[unix-history] / usr / src / sbin / newfs / mkfs.c

/*
 * Copyright (c) 1980 Regents of the University of California.
 * All rights reserved.  The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 */

#ifndef lint
static char sccsid[] = "@(#)mkfs.c	6.7 (Berkeley) %G%";
#endif not lint

#ifndef STANDALONE
#include <stdio.h>
#include <a.out.h>
#endif

#include <sys/param.h>
#include <sys/inode.h>
#include <sys/fs.h>
#include <sys/dir.h>
#include <sys/disklabel.h>
#include <machine/endian.h>

/*
 * make file system for cylinder-group style file systems
 */

/*
 * The size of a cylinder group is calculated by CGSIZE. The maximum size
 * is limited by the fact that cylinder groups are at most one block.
 * Its size is derived from the size of the maps maintained in the 
 * cylinder group and the (struct cg) size.
 */
#define CGSIZE(fs) \
    /* base cg */	(sizeof(struct cg) + \
    /* blktot size */	(fs)->fs_cpg * sizeof(long) + \
    /* blks size */	(fs)->fs_cpg * (fs)->fs_nrpos * sizeof(short) + \
    /* inode map */	howmany((fs)->fs_ipg, NBBY) + \
    /* block map */	howmany((fs)->fs_cpg * (fs)->fs_spc / NSPF(fs), NBBY))

/*
 * We limit the size of the inode map to be no more than a
 * third of the cylinder group space, since we must leave at
 * least an equal amount of space for the block map.
 *
 * N.B.: MAXIPG must be a multiple of INOPB(fs).
 */
#define MAXIPG(fs)	roundup((fs)->fs_bsize * NBBY / 3, INOPB(fs))

#define UMASK		0755
#define MAXINOPB	(MAXBSIZE / sizeof(struct dinode))
#define POWEROF2(num)	(((num) & ((num) - 1)) == 0)

/*
 * variables set up by front end.
 */
extern int	Nflag;		/* run mkfs without writing file system */
extern int	fssize;		/* file system size */
extern int	ntracks;	/* # tracks/cylinder */
extern int	nsectors;	/* # sectors/track */
extern int	nphyssectors;	/* # sectors/track including spares */
extern int	secpercyl;	/* sectors per cylinder */
extern int	sectorsize;	/* bytes/sector */
extern int	rpm;		/* revolutions/minute of drive */
extern int	interleave;	/* hardware sector interleave */
extern int	trackskew;	/* sector 0 skew, per track */
extern int	headswitch;	/* head switch time, usec */
extern int	trackseek;	/* track-to-track seek, usec */
extern int	fsize;		/* fragment size */
extern int	bsize;		/* block size */
extern int	cpg;		/* cylinders/cylinder group */
extern int	cpgflg;		/* cylinders/cylinder group flag was given */
extern int	minfree;	/* free space threshold */
extern int	opt;		/* optimization preference (space or time) */
extern int	density;	/* number of bytes per inode */
extern int	maxcontig;	/* max contiguous blocks to allocate */
extern int	rotdelay;	/* rotational delay between blocks */
extern int	maxbpg;		/* maximum blocks per file in a cyl group */
extern int	nrpos;		/* # of distinguished rotational positions */
extern int	bbsize;		/* boot block size */
extern int	sbsize;		/* superblock size */

union {
	struct fs fs;
	char pad[SBSIZE];
} fsun;
#define	sblock	fsun.fs
struct	csum *fscs;

union {
	struct cg cg;
	char pad[MAXBSIZE];
} cgun;
#define	acg	cgun.cg

struct dinode zino[MAXBSIZE / sizeof(struct dinode)];

int	fsi, fso;
time_t	utime;
daddr_t	alloc();

mkfs(pp, fsys, fi, fo)
	struct partition *pp;
	char *fsys;
	int fi, fo;
{
	register long i, mincpc, mincpg, inospercg;
	long cylno, rpos, blk, j, warn = 0;
	long used, mincpgcnt, bpcg;
	long mapcramped, inodecramped;
	long postblsize, rotblsize, totalsbsize;

#ifndef STANDALONE
	time(&utime);
#endif
	fsi = fi;
	fso = fo;
	/*
	 * Validate the given file system size.
	 * Verify that its last block can actually be accessed.
	 */
	if (fssize <= 0)
		printf("preposterous size %d\n", fssize), exit(1);
	wtfs(fssize - 1, sectorsize, (char *)&sblock);
	/*
	 * collect and verify the sector and track info
	 */
	sblock.fs_nsect = nsectors;
	sblock.fs_ntrak = ntracks;
	if (sblock.fs_ntrak <= 0)
		printf("preposterous ntrak %d\n", sblock.fs_ntrak), exit(1);
	if (sblock.fs_nsect <= 0)
		printf("preposterous nsect %d\n", sblock.fs_nsect), exit(1);
	/*
	 * collect and verify the block and fragment sizes
	 */
	sblock.fs_bsize = bsize;
	sblock.fs_fsize = fsize;
	if (!POWEROF2(sblock.fs_bsize)) {
		printf("block size must be a power of 2, not %d\n",
		    sblock.fs_bsize);
		exit(1);
	}
	if (!POWEROF2(sblock.fs_fsize)) {
		printf("fragment size must be a power of 2, not %d\n",
		    sblock.fs_fsize);
		exit(1);
	}
	if (sblock.fs_fsize < sectorsize) {
		printf("fragment size %d is too small, minimum is %d\n",
		    sblock.fs_fsize, sectorsize);
		exit(1);
	}
	if (sblock.fs_bsize < MINBSIZE) {
		printf("block size %d is too small, minimum is %d\n",
		    sblock.fs_bsize, MINBSIZE);
		exit(1);
	}
	if (sblock.fs_bsize < sblock.fs_fsize) {
		printf("block size (%d) cannot be smaller than fragment size (%d)\n",
		    sblock.fs_bsize, sblock.fs_fsize);
		exit(1);
	}
	sblock.fs_bmask = ~(sblock.fs_bsize - 1);
	sblock.fs_fmask = ~(sblock.fs_fsize - 1);
	/*
	 * Planning now for future expansion.
	 */
#	if (BYTE_ORDER == BIG_ENDIAN)
		sblock.fs_qbmask.val[0] = 0;
		sblock.fs_qbmask.val[1] = ~sblock.fs_bmask;
		sblock.fs_qfmask.val[0] = 0;
		sblock.fs_qfmask.val[1] = ~sblock.fs_fmask;
#	endif /* BIG_ENDIAN */
#	if (BYTE_ORDER == LITTLE_ENDIAN)
		sblock.fs_qbmask.val[0] = ~sblock.fs_bmask;
		sblock.fs_qbmask.val[1] = 0;
		sblock.fs_qfmask.val[0] = ~sblock.fs_fmask;
		sblock.fs_qfmask.val[1] = 0;
#	endif /* LITTLE_ENDIAN */
	for (sblock.fs_bshift = 0, i = sblock.fs_bsize; i > 1; i >>= 1)
		sblock.fs_bshift++;
	for (sblock.fs_fshift = 0, i = sblock.fs_fsize; i > 1; i >>= 1)
		sblock.fs_fshift++;
	sblock.fs_frag = numfrags(&sblock, sblock.fs_bsize);
	for (sblock.fs_fragshift = 0, i = sblock.fs_frag; i > 1; i >>= 1)
		sblock.fs_fragshift++;
	if (sblock.fs_frag > MAXFRAG) {
		printf("fragment size %d is too small, minimum with block size %d is %d\n",
		    sblock.fs_fsize, sblock.fs_bsize,
		    sblock.fs_bsize / MAXFRAG);
		exit(1);
	}
	sblock.fs_nrpos = nrpos;
	sblock.fs_nindir = sblock.fs_bsize / sizeof(daddr_t);
	sblock.fs_inopb = sblock.fs_bsize / sizeof(struct dinode);
	sblock.fs_nspf = sblock.fs_fsize / sectorsize;
	for (sblock.fs_fsbtodb = 0, i = NSPF(&sblock); i > 1; i >>= 1)
		sblock.fs_fsbtodb++;
	sblock.fs_sblkno =
	    roundup(howmany(bbsize + sbsize, sblock.fs_fsize), sblock.fs_frag);
	sblock.fs_cblkno = (daddr_t)(sblock.fs_sblkno +
	    roundup(howmany(sbsize, sblock.fs_fsize), sblock.fs_frag));
	sblock.fs_iblkno = sblock.fs_cblkno + sblock.fs_frag;
	sblock.fs_cgoffset = roundup(
	    howmany(sblock.fs_nsect, NSPF(&sblock)), sblock.fs_frag);
	for (sblock.fs_cgmask = 0xffffffff, i = sblock.fs_ntrak; i > 1; i >>= 1)
		sblock.fs_cgmask <<= 1;
	if (!POWEROF2(sblock.fs_ntrak))
		sblock.fs_cgmask <<= 1;
	/*
	 * Validate specified/determined secpercyl
	 * and calculate minimum cylinders per group.
	 */
	sblock.fs_spc = secpercyl;
	for (sblock.fs_cpc = NSPB(&sblock), i = sblock.fs_spc;
	     sblock.fs_cpc > 1 && (i & 1) == 0;
	     sblock.fs_cpc >>= 1, i >>= 1)
		/* void */;
	mincpc = sblock.fs_cpc;
	bpcg = sblock.fs_spc * sectorsize;
	inospercg = roundup(bpcg / sizeof(struct dinode), INOPB(&sblock));
	if (inospercg > MAXIPG(&sblock))
		inospercg = MAXIPG(&sblock);
	used = (sblock.fs_iblkno + inospercg / INOPF(&sblock)) * NSPF(&sblock);
	mincpgcnt = howmany(sblock.fs_cgoffset * (~sblock.fs_cgmask) + used,
	    sblock.fs_spc);
	mincpg = roundup(mincpgcnt, mincpc);
	/*
	 * Insure that cylinder group with mincpg has enough space
	 * for block maps
	 */
	sblock.fs_cpg = mincpg;
	sblock.fs_ipg = inospercg;
	mapcramped = 0;
	while (CGSIZE(&sblock) > sblock.fs_bsize) {
		mapcramped = 1;
		if (sblock.fs_bsize < MAXBSIZE) {
			sblock.fs_bsize <<= 1;
			if ((i & 1) == 0) {
				i >>= 1;
			} else {
				sblock.fs_cpc <<= 1;
				mincpc <<= 1;
				mincpg = roundup(mincpgcnt, mincpc);
				sblock.fs_cpg = mincpg;
			}
			sblock.fs_frag <<= 1;
			sblock.fs_fragshift += 1;
			if (sblock.fs_frag <= MAXFRAG)
				continue;
		}
		if (sblock.fs_fsize == sblock.fs_bsize) {
			printf("There is no block size that");
			printf(" can support this disk\n");
			exit(1);
		}
		sblock.fs_frag >>= 1;
		sblock.fs_fragshift -= 1;
		sblock.fs_fsize <<= 1;
		sblock.fs_nspf <<= 1;
	}
	/*
	 * Insure that cylinder group with mincpg has enough space for inodes
	 */
	inodecramped = 0;
	used *= sectorsize;
	inospercg = roundup((mincpg * bpcg - used) / density, INOPB(&sblock));
	sblock.fs_ipg = inospercg;
	while (inospercg > MAXIPG(&sblock)) {
		inodecramped = 1;
		if (mincpc == 1 || sblock.fs_frag == 1 ||
		    sblock.fs_bsize == MINBSIZE)
			break;
		printf("With a block size of %d %s %d\n", sblock.fs_bsize,
		    "minimum bytes per inode is",
		    (mincpg * bpcg - used) / MAXIPG(&sblock) + 1);
		sblock.fs_bsize >>= 1;
		sblock.fs_frag >>= 1;
		sblock.fs_fragshift -= 1;
		mincpc >>= 1;
		sblock.fs_cpg = roundup(mincpgcnt, mincpc);
		if (CGSIZE(&sblock) > sblock.fs_bsize) {
			sblock.fs_bsize <<= 1;
			break;
		}
		mincpg = sblock.fs_cpg;
		inospercg =
		    roundup((mincpg * bpcg - used) / density, INOPB(&sblock));
		sblock.fs_ipg = inospercg;
	}
	if (inodecramped) {
		if (inospercg > MAXIPG(&sblock)) {
			printf("Minimum bytes per inode is %d\n",
			    (mincpg * bpcg - used) / MAXIPG(&sblock) + 1);
		} else if (!mapcramped) {
			printf("With %d bytes per inode, ", density);
			printf("minimum cylinders per group is %d\n", mincpg);
		}
	}
	if (mapcramped) {
		printf("With %d sectors per cylinder, ", sblock.fs_spc);
		printf("minimum cylinders per group is %d\n", mincpg);
	}
	if (inodecramped || mapcramped) {
		if (sblock.fs_bsize != bsize)
			printf("%s to be changed from %d to %d\n",
			    "This requires the block size",
			    bsize, sblock.fs_bsize);
		if (sblock.fs_fsize != fsize)
			printf("\t%s to be changed from %d to %d\n",
			    "and the fragment size",
			    fsize, sblock.fs_fsize);
		exit(1);
	}
	/* 
	 * Calculate the number of cylinders per group
	 */
	sblock.fs_cpg = cpg;
	if (sblock.fs_cpg % mincpc != 0) {
		printf("%s groups must have a multiple of %d cylinders\n",
			cpgflg ? "Cylinder" : "Warning: cylinder", mincpc);
		sblock.fs_cpg = roundup(sblock.fs_cpg, mincpc);
		if (!cpgflg)
			cpg = sblock.fs_cpg;
	}
	/*
	 * Must insure there is enough space for inodes
	 */
	sblock.fs_ipg = roundup((sblock.fs_cpg * bpcg - used) / density,
		INOPB(&sblock));
	while (sblock.fs_ipg > MAXIPG(&sblock)) {
		inodecramped = 1;
		sblock.fs_cpg -= mincpc;
		sblock.fs_ipg = roundup((sblock.fs_cpg * bpcg - used) / density,
			INOPB(&sblock));
	}
	/*
	 * Must insure there is enough space to hold block map
	 */
	while (CGSIZE(&sblock) > sblock.fs_bsize) {
		mapcramped = 1;
		sblock.fs_cpg -= mincpc;
		sblock.fs_ipg = roundup((sblock.fs_cpg * bpcg - used) / density,
			INOPB(&sblock));
	}
	sblock.fs_fpg = (sblock.fs_cpg * sblock.fs_spc) / NSPF(&sblock);
	if ((sblock.fs_cpg * sblock.fs_spc) % NSPB(&sblock) != 0) {
		printf("newfs: panic (fs_cpg * fs_spc) % NSPF != 0");
		exit(2);
	}
	if (sblock.fs_cpg < mincpg) {
		printf("cylinder groups must have at least %d cylinders\n",
			mincpg);
		exit(1);
	} else if (sblock.fs_cpg != cpg) {
		if (!cpgflg)
			printf("Warning: ");
		else if (!mapcramped && !inodecramped)
			exit(1);
		if (mapcramped && inodecramped)
			printf("Block size and bytes per inode restrict");
		else if (mapcramped)
			printf("Block size restricts");
		else
			printf("Bytes per inode restrict");
		printf(" cylinders per group to %d.\n", sblock.fs_cpg);
		if (cpgflg)
			exit(1);
	}
	sblock.fs_cgsize = fragroundup(&sblock, CGSIZE(&sblock));
	/*
	 * Now have size for file system and nsect and ntrak.
	 * Determine number of cylinders and blocks in the file system.
	 */
	sblock.fs_size = fssize = dbtofsb(&sblock, fssize);
	sblock.fs_ncyl = fssize * NSPF(&sblock) / sblock.fs_spc;
	if (fssize * NSPF(&sblock) > sblock.fs_ncyl * sblock.fs_spc) {
		sblock.fs_ncyl++;
		warn = 1;
	}
	if (sblock.fs_ncyl < 1) {
		printf("file systems must have at least one cylinder\n");
		exit(1);
	}
	/*
	 * Determine feasability/values of rotational layout tables.
	 *
	 * The size of the rotational layout tables is limited by the
	 * size of the superblock, SBSIZE. The amount of space available
	 * for tables is calculated as (SBSIZE - sizeof (struct fs)).
	 * The size of these tables is inversely proportional to the block
	 * size of the file system. The size increases if sectors per track
	 * are not powers of two, because more cylinders must be described
	 * by the tables before the rotational pattern repeats (fs_cpc).
	 */
	sblock.fs_interleave = interleave;
	sblock.fs_trackskew = trackskew;
	sblock.fs_npsect = nphyssectors;
	sblock.fs_postblformat = FS_DYNAMICPOSTBLFMT;
	sblock.fs_sbsize = fragroundup(&sblock, sizeof(struct fs));
	if (sblock.fs_ntrak == 1) {
		sblock.fs_cpc = 0;
		goto next;
	}
	postblsize = sblock.fs_nrpos * sblock.fs_cpc * sizeof(short);
	rotblsize = sblock.fs_cpc * sblock.fs_spc / NSPB(&sblock);
	totalsbsize = sizeof(struct fs) + rotblsize;
	if (sblock.fs_nrpos == 8 && sblock.fs_cpc <= 16) {
		/* use old static table space */
		sblock.fs_postbloff = (char *)(&sblock.fs_opostbl[0][0]) -
		    (char *)(&sblock.fs_link);
		sblock.fs_rotbloff = &sblock.fs_space[0] -
		    (u_char *)(&sblock.fs_link);
	} else {
		/* use dynamic table space */
		sblock.fs_postbloff = &sblock.fs_space[0] -
		    (u_char *)(&sblock.fs_link);
		sblock.fs_rotbloff = sblock.fs_postbloff + postblsize;
		totalsbsize += postblsize;
	}
	if (totalsbsize > SBSIZE ||
	    sblock.fs_nsect > (1 << NBBY) * NSPB(&sblock)) {
		printf("%s %s %d %s %d.%s",
		    "Warning: insufficient space in super block for\n",
		    "rotational layout tables with nsect", sblock.fs_nsect,
		    "and ntrak", sblock.fs_ntrak,
		    "\nFile system performance may be impared.\n");
		sblock.fs_cpc = 0;
		goto next;
	}
	sblock.fs_sbsize = fragroundup(&sblock, totalsbsize);
	/*
	 * calculate the available blocks for each rotational position
	 */
	for (cylno = 0; cylno < sblock.fs_cpc; cylno++)
		for (rpos = 0; rpos < sblock.fs_nrpos; rpos++)
			fs_postbl(&sblock, cylno)[rpos] = -1;
	for (i = (rotblsize - 1) * sblock.fs_frag;
	     i >= 0; i -= sblock.fs_frag) {
		cylno = cbtocylno(&sblock, i);
		rpos = cbtorpos(&sblock, i);
		blk = fragstoblks(&sblock, i);
		if (fs_postbl(&sblock, cylno)[rpos] == -1)
			fs_rotbl(&sblock)[blk] = 0;
		else
			fs_rotbl(&sblock)[blk] =
			    fs_postbl(&sblock, cylno)[rpos] - blk;
		fs_postbl(&sblock, cylno)[rpos] = blk;
	}
next:
	/*
	 * Compute/validate number of cylinder groups.
	 */
	sblock.fs_ncg = sblock.fs_ncyl / sblock.fs_cpg;
	if (sblock.fs_ncyl % sblock.fs_cpg)
		sblock.fs_ncg++;
	sblock.fs_dblkno = sblock.fs_iblkno + sblock.fs_ipg / INOPF(&sblock);
	i = MIN(~sblock.fs_cgmask, sblock.fs_ncg - 1);
	if (cgdmin(&sblock, i) - cgbase(&sblock, i) >= sblock.fs_fpg) {
		printf("inode blocks/cyl group (%d) >= data blocks (%d)\n",
		    cgdmin(&sblock, i) - cgbase(&sblock, i) / sblock.fs_frag,
		    sblock.fs_fpg / sblock.fs_frag);
		printf("number of cylinders per cylinder group (%d) %s.\n",
		    sblock.fs_cpg, "must be increased");
		exit(1);
	}
	j = sblock.fs_ncg - 1;
	if ((i = fssize - j * sblock.fs_fpg) < sblock.fs_fpg &&
	    cgdmin(&sblock, j) - cgbase(&sblock, j) > i) {
		printf("Warning: inode blocks/cyl group (%d) >= data blocks (%d) in last\n",
		    (cgdmin(&sblock, j) - cgbase(&sblock, j)) / sblock.fs_frag,
		    i / sblock.fs_frag);
		printf("    cylinder group. This implies %d sector(s) cannot be allocated.\n",
		    i * NSPF(&sblock));
		sblock.fs_ncg--;
		sblock.fs_ncyl -= sblock.fs_ncyl % sblock.fs_cpg;
		sblock.fs_size = fssize = sblock.fs_ncyl * sblock.fs_spc /
		    NSPF(&sblock);
		warn = 0;
	}
	if (warn) {
		printf("Warning: %d sector(s) in last cylinder unallocated\n",
		    sblock.fs_spc -
		    (fssize * NSPF(&sblock) - (sblock.fs_ncyl - 1)
		    * sblock.fs_spc));
	}
	/*
	 * fill in remaining fields of the super block
	 */
	sblock.fs_csaddr = cgdmin(&sblock, 0);
	sblock.fs_cssize =
	    fragroundup(&sblock, sblock.fs_ncg * sizeof(struct csum));
	i = sblock.fs_bsize / sizeof(struct csum);
	sblock.fs_csmask = ~(i - 1);
	for (sblock.fs_csshift = 0; i > 1; i >>= 1)
		sblock.fs_csshift++;
	fscs = (struct csum *)calloc(1, sblock.fs_cssize);
	sblock.fs_magic = FS_MAGIC;
	sblock.fs_rotdelay = rotdelay;
	sblock.fs_minfree = minfree;
	sblock.fs_maxcontig = maxcontig;
	sblock.fs_headswitch = headswitch;
	sblock.fs_trkseek = trackseek;
	sblock.fs_maxbpg = maxbpg;
	sblock.fs_rps = rpm / 60;
	sblock.fs_optim = opt;
	sblock.fs_cgrotor = 0;
	sblock.fs_cstotal.cs_ndir = 0;
	sblock.fs_cstotal.cs_nbfree = 0;
	sblock.fs_cstotal.cs_nifree = 0;
	sblock.fs_cstotal.cs_nffree = 0;
	sblock.fs_fmod = 0;
	sblock.fs_ronly = 0;
	/*
	 * Dump out summary information about file system.
	 */
	printf("%s:\t%d sectors in %d cylinders of %d tracks, %d sectors\n",
	    fsys, sblock.fs_size * NSPF(&sblock), sblock.fs_ncyl,
	    sblock.fs_ntrak, sblock.fs_nsect);
	printf("\t%.1fMb in %d cyl groups (%d c/g, %.2fMb/g, %d i/g)\n",
	    (float)sblock.fs_size * sblock.fs_fsize * 1e-6, sblock.fs_ncg,
	    sblock.fs_cpg, (float)sblock.fs_fpg * sblock.fs_fsize * 1e-6,
	    sblock.fs_ipg);
	/*
	 * Now build the cylinders group blocks and
	 * then print out indices of cylinder groups.
	 */
	printf("super-block backups (for fsck -b #) at:");
	for (cylno = 0; cylno < sblock.fs_ncg; cylno++) {
		initcg(cylno);
		if (cylno % 9 == 0)
			printf("\n");
		printf(" %d,", fsbtodb(&sblock, cgsblock(&sblock, cylno)));
	}
	printf("\n");
	if (Nflag)
		exit(0);
	/*
	 * Now construct the initial file system,
	 * then write out the super-block.
	 */
	fsinit();
	sblock.fs_time = utime;
	wtfs(SBOFF / sectorsize, sbsize, (char *)&sblock);
	for (i = 0; i < sblock.fs_cssize; i += sblock.fs_bsize)
		wtfs(fsbtodb(&sblock, sblock.fs_csaddr + numfrags(&sblock, i)),
			sblock.fs_cssize - i < sblock.fs_bsize ?
			    sblock.fs_cssize - i : sblock.fs_bsize,
			((char *)fscs) + i);
	/* 
	 * Write out the duplicate super blocks
	 */
	for (cylno = 0; cylno < sblock.fs_ncg; cylno++)
		wtfs(fsbtodb(&sblock, cgsblock(&sblock, cylno)),
		    sbsize, (char *)&sblock);
	/*
	 * Update information about this partion in pack
	 * label, to that it may be updated on disk.
	 */
	pp->p_fstype = FS_BSDFFS;
	pp->p_fsize = sblock.fs_fsize;
	pp->p_frag = sblock.fs_frag;
	pp->p_cpg = sblock.fs_cpg;
}

/*
 * Initialize a cylinder group.
 */
initcg(cylno)
	int cylno;
{
	daddr_t cbase, d, dlower, dupper, dmax;
	long i, j, s;
	register struct csum *cs;

	/*
	 * Determine block bounds for cylinder group.
	 * Allow space for super block summary information in first
	 * cylinder group.
	 */
	cbase = cgbase(&sblock, cylno);
	dmax = cbase + sblock.fs_fpg;
	if (dmax > sblock.fs_size)
		dmax = sblock.fs_size;
	dlower = cgsblock(&sblock, cylno) - cbase;
	dupper = cgdmin(&sblock, cylno) - cbase;
	if (cylno == 0)
		dupper += howmany(sblock.fs_cssize, sblock.fs_fsize);
	cs = fscs + cylno;
	acg.cg_time = utime;
	acg.cg_magic = CG_MAGIC;
	acg.cg_cgx = cylno;
	if (cylno == sblock.fs_ncg - 1)
		acg.cg_ncyl = sblock.fs_ncyl % sblock.fs_cpg;
	else
		acg.cg_ncyl = sblock.fs_cpg;
	acg.cg_niblk = sblock.fs_ipg;
	acg.cg_ndblk = dmax - cbase;
	acg.cg_cs.cs_ndir = 0;
	acg.cg_cs.cs_nffree = 0;
	acg.cg_cs.cs_nbfree = 0;
	acg.cg_cs.cs_nifree = 0;
	acg.cg_rotor = 0;
	acg.cg_frotor = 0;
	acg.cg_irotor = 0;
	acg.cg_btotoff = &acg.cg_space[0] - (u_char *)(&acg.cg_link);
	acg.cg_boff = acg.cg_btotoff + sblock.fs_cpg * sizeof(long);
	acg.cg_iusedoff = acg.cg_boff + 
		sblock.fs_cpg * sblock.fs_nrpos * sizeof(short);
	acg.cg_freeoff = acg.cg_iusedoff + howmany(sblock.fs_ipg, NBBY);
	acg.cg_nextfreeoff = acg.cg_freeoff +
		howmany(sblock.fs_cpg * sblock.fs_spc / NSPF(&sblock), NBBY);
	for (i = 0; i < sblock.fs_frag; i++) {
		acg.cg_frsum[i] = 0;
	}
	bzero((caddr_t)cg_inosused(&acg), acg.cg_freeoff - acg.cg_iusedoff);
	acg.cg_cs.cs_nifree += sblock.fs_ipg;
	if (cylno == 0)
		for (i = 0; i < ROOTINO; i++) {
			setbit(cg_inosused(&acg), i);
			acg.cg_cs.cs_nifree--;
		}
	for (i = 0; i < sblock.fs_ipg / INOPF(&sblock); i += sblock.fs_frag)
		wtfs(fsbtodb(&sblock, cgimin(&sblock, cylno) + i),
		    sblock.fs_bsize, (char *)zino);
	bzero((caddr_t)cg_blktot(&acg), acg.cg_boff - acg.cg_btotoff);
	bzero((caddr_t)cg_blks(&sblock, &acg, 0),
	    acg.cg_iusedoff - acg.cg_boff);
	bzero((caddr_t)cg_blksfree(&acg), acg.cg_nextfreeoff - acg.cg_freeoff);
	if (cylno > 0) {
		/*
		 * In cylno 0, beginning space is reserved
		 * for boot and super blocks.
		 */
		for (d = 0; d < dlower; d += sblock.fs_frag) {
			setblock(&sblock, cg_blksfree(&acg), d/sblock.fs_frag);
			acg.cg_cs.cs_nbfree++;
			cg_blktot(&acg)[cbtocylno(&sblock, d)]++;
			cg_blks(&sblock, &acg, cbtocylno(&sblock, d))
			    [cbtorpos(&sblock, d)]++;
		}
		sblock.fs_dsize += dlower;
	}
	sblock.fs_dsize += acg.cg_ndblk - dupper;
	if (i = dupper % sblock.fs_frag) {
		acg.cg_frsum[sblock.fs_frag - i]++;
		for (d = dupper + sblock.fs_frag - i; dupper < d; dupper++) {
			setbit(cg_blksfree(&acg), dupper);
			acg.cg_cs.cs_nffree++;
		}
	}
	for (d = dupper; d + sblock.fs_frag <= dmax - cbase; ) {
		setblock(&sblock, cg_blksfree(&acg), d / sblock.fs_frag);
		acg.cg_cs.cs_nbfree++;
		cg_blktot(&acg)[cbtocylno(&sblock, d)]++;
		cg_blks(&sblock, &acg, cbtocylno(&sblock, d))
		    [cbtorpos(&sblock, d)]++;
		d += sblock.fs_frag;
	}
	if (d < dmax - cbase) {
		acg.cg_frsum[dmax - cbase - d]++;
		for (; d < dmax - cbase; d++) {
			setbit(cg_blksfree(&acg), d);
			acg.cg_cs.cs_nffree++;
		}
	}
	sblock.fs_cstotal.cs_ndir += acg.cg_cs.cs_ndir;
	sblock.fs_cstotal.cs_nffree += acg.cg_cs.cs_nffree;
	sblock.fs_cstotal.cs_nbfree += acg.cg_cs.cs_nbfree;
	sblock.fs_cstotal.cs_nifree += acg.cg_cs.cs_nifree;
	*cs = acg.cg_cs;
	wtfs(fsbtodb(&sblock, cgtod(&sblock, cylno)),
		sblock.fs_bsize, (char *)&acg);
}

/*
 * initialize the file system
 */
struct inode node;

#ifdef LOSTDIR
#define PREDEFDIR 3
#else
#define PREDEFDIR 2
#endif

struct direct root_dir[] = {
	{ ROOTINO, sizeof(struct direct), 1, "." },
	{ ROOTINO, sizeof(struct direct), 2, ".." },
#ifdef LOSTDIR
	{ LOSTFOUNDINO, sizeof(struct direct), 10, "lost+found" },
#endif
};
#ifdef LOSTDIR
struct direct lost_found_dir[] = {
	{ LOSTFOUNDINO, sizeof(struct direct), 1, "." },
	{ ROOTINO, sizeof(struct direct), 2, ".." },
	{ 0, DIRBLKSIZ, 0, 0 },
};
#endif
char buf[MAXBSIZE];

fsinit()
{
	int i;

	/*
	 * initialize the node
	 */
	node.i_atime = utime;
	node.i_mtime = utime;
	node.i_ctime = utime;
#ifdef LOSTDIR
	/*
	 * create the lost+found directory
	 */
	(void)makedir(lost_found_dir, 2);
	for (i = DIRBLKSIZ; i < sblock.fs_bsize; i += DIRBLKSIZ)
		bcopy(&lost_found_dir[2], &buf[i], DIRSIZ(&lost_found_dir[2]));
	node.i_number = LOSTFOUNDINO;
	node.i_mode = IFDIR | UMASK;
	node.i_nlink = 2;
	node.i_size = sblock.fs_bsize;
	node.i_db[0] = alloc(node.i_size, node.i_mode);
	node.i_blocks = btodb(fragroundup(&sblock, node.i_size));
	wtfs(fsbtodb(&sblock, node.i_db[0]), node.i_size, buf);
	iput(&node);
#endif
	/*
	 * create the root directory
	 */
	node.i_number = ROOTINO;
	node.i_mode = IFDIR | UMASK;
	node.i_nlink = PREDEFDIR;
	node.i_size = makedir(root_dir, PREDEFDIR);
	node.i_db[0] = alloc(sblock.fs_fsize, node.i_mode);
	node.i_blocks = btodb(fragroundup(&sblock, node.i_size));
	wtfs(fsbtodb(&sblock, node.i_db[0]), sblock.fs_fsize, buf);
	iput(&node);
}

/*
 * construct a set of directory entries in "buf".
 * return size of directory.
 */
makedir(protodir, entries)
	register struct direct *protodir;
	int entries;
{
	char *cp;
	int i, spcleft;

	spcleft = DIRBLKSIZ;
	for (cp = buf, i = 0; i < entries - 1; i++) {
		protodir[i].d_reclen = DIRSIZ(&protodir[i]);
		bcopy(&protodir[i], cp, protodir[i].d_reclen);
		cp += protodir[i].d_reclen;
		spcleft -= protodir[i].d_reclen;
	}
	protodir[i].d_reclen = spcleft;
	bcopy(&protodir[i], cp, DIRSIZ(&protodir[i]));
	return (DIRBLKSIZ);
}

/*
 * allocate a block or frag
 */
daddr_t
alloc(size, mode)
	int size;
	int mode;
{
	int i, frag;
	daddr_t d;

	rdfs(fsbtodb(&sblock, cgtod(&sblock, 0)), sblock.fs_cgsize,
	    (char *)&acg);
	if (acg.cg_magic != CG_MAGIC) {
		printf("cg 0: bad magic number\n");
		return (0);
	}
	if (acg.cg_cs.cs_nbfree == 0) {
		printf("first cylinder group ran out of space\n");
		return (0);
	}
	for (d = 0; d < acg.cg_ndblk; d += sblock.fs_frag)
		if (isblock(&sblock, cg_blksfree(&acg), d / sblock.fs_frag))
			goto goth;
	printf("internal error: can't find block in cyl 0\n");
	return (0);
goth:
	clrblock(&sblock, cg_blksfree(&acg), d / sblock.fs_frag);
	acg.cg_cs.cs_nbfree--;
	sblock.fs_cstotal.cs_nbfree--;
	fscs[0].cs_nbfree--;
	if (mode & IFDIR) {
		acg.cg_cs.cs_ndir++;
		sblock.fs_cstotal.cs_ndir++;
		fscs[0].cs_ndir++;
	}
	cg_blktot(&acg)[cbtocylno(&sblock, d)]--;
	cg_blks(&sblock, &acg, cbtocylno(&sblock, d))[cbtorpos(&sblock, d)]--;
	if (size != sblock.fs_bsize) {
		frag = howmany(size, sblock.fs_fsize);
		fscs[0].cs_nffree += sblock.fs_frag - frag;
		sblock.fs_cstotal.cs_nffree += sblock.fs_frag - frag;
		acg.cg_cs.cs_nffree += sblock.fs_frag - frag;
		acg.cg_frsum[sblock.fs_frag - frag]++;
		for (i = frag; i < sblock.fs_frag; i++)
			setbit(cg_blksfree(&acg), d + i);
	}
	wtfs(fsbtodb(&sblock, cgtod(&sblock, 0)), sblock.fs_cgsize,
	    (char *)&acg);
	return (d);
}

/*
 * Allocate an inode on the disk
 */
iput(ip)
	register struct inode *ip;
{
	struct dinode buf[MAXINOPB];
	daddr_t d;
	int c;

	c = itog(&sblock, ip->i_number);
	rdfs(fsbtodb(&sblock, cgtod(&sblock, 0)), sblock.fs_cgsize,
	    (char *)&acg);
	if (acg.cg_magic != CG_MAGIC) {
		printf("cg 0: bad magic number\n");
		exit(1);
	}
	acg.cg_cs.cs_nifree--;
	setbit(cg_inosused(&acg), ip->i_number);
	wtfs(fsbtodb(&sblock, cgtod(&sblock, 0)), sblock.fs_cgsize,
	    (char *)&acg);
	sblock.fs_cstotal.cs_nifree--;
	fscs[0].cs_nifree--;
	if (ip->i_number >= sblock.fs_ipg * sblock.fs_ncg) {
		printf("fsinit: inode value out of range (%d).\n",
		    ip->i_number);
		exit(1);
	}
	d = fsbtodb(&sblock, itod(&sblock, ip->i_number));
	rdfs(d, sblock.fs_bsize, buf);
	buf[itoo(&sblock, ip->i_number)].di_ic = ip->i_ic;
	wtfs(d, sblock.fs_bsize, buf);
}

/*
 * read a block from the file system
 */
rdfs(bno, size, bf)
	daddr_t bno;
	int size;
	char *bf;
{
	int n;

	if (lseek(fsi, bno * sectorsize, 0) < 0) {
		printf("seek error: %ld\n", bno);
		perror("rdfs");
		exit(1);
	}
	n = read(fsi, bf, size);
	if(n != size) {
		printf("read error: %ld\n", bno);
		perror("rdfs");
		exit(1);
	}
}

/*
 * write a block to the file system
 */
wtfs(bno, size, bf)
	daddr_t bno;
	int size;
	char *bf;
{
	int n;

	if (Nflag)
		return;
	if (lseek(fso, bno * sectorsize, 0) < 0) {
		printf("seek error: %ld\n", bno);
		perror("wtfs");
		exit(1);
	}
	n = write(fso, bf, size);
	if(n != size) {
		printf("write error: %D\n", bno);
		perror("wtfs");
		exit(1);
	}
}

/*
 * check if a block is available
 */
isblock(fs, cp, h)
	struct fs *fs;
	unsigned char *cp;
	int h;
{
	unsigned char mask;

	switch (fs->fs_frag) {
	case 8:
		return (cp[h] == 0xff);
	case 4:
		mask = 0x0f << ((h & 0x1) << 2);
		return ((cp[h >> 1] & mask) == mask);
	case 2:
		mask = 0x03 << ((h & 0x3) << 1);
		return ((cp[h >> 2] & mask) == mask);
	case 1:
		mask = 0x01 << (h & 0x7);
		return ((cp[h >> 3] & mask) == mask);
	default:
#ifdef STANDALONE
		printf("isblock bad fs_frag %d\n", fs->fs_frag);
#else
		fprintf(stderr, "isblock bad fs_frag %d\n", fs->fs_frag);
#endif
		return (0);
	}
}

/*
 * take a block out of the map
 */
clrblock(fs, cp, h)
	struct fs *fs;
	unsigned char *cp;
	int h;
{
	switch ((fs)->fs_frag) {
	case 8:
		cp[h] = 0;
		return;
	case 4:
		cp[h >> 1] &= ~(0x0f << ((h & 0x1) << 2));
		return;
	case 2:
		cp[h >> 2] &= ~(0x03 << ((h & 0x3) << 1));
		return;
	case 1:
		cp[h >> 3] &= ~(0x01 << (h & 0x7));
		return;
	default:
#ifdef STANDALONE
		printf("clrblock bad fs_frag %d\n", fs->fs_frag);
#else
		fprintf(stderr, "clrblock bad fs_frag %d\n", fs->fs_frag);
#endif
		return;
	}
}

/*
 * put a block into the map
 */
setblock(fs, cp, h)
	struct fs *fs;
	unsigned char *cp;
	int h;
{
	switch (fs->fs_frag) {
	case 8:
		cp[h] = 0xff;
		return;
	case 4:
		cp[h >> 1] |= (0x0f << ((h & 0x1) << 2));
		return;
	case 2:
		cp[h >> 2] |= (0x03 << ((h & 0x3) << 1));
		return;
	case 1:
		cp[h >> 3] |= (0x01 << (h & 0x7));
		return;
	default:
#ifdef STANDALONE
		printf("setblock bad fs_frag %d\n", fs->fs_frag);
#else
		fprintf(stderr, "setblock bad fs_frag %d\n", fs->fs_frag);
#endif
		return;
	}
}