target: Add device attribute to expose config_item_name for INQUIRY model

This patch changes LIO to use the configfs backend device name as the
model if you echo '1' to an individual device's emulate_model_alias attribute.
This is a valid operation only on devices with an export count of 0.

Signed-off-by: Tregaron Bayly <tbayly@bluehost.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 199b0ad..df14dce 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -75,6 +75,8 @@
 #define DA_MAX_WRITE_SAME_LEN			0
 /* Default max transfer length */
 #define DA_FABRIC_MAX_SECTORS			8192
+/* Use a model alias based on the configfs backend device name */
+#define DA_EMULATE_MODEL_ALIAS			0
 /* Emulation for Direct Page Out */
 #define DA_EMULATE_DPO				0
 /* Emulation for Forced Unit Access WRITEs */
@@ -591,6 +593,7 @@
 };
 
 struct se_dev_attrib {
+	int		emulate_model_alias;
 	int		emulate_dpo;
 	int		emulate_fua_write;
 	int		emulate_fua_read;