scsi: target: Export fabric driver direct submit settings

This exports the fabric driver's direct submit settings, so users know what
the driver supports. It will be helpful when they are exporting a device
through different targets and one doesn't support direct submission.

The new files allow the fabric to report what submission types they default
to and if they support direct submission:

default_submit_type:

 1 - TARGET_DIRECT_SUBMIT - If the user has not requested a specific value
     then the fabric requests direct submission.

 2 - TARGET_QUEUE_SUBMIT - If the user has not requested a specific value
     then the fabric requests queued submission.

Note that these fabric values are based on what the fabric driver currently
defaults to for compat with exiting setups.

direct_submit_supported:

 0 - The fabric does not support direct submission.

 1 - The fabric supports direct submission.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
Link: https://lore.kernel.org/r/20230928020907.5730-8-michael.christie@oracle.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/target/target_core_fabric_configfs.c

@@ -1065,8 +1065,32 @@ target_fabric_wwn_cmd_completion_affinity_store(struct config_item *item,
 }
 CONFIGFS_ATTR(target_fabric_wwn_, cmd_completion_affinity);
 
+static ssize_t
+target_fabric_wwn_default_submit_type_show(struct config_item *item,
+					   char *page)
+{
+	struct se_wwn *wwn = container_of(to_config_group(item), struct se_wwn,
+					  param_group);
+	return sysfs_emit(page, "%u\n",
+			  wwn->wwn_tf->tf_ops->default_submit_type);
+}
+CONFIGFS_ATTR_RO(target_fabric_wwn_, default_submit_type);
+
+static ssize_t
+target_fabric_wwn_direct_submit_supported_show(struct config_item *item,
+					       char *page)
+{
+	struct se_wwn *wwn = container_of(to_config_group(item), struct se_wwn,
+					  param_group);
+	return sysfs_emit(page, "%u\n",
+			  wwn->wwn_tf->tf_ops->direct_submit_supp);
+}
+CONFIGFS_ATTR_RO(target_fabric_wwn_, direct_submit_supported);
+
 static struct configfs_attribute *target_fabric_wwn_param_attrs[] = {
 	&target_fabric_wwn_attr_cmd_completion_affinity,
+	&target_fabric_wwn_attr_default_submit_type,
+	&target_fabric_wwn_attr_direct_submit_supported,
 	NULL,
 };