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
  33 #include <linux/configfs.h>
  34 #include "configfs_internal.h"
  35
  36 /* Random magic number */
  37 #define CONFIGFS_MAGIC 0x62656570
  38
  39 struct vfsmount * configfs_mount = NULL;
  40 struct super_block * configfs_sb = NULL;
  41 struct kmem_cache *configfs_dir_cachep;
  42 static int configfs_mnt_count = 0;
  43
  44 static const struct super_operations configfs_ops = {
  45         .statfs         = simple_statfs,
  46         .drop_inode     = generic_delete_inode,
  47 };
  48
  49 static 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
  56 int configfs_is_root(struct config_item *item)
  57 {
  58         return item == &configfs_root_group.cg_item;
  59 }
  60
  61 static 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
  69 static 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         configfs_sb = sb;
  80
  81         inode = configfs_new_inode(S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
  82                                    &configfs_root);
  83         if (inode) {
  84                 inode->i_op = &configfs_dir_inode_operations;
  85                 inode->i_fop = &configfs_dir_operations;
  86                 /* directory inodes start off with i_nlink == 2 (for "." entry) */
  87                 inc_nlink(inode);
  88         } else {
  89                 pr_debug("configfs: could not get root inode\n");
  90                 return -ENOMEM;
  91         }
  92
  93         root = d_alloc_root(inode);
  94         if (!root) {
  95                 pr_debug("%s: could not get root dentry!\n",__FUNCTION__);
  96                 iput(inode);
  97                 return -ENOMEM;
  98         }
  99         config_group_init(&configfs_root_group);
 100         configfs_root_group.cg_item.ci_dentry = root;
 101         root->d_fsdata = &configfs_root;
 102         sb->s_root = root;
 103         return 0;
 104 }
 105
 106 static int configfs_get_sb(struct file_system_type *fs_type,
 107         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
 108 {
 109         return get_sb_single(fs_type, flags, data, configfs_fill_super, mnt);
 110 }
 111
 112 static struct file_system_type configfs_fs_type = {
 113         .owner          = THIS_MODULE,
 114         .name           = "configfs",
 115         .get_sb         = configfs_get_sb,
 116         .kill_sb        = kill_litter_super,
 117 };
 118
 119 int configfs_pin_fs(void)
 120 {
 121         return simple_pin_fs(&configfs_fs_type, &configfs_mount,
 122                              &configfs_mnt_count);
 123 }
 124
 125 void configfs_release_fs(void)
 126 {
 127         simple_release_fs(&configfs_mount, &configfs_mnt_count);
 128 }
 129
 130
 131 static decl_subsys(config, NULL, NULL);
 132
 133 static int __init configfs_init(void)
 134 {
 135         int err = -ENOMEM;
 136
 137         configfs_dir_cachep = kmem_cache_create("configfs_dir_cache",
 138                                                 sizeof(struct configfs_dirent),
 139                                                 0, 0, NULL, NULL);
 140         if (!configfs_dir_cachep)
 141                 goto out;
 142
 143         kobj_set_kset_s(&config_subsys, kernel_subsys);
 144         err = subsystem_register(&config_subsys);
 145         if (err) {
 146                 kmem_cache_destroy(configfs_dir_cachep);
 147                 configfs_dir_cachep = NULL;
 148                 goto out;
 149         }
 150
 151         err = register_filesystem(&configfs_fs_type);
 152         if (err) {
 153                 printk(KERN_ERR "configfs: Unable to register filesystem!\n");
 154                 subsystem_unregister(&config_subsys);
 155                 kmem_cache_destroy(configfs_dir_cachep);
 156                 configfs_dir_cachep = NULL;
 157         }
 158
 159 out:
 160         return err;
 161 }
 162
 163 static void __exit configfs_exit(void)
 164 {
 165         unregister_filesystem(&configfs_fs_type);
 166         subsystem_unregister(&config_subsys);
 167         kmem_cache_destroy(configfs_dir_cachep);
 168         configfs_dir_cachep = NULL;
 169 }
 170
 171 MODULE_AUTHOR("Oracle");
 172 MODULE_LICENSE("GPL");
 173 MODULE_VERSION("0.0.2");
 174 MODULE_DESCRIPTION("Simple RAM filesystem for user driven kernel subsystem configuration.");
 175
 176 module_init(configfs_init);
 177 module_exit(configfs_exit);