linux/fs/configfs/mount.c
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   1/* -*- mode: c; c-basic-offset: 8; -*-
   2 * vim: noexpandtab sw=8 ts=8 sts=0:
   3 *
   4 * mount.c - operations for initializing and mounting configfs.
   5 *
   6 * This program is free software; you can redistribute it and/or
   7 * modify it under the terms of the GNU General Public
   8 * License as published by the Free Software Foundation; either
   9 * version 2 of the License, or (at your option) any later version.
  10 *
  11 * This program is distributed in the hope that it will be useful,
  12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 * General Public License for more details.
  15 *
  16 * You should have received a copy of the GNU General Public
  17 * License along with this program; if not, write to the
  18 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19 * Boston, MA 021110-1307, USA.
  20 *
  21 * Based on sysfs:
  22 *      sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
  23 *
  24 * configfs Copyright (C) 2005 Oracle.  All rights reserved.
  25 */
  26
  27#include <linux/fs.h>
  28#include <linux/module.h>
  29#include <linux/mount.h>
  30#include <linux/pagemap.h>
  31#include <linux/init.h>
  32#include <linux/slab.h>
  33
  34#include <linux/configfs.h>
  35#include "configfs_internal.h"
  36
  37/* Random magic number */
  38#define CONFIGFS_MAGIC 0x62656570
  39
  40static struct vfsmount *configfs_mount = NULL;
  41struct kmem_cache *configfs_dir_cachep;
  42static int configfs_mnt_count = 0;
  43
  44static const struct super_operations configfs_ops = {
  45        .statfs         = simple_statfs,
  46        .drop_inode     = generic_delete_inode,
  47};
  48
  49static struct config_group configfs_root_group = {
  50        .cg_item = {
  51                .ci_namebuf     = "root",
  52                .ci_name        = configfs_root_group.cg_item.ci_namebuf,
  53        },
  54};
  55
  56int configfs_is_root(struct config_item *item)
  57{
  58        return item == &configfs_root_group.cg_item;
  59}
  60
  61static struct configfs_dirent configfs_root = {
  62        .s_sibling      = LIST_HEAD_INIT(configfs_root.s_sibling),
  63        .s_children     = LIST_HEAD_INIT(configfs_root.s_children),
  64        .s_element      = &configfs_root_group.cg_item,
  65        .s_type         = CONFIGFS_ROOT,
  66        .s_iattr        = NULL,
  67};
  68
  69static int configfs_fill_super(struct super_block *sb, void *data, int silent)
  70{
  71        struct inode *inode;
  72        struct dentry *root;
  73
  74        sb->s_blocksize = PAGE_CACHE_SIZE;
  75        sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
  76        sb->s_magic = CONFIGFS_MAGIC;
  77        sb->s_op = &configfs_ops;
  78        sb->s_time_gran = 1;
  79
  80        inode = configfs_new_inode(S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
  81                                   &configfs_root, sb);
  82        if (inode) {
  83                inode->i_op = &configfs_root_inode_operations;
  84                inode->i_fop = &configfs_dir_operations;
  85                /* directory inodes start off with i_nlink == 2 (for "." entry) */
  86                inc_nlink(inode);
  87        } else {
  88                pr_debug("configfs: could not get root inode\n");
  89                return -ENOMEM;
  90        }
  91
  92        root = d_make_root(inode);
  93        if (!root) {
  94                pr_debug("%s: could not get root dentry!\n",__func__);
  95                return -ENOMEM;
  96        }
  97        config_group_init(&configfs_root_group);
  98        configfs_root_group.cg_item.ci_dentry = root;
  99        root->d_fsdata = &configfs_root;
 100        sb->s_root = root;
 101        sb->s_d_op = &configfs_dentry_ops; /* the rest get that */
 102        return 0;
 103}
 104
 105static struct dentry *configfs_do_mount(struct file_system_type *fs_type,
 106        int flags, const char *dev_name, void *data)
 107{
 108        return mount_single(fs_type, flags, data, configfs_fill_super);
 109}
 110
 111static struct file_system_type configfs_fs_type = {
 112        .owner          = THIS_MODULE,
 113        .name           = "configfs",
 114        .mount          = configfs_do_mount,
 115        .kill_sb        = kill_litter_super,
 116};
 117MODULE_ALIAS_FS("configfs");
 118
 119struct dentry *configfs_pin_fs(void)
 120{
 121        int err = simple_pin_fs(&configfs_fs_type, &configfs_mount,
 122                             &configfs_mnt_count);
 123        return err ? ERR_PTR(err) : configfs_mount->mnt_root;
 124}
 125
 126void configfs_release_fs(void)
 127{
 128        simple_release_fs(&configfs_mount, &configfs_mnt_count);
 129}
 130
 131
 132static struct kobject *config_kobj;
 133
 134static int __init configfs_init(void)
 135{
 136        int err = -ENOMEM;
 137
 138        configfs_dir_cachep = kmem_cache_create("configfs_dir_cache",
 139                                                sizeof(struct configfs_dirent),
 140                                                0, 0, NULL);
 141        if (!configfs_dir_cachep)
 142                goto out;
 143
 144        config_kobj = kobject_create_and_add("config", kernel_kobj);
 145        if (!config_kobj)
 146                goto out2;
 147
 148        err = configfs_inode_init();
 149        if (err)
 150                goto out3;
 151
 152        err = register_filesystem(&configfs_fs_type);
 153        if (err)
 154                goto out4;
 155
 156        return 0;
 157out4:
 158        printk(KERN_ERR "configfs: Unable to register filesystem!\n");
 159        configfs_inode_exit();
 160out3:
 161        kobject_put(config_kobj);
 162out2:
 163        kmem_cache_destroy(configfs_dir_cachep);
 164        configfs_dir_cachep = NULL;
 165out:
 166        return err;
 167}
 168
 169static void __exit configfs_exit(void)
 170{
 171        unregister_filesystem(&configfs_fs_type);
 172        kobject_put(config_kobj);
 173        kmem_cache_destroy(configfs_dir_cachep);
 174        configfs_dir_cachep = NULL;
 175        configfs_inode_exit();
 176}
 177
 178MODULE_AUTHOR("Oracle");
 179MODULE_LICENSE("GPL");
 180MODULE_VERSION("0.0.2");
 181MODULE_DESCRIPTION("Simple RAM filesystem for user driven kernel subsystem configuration.");
 182
 183module_init(configfs_init);
 184module_exit(configfs_exit);
 185
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