linux-ext4 - Re: [PATCH v7 01/16] fs: Add case sensitivity flags to file

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Message-Id: <bb2bb55c-6078-4494-9851-c684dfd9aa8c@app.fastmail.com>
Date: Thu, 22 Jan 2026 19:42:15 -0500
From: "Chuck Lever" <cel@...nel.org>
To: "Darrick J. Wong" <djwong@...nel.org>
Cc: "Alexander Viro" <viro@...iv.linux.org.uk>,
 "Christian Brauner" <brauner@...nel.org>, "Jan Kara" <jack@...e.cz>,
 linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org,
 linux-xfs@...r.kernel.org, linux-cifs@...r.kernel.org,
 linux-nfs@...r.kernel.org, linux-api@...r.kernel.org,
 linux-f2fs-devel@...ts.sourceforge.net,
 "OGAWA Hirofumi" <hirofumi@...l.parknet.co.jp>,
 "Namjae Jeon" <linkinjeon@...nel.org>,
 "Sungjong Seo" <sj1557.seo@...sung.com>,
 "Yuezhang Mo" <yuezhang.mo@...y.com>,
 almaz.alexandrovich@...agon-software.com,
 "Viacheslav Dubeyko" <slava@...eyko.com>, glaubitz@...sik.fu-berlin.de,
 frank.li@...o.com, "Theodore Tso" <tytso@....edu>,
 adilger.kernel@...ger.ca, "Carlos Maiolino" <cem@...nel.org>,
 "Steve French" <sfrench@...ba.org>, "Paulo Alcantara" <pc@...guebit.org>,
 "Ronnie Sahlberg" <ronniesahlberg@...il.com>,
 "Shyam Prasad N" <sprasad@...rosoft.com>,
 "Trond Myklebust" <trondmy@...nel.org>,
 "Anna Schumaker" <anna@...nel.org>, "Jaegeuk Kim" <jaegeuk@...nel.org>,
 "Chao Yu" <chao@...nel.org>, "Hans de Goede" <hansg@...nel.org>,
 senozhatsky@...omium.org, "Chuck Lever" <chuck.lever@...cle.com>
Subject: Re: [PATCH v7 01/16] fs: Add case sensitivity flags to file_kattr

On Thu, Jan 22, 2026, at 7:26 PM, Darrick J. Wong wrote:
> On Thu, Jan 22, 2026 at 11:02:56AM -0500, Chuck Lever wrote:
>> From: Chuck Lever <chuck.lever@...cle.com>
>> 
>> Enable upper layers such as NFSD to retrieve case sensitivity
>> information from file systems by adding FS_XFLAG_CASEFOLD and
>> FS_XFLAG_CASENONPRESERVING flags.
>> 
>> Filesystems report case-insensitive or case-nonpreserving behavior
>> by setting these flags directly in fa->fsx_xflags. The default
>> (flags unset) indicates POSIX semantics: case-sensitive and
>> case-preserving. These flags are read-only; userspace cannot set
>> them via ioctl.
>> 
>> Remove struct file_kattr initialization from fileattr_fill_xflags()
>> and fileattr_fill_flags(). Callers at ioctl/syscall entry points
>> zero-initialize the struct themselves, which allows them to pass
>> hints (flags_valid, fsx_valid) to the filesystem's ->fileattr_get()
>> callback via the fa argument. Filesystem handlers that invoke these
>> fill functions can now set flags directly in fa->fsx_xflags before
>> calling them, without the fill functions zeroing those values.
>
> In hindsight I regret not asking for the file_kattr initialization
> change to be in a separate patch.

If I’m asked to post another revision of this series, I’ll look at splitting
1/16 into two patches.

>> Case sensitivity information is exported to userspace via the
>> fa_xflags field in the FS_IOC_FSGETXATTR ioctl and file_getattr()
>> system call.
>> 
>> Signed-off-by: Chuck Lever <chuck.lever@...cle.com>
>
> The UAPI changes still look ok to me.  AFAICT the file_kattr
> initialization now seem like they don't zap fields to confuse
> vfs_fileattr_get.
>
> Reviewed-by: "Darrick J. Wong" <djwong@...nel.org>

-- 
Chuck Lever