On 2/25/20 2:22 PM, Pavel Begunkov wrote: > On 25/02/2020 23:27, Jens Axboe wrote: >> If work completes inline, then we should pick up a dependent link item >> in __io_queue_sqe() as well. If we don't do so, we're forced to go async >> with that item, which is suboptimal. >> >> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> >> >> --- >> >> diff --git a/fs/io_uring.c b/fs/io_uring.c >> index ffd9bfa84d86..160cf1b0f478 100644 >> --- a/fs/io_uring.c >> +++ b/fs/io_uring.c >> @@ -4531,8 +4531,15 @@ static void io_wq_submit_work(struct io_wq_work **workptr) >> } while (1); >> } >> >> - /* drop submission reference */ >> - io_put_req(req); >> + /* >> + * Drop submission reference. In case the handler already dropped the >> + * completion reference, then it didn't pick up any potential link >> + * work. If 'nxt' isn't set, try and do that here. >> + */ >> + if (nxt) > > It can't even get here, because of the submission ref, isn't it? would the > following do? > > - io_put_req(req); > + io_put_req_find_next(req, &nxt); I don't think it can, let me make that change. And test. > BTW, as I mentioned before, it appears to me, we don't even need completion ref > as it always pinned by the submission ref. I'll resurrect the patches doing > that, but after your poll work will land. We absolutely do need two references, unfortunately. Otherwise we could complete the io_kiocb deep down the stack through the callback. -- Jens Axboe
