From e70eea50e81d8f40fb8db15c06b23305d4b8698f Mon Sep 17 00:00:00 2001
From: Nathan Bossart <nathan@postgresql.org>
Date: Wed, 6 Nov 2024 09:52:19 -0600
Subject: [PATCH v1 5/8] Export pre_sync_fname().

THIS IS A PROOF OF CONCEPT AND IS NOT READY FOR SERIOUS REVIEW.

A follow-up commit will use this function to alert the file system
that we want a file's data on disk so that subsequent calls to
fsync() are faster.
---
 src/common/file_utils.c         | 18 +++++-------------
 src/include/common/file_utils.h |  1 +
 2 files changed, 6 insertions(+), 13 deletions(-)

diff --git a/src/common/file_utils.c b/src/common/file_utils.c
index 65cdf07ae7..5c201ec6e8 100644
--- a/src/common/file_utils.c
+++ b/src/common/file_utils.c
@@ -45,10 +45,6 @@
  */
 #define MINIMUM_VERSION_FOR_PG_WAL	100000
 
-#ifdef PG_FLUSH_DATA_WORKS
-static int	pre_sync_fname(const char *fname, bool isdir, void *arg);
-#endif
-
 #ifdef HAVE_SYNCFS
 
 /*
@@ -307,11 +303,7 @@ walkdir(const char *path,
 				 * introduce a huge number of function pointer calls and
 				 * directory reads that we are trying to avoid.
 				 */
-#ifdef PG_FLUSH_DATA_WORKS
 				if ((action != pre_sync_fname && action != fsync_fname) ||
-#else
-				if (action != fsync_fname ||
-#endif
 					!arg || *((bool *) arg) ||
 					strcmp(de->d_name, "base") != 0)
 					walkdir(subpath, action, false, arg);
@@ -348,11 +340,12 @@ walkdir(const char *path,
  * Ignores errors trying to open unreadable files, and reports other errors
  * non-fatally.
  */
-#ifdef PG_FLUSH_DATA_WORKS
-
-static int
+int
 pre_sync_fname(const char *fname, bool isdir, void *arg)
 {
+#ifndef PG_FLUSH_DATA_WORKS
+	return 0;
+#else
 	int			fd;
 
 	fd = open(fname, O_RDONLY | PG_BINARY, 0);
@@ -380,9 +373,8 @@ pre_sync_fname(const char *fname, bool isdir, void *arg)
 
 	(void) close(fd);
 	return 0;
-}
-
 #endif							/* PG_FLUSH_DATA_WORKS */
+}
 
 /*
  * fsync_fname -- Try to fsync a file or directory
diff --git a/src/include/common/file_utils.h b/src/include/common/file_utils.h
index 3743caa63e..e7a34d4c4e 100644
--- a/src/include/common/file_utils.h
+++ b/src/include/common/file_utils.h
@@ -43,6 +43,7 @@ extern int	fsync_parent_path(const char *fname);
 extern void walkdir(const char *path,
 					int (*action) (const char *fname, bool isdir, void *arg),
 					bool process_symlinks, void *arg);
+extern int	pre_sync_fname(const char *fname, bool isdir, void *arg);
 #endif
 
 extern PGFileType get_dirent_type(const char *path,
-- 
2.39.5 (Apple Git-154)