io_uring: optimise rw complete error handling

Expect read/write to succeed and create a hot path for this case, in
particular hide all error handling with resubmission under a single
check with the desired result.

Signed-off-by: Pavel Begunkov <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 a7239c86326e72e3d0afff239939d338de8989d1..c791e4031fb2eca6e6d135c43cb996afc6806dda 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2487,12 +2487,14 @@ static void __io_complete_rw(struct io_kiocb *req, long res, long res2,
 
        if (req->rw.kiocb.ki_flags & IOCB_WRITE)
                kiocb_end_write(req);
-       if ((res == -EAGAIN || res == -EOPNOTSUPP) && io_rw_should_reissue(req)) {
-               req->flags |= REQ_F_REISSUE;
-               return;
-       }
-       if (res != req->result)
+       if (res != req->result) {
+               if ((res == -EAGAIN || res == -EOPNOTSUPP) &&
+                   io_rw_should_reissue(req)) {
+                       req->flags |= REQ_F_REISSUE;
+                       return;
+               }
                req_set_fail_links(req);
+       }
        if (req->flags & REQ_F_BUFFER_SELECTED)
                cflags = io_put_rw_kbuf(req);
        __io_req_complete(req, issue_flags, res, cflags);
@@ -2509,19 +2511,20 @@ static void io_complete_rw_iopoll(struct kiocb *kiocb, long res, long res2)
 {
        struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw.kiocb);
 
-#ifdef CONFIG_BLOCK
-       if (res == -EAGAIN && io_rw_should_reissue(req)) {
-               if (!io_resubmit_prep(req))
-                       req->flags |= REQ_F_DONT_REISSUE;
-       }
-#endif
-
        if (kiocb->ki_flags & IOCB_WRITE)
                kiocb_end_write(req);
+       if (unlikely(res != req->result)) {
+               bool fail = true;
 
-       if (res != -EAGAIN && res != req->result) {
-               req->flags |= REQ_F_DONT_REISSUE;
-               req_set_fail_links(req);
+#ifdef CONFIG_BLOCK
+               if (res == -EAGAIN && io_rw_should_reissue(req) &&
+                   io_resubmit_prep(req))
+                       fail = false;
+#endif
+               if (fail) {
+                       req_set_fail_links(req);
+                       req->flags |= REQ_F_DONT_REISSUE;
+               }
        }
 
        WRITE_ONCE(req->result, res);