+/*
+ * Write life time hint values.
+ */
+enum rw_hint {
+	WRITE_LIFE_NONE = 0,
+	WRITE_LIFE_SHORT,
+	WRITE_LIFE_MEDIUM,
+	WRITE_LIFE_LONG,
+	WRITE_LIFE_EXTREME,
+};
+
+#define RW_HINT_MASK		0x7	/* 3 bits */

FYI, exposing enums in a uapi is always a bit problematic, due to
different ABI rules.  It might be better to make these explicit defines
at least for the uapi.

Btw, I think it might make sense to merge this with patch 5.