[Devel] [PATCH rh7 2/2] fs/lock: show locks taken by processes from another pidns

[Konstantin Khorenko]

Currently if we face a lock taken by a process invisible in the current
pidns we skip the lock completely, but this

1) makes the output not that nice
    (root at vz7)/: cat /proc/${PID_A2}/fdinfo/3
    pos:    4
    flags:  02100002
    mnt_id: 257
    lock:   (root at vz7)/:

2) makes it more difficult to debug issues with leaked flocks:
   imagine, you get error on lock, but don't see any locks in /proc/$id/fdinfo/$file

Let's show information about such locks again as previously, but
show zero in the owner pid field.

https://jira.sw.ru/browse/PSBM-85651

Signed-off-by: Konstantin Khorenko <khorenko at virtuozzo.com>
---
 fs/locks.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/fs/locks.c b/fs/locks.c
index 29650e7dcd64..3066d9e8f2d6 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -2539,12 +2539,10 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl,
 
 	fl_pid = locks_translate_pid(fl, proc_pidns);
 	/*
-	 * If there isn't a fl_pid don't display who is waiting on
-	 * the lock if we are called from locks_show, or if we are
-	 * called from __show_fd_info - skip lock entirely
+	 * If lock owner is dead (and pid is freed) or not visible in current
+	 * pidns, zero is shown as a pid value. Check lock info from
+	 * init_pid_ns to get saved lock pid value.
 	 */
-	if (fl_pid == 0)
-		return;
 
 	if (fl->fl_file != NULL)
 		inode = locks_inode(fl->fl_file);
-- 
2.15.1