Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20221004171351.3678194-1-daeho43@gmail.com> <20221004171351.3678194-2-daeho43@gmail.com>
 <Yz6S3kP4rjm5/30N@infradead.org> <Yz8DJROpwCcNyxVX@magnolia>
In-Reply-To: <Yz8DJROpwCcNyxVX@magnolia>
From:   Daeho Jeong <daeho43@gmail.com>
Date:   Mon, 17 Oct 2022 10:03:29 -0700
Message-ID: <CACOAw_z61txMMH+5Pq+4LS5hmC9rbvHaEiY5-V-M9mq56Tx6yg@mail.gmail.com>
Subject: Re: [PATCH v4 2/2] f2fs: introduce F2FS_IOC_START_ATOMIC_REPLACE
To:     "Darrick J. Wong" <djwong@kernel.org>
Cc:     Christoph Hellwig <hch@infradead.org>,
        linux-kernel@vger.kernel.org,
        linux-f2fs-devel@lists.sourceforge.net, kernel-team@android.com,
        Daeho Jeong <daehojeong@google.com>,
        linux-fsdevel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Thu, Oct 6, 2022 at 9:32 AM Darrick J. Wong <djwong@kernel.org> wrote:
>
> On Thu, Oct 06, 2022 at 01:33:34AM -0700, Christoph Hellwig wrote:
> > On Tue, Oct 04, 2022 at 10:13:51AM -0700, Daeho Jeong wrote:
> > > From: Daeho Jeong <daehojeong@google.com>
> > >
> > > introduce a new ioctl to replace the whole content of a file atomically,
> > > which means it induces truncate and content update at the same time.
> > > We can start it with F2FS_IOC_START_ATOMIC_REPLACE and complete it with
> > > F2FS_IOC_COMMIT_ATOMIC_WRITE. Or abort it with
> > > F2FS_IOC_ABORT_ATOMIC_WRITE.
> >
> > It would be great to Cc Darrick and linux-fsdevel as there have been
> > attempts to do this properly at the VFS level instead of a completely
> > undocumented ioctl.
>
> It's been a while since I sent the last RFC, but yes, it's still in my
> queue as part of the xfs online fsck patchserieses.
>
> https://lore.kernel.org/linux-fsdevel/161723932606.3149451.12366114306150243052.stgit@magnolia/
>
> More recent git branch:
> https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux.git/log/?h=atomic-file-updates

Hi,

It's a very interesting suggestion and we might use this in F2FS someday.
However, I think it's not exactly matched for what
F2FS_IOC_START_ATOMIC_REPLACE is doing now.

Thanks for bringing my attention to this.

>
> --D