Copyright 2020 The Monogon Project Authors.

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.


From b16e57cc52a437465bbd12c24fb05fe5790afe1d Mon Sep 17 00:00:00 2001
From: Lorenz Brun <lorenz@brun.one>
Date: Tue, 17 Mar 2020 21:41:08 +0100
Subject: [PATCH 2/3] Add a native volume metrics implementation

---
 pkg/volume/BUILD                  |   3 +
 pkg/volume/metrics_native.go      | 101 +++++++++++++++++++++++++++++
 pkg/volume/metrics_native_test.go | 102 ++++++++++++++++++++++++++++++
 3 files changed, 206 insertions(+)
 create mode 100644 pkg/volume/metrics_native.go
 create mode 100644 pkg/volume/metrics_native_test.go

diff --git a/pkg/volume/BUILD b/pkg/volume/BUILD
index 720b13406dc..b6e4b7e6d6f 100644
--- a/pkg/volume/BUILD
+++ b/pkg/volume/BUILD
@@ -7,6 +7,7 @@ go_library(
         "metrics_cached.go",
         "metrics_du.go",
         "metrics_errors.go",
+        "metrics_native.go",
         "metrics_nil.go",
         "metrics_statfs.go",
         "noop_expandable_plugin.go",
@@ -35,6 +36,7 @@ go_library(
         "@io_k8s_client_go//tools/cache:go_default_library",
         "@io_k8s_client_go//tools/record:go_default_library",
         "@io_k8s_cloud_provider//:go_default_library",
+        "@org_golang_x_sys//unix:go_default_library",
         "@io_k8s_klog//:go_default_library",
         "@io_k8s_utils//exec:go_default_library",
         "@io_k8s_utils//mount:go_default_library",
@@ -55,6 +57,7 @@ go_test(
     name = "go_default_test",
     srcs = [
         "metrics_du_test.go",
+        "metrics_native_test.go",
         "metrics_nil_test.go",
         "metrics_statfs_test.go",
         "plugins_test.go",
diff --git a/pkg/volume/metrics_native.go b/pkg/volume/metrics_native.go
new file mode 100644
index 00000000000..3934b946f2e
--- /dev/null
+++ b/pkg/volume/metrics_native.go
@@ -0,0 +1,101 @@
+/*
+Copyright 2020 The Kubernetes Authors.
+
+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 volume
+
+import (
+	"os"
+	"path/filepath"
+
+	"golang.org/x/sys/unix"
+	"k8s.io/apimachinery/pkg/api/resource"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+)
+
+var _ MetricsProvider = &metricsNative{}
+
+// MetricsNative represents a MetricsProvider that calculates the volume metrics with either a quota
+// or by walking the path using syscalls.
+type metricsNative struct {
+	path string
+}
+
+// NewMetricsNative returns a new metricsNative provider
+func NewMetricsNative(path string) MetricsProvider {
+	return &metricsNative{path}
+}
+
+// GetMetrics returns an empty Metrics and an error.
+// See MetricsProvider.GetMetrics
+func (m *metricsNative) GetMetrics() (*Metrics, error) {
+	var inodesCount int64
+	var bytesCount int64
+
+	var getMetricsRecursive func(path string) error
+	getMetricsRecursive = func(path string) error {
+		var stat unix.Stat_t
+		err := unix.Lstat(path, &stat)
+		if os.IsNotExist(err) {
+			return nil
+		} else if err != nil {
+			return err
+		}
+		// TODO: This double-counts hardlinks
+		bytesCount += stat.Blocks * 512
+		inodesCount++
+		if stat.Mode&unix.S_IFDIR != 0 && stat.Mode&unix.S_IFLNK == 0 {
+			fd, err := os.Open(path)
+			if os.IsNotExist(err) {
+				return nil
+			} else if err != nil {
+				return err
+			}
+			// We manually close fd before recursing, otherwise we have too many FDs open
+
+			entries, err := fd.Readdirnames(0)
+			if err != nil {
+				fd.Close()
+				return err
+			}
+			fd.Close()
+			for _, entry := range entries {
+				if err := getMetricsRecursive(filepath.Join(path, entry)); err != nil {
+					return err
+				}
+			}
+		}
+		return nil
+	}
+
+	if err := getMetricsRecursive(m.path); err != nil {
+		return &Metrics{}, err
+	}
+
+	var statfs unix.Statfs_t
+	if err := unix.Statfs(m.path, &statfs); err != nil {
+		return &Metrics{}, err
+	}
+
+	return &Metrics{
+		Time:       metav1.Now(),
+		Used:       resource.NewQuantity(bytesCount, resource.BinarySI),
+		InodesUsed: resource.NewQuantity(inodesCount, resource.BinarySI),
+		Available:  resource.NewQuantity(int64(statfs.Bavail)*statfs.Bsize, resource.BinarySI),
+		Capacity:   resource.NewQuantity(int64(statfs.Blocks)*statfs.Bsize, resource.BinarySI),
+		Inodes:     resource.NewQuantity(int64(statfs.Files)*statfs.Bsize, resource.BinarySI),
+		InodesFree: resource.NewQuantity(int64(statfs.Ffree)*statfs.Bsize, resource.BinarySI),
+	}, nil
+}
diff --git a/pkg/volume/metrics_native_test.go b/pkg/volume/metrics_native_test.go
new file mode 100644
index 00000000000..2d5546591ce
--- /dev/null
+++ b/pkg/volume/metrics_native_test.go
@@ -0,0 +1,102 @@
+// +build linux
+
+/*
+Copyright 2015 The Kubernetes Authors.
+
+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 volume_test
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"testing"
+
+	utiltesting "k8s.io/client-go/util/testing"
+	. "k8s.io/kubernetes/pkg/volume"
+	volumetest "k8s.io/kubernetes/pkg/volume/testing"
+)
+
+// TestMetricsNativeGetCapacity tests that MetricsNative can read disk usage
+// for path
+func TestMetricsNativeGetCapacity(t *testing.T) {
+	tmpDir, err := utiltesting.MkTmpdir("metrics_du_test")
+	if err != nil {
+		t.Fatalf("Can't make a tmp dir: %v", err)
+	}
+	defer os.RemoveAll(tmpDir)
+	metrics := NewMetricsNative(tmpDir)
+
+	expectedEmptyDirUsage, err := volumetest.FindEmptyDirectoryUsageOnTmpfs()
+	if err != nil {
+		t.Errorf("Unexpected error finding expected empty directory usage on tmpfs: %v", err)
+	}
+
+	actual, err := metrics.GetMetrics()
+	if err != nil {
+		t.Errorf("Unexpected error when calling GetMetrics %v", err)
+	}
+	if e, a := expectedEmptyDirUsage.Value(), actual.Used.Value(); e != a {
+		t.Errorf("Unexpected value for empty directory; expected %v, got %v", e, a)
+	}
+
+	// TODO(pwittroc): Figure out a way to test these values for correctness, maybe by formatting and mounting a file
+	// as a filesystem
+	if a := actual.Capacity.Value(); a <= 0 {
+		t.Errorf("Expected Capacity %d to be greater than 0.", a)
+	}
+	if a := actual.Available.Value(); a <= 0 {
+		t.Errorf("Expected Available %d to be greater than 0.", a)
+	}
+
+	// Write a file in a directory and expect Used to increase
+	os.MkdirAll(filepath.Join(tmpDir, "d1"), 0755)
+	ioutil.WriteFile(filepath.Join(tmpDir, "d1", "f1"), []byte("Hello World"), os.ModeTemporary)
+	actual, err = metrics.GetMetrics()
+	if err != nil {
+		t.Errorf("Unexpected error when calling GetMetrics %v", err)
+	}
+	if e, a := (2*expectedEmptyDirUsage.Value() + getExpectedBlockSize(filepath.Join(tmpDir, "d1", "f1"))), actual.Used.Value(); e != a {
+		t.Errorf("Unexpected Used for directory with file.  Expected %v, got %d.", e, a)
+	}
+}
+
+// TestMetricsNativeRequireInit tests that if MetricsNative is not initialized with a path, GetMetrics
+// returns an error
+func TestMetricsNativeRequirePath(t *testing.T) {
+	metrics := NewMetricsNative("")
+	actual, err := metrics.GetMetrics()
+	expected := &Metrics{}
+	if !volumetest.MetricsEqualIgnoreTimestamp(actual, expected) {
+		t.Errorf("Expected empty Metrics from uninitialized MetricsNative, actual %v", *actual)
+	}
+	if err == nil {
+		t.Errorf("Expected error when calling GetMetrics on uninitialized MetricsNative, actual nil")
+	}
+}
+
+// TestMetricsNativeRealDirectory tests that if MetricsNative is initialized to a non-existent path, GetMetrics
+// returns an error
+func TestMetricsNativeRequireRealDirectory(t *testing.T) {
+	metrics := NewMetricsNative("/not/a/real/directory")
+	actual, err := metrics.GetMetrics()
+	expected := &Metrics{}
+	if !volumetest.MetricsEqualIgnoreTimestamp(actual, expected) {
+		t.Errorf("Expected empty Metrics from incorrectly initialized MetricsNative, actual %v", *actual)
+	}
+	if err == nil {
+		t.Errorf("Expected error when calling GetMetrics on incorrectly initialized MetricsNative, actual nil")
+	}
+}
-- 
2.25.1