re #13613 rb4516 Tunables needs volatile keyword

@@ -18,10 +18,11 @@
  *
  * CDDL HEADER END
  */
 /*
  * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright 2013 Nexenta Systems, Inc.  All rights reserved.
  */
 
 /* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
 /*      All Rights Reserved   */
 

@@ -1580,11 +1581,11 @@
 extern void     nfs4_destroy_dot_entries(void);
 extern struct nfs4_callback_globals     *nfs4_get_callback_globals(void);
 
 extern struct nfs4_server nfs4_server_lst;
 
-extern clock_t nfs_write_error_interval;
+extern volatile clock_t nfs_write_error_interval;
 
 #endif /* _KERNEL */
 
 /*
  * Flags for nfs4getfh_otw.