ufs code in sfs branch

Ok, a couple of quick notes:

1) It's horribly horribly broken - don't expect it to make much sense yet ;)
I originally started on making small simple changes, and rapidly discovered
that the difference between ufs and aufs is more in-depth than I'd expected,
particularly around the ctrlp structure. So this code is starting down the
path of re-shuffling the requestp structure and the callbacks such that ctrlp
is no longer necessary.

2) The fs_aufs.c file is primarily dealing with ctrlp atm - as per above, that
stuff is all slowly vanishing. fs_ufs.c holds the guts of the various ufs-ish
operations - what goes in what file can change easily, it's more just where I
happen to be when editing various bits atm.

3) The async.c and aiops.c files I've just tossed in there, along with
store_dir_ufs.c, as placeholders to indicate that their functionality and the
bulk of their code is required in there. It all gets a working-over to re-do
the callbacks etc.

4) There's a structure missing from the SwapDir structure, that'll hold the io
function pointers - pointers to the various io_open()-type functions. Thus,
each individual swapdir can be configured to be ufs with async or immediate io
(or, theoretically, diskd) as required.

5) Various small counters are missing or broken, in that they previously
existed across all SD's, I'm moving them into the SD structure itself
(actually, into fsdata), so they're swapdir-specific.

Anyway, if people want to see how it's going to look, there it is.

KevinL

-- 
Internet techie, Obsidian Consulting Group
Specialising in proxy issues and traffic measuring/billing.