release/src-rt-6.x.4708/linux/linux-2.6.36/fs/ecryptfs/dentry.c

   1 /**
   2  * eCryptfs: Linux filesystem encryption layer
   3  *
   4  * Copyright (C) 1997-2003 Erez Zadok
   5  * Copyright (C) 2001-2003 Stony Brook University
   6  * Copyright (C) 2004-2006 International Business Machines Corp.
   7  *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
   8  *
   9  * This program is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU General Public License as
  11  * published by the Free Software Foundation; either version 2 of the
  12  * License, or (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful, but
  15  * WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with this program; if not, write to the Free Software
  21  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  22  * 02111-1307, USA.
  23  */
  24
  25 #include <linux/dcache.h>
  26 #include <linux/namei.h>
  27 #include <linux/mount.h>
  28 #include <linux/fs_stack.h>
  29 #include <linux/slab.h>
  30 #include "ecryptfs_kernel.h"
  31
  32 /**
  33  * ecryptfs_d_revalidate - revalidate an ecryptfs dentry
  34  * @dentry: The ecryptfs dentry
  35  * @nd: The associated nameidata
  36  *
  37  * Called when the VFS needs to revalidate a dentry. This
  38  * is called whenever a name lookup finds a dentry in the
  39  * dcache. Most filesystems leave this as NULL, because all their
  40  * dentries in the dcache are valid.
  41  *
  42  * Returns 1 if valid, 0 otherwise.
  43  *
  44  */
  45 static int ecryptfs_d_revalidate(struct dentry *dentry, struct nameidata *nd)
  46 {
  47         struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
  48         struct vfsmount *lower_mnt = ecryptfs_dentry_to_lower_mnt(dentry);
  49         struct dentry *dentry_save;
  50         struct vfsmount *vfsmount_save;
  51         int rc = 1;
  52
  53         if (!lower_dentry->d_op || !lower_dentry->d_op->d_revalidate)
  54                 goto out;
  55         dentry_save = nd->path.dentry;
  56         vfsmount_save = nd->path.mnt;
  57         nd->path.dentry = lower_dentry;
  58         nd->path.mnt = lower_mnt;
  59         rc = lower_dentry->d_op->d_revalidate(lower_dentry, nd);
  60         nd->path.dentry = dentry_save;
  61         nd->path.mnt = vfsmount_save;
  62         if (dentry->d_inode) {
  63                 struct inode *lower_inode =
  64                         ecryptfs_inode_to_lower(dentry->d_inode);
  65
  66                 fsstack_copy_attr_all(dentry->d_inode, lower_inode);
  67         }
  68 out:
  69         return rc;
  70 }
  71
  72 struct kmem_cache *ecryptfs_dentry_info_cache;
  73
  74 /**
  75  * ecryptfs_d_release
  76  * @dentry: The ecryptfs dentry
  77  *
  78  * Called when a dentry is really deallocated.
  79  */
  80 static void ecryptfs_d_release(struct dentry *dentry)
  81 {
  82         if (ecryptfs_dentry_to_private(dentry)) {
  83                 if (ecryptfs_dentry_to_lower(dentry)) {
  84                         dput(ecryptfs_dentry_to_lower(dentry));
  85                         mntput(ecryptfs_dentry_to_lower_mnt(dentry));
  86                 }
  87                 kmem_cache_free(ecryptfs_dentry_info_cache,
  88                                 ecryptfs_dentry_to_private(dentry));
  89         }
  90         return;
  91 }
  92
  93 const struct dentry_operations ecryptfs_dops = {
  94         .d_revalidate = ecryptfs_d_revalidate,
  95         .d_release = ecryptfs_d_release,
  96 };