[PATCH 3/5] io_uring/core: keep req->cqe.flags on generic errors

[Stefan Metzmacher <metze@samba.org>]

Soon we'll have the case where IORING_OP_SEND_ZC will
add IORING_CQE_F_MORE to req->cqe.flags before calling
into sock_sendmsg() and once we did that we have to
keep that flag even if we will hit some generic error
later, e.g. in the partial io retry case.

Hopefully passing req->cqe.flags to inline io_req_set_res(),
allows the compiler to optimize out the effective
req->cqe.flags = req->cqe.flags.

Fixes: b48c312be05e8 ("io_uring/net: simplify zerocopy send user API")
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: io-uring@vger.kernel.org
---
 io_uring/io_uring.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index ae69cff94664..062edbc04168 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -212,7 +212,7 @@ bool io_match_task_safe(struct io_kiocb *head, struct task_struct *task,
 static inline void req_fail_link_node(struct io_kiocb *req, int res)
 {
 	req_set_fail(req);
-	io_req_set_res(req, res, 0);
+	io_req_set_res(req, res, req->cqe.flags);
 }
 
 static inline void io_req_add_to_cache(struct io_kiocb *req, struct io_ring_ctx *ctx)
@@ -824,7 +824,8 @@ inline void __io_req_complete(struct io_kiocb *req, unsigned issue_flags)
 void io_req_complete_failed(struct io_kiocb *req, s32 res)
 {
 	req_set_fail(req);
-	io_req_set_res(req, res, io_put_kbuf(req, IO_URING_F_UNLOCKED));
+	req->cqe.flags |= io_put_kbuf(req, IO_URING_F_UNLOCKED);
+	io_req_set_res(req, res, req->cqe.flags);
 	io_req_complete_post(req);
 }
 
@@ -1106,7 +1107,7 @@ void io_req_task_submit(struct io_kiocb *req, bool *locked)
 
 void io_req_task_queue_fail(struct io_kiocb *req, int ret)
 {
-	io_req_set_res(req, ret, 0);
+	io_req_set_res(req, ret, req->cqe.flags);
 	req->io_task_work.func = io_req_task_cancel;
 	io_req_task_work_add(req);
 }
@@ -1847,6 +1848,7 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req,
 	/* same numerical values with corresponding REQ_F_*, safe to copy */
 	req->flags = sqe_flags = READ_ONCE(sqe->flags);
 	req->cqe.user_data = READ_ONCE(sqe->user_data);
+	req->cqe.flags = 0;
 	req->file = NULL;
 	req->rsrc_node = NULL;
 	req->task = current;
-- 
2.34.1