rbd: Add support for rbd ROX PVC mounting

if the PVC access mode is ReadOnlyMany
or single node readonly, mounting the rbd
device path to the staging path as readonly
to avoid the write operation.

If the PVC acccess mode is readonly, mapping
rbd images as readonly.

Signed-off-by: Madhu Rajanna <madhupr007@gmail.com>

internal/csi-common/nodeserver-default.go

@@ -194,3 +194,13 @@ func ConstructMountOptions(mountOptions []string, volCap *csi.VolumeCapability)
 	}
 	return mountOptions
 }
+
+// MountOptionContains checks the opt is present in mountOptions
+func MountOptionContains(mountOptions []string, opt string) bool {
+	for _, mnt := range mountOptions {
+		if mnt == opt {
+			return true
+		}
+	}
+	return false
+}

internal/rbd/nodeserver.go

@@ -204,7 +204,7 @@ func (ns *NodeServer) stageTransaction(ctx context.Context, req *csi.NodeStageVo
 	transaction := stageTransaction{}
 
 	var err error
-
+	var readOnly bool
 	var cr *util.Credentials
 	cr, err = util.NewUserCredentials(req.GetSecrets())
 	if err != nil {
@@ -219,6 +219,13 @@ func (ns *NodeServer) stageTransaction(ctx context.Context, req *csi.NodeStageVo
 	}
 	defer volOptions.Destroy()
 
+	// Allow image to be mounted on multiple nodes if it is ROX
+	if req.VolumeCapability.AccessMode.Mode == csi.VolumeCapability_AccessMode_MULTI_NODE_READER_ONLY {
+		klog.V(3).Infof(util.Log(ctx, "setting disableInUseChecks on rbd volume to: %v"), req.GetVolumeId)
+		volOptions.DisableInUseChecks = true
+		volOptions.readOnly = true
+	}
+
 	// Mapping RBD image
 	var devicePath string
 	devicePath, err = attachRBDImage(ctx, volOptions, cr)
@@ -248,15 +255,16 @@ func (ns *NodeServer) stageTransaction(ctx context.Context, req *csi.NodeStageVo
 	transaction.isStagePathCreated = true
 
 	// nodeStage Path
-	err = ns.mountVolumeToStagePath(ctx, req, staticVol, stagingTargetPath, devicePath)
+	readOnly, err = ns.mountVolumeToStagePath(ctx, req, staticVol, stagingTargetPath, devicePath)
 	if err != nil {
 		return transaction, err
 	}
 	transaction.isMounted = true
 
-	// #nosec - allow anyone to write inside the target path
-	err = os.Chmod(stagingTargetPath, 0777)
-
+	if !readOnly {
+		// #nosec - allow anyone to write inside the target path
+		err = os.Chmod(stagingTargetPath, 0777)
+	}
 	return transaction, err
 }
 
@@ -388,7 +396,8 @@ func getLegacyVolumeName(mountPath string) (string, error) {
 	return volName, nil
 }
 
-func (ns *NodeServer) mountVolumeToStagePath(ctx context.Context, req *csi.NodeStageVolumeRequest, staticVol bool, stagingPath, devicePath string) error {
+func (ns *NodeServer) mountVolumeToStagePath(ctx context.Context, req *csi.NodeStageVolumeRequest, staticVol bool, stagingPath, devicePath string) (bool, error) {
+	readOnly := false
 	fsType := req.GetVolumeCapability().GetMount().GetFsType()
 	diskMounter := &mount.SafeFormatAndMount{Interface: ns.mounter, Exec: utilexec.New()}
 	// rbd images are thin-provisioned and return zeros for unwritten areas.  A freshly created
@@ -404,10 +413,29 @@ func (ns *NodeServer) mountVolumeToStagePath(ctx context.Context, req *csi.NodeS
 	existingFormat, err := diskMounter.GetDiskFormat(devicePath)
 	if err != nil {
 		klog.Errorf(util.Log(ctx, "failed to get disk format for path %s, error: %v"), devicePath, err)
-		return err
+		return readOnly, err
 	}
 
-	if existingFormat == "" && !staticVol {
+	opt := []string{"_netdev"}
+	opt = csicommon.ConstructMountOptions(opt, req.GetVolumeCapability())
+	isBlock := req.GetVolumeCapability().GetBlock() != nil
+	rOnly := "ro"
+
+	if req.VolumeCapability.AccessMode.Mode == csi.VolumeCapability_AccessMode_MULTI_NODE_READER_ONLY ||
+		req.VolumeCapability.AccessMode.Mode == csi.VolumeCapability_AccessMode_SINGLE_NODE_READER_ONLY {
+		if !csicommon.MountOptionContains(opt, rOnly) {
+			opt = append(opt, rOnly)
+		}
+	}
+	if csicommon.MountOptionContains(opt, rOnly) {
+		readOnly = true
+	}
+
+	if fsType == "xfs" {
+		opt = append(opt, "nouuid")
+	}
+
+	if existingFormat == "" && !staticVol && !readOnly {
 		args := []string{}
 		if fsType == "ext4" {
 			args = []string{"-m0", "-Enodiscard,lazy_itable_init=1,lazy_journal_init=1", devicePath}
@@ -417,19 +445,12 @@ func (ns *NodeServer) mountVolumeToStagePath(ctx context.Context, req *csi.NodeS
 		if len(args) > 0 {
 			cmdOut, cmdErr := diskMounter.Exec.Command("mkfs."+fsType, args...).CombinedOutput()
 			if cmdErr != nil {
-				klog.Errorf(util.Log(ctx, "failed to run mkfs error: %v, output: %v"), cmdErr, cmdOut)
-				return cmdErr
+				klog.Errorf(util.Log(ctx, "failed to run mkfs error: %v, output: %v"), cmdErr, string(cmdOut))
+				return readOnly, cmdErr
 			}
 		}
 	}
 
-	opt := []string{"_netdev"}
-	if fsType == "xfs" {
-		opt = append(opt, "nouuid")
-	}
-	opt = csicommon.ConstructMountOptions(opt, req.GetVolumeCapability())
-	isBlock := req.GetVolumeCapability().GetBlock() != nil
-
 	if isBlock {
 		opt = append(opt, "bind")
 		err = diskMounter.Mount(devicePath, stagingPath, fsType, opt)
@@ -445,7 +466,7 @@ func (ns *NodeServer) mountVolumeToStagePath(ctx context.Context, req *csi.NodeS
 			req.GetVolumeId(),
 			err)
 	}
-	return err
+	return readOnly, err
 }
 
 func (ns *NodeServer) mountVolume(ctx context.Context, stagingPath string, req *csi.NodePublishVolumeRequest) error {

internal/rbd/rbd_attach.go

@@ -225,6 +225,9 @@ func createPath(ctx context.Context, volOpt *rbdVolume, cr *util.Credentials) (s
 	// Update options with device type selection
 	mapOptions = append(mapOptions, "--device-type", accessType)
 
+	if volOpt.readOnly {
+		mapOptions = append(mapOptions, "--read-only")
+	}
 	// Execute map
 	output, err := execCommand(rbd, mapOptions)
 	if err != nil {

internal/rbd/rbd_util.go

@@ -100,6 +100,7 @@ type rbdVolume struct {
 	VolSize             int64  `json:"volSize"`
 	DisableInUseChecks  bool   `json:"disableInUseChecks"`
 	Encrypted           bool
+	readOnly            bool
 	KMS                 util.EncryptionKMS
 
 	// conn is a connection to the Ceph cluster obtained from a ConnPool