Le Friday 17 Jan 2014 à 15:14:52 (+0100), Kevin Wolf a écrit :
> When there is a format driver between the backend, it's not guaranteed
> that exposing the opt_transfer_length for the format driver results in
> the optimal requests (because of fragmentation etc.), but it can't make
> things worse, so let's just do it.
>
> Signed-off-by: Kevin Wolf <kw...@redhat.com>
> Reviewed-by: Wenchao Xia <xiaw...@linux.vnet.ibm.com>
> Reviewed-by: Max Reitz <mre...@redhat.com>
> ---
> block.c | 20 +++++++++++++++++++-
> 1 file changed, 19 insertions(+), 1 deletion(-)
>
> diff --git a/block.c b/block.c
> index 99e69da..20f85cb 100644
> --- a/block.c
> +++ b/block.c
> @@ -485,7 +485,25 @@ static int bdrv_refresh_limits(BlockDriverState *bs)
>
> memset(&bs->bl, 0, sizeof(bs->bl));
>
> - if (drv && drv->bdrv_refresh_limits) {
> + if (!drv) {
> + return 0;
> + }
> +
> + /* Take some limits from the children as a default */
> + if (bs->file) {
> + bdrv_refresh_limits(bs->file);
> + bs->bl.opt_transfer_length = bs->file->bl.opt_transfer_length;
> + }
> +
> + if (bs->backing_hd) {
> + bdrv_refresh_limits(bs->backing_hd);
> + bs->bl.opt_transfer_length =
> + MAX(bs->bl.opt_transfer_length,
> + bs->backing_hd->bl.opt_transfer_length);
> + }
> +
> + /* Then let the driver override it */
> + if (drv->bdrv_refresh_limits) {
> return drv->bdrv_refresh_limits(bs);
> }
Reviewed-by: Benoît Canet <ben...@irqsave.net>
>
> --
> 1.8.1.4
>
>
