Added check for multipath device mapper

Addressed review comments

pkg/volume/fc/fc_util_linux_test.go

@@ -0,0 +1,72 @@
+//go:build linux
+// +build linux
+
+/*
+Copyright 2024 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package fc
+
+import (
+	"testing"
+
+	"k8s.io/kubernetes/pkg/volume/util"
+)
+
+func TestSearchDiskMultipathDevice(t *testing.T) {
+	tests := []struct {
+		name        string
+		wwns        []string
+		lun         string
+		expectError bool
+	}{
+		{
+			name: "Non PCI disk 0",
+			wwns: []string{"500507681021a537"},
+			lun:  "0",
+		},
+		{
+			name: "Non PCI disk 1",
+			wwns: []string{"500507681022a554"},
+			lun:  "2",
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			fakeMounter := fcDiskMounter{
+				fcDisk: &fcDisk{
+					wwns: test.wwns,
+					lun:  test.lun,
+					io:   &fakeIOHandler{},
+				},
+				deviceUtil: util.NewDeviceHandler(&fakeIOHandler{}),
+			}
+			devicePath, err := searchDisk(fakeMounter)
+			if test.expectError && err == nil {
+				t.Errorf("expected error but got none")
+			}
+			if !test.expectError && err != nil {
+				t.Errorf("got unexpected error: %s", err)
+			}
+			// if no disk matches input wwn and lun, exit
+			if devicePath == "" && !test.expectError {
+				t.Errorf("no fc disk found")
+			}
+			if devicePath != "/dev/dm-1" {
+				t.Errorf("multipath device not found dm-1 expected got [%s]", devicePath)
+			}
+		})
+	}
+}