block: remove bs from lists before closing

Close involves flush that can be performed asynchronously and bs
must be protected from being referenced before it is deleted.

Signed-off-by: Anton Kuchin <antonkuchin@yandex-team.ru>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block.c

@@ -4082,14 +4082,14 @@ static void bdrv_delete(BlockDriverState *bs)
     assert(bdrv_op_blocker_is_empty(bs));
     assert(!bs->refcnt);
 
-    bdrv_close(bs);
-
     /* remove from list, if necessary */
     if (bs->node_name[0] != '\0') {
         QTAILQ_REMOVE(&graph_bdrv_states, bs, node_list);
     }
     QTAILQ_REMOVE(&all_bdrv_states, bs, bs_list);
 
+    bdrv_close(bs);
+
     g_free(bs);
 }