Re: [Qemu-block] [PATCH v2] qcow2: discard bitmap when removed

[Andrey Shinkevich]

On 08/04/2019 22:03, Max Reitz wrote:
> On 28.02.19 10:26, Andrey Shinkevich wrote:
>> When a bitmap is removed, we can clean some space on the disk. The size
>> of a cluster may be larger, so is the size of the bitmap that includes
>> many clusters. Some bitmaps can be as large as tens of megabytes.
>> The flag QCOW2_DISCARD_ALWAYS allows a call to the raw_co_pdiscard()
>> that does the actual cleaning of the image on disk, while with the flag
>> QCOW2_DISCARD_OTHER, a reference count of the cluster is updated only.
>>
>> Signed-off-by: Andrey Shinkevich <address@hidden>
>> ---
>> v1: Discard old bitmap directories in QCOW2 image
>>
>> In the first version of the patch, any call to qcow2_free_clusters() in
>> block/qcow2-bitmap.c was with the flag QCOW2_DISCARD_ALWAYS, even in the
>> cases when the cleaned space is insignificant, particularly, in case of
>> bitmap directories.
>> Discussed in the email thread with the message ID
>> <address@hidden>
>>
>>   block/qcow2-bitmap.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> Thanks, changed the commit message to Vladimir’s proposal and applied to
> my block-next branch:
> 
> https://git.xanclic.moe/XanClic/qemu/commits/branch/block-next
> 
> Max
> 

Thank you, Max!
-- 
With the best regards,
Andrey Shinkevich