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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 void free_sysfs_super_info(struct sysfs_super_info *info) |
99 | { |
100 | int type; |
101 | for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++) |
102 | kobj_ns_drop(type, info->ns[type]); |
103 | kfree(info); |
104 | } |
105 | |
106 | static struct dentry *sysfs_mount(struct file_system_type *fs_type, |
107 | int flags, const char *dev_name, void *data) |
108 | { |
109 | struct sysfs_super_info *info; |
110 | enum kobj_ns_type type; |
111 | struct super_block *sb; |
112 | int error; |
113 | |
114 | info = kzalloc(sizeof(*info), GFP_KERNEL); |
115 | if (!info) |
116 | return ERR_PTR(-ENOMEM); |
117 | |
118 | for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++) |
119 | info->ns[type] = kobj_ns_grab_current(type); |
120 | |
121 | sb = sget(fs_type, sysfs_test_super, sysfs_set_super, info); |
122 | if (IS_ERR(sb) || sb->s_fs_info != info) |
123 | free_sysfs_super_info(info); |
124 | if (IS_ERR(sb)) |
125 | return ERR_CAST(sb); |
126 | if (!sb->s_root) { |
127 | sb->s_flags = flags; |
128 | error = sysfs_fill_super(sb, data, flags & MS_SILENT ? 1 : 0); |
129 | if (error) { |
130 | deactivate_locked_super(sb); |
131 | return ERR_PTR(error); |
132 | } |
133 | sb->s_flags |= MS_ACTIVE; |
134 | } |
135 | |
136 | return dget(sb->s_root); |
137 | } |
138 | |
139 | static void sysfs_kill_sb(struct super_block *sb) |
140 | { |
141 | struct sysfs_super_info *info = sysfs_info(sb); |
142 | /* Remove the superblock from fs_supers/s_instances |
143 | * so we can't find it, before freeing sysfs_super_info. |
144 | */ |
145 | kill_anon_super(sb); |
146 | free_sysfs_super_info(info); |
147 | } |
148 | |
149 | static struct file_system_type sysfs_fs_type = { |
150 | .name = "sysfs", |
151 | .mount = sysfs_mount, |
152 | .kill_sb = sysfs_kill_sb, |
153 | }; |
154 | |
155 | int __init sysfs_init(void) |
156 | { |
157 | int err = -ENOMEM; |
158 | |
159 | sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache", |
160 | sizeof(struct sysfs_dirent), |
161 | 0, 0, NULL); |
162 | if (!sysfs_dir_cachep) |
163 | goto out; |
164 | |
165 | err = sysfs_inode_init(); |
166 | if (err) |
167 | goto out_err; |
168 | |
169 | err = register_filesystem(&sysfs_fs_type); |
170 | if (!err) { |
171 | sysfs_mnt = kern_mount(&sysfs_fs_type); |
172 | if (IS_ERR(sysfs_mnt)) { |
173 | printk(KERN_ERR "sysfs: could not mount!\n"); |
174 | err = PTR_ERR(sysfs_mnt); |
175 | sysfs_mnt = NULL; |
176 | unregister_filesystem(&sysfs_fs_type); |
177 | goto out_err; |
178 | } |
179 | } else |
180 | goto out_err; |
181 | out: |
182 | return err; |
183 | out_err: |
184 | kmem_cache_destroy(sysfs_dir_cachep); |
185 | sysfs_dir_cachep = NULL; |
186 | goto out; |
187 | } |
188 | |
189 | #undef sysfs_get |
190 | struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd) |
191 | { |
192 | return __sysfs_get(sd); |
193 | } |
194 | EXPORT_SYMBOL_GPL(sysfs_get); |
195 | |
196 | #undef sysfs_put |
197 | void sysfs_put(struct sysfs_dirent *sd) |
198 | { |
199 | __sysfs_put(sd); |
200 | } |
201 | EXPORT_SYMBOL_GPL(sysfs_put); |
202 |
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