libata: fix ATAPI DMA alignment issues

ATAPI needs to be padded to next 4 byte boundary, if misaligned.

Original work by me, many fixes from Tejun Heo.

1 files changed, 5 insertions, 3 deletions

diff --git a/drivers/scsi/sata_qstor.c b/drivers/scsi/sata_qstor.c
index ffcdeb68641c..69a9b1cf6f9c 100644
--- a/drivers/scsi/sata_qstor.c
+++ b/drivers/scsi/sata_qstor.c
@@ -268,16 +268,17 @@ static void qs_scr_write (struct ata_port *ap, unsigned int sc_reg, u32 val)
 
 static void qs_fill_sg(struct ata_queued_cmd *qc)
 {
-        struct scatterlist *sg = qc->sg;
+        struct scatterlist *sg;
         struct ata_port *ap = qc->ap;
         struct qs_port_priv *pp = ap->private_data;
         unsigned int nelem;
         u8 *prd = pp->pkt + QS_CPB_BYTES;
 
-        assert(sg != NULL);
+        assert(qc->__sg != NULL);
         assert(qc->n_elem > 0);
 
-        for (nelem = 0; nelem < qc->n_elem; nelem++,sg++) {
+        nelem = 0;
+        ata_for_each_sg(sg, qc) {
                 u64 addr;
                 u32 len;
 
@@ -291,6 +292,7 @@ static void qs_fill_sg(struct ata_queued_cmd *qc)
 
                 VPRINTK("PRD[%u] = (0x%llX, 0x%X)\n", nelem,
                                         (unsigned long long)addr, len);
+                nelem++;
         }
 }