[PATCH 3.16 077/328] scsi: virtio_scsi: fix pi_bytes{out,in} on 4 KiB block size devices

[Ben Hutchings]

3.16.62-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Greg Edwards <gedwards@xxxxxxx>

commit cdcdcaae8450a975e7d07e1bfec21f9b8c016d0c upstream.

When the underlying device is a 4 KiB logical block size device with a
protection interval exponent of 0, i.e. 4096 bytes data + 8 bytes PI, the
driver miscalculates the pi_bytes{out,in} by a factor of 8x (64 bytes).

This leads to errors on all reads and writes on 4 KiB logical block size
devices when CONFIG_BLK_DEV_INTEGRITY is enabled and the
VIRTIO_SCSI_F_T10_PI feature bit has been negotiated.

Fixes: e6dc783a38ec0 ("virtio-scsi: Enable DIF/DIX modes in SCSI host LLD")
Acked-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Signed-off-by: Greg Edwards <gedwards@xxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
--- a/drivers/scsi/virtio_scsi.c
+++ b/drivers/scsi/virtio_scsi.c
@@ -500,9 +500,11 @@ static void virtio_scsi_init_hdr_pi(stru
 	bi = blk_get_integrity(rq->rq_disk);
 
 	if (sc->sc_data_direction == DMA_TO_DEVICE)
-		cmd_pi->pi_bytesout = blk_rq_sectors(rq) * bi->tuple_size;
+		cmd_pi->pi_bytesout = bio_integrity_bytes(bi,
+							blk_rq_sectors(rq));
 	else if (sc->sc_data_direction == DMA_FROM_DEVICE)
-		cmd_pi->pi_bytesin = blk_rq_sectors(rq) * bi->tuple_size;
+		cmd_pi->pi_bytesin = bio_integrity_bytes(bi,
+							blk_rq_sectors(rq));
 }
 
 static int virtscsi_queuecommand(struct virtio_scsi *vscsi,