1 files changed, 14 insertions, 3 deletions
diff --git a/block.c b/block.c
index db043346d8..97bfb1494f 100644
--- a/block.c
+++ b/block.c
@@ -3426,14 +3426,15 @@ static int bdrv_set_backing_noperm(BlockDriverState *bs,
     return bdrv_set_file_or_backing_noperm(bs, backing_hd, true, tran, errp);
 }
 
-int bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd,
-                        Error **errp)
+int bdrv_set_backing_hd_drained(BlockDriverState *bs,
+                                BlockDriverState *backing_hd,
+                                Error **errp)
 {
     int ret;
     Transaction *tran = tran_new();
 
     GLOBAL_STATE_CODE();
-    bdrv_drained_begin(bs);
+    assert(bs->quiesce_counter > 0);
 
     ret = bdrv_set_backing_noperm(bs, backing_hd, tran, errp);
     if (ret < 0) {
@@ -3443,7 +3444,17 @@ int bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd,
     ret = bdrv_refresh_perms(bs, tran, errp);
 out:
     tran_finalize(tran, ret);
+    return ret;
+}
 
+int bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd,
+                        Error **errp)
+{
+    int ret;
+    GLOBAL_STATE_CODE();
+
+    bdrv_drained_begin(bs);
+    ret = bdrv_set_backing_hd_drained(bs, backing_hd, errp);
     bdrv_drained_end(bs);
 
     return ret;