Merge pull request #46458 from jsafrane/mount-prep

Automatic merge from submit-queue (batch tested with PRs 46458, 50934, 50766, 50970, 47698)

Prepare VolumeHost for running mount tools in containers

This is the first part of implementation of kubernetes/enhancements#278 - running mount utilities in containers.

It updates `VolumeHost` interface:

*  `GetMounter()` now requires volume plugin name, as it is going to return different mounter to different volume plugings, because mount utilities for these plugins can be on different places.
* New `GetExec()` method that should volume plugins use to execute any utilities. This new `Exec` interface will execute them on proper place.
* `SafeFormatAndMount` is updated to the new `Exec` interface.

This is just a preparation, `GetExec` right now leads to simple `os.Exec` and mount utilities are executed on the same place as before. Also, the volume plugins will be updated in subsequent PRs (split into separate PRs, some plugins required lot of changes).

```release-note
NONE
```

@kubernetes/sig-storage-pr-reviews 
@rootfs @gnufied

pkg/volume/cinder/attacher.go

@@ -29,7 +29,7 @@ import (
 	"k8s.io/kubernetes/pkg/util/mount"
 	"k8s.io/kubernetes/pkg/volume"
 	volumeutil "k8s.io/kubernetes/pkg/volume/util"
-	"k8s.io/utils/exec"
+	"k8s.io/kubernetes/pkg/volume/util/volumehelper"
 )
 
 type cinderDiskAttacher struct {
@@ -66,7 +66,7 @@ func (plugin *cinderPlugin) NewAttacher() (volume.Attacher, error) {
 }
 
 func (plugin *cinderPlugin) GetDeviceMountRefs(deviceMountPath string) ([]string, error) {
-	mounter := plugin.host.GetMounter()
+	mounter := plugin.host.GetMounter(plugin.GetPluginName())
 	return mount.GetMountRefs(mounter, deviceMountPath)
 }
 
@@ -262,7 +262,7 @@ func (attacher *cinderDiskAttacher) GetDeviceMountPath(
 
 // FIXME: this method can be further pruned.
 func (attacher *cinderDiskAttacher) MountDevice(spec *volume.Spec, devicePath string, deviceMountPath string) error {
-	mounter := attacher.host.GetMounter()
+	mounter := attacher.host.GetMounter(cinderVolumePluginName)
 	notMnt, err := mounter.IsLikelyNotMountPoint(deviceMountPath)
 	if err != nil {
 		if os.IsNotExist(err) {
@@ -285,7 +285,7 @@ func (attacher *cinderDiskAttacher) MountDevice(spec *volume.Spec, devicePath st
 		options = append(options, "ro")
 	}
 	if notMnt {
-		diskMounter := &mount.SafeFormatAndMount{Interface: mounter, Runner: exec.New()}
+		diskMounter := volumehelper.NewSafeFormatAndMountFromHost(cinderVolumePluginName, attacher.host)
 		mountOptions := volume.MountOptionFromSpec(spec, options...)
 		err = diskMounter.FormatAndMount(devicePath, deviceMountPath, volumeSource.FSType, mountOptions)
 		if err != nil {
@@ -309,7 +309,7 @@ func (plugin *cinderPlugin) NewDetacher() (volume.Detacher, error) {
 		return nil, err
 	}
 	return &cinderDiskDetacher{
-		mounter:        plugin.host.GetMounter(),
+		mounter:        plugin.host.GetMounter(plugin.GetPluginName()),
 		cinderProvider: cinder,
 	}, nil
 }

pkg/volume/cinder/cinder.go

@@ -36,7 +36,6 @@ import (
 	"k8s.io/kubernetes/pkg/volume"
 	"k8s.io/kubernetes/pkg/volume/util"
 	"k8s.io/kubernetes/pkg/volume/util/volumehelper"
-	"k8s.io/utils/exec"
 )
 
 // This is the primary entrypoint for volume plugins.
@@ -116,7 +115,7 @@ func (plugin *cinderPlugin) GetAccessModes() []v1.PersistentVolumeAccessMode {
 }
 
 func (plugin *cinderPlugin) NewMounter(spec *volume.Spec, pod *v1.Pod, _ volume.VolumeOptions) (volume.Mounter, error) {
-	return plugin.newMounterInternal(spec, pod.UID, &CinderDiskUtil{}, plugin.host.GetMounter())
+	return plugin.newMounterInternal(spec, pod.UID, &CinderDiskUtil{}, plugin.host.GetMounter(plugin.GetPluginName()))
 }
 
 func (plugin *cinderPlugin) newMounterInternal(spec *volume.Spec, podUID types.UID, manager cdManager, mounter mount.Interface) (volume.Mounter, error) {
@@ -139,11 +138,11 @@ func (plugin *cinderPlugin) newMounterInternal(spec *volume.Spec, podUID types.U
 		},
 		fsType:             fsType,
 		readOnly:           readOnly,
-		blockDeviceMounter: &mount.SafeFormatAndMount{Interface: mounter, Runner: exec.New()}}, nil
+		blockDeviceMounter: volumehelper.NewSafeFormatAndMountFromHost(plugin.GetPluginName(), plugin.host)}, nil
 }
 
 func (plugin *cinderPlugin) NewUnmounter(volName string, podUID types.UID) (volume.Unmounter, error) {
-	return plugin.newUnmounterInternal(volName, podUID, &CinderDiskUtil{}, plugin.host.GetMounter())
+	return plugin.newUnmounterInternal(volName, podUID, &CinderDiskUtil{}, plugin.host.GetMounter(plugin.GetPluginName()))
 }
 
 func (plugin *cinderPlugin) newUnmounterInternal(volName string, podUID types.UID, manager cdManager, mounter mount.Interface) (volume.Unmounter, error) {
@@ -216,7 +215,7 @@ func (plugin *cinderPlugin) getCloudProvider() (CinderProvider, error) {
 }
 
 func (plugin *cinderPlugin) ConstructVolumeSpec(volumeName, mountPath string) (*volume.Spec, error) {
-	mounter := plugin.host.GetMounter()
+	mounter := plugin.host.GetMounter(plugin.GetPluginName())
 	pluginDir := plugin.host.GetPluginDir(plugin.GetPluginName())
 	sourceName, err := mounter.GetDeviceNameFromMount(mountPath, pluginDir)
 	if err != nil {