Eric,
Now for a really serious issue: in sbc3r24
TPRZ == "thin provisioning read zeros".
SBC-3 uses the shorter variant of the plural of
zero. [ACS-2 uses both zeros and zeroes :-)]

The reason I point that out (apart from trying to
distract James B. from another dispute) is that
you are introducing a new module option called
"unmap_zeroes". I prefer the shorter form.


When I tried to combine your patch on top of Martin's
I needed to do a hand merge (since I'm "gitless") onto
lk 2.6.35 . Both of you picked almost the same lines
to change. Attached is the result of my patch merge
against lk 2.6.35 . It may not be tab clean.

With that combined patch I checked a real SSD that
does TPRZ against the scsi_debug virtual SSD and it
looked okay with my utilities.


SCSI WRITE SAME does have one interesting quirk that
Martin may like to consider. If the "number of
logical blocks" field is zero, then that implies write
to the end of the LU!! Madness when you think about it.
libata's SCSI WRITE SAME translation takes the zero
number of LBs literally and does nothing I guess
(when the UNMAP bit is given).

Doug Gilbert



On 10-08-23 03:24 PM, Eric Sandeen wrote:
> Add TPRZ support to scsi_debug; i.e. return zero for
> unmapped blocks.
>
> Rather than checking for unmapped blocks at
> read time, this just zeroes them on the backing store
> at unmap time so it behaves the same way.
>
> This also adds a module parameter to disable it, since
> some SSDs have this behavior.
>
> Signed-off-by: Eric Sandeen<sandeen@redhat.com>

Acked-by: Douglas Gilbert <dgilbert@interlog.com>