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#include <asm/semaphore.h>
12
13#include "sysfs.h"
14
15/* Random magic number */
16#define SYSFS_MAGIC 0x62656572
17
18struct vfsmount *sysfs_mount;
19struct super_block * sysfs_sb = NULL;
20struct kmem_cache *sysfs_dir_cachep;
21
22static void sysfs_clear_inode(struct inode *inode);
23
24static const struct super_operations sysfs_ops = {
25	.statfs		= simple_statfs,
26	.drop_inode	= sysfs_delete_inode,
27	.clear_inode	= sysfs_clear_inode,
28};
29
30static struct sysfs_dirent sysfs_root = {
31	.s_sibling	= LIST_HEAD_INIT(sysfs_root.s_sibling),
32	.s_children	= LIST_HEAD_INIT(sysfs_root.s_children),
33	.s_element	= NULL,
34	.s_type		= SYSFS_ROOT,
35	.s_iattr	= NULL,
36	.s_ino		= 1,
37};
38
39static void sysfs_clear_inode(struct inode *inode)
40{
41	kfree(inode->i_private);
42}
43
44static 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;
54	sysfs_sb = sb;
55
56	inode = sysfs_new_inode(S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
57				 &sysfs_root);
58	if (inode) {
59		inode->i_op = &sysfs_dir_inode_operations;
60		inode->i_fop = &sysfs_dir_operations;
61		/* directory inodes start off with i_nlink == 2 (for "." entry) */
62		inc_nlink(inode);
63	} else {
64		pr_debug("sysfs: could not get root inode\n");
65		return -ENOMEM;
66	}
67
68	root = d_alloc_root(inode);
69	if (!root) {
70		pr_debug("%s: could not get root dentry!\n",__FUNCTION__);
71		iput(inode);
72		return -ENOMEM;
73	}
74	root->d_fsdata = &sysfs_root;
75	sb->s_root = root;
76	return 0;
77}
78
79static int sysfs_get_sb(struct file_system_type *fs_type,
80	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
81{
82	return get_sb_single(fs_type, flags, data, sysfs_fill_super, mnt);
83}
84
85static struct file_system_type sysfs_fs_type = {
86	.name		= "sysfs",
87	.get_sb		= sysfs_get_sb,
88	.kill_sb	= kill_litter_super,
89};
90
91int __init sysfs_init(void)
92{
93	int err = -ENOMEM;
94
95	sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache",
96					      sizeof(struct sysfs_dirent),
97					      0, 0, NULL, NULL);
98	if (!sysfs_dir_cachep)
99		goto out;
100
101	err = register_filesystem(&sysfs_fs_type);
102	if (!err) {
103		sysfs_mount = kern_mount(&sysfs_fs_type);
104		if (IS_ERR(sysfs_mount)) {
105			printk(KERN_ERR "sysfs: could not mount!\n");
106			err = PTR_ERR(sysfs_mount);
107			sysfs_mount = NULL;
108			unregister_filesystem(&sysfs_fs_type);
109			goto out_err;
110		}
111	} else
112		goto out_err;
113out:
114	return err;
115out_err:
116	kmem_cache_destroy(sysfs_dir_cachep);
117	sysfs_dir_cachep = NULL;
118	goto out;
119}
120