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Re: [PATCH 1/6] ext4: Update inode i_size after the preallocation

To: "Theodore Ts'o" <tytso@xxxxxxx>
Subject: Re: [PATCH 1/6] ext4: Update inode i_size after the preallocation
From: Lukáš Czerner <lczerner@xxxxxxxxxx>
Date: Tue, 18 Feb 2014 09:13:17 +0100 (CET)
Cc: Andreas Dilger <adilger@xxxxxxxxx>, Ext4 Developers List <linux-ext4@xxxxxxxxxxxxxxx>, linux-fsdevel <linux-fsdevel@xxxxxxxxxxxxxxx>, xfs@xxxxxxxxxxx
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In-reply-to: <20140217232100.GA26580@xxxxxxxxx>
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On Mon, 17 Feb 2014, Theodore Ts'o wrote:

> Date: Mon, 17 Feb 2014 18:21:00 -0500
> From: Theodore Ts'o <tytso@xxxxxxx>
> To: Andreas Dilger <adilger@xxxxxxxxx>
> Cc: Lukas Czerner <lczerner@xxxxxxxxxx>,
>     Ext4 Developers List <linux-ext4@xxxxxxxxxxxxxxx>,
>     linux-fsdevel <linux-fsdevel@xxxxxxxxxxxxxxx>, xfs@xxxxxxxxxxx
> Subject: Re: [PATCH 1/6] ext4: Update inode i_size after the preallocation
> 
> On Mon, Feb 17, 2014 at 04:12:14PM -0700, Andreas Dilger wrote:
> > 
> > I don't necessarily agree about this.  Calling fallocate() will not
> > change the user-visible data at all, so there is no reason to e.g.
> > do a new backup of the file or reprocess the contents, or any other
> > reason that an application cares about a changed mtime.
> 
> Well, if i_size has changed, then the visible results of reading from
> the file will change, so in that case I'd argue m_time should change.
> If the results of reading file doesn't change then we can keep m_time
> unchanged --- but since the inode is changing, c_time *should* always
> change any time we've made any changes to the extent tree.
> 
>                                    - Ted

So I guess the consensus is to update m_time only when the inode size
changes in fallocate case. I'll change that in the code.

Thanks!
-Lukas

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