BDP_ASYNC
const unsigned int bdp_flags = (nowait ? BDP_ASYNC : 0);
unsigned int bdp_flags = (iter->flags & IOMAP_NOWAIT) ? BDP_ASYNC : 0;
unsigned int bdp_flags = (iocb->ki_flags & IOCB_NOWAIT) ? BDP_ASYNC : 0;
if (flags & BDP_ASYNC) {