]>
Commit | Line | Data |
---|---|---|
7063fbf2 JB |
1 | /* -*- mode: c; c-basic-offset: 8; -*- |
2 | * vim: noexpandtab sw=8 ts=8 sts=0: | |
3 | * | |
4 | * symlink.c - operations for configfs symlinks. | |
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/namei.h> | |
5a0e3ad6 | 30 | #include <linux/slab.h> |
7063fbf2 JB |
31 | |
32 | #include <linux/configfs.h> | |
33 | #include "configfs_internal.h" | |
34 | ||
9a73d78c LR |
35 | /* Protects attachments of new symlinks */ |
36 | DEFINE_MUTEX(configfs_symlink_mutex); | |
37 | ||
7063fbf2 JB |
38 | static int item_depth(struct config_item * item) |
39 | { | |
40 | struct config_item * p = item; | |
41 | int depth = 0; | |
42 | do { depth++; } while ((p = p->ci_parent) && !configfs_is_root(p)); | |
43 | return depth; | |
44 | } | |
45 | ||
46 | static int item_path_length(struct config_item * item) | |
47 | { | |
48 | struct config_item * p = item; | |
49 | int length = 1; | |
50 | do { | |
51 | length += strlen(config_item_name(p)) + 1; | |
52 | p = p->ci_parent; | |
53 | } while (p && !configfs_is_root(p)); | |
54 | return length; | |
55 | } | |
56 | ||
57 | static void fill_item_path(struct config_item * item, char * buffer, int length) | |
58 | { | |
59 | struct config_item * p; | |
60 | ||
61 | --length; | |
62 | for (p = item; p && !configfs_is_root(p); p = p->ci_parent) { | |
63 | int cur = strlen(config_item_name(p)); | |
64 | ||
65 | /* back up enough to print this bus id with '/' */ | |
66 | length -= cur; | |
67 | strncpy(buffer + length,config_item_name(p),cur); | |
68 | *(buffer + --length) = '/'; | |
69 | } | |
70 | } | |
71 | ||
72 | static int create_link(struct config_item *parent_item, | |
e7515d06 | 73 | struct config_item *item, |
7063fbf2 JB |
74 | struct dentry *dentry) |
75 | { | |
76 | struct configfs_dirent *target_sd = item->ci_dentry->d_fsdata; | |
77 | struct configfs_symlink *sl; | |
78 | int ret; | |
79 | ||
2a109f2a LR |
80 | ret = -ENOENT; |
81 | if (!configfs_dirent_is_ready(target_sd)) | |
82 | goto out; | |
7063fbf2 JB |
83 | ret = -ENOMEM; |
84 | sl = kmalloc(sizeof(struct configfs_symlink), GFP_KERNEL); | |
85 | if (sl) { | |
5301a77d | 86 | spin_lock(&configfs_dirent_lock); |
4768e9b1 LR |
87 | if (target_sd->s_type & CONFIGFS_USET_DROPPING) { |
88 | spin_unlock(&configfs_dirent_lock); | |
4768e9b1 LR |
89 | kfree(sl); |
90 | return -ENOENT; | |
91 | } | |
ba80aa90 | 92 | sl->sl_target = config_item_get(item); |
7063fbf2 | 93 | list_add(&sl->sl_list, &target_sd->s_links); |
5301a77d | 94 | spin_unlock(&configfs_dirent_lock); |
7063fbf2 JB |
95 | ret = configfs_create_link(sl, parent_item->ci_dentry, |
96 | dentry); | |
97 | if (ret) { | |
5301a77d | 98 | spin_lock(&configfs_dirent_lock); |
7063fbf2 | 99 | list_del_init(&sl->sl_list); |
5301a77d | 100 | spin_unlock(&configfs_dirent_lock); |
7063fbf2 JB |
101 | config_item_put(item); |
102 | kfree(sl); | |
103 | } | |
104 | } | |
105 | ||
2a109f2a | 106 | out: |
7063fbf2 JB |
107 | return ret; |
108 | } | |
109 | ||
110 | ||
421748ec | 111 | static int get_target(const char *symname, struct path *path, |
b7c177fc | 112 | struct config_item **target, struct super_block *sb) |
7063fbf2 JB |
113 | { |
114 | int ret; | |
115 | ||
421748ec | 116 | ret = kern_path(symname, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, path); |
7063fbf2 | 117 | if (!ret) { |
b7c177fc | 118 | if (path->dentry->d_sb == sb) { |
421748ec | 119 | *target = configfs_get_config_item(path->dentry); |
7063fbf2 JB |
120 | if (!*target) { |
121 | ret = -ENOENT; | |
421748ec | 122 | path_put(path); |
7063fbf2 | 123 | } |
9b6e3102 | 124 | } else { |
7063fbf2 | 125 | ret = -EPERM; |
9b6e3102 AV |
126 | path_put(path); |
127 | } | |
7063fbf2 JB |
128 | } |
129 | ||
130 | return ret; | |
131 | } | |
132 | ||
133 | ||
134 | int configfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname) | |
135 | { | |
136 | int ret; | |
421748ec | 137 | struct path path; |
2a109f2a | 138 | struct configfs_dirent *sd; |
7063fbf2 | 139 | struct config_item *parent_item; |
3c48f23a | 140 | struct config_item *target_item = NULL; |
aa293583 | 141 | const struct config_item_type *type; |
7063fbf2 | 142 | |
2a109f2a LR |
143 | sd = dentry->d_parent->d_fsdata; |
144 | /* | |
145 | * Fake invisibility if dir belongs to a group/default groups hierarchy | |
146 | * being attached | |
147 | */ | |
148 | ret = -ENOENT; | |
149 | if (!configfs_dirent_is_ready(sd)) | |
150 | goto out; | |
151 | ||
7063fbf2 JB |
152 | parent_item = configfs_get_config_item(dentry->d_parent); |
153 | type = parent_item->ci_type; | |
154 | ||
2a109f2a | 155 | ret = -EPERM; |
7063fbf2 JB |
156 | if (!type || !type->ct_item_ops || |
157 | !type->ct_item_ops->allow_link) | |
158 | goto out_put; | |
159 | ||
b7c177fc | 160 | ret = get_target(symname, &path, &target_item, dentry->d_sb); |
7063fbf2 JB |
161 | if (ret) |
162 | goto out_put; | |
163 | ||
164 | ret = type->ct_item_ops->allow_link(parent_item, target_item); | |
e7520651 | 165 | if (!ret) { |
9a73d78c | 166 | mutex_lock(&configfs_symlink_mutex); |
7063fbf2 | 167 | ret = create_link(parent_item, target_item, dentry); |
9a73d78c | 168 | mutex_unlock(&configfs_symlink_mutex); |
e7520651 LR |
169 | if (ret && type->ct_item_ops->drop_link) |
170 | type->ct_item_ops->drop_link(parent_item, | |
171 | target_item); | |
172 | } | |
7063fbf2 JB |
173 | |
174 | config_item_put(target_item); | |
421748ec | 175 | path_put(&path); |
7063fbf2 JB |
176 | |
177 | out_put: | |
178 | config_item_put(parent_item); | |
179 | ||
180 | out: | |
181 | return ret; | |
182 | } | |
183 | ||
184 | int configfs_unlink(struct inode *dir, struct dentry *dentry) | |
185 | { | |
186 | struct configfs_dirent *sd = dentry->d_fsdata; | |
187 | struct configfs_symlink *sl; | |
188 | struct config_item *parent_item; | |
aa293583 | 189 | const struct config_item_type *type; |
7063fbf2 JB |
190 | int ret; |
191 | ||
192 | ret = -EPERM; /* What lack-of-symlink returns */ | |
193 | if (!(sd->s_type & CONFIGFS_ITEM_LINK)) | |
194 | goto out; | |
195 | ||
7063fbf2 JB |
196 | sl = sd->s_element; |
197 | ||
198 | parent_item = configfs_get_config_item(dentry->d_parent); | |
199 | type = parent_item->ci_type; | |
200 | ||
6f610764 | 201 | spin_lock(&configfs_dirent_lock); |
7063fbf2 | 202 | list_del_init(&sd->s_sibling); |
6f610764 | 203 | spin_unlock(&configfs_dirent_lock); |
7063fbf2 JB |
204 | configfs_drop_dentry(sd, dentry->d_parent); |
205 | dput(dentry); | |
206 | configfs_put(sd); | |
207 | ||
208 | /* | |
209 | * drop_link() must be called before | |
210 | * list_del_init(&sl->sl_list), so that the order of | |
211 | * drop_link(this, target) and drop_item(target) is preserved. | |
212 | */ | |
213 | if (type && type->ct_item_ops && | |
214 | type->ct_item_ops->drop_link) | |
215 | type->ct_item_ops->drop_link(parent_item, | |
216 | sl->sl_target); | |
217 | ||
5301a77d | 218 | spin_lock(&configfs_dirent_lock); |
7063fbf2 | 219 | list_del_init(&sl->sl_list); |
5301a77d | 220 | spin_unlock(&configfs_dirent_lock); |
7063fbf2 JB |
221 | |
222 | /* Put reference from create_link() */ | |
223 | config_item_put(sl->sl_target); | |
224 | kfree(sl); | |
225 | ||
226 | config_item_put(parent_item); | |
227 | ||
228 | ret = 0; | |
229 | ||
230 | out: | |
231 | return ret; | |
232 | } | |
233 | ||
234 | static int configfs_get_target_path(struct config_item * item, struct config_item * target, | |
235 | char *path) | |
236 | { | |
237 | char * s; | |
238 | int depth, size; | |
239 | ||
240 | depth = item_depth(item); | |
241 | size = item_path_length(target) + depth * 3 - 1; | |
242 | if (size > PATH_MAX) | |
243 | return -ENAMETOOLONG; | |
244 | ||
8e24eea7 | 245 | pr_debug("%s: depth = %d, size = %d\n", __func__, depth, size); |
7063fbf2 JB |
246 | |
247 | for (s = path; depth--; s += 3) | |
248 | strcpy(s,"../"); | |
249 | ||
250 | fill_item_path(target, path, size); | |
8e24eea7 | 251 | pr_debug("%s: path = '%s'\n", __func__, path); |
7063fbf2 JB |
252 | |
253 | return 0; | |
254 | } | |
255 | ||
256 | static int configfs_getlink(struct dentry *dentry, char * path) | |
257 | { | |
258 | struct config_item *item, *target_item; | |
259 | int error = 0; | |
260 | ||
261 | item = configfs_get_config_item(dentry->d_parent); | |
262 | if (!item) | |
263 | return -EINVAL; | |
264 | ||
265 | target_item = configfs_get_config_item(dentry); | |
266 | if (!target_item) { | |
267 | config_item_put(item); | |
268 | return -EINVAL; | |
269 | } | |
270 | ||
271 | down_read(&configfs_rename_sem); | |
272 | error = configfs_get_target_path(item, target_item, path); | |
273 | up_read(&configfs_rename_sem); | |
274 | ||
275 | config_item_put(item); | |
276 | config_item_put(target_item); | |
277 | return error; | |
278 | ||
279 | } | |
280 | ||
6b255391 | 281 | static const char *configfs_get_link(struct dentry *dentry, |
fceef393 AV |
282 | struct inode *inode, |
283 | struct delayed_call *done) | |
7063fbf2 | 284 | { |
fceef393 | 285 | char *body; |
680baacb | 286 | int error; |
7063fbf2 | 287 | |
6b255391 AV |
288 | if (!dentry) |
289 | return ERR_PTR(-ECHILD); | |
290 | ||
fceef393 AV |
291 | body = kzalloc(PAGE_SIZE, GFP_KERNEL); |
292 | if (!body) | |
680baacb AV |
293 | return ERR_PTR(-ENOMEM); |
294 | ||
fceef393 | 295 | error = configfs_getlink(dentry, body); |
680baacb | 296 | if (!error) { |
fceef393 AV |
297 | set_delayed_call(done, kfree_link, body); |
298 | return body; | |
7063fbf2 JB |
299 | } |
300 | ||
fceef393 | 301 | kfree(body); |
680baacb | 302 | return ERR_PTR(error); |
7063fbf2 JB |
303 | } |
304 | ||
754661f1 | 305 | const struct inode_operations configfs_symlink_inode_operations = { |
6b255391 | 306 | .get_link = configfs_get_link, |
3d0f89bb | 307 | .setattr = configfs_setattr, |
7063fbf2 JB |
308 | }; |
309 |