Let ImportantFileWriter Use fdatasync

base/files/file_posix.cc

Index: base/files/file_posix.cc
diff --git a/base/files/file_posix.cc b/base/files/file_posix.cc
index 517390f8eacf71135f9e62aff00de4a2d2b7f337..0a3076177569a1a699a9650fa683fb3553ab24a7 100644
--- a/base/files/file_posix.cc
+++ b/base/files/file_posix.cc
@@ -433,6 +433,16 @@ bool File::Flush() {
   return !CallFsync(file_.get());
 }
 
+bool File::FlushData() {
+#if defined(OS_LINUX) || defined(OS_ANDROID)
+  base::ThreadRestrictions::AssertIOAllowed();
+  DCHECK(IsValid());
+  return !HANDLE_EINTR(fdatasync(file_.get()));

[rvargas (doing something else), 2015/03/20 18:56:05]

is fdatasync a Linux-only thing? What's the behavior on BSD?

[hashimoto, 2015/03/20 19:38:57]

fdatasync is a part of POSIX, but it's not mandatory.
According to what I get from casual searching, Mac OS does not implement
fdatasync.

+#else
+  return Flush();
+#endif
+}
+
 bool File::SetTimes(Time last_access_time, Time last_modified_time) {
   base::ThreadRestrictions::AssertIOAllowed();
   DCHECK(IsValid());