re #13613 rb4516 Tunables needs volatile keyword

@@ -21,10 +21,11 @@
 /*
  * Copyright 2007 Sun Microsystems, Inc.
  * All rights reserved.  Use is subject to license terms.
  */
 /*
+ * Copyright 2013 Nexenta Systems, Inc.  All rights reserved.
  * Copyright 2015 Joyent, Inc.
  */
 
 #ifndef _SYS_FS_TMP_H
 #define _SYS_FS_TMP_H

@@ -77,11 +78,11 @@
  * NB: If tmpfs allocates too much swap space, other processes will be
  * unable to execute.
  */
 #define TMPMINFREE      2 * 1024 * 1024 /* 2 Megabytes */
 
-extern size_t   tmpfs_minfree;          /* Anonymous memory in pages */
+extern volatile size_t  tmpfs_minfree;  /* Anonymous memory in pages */
 
 /*
  * tmpfs can allocate only a certain percentage of kernel memory,
  * which is used for tmpnodes, directories, file names, etc.
  * This is statically set as TMPMAXFRACKMEM of physical memory.

@@ -88,11 +89,11 @@
  * The actual number of allocatable bytes can be patched in tmpfs_maxkmem.
  */
 #define TMPMAXFRACKMEM  25      /* 1/25 of physical memory */
 
 extern size_t   tmp_kmemspace;
-extern size_t   tmpfs_maxkmem;  /* Allocatable kernel memory in bytes */
+extern volatile size_t  tmpfs_maxkmem;  /* Allocatable kernel memory in bytes */
 
 extern  void    tmpnode_init(struct tmount *, struct tmpnode *,
         struct vattr *, struct cred *);
 extern  int     tmpnode_trunc(struct tmount *, struct tmpnode *, ulong_t);
 extern  void    tmpnode_growmap(struct tmpnode *, ulong_t);