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 struct kobject *config_kobj; 133 134 static int __init configfs_init(void) 135 { 136 int err = -ENOMEM; 137 138 configfs_dir_cachep = kmem_cache_create("configfs_dir_cache", 139 sizeof(struct configfs_dirent), 140 0, 0, NULL); 141 if (!configfs_dir_cachep) 142 goto out; 143 144 config_kobj = kobject_create_and_add("config", kernel_kobj); 145 if (!config_kobj) 146 goto out2; 147 148 err = register_filesystem(&configfs_fs_type); 149 if (err) 150 goto out3; 151 152 return 0; 153 out3: 154 pr_err("Unable to register filesystem!\n"); 155 kobject_put(config_kobj); 156 out2: 157 kmem_cache_destroy(configfs_dir_cachep); 158 configfs_dir_cachep = NULL; 159 out: 160 return err; 161 } 162 163 static void __exit configfs_exit(void) 164 { 165 unregister_filesystem(&configfs_fs_type); 166 kobject_put(config_kobj); 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