fix(zfspv): rounding off the volume size to Gi and Mi (#191)

ZFS does not create the zvol if volume size is not multiple of
the volblocksize. There are use cases where customer will create
a PVC with size as 5G, which will be 5 * 1000 * 1000 * 1000 bytes
and this is not the multiple of default volblocksize 8k.

In ZFS, volblocksize and recordsize must be power of 2 from 512B to 1M,
so keeping the size in the form of Gi or Mi should be
sufficient to make volsize multiple of volblocksize/recordsize.


Signed-off-by: Pawan <pawan@mayadata.io>

pkg/driver/controller_test.go

@@ -0,0 +1,45 @@
+/*
+Copyright 2020 The OpenEBS 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 driver
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestRoundOff(t *testing.T) {
+
+	tests := map[string]struct {
+		input    int64
+		expected int64
+	}{
+		"Minimum allocatable is 1Mi": {input: 1, expected: Mi},
+		"roundOff to same Mi size":   {input: Mi, expected: Mi},
+		"roundOff to nearest Mi":     {input: Mi + 1, expected: Mi * 2},
+		"roundOff to same Gi size":   {input: Gi, expected: Gi},
+		"roundOff to nearest Gi":     {input: Gi + 1, expected: Gi * 2},
+		"roundOff MB size":           {input: 5 * MB, expected: 5 * Mi},
+		"roundOff GB size":           {input: 5 * GB, expected: 5 * Gi},
+	}
+
+	for name, test := range tests {
+		t.Run(name, func(t *testing.T) {
+			assert.Equal(t, test.expected, getRoundedCapacity(test.input))
+		})
+	}
+}