[PATCH] block: add blk_run_queue_async

Christoph Hellwig
2011-04-18T09:26:55Z

Instead of overloading __blk_run_queue to force an offload to kblockd
add a new blk_run_queue_async helper to do it explicitly. I've kept
the blk_queue_stopped check for now, but I suspect it's not needed
as the check we do when the workqueue items runs should be enough.

Signed-off-by: Christoph Hellwig <hch@lst.de>

Index: linux-2.6/block/blk-core.c
===================================================================
--- linux-2.6.orig/block/blk-core.c 2011-04-18 10:48:11.010100413 +0200
+++ linux-2.6/block/blk-core.c 2011-04-18 10:57:56.340262741 +0200
@@ -204,7 +204,7 @@ static void blk_delay_work(struct work_s

q = container_of(work, struct request_queue, delay_work.work);
spin_lock_irq(q->queue_lock);
- __blk_run_queue(q, false);
+ __blk_run_queue(q);
spin_unlock_irq(q->queue_lock);
}

@@ -238,7 +238,7 @@ void blk_start_queue(struct request_queu
WARN_ON(!irqs_disabled());

queue_flag_clear(QUEUE_FLAG_STOPPED, q);
- __blk_run_queue(q, false);
+ __blk_run_queue(q);
}
EXPORT_SYMBOL(blk_start_queue);

@@ -295,11 +295,9 @@ EXPORT_SYMBOL(blk_sync_queue);
*
* Description:
* See @blk_run_queue. This variant must be called with the queue lock
- * held and interrupts disabled. If force_kblockd is true, then it is
- * safe to call this without holding the queue lock.
- *
+ * held and interrupts disabled.
*/
-void __blk_run_queue(struct request_queue *q, bool force_kblockd)
+void __blk_run_queue(struct request_queue *q)
{
if (unlikely(blk_queue_stopped(q)))
return;
@@ -308,7 +306,7 @@ void __blk_run_queue(struct request_queu
* Only recurse once to avoid overrunning the stack, let the unplug
* handling reinvoke the handler shortly if we already got there.
*/
- if (!force_kblockd && !queue_flag_test_and_set(QUEUE_FLAG_REENTER, q)) {
+ if (!queue_flag_test_and_set(QUEUE_FLAG_REENTER, q)) {
q->request_fn(q);
queue_flag_clear(QUEUE_FLAG_REENTER, q);
} else
@@ -317,6 +315,20 @@ void __blk_run_queue(struct request_queu
EXPORT_SYMBOL(__blk_run_queue);

/**
+ * blk_run_queue_async - run a single device queue in workqueue context
+ * @q: The queue to run
+ *
+ * Description:
+ * Tells kblockd to perform the equivalent of @blk_run_queue on behalf
+ * of us.
+ */
+void blk_run_queue_async(struct request_queue *q)
+{
+ if (likely(!blk_queue_stopped(q)))
+ queue_delayed_work(kblockd_workqueue, &q->delay_work, 0);
+}
+
+/**
* blk_run_queue - run a single device queue
* @q: The queue to run
*
@@ -329,7 +341,7 @@ void blk_run_queue(struct request_queue
unsigned long flags;

spin_lock_irqsave(q->queue_lock, flags);
- __blk_run_queue(q, false);
+ __blk_run_queue(q);
spin_unlock_irqrestore(q->queue_lock, flags);
}
EXPORT_SYMBOL(blk_run_queue);
@@ -978,7 +990,7 @@ void blk_insert_request(struct request_q
blk_queue_end_tag(q, rq);

add_acct_request(q, rq, where);
- __blk_run_queue(q, false);
+ __blk_run_queue(q);
spin_unlock_irqrestore(q->queue_lock, flags);
}
EXPORT_SYMBOL(blk_insert_request);
@@ -1322,7 +1334,7 @@ get_rq:
} else {
spin_lock_irq(q->queue_lock);
add_acct_request(q, req, where);
- __blk_run_queue(q, false);
+ __blk_run_queue(q);
out_unlock:
spin_unlock_irq(q->queue_lock);
}
@@ -2683,9 +2695,9 @@ static void queue_unplugged(struct reque
*/
if (from_schedule) {
spin_unlock(q->queue_lock);
- __blk_run_queue(q, true);
+ blk_run_queue_async(q);
} else {
- __blk_run_queue(q, false);
+ __blk_run_queue(q);
spin_unlock(q->queue_lock);
}

Index: linux-2.6/block/blk-exec.c
===================================================================
--- linux-2.6.orig/block/blk-exec.c 2011-04-18 10:48:11.033433621 +0200
+++ linux-2.6/block/blk-exec.c 2011-04-18 10:50:12.346109746 +0200
@@ -55,7 +55,7 @@ void blk_execute_rq_nowait(struct reques
WARN_ON(irqs_disabled());
spin_lock_irq(q->queue_lock);
__elv_add_request(q, rq, where);
- __blk_run_queue(q, false);
+ __blk_run_queue(q);
/* the queue is stopped so it won't be plugged+unplugged */
if (rq->cmd_type == REQ_TYPE_PM_RESUME)
q->request_fn(q);
Index: linux-2.6/block/blk-flush.c
===================================================================
--- linux-2.6.orig/block/blk-flush.c 2011-04-18 10:48:11.056766826 +0200
+++ linux-2.6/block/blk-flush.c 2011-04-18 10:57:45.336989017 +0200
@@ -218,7 +218,7 @@ static void flush_end_io(struct request
* request_fn may confuse the driver. Always use kblockd.
*/
if (queued)
- __blk_run_queue(q, true);
+ blk_run_queue_async(q);
}

/**
@@ -274,7 +274,7 @@ static void flush_data_end_io(struct req
* the comment in flush_end_io().
*/
if (blk_flush_complete_seq(rq, REQ_FSEQ_DATA, error))
- __blk_run_queue(q, true);
+ blk_run_queue_async(q);
}

/**
Index: linux-2.6/block/cfq-iosched.c
===================================================================
--- linux-2.6.orig/block/cfq-iosched.c 2011-04-18 10:48:11.080100033 +0200
+++ linux-2.6/block/cfq-iosched.c 2011-04-18 10:51:08.599138332 +0200
@@ -3368,7 +3368,7 @@ cfq_rq_enqueued(struct cfq_data *cfqd, s
cfqd->busy_queues > 1) {
cfq_del_timer(cfqd, cfqq);
cfq_clear_cfqq_wait_request(cfqq);
- __blk_run_queue(cfqd->queue, false);
+ __blk_run_queue(cfqd->queue);
} else {
cfq_blkiocg_update_idle_time_stats(
&cfqq->cfqg->blkg);
@@ -3383,7 +3383,7 @@ cfq_rq_enqueued(struct cfq_data *cfqd, s
* this new queue is RT and the current one is BE
*/
cfq_preempt_queue(cfqd, cfqq);
- __blk_run_queue(cfqd->queue, false);
+ __blk_run_queue(cfqd->queue);
}
}

@@ -3743,7 +3743,7 @@ static void cfq_kick_queue(struct work_s
struct request_queue *q = cfqd->queue;

spin_lock_irq(q->queue_lock);
- __blk_run_queue(cfqd->queue, false);
+ __blk_run_queue(cfqd->queue);
spin_unlock_irq(q->queue_lock);
}

Index: linux-2.6/block/elevator.c
===================================================================
--- linux-2.6.orig/block/elevator.c 2011-04-18 10:48:11.103433241 +0200
+++ linux-2.6/block/elevator.c 2011-04-18 10:51:24.849050298 +0200
@@ -642,7 +642,7 @@ void elv_quiesce_start(struct request_qu
*/
elv_drain_elevator(q);
while (q->rq.elvpriv) {
- __blk_run_queue(q, false);
+ __blk_run_queue(q);
spin_unlock_irq(q->queue_lock);
msleep(10);
spin_lock_irq(q->queue_lock);
@@ -695,7 +695,7 @@ void __elv_add_request(struct request_qu
* with anything. There's no point in delaying queue
* processing.
*/
- __blk_run_queue(q, false);
+ __blk_run_queue(q);
break;

case ELEVATOR_INSERT_SORT_MERGE:
Index: linux-2.6/drivers/scsi/scsi_lib.c
===================================================================
--- linux-2.6.orig/drivers/scsi/scsi_lib.c 2011-04-18 10:48:11.126766448 +0200
+++ linux-2.6/drivers/scsi/scsi_lib.c 2011-04-18 10:51:31.449014543 +0200
@@ -443,7 +443,7 @@ static void scsi_run_queue(struct reques
&sdev->request_queue->queue_flags);
if (flagset)
queue_flag_set(QUEUE_FLAG_REENTER, sdev->request_queue);
- __blk_run_queue(sdev->request_queue, false);
+ __blk_run_queue(sdev->request_queue);
if (flagset)
queue_flag_clear(QUEUE_FLAG_REENTER, sdev->request_queue);
spin_unlock(sdev->request_queue->queue_lock);
Index: linux-2.6/drivers/scsi/scsi_transport_fc.c
===================================================================
--- linux-2.6.orig/drivers/scsi/scsi_transport_fc.c 2011-04-18 10:48:11.150099654 +0200
+++ linux-2.6/drivers/scsi/scsi_transport_fc.c 2011-04-18 10:53:09.508483308 +0200
@@ -3829,7 +3829,7 @@ fc_bsg_goose_queue(struct fc_rport *rpor
!test_bit(QUEUE_FLAG_REENTER, &rport->rqst_q->queue_flags);
if (flagset)
queue_flag_set(QUEUE_FLAG_REENTER, rport->rqst_q);
- __blk_run_queue(rport->rqst_q, false);
+ __blk_run_queue(rport->rqst_q);
if (flagset)
queue_flag_clear(QUEUE_FLAG_REENTER, rport->rqst_q);
spin_unlock_irqrestore(rport->rqst_q->queue_lock, flags);
Index: linux-2.6/block/blk.h
===================================================================
--- linux-2.6.orig/block/blk.h 2011-04-18 10:53:39.001656864 +0200
+++ linux-2.6/block/blk.h 2011-04-18 11:00:28.066107438 +0200
@@ -22,6 +22,7 @@ void blk_rq_timed_out_timer(unsigned lon
void blk_delete_timer(struct request *);
void blk_add_timer(struct request *);
void __generic_unplug_device(struct request_queue *);
+void blk_run_queue_async(struct request_queue *q);

/*
* Internal atomic flags for request handling
Index: linux-2.6/include/linux/blkdev.h
===================================================================
--- linux-2.6.orig/include/linux/blkdev.h 2011-04-18 10:48:11.170099546 +0200
+++ linux-2.6/include/linux/blkdev.h 2011-04-18 10:58:41.003354113 +0200
@@ -697,7 +697,7 @@ extern void blk_start_queue(struct reque
extern void blk_stop_queue(struct request_queue *q);
extern void blk_sync_queue(struct request_queue *q);
extern void __blk_stop_queue(struct request_queue *q);
-extern void __blk_run_queue(struct request_queue *q, bool force_kblockd);
+extern void __blk_run_queue(struct request_queue *q);
extern void blk_run_queue(struct request_queue *);
extern int blk_rq_map_user(struct request_queue *, struct request *,
struct rq_map_data *, void __user *, unsigned long,