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

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

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 <vsementsov@virtuozzo.com>
>> ---
>>   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.

>> +    }
>> +
>>       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 <andrey.shinkevich@virtuozzo.com>


-- 
Best regards,
Vladimir