xref: /openbmc/linux/fs/sysfs/mount.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
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 struct vfsmount *sysfs_mount;
18 struct super_block * sysfs_sb = NULL;
19 kmem_cache_t *sysfs_dir_cachep;
20 
21 static struct super_operations sysfs_ops = {
22 	.statfs		= simple_statfs,
23 	.drop_inode	= generic_delete_inode,
24 };
25 
26 static struct sysfs_dirent sysfs_root = {
27 	.s_sibling	= LIST_HEAD_INIT(sysfs_root.s_sibling),
28 	.s_children	= LIST_HEAD_INIT(sysfs_root.s_children),
29 	.s_element	= NULL,
30 	.s_type		= SYSFS_ROOT,
31 	.s_iattr	= NULL,
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 	inode = sysfs_new_inode(S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
47 				 &sysfs_root);
48 	if (inode) {
49 		inode->i_op = &sysfs_dir_inode_operations;
50 		inode->i_fop = &sysfs_dir_operations;
51 		/* directory inodes start off with i_nlink == 2 (for "." entry) */
52 		inode->i_nlink++;
53 	} else {
54 		pr_debug("sysfs: could not get root inode\n");
55 		return -ENOMEM;
56 	}
57 
58 	root = d_alloc_root(inode);
59 	if (!root) {
60 		pr_debug("%s: could not get root dentry!\n",__FUNCTION__);
61 		iput(inode);
62 		return -ENOMEM;
63 	}
64 	root->d_fsdata = &sysfs_root;
65 	sb->s_root = root;
66 	return 0;
67 }
68 
69 static struct super_block *sysfs_get_sb(struct file_system_type *fs_type,
70 	int flags, const char *dev_name, void *data)
71 {
72 	return get_sb_single(fs_type, flags, data, sysfs_fill_super);
73 }
74 
75 static struct file_system_type sysfs_fs_type = {
76 	.name		= "sysfs",
77 	.get_sb		= sysfs_get_sb,
78 	.kill_sb	= kill_litter_super,
79 };
80 
81 int __init sysfs_init(void)
82 {
83 	int err = -ENOMEM;
84 
85 	sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache",
86 					      sizeof(struct sysfs_dirent),
87 					      0, 0, NULL, NULL);
88 	if (!sysfs_dir_cachep)
89 		goto out;
90 
91 	err = register_filesystem(&sysfs_fs_type);
92 	if (!err) {
93 		sysfs_mount = kern_mount(&sysfs_fs_type);
94 		if (IS_ERR(sysfs_mount)) {
95 			printk(KERN_ERR "sysfs: could not mount!\n");
96 			err = PTR_ERR(sysfs_mount);
97 			sysfs_mount = NULL;
98 			unregister_filesystem(&sysfs_fs_type);
99 			goto out_err;
100 		}
101 	} else
102 		goto out_err;
103 out:
104 	return err;
105 out_err:
106 	kmem_cache_destroy(sysfs_dir_cachep);
107 	sysfs_dir_cachep = NULL;
108 	goto out;
109 }
110