On Tue, Sep 20, 2022 at 11:24:12AM +0800, Ziyang Zhang wrote:
> On 2022/9/20 11:04, Ming Lei wrote:
> > On Tue, Sep 20, 2022 at 09:49:33AM +0800, Ziyang Zhang wrote:
> >
> > Follows the delta patch against patch 5 for showing the idea:
> >
> >
> > diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
> > index 4409a130d0b6..60c5786c4711 100644
> > --- a/drivers/block/ublk_drv.c
> > +++ b/drivers/block/ublk_drv.c
> > @@ -656,7 +656,8 @@ static void ublk_complete_rq(struct request *req)
> > * Also aborting may not be started yet, keep in mind that one failed
> > * request may be issued by block layer again.
> > */
> > -static void __ublk_fail_req(struct ublk_io *io, struct request *req)
> > +static void __ublk_fail_req(struct ublk_queue *ubq, struct ublk_io *io,
> > + struct request *req)
> > {
> > WARN_ON_ONCE(io->flags & UBLK_IO_FLAG_ACTIVE);
> >
> > @@ -667,7 +668,10 @@ static void __ublk_fail_req(struct ublk_io *io, struct request *req)
> > req->tag,
> > io->flags);
> > io->flags |= UBLK_IO_FLAG_ABORTED;
> > - blk_mq_end_request(req, BLK_STS_IOERR);
> > + if (ublk_queue_can_use_recovery_reissue(ubq))
> > + blk_mq_requeue_request(req, false);
>
> Here is one problem:
> We reset io->flags to 0 in ublk_queue_reinit() and it is called before new
As we agreed, ublk_queue_reinit() will be moved to ublk_ch_release(), when there isn't
any inflight request, which is completed by either ublk server or __ublk_fail_req().
So clearing io->flags isn't related with quisceing device.
> ubq_daemon with FETCH_REQ is accepted. ublk_abort_queue() is not protected with
> ub_mutex and it is called many times in monitor_work. So same rq may be requeued
> multiple times.
UBLK_IO_FLAG_ABORTED is set for the slot, so one req is only ended or
requeued just once.
>
> With recovery disabled, there is no such problem since io->flags does not change
> until ublk_dev is released.
But we have agreed that ublk_queue_reinit() can be moved to release
handler of /dev/ublkcN.
>
> In my patch 5 I only requeue the same rq once. So re-using ublk_abort_queue() is
> hard for recovery feature.
No, the same rq is just requeued once. Here the point is:
1) reuse previous pattern in ublk_stop_dev(), which is proved as
workable reliably
2) avoid to stay in half-working state forever
3) the behind idea is more simpler.
Thanks.
Ming
