logind: add infrastructure to keep track of machines, and move to slices

- This changes all logind cgroup objects to use slice objects rather
  than fixed croup locations.

- logind can now collect minimal information about running
  VMs/containers. As fixed cgroup locations can no longer be used we
  need an entity that keeps track of machine cgroups in whatever slice
  they might be located. Since logind already keeps track of users,
  sessions and seats this is a trivial addition.

- nspawn will now register with logind and pass various bits of metadata
  along. A new option "--slice=" has been added to place the container
  in a specific slice.

- loginctl gained commands to list, introspect and terminate machines.

- user.slice and machine.slice will now be pulled in by logind.service,
  since only logind.service requires this slice.

1 files changed, 19 insertions, 8 deletions

diff --git a/src/core/unit.c b/src/core/unit.c
index 90ff43da6..f75045dc4 100644
--- a/src/core/unit.c
+++ b/src/core/unit.c
@@ -672,7 +672,8 @@ void unit_dump(Unit *u, FILE *f, const char *prefix) {
                 "%s\tActive Exit Timestamp: %s\n"
                 "%s\tInactive Enter Timestamp: %s\n"
                 "%s\tGC Check Good: %s\n"
-                "%s\tNeed Daemon Reload: %s\n",
+                "%s\tNeed Daemon Reload: %s\n"
+                "%s\tSlice: %s\n",
                 prefix, u->id,
                 prefix, unit_description(u),
                 prefix, strna(u->instance),
@@ -683,7 +684,8 @@ void unit_dump(Unit *u, FILE *f, const char *prefix) {
                 prefix, strna(format_timestamp(timestamp3, sizeof(timestamp3), u->active_exit_timestamp.realtime)),
                 prefix, strna(format_timestamp(timestamp4, sizeof(timestamp4), u->inactive_enter_timestamp.realtime)),
                 prefix, yes_no(unit_check_gc(u)),
-                prefix, yes_no(unit_need_daemon_reload(u)));
+                prefix, yes_no(unit_need_daemon_reload(u)),
+                prefix, strna(unit_slice_name(u)));
 
         SET_FOREACH(t, u->names, i)
                 fprintf(f, "%s\tName: %s\n", prefix, t);
@@ -878,7 +880,7 @@ static int unit_add_default_dependencies(Unit *u) {
                                 return r;
                 }
 
-        if (u->default_dependencies && UNIT_DEREF(u->slice)) {
+        if (u->default_dependencies && UNIT_ISSET(u->slice)) {
                 r = unit_add_two_dependencies(u, UNIT_AFTER, UNIT_WANTS, UNIT_DEREF(u->slice), true);
                 if (r < 0)
                         return r;
@@ -1994,7 +1996,7 @@ char *unit_default_cgroup_path(Unit *u) {
 
         assert(u);
 
-        if (UNIT_DEREF(u->slice)) {
+        if (UNIT_ISSET(u->slice)) {
                 r = cg_slice_to_path(UNIT_DEREF(u->slice)->id, &slice);
                 if (r < 0)
                         return NULL;
@@ -2015,11 +2017,11 @@ char *unit_default_cgroup_path(Unit *u) {
                 if (!escaped_template)
                         return NULL;
 
-                return strjoin(u->manager->cgroup_hierarchy, "/",
+                return strjoin(u->manager->cgroup_root, "/",
                                slice ? slice : "", slice ? "/" : "",
                                escaped_template, "/", escaped_instance, NULL);
         } else
-                return strjoin(u->manager->cgroup_hierarchy, "/",
+                return strjoin(u->manager->cgroup_root, "/",
                                slice ? slice : "", slice ? "/" : "",
                                escaped_instance, NULL);
 }
@@ -2172,7 +2174,7 @@ int unit_add_default_slice(Unit *u) {
 
         assert(u);
 
-        if (UNIT_DEREF(u->slice))
+        if (UNIT_ISSET(u->slice))
                 return 0;
 
         if (u->manager->running_as != SYSTEMD_SYSTEM)
@@ -2186,6 +2188,15 @@ int unit_add_default_slice(Unit *u) {
         return 0;
 }
 
+const char *unit_slice_name(Unit *u) {
+        assert(u);
+
+        if (!UNIT_ISSET(u->slice))
+                return NULL;
+
+        return UNIT_DEREF(u->slice)->id;
+}
+
 int unit_add_default_cgroups(Unit *u) {
         CGroupAttribute *a;
         char **c;
@@ -2196,7 +2207,7 @@ int unit_add_default_cgroups(Unit *u) {
         /* Adds in the default cgroups, if they weren't specified
          * otherwise. */
 
-        if (!u->manager->cgroup_hierarchy)
+        if (!u->manager->cgroup_root)
                 return 0;
 
         r = unit_add_one_default_cgroup(u, NULL);