orangefs: return from orangefs_devreq_read quickly if possible

It is not necessary to take the lock and search through the request list if the list is empty. Signed-off-by: Martin Brandenburg <[email protected]> Signed-off-by: Mike Marshall <[email protected]>
kawasaki · Apr 26, 2017 · b7a57cc · b7a57cc
1 parent 9d286b0
commit b7a57cc
Showing 1 changed file with 4 additions and 0 deletions.
diff --git a/fs/orangefs/devorangefs-req.c b/fs/orangefs/devorangefs-req.c
@@ -180,6 +180,10 @@ static ssize_t orangefs_devreq_read(struct file *file,
 		return -EINVAL;
 	}
 
+	/* Check for an empty list before locking. */
+	if (list_empty(&orangefs_request_list))
+		return -EAGAIN;
+
 restart:
 	/* Get next op (if any) from top of list. */
 	spin_lock(&orangefs_request_list_lock);