[SLOF] [PATCH] scsi: implement READ (16) command

[Alexey Kardashevskiy]

On 28/09/16 17:03, Nikunj A Dadhania wrote:
> Thomas Huth <thuth at redhat.com> writes:
> 
>> On 28.09.2016 08:37, Nikunj A Dadhania wrote:
>>> For disks bigger than 2TB(512B sector size), read-10 would fail as it is
>>> limited by the block address(4bytes). Add and use SCSI command READ(16)
>>> which has 8bytes block address.
>>>
>>> Signed-off-by: Nikunj A Dadhania <nikunj at linux.vnet.ibm.com>
>>> ---
>>>  slof/fs/scsi-disk.fs    |  2 +-
>>>  slof/fs/scsi-support.fs | 29 +++++++++++++++++++++++++++++
>>>  2 files changed, 30 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/slof/fs/scsi-disk.fs b/slof/fs/scsi-disk.fs
>>> index 2f7d740..83aab89 100644
>>> --- a/slof/fs/scsi-disk.fs
>>> +++ b/slof/fs/scsi-disk.fs
>>> @@ -82,7 +82,7 @@ CREATE cdb 10 allot
>>>      >r rot r> 			                ( block# #blocks addr len )
>>>      2swap                                       ( addr len block# #blocks )
>>>      dup >r
>>> -    cdb scsi-build-read-10                      ( addr len )
>>> +    cdb scsi-build-read-16                      ( addr len )
>>>      r> -rot                                     ( #blocks addr len )
>>>      scsi-dir-read cdb scsi-param-size 10
>>>      retry-scsi-command
>>
>> I'm feeling a little bit uneasy about using READ-16 here
>> unconditionally... IIRC, the scsi stack is also used for USB devices,
>> and these often used to only implement the bare minimum of SCSI
>> commands, i.e. things like READ-16 are likely not supported there.
>> Could you maybe add a check if the block address can not be stored in 4
>> bytes anymore, and only use the READ-16 in that case?
> 
> Yeah sure, that can be done. How about this:
> 
>     cdb                                         ( addr len block# #blocks cdb )
>     max-block-num FFFFFFFF > IF
>         scsi-build-read-16                      ( addr len )
>     ELSE
>         scsi-build-read-10                      ( addr len )
>     THEN
>     r> -rot                                     ( #blocks addr len )


You'll repost the patch, right?


-- 
Alexey