[v6,1/4] block: add blk_mq_is_queue_frozen()

Commit Message

Sergei Shtepa March 3, 2021, 12:30 p.m. UTC

blk_mq_is_queue_frozen() allow to assert that the queue is frozen.

Signed-off-by: Sergei Shtepa <[e-mail]>
---
 block/blk-mq.c         | 12 ++++++++++++
 include/linux/blk-mq.h |  1 +
 2 files changed, 13 insertions(+)

Comments

Christoph Hellwig March 9, 2021, 5:19 p.m. UTC | #1

On Wed, Mar 03, 2021 at 03:30:15PM +0300, Sergei Shtepa wrote:
> +bool blk_mq_is_queue_frozen(struct request_queue *q)
> +{
> +	bool ret;
> +
> +	mutex_lock(&q->mq_freeze_lock);
> +	ret = percpu_ref_is_dying(&q->q_usage_counter) && percpu_ref_is_zero(&q->q_usage_counter);

Please avoid the overly long line.

Also maybe frozen is a better name for the variable currently called
ret?

Patch

diff --git a/block/blk-mq.c b/block/blk-mq.c
index d4d7c1caa439..d5e7122789fc 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -161,6 +161,18 @@  int blk_mq_freeze_queue_wait_timeout(struct request_queue *q,
 }
 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout);
 
+bool blk_mq_is_queue_frozen(struct request_queue *q)
+{
+	bool ret;
+
+	mutex_lock(&q->mq_freeze_lock);
+	ret = percpu_ref_is_dying(&q->q_usage_counter) && percpu_ref_is_zero(&q->q_usage_counter);
+	mutex_unlock(&q->mq_freeze_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(blk_mq_is_queue_frozen);
+
 /*
  * Guarantee no request is in use, so we can change any data structure of
  * the queue afterward.
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 2c473c9b8990..6f01971abf7b 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -533,6 +533,7 @@  void blk_freeze_queue_start(struct request_queue *q);
 void blk_mq_freeze_queue_wait(struct request_queue *q);
 int blk_mq_freeze_queue_wait_timeout(struct request_queue *q,
 				     unsigned long timeout);
+bool blk_mq_is_queue_frozen(struct request_queue *q);
 
 int blk_mq_map_queues(struct blk_mq_queue_map *qmap);
 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues);