On 17.09.2015 15:48, Kevin Wolf wrote:
> After bdrv_swap(), some fields must be moved back to their original BDS
> to compensate for the effects that a swap of the contents of the objects
> has while keeping the old addresses. Other fields must be moved back
> because they should logically be moved and must stay on top
>
> When replacing bdrv_swap() with operations changing the pointers in the
> parents, we only need the latter and must avoid swapping the former.
> Split the function accordingly.
>
> Signed-off-by: Kevin Wolf <kw...@redhat.com>
> ---
> block.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/block.c b/block.c
> index 743f82e..7930f3c 100644
> --- a/block.c
> +++ b/block.c
> @@ -1984,6 +1984,8 @@ static void bdrv_rebind(BlockDriverState *bs)
> }
> }
>
> +/* Fields that need to stay with the top-level BDS, no matter whether the
> + * address of the top-level BDS stays the same or not. */
> static void bdrv_move_feature_fields(BlockDriverState *bs_dest,
> BlockDriverState *bs_src)
> {
> @@ -2019,7 +2021,13 @@ static void bdrv_move_feature_fields(BlockDriverState
> *bs_dest,
>
> /* dirty bitmap */
> bs_dest->dirty_bitmaps = bs_src->dirty_bitmaps;
> +}
>
> +/* Fields that only need to be swapped if the contents of BDSes is swapped
> + * rather than pointers being changed in the parents. */
> +static void bdrv_move_reference_fields(BlockDriverState *bs_dest,
> + BlockDriverState *bs_src)
> +{
> /* reference count */
> bs_dest->refcnt = bs_src->refcnt;
> I'm not sure whether the op blockers should be moved in this function... I think they should be moved in bdrv_move_feasture_fields(), because they generally depend on the position within the node graph and not on the BDS itself, don't they? Max > @@ -2090,6 +2098,10 @@ void bdrv_swap(BlockDriverState *bs_new, > BlockDriverState *bs_old) > bdrv_move_feature_fields(bs_old, bs_new); > bdrv_move_feature_fields(bs_new, &tmp); > > + bdrv_move_reference_fields(&tmp, bs_old); > + bdrv_move_reference_fields(bs_old, bs_new); > + bdrv_move_reference_fields(bs_new, &tmp); > + > /* bs_new must remain unattached */ > assert(!bs_new->blk); > >
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