bch_bbio_endio
void bch_bbio_endio(struct cache_set *c, struct bio *bio,
bch_bbio_endio(io->op.c, bio, bio->bi_status, "reading data to move");
bch_bbio_endio(op->c, bio, bio->bi_status, "writing data to cache");
bch_bbio_endio(s->iop.c, bio, bio->bi_status, "reading from cache");