libct/configs: rm IOPrioClassMapping

This is an internal implementation detail and should not be either
public or visible.

Amend setIOPriority to do own class conversion.

Fixes: bfbd0305 ("Add I/O priority")
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

libcontainer/configs/config.go

@@ -286,12 +286,6 @@ func ToSchedAttr(scheduler *Scheduler) (*unix.SchedAttr, error) {
 	}, nil
 }
 
-var IOPrioClassMapping = map[specs.IOPriorityClass]int{
-	specs.IOPRIO_CLASS_RT:   1,
-	specs.IOPRIO_CLASS_BE:   2,
-	specs.IOPRIO_CLASS_IDLE: 3,
-}
-
 type IOPriority = specs.LinuxIOPriority
 
 type (

libcontainer/init_linux.go

@@ -685,8 +685,15 @@ func setupIOPriority(config *configs.Config) error {
 	if ioprio == nil {
 		return nil
 	}
-	class, ok := configs.IOPrioClassMapping[ioprio.Class]
-	if !ok {
+	class := 0
+	switch ioprio.Class {
+	case specs.IOPRIO_CLASS_RT:
+		class = 1
+	case specs.IOPRIO_CLASS_BE:
+		class = 2
+	case specs.IOPRIO_CLASS_IDLE:
+		class = 3
+	default:
 		return fmt.Errorf("invalid io priority class: %s", ioprio.Class)
 	}