[PATCH 100/117] Staging: hv: storvsc: Optimize the bounce buffer handling in the "read" case

K. Y. Srinivasan
Fri, 15 Jul 2011 17:47:28 -0000

Optimize the bounce buffer handling in the "read" case.

Signed-off-by: K. Y. Srinivasan <kys at microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz at microsoft.com>
---
 drivers/staging/hv/storvsc_drv.c |   10 ++++------
 1 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/staging/hv/storvsc_drv.c b/drivers/staging/hv/storvsc_drv.c
index e2294d5..6e4725f 100644
--- a/drivers/staging/hv/storvsc_drv.c
+++ b/drivers/staging/hv/storvsc_drv.c
@@ -563,12 +563,10 @@ static int storvsc_queuecommand_lck(struct scsi_cmnd
*scmnd,
 				ALIGN(scsi_bufflen(scmnd), PAGE_SIZE) >>
 					PAGE_SHIFT;

-			/*
-			 * FIXME: We can optimize on reads by just skipping
-			 * this
-			 */
-			copy_to_bounce_buffer(sgl, cmd_request->bounce_sgl,
-					      scsi_sg_count(scmnd));
+			if (vm_srb->data_in == WRITE_TYPE)
+				copy_to_bounce_buffer(sgl,
+					cmd_request->bounce_sgl,
+					scsi_sg_count(scmnd));

 			sgl = cmd_request->bounce_sgl;
 			sg_count = cmd_request->bounce_sgl_count;
--
1.7.4.1