Source to arch/i386/i386/disksubr.c


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/*
 * Copyright (c) 1982, 1986, 1988 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.
 *
 *	from: @(#)ufs_disksubr.c	7.16 (Berkeley) 5/4/91
 *	disksubr.c,v 1.2 1993/05/22 07:59:47 cgd Exp
 */

#include "param.h"
#include "systm.h"
#include "buf.h"
#include "dkbad.h"
#include "disklabel.h"
#include "syslog.h"

/* encoding of disk minor numbers, should be elsewhere... */
#define dkunit(dev)		(minor(dev) >> 3)
#define dkpart(dev)		(minor(dev) & 7)
#define dkminor(unit, part)	(((unit) << 3) | (part))

#define	b_cylin	b_resid

/*
 * Attempt to read a disk label from a device
 * using the indicated stategy routine.
 * The label must be partly set up before this:
 * secpercyl, secsize and anything required for a block i/o read
 * operation in the driver's strategy/start routines
 * must be filled in before calling us.
 *
 * If dos partition table requested, attempt to load it and
 * find disklabel inside a DOS partition. Also, if bad block
 * table needed, attempt to extract it as well. Return buffer
 * for use in signalling errors if requested.
 *
 * Returns null on success and an error string on failure.
 */
char *
cpu_readdisklabel(dev, strat, lp, osdep)
	dev_t dev;
	int (*strat)();
	register struct disklabel *lp;
	struct cpu_disklabel *osdep;
{
	struct dos_partition *dp = osdep->dosparts;
	struct dkbad *bdp = &osdep->bad;
	register struct buf *bp;
	struct disklabel *dlp;
	char *msg = NULL;
	int cyl, dospartoff, i;

	/* minimal requirements for archtypal disk label */
	if (lp->d_secperunit == 0)
		lp->d_secperunit = 0x1fffffff;
	lp->d_npartitions = 1;
	if (lp->d_partitions[0].p_size == 0)
		lp->d_partitions[0].p_size = 0x1fffffff;
	lp->d_partitions[0].p_offset = 0;

	/* obtain buffer to probe drive with */
	bp = geteblk((int)lp->d_secsize);
	
	/* request no partition relocation by driver on I/O operations */
	bp->b_dev = makedev(major(dev), dkminor((dkunit(dev)), 3));

	/* do dos partitions in the process of getting disklabel? */
	dospartoff = 0;
	cyl = LABELSECTOR / lp->d_secpercyl;
	if (dp) {
		struct dos_partition *ap;

		/* read master boot record */
		bp->b_blkno = DOSBBSECTOR;
		bp->b_bcount = lp->d_secsize;
		bp->b_flags = B_BUSY | B_READ;
		bp->b_cylin = DOSBBSECTOR / lp->d_secpercyl;
		(*strat)(bp);

		/* if successful, wander through dos partition table */
		if (biowait(bp)) {
			msg = "dos partition I/O error";
			goto done;
		} else {
			/* XXX how do we check veracity/bounds of this? */
			bcopy(bp->b_un.b_addr + DOSPARTOFF, dp,
				NDOSPART * sizeof(*dp));
			for (i = 0; i < NDOSPART; i++, dp++)
				/* is this ours? */
				if (dp->dp_size &&
					dp->dp_typ == DOSPTYP_386BSD
					&& dospartoff == 0) {

					/* need sector address for SCSI/IDE,
					   cylinder for ESDI/ST506/RLL */
					dospartoff = dp->dp_start;
					cyl = DPCYL(dp->dp_scyl, dp->dp_ssect);

					/* update disklabel with details */
					lp->d_partitions[0].p_size =
						dp->dp_size;
					lp->d_partitions[0].p_offset = 
						dp->dp_start;
					lp->d_ntracks = dp->dp_ehd + 1;
					lp->d_nsectors = DPSECT(dp->dp_esect);
					lp->d_subtype |= (lp->d_subtype & 3)
							+ i | DSTYPE_INDOSPART;
					lp->d_secpercyl = lp->d_ntracks *
						lp->d_nsectors;
				}
		}
			
	}
	
	/* next, dig out disk label */
	bp->b_blkno = dospartoff + LABELSECTOR;
	bp->b_cylin = cyl;
	bp->b_bcount = lp->d_secsize;
	bp->b_flags = B_BUSY | B_READ;
	(*strat)(bp);

	/* if successful, locate disk label within block and validate */
	if (biowait(bp)) {
		msg = "disk label I/O error";
		goto done;
	} else for (dlp = (struct disklabel *)bp->b_un.b_addr;
	    dlp <= (struct disklabel *)(bp->b_un.b_addr+DEV_BSIZE-sizeof(*dlp));
	    dlp = (struct disklabel *)((char *)dlp + sizeof(long))) {
		if (dlp->d_magic != DISKMAGIC || dlp->d_magic2 != DISKMAGIC) {
			if (msg == NULL)
				msg = "no disk label";
		} else if (dlp->d_npartitions > MAXPARTITIONS ||
			   dkcksum(dlp) != 0)
			msg = "disk label corrupted";
		else {
			*lp = *dlp;
			msg = NULL;
			break;
		}
	}

	if (msg)
		goto done;

	/* obtain bad sector table if requested and present */
	if (bdp && (lp->d_flags & D_BADSECT)) {
		struct dkbad *db;

		i = 0;
		do {
			/* read a bad sector table */
			bp->b_flags = B_BUSY | B_READ;
			bp->b_blkno = lp->d_secperunit - lp->d_nsectors + i;
			if (lp->d_secsize > DEV_BSIZE)
				bp->b_blkno *= lp->d_secsize / DEV_BSIZE;
			else
				bp->b_blkno /= DEV_BSIZE / lp->d_secsize;
			bp->b_bcount = lp->d_secsize;
			bp->b_cylin = lp->d_ncylinders - 1;
			(*strat)(bp);

			/* if successful, validate, otherwise try another */
			if (biowait(bp)) {
				msg = "bad sector table I/O error";
			} else {
				db = (struct dkbad *)(bp->b_un.b_addr);
#define DKBAD_MAGIC 0x4321
				if (db->bt_mbz == 0
					&& db->bt_flag == DKBAD_MAGIC) {
					msg = NULL;
					*bdp = *db;
					break;
				} else
					msg = "bad sector table corrupted";
			}
		} while ((bp->b_flags & B_ERROR) && (i += 2) < 10 &&
			i < lp->d_nsectors);
	}

done:
	bp->b_flags = B_INVAL | B_AGE | B_READ;
	brelse(bp);
	return (msg);
}

/*
 * Check new disk label for sensibility
 * before setting it.
 */
cpu_setdisklabel(olp, nlp, openmask, osdep)
	register struct disklabel *olp, *nlp;
	u_long openmask;
	struct cpu_disklabel *osdep;
{
	struct dos_partition *dp = osdep->dosparts;
	register i;
	register struct partition *opp, *npp;

	/* sanity clause */
	if (nlp->d_secpercyl == 0 || nlp->d_secsize == 0
		|| (nlp->d_secsize % DEV_BSIZE) != 0)
			return(EINVAL);

	/* special case to allow disklabel to be invalidated */
	if (nlp->d_magic == 0xffffffff) {
		*olp = *nlp;
		return (0);
	}

	if (nlp->d_magic != DISKMAGIC || nlp->d_magic2 != DISKMAGIC ||
	    dkcksum(nlp) != 0)
		return (EINVAL);

	/* XXX missing check if other dos partitions will be overwritten */

	while ((i = ffs((long)openmask)) != 0) {
		i--;
		openmask &= ~(1 << i);
		if (nlp->d_npartitions <= i)
			return (EBUSY);
		opp = &olp->d_partitions[i];
		npp = &nlp->d_partitions[i];
		if (npp->p_offset != opp->p_offset || npp->p_size < opp->p_size)
			return (EBUSY);
		/*
		 * Copy internally-set partition information
		 * if new label doesn't include it.		XXX
		 */
		if (npp->p_fstype == FS_UNUSED && opp->p_fstype != FS_UNUSED) {
			npp->p_fstype = opp->p_fstype;
			npp->p_fsize = opp->p_fsize;
			npp->p_frag = opp->p_frag;
			npp->p_cpg = opp->p_cpg;
		}
	}
 	nlp->d_checksum = 0;
 	nlp->d_checksum = dkcksum(nlp);
	*olp = *nlp;
	return (0);
}


/*
 * Write disk label back to device after modification.
 */
cpu_writedisklabel(dev, strat, lp, osdep)
	dev_t dev;
	int (*strat)();
	register struct disklabel *lp;
	struct cpu_disklabel *osdep;
{
	struct dos_partition *dp = osdep->dosparts;
	struct buf *bp;
	struct disklabel *dlp;
	int labelpart, error = 0, dospartoff, cyl, i;

	labelpart = dkpart(dev);
#ifdef nope
	if (lp->d_partitions[labelpart].p_offset != 0) {
		if (lp->d_partitions[0].p_offset != 0)
			return (EXDEV);			/* not quite right */
		labelpart = 0;
	}
#else
		labelpart = 3;
#endif

	bp = geteblk((int)lp->d_secsize);
	/* request no partition relocation by driver on I/O operations */
	bp->b_dev = makedev(major(dev), dkminor((dkunit(dev)), 3));

	/* do dos partitions in the process of getting disklabel? */
	dospartoff = 0;
	cyl = LABELSECTOR / lp->d_secpercyl;
	if (dp) {
		bp->b_blkno = DOSBBSECTOR;
		bp->b_bcount = lp->d_secsize;
		bp->b_flags = B_BUSY | B_READ;
		bp->b_cylin = DOSBBSECTOR / lp->d_secpercyl;
		(*strat)(bp);
		if ((error = biowait(bp)) == 0) {
			bcopy(bp->b_un.b_addr + DOSPARTOFF, dp,
				NDOSPART * sizeof(*dp));
			for (i = 0; i < NDOSPART; i++, dp++)
				if(dp->dp_size && dp->dp_typ == DOSPTYP_386BSD
					&& dospartoff == 0) {
					/* need sector address for SCSI/IDE,
					   cylinder for ESDI/ST506/RLL */
					dospartoff = dp->dp_start;
					cyl = dp->dp_scyl |
						((dp->dp_ssect & 0xc0) << 2);
				}
		}
			
	}
	
#ifdef maybe
	/* disklabel in appropriate location? */
	if (lp->d_partitions[0].p_offset != 0
		&& lp->d_partitions[0].p_offset != dospartoff) {
		error = EXDEV;		
		goto done;
	}
#endif

	bp->b_blkno = dospartoff + LABELSECTOR;
	bp->b_cylin = cyl;
	bp->b_bcount = lp->d_secsize;
	bp->b_flags = B_READ;
	(*strat)(bp);
	if (error = biowait(bp))
		goto done;
	for (dlp = (struct disklabel *)bp->b_un.b_addr;
	    dlp <= (struct disklabel *)
	      (bp->b_un.b_addr + lp->d_secsize - sizeof(*dlp));
	    dlp = (struct disklabel *)((char *)dlp + sizeof(long))) {
		if (dlp->d_magic == DISKMAGIC && dlp->d_magic2 == DISKMAGIC &&
		    dkcksum(dlp) == 0) {
			*dlp = *lp;
			bp->b_flags = B_WRITE;
			(*strat)(bp);
			error = biowait(bp);
			goto done;
		}
	}
	error = ESRCH;
done:
	brelse(bp);
	return (error);
}

/*
 * Determine the size of the transfer, and make sure it is
 * within the boundaries of the partition. Adjust transfer
 * if needed, and signal errors or early completion.
 */
int
bounds_check_with_label(struct buf *bp, struct disklabel *lp, int wlabel)
{
	struct partition *p = lp->d_partitions + dkpart(bp->b_dev);
	int labelsect = lp->d_partitions[0].p_offset;
	int maxsz = p->p_size,
		sz = (bp->b_bcount + DEV_BSIZE - 1) >> DEV_BSHIFT;

	/* overwriting disk label ? */
	/* XXX should also protect bootstrap in first 8K */
        if (bp->b_blkno + p->p_offset <= LABELSECTOR + labelsect &&
#if LABELSECTOR != 0
            bp->b_blkno + p->p_offset + sz > LABELSECTOR + labelsect &&
#endif
            (bp->b_flags & B_READ) == 0 && wlabel == 0) {
                bp->b_error = EROFS;
                goto bad;
        }

#if	defined(DOSBBSECTOR) && defined(notyet)
	/* overwriting master boot record? */
        if (bp->b_blkno + p->p_offset <= DOSBBSECTOR &&
            (bp->b_flags & B_READ) == 0 && wlabel == 0) {
                bp->b_error = EROFS;
                goto bad;
        }
#endif

	/* beyond partition? */
        if (bp->b_blkno < 0 || bp->b_blkno + sz > maxsz) {
                /* if exactly at end of disk, return an EOF */
                if (bp->b_blkno == maxsz) {
                        bp->b_resid = bp->b_bcount;
                        return(0);
                }
                /* or truncate if part of it fits */
                sz = maxsz - bp->b_blkno;
                if (sz <= 0) {
			bp->b_error = EINVAL;
                        goto bad;
		}
                bp->b_bcount = sz << DEV_BSHIFT;
        }

	/* calculate cylinder for disksort to order transfers with */
        bp->b_cylin = (bp->b_blkno + p->p_offset) / lp->d_secpercyl;
	return(1);

bad:
	bp->b_flags |= B_ERROR;
	return(-1);
}