[PATCH V4 05/31] smartpqi: refactor build sg list code

[Don Brace <don.brace@xxxxxxxxxxxxx>]

* No functional changes.
* Factor out code common to all s/g list building.
* Prepare for new AIO functionality.
  AIO - Accelerated I/O, AIO requests go directly to disk

Reviewed-by: Scott Benesh <scott.benesh@xxxxxxxxxxxxx>
Reviewed-by: Mike McGowen <mike.mcgowen@xxxxxxxxxxxxx>
Reviewed-by: Scott Teel <scott.teel@xxxxxxxxxxxxx>
Reviewed-by: Kevin Barnett <kevin.barnett@xxxxxxxxxxxxx>
Reviewed-by: Martin Wilck <mwilck@xxxxxxxx>
Signed-off-by: Don Brace <don.brace@xxxxxxxxxxxxx>
---
 drivers/scsi/smartpqi/smartpqi_init.c |  101 ++++++++++++++-------------------
 1 file changed, 42 insertions(+), 59 deletions(-)

diff --git a/drivers/scsi/smartpqi/smartpqi_init.c b/drivers/scsi/smartpqi/smartpqi_init.c
index 0d615b20b23a..5d65464040df 100644
--- a/drivers/scsi/smartpqi/smartpqi_init.c
+++ b/drivers/scsi/smartpqi/smartpqi_init.c
@@ -4857,16 +4857,52 @@ static inline void pqi_set_sg_descriptor(
 	put_unaligned_le32(0, &sg_descriptor->flags);
 }
 
+static unsigned int pqi_build_sg_list(struct pqi_sg_descriptor *sg_descriptor,
+	struct scatterlist *sg, int sg_count, struct pqi_io_request *io_request,
+	int max_sg_per_iu, bool *chained)
+{
+	int i;
+	unsigned int num_sg_in_iu;
+
+	*chained = false;
+	i = 0;
+	num_sg_in_iu = 0;
+	max_sg_per_iu--;	/* Subtract 1 to leave room for chain marker. */
+
+	while (1) {
+		pqi_set_sg_descriptor(sg_descriptor, sg);
+		if (!*chained)
+			num_sg_in_iu++;
+		i++;
+		if (i == sg_count)
+			break;
+		sg_descriptor++;
+		if (i == max_sg_per_iu) {
+			put_unaligned_le64((u64)io_request->sg_chain_buffer_dma_handle,
+				&sg_descriptor->address);
+			put_unaligned_le32((sg_count - num_sg_in_iu) * sizeof(*sg_descriptor),
+				&sg_descriptor->length);
+			put_unaligned_le32(CISS_SG_CHAIN, &sg_descriptor->flags);
+			*chained = true;
+			num_sg_in_iu++;
+			sg_descriptor = io_request->sg_chain_buffer;
+		}
+		sg = sg_next(sg);
+	}
+
+	put_unaligned_le32(CISS_SG_LAST, &sg_descriptor->flags);
+
+	return num_sg_in_iu;
+}
+
 static int pqi_build_raid_sg_list(struct pqi_ctrl_info *ctrl_info,
 	struct pqi_raid_path_request *request, struct scsi_cmnd *scmd,
 	struct pqi_io_request *io_request)
 {
-	int i;
 	u16 iu_length;
 	int sg_count;
 	bool chained;
 	unsigned int num_sg_in_iu;
-	unsigned int max_sg_per_iu;
 	struct scatterlist *sg;
 	struct pqi_sg_descriptor *sg_descriptor;
 
@@ -4882,36 +4918,10 @@ static int pqi_build_raid_sg_list(struct pqi_ctrl_info *ctrl_info,
 
 	sg = scsi_sglist(scmd);
 	sg_descriptor = request->sg_descriptors;
-	max_sg_per_iu = ctrl_info->max_sg_per_iu - 1;
-	chained = false;
-	num_sg_in_iu = 0;
-	i = 0;
 
-	while (1) {
-		pqi_set_sg_descriptor(sg_descriptor, sg);
-		if (!chained)
-			num_sg_in_iu++;
-		i++;
-		if (i == sg_count)
-			break;
-		sg_descriptor++;
-		if (i == max_sg_per_iu) {
-			put_unaligned_le64(
-				(u64)io_request->sg_chain_buffer_dma_handle,
-				&sg_descriptor->address);
-			put_unaligned_le32((sg_count - num_sg_in_iu)
-				* sizeof(*sg_descriptor),
-				&sg_descriptor->length);
-			put_unaligned_le32(CISS_SG_CHAIN,
-				&sg_descriptor->flags);
-			chained = true;
-			num_sg_in_iu++;
-			sg_descriptor = io_request->sg_chain_buffer;
-		}
-		sg = sg_next(sg);
-	}
+	num_sg_in_iu = pqi_build_sg_list(sg_descriptor, sg, sg_count, io_request,
+		ctrl_info->max_sg_per_iu, &chained);
 
-	put_unaligned_le32(CISS_SG_LAST, &sg_descriptor->flags);
 	request->partial = chained;
 	iu_length += num_sg_in_iu * sizeof(*sg_descriptor);
 
@@ -4925,12 +4935,10 @@ static int pqi_build_aio_sg_list(struct pqi_ctrl_info *ctrl_info,
 	struct pqi_aio_path_request *request, struct scsi_cmnd *scmd,
 	struct pqi_io_request *io_request)
 {
-	int i;
 	u16 iu_length;
 	int sg_count;
 	bool chained;
 	unsigned int num_sg_in_iu;
-	unsigned int max_sg_per_iu;
 	struct scatterlist *sg;
 	struct pqi_sg_descriptor *sg_descriptor;
 
@@ -4947,35 +4955,10 @@ static int pqi_build_aio_sg_list(struct pqi_ctrl_info *ctrl_info,
 
 	sg = scsi_sglist(scmd);
 	sg_descriptor = request->sg_descriptors;
-	max_sg_per_iu = ctrl_info->max_sg_per_iu - 1;
-	chained = false;
-	i = 0;
 
-	while (1) {
-		pqi_set_sg_descriptor(sg_descriptor, sg);
-		if (!chained)
-			num_sg_in_iu++;
-		i++;
-		if (i == sg_count)
-			break;
-		sg_descriptor++;
-		if (i == max_sg_per_iu) {
-			put_unaligned_le64(
-				(u64)io_request->sg_chain_buffer_dma_handle,
-				&sg_descriptor->address);
-			put_unaligned_le32((sg_count - num_sg_in_iu)
-				* sizeof(*sg_descriptor),
-				&sg_descriptor->length);
-			put_unaligned_le32(CISS_SG_CHAIN,
-				&sg_descriptor->flags);
-			chained = true;
-			num_sg_in_iu++;
-			sg_descriptor = io_request->sg_chain_buffer;
-		}
-		sg = sg_next(sg);
-	}
+	num_sg_in_iu = pqi_build_sg_list(sg_descriptor, sg, sg_count, io_request,
+		ctrl_info->max_sg_per_iu, &chained);
 
-	put_unaligned_le32(CISS_SG_LAST, &sg_descriptor->flags);
 	request->partial = chained;
 	iu_length += num_sg_in_iu * sizeof(*sg_descriptor);