Merge pull request #3893 from mheon/readd_volume_locks

Re-add volume locks

9 files changed, 175 insertions, 17 deletions

diff --git a/libpod/boltdb_state.go b/libpod/boltdb_state.go
index 176781f07..1de8d80c9 100644
--- a/libpod/boltdb_state.go
+++ b/libpod/boltdb_state.go
@@ -870,7 +870,7 @@ func (s *BoltState) RewritePodConfig(pod *Pod, newCfg *PodConfig) error {
 
 	newCfgJSON, err := json.Marshal(newCfg)
 	if err != nil {
-		return errors.Wrapf(err, "error marshalling new configuration JSON for container %s", pod.ID())
+		return errors.Wrapf(err, "error marshalling new configuration JSON for pod %s", pod.ID())
 	}
 
 	db, err := s.getDBCon()
@@ -900,6 +900,50 @@ func (s *BoltState) RewritePodConfig(pod *Pod, newCfg *PodConfig) error {
 	return err
 }
 
+// RewriteVolumeConfig rewrites a volume's configuration.
+// WARNING: This function is DANGEROUS. Do not use without reading the full
+// comment on this function in state.go.
+func (s *BoltState) RewriteVolumeConfig(volume *Volume, newCfg *VolumeConfig) error {
+	if !s.valid {
+		return define.ErrDBClosed
+	}
+
+	if !volume.valid {
+		return define.ErrVolumeRemoved
+	}
+
+	newCfgJSON, err := json.Marshal(newCfg)
+	if err != nil {
+		return errors.Wrapf(err, "error marshalling new configuration JSON for volume %q", volume.Name())
+	}
+
+	db, err := s.getDBCon()
+	if err != nil {
+		return err
+	}
+	defer s.deferredCloseDBCon(db)
+
+	err = db.Update(func(tx *bolt.Tx) error {
+		volBkt, err := getVolBucket(tx)
+		if err != nil {
+			return err
+		}
+
+		volDB := volBkt.Bucket([]byte(volume.Name()))
+		if volDB == nil {
+			volume.valid = false
+			return errors.Wrapf(define.ErrNoSuchVolume, "no volume with name %q found in DB", volume.Name())
+		}
+
+		if err := volDB.Put(configKey, newCfgJSON); err != nil {
+			return errors.Wrapf(err, "error updating volume %q config JSON", volume.Name())
+		}
+
+		return nil
+	})
+	return err
+}
+
 // Pod retrieves a pod given its full ID
 func (s *BoltState) Pod(id string) (*Pod, error) {
 	if id == "" {
diff --git a/libpod/boltdb_state_internal.go b/libpod/boltdb_state_internal.go
index 408ef7224..6e4179835 100644
--- a/libpod/boltdb_state_internal.go
+++ b/libpod/boltdb_state_internal.go
@@ -449,6 +449,13 @@ func (s *BoltState) getVolumeFromDB(name []byte, volume *Volume, volBkt *bolt.Bu
 		return errors.Wrapf(err, "error unmarshalling volume %s config from DB", string(name))
 	}
 
+	// Get the lock
+	lock, err := s.runtime.lockManager.RetrieveLock(volume.config.LockID)
+	if err != nil {
+		return errors.Wrapf(err, "error retrieving lock for volume %q", string(name))
+	}
+	volume.lock = lock
+
 	volume.runtime = s.runtime
 	volume.valid = true
 
diff --git a/libpod/in_memory_state.go b/libpod/in_memory_state.go
index 7c4abd25d..a9b735327 100644
--- a/libpod/in_memory_state.go
+++ b/libpod/in_memory_state.go
@@ -425,6 +425,26 @@ func (s *InMemoryState) RewritePodConfig(pod *Pod, newCfg *PodConfig) error {
 	return nil
 }
 
+// RewriteVolumeConfig rewrites a volume's configuration.
+// This function is DANGEROUS, even with in-memory state.
+// Please read the full comment in state.go before using it.
+func (s *InMemoryState) RewriteVolumeConfig(volume *Volume, newCfg *VolumeConfig) error {
+	if !volume.valid {
+		return define.ErrVolumeRemoved
+	}
+
+	// If the volume does not exist, return error
+	stateVol, ok := s.volumes[volume.Name()]
+	if !ok {
+		volume.valid = false
+		return errors.Wrapf(define.ErrNoSuchVolume, "volume with name %q not found in state", volume.Name())
+	}
+
+	stateVol.config = newCfg
+
+	return nil
+}
+
 // Volume retrieves a volume from its full name
 func (s *InMemoryState) Volume(name string) (*Volume, error) {
 	if name == "" {
diff --git a/libpod/runtime_ctr.go b/libpod/runtime_ctr.go
index 92b2faefb..acd317d20 100644
--- a/libpod/runtime_ctr.go
+++ b/libpod/runtime_ctr.go
@@ -253,10 +253,13 @@ func (r *Runtime) setupContainer(ctx context.Context, ctr *Container) (c *Contai
 
 	// Go through named volumes and add them.
 	// If they don't exist they will be created using basic options.
+	// Maintain an array of them - we need to lock them later.
+	ctrNamedVolumes := make([]*Volume, 0, len(ctr.config.NamedVolumes))
 	for _, vol := range ctr.config.NamedVolumes {
 		// Check if it exists already
-		_, err := r.state.Volume(vol.Name)
+		dbVol, err := r.state.Volume(vol.Name)
 		if err == nil {
+			ctrNamedVolumes = append(ctrNamedVolumes, dbVol)
 			// The volume exists, we're good
 			continue
 		} else if errors.Cause(err) != config2.ErrNoSuchVolume {
@@ -275,6 +278,8 @@ func (r *Runtime) setupContainer(ctx context.Context, ctr *Container) (c *Contai
 		if err := ctr.copyWithTarFromImage(vol.Dest, newVol.MountPoint()); err != nil && !os.IsNotExist(err) {
 			return nil, errors.Wrapf(err, "Failed to copy content into new volume mount %q", vol.Name)
 		}
+
+		ctrNamedVolumes = append(ctrNamedVolumes, newVol)
 	}
 
 	if ctr.config.LogPath == "" && ctr.config.LogDriver != JournaldLogging {
@@ -291,6 +296,14 @@ func (r *Runtime) setupContainer(ctx context.Context, ctr *Container) (c *Contai
 		ctr.config.Mounts = append(ctr.config.Mounts, ctr.config.ShmDir)
 	}
 
+	// Lock all named volumes we are adding ourself to, to ensure we can't
+	// use a volume being removed.
+	for _, namedVol := range ctrNamedVolumes {
+		toLock := namedVol
+		toLock.lock.Lock()
+		defer toLock.lock.Unlock()
+	}
+
 	// Add the container to the state
 	// TODO: May be worth looking into recovering from name/ID collisions here
 	if ctr.config.Pod != "" {
diff --git a/libpod/runtime_renumber.go b/libpod/runtime_renumber.go
index 735ffba34..9de2556b2 100644
--- a/libpod/runtime_renumber.go
+++ b/libpod/runtime_renumber.go
@@ -53,6 +53,23 @@ func (r *Runtime) renumberLocks() error {
 			return err
 		}
 	}
+	allVols, err := r.state.AllVolumes()
+	if err != nil {
+		return err
+	}
+	for _, vol := range allVols {
+		lock, err := r.lockManager.AllocateLock()
+		if err != nil {
+			return errors.Wrapf(err, "error allocating lock for volume %s", vol.Name())
+		}
+
+		vol.config.LockID = lock.ID()
+
+		// Write the new lock ID
+		if err := r.state.RewriteVolumeConfig(vol, vol.config); err != nil {
+			return err
+		}
+	}
 
 	r.newSystemEvent(events.Renumber)
 
diff --git a/libpod/runtime_volume.go b/libpod/runtime_volume.go
index d05db936b..512e778a1 100644
--- a/libpod/runtime_volume.go
+++ b/libpod/runtime_volume.go
@@ -36,6 +36,10 @@ func (r *Runtime) RemoveVolume(ctx context.Context, v *Volume, force bool) error
 			return nil
 		}
 	}
+
+	v.lock.Lock()
+	defer v.lock.Unlock()
+
 	return r.removeVolume(ctx, v, force)
 }
 
diff --git a/libpod/runtime_volume_linux.go b/libpod/runtime_volume_linux.go
index 84703787d..70296248c 100644
--- a/libpod/runtime_volume_linux.go
+++ b/libpod/runtime_volume_linux.go
@@ -28,7 +28,7 @@ func (r *Runtime) NewVolume(ctx context.Context, options ...VolumeCreateOption)
 }
 
 // newVolume creates a new empty volume
-func (r *Runtime) newVolume(ctx context.Context, options ...VolumeCreateOption) (*Volume, error) {
+func (r *Runtime) newVolume(ctx context.Context, options ...VolumeCreateOption) (_ *Volume, Err error) {
 	volume, err := newVolume(r)
 	if err != nil {
 		return nil, errors.Wrapf(err, "error creating volume")
@@ -68,6 +68,21 @@ func (r *Runtime) newVolume(ctx context.Context, options ...VolumeCreateOption)
 	}
 	volume.config.MountPoint = fullVolPath
 
+	lock, err := r.lockManager.AllocateLock()
+	if err != nil {
+		return nil, errors.Wrapf(err, "error allocating lock for new volume")
+	}
+	volume.lock = lock
+	volume.config.LockID = volume.lock.ID()
+
+	defer func() {
+		if Err != nil {
+			if err := volume.lock.Free(); err != nil {
+				logrus.Errorf("Error freeing volume lock after failed creation: %v", err)
+			}
+		}
+	}()
+
 	volume.valid = true
 
 	// Add the volume to state
@@ -110,6 +125,8 @@ func (r *Runtime) removeVolume(ctx context.Context, v *Volume, force bool) error
 				return errors.Wrapf(err, "error removing container %s that depends on volume %s", dep, v.Name())
 			}
 
+			logrus.Debugf("Removing container %s (depends on volume %q)", ctr.ID(), v.Name())
+
 			// TODO: do we want to set force here when removing
 			// containers?
 			// I'm inclined to say no, in case someone accidentally
@@ -128,12 +145,24 @@ func (r *Runtime) removeVolume(ctx context.Context, v *Volume, force bool) error
 		return errors.Wrapf(err, "error removing volume %s", v.Name())
 	}
 
-	// Delete the mountpoint path of the volume, that is delete the volume from /var/lib/containers/storage/volumes
+	var removalErr error
+
+	// Free the volume's lock
+	if err := v.lock.Free(); err != nil {
+		removalErr = errors.Wrapf(err, "error freeing lock for volume %s", v.Name())
+	}
+
+	// Delete the mountpoint path of the volume, that is delete the volume
+	// from /var/lib/containers/storage/volumes
 	if err := v.teardownStorage(); err != nil {
-		return errors.Wrapf(err, "error cleaning up volume storage for %q", v.Name())
+		if removalErr == nil {
+			removalErr = errors.Wrapf(err, "error cleaning up volume storage for %q", v.Name())
+		} else {
+			logrus.Errorf("error cleaning up volume storage for volume %q: %v", v.Name(), err)
+		}
 	}
 
 	defer v.newVolumeEvent(events.Remove)
 	logrus.Debugf("Removed volume %s", v.Name())
-	return nil
+	return removalErr
 }
diff --git a/libpod/state.go b/libpod/state.go
index d0ad1a1f8..5d704e69a 100644
--- a/libpod/state.go
+++ b/libpod/state.go
@@ -115,12 +115,20 @@ type State interface {
 	// answer is this: use this only very sparingly, and only if you really
 	// know what you're doing.
 	RewriteContainerConfig(ctr *Container, newCfg *ContainerConfig) error
-	// PLEASE READ THE ABOVE DESCRIPTION BEFORE USING.
+	// PLEASE READ THE DESCRIPTION FOR RewriteContainerConfig BEFORE USING.
 	// This function is identical to RewriteContainerConfig, save for the
 	// fact that it is used with pods instead.
 	// It is subject to the same conditions as RewriteContainerConfig.
 	// Please do not use this unless you know what you're doing.
 	RewritePodConfig(pod *Pod, newCfg *PodConfig) error
+	// PLEASE READ THE DESCRIPTION FOR RewriteContainerConfig BEFORE USING.
+	// This function is identical to RewriteContainerConfig, save for the
+	// fact that it is used with volumes instead.
+	// It is subject to the same conditions as RewriteContainerConfig.
+	// The exception is that volumes do not have IDs, so only volume name
+	// cannot be altered.
+	// Please do not use this unless you know what you're doing.
+	RewriteVolumeConfig(volume *Volume, newCfg *VolumeConfig) error
 
 	// Accepts full ID of pod.
 	// If the pod given is not in the set namespace, an error will be
diff --git a/libpod/volume.go b/libpod/volume.go
index 74126b49b..abfa7b3f4 100644
--- a/libpod/volume.go
+++ b/libpod/volume.go
@@ -2,6 +2,8 @@ package libpod
 
 import (
 	"time"
+
+	"github.com/containers/libpod/libpod/lock"
 )
 
 // Volume is the type used to create named volumes
@@ -11,21 +13,35 @@ type Volume struct {
 
 	valid   bool
 	runtime *Runtime
+	lock    lock.Locker
 }
 
 // VolumeConfig holds the volume's config information
 type VolumeConfig struct {
-	// Name of the volume
+	// Name of the volume.
 	Name string `json:"name"`
-
-	Labels        map[string]string `json:"labels"`
-	Driver        string            `json:"driver"`
-	MountPoint    string            `json:"mountPoint"`
-	CreatedTime   time.Time         `json:"createdAt,omitempty"`
-	Options       map[string]string `json:"options"`
-	IsCtrSpecific bool              `json:"ctrSpecific"`
-	UID           int               `json:"uid"`
-	GID           int               `json:"gid"`
+	// ID of the volume's lock.
+	LockID uint32 `json:"lockID"`
+	// Labels for the volume.
+	Labels map[string]string `json:"labels"`
+	// The volume driver. Empty string or local does not activate a volume
+	// driver, all other volumes will.
+	Driver string `json:"driver"`
+	// The location the volume is mounted at.
+	MountPoint string `json:"mountPoint"`
+	// Time the volume was created.
+	CreatedTime time.Time `json:"createdAt,omitempty"`
+	// Options to pass to the volume driver. For the local driver, this is
+	// a list of mount options. For other drivers, they are passed to the
+	// volume driver handling the volume.
+	Options map[string]string `json:"options"`
+	// Whether this volume was created for a specific container and will be
+	// removed with it.
+	IsCtrSpecific bool `json:"ctrSpecific"`
+	// UID the volume will be created as.
+	UID int `json:"uid"`
+	// GID the volume will be created as.
+	GID int `json:"gid"`
 }
 
 // Name retrieves the volume's name