* IO engine that does regular fallocate to simulate data transfer
* as fio ioengine.
* DDIR_READ does fallocate(,mode = FALLOC_FL_KEEP_SIZE,)
* IO engine that does regular fallocate to simulate data transfer
* as fio ioengine.
* DDIR_READ does fallocate(,mode = FALLOC_FL_KEEP_SIZE,)