xfs_dir2_leafn_order
before = xfs_dir2_leafn_order(dp, old_blk->bp, new_blk->bp);
swap_blocks = xfs_dir2_leafn_order(dp, blk1->bp, blk2->bp);
if (xfs_dir2_leafn_order(dp, save_blk->bp, drop_blk->bp))
extern int xfs_dir2_leafn_order(struct xfs_inode *dp, struct xfs_buf *leaf1_bp,