The SELinux handbook should include a section on setting the correct context for a swapfile, in case the user doesn't have a dedicated swap partition. The necessary command appears to be "chcon -t swapfile_t [filename]". Since swapfile_t is a customizable type, it will be preserved during a relabel, unless the user explicitly requests that customizable types be reset. Because of this, it may be necessary to drop the "-r" on the rlpkg commands in the SELinux handbook. I'm not convinced that they're necessary anyway, since the user won't have labeled anything with a customizable type at this point in the conversion process.
Added to hardened-docs overlay. I chose to use ~# semanage fcontext -a -t swapfile_t "/swapfile" ~# restorecon /swapfile instead, so that even when a full file system relabelling (including customizable types) is done, the setting is still preserved.
Its at http://www.gentoo.org/proj/en/hardened/selinux/selinux-handbook.xml?full=1 in "Label the File System" Code listing 2.9
