fix: cleanup locking, cancel context upon lock timeout (#12183)

upon errors to acquire lock context would still leak,
since the cancel would never be called. since the lock
is never acquired - proactively clear it before returning.

cmd/erasure-healing.go

@@ -253,12 +253,13 @@ func (er erasureObjects) healObject(ctx context.Context, bucket string, object s
 	}
 
 	if !opts.NoLock {
-		var cancel context.CancelFunc
 		lk := er.NewNSLock(bucket, object)
-		if ctx, cancel, err = lk.GetLock(ctx, globalOperationTimeout); err != nil {
+		lkctx, err := lk.GetLock(ctx, globalOperationTimeout)
+		if err != nil {
 			return result, err
 		}
-		defer lk.Unlock(cancel)
+		ctx = lkctx.Context()
+		defer lk.Unlock(lkctx.Cancel)
 	}
 
 	// Re-read when we have lock...