Source to ufs/ufs_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
 *	ufs_disksubr.c,v 1.3 1993/05/20 23:16:51 deraadt Exp
 */

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

/*
 * Seek sort for disks.  We depend on the driver
 * which calls us using b_resid as the current cylinder number.
 *
 * The argument dp structure holds a b_actf activity chain pointer
 * on which we keep two queues, sorted in ascending cylinder order.
 * The first queue holds those requests which are positioned after
 * the current cylinder (in the first request); the second holds
 * requests which came in after their cylinder number was passed.
 * Thus we implement a one way scan, retracting after reaching the
 * end of the drive to the first request on the second queue,
 * at which time it becomes the first queue.
 *
 * A one-way scan is natural because of the way UNIX read-ahead
 * blocks are allocated.
 */

#define	b_cylin	b_resid

void
disksort(dp, bp)
	register struct buf *dp, *bp;
{
	register struct buf *ap;

	/*
	 * If nothing on the activity queue, then
	 * we become the only thing.
	 */
	ap = dp->b_actf;
	if(ap == NULL) {
		dp->b_actf = bp;
		dp->b_actl = bp;
		bp->av_forw = NULL;
		return;
	}
	/*
	 * If we lie after the first (currently active)
	 * request, then we must locate the second request list
	 * and add ourselves to it.
	 */
	if (bp->b_cylin < ap->b_cylin) {
		while (ap->av_forw) {
			/*
			 * Check for an ``inversion'' in the
			 * normally ascending cylinder numbers,
			 * indicating the start of the second request list.
			 */
			if (ap->av_forw->b_cylin < ap->b_cylin) {
				/*
				 * Search the second request list
				 * for the first request at a larger
				 * cylinder number.  We go before that;
				 * if there is no such request, we go at end.
				 */
				do {
					if (bp->b_cylin < ap->av_forw->b_cylin)
						goto insert;
					if (bp->b_cylin == ap->av_forw->b_cylin &&
					    bp->b_blkno < ap->av_forw->b_blkno)
						goto insert;
					ap = ap->av_forw;
				} while (ap->av_forw);
				goto insert;		/* after last */
			}
			ap = ap->av_forw;
		}
		/*
		 * No inversions... we will go after the last, and
		 * be the first request in the second request list.
		 */
		goto insert;
	}
	/*
	 * Request is at/after the current request...
	 * sort in the first request list.
	 */
	while (ap->av_forw) {
		/*
		 * We want to go after the current request
		 * if there is an inversion after it (i.e. it is
		 * the end of the first request list), or if
		 * the next request is a larger cylinder than our request.
		 */
		if (ap->av_forw->b_cylin < ap->b_cylin ||
		    bp->b_cylin < ap->av_forw->b_cylin ||
		    (bp->b_cylin == ap->av_forw->b_cylin &&
		    bp->b_blkno < ap->av_forw->b_blkno))
			goto insert;
		ap = ap->av_forw;
	}
	/*
	 * Neither a second list nor a larger
	 * request... we go at the end of the first list,
	 * which is the same as the end of the whole schebang.
	 */
insert:
	bp->av_forw = ap->av_forw;
	ap->av_forw = bp;
	if (ap == dp->b_actl)
		dp->b_actl = bp;
}

/* 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))

/*
 * 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.
 *
 * Returns null on success and an error string on failure.
 */
char *
readdisklabel(dev, strat, lp, osdep)
	dev_t dev;
	int (*strat)();
	register struct disklabel *lp;
	struct cpu_disklabel *osdep;
{
	return cpu_readdisklabel(dev, strat, lp, osdep);
}


/*
 * Check new disk label for sensibility
 * before setting it.
 */
setdisklabel(olp, nlp, openmask, osdep)
	register struct disklabel *olp, *nlp;
	u_long openmask;
	struct cpu_disklabel *osdep;
{
	return cpu_setdisklabel(olp, nlp, openmask, osdep);
}


/*
 * Write disk label back to device after modification.
 */
writedisklabel(dev, strat, lp, osdep)
	dev_t dev;
	int (*strat)();
	register struct disklabel *lp;
	struct cpu_disklabel *osdep;
{
	return cpu_writedisklabel(dev, strat, lp, osdep);
}

/*
 * Compute checksum for disk label.
 */
dkcksum(lp)
	register struct disklabel *lp;
{
	register u_short *start, *end;
	register u_short sum = 0;

	start = (u_short *)lp;
	end = (u_short *)&lp->d_partitions[lp->d_npartitions];
	while (start < end)
		sum ^= *start++;
	return (sum);
}

/*
 * Disk error is the preface to plaintive error messages
 * about failing disk transfers.  It prints messages of the form

hp0g: hard error reading fsbn 12345 of 12344-12347 (hp0 bn %d cn %d tn %d sn %d)

 * if the offset of the error in the transfer and a disk label
 * are both available.  blkdone should be -1 if the position of the error
 * is unknown; the disklabel pointer may be null from drivers that have not
 * been converted to use them.  The message is printed with printf
 * if pri is LOG_PRINTF, otherwise it uses log at the specified priority.
 * The message should be completed (with at least a newline) with printf
 * or addlog, respectively.  There is no trailing space.
 */
void
diskerr(bp, dname, what, pri, blkdone, lp)
	register struct buf *bp;
	char *dname, *what;
	int pri, blkdone;
	register struct disklabel *lp;
{
	int unit = dkunit(bp->b_dev), part = dkpart(bp->b_dev);
	register void (*pr) __P((const char *, ...));
	char partname = 'a' + part;
	int sn;

	if (pri != LOG_PRINTF) {
		log(pri, "");
		pr = addlog;
	} else
		pr = printf;
	(*pr)("%s%d%c: %s %sing fsbn ", dname, unit, partname, what,
	    bp->b_flags & B_READ ? "read" : "writ");
	sn = bp->b_blkno;
	if (bp->b_bcount <= DEV_BSIZE)
		(*pr)("%d", sn);
	else {
		if (blkdone >= 0) {
			sn += blkdone;
			(*pr)("%d of ", sn);
		}
		(*pr)("%d-%d", bp->b_blkno,
		    bp->b_blkno + (bp->b_bcount - 1) / DEV_BSIZE);
	}
	if (lp && (blkdone >= 0 || bp->b_bcount <= lp->d_secsize)) {
#ifdef tahoe
		sn *= DEV_BSIZE / lp->d_secsize;		/* XXX */
#endif
		sn += lp->d_partitions[part].p_offset;
		(*pr)(" (%s%d bn %d; cn %d", dname, unit, sn,
		    sn / lp->d_secpercyl);
		sn %= lp->d_secpercyl;
		(*pr)(" tn %d sn %d)", sn / lp->d_nsectors, sn % lp->d_nsectors);
	}
}