Re: Replace lockmgr for vnodes

[David Holland <dholland-tech%netbsd.org@localhost>]

On Tue, Feb 26, 2008 at 12:53:16PM +0900, YAMAMOTO Takashi wrote:
 > > I believe the vnode locks should not exist at all.  (It should all be  
 > > pushed down into individual file systems.)
 > 
 > i agree.

I am still not convinced of this, for two reasons: first, I don't
think layers are going to work unless locks are exported and shared;
and second, if every fs does its own locking, it gives every fs the
opportunity to do it wrong, and there'll furthermore tend to be a lot
of cut&paste code with all the attendant problems.

I think the long-term solution is to have vfs and/or genfs provide
locking on an optional basis for fses that don't have any real need to
roll their own. I have some ideas about how to do this without causing
the whole situation to get completely out of hand, but said ideas
aren't ready for primetime yet.


(...besides, even if not exported, there'll still be vnode locks.)

-- 
David A. Holland
dholland%netbsd.org@localhost