target/sbc: Make internal DIF emulation honor ->prot_checks

The internal DIF emulation was not honoring se_cmd->prot_checks for
the WRPROTECT/RDPROTECT == 0x3 case, so sbc_dif_v1_verify() has been
updated to follow which checks have been calculated based on
WRPROTECT/RDPROTECT in sbc_set_prot_op_checks().
Reviewed-by: Martin Petersen <martin.petersen@oracle.com>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/target_core_sbc.c

@@ -1230,6 +1230,9 @@ sbc_dif_v1_verify(struct se_cmd *cmd, struct se_dif_v1_tuple *sdt,
 	int block_size = dev->dev_attrib.block_size;
 	__be16 csum;
 
+	if (!(cmd->prot_checks & TARGET_DIF_CHECK_GUARD))
+		goto check_ref;
+
 	csum = cpu_to_be16(crc_t10dif(p, block_size));
 
 	if (sdt->guard_tag != csum) {
@@ -1239,6 +1242,10 @@ sbc_dif_v1_verify(struct se_cmd *cmd, struct se_dif_v1_tuple *sdt,
 		return TCM_LOGICAL_BLOCK_GUARD_CHECK_FAILED;
 	}
 
+check_ref:
+	if (!(cmd->prot_checks & TARGET_DIF_CHECK_REFTAG))
+		return 0;
+
 	if (cmd->prot_type == TARGET_DIF_TYPE1_PROT &&
 	    be32_to_cpu(sdt->ref_tag) != (sector & 0xffffffff)) {
 		pr_err("DIFv1 Type 1 reference failed on sector: %llu tag: 0x%08x"