[DLM] cancel in conversion deadlock [4/6]

When conversion deadlock is detected, cancel the conversion and return
EDEADLK to the application.  This is a new default behavior where before
the dlm would allow the deadlock to exist indefinately.

The DLM_LKF_NODLCKWT flag can now be used in a conversion to prevent the
dlm from performing conversion deadlock detection/cancelation on it.
The DLM_LKF_CONVDEADLK flag can continue to be used as before to tell the
dlm to demote the granted mode of the lock being converted if it gets into
a conversion deadlock.
Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

include/linux/dlm.h

@@ -85,7 +85,11 @@
  * Only relevant to locks originating in userspace.  A persistent lock will not
  * be removed if the process holding the lock exits.
  *
- * DLM_LKF_NODLKWT
+ * DLM_LKF_NODLCKWT
+ *
+ * Do not cancel the lock if it gets into conversion deadlock.
+ * Exclude this lock from being monitored due to DLM_LSFL_TIMEWARN.
+ *
  * DLM_LKF_NODLCKBLK
  *
  * net yet implemented