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_IRWXU | 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_alloc_root(inode); 65 if (!root) { 66 pr_debug("%s: could not get root dentry!\n",__func__); 67 iput(inode); 68 return -ENOMEM; 69 } 70 root->d_fsdata = &sysfs_root; 71 sb->s_root = root; 72 return 0; 73 } 74 75 static int sysfs_test_super(struct super_block *sb, void *data) 76 { 77 struct sysfs_super_info *sb_info = sysfs_info(sb); 78 struct sysfs_super_info *info = data; 79 enum kobj_ns_type type; 80 int found = 1; 81 82 for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++) { 83 if (sb_info->ns[type] != info->ns[type]) 84 found = 0; 85 } 86 return found; 87 } 88 89 static int sysfs_set_super(struct super_block *sb, void *data) 90 { 91 int error; 92 error = set_anon_super(sb, data); 93 if (!error) 94 sb->s_fs_info = data; 95 return error; 96 } 97 98 static struct dentry *sysfs_mount(struct file_system_type *fs_type, 99 int flags, const char *dev_name, void *data) 100 { 101 struct sysfs_super_info *info; 102 enum kobj_ns_type type; 103 struct super_block *sb; 104 int error; 105 106 info = kzalloc(sizeof(*info), GFP_KERNEL); 107 if (!info) 108 return ERR_PTR(-ENOMEM); 109 110 for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++) 111 info->ns[type] = kobj_ns_current(type); 112 113 sb = sget(fs_type, sysfs_test_super, sysfs_set_super, info); 114 if (IS_ERR(sb) || sb->s_fs_info != info) 115 kfree(info); 116 if (IS_ERR(sb)) 117 return ERR_CAST(sb); 118 if (!sb->s_root) { 119 sb->s_flags = flags; 120 error = sysfs_fill_super(sb, data, flags & MS_SILENT ? 1 : 0); 121 if (error) { 122 deactivate_locked_super(sb); 123 return ERR_PTR(error); 124 } 125 sb->s_flags |= MS_ACTIVE; 126 } 127 128 return dget(sb->s_root); 129 } 130 131 static void sysfs_kill_sb(struct super_block *sb) 132 { 133 struct sysfs_super_info *info = sysfs_info(sb); 134 135 /* Remove the superblock from fs_supers/s_instances 136 * so we can't find it, before freeing sysfs_super_info. 137 */ 138 kill_anon_super(sb); 139 kfree(info); 140 } 141 142 static struct file_system_type sysfs_fs_type = { 143 .name = "sysfs", 144 .mount = sysfs_mount, 145 .kill_sb = sysfs_kill_sb, 146 }; 147 148 void sysfs_exit_ns(enum kobj_ns_type type, const void *ns) 149 { 150 struct super_block *sb; 151 152 mutex_lock(&sysfs_mutex); 153 spin_lock(&sb_lock); 154 list_for_each_entry(sb, &sysfs_fs_type.fs_supers, s_instances) { 155 struct sysfs_super_info *info = sysfs_info(sb); 156 /* 157 * If we see a superblock on the fs_supers/s_instances 158 * list the unmount has not completed and sb->s_fs_info 159 * points to a valid struct sysfs_super_info. 160 */ 161 /* Ignore superblocks with the wrong ns */ 162 if (info->ns[type] != ns) 163 continue; 164 info->ns[type] = NULL; 165 } 166 spin_unlock(&sb_lock); 167 mutex_unlock(&sysfs_mutex); 168 } 169 170 int __init sysfs_init(void) 171 { 172 int err = -ENOMEM; 173 174 sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache", 175 sizeof(struct sysfs_dirent), 176 0, 0, NULL); 177 if (!sysfs_dir_cachep) 178 goto out; 179 180 err = sysfs_inode_init(); 181 if (err) 182 goto out_err; 183 184 err = register_filesystem(&sysfs_fs_type); 185 if (!err) { 186 sysfs_mnt = kern_mount(&sysfs_fs_type); 187 if (IS_ERR(sysfs_mnt)) { 188 printk(KERN_ERR "sysfs: could not mount!\n"); 189 err = PTR_ERR(sysfs_mnt); 190 sysfs_mnt = NULL; 191 unregister_filesystem(&sysfs_fs_type); 192 goto out_err; 193 } 194 } else 195 goto out_err; 196 out: 197 return err; 198 out_err: 199 kmem_cache_destroy(sysfs_dir_cachep); 200 sysfs_dir_cachep = NULL; 201 goto out; 202 } 203 204 #undef sysfs_get 205 struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd) 206 { 207 return __sysfs_get(sd); 208 } 209 EXPORT_SYMBOL_GPL(sysfs_get); 210 211 #undef sysfs_put 212 void sysfs_put(struct sysfs_dirent *sd) 213 { 214 __sysfs_put(sd); 215 } 216 EXPORT_SYMBOL_GPL(sysfs_put); 217