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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
26static struct vfsmount *sysfs_mnt;
27struct kmem_cache *sysfs_dir_cachep;
28
29static const struct super_operations sysfs_ops = {
30 .statfs = simple_statfs,
31 .drop_inode = generic_delete_inode,
32 .evict_inode = sysfs_evict_inode,
33};
34
35struct 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_IRUGO | S_IXUGO,
40 .s_ino = 1,
41};
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;
53
54
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
64 root = d_make_root(inode);
65 if (!root) {
66 pr_debug("%s: could not get root dentry!\n",__func__);
67 return -ENOMEM;
68 }
69 root->d_fsdata = &sysfs_root;
70 sb->s_root = root;
71 sb->s_d_op = &sysfs_dentry_ops;
72 return 0;
73}
74
75static 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
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
98static 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
106static 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, flags, 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 error = sysfs_fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
128 if (error) {
129 deactivate_locked_super(sb);
130 return ERR_PTR(error);
131 }
132 sb->s_flags |= MS_ACTIVE;
133 }
134
135 return dget(sb->s_root);
136}
137
138static void sysfs_kill_sb(struct super_block *sb)
139{
140 struct sysfs_super_info *info = sysfs_info(sb);
141
142
143
144 kill_anon_super(sb);
145 free_sysfs_super_info(info);
146}
147
148static struct file_system_type sysfs_fs_type = {
149 .name = "sysfs",
150 .mount = sysfs_mount,
151 .kill_sb = sysfs_kill_sb,
152 .fs_flags = FS_USERNS_MOUNT,
153};
154
155int __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;
181out:
182 return err;
183out_err:
184 kmem_cache_destroy(sysfs_dir_cachep);
185 sysfs_dir_cachep = NULL;
186 goto out;
187}
188
189#undef sysfs_get
190struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd)
191{
192 return __sysfs_get(sd);
193}
194EXPORT_SYMBOL_GPL(sysfs_get);
195
196#undef sysfs_put
197void sysfs_put(struct sysfs_dirent *sd)
198{
199 __sysfs_put(sd);
200}
201EXPORT_SYMBOL_GPL(sysfs_put);
202
