next phase of tmem into linux-next

Hi Stephen --

Please re-include the following tree into linux-next.  The
commit series is for frontswap, the complement of cleancache
handling swap pages, which is the next phase in tmem.  It also
includes the shim code to Xen tmem for frontswap.  It applies
cleanly on linux-3.0-rc1, but if there are any problems or
you have any questions, please let me know!

git://git.kernel.org/pub/scm/linux/kernel/git/djm/tmem.git#linux-next

Thanks,
Dan