I checked in a completely untested prototype of dwalk_pack, the purpose
of which is to pack extents into the (somewhat tricky) dleaf format one
at a time, with the aim of presenting a much simpler interface to users
of dleaves (inode.c) than editing the dleaf format directly:
http://tux3.org/tux3?fd=4ef501450a04;file=user/test/dleaf.c
Anybody want to take a run at writing some unit testing code for this,
similar to the existing unit test for dwalk_next? I am sure dwalk_pack
mostly ...
