From a982eeb09b6030e567b8b815277c8c9197168040 Mon Sep 17 00:00:00 2001 From: Jackie Liu Date: Wed, 14 Aug 2019 17:35:22 +0800 Subject: [PATCH] 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 Signed-off-by: Jens Axboe --- fs/io_uring.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) 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 @@ err: 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 -- 2.7.4