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Date: Thu, 26 Dec 2013 21:31:35 +0800
From: Ming Lei <tom.leiming@...il.com>
To: Jens Axboe <axboe@...nel.dk>, linux-kernel@...r.kernel.org
Cc: Christoph Hellwig <hch@...radead.org>,
Ming Lei <tom.leiming@...il.com>
Subject: [PATCH v1 2/5] block: blk-mq: support draining mq queue
blk_mq_drain_queue() is introduced so that we can drain
mq queue inside blk_cleanup_queue().
Also don't accept new requests any more if queue is marked
as dying.
Cc: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Ming Lei <tom.leiming@...il.com>
---
block/blk-core.c | 10 ++++++++--
block/blk-exec.c | 4 ++++
block/blk-mq.c | 43 +++++++++++++++++++++++++++----------------
block/blk-mq.h | 1 +
4 files changed, 40 insertions(+), 18 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index 5da8e90..accb7fc 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -38,6 +38,7 @@
#include "blk.h"
#include "blk-cgroup.h"
+#include "blk-mq.h"
EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap);
EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap);
@@ -497,8 +498,13 @@ void blk_cleanup_queue(struct request_queue *q)
* Drain all requests queued before DYING marking. Set DEAD flag to
* prevent that q->request_fn() gets invoked after draining finished.
*/
- spin_lock_irq(lock);
- __blk_drain_queue(q, true);
+ if (q->mq_ops) {
+ blk_mq_drain_queue(q);
+ spin_lock_irq(lock);
+ } else {
+ spin_lock_irq(lock);
+ __blk_drain_queue(q, true);
+ }
queue_flag_set(QUEUE_FLAG_DEAD, q);
spin_unlock_irq(lock);
diff --git a/block/blk-exec.c b/block/blk-exec.c
index c3edf9d..bbfc072 100644
--- a/block/blk-exec.c
+++ b/block/blk-exec.c
@@ -60,6 +60,10 @@ void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk,
rq->rq_disk = bd_disk;
rq->end_io = done;
+ /*
+ * don't check dying flag for MQ because the request won't
+ * be resued after dying flag is set
+ */
if (q->mq_ops) {
blk_mq_insert_request(q, rq, true);
return;
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 35ae189..38b7bde 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -105,10 +105,13 @@ static int blk_mq_queue_enter(struct request_queue *q)
spin_lock_irq(q->queue_lock);
ret = wait_event_interruptible_lock_irq(q->mq_freeze_wq,
- !blk_queue_bypass(q), *q->queue_lock);
+ !blk_queue_bypass(q) || blk_queue_dying(q),
+ *q->queue_lock);
/* inc usage with lock hold to avoid freeze_queue runs here */
- if (!ret)
+ if (!ret && !blk_queue_dying(q))
__percpu_counter_add(&q->mq_usage_counter, 1, 1000000);
+ else if (blk_queue_dying(q))
+ ret = -ENODEV;
spin_unlock_irq(q->queue_lock);
return ret;
@@ -119,6 +122,22 @@ static void blk_mq_queue_exit(struct request_queue *q)
__percpu_counter_add(&q->mq_usage_counter, -1, 1000000);
}
+static void __blk_mq_drain_queue(struct request_queue *q)
+{
+ while (true) {
+ s64 count;
+
+ spin_lock_irq(q->queue_lock);
+ count = percpu_counter_sum(&q->mq_usage_counter);
+ spin_unlock_irq(q->queue_lock);
+
+ if (count == 0)
+ break;
+ blk_mq_run_queues(q, false);
+ msleep(10);
+ }
+}
+
/*
* Guarantee no request is in use, so we can change any data structure of
* the queue afterward.
@@ -132,21 +151,13 @@ static void blk_mq_freeze_queue(struct request_queue *q)
queue_flag_set(QUEUE_FLAG_BYPASS, q);
spin_unlock_irq(q->queue_lock);
- if (!drain)
- return;
-
- while (true) {
- s64 count;
-
- spin_lock_irq(q->queue_lock);
- count = percpu_counter_sum(&q->mq_usage_counter);
- spin_unlock_irq(q->queue_lock);
+ if (drain)
+ __blk_mq_drain_queue(q);
+}
- if (count == 0)
- break;
- blk_mq_run_queues(q, false);
- msleep(10);
- }
+void blk_mq_drain_queue(struct request_queue *q)
+{
+ __blk_mq_drain_queue(q);
}
static void blk_mq_unfreeze_queue(struct request_queue *q)
diff --git a/block/blk-mq.h b/block/blk-mq.h
index 5761eed..35ff4f7 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -27,6 +27,7 @@ void blk_mq_complete_request(struct request *rq, int error);
void blk_mq_run_request(struct request *rq, bool run_queue, bool async);
void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async);
void blk_mq_init_flush(struct request_queue *q);
+void blk_mq_drain_queue(struct request_queue *q);
/*
* CPU hotplug helpers
--
1.7.9.5
--
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