Complex sentence: Later, Joe Thornber, Heinz Mauelshagen and Mike Snitzer got their own take on the concept, resulting in inclusion of dm-cache into the Linux kernel mainline; it was merged in kernel version 3.9, released on 28 April 2013.
Split into simpler sentences: Later, Joe Thornber, Heinz Mauelshagen and Mike Snitzer got their own take on the concept included in the mainline Linux kernel. It was merged into the Linux kernel mainline in kernel version 3.9, released on 28 April 2013.