linux-kernel - Re: [PATCH v6 9/9] ovl: Support mounting case-insensitive enabled layers

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Message-ID: <CAOQ4uxgMdeiPt1v4s07fZkGbs5+3sJw5VgcFu33_zH1dZtrSsg@mail.gmail.com>
Date: Tue, 26 Aug 2025 09:31:27 +0200
From: Amir Goldstein <amir73il@...il.com>
To: André Almeida <andrealmeid@...lia.com>
Cc: Miklos Szeredi <miklos@...redi.hu>, Theodore Tso <tytso@....edu>, 
	Gabriel Krisman Bertazi <krisman@...nel.org>, linux-unionfs@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org, 
	Alexander Viro <viro@...iv.linux.org.uk>, Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>, 
	kernel-dev@...lia.com
Subject: Re: [PATCH v6 9/9] ovl: Support mounting case-insensitive enabled layers

On Mon, Aug 25, 2025 at 3:31 PM André Almeida <andrealmeid@...lia.com> wrote:
>
> Hi Amir,
>
> Em 22/08/2025 16:17, Amir Goldstein escreveu:
>
> [...]
>
>    /*
> >>>> -        * Allow filesystems that are case-folding capable but deny composing
> >>>> -        * ovl stack from case-folded directories.
> >>>> +        * Exceptionally for layers with casefold, we accept that they have
> >>>> +        * their own hash and compare operations
> >>>>            */
> >>>> -       if (sb_has_encoding(dentry->d_sb))
> >>>> -               return IS_CASEFOLDED(d_inode(dentry));
> >>>> +       if (ofs->casefold)
> >>>> +               return false;
> >>>
> >>> I think this is better as:
> >>>           if (sb_has_encoding(dentry->d_sb))
> >>>                   return false;
> >>>
> >
> > And this still fails the test "Casefold enabled" for me.
> >
> > Maybe you are confused because this does not look like
> > a test failure. It looks like this:
> >
> > generic/999 5s ...  [19:10:21][  150.667994] overlayfs: failed lookup
> > in lower (ovl-lower/casefold, name='subdir', err=-116): parent wrong
> > casefold
> > [  150.669741] overlayfs: failed lookup in lower (ovl-lower/casefold,
> > name='subdir', err=-116): parent wrong casefold
> > [  150.760644] overlayfs: failed lookup in lower (/ovl-lower,
> > name='casefold', err=-66): child wrong casefold
> >   [19:10:24] [not run]
> > generic/999 -- overlayfs does not support casefold enabled layers
> > Ran: generic/999
> > Not run: generic/999
> > Passed all 1 tests
> >
>
> This is how the test output looks before my changes[1] to the test:
>
> $ ./run.sh
> FSTYP         -- ext4
> PLATFORM      -- Linux/x86_64 archlinux 6.17.0-rc1+ #1174 SMP
> PREEMPT_DYNAMIC Mon Aug 25 10:18:09 -03 2025
> MKFS_OPTIONS  -- -F /dev/vdc
> MOUNT_OPTIONS -- -o acl,user_xattr /dev/vdc /tmp/dir2
>
> generic/999 1s ... [not run] overlayfs does not support casefold enabled
> layers
> Ran: generic/999
> Not run: generic/999
> Passed all 1 tests
>
>
> And this is how it looks after my changes[1] to the test:
>
> $ ./run.sh
> FSTYP         -- ext4
> PLATFORM      -- Linux/x86_64 archlinux 6.17.0-rc1+ #1174 SMP
> PREEMPT_DYNAMIC Mon Aug 25 10:18:09 -03 2025
> MKFS_OPTIONS  -- -F /dev/vdc
> MOUNT_OPTIONS -- -o acl,user_xattr /dev/vdc /tmp/dir2
>
> generic/999        1s
> Ran: generic/999
> Passed all 1 tests
>
> So, as far as I can tell, the casefold enabled is not being skipped
> after the fix to the test.

Is this how it looks with your v6 or after fixing the bug:
https://lore.kernel.org/linux-unionfs/68a8c4d7.050a0220.37038e.005c.GAE@google.com/

Because for me this skipping started after fixing this bug
Maybe we fixed the bug incorrectly, but I did not see what the problem
was from a quick look.

Can you test with my branch:
https://github.com/amir73il/linux/commits/ovl_casefold/

>
> [1]
> https://lore.kernel.org/lkml/5da6b0f4-2730-4783-9c57-c46c2d13e848@igalia.com/
>
>
> > I'm not sure I will keep the test this way. This is not very standard nor
> > good practice, to run half of the test and then skip it.
> > I would probably split it into two tests.
> > The first one as it is now will run to completion on kenrels >= v6.17
> > and the Casefold enable test will run on kernels >= v6.18.
> >
> > In any case, please make sure that the test is not skipped when testing
> > Casefold enabled layers
> >
> > And then continue with the missing test cases.
> >
> > When you have a test that passes please send the test itself or
> > a fstest branch for me to test.
>
> Ok!

I assume you are testing with ext4 layers?

If we are both testing the same code and same test and getting different
results I would like to get to the bottom of this, so please share as much
information on your test setup as you can.

Thanks,
Amir.