ext3cow
Ext3cow or third extended filesystem with copy-on-write is an open source, versioning file system based on the ext3 file system. Versioning is implemented through block-level copy-on-write. It shares many of its performance characteristics with... Wikipedia
File allocation: bitmap (free space), table (metadata)
File system permissions: Unix permissions, ACLs and arbitrary security attributes (Linux 2.6 and later)
Max file size: 2TiB