io_uring: optimise rw comletion handlers

Don't override req->result in io_complete_rw_iopoll() when it's already
of the same value, we have an if just above it, so move the assignment
there. Also, add one simle unlikely() in __io_complete_rw_common().

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/8dfeb4f84026a20172bcf82c05010abe955874ae.1634144845.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 86ef803..18a91d2 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2640,7 +2640,7 @@ static bool __io_complete_rw_common(struct io_kiocb *req, long res)
 {
        if (req->rw.kiocb.ki_flags & IOCB_WRITE)
                kiocb_end_write(req);
-       if (res != req->result) {
+       if (unlikely(res != req->result)) {
                if ((res == -EAGAIN || res == -EOPNOTSUPP) &&
                    io_rw_should_reissue(req)) {
                        req->flags |= REQ_F_REISSUE;
@@ -2695,9 +2695,9 @@ static void io_complete_rw_iopoll(struct kiocb *kiocb, long res, long res2)
                        req->flags |= REQ_F_REISSUE;
                        return;
                }
+               req->result = res;
        }
 
-       req->result = res;
        /* order with io_iopoll_complete() checking ->iopoll_completed */
        smp_store_release(&req->iopoll_completed, 1);
 }