i think i got this right....

1 files changed, 14 insertions, 12 deletions

diff --git a/sys/arch/pmax/pmax/disksubr.c b/sys/arch/pmax/pmax/disksubr.c
index cf3836bfaa2..1c4dbf6a243 100644
--- a/sys/arch/pmax/pmax/disksubr.c
+++ b/sys/arch/pmax/pmax/disksubr.c
@@ -311,38 +311,40 @@ bounds_check_with_label(bp, lp, wlabel)
 	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;
-	int sz = (bp->b_bcount + DEV_BSIZE - 1) >> DEV_BSHIFT;
+#define blockpersec(count, lp) ((count) * (((lp)->d_secsize) / DEV_BSIZE))
+	struct partition *p = lp->d_partitions + DISKPART(bp->b_dev);
+	int labelsect = blockpersec(lp->d_partitions[0].p_offset, lp) +
+	    LABELSECTOR;
+	int sz = howmany(bp->b_bcount, DEV_BSIZE);
 
 	/* overwriting disk label ? */
 	/* XXX should also protect bootstrap in first 8K */ 
-	if (bp->b_blkno + p->p_offset <= LABELSECTOR + labelsect &&
+	if (bp->b_blkno + blockpersec(p->p_offset, lp) <= labelsect &&
 	    (bp->b_flags & B_READ) == 0 && wlabel == 0) {
 		bp->b_error = EROFS;
 		goto bad;
 	}
 
 	/* 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) {
+	if (bp->b_blkno + sz > blockpersec(p->p_size, lp)) {
+		sz = blockpersec(p->p_size, lp) - bp->b_blkno;
+		if (sz == 0) {
+			/* if exactly at end of disk, return an EOF */
 			bp->b_resid = bp->b_bcount;
 			return(0);
 		}
-		/* or truncate if part of it fits */
 		sz = maxsz - bp->b_blkno;
-		if (sz <= 0) {
+		if (sz < 0) {
 			bp->b_error = EINVAL;
 			goto bad;
 		}
+		/* or truncate if part of it fits */
 		bp->b_bcount = sz << DEV_BSHIFT;
 	}               
 
 	/* calculate cylinder for disksort to order transfers with */
-	bp->b_resid = (bp->b_blkno + p->p_offset) / lp->d_secpercyl;
+	bp->b_resid = (bp->b_blkno + blockpersec(p->p_offset, lp)) /
+	    lp->d_secpercyl;
 	return(1);
 bad:
 	bp->b_flags |= B_ERROR;