linux-kernel - Re: ext4 ignoring rootfs default mount options

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Message-ID: <20180307225043.GA15217@thunk.org>
Date:   Wed, 7 Mar 2018 17:50:43 -0500
From:   "Theodore Y. Ts'o" <tytso@....edu>
To:     Lennart Sorensen <lsorense@...lub.uwaterloo.ca>
Cc:     Andreas Dilger <adilger.kernel@...ger.ca>,
        linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: ext4 ignoring rootfs default mount options

On Wed, Mar 07, 2018 at 02:13:24PM -0500, Lennart Sorensen wrote:
> 
> Trying to use tune2fs -E mount_opts to set some default options, and
> can't figure out how to enter two options at once.
>
> ...
>
> Sure in this case I can set one with -o and the other with -E, but in
> general there seems to be a small problem here, probably only in user
> space though.  Seems tune2fs needs some change in how it deals with
> extended options that contain commas.

Yes, this is a shortcoming in tune2fs.  You can set extended mount
options using debugfs:

    debugfs -w -R "set_super_value mount_opts foo,bar" /dev/sda1

... but there ought to be some way to support some kind of quoting
mechanism so that tune2fs can understand when a comma is part of an
extended option value, as opposed to separating extended options.

Extended options haven't been used much, so it's not been something
that has gotten a lot of polish.  Backing up for a bit, is there a
reason why you need so many mount options when mounting the root file
sytsem?  Specifically, why do you want to turn off dellayed allocation?

	 	       	      	       	  - Ted