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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> | |
16 | #include <linux/pagemap.h> | |
17 | #include <linux/init.h> | |
5a0e3ad6 | 18 | #include <linux/slab.h> |
7063fbf2 JB |
19 | |
20 | #include <linux/configfs.h> | |
21 | #include "configfs_internal.h" | |
22 | ||
23 | /* Random magic number */ | |
24 | #define CONFIGFS_MAGIC 0x62656570 | |
25 | ||
2a152ad3 | 26 | static struct vfsmount *configfs_mount = NULL; |
e18b890b | 27 | struct kmem_cache *configfs_dir_cachep; |
7063fbf2 JB |
28 | static int configfs_mnt_count = 0; |
29 | ||
ee9b6d61 | 30 | static const struct super_operations configfs_ops = { |
7063fbf2 JB |
31 | .statfs = simple_statfs, |
32 | .drop_inode = generic_delete_inode, | |
33 | }; | |
34 | ||
35 | static struct config_group configfs_root_group = { | |
36 | .cg_item = { | |
37 | .ci_namebuf = "root", | |
38 | .ci_name = configfs_root_group.cg_item.ci_namebuf, | |
39 | }, | |
40 | }; | |
41 | ||
42 | int configfs_is_root(struct config_item *item) | |
43 | { | |
44 | return item == &configfs_root_group.cg_item; | |
45 | } | |
46 | ||
47 | static struct configfs_dirent configfs_root = { | |
48 | .s_sibling = LIST_HEAD_INIT(configfs_root.s_sibling), | |
49 | .s_children = LIST_HEAD_INIT(configfs_root.s_children), | |
50 | .s_element = &configfs_root_group.cg_item, | |
51 | .s_type = CONFIGFS_ROOT, | |
3d0f89bb | 52 | .s_iattr = NULL, |
7063fbf2 JB |
53 | }; |
54 | ||
55 | static int configfs_fill_super(struct super_block *sb, void *data, int silent) | |
56 | { | |
57 | struct inode *inode; | |
58 | struct dentry *root; | |
59 | ||
09cbfeaf KS |
60 | sb->s_blocksize = PAGE_SIZE; |
61 | sb->s_blocksize_bits = PAGE_SHIFT; | |
7063fbf2 JB |
62 | sb->s_magic = CONFIGFS_MAGIC; |
63 | sb->s_op = &configfs_ops; | |
3d0f89bb | 64 | sb->s_time_gran = 1; |
7063fbf2 | 65 | |
3d0f89bb | 66 | inode = configfs_new_inode(S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO, |
b7c177fc | 67 | &configfs_root, sb); |
7063fbf2 | 68 | if (inode) { |
81d44ed1 | 69 | inode->i_op = &configfs_root_inode_operations; |
7063fbf2 JB |
70 | inode->i_fop = &configfs_dir_operations; |
71 | /* directory inodes start off with i_nlink == 2 (for "." entry) */ | |
d8c76e6f | 72 | inc_nlink(inode); |
7063fbf2 | 73 | } else { |
1d88aa44 | 74 | pr_debug("could not get root inode\n"); |
7063fbf2 JB |
75 | return -ENOMEM; |
76 | } | |
77 | ||
48fde701 | 78 | root = d_make_root(inode); |
7063fbf2 | 79 | if (!root) { |
8e24eea7 | 80 | pr_debug("%s: could not get root dentry!\n",__func__); |
7063fbf2 JB |
81 | return -ENOMEM; |
82 | } | |
83 | config_group_init(&configfs_root_group); | |
84 | configfs_root_group.cg_item.ci_dentry = root; | |
85 | root->d_fsdata = &configfs_root; | |
86 | sb->s_root = root; | |
d463a0c4 | 87 | sb->s_d_op = &configfs_dentry_ops; /* the rest get that */ |
7063fbf2 JB |
88 | return 0; |
89 | } | |
90 | ||
fc14f2fe AV |
91 | static struct dentry *configfs_do_mount(struct file_system_type *fs_type, |
92 | int flags, const char *dev_name, void *data) | |
7063fbf2 | 93 | { |
fc14f2fe | 94 | return mount_single(fs_type, flags, data, configfs_fill_super); |
7063fbf2 JB |
95 | } |
96 | ||
97 | static struct file_system_type configfs_fs_type = { | |
98 | .owner = THIS_MODULE, | |
99 | .name = "configfs", | |
fc14f2fe | 100 | .mount = configfs_do_mount, |
7063fbf2 JB |
101 | .kill_sb = kill_litter_super, |
102 | }; | |
7f78e035 | 103 | MODULE_ALIAS_FS("configfs"); |
7063fbf2 | 104 | |
2a152ad3 | 105 | struct dentry *configfs_pin_fs(void) |
7063fbf2 | 106 | { |
2a152ad3 | 107 | int err = simple_pin_fs(&configfs_fs_type, &configfs_mount, |
7063fbf2 | 108 | &configfs_mnt_count); |
2a152ad3 | 109 | return err ? ERR_PTR(err) : configfs_mount->mnt_root; |
7063fbf2 JB |
110 | } |
111 | ||
112 | void configfs_release_fs(void) | |
113 | { | |
114 | simple_release_fs(&configfs_mount, &configfs_mnt_count); | |
115 | } | |
116 | ||
117 | ||
7063fbf2 JB |
118 | static int __init configfs_init(void) |
119 | { | |
3d0f89bb JB |
120 | int err = -ENOMEM; |
121 | ||
122 | configfs_dir_cachep = kmem_cache_create("configfs_dir_cache", | |
123 | sizeof(struct configfs_dirent), | |
20c2df83 | 124 | 0, 0, NULL); |
3d0f89bb JB |
125 | if (!configfs_dir_cachep) |
126 | goto out; | |
7063fbf2 | 127 | |
f9bb4882 EB |
128 | err = sysfs_create_mount_point(kernel_kobj, "config"); |
129 | if (err) | |
7c6455e3 AV |
130 | goto out2; |
131 | ||
7063fbf2 | 132 | err = register_filesystem(&configfs_fs_type); |
7c6455e3 | 133 | if (err) |
b4caecd4 | 134 | goto out3; |
7063fbf2 | 135 | |
7c6455e3 | 136 | return 0; |
7c6455e3 | 137 | out3: |
b4caecd4 | 138 | pr_err("Unable to register filesystem!\n"); |
f9bb4882 | 139 | sysfs_remove_mount_point(kernel_kobj, "config"); |
7c6455e3 AV |
140 | out2: |
141 | kmem_cache_destroy(configfs_dir_cachep); | |
142 | configfs_dir_cachep = NULL; | |
3d0f89bb | 143 | out: |
7063fbf2 JB |
144 | return err; |
145 | } | |
146 | ||
147 | static void __exit configfs_exit(void) | |
148 | { | |
149 | unregister_filesystem(&configfs_fs_type); | |
f9bb4882 | 150 | sysfs_remove_mount_point(kernel_kobj, "config"); |
3d0f89bb JB |
151 | kmem_cache_destroy(configfs_dir_cachep); |
152 | configfs_dir_cachep = NULL; | |
7063fbf2 JB |
153 | } |
154 | ||
155 | MODULE_AUTHOR("Oracle"); | |
156 | MODULE_LICENSE("GPL"); | |
3d0f89bb | 157 | MODULE_VERSION("0.0.2"); |
7063fbf2 JB |
158 | MODULE_DESCRIPTION("Simple RAM filesystem for user driven kernel subsystem configuration."); |
159 | ||
f5b69770 | 160 | core_initcall(configfs_init); |
7063fbf2 | 161 | module_exit(configfs_exit); |