/*      $OpenBSD: ufs_ihash.c,v 1.31 2024/12/03 14:41:45 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 <ufs/ufs/quota.h>
#include <ufs/ufs/inode.h>
#include <ufs/ufs/ufs_extern.h>
#include <ufs/ufs/ufsmount.h>
#include <ufs/ext2fs/ext2fs_extern.h>

#include <crypto/siphash.h>

/*
 * Structures associated with inode caching.
 */
LIST_HEAD(ihashhead, inode) *ihashtbl;
u_long  ihash;          /* size of hash table - 1 */
SIPHASH_KEY ihashkey;

struct ihashhead *ufs_ihash(dev_t, ufsino_t);
#define INOHASH(device, inum) ufs_ihash((device), (inum))

struct ihashhead *
ufs_ihash(dev_t dev, ufsino_t inum)
{
        SIPHASH_CTX ctx;

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

        return (&ihashtbl[SipHash24_End(&ctx) & ihash]);
}

/*
 * Initialize inode hash table.
 */
void
ufs_ihashinit(void)
{
        ihashtbl = hashinit(initialvnodes, M_UFSMNT, M_WAITOK, &ihash);
        arc4random_buf(&ihashkey, sizeof(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 *
ufs_ihashget(dev_t dev, ufsino_t inum)
{
        struct ihashhead *ipp;
        struct inode *ip;
        struct vnode *vp;
loop:
        /* XXXLOCKING lock hash list */
        ipp = INOHASH(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;
                        /*
                        * Check if the inode is valid.
                        * The condition has been adapted from ufs_inactive().
                        *
                        * This is needed in case our vget above grabbed a vnode
                        * while ufs_inactive was reclaiming it.
                        *
                        * XXX this is a workaround and kind of a gross hack.
                        * realistically this should get fixed something like
                        * the previously committed vdoom() or this should be
                        * dealt with so this can't happen.
                        */
                        if (VTOI(vp) != ip ||
                            ((
#ifdef EXT2FS
                            /*
                             * XXX DIP does not cover ext2fs so hack
                             * around this for now since this is using
                             * ufs_ihashget as well.
                             */
                            IS_EXT2_VNODE(vp) ? ip->i_e2fs_nlink <= 0 :
#endif
                            DIP(ip, nlink) <= 0) &&
                             (vp->v_mount->mnt_flag & MNT_RDONLY) == 0)) {
                                /*
                                 * This should recycle the inode immediately,
                                 * unless there are other threads that
                                 * try to access it.
                                 * Pause to give the threads a chance to finish
                                 * with the inode.
                                 */
                                vput(vp);
                                yield();
                                goto loop;
                        }

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

/*
 * Insert the inode into the hash table, and return it locked.
 */
int
ufs_ihashins(struct inode *ip)
{
        struct   inode *curip;
        struct   ihashhead *ipp;
        dev_t    dev = ip->i_dev;
        ufsino_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 = INOHASH(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);
                }
        }

        SET(ip->i_flag, IN_HASHED);
        LIST_INSERT_HEAD(ipp, ip, i_hash);
        /* XXXLOCKING unlock hash list? */

        return (0);
}

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

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