[libata] kill ata_sg_is_last()

Short term, this works around a bug introduced by early sg-chaining
work.

Long term, removing this function eliminates a branch from a hot
path loop in each scatter/gather table build.  Also, as this code
demonstrates, we don't need to _track_ the end of the s/g list, as
long as we mark it in some way.  And doing so programatically is nice.
So its a useful cleanup, regardless of its short term effects.

Based conceptually on a quick patch by Jens Axboe.

Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 0 insertions, 12 deletions

diff --git a/include/linux/libata.h b/include/linux/libata.h
index 377e6d4d9be3..bc3b6fc7b98d 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -1037,18 +1037,6 @@ extern void ata_port_pbar_desc(struct ata_port *ap, int bar, ssize_t offset,
 /*
  * qc helpers
  */
-static inline int
-ata_sg_is_last(struct scatterlist *sg, struct ata_queued_cmd *qc)
-{
-        if (sg == &qc->pad_sgent)
-                return 1;
-        if (qc->pad_len)
-                return 0;
-        if (qc->n_iter == qc->n_elem)
-                return 1;
-        return 0;
-}
-
 static inline struct scatterlist *
 ata_qc_first_sg(struct ata_queued_cmd *qc)
 {