LXR linux/fs/jffs2/symlink.c

   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
  18static void *jffs2_follow_link(struct dentry *dentry, struct nameidata *nd);
  19
  20const struct inode_operations jffs2_symlink_inode_operations =
  21{
  22        .readlink =     generic_readlink,
  23        .follow_link =  jffs2_follow_link,
  24        .permission =   jffs2_permission,
  25        .setattr =      jffs2_setattr,
  26        .setxattr =     jffs2_setxattr,
  27        .getxattr =     jffs2_getxattr,
  28        .listxattr =    jffs2_listxattr,
  29        .removexattr =  jffs2_removexattr
  30};
  31
  32static 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