[stgt] [PATCH] Add an array that describes which opcodes are supported by the RDWR and SHEEPDOG backends.

[ronnie sahlberg]

Ping?

We need something like an array like this so that we can also update
REPORT_SUPPORTED_OPCODES correctly
and have this opcode only return the opcodes that the particular
backend supports.


On Wed, Oct 30, 2013 at 6:44 PM, ronnie sahlberg
<ronniesahlberg at gmail.com> wrote:
> On Sun, Oct 20, 2013 at 6:34 PM, FUJITA Tomonori
> <fujita.tomonori at lab.ntt.co.jp> wrote:
>> On Sat, 12 Oct 2013 07:38:59 -0700
>> Ronnie Sahlberg <ronniesahlberg at gmail.com> wrote:
>>
>>> While RDWR supports all SBC opcodes that TGTD implement SHEEPDOG
>>> only supports a subset and lacks the following opcodes:
>>>             WRITE_VERIFY10/12/16 VERIFY10/12/16 PREFETCH10/16
>>>             WRITE_SAME10/16 UNMAP and ORWRITE
>>>
>>> This allows backends to specify which opcodes it is prepared to process
>>> and which commands should fail with invalid op code
>>> and allows SHEEPDOG backed LUNs to respond with INVALID_OP_CODE
>>> correctly.
>>>
>>> This is most useful for block devices where we have several different backens
>>> and where some backends only support a subset of the commands
>>>
>>> Signed-off-by: Ronnie Sahlberg <ronniesahlberg at gmail.com>
>>> ---
>>>  usr/bs.c          |    8 ++++++++
>>>  usr/bs_rdwr.c     |   51 +++++++++++++++++++++++++++++++++++++++++++++++++++
>>>  usr/bs_sheepdog.c |   38 ++++++++++++++++++++++++++++++++++++++
>>>  usr/scsi.c        |    6 ++++++
>>>  usr/tgtd.h        |    1 +
>>>  5 files changed, 104 insertions(+), 0 deletions(-)
>>
>> Why backend store's bs_cmd_submit cannot return a proper error and
>> sbr_rc returns that error to an initiator?
>
>
> It could, but this way it is more explicit which opcodes are
> available, and a simple compare of the array between opcodes
> makes it easy for non-bs_rdwr backend developers to see the delta
> between their backend and rdwr.
>
> A second reason is for a followup patch.
> The followup patch will use this array so that it can prune which
> opcodes to report back for the REPORT_SUPPORTED_OPCODE opcode.
> So that when you issue that command to a sheepdog LUN  you get a
> pruned list back that only lists the opcodes that sheepdog supports.
>
>
> regards
> ronnie sahlberg
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