libata: convert to chained sg
libata used private sg iterator to handle padding sg. Now that sg can
be chained, padding can be handled using standard sg ops. Convert to
chained sg.
* s/qc->__sg/qc->sg/
* s/qc->pad_sgent/qc->extra_sg[]/. Because chaining consumes one sg
entry. There need to be two extra sg entries. The renaming is also
for future addition of other extra sg entries.
* Padding setup is moved into ata_sg_setup_extra() which is organized
in a way that future addition of other extra sg entries is easy.
* qc->orig_n_elem is unused and removed.
* qc->n_elem now contains the number of sg entries that LLDs should
map. qc->mapped_n_elem is added to carry the original number of
mapped sgs for unmapping.
* The last sg of the original sg list is used to chain to extra sg
list. The original last sg is pointed to by qc->last_sg and the
content is stored in qc->saved_last_sg. It's restored during
ata_sg_clean().
* All sg walking code has been updated. Unnecessary assertions and
checks for conditions the core layer already guarantees are removed.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/ata/sata_qstor.c b/drivers/ata/sata_qstor.c
index 4e5f07b..91cc12c 100644
--- a/drivers/ata/sata_qstor.c
+++ b/drivers/ata/sata_qstor.c
@@ -287,14 +287,10 @@
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;
+ unsigned int si;
- WARN_ON(qc->__sg == NULL);
- WARN_ON(qc->n_elem == 0 && qc->pad_len == 0);
-
- nelem = 0;
- ata_for_each_sg(sg, qc) {
+ for_each_sg(qc->sg, sg, qc->n_elem, si) {
u64 addr;
u32 len;
@@ -306,12 +302,11 @@
*(__le32 *)prd = cpu_to_le32(len);
prd += sizeof(u64);
- VPRINTK("PRD[%u] = (0x%llX, 0x%X)\n", nelem,
+ VPRINTK("PRD[%u] = (0x%llX, 0x%X)\n", si,
(unsigned long long)addr, len);
- nelem++;
}
- return nelem;
+ return si;
}
static void qs_qc_prep(struct ata_queued_cmd *qc)