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 #include <linux/kernel.h> 13 #include <linux/fs.h> 14 #include <linux/namei.h> 15 #include "nodelist.h" 16 17 static void *jffs2_follow_link(struct dentry *dentry, struct nameidata *nd); 18 19 const struct inode_operations jffs2_symlink_inode_operations = 20 { 21 .readlink = generic_readlink, 22 .follow_link = jffs2_follow_link, 23 .check_acl = jffs2_check_acl, 24 .setattr = jffs2_setattr, 25 .setxattr = jffs2_setxattr, 26 .getxattr = jffs2_getxattr, 27 .listxattr = jffs2_listxattr, 28 .removexattr = jffs2_removexattr 29 }; 30 31 static void *jffs2_follow_link(struct dentry *dentry, struct nameidata *nd) 32 { 33 struct jffs2_inode_info *f = JFFS2_INODE_INFO(dentry->d_inode); 34 char *p = (char *)f->target; 35 36 /* 37 * We don't acquire the f->sem mutex here since the only data we 38 * use is f->target. 39 * 40 * 1. If we are here the inode has already built and f->target has 41 * to point to the target path. 42 * 2. Nobody uses f->target (if the inode is symlink's inode). The 43 * exception is inode freeing function which frees f->target. But 44 * it can't be called while we are here and before VFS has 45 * stopped using our f->target string which we provide by means of 46 * nd_set_link() call. 47 */ 48 49 if (!p) { 50 printk(KERN_ERR "jffs2_follow_link(): can't find symlink target\n"); 51 p = ERR_PTR(-EIO); 52 } 53 D1(printk(KERN_DEBUG "jffs2_follow_link(): target path is '%s'\n", (char *) f->target)); 54 55 nd_set_link(nd, p); 56 57 /* 58 * We will unlock the f->sem mutex but VFS will use the f->target string. This is safe 59 * since the only way that may cause f->target to be changed is iput() operation. 60 * But VFS will not use f->target after iput() has been called. 61 */ 62 return NULL; 63 } 64 65