chunk_to_sector
dest.sector = chunk_to_sector(s->store, old_chunk);
src.sector = chunk_to_sector(s->store, new_chunk);
src.sector = chunk_to_sector(s->store, pe->e.old_chunk);
dest.sector = chunk_to_sector(s->store, pe->e.new_chunk);
chunk_to_sector(s->store, dm_chunk_number(e->new_chunk) +