[PATCH] A basic NFSv4 client for 2.5.x

This patch defines a new switch in fs/Config.in -
  CONFIG_NFS_V4:  enables nfsv4 client

fs/Config.help

@@ -535,6 +535,13 @@ CONFIG_NFS_DIRECTIO
   causes open() to return EINVAL if a file residing in NFS is
   opened with the O_DIRECT flag.
 
+CONFIG_NFS_V4
+  Say Y here if you want your NFS client to be able to speak the newer
+  version 4 of the NFS protocol.  This feature is experimental, and
+  should only be used if you are interested in helping to test NFSv4.
+
+  If unsure, say N.
+
 CONFIG_ROOT_NFS
   If you want your Linux box to mount its whole root file system (the
   one containing the directory /) from some other computer over the

fs/Config.in

@@ -117,6 +117,7 @@ if [ "$CONFIG_NET" = "y" ]; then
    dep_tristate 'InterMezzo file system support (replicating fs) (EXPERIMENTAL)' CONFIG_INTERMEZZO_FS $CONFIG_INET $CONFIG_EXPERIMENTAL
    dep_tristate 'NFS file system support' CONFIG_NFS_FS $CONFIG_INET
    dep_mbool '  Provide NFSv3 client support' CONFIG_NFS_V3 $CONFIG_NFS_FS
+   dep_mbool '  Provide NFSv4 client support (EXPERIMENTAL)' CONFIG_NFS_V4 $CONFIG_NFS_FS $CONFIG_EXPERIMENTAL
    dep_bool '  Root file system on NFS' CONFIG_ROOT_NFS $CONFIG_NFS_FS $CONFIG_IP_PNP
 
    dep_tristate 'NFS server support' CONFIG_NFSD $CONFIG_INET