1 /* 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 * 10 * $Id: symlink.c,v 1.19 2005/11/07 11:14:42 gleixner Exp $ 11 * 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 21 static void *jffs2_follow_link(struct dentry *dentry, struct nameidata *nd); 22 23 struct inode_operations jffs2_symlink_inode_operations = 24 { 25 .readlink = generic_readlink, 26 .follow_link = jffs2_follow_link, 27 .setattr = jffs2_setattr 28 }; 29 30 static void *jffs2_follow_link(struct dentry *dentry, struct nameidata *nd) 31 { 32 struct jffs2_inode_info *f = JFFS2_INODE_INFO(dentry->d_inode); 33 char *p = (char *)f->target; 34 35 /* 36 * We don't acquire the f->sem mutex here since the only data we 37 * use is f->target. 38 * 39 * 1. If we are here the inode has already built and f->target has 40 * to point to the target path. 41 * 2. Nobody uses f->target (if the inode is symlink's inode). The 42 * exception is inode freeing function which frees f->target. But 43 * it can't be called while we are here and before VFS has 44 * stopped using our f->target string which we provide by means of 45 * nd_set_link() call. 46 */ 47 48 if (!p) { 49 printk(KERN_ERR "jffs2_follow_link(): can't find symlink taerget\n"); 50 p = ERR_PTR(-EIO); 51 } 52 D1(printk(KERN_DEBUG "jffs2_follow_link(): target path is '%s'\n", (char *) f->target)); 53 54 nd_set_link(nd, p); 55 56 /* 57 * We will unlock the f->sem mutex but VFS will use the f->target string. This is safe 58 * since the only way that may cause f->target to be changed is iput() operation. 59 * But VFS will not use f->target after iput() has been called. 60 */ 61 return NULL; 62 } 63 64