[PATCH 3.4 022/125] megaraid_sas: Do not use PAGE_SIZE for max_sectors

[lizf]

From: "sumit.saxena@xxxxxxxxxxxxx" <sumit.saxena@xxxxxxxxxxxxx>

3.4.113-rc1 review patch.  If anyone has any objections, please let me know.

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


commit 357ae967ad66e357f78b5cfb5ab6ca07fb4a7758 upstream.

Do not use PAGE_SIZE marco to calculate max_sectors per I/O
request. Driver code assumes PAGE_SIZE will be always 4096 which can
lead to wrongly calculated value if PAGE_SIZE is not 4096. This issue
was reported in Ubuntu Bugzilla Bug #1475166.

Signed-off-by: Sumit Saxena <sumit.saxena@xxxxxxxxxxxxx>
Signed-off-by: Kashyap Desai <kashyap.desai@xxxxxxxxxxxxx>
Reviewed-by: Tomas Henzl <thenzl@xxxxxxxxxx>
Reviewed-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Signed-off-by: Zefan Li <lizefan@xxxxxxxxxx>
---
 drivers/scsi/megaraid/megaraid_sas.h      | 2 ++
 drivers/scsi/megaraid/megaraid_sas_base.c | 2 +-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/megaraid/megaraid_sas.h b/drivers/scsi/megaraid/megaraid_sas.h
index 1a7955a..0eaf196 100644
--- a/drivers/scsi/megaraid/megaraid_sas.h
+++ b/drivers/scsi/megaraid/megaraid_sas.h
@@ -300,6 +300,8 @@ enum MR_EVT_ARGS {
 	MR_EVT_ARGS_GENERIC,
 };
 
+
+#define SGE_BUFFER_SIZE	4096
 /*
  * define constants for device list query options
  */
diff --git a/drivers/scsi/megaraid/megaraid_sas_base.c b/drivers/scsi/megaraid/megaraid_sas_base.c
index bacd344..a74dc74 100644
--- a/drivers/scsi/megaraid/megaraid_sas_base.c
+++ b/drivers/scsi/megaraid/megaraid_sas_base.c
@@ -3582,7 +3582,7 @@ static int megasas_init_fw(struct megasas_instance *instance)
 	}
 
 	instance->max_sectors_per_req = instance->max_num_sge *
-						PAGE_SIZE / 512;
+						SGE_BUFFER_SIZE / 512;
 	if (tmp_sectors && (instance->max_sectors_per_req > tmp_sectors))
 		instance->max_sectors_per_req = tmp_sectors;
 
-- 
1.9.1