Ack!

sometime around 1.51, the check for minphys dissappeared out of
transfers for disks..
we weren't hecking that the adapter could handle a transfer of
the size we were requesting..
Peter!?
 :)
this explains the rash of failures I've seen reported recently
with "too many DMA segments" on raw devices

(added one for st as well)

2 files changed, 34 insertions, 15 deletions

diff --git a/sys/scsi/sd.c b/sys/scsi/sd.c
index 71333cc..14438c9 100644
--- a/sys/scsi/sd.c
+++ b/sys/scsi/sd.c
@@ -14,7 +14,7 @@
  *
  * Ported to run under 386BSD by Julian Elischer (julian@dialix.oz.au) Sept 1992
  *
- *      $Id: sd.c,v 1.65 1995/05/30 08:13:51 rgrimes Exp $
+ *      $Id: sd.c,v 1.66 1995/08/07 11:56:31 davidg Exp $
  */
 
 #define SPLSD splbio
@@ -93,18 +93,18 @@ SCSI_DEVICE_ENTRIES(sd)
 
 struct scsi_device sd_switch =
 {
-    sd_sense_handler,
-    sdstart,			/* have a queue, served by this */
-    NULL,			/* have no async handler */
-    NULL,			/* Use default 'done' routine */
-    "sd",
-    0,
+	sd_sense_handler,
+	sdstart,			/* have a queue, served by this */
+	NULL,			/* have no async handler */
+	NULL,			/* Use default 'done' routine */
+	"sd",
+	0,
 	{0, 0},
 	0,				/* Link flags */
 	sdattach,
 	"Direct-Access",
 	sdopen,
-    sizeof(struct scsi_data),
+	sizeof(struct scsi_data),
 	T_DIRECT,
 	sdunit,
 	sdsetunit,
@@ -374,6 +374,11 @@ sd_strategy(struct buf *bp, struct scsi_link *sc_link)
 	}
 
 	/*
+	 * check it's not too big a transfer for our adapter
+	 */
+        scsi_minphys(bp,&sd_switch);
+
+	/*
 	 * Odd number of bytes
 	 */
 	if (bp->b_bcount % DEV_BSIZE != 0) {
diff --git a/sys/scsi/st.c b/sys/scsi/st.c
index 7f56769..b59c9e2 100644
--- a/sys/scsi/st.c
+++ b/sys/scsi/st.c
@@ -12,7 +12,7 @@
  * on the understanding that TFS is not responsible for the correct
  * functioning of this software in any circumstances.
  *
- * $Id: st.c,v 1.37 1995/07/09 08:14:24 joerg Exp $
+ * $Id: st.c,v 1.38 1995/07/16 09:13:14 gibbs Exp $
  */
 
 /*
@@ -904,6 +904,7 @@ st_strategy(struct buf *bp, struct scsi_link *sc_link)
 	unsigned char unit;	/* XXX Everywhere else unit is "u_int32". Please int? */
 	u_int32 opri;
 	struct scsi_data *st;
+	int	len;
 
 	ststrats++;
 	unit = STUNIT((bp->b_dev));
@@ -911,10 +912,14 @@ st_strategy(struct buf *bp, struct scsi_link *sc_link)
 	/*
 	 * If it's a null transfer, return immediatly
 	 */
-	if (bp->b_bcount == 0) {
+	if ((len = bp->b_bcount) == 0) {
 		goto done;
 	}
 	/*
+	 * Check the adapter can do it
+	 */
+	scsi_minphys(bp,&st_switch);
+	/*
 	 * Odd sized request on fixed drives are verboten
 	 */
 	if (st->flags & ST_FIXEDBLOCKS) {
@@ -927,12 +932,21 @@ st_strategy(struct buf *bp, struct scsi_link *sc_link)
 	}
 	/*
 	 * as are out-of-range requests on variable drives.
+	 * (or if we got chopped by minphys)
 	 */
-	else if (bp->b_bcount < st->blkmin || bp->b_bcount > st->blkmax) {
-		printf("st%d: bad request, must be between %ld and %ld\n",
-		    unit, st->blkmin, st->blkmax);
-		bp->b_error = EIO;
-		goto bad;
+	else {
+		if ((bp->b_bcount < st->blkmin || bp->b_bcount > st->blkmax)) {
+			printf("st%d: bad request, must be between %ld and %ld\n",
+		    		unit, st->blkmin, st->blkmax);
+			bp->b_error = EIO;
+			goto bad;
+		}
+		if (len != bp->b_bcount) {
+			printf("st%d: bad request, must be less than %ld bytes\n",
+				unit, bp->b_bcount + 1
+			bp->b_error = EIO;
+			goto bad;
+		}
 	}
 	opri = splbio();