enable UNMAP when LUN is thin provisioned

- support Block Limits VPD page (0xB0)
 - add UNMAP to REPORT SUPPORTED OPERATION CODES
 - READ CAPACITY(16): set LBPME when Thin provisioning is enabled
 - move Thinprovisioning and BlockShift to config
 - add Unmap to BackingStore

pkg/scsi/sbc.go

@@ -295,7 +295,13 @@ sense:
 }
 
 func SBCUnmap(host int, cmd *api.SCSICommand) api.SAMStat {
-	return api.SAMStatGood
+	err, key, asc := bsPerformCommand(cmd.Device.Storage, cmd)
+	if err == nil {
+		return api.SAMStatGood
+	}
+
+	BuildSenseData(cmd, key, asc)
+	return api.SAMStatCheckCondition
 }
 
 /*
@@ -594,7 +600,11 @@ func SBCReadCapacity16(host int, cmd *api.SCSICommand) api.SAMStat {
 	if allocationLength > 12 {
 		copy(cmd.InSDBBuffer.Buffer[8:], util.MarshalUint32(uint32(1<<bshift)))
 		if allocationLength > 16 {
-			val := (cmd.Device.Attrs.Lbppbe << 16) | cmd.Device.Attrs.LowestAlignedLBA
+			var lbpme int
+			if cmd.Device.Attrs.Thinprovisioning {
+				lbpme = 1
+			}
+			val := (cmd.Device.Attrs.Lbppbe << 16) | (lbpme << 15) | cmd.Device.Attrs.LowestAlignedLBA
 			copy(cmd.InSDBBuffer.Buffer[12:], util.MarshalUint32(uint32(val)))
 		}
 	}