Am 12.01.2010 19:13, schrieb Christoph Hellwig:
> The backing device is only modified from bdrv_commit. So instead of
> flushing it every time bdrv_flush is called for the front-end device
> only flush it after we're written data to it in bdrv_commit.
>
> Also flush the frontend image if we have a make_empty method that
> possibly writes to it.
>
> Signed-off-by: Christoph Hellwig <h...@lst.de>
>
> Index: qemu/block.c
> ===================================================================
> --- qemu.orig/block.c 2010-01-12 19:08:07.363003775 +0100
> +++ qemu/block.c 2010-01-12 19:09:10.836255948 +0100
> @@ -589,6 +589,7 @@ int bdrv_commit(BlockDriverState *bs)
> BlockDriver *drv = bs->drv;
> int64_t i, total_sectors;
> int n, j;
> + int ret = 0;
> unsigned char sector[512];
>
> if (!drv)
> @@ -620,10 +621,18 @@ int bdrv_commit(BlockDriverState *bs)
> }
> }
>
> - if (drv->bdrv_make_empty)
> - return drv->bdrv_make_empty(bs);
> + if (drv->bdrv_make_empty) {
> + ret = drv->bdrv_make_empty(bs);
> + bdrv_flush(bs);
> + }
Indentation is off here (but it already was before the patch). The logic
looks good to me now.
Kevin
