NEX-15279 support NFS server in zone
NEX-15520 online NFS shares cause zoneadm halt to hang in nfs_export_zone_fini
Portions contributed by: Dan Kruchinin dan.kruchinin@nexenta.com
Portions contributed by: Stepan Zastupov stepan.zastupov@gmail.com
Reviewed by: Joyce McIntosh <joyce.mcintosh@nexenta.com>
Reviewed by: Rob Gittins <rob.gittins@nexenta.com>
Reviewed by: Gordon Ross <gordon.ross@nexenta.com>

*** 16,29 ****
   * fields enclosed by brackets "[]" replaced with your own identifying
   * information: Portions Copyright [yyyy] [name of copyright owner]
   *
   * CDDL HEADER END
   */
  /*
   * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
   * Copyright 2015 Joyent, Inc. All rights reserved.
!  * Copyright 2014 Nexenta Systems, Inc. All rights reserved.
   * Copyright 2014 Igor Kozhukhov <ikozhukhov@gmail.com>.
   */
  
  #ifndef _SYS_ZONE_H
  #define _SYS_ZONE_H
--- 16,33 ----
   * fields enclosed by brackets "[]" replaced with your own identifying
   * information: Portions Copyright [yyyy] [name of copyright owner]
   *
   * CDDL HEADER END
   */
+ 
  /*
   * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
+  */
+ 
+ /*
   * Copyright 2015 Joyent, Inc. All rights reserved.
!  * Copyright 2018 Nexenta Systems, Inc.
   * Copyright 2014 Igor Kozhukhov <ikozhukhov@gmail.com>.
   */
  
  #ifndef _SYS_ZONE_H
  #define _SYS_ZONE_H
*** 635,645 ****
  /*
   * Special value of zone_psetid to indicate that pools are disabled.
   */
  #define ZONE_PS_INVAL   PS_MYID
  
- 
  extern zone_t zone0;
  extern zone_t *global_zone;
  extern uint_t maxzones;
  extern rctl_hndl_t rc_zone_nlwps;
  extern rctl_hndl_t rc_zone_nprocs;
--- 639,648 ----
*** 777,786 ****
--- 780,794 ----
   * Special processes visible in all zones.
   */
  #define ZONE_SPECIALPID(x)       ((x) == 0 || (x) == 1)
  
  /*
+  * A root vnode of the current zone.
+  */
+ #define ZONE_ROOTVP()   (curproc->p_zone->zone_rootvp)
+ 
+ /*
   * Zone-safe version of thread_create() to be used when the caller wants to
   * create a kernel thread to run within the current zone's context.
   */
  extern kthread_t *zthread_create(caddr_t, size_t, void (*)(), void *, size_t,
      pri_t);