NFSD: Use simple_read_from_buffer for coping data to userspace

{

	static u64 val;

	char read_buf[25];

	size_t size, ret;

	size_t size;

	loff_t pos = *ppos;

	if (!pos)

		nfsd_inject_get(file_inode(file)->i_private, &val);

	size = scnprintf(read_buf, sizeof(read_buf), "%llu\n", val);

	if (pos < 0)

		return -EINVAL;

	if (pos >= size || !len)

		return 0;

	if (len > size - pos)

		len = size - pos;

	ret = copy_to_user(buf, read_buf + pos, len);

	if (ret == len)

		return -EFAULT;

	len -= ret;

	*ppos = pos + len;

	return len;

	return simple_read_from_buffer(buf, len, ppos, read_buf, size);

}

static ssize_t fault_inject_write(struct file *file, const char __user *buf,