From 2b7dbe4bd5872ae5c6780e1a4121c2a5a8401e7c Mon Sep 17 00:00:00 2001
From: Andres Freund <andres@anarazel.de>
Date: Fri, 21 Jan 2022 11:22:55 -0800
Subject: [PATCH] fsync pg_logical/mappings in CheckPointLogicalRewriteHeap().

While individual logical rewrite files were synced to disk, the directory was
not. On some filesystems that could lead to loosing directory entries after a
crash.

Reported-By: Tom Lane <tgl@sss.pgh.pa.us>
Author: Nathan Bossart <bossartn@amazon.com>
Discussion: https://postgr.es/m/867F2E29-2782-4869-970E-B984C6D35A8F@amazon.com
Backpatch: 10-
---
 src/backend/access/heap/rewriteheap.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/backend/access/heap/rewriteheap.c b/src/backend/access/heap/rewriteheap.c
index 1aff62cd42..15bef9f7d3 100644
--- a/src/backend/access/heap/rewriteheap.c
+++ b/src/backend/access/heap/rewriteheap.c
@@ -1289,4 +1289,7 @@ CheckPointLogicalRewriteHeap(void)
 		}
 	}
 	FreeDir(mappings_dir);
+
+	/* persist directory entries to disk */
+	fsync_fname("pg_logical/mappings", true);
 }