From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ie0-f176.google.com ([209.85.223.176]:42501 "EHLO mail-ie0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755214Ab3I1Xfg (ORCPT ); Sat, 28 Sep 2013 19:35:36 -0400 Received: by mail-ie0-f176.google.com with SMTP id as1so6988444iec.21 for ; Sat, 28 Sep 2013 16:35:35 -0700 (PDT) MIME-Version: 1.0 From: Aastha Mehta Date: Sun, 29 Sep 2013 01:35:15 +0200 Message-ID: Subject: Questions regarding logging upon fsync in btrfs To: linux-btrfs Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-btrfs-owner@vger.kernel.org List-ID: Hi, I have few questions regarding logging triggered by calling fsync in BTRFS: 1. If I understand correctly, fsync will call to log entire inode in the log tree. Does this mean that the data extents are also logged into the log tree? Are they copied into the log tree, or just referenced? Are they copied into the subvolume's extent tree again upon replay? 2. During replay, when the extents are added into the extent allocation tree, do they acquire the physical extent number during replay? Does they physical extent allocated to the data in the log tree differ from that in the subvolume? 3. I see there is a mount option of notreelog available. After disabling tree logging, does fsync still lead to flushing of buffers to the disk directly? 4. Is it possible to selectively identify certain files in the log tree and flush them to disk directly, without waiting for the replay to do it? Thanks -- Aastha Mehta