[PATCH V2 3/8] Drivers: scsi: storvsc: Filter commands based on the storage protocol version

["K. Y. Srinivasan" <kys@microsoft.com>]

Going forward it is possible that some of the commands that are not currently
implemented will be implemented on future Windows hosts. Even if they are not
implemented, we are told the host will corrrectly handle unsupported
commands (by returning appropriate return code and sense information).
Make command filtering depend on the host version.

In this version of the patch I have addressed comments from
Christoph Hellwig <hch@infradead.org>

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Cc: <stable@vger.kernel.org>
---
 drivers/scsi/storvsc_drv.c |   16 +++++++++++++---
 1 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index cebcef7..8f8847e 100644
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -1553,9 +1553,19 @@ static int storvsc_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scmnd)
 	struct vmscsi_request *vm_srb;
 	struct stor_mem_pools *memp = scmnd->device->hostdata;
 
-	if (!storvsc_scsi_cmd_ok(scmnd)) {
-		scmnd->scsi_done(scmnd);
-		return 0;
+	if (vmstor_current_major <= VMSTOR_WIN8_MAJOR) {
+		/*
+		 * On legacy hosts filter unimplemented commands.
+		 * Future hosts are expected to correctly handle
+		 * unsupported commands. Furthermore, it is
+		 * possible that some of the currently
+		 * unsupported commands maybe supported in
+		 * future versions of the host.
+		 */
+		if (!storvsc_scsi_cmd_ok(scmnd)) {
+			scmnd->scsi_done(scmnd);
+			return 0;
+		}
 	}
 
 	request_size = sizeof(struct storvsc_cmd_request);
-- 
1.7.4.1