[PATCH v4 18/72] nstree: add unified namespace list

[Christian Brauner <brauner@kernel.org>]

Allow to walk the unified namespace list completely locklessly.

Signed-off-by: Christian Brauner <brauner@kernel.org>
---
 fs/namespace.c           |  1 +
 init/version-timestamp.c |  1 +
 ipc/msgutil.c            |  1 +
 kernel/cgroup/cgroup.c   |  1 +
 kernel/nscommon.c        |  1 +
 kernel/nstree.c          | 13 ++++++++++++-
 kernel/pid.c             |  1 +
 kernel/time/namespace.c  |  1 +
 kernel/user.c            |  1 +
 9 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/fs/namespace.c b/fs/namespace.c
index 3e0361c4c138..1cb4cc8f7f5f 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -5995,6 +5995,7 @@ struct mnt_namespace init_mnt_ns = {
 	.mounts		= RB_ROOT,
 	.poll		= __WAIT_QUEUE_HEAD_INITIALIZER(init_mnt_ns.poll),
 	.ns.ns_list_node = LIST_HEAD_INIT(init_mnt_ns.ns.ns_list_node),
+	.ns.ns_unified_list_node = LIST_HEAD_INIT(init_mnt_ns.ns.ns_unified_list_node),
 	.ns.ns_owner_entry = LIST_HEAD_INIT(init_mnt_ns.ns.ns_owner_entry),
 	.ns.ns_owner = LIST_HEAD_INIT(init_mnt_ns.ns.ns_owner),
 };
diff --git a/init/version-timestamp.c b/init/version-timestamp.c
index e5c278dabecf..cd6f435d5fde 100644
--- a/init/version-timestamp.c
+++ b/init/version-timestamp.c
@@ -22,6 +22,7 @@ struct uts_namespace init_uts_ns = {
 	.user_ns = &init_user_ns,
 	.ns.inum = ns_init_inum(&init_uts_ns),
 	.ns.ns_list_node = LIST_HEAD_INIT(init_uts_ns.ns.ns_list_node),
+	.ns.ns_unified_list_node = LIST_HEAD_INIT(init_uts_ns.ns.ns_unified_list_node),
 	.ns.ns_owner_entry = LIST_HEAD_INIT(init_uts_ns.ns.ns_owner_entry),
 	.ns.ns_owner = LIST_HEAD_INIT(init_uts_ns.ns.ns_owner),
 #ifdef CONFIG_UTS_NS
diff --git a/ipc/msgutil.c b/ipc/msgutil.c
index ce1de73725c0..3708f325228d 100644
--- a/ipc/msgutil.c
+++ b/ipc/msgutil.c
@@ -32,6 +32,7 @@ struct ipc_namespace init_ipc_ns = {
 	.user_ns = &init_user_ns,
 	.ns.inum = ns_init_inum(&init_ipc_ns),
 	.ns.ns_list_node = LIST_HEAD_INIT(init_ipc_ns.ns.ns_list_node),
+	.ns.ns_unified_list_node = LIST_HEAD_INIT(init_ipc_ns.ns.ns_unified_list_node),
 	.ns.ns_owner_entry = LIST_HEAD_INIT(init_ipc_ns.ns.ns_owner_entry),
 	.ns.ns_owner = LIST_HEAD_INIT(init_ipc_ns.ns.ns_owner),
 #ifdef CONFIG_IPC_NS
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 9fa082e2eb1a..a0eee0785080 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -258,6 +258,7 @@ struct cgroup_namespace init_cgroup_ns = {
 	.root_cset	= &init_css_set,
 	.ns.ns_type	= ns_common_type(&init_cgroup_ns),
 	.ns.ns_list_node = LIST_HEAD_INIT(init_cgroup_ns.ns.ns_list_node),
+	.ns.ns_unified_list_node = LIST_HEAD_INIT(init_cgroup_ns.ns.ns_unified_list_node),
 	.ns.ns_owner_entry = LIST_HEAD_INIT(init_cgroup_ns.ns.ns_owner_entry),
 	.ns.ns_owner = LIST_HEAD_INIT(init_cgroup_ns.ns.ns_owner),
 };
diff --git a/kernel/nscommon.c b/kernel/nscommon.c
index bd4cf8bb8a77..affaf91c2074 100644
--- a/kernel/nscommon.c
+++ b/kernel/nscommon.c
@@ -64,6 +64,7 @@ int __ns_common_init(struct ns_common *ns, u32 ns_type, const struct proc_ns_ope
 	RB_CLEAR_NODE(&ns->ns_unified_tree_node);
 	RB_CLEAR_NODE(&ns->ns_owner_tree_node);
 	INIT_LIST_HEAD(&ns->ns_list_node);
+	INIT_LIST_HEAD(&ns->ns_unified_list_node);
 	ns->ns_owner_tree = RB_ROOT;
 	INIT_LIST_HEAD(&ns->ns_owner);
 	INIT_LIST_HEAD(&ns->ns_owner_entry);
diff --git a/kernel/nstree.c b/kernel/nstree.c
index 1779fa314a7d..100145e5edd1 100644
--- a/kernel/nstree.c
+++ b/kernel/nstree.c
@@ -8,6 +8,7 @@
 
 __cacheline_aligned_in_smp DEFINE_SEQLOCK(ns_tree_lock);
 static struct rb_root ns_unified_tree = RB_ROOT; /* protected by ns_tree_lock */
+static LIST_HEAD(ns_unified_list); /* protected by ns_tree_lock */
 
 /**
  * struct ns_tree - Namespace tree
@@ -154,7 +155,13 @@ void __ns_tree_add_raw(struct ns_common *ns, struct ns_tree *ns_tree)
 	else
 		list_add_rcu(&ns->ns_list_node, &node_to_ns(prev)->ns_list_node);
 
+	/* Add to unified tree and list */
 	rb_find_add_rcu(&ns->ns_unified_tree_node, &ns_unified_tree, ns_cmp_unified);
+	prev = rb_prev(&ns->ns_unified_tree_node);
+	if (!prev)
+		list_add_rcu(&ns->ns_unified_list_node, &ns_unified_list);
+	else
+		list_add_rcu(&ns->ns_unified_list_node, &node_to_ns_unified(prev)->ns_unified_list_node);
 
 	if (ops) {
 		struct user_namespace *user_ns;
@@ -203,11 +210,15 @@ void __ns_tree_remove(struct ns_common *ns, struct ns_tree *ns_tree)
 
 	write_seqlock(&ns_tree_lock);
 	rb_erase(&ns->ns_tree_node, &ns_tree->ns_tree);
-	rb_erase(&ns->ns_unified_tree_node, &ns_unified_tree);
 	RB_CLEAR_NODE(&ns->ns_tree_node);
 
 	list_bidir_del_rcu(&ns->ns_list_node);
 
+	rb_erase(&ns->ns_unified_tree_node, &ns_unified_tree);
+	RB_CLEAR_NODE(&ns->ns_unified_tree_node);
+
+	list_bidir_del_rcu(&ns->ns_unified_list_node);
+
 	/* Remove from owner's rbtree if this namespace has an owner */
 	if (ops) {
 		user_ns = ops->owner(ns);
diff --git a/kernel/pid.c b/kernel/pid.c
index 8134c40b2584..22a0440a62fa 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -80,6 +80,7 @@ struct pid_namespace init_pid_ns = {
 	.user_ns = &init_user_ns,
 	.ns.inum = ns_init_inum(&init_pid_ns),
 	.ns.ns_list_node = LIST_HEAD_INIT(init_pid_ns.ns.ns_list_node),
+	.ns.ns_unified_list_node = LIST_HEAD_INIT(init_pid_ns.ns.ns_unified_list_node),
 	.ns.ns_owner_entry = LIST_HEAD_INIT(init_pid_ns.ns.ns_owner_entry),
 	.ns.ns_owner = LIST_HEAD_INIT(init_pid_ns.ns.ns_owner),
 #ifdef CONFIG_PID_NS
diff --git a/kernel/time/namespace.c b/kernel/time/namespace.c
index f543c4a83229..6a41269b1a5d 100644
--- a/kernel/time/namespace.c
+++ b/kernel/time/namespace.c
@@ -488,6 +488,7 @@ struct time_namespace init_time_ns = {
 	.ns.ns_owner = LIST_HEAD_INIT(init_time_ns.ns.ns_owner),
 	.frozen_offsets	= true,
 	.ns.ns_list_node = LIST_HEAD_INIT(init_time_ns.ns.ns_list_node),
+	.ns.ns_unified_list_node = LIST_HEAD_INIT(init_time_ns.ns.ns_unified_list_node),
 };
 
 void __init time_ns_init(void)
diff --git a/kernel/user.c b/kernel/user.c
index e392768ccd44..68fe16617d38 100644
--- a/kernel/user.c
+++ b/kernel/user.c
@@ -72,6 +72,7 @@ struct user_namespace init_user_ns = {
 	.group = GLOBAL_ROOT_GID,
 	.ns.inum = ns_init_inum(&init_user_ns),
 	.ns.ns_list_node = LIST_HEAD_INIT(init_user_ns.ns.ns_list_node),
+	.ns.ns_unified_list_node = LIST_HEAD_INIT(init_user_ns.ns.ns_unified_list_node),
 	.ns.ns_owner_entry = LIST_HEAD_INIT(init_user_ns.ns.ns_owner_entry),
 	.ns.ns_owner = LIST_HEAD_INIT(init_user_ns.ns.ns_owner),
 #ifdef CONFIG_USER_NS

-- 
2.47.3