Re: [PATCH 1/3] xfs: fix quota accounting when a mount is idmapped

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

On Wed, Mar 03, 2021 at 02:44:01PM +0000, Christian Brauner wrote:
> On Tue, Mar 02, 2021 at 02:28:22PM -0800, Darrick J. Wong wrote:
> > From: Darrick J. Wong <djwong@kernel.org>
> > 
> > Nowadays, we indirectly use the idmap-aware helper functions in the VFS
> > to set the initial uid and gid of a file being created.  Unfortunately,
> > we didn't convert the quota code, which means we attach the wrong dquots
> > to files created on an idmapped mount.
> > 
> > Fixes: f736d93d76d3 ("xfs: support idmapped mounts")
> > Signed-off-by: Darrick J. Wong <djwong@kernel.org>
> > ---
> 
> This looks good but it misses one change, I think. The
> xfs_ioctl_setattr() needs to take the mapping into account as well:
> 
> diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> index 99dfe89a8d08..067366bf9a59 100644
> --- a/fs/xfs/xfs_ioctl.c
> +++ b/fs/xfs/xfs_ioctl.c
> @@ -1460,8 +1460,8 @@ xfs_ioctl_setattr(
>          * because the i_*dquot fields will get updated anyway.
>          */
>         if (XFS_IS_QUOTA_ON(mp)) {
> -               error = xfs_qm_vop_dqalloc(ip, VFS_I(ip)->i_uid,
> -                               VFS_I(ip)->i_gid, fa->fsx_projid,
> +               error = xfs_qm_vop_dqalloc(ip, i_uid_into_mnt(mnt_userns, VFS_I(ip)),
> +                               i_gid_into_mnt(mnt_userns, VFS_I(ip)), fa->fsx_projid,
>                                 XFS_QMOPT_PQUOTA, NULL, NULL, &pdqp);

The uid/gid parameters here don't matter because the "XFS_QMOPT_PQUOTA"
flag by itself here means that _dqalloc only looks at the project id
argument.

>                 if (error)
>                         return error;
> 
> This should cover all callsites.
> 
> Acked-by: Christian Brauner <christian.brauner@ubuntu.com>

Thanks!

--D

> >  fs/xfs/xfs_inode.c   |   14 ++++++++------
> >  fs/xfs/xfs_symlink.c |    3 ++-
> >  2 files changed, 10 insertions(+), 7 deletions(-)
> > 
> > 
> > diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> > index 46a861d55e48..f93370bd7b1e 100644
> > --- a/fs/xfs/xfs_inode.c
> > +++ b/fs/xfs/xfs_inode.c
> > @@ -1007,9 +1007,10 @@ xfs_create(
> >  	/*
> >  	 * Make sure that we have allocated dquot(s) on disk.
> >  	 */
> > -	error = xfs_qm_vop_dqalloc(dp, current_fsuid(), current_fsgid(), prid,
> > -					XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT,
> > -					&udqp, &gdqp, &pdqp);
> > +	error = xfs_qm_vop_dqalloc(dp, fsuid_into_mnt(mnt_userns),
> > +			fsgid_into_mnt(mnt_userns), prid,
> > +			XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT,
> > +			&udqp, &gdqp, &pdqp);
> >  	if (error)
> >  		return error;
> >  
> > @@ -1157,9 +1158,10 @@ xfs_create_tmpfile(
> >  	/*
> >  	 * Make sure that we have allocated dquot(s) on disk.
> >  	 */
> > -	error = xfs_qm_vop_dqalloc(dp, current_fsuid(), current_fsgid(), prid,
> > -				XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT,
> > -				&udqp, &gdqp, &pdqp);
> > +	error = xfs_qm_vop_dqalloc(dp, fsuid_into_mnt(mnt_userns),
> > +			fsgid_into_mnt(mnt_userns), prid,
> > +			XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT,
> > +			&udqp, &gdqp, &pdqp);
> >  	if (error)
> >  		return error;
> >  
> > diff --git a/fs/xfs/xfs_symlink.c b/fs/xfs/xfs_symlink.c
> > index 1379013d74b8..7f368b10ded1 100644
> > --- a/fs/xfs/xfs_symlink.c
> > +++ b/fs/xfs/xfs_symlink.c
> > @@ -182,7 +182,8 @@ xfs_symlink(
> >  	/*
> >  	 * Make sure that we have allocated dquot(s) on disk.
> >  	 */
> > -	error = xfs_qm_vop_dqalloc(dp, current_fsuid(), current_fsgid(), prid,
> > +	error = xfs_qm_vop_dqalloc(dp, fsuid_into_mnt(mnt_userns),
> > +			fsgid_into_mnt(mnt_userns), prid,
> >  			XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT,
> >  			&udqp, &gdqp, &pdqp);
> >  	if (error)
> >