[PATCH v5 bpf-next 1/5] namei: Introduce new helper function path_walk_parent()

[Jan Kara]

On Tue 24-06-25 10:37:36, Song Liu wrote:
> On Tue, Jun 24, 2025 at 5:18 AM Jan Kara <jack at suse.cz> wrote:
> > > + *
> > > + * Returns: either an ERR_PTR() or the chosen parent which will have had
> > > + * the refcount incremented.
> > > + */
> >
> > The behavior with LOOKUP_NO_XDEV is kind of odd (not your fault) and
> > interestingly I wasn't able to find a place that would depend on the path
> > being updated in that case. So either I'm missing some subtle detail (quite
> > possible) or we can clean that up in the future.
> 
> We have RESOLVE_NO_XDEV in uapi/linux/openat2.h, so I guess we
> cannot really remove it?

I didn't mean to remove the LOOKUP_NO_XDEV flag, I meant to not update the
passed path if LOOKUP_NO_XDEV is set, we are crossing the mountpoint and
thus returning -EXDEV. As far as I've checked once we return error,
everybody just path_put()s the nd->path so its update is just pointless.
But there are many (indirect) callers so I might have missed some case.

								Honza
-- 
Jan Kara <jack at suse.com>
SUSE Labs, CR