From 3da84e18447c4618d56296eb2a7473339e34608e Mon Sep 17 00:00:00 2001
From: Brendan Burns <bburns@google.com>
Date: Thu, 11 Dec 2014 16:27:58 -0800
Subject: [PATCH] Fix GCE-PD so that it works even if the PD is already
 attached.

---
 pkg/volume/gce_util.go            | 16 ++++++++-----
 pkg/volume/mount_utils.go         | 40 +++++++++++++++++++++++++++++++
 pkg/volume/mount_utils_windows.go | 28 ++++++++++++++++++++++
 pkg/volume/volume.go              | 20 +++++++++++-----
 4 files changed, 92 insertions(+), 12 deletions(-)
 create mode 100644 pkg/volume/mount_utils.go
 create mode 100644 pkg/volume/mount_utils_windows.go

diff --git a/pkg/volume/gce_util.go b/pkg/volume/gce_util.go
index 781e9b1e34..9682579ad3 100644
--- a/pkg/volume/gce_util.go
+++ b/pkg/volume/gce_util.go
@@ -72,19 +72,23 @@ func (util *GCEDiskUtil) AttachDisk(GCEPD *GCEPersistentDisk) error {
 	}
 	globalPDPath := makeGlobalPDName(GCEPD.RootDir, GCEPD.PDName, GCEPD.ReadOnly)
 	// Only mount the PD globally once.
-	_, err = os.Stat(globalPDPath)
-	if os.IsNotExist(err) {
-		err = os.MkdirAll(globalPDPath, 0750)
-		if err != nil {
+	mountpoint, err := isMountPoint(globalPDPath)
+	if err != nil {
+		if os.IsNotExist(err) {
+			if err := os.MkdirAll(globalPDPath, 0750); err != nil {
+				return err
+			}
+			mountpoint = false
+		} else {
 			return err
 		}
+	}
+	if !mountpoint {
 		err = GCEPD.mounter.Mount(devicePath, globalPDPath, GCEPD.FSType, flags, "")
 		if err != nil {
 			os.RemoveAll(globalPDPath)
 			return err
 		}
-	} else if err != nil {
-		return err
 	}
 	return nil
 }
diff --git a/pkg/volume/mount_utils.go b/pkg/volume/mount_utils.go
new file mode 100644
index 0000000000..3a0cdc587f
--- /dev/null
+++ b/pkg/volume/mount_utils.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 volume
+
+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
+}
diff --git a/pkg/volume/mount_utils_windows.go b/pkg/volume/mount_utils_windows.go
new file mode 100644
index 0000000000..3250b08ee2
--- /dev/null
+++ b/pkg/volume/mount_utils_windows.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 volume
+
+import (
+	"fmt"
+)
+
+// Dummy implementation for Windows
+func isMountPoint(file string) (bool, error) {
+	return false, fmt.Errorf("unimplemented")
+}
diff --git a/pkg/volume/volume.go b/pkg/volume/volume.go
index fcf53870f4..0007a10c47 100644
--- a/pkg/volume/volume.go
+++ b/pkg/volume/volume.go
@@ -235,11 +235,15 @@ func (PD *GCEPersistentDisk) GetPath() string {
 // Attaches the disk and bind mounts to the volume path.
 func (PD *GCEPersistentDisk) SetUp() error {
 	// TODO: handle failed mounts here.
-	if _, err := os.Stat(PD.GetPath()); !os.IsNotExist(err) {
+	mountpoint, err := isMountPoint(PD.GetPath())
+	glog.V(4).Infof("PersistentDisk set up: %s %v %v", PD.GetPath(), mountpoint, err)
+	if err != nil && !os.IsNotExist(err) {
+		return err
+	}
+	if mountpoint {
 		return nil
 	}
-	err := PD.util.AttachDisk(PD)
-	if err != nil {
+	if err := PD.util.AttachDisk(PD); err != nil {
 		return err
 	}
 	flags := uintptr(0)
@@ -265,6 +269,13 @@ func (PD *GCEPersistentDisk) SetUp() error {
 // Unmounts the bind mount, and detaches the disk only if the PD
 // resource was the last reference to that disk on the kubelet.
 func (PD *GCEPersistentDisk) TearDown() error {
+	mountpoint, err := isMountPoint(PD.GetPath())
+	if err != nil {
+		return err
+	}
+	if !mountpoint {
+		return os.RemoveAll(PD.GetPath())
+	}
 	devicePath, refCount, err := PD.mounter.RefCount(PD)
 	if err != nil {
 		return err
@@ -276,9 +287,6 @@ func (PD *GCEPersistentDisk) TearDown() error {
 	if err := os.RemoveAll(PD.GetPath()); err != nil {
 		return err
 	}
-	if err != nil {
-		return err
-	}
 	// If refCount is 1, then all bind mounts have been removed, and the
 	// remaining reference is the global mount. It is safe to detach.
 	if refCount == 1 {