Re: [PATCH v2 1/4] md/raid10: cleanup wait_barrier()

[Yu Kuai]

Hi, Paul

在 2022/09/14 14:36, Paul Menzel 写道:
> Dear Yu,
>
>
> Thank you for the improved patch. Three minor nits.
>
> Am 14.09.22 um 03:49 schrieb Yu Kuai:
> > From: Yu Kuai <yukuai3@xxxxxxxxxx>
>
> In the summary/title, I’d spell *Clean up* with a space. Maybe even use:
>
> md/raid10: Factor out code from wait_barrier() to stop_waiting_barrier()

Ok, sounds good, I'll change that in next version.
> > Currently the nasty condition is wait_barrier() is hard to read. This
> > patch factor out the condition into a function.
>
> The first *is* above can be removed, and factor*s* needs an s.

Yes, you're right.
> > There are no functional changes.
> >
> > Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
> > ---
> >   drivers/md/raid10.c | 56 ++++++++++++++++++++++++++-------------------
> >   1 file changed, 32 insertions(+), 24 deletions(-)
> >
> > diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
> > index 64d6e4cd8a3a..56458a53043d 100644
> > --- a/drivers/md/raid10.c
> > +++ b/drivers/md/raid10.c
> > @@ -957,44 +957,52 @@ static void lower_barrier(struct r10conf *conf)
> >       wake_up(&conf->wait_barrier);
> >   }
> > +static bool stop_waiting_barrier(struct r10conf *conf)
> > +{
> > +    /* barrier is dropped */
> > +    if (!conf->barrier)
> > +        return true;
> > +
> > +    /*
> > +     * If there are already pending requests (preventing the barrier 
> > from
> > +     * rising completely), and the pre-process bio queue isn't empty, 
> > then
> > +     * don't wait, as we need to empty that queue to get the nr_pending
> > +     * count down.
> > +     */
> > +    if (atomic_read(&conf->nr_pending)) {
> > +        struct bio_list *bio_list = current->bio_list;
> > +
> > +        if (bio_list && (!bio_list_empty(&bio_list[0]) ||
> > +                 !bio_list_empty(&bio_list[1])))
> > +            return true;
> > +    }
> > +
> > +    /* move on if recovery thread is blocked by us */
> > +    if (conf->mddev->thread->tsk == current &&
> > +        test_bit(MD_RECOVERY_RUNNING, &conf->mddev->recovery) &&
> > +        conf->nr_queued > 0)
> > +        return true;
> > +
> > +    return false;
> > +}
> > +
> >   static bool wait_barrier(struct r10conf *conf, bool nowait)
> >   {
> >       bool ret = true;
> >       spin_lock_irq(&conf->resync_lock);
> >       if (conf->barrier) {
> > -        struct bio_list *bio_list = current->bio_list;
> > -        conf->nr_waiting++;
> > -        /* Wait for the barrier to drop.
> > -         * However if there are already pending
> > -         * requests (preventing the barrier from
> > -         * rising completely), and the
> > -         * pre-process bio queue isn't empty,
> > -         * then don't wait, as we need to empty
> > -         * that queue to get the nr_pending
> > -         * count down.
> > -         */
> >           /* Return false when nowait flag is set */
> >           if (nowait) {
> >               ret = false;
> >           } else {
> > +            conf->nr_waiting++;
> >               raid10_log(conf->mddev, "wait barrier");
> >               wait_event_lock_irq(conf->wait_barrier,
> > -                        !conf->barrier ||
> > -                        (atomic_read(&conf->nr_pending) &&
> > -                         bio_list &&
> > -                         (!bio_list_empty(&bio_list[0]) ||
> > -                          !bio_list_empty(&bio_list[1]))) ||
> > -                         /* move on if recovery thread is
> > -                          * blocked by us
> > -                          */
> > -                         (conf->mddev->thread->tsk == current &&
> > -                          test_bit(MD_RECOVERY_RUNNING,
> > -                               &conf->mddev->recovery) &&
> > -                          conf->nr_queued > 0),
> > +                        stop_waiting_barrier(conf),
> >                           conf->resync_lock);
> > +            conf->nr_waiting--;
> >           }
> > -        conf->nr_waiting--;
> >           if (!conf->nr_waiting)
> >               wake_up(&conf->wait_barrier);
> >       }
>
> Acked-by: Paul Menzel <pmenzel@xxxxxxxxxxxxx>

Thanks,
Kuai
> Kind regards,
>
> Paul
>
> .