From 769fd9d8e06bf862334a0e04134a3d2c665e5e5b Mon Sep 17 00:00:00 2001
From: Andres Freund <andres@anarazel.de>
Date: Thu, 8 Sep 2016 16:51:09 -0700
Subject: [PATCH] Fix mdtruncate() to close fd.c handle of deleted segments.

mdtruncate() forgot to FileClose() a segment's mdfd_vfd, when deleting
it. That lead to a fd.c handle to a truncated file being kept open until
backend exit.

The issue appears to have been introduced way back in 1a5c450f3024ac5,
before that the handle was closed inside FileUnlink().

The impact of this bug is limited - only VACUUM and ON COMMIT TRUNCATE
for temporary tables, truncate files in place (i.e. TRUNCATE itself is
not affected), and the relation has to be bigger than 1GB. The
consequences of a leaked fd.c handle aren't severe either.

Discussion: <20160908220748.oqh37ukwqqncbl3n@alap3.anarazel.de>
Backpatch: all supported releases
---
 src/backend/storage/smgr/md.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/backend/storage/smgr/md.c b/src/backend/storage/smgr/md.c
index 1287142918..a94828b32c 100644
--- a/src/backend/storage/smgr/md.c
+++ b/src/backend/storage/smgr/md.c
@@ -976,6 +976,7 @@ mdtruncate(SMgrRelation reln, ForkNumber forknum, BlockNumber nblocks)
 			v = v->mdfd_chain;
 			Assert(ov != reln->md_fd[forknum]); /* we never drop the 1st
 												 * segment */
+			FileClose(ov->mdfd_vfd);
 			pfree(ov);
 		}
 		else if (priorblocks + ((BlockNumber) RELSEG_SIZE) > nblocks)
-- 
2.39.5

