nfsd4: allow setting grace period time

Allow explicit configuration of the grace period time as well as the
lease period time.

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
index b463093..7237776 100644
--- a/fs/nfsd/nfsd.h
+++ b/fs/nfsd/nfsd.h
@@ -228,6 +228,7 @@
 #ifdef CONFIG_NFSD_V4
 
 extern time_t nfsd4_lease;
+extern time_t nfsd4_grace;
 
 /* before processing a COMPOUND operation, we have to check that there
  * is enough space in the buffer for XDR encode to succeed.  otherwise,