inode dirty management and reference count

Hi,

Those patches add the inode dirty management and reference count. I
think those can be used for both of good writeback flush and
atomic-commit.

I guess the issues of this patchset are, iget() is not finding the all
in-core inode (reopen is not allowed, it's same with current though).
And tux3fuse patches are almost untested, sorry.

	static-http://userweb.kernel.org/~hirofumi/tux3/

Please review, and pull if ok.

Thanks.
--

-- 
OGAWA Hirofumi <hirofumi <at> mail.parknet.co.jp>