+ ret = check_pos_snapshot_overwritten(trans, btree_id, k.k->p);
+ if (ret < 0)
+ goto err;
+ if (ret)
+ goto nomerge1;
+
+ update = bch2_trans_kmalloc(trans, bkey_bytes(k.k));
+ if ((ret = PTR_ERR_OR_ZERO(update)))
+ goto err;
+
+ bkey_reassemble(update, k);
+
+ if (bch2_bkey_merge(c, bkey_i_to_s(update), bkey_i_to_s_c(insert))) {
+ ret = bch2_btree_delete_at(trans, &iter, flags);
+ if (ret)
+ goto err;
+
+ insert = update;
+ goto next;
+ }
+ }
+nomerge1:
+ ret = 0;
+ if (!bkey_cmp(k.k->p, start))
+ goto next;
+
+ while (bkey_cmp(insert->k.p, bkey_start_pos(k.k)) > 0) {
+ bool front_split = bkey_cmp(bkey_start_pos(k.k), start) < 0;
+ bool back_split = bkey_cmp(k.k->p, insert->k.p) > 0;
+
+ /*
+ * If we're going to be splitting a compressed extent, note it
+ * so that __bch2_trans_commit() can increase our disk
+ * reservation:
+ */
+ if (((front_split && back_split) ||
+ ((front_split || back_split) && k.k->p.snapshot != insert->k.p.snapshot)) &&
+ (compressed_sectors = bch2_bkey_sectors_compressed(k)))
+ trans->extra_journal_res += compressed_sectors;
+
+ if (front_split) {
+ update = bch2_trans_kmalloc(trans, bkey_bytes(k.k));
+ if ((ret = PTR_ERR_OR_ZERO(update)))
+ goto err;
+
+ bkey_reassemble(update, k);
+
+ bch2_cut_back(start, update);
+
+ bch2_trans_iter_init(trans, &update_iter, btree_id, update->k.p,
+ BTREE_ITER_NOT_EXTENTS|
+ BTREE_ITER_ALL_SNAPSHOTS|
+ BTREE_ITER_INTENT);
+ ret = bch2_btree_iter_traverse(&update_iter) ?:
+ bch2_trans_update(trans, &update_iter, update,
+ BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE|
+ flags);
+ bch2_trans_iter_exit(trans, &update_iter);
+
+ if (ret)
+ goto err;
+ }
+
+ if (k.k->p.snapshot != insert->k.p.snapshot &&
+ (front_split || back_split)) {
+ update = bch2_trans_kmalloc(trans, bkey_bytes(k.k));
+ if ((ret = PTR_ERR_OR_ZERO(update)))
+ goto err;
+
+ bkey_reassemble(update, k);
+
+ bch2_cut_front(start, update);
+ bch2_cut_back(insert->k.p, update);
+
+ bch2_trans_iter_init(trans, &update_iter, btree_id, update->k.p,
+ BTREE_ITER_NOT_EXTENTS|
+ BTREE_ITER_ALL_SNAPSHOTS|
+ BTREE_ITER_INTENT);
+ ret = bch2_btree_iter_traverse(&update_iter) ?:
+ bch2_trans_update(trans, &update_iter, update,
+ BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE|
+ flags);
+ bch2_trans_iter_exit(trans, &update_iter);
+ if (ret)
+ goto err;
+ }
+
+ if (bkey_cmp(k.k->p, insert->k.p) <= 0) {
+ update = bch2_trans_kmalloc(trans, sizeof(*update));
+ if ((ret = PTR_ERR_OR_ZERO(update)))
+ goto err;
+
+ bkey_init(&update->k);
+ update->k.p = k.k->p;
+
+ if (insert->k.p.snapshot != k.k->p.snapshot) {
+ update->k.p.snapshot = insert->k.p.snapshot;
+ update->k.type = KEY_TYPE_whiteout;
+ }
+
+ bch2_trans_iter_init(trans, &update_iter, btree_id, update->k.p,
+ BTREE_ITER_NOT_EXTENTS|
+ BTREE_ITER_INTENT);
+ ret = bch2_btree_iter_traverse(&update_iter) ?:
+ bch2_trans_update(trans, &update_iter, update,
+ BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE|
+ flags);
+ bch2_trans_iter_exit(trans, &update_iter);
+
+ if (ret)
+ goto err;
+ }
+
+ if (back_split) {
+ update = bch2_trans_kmalloc(trans, bkey_bytes(k.k));
+ if ((ret = PTR_ERR_OR_ZERO(update)))
+ goto err;
+
+ bkey_reassemble(update, k);
+ bch2_cut_front(insert->k.p, update);
+
+ ret = bch2_trans_update_by_path(trans, iter.path, update,
+ BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE|
+ flags);
+ if (ret)
+ goto err;
+ goto out;
+ }
+next:
+ bch2_btree_iter_advance(&iter);
+ k = bch2_btree_iter_peek_upto(&iter, POS(insert->k.p.inode, U64_MAX));
+ if ((ret = bkey_err(k)))
+ goto err;
+ if (!k.k)
+ goto out;
+ }
+
+ if (bch2_bkey_maybe_mergable(&insert->k, k.k)) {
+ ret = check_pos_snapshot_overwritten(trans, btree_id, insert->k.p);
+ if (ret < 0)
+ goto err;
+ if (ret)
+ goto nomerge2;
+
+ ret = check_pos_snapshot_overwritten(trans, btree_id, k.k->p);
+ if (ret < 0)
+ goto err;
+ if (ret)
+ goto nomerge2;
+
+ bch2_bkey_merge(c, bkey_i_to_s(insert), k);
+ }
+nomerge2:
+ ret = 0;
+out:
+ if (!bkey_deleted(&insert->k)) {
+ /*
+ * Rewinding iterators is expensive: get a new one and the one
+ * that points to the start of insert will be cloned from:
+ */
+ bch2_trans_iter_exit(trans, &iter);
+ bch2_trans_iter_init(trans, &iter, btree_id, insert->k.p,
+ BTREE_ITER_NOT_EXTENTS|
+ BTREE_ITER_INTENT);
+ ret = bch2_btree_iter_traverse(&iter) ?:
+ bch2_trans_update(trans, &iter, insert, flags);
+ }
+err:
+ bch2_trans_iter_exit(trans, &iter);
+
+ return ret;
+}
+
+/*
+ * When deleting, check if we need to emit a whiteout (because we're overwriting
+ * something in an ancestor snapshot)
+ */
+static int need_whiteout_for_snapshot(struct btree_trans *trans,
+ enum btree_id btree_id, struct bpos pos)
+{
+ struct btree_iter iter;
+ struct bkey_s_c k;
+ u32 snapshot = pos.snapshot;
+ int ret;
+
+ if (!bch2_snapshot_parent(trans->c, pos.snapshot))
+ return 0;
+
+ pos.snapshot++;
+
+ for_each_btree_key_norestart(trans, iter, btree_id, pos,
+ BTREE_ITER_ALL_SNAPSHOTS|
+ BTREE_ITER_NOPRESERVE, k, ret) {
+ if (bkey_cmp(k.k->p, pos))
+ break;
+
+ if (bch2_snapshot_is_ancestor(trans->c, snapshot,
+ k.k->p.snapshot)) {
+ ret = !bkey_whiteout(k.k);
+ break;
+ }
+ }
+ bch2_trans_iter_exit(trans, &iter);
+
+ return ret;
+}
+
+static int __must_check
+bch2_trans_update_by_path(struct btree_trans *trans, struct btree_path *path,
+ struct bkey_i *k, enum btree_update_flags flags)
+{
+ struct bch_fs *c = trans->c;
+ struct btree_insert_entry *i, n;
+
+ BUG_ON(!path->should_be_locked);
+
+ BUG_ON(trans->nr_updates >= BTREE_ITER_MAX);
+ BUG_ON(bpos_cmp(k->k.p, path->pos));
+
+ n = (struct btree_insert_entry) {
+ .flags = flags,
+ .bkey_type = __btree_node_type(path->level, path->btree_id),
+ .btree_id = path->btree_id,
+ .level = path->level,
+ .cached = path->cached,
+ .path = path,
+ .k = k,
+ .ip_allocated = _RET_IP_,
+ };
+
+#ifdef CONFIG_BCACHEFS_DEBUG
+ trans_for_each_update(trans, i)
+ BUG_ON(i != trans->updates &&
+ btree_insert_entry_cmp(i - 1, i) >= 0);
+#endif