xref: /openbmc/linux/fs/sysfs/mount.c (revision c21b37f6)
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 const struct super_operations sysfs_ops = {
23 	.statfs		= simple_statfs,
24 	.drop_inode	= sysfs_delete_inode,
25 };
26 
27 struct sysfs_dirent sysfs_root = {
28 	.s_count	= ATOMIC_INIT(1),
29 	.s_flags	= SYSFS_ROOT,
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 	inode->i_op = &sysfs_dir_inode_operations;
54 	inode->i_fop = &sysfs_dir_operations;
55 	inc_nlink(inode); /* directory, account for "." */
56 	unlock_new_inode(inode);
57 
58 	/* instantiate and link root dentry */
59 	root = d_alloc_root(inode);
60 	if (!root) {
61 		pr_debug("%s: could not get root dentry!\n",__FUNCTION__);
62 		iput(inode);
63 		return -ENOMEM;
64 	}
65 	sysfs_root.s_dentry = root;
66 	root->d_fsdata = &sysfs_root;
67 	sb->s_root = root;
68 	return 0;
69 }
70 
71 static int sysfs_get_sb(struct file_system_type *fs_type,
72 	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
73 {
74 	return get_sb_single(fs_type, flags, data, sysfs_fill_super, mnt);
75 }
76 
77 static struct file_system_type sysfs_fs_type = {
78 	.name		= "sysfs",
79 	.get_sb		= sysfs_get_sb,
80 	.kill_sb	= kill_litter_super,
81 };
82 
83 int __init sysfs_init(void)
84 {
85 	int err = -ENOMEM;
86 
87 	sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache",
88 					      sizeof(struct sysfs_dirent),
89 					      0, 0, NULL);
90 	if (!sysfs_dir_cachep)
91 		goto out;
92 
93 	err = register_filesystem(&sysfs_fs_type);
94 	if (!err) {
95 		sysfs_mount = kern_mount(&sysfs_fs_type);
96 		if (IS_ERR(sysfs_mount)) {
97 			printk(KERN_ERR "sysfs: could not mount!\n");
98 			err = PTR_ERR(sysfs_mount);
99 			sysfs_mount = NULL;
100 			unregister_filesystem(&sysfs_fs_type);
101 			goto out_err;
102 		}
103 	} else
104 		goto out_err;
105 out:
106 	return err;
107 out_err:
108 	kmem_cache_destroy(sysfs_dir_cachep);
109 	sysfs_dir_cachep = NULL;
110 	goto out;
111 }
112