From 72b7d16505ae499b554b1f6969f58edb6ce8f170 Mon Sep 17 00:00:00 2001
From: Wei Fu <fuweid89@gmail.com>
Date: Thu, 15 Jun 2023 06:04:19 +0000
Subject: [PATCH 1/5] mount: support direct-io for loopback device

Signed-off-by: Wei Fu <fuweid89@gmail.com>
---
 mount/losetup_linux.go | 27 +++++++++++++--------------
 mount/mount_linux.go   | 38 ++++++++++++++++++++++++++++----------
 2 files changed, 41 insertions(+), 24 deletions(-)

diff --git a/mount/losetup_linux.go b/mount/losetup_linux.go
index 567ebb4e9..e3647e954 100644
--- a/mount/losetup_linux.go
+++ b/mount/losetup_linux.go
@@ -89,6 +89,12 @@ func setupLoopDev(backingFile, loopDev string, param LoopParams) (_ *os.File, re
 		return nil, fmt.Errorf("could not set loop fd for device: %s: %w", loopDev, err)
 	}
 
+	defer func() {
+		if retErr != nil {
+			_ = unix.IoctlSetInt(int(loop.Fd()), unix.LOOP_CLR_FD, 0)
+		}
+	}()
+
 	// 3. Set Info
 	info := unix.LoopInfo64{}
 	copy(info.File_name[:], backingFile)
@@ -100,27 +106,20 @@ func setupLoopDev(backingFile, loopDev string, param LoopParams) (_ *os.File, re
 		info.Flags |= unix.LO_FLAGS_AUTOCLEAR
 	}
 
-	if param.Direct {
-		info.Flags |= unix.LO_FLAGS_DIRECT_IO
-	}
-
 	err = unix.IoctlLoopSetStatus64(int(loop.Fd()), &info)
-	if err == nil {
-		return loop, nil
+	if err != nil {
+		return nil, fmt.Errorf("failed to set loop device info: %w", err)
 	}
 
+	// 4. Set Direct IO
 	if param.Direct {
-		// Retry w/o direct IO flag in case kernel does not support it. The downside is that
-		// it will suffer from double cache problem.
-		info.Flags &= ^(uint32(unix.LO_FLAGS_DIRECT_IO))
-		err = unix.IoctlLoopSetStatus64(int(loop.Fd()), &info)
-		if err == nil {
-			return loop, nil
+		err = unix.IoctlSetInt(int(loop.Fd()), unix.LOOP_SET_DIRECT_IO, 1)
+		if err != nil {
+			return nil, fmt.Errorf("failed to setup loop with direct: %w", err)
 		}
 	}
 
-	_ = unix.IoctlSetInt(int(loop.Fd()), unix.LOOP_CLR_FD, 0)
-	return nil, fmt.Errorf("failed to set loop device info: %v", err)
+	return loop, nil
 }
 
 // setupLoop looks for (and possibly creates) a free loop device, and
diff --git a/mount/mount_linux.go b/mount/mount_linux.go
index 736bb4cbb..adb59b819 100644
--- a/mount/mount_linux.go
+++ b/mount/mount_linux.go
@@ -63,9 +63,6 @@ func (m *Mount) mount(target string) (err error) {
 	}
 
 	flags, data, losetup := parseMountOptions(options)
-	if len(data) > pagesize {
-		return errors.New("mount options is too long")
-	}
 
 	// propagation types.
 	const ptypes = unix.MS_SHARED | unix.MS_PRIVATE | unix.MS_SLAVE | unix.MS_UNBINDABLE
@@ -73,15 +70,27 @@ func (m *Mount) mount(target string) (err error) {
 	// Ensure propagation type change flags aren't included in other calls.
 	oflags := flags &^ ptypes
 
+	var loopParams LoopParams
+	if losetup {
+		loopParams = LoopParams{
+			Readonly:  oflags&unix.MS_RDONLY == unix.MS_RDONLY,
+			Autoclear: true,
+		}
+		loopParams.Direct, data = hasDirectIO(data)
+	}
+
+	dataInStr := strings.Join(data, ",")
+	if len(dataInStr) > pagesize {
+		return errors.New("mount options is too long")
+	}
+
 	// In the case of remounting with changed data (data != ""), need to call mount (moby/moby#34077).
-	if flags&unix.MS_REMOUNT == 0 || data != "" {
+	if flags&unix.MS_REMOUNT == 0 || dataInStr != "" {
 		// Initial call applying all non-propagation flags for mount
 		// or remount with changed data
 		source := m.Source
 		if losetup {
-			loFile, err := setupLoop(m.Source, LoopParams{
-				Readonly:  oflags&unix.MS_RDONLY == unix.MS_RDONLY,
-				Autoclear: true})
+			loFile, err := setupLoop(m.Source, loopParams)
 			if err != nil {
 				return err
 			}
@@ -90,7 +99,7 @@ func (m *Mount) mount(target string) (err error) {
 			// Mount the loop device instead
 			source = loFile.Name()
 		}
-		if err := mountAt(chdir, source, target, m.Type, uintptr(oflags), data); err != nil {
+		if err := mountAt(chdir, source, target, m.Type, uintptr(oflags), dataInStr); err != nil {
 			return err
 		}
 	}
@@ -199,7 +208,7 @@ func UnmountAll(mount string, flags int) error {
 
 // parseMountOptions takes fstab style mount options and parses them for
 // use with a standard mount() syscall
-func parseMountOptions(options []string) (int, string, bool) {
+func parseMountOptions(options []string) (int, []string, bool) {
 	var (
 		flag    int
 		losetup bool
@@ -252,7 +261,16 @@ func parseMountOptions(options []string) (int, string, bool) {
 			data = append(data, o)
 		}
 	}
-	return flag, strings.Join(data, ","), losetup
+	return flag, data, losetup
+}
+
+func hasDirectIO(opts []string) (bool, []string) {
+	for idx, opt := range opts {
+		if opt == "direct-io" {
+			return true, append(opts[:idx], opts[idx+1:]...)
+		}
+	}
+	return false, opts
 }
 
 // compactLowerdirOption updates overlay lowdir option and returns the common

From 6dfb16f99a3bbafb31a93752c61461c77f23db9d Mon Sep 17 00:00:00 2001
From: Wei Fu <fuweid89@gmail.com>
Date: Thu, 15 Jun 2023 06:12:22 +0000
Subject: [PATCH 2/5] snapshots|pkg: umount without DETACH and nosync after
 umount

Signed-off-by: Wei Fu <fuweid89@gmail.com>
---
 pkg/testutil/helpers.go                  |  2 ++
 pkg/testutil/mount_linux.go              | 21 ---------------------
 pkg/testutil/mount_other.go              | 22 ----------------------
 snapshots/btrfs/btrfs_test.go            |  2 +-
 snapshots/testsuite/helpers.go           |  2 ++
 snapshots/testsuite/helpers_linux.go     | 21 ---------------------
 snapshots/testsuite/helpers_other.go     | 21 ---------------------
 snapshots/testsuite/testsuite.go         |  1 -
 snapshots/testsuite/testsuite_unix.go    |  6 ------
 snapshots/testsuite/testsuite_windows.go |  2 --
 10 files changed, 5 insertions(+), 95 deletions(-)
 delete mode 100644 pkg/testutil/mount_linux.go
 delete mode 100644 pkg/testutil/mount_other.go
 delete mode 100644 snapshots/testsuite/helpers_linux.go
 delete mode 100644 snapshots/testsuite/helpers_other.go

diff --git a/pkg/testutil/helpers.go b/pkg/testutil/helpers.go
index 850f51f83..81bf54b24 100644
--- a/pkg/testutil/helpers.go
+++ b/pkg/testutil/helpers.go
@@ -28,6 +28,8 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
+const umountflags int = 0
+
 var rootEnabled bool
 
 func init() {
diff --git a/pkg/testutil/mount_linux.go b/pkg/testutil/mount_linux.go
deleted file mode 100644
index 9c4cf8c16..000000000
--- a/pkg/testutil/mount_linux.go
+++ /dev/null
@@ -1,21 +0,0 @@
-/*
-   Copyright The containerd Authors.
-
-   Licensed under the Apache License, Version 2.0 (the "License");
-   you may not use this file except in compliance with the License.
-   You may obtain a copy of the License at
-
-       http://www.apache.org/licenses/LICENSE-2.0
-
-   Unless required by applicable law or agreed to in writing, software
-   distributed under the License is distributed on an "AS IS" BASIS,
-   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-   See the License for the specific language governing permissions and
-   limitations under the License.
-*/
-
-package testutil
-
-import "golang.org/x/sys/unix"
-
-const umountflags int = unix.MNT_DETACH
diff --git a/pkg/testutil/mount_other.go b/pkg/testutil/mount_other.go
deleted file mode 100644
index b1aa7d460..000000000
--- a/pkg/testutil/mount_other.go
+++ /dev/null
@@ -1,22 +0,0 @@
-//go:build !linux
-// +build !linux
-
-/*
-   Copyright The containerd Authors.
-
-   Licensed under the Apache License, Version 2.0 (the "License");
-   you may not use this file except in compliance with the License.
-   You may obtain a copy of the License at
-
-       http://www.apache.org/licenses/LICENSE-2.0
-
-   Unless required by applicable law or agreed to in writing, software
-   distributed under the License is distributed on an "AS IS" BASIS,
-   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-   See the License for the specific language governing permissions and
-   limitations under the License.
-*/
-
-package testutil
-
-const umountflags int = 0
diff --git a/snapshots/btrfs/btrfs_test.go b/snapshots/btrfs/btrfs_test.go
index 0671d15c4..02eb93d37 100644
--- a/snapshots/btrfs/btrfs_test.go
+++ b/snapshots/btrfs/btrfs_test.go
@@ -102,7 +102,7 @@ func boltSnapshotter(t *testing.T) func(context.Context, string) (snapshots.Snap
 			if err := snapshotter.Close(); err != nil {
 				return err
 			}
-			err := mount.UnmountAll(root, unix.MNT_DETACH)
+			err := mount.UnmountAll(root, 0)
 			if cerr := loop.Close(); cerr != nil {
 				err = fmt.Errorf("device cleanup failed: %w", cerr)
 			}
diff --git a/snapshots/testsuite/helpers.go b/snapshots/testsuite/helpers.go
index 4315db8ff..8032418fc 100644
--- a/snapshots/testsuite/helpers.go
+++ b/snapshots/testsuite/helpers.go
@@ -27,6 +27,8 @@ import (
 	"github.com/containerd/continuity/fs/fstest"
 )
 
+const umountflags int = 0
+
 func applyToMounts(m []mount.Mount, work string, a fstest.Applier) (err error) {
 	td, err := os.MkdirTemp(work, "prepare")
 	if err != nil {
diff --git a/snapshots/testsuite/helpers_linux.go b/snapshots/testsuite/helpers_linux.go
deleted file mode 100644
index 9e4aac356..000000000
--- a/snapshots/testsuite/helpers_linux.go
+++ /dev/null
@@ -1,21 +0,0 @@
-/*
-   Copyright The containerd Authors.
-
-   Licensed under the Apache License, Version 2.0 (the "License");
-   you may not use this file except in compliance with the License.
-   You may obtain a copy of the License at
-
-       http://www.apache.org/licenses/LICENSE-2.0
-
-   Unless required by applicable law or agreed to in writing, software
-   distributed under the License is distributed on an "AS IS" BASIS,
-   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-   See the License for the specific language governing permissions and
-   limitations under the License.
-*/
-
-package testsuite
-
-import "golang.org/x/sys/unix"
-
-const umountflags int = unix.MNT_DETACH
diff --git a/snapshots/testsuite/helpers_other.go b/snapshots/testsuite/helpers_other.go
deleted file mode 100644
index d39ec0734..000000000
--- a/snapshots/testsuite/helpers_other.go
+++ /dev/null
@@ -1,21 +0,0 @@
-//go:build !linux
-
-/*
-   Copyright The containerd Authors.
-
-   Licensed under the Apache License, Version 2.0 (the "License");
-   you may not use this file except in compliance with the License.
-   You may obtain a copy of the License at
-
-       http://www.apache.org/licenses/LICENSE-2.0
-
-   Unless required by applicable law or agreed to in writing, software
-   distributed under the License is distributed on an "AS IS" BASIS,
-   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-   See the License for the specific language governing permissions and
-   limitations under the License.
-*/
-
-package testsuite
-
-const umountflags int = 0
diff --git a/snapshots/testsuite/testsuite.go b/snapshots/testsuite/testsuite.go
index 7afbd953e..36982adab 100644
--- a/snapshots/testsuite/testsuite.go
+++ b/snapshots/testsuite/testsuite.go
@@ -959,7 +959,6 @@ func check128LayersMount(name string) func(ctx context.Context, t *testing.T, sn
 				t.Fatalf("[layer %d] preparing doesn't equal to flat after apply: %+v", i, err)
 			}
 
-			sync()
 			testutil.Unmount(t, preparing)
 
 			parent = filepath.Join(work, fmt.Sprintf("committed-%d", i))
diff --git a/snapshots/testsuite/testsuite_unix.go b/snapshots/testsuite/testsuite_unix.go
index 8a274ce24..e37cf86a1 100644
--- a/snapshots/testsuite/testsuite_unix.go
+++ b/snapshots/testsuite/testsuite_unix.go
@@ -20,8 +20,6 @@ package testsuite
 
 import (
 	"syscall"
-
-	"golang.org/x/sys/unix"
 )
 
 func clearMask() func() {
@@ -30,7 +28,3 @@ func clearMask() func() {
 		syscall.Umask(oldumask)
 	}
 }
-
-func sync() {
-	unix.Sync()
-}
diff --git a/snapshots/testsuite/testsuite_windows.go b/snapshots/testsuite/testsuite_windows.go
index 382a85978..a3cb82fbf 100644
--- a/snapshots/testsuite/testsuite_windows.go
+++ b/snapshots/testsuite/testsuite_windows.go
@@ -19,5 +19,3 @@ package testsuite
 func clearMask() func() {
 	return func() {}
 }
-
-func sync() {}

From 7de95cbc4cb35d372442cd4ed1ce6c837568d22a Mon Sep 17 00:00:00 2001
From: Wei Fu <fuweid89@gmail.com>
Date: Thu, 15 Jun 2023 14:28:57 +0000
Subject: [PATCH 3/5] snapshots/blockfile: deflaky the testsuite

* Use direct-io mode to reduce IO.

* Add testViewHook helper to recovery the backing file since the ext4
  might need writable permission to handle recovery. If the backing file
  needs recovery and it's for View snapshot, the readonly mount will
  cause error.

* Use 8 MiB as capacity to reduce the IO.

Signed-off-by: Wei Fu <fuweid89@gmail.com>
---
 snapshots/blockfile/blockfile.go              | 71 ++++++++++++++--
 .../blockfile/blockfile_loopsetup_test.go     | 81 ++++++++++++++-----
 2 files changed, 125 insertions(+), 27 deletions(-)

diff --git a/snapshots/blockfile/blockfile.go b/snapshots/blockfile/blockfile.go
index dd6257936..16666f199 100644
--- a/snapshots/blockfile/blockfile.go
+++ b/snapshots/blockfile/blockfile.go
@@ -19,6 +19,7 @@ package blockfile
 import (
 	"context"
 	"fmt"
+	"io"
 	"os"
 	"path/filepath"
 
@@ -27,10 +28,11 @@ import (
 	"github.com/containerd/containerd/plugin"
 	"github.com/containerd/containerd/snapshots"
 	"github.com/containerd/containerd/snapshots/storage"
-
-	"github.com/containerd/continuity/fs"
 )
 
+// viewHookHelper is only used in test for recover the filesystem.
+type viewHookHelper func(backingFile string, fsType string, defaultOpts []string) error
+
 // SnapshotterConfig holds the configurable properties for the blockfile snapshotter
 type SnapshotterConfig struct {
 	// recreateScratch is whether scratch should be recreated even
@@ -44,6 +46,17 @@ type SnapshotterConfig struct {
 
 	// mountOptions are the base options added to the mount (defaults to ["loop"])
 	mountOptions []string
+
+	// testViewHookHelper is used to fsck or mount with rw to handle
+	// the recovery. If we mount ro for view snapshot, we might hit
+	// the issue like
+	//
+	//  (ext4) INFO: recovery required on readonly filesystem
+	//  (ext4) write access unavailable, cannot proceed (try mounting with noload)
+	//
+	// FIXME(fuweid): I don't hit the readonly issue in ssd storage. But it's
+	// easy to reproduce it in slow-storage.
+	testViewHookHelper viewHookHelper
 }
 
 // Opt is an option to configure the overlay snapshotter
@@ -55,7 +68,7 @@ func WithScratchFile(src string) Opt {
 	return func(root string, config *SnapshotterConfig) {
 		config.scratchGenerator = func(dst string) error {
 			// Copy src to dst
-			if err := fs.CopyFile(dst, src); err != nil {
+			if err := copyFileWithSync(dst, src); err != nil {
 				return fmt.Errorf("failed to copy scratch: %w", err)
 			}
 			return nil
@@ -78,12 +91,30 @@ func WithMountOptions(options []string) Opt {
 
 }
 
+// WithRecreateScratch is used to determine that scratch should be recreated
+// even if already exists.
+func WithRecreateScratch(recreate bool) Opt {
+	return func(root string, config *SnapshotterConfig) {
+		config.recreateScratch = recreate
+	}
+}
+
+// withViewHookHelper introduces hook for preparing snapshot for View. It
+// should be used in test only.
+func withViewHookHelper(fn viewHookHelper) Opt {
+	return func(_ string, config *SnapshotterConfig) {
+		config.testViewHookHelper = fn
+	}
+}
+
 type snapshotter struct {
 	root    string
 	scratch string
 	fsType  string
 	options []string
 	ms      *storage.MetaStore
+
+	testViewHookHelper viewHookHelper
 }
 
 // NewSnapshotter returns a Snapshotter which copies layers on the underlying
@@ -140,6 +171,8 @@ func NewSnapshotter(root string, opts ...Opt) (snapshots.Snapshotter, error) {
 		fsType:  config.fsType,
 		options: config.mountOptions,
 		ms:      ms,
+
+		testViewHookHelper: config.testViewHookHelper,
 	}, nil
 }
 
@@ -343,18 +376,27 @@ func (o *snapshotter) createSnapshot(ctx context.Context, kind snapshots.Kind, k
 			return fmt.Errorf("failed to create snapshot: %w", err)
 		}
 
+		var path string
 		if len(s.ParentIDs) == 0 || s.Kind == snapshots.KindActive {
-			path := o.getBlockFile(s.ID)
+			path = o.getBlockFile(s.ID)
 
 			if len(s.ParentIDs) > 0 {
-				if err = fs.CopyFile(path, o.getBlockFile(s.ParentIDs[0])); err != nil {
+				if err = copyFileWithSync(path, o.getBlockFile(s.ParentIDs[0])); err != nil {
 					return fmt.Errorf("copying of parent failed: %w", err)
 				}
 			} else {
-				if err = fs.CopyFile(path, o.scratch); err != nil {
+				if err = copyFileWithSync(path, o.scratch); err != nil {
 					return fmt.Errorf("copying of scratch failed: %w", err)
 				}
 			}
+		} else {
+			path = o.getBlockFile(s.ParentIDs[0])
+		}
+
+		if o.testViewHookHelper != nil {
+			if err := o.testViewHookHelper(path, o.fsType, o.options); err != nil {
+				return fmt.Errorf("failed to handle the viewHookHelper: %w", err)
+			}
 		}
 
 		return nil
@@ -401,3 +443,20 @@ func (o *snapshotter) mounts(s storage.Snapshot) []mount.Mount {
 func (o *snapshotter) Close() error {
 	return o.ms.Close()
 }
+
+func copyFileWithSync(target, source string) error {
+	src, err := os.Open(source)
+	if err != nil {
+		return fmt.Errorf("failed to open source %s: %w", source, err)
+	}
+	defer src.Close()
+	tgt, err := os.Create(target)
+	if err != nil {
+		return fmt.Errorf("failed to open target %s: %w", target, err)
+	}
+	defer tgt.Close()
+	defer tgt.Sync()
+
+	_, err = io.Copy(tgt, src)
+	return err
+}
diff --git a/snapshots/blockfile/blockfile_loopsetup_test.go b/snapshots/blockfile/blockfile_loopsetup_test.go
index 06b4dd306..bda55f58b 100644
--- a/snapshots/blockfile/blockfile_loopsetup_test.go
+++ b/snapshots/blockfile/blockfile_loopsetup_test.go
@@ -26,9 +26,6 @@ import (
 	"testing"
 
 	"github.com/containerd/containerd/mount"
-	"github.com/containerd/continuity/fs"
-	"github.com/containerd/continuity/testutil/loopback"
-	"golang.org/x/sys/unix"
 )
 
 func setupSnapshotter(t *testing.T) ([]Opt, error) {
@@ -37,52 +34,94 @@ func setupSnapshotter(t *testing.T) ([]Opt, error) {
 		t.Skipf("Could not find mkfs.ext4: %v", err)
 	}
 
-	loopbackSize := int64(128 << 20) // 128 MB
+	loopbackSize := int64(8 << 20) // 8 MB
 	if os.Getpagesize() > 4096 {
 		loopbackSize = int64(650 << 20) // 650 MB
 	}
 
-	loop, err := loopback.New(loopbackSize)
+	scratch := filepath.Join(t.TempDir(), "scratch")
+	scratchDevFile, err := os.OpenFile(scratch, os.O_RDWR|os.O_CREATE|os.O_EXCL, 0600)
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("failed to create %s: %w", scratch, err)
 	}
-	defer loop.Close()
 
-	if out, err := exec.Command(mkfs, loop.Device).CombinedOutput(); err != nil {
+	if err := scratchDevFile.Truncate(loopbackSize); err != nil {
+		scratchDevFile.Close()
+		return nil, fmt.Errorf("failed to resize %s file: %w", scratch, err)
+	}
+
+	if err := scratchDevFile.Sync(); err != nil {
+		scratchDevFile.Close()
+		return nil, fmt.Errorf("failed to sync %s file: %w", scratch, err)
+	}
+	scratchDevFile.Close()
+
+	if out, err := exec.Command(mkfs, scratch).CombinedOutput(); err != nil {
 		return nil, fmt.Errorf("failed to make ext4 filesystem (out: %q): %w", out, err)
 	}
-	// sync after a mkfs on the loopback before trying to mount the device
-	unix.Sync()
 
-	if err := testMount(t, loop.Device); err != nil {
-		return nil, err
-	}
+	defaultOpts := []string{"loop", "direct-io", "sync"}
 
-	scratch := filepath.Join(t.TempDir(), "scratch")
-	err = fs.CopyFile(scratch, loop.File)
-	if err != nil {
+	if err := testMount(t, scratch, defaultOpts); err != nil {
 		return nil, err
 	}
 
 	return []Opt{
 		WithScratchFile(scratch),
 		WithFSType("ext4"),
-		WithMountOptions([]string{"loop", "sync"}),
+		WithMountOptions(defaultOpts),
+		WithRecreateScratch(false), // reduce IO presure in CI
+		withViewHookHelper(testViewHook),
 	}, nil
 }
 
-func testMount(t *testing.T, device string) error {
+func testMount(t *testing.T, scratchFile string, opts []string) error {
 	root, err := os.MkdirTemp(t.TempDir(), "")
 	if err != nil {
 		return err
 	}
 	defer os.RemoveAll(root)
 
-	if out, err := exec.Command("mount", device, root).CombinedOutput(); err != nil {
-		return fmt.Errorf("failed to mount device %s (out: %q): %w", device, out, err)
+	m := []mount.Mount{
+		{
+			Type:    "ext4",
+			Source:  scratchFile,
+			Options: opts,
+		},
 	}
+
+	if err := mount.All(m, root); err != nil {
+		return fmt.Errorf("failed to mount device %s: %w", scratchFile, err)
+	}
+
 	if err := os.Remove(filepath.Join(root, "lost+found")); err != nil {
 		return err
 	}
-	return mount.UnmountAll(root, unix.MNT_DETACH)
+	return mount.UnmountAll(root, 0)
+}
+
+func testViewHook(backingFile string, fsType string, defaultOpts []string) error {
+	root, err := os.MkdirTemp("", "blockfile-testViewHook-XXXX")
+	if err != nil {
+		return err
+	}
+	defer os.RemoveAll(root)
+
+	// FIXME(fuweid): Mount with rw to force fs to handle recover
+	mountOpts := []mount.Mount{
+		{
+			Type:    fsType,
+			Source:  backingFile,
+			Options: defaultOpts,
+		},
+	}
+
+	if err := mount.All(mountOpts, root); err != nil {
+		return fmt.Errorf("failed to mount device %s: %w", backingFile, err)
+	}
+
+	if err := mount.UnmountAll(root, 0); err != nil {
+		return fmt.Errorf("failed to unmount device %s: %w", backingFile, err)
+	}
+	return nil
 }

From 59b0b39af05207a72ed4b1a01e00cb10d3867d3f Mon Sep 17 00:00:00 2001
From: Wei Fu <fuweid89@gmail.com>
Date: Sat, 17 Jun 2023 08:29:05 +0800
Subject: [PATCH 4/5] vendor: update github.com/containerd/continuity

Pin it with 1e0d26eb2381594984ee80989c9c229dbd930d9f

Signed-off-by: Wei Fu <fuweid89@gmail.com>
---
 go.mod                                        |  2 +-
 go.sum                                        |  4 +-
 integration/client/go.mod                     |  2 +-
 integration/client/go.sum                     |  4 +-
 .../containerd/continuity/fs/copy.go          | 12 ++---
 .../containerd/continuity/fs/copy_darwin.go   |  2 +-
 .../containerd/continuity/fs/copy_linux.go    | 46 -------------------
 .../containerd/continuity/fs/copy_unix.go     |  9 ----
 .../containerd/continuity/fs/copy_windows.go  |  8 ----
 .../containerd/continuity/fs/fstest/file.go   |  7 ++-
 vendor/modules.txt                            |  2 +-
 11 files changed, 17 insertions(+), 81 deletions(-)

diff --git a/go.mod b/go.mod
index e894c94c4..d7cb3c6b4 100644
--- a/go.mod
+++ b/go.mod
@@ -11,7 +11,7 @@ require (
 	github.com/containerd/btrfs/v2 v2.0.0
 	github.com/containerd/cgroups/v3 v3.0.1
 	github.com/containerd/console v1.0.3
-	github.com/containerd/continuity v0.4.0
+	github.com/containerd/continuity v0.4.2-0.20230616210509-1e0d26eb2381
 	github.com/containerd/fifo v1.1.0
 	github.com/containerd/go-cni v1.1.9
 	github.com/containerd/go-runc v1.1.0
diff --git a/go.sum b/go.sum
index 6cbb0331f..66008c9c6 100644
--- a/go.sum
+++ b/go.sum
@@ -232,8 +232,8 @@ github.com/containerd/continuity v0.0.0-20201208142359-180525291bb7/go.mod h1:kR
 github.com/containerd/continuity v0.0.0-20210208174643-50096c924a4e/go.mod h1:EXlVlkqNba9rJe3j7w3Xa924itAMLgZH4UD/Q4PExuQ=
 github.com/containerd/continuity v0.1.0/go.mod h1:ICJu0PwR54nI0yPEnJ6jcS+J7CZAUXrLh8lPo2knzsM=
 github.com/containerd/continuity v0.2.2/go.mod h1:pWygW9u7LtS1o4N/Tn0FoCFDIXZ7rxcMX7HX1Dmibvk=
-github.com/containerd/continuity v0.4.0 h1:3LDxKUf4kY/zOUxmdtbxDVYuJQSK+eVg1D/Yk2bbqWQ=
-github.com/containerd/continuity v0.4.0/go.mod h1:F6PTNCKepoxEaXLQp3wDAjygEnImnZ/7o4JzpodfroQ=
+github.com/containerd/continuity v0.4.2-0.20230616210509-1e0d26eb2381 h1:a5jOuoZHKBi2oH9JsfNqrrPpHhmrYU0NAte3M/EPudw=
+github.com/containerd/continuity v0.4.2-0.20230616210509-1e0d26eb2381/go.mod h1:F6PTNCKepoxEaXLQp3wDAjygEnImnZ/7o4JzpodfroQ=
 github.com/containerd/fifo v0.0.0-20180307165137-3d5202aec260/go.mod h1:ODA38xgv3Kuk8dQz2ZQXpnv/UZZUHUCL7pnLehbXgQI=
 github.com/containerd/fifo v0.0.0-20190226154929-a9fb20d87448/go.mod h1:ODA38xgv3Kuk8dQz2ZQXpnv/UZZUHUCL7pnLehbXgQI=
 github.com/containerd/fifo v0.0.0-20200410184934-f15a3290365b/go.mod h1:jPQ2IAeZRCYxpS/Cm1495vGFww6ecHmMk1YJH2Q5ln0=
diff --git a/integration/client/go.mod b/integration/client/go.mod
index 4404d56bc..8bc864ea4 100644
--- a/integration/client/go.mod
+++ b/integration/client/go.mod
@@ -8,7 +8,7 @@ require (
 	github.com/Microsoft/hcsshim/test v0.0.0-20210408205431-da33ecd607e1
 	github.com/containerd/cgroups/v3 v3.0.1
 	github.com/containerd/containerd v1.7.0 // see replace; the actual version of containerd is replaced with the code at the root of this repository
-	github.com/containerd/continuity v0.4.0
+	github.com/containerd/continuity v0.4.2-0.20230616210509-1e0d26eb2381
 	github.com/containerd/go-runc v1.1.0
 	github.com/containerd/ttrpc v1.2.2
 	github.com/containerd/typeurl/v2 v2.1.1
diff --git a/integration/client/go.sum b/integration/client/go.sum
index 4c4bdbf6d..3c127d40a 100644
--- a/integration/client/go.sum
+++ b/integration/client/go.sum
@@ -656,8 +656,8 @@ github.com/containerd/console v1.0.3 h1:lIr7SlA5PxZyMV30bDW0MGbiOPXwc63yRuCP0ARu
 github.com/containerd/console v1.0.3/go.mod h1:7LqA/THxQ86k76b8c/EMSiaJ3h1eZkMkXar0TQ1gf3U=
 github.com/containerd/continuity v0.0.0-20210208174643-50096c924a4e/go.mod h1:EXlVlkqNba9rJe3j7w3Xa924itAMLgZH4UD/Q4PExuQ=
 github.com/containerd/continuity v0.3.0/go.mod h1:wJEAIwKOm/pBZuBd0JmeTvnLquTB1Ag8espWhkykbPM=
-github.com/containerd/continuity v0.4.0 h1:3LDxKUf4kY/zOUxmdtbxDVYuJQSK+eVg1D/Yk2bbqWQ=
-github.com/containerd/continuity v0.4.0/go.mod h1:F6PTNCKepoxEaXLQp3wDAjygEnImnZ/7o4JzpodfroQ=
+github.com/containerd/continuity v0.4.2-0.20230616210509-1e0d26eb2381 h1:a5jOuoZHKBi2oH9JsfNqrrPpHhmrYU0NAte3M/EPudw=
+github.com/containerd/continuity v0.4.2-0.20230616210509-1e0d26eb2381/go.mod h1:F6PTNCKepoxEaXLQp3wDAjygEnImnZ/7o4JzpodfroQ=
 github.com/containerd/fifo v1.0.0/go.mod h1:ocF/ME1SX5b1AOlWi9r677YJmCPSwwWnQ9O123vzpE4=
 github.com/containerd/fifo v1.1.0 h1:4I2mbh5stb1u6ycIABlBw9zgtlK8viPI9QkQNRQEEmY=
 github.com/containerd/fifo v1.1.0/go.mod h1:bmC4NWMbXlt2EZ0Hc7Fx7QzTFxgPID13eH0Qu+MAb2o=
diff --git a/vendor/github.com/containerd/continuity/fs/copy.go b/vendor/github.com/containerd/continuity/fs/copy.go
index a1cae0f95..af3abdd4c 100644
--- a/vendor/github.com/containerd/continuity/fs/copy.go
+++ b/vendor/github.com/containerd/continuity/fs/copy.go
@@ -18,20 +18,13 @@ package fs
 
 import (
 	"fmt"
+	"io"
 	"os"
 	"path/filepath"
-	"sync"
 
 	"github.com/sirupsen/logrus"
 )
 
-var bufferPool = &sync.Pool{
-	New: func() interface{} {
-		buffer := make([]byte, 32*1024)
-		return &buffer
-	},
-}
-
 // XAttrErrorHandler transform a non-nil xattr error.
 // Return nil to ignore an error.
 // xattrKey can be empty for listxattr operation.
@@ -199,5 +192,6 @@ func openAndCopyFile(target, source string) error {
 	}
 	defer tgt.Close()
 
-	return copyFileContent(tgt, src)
+	_, err = io.Copy(tgt, src)
+	return err
 }
diff --git a/vendor/github.com/containerd/continuity/fs/copy_darwin.go b/vendor/github.com/containerd/continuity/fs/copy_darwin.go
index 73e5af1ec..97fc2e8ea 100644
--- a/vendor/github.com/containerd/continuity/fs/copy_darwin.go
+++ b/vendor/github.com/containerd/continuity/fs/copy_darwin.go
@@ -25,7 +25,7 @@ import (
 
 func copyFile(target, source string) error {
 	if err := unix.Clonefile(source, target, unix.CLONE_NOFOLLOW); err != nil {
-		if !errors.Is(err, unix.ENOTSUP) {
+		if !errors.Is(err, unix.ENOTSUP) && !errors.Is(err, unix.EXDEV) {
 			return fmt.Errorf("clonefile failed: %w", err)
 		}
 
diff --git a/vendor/github.com/containerd/continuity/fs/copy_linux.go b/vendor/github.com/containerd/continuity/fs/copy_linux.go
index 1906e5e01..48ac3fbd3 100644
--- a/vendor/github.com/containerd/continuity/fs/copy_linux.go
+++ b/vendor/github.com/containerd/continuity/fs/copy_linux.go
@@ -18,7 +18,6 @@ package fs
 
 import (
 	"fmt"
-	"io"
 	"os"
 	"syscall"
 
@@ -62,51 +61,6 @@ func copyFileInfo(fi os.FileInfo, src, name string) error {
 	return nil
 }
 
-const maxSSizeT = int64(^uint(0) >> 1)
-
-func copyFileContent(dst, src *os.File) error {
-	st, err := src.Stat()
-	if err != nil {
-		return fmt.Errorf("unable to stat source: %w", err)
-	}
-
-	size := st.Size()
-	first := true
-	srcFd := int(src.Fd())
-	dstFd := int(dst.Fd())
-
-	for size > 0 {
-		// Ensure that we are never trying to copy more than SSIZE_MAX at a
-		// time and at the same time avoids overflows when the file is larger
-		// than 4GB on 32-bit systems.
-		var copySize int
-		if size > maxSSizeT {
-			copySize = int(maxSSizeT)
-		} else {
-			copySize = int(size)
-		}
-		n, err := unix.CopyFileRange(srcFd, nil, dstFd, nil, copySize, 0)
-		if err != nil {
-			if (err != unix.ENOSYS && err != unix.EXDEV) || !first {
-				return fmt.Errorf("copy file range failed: %w", err)
-			}
-
-			buf := bufferPool.Get().(*[]byte)
-			_, err = io.CopyBuffer(dst, src, *buf)
-			bufferPool.Put(buf)
-			if err != nil {
-				return fmt.Errorf("userspace copy failed: %w", err)
-			}
-			return nil
-		}
-
-		first = false
-		size -= int64(n)
-	}
-
-	return nil
-}
-
 func copyXAttrs(dst, src string, excludes map[string]struct{}, errorHandler XAttrErrorHandler) error {
 	xattrKeys, err := sysx.LListxattr(src)
 	if err != nil {
diff --git a/vendor/github.com/containerd/continuity/fs/copy_unix.go b/vendor/github.com/containerd/continuity/fs/copy_unix.go
index dd957872b..1311250e1 100644
--- a/vendor/github.com/containerd/continuity/fs/copy_unix.go
+++ b/vendor/github.com/containerd/continuity/fs/copy_unix.go
@@ -21,7 +21,6 @@ package fs
 
 import (
 	"fmt"
-	"io"
 	"os"
 	"runtime"
 	"syscall"
@@ -61,14 +60,6 @@ func copyFileInfo(fi os.FileInfo, src, name string) error {
 	return nil
 }
 
-func copyFileContent(dst, src *os.File) error {
-	buf := bufferPool.Get().(*[]byte)
-	_, err := io.CopyBuffer(dst, src, *buf)
-	bufferPool.Put(buf)
-
-	return err
-}
-
 func copyXAttrs(dst, src string, excludes map[string]struct{}, errorHandler XAttrErrorHandler) error {
 	xattrKeys, err := sysx.LListxattr(src)
 	if err != nil {
diff --git a/vendor/github.com/containerd/continuity/fs/copy_windows.go b/vendor/github.com/containerd/continuity/fs/copy_windows.go
index 6ec13b989..1fad4c3ad 100644
--- a/vendor/github.com/containerd/continuity/fs/copy_windows.go
+++ b/vendor/github.com/containerd/continuity/fs/copy_windows.go
@@ -19,7 +19,6 @@ package fs
 import (
 	"errors"
 	"fmt"
-	"io"
 	"os"
 
 	winio "github.com/Microsoft/go-winio"
@@ -72,13 +71,6 @@ func copyFileInfo(fi os.FileInfo, src, name string) error {
 	return nil
 }
 
-func copyFileContent(dst, src *os.File) error {
-	buf := bufferPool.Get().(*[]byte)
-	_, err := io.CopyBuffer(dst, src, *buf)
-	bufferPool.Put(buf)
-	return err
-}
-
 func copyXAttrs(dst, src string, excludes map[string]struct{}, errorHandler XAttrErrorHandler) error {
 	return nil
 }
diff --git a/vendor/github.com/containerd/continuity/fs/fstest/file.go b/vendor/github.com/containerd/continuity/fs/fstest/file.go
index 574b67576..97e882eaf 100644
--- a/vendor/github.com/containerd/continuity/fs/fstest/file.go
+++ b/vendor/github.com/containerd/continuity/fs/fstest/file.go
@@ -65,7 +65,12 @@ func writeFileStream(name string, stream func() io.Reader, perm os.FileMode) App
 			return err
 		}
 		defer func() {
-			err := f.Close()
+			err := f.Sync()
+			if err != nil && retErr == nil {
+				retErr = err
+			}
+
+			err = f.Close()
 			if err != nil && retErr == nil {
 				retErr = err
 			}
diff --git a/vendor/modules.txt b/vendor/modules.txt
index 10a2c0b25..8c57824c9 100644
--- a/vendor/modules.txt
+++ b/vendor/modules.txt
@@ -98,7 +98,7 @@ github.com/containerd/cgroups/v3/cgroup2/stats
 # github.com/containerd/console v1.0.3
 ## explicit; go 1.13
 github.com/containerd/console
-# github.com/containerd/continuity v0.4.0
+# github.com/containerd/continuity v0.4.2-0.20230616210509-1e0d26eb2381
 ## explicit; go 1.19
 github.com/containerd/continuity
 github.com/containerd/continuity/devices

From a207b430e3ef623d412c8ceeaacfdd5949340c7b Mon Sep 17 00:00:00 2001
From: Wei Fu <fuweid89@gmail.com>
Date: Sat, 17 Jun 2023 08:42:02 +0800
Subject: [PATCH 5/5] snapshots/blockfile: fix lint issue

Signed-off-by: Wei Fu <fuweid89@gmail.com>
---
 snapshots/blockfile/blockfile.go | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/snapshots/blockfile/blockfile.go b/snapshots/blockfile/blockfile.go
index 16666f199..f1e376ae3 100644
--- a/snapshots/blockfile/blockfile.go
+++ b/snapshots/blockfile/blockfile.go
@@ -101,6 +101,8 @@ func WithRecreateScratch(recreate bool) Opt {
 
 // withViewHookHelper introduces hook for preparing snapshot for View. It
 // should be used in test only.
+//
+//nolint:nolintlint,unused // not used on all platforms
 func withViewHookHelper(fn viewHookHelper) Opt {
 	return func(_ string, config *SnapshotterConfig) {
 		config.testViewHookHelper = fn