FOP_BUFFER_WASYNC
.fop_flags = FOP_BUFFER_RASYNC | FOP_BUFFER_WASYNC,
(file->f_op->fop_flags & FOP_BUFFER_WASYNC)))
FOP_BUFFER_WASYNC | FOP_DIO_PARALLEL_WRITE |
!(req->file->f_op->fop_flags & FOP_BUFFER_WASYNC) &&