On Wed, Feb 19, 2014 at 09:42:26PM +0800, Fam Zheng wrote:
> This reuses the new bdrv_drop_intermediate.
>
> Signed-off-by: Fam Zheng <f...@redhat.com>
> ---
> block/stream.c | 30 +-----------------------------
> 1 file changed, 1 insertion(+), 29 deletions(-)
>
> diff --git a/block/stream.c b/block/stream.c
> index dd0b4ac..9cdcf0e 100644
> --- a/block/stream.c
> +++ b/block/stream.c
> @@ -51,34 +51,6 @@ static int coroutine_fn stream_populate(BlockDriverState
> *bs,
> return bdrv_co_copy_on_readv(bs, sector_num, nb_sectors, &qiov);
> }
>
> -static void close_unused_images(BlockDriverState *top, BlockDriverState
> *base,
> - const char *base_id)
> -{
> - BlockDriverState *intermediate;
> - intermediate = top->backing_hd;
> -
> - /* Must assign before bdrv_delete() to prevent traversing dangling
> pointer
> - * while we delete backing image instances.
> - */
> - top->backing_hd = base;
> -
> - while (intermediate) {
> - BlockDriverState *unused;
> -
> - /* reached base */
> - if (intermediate == base) {
> - break;
> - }
> -
> - unused = intermediate;
> - intermediate = intermediate->backing_hd;
> - unused->backing_hd = NULL;
> - bdrv_unref(unused);
> - }
> -
> - bdrv_refresh_limits(top);
> -}
> -
> static void coroutine_fn stream_run(void *opaque)
> {
> StreamBlockJob *s = opaque;
> @@ -192,7 +164,7 @@ wait:
> }
> }
> ret = bdrv_change_backing_file(bs, base_id, base_fmt);
This is redundant if bdrv_drop_intermediate() is used, and can be
removed.
> - close_unused_images(bs, base, base_id);
> + bdrv_drop_intermediate(bs, bs->backing_hd, base);
Previously, if base == NULL and base_id == NULL, that meant that we
were streaming from the very first backing file all the way up to the
active layer. When close_unused_images() was called with base ==
NULL, the BDS chain was flattened and the active layer became all that
was left.
By calling bdrv_drop_intermediate() with base == NULL, we get the same
behavior, so that is OK.
What about if base != NULL here? It still works OK, but now 'base' is
really 'bs->backing_hd'. But I don't think we care anymore in this
function, or in the streaming block job, so I think it is OK.
> }
>
> qemu_vfree(buf);
> --
> 1.8.5.4
>
>
