block: add blk_start_queue_async()

We currently only have an inline/sync helper to restart a stopped
queue. If drivers need an async version, they have to roll their
own. Add a generic helper instead.

Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/block/blk-core.c b/block/blk-core.c
index c487b94..33e2f62 100644 (file)
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -207,6 +207,22 @@ void blk_delay_queue(struct request_queue *q, unsigned long msecs)
 EXPORT_SYMBOL(blk_delay_queue);
 
 /**
+ * blk_start_queue_async - asynchronously restart a previously stopped queue
+ * @q:    The &struct request_queue in question
+ *
+ * Description:
+ *   blk_start_queue_async() will clear the stop flag on the queue, and
+ *   ensure that the request_fn for the queue is run from an async
+ *   context.
+ **/
+void blk_start_queue_async(struct request_queue *q)
+{
+       queue_flag_clear(QUEUE_FLAG_STOPPED, q);
+       blk_run_queue_async(q);
+}
+EXPORT_SYMBOL(blk_start_queue_async);
+
+/**
  * blk_start_queue - restart a previously stopped queue
  * @q:    The &struct request_queue in question
  *

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 0169ba2..c70e358 100644 (file)
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -797,6 +797,7 @@ extern int sg_scsi_ioctl(struct request_queue *, struct gendisk *, fmode_t,
 extern int blk_queue_enter(struct request_queue *q, gfp_t gfp);
 extern void blk_queue_exit(struct request_queue *q);
 extern void blk_start_queue(struct request_queue *q);
+extern void blk_start_queue_async(struct request_queue *q);
 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);