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  /*
   *  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/smp_lock.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)
 {
         struct pid_namespace *ns;
 
         ns = (struct pid_namespace *)data;
         sb->s_fs_info = get_pid_ns(ns);
         return set_anon_super(sb, NULL);
 }
 
 static int proc_get_sb(struct file_system_type *fs_type,
         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
 {
         int err;
         struct super_block *sb;
         struct pid_namespace *ns;
         struct proc_inode *ei;
 
         if (proc_mnt) {
                 /* Seed the root directory with a pid so it doesn't need
                  * to be special in base.c.  I would do this earlier but
                  * the only task alive when /proc is mounted the first time
                  * is the init_task and it doesn't have any pids.
                  */
                 ei = PROC_I(proc_mnt->mnt_sb->s_root->d_inode);
                 if (!ei->pid)
                         ei->pid = find_get_pid(1);
         }
 
         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 PTR_ERR(sb);
 
         if (!sb->s_root) {
                 sb->s_flags = flags;
                 err = proc_fill_super(sb);
                 if (err) {
                         up_write(&sb->s_umount);
                         deactivate_super(sb);
                         return err;
                 }
 
                 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();
                 }
 
                 sb->s_flags |= MS_ACTIVE;
                 ns->proc_mnt = mnt;
         }
 
         return simple_set_mnt(mnt, sb);
 }
 
 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",
        .get_sb                = proc_get_sb,
        .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;
        proc_mnt = kern_mount_data(&proc_fs_type, &init_pid_ns);
        err = PTR_ERR(proc_mnt);
        if (IS_ERR(proc_mnt)) {
                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;

        lock_kernel();

        if (nr < FIRST_PROCESS_ENTRY) {
                int error = proc_readdir(filp, dirent, filldir);
                if (error <= 0) {
                        unlock_kernel();
                        return error;
                }
                filp->f_pos = FIRST_PROCESS_ENTRY;
        }
        unlock_kernel();

        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,
};

/*
 * 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, 
        .name                = "/proc",
        .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,
};

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);

        return 0;
}

void pid_ns_release_proc(struct pid_namespace *ns)
{
        mntput(ns->proc_mnt);
}

EXPORT_SYMBOL(proc_symlink);
EXPORT_SYMBOL(proc_mkdir);
EXPORT_SYMBOL(create_proc_entry);
EXPORT_SYMBOL(proc_create_data);
EXPORT_SYMBOL(remove_proc_entry);