summaryrefslogtreecommitdiffstats
path: root/fs/configfs/mount.c
blob: 55438dd58189934e7498f88a461c4dc6f83d2ece (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
// SPDX-License-Identifier: GPL-2.0-or-later
/* -*- mode: c; c-basic-offset: 8; -*-
 * vim: noexpandtab sw=8 ts=8 sts=0:
 *
 * mount.c - operations for initializing and mounting configfs.
 *
 * Based on sysfs:
 * 	sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
 *
 * configfs Copyright (C) 2005 Oracle.  All rights reserved.
 */

#include <linux/fs.h>
#include <linux/module.h>
#include <linux/mount.h>
#include <linux/fs_context.h>
#include <linux/pagemap.h>
#include <linux/init.h>
#include <linux/slab.h>

#include <linux/configfs.h>
#include "configfs_internal.h"

/* Random magic number */
#define CONFIGFS_MAGIC 0x62656570

static struct vfsmount *configfs_mount = NULL;
struct kmem_cache *configfs_dir_cachep;
static int configfs_mnt_count = 0;

static const struct super_operations configfs_ops = {
	.statfs		= simple_statfs,
	.drop_inode	= generic_delete_inode,
};

static struct config_group configfs_root_group = {
	.cg_item = {
		.ci_namebuf	= "root",
		.ci_name	= configfs_root_group.cg_item.ci_namebuf,
	},
};

int configfs_is_root(struct config_item *item)
{
	return item == &configfs_root_group.cg_item;
}

static struct configfs_dirent configfs_root = {
	.s_sibling	= LIST_HEAD_INIT(configfs_root.s_sibling),
	.s_children	= LIST_HEAD_INIT(configfs_root.s_children),
	.s_element	= &configfs_root_group.cg_item,
	.s_type		= CONFIGFS_ROOT,
	.s_iattr	= NULL,
};

static int configfs_fill_super(struct super_block *sb, struct fs_context *fc)
{
	struct inode *inode;
	struct dentry *root;

	sb->s_blocksize = PAGE_SIZE;
	sb->s_blocksize_bits = PAGE_SHIFT;
	sb->s_magic = CONFIGFS_MAGIC;
	sb->s_op = &configfs_ops;
	sb->s_time_gran = 1;

	inode = configfs_new_inode(S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
				   &configfs_root, sb);
	if (inode) {
		inode->i_op = &configfs_root_inode_operations;
		inode->i_fop = &configfs_dir_operations;
		/* directory inodes start off with i_nlink == 2 (for "." entry) */
		inc_nlink(inode);
	} else {
		pr_debug("could not get root inode\n");
		return -ENOMEM;
	}

	root = d_make_root(inode);
	if (!root) {
		pr_debug("%s: could not get root dentry!\n",__func__);
		return -ENOMEM;
	}
	config_group_init(&configfs_root_group);
	configfs_root_group.cg_item.ci_dentry = root;
	root->d_fsdata = &configfs_root;
	sb->s_root = root;
	sb->s_d_op = &configfs_dentry_ops; /* the rest get that */
	return 0;
}

static int configfs_get_tree(struct fs_context *fc)
{
	return get_tree_single(fc, configfs_fill_super);
}

static const struct fs_context_operations configfs_context_ops = {
	.get_tree	= configfs_get_tree,
};

static int configfs_init_fs_context(struct fs_context *fc)
{
	fc->ops = &configfs_context_ops;
	return 0;
}

static struct file_system_type configfs_fs_type = {
	.owner		= THIS_MODULE,
	.name		= "configfs",
	.init_fs_context = configfs_init_fs_context,
	.kill_sb	= kill_litter_super,
};
MODULE_ALIAS_FS("configfs");

struct dentry *configfs_pin_fs(void)
{
	int err = simple_pin_fs(&configfs_fs_type, &configfs_mount,
			     &configfs_mnt_count);
	return err ? ERR_PTR(err) : configfs_mount->mnt_root;
}

void configfs_release_fs(void)
{
	simple_release_fs(&configfs_mount, &configfs_mnt_count);
}


static int __init configfs_init(void)
{
	int err = -ENOMEM;

	configfs_dir_cachep = kmem_cache_create("configfs_dir_cache",
						sizeof(struct configfs_dirent),
						0, 0, NULL);
	if (!configfs_dir_cachep)
		goto out;

	err = sysfs_create_mount_point(kernel_kobj, "config");
	if (err)
		goto out2;

	err = register_filesystem(&configfs_fs_type);
	if (err)
		goto out3;

	return 0;
out3:
	pr_err("Unable to register filesystem!\n");
	sysfs_remove_mount_point(kernel_kobj, "config");
out2:
	kmem_cache_destroy(configfs_dir_cachep);
	configfs_dir_cachep = NULL;
out:
	return err;
}

static void __exit configfs_exit(void)
{
	unregister_filesystem(&configfs_fs_type);
	sysfs_remove_mount_point(kernel_kobj, "config");
	kmem_cache_destroy(configfs_dir_cachep);
	configfs_dir_cachep = NULL;
}

MODULE_AUTHOR("Oracle");
MODULE_LICENSE("GPL");
MODULE_VERSION("0.0.2");
MODULE_DESCRIPTION("Simple RAM filesystem for user driven kernel subsystem configuration.");

core_initcall(configfs_init);
module_exit(configfs_exit);