[feat]: use DSYNC for xl.meta writes and NOATIME for reads (#11615)

Instead of using O_SYNC, we are better off using O_DSYNC
instead since we are only ever interested in data to be
persisted to disk not the associated filesystem metadata.

For reads we ask customers to turn off noatime, but instead
we can proactively use O_NOATIME flag to avoid atime updates
upon reads.

cmd/xl-storage_noatime_supported.go

@@ -0,0 +1,31 @@
+// +build !windows,!darwin
+
+/*
+ * MinIO Cloud Storage, (C) 2021 MinIO, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package cmd
+
+import (
+	"os"
+)
+
+var (
+	// Disallow updating access times
+	readMode = os.O_RDONLY | 0x40000 // O_NOATIME
+
+	// Write with data sync only used only for `xl.meta` writes
+	writeMode = 0x1000 // O_DSYNC
+)