linux-kernel - Re: [PATCH] f2fs: fix to avoid dirent corruption

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Message-ID: <20231128110301.pk3qbhopptmhvxet@quack3>
Date:   Tue, 28 Nov 2023 12:03:01 +0100
From:   Jan Kara <jack@...e.cz>
To:     Chao Yu <chao@...nel.org>
Cc:     jaegeuk@...nel.org, linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, Jan Kara <jack@...e.cz>,
        Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH] f2fs: fix to avoid dirent corruption

On Tue 28-11-23 17:25:16, Chao Yu wrote:
> As Al reported in link[1]:
> 
> f2fs_rename()
> ...
> 	if (old_dir != new_dir && !whiteout)
> 		f2fs_set_link(old_inode, old_dir_entry,
> 					old_dir_page, new_dir);
> 	else
> 		f2fs_put_page(old_dir_page, 0);
> 
> You want correct inumber in the ".." link.  And cross-directory
> rename does move the source to new parent, even if you'd been asked
> to leave a whiteout in the old place.
> 
> [1] https://lore.kernel.org/all/20231017055040.GN800259@ZenIV/
> 
> With below testcase, it may cause dirent corruption, due to it missed
> to call f2fs_set_link() to update ".." link to new directory.
> - mkdir -p dir/foo
> - renameat2 -w dir/foo bar
> 
> [ASSERT] (__chk_dots_dentries:1421)  --> Bad inode number[0x4] for '..', parent parent ino is [0x3]
> [FSCK] other corrupted bugs                           [Fail]
> 
> Fixes: 7e01e7ad746b ("f2fs: support RENAME_WHITEOUT")
> Cc: Jan Kara <jack@...e.cz>
> Reported-by: Al Viro <viro@...iv.linux.org.uk>
> Signed-off-by: Chao Yu <chao@...nel.org>

Thanks for fixing this! Makes sense to me so feel free to add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza

> ---
>  fs/f2fs/namei.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
> index 3b1793cfb002..ede6afb81762 100644
> --- a/fs/f2fs/namei.c
> +++ b/fs/f2fs/namei.c
> @@ -1105,7 +1105,7 @@ static int f2fs_rename(struct mnt_idmap *idmap, struct inode *old_dir,
>  	}
>  
>  	if (old_dir_entry) {
> -		if (old_dir != new_dir && !whiteout)
> +		if (old_dir != new_dir)
>  			f2fs_set_link(old_inode, old_dir_entry,
>  						old_dir_page, new_dir);
>  		else
> -- 
> 2.40.1
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR