drbd: Implemented the disk-timeout option

When the disk-timeout is active, and it expires for a single request,
we consider the local disk as D_FAILED. Note: With this change,
I made both timeout based state transitions HARD state transitions.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
diff --git a/include/linux/drbd_nl.h b/include/linux/drbd_nl.h
index 7203c9e..a8706f0 100644
--- a/include/linux/drbd_nl.h
+++ b/include/linux/drbd_nl.h
@@ -31,6 +31,7 @@
 	NL_INTEGER(	56,	T_MAY_IGNORE,	max_bio_bvecs)
 	NL_BIT(		57,	T_MAY_IGNORE,	no_disk_barrier)
 	NL_BIT(		58,	T_MAY_IGNORE,	no_disk_drain)
+	NL_INTEGER(	89,	T_MAY_IGNORE,	disk_timeout)
 )
 
 NL_PACKET(detach, 4,