fix: add VolumeStats cache to avoid massive statfs calls

cmd/nfsplugin/main.go

@@ -26,12 +26,13 @@ import (
 )
 
 var (
-	endpoint              = flag.String("endpoint", "unix://tmp/csi.sock", "CSI endpoint")
-	nodeID                = flag.String("nodeid", "", "node id")
-	mountPermissions      = flag.Uint64("mount-permissions", 0, "mounted folder permissions")
-	driverName            = flag.String("drivername", nfs.DefaultDriverName, "name of the driver")
-	workingMountDir       = flag.String("working-mount-dir", "/tmp", "working directory for provisioner to mount nfs shares temporarily")
-	defaultOnDeletePolicy = flag.String("default-ondelete-policy", "", "default policy for deleting subdirectory when deleting a volume")
+	endpoint                     = flag.String("endpoint", "unix://tmp/csi.sock", "CSI endpoint")
+	nodeID                       = flag.String("nodeid", "", "node id")
+	mountPermissions             = flag.Uint64("mount-permissions", 0, "mounted folder permissions")
+	driverName                   = flag.String("drivername", nfs.DefaultDriverName, "name of the driver")
+	workingMountDir              = flag.String("working-mount-dir", "/tmp", "working directory for provisioner to mount nfs shares temporarily")
+	defaultOnDeletePolicy        = flag.String("default-ondelete-policy", "", "default policy for deleting subdirectory when deleting a volume")
+	volStatsCacheExpireInMinutes = flag.Int("vol-stats-cache-expire-in-minutes", 10, "The cache expire time in minutes for volume stats cache")
 )
 
 func main() {
@@ -48,12 +49,13 @@ func main() {
 
 func handle() {
 	driverOptions := nfs.DriverOptions{
-		NodeID:                *nodeID,
-		DriverName:            *driverName,
-		Endpoint:              *endpoint,
-		MountPermissions:      *mountPermissions,
-		WorkingMountDir:       *workingMountDir,
-		DefaultOnDeletePolicy: *defaultOnDeletePolicy,
+		NodeID:                       *nodeID,
+		DriverName:                   *driverName,
+		Endpoint:                     *endpoint,
+		MountPermissions:             *mountPermissions,
+		WorkingMountDir:              *workingMountDir,
+		DefaultOnDeletePolicy:        *defaultOnDeletePolicy,
+		VolStatsCacheExpireInMinutes: *volStatsCacheExpireInMinutes,
 	}
 	d := nfs.NewDriver(&driverOptions)
 	d.Run(false)

pkg/nfs/nfs.go

@@ -19,6 +19,7 @@ package nfs
 import (
 	"runtime"
 	"strings"
+	"time"
 
 	"github.com/container-storage-interface/spec/lib/go/csi"
 	"k8s.io/klog/v2"
@@ -29,12 +30,13 @@ import (
 
 // DriverOptions defines driver parameters specified in driver deployment
 type DriverOptions struct {
-	NodeID                string
-	DriverName            string
-	Endpoint              string
-	MountPermissions      uint64
-	WorkingMountDir       string
-	DefaultOnDeletePolicy string
+	NodeID                       string
+	DriverName                   string
+	Endpoint                     string
+	MountPermissions             uint64
+	WorkingMountDir              string
+	DefaultOnDeletePolicy        string
+	VolStatsCacheExpireInMinutes int
 }
 
 type Driver struct {
@@ -53,7 +55,8 @@ type Driver struct {
 	volumeLocks *VolumeLocks
 
 	// a timed cache storing volume stats <volumeID, volumeStats>
-	volStatsCache azcache.Resource
+	volStatsCache                azcache.Resource
+	volStatsCacheExpireInMinutes int
 }
 
 const (
@@ -81,12 +84,13 @@ func NewDriver(options *DriverOptions) *Driver {
 	klog.V(2).Infof("Driver: %v version: %v", options.DriverName, driverVersion)
 
 	n := &Driver{
-		name:             options.DriverName,
-		version:          driverVersion,
-		nodeID:           options.NodeID,
-		endpoint:         options.Endpoint,
-		mountPermissions: options.MountPermissions,
-		workingMountDir:  options.WorkingMountDir,
+		name:                         options.DriverName,
+		version:                      driverVersion,
+		nodeID:                       options.NodeID,
+		endpoint:                     options.Endpoint,
+		mountPermissions:             options.MountPermissions,
+		workingMountDir:              options.WorkingMountDir,
+		volStatsCacheExpireInMinutes: options.VolStatsCacheExpireInMinutes,
 	}
 
 	n.AddControllerServiceCapabilities([]csi.ControllerServiceCapability_RPC_Type{
@@ -102,6 +106,16 @@ func NewDriver(options *DriverOptions) *Driver {
 		csi.NodeServiceCapability_RPC_UNKNOWN,
 	})
 	n.volumeLocks = NewVolumeLocks()
+
+	if options.VolStatsCacheExpireInMinutes <= 0 {
+		options.VolStatsCacheExpireInMinutes = 10 // default expire in 10 minutes
+	}
+
+	var err error
+	getter := func(key string) (interface{}, error) { return nil, nil }
+	if n.volStatsCache, err = azcache.NewTimedCache(time.Duration(options.VolStatsCacheExpireInMinutes)*time.Minute, getter, false); err != nil {
+		klog.Fatalf("%v", err)
+	}
 	return n
 }
 

pkg/nfs/nfs_test.go

@@ -20,9 +20,11 @@ import (
 	"os"
 	"path/filepath"
 	"testing"
+	"time"
 
 	"github.com/container-storage-interface/spec/lib/go/csi"
 	"github.com/stretchr/testify/assert"
+	azcache "sigs.k8s.io/cloud-provider-azure/pkg/cache"
 )
 
 const (
@@ -52,6 +54,8 @@ func NewEmptyDriver(emptyField string) *Driver {
 		}
 	}
 	d.volumeLocks = NewVolumeLocks()
+	getter := func(key string) (interface{}, error) { return nil, nil }
+	d.volStatsCache, _ = azcache.NewTimedCache(time.Minute, getter, false)
 	return d
 }
 

pkg/nfs/nodeserver.go

@@ -30,6 +30,8 @@ import (
 	"k8s.io/klog/v2"
 	"k8s.io/kubernetes/pkg/volume"
 	mount "k8s.io/mount-utils"
+
+	azcache "sigs.k8s.io/cloud-provider-azure/pkg/cache"
 )
 
 // NodeServer driver
@@ -195,6 +197,17 @@ func (ns *NodeServer) NodeGetVolumeStats(_ context.Context, req *csi.NodeGetVolu
 		return nil, status.Error(codes.InvalidArgument, "NodeGetVolumeStats volume path was empty")
 	}
 
+	// check if the volume stats is cached
+	cache, err := ns.Driver.volStatsCache.Get(req.VolumeId, azcache.CacheReadTypeDefault)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, err.Error())
+	}
+	if cache != nil {
+		resp := cache.(csi.NodeGetVolumeStatsResponse)
+		klog.V(6).Infof("NodeGetVolumeStats: volume stats for volume %s path %s is cached", req.VolumeId, req.VolumePath)
+		return &resp, nil
+	}
+
 	if _, err := os.Lstat(req.VolumePath); err != nil {
 		if os.IsNotExist(err) {
 			return nil, status.Errorf(codes.NotFound, "path %s does not exist", req.VolumePath)
@@ -233,7 +246,7 @@ func (ns *NodeServer) NodeGetVolumeStats(_ context.Context, req *csi.NodeGetVolu
 		return nil, status.Errorf(codes.Internal, "failed to transform disk inodes used(%v)", volumeMetrics.InodesUsed)
 	}
 
-	return &csi.NodeGetVolumeStatsResponse{
+	resp := csi.NodeGetVolumeStatsResponse{
 		Usage: []*csi.VolumeUsage{
 			{
 				Unit:      csi.VolumeUsage_BYTES,
@@ -248,7 +261,11 @@ func (ns *NodeServer) NodeGetVolumeStats(_ context.Context, req *csi.NodeGetVolu
 				Used:      inodesUsed,
 			},
 		},
-	}, nil
+	}
+
+	// cache the volume stats per volume
+	ns.Driver.volStatsCache.Set(req.VolumeId, &resp)
+	return &resp, err
 }
 
 // NodeUnstageVolume unstage volume