WorkStruct: Separate delayable and non-delayable events.

Separate delayable work items from non-delayable work items be splitting them
into a separate structure (delayed_work), which incorporates a work_struct and
the timer_list removed from work_struct.

The work_struct struct is huge, and this limits it's usefulness.  On a 64-bit
architecture it's nearly 100 bytes in size.  This reduces that by half for the
non-delayable type of event.

Signed-Off-By: David Howells <dhowells@redhat.com>
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 915a55a..0bb4b4d 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -937,12 +937,9 @@
 	if (ap->pflags & ATA_PFLAG_FLUSH_PORT_TASK)
 		return;
 
-	PREPARE_WORK(&ap->port_task, fn, data);
+	PREPARE_DELAYED_WORK(&ap->port_task, fn, data);
 
-	if (!delay)
-		rc = queue_work(ata_wq, &ap->port_task);
-	else
-		rc = queue_delayed_work(ata_wq, &ap->port_task, delay);
+	rc = queue_delayed_work(ata_wq, &ap->port_task, delay);
 
 	/* rc == 0 means that another user is using port task */
 	WARN_ON(rc == 0);
@@ -5320,8 +5317,8 @@
 	ap->msg_enable = ATA_MSG_DRV | ATA_MSG_ERR | ATA_MSG_WARN;
 #endif
 
-	INIT_WORK(&ap->port_task, NULL, NULL);
-	INIT_WORK(&ap->hotplug_task, ata_scsi_hotplug, ap);
+	INIT_DELAYED_WORK(&ap->port_task, NULL, NULL);
+	INIT_DELAYED_WORK(&ap->hotplug_task, ata_scsi_hotplug, ap);
 	INIT_WORK(&ap->scsi_rescan_task, ata_scsi_dev_rescan, ap);
 	INIT_LIST_HEAD(&ap->eh_done_q);
 	init_waitqueue_head(&ap->eh_wait_q);