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Merge pull request #7781 from dcantah/withtransaction

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metastore: Add WithTransaction convenience method
This commit is contained in:
Derek McGowan 2022-12-20 13:42:03 -08:00 committed by GitHub
commit 8b3ed9f4ee
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GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 194 additions and 244 deletions
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65
snapshots/devmapper/snapshotter.go
View File

@ -42,10 +42,13 @@ import (
type fsType string
const (
metadataFileName = "metadata.db"
fsTypeExt4 fsType = "ext4"
fsTypeExt2 fsType = "ext2"
fsTypeXFS fsType = "xfs"
)
const (
metadataFileName = "metadata.db"
devmapperSnapshotFsType = "containerd.io/snapshot/devmapper/fstype"
)
@ -111,7 +114,7 @@ func (s *Snapshotter) Stat(ctx context.Context, key string) (snapshots.Info, err
err error
)
err = s.withTransaction(ctx, false, func(ctx context.Context) error {
err = s.store.WithTransaction(ctx, false, func(ctx context.Context) error {
_, info, _, err = storage.GetInfo(ctx, key)
return err
})
@ -124,7 +127,7 @@ func (s *Snapshotter) Update(ctx context.Context, info snapshots.Info, fieldpath
log.G(ctx).Debugf("update: %s", strings.Join(fieldpaths, ", "))
var err error
err = s.withTransaction(ctx, true, func(ctx context.Context) error {
err = s.store.WithTransaction(ctx, true, func(ctx context.Context) error {
info, err = storage.UpdateInfo(ctx, info, fieldpaths...)
return err
})
@ -143,7 +146,7 @@ func (s *Snapshotter) Usage(ctx context.Context, key string) (snapshots.Usage, e
usage snapshots.Usage
)
err = s.withTransaction(ctx, false, func(ctx context.Context) error {
err = s.store.WithTransaction(ctx, false, func(ctx context.Context) error {
id, info, usage, err = storage.GetInfo(ctx, key)
if err != nil {
return err
@ -183,7 +186,7 @@ func (s *Snapshotter) Mounts(ctx context.Context, key string) ([]mount.Mount, er
err error
)
err = s.withTransaction(ctx, false, func(ctx context.Context) error {
err = s.store.WithTransaction(ctx, false, func(ctx context.Context) error {
snap, err = storage.GetSnapshot(ctx, key)
return err
})
@ -206,7 +209,7 @@ func (s *Snapshotter) Prepare(ctx context.Context, key, parent string, opts ...s
err error
)
err = s.withTransaction(ctx, true, func(ctx context.Context) error {
err = s.store.WithTransaction(ctx, true, func(ctx context.Context) error {
mounts, err = s.createSnapshot(ctx, snapshots.KindActive, key, parent, opts...)
return err
})
@ -223,7 +226,7 @@ func (s *Snapshotter) View(ctx context.Context, key, parent string, opts ...snap
err error
)
err = s.withTransaction(ctx, true, func(ctx context.Context) error {
err = s.store.WithTransaction(ctx, true, func(ctx context.Context) error {
mounts, err = s.createSnapshot(ctx, snapshots.KindView, key, parent, opts...)
return err
})
@ -237,7 +240,7 @@ func (s *Snapshotter) View(ctx context.Context, key, parent string, opts ...snap
func (s *Snapshotter) Commit(ctx context.Context, name, key string, opts ...snapshots.Opt) error {
log.G(ctx).WithFields(logrus.Fields{"name": name, "key": key}).Debug("commit")
return s.withTransaction(ctx, true, func(ctx context.Context) error {
return s.store.WithTransaction(ctx, true, func(ctx context.Context) error {
id, snapInfo, _, err := storage.GetInfo(ctx, key)
if err != nil {
return err
@ -294,7 +297,7 @@ func (s *Snapshotter) Commit(ctx context.Context, name, key string, opts ...snap
func (s *Snapshotter) Remove(ctx context.Context, key string) error {
log.G(ctx).WithField("key", key).Debug("remove")
return s.withTransaction(ctx, true, func(ctx context.Context) error {
return s.store.WithTransaction(ctx, true, func(ctx context.Context) error {
return s.removeDevice(ctx, key)
})
}
@ -330,7 +333,7 @@ func (s *Snapshotter) removeDevice(ctx context.Context, key string) error {
// Walk iterates through all metadata Info for the stored snapshots and calls the provided function for each.
func (s *Snapshotter) Walk(ctx context.Context, fn snapshots.WalkFunc, fs ...string) error {
log.G(ctx).Debug("walk")
return s.withTransaction(ctx, false, func(ctx context.Context) error {
return s.store.WithTransaction(ctx, false, func(ctx context.Context) error {
return storage.WalkInfo(ctx, fn, fs...)
})
}
@ -530,48 +533,6 @@ func (s *Snapshotter) buildMounts(ctx context.Context, snap storage.Snapshot, fi
return mounts
}
// withTransaction wraps fn callback with containerd's meta store transaction.
// If callback returns an error or transaction is not writable, database transaction will be discarded.
func (s *Snapshotter) withTransaction(ctx context.Context, writable bool, fn func(ctx context.Context) error) error {
ctx, trans, err := s.store.TransactionContext(ctx, writable)
if err != nil {
return err
}
var result *multierror.Error
err = fn(ctx)
if err != nil {
result = multierror.Append(result, err)
}
// Always rollback if transaction is not writable
if err != nil || !writable {
if terr := trans.Rollback(); terr != nil {
log.G(ctx).WithError(terr).Error("failed to rollback transaction")
result = multierror.Append(result, fmt.Errorf("rollback failed: %w", terr))
}
} else {
if terr := trans.Commit(); terr != nil {
log.G(ctx).WithError(terr).Error("failed to commit transaction")
result = multierror.Append(result, fmt.Errorf("commit failed: %w", terr))
}
}
if err := result.ErrorOrNil(); err != nil {
log.G(ctx).WithError(err).Debug("snapshotter error")
// Unwrap if just one error
if len(result.Errors) == 1 {
return result.Errors[0]
}
return err
}
return nil
}
// Cleanup cleans up all removed and unused resources
func (s *Snapshotter) Cleanup(ctx context.Context) error {
log.G(ctx).Debug("cleanup")

212
snapshots/overlay/overlay.go
View File

@ -127,15 +127,13 @@ func NewSnapshotter(root string, opts ...Opt) (snapshots.Snapshotter, error) {
//
// Should be used for parent resolution, existence checks and to discern
// the kind of snapshot.
func (o *snapshotter) Stat(ctx context.Context, key string) (snapshots.Info, error) {
ctx, t, err := o.ms.TransactionContext(ctx, false)
if err != nil {
return snapshots.Info{}, err
}
defer t.Rollback()
id, info, _, err := storage.GetInfo(ctx, key)
if err != nil {
return snapshots.Info{}, err
func (o *snapshotter) Stat(ctx context.Context, key string) (info snapshots.Info, err error) {
var id string
if err := o.ms.WithTransaction(ctx, false, func(ctx context.Context) error {
id, info, _, err = storage.GetInfo(ctx, key)
return err
}); err != nil {
return info, err
}
if o.upperdirLabel {
@ -144,47 +142,29 @@ func (o *snapshotter) Stat(ctx context.Context, key string) (snapshots.Info, err
}
info.Labels[upperdirKey] = o.upperPath(id)
}
return info, nil
}
func (o *snapshotter) Update(ctx context.Context, info snapshots.Info, fieldpaths ...string) (snapshots.Info, error) {
ctx, t, err := o.ms.TransactionContext(ctx, true)
func (o *snapshotter) Update(ctx context.Context, info snapshots.Info, fieldpaths ...string) (newInfo snapshots.Info, err error) {
err = o.ms.WithTransaction(ctx, true, func(ctx context.Context) error {
newInfo, err = storage.UpdateInfo(ctx, info, fieldpaths...)
if err != nil {
return snapshots.Info{}, err
}
rollback := true
defer func() {
if rollback {
if rerr := t.Rollback(); rerr != nil {
log.G(ctx).WithError(rerr).Warn("failed to rollback transaction")
}
}
}()
info, err = storage.UpdateInfo(ctx, info, fieldpaths...)
if err != nil {
return snapshots.Info{}, err
return err
}
if o.upperdirLabel {
id, _, _, err := storage.GetInfo(ctx, info.Name)
id, _, _, err := storage.GetInfo(ctx, newInfo.Name)
if err != nil {
return snapshots.Info{}, err
return err
}
if info.Labels == nil {
info.Labels = make(map[string]string)
if newInfo.Labels == nil {
newInfo.Labels = make(map[string]string)
}
info.Labels[upperdirKey] = o.upperPath(id)
newInfo.Labels[upperdirKey] = o.upperPath(id)
}
rollback = false
if err := t.Commit(); err != nil {
return snapshots.Info{}, err
}
return info, nil
return nil
})
return newInfo, err
}
// Usage returns the resources taken by the snapshot identified by key.
@ -193,16 +173,17 @@ func (o *snapshotter) Update(ctx context.Context, info snapshots.Info, fieldpath
// "upper") directory and may take some time.
//
// For committed snapshots, the value is returned from the metadata database.
func (o *snapshotter) Usage(ctx context.Context, key string) (snapshots.Usage, error) {
ctx, t, err := o.ms.TransactionContext(ctx, false)
if err != nil {
return snapshots.Usage{}, err
}
id, info, usage, err := storage.GetInfo(ctx, key)
t.Rollback() // transaction no longer needed at this point.
if err != nil {
return snapshots.Usage{}, err
func (o *snapshotter) Usage(ctx context.Context, key string) (_ snapshots.Usage, err error) {
var (
usage snapshots.Usage
info snapshots.Info
id string
)
if err := o.ms.WithTransaction(ctx, false, func(ctx context.Context) error {
id, info, usage, err = storage.GetInfo(ctx, key)
return err
}); err != nil {
return usage, err
}
if info.Kind == snapshots.KindActive {
@ -212,10 +193,8 @@ func (o *snapshotter) Usage(ctx context.Context, key string) (snapshots.Usage, e
// TODO(stevvooe): Consider not reporting an error in this case.
return snapshots.Usage{}, err
}
usage = snapshots.Usage(du)
}
return usage, nil
}
@ -231,33 +210,22 @@ func (o *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 (o *snapshotter) Mounts(ctx context.Context, key string) ([]mount.Mount, error) {
ctx, t, err := o.ms.TransactionContext(ctx, false)
func (o *snapshotter) Mounts(ctx context.Context, key string) (_ []mount.Mount, err error) {
var s storage.Snapshot
if err := o.ms.WithTransaction(ctx, false, func(ctx context.Context) error {
s, err = storage.GetSnapshot(ctx, key)
if err != nil {
return nil, err
return fmt.Errorf("failed to get active mount: %w", err)
}
s, err := storage.GetSnapshot(ctx, key)
t.Rollback()
if err != nil {
return nil, fmt.Errorf("failed to get active mount: %w", err)
return nil
}); err != nil {
return nil, err
}
return o.mounts(s), nil
}
func (o *snapshotter) Commit(ctx context.Context, name, key string, opts ...snapshots.Opt) error {
ctx, t, err := o.ms.TransactionContext(ctx, true)
if err != nil {
return err
}
defer func() {
if err != nil {
if rerr := t.Rollback(); rerr != nil {
log.G(ctx).WithError(rerr).Warn("failed to rollback transaction")
}
}
}()
return o.ms.WithTransaction(ctx, true, func(ctx context.Context) error {
// grab the existing id
id, _, _, err := storage.GetInfo(ctx, key)
if err != nil {
@ -270,39 +238,17 @@ func (o *snapshotter) Commit(ctx context.Context, name, key string, opts ...snap
}
if _, err = storage.CommitActive(ctx, key, name, snapshots.Usage(usage), opts...); err != nil {
return fmt.Errorf("failed to commit snapshot: %w", err)
return fmt.Errorf("failed to commit snapshot %s: %w", key, err)
}
return t.Commit()
return nil
})
}
// Remove abandons the snapshot identified by key. The snapshot will
// immediately become unavailable and unrecoverable. Disk space will
// be freed up on the next call to `Cleanup`.
func (o *snapshotter) Remove(ctx context.Context, key string) (err error) {
ctx, t, err := o.ms.TransactionContext(ctx, true)
if err != nil {
return err
}
defer func() {
if err != nil {
if rerr := t.Rollback(); rerr != nil {
log.G(ctx).WithError(rerr).Warn("failed to rollback transaction")
}
}
}()
_, _, err = storage.Remove(ctx, key)
if err != nil {
return fmt.Errorf("failed to remove: %w", err)
}
if !o.asyncRemove {
var removals []string
removals, err = o.getCleanupDirectories(ctx)
if err != nil {
return fmt.Errorf("unable to get directories for removal: %w", err)
}
// Remove directories after the transaction is closed, failures must not
// return error since the transaction is committed with the removal
// key no longer available.
@ -315,19 +261,25 @@ func (o *snapshotter) Remove(ctx context.Context, key string) (err error) {
}
}
}()
return o.ms.WithTransaction(ctx, true, func(ctx context.Context) error {
_, _, err = storage.Remove(ctx, key)
if err != nil {
return fmt.Errorf("failed to remove snapshot %s: %w", key, err)
}
return t.Commit()
if !o.asyncRemove {
removals, err = o.getCleanupDirectories(ctx)
if err != nil {
return fmt.Errorf("unable to get directories for removal: %w", err)
}
}
return nil
})
}
// Walk the snapshots.
func (o *snapshotter) Walk(ctx context.Context, fn snapshots.WalkFunc, fs ...string) error {
ctx, t, err := o.ms.TransactionContext(ctx, false)
if err != nil {
return err
}
defer t.Rollback()
return o.ms.WithTransaction(ctx, false, func(ctx context.Context) error {
if o.upperdirLabel {
return storage.WalkInfo(ctx, func(ctx context.Context, info snapshots.Info) error {
id, _, _, err := storage.GetInfo(ctx, info.Name)
@ -342,6 +294,7 @@ func (o *snapshotter) Walk(ctx context.Context, fn snapshots.WalkFunc, fs ...str
}, fs...)
}
return storage.WalkInfo(ctx, fn, fs...)
})
}
// Cleanup cleans up disk resources from removed or abandoned snapshots
@ -360,16 +313,17 @@ func (o *snapshotter) Cleanup(ctx context.Context) error {
return nil
}
func (o *snapshotter) cleanupDirectories(ctx context.Context) ([]string, error) {
func (o *snapshotter) cleanupDirectories(ctx context.Context) (_ []string, err error) {
var cleanupDirs []string
// Get a write transaction to ensure no other write transaction can be entered
// while the cleanup is scanning.
ctx, t, err := o.ms.TransactionContext(ctx, true)
if err != nil {
if err := o.ms.WithTransaction(ctx, true, func(ctx context.Context) error {
cleanupDirs, err = o.getCleanupDirectories(ctx)
return err
}); err != nil {
return nil, err
}
defer t.Rollback()
return o.getCleanupDirectories(ctx)
return cleanupDirs, nil
}
func (o *snapshotter) getCleanupDirectories(ctx context.Context) ([]string, error) {
@ -402,12 +356,11 @@ func (o *snapshotter) getCleanupDirectories(ctx context.Context) ([]string, erro
}
func (o *snapshotter) createSnapshot(ctx context.Context, kind snapshots.Kind, key, parent string, opts []snapshots.Opt) (_ []mount.Mount, err error) {
ctx, t, err := o.ms.TransactionContext(ctx, true)
if err != nil {
return nil, err
}
var (
s storage.Snapshot
td, path string
)
var td, path string
defer func() {
if err != nil {
if td != "" {
@ -424,50 +377,39 @@ func (o *snapshotter) createSnapshot(ctx context.Context, kind snapshots.Kind, k
}
}()
if err := o.ms.WithTransaction(ctx, true, func(ctx context.Context) (err error) {
snapshotDir := filepath.Join(o.root, "snapshots")
td, err = o.prepareDirectory(ctx, snapshotDir, kind)
if err != nil {
if rerr := t.Rollback(); rerr != nil {
log.G(ctx).WithError(rerr).Warn("failed to rollback transaction")
return fmt.Errorf("failed to create prepare snapshot dir: %w", err)
}
return nil, fmt.Errorf("failed to create prepare snapshot dir: %w", err)
}
rollback := true
defer func() {
if rollback {
if rerr := t.Rollback(); rerr != nil {
log.G(ctx).WithError(rerr).Warn("failed to rollback transaction")
}
}
}()
s, err := storage.CreateSnapshot(ctx, kind, key, parent, opts...)
s, err = storage.CreateSnapshot(ctx, kind, key, parent, opts...)
if err != nil {
return nil, fmt.Errorf("failed to create snapshot: %w", err)
return fmt.Errorf("failed to create snapshot: %w", err)
}
if len(s.ParentIDs) > 0 {
st, err := os.Stat(o.upperPath(s.ParentIDs[0]))
if err != nil {
return nil, fmt.Errorf("failed to stat parent: %w", err)
return fmt.Errorf("failed to stat parent: %w", err)
}
stat := st.Sys().(*syscall.Stat_t)
if err := os.Lchown(filepath.Join(td, "fs"), int(stat.Uid), int(stat.Gid)); err != nil {
return nil, fmt.Errorf("failed to chown: %w", err)
return fmt.Errorf("failed to chown: %w", err)
}
}
path = filepath.Join(snapshotDir, s.ID)
if err = os.Rename(td, path); err != nil {
return nil, fmt.Errorf("failed to rename: %w", err)
return fmt.Errorf("failed to rename: %w", err)
}
td = ""
rollback = false
if err = t.Commit(); err != nil {
return nil, fmt.Errorf("commit failed: %w", err)
return nil
}); err != nil {
return nil, err
}
return o.mounts(s), nil

47
snapshots/storage/metastore.go
View File

@ -26,7 +26,9 @@ import (
"fmt"
"sync"
"github.com/containerd/containerd/log"
"github.com/containerd/containerd/snapshots"
"github.com/hashicorp/go-multierror"
bolt "go.etcd.io/bbolt"
)
@ -104,6 +106,51 @@ func (ms *MetaStore) TransactionContext(ctx context.Context, writable bool) (con
return ctx, tx, nil
}
// TransactionCallback represents a callback to be invoked while under a metastore transaction.
type TransactionCallback func(ctx context.Context) error
// WithTransaction is a convenience method to run a function `fn` while holding a meta store transaction.
// If the callback `fn` returns an error or the transaction is not writable, the database transaction will be discarded.
func (ms *MetaStore) WithTransaction(ctx context.Context, writable bool, fn TransactionCallback) error {
ctx, trans, err := ms.TransactionContext(ctx, writable)
if err != nil {
return err
}
var result *multierror.Error
err = fn(ctx)
if err != nil {
result = multierror.Append(result, err)
}
// Always rollback if transaction is not writable
if err != nil || !writable {
if terr := trans.Rollback(); terr != nil {
log.G(ctx).WithError(terr).Error("failed to rollback transaction")
result = multierror.Append(result, fmt.Errorf("rollback failed: %w", terr))
}
} else {
if terr := trans.Commit(); terr != nil {
log.G(ctx).WithError(terr).Error("failed to commit transaction")
result = multierror.Append(result, fmt.Errorf("commit failed: %w", terr))
}
}
if err := result.ErrorOrNil(); err != nil {
log.G(ctx).WithError(err).Debug("snapshotter error")
// Unwrap if just one error
if len(result.Errors) == 1 {
return result.Errors[0]
}
return err
}
return nil
}
// Close closes the metastore and any underlying database connections
func (ms *MetaStore) Close() error {
ms.dbL.Lock()