The VPS I manage uses a simple hard link rsync archive daily backup system saved to a loop file. This is great, because each backup only takes up as much space as what has changed each day, and all user/group permissions are kept.

I would like to give users direct access to their home directories in each backup, but I'm worried about intentional or accidental backup data destruction, as how it stands now users can actually change, destroy or add to backed up data they originally owned. I've been looking for a way to mount this filesystem similar to an ro mount option, but something that would still allow rw access to root, but I've had absolutely no luck. In other words, I want users to be able to view and copy their backed up data without actually being able to change it, and have that data maintain the original permissions.

I've got no real preferences as far as filesystem, as long as it's a standard unix filesystem that can preserve permissions, support hard links and deny write access to users without actually stripping the w permission from everything.