io_uring: fix an issue when IOSQE_IO_LINK is inserted into defer list
This patch may fix two issues:
First, when IOSQE_IO_DRAIN set, the next IOs need to be inserted into
defer list to delay execution, but link io will be actively scheduled to
run by calling io_queue_sqe.
Second, when multiple LINK_IOs are inserted together with defer_list,
the LINK_IO is no longer keep order.
|-------------|
| LINK_IO | ----> insert to defer_list -----------
|-------------| |
| LINK_IO | ----> insert to defer_list ----------|
|-------------| |
| LINK_IO | ----> insert to defer_list ----------|
|-------------| |
| NORMAL_IO | ----> insert to defer_list ----------|
|-------------| |
|
queue_work at same time <-----|
Fixes: 9e645e1105c ("io_uring: add support for sqe links")
Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/fs/io_uring.c b/fs/io_uring.c
index aa25b5b..24bbe3c 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2023,6 +2023,15 @@ static int io_queue_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
{
int ret;
+ ret = io_req_defer(ctx, req, s->sqe);
+ if (ret) {
+ if (ret != -EIOCBQUEUED) {
+ io_free_req(req);
+ io_cqring_add_event(ctx, s->sqe->user_data, ret);
+ }
+ return 0;
+ }
+
ret = __io_submit_sqe(ctx, req, s, true);
if (ret == -EAGAIN && !(req->flags & REQ_F_NOWAIT)) {
struct io_uring_sqe *sqe_copy;
@@ -2095,13 +2104,6 @@ static void io_submit_sqe(struct io_ring_ctx *ctx, struct sqe_submit *s,
return;
}
- ret = io_req_defer(ctx, req, s->sqe);
- if (ret) {
- if (ret != -EIOCBQUEUED)
- goto err_req;
- return;
- }
-
/*
* If we already have a head request, queue this one for async
* submittal once the head completes. If we don't have a head but
