Re: [PATCH v11 08/15] xfs: Report case sensitivity in fileattr_get

["Darrick J. Wong" <djwong@kernel.org>]

On Fri, Apr 24, 2026 at 09:53:10PM -0400, Chuck Lever wrote:
> From: Chuck Lever <chuck.lever@oracle.com>
> 
> Upper layers such as NFSD need to query whether a filesystem
> is case-sensitive. Add FS_XFLAG_CASEFOLD to xfs_ip2xflags()
> when the filesystem is formatted with the ASCIICI feature
> flag. This serves both FS_IOC_FSGETXATTR (via xfs_fill_fsxattr() in
> xfs_fileattr_get()) and XFS_IOC_BULKSTAT (which populates bs_xflags
> directly from xfs_ip2xflags()), so bulkstat consumers and per-inode
> queries see a consistent view of the filesystem's case-folding
> behavior.
> 
> XFS always preserves case. XFS is case-sensitive by default, but
> supports ASCII case-insensitive lookups when formatted with the
> ASCIICI feature flag.
> 
> Reviewed-by: Roland Mainz <roland.mainz@nrubsig.org>
> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> ---
>  fs/xfs/libxfs/xfs_inode_util.c | 2 ++
>  fs/xfs/xfs_ioctl.c             | 7 +++++++
>  2 files changed, 9 insertions(+)
> 
> diff --git a/fs/xfs/libxfs/xfs_inode_util.c b/fs/xfs/libxfs/xfs_inode_util.c
> index 551fa51befb6..82be54b6f8d3 100644
> --- a/fs/xfs/libxfs/xfs_inode_util.c
> +++ b/fs/xfs/libxfs/xfs_inode_util.c
> @@ -130,6 +130,8 @@ xfs_ip2xflags(
>  
>  	if (xfs_inode_has_attr_fork(ip))
>  		flags |= FS_XFLAG_HASATTR;
> +	if (xfs_has_asciici(ip->i_mount))
> +		flags |= FS_XFLAG_CASEFOLD;
>  	return flags;
>  }
>  
> diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> index ed9b4846c05f..5a58fb0bad2b 100644
> --- a/fs/xfs/xfs_ioctl.c
> +++ b/fs/xfs/xfs_ioctl.c
> @@ -472,6 +472,13 @@ xfs_fill_fsxattr(
>  
>  	fileattr_fill_xflags(fa, xfs_ip2xflags(ip));
>  
> +	/*
> +	 * FS_XFLAG_CASEFOLD is read-only; hide it from the legacy
> +	 * flags view so chattr's RMW cycle does not pass it back to
> +	 * xfs_fileattr_set().
> +	 */
> +	fa->flags &= ~FS_CASEFOLD_FL;

I don't understand this at all.  Yes, FS_XFLAG_CASEFOLD is readonly, but
how does clearing FS_CASEFOLD_FL from the fileattr_get output (without
clearing XFLAG_CASEFOLD!) solve anything?  This makes the reported
output inconsistent between fsgetxattr and getflags -- one reports case
folding, the other reports no casefolding.

If you want to avoid fileattr_set returning EINVAL when setting
attributes due to the casefold flag, then don't you want to check the
flag state vs. xfs_has_asciici() in the *fileattr_set* path?

--D

> +
>  	if (ip->i_diflags & XFS_DIFLAG_EXTSIZE) {
>  		fa->fsx_extsize = XFS_FSB_TO_B(mp, ip->i_extsize);
>  	} else if (ip->i_diflags & XFS_DIFLAG_EXTSZINHERIT) {
> 
> -- 
> 2.53.0
> 
>