rootfs: use new ctx to cleanup instead of canceled one

fuweid · fuweid · commit 09b184c15a2f · 2019-08-27T11:27:34.000+08:00
rootfs.CreateDiff might be canceled by context for some reason. Based on
this case, the defer function should use the new ctx to do cleanup
temporary snapshotter instead of the canceled one.

Signed-off-by: Wei Fu &lt;fuweid89@gmail.com&gt;
diff --git a/rootfs/diff.go b/rootfs/diff.go
@@ -22,6 +22,7 @@ import (
 
 	"github.com/containerd/containerd/diff"
 	"github.com/containerd/containerd/mount"
+	"github.com/containerd/containerd/namespaces"
 	"github.com/containerd/containerd/snapshots"
 	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
 )
@@ -31,6 +32,13 @@ import (
 // the content creation and the provided snapshotter and mount differ are used
 // for calculating the diff. The descriptor for the layer diff is returned.
 func CreateDiff(ctx context.Context, snapshotID string, sn snapshots.Snapshotter, d diff.Comparer, opts ...diff.Opt) (ocispec.Descriptor, error) {
+	// dctx is used to handle cleanup things just in case the param ctx
+	// has been canceled, which causes that the defer cleanup fails.
+	dctx := context.Background()
+	if ns, ok := namespaces.Namespace(ctx); ok {
+		dctx = namespaces.WithNamespace(dctx, ns)
+	}
+
 	info, err := sn.Stat(ctx, snapshotID)
 	if err != nil {
 		return ocispec.Descriptor{}, err
@@ -41,7 +49,7 @@ func CreateDiff(ctx context.Context, snapshotID string, sn snapshots.Snapshotter
 	if err != nil {
 		return ocispec.Descriptor{}, err
 	}
-	defer sn.Remove(ctx, lowerKey)
+	defer sn.Remove(dctx, lowerKey)
 
 	var upper []mount.Mount
 	if info.Kind == snapshots.KindActive {
@@ -55,7 +63,7 @@ func CreateDiff(ctx context.Context, snapshotID string, sn snapshots.Snapshotter
 		if err != nil {
 			return ocispec.Descriptor{}, err
 		}
-		defer sn.Remove(ctx, upperKey)
+		defer sn.Remove(dctx, upperKey)
 	}
 
 	return d.Compare(ctx, lower, upper, opts...)
