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 kset_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); 178