From 9f410597dfa062bbd66c4863a31b402de03aa6a6 Mon Sep 17 00:00:00 2001
From: Leo Yuriev <leo@yuriev.ru>
Date: Mon, 4 Mar 2019 13:39:33 +0300
Subject: [PATCH] mdbx: checking only _POSIX_SYNCHRONIZED_IO for fdatasync
 (musl).

---
 src/osal.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/osal.c b/src/osal.c
index be65bf99..f230faff 100644
--- a/src/osal.c
+++ b/src/osal.c
@@ -685,8 +685,7 @@ int mdbx_filesync(mdbx_filehandle_t fd, bool filesize_changed) {
  *
  * For more info about of a corresponding fdatasync() bug
  * see http://www.spinics.net/lists/linux-ext4/msg33714.html */
-#if _POSIX_C_SOURCE >= 199309L || _XOPEN_SOURCE >= 500 ||                      \
-    defined(_POSIX_SYNCHRONIZED_IO)
+#if defined(_POSIX_SYNCHRONIZED_IO) && _POSIX_SYNCHRONIZED_IO > 0
     if (!filesize_changed && fdatasync(fd) == 0)
       return MDBX_SUCCESS;
 #else