/*
   *  linux/fs/proc/root.c
   *
   *  Copyright (C) 1991, 1992 Linus Torvalds
   *
   *  proc root directory handling functions
   */
  
  #include <asm/uaccess.h>
  
  #include <linux/errno.h>
  #include <linux/time.h>
  #include <linux/proc_fs.h>
  #include <linux/stat.h>

  #include <linux/init.h>

  #include <linux/sched.h>

  #include <linux/module.h>
  #include <linux/bitops.h>

  #include <linux/mount.h>

  #include <linux/pid_namespace.h>

  #include "internal.h"

  static int proc_test_super(struct super_block *sb, void *data)
  {
  	return sb->s_fs_info == data;
  }
  
  static int proc_set_super(struct super_block *sb, void *data)
  {

  	int err = set_anon_super(sb, NULL);
  	if (!err) {
  		struct pid_namespace *ns = (struct pid_namespace *)data;
  		sb->s_fs_info = get_pid_ns(ns);
  	}
  	return err;

  }

  static struct dentry *proc_mount(struct file_system_type *fs_type,
  	int flags, const char *dev_name, void *data)

  {

  	int err;
  	struct super_block *sb;
  	struct pid_namespace *ns;
  	struct proc_inode *ei;

  	if (flags & MS_KERNMOUNT)
  		ns = (struct pid_namespace *)data;
  	else
  		ns = current->nsproxy->pid_ns;
  
  	sb = sget(fs_type, proc_test_super, proc_set_super, ns);
  	if (IS_ERR(sb))

  		return ERR_CAST(sb);

  
  	if (!sb->s_root) {
  		sb->s_flags = flags;
  		err = proc_fill_super(sb);
  		if (err) {

  			deactivate_locked_super(sb);

  			return ERR_PTR(err);

  		}

  		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);

  }
  
  static void proc_kill_sb(struct super_block *sb)
  {
  	struct pid_namespace *ns;
  
  	ns = (struct pid_namespace *)sb->s_fs_info;
  	kill_anon_super(sb);
  	put_pid_ns(ns);

  }

  static struct file_system_type proc_fs_type = {

  	.name		= "proc",

  	.mount		= proc_mount,

  	.kill_sb	= proc_kill_sb,

  };

  void __init proc_root_init(void)
  {

  	int err;
  
  	proc_init_inodecache();

  	err = register_filesystem(&proc_fs_type);
  	if (err)
  		return;

  	err = pid_ns_prepare_proc(&init_pid_ns);
  	if (err) {

  		unregister_filesystem(&proc_fs_type);
  		return;
  	}

  	proc_symlink("mounts", NULL, "self/mounts");

  
  	proc_net_init();

  
  #ifdef CONFIG_SYSVIPC
  	proc_mkdir("sysvipc", NULL);
  #endif

  	proc_mkdir("fs", NULL);

  	proc_mkdir("driver", NULL);

  	proc_mkdir("fs/nfsd", NULL); /* somewhere for the nfsd filesystem to be mounted */
  #if defined(CONFIG_SUN_OPENPROMFS) || defined(CONFIG_SUN_OPENPROMFS_MODULE)
  	/* just give it a mountpoint */
  	proc_mkdir("openprom", NULL);
  #endif
  	proc_tty_init();
  #ifdef CONFIG_PROC_DEVICETREE
  	proc_device_tree_init();
  #endif

  	proc_mkdir("bus", NULL);

  	proc_sys_init();

  }

  static int proc_root_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat
  )

  {

  	generic_fillattr(dentry->d_inode, stat);
  	stat->nlink = proc_root.nlink + nr_processes();
  	return 0;
  }

  static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentry, struct nameidata *nd)
  {

  	if (!proc_lookup(dir, dentry, nd)) {
  		return NULL;
  	}
  	
  	return proc_pid_lookup(dir, dentry, nd);
  }
  
  static int proc_root_readdir(struct file * filp,
  	void * dirent, filldir_t filldir)
  {
  	unsigned int nr = filp->f_pos;
  	int ret;

  	if (nr < FIRST_PROCESS_ENTRY) {
  		int error = proc_readdir(filp, dirent, filldir);

  		if (error <= 0)

  			return error;

  		filp->f_pos = FIRST_PROCESS_ENTRY;
  	}

  
  	ret = proc_pid_readdir(filp, dirent, filldir);
  	return ret;
  }
  
  /*
   * The root /proc directory is special, as it has the
   * <pid> directories. Thus we don't use the generic
   * directory handling functions for that..
   */

  static const struct file_operations proc_root_operations = {

  	.read		 = generic_read_dir,
  	.readdir	 = proc_root_readdir,

  	.llseek		= default_llseek,

  };
  
  /*
   * proc root can do almost nothing..
   */

  static const struct inode_operations proc_root_inode_operations = {

  	.lookup		= proc_root_lookup,

  	.getattr	= proc_root_getattr,

  };
  
  /*
   * This is the root "inode" in the /proc tree..
   */
  struct proc_dir_entry proc_root = {
  	.low_ino	= PROC_ROOT_INO, 
  	.namelen	= 5, 

  	.mode		= S_IFDIR | S_IRUGO | S_IXUGO, 
  	.nlink		= 2, 

  	.count		= ATOMIC_INIT(1),

  	.proc_iops	= &proc_root_inode_operations, 
  	.proc_fops	= &proc_root_operations,
  	.parent		= &proc_root,

  	.name		= "/proc",

  };

  int pid_ns_prepare_proc(struct pid_namespace *ns)
  {
  	struct vfsmount *mnt;
  
  	mnt = kern_mount_data(&proc_fs_type, ns);
  	if (IS_ERR(mnt))
  		return PTR_ERR(mnt);

  	ns->proc_mnt = mnt;

  	return 0;
  }
  
  void pid_ns_release_proc(struct pid_namespace *ns)
  {

  	kern_unmount(ns->proc_mnt);

  }