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Commit a982eeb0 authored by Jackie Liu's avatar Jackie Liu Committed by Jens Axboe
Browse files

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: 9e645e11 ("io_uring: add support for sqe links")
Signed-off-by: default avatarJackie Liu <liuyun01@kylinos.cn>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 7b6620d7

fs/io_uring.c

+9 −7
Original line number Diff line number Diff line
@@ -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