linux-ext4 - Re: nolazytime remount

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Message-ID: <20150824092900.GN1689@ws.net.home>
Date:	Mon, 24 Aug 2015 11:29:00 +0200
From:	Karel Zak <kzak@...hat.com>
To:	tytso@....edu
Cc:	linux-ext4@...r.kernel.org
Subject: Re: nolazytime remount

On Wed, Aug 19, 2015 at 02:15:16PM +0000, tytso@....edu wrote:
> I *think* the number of people who would want to disable lazytime is
> smaller, which why I made the decision that I did, so my thinking was
> to leave it this way until the next version of Debian stable ships,
> and then change the kernel to allow the newer versions of mount to
> disable lazytime at that point.

Yes, I think the long term solution is to support MS_LAZYTIME flags
only and remove "[no]lazytime" strings from ext4 mount options parser.

> I suppose I could set up make this be switchable, so people could
> specify ext4.support_older_mount=1 on the boot command-line option,
> but this seems really ugly, and then people would need to remember to
> remove said ugly command-line option from their grub config file when
> they update to a newer mount command.

It seems like over-engineering to introduce another comman-line option
to fix the current mount option. It would be better to keep it simple
and stupid :-)

If you want to make it configurable than use #ifdef and kconfig --
then distros like Debian may enable the obsolete string-based
"lazytime".

I don't think we have to support all permutation without kernel
recompilation, the important is to support generic use-cases and allow
to distros to compose and distribute consistent stuff. The current
situation when you have new kernel, new mount(8), but you cannot
"-o remount,nolazytime" is bad.

    Karel

-- 
 Karel Zak  <kzak@...hat.com>
 http://karelzak.blogspot.com
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