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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
Tejun Heo6d66f5c2007-09-20 17:31:38 +09002 * 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.
Linus Torvalds1da177e2005-04-16 15:20:36 -070011 */
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>
Neil Brownf1282c82008-07-16 08:58:04 +100019#include <linux/module.h>
Qinghuang Feng8231f2f2009-01-14 15:45:13 +080020#include <linux/magic.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090021#include <linux/slab.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070022
23#include "sysfs.h"
24
Linus Torvalds1da177e2005-04-16 15:20:36 -070025
Eric W. Biederman7d0c7d62007-08-20 21:36:30 +090026static struct vfsmount *sysfs_mount;
Christoph Lametere18b8902006-12-06 20:33:20 -080027struct kmem_cache *sysfs_dir_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -070028
Josef 'Jeff' Sipekee9b6d62007-02-12 00:55:41 -080029static const struct super_operations sysfs_ops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -070030 .statfs = simple_statfs,
Eric W. Biederman90bc6132007-07-31 19:15:08 +090031 .drop_inode = generic_delete_inode,
Al Viro01cd9fe2010-06-04 22:21:54 -040032 .evict_inode = sysfs_evict_inode,
Linus Torvalds1da177e2005-04-16 15:20:36 -070033};
34
Tejun Heo51225032007-06-14 04:27:25 +090035struct sysfs_dirent sysfs_root = {
Tejun Heodc2f75f2007-09-20 16:05:12 +090036 .s_name = "",
Tejun Heo13b30862007-06-14 03:45:14 +090037 .s_count = ATOMIC_INIT(1),
Eric W. Biederman3ff195b2010-03-30 11:31:26 -070038 .s_flags = SYSFS_DIR | (KOBJ_NS_TYPE_NONE << SYSFS_NS_TYPE_SHIFT),
Tejun Heofc9f54b2007-06-14 03:45:17 +090039 .s_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
Eric Sandeendc351252007-06-11 14:02:45 +090040 .s_ino = 1,
Linus Torvalds1da177e2005-04-16 15:20:36 -070041};
42
43static 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;
Linus Torvalds1da177e2005-04-16 15:20:36 -070053
Tejun Heoe080e432007-07-18 14:29:06 +090054 /* get root inode, initialize and unlock it */
Eric W. Biederman4a67a1b2009-01-21 11:55:11 -080055 mutex_lock(&sysfs_mutex);
Eric W. Biedermanfac26222010-02-12 19:22:27 -080056 inode = sysfs_get_inode(sb, &sysfs_root);
Eric W. Biederman4a67a1b2009-01-21 11:55:11 -080057 mutex_unlock(&sysfs_mutex);
Tejun Heofc9f54b2007-06-14 03:45:17 +090058 if (!inode) {
Linus Torvalds1da177e2005-04-16 15:20:36 -070059 pr_debug("sysfs: could not get root inode\n");
60 return -ENOMEM;
61 }
62
Tejun Heoe080e432007-07-18 14:29:06 +090063 /* instantiate and link root dentry */
Linus Torvalds1da177e2005-04-16 15:20:36 -070064 root = d_alloc_root(inode);
65 if (!root) {
Harvey Harrison8e24eea2008-04-30 00:55:09 -070066 pr_debug("%s: could not get root dentry!\n",__func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -070067 iput(inode);
68 return -ENOMEM;
69 }
70 root->d_fsdata = &sysfs_root;
71 sb->s_root = root;
72 return 0;
73}
74
Eric W. Biederman9e7fdd22010-03-30 11:31:24 -070075static 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;
Eric W. Biederman3ff195b2010-03-30 11:31:26 -070079 enum kobj_ns_type type;
Eric W. Biederman9e7fdd22010-03-30 11:31:24 -070080 int found = 1;
Eric W. Biederman3ff195b2010-03-30 11:31:26 -070081
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 }
Eric W. Biederman9e7fdd22010-03-30 11:31:24 -070086 return found;
87}
88
89static 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
David Howells454e2392006-06-23 02:02:57 -070098static int sysfs_get_sb(struct file_system_type *fs_type,
99 int flags, const char *dev_name, void *data, struct vfsmount *mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100{
Eric W. Biederman9e7fdd22010-03-30 11:31:24 -0700101 struct sysfs_super_info *info;
Eric W. Biederman3ff195b2010-03-30 11:31:26 -0700102 enum kobj_ns_type type;
Eric W. Biederman9e7fdd22010-03-30 11:31:24 -0700103 struct super_block *sb;
104 int error;
105
106 error = -ENOMEM;
107 info = kzalloc(sizeof(*info), GFP_KERNEL);
108 if (!info)
109 goto out;
Eric W. Biederman3ff195b2010-03-30 11:31:26 -0700110
111 for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++)
112 info->ns[type] = kobj_ns_current(type);
113
Eric W. Biederman9e7fdd22010-03-30 11:31:24 -0700114 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)) {
Eric W. Biederman9e7fdd22010-03-30 11:31:24 -0700118 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;
133out:
134 return error;
135}
136
137static void sysfs_kill_sb(struct super_block *sb)
138{
139 struct sysfs_super_info *info = sysfs_info(sb);
140
Eric W. Biederman68d75ed2010-05-18 12:58:33 -0700141 /* Remove the superblock from fs_supers/s_instances
142 * so we can't find it, before freeing sysfs_super_info.
143 */
Eric W. Biederman9e7fdd22010-03-30 11:31:24 -0700144 kill_anon_super(sb);
145 kfree(info);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146}
147
148static struct file_system_type sysfs_fs_type = {
149 .name = "sysfs",
150 .get_sb = sysfs_get_sb,
Eric W. Biederman9e7fdd22010-03-30 11:31:24 -0700151 .kill_sb = sysfs_kill_sb,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152};
153
Eric W. Biederman3ff195b2010-03-30 11:31:26 -0700154void 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);
Eric W. Biederman68d75ed2010-05-18 12:58:33 -0700162 /*
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 */
Eric W. Biederman3ff195b2010-03-30 11:31:26 -0700167 /* 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
Linus Torvalds1da177e2005-04-16 15:20:36 -0700176int __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),
Paul Mundt20c2df82007-07-20 10:11:58 +0900182 0, 0, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183 if (!sysfs_dir_cachep)
184 goto out;
185
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -0700186 err = sysfs_inode_init();
187 if (err)
188 goto out_err;
189
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190 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;
202out:
203 return err;
204out_err:
205 kmem_cache_destroy(sysfs_dir_cachep);
206 sysfs_dir_cachep = NULL;
207 goto out;
208}
Neil Brownf1282c82008-07-16 08:58:04 +1000209
210#undef sysfs_get
211struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd)
212{
213 return __sysfs_get(sd);
214}
215EXPORT_SYMBOL_GPL(sysfs_get);
216
217#undef sysfs_put
218void sysfs_put(struct sysfs_dirent *sd)
219{
220 __sysfs_put(sd);
221}
222EXPORT_SYMBOL_GPL(sysfs_put);