daemon/graphdriver/zfs fix lint errrors/warnings

Addresses #14756
Signed-off-by: Srini Brahmaroutu <srbrahma@us.ibm.com>

daemon/graphdriver/zfs/zfs.go

@@ -21,7 +21,7 @@ import (
 	"github.com/opencontainers/runc/libcontainer/label"
 )
 
-type ZfsOptions struct {
+type zfsOptions struct {
 	fsName    string
 	mountPath string
 }
@@ -30,12 +30,17 @@ func init() {
 	graphdriver.Register("zfs", Init)
 }
 
+// Logger returns a zfs logger implmentation.
 type Logger struct{}
 
+// Log wraps log message from ZFS driver with a prefix '[zfs]'.
 func (*Logger) Log(cmd []string) {
 	logrus.Debugf("[zfs] %s", strings.Join(cmd, " "))
 }
 
+// Init returns a new ZFS driver.
+// It takes base mount path and a array of options which are represented as key value pairs.
+// Each option is in the for key=value. 'zfs.fsname' is expected to be a valid key in the options.
 func Init(base string, opt []string) (graphdriver.Driver, error) {
 	var err error
 
@@ -101,8 +106,8 @@ func Init(base string, opt []string) (graphdriver.Driver, error) {
 	return graphdriver.NaiveDiffDriver(d), nil
 }
 
-func parseOptions(opt []string) (ZfsOptions, error) {
-	var options ZfsOptions
+func parseOptions(opt []string) (zfsOptions, error) {
+	var options zfsOptions
 	options.fsName = ""
 	for _, option := range opt {
 		key, val, err := parsers.ParseKeyValueOpt(option)
@@ -145,9 +150,10 @@ func lookupZfsDataset(rootdir string) (string, error) {
 	return "", fmt.Errorf("Failed to find zfs dataset mounted on '%s' in /proc/mounts", rootdir)
 }
 
+// Driver holds information about the driver, such as zfs dataset, options and cache.
 type Driver struct {
 	dataset          *zfs.Dataset
-	options          ZfsOptions
+	options          zfsOptions
 	sync.Mutex       // protects filesystem cache against concurrent access
 	filesystemsCache map[string]bool
 }
@@ -156,10 +162,15 @@ func (d *Driver) String() string {
 	return "zfs"
 }
 
+// Cleanup is used to implement graphdriver.ProtoDriver. There is no cleanup required for this driver.
 func (d *Driver) Cleanup() error {
 	return nil
 }
 
+// Status returns information about the ZFS filesystem. It returns a two dimensional array of information
+// such as pool name, dataset name, disk usage, parent quota and compression used.
+// Currently it return 'Zpool', 'Zpool Health', 'Parent Dataset', 'Space Used By Parent',
+// 'Space Available', 'Parent Quota' and 'Compression'.
 func (d *Driver) Status() [][2]string {
 	parts := strings.Split(d.dataset.Name, "/")
 	pool, err := zfs.GetZpool(parts[0])
@@ -189,6 +200,7 @@ func (d *Driver) Status() [][2]string {
 	}
 }
 
+// GetMetadata is used for implementing the graphdriver.ProtoDriver interface. ZFS does not currently have any meta data.
 func (d *Driver) GetMetadata(id string) (map[string]string, error) {
 	return nil, nil
 }
@@ -215,14 +227,17 @@ func (d *Driver) cloneFilesystem(name, parentName string) error {
 	return snapshot.Destroy(zfs.DestroyDeferDeletion)
 }
 
+// ZfsPath returns the filesystem path for the id provided.
 func (d *Driver) ZfsPath(id string) string {
 	return d.options.fsName + "/" + id
 }
 
+// MountPath returns the mounted filesystem path for the id provided.
 func (d *Driver) MountPath(id string) string {
 	return path.Join(d.options.mountPath, "graph", getMountpoint(id))
 }
 
+// Create prepares the dataset and filesystem for the ZFS driver for the given id under the parent.
 func (d *Driver) Create(id string, parent string) error {
 	err := d.create(id, parent)
 	if err == nil {
@@ -261,6 +276,7 @@ func (d *Driver) create(id, parent string) error {
 	return d.cloneFilesystem(name, d.ZfsPath(parent))
 }
 
+// Remove deletes the dataset, filesystem and the cache for the given id.
 func (d *Driver) Remove(id string) error {
 	name := d.ZfsPath(id)
 	dataset := zfs.Dataset{Name: name}
@@ -273,6 +289,7 @@ func (d *Driver) Remove(id string) error {
 	return err
 }
 
+// Get returns the mountpoint for the given id after creating the target directories if necessary.
 func (d *Driver) Get(id, mountLabel string) (string, error) {
 	mountpoint := d.MountPath(id)
 	filesystem := d.ZfsPath(id)
@@ -292,6 +309,7 @@ func (d *Driver) Get(id, mountLabel string) (string, error) {
 	return mountpoint, nil
 }
 
+// Put removes the existing mountpoint for the given id if it exists.
 func (d *Driver) Put(id string) error {
 	mountpoint := d.MountPath(id)
 	logrus.Debugf(`[zfs] unmount("%s")`, mountpoint)
@@ -302,6 +320,7 @@ func (d *Driver) Put(id string) error {
 	return nil
 }
 
+// Exists checks to see if the cache entry exists for the given id.
 func (d *Driver) Exists(id string) bool {
 	return d.filesystemsCache[d.ZfsPath(id)] == true
 }

hack/make/validate-lint

@@ -25,6 +25,7 @@ packages=(
 	daemon/execdriver/native/template
 	daemon/graphdriver/aufs
 	daemon/graphdriver/devmapper
+	daemon/graphdriver/zfs
 	daemon/logger
 	daemon/logger/fluentd
 	daemon/logger/gelf