Merge pull request kubernetes#39768 from rkouj/check-path-exists

Automatic merge from submit-queue (batch tested with PRs 39768, 39463)

Check if path exists before performing unmount

This is part 3 of an effort to check if path exists before performing an unmount operation.
[Part 1](kubernetes#38547) and [part 2](kubernetes#39311) involved auditing the different volume plugins and refactoring their `TearDownAt()s` to use the common util function/or create one if absent.

The ideal way to do this change would involve refactoring of the `TearDownAt()s` of these plugins and make a common util function that checks path. (The plugins involved in this PR use someway of unmounting a bind mount and unmounting a global path, there is also refactoring needed to consolidate disk_manager of fc, rbd and iscsi). A non-goal part of this effort can also involve refactoring all the `SetupAt()s`

In the interest of time and considering other higher priority issues that I am caught up with, I am unable to give the time the refactoring needs. Hence I've made the minimum change that would give the desired output.

I am tracking the work pending in this issue: kubernetes#39251

```release-note
NONE
```

Author: Kubernetes Submit Queue

pkg/volume/azure_dd/azure_dd.go

@@ -34,6 +34,7 @@ import (
 	"k8s.io/kubernetes/pkg/util/mount"
 	utilstrings "k8s.io/kubernetes/pkg/util/strings"
 	"k8s.io/kubernetes/pkg/volume"
+	"k8s.io/kubernetes/pkg/volume/util"
 )
 
 // This is the primary entrypoint for volume plugins.
@@ -316,6 +317,13 @@ func (c *azureDiskUnmounter) TearDown() 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 (c *azureDiskUnmounter) TearDownAt(dir string) error {
+	if pathExists, pathErr := util.PathExists(dir); pathErr != nil {
+		return fmt.Errorf("Error checking if path exists: %v", pathErr)
+	} else if !pathExists {
+		glog.Warningf("Warning: Unmount skipped because path does not exist: %v", dir)
+		return nil
+	}
+
 	notMnt, err := c.mounter.IsLikelyNotMountPoint(dir)
 	if err != nil {
 		glog.Errorf("Error checking if mountpoint %s: %v", dir, err)

pkg/volume/cinder/cinder.go

@@ -34,6 +34,7 @@ import (
 	"k8s.io/kubernetes/pkg/util/mount"
 	"k8s.io/kubernetes/pkg/util/strings"
 	"k8s.io/kubernetes/pkg/volume"
+	"k8s.io/kubernetes/pkg/volume/util"
 )
 
 // This is the primary entrypoint for volume plugins.
@@ -386,6 +387,13 @@ func (c *cinderVolumeUnmounter) TearDown() 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 (c *cinderVolumeUnmounter) TearDownAt(dir string) error {
+	if pathExists, pathErr := util.PathExists(dir); pathErr != nil {
+		return fmt.Errorf("Error checking if path exists: %v", pathErr)
+	} else if !pathExists {
+		glog.Warningf("Warning: Unmount skipped because path does not exist: %v", dir)
+		return nil
+	}
+
 	glog.V(5).Infof("Cinder TearDown of %s", dir)
 	notmnt, err := c.mounter.IsLikelyNotMountPoint(dir)
 	if err != nil {

pkg/volume/fc/BUILD

@@ -23,6 +23,7 @@ go_library(
         "//pkg/util/mount:go_default_library",
         "//pkg/util/strings:go_default_library",
         "//pkg/volume:go_default_library",
+        "//pkg/volume/util:go_default_library",
         "//vendor:github.com/golang/glog",
         "//vendor:k8s.io/apimachinery/pkg/types",
     ],

pkg/volume/fc/fc.go

@@ -27,6 +27,7 @@ import (
 	"k8s.io/kubernetes/pkg/util/mount"
 	"k8s.io/kubernetes/pkg/util/strings"
 	"k8s.io/kubernetes/pkg/volume"
+	"k8s.io/kubernetes/pkg/volume/util"
 )
 
 // This is the primary entrypoint for volume plugins.
@@ -222,6 +223,12 @@ func (c *fcDiskUnmounter) TearDown() error {
 }
 
 func (c *fcDiskUnmounter) TearDownAt(dir string) error {
+	if pathExists, pathErr := util.PathExists(dir); pathErr != nil {
+		return fmt.Errorf("Error checking if path exists: %v", pathErr)
+	} else if !pathExists {
+		glog.Warningf("Warning: Unmount skipped because path does not exist: %v", dir)
+		return nil
+	}
 	return diskTearDown(c.manager, *c, dir, c.mounter)
 }
 

pkg/volume/flexvolume/BUILD

@@ -21,6 +21,7 @@ go_library(
         "//pkg/util/mount:go_default_library",
         "//pkg/util/strings:go_default_library",
         "//pkg/volume:go_default_library",
+        "//pkg/volume/util:go_default_library",
         "//vendor:github.com/golang/glog",
         "//vendor:k8s.io/apimachinery/pkg/apis/meta/v1",
         "//vendor:k8s.io/apimachinery/pkg/types",

pkg/volume/flexvolume/flexvolume.go

@@ -32,6 +32,7 @@ import (
 	"k8s.io/kubernetes/pkg/util/mount"
 	utilstrings "k8s.io/kubernetes/pkg/util/strings"
 	"k8s.io/kubernetes/pkg/volume"
+	"k8s.io/kubernetes/pkg/volume/util"
 )
 
 // This is the primary entrypoint for volume plugins.
@@ -371,6 +372,12 @@ func (f *flexVolumeUnmounter) TearDown() error {
 
 // TearDownAt simply deletes everything in the directory.
 func (f *flexVolumeUnmounter) TearDownAt(dir string) error {
+	if pathExists, pathErr := util.PathExists(dir); pathErr != nil {
+		return fmt.Errorf("Error checking if path exists: %v", pathErr)
+	} else if !pathExists {
+		glog.Warningf("Warning: Unmount skipped because path does not exist: %v", dir)
+		return nil
+	}
 
 	notmnt, err := f.mounter.IsLikelyNotMountPoint(dir)
 	if err != nil {

pkg/volume/iscsi/iscsi.go

@@ -230,6 +230,12 @@ func (c *iscsiDiskUnmounter) TearDown() error {
 }
 
 func (c *iscsiDiskUnmounter) TearDownAt(dir string) error {
+	if pathExists, pathErr := ioutil.PathExists(dir); pathErr != nil {
+		return fmt.Errorf("Error checking if path exists: %v", pathErr)
+	} else if !pathExists {
+		glog.Warningf("Warning: Unmount skipped because path does not exist: %v", dir)
+		return nil
+	}
 	return diskTearDown(c.manager, *c, dir, c.mounter)
 }
 

pkg/volume/rbd/rbd.go

@@ -413,6 +413,12 @@ func (c *rbdUnmounter) TearDown() error {
 }
 
 func (c *rbdUnmounter) TearDownAt(dir string) error {
+	if pathExists, pathErr := volutil.PathExists(dir); pathErr != nil {
+		return fmt.Errorf("Error checking if path exists: %v", pathErr)
+	} else if !pathExists {
+		glog.Warningf("Warning: Unmount skipped because path does not exist: %v", dir)
+		return nil
+	}
 	return diskTearDown(c.manager, *c, dir, c.mounter)
 }