Re: [Qemu-devel] [PATCH 11/24] block: introduce persistent dirty bitmaps

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

11.02.2017 02:20, John Snow wrote:
>
> On 02/03/2017 04:40 AM, Vladimir Sementsov-Ogievskiy wrote:
>> New field BdrvDirtyBitmap.persistent means, that bitmap should be saved
>> on bdrv_close, using format driver. Format driver should maintain bitmap
>> storing.
>>
>> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>> Reviewed-by: Max Reitz <mreitz@redhat.com>
>> ---
>>   block.c                      | 32 ++++++++++++++++++++++++++++++++
>>   block/dirty-bitmap.c         | 26 ++++++++++++++++++++++++++
>>   block/qcow2-bitmap.c         |  1 +
>>   include/block/block.h        |  1 +
>>   include/block/block_int.h    |  2 ++
>>   include/block/dirty-bitmap.h |  6 ++++++
>>   6 files changed, 68 insertions(+)
>>
>> diff --git a/block.c b/block.c
>> index 56f030c562..970e4ca50e 100644
>> --- a/block.c
>> +++ b/block.c
>> @@ -2321,6 +2321,7 @@ void bdrv_reopen_abort(BDRVReopenState *reopen_state)
>>   static void bdrv_close(BlockDriverState *bs)
>>   {
>>       BdrvAioNotifier *ban, *ban_next;
>> +    Error *local_err = NULL;
>>   
>>       assert(!bs->job);
>>       assert(!bs->refcnt);
>> @@ -2329,6 +2330,12 @@ static void bdrv_close(BlockDriverState *bs)
>>       bdrv_flush(bs);
>>       bdrv_drain(bs); /* in case flush left pending I/O */
>>   
>> +    bdrv_store_persistent_dirty_bitmaps(bs, &local_err);
>> +    if (local_err != NULL) {
>> +        error_report_err(local_err);
>> +        error_report("Persistent bitmaps are lost for node '%s'",
>> +                     bdrv_get_device_or_node_name(bs));
>> +    }
> Ouch! I guess there's not much else we can do here, eh?
>
>>       bdrv_release_named_dirty_bitmaps(bs);
>>       assert(QLIST_EMPTY(&bs->dirty_bitmaps));
>>   
>> @@ -4107,3 +4114,28 @@ void bdrv_load_autoloading_dirty_bitmaps(BlockDriverState *bs, Error **errp)
>>           bs->drv->bdrv_load_autoloading_dirty_bitmaps(bs, errp);
>>       }
>>   }
>> +
>> +void bdrv_store_persistent_dirty_bitmaps(BlockDriverState *bs, Error **errp)
>> +{
>> +    BlockDriver *drv = bs->drv;
>> +
>> +    if (!bdrv_has_persistent_bitmaps(bs)) {
>> +        return;
>> +    }
>> +
>> +    if (!drv) {
>> +        error_setg_errno(errp, ENOMEDIUM,
>> +                         "Can't store persistent bitmaps to %s",
>> +                         bdrv_get_device_or_node_name(bs));
>> +        return;
>> +    }
>> +
>> +    if (!drv->bdrv_store_persistent_dirty_bitmaps) {
>> +        error_setg_errno(errp, ENOTSUP,
>> +                         "Can't store persistent bitmaps to %s",
>> +                         bdrv_get_device_or_node_name(bs));
>> +        return;
>> +    }
>> +
> I suppose this is for the case for where we have added a persistent
> bitmap during runtime, but the driver does not support it?
>
> I'd rather fail this type of thing earlier if possible, but I'm not that
> far in your series yet.

qmp bitmap add checks for availability of 
drv->bdrv_can_store_new_dirty_bitmap,
and loaded bitmaps of course should be attached to bds with appropriate 
driver.
So, it is mostly a paranoic check.

>
>> +    drv->bdrv_store_persistent_dirty_bitmaps(bs, errp);
>> +}
>> diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
>> index 2d27494dc7..4d026df1bd 100644
>> --- a/block/dirty-bitmap.c
>> +++ b/block/dirty-bitmap.c
>> @@ -44,6 +44,7 @@ struct BdrvDirtyBitmap {
>>       int64_t size;               /* Size of the bitmap (Number of sectors) */
>>       bool disabled;              /* Bitmap is read-only */
>>       int active_iterators;       /* How many iterators are active */
>> +    bool persistent;            /* bitmap must be saved to owner disk image */
>>       bool autoload;              /* For persistent bitmaps: bitmap must be
>>                                      autoloaded on image opening */
>>       QLIST_ENTRY(BdrvDirtyBitmap) list;
>> @@ -73,6 +74,7 @@ void bdrv_dirty_bitmap_make_anon(BdrvDirtyBitmap *bitmap)
>>       g_free(bitmap->name);
>>       bitmap->name = NULL;
>>   
>> +    bitmap->persistent = false;
>>       bitmap->autoload = false;
>>   }
>>   
>> @@ -242,6 +244,8 @@ BdrvDirtyBitmap *bdrv_dirty_bitmap_abdicate(BlockDriverState *bs,
>>       bitmap->name = NULL;
>>       successor->name = name;
>>       bitmap->successor = NULL;
>> +    successor->persistent = bitmap->persistent;
>> +    bitmap->persistent = false;
>>       successor->autoload = bitmap->autoload;
>>       bitmap->autoload = false;
>>       bdrv_release_dirty_bitmap(bs, bitmap);
>> @@ -556,3 +560,25 @@ bool bdrv_dirty_bitmap_get_autoload(const BdrvDirtyBitmap *bitmap)
>>   {
>>       return bitmap->autoload;
>>   }
>> +
>> +void bdrv_dirty_bitmap_set_persistance(BdrvDirtyBitmap *bitmap, bool persistent)
>> +{
>> +    bitmap->persistent = persistent;
>> +}
>> +
>> +bool bdrv_dirty_bitmap_get_persistance(BdrvDirtyBitmap *bitmap)
>> +{
>> +    return bitmap->persistent;
>> +}
>> +
>> +bool bdrv_has_persistent_bitmaps(BlockDriverState *bs)
>> +{
>> +    BdrvDirtyBitmap *bm;
>> +    QLIST_FOREACH(bm, &bs->dirty_bitmaps, list) {
>> +        if (bm->persistent) {
>> +            return true;
>> +        }
>> +    }
>> +
>> +    return false;
>> +}
> Probably not worth optimizing.
>
>> diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c
>> index bcbb0491ee..9af658a0f4 100644
>> --- a/block/qcow2-bitmap.c
>> +++ b/block/qcow2-bitmap.c
>> @@ -707,6 +707,7 @@ void qcow2_load_autoloading_dirty_bitmaps(BlockDriverState *bs, Error **errp)
>>                   goto fail;
>>               }
>>   
>> +            bdrv_dirty_bitmap_set_persistance(bitmap, true);
>>               bdrv_dirty_bitmap_set_autoload(bitmap, true);
>>               bm->flags |= BME_FLAG_IN_USE;
>>               created_dirty_bitmaps =
>> diff --git a/include/block/block.h b/include/block/block.h
>> index 154ac7f955..0a20d68f0f 100644
>> --- a/include/block/block.h
>> +++ b/include/block/block.h
>> @@ -552,5 +552,6 @@ void bdrv_add_child(BlockDriverState *parent, BlockDriverState *child,
>>   void bdrv_del_child(BlockDriverState *parent, BdrvChild *child, Error **errp);
>>   
>>   void bdrv_load_autoloading_dirty_bitmaps(BlockDriverState *bs, Error **errp);
>> +void bdrv_store_persistent_dirty_bitmaps(BlockDriverState *bs, Error **errp);
>>   
>>   #endif
>> diff --git a/include/block/block_int.h b/include/block/block_int.h
>> index 6b2b50c6a2..c3505da56e 100644
>> --- a/include/block/block_int.h
>> +++ b/include/block/block_int.h
>> @@ -322,6 +322,8 @@ struct BlockDriver {
>>   
>>       void (*bdrv_load_autoloading_dirty_bitmaps)(BlockDriverState *bs,
>>                                                   Error **errp);
>> +    void (*bdrv_store_persistent_dirty_bitmaps)(BlockDriverState *bs,
>> +                                                Error **errp);
>>   
>>       QLIST_ENTRY(BlockDriver) list;
>>   };
>> diff --git a/include/block/dirty-bitmap.h b/include/block/dirty-bitmap.h
>> index 45a389a20a..8dbd16b040 100644
>> --- a/include/block/dirty-bitmap.h
>> +++ b/include/block/dirty-bitmap.h
>> @@ -77,4 +77,10 @@ void bdrv_dirty_bitmap_deserialize_finish(BdrvDirtyBitmap *bitmap);
>>   
>>   void bdrv_dirty_bitmap_set_autoload(BdrvDirtyBitmap *bitmap, bool autoload);
>>   bool bdrv_dirty_bitmap_get_autoload(const BdrvDirtyBitmap *bitmap);
>> +void bdrv_dirty_bitmap_set_persistance(BdrvDirtyBitmap *bitmap,
>> +                                                bool persistent);
>> +bool bdrv_dirty_bitmap_get_persistance(BdrvDirtyBitmap *bitmap);
>> +
>> +bool bdrv_has_persistent_bitmaps(BlockDriverState *bs);
>> +
>>   #endif
>>
> Reviewed-by: John Snow <jsnow@redhat.com>


-- 
Best regards,
Vladimir