fixup! Export GenerateID and IDLength from overlay2 graphdriver

daemon/graphdriver/overlay2/overlay.go

@@ -77,13 +77,13 @@ const (
 	lowerFile     = "lower"
 	maxDepth      = 128
 
-	// idLength represents the number of random characters
+	// IDLength represents the number of random characters
 	// which can be used to create the unique link identifier
 	// for every layer. If this value is too long then the
 	// page size limit for the mount command may be exceeded.
-	// The idLength should be selected such that following equation
+	// The IDLength should be selected such that following equation
 	// is true (512 is a buffer for label metadata).
-	// ((idLength + len(linkDir) + 1) * maxDepth) <= (pageSize - 512)
+	// ((IDLength + len(linkDir) + 1) * maxDepth) <= (pageSize - 512)
 	IDLength = 26
 )
 
@@ -371,7 +371,7 @@ func (d *Driver) create(id, parent string, opts *graphdriver.CreateOpts) (retErr
 		return err
 	}
 
-	lid := GenerateID(idLength)
+	lid := GenerateID(IDLength)
 	if err := os.Symlink(path.Join("..", id, diffDirName), path.Join(d.home, linkDir, lid)); err != nil {
 		return err
 	}

daemon/graphdriver/overlay2/randomid.go

@@ -14,7 +14,7 @@ import (
 	"golang.org/x/sys/unix"
 )
 
-// generateID creates a new random string identifier with the given length
+// GenerateID creates a new random string identifier with the given length
 func GenerateID(l int) string {
 	const (
 		// ensures we backoff for less than 450ms total. Use the following to