io_uring: clear F_REISSUE right after getting it

There are lots of ways r/w request may continue its path after getting
REQ_F_REISSUE, it's not necessarily io-wq and can be, e.g. apoll,
and submitted via  io_async_task_func() -> __io_req_task_submit()

Clear the flag right after getting it, so the next attempt is well
prepared regardless how the request will be executed.

Fixes: 230d50d ("io_uring: move reissue into regular IO path")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/11dcead939343f4e27cab0074d34afcab771bfa4.1617842918.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -3294,6 +3294,7 @@ static int io_read(struct io_kiocb *req, unsigned int issue_flags)
 	ret = io_iter_do_read(req, iter);
 
 	if (ret == -EAGAIN || (req->flags & REQ_F_REISSUE)) {
+		req->flags &= ~REQ_F_REISSUE;
 		/* IOPOLL retry should happen for io-wq threads */
 		if (!force_nonblock && !(req->ctx->flags & IORING_SETUP_IOPOLL))
 			goto done;
@@ -3417,8 +3418,10 @@ static int io_write(struct io_kiocb *req, unsigned int issue_flags)
 	else
 		ret2 = -EINVAL;
 
-	if (req->flags & REQ_F_REISSUE)
+	if (req->flags & REQ_F_REISSUE) {
+		req->flags &= ~REQ_F_REISSUE;
 		ret2 = -EAGAIN;
+	}
 
 	/*
 	 * Raw bdev writes will return -EOPNOTSUPP for IOCB_NOWAIT. Just
@@ -6173,7 +6176,6 @@ static void io_wq_submit_work(struct io_wq_work *work)
 		ret = -ECANCELED;
 
 	if (!ret) {
-		req->flags &= ~REQ_F_REISSUE;
 		do {
 			ret = io_issue_sqe(req, 0);
 			/*