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328970de | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
7063fbf2 JB |
2 | /* -*- mode: c; c-basic-offset: 8; -*- |
3 | * vim: noexpandtab sw=8 ts=8 sts=0: | |
4 | * | |
5 | * mount.c - operations for initializing and mounting configfs. | |
6 | * | |
7063fbf2 JB |
7 | * Based on sysfs: |
8 | * sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel | |
9 | * | |
10 | * configfs Copyright (C) 2005 Oracle. All rights reserved. | |
11 | */ | |
12 | ||
13 | #include <linux/fs.h> | |
14 | #include <linux/module.h> | |
15 | #include <linux/mount.h> | |
6bc62f20 | 16 | #include <linux/fs_context.h> |
7063fbf2 JB |
17 | #include <linux/pagemap.h> |
18 | #include <linux/init.h> | |
5a0e3ad6 | 19 | #include <linux/slab.h> |
7063fbf2 JB |
20 | |
21 | #include <linux/configfs.h> | |
22 | #include "configfs_internal.h" | |
23 | ||
24 | /* Random magic number */ | |
25 | #define CONFIGFS_MAGIC 0x62656570 | |
26 | ||
2a152ad3 | 27 | static struct vfsmount *configfs_mount = NULL; |
e18b890b | 28 | struct kmem_cache *configfs_dir_cachep; |
7063fbf2 JB |
29 | static int configfs_mnt_count = 0; |
30 | ||
e9c03af2 AV |
31 | |
32 | static void configfs_free_inode(struct inode *inode) | |
33 | { | |
34 | if (S_ISLNK(inode->i_mode)) | |
35 | kfree(inode->i_link); | |
36 | free_inode_nonrcu(inode); | |
37 | } | |
38 | ||
ee9b6d61 | 39 | static const struct super_operations configfs_ops = { |
7063fbf2 JB |
40 | .statfs = simple_statfs, |
41 | .drop_inode = generic_delete_inode, | |
e9c03af2 | 42 | .free_inode = configfs_free_inode, |
7063fbf2 JB |
43 | }; |
44 | ||
45 | static struct config_group configfs_root_group = { | |
46 | .cg_item = { | |
47 | .ci_namebuf = "root", | |
48 | .ci_name = configfs_root_group.cg_item.ci_namebuf, | |
49 | }, | |
50 | }; | |
51 | ||
52 | int configfs_is_root(struct config_item *item) | |
53 | { | |
54 | return item == &configfs_root_group.cg_item; | |
55 | } | |
56 | ||
57 | static struct configfs_dirent configfs_root = { | |
58 | .s_sibling = LIST_HEAD_INIT(configfs_root.s_sibling), | |
59 | .s_children = LIST_HEAD_INIT(configfs_root.s_children), | |
60 | .s_element = &configfs_root_group.cg_item, | |
61 | .s_type = CONFIGFS_ROOT, | |
3d0f89bb | 62 | .s_iattr = NULL, |
7063fbf2 JB |
63 | }; |
64 | ||
6bc62f20 | 65 | static int configfs_fill_super(struct super_block *sb, struct fs_context *fc) |
7063fbf2 JB |
66 | { |
67 | struct inode *inode; | |
68 | struct dentry *root; | |
69 | ||
09cbfeaf KS |
70 | sb->s_blocksize = PAGE_SIZE; |
71 | sb->s_blocksize_bits = PAGE_SHIFT; | |
7063fbf2 JB |
72 | sb->s_magic = CONFIGFS_MAGIC; |
73 | sb->s_op = &configfs_ops; | |
3d0f89bb | 74 | sb->s_time_gran = 1; |
7063fbf2 | 75 | |
3d0f89bb | 76 | inode = configfs_new_inode(S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO, |
b7c177fc | 77 | &configfs_root, sb); |
7063fbf2 | 78 | if (inode) { |
81d44ed1 | 79 | inode->i_op = &configfs_root_inode_operations; |
7063fbf2 JB |
80 | inode->i_fop = &configfs_dir_operations; |
81 | /* directory inodes start off with i_nlink == 2 (for "." entry) */ | |
d8c76e6f | 82 | inc_nlink(inode); |
7063fbf2 | 83 | } else { |
1d88aa44 | 84 | pr_debug("could not get root inode\n"); |
7063fbf2 JB |
85 | return -ENOMEM; |
86 | } | |
87 | ||
48fde701 | 88 | root = d_make_root(inode); |
7063fbf2 | 89 | if (!root) { |
8e24eea7 | 90 | pr_debug("%s: could not get root dentry!\n",__func__); |
7063fbf2 JB |
91 | return -ENOMEM; |
92 | } | |
93 | config_group_init(&configfs_root_group); | |
94 | configfs_root_group.cg_item.ci_dentry = root; | |
95 | root->d_fsdata = &configfs_root; | |
96 | sb->s_root = root; | |
d463a0c4 | 97 | sb->s_d_op = &configfs_dentry_ops; /* the rest get that */ |
7063fbf2 JB |
98 | return 0; |
99 | } | |
100 | ||
6bc62f20 | 101 | static int configfs_get_tree(struct fs_context *fc) |
7063fbf2 | 102 | { |
6bc62f20 DH |
103 | return get_tree_single(fc, configfs_fill_super); |
104 | } | |
105 | ||
106 | static const struct fs_context_operations configfs_context_ops = { | |
107 | .get_tree = configfs_get_tree, | |
108 | }; | |
109 | ||
110 | static int configfs_init_fs_context(struct fs_context *fc) | |
111 | { | |
112 | fc->ops = &configfs_context_ops; | |
113 | return 0; | |
7063fbf2 JB |
114 | } |
115 | ||
116 | static struct file_system_type configfs_fs_type = { | |
117 | .owner = THIS_MODULE, | |
118 | .name = "configfs", | |
6bc62f20 | 119 | .init_fs_context = configfs_init_fs_context, |
7063fbf2 JB |
120 | .kill_sb = kill_litter_super, |
121 | }; | |
7f78e035 | 122 | MODULE_ALIAS_FS("configfs"); |
7063fbf2 | 123 | |
2a152ad3 | 124 | struct dentry *configfs_pin_fs(void) |
7063fbf2 | 125 | { |
2a152ad3 | 126 | int err = simple_pin_fs(&configfs_fs_type, &configfs_mount, |
7063fbf2 | 127 | &configfs_mnt_count); |
2a152ad3 | 128 | return err ? ERR_PTR(err) : configfs_mount->mnt_root; |
7063fbf2 JB |
129 | } |
130 | ||
131 | void configfs_release_fs(void) | |
132 | { | |
133 | simple_release_fs(&configfs_mount, &configfs_mnt_count); | |
134 | } | |
135 | ||
136 | ||
7063fbf2 JB |
137 | static int __init configfs_init(void) |
138 | { | |
3d0f89bb JB |
139 | int err = -ENOMEM; |
140 | ||
141 | configfs_dir_cachep = kmem_cache_create("configfs_dir_cache", | |
142 | sizeof(struct configfs_dirent), | |
20c2df83 | 143 | 0, 0, NULL); |
3d0f89bb JB |
144 | if (!configfs_dir_cachep) |
145 | goto out; | |
7063fbf2 | 146 | |
f9bb4882 EB |
147 | err = sysfs_create_mount_point(kernel_kobj, "config"); |
148 | if (err) | |
7c6455e3 AV |
149 | goto out2; |
150 | ||
7063fbf2 | 151 | err = register_filesystem(&configfs_fs_type); |
7c6455e3 | 152 | if (err) |
b4caecd4 | 153 | goto out3; |
7063fbf2 | 154 | |
7c6455e3 | 155 | return 0; |
7c6455e3 | 156 | out3: |
b4caecd4 | 157 | pr_err("Unable to register filesystem!\n"); |
f9bb4882 | 158 | sysfs_remove_mount_point(kernel_kobj, "config"); |
7c6455e3 AV |
159 | out2: |
160 | kmem_cache_destroy(configfs_dir_cachep); | |
161 | configfs_dir_cachep = NULL; | |
3d0f89bb | 162 | out: |
7063fbf2 JB |
163 | return err; |
164 | } | |
165 | ||
166 | static void __exit configfs_exit(void) | |
167 | { | |
168 | unregister_filesystem(&configfs_fs_type); | |
f9bb4882 | 169 | sysfs_remove_mount_point(kernel_kobj, "config"); |
3d0f89bb JB |
170 | kmem_cache_destroy(configfs_dir_cachep); |
171 | configfs_dir_cachep = NULL; | |
7063fbf2 JB |
172 | } |
173 | ||
174 | MODULE_AUTHOR("Oracle"); | |
175 | MODULE_LICENSE("GPL"); | |
3d0f89bb | 176 | MODULE_VERSION("0.0.2"); |
7063fbf2 JB |
177 | MODULE_DESCRIPTION("Simple RAM filesystem for user driven kernel subsystem configuration."); |
178 | ||
f5b69770 | 179 | core_initcall(configfs_init); |
7063fbf2 | 180 | module_exit(configfs_exit); |