++/* copied from fs/buffer.c */
++static void unmap_underlying_metadata(struct buffer_head * bh)
++{
++ struct buffer_head *old_bh;
++
++ old_bh = get_hash_table(bh->b_dev, bh->b_blocknr, bh->b_size);
++ if (old_bh) {
++ mark_buffer_clean(old_bh);
++ wait_on_buffer(old_bh);
++ clear_bit(BH_Req, &old_bh->b_state);
++ __brelse(old_bh);
++ }
++}
++