@@ -106,8 +106,8 @@ func (s *TagStore) recursiveLoad(address, tmpImageDir string) error {

 		}

 		// ensure no two downloads of the same layer happen at the same time

-		if ps, err := s.poolAdd("pull", "layer:"+img.ID); err != nil {

-			logrus.Debugf("Image (id: %s) load is already running, waiting: %v", img.ID, err)

+		if ps, found := s.poolAdd("pull", "layer:"+img.ID); found {

+			logrus.Debugf("Image (id: %s) load is already running, waiting", img.ID)

 			ps.Wait(nil, nil)

 			return nil

 		}

@@ -17,20 +17,17 @@ func TestPools(t *testing.T) {

 		pushingPool: make(map[string]*progressreader.ProgressStatus),

 	}

-	if _, err := s.poolAdd("pull", "test1"); err != nil {

-		t.Fatal(err)

-	}

-	if _, err := s.poolAdd("pull", "test2"); err != nil {

-		t.Fatal(err)

+	if _, found := s.poolAdd("pull", "test1"); found {

+		t.Fatal("Expected pull test1 not to be in progress")

 	}

-	if _, err := s.poolAdd("push", "test1"); err == nil || err.Error() != "pull test1 is already in progress" {

-		t.Fatalf("Expected `pull test1 is already in progress`")

+	if _, found := s.poolAdd("pull", "test2"); found {

+		t.Fatal("Expected pull test2 not to be in progress")

 	}

-	if _, err := s.poolAdd("pull", "test1"); err == nil || err.Error() != "pull test1 is already in progress" {

-		t.Fatalf("Expected `pull test1 is already in progress`")

+	if _, found := s.poolAdd("push", "test1"); !found {

+		t.Fatalf("Expected pull test1 to be in progress`")

 	}

-	if _, err := s.poolAdd("wait", "test3"); err == nil || err.Error() != "Unknown pool type" {

-		t.Fatalf("Expected `Unknown pool type`")

+	if _, found := s.poolAdd("pull", "test1"); !found {

+		t.Fatalf("Expected pull test1 to be in progress`")

 	}

 	if err := s.poolRemove("pull", "test2"); err != nil {

 		t.Fatal(err)

@@ -44,7 +41,4 @@ func TestPools(t *testing.T) {

 	if err := s.poolRemove("push", "test1"); err != nil {

 		t.Fatal(err)

 	}

-	if err := s.poolRemove("wait", "test3"); err == nil || err.Error() != "Unknown pool type" {

-		t.Fatalf("Expected `Unknown pool type`")

-	}

 }

@@ -138,8 +138,8 @@ func (p *v1Puller) pullRepository(askedTag string) error {

 			}

 			// ensure no two downloads of the same image happen at the same time

-			ps, err := p.poolAdd("pull", "img:"+img.ID)

-			if err != nil {

+			ps, found := p.poolAdd("pull", "img:"+img.ID)

+			if found {

 				msg := p.sf.FormatProgress(stringid.TruncateID(img.ID), "Layer already being pulled by another client. Waiting.", nil)

 				ps.Wait(out, msg)

 				out.Write(p.sf.FormatProgress(stringid.TruncateID(img.ID), "Download complete", nil))

@@ -155,7 +155,7 @@ func (p *v1Puller) pullRepository(askedTag string) error {

 			ps.Write(p.sf.FormatProgress(stringid.TruncateID(img.ID), fmt.Sprintf("Pulling image (%s) from %s", img.Tag, p.repoInfo.CanonicalName), nil))

 			success := false

-			var lastErr error

+			var lastErr, err error

 			var isDownloaded bool

 			for _, ep := range p.repoInfo.Index.Mirrors {

 				ep += "v1/"

@@ -244,9 +244,9 @@ func (p *v1Puller) pullImage(out io.Writer, imgID, endpoint string, token []stri

 		id := history[i]

 		// ensure no two downloads of the same layer happen at the same time

-		ps, err := p.poolAdd("pull", "layer:"+id)

-		if err != nil {

-			logrus.Debugf("Image (id: %s) pull is already running, skipping: %v", id, err)

+		ps, found := p.poolAdd("pull", "layer:"+id)

+		if found {

+			logrus.Debugf("Image (id: %s) pull is already running, skipping", id)

 			msg := p.sf.FormatProgress(stringid.TruncateID(imgID), "Layer already being pulled by another client. Waiting.", nil)

 			ps.Wait(out, msg)

 		} else {

@@ -73,8 +73,8 @@ func (p *v2Puller) pullV2Repository(tag string) (err error) {

 	}

-	ps, err := p.poolAdd("pull", taggedName)

-	if err != nil {

+	ps, found := p.poolAdd("pull", taggedName)

+	if found {

 		// Another pull of the same repository is already taking place; just wait for it to finish

 		msg := p.sf.FormatStatus("", "Repository %s already being pulled by another client. Waiting.", p.repoInfo.CanonicalName)

 		ps.Wait(p.config.OutStream, msg)

@@ -119,8 +119,8 @@ func (p *v2Puller) download(di *downloadInfo) {

 	out := di.out

-	ps, err := p.poolAdd("pull", "img:"+di.img.ID)

-	if err != nil {

+	ps, found := p.poolAdd("pull", "img:"+di.img.ID)

+	if found {

 		msg := p.sf.FormatProgress(stringid.TruncateID(di.img.ID), "Layer already being pulled by another client. Waiting.", nil)

 		ps.Wait(out, msg)

 		out.Write(p.sf.FormatProgress(stringid.TruncateID(di.img.ID), "Download complete", nil))

@@ -214,7 +214,6 @@ func (p *v1Pusher) pushImageToEndpoint(endpoint string, imageIDs []string, tags

 // pushRepository pushes layers that do not already exist on the registry.

 func (p *v1Pusher) pushRepository(tag string) error {

-

 	logrus.Debugf("Local repo: %s", p.localRepo)

 	p.out = ioutils.NewWriteFlusher(p.config.OutStream)

 	imgList, tags, err := p.getImageList(tag)

@@ -229,8 +228,8 @@ func (p *v1Pusher) pushRepository(tag string) error {

 		logrus.Debugf("Pushing ID: %s with Tag: %s", data.ID, data.Tag)

 	}

-	if _, err := p.poolAdd("push", p.repoInfo.LocalName); err != nil {

-		return err

+	if _, found := p.poolAdd("push", p.repoInfo.LocalName); found {

+		return fmt.Errorf("push or pull %s is already in progress", p.repoInfo.LocalName)

 	}

 	defer p.poolRemove("push", p.repoInfo.LocalName)

@@ -57,8 +57,8 @@ func (p *v2Pusher) getImageTags(askedTag string) ([]string, error) {

 func (p *v2Pusher) pushV2Repository(tag string) error {

 	localName := p.repoInfo.LocalName

-	if _, err := p.poolAdd("push", localName); err != nil {

-		return err

+	if _, found := p.poolAdd("push", localName); found {

+		return fmt.Errorf("push or pull %s is already in progress", localName)

 	}

 	defer p.poolRemove("push", localName)

@@ -428,27 +428,32 @@ func validateDigest(dgst string) error {

 	return nil

 }

-func (store *TagStore) poolAdd(kind, key string) (*progressreader.ProgressStatus, error) {

+// poolAdd checks if a push or pull is already running, and returns (ps, true)

+// if a running operation is found. Otherwise, it creates a new one and returns

+// (ps, false).

+func (store *TagStore) poolAdd(kind, key string) (*progressreader.ProgressStatus, bool) {

 	store.Lock()

 	defer store.Unlock()

 	if p, exists := store.pullingPool[key]; exists {

-		return p, fmt.Errorf("pull %s is already in progress", key)

+		return p, true

 	}

 	if p, exists := store.pushingPool[key]; exists {

-		return p, fmt.Errorf("push %s is already in progress", key)

+		return p, true

 	}

 	ps := progressreader.NewProgressStatus()

+

 	switch kind {

 	case "pull":

 		store.pullingPool[key] = ps

 	case "push":

 		store.pushingPool[key] = ps

 	default:

-		return nil, fmt.Errorf("Unknown pool type")

+		panic("Unknown pool type")

 	}

-	return ps, nil

+

+	return ps, false

 }

 func (store *TagStore) poolRemove(kind, key string) error {