Re: [PATCH v3 3/8] parallels: Use generic infrastructure for BAT writing in parallels_co_check()

[Denis V. Lunev]

On 17.08.2022 21:48, Vladimir Sementsov-Ogievskiy wrote:
> On 8/15/22 12:02, Alexander Ivanov wrote:
> > BAT is written in the context of conventional operations over
> > the image inside bdrv_co_flush() when it calls
> > parallels_co_flush_to_os() callback. Thus we should not
> > modify BAT array directly, but call parallels_set_bat_entry()
> > helper and bdrv_co_flush() further on. After that there is no
> > need to manually write BAT and track its modification.
> >
> > This makes code more generic and allows to split
> > parallels_set_bat_entry() for independent pieces.
> >
> > Signed-off-by: Alexander Ivanov <alexander.ivanov@virtuozzo.com>
> > ---
> > v2: Patch order was changed so the replacement is done in 
> > parallels_co_check.
> >      Now we use a helper to set BAT entry and mark the block dirty.
> > v3: Fix commit message.
> >
> >   block/parallels.c | 19 +++++++------------
> >   1 file changed, 7 insertions(+), 12 deletions(-)
> >
> > diff --git a/block/parallels.c b/block/parallels.c
> > index 7f68f3cbc9..6879ea4597 100644
> > --- a/block/parallels.c
> > +++ b/block/parallels.c
> > @@ -428,7 +428,6 @@ static int coroutine_fn 
> > parallels_co_check(BlockDriverState *bs,
> >       int64_t size, prev_off, high_off;
> >       int ret;
> >       uint32_t i;
> > -    bool flush_bat = false;
> >         size = bdrv_getlength(bs->file->bs);
> >       if (size < 0) {
> > @@ -467,9 +466,8 @@ static int coroutine_fn 
> > parallels_co_check(BlockDriverState *bs,
> >               res->corruptions++;
> >               if (fix & BDRV_FIX_ERRORS) {
> >                   prev_off = 0;
> > -                s->bat_bitmap[i] = 0;
> > +                parallels_set_bat_entry(s, i, 0);
> >                   res->corruptions_fixed++;
> > -                flush_bat = true;
> >                   continue;
> >               }
> >           }
> > @@ -485,15 +483,6 @@ static int coroutine_fn 
> > parallels_co_check(BlockDriverState *bs,
> >           prev_off = off;
> >       }
> >   -    ret = 0;
> > -    if (flush_bat) {
> > -        ret = bdrv_co_pwrite_sync(bs->file, 0, s->header_size, 
> > s->header, 0);
> > -        if (ret < 0) {
> > -            res->check_errors++;
> > -            goto out;
> > -        }
> > -    }
> > -
> >       res->image_end_offset = high_off + s->cluster_size;
> >       if (size > res->image_end_offset) {
> >           int64_t count;
> > @@ -522,6 +511,12 @@ static int coroutine_fn 
> > parallels_co_check(BlockDriverState *bs,
> >     out:
> >       qemu_co_mutex_unlock(&s->lock);
> > +
> > +    ret = bdrv_co_flush(bs);
>
> Oops that's wrong. Here we probably rewrite previous error of 
> bdrv_truncate stored in ret variable.

You absolutely right, we have missed this point.

Good catch!

> > +    if (ret < 0) {
> > +        res->check_errors++;
> > +    }
> > +
> >       return ret;
> >   }