1 /* -*- mode: c; c-basic-offset: 8; -*-
2 * vim: noexpandtab sw=8 ts=8 sts=0:
4 * symlink.c - operations for configfs symlinks.
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.
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.
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.
22 * sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
24 * configfs Copyright (C) 2005 Oracle. All rights reserved.
28 #include <linux/module.h>
29 #include <linux/namei.h>
30 #include <linux/slab.h>
32 #include <linux/configfs.h>
33 #include "configfs_internal.h"
35 /* Protects attachments of new symlinks */
36 DEFINE_MUTEX(configfs_symlink_mutex);
38 static int item_depth(struct config_item * item)
40 struct config_item * p = item;
42 do { depth++; } while ((p = p->ci_parent) && !configfs_is_root(p));
46 static int item_path_length(struct config_item * item)
48 struct config_item * p = item;
51 length += strlen(config_item_name(p)) + 1;
53 } while (p && !configfs_is_root(p));
57 static void fill_item_path(struct config_item * item, char * buffer, int length)
59 struct config_item * p;
62 for (p = item; p && !configfs_is_root(p); p = p->ci_parent) {
63 int cur = strlen(config_item_name(p));
65 /* back up enough to print this bus id with '/' */
67 memcpy(buffer + length, config_item_name(p), cur);
68 *(buffer + --length) = '/';
72 static int create_link(struct config_item *parent_item,
73 struct config_item *item,
74 struct dentry *dentry)
76 struct configfs_dirent *target_sd = item->ci_dentry->d_fsdata;
77 struct configfs_symlink *sl;
81 if (!configfs_dirent_is_ready(target_sd))
84 sl = kmalloc(sizeof(struct configfs_symlink), GFP_KERNEL);
86 spin_lock(&configfs_dirent_lock);
87 if (target_sd->s_type & CONFIGFS_USET_DROPPING) {
88 spin_unlock(&configfs_dirent_lock);
92 sl->sl_target = config_item_get(item);
93 list_add(&sl->sl_list, &target_sd->s_links);
94 spin_unlock(&configfs_dirent_lock);
95 ret = configfs_create_link(sl, parent_item->ci_dentry,
98 spin_lock(&configfs_dirent_lock);
99 list_del_init(&sl->sl_list);
100 spin_unlock(&configfs_dirent_lock);
101 config_item_put(item);
111 static int get_target(const char *symname, struct path *path,
112 struct config_item **target, struct super_block *sb)
116 ret = kern_path(symname, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, path);
118 if (path->dentry->d_sb == sb) {
119 *target = configfs_get_config_item(path->dentry);
134 int configfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
138 struct configfs_dirent *sd;
139 struct config_item *parent_item;
140 struct config_item *target_item = NULL;
141 const struct config_item_type *type;
143 sd = dentry->d_parent->d_fsdata;
145 * Fake invisibility if dir belongs to a group/default groups hierarchy
149 if (!configfs_dirent_is_ready(sd))
152 parent_item = configfs_get_config_item(dentry->d_parent);
153 type = parent_item->ci_type;
156 if (!type || !type->ct_item_ops ||
157 !type->ct_item_ops->allow_link)
160 ret = get_target(symname, &path, &target_item, dentry->d_sb);
164 ret = type->ct_item_ops->allow_link(parent_item, target_item);
166 mutex_lock(&configfs_symlink_mutex);
167 ret = create_link(parent_item, target_item, dentry);
168 mutex_unlock(&configfs_symlink_mutex);
169 if (ret && type->ct_item_ops->drop_link)
170 type->ct_item_ops->drop_link(parent_item,
174 config_item_put(target_item);
178 config_item_put(parent_item);
184 int configfs_unlink(struct inode *dir, struct dentry *dentry)
186 struct configfs_dirent *sd = dentry->d_fsdata;
187 struct configfs_symlink *sl;
188 struct config_item *parent_item;
189 const struct config_item_type *type;
192 ret = -EPERM; /* What lack-of-symlink returns */
193 if (!(sd->s_type & CONFIGFS_ITEM_LINK))
198 parent_item = configfs_get_config_item(dentry->d_parent);
199 type = parent_item->ci_type;
201 spin_lock(&configfs_dirent_lock);
202 list_del_init(&sd->s_sibling);
203 spin_unlock(&configfs_dirent_lock);
204 configfs_drop_dentry(sd, dentry->d_parent);
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.
213 if (type && type->ct_item_ops &&
214 type->ct_item_ops->drop_link)
215 type->ct_item_ops->drop_link(parent_item,
218 spin_lock(&configfs_dirent_lock);
219 list_del_init(&sl->sl_list);
220 spin_unlock(&configfs_dirent_lock);
222 /* Put reference from create_link() */
223 config_item_put(sl->sl_target);
226 config_item_put(parent_item);
234 static int configfs_get_target_path(struct config_item * item, struct config_item * target,
240 depth = item_depth(item);
241 size = item_path_length(target) + depth * 3 - 1;
243 return -ENAMETOOLONG;
245 pr_debug("%s: depth = %d, size = %d\n", __func__, depth, size);
247 for (s = path; depth--; s += 3)
250 fill_item_path(target, path, size);
251 pr_debug("%s: path = '%s'\n", __func__, path);
256 static int configfs_getlink(struct dentry *dentry, char * path)
258 struct config_item *item, *target_item;
261 item = configfs_get_config_item(dentry->d_parent);
265 target_item = configfs_get_config_item(dentry);
267 config_item_put(item);
271 down_read(&configfs_rename_sem);
272 error = configfs_get_target_path(item, target_item, path);
273 up_read(&configfs_rename_sem);
275 config_item_put(item);
276 config_item_put(target_item);
281 static const char *configfs_get_link(struct dentry *dentry,
283 struct delayed_call *done)
289 return ERR_PTR(-ECHILD);
291 body = kzalloc(PAGE_SIZE, GFP_KERNEL);
293 return ERR_PTR(-ENOMEM);
295 error = configfs_getlink(dentry, body);
297 set_delayed_call(done, kfree_link, body);
302 return ERR_PTR(error);
305 const struct inode_operations configfs_symlink_inode_operations = {
306 .get_link = configfs_get_link,
307 .setattr = configfs_setattr,