1 /*
2 * JFFS2 -- Journalling Flash File System, Version 2.
3 *
4 * Copyright © 2001-2007 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 *
10 */
11
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13
14 #include <linux/kernel.h>
15 #include <linux/fs.h>
16 #include <linux/namei.h>
17 #include "nodelist.h"
18
19 static void *jffs2_follow_link(struct dentry *dentry, struct nameidata *nd);
20
21 const struct inode_operations jffs2_symlink_inode_operations =
22 {
23 .readlink = generic_readlink,
24 .follow_link = jffs2_follow_link,
25 .get_acl = jffs2_get_acl,
26 .setattr = jffs2_setattr,
27 .setxattr = jffs2_setxattr,
28 .getxattr = jffs2_getxattr,
29 .listxattr = jffs2_listxattr,
30 .removexattr = jffs2_removexattr
31 };
32
jffs2_follow_link(struct dentry * dentry,struct nameidata * nd)33 static void *jffs2_follow_link(struct dentry *dentry, struct nameidata *nd)
34 {
35 struct jffs2_inode_info *f = JFFS2_INODE_INFO(dentry->d_inode);
36 char *p = (char *)f->target;
37
38 /*
39 * We don't acquire the f->sem mutex here since the only data we
40 * use is f->target.
41 *
42 * 1. If we are here the inode has already built and f->target has
43 * to point to the target path.
44 * 2. Nobody uses f->target (if the inode is symlink's inode). The
45 * exception is inode freeing function which frees f->target. But
46 * it can't be called while we are here and before VFS has
47 * stopped using our f->target string which we provide by means of
48 * nd_set_link() call.
49 */
50
51 if (!p) {
52 pr_err("%s(): can't find symlink target\n", __func__);
53 p = ERR_PTR(-EIO);
54 }
55 jffs2_dbg(1, "%s(): target path is '%s'\n",
56 __func__, (char *)f->target);
57
58 nd_set_link(nd, p);
59
60 /*
61 * We will unlock the f->sem mutex but VFS will use the f->target string. This is safe
62 * since the only way that may cause f->target to be changed is iput() operation.
63 * But VFS will not use f->target after iput() has been called.
64 */
65 return NULL;
66 }
67
68