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 * @dir: inode of expected parent
21 * @name: expected name
22 * @dentry: dentry to revalidate
23 * @flags: lookup flags
24 *
25 * Called when the VFS needs to revalidate a dentry. This
26 * is called whenever a name lookup finds a dentry in the
27 * dcache. Most filesystems leave this as NULL, because all their
28 * dentries in the dcache are valid.
29 *
30 * Returns 1 if valid, 0 otherwise.
31 *
32 */
33static int ecryptfs_d_revalidate(struct inode *dir, const struct qstr *name,
34				 struct dentry *dentry, unsigned int flags)
35{
36	struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
37	int rc = 1;
38
39	if (flags & LOOKUP_RCU)
40		return -ECHILD;
41
42	if (lower_dentry->d_flags & DCACHE_OP_REVALIDATE) {
43		struct inode *lower_dir = ecryptfs_inode_to_lower(dir);
44		struct name_snapshot n;
45
46		take_dentry_name_snapshot(&n, lower_dentry);
47		rc = lower_dentry->d_op->d_revalidate(lower_dir, &n.name,
48						      lower_dentry, flags);
49		release_dentry_name_snapshot(&n);
50	}
51
52	if (d_really_is_positive(dentry)) {
53		struct inode *inode = d_inode(dentry);
54
55		fsstack_copy_attr_all(inode, ecryptfs_inode_to_lower(inode));
56		if (!inode->i_nlink)
57			return 0;
58	}
59	return rc;
60}
61
62/**
63 * ecryptfs_d_release
64 * @dentry: The ecryptfs dentry
65 *
66 * Called when a dentry is really deallocated.
67 */
68static void ecryptfs_d_release(struct dentry *dentry)
69{
70	dput(dentry->d_fsdata);
71}
72
73const struct dentry_operations ecryptfs_dops = {
74	.d_revalidate = ecryptfs_d_revalidate,
75	.d_release = ecryptfs_d_release,
76};