inode dirty management and reference count

Hi,

Those patches are bug fixes in xattr.c and writeback.c.

And those add the deferred ileaf update for inode number allocation.  It
defers the ileaf update (this is only for inum allocation) until backend
for atomic-commit. To do it, this allows the inode doesn't have the data
btree, and at the first write, allocate btree.

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

Please review, and pull if ok.

Thanks.
--

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