On Wed, Apr 22, 2015 at 08:04:44PM -0400, John Snow wrote:
> +static void block_dirty_bitmap_clear_prepare(BlkTransactionState *common,
> + Error **errp)
> +{
> + BlockDirtyBitmapState *state = DO_UPCAST(BlockDirtyBitmapState,
> + common, common);
> + BlockDirtyBitmap *action;
> +
> + action = common->action->block_dirty_bitmap_clear;
> + state->bitmap = block_dirty_bitmap_lookup(action->node,
> + action->name,
> + &state->bs,
> + &state->aio_context,
> + errp);
> + if (!state->bitmap) {
> + return;
> + }
> +
> + if (bdrv_dirty_bitmap_frozen(state->bitmap)) {
> + error_setg(errp, "Cannot modify a frozen bitmap");
> + return;
> + } else if (!bdrv_dirty_bitmap_enabled(state->bitmap)) {
> + error_setg(errp, "Cannot clear a disabled bitmap");
> + return;
> + }
> +
> + /* AioContext is released in .clean() */
> +}
> +
> +static void block_dirty_bitmap_clear_commit(BlkTransactionState *common)
> +{
> + BlockDirtyBitmapState *state = DO_UPCAST(BlockDirtyBitmapState,
> + common, common);
> + bdrv_clear_dirty_bitmap(state->bitmap);
> +}These semantics don't work in this example: [block-dirty-bitmap-clear, drive-backup] Since drive-backup starts the blockjob in .prepare() but block-dirty-bitmap-clear only clears the bitmap in .commit() the order is wrong. .prepare() has to do something non-destructive, like stashing away the HBitmap and replacing it with an empty one. Then .commit() can discard the old bitmap while .abort() can move the old bitmap back to undo the operation. Stefan
pgpOfYLUaRybo.pgp
Description: PGP signature
