[PATCH 21/23] mnt: Add mount namespaces into ns_idr

[Kirill Tkhai]

Now they are exposed in /proc/namespace/ directory.

Signed-off-by: Kirill Tkhai <ktk...@virtuozzo.com>
---
 fs/mount.h     |    1 +
 fs/namespace.c |   10 +++++++++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/fs/mount.h b/fs/mount.h
index f296862032ec..cde7f7bed8ec 100644
--- a/fs/mount.h
+++ b/fs/mount.h
@@ -23,6 +23,7 @@ struct mnt_namespace {
        u64 event;
        unsigned int            mounts; /* # of mounts in the namespace */
        unsigned int            pending_mounts;
+       struct rcu_head         rcu;
 } __randomize_layout;
 
 struct mnt_pcp {
diff --git a/fs/namespace.c b/fs/namespace.c
index 8c39810e6ec3..756e43fd21f3 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -3258,7 +3258,7 @@ static void free_mnt_ns(struct mnt_namespace *ns)
                ns_free_inum(&ns->ns);
        dec_mnt_namespaces(ns->ucounts);
        put_user_ns(ns->user_ns);
-       kfree(ns);
+       kfree_rcu(ns, rcu);
 }
 
 /*
@@ -3382,6 +3382,12 @@ struct mnt_namespace *copy_mnt_ns(unsigned long flags, 
struct mnt_namespace *ns,
        if (pwdmnt)
                mntput(pwdmnt);
 
+       if (ns_idr_register(&new_ns->ns) < 0) {
+               drop_collected_mounts(&new_ns->root->mnt);
+               free_mnt_ns(new_ns);
+               new_ns = ERR_PTR(-ENOMEM);
+       }
+
        return new_ns;
 }
 
@@ -3824,6 +3830,7 @@ static void __init init_mount_tree(void)
        list_add(&m->mnt_list, &ns->list);
        init_task.nsproxy->mnt_ns = ns;
        get_mnt_ns(ns);
+       WARN_ON(ns_idr_register(&ns->ns) < 0);
 
        root.mnt = mnt;
        root.dentry = mnt->mnt_root;
@@ -3872,6 +3879,7 @@ void put_mnt_ns(struct mnt_namespace *ns)
 {
        if (!refcount_dec_and_test(&ns->ns.count))
                return;
+       ns_idr_unregister(&ns->ns);
        drop_collected_mounts(&ns->root->mnt);
        free_mnt_ns(ns);
 }