nfsd: Add DEALLOCATE support

DEALLOCATE only returns a status value, meaning we can use the noop()
xdr encoder to reply to the client.

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/xdr4.h

@@ -494,6 +494,7 @@ struct nfsd4_op {
 
 		/* NFSv4.2 */
 		struct nfsd4_fallocate		allocate;
+		struct nfsd4_fallocate		deallocate;
 		struct nfsd4_seek		seek;
 	} u;
 	struct nfs4_replay *			replay;