Revert "fs: ext4,fuse changes"

This reverts commit 46cb874bee67c7cfab286e132de0576043968f59.
Revert "epoll: optimize EPOLL_CTL_DEL using rcu"

This reverts commit 3c9e5d128b0b6d2df0268990b80cdc131596097d.
Revert "backport SLUB from Linux 3.3 (thanks to faux123)"

This reverts commit 77ded66f0cf51bf5a146250db2948276dac24a56.