On Thu, 2022-11-17 at 22:12 +0100, Richard Weinberger wrote: > ----- Ursprüngliche Mail ----- > > Von: "Jeff Layton" <jlayton@xxxxxxxxxx> > > What happens when CROSSMOUNT isn't enabled and someone tries to stroll > > into an automount point? I'm guessing the automount happens but the > > export is denied? > > Exactly. > > On the other hand, why should knfsd not trigger automounts? > Almost any userspace interaction would also do so. > I have no issue with knfsd activity triggering an automount, but I think it'd be best if we don't do that when knfsd can't do anything with the resulting filesystem. Automounts can be expensive. > > It seems like LOOKUP_AUTOMOUNT ought to be conditional > > on the parent export having CROSSMOUNT set. > > > > There's also another caller of follow_down too, the UNIX98 pty code. > > This may be harmless for it, but it'd be best not to perturb that if we > > can help it. > > > > Maybe follow_down can grow a lookupflags argument? > > So, in nfsd_cross_mnt() the follow_down() helper should use LOOKUP_AUTOMOUNT only > if exp->ex_flags & NFSEXP_CROSSMOUNT is true? > Sounds sane, thanks for the pointer. > Yeah, I think so. I do wonder if we ought to make any provision for "nohide" exports, but since you have to enumerate those explicitly, it shouldn't be a huge problem for someone to just ensure that they're mounted beforehand. -- Jeff Layton <jlayton@xxxxxxxxxx>
