Add a boolean return form unmount to indicate when the layer is reall…

…y unmounted

Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>

cmd/containers-storage/mount.go

@@ -51,7 +51,7 @@ func unmount(flags *mflag.FlagSet, action string, m storage.Store, args []string
 	mes := []mountPointError{}
 	errors := false
 	for _, arg := range args {
-		err := m.Unmount(arg, false)
+		_, err := m.Unmount(arg, false)
 		errText := ""
 		if err != nil {
 			errText = fmt.Sprintf("%v", err)

layers.go

@@ -211,7 +211,7 @@ type LayerStore interface {
 	Mount(id, mountLabel string) (string, error)
 
 	// Unmount unmounts a layer when it is no longer in use.
-	Unmount(id string, force bool) error
+	Unmount(id string, force bool) (bool, error)
 
 	// Mounted returns whether or not the layer is mounted
 	Mounted(id string) (bool, error)
@@ -663,15 +663,15 @@ func (r *layerStore) Mount(id, mountLabel string) (string, error) {
 	return mountpoint, err
 }
 
-func (r *layerStore) Unmount(id string, force bool) error {
+func (r *layerStore) Unmount(id string, force bool) (bool, error) {
 	if !r.IsReadWrite() {
-		return errors.Wrapf(ErrStoreIsReadOnly, "not allowed to update mount locations for layers at %q", r.mountspath())
+		return false, errors.Wrapf(ErrStoreIsReadOnly, "not allowed to update mount locations for layers at %q", r.mountspath())
 	}
 	layer, ok := r.lookup(id)
 	if !ok {
 		layerByMount, ok := r.bymount[filepath.Clean(id)]
 		if !ok {
-			return ErrLayerUnknown
+			return false, ErrLayerUnknown
 		}
 		layer = layerByMount
 	}
@@ -680,7 +680,7 @@ func (r *layerStore) Unmount(id string, force bool) error {
 	}
 	if layer.MountCount > 1 {
 		layer.MountCount--
-		return r.Save()
+		return true, r.Save()
 	}
 	err := r.driver.Put(id)
 	if err == nil || os.IsNotExist(err) {
@@ -691,7 +691,7 @@ func (r *layerStore) Unmount(id string, force bool) error {
 		layer.MountPoint = ""
 		err = r.Save()
 	}
-	return err
+	return false, err
 }
 
 func (r *layerStore) ParentOwners(id string) (uids, gids []int, err error) {
@@ -811,7 +811,7 @@ func (r *layerStore) Delete(id string) error {
 		return ErrLayerUnknown
 	}
 	id = layer.ID
-	if err := r.Unmount(id, true); err != nil {
+	if _, err := r.Unmount(id, true); err != nil {
 		return err
 	}
 	err := r.driver.Remove(id)
@@ -929,7 +929,8 @@ func (s *simpleGetCloser) Get(path string) (io.ReadCloser, error) {
 }
 
 func (s *simpleGetCloser) Close() error {
-	return s.r.Unmount(s.id, false)
+	_, err := s.r.Unmount(s.id, false)
+	return err
 }
 
 func (r *layerStore) newFileGetter(id string) (drivers.FileGetCloser, error) {

store.go

@@ -262,8 +262,8 @@ type Store interface {
 	Mount(id, mountLabel string) (string, error)
 
 	// Unmount attempts to unmount a layer, image, or container, given an ID, a
-	// name, or a mount path.
-	Unmount(id string, force bool) error
+	// name, or a mount path. Returns whether or not the layer is still mounted
+	Unmount(id string, force bool) (bool, error)
 
 	// Changes returns a summary of the changes which would need to be made
 	// to one layer to make its contents the same as a second layer.  If
@@ -2262,13 +2262,13 @@ func (s *store) Mounted(id string) (bool, error) {
 	return rlstore.Mounted(id)
 }
 
-func (s *store) Unmount(id string, force bool) error {
+func (s *store) Unmount(id string, force bool) (bool, error) {
 	if layerID, err := s.ContainerLayerID(id); err == nil {
 		id = layerID
 	}
 	rlstore, err := s.LayerStore()
 	if err != nil {
-		return err
+		return false, err
 	}
 	rlstore.Lock()
 	defer rlstore.Unlock()
@@ -2278,7 +2278,7 @@ func (s *store) Unmount(id string, force bool) error {
 	if rlstore.Exists(id) {
 		return rlstore.Unmount(id, force)
 	}
-	return ErrLayerUnknown
+	return false, ErrLayerUnknown
 }
 
 func (s *store) Changes(from, to string) ([]archive.Change, error) {
@@ -2828,7 +2828,7 @@ func (s *store) Shutdown(force bool) ([]string, error) {
 		mounted = append(mounted, layer.ID)
 		if force {
 			for layer.MountCount > 0 {
-				err2 := rlstore.Unmount(layer.ID, force)
+				_, err2 := rlstore.Unmount(layer.ID, force)
 				if err2 != nil {
 					if err == nil {
 						err = err2