Ocfs2 devel - Sep 2013 - why ocfs2 quota need call ocfs2_qinfo_lock function before qtree_read_dquot or qtree_write_dquot ?

Hi all,
   I want to know why ocfs2 quota need call ocfs2_qinfo_lock function before
qtree_read_dquot or
qtree_write_dquot in ocfs2_acquire_dquot function.
   I think that it need not, because before ocfs2_qinfo_lock, it has
ocfs2_lock_global_qf, it will
lock the global quota inode.

Thanks,
Jesen.
2013-9-6