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 static struct vfsmount *configfs_mount = 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
  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("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
 105 static 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
 111 static 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 };
 117 MODULE_ALIAS_FS("configfs");
 118
 119 struct 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
 126 void configfs_release_fs(void)
 127 {
 128         simple_release_fs(&configfs_mount, &configfs_mnt_count);
 129 }
 130
 131
 132 static int __init configfs_init(void)
 133 {
 134         int err = -ENOMEM;
 135
 136         configfs_dir_cachep = kmem_cache_create("configfs_dir_cache",
 137                                                 sizeof(struct configfs_dirent),
 138                                                 0, 0, NULL);
 139         if (!configfs_dir_cachep)
 140                 goto out;
 141
 142         err = sysfs_create_mount_point(kernel_kobj, "config");
 143         if (err)
 144                 goto out2;
 145
 146         err = register_filesystem(&configfs_fs_type);
 147         if (err)
 148                 goto out3;
 149
 150         return 0;
 151 out3:
 152         pr_err("Unable to register filesystem!\n");
 153         sysfs_remove_mount_point(kernel_kobj, "config");
 154 out2:
 155         kmem_cache_destroy(configfs_dir_cachep);
 156         configfs_dir_cachep = NULL;
 157 out:
 158         return err;
 159 }
 160
 161 static void __exit configfs_exit(void)
 162 {
 163         unregister_filesystem(&configfs_fs_type);
 164         sysfs_remove_mount_point(kernel_kobj, "config");
 165         kmem_cache_destroy(configfs_dir_cachep);
 166         configfs_dir_cachep = NULL;
 167 }
 168
 169 MODULE_AUTHOR("Oracle");
 170 MODULE_LICENSE("GPL");
 171 MODULE_VERSION("0.0.2");
 172 MODULE_DESCRIPTION("Simple RAM filesystem for user driven kernel subsystem configuration.");
 173
 174 core_initcall(configfs_init);
 175 module_exit(configfs_exit);