Implement the stats for the image_fs_info command

Signed-off-by: Bo Zhao <bzhao@lyft.com>

server/image_fs_info.go

@@ -1,13 +1,42 @@
 package server
 
 import (
-	"fmt"
+	"path"
 	"time"
 
+	"github.com/containers/storage"
+	crioStorage "github.com/kubernetes-incubator/cri-o/utils"
 	"golang.org/x/net/context"
 	pb "k8s.io/kubernetes/pkg/kubelet/apis/cri/v1alpha1/runtime"
 )
 
+func getStorageFsInfo(store storage.Store) (*pb.FilesystemUsage, error) {
+	rootPath := store.GraphRoot()
+	storageDriver := store.GraphDriverName()
+	imagesPath := path.Join(rootPath, storageDriver+"-images")
+
+	deviceName, err := crioStorage.GetDeviceNameFromPath(imagesPath)
+
+	uuid, err := crioStorage.GetDeviceUUIDFromPath(deviceName)
+	if err != nil {
+		return nil, err
+	}
+
+	bytesUsed, inodesUsed, err := crioStorage.GetDiskUsageStats(imagesPath)
+	if err != nil {
+		return nil, err
+	}
+
+	usage := pb.FilesystemUsage{
+		Timestamp:  time.Now().UnixNano(),
+		StorageId:  &pb.StorageIdentifier{uuid},
+		UsedBytes:  &pb.UInt64Value{bytesUsed},
+		InodesUsed: &pb.UInt64Value{inodesUsed},
+	}
+
+	return &usage, nil
+}
+
 // ImageFsInfo returns information of the filesystem that is used to store images.
 func (s *Server) ImageFsInfo(ctx context.Context, req *pb.ImageFsInfoRequest) (resp *pb.ImageFsInfoResponse, err error) {
 	const operation = "image_fs_info"
@@ -16,5 +45,14 @@ func (s *Server) ImageFsInfo(ctx context.Context, req *pb.ImageFsInfoRequest) (r
 		recordError(operation, err)
 	}()
 
-	return nil, fmt.Errorf("not implemented")
+	store := s.StorageImageServer().GetStore()
+	fsUsage, err := getStorageFsInfo(store)
+
+	if err != nil {
+		return nil, err
+	}
+
+	return &pb.ImageFsInfoResponse{
+		ImageFilesystems: []*pb.FilesystemUsage{fsUsage},
+	}, nil
 }