[PATCH 1/2] vfs: Allow filesystems with foreign owner IDs to override UID checks

[Christian Brauner]

On Tue, Oct 21, 2025 at 02:20:21PM +0100, David Howells wrote:
> Christian Brauner <brauner at kernel.org> wrote:
> 
> > > +	if (unlikely(inode->i_op->have_same_owner)) {
> > 
> > Same, as above: similar to IOP_FASTPERM this should use a flag to avoid pointer derefs.
> 
> Can we do these IOP_* flags better?  Surely we can determine at the point the
> inode has its ->i_op assigned that these things are provided?  This optimises
> the case where they don't exist at the expense of the case where they do (we
> still have to check the pointer every time).
> 
> > > +	if (unlikely(inode->i_op->have_same_owner)) {

I think I mentioned this off-list. It looks like we can but I don't know
if there was any history behind not doing it that way. But please try.