On Mon, 2012-11-26 at 07:25 +0800, Ian Kent wrote: > On Sat, 2012-11-24 at 14:35 -0800, Eric W. Biederman wrote: > > Miklos Szeredi <miklos@xxxxxxxxxx> writes: > > > > > On Sat, Nov 24, 2012 at 1:07 PM, Eric W. Biederman > > > <ebiederm@xxxxxxxxxxxx> wrote: > > >> Ian Kent <raven@xxxxxxxxxx> 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. Except, AFAICS, they do appear in the clone. > > Is it necessary (or sensible) to use MS_PRIVATE with MS_UNBINDABLE? and specifying MS_PRIVATE as well gives an EINVAL return. > > > > > Eric > > > > > -- > To unsubscribe from this list: send the line "unsubscribe autofs" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
