node.go

/*
Copyright 2018 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 service

import (
	"context"
	"errors"
	"fmt"
	"io/ioutil"
	"os"
	"path"
	"path/filepath"
	"strings"

	"github.com/akutz/gofsutil"
	"github.com/container-storage-interface/spec/lib/go/csi"
	csictx "github.com/rexray/gocsi/context"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"
	"k8s.io/klog"

	csipbv1 "github.com/container-storage-interface/spec/lib/go/csi"
	"k8s.io/apimachinery/pkg/api/resource"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	k8svol "k8s.io/kubernetes/pkg/volume"
	"k8s.io/kubernetes/pkg/volume/util/fs"
	cnsvsphere "sigs.k8s.io/vsphere-csi-driver/pkg/common/cns-lib/vsphere"
	cnsconfig "sigs.k8s.io/vsphere-csi-driver/pkg/common/config"
	"sigs.k8s.io/vsphere-csi-driver/pkg/csi/service/common"
	csitypes "sigs.k8s.io/vsphere-csi-driver/pkg/csi/types"
)

const (
	devDiskID   = "/dev/disk/by-id"
	blockPrefix = "wwn-0x"
	dmiDir      = "/sys/class/dmi"
)

func (s *service) NodeStageVolume(
	ctx context.Context,
	req *csi.NodeStageVolumeRequest) (
	*csi.NodeStageVolumeResponse, error) {

	volID := req.GetVolumeId()
	pubCtx := req.GetPublishContext()

	diskID, err := getDiskID(volID, pubCtx)
	if err != nil {
		klog.Errorf("Failed to get diskID. Error: %v", err)
		return nil, err
	}
	klog.V(2).Infof("Checking if volume: %s with diskID: %s is attached", volID, diskID)
	volPath, err := verifyVolumeAttached(diskID)
	if err != nil {
		klog.Errorf("Failed to verify volume attachment. Error: %v", err)
		return nil, err
	}

	// Check that block device looks good
	dev, err := getDevice(volPath)
	if err != nil {
		return nil, status.Errorf(codes.Internal,
			"error getting block device for volume: %s, err: %s",
			volID, err.Error())
	}
	// Check if this is a MountvVolume or BlockVolume
	volCap := req.GetVolumeCapability()
	if _, ok := volCap.GetAccessType().(*csi.VolumeCapability_Block); ok {
		// Volume is a block volume, so skip all the rest
		klog.V(2).Infof("skipping staging for block access type for volume: %s, diskID: %s, device :%s", volID, diskID, dev.RealDev)
		return &csi.NodeStageVolumeResponse{}, nil
	}

	// Extract fs details
	fs, mntFlags, err := ensureMountVol(volCap)
	if err != nil {
		return nil, err
	}

	// Check that target_path is created by CO and is a directory
	target := req.GetStagingTargetPath()
	if err = verifyTargetDir(target); err != nil {
		return nil, err
	}

	accMode := volCap.GetAccessMode().GetMode()
	ro := false
	if accMode == csi.VolumeCapability_AccessMode_SINGLE_NODE_READER_ONLY ||
		accMode == csi.VolumeCapability_AccessMode_MULTI_NODE_READER_ONLY {
		ro = true
	}

	// Get mounts to check if already staged
	mnts, err := gofsutil.GetDevMounts(context.Background(), dev.RealDev)
	if err != nil {
		return nil, status.Errorf(codes.Internal,
			"could not reliably determine existing mount status: %s",
			err.Error())
	}

	attributes := req.VolumeContext
	fsType := attributes[common.AttributeFsType]
	klog.V(2).Infof("fsType from VolumeContext: %s", fsType)
	if fsType == "" {
		// no fsType is set in VolumeContext, use default "ext4"
		fsType = common.DefaultFsType
		klog.V(2).Infof("fsType is not set in VolumeContext, use default type")
	}
	if len(mnts) == 0 {
		// Device isn't mounted anywhere, stage the volume
		if fs == "" {
			fs = fsType
		}

		// If read-only access mode, we don't allow formatting
		if ro {
			mntFlags = append(mntFlags, "ro")
			if err := gofsutil.Mount(ctx, dev.FullPath, target, fs, mntFlags...); err != nil {
				return nil, status.Errorf(codes.Internal,
					"error with mount during staging: %s",
					err.Error())
			}
			return &csi.NodeStageVolumeResponse{}, nil
		}
		if err := gofsutil.FormatAndMount(ctx, dev.FullPath, target, fs, mntFlags...); err != nil {
			return nil, status.Errorf(codes.Internal,
				"error with format and mount during staging: %s",
				err.Error())
		}
		return &csi.NodeStageVolumeResponse{}, nil

	}
	// Device is already mounted. Need to ensure that it is already
	// mounted to the expected staging target, with correct rw/ro perms
	mounted := false
	for _, m := range mnts {
		if m.Path == target {
			mounted = true
			rwo := "rw"
			if ro {
				rwo = "ro"
			}
			if contains(m.Opts, rwo) {
				//TODO make sure that mount options match
				//log.WithFields(f).Debug(
				//	"private mount already in place")
				return &csi.NodeStageVolumeResponse{}, nil
			}
			return nil, status.Error(codes.AlreadyExists,
				"access mode conflicts with existing mount")
		}
	}
	if !mounted {
		return nil, status.Error(codes.Internal,
			"device already in use and mounted elsewhere")
	}

	return nil, nil
}

func (s *service) NodeUnstageVolume(
	ctx context.Context,
	req *csi.NodeUnstageVolumeRequest) (
	*csi.NodeUnstageVolumeResponse, error) {

	volID := req.GetVolumeId()

	target := req.GetStagingTargetPath()
	if err := verifyTargetDir(target); err != nil {
		return nil, err
	}

	// Look up block device mounted to target
	// BlockVolume: Here we are relying on the fact that the CO is required to
	// have created the staging path per the spec, even for BlockVolumes. Even
	// though we don't use the staging path for block, the fact nothing will be
	// mounted still indicates that unstaging is done.
	dev, err := getDevFromMount(target)
	if err != nil {
		return nil, status.Errorf(codes.Internal,
			"error getting block device for volume: %s, err: %s",
			volID, err.Error())
	}

	if dev == nil {
		// Nothing is mounted, so unstaging is already done
		return &csi.NodeUnstageVolumeResponse{}, nil
	}

	klog.V(2).Infof("found device. volID: %q, path: %q, block: %q, target: %q", volID, dev.FullPath, dev.RealDev, target)

	// Get mounts for device
	mnts, err := gofsutil.GetDevMounts(context.Background(), dev.RealDev)
	if err != nil {
		return nil, status.Errorf(codes.Internal,
			"could not reliably determine existing mount status: %s",
			err.Error())
	}

	// device is mounted. Should only be mounted to target
	if len(mnts) > 1 {
		return nil, status.Errorf(codes.Internal,
			"volume: %s appears mounted in multiple places", volID)
	}

	// Since we looked up the block volume from the target path, we assume that
	// the one existing mount is from the block to the target

	// unstage this
	if err := gofsutil.Unmount(context.Background(), target); err != nil {
		return nil, status.Errorf(codes.Internal,
			"Error unmounting target: %s", err.Error())
	}

	return &csi.NodeUnstageVolumeResponse{}, nil
}

func (s *service) NodePublishVolume(
	ctx context.Context,
	req *csi.NodePublishVolumeRequest) (
	*csi.NodePublishVolumeResponse, error) {

	volID := req.GetVolumeId()
	pubCtx := req.GetPublishContext()

	diskID, err := getDiskID(volID, pubCtx)
	if err != nil {
		return nil, err
	}

	klog.V(2).Infof("Checking if volume: %s with diskID: %s is attached", volID, diskID)
	volPath, err := verifyVolumeAttached(diskID)
	if err != nil {
		klog.Errorf("Failed to verify volume attachment. Error: %v", err)
		return nil, err
	}

	// Get underlying block device
	dev, err := getDevice(volPath)
	if err != nil {
		return nil, status.Errorf(codes.Internal,
			"error getting block device for volume: %s, err: %s",
			volID, err.Error())
	}
	// check for Block vs Mount
	volCap := req.GetVolumeCapability()
	if _, ok := volCap.GetAccessType().(*csi.VolumeCapability_Block); ok {
		// bind mount device to target
		return publishBlockVol(ctx, req, dev)
	}

	// Volume must be a mount volume
	return publishMountVol(ctx, req, dev)
}

func (s *service) NodeUnpublishVolume(
	ctx context.Context,
	req *csi.NodeUnpublishVolumeRequest) (
	*csi.NodeUnpublishVolumeResponse, error) {

	volID := req.GetVolumeId()

	target := req.GetTargetPath()
	_, err := os.Stat(target)
	if err != nil {
		if os.IsNotExist(err) {
			// target path does not exist, so we must be Unpublished
			return &csi.NodeUnpublishVolumeResponse{}, nil
		}
		return nil, status.Errorf(codes.Internal,
			"failed to stat target, err: %s", err.Error())
	}

	// Look up block device mounted to target
	dev, err := getDevFromMount(target)
	if err != nil {
		return nil, status.Errorf(codes.Internal,
			"error getting block device for volume: %s, err: %s",
			volID, err.Error())
	}

	if dev == nil {
		// Nothing is mounted, so unpublish is already done. However, we also know
		// that the target path exists, and it is our job to remove it.
		if err := rmpath(target); err != nil {
			return nil, err
		}
		return &csi.NodeUnpublishVolumeResponse{}, nil
	}

	// get mounts
	// Check if device is already unmounted
	mnts, err := gofsutil.GetMounts(ctx)
	if err != nil {
		return nil, status.Errorf(codes.Internal,
			"could not reliably determine existing mount status: %s",
			err.Error())
	}

	for _, m := range mnts {
		if m.Source == dev.RealDev || m.Device == dev.RealDev {
			if m.Path == target {
				if err := gofsutil.Unmount(ctx, target); err != nil {
					return nil, status.Errorf(codes.Internal,
						"Error unmounting target: %s", err.Error())
				}
				if err := rmpath(target); err != nil {
					return nil, err
				}
			}
		}
	}

	return &csi.NodeUnpublishVolumeResponse{}, nil
}

func (s *service) NodeGetVolumeStats(
	ctx context.Context,
	req *csi.NodeGetVolumeStatsRequest) (
	*csi.NodeGetVolumeStatsResponse, error) {

	var err error
	targetPath := req.GetVolumePath()
	if targetPath == "" {
		err = fmt.Errorf("targetpath %v is empty", targetPath)
		return nil, status.Error(codes.InvalidArgument, err.Error())
	}

	dev, err := getDevFromMount(targetPath)
	if err != nil {
		err = fmt.Errorf("unable to get targetpath %v device", targetPath)
		return nil, status.Error(codes.Internal, err.Error())
	}
	if dev == nil {
		err = fmt.Errorf("could not find device mounted on targetpath %v", targetPath)
		return nil, status.Error(codes.Internal, err.Error())
	}

	//TODO Check that the matching device is a vSphere volume, and that the volID matches the mount point

	volMetrics, err := getMetrics(targetPath)
	if err != nil {
		return nil, status.Error(codes.Internal, err.Error())
	}

	available, ok := (*(volMetrics.Available)).AsInt64()
	if !ok {
		klog.Errorf("failed to fetch available bytes")
	}
	capacity, ok := (*(volMetrics.Capacity)).AsInt64()
	if !ok {
		klog.Errorf("failed to fetch capacity bytes")
		return nil, status.Error(codes.Unknown, "failed to fetch capacity bytes")
	}
	used, ok := (*(volMetrics.Used)).AsInt64()
	if !ok {
		klog.Errorf("failed to fetch used bytes")
	}
	inodes, ok := (*(volMetrics.Inodes)).AsInt64()
	if !ok {
		klog.Errorf("failed to fetch available inodes")
		return nil, status.Error(codes.Unknown, "failed to fetch available inodes")

	}
	inodesFree, ok := (*(volMetrics.InodesFree)).AsInt64()
	if !ok {
		klog.Errorf("failed to fetch free inodes")
	}

	inodesUsed, ok := (*(volMetrics.InodesUsed)).AsInt64()
	if !ok {
		klog.Errorf("failed to fetch used inodes")
	}
	return &csi.NodeGetVolumeStatsResponse{
		Usage: []*csi.VolumeUsage{
			{
				Available: available,
				Total:     capacity,
				Used:      used,
				Unit:      csipbv1.VolumeUsage_BYTES,
			},
			{
				Available: inodesFree,
				Total:     inodes,
				Used:      inodesUsed,
				Unit:      csipbv1.VolumeUsage_INODES,
			},
		},
	}, nil
}

//Get volume metrics using k8s fsInfo strategy
func getMetrics(path string) (*k8svol.Metrics, error) {
	if path == "" {
		return nil, fmt.Errorf("No path given")
	}

	available, capacity, usage, inodes, inodesFree, inodesUsed, err := fs.FsInfo(path)
	metrics := &k8svol.Metrics{Time: metav1.Now()}
	if err != nil {
		return nil, err
	}
	metrics.Available = resource.NewQuantity(available, resource.BinarySI)
	metrics.Capacity = resource.NewQuantity(capacity, resource.BinarySI)
	metrics.Used = resource.NewQuantity(usage, resource.BinarySI)
	metrics.Inodes = resource.NewQuantity(inodes, resource.BinarySI)
	metrics.InodesFree = resource.NewQuantity(inodesFree, resource.BinarySI)
	metrics.InodesUsed = resource.NewQuantity(inodesUsed, resource.BinarySI)
	if err != nil {
		return metrics, err
	}

	return metrics, nil
}

func (s *service) NodeGetCapabilities(
	ctx context.Context,
	req *csi.NodeGetCapabilitiesRequest) (
	*csi.NodeGetCapabilitiesResponse, error) {

	return &csi.NodeGetCapabilitiesResponse{
		Capabilities: []*csi.NodeServiceCapability{
			{
				Type: &csi.NodeServiceCapability_Rpc{
					Rpc: &csi.NodeServiceCapability_RPC{
						Type: csi.NodeServiceCapability_RPC_STAGE_UNSTAGE_VOLUME,
					},
				},
			},
			{
				Type: &csi.NodeServiceCapability_Rpc{
					Rpc: &csi.NodeServiceCapability_RPC{
						Type: csi.NodeServiceCapability_RPC_GET_VOLUME_STATS,
					},
				},
			},
		},
	}, nil
}

func (s *service) NodeGetInfo(
	ctx context.Context,
	req *csi.NodeGetInfoRequest) (
	*csi.NodeGetInfoResponse, error) {
	nodeID := os.Getenv("NODE_NAME")
	if nodeID == "" {
		return nil, status.Error(codes.Internal, "ENV NODE_NAME is not set")
	}
	var cfg *cnsconfig.Config
	cfgPath = csictx.Getenv(ctx, cnsconfig.EnvCloudConfig)
	if cfgPath == "" {
		cfgPath = cnsconfig.DefaultCloudConfigPath
	}
	cfg, err := cnsconfig.GetCnsconfig(cfgPath)
	if err != nil {
		if os.IsNotExist(err) {
			klog.V(2).Infof("Config file not provided to node daemonset. Assuming non-topology aware cluster.")
			return &csi.NodeGetInfoResponse{
				NodeId: nodeID,
			}, nil
		}
		klog.Errorf("Failed to read cnsconfig. Error: %v", err)
		return nil, status.Errorf(codes.Internal, err.Error())
	}
	var accessibleTopology map[string]string
	topology := &csi.Topology{}

	if cfg.Labels.Zone != "" && cfg.Labels.Region != "" {
		klog.V(2).Infof("Config file provided to node daemonset with zones and regions. Assuming topology aware cluster.")
		vcenterconfig, err := cnsvsphere.GetVirtualCenterConfig(cfg)
		if err != nil {
			klog.Errorf("Failed to get VirtualCenterConfig from cns config. err=%v", err)
			return nil, status.Errorf(codes.Internal, err.Error())
		}
		vcManager := cnsvsphere.GetVirtualCenterManager()
		vcenter, err := vcManager.RegisterVirtualCenter(vcenterconfig)
		if err != nil {
			klog.Errorf("Failed to register vcenter with virtualCenterManager.")
			return nil, status.Errorf(codes.Internal, err.Error())
		}
		defer vcManager.UnregisterAllVirtualCenters()
		//Connect to vCenter
		err = vcenter.Connect(ctx)
		if err != nil {
			klog.Errorf("Failed to connect to vcenter host: %s. err=%v", vcenter.Config.Host, err)
			return nil, status.Errorf(codes.Internal, err.Error())
		}
		// Get VM UUID
		uuid, err := getSystemUUID()
		if err != nil {
			klog.Errorf("Failed to get system uuid for node VM")
			return nil, status.Errorf(codes.Internal, err.Error())
		}
		klog.V(4).Infof("Successfully retrieved uuid:%s  from the node: %s", uuid, nodeID)
		nodeVM, err := cnsvsphere.GetVirtualMachineByUUID(uuid, false)
		if err != nil || nodeVM == nil {
			klog.Errorf("Failed to get nodeVM for uuid: %s. err: %+v", uuid, err)
			uuid, err = convertUUID(uuid)
			if err != nil {
				klog.Errorf("convertUUID failed with error: %v", err)
				return nil, status.Errorf(codes.Internal, err.Error())
			}
			nodeVM, err = cnsvsphere.GetVirtualMachineByUUID(uuid, false)
			if err != nil || nodeVM == nil {
				klog.Errorf("Failed to get nodeVM for uuid: %s. err: %+v", uuid, err)
				return nil, status.Errorf(codes.Internal, err.Error())
			}
		}
		zone, region, err := nodeVM.GetZoneRegion(ctx, cfg.Labels.Zone, cfg.Labels.Region)
		if err != nil {
			klog.Errorf("Failed to get accessibleTopology for vm: %v, err: %v", nodeVM.Reference(), err)
			return nil, status.Errorf(codes.Internal, err.Error())
		}
		klog.V(4).Infof("zone: [%s], region: [%s], Node VM: [%s]", zone, region, nodeID)
		if zone != "" && region != "" {
			accessibleTopology = make(map[string]string)
			accessibleTopology[csitypes.LabelRegionFailureDomain] = region
			accessibleTopology[csitypes.LabelZoneFailureDomain] = zone
		}
	}
	if len(accessibleTopology) > 0 {
		topology.Segments = accessibleTopology
	}

	return &csi.NodeGetInfoResponse{
		NodeId:             nodeID,
		AccessibleTopology: topology,
	}, nil
}

func publishMountVol(
	ctx context.Context,
	req *csi.NodePublishVolumeRequest,
	dev *Device) (
	*csi.NodePublishVolumeResponse, error) {

	volCap := req.GetVolumeCapability()
	// Extract fs details
	_, mntFlags, err := ensureMountVol(volCap)
	if err != nil {
		return nil, err
	}

	// We are responsible for creating target dir, per spec
	target := req.GetTargetPath()
	_, err = mkdir(target)
	if err != nil {
		return nil, status.Errorf(codes.Internal,
			"Unable to create target dir: %s, err: %v", target, err)
	}

	stagingTarget := req.GetStagingTargetPath()
	if err := verifyTargetDir(stagingTarget); err != nil {
		return nil, err
	}
	ro := req.GetReadonly()
	// get block device mounts
	// Check if device is already mounted
	devMnts, err := getDevMounts(dev)
	if err != nil {
		return nil, status.Errorf(codes.Internal,
			"could not reliably determine existing mount status: %s",
			err.Error())
	}

	// We expect that block device already staged, so there should be at least 1
	// mount already. if it's > 1, it may already be published
	if len(devMnts) > 1 {
		// check if publish is already there
		for _, m := range devMnts {
			if m.Path == target {
				// volume already published to target
				// if mount options look good, do nothing
				rwo := "rw"
				if ro {
					rwo = "ro"
				}
				if !contains(m.Opts, rwo) {
					return nil, status.Error(codes.AlreadyExists,
						"volume previously published with different options")
				}

				// Existing mount satisfies request
				klog.V(3).Infof("volume already published to target. volumePath: %q, device: %q, req: %v", dev.FullPath, dev.RealDev, req)
				return &csi.NodePublishVolumeResponse{}, nil
			}
		}
	} else if len(devMnts) == 0 {
		return nil, status.Errorf(codes.FailedPrecondition,
			"Volume ID: %s does not appear staged to %s", req.GetVolumeId(), stagingTarget)
	}

	// Do the bind mount to publish the volume
	if ro {
		mntFlags = append(mntFlags, "ro")
	}

	if err := gofsutil.BindMount(ctx, stagingTarget, target, mntFlags...); err != nil {
		return nil, status.Errorf(codes.Internal,
			"error publish volume to target path: %s",
			err.Error())
	}

	return &csi.NodePublishVolumeResponse{}, nil
}

func publishBlockVol(
	ctx context.Context,
	req *csi.NodePublishVolumeRequest,
	dev *Device) (
	*csi.NodePublishVolumeResponse, error) {

	// We are responsible for creating target file, per spec
	target := req.GetTargetPath()
	_, err := mkfile(target)
	if err != nil {
		return nil, status.Errorf(codes.Internal,
			"Unable to create target file: %s, err: %v", target, err)
	}

	ro := req.GetReadonly()
	// Read-only is not supported for BlockVolume. Doing a read-only
	// bind mount of the device to the target path does not prevent
	// the underlying block device from being modified, so don't
	// advertise a false sense of security
	if ro {
		return nil, status.Error(codes.InvalidArgument,
			"read only not supported for Block Volume")
	}

	// get block device mounts
	devMnts, err := getDevMounts(dev)
	if err != nil {
		return nil, status.Errorf(codes.Internal,
			"could not reliably determine existing mount status: %s",
			err.Error())
	}

	// check if device is already mounted
	if len(devMnts) == 0 {
		// do the bind mount
		mntFlags := make([]string, 0)
		if err := gofsutil.BindMount(ctx, dev.FullPath, target, mntFlags...); err != nil {
			return nil, status.Errorf(codes.Internal,
				"error publish volume to target path: %s",
				err.Error())
		}
	} else if len(devMnts) == 1 {
		// already mounted, make sure it's what we want
		if devMnts[0].Path != target {
			return nil, status.Error(codes.Internal,
				"device already in use and mounted elsewhere")
		}
		klog.V(3).Infof("volume already published to target. volumePath: %q, device: %q, target: %q", dev.FullPath, dev.RealDev, req.GetTargetPath())
	} else {
		return nil, status.Error(codes.Internal,
			"block volume already mounted in more than one place")
	}
	// existing or new mount satisfies request
	return &csi.NodePublishVolumeResponse{}, nil
}

// Device is a struct for holding details about a block device
type Device struct {
	FullPath string
	Name     string
	RealDev  string
}

// getDevice returns a Device struct with info about the given device, or
// an error if it doesn't exist or is not a block device
func getDevice(path string) (*Device, error) {

	fi, err := os.Lstat(path)
	if err != nil {
		return nil, err
	}

	// eval any symlinks and make sure it points to a device
	d, err := filepath.EvalSymlinks(path)
	if err != nil {
		return nil, err
	}

	ds, err := os.Stat(d)
	if err != nil {
		return nil, err
	}
	dm := ds.Mode()
	if dm&os.ModeDevice == 0 {
		return nil, fmt.Errorf(
			"%s is not a block device", path)
	}

	return &Device{
		Name:     fi.Name(),
		FullPath: path,
		RealDev:  d,
	}, nil
}

// The files parameter is optional for testing purposes
func getDiskPath(id string, files []os.FileInfo) (string, error) {
	var (
		devs []os.FileInfo
		err  error
	)

	if files == nil {
		devs, err = ioutil.ReadDir(devDiskID)
		if err != nil {
			return "", err
		}
	} else {
		devs = files
	}

	targetDisk := blockPrefix + id

	for _, f := range devs {
		if f.Name() == targetDisk {
			return filepath.Join(devDiskID, f.Name()), nil
		}
	}

	return "", nil
}

func contains(list []string, item string) bool {
	for _, x := range list {
		if x == item {
			return true
		}
	}
	return false
}

func verifyVolumeAttached(diskID string) (string, error) {

	// Check that volume is attached
	volPath, err := getDiskPath(diskID, nil)
	if err != nil {
		return "", status.Errorf(codes.Internal,
			"Error trying to read attached disks: %v", err)
	}
	if volPath == "" {
		return "", status.Errorf(codes.NotFound,
			"disk: %s not attached to node", diskID)
	}

	klog.V(2).Infof("found disk. diskID: %q, path: %q", diskID, volPath)
	return volPath, nil
}

func verifyTargetDir(target string) error {
	if target == "" {
		return status.Error(codes.InvalidArgument,
			"target path required")
	}

	tgtStat, err := os.Stat(target)
	if err != nil {
		if os.IsNotExist(err) {
			return status.Errorf(codes.FailedPrecondition,
				"target: %s not pre-created", target)
		}
		return status.Errorf(codes.Internal,
			"failed to stat target, err: %s", err.Error())
	}

	// This check is mandated by the spec, but this would/should fail if the
	// volume has a block accessType. Maybe staging isn't intended to be used
	// with block? That would make sense you cannot share the volume for block.
	if !tgtStat.IsDir() {
		return status.Errorf(codes.FailedPrecondition,
			"existing path: %s is not a directory", target)
	}

	return nil
}

// mkdir creates the directory specified by path if needed.
// return pair is a bool flag of whether dir was created, and an error
func mkdir(path string) (bool, error) {
	st, err := os.Stat(path)
	if err != nil {
		if os.IsNotExist(err) {
			if err := os.Mkdir(path, 0750); err != nil {
				klog.Errorf("Unable to create dir :%q", path)
				return false, err
			}
			klog.V(3).Infof("created directory. Path: %q", path)
			return true, nil
		}
		return false, err
	}
	if !st.IsDir() {
		return false, fmt.Errorf("existing path is not a directory")
	}
	return false, nil
}

// mkfile creates a file specified by the path if needed.
// return pair is a bool flag of whether file was created, and an error
func mkfile(path string) (bool, error) {
	st, err := os.Stat(path)
	if os.IsNotExist(err) {
		file, err := os.OpenFile(path, os.O_CREATE, 0755)
		if err != nil {
			klog.Errorf("Unable to create a file :%q", path)
			return false, err
		}
		file.Close()
		klog.V(3).Infof("created file. Path: %q", path)
		return true, nil
	}
	if st.IsDir() {
		return false, fmt.Errorf("existing path is a directory")
	}
	return false, nil
}

// rmpath removes the given target path, whether it is a file or a directory
// for directories, an error is returned if the dir is not empty
func rmpath(target string) error {
	// target should be empty
	klog.V(3).Infof("removing target path: %q", target)
	if err := os.Remove(target); err != nil {
		return status.Errorf(codes.Internal,
			"Unable to remove target path: %s, err: %v", target, err)
	}
	return nil
}

func ensureMountVol(volCap *csi.VolumeCapability) (string, []string, error) {
	mountVol := volCap.GetMount()
	if mountVol == nil {
		return "", nil, status.Error(codes.InvalidArgument,
			"access type missing")
	}
	fs := mountVol.GetFsType()
	mntFlags := mountVol.GetMountFlags()

	return fs, mntFlags, nil
}

// a wrapper around gofsutil.GetMounts that handles bind mounts
func getDevMounts(
	sysDevice *Device) ([]gofsutil.Info, error) {

	ctx := context.Background()
	devMnts := make([]gofsutil.Info, 0)

	mnts, err := gofsutil.GetMounts(ctx)
	if err != nil {
		return devMnts, err
	}
	for _, m := range mnts {
		if m.Device == sysDevice.RealDev || (m.Device == "devtmpfs" && m.Source == sysDevice.RealDev) {
			devMnts = append(devMnts, m)
		}
	}
	return devMnts, nil
}

func getSystemUUID() (string, error) {
	idb, err := ioutil.ReadFile(path.Join(dmiDir, "id", "product_uuid"))
	if err != nil {
		return "", err
	}
	klog.V(4).Infof("uuid in bytes: %v", idb)
	id := strings.TrimSpace(string(idb))
	klog.V(4).Infof("uuid in string: %s", id)
	return strings.ToLower(id), nil
}

// convertUUID helps convert UUID to vSphere format
//input uuid:    6B8C2042-0DD1-D037-156F-435F999D94C1
//returned uuid: 42208c6b-d10d-37d0-156f-435f999d94c1
func convertUUID(uuid string) (string, error) {
	if len(uuid) != 36 {
		return "", errors.New("uuid length should be 36")
	}
	convertedUUID := fmt.Sprintf("%s%s%s%s-%s%s-%s%s-%s-%s",
		uuid[6:8], uuid[4:6], uuid[2:4], uuid[0:2],
		uuid[11:13], uuid[9:11],
		uuid[16:18], uuid[14:16],
		uuid[19:23],
		uuid[24:36])
	return strings.ToLower(convertedUUID), nil
}

func getDiskID(volID string, pubCtx map[string]string) (string, error) {
	if volID == "" {
		return "", status.Error(codes.InvalidArgument,
			"Volume ID required")
	}
	if _, ok := pubCtx[common.AttributeFirstClassDiskUUID]; !ok {
		return "", status.Errorf(codes.InvalidArgument,
			"Attribute: %s required in publish context",
			common.AttributeFirstClassDiskUUID)
	}
	return pubCtx[common.AttributeFirstClassDiskUUID], nil
}

func getDevFromMount(target string) (*Device, error) {

	// Get list of all mounts on system
	mnts, err := gofsutil.GetMounts(context.Background())
	if err != nil {
		return nil, err
	}

	for _, m := range mnts {
		if m.Path == target {
			// something is mounted to target, get underlying disk
			d := m.Device
			if m.Device == "devtmpfs" {
				d = m.Source
			}
			dev, err := getDevice(d)
			if err != nil {
				return nil, err
			}
			return dev, nil
		}
	}

	// Did not identify a device mounted to target
	return nil, nil
}