Fsync directory while persisting AOF manifest, RDB file, and config file (#10737)

The current process to persist files is `write` the data, `fsync` and `rename` the file,
but a underlying problem is that the rename may be lost when a sudden crash like
power outage and the directory hasn't been persisted.

The article [Ensuring data reaches disk](https://lwn.net/Articles/457667/) mentions
a safe way to update file should be:

1. create a new temp file (on the same file system!)
2. write data to the temp file
3. fsync() the temp file
4. rename the temp file to the appropriate name
5. fsync() the containing directory

This commit handles CONFIG REWRITE, AOF manifest, and RDB file (both for persistence,
and the one the replica gets from the master).
It doesn't handle (yet), ACL SAVE and Cluster configs, since these don't yet follow this pattern.

1 files changed, 10 insertions, 0 deletions

diff --git a/src/replication.c b/src/replication.c
index 8a40a8197..b929b0460 100644
--- a/src/replication.c
+++ b/src/replication.c
@@ -2151,6 +2151,16 @@ void readSyncBulkPayload(connection *conn) {
         /* Close old rdb asynchronously. */
         if (old_rdb_fd != -1) bioCreateCloseJob(old_rdb_fd);
 
+        /* Sync the directory to ensure rename is persisted */
+        if (fsyncFileDir(server.rdb_filename) == -1) {
+            serverLog(LL_WARNING,
+                "Failed trying to sync DB directory %s in "
+                "MASTER <-> REPLICA synchronization: %s",
+                server.rdb_filename, strerror(errno));
+            cancelReplicationHandshake(1);
+            return;
+        }
+
         if (rdbLoad(server.rdb_filename,&rsi,RDBFLAGS_REPLICATION) != C_OK) {
             serverLog(LL_WARNING,
                 "Failed trying to load the MASTER synchronization "