It’s rather been a while since I’ve worked on the xiafs module, but while I was flying to NYC last week I ended up working on it some on the plane and got it caught up with more the recent Linux kernels.
Specifically, kernel version 4.0.9 still works with the 3.16.4 branch, so there were no changes there. Kernel version 4.1.3 and kernel version 4.4.0 had very small updates, so they have their own branches. I haven’t tested any 4.2 or 4.3 kernels, but I expect they would work with one or the other of those branches.
The usual warnings about this still apply; you’d be crazy to use this on a production box, and while it should work fine it could conceivably blow your computer up or something. Don’t forget the whole 2GB volume/64MB max file size limitation either.