Hi Greg,

Could you help pulling c749301ebee82eb5e97dec14b6ab31a4aabe37a6 into
the stable branches in which 17b49bcbf8351d3dbe57204468ac34f033ed60bc
has been pulled? Thanks!

Regards,
Tom

On Sat, 27 Nov 2021 at 05:21, Tom Yan [off-list ref] wrote:

Ahh, looks like the required change to sd
(c749301ebee82eb5e97dec14b6ab31a4aabe37a6) has been added to upstream
but somehow got missed when 17b49bcbf8351d3dbe57204468ac34f033ed60bc
was pulled into stable...

On Sat, 27 Nov 2021 at 05:11, Tom Yan [off-list ref] wrote:

quoted

Hi,

So with 17b49bcbf8351d3dbe57204468ac34f033ed60bc (upstream),
scsi_mode_sense now returns -EINVAL if len < 8, yet in sd, the first mode
sense attempted by sd_read_cache_type() is done with (first_)len being
4, which results in the failure of the attempt.

Since the commit is merged into stable, my SATA drive (that has
volatile write cache) is assumed to be a "write through" drive after I
upgraded from 5.15.4 to 5.15.5, as libata sets use_10_for_ms to 1.

Since sd does not (get to) determine which mode sense command to use,
should scsi_mode_sense at least accept a special value 0 (which
first_len would be set to), which is use to refers to the minimum len
to use for mode sense 6 and 10 respectively (i.e. 4 or 8)?

Regards,
Tom