Update cadvisor version to latest version

vendor/github.com/google/cadvisor/container/docker/BUILD

@@ -31,6 +31,7 @@ go_library(
         "//vendor/github.com/google/cadvisor/machine:go_default_library",
         "//vendor/github.com/google/cadvisor/manager/watcher:go_default_library",
         "//vendor/github.com/google/cadvisor/utils/docker:go_default_library",
+        "//vendor/github.com/google/cadvisor/zfs:go_default_library",
         "//vendor/github.com/opencontainers/runc/libcontainer/cgroups:go_default_library",
         "//vendor/github.com/opencontainers/runc/libcontainer/cgroups/fs:go_default_library",
         "//vendor/github.com/opencontainers/runc/libcontainer/configs:go_default_library",

vendor/github.com/google/cadvisor/container/docker/docker.go

@@ -17,6 +17,7 @@ package docker
 
 import (
 	"fmt"
+	"regexp"
 	"strconv"
 	"strings"
 
@@ -39,6 +40,7 @@ func Status() (v1.DockerStatus, error) {
 
 	out := v1.DockerStatus{}
 	out.Version = VersionString()
+	out.APIVersion = APIVersionString()
 	out.KernelVersion = machine.KernelVersion()
 	out.OS = dockerInfo.OperatingSystem
 	out.Hostname = dockerInfo.Name
@@ -105,7 +107,7 @@ func ValidateInfo() (*dockertypes.Info, error) {
 		}
 		dockerInfo.ServerVersion = version.Version
 	}
-	version, err := parseDockerVersion(dockerInfo.ServerVersion)
+	version, err := parseVersion(dockerInfo.ServerVersion, version_re, 3)
 	if err != nil {
 		return nil, err
 	}
@@ -129,7 +131,11 @@ func ValidateInfo() (*dockertypes.Info, error) {
 }
 
 func Version() ([]int, error) {
-	return parseDockerVersion(VersionString())
+	return parseVersion(VersionString(), version_re, 3)
+}
+
+func APIVersion() ([]int, error) {
+	return parseVersion(APIVersionString(), apiversion_re, 2)
 }
 
 func VersionString() string {
@@ -144,18 +150,29 @@ func VersionString() string {
 	return docker_version
 }
 
-// TODO: switch to a semantic versioning library.
-func parseDockerVersion(full_version_string string) ([]int, error) {
-	matches := version_re.FindAllStringSubmatch(full_version_string, -1)
+func APIVersionString() string {
+	docker_api_version := "Unknown"
+	client, err := Client()
+	if err == nil {
+		version, err := client.ServerVersion(context.Background())
+		if err == nil {
+			docker_api_version = version.APIVersion
+		}
+	}
+	return docker_api_version
+}
+
+func parseVersion(version_string string, regex *regexp.Regexp, length int) ([]int, error) {
+	matches := regex.FindAllStringSubmatch(version_string, -1)
 	if len(matches) != 1 {
-		return nil, fmt.Errorf("version string \"%v\" doesn't match expected regular expression: \"%v\"", full_version_string, version_regexp_string)
+		return nil, fmt.Errorf("version string \"%v\" doesn't match expected regular expression: \"%v\"", version_string, regex.String())
 	}
 	version_string_array := matches[0][1:]
-	version_array := make([]int, 3)
-	for index, version_string := range version_string_array {
-		version, err := strconv.Atoi(version_string)
+	version_array := make([]int, length)
+	for index, version_str := range version_string_array {
+		version, err := strconv.Atoi(version_str)
 		if err != nil {
-			return nil, fmt.Errorf("error while parsing \"%v\" in \"%v\"", version_string, full_version_string)
+			return nil, fmt.Errorf("error while parsing \"%v\" in \"%v\"", version_str, version_string)
 		}
 		version_array[index] = version
 	}

vendor/github.com/google/cadvisor/container/docker/factory.go

@@ -33,6 +33,7 @@ import (
 	"github.com/google/cadvisor/machine"
 	"github.com/google/cadvisor/manager/watcher"
 	dockerutil "github.com/google/cadvisor/utils/docker"
+	"github.com/google/cadvisor/zfs"
 
 	docker "github.com/docker/engine-api/client"
 	"github.com/golang/glog"
@@ -102,9 +103,13 @@ type dockerFactory struct {
 
 	dockerVersion []int
 
+	dockerAPIVersion []int
+
 	ignoreMetrics container.MetricSet
 
 	thinPoolWatcher *devicemapper.ThinPoolWatcher
+
+	zfsWatcher *zfs.ZfsWatcher
 }
 
 func (self *dockerFactory) String() string {
@@ -132,6 +137,7 @@ func (self *dockerFactory) NewContainerHandler(name string, inHostNamespace bool
 		self.dockerVersion,
 		self.ignoreMetrics,
 		self.thinPoolWatcher,
+		self.zfsWatcher,
 	)
 	return
 }
@@ -181,8 +187,10 @@ func (self *dockerFactory) DebugInfo() map[string][]string {
 }
 
 var (
-	version_regexp_string = `(\d+)\.(\d+)\.(\d+)`
-	version_re            = regexp.MustCompile(version_regexp_string)
+	version_regexp_string    = `(\d+)\.(\d+)\.(\d+)`
+	version_re               = regexp.MustCompile(version_regexp_string)
+	apiversion_regexp_string = `(\d+)\.(\d+)`
+	apiversion_re            = regexp.MustCompile(apiversion_regexp_string)
 )
 
 func startThinPoolWatcher(dockerInfo *dockertypes.Info) (*devicemapper.ThinPoolWatcher, error) {
@@ -218,6 +226,21 @@ func startThinPoolWatcher(dockerInfo *dockertypes.Info) (*devicemapper.ThinPoolW
 	return thinPoolWatcher, nil
 }
 
+func startZfsWatcher(dockerInfo *dockertypes.Info) (*zfs.ZfsWatcher, error) {
+	filesystem, err := dockerutil.DockerZfsFilesystem(*dockerInfo)
+	if err != nil {
+		return nil, err
+	}
+
+	zfsWatcher, err := zfs.NewZfsWatcher(filesystem)
+	if err != nil {
+		return nil, err
+	}
+
+	go zfsWatcher.Start()
+	return zfsWatcher, nil
+}
+
 func ensureThinLsKernelVersion(kernelVersion string) error {
 	// kernel 4.4.0 has the proper bug fixes to allow thin_ls to work without corrupting the thin pool
 	minKernelVersion := semver.MustParse("4.4.0")
@@ -291,7 +314,9 @@ func Register(factory info.MachineInfoFactory, fsInfo fs.FsInfo, ignoreMetrics c
 	}
 
 	// Version already validated above, assume no error here.
-	dockerVersion, _ := parseDockerVersion(dockerInfo.ServerVersion)
+	dockerVersion, _ := parseVersion(dockerInfo.ServerVersion, version_re, 3)
+
+	dockerAPIVersion, _ := APIVersion()
 
 	cgroupSubsystems, err := libcontainer.GetCgroupSubsystems()
 	if err != nil {
@@ -306,17 +331,27 @@ func Register(factory info.MachineInfoFactory, fsInfo fs.FsInfo, ignoreMetrics c
 		}
 	}
 
+	var zfsWatcher *zfs.ZfsWatcher
+	if storageDriver(dockerInfo.Driver) == zfsStorageDriver {
+		zfsWatcher, err = startZfsWatcher(dockerInfo)
+		if err != nil {
+			glog.Errorf("zfs filesystem stats will not be reported: %v", err)
+		}
+	}
+
 	glog.Infof("Registering Docker factory")
 	f := &dockerFactory{
 		cgroupSubsystems:   cgroupSubsystems,
 		client:             client,
 		dockerVersion:      dockerVersion,
+		dockerAPIVersion:   dockerAPIVersion,
 		fsInfo:             fsInfo,
 		machineInfoFactory: factory,
 		storageDriver:      storageDriver(dockerInfo.Driver),
 		storageDir:         RootDir(),
 		ignoreMetrics:      ignoreMetrics,
 		thinPoolWatcher:    thinPoolWatcher,
+		zfsWatcher:         zfsWatcher,
 	}
 
 	container.RegisterContainerHandlerFactory(f, []watcher.ContainerWatchSource{watcher.Raw})

vendor/github.com/google/cadvisor/container/docker/handler.go

@@ -29,6 +29,7 @@ import (
 	"github.com/google/cadvisor/fs"
 	info "github.com/google/cadvisor/info/v1"
 	dockerutil "github.com/google/cadvisor/utils/docker"
+	"github.com/google/cadvisor/zfs"
 
 	docker "github.com/docker/engine-api/client"
 	dockercontainer "github.com/docker/engine-api/types/container"
@@ -42,6 +43,7 @@ import (
 const (
 	// The read write layers exist here.
 	aufsRWLayer = "diff"
+
 	// Path to the directory where docker stores log files if the json logging driver is enabled.
 	pathToContainersDir = "containers"
 )
@@ -72,6 +74,12 @@ type dockerContainerHandler struct {
 	// the devicemapper device id for the container
 	deviceID string
 
+	// zfs Filesystem
+	zfsFilesystem string
+
+	// zfsParent is the parent for docker zfs
+	zfsParent string
+
 	// Time at which this container was created.
 	creationTime time.Time
 
@@ -101,6 +109,9 @@ type dockerContainerHandler struct {
 
 	// thin pool watcher
 	thinPoolWatcher *devicemapper.ThinPoolWatcher
+
+	// zfs watcher
+	zfsWatcher *zfs.ZfsWatcher
 }
 
 var _ container.ContainerHandler = &dockerContainerHandler{}
@@ -136,6 +147,7 @@ func newDockerContainerHandler(
 	dockerVersion []int,
 	ignoreMetrics container.MetricSet,
 	thinPoolWatcher *devicemapper.ThinPoolWatcher,
+	zfsWatcher *zfs.ZfsWatcher,
 ) (container.ContainerHandler, error) {
 	// Create the cgroup paths.
 	cgroupPaths := make(map[string]string, len(cgroupSubsystems.MountPoints))
@@ -172,12 +184,21 @@ func newDockerContainerHandler(
 	var (
 		rootfsStorageDir string
 		poolName         string
+		zfsFilesystem    string
+		zfsParent        string
 	)
 	switch storageDriver {
 	case aufsStorageDriver:
 		rootfsStorageDir = path.Join(storageDir, string(aufsStorageDriver), aufsRWLayer, rwLayerID)
 	case overlayStorageDriver:
 		rootfsStorageDir = path.Join(storageDir, string(overlayStorageDriver), rwLayerID)
+	case zfsStorageDriver:
+		status, err := Status()
+		if err != nil {
+			return nil, fmt.Errorf("unable to determine docker status: %v", err)
+		}
+		zfsParent = status.DriverStatus[dockerutil.DriverStatusParentDataset]
+		zfsFilesystem = path.Join(zfsParent, rwLayerID)
 	case devicemapperStorageDriver:
 		status, err := Status()
 		if err != nil {
@@ -199,10 +220,13 @@ func newDockerContainerHandler(
 		fsInfo:             fsInfo,
 		rootFs:             rootFs,
 		poolName:           poolName,
+		zfsFilesystem:      zfsFilesystem,
 		rootfsStorageDir:   rootfsStorageDir,
 		envs:               make(map[string]string),
 		ignoreMetrics:      ignoreMetrics,
 		thinPoolWatcher:    thinPoolWatcher,
+		zfsWatcher:         zfsWatcher,
+		zfsParent:          zfsParent,
 	}
 
 	// We assume that if Inspect fails then the container is not known to docker.
@@ -245,7 +269,9 @@ func newDockerContainerHandler(
 		handler.fsHandler = &dockerFsHandler{
 			fsHandler:       common.NewFsHandler(common.DefaultPeriod, rootfsStorageDir, otherStorageDir, fsInfo),
 			thinPoolWatcher: thinPoolWatcher,
+			zfsWatcher:      zfsWatcher,
 			deviceID:        handler.deviceID,
+			zfsFilesystem:   zfsFilesystem,
 		}
 	}
 
@@ -265,7 +291,7 @@ func newDockerContainerHandler(
 }
 
 // dockerFsHandler is a composite FsHandler implementation the incorporates
-// the common fs handler and a devicemapper ThinPoolWatcher.
+// the common fs handler, a devicemapper ThinPoolWatcher, and a zfsWatcher
 type dockerFsHandler struct {
 	fsHandler common.FsHandler
 
@@ -273,6 +299,11 @@ type dockerFsHandler struct {
 	thinPoolWatcher *devicemapper.ThinPoolWatcher
 	// deviceID is the id of the container's fs device
 	deviceID string
+
+	// zfsWatcher is the zfs filesystem watcher
+	zfsWatcher *zfs.ZfsWatcher
+	// zfsFilesystem is the docker zfs filesystem
+	zfsFilesystem string
 }
 
 var _ common.FsHandler = &dockerFsHandler{}
@@ -306,6 +337,15 @@ func (h *dockerFsHandler) Usage() common.FsUsage {
 		}
 	}
 
+	if h.zfsWatcher != nil {
+		zfsUsage, err := h.zfsWatcher.GetUsage(h.zfsFilesystem)
+		if err != nil {
+			glog.V(5).Infof("unable to get fs usage from zfs for filesystem %s: %v", h.zfsFilesystem, err)
+		} else {
+			usage.BaseUsageBytes = zfsUsage
+			usage.TotalUsageBytes += zfsUsage
+		}
+	}
 	return usage
 }
 
@@ -359,12 +399,14 @@ func (self *dockerContainerHandler) getFsStats(stats *info.ContainerStats) error
 		// Device has to be the pool name to correlate with the device name as
 		// set in the machine info filesystems.
 		device = self.poolName
-	case aufsStorageDriver, overlayStorageDriver, zfsStorageDriver:
+	case aufsStorageDriver, overlayStorageDriver:
 		deviceInfo, err := self.fsInfo.GetDirFsDevice(self.rootfsStorageDir)
 		if err != nil {
 			return fmt.Errorf("unable to determine device info for dir: %v: %v", self.rootfsStorageDir, err)
 		}
 		device = deviceInfo.Device
+	case zfsStorageDriver:
+		device = self.zfsParent
 	default:
 		return nil
 	}

vendor/github.com/google/cadvisor/fs/fs.go

@@ -149,6 +149,31 @@ func processMounts(mounts []*mount.Info, excludedMountpointPrefixes []string) ma
 			continue
 		}
 
+		// btrfs fix: following workaround fixes wrong btrfs Major and Minor Ids reported in /proc/self/mountinfo.
+		// instead of using values from /proc/self/mountinfo we use stat to get Ids from btrfs mount point
+		if mount.Fstype == "btrfs" && mount.Major == 0 && strings.HasPrefix(mount.Source, "/dev/") {
+
+			buf := new(syscall.Stat_t)
+			err := syscall.Stat(mount.Source, buf)
+			if err != nil {
+				glog.Warningf("stat failed on %s with error: %s", mount.Source, err)
+			} else {
+				glog.Infof("btrfs mount %#v", mount)
+				if buf.Mode&syscall.S_IFMT == syscall.S_IFBLK {
+					err := syscall.Stat(mount.Mountpoint, buf)
+					if err != nil {
+						glog.Warningf("stat failed on %s with error: %s", mount.Mountpoint, err)
+					} else {
+						glog.Infof("btrfs dev major:minor %d:%d\n", int(major(buf.Dev)), int(minor(buf.Dev)))
+						glog.Infof("btrfs rdev major:minor %d:%d\n", int(major(buf.Rdev)), int(minor(buf.Rdev)))
+
+						mount.Major = int(major(buf.Dev))
+						mount.Minor = int(minor(buf.Dev))
+					}
+				}
+			}
+		}
+
 		partitions[mount.Source] = partition{
 			fsType:     mount.Fstype,
 			mountpoint: mount.Mountpoint,

vendor/github.com/google/cadvisor/info/v1/docker.go

@@ -17,6 +17,7 @@ package v1
 
 type DockerStatus struct {
 	Version       string            `json:"version"`
+	APIVersion    string            `json:"api_version"`
 	KernelVersion string            `json:"kernel_version"`
 	OS            string            `json:"os"`
 	Hostname      string            `json:"hostname"`

vendor/github.com/google/cadvisor/info/v1/machine.go

@@ -196,6 +196,9 @@ type VersionInfo struct {
 	// Docker version.
 	DockerVersion string `json:"docker_version"`
 
+	// Docker API Version
+	DockerAPIVersion string `json:"docker_api_version"`
+
 	// cAdvisor version.
 	CadvisorVersion string `json:"cadvisor_version"`
 	// cAdvisor git revision.

vendor/github.com/google/cadvisor/info/v2/machine.go

@@ -31,6 +31,9 @@ type Attributes struct {
 	// Docker version.
 	DockerVersion string `json:"docker_version"`
 
+	// Docker API version.
+	DockerAPIVersion string `json:"docker_api_version"`
+
 	// cAdvisor version.
 	CadvisorVersion string `json:"cadvisor_version"`
 
@@ -74,6 +77,7 @@ func GetAttributes(mi *v1.MachineInfo, vi *v1.VersionInfo) Attributes {
 		KernelVersion:      vi.KernelVersion,
 		ContainerOsVersion: vi.ContainerOsVersion,
 		DockerVersion:      vi.DockerVersion,
+		DockerAPIVersion:   vi.DockerAPIVersion,
 		CadvisorVersion:    vi.CadvisorVersion,
 		NumCores:           mi.NumCores,
 		CpuFrequency:       mi.CpuFrequency,

vendor/github.com/google/cadvisor/manager/manager.go

@@ -1255,11 +1255,13 @@ func getVersionInfo() (*info.VersionInfo, error) {
 	kernel_version := machine.KernelVersion()
 	container_os := machine.ContainerOsVersion()
 	docker_version := docker.VersionString()
+	docker_api_version := docker.APIVersionString()
 
 	return &info.VersionInfo{
 		KernelVersion:      kernel_version,
 		ContainerOsVersion: container_os,
 		DockerVersion:      docker_version,
+		DockerAPIVersion:   docker_api_version,
 		CadvisorVersion:    version.Info["version"],
 		CadvisorRevision:   version.Info["revision"],
 	}, nil

vendor/github.com/google/cadvisor/pages/docker.go

@@ -40,6 +40,7 @@ func toStatusKV(status info.DockerStatus) ([]keyVal, []keyVal) {
 	}
 	return []keyVal{
 		{Key: "Docker Version", Value: status.Version},
+		{Key: "Docker API Version", Value: status.APIVersion},
 		{Key: "Kernel Version", Value: status.KernelVersion},
 		{Key: "OS Version", Value: status.OS},
 		{Key: "Host Name", Value: status.Hostname},

vendor/github.com/google/cadvisor/utils/docker/docker.go

@@ -23,11 +23,12 @@ import (
 )
 
 const (
-	DockerInfoDriver         = "Driver"
-	DockerInfoDriverStatus   = "DriverStatus"
-	DriverStatusPoolName     = "Pool Name"
-	DriverStatusDataLoopFile = "Data loop file"
-	DriverStatusMetadataFile = "Metadata file"
+	DockerInfoDriver          = "Driver"
+	DockerInfoDriverStatus    = "DriverStatus"
+	DriverStatusPoolName      = "Pool Name"
+	DriverStatusDataLoopFile  = "Data loop file"
+	DriverStatusMetadataFile  = "Metadata file"
+	DriverStatusParentDataset = "Parent Dataset"
 )
 
 func DriverStatusValue(status [][2]string, target string) string {
@@ -68,3 +69,12 @@ func DockerMetadataDevice(info dockertypes.Info) (string, error) {
 
 	return metadataDevice, nil
 }
+
+func DockerZfsFilesystem(info dockertypes.Info) (string, error) {
+	filesystem := DriverStatusValue(info.DriverStatus, DriverStatusParentDataset)
+	if len(filesystem) == 0 {
+		return "", fmt.Errorf("Could not get zfs filesystem")
+	}
+
+	return filesystem, nil
+}

vendor/github.com/google/cadvisor/utils/sysfs/sysfs.go

@@ -70,8 +70,8 @@ type SysFs interface {
 
 type realSysFs struct{}
 
-func NewRealSysFs() (SysFs, error) {
-	return &realSysFs{}, nil
+func NewRealSysFs() SysFs {
+	return &realSysFs{}
 }
 
 func (self *realSysFs) GetBlockDevices() ([]os.FileInfo, error) {

vendor/github.com/google/cadvisor/utils/sysinfo/sysinfo.go

@@ -155,10 +155,7 @@ func GetCacheInfo(sysFs sysfs.SysFs, id int) ([]sysfs.CacheInfo, error) {
 
 func GetNetworkStats(name string) (info.InterfaceStats, error) {
 	// TODO(rjnagal): Take syfs as an argument.
-	sysFs, err := sysfs.NewRealSysFs()
-	if err != nil {
-		return info.InterfaceStats{}, err
-	}
+	sysFs := sysfs.NewRealSysFs()
 	return getNetworkStats(name, sysFs)
 }
 

vendor/github.com/google/cadvisor/zfs/BUILD

@@ -0,0 +1,31 @@
+package(default_visibility = ["//visibility:public"])
+
+licenses(["notice"])
+
+load(
+    "@io_bazel_rules_go//go:def.bzl",
+    "go_library",
+)
+
+go_library(
+    name = "go_default_library",
+    srcs = ["watcher.go"],
+    tags = ["automanaged"],
+    deps = [
+        "//vendor/github.com/golang/glog:go_default_library",
+        "//vendor/github.com/mistifyio/go-zfs:go_default_library",
+    ],
+)
+
+filegroup(
+    name = "package-srcs",
+    srcs = glob(["**"]),
+    tags = ["automanaged"],
+    visibility = ["//visibility:private"],
+)
+
+filegroup(
+    name = "all-srcs",
+    srcs = [":package-srcs"],
+    tags = ["automanaged"],
+)

vendor/github.com/google/cadvisor/zfs/watcher.go

@@ -0,0 +1,113 @@
+// Copyright 2016 Google Inc. All Rights Reserved.
+//
+// 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 zfs
+
+import (
+	"fmt"
+	"sync"
+	"time"
+
+	"github.com/golang/glog"
+	zfs "github.com/mistifyio/go-zfs"
+)
+
+// zfsWatcher maintains a cache of filesystem -> usage stats for a
+// zfs filesystem
+type ZfsWatcher struct {
+	filesystem string
+	lock       *sync.RWMutex
+	cache      map[string]uint64
+	period     time.Duration
+	stopChan   chan struct{}
+}
+
+// NewThinPoolWatcher returns a new ThinPoolWatcher for the given devicemapper
+// thin pool name and metadata device or an error.
+func NewZfsWatcher(filesystem string) (*ZfsWatcher, error) {
+
+	return &ZfsWatcher{
+		filesystem: filesystem,
+		lock:       &sync.RWMutex{},
+		cache:      make(map[string]uint64),
+		period:     15 * time.Second,
+		stopChan:   make(chan struct{}),
+	}, nil
+}
+
+// Start starts the ZfsWatcher.
+func (w *ZfsWatcher) Start() {
+	err := w.Refresh()
+	if err != nil {
+		glog.Errorf("encountered error refreshing zfs watcher: %v", err)
+	}
+
+	for {
+		select {
+		case <-w.stopChan:
+			return
+		case <-time.After(w.period):
+			start := time.Now()
+			err = w.Refresh()
+			if err != nil {
+				glog.Errorf("encountered error refreshing zfs watcher: %v", err)
+			}
+
+			// print latency for refresh
+			duration := time.Since(start)
+			glog.V(5).Infof("zfs(%d) took %s", start.Unix(), duration)
+		}
+	}
+}
+
+// Stop stops the ZfsWatcher.
+func (w *ZfsWatcher) Stop() {
+	close(w.stopChan)
+}
+
+// GetUsage gets the cached usage value of the given filesystem.
+func (w *ZfsWatcher) GetUsage(filesystem string) (uint64, error) {
+	w.lock.RLock()
+	defer w.lock.RUnlock()
+
+	v, ok := w.cache[filesystem]
+	if !ok {
+		return 0, fmt.Errorf("no cached value for usage of filesystem %v", filesystem)
+	}
+
+	return v, nil
+}
+
+// Refresh performs a zfs get
+func (w *ZfsWatcher) Refresh() error {
+	w.lock.Lock()
+	defer w.lock.Unlock()
+	newCache := make(map[string]uint64)
+	parent, err := zfs.GetDataset(w.filesystem)
+	if err != nil {
+		glog.Errorf("encountered error getting zfs filesystem: %s: %v", w.filesystem, err)
+		return err
+	}
+	children, err := parent.Children(0)
+	if err != nil {
+		glog.Errorf("encountered error getting children of zfs filesystem: %s: %v", w.filesystem, err)
+		return err
+	}
+
+	for _, ds := range children {
+		newCache[ds.Name] = ds.Used
+	}
+
+	w.cache = newCache
+	return nil
+}