From: Alberto Garcia <berto@igalia.com>

Signed-off-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/mirror.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/block/mirror.c b/block/mirror.c
index 726d3c27fb..010fdafd79 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -630,6 +630,10 @@ static int mirror_exit_common(Job *job)
     }
     s->prepared = true;
 
+    if (bdrv_chain_contains(src, target_bs)) {
+        bdrv_unfreeze_backing_chain(mirror_top_bs, target_bs);
+    }
+
     bdrv_release_dirty_bitmap(src, s->dirty_bitmap);
 
     /* Make sure that the source BDS doesn't go away during bdrv_replace_node,
@@ -1639,6 +1643,10 @@ static void mirror_start_job(const char *job_id, BlockDriverState *bs,
                 goto fail;
             }
         }
+
+        if (bdrv_freeze_backing_chain(mirror_top_bs, target, errp) < 0) {
+            goto fail;
+        }
     }
 
     QTAILQ_INIT(&s->ops_in_flight);
-- 
2.20.1