Re: [PATCH v7 07/16] ext4: Report case sensitivity in fileattr_get

["Chuck Lever" <cel@kernel.org>]

On Thu, Jan 22, 2026, at 7:29 PM, Darrick J. Wong wrote:
> On Thu, Jan 22, 2026 at 11:03:02AM -0500, Chuck Lever wrote:
>> From: Chuck Lever <chuck.lever@oracle.com>
>> 
>> Report ext4's case sensitivity behavior via the FS_XFLAG_CASEFOLD
>> flag. ext4 always preserves case at rest.
>> 
>> Case sensitivity is a per-directory setting in ext4. If the queried
>> inode is a casefolded directory, report case-insensitive; otherwise
>> report case-sensitive (standard POSIX behavior).
>> 
>> Reviewed-by: Jan Kara <jack@suse.cz>
>> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
>> ---
>>  fs/ext4/ioctl.c | 7 +++++++
>>  1 file changed, 7 insertions(+)
>> 
>> diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
>> index 7ce0fc40aec2..462da7aadc80 100644
>> --- a/fs/ext4/ioctl.c
>> +++ b/fs/ext4/ioctl.c
>> @@ -996,6 +996,13 @@ int ext4_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
>>  	if (ext4_has_feature_project(inode->i_sb))
>>  		fa->fsx_projid = from_kprojid(&init_user_ns, ei->i_projid);
>>  
>> +	/*
>> +	 * Case folding is a directory attribute in ext4. Set FS_XFLAG_CASEFOLD
>> +	 * for directories with the casefold attribute; all other inodes use
>> +	 * standard case-sensitive semantics.
>> +	 */
>> +	if (IS_CASEFOLDED(inode))
>> +		fa->fsx_xflags |= FS_XFLAG_CASEFOLD;
>
> Curious.  Shouldn't the VFS set FS_XFLAG_CASEFOLD if the VFS casefolding
> flag is set?
>
> OTOH, there are more filesystems that apparently support casefolding
> (given the size of this patchset) than actually set S_CASEFOLD.  I think
> I'm ignorant of something here...

I'm not clear if there's a review action needed. Help?


-- 
Chuck Lever