+#define R1BIO_Degraded 2
+#define R1BIO_BehindIO 3
+#define R1BIO_Barrier 4
+#define R1BIO_BarrierRetry 5
+/* For write-behind requests, we call bi_end_io when
+ * the last non-write-behind device completes, providing
+ * any write was successful. Otherwise we call when
+ * any write-behind write succeeds, otherwise we call
+ * with failure when last write completes (and all failed).
+ * Record that bi_end_io was called with this flag...
+ */
+#define R1BIO_Returned 6
+