[dm-devel] Re: [PATCH 1 of 2] DM Exception Store: return zero when empty

[Mike Snitzer]

On Thu, Sep 24 2009 at  8:51am -0400,
Alasdair G Kergon <agk at redhat.com> wrote:

> On Wed, Sep 23, 2009 at 10:24:58AM -0500, Jon Brassow wrote:
> > When the snapshot is empty, return 0 as the number of allocated sectors.
> > This will be needed to properly notify userspace that merging is finished.
> 
> A kernel/userspace interface change and visible to the user in their tools.
> Needs discussion.

I'd be quite surprised if any users' scripts had the intelligence that
the persistent exception store always used the first 2 chunks.

I view this patch as a fix and would like to see it pushed for
2.6.32-rcX

This patch is also a prerequisite for some patches I just posted to
lvm-devel:
http://www.redhat.com/archives/lvm-devel/2009-September/msg00145.html