+/*
+ * Metadata updates are handled by the monitor thread,
+ * as it has exclusive access to the metadata.
+ * When the manager want to updates metadata, either
+ * for it's own reason (e.g. committing a spare) or
+ * on behalf of mdadm, it creates a metadata_update
+ * structure and queues it to the monitor.
+ * Updates are created and processed by code under the
+ * superswitch. All common code sees them as opaque
+ * blobs.
+ */
+extern struct metadata_update *update_queue, *update_queue_handled;