diff options
| -rw-r--r-- | block/qcow2-refcount.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c index 5ebbcb63d..fa78e46ee 100644 --- a/block/qcow2-refcount.c +++ b/block/qcow2-refcount.c @@ -215,8 +215,6 @@ static int64_t alloc_refcount_block(BlockDriverState *bs, int64_t cluster_index) /* 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 @@ -225,6 +223,10 @@ static int64_t alloc_refcount_block(BlockDriverState *bs, int64_t cluster_index) #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); @@ -236,6 +238,11 @@ static int64_t alloc_refcount_block(BlockDriverState *bs, int64_t cluster_index) 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 */ |