fs/configfs/mount.c

   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
  40 struct vfsmount * configfs_mount = NULL;
  41 struct super_block * configfs_sb = NULL;
  42 struct kmem_cache *configfs_dir_cachep;
  43 static int configfs_mnt_count = 0;
  44
  45 static const struct super_operations configfs_ops = {
  46         .statfs         = simple_statfs,
  47         .drop_inode     = generic_delete_inode,
  48 };
  49
  50 static struct config_group configfs_root_group = {
  51         .cg_item = {
  52                 .ci_namebuf     = "root",
  53                 .ci_name        = configfs_root_group.cg_item.ci_namebuf,
  54         },
  55 };
  56
  57 int configfs_is_root(struct config_item *item)
  58 {
  59         return item == &configfs_root_group.cg_item;
  60 }
  61
  62 static struct configfs_dirent configfs_root = {
  63         .s_sibling      = LIST_HEAD_INIT(configfs_root.s_sibling),
  64         .s_children     = LIST_HEAD_INIT(configfs_root.s_children),
  65         .s_element      = &configfs_root_group.cg_item,
  66         .s_type         = CONFIGFS_ROOT,
  67         .s_iattr        = NULL,
  68 };
  69
  70 static int configfs_fill_super(struct super_block *sb, void *data, int silent)
  71 {
  72         struct inode *inode;
  73         struct dentry *root;
  74
  75         sb->s_blocksize = PAGE_CACHE_SIZE;
  76         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
  77         sb->s_magic = CONFIGFS_MAGIC;
  78         sb->s_op = &configfs_ops;
  79         sb->s_time_gran = 1;
  80         configfs_sb = sb;
  81
  82         inode = configfs_new_inode(S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
  83                                    &configfs_root);
  84         if (inode) {
  85                 inode->i_op = &configfs_dir_inode_operations;
  86                 inode->i_fop = &configfs_dir_operations;
  87                 /* directory inodes start off with i_nlink == 2 (for "." entry) */
  88                 inc_nlink(inode);
  89         } else {
  90                 pr_debug("configfs: could not get root inode\n");
  91                 return -ENOMEM;
  92         }
  93
  94         root = d_alloc_root(inode);
  95         if (!root) {
  96                 pr_debug("%s: could not get root dentry!\n",__func__);
  97                 iput(inode);
  98                 return -ENOMEM;
  99         }
 100         config_group_init(&configfs_root_group);
 101         configfs_root_group.cg_item.ci_dentry = root;
 102         root->d_fsdata = &configfs_root;
 103         sb->s_root = root;
 104         sb->s_d_op = &configfs_dentry_ops; /* the rest get that */
 105         return 0;
 106 }
 107
 108 static struct dentry *configfs_do_mount(struct file_system_type *fs_type,
 109         int flags, const char *dev_name, void *data)
 110 {
 111         return mount_single(fs_type, flags, data, configfs_fill_super);
 112 }
 113
 114 static struct file_system_type configfs_fs_type = {
 115         .owner          = THIS_MODULE,
 116         .name           = "configfs",
 117         .mount          = configfs_do_mount,
 118         .kill_sb        = kill_litter_super,
 119 };
 120
 121 int configfs_pin_fs(void)
 122 {
 123         return simple_pin_fs(&configfs_fs_type, &configfs_mount,
 124                              &configfs_mnt_count);
 125 }
 126
 127 void configfs_release_fs(void)
 128 {
 129         simple_release_fs(&configfs_mount, &configfs_mnt_count);
 130 }
 131
 132
 133 static struct kobject *config_kobj;
 134
 135 static int __init configfs_init(void)
 136 {
 137         int err = -ENOMEM;
 138
 139         configfs_dir_cachep = kmem_cache_create("configfs_dir_cache",
 140                                                 sizeof(struct configfs_dirent),
 141                                                 0, 0, NULL);
 142         if (!configfs_dir_cachep)
 143                 goto out;
 144
 145         config_kobj = kobject_create_and_add("config", kernel_kobj);
 146         if (!config_kobj) {
 147                 kmem_cache_destroy(configfs_dir_cachep);
 148                 configfs_dir_cachep = NULL;
 149                 goto out;
 150         }
 151
 152         err = register_filesystem(&configfs_fs_type);
 153         if (err) {
 154                 printk(KERN_ERR "configfs: Unable to register filesystem!\n");
 155                 kobject_put(config_kobj);
 156                 kmem_cache_destroy(configfs_dir_cachep);
 157                 configfs_dir_cachep = NULL;
 158                 goto out;
 159         }
 160
 161         err = configfs_inode_init();
 162         if (err) {
 163                 unregister_filesystem(&configfs_fs_type);
 164                 kobject_put(config_kobj);
 165                 kmem_cache_destroy(configfs_dir_cachep);
 166                 configfs_dir_cachep = NULL;
 167         }
 168 out:
 169         return err;
 170 }
 171
 172 static void __exit configfs_exit(void)
 173 {
 174         unregister_filesystem(&configfs_fs_type);
 175         kobject_put(config_kobj);
 176         kmem_cache_destroy(configfs_dir_cachep);
 177         configfs_dir_cachep = NULL;
 178         configfs_inode_exit();
 179 }
 180
 181 MODULE_AUTHOR("Oracle");
 182 MODULE_LICENSE("GPL");
 183 MODULE_VERSION("0.0.2");
 184 MODULE_DESCRIPTION("Simple RAM filesystem for user driven kernel subsystem configuration.");
 185
 186 module_init(configfs_init);
 187 module_exit(configfs_exit);