bcachefs: Fix btree key cache coherency during replay

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/btree_key_cache.c

@@ -380,9 +380,11 @@ static int btree_key_cache_fill(struct btree_trans *trans,
 	struct bkey_i *new_k = NULL;
 	int ret;
 
-	k = bch2_bkey_get_iter(trans, &iter, ck->key.btree_id, ck->key.pos,
+	bch2_trans_iter_init(trans, &iter, ck->key.btree_id, ck->key.pos,
 			     BTREE_ITER_KEY_CACHE_FILL|
 			     BTREE_ITER_CACHED_NOFILL);
+	iter.flags &= ~BTREE_ITER_WITH_JOURNAL;
+	k = bch2_btree_iter_peek_slot(&iter);
 	ret = bkey_err(k);
 	if (ret)
 		goto err;

fs/bcachefs/btree_update.c

@@ -452,7 +452,7 @@ bch2_trans_update_by_path(struct btree_trans *trans, btree_path_idx_t path_idx,
 	 * the key cache - but the key has to exist in the btree for that to
 	 * work:
 	 */
-	if (path->cached && bkey_deleted(&i->old_k))
+	if (path->cached && !i->old_btree_u64s)
 		return flush_new_cached_update(trans, i, flags, ip);
 
 	return 0;