devmapper: use proper DM_UDEV_DISABLE_*_FLAG when creating the thin-pool

Otherwise udev can unecessarily execute various rules (and issue
scanning IO, etc) against the thin-pool -- which can never be a
top-level device.

Docker-DCO-1.1-Signed-off-by: Mike Snitzer <snitzer@redhat.com> (github: snitm)

pkg/devicemapper/devmapper.go

@@ -361,7 +361,8 @@ func CreatePool(poolName string, dataFile, metadataFile *os.File, poolBlockSize
 	}
 
 	var cookie uint = 0
-	if err := task.SetCookie(&cookie, 0); err != nil {
+	var flags uint16 = DmUdevDisableSubsystemRulesFlag | DmUdevDisableDiskRulesFlag | DmUdevDisableOtherRulesFlag
+	if err := task.SetCookie(&cookie, flags); err != nil {
 		return fmt.Errorf("Can't set cookie %s", err)
 	}
 

pkg/devicemapper/devmapper_wrapper.go

@@ -82,6 +82,12 @@ const (
 	LoNameSize       = C.LO_NAME_SIZE
 )
 
+const (
+	DmUdevDisableSubsystemRulesFlag = C.DM_UDEV_DISABLE_SUBSYSTEM_RULES_FLAG
+	DmUdevDisableDiskRulesFlag      = C.DM_UDEV_DISABLE_DISK_RULES_FLAG
+	DmUdevDisableOtherRulesFlag     = C.DM_UDEV_DISABLE_OTHER_RULES_FLAG
+)
+
 var (
 	DmGetLibraryVersion    = dmGetLibraryVersionFct
 	DmGetNextTarget        = dmGetNextTargetFct