/* -*- mode: c; c-basic-offset: 8; -*-
   * vim: noexpandtab sw=8 ts=8 sts=0:
   *
   * mount.c - operations for initializing and mounting configfs.
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public
   * License as published by the Free Software Foundation; either
   * version 2 of the License, or (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * General Public License for more details.
   *
   * You should have received a copy of the GNU General Public
   * License along with this program; if not, write to the
   * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   * Boston, MA 021110-1307, USA.
   *
   * Based on sysfs:
   * 	sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
   *
   * configfs Copyright (C) 2005 Oracle.  All rights reserved.
   */
  
  #include <linux/fs.h>
  #include <linux/module.h>
  #include <linux/mount.h>
  #include <linux/pagemap.h>
  #include <linux/init.h>

  #include <linux/slab.h>

  
  #include <linux/configfs.h>
  #include "configfs_internal.h"
  
  /* Random magic number */
  #define CONFIGFS_MAGIC 0x62656570

  static struct vfsmount *configfs_mount = NULL;

  struct kmem_cache *configfs_dir_cachep;

  static int configfs_mnt_count = 0;

  static const struct super_operations configfs_ops = {

  	.statfs		= simple_statfs,
  	.drop_inode	= generic_delete_inode,
  };
  
  static struct config_group configfs_root_group = {
  	.cg_item = {
  		.ci_namebuf	= "root",
  		.ci_name	= configfs_root_group.cg_item.ci_namebuf,
  	},
  };
  
  int configfs_is_root(struct config_item *item)
  {
  	return item == &configfs_root_group.cg_item;
  }
  
  static struct configfs_dirent configfs_root = {
  	.s_sibling	= LIST_HEAD_INIT(configfs_root.s_sibling),
  	.s_children	= LIST_HEAD_INIT(configfs_root.s_children),
  	.s_element	= &configfs_root_group.cg_item,
  	.s_type		= CONFIGFS_ROOT,

  	.s_iattr	= NULL,

  };
  
  static int configfs_fill_super(struct super_block *sb, void *data, int silent)
  {
  	struct inode *inode;
  	struct dentry *root;

  	sb->s_blocksize = PAGE_SIZE;
  	sb->s_blocksize_bits = PAGE_SHIFT;

  	sb->s_magic = CONFIGFS_MAGIC;
  	sb->s_op = &configfs_ops;

  	sb->s_time_gran = 1;

  	inode = configfs_new_inode(S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,

  				   &configfs_root, sb);

  	if (inode) {

  		inode->i_op = &configfs_root_inode_operations;

  		inode->i_fop = &configfs_dir_operations;
  		/* directory inodes start off with i_nlink == 2 (for "." entry) */

  		inc_nlink(inode);

  	} else {

  		pr_debug("could not get root inode
  ");

  		return -ENOMEM;
  	}

  	root = d_make_root(inode);

  	if (!root) {

  		pr_debug("%s: could not get root dentry!
  ",__func__);

  		return -ENOMEM;
  	}
  	config_group_init(&configfs_root_group);
  	configfs_root_group.cg_item.ci_dentry = root;
  	root->d_fsdata = &configfs_root;
  	sb->s_root = root;

  	sb->s_d_op = &configfs_dentry_ops; /* the rest get that */

  	return 0;
  }

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

  {

  	return mount_single(fs_type, flags, data, configfs_fill_super);

  }
  
  static struct file_system_type configfs_fs_type = {
  	.owner		= THIS_MODULE,
  	.name		= "configfs",

  	.mount		= configfs_do_mount,

  	.kill_sb	= kill_litter_super,
  };

  MODULE_ALIAS_FS("configfs");

  struct dentry *configfs_pin_fs(void)

  {

  	int err = simple_pin_fs(&configfs_fs_type, &configfs_mount,

  			     &configfs_mnt_count);

  	return err ? ERR_PTR(err) : configfs_mount->mnt_root;

  }
  
  void configfs_release_fs(void)
  {
  	simple_release_fs(&configfs_mount, &configfs_mnt_count);
  }

  static int __init configfs_init(void)
  {

  	int err = -ENOMEM;
  
  	configfs_dir_cachep = kmem_cache_create("configfs_dir_cache",
  						sizeof(struct configfs_dirent),

  						0, 0, NULL);

  	if (!configfs_dir_cachep)
  		goto out;

  	err = sysfs_create_mount_point(kernel_kobj, "config");
  	if (err)

  		goto out2;

  	err = register_filesystem(&configfs_fs_type);

  	if (err)

  		goto out3;

  	return 0;

  out3:

  	pr_err("Unable to register filesystem!
  ");

  	sysfs_remove_mount_point(kernel_kobj, "config");

  out2:
  	kmem_cache_destroy(configfs_dir_cachep);
  	configfs_dir_cachep = NULL;

  out:

  	return err;
  }
  
  static void __exit configfs_exit(void)
  {
  	unregister_filesystem(&configfs_fs_type);

  	sysfs_remove_mount_point(kernel_kobj, "config");

  	kmem_cache_destroy(configfs_dir_cachep);
  	configfs_dir_cachep = NULL;

  }
  
  MODULE_AUTHOR("Oracle");
  MODULE_LICENSE("GPL");

  MODULE_VERSION("0.0.2");

  MODULE_DESCRIPTION("Simple RAM filesystem for user driven kernel subsystem configuration.");

  core_initcall(configfs_init);

  module_exit(configfs_exit);