Reserved tags are used for error handling, we don't need to
care about them for regular IO. The core won't call us for these
anyway.
Acked-by: NPaolo Valente <paolo.valente@linaro.org>
Reviewed-by: NOmar Sandoval <osandov@fb.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>