bch_bbio_free
void bch_bbio_free(struct bio *bio, struct cache_set *c);
bch_bbio_free(bio, b->c);
bch_bbio_free(b->bio, b->c);
bch_bbio_free(bio, b->c);
bch_bbio_free(bio, c);
bch_bbio_free(bio, ca->set);