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_mount; 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 .delete_inode = sysfs_delete_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 int sysfs_get_sb(struct file_system_type *fs_type, 99 int flags, const char *dev_name, void *data, struct vfsmount *mnt) 100 { 101 struct sysfs_super_info *info; 102 enum kobj_ns_type type; 103 struct super_block *sb; 104 int error; 105 106 error = -ENOMEM; 107 info = kzalloc(sizeof(*info), GFP_KERNEL); 108 if (!info) 109 goto out; 110 111 for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++) 112 info->ns[type] = kobj_ns_current(type); 113 114 sb = sget(fs_type, sysfs_test_super, sysfs_set_super, info); 115 if (IS_ERR(sb) || sb->s_fs_info != info) 116 kfree(info); 117 if (IS_ERR(sb)) { 118 error = PTR_ERR(sb); 119 goto out; 120 } 121 if (!sb->s_root) { 122 sb->s_flags = flags; 123 error = sysfs_fill_super(sb, data, flags & MS_SILENT ? 1 : 0); 124 if (error) { 125 deactivate_locked_super(sb); 126 goto out; 127 } 128 sb->s_flags |= MS_ACTIVE; 129 } 130 131 simple_set_mnt(mnt, sb); 132 error = 0; 133 out: 134 return error; 135 } 136 137 static void sysfs_kill_sb(struct super_block *sb) 138 { 139 struct sysfs_super_info *info = sysfs_info(sb); 140 141 /* 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 kfree(info); 146 } 147 148 static struct file_system_type sysfs_fs_type = { 149 .name = "sysfs", 150 .get_sb = sysfs_get_sb, 151 .kill_sb = sysfs_kill_sb, 152 }; 153 154 void sysfs_exit_ns(enum kobj_ns_type type, const void *ns) 155 { 156 struct super_block *sb; 157 158 mutex_lock(&sysfs_mutex); 159 spin_lock(&sb_lock); 160 list_for_each_entry(sb, &sysfs_fs_type.fs_supers, s_instances) { 161 struct sysfs_super_info *info = sysfs_info(sb); 162 /* 163 * If we see a superblock on the fs_supers/s_instances 164 * list the unmount has not completed and sb->s_fs_info 165 * points to a valid struct sysfs_super_info. 166 */ 167 /* Ignore superblocks with the wrong ns */ 168 if (info->ns[type] != ns) 169 continue; 170 info->ns[type] = NULL; 171 } 172 spin_unlock(&sb_lock); 173 mutex_unlock(&sysfs_mutex); 174 } 175 176 int __init sysfs_init(void) 177 { 178 int err = -ENOMEM; 179 180 sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache", 181 sizeof(struct sysfs_dirent), 182 0, 0, NULL); 183 if (!sysfs_dir_cachep) 184 goto out; 185 186 err = sysfs_inode_init(); 187 if (err) 188 goto out_err; 189 190 err = register_filesystem(&sysfs_fs_type); 191 if (!err) { 192 sysfs_mount = kern_mount(&sysfs_fs_type); 193 if (IS_ERR(sysfs_mount)) { 194 printk(KERN_ERR "sysfs: could not mount!\n"); 195 err = PTR_ERR(sysfs_mount); 196 sysfs_mount = NULL; 197 unregister_filesystem(&sysfs_fs_type); 198 goto out_err; 199 } 200 } else 201 goto out_err; 202 out: 203 return err; 204 out_err: 205 kmem_cache_destroy(sysfs_dir_cachep); 206 sysfs_dir_cachep = NULL; 207 goto out; 208 } 209 210 #undef sysfs_get 211 struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd) 212 { 213 return __sysfs_get(sd); 214 } 215 EXPORT_SYMBOL_GPL(sysfs_get); 216 217 #undef sysfs_put 218 void sysfs_put(struct sysfs_dirent *sd) 219 { 220 __sysfs_put(sd); 221 } 222 EXPORT_SYMBOL_GPL(sysfs_put); 223