linux-ext4 - Re: BUG with delayed allocation

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Message-ID: <20080320175625.GA6931@skywalker>
Date:	Thu, 20 Mar 2008 23:26:25 +0530
From:	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
To:	Mingming Cao <cmm@...ibm.com>
Cc:	Eric Sandeen <sandeen@...hat.com>,
	ext4 <linux-ext4@...r.kernel.org>
Subject: Re: BUG with delayed allocation

On Thu, Mar 20, 2008 at 10:29:50AM -0700, Mingming Cao wrote:
> On Thu, 2008-03-20 at 11:09 +0530, Aneesh Kumar K.V wrote:
> 
> > > Could you try the following patch? It updates the i_disksize at the
> > > write_end time.
> > > 
> > 
> > I will test the patch and update you. BTW shouldn't we update
> > i_disksize only after actual block got allocated ?
> > 
> > 
> Hmm...I am not  100% sure but I think we should not to change the
> behavior that the on-disk inode size should be updated when write()
> returns to user. Right now the in-memory inode size is updated, user
> would expecting the same when they run e2fsck, but e2fsck reads inode
> size from disk. Pushing the inode i_disksize update at the writeout
> (allocation) time will cause the window that i_size is different than
> the i_disksize being enlarged quite big.
> 

If we are updating i_disksize during write_end and if we crash before actually
allocating the blocks e2fsck will find errors because the inode doesn't
really have that many blocks right ?


-aneesh
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