From dc72ef4ae35c2016fb594bcc85ce871376682174 Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@suse.de>
Date: Thu, 20 Jul 2006 14:54:05 +0200
Subject: [PATCH] [PATCH] Add blk_start_queueing() helper
CFQ implements this on its own now, but it's really block layer
knowledge. Tells a device queue to start dispatching requests to
the driver, taking care to unplug if needed. Also fixes the issue
where as/cfq will invoke a stopped queue, which we really don't
want.
Signed-off-by: Jens Axboe <axboe@suse.de>
---
block/as-iosched.c | 3 +--
block/cfq-iosched.c | 22 ++++------------------
block/ll_rw_blk.c | 25 ++++++++++++++++++++-----
include/linux/blkdev.h | 1 +
4 files changed, 26 insertions(+), 25 deletions(-)
diff --git a/block/as-iosched.c b/block/as-iosched.c
index f6dc95489316..bc13dc0b29be 100644
--- a/block/as-iosched.c
+++ b/block/as-iosched.c
@@ -1280,8 +1280,7 @@ static void as_work_handler(void *data)
unsigned long flags;
spin_lock_irqsave(q->queue_lock, flags);
- if (!as_queue_empty(q))
- q->request_fn(q);
+ blk_start_queueing(q);
spin_unlock_irqrestore(q->queue_lock, flags);
}
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 6fb1613d44d7..9f684cc66bd1 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1552,19 +1552,6 @@ static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
__cfq_set_active_queue(cfqd, cfqq);
}
-/*
- * should really be a ll_rw_blk.c helper
- */
-static void cfq_start_queueing(struct cfq_data *cfqd, struct cfq_queue *cfqq)
-{
- request_queue_t *q = cfqd->queue;
-
- if (!blk_queue_plugged(q))
- q->request_fn(q);
- else
- __generic_unplug_device(q);
-}
-
/*
* Called when a new fs request (rq) is added (to cfqq). Check if there's
* something we should do about it
@@ -1593,7 +1580,7 @@ cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
if (cic == cfqd->active_cic &&
del_timer(&cfqd->idle_slice_timer)) {
cfq_slice_expired(cfqd, 0);
- cfq_start_queueing(cfqd, cfqq);
+ blk_start_queueing(cfqd->queue);
}
return;
}
@@ -1614,7 +1601,7 @@ cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
if (cfq_cfqq_wait_request(cfqq)) {
cfq_mark_cfqq_must_dispatch(cfqq);
del_timer(&cfqd->idle_slice_timer);
- cfq_start_queueing(cfqd, cfqq);
+ blk_start_queueing(cfqd->queue);
}
} else if (cfq_should_preempt(cfqd, cfqq, rq)) {
/*
@@ -1624,7 +1611,7 @@ cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
*/
cfq_preempt_queue(cfqd, cfqq);
cfq_mark_cfqq_must_dispatch(cfqq);
- cfq_start_queueing(cfqd, cfqq);
+ blk_start_queueing(cfqd->queue);
}
}
@@ -1832,8 +1819,7 @@ static void cfq_kick_queue(void *data)
unsigned long flags;
spin_lock_irqsave(q->queue_lock, flags);
- blk_remove_plug(q);
- q->request_fn(q);
+ blk_start_queueing(q);
spin_unlock_irqrestore(q->queue_lock, flags);
}
diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index c6dfa889206c..346be9ae31f6 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -2266,6 +2266,25 @@ struct request *blk_get_request(request_queue_t *q, int rw, gfp_t gfp_mask)
}
EXPORT_SYMBOL(blk_get_request);
+/**
+ * blk_start_queueing - initiate dispatch of requests to device
+ * @q: request queue to kick into gear
+ *
+ * This is basically a helper to remove the need to know whether a queue
+ * is plugged or not if someone just wants to initiate dispatch of requests
+ * for this queue.
+ *
+ * The queue lock must be held with interrupts disabled.
+ */
+void blk_start_queueing(request_queue_t *q)
+{
+ if (!blk_queue_plugged(q))
+ q->request_fn(q);
+ else
+ __generic_unplug_device(q);
+}
+EXPORT_SYMBOL(blk_start_queueing);
+
/**
* blk_requeue_request - put a request back on queue
* @q: request queue where request should be inserted
@@ -2333,11 +2352,7 @@ void blk_insert_request(request_queue_t *q, struct request *rq,
drive_stat_acct(rq, rq->nr_sectors, 1);
__elv_add_request(q, rq, where, 0);
-
- if (blk_queue_plugged(q))
- __generic_unplug_device(q);
- else
- q->request_fn(q);
+ blk_start_queueing(q);
spin_unlock_irqrestore(q->queue_lock, flags);
}
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 6609371c303e..5d8e288db163 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -635,6 +635,7 @@ extern void blk_stop_queue(request_queue_t *q);
extern void blk_sync_queue(struct request_queue *q);
extern void __blk_stop_queue(request_queue_t *q);
extern void blk_run_queue(request_queue_t *);
+extern void blk_start_queueing(request_queue_t *);
extern void blk_queue_activity_fn(request_queue_t *, activity_fn *, void *);
extern int blk_rq_map_user(request_queue_t *, struct request *, void __user *, unsigned int);
extern int blk_rq_unmap_user(struct bio *, unsigned int);
--
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