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
40 static struct vfsmount *configfs_mount = NULL;
41 struct kmem_cache *configfs_dir_cachep;
42 static int configfs_mnt_count = 0;
43
44 static const struct super_operations configfs_ops = {
45 .statfs = simple_statfs,
46 .drop_inode = generic_delete_inode,
47 };
48
49 static 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
56 int configfs_is_root(struct config_item *item)
57 {
58 return item == &configfs_root_group.cg_item;
59 }
60
61 static 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
69 static 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_SIZE;
75 sb->s_blocksize_bits = PAGE_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
105 static 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
111 static 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 };
117 MODULE_ALIAS_FS("configfs");
118
119 struct 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
126 void configfs_release_fs(void)
127 {
128 simple_release_fs(&configfs_mount, &configfs_mnt_count);
129 }
130
131
132 static int __init configfs_init(void)
133 {
134 int err = -ENOMEM;
135
136 configfs_dir_cachep = kmem_cache_create("configfs_dir_cache",
137 sizeof(struct configfs_dirent),
138 0, 0, NULL);
139 if (!configfs_dir_cachep)
140 goto out;
141
142 err = sysfs_create_mount_point(kernel_kobj, "config");
143 if (err)
144 goto out2;
145
146 err = register_filesystem(&configfs_fs_type);
147 if (err)
148 goto out3;
149
150 return 0;
151 out3:
152 pr_err("Unable to register filesystem!\n");
153 sysfs_remove_mount_point(kernel_kobj, "config");
154 out2:
155 kmem_cache_destroy(configfs_dir_cachep);
156 configfs_dir_cachep = NULL;
157 out:
158 return err;
159 }
160
161 static void __exit configfs_exit(void)
162 {
163 unregister_filesystem(&configfs_fs_type);
164 sysfs_remove_mount_point(kernel_kobj, "config");
165 kmem_cache_destroy(configfs_dir_cachep);
166 configfs_dir_cachep = NULL;
167 }
168
169 MODULE_AUTHOR("Oracle");
170 MODULE_LICENSE("GPL");
171 MODULE_VERSION("0.0.2");
172 MODULE_DESCRIPTION("Simple RAM filesystem for user driven kernel subsystem configuration.");
173
174 core_initcall(configfs_init);
175 module_exit(configfs_exit);
176
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