dlm: add time stamp of blocking callback

Record the time the latest blocking callback was queued for
a lock.  This will be used for debugging in combination with
lock queue timestamp changes in the previous patch.

Signed-off-by: David Teigland <teigland@redhat.com>
diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index dfc57ae..6cfe65b 100644
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -318,6 +318,8 @@
 
 static void queue_bast(struct dlm_rsb *r, struct dlm_lkb *lkb, int rqmode)
 {
+	lkb->lkb_time_bast = ktime_get();
+
 	if (is_master_copy(lkb))
 		send_bast(r, lkb, rqmode);
 	else