5508 move segvn #defines into seg_vn.c
Reviewed by: Marcel Telka <marcel@telka.sk>

*** 18,27 ****
--- 18,28 ----
   *
   * CDDL HEADER END
   */
  /*
   * Copyright (c) 1986, 2010, Oracle and/or its affiliates. All rights reserved.
+  * Copyright 2015 Nexenta Systems, Inc.  All rights reserved.
   */
  
  /*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
  /*        All Rights Reserved   */
  
*** 71,80 ****
--- 72,102 ----
  #include <sys/proc.h>
  #include <sys/task.h>
  #include <sys/project.h>
  #include <sys/zone.h>
  #include <sys/shm_impl.h>
+ 
+ /*
+  * segvn_fault needs a temporary page list array.  To avoid calling kmem all
+  * the time, it creates a small (PVN_GETPAGE_NUM entry) array and uses it if
+  * it can.  In the rare case when this page list is not large enough, it
+  * goes and gets a large enough array from kmem.
+  *
+  * This small page list array covers either 8 pages or 64kB worth of pages -
+  * whichever is smaller.
+  */
+ #define PVN_MAX_GETPAGE_SZ      0x10000
+ #define PVN_MAX_GETPAGE_NUM     0x8
+ 
+ #if PVN_MAX_GETPAGE_SZ > PVN_MAX_GETPAGE_NUM * PAGESIZE
+ #define PVN_GETPAGE_SZ  ptob(PVN_MAX_GETPAGE_NUM)
+ #define PVN_GETPAGE_NUM PVN_MAX_GETPAGE_NUM
+ #else
+ #define PVN_GETPAGE_SZ  PVN_MAX_GETPAGE_SZ
+ #define PVN_GETPAGE_NUM btop(PVN_MAX_GETPAGE_SZ)
+ #endif
+ 
  /*
   * Private seg op routines.
   */
  static int      segvn_dup(struct seg *seg, struct seg *newseg);
  static int      segvn_unmap(struct seg *seg, caddr_t addr, size_t len);