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|
package fs2
import (
"fmt"
"os"
"path/filepath"
"strings"
"github.com/opencontainers/cgroups"
)
func supportedControllers() (string, error) {
return cgroups.ReadFile(UnifiedMountpoint, "/cgroup.controllers")
}
// needAnyControllers returns whether we enable some supported controllers or not,
// based on (1) controllers available and (2) resources that are being set.
// We don't check "pseudo" controllers such as
// "freezer" and "devices".
func needAnyControllers(r *cgroups.Resources) (bool, error) {
if r == nil {
return false, nil
}
// list of all available controllers
content, err := supportedControllers()
if err != nil {
return false, err
}
avail := make(map[string]struct{})
for _, ctr := range strings.Fields(content) {
avail[ctr] = struct{}{}
}
// check whether the controller if available or not
have := func(controller string) bool {
_, ok := avail[controller]
return ok
}
if isPidsSet(r) && have("pids") {
return true, nil
}
if isMemorySet(r) && have("memory") {
return true, nil
}
if isIoSet(r) && have("io") {
return true, nil
}
if isCPUSet(r) && have("cpu") {
return true, nil
}
if isCpusetSet(r) && have("cpuset") {
return true, nil
}
if isHugeTlbSet(r) && have("hugetlb") {
return true, nil
}
return false, nil
}
// containsDomainController returns whether the current config contains domain controller or not.
// Refer to: http://man7.org/linux/man-pages/man7/cgroups.7.html
// As at Linux 4.19, the following controllers are threaded: cpu, perf_event, and pids.
func containsDomainController(r *cgroups.Resources) bool {
return isMemorySet(r) || isIoSet(r) || isCPUSet(r) || isHugeTlbSet(r)
}
// CreateCgroupPath creates cgroupv2 path, enabling all the supported controllers.
func CreateCgroupPath(path string, c *cgroups.Cgroup) (Err error) {
if !strings.HasPrefix(path, UnifiedMountpoint) {
return fmt.Errorf("invalid cgroup path %s", path)
}
content, err := supportedControllers()
if err != nil {
return err
}
const (
cgTypeFile = "cgroup.type"
cgStCtlFile = "cgroup.subtree_control"
)
ctrs := strings.Fields(content)
res := "+" + strings.Join(ctrs, " +")
elements := strings.Split(path, "/")
elements = elements[3:]
current := "/sys/fs"
for i, e := range elements {
current = filepath.Join(current, e)
if i > 0 {
if err := os.Mkdir(current, 0o755); err != nil {
if !os.IsExist(err) {
return err
}
} else {
// If the directory was created, be sure it is not left around on errors.
current := current
defer func() {
if Err != nil {
os.Remove(current)
}
}()
}
cgType, _ := cgroups.ReadFile(current, cgTypeFile)
cgType = strings.TrimSpace(cgType)
switch cgType {
// If the cgroup is in an invalid mode (usually this means there's an internal
// process in the cgroup tree, because we created a cgroup under an
// already-populated-by-other-processes cgroup), then we have to error out if
// the user requested controllers which are not thread-aware. However, if all
// the controllers requested are thread-aware we can simply put the cgroup into
// threaded mode.
case "domain invalid":
if containsDomainController(c.Resources) {
return fmt.Errorf("cannot enter cgroupv2 %q with domain controllers -- it is in an invalid state", current)
} else {
// Not entirely correct (in theory we'd always want to be a domain --
// since that means we're a properly delegated cgroup subtree) but in
// this case there's not much we can do and it's better than giving an
// error.
_ = cgroups.WriteFile(current, cgTypeFile, "threaded")
}
// If the cgroup is in (threaded) or (domain threaded) mode, we can only use thread-aware controllers
// (and you cannot usually take a cgroup out of threaded mode).
case "domain threaded":
fallthrough
case "threaded":
if containsDomainController(c.Resources) {
return fmt.Errorf("cannot enter cgroupv2 %q with domain controllers -- it is in %s mode", current, cgType)
}
}
}
// enable all supported controllers
if i < len(elements)-1 {
if err := cgroups.WriteFile(current, cgStCtlFile, res); err != nil {
// try write one by one
allCtrs := strings.Split(res, " ")
for _, ctr := range allCtrs {
_ = cgroups.WriteFile(current, cgStCtlFile, ctr)
}
}
// Some controllers might not be enabled when rootless or containerized,
// but we don't catch the error here. (Caught in setXXX() functions.)
}
}
return nil
}
|
