[PATCH 1/2] block: add a helper to cancel atomic queue limit updates

[Christoph Hellwig]

Drivers might have to perform complex actions to determine queue limits,
and those might fail.  Add a helper to cancel a queue limit update
that can be called in those cases.

Signed-off-by: Christoph Hellwig <hch at lst.de>
---
 include/linux/blkdev.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index f9b87c39cab047..39fedc8ef9c41f 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -892,6 +892,19 @@ int queue_limits_commit_update(struct request_queue *q,
 		struct queue_limits *lim);
 int queue_limits_set(struct request_queue *q, struct queue_limits *lim);
 
+/**
+ * queue_limits_cancel_update - cancel an atomic update of queue limits
+ * @q:		queue to update
+ *
+ * This functions cancels an atomic update of the queue limits started by
+ * queue_limits_start_update() and should be used when an error occurs after
+ * starting update.
+ */
+static inline void queue_limits_cancel_update(struct request_queue *q)
+{
+	mutex_lock(&q->limits_lock);
+}
+
 /*
  * Access functions for manipulating queue properties
  */
-- 
2.39.2