add benchmark for fdatasyncSync

benchmark/fs/bench_fdatasyncSync.js

@@ -0,0 +1,42 @@
+'use strict';
+
+const common = require('../common');
+const fs = require('fs');
+const tmpdir = require('../../test/common/tmpdir');
+tmpdir.refresh();
+
+const tmpfile = tmpdir.resolve(`.existing-file-${process.pid}`);
+fs.writeFileSync(tmpfile, 'this-is-for-a-benchmark', 'utf8');
+
+const bench = common.createBenchmark(main, {
+  type: ['existing', 'non-existing'],
+  n: [1e4],
+});
+
+function main({ n, type }) {
+  let fd;
+
+  switch (type) {
+    case 'existing':
+      fd = fs.openSync(tmpfile, 'r', 0o666);
+      break;
+    case 'non-existing':
+      fd = 1 << 30;
+      break;
+    default:
+      new Error('Invalid type');
+  }
+
+  bench.start();
+  for (let i = 0; i < n; i++) {
+    try {
+      fs.fdatasyncSync(fd);
+    } catch {
+      // do nothing
+    }
+  }
+
+  bench.end(n);
+
+  if (type === 'existing') fs.closeSync(fd);
+}