On 08/04/2021 19:28, Pavel Begunkov wrote:
> WARNING: at fs/io_uring.c:8578 io_ring_exit_work.cold+0x0/0x18
>
> As reissuing is now passed back by REQ_F_REISSUE and kiocb_done()
> internally uses __io_complete_rw(), it may stop after setting the flag
> so leaving a dangling request.
Jens, this one is instead of taken v1, it handles io_rw_reissue() errors.
The handling code is partially hand coded __io_complete_rw(). Obviously,
needs cleaning in the nearest future.
>
> There are tricky edge cases, e.g. reading beyound file, boundary, so
> the easiest way is to hand code reissue in kiocb_done() as
> __io_complete_rw() was doing for us before.
>
> Fixes: 230d50d448ac ("io_uring: move reissue into regular IO path")
> Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
> Link: https://lore.kernel.org/r/f602250d292f8a84cca9a01d747744d1e797be26.1617842918.git.asml.silence@xxxxxxxxx
> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
> ---
>
>
> v2: io_rw_reissue() may fail, check return code
> v3: adjust commit message
>
> fs/io_uring.c | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index f1881ac0744b..f2df0569a60a 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -2762,6 +2762,7 @@ static void kiocb_done(struct kiocb *kiocb, ssize_t ret,
> {
> struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw.kiocb);
> struct io_async_rw *io = req->async_data;
> + bool check_reissue = (kiocb->ki_complete == io_complete_rw);
>
> /* add previously done IO, if any */
> if (io && io->bytes_done > 0) {
> @@ -2777,6 +2778,18 @@ static void kiocb_done(struct kiocb *kiocb, ssize_t ret,
> __io_complete_rw(req, ret, 0, issue_flags);
> else
> io_rw_done(kiocb, ret);
> +
> + if (check_reissue && req->flags & REQ_F_REISSUE) {
> + req->flags &= ~REQ_F_REISSUE;
> + if (!io_rw_reissue(req)) {
> + int cflags = 0;
> +
> + req_set_fail_links(req);
> + if (req->flags & REQ_F_BUFFER_SELECTED)
> + cflags = io_put_rw_kbuf(req);
> + __io_req_complete(req, issue_flags, ret, cflags);
> + }
> + }
> }
>
> static int io_import_fixed(struct io_kiocb *req, int rw, struct iov_iter *iter)
>
--
Pavel Begunkov
