ocfs2: add functions to add and remove inode in orphan dir

Add functions to add inode to orphan dir and remove inode in orphan dir.
Here we do not call ocfs2_prepare_orphan_dir and ocfs2_orphan_add
directly.  Because append O_DIRECT will add inode to orphan two and may
result in more than one orphan entry for the same inode.

[akpm@linux-foundation.org: avoid dynamic stack allocation]
Signed-off-by: Joseph Qi <joseph.qi@huawei.com>
Cc: Weiwei Wang <wangww631@huawei.com>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Xuejiufei <xuejiufei@huawei.com>
Cc: alex chen <alex.chen@huawei.com>
Cc: Fengguang Wu <fengguang.wu@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>