1 files changed, 12 insertions, 2 deletions

diff --git a/drivers/scsi/libata-scsi.c b/drivers/scsi/libata-scsi.c
index 104fd9a63e73..ee3f1050fb5f 100644
--- a/drivers/scsi/libata-scsi.c
+++ b/drivers/scsi/libata-scsi.c
@@ -150,10 +150,10 @@ struct ata_queued_cmd *ata_scsi_qc_new(struct ata_port *ap,
                 qc->scsidone = done;
 
                 if (cmd->use_sg) {
-                        qc->sg = (struct scatterlist *) cmd->request_buffer;
+                        qc->__sg = (struct scatterlist *) cmd->request_buffer;
                         qc->n_elem = cmd->use_sg;
                 } else {
-                        qc->sg = &qc->sgent;
+                        qc->__sg = &qc->sgent;
                         qc->n_elem = 1;
                 }
         } else {
@@ -364,6 +364,16 @@ int ata_scsi_slave_config(struct scsi_device *sdev)
                          */
                         blk_queue_max_sectors(sdev->request_queue, 2048);
                 }
+
+                /*
+                 * SATA DMA transfers must be multiples of 4 byte, so
+                 * we need to pad ATAPI transfers using an extra sg.
+                 * Decrement max hw segments accordingly.
+                 */
+                if (dev->class == ATA_DEV_ATAPI) {
+                        request_queue_t *q = sdev->request_queue;
+                        blk_queue_max_hw_segments(q, q->max_hw_segments - 1);
+                }
         }
 
         return 0;       /* scsi layer doesn't check return value, sigh */