Re: [Qemu-block] [PATCH v4 05/15] block/mirror: don't install backing chain on abort

[Max Reitz]

On 2018-09-05 17:39, John Snow wrote:
> 
> 
> On 09/05/2018 06:40 AM, Max Reitz wrote:
>> On 2018-09-04 19:09, John Snow wrote:
>>> In cases where we abort the block/mirror job, there's no point in
>>> installing the new backing chain before we finish aborting.
>>>
>>> Move this to the "success" portion of mirror_exit.
>>
>> Sounds a bit weird now that you don't do any moving.
>>
> 
> I ought to proofread my commit messages when I make changes...
> 
>>> Signed-off-by: John Snow <address@hidden>
>>> ---
>>>  block/mirror.c | 7 ++-----
>>>  1 file changed, 2 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/block/mirror.c b/block/mirror.c
>>> index cba555b4ef..3365bcfdfb 100644
>>> --- a/block/mirror.c
>>> +++ b/block/mirror.c
>>> @@ -642,7 +642,7 @@ static void mirror_exit(Job *job)
>>>       * required before it could become a backing file of target_bs. */
>>>      bdrv_child_try_set_perm(mirror_top_bs->backing, 0, BLK_PERM_ALL,
>>>                              &error_abort);
>>> -    if (s->backing_mode == MIRROR_SOURCE_BACKING_CHAIN) {
>>> +    if (ret == 0 && s->backing_mode == MIRROR_SOURCE_BACKING_CHAIN) {
>>>          BlockDriverState *backing = s->is_none_mode ? src : s->base;
>>>          if (backing_bs(target_bs) != backing) {
>>>              bdrv_set_backing_hd(target_bs, backing, &local_err);
>>> @@ -659,10 +659,7 @@ static void mirror_exit(Job *job)
>>>      }
>>>  
>>>      if (s->should_complete && ret == 0) {
>>> -        BlockDriverState *to_replace = src;
>>> -        if (s->to_replace) {
>>> -            to_replace = s->to_replace;
>>> -        }
>>> +        BlockDriverState *to_replace = s->to_replace ? s->to_replace : src;
>>>  
>>>          if (bdrv_get_flags(target_bs) != bdrv_get_flags(to_replace)) {
>>>              bdrv_reopen(target_bs, bdrv_get_flags(to_replace), NULL);
>>
>> And this hunk now looks out of place.  Sure, it makes sense, but why is
>> it in this patch now? :-)
>>
>> (Moving it into the next patch would make more sense, I think.)
>>
>> I'd like to give an R-b anyway, but I know that I shouldn't, so I won't.
>>
>> Max
>>
> 
> I have to admit that my appetite for patch purity is just... low. I know
> it's something we care a lot in the QEMU project, but after a number of
> years I'm just not overwhelmed to care about it in any significant capacity.
> 
> I suppose the main argument for this practice is ease of backporting, yes?

I suppose.  And ease of bisecting.  And ease of reviewing.

Max

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