From 87a6fa9b8d478504b0a4323a3e104b353a239f1a Mon Sep 17 00:00:00 2001
From: Andres Freund <andres@anarazel.de>
Date: Mon, 21 May 2018 15:43:30 -0700
Subject: [PATCH v2 3/6] Make FileGetRawDesc() ensure there's an associated
 kernel FD.

Author: Andres Freund
Reviewed-By:
Discussion: https://postgr.es/m/
Backpatch:
---
 src/backend/storage/file/fd.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/backend/storage/file/fd.c b/src/backend/storage/file/fd.c
index 65e46483a44..8ae13a51ec1 100644
--- a/src/backend/storage/file/fd.c
+++ b/src/backend/storage/file/fd.c
@@ -2232,6 +2232,10 @@ int
 FileGetRawDesc(File file)
 {
 	Assert(FileIsValid(file));
+
+	if (FileAccess(file))
+		return -1;
+
 	return VfdCache[file].fd;
 }
 
-- 
2.17.0.rc1.dirty