re #13613 rb4516 Tunables needs volatile keyword

@@ -20,10 +20,13 @@
  */
 /*
  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
  */
+/*
+ * Copyright 2013 Nexenta Systems, Inc.  All rights reserved.
+ */
 
 #include <sys/systm.h>
 #include <sys/types.h>
 #include <sys/vnode.h>
 #include <sys/errno.h>

@@ -37,12 +40,12 @@
 #include <sys/fs/ufs_inode.h>
 #include <sys/fs/ufs_filio.h>
 #include <sys/fs/ufs_log.h>
 #include <sys/fs/ufs_bio.h>
 #include <sys/atomic.h>
+#include <sys/sunddi.h>
 
-extern int              maxphys;
 extern uint_t           bypass_snapshot_throttle_key;
 
 extern struct kmem_cache        *lufs_sv;
 extern struct kmem_cache        *lufs_bp;