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SubjectRe: [PATCH 1/2] fs/lock: skip lock owner pid translation in case we are in init_pid_ns
On Fri, Jun 08, 2018 at 05:27:11PM +0300, Konstantin Khorenko wrote:
> If the flock owner process is dead and its pid has been already freed,
> pid translation won't work, but we still want to show flock owner pid
> number when expecting /proc/$PID/fdinfo/$FD in init pidns.
>
> Reproducer:
> process A process A1 process A2
> fork()--------->
> exit() open()
> flock()
> fork()--------->
> exit() sleep()
>
> Before the patch:
> ================
> (root@vz7)/: cat /proc/${PID_A2}/fdinfo/3
> pos: 4
> flags: 02100002
> mnt_id: 257
> lock: (root@vz7)/:
>
> After the patch:
> ===============
> (root@vz7)/:cat /proc/${PID_A2}/fdinfo/3
> pos: 4
> flags: 02100002
> mnt_id: 295
> lock: 1: FLOCK ADVISORY WRITE ${PID_A1} b6:f8a61:529946 0 EOF
>

Acked-by: Andrey Vagin <avagin@openvz.org>

> Fixes: 9d5b86ac13c5 ("fs/locks: Remove fl_nspid and use fs-specific l_pid for remote locks")
> Signed-off-by: Konstantin Khorenko <khorenko@virtuozzo.com>
> ---
> fs/locks.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/fs/locks.c b/fs/locks.c
> index 05e211be8684..bfee5b7f2862 100644
> --- a/fs/locks.c
> +++ b/fs/locks.c
> @@ -2072,6 +2072,13 @@ static pid_t locks_translate_pid(struct file_lock *fl, struct pid_namespace *ns)
> return -1;
> if (IS_REMOTELCK(fl))
> return fl->fl_pid;
> + /*
> + * If the flock owner process is dead and its pid has been already
> + * freed, the translation below won't work, but we still want to show
> + * flock owner pid number in init pidns.
> + */
> + if (ns == &init_pid_ns)
> + return (pid_t)fl->fl_pid;
>
> rcu_read_lock();
> pid = find_pid_ns(fl->fl_pid, &init_pid_ns);
> --
> 2.15.1
>

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