Re: [LTP] [PATCH] syscalls/fanotify26: Add directory cases for the nested event

[Petr Vorel <pvorel@suse.cz>]

> On Tue, Nov 3, 2026 at 8:24 AM Petr Vorel <pvorel@suse.cz> wrote:

> > Hi Amir, Edvard,

> > > On Sat, Oct 31, 2026 at 10:13 PM Edvard Conrad <edvard@tuta.io> wrote:

> > > > A directory on overlayfs reaches its real directory through
> > > > ovl_dir_open_realfile() rather than backing_file_open(), so the fix
> > > > for regular files, commit c3d355f427ce ("fs: let backing files
> > > > inherit FMODE_NONOTIFY from the user file"), does not cover it: a
> > > > listener that marks the backing filesystem with FAN_OPEN_PERM |
> > > > FAN_ONDIR is still sent a nested permission event from its own
> > > > read(2) when the reported path is an overlay directory.

> > > > Add the directory counterparts of the two existing cases. The
> > > > listener's expected event mask stays FAN_OPEN_PERM: FAN_ONDIR is not
> > > > reported to a group without FAN_REPORT_FID.

> > > > The fourth case fails on a kernel without the pending fix "ovl:
> > > > inherit FMODE_NONOTIFY when opening directory realfiles".

> > > > Signed-off-by: Edvard Conrad <edvard@tuta.io>

> > > Reviewed-by: Amir Goldstein <amir73il@gmail.com>

> > > > ---
> > > > Depends on the pending overlayfs fix, posted by Amir on the kernel
> > > > thread:
> > > >   https://lore.kernel.org/all/CAOQ4uxjm=cGPnug18VuhKqiMvkWwLPNLO_TE3KxO8iLZG+veYQ@mail.gmail.com/
> > > > Without it the fourth case fails on current mainline, so this should
> > > > wait in the queue until that fix is in Linus' tree; a linux-git tag for
> > > > it can then be added. The first three cases pass on v7.4-rc1 material
> > > > today.

> > > > Tested in a VM, each kernel run once and with -i 2:

> > > >   kernel                              file+backing  dir+backing
> > > >   v6.13                               PASS          FAIL
> > > >   6b4b543fa18 (no fix)                FAIL          FAIL
> > > >   + c3d355f427ce (files, in Linus')   PASS          FAIL
> > > >   + the pending ovl fix               PASS          PASS

> > > > The "overlay mark only" cases pass everywhere. The directory case
> > > > fails on v6.13 too: overlayfs never passed the nonotify state on to
> > > > the real directory, so it predates the 6.14 change that broke files.

> > > As far as I can tell its a regression from
> > > 130fdbc3d1f99 ("ovl: pass correct flags for opening real directory")

> > > Thanks for adding this test.
> > > I added your Tested-by to the fix patch.

> > I'm going to merge today. So there will be hash for fixing kernel commit,
> > thanks for info.


> FYI, Edvard found another bug and has written an extra test case to cover it
> the expected kernel fix is going to cover the directory test cases in this patch
> as well as the extra test case:

> https://lore.kernel.org/linux-unionfs/P5Qu3co--N-9@tuta.io/

Thanks a lot for info!

> Up to you if you want to merge now or wait for the extra test case.

I merged that one, I suppose there will be more patches (more testcases,
git hash of the fix).

Kind regards,
Petr

> Thanks,
> Amir.

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