Fix hyperdisk attach limits

Reserve 1 attachment for the root / OS disk when reporting nr. of
attachable hyperdisks.

Author: jsafrane

pkg/common/constants.go

@@ -39,10 +39,10 @@ var Gen4MachineHyperdiskAttachLimitMap = []struct {
 	max   int64
 	value int64
 }{
-	{max: 4, value: 16},
-	{max: 8, value: 24},
-	{max: 16, value: 32},
-	{max: 32, value: 48},
-	{max: 64, value: 64},
-	{max: 1024, value: 128},
+	{max: 4, value: 15},
+	{max: 8, value: 23},
+	{max: 16, value: 31},
+	{max: 32, value: 49},
+	{max: 64, value: 63},
+	{max: 1024, value: 127},
 }

pkg/gce-pd-csi-driver/node.go

@@ -93,9 +93,9 @@ const (
 	volumeLimitSmall int64 = 15
 	volumeLimitBig   int64 = 127
 	// doc https://cloud.google.com/compute/docs/memory-optimized-machines#x4_disks
-	x4HyperdiskLimit int64 = 40
+	x4HyperdiskLimit int64 = 39
 	// doc https://cloud.google.com/compute/docs/accelerator-optimized-machines#a4-disks
-	a4HyperdiskLimit     int64 = 128
+	a4HyperdiskLimit     int64 = 127
 	defaultLinuxFsType         = "ext4"
 	defaultWindowsFsType       = "ntfs"
 	fsTypeExt3                 = "ext3"

pkg/gce-pd-csi-driver/node_test.go

@@ -257,27 +257,27 @@ func TestNodeGetVolumeLimits(t *testing.T) {
 		{
 			name:           "c4-standard-192",
 			machineType:    "c4-standard-192",
-			expVolumeLimit: 128,
+			expVolumeLimit: 127,
 		},
 		{
 			name:           "c4-standard-48",
 			machineType:    "c4-standard-48",
-			expVolumeLimit: 64,
+			expVolumeLimit: 63,
 		},
 		{
 			name:           "c4a-standard-4",
 			machineType:    "c4a-standard-4",
-			expVolumeLimit: 16,
+			expVolumeLimit: 15,
 		},
 		{
 			name:           "n4-standard-16",
 			machineType:    "n4-standard-16",
-			expVolumeLimit: 32,
+			expVolumeLimit: 31,
 		},
 		{
 			name:           "n4-highcpu-4",
 			machineType:    "n4-highcpu-4",
-			expVolumeLimit: 16,
+			expVolumeLimit: 15,
 		},
 		{
 			name:           "invalid gen4 machine type",