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Joel Becker7063fbf2005-12-15 14:29:43 -08001/* -*- 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>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090032#include <linux/slab.h>
Joel Becker7063fbf2005-12-15 14:29:43 -080033
34#include <linux/configfs.h>
35#include "configfs_internal.h"
36
37/* Random magic number */
38#define CONFIGFS_MAGIC 0x62656570
39
Al Viro2a152ad2012-03-17 16:53:29 -040040static struct vfsmount *configfs_mount = NULL;
Christoph Lametere18b8902006-12-06 20:33:20 -080041struct kmem_cache *configfs_dir_cachep;
Joel Becker7063fbf2005-12-15 14:29:43 -080042static int configfs_mnt_count = 0;
43
Josef 'Jeff' Sipekee9b6d62007-02-12 00:55:41 -080044static const struct super_operations configfs_ops = {
Joel Becker7063fbf2005-12-15 14:29:43 -080045 .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,
Joel Becker3d0f89b2006-01-25 13:31:07 -080066 .s_iattr = NULL,
Joel Becker7063fbf2005-12-15 14:29:43 -080067};
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;
Joel Becker3d0f89b2006-01-25 13:31:07 -080078 sb->s_time_gran = 1;
Joel Becker7063fbf2005-12-15 14:29:43 -080079
Joel Becker3d0f89b2006-01-25 13:31:07 -080080 inode = configfs_new_inode(S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
Al Virob7c177f2012-03-17 16:24:54 -040081 &configfs_root, sb);
Joel Becker7063fbf2005-12-15 14:29:43 -080082 if (inode) {
Al Viro81d44ed12012-03-17 16:13:25 -040083 inode->i_op = &configfs_root_inode_operations;
Joel Becker7063fbf2005-12-15 14:29:43 -080084 inode->i_fop = &configfs_dir_operations;
85 /* directory inodes start off with i_nlink == 2 (for "." entry) */
Dave Hansend8c76e62006-09-30 23:29:04 -070086 inc_nlink(inode);
Joel Becker7063fbf2005-12-15 14:29:43 -080087 } else {
Fabian Frederick1d88aa42014-06-04 16:05:59 -070088 pr_debug("could not get root inode\n");
Joel Becker7063fbf2005-12-15 14:29:43 -080089 return -ENOMEM;
90 }
91
Al Viro48fde702012-01-08 22:15:13 -050092 root = d_make_root(inode);
Joel Becker7063fbf2005-12-15 14:29:43 -080093 if (!root) {
Harvey Harrison8e24eea2008-04-30 00:55:09 -070094 pr_debug("%s: could not get root dentry!\n",__func__);
Joel Becker7063fbf2005-12-15 14:29:43 -080095 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;
Al Virod463a0c2011-01-12 16:41:05 -0500101 sb->s_d_op = &configfs_dentry_ops; /* the rest get that */
Joel Becker7063fbf2005-12-15 14:29:43 -0800102 return 0;
103}
104
Al Virofc14f2f2010-07-25 01:48:30 +0400105static struct dentry *configfs_do_mount(struct file_system_type *fs_type,
106 int flags, const char *dev_name, void *data)
Joel Becker7063fbf2005-12-15 14:29:43 -0800107{
Al Virofc14f2f2010-07-25 01:48:30 +0400108 return mount_single(fs_type, flags, data, configfs_fill_super);
Joel Becker7063fbf2005-12-15 14:29:43 -0800109}
110
111static struct file_system_type configfs_fs_type = {
112 .owner = THIS_MODULE,
113 .name = "configfs",
Al Virofc14f2f2010-07-25 01:48:30 +0400114 .mount = configfs_do_mount,
Joel Becker7063fbf2005-12-15 14:29:43 -0800115 .kill_sb = kill_litter_super,
116};
Eric W. Biederman7f78e032013-03-02 19:39:14 -0800117MODULE_ALIAS_FS("configfs");
Joel Becker7063fbf2005-12-15 14:29:43 -0800118
Al Viro2a152ad2012-03-17 16:53:29 -0400119struct dentry *configfs_pin_fs(void)
Joel Becker7063fbf2005-12-15 14:29:43 -0800120{
Al Viro2a152ad2012-03-17 16:53:29 -0400121 int err = simple_pin_fs(&configfs_fs_type, &configfs_mount,
Joel Becker7063fbf2005-12-15 14:29:43 -0800122 &configfs_mnt_count);
Al Viro2a152ad2012-03-17 16:53:29 -0400123 return err ? ERR_PTR(err) : configfs_mount->mnt_root;
Joel Becker7063fbf2005-12-15 14:29:43 -0800124}
125
126void configfs_release_fs(void)
127{
128 simple_release_fs(&configfs_mount, &configfs_mnt_count);
129}
130
131
Joel Becker7063fbf2005-12-15 14:29:43 -0800132static int __init configfs_init(void)
133{
Joel Becker3d0f89b2006-01-25 13:31:07 -0800134 int err = -ENOMEM;
135
136 configfs_dir_cachep = kmem_cache_create("configfs_dir_cache",
137 sizeof(struct configfs_dirent),
Paul Mundt20c2df82007-07-20 10:11:58 +0900138 0, 0, NULL);
Joel Becker3d0f89b2006-01-25 13:31:07 -0800139 if (!configfs_dir_cachep)
140 goto out;
Joel Becker7063fbf2005-12-15 14:29:43 -0800141
Eric W. Biedermanf9bb4882015-05-13 17:35:41 -0500142 err = sysfs_create_mount_point(kernel_kobj, "config");
143 if (err)
Al Viro7c6455e2011-12-13 12:32:42 -0500144 goto out2;
Joel Becker7063fbf2005-12-15 14:29:43 -0800145
Christoph Hellwigb4caecd2015-01-14 10:42:32 +0100146 err = register_filesystem(&configfs_fs_type);
Al Viro7c6455e2011-12-13 12:32:42 -0500147 if (err)
148 goto out3;
149
Al Viro7c6455e2011-12-13 12:32:42 -0500150 return 0;
Al Viro7c6455e2011-12-13 12:32:42 -0500151out3:
Christoph Hellwigb4caecd2015-01-14 10:42:32 +0100152 pr_err("Unable to register filesystem!\n");
Eric W. Biedermanf9bb4882015-05-13 17:35:41 -0500153 sysfs_remove_mount_point(kernel_kobj, "config");
Al Viro7c6455e2011-12-13 12:32:42 -0500154out2:
155 kmem_cache_destroy(configfs_dir_cachep);
156 configfs_dir_cachep = NULL;
Joel Becker3d0f89b2006-01-25 13:31:07 -0800157out:
Joel Becker7063fbf2005-12-15 14:29:43 -0800158 return err;
159}
160
161static void __exit configfs_exit(void)
162{
163 unregister_filesystem(&configfs_fs_type);
Eric W. Biedermanf9bb4882015-05-13 17:35:41 -0500164 sysfs_remove_mount_point(kernel_kobj, "config");
Joel Becker3d0f89b2006-01-25 13:31:07 -0800165 kmem_cache_destroy(configfs_dir_cachep);
166 configfs_dir_cachep = NULL;
Joel Becker7063fbf2005-12-15 14:29:43 -0800167}
168
169MODULE_AUTHOR("Oracle");
170MODULE_LICENSE("GPL");
Joel Becker3d0f89b2006-01-25 13:31:07 -0800171MODULE_VERSION("0.0.2");
Joel Becker7063fbf2005-12-15 14:29:43 -0800172MODULE_DESCRIPTION("Simple RAM filesystem for user driven kernel subsystem configuration.");
173
Daniel Balutaf5b69772015-05-05 16:23:54 -0700174core_initcall(configfs_init);
Joel Becker7063fbf2005-12-15 14:29:43 -0800175module_exit(configfs_exit);