ci: fix warnings, enable gosimple linter

Signed-off-by: Kir Kolyshkin <[email protected]>

.golangci.yml

@@ -6,5 +6,4 @@ run:
 linters:
   disable:
     - errcheck
-    - gosimple
     - staticcheck

drivers/overlay/overlay.go

@@ -181,7 +181,7 @@ func getMountProgramFlagFile(path string) string {
 }
 
 func checkSupportVolatile(home, runhome string) (bool, error) {
-	feature := fmt.Sprintf("volatile")
+	const feature = "volatile"
 	volatileCacheResult, _, err := cachedFeatureCheck(runhome, feature)
 	var usingVolatile bool
 	if err == nil {

pkg/devicemapper/devmapper.go

@@ -345,8 +345,7 @@ func RemoveDeviceDeferred(name string) error {
 	// disable udev dm rules and delete the symlink under /dev/mapper by itself,
 	// even if the removal is deferred by the kernel.
 	cookie := new(uint)
-	var flags uint16
-	flags = DmUdevDisableLibraryFallback
+	flags := uint16(DmUdevDisableLibraryFallback)
 	if err := task.setCookie(cookie, flags); err != nil {
 		return fmt.Errorf("devicemapper: Can not set cookie: %s", err)
 	}
@@ -384,7 +383,7 @@ func CancelDeferredRemove(deviceName string) error {
 		return fmt.Errorf("devicemapper: Can't set sector %s", err)
 	}
 
-	if err := task.setMessage(fmt.Sprintf("@cancel_deferred_remove")); err != nil {
+	if err := task.setMessage("@cancel_deferred_remove"); err != nil {
 		return fmt.Errorf("devicemapper: Can't set message %s", err)
 	}
 
@@ -459,8 +458,7 @@ func CreatePool(poolName string, dataFile, metadataFile *os.File, poolBlockSize
 	}
 
 	cookie := new(uint)
-	var flags uint16
-	flags = DmUdevDisableSubsystemRulesFlag | DmUdevDisableDiskRulesFlag | DmUdevDisableOtherRulesFlag
+	flags := uint16(DmUdevDisableSubsystemRulesFlag | DmUdevDisableDiskRulesFlag | DmUdevDisableOtherRulesFlag)
 	if err := task.setCookie(cookie, flags); err != nil {
 		return fmt.Errorf("devicemapper: Can't set cookie %s", err)
 	}