2988 nfssrv: need ability to go to submounts for v3 and v2 protocols
Portions contributed by: Marcel Telka <marcel.telka@nexenta.com>
Portions contributed by: Jean McCormack <jean.mccormack@nexenta.com>
Reviewed by: Yuri Pankov <yuri.pankov@nexenta.com>
Reviewed by: Alek Pinchuk <alek.pinchuk@nexenta.com>
Reviewed by: Dan Fields <dan.fields@nexenta.com>
Reviewed by: Dan McDonald <danmcd@joyent.com>
Change-Id: I6fdf110cc17e789353c4442b83a46cb80643456e

*** 98,107 ****
--- 98,124 ----
                           default values associated with the global tag in
                           /etc/nfs/nfslog.conf are used.  Support of NFS server
                           logging is only available for NFS Version 2 and
                           Version 3 requests.
  
+                nohide    By default, if server exports two filesystems, one of
+                          which is mounted as a child of the other, NFS Version
+                          2 and Version 3 clients must mount both filesystems
+                          explicitly in order to access them.  If a client only
+                          mounts the parent, it will see an empty directory at
+                          the location where the other filesystem is mounted.
+ 
+                          Setting the nohide option on a filesystem causes it
+                          to no longer be hidden in this manner, and the client
+                          will be able to move from the parent filesystem to
+                          this one without noticing the change.  However, some
+                          NFS clients or applications may not function
+                          correctly when this option is used.  In particular,
+                          files on different underlying filesystems may appear
+                          to have the same inode numbers.  The nohide option
+                          only applies to NFS Version 2 and Version 3 requests.
+ 
                 noaclfab  By default, the NFS server will fabricate POSIX-draft
                           style ACLs in response to ACL requests from NFS
                           Version 2 or Version 3 clients accessing shared file
                           systems that do not support POSIX-draft ACLs (such as
                           ZFS).  Specifying noaclfab disables this behavior.
*** 468,473 ****
--- 485,496 ----
       The NFS Version 4 protocol does not use the mountd processing and the
       client's use of /export/foo does not work as it does with NFS Version 2
       and Version 3 and the client receives an error when attempting to mount
       /export/foo.
  
+      The nohide option violates RFC 1094, Network File System Protocol
+      Specification and RFC 1813, NFS: Network File System Version 3 Protocol
+      Specification
+ 
+      The nohide option is provided for compatibility with Linux NFS.
+ 
  illumos                         March 23, 2017                         illumos