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Subject[PATCH 3.14 092/158] target/rd: T10-Dif: RAM disk is allocating more space than required.
Date
3.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Quinn Tran <quinn.tran@qlogic.com>

commit 9d2e59f2a778328a41771fe9a0098dadbc4314ba upstream.

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

(Use block_size when calculating total_sg_needed - sagi + nab)

Signed-off-by: Giridhar Malavali <giridhar.malavali@qlogic.com>
Signed-off-by: Quinn Tran <quinn.tran@qlogic.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/target/target_core_rd.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)

--- a/drivers/target/target_core_rd.c
+++ b/drivers/target/target_core_rd.c
@@ -242,7 +242,7 @@ static void rd_release_prot_space(struct
rd_dev->sg_prot_count = 0;
}

-static int rd_build_prot_space(struct rd_dev *rd_dev, int prot_length)
+static int rd_build_prot_space(struct rd_dev *rd_dev, int prot_length, int block_size)
{
struct rd_dev_sg_table *sg_table;
u32 total_sg_needed, sg_tables;
@@ -252,8 +252,13 @@ static int rd_build_prot_space(struct rd

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/block_size) *
+ * (prot_length/block_size) + pad
+ * PGSZ canceled each other.
+ */
+ total_sg_needed = (rd_dev->rd_page_count * prot_length / block_size) + 1;

sg_tables = (total_sg_needed / max_sg_per_table) + 1;

@@ -606,7 +611,8 @@ static int rd_init_prot(struct se_device
if (!dev->dev_attrib.pi_prot_type)
return 0;

- return rd_build_prot_space(rd_dev, dev->prot_length);
+ return rd_build_prot_space(rd_dev, dev->prot_length,
+ dev->dev_attrib.block_size);
}

static void rd_free_prot(struct se_device *dev)



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