[dm-devel] Re: Snapshot patches (cluster-aware, merge, and shared)

[Mike Snitzer]

On Fri, Sep 11 2009 at  3:45pm -0400,
Jonathan Brassow <jbrassow at redhat.com> wrote:

> I've made it through most of the patches that were in mike's directory
> regarding merging
> (http://people.redhat.com/msnitzer/patches/snapshot-merge/kernel/2.6.31).  Everything compiles and I believe I've moved all the logic to the right places.
> 
> At this point, I have yet to:
> 1) go over the merge patches and ensure I haven't missed/overlooked
> something
> 2) Include changes posted by Mike on 9/11/09 for merge speed-ups
> 3) test
> 4) update headers on my patches
> 5) request ACKs for my patches and put ACKs on remaining merge/shared
> patches
> 
> I'm getting these out a little early so you can see where I'm at and we
> can hopefully make the merge window.


Jon,

I did my best to audit the snapshot-merge patches now that they are
layered on your clusterized exception store patches.  I uncovered a few
things that were missing; can provide details later if you like but the
revised patches tell the tale.  I also ported the merge speed-up patch
(dm-snapshot-merge-use-larger-io-when-merging.patch). All snapshot-merge
patches were compile tested to be bisectable; meaning each patch
compiles and the resulting dm-snapshot.ko loads cleanly.

But unfortunately when I only apply all of your patches (everything up
to the start of the snapshot-merge patches) I'm left with a dm-snapshot
that fails to work properly: snapshot LV fails my ext3 mount LVM
testsuite test that I posted to lvm-devel some weeks ago (sans the 4K
aspect; I didn't actually use the test script; I did the mount/unmount
procedure manually on a 512b sector drive).

I've uploaded a revised copy of your quilt tree here:
http://people.redhat.com/msnitzer/patches/snapshot-merge/kernel_unified/2.6.31/

Here is the diffstat of what I changed (started with your tarball):

 dm-bufio.patch                                                                   |   22 -
 dm-exception-store-merge-methods.patch                                           |    6
 dm-multisnap-fujita-daniel.patch                                                 |   32 +-
 dm-multisnap-mikulas.patch                                                       |  120 +++----
 dm-snapshot-find-merging-snapshot.patch                                          |    2
 dm-snapshot-find-min-chunksize-function.patch                                    |    2
 dm-snapshot-merge-interlock-writes.patch                                         |   57 ++-
 dm-snapshot-merge-make-exceptions-in-other-snapshots-if-remapped-to-origin.patch |    2
 dm-snapshot-merge-make-exceptions-in-other-snapshots-when-merging.patch          |   11
 dm-snapshot-merge-operation.patch                                                |   24 -
 dm-snapshot-merge-redirect-to-origin-if-invalidated.patch                        |    4
 dm-snapshot-merge-track-writes.patch                                             |   39 --
 dm-snapshot-merge-use-larger-io-when-merging.patch                               |  160 ++++++++++
 series                                                                           |    8
 14 files changed, 313 insertions(+), 176 deletions(-)