Re: [Qemu-devel] [PATCHv5 3/6] block/iscsi: set max_transfer_length

[Max Reitz]

On 2014-10-25 at 18:18, Peter Lieven wrote:
> Copy the max_xfer_len from the BlockLimits VPD or use the
> maximum value fitting in the CDB.
>
> Signed-off-by: Peter Lieven <address@hidden>
> ---
>   block/iscsi.c |   17 +++++++++++++++--
>   1 file changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/block/iscsi.c b/block/iscsi.c
> index 233f462..1ae4add 100644
> --- a/block/iscsi.c
> +++ b/block/iscsi.c
> @@ -297,6 +297,11 @@ static int64_t sector_lun2qemu(int64_t sector, IscsiLun 
> *iscsilun)
>       return sector * iscsilun->block_size / BDRV_SECTOR_SIZE;
>   }
>   
> +static int nb_sectors_lun2qemu(int64_t sector, IscsiLun *iscsilun)
> +{
> +    return MIN(sector_lun2qemu(sector, iscsilun), INT_MAX);
> +}
> +
>   static int64_t sector_qemu2lun(int64_t sector, IscsiLun *iscsilun)
>   {
>       return sector * BDRV_SECTOR_SIZE / iscsilun->block_size;
> @@ -1449,10 +1454,18 @@ 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 ? 0xffffffff : 0xffff;
> +
> +    if (iscsilun->bl.max_xfer_len) {
> +        max_xfer_len = MIN(max_xfer_len, iscsilun->bl.max_xfer_len);
> +    }
> +
> +    bs->bl.max_transfer_length = nb_sectors_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,

Hm, seems strange to have a function called nb_sectors_lun2qemu() not 
only convert values, but also cap the result. But anyway:

Reviewed-by: Max Reitz <address@hidden>