linux-ext4 - Re: Question on fallocate/ftruncate sequence

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Message-Id: <1248389165.17459.3.camel@bobble.smo.corp.google.com>
Date:	Thu, 23 Jul 2009 15:46:05 -0700
From:	Frank Mayhar <fmayhar@...gle.com>
To:	Andreas Dilger <adilger@....com>
Cc:	Eric Sandeen <sandeen@...hat.com>,
	Curt Wohlgemuth <curtw@...gle.com>,
	ext4 development <linux-ext4@...r.kernel.org>
Subject: Re: Question on fallocate/ftruncate sequence

On Thu, 2009-07-23 at 15:56 -0600, Andreas Dilger wrote:
> On Jul 23, 2009  11:05 -0700, Frank Mayhar wrote:
> > On Thu, 2009-07-23 at 12:00 -0500, Eric Sandeen wrote:
> > > Sorry I skimmed to fast, skipped over the fsck part.  But:
> > > 
> > > # touch /mnt/test/testfile
> > > # /root/fallocate -n -l 16m /mnt/test/testfile
> > > # ls -l /mnt/test/testfile
> > > -rw-r--r-- 1 root root 0 Jul 23 12:13 /mnt/test/testfile
> > > # du -h /mnt/test/testfile
> > > 16M	/mnt/test/testfile
> > > 
> > > there doesn't seem to be a problem in fsck w/ block past EOF, or am I
> > > missing something else?
> > 
> > I was taking Andreas' word for it but now that you mention it, I see the
> > same thing.  Andreas, did you have a specific case in mind?
> 
> Ted and I had discussed this in the past, maybe he fixed e2fsck to not
> change the file size when there are blocks allocated beyond EOF.  Having
> a flag wouldn't be a terrible idea, IMHO, so that e2fsck can make a
> better decision on whether the size or the blocks count are more correct.
> I'm not dead set on it.

For the moment I'm going to table the e2fsck change and make the flag
memory-only.  It'll be easy enough to change this if and when you guys
come to an agreement about what is right.

As for the flag itself, I'll pick a bit that doesn't conflict with
anything else and leave reconciling the already-conflicting bits to you
guys.
-- 
Frank Mayhar <fmayhar@...gle.com>
Google, Inc.

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