io_uring: hide iter revert in resubmit_prep

Move iov_iter_revert() resetting iterator in case of -EIOCBQUEUED into
io_resubmit_prep(), so we don't do heavy revert in hot path, also saves
a couple of checks.

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 9362c92285401a07ba5ebb73e0d5f0746ffcd0af..a7239c86326e72e3d0afff239939d338de8989d1 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2445,8 +2445,13 @@ static void kiocb_end_write(struct io_kiocb *req)
 #ifdef CONFIG_BLOCK
 static bool io_resubmit_prep(struct io_kiocb *req)
 {
-       /* either already prepared or successfully done */
-       return req->async_data || !io_req_prep_async(req);
+       struct io_async_rw *rw = req->async_data;
+
+       if (!rw)
+               return !io_req_prep_async(req);
+       /* may have left rw->iter inconsistent on -EIOCBQUEUED */
+       iov_iter_revert(&rw->iter, req->result - iov_iter_count(&rw->iter));
+       return true;
 }
 
 static bool io_rw_should_reissue(struct io_kiocb *req)
@@ -2505,14 +2510,8 @@ 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
-       /* Rewind iter, if we have one. iopoll path resubmits as usual */
        if (res == -EAGAIN && io_rw_should_reissue(req)) {
-               struct io_async_rw *rw = req->async_data;
-
-               if (rw)
-                       iov_iter_revert(&rw->iter,
-                                       req->result - iov_iter_count(&rw->iter));
-               else if (!io_resubmit_prep(req))
+               if (!io_resubmit_prep(req))
                        req->flags |= REQ_F_DONT_REISSUE;
        }
 #endif