Re: [PATCH 2/4] Fix mainline filesystems to handle ATTR_KILL_ bits correctly

[Timothy Shimmin <tes@sgi.com>]

Jeff Layton wrote:
> This should fix all of the filesystems in the mainline kernels to handle
> ATTR_KILL_SUID and ATTR_KILL_SGID correctly. For most of them, this is
> just a matter of making sure that they call generic_attrkill early in
> the setattr inode op.
> 
> Signed-off-by: Jeff Layton <jlayton@redhat.com>
> ---
>  fs/xfs/linux-2.6/xfs_iops.c               |    5 ++++-
> --- a/fs/xfs/linux-2.6/xfs_iops.c
> +++ b/fs/xfs/linux-2.6/xfs_iops.c
> @@ -651,12 +651,15 @@ xfs_vn_setattr(
>  	struct iattr	*attr)
>  {
>  	struct inode	*inode = dentry->d_inode;
> -	unsigned int	ia_valid = attr->ia_valid;
> +	unsigned int	ia_valid;
>  	bhv_vnode_t	*vp = vn_from_inode(inode);
>  	bhv_vattr_t	vattr = { 0 };
>  	int		flags = 0;
>  	int		error;
>  
> +	generic_attrkill(inode->i_mode, attr);
> +	ia_valid = attr->ia_valid;
> +
>  	if (ia_valid & ATTR_UID) {
>  		vattr.va_mask |= XFS_AT_UID;
>  		vattr.va_uid = attr->ia_uid;

Looks reasonable to me for XFS.
Acked-by: Tim Shimmin <tes@sgi.com>

So before, this clearing would happen directly in notify_change()
and now this won't happen until notify_change() calls i_op->setattr
which for a particular fs it can call generic_attrkill() to do it.
So I guess for the cases where i_op->setattr is called outside of
via notify_change, we don't normally have ATTR_KILL_SUID/SGID
set so that nothing will happen there?
I guess just wondering the effect with having the code on all
setattr's. (I'm not familiar with the code path)

--Tim