Re: [PATCH] overlay/029: fix test failure with index feature enabled

[Eryu Guan <guan@eryu.me>]

On Sun, Apr 19, 2020 at 07:12:33PM +0300, Amir Goldstein wrote:
> On Sun, Apr 19, 2020 at 7:05 PM Eryu Guan <guan@eryu.me> wrote:
> >
> > On Thu, Apr 09, 2020 at 02:29:00PM +0300, Amir Goldstein wrote:
> > > When overlayfs index feature is enabled by default in either kernel
> > > config or module parameters, this test fails:
> > >
> > >     mount: /tmp/8751/mnt: mount(2) system call failed: Stale file handle.
> > >     cat: /tmp/8751/mnt/bar: No such file or directory
> > >
> > > The reason is that with index feature enabled, an upper/work dirs cannot
> > > be reused for mounting with a different lower layer.
> >
> > I re-built my test kernel with CONFIG_OVERLAY_FS_INDEX=y, and confirmed
> > /sys/module/overlay/parameters/index is 'Y', but test still passes for
> > me. And I do notice the following info in dmesg:
> >
> > [  598.663923] overlayfs: fs on '/mnt/scratch/ovl-mnt/up' does not support file handles, falling back to index=off,nfs_export=off.
> > [  598.674299] overlayfs: fs on '/mnt/scratch/ovl-mnt/low' does not support file handles, falling back to index=off,nfs_export=off.
> > [  598.684594] overlayfs: fs on '/mnt/scratch/ovl-mnt/' does not support file handles, falling back to index=off,nfs_export=off.
> >
> > Seems it has something to do with nfs_export feature? I have it disabled
> > by default.
> >
> >  # CONFIG_OVERLAY_FS_NFS_EXPORT is not set
> >
> > Could you please help confirm?
> >
> 
> I confirm. enabling index on nested overlay requires that
> the lower overlay has nfs_export enabled.

Thanks!

> 
> Missed that, but in the bug report, CONFIG_OVERLAY_FS_NFS_EXPORT
> was indeed set.

Would you please update the commit log accordingly as well?

> 
> You do not need to rebuild the kernel.
> You can reproduce the failure by setting overlay module parameter before
> running the tests.
> 
> echo Y > /sys/module/overlay/parameters/index
> echo Y > /sys/module/overlay/parameters/nfs_export

Ah, forgot about that.. it's easier now :)

Thanks,
Eryu