Use containerd's ErrUnavailable instead of our own error type

Signed-off-by: Kazuyoshi Kato <[email protected]>

Author: kzys

runtime/service.go

@@ -715,9 +715,11 @@ func (s *service) Create(requestCtx context.Context, request *taskAPI.CreateTask
 	for _, mnt := range request.Rootfs {
 		driveID, err = s.stubDriveHandler.PatchStubDrive(requestCtx, s.machine, mnt.Source)
 		if err != nil {
+			if err == ErrDrivesExhausted {
+				return nil, errors.Wrapf(errdefs.ErrUnavailable, "no remaining stub drives to be used")
+			}
 			return nil, errors.Wrapf(err, "failed to patch stub drive")
 		}
-
 	}
 
 	ociConfigBytes, err := bundleDir.OCIConfig().Bytes()

runtime/service_integ_test.go

@@ -725,6 +725,6 @@ func TestCreateTooManyContainers_Isolated(t *testing.T) {
 
 	// When we reuse a VM explicitly, we cannot start multiple containers unless we pre-allocate stub drives.
 	_, err = c2.NewTask(ctx, cio.NewCreator(cio.WithStreams(nil, &stdout, &stderr)))
-	assert.Equal("failed to patch stub drive: There are no remaining drives to be used: unknown", err.Error())
+	assert.Equal("no remaining stub drives to be used: unavailable: unknown", err.Error())
 	require.Error(t, err)
 }