Few small changes to facilitate testing

Signed-off-by: David Cassany <dcassany@suse.com>

pkg/snapshotter/btrfs-backend.go

@@ -107,7 +107,8 @@ func (d *Date) UnmarshalXML(dec *xml.Decoder, start xml.StartElement) error {
 
 type btrfsBackend struct {
 	cfg          *types.Config
-	stat         backendStat
+	currentID    int
+	activeID     int
 	maxSnapshots int
 }
 
@@ -119,15 +120,11 @@ func newBtrfsBackend(cfg *types.Config, maxSnapshots int) *btrfsBackend {
 // Probe tests the given device and returns the found state as a backendStat struct
 func (b *btrfsBackend) Probe(device string, mountpoint string) (backendStat, error) {
 	var rootVolume, snapshotsVolume bool
-
-	// Do not compute it again if it was already done in advance
-	if b.stat.rootDir != "" && b.stat.stateMount != "" {
-		return b.stat, nil
-	}
+	var stat backendStat
 
 	volumes, err := b.getSubvolumes(mountpoint)
 	if err != nil {
-		return b.stat, err
+		return stat, err
 	}
 
 	b.cfg.Logger.Debugf(
@@ -145,10 +142,10 @@ func (b *btrfsBackend) Probe(device string, mountpoint string) (backendStat, err
 	if rootVolume && snapshotsVolume {
 		id, err := b.getActiveSnapshot(mountpoint)
 		if err != nil {
-			return b.stat, err
+			return stat, err
 		}
 		if id > 0 {
-			b.stat.activeID = id
+			b.activeID = id
 		}
 	}
 
@@ -157,17 +154,19 @@ func (b *btrfsBackend) Probe(device string, mountpoint string) (backendStat, err
 	if elemental.IsPassiveMode(*b.cfg) || elemental.IsActiveMode(*b.cfg) {
 		rootDir, stateMount, currentID, err := b.findStateMount(device)
 		if err != nil {
-			return b.stat, err
+			return stat, err
 		}
-		b.stat.rootDir = rootDir
-		b.stat.stateMount = stateMount
-		b.stat.currentID = currentID
-		return b.stat, nil
+		stat.RootDir = rootDir
+		stat.StateMount = stateMount
+		stat.CurrentID, b.currentID = currentID, currentID
+		stat.ActiveID = b.activeID
+		return stat, nil
 	}
 
-	b.stat.rootDir = mountpoint
-	b.stat.stateMount = mountpoint
-	return b.stat, nil
+	stat.RootDir = mountpoint
+	stat.StateMount = mountpoint
+	stat.ActiveID = b.activeID
+	return stat, nil
 }
 
 // InitBrfsPartition is the method required to create snapshots structure on just formated partition
@@ -305,8 +304,8 @@ func (b btrfsBackend) ListSnapshots(rootDir string) (snapshotsList, error) {
 	}
 
 	snaps.IDs = subvolumesListToSnapshotsIDs(list)
-	snaps.activeID = activeID
-	b.stat.activeID = activeID
+	snaps.ActiveID = activeID
+	b.activeID = activeID
 	return snaps, nil
 }
 
@@ -315,7 +314,7 @@ func (b btrfsBackend) DeleteSnapshot(rootDir string, id int) error {
 	if id <= 0 {
 		return fmt.Errorf("invalid id, should be higher than zero")
 	}
-	if id == b.stat.currentID {
+	if id == b.currentID {
 		return fmt.Errorf("invalid id, cannot delete current snapshot")
 	}
 	cmdOut, err := b.cfg.Runner.Run("btrfs", "subvolume", "delete", filepath.Join(rootDir, fmt.Sprintf(snapshotPathTmpl, id)))
@@ -344,7 +343,7 @@ func (b btrfsBackend) SnapshotsCleanup(rootDir string) error {
 	if snapsToDelete > 0 {
 		slices.Sort(list.IDs)
 		for i := range snapsToDelete {
-			if list.IDs[i] == b.stat.currentID {
+			if list.IDs[i] == b.currentID {
 				b.cfg.Logger.Warnf("current snapshot '%d' can't be cleaned up, stopping", list.IDs[i])
 				break
 			}
@@ -499,7 +498,7 @@ func (b btrfsBackend) clearInProgressMetadata(rootDir string, id int) error {
 
 // computeNewID defines the next available snapshot ID
 func (b btrfsBackend) computeNewID(rootDir string) (int, error) {
-	if b.stat.activeID == 0 {
+	if b.activeID == 0 {
 		// If there is no active snapshot we assume this will be the first one
 		return 1, nil
 	}

pkg/snapshotter/btrfs.go

@@ -63,14 +63,14 @@ type subvolumeBackend interface {
 
 type snapshotsList struct {
 	IDs      []int
-	activeID int
+	ActiveID int
 }
 
 type backendStat struct {
-	activeID   int
-	currentID  int
-	rootDir    string
-	stateMount string
+	ActiveID   int
+	CurrentID  int
+	RootDir    string
+	StateMount string
 }
 
 type Btrfs struct {
@@ -105,21 +105,23 @@ func newBtrfsSnapshotter(cfg types.Config, snapCfg types.SnapshotterConfig, boot
 			return nil, fmt.Errorf("%s", msg)
 		}
 	}
-	var backend subvolumeBackend
-	if btrfsCfg.Snapper {
-		backend = newSnapperBackend(&cfg, snapCfg.MaxSnaps)
-	} else {
-		backend = newBtrfsBackend(&cfg, snapCfg.MaxSnaps)
-	}
 	return &Btrfs{
 		cfg: cfg, snapshotterCfg: snapCfg,
 		btrfsCfg: *btrfsCfg, bootloader: bootloader,
 		snapshotsUmount: func() error { return nil },
 		snapshotsMount:  func() error { return nil },
-		backend:         backend,
+		backend:         NewSubvolumeBackend(&cfg, *btrfsCfg, snapCfg.MaxSnaps),
 	}, nil
 }
 
+// NewSubvolumeBackend returns an instance of a subvolume backend
+func NewSubvolumeBackend(cfg *types.Config, bCfg types.BtrfsConfig, maxSnaps int) subvolumeBackend {
+	if bCfg.Snapper {
+		return newSnapperBackend(cfg, maxSnaps)
+	}
+	return newBtrfsBackend(cfg, maxSnaps)
+}
+
 // InitSnapshotter initiates the snapshotter to the given root directory. This method includes the logic to create
 // required subvolmes to handle snapshots as snapper does.
 func (b *Btrfs) InitSnapshotter(state *types.Partition, efiDir string) error {
@@ -314,7 +316,7 @@ func (b *Btrfs) GetSnapshots() (snapshots []int, err error) {
 		if err != nil {
 			return nil, err
 		}
-		b.activeSnapshotID = snapList.activeID
+		b.activeSnapshotID = snapList.ActiveID
 		return snapList.IDs, err
 	}
 
@@ -352,10 +354,10 @@ func (b *Btrfs) isInitiated(state *types.Partition) (bool, error) {
 	if err != nil {
 		return false, err
 	}
-	b.activeSnapshotID = bStat.activeID
-	b.rootDir = bStat.rootDir
-	state.MountPoint = bStat.stateMount
-	return bStat.activeID > 0, nil
+	b.activeSnapshotID = bStat.ActiveID
+	b.rootDir = bStat.RootDir
+	state.MountPoint = bStat.StateMount
+	return bStat.ActiveID > 0, nil
 }
 
 // getPassiveSnapshots returns a list of the available snapshots
@@ -437,7 +439,7 @@ func (b *Btrfs) remountStatePartition(state *types.Partition) error {
 	return err
 }
 
-// mountSnapshotsSubvolumeInSnapshot mounts the snapshots subvolume inside the active snapshot tree
+// mountSnapshotsSubvolumeInSnapshot mounts the snapshots subvolume inside the given snapshot tree
 func (b *Btrfs) mountSnapshotsSubvolumeInSnapshot(root, device string, snapshotID int) error {
 	var mountpoint, subvol string
 

pkg/snapshotter/snapper-backend.go

@@ -38,14 +38,15 @@ var _ subvolumeBackend = (*snapperBackend)(nil)
 
 type snapperBackend struct {
 	cfg          *types.Config
-	stat         backendStat
+	currentID    int
+	activeID     int
 	btrfs        *btrfsBackend
 	maxSnapshots int
 }
 
 // newSnapperBackend creates a new instance for of the snapper backend
 func newSnapperBackend(cfg *types.Config, maxSnapshots int) *snapperBackend {
-	// snapper backend embeds an instance of a btrfs backend to handle fill the gap for the
+	// snapper backend embeds an instance of a btrfs backend to fill the gap for the
 	// operatons that snapper can't entirely handle.
 	return &snapperBackend{cfg: cfg, maxSnapshots: maxSnapshots, btrfs: newBtrfsBackend(cfg, maxSnapshots)}
 }
@@ -54,9 +55,9 @@ func newSnapperBackend(cfg *types.Config, maxSnapshots int) *snapperBackend {
 func (s *snapperBackend) Probe(device, mountpoint string) (backendStat, error) {
 	stat, err := s.btrfs.Probe(device, mountpoint)
 	if err != nil {
-		return s.stat, err
+		return stat, err
 	}
-	s.stat = stat
+	s.activeID, s.currentID = stat.ActiveID, stat.CurrentID
 	return stat, nil
 }
 
@@ -116,7 +117,7 @@ func (s snapperBackend) CommitSnapshot(rootDir string, snapshot *types.Snapshot)
 		return err
 	}
 
-	if s.stat.activeID == 0 && s.stat.currentID == 0 {
+	if s.activeID == 0 && s.currentID == 0 {
 		// Snapper does not support modifying a snapshot from a host not having a configured snapper
 		// and this is the case for the installation media
 		return s.btrfs.CommitSnapshot(rootDir, snapshot)
@@ -162,18 +163,18 @@ func (s snapperBackend) ListSnapshots(rootDir string) (snapshotsList, error) {
 			}
 			ids = append(ids, id)
 			if match[2] == "yes" {
-				sl.activeID = id
+				sl.ActiveID = id
 			}
 		}
 	}
 	sl.IDs = ids
-	s.stat.activeID = sl.activeID
+	s.activeID = sl.ActiveID
 	return sl, nil
 }
 
 // DeleteSnapshot deletes the given snapshot
 func (s snapperBackend) DeleteSnapshot(rootDir string, id int) error {
-	if s.stat.activeID == 0 && s.stat.currentID == 0 {
+	if s.activeID == 0 && s.currentID == 0 {
 		// With snapper is not possible to delete any snapshot without an active one
 		return s.btrfs.DeleteSnapshot(rootDir, id)
 	}
@@ -202,8 +203,8 @@ func (s snapperBackend) SnapshotsCleanup(rootDir string) error {
 // over the actual "/" root
 func (s snapperBackend) rootArgs(rootDir string) []string {
 	args := []string{}
-	if rootDir != "/" && s.stat.currentID == 0 {
-		args = []string{"--no-dbus", "--root", filepath.Join(rootDir, fmt.Sprintf(snapshotPathTmpl, s.stat.activeID))}
+	if rootDir != "/" && s.currentID == 0 && s.activeID > 0 {
+		args = []string{"--no-dbus", "--root", filepath.Join(rootDir, fmt.Sprintf(snapshotPathTmpl, s.activeID))}
 	} else if rootDir != "/" {
 		args = []string{"--no-dbus", "--root", rootDir}
 	}