+struct extent_end {
+ u32 snapshot;
+ u64 offset;
+ struct snapshots_seen seen;
+};
+
+typedef DARRAY(struct extent_end) extent_ends;
+
+static int check_overlapping_extents(struct btree_trans *trans,
+ struct snapshots_seen *seen,
+ extent_ends *extent_ends,
+ struct bkey_s_c k,
+ struct btree_iter *iter)
+{
+ struct bch_fs *c = trans->c;
+ struct extent_end *i;
+ struct printbuf buf = PRINTBUF;
+ int ret = 0;
+
+ darray_for_each(*extent_ends, i) {
+ /* duplicate, due to transaction restart: */
+ if (i->offset == k.k->p.offset &&
+ i->snapshot == k.k->p.snapshot)
+ continue;
+
+ if (!ref_visible2(c,
+ k.k->p.snapshot, seen,
+ i->snapshot, &i->seen))
+ continue;
+
+ if (fsck_err_on(i->offset > bkey_start_offset(k.k), c,
+ "overlapping extents: extent in snapshot %u ends at %llu overlaps with\n%s",
+ i->snapshot,
+ i->offset,
+ (printbuf_reset(&buf),
+ bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
+ struct bkey_i *update = bch2_trans_kmalloc(trans, bkey_bytes(k.k));
+ if ((ret = PTR_ERR_OR_ZERO(update)))
+ goto err;
+ bkey_reassemble(update, k);
+ ret = bch2_trans_update_extent(trans, iter, update, 0);
+ if (!ret)
+ goto err;
+ }
+ }
+err:
+fsck_err:
+ printbuf_exit(&buf);
+ return ret;
+}
+
+static int extent_ends_at(extent_ends *extent_ends,
+ struct snapshots_seen *seen,
+ struct bkey_s_c k)
+{
+ struct extent_end *i, n = (struct extent_end) {
+ .snapshot = k.k->p.snapshot,
+ .offset = k.k->p.offset,
+ .seen = *seen,
+ };
+
+ n.seen.ids.data = kmemdup(seen->ids.data,
+ sizeof(seen->ids.data[0]) * seen->ids.size,
+ GFP_KERNEL);
+ if (!n.seen.ids.data)
+ return -ENOMEM;
+
+ darray_for_each(*extent_ends, i) {
+ if (i->snapshot == k.k->p.snapshot) {
+ snapshots_seen_exit(&i->seen);
+ *i = n;
+ return 0;
+ }
+
+ if (i->snapshot >= k.k->p.snapshot)
+ break;
+ }
+
+ return darray_insert_item(extent_ends, i - extent_ends->data, n);
+}
+
+static void extent_ends_reset(extent_ends *extent_ends)
+{
+ struct extent_end *i;
+
+ darray_for_each(*extent_ends, i)
+ snapshots_seen_exit(&i->seen);
+
+ extent_ends->nr = 0;
+}
+