From: Zheng Liu Subject: Re: [RFC][PATCH 2/8 v2] ext4: add operations on extent status tree Date: Mon, 24 Sep 2012 11:35:09 +0800 Message-ID: <20120924033509.GB6196@gmail.com> References: <1345615545-26133-1-git-send-email-wenqing.lz@taobao.com> <1345615545-26133-3-git-send-email-wenqing.lz@taobao.com> <20120919184114.GC28470@thunk.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, Lukas Czerner , Yongqiang Yang , Allison Henderson , Zheng Liu To: Theodore Ts'o Return-path: Received: from mail-pb0-f46.google.com ([209.85.160.46]:60104 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754918Ab2IXDYf (ORCPT ); Sun, 23 Sep 2012 23:24:35 -0400 Content-Disposition: inline In-Reply-To: <20120919184114.GC28470@thunk.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Wed, Sep 19, 2012 at 02:41:14PM -0400, Theodore Ts'o wrote: > On Wed, Aug 22, 2012 at 02:05:39PM +0800, Zheng Liu wrote: > > + * Extents status encompass delayed extents and extent locks > > I've looked over this patch set, and as near as I can tell, we aren't > (yet) using the extents status structure to do extent-level locking. > I could imagine using that in the future so we aren't using i_data_sem > to lock out the entire tree, so block allocations could happen in > parallel, but that's not here yet. > > Is there something I'm missing, or was something else meant by "extent > locks" here? Hi Ted, In my plan, the first step for extent status tree is only to record delay extent in memory. It can simplify the implementation of fiemap and bigalloc, and introduce lseek SEEK_DATA/SEEK_HOLE support. That is all I want to finish in first step. I am very glad to see that these patches has been applied into dev branch even though it still has some problems. I will look at these problem ASAP. Indeed, in this patch set, extent-level locking is still not used because that is my next step in my plan [1]. I will try to use it after these patches are fully tested and applied. Thanks. 1. http://www.spinics.net/lists/linux-fsdevel/msg56291.html Regards, Zheng