> 
> In terms of getting to this, I think I'd much prefer moving to internal 
> locking.

I'd vote for that, I think. Does internal and
advisory/non-exclusive mean the same thing?

> One of the bigest problems I encountered when getting layered 
> file systems working was ambiguity in what was was happeneing with 
> locking. So I pushed everything to use exclusive real locks; to be 
> consistent (and a bit facist). If we go to making locks advisory, I'm 
> concerned that things would get ambiguous again, and we're back in a mess. 

That helps explain things a lot. Thank you.
I don't know anything about the layered file
system stuff, but now I know what to worry about.
I'll bet that's a good -- and illuminating -- war story.

I was about to ask if VOP_LOCK/VOP_LEASE/VOP_WRITE/VOP_UNLOCK
sequences, and the like, are a concern. But I just checked and
the VOP_LEASE is before the vn_lock() in vn_write().

Regards,
	-gww