"H. Peter Anvin" <h...@zytor.com> writes: > On April 11, 2016 5:10:47 PM PDT, ebied...@xmission.com wrote: >>Linus Torvalds <torva...@linux-foundation.org> writes: >> >>> On Mon, Apr 11, 2016 at 4:37 PM, Eric W. Biederman >>> <ebied...@xmission.com> wrote: >>>> >>>> My practical concern if we worked through the implementation details >>>> would be how would it interact with people who bind mount >>/dev/pts/ptmx >>>> on top of /dev/ptmx. We might get some strange new errors. >>> >>> Yes, please don't let's play "clever" games. The semantics should be >>> fairly straightforward. >> >>Actually for me this is about keeping the semantics simpler, and coming >>up with a higher performance implementation. >> >>A dentry that does an automount is already well defined. >> >>Making the rule that accessing /dev/ptmx causes an automount of >>/dev/pts/ptmx on top of the device node at /dev/ptmx is really simple, >>with no special games. It also makes it more obvious to userspace what >>is going on. AKA allows userspace to know which superblock does an >>open >>ptmx master tty belongs to (and it happens in a backwards and forwards >>compatible way). >> >>My only concern is with this very minor change in semantics will >>anything care. I need to implement and test to find out. >> >>I think I see an implementation that Al won't grumble too loudly about. >> >>Anyway I am going to try this and see what I can see. >> >>Eric > > Why bother with an automount? You can look up ../ptmx from the devpts > get_super method and just do the bind mount once. No fuss, no muss. > What's wrong with that?
Perhaps I am reading the code wrong but as I read it that information is simply not available in get_super. Eric
