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Date:   Tue, 15 Jun 2021 09:52:32 +0200
From:   Jan Kara <jack@suse.cz>
To:     Andreas Dilger <adilger@dilger.ca>
Cc:     Jan Kara <jack@suse.cz>, Ted Tso <tytso@mit.edu>,
        Ext4 Developers List <linux-ext4@vger.kernel.org>
Subject: Re: [PATCH] tune2fs: Update overhead when toggling journal feature
Message-ID: <20210615075232.GE29751@quack2.suse.cz>
References: <20210614212830.20207-1-jack@suse.cz>
 <E6977B7F-091D-40E9-B0CD-BB3D8B7FE287@dilger.ca>
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On Mon 14-06-21 15:38:57, Andreas Dilger wrote:
> 
> > On Jun 14, 2021, at 3:28 PM, Jan Kara <jack@suse.cz> wrote:
> > 
> > When adding or removing journal from a filesystem, we also need to add /
> > remove journal blocks from overhead stored in the superblock.  Otherwise
> > total number of blocks in the filesystem as reported by statfs(2) need
> > not match reality and could lead to odd results like negative number of
> > used blocks reported by df(1).
> > 
> > Signed-off-by: Jan Kara <jack@suse.cz>
> 
> You could add:
> 
> Fixes: 9046b4dfd0ce ("mke2fs: set overhead in super block")
> 
> and
> 
> Reviewed-by: Andreas Dilger <adilger@dilger.ca>

Thanks!

> That also makes me wonder if resize2fs also needs to recalculate or
> invalidate the s_overhead_clusters field when adding new block groups.
> It *looks* like that is done correctly in adjust_fs_info() already?

Yes. From a quick look I had when doing this tune2fs patch I've noticed
that adjust_fs_info() just zeros s_overhead_clusters which makes the kernel
compute the overhead instead...

								Honza

-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR