> I intend to provide different "views" of the data stored on > btrfs subvolumes. e.g. mount a subvolume in location A rw; > and ro in location B while also overwriting uids, gids, and > permissions. [ ... ]
That's not how UNIX/Linux permissions and ACLs are supposed to work, perhaps you should reconsider such a poor idea. Mount options are provided to map non-UNIX/Linux filesystems into the UNIX/Linux permissions and ACLs in a crude way. If you really want, uid/gid/permissions are an inode property, and Btrfs via "reflinking" allows sharing of file data between different inodes. So you can for example create a RW snapshot of a subvolume, change all ids/permissions/ACLs, and the data space will still be shared. This is not entirely cost-free. If you really really want this it may be doable also with mount namespaces combined with user namespaces, with any filesystem, depending on yoiur requirements: http://man7.org/linux/man-pages/man7/user_namespaces.7.html http://man7.org/linux/man-pages/man7/mount_namespaces.7.html As to mounting multiple times on multiple directories, that is possible with Linux VFS regardless of filesystem type, or by using 'mount --bind' or a variant. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
