11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * JFFS2 -- Journalling Flash File System, Version 2. 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 2001, 2002 Red Hat, Inc. 51da177e4SLinus Torvalds * 61da177e4SLinus Torvalds * Created by David Woodhouse <dwmw2@infradead.org> 71da177e4SLinus Torvalds * 81da177e4SLinus Torvalds * For licensing information, see the file 'LICENCE' in this directory. 91da177e4SLinus Torvalds * 10182ec4eeSThomas Gleixner * $Id: symlink.c,v 1.19 2005/11/07 11:14:42 gleixner Exp $ 111da177e4SLinus Torvalds * 121da177e4SLinus Torvalds */ 131da177e4SLinus Torvalds 141da177e4SLinus Torvalds 151da177e4SLinus Torvalds #include <linux/kernel.h> 161da177e4SLinus Torvalds #include <linux/slab.h> 171da177e4SLinus Torvalds #include <linux/fs.h> 181da177e4SLinus Torvalds #include <linux/namei.h> 191da177e4SLinus Torvalds #include "nodelist.h" 201da177e4SLinus Torvalds 21008b150aSAl Viro static void *jffs2_follow_link(struct dentry *dentry, struct nameidata *nd); 221da177e4SLinus Torvalds 2392e1d5beSArjan van de Ven const struct inode_operations jffs2_symlink_inode_operations = 241da177e4SLinus Torvalds { 251da177e4SLinus Torvalds .readlink = generic_readlink, 261da177e4SLinus Torvalds .follow_link = jffs2_follow_link, 27aa98d7cfSKaiGai Kohei .permission = jffs2_permission, 28aa98d7cfSKaiGai Kohei .setattr = jffs2_setattr, 29aa98d7cfSKaiGai Kohei .setxattr = jffs2_setxattr, 30aa98d7cfSKaiGai Kohei .getxattr = jffs2_getxattr, 31aa98d7cfSKaiGai Kohei .listxattr = jffs2_listxattr, 32aa98d7cfSKaiGai Kohei .removexattr = jffs2_removexattr 331da177e4SLinus Torvalds }; 341da177e4SLinus Torvalds 35008b150aSAl Viro static void *jffs2_follow_link(struct dentry *dentry, struct nameidata *nd) 361da177e4SLinus Torvalds { 3732f1a95dSArtem B. Bityuckiy struct jffs2_inode_info *f = JFFS2_INODE_INFO(dentry->d_inode); 382b79adccSArtem B. Bityutskiy char *p = (char *)f->target; 3932f1a95dSArtem B. Bityuckiy 4032f1a95dSArtem B. Bityuckiy /* 4132f1a95dSArtem B. Bityuckiy * We don't acquire the f->sem mutex here since the only data we 422b79adccSArtem B. Bityutskiy * use is f->target. 4332f1a95dSArtem B. Bityuckiy * 442b79adccSArtem B. Bityutskiy * 1. If we are here the inode has already built and f->target has 4532f1a95dSArtem B. Bityuckiy * to point to the target path. 462b79adccSArtem B. Bityutskiy * 2. Nobody uses f->target (if the inode is symlink's inode). The 472b79adccSArtem B. Bityutskiy * exception is inode freeing function which frees f->target. But 4832f1a95dSArtem B. Bityuckiy * it can't be called while we are here and before VFS has 492b79adccSArtem B. Bityutskiy * stopped using our f->target string which we provide by means of 5032f1a95dSArtem B. Bityuckiy * nd_set_link() call. 5132f1a95dSArtem B. Bityuckiy */ 5232f1a95dSArtem B. Bityuckiy 532fb1e308SAl Viro if (!p) { 54c7cf0c68SQi Yong printk(KERN_ERR "jffs2_follow_link(): can't find symlink target\n"); 552fb1e308SAl Viro p = ERR_PTR(-EIO); 562fb1e308SAl Viro } 572b79adccSArtem B. Bityutskiy D1(printk(KERN_DEBUG "jffs2_follow_link(): target path is '%s'\n", (char *) f->target)); 5832f1a95dSArtem B. Bityuckiy 592fb1e308SAl Viro nd_set_link(nd, p); 6032f1a95dSArtem B. Bityuckiy 6132f1a95dSArtem B. Bityuckiy /* 622b79adccSArtem B. Bityutskiy * We will unlock the f->sem mutex but VFS will use the f->target string. This is safe 632b79adccSArtem B. Bityutskiy * since the only way that may cause f->target to be changed is iput() operation. 642b79adccSArtem B. Bityutskiy * But VFS will not use f->target after iput() has been called. 6532f1a95dSArtem B. Bityuckiy */ 66008b150aSAl Viro return NULL; 671da177e4SLinus Torvalds } 681da177e4SLinus Torvalds 69