Re: [Qemu-block] [RFC PATCH 2/2] block/dirty-bitmap: implement inconsistent bit

[Eric Blake]

On 2/18/19 12:13 PM, Vladimir Sementsov-Ogievskiy wrote:
> 14.02.2019 2:36, John Snow wrote:
>> Signed-off-by: John Snow <address@hidden>
>> ---
>>   block/dirty-bitmap.c         | 15 +++++++++++++
>>   block/qcow2-bitmap.c         | 42 ++++++++++++++++++-----------------
>>   blockdev.c                   | 43 ++++++++++++++++++++++++++++++++++++
>>   include/block/dirty-bitmap.h |  1 +
>>   4 files changed, 81 insertions(+), 20 deletions(-)

>> +void bdrv_dirty_bitmap_add_inconsistent_hint(Error **errp)
>> +{
>> +    error_append_hint(errp, "Try block-dirty-bitmap-clear to mark this "
>> +                      "bitmap consistent again, or 
>> block-dirty-bitmap-remove "
>> +                      "to delete it.");
> 
> bitmaps created by libvirt (or somebody) are related to some checkpoint. And 
> their name is
> probably (Eric?) related to this checkpoint too. So, clear will never make 
> them consistent..
> Only clear :)
> 
> So, I don't like idea of clearing in-use bitmaps.

It's always possible to delete a bitmap and then create a new one by the
same name, to get the same effect of clearing an in-use bitmap. So let's
start simple and declare that the only valid operation on an
inconsistent bitmap is deletion.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org