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Date: Fri, 13 Sep 2013 11:10:17 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [PULL 39/42] block: look for zero blocks in
	bs->file
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To: Peter Lieven <lieven-lists@dlhnet.de>
Cc: Anthony Liguori <anthony@codemonkey.ws>, Peter Lieven <pl@kamp.de>, qemu-devel@nongnu.org, Stefan Hajnoczi <stefanha@redhat.com>

Il 13/09/2013 11:08, Peter Lieven ha scritto:
> On 13.09.2013 10:00, Peter Lieven wrote:
>> On 06.09.2013 17:39, Stefan Hajnoczi wrote:
>>> From: Paolo Bonzini <pbonzini@redhat.com>
>>>
>>> Reviewed-by: Eric Blake <eblake@redhat.com>
>>> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>>> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
>>> ---
>>>   block.c | 16 +++++++++++++++-
>>>   1 file changed, 15 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/block.c b/block.c
>>> index 3c39769..a325efc 100644
>>> --- a/block.c
>>> +++ b/block.c
>>> @@ -3075,7 +3075,7 @@ static int64_t coroutine_fn
>>> bdrv_co_get_block_status(BlockDriverState *bs,
>>>   {
>>>       int64_t length;
>>>       int64_t n;
>>> -    int64_t ret;
>>> +    int64_t ret, ret2;
>>>         length = bdrv_getlength(bs);
>>>       if (length < 0) {
>>> @@ -3117,6 +3117,20 @@ static int64_t coroutine_fn
>>> bdrv_co_get_block_status(BlockDriverState *bs,
>>>               }
>>>           }
>>>       }
>>> +
>>> +    if (bs->file &&
>>> +        (ret & BDRV_BLOCK_DATA) && !(ret & BDRV_BLOCK_ZERO) &&
>>> +        (ret & BDRV_BLOCK_OFFSET_VALID)) {
>>> +        ret2 = bdrv_co_get_block_status(bs->file, ret >>
>>> BDRV_SECTOR_BITS,
>>> +                                        *pnum, pnum);
>>> +        if (ret2 >= 0) {
>>> +            /* Ignore errors.  This is just providing extra
>>> information, it
>>> +             * is useful but not necessary.
>>> +             */
>>> +            ret |= (ret2 & BDRV_BLOCK_ZERO);
>>> +        }
>>> +    }
>>> +
>>>       return ret;
>>>   }
>> for allocated blocks in iscsi this actually leads to 2 call outs to
>> iscsi_get_block_status.
>>
>> because the raw driver passes the get_block_status request to bs->file.
>>
> correct patch?

Correct but a bit hackish... Stefan, Kevin, any ideas?

Paolo

> @@ -3119,9 +3167,8 @@ static int64_t coroutine_fn
> bdrv_co_get_block_status(BlockDriverState *bs,
>          }
>      }
> 
> -    if (bs->file &&
> -        (ret & BDRV_BLOCK_DATA) && !(ret & BDRV_BLOCK_ZERO) &&
> -        (ret & BDRV_BLOCK_OFFSET_VALID)) {
> +    if (bs->file && (ret & BDRV_BLOCK_DATA) && !(ret & BDRV_BLOCK_ZERO) &&
> +        (ret & BDRV_BLOCK_OFFSET_VALID) && bs->drv !=
> bdrv_find_format("raw")) {
>          ret2 = bdrv_co_get_block_status(bs->file, ret >> BDRV_SECTOR_BITS,
>                                          *pnum, pnum);
>          if (ret2 >= 0) {
>