From: "Aneesh Kumar K. V" <aneesh.kumar@linux.vnet.ibm.com>
Subject: Re: [PATCH] ext4: Do not zeroout uninitialized extents beyond i_size
Date: Thu, 27 May 2010 22:49:43 +0530
Message-ID: <87d3whuus0.fsf@linux.vnet.ibm.com>
References: <1270833748-14381-1-git-send-email-dmonakhov@openvz.org> <87och49oly.fsf@linux.vnet.ibm.com> <871ve0qb59.fsf@openvz.org>
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Cc: linux-ext4@vger.kernel.org, tytso@mit.edu
To: Dmitry Monakhov <dmonakhov@openvz.org>
In-Reply-To: <871ve0qb59.fsf@openvz.org>
Sender: linux-ext4-owner@vger.kernel.org

On Wed, 28 Apr 2010 11:38:58 +0400, Dmitry Monakhov <dmonakhov@openvz.org> wrote:
> "Aneesh Kumar K. V" <aneesh.kumar@linux.vnet.ibm.com> writes:
> 
> > On Fri,  9 Apr 2010 21:22:28 +0400, Dmitry Monakhov <dmonakhov@openvz.org> wrote:
> >> Zerrout trick allow us to optimize cases where it is more reasonable
> >> to explicitly zeroout extent and mark it as initialized instead of
> >> splitting to several small ones.
> >> But this optimization is not acceptable is extent is beyond i_size
> >> Because it is not possible to have initialized blocks after i_size.
> >> Fsck treat this as incorrect inode size.
> >> 
> >
> > With commit c8d46e41bc744c8fa0092112af3942fcd46c8b18 if we set
> > EXT4_EOFBLOCKS_FL we should be able to have blocks beyond i_size.
> > May be the zero out path should set the flag instead of doing all these
> > changes. Zero-out is already complex with all the ENOSPC related
> > consideration. I guess we should try to keep it simple.
> For initialized extent beyond i_size? I've check fsck and seems that
> is truly possible. So this optimization allow us to avoid some 
> bad EIO situations. But we have to rework ext_get_blocks( ,create == 1)
> to clear EXT4_EOFBLOCKS_FL if last block of latest_extent is requested.
> I'll handle this.
> >


I thought this patch is going to reworked to use EOFBLOCKS_FL. But i see
Ted sent a pull request with the this patch. Did I miss something ?

-aneesh