Add dynamic BackingType detection via VirtualDiskManager

When the disk-backing annotation is not present on a PVC, dynamically
query the backing type from vSphere VirtualDiskManager API and cache
it on the PVC annotation for future attach operations.

Changes:
- Add queryBackingTypeFromVirtualDiskInfo() to query disk type via
  CNS QueryVolume API and VirtualDiskManager.QueryVirtualDiskInfo()
- Add convertDiskTypeToBackingType() to map vSphere disk types
  (thin, preallocated, eagerZeroedThick, etc.) to backing types
- Add patchPVCBackingTypeAnnotation() to persist queried backing type
  on PVC annotation for caching
- Update constructBatchAttachRequest() to query and cache backing type
  when annotation is missing
- Add unit tests for convertDiskTypeToBackingType and
  patchPVCBackingTypeAnnotation functions

Author: divyenpatel

go.mod

@@ -14,6 +14,7 @@ require (
 	github.com/go-co-op/gocron v1.37.0
 	github.com/go-logr/zapr v1.3.0
 	github.com/golang/protobuf v1.5.4
+	github.com/google/go-cmp v0.7.0
 	github.com/google/uuid v1.6.0
 	github.com/hashicorp/go-version v1.6.0
 	github.com/kubernetes-csi/csi-proxy/v2 v2.0.0-alpha.1
@@ -100,7 +101,6 @@ require (
 	github.com/google/btree v1.1.3 // indirect
 	github.com/google/cadvisor v0.52.1 // indirect
 	github.com/google/cel-go v0.26.0 // indirect
-	github.com/google/go-cmp v0.7.0 // indirect
 	github.com/google/pprof v0.0.0-20241029153458-d1b30febd7db // indirect
 	github.com/gregjones/httpcache v0.0.0-20190611155906-901d90724c79 // indirect
 	github.com/grpc-ecosystem/go-grpc-prometheus v1.2.0 // indirect

pkg/common/cns-lib/volume/manager.go

@@ -160,6 +160,9 @@ type Manager interface {
 	UnregisterVolume(ctx context.Context, volumeID string, unregisterDisk bool) (string, error)
 	// SyncVolume returns the aggregated capacity for volumes
 	SyncVolume(ctx context.Context, syncVolumeSpecs []cnstypes.CnsSyncVolumeSpec) (string, error)
+	// QueryBackingTypeFromVirtualDiskInfo queries the backing type of a volume using
+	// VirtualDiskManager's QueryVirtualDiskInfo API.
+	QueryBackingTypeFromVirtualDiskInfo(ctx context.Context, volumeID string) (string, error)
 }
 
 // CnsVolumeInfo hold information related to volume created by CNS.
@@ -3830,3 +3833,81 @@ func (m *defaultManager) unregisterVolume(ctx context.Context, volumeID string,
 	log.Infof("volume %q unregistered successfully", volumeID)
 	return "", nil
 }
+
+// QueryBackingTypeFromVirtualDiskInfo queries the backing type of a volume using
+// VirtualDiskManager's QueryVirtualDiskInfo API.
+// It first queries the volume to get the BackingDiskPath, then uses that path to call
+// QueryVirtualDiskInfo which returns the disk type information.
+func (m *defaultManager) QueryBackingTypeFromVirtualDiskInfo(ctx context.Context,
+	volumeID string) (string, error) {
+	log := logger.GetLogger(ctx)
+
+	// Get the datacenters
+	dcs, err := m.virtualCenter.GetDatacenters(ctx)
+	if err != nil {
+		return "", fmt.Errorf("failed to get datacenters: %w", err)
+	}
+	if len(dcs) == 0 {
+		return "", fmt.Errorf("no datacenters found")
+	}
+
+	// Query volume to get the backing disk path
+	queryFilter := cnstypes.CnsQueryFilter{
+		VolumeIds: []cnstypes.CnsVolumeId{{Id: volumeID}},
+	}
+	querySelection := cnstypes.CnsQuerySelection{
+		Names: []string{string(cnstypes.QuerySelectionNameTypeBackingObjectDetails)},
+	}
+
+	queryResult, err := m.QueryVolumeAsync(ctx, queryFilter, &querySelection)
+	if err != nil {
+		return "", fmt.Errorf("failed to query volume for backing details %s: %w", volumeID, err)
+	}
+	if queryResult == nil || len(queryResult.Volumes) == 0 {
+		return "", fmt.Errorf("no volume found for volumeID %s", volumeID)
+	}
+
+	backingObjectDetails := queryResult.Volumes[0].BackingObjectDetails
+	if backingObjectDetails == nil {
+		return "", fmt.Errorf("backing object details not found for volumeID %s", volumeID)
+	}
+
+	blockBackingDetails, ok := backingObjectDetails.(*cnstypes.CnsBlockBackingDetails)
+	if !ok {
+		return "", fmt.Errorf("backing object details is not of type CnsBlockBackingDetails for volumeID %s", volumeID)
+	}
+
+	backingFilePath := blockBackingDetails.BackingDiskPath
+	if backingFilePath == "" {
+		return "", fmt.Errorf("backing disk path not found for volumeID %s", volumeID)
+	}
+
+	// Get the vim25 client that uses standard vim25 namespace.
+	// This is required because QueryVirtualDiskInfo uses internal vim25 namespace
+	// which doesn't work with the vsan service version used by the main client.
+	vim25Client, err := m.virtualCenter.GetVim25Client(ctx)
+	if err != nil {
+		return "", fmt.Errorf("failed to get vim25 client: %w", err)
+	}
+
+	// Query virtual disk info using the datacenter we already have
+	virtualDiskManager := object.NewVirtualDiskManager(vim25Client)
+	diskInfoList, err := virtualDiskManager.QueryVirtualDiskInfo(ctx, backingFilePath, dcs[0].Datacenter, false)
+	if err != nil {
+		return "", fmt.Errorf("failed to query virtual disk info for %s: %w", backingFilePath, err)
+	}
+	if len(diskInfoList) == 0 {
+		return "", fmt.Errorf("no disk info returned for %s", backingFilePath)
+	}
+
+	diskType := diskInfoList[0].DiskType
+	log.Debugf("Retrieved diskType %s for volumeID %s", diskType, volumeID)
+
+	// Convert diskType to backing type
+	backingType := ConvertDiskTypeToBackingType(diskType)
+	if backingType == "" {
+		return "", fmt.Errorf("unable to find backingType for diskType:%s for the volume %s",
+			diskType, volumeID)
+	}
+	return backingType, nil
+}

pkg/common/cns-lib/volume/manager_mock.go

@@ -199,3 +199,9 @@ func (m MockManager) SyncVolume(ctx context.Context, syncVolumeSpecs []cnstypes.
 	//TODO implement me
 	panic("implement me")
 }
+
+func (m MockManager) QueryBackingTypeFromVirtualDiskInfo(ctx context.Context,
+	volumeID string) (string, error) {
+	//TODO implement me
+	panic("implement me")
+}

pkg/common/cns-lib/volume/util.go

@@ -632,3 +632,32 @@ func IsCnsVolumeAlreadyExistsFault(ctx context.Context, faultType string) bool {
 	log.Infof("Checking fault type: %q is vim.fault.CnsVolumeAlreadyExistsFault", faultType)
 	return faultType == "vim.fault.CnsVolumeAlreadyExistsFault"
 }
+
+// ConvertDiskTypeToBackingType converts the diskType returned by QueryVirtualDiskInfo
+// to the appropriate CnsVolumeBackingType string used for batch attach operations.
+// The returned values correspond to VirtualDevice.FileBackingInfo subclasses as defined in
+// github.com/vmware/govmomi/cns/types (CnsVolumeBackingType constants).
+func ConvertDiskTypeToBackingType(diskType string) string {
+	switch diskType {
+	case "thin", "preallocated", "thick", "eagerZeroedThick", "thick2Gb", "flatMonolithic":
+		// All flat/thick disk types use FlatVer2BackingInfo
+		// thin -> FlatVer2BackingInfo (thinProvisioned=true)
+		// preallocated/thick -> FlatVer2BackingInfo (thinProvisioned=false, eagerlyScrub=false)
+		// eagerZeroedThick -> FlatVer2BackingInfo (thinProvisioned=false, eagerlyScrub=true)
+		// thick2Gb/flatMonolithic -> FlatVer2BackingInfo (split variations)
+		return string(cnstypes.CnsVolumeBackingTypeFlatVer2BackingInfo)
+	case "sparse2Gb", "sparseMonolithic", "delta", "vmfsSparse":
+		// sparse types -> SparseVer2BackingInfo
+		return string(cnstypes.CnsVolumeBackingTypeSparseVer2BackingInfo)
+	case "seSparse":
+		// seSparse -> SeSparseBackingInfo
+		return string(cnstypes.CnsVolumeBackingTypeSeSparseBackingInfo)
+	case "rdm", "rdmp":
+		// rdm -> RawDiskMappingVer1BackingInfo (compatibilityMode="virtualMode")
+		// rdmp -> RawDiskMappingVer1BackingInfo (compatibilityMode="physicalMode")
+		return string(cnstypes.CnsVolumeBackingTypeRawDiskMappingVer1BackingInfo)
+	default:
+		// Unknown disk type, return empty string
+		return ""
+	}
+}

pkg/common/cns-lib/volume/util_test.go

@@ -0,0 +1,114 @@
+/*
+Copyright 2025 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package volume
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestConvertDiskTypeToBackingType(t *testing.T) {
+	tests := []struct {
+		name     string
+		diskType string
+		want     string
+	}{
+		{
+			name:     "thin disk type",
+			diskType: "thin",
+			want:     "FlatVer2BackingInfo",
+		},
+		{
+			name:     "preallocated disk type",
+			diskType: "preallocated",
+			want:     "FlatVer2BackingInfo",
+		},
+		{
+			name:     "thick disk type",
+			diskType: "thick",
+			want:     "FlatVer2BackingInfo",
+		},
+		{
+			name:     "eagerZeroedThick disk type",
+			diskType: "eagerZeroedThick",
+			want:     "FlatVer2BackingInfo",
+		},
+		{
+			name:     "sparse2Gb disk type",
+			diskType: "sparse2Gb",
+			want:     "SparseVer2BackingInfo",
+		},
+		{
+			name:     "sparseMonolithic disk type",
+			diskType: "sparseMonolithic",
+			want:     "SparseVer2BackingInfo",
+		},
+		{
+			name:     "delta disk type",
+			diskType: "delta",
+			want:     "SparseVer2BackingInfo",
+		},
+		{
+			name:     "vmfsSparse disk type",
+			diskType: "vmfsSparse",
+			want:     "SparseVer2BackingInfo",
+		},
+		{
+			name:     "thick2Gb disk type",
+			diskType: "thick2Gb",
+			want:     "FlatVer2BackingInfo",
+		},
+		{
+			name:     "flatMonolithic disk type",
+			diskType: "flatMonolithic",
+			want:     "FlatVer2BackingInfo",
+		},
+		{
+			name:     "seSparse disk type",
+			diskType: "seSparse",
+			want:     "SeSparseBackingInfo",
+		},
+		{
+			name:     "rdm disk type",
+			diskType: "rdm",
+			want:     "RawDiskMappingVer1BackingInfo",
+		},
+		{
+			name:     "rdmp disk type",
+			diskType: "rdmp",
+			want:     "RawDiskMappingVer1BackingInfo",
+		},
+		{
+			name:     "unknown disk type",
+			diskType: "unknown",
+			want:     "",
+		},
+		{
+			name:     "empty disk type",
+			diskType: "",
+			want:     "",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := ConvertDiskTypeToBackingType(tt.diskType)
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}

pkg/common/cns-lib/vsphere/virtualcenter.go

@@ -76,6 +76,11 @@ type VirtualCenter struct {
 	VsanClient *vsan.Client
 	// VslmClient represents the Vslm client instance.
 	VslmClient *vslm.Client
+	// Vim25Client is a vim25.Client that uses the standard vim25 namespace.
+	// This is needed for APIs like VirtualDiskManager.QueryVirtualDiskInfo that
+	// use internal vim25 namespaces and don't work with the vsan service version.
+	// It shares the same http.Transport as the main Client but uses vim25.Path and vim25.Namespace.
+	Vim25Client *vim25.Client
 	// ClientMutex is used for exclusive connection creation.
 	ClientMutex *sync.Mutex
 }
@@ -386,9 +391,50 @@ func (vc *VirtualCenter) connect(ctx context.Context) error {
 		}
 		vc.VsanClient.RoundTripper = &MetricRoundTripper{"vsan", vc.VsanClient.RoundTripper}
 	}
+	// Recreate Vim25Client if created using timed out VC Client.
+	if vc.Vim25Client != nil {
+		vc.Vim25Client = vc.newVim25Client()
+	}
 	return nil
 }
 
+// newVim25Client creates a vim25.Client that uses the standard vim25 namespace.
+// This is needed for APIs like VirtualDiskManager.QueryVirtualDiskInfo that use
+// internal vim25 namespaces and don't work with the vsan service version.
+func (vc *VirtualCenter) newVim25Client() *vim25.Client {
+	soapClient := vc.Client.Client.Client
+	vimSoapClient := soapClient.NewServiceClient(vim25.Path, vim25.Namespace)
+	vimSoapClient.Version = vc.Client.Client.ServiceContent.About.ApiVersion
+	return &vim25.Client{
+		Client:         vimSoapClient,
+		ServiceContent: vc.Client.Client.ServiceContent,
+		RoundTripper:   vimSoapClient,
+	}
+}
+
+// GetVim25Client returns a vim25.Client that uses the standard vim25 namespace.
+// This client is needed for APIs like VirtualDiskManager.QueryVirtualDiskInfo that
+// use internal vim25 namespaces and don't work with the vsan service version.
+// The client is created lazily on first call and reused for subsequent calls.
+// It shares the same http.Transport as the main Client.
+func (vc *VirtualCenter) GetVim25Client(ctx context.Context) (*vim25.Client, error) {
+	log := logger.GetLogger(ctx)
+
+	// Ensure connection is established
+	if err := vc.Connect(ctx); err != nil {
+		return nil, err
+	}
+
+	vc.ClientMutex.Lock()
+	defer vc.ClientMutex.Unlock()
+
+	if vc.Vim25Client == nil {
+		log.Info("Creating Vim25Client for standard vim25 namespace operations")
+		vc.Vim25Client = vc.newVim25Client()
+	}
+	return vc.Vim25Client, nil
+}
+
 // ReadVCConfigs will ensure we are always reading the latest config
 // before attempting to create a new govmomi client.
 // It works in case of both vanilla (including multi-vc) and wcp

pkg/common/unittestcommon/types.go

@@ -224,3 +224,8 @@ func (m *MockVolumeManager) SyncVolume(ctx context.Context,
 	syncVolumeSpecs []cnstypes.CnsSyncVolumeSpec) (string, error) {
 	return "", nil
 }
+
+func (m *MockVolumeManager) QueryBackingTypeFromVirtualDiskInfo(ctx context.Context,
+	volumeID string) (string, error) {
+	return "", nil
+}

pkg/csi/service/common/vsphereutil_test.go

@@ -131,6 +131,12 @@ func (m *mockVolumeManager) SyncVolume(ctx context.Context,
 	syncVolumeSpecs []cnstypes.CnsSyncVolumeSpec) (string, error) {
 	return "", nil
 }
+
+func (m *mockVolumeManager) QueryBackingTypeFromVirtualDiskInfo(ctx context.Context,
+	volumeID string) (string, error) {
+	return "", nil
+}
+
 func TestQueryVolumeSnapshotsByVolumeIDWithQuerySnapshotsCnsVolumeNotFoundFault(t *testing.T) {
 	// Skip test on ARM64 due to gomonkey limitations
 	if runtime.GOARCH == "arm64" {

pkg/syncer/cnsoperator/controller/cnsnodevmbatchattachment/cnsnodevmbatchattachment_controller.go

@@ -538,7 +538,7 @@ func (r *Reconciler) processBatchAttach(ctx context.Context, k8sClient kubernete
 
 	// Construct batch attach request
 	pvcsInAttachList, volumeIdsInAttachList, batchAttachRequest, err := constructBatchAttachRequest(ctx,
-		volumesToAttach, instance)
+		volumesToAttach, instance, r.volumeManager, k8sClient)
 	if err != nil {
 		log.Errorf("failed to construct batch attach request. Err: %s", err)
 		return err