1 /* 2 * fs/sysfs/symlink.c - operations for initializing and mounting sysfs 3 * 4 * Copyright (c) 2001-3 Patrick Mochel 5 * Copyright (c) 2007 SUSE Linux Products GmbH 6 * Copyright (c) 2007 Tejun Heo <teheo@suse.de> 7 * 8 * This file is released under the GPLv2. 9 * 10 * Please see Documentation/filesystems/sysfs.txt for more information. 11 */ 12 13 #define DEBUG 14 15 #include <linux/fs.h> 16 #include <linux/mount.h> 17 #include <linux/pagemap.h> 18 #include <linux/init.h> 19 #include <linux/module.h> 20 #include <linux/magic.h> 21 #include <linux/slab.h> 22 23 #include "sysfs.h" 24 25 26 static struct vfsmount *sysfs_mnt; 27 struct kmem_cache *sysfs_dir_cachep; 28 29 static const struct super_operations sysfs_ops = { 30 .statfs = simple_statfs, 31 .drop_inode = generic_delete_inode, 32 .evict_inode = sysfs_evict_inode, 33 }; 34 35 struct sysfs_dirent sysfs_root = { 36 .s_name = "", 37 .s_count = ATOMIC_INIT(1), 38 .s_flags = SYSFS_DIR | (KOBJ_NS_TYPE_NONE << SYSFS_NS_TYPE_SHIFT), 39 .s_mode = S_IFDIR | S_IRUGO | S_IXUGO, 40 .s_ino = 1, 41 }; 42 43 static int sysfs_fill_super(struct super_block *sb, void *data, int silent) 44 { 45 struct inode *inode; 46 struct dentry *root; 47 48 sb->s_blocksize = PAGE_CACHE_SIZE; 49 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 50 sb->s_magic = SYSFS_MAGIC; 51 sb->s_op = &sysfs_ops; 52 sb->s_time_gran = 1; 53 54 /* get root inode, initialize and unlock it */ 55 mutex_lock(&sysfs_mutex); 56 inode = sysfs_get_inode(sb, &sysfs_root); 57 mutex_unlock(&sysfs_mutex); 58 if (!inode) { 59 pr_debug("sysfs: could not get root inode\n"); 60 return -ENOMEM; 61 } 62 63 /* instantiate and link root dentry */ 64 root = d_make_root(inode); 65 if (!root) { 66 pr_debug("%s: could not get root dentry!\n",__func__); 67 return -ENOMEM; 68 } 69 root->d_fsdata = &sysfs_root; 70 sb->s_root = root; 71 return 0; 72 } 73 74 static int sysfs_test_super(struct super_block *sb, void *data) 75 { 76 struct sysfs_super_info *sb_info = sysfs_info(sb); 77 struct sysfs_super_info *info = data; 78 enum kobj_ns_type type; 79 int found = 1; 80 81 for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++) { 82 if (sb_info->ns[type] != info->ns[type]) 83 found = 0; 84 } 85 return found; 86 } 87 88 static int sysfs_set_super(struct super_block *sb, void *data) 89 { 90 int error; 91 error = set_anon_super(sb, data); 92 if (!error) 93 sb->s_fs_info = data; 94 return error; 95 } 96 97 static void free_sysfs_super_info(struct sysfs_super_info *info) 98 { 99 int type; 100 for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++) 101 kobj_ns_drop(type, info->ns[type]); 102 kfree(info); 103 } 104 105 static struct dentry *sysfs_mount(struct file_system_type *fs_type, 106 int flags, const char *dev_name, void *data) 107 { 108 struct sysfs_super_info *info; 109 enum kobj_ns_type type; 110 struct super_block *sb; 111 int error; 112 113 info = kzalloc(sizeof(*info), GFP_KERNEL); 114 if (!info) 115 return ERR_PTR(-ENOMEM); 116 117 for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++) 118 info->ns[type] = kobj_ns_grab_current(type); 119 120 sb = sget(fs_type, sysfs_test_super, sysfs_set_super, info); 121 if (IS_ERR(sb) || sb->s_fs_info != info) 122 free_sysfs_super_info(info); 123 if (IS_ERR(sb)) 124 return ERR_CAST(sb); 125 if (!sb->s_root) { 126 sb->s_flags = flags; 127 error = sysfs_fill_super(sb, data, flags & MS_SILENT ? 1 : 0); 128 if (error) { 129 deactivate_locked_super(sb); 130 return ERR_PTR(error); 131 } 132 sb->s_flags |= MS_ACTIVE; 133 } 134 135 return dget(sb->s_root); 136 } 137 138 static void sysfs_kill_sb(struct super_block *sb) 139 { 140 struct sysfs_super_info *info = sysfs_info(sb); 141 /* Remove the superblock from fs_supers/s_instances 142 * so we can't find it, before freeing sysfs_super_info. 143 */ 144 kill_anon_super(sb); 145 free_sysfs_super_info(info); 146 } 147 148 static struct file_system_type sysfs_fs_type = { 149 .name = "sysfs", 150 .mount = sysfs_mount, 151 .kill_sb = sysfs_kill_sb, 152 }; 153 154 int __init sysfs_init(void) 155 { 156 int err = -ENOMEM; 157 158 sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache", 159 sizeof(struct sysfs_dirent), 160 0, 0, NULL); 161 if (!sysfs_dir_cachep) 162 goto out; 163 164 err = sysfs_inode_init(); 165 if (err) 166 goto out_err; 167 168 err = register_filesystem(&sysfs_fs_type); 169 if (!err) { 170 sysfs_mnt = kern_mount(&sysfs_fs_type); 171 if (IS_ERR(sysfs_mnt)) { 172 printk(KERN_ERR "sysfs: could not mount!\n"); 173 err = PTR_ERR(sysfs_mnt); 174 sysfs_mnt = NULL; 175 unregister_filesystem(&sysfs_fs_type); 176 goto out_err; 177 } 178 } else 179 goto out_err; 180 out: 181 return err; 182 out_err: 183 kmem_cache_destroy(sysfs_dir_cachep); 184 sysfs_dir_cachep = NULL; 185 goto out; 186 } 187 188 #undef sysfs_get 189 struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd) 190 { 191 return __sysfs_get(sd); 192 } 193 EXPORT_SYMBOL_GPL(sysfs_get); 194 195 #undef sysfs_put 196 void sysfs_put(struct sysfs_dirent *sd) 197 { 198 __sysfs_put(sd); 199 } 200 EXPORT_SYMBOL_GPL(sysfs_put); 201