Re: [PATCH] xfs: port to vfs{g,u}id_t and associated helpers

Christian Brauner
2022-09-10T09:13:35Z

On Fri, Sep 09, 2022 at 04:40:47PM +0200, Christoph Hellwig wrote:
> On Fri, Sep 09, 2022 at 11:56:59AM +0200, Christian Brauner wrote:
> > A while ago we introduced a dedicated vfs{g,u}id_t type in commit
> > 1e5267cd0895 ("mnt_idmapping: add vfs{g,u}id_t"). We already switched
> > over a good part of the VFS. Ultimately we will remove all legacy
> > idmapped mount helpers that operate only on k{g,u}id_t in favor of the
> > new type safe helpers that operate on vfs{g,u}id_t.
> >
> > Cc: Dave Chinner <dchinner@redhat.com>
> > Cc: Seth Forshee (Digital Ocean) <sforshee@kernel.org>
> > Cc: Christoph Hellwig <hch@lst.de>
> > Cc: Darrick J. Wong <djwong@kernel.org>
> > Cc: linux-xfs@vger.kernel.org
> > Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
> > ---
> > fs/xfs/xfs_inode.c | 5 ++---
> > fs/xfs/xfs_iops.c | 6 ++++--
> > fs/xfs/xfs_itable.c | 8 ++++++--
> > 3 files changed, 12 insertions(+), 7 deletions(-)
> >
> > diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> > index 28493c8e9bb2..bca204a5aecf 100644
> > --- a/fs/xfs/xfs_inode.c
> > +++ b/fs/xfs/xfs_inode.c
> > @@ -835,9 +835,8 @@ xfs_init_new_inode(
> > * ID or one of the supplementary group IDs, the S_ISGID bit is cleared
> > * (and only if the irix_sgid_inherit compatibility variable is set).
> > */
> > - if (irix_sgid_inherit &&
> > - (inode->i_mode & S_ISGID) &&
> > - !in_group_p(i_gid_into_mnt(mnt_userns, inode)))
> > + if (irix_sgid_inherit && (inode->i_mode & S_ISGID) &&
> > + !vfsgid_in_group_p(i_gid_into_vfsgid(mnt_userns, inode)))
> > inode->i_mode &= ~S_ISGID;
> >
> > ip->i_disk_size = 0;
> > diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
> > index 45518b8c613c..5d670c85dcc2 100644
> > --- a/fs/xfs/xfs_iops.c
> > +++ b/fs/xfs/xfs_iops.c
> > @@ -558,6 +558,8 @@ xfs_vn_getattr(
> > struct inode *inode = d_inode(path->dentry);
> > struct xfs_inode *ip = XFS_I(inode);
> > struct xfs_mount *mp = ip->i_mount;
> > + vfsuid_t vfsuid = i_uid_into_vfsuid(mnt_userns, inode);
> > + vfsgid_t vfsgid = i_gid_into_vfsgid(mnt_userns, inode);
> >
> > trace_xfs_getattr(ip);
> >
> > @@ -568,8 +570,8 @@ xfs_vn_getattr(
> > stat->dev = inode->i_sb->s_dev;
> > stat->mode = inode->i_mode;
> > stat->nlink = inode->i_nlink;
> > - stat->uid = i_uid_into_mnt(mnt_userns, inode);
> > - stat->gid = i_gid_into_mnt(mnt_userns, inode);
> > + stat->uid = vfsuid_into_kuid(vfsuid);
> > + stat->gid = vfsgid_into_kgid(vfsgid);
> > stat->ino = ip->i_ino;
> > stat->atime = inode->i_atime;
> > stat->mtime = inode->i_mtime;
> > diff --git a/fs/xfs/xfs_itable.c b/fs/xfs/xfs_itable.c
> > index 36312b00b164..a1c2bcf65d37 100644
> > --- a/fs/xfs/xfs_itable.c
> > +++ b/fs/xfs/xfs_itable.c
> > @@ -66,6 +66,8 @@ xfs_bulkstat_one_int(
> > struct xfs_bulkstat *buf = bc->buf;
> > xfs_extnum_t nextents;
> > int error = -EINVAL;
> > + vfsuid_t vfsuid;
> > + vfsgid_t vfsgid;
> >
> > if (xfs_internal_inum(mp, ino))
> > goto out_advance;
> > @@ -81,14 +83,16 @@ xfs_bulkstat_one_int(
> > ASSERT(ip != NULL);
> > ASSERT(ip->i_imap.im_blkno != 0);
> > inode = VFS_I(ip);
> > + vfsuid = i_uid_into_vfsuid(mnt_userns, inode);
> > + vfsgid = i_gid_into_vfsgid(mnt_userns, inode);
> >
> > /* xfs_iget returns the following without needing
> > * further change.
> > */
> > buf->bs_projectid = ip->i_projid;
> > buf->bs_ino = ino;
> > - buf->bs_uid = from_kuid(sb_userns, i_uid_into_mnt(mnt_userns, inode));
> > - buf->bs_gid = from_kgid(sb_userns, i_gid_into_mnt(mnt_userns, inode));
> > + buf->bs_uid = from_kuid(sb_userns, vfsuid_into_kuid(vfsuid));
> > + buf->bs_gid = from_kgid(sb_userns, vfsgid_into_kgid(vfsgid));
>
> So we convert i_uid into vfsguid into kuid into the user space visible
> one here. I wonder if there is any good short cut, as reading this
> chaing feels odd. But I guess that's what we get for a non-VFS
> ioctl interface exposint uids/gids.

We could add a tiny helper for this for sure but I think there's so
little need for it that it wouldn't make much sense. But if more cases
pop up during conversion of all direct users we should definitely add
one.