Revert "UBUNTU: SAUCE: (noup) cgroup namespaces: add a 'nsroot=' mountinfo field"

BugLink: http://bugs.launchpad.net/bugs/1584163

This reverts commit d5e333e3.

Cc: Serge Hallyn <serge.hallyn@ubuntu.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>

fs/kernfs/mount.c

@@ -36,7 +36,7 @@ static int kernfs_sop_show_options(struct seq_file *sf, struct dentry *dentry)
 	struct kernfs_syscall_ops *scops = root->syscall_ops;
 
 	if (scops && scops->show_options)
-		return scops->show_options(sf, dentry, root);
+		return scops->show_options(sf, root);
 	return 0;
 }
 

include/linux/kernfs.h

@@ -145,8 +145,7 @@ struct kernfs_node {
  */
 struct kernfs_syscall_ops {
 	int (*remount_fs)(struct kernfs_root *root, int *flags, char *data);
-	int (*show_options)(struct seq_file *sf, struct dentry *dentry,
-			    struct kernfs_root *root);
+	int (*show_options)(struct seq_file *sf, struct kernfs_root *root);
 
 	int (*mkdir)(struct kernfs_node *parent, const char *name,
 		     umode_t mode);

kernel/cgroup.c

@@ -1589,32 +1589,7 @@ static int rebind_subsystems(struct cgroup_root *dst_root,
 	return 0;
 }
 
-static void cgroup_show_nsroot(struct seq_file *seq, struct dentry *dentry,
-			       struct kernfs_root *kf_root)
-{
-	struct kernfs_node *d_kn = dentry->d_fsdata;
-	char *nsroot;
-	int len, ret;
-
-	if (!kf_root)
-		return;
-	len = kernfs_path_from_node(d_kn, kf_root->kn, NULL, 0);
-	if (len <= 0)
-		return;
-	nsroot = kzalloc(len + 1, GFP_ATOMIC);
-	if (!nsroot)
-		return;
-	ret = kernfs_path_from_node(d_kn, kf_root->kn, nsroot, len + 1);
-	if (ret <= 0 || ret > len)
-		goto out;
-
-	seq_show_option(seq, "nsroot", nsroot);
-
-out:
-	kfree(nsroot);
-}
-
-static int cgroup_show_options(struct seq_file *seq, struct dentry *dentry,
+static int cgroup_show_options(struct seq_file *seq,
 			       struct kernfs_root *kf_root)
 {
 	struct cgroup_root *root = cgroup_root_from_kf(kf_root);
@@ -1640,8 +1615,6 @@ static int cgroup_show_options(struct seq_file *seq, struct dentry *dentry,
 		seq_puts(seq, ",clone_children");
 	if (strlen(root->name))
 		seq_show_option(seq, "name", root->name);
-	cgroup_show_nsroot(seq, dentry, kf_root);
-
 	return 0;
 }