ocfs2_get_refcount_tree
ret = ocfs2_get_refcount_tree(OCFS2_SB(inode->i_sb), ref_blkno, &tree);
ret = ocfs2_get_refcount_tree(OCFS2_SB(inode->i_sb),
ret = ocfs2_get_refcount_tree(osb, ref_blkno, &tree);