Commit | Line | Data |
---|---|---|
1da177e4 | 1 | /* |
6d66f5cd TH |
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. | |
1da177e4 LT |
11 | */ |
12 | ||
6b8fbde4 | 13 | #define DEBUG |
1da177e4 LT |
14 | |
15 | #include <linux/fs.h> | |
16 | #include <linux/mount.h> | |
17 | #include <linux/pagemap.h> | |
18 | #include <linux/init.h> | |
f1282c84 | 19 | #include <linux/module.h> |
8231f2f9 | 20 | #include <linux/magic.h> |
5a0e3ad6 | 21 | #include <linux/slab.h> |
87a8ebd6 | 22 | #include <linux/user_namespace.h> |
1da177e4 LT |
23 | |
24 | #include "sysfs.h" | |
25 | ||
1da177e4 | 26 | |
d0e46f88 | 27 | static struct vfsmount *sysfs_mnt; |
e18b890b | 28 | struct kmem_cache *sysfs_dir_cachep; |
1da177e4 | 29 | |
ee9b6d61 | 30 | static const struct super_operations sysfs_ops = { |
1da177e4 | 31 | .statfs = simple_statfs, |
90bc6135 | 32 | .drop_inode = generic_delete_inode, |
01cd9fef | 33 | .evict_inode = sysfs_evict_inode, |
1da177e4 LT |
34 | }; |
35 | ||
51225039 | 36 | struct sysfs_dirent sysfs_root = { |
dc2f75f0 | 37 | .s_name = "", |
13b3086d | 38 | .s_count = ATOMIC_INIT(1), |
3ff195b0 | 39 | .s_flags = SYSFS_DIR | (KOBJ_NS_TYPE_NONE << SYSFS_NS_TYPE_SHIFT), |
c56d8a73 | 40 | .s_mode = S_IFDIR | S_IRUGO | S_IXUGO, |
dc351252 | 41 | .s_ino = 1, |
1da177e4 LT |
42 | }; |
43 | ||
44 | static int sysfs_fill_super(struct super_block *sb, void *data, int silent) | |
45 | { | |
46 | struct inode *inode; | |
47 | struct dentry *root; | |
48 | ||
49 | sb->s_blocksize = PAGE_CACHE_SIZE; | |
50 | sb->s_blocksize_bits = PAGE_CACHE_SHIFT; | |
51 | sb->s_magic = SYSFS_MAGIC; | |
52 | sb->s_op = &sysfs_ops; | |
53 | sb->s_time_gran = 1; | |
1da177e4 | 54 | |
e080e436 | 55 | /* get root inode, initialize and unlock it */ |
4a67a1bc | 56 | mutex_lock(&sysfs_mutex); |
fac2622b | 57 | inode = sysfs_get_inode(sb, &sysfs_root); |
4a67a1bc | 58 | mutex_unlock(&sysfs_mutex); |
fc9f54b9 | 59 | if (!inode) { |
1da177e4 LT |
60 | pr_debug("sysfs: could not get root inode\n"); |
61 | return -ENOMEM; | |
62 | } | |
63 | ||
e080e436 | 64 | /* instantiate and link root dentry */ |
48fde701 | 65 | root = d_make_root(inode); |
1da177e4 | 66 | if (!root) { |
8e24eea7 | 67 | pr_debug("%s: could not get root dentry!\n",__func__); |
1da177e4 LT |
68 | return -ENOMEM; |
69 | } | |
70 | root->d_fsdata = &sysfs_root; | |
71 | sb->s_root = root; | |
469796d1 | 72 | sb->s_d_op = &sysfs_dentry_ops; |
1da177e4 LT |
73 | return 0; |
74 | } | |
75 | ||
9e7fdd25 EB |
76 | static int sysfs_test_super(struct super_block *sb, void *data) |
77 | { | |
78 | struct sysfs_super_info *sb_info = sysfs_info(sb); | |
79 | struct sysfs_super_info *info = data; | |
3ff195b0 | 80 | enum kobj_ns_type type; |
9e7fdd25 | 81 | int found = 1; |
3ff195b0 EB |
82 | |
83 | for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++) { | |
84 | if (sb_info->ns[type] != info->ns[type]) | |
85 | found = 0; | |
86 | } | |
9e7fdd25 EB |
87 | return found; |
88 | } | |
89 | ||
90 | static int sysfs_set_super(struct super_block *sb, void *data) | |
91 | { | |
92 | int error; | |
93 | error = set_anon_super(sb, data); | |
94 | if (!error) | |
95 | sb->s_fs_info = data; | |
96 | return error; | |
97 | } | |
98 | ||
a685e089 AV |
99 | static void free_sysfs_super_info(struct sysfs_super_info *info) |
100 | { | |
101 | int type; | |
102 | for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++) | |
103 | kobj_ns_drop(type, info->ns[type]); | |
104 | kfree(info); | |
105 | } | |
106 | ||
d0e46f88 AV |
107 | static struct dentry *sysfs_mount(struct file_system_type *fs_type, |
108 | int flags, const char *dev_name, void *data) | |
1da177e4 | 109 | { |
9e7fdd25 | 110 | struct sysfs_super_info *info; |
3ff195b0 | 111 | enum kobj_ns_type type; |
9e7fdd25 EB |
112 | struct super_block *sb; |
113 | int error; | |
114 | ||
87a8ebd6 EB |
115 | if (!(flags & MS_KERNMOUNT) && !current_user_ns()->may_mount_sysfs) |
116 | return ERR_PTR(-EPERM); | |
117 | ||
9e7fdd25 EB |
118 | info = kzalloc(sizeof(*info), GFP_KERNEL); |
119 | if (!info) | |
d0e46f88 | 120 | return ERR_PTR(-ENOMEM); |
3ff195b0 EB |
121 | |
122 | for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++) | |
a685e089 | 123 | info->ns[type] = kobj_ns_grab_current(type); |
3ff195b0 | 124 | |
9249e17f | 125 | sb = sget(fs_type, sysfs_test_super, sysfs_set_super, flags, info); |
9e7fdd25 | 126 | if (IS_ERR(sb) || sb->s_fs_info != info) |
a685e089 | 127 | free_sysfs_super_info(info); |
d0e46f88 AV |
128 | if (IS_ERR(sb)) |
129 | return ERR_CAST(sb); | |
9e7fdd25 | 130 | if (!sb->s_root) { |
9e7fdd25 EB |
131 | error = sysfs_fill_super(sb, data, flags & MS_SILENT ? 1 : 0); |
132 | if (error) { | |
133 | deactivate_locked_super(sb); | |
d0e46f88 | 134 | return ERR_PTR(error); |
9e7fdd25 EB |
135 | } |
136 | sb->s_flags |= MS_ACTIVE; | |
137 | } | |
138 | ||
d0e46f88 | 139 | return dget(sb->s_root); |
9e7fdd25 EB |
140 | } |
141 | ||
142 | static void sysfs_kill_sb(struct super_block *sb) | |
143 | { | |
144 | struct sysfs_super_info *info = sysfs_info(sb); | |
68d75ed4 EB |
145 | /* Remove the superblock from fs_supers/s_instances |
146 | * so we can't find it, before freeing sysfs_super_info. | |
147 | */ | |
9e7fdd25 | 148 | kill_anon_super(sb); |
a685e089 | 149 | free_sysfs_super_info(info); |
1da177e4 LT |
150 | } |
151 | ||
152 | static struct file_system_type sysfs_fs_type = { | |
153 | .name = "sysfs", | |
d0e46f88 | 154 | .mount = sysfs_mount, |
9e7fdd25 | 155 | .kill_sb = sysfs_kill_sb, |
4f326c00 | 156 | .fs_flags = FS_USERNS_MOUNT, |
1da177e4 LT |
157 | }; |
158 | ||
159 | int __init sysfs_init(void) | |
160 | { | |
161 | int err = -ENOMEM; | |
162 | ||
163 | sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache", | |
164 | sizeof(struct sysfs_dirent), | |
20c2df83 | 165 | 0, 0, NULL); |
1da177e4 LT |
166 | if (!sysfs_dir_cachep) |
167 | goto out; | |
168 | ||
e0bf68dd PZ |
169 | err = sysfs_inode_init(); |
170 | if (err) | |
171 | goto out_err; | |
172 | ||
1da177e4 LT |
173 | err = register_filesystem(&sysfs_fs_type); |
174 | if (!err) { | |
d0e46f88 AV |
175 | sysfs_mnt = kern_mount(&sysfs_fs_type); |
176 | if (IS_ERR(sysfs_mnt)) { | |
1da177e4 | 177 | printk(KERN_ERR "sysfs: could not mount!\n"); |
d0e46f88 AV |
178 | err = PTR_ERR(sysfs_mnt); |
179 | sysfs_mnt = NULL; | |
1da177e4 LT |
180 | unregister_filesystem(&sysfs_fs_type); |
181 | goto out_err; | |
182 | } | |
183 | } else | |
184 | goto out_err; | |
185 | out: | |
186 | return err; | |
187 | out_err: | |
188 | kmem_cache_destroy(sysfs_dir_cachep); | |
189 | sysfs_dir_cachep = NULL; | |
190 | goto out; | |
191 | } | |
f1282c84 NB |
192 | |
193 | #undef sysfs_get | |
194 | struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd) | |
195 | { | |
196 | return __sysfs_get(sd); | |
197 | } | |
198 | EXPORT_SYMBOL_GPL(sysfs_get); | |
199 | ||
200 | #undef sysfs_put | |
201 | void sysfs_put(struct sysfs_dirent *sd) | |
202 | { | |
203 | __sysfs_put(sd); | |
204 | } | |
205 | EXPORT_SYMBOL_GPL(sysfs_put); |