On Wed, Feb 16, 2022 at 12:39 AM Pankaj Gupta
<pankaj.gupta.linux@xxxxxxxxx> wrote:
>
> > >
> > > Return from "pmem_submit_bio" when asynchronous flush is
> > > still in progress in other context.
> > >
> > > Signed-off-by: Pankaj Gupta <pankaj.gupta.linux@xxxxxxxxx>
> > > ---
> > > drivers/nvdimm/pmem.c | 15 ++++++++++++---
> > > drivers/nvdimm/region_devs.c | 4 +++-
> > > 2 files changed, 15 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
> > > index fe7ece1534e1..f20e30277a68 100644
> > > --- a/drivers/nvdimm/pmem.c
> > > +++ b/drivers/nvdimm/pmem.c
> > > @@ -201,8 +201,12 @@ static void pmem_submit_bio(struct bio *bio)
> > > struct pmem_device *pmem = bio->bi_bdev->bd_disk->private_data;
> > > struct nd_region *nd_region = to_region(pmem);
> > >
> > > - if (bio->bi_opf & REQ_PREFLUSH)
> > > + if (bio->bi_opf & REQ_PREFLUSH) {
> > > ret = nvdimm_flush(nd_region, bio);
> > > + /* asynchronous flush completes in other context */
> >
> > I think a negative error code is a confusing way to capture the case
> > of "bio successfully coalesced to previously pending flush request.
> > Perhaps reserve negative codes for failure, 0 for synchronously
> > completed, and > 0 for coalesced flush request.
>
> Yes. I implemented this way previously, will revert it to. Thanks!
>
> >
> > > + if (ret == -EINPROGRESS)
> > > + return;
> > > + }
> > >
> > > do_acct = blk_queue_io_stat(bio->bi_bdev->bd_disk->queue);
> > > if (do_acct)
> > > @@ -222,13 +226,18 @@ static void pmem_submit_bio(struct bio *bio)
> > > if (do_acct)
> > > bio_end_io_acct(bio, start);
> > >
> > > - if (bio->bi_opf & REQ_FUA)
> > > + if (bio->bi_opf & REQ_FUA) {
> > > ret = nvdimm_flush(nd_region, bio);
> > > + /* asynchronous flush completes in other context */
> > > + if (ret == -EINPROGRESS)
> > > + return;
> > > + }
> > >
> > > if (ret)
> > > bio->bi_status = errno_to_blk_status(ret);
> > >
> > > - bio_endio(bio);
> > > + if (bio)
> > > + bio_endio(bio);
> > > }
> > >
> > > static int pmem_rw_page(struct block_device *bdev, sector_t sector,
> > > diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
> > > index 9ccf3d608799..8512d2eaed4e 100644
> > > --- a/drivers/nvdimm/region_devs.c
> > > +++ b/drivers/nvdimm/region_devs.c
> > > @@ -1190,7 +1190,9 @@ int nvdimm_flush(struct nd_region *nd_region, struct bio *bio)
> > > if (!nd_region->flush)
> > > rc = generic_nvdimm_flush(nd_region);
> > > else {
> > > - if (nd_region->flush(nd_region, bio))
> > > + rc = nd_region->flush(nd_region, bio);
> > > + /* ongoing flush in other context */
> > > + if (rc && rc != -EINPROGRESS)
> > > rc = -EIO;
> >
> > Why change this to -EIO vs just let the error code through untranslated?
>
> The reason was to be generic error code instead of returning host side
> return codes to guest?
Ok, maybe a comment to indicate the need to avoid exposing these error
codes toa guest so someone does not ask the same question in the
future?
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