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-rw-r--r--drivers/scsi/libata-core.c15
-rw-r--r--drivers/scsi/sata_qstor.c2
-rw-r--r--include/linux/libata.h16
3 files changed, 24 insertions, 9 deletions
diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 7ddd5a69352a..5f1d7580218d 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -2514,7 +2514,7 @@ static void ata_sg_clean(struct ata_queued_cmd *qc)
assert(sg != NULL);
if (qc->flags & ATA_QCFLAG_SINGLE)
- assert(qc->n_elem == 1);
+ assert(qc->n_elem <= 1);
VPRINTK("unmapping %u sg elements\n", qc->n_elem);
@@ -2537,7 +2537,7 @@ static void ata_sg_clean(struct ata_queued_cmd *qc)
kunmap_atomic(addr, KM_IRQ0);
}
} else {
- if (sg_dma_len(&sg[0]) > 0)
+ if (qc->n_elem)
dma_unmap_single(ap->host_set->dev,
sg_dma_address(&sg[0]), sg_dma_len(&sg[0]),
dir);
@@ -2570,7 +2570,7 @@ static void ata_fill_sg(struct ata_queued_cmd *qc)
unsigned int idx;
assert(qc->__sg != NULL);
- assert(qc->n_elem > 0);
+ assert(qc->n_elem > 0 || qc->pad_len > 0);
idx = 0;
ata_for_each_sg(sg, qc) {
@@ -2715,6 +2715,7 @@ static int ata_sg_setup_one(struct ata_queued_cmd *qc)
int dir = qc->dma_dir;
struct scatterlist *sg = qc->__sg;
dma_addr_t dma_address;
+ int trim_sg = 0;
/* we must lengthen transfers to end on a 32-bit boundary */
qc->pad_len = sg->length & 3;
@@ -2734,13 +2735,15 @@ static int ata_sg_setup_one(struct ata_queued_cmd *qc)
sg_dma_len(psg) = ATA_DMA_PAD_SZ;
/* trim sg */
sg->length -= qc->pad_len;
+ if (sg->length == 0)
+ trim_sg = 1;
DPRINTK("padding done, sg->length=%u pad_len=%u\n",
sg->length, qc->pad_len);
}
- if (!sg->length) {
- sg_dma_address(sg) = 0;
+ if (trim_sg) {
+ qc->n_elem--;
goto skip_map;
}
@@ -2753,9 +2756,9 @@ static int ata_sg_setup_one(struct ata_queued_cmd *qc)
}
sg_dma_address(sg) = dma_address;
-skip_map:
sg_dma_len(sg) = sg->length;
+skip_map:
DPRINTK("mapped buffer of %d bytes for %s\n", sg_dma_len(sg),
qc->tf.flags & ATA_TFLAG_WRITE ? "write" : "read");
diff --git a/drivers/scsi/sata_qstor.c b/drivers/scsi/sata_qstor.c
index de05e2883f9c..80480f0fb2b8 100644
--- a/drivers/scsi/sata_qstor.c
+++ b/drivers/scsi/sata_qstor.c
@@ -277,7 +277,7 @@ static unsigned int qs_fill_sg(struct ata_queued_cmd *qc)
u8 *prd = pp->pkt + QS_CPB_BYTES;
assert(qc->__sg != NULL);
- assert(qc->n_elem > 0);
+ assert(qc->n_elem > 0 || qc->pad_len > 0);
nelem = 0;
ata_for_each_sg(sg, qc) {
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 9e5db2949c58..c91be5e64ede 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -557,17 +557,29 @@ ata_sg_is_last(struct scatterlist *sg, struct ata_queued_cmd *qc)
}
static inline struct scatterlist *
+ata_qc_first_sg(struct ata_queued_cmd *qc)
+{
+ if (qc->n_elem)
+ return qc->__sg;
+ if (qc->pad_len)
+ return &qc->pad_sgent;
+ return NULL;
+}
+
+static inline struct scatterlist *
ata_qc_next_sg(struct scatterlist *sg, struct ata_queued_cmd *qc)
{
if (sg == &qc->pad_sgent)
return NULL;
if (++sg - qc->__sg < qc->n_elem)
return sg;
- return qc->pad_len ? &qc->pad_sgent : NULL;
+ if (qc->pad_len)
+ return &qc->pad_sgent;
+ return NULL;
}
#define ata_for_each_sg(sg, qc) \
- for (sg = qc->__sg; sg; sg = ata_qc_next_sg(sg, qc))
+ for (sg = ata_qc_first_sg(qc); sg; sg = ata_qc_next_sg(sg, qc))
static inline unsigned int ata_tag_valid(unsigned int tag)
{