linux/fs/ecryptfs/dentry.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * eCryptfs: Linux filesystem encryption layer
 *
 * Copyright (C) 1997-2003 Erez Zadok
 * Copyright (C) 2001-2003 Stony Brook University
 * Copyright (C) 2004-2006 International Business Machines Corp.
 *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
 */

#include <linux/dcache.h>
#include <linux/namei.h>
#include <linux/mount.h>
#include <linux/fs_stack.h>
#include <linux/slab.h>
#include "ecryptfs_kernel.h"

/**
 * ecryptfs_d_revalidate - revalidate an ecryptfs dentry
 * @dir: inode of expected parent
 * @name: expected name
 * @dentry: dentry to revalidate
 * @flags: lookup flags
 *
 * Called when the VFS needs to revalidate a dentry. This
 * is called whenever a name lookup finds a dentry in the
 * dcache. Most filesystems leave this as NULL, because all their
 * dentries in the dcache are valid.
 *
 * Returns 1 if valid, 0 otherwise.
 *
 */
static int ecryptfs_d_revalidate(struct inode *dir, const struct qstr *name,
				 struct dentry *dentry, unsigned int flags)
{
	struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
	int rc = 1;

	if (flags & LOOKUP_RCU)
		return -ECHILD;

	if (lower_dentry->d_flags & DCACHE_OP_REVALIDATE) {
		struct inode *lower_dir = ecryptfs_inode_to_lower(dir);
		struct name_snapshot n;

		take_dentry_name_snapshot(&n, lower_dentry);
		rc = lower_dentry->d_op->d_revalidate(lower_dir, &n.name,
						      lower_dentry, flags);
		release_dentry_name_snapshot(&n);
	}

	if (d_really_is_positive(dentry)) {
		struct inode *inode = d_inode(dentry);

		fsstack_copy_attr_all(inode, ecryptfs_inode_to_lower(inode));
		if (!inode->i_nlink)
			return 0;
	}
	return rc;
}

struct kmem_cache *ecryptfs_dentry_info_cache;

static void ecryptfs_dentry_free_rcu(struct rcu_head *head)
{
	kmem_cache_free(ecryptfs_dentry_info_cache,
		container_of(head, struct ecryptfs_dentry_info, rcu));
}

/**
 * ecryptfs_d_release
 * @dentry: The ecryptfs dentry
 *
 * Called when a dentry is really deallocated.
 */
static void ecryptfs_d_release(struct dentry *dentry)
{
	struct ecryptfs_dentry_info *p = dentry->d_fsdata;
	if (p) {
		path_put(&p->lower_path);
		call_rcu(&p->rcu, ecryptfs_dentry_free_rcu);
	}
}

const struct dentry_operations ecryptfs_dops = {
	.d_revalidate = ecryptfs_d_revalidate,
	.d_release = ecryptfs_d_release,
};