Merge pull request #2968 from cyphar/cgroup2-io-stats

cgroup2: map io.stats to v1 blkio.stats correctly

libcontainer/cgroups/fs2/io.go

@@ -8,6 +8,8 @@ import (
 	"strconv"
 	"strings"
 
+	"github.com/sirupsen/logrus"
+
 	"github.com/opencontainers/runc/libcontainer/cgroups"
 	"github.com/opencontainers/runc/libcontainer/cgroups/fscommon"
 	"github.com/opencontainers/runc/libcontainer/configs"
@@ -88,22 +90,22 @@ func readCgroup2MapFile(dirPath string, name string) (map[string][]string, error
 }
 
 func statIo(dirPath string, stats *cgroups.Stats) error {
-	// more details on the io.stat file format: https://www.kernel.org/doc/Documentation/cgroup-v2.txt
-	var ioServiceBytesRecursive []cgroups.BlkioStatEntry
 	values, err := readCgroup2MapFile(dirPath, "io.stat")
 	if err != nil {
 		return err
 	}
+	// more details on the io.stat file format: https://www.kernel.org/doc/Documentation/cgroup-v2.txt
+	var parsedStats cgroups.BlkioStats
 	for k, v := range values {
 		d := strings.Split(k, ":")
 		if len(d) != 2 {
 			continue
 		}
-		major, err := strconv.ParseUint(d[0], 10, 0)
+		major, err := strconv.ParseUint(d[0], 10, 64)
 		if err != nil {
 			return err
 		}
-		minor, err := strconv.ParseUint(d[1], 10, 0)
+		minor, err := strconv.ParseUint(d[1], 10, 64)
 		if err != nil {
 			return err
 		}
@@ -115,15 +117,32 @@ func statIo(dirPath string, stats *cgroups.Stats) error {
 			}
 			op := d[0]
 
-			// Accommodate the cgroup v1 naming
+			// Map to the cgroupv1 naming and layout (in separate tables).
+			var targetTable *[]cgroups.BlkioStatEntry
 			switch op {
+			// Equivalent to cgroupv1's blkio.io_service_bytes.
 			case "rbytes":
 				op = "Read"
+				targetTable = &parsedStats.IoServiceBytesRecursive
 			case "wbytes":
 				op = "Write"
+				targetTable = &parsedStats.IoServiceBytesRecursive
+			// Equivalent to cgroupv1's blkio.io_serviced.
+			case "rios":
+				op = "Read"
+				targetTable = &parsedStats.IoServicedRecursive
+			case "wios":
+				op = "Write"
+				targetTable = &parsedStats.IoServicedRecursive
+			default:
+				// Skip over entries we cannot map to cgroupv1 stats for now.
+				// In the future we should expand the stats struct to include
+				// them.
+				logrus.Debugf("cgroupv2 io stats: skipping over unmappable %s entry", item)
+				continue
 			}
 
-			value, err := strconv.ParseUint(d[1], 10, 0)
+			value, err := strconv.ParseUint(d[1], 10, 64)
 			if err != nil {
 				return err
 			}
@@ -134,9 +153,9 @@ func statIo(dirPath string, stats *cgroups.Stats) error {
 				Minor: minor,
 				Value: value,
 			}
-			ioServiceBytesRecursive = append(ioServiceBytesRecursive, entry)
+			*targetTable = append(*targetTable, entry)
 		}
 	}
-	stats.BlkioStats = cgroups.BlkioStats{IoServiceBytesRecursive: ioServiceBytesRecursive}
+	stats.BlkioStats = parsedStats
 	return nil
 }

libcontainer/cgroups/fs2/io_test.go

@@ -0,0 +1,87 @@
+package fs2
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"reflect"
+	"sort"
+	"testing"
+
+	"github.com/opencontainers/runc/libcontainer/cgroups"
+	"github.com/opencontainers/runc/libcontainer/cgroups/fscommon"
+)
+
+const exampleIoStatData = `254:1 rbytes=6901432320 wbytes=14245535744 rios=263278 wios=248603 dbytes=0 dios=0
+254:0 rbytes=2702336 wbytes=0 rios=97 wios=0 dbytes=0 dios=0
+259:0 rbytes=6911345664 wbytes=14245536256 rios=264538 wios=244914 dbytes=530485248 dios=2`
+
+var exampleIoStatsParsed = cgroups.BlkioStats{
+	IoServiceBytesRecursive: []cgroups.BlkioStatEntry{
+		{Major: 254, Minor: 1, Value: 6901432320, Op: "Read"},
+		{Major: 254, Minor: 1, Value: 14245535744, Op: "Write"},
+		{Major: 254, Minor: 0, Value: 2702336, Op: "Read"},
+		{Major: 254, Minor: 0, Value: 0, Op: "Write"},
+		{Major: 259, Minor: 0, Value: 6911345664, Op: "Read"},
+		{Major: 259, Minor: 0, Value: 14245536256, Op: "Write"},
+	},
+	IoServicedRecursive: []cgroups.BlkioStatEntry{
+		{Major: 254, Minor: 1, Value: 263278, Op: "Read"},
+		{Major: 254, Minor: 1, Value: 248603, Op: "Write"},
+		{Major: 254, Minor: 0, Value: 97, Op: "Read"},
+		{Major: 254, Minor: 0, Value: 0, Op: "Write"},
+		{Major: 259, Minor: 0, Value: 264538, Op: "Read"},
+		{Major: 259, Minor: 0, Value: 244914, Op: "Write"},
+	},
+}
+
+func lessBlkioStatEntry(a, b cgroups.BlkioStatEntry) bool {
+	if a.Major != b.Major {
+		return a.Major < b.Major
+	}
+	if a.Minor != b.Minor {
+		return a.Minor < b.Minor
+	}
+	if a.Op != b.Op {
+		return a.Op < b.Op
+	}
+	return a.Value < b.Value
+}
+
+func sortBlkioStats(stats *cgroups.BlkioStats) {
+	for _, table := range []*[]cgroups.BlkioStatEntry{
+		&stats.IoServicedRecursive,
+		&stats.IoServiceBytesRecursive,
+	} {
+		sort.SliceStable(*table, func(i, j int) bool { return lessBlkioStatEntry((*table)[i], (*table)[j]) })
+	}
+}
+
+func TestStatIo(t *testing.T) {
+	// We're using a fake cgroupfs.
+	fscommon.TestMode = true
+
+	fakeCgroupDir, err := ioutil.TempDir("", "runc-stat-io-test.*")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(fakeCgroupDir)
+	statPath := filepath.Join(fakeCgroupDir, "io.stat")
+
+	if err := ioutil.WriteFile(statPath, []byte(exampleIoStatData), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	var gotStats cgroups.Stats
+	if err := statIo(fakeCgroupDir, &gotStats); err != nil {
+		t.Error(err)
+	}
+
+	// Sort the output since statIo uses a map internally.
+	sortBlkioStats(&gotStats.BlkioStats)
+	sortBlkioStats(&exampleIoStatsParsed)
+
+	if !reflect.DeepEqual(gotStats.BlkioStats, exampleIoStatsParsed) {
+		t.Errorf("parsed cgroupv2 io.stat doesn't match expected result: \ngot %#v\nexpected %#v\n", gotStats.BlkioStats, exampleIoStatsParsed)
+	}
+}