Re: [PATCH 2/3] xfs: allow setting xattrs on special files

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

On Tue, Jul 29, 2025 at 01:00:36PM +0200, Andrey Albershteyn wrote:
> From: Andrey Albershteyn <aalbersh@redhat.com>
> 
> XFS does't have extended attributes manipulation ioctls for special
> files. Changing or reading file extended attributes is rejected for them

"extended file attributes" or "fileattrs" as Amir suggested,
but never "extended attributes" because that's a separate thing.

(no need to drop the rvb over this)

--D

> in xfs_fileattr_*et().
> 
> In XFS, this is necessary to work for project quota directories.
> When project is set up, xfs_quota opens and calls FS_IOC_SETFSXATTR on
> every inode in the directory. However, special files are skipped due to
> open() returning a special inode for them. So, they don't even get to
> this check.
> 
> The recently added file_getattr/file_setattr will call xfs_fileattr_*et,
> on special files. This patch allows reading/changing extended file
> attributes on special files.
> 
> Signed-off-by: Andrey Albershteyn <aalbersh@redhat.com>
> Reviewed-by: Darrick J. Wong <djwong@kernel.org>
> ---
>  fs/xfs/xfs_ioctl.c | 6 ------
>  1 file changed, 6 deletions(-)
> 
> diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> index fe1f74a3b6a3..f3c89172cc27 100644
> --- a/fs/xfs/xfs_ioctl.c
> +++ b/fs/xfs/xfs_ioctl.c
> @@ -512,9 +512,6 @@ xfs_fileattr_get(
>  {
>  	struct xfs_inode	*ip = XFS_I(d_inode(dentry));
>  
> -	if (d_is_special(dentry))
> -		return -ENOTTY;
> -
>  	xfs_ilock(ip, XFS_ILOCK_SHARED);
>  	xfs_fill_fsxattr(ip, XFS_DATA_FORK, fa);
>  	xfs_iunlock(ip, XFS_ILOCK_SHARED);
> @@ -736,9 +733,6 @@ xfs_fileattr_set(
>  
>  	trace_xfs_ioctl_setattr(ip);
>  
> -	if (d_is_special(dentry))
> -		return -ENOTTY;
> -
>  	if (!fa->fsx_valid) {
>  		if (fa->flags & ~(FS_IMMUTABLE_FL | FS_APPEND_FL |
>  				  FS_NOATIME_FL | FS_NODUMP_FL |
> 
> -- 
> 2.49.0
> 
>