bdrv_co_common_block_status_above not only returns whether the block is
allocated, but also if it contains zeroes.

Signed-off-by: Vincent Vanlaer <libvirt-e6954efa@volkihar.be>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
---
 block/commit.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/block/commit.c b/block/commit.c
index 7c3fdcb0ca..8dee25b313 100644
--- a/block/commit.c
+++ b/block/commit.c
@@ -15,6 +15,8 @@
 #include "qemu/osdep.h"
 #include "qemu/cutils.h"
 #include "trace.h"
+#include "block/block-common.h"
+#include "block/coroutines.h"
 #include "block/block_int.h"
 #include "block/blockjob_int.h"
 #include "qapi/error.h"
@@ -167,9 +169,13 @@ static int coroutine_fn commit_run(Job *job, Error **errp)
             break;
         }
         /* Copy if allocated above the base */
-        ret = blk_co_is_allocated_above(s->top, s->base_overlay, true,
-                                        offset, COMMIT_BUFFER_SIZE, &n);
-        copy = (ret > 0);
+        WITH_GRAPH_RDLOCK_GUARD() {
+            ret = bdrv_co_common_block_status_above(blk_bs(s->top),
+                s->base_overlay, true, true, offset, COMMIT_BUFFER_SIZE,
+                &n, NULL, NULL, NULL);
+        }
+
+        copy = (ret >= 0 && ret & BDRV_BLOCK_ALLOCATED);
         trace_commit_one_iteration(s, offset, n, ret);
         if (copy) {
             assert(n < SIZE_MAX);
-- 
2.44.1