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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * JFFS2 -- Journalling Flash File System, Version 2.
3 *
David Woodhousec00c3102007-04-25 14:16:47 +01004 * Copyright © 2001-2007 Red Hat, Inc.
Linus Torvalds1da177e2005-04-16 15:20:36 -07005 *
6 * Created by David Woodhouse <dwmw2@infradead.org>
7 *
8 * For licensing information, see the file 'LICENCE' in this directory.
9 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070010 */
11
Linus Torvalds1da177e2005-04-16 15:20:36 -070012#include <linux/kernel.h>
13#include <linux/slab.h>
14#include <linux/fs.h>
15#include <linux/namei.h>
16#include "nodelist.h"
17
Al Viro008b1502005-08-20 00:17:39 +010018static void *jffs2_follow_link(struct dentry *dentry, struct nameidata *nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -070019
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -080020const struct inode_operations jffs2_symlink_inode_operations =
Thomas Gleixner182ec4e2005-11-07 11:16:07 +000021{
Linus Torvalds1da177e2005-04-16 15:20:36 -070022 .readlink = generic_readlink,
23 .follow_link = jffs2_follow_link,
Linus Torvalds18f4c642009-08-28 12:29:03 -070024 .check_acl = jffs2_check_acl,
KaiGai Koheiaa98d7c2006-05-13 15:09:47 +090025 .setattr = jffs2_setattr,
26 .setxattr = jffs2_setxattr,
27 .getxattr = jffs2_getxattr,
28 .listxattr = jffs2_listxattr,
29 .removexattr = jffs2_removexattr
Linus Torvalds1da177e2005-04-16 15:20:36 -070030};
31
Al Viro008b1502005-08-20 00:17:39 +010032static void *jffs2_follow_link(struct dentry *dentry, struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -070033{
Artem B. Bityuckiy32f1a952005-03-01 10:50:52 +000034 struct jffs2_inode_info *f = JFFS2_INODE_INFO(dentry->d_inode);
Artem B. Bityutskiy2b79adc2005-07-17 12:13:51 +010035 char *p = (char *)f->target;
36
Artem B. Bityuckiy32f1a952005-03-01 10:50:52 +000037 /*
38 * We don't acquire the f->sem mutex here since the only data we
Artem B. Bityutskiy2b79adc2005-07-17 12:13:51 +010039 * use is f->target.
Artem B. Bityuckiy32f1a952005-03-01 10:50:52 +000040 *
Artem B. Bityutskiy2b79adc2005-07-17 12:13:51 +010041 * 1. If we are here the inode has already built and f->target has
Artem B. Bityuckiy32f1a952005-03-01 10:50:52 +000042 * to point to the target path.
Artem B. Bityutskiy2b79adc2005-07-17 12:13:51 +010043 * 2. Nobody uses f->target (if the inode is symlink's inode). The
44 * exception is inode freeing function which frees f->target. But
Artem B. Bityuckiy32f1a952005-03-01 10:50:52 +000045 * it can't be called while we are here and before VFS has
Artem B. Bityutskiy2b79adc2005-07-17 12:13:51 +010046 * stopped using our f->target string which we provide by means of
Artem B. Bityuckiy32f1a952005-03-01 10:50:52 +000047 * nd_set_link() call.
48 */
Thomas Gleixner182ec4e2005-11-07 11:16:07 +000049
Al Viro2fb1e302005-08-19 22:42:16 +010050 if (!p) {
Qi Yongc7cf0c62006-10-16 19:42:23 +080051 printk(KERN_ERR "jffs2_follow_link(): can't find symlink target\n");
Al Viro2fb1e302005-08-19 22:42:16 +010052 p = ERR_PTR(-EIO);
Artem B. Bityuckiy32f1a952005-03-01 10:50:52 +000053 }
Artem B. Bityutskiy2b79adc2005-07-17 12:13:51 +010054 D1(printk(KERN_DEBUG "jffs2_follow_link(): target path is '%s'\n", (char *) f->target));
Artem B. Bityuckiy32f1a952005-03-01 10:50:52 +000055
Al Viro2fb1e302005-08-19 22:42:16 +010056 nd_set_link(nd, p);
Thomas Gleixner182ec4e2005-11-07 11:16:07 +000057
Artem B. Bityuckiy32f1a952005-03-01 10:50:52 +000058 /*
Artem B. Bityutskiy2b79adc2005-07-17 12:13:51 +010059 * We will unlock the f->sem mutex but VFS will use the f->target string. This is safe
60 * since the only way that may cause f->target to be changed is iput() operation.
61 * But VFS will not use f->target after iput() has been called.
Artem B. Bityuckiy32f1a952005-03-01 10:50:52 +000062 */
Al Viro008b1502005-08-20 00:17:39 +010063 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -070064}
65