block: add a blk_plug_device_unlocked() that grabs the queue lock

blk_plug_device() must be called with the queue lock held, so callers
often just grab and release the lock for that purpose. Add a helper
that does just that.

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

2 files changed, 19 insertions, 0 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index fef79ccb2a11..4889eb86a39e 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -212,6 +212,24 @@ void blk_plug_device(struct request_queue *q)
 }
 EXPORT_SYMBOL(blk_plug_device);
 
+/**
+ * blk_plug_device_unlocked - plug a device without queue lock held
+ * @q:    The &struct request_queue to plug
+ *
+ * Description:
+ *   Like @blk_plug_device(), but grabs the queue lock and disables
+ *   interrupts.
+ **/
+void blk_plug_device_unlocked(struct request_queue *q)
+{
+        unsigned long flags;
+
+        spin_lock_irqsave(q->queue_lock, flags);
+        blk_plug_device(q);
+        spin_unlock_irqrestore(q->queue_lock, flags);
+}
+EXPORT_SYMBOL(blk_plug_device_unlocked);
+
 /*
  * remove the queue from the plugged list, if present. called with
  * queue lock held and interrupts disabled.
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 88d68081a0f1..e61f22be4d0e 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -655,6 +655,7 @@ extern struct request *blk_get_request(struct request_queue *, int, gfp_t);
 extern void blk_insert_request(struct request_queue *, struct request *, int, void *);
 extern void blk_requeue_request(struct request_queue *, struct request *);
 extern void blk_plug_device(struct request_queue *);
+extern void blk_plug_device_unlocked(struct request_queue *);
 extern int blk_remove_plug(struct request_queue *);
 extern void blk_recount_segments(struct request_queue *, struct bio *);
 extern int scsi_cmd_ioctl(struct file *, struct request_queue *,