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>
31 #include <linux/configfs.h>
32 #include "configfs_internal.h"
34 /* Protects attachments of new symlinks */
35 DEFINE_MUTEX(configfs_symlink_mutex);
37 static int item_depth(struct config_item * item)
39 struct config_item * p = item;
41 do { depth++; } while ((p = p->ci_parent) && !configfs_is_root(p));
45 static int item_path_length(struct config_item * item)
47 struct config_item * p = item;
50 length += strlen(config_item_name(p)) + 1;
52 } while (p && !configfs_is_root(p));
56 static void fill_item_path(struct config_item * item, char * buffer, int length)
58 struct config_item * p;
61 for (p = item; p && !configfs_is_root(p); p = p->ci_parent) {
62 int cur = strlen(config_item_name(p));
64 /* back up enough to print this bus id with '/' */
66 strncpy(buffer + length,config_item_name(p),cur);
67 *(buffer + --length) = '/';
71 static int create_link(struct config_item *parent_item,
72 struct config_item *item,
73 struct dentry *dentry)
75 struct configfs_dirent *target_sd = item->ci_dentry->d_fsdata;
76 struct configfs_symlink *sl;
80 sl = kmalloc(sizeof(struct configfs_symlink), GFP_KERNEL);
82 sl->sl_target = config_item_get(item);
83 spin_lock(&configfs_dirent_lock);
84 if (target_sd->s_type & CONFIGFS_USET_DROPPING) {
85 spin_unlock(&configfs_dirent_lock);
86 config_item_put(item);
90 list_add(&sl->sl_list, &target_sd->s_links);
91 spin_unlock(&configfs_dirent_lock);
92 ret = configfs_create_link(sl, parent_item->ci_dentry,
95 spin_lock(&configfs_dirent_lock);
96 list_del_init(&sl->sl_list);
97 spin_unlock(&configfs_dirent_lock);
98 config_item_put(item);
107 static int get_target(const char *symname, struct nameidata *nd,
108 struct config_item **target)
112 ret = path_lookup(symname, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, nd);
114 if (nd->path.dentry->d_sb == configfs_sb) {
115 *target = configfs_get_config_item(nd->path.dentry);
128 int configfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
132 struct config_item *parent_item;
133 struct config_item *target_item;
134 struct config_item_type *type;
136 ret = -EPERM; /* What lack-of-symlink returns */
137 if (dentry->d_parent == configfs_sb->s_root)
140 parent_item = configfs_get_config_item(dentry->d_parent);
141 type = parent_item->ci_type;
143 if (!type || !type->ct_item_ops ||
144 !type->ct_item_ops->allow_link)
147 ret = get_target(symname, &nd, &target_item);
151 ret = type->ct_item_ops->allow_link(parent_item, target_item);
153 mutex_lock(&configfs_symlink_mutex);
154 ret = create_link(parent_item, target_item, dentry);
155 mutex_unlock(&configfs_symlink_mutex);
156 if (ret && type->ct_item_ops->drop_link)
157 type->ct_item_ops->drop_link(parent_item,
161 config_item_put(target_item);
165 config_item_put(parent_item);
171 int configfs_unlink(struct inode *dir, struct dentry *dentry)
173 struct configfs_dirent *sd = dentry->d_fsdata;
174 struct configfs_symlink *sl;
175 struct config_item *parent_item;
176 struct config_item_type *type;
179 ret = -EPERM; /* What lack-of-symlink returns */
180 if (!(sd->s_type & CONFIGFS_ITEM_LINK))
183 BUG_ON(dentry->d_parent == configfs_sb->s_root);
187 parent_item = configfs_get_config_item(dentry->d_parent);
188 type = parent_item->ci_type;
190 spin_lock(&configfs_dirent_lock);
191 list_del_init(&sd->s_sibling);
192 spin_unlock(&configfs_dirent_lock);
193 configfs_drop_dentry(sd, dentry->d_parent);
198 * drop_link() must be called before
199 * list_del_init(&sl->sl_list), so that the order of
200 * drop_link(this, target) and drop_item(target) is preserved.
202 if (type && type->ct_item_ops &&
203 type->ct_item_ops->drop_link)
204 type->ct_item_ops->drop_link(parent_item,
207 spin_lock(&configfs_dirent_lock);
208 list_del_init(&sl->sl_list);
209 spin_unlock(&configfs_dirent_lock);
211 /* Put reference from create_link() */
212 config_item_put(sl->sl_target);
215 config_item_put(parent_item);
223 static int configfs_get_target_path(struct config_item * item, struct config_item * target,
229 depth = item_depth(item);
230 size = item_path_length(target) + depth * 3 - 1;
232 return -ENAMETOOLONG;
234 pr_debug("%s: depth = %d, size = %d\n", __func__, depth, size);
236 for (s = path; depth--; s += 3)
239 fill_item_path(target, path, size);
240 pr_debug("%s: path = '%s'\n", __func__, path);
245 static int configfs_getlink(struct dentry *dentry, char * path)
247 struct config_item *item, *target_item;
250 item = configfs_get_config_item(dentry->d_parent);
254 target_item = configfs_get_config_item(dentry);
256 config_item_put(item);
260 down_read(&configfs_rename_sem);
261 error = configfs_get_target_path(item, target_item, path);
262 up_read(&configfs_rename_sem);
264 config_item_put(item);
265 config_item_put(target_item);
270 static void *configfs_follow_link(struct dentry *dentry, struct nameidata *nd)
273 unsigned long page = get_zeroed_page(GFP_KERNEL);
276 error = configfs_getlink(dentry, (char *)page);
278 nd_set_link(nd, (char *)page);
283 nd_set_link(nd, ERR_PTR(error));
287 static void configfs_put_link(struct dentry *dentry, struct nameidata *nd,
291 unsigned long page = (unsigned long)cookie;
296 const struct inode_operations configfs_symlink_inode_operations = {
297 .follow_link = configfs_follow_link,
298 .readlink = generic_readlink,
299 .put_link = configfs_put_link,
300 .setattr = configfs_setattr,