fs: f2fs: backport to LK 3.2

Signed-off-by: Shilin Victor <chrono.monochrome@gmail.com>
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6

https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/commit/?id=1b8e94993c4752d98c33903aa836acc15f7e6d5c