NFSv4: Enable attribute delegations

If we see that the server supports attribute delegations, then request
them by setting the appropriate OPEN arguments.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Lance Shelton <lance.shelton@hammerspace.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

fs/nfs/nfs4proc.c

@@ -1339,8 +1339,13 @@ nfs4_map_atomic_open_share(struct nfs_server *server,
 	if (!(server->caps & NFS_CAP_ATOMIC_OPEN_V1))
 		goto out;
 	/* Want no delegation if we're using O_DIRECT */
-	if (openflags & O_DIRECT)
+	if (openflags & O_DIRECT) {
 		res |= NFS4_SHARE_WANT_NO_DELEG;
+		goto out;
+	}
+	/* res |= NFS4_SHARE_WANT_NO_PREFERENCE; */
+	if (server->caps & NFS_CAP_DELEGTIME)
+		res |= NFS4_SHARE_WANT_DELEG_TIMESTAMPS;
 out:
 	return res;
 }