bcachefs: Don't generate alloc updates to invalid buckets

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

Author: Kent Overstreet

fs/bcachefs/buckets.c

@@ -604,6 +604,13 @@ static int bch2_trigger_pointer(struct btree_trans *trans,
 	}
 
 	struct bpos bucket = PTR_BUCKET_POS(ca, &p.ptr);
+	if (!bucket_valid(ca, bucket.offset)) {
+		if (insert) {
+			bch2_dev_bucket_missing(ca, bucket.offset);
+			ret = -BCH_ERR_trigger_pointer;
+		}
+		goto err;
+	}
 
 	if (flags & BTREE_TRIGGER_transactional) {
 		struct bkey_i_alloc_v4 *a = bch2_trans_start_alloc_update(trans, bucket, 0);