From: Mingming Cao Subject: Re: [patch 0/2] i_version update Date: Wed, 30 May 2007 16:32:57 -0700 Message-ID: <1180567978.3794.28.camel@dyn9047017103.beaverton.ibm.com> References: <46570DFB.3080101@bull.net> <20070530002100.GV85884050@sgi.com> Reply-To: cmm@us.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, nfsv4@linux-nfs.org, Jean noel Cordenner To: David Chinner Return-path: In-Reply-To: <20070530002100.GV85884050@sgi.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: nfsv4-bounces@linux-nfs.org Errors-To: nfsv4-bounces@linux-nfs.org List-Id: linux-ext4.vger.kernel.org On Wed, 2007-05-30 at 10:21 +1000, David Chinner wrote: > On Fri, May 25, 2007 at 06:25:31PM +0200, Jean noel Cordenner wrote: > > Hi, > > > > This is an update of the i_version patch. > > The i_version field is a 64bit counter that is set on every inode > > creation and that is incremented every time the inode data is modified > > (similarly to the "ctime" time-stamp). > > My understanding (please correct me if I'm wrong) is that the > requirements are much more rigourous than simply incrementing an in > memory counter on every change. i.e. the this counter has to > survive server crashes intact so clients never see the counter go > backwards. That means version number changes need to be journalled > along with the operation that caused the change of the version > number. > Yeah, the i_version is the in memeory counter. From the patch it looks like the counter is being updated inside ext4_mark_iloc_dirty(), so it is being journalled and being flush to on-disk ext4 inode structure immediately (On-disk ext4 inode structure is being modified/expanded to store the counter in the first patch). >This patch is on top of i_version_update_vfs. > The i_version field of the inode is set on inode creation and incremented when > the inode is being modified. > > Signed-off-by: Jean Noel Cordenner > > Index: linux-2.6.22-rc2-ext4-1/fs/ext4/ialloc.c > =================================================================== > --- linux-2.6.22-rc2-ext4-1.orig/fs/ext4/ialloc.c 2007-05-25 18:05:28.000000000 +0200 > +++ linux-2.6.22-rc2-ext4-1/fs/ext4/ialloc.c 2007-05-25 18:05:40.000000000 +0200 > @@ -565,6 +565,7 @@ > inode->i_blocks = 0; > inode->i_mtime = inode->i_atime = inode->i_ctime = ei->i_crtime = > ext4_current_time(inode); > + inode->i_version = 1; > > memset(ei->i_data, 0, sizeof(ei->i_data)); > ei->i_dir_start_lookup = 0; > Index: linux-2.6.22-rc2-ext4-1/fs/ext4/inode.c > =================================================================== > --- linux-2.6.22-rc2-ext4-1.orig/fs/ext4/inode.c 2007-05-25 18:05:28.000000000 +0200 > +++ linux-2.6.22-rc2-ext4-1/fs/ext4/inode.c 2007-05-25 18:05:40.000000000 +0200 > @@ -3082,6 +3082,7 @@ > { > int err = 0; > > + inode->i_version++; > /* the do_update_inode consumes one bh->b_count */ > get_bh(iloc->bh); > > Index: linux-2.6.22-rc2-ext4-1/fs/ext4/super.c > =================================================================== > --- linux-2.6.22-rc2-ext4-1.orig/fs/ext4/super.c 2007-05-25 18:05:28.000000000 +0200 > +++ linux-2.6.22-rc2-ext4-1/fs/ext4/super.c 2007-05-25 18:05:40.000000000 +0200 > @@ -2839,8 +2839,8 @@ > i_size_write(inode, off+len-towrite); > EXT4_I(inode)->i_disksize = inode->i_size; > } > - inode->i_version++; > inode->i_mtime = inode->i_ctime = CURRENT_TIME; > + inode->i_version = 1; > ext4_mark_inode_dirty(handle, inode); > mutex_unlock(&inode->i_mutex); > return len - towrite; I am not very clear about this part -- what is i_version being used for with quota? And shall we reset the counter to 1 for ext4_quota_write()? Mingming