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

[David Teigland <teigland@redhat.com>]

On Wed, Dec 17, 2008 at 03:01:56PM -0500, J. Bruce Fields wrote:
> On Wed, Dec 17, 2008 at 01:14:53PM -0600, David Teigland wrote:
> > Jeff suggested the following patch, which I've tried and it fixes the
> > problem I was seeing.  It passes the original, unmodified file_lock to
> > notify(), instead of the copy which is passed to (and coalesced by)
> > posix_lock_file().  I'm guessing this was reason for having a copy of the
> > file_lock in the first place, but it was just not used correctly.
> 
> Yep, that looks much better.  Though actually I suspect what was really
> intended was to use "flc" for the notifies, and "fl" for the
> posix_lock_file().
> 
> Also, since flc is never actually handed to the posix lock system, I
> think it should be a "shallow" lock copy--so it should be created with
> __locks_copy_lock().  Something like the below?

I left this hanging over the holidays and I'd like to get it wrapped up.
In summary, I think the following is the correct fix:
  http://marc.info/?l=linux-nfs&m=122954145532438&w=2

(I'd like to do the s/locks_copy_lock/__locks_copy_lock/ in a separate
patch since it's not directly related to fixing the bug.)

Bruce suggested that perhaps my patch should swap "fl" and "flc", which
I don't think is correct (and doesn't fix the problem in a test).  Here's
my complicated explanation of that:
  http://marc.info/?l=linux-nfs&m=122954948914263&w=2

Without any further feedback, I'll plan to send my patch soon for 2.6.29.
Thanks,
Dave