[bug#40871] [PATCH] file-systems: mount the PID cgroup filesystem.

["Jakub Kądziołka" <kuba@kadziolka.net>]

* gnu/system/file-systems.scm (%control-groups): Add "pids".
* gnu/services/docker.scm (docker-shepherd-service): Resolve a TODO.

This has allowed me to make a specific configuration of nsjail work.
---
 gnu/services/docker.scm     | 3 ++-
 gnu/system/file-systems.scm | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/gnu/services/docker.scm b/gnu/services/docker.scm
index 04f9127346..d6dc792821 100644
--- a/gnu/services/docker.scm
+++ b/gnu/services/docker.scm
@@ -1,5 +1,6 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2018 Danny Milosavljevic <dannym@scratchpost.org>
+;;; Copyright © 2020 Jakub Kądziołka <kuba@kadziolka.net>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -94,7 +95,7 @@ loop-back communications.")
                           file-system-/sys/fs/cgroup/cpuset
                           file-system-/sys/fs/cgroup/devices
                           file-system-/sys/fs/cgroup/memory
-                          ; TODO: file-system-/sys/fs/cgroup/pids
+                          file-system-/sys/fs/cgroup/pids
                           networking
                           udev))
            (start #~(make-forkexec-constructor
diff --git a/gnu/system/file-systems.scm b/gnu/system/file-systems.scm
index 3b599efa8e..b41f66e943 100644
--- a/gnu/system/file-systems.scm
+++ b/gnu/system/file-systems.scm
@@ -1,5 +1,6 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2013, 2014, 2015, 2016, 2017, 2018, 2019 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2020 Jakub Kądziołka <kuba@kadziolka.net>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -389,7 +390,7 @@ TARGET in the other system."
                    ;; parent directory.
                    (dependencies (list parent))))
                '("cpuset" "cpu" "cpuacct" "memory" "devices" "freezer"
-                 "blkio" "perf_event")))))
+                 "blkio" "perf_event" "pids")))))
 
 (define %elogind-file-systems
   ;; We don't use systemd, but these file systems are needed for elogind,
-- 
2.26.0