FILEDESC_LOCK() implementation

[Divacky Roman]

On Mon, Jun 12, 2006 at 07:40:13AM +0000, Poul-Henning Kamp wrote:
> In message <20060612080504.W26634 at fledge.watson.org>, Robert Watson writes:
> 
> >At least in the VFS and socket code, you want a notion of acquiring both and 
> >dropping one, or upgrading/downgrading.  The logic tends to go something like 
> >this:
> 
> That's different from what FILEDESC needs.  FILEDESC has two different
> classes of operations: cheap/non-sleeping and expensive/sleeping

I made a patch: http://hysteria.sk/~neologism/filedesc.patch
which improves the situation on UP, it was even commited but then backed out
because there are places where FILEDESC_[UN]LOC_FAST is used to protect
operations which can sleep...

I think there's just one or two such places but dont have time to work on this
(I am busy with SoC) but is shoudl be quite trivial to find them (the number of
places where we use _FAST locking is not very big)

roman