From: Bart Van Assche <bart.vanassche@sandisk.com>
Date: Fri, 2 Jun 2017 14:21:59 -0700
Subject: [PATCH] scsi: Introduce scsi_mq_sgl_size()
References: bsc#1061782
Git-commit: be4c186c80113f95a5946594687a8e70f876e857
Patch-Mainline: v4.13-rc1

This patch does not change any functionality but makes the next patch
easier to read.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Hannes Reinecke <hare@suse.de>
---
 drivers/scsi/scsi_lib.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index a2a9866..8127785 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1855,6 +1855,13 @@ static inline blk_status_t prep_to_mq(int ret)
 	}
 }
 
+/* Size in bytes of the sg-list stored in the scsi-mq command-private data. */
+static unsigned int scsi_mq_sgl_size(struct Scsi_Host *shost)
+{
+	return min_t(unsigned int, shost->sg_tablesize, SG_CHUNK_SIZE) *
+		sizeof(struct scatterlist);
+}
+
 static int scsi_mq_prep_fn(struct request *req)
 {
 	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
@@ -1889,10 +1896,7 @@ static int scsi_mq_prep_fn(struct request *req)
 	cmd->sdb.table.sgl = sg;
 
 	if (scsi_host_get_prot(shost)) {
-		cmd->prot_sdb = (void *)sg +
-			min_t(unsigned int,
-			      shost->sg_tablesize, SG_CHUNK_SIZE) *
-			sizeof(struct scatterlist);
+		cmd->prot_sdb = (void *)sg + scsi_mq_sgl_size(shost);
 		memset(cmd->prot_sdb, 0, sizeof(struct scsi_data_buffer));
 
 		cmd->prot_sdb->table.sgl =
@@ -2202,12 +2206,9 @@ struct request_queue *scsi_mq_alloc_queue(struct scsi_device *sdev)
 
 int scsi_mq_setup_tags(struct Scsi_Host *shost)
 {
-	unsigned int cmd_size, sgl_size, tbl_size;
+	unsigned int cmd_size, sgl_size;
 
-	tbl_size = shost->sg_tablesize;
-	if (tbl_size > SG_CHUNK_SIZE)
-		tbl_size = SG_CHUNK_SIZE;
-	sgl_size = tbl_size * sizeof(struct scatterlist);
+	sgl_size = scsi_mq_sgl_size(shost);
 	cmd_size = sizeof(struct scsi_cmnd) + shost->hostt->cmd_size + sgl_size;
 	if (scsi_host_get_prot(shost))
 		cmd_size += sizeof(struct scsi_data_buffer) + sgl_size;
-- 
1.8.5.6