On Thu, Jun 27, 2013 at 08:02:05AM -0500, Serge Hallyn wrote: > Quoting Dave Chinner (david@xxxxxxxxxxxxx): > > On Wed, Jun 26, 2013 at 05:30:17PM -0400, Dwight Engen wrote: > > > On Wed, 26 Jun 2013 12:09:24 +1000 > > > Dave Chinner <david@xxxxxxxxxxxxx> wrote: > > > > > We do need to decide on the di_uid that comes back from bulkstat. > > > > > Right now it is returning on disk (== init_user_ns) uids. It looks > > > > > to me like xfsrestore is using the normal vfs routines (chown, > > I might not be helpful here, (as despite having used xfs for years > I've not used these features) but feel like I should try based on > what I see in the manpages. Here is my understanding: > > Assume you're a task in a child userns, where you have host uids > 100000-110000 mapped to container uids 0-10000, > > 1. bulkstat is an xfs_ioctl command, right? It should return the mapped > uids (0-10000). > > 2. xfsdump should store the uids as seen in the caller's namespace. If > xfsdump is done from the container, the dump should show uids 0-10000. So when run from within a namespace, it should filter and return only inodes that match the uids/gids mapped into the namespace? That can be done, it's just a rather inefficient use of bulkstat (which is primarily there for efficiency reasons). Here's a corner case. Say I download a tarball from somewhere that has uids/gids inside it, and when I untar it it creates uids/gids outside the namespaces mapped range of [0-10000]. What happens then? What uids do we end up on disk, and how do we ensure that the bulkstat filter still returns those inodes? > 3. xfsrestore should use be run from the desired namespace. If you did > xfsdump from the host ns, you should then xfsrestore from the host ns. > Then inside the container those uids (100000-110000) will be mapped > to your uids (0-10000). > > 4. If you xfsdump in this container, then xfsrestore in another > container where you have 200000-210000 mapped to 0-10000, the dump > image will have uids 0-10000. The restored image will have container > uids 0-10000, while on the underlying host media it will be uids > 200000-210000. > > 5. If you xfsdump in this container then xfsrestore on the host, then > the host uids 0-10000 will be used on the underlying media. The > container would be unable to read this files as the uids do not map > into the container. Yes, that follows from 1+2. We'll need some documentation in the dump/restore man pages for this, and I'd suggest that the namespace documentation/man pages get this sort of treatment, too. Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
