[PATCH] PATCH: (as70b) Update request_bufflen to match this_count

This patch addresses a problem in both sd.c and sr.c.  When a read/write
command is initialized, the routines may reduce this_count (the number of
sectors to transfer) if it exceeds the maximum allowed value (i.e., 0xffff
for READ(10)).  However, the code does not similarly alter
scmd->request_bufflen and scmd->bufflen to match the change in the CDB
value.

scmd->request_bufflen is important for the usb-storage driver, which
requires that it be exactly equal to the number of bytes transferred.
scmd->bufflen is used in the rw_intr() routines, where it is passed to
scsi_io_completion() as the number of sectors transferred if no errors
occur.

Another small change in the patch concerns the code in sr.c that checks
whether the total of the scatter-gather area lengths matches
scmd->request_bufflen.  If they don't match, the patch bumps the kernel
log message level up to KERN_ERR, and it takes the more conservative
approach of adjusting scmd->request_bufflen only if the s-g length is
smaller than the request length.

drivers/scsi/sd.c

@@ -308,6 +308,8 @@ static int sd_init_command(struct scsi_cmnd * SCpnt)
 		SCpnt->cmnd[4] = (unsigned char) this_count;
 		SCpnt->cmnd[5] = 0;
 	}
+	SCpnt->request_bufflen = SCpnt->bufflen =
+			this_count * sdp->sector_size;
 
 	/*
 	 * We shouldn't disconnect in the middle of a sector, so with a dumb

drivers/scsi/sr.c

@@ -340,6 +340,20 @@ static int sr_init_command(struct scsi_cmnd * SCpnt)
 		return 0;
 	}
 
+	{
+		struct scatterlist *sg = SCpnt->request_buffer;
+		int i, size = 0;
+		for (i = 0; i < SCpnt->use_sg; i++)
+			size += sg[i].length;
+
+		if (size != SCpnt->request_bufflen && SCpnt->use_sg) {
+			printk(KERN_ERR "sr: mismatch count %d, bytes %d\n",
+					size, SCpnt->request_bufflen);
+			if (SCpnt->request_bufflen > size)
+				SCpnt->request_bufflen = SCpnt->bufflen = size;
+		}
+	}
+
 	/*
 	 * request doesn't start on hw block boundary, add scatter pads
 	 */
@@ -361,8 +375,11 @@ static int sr_init_command(struct scsi_cmnd * SCpnt)
 	SCpnt->cmnd[1] = 0;
 	block = (unsigned int)SCpnt->request->sector / (s_size >> 9);
 
-	if (this_count > 0xffff)
+	if (this_count > 0xffff) {
 		this_count = 0xffff;
+		SCpnt->request_bufflen = SCpnt->bufflen =
+				this_count * s_size;
+	}
 
 	SCpnt->cmnd[2] = (unsigned char) (block >> 24) & 0xff;
 	SCpnt->cmnd[3] = (unsigned char) (block >> 16) & 0xff;
@@ -390,18 +407,6 @@ static int sr_init_command(struct scsi_cmnd * SCpnt)
 	 */
 	SCpnt->done = rw_intr;
 
-	{
-		struct scatterlist *sg = SCpnt->request_buffer;
-		int i, size = 0;
-		for (i = 0; i < SCpnt->use_sg; i++)
-			size += sg[i].length;
-
-		if (size != SCpnt->request_bufflen && SCpnt->use_sg) {
-			printk("sr: mismatch count %d, bytes %d\n", size, SCpnt->request_bufflen);
-			SCpnt->request_bufflen = size;
-		}
-	}
-
 	/*
 	 * This indicates that the command is ready from our end to be
 	 * queued.