Revert "Move layer mount refcounts to mountedLayer"

This reverts commit 563d0711f83952e561a0d7d5c48fef9810b4f010.

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>
Upstream-commit: e91de9fb9d175541acc95834de486d33feef552a
Component: engine

components/engine/layer/layer.go

@@ -49,10 +49,6 @@ var (
 	// to be created which would result in a layer depth
 	// greater than the 125 max.
 	ErrMaxDepthExceeded = errors.New("max depth exceeded")
-
-	// ErrNotSupported is used when the action is not supppoted
-	// on the current platform
-	ErrNotSupported = errors.New("not support on this platform")
 )
 
 // ChainID is the content-addressable ID of a layer.

components/engine/layer/mounted_layer.go

@@ -12,7 +12,6 @@ type mountedLayer struct {
 	mountID    string
 	initID     string
 	parent     *roLayer
-	path       string
 	layerStore *layerStore
 
 	references map[RWLayer]*referencedRWLayer
@@ -132,21 +131,10 @@ func (rl *referencedRWLayer) Mount(mountLabel string) (string, error) {
 		return "", ErrLayerNotRetained
 	}
 
-	if rl.activityCount > 0 {
-		rl.activityCount++
-		return rl.path, nil
-	}
-
-	m, err := rl.mountedLayer.Mount(mountLabel)
-	if err == nil {
-		rl.activityCount++
-		rl.path = m
-	}
-	return m, err
+	rl.activityCount++
+	return rl.mountedLayer.Mount(mountLabel)
 }
 
-// Unmount decrements the activity count and unmounts the underlying layer
-// Callers should only call `Unmount` once per call to `Mount`, even on error.
 func (rl *referencedRWLayer) Unmount() error {
 	rl.activityL.Lock()
 	defer rl.activityL.Unlock()
@@ -157,11 +145,7 @@ func (rl *referencedRWLayer) Unmount() error {
 	if rl.activityCount == -1 {
 		return ErrLayerNotRetained
 	}
-
 	rl.activityCount--
-	if rl.activityCount > 0 {
-		return nil
-	}
 
 	return rl.mountedLayer.Unmount()
 }