/*      $OpenBSD: fuse_ihash.c,v 1.1 2024/10/31 13:55:21 claudio Exp $  */
/*      $NetBSD: ufs_ihash.c,v 1.3 1996/02/09 22:36:04 christos Exp $   */

/*
 * Copyright (c) 1982, 1986, 1989, 1991, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * 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.
 * 3. 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.
 *
 *      @(#)ufs_ihash.c 8.4 (Berkeley) 12/30/93
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/vnode.h>
#include <sys/malloc.h>
#include <sys/mount.h>
#include <sys/lock.h>

#include "fusefs_node.h"

#include <crypto/siphash.h>

/*
 * Structures associated with inode caching.
 */
LIST_HEAD(fuse_ihashhead, fusefs_node) *fuse_ihashtbl;
u_long  fuse_ihashsz;           /* size of hash table - 1 */
SIPHASH_KEY fuse_ihashkey;

struct fuse_ihashhead *fuse_ihash(dev_t, ino_t);

struct fuse_ihashhead *
fuse_ihash(dev_t dev, ino_t inum)
{
        SIPHASH_CTX ctx;

        SipHash24_Init(&ctx, &fuse_ihashkey);
        SipHash24_Update(&ctx, &dev, sizeof(dev));
        SipHash24_Update(&ctx, &inum, sizeof(inum));

        return (&fuse_ihashtbl[SipHash24_End(&ctx) & fuse_ihashsz]);
}

/*
 * Initialize inode hash table.
 */
void
fuse_ihashinit(void)
{
        fuse_ihashtbl = hashinit(initialvnodes, M_FUSEFS, M_WAITOK,
            &fuse_ihashsz);
        arc4random_buf(&fuse_ihashkey, sizeof(fuse_ihashkey));
}

/*
 * Use the device/inum pair to find the incore inode, and return a pointer
 * to it. If it is in core, but locked, wait for it.
 */
struct vnode *
fuse_ihashget(dev_t dev, ino_t inum)
{
        struct fuse_ihashhead *ipp;
        struct fusefs_node *ip;
        struct vnode *vp;
loop:
        /* XXXLOCKING lock hash list */
        ipp = fuse_ihash(dev, inum);
        LIST_FOREACH(ip, ipp, i_hash) {
                if (inum == ip->i_number && dev == ip->i_dev) {
                        vp = ITOV(ip);
                        /* XXXLOCKING unlock hash list? */
                        if (vget(vp, LK_EXCLUSIVE))
                                goto loop;

                        return (vp);
                }
        }
        /* XXXLOCKING unlock hash list? */
        return (NULL);
}

/*
 * Insert the inode into the hash table, and return it locked.
 */
int
fuse_ihashins(struct fusefs_node *ip)
{
        struct   fusefs_node *curip;
        struct   fuse_ihashhead *ipp;
        dev_t    dev = ip->i_dev;
        ino_t    inum = ip->i_number;

        /* lock the inode, then put it on the appropriate hash list */
        VOP_LOCK(ITOV(ip), LK_EXCLUSIVE);

        /* XXXLOCKING lock hash list */

        ipp = fuse_ihash(dev, inum);
        LIST_FOREACH(curip, ipp, i_hash) {
                if (inum == curip->i_number && dev == curip->i_dev) {
                        /* XXXLOCKING unlock hash list? */
                        VOP_UNLOCK(ITOV(ip));
                        return (EEXIST);
                }
        }

        LIST_INSERT_HEAD(ipp, ip, i_hash);
        /* XXXLOCKING unlock hash list? */

        return (0);
}

/*
 * Remove the inode from the hash table.
 */
void
fuse_ihashrem(struct fusefs_node *ip)
{
        /* XXXLOCKING lock hash list */

        if (ip->i_hash.le_prev == NULL)
                return;
        LIST_REMOVE(ip, i_hash);
#ifdef DIAGNOSTIC
        ip->i_hash.le_next = NULL;
        ip->i_hash.le_prev = NULL;
#endif
        /* XXXLOCKING unlock hash list? */
}