bcachefs: Fix building of aux search trees

We weren't packing the min/max keys, which was a major oversight and
completely disabled generating bkey_floats for adjacent nodes.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/bset.c

@@ -674,17 +674,21 @@ static void make_bfloat(struct btree *b, struct bset_tree *t,
 
 	if (is_power_of_2(j) &&
 	    !min_key->u64s) {
+		if (!bkey_pack_pos(min_key, b->data->min_key, b)) {
 			k = (void *) min_key;
 			bkey_init(&k->k);
 			k->k.p = b->data->min_key;
 		}
+	}
 
 	if (is_power_of_2(j + 1) &&
 	    !max_key->u64s) {
+		if (!bkey_pack_pos(max_key, b->data->max_key, b)) {
 			k = (void *) max_key;
 			bkey_init(&k->k);
 			k->k.p = t->max_key;
 		}
+	}
 
 	__make_bfloat(b, t, j, min_key, max_key);
 }
@@ -768,10 +772,15 @@ static noinline void __build_ro_aux_tree(struct btree *b, struct bset_tree *t)
 
 	t->max_key = bkey_unpack_pos(b, prev);
 
+	if (!bkey_pack_pos(bkey_to_packed(&min_key), b->data->min_key, b)) {
 		bkey_init(&min_key.k);
 		min_key.k.p = b->data->min_key;
+	}
+
+	if (!bkey_pack_pos(bkey_to_packed(&max_key), b->data->max_key, b)) {
 		bkey_init(&max_key.k);
 		max_key.k.p = t->max_key;
+	}
 
 	/* Then we build the tree */
 	eytzinger1_for_each(j, t->size)