if opts.CheckPrecondFn != nil {
		// Lock the object before reading.
		lk := er.NewNSLock(bucket, object)
		lkctx, err := lk.GetRLock(ctx, globalOperationTimeout)
		if err != nil {
			return nil, err
		}
		rctx := lkctx.Context()
		obj, err := er.getObjectInfo(rctx, bucket, object, opts)
		lk.RUnlock(lkctx)

	nsUnlocker := func() {}
	defer func() {
		if unlockOnDefer {
			nsUnlocker()
		}
	}()

	// Acquire lock
	if !opts.NoLock {
		lock := er.NewNSLock(bucket, object)
		lkctx, err := lock.GetRLock(ctx, globalOperationTimeout)
		if err != nil {
			return nil, err
		}
		ctx = lkctx.Context()

		// Release lock when the metadata is verified, and reader
		// is ready to be read.
		//

	nsUnlocker := func() {}
	defer func() {
		if unlockOnDefer {
			nsUnlocker()
		}
	}()

	// Acquire lock
	if !opts.NoLock {
		lock := z.NewNSLock(bucket, object)
		lkctx, err := lock.GetRLock(ctx, globalOperationTimeout)
		if err != nil {
			return nil, err
		}
		ctx = lkctx.Context()
		nsUnlocker = func() { lock.RUnlock(lkctx) }
		unlockOnDefer = true
	}

		return
	}

	// Take read lock on object, here so subsequent lower-level
	// calls do not need to.
	lock := objectAPI.NewNSLock(bucket, object)
	lkctx, err := lock.GetRLock(ctx, globalOperationTimeout)
	if err != nil {
		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
		return
	}
	ctx = lkctx.Context()
	defer lock.RUnlock(lkctx)