Neil,
This is another attempt to make raid5 stripe handling multi-threading.
Recent workqueue improvement for unbound workqueue looks very promising to the
raid5 usage. I had details in the first patch.
The patches are against your tree with patch 'raid5: make release_stripe
lockless' and 'raid5: fix stripe release order' but without 'raid5: create
multiple threads to handle stripes'
Thanks,
Shaohua