vzctl start: fix exit code if ioprio set failed

Return code from ve_ioprio_set() is propagated all the way up to main()
and is used as vzctl exit code:
main()
  run_action()
    start()
      vps_start()
        vps_start_custom()
          vps_setup_res()
            ve_ioprio_set()

So we ended up exiting with -1 (255) from vzctl if ioprio set failed.

Fix it by introducing VZ_IO_SET. Document it in vzctl(8) man page.

Signed-off-by: Kir Kolyshkin <kir@openvz.org>
3 files changed