MIT 6.824 labs (http://pdos.csail.mit.edu/6.824/labs/index.html).

YFS, standing for "Yet another File System", is a simplified implementation of Frangipani by Thekkath et al.

I am not affilliated with the MIT. While perhaps it passes all the tests, my implementation suffers from low efficiency and depends on several assumptions which might be true for these labs but not ideal for a robust program. So it has no reuse value for production systems. Furthermore, if you are taking 6.824 right now and are doing similar labs, you are not supposed to look at the code here.