nfsd: support callbacks with gss flavors

This patch adds server-side support for callbacks other than AUTH_SYS.

Signed-off-by: Olga Kornievskaia <aglo@citi.umich.edu>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

net/sunrpc/rpc_pipe.c

@@ -407,6 +407,7 @@ enum {
 	RPCAUTH_nfs,
 	RPCAUTH_portmap,
 	RPCAUTH_statd,
+	RPCAUTH_nfsd4_cb,
 	RPCAUTH_RootEOF
 };
 
@@ -440,6 +441,10 @@ static struct rpc_filelist files[] = {
 		.name = "statd",
 		.mode = S_IFDIR | S_IRUGO | S_IXUGO,
 	},
+	[RPCAUTH_nfsd4_cb] = {
+		.name = "nfsd4_cb",
+		.mode = S_IFDIR | S_IRUGO | S_IXUGO,
+	},
 };
 
 enum {