Factor mount utility code out gce_pd volume plugin

pkg/util/mount/fake.go

@@ -0,0 +1,34 @@
+/*
+Copyright 2015 Google Inc. All rights reserved.
+
+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 mount
+
+// FakeMounter implements mount.Interface.
+type FakeMounter struct {
+	mountPoints []MountPoint
+}
+
+func (f *FakeMounter) Mount(source string, target string, fstype string, flags uintptr, data string) error {
+	return nil
+}
+
+func (f *FakeMounter) Unmount(target string, flags int) error {
+	return nil
+}
+
+func (f *FakeMounter) List() ([]MountPoint, error) {
+	return f.mountPoints, nil
+}

pkg/util/mount/mount.go

@@ -49,3 +49,30 @@ type MountPoint struct {
 	Freq   int
 	Pass   int
 }
+
+// Examines /proc/mounts to find all other references to the device referenced
+// by mountPath.
+func GetMountRefs(mounter Interface, mountPath string) ([]string, error) {
+	mps, err := mounter.List()
+	if err != nil {
+		return nil, err
+	}
+
+	// Find the device name.
+	deviceName := ""
+	for i := range mps {
+		if mps[i].Path == mountPath {
+			deviceName = mps[i].Device
+			break
+		}
+	}
+
+	// Find all references to the device.
+	var refs []string
+	for i := range mps {
+		if mps[i].Device == deviceName && mps[i].Path != mountPath {
+			refs = append(refs, mps[i].Path)
+		}
+	}
+	return refs, nil
+}

pkg/util/mount/mount_linux_test.go

@@ -91,3 +91,63 @@ func slicesEqual(a, b []string) bool {
 	}
 	return true
 }
+
+func TestGetMountRefs(t *testing.T) {
+	fm := &FakeMounter{
+		[]MountPoint{
+			{Device: "/dev/sdb", Path: "/var/lib/kubelet/plugins/kubernetes.io/gce-pd/mounts/gce-pd"},
+			{Device: "/dev/sdb", Path: "/var/lib/kubelet/pods/some-pod/volumes/kubernetes.io~gce-pd/gce-pd-in-pod"},
+			{Device: "/dev/sdc", Path: "/var/lib/kubelet/plugins/kubernetes.io/gce-pd/mounts/gce-pd2"},
+			{Device: "/dev/sdc", Path: "/var/lib/kubelet/pods/some-pod/volumes/kubernetes.io~gce-pd/gce-pd2-in-pod"},
+			{Device: "/dev/sdc", Path: "/var/lib/kubelet/pods/some-pod/volumes/kubernetes.io~gce-pd/gce-pd2-in-pod2"},
+		},
+	}
+
+	tests := []struct {
+		mountPath    string
+		expectedRefs []string
+	}{
+		{
+			"/var/lib/kubelet/pods/some-pod/volumes/kubernetes.io~gce-pd/gce-pd-in-pod",
+			[]string{
+				"/var/lib/kubelet/plugins/kubernetes.io/gce-pd/mounts/gce-pd",
+			},
+		},
+		{
+			"/var/lib/kubelet/pods/some-pod/volumes/kubernetes.io~gce-pd/gce-pd2-in-pod",
+			[]string{
+				"/var/lib/kubelet/pods/some-pod/volumes/kubernetes.io~gce-pd/gce-pd2-in-pod2",
+				"/var/lib/kubelet/plugins/kubernetes.io/gce-pd/mounts/gce-pd2",
+			},
+		},
+	}
+
+	for i, test := range tests {
+		if refs, err := GetMountRefs(fm, test.mountPath); err != nil || !setEquivalent(test.expectedRefs, refs) {
+			t.Errorf("%d. getMountRefs(%q) = %v, %v; expected %v, nil", i, test.mountPath, refs, err, test.expectedRefs)
+		}
+	}
+}
+
+func setEquivalent(set1, set2 []string) bool {
+	map1 := make(map[string]bool)
+	map2 := make(map[string]bool)
+	for _, s := range set1 {
+		map1[s] = true
+	}
+	for _, s := range set2 {
+		map2[s] = true
+	}
+
+	for s := range map1 {
+		if !map2[s] {
+			return false
+		}
+	}
+	for s := range map2 {
+		if !map1[s] {
+			return false
+		}
+	}
+	return true
+}

pkg/util/mount/mountpoint_unix.go

@@ -0,0 +1,40 @@
+// +build !windows
+
+/*
+Copyright 2014 Google Inc. All rights reserved.
+
+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 mount
+
+import (
+	"os"
+	"syscall"
+)
+
+// Determine if a directory is a mountpoint, by comparing the device for the directory
+// with the device for it's parent.  If they are the same, it's not a mountpoint, if they're
+// different, it is.
+func IsMountPoint(file string) (bool, error) {
+	stat, err := os.Stat(file)
+	if err != nil {
+		return false, err
+	}
+	rootStat, err := os.Lstat(file + "/..")
+	if err != nil {
+		return false, err
+	}
+	// If the directory has the same device as parent, then it's not a mountpoint.
+	return stat.Sys().(*syscall.Stat_t).Dev != rootStat.Sys().(*syscall.Stat_t).Dev, nil
+}

pkg/util/mount/mountpoint_unsupported.go

@@ -0,0 +1,28 @@
+// +build windows
+
+/*
+Copyright 2014 Google Inc. All rights reserved.
+
+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 mount
+
+import (
+	"fmt"
+)
+
+// Dummy implementation for Windows
+func IsMountPoint(file string) (bool, error) {
+	return false, fmt.Errorf("unimplemented")
+}