Re: Cleancache and shared filesystems

[Joel Becker <jlbec@evilplan.org>]

On Tue, May 31, 2011 at 07:51:36AM -0700, Dan Magenheimer wrote:
> > Hey Dan,
> > 	Steven makes a good point here.  ocfs2 could also take advantage
> > of local filesystem behavior when running in local mode.
> 
> I guess the semantics need to be more clearly defined
> (or perhaps changed if the shared-fs community wants),
> but if cleancache_init_shared_fs is called only by
> a single node, cleancache still enables all the same
> functionality** as cleancache_init_fs. 

	I don't see the ** reference in the footnotes ;-)  You're saying
that, for a single caller, you will properly keep the pagecache bits
around in cleancache as you shrink the balloon and give them back when
requested?  So an ocfs2 calling cleancache_init_share_fs() in only one
VM will have the same page lifetimes (including life inside cleancache
but not in guest pagecache) as a similar ext3?  If so, there are no
changes needed at all.

> I'm not sure I fully understand the semantics of
> local mode though, so please clarify if you think
> I am wrong or misunderstanding your point.

	ocfs2 local mode means that it is not a cluster filesystem.  The
cluster services are not enabled, and ocfs2 behaves like xfs/extN/btrfs.

Joel

-- 

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			jlbec@evilplan.org