Re: [PATCH 1/2] fs: initialize inode->__i_ctime to the epoch

From: Jan Kara <jack@suse.cz>
To: Jeff Layton <jlayton@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
	Christian Brauner <brauner@kernel.org>, Jan Kara <jack@suse.cz>,
	linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	kernel test robot <oliver.sang@intel.com>
Subject: Re: [PATCH 1/2] fs: initialize inode->__i_ctime to the epoch
Date: Fri, 8 Sep 2023 12:42:29 +0200	[thread overview]
Message-ID: <20230908104229.5tsr2sn7oyfy53ih@quack3> (raw)
In-Reply-To: <20230907-ctime-fixes-v1-1-3b74c970d934@kernel.org>

On Thu 07-09-23 12:33:47, Jeff Layton wrote:
> With the advent of multigrain timestamps, we use inode_set_ctime_current
> to set the ctime, which can skip updating if the existing ctime appears
> to be in the future. Because we don't initialize this field at
> allocation time, that could prevent the ctime from being initialized
> properly when the inode is instantiated.
> 
> Always initialize the ctime field to the epoch so that the filesystem
> can set the timestamps properly later.
> 
> Reported-by: kernel test robot <oliver.sang@intel.com>
> Closes: https://lore.kernel.org/oe-lkp/202309071017.a64aca5e-oliver.sang@intel.com
> Signed-off-by: Jeff Layton <jlayton@kernel.org>

Looks good but don't you need the same treatment to atime after your patch
2/2?

								Honza

> ---
>  fs/inode.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/fs/inode.c b/fs/inode.c
> index 35fd688168c5..54237f4242ff 100644
> --- a/fs/inode.c
> +++ b/fs/inode.c
> @@ -168,6 +168,8 @@ int inode_init_always(struct super_block *sb, struct inode *inode)
>  	inode->i_fop = &no_open_fops;
>  	inode->i_ino = 0;
>  	inode->__i_nlink = 1;
> +	inode->__i_ctime.tv_sec = 0;
> +	inode->__i_ctime.tv_nsec = 0;
>  	inode->i_opflags = 0;
>  	if (sb->s_xattr)
>  		inode->i_opflags |= IOP_XATTR;
> 
> -- 
> 2.41.0
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR