/*
 * Copyright (c) 2019 Apple Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this
 * file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_LICENSE_HEADER_END@
 */

/*-
 * Portions Copyright (c) 1992, 1993
 *  The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software donated to Berkeley by
 * Jan-Simon Pendry.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *  @(#)null_subr.c 8.7 (Berkeley) 5/14/95
 *
 * $FreeBSD$
 */
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mount.h>
#include <sys/proc.h>
#include <sys/vnode.h>

#include "bindfs.h"

/*
 * Null layer cache:
 * Each cache entry holds a reference to the lower vnode
 * along with a pointer to the alias vnode.  When an
 * entry is added the lower vnode is VREF'd.  When the
 * alias is removed the lower vnode is vrele'd.
 */

#define BIND_HASH_SIZE (desiredvnodes / 10)

/* xnu doesn't really have the functionality freebsd uses here..gonna try this
 * hacked hash...*/
#define BIND_NHASH(vp) (&bind_node_hashtbl[((((uintptr_t)vp) >> vnsz2log) + (uintptr_t)vnode_mount(vp)) & bind_hash_mask])

static LIST_HEAD(bind_node_hashhead, bind_node) * bind_node_hashtbl;
static LCK_GRP_DECLARE(bind_hashlck_grp, "com.apple.filesystems.bindfs");
static LCK_MTX_DECLARE(bind_hashmtx, &bind_hashlck_grp);
static u_long bind_hash_mask;

/*  xnu doesn't have hashes built into vnodes. This mimics what freebsd does
 *  9 is an eyeball of the log 2 size of vnode */
static int vnsz2log = 9;

static int bind_hashins(struct mount *, struct bind_node *, struct vnode **);

/*
 * Initialise cache headers
 */
int
bindfs_init(__unused struct vfsconf * vfsp)
{
	BINDFSDEBUG("%s\n", __FUNCTION__);

	bind_node_hashtbl = hashinit(BIND_HASH_SIZE, M_TEMP, &bind_hash_mask);
	if (bind_node_hashtbl == NULL) {
		goto error;
	}

	BINDFSDEBUG("%s finished\n", __FUNCTION__);
	return 0;
error:
	printf("BINDFS: failed to initialize globals\n");
	return KERN_FAILURE;
}

int
bindfs_destroy(void)
{
	/* This gets called when the fs is uninstalled, there wasn't an exact
	 * equivalent in vfsops */
	hashdestroy(bind_node_hashtbl, M_TEMP, bind_hash_mask);
	return 0;
}

/*
 * Find the bindfs vnode mapped to lowervp. Return it in *vpp with an iocount if found.
 * Return 0 on success. On failure *vpp will be NULL and a non-zero error code will be returned.
 */
int
bind_hashget(struct mount * mp, struct vnode * lowervp, struct vnode ** vpp)
{
	struct bind_node_hashhead * hd;
	struct bind_node * a;
	struct vnode * vp = NULL;
	uint32_t vp_vid = 0;
	int error = ENOENT;

	/*
	 * Find hash base, and then search the (two-way)