Not much of a surprise really, as the old code worked too, but the updated VMUFAT filesystem code works with 3.2.0-rc7.
Just have to clean it up so it is of an acceptable standard.
Update: In the unlikely event that someone is testing the code I should warn you that the above was overly optimistic. On unmounting the VMUFAT volume the whole kernel crashed – a bug in the
evict_inode function I think.