Draw9p.readdrawrefresh = function(dd, offset, callback){
	cons.log("readdrawrefresh");

	var conn = this.conns[dd.drawdir];
	if(conn == undefined){
		return callback.error("invalid draw connection");
	}

	/* XXX This breaks if multiple reads are outstanding on the */
	/* refresh file!  Should we permit this and use some sort of */
	/* array of refreshcallbacks, or should we be setting (and */
	/* obeying!) the exclusive-use bit on the relevant [qf]id? */
	if(conn.refreshcallback != undefined){

		return callback.error("multiple reads are not allowed");
	}

	conn.refreshcallback = callback;
}