NFSD: Add nfsd4_encode_fattr4_owner_group()

Refactor the encoder for FATTR4_OWNER_GROUP into a helper. In a
subsequent patch, this helper will be called from a bitmask loop.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/nfs4xdr.c

@@ -3201,6 +3201,12 @@ static __be32 nfsd4_encode_fattr4_owner(struct xdr_stream *xdr,
 	return nfsd4_encode_user(xdr, args->rqstp, args->stat.uid);
 }
 
+static __be32 nfsd4_encode_fattr4_owner_group(struct xdr_stream *xdr,
+					      const struct nfsd4_fattr_args *args)
+{
+	return nfsd4_encode_group(xdr, args->rqstp, args->stat.gid);
+}
+
 /*
  * Note: @fhp can be NULL; in this case, we might have to compose the filehandle
  * ourselves.
@@ -3500,8 +3506,8 @@ nfsd4_encode_fattr(struct xdr_stream *xdr, struct svc_fh *fhp,
 			goto out;
 	}
 	if (bmval1 & FATTR4_WORD1_OWNER_GROUP) {
-		status = nfsd4_encode_group(xdr, rqstp, args.stat.gid);
-		if (status)
+		status = nfsd4_encode_fattr4_owner_group(xdr, &args);
+		if (status != nfs_ok)
 			goto out;
 	}
 	if (bmval1 & FATTR4_WORD1_RAWDEV) {