Call temp mounts and unmount in containerd server

Fixes #2004

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

cmd/containerd/command/main.go

@@ -12,6 +12,7 @@ import (
 	"time"
 
 	"github.com/containerd/containerd/log"
+	"github.com/containerd/containerd/mount"
 	"github.com/containerd/containerd/server"
 	"github.com/containerd/containerd/sys"
 	"github.com/containerd/containerd/version"
@@ -95,6 +96,14 @@ func App() *cli.App {
 		if err := applyFlags(context, config); err != nil {
 			return err
 		}
+		// cleanup temp mounts
+		if err := mount.SetTempMountLocation(filepath.Join(config.Root, "tmpmounts")); err != nil {
+			return errors.Wrap(err, "creating temp mount location")
+		}
+		// unmount all temp mounts on boot for the server
+		if err := mount.CleanupTempMounts(0); err != nil {
+			return errors.Wrap(err, "unmounting temp mounts")
+		}
 		address := config.GRPC.Address
 		if address == "" {
 			return errors.New("grpc address cannot be empty")

container_opts_unix.go

@@ -188,7 +188,7 @@ func withRemappedSnapshotBase(id string, i Image, uid, gid uint32, readonly bool
 }
 
 func remapRootFS(ctx context.Context, mounts []mount.Mount, uid, gid uint32) error {
-	return mount.DefaultTempLocation.Mount(ctx, mounts, func(root string) error {
+	return mount.WithTempMount(ctx, mounts, func(root string) error {
 		return filepath.Walk(root, incrementFS(root, uid, gid))
 	})
 }

diff/apply/apply.go

@@ -56,7 +56,7 @@ func (s *fsApplier) Apply(ctx context.Context, desc ocispec.Descriptor, mounts [
 	}
 
 	var ocidesc ocispec.Descriptor
-	if err := mount.DefaultTempLocation.Mount(ctx, mounts, func(root string) error {
+	if err := mount.WithTempMount(ctx, mounts, func(root string) error {
 		ra, err := s.store.ReaderAt(ctx, desc.Digest)
 		if err != nil {
 			return errors.Wrap(err, "failed to get reader from content store")

diff/walking/differ.go

@@ -62,8 +62,8 @@ func (s *walkingDiff) Compare(ctx context.Context, lower, upper []mount.Mount, o
 	}
 
 	var ocidesc ocispec.Descriptor
-	if err := mount.DefaultTempLocation.Mount(ctx, lower, func(lowerRoot string) error {
-		return mount.DefaultTempLocation.Mount(ctx, upper, func(upperRoot string) error {
+	if err := mount.WithTempMount(ctx, lower, func(lowerRoot string) error {
+		return mount.WithTempMount(ctx, upper, func(upperRoot string) error {
 			var newReference bool
 			if config.Reference == "" {
 				newReference = true

mount/temp.go

@@ -4,46 +4,18 @@ import (
 	"context"
 	"io/ioutil"
 	"os"
-	"path/filepath"
-	"sort"
-	"strings"
 
 	"github.com/containerd/containerd/log"
 	"github.com/pkg/errors"
 )
 
-func init() {
-	t, err := TempLocation("/tmp")
-	if err != nil {
-		panic(err)
-	}
-	DefaultTempLocation = t
-}
-
-var DefaultTempLocation TempMounts
-
-func TempLocation(root string) (TempMounts, error) {
-	root, err := filepath.Abs(root)
-	if err != nil {
-		return DefaultTempLocation, err
-	}
-	if err := os.MkdirAll(root, 0700); err != nil {
-		return DefaultTempLocation, err
-	}
-	return TempMounts{
-		root: root,
-	}, nil
-}
-
-type TempMounts struct {
-	root string
-}
+var tempMountLocation = os.TempDir()
 
 // WithTempMount mounts the provided mounts to a temp dir, and pass the temp dir to f.
 // The mounts are valid during the call to the f.
 // Finally we will unmount and remove the temp dir regardless of the result of f.
-func (t TempMounts) Mount(ctx context.Context, mounts []Mount, f func(root string) error) (err error) {
-	root, uerr := ioutil.TempDir(t.root, "containerd-WithTempMount")
+func WithTempMount(ctx context.Context, mounts []Mount, f func(root string) error) (err error) {
+	root, uerr := ioutil.TempDir(tempMountLocation, "containerd-mount")
 	if uerr != nil {
 		return errors.Wrapf(uerr, "failed to create temp dir")
 	}
@@ -76,43 +48,3 @@ func (t TempMounts) Mount(ctx context.Context, mounts []Mount, f func(root strin
 	}
 	return errors.Wrapf(f(root), "mount callback failed on %s", root)
 }
-
-// Unmount all temp mounts and remove the directories
-func (t TempMounts) Unmount(flags int) error {
-	mounts, err := PID(os.Getpid())
-	if err != nil {
-		return err
-	}
-	var toUnmount []string
-	for _, m := range mounts {
-		if strings.HasPrefix(m.Mountpoint, t.root) {
-			toUnmount = append(toUnmount, m.Mountpoint)
-		}
-	}
-	sort.Sort(sort.Reverse(mountSorter(toUnmount)))
-	for _, path := range toUnmount {
-		if err := UnmountAll(path, flags); err != nil {
-			return err
-		}
-		if err := os.Remove(path); err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
-type mountSorter []string
-
-func (by mountSorter) Len() int {
-	return len(by)
-}
-
-func (by mountSorter) Less(i, j int) bool {
-	is := strings.Split(by[i], string(os.PathSeparator))
-	js := strings.Split(by[j], string(os.PathSeparator))
-	return len(is) < len(js)
-}
-
-func (by mountSorter) Swap(i, j int) {
-	by[i], by[j] = by[j], by[i]
-}

mount/temp_unix.go

@@ -0,0 +1,47 @@
+// +build !windows
+
+package mount
+
+import (
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+)
+
+// SetTempMountLocation sets the temporary mount location
+func SetTempMountLocation(root string) error {
+	root, err := filepath.Abs(root)
+	if err != nil {
+		return err
+	}
+	if err := os.MkdirAll(root, 0700); err != nil {
+		return err
+	}
+	tempMountLocation = root
+	return nil
+}
+
+// CleanupTempMounts all temp mounts and remove the directories
+func CleanupTempMounts(flags int) error {
+	mounts, err := Self()
+	if err != nil {
+		return err
+	}
+	var toUnmount []string
+	for _, m := range mounts {
+		if strings.HasPrefix(m.Mountpoint, tempMountLocation) {
+			toUnmount = append(toUnmount, m.Mountpoint)
+		}
+	}
+	sort.Sort(sort.Reverse(sort.StringSlice(toUnmount)))
+	for _, path := range toUnmount {
+		if err := UnmountAll(path, flags); err != nil {
+			return err
+		}
+		if err := os.Remove(path); err != nil {
+			return err
+		}
+	}
+	return nil
+}

mount/temp_unsupported.go

@@ -0,0 +1,13 @@
+// +build windows
+
+package mount
+
+// SetTempMountLocation sets the temporary mount location
+func SetTempMountLocation(root string) error {
+	return nil
+}
+
+// CleanupTempMounts all temp mounts and remove the directories
+func CleanupTempMounts(flags int) error {
+	return nil
+}

oci/spec_opts_unix.go

@@ -287,7 +287,7 @@ func WithUserID(uid uint32) SpecOpts {
 		if err != nil {
 			return err
 		}
-		return mount.DefaultTempLocation.Mount(ctx, mounts, func(root string) error {
+		return mount.WithTempMount(ctx, mounts, func(root string) error {
 			uuid, ugid, err := getUIDGIDFromPath(root, func(u user.User) bool {
 				return u.Uid == int(uid)
 			})
@@ -334,7 +334,7 @@ func WithUsername(username string) SpecOpts {
 		if err != nil {
 			return err
 		}
-		return mount.DefaultTempLocation.Mount(ctx, mounts, func(root string) error {
+		return mount.WithTempMount(ctx, mounts, func(root string) error {
 			uid, gid, err := getUIDGIDFromPath(root, func(u user.User) bool {
 				return u.Name == username
 			})