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Date:   Wed, 30 Mar 2022 08:42:17 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     Liu Shixin <liushixin2@huawei.com>
Cc:     Christoph Hellwig <hch@infradead.org>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH -next] fs: sysv: check sbi->s_firstdatazone in
 complete_read_super
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On Wed, Mar 30, 2022 at 06:42:15PM +0800, Liu Shixin wrote:
> sbi->s_firstinodezone is initialized to 2 and sbi->s_firstdatazone is read
> from sbd. There's no guarantee that sbi->s_firstdatazone must bigger than
> sbi->s_firstinodezone. If sbi->s_firstdatazone less than 2, the filesystem
> can still be mounted unexpetly. At this point, sbi->s_ninodes flip to very
> large value and this filesystem is broken. We can observe this by
> executing 'df' command. When we execute, we will get an error message:
> 	"sysv_count_free_inodes: unable to read inode table"

This looks fine.  Just curious: which variant of the sysv fs do you
use and what is the use case?