-/*
- * "plug" the device if there are no outstanding requests: this will
- * force the transfer to start only after we have put all the requests
- * on the list.
- *
- * This is called with interrupts off and no requests on the queue and
- * with the queue lock held.
- */
-void blk_plug_device(struct request_queue *q)
-{
- WARN_ON(!irqs_disabled());
-
- /*
- * don't plug a stopped queue, it must be paired with blk_start_queue()
- * which will restart the queueing
- */
- if (blk_queue_stopped(q))
- return;
-
- if (!queue_flag_test_and_set(QUEUE_FLAG_PLUGGED, q)) {
- mod_timer(&q->unplug_timer, jiffies + q->unplug_delay);
- trace_block_plug(q);
- }
-}
-EXPORT_SYMBOL(blk_plug_device);
-
-/**
- * blk_plug_device_unlocked - plug a device without queue lock held
- * @q: The &struct request_queue to plug
- *
- * Description:
- * Like @blk_plug_device(), but grabs the queue lock and disables
- * interrupts.
- **/
-void blk_plug_device_unlocked(struct request_queue *q)
-{
- unsigned long flags;
-
- spin_lock_irqsave(q->queue_lock, flags);
- blk_plug_device(q);
- spin_unlock_irqrestore(q->queue_lock, flags);
-}
-EXPORT_SYMBOL(blk_plug_device_unlocked);
-
-/*
- * remove the queue from the plugged list, if present. called with
- * queue lock held and interrupts disabled.
- */
-int blk_remove_plug(struct request_queue *q)
-{
- WARN_ON(!irqs_disabled());
-
- if (!queue_flag_test_and_clear(QUEUE_FLAG_PLUGGED, q))
- return 0;
-
- del_timer(&q->unplug_timer);
- return 1;
-}
-EXPORT_SYMBOL(blk_remove_plug);
-
-/*
- * remove the plug and let it rip..
- */
-void __generic_unplug_device(struct request_queue *q)
-{
- if (unlikely(blk_queue_stopped(q)))
- return;
- if (!blk_remove_plug(q) && !blk_queue_nonrot(q))
- return;
-
- q->request_fn(q);
-}
-
-/**
- * generic_unplug_device - fire a request queue
- * @q: The &struct request_queue in question
- *
- * Description:
- * Linux uses plugging to build bigger requests queues before letting
- * the device have at them. If a queue is plugged, the I/O scheduler
- * is still adding and merging requests on the queue. Once the queue
- * gets unplugged, the request_fn defined for the queue is invoked and
- * transfers started.
- **/
-void generic_unplug_device(struct request_queue *q)
-{
- if (blk_queue_plugged(q)) {
- spin_lock_irq(q->queue_lock);
- __generic_unplug_device(q);
- spin_unlock_irq(q->queue_lock);
- }
-}
-EXPORT_SYMBOL(generic_unplug_device);
-
-static void blk_backing_dev_unplug(struct backing_dev_info *bdi,
- struct page *page)
-{
- struct request_queue *q = bdi->unplug_io_data;
-
- blk_unplug(q);
-}
-
-void blk_unplug_work(struct work_struct *work)
-{
- struct request_queue *q =
- container_of(work, struct request_queue, unplug_work);
-
- trace_block_unplug_io(q);
- q->unplug_fn(q);
-}
-
-void blk_unplug_timeout(unsigned long data)
-{
- struct request_queue *q = (struct request_queue *)data;
-
- trace_block_unplug_timer(q);
- kblockd_schedule_work(q, &q->unplug_work);
-}
-
-void blk_unplug(struct request_queue *q)
-{
- /*
- * devices don't necessarily have an ->unplug_fn defined
- */
- if (q->unplug_fn) {
- trace_block_unplug_io(q);
- q->unplug_fn(q);
- }
-}
-EXPORT_SYMBOL(blk_unplug);
-