From: Andrew Morton Subject: Re: [EXT4 set 4][PATCH 1/5] i_version:64 bit inode version Date: Tue, 10 Jul 2007 23:35:29 -0700 Message-ID: <20070710233529.7d8bfe9a.akpm@linux-foundation.org> References: <1183275424.4010.126.camel@localhost.localdomain> <20070710163038.ceb2ae94.akpm@linux-foundation.org> <1184105380.3759.65.camel@localhost.localdomain> <20070710182237.e2f88bf3.akpm@linux-foundation.org> <18068.19667.942363.686858@notabene.brown> <1184119748.20193.37.camel@localhost.localdomain> <20070710221721.23c46edf.akpm@linux-foundation.org> <1184123930.20193.61.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Neil Brown , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-ext4@vger.kernel.org, nfsv4@linux-nfs.org To: cmm@us.ibm.com Return-path: Received: from smtp2.linux-foundation.org ([207.189.120.14]:37211 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751943AbXGKGft (ORCPT ); Wed, 11 Jul 2007 02:35:49 -0400 In-Reply-To: <1184123930.20193.61.camel@localhost.localdomain> Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Tue, 10 Jul 2007 23:18:50 -0400 Mingming Cao wrote: > On Tue, 2007-07-10 at 22:17 -0700, Andrew Morton wrote: > > On Tue, 10 Jul 2007 22:09:08 -0400 Mingming Cao wrote: > > > > > David Chinneer pointed that we need to journal the version number > > > updates together with the operations that causes the change of the inode > > > version number, in order to survive server crashes so clients won't see > > > the counter go backwards. > > > > > > So increment i_version in fs code is probably the place to ensure the > > > inode version changes are stored to disk. It's seems update the ext4 > > > inode version in every ext4_mark_inode_dirty() is the easiest way. > > > > That still makes us dependent upon _something_ changing the inode. For > > overwrites the only something is mtime. > > > > If we don't want to have a peculiar dependency upon s_time_gran=1e9 (and > > I don't think we do) then I guess we'll need new code in or around > > file_update_time() to do this. > > do you mean mark inode dirty all the times in file_update_time()? Not > sure about the overhead for ext3/4. > hm, I hadn't thought about it in any detail. Maybe something like --- a/fs/inode.c~a +++ a/fs/inode.c @@ -1238,6 +1238,11 @@ void file_update_time(struct file *file) sync_it = 1; } + if (IS_I_VERSION_64(inode)) { + inode_inc_iversion(inode); /* Takes i_lock on 32-bit */ + sync_it = 1; + } + if (sync_it) mark_inode_dirty_sync(inode); } _ ?