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>
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@ -136,6 +136,8 @@ struct hv_fc_wwn_packet {
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#define SRB_FLAGS_PORT_DRIVER_RESERVED 0x0F000000
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#define SRB_FLAGS_CLASS_DRIVER_RESERVED 0xF0000000
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#define SP_UNTAGGED ((unsigned char) ~0)
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#define SRB_SIMPLE_TAG_REQUEST 0x20
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/*
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* Platform neutral description of a scsi request -
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@ -1549,6 +1551,13 @@ static int storvsc_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scmnd)
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vm_srb->win8_extension.srb_flags |=
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SRB_FLAGS_DISABLE_SYNCH_TRANSFER;
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if (scmnd->device->tagged_supported) {
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vm_srb->win8_extension.srb_flags |=
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(SRB_FLAGS_QUEUE_ACTION_ENABLE | SRB_FLAGS_NO_QUEUE_FREEZE);
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vm_srb->win8_extension.queue_tag = SP_UNTAGGED;
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vm_srb->win8_extension.queue_action = SRB_SIMPLE_TAG_REQUEST;
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}
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/* Build the SRB */
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switch (scmnd->sc_data_direction) {
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case DMA_TO_DEVICE:
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