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Message-Id: <1309358377-8537-30-git-send-email-kys@microsoft.com>
Date:	Wed, 29 Jun 2011 07:39:27 -0700
From:	"K. Y. Srinivasan" <kys@...rosoft.com>
To:	gregkh@...e.de, linux-kernel@...r.kernel.org,
	devel@...uxdriverproject.org, virtualization@...ts.osdl.org
Cc:	"K. Y. Srinivasan" <kys@...rosoft.com>,
	Haiyang Zhang <haiyangz@...rosoft.com>,
	Abhishek Kane <v-abkane@...rosoft.com>,
	Hank Janssen <hjanssen@...rosoft.com>
Subject: [PATCH 30/40] Staging: hv: storvsc: Optimize the bounce buffer handling in the "read" case

Optimize the bounce buffer handling in the "read" case. Copy to bounce
buffers (if needed) when we initiate an I/O, only if we are
performing a "write" operation.

Signed-off-by: K. Y. Srinivasan <kys@...rosoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@...rosoft.com>
Signed-off-by: Abhishek Kane <v-abkane@...rosoft.com>
Signed-off-by: Hank Janssen <hjanssen@...rosoft.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 c6838fd..23334ad 100644
--- a/drivers/staging/hv/storvsc_drv.c
+++ b/drivers/staging/hv/storvsc_drv.c
@@ -623,12 +623,10 @@ 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

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