+/* these are flags for extent_clear_unlock_delalloc */
+#define EXTENT_CLEAR_UNLOCK_PAGE 0x1
+#define EXTENT_CLEAR_UNLOCK 0x2
+#define EXTENT_CLEAR_DELALLOC 0x4
+#define EXTENT_CLEAR_DIRTY 0x8
+#define EXTENT_SET_WRITEBACK 0x10
+#define EXTENT_END_WRITEBACK 0x20
+#define EXTENT_SET_PRIVATE2 0x40
+#define EXTENT_CLEAR_ACCOUNTING 0x80
+