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

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>
Cc: <stable@vger.kernel.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
hifive-unleashed-5.1
Long Li 2016-12-14 18:46:01 -08:00 committed by Martin K. Petersen
parent d86adf482b
commit 3cd6d3d9b1
1 changed files with 9 additions and 0 deletions
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9
drivers/scsi/storvsc_drv.c
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@ -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 -
@ -1549,6 +1551,13 @@ static int storvsc_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scmnd)
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: