Re: [PATCH] man/man7/landlock.7: Document whiteout object peculiarities

["Günther Noack" <gnoack3000@gmail.com>]

Hello Alejandro!

On Sun, Oct 11, 2026 at 07:09:31PM +0200, Alejandro Colomar wrote:
> > On Fri, Aug 28, 2026 at 09:44:18PM +0200, Alejandro Colomar wrote:
> > > > Date: 2026-08-28 18:03:41+0200
> > > > From: Günther Noack <gnoack3000@gmail.com>
> > > >
> > > > Bring documentation for LANDLOCK_ACCESS_FS_MAKE_REG in line with the
> > > > Landlock whiteout patch [1].
> > > > 
> > > > Link: [1] <https://lore.kernel.org/all/20260813093157.1436894-3-gnoack@google.com/>
> > > > Link: [2] <https://github.com/landlock-lsm/linux/issues/66>
> > > > ---
> > > >  man/man7/landlock.7 | 3 +++
> > > >  1 file changed, 3 insertions(+)
> > > > 
> > > > diff --git a/man/man7/landlock.7 b/man/man7/landlock.7
> > > > index 880dd50582f3..3642a64ff1f6 100644
> > > > --- a/man/man7/landlock.7
> > > > +++ b/man/man7/landlock.7
> > > > @@ -204,6 +204,9 @@ Create (or rename) a directory.
> > > >  .TP
> > > >  .B LANDLOCK_ACCESS_FS_MAKE_REG
> > > >  Create (or rename or link) a regular file.
> > > > +.IP
> > > > +This also guards the creation of whiteout objects
> > > > +as used in OverlayFS.
> > > 
> > > Reviewed-by: Alejandro Colomar <alx@kernel.org>
> > > 
> > > 
> > > I guess this should not be applied yet, right?  If it's ready, please
> > > let me know.
> > 
> > The whiteout patch has been backported as bugfix to Linux 7.2, 6.18,
> > 6.12, 6.6 and 6.1.  Since it is in stable, I think this can be
> > considered ready for the purpose of putting it into man pages?
> > (Otherwise, we can also wait for the 7.3 release.)
> 
> Yes, it's good for the man pages.  Does it need any update regarding
> version numbers or HISTORY, or should I pick the patch as is?

I think it is fine to pick it as it is.

It was a bugfix and it is available on all Landlock ABI versions
exposed by stable kernels.  So the described behaviour applies on all
supported kernels and Landlock ABI versions.

Because it is a behavioural change, callers can probe for the presence
of the fix with Landlock's "errata" mechanism, as documented in
landlock_create_ruleset(2).  The list of the existing errata is best
checked in the most up-to-date source in the kernel documentation,
which we are also linking from landlock_create_ruleset(2), so that
users are encouraged to look for the most up to date list there.

–Günther