fs: get inodes and disk usage via pure go

Author: Igor German

container/common/fsHandler.go

@@ -51,7 +51,6 @@ type realFsHandler struct {
 }
 
 const (
-	timeout          = 2 * time.Minute
 	maxBackoffFactor = 20
 )
 
@@ -74,36 +73,34 @@ func NewFsHandler(period time.Duration, rootfs, extraDir string, fsInfo fs.FsInf
 
 func (fh *realFsHandler) update() error {
 	var (
-		baseUsage, extraDirUsage, inodeUsage    uint64
-		rootDiskErr, rootInodeErr, extraDiskErr error
+		rootUsage, extraUsage fs.UsageInfo
+		rootErr, extraErr     error
 	)
 	// TODO(vishh): Add support for external mounts.
 	if fh.rootfs != "" {
-		baseUsage, rootDiskErr = fh.fsInfo.GetDirDiskUsage(fh.rootfs, timeout)
-		inodeUsage, rootInodeErr = fh.fsInfo.GetDirInodeUsage(fh.rootfs, timeout)
+		rootUsage, rootErr = fh.fsInfo.GetDirUsage(fh.rootfs)
 	}
 
 	if fh.extraDir != "" {
-		extraDirUsage, extraDiskErr = fh.fsInfo.GetDirDiskUsage(fh.extraDir, timeout)
+		extraUsage, extraErr = fh.fsInfo.GetDirUsage(fh.extraDir)
 	}
 
 	// Wait to handle errors until after all operartions are run.
 	// An error in one will not cause an early return, skipping others
 	fh.Lock()
 	defer fh.Unlock()
 	fh.lastUpdate = time.Now()
-	if rootInodeErr == nil && fh.rootfs != "" {
-		fh.usage.InodeUsage = inodeUsage
+	if fh.rootfs != "" && rootErr == nil {
+		fh.usage.InodeUsage = rootUsage.Inodes
+		fh.usage.TotalUsageBytes = rootUsage.Bytes + extraUsage.Bytes
 	}
-	if rootDiskErr == nil && fh.rootfs != "" {
-		fh.usage.TotalUsageBytes = baseUsage + extraDirUsage
-	}
-	if extraDiskErr == nil && fh.extraDir != "" {
-		fh.usage.BaseUsageBytes = baseUsage
+	if fh.extraDir != "" && extraErr == nil {
+		fh.usage.BaseUsageBytes = rootUsage.Bytes
 	}
+
 	// Combine errors into a single error to return
-	if rootDiskErr != nil || rootInodeErr != nil || extraDiskErr != nil {
-		return fmt.Errorf("rootDiskErr: %v, rootInodeErr: %v, extraDiskErr: %v", rootDiskErr, rootInodeErr, extraDiskErr)
+	if rootErr != nil || extraErr != nil {
+		return fmt.Errorf("rootDiskErr: %v, extraDiskErr: %v", rootErr, extraErr)
 	}
 	return nil
 }

fs/fs.go

@@ -19,7 +19,6 @@ package fs
 
 import (
 	"bufio"
-	"bytes"
 	"fmt"
 	"io/ioutil"
 	"os"
@@ -30,7 +29,6 @@ import (
 	"strconv"
 	"strings"
 	"syscall"
-	"time"
 
 	"github.com/docker/docker/pkg/mount"
 	"github.com/google/cadvisor/devicemapper"
@@ -47,26 +45,6 @@ const (
 	LabelCrioImages   = "crio-images"
 )
 
-// The maximum number of `du` and `find` tasks that can be running at once.
-const maxConcurrentOps = 20
-
-// A pool for restricting the number of consecutive `du` and `find` tasks running.
-var pool = make(chan struct{}, maxConcurrentOps)
-
-func init() {
-	for i := 0; i < maxConcurrentOps; i++ {
-		releaseToken()
-	}
-}
-
-func claimToken() {
-	<-pool
-}
-
-func releaseToken() {
-	pool <- struct{}{}
-}
-
 type partition struct {
 	mountpoint string
 	major      uint
@@ -559,78 +537,62 @@ func (self *RealFsInfo) GetDirFsDevice(dir string) (*DeviceInfo, error) {
 	return nil, fmt.Errorf("could not find device with major: %d, minor: %d in cached partitions map", major, minor)
 }
 
-func (self *RealFsInfo) GetDirDiskUsage(dir string, timeout time.Duration) (uint64, error) {
-	claimToken()
-	defer releaseToken()
-	return GetDirDiskUsage(dir, timeout)
-}
+func (self *RealFsInfo) GetDirUsage(dir string) (UsageInfo, error) {
+	var usage UsageInfo
 
-func GetDirDiskUsage(dir string, timeout time.Duration) (uint64, error) {
 	if dir == "" {
-		return 0, fmt.Errorf("invalid directory")
-	}
-	cmd := exec.Command("ionice", "-c3", "nice", "-n", "19", "du", "-s", dir)
-	stdoutp, err := cmd.StdoutPipe()
-	if err != nil {
-		return 0, fmt.Errorf("failed to setup stdout for cmd %v - %v", cmd.Args, err)
-	}
-	stderrp, err := cmd.StderrPipe()
-	if err != nil {
-		return 0, fmt.Errorf("failed to setup stderr for cmd %v - %v", cmd.Args, err)
+		return usage, fmt.Errorf("invalid directory")
 	}
 
-	if err := cmd.Start(); err != nil {
-		return 0, fmt.Errorf("failed to exec du - %v", err)
-	}
-	timer := time.AfterFunc(timeout, func() {
-		klog.Warningf("Killing cmd %v due to timeout(%s)", cmd.Args, timeout.String())
-		cmd.Process.Kill()
-	})
-	stdoutb, souterr := ioutil.ReadAll(stdoutp)
-	if souterr != nil {
-		klog.Errorf("Failed to read from stdout for cmd %v - %v", cmd.Args, souterr)
-	}
-	stderrb, _ := ioutil.ReadAll(stderrp)
-	err = cmd.Wait()
-	timer.Stop()
+	rootInfo, err := os.Stat(dir)
 	if err != nil {
-		return 0, fmt.Errorf("du command failed on %s with output stdout: %s, stderr: %s - %v", dir, string(stdoutb), string(stderrb), err)
+		return usage, fmt.Errorf("could not stat %q to get inode usage: %v", dir, err)
 	}
-	stdout := string(stdoutb)
-	usageInKb, err := strconv.ParseUint(strings.Fields(stdout)[0], 10, 64)
-	if err != nil {
-		return 0, fmt.Errorf("cannot parse 'du' output %s - %s", stdout, err)
+
+	rootStat, ok := rootInfo.Sys().(*syscall.Stat_t)
+	if !ok {
+		return usage, fmt.Errorf("unsuported fileinfo for getting inode usage of %q", dir)
 	}
-	return usageInKb * 1024, nil
-}
 
-func (self *RealFsInfo) GetDirInodeUsage(dir string, timeout time.Duration) (uint64, error) {
-	claimToken()
-	defer releaseToken()
-	return GetDirInodeUsage(dir, timeout)
-}
+	rootDevId := rootStat.Dev
 
-func GetDirInodeUsage(dir string, timeout time.Duration) (uint64, error) {
-	if dir == "" {
-		return 0, fmt.Errorf("invalid directory")
-	}
-	var counter byteCounter
-	var stderr bytes.Buffer
-	findCmd := exec.Command("ionice", "-c3", "nice", "-n", "19", "find", dir, "-xdev", "-printf", ".")
-	findCmd.Stdout, findCmd.Stderr = &counter, &stderr
-	if err := findCmd.Start(); err != nil {
-		return 0, fmt.Errorf("failed to exec cmd %v - %v; stderr: %v", findCmd.Args, err, stderr.String())
-	}
-	timer := time.AfterFunc(timeout, func() {
-		klog.Warningf("Killing cmd %v due to timeout(%s)", findCmd.Args, timeout.String())
-		findCmd.Process.Kill()
+	// dedupedInode stores inodes that could be duplicates (nlink > 1)
+	dedupedInodes := make(map[uint64]struct{})
+
+	err = filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
+		if os.IsNotExist(err) {
+			// expected if files appear/vanish
+			return nil
+		}
+		if err != nil {
+			return fmt.Errorf("unable to count inodes for part of dir %s: %s", dir, err)
+		}
+
+		s, ok := info.Sys().(*syscall.Stat_t)
+		if !ok {
+			return fmt.Errorf("unsupported fileinfo; could not convert to stat_t")
+		}
+
+		if s.Dev != rootDevId {
+			// don't descend into directories on other devices
+			return filepath.SkipDir
+		}
+		if s.Nlink > 1 {
+			if _, ok := dedupedInodes[s.Ino]; !ok {
+				// Dedupe things that could be hardlinks
+				dedupedInodes[s.Ino] = struct{}{}
+
+				usage.Bytes += uint64(s.Blocks) * uint64(512)
+				usage.Inodes++
+			}
+		} else {
+			usage.Bytes += uint64(s.Blocks) * uint64(512)
+			usage.Inodes++
+		}
+		return nil
 	})
-	err := findCmd.Wait()
-	timer.Stop()
-	if err != nil {
-		return 0, fmt.Errorf("cmd %v failed. stderr: %s; err: %v", findCmd.Args, stderr.String(), err)
-	}
-	return counter.bytesWritten, nil
+
+	return usage, nil
 }
 
 func getVfsStats(path string) (total uint64, free uint64, avail uint64, inodes uint64, inodesFree uint64, err error) {

fs/fs_test.go

@@ -20,7 +20,6 @@ import (
 	"os"
 	"reflect"
 	"testing"
-	"time"
 
 	"github.com/docker/docker/pkg/mount"
 	"github.com/stretchr/testify/assert"
@@ -101,9 +100,9 @@ func TestDirDiskUsage(t *testing.T) {
 	fi, err := f.Stat()
 	as.NoError(err)
 	expectedSize := uint64(fi.Size())
-	size, err := fsInfo.GetDirDiskUsage(dir, time.Minute)
+	usage, err := fsInfo.GetDirUsage(dir)
 	as.NoError(err)
-	as.True(expectedSize <= size, "expected dir size to be at-least %d; got size: %d", expectedSize, size)
+	as.True(expectedSize <= usage.Bytes, "expected dir size to be at-least %d; got size: %d", expectedSize, usage.Bytes)
 }
 
 func TestDirInodeUsage(t *testing.T) {
@@ -118,10 +117,10 @@ func TestDirInodeUsage(t *testing.T) {
 		_, err := ioutil.TempFile(dir, "")
 		require.NoError(t, err)
 	}
-	inodes, err := fsInfo.GetDirInodeUsage(dir, time.Minute)
+	usage, err := fsInfo.GetDirUsage(dir)
 	as.NoError(err)
 	// We sould get numFiles+1 inodes, since we get 1 inode for each file, plus 1 for the directory
-	as.True(uint64(numFiles+1) == inodes, "expected inodes in dir to be %d; got inodes: %d", numFiles+1, inodes)
+	as.True(uint64(numFiles+1) == usage.Inodes, "expected inodes in dir to be %d; got inodes: %d", numFiles+1, usage.Inodes)
 }
 
 var dmStatusTests = []struct {

fs/types.go

@@ -16,7 +16,6 @@ package fs
 
 import (
 	"errors"
-	"time"
 )
 
 type DeviceInfo struct {
@@ -62,6 +61,11 @@ type DiskStats struct {
 	WeightedIoTime  uint64
 }
 
+type UsageInfo struct {
+	Bytes  uint64
+	Inodes uint64
+}
+
 // ErrNoSuchDevice is the error indicating the requested device does not exist.
 var ErrNoSuchDevice = errors.New("cadvisor: no such device")
 
@@ -72,11 +76,8 @@ type FsInfo interface {
 	// Returns capacity and free space, in bytes, of the set of mounts passed.
 	GetFsInfoForPath(mountSet map[string]struct{}) ([]Fs, error)
 
-	// Returns number of bytes occupied by 'dir'.
-	GetDirDiskUsage(dir string, timeout time.Duration) (uint64, error)
-
-	// Returns number of inodes used by 'dir'.
-	GetDirInodeUsage(dir string, timeout time.Duration) (uint64, error)
+	// GetDirUsage returns a usage information for 'dir'.
+	GetDirUsage(dir string) (UsageInfo, error)
 
 	// GetDeviceInfoByFsUUID returns the information of the device with the
 	// specified filesystem uuid. If no such device exists, this function will