Re: [Qemu-devel] [PATCHv4 3/4] block/iscsi: set max_transfer_length

[Max Reitz <mreitz@redhat.com>]

On 2014-10-16 at 09:54, Peter Lieven wrote:
> the limit of 0xffffff for 16 byte CDBs is intentional to
> avoid overflows on 32-bit architectures.

How is it related to 32 bit? I somehow feel like it has to do something 
with the result of sector_lun2qemu() which involves block_size...

> Signed-off-by: Peter Lieven <pl@kamp.de>
> Reviewed-by: Ronnie Sahlberg <ronniesahlberg@gmail.com>
> ---
>   block/iscsi.c |   12 ++++++++++--
>   1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/block/iscsi.c b/block/iscsi.c
> index 3a01de0..c873d13 100644
> --- a/block/iscsi.c
> +++ b/block/iscsi.c
> @@ -1449,10 +1449,18 @@ static void iscsi_close(BlockDriverState *bs)
>   
>   static void iscsi_refresh_limits(BlockDriverState *bs, Error **errp)
>   {
> -    IscsiLun *iscsilun = bs->opaque;
> -
>       /* We don't actually refresh here, but just return data queried in
>        * iscsi_open(): iscsi targets don't change their limits. */
> +
> +    IscsiLun *iscsilun = bs->opaque;
> +    uint32_t max_xfer_len = iscsilun->use_16_for_rw ? 0xffffff : 0xffff;
> +
> +    if (iscsilun->bl.max_xfer_len) {
> +        max_xfer_len = MIN(max_xfer_len, iscsilun->bl.max_xfer_len);
> +    }
> +
> +    bs->bl.max_transfer_length = sector_lun2qemu(max_xfer_len, iscsilun);
> +
>       if (iscsilun->lbp.lbpu) {
>           if (iscsilun->bl.max_unmap < 0xffffffff) {
>               bs->bl.max_discard = sector_lun2qemu(iscsilun->bl.max_unmap,