make get_file() return its argument

simplifies a bunch of callers...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c
index da8876d..dce436e 100644
--- a/fs/autofs4/waitq.c
+++ b/fs/autofs4/waitq.c
@@ -175,8 +175,7 @@
 		return;
 	}
 
-	pipe = sbi->pipe;
-	get_file(pipe);
+	pipe = get_file(sbi->pipe);
 
 	mutex_unlock(&sbi->wq_mutex);