/*
 *  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);
}