more Cgroups v1 cleanups

remove all conditionals for IsCgroup2UnifiedMode and cgroupv2.Enabled
and assume Cgroups v2.

Also remove cgroup2 and additionalControllers from CgroupControl struct and all the
conditionals resulting from it.

Signed-off-by: Lokesh Mandvekar <[email protected]>

Author: lsm5

common/pkg/cgroups/blkio_linux.go

@@ -3,10 +3,6 @@
 package cgroups
 
 import (
-	"bufio"
-	"errors"
-	"fmt"
-	"os"
 	"path/filepath"
 	"strconv"
 	"strings"
@@ -26,23 +22,16 @@ func getBlkioHandler() *linuxBlkioHandler {
 
 // Apply set the specified constraints.
 func (c *linuxBlkioHandler) Apply(ctr *CgroupControl, res *cgroups.Resources) error {
-	if ctr.cgroup2 {
-		man, err := fs2.NewManager(ctr.config, filepath.Join(cgroupRoot, ctr.config.Path))
-		if err != nil {
-			return err
-		}
-		return man.Set(res)
+	man, err := fs2.NewManager(ctr.config, filepath.Join(cgroupRoot, ctr.config.Path))
+	if err != nil {
+		return err
 	}
-	path := filepath.Join(cgroupRoot, Blkio, ctr.config.Path)
-	return c.Blkio.Set(path, res)
+	return man.Set(res)
 }
 
 // Create the cgroup.
 func (c *linuxBlkioHandler) Create(ctr *CgroupControl) (bool, error) {
-	if ctr.cgroup2 {
-		return false, nil
-	}
-	return ctr.createCgroupDirectory(Blkio)
+	return false, nil
 }
 
 // Destroy the cgroup.
@@ -54,94 +43,45 @@ func (c *linuxBlkioHandler) Destroy(ctr *CgroupControl) error {
 func (c *linuxBlkioHandler) Stat(ctr *CgroupControl, m *cgroups.Stats) error {
 	var ioServiceBytesRecursive []cgroups.BlkioStatEntry
 
-	if ctr.cgroup2 {
-		// more details on the io.stat file format:X https://facebookmicrosites.github.io/cgroup2/docs/io-controller.html
-		values, err := readCgroup2MapFile(ctr, "io.stat")
+	// more details on the io.stat file format:X https://facebookmicrosites.github.io/cgroup2/docs/io-controller.html
+	values, err := readCgroup2MapFile(ctr, "io.stat")
+	if err != nil {
+		return err
+	}
+	for k, v := range values {
+		d := strings.Split(k, ":")
+		if len(d) != 2 {
+			continue
+		}
+		minor, err := strconv.ParseUint(d[0], 10, 0)
 		if err != nil {
 			return err
 		}
-		for k, v := range values {
-			d := strings.Split(k, ":")
-			if len(d) != 2 {
-				continue
-			}
-			minor, err := strconv.ParseUint(d[0], 10, 0)
-			if err != nil {
-				return err
-			}
-			major, err := strconv.ParseUint(d[1], 10, 0)
-			if err != nil {
-				return err
-			}
-
-			for _, item := range v {
-				d := strings.Split(item, "=")
-				if len(d) != 2 {
-					continue
-				}
-				op := d[0]
-
-				// Accommodate the cgroup v1 naming
-				switch op {
-				case "rbytes":
-					op = "read"
-				case "wbytes":
-					op = "write"
-				}
-
-				value, err := strconv.ParseUint(d[1], 10, 0)
-				if err != nil {
-					return err
-				}
-
-				entry := cgroups.BlkioStatEntry{
-					Op:    op,
-					Major: major,
-					Minor: minor,
-					Value: value,
-				}
-				ioServiceBytesRecursive = append(ioServiceBytesRecursive, entry)
-			}
-		}
-	} else {
-		BlkioRoot := ctr.getCgroupv1Path(Blkio)
-
-		p := filepath.Join(BlkioRoot, "blkio.throttle.io_service_bytes_recursive")
-		f, err := os.Open(p)
+		major, err := strconv.ParseUint(d[1], 10, 0)
 		if err != nil {
-			if errors.Is(err, os.ErrNotExist) {
-				return nil
-			}
-			return fmt.Errorf("open %s: %w", p, err)
+			return err
 		}
-		defer f.Close()
 
-		scanner := bufio.NewScanner(f)
-		for scanner.Scan() {
-			line := scanner.Text()
-			parts := strings.Fields(line)
-			if len(parts) < 3 {
-				continue
-			}
-			d := strings.Split(parts[0], ":")
+		for _, item := range v {
+			d := strings.Split(item, "=")
 			if len(d) != 2 {
 				continue
 			}
-			minor, err := strconv.ParseUint(d[0], 10, 0)
-			if err != nil {
-				return err
-			}
-			major, err := strconv.ParseUint(d[1], 10, 0)
-			if err != nil {
-				return err
+			op := d[0]
+
+			// Accommodate the cgroup v1 naming
+			switch op {
+			case "rbytes":
+				op = "read"
+			case "wbytes":
+				op = "write"
 			}
 
-			op := parts[1]
-
-			value, err := strconv.ParseUint(parts[2], 10, 0)
+			value, err := strconv.ParseUint(d[1], 10, 0)
 			if err != nil {
 				return err
 			}
+
 			entry := cgroups.BlkioStatEntry{
 				Op:    op,
 				Major: major,
@@ -150,9 +90,6 @@ func (c *linuxBlkioHandler) Stat(ctr *CgroupControl, m *cgroups.Stats) error {
 			}
 			ioServiceBytesRecursive = append(ioServiceBytesRecursive, entry)
 		}
-		if err := scanner.Err(); err != nil {
-			return fmt.Errorf("parse %s: %w", p, err)
-		}
 	}
 	m.BlkioStats.IoServiceBytesRecursive = ioServiceBytesRecursive
 	return nil