fs/ecryptfs/dentry.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /**
   3  * eCryptfs: Linux filesystem encryption layer
   4  *
   5  * Copyright (C) 1997-2003 Erez Zadok
   6  * Copyright (C) 2001-2003 Stony Brook University
   7  * Copyright (C) 2004-2006 International Business Machines Corp.
   8  *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
   9  */
  10
  11 #include <linux/dcache.h>
  12 #include <linux/namei.h>
  13 #include <linux/mount.h>
  14 #include <linux/fs_stack.h>
  15 #include <linux/slab.h>
  16 #include "ecryptfs_kernel.h"
  17
  18 /**
  19  * ecryptfs_d_revalidate - revalidate an ecryptfs dentry
  20  * @dentry: The ecryptfs dentry
  21  * @flags: lookup flags
  22  *
  23  * Called when the VFS needs to revalidate a dentry. This
  24  * is called whenever a name lookup finds a dentry in the
  25  * dcache. Most filesystems leave this as NULL, because all their
  26  * dentries in the dcache are valid.
  27  *
  28  * Returns 1 if valid, 0 otherwise.
  29  *
  30  */
  31 static int ecryptfs_d_revalidate(struct dentry *dentry, unsigned int flags)
  32 {
  33         struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
  34         int rc = 1;
  35
  36         if (flags & LOOKUP_RCU)
  37                 return -ECHILD;
  38
  39         if (lower_dentry->d_flags & DCACHE_OP_REVALIDATE)
  40                 rc = lower_dentry->d_op->d_revalidate(lower_dentry, flags);
  41
  42         if (d_really_is_positive(dentry)) {
  43                 struct inode *inode = d_inode(dentry);
  44
  45                 fsstack_copy_attr_all(inode, ecryptfs_inode_to_lower(inode));
  46                 if (!inode->i_nlink)
  47                         return 0;
  48         }
  49         return rc;
  50 }
  51
  52 struct kmem_cache *ecryptfs_dentry_info_cache;
  53
  54 static void ecryptfs_dentry_free_rcu(struct rcu_head *head)
  55 {
  56         kmem_cache_free(ecryptfs_dentry_info_cache,
  57                 container_of(head, struct ecryptfs_dentry_info, rcu));
  58 }
  59
  60 /**
  61  * ecryptfs_d_release
  62  * @dentry: The ecryptfs dentry
  63  *
  64  * Called when a dentry is really deallocated.
  65  */
  66 static void ecryptfs_d_release(struct dentry *dentry)
  67 {
  68         struct ecryptfs_dentry_info *p = dentry->d_fsdata;
  69         if (p) {
  70                 path_put(&p->lower_path);
  71                 call_rcu(&p->rcu, ecryptfs_dentry_free_rcu);
  72         }
  73 }
  74
  75 const struct dentry_operations ecryptfs_dops = {
  76         .d_revalidate = ecryptfs_d_revalidate,
  77         .d_release = ecryptfs_d_release,
  78 };