[PATCH 14/18] nfsd: pNFS block layout driver

[J. Bruce Fields]

On Thu, Jan 08, 2015 at 12:41:31PM -0800, Jeff Layton wrote:
> On Wed, 7 Jan 2015 11:28:02 +0100
> Christoph Hellwig <hch at lst.de> wrote:
> 
> > On Tue, Jan 06, 2015 at 11:42:05AM -0800, Jeff Layton wrote:
> > > Or maybe an "on" switch?
> > > 
> > > We have some patches (not posted currently) that add a "pnfs" export
> > > option. Maybe we should add that and only enable pnfs on exports that
> > > have that option present?
> > 
> > I would defintively prefer the off switch.  I can add one if people want
> > it, but export options are a little annoying as they require support
> > not only in the kernel but also in nfs-utils.
> 
> True, it is a pain, but I think it's realistic to expect someone who
> wants to do pnfs to have an updated nfs-utils. It wouldn't take too
> long for it to trickle out to the various distros and adding new export
> options is fairly simple to do.
> 
> If we do want to go that route, it might be nice to do the option with
> a list of layout types. For example:
> 
>     pnfs=block:file:flexfiles
> 
> ...so we could potentially support more than one layout type per
> export.

I like the goal of making this as close to zero-configuration as
possible, and I'd rather wait for a demonstrated need till we add
per-export or multiple-layout-type configuration.  A global off switch
sounds OK to me.

--b.