i think i got this right....

diff --git a/sys/arch/pmax/pmax/disksubr.c b/sys/arch/pmax/pmax/disksubr.c
index cf3836b..1c4dbf6 100644 (file)
--- 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;