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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * JFFS2 -- Journalling Flash File System, Version 2.
3 *
4 * Copyright (C) 2001, 2002 Red Hat, Inc.
5 *
6 * Created by David Woodhouse <dwmw2@infradead.org>
7 *
8 * For licensing information, see the file 'LICENCE' in this directory.
9 *
Thomas Gleixner182ec4e2005-11-07 11:16:07 +000010 * $Id: symlink.c,v 1.19 2005/11/07 11:14:42 gleixner Exp $
Linus Torvalds1da177e2005-04-16 15:20:36 -070011 *
12 */
13
14
15#include <linux/kernel.h>
16#include <linux/slab.h>
17#include <linux/fs.h>
18#include <linux/namei.h>
19#include "nodelist.h"
20
Al Viro008b1502005-08-20 00:17:39 +010021static void *jffs2_follow_link(struct dentry *dentry, struct nameidata *nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -070022
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -080023const struct inode_operations jffs2_symlink_inode_operations =
Thomas Gleixner182ec4e2005-11-07 11:16:07 +000024{
Linus Torvalds1da177e2005-04-16 15:20:36 -070025 .readlink = generic_readlink,
26 .follow_link = jffs2_follow_link,
KaiGai Koheiaa98d7c2006-05-13 15:09:47 +090027 .permission = jffs2_permission,
28 .setattr = jffs2_setattr,
29 .setxattr = jffs2_setxattr,
30 .getxattr = jffs2_getxattr,
31 .listxattr = jffs2_listxattr,
32 .removexattr = jffs2_removexattr
Linus Torvalds1da177e2005-04-16 15:20:36 -070033};
34
Al Viro008b1502005-08-20 00:17:39 +010035static void *jffs2_follow_link(struct dentry *dentry, struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -070036{
Artem B. Bityuckiy32f1a952005-03-01 10:50:52 +000037 struct jffs2_inode_info *f = JFFS2_INODE_INFO(dentry->d_inode);
Artem B. Bityutskiy2b79adc2005-07-17 12:13:51 +010038 char *p = (char *)f->target;
39
Artem B. Bityuckiy32f1a952005-03-01 10:50:52 +000040 /*
41 * We don't acquire the f->sem mutex here since the only data we
Artem B. Bityutskiy2b79adc2005-07-17 12:13:51 +010042 * use is f->target.
Artem B. Bityuckiy32f1a952005-03-01 10:50:52 +000043 *
Artem B. Bityutskiy2b79adc2005-07-17 12:13:51 +010044 * 1. If we are here the inode has already built and f->target has
Artem B. Bityuckiy32f1a952005-03-01 10:50:52 +000045 * to point to the target path.
Artem B. Bityutskiy2b79adc2005-07-17 12:13:51 +010046 * 2. Nobody uses f->target (if the inode is symlink's inode). The
47 * exception is inode freeing function which frees f->target. But
Artem B. Bityuckiy32f1a952005-03-01 10:50:52 +000048 * it can't be called while we are here and before VFS has
Artem B. Bityutskiy2b79adc2005-07-17 12:13:51 +010049 * stopped using our f->target string which we provide by means of
Artem B. Bityuckiy32f1a952005-03-01 10:50:52 +000050 * nd_set_link() call.
51 */
Thomas Gleixner182ec4e2005-11-07 11:16:07 +000052
Al Viro2fb1e302005-08-19 22:42:16 +010053 if (!p) {
Qi Yongc7cf0c62006-10-16 19:42:23 +080054 printk(KERN_ERR "jffs2_follow_link(): can't find symlink target\n");
Al Viro2fb1e302005-08-19 22:42:16 +010055 p = ERR_PTR(-EIO);
Artem B. Bityuckiy32f1a952005-03-01 10:50:52 +000056 }
Artem B. Bityutskiy2b79adc2005-07-17 12:13:51 +010057 D1(printk(KERN_DEBUG "jffs2_follow_link(): target path is '%s'\n", (char *) f->target));
Artem B. Bityuckiy32f1a952005-03-01 10:50:52 +000058
Al Viro2fb1e302005-08-19 22:42:16 +010059 nd_set_link(nd, p);
Thomas Gleixner182ec4e2005-11-07 11:16:07 +000060
Artem B. Bityuckiy32f1a952005-03-01 10:50:52 +000061 /*
Artem B. Bityutskiy2b79adc2005-07-17 12:13:51 +010062 * We will unlock the f->sem mutex but VFS will use the f->target string. This is safe
63 * since the only way that may cause f->target to be changed is iput() operation.
64 * But VFS will not use f->target after iput() has been called.
Artem B. Bityuckiy32f1a952005-03-01 10:50:52 +000065 */
Al Viro008b1502005-08-20 00:17:39 +010066 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -070067}
68