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.go

@@ -37,6 +37,14 @@ import (
 	zfs "github.com/openebs/zfs-localpv/pkg/zfs"
 )
 
+// size constants
+const (
+	MB = 1000 * 1000
+	GB = 1000 * 1000 * 1000
+	Mi = 1024 * 1024
+	Gi = 1024 * 1024 * 1024
+)
+
 // controller is the server implementation
 // for CSI Controller
 type controller struct {
@@ -75,10 +83,26 @@ func sendEventOrIgnore(pvcName, pvName, capacity, stgType, method string) {
 	}
 }
 
+// getRoundedCapacity rounds the capacity on 1024 base
+func getRoundedCapacity(size int64) int64 {
+
+	/*
+	 * 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.
+	 */
+	if size > Gi {
+		return ((size + Gi - 1) / Gi) * Gi
+	}
+
+	// Keeping minimum allocatable size as 1Mi (1024 * 1024)
+	return ((size + Mi - 1) / Mi) * Mi
+}
+
 // CreateZFSVolume create new zfs volume from csi volume request
 func CreateZFSVolume(req *csi.CreateVolumeRequest) (string, error) {
 	volName := req.GetName()
-	size := req.GetCapacityRange().RequiredBytes
+	size := getRoundedCapacity(req.GetCapacityRange().RequiredBytes)
 
 	// parameter keys may be mistyped from the CRD specification when declaring
 	// the storageclass, which kubectl validation will not catch. Because ZFS
@@ -148,7 +172,7 @@ func CreateZFSClone(req *csi.CreateVolumeRequest, snapshot string) (string, erro
 	parameters := req.GetParameters()
 	// lower case keys, cf CreateZFSVolume()
 	pool := helpers.GetInsensitiveParameter(&parameters, "poolname")
-	size := req.GetCapacityRange().RequiredBytes
+	size := getRoundedCapacity(req.GetCapacityRange().RequiredBytes)
 	volsize := strconv.FormatInt(int64(size), 10)
 
 	snapshotID := strings.Split(snapshot, "@")
@@ -208,7 +232,7 @@ func (cs *controller) CreateVolume(
 	parameters := req.GetParameters()
 	// lower case keys, cf CreateZFSVolume()
 	pool := helpers.GetInsensitiveParameter(&parameters, "poolname")
-	size := req.GetCapacityRange().RequiredBytes
+	size := getRoundedCapacity(req.GetCapacityRange().RequiredBytes)
 	contentSource := req.GetVolumeContentSource()
 	pvcName := helpers.GetInsensitiveParameter(&parameters, "csi.storage.k8s.io/pvc/name")
 
@@ -325,7 +349,8 @@ func (cs *controller) ControllerExpandVolume(
 	req *csi.ControllerExpandVolumeRequest,
 ) (*csi.ControllerExpandVolumeResponse, error) {
 
-	updatedSize := req.GetCapacityRange().GetRequiredBytes()
+	/* round off the new size */
+	updatedSize := getRoundedCapacity(req.GetCapacityRange().GetRequiredBytes())
 
 	vol, err := zfs.GetZFSVolume(req.VolumeId)
 	if err != nil {

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))
+		})
+	}
+}