sysfs: make sysfs_root a regular directory dirent
[linux-2.6] / fs / sysfs / mount.c
1 /*
2  * mount.c - operations for initializing and mounting sysfs.
3  */
4
5 #define DEBUG 
6
7 #include <linux/fs.h>
8 #include <linux/mount.h>
9 #include <linux/pagemap.h>
10 #include <linux/init.h>
11
12 #include "sysfs.h"
13
14 /* Random magic number */
15 #define SYSFS_MAGIC 0x62656572
16
17 static struct vfsmount *sysfs_mount;
18 struct super_block * sysfs_sb = NULL;
19 struct kmem_cache *sysfs_dir_cachep;
20
21 static const struct super_operations sysfs_ops = {
22         .statfs         = simple_statfs,
23         .drop_inode     = generic_delete_inode,
24 };
25
26 struct sysfs_dirent sysfs_root = {
27         .s_name         = "",
28         .s_count        = ATOMIC_INIT(1),
29         .s_flags        = SYSFS_DIR,
30         .s_mode         = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
31         .s_ino          = 1,
32 };
33
34 static int sysfs_fill_super(struct super_block *sb, void *data, int silent)
35 {
36         struct inode *inode;
37         struct dentry *root;
38
39         sb->s_blocksize = PAGE_CACHE_SIZE;
40         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
41         sb->s_magic = SYSFS_MAGIC;
42         sb->s_op = &sysfs_ops;
43         sb->s_time_gran = 1;
44         sysfs_sb = sb;
45
46         /* get root inode, initialize and unlock it */
47         inode = sysfs_get_inode(&sysfs_root);
48         if (!inode) {
49                 pr_debug("sysfs: could not get root inode\n");
50                 return -ENOMEM;
51         }
52
53         /* instantiate and link root dentry */
54         root = d_alloc_root(inode);
55         if (!root) {
56                 pr_debug("%s: could not get root dentry!\n",__FUNCTION__);
57                 iput(inode);
58                 return -ENOMEM;
59         }
60         root->d_fsdata = &sysfs_root;
61         sb->s_root = root;
62         return 0;
63 }
64
65 static int sysfs_get_sb(struct file_system_type *fs_type,
66         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
67 {
68         return get_sb_single(fs_type, flags, data, sysfs_fill_super, mnt);
69 }
70
71 static struct file_system_type sysfs_fs_type = {
72         .name           = "sysfs",
73         .get_sb         = sysfs_get_sb,
74         .kill_sb        = kill_anon_super,
75 };
76
77 int __init sysfs_init(void)
78 {
79         int err = -ENOMEM;
80
81         sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache",
82                                               sizeof(struct sysfs_dirent),
83                                               0, 0, NULL);
84         if (!sysfs_dir_cachep)
85                 goto out;
86
87         err = register_filesystem(&sysfs_fs_type);
88         if (!err) {
89                 sysfs_mount = kern_mount(&sysfs_fs_type);
90                 if (IS_ERR(sysfs_mount)) {
91                         printk(KERN_ERR "sysfs: could not mount!\n");
92                         err = PTR_ERR(sysfs_mount);
93                         sysfs_mount = NULL;
94                         unregister_filesystem(&sysfs_fs_type);
95                         goto out_err;
96                 }
97         } else
98                 goto out_err;
99 out:
100         return err;
101 out_err:
102         kmem_cache_destroy(sysfs_dir_cachep);
103         sysfs_dir_cachep = NULL;
104         goto out;
105 }