switch /dev/kmsg to ->write_iter()

	char buf[8192];

};

static ssize_t devkmsg_writev(struct kiocb *iocb, const struct iovec *iv,

			      unsigned long count, loff_t pos)

static ssize_t devkmsg_write(struct kiocb *iocb, struct iov_iter *from)

{

	char *buf, *line;

	int i;

	int level = default_message_loglevel;

	int facility = 1;	/* LOG_USER */

	size_t len = iov_length(iv, count);

	size_t len = iocb->ki_nbytes;

	ssize_t ret = len;

	if (len > LOG_LINE_MAX)

	if (buf == NULL)

		return -ENOMEM;

	line = buf;

	for (i = 0; i < count; i++) {

		if (copy_from_user(line, iv[i].iov_base, iv[i].iov_len)) {

			ret = -EFAULT;

			goto out;

		}

		line += iv[i].iov_len;

	buf[len] = '\0';

	if (copy_from_iter(buf, len, from) != len) {

		kfree(buf);

		return -EFAULT;

	}

	/*

			line = endp;

		}

	}

	line[len] = '\0';

	printk_emit(facility, level, NULL, 0, "%s", line);

out:

	kfree(buf);

	return ret;

}

const struct file_operations kmsg_fops = {

	.open = devkmsg_open,

	.read = devkmsg_read,

	.aio_write = devkmsg_writev,

	.write_iter = devkmsg_write,

	.llseek = devkmsg_llseek,

	.poll = devkmsg_poll,

	.release = devkmsg_release,