<Linux> Linux Driver文件读取

void driver_read_file(const char *filename)
{
	struct file *pfile;
	mm_segment_t old_fs;
	char read_buf[100] = {0};
	struct inode *inode;
	int ret;
	off_t fsize;
	int pkg_size = 64;
	int left;
	int read_size;

	pfile = filp_open(filename, O_RDONLY, 0);

	if (IS_ERR(pfile)) {
		pr_err("Open %s failed!\n", filename);
		return;
	}
	old_fs = get_fs();
	set_fs(KERNEL_DS);

	inode = pfile->f_dentry->d_inode;
	fsize = inode->i_size;

	pr_err("file size: %ld bytes\n", fsize);
	pr_err("file content: \n");
	left = fsize;
	while (left > 0) {
		if (left > pkg_size) {
			read_size = pkg_size;
		}
		else {
			read_size = left;
		}
		ret = pfile->f_op->read(pfile, read_buf, read_size, &pfile->f_pos);
		if (ret < 0) {
			pr_err("read data failed, ret: %d\n", ret);

			filp_close(pfile, NULL);
			set_fs(old_fs);
			return;
		}
		pr_err("%s\n", read_buf);
		left -= read_size;
	}
	filp_close(pfile, NULL);
	set_fs(old_fs);
}