This has been done. Why re-invent the wheel? (Score -1, Troll)

There are several systems that will allow this functionality already; one of the more notable is CONESE CONtrol of Encrypted Secure Enterprises.

CODA or NFS even solve everything that you might want to do with filesystems. NFS is by no means solid but it does keep working through things like network outages. You can reboot an NFS server while a file write is taking place. The app will just sit there until the server comes back up, finish the write and carry on as before. CODA, which is getting stable now does some really advanced stuff, like disconnected operation.

While a bit long in the tooth, CONESE was an experimental acadenic file system from back when they were cool. (I think it was devised by a guy named Conese at the University of Naples.) It was written for 2.0, but someone ported it to the 2.2 series, but it has long been abandoned and I don't think it compiles under 2.4.