Re: [pnfs] [PATCH] nfsd: use nfs client rpc callback program

[Benny Halevy <bhalevy@panasas.com>]

On 09/24/2008 9:49:34 pm +0300, "J. Bruce Fields" <bfields@fieldses.org> wrote:
> On Wed, Sep 24, 2008 at 02:42:25PM -0400, Trond Myklebust wrote:
>> On Wed, 2008-09-24 at 13:42 -0400, J. Bruce Fields wrote:
>>
>>> If by "broken" you mean, "introduces a new kernel bug", I don't see it.
>> I mean it introduces utterly unnecessary complications that may return
>> to bite us in the arse at a future time.
> 
> OK, that's the answer I was looking for, thanks.
> 
>> Remember how we once said that it would never make sense for child
>> clones to call the portmapper, and so we added the BUG_ON() in
>> rpcb_getport_async; well guess what, we currently have a bug to fix...
> 
> No, I don't remember that.  But yes, I can see how in general this sort
> of thing could make the code harder to maintain.
> 
>> One pretty obvious fix is to simply move the release method so that it
>> doesn't occur when you release a child. The disadvantage is that a child
>> may then not change its program to one that requires a release method
>> (do we need that?).
> 
> I doubt we need that, but...
> 
>> Another fix would be to add a refcount to the rpc_program structure...
> 
> ... a refcount seems more straightforward.  Benny, what do you think?

I agree.  I'll send a patch hopefully tomorrow.
Would you like that combined with the one I sent or as a separate one?
(I'm inclined towards the latter).

One more thing that seems to need fixing is rpc_bind_new_program
which now uses the passed-in program->cl_stats but doesn't point
to the passed-in program, but rather it only extracts its
name, number, and stats.
Since program->stats may possibly go away with the program
in the refcounted world I think we should get a reference on the
program here too.

That observed, it may also be a good idea to get rid of clnt->cl_stats
altogether and use clnt->program->stats instead to prevent any
discrepancy.

Benny

> 
> --b.