Re: [Qemu-devel] [PATCH v3] mirror: correct buf_size

[Paolo Bonzini <pbonzini@redhat.com>]

On 15/05/2015 08:53, Wen Congyang wrote:
> On 05/15/2015 02:45 PM, Paolo Bonzini wrote:
>>
>>
>> On 15/05/2015 03:37, Wen Congyang wrote:
>>> If bus_size is less than 0, the command fails.
>>> If buf_size % granularity is not 0, mirror_free_init() will
>>> do dangerous things.
>>>
>>> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
>>> ---
>>>  block/mirror.c | 6 +++++-
>>>  1 file changed, 5 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/block/mirror.c b/block/mirror.c
>>> index 58f391a..7732f8b 100644
>>> --- a/block/mirror.c
>>> +++ b/block/mirror.c
>>> @@ -671,6 +671,10 @@ static void mirror_start_job(BlockDriverState *bs, BlockDriverState *target,
>>>          return;
>>>      }
>>>  
>>> +    if (buf_size < 0) {
>>
>> This should be <=.
> 
> But commit_active_start() passes 0...

This was changed to granularity by MAX, while it would be 0 after
ROUND_UP.  The right value would be DEFAULT_MIRROR_BUF_SIZE.

block_commit should have an optional buf_size, but for now I guess you
can change a 0 to DEFAULT_MIRROR_BUF_SIZE in mirror_start_job, and let
qmp_drive_mirror do this:

     if (!has_buf_size) {
-        buf_size = DEFAULT_MIRROR_BUF_SIZE;
+        buf_size = 0;
     }

Paolo

> Thanks
> Wen Congyang
> 
>>
>> Jeff, can you adjust when committing?
>>
>> Paolo
>>
>>> +        error_setg(errp, "Invalid parameter '%s'", "buf-size");
>>> +        return;
>>> +    }
>>>  
>>>      s = block_job_create(driver, bs, speed, cb, opaque, errp);
>>>      if (!s) {
>>> @@ -684,7 +688,7 @@ static void mirror_start_job(BlockDriverState *bs, BlockDriverState *target,
>>>      s->is_none_mode = is_none_mode;
>>>      s->base = base;
>>>      s->granularity = granularity;
>>> -    s->buf_size = MAX(buf_size, granularity);
>>> +    s->buf_size = ROUND_UP(buf_size, granularity);
>>>  
>>>      s->dirty_bitmap = bdrv_create_dirty_bitmap(bs, granularity, NULL, errp);
>>>      if (!s->dirty_bitmap) {
>>>
>> .
>>
> 
> 
>