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 .permission = jffs2_permission, 28 .setattr = jffs2_setattr, 29 .setxattr = jffs2_setxattr, 30 .getxattr = jffs2_getxattr, 31 .listxattr = jffs2_listxattr, 32 .removexattr = jffs2_removexattr 33 }; 34 35 static void *jffs2_follow_link(struct dentry *dentry, struct nameidata *nd) 36 { 37 struct jffs2_inode_info *f = JFFS2_INODE_INFO(dentry->d_inode); 38 char *p = (char *)f->target; 39 40 /* 41 * We don't acquire the f->sem mutex here since the only data we 42 * use is f->target. 43 * 44 * 1. If we are here the inode has already built and f->target has 45 * to point to the target path. 46 * 2. Nobody uses f->target (if the inode is symlink's inode). The 47 * exception is inode freeing function which frees f->target. But 48 * it can't be called while we are here and before VFS has 49 * stopped using our f->target string which we provide by means of 50 * nd_set_link() call. 51 */ 52 53 if (!p) { 54 printk(KERN_ERR "jffs2_follow_link(): can't find symlink target\n"); 55 p = ERR_PTR(-EIO); 56 } 57 D1(printk(KERN_DEBUG "jffs2_follow_link(): target path is '%s'\n", (char *) f->target)); 58 59 nd_set_link(nd, p); 60 61 /* 62 * 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. 65 */ 66 return NULL; 67 } 68 69