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

[Alexander Ivanov <alexander.ivanov@virtuozzo.com>]

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.

Good point!

As you said in 8/8, now it doesn't matter, but I'll fix it for the patch 
correctness.

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