/***************************************************************************** * * walk through the entire arry and write new parity. This works by * creating two DAGs, one to read a stripe of data and one to write * new parity. The first is executed, the data is xored together, and * then the second is executed. To avoid constantly building and * tearing down the DAGs, we create them a priori and fill them in * with the mapping information as we go along. * * there should never be more than one thread running this. * ****************************************************************************/