1/* -*- mode: c; c-basic-offset: 8; -*-
2 * vim: noexpandtab sw=8 ts=8 sts=0:
3 *
4 * mount.c - operations for initializing and mounting configfs.
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public
8 * License as published by the Free Software Foundation; either
9 * version 2 of the License, or (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14 * General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public
17 * License along with this program; if not, write to the
18 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
19 * Boston, MA 021110-1307, USA.
20 *
21 * Based on sysfs:
22 * 	sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
23 *
24 * configfs Copyright (C) 2005 Oracle.  All rights reserved.
25 */
26
27#include <linux/fs.h>
28#include <linux/module.h>
29#include <linux/mount.h>
30#include <linux/pagemap.h>
31#include <linux/init.h>
32#include <linux/slab.h>
33
34#include <linux/configfs.h>
35#include "configfs_internal.h"
36
37/* Random magic number */
38#define CONFIGFS_MAGIC 0x62656570
39
40static struct vfsmount *configfs_mount = NULL;
41struct kmem_cache *configfs_dir_cachep;
42static int configfs_mnt_count = 0;
43
44static const struct super_operations configfs_ops = {
45	.statfs		= simple_statfs,
46	.drop_inode	= generic_delete_inode,
47};
48
49static struct config_group configfs_root_group = {
50	.cg_item = {
51		.ci_namebuf	= "root",
52		.ci_name	= configfs_root_group.cg_item.ci_namebuf,
53	},
54};
55
56int configfs_is_root(struct config_item *item)
57{
58	return item == &configfs_root_group.cg_item;
59}
60
61static struct configfs_dirent configfs_root = {
62	.s_sibling	= LIST_HEAD_INIT(configfs_root.s_sibling),
63	.s_children	= LIST_HEAD_INIT(configfs_root.s_children),
64	.s_element	= &configfs_root_group.cg_item,
65	.s_type		= CONFIGFS_ROOT,
66	.s_iattr	= NULL,
67};
68
69static int configfs_fill_super(struct super_block *sb, void *data, int silent)
70{
71	struct inode *inode;
72	struct dentry *root;
73
74	sb->s_blocksize = PAGE_CACHE_SIZE;
75	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
76	sb->s_magic = CONFIGFS_MAGIC;
77	sb->s_op = &configfs_ops;
78	sb->s_time_gran = 1;
79
80	inode = configfs_new_inode(S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
81				   &configfs_root, sb);
82	if (inode) {
83		inode->i_op = &configfs_root_inode_operations;
84		inode->i_fop = &configfs_dir_operations;
85		/* directory inodes start off with i_nlink == 2 (for "." entry) */
86		inc_nlink(inode);
87	} else {
88		pr_debug("could not get root inode\n");
89		return -ENOMEM;
90	}
91
92	root = d_make_root(inode);
93	if (!root) {
94		pr_debug("%s: could not get root dentry!\n",__func__);
95		return -ENOMEM;
96	}
97	config_group_init(&configfs_root_group);
98	configfs_root_group.cg_item.ci_dentry = root;
99	root->d_fsdata = &configfs_root;
100	sb->s_root = root;
101	sb->s_d_op = &configfs_dentry_ops; /* the rest get that */
102	return 0;
103}
104
105static struct dentry *configfs_do_mount(struct file_system_type *fs_type,
106	int flags, const char *dev_name, void *data)
107{
108	return mount_single(fs_type, flags, data, configfs_fill_super);
109}
110
111static struct file_system_type configfs_fs_type = {
112	.owner		= THIS_MODULE,
113	.name		= "configfs",
114	.mount		= configfs_do_mount,
115	.kill_sb	= kill_litter_super,
116};
117MODULE_ALIAS_FS("configfs");
118
119struct dentry *configfs_pin_fs(void)
120{
121	int err = simple_pin_fs(&configfs_fs_type, &configfs_mount,
122			     &configfs_mnt_count);
123	return err ? ERR_PTR(err) : configfs_mount->mnt_root;
124}
125
126void configfs_release_fs(void)
127{
128	simple_release_fs(&configfs_mount, &configfs_mnt_count);
129}
130
131
132static struct kobject *config_kobj;
133
134static int __init configfs_init(void)
135{
136	int err = -ENOMEM;
137
138	configfs_dir_cachep = kmem_cache_create("configfs_dir_cache",
139						sizeof(struct configfs_dirent),
140						0, 0, NULL);
141	if (!configfs_dir_cachep)
142		goto out;
143
144	config_kobj = kobject_create_and_add("config", kernel_kobj);
145	if (!config_kobj)
146		goto out2;
147
148	err = configfs_inode_init();
149	if (err)
150		goto out3;
151
152	err = register_filesystem(&configfs_fs_type);
153	if (err)
154		goto out4;
155
156	return 0;
157out4:
158	pr_err("Unable to register filesystem!\n");
159	configfs_inode_exit();
160out3:
161	kobject_put(config_kobj);
162out2:
163	kmem_cache_destroy(configfs_dir_cachep);
164	configfs_dir_cachep = NULL;
165out:
166	return err;
167}
168
169static void __exit configfs_exit(void)
170{
171	unregister_filesystem(&configfs_fs_type);
172	kobject_put(config_kobj);
173	kmem_cache_destroy(configfs_dir_cachep);
174	configfs_dir_cachep = NULL;
175	configfs_inode_exit();
176}
177
178MODULE_AUTHOR("Oracle");
179MODULE_LICENSE("GPL");
180MODULE_VERSION("0.0.2");
181MODULE_DESCRIPTION("Simple RAM filesystem for user driven kernel subsystem configuration.");
182
183module_init(configfs_init);
184module_exit(configfs_exit);
185