pkg/storage: report sessions without a node as orphaned

[kobergj]

Problem

Follow-up to #692, which added the orphaned upload session filter. That filter only matches sessions whose node cannot be read:

func (s *OcisSession) IsOrphaned(ctx context.Context) bool {
	_, err := s.Node(ctx)
	return err != nil
}

It does not match a session whose node does not exist at all, because ReadNode deliberately swallows a missing node and reports no error:

attrs, err := n.Xattrs(ctx)
switch {
case metadata.IsNotExist(err):
	return n, nil // swallow not found, the node defaults to exists = false

So err == nil and the session is reported as healthy, even though its upload can never finish.

That leaves a state which cannot be recovered. Cleanup removes the orphaned node before deleting the bin and info files (deliberately — the data must not be destroyed if the revert fails). If it does not get as far as the deletions, the session and its upload payload remain on disk while the node is already gone. The filter then no longer matches them, uploads sessions --clean has nothing to act on, and the leftover bytes can never be collected.

Found while testing the ownCloud Infinite Scale CLI against a deliberately orphaned upload: after cleaning it once, a second --orphaned run reported nothing while the session's .info and payload were still present in uploads/.

Changes

Report a session as orphaned when its node cannot be read or does not exist:

n, err := s.Node(ctx)
return err != nil || n == nil || !n.Exists

The doc comment now spells out both routes into the state and why the second has to be detected through Exists rather than through an error.

No change was needed in revertNode: for a missing node ReadNode returns no error, so ProcessingID fails, the revert is skipped and it returns nil without propagating a size change a second time.

Tests

Adds a test that drives the filter through ListUploadSessions, the way the CLI uses it: a healthy session is not reported, a session whose node has been removed entirely is reported exactly once, and the negated filter reports nothing. It also asserts the underlying premise — that ReadNode on a missing node returns no error with Exists == false — so the test documents why the check is written this way.

Verified that the test fails without the change and passes with it.

🤖 Generated with Claude Code

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