Re: [PATCH v4 2/2] f2fs: introduce F2FS_IOC_START_ATOMIC_REPLACE

Re: [PATCH v4 2/2] f2fs: introduce F2FS_IOC_START_ATOMIC_REPLACE

[Christoph Hellwig]

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.

Re: [PATCH v4 2/2] f2fs: introduce F2FS_IOC_START_ATOMIC_REPLACE

[Darrick J. Wong]

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

--D

Re: [PATCH v4 2/2] f2fs: introduce F2FS_IOC_START_ATOMIC_REPLACE

[Daeho Jeong]

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