[CRIU] [PATCH 14/21] ns: Collect/read pid_for_children ns

[Kirill Tkhai]

Handle it as other namespaces, except of case of
just unshared pid ns w/o child reaper (fail if so),
and in case of we don't have it on restore (old
images -- then get pid_for_children ns from pid ns).

Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
---
 criu/include/pstree.h |    1 +
 criu/namespaces.c     |   22 ++++++++++++++++++++++
 criu/pstree.c         |   15 +++++++++++++++
 3 files changed, 38 insertions(+)

diff --git a/criu/include/pstree.h b/criu/include/pstree.h
index 892a1cd62..c906ec1a9 100644
--- a/criu/include/pstree.h
+++ b/criu/include/pstree.h
@@ -139,6 +139,7 @@ extern int pstree_alloc_cores(struct pstree_item *item);
 extern void pstree_free_cores(struct pstree_item *item);
 
 extern int collect_pstree_ids(void);
+extern int fixup_pid_for_children_ns(TaskKobjIdsEntry *ids);
 
 extern int preorder_pstree_traversal(struct pstree_item *item, int (*f)(struct pstree_item *));
 extern int __set_next_pid(pid_t pid);
diff --git a/criu/namespaces.c b/criu/namespaces.c
index 94f9140cc..880da2836 100644
--- a/criu/namespaces.c
+++ b/criu/namespaces.c
@@ -684,6 +684,25 @@ struct collect_image_info nsfile_cinfo = {
 	.collect = collect_one_nsfile,
 };
 
+static int get_pid_for_children_ns_id(pid_t pid, TaskKobjIdsEntry *ids)
+{
+	ids->has_pid_for_children_ns_id = false;
+
+	if (kdat.has_pid_for_children_ns) {
+		ids->pid_for_children_ns_id = __get_ns_id(pid, &pid_ns_desc, true,
+							  &ids->has_pid_for_children_ns_id, NULL);
+		if (!ids->pid_for_children_ns_id) {
+			pr_err("Can't make pid_for_children id\n");
+			return -1;
+		}
+		if (ids->pid_for_children_ns_id == UINT_MAX) {
+			pr_err("Just unshared pid namespaces are not supported yet\n");
+			return -1;
+		}
+	}
+	return 0;
+}
+
 /*
  * Same as dump_task_ns_ids(), but
  * a) doesn't keep IDs (don't need them)
@@ -769,6 +788,9 @@ int dump_task_ns_ids(struct pstree_item *item)
 		return -1;
 	}
 
+	if (get_pid_for_children_ns_id(pid, ids) < 0)
+		return -1;
+
 	return 0;
 }
 
diff --git a/criu/pstree.c b/criu/pstree.c
index f33da75a9..529505f29 100644
--- a/criu/pstree.c
+++ b/criu/pstree.c
@@ -616,6 +616,18 @@ struct pid *__pstree_pid_by_virt(struct ns_id *ns, pid_t pid)
 	return NULL;
 }
 
+int fixup_pid_for_children_ns(TaskKobjIdsEntry *ids)
+{
+	if (!ids->has_pid_for_children_ns_id) {
+		ids->has_pid_for_children_ns_id = true;
+		ids->pid_for_children_ns_id = ids->pid_ns_id;
+	} else if (!lookup_ns_by_id(ids->pid_for_children_ns_id, &pid_ns_desc)) {
+		pr_err("Can't find pid_for_children ns linked\n");
+		return -1;
+	}
+	return 0;
+}
+
 static int read_pstree_ids(pid_t pid, TaskKobjIdsEntry **ids)
 {
 	struct cr_img *img;
@@ -660,6 +672,9 @@ static int read_pstree_ids(pid_t pid, TaskKobjIdsEntry **ids)
 			ret = -1;
 	}
 
+	if (!ret)
+		ret = fixup_pid_for_children_ns(*ids);
+
 	if (!ret && !top_pid_ns) {
 		/*
 		 * If top_pid_ns is not set, this means that here is old dump,