Re: [PATCH] lockd: handle fl_grant callbacks with coalesced locks (RFC)

[Jeff Layton <jlayton@redhat.com>]

On Mon, 24 Nov 2008 12:06:53 -0500
"J. Bruce Fields" <bfields@fieldses.org> wrote:

> 
> I still haven't looked at the code yet.  Probably the first thing I'd
> check would whether the previous code depends on an assumption that each
> grant request results in revisit of exactly one rpc.  I can't see a
> problem.
> 

That's the case with the existing code, since it stops looking for
blocks once it finds a match. The patch I sent changes
nlmsvc_grant_deferred to walk the entire list and set up matching
blocks to be granted.

I think at that point, lockd will rewalk the list (via
nlmsvc_retry_blocked) and revisit each one that got moved to the head
of the list. Please correct me if I'm wrong here though. This code has
a lot of indirection and I'm not sure I fully understand the way
revisits work.

As a side note, one thing that might be nice for this is to have
nlmsvc_grant_deferred to only walk the list of blocks that is
associated with this file. nlm_blocked is an ordered list though, so
I'm not sure whether this might have an effect on "fairness" when
several hosts or processes are contending for the same range.

-- 
Jeff Layton <jlayton@redhat.com>