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
25 #include "qemu-common.h"
26 #include "block/block_int.h"
27 #include "block/qcow2.h"
28 #include "qemu/range.h"
29 #include "qapi/qmp/types.h"
31 static int64_t alloc_clusters_noref(BlockDriverState
*bs
, uint64_t size
);
32 static int QEMU_WARN_UNUSED_RESULT
update_refcount(BlockDriverState
*bs
,
33 int64_t offset
, int64_t length
,
34 int addend
, enum qcow2_discard_type type
);
37 /*********************************************************/
38 /* refcount handling */
40 int qcow2_refcount_init(BlockDriverState
*bs
)
42 BDRVQcowState
*s
= bs
->opaque
;
43 unsigned int refcount_table_size2
, i
;
46 assert(s
->refcount_table_size
<= INT_MAX
/ sizeof(uint64_t));
47 refcount_table_size2
= s
->refcount_table_size
* sizeof(uint64_t);
48 s
->refcount_table
= g_malloc(refcount_table_size2
);
49 if (s
->refcount_table_size
> 0) {
50 BLKDBG_EVENT(bs
->file
, BLKDBG_REFTABLE_LOAD
);
51 ret
= bdrv_pread(bs
->file
, s
->refcount_table_offset
,
52 s
->refcount_table
, refcount_table_size2
);
53 if (ret
!= refcount_table_size2
)
55 for(i
= 0; i
< s
->refcount_table_size
; i
++)
56 be64_to_cpus(&s
->refcount_table
[i
]);
63 void qcow2_refcount_close(BlockDriverState
*bs
)
65 BDRVQcowState
*s
= bs
->opaque
;
66 g_free(s
->refcount_table
);
70 static int load_refcount_block(BlockDriverState
*bs
,
71 int64_t refcount_block_offset
,
72 void **refcount_block
)
74 BDRVQcowState
*s
= bs
->opaque
;
77 BLKDBG_EVENT(bs
->file
, BLKDBG_REFBLOCK_LOAD
);
78 ret
= qcow2_cache_get(bs
, s
->refcount_block_cache
, refcount_block_offset
,
85 * Returns the refcount of the cluster given by its index. Any non-negative
86 * return value is the refcount of the cluster, negative values are -errno
87 * and indicate an error.
89 static int get_refcount(BlockDriverState
*bs
, int64_t cluster_index
)
91 BDRVQcowState
*s
= bs
->opaque
;
92 uint64_t refcount_table_index
, block_index
;
93 int64_t refcount_block_offset
;
95 uint16_t *refcount_block
;
98 refcount_table_index
= cluster_index
>> (s
->cluster_bits
- REFCOUNT_SHIFT
);
99 if (refcount_table_index
>= s
->refcount_table_size
)
101 refcount_block_offset
=
102 s
->refcount_table
[refcount_table_index
] & REFT_OFFSET_MASK
;
103 if (!refcount_block_offset
)
106 ret
= qcow2_cache_get(bs
, s
->refcount_block_cache
, refcount_block_offset
,
107 (void**) &refcount_block
);
112 block_index
= cluster_index
&
113 ((1 << (s
->cluster_bits
- REFCOUNT_SHIFT
)) - 1);
114 refcount
= be16_to_cpu(refcount_block
[block_index
]);
116 ret
= qcow2_cache_put(bs
, s
->refcount_block_cache
,
117 (void**) &refcount_block
);
126 * Rounds the refcount table size up to avoid growing the table for each single
127 * refcount block that is allocated.
129 static unsigned int next_refcount_table_size(BDRVQcowState
*s
,
130 unsigned int min_size
)
132 unsigned int min_clusters
= (min_size
>> (s
->cluster_bits
- 3)) + 1;
133 unsigned int refcount_table_clusters
=
134 MAX(1, s
->refcount_table_size
>> (s
->cluster_bits
- 3));
136 while (min_clusters
> refcount_table_clusters
) {
137 refcount_table_clusters
= (refcount_table_clusters
* 3 + 1) / 2;
140 return refcount_table_clusters
<< (s
->cluster_bits
- 3);
144 /* Checks if two offsets are described by the same refcount block */
145 static int in_same_refcount_block(BDRVQcowState
*s
, uint64_t offset_a
,
148 uint64_t block_a
= offset_a
>> (2 * s
->cluster_bits
- REFCOUNT_SHIFT
);
149 uint64_t block_b
= offset_b
>> (2 * s
->cluster_bits
- REFCOUNT_SHIFT
);
151 return (block_a
== block_b
);
155 * Loads a refcount block. If it doesn't exist yet, it is allocated first
156 * (including growing the refcount table if needed).
158 * Returns 0 on success or -errno in error case
160 static int alloc_refcount_block(BlockDriverState
*bs
,
161 int64_t cluster_index
, uint16_t **refcount_block
)
163 BDRVQcowState
*s
= bs
->opaque
;
164 unsigned int refcount_table_index
;
167 BLKDBG_EVENT(bs
->file
, BLKDBG_REFBLOCK_ALLOC
);
169 /* Find the refcount block for the given cluster */
170 refcount_table_index
= cluster_index
>> (s
->cluster_bits
- REFCOUNT_SHIFT
);
172 if (refcount_table_index
< s
->refcount_table_size
) {
174 uint64_t refcount_block_offset
=
175 s
->refcount_table
[refcount_table_index
] & REFT_OFFSET_MASK
;
177 /* If it's already there, we're done */
178 if (refcount_block_offset
) {
179 return load_refcount_block(bs
, refcount_block_offset
,
180 (void**) refcount_block
);
185 * If we came here, we need to allocate something. Something is at least
186 * a cluster for the new refcount block. It may also include a new refcount
187 * table if the old refcount table is too small.
189 * Note that allocating clusters here needs some special care:
191 * - We can't use the normal qcow2_alloc_clusters(), it would try to
192 * increase the refcount and very likely we would end up with an endless
193 * recursion. Instead we must place the refcount blocks in a way that
194 * they can describe them themselves.
196 * - We need to consider that at this point we are inside update_refcounts
197 * and potentially doing an initial refcount increase. This means that
198 * some clusters have already been allocated by the caller, but their
199 * refcount isn't accurate yet. If we allocate clusters for metadata, we
200 * need to return -EAGAIN to signal the caller that it needs to restart
201 * the search for free clusters.
203 * - alloc_clusters_noref and qcow2_free_clusters may load a different
204 * refcount block into the cache
207 *refcount_block
= NULL
;
209 /* We write to the refcount table, so we might depend on L2 tables */
210 ret
= qcow2_cache_flush(bs
, s
->l2_table_cache
);
215 /* Allocate the refcount block itself and mark it as used */
216 int64_t new_block
= alloc_clusters_noref(bs
, s
->cluster_size
);
222 fprintf(stderr
, "qcow2: Allocate refcount block %d for %" PRIx64
224 refcount_table_index
, cluster_index
<< s
->cluster_bits
, new_block
);
227 if (in_same_refcount_block(s
, new_block
, cluster_index
<< s
->cluster_bits
)) {
228 /* Zero the new refcount block before updating it */
229 ret
= qcow2_cache_get_empty(bs
, s
->refcount_block_cache
, new_block
,
230 (void**) refcount_block
);
235 memset(*refcount_block
, 0, s
->cluster_size
);
237 /* The block describes itself, need to update the cache */
238 int block_index
= (new_block
>> s
->cluster_bits
) &
239 ((1 << (s
->cluster_bits
- REFCOUNT_SHIFT
)) - 1);
240 (*refcount_block
)[block_index
] = cpu_to_be16(1);
242 /* Described somewhere else. This can recurse at most twice before we
243 * arrive at a block that describes itself. */
244 ret
= update_refcount(bs
, new_block
, s
->cluster_size
, 1,
245 QCOW2_DISCARD_NEVER
);
250 ret
= qcow2_cache_flush(bs
, s
->refcount_block_cache
);
255 /* Initialize the new refcount block only after updating its refcount,
256 * update_refcount uses the refcount cache itself */
257 ret
= qcow2_cache_get_empty(bs
, s
->refcount_block_cache
, new_block
,
258 (void**) refcount_block
);
263 memset(*refcount_block
, 0, s
->cluster_size
);
266 /* Now the new refcount block needs to be written to disk */
267 BLKDBG_EVENT(bs
->file
, BLKDBG_REFBLOCK_ALLOC_WRITE
);
268 qcow2_cache_entry_mark_dirty(s
->refcount_block_cache
, *refcount_block
);
269 ret
= qcow2_cache_flush(bs
, s
->refcount_block_cache
);
274 /* If the refcount table is big enough, just hook the block up there */
275 if (refcount_table_index
< s
->refcount_table_size
) {
276 uint64_t data64
= cpu_to_be64(new_block
);
277 BLKDBG_EVENT(bs
->file
, BLKDBG_REFBLOCK_ALLOC_HOOKUP
);
278 ret
= bdrv_pwrite_sync(bs
->file
,
279 s
->refcount_table_offset
+ refcount_table_index
* sizeof(uint64_t),
280 &data64
, sizeof(data64
));
285 s
->refcount_table
[refcount_table_index
] = new_block
;
287 /* The new refcount block may be where the caller intended to put its
288 * data, so let it restart the search. */
292 ret
= qcow2_cache_put(bs
, s
->refcount_block_cache
, (void**) refcount_block
);
298 * If we come here, we need to grow the refcount table. Again, a new
299 * refcount table needs some space and we can't simply allocate to avoid
302 * Therefore let's grab new refcount blocks at the end of the image, which
303 * will describe themselves and the new refcount table. This way we can
304 * reference them only in the new table and do the switch to the new
305 * refcount table at once without producing an inconsistent state in
308 BLKDBG_EVENT(bs
->file
, BLKDBG_REFTABLE_GROW
);
310 /* Calculate the number of refcount blocks needed so far */
311 uint64_t refcount_block_clusters
= 1 << (s
->cluster_bits
- REFCOUNT_SHIFT
);
312 uint64_t blocks_used
= DIV_ROUND_UP(cluster_index
, refcount_block_clusters
);
314 if (blocks_used
> QCOW_MAX_REFTABLE_SIZE
/ sizeof(uint64_t)) {
318 /* And now we need at least one block more for the new metadata */
319 uint64_t table_size
= next_refcount_table_size(s
, blocks_used
+ 1);
320 uint64_t last_table_size
;
321 uint64_t blocks_clusters
;
323 uint64_t table_clusters
=
324 size_to_clusters(s
, table_size
* sizeof(uint64_t));
325 blocks_clusters
= 1 +
326 ((table_clusters
+ refcount_block_clusters
- 1)
327 / refcount_block_clusters
);
328 uint64_t meta_clusters
= table_clusters
+ blocks_clusters
;
330 last_table_size
= table_size
;
331 table_size
= next_refcount_table_size(s
, blocks_used
+
332 ((meta_clusters
+ refcount_block_clusters
- 1)
333 / refcount_block_clusters
));
335 } while (last_table_size
!= table_size
);
338 fprintf(stderr
, "qcow2: Grow refcount table %" PRId32
" => %" PRId64
"\n",
339 s
->refcount_table_size
, table_size
);
342 /* Create the new refcount table and blocks */
343 uint64_t meta_offset
= (blocks_used
* refcount_block_clusters
) *
345 uint64_t table_offset
= meta_offset
+ blocks_clusters
* s
->cluster_size
;
346 uint16_t *new_blocks
= g_malloc0(blocks_clusters
* s
->cluster_size
);
347 uint64_t *new_table
= g_malloc0(table_size
* sizeof(uint64_t));
349 /* Fill the new refcount table */
350 memcpy(new_table
, s
->refcount_table
,
351 s
->refcount_table_size
* sizeof(uint64_t));
352 new_table
[refcount_table_index
] = new_block
;
355 for (i
= 0; i
< blocks_clusters
; i
++) {
356 new_table
[blocks_used
+ i
] = meta_offset
+ (i
* s
->cluster_size
);
359 /* Fill the refcount blocks */
360 uint64_t table_clusters
= size_to_clusters(s
, table_size
* sizeof(uint64_t));
362 for (i
= 0; i
< table_clusters
+ blocks_clusters
; i
++) {
363 new_blocks
[block
++] = cpu_to_be16(1);
366 /* Write refcount blocks to disk */
367 BLKDBG_EVENT(bs
->file
, BLKDBG_REFBLOCK_ALLOC_WRITE_BLOCKS
);
368 ret
= bdrv_pwrite_sync(bs
->file
, meta_offset
, new_blocks
,
369 blocks_clusters
* s
->cluster_size
);
375 /* Write refcount table to disk */
376 for(i
= 0; i
< table_size
; i
++) {
377 cpu_to_be64s(&new_table
[i
]);
380 BLKDBG_EVENT(bs
->file
, BLKDBG_REFBLOCK_ALLOC_WRITE_TABLE
);
381 ret
= bdrv_pwrite_sync(bs
->file
, table_offset
, new_table
,
382 table_size
* sizeof(uint64_t));
387 for(i
= 0; i
< table_size
; i
++) {
388 be64_to_cpus(&new_table
[i
]);
391 /* Hook up the new refcount table in the qcow2 header */
393 cpu_to_be64w((uint64_t*)data
, table_offset
);
394 cpu_to_be32w((uint32_t*)(data
+ 8), table_clusters
);
395 BLKDBG_EVENT(bs
->file
, BLKDBG_REFBLOCK_ALLOC_SWITCH_TABLE
);
396 ret
= bdrv_pwrite_sync(bs
->file
, offsetof(QCowHeader
, refcount_table_offset
),
402 /* And switch it in memory */
403 uint64_t old_table_offset
= s
->refcount_table_offset
;
404 uint64_t old_table_size
= s
->refcount_table_size
;
406 g_free(s
->refcount_table
);
407 s
->refcount_table
= new_table
;
408 s
->refcount_table_size
= table_size
;
409 s
->refcount_table_offset
= table_offset
;
411 /* Free old table. */
412 qcow2_free_clusters(bs
, old_table_offset
, old_table_size
* sizeof(uint64_t),
413 QCOW2_DISCARD_OTHER
);
415 ret
= load_refcount_block(bs
, new_block
, (void**) refcount_block
);
420 /* If we were trying to do the initial refcount update for some cluster
421 * allocation, we might have used the same clusters to store newly
422 * allocated metadata. Make the caller search some new space. */
428 if (*refcount_block
!= NULL
) {
429 qcow2_cache_put(bs
, s
->refcount_block_cache
, (void**) refcount_block
);
434 void qcow2_process_discards(BlockDriverState
*bs
, int ret
)
436 BDRVQcowState
*s
= bs
->opaque
;
437 Qcow2DiscardRegion
*d
, *next
;
439 QTAILQ_FOREACH_SAFE(d
, &s
->discards
, next
, next
) {
440 QTAILQ_REMOVE(&s
->discards
, d
, next
);
442 /* Discard is optional, ignore the return value */
444 bdrv_discard(bs
->file
,
445 d
->offset
>> BDRV_SECTOR_BITS
,
446 d
->bytes
>> BDRV_SECTOR_BITS
);
453 static void update_refcount_discard(BlockDriverState
*bs
,
454 uint64_t offset
, uint64_t length
)
456 BDRVQcowState
*s
= bs
->opaque
;
457 Qcow2DiscardRegion
*d
, *p
, *next
;
459 QTAILQ_FOREACH(d
, &s
->discards
, next
) {
460 uint64_t new_start
= MIN(offset
, d
->offset
);
461 uint64_t new_end
= MAX(offset
+ length
, d
->offset
+ d
->bytes
);
463 if (new_end
- new_start
<= length
+ d
->bytes
) {
464 /* There can't be any overlap, areas ending up here have no
465 * references any more and therefore shouldn't get freed another
467 assert(d
->bytes
+ length
== new_end
- new_start
);
468 d
->offset
= new_start
;
469 d
->bytes
= new_end
- new_start
;
474 d
= g_malloc(sizeof(*d
));
475 *d
= (Qcow2DiscardRegion
) {
480 QTAILQ_INSERT_TAIL(&s
->discards
, d
, next
);
483 /* Merge discard requests if they are adjacent now */
484 QTAILQ_FOREACH_SAFE(p
, &s
->discards
, next
, next
) {
486 || p
->offset
> d
->offset
+ d
->bytes
487 || d
->offset
> p
->offset
+ p
->bytes
)
492 /* Still no overlap possible */
493 assert(p
->offset
== d
->offset
+ d
->bytes
494 || d
->offset
== p
->offset
+ p
->bytes
);
496 QTAILQ_REMOVE(&s
->discards
, p
, next
);
497 d
->offset
= MIN(d
->offset
, p
->offset
);
498 d
->bytes
+= p
->bytes
;
502 /* XXX: cache several refcount block clusters ? */
503 static int QEMU_WARN_UNUSED_RESULT
update_refcount(BlockDriverState
*bs
,
504 int64_t offset
, int64_t length
, int addend
, enum qcow2_discard_type type
)
506 BDRVQcowState
*s
= bs
->opaque
;
507 int64_t start
, last
, cluster_offset
;
508 uint16_t *refcount_block
= NULL
;
509 int64_t old_table_index
= -1;
513 fprintf(stderr
, "update_refcount: offset=%" PRId64
" size=%" PRId64
" addend=%d\n",
514 offset
, length
, addend
);
518 } else if (length
== 0) {
523 qcow2_cache_set_dependency(bs
, s
->refcount_block_cache
,
527 start
= start_of_cluster(s
, offset
);
528 last
= start_of_cluster(s
, offset
+ length
- 1);
529 for(cluster_offset
= start
; cluster_offset
<= last
;
530 cluster_offset
+= s
->cluster_size
)
532 int block_index
, refcount
;
533 int64_t cluster_index
= cluster_offset
>> s
->cluster_bits
;
534 int64_t table_index
=
535 cluster_index
>> (s
->cluster_bits
- REFCOUNT_SHIFT
);
537 /* Load the refcount block and allocate it if needed */
538 if (table_index
!= old_table_index
) {
539 if (refcount_block
) {
540 ret
= qcow2_cache_put(bs
, s
->refcount_block_cache
,
541 (void**) &refcount_block
);
547 ret
= alloc_refcount_block(bs
, cluster_index
, &refcount_block
);
552 old_table_index
= table_index
;
554 qcow2_cache_entry_mark_dirty(s
->refcount_block_cache
, refcount_block
);
556 /* we can update the count and save it */
557 block_index
= cluster_index
&
558 ((1 << (s
->cluster_bits
- REFCOUNT_SHIFT
)) - 1);
560 refcount
= be16_to_cpu(refcount_block
[block_index
]);
562 if (refcount
< 0 || refcount
> 0xffff) {
566 if (refcount
== 0 && cluster_index
< s
->free_cluster_index
) {
567 s
->free_cluster_index
= cluster_index
;
569 refcount_block
[block_index
] = cpu_to_be16(refcount
);
571 if (refcount
== 0 && s
->discard_passthrough
[type
]) {
572 update_refcount_discard(bs
, cluster_offset
, s
->cluster_size
);
578 if (!s
->cache_discards
) {
579 qcow2_process_discards(bs
, ret
);
582 /* Write last changed block to disk */
583 if (refcount_block
) {
585 wret
= qcow2_cache_put(bs
, s
->refcount_block_cache
,
586 (void**) &refcount_block
);
588 return ret
< 0 ? ret
: wret
;
593 * Try do undo any updates if an error is returned (This may succeed in
594 * some cases like ENOSPC for allocating a new refcount block)
598 dummy
= update_refcount(bs
, offset
, cluster_offset
- offset
, -addend
,
599 QCOW2_DISCARD_NEVER
);
607 * Increases or decreases the refcount of a given cluster by one.
608 * addend must be 1 or -1.
610 * If the return value is non-negative, it is the new refcount of the cluster.
611 * If it is negative, it is -errno and indicates an error.
613 int qcow2_update_cluster_refcount(BlockDriverState
*bs
,
614 int64_t cluster_index
,
616 enum qcow2_discard_type type
)
618 BDRVQcowState
*s
= bs
->opaque
;
621 ret
= update_refcount(bs
, cluster_index
<< s
->cluster_bits
, 1, addend
,
627 return get_refcount(bs
, cluster_index
);
632 /*********************************************************/
633 /* cluster allocation functions */
637 /* return < 0 if error */
638 static int64_t alloc_clusters_noref(BlockDriverState
*bs
, uint64_t size
)
640 BDRVQcowState
*s
= bs
->opaque
;
641 uint64_t i
, nb_clusters
;
644 nb_clusters
= size_to_clusters(s
, size
);
646 for(i
= 0; i
< nb_clusters
; i
++) {
647 uint64_t next_cluster_index
= s
->free_cluster_index
++;
648 refcount
= get_refcount(bs
, next_cluster_index
);
652 } else if (refcount
!= 0) {
657 /* Make sure that all offsets in the "allocated" range are representable
659 if (s
->free_cluster_index
- 1 > (INT64_MAX
>> s
->cluster_bits
)) {
664 fprintf(stderr
, "alloc_clusters: size=%" PRId64
" -> %" PRId64
"\n",
666 (s
->free_cluster_index
- nb_clusters
) << s
->cluster_bits
);
668 return (s
->free_cluster_index
- nb_clusters
) << s
->cluster_bits
;
671 int64_t qcow2_alloc_clusters(BlockDriverState
*bs
, uint64_t size
)
676 BLKDBG_EVENT(bs
->file
, BLKDBG_CLUSTER_ALLOC
);
678 offset
= alloc_clusters_noref(bs
, size
);
683 ret
= update_refcount(bs
, offset
, size
, 1, QCOW2_DISCARD_NEVER
);
684 } while (ret
== -EAGAIN
);
693 int qcow2_alloc_clusters_at(BlockDriverState
*bs
, uint64_t offset
,
696 BDRVQcowState
*s
= bs
->opaque
;
697 uint64_t cluster_index
;
701 assert(nb_clusters
>= 0);
702 if (nb_clusters
== 0) {
707 /* Check how many clusters there are free */
708 cluster_index
= offset
>> s
->cluster_bits
;
709 for(i
= 0; i
< nb_clusters
; i
++) {
710 refcount
= get_refcount(bs
, cluster_index
++);
714 } else if (refcount
!= 0) {
719 /* And then allocate them */
720 ret
= update_refcount(bs
, offset
, i
<< s
->cluster_bits
, 1,
721 QCOW2_DISCARD_NEVER
);
722 } while (ret
== -EAGAIN
);
731 /* only used to allocate compressed sectors. We try to allocate
732 contiguous sectors. size must be <= cluster_size */
733 int64_t qcow2_alloc_bytes(BlockDriverState
*bs
, int size
)
735 BDRVQcowState
*s
= bs
->opaque
;
736 int64_t offset
, cluster_offset
;
739 BLKDBG_EVENT(bs
->file
, BLKDBG_CLUSTER_ALLOC_BYTES
);
740 assert(size
> 0 && size
<= s
->cluster_size
);
741 if (s
->free_byte_offset
== 0) {
742 offset
= qcow2_alloc_clusters(bs
, s
->cluster_size
);
746 s
->free_byte_offset
= offset
;
749 free_in_cluster
= s
->cluster_size
-
750 offset_into_cluster(s
, s
->free_byte_offset
);
751 if (size
<= free_in_cluster
) {
752 /* enough space in current cluster */
753 offset
= s
->free_byte_offset
;
754 s
->free_byte_offset
+= size
;
755 free_in_cluster
-= size
;
756 if (free_in_cluster
== 0)
757 s
->free_byte_offset
= 0;
758 if (offset_into_cluster(s
, offset
) != 0)
759 qcow2_update_cluster_refcount(bs
, offset
>> s
->cluster_bits
, 1,
760 QCOW2_DISCARD_NEVER
);
762 offset
= qcow2_alloc_clusters(bs
, s
->cluster_size
);
766 cluster_offset
= start_of_cluster(s
, s
->free_byte_offset
);
767 if ((cluster_offset
+ s
->cluster_size
) == offset
) {
768 /* we are lucky: contiguous data */
769 offset
= s
->free_byte_offset
;
770 qcow2_update_cluster_refcount(bs
, offset
>> s
->cluster_bits
, 1,
771 QCOW2_DISCARD_NEVER
);
772 s
->free_byte_offset
+= size
;
774 s
->free_byte_offset
= offset
;
779 /* The cluster refcount was incremented, either by qcow2_alloc_clusters()
780 * or explicitly by qcow2_update_cluster_refcount(). Refcount blocks must
781 * be flushed before the caller's L2 table updates.
783 qcow2_cache_set_dependency(bs
, s
->l2_table_cache
, s
->refcount_block_cache
);
787 void qcow2_free_clusters(BlockDriverState
*bs
,
788 int64_t offset
, int64_t size
,
789 enum qcow2_discard_type type
)
793 BLKDBG_EVENT(bs
->file
, BLKDBG_CLUSTER_FREE
);
794 ret
= update_refcount(bs
, offset
, size
, -1, type
);
796 fprintf(stderr
, "qcow2_free_clusters failed: %s\n", strerror(-ret
));
797 /* TODO Remember the clusters to free them later and avoid leaking */
802 * Free a cluster using its L2 entry (handles clusters of all types, e.g.
803 * normal cluster, compressed cluster, etc.)
805 void qcow2_free_any_clusters(BlockDriverState
*bs
, uint64_t l2_entry
,
806 int nb_clusters
, enum qcow2_discard_type type
)
808 BDRVQcowState
*s
= bs
->opaque
;
810 switch (qcow2_get_cluster_type(l2_entry
)) {
811 case QCOW2_CLUSTER_COMPRESSED
:
814 nb_csectors
= ((l2_entry
>> s
->csize_shift
) &
816 qcow2_free_clusters(bs
,
817 (l2_entry
& s
->cluster_offset_mask
) & ~511,
818 nb_csectors
* 512, type
);
821 case QCOW2_CLUSTER_NORMAL
:
822 case QCOW2_CLUSTER_ZERO
:
823 if (l2_entry
& L2E_OFFSET_MASK
) {
824 qcow2_free_clusters(bs
, l2_entry
& L2E_OFFSET_MASK
,
825 nb_clusters
<< s
->cluster_bits
, type
);
828 case QCOW2_CLUSTER_UNALLOCATED
:
837 /*********************************************************/
838 /* snapshots and image creation */
842 /* update the refcounts of snapshots and the copied flag */
843 int qcow2_update_snapshot_refcount(BlockDriverState
*bs
,
844 int64_t l1_table_offset
, int l1_size
, int addend
)
846 BDRVQcowState
*s
= bs
->opaque
;
847 uint64_t *l1_table
, *l2_table
, l2_offset
, offset
, l1_size2
, l1_allocated
;
848 int64_t old_offset
, old_l2_offset
;
849 int i
, j
, l1_modified
= 0, nb_csectors
, refcount
;
854 l1_size2
= l1_size
* sizeof(uint64_t);
856 s
->cache_discards
= true;
858 /* WARNING: qcow2_snapshot_goto relies on this function not using the
859 * l1_table_offset when it is the current s->l1_table_offset! Be careful
860 * when changing this! */
861 if (l1_table_offset
!= s
->l1_table_offset
) {
862 l1_table
= g_malloc0(align_offset(l1_size2
, 512));
865 ret
= bdrv_pread(bs
->file
, l1_table_offset
, l1_table
, l1_size2
);
870 for(i
= 0;i
< l1_size
; i
++)
871 be64_to_cpus(&l1_table
[i
]);
873 assert(l1_size
== s
->l1_size
);
874 l1_table
= s
->l1_table
;
878 for(i
= 0; i
< l1_size
; i
++) {
879 l2_offset
= l1_table
[i
];
881 old_l2_offset
= l2_offset
;
882 l2_offset
&= L1E_OFFSET_MASK
;
884 ret
= qcow2_cache_get(bs
, s
->l2_table_cache
, l2_offset
,
890 for(j
= 0; j
< s
->l2_size
; j
++) {
891 uint64_t cluster_index
;
893 offset
= be64_to_cpu(l2_table
[j
]);
895 offset
&= ~QCOW_OFLAG_COPIED
;
897 switch (qcow2_get_cluster_type(offset
)) {
898 case QCOW2_CLUSTER_COMPRESSED
:
899 nb_csectors
= ((offset
>> s
->csize_shift
) &
902 ret
= update_refcount(bs
,
903 (offset
& s
->cluster_offset_mask
) & ~511,
904 nb_csectors
* 512, addend
,
905 QCOW2_DISCARD_SNAPSHOT
);
910 /* compressed clusters are never modified */
914 case QCOW2_CLUSTER_NORMAL
:
915 case QCOW2_CLUSTER_ZERO
:
916 cluster_index
= (offset
& L2E_OFFSET_MASK
) >> s
->cluster_bits
;
917 if (!cluster_index
) {
923 refcount
= qcow2_update_cluster_refcount(bs
,
924 cluster_index
, addend
,
925 QCOW2_DISCARD_SNAPSHOT
);
927 refcount
= get_refcount(bs
, cluster_index
);
936 case QCOW2_CLUSTER_UNALLOCATED
:
945 offset
|= QCOW_OFLAG_COPIED
;
947 if (offset
!= old_offset
) {
949 qcow2_cache_set_dependency(bs
, s
->l2_table_cache
,
950 s
->refcount_block_cache
);
952 l2_table
[j
] = cpu_to_be64(offset
);
953 qcow2_cache_entry_mark_dirty(s
->l2_table_cache
, l2_table
);
957 ret
= qcow2_cache_put(bs
, s
->l2_table_cache
, (void**) &l2_table
);
964 refcount
= qcow2_update_cluster_refcount(bs
, l2_offset
>>
965 s
->cluster_bits
, addend
, QCOW2_DISCARD_SNAPSHOT
);
967 refcount
= get_refcount(bs
, l2_offset
>> s
->cluster_bits
);
972 } else if (refcount
== 1) {
973 l2_offset
|= QCOW_OFLAG_COPIED
;
975 if (l2_offset
!= old_l2_offset
) {
976 l1_table
[i
] = l2_offset
;
982 ret
= bdrv_flush(bs
);
985 qcow2_cache_put(bs
, s
->l2_table_cache
, (void**) &l2_table
);
988 s
->cache_discards
= false;
989 qcow2_process_discards(bs
, ret
);
991 /* Update L1 only if it isn't deleted anyway (addend = -1) */
992 if (ret
== 0 && addend
>= 0 && l1_modified
) {
993 for (i
= 0; i
< l1_size
; i
++) {
994 cpu_to_be64s(&l1_table
[i
]);
997 ret
= bdrv_pwrite_sync(bs
->file
, l1_table_offset
, l1_table
, l1_size2
);
999 for (i
= 0; i
< l1_size
; i
++) {
1000 be64_to_cpus(&l1_table
[i
]);
1011 /*********************************************************/
1012 /* refcount checking functions */
1017 * Increases the refcount for a range of clusters in a given refcount table.
1018 * This is used to construct a temporary refcount table out of L1 and L2 tables
1019 * which can be compared the the refcount table saved in the image.
1021 * Modifies the number of errors in res.
1023 static void inc_refcounts(BlockDriverState
*bs
,
1024 BdrvCheckResult
*res
,
1025 uint16_t *refcount_table
,
1026 int refcount_table_size
,
1027 int64_t offset
, int64_t size
)
1029 BDRVQcowState
*s
= bs
->opaque
;
1030 uint64_t start
, last
, cluster_offset
, k
;
1035 start
= start_of_cluster(s
, offset
);
1036 last
= start_of_cluster(s
, offset
+ size
- 1);
1037 for(cluster_offset
= start
; cluster_offset
<= last
;
1038 cluster_offset
+= s
->cluster_size
) {
1039 k
= cluster_offset
>> s
->cluster_bits
;
1040 if (k
>= refcount_table_size
) {
1041 fprintf(stderr
, "Warning: cluster offset=0x%" PRIx64
" is after "
1042 "the end of the image file, can't properly check refcounts.\n",
1044 res
->check_errors
++;
1046 if (++refcount_table
[k
] == 0) {
1047 fprintf(stderr
, "ERROR: overflow cluster offset=0x%" PRIx64
1048 "\n", cluster_offset
);
1055 /* Flags for check_refcounts_l1() and check_refcounts_l2() */
1057 CHECK_FRAG_INFO
= 0x2, /* update BlockFragInfo counters */
1061 * Increases the refcount in the given refcount table for the all clusters
1062 * referenced in the L2 table. While doing so, performs some checks on L2
1065 * Returns the number of errors found by the checks or -errno if an internal
1068 static int check_refcounts_l2(BlockDriverState
*bs
, BdrvCheckResult
*res
,
1069 uint16_t *refcount_table
, int refcount_table_size
, int64_t l2_offset
,
1072 BDRVQcowState
*s
= bs
->opaque
;
1073 uint64_t *l2_table
, l2_entry
;
1074 uint64_t next_contiguous_offset
= 0;
1075 int i
, l2_size
, nb_csectors
;
1077 /* Read L2 table from disk */
1078 l2_size
= s
->l2_size
* sizeof(uint64_t);
1079 l2_table
= g_malloc(l2_size
);
1081 if (bdrv_pread(bs
->file
, l2_offset
, l2_table
, l2_size
) != l2_size
)
1084 /* Do the actual checks */
1085 for(i
= 0; i
< s
->l2_size
; i
++) {
1086 l2_entry
= be64_to_cpu(l2_table
[i
]);
1088 switch (qcow2_get_cluster_type(l2_entry
)) {
1089 case QCOW2_CLUSTER_COMPRESSED
:
1090 /* Compressed clusters don't have QCOW_OFLAG_COPIED */
1091 if (l2_entry
& QCOW_OFLAG_COPIED
) {
1092 fprintf(stderr
, "ERROR: cluster %" PRId64
": "
1093 "copied flag must never be set for compressed "
1094 "clusters\n", l2_entry
>> s
->cluster_bits
);
1095 l2_entry
&= ~QCOW_OFLAG_COPIED
;
1099 /* Mark cluster as used */
1100 nb_csectors
= ((l2_entry
>> s
->csize_shift
) &
1102 l2_entry
&= s
->cluster_offset_mask
;
1103 inc_refcounts(bs
, res
, refcount_table
, refcount_table_size
,
1104 l2_entry
& ~511, nb_csectors
* 512);
1106 if (flags
& CHECK_FRAG_INFO
) {
1107 res
->bfi
.allocated_clusters
++;
1108 res
->bfi
.compressed_clusters
++;
1110 /* Compressed clusters are fragmented by nature. Since they
1111 * take up sub-sector space but we only have sector granularity
1112 * I/O we need to re-read the same sectors even for adjacent
1113 * compressed clusters.
1115 res
->bfi
.fragmented_clusters
++;
1119 case QCOW2_CLUSTER_ZERO
:
1120 if ((l2_entry
& L2E_OFFSET_MASK
) == 0) {
1125 case QCOW2_CLUSTER_NORMAL
:
1127 uint64_t offset
= l2_entry
& L2E_OFFSET_MASK
;
1129 if (flags
& CHECK_FRAG_INFO
) {
1130 res
->bfi
.allocated_clusters
++;
1131 if (next_contiguous_offset
&&
1132 offset
!= next_contiguous_offset
) {
1133 res
->bfi
.fragmented_clusters
++;
1135 next_contiguous_offset
= offset
+ s
->cluster_size
;
1138 /* Mark cluster as used */
1139 inc_refcounts(bs
, res
, refcount_table
,refcount_table_size
,
1140 offset
, s
->cluster_size
);
1142 /* Correct offsets are cluster aligned */
1143 if (offset_into_cluster(s
, offset
)) {
1144 fprintf(stderr
, "ERROR offset=%" PRIx64
": Cluster is not "
1145 "properly aligned; L2 entry corrupted.\n", offset
);
1151 case QCOW2_CLUSTER_UNALLOCATED
:
1163 fprintf(stderr
, "ERROR: I/O error in check_refcounts_l2\n");
1169 * Increases the refcount for the L1 table, its L2 tables and all referenced
1170 * clusters in the given refcount table. While doing so, performs some checks
1171 * on L1 and L2 entries.
1173 * Returns the number of errors found by the checks or -errno if an internal
1176 static int check_refcounts_l1(BlockDriverState
*bs
,
1177 BdrvCheckResult
*res
,
1178 uint16_t *refcount_table
,
1179 int refcount_table_size
,
1180 int64_t l1_table_offset
, int l1_size
,
1183 BDRVQcowState
*s
= bs
->opaque
;
1184 uint64_t *l1_table
, l2_offset
, l1_size2
;
1187 l1_size2
= l1_size
* sizeof(uint64_t);
1189 /* Mark L1 table as used */
1190 inc_refcounts(bs
, res
, refcount_table
, refcount_table_size
,
1191 l1_table_offset
, l1_size2
);
1193 /* Read L1 table entries from disk */
1194 if (l1_size2
== 0) {
1197 l1_table
= g_malloc(l1_size2
);
1198 if (bdrv_pread(bs
->file
, l1_table_offset
,
1199 l1_table
, l1_size2
) != l1_size2
)
1201 for(i
= 0;i
< l1_size
; i
++)
1202 be64_to_cpus(&l1_table
[i
]);
1205 /* Do the actual checks */
1206 for(i
= 0; i
< l1_size
; i
++) {
1207 l2_offset
= l1_table
[i
];
1209 /* Mark L2 table as used */
1210 l2_offset
&= L1E_OFFSET_MASK
;
1211 inc_refcounts(bs
, res
, refcount_table
, refcount_table_size
,
1212 l2_offset
, s
->cluster_size
);
1214 /* L2 tables are cluster aligned */
1215 if (offset_into_cluster(s
, l2_offset
)) {
1216 fprintf(stderr
, "ERROR l2_offset=%" PRIx64
": Table is not "
1217 "cluster aligned; L1 entry corrupted\n", l2_offset
);
1221 /* Process and check L2 entries */
1222 ret
= check_refcounts_l2(bs
, res
, refcount_table
,
1223 refcount_table_size
, l2_offset
, flags
);
1233 fprintf(stderr
, "ERROR: I/O error in check_refcounts_l1\n");
1234 res
->check_errors
++;
1240 * Checks the OFLAG_COPIED flag for all L1 and L2 entries.
1242 * This function does not print an error message nor does it increment
1243 * check_errors if get_refcount fails (this is because such an error will have
1244 * been already detected and sufficiently signaled by the calling function
1245 * (qcow2_check_refcounts) by the time this function is called).
1247 static int check_oflag_copied(BlockDriverState
*bs
, BdrvCheckResult
*res
,
1250 BDRVQcowState
*s
= bs
->opaque
;
1251 uint64_t *l2_table
= qemu_blockalign(bs
, s
->cluster_size
);
1256 for (i
= 0; i
< s
->l1_size
; i
++) {
1257 uint64_t l1_entry
= s
->l1_table
[i
];
1258 uint64_t l2_offset
= l1_entry
& L1E_OFFSET_MASK
;
1259 bool l2_dirty
= false;
1265 refcount
= get_refcount(bs
, l2_offset
>> s
->cluster_bits
);
1267 /* don't print message nor increment check_errors */
1270 if ((refcount
== 1) != ((l1_entry
& QCOW_OFLAG_COPIED
) != 0)) {
1271 fprintf(stderr
, "%s OFLAG_COPIED L2 cluster: l1_index=%d "
1272 "l1_entry=%" PRIx64
" refcount=%d\n",
1273 fix
& BDRV_FIX_ERRORS
? "Repairing" :
1275 i
, l1_entry
, refcount
);
1276 if (fix
& BDRV_FIX_ERRORS
) {
1277 s
->l1_table
[i
] = refcount
== 1
1278 ? l1_entry
| QCOW_OFLAG_COPIED
1279 : l1_entry
& ~QCOW_OFLAG_COPIED
;
1280 ret
= qcow2_write_l1_entry(bs
, i
);
1282 res
->check_errors
++;
1285 res
->corruptions_fixed
++;
1291 ret
= bdrv_pread(bs
->file
, l2_offset
, l2_table
,
1292 s
->l2_size
* sizeof(uint64_t));
1294 fprintf(stderr
, "ERROR: Could not read L2 table: %s\n",
1296 res
->check_errors
++;
1300 for (j
= 0; j
< s
->l2_size
; j
++) {
1301 uint64_t l2_entry
= be64_to_cpu(l2_table
[j
]);
1302 uint64_t data_offset
= l2_entry
& L2E_OFFSET_MASK
;
1303 int cluster_type
= qcow2_get_cluster_type(l2_entry
);
1305 if ((cluster_type
== QCOW2_CLUSTER_NORMAL
) ||
1306 ((cluster_type
== QCOW2_CLUSTER_ZERO
) && (data_offset
!= 0))) {
1307 refcount
= get_refcount(bs
, data_offset
>> s
->cluster_bits
);
1309 /* don't print message nor increment check_errors */
1312 if ((refcount
== 1) != ((l2_entry
& QCOW_OFLAG_COPIED
) != 0)) {
1313 fprintf(stderr
, "%s OFLAG_COPIED data cluster: "
1314 "l2_entry=%" PRIx64
" refcount=%d\n",
1315 fix
& BDRV_FIX_ERRORS
? "Repairing" :
1317 l2_entry
, refcount
);
1318 if (fix
& BDRV_FIX_ERRORS
) {
1319 l2_table
[j
] = cpu_to_be64(refcount
== 1
1320 ? l2_entry
| QCOW_OFLAG_COPIED
1321 : l2_entry
& ~QCOW_OFLAG_COPIED
);
1323 res
->corruptions_fixed
++;
1332 ret
= qcow2_pre_write_overlap_check(bs
, QCOW2_OL_ACTIVE_L2
,
1333 l2_offset
, s
->cluster_size
);
1335 fprintf(stderr
, "ERROR: Could not write L2 table; metadata "
1336 "overlap check failed: %s\n", strerror(-ret
));
1337 res
->check_errors
++;
1341 ret
= bdrv_pwrite(bs
->file
, l2_offset
, l2_table
, s
->cluster_size
);
1343 fprintf(stderr
, "ERROR: Could not write L2 table: %s\n",
1345 res
->check_errors
++;
1354 qemu_vfree(l2_table
);
1359 * Writes one sector of the refcount table to the disk
1361 #define RT_ENTRIES_PER_SECTOR (512 / sizeof(uint64_t))
1362 static int write_reftable_entry(BlockDriverState
*bs
, int rt_index
)
1364 BDRVQcowState
*s
= bs
->opaque
;
1365 uint64_t buf
[RT_ENTRIES_PER_SECTOR
];
1369 rt_start_index
= rt_index
& ~(RT_ENTRIES_PER_SECTOR
- 1);
1370 for (i
= 0; i
< RT_ENTRIES_PER_SECTOR
; i
++) {
1371 buf
[i
] = cpu_to_be64(s
->refcount_table
[rt_start_index
+ i
]);
1374 ret
= qcow2_pre_write_overlap_check(bs
, QCOW2_OL_REFCOUNT_TABLE
,
1375 s
->refcount_table_offset
+ rt_start_index
* sizeof(uint64_t),
1381 BLKDBG_EVENT(bs
->file
, BLKDBG_REFTABLE_UPDATE
);
1382 ret
= bdrv_pwrite_sync(bs
->file
, s
->refcount_table_offset
+
1383 rt_start_index
* sizeof(uint64_t), buf
, sizeof(buf
));
1392 * Allocates a new cluster for the given refcount block (represented by its
1393 * offset in the image file) and copies the current content there. This function
1394 * does _not_ decrement the reference count for the currently occupied cluster.
1396 * This function prints an informative message to stderr on error (and returns
1397 * -errno); on success, the offset of the newly allocated cluster is returned.
1399 static int64_t realloc_refcount_block(BlockDriverState
*bs
, int reftable_index
,
1402 BDRVQcowState
*s
= bs
->opaque
;
1403 int64_t new_offset
= 0;
1404 void *refcount_block
= NULL
;
1407 /* allocate new refcount block */
1408 new_offset
= qcow2_alloc_clusters(bs
, s
->cluster_size
);
1409 if (new_offset
< 0) {
1410 fprintf(stderr
, "Could not allocate new cluster: %s\n",
1411 strerror(-new_offset
));
1416 /* fetch current refcount block content */
1417 ret
= qcow2_cache_get(bs
, s
->refcount_block_cache
, offset
, &refcount_block
);
1419 fprintf(stderr
, "Could not fetch refcount block: %s\n", strerror(-ret
));
1420 goto fail_free_cluster
;
1423 /* new block has not yet been entered into refcount table, therefore it is
1424 * no refcount block yet (regarding this check) */
1425 ret
= qcow2_pre_write_overlap_check(bs
, 0, new_offset
, s
->cluster_size
);
1427 fprintf(stderr
, "Could not write refcount block; metadata overlap "
1428 "check failed: %s\n", strerror(-ret
));
1429 /* the image will be marked corrupt, so don't even attempt on freeing
1434 /* write to new block */
1435 ret
= bdrv_write(bs
->file
, new_offset
/ BDRV_SECTOR_SIZE
, refcount_block
,
1436 s
->cluster_sectors
);
1438 fprintf(stderr
, "Could not write refcount block: %s\n", strerror(-ret
));
1439 goto fail_free_cluster
;
1442 /* update refcount table */
1443 assert(!offset_into_cluster(s
, new_offset
));
1444 s
->refcount_table
[reftable_index
] = new_offset
;
1445 ret
= write_reftable_entry(bs
, reftable_index
);
1447 fprintf(stderr
, "Could not update refcount table: %s\n",
1449 goto fail_free_cluster
;
1455 qcow2_free_clusters(bs
, new_offset
, s
->cluster_size
, QCOW2_DISCARD_OTHER
);
1458 if (refcount_block
) {
1459 /* This should never fail, as it would only do so if the given refcount
1460 * block cannot be found in the cache. As this is impossible as long as
1461 * there are no bugs, assert the success. */
1462 int tmp
= qcow2_cache_put(bs
, s
->refcount_block_cache
, &refcount_block
);
1474 * Checks an image for refcount consistency.
1476 * Returns 0 if no errors are found, the number of errors in case the image is
1477 * detected as corrupted, and -errno when an internal error occurred.
1479 int qcow2_check_refcounts(BlockDriverState
*bs
, BdrvCheckResult
*res
,
1482 BDRVQcowState
*s
= bs
->opaque
;
1483 int64_t size
, i
, highest_cluster
, nb_clusters
;
1484 int refcount1
, refcount2
;
1486 uint16_t *refcount_table
;
1489 size
= bdrv_getlength(bs
->file
);
1491 res
->check_errors
++;
1495 nb_clusters
= size_to_clusters(s
, size
);
1496 if (nb_clusters
> INT_MAX
) {
1497 res
->check_errors
++;
1501 refcount_table
= g_malloc0(nb_clusters
* sizeof(uint16_t));
1503 res
->bfi
.total_clusters
=
1504 size_to_clusters(s
, bs
->total_sectors
* BDRV_SECTOR_SIZE
);
1507 inc_refcounts(bs
, res
, refcount_table
, nb_clusters
,
1508 0, s
->cluster_size
);
1510 /* current L1 table */
1511 ret
= check_refcounts_l1(bs
, res
, refcount_table
, nb_clusters
,
1512 s
->l1_table_offset
, s
->l1_size
, CHECK_FRAG_INFO
);
1518 for(i
= 0; i
< s
->nb_snapshots
; i
++) {
1519 sn
= s
->snapshots
+ i
;
1520 ret
= check_refcounts_l1(bs
, res
, refcount_table
, nb_clusters
,
1521 sn
->l1_table_offset
, sn
->l1_size
, 0);
1526 inc_refcounts(bs
, res
, refcount_table
, nb_clusters
,
1527 s
->snapshots_offset
, s
->snapshots_size
);
1530 inc_refcounts(bs
, res
, refcount_table
, nb_clusters
,
1531 s
->refcount_table_offset
,
1532 s
->refcount_table_size
* sizeof(uint64_t));
1534 for(i
= 0; i
< s
->refcount_table_size
; i
++) {
1535 uint64_t offset
, cluster
;
1536 offset
= s
->refcount_table
[i
];
1537 cluster
= offset
>> s
->cluster_bits
;
1539 /* Refcount blocks are cluster aligned */
1540 if (offset_into_cluster(s
, offset
)) {
1541 fprintf(stderr
, "ERROR refcount block %" PRId64
" is not "
1542 "cluster aligned; refcount table entry corrupted\n", i
);
1547 if (cluster
>= nb_clusters
) {
1548 fprintf(stderr
, "ERROR refcount block %" PRId64
1549 " is outside image\n", i
);
1555 inc_refcounts(bs
, res
, refcount_table
, nb_clusters
,
1556 offset
, s
->cluster_size
);
1557 if (refcount_table
[cluster
] != 1) {
1558 fprintf(stderr
, "%s refcount block %" PRId64
1560 fix
& BDRV_FIX_ERRORS
? "Repairing" :
1562 i
, refcount_table
[cluster
]);
1564 if (fix
& BDRV_FIX_ERRORS
) {
1567 new_offset
= realloc_refcount_block(bs
, i
, offset
);
1568 if (new_offset
< 0) {
1573 /* update refcounts */
1574 if ((new_offset
>> s
->cluster_bits
) >= nb_clusters
) {
1575 /* increase refcount_table size if necessary */
1576 int old_nb_clusters
= nb_clusters
;
1577 nb_clusters
= (new_offset
>> s
->cluster_bits
) + 1;
1578 refcount_table
= g_realloc(refcount_table
,
1579 nb_clusters
* sizeof(uint16_t));
1580 memset(&refcount_table
[old_nb_clusters
], 0, (nb_clusters
1581 - old_nb_clusters
) * sizeof(uint16_t));
1583 refcount_table
[cluster
]--;
1584 inc_refcounts(bs
, res
, refcount_table
, nb_clusters
,
1585 new_offset
, s
->cluster_size
);
1587 res
->corruptions_fixed
++;
1595 /* compare ref counts */
1596 for (i
= 0, highest_cluster
= 0; i
< nb_clusters
; i
++) {
1597 refcount1
= get_refcount(bs
, i
);
1598 if (refcount1
< 0) {
1599 fprintf(stderr
, "Can't get refcount for cluster %" PRId64
": %s\n",
1600 i
, strerror(-refcount1
));
1601 res
->check_errors
++;
1605 refcount2
= refcount_table
[i
];
1607 if (refcount1
> 0 || refcount2
> 0) {
1608 highest_cluster
= i
;
1611 if (refcount1
!= refcount2
) {
1613 /* Check if we're allowed to fix the mismatch */
1614 int *num_fixed
= NULL
;
1615 if (refcount1
> refcount2
&& (fix
& BDRV_FIX_LEAKS
)) {
1616 num_fixed
= &res
->leaks_fixed
;
1617 } else if (refcount1
< refcount2
&& (fix
& BDRV_FIX_ERRORS
)) {
1618 num_fixed
= &res
->corruptions_fixed
;
1621 fprintf(stderr
, "%s cluster %" PRId64
" refcount=%d reference=%d\n",
1622 num_fixed
!= NULL
? "Repairing" :
1623 refcount1
< refcount2
? "ERROR" :
1625 i
, refcount1
, refcount2
);
1628 ret
= update_refcount(bs
, i
<< s
->cluster_bits
, 1,
1629 refcount2
- refcount1
,
1630 QCOW2_DISCARD_ALWAYS
);
1637 /* And if we couldn't, print an error */
1638 if (refcount1
< refcount2
) {
1646 /* check OFLAG_COPIED */
1647 ret
= check_oflag_copied(bs
, res
, fix
);
1652 res
->image_end_offset
= (highest_cluster
+ 1) * s
->cluster_size
;
1656 g_free(refcount_table
);
1661 #define overlaps_with(ofs, sz) \
1662 ranges_overlap(offset, size, ofs, sz)
1665 * Checks if the given offset into the image file is actually free to use by
1666 * looking for overlaps with important metadata sections (L1/L2 tables etc.),
1667 * i.e. a sanity check without relying on the refcount tables.
1669 * The ign parameter specifies what checks not to perform (being a bitmask of
1670 * QCow2MetadataOverlap values), i.e., what sections to ignore.
1673 * - 0 if writing to this offset will not affect the mentioned metadata
1674 * - a positive QCow2MetadataOverlap value indicating one overlapping section
1675 * - a negative value (-errno) indicating an error while performing a check,
1676 * e.g. when bdrv_read failed on QCOW2_OL_INACTIVE_L2
1678 int qcow2_check_metadata_overlap(BlockDriverState
*bs
, int ign
, int64_t offset
,
1681 BDRVQcowState
*s
= bs
->opaque
;
1682 int chk
= s
->overlap_check
& ~ign
;
1689 if (chk
& QCOW2_OL_MAIN_HEADER
) {
1690 if (offset
< s
->cluster_size
) {
1691 return QCOW2_OL_MAIN_HEADER
;
1695 /* align range to test to cluster boundaries */
1696 size
= align_offset(offset_into_cluster(s
, offset
) + size
, s
->cluster_size
);
1697 offset
= start_of_cluster(s
, offset
);
1699 if ((chk
& QCOW2_OL_ACTIVE_L1
) && s
->l1_size
) {
1700 if (overlaps_with(s
->l1_table_offset
, s
->l1_size
* sizeof(uint64_t))) {
1701 return QCOW2_OL_ACTIVE_L1
;
1705 if ((chk
& QCOW2_OL_REFCOUNT_TABLE
) && s
->refcount_table_size
) {
1706 if (overlaps_with(s
->refcount_table_offset
,
1707 s
->refcount_table_size
* sizeof(uint64_t))) {
1708 return QCOW2_OL_REFCOUNT_TABLE
;
1712 if ((chk
& QCOW2_OL_SNAPSHOT_TABLE
) && s
->snapshots_size
) {
1713 if (overlaps_with(s
->snapshots_offset
, s
->snapshots_size
)) {
1714 return QCOW2_OL_SNAPSHOT_TABLE
;
1718 if ((chk
& QCOW2_OL_INACTIVE_L1
) && s
->snapshots
) {
1719 for (i
= 0; i
< s
->nb_snapshots
; i
++) {
1720 if (s
->snapshots
[i
].l1_size
&&
1721 overlaps_with(s
->snapshots
[i
].l1_table_offset
,
1722 s
->snapshots
[i
].l1_size
* sizeof(uint64_t))) {
1723 return QCOW2_OL_INACTIVE_L1
;
1728 if ((chk
& QCOW2_OL_ACTIVE_L2
) && s
->l1_table
) {
1729 for (i
= 0; i
< s
->l1_size
; i
++) {
1730 if ((s
->l1_table
[i
] & L1E_OFFSET_MASK
) &&
1731 overlaps_with(s
->l1_table
[i
] & L1E_OFFSET_MASK
,
1733 return QCOW2_OL_ACTIVE_L2
;
1738 if ((chk
& QCOW2_OL_REFCOUNT_BLOCK
) && s
->refcount_table
) {
1739 for (i
= 0; i
< s
->refcount_table_size
; i
++) {
1740 if ((s
->refcount_table
[i
] & REFT_OFFSET_MASK
) &&
1741 overlaps_with(s
->refcount_table
[i
] & REFT_OFFSET_MASK
,
1743 return QCOW2_OL_REFCOUNT_BLOCK
;
1748 if ((chk
& QCOW2_OL_INACTIVE_L2
) && s
->snapshots
) {
1749 for (i
= 0; i
< s
->nb_snapshots
; i
++) {
1750 uint64_t l1_ofs
= s
->snapshots
[i
].l1_table_offset
;
1751 uint32_t l1_sz
= s
->snapshots
[i
].l1_size
;
1752 uint64_t l1_sz2
= l1_sz
* sizeof(uint64_t);
1753 uint64_t *l1
= g_malloc(l1_sz2
);
1756 ret
= bdrv_pread(bs
->file
, l1_ofs
, l1
, l1_sz2
);
1762 for (j
= 0; j
< l1_sz
; j
++) {
1763 uint64_t l2_ofs
= be64_to_cpu(l1
[j
]) & L1E_OFFSET_MASK
;
1764 if (l2_ofs
&& overlaps_with(l2_ofs
, s
->cluster_size
)) {
1766 return QCOW2_OL_INACTIVE_L2
;
1777 static const char *metadata_ol_names
[] = {
1778 [QCOW2_OL_MAIN_HEADER_BITNR
] = "qcow2_header",
1779 [QCOW2_OL_ACTIVE_L1_BITNR
] = "active L1 table",
1780 [QCOW2_OL_ACTIVE_L2_BITNR
] = "active L2 table",
1781 [QCOW2_OL_REFCOUNT_TABLE_BITNR
] = "refcount table",
1782 [QCOW2_OL_REFCOUNT_BLOCK_BITNR
] = "refcount block",
1783 [QCOW2_OL_SNAPSHOT_TABLE_BITNR
] = "snapshot table",
1784 [QCOW2_OL_INACTIVE_L1_BITNR
] = "inactive L1 table",
1785 [QCOW2_OL_INACTIVE_L2_BITNR
] = "inactive L2 table",
1789 * First performs a check for metadata overlaps (through
1790 * qcow2_check_metadata_overlap); if that fails with a negative value (error
1791 * while performing a check), that value is returned. If an impending overlap
1792 * is detected, the BDS will be made unusable, the qcow2 file marked corrupt
1793 * and -EIO returned.
1795 * Returns 0 if there were neither overlaps nor errors while checking for
1796 * overlaps; or a negative value (-errno) on error.
1798 int qcow2_pre_write_overlap_check(BlockDriverState
*bs
, int ign
, int64_t offset
,
1801 int ret
= qcow2_check_metadata_overlap(bs
, ign
, offset
, size
);
1805 } else if (ret
> 0) {
1806 int metadata_ol_bitnr
= ffs(ret
) - 1;
1810 assert(metadata_ol_bitnr
< QCOW2_OL_MAX_BITNR
);
1812 fprintf(stderr
, "qcow2: Preventing invalid write on metadata (overlaps "
1813 "with %s); image marked as corrupt.\n",
1814 metadata_ol_names
[metadata_ol_bitnr
]);
1815 message
= g_strdup_printf("Prevented %s overwrite",
1816 metadata_ol_names
[metadata_ol_bitnr
]);
1817 data
= qobject_from_jsonf("{ 'device': %s, 'msg': %s, 'offset': %"
1818 PRId64
", 'size': %" PRId64
" }", bs
->device_name
, message
,
1820 monitor_protocol_event(QEVENT_BLOCK_IMAGE_CORRUPTED
, data
);
1822 qobject_decref(data
);
1824 qcow2_mark_corrupt(bs
);
1825 bs
->drv
= NULL
; /* make BDS unusable */