target: reject COMPARE_AND_WRITE if emulate_caw is not set

In struct se_dev_attrib, there is a field emulate_caw exposed
as a /sys/kernel/config/target/core/$HBA/$DEV/attrib/.

If this field is set zero, it means the corresponding struct se_device
does not support the scsi cmd COMPARE_AND_WRITE

In function sbc_parse_cdb(), go ahead and reject scsi COMPARE_AND_WRITE
if emulate_caw is not set, because it has been explicitly disabled
from user-space.

(Make pr_err ratelimited - nab)

Signed-off-by: Jiang Yi <jiangyilism@gmail.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

diff --git a/drivers/target/target_core_sbc.c b/drivers/target/target_core_sbc.c
index 4316f7b..ff4a6ec 100644 (file)
--- 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_ratelimited("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