Re: [PATCH v2 07/22] migration/block-dirty-bitmap: simplify dirty_bitmap_load_complete

[Vladimir Sementsov-Ogievskiy]

19.02.2020 18:30, Vladimir Sementsov-Ogievskiy wrote:
> 18.02.2020 17:26, Andrey Shinkevich wrote:
> > On 17/02/2020 18:02, Vladimir Sementsov-Ogievskiy wrote:
> > > bdrv_enable_dirty_bitmap_locked() call does nothing, as if we are in
> > > postcopy, bitmap successor must be enabled, and reclaim operation will
> > > enable the bitmap.
> > >
> > > So, actually we need just call _reclaim_ in both if branches, and
> > > making differences only to add an assertion seems not really good. The
> > > logic becomes simple: on load complete we do reclaim and that's all.
> > >
> > > Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
> > > ---
> > >   migration/block-dirty-bitmap.c | 25 ++++---------------------
> > >   1 file changed, 4 insertions(+), 21 deletions(-)
> > >
> > > diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
> > > index 440c41cfca..9cc750d93b 100644
> > > --- a/migration/block-dirty-bitmap.c
> > > +++ b/migration/block-dirty-bitmap.c
> > > @@ -535,6 +535,10 @@ static void dirty_bitmap_load_complete(QEMUFile *f, 
> > > DBMLoadState *s)
> > >       qemu_mutex_lock(&s->lock);
> > > +    if (bdrv_dirty_bitmap_has_successor(s->bitmap)) {
> > What about making it sure?
> >             assert(!s->bitmap->successor->disabled);
>
> I'm afraid we can't as BdrvDirtyBitmap is not public structure
>
> > > +        bdrv_reclaim_dirty_bitmap(s->bitmap, &error_abort);
>
> But we can assert that resulting bitmap is enabled.

Or not, as bitmap may be not yet enabled, if guest is not yet started.

> > > +    }
> > > +
> > >       for (item = s->enabled_bitmaps; item; item = g_slist_next(item)) {
> > >           LoadBitmapState *b = item->data;
> > > @@ -544,27 +548,6 @@ static void dirty_bitmap_load_complete(QEMUFile *f, 
> > > DBMLoadState *s)
> > >           }
> > >       }
> > > -    if (bdrv_dirty_bitmap_has_successor(s->bitmap)) {
> > > -        bdrv_dirty_bitmap_lock(s->bitmap);
> > > -        if (s->enabled_bitmaps == NULL) {
> > > -            /* in postcopy */
> > > -            bdrv_reclaim_dirty_bitmap_locked(s->bitmap, &error_abort);
> > > -            bdrv_enable_dirty_bitmap_locked(s->bitmap);
> > > -        } else {
> > > -            /* target not started, successor must be empty */
> > > -            int64_t count = bdrv_get_dirty_count(s->bitmap);
> > > -            BdrvDirtyBitmap *ret = bdrv_reclaim_dirty_bitmap_locked(s->bitmap,
> > > -                                                                    NULL);
> > > -            /* bdrv_reclaim_dirty_bitmap can fail only on no successor (it
> > > -             * must be) or on merge fail, but merge can't fail when second
> > > -             * bitmap is empty
> > > -             */
> > > -            assert(ret == s->bitmap &&
> > > -                   count == bdrv_get_dirty_count(s->bitmap));
> > > -        }
> > > -        bdrv_dirty_bitmap_unlock(s->bitmap);
> > > -    }
> > > -
> > >       qemu_mutex_unlock(&s->lock);
> > >   }
> >
> > Reviewed-by: Andrey Shinkevich <address@hidden>


--
Best regards,
Vladimir