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 .setattr = jffs2_setattr, 26 .setxattr = jffs2_setxattr, 27 .getxattr = jffs2_getxattr, 28 .listxattr = jffs2_listxattr, 29 .removexattr = jffs2_removexattr 30 }; 31 32 static void *jffs2_follow_link(struct dentry *dentry, struct nameidata *nd) 33 { 34 struct jffs2_inode_info *f = JFFS2_INODE_INFO(d_inode(dentry)); 35 char *p = (char *)f->target; 36 37 /* 38 * We don't acquire the f->sem mutex here since the only data we 39 * use is f->target. 40 * 41 * 1. If we are here the inode has already built and f->target has 42 * to point to the target path. 43 * 2. Nobody uses f->target (if the inode is symlink's inode). The 44 * exception is inode freeing function which frees f->target. But 45 * it can't be called while we are here and before VFS has 46 * stopped using our f->target string which we provide by means of 47 * nd_set_link() call. 48 */ 49 50 if (!p) { 51 pr_err("%s(): can't find symlink target\n", __func__); 52 p = ERR_PTR(-EIO); 53 } 54 jffs2_dbg(1, "%s(): target path is '%s'\n", 55 __func__, (char *)f->target); 56 57 nd_set_link(nd, p); 58 59 /* 60 * We will unlock the f->sem mutex but VFS will use the f->target string. This is safe 61 * since the only way that may cause f->target to be changed is iput() operation. 62 * But VFS will not use f->target after iput() has been called. 63 */ 64 return NULL; 65 } 66 67