1. docker
  2. Commit 8d7c7bd2e3aba3bba72264d477c56444c5dc6350
Browse code

Fix potential race in volume creation

Docker-DCO-1.1-Signed-off-by: Brian Goff <cpuguy83@gmail.com> (github: cpuguy83)

Brian Goff authored on 2014/09/27 09:42:24
Showing 2 changed files
daemon/volumes.go
History View file @ 8d7c7bd
... ... 
@@ -111,12 +111,9 @@ func (container *Container) parseVolumeMountConfig() (map[string]*Mount, error)
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 			return nil, err
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 		}
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 		// Check if a volume already exists for this and use it
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-		vol := container.daemon.volumes.Get(path)
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-		if vol == nil {
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-			vol, err = container.daemon.volumes.NewVolume(path, writable)
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-			if err != nil {
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-				return nil, err
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-			}
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+		vol, err := container.daemon.volumes.FindOrCreateVolume(path, writable)
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+		if err != nil {
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+			return nil, err
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 		}
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 		mounts[mountToPath] = &Mount{container: container, volume: vol, MountToPath: mountToPath, Writable: writable}
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 	}
... ... 
@@ -128,7 +125,7 @@ func (container *Container) parseVolumeMountConfig() (map[string]*Mount, error)
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 			continue
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 		}
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-		vol, err := container.daemon.volumes.NewVolume("", true)
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+		vol, err := container.daemon.volumes.FindOrCreateVolume("", true)
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 		if err != nil {
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 			return nil, err
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 		}
volumes/repository.go
History View file @ 8d7c7bd
... ... 
@@ -38,7 +38,7 @@ func NewRepository(configPath string, driver graphdriver.Driver) (*Repository, e
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 	return repo, repo.restore()
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 }
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-func (r *Repository) NewVolume(path string, writable bool) (*Volume, error) {
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+func (r *Repository) newVolume(path string, writable bool) (*Volume, error) {
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 	var (
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 		isBindMount bool
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 		err         error
... ... 
@@ -73,10 +73,8 @@ func (r *Repository) NewVolume(path string, writable bool) (*Volume, error) {
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 	if err := v.initialize(); err != nil {
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 		return nil, err
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 	}
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-	if err := r.Add(v); err != nil {
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-		return nil, err
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-	}
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-	return v, nil
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+
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+	return v, r.add(v)
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 }
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 func (r *Repository) restore() error {
... ... 
@@ -113,6 +111,10 @@ func (r *Repository) get(path string) *Volume {
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 func (r *Repository) Add(volume *Volume) error {
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 	r.lock.Lock()
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 	defer r.lock.Unlock()
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+	return r.add(volume)
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+}
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+
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+func (r *Repository) add(volume *Volume) error {
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 	if vol := r.get(volume.Path); vol != nil {
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 		return fmt.Errorf("Volume exists: %s", volume.ID)
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 	}
... ... 
@@ -175,3 +177,18 @@ func (r *Repository) createNewVolumePath(id string) (string, error) {
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 	return path, nil
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 }
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+
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+func (r *Repository) FindOrCreateVolume(path string, writable bool) (*Volume, error) {
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+	r.lock.Lock()
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+	defer r.lock.Unlock()
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+
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+	if path == "" {
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+		return r.newVolume(path, writable)
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+	}
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+
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+	if v := r.get(path); v != nil {
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+		return v, nil
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+	}
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+
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+	return r.newVolume(path, writable)
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+}