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Subject[PATCH 29/40] Staging: hv: storvsc: Optimize bounce buffer handling for the "write" case
Date
Optimize bounce buffer handling for the "write" case; we need to copy
from bounce buffer only when we are performing a "read" operation.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Abhishek Kane <v-abkane@microsoft.com>
Signed-off-by: Hank Janssen <hjanssen@microsoft.com>
---
drivers/staging/hv/storvsc_drv.c | 11 ++++++-----
1 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/staging/hv/storvsc_drv.c b/drivers/staging/hv/storvsc_drv.c
index fc53bf6..c6838fd 100644
--- a/drivers/staging/hv/storvsc_drv.c
+++ b/drivers/staging/hv/storvsc_drv.c
@@ -478,17 +478,18 @@ static void storvsc_commmand_completion(struct hv_storvsc_request *request)
struct scsi_sense_hdr sense_hdr;
struct vmscsi_request *vm_srb;

+ vm_srb = &request->vstor_packet.vm_srb;
if (cmd_request->bounce_sgl_count) {

- /* FIXME: We can optimize on writes by just skipping this */
- copy_from_bounce_buffer(scsi_sglist(scmnd),
+ if (vm_srb->data_in == READ_TYPE) {
+ copy_from_bounce_buffer(scsi_sglist(scmnd),
cmd_request->bounce_sgl,
scsi_sg_count(scmnd));
- destroy_bounce_buffer(cmd_request->bounce_sgl,
- cmd_request->bounce_sgl_count);
+ destroy_bounce_buffer(cmd_request->bounce_sgl,
+ cmd_request->bounce_sgl_count);
+ }
}

- vm_srb = &request->vstor_packet.vm_srb;
scmnd->result = vm_srb->scsi_status;

if (scmnd->result) {
--
1.7.4.1


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