linux-kernel - Re: [RFC PATCH V6 7/7] ovl: implement containerized syncfs for overlayfs

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Date:   Fri, 26 Nov 2021 10:25:08 +0100
From:   Jan Kara <jack@...e.cz>
To:     Chengguang Xu <cgxu519@...ernel.net>
Cc:     miklos@...redi.hu, jack@...e.cz, amir73il@...il.com,
        linux-unionfs@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Chengguang Xu <charliecgxu@...cent.com>
Subject: Re: [RFC PATCH V6 7/7] ovl: implement containerized syncfs for
 overlayfs

On Mon 22-11-21 11:00:38, Chengguang Xu wrote:
> From: Chengguang Xu <charliecgxu@...cent.com>
> 
> Now overlayfs can only sync own dirty inodes during syncfs,
> so remove unnecessary sync_filesystem() on upper file system.
> 
> Signed-off-by: Chengguang Xu <charliecgxu@...cent.com>

Looks good. Feel free to add:

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

								Honza

> ---
>  fs/overlayfs/super.c | 14 +++++---------
>  1 file changed, 5 insertions(+), 9 deletions(-)
> 
> diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
> index ccffcd96491d..213b795a6a86 100644
> --- a/fs/overlayfs/super.c
> +++ b/fs/overlayfs/super.c
> @@ -292,18 +292,14 @@ static int ovl_sync_fs(struct super_block *sb, int wait)
>  	/*
>  	 * Not called for sync(2) call or an emergency sync (SB_I_SKIP_SYNC).
>  	 * All the super blocks will be iterated, including upper_sb.
> -	 *
> -	 * If this is a syncfs(2) call, then we do need to call
> -	 * sync_filesystem() on upper_sb, but enough if we do it when being
> -	 * called with wait == 1.
>  	 */
> -	if (!wait)
> -		return 0;
> -
>  	upper_sb = ovl_upper_mnt(ofs)->mnt_sb;
> -
>  	down_read(&upper_sb->s_umount);
> -	ret = sync_filesystem(upper_sb);
> +	if (wait)
> +		wait_sb_inodes(upper_sb);
> +	if (upper_sb->s_op->sync_fs)
> +		upper_sb->s_op->sync_fs(upper_sb, wait);
> +	ret = ovl_sync_upper_blockdev(upper_sb, wait);
>  	up_read(&upper_sb->s_umount);
>  
>  	return ret;
> -- 
> 2.27.0
> 
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR