On Thu, May 09, 2024 at 05:14:59PM +0200, Andrey Albershteyn wrote:
> As XFS didn't have ioctls for special files setting an inode
> extended attributes was rejected for them in xfs_fileattr_set().
> Same applies for reading.
>
> With XFS's project quota directories this is necessary. When project
> is setup, 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 further patch introduces XFS_IOC_SETFSXATTRAT which will call
> xfs_fileattr_set/get() on a special file. This patch add handling of
> setting xflags and project ID for special files.
>
> Signed-off-by: Andrey Albershteyn <aalbersh@xxxxxxxxxx>
> ---
> fs/xfs/xfs_ioctl.c | 96 ++++++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 92 insertions(+), 4 deletions(-)
>
> diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> index f0117188f302..515c9b4b862d 100644
> --- a/fs/xfs/xfs_ioctl.c
> +++ b/fs/xfs/xfs_ioctl.c
> @@ -459,9 +459,6 @@ 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);
> @@ -721,6 +718,97 @@ xfs_ioctl_setattr_check_projid(
> return 0;
> }
>
> +static int
> +xfs_fileattr_spec_set(
> + struct mnt_idmap *idmap,
> + struct dentry *dentry,
> + struct fileattr *fa)
> +{
> + struct xfs_inode *ip = XFS_I(d_inode(dentry));
> + struct xfs_mount *mp = ip->i_mount;
> + struct xfs_trans *tp;
> + struct xfs_dquot *pdqp = NULL;
> + struct xfs_dquot *olddquot = NULL;
> + int error;
> +
> + if (!fa->fsx_valid)
> + return -EOPNOTSUPP;
> +
> + if (fa->fsx_extsize ||
> + fa->fsx_nextents ||
> + fa->fsx_cowextsize)
> + return -EOPNOTSUPP;
> +
> + error = xfs_ioctl_setattr_check_projid(ip, fa);
> + if (error)
> + return error;
> +
> + /*
> + * If disk quotas is on, we make sure that the dquots do exist on disk,
> + * before we start any other transactions. Trying to do this later
> + * is messy. We don't care to take a readlock to look at the ids
> + * in inode here, because we can't hold it across the trans_reserve.
> + * If the IDs do change before we take the ilock, we're covered
> + * because the i_*dquot fields will get updated anyway.
> + */
> + if (fa->fsx_valid && XFS_IS_QUOTA_ON(mp)) {
Didn't we already check fsx_valid?
Also, what's different about the behavior of setxattr on special files
(vs. directories and regular files) such that we need a separate function?
Is it to disable the ability to set the extent size hints or the xflags?
--D
> + error = xfs_qm_vop_dqalloc(ip, VFS_I(ip)->i_uid,
> + VFS_I(ip)->i_gid, fa->fsx_projid,
> + XFS_QMOPT_PQUOTA, NULL, NULL, &pdqp);
> + if (error)
> + return error;
> + }
> +
> + tp = xfs_ioctl_setattr_get_trans(ip, pdqp);
> + if (IS_ERR(tp)) {
> + error = PTR_ERR(tp);
> + goto error_free_dquots;
> + }
> +
> + error = xfs_ioctl_setattr_xflags(tp, ip, fa);
> + if (error)
> + goto error_trans_cancel;
> +
> + /*
> + * Change file ownership. Must be the owner or privileged. CAP_FSETID
> + * overrides the following restrictions:
> + *
> + * The set-user-ID and set-group-ID bits of a file will be cleared upon
> + * successful return from chown()
> + */
> +
> + if ((VFS_I(ip)->i_mode & (S_ISUID | S_ISGID)) &&
> + !capable_wrt_inode_uidgid(idmap, VFS_I(ip), CAP_FSETID))
> + VFS_I(ip)->i_mode &= ~(S_ISUID | S_ISGID);
> +
> + /* Change the ownerships and register project quota modifications */
> + if (ip->i_projid != fa->fsx_projid) {
> + if (XFS_IS_PQUOTA_ON(mp)) {
> + olddquot =
> + xfs_qm_vop_chown(tp, ip, &ip->i_pdquot, pdqp);
> + }
> + ip->i_projid = fa->fsx_projid;
> + }
> +
> + error = xfs_trans_commit(tp);
> +
> + /*
> + * Release any dquot(s) the inode had kept before chown.
> + */
> + xfs_qm_dqrele(olddquot);
> + xfs_qm_dqrele(pdqp);
> +
> + return error;
> +
> +error_trans_cancel:
> + xfs_trans_cancel(tp);
> +error_free_dquots:
> + xfs_qm_dqrele(pdqp);
> + return error;
> +
> + return 0;
> +}
> +
> int
> xfs_fileattr_set(
> struct mnt_idmap *idmap,
> @@ -737,7 +825,7 @@ xfs_fileattr_set(
> trace_xfs_ioctl_setattr(ip);
>
> if (d_is_special(dentry))
> - return -ENOTTY;
> + return xfs_fileattr_spec_set(idmap, dentry, fa);
>
> if (!fa->fsx_valid) {
> if (fa->flags & ~(FS_IMMUTABLE_FL | FS_APPEND_FL |
> --
> 2.42.0
>
>
