dcb_write, if write failed, gwbuf wasn't freed. mysql_backend.c gw_MySQLWrite_backend, if dcb wasn'r in POLLING state then write was skpiped but gwbuf wasn't freed. mysql_client.c gw_MySQLWrite_client, disabled the use of dcb_write because it returns different values than the code it replaced. Also removed erroneous call of gwbuf_consume. mysql_common.c mysql_send_custom_error, removed erroneous call of gwbuf_free.