Use unlocked version of changes for GetImage

Fixes #7999

Signed-off-by: Alexandr Morozov <lk4d4math@gmail.com>

daemon/container.go

@@ -686,10 +686,14 @@ func (container *Container) Mount() error {
 	return container.daemon.Mount(container)
 }
 
+func (container *Container) changes() ([]archive.Change, error) {
+	return container.daemon.Changes(container)
+}
+
 func (container *Container) Changes() ([]archive.Change, error) {
 	container.Lock()
 	defer container.Unlock()
-	return container.daemon.Changes(container)
+	return container.changes()
 }
 
 func (container *Container) GetImage() (*image.Image, error) {
@@ -759,7 +763,7 @@ func (container *Container) GetSize() (int64, int64) {
 			sizeRw = -1
 		}
 	} else {
-		changes, _ := container.Changes()
+		changes, _ := container.changes()
 		if changes != nil {
 			sizeRw = archive.ChangesSize(container.basefs, changes)
 		} else {