[Patch] pipe: use file_update_time() when hold i_mutex

[Amerigo Wang <amwang@redhat.com>]

file_update_time() should be called with i_mutex held,
move it before mutex_unlock().

Signed-off-by: WANG Cong <amwang@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Miklos Szeredi <mszeredi@suse.cz>

---
diff --git a/fs/pipe.c b/fs/pipe.c
index f7dd21a..724b035 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -602,13 +602,14 @@ redo2:
 		pipe->waiting_writers--;
 	}
 out:
+	if (ret > 0)
+		file_update_time(filp);
+
 	mutex_unlock(&inode->i_mutex);
 	if (do_wakeup) {
 		wake_up_interruptible_sync(&pipe->wait);
 		kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
 	}
-	if (ret > 0)
-		file_update_time(filp);
 	return ret;
 }