I believe drivers/staging should be renamed into fs/staging, since this tree will likely contain <a href="http://marc.info/?l=linux-fsdevel&m=123671134013173&w=2">CEPH</a> and <a href="http://marc.info/?l=linux-fsdevel&m=123671134013171&w=2">NILFS2</a>, as long as <a href="/projects/pohmelfs">POHMELFS</a> and <a href="/projects/dst">DST</a>.

<a href="http://ceph.newdream.net/">Ceph</a> is a distributed file system designed for reliability, scalability, and performance. The storage system consists of some (potentially large) number of storage servers (bricks), a smaller set of metadata server daemons, and a few monitor daemons for managing cluster membership and state.
It relies on <a href="http://btrfs.wiki.kernel.org/index.php/Main_Page">BTRFS</a> to store data and closely works with its internal features like transactions and cloning.

<a href="http://www.nilfs.org/">NILFS2</a> is a log-structured file system supporting versioning of the entire file system and continuous snapshotting which allows users to even restore files mistakenly overwritten or destroyed just a few seconds ago.
NILFS2 lives in -mm tree for a while already, so this actually may be a call for the mainstream inclusion directly into <code>fs/</code>.

More filesystems - good and different!