usr/src/sys/ufs/ffs/ufs_ihash.c

/*
 * Copyright (c) 1982, 1986, 1989, 1991 Regents of the University of California.
 * All rights reserved.
 *
 * %sccs.include.redist.c%
 *
 *      @(#)ufs_ihash.c 7.3 (Berkeley) %G%
 */

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

#include <ufs/ufs/quota.h>
#include <ufs/ufs/inode.h>
#include <ufs/ufs/ufs_extern.h>

/*
 * Structures associated with inode cacheing.
 */
union ihash {
        union   ihash *ih_head[2];
        struct  inode *ih_chain[2];
} *ihashtbl;
#define ih_forw ih_chain[0]
#define ih_back ih_chain[1]

u_long  ihash;                  /* size of hash table - 1 */
#define INOHASH(dev, ino)       (((dev) + (ino)) & ihash)

/*
 * Initialize inode hash table.
 */
void
ufs_ihashinit()
{
        register union ihash *ihp;
        long ihashsize;

        ihashsize = roundup((desiredvnodes + 1) * sizeof *ihp / 2,
                NBPG * CLSIZE);
        ihashtbl = (union ihash *)malloc((u_long)ihashsize,
            M_UFSMNT, M_WAITOK);
        for (ihash = 1; ihash <= ihashsize / sizeof *ihp; ihash <<= 1)
                /* void */;
        ihash = (ihash >> 1) - 1;
        for (ihp = &ihashtbl[ihash]; ihp >= ihashtbl; ihp--) {
                ihp->ih_head[0] = ihp;
                ihp->ih_head[1] = ihp;
        }
}

/*
 * Use the dev/ino 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, ino)
        /* dev_t */ int dev;
        ino_t ino;
{
        register union ihash *ihp;
        register struct inode *ip;
        struct vnode *vp;

        ihp = &ihashtbl[INOHASH(dev, ino)];
loop:
        for (ip = ihp->ih_forw; ip != (struct inode *)ihp; ip = ip->i_forw) {
                if (ino != ip->i_number || dev != ip->i_dev)
                        continue;
                if ((ip->i_flag & ILOCKED) != 0) {
                        ip->i_flag |= IWANT;
                        sleep((caddr_t)ip, PINOD);
                        goto loop;
                }
                vp = ITOV(ip);
                if (vget(vp))
                        goto loop;
                return (vp);
        }
        return (NULL);
}

/*
 * Insert the inode into the hash table, and return it locked.
 */
void
ufs_ihashins(ip)
        struct inode *ip;
{
        insque(ip, &ihashtbl[INOHASH(ip->i_dev, ip->i_number)]);
        ILOCK(ip);
}