[Unionfs] unionfs mmap diff

[Erez Zadok]

Are you sure it's against 1.1.3?  If so, why did you reintroduce fist.h?
Make sure your "before" and "after" source trees are clean of old cruft.

For this large patch, we need explanations.  Every fxn you changed, added,
or removed -- why?  Why did you "#if 0" a number of things?

You can stick comments such as "//SP: text..." above each code block you
touched, so we can easily read the explanation of your change along with the
relevant code (and grep out your comments before applying such code :-)

Many thanks.

Erez.