On Sat, 2012-11-24 at 14:35 -0800, Eric W. Biederman wrote: > Miklos Szeredi <mik...@szeredi.hu> writes: > > > On Sat, Nov 24, 2012 at 1:07 PM, Eric W. Biederman > > <ebied...@xmission.com> wrote: > >> Ian Kent <ra...@themaw.net> writes: > >> > >>> On Sat, 2012-11-24 at 10:23 +0800, Ian Kent wrote: > >>>> On Fri, 2012-11-23 at 15:30 +0100, Miklos Szeredi wrote: > > > >>>> AFAICS autofs mounts mounted with MS_PRIVATE in the initial namespace do > >>>> propagate to the clone when it's created so I'm assuming subsequent > >>>> mounts would also. If these mounts are busy in some way they can't be > >>>> umounted in the clone unless "/" is marked private before attempting the > >>>> umount. > > Subsequent mounts after the clone do not have a mechanism to propogate > with MS_PRIVATE. As creating a new mount namespaces is essentially > an instance of mount --bind. Those semantics are a little unintuitive > I have to admit. > > >>> This may sound stupid but if there something like, say, MS_NOPROPAGATE > >>> then the problem I see would pretty much just go away. No more need to > >>> umount existing mounts and container instances would be isolated. But, I > >>> guess, I'm not considering the possibility of cloned of processes as > >>> well .... if that makes sense, ;) > >> > >> Something is very weird is going on. MS_PRIVATE should be the > >> MS_NOPROPOGATE you are looking for. There is also MS_UNBINDABLE. > >> which is a stronger form of MS_PRIVATE and probably worth play with. > >> > > > > MS_UNBINDABLE says: skip this mount when copying a mount tree, such > > as when the mount namespace is cloned. > > > > If you set MS_UNBINDABLE on autofs mounts then they will simply not > > appear in a cloned namespace. Which sounds like a good idea, no? > > Good point. If the desire is for a mount to be managed by autofs > setting MS_UNBINDABLE seems required.
Arrgh, I know that's something I should have looked into long ago. The fact is that autofs mounts are directly related to a specific path defined by automount maps that are associated with the daemon so bind mounting them elsewhere makes no sense. Is it necessary (or sensible) to use MS_PRIVATE with MS_UNBINDABLE? > > Eric > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
