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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: Jens Axboe <jaxboe@fusionio.com>
This commit is contained in:
Jens Axboe 2011-03-02 11:08:00 -05:00
parent 53f22956ef
commit 3cca6dc1c8
2 changed files with 35 additions and 0 deletions
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29
block/blk-core.c
View File

@ -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);

6
include/linux/blkdev.h
View File

@ -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 *);