From: Alberto Garcia <berto@igalia.com>

We are going to need it in other places.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <65e5d9627ca2ebe7e62deaeddf60949c33067d9d.1594396418.git.berto@igalia.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block/qcow2-cluster.c | 34 +++++++++++++++++++---------------
 1 file changed, 19 insertions(+), 15 deletions(-)

diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index 6447222ba0..369689b27c 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -1088,6 +1088,24 @@ static void calculate_l2_meta(BlockDriverState *bs,
     QLIST_INSERT_HEAD(&s->cluster_allocs, *m, next_in_flight);
 }
 
+/* Returns true if writing to a cluster requires COW */
+static bool cluster_needs_cow(BlockDriverState *bs, uint64_t l2_entry)
+{
+    switch (qcow2_get_cluster_type(bs, l2_entry)) {
+    case QCOW2_CLUSTER_NORMAL:
+        if (l2_entry & QCOW_OFLAG_COPIED) {
+            return false;
+        }
+    case QCOW2_CLUSTER_UNALLOCATED:
+    case QCOW2_CLUSTER_COMPRESSED:
+    case QCOW2_CLUSTER_ZERO_PLAIN:
+    case QCOW2_CLUSTER_ZERO_ALLOC:
+        return true;
+    default:
+        abort();
+    }
+}
+
 /*
  * Returns the number of contiguous clusters that can be used for an allocating
  * write, but require COW to be performed (this includes yet unallocated space,
@@ -1100,25 +1118,11 @@ static int count_cow_clusters(BlockDriverState *bs, int nb_clusters,
 
     for (i = 0; i < nb_clusters; i++) {
         uint64_t l2_entry = be64_to_cpu(l2_slice[l2_index + i]);
-        QCow2ClusterType cluster_type = qcow2_get_cluster_type(bs, l2_entry);
-
-        switch(cluster_type) {
-        case QCOW2_CLUSTER_NORMAL:
-            if (l2_entry & QCOW_OFLAG_COPIED) {
-                goto out;
-            }
+        if (!cluster_needs_cow(bs, l2_entry)) {
             break;
-        case QCOW2_CLUSTER_UNALLOCATED:
-        case QCOW2_CLUSTER_COMPRESSED:
-        case QCOW2_CLUSTER_ZERO_PLAIN:
-        case QCOW2_CLUSTER_ZERO_ALLOC:
-            break;
-        default:
-            abort();
         }
     }
 
-out:
     assert(i <= nb_clusters);
     return i;
 }
-- 
2.26.2