diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 1470c93a87e7f4024618fed3a8ee0570ade04485..c2a9601bd3020487bb7e132810fdfaacfc994eb2 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1859,6 +1859,13 @@ static inline int 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);
@@ -1893,10 +1900,7 @@ 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;