func (d *DaemonConfig) completeRemove(req *config.VolumeRequest, vc *config.Volume) error {
	if err := control.RemoveVolume(vc, d.Global.Timeout); err != nil && err != errors.NoActionTaken {
		logrus.Warn(errors.RemoveImage.Combine(errored.New(vc.String())).Combine(err))
	}

	return d.removeVolume(req, vc)
}

func (d *DaemonConfig) removeVolume(req *config.VolumeRequest, vc *config.Volume) error {
	if err := d.Config.RemoveVolume(req.Policy, req.Name); err != nil {
		return errors.ClearVolume.Combine(errored.New(vc.String())).Combine(err)
	}

	return nil
}

func (dc *DaemonConfig) pruneSnapshots(val *config.Volume) {
	logrus.Infof("starting snapshot prune for %q", val.VolumeName)
	if val.Backends.Snapshot == "" {
		logrus.Debugf("Snapshot driver for volume %v was empty, not snapshotting.", val)
		return
	}

	uc := &config.UseSnapshot{
		Volume: val.String(),
		Reason: lock.ReasonSnapshotPrune,
	}

	stopChan, err := lock.NewDriver(dc.Config).AcquireWithTTLRefresh(uc, dc.Global.TTL, dc.Global.Timeout)
	if err != nil {
		logrus.Error(errors.LockFailed.Combine(err))
		return
	}

	defer func() { stopChan <- struct{}{} }()

	driver, err := backend.NewSnapshotDriver(val.Backends.Snapshot)
	if err != nil {
		logrus.Errorf("failed to get driver: %v", err)
		return
	}

	driverOpts := storage.DriverOptions{
		Volume: storage.Volume{
			Name: val.String(),
			Params: storage.Params{
				"pool": val.DriverOptions["pool"],
			},
		},
		Timeout: dc.Global.Timeout,
	}

	list, err := driver.ListSnapshots(driverOpts)
	if err != nil {
		logrus.Errorf("Could not list snapshots for volume %q: %v", val.VolumeName, err)
		return
	}

	logrus.Debugf("Volume %q: keeping %d snapshots", val, val.RuntimeOptions.Snapshot.Keep)

	toDeleteCount := len(list) - int(val.RuntimeOptions.Snapshot.Keep)
	if toDeleteCount < 0 {
		return
	}

	for i := 0; i < toDeleteCount; i++ {
		logrus.Infof("Removing snapshot %q for volume %q", list[i], val.VolumeName)
		if err := driver.RemoveSnapshot(list[i], driverOpts); err != nil {
			logrus.Errorf("Removing snapshot %q for volume %q failed: %v", list[i], val.VolumeName, err)
		}
	}
}

func (d *DaemonConfig) handleForceRemoveLock(req *config.VolumeRequest, vc *config.Volume, locks []config.UseLocker) error {
	exists, err := control.ExistsVolume(vc, d.Global.Timeout)
	if err != nil && err != errors.NoActionTaken {
		return errors.RemoveVolume.Combine(errored.New(vc.String())).Combine(err)
	}

	if err == errors.NoActionTaken {
		if err := d.completeRemove(req, vc); err != nil {
			return err
		}

		d.removeVolumeUse(locks[0], vc)
	}

	if err != nil {
		return errors.RemoveVolume.Combine(errored.New(vc.String())).Combine(err)
	}

	if !exists {
		d.removeVolume(req, vc)
		return errors.RemoveVolume.Combine(errored.New(vc.String())).Combine(errors.NotExists)
	}

	err = d.completeRemove(req, vc)
	if err != nil {
		return errors.RemoveVolume.Combine(errored.New(vc.String())).Combine(errors.NotExists)
	}

	d.removeVolumeUse(locks[0], vc)
	return nil
}

func (d *DaemonConfig) createRemoveLocks(vc *config.Volume) ([]config.UseLocker, error) {
	hostname, err := os.Hostname()
	if err != nil {
		return nil, errors.GetHostname.Combine(err)
	}

	uc := &config.UseMount{
		Volume:   vc.String(),
		Reason:   lock.ReasonRemove,
		Hostname: hostname,
	}

	snapUC := &config.UseSnapshot{
		Volume: vc.String(),
		Reason: lock.ReasonRemove,
	}

	return []config.UseLocker{uc, snapUC}, nil
}

func (dc *DaemonConfig) pollRuntime() {
	volumeChan := make(chan *watch.Watch)
	dc.Client.WatchVolumeRuntimes(volumeChan)
	for {
		volWatch := <-volumeChan

		if volWatch.Config == nil {
			continue
		}

		var vol *config.Volume
		var ok bool

		if vol, ok = volWatch.Config.(*config.Volume); !ok {
			logrus.Error(errored.Errorf("Error processing runtime update for volume %q: assertion failed", vol))
			continue
		}

		logrus.Infof("Adjusting runtime parameters for volume %q", vol)
		thisMC, err := dc.API.MountCollection.Get(vol.String())

		if er, ok := err.(*errored.Error); ok && !er.Contains(errors.NotExists) {
			logrus.Errorf("Unknown error processing runtime configuration parameters for volume %q: %v", vol, er)
			continue
		}

		// if we can't look it up, it's possible it was mounted on a different host.
		if err != nil {
			logrus.Errorf("Error retrieving mount information for %q from cache: %v", vol, err)
			continue
		}

		if err := cgroup.ApplyCGroupRateLimit(vol.RuntimeOptions, thisMC); err != nil {
			logrus.Error(errored.Errorf("Error processing runtime update for volume %q", vol).Combine(err))
			continue
		}
	}
}

func (dc *DaemonConfig) createSnapshot(val *config.Volume) {
	logrus.Infof("Snapshotting %q.", val)

	uc := &config.UseSnapshot{
		Volume: val.String(),
		Reason: lock.ReasonSnapshot,
	}

	stopChan, err := lock.NewDriver(dc.Config).AcquireWithTTLRefresh(uc, dc.Global.TTL, dc.Global.Timeout)
	if err != nil {
		logrus.Error(err)
		return
	}

	defer func() { stopChan <- struct{}{} }()

	driver, err := backend.NewSnapshotDriver(val.Backends.Snapshot)
	if err != nil {
		logrus.Errorf("Error establishing driver backend %q; cannot snapshot", val.Backends.Snapshot)
		return
	}

	driverOpts := storage.DriverOptions{
		Volume: storage.Volume{
			Name: val.String(),
			Params: storage.Params{
				"pool": val.DriverOptions["pool"],
			},
		},
		Timeout: dc.Global.Timeout,
	}

	if err := driver.CreateSnapshot(time.Now().String(), driverOpts); err != nil {
		logrus.Errorf("Error creating snapshot for volume %q: %v", val, err)
	}
}

// CreateVolume performs the dirty work of actually constructing a volume.
func CreateVolume(policy *config.Policy, config *config.Volume, timeout time.Duration) (storage.DriverOptions, error) {
	var (
		fscmd string
		ok    bool
	)

	if config.Backends.CRUD == "" {
		logrus.Debugf("Not creating volume %q, backend is unspecified", config)
		return storage.DriverOptions{}, errors.NoActionTaken
	}

	if policy.FileSystems == nil {
		fscmd = defaultFsCmd
	} else {
		fscmd, ok = policy.FileSystems[config.CreateOptions.FileSystem]
		if !ok {
			return storage.DriverOptions{}, errored.Errorf("Invalid filesystem %q", config.CreateOptions.FileSystem)
		}
	}

	actualSize, err := config.CreateOptions.ActualSize()
	if err != nil {
		return storage.DriverOptions{}, err
	}

	driver, err := backend.NewCRUDDriver(config.Backends.CRUD)
	if err != nil {
		return storage.DriverOptions{}, err
	}

	driverOpts := storage.DriverOptions{
		Volume: storage.Volume{
			Name:   config.String(),
			Size:   actualSize,
			Params: config.DriverOptions,
		},
		FSOptions: storage.FSOptions{
			Type:          config.CreateOptions.FileSystem,
			CreateCommand: fscmd,
		},
		Timeout: timeout,
	}

	logrus.Infof("Creating volume %v with size %d", config, actualSize)
	return driverOpts, driver.Create(driverOpts)
}

// ExistsVolume tells if a volume exists. It is *not* suitable for any locking primitive.
func ExistsVolume(config *config.Volume, timeout time.Duration) (bool, error) {
	if config.Backends.CRUD == "" {
		logrus.Debugf("volume %q, backend is unspecified", config)
		return true, errors.NoActionTaken
	}

	driver, err := backend.NewCRUDDriver(config.Backends.CRUD)
	if err != nil {
		return false, err
	}

	driverOpts := storage.DriverOptions{
		Volume: storage.Volume{
			Name:   config.String(),
			Params: config.DriverOptions,
		},
		Timeout: timeout,
	}

	return driver.Exists(driverOpts)
}

// RemoveVolume removes a volume.
func RemoveVolume(config *config.Volume, timeout time.Duration) error {
	if config.Backends.CRUD == "" {
		logrus.Debugf("Not removing volume %q, backend is unspecified", config)
		return errors.NoActionTaken
	}

	driver, err := backend.NewCRUDDriver(config.Backends.CRUD)
	if err != nil {
		return err
	}

	driverOpts := storage.DriverOptions{
		Volume: storage.Volume{
			Name:   config.String(),
			Params: config.DriverOptions,
		},
		Timeout: timeout,
	}

	logrus.Infof("Destroying volume %v", config)

	return driver.Destroy(driverOpts)
}

// this cleans up uses when forcing the removal
func (d *DaemonConfig) removeVolumeUse(lock config.UseLocker, vc *config.Volume) {
	// locks[0] is the usemount lock
	if err := d.Config.RemoveUse(lock, true); err != nil {
		logrus.Warn(errors.RemoveImage.Combine(errored.New(vc.String())).Combine(err))
	}
}