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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Tue, 27 Apr 2021 13:05:13 -0700
Message-ID: <CAHk-=wjrpinf=8gAjxyPoXT0jbK6-U3Urawiykh-zpxeo47Vhg@mail.gmail.com>
Subject: Re: [GIT PULL] iomap: new code for 5.13-rc1
To:     Christoph Hellwig <hch@lst.de>
Cc:     "Darrick J. Wong" <djwong@kernel.org>, Jia He <justin.he@arm.com>,
        Al Viro <viro@zeniv.linux.org.uk>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        linux-xfs <linux-xfs@vger.kernel.org>,
        Dave Chinner <david@fromorbit.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Eric Sandeen <sandeen@sandeen.net>
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On Tue, Apr 27, 2021 at 12:57 PM Christoph Hellwig <hch@lst.de> wrote:
>
> I'm aware of %pD, but 4 components here are not enough.  People
> need to distinguish between xfstests runs and something real in
> the system for these somewhat scary sounding messages.

So how many _would_ be enough? IOW, what would make %pD work better
for this case?

Why are the xfstest messages so magically different from real cases
that they'd need to be separately distinguished, and that can't be
done with just the final path component?

If you think the message is somehow unique and the path is something
secure and identifiable, you're very confused. file_path() is in no
way more "secure" than using %pD4 would be, since if there's some
actual bad actor they can put newlines etc in the pathname, they can
do chroot() etc to make the path look anything they like.

So I seriously don't understand the thinking where you claim that "<n>
components are not enough". Please explain why that could ever be a
real issue.

             Linus