From e74ced85dc9b6520450d6dbf8ba9cf272c1465db Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Mon, 16 Aug 2010 17:33:01 +0000
Subject: Arrange to fsync the contents of lockfiles (both postmaster.pid and
 the socket lockfile) when writing them.  The lack of an fsync here may well
 explain two different reports we've seen of corrupted lockfile contents,
 which doesn't particularly bother the running server but can prevent a new
 server from starting if the old one crashes.  Per suggestion from Alvaro.

Back-patch to all supported versions.
---
 src/backend/utils/init/miscinit.c | 27 ++++++++++++++++++++++++---
 1 file changed, 24 insertions(+), 3 deletions(-)

(limited to 'src/backend/utils/init/miscinit.c')

diff --git a/src/backend/utils/init/miscinit.c b/src/backend/utils/init/miscinit.c
index 55b395f9a2b..35ef0de709a 100644
--- a/src/backend/utils/init/miscinit.c
+++ b/src/backend/utils/init/miscinit.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/init/miscinit.c,v 1.175.2.1 2009/12/09 21:58:04 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/init/miscinit.c,v 1.175.2.2 2010/08/16 17:33:01 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -879,6 +879,9 @@ CreateLockFile(const char *filename, bool amPostmaster,
 		 * admin) but has left orphan backends behind.	Check for this by
 		 * looking to see if there is an associated shmem segment that is
 		 * still in use.
+		 *
+		 * Note: because postmaster.pid is written in two steps, we might not
+		 * find the shmem ID values in it; we can't treat that as an error.
 		 */
 		if (isDDLock)
 		{
@@ -942,7 +945,18 @@ CreateLockFile(const char *filename, bool amPostmaster,
 				(errcode_for_file_access(),
 				 errmsg("could not write lock file \"%s\": %m", filename)));
 	}
-	if (close(fd))
+	if (pg_fsync(fd) != 0)
+	{
+		int			save_errno = errno;
+
+		close(fd);
+		unlink(filename);
+		errno = save_errno;
+		ereport(FATAL,
+				(errcode_for_file_access(),
+				 errmsg("could not write lock file \"%s\": %m", filename)));
+	}
+	if (close(fd) != 0)
 	{
 		int			save_errno = errno;
 
@@ -1103,7 +1117,14 @@ RecordSharedMemoryInLockFile(unsigned long id1, unsigned long id2)
 		close(fd);
 		return;
 	}
-	if (close(fd))
+	if (pg_fsync(fd) != 0)
+	{
+		ereport(LOG,
+				(errcode_for_file_access(),
+				 errmsg("could not write to file \"%s\": %m",
+						DIRECTORY_LOCK_FILE)));
+	}
+	if (close(fd) != 0)
 	{
 		ereport(LOG,
 				(errcode_for_file_access(),
-- 
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