Forward all labels to the snapshotter

This is primarily motivated by the desire to create windows containers
with a rootfs size larger than the snapshotter default.

This can be acheived with the `ctr run` command with the
`--snapshotter-label` argument. The snapshotter filters labels for which
it has an interest and ignores others, so this change simply forwards
all supplied labels instead of making an API change.

For the two cases below the commands run are:

1. `docker run --rm -it mcr.microsoft.com/windows/servercore:ltsc2022 powershell -Command "(gdr C).Free + (gdr C).Used"`
2. `docker run --label "containerd.io/snapshot/windows/rootfs.sizebytes=32212254720" --rm -it mcr.microsoft.com/windows/servercore:ltsc2022 powershell -Command "(gdr C).Free + (gdr C).Used"`

Before this change:
-------------------
Output from 1: `21339549696`
Output from 2: `21339549696`

After this change:
------------------
Output from 1: `21339549696`
Output from 2: `32076963840`

Author: mendsley

daemon/containerd/image_snapshot.go

@@ -21,7 +21,7 @@ import (
 )
 
 // CreateLayer creates a new layer for a container.
-func (i *ImageService) CreateLayer(ctr *container.Container, initFunc layer.MountInit) (container.RWLayer, error) {
+func (i *ImageService) CreateLayer(ctr *container.Container, initFunc layer.MountInit, labels map[string]string) (container.RWLayer, error) {
 	var descriptor *ocispec.Descriptor
 	if ctr.ImageManifest != nil {
 		descriptor = ctr.ImageManifest
@@ -31,7 +31,7 @@ func (i *ImageService) CreateLayer(ctr *container.Container, initFunc layer.Moun
 		StorageOpt: ctr.HostConfig.StorageOpt,
 	}
 
-	return i.createLayer(descriptor, ctr.ID, rwLayerOpts, initFunc)
+	return i.createLayer(descriptor, ctr.ID, rwLayerOpts, initFunc, labels)
 }
 
 // CreateLayerFromImage creates a new layer from an image
@@ -41,10 +41,10 @@ func (i *ImageService) CreateLayerFromImage(img *image.Image, layerName string,
 		descriptor = img.Details.ManifestDescriptor
 	}
 
-	return i.createLayer(descriptor, layerName, rwLayerOpts, nil)
+	return i.createLayer(descriptor, layerName, rwLayerOpts, nil, nil)
 }
 
-func (i *ImageService) createLayer(descriptor *ocispec.Descriptor, layerName string, rwLayerOpts *layer.CreateRWLayerOpts, initFunc layer.MountInit) (container.RWLayer, error) {
+func (i *ImageService) createLayer(descriptor *ocispec.Descriptor, layerName string, rwLayerOpts *layer.CreateRWLayerOpts, initFunc layer.MountInit, labels map[string]string) (container.RWLayer, error) {
 	ctx := context.TODO()
 	var parentSnapshot string
 	if descriptor != nil {
@@ -78,7 +78,11 @@ func (i *ImageService) createLayer(descriptor *ocispec.Descriptor, layerName str
 	if !i.idMapping.Empty() {
 		err = i.remapSnapshot(ctx, sn, layerName, parentSnapshot)
 	} else {
-		_, err = sn.Prepare(ctx, layerName, parentSnapshot)
+		sopts := []snapshots.Opt {
+			snapshots.WithLabels(labels),
+		}
+
+		_, err = sn.Prepare(ctx, layerName, parentSnapshot, sopts...)
 	}
 
 	if err != nil {

daemon/create.go

@@ -228,7 +228,7 @@ func (daemon *Daemon) create(ctx context.Context, daemonCfg *config.Config, opts
 	ctr.ImageManifest = imgManifest
 
 	// Set RWLayer for container after mount labels have been set
-	rwLayer, err := daemon.imageService.CreateLayer(ctr, setupInitLayer(daemon.idMapping.RootPair()))
+	rwLayer, err := daemon.imageService.CreateLayer(ctr, setupInitLayer(daemon.idMapping.RootPair()), opts.params.Config.Labels)
 	if err != nil {
 		return nil, errdefs.System(err)
 	}

daemon/image_service.go

@@ -47,7 +47,7 @@ type ImageService interface {
 	// Layers
 
 	GetImageAndReleasableLayer(ctx context.Context, refOrID string, opts backend.GetImageAndLayerOptions) (builder.Image, builder.ROLayer, error)
-	CreateLayer(container *container.Container, initFunc layer.MountInit) (container.RWLayer, error)
+	CreateLayer(container *container.Container, initFunc layer.MountInit, labels map[string]string) (container.RWLayer, error)
 	CreateLayerFromImage(img *image.Image, layerName string, rwLayerOpts *layer.CreateRWLayerOpts) (container.RWLayer, error)
 	GetLayerByID(cid string) (container.RWLayer, error)
 	LayerStoreStatus() [][2]string

daemon/images/service.go

@@ -118,7 +118,7 @@ func (i *ImageService) Children(_ context.Context, id image.ID) ([]image.ID, err
 // CreateLayer creates a filesystem layer for a container.
 // called from create.go
 // TODO: accept an opt struct instead of container?
-func (i *ImageService) CreateLayer(container *container.Container, initFunc layer.MountInit) (container.RWLayer, error) {
+func (i *ImageService) CreateLayer(container *container.Container, initFunc layer.MountInit, labels map[string]string) (container.RWLayer, error) {
 	var img *image.Image
 	if container.ImageID != "" {
 		containerImg, err := i.imageStore.Get(container.ImageID)