pg_rewind: Move syncTargetDirectory() to file_ops.c

For consistency. All the other low-level functions that operate on the
target directory are in file_ops.c.

Reviewed-by: Michael Paquier
Discussion: https://www.postgresql.org/message-id/0c5b3783-af52-3ee5-f8fa-6e794061f70d%40iki.fi

1 files changed, 19 insertions, 0 deletions

diff --git a/src/bin/pg_rewind/file_ops.c b/src/bin/pg_rewind/file_ops.c
index b3bf091c546..55439db20ba 100644
--- a/src/bin/pg_rewind/file_ops.c
+++ b/src/bin/pg_rewind/file_ops.c
@@ -19,6 +19,7 @@
 #include <unistd.h>
 
 #include "common/file_perm.h"
+#include "common/file_utils.h"
 #include "file_ops.h"
 #include "filemap.h"
 #include "pg_rewind.h"
@@ -266,6 +267,24 @@ remove_target_symlink(const char *path)
 				 dstpath);
 }
 
+/*
+ * Sync target data directory to ensure that modifications are safely on disk.
+ *
+ * We do this once, for the whole data directory, for performance reasons.  At
+ * the end of pg_rewind's run, the kernel is likely to already have flushed
+ * most dirty buffers to disk.  Additionally fsync_pgdata uses a two-pass
+ * approach (only initiating writeback in the first pass), which often reduces
+ * the overall amount of IO noticeably.
+ */
+void
+sync_target_dir(void)
+{
+	if (!do_sync || dry_run)
+		return;
+
+	fsync_pgdata(datadir_target, PG_VERSION_NUM);
+}
+
 
 /*
  * Read a file into memory. The file to be read is <datadir>/<path>.