From 87eadd7e3d6f5581d5b4cb8083212a323050e388 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Wed, 8 Dec 2010 20:01:14 -0500 Subject: Force default wal_sync_method to be fdatasync on Linux. Recent versions of the Linux system header files cause xlogdefs.h to believe that open_datasync should be the default sync method, whereas formerly fdatasync was the default on Linux. open_datasync is a bad choice, first because it doesn't actually outperform fdatasync (in fact the reverse), and second because we try to use O_DIRECT with it, causing failures on certain filesystems (e.g., ext4 with data=journal option). This part of the patch is largely per a proposal from Marti Raudsepp. More extensive changes are likely to follow in HEAD, but this is as much change as we want to back-patch. Also clean up confusing code and incorrect documentation surrounding the fsync_writethrough option. Those changes shouldn't result in any actual behavioral change, but I chose to back-patch them anyway to keep the branches looking similar in this area. In 9.0 and HEAD, also do some copy-editing on the WAL Reliability documentation section. Back-patch to all supported branches, since any of them might get used on modern Linux versions. --- src/backend/storage/file/fd.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'src/backend/storage/file/fd.c') diff --git a/src/backend/storage/file/fd.c b/src/backend/storage/file/fd.c index 89a2d4ae24a..613834eb96d 100644 --- a/src/backend/storage/file/fd.c +++ b/src/backend/storage/file/fd.c @@ -257,12 +257,13 @@ static void RemovePgTempFilesInDir(const char *tmpdirname); int pg_fsync(int fd) { -#ifndef HAVE_FSYNC_WRITETHROUGH_ONLY - if (sync_method != SYNC_METHOD_FSYNC_WRITETHROUGH) - return pg_fsync_no_writethrough(fd); + /* #if is to skip the sync_method test if there's no need for it */ +#if defined(HAVE_FSYNC_WRITETHROUGH) && !defined(FSYNC_WRITETHROUGH_IS_FSYNC) + if (sync_method == SYNC_METHOD_FSYNC_WRITETHROUGH) + return pg_fsync_writethrough(fd); else #endif - return pg_fsync_writethrough(fd); + return pg_fsync_no_writethrough(fd); } -- cgit v1.2.3