cmd/convertor: support --fstype=erofs for TurboOCI format

Similiar to EXT4 which uses "ext4.fs.meta", add EROFS metadata
"erofs.fs.meta" support too.  Multiple metadata could exist in
each TurboOCI layer, but let's make single fs metadata work first.

To build a EROFS TurboOCI image,
$ bin/convertor --fstype erofs -r <repo> -i <input-tag> --turboOCI <turboOCI-tag>

If `--fstype` is not given, ext4 is used by default.

Signed-off-by: Gao Xiang <[email protected]>

cmd/convertor/builder/builder.go

@@ -54,6 +54,7 @@ type BuilderOptions struct {
 	PlainHTTP bool
 	WorkDir   string
 	OCI       bool
+	FsType    string
 	Mkfs      bool
 	Vsize     int
 	DB        database.ConversionDatabase
@@ -234,6 +235,7 @@ func (b *graphBuilder) buildOne(ctx context.Context, src v1.Descriptor, tag bool
 	}
 	engineBase.workDir = workdir
 	engineBase.oci = b.OCI
+	engineBase.fstype = b.FsType
 	engineBase.mkfs = b.Mkfs
 	engineBase.vsize = b.Vsize
 	engineBase.db = b.DB

cmd/convertor/builder/builder_engine.go

@@ -85,6 +85,7 @@ type builderEngineBase struct {
 	config       specs.Image
 	workDir      string
 	oci          bool
+	fstype       string
 	mkfs         bool
 	vsize        int
 	db           database.ConversionDatabase

cmd/convertor/builder/turboOCI_builder.go

@@ -41,7 +41,7 @@ const (
 	gzipMetaFile = "gzip.meta"
 
 	// index of block device
-	fsMetaFile = "ext4.fs.meta"
+	fsMetaFileSuffix = ".fs.meta"
 
 	// foci index layer (gzip)
 	tociLayerTar = "turboOCIv1.tar.gz"
@@ -103,12 +103,21 @@ func (e *turboOCIBuilderEngine) BuildLayer(ctx context.Context, idx int) error {
 	if err := e.apply(ctx, layerDir); err != nil {
 		return err
 	}
-	if err := e.commit(ctx, layerDir); err != nil {
+
+	var fsMetaFile string
+	if e.fstype == "" {
+		fsMetaFile = "ext4" + fsMetaFileSuffix
+	} else {
+		fsMetaFile = e.fstype + fsMetaFileSuffix
+	}
+
+	if err := e.commit(ctx, layerDir, fsMetaFile); err != nil {
 		return err
 	}
 	if err := e.createIdentifier(idx); err != nil {
 		return errors.Wrapf(err, "failed to create identifier %q", tociIdentifier)
 	}
+
 	files := []string{
 		path.Join(layerDir, fsMetaFile),
 		path.Join(layerDir, tociIdentifier),
@@ -249,18 +258,22 @@ func (e *turboOCIBuilderEngine) create(ctx context.Context, dir string, mkfs boo
 		vsizeGB = e.vsize
 	}
 	opts := []string{"-s", fmt.Sprintf("%d", vsizeGB), "--turboOCI"}
-	if mkfs {
+	if mkfs && e.fstype != "erofs" {
 		opts = append(opts, "--mkfs")
 		logrus.Infof("mkfs for baselayer, vsize: %d GB", vsizeGB)
 	}
 	return utils.Create(ctx, dir, opts...)
 }
 
 func (e *turboOCIBuilderEngine) apply(ctx context.Context, dir string) error {
+	if e.fstype != "" {
+		opts := []string{"--fstype", e.fstype}
+		return utils.ApplyTurboOCI(ctx, dir, gzipMetaFile, opts...)
+	}
 	return utils.ApplyTurboOCI(ctx, dir, gzipMetaFile)
 }
 
-func (e *turboOCIBuilderEngine) commit(ctx context.Context, dir string) error {
+func (e *turboOCIBuilderEngine) commit(ctx context.Context, dir string, fsMetaFile string) error {
 	if err := utils.Commit(ctx, dir, dir, false, "-z", "--fastoci"); err != nil {
 		return err
 	}

cmd/convertor/main.go

@@ -39,6 +39,7 @@ var (
 	tagOutput        string
 	dir              string
 	oci              bool
+	fsType           string
 	mkfs             bool
 	verbose          bool
 	vsize            int
@@ -93,6 +94,7 @@ Version: ` + commitID,
 				PlainHTTP: plain,
 				WorkDir:   dir,
 				OCI:       oci,
+				FsType:    fsType,
 				Mkfs:      mkfs,
 				Vsize:     vsize,
 				CertOption: builder.CertOption{
@@ -159,6 +161,7 @@ func init() {
 	rootCmd.Flags().StringVarP(&tagOutput, "output-tag", "o", "", "tag for image converting to")
 	rootCmd.Flags().StringVarP(&dir, "dir", "d", "tmp_conv", "directory used for temporary data")
 	rootCmd.Flags().BoolVarP(&oci, "oci", "", false, "export image with oci spec")
+	rootCmd.Flags().StringVar(&fsType, "fstype", "ext4", "filesystem type of converted image. Default ext4")
 	rootCmd.Flags().BoolVarP(&mkfs, "mkfs", "", true, "make ext4 fs in bottom layer")
 	rootCmd.Flags().IntVarP(&vsize, "vsize", "", 64, "virtual block device size (GB)")
 	rootCmd.Flags().StringVar(&fastoci, "fastoci", "", "build 'Overlaybd-Turbo OCIv1' format (old name of turboOCIv1. deprecated)")

pkg/snapshot/overlay.go

@@ -574,8 +574,12 @@ func (o *snapshotter) createMountPoint(ctx context.Context, kind snapshots.Kind,
 			}
 			fsType, ok := obdInfo.Labels[label.OverlayBDBlobFsType]
 			if !ok {
-				log.G(ctx).Warnf("cannot get fs type from label, %v, using %s", obdInfo.Labels, o.defaultFsType)
-				fsType = o.defaultFsType
+				if isTurboOCI, _, _ := o.checkTurboOCI(obdInfo.Labels); isTurboOCI {
+					_, fsType = o.turboOCIFsMeta(obdID)
+				} else {
+					fsType = o.defaultFsType
+				}
+				log.G(ctx).Warnf("cannot get fs type from label, %v, using %s", obdInfo.Labels, fsType)
 			}
 			log.G(ctx).Debugf("attachAndMountBlockDevice (obdID: %s, writeType: %s, fsType %s, targetPath: %s)",
 				obdID, writeType, fsType, o.overlaybdTargetPath(obdID))
@@ -733,7 +737,11 @@ func (o *snapshotter) Mounts(ctx context.Context, key string) (_ []mount.Mount,
 		if parentStype == storageTypeRemoteBlock || parentStype == storageTypeLocalBlock {
 			fsType, ok := parentInfo.Labels[label.OverlayBDBlobFsType]
 			if !ok {
-				fsType = o.defaultFsType
+				if isTurboOCI, _, _ := o.checkTurboOCI(parentInfo.Labels); isTurboOCI {
+					_, fsType = o.turboOCIFsMeta(parentID)
+				} else {
+					fsType = o.defaultFsType
+				}
 			}
 			if err := o.attachAndMountBlockDevice(ctx, parentID, RoDir, fsType, false); err != nil {
 				return nil, errors.Wrapf(err, "failed to attach and mount for snapshot %v", key)
@@ -1355,8 +1363,13 @@ func (o *snapshotter) blockPath(id string) string {
 	return filepath.Join(o.root, "snapshots", id, "block")
 }
 
-func (o *snapshotter) turboOCIFsMeta(id string) string {
-	return filepath.Join(o.root, "snapshots", id, "fs", "ext4.fs.meta")
+func (o *snapshotter) turboOCIFsMeta(id string) (string, string) {
+	// TODO: make the priority order (multi-meta exists) configurable later if needed
+	erofsmeta := filepath.Join(o.root, "snapshots", id, "fs", "erofs.fs.meta")
+	if _, err := os.Stat(erofsmeta); err == nil {
+		return erofsmeta, "erofs"
+	}
+	return filepath.Join(o.root, "snapshots", id, "fs", "ext4.fs.meta"), "ext4"
 }
 
 func (o *snapshotter) magicFilePath(id string) string {

pkg/snapshot/storage.go

@@ -502,10 +502,11 @@ func (o *snapshotter) constructOverlayBDSpec(ctx context.Context, key string, wr
 
 		configJSON.RepoBlobURL = blobPrefixURL
 		if isTurboOCI, dataDgst, compType := o.checkTurboOCI(info.Labels); isTurboOCI {
+			fsmeta, _ := o.turboOCIFsMeta(id)
 			lower := sn.OverlayBDBSConfigLower{
 				Dir: o.upperPath(id),
 				// keep this to support ondemand turboOCI loading.
-				File:         o.turboOCIFsMeta(id),
+				File:         fsmeta,
 				TargetDigest: dataDgst,
 			}
 			if isGzipLayerType(compType) {

pkg/utils/cmd.go

@@ -160,7 +160,7 @@ func ApplyTurboOCI(ctx context.Context, dir, gzipMetaFile string, opts ...string
 		path.Join(dir, "config.json"),
 		"--gz_index_path", path.Join(dir, gzipMetaFile)}, opts...)
 	log.G(ctx).Debugf("%s %s", obdBinApply, strings.Join(args, " "))
-	out, err := exec.CommandContext(ctx, obdBinApply, args...).CombinedOutput()
+	out, err := exec.CommandContext(ctx, obdBinTurboOCIApply, args...).CombinedOutput()
 	if err != nil {
 		return errors.Wrapf(err, "failed to overlaybd-apply[turboOCI]: %s", out)
 	}