Re: [PATCH 2/2] nfsd: fix pNFS return on close semantics

[Christoph Hellwig <hch@lst.de>]

On Mon, Apr 27, 2015 at 07:30:08PM -0400, Jeff Layton wrote:
> One thing that might be good to do though is to create a dedicated
> slabcache for these objects. On a pnfs-enabled server, you might end up
> with quite a few of them, so packing them efficiently is probably a good
> thing to do. That's just a refinement though and could be done in a
> later patch.

Also currently we allocate them for any 4.1 server.  Now that I think about
it we should at least make it conditional on CONFIG_NFSD_PNFS, or even
better find a runtime check.

> > (Also: does this need to go to stable?  If we're potentially leaving
> > layouts around forever, this sounds pretty serious.)

We're always returning them on file close, so we're not leaking anything.
The common case is that we actually return them too early when we close
the file but still have an outstanding delegation.

I'm ok with a cc to stable, but it's a bit borderline.  Note that currently
you even applied my two patches to your 4.2 incoming queue, not even 4.1..