re #13613 rb4516 Tunables needs volatile keyword

@@ -18,10 +18,11 @@
  *
  * CDDL HEADER END
  */
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright 2013 Nexenta Systems, Inc.  All rights reserved.
  * Copyright (c) 2015, Joyent, Inc.
  * Copyright (c) 2017 by Delphix. All rights reserved.
  */
 
 /*      Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T     */

@@ -142,11 +143,11 @@
  *
  * the initial value was chosen as being
  * a random string of bits, probably not
  * normally chosen by a systems administrator
  */
-int ncsize = -1;
+volatile int ncsize = -1;
 volatile uint32_t dnlc_nentries = 0;    /* current num of name cache entries */
 static int nc_hashsz;                   /* size of hash table */
 static int nc_hashmask;                 /* size of hash table minus 1 */
 
 /*

@@ -301,13 +302,15 @@
  */
 #define DC_RET_LOW_MEM (dircache_t *)1
 #define VALID_DIR_CACHE(dcp) ((dircache_t *)(dcp) > DC_RET_LOW_MEM)
 
 /* Tunables */
-uint_t dnlc_dir_enable = 1; /* disable caching directories by setting to 0 */
-uint_t dnlc_dir_min_size = 40; /* min no of directory entries before caching */
-uint_t dnlc_dir_max_size = UINT_MAX; /* ditto maximum */
+volatile uint_t dnlc_dir_enable = 1;    /* disable caching directories by */
+                                        /* setting to 0 */
+volatile uint_t dnlc_dir_min_size = 40; /* min no of directory entries before */
+                                        /* caching */
+volatile uint_t dnlc_dir_max_size = UINT_MAX; /* ditto maximum */
 uint_t dnlc_dir_hash_size_shift = 3; /* 8 entries per hash bucket */
 uint_t dnlc_dir_min_reclaim =  350000; /* approx 1MB of dcentrys */
 /*
  * dnlc_dir_hash_resize_shift determines when the hash tables
  * get re-adjusted due to growth or shrinkage