procfs: Don't cache a pid in the root inode.

Now that we have s_fs_info pointing to our pid namespace
the original reason for the proc root inode having a struct
pid is gone.

Caching a pid in the root inode has led to some complicated
code.  Now that we don't need the struct pid, just remove it all.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 2e0b487..8754b76 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2934,18 +2934,11 @@
 /* for the /proc/ directory itself, after non-process stuff has been done */
 int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir)
 {
-	unsigned int nr;
-	struct task_struct *reaper;
 	struct tgid_iter iter;
 	struct pid_namespace *ns;
 
 	if (filp->f_pos >= PID_MAX_LIMIT + TGID_OFFSET)
-		goto out_no_task;
-	nr = filp->f_pos - FIRST_PROCESS_ENTRY;
-
-	reaper = get_proc_task(filp->f_path.dentry->d_inode);
-	if (!reaper)
-		goto out_no_task;
+		goto out;
 
 	ns = filp->f_dentry->d_sb->s_fs_info;
 	iter.task = NULL;
@@ -2961,8 +2954,6 @@
 	}
 	filp->f_pos = PID_MAX_LIMIT + TGID_OFFSET;
 out:
-	put_task_struct(reaper);
-out_no_task:
 	return 0;
 }
 
diff --git a/fs/proc/root.c b/fs/proc/root.c
index 77b8192..cf4c922 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -42,7 +42,6 @@
 	int err;
 	struct super_block *sb;
 	struct pid_namespace *ns;
-	struct proc_inode *ei;
 
 	if (flags & MS_KERNMOUNT)
 		ns = (struct pid_namespace *)data;
@@ -64,13 +63,6 @@
 		sb->s_flags |= MS_ACTIVE;
 	}
 
-	ei = PROC_I(sb->s_root->d_inode);
-	if (!ei->pid) {
-		rcu_read_lock();
-		ei->pid = get_pid(find_pid_ns(1, ns));
-		rcu_read_unlock();
-	}
-
 	return dget(sb->s_root);
 }