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

[Peter Lieven <pl@kamp.de>]

On 27.10.2014 09:28, Max Reitz wrote:
> 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 <pl@kamp.de>
>> ---
>>   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:

Would you give it another name?

Peter