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

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Message-ID: <774aac29-837d-4692-b744-e168d969a221@kernel.org>
Date: Tue, 13 Jan 2026 08:58:45 -0500
From: Chuck Lever <cel@...nel.org>
To: Christian Brauner <brauner@...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 1/13/26 4:04 AM, Christian Brauner wrote:
> 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?

The intention is to expose the new bits to user space. IIRC those got
removed from uapi headers when I converted from using statx. I can fix
that up and post a v4.


-- 
Chuck Lever