From: Andrew Morton Subject: Re: [EXT4 set 4][PATCH 2/5] i_version: Add hi 32 bit inode version on ext4 on-disk inode Date: Tue, 10 Jul 2007 16:30:47 -0700 Message-ID: <20070710163047.1aba94f9.akpm@linux-foundation.org> References: <1183275436.4010.127.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: 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: In-Reply-To: <1183275436.4010.127.camel@localhost.localdomain> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Sun, 01 Jul 2007 03:37:16 -0400 Mingming Cao wrote: > This patch adds a 32-bit i_version_hi field to ext4_inode, which can be used for 64-bit inode versions. This field will store the higher 32 bits of the version, while Jean Noel's patch has added support to store the lower 32-bits in osd1.linux1.l_i_version. Please wordwrap this changelog entry to less than 80 columns. Well, less than 258, anyway ;) > Signed-off-by: Mingming Cao > Signed-off-by: Andreas Dilger > Signed-off-by: Kalpak Shah > --- > Index: linux-2.6.21/include/linux/ext4_fs.h > =================================================================== > --- linux-2.6.21.orig/include/linux/ext4_fs.h > +++ linux-2.6.21/include/linux/ext4_fs.h > @@ -342,6 +342,7 @@ struct ext4_inode { > __le32 i_atime_extra; /* extra Access time (nsec << 2 | epoch) */ > __le32 i_crtime; /* File Creation time */ > __le32 i_crtime_extra; /* extra FileCreationtime (nsec << 2 | epoch) */ > + __le32 i_version_hi; /* high 32 bits for 64-bit version */ > }; Aren't there forward- backward-compatibility issues here? How does the filesystem driver work out whether this field is present and valid? The changelog should describe this design issue.