Re: [PATCH] block/file-posix: fix update_zones_wp() caller

[Sam Li <faithilikerun@gmail.com>]

Damien Le Moal <dlemoal@kernel.org> 于2023年8月25日周五 07:49写道：
>
> On 8/25/23 02:39, Sam Li wrote:
> > When the zoned requests that may change wp fail, it needs to
> > update only wps of the zones within the range of the requests
> > for not disrupting the other in-flight requests. The wp is updated
> > successfully after the request completes.
> >
> > Fixed the callers with right offset and nr_zones.
> >
> > Signed-off-by: Sam Li <faithilikerun@gmail.com>
> > ---
> >  block/file-posix.c | 5 +++--
> >  1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/block/file-posix.c b/block/file-posix.c
> > index b16e9c21a1..22559d6c2d 100644
> > --- a/block/file-posix.c
> > +++ b/block/file-posix.c
> > @@ -2522,7 +2522,8 @@ out:
> >          }
> >      } else {
> >          if (type & (QEMU_AIO_WRITE | QEMU_AIO_ZONE_APPEND)) {
> > -            update_zones_wp(bs, s->fd, 0, 1);
> > +            update_zones_wp(bs, s->fd, offset,
> > +                            ROUND_UP(bytes, bs->bl.zone_size));
>
> Write and zone append operations are not allowed to cross zone boundaries. So I
> the number of zones should always be 1. The above changes a number of zones to a
> number of bytes, which seems wrong. The correct fix is I think:
>
>                 update_zones_wp(bs, s->fd, offset, 1);
>

I see. I forgot this constraint.

> >          }
> >      }
> >
> > @@ -3472,7 +3473,7 @@ static int coroutine_fn raw_co_zone_mgmt(BlockDriverState *bs, BlockZoneOp op,
> >                          len >> BDRV_SECTOR_BITS);
> >      ret = raw_thread_pool_submit(handle_aiocb_zone_mgmt, &acb);
> >      if (ret != 0) {
> > -        update_zones_wp(bs, s->fd, offset, i);
> > +        update_zones_wp(bs, s->fd, offset, nrz);
>
> Same here. Why would you need to update all zones wp ? This will affect zones
> that do not have a write error and potentially change there correct in-memory wp
> to a wrong value. I think this also should be:
>
>            update_zones_wp(bs, s->fd, offset, 1);
>

Is update_zones_wp for cancelling the writes on invalid zones or
updating corrupted write pointers caused by caller (write, append or
zone_mgmt)?

My thought is based on the latter. Zone_mgmt can manage multiple zones
with a single request. When the request fails, it's hard to tell which
zone is corrupted. The relation between the req (zone_mgmt) and
update_zones_wp is: if req succeeds, no updates; if req fails,
consider the req never happens and do again.

If the former is right, then it assumes only the first zone may
contain an error. I am not sure it's right.

> >          error_report("ioctl %s failed %d", op_name, ret);
> >          return ret;
> >      }
>
> --
> Damien Le Moal
> Western Digital Research
>