Commit 91e30cae authored Jun 08, 2018 by Konstantin Khorenko Committed by Greg Kroah-Hartman Oct 03, 2018

fs/lock: skip lock owner pid translation in case we are in init_pid_ns



[ Upstream commit 826d7bc9f013d01e92997883d2fd0c25f4af1f1c ]

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

Fixes: 9d5b86ac ("fs/locks: Remove fl_nspid and use fs-specific l_pid for remote locks")
Signed-off-by: Konstantin Khorenko <khorenko@virtuozzo.com>
Acked-by: Andrey Vagin <avagin@openvz.org>
Reviewed-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 0c4439c4

fs/locks.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -2074,6 +2074,13 @@ 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);