Add I/O priority

Signed-off-by: utam0k <k0ma@utam0k.jp>

libcontainer/configs/config.go

@@ -222,6 +222,9 @@ type Config struct {
 
 	// Personality contains configuration for the Linux personality syscall.
 	Personality *LinuxPersonality `json:"personality,omitempty"`
+
+	// IOPriority is the container's I/O priority.
+	IOPriority *IOPriority `json:"io_priority,omitempty"`
 }
 
 // Scheduler is based on the Linux sched_setattr(2) syscall.
@@ -283,6 +286,14 @@ 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 (
 	HookName string
 	HookList []Hook

libcontainer/configs/validate/validator.go

@@ -32,6 +32,7 @@ func Validate(config *configs.Config) error {
 		rootlessEUIDCheck,
 		mountsStrict,
 		scheduler,
+		ioPriority,
 	}
 	for _, c := range checks {
 		if err := c(config); err != nil {
@@ -396,3 +397,14 @@ func scheduler(config *configs.Config) error {
 	}
 	return nil
 }
+
+func ioPriority(config *configs.Config) error {
+	if config.IOPriority == nil {
+		return nil
+	}
+	priority := config.IOPriority.Priority
+	if priority < 0 || priority > 7 {
+		return fmt.Errorf("invalid ioPriority.Priority: %d", priority)
+	}
+	return nil
+}

libcontainer/configs/validate/validator_test.go

@@ -842,3 +842,32 @@ func TestValidateScheduler(t *testing.T) {
 		}
 	}
 }
+
+func TestValidateIOPriority(t *testing.T) {
+	testCases := []struct {
+		isErr    bool
+		priority int
+	}{
+		{isErr: false, priority: 0},
+		{isErr: false, priority: 7},
+		{isErr: true, priority: -1},
+	}
+
+	for _, tc := range testCases {
+		ioPriroty := configs.IOPriority{
+			Priority: tc.priority,
+		}
+		config := &configs.Config{
+			Rootfs:     "/var",
+			IOPriority: &ioPriroty,
+		}
+
+		err := Validate(config)
+		if tc.isErr && err == nil {
+			t.Errorf("iopriority: %d, expected error, got nil", tc.priority)
+		}
+		if !tc.isErr && err != nil {
+			t.Errorf("iopriority: %d, expected nil, got error %v", tc.priority, err)
+		}
+	}
+}