From cf0adcc817e422e86966a24a1dc758369f3c076f Mon Sep 17 00:00:00 2001
From: Vishnu Kannan <vishnuk@google.com>
Date: Fri, 13 Nov 2015 14:19:24 -0800
Subject: [PATCH] Add support for Overlayfs.

Signed-off-by: Vishnu kannan <vishnuk@google.com>
---
 container/docker/factory.go |  5 ++++-
 container/docker/handler.go | 30 ++++++++++++++++++++++--------
 fs/fs.go                    |  2 +-
 3 files changed, 27 insertions(+), 10 deletions(-)

diff --git a/container/docker/factory.go b/container/docker/factory.go
index 4cc22c77..69c981fa 100644
--- a/container/docker/factory.go
+++ b/container/docker/factory.go
@@ -88,7 +88,10 @@ func RootDir() string {
 type storageDriver string
 
 const (
-	aufsStorageDriver storageDriver = "aufs"
+	// TODO: Add support for devicemapper storage usage.
+	devicemapperStorageDriver storageDriver = "devicemapper"
+	aufsStorageDriver         storageDriver = "aufs"
+	overlayStorageDriver      storageDriver = "overlay"
 )
 
 type dockerFactory struct {
diff --git a/container/docker/handler.go b/container/docker/handler.go
index 3440a48a..13318a60 100644
--- a/container/docker/handler.go
+++ b/container/docker/handler.go
@@ -34,12 +34,15 @@ import (
 	libcontainerconfigs "github.com/opencontainers/runc/libcontainer/configs"
 )
 
-// Path to aufs dir where all the files exist.
-// aufs/layers is ignored here since it does not hold a lot of data.
-// aufs/mnt contains the mount points used to compose the rootfs. Hence it is also ignored.
 const (
-	pathToAufsDir       = "aufs/diff"
+	// Path to aufs dir where all the files exist.
+	// aufs/layers is ignored here since it does not hold a lot of data.
+	// aufs/mnt contains the mount points used to compose the rootfs. Hence it is also ignored.
+	pathToAufsDir = "aufs/diff"
+	// Path to the directory where docker stores log files if the json logging driver is enabled.
 	pathToContainersDir = "containers"
+	// Path to the overlayfs storage driver directory.
+	pathToOverlayDir = "overlay"
 )
 
 type dockerContainerHandler struct {
@@ -119,6 +122,8 @@ func newDockerContainerHandler(
 	case aufsStorageDriver:
 		// Add writable layer for aufs.
 		storageDirs = append(storageDirs, path.Join(*dockerRootDir, pathToAufsDir, id))
+	case overlayStorageDriver:
+		storageDirs = append(storageDirs, path.Join(*dockerRootDir, pathToOverlayDir, id))
 	}
 
 	handler := &dockerContainerHandler{
@@ -228,8 +233,14 @@ func (self *dockerContainerHandler) GetSpec() (info.ContainerSpec, error) {
 
 	spec := libcontainerConfigToContainerSpec(libcontainerConfig, mi)
 	spec.CreationTime = self.creationTime
-	// For now only enable for aufs filesystems
-	spec.HasFilesystem = self.storageDriver == aufsStorageDriver
+
+	spec.HasFilesystem = false
+	switch self.storageDriver {
+	case aufsStorageDriver:
+	case overlayStorageDriver:
+		spec.HasFilesystem = true
+	}
+
 	spec.Labels = self.labels
 	spec.Image = self.image
 	spec.HasNetwork = hasNet(self.networkMode)
@@ -238,8 +249,11 @@ func (self *dockerContainerHandler) GetSpec() (info.ContainerSpec, error) {
 }
 
 func (self *dockerContainerHandler) getFsStats(stats *info.ContainerStats) error {
-	// No support for non-aufs storage drivers.
-	if self.storageDriver != aufsStorageDriver {
+	switch self.storageDriver {
+	case aufsStorageDriver:
+	case overlayStorageDriver:
+		break
+	default:
 		return nil
 	}
 
diff --git a/fs/fs.go b/fs/fs.go
index b7913cdd..af21a6e1 100644
--- a/fs/fs.go
+++ b/fs/fs.go
@@ -128,7 +128,7 @@ func getDockerImagePaths(context Context) []string {
 	// TODO(rjnagal): Detect docker root and graphdriver directories from docker info.
 	dockerRoot := context.DockerRoot
 	dockerImagePaths := []string{}
-	for _, dir := range []string{"devicemapper", "btrfs", "aufs"} {
+	for _, dir := range []string{"devicemapper", "btrfs", "aufs", "overlay"} {
 		dockerImagePaths = append(dockerImagePaths, path.Join(dockerRoot, dir))
 	}
 	for dockerRoot != "/" && dockerRoot != "." {