copy_mblks
err = copy_mblks(buf, inlen, UIO_WRITE, mp);
err = copy_mblks(buf, outlen, UIO_READ, mp);
err = copy_mblks(buf, inlen, UIO_WRITE, mp);
err = copy_mblks(buf, outlen, UIO_READ, mp);
static int copy_mblks(void *buf, size_t buflen, enum uio_rw, mblk_t *m);