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 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