sync_filesystem: er, fix #define

Signed-off-by: Sage Weil <sage@newdream.net>

diff --git a/src/common/sync_filesystem.h b/src/common/sync_filesystem.h
index 3612dc7d3027bc0a8c9f69e76d948997f95f1749..78afdf13479fa154a51678a64accb10637936bda 100644 (file)
--- a/src/common/sync_filesystem.h
+++ b/src/common/sync_filesystem.h
@@ -15,7 +15,9 @@
 #ifndef CEPH_SYNC_FILESYSTEM_H
 #define CEPH_SYNC_FILESYSTEM_H
 
-#define _GNU_SOURCE
+#ifndef _GNU_SOURCE
+# define _GNU_SOURCE
+#endif
 #include <unistd.h>
 
 inline int sync_filesystem(int fd)