util: make inode metrics optional in FilesystemNodeGetVolumeStats()

CephFS does not have a concept of "free inodes", inodes get allocated
on-demand in the filesystem.

This confuses alerting managers that expect a (high) number of free
inodes, and warnings get produced if the number of free inodes is not
high enough. This causes alerts to always get reported for CephFS.

To prevent the false-positive alerts from happening, the
NodeGetVolumeStats procedure for CephFS (and CephNFS) will not contain
inodes in the reply anymore.

See-also: https://bugzilla.redhat.com/2128263
Signed-off-by: Niels de Vos <ndevos@redhat.com>

internal/cephfs/nodeserver.go

@@ -637,7 +637,7 @@ func (ns *NodeServer) NodeGetVolumeStats(
 	}
 
 	if stat.Mode().IsDir() {
-		return csicommon.FilesystemNodeGetVolumeStats(ctx, ns.Mounter, targetPath)
+		return csicommon.FilesystemNodeGetVolumeStats(ctx, ns.Mounter, targetPath, false)
 	}
 
 	return nil, status.Errorf(codes.InvalidArgument, "targetpath %q is not a directory or device", targetPath)

internal/csi-common/utils.go

@@ -241,6 +241,7 @@ func FilesystemNodeGetVolumeStats(
 	ctx context.Context,
 	mounter mount.Interface,
 	targetPath string,
+	includeInodes bool,
 ) (*csi.NodeGetVolumeStatsResponse, error) {
 	isMnt, err := util.IsMountPoint(mounter, targetPath)
 	if err != nil {
@@ -274,23 +275,8 @@ func FilesystemNodeGetVolumeStats(
 	if !ok {
 		log.ErrorLog(ctx, "failed to fetch used bytes")
 	}
-	inodes, ok := (*(volMetrics.Inodes)).AsInt64()
-	if !ok {
-		log.ErrorLog(ctx, "failed to fetch available inodes")
 
-		return nil, status.Error(codes.Unknown, "failed to fetch available inodes")
+	res := &csi.NodeGetVolumeStatsResponse{
-	}
-	inodesFree, ok := (*(volMetrics.InodesFree)).AsInt64()
-	if !ok {
-		log.ErrorLog(ctx, "failed to fetch free inodes")
-	}
-
-	inodesUsed, ok := (*(volMetrics.InodesUsed)).AsInt64()
-	if !ok {
-		log.ErrorLog(ctx, "failed to fetch used inodes")
-	}
-
-	return &csi.NodeGetVolumeStatsResponse{
 		Usage: []*csi.VolumeUsage{
 			{
 				Available: requirePositive(available),
@@ -298,14 +284,35 @@ func FilesystemNodeGetVolumeStats(
 				Used:      requirePositive(used),
 				Unit:      csi.VolumeUsage_BYTES,
 			},
-			{
-				Available: requirePositive(inodesFree),
-				Total:     requirePositive(inodes),
-				Used:      requirePositive(inodesUsed),
-				Unit:      csi.VolumeUsage_INODES,
-			},
 		},
-	}, nil
+	}
+
+	if includeInodes {
+		inodes, ok := (*(volMetrics.Inodes)).AsInt64()
+		if !ok {
+			log.ErrorLog(ctx, "failed to fetch available inodes")
+
+			return nil, status.Error(codes.Unknown, "failed to fetch available inodes")
+		}
+		inodesFree, ok := (*(volMetrics.InodesFree)).AsInt64()
+		if !ok {
+			log.ErrorLog(ctx, "failed to fetch free inodes")
+		}
+
+		inodesUsed, ok := (*(volMetrics.InodesUsed)).AsInt64()
+		if !ok {
+			log.ErrorLog(ctx, "failed to fetch used inodes")
+		}
+
+		res.Usage = append(res.Usage, &csi.VolumeUsage{
+			Available: requirePositive(inodesFree),
+			Total:     requirePositive(inodes),
+			Used:      requirePositive(inodesUsed),
+			Unit:      csi.VolumeUsage_INODES,
+		})
+	}
+
+	return res, nil
 }
 
 // requirePositive returns the value for `x` when it is greater or equal to 0,

internal/csi-common/utils_test.go

@@ -88,7 +88,7 @@ func TestFilesystemNodeGetVolumeStats(t *testing.T) {
 
 	// retry until a mountpoint is found
 	for {
-		stats, err := FilesystemNodeGetVolumeStats(context.TODO(), mount.New(""), cwd)
+		stats, err := FilesystemNodeGetVolumeStats(context.TODO(), mount.New(""), cwd, true)
 		if err != nil && cwd != "/" && strings.HasSuffix(err.Error(), "is not mounted") {
 			// try again with the parent directory
 			cwd = filepath.Dir(cwd)

internal/nfs/nodeserver/nodeserver.go

@@ -182,7 +182,7 @@ func (ns *NodeServer) NodeGetVolumeStats(
 	}
 
 	if stat.Mode().IsDir() {
-		return csicommon.FilesystemNodeGetVolumeStats(ctx, ns.Mounter, targetPath)
+		return csicommon.FilesystemNodeGetVolumeStats(ctx, ns.Mounter, targetPath, false)
 	}
 
 	return nil, status.Errorf(codes.InvalidArgument,

internal/rbd/nodeserver.go

@@ -1240,7 +1240,7 @@ func (ns *NodeServer) NodeGetVolumeStats(
 	}
 
 	if stat.Mode().IsDir() {
-		return csicommon.FilesystemNodeGetVolumeStats(ctx, ns.Mounter, targetPath)
+		return csicommon.FilesystemNodeGetVolumeStats(ctx, ns.Mounter, targetPath, true)
 	} else if (stat.Mode() & os.ModeDevice) == os.ModeDevice {
 		return blockNodeGetVolumeStats(ctx, targetPath)
 	}