On Thu, Dec 9, 2021 at 6:16 PM Song Liu <song@xxxxxxxxxx> wrote:
>
> On Wed, Nov 10, 2021 at 10:15 AM Vishal Verma <vverma@xxxxxxxxxxxxxxxx> wrote:
> >
> > Returns EAGAIN in case the raid456 driver would block
> > waiting for situations like:
> >
> > - Reshape operation,
> > - Discard operation.
> >
> > Signed-off-by: Vishal Verma <vverma@xxxxxxxxxxxxxxxx>
> > ---
> > drivers/md/raid5.c | 14 ++++++++++++++
> > 1 file changed, 14 insertions(+)
> >
> > diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
> > index 9c1a5877cf9f..fa64ee315241 100644
> > --- a/drivers/md/raid5.c
> > +++ b/drivers/md/raid5.c
> > @@ -5710,6 +5710,11 @@ static void make_discard_request(struct mddev *mddev, struct bio *bi)
> > int d;
> > again:
> > sh = raid5_get_active_stripe(conf, logical_sector, 0, 0, 0);
> > + /* Bail out if REQ_NOWAIT is set */
> > + if (bi->bi_opf & REQ_NOWAIT) {
> > + bio_wouldblock_error(bi);
> > + return;
> > + }
>
> This is not right. raid5_get_active_stripe() gets refcount on the sh,
> we cannot simply
> return here. I think we need the logic after raid5_release_stripe()
> and before schedule().
>
> > prepare_to_wait(&conf->wait_for_overlap, &w,
> > TASK_UNINTERRUPTIBLE);
> > set_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
> > @@ -5820,6 +5825,15 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi)
> > bi->bi_next = NULL;
> >
> > md_account_bio(mddev, &bi);
> > + /* Bail out if REQ_NOWAIT is set */
> > + if (bi->bi_opf & REQ_NOWAIT &&
> > + conf->reshape_progress != MaxSector &&
> > + mddev->reshape_backwards
> > + ? logical_sector < conf->reshape_safe
> > + : logical_sector >= conf->reshape_safe) {
There is also an Operator Precedence bug here. "&&" goes before "?
:", so we need
"()" around the "? :" block.
Thanks,
Song
