Merge pull request #1 from cvmfs/upgrade_fs

Upgrade the snapshotter to support also unmount

Author: siscia

Makefile

@@ -4,3 +4,9 @@ all: cvmfs-snapshotter
 
 cvmfs-snapshotter: 
 	go build -o $(PREFIX)$@
+
+
+release: cvmfs-snapshotter
+	mkdir -p release/usr/local/bin
+	cp -r out/* release/usr/local/bin
+	cp -r script/config/* release/

cvmfs/cvmfs.go

@@ -6,6 +6,7 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
+	"sync"
 	"syscall"
 
 	"github.com/containerd/containerd/log"
@@ -22,23 +23,34 @@ const (
 	targetImageLayersLabel = "containerd.io/snapshot/cri.image-layers"
 )
 
-
 type filesystem struct {
-	repository    string
-	mountedLayers map[string]string
+	fsAbsoluteMountpoint string
+	mountedLayers        map[string]string
+	mountedLayersLock    sync.Mutex
 }
 
 type Config struct {
-	Repository string `toml:"repository" default:"unpacked.cern.ch"`
+	Repository         string `toml:"repository" default:"unpacked.cern.ch"`
+	AbsoluteMountpoint string `toml:"absolute-mountpoint" default:""`
 }
 
 func NewFilesystem(ctx context.Context, root string, config *Config) (snapshot.FileSystem, error) {
-	log.G(ctx).WithField("root", root).Warning("New fs")
-	repository := config.Repository
-	if repository == "" {
-		repository = "unpacked.cern.ch"
+	var absolutePath string
+	mountedLayersMap := make(map[string]string)
+	if config.AbsoluteMountpoint == "" {
+		repository := config.Repository
+		if repository == "" {
+			repository = "unpacked.cern.ch"
+		}
+		absolutePath = filepath.Join("/", "cvmfs", repository)
+	} else {
+		absolutePath = config.AbsoluteMountpoint
+	}
+	log.G(ctx).WithField("root", root).WithField("absolutePath", absolutePath).Info("Mounting new filesystem")
+	if _, err := os.Stat(absolutePath); err != nil {
+		log.G(ctx).WithField("absolutePath", absolutePath).Warning("Impossible to stat the absolute path, is the filesystem mounted properly? Error: ", err)
 	}
-	return &filesystem{repository: repository, mountedLayers: make(map[string]string)}, nil
+	return &filesystem{fsAbsoluteMountpoint: absolutePath, mountedLayers: mountedLayersMap}, nil
 }
 
 func (fs *filesystem) Mount(ctx context.Context, mountpoint string, labels map[string]string) error {
@@ -51,7 +63,7 @@ func (fs *filesystem) Mount(ctx context.Context, mountpoint string, labels map[s
 	}
 	digest = strings.Split(digest, ":")[1]
 	firstTwo := digest[0:2]
-	path := filepath.Join("/", "cvmfs", fs.repository, ".layers", firstTwo, digest, "layerfs")
+	path := filepath.Join(fs.fsAbsoluteMountpoint, ".layers", firstTwo, digest, "layerfs")
 	if _, err := os.Stat(path); os.IsNotExist(err) {
 		err = fmt.Errorf("layer %s not in the cvmfs repository", digest)
 		log.G(ctx).WithError(err).WithField("layer digest", digest).WithField("path", path).Debug("cvmfs: Layer not found")
@@ -63,13 +75,17 @@ func (fs *filesystem) Mount(ctx context.Context, mountpoint string, labels map[s
 		log.G(ctx).WithError(err).WithField("layer digest", digest).WithField("mountpoint", mountpoint).Debug("cvmfs: Error in bind mounting the layer.")
 		return err
 	}
+	fs.mountedLayersLock.Lock()
+	defer fs.mountedLayersLock.Unlock()
 	fs.mountedLayers[mountpoint] = path
 	return nil
 }
 
-func (fs *filesystem) Check(ctx context.Context, mountpoint string) error {
+func (fs *filesystem) Check(ctx context.Context, mountpoint string, labels map[string]string) error {
 	log.G(ctx).WithField("snapshotter", "cvmfs").WithField("mountpoint", mountpoint).Warning("checking layer")
+	fs.mountedLayersLock.Lock()
 	path, ok := fs.mountedLayers[mountpoint]
+	fs.mountedLayersLock.Unlock()
 	if !ok {
 		err := fmt.Errorf("Mountpoint: %s was not mounted", mountpoint)
 		log.G(ctx).WithError(err).WithField("mountpoint", mountpoint).Error("cvmfs: the requested mountpoint does not seem to be mounted")
@@ -92,3 +108,18 @@ func (fs *filesystem) Check(ctx context.Context, mountpoint string) error {
 	}
 	return statErr
 }
+
+func (fs *filesystem) Unmount(ctx context.Context, mountpoint string) error {
+	// maybe we lost track of something somehow, does not hurt to try to unmount the mountpoint anyway
+
+	fs.mountedLayersLock.Lock()
+	_, ok := fs.mountedLayers[mountpoint]
+	delete(fs.mountedLayers, mountpoint)
+	fs.mountedLayersLock.Unlock()
+
+	if !ok {
+		err := fmt.Errorf("Trying to unmount mountpoint that does not seems mounted: %s", mountpoint)
+		log.G(ctx).WithError(err).Error("Layer does not seems mounted.")
+	}
+	return syscall.Unmount(mountpoint, syscall.MNT_FORCE)
+}

go.mod

@@ -4,8 +4,8 @@ go 1.14
 
 require (
 	github.com/BurntSushi/toml v0.3.1
-	github.com/containerd/containerd v1.3.1-0.20200507183255-990076b731ec
-	github.com/containerd/stargz-snapshotter v0.0.0-20200609024515-95c85650d51d
+	github.com/containerd/containerd v1.4.0
+	github.com/containerd/stargz-snapshotter v0.0.0-20201007053350-9827a0b90aaa
 	github.com/sirupsen/logrus v1.6.0
 	google.golang.org/grpc v1.29.1
 )