Re: [PATCH v3 1/7] iversion: update comments with info about atime updates

On Tue, Aug 30, 2022 at 01:02:50PM -0400, Jeff Layton wrote:

The fact that NFS kept this more loosely-defined is what allowed us to
elide some of the i_version bumps and regain a fair bit of performance
for local filesystems [1]. If the change attribute had been more
strictly defined like you mention, then that particular optimization
would not have been possible.

This sort of thing is why I'm a fan of not defining this any more
strictly than we require. Later on, maybe we'll come up with a way for
filesystems to advertise that they can offer stronger guarantees.

Yeah, the afs change-attribute-as-counter thing seems ambitious--I
wouldn't even know how to define what exactly you're counting.

My one question is whether it'd be worth just defining the thing as
*increasing*.  That's a lower bar.

(Though admittedly we don't quite manage it now--see again 1631087ba872
"Revert "nfsd4: support change_attr_type attribute"".)

--b.