/*
 * Copyright (c) 1982, 1986, 1989, 1991, 1993, 1995
 *      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      8.7 (Berkeley) 5/17/95
 * $FreeBSD: src/sys/ufs/ufs/ufs_ihash.c,v 1.20 1999/08/28 00:52:29 peter Exp $
 */

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

#include <vfs/ext2fs/fs.h>
#include <vfs/ext2fs/ext2fs.h>
#include <vfs/ext2fs/inode.h>
#include <vfs/ext2fs/ext2_dinode.h>
#include <vfs/ext2fs/ext2_extern.h>

static MALLOC_DEFINE(M_EXT2IHASH, "EXT2 ihash", "EXT2 Inode hash tables");
/*
 * Structures associated with inode cacheing.
 */
static struct inode **ext2_ihashtbl;
static u_long   ext2_ihash;             /* size of hash table - 1 */
static struct lwkt_token ext2_ihash_token;

#define INOHASH(device, inum)   (&ext2_ihashtbl[(minor(device) + (inum)) & ext2_ihash])

/*
 * Initialize inode hash table.
 */
void
ext2_ihashinit(void)
{
        ext2_ihash = vfs_inodehashsize();
        ext2_ihashtbl = malloc(sizeof(void *) * ext2_ihash, M_EXT2IHASH,
            M_WAITOK | M_ZERO);
        --ext2_ihash;
        lwkt_token_init(&ext2_ihash_token, "ext2ihash");
}

void
ext2_ihashuninit(void)
{
        lwkt_gettoken(&ext2_ihash_token);
        if (ext2_ihashtbl)
                free(ext2_ihashtbl, M_EXT2IHASH);
        lwkt_reltoken(&ext2_ihash_token);
}

/*
 * 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.
 *
 * Note that the serializing tokens do not prevent other processes from
 * playing with the data structure being protected while we are blocked.
 * They do protect us from preemptive interrupts which might try to
 * play with the protected data structure.
 */
struct vnode *
ext2_ihashget(cdev_t dev, ino_t inum)
{
        struct inode *ip;
        struct vnode *vp;

        lwkt_gettoken(&ext2_ihash_token);
loop:
        for (ip = *INOHASH(dev, inum); ip; ip = ip->i_next) {
                if (inum != ip->i_number || dev != ip->i_dev)
                        continue;
                vp = ITOV(ip);
                if (vget(vp, LK_EXCLUSIVE))
                        goto loop;
                /*
                 * We must check to see if the inode has been ripped
                 * out from under us after blocking.
                 */
                for (ip = *INOHASH(dev, inum); ip; ip = ip->i_next) {
                        if (inum == ip->i_number && dev == ip->i_dev)
                                break;
                }
                if (ip == NULL || ITOV(ip) != vp) {
                        vput(vp);
                        goto loop;
                }
                lwkt_reltoken(&ext2_ihash_token);
                return (vp);
        }
        lwkt_reltoken(&ext2_ihash_token);
        return (NULL);
}

/*
 * Insert the inode into the hash table, and return it locked.
 */
int
ext2_ihashins(struct inode *ip)
{
        struct inode **ipp;
        struct inode *iq;

        KKASSERT((ip->i_flag & IN_HASHED) == 0);
        lwkt_gettoken(&ext2_ihash_token);
        ipp = INOHASH(ip->i_dev, ip->i_number);
        while ((iq = *ipp) != NULL) {
                if (ip->i_dev == iq->i_dev && ip->i_number == iq->i_number) {
                        lwkt_reltoken(&ext2_ihash_token);
                        return (EBUSY);
                }
                ipp = &iq->i_next;
        }
        ip->i_next = NULL;
        *ipp = ip;
        ip->i_flag |= IN_HASHED;
        lwkt_reltoken(&ext2_ihash_token);
        return (0);
}

/*
 * Remove the inode from the hash table.
 */
void
ext2_ihashrem(struct inode *ip)
{
        struct inode **ipp;
        struct inode *iq;

        lwkt_gettoken(&ext2_ihash_token);
        if (ip->i_flag & IN_HASHED) {
                ipp = INOHASH(ip->i_dev, ip->i_number);
                while ((iq = *ipp) != NULL) {
                        if (ip == iq)
                                break;
                        ipp = &iq->i_next;
                }
                KKASSERT(ip == iq);
                *ipp = ip->i_next;
                ip->i_next = NULL;
                ip->i_flag &= ~IN_HASHED;
        }
        lwkt_reltoken(&ext2_ihash_token);
}