Avoid hiding disk errors in some cases in FS Shutdown (#2668)

cmd/fs-v1.go

@@ -117,14 +117,16 @@ func (fs fsObjects) Shutdown() error {
 	// List if there are any multipart entries.
 	_, err := fs.storage.ListDir(minioMetaBucket, mpartMetaPrefix)
 	if err != errFileNotFound {
-		// Multipart directory is not empty hence do not remove '.minio.sys' volume.
+		// A nil err means that multipart directory is not empty hence do not remove '.minio.sys' volume.
-		return nil
+		// A non nil err means that an unexpected error occured
+		return err
 	}
 	// List if there are any bucket configuration entries.
 	_, err = fs.storage.ListDir(minioMetaBucket, bucketConfigPrefix)
 	if err != errFileNotFound {
-		// Bucket config directory is not empty hence do not remove '.minio.sys' volume.
+		// A nil err means that bucket config directory is not empty hence do not remove '.minio.sys' volume.
-		return nil
+		// A non nil err means that an unexpected error occured
+		return err
 	}
 	// Cleanup everything else.
 	prefix := ""

cmd/fs-v1_test.go

@@ -17,6 +17,7 @@
 package cmd
 
 import (
+	"bytes"
 	"os"
 	"path/filepath"
 	"testing"
@@ -59,3 +60,39 @@ func TestNewFS(t *testing.T) {
 		}
 	}
 }
+
+// TestFSShutdown - initialize a new FS object layer then calls Shutdown
+// to check returned results
+func TestFSShutdown(t *testing.T) {
+	// Create an FS object and shutdown it. No errors expected
+	disk := filepath.Join(os.TempDir(), "minio-"+nextSuffix())
+	obj, err := newFSObjects(disk)
+	if err != nil {
+		t.Fatal("Cannot create a new FS object: ", err)
+	}
+
+	fs := obj.(fsObjects)
+	fsStorage := fs.storage.(*posix)
+
+	bucketName := "testbucket"
+	objectName := "object"
+	objectContent := "12345"
+
+	obj.MakeBucket(bucketName)
+	obj.PutObject(bucketName, objectName, int64(len(objectContent)), bytes.NewReader([]byte(objectContent)), nil)
+
+	if err := fs.Shutdown(); err != nil {
+		t.Fatal("Cannot shutdown the FS object: ", err)
+	}
+
+	// Create an FS and program errors with disks when shutdown is called
+	for i := 1; i <= 5; i++ {
+		naughty := newNaughtyDisk(fsStorage, map[int]error{i: errFaultyDisk}, nil)
+		fs.storage = naughty
+		if err := fs.Shutdown(); err != errFaultyDisk {
+			t.Fatal(i, ", Got unexpected fs shutdown error: ", err)
+		}
+	}
+
+	removeAll(disk)
+}