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snapshots: refactor metastore transaction

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Signed-off-by: Junyu Liu <ljyngup@gmail.com>
This commit is contained in:
iyear
2023-01-04 19:05:52 +08:00
parent a0b8401ea9
commit 9df5a1714d
3 changed files with 330 additions and 383 deletions
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276
snapshots/windows/windows.go
View File

@@ -110,44 +110,40 @@ func NewSnapshotter(root string) (snapshots.Snapshotter, error) {
//
// Should be used for parent resolution, existence checks and to discern
// the kind of snapshot.
func (s *snapshotter) Stat(ctx context.Context, key string) (snapshots.Info, error) {
ctx, t, err := s.ms.TransactionContext(ctx, false)
func (s *snapshotter) Stat(ctx context.Context, key string) (info snapshots.Info, err error) {
err = s.ms.WithTransaction(ctx, false, func(ctx context.Context) error {
_, info, _, err = storage.GetInfo(ctx, key)
return err
})
if err != nil {
return snapshots.Info{}, err
}
defer t.Rollback()
_, info, _, err := storage.GetInfo(ctx, key)
return info, err
}
func (s *snapshotter) Update(ctx context.Context, info snapshots.Info, fieldpaths ...string) (snapshots.Info, error) {
ctx, t, err := s.ms.TransactionContext(ctx, true)
if err != nil {
return snapshots.Info{}, err
}
defer t.Rollback()
info, err = storage.UpdateInfo(ctx, info, fieldpaths...)
if err != nil {
return snapshots.Info{}, err
}
if err := t.Commit(); err != nil {
return snapshots.Info{}, err
}
return info, nil
}
func (s *snapshotter) Usage(ctx context.Context, key string) (snapshots.Usage, error) {
ctx, t, err := s.ms.TransactionContext(ctx, false)
func (s *snapshotter) Update(ctx context.Context, info snapshots.Info, fieldpaths ...string) (_ snapshots.Info, err error) {
err = s.ms.WithTransaction(ctx, true, func(ctx context.Context) error {
info, err = storage.UpdateInfo(ctx, info, fieldpaths...)
return err
})
if err != nil {
return snapshots.Usage{}, err
return snapshots.Info{}, err
}
id, info, usage, err := storage.GetInfo(ctx, key)
t.Rollback() // transaction no longer needed at this point.
return info, nil
}
func (s *snapshotter) Usage(ctx context.Context, key string) (usage snapshots.Usage, err error) {
var (
id string
info snapshots.Info
)
err = s.ms.WithTransaction(ctx, false, func(ctx context.Context) error {
id, info, usage, err = storage.GetInfo(ctx, key)
return err
})
if err != nil {
return snapshots.Usage{}, err
}
@@ -177,115 +173,113 @@ func (s *snapshotter) View(ctx context.Context, key, parent string, opts ...snap
// called on an read-write or readonly transaction.
//
// This can be used to recover mounts after calling View or Prepare.
func (s *snapshotter) Mounts(ctx context.Context, key string) ([]mount.Mount, error) {
ctx, t, err := s.ms.TransactionContext(ctx, false)
func (s *snapshotter) Mounts(ctx context.Context, key string) (_ []mount.Mount, err error) {
var snapshot storage.Snapshot
err = s.ms.WithTransaction(ctx, false, func(ctx context.Context) error {
snapshot, err = storage.GetSnapshot(ctx, key)
if err != nil {
return fmt.Errorf("failed to get snapshot mount: %w", err)
}
return nil
})
if err != nil {
return nil, err
}
defer t.Rollback()
snapshot, err := storage.GetSnapshot(ctx, key)
if err != nil {
return nil, fmt.Errorf("failed to get snapshot mount: %w", err)
}
return s.mounts(snapshot), nil
}
func (s *snapshotter) Commit(ctx context.Context, name, key string, opts ...snapshots.Opt) (retErr error) {
ctx, t, err := s.ms.TransactionContext(ctx, true)
if err != nil {
return err
}
defer func() {
if retErr != nil {
if rerr := t.Rollback(); rerr != nil {
log.G(ctx).WithError(rerr).Warn("failed to rollback transaction")
}
return s.ms.WithTransaction(ctx, true, func(ctx context.Context) error {
// grab the existing id
id, _, _, err := storage.GetInfo(ctx, key)
if err != nil {
return fmt.Errorf("failed to get storage info for %s: %w", key, err)
}
}()
// grab the existing id
id, _, _, err := storage.GetInfo(ctx, key)
if err != nil {
return fmt.Errorf("failed to get storage info for %s: %w", key, err)
}
snapshot, err := storage.GetSnapshot(ctx, key)
if err != nil {
return err
}
path := s.getSnapshotDir(id)
// If (windowsDiff).Apply was used to populate this layer, then it's already in the 'committed' state.
// See createSnapshot below for more details
if !strings.Contains(key, snapshots.UnpackKeyPrefix) {
if err := s.convertScratchToReadOnlyLayer(ctx, snapshot, path); err != nil {
snapshot, err := storage.GetSnapshot(ctx, key)
if err != nil {
return err
}
}
usage, err := fs.DiskUsage(ctx, path)
if err != nil {
return fmt.Errorf("failed to collect disk usage of snapshot storage: %s: %w", path, err)
}
path := s.getSnapshotDir(id)
if _, err := storage.CommitActive(ctx, key, name, snapshots.Usage(usage), opts...); err != nil {
return fmt.Errorf("failed to commit snapshot: %w", err)
}
return t.Commit()
// If (windowsDiff).Apply was used to populate this layer, then it's already in the 'committed' state.
// See createSnapshot below for more details
if !strings.Contains(key, snapshots.UnpackKeyPrefix) {
if err := s.convertScratchToReadOnlyLayer(ctx, snapshot, path); err != nil {
return err
}
}
usage, err := fs.DiskUsage(ctx, path)
if err != nil {
return fmt.Errorf("failed to collect disk usage of snapshot storage: %s: %w", path, err)
}
if _, err := storage.CommitActive(ctx, key, name, snapshots.Usage(usage), opts...); err != nil {
return fmt.Errorf("failed to commit snapshot: %w", err)
}
return nil
})
}
// Remove abandons the transaction identified by key. All resources
// associated with the key will be removed.
func (s *snapshotter) Remove(ctx context.Context, key string) error {
ctx, t, err := s.ms.TransactionContext(ctx, true)
var (
renamed, path, renamedID string
restore bool
)
err := s.ms.WithTransaction(ctx, true, func(ctx context.Context) error {
id, _, err := storage.Remove(ctx, key)
if err != nil {
return fmt.Errorf("failed to remove: %w", err)
}
path = s.getSnapshotDir(id)
renamedID = "rm-" + id
renamed = s.getSnapshotDir(renamedID)
if err = os.Rename(path, renamed); err != nil && !os.IsNotExist(err) {
if !os.IsPermission(err) {
return err
}
// If permission denied, it's possible that the scratch is still mounted, an
// artifact after a hard daemon crash for example. Worth a shot to try deactivating it
// before retrying the rename.
var (
home, layerID = filepath.Split(path)
di = hcsshim.DriverInfo{
HomeDir: home,
}
)
if deactivateErr := hcsshim.DeactivateLayer(di, layerID); deactivateErr != nil {
return fmt.Errorf("failed to deactivate layer following failed rename: %s: %w", deactivateErr, err)
}
if renameErr := os.Rename(path, renamed); renameErr != nil && !os.IsNotExist(renameErr) {
return fmt.Errorf("second rename attempt following detach failed: %s: %w", renameErr, err)
}
}
restore = true
return nil
})
if err != nil {
if restore { // failed to commit
if err1 := os.Rename(renamed, path); err1 != nil {
// May cause inconsistent data on disk
log.G(ctx).WithError(err1).WithField("path", renamed).Error("Failed to rename after failed commit")
}
}
return err
}
defer t.Rollback()
id, _, err := storage.Remove(ctx, key)
if err != nil {
return fmt.Errorf("failed to remove: %w", err)
}
path := s.getSnapshotDir(id)
renamedID := "rm-" + id
renamed := s.getSnapshotDir(renamedID)
if err := os.Rename(path, renamed); err != nil && !os.IsNotExist(err) {
if !os.IsPermission(err) {
return err
}
// If permission denied, it's possible that the scratch is still mounted, an
// artifact after a hard daemon crash for example. Worth a shot to try deactivating it
// before retrying the rename.
var (
home, layerID = filepath.Split(path)
di = hcsshim.DriverInfo{
HomeDir: home,
}
)
if deactivateErr := hcsshim.DeactivateLayer(di, layerID); deactivateErr != nil {
return fmt.Errorf("failed to deactivate layer following failed rename: %s: %w", deactivateErr, err)
}
if renameErr := os.Rename(path, renamed); renameErr != nil && !os.IsNotExist(renameErr) {
return fmt.Errorf("second rename attempt following detach failed: %s: %w", renameErr, err)
}
}
if err := t.Commit(); err != nil {
if err1 := os.Rename(renamed, path); err1 != nil {
// May cause inconsistent data on disk
log.G(ctx).WithError(err1).WithField("path", renamed).Error("Failed to rename after failed commit")
}
return fmt.Errorf("failed to commit: %w", err)
}
if err := hcsshim.DestroyLayer(s.info, renamedID); err != nil {
if err = hcsshim.DestroyLayer(s.info, renamedID); err != nil {
// Must be cleaned up, any "rm-*" could be removed if no active transactions
log.G(ctx).WithError(err).WithField("path", renamed).Warnf("Failed to remove root filesystem")
}
@@ -295,13 +289,9 @@ func (s *snapshotter) Remove(ctx context.Context, key string) error {
// Walk the committed snapshots.
func (s *snapshotter) Walk(ctx context.Context, fn snapshots.WalkFunc, fs ...string) error {
ctx, t, err := s.ms.TransactionContext(ctx, false)
if err != nil {
return err
}
defer t.Rollback()
return storage.WalkInfo(ctx, fn, fs...)
return s.ms.WithTransaction(ctx, false, func(ctx context.Context) error {
return storage.WalkInfo(ctx, fn, fs...)
})
}
// Close closes the snapshotter
@@ -351,24 +341,23 @@ func (s *snapshotter) getSnapshotDir(id string) string {
return filepath.Join(s.root, "snapshots", id)
}
func (s *snapshotter) createSnapshot(ctx context.Context, kind snapshots.Kind, key, parent string, opts []snapshots.Opt) ([]mount.Mount, error) {
ctx, t, err := s.ms.TransactionContext(ctx, true)
if err != nil {
return nil, err
}
defer t.Rollback()
func (s *snapshotter) createSnapshot(ctx context.Context, kind snapshots.Kind, key, parent string, opts []snapshots.Opt) (_ []mount.Mount, err error) {
var newSnapshot storage.Snapshot
err = s.ms.WithTransaction(ctx, true, func(ctx context.Context) error {
newSnapshot, err = storage.CreateSnapshot(ctx, kind, key, parent, opts...)
if err != nil {
return fmt.Errorf("failed to create snapshot: %w", err)
}
newSnapshot, err := storage.CreateSnapshot(ctx, kind, key, parent, opts...)
if err != nil {
return nil, fmt.Errorf("failed to create snapshot: %w", err)
}
if kind != snapshots.KindActive {
return nil
}
if kind == snapshots.KindActive {
log.G(ctx).Debug("createSnapshot active")
// Create the new snapshot dir
snDir := s.getSnapshotDir(newSnapshot.ID)
if err := os.MkdirAll(snDir, 0700); err != nil {
return nil, err
if err = os.MkdirAll(snDir, 0700); err != nil {
return err
}
// IO/disk space optimization
@@ -391,7 +380,7 @@ func (s *snapshotter) createSnapshot(ctx context.Context, kind snapshots.Kind, k
sizeInGB, err := strconv.ParseUint(sizeGBstr, 10, 32)
if err != nil {
return nil, fmt.Errorf("failed to parse label %q=%q: %w", rootfsSizeInGBLabel, sizeGBstr, err)
return fmt.Errorf("failed to parse label %q=%q: %w", rootfsSizeInGBLabel, sizeGBstr, err)
}
sizeInBytes = sizeInGB * 1024 * 1024 * 1024
}
@@ -400,7 +389,7 @@ func (s *snapshotter) createSnapshot(ctx context.Context, kind snapshots.Kind, k
if sizeBytesStr, ok := snapshotInfo.Labels[rootfsSizeInBytesLabel]; ok {
sizeInBytes, err = strconv.ParseUint(sizeBytesStr, 10, 64)
if err != nil {
return nil, fmt.Errorf("failed to parse label %q=%q: %w", rootfsSizeInBytesLabel, sizeBytesStr, err)
return fmt.Errorf("failed to parse label %q=%q: %w", rootfsSizeInBytesLabel, sizeBytesStr, err)
}
}
@@ -411,18 +400,19 @@ func (s *snapshotter) createSnapshot(ctx context.Context, kind snapshots.Kind, k
// This has to be run first to avoid clashing with the containers sandbox.vhdx.
if makeUVMScratch {
if err := s.createUVMScratchLayer(ctx, snDir, parentLayerPaths); err != nil {
return nil, fmt.Errorf("failed to make UVM's scratch layer: %w", err)
if err = s.createUVMScratchLayer(ctx, snDir, parentLayerPaths); err != nil {
return fmt.Errorf("failed to make UVM's scratch layer: %w", err)
}
}
if err := s.createScratchLayer(ctx, snDir, parentLayerPaths, sizeInBytes); err != nil {
return nil, fmt.Errorf("failed to create scratch layer: %w", err)
if err = s.createScratchLayer(ctx, snDir, parentLayerPaths, sizeInBytes); err != nil {
return fmt.Errorf("failed to create scratch layer: %w", err)
}
}
}
if err := t.Commit(); err != nil {
return nil, fmt.Errorf("commit failed: %w", err)
return nil
})
if err != nil {
return nil, err
}
return s.mounts(newSnapshot), nil