Re: [PATCH -next] fs: sysv: check sbi->s_firstdatazone in complete_read_super

[Christoph Hellwig]

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?