storvsc: force SPC-3 compliance on win8 and win8 r2 hosts

On win8 and win8 r2 hosts force SPC-3 compliance for MSFT virtual disks.
Ubuntu has been carrying a similar patch outside the tree for a while now.
Starting with win10, the host will support SPC-3 compliance. Based on all
the testing that has been done on win8 and win8 r2 hosts, we are comfortable
claiming SPC-3 compliance on these hosts as well. This will enable TRIM
support on these hosts.

Suggested by: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: Long Li <longli@microsoft.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

1 files changed, 13 insertions, 0 deletions

diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index caa9f0ea217c..efc6e446b6c8 100644
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -1394,6 +1394,19 @@ static int storvsc_device_configure(struct scsi_device *sdevice)
          */
         sdevice->sdev_bflags |= msft_blist_flags;
 
+        /*
+         * If the host is WIN8 or WIN8 R2, claim conformance to SPC-3
+         * if the device is a MSFT virtual device.
+         */
+        if (!strncmp(sdevice->vendor, "Msft", 4)) {
+                switch (vmbus_proto_version) {
+                case VERSION_WIN8:
+                case VERSION_WIN8_1:
+                        sdevice->scsi_level = SCSI_SPC_3;
+                        break;
+                }
+        }
+
         return 0;
 }