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/slab.h> 14 #include <linux/fs.h> 15 #include <linux/namei.h> 16 #include "nodelist.h" 17 18 static void *jffs2_follow_link(struct dentry *dentry, struct nameidata *nd); 19 20 const struct inode_operations jffs2_symlink_inode_operations = 21 { 22 .readlink = generic_readlink, 23 .follow_link = jffs2_follow_link, 24 .check_acl = jffs2_check_acl, 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(dentry->d_inode); 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 printk(KERN_ERR "jffs2_follow_link(): can't find symlink target\n"); 52 p = ERR_PTR(-EIO); 53 } 54 D1(printk(KERN_DEBUG "jffs2_follow_link(): target path is '%s'\n", (char *) f->target)); 55 56 nd_set_link(nd, p); 57 58 /* 59 * We will unlock the f->sem mutex but VFS will use the f->target string. This is safe 60 * since the only way that may cause f->target to be changed is iput() operation. 61 * But VFS will not use f->target after iput() has been called. 62 */ 63 return NULL; 64 } 65 66