Add fsync to readSyncBulkPayload(). (#7839)

We should sync temp DB file before renaming as rdb_fsync_range does not use
flag `SYNC_FILE_RANGE_WAIT_AFTER`.

Refer to `Linux Programmer's Manual`:
SYNC_FILE_RANGE_WAIT_AFTER
    Wait upon write-out of all pages in the range after performing any write.

(cherry picked from commit 0d62caab2113fc12077aadd469e80dd19ca78db2)

src/replication.c

@@ -1752,6 +1752,17 @@ void readSyncBulkPayload(connection *conn) {
             killRDBChild();
         }
 
+        /* Make sure the new file (also used for persistence) is fully synced
+         * (not covered by earlier calls to rdb_fsync_range). */
+        if (fsync(server.repl_transfer_fd) == -1) {
+            serverLog(LL_WARNING,
+                "Failed trying to sync the temp DB to disk in "
+                "MASTER <-> REPLICA synchronization: %s",
+                strerror(errno));
+            cancelReplicationHandshake();
+            return;
+        }
+
         /* Rename rdb like renaming rewrite aof asynchronously. */
         int old_rdb_fd = open(server.rdb_filename,O_RDONLY|O_NONBLOCK);
         if (rename(server.repl_transfer_tmpfile,server.rdb_filename) == -1) {