io_uring/nop: pass all errors to userspace

[ Upstream commit e97ff8b62d4690c69297f0f6de874f0564cc01a4 ]

This fixes an inconsistency where io_nop() called req_set_fail()
based on ret, but passed just nop->result to userspace.
Originally, ret is a even copy of nop->result, but is set to an error
when such happens subsequently. Now that's also passed to userspace.

Fixes: a85f310 ("io_uring/nop: add support for testing registered files and buffers")
Signed-off-by: Alexander A. Klimov <grandmaster@al2klimov.de>
Link: https://patch.msgid.link/20260520180045.538533-1-grandmaster@al2klimov.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
(cherry picked from commit 6836f694126e5dfb44da4f77706ae29e45cc2e1e)
Signed-off-by: Wentao Guan <guanwentao@uniontech.com>

Author: Al2Klimov

io_uring/nop.c

@@ -79,9 +79,9 @@ int io_nop(struct io_kiocb *req, unsigned int issue_flags)
 	if (ret < 0)
 		req_set_fail(req);
 	if (nop->flags & IORING_NOP_CQE32)
-		io_req_set_res32(req, nop->result, 0, nop->extra1, nop->extra2);
+		io_req_set_res32(req, ret, 0, nop->extra1, nop->extra2);
 	else
-		io_req_set_res(req, nop->result, 0);
+		io_req_set_res(req, ret, 0);
 	if (nop->flags & IORING_NOP_TW) {
 		req->io_task_work.func = io_req_task_complete;
 		io_req_task_work_add(req);