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 static int item_depth(struct config_item * item)
36 struct config_item * p = item;
38 do { depth++; } while ((p = p->ci_parent) && !configfs_is_root(p));
42 static int item_path_length(struct config_item * item)
44 struct config_item * p = item;
47 length += strlen(config_item_name(p)) + 1;
49 } while (p && !configfs_is_root(p));
53 static void fill_item_path(struct config_item * item, char * buffer, int length)
55 struct config_item * p;
58 for (p = item; p && !configfs_is_root(p); p = p->ci_parent) {
59 int cur = strlen(config_item_name(p));
61 /* back up enough to print this bus id with '/' */
63 strncpy(buffer + length,config_item_name(p),cur);
64 *(buffer + --length) = '/';
68 static int create_link(struct config_item *parent_item,
69 struct config_item *item,
70 struct dentry *dentry)
72 struct configfs_dirent *target_sd = item->ci_dentry->d_fsdata;
73 struct configfs_symlink *sl;
77 sl = kmalloc(sizeof(struct configfs_symlink), GFP_KERNEL);
79 sl->sl_target = config_item_get(item);
80 spin_lock(&configfs_dirent_lock);
81 if (target_sd->s_type & CONFIGFS_USET_DROPPING) {
82 spin_unlock(&configfs_dirent_lock);
83 config_item_put(item);
87 list_add(&sl->sl_list, &target_sd->s_links);
88 spin_unlock(&configfs_dirent_lock);
89 ret = configfs_create_link(sl, parent_item->ci_dentry,
92 spin_lock(&configfs_dirent_lock);
93 list_del_init(&sl->sl_list);
94 spin_unlock(&configfs_dirent_lock);
95 config_item_put(item);
104 static int get_target(const char *symname, struct nameidata *nd,
105 struct config_item **target)
109 ret = path_lookup(symname, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, nd);
111 if (nd->path.dentry->d_sb == configfs_sb) {
112 *target = configfs_get_config_item(nd->path.dentry);
125 int configfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
129 struct config_item *parent_item;
130 struct config_item *target_item;
131 struct config_item_type *type;
133 ret = -EPERM; /* What lack-of-symlink returns */
134 if (dentry->d_parent == configfs_sb->s_root)
137 parent_item = configfs_get_config_item(dentry->d_parent);
138 type = parent_item->ci_type;
140 if (!type || !type->ct_item_ops ||
141 !type->ct_item_ops->allow_link)
144 ret = get_target(symname, &nd, &target_item);
148 ret = type->ct_item_ops->allow_link(parent_item, target_item);
150 ret = create_link(parent_item, target_item, dentry);
151 if (ret && type->ct_item_ops->drop_link)
152 type->ct_item_ops->drop_link(parent_item,
156 config_item_put(target_item);
160 config_item_put(parent_item);
166 int configfs_unlink(struct inode *dir, struct dentry *dentry)
168 struct configfs_dirent *sd = dentry->d_fsdata;
169 struct configfs_symlink *sl;
170 struct config_item *parent_item;
171 struct config_item_type *type;
174 ret = -EPERM; /* What lack-of-symlink returns */
175 if (!(sd->s_type & CONFIGFS_ITEM_LINK))
178 BUG_ON(dentry->d_parent == configfs_sb->s_root);
182 parent_item = configfs_get_config_item(dentry->d_parent);
183 type = parent_item->ci_type;
185 spin_lock(&configfs_dirent_lock);
186 list_del_init(&sd->s_sibling);
187 spin_unlock(&configfs_dirent_lock);
188 configfs_drop_dentry(sd, dentry->d_parent);
193 * drop_link() must be called before
194 * list_del_init(&sl->sl_list), so that the order of
195 * drop_link(this, target) and drop_item(target) is preserved.
197 if (type && type->ct_item_ops &&
198 type->ct_item_ops->drop_link)
199 type->ct_item_ops->drop_link(parent_item,
202 spin_lock(&configfs_dirent_lock);
203 list_del_init(&sl->sl_list);
204 spin_unlock(&configfs_dirent_lock);
206 /* Put reference from create_link() */
207 config_item_put(sl->sl_target);
210 config_item_put(parent_item);
218 static int configfs_get_target_path(struct config_item * item, struct config_item * target,
224 depth = item_depth(item);
225 size = item_path_length(target) + depth * 3 - 1;
227 return -ENAMETOOLONG;
229 pr_debug("%s: depth = %d, size = %d\n", __func__, depth, size);
231 for (s = path; depth--; s += 3)
234 fill_item_path(target, path, size);
235 pr_debug("%s: path = '%s'\n", __func__, path);
240 static int configfs_getlink(struct dentry *dentry, char * path)
242 struct config_item *item, *target_item;
245 item = configfs_get_config_item(dentry->d_parent);
249 target_item = configfs_get_config_item(dentry);
251 config_item_put(item);
255 down_read(&configfs_rename_sem);
256 error = configfs_get_target_path(item, target_item, path);
257 up_read(&configfs_rename_sem);
259 config_item_put(item);
260 config_item_put(target_item);
265 static void *configfs_follow_link(struct dentry *dentry, struct nameidata *nd)
268 unsigned long page = get_zeroed_page(GFP_KERNEL);
271 error = configfs_getlink(dentry, (char *)page);
273 nd_set_link(nd, (char *)page);
278 nd_set_link(nd, ERR_PTR(error));
282 static void configfs_put_link(struct dentry *dentry, struct nameidata *nd,
286 unsigned long page = (unsigned long)cookie;
291 const struct inode_operations configfs_symlink_inode_operations = {
292 .follow_link = configfs_follow_link,
293 .readlink = generic_readlink,
294 .put_link = configfs_put_link,
295 .setattr = configfs_setattr,