Re: [PATCH 2/4] xfs: allow renames of project-less inodes

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

On Thu, May 09, 2024 at 05:14:58PM +0200, Andrey Albershteyn wrote:
> Identical problem as worked around in commit e23d7e82b707 ("xfs:
> allow cross-linking special files without project quota") exists
> with renames. Renaming special file without project ID is not
> possible inside PROJINHERIT directory.
> 
> Special files inodes can not have project ID set from userspace and
> are skipped during initial project setup. Those inodes are left
> project-less in the project directory. New inodes created after
> project initialization do have an ID. Creating hard links or
> renaming those project-less inodes then fails on different ID check.
> 
> Add workaround to allow renames of special files without project ID.
> 
> Signed-off-by: Andrey Albershteyn <aalbersh@redhat.com>
> ---
>  fs/xfs/xfs_inode.c | 15 +++++++++++++--
>  1 file changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> index 58fb7a5062e1..508113515eec 100644
> --- a/fs/xfs/xfs_inode.c
> +++ b/fs/xfs/xfs_inode.c
> @@ -3275,8 +3275,19 @@ xfs_rename(
>  	 */
>  	if (unlikely((target_dp->i_diflags & XFS_DIFLAG_PROJINHERIT) &&
>  		     target_dp->i_projid != src_ip->i_projid)) {
> -		error = -EXDEV;
> -		goto out_trans_cancel;
> +		/*
> +		 * Project quota setup skips special files which can
> +		 * leave inodes in a PROJINHERIT directory without a
> +		 * project ID set. We need to allow renames to be made
> +		 * to these "project-less" inodes because userspace
> +		 * expects them to succeed after project ID setup,
> +		 * but everything else should be rejected.
> +		 */
> +		if (!special_file(VFS_I(src_ip)->i_mode) ||
> +		    src_ip->i_projid != 0) {
> +			error = -EXDEV;
> +			goto out_trans_cancel;
> +		}
>  	}

Should this be a shared helper called by xfs_rename and xfs_link?

--D

>  
>  	/* RENAME_EXCHANGE is unique from here on. */
> -- 
> 2.42.0
> 
>