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Subject[PATCH 01/10] block: add API for delaying work/request_fn a little bit
Date
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>
---
block/blk-core.c | 29 +++++++++++++++++++++++++++++
include/linux/blkdev.h | 6 ++++++
2 files changed, 35 insertions(+), 0 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 2f4002f..960f12c 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -207,6 +207,32 @@ 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
@@ -373,6 +399,7 @@ 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);
@@ -397,6 +424,7 @@ 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);

@@ -542,6 +570,7 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
INIT_LIST_HEAD(&q->timeout_list);
INIT_LIST_HEAD(&q->pending_flushes);
INIT_WORK(&q->unplug_work, blk_unplug_work);
+ INIT_DELAYED_WORK(&q->delay_work, blk_delay_work);

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

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 4d18ff3..b4812f9 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -294,6 +294,11 @@ 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;

/*
@@ -670,6 +675,7 @@ 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 *);
--
1.7.3.2.146.gca209


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