On Wed, 2015-02-18 at 20:31 -0500, J. Bruce Fields wrote: > On Thu, Feb 19, 2015 at 08:39:01AM +0800, Ian Kent wrote: > > On Wed, 2015-02-18 at 15:59 -0500, J. Bruce Fields wrote: > > > On Wed, Feb 18, 2015 at 12:31:32PM -0500, J. Bruce Fields wrote: > > > > On Wed, Feb 18, 2015 at 12:06:20PM -0500, J. Bruce Fields wrote: > > > > > On Fri, Feb 06, 2015 at 09:47:25AM +0800, Ian Kent wrote: > > > > > > On Thu, 2015-02-05 at 15:14 +0000, David Howells wrote: > > > > > > > > > > > > > > > + /* If running within a container use the container > > > > > > > > namespace */ > > > > > > > > + if (current->nsproxy->net_ns != &init_net) > > > > > > > > > > > > > > Is that a viable check? Is it possible to have a container that > > > > > > > shares > > > > > > > networking details? > > > > > > > > > > > > That's up for discussion. > > > > > > > > > > > > I thought about it and concluded that the check is probably not > > > > > > sufficient for any of the cases. > > > > > > > > > > > > I left it like that because I'm not sure exactly what the use cases > > > > > > are, > > > > > > hoping it promote discussion and here we are. > > > > > > > > > > > > I also think the current container environments don't share net > > > > > > namespace with the root init net namspace, necessarily, because thy > > > > > > are > > > > > > containers, ;) > > > > > > > > > > > > TBH I haven't looked at the user space container creation code but I > > > > > > expect it could be done that way if it was needed, so the answer is > > > > > > yes > > > > > > and no, ;) > > > > > > > > > > > > The questions then are do we need to check anything else, and what > > > > > > environment should the callback use in the different cases, and what > > > > > > other cases might break if we change it? > > > > > > > > > > > > For example, should the fs namespace also be checked for all of > > > > > > these > > > > > > cases, since we're executing a callback, or is whatever that's set > > > > > > to in > > > > > > the container always what's required for locating the executable. > > > > > > > > > > What would be the disadvantage of setting UMH_USE_NS unconditionally > > > > > here? > > > > > > > > In the nfs idmapping case, the mapping is per-nfs_client. > > > > > > > > Can nfs_idmap_new be the one that calls umh_get_init_task, with the > > > > corresponding put done in nfs_idmap_delete, or is there some reason that > > > > doesn't work? > > > > > > It's confusing sorting out possible use cases, but I think both of these > > > are reasonable: > > > > > > - mount an nfs filesystem from the host, then spawn containers > > > that all use that filesystem. > > > - mount an nfs filesystem from within a container. > > > > > > Your approach might work for the second, but in the first case we'll end > > > up with idmappers from multiple containers all trying to do the > > > idmapping for the shared filesystem. > > > > These patches are examples for context. > > > > Working out whether to run in a namespace or not was always going to be > > difficult, specifically for the case you point out. Maybe we can make > > use of some other information, namespace information in the super block > > perhaps, or something else, or perhaps we will need to add some > > information for this, not sure yet. We'll need to work together on that. > > > > TBH, I'm not that focused on the use cases because the base > > implementation is still undergoing significant change although I believe > > the use of a flag to request namespace execution is a good approach. > > That probably won't change. > > The flag requests that we use the container of the currently executing > task. In neither the nfs idmapper nor the nfsd state-recovery case is > that the correct choice.
OK, I'll drop those patches then. Ian -- 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/
