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restorer: implement same-file tracking and cloning ("reflinks")

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Note that "cloning" means either true block cloning via `ioctl(FICLONE)`
or any kind of local copy in general via fallback to `io.Copy()`.

TBD:
- fallback to restoring a file normally if it could not be cloned
- track all potential cloning sources for each file (every copy that was
  restored rather than cloned) and try to clone from each copy in turn
  (Why: imagine a set of duplicate files being restored N:M to a set of
   distinct filesystems or subvolumes or datasets, such that some pairs
   can be used as operands to a block cloning operation and some cannot)
- progress reporting (report how much space we have saved, or not)

Non-goals:
- cloning individual blobs via `ioctl(FICLONERANGE)`
  (Why: this is not going to work very well, if at all, due to blobs not
   being aligned to any kind of a fundamental block size, _and_ this
   will impact cloning entire files unless the latter is special-cased,
   which is exactly what is being done here.)
This commit is contained in:
Ivan Shapovalov 2024-11-30 14:35:02 +04:00
parent 111efa211d
commit afeca99aef
1 changed files with 39 additions and 0 deletions
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39
internal/restorer/restorer.go
View file

@ -316,6 +316,24 @@ func (res *Restorer) restoreHardlinkAt(node *restic.Node, target, path, location
return res.restoreNodeMetadataTo(node, path, location)
}
func (res *Restorer) restoreReflink(node *restic.Node, target, path, location string) error {
cloned := true
if !res.opts.DryRun {
var err error
if err = fs.Remove(path); err != nil && !errors.Is(err, os.ErrNotExist) {
return errors.Wrap(err, "RemoveNode")
}
cloned, err = fs.Clone(target, path)
if err != nil {
return errors.WithStack(err)
}
}
res.opts.Progress.AddProgress(location, restoreui.ActionFileRestored, node.Size, node.Size)
// reflinked files *do* have separate metadata
return res.restoreNodeMetadataTo(node, path, location)
}
func (res *Restorer) ensureDir(target string) error {
if res.opts.DryRun {
return nil
@ -358,6 +376,7 @@ func (res *Restorer) RestoreTo(ctx context.Context, dst string) (uint64, error)
}
idx := NewHardlinkIndex[string]()
refIdx := NewReflinkIndex()
filerestorer := newFileRestorer(dst, res.repo.LoadBlobsFromPack, res.repo.LookupBlob,
res.repo.Connections(), res.opts.Sparse, res.opts.Delete, res.repo.StartWarmup, res.opts.Progress)
filerestorer.Error = res.Error
@ -397,6 +416,16 @@ func (res *Restorer) RestoreTo(ctx context.Context, dst string) (uint64, error)
idx.Add(node.Inode, node.DeviceID, location)
}
// do not bother reflinking empty files
if res.opts.Reflinks && node.Size > 0 {
refOrig, refIsOrig := refIdx.Put(location, node.Content)
if !refIsOrig {
debug.Log("reflink (deferring): orig=%s, link=%s", refOrig, location)
res.opts.Progress.AddFile(node.Size)
return nil
}
}
buf, err = res.withOverwriteCheck(ctx, node, target, location, false, buf, func(updateMetadataOnly bool, matches *fileState) error {
if updateMetadataOnly {
res.opts.Progress.AddSkippedFile(location, node.Size)
@ -453,6 +482,16 @@ func (res *Restorer) RestoreTo(ctx context.Context, dst string) (uint64, error)
return err
}
if res.opts.Reflinks && node.Size > 0 {
if orig, hasOrig := refIdx.Get(node.Content); hasOrig && orig != location {
debug.Log("reflink (restoring): orig=%s, link=%s", orig, location)
_, err := res.withOverwriteCheck(ctx, node, target, location, false, nil, func(_ bool, _ *fileState) error {
return res.restoreReflink(node, filerestorer.targetPath(orig), target, location)
})
return err
}
}
if _, ok := res.hasRestoredFile(location); ok {
return res.restoreNodeMetadataTo(node, target, location)
}