[PATCH 4/4] target/rd: T10-Dif: RAM disk is allocating more space than required.

[Quinn Tran <quinn.tran@qlogic.com>]

Ram disk is allocating 8x more space than required for diff data.
For large RAM disk test, there is small potential for memory
starvation.

Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Giridhar Malavali <giridhar.malavali@qlogic.com>
---
 drivers/target/target_core_rd.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/target/target_core_rd.c b/drivers/target/target_core_rd.c
index 01dda0b..6df177a 100644
--- a/drivers/target/target_core_rd.c
+++ b/drivers/target/target_core_rd.c
@@ -253,7 +253,11 @@ static int rd_build_prot_space(struct rd_dev *rd_dev, int prot_length)
 	if (rd_dev->rd_flags & RDF_NULLIO)
 		return 0;
 
-	total_sg_needed = rd_dev->rd_page_count / prot_length;
+	/* prot_length=8byte dif data
+	 * tot sg needed = rd_page_count * (PGSZ/512) * (prot_length/PGSZ) + pad
+	 * PGSZ canceled each other.
+	 */
+	total_sg_needed = (rd_dev->rd_page_count * prot_length / 512) +1;
 
 	sg_tables = (total_sg_needed / max_sg_per_table) + 1;
 
-- 
1.8.4.GIT