xref: /openbsd-src/usr.sbin/makefs/ffs/ffs_subr.c (revision 8e544e80ad051c7ebb0293f80569ecb775fbd3bf)

/*	$OpenBSD: ffs_subr.c,v 1.6 2022/01/11 05:34:33 jsg Exp $	*/
/*	$NetBSD: ffs_subr.c,v 1.49 2016/05/07 11:59:08 maxv Exp $	*/

/*
 * Copyright (c) 1982, 1986, 1989, 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.
 *
 *	@(#)ffs_subr.c	8.5 (Berkeley) 3/21/95
 */

#include <sys/param.h>	/* setbit clrbit NBBY */
#include <sys/types.h>
#include <ufs/ufs/dinode.h>
#include <ufs/ffs/fs.h>

#include <limits.h>
#include <err.h>

#include "ffs/ffs_extern.h"


/*
 * block operations
 *
 * check if a block is available
 *  returns true if all the corresponding bits in the free map are 1
 *  returns false if any corresponding bit in the free map is 0
 */
int
ffs_isblock(struct fs *fs, u_char *cp, int32_t h)
{
	u_char mask;

	switch ((int)fs->fs_fragshift) {
	case 3:
		return (cp[h] == 0xff);
	case 2:
		mask = 0x0f << ((h & 0x1) << 2);
		return ((cp[h >> 1] & mask) == mask);
	case 1:
		mask = 0x03 << ((h & 0x3) << 1);
		return ((cp[h >> 2] & mask) == mask);
	case 0:
		mask = 0x01 << (h & 0x7);
		return ((cp[h >> 3] & mask) == mask);
	default:
		errx(1, "ffs_isblock: unknown fs_fragshift %d",
		    (int)fs->fs_fragshift);
	}
}

/*
 * take a block out of the map
 */
void
ffs_clrblock(struct fs *fs, u_char *cp, int32_t h)
{

	switch ((int)fs->fs_fragshift) {
	case 3:
		cp[h] = 0;
		return;
	case 2:
		cp[h >> 1] &= ~(0x0f << ((h & 0x1) << 2));
		return;
	case 1:
		cp[h >> 2] &= ~(0x03 << ((h & 0x3) << 1));
		return;
	case 0:
		cp[h >> 3] &= ~(0x01 << (h & 0x7));
		return;
	default:
		errx(1, "ffs_clrblock: unknown fs_fragshift %d",
		    (int)fs->fs_fragshift);
	}
}

/*
 * put a block into the map
 */
void
ffs_setblock(struct fs *fs, u_char *cp, int32_t h)
{

	switch ((int)fs->fs_fragshift) {
	case 3:
		cp[h] = 0xff;
		return;
	case 2:
		cp[h >> 1] |= (0x0f << ((h & 0x1) << 2));
		return;
	case 1:
		cp[h >> 2] |= (0x03 << ((h & 0x3) << 1));
		return;
	case 0:
		cp[h >> 3] |= (0x01 << (h & 0x7));
		return;
	default:
		errx(1, "ffs_setblock: unknown fs_fragshift %d",
		    (int)fs->fs_fragshift);
	}
}

/*
 * Update the cluster map because of an allocation or free.
 *
 * Cnt == 1 means free; cnt == -1 means allocating.
 */
void
ffs_clusteracct(struct fs *fs, struct cg *cgp, int32_t blkno, int cnt)
{
	int32_t *sump;
	int32_t *lp;
	u_char *freemapp, *mapp;
	int i, start, end, forw, back, map, bit;

	/* KASSERT(mutex_owned(&ump->um_lock)); */

	if (fs->fs_contigsumsize <= 0)
		return;
	freemapp = cg_clustersfree(cgp);
	sump = cg_clustersum(cgp);
	/*
	 * Allocate or clear the actual block.
	 */
	if (cnt > 0)
		setbit(freemapp, blkno);
	else
		clrbit(freemapp, blkno);
	/*
	 * Find the size of the cluster going forward.
	 */
	start = blkno + 1;
	end = start + fs->fs_contigsumsize;
	if ((uint32_t)end >= cgp->cg_nclusterblks)
		end = cgp->cg_nclusterblks;
	mapp = &freemapp[start / NBBY];
	map = *mapp++;
	bit = 1 << (start % NBBY);
	for (i = start; i < end; i++) {
		if ((map & bit) == 0)
			break;
		if ((i & (NBBY - 1)) != (NBBY - 1)) {
			bit <<= 1;
		} else {
			map = *mapp++;
			bit = 1;
		}
	}
	forw = i - start;
	/*
	 * Find the size of the cluster going backward.
	 */
	start = blkno - 1;
	end = start - fs->fs_contigsumsize;
	if (end < 0)
		end = -1;
	mapp = &freemapp[start / NBBY];
	map = *mapp--;
	bit = 1 << (start % NBBY);
	for (i = start; i > end; i--) {
		if ((map & bit) == 0)
			break;
		if ((i & (NBBY - 1)) != 0) {
			bit >>= 1;
		} else {
			map = *mapp--;
			bit = 1 << (NBBY - 1);
		}
	}
	back = start - i;
	/*
	 * Account for old cluster and the possibly new forward and
	 * back clusters.
	 */
	i = back + forw + 1;
	if (i > fs->fs_contigsumsize)
		i = fs->fs_contigsumsize;
	sump[i] += cnt;
	if (back > 0)
		sump[back] -= cnt;
	if (forw > 0)
		sump[forw] -= cnt;

	/*
	 * Update cluster summary information.
	 */
	lp = &sump[fs->fs_contigsumsize];
	for (i = fs->fs_contigsumsize; i > 0; i--)
		if (*lp-- > 0)
			break;
}