Re: dm-cache questions

[Mike Snitzer <snitzer@redhat.com>]

On Wed, Dec 11 2013 at  9:14pm -0500,
Paul B. Henson <henson@acm.org> wrote:

> > From: Mike Snitzer [mailto:snitzer@redhat.com]
> > Sent: Wednesday, December 11, 2013 7:07 AM
> >
> > 3.10 is actively maintained by gregkh as a "longterm" stable kernel so
> > all relevant upstream commits should make their way into that tree:
> 
> Right, but as dm-cache changes over time, with new features or other major
> changes being made relative to the version shipped in 3.10, presumably some
> bug fixes that might get committed to mainline would not apply cleanly to
> 3.10 without some potentially non-negligible backporting effort? I don't
> think gregkh does that himself? So if there was a major bug fix that ideally
> would go back to LTS but couldn't be simply cherry picked, one of the
> dm-cache devs would need to submit a separate commit for 3.10? Or perhaps I
> misunderstand the process.

We sometimes cater to the quirks of a specific stable release's codebase:
http://www.redhat.com/archives/dm-devel/2013-December/msg00018.html

Or we add notes to stable for guidance on how to resolve small
differences that'd prevent a clean backport (see bottom of patch
header):
http://www.redhat.com/archives/dm-devel/2013-November/msg00200.html

But in general it is the task of other distro vendors to backport stable
fixes to their products.