Re: [Qemu-block] [PATCH v3 1/7] block/dirty-bitmaps: add inconsistent bit

[Vladimir Sementsov-Ogievskiy]

06.03.2019 15:25, Vladimir Sementsov-Ogievskiy wrote:
> 01.03.2019 22:15, John Snow wrote:
>> Add an inconsistent bit to dirty-bitmaps that allows us to report a bitmap as
>> persistent but potentially inconsistent, i.e. if we find bitmaps on a qcow2
>> that have been marked as "in use".
>>
>> Signed-off-by: John Snow <address@hidden>
>> ---
>>   qapi/block-core.json         | 13 +++++++++----
>>   include/block/dirty-bitmap.h |  2 ++
>>   block/dirty-bitmap.c         | 19 +++++++++++++++++++
>>   3 files changed, 30 insertions(+), 4 deletions(-)
>>
>> diff --git a/qapi/block-core.json b/qapi/block-core.json
>> index 6e543594b3..e639ef6d1c 100644
>> --- a/qapi/block-core.json
>> +++ b/qapi/block-core.json
>> @@ -467,15 +467,20 @@
>>   #        and cannot be modified via QMP or used by another operation.
>>   #        Replaces `locked` and `frozen` statuses. (since 4.0)
>>   #
>> -# @persistent: true if the bitmap will eventually be flushed to persistent
>> -#              storage (since 4.0)
>> +# @persistent: true if the bitmap was stored on disk, is scheduled to be 
>> stored
>> +#              on disk, or both. (since 4.0)
>> +#
>> +# @inconsistent: true if this is a persistent bitmap that was improperly
>> +#                stored. Implies @persistent to be true; @recording and
>> +#                @busy to be false. This bitmap cannot be used. To remove
>> +#                it, use @block-dirty-bitmap-remove. (Since 4.0)
>>   #
>>   # Since: 1.3
>>   ##
>>   { 'struct': 'BlockDirtyInfo',
>>     'data': {'*name': 'str', 'count': 'int', 'granularity': 'uint32',
>> -           'recording': 'bool', 'busy': 'bool',
>> -           'status': 'DirtyBitmapStatus', 'persistent': 'bool' } }
>> +           'recording': 'bool', 'busy': 'bool', 'status': 
>> 'DirtyBitmapStatus',
>> +           'persistent': 'bool', '*inconsistent': 'bool' } }
>>   ##
>>   # @Qcow2BitmapInfoFlags:
>> diff --git a/include/block/dirty-bitmap.h b/include/block/dirty-bitmap.h
>> index ba8477b73f..bd1b6479df 100644
>> --- a/include/block/dirty-bitmap.h
>> +++ b/include/block/dirty-bitmap.h
>> @@ -68,6 +68,7 @@ void bdrv_dirty_bitmap_deserialize_finish(BdrvDirtyBitmap 
>> *bitmap);
>>   void bdrv_dirty_bitmap_set_readonly(BdrvDirtyBitmap *bitmap, bool value);
>>   void bdrv_dirty_bitmap_set_persistance(BdrvDirtyBitmap *bitmap,
>>                                          bool persistent);
>> +void bdrv_dirty_bitmap_set_inconsistent(BdrvDirtyBitmap *bitmap);
>>   void bdrv_dirty_bitmap_set_busy(BdrvDirtyBitmap *bitmap, bool busy);
>>   void bdrv_merge_dirty_bitmap(BdrvDirtyBitmap *dest, const BdrvDirtyBitmap 
>> *src,
>>                                HBitmap **backup, Error **errp);
>> @@ -91,6 +92,7 @@ bool bdrv_dirty_bitmap_readonly(const BdrvDirtyBitmap 
>> *bitmap);
>>   bool bdrv_has_readonly_bitmaps(BlockDriverState *bs);
>>   bool bdrv_dirty_bitmap_get_autoload(const BdrvDirtyBitmap *bitmap);
>>   bool bdrv_dirty_bitmap_get_persistance(BdrvDirtyBitmap *bitmap);
>> +bool bdrv_dirty_bitmap_inconsistent(const BdrvDirtyBitmap *bitmap);
>>   bool bdrv_dirty_bitmap_busy(BdrvDirtyBitmap *bitmap);
>>   bool bdrv_has_changed_persistent_bitmaps(BlockDriverState *bs);
>>   BdrvDirtyBitmap *bdrv_dirty_bitmap_next(BlockDriverState *bs,
>> diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
>> index 980cae4fa3..9e8630e1ac 100644
>> --- a/block/dirty-bitmap.c
>> +++ b/block/dirty-bitmap.c
>> @@ -46,6 +46,9 @@ struct BdrvDirtyBitmap {
>>                                      and this bitmap must remain unchanged 
>> while
>>                                      this flag is set. */
>>       bool persistent;            /* bitmap must be saved to owner disk 
>> image */
>> +    bool inconsistent;          /* bitmap is persistent, but inconsistent.
>> +                                 * It cannot be used at all in any way, 
>> except
>> +                                 * a QMP user can remove it. */
>>       bool migration;             /* Bitmap is selected for migration, it 
>> should
>>                                      not be stored on the next inactivation
>>                                      (persistent flag doesn't matter until 
>> next
>> @@ -464,6 +467,8 @@ BlockDirtyInfoList 
>> *bdrv_query_dirty_bitmaps(BlockDriverState *bs)
>>           info->recording = bdrv_dirty_bitmap_recording(bm);
>>           info->busy = bdrv_dirty_bitmap_busy(bm);
>>           info->persistent = bm->persistent;
>> +        info->has_inconsistent = bm->inconsistent;
>> +        info->inconsistent = bm->inconsistent;
>>           entry->value = info;
>>           *plist = entry;
>>           plist = &entry->next;
>> @@ -711,6 +716,15 @@ void bdrv_dirty_bitmap_set_persistance(BdrvDirtyBitmap 
>> *bitmap, bool persistent)
>>       qemu_mutex_unlock(bitmap->mutex);
>>   }
>> +/* Called with BQL taken. */
>> +void bdrv_dirty_bitmap_set_inconsistent(BdrvDirtyBitmap *bitmap)
>> +{
>> +    qemu_mutex_lock(bitmap->mutex);
>> +    bitmap->inconsistent = true;
>> +    bitmap->disabled = true;
> 
> Agree, that it worth to assert persistance

Hmm, didn't we want to make it readonly too?

> 
>> +    qemu_mutex_unlock(bitmap->mutex);
>> +}
>> +
>>   /* Called with BQL taken. */
>>   void bdrv_dirty_bitmap_set_migration(BdrvDirtyBitmap *bitmap, bool 
>> migration)
>>   {
>> @@ -724,6 +738,11 @@ bool bdrv_dirty_bitmap_get_persistance(BdrvDirtyBitmap 
>> *bitmap)
>>       return bitmap->persistent && !bitmap->migration;
>>   }
>> +bool bdrv_dirty_bitmap_inconsistent(const BdrvDirtyBitmap *bitmap)
>> +{
>> +    return bitmap->inconsistent;
>> +}
>> +
>>   bool bdrv_has_changed_persistent_bitmaps(BlockDriverState *bs)
>>   {
>>       BdrvDirtyBitmap *bm;
>>
> 
> Reviewed-by: Vladimir Sementsov-Ogievskiy <address@hidden>
> 
> Sorry for a delay, I'm very busy with our rebase to 2.12 :(
> 


-- 
Best regards,
Vladimir