freebsd-dev/sys/gnu/ext2fs/ext2_ihash.c

/*
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 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.
 *
 *	@(#)ufs_ihash.c	8.4 (Berkeley) 12/30/93
 * $Id: ufs_ihash.c,v 1.4 1994/10/08 06:57:23 phk Exp $
 */

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

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

/*
 * Structures associated with inode cacheing.
 */
struct inode **ihashtbl;
u_long	ihash;		/* size of hash table - 1 */
#define	INOHASH(device, inum)	(((device) + (inum)) & ihash)

/*
 * Initialize inode hash table.
 */
void
ufs_ihashinit()
{

	ihashtbl = hashinit(desiredvnodes, M_UFSMNT, &ihash);
}

/*
 * Use the device/inum pair to find the incore inode, and return a pointer
 * to it. If it is in core, return it, even if it is locked.
 */
struct vnode *
ufs_ihashlookup(device, inum)
	dev_t device;
	ino_t inum;
{
	register struct inode *ip;

	for (ip = ihashtbl[INOHASH(device, inum)];; ip = ip->i_next) {
		if (ip == NULL)
			return (NULL);
		if (inum == ip->i_number && device == ip->i_dev)
			return (ITOV(ip));
	}
	/* NOTREACHED */
}

/*
 * 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(device, inum)
	dev_t device;
	ino_t inum;
{
	register struct inode *ip;
	struct vnode *vp;

	for (;;)
		for (ip = ihashtbl[INOHASH(device, inum)];; ip = ip->i_next) {
			if (ip == NULL)
				return (NULL);
			if (inum == ip->i_number && device == ip->i_dev) {
				if (ip->i_flag & IN_LOCKED) {
					if( curproc->p_pid != ip->i_lockholder) {
						ip->i_flag |= IN_WANTED;
						(void) tsleep(ip, PINOD, "uihget", 0);
						break;
					} else if (ip->i_flag & IN_RECURSE) {
						ip->i_lockcount++;
					} else {
						panic("ufs_ihashget: recursive lock not expected -- pid %d\n", ip->i_lockholder);
					}
				}
				vp = ITOV(ip);
				if (!vget(vp, 1))
					return (vp);
				break;
			}
		}
	/* NOTREACHED */
}

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

	ipp = &ihashtbl[INOHASH(ip->i_dev, ip->i_number)];
	iq = *ipp;
	if (iq)
		iq->i_prev = &ip->i_next;
	ip->i_next = iq;
	ip->i_prev = ipp;
	*ipp = ip;
	if ((ip->i_flag & IN_LOCKED) &&
		((ip->i_flag & IN_RECURSE) == 0 ||
			(!curproc || (curproc && (ip->i_lockholder != curproc->p_pid)))))
		panic("ufs_ihashins: already locked");
	if (curproc)  {
		ip->i_lockcount += 1;
		ip->i_lockholder = curproc->p_pid;
	} else {
		ip->i_lockholder = -1;
	}
	ip->i_flag |= IN_LOCKED;
}

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

	iq = ip->i_next;
	if (iq)
		iq->i_prev = ip->i_prev;
	*ip->i_prev = iq;
#ifdef DIAGNOSTIC
	ip->i_next = NULL;
	ip->i_prev = NULL;
#endif
}