> > talking about mtime, i think it can be noted when the changes are
> > flushed out to backing store.  ie. when we usually notice the dirtiness
> > of the pages.
> > updating mtime in VOP_GETPAGES is somewhat improper, IMO.
> 
> For whatever it's worth, I agree with all of the above.  To restate:
> 
> Update atime on mmap(...PROT_READ...)
> Update mtime when flushing dirty mmapped pages out to backing store.
> 
> I would expect neither more nor less.
> 

NFS clients use mtime to determine whether client-side
cache is valid or stale. A local program reading/mmaping
a file could see a different result than a client reading
the same file because the has mistakenly determined cache
validity because mtime hasn't changed.

Yes, NFS coherency is much more complicated than that.
But I thought it worth pointing out.

Regards,
	-gww