The main addition here is a long-desired target framework to allow an SSD to be used as a cache in front of a slower device. Cache tuning is delegated to interchangeable policy modules so these can be developed independently of the mechanics needed to shuffle the data around. Other than that, kcopyd users acquire a throttling parameter, ioctl buffer usage gets streamlined, more mempool reliance is reduced and there are a few other bug fixes and tidy-ups.