From: Andreas Dilger Subject: Re: [RFC] [patch 2/2] i_version update - ext4 part Date: Mon, 14 May 2007 14:31:48 -0600 Message-ID: <20070514203147.GA26257@schatzie.adilger.int> References: <1179140701.7733.4.camel@frecb002711.frec.bull.fr> <20070514202148.GE5286@schatzie.adilger.int> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-ext4@vger.kernel.org, Kalpak Shah To: Cordenner jean noel Return-path: Received: from mail.clusterfs.com ([206.168.112.78]:43484 "EHLO mail.clusterfs.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755759AbXENUbu (ORCPT ); Mon, 14 May 2007 16:31:50 -0400 Content-Disposition: inline In-Reply-To: <20070514202148.GE5286@schatzie.adilger.int> Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On May 14, 2007 14:21 -0600, Andreas Dilger wrote: > On May 14, 2007 13:05 +0200, Cordenner jean noel wrote: > > @@ -331,12 +331,13 @@ > > } osd2; /* OS dependent 2 */ > > __le16 i_extra_isize; > > __le16 i_pad1; > > + __le32 i_disk_version_hi; > > No, this is not correct. There are already several other fields here > (nanosecond ctime, mtime, atime, crtime (creation time)) so you need > to use the correct reserved field for this. > > __u16 i_extra_isize; > __u16 i_pad1; > __u32 i_ctime_extra; /* extra Change time (nsec << 2 | epoch) */ > __u32 i_mtime_extra; /* extra Modification time (nsec << 2 | epoch)*/ > __u32 i_atime_extra; /* extra Access time (nsec << 2 | epoch) */ > __u32 i_crtime; /* File creation time */ > __u32 i_crtime_extra; /* extra File creation time (nsec << 2 |epoch)*/ Sorry, I meant to add (before hitting send :-) that the field after i_crtime_extra is supposed to be "i_disk_version_hi". See the patch from Kalpak Shah "[RFC] 64-bit inode version" which also handles the case for expanding i_extra_isize to cover the needed extra fields if i_extra_isize is not large enough. That patch didn't include the 64-bit i_version_hi yet, because there wasn't yet agreement at that time if the iversion_hi should be allocated separately, but that was since decided. Without that patch, your patch will possibly corrupt the extended attributes by just overwriting i_disk_version_hi while ignoring the actual value of i_extra_isize. This would clobber the EA magic and result in loss of all EAs in that inode. Cheers, Andreas -- Andreas Dilger Principal Software Engineer Cluster File Systems, Inc.