xref: /openbmc/linux/fs/sysfs/mount.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
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 
18 struct vfsmount *sysfs_mount;
19 struct super_block * sysfs_sb = NULL;
20 struct kmem_cache *sysfs_dir_cachep;
21 
22 static void sysfs_clear_inode(struct inode *inode);
23 
24 static const struct super_operations sysfs_ops = {
25 	.statfs		= simple_statfs,
26 	.drop_inode	= sysfs_delete_inode,
27 	.clear_inode	= sysfs_clear_inode,
28 };
29 
30 static 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 };
37 
38 static void sysfs_clear_inode(struct inode *inode)
39 {
40 	kfree(inode->i_private);
41 }
42 
43 static 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 	sysfs_sb = sb;
54 
55 	inode = sysfs_new_inode(S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
56 				 &sysfs_root);
57 	if (inode) {
58 		inode->i_op = &sysfs_dir_inode_operations;
59 		inode->i_fop = &sysfs_dir_operations;
60 		/* directory inodes start off with i_nlink == 2 (for "." entry) */
61 		inc_nlink(inode);
62 	} else {
63 		pr_debug("sysfs: could not get root inode\n");
64 		return -ENOMEM;
65 	}
66 
67 	root = d_alloc_root(inode);
68 	if (!root) {
69 		pr_debug("%s: could not get root dentry!\n",__FUNCTION__);
70 		iput(inode);
71 		return -ENOMEM;
72 	}
73 	root->d_fsdata = &sysfs_root;
74 	sb->s_root = root;
75 	return 0;
76 }
77 
78 static int sysfs_get_sb(struct file_system_type *fs_type,
79 	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
80 {
81 	return get_sb_single(fs_type, flags, data, sysfs_fill_super, mnt);
82 }
83 
84 static struct file_system_type sysfs_fs_type = {
85 	.name		= "sysfs",
86 	.get_sb		= sysfs_get_sb,
87 	.kill_sb	= kill_litter_super,
88 };
89 
90 int __init sysfs_init(void)
91 {
92 	int err = -ENOMEM;
93 
94 	sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache",
95 					      sizeof(struct sysfs_dirent),
96 					      0, 0, NULL, NULL);
97 	if (!sysfs_dir_cachep)
98 		goto out;
99 
100 	err = register_filesystem(&sysfs_fs_type);
101 	if (!err) {
102 		sysfs_mount = kern_mount(&sysfs_fs_type);
103 		if (IS_ERR(sysfs_mount)) {
104 			printk(KERN_ERR "sysfs: could not mount!\n");
105 			err = PTR_ERR(sysfs_mount);
106 			sysfs_mount = NULL;
107 			unregister_filesystem(&sysfs_fs_type);
108 			goto out_err;
109 		}
110 	} else
111 		goto out_err;
112 out:
113 	return err;
114 out_err:
115 	kmem_cache_destroy(sysfs_dir_cachep);
116 	sysfs_dir_cachep = NULL;
117 	goto out;
118 }
119