diff --git a/libcontainer/cgroups/cgroups.go b/libcontainer/cgroups/cgroups.go index 071f8f2e..a16a68e9 100644 --- a/libcontainer/cgroups/cgroups.go +++ b/libcontainer/cgroups/cgroups.go @@ -3,8 +3,6 @@ package cgroups import ( - "fmt" - "github.com/opencontainers/runc/libcontainer/configs" ) @@ -51,25 +49,3 @@ type Manager interface { // Whether the cgroup path exists or not Exists() bool } - -type NotFoundError struct { - Subsystem string -} - -func (e *NotFoundError) Error() string { - return fmt.Sprintf("mountpoint for %s not found", e.Subsystem) -} - -func NewNotFoundError(sub string) error { - return &NotFoundError{ - Subsystem: sub, - } -} - -func IsNotFound(err error) bool { - if err == nil { - return false - } - _, ok := err.(*NotFoundError) - return ok -} diff --git a/libcontainer/cgroups/utils.go b/libcontainer/cgroups/utils.go index b1171d8d..b86c4151 100644 --- a/libcontainer/cgroups/utils.go +++ b/libcontainer/cgroups/utils.go @@ -20,7 +20,6 @@ import ( ) const ( - CgroupNamePrefix = "name=" CgroupProcesses = "cgroup.procs" unifiedMountpoint = "/sys/fs/cgroup" ) @@ -28,8 +27,6 @@ const ( var ( isUnifiedOnce sync.Once isUnified bool - - errUnified = errors.New("not implemented for cgroup v2 unified hierarchy") ) // HugePageSizeUnitList is a list of the units used by the linux kernel when @@ -51,126 +48,12 @@ func IsCgroup2UnifiedMode() bool { return isUnified } -// https://www.kernel.org/doc/Documentation/cgroup-v1/cgroups.txt -func FindCgroupMountpoint(cgroupPath, subsystem string) (string, error) { - if IsCgroup2UnifiedMode() { - return "", errUnified - } - mnt, _, err := FindCgroupMountpointAndRoot(cgroupPath, subsystem) - return mnt, err -} - -func FindCgroupMountpointAndRoot(cgroupPath, subsystem string) (string, string, error) { - if IsCgroup2UnifiedMode() { - return "", "", errUnified - } - - // We are not using mount.GetMounts() because it's super-inefficient, - // parsing it directly sped up x10 times because of not using Sscanf. - // It was one of two major performance drawbacks in container start. - if !isSubsystemAvailable(subsystem) { - return "", "", NewNotFoundError(subsystem) - } - - f, err := os.Open("/proc/self/mountinfo") - if err != nil { - return "", "", err - } - defer f.Close() - - return findCgroupMountpointAndRootFromReader(f, cgroupPath, subsystem) -} - -func findCgroupMountpointAndRootFromReader(reader io.Reader, cgroupPath, subsystem string) (string, string, error) { - scanner := bufio.NewScanner(reader) - for scanner.Scan() { - txt := scanner.Text() - fields := strings.Fields(txt) - if len(fields) < 9 { - continue - } - if strings.HasPrefix(fields[4], cgroupPath) { - for _, opt := range strings.Split(fields[len(fields)-1], ",") { - if opt == subsystem { - return fields[4], fields[3], nil - } - } - } - } - if err := scanner.Err(); err != nil { - return "", "", err - } - - return "", "", NewNotFoundError(subsystem) -} - -func isSubsystemAvailable(subsystem string) bool { - if IsCgroup2UnifiedMode() { - panic("don't call isSubsystemAvailable from cgroupv2 code") - } - - cgroups, err := ParseCgroupFile("/proc/self/cgroup") - if err != nil { - return false - } - _, avail := cgroups[subsystem] - return avail -} - type Mount struct { Mountpoint string Root string Subsystems []string } -func (m Mount) GetOwnCgroup(cgroups map[string]string) (string, error) { - if len(m.Subsystems) == 0 { - return "", fmt.Errorf("no subsystem for mount") - } - - return getControllerPath(m.Subsystems[0], cgroups) -} - -func getCgroupMountsHelper(ss map[string]bool, mi io.Reader, all bool) ([]Mount, error) { - res := make([]Mount, 0, len(ss)) - scanner := bufio.NewScanner(mi) - numFound := 0 - for scanner.Scan() && numFound < len(ss) { - txt := scanner.Text() - sepIdx := strings.Index(txt, " - ") - if sepIdx == -1 { - return nil, fmt.Errorf("invalid mountinfo format") - } - if txt[sepIdx+3:sepIdx+10] == "cgroup2" || txt[sepIdx+3:sepIdx+9] != "cgroup" { - continue - } - fields := strings.Split(txt, " ") - m := Mount{ - Mountpoint: fields[4], - Root: fields[3], - } - for _, opt := range strings.Split(fields[len(fields)-1], ",") { - seen, known := ss[opt] - if !known || (!all && seen) { - continue - } - ss[opt] = true - if strings.HasPrefix(opt, CgroupNamePrefix) { - opt = opt[len(CgroupNamePrefix):] - } - m.Subsystems = append(m.Subsystems, opt) - numFound++ - } - if len(m.Subsystems) > 0 || all { - res = append(res, m) - } - } - if err := scanner.Err(); err != nil { - return nil, err - } - return res, nil -} - // GetCgroupMounts returns the mounts for the cgroup subsystems. // all indicates whether to return just the first instance or all the mounts. // This function should not be used from cgroupv2 code, as in this case @@ -193,25 +76,6 @@ func GetCgroupMounts(all bool) ([]Mount, error) { return getCgroupMountsV1(all) } -func getCgroupMountsV1(all bool) ([]Mount, error) { - f, err := os.Open("/proc/self/mountinfo") - if err != nil { - return nil, err - } - defer f.Close() - - allSubsystems, err := ParseCgroupFile("/proc/self/cgroup") - if err != nil { - return nil, err - } - - allMap := make(map[string]bool) - for s := range allSubsystems { - allMap[s] = false - } - return getCgroupMountsHelper(allMap, f, all) -} - // GetAllSubsystems returns all the cgroup subsystems supported by the kernel func GetAllSubsystems() ([]string, error) { // /proc/cgroups is meaningless for v2 @@ -253,65 +117,6 @@ func GetAllSubsystems() ([]string, error) { return subsystems, nil } -// GetOwnCgroup returns the relative path to the cgroup docker is running in. -func GetOwnCgroup(subsystem string) (string, error) { - if IsCgroup2UnifiedMode() { - return "", errUnified - } - cgroups, err := ParseCgroupFile("/proc/self/cgroup") - if err != nil { - return "", err - } - - return getControllerPath(subsystem, cgroups) -} - -func GetOwnCgroupPath(subsystem string) (string, error) { - cgroup, err := GetOwnCgroup(subsystem) - if err != nil { - return "", err - } - - return getCgroupPathHelper(subsystem, cgroup) -} - -func GetInitCgroup(subsystem string) (string, error) { - if IsCgroup2UnifiedMode() { - return "", errUnified - } - cgroups, err := ParseCgroupFile("/proc/1/cgroup") - if err != nil { - return "", err - } - - return getControllerPath(subsystem, cgroups) -} - -func GetInitCgroupPath(subsystem string) (string, error) { - cgroup, err := GetInitCgroup(subsystem) - if err != nil { - return "", err - } - - return getCgroupPathHelper(subsystem, cgroup) -} - -func getCgroupPathHelper(subsystem, cgroup string) (string, error) { - mnt, root, err := FindCgroupMountpointAndRoot("", subsystem) - if err != nil { - return "", err - } - - // This is needed for nested containers, because in /proc/self/cgroup we - // see paths from host, which don't exist in container. - relCgroup, err := filepath.Rel(root, cgroup) - if err != nil { - return "", err - } - - return filepath.Join(mnt, relCgroup), nil -} - func readProcsFile(file string) ([]int, error) { f, err := os.Open(file) if err != nil { @@ -384,22 +189,6 @@ func parseCgroupFromReader(r io.Reader) (map[string]string, error) { return cgroups, nil } -func getControllerPath(subsystem string, cgroups map[string]string) (string, error) { - if IsCgroup2UnifiedMode() { - return "", errUnified - } - - if p, ok := cgroups[subsystem]; ok { - return p, nil - } - - if p, ok := cgroups[CgroupNamePrefix+subsystem]; ok { - return p, nil - } - - return "", NewNotFoundError(subsystem) -} - func PathExists(path string) bool { if _, err := os.Stat(path); err != nil { return false diff --git a/libcontainer/cgroups/v1_utils.go b/libcontainer/cgroups/v1_utils.go new file mode 100644 index 00000000..e32c48a5 --- /dev/null +++ b/libcontainer/cgroups/v1_utils.go @@ -0,0 +1,252 @@ +package cgroups + +import ( + "bufio" + "errors" + "fmt" + "io" + "os" + "path/filepath" + "strings" +) + +// Code in this source file are specific to cgroup v1, +// and must not be used from any cgroup v2 code. + +const ( + CgroupNamePrefix = "name=" +) + +var ( + errUnified = errors.New("not implemented for cgroup v2 unified hierarchy") +) + +type NotFoundError struct { + Subsystem string +} + +func (e *NotFoundError) Error() string { + return fmt.Sprintf("mountpoint for %s not found", e.Subsystem) +} + +func NewNotFoundError(sub string) error { + return &NotFoundError{ + Subsystem: sub, + } +} + +func IsNotFound(err error) bool { + if err == nil { + return false + } + _, ok := err.(*NotFoundError) + return ok +} + +// https://www.kernel.org/doc/Documentation/cgroup-v1/cgroups.txt +func FindCgroupMountpoint(cgroupPath, subsystem string) (string, error) { + if IsCgroup2UnifiedMode() { + return "", errUnified + } + mnt, _, err := FindCgroupMountpointAndRoot(cgroupPath, subsystem) + return mnt, err +} + +func FindCgroupMountpointAndRoot(cgroupPath, subsystem string) (string, string, error) { + if IsCgroup2UnifiedMode() { + return "", "", errUnified + } + + // We are not using mount.GetMounts() because it's super-inefficient, + // parsing it directly sped up x10 times because of not using Sscanf. + // It was one of two major performance drawbacks in container start. + if !isSubsystemAvailable(subsystem) { + return "", "", NewNotFoundError(subsystem) + } + + f, err := os.Open("/proc/self/mountinfo") + if err != nil { + return "", "", err + } + defer f.Close() + + return findCgroupMountpointAndRootFromReader(f, cgroupPath, subsystem) +} + +func findCgroupMountpointAndRootFromReader(reader io.Reader, cgroupPath, subsystem string) (string, string, error) { + scanner := bufio.NewScanner(reader) + for scanner.Scan() { + txt := scanner.Text() + fields := strings.Fields(txt) + if len(fields) < 9 { + continue + } + if strings.HasPrefix(fields[4], cgroupPath) { + for _, opt := range strings.Split(fields[len(fields)-1], ",") { + if opt == subsystem { + return fields[4], fields[3], nil + } + } + } + } + if err := scanner.Err(); err != nil { + return "", "", err + } + + return "", "", NewNotFoundError(subsystem) +} + +func isSubsystemAvailable(subsystem string) bool { + if IsCgroup2UnifiedMode() { + panic("don't call isSubsystemAvailable from cgroupv2 code") + } + + cgroups, err := ParseCgroupFile("/proc/self/cgroup") + if err != nil { + return false + } + _, avail := cgroups[subsystem] + return avail +} + +func (m Mount) GetOwnCgroup(cgroups map[string]string) (string, error) { + if len(m.Subsystems) == 0 { + return "", fmt.Errorf("no subsystem for mount") + } + + return getControllerPath(m.Subsystems[0], cgroups) +} + +func getCgroupMountsHelper(ss map[string]bool, mi io.Reader, all bool) ([]Mount, error) { + res := make([]Mount, 0, len(ss)) + scanner := bufio.NewScanner(mi) + numFound := 0 + for scanner.Scan() && numFound < len(ss) { + txt := scanner.Text() + sepIdx := strings.Index(txt, " - ") + if sepIdx == -1 { + return nil, fmt.Errorf("invalid mountinfo format") + } + if txt[sepIdx+3:sepIdx+10] == "cgroup2" || txt[sepIdx+3:sepIdx+9] != "cgroup" { + continue + } + fields := strings.Split(txt, " ") + m := Mount{ + Mountpoint: fields[4], + Root: fields[3], + } + for _, opt := range strings.Split(fields[len(fields)-1], ",") { + seen, known := ss[opt] + if !known || (!all && seen) { + continue + } + ss[opt] = true + if strings.HasPrefix(opt, CgroupNamePrefix) { + opt = opt[len(CgroupNamePrefix):] + } + m.Subsystems = append(m.Subsystems, opt) + numFound++ + } + if len(m.Subsystems) > 0 || all { + res = append(res, m) + } + } + if err := scanner.Err(); err != nil { + return nil, err + } + return res, nil +} + +func getCgroupMountsV1(all bool) ([]Mount, error) { + f, err := os.Open("/proc/self/mountinfo") + if err != nil { + return nil, err + } + defer f.Close() + + allSubsystems, err := ParseCgroupFile("/proc/self/cgroup") + if err != nil { + return nil, err + } + + allMap := make(map[string]bool) + for s := range allSubsystems { + allMap[s] = false + } + return getCgroupMountsHelper(allMap, f, all) +} + +// GetOwnCgroup returns the relative path to the cgroup docker is running in. +func GetOwnCgroup(subsystem string) (string, error) { + if IsCgroup2UnifiedMode() { + return "", errUnified + } + cgroups, err := ParseCgroupFile("/proc/self/cgroup") + if err != nil { + return "", err + } + + return getControllerPath(subsystem, cgroups) +} + +func GetOwnCgroupPath(subsystem string) (string, error) { + cgroup, err := GetOwnCgroup(subsystem) + if err != nil { + return "", err + } + + return getCgroupPathHelper(subsystem, cgroup) +} + +func GetInitCgroup(subsystem string) (string, error) { + if IsCgroup2UnifiedMode() { + return "", errUnified + } + cgroups, err := ParseCgroupFile("/proc/1/cgroup") + if err != nil { + return "", err + } + + return getControllerPath(subsystem, cgroups) +} + +func GetInitCgroupPath(subsystem string) (string, error) { + cgroup, err := GetInitCgroup(subsystem) + if err != nil { + return "", err + } + + return getCgroupPathHelper(subsystem, cgroup) +} + +func getCgroupPathHelper(subsystem, cgroup string) (string, error) { + mnt, root, err := FindCgroupMountpointAndRoot("", subsystem) + if err != nil { + return "", err + } + + // This is needed for nested containers, because in /proc/self/cgroup we + // see paths from host, which don't exist in container. + relCgroup, err := filepath.Rel(root, cgroup) + if err != nil { + return "", err + } + + return filepath.Join(mnt, relCgroup), nil +} + +func getControllerPath(subsystem string, cgroups map[string]string) (string, error) { + if IsCgroup2UnifiedMode() { + return "", errUnified + } + + if p, ok := cgroups[subsystem]; ok { + return p, nil + } + + if p, ok := cgroups[CgroupNamePrefix+subsystem]; ok { + return p, nil + } + + return "", NewNotFoundError(subsystem) +}