On Fri, 2017-06-02 at 11:45 +0800, Jiang Yi wrote:
> Hi Nic,
>
> in struct se_dev_attrib, there is a field emulate_caw.
>
> If this field is set zero, does it mean that the corresponding struct se_device does not support the scsi cmd COMPARE_AND_WRITE?
>
> Do fields like emulate_tpws, emulate_tpu, emulate_tas... imply "enable support for thin provision write same", "enable support for
> thin provision unmap", "enable support for task aborted status"?
>
> In function sbc_parse_cdb(), it rejects scsi cmd UNMAP if emulate_tpu is not set. So I think we should also reject COMPARE_AND_WRITE if emulate_caw is not set.
>
> I propose a patch:
>
> Signed-off-by: Jiang Yi <jiangyilism@xxxxxxxxx>
> ---
> drivers/target/target_core_sbc.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/target/target_core_sbc.c b/drivers/target/target_core_sbc.c
> index 4316f7b..bdea345 100644
> --- a/drivers/target/target_core_sbc.c
> +++ b/drivers/target/target_core_sbc.c
> @@ -1005,6 +1005,12 @@ sbc_parse_cdb(struct se_cmd *cmd, struct sbc_ops *ops)
> break;
> }
> case COMPARE_AND_WRITE:
> + if (!dev->dev_attrib.emulate_caw) {
> + pr_err("se_device %s/%s (vpd_unit_serial %s) reject COMPARE_AND_WRITE\n",
> + dev->se_hba->backend->ops->name, dev->dev_group.cg_item.ci_name,
> + dev->t10_wwn.unit_serial);
> + return TCM_UNSUPPORTED_SCSI_OPCODE;
> + }
> sectors = cdb[13];
> /*
> * Currently enforce COMPARE_AND_WRITE for a single sector
Applied to target-pending/for-next, with a slightly improved commit log.
Also, all new pr_err() should be pr_err_ratelimited(). Fixed that up
before applying.
Wrt to your comments, I'd be open to consider a wrapper that dumps more
verbose se_device specific information for these types of CDB errors.
It would be a good excuse to convert all of the pr_[err,warn]() to
*_ratelimited() too. ;)
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