v3-0001-Remove-fdatasync-configure-probe.patch

From a50957d4c079a3703c9f8074287c7edb5654022c Mon Sep 17 00:00:00 2001
From: Thomas Munro <thomas.munro@gmail.com>
Date: Wed, 20 Jul 2022 14:10:37 +1200
Subject: [PATCH v3] Remove fdatasync configure probe.

Every system we target has POSIX fdatasync, except Windows where we
provide a replacement in src/port/fdatasync.c.  We can remove the
configure probe and associated #ifdefs.

We retain the probe for the function declaration, which allows us to
supply the missing declaration for macOS and Windows.

Discussion: https://postgr.es/m/CA%2BhUKGJZJVO%3DiX%2Beb-PXi2_XS9ZRqnn_4URh0NUQOwt6-_51xQ%40mail.gmail.com
---
 configure                             | 59 +--------------------------
 configure.ac                          |  3 --
 src/backend/access/transam/xlog.c     |  4 --
 src/backend/storage/file/fd.c         |  8 ----
 src/bin/pg_test_fsync/pg_test_fsync.c |  4 --
 src/include/access/xlogdefs.h         |  7 +---
 src/include/pg_config.h.in            |  3 --
 src/include/port/freebsd.h            |  2 -
 src/include/port/win32_port.h         |  8 ----
 src/tools/msvc/Solution.pm            |  1 -
 10 files changed, 3 insertions(+), 96 deletions(-)

diff --git a/configure b/configure
index 33a425562f..f13822fb3d 100755
--- a/configure
+++ b/configure
@@ -12315,63 +12315,6 @@ if test "$ac_res" != no; then :
 
 fi
 
-# Solaris:
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for library containing fdatasync" >&5
-$as_echo_n "checking for library containing fdatasync... " >&6; }
-if ${ac_cv_search_fdatasync+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  ac_func_search_save_LIBS=$LIBS
-cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-
-/* Override any GCC internal prototype to avoid an error.
-   Use char because int might match the return type of a GCC
-   builtin and then its argument prototype would still apply.  */
-#ifdef __cplusplus
-extern "C"
-#endif
-char fdatasync ();
-int
-main ()
-{
-return fdatasync ();
-  ;
-  return 0;
-}
-_ACEOF
-for ac_lib in '' rt posix4; do
-  if test -z "$ac_lib"; then
-    ac_res="none required"
-  else
-    ac_res=-l$ac_lib
-    LIBS="-l$ac_lib  $ac_func_search_save_LIBS"
-  fi
-  if ac_fn_c_try_link "$LINENO"; then :
-  ac_cv_search_fdatasync=$ac_res
-fi
-rm -f core conftest.err conftest.$ac_objext \
-    conftest$ac_exeext
-  if ${ac_cv_search_fdatasync+:} false; then :
-  break
-fi
-done
-if ${ac_cv_search_fdatasync+:} false; then :
-
-else
-  ac_cv_search_fdatasync=no
-fi
-rm conftest.$ac_ext
-LIBS=$ac_func_search_save_LIBS
-fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_search_fdatasync" >&5
-$as_echo "$ac_cv_search_fdatasync" >&6; }
-ac_res=$ac_cv_search_fdatasync
-if test "$ac_res" != no; then :
-  test "$ac_res" = "none required" || LIBS="$ac_res $LIBS"
-
-fi
-
 # Cygwin:
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for library containing shmget" >&5
 $as_echo_n "checking for library containing shmget... " >&6; }
@@ -16039,7 +15982,7 @@ fi
 LIBS_including_readline="$LIBS"
 LIBS=`echo "$LIBS" | sed -e 's/-ledit//g' -e 's/-lreadline//g'`
 
-for ac_func in backtrace_symbols clock_gettime copyfile fdatasync getifaddrs getpeerucred getrlimit inet_pton kqueue mbstowcs_l memset_s poll posix_fallocate ppoll pthread_is_threaded_np readlink readv setproctitle setproctitle_fast setsid shm_open strchrnul strsignal symlink syncfs sync_file_range uselocale wcstombs_l writev
+for ac_func in backtrace_symbols clock_gettime copyfile getifaddrs getpeerucred getrlimit inet_pton kqueue mbstowcs_l memset_s poll posix_fallocate ppoll pthread_is_threaded_np readlink readv setproctitle setproctitle_fast setsid shm_open strchrnul strsignal symlink syncfs sync_file_range uselocale wcstombs_l writev
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
 ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
diff --git a/configure.ac b/configure.ac
index 5295cb5806..0b64b35b39 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1253,8 +1253,6 @@ AC_SEARCH_LIBS(getopt_long, [getopt gnugetopt])
 AC_SEARCH_LIBS(shm_open, rt)
 AC_SEARCH_LIBS(shm_unlink, rt)
 AC_SEARCH_LIBS(clock_gettime, [rt posix4])
-# Solaris:
-AC_SEARCH_LIBS(fdatasync, [rt posix4])
 # Cygwin:
 AC_SEARCH_LIBS(shmget, cygipc)
 # *BSD:
@@ -1796,7 +1794,6 @@ AC_CHECK_FUNCS(m4_normalize([
 	backtrace_symbols
 	clock_gettime
 	copyfile
-	fdatasync
 	getifaddrs
 	getpeerucred
 	getrlimit
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 1da3b8eb2e..fc972873c8 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -168,9 +168,7 @@ const struct config_enum_entry sync_method_options[] = {
 #ifdef HAVE_FSYNC_WRITETHROUGH
 	{"fsync_writethrough", SYNC_METHOD_FSYNC_WRITETHROUGH, false},
 #endif
-#ifdef HAVE_FDATASYNC
 	{"fdatasync", SYNC_METHOD_FDATASYNC, false},
-#endif
 #ifdef O_SYNC
 	{"open_sync", SYNC_METHOD_OPEN, false},
 #endif
@@ -8015,12 +8013,10 @@ issue_xlog_fsync(int fd, XLogSegNo segno, TimeLineID tli)
 				msg = _("could not fsync write-through file \"%s\": %m");
 			break;
 #endif
-#ifdef HAVE_FDATASYNC
 		case SYNC_METHOD_FDATASYNC:
 			if (pg_fdatasync(fd) != 0)
 				msg = _("could not fdatasync file \"%s\": %m");
 			break;
-#endif
 		case SYNC_METHOD_OPEN:
 		case SYNC_METHOD_OPEN_DSYNC:
 			/* not reachable */
diff --git a/src/backend/storage/file/fd.c b/src/backend/storage/file/fd.c
index f904f60c08..c3169d14e6 100644
--- a/src/backend/storage/file/fd.c
+++ b/src/backend/storage/file/fd.c
@@ -442,20 +442,12 @@ pg_fsync_writethrough(int fd)
 
 /*
  * pg_fdatasync --- same as fdatasync except does nothing if enableFsync is off
- *
- * Not all platforms have fdatasync; treat as fsync if not available.
  */
 int
 pg_fdatasync(int fd)
 {
 	if (enableFsync)
-	{
-#ifdef HAVE_FDATASYNC
 		return fdatasync(fd);
-#else
-		return fsync(fd);
-#endif
-	}
 	else
 		return 0;
 }
diff --git a/src/bin/pg_test_fsync/pg_test_fsync.c b/src/bin/pg_test_fsync/pg_test_fsync.c
index 6739214eb8..93785bba0a 100644
--- a/src/bin/pg_test_fsync/pg_test_fsync.c
+++ b/src/bin/pg_test_fsync/pg_test_fsync.c
@@ -331,7 +331,6 @@ test_sync(int writes_per_op)
 	printf(LABEL_FORMAT, "fdatasync");
 	fflush(stdout);
 
-#ifdef HAVE_FDATASYNC
 	if ((tmpfile = open(filename, O_RDWR | PG_BINARY, 0)) == -1)
 		die("could not open output file");
 	START_TIMER;
@@ -347,9 +346,6 @@ test_sync(int writes_per_op)
 	}
 	STOP_TIMER;
 	close(tmpfile);
-#else
-	printf(NA_FORMAT, _("n/a"));
-#endif
 
 /*
  * Test fsync
diff --git a/src/include/access/xlogdefs.h b/src/include/access/xlogdefs.h
index 810cd1fd86..49e581925c 100644
--- a/src/include/access/xlogdefs.h
+++ b/src/include/access/xlogdefs.h
@@ -67,8 +67,7 @@ typedef uint16 RepOriginId;
 /*
  * This chunk of hackery attempts to determine which file sync methods
  * are available on the current platform, and to choose an appropriate
- * default method.  We assume that fsync() is always available, and that
- * configure determined whether fdatasync() is.
+ * default method.
  *
  * Note that we define our own O_DSYNC on Windows, but not O_SYNC.
  */
@@ -76,10 +75,8 @@ typedef uint16 RepOriginId;
 #define DEFAULT_SYNC_METHOD		PLATFORM_DEFAULT_SYNC_METHOD
 #elif defined(O_DSYNC) && (!defined(O_SYNC) || O_DSYNC != O_SYNC)
 #define DEFAULT_SYNC_METHOD		SYNC_METHOD_OPEN_DSYNC
-#elif defined(HAVE_FDATASYNC)
-#define DEFAULT_SYNC_METHOD		SYNC_METHOD_FDATASYNC
 #else
-#define DEFAULT_SYNC_METHOD		SYNC_METHOD_FSYNC
+#define DEFAULT_SYNC_METHOD		SYNC_METHOD_FDATASYNC
 #endif
 
 #endif							/* XLOG_DEFS_H */
diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in
index 86d0b1941b..e72a181a73 100644
--- a/src/include/pg_config.h.in
+++ b/src/include/pg_config.h.in
@@ -188,9 +188,6 @@
 /* Define to 1 if you have the `explicit_bzero' function. */
 #undef HAVE_EXPLICIT_BZERO
 
-/* Define to 1 if you have the `fdatasync' function. */
-#undef HAVE_FDATASYNC
-
 /* Define to 1 if fseeko (and presumably ftello) exists and is declared. */
 #undef HAVE_FSEEKO
 
diff --git a/src/include/port/freebsd.h b/src/include/port/freebsd.h
index 2e2e749a6b..0e3fde55d6 100644
--- a/src/include/port/freebsd.h
+++ b/src/include/port/freebsd.h
@@ -5,6 +5,4 @@
  * would prefer open_datasync on FreeBSD 13+, but that is not a good choice on
  * many systems.
  */
-#ifdef HAVE_FDATASYNC
 #define PLATFORM_DEFAULT_SYNC_METHOD	SYNC_METHOD_FDATASYNC
-#endif
diff --git a/src/include/port/win32_port.h b/src/include/port/win32_port.h
index 4de5bf3bf6..5121c0c626 100644
--- a/src/include/port/win32_port.h
+++ b/src/include/port/win32_port.h
@@ -83,14 +83,6 @@
 #define HAVE_FSYNC_WRITETHROUGH
 #define FSYNC_WRITETHROUGH_IS_FSYNC
 
-/*
- * We have a replacement for fdatasync() in src/port/fdatasync.c, which is
- * unconditionally used by MSVC and Mingw builds.
- */
-#ifndef HAVE_FDATASYNC
-#define HAVE_FDATASYNC
-#endif
-
 #define USES_WINSOCK
 
 /*
diff --git a/src/tools/msvc/Solution.pm b/src/tools/msvc/Solution.pm
index 23296527ae..207cf5b7b0 100644
--- a/src/tools/msvc/Solution.pm
+++ b/src/tools/msvc/Solution.pm
@@ -257,7 +257,6 @@ sub GenerateFiles
 		HAVE_EDITLINE_READLINE_H                    => undef,
 		HAVE_EXECINFO_H                             => undef,
 		HAVE_EXPLICIT_BZERO                         => undef,
-		HAVE_FDATASYNC                              => 1,
 		HAVE_FSEEKO                                 => 1,
 		HAVE_FUNCNAME__FUNC                         => undef,
 		HAVE_FUNCNAME__FUNCTION                     => 1,
-- 
2.36.1