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Date:   Sat, 10 Dec 2022 19:12:58 +0000
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     Chen Zhongjin <chenzhongjin@huawei.com>
Cc:     linux-kernel@vger.kernel.org, hch@infradead.org
Subject: Re: [PATCH] fs: sysv: Fix sysv_nblocks() returns wrong value
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On Fri, Dec 09, 2022 at 06:04:48PM +0800, Chen Zhongjin wrote:
> sysv_nblocks() returns 'blocks' rather than 'res', which only counting
> the number of triple-indirect blocks and causing sysv_getattr() gets a
> wrong result.
> 
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Chen Zhongjin <chenzhongjin@huawei.com>
> ---
>  fs/sysv/itree.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/sysv/itree.c b/fs/sysv/itree.c
> index d4ec9bb97de9..3b8567564e7e 100644
> --- a/fs/sysv/itree.c
> +++ b/fs/sysv/itree.c
> @@ -438,7 +438,7 @@ static unsigned sysv_nblocks(struct super_block *s, loff_t size)
>  		res += blocks;
>  		direct = 1;
>  	}
> -	return blocks;
> +	return res;
>  }
>  
>  int sysv_getattr(struct user_namespace *mnt_userns, const struct path *path,

Argh...

To quote historical tree:
commit 0fcd426de9d02175c9771ea19f972389eeba7688
Author: Andries E. Brouwer <andries.brouwer@cwi.nl>
Date:   Sun Aug 22 00:07:46 2004 -0700

    [PATCH] minix block usage counting fix
    
    In 2.5.18 some minix-specific stuff was moved to the minix subdirectory
    where it belonged.  However, a typo crept in, causing inode disk usage
    to be incorrectly reported.  A few people have complained, but so far
    not sufficiently loudly.
    
    Signed-off-by: Andries Brouwer <Andries.Brouwer@cwi.nl>
    Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/fs/minix/itree_common.c b/fs/minix/itree_common.c
index f8e9bd831c90..5a4b51dbfcb3 100644
--- a/fs/minix/itree_common.c
+++ b/fs/minix/itree_common.c
@@ -358,5 +358,5 @@ static inline unsigned nblocks(loff_t size)
                res += blocks;
                direct = 1;
        }
-       return blocks;
+       return res;
 }


This is obviously the sysvfs counterpart, not noticed back then and
not caught in 18 years since then...

Mea culpa - the original bug (both in minixfs and sysvfs) is mine and
I should've thought to look for sysvfs counterpart when minixfs fix
got posted.

Applied.