fix(fs): deadlock when get link error (#963)

internal/op/fs.go

@@ -295,7 +295,6 @@ func Link(ctx context.Context, storage driver.Driver, path string, args model.Li
 	fn := func() (*model.Link, error) {
 		link, err := storage.Link(ctx, file, args)
 		if err != nil {
-			linkG.Forget(key)
 			return nil, errors.Wrapf(err, "failed get link")
 		}
 		if link.Expiration != nil {

pkg/singleflight/singleflight.go

@@ -74,6 +74,7 @@ type Group[T any] struct {
 	mu sync.Mutex          // protects m
 	m  map[string]*call[T] // lazily initialized
 
+	// Won't remember error
 	Remember bool
 }
 
@@ -158,7 +159,7 @@ func (g *Group[T]) doCall(c *call[T], key string, fn func() (T, error)) {
 		g.mu.Lock()
 		defer g.mu.Unlock()
 		c.wg.Done()
-		if !g.Remember && g.m[key] == c {
+		if (!g.Remember || c.err != nil) && g.m[key] == c {
 			delete(g.m, key)
 		}