linux-ext4 - Re: [PATCH] ext2: compare old and new mode before setting update

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Message-ID: <20181119100425.GD16427@quack2.suse.cz>
Date:   Mon, 19 Nov 2018 11:04:25 +0100
From:   Jan Kara <jack@...e.cz>
To:     Chengguang Xu <cgxu519@....com>
Cc:     jack@...e.com, linux-ext4@...r.kernel.org
Subject: Re: [PATCH] ext2: compare old and new mode before setting
 update_mode flag

On Sat 17-11-18 17:01:00, Chengguang Xu wrote:
> If new mode is the same as old mode we don't have to reset
> inode mode in the rest of the code, so compare old and new
> mode before setting update_mode flag.
> 
> Signed-off-by: Chengguang Xu <cgxu519@....com>

I don't think this is quite correct. E.g. I would think that i_ctime should
be updated even if the effective mode resulting from acl did not change.

								Honza

> ---
>  fs/ext2/acl.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/ext2/acl.c b/fs/ext2/acl.c
> index cf4c77f8dd08..f4dd728393c8 100644
> --- a/fs/ext2/acl.c
> +++ b/fs/ext2/acl.c
> @@ -226,7 +226,8 @@ ext2_set_acl(struct inode *inode, struct posix_acl *acl, int type)
>  		error = posix_acl_update_mode(inode, &mode, &acl);
>  		if (error)
>  			return error;
> -		update_mode = 1;
> +		if (mode != inode->i_mode)
> +			update_mode = 1;
>  	}
>  	error = __ext2_set_acl(inode, acl, type);
>  	if (!error && update_mode) {
> -- 
> 2.17.2
> 
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR