target: Core cleanups from AGrover (round 1)

This patch contains the squashed version of a number of cleanups and
minor fixes from Andy's initial series (round 1) for target core this
past spring.  The condensed log looks like:

target: use errno values instead of returning -1 for everything
target: Rename transport_calc_sg_num to transport_init_task_sg
target: Fix leak in error path in transport_init_task_sg
target/pscsi: Remove pscsi_get_sh() usage
target: Make two runtime checks into WARN_ONs
target: Remove hba queue depth and convert to spin_lock_irq usage
target: dev->dev_status_queue_obj is unused
target: Make struct se_queue_req.cmd type struct se_cmd *
target: Remove __transport_get_qr_from_queue()
target: Rename se_dev->g_se_dev_list to se_dev_node
target: Remove struct se_global
target: Simplify scsi mib index table code
target: Make dev_queue_obj a member of se_device instead of a pointer
target: remove extraneous returns at end of void functions
target: Ensure transport_dump_vpd_ident_type returns null-terminated str
target: Function pointers don't need to use '&' to be assigned
target: Fix comment in __transport_execute_tasks()
target: Misc style cleanups
target: rename struct pr_reservation_template to pr_reservation
target: Remove #defines that just perform indirection
target: Inline transport_get_task_from_execute_queue()
target: Minor header comment fixes

Signed-off-by: Andy Grover <agrover@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/loopback/tcm_loop.c

@@ -118,7 +118,7 @@ static struct se_cmd *tcm_loop_allocate_core_cmd(
 	 * Signal BIDI usage with T_TASK(cmd)->t_tasks_bidi
 	 */
 	if (scsi_bidi_cmnd(sc))
-		T_TASK(se_cmd)->t_tasks_bidi = 1;
+		se_cmd->t_task->t_tasks_bidi = 1;
 	/*
 	 * Locate the struct se_lun pointer and attach it to struct se_cmd
 	 */
@@ -176,7 +176,7 @@ static int tcm_loop_new_cmd_map(struct se_cmd *se_cmd)
 		 * For BIDI commands, pass in the extra READ buffer
 		 * to transport_generic_map_mem_to_cmd() below..
 		 */
-		if (T_TASK(se_cmd)->t_tasks_bidi) {
+		if (se_cmd->t_task->t_tasks_bidi) {
 			struct scsi_data_buffer *sdb = scsi_in(sc);
 
 			mem_bidi_ptr = (void *)sdb->table.sgl;
@@ -1402,9 +1402,9 @@ static int tcm_loop_register_configfs(void)
 	 * Register the top level struct config_item_type with TCM core
 	 */
 	fabric = target_fabric_configfs_init(THIS_MODULE, "loopback");
-	if (!fabric) {
+	if (IS_ERR(fabric)) {
 		printk(KERN_ERR "tcm_loop_register_configfs() failed!\n");
-		return -1;
+		return PTR_ERR(fabric);
 	}
 	/*
 	 * Setup the fabric API of function pointers used by target_core_mod