Re: [PATCH 08/13] lightnvm: pblk: Set proper read stutus in bio

From: Hans Holmberg <hans.ml.holmberg@owltronix.com>
To: "Javier González" <javier@javigon.com>
Cc: "Konopko, Igor J" <igor.j.konopko@intel.com>,
	"Matias Bjørling" <mb@lightnvm.io>,
	"Hans Holmberg" <hans.holmberg@cnexlabs.com>,
	linux-block@vger.kernel.org
Subject: Re: [PATCH 08/13] lightnvm: pblk: Set proper read stutus in bio
Date: Mon, 4 Mar 2019 10:35:07 +0100	[thread overview]
Message-ID: <CANr-nt1o4ZyRW-MwwXHQ7aXTmOr8PsqRzhR3643iddh9H2kjjg@mail.gmail.com> (raw)
In-Reply-To: <007EC669-9C50-4B29-9522-CE73CD3CE47F@javigon.com>

On Mon, Mar 4, 2019 at 9:03 AM Javier González <javier@javigon.com> wrote:
>
> > On 27 Feb 2019, at 18.14, Igor Konopko <igor.j.konopko@intel.com> wrote:
> >
> > Currently in case of read errors, bi_status is not
> > set properly which leads to returning inproper data
> > to higher layer. This patch fix that by setting proper
> > status in case of read errors
> >
> > Patch also removes unnecessary warn_once(), which does
> > not make sense in that place, since user bio is not used
> > for interation with drive and thus bi_status will not be
> > set here.
> >
> > Signed-off-by: Igor Konopko <igor.j.konopko@intel.com>
> > ---
> > drivers/lightnvm/pblk-read.c | 11 +++++------
> > 1 file changed, 5 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/lightnvm/pblk-read.c b/drivers/lightnvm/pblk-read.c
> > index 3789185144da..39c1d6ccaedb 100644
> > --- a/drivers/lightnvm/pblk-read.c
> > +++ b/drivers/lightnvm/pblk-read.c
> > @@ -175,11 +175,10 @@ static void pblk_read_check_rand(struct pblk *pblk, struct nvm_rq *rqd,
> >       WARN_ONCE(j != rqd->nr_ppas, "pblk: corrupted random request\n");
> > }
> >
> > -static void pblk_end_user_read(struct bio *bio)
> > +static void pblk_end_user_read(struct bio *bio, int error)
> > {
> > -#ifdef CONFIG_NVM_PBLK_DEBUG
> > -     WARN_ONCE(bio->bi_status, "pblk: corrupted read bio\n");
> > -#endif
> > +     if (error && error != NVM_RSP_WARN_HIGHECC)
> > +             bio_io_error(bio);
> >       bio_endio(bio);
> > }
> >
> > @@ -219,7 +218,7 @@ static void pblk_end_io_read(struct nvm_rq *rqd)
> >       struct pblk_g_ctx *r_ctx = nvm_rq_to_pdu(rqd);
> >       struct bio *bio = (struct bio *)r_ctx->private;
> >
> > -     pblk_end_user_read(bio);
> > +     pblk_end_user_read(bio, rqd->error);
> >       __pblk_end_io_read(pblk, rqd, true);
> > }
> >
> > @@ -292,7 +291,7 @@ static void pblk_end_partial_read(struct nvm_rq *rqd)
> >       rqd->bio = NULL;
> >       rqd->nr_ppas = nr_secs;
> >
> > -     bio_endio(bio);
> > +     pblk_end_user_read(bio, rqd->error);
> >       __pblk_end_io_read(pblk, rqd, false);
> > }
> >
> > --
> > 2.17.1
>
> This is by design. We do not report the read errors as in any other
> block device - this is why we clone the read bio.

Could you elaborate on why not reporting read errors is a good thing in pblk?

>
> If you want to remove the WARN_ONCE, it is fine by me - it helped in the
> past to debug the read path as when one read failed we go a storm of
> them. Now we have better controller tools to debug this, so if nobody
> else wants it there, let’s remove it.
>
> Javier