Refblock allocation code needs to take into consideration that update_refcount
will load a different refcount block into the cache, so it must initialize the
cache for a new refcount block only afterwards. Not doing this means that not
only the refcount in the wrong block is updated, but also that the caller will
work on the wrong block.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit
25408c09502be036e5575754fe54019ed4ed5dfa)
/* Allocate the refcount block itself and mark it as used */
uint64_t new_block = alloc_clusters_noref(bs, s->cluster_size);
/* Allocate the refcount block itself and mark it as used */
uint64_t new_block = alloc_clusters_noref(bs, s->cluster_size);
- memset(s->refcount_block_cache, 0, s->cluster_size);
- s->refcount_block_cache_offset = new_block;
#ifdef DEBUG_ALLOC2
fprintf(stderr, "qcow2: Allocate refcount block %d for %" PRIx64
#ifdef DEBUG_ALLOC2
fprintf(stderr, "qcow2: Allocate refcount block %d for %" PRIx64
#endif
if (in_same_refcount_block(s, new_block, cluster_index << s->cluster_bits)) {
#endif
if (in_same_refcount_block(s, new_block, cluster_index << s->cluster_bits)) {
+ /* Zero the new refcount block before updating it */
+ memset(s->refcount_block_cache, 0, s->cluster_size);
+ s->refcount_block_cache_offset = new_block;
+
/* The block describes itself, need to update the cache */
int block_index = (new_block >> s->cluster_bits) &
((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1);
/* The block describes itself, need to update the cache */
int block_index = (new_block >> s->cluster_bits) &
((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1);
if (ret < 0) {
goto fail_block;
}
if (ret < 0) {
goto fail_block;
}
+
+ /* Initialize the new refcount block only after updating its refcount,
+ * update_refcount uses the refcount cache itself */
+ memset(s->refcount_block_cache, 0, s->cluster_size);
+ s->refcount_block_cache_offset = new_block;
}
/* Now the new refcount block needs to be written to disk */
}
/* Now the new refcount block needs to be written to disk */