[Ocfs2-devel] [PATCH V3 0/8] Cleancache: overview

[Dan Magenheimer]

> > On Fri, Jul 23, 2010 at 06:58:03AM -0700, Dan Magenheimer wrote:
> > > CHRISTOPH AND ANDREW, if you disagree and your concerns have
> > > not been resolved, please speak up.
> 
> Hi Christoph --
> 
> Thanks very much for the quick (instantaneous?) reply!
> 
> > Anything that need modification of a normal non-shared fs is utterly
> > broken and you'll get a clear NAK, so the propsal before is a good
> > one.
> 
> No, the per-fs opt-in is very sensible; and its design is
> very minimal.

Not to belabor the point, but maybe the right way to think about
this is:

Cleancache is a new optional feature provided by the VFS layer
that potentially dramatically increases page cache effectiveness
for many workloads in many environments at a negligible cost.

Filesystems that are well-behaved and conform to certain restrictions
can utilize cleancache simply by making a call to cleancache_init_fs
at mount time.  Unusual, misbehaving, or poorly layered filesystems
must either add additional hooks and/or undergo extensive additional
testing... or should just not enable the optional cleancache.