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Implement btrfs usage

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Implements btrfs usage using a double walking diff and
counting the result. Walking gives the most accurate
count and includes inode usage.

Signed-off-by: Derek McGowan <derek@mcgstyle.net>
This commit is contained in:
Derek McGowan
2017-12-04 10:48:22 -08:00
parent f6df9f6632
commit 3bc4e69ba1
4 changed files with 120 additions and 17 deletions
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55
snapshots/btrfs/btrfs.go
View File

@@ -10,6 +10,7 @@ import (
"strings"
"github.com/containerd/btrfs"
"github.com/containerd/containerd/fs"
"github.com/containerd/containerd/log"
"github.com/containerd/containerd/mount"
"github.com/containerd/containerd/platforms"
@@ -128,18 +129,43 @@ func (b *snapshotter) Update(ctx context.Context, info snapshots.Info, fieldpath
// Usage retrieves the disk usage of the top-level snapshot.
func (b *snapshotter) Usage(ctx context.Context, key string) (snapshots.Usage, error) {
panic("not implemented")
return b.usage(ctx, key)
}
// TODO(stevvooe): Btrfs has a quota model where data can be exclusive to a
// snapshot or shared among other resources. We may find that this is the
// correct value to reoprt but the stability of the implementation is under
// question.
//
// In general, this has impact on the model we choose for reporting usage.
// Ideally, the value should allow aggregration. For overlay, this is
// simple since we can scan the diff directory to get a unique value. This
// breaks down when start looking the behavior when data is shared between
// snapshots, such as that for btrfs.
func (b *snapshotter) usage(ctx context.Context, key string) (snapshots.Usage, error) {
ctx, t, err := b.ms.TransactionContext(ctx, false)
if err != nil {
return snapshots.Usage{}, err
}
id, info, usage, err := storage.GetInfo(ctx, key)
var parentID string
if err == nil && info.Kind == snapshots.KindActive && info.Parent != "" {
parentID, _, _, err = storage.GetInfo(ctx, info.Parent)
}
t.Rollback() // transaction no longer needed at this point.
if err != nil {
return snapshots.Usage{}, err
}
if info.Kind == snapshots.KindActive {
var du fs.Usage
p := filepath.Join(b.root, "active", id)
if parentID != "" {
du, err = fs.DiffUsage(ctx, filepath.Join(b.root, "snapshots", parentID), p)
} else {
du, err = fs.DiskUsage(p)
}
if err != nil {
// TODO(stevvooe): Consider not reporting an error in this case.
return snapshots.Usage{}, err
}
usage = snapshots.Usage(du)
}
return usage, nil
}
// Walk the committed snapshots.
@@ -238,6 +264,11 @@ func (b *snapshotter) mounts(dir string, s storage.Snapshot) ([]mount.Mount, err
}
func (b *snapshotter) Commit(ctx context.Context, name, key string, opts ...snapshots.Opt) (err error) {
usage, err := b.usage(ctx, key)
if err != nil {
return errors.Wrap(err, "failed to compute usage")
}
ctx, t, err := b.ms.TransactionContext(ctx, true)
if err != nil {
return err
@@ -250,7 +281,7 @@ func (b *snapshotter) Commit(ctx context.Context, name, key string, opts ...snap
}
}()
id, err := storage.CommitActive(ctx, key, name, snapshots.Usage{}, opts...) // TODO(stevvooe): Resolve a usage value for btrfs
id, err := storage.CommitActive(ctx, key, name, usage, opts...) // TODO(stevvooe): Resolve a usage value for btrfs
if err != nil {
return errors.Wrap(err, "failed to commit")
}