io_uring: reshuffle queue_sqe completion handling

io_uring: reshuffle queue_sqe completion handling

If a request completed inline the result should only be zero, it's a
grave error otherwise. So, when we see REQ_F_COMPLETE_INLINE it's not
even necessary to check the return code, and the flag check can be moved
earlier.

It's one "if" less for inline completions, and same two checks for it
normally completing (ret == 0). Those are two cases we care about the
most.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/ebd4e397a9c26d96c99b24447acc309741041a83.1632516769.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>