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  * @flags: lookup flags
  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, unsigned int flags)
  46 {
  47         struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
  48         int rc = 1;
  49
  50         if (flags & LOOKUP_RCU)
  51                 return -ECHILD;
  52
  53         if (lower_dentry->d_flags & DCACHE_OP_REVALIDATE)
  54                 rc = lower_dentry->d_op->d_revalidate(lower_dentry, flags);
  55
  56         if (d_really_is_positive(dentry)) {
  57                 struct inode *inode = d_inode(dentry);
  58
  59                 fsstack_copy_attr_all(inode, ecryptfs_inode_to_lower(inode));
  60                 if (!inode->i_nlink)
  61                         return 0;
  62         }
  63         return rc;
  64 }
  65
  66 struct kmem_cache *ecryptfs_dentry_info_cache;
  67
  68 static void ecryptfs_dentry_free_rcu(struct rcu_head *head)
  69 {
  70         kmem_cache_free(ecryptfs_dentry_info_cache,
  71                 container_of(head, struct ecryptfs_dentry_info, rcu));
  72 }
  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         struct ecryptfs_dentry_info *p = dentry->d_fsdata;
  83         if (p) {
  84                 path_put(&p->lower_path);
  85                 call_rcu(&p->rcu, ecryptfs_dentry_free_rcu);
  86         }
  87 }
  88
  89 const struct dentry_operations ecryptfs_dops = {
  90         .d_revalidate = ecryptfs_d_revalidate,
  91         .d_release = ecryptfs_d_release,
  92 };