block: Block all intermediate nodes in commit_active_start()

When block-commit is launched without the top parameter, it uses
internally a mirror block job. In that case all intermediate nodes
between the active and base nodes must be blocked as well.
Signed-off-by: NAlberto Garcia <berto@igalia.com>
Reviewed-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

block/mirror.c

@@ -997,6 +997,14 @@ static void mirror_start_job(const char *job_id, BlockDriverState *bs,
     }
 
     block_job_add_bdrv(&s->common, target);
+    /* In commit_active_start() all intermediate nodes disappear, so
+     * any jobs in them must be blocked */
+    if (bdrv_chain_contains(bs, target)) {
+        BlockDriverState *iter;
+        for (iter = backing_bs(bs); iter != target; iter = backing_bs(iter)) {
+            block_job_add_bdrv(&s->common, iter);
+        }
+    }
 
     s->common.co = qemu_coroutine_create(mirror_run, s);
     trace_mirror_start(bs, s, s->common.co, opaque);