Merge pull request #697 from dmcgowan/snapshot-naive
Update naive driver to use storage package
This commit is contained in:
Stephen Day
GitHub
commit
56972bf915
2 changed files with 234 additions and 156 deletions
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@ -1,117 +1,263 @@
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package naive
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import (
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"fmt"
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"context"
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"io/ioutil"
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"os"
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"path/filepath"
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"github.com/containerd/containerd"
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"github.com/containerd/containerd/fs"
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"github.com/containerd/containerd/log"
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"github.com/containerd/containerd/plugin"
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"github.com/containerd/containerd/snapshot"
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"github.com/containerd/containerd/snapshot/storage"
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"github.com/pkg/errors"
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)
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type Naive struct {
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func init() {
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plugin.Register("snapshot-naive", &plugin.Registration{
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Type: plugin.SnapshotPlugin,
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Init: func(ic *plugin.InitContext) (interface{}, error) {
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return NewSnapshotter(filepath.Join(ic.Root, "snapshot", "naive"))
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},
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})
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}
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type snapshotter struct {
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root string
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// TODO(stevvooe): Very lazy copying from the overlay driver. We'll have to
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// put *all* of this on disk in an easy to access format.
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active map[string]activeNaiveSnapshot
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parents map[string]string // mirror of what is on disk
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ms *storage.MetaStore
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}
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type activeNaiveSnapshot struct {
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parent string
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metadata string
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}
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func NewNaive(root string) (*Naive, error) {
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if err := os.MkdirAll(root, 0777); err != nil {
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// NewSnapshotter returns a Snapshotter which copies layers on the underlying
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// file system. A metadata file is stored under the root.
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func NewSnapshotter(root string) (snapshot.Snapshotter, error) {
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if err := os.MkdirAll(root, 0700); err != nil {
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return nil, err
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}
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ms, err := storage.NewMetaStore(filepath.Join(root, "metadata.db"))
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if err != nil {
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return nil, err
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}
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// TODO(stevvooe): Recover active transactions.
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if err := os.Mkdir(filepath.Join(root, "snapshots"), 0700); err != nil {
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return nil, err
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}
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return &Naive{
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root: root,
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active: make(map[string]activeNaiveSnapshot),
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parents: make(map[string]string),
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return &snapshotter{
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root: root,
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ms: ms,
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}, nil
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}
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// Prepare works per the snapshot specification.
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// Stat returns the info for an active or committed snapshot by name or
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// key.
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//
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// For the naive driver, the data is checked out directly into dst and no
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// mounts are returned.
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func (n *Naive) Prepare(dst, parent string) ([]containerd.Mount, error) {
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metadataRoot, err := ioutil.TempDir(n.root, "active-")
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// Should be used for parent resolution, existence checks and to discern
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// the kind of snapshot.
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func (o *snapshotter) Stat(ctx context.Context, key string) (snapshot.Info, error) {
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ctx, t, err := o.ms.TransactionContext(ctx, false)
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if err != nil {
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return nil, errors.Wrap(err, "failed to created transaction dir")
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return snapshot.Info{}, err
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}
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// TODO(stevvooe): Write in driver metadata so it can be identified,
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// probably part of common manager type.
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if err := ioutil.WriteFile(filepath.Join(metadataRoot, "target"), []byte(dst), 0777); err != nil {
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return nil, errors.Wrap(err, "failed to write target to disk")
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}
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if parent != "" {
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if _, ok := n.parents[parent]; !ok {
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return nil, errors.Wrap(err, "specified parent does not exist")
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}
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if err := ioutil.WriteFile(filepath.Join(metadataRoot, "parent"), []byte(parent), 0777); err != nil {
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return nil, errors.Wrap(err, "error specifying parent")
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}
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// Now, we copy the parent filesystem, just a directory, into dst.
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if err := fs.CopyDir(dst, filepath.Join(parent, "data")); err != nil {
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return nil, errors.Wrap(err, "copying of parent failed")
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}
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}
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n.active[dst] = activeNaiveSnapshot{
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parent: parent,
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metadata: metadataRoot,
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}
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return nil, nil // no mounts!!
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defer t.Rollback()
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return storage.GetInfo(ctx, key)
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}
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// Commit just moves the metadata directory to the diff location.
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func (n *Naive) Commit(diff, dst string) error {
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active, ok := n.active[dst]
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if !ok {
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return errors.Errorf("%v is not an active transaction", dst)
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func (o *snapshotter) Prepare(ctx context.Context, key, parent string) ([]containerd.Mount, error) {
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return o.createActive(ctx, key, parent, false)
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}
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func (o *snapshotter) View(ctx context.Context, key, parent string) ([]containerd.Mount, error) {
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return o.createActive(ctx, key, parent, true)
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}
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// Mounts returns the mounts for the transaction identified by key. Can be
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// called on an read-write or readonly transaction.
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//
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// This can be used to recover mounts after calling View or Prepare.
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func (o *snapshotter) Mounts(ctx context.Context, key string) ([]containerd.Mount, error) {
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ctx, t, err := o.ms.TransactionContext(ctx, false)
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if err != nil {
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return nil, err
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}
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active, err := storage.GetActive(ctx, key)
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t.Rollback()
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if err != nil {
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return nil, errors.Wrap(err, "failed to get active mount")
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}
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return o.mounts(active), nil
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}
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func (o *snapshotter) Commit(ctx context.Context, name, key string) error {
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ctx, t, err := o.ms.TransactionContext(ctx, true)
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if err != nil {
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return err
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}
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if _, err := storage.CommitActive(ctx, key, name); err != nil {
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if rerr := t.Rollback(); rerr != nil {
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log.G(ctx).WithError(rerr).Warn("Failure rolling back transaction")
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}
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return errors.Wrap(err, "failed to commit snapshot")
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}
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return t.Commit()
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}
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// Remove abandons the transaction identified by key. All resources
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// associated with the key will be removed.
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func (o *snapshotter) Remove(ctx context.Context, key string) (err error) {
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ctx, t, err := o.ms.TransactionContext(ctx, true)
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if err != nil {
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return err
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}
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defer func() {
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if err != nil && t != nil {
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if rerr := t.Rollback(); rerr != nil {
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log.G(ctx).WithError(rerr).Warn("Failure rolling back transaction")
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}
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}
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}()
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id, _, err := storage.Remove(ctx, key)
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if err != nil {
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return errors.Wrap(err, "failed to remove")
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}
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// Move the data into our metadata directory, we could probably save disk
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// space if we just saved the diff, but let's get something working.
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if err := fs.CopyDir(filepath.Join(active.metadata, "data"), dst); err != nil {
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return errors.Wrap(err, "copying of parent failed")
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path := o.getSnapshotDir(id)
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renamed := filepath.Join(o.root, "snapshots", "rm-"+id)
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if err := os.Rename(path, renamed); err != nil {
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if !os.IsNotExist(err) {
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return errors.Wrap(err, "failed to rename")
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}
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renamed = ""
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}
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if err := os.Rename(active.metadata, diff); err != nil {
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return errors.Wrap(err, "failed to rename metadata into diff")
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err = t.Commit()
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t = nil
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if err != nil {
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if renamed != "" {
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if err1 := os.Rename(renamed, path); err1 != nil {
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// May cause inconsistent data on disk
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log.G(ctx).WithError(err1).WithField("path", renamed).Errorf("Failed to rename after failed commit")
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}
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}
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return errors.Wrap(err, "failed to commit")
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}
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if renamed != "" {
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if err := os.RemoveAll(renamed); err != nil {
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// Must be cleaned up, any "rm-*" could be removed if no active transactions
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log.G(ctx).WithError(err).WithField("path", renamed).Warnf("Failed to remove root filesystem")
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}
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}
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n.parents[diff] = active.parent
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delete(n.active, dst)
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return nil
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}
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func (n *Naive) Rollback(dst string) error {
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active, ok := n.active[dst]
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if !ok {
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return fmt.Errorf("%q must be an active snapshot", dst)
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// Walk the committed snapshots.
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func (o *snapshotter) Walk(ctx context.Context, fn func(context.Context, snapshot.Info) error) error {
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ctx, t, err := o.ms.TransactionContext(ctx, false)
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if err != nil {
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return err
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}
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defer t.Rollback()
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return storage.WalkInfo(ctx, fn)
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}
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func (o *snapshotter) createActive(ctx context.Context, key, parent string, readonly bool) ([]containerd.Mount, error) {
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var (
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err error
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path, td string
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)
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if !readonly || parent == "" {
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td, err = ioutil.TempDir(filepath.Join(o.root, "snapshots"), "new-")
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if err != nil {
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return nil, errors.Wrap(err, "failed to create temp dir")
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}
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defer func() {
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if err != nil {
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if td != "" {
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if err1 := os.RemoveAll(td); err1 != nil {
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err = errors.Wrapf(err, "remove failed: %v", err1)
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}
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}
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if path != "" {
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if err1 := os.RemoveAll(path); err1 != nil {
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err = errors.Wrapf(err, "failed to remove path: %v", err1)
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}
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}
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}
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}()
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}
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delete(n.active, dst)
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return os.RemoveAll(active.metadata)
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ctx, t, err := o.ms.TransactionContext(ctx, true)
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if err != nil {
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return nil, err
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}
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active, err := storage.CreateActive(ctx, key, parent, readonly)
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if err != nil {
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if rerr := t.Rollback(); rerr != nil {
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log.G(ctx).WithError(rerr).Warn("Failure rolling back transaction")
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}
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return nil, errors.Wrap(err, "failed to create active")
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}
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if td != "" {
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if len(active.ParentIDs) > 0 {
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parent := o.getSnapshotDir(active.ParentIDs[0])
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if err := fs.CopyDir(td, parent); err != nil {
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return nil, errors.Wrap(err, "copying of parent failed")
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}
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}
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path = o.getSnapshotDir(active.ID)
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if err := os.Rename(td, path); err != nil {
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if rerr := t.Rollback(); rerr != nil {
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log.G(ctx).WithError(rerr).Warn("Failure rolling back transaction")
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}
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return nil, errors.Wrap(err, "failed to rename")
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}
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td = ""
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}
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if err := t.Commit(); err != nil {
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return nil, errors.Wrap(err, "commit failed")
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}
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return o.mounts(active), nil
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}
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func (n *Naive) Parent(diff string) string {
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return n.parents[diff]
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func (o *snapshotter) getSnapshotDir(id string) string {
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return filepath.Join(o.root, "snapshots", id)
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}
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func (o *snapshotter) mounts(active storage.Active) []containerd.Mount {
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var (
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roFlag string
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source string
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)
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if active.Readonly {
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roFlag = "ro"
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} else {
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roFlag = "rw"
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}
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if len(active.ParentIDs) == 0 || !active.Readonly {
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source = o.getSnapshotDir(active.ID)
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} else {
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source = o.getSnapshotDir(active.ParentIDs[0])
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}
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return []containerd.Mount{
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{
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Source: source,
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Type: "bind",
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Options: []string{
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roFlag,
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"rbind",
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},
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},
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}
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}
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@ -1,92 +1,24 @@
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package naive
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import (
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"io/ioutil"
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"os"
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"path/filepath"
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"context"
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"testing"
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"github.com/containerd/containerd"
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"github.com/containerd/containerd/snapshot"
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"github.com/containerd/containerd/snapshot/testsuite"
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"github.com/containerd/containerd/testutil"
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)
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func TestSnapshotNaiveBasic(t *testing.T) {
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testutil.RequiresRoot(t)
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tmpDir, err := ioutil.TempDir("", "test-naive-")
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func newSnapshotter(ctx context.Context, root string) (snapshot.Snapshotter, func(), error) {
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snapshotter, err := NewSnapshotter(root)
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if err != nil {
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t.Fatal(err)
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}
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defer os.RemoveAll(tmpDir)
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t.Log(tmpDir)
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root := filepath.Join(tmpDir, "root")
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n, err := NewNaive(root)
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if err != nil {
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t.Fatal(err)
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return nil, nil, err
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}
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preparing := filepath.Join(tmpDir, "preparing")
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if err := os.MkdirAll(preparing, 0777); err != nil {
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t.Fatal(err)
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}
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mounts, err := n.Prepare(preparing, "")
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if err != nil {
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t.Fatal(err)
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}
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if err := containerd.MountAll(mounts, preparing); err != nil {
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t.Fatal(err)
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}
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if err := ioutil.WriteFile(filepath.Join(preparing, "foo"), []byte("foo\n"), 0777); err != nil {
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t.Fatal(err)
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}
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os.MkdirAll(preparing+"/a/b/c", 0755)
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// defer os.Remove(filepath.Join(tmpDir, "foo"))
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committed := filepath.Join(n.root, "committed")
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if err := n.Commit(committed, preparing); err != nil {
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t.Fatal(err)
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}
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if n.Parent(preparing) != "" {
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t.Fatalf("parent of new layer should be empty, got n.Parent(%q) == %q", preparing, n.Parent(preparing))
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}
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next := filepath.Join(tmpDir, "nextlayer")
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if err := os.MkdirAll(next, 0777); err != nil {
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t.Fatal(err)
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}
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mounts, err = n.Prepare(next, committed)
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if err != nil {
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t.Fatal(err)
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}
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if err := containerd.MountAll(mounts, next); err != nil {
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t.Fatal(err)
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}
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if err := ioutil.WriteFile(filepath.Join(next, "bar"), []byte("bar\n"), 0777); err != nil {
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t.Fatal(err)
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}
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// also, change content of foo to bar
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if err := ioutil.WriteFile(filepath.Join(next, "foo"), []byte("bar\n"), 0777); err != nil {
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t.Fatal(err)
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}
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os.RemoveAll(next + "/a/b")
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nextCommitted := filepath.Join(n.root, "committed-next")
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if err := n.Commit(nextCommitted, next); err != nil {
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t.Fatal(err)
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}
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if n.Parent(nextCommitted) != committed {
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t.Fatalf("parent of new layer should be %q, got n.Parent(%q) == %q (%#v)", committed, next, n.Parent(next), n.parents)
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}
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return snapshotter, func() {}, nil
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}
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func TestNaive(t *testing.T) {
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testutil.RequiresRoot(t)
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testsuite.SnapshotterSuite(t, "Naive", newSnapshotter)
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}
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