Patch "scsi: storvsc: use tagged SRB requests if supported by the device" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

scsi: storvsc: use tagged SRB requests if supported by the device

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
scsi-storvsc-use-tagged-srb-requests-if-supported-by-the-device.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Long Li <[email protected]>
Date: Wed, 14 Dec 2016 18:46:01 -0800
Subject: scsi: storvsc: use tagged SRB requests if supported by the device

From: Long Li <[email protected]>

commit 3cd6d3d9b1abab8dcdf0800224ce26daac24eea2 upstream.

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

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

@@ -135,6 +135,8 @@ 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 -

@@ -1409,6 +1411,13 @@ 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) {
 	case DMA_TO_DEVICE:

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/scsi-storvsc-use-tagged-srb-requests-if-supported-by-the-device.patch queue-4.4/scsi-storvsc-properly-set-residual-data-length-on-errors.patch queue-4.4/scsi-storvsc-properly-handle-srb_error-when-sense-message-is-present.patch