Re: [PATCH 4/4] ovl: Expose the filesystem encoding through sysfs

["Pali Rohár" <pali@kernel.org>]

On Tuesday 29 September 2026 16:15:04 Amir Goldstein wrote:
> On Mon, Sep 28, 2026 at 11:32 PM Gabriel Krisman Bertazi
> <krisman@suse.de> wrote:
> >
> > This patch reproduces the same interface from ext4/f2fs to have feature
> > parity, so users don't need to rely on parsing dmesg or trying +F on a
> > temporary directory just to check for support.  Note there is no
> > encoding_flags file, as none are supported by ovl.
> >
> 
> Gabriel,
> 
> I am not ok with this API.
> It is wrong in several ways.
> It is not generic, we have already file_getattr() to get casefold status.
> There was a suggestion by Pali [1] to get the supported xflags - statx style,
> which can be a way to say if a fs could return FS_XFLAG_CASEFOLD.

Yea, sorry for that. I have not finished it, I did not have time. But I
would like to address this as this is something was was asked more times...

> In Chuck's v2 [2] FILEATTR_CASEFOLD_TYPE was already suggested
> as an extension to file_getattr(). I think we can still do that if we include
> proper versioning in the casefold type.
> 
> TBH, I don't think anyone requested this - you only mentioned
> the need to know if tmpfs was mounted with casefold on and that
> doesn't mean that etx4/ovl patches are justified, but ext4 can decide
> for themselves.
> 
> The point is that this sysfs is not going to be the standard for all the
> fs that can return the FS_XFLAG_CASEFOLD, so I see no reason
> to add this sysfs interface to ovl.
> 
> Thanks,
> Amir.
> 
> [1] https://lore.kernel.org/linux-fsdevel/20250216164029.20673-4-pali@kernel.org/
> [2] https://lore.kernel.org/linux-fsdevel/20251211152116.480799-2-cel@kernel.org/