[PATCH 3/3] block: Polling completion performance optimization

[Keith Busch]

When a request completion is polled, the completion task wakes itself
up. This is unnecessary, as the task can just set itself back to
running.

Signed-off-by: Keith Busch <keith.busch at intel.com>
---
 fs/block_dev.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 4a181fcb5175..ce67ffe73430 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -181,7 +181,10 @@ static void blkdev_bio_end_io_simple(struct bio *bio)
 	struct task_struct *waiter = bio->bi_private;
 
 	WRITE_ONCE(bio->bi_private, NULL);
-	wake_up_process(waiter);
+	if (current != waiter)
+		wake_up_process(waiter);
+	else
+		__set_current_state(TASK_RUNNING);
 }
 
 static ssize_t
-- 
2.13.6