scheduler: run Unreserve if Reserve fails

If a reserve plugin's Reserve method returns an error, there could be
previously allocated resources from successfully completed reserve
plugins that must be unallocated by the corresponding Unreserve
operation. Since Unreserve operations are idempotent, this patch runs
the Unreserve operation of ALL reserve plugins when a Reserve operation
fails.

test/integration/scheduler/framework_test.go

@@ -269,6 +269,7 @@ func (rp *ReservePlugin) Unreserve(ctx context.Context, state *framework.CycleSt
 func (rp *ReservePlugin) reset() {
 	rp.numReserveCalled = 0
 	rp.numUnreserveCalled = 0
+	rp.failReserve = false
 }
 
 // Name returns name of the plugin.
@@ -1006,22 +1007,31 @@ func TestReservePluginUnreserve(t *testing.T) {
 	defer testutils.CleanupTest(t, testCtx)
 
 	tests := []struct {
-		name        string
-		preBindFail bool
+		name             string
+		failReserve      bool
+		failReserveIndex int
+		failPreBind      bool
 	}{
 		{
-			name:        "fail preBind",
-			preBindFail: true,
+			name:             "fail reserve",
+			failReserve:      true,
+			failReserveIndex: 1,
 		},
 		{
-			name:        "pass preBind",
-			preBindFail: false,
+			name:        "fail preBind",
+			failPreBind: true,
+		},
+		{
+			name: "pass everything",
 		},
 	}
 
 	for _, test := range tests {
 		t.Run(test.name, func(t *testing.T) {
-			preBindPlugin.failPreBind = test.preBindFail
+			preBindPlugin.failPreBind = test.failPreBind
+			if test.failReserve {
+				reservePlugins[test.failReserveIndex].failReserve = true
+			}
 			// Create a best effort pod.
 			pod, err := createPausePod(testCtx.ClientSet,
 				initPausePod(&pausePodConfig{Name: "test-pod", Namespace: testCtx.NS.Name}))
@@ -1029,7 +1039,7 @@ func TestReservePluginUnreserve(t *testing.T) {
 				t.Errorf("Error while creating a test pod: %v", err)
 			}
 
-			if test.preBindFail {
+			if test.failPreBind || test.failReserve {
 				if err = wait.Poll(10*time.Millisecond, 30*time.Second, podSchedulingError(testCtx.ClientSet, pod.Namespace, pod.Name)); err != nil {
 					t.Errorf("Expected a scheduling error, but didn't get it: %v", err)
 				}