bch_keybuf_del
void bch_keybuf_del(struct keybuf *buf, struct keybuf_key *w);
bch_keybuf_del(&i->keys, w);
bch_keybuf_del(&c->moving_gc_keys, w);
bch_keybuf_del(&c->moving_gc_keys, w);
bch_keybuf_del(&io->op.c->moving_gc_keys, io->w);
bch_keybuf_del(&dc->writeback_keys, w);
bch_keybuf_del(&dc->writeback_keys, w);