There aren’t official reiser4 patches for .20 or .21. There are quite a few branches that contain support for reiser4, but these are highly unstable. (for instance the -mm tree). Also because I wanted to give stacked git a shot, I started my own kernel tree:
One big bzip2-ed diff: bw-for-2.6.21.diff.bz2.
bzip2-ed tar with the separate patches: bw-for-2.6.21.tar.bz2.
This release contains reiser4, suspend2, the gentoo patches and a few patches to get everything working together nicely.