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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
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_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
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;
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 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;
151out3:
152 pr_err("Unable to register filesystem!\n");
153 sysfs_remove_mount_point(kernel_kobj, "config");
154out2:
155 kmem_cache_destroy(configfs_dir_cachep);
156 configfs_dir_cachep = NULL;
157out:
158 return err;
159}
160
161static 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
169MODULE_AUTHOR("Oracle");
170MODULE_LICENSE("GPL");
171MODULE_VERSION("0.0.2");
172MODULE_DESCRIPTION("Simple RAM filesystem for user driven kernel subsystem configuration.");
173
174core_initcall(configfs_init);
175module_exit(configfs_exit);
176
