util: use ClusterConnection.Copy() for re-using connections

Connections are reference counted, so just assigning the connection to
an other object for re-use is not correct. This can cause connections to
be garbage collected while something else is still using it.

Signed-off-by: Niels de Vos <ndevos@redhat.com>

internal/rbd/clone.go

@@ -127,7 +127,7 @@ func (rv *rbdVolume) checkCloneImage(ctx context.Context, parentVol *rbdVolume)
 
 func (rv *rbdVolume) generateTempClone() *rbdVolume {
 	tempClone := rbdVolume{}
-	tempClone.conn = rv.conn
+	tempClone.conn = rv.conn.Copy()
 	// The temp clone image need to have deep flatten feature
 	f := []string{librbd.FeatureNameLayering, librbd.FeatureNameDeepFlatten}
 	tempClone.imageFeatureSet = librbd.FeatureSetFromNames(f)

internal/rbd/rbd_util.go

@@ -496,7 +496,7 @@ func (rv *rbdVolume) getCloneDepth(ctx context.Context) (uint, error) {
 	vol.Pool = rv.Pool
 	vol.Monitors = rv.Monitors
 	vol.RbdImageName = rv.RbdImageName
-	vol.conn = rv.conn
+	vol.conn = rv.conn.Copy()
 
 	err := vol.openIoctx()
 	if err != nil {
@@ -666,7 +666,7 @@ func (rv *rbdVolume) checkImageChainHasFeature(ctx context.Context, feature uint
 	vol.RadosNamespace = rv.RadosNamespace
 	vol.Monitors = rv.Monitors
 	vol.RbdImageName = rv.RbdImageName
-	vol.conn = rv.conn
+	vol.conn = rv.conn.Copy()
 
 	err := vol.openIoctx()
 	if err != nil {

internal/util/conn_pool.go

@@ -168,6 +168,22 @@ func (cp *ConnPool) Get(monitors, user, keyfile string) (*rados.Conn, error) {
 	return conn, nil
 }
 
+// Copy adds an extra reference count to the used ConnEntry and returns the
+// *rados.Conn if it was found.
+func (cp *ConnPool) Copy(conn *rados.Conn) *rados.Conn {
+	cp.lock.Lock()
+	defer cp.lock.Unlock()
+
+	for _, ce := range cp.conns {
+		if ce.conn == conn {
+			ce.get()
+			return ce.conn
+		}
+	}
+
+	return nil
+}
+
 // Put reduces the reference count of the rados.Conn object that was returned with
 // ConnPool.Get().
 func (cp *ConnPool) Put(conn *rados.Conn) {

internal/util/connection.go

@@ -68,6 +68,22 @@ func (cc *ClusterConnection) Destroy() {
 	}
 }
 
+// Copy creates a copy of the ClusterConnection. This is needed when an other
+// object needs to use the existing connection.
+// It is required to call Destroy() once the (copied) connection is not used
+// anymore.
+func (cc *ClusterConnection) Copy() *ClusterConnection {
+	if cc.conn == nil {
+		return nil
+	}
+
+	c := ClusterConnection{}
+	c.discardOnZeroedWriteSameDisabled = cc.discardOnZeroedWriteSameDisabled
+	c.conn = connPool.Copy(cc.conn)
+
+	return &c
+}
+
 func (cc *ClusterConnection) GetIoctx(pool string) (*rados.IOContext, error) {
 	if cc.conn == nil {
 		return nil, errors.New("cluster is not connected yet")