Re: [PATCH] ovl: Allow changing default fsync_mode

On Tue, Jun 23, 2026 at 9:11 PM Gao Xiang <[email protected]> wrote:
>
>
> (+try to cc more FS people for visibility.)
>
> On 2026/6/23 20:47, Yafang Shao wrote:
> > On Tue, Jun 23, 2026 at 7:59 PM Gao Xiang <[email protected]> wrote:
> >>
> >>
> >>
> >> On 2026/6/23 19:38, Yafang Shao wrote:
> >>> On Tue, Jun 23, 2026 at 6:25 PM Gao Xiang <[email protected]> wrote:
> >>>>
> >>>>
> >>>>
> >>>> On 2026/6/23 18:18, Yafang Shao wrote:
> >>>>> On Tue, Jun 23, 2026 at 6:12 PM Gao Xiang <[email protected]> wrote:
> >>>>>>
> >>>>
> >>>> ...
> >>>>
> >>>>>>
> >>>>>> Again, I don't want such customized messy breaks userspace
> >>>>>> again; with that patch, container runtime needs to consider
> >>>>>> if `volatile` is the default which just breaks the existing
> >>>>>> containerd versions.
> >>>>>
> >>>>> I'll leave this debate to the overlayfs maintainers ;)
> >>>>
> >>>> On my own perspective and be responsible for common users
> >>>> (and as a containerd maintainer [1]),
> >>>
> >>> No wonder containerd is getting harder and harder to use ;)
> >>
> >> What do you mean, can you explain exactly?
> >>
> >> You're just adding a new way to break the existing
> >> applications, no? You just breaks previous shipped
> >> containerd.
> >
> > It's your responsibility to handle the cases where "strict" is
> > explicitly required. Please do your homework. It is not the kernel's
> > fault.
>
> How do you modify the existing applications and scripts
> to adapt your incompatible new Kconfig?

Why do you still insist it's "incompatible"? As far as I can see,
mounting on the same directory is a very rare case, especially in
production environments. If your use case relies on "strict", then
simply don't turn it on. Everything across our large fleet of servers
works perfectly well with it.

>
> >
> >>
> >> Add a way to change the default behavior is fine, but
> >> the new default behavior should be worked with the
> >> same functionality and compatible, but switching to
> >> `volatile` feature is non-compatible and what is why
> >> containerd dropped volatile.
> >
> > It only adds a dynamically changeable config. Why do you insist it
> > breaks everything? Users can always change it whenever they need.
>
> Can you find any Kconfig option that changes user-visible
> default functionality and causes almost any user
> application that relies on remounting to fail to mount
> again? If so, I think we should Cc Linus now.

I can't get you.

-- 
Regards
Yafang