libct: unify IOPriority setting

For some reason, io priority is set in different places between runc
start/run and runc exec (it is done much earlier for the latter).

Let's unify the code flow of start/run and exec.

Signed-off-by: Kir Kolyshkin <[email protected]>

libcontainer/init_linux.go

@@ -692,6 +692,27 @@ func setupScheduler(config *configs.Config) error {
  return nil
 }
 
+func setIOPriority(ioprio *configs.IOPriority) error {
+ const ioprioWhoPgrp = 1
+
+ if ioprio == nil {
+ return nil
+ }
+ class, ok := configs.IOPrioClassMapping[ioprio.Class]
+ if !ok {
+ return fmt.Errorf("invalid io priority class: %s", ioprio.Class)
+ }
+
+ // Combine class and priority into a single value
+ // https://github.com/torvalds/linux/blob/v5.18/include/uapi/linux/ioprio.h#L5-L17
+ iop := (class << 13) | ioprio.Priority
+ _, _, errno := unix.RawSyscall(unix.SYS_IOPRIO_SET, ioprioWhoPgrp, 0, uintptr(iop))
+ if errno != 0 {
+ return fmt.Errorf("failed to set io priority: %w", errno)
+ }
+ return nil
+}
+
 func setupPersonality(config *configs.Config) error {
  return system.SetLinuxPersonality(config.Personality.Domain)
 }

libcontainer/process_linux.go

@@ -125,10 +125,6 @@ func (p *setnsProcess) signal(sig os.Signal) error {
 func (p *setnsProcess) start() (retErr error) {
  defer p.comm.closeParent()
 
- if err := setIOPriority(p.process.IOPriority); err != nil {
- return err
- }
-
  // get the "before" value of oom kill count
  oom, _ := p.manager.OOMKillCount()
  err := p.cmd.Start()
@@ -986,24 +982,3 @@ func initWaiter(r io.Reader) chan error {
 
  return ch
 }
-
-func setIOPriority(ioprio *configs.IOPriority) error {
- const ioprioWhoPgrp = 1
-
- if ioprio == nil {
- return nil
- }
- class, ok := configs.IOPrioClassMapping[ioprio.Class]
- if !ok {
- return fmt.Errorf("invalid io priority class: %s", ioprio.Class)
- }
-
- // Combine class and priority into a single value
- // https://github.com/torvalds/linux/blob/v5.18/include/uapi/linux/ioprio.h#L5-L17
- iop := (class << 13) | ioprio.Priority
- _, _, errno := unix.RawSyscall(unix.SYS_IOPRIO_SET, ioprioWhoPgrp, 0, uintptr(iop))
- if errno != 0 {
- return fmt.Errorf("failed to set io priority: %w", errno)
- }
- return nil
-}

libcontainer/setns_init_linux.go

@@ -76,6 +76,9 @@ func (l *linuxSetnsInit) Init() error {
  return err
  }
 
+ if err := setIOPriority(l.config.Config.IOPriority); err != nil {
+ return err
+ }
  // Tell our parent that we're ready to exec. This must be done before the
  // Seccomp rules have been applied, because we need to be able to read and
  // write to a socket.