Kyle Moffett wrote: > On Jul 15, 2006, at 13:39:50, Al Boldi wrote: > > Trond Myklebust wrote: > >> On Sat, 2006-07-15 at 06:35 -0600, Eric W. Biederman wrote: > >>> I hope the confusion has passed for Trond. My impression was he > >>> figured this was per process data so it didn't make sense any > >>> where near a filesystem, and the superblock was the last place it > >>> should be. > >> > >> You are still using the wrong abstraction. Data that is not global > >> to the entire machine has absolutely _no_ place being put into the > >> superblock. It doesn't matter if it is process-specific, container- > >> specific or whatever-else-specific, it will still be vetoed. > >> > >> If your real problem is uid/gid mapping on top of generic > >> filesystems, then have you looked into the *BSD solution of using > >> a stackable filesystem (i.e. umapfs)? > > > > A stackable FS is really overkill here, when all that is needed is > > a simple mapping. An easy solution would be, to allow for perMount > > Handlers via hooks into the VFS, as was suggested in the '[RFC] > > VFS: FS CoW using redirection' thread. > > IMHO a UID mapping is completely the wrong solution for this. Sure, maybe it is, but if it were needed, why would I implement it using an extra VFS below the VFS? > The problem is the subject (the process) and object (the filesystem) > place different meanings on different UIDs, in other words their UIDs > are in different namespaces. The result is that you should tag that > filesystem (vfsmount, really) with a different namespace tag and fix > the namespace system to properly handle cross-namespace permissions, > not forcibly graft on some fragile mapping system. Grafting is probably the wrong way to implement this too, so what I suggest is to have the VFS provide hooks (aka plug-ins) for perMount Handlers, which would relieve developers from the need to either merge their requirements with the VFS, or introduce a subVFS. This would imply more freedom, while at the same time reducing overhead. > By using the > keyring system for foreign-namespace UID permissions the actual > permissions fall out quite nicely. Maybe it is, for this specific situation. Thanks! -- Al - 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
