qcow2: flush refcount cache correctly in qcow2_write_snapshots()

Since qcow2 metadata is cached we need to flush the caches, not just the
underlying file.  Use bdrv_flush(bs) instead of bdrv_flush(bs->file).

Also add the error return path when bdrv_flush() fails and move the
flush after checking for qcow2_alloc_clusters() failure so that the
qcow2_alloc_clusters() error return value takes precedence.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c
index eb8fcd55497ff6e5d11b038a01d6abf27b79bd56..f4719d9909c5ae1e35d148d24f73dc510f5b0ce9 100644 (file)
--- a/block/qcow2-snapshot.c
+++ b/block/qcow2-snapshot.c
@@ -180,11 +180,14 @@ static int qcow2_write_snapshots(BlockDriverState *bs)
 
     /* Allocate space for the new snapshot list */
     snapshots_offset = qcow2_alloc_clusters(bs, snapshots_size);
-    bdrv_flush(bs->file);
     offset = snapshots_offset;
     if (offset < 0) {
         return offset;
     }
+    ret = bdrv_flush(bs);
+    if (ret < 0) {
+        return ret;
+    }
 
     /* Write all snapshots to the new list */
     for(i = 0; i < s->nb_snapshots; i++) {