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 static int configfs_mnt_count = 0;
  42
  43 static struct super_operations configfs_ops = {
  44         .statfs         = simple_statfs,
  45         .drop_inode     = generic_delete_inode,
  46 };
  47
  48 static struct config_group configfs_root_group = {
  49         .cg_item = {
  50                 .ci_namebuf     = "root",
  51                 .ci_name        = configfs_root_group.cg_item.ci_namebuf,
  52         },
  53 };
  54
  55 int configfs_is_root(struct config_item *item)
  56 {
  57         return item == &configfs_root_group.cg_item;
  58 }
  59
  60 static struct configfs_dirent configfs_root = {
  61         .s_sibling      = LIST_HEAD_INIT(configfs_root.s_sibling),
  62         .s_children     = LIST_HEAD_INIT(configfs_root.s_children),
  63         .s_element      = &configfs_root_group.cg_item,
  64         .s_type         = CONFIGFS_ROOT,
  65 };
  66
  67 static int configfs_fill_super(struct super_block *sb, void *data, int silent)
  68 {
  69         struct inode *inode;
  70         struct dentry *root;
  71
  72         sb->s_blocksize = PAGE_CACHE_SIZE;
  73         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
  74         sb->s_magic = CONFIGFS_MAGIC;
  75         sb->s_op = &configfs_ops;
  76         configfs_sb = sb;
  77
  78         inode = configfs_new_inode(S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO);
  79         if (inode) {
  80                 inode->i_op = &configfs_dir_inode_operations;
  81                 inode->i_fop = &configfs_dir_operations;
  82                 /* directory inodes start off with i_nlink == 2 (for "." entry) */
  83                 inode->i_nlink++;
  84         } else {
  85                 pr_debug("configfs: could not get root inode\n");
  86                 return -ENOMEM;
  87         }
  88
  89         root = d_alloc_root(inode);
  90         if (!root) {
  91                 pr_debug("%s: could not get root dentry!\n",__FUNCTION__);
  92                 iput(inode);
  93                 return -ENOMEM;
  94         }
  95         config_group_init(&configfs_root_group);
  96         configfs_root_group.cg_item.ci_dentry = root;
  97         root->d_fsdata = &configfs_root;
  98         sb->s_root = root;
  99         return 0;
 100 }
 101
 102 static struct super_block *configfs_get_sb(struct file_system_type *fs_type,
 103         int flags, const char *dev_name, void *data)
 104 {
 105         return get_sb_single(fs_type, flags, data, configfs_fill_super);
 106 }
 107
 108 static struct file_system_type configfs_fs_type = {
 109         .owner          = THIS_MODULE,
 110         .name           = "configfs",
 111         .get_sb         = configfs_get_sb,
 112         .kill_sb        = kill_litter_super,
 113 };
 114
 115 int configfs_pin_fs(void)
 116 {
 117         return simple_pin_fs("configfs", &configfs_mount,
 118                              &configfs_mnt_count);
 119 }
 120
 121 void configfs_release_fs(void)
 122 {
 123         simple_release_fs(&configfs_mount, &configfs_mnt_count);
 124 }
 125
 126
 127 static decl_subsys(config, NULL, NULL);
 128
 129 static int __init configfs_init(void)
 130 {
 131         int err;
 132
 133         kset_set_kset_s(&config_subsys, kernel_subsys);
 134         err = subsystem_register(&config_subsys);
 135         if (err)
 136                 return err;
 137
 138         err = register_filesystem(&configfs_fs_type);
 139         if (err) {
 140                 printk(KERN_ERR "configfs: Unable to register filesystem!\n");
 141                 subsystem_unregister(&config_subsys);
 142         }
 143
 144         return err;
 145 }
 146
 147 static void __exit configfs_exit(void)
 148 {
 149         unregister_filesystem(&configfs_fs_type);
 150         subsystem_unregister(&config_subsys);
 151 }
 152
 153 MODULE_AUTHOR("Oracle");
 154 MODULE_LICENSE("GPL");
 155 MODULE_VERSION("0.0.1");
 156 MODULE_DESCRIPTION("Simple RAM filesystem for user driven kernel subsystem configuration.");
 157
 158 module_init(configfs_init);
 159 module_exit(configfs_exit);