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Date:   Mon, 17 Oct 2022 14:02:55 +0200
From:   David Sterba <dsterba@suse.cz>
To:     Dmitry Vyukov <dvyukov@google.com>
Cc:     dsterba@suse.cz, Hrutvik Kanabar <hrkanabar@gmail.com>,
        Hrutvik Kanabar <hrutvik@google.com>,
        Marco Elver <elver@google.com>,
        Aleksandr Nogikh <nogikh@google.com>,
        kasan-dev@googlegroups.com,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        Theodore Ts'o <tytso@mit.edu>,
        Andreas Dilger <adilger.kernel@dilger.ca>,
        linux-ext4@vger.kernel.org, Chris Mason <clm@fb.com>,
        Josef Bacik <josef@toxicpanda.com>,
        David Sterba <dsterba@suse.com>, linux-btrfs@vger.kernel.org,
        Jaegeuk Kim <jaegeuk@kernel.org>, Chao Yu <chao@kernel.org>,
        linux-f2fs-devel@lists.sourceforge.net,
        "Darrick J . Wong" <djwong@kernel.org>, linux-xfs@vger.kernel.org,
        Namjae Jeon <linkinjeon@kernel.org>,
        Sungjong Seo <sj1557.seo@samsung.com>,
        Anton Altaparmakov <anton@tuxera.com>,
        linux-ntfs-dev@lists.sourceforge.net
Subject: Re: [PATCH RFC 0/7] fs: Debug config option to disable filesystem
 checksum verification for fuzzing
Message-ID: <20221017120255.GM13389@twin.jikos.cz>
Reply-To: dsterba@suse.cz
References: <20221014084837.1787196-1-hrkanabar@gmail.com>
 <20221014091503.GA13389@twin.jikos.cz>
 <CACT4Y+as3SA6C_QFLSeb5JYY30O1oGAh-FVMLCS2NrNahycSoQ@mail.gmail.com>
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On Mon, Oct 17, 2022 at 10:31:03AM +0200, Dmitry Vyukov wrote:
> On Fri, 14 Oct 2022 at 11:15, David Sterba <dsterba@suse.cz> wrote:
> > On Fri, Oct 14, 2022 at 08:48:30AM +0000, Hrutvik Kanabar wrote:
> > > From: Hrutvik Kanabar <hrutvik@google.com>
> > I think the build-time option inflexible, but I see the point when
> > you're testing several filesystems that it's one place to set up the
> > environment. Alternatively I suggest to add sysfs knob available in
> > debuging builds to enable/disable checksum verification per filesystem.
> 
> What usage scenarios do you have in mind for runtime changing of this option?
> I see this option intended only for very narrow use cases which
> require a specially built kernel in a number of other ways (lots of
> which are not tunable at runtime, e.g. debugging configs).

For my own development and testing usecase I'd like to build the kernel
from the same config all the time, then start a VM and run random tests
that do not skip the checksum verification. Then as the last also run
fuzzing with checksums skipped. The debugging (lockdep, various sanity
checks, ...) config options are enabled. We both have a narrow usecase,
what I'm suggesting is a common way to enable them.