Re: [PATCH v6 1/4] libata: Safely overwrite attached page in WRITE SAME xlat

Shaun Tancheff
2016-08-23T08:51:12Z

On Tue, Aug 23, 2016 at 2:53 AM, Tom Yan <tom.ty89@gmail.com> wrote:
> On 23 August 2016 at 06:20, Shaun Tancheff <shaun.tancheff@seagate.com> wrote:
>> On Tue, Aug 23, 2016 at 12:26 AM, Tom Yan <tom.ty89@gmail.com> wrote:
>>
>>> It is always 1 merely because we prefer sticking to that. Say we want
>>> to enable multi-block payload now, it won't be 1 anymore.
>>
>> Sorry, I though that DSM TRIM is using 512 bytes here because
>> WRITE_SAME_16 has a payload of a single logical sector.
>
> Nope, SCSI Write Same commands does not have payload (or in SCSI
> terms, parameter list / data-out buffer).

Hmm. Not sure about T10, but that's not how I read
sd_setup_write_same_cmnd(), it always setups up a transfer of
sector_size for scsi_init_io().

As I understand things, this is how the cmd's sglist is populated and why
this should be using sg_copy_from_buffer() rather than open coding
to the page.
--
Shaun Tancheff