linux-kernel - Re: exfat: Improving exception handling in two functions

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Date:   Wed, 10 Jun 2020 11:27:58 +0200
From:   Markus Elfring <Markus.Elfring@....de>
To:     linux-fsdevel@...r.kernel.org,
        Namjae Jeon <namjae.jeon@...sung.com>,
        Sungjong Seo <sj1557.seo@...sung.com>
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Pali Rohár <pali@...nel.org>,
        Tetsuhiro Kohada <kohada.t2@...il.com>,
        Wei Yongjun <weiyongjun1@...wei.com>
Subject: Re: exfat: Improving exception handling in two functions

Hello,

I have taken another look at pointer usage after calls of the function “brelse”.
My source code analysis approach pointed implementation details
like the following out for further software development considerations.
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/fs/exfat/namei.c?id=3d155ae4358baf4831609c2f9cd09396a2b8badf#n1078

…
		epold = exfat_get_dentry(sb, p_dir, oldentry + 1, &old_bh,
			&sector_old);
		epnew = exfat_get_dentry(sb, p_dir, newentry + 1, &new_bh,
			&sector_new);
		if (!epold || !epnew)
			return -EIO;
…

I suggest to split such an error check.
How do you think about to release a buffer head object for the desired
exception handling if one of these function calls succeeded?

Would you like to adjust such code in the functions “exfat_rename_file”
and “exfat_move_file”?

Regards,
Markus