linux-ext4 - Re: [PATCH v3 00/16] Exposing case folding behavior

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Message-ID: <20260113-vorort-pudding-ef90f426d5cf@brauner>
Date: Tue, 13 Jan 2026 10:04:56 +0100
From: Christian Brauner <brauner@...nel.org>
To: Chuck Lever <cel@...nel.org>
Cc: vira@...1.smtp.subspace.kernel.org, Jan Kara <jack@...e.cz>,
	linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org,
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	trondmy@...nel.org, anna@...nel.org, jaegeuk@...nel.org,
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	Chuck Lever <chuck.lever@...cle.com>
Subject: Re: [PATCH v3 00/16] Exposing case folding behavior

On Mon, Jan 12, 2026 at 12:46:13PM -0500, Chuck Lever wrote:
> From: Chuck Lever <chuck.lever@...cle.com>
> 
> Following on from
> 
> https://lore.kernel.org/linux-nfs/20251021-zypressen-bazillus-545a44af57fd@brauner/T/#m0ba197d75b7921d994cf284f3cef3a62abb11aaa
> 
> I'm attempting to implement enough support in the Linux VFS to
> enable file services like NFSD and ksmbd (and user space
> equivalents) to provide the actual status of case folding support
> in local file systems. The default behavior for local file systems
> not explicitly supported in this series is to reflect the usual
> POSIX behaviors:
> 
>   case-insensitive = false
>   case-preserving = true
> 
> The case-insensitivity and case-preserving booleans can be consumed
> immediately by NFSD. These two booleans have been part of the NFSv3
> and NFSv4 protocols for decades, in order to support NFS clients on
> non-POSIX systems.
> 
> Support for user space file servers is why this series exposes case
> folding information via a user-space API. I don't know of any other
> category of user-space application that requires access to case
> folding info.

This all looks good to me.
Just one question: This reads like you are exposing the new file attr
bits via userspace but I can only see changes to the kernel internal
headers not the uapi headers. So are you intentionally not exposing this
as a new uapi extension to file attr or is this an accident?