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Commit 3cca6dc1 authored by Jens Axboe's avatar Jens Axboe
Browse files

block: add API for delaying work/request_fn a little bit 



Currently we use plugging for that, but as plugging is going away,
we need an alternative mechanism.

Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
parent 53f22956

block/blk-core.c

+29 −0
Original line number Diff line number Diff line
@@ -197,6 +197,32 @@ void blk_dump_rq_flags(struct request *rq, char *msg) 
}

EXPORT_SYMBOL(blk_dump_rq_flags);



static void blk_delay_work(struct work_struct *work)

{

	struct request_queue *q;



	q = container_of(work, struct request_queue, delay_work.work);

	spin_lock_irq(q->queue_lock);

	q->request_fn(q);

	spin_unlock_irq(q->queue_lock);

}



/**

 * blk_delay_queue - restart queueing after defined interval

 * @q:		The &struct request_queue in question

 * @msecs:	Delay in msecs

 *

 * Description:

 *   Sometimes queueing needs to be postponed for a little while, to allow

 *   resources to come back. This function will make sure that queueing is

 *   restarted around the specified time.

 */

void blk_delay_queue(struct request_queue *q, unsigned long msecs)

{

	schedule_delayed_work(&q->delay_work, msecs_to_jiffies(msecs));

}

EXPORT_SYMBOL(blk_delay_queue);



/*

 * "plug" the device if there are no outstanding requests: this will

 * force the transfer to start only after we have put all the requests
@@ -363,6 +389,7 @@ EXPORT_SYMBOL(blk_start_queue); 
void blk_stop_queue(struct request_queue *q)

{

	blk_remove_plug(q);

	cancel_delayed_work(&q->delay_work);

	queue_flag_set(QUEUE_FLAG_STOPPED, q);

}

EXPORT_SYMBOL(blk_stop_queue);
@@ -387,6 +414,7 @@ void blk_sync_queue(struct request_queue *q) 
	del_timer_sync(&q->timeout);

	cancel_work_sync(&q->unplug_work);

	throtl_shutdown_timer_wq(q);

	cancel_delayed_work_sync(&q->delay_work);

}

EXPORT_SYMBOL(blk_sync_queue);
@@ -534,6 +562,7 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) 
	INIT_LIST_HEAD(&q->flush_queue[1]);

	INIT_LIST_HEAD(&q->flush_data_in_flight);

	INIT_WORK(&q->unplug_work, blk_unplug_work);

	INIT_DELAYED_WORK(&q->delay_work, blk_delay_work);



	kobject_init(&q->kobj, &blk_queue_ktype);

include/linux/blkdev.h

+6 −0
Original line number Diff line number Diff line
@@ -300,6 +300,11 @@ struct request_queue 
	unsigned long		unplug_delay;	/* After this many jiffies */

	struct work_struct	unplug_work;



	/*

	 * Delayed queue handling

	 */

	struct delayed_work	delay_work;



	struct backing_dev_info	backing_dev_info;



	/*
@@ -677,6 +682,7 @@ extern int blk_insert_cloned_request(struct request_queue *q, 
extern void blk_plug_device(struct request_queue *);

extern void blk_plug_device_unlocked(struct request_queue *);

extern int blk_remove_plug(struct request_queue *);

extern void blk_delay_queue(struct request_queue *, unsigned long);

extern void blk_recount_segments(struct request_queue *, struct bio *);

extern int scsi_cmd_ioctl(struct request_queue *, struct gendisk *, fmode_t,

			  unsigned int, void __user *);