diff --git a/src/backend/utils/init/miscinit.c b/src/backend/utils/init/miscinit.c
index e6b6676706..973f584067 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 1.184 2010/04/20 23:48:47 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/init/miscinit.c,v 1.185 2010/08/16 17:32:46 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -818,6 +818,9 @@ 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)
 		{
@@ -881,7 +884,18 @@ 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;
 
@@ -1042,7 +1056,14 @@ 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(),