Files
containerd/snapshots/devmapper/dmsetup/dmsetup_test.go
Kern Walster f1d79d33b8 Discard blocks when removing a thin device
dmsetup does not discard blocks when removing a thin device. The unused blocks
are reused by the thin-pool, but will remain allocated in the underlying
device indefinitely. For loop device backed thin-pools, this results in
"lost" disk space in the underlying file system as the blocks remain allocated
in the loop device's backing file.

This change adds an option, discard_blocks, to the devmapper snapshotter which
causes the snapshotter to issue blkdiscard ioctls on the thin device before
removal. With this option enabled, loop device setups will see disk space
return to the underlying filesystem immediately on exiting a container.

Fixes #5691

Signed-off-by: Kern Walster <walster@amazon.com>
2021-07-21 16:06:29 +00:00

212 lines
5.7 KiB
Go

// +build linux
/*
Copyright The containerd 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 dmsetup
import (
"io/ioutil"
"os"
"strings"
"testing"
"github.com/docker/go-units"
"golang.org/x/sys/unix"
"gotest.tools/v3/assert"
is "gotest.tools/v3/assert/cmp"
"github.com/containerd/containerd/mount"
"github.com/containerd/containerd/pkg/testutil"
)
const (
testPoolName = "test-pool"
testDeviceName = "test-device"
deviceID = 1
snapshotID = 2
)
func TestDMSetup(t *testing.T) {
testutil.RequiresRoot(t)
tempDir, err := ioutil.TempDir("", "dmsetup-tests-")
assert.NilError(t, err, "failed to make temp dir for tests")
defer func() {
err := os.RemoveAll(tempDir)
assert.NilError(t, err)
}()
dataImage, loopDataDevice := createLoopbackDevice(t, tempDir)
metaImage, loopMetaDevice := createLoopbackDevice(t, tempDir)
defer func() {
err = mount.DetachLoopDevice(loopDataDevice, loopMetaDevice)
assert.NilError(t, err, "failed to detach loop devices for data image: %s and meta image: %s", dataImage, metaImage)
}()
t.Run("CreatePool", func(t *testing.T) {
err := CreatePool(testPoolName, loopDataDevice, loopMetaDevice, 128)
assert.NilError(t, err, "failed to create thin-pool with %s %s", loopDataDevice, loopMetaDevice)
table, err := Table(testPoolName)
t.Logf("table: %s", table)
assert.NilError(t, err)
assert.Assert(t, strings.HasPrefix(table, "0 32768 thin-pool"))
assert.Assert(t, strings.HasSuffix(table, "128 32768 1 skip_block_zeroing"))
})
t.Run("ReloadPool", func(t *testing.T) {
err := ReloadPool(testPoolName, loopDataDevice, loopMetaDevice, 256)
assert.NilError(t, err, "failed to reload thin-pool")
})
t.Run("CreateDevice", testCreateDevice)
t.Run("CreateSnapshot", testCreateSnapshot)
t.Run("DeleteSnapshot", testDeleteSnapshot)
t.Run("ActivateDevice", testActivateDevice)
t.Run("DeviceStatus", testDeviceStatus)
t.Run("SuspendResumeDevice", testSuspendResumeDevice)
t.Run("DiscardBlocks", testDiscardBlocks)
t.Run("RemoveDevice", testRemoveDevice)
t.Run("RemovePool", func(t *testing.T) {
err = RemoveDevice(testPoolName, RemoveWithForce, RemoveWithRetries)
assert.NilError(t, err, "failed to remove thin-pool")
})
t.Run("Version", testVersion)
}
func testCreateDevice(t *testing.T) {
err := CreateDevice(testPoolName, deviceID)
assert.NilError(t, err, "failed to create test device")
err = CreateDevice(testPoolName, deviceID)
assert.Assert(t, err == unix.EEXIST)
infos, err := Info(testPoolName)
assert.NilError(t, err)
assert.Assert(t, is.Len(infos, 1), "got unexpected number of device infos")
}
func testCreateSnapshot(t *testing.T) {
err := CreateSnapshot(testPoolName, snapshotID, deviceID)
assert.NilError(t, err)
}
func testDeleteSnapshot(t *testing.T) {
err := DeleteDevice(testPoolName, snapshotID)
assert.NilError(t, err, "failed to send delete message")
err = DeleteDevice(testPoolName, snapshotID)
assert.Assert(t, err == unix.ENODATA)
}
func testActivateDevice(t *testing.T) {
err := ActivateDevice(testPoolName, testDeviceName, 1, 1024, "")
assert.NilError(t, err, "failed to activate device")
err = ActivateDevice(testPoolName, testDeviceName, 1, 1024, "")
assert.Equal(t, err, unix.EBUSY)
if _, err := os.Stat("/dev/mapper/" + testDeviceName); err != nil && !os.IsExist(err) {
assert.NilError(t, err, "failed to stat device")
}
list, err := Info(testPoolName)
assert.NilError(t, err)
assert.Assert(t, is.Len(list, 1))
info := list[0]
assert.Equal(t, testPoolName, info.Name)
assert.Assert(t, info.TableLive)
}
func testDeviceStatus(t *testing.T) {
status, err := Status(testDeviceName)
assert.NilError(t, err)
assert.Equal(t, int64(0), status.Offset)
assert.Equal(t, int64(2), status.Length)
assert.Equal(t, "thin", status.Target)
assert.DeepEqual(t, status.Params, []string{"0", "-"})
}
func testSuspendResumeDevice(t *testing.T) {
err := SuspendDevice(testDeviceName)
assert.NilError(t, err)
err = SuspendDevice(testDeviceName)
assert.NilError(t, err)
list, err := Info(testDeviceName)
assert.NilError(t, err)
assert.Assert(t, is.Len(list, 1))
info := list[0]
assert.Assert(t, info.Suspended)
err = ResumeDevice(testDeviceName)
assert.NilError(t, err)
err = ResumeDevice(testDeviceName)
assert.NilError(t, err)
}
func testDiscardBlocks(t *testing.T) {
err := DiscardBlocks(testDeviceName)
assert.NilError(t, err, "failed to discard blocks")
}
func testRemoveDevice(t *testing.T) {
err := RemoveDevice(testPoolName)
assert.Assert(t, err == unix.EBUSY, "removing thin-pool with dependencies shouldn't be allowed")
err = RemoveDevice(testDeviceName, RemoveWithRetries)
assert.NilError(t, err, "failed to remove thin-device")
}
func testVersion(t *testing.T) {
version, err := Version()
assert.NilError(t, err)
assert.Assert(t, version != "")
}
func createLoopbackDevice(t *testing.T, dir string) (string, string) {
file, err := ioutil.TempFile(dir, "dmsetup-tests-")
assert.NilError(t, err)
size, err := units.RAMInBytes("16Mb")
assert.NilError(t, err)
err = file.Truncate(size)
assert.NilError(t, err)
err = file.Close()
assert.NilError(t, err)
imagePath := file.Name()
loopDevice, err := mount.AttachLoopDevice(imagePath)
assert.NilError(t, err)
return imagePath, loopDevice
}