fp_read
error = fp_read(fp, buf, nbyte, &nread, 1, UIO_SYSSPACE);
error = fp_read(iocom->msg_fp, &hdr, sizeof(hdr),
error = fp_read(iocom->msg_fp, &msg->any.head + 1,
error = fp_read(iocom->msg_fp, msg->aux_data,
error = fp_read(jo->fp, &ack, sizeof(ack), &count,
int fp_read(struct file *, void *, size_t, ssize_t *, int, enum uio_seg);