ct: give criu informations about cgroup mounts

Actually cgroup mounts are bind-mounts, so they should be
handled by the same way.

Reported-by: Ross Boucher <rboucher@gmail.com>
Signed-off-by: Andrey Vagin <avagin@openvz.org>

libcontainer/container_linux.go

@@ -293,6 +293,19 @@ func (c *linuxContainer) checkCriuVersion() error {
 
 const descriptors_filename = "descriptors.json"
 
+func (c *linuxContainer) addCriuDumpMount(req *criurpc.CriuReq, m *configs.Mount) {
+	mountDest := m.Destination
+	if strings.HasPrefix(mountDest, c.config.Rootfs) {
+		mountDest = mountDest[len(c.config.Rootfs):]
+	}
+
+	extMnt := &criurpc.ExtMountMap{
+		Key: proto.String(mountDest),
+		Val: proto.String(mountDest),
+	}
+	req.Opts.ExtMnt = append(req.Opts.ExtMnt, extMnt)
+}
+
 func (c *linuxContainer) Checkpoint(criuOpts *CriuOpts) error {
 	c.m.Lock()
 	defer c.m.Unlock()
@@ -356,22 +369,25 @@ func (c *linuxContainer) Checkpoint(criuOpts *CriuOpts) error {
 	}
 
 	t := criurpc.CriuReqType_DUMP
-	req := criurpc.CriuReq{
+	req := &criurpc.CriuReq{
 		Type: &t,
 		Opts: &rpcOpts,
 	}
 
 	for _, m := range c.config.Mounts {
-		if m.Device == "bind" {
+		switch m.Device {
-			mountDest := m.Destination
+		case "bind":
-			if strings.HasPrefix(mountDest, c.config.Rootfs) {
+			c.addCriuDumpMount(req, m)
-				mountDest = mountDest[len(c.config.Rootfs):]
+			break
+		case "cgroup":
+			binds, err := getCgroupMounts(m)
+			if err != nil {
+				return err
 			}
-
+			for _, b := range binds {
-			extMnt := new(criurpc.ExtMountMap)
+				c.addCriuDumpMount(req, b)
-			extMnt.Key = proto.String(mountDest)
+			}
-			extMnt.Val = proto.String(mountDest)
+			break
-			req.Opts.ExtMnt = append(req.Opts.ExtMnt, extMnt)
 		}
 	}
 
@@ -387,13 +403,26 @@ func (c *linuxContainer) Checkpoint(criuOpts *CriuOpts) error {
 		return err
 	}
 
-	err = c.criuSwrk(nil, &req, criuOpts)
+	err = c.criuSwrk(nil, req, criuOpts)
 	if err != nil {
 		return err
 	}
 	return nil
 }
 
+func (c *linuxContainer) addCriuRestoreMount(req *criurpc.CriuReq, m *configs.Mount) {
+	mountDest := m.Destination
+	if strings.HasPrefix(mountDest, c.config.Rootfs) {
+		mountDest = mountDest[len(c.config.Rootfs):]
+	}
+
+	extMnt := &criurpc.ExtMountMap{
+		Key: proto.String(mountDest),
+		Val: proto.String(m.Source),
+	}
+	req.Opts.ExtMnt = append(req.Opts.ExtMnt, extMnt)
+}
+
 func (c *linuxContainer) Restore(process *Process, criuOpts *CriuOpts) error {
 	c.m.Lock()
 	defer c.m.Unlock()
@@ -449,7 +478,7 @@ func (c *linuxContainer) Restore(process *Process, criuOpts *CriuOpts) error {
 	defer syscall.Unmount(root, syscall.MNT_DETACH)
 
 	t := criurpc.CriuReqType_RESTORE
-	req := criurpc.CriuReq{
+	req := &criurpc.CriuReq{
 		Type: &t,
 		Opts: &criurpc.CriuOpts{
 			ImagesDirFd:    proto.Int32(int32(imageDir.Fd())),
@@ -468,16 +497,19 @@ func (c *linuxContainer) Restore(process *Process, criuOpts *CriuOpts) error {
 		},
 	}
 	for _, m := range c.config.Mounts {
-		if m.Device == "bind" {
+		switch m.Device {
-			mountDest := m.Destination
+		case "bind":
-			if strings.HasPrefix(mountDest, c.config.Rootfs) {
+			c.addCriuRestoreMount(req, m)
-				mountDest = mountDest[len(c.config.Rootfs):]
+			break
+		case "cgroup":
+			binds, err := getCgroupMounts(m)
+			if err != nil {
+				return err
 			}
-
+			for _, b := range binds {
-			extMnt := new(criurpc.ExtMountMap)
+				c.addCriuRestoreMount(req, b)
-			extMnt.Key = proto.String(mountDest)
+			}
-			extMnt.Val = proto.String(m.Source)
+			break
-			req.Opts.ExtMnt = append(req.Opts.ExtMnt, extMnt)
 		}
 	}
 	for _, iface := range c.config.Networks {
@@ -515,7 +547,7 @@ func (c *linuxContainer) Restore(process *Process, criuOpts *CriuOpts) error {
 		}
 	}
 
-	err = c.criuSwrk(process, &req, criuOpts)
+	err = c.criuSwrk(process, req, criuOpts)
 	if err != nil {
 		return err
 	}

libcontainer/rootfs_linux.go

@@ -170,27 +170,10 @@ func mountToRootfs(m *configs.Mount, rootfs, mountLabel string) error {
 			}
 		}
 	case "cgroup":
-		mounts, err := cgroups.GetCgroupMounts()
+		binds, err := getCgroupMounts(m)
 		if err != nil {
 			return err
 		}
-		var binds []*configs.Mount
-		for _, mm := range mounts {
-			dir, err := mm.GetThisCgroupDir()
-			if err != nil {
-				return err
-			}
-			relDir, err := filepath.Rel(mm.Root, dir)
-			if err != nil {
-				return err
-			}
-			binds = append(binds, &configs.Mount{
-				Device:      "bind",
-				Source:      filepath.Join(mm.Mountpoint, relDir),
-				Destination: filepath.Join(m.Destination, strings.Join(mm.Subsystems, ",")),
-				Flags:       syscall.MS_BIND | syscall.MS_REC | m.Flags,
-			})
-		}
 		tmpfs := &configs.Mount{
 			Source:      "tmpfs",
 			Device:      "tmpfs",
@@ -211,6 +194,34 @@ func mountToRootfs(m *configs.Mount, rootfs, mountLabel string) error {
 	return nil
 }
 
+func getCgroupMounts(m *configs.Mount) ([]*configs.Mount, error) {
+	mounts, err := cgroups.GetCgroupMounts()
+	if err != nil {
+		return nil, err
+	}
+
+	var binds []*configs.Mount
+
+	for _, mm := range mounts {
+		dir, err := mm.GetThisCgroupDir()
+		if err != nil {
+			return nil, err
+		}
+		relDir, err := filepath.Rel(mm.Root, dir)
+		if err != nil {
+			return nil, err
+		}
+		binds = append(binds, &configs.Mount{
+			Device:      "bind",
+			Source:      filepath.Join(mm.Mountpoint, relDir),
+			Destination: filepath.Join(m.Destination, strings.Join(mm.Subsystems, ",")),
+			Flags:       syscall.MS_BIND | syscall.MS_REC | m.Flags,
+		})
+	}
+
+	return binds, nil
+}
+
 // checkMountDestination checks to ensure that the mount destination is not over the
 // top of /proc or /sys.
 // dest is required to be an abs path and have any symlinks resolved before calling this function.