08.06.2019 1:39, John Snow wrote:
>
>
> On 6/3/19 8:00 AM, Vladimir Sementsov-Ogievskiy wrote:
>> Add functionality to make bitmap temporary anonymous. It will be used
>> to implement bitmap remove transaction action. We need hide bitmap
>> persistence too, as there are should not be unnamed persistent bitmaps.
>>
>
> Ah, so this effectively ... "hides" a bitmap from any further
> transaction actions. It also "hides" it from getting flushed to disk...
> sort of?
>
> The outer loop in store works with bdrv_dirty_bitmap_next, and we'll
> skip this bitmap because it's anonymous/not persistent.
>
> There's a second loop where we iterate bm_list, and we'll skip storing
> this bitmap because that entry won't have an in-memory bitmap associated
> with it in bm_list.
>
> ...But then we'll call update_ext_header_and_dir with the stale entries
> in bm_list?
Hidden is a temprory state, so, we should not go to close() in this state.
It's a state inside a transaction.
Stale entries in list will be marked IN_USE anyway, so there is no damage
anyway.
>
>> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>
>> ---
>> include/block/dirty-bitmap.h | 2 ++
>> block/dirty-bitmap.c | 26 ++++++++++++++++++++++++++
>> 2 files changed, 28 insertions(+)
>>
>> diff --git a/include/block/dirty-bitmap.h b/include/block/dirty-bitmap.h
>> index 8044ace63e..542e437123 100644
>> --- a/include/block/dirty-bitmap.h
>> +++ b/include/block/dirty-bitmap.h
>> @@ -116,5 +116,7 @@ bool bdrv_dirty_bitmap_next_dirty_area(BdrvDirtyBitmap
>> *bitmap,
>> BdrvDirtyBitmap *bdrv_reclaim_dirty_bitmap_locked(BlockDriverState *bs,
>> BdrvDirtyBitmap *bitmap,
>> Error **errp);
>> +void bdrv_dirty_bitmap_hide(BdrvDirtyBitmap *bitmap);
>> +void bdrv_dirty_bitmap_unhide(BdrvDirtyBitmap *bitmap);
>>
>> #endif
>> diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
>> index 49646a30e6..592964635e 100644
>> --- a/block/dirty-bitmap.c
>> +++ b/block/dirty-bitmap.c
>> @@ -35,6 +35,10 @@ struct BdrvDirtyBitmap {
>> bool busy; /* Bitmap is busy, it can't be used via
>> QMP */
>> BdrvDirtyBitmap *successor; /* Anonymous child, if any. */
>> char *name; /* Optional non-empty unique ID */
>> + char *hidden_name; /* Backup of @name for removal transaction
>> + action. Used for hide/unhide API. */
>> + bool hidden_persistent; /* Backup of @persistent for removal
>> transaction
>> + action. */
>> int64_t size; /* Size of the bitmap, in bytes */
>> bool disabled; /* Bitmap is disabled. It ignores all
>> writes to
>> the device */
>> @@ -849,3 +853,25 @@ out:
>> qemu_mutex_unlock(src->mutex);
>> }
>> }
>> +
>> +void bdrv_dirty_bitmap_hide(BdrvDirtyBitmap *bitmap)
>> +{
>> + qemu_mutex_lock(bitmap->mutex);
>> + assert(!bitmap->hidden_name);
>> + bitmap->hidden_name = bitmap->name;
>> + bitmap->hidden_persistent = bitmap->persistent;
>> + bitmap->name = NULL;
>> + bitmap->persistent = false;
>> + qemu_mutex_unlock(bitmap->mutex);
>> +}
>> +
>> +void bdrv_dirty_bitmap_unhide(BdrvDirtyBitmap *bitmap)
>> +{
>> + qemu_mutex_lock(bitmap->mutex);
>> + assert(!bitmap->name);
>> + bitmap->name = bitmap->hidden_name;
>> + bitmap->persistent = bitmap->hidden_persistent;
>> + bitmap->hidden_name = NULL;
>> + bitmap->hidden_persistent = false;
>> + qemu_mutex_unlock(bitmap->mutex);
>> +}
>>
--
Best regards,
Vladimir
