Next-generation Linux file systems: NiLFS(2) and exofs (developerWorks)

But you make it sound easy, but it is not. The trick is to use up as much
disk space as possible to store as much history as possible without
degrading performance or risking data loss.

There are lots of attempts at logging-based file systems in the past, but
they all hit a wall when they run out of disk space and need to do garbage
collection efficiently. It is very difficult to get right.