BACKPORT: take reference to RWLayer while committing/exporting

Upstream reference: moby#30696
Trello: https://trello.com/c/vNlHE2kV

Signed-off-by: Antonio Murdaca <runcom@redhat.com>

Author: runcom

container/state.go

@@ -322,13 +322,30 @@ func (s *State) ResetRemovalInProgress() {
 	s.Unlock()
 }
 
+// IsRemovalInProgress returns whether the RemovalInProgress flag is set.
+// Used by Container to check whether a container is being removed.
+func (s *State) IsRemovalInProgress() bool {
+	s.Lock()
+	res := s.RemovalInProgress
+	s.Unlock()
+	return res
+}
+
 // SetDead sets the container state to "dead"
 func (s *State) SetDead() {
 	s.Lock()
 	s.Dead = true
 	s.Unlock()
 }
 
+// IsDead returns whether the Dead flag is set. Used by Container to check whether a container is dead.
+func (s *State) IsDead() bool {
+	s.Lock()
+	res := s.Dead
+	s.Unlock()
+	return res
+}
+
 // Error returns current error for the state.
 func (s *State) Error() string {
 	return s.ErrorMsg

daemon/commit.go

@@ -14,7 +14,6 @@ import (
 	"github.com/docker/docker/image"
 	"github.com/docker/docker/layer"
 	"github.com/docker/docker/pkg/archive"
-	"github.com/docker/docker/pkg/ioutils"
 	"github.com/docker/docker/reference"
 	containertypes "github.com/docker/engine-api/types/container"
 	"github.com/docker/go-connections/nat"
@@ -128,6 +127,14 @@ func (daemon *Daemon) Commit(name string, c *backend.ContainerCommitConfig) (str
 		return "", fmt.Errorf("Windows does not support commit of a running container")
 	}
 
+	if container.IsDead() {
+		return "", fmt.Errorf("You cannot commit container %s which is Dead", container.ID)
+	}
+
+	if container.IsRemovalInProgress() {
+		return "", fmt.Errorf("You cannot commit container %s which is being removed", container.ID)
+	}
+
 	if c.Pause && !container.IsPaused() {
 		daemon.containerPause(container)
 		defer daemon.containerUnpause(container)
@@ -246,18 +253,15 @@ func (daemon *Daemon) Commit(name string, c *backend.ContainerCommitConfig) (str
 }
 
 func (daemon *Daemon) exportContainerRw(container *container.Container) (archive.Archive, error) {
-	if err := daemon.Mount(container); err != nil {
+	rwLayer, err := daemon.layerStore.GetRWLayer(container.ID)
+	if err != nil {
 		return nil, err
 	}
+	defer daemon.layerStore.ReleaseRWLayer(rwLayer)
 
-	archive, err := container.RWLayer.TarStream()
+	archive, err := rwLayer.TarStream()
 	if err != nil {
-		daemon.Unmount(container) // logging is already handled in the `Unmount` function
 		return nil, err
 	}
-	return ioutils.NewReadCloserWrapper(archive, func() error {
-			archive.Close()
-			return container.RWLayer.Unmount()
-		}),
-		nil
+	return archive, nil
 }

daemon/export.go

@@ -17,6 +17,14 @@ func (daemon *Daemon) ContainerExport(name string, out io.Writer) error {
 		return err
 	}
 
+	if container.IsDead() {
+		return fmt.Errorf("You cannot export container %s which is Dead", container.ID)
+	}
+
+	if container.IsRemovalInProgress() {
+		return fmt.Errorf("You cannot export container %s which is being removed", container.ID)
+	}
+
 	data, err := daemon.containerExport(container)
 	if err != nil {
 		return fmt.Errorf("Error exporting container %s: %v", name, err)
@@ -30,8 +38,19 @@ func (daemon *Daemon) ContainerExport(name string, out io.Writer) error {
 	return nil
 }
 
-func (daemon *Daemon) containerExport(container *container.Container) (archive.Archive, error) {
-	if err := daemon.Mount(container); err != nil {
+func (daemon *Daemon) containerExport(container *container.Container) (arch archive.Archive, err error) {
+	rwLayer, err := daemon.layerStore.GetRWLayer(container.ID)
+	if err != nil {
+		return nil, err
+	}
+	defer func() {
+		if err != nil {
+			daemon.layerStore.ReleaseRWLayer(rwLayer)
+		}
+	}()
+
+	_, err = rwLayer.Mount(container.GetMountLabel())
+	if err != nil {
 		return nil, err
 	}
 
@@ -42,12 +61,13 @@ func (daemon *Daemon) containerExport(container *container.Container) (archive.A
 		GIDMaps:     gidMaps,
 	})
 	if err != nil {
-		daemon.Unmount(container)
+		rwLayer.Unmount()
 		return nil, err
 	}
-	arch := ioutils.NewReadCloserWrapper(archive, func() error {
+	arch = ioutils.NewReadCloserWrapper(archive, func() error {
 		err := archive.Close()
-		daemon.Unmount(container)
+		rwLayer.Unmount()
+		daemon.layerStore.ReleaseRWLayer(rwLayer)
 		return err
 	})
 	daemon.LogContainerEvent(container, "export")