make mntns ->get()/->put()/->install()/->inum() work with &mnt_ns->ns

Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/namespace.c b/fs/namespace.c
index adc2ea2..5c21fda 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1582,6 +1582,11 @@ static bool is_mnt_ns_file(struct dentry *dentry)
        return true;
 }
 
+struct mnt_namespace *to_mnt_ns(struct ns_common *ns)
+{
+       return container_of(ns, struct mnt_namespace, ns);
+}
+
 static bool mnt_ns_loop(struct dentry *dentry)
 {
        /* Could bind mounting the mount namespace inode cause a
@@ -1591,7 +1596,7 @@ static bool mnt_ns_loop(struct dentry *dentry)
        if (!is_mnt_ns_file(dentry))
                return false;
 
-       mnt_ns = get_proc_ns(dentry->d_inode)->ns;
+       mnt_ns = to_mnt_ns(get_proc_ns(dentry->d_inode)->ns);
        return current->nsproxy->mnt_ns->seq >= mnt_ns->seq;
 }
 
@@ -3146,14 +3151,14 @@ found:
 
 static void *mntns_get(struct task_struct *task)
 {
-       struct mnt_namespace *ns = NULL;
+       struct ns_common *ns = NULL;
        struct nsproxy *nsproxy;
 
        task_lock(task);
        nsproxy = task->nsproxy;
        if (nsproxy) {
-               ns = nsproxy->mnt_ns;
-               get_mnt_ns(ns);
+               ns = &nsproxy->mnt_ns->ns;
+               get_mnt_ns(to_mnt_ns(ns));
        }
        task_unlock(task);
 
@@ -3162,13 +3167,13 @@ static void *mntns_get(struct task_struct *task)
 
 static void mntns_put(void *ns)
 {
-       put_mnt_ns(ns);
+       put_mnt_ns(to_mnt_ns(ns));
 }
 
 static int mntns_install(struct nsproxy *nsproxy, void *ns)
 {
        struct fs_struct *fs = current->fs;
-       struct mnt_namespace *mnt_ns = ns;
+       struct mnt_namespace *mnt_ns = to_mnt_ns(ns);
        struct path root;
 
        if (!ns_capable(mnt_ns->user_ns, CAP_SYS_ADMIN) ||
@@ -3200,8 +3205,8 @@ static int mntns_install(struct nsproxy *nsproxy, void *ns)
 
 static unsigned int mntns_inum(void *ns)
 {
-       struct mnt_namespace *mnt_ns = ns;
-       return mnt_ns->ns.inum;
+       struct ns_common *p = ns;
+       return p->inum;
 }
 
 const struct proc_ns_operations mntns_operations = {