Offset 0 can be valid for normal (allocated) clusters now, so use
qcow2_get_cluster_type() instead.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/qcow2-cluster.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index 9cc8f0f3e4..660161bf00 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -389,12 +389,12 @@ static int count_contiguous_clusters(BlockDriverState *bs, int nb_clusters,
     uint64_t first_entry = be64_to_cpu(l2_slice[0]);
     uint64_t offset = first_entry & mask;
 
-    if (!offset) {
+    first_cluster_type = qcow2_get_cluster_type(bs, first_entry);
+    if (first_cluster_type == QCOW2_CLUSTER_UNALLOCATED) {
         return 0;
     }
 
     /* must be allocated */
-    first_cluster_type = qcow2_get_cluster_type(bs, first_entry);
     assert(first_cluster_type == QCOW2_CLUSTER_NORMAL ||
            first_cluster_type == QCOW2_CLUSTER_ZERO_ALLOC);
 
-- 
2.20.1