[PATCH 4.9 058/153] scsi: storvsc: use tagged SRB requests if supported by the device

Greg Kroah-Hartman
2017-03-10T09:20:03Z

From: Long Li <longli@microsoft.com>

commit 3cd6d3d9b1abab8dcdf0800224ce26daac24eea2 upstream.

Properly set SRB flags when hosting device supports tagged queuing.
This patch improves the performance on Fiber Channel disks.

Signed-off-by: Long Li <longli@microsoft.com>
Reviewed-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/scsi/storvsc_drv.c | 9 +++++++++
1 file changed, 9 insertions(+)

--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -136,6 +136,8 @@ struct hv_fc_wwn_packet {
#define SRB_FLAGS_PORT_DRIVER_RESERVED 0x0F000000
#define SRB_FLAGS_CLASS_DRIVER_RESERVED 0xF0000000

+#define SP_UNTAGGED ((unsigned char) ~0)
+#define SRB_SIMPLE_TAG_REQUEST 0x20

/*
* Platform neutral description of a scsi request -
@@ -1451,6 +1453,13 @@ static int storvsc_queuecommand(struct S
vm_srb->win8_extension.srb_flags |=
SRB_FLAGS_DISABLE_SYNCH_TRANSFER;

+ if (scmnd->device->tagged_supported) {
+ vm_srb->win8_extension.srb_flags |=
+ (SRB_FLAGS_QUEUE_ACTION_ENABLE | SRB_FLAGS_NO_QUEUE_FREEZE);
+ vm_srb->win8_extension.queue_tag = SP_UNTAGGED;
+ vm_srb->win8_extension.queue_action = SRB_SIMPLE_TAG_REQUEST;
+ }
+
/* Build the SRB */
switch (scmnd->sc_data_direction) {