Re: [Qemu-devel] [5860] Cleanup {alloc|get}_cluster_offset() (Gleb Natapov)

[Gleb Natapov]

On Thu, Dec 11, 2008 at 02:21:44PM +0100, Alexander Graf wrote:
> Gleb,
>
> do you have a Novell bugzilla account, so I can add you to the bug?  
Just opened one: glebn.

> Kevin apparently used some of his spare time (he's on vacation) to look 
> at this as well.
>
> Alex
>
> On 11.12.2008, at 12:00, Gleb Natapov wrote:
>
>> On Wed, Dec 10, 2008 at 08:38:19AM -0600, Anthony Liguori wrote:
>>> Hi Gleb,
>>>
>>> Anthony Liguori wrote:
>>>> Revision: 5860
>>>>          http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=5860
>>>> Author:   aliguori
>>>> Date:     2008-12-02 20:11:27 +0000 (Tue, 02 Dec 2008)
>>>>
>>>
>>> According to https://bugzilla.novell.com/show_bug.cgi?id=457957, this
>>> changeset breaks compressed qcow2 on write and savevm.
>>>
>>> Can you please look into this?
>>>
>> Alexander, can you try the patch below?
>>
>>
>> diff --git a/block-qcow2.c b/block-qcow2.c
>> index b3b5f8f..d8ac647 100644
>> --- a/block-qcow2.c
>> +++ b/block-qcow2.c
>> @@ -620,6 +620,9 @@ static int count_contiguous_clusters(uint64_t  
>> nb_clusters, int cluster_size,
>>     int i;
>>     uint64_t offset = be64_to_cpu(l2_table[0]) & ~mask;
>>
>> +    if (!offset)
>> +        return 0;
>> +
>>     for (i = 0; i < nb_clusters; i++)
>>         if (offset + i * cluster_size != (be64_to_cpu(l2_table[i]) &  
>> ~mask))
>>             break;
>> @@ -981,6 +984,12 @@ static uint64_t  
>> alloc_cluster_offset(BlockDriverState *bs,
>>     /* how many available clusters ? */
>>
>>     while (i < nb_clusters) {
>> +        i += count_contiguous_clusters(nb_clusters - i, s- 
>> >cluster_size,
>> +                &l2_table[l2_index + i], 0);
>> +
>> +        if(be64_to_cpu(l2_table[l2_index + i]))
>> +            break;
>> +
>>         i += count_contiguous_free_clusters(nb_clusters - i,
>>                 &l2_table[l2_index + i]);
>>
>> @@ -989,12 +998,6 @@ static uint64_t  
>> alloc_cluster_offset(BlockDriverState *bs,
>>         if ((cluster_offset & QCOW_OFLAG_COPIED) ||
>>                 (cluster_offset & QCOW_OFLAG_COMPRESSED))
>>             break;
>> -
>> -        i += count_contiguous_clusters(nb_clusters - i, s- 
>> >cluster_size,
>> -                &l2_table[l2_index + i], 0);
>> -
>> -        if(be64_to_cpu(l2_table[l2_index + i]))
>> -            break;
>>     }
>>     nb_clusters = i;
>>
>> --
>>                      Gleb.

--
                        Gleb.