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Re: Documenting MS_LAZYTIME

To: "Michael Kerrisk (man-pages)" <mtk.manpages@xxxxxxxxx>
Subject: Re: Documenting MS_LAZYTIME
From: Theodore Ts'o <tytso@xxxxxxx>
Date: Thu, 26 Feb 2015 08:31:13 -0500
Cc: Eric Sandeen <sandeen@xxxxxxxxxx>, Ext4 Developers List <linux-ext4@xxxxxxxxxxxxxxx>, Linux btrfs Developers List <linux-btrfs@xxxxxxxxxxxxxxx>, XFS Developers <xfs@xxxxxxxxxxx>, linux-man@xxxxxxxxxxxxxxx, Linux-Fsdevel <linux-fsdevel@xxxxxxxxxxxxxxx>, Linux API <linux-api@xxxxxxxxxxxxxxx>
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On Thu, Feb 26, 2015 at 09:49:39AM +0100, Michael Kerrisk (man-pages) wrote:
> > How about somethign like "This mount significantly reduces writes
> > needed to update the inode's timestamps, especially mtime and actime.
> 
> What is "actime" in the preceding line? Should it be "ctime"?

Sorry, no, it should be "atime".

> I find the wording of there a little confusing. Is the following 
> a correct rewrite:
> 
>     The advantage of MS_STRICTATIME | MS_LAZYTIME is that stat(2)
>     will return the correctly updated atime, but the atime updates
>     will be flushed to disk only when (1) the inode needs to be 
>     updated for filesystem / data consistency reasons or (2) the 
>     inode is pushed out of memory, or (3) the filesystem is 
>     unmounted.)

Yes, that's correct.  The only other thing I might add is that in the
case of a crash, the atime (or mtime) fields on disk might be out of
date by at most 24 hours.

                                                - Ted

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