@@ -624,6 +624,20 @@ static int refresh_total_sectors(BlockDriverState *bs, int64_t hint)
}
/**
+ * Combines a QDict of new block driver @options with any missing options taken
+ * from @old_options, so that leaving out an option defaults to its old value.
+ */
+static void bdrv_join_options(BlockDriverState *bs, QDict *options,
+ QDict *old_options)
+{
+ if (bs->drv && bs->drv->bdrv_join_options) {
+ bs->drv->bdrv_join_options(options, old_options);
+ } else {
+ qdict_join(options, old_options, false);
+ }
+}
+
+/**
* Set open flags for a given discard mode
*
* Return 0 on success, -1 if the discard mode was invalid.
@@ -1663,7 +1677,7 @@ BlockReopenQueue *bdrv_reopen_queue(BlockReopenQueue *bs_queue,
}
old_options = qdict_clone_shallow(bs->options);
- qdict_join(options, old_options, false);
+ bdrv_join_options(bs, options, old_options);
QDECREF(old_options);
/* bdrv_open() masks this flag out */