Revert diff/walking error change

[dmcgowan]

Clarify error scope and create variable for deferring cleanup

Reverts #5551

[theopenlab-ci]

Build succeeded.

• containerd-build-arm64 : SUCCESS in 4m 46s (non-voting)
• containerd-test-arm64 : SUCCESS in 5m 35s (non-voting)
• containerd-integration-test-arm64 : SUCCESS in 22m 07s (non-voting)

[Iceber]

containerd/content/content.go

Line 121 in 6ae9090

// Commit commits the blob (but no roll-back is guaranteed on an error).

Does it mean that we need to perform roll-back after a Commit failure?
eg.

if newReference {
        if abortErr := s.store.Abort(ctx, config.Reference); abortErr != nil {
                log.G(ctx).WithError(abortErr).WithField("ref", config.Reference).Warnf("failed to delete diff upload")
        }
}

---

containerd/content/content.go

Lines 111 to 117 in 6ae9090

	// Writer handles the write of content into a content store
	type Writer interface {
	// Close closes the writer, if the writer has not been
	// committed this allows resuming or aborting.
	// Calling Close on a closed writer will not error.
	io.WriteCloser

Since calling Close on a closed writer will not error, we can set the errOpen after a failed Commit.

if err := cw.Commit(ctx, 0, dgst, commitopts...); err != nil {
        if !errdefs.IsAlreadyExists(err) {
                errOpen = err
                return errors.Wrap(err, "failed to commit")
        }
}

[dmcgowan]

Does it mean that we need to perform roll-back after a Commit failure?

I think in this case calling Abort is the best thing to do. Not aborting on Commit failure allows the caller to try again, but that is not relevant here. I updated the code to just use errOpen on Commit

[theopenlab-ci]

Build succeeded.

• containerd-build-arm64 : NODE_FAILURE in 0s (non-voting)
• containerd-test-arm64 : SUCCESS in 5m 55s (non-voting)
• containerd-integration-test-arm64 : SUCCESS in 24m 00s (non-voting)

[thaJeztah]

LGTM

thanks for the additional comments

[estesp]

LGTM