On Thu, 2 Sep 2010, Valerie Aurora wrote: > > Missing: > > > > - upgrade credentials for copy-up > > - ensure that filesystems part of the union are not modified outside > > the union > > Just a note that the infrastructure I wrote to do this last bullet > point for union mounts (hard read-only count plus mount checks) is > completely compatible with hybrid union fs. Thanks. I've used some infrastructure (like parts of the copy up code) from union mounts. One way to generalize the read-only counts infrastructure is not to require MS_RDONLY on the superblock, but count the number of read-write mounts of the sb. If it's zero then that's equivalent to MS_RDONLY. For the writable layer the same can be used, except the overlay filesystem can get a single private read-write mount. This means that the upper layer can also be mounted multiple times, but cannot be part of other unions and cannot be mounted read write to userspace. Thanks, Miklos -- 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
