ocfs2: fix a tiny case that inode can not removed.

ocfs2: fix a tiny case that inode can not removed.

When running dirop_fileop_racer we found a case that inode
can not removed.

2 nodes, say Node A and Node B, mount the same ocfs2 volume. Create
two dirs /race/1/ and /race/2/ in the filesystem.

Node A                            Node B
rm -r /race/2/
                                  mv /race/1/ /race/2/
call ocfs2_unlink(), get
the EX mode of /race/2/
                                  wait for B unlock /race/2/
decrease i_nlink of /race/2/ to 0,
and add inode of /race/2/ into
orphan dir, unlock /race/2/
                                  got EX mode of /race/2/. because
                                  /race/1/ is dir, so inc i_nlink
                                  of /race/2/ and update into disk,
                                  unlock /race/2/
because i_nlink of /race/2/
is not zero, this inode will
always remain in orphan dir

This patch fixes this case by test whether i_nlink of new dir is zero.

Signed-off-by: Yiwen Jiang <jiangyiwen@huawei.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>