-- Minimal repro: v3/v4 ROLLBACK of N FILEOPS operations costs ~N x (fsync of
-- the file + fsync of its parent directory), applied inline before ROLLBACK
-- returns (fileops_sync_inverse() after every inverse). Same with crash-loser
-- undo before the cluster opens.  Run with psql against a v4 build:
--   CREATE EXTENSION test_fileops;   then \i this file, once with fsync=on and
--   once after ALTER SYSTEM SET fsync=off; SELECT pg_reload_conf();
-- Measured (NVMe, btrfs), N=1000: v2 1.9 ms | v4 (no cassert) 638 ms with
-- fsync=on, 1.4 ms with fsync=off.
SELECT test_fileops_create_tempfile('fsync_repro.dat') AS f \gset
BEGIN;
SELECT count(test_fileops_chmod(:'f', 384 + (g % 2) * 36)) FROM generate_series(1, 1000) g;
\timing on
ROLLBACK;
\timing off