster(s, guest_offset);
1214 return ret;
1218 * Allocates new clusters for the given guest_offset.
1220 * At most *nb_clusters are allocated, and on return *nb_clusters is updated to
1221 * contain the number of clusters that have been allocated and are contiguous
1222 * in the image file.
1224 * If *host_offset is non-zero, it specifies the offset in the image file at
1225 * which the new clusters must start. *nb_clusters can be 0 on return in this
1226 * case if the cluster at host_offset is already in use. If *host_offset is
1227 * zero, the clusters can be allocated anywhere in the image file.
1229 * *host_offset is updated to contain the offset into the image file at which
1230 * the first allocated cluster starts.
1232 * Return 0 on success and -errno in error cases. -EAGAIN means that the
1233 * function has been waiting for another request and the allocation must be
1234 * restarted, but the whole request should not be failed.
1236 static int do_alloc_cluster_offset(BlockDriverState *bs, uint64_t guest_offset,
1237 uint64_t *host_offset, uint64_t *nb_clusters)
1239 BDRVQcow2State *s = bs->opaque;
1241 trace_qcow2_do_alloc_clusters_offset(qemu_coroutine_self(), guest_offset,
1242 *host_offset, *nb_clusters);
1244 /* Allocate new clusters */
1245 trace_qcow2_cluster_alloc_phys(qemu_coroutine_self());
1246 if (*host_offset == 0) {
1247 int64_t cluster_offset =
1248 qcow2_alloc_clusters(bs, *nb_clusters * s->cluster_size);
1249 if (cluster_offset < 0) {
1250 return cluster_offset;
1252 *host_offset = cluster_offset;
1253 return 0;
1254 } else {
1255 int64_t ret = qcow2_alloc_clusters_at(bs, *host_offset, *nb_clusters);
1256 if (ret < 0) {
1257 return ret;
1259 *nb_clusters = ret;
1260 return 0;
1265 * Allocates new clusters for an area that either is yet unallocated or needs a
1266 * copy on write. If *host_offset is non-zero, clusters are only allocated if
1267 * the new allocation can match the specified host offset.
1269 * Note that guest_offset may not be cluster aligned. In this case, the
1270 * returned *host_offset points to exact byte referenced by guest_offset and
1271 * therefore isn't cluster aligned as well.
1273 * Returns:
1274 * 0: if no clusters could be allocated. *bytes is set to 0,
1275 * *host_offset is left unchanged.
1277 * 1: if new clusters were allocated. *bytes may be decreased if the
1278 * new allocation doesn't cover all of the requested area.
1279 * *host_offset is updated to contain the host offset of the first
1280 * newly allocated cluster.
1282 * -errno: in error cases
1284 static int handle_alloc(BlockDriverState *bs, uint64_t guest_offset,
1285 uint64_t *host_offset, uint64_t *bytes, QCowL2Meta **m)
1287 BDRVQcow2State *s = bs->opaque;
1288 int l2_index;
1289 uint64_t *l2_slice;
1290 uint64_t entry;
1291 uint64_t nb_clusters;
1292 int ret;
1293 bool keep_old_clusters = false;
1295 uint64_t alloc_cluster_offset = 0;
1297 trace_qcow2_handle_alloc(qemu_coroutine_self(), guest_offset, *host_offset,
1298 *bytes);
1299 assert(*bytes > 0);
1302 * Calculate the number of clusters to look for. We stop at L2 slice
1303 * boundaries to keep things simple.
1305 nb_clusters =
1306 size_to_clusters(s, offset_into_cluster(s, guest_offset) + *bytes);
1308 l2_index = offset_to_l2_slice_index(s, guest_offset);
1309 nb_clusters = MIN(nb_clusters, s->l2_slice_size - l2_index);
1310 assert(nb_clusters <= INT_MAX);
1312 /* Find L2 entry for the first involved cluster */
1313 ret = get_cluster_table(bs, guest_offset, &l2_slice, &l2_index);
1314 if (ret < 0) {
1315 return ret;
1318 entry = be64_to_cpu(l2_slice[l2_index]);
1320 /* For the moment, overwrite compressed clusters one by one */
1321 if (entry & QCOW_OFLAG_COMPRESSED) {
1322 nb_clusters = 1;
1323 } else {
1324 nb_clusters = count_cow_clusters(s, nb_clusters, l2_slice, l2_index);
1327 /* This function is only called when there were no non-COW clusters, so if
1328 * we can't find any unallocated or COW clusters either, something is
1329 * wrong with our code. */
1330 assert(nb_clusters > 0);
1332 if (qcow2_get_cluster_type(entry) == QCOW2_CLUSTER_ZERO_ALLOC &&
1333 (entry & QCOW_OFLAG_COPIED) &&
1334 (!*host_offset ||
1335 start_of_cluster(s, *host_offset) == (entry & L2E_OFFSET_MASK)))
1337 int preallocated_nb_clusters;
1339 if (offset_into_cluster(s, entry & L2E_OFFSET_MASK)) {
1340 qcow2_signal_corruption(bs, true, -1, -1, "Preallocated zero "
1341 "cluster offset %#llx unaligned (guest "
1342 "offset: %#" PRIx64 ")",
1343 entry & L2E_OFFSET_MASK, guest_offset);
1344 ret = -EIO;
1345 goto fail;
1348 /* Try to reuse preallocated zero clusters; contiguous normal clusters
1349 * would be fine, too, but count_cow_clusters() above has limited
1350 * nb_clusters already to a range of COW clusters */
1351 preallocated_nb_clusters =
1352 count_contiguous_clusters(nb_clusters, s->cluster_size,
1353 &l2_slice[l2_index], QCOW_OFLAG_COPIED);
1354 assert(preallocated_nb_clusters > 0);
1356 nb_clusters = preallocated_nb_clusters;
1357 alloc_cluster_offset = entry & L2E_OFFSET_MASK;
1359 /* We want to reuse these clusters, so qcow2_alloc_cluster_link_l2()
1360 * should not free them. */
1361 keep_old_clusters = true;
1364 qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
1366 if (!alloc_cluster_offset) {
1367 /* Allocate, if necessary at a given offset in the image file */
1368 alloc_cluster_offset = start_of_cluster(s, *host_offset);
1369 ret = do_alloc_cluster_offset(bs, guest_offset, &alloc_cluster_offset,
1370 &nb_clusters);
1371 if (ret < 0) {
1372 goto fail;
1375 /* Can't extend contiguous allocation */
1376 if (nb_clusters == 0) {
1377 *bytes = 0;
1378 return 0;
1381 /* !*host_offset would overwrite the image header and is reserved for
1382 * "no host offset preferred". If 0 was a valid host offset, it'd
1383 * trigger the following overlap check; do that now to avoid having an
1384 * invalid value in *host_offset. */
1385 if (!alloc_cluster_offset) {
1386 ret = qcow2_pre_write_overlap_check(bs, 0, alloc_cluster_offset,
1387 nb_clusters * s->cluster_size);
1388 assert(ret < 0);
1389 goto fail;
1394 * Save info needed for meta data update.
1396 * requested_bytes: Number of bytes from the start of the first
1397 * newly allocated cluster to the end of the (possibly shortened
1398 * before) write request.
1400 * avail_bytes: Number of bytes from the start of the first
1401 * newly allocated to the end of the last newly allocated cluster.
1403 * nb_bytes: The number of bytes from the start of the first
1404 * newly allocated cluster to the end of the area that the write
1405 * request actually writes to (excluding COW at the end)
1407 uint64_t requested_bytes = *bytes + offset_into_cluster(s, guest_offset);
1408 int avail_bytes = MIN(INT_MAX, nb_clusters << s->cluster_bits);
1409 int nb_bytes = MIN(requested_bytes, avail_bytes);
1410 QCowL2Meta *old_m = *m;
1412 *m = g_malloc0(sizeof(**m));
1414 **m = (QCowL2Meta) {
1415 .next = old_m,
1417 .alloc_offset = alloc_cluster_offset,
1418 .offset = start_of_cluster(s, guest_offset),
1419 .nb_clusters = nb_clusters,
1421 .keep_old_clusters = keep_old_clusters,
1423 .cow_start = {
1424 .offset = 0,
1425 .nb_bytes = offset_into_cluster(s, guest_offset),
1427 .cow_end = {
1428 .offset = nb_bytes,
1429 .nb_bytes = avail_bytes - nb_bytes,
1432 qemu_co_queue_init(&(*m)->dependent_requests);
1433 QLIST_INSERT_HEAD(&s->cluster_allocs, *m, next_in_flight);
1435 *host_offset = alloc_cluster_offset + offset_into_cluster(s, guest_offset);
1436 *bytes = MIN(*bytes, nb_bytes - offset_into_cluster(s, guest_offset));
1437 assert(*bytes != 0);
1439 return 1;
1441 fail:
1442 if (*m && (*m)->nb_clusters > 0) {
1443 QLIST_REMOVE(*m, next_in_flight);
1445 return ret;
1449 * alloc_cluster_offset
1451 * For a given offset on the virtual disk, find the cluster offset in qcow2
1452 * file. If the offset is not found, allocate a new cluster.
1454 * If the cluster was already allocated, m->nb_clusters is set to 0 and
1455 * other fields in m are meaningless.
1457 * If the cluster is newly allocated, m->nb_clusters is set to the number of
1458 * contiguous clusters that have been allocated. In this case, the other
1459 * fields of m are valid and contain information about the first allocated
1460 * cluster.
1462 * If the request conflicts with another write request in flight, the coroutine
1463 * is queued and will be reentered when the dependency has completed.
1465 * Return 0 on success and -errno in error cases
1467 int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset,
1468 unsigned int *bytes, uint64_t *host_offset,
1469 QCowL2Meta **m)
1471 BDRVQcow2State *s = bs->opaque;
1472 uint64_t start, remaining;
1473 uint64_t cluster_offset;
1474 uint64_t cur_bytes;
1475 int ret;
1477 trace_qcow2_alloc_clusters_offset(qemu_coroutine_self(), offset, *bytes);
1479 again:
1480 start = offset;
1481 remaining = *bytes;
1482 cluster_offset = 0;
1483 *host_offset = 0;
1484 cur_bytes = 0;
1485 *m = NULL;
1487 while (true) {
1489 if (!*host_offset) {
1490 *host_offset = start_of_cluster(s, cluster_offset);
1493 assert(remaining >= cur_bytes);
1495 start += cur_bytes;
1496 remaining -= cur_bytes;
1497 cluster_offset += cur_bytes;
1499 if (remaining == 0) {
1500 break;
1503 cur_bytes = remaining;
1506 * Now start gathering as many contiguous clusters as possible:
1508 * 1. Check for overlaps with in-flight allocations
1510 * a) Overlap not in the first cluster -> shorten this request and
1511 * let the caller handle the rest in its next loop iteration.
1513 * b) Real overlaps of two requests. Yield and restart the search
1514 * for contiguous clusters (the situation could have changed
1515 * while we were sleeping)
1517 * c) TODO: Request starts in the same cluster as the in-flight
1518 * allocation ends. Shorten the COW of the in-fight allocation,
1519 * set cluster_offset to write to the same cluster and set up
1520 * the right synchronisation between the in-flight request and
1521 * the new one.
1523 ret = handle_dependencies(bs, start, &cur_bytes, m);
1524 if (ret == -EAGAIN) {
1525 /* Currently handle_dependencies() doesn't yield if we already had
1526 * an allocation. If it did, we would have to clean up the L2Meta
1527 * structs before starting over. */
1528 assert(*m == NULL);
1529 goto again;
1530 } else if (ret < 0) {
1531 return ret;
1532 } else if (cur_bytes == 0) {
1533 break;
1534 } else {
1535 /* handle_dependencies() may have decreased cur_bytes (shortened
1536 * the allocations below) so that the next dependency is processed
1537 * correctly during the next loop iteration. */
1541 * 2. Count contiguous COPIED clusters.
1543 ret = handle_copied(bs, start, &cluster_offset, &cur_bytes, m);
1544 if (ret < 0) {
1545 return ret;
1546 } else if (ret) {
1547 continue;
1548 } else if (cur_bytes == 0) {
1549 break;
1553 * 3. If the request still hasn't completed, allocate new clusters,
1554 * considering any cluster_offset of steps 1c or 2.
1556 ret = handle_alloc(bs, start, &cluster_offset, &cur_bytes, m);
1557 if (ret < 0) {
1558 return ret;
1559 } else if (ret) {
1560 continue;
1561 } else {
1562 assert(cur_bytes == 0);
1563 break;
1567 *bytes -= remaining;
1568 assert(*bytes > 0);
1569 assert(*host_offset != 0);
1571 return 0;
1574 static int decompress_buffer(uint8_t *out_buf, int out_buf_size,
1575 const uint8_t *buf, int buf_size)
1577 z_stream strm1, *strm = &strm1;
1578 int ret, out_len;
1580 memset(strm, 0, sizeof(*strm));
1582 strm->next_in = (uint8_t *)buf;
1583 strm->avail_in = buf_size;
1584 strm->next_out = out_buf;
1585 strm->avail_out = out_buf_size;
1587 ret = inflateInit2(strm, -12);
1588 if (ret != Z_OK)
1589 return -1;
1590 ret = inflate(strm, Z_FINISH);
1591 out_len = strm->next_out - out_buf;
1592 if ((ret != Z_STREAM_END && ret != Z_BUF_ERROR) ||
1593 out_len != out_buf_size) {
1594 inflateEnd(strm);
1595 return -1;
1597 inflateEnd(strm);
1598 return 0;
1601 int qcow2_decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset)
1603 BDRVQcow2State *s = bs->opaque;
1604 int ret, csize, nb_csectors, sector_offset;
1605 uint64_t coffset;
1607 coffset = cluster_offset & s->cluster_offset_mask;
1608 if (s->cluster_cache_offset != coffset) {
1609 nb_csectors = ((cluster_offset >> s->csize_shift) & s->csize_mask) + 1;
1610 sector_offset = coffset & 511;
1611 csize = nb_csectors * 512 - sector_offset;
1613 /* Allocate buffers on first decompress operation, most images are
1614 * uncompressed and the memory overhead can be avoided. The buffers
1615 * are freed in .bdrv_close().
1617 if (!s->cluster_data) {
1618 /* one more sector for decompressed data alignment */
1619 s->cluster_data = qemu_try_blockalign(bs->file->bs,
1620 QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size + 512);
1621 if (!s->cluster_data) {
1622 return -ENOMEM;
1625 if (!s->cluster_cache) {
1626 s->cluster_cache = g_malloc(s->cluster_size);
1629 BLKDBG_EVENT(bs->file, BLKDBG_READ_COMPRESSED);
1630 ret = bdrv_read(bs->file, coffset >> 9, s->cluster_data,
1631 nb_csectors);
1632 if (ret < 0) {
1633 return ret;
1635 if (decompress_buffer(s->cluster_cache, s->cluster_size,
1636 s->cluster_data + sector_offset, csize) < 0) {
1637 return -EIO;
1639 s->cluster_cache_offset = coffset;
1641 return 0;
1645 * This discards as many clusters of nb_clusters as possible at once (i.e.
1646 * all clusters in the same L2 slice) and returns the number of discarded
1647 * clusters.
1649 static int discard_in_l2_slice(BlockDriverState *bs, uint64_t offset,
1650 uint64_t nb_clusters,
1651 enum qcow2_discard_type type, bool full_discard)
1653 BDRVQcow2State *s = bs->opaque;
1654 uint64_t *l2_slice;
1655 int l2_index;
1656 int ret;
1657 int i;
1659 ret = get_cluster_table(bs, offset, &l2_slice, &l2_index);
1660 if (ret < 0) {
1661 return ret;
1664 /* Limit nb_clusters to one L2 slice */
1665 nb_clusters = MIN(nb_clusters, s->l2_slice_size - l2_index);
1666 assert(nb_clusters <= INT_MAX);
1668 for (i = 0; i < nb_clusters; i++) {
1669 uint64_t old_l2_entry;
1671 old_l2_entry = be64_to_cpu(l2_slice[l2_index + i]);
1674 * If full_discard is false, make sure that a discarded area reads back
1675 * as zeroes for v3 images (we cannot do it for v2 without actually
1676 * writing a zero-filled buffer). We can skip the operation if the
1677 * cluster is already marked as zero, or if it's unallocated and we
1678 * don't have a backing file.
1680 * TODO We might want to use bdrv_block_status(bs) here, but we're
1681 * holding s->lock, so that doesn't work today.
1683 * If full_discard is true, the sector should not read back as zeroes,
1684 * but rather fall through to the backing file.
1686 switch (qcow2_get_cluster_type(old_l2_entry)) {
1687 case QCOW2_CLUSTER_UNALLOCATED:
1688 if (full_discard || !bs->backing) {
1689 continue;
1691 break;
1693 case QCOW2_CLUSTER_ZERO_PLAIN:
1694 if (!full_discard) {
1695 continue;
1697 break;
1699 case QCOW2_CLUSTER_ZERO_ALLOC:
1700 case QCOW2_CLUSTER_NORMAL:
1701 case QCOW2_CLUSTER_COMPRESSED:
1702 break;
1704 default:
1705 abort();
1708 /* First remove L2 entries */
1709 qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice);
1710 if (!full_discard && s->qcow_version >= 3) {
1711 l2_slice[l2_index + i] = cpu_to_be64(QCOW_OFLAG_ZERO);
1712 } else {
1713 l2_slice[l2_index + i] = cpu_to_be64(0);
1716 /* Then decrease the refcount */
1717 qcow2_free_any_clusters(bs, old_l2_entry, 1, type);
1720 qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
1722 return nb_clusters;
1725 int qcow2_cluster_discard(BlockDriverState *bs, uint64_t offset,
1726 uint64_t bytes, enum qcow2_discard_type type,
1727 bool full_discard)
1729 BDRVQcow2State *s = bs->opaque;
1730 uint64_t end_offset = offset + bytes;
1731 uint64_t nb_clusters;
1732 int64_t cleared;
1733 int ret;
1735 /* Caller must pass aligned values, except at image end */
1736 assert(QEMU_IS_ALIGNED(offset, s->cluster_size));
1737 assert(QEMU_IS_ALIGNED(end_offset, s->cluster_size) ||
1738 end_offset == bs->total_sectors << BDRV_SECTOR_BITS);
1740 nb_clusters = size_to_clusters(s, bytes);
1742 s->cache_discards = true;
1744 /* Each L2 slice is handled by its own loop iteration */
1745 while (nb_clusters > 0) {
1746 cleared = discard_in_l2_slice(bs, offset, nb_clusters, type,
1747 full_discard);
1748 if (cleared < 0) {
1749 ret = cleared;
1750 goto fail;
1753 nb_clusters -= cleared;
1754 offset += (cleared * s->cluster_size);
1757 ret = 0;
1758 fail:
1759 s->cache_discards = false;
1760 qcow2_process_discards(bs, ret);
1762 return ret;
1766 * This zeroes as many clusters of nb_clusters as possible at once (i.e.
1767 * all clusters in the same L2 slice) and returns the number of zeroed
1768 * clusters.
1770 static int zero_in_l2_slice(BlockDriverState *bs, uint64_t offset,
1771 uint64_t nb_clusters, int flags)
1773 BDRVQcow2State *s = bs->opaque;
1774 uint64_t *l2_slice;
1775 int l2_index;
1776 int ret;
1777 int i;
1778 bool unmap = !!(flags & BDRV_REQ_MAY_UNMAP);
1780 ret = get_cluster_table(bs, offset, &l2_slice, &l2_index);
1781 if (ret < 0) {
1782 return ret;
1785 /* Limit nb_clusters to one L2 slice */
1786 nb_clusters = MIN(nb_clusters, s->l2_slice_size - l2_index);
1787 assert(nb_clusters <= INT_MAX);
1789 for (i = 0; i < nb_clusters; i++) {
1790 uint64_t old_offset;
1791 QCow2ClusterType cluster_type;
1793 old_offset = be64_to_cpu(l2_slice[l2_index + i]);
1796 * Minimize L2 changes if the cluster already reads back as
1797 * zeroes with correct allocation.
1799 cluster_type = qcow2_get_cluster_type(old_offset);
1800 if (cluster_type == QCOW2_CLUSTER_ZERO_PLAIN ||
1801 (cluster_type == QCOW2_CLUSTER_ZERO_ALLOC && !unmap)) {
1802 continue;
1805 qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice);
1806 if (cluster_type == QCOW2_CLUSTER_COMPRESSED || unmap) {
1807 l2_slice[l2_index + i] = cpu_to_be64(QCOW_OFLAG_ZERO);
1808 qcow2_free_any_clusters(bs, old_offset, 1, QCOW2_DISCARD_REQUEST);
1809 } else {
1810 l2_slice[l2_index + i] |= cpu_to_be64(QCOW_OFLAG_ZERO);
1814 qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
1816 return nb_clusters;
1819 int qcow2_cluster_zeroize(BlockDriverState *bs, uint64_t offset,
1820 uint64_t bytes, int flags)
1822 BDRVQcow2State *s = bs->opaque;
1823 uint64_t end_offset = offset + bytes;
1824 uint64_t nb_clusters;
1825 int64_t cleared;
1826 int ret;
1828 /* Caller must pass aligned values, except at image end */
1829 assert(QEMU_IS_ALIGNED(offset, s->cluster_size));
1830 assert(QEMU_IS_ALIGNED(end_offset, s->cluster_size) ||
1831 end_offset == bs->total_sectors << BDRV_SECTOR_BITS);
1833 /* The zero flag is only supported by version 3 and newer */
1834 if (s->qcow_version < 3) {
1835 return -ENOTSUP;
1838 /* Each L2 slice is handled by its own loop iteration */
1839 nb_clusters = size_to_clusters(s, bytes);
1841 s->cache_discards = true;
1843 while (nb_clusters > 0) {
1844 cleared = zero_in_l2_slice(bs, offset, nb_clusters, flags);
1845 if (cleared < 0) {
1846 ret = cleared;
1847 goto fail;
1850 nb_clusters -= cleared;
1851 offset += (cleared * s->cluster_size);
1854 ret = 0;
1855 fail:
1856 s->cache_discards = false;
1857 qcow2_process_discards(bs, ret);
1859 return ret;
1863 * Expands all zero clusters in a specific L1 table (or deallocates them, for
1864 * non-backed non-pre-allocated zero clusters).
1866 * l1_entries and *visited_l1_entries are used to keep track of progress for
1867 * status_cb(). l1_entries contains the total number of L1 entries and
1868 * *visited_l1_entries counts all visited L1 entries.
1870 static int expand_zero_clusters_in_l1(BlockDriverState *bs, uint64_t *l1_table,
1871 int l1_size, int64_t *visited_l1_entries,
1872 int64_t l1_entries,
1873 BlockDriverAmendStatusCB *status_cb,
1874 void *cb_opaque)
1876 BDRVQcow2State *s = bs->opaque;
1877 bool is_active_l1 = (l1_table == s->l1_table);
1878 uint64_t *l2_slice = NULL;
1879 unsigned slice, slice_size2, n_slices;
1880 int ret;
1881 int i, j;
1883 slice_size2 = s->l2_slice_size * sizeof(uint64_t);
1884 n_slices = s->cluster_size / slice_size2;
1886 if (!is_active_l1) {
1887 /* inactive L2 tables require a buffer to be stored in when loading
1888 * them from disk */
1889 l2_slice = qemu_try_blockalign(bs->file->bs, slice_size2);
1890 if (l2_slice == NULL) {
1891 return -ENOMEM;
1895 for (i = 0; i < l1_size; i++) {
1896 uint64_t l2_offset = l1_table[i] & L1E_OFFSET_MASK;
1897 uint64_t l2_refcount;
1899 if (!l2_offset) {
1900 /* unallocated */
1901 (*visited_l1_entries)++;
1902 if (status_cb) {
1903 status_cb(bs, *visited_l1_entries, l1_entries, cb_opaque);
1905 continue;
1908 if (offset_into_cluster(s, l2_offset)) {
1909 qcow2_signal_corruption(bs, true, -1, -1, "L2 table offset %#"
1910 PRIx64 " unaligned (L1 index: %#x)",
1911 l2_offset, i);
1912 ret = -EIO;
1913 goto fail;
1916 ret = qcow2_get_refcount(bs, l2_offset >> s->cluster_bits,
1917 &l2_refcount);
1918 if (ret < 0) {
1919 goto fail;
1922 for (slice = 0; slice < n_slices; slice++) {
1923 uint64_t slice_offset = l2_offset + slice * slice_size2;
1924 bool l2_dirty = false;
1925 if (is_active_l1) {
1926 /* get active L2 tables from cache */
1927 ret = qcow2_cache_get(bs, s->l2_table_cache, slice_offset,
1928 (void **)&l2_slice);
1929 } else {
1930 /* load inactive L2 tables from disk */
1931 ret = bdrv_pread(bs->file, slice_offset, l2_slice, slice_size2);
1933 if (ret < 0) {
1934 goto fail;
1937 for (j = 0; j < s->l2_slice_size; j++) {
1938 uint64_t l2_entry = be64_to_cpu(l2_slice[j]);
1939 int64_t offset = l2_entry & L2E_OFFSET_MASK;
1940 QCow2ClusterType cluster_type =
1941 qcow2_get_cluster_type(l2_entry);
1943 if (cluster_type != QCOW2_CLUSTER_ZERO_PLAIN &&
1944 cluster_type != QCOW2_CLUSTER_ZERO_ALLOC) {
1945 continue;
1948 if (cluster_type == QCOW2_CLUSTER_ZERO_PLAIN) {
1949 if (!bs->backing) {
1950 /* not backed; therefore we can simply deallocate the
1951 * cluster */
1952 l2_slice[j] = 0;
1953 l2_dirty = true;
1954 continue;
1957 offset = qcow2_alloc_clusters(bs, s->cluster_size);
1958 if (offset < 0) {
1959 ret = offset;
1960 goto fail;
1963 if (l2_refcount > 1) {
1964 /* For shared L2 tables, set the refcount accordingly
1965 * (it is already 1 and needs to be l2_refcount) */
1966 ret = qcow2_update_cluster_refcount(
1967 bs, offset >> s->cluster_bits,
1968 refcount_diff(1, l2_refcount), false,
1969 QCOW2_DISCARD_OTHER);
1970 if (ret < 0) {
1971 qcow2_free_clusters(bs, offset, s->cluster_size,
1972 QCOW2_DISCARD_OTHER);
1973 goto fail;
1978 if (offset_into_cluster(s, offset)) {
1979 int l2_index = slice * s->l2_slice_size + j;
1980 qcow2_signal_corruption(
1981 bs, true, -1, -1,
1982 "Cluster allocation offset "
1983 "%#" PRIx64 " unaligned (L2 offset: %#"
1984 PRIx64 ", L2 index: %#x)", offset,
1985 l2_offset, l2_index);
1986 if (cluster_type == QCOW2_CLUSTER_ZERO_PLAIN) {
1987 qcow2_free_clusters(bs, offset, s->cluster_size,
1988 QCOW2_DISCARD_ALWAYS);
1990 ret = -EIO;
1991 goto fail;
1994 ret = qcow2_pre_write_overlap_check(bs, 0, offset,
1995 s->cluster_size);
1996 if (ret < 0) {
1997 if (cluster_type == QCOW2_CLUSTER_ZERO_PLAIN) {
1998 qcow2_free_clusters(bs, offset, s->cluster_size,
1999 QCOW2_DISCARD_ALWAYS);
2001 goto fail;
2004 ret = bdrv_pwrite_zeroes(bs->file, offset, s->cluster_size, 0);
2005 if (ret < 0) {
2006 if (cluster_type == QCOW2_CLUSTER_ZERO_PLAIN) {
2007 qcow2_free_clusters(bs, offset, s->cluster_size,
2008 QCOW2_DISCARD_ALWAYS);
2010 goto fail;
2013 if (l2_refcount == 1) {
2014 l2_slice[j] = cpu_to_be64(offset | QCOW_OFLAG_COPIED);
2015 } else {
2016 l2_slice[j] = cpu_to_be64(offset);
2018 l2_dirty = true;
2021 if (is_active_l1) {
2022 if (l2_dirty) {
2023 qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice);
2024 qcow2_cache_depends_on_flush(s->l2_table_cache);
2026 qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
2027 } else {
2028 if (l2_dirty) {
2029 ret = qcow2_pre_write_overlap_check(
2030 bs, QCOW2_OL_INACTIVE_L2 | QCOW2_OL_ACTIVE_L2,
2031 slice_offset, slice_size2);
2032 if (ret < 0) {
2033 goto fail;
2036 ret = bdrv_pwrite(bs->file, slice_offset,
2037 l2_slice, slice_size2);
2038 if (ret < 0) {
2039 goto fail;
2045 (*visited_l1_entries)++;
2046 if (status_cb) {
2047 status_cb(bs, *visited_l1_entries, l1_entries, cb_opaque);
2051 ret = 0;
2053 fail:
2054 if (l2_slice) {
2055 if (!is_active_l1) {
2056 qemu_vfree(l2_slice);
2057 } else {
2058 qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
2061 return ret;
2065 * For backed images, expands all zero clusters on the image. For non-backed
2066 * images, deallocates all non-pre-allocated zero clusters (and claims the
2067 * allocation for pre-allocated ones). This is important for downgrading to a
2068 * qcow2 version which doesn't yet support metadata zero clusters.
2070 int qcow2_expand_zero_clusters(BlockDriverState *bs,
2071 BlockDriverAmendStatusCB *status_cb,
2072 void *cb_opaque)
2074 BDRVQcow2State *s = bs->opaque;
2075 uint64_t *l1_table = NULL;
2076 int64_t l1_entries = 0, visited_l1_entries = 0;
2077 int ret;
2078 int i, j;
2080 if (status_cb) {
2081 l1_entries = s->l1_size;
2082 for (i = 0; i < s->nb_snapshots; i++) {
2083 l1_entries += s->snapshots[i].l1_size;
2087 ret = expand_zero_clusters_in_l1(bs, s->l1_table, s->l1_size,
2088 &visited_l1_entries, l1_entries,
2089 status_cb, cb_opaque);
2090 if (ret < 0) {
2091 goto fail;
2094 /* Inactive L1 tables may point to active L2 tables - therefore it is
2095 * necessary to flush the L2 table cache before trying to access the L2
2096 * tables pointed to by inactive L1 entries (else we might try to expand
2097 * zero clusters that have already been expanded); furthermore, it is also
2098 * necessary to empty the L2 table cache, since it may contain tables which
2099 * are now going to be modified directly on disk, bypassing the cache.
2100 * qcow2_cache_empty() does both for us. */
2101 ret = qcow2_cache_empty(bs, s->l2_table_cache);
2102 if (ret < 0) {
2103 goto fail;
2106 for (i = 0; i < s->nb_snapshots; i++) {
2107 int l1_size2;
2108 uint64_t *new_l1_table;
2109 Error *local_err = NULL;
2111 ret = qcow2_validate_table(bs, s->snapshots[i].l1_table_offset,
2112 s->snapshots[i].l1_size, sizeof(uint64_t),
2113 QCOW_MAX_L1_SIZE, "Snapshot L1 table",
2114 &local_err);
2115 if (ret < 0) {
2116 error_report_err(local_err);
2117 goto fail;
2120 l1_size2 = s->snapshots[i].l1_size * sizeof(uint64_t);
2121 new_l1_table = g_try_realloc(l1_table, l1_size2);
2123 if (!new_l1_table) {
2124 ret = -ENOMEM;
2125 goto fail;
2128 l1_table = new_l1_table;
2130 ret = bdrv_pread(bs->file, s->snapshots[i].l1_table_offset,
2131 l1_table, l1_size2);
2132 if (ret < 0) {
2133 goto fail;
2136 for (j = 0; j < s->snapshots[i].l1_size; j++) {
2137 be64_to_cpus(&l1_table[j]);
2140 ret = expand_zero_clusters_in_l1(bs, l1_table, s->snapshots[i].l1_size,
2141 &visited_l1_entries, l1_entries,
2142 status_cb, cb_opaque);
2143 if (ret < 0) {
2144 goto fail;
2148 ret = 0;
2150 fail:
2151 g_free(l1_table);
2152 return ret;