BH_Dirty, /* Is dirty */
BH_Lock, /* Is locked */
BH_Req, /* Has been submitted for I/O */
+ BH_Uptodate_Lock,/* Used by the first bh in a page, to serialise
+ * IO completion of other buffers in the page
+ */
BH_Mapped, /* Has a disk mapping */
BH_New, /* Disk mapping was newly created by get_block */