Re: [PATCH] mkfs: require reflink for max_atomic_write option

["Darrick J. Wong" <djwong@kernel.org>]

On Wed, Jul 30, 2025 at 10:13:20AM +0000, John Garry wrote:
> For max_atomic_write option to be set, it means that the user wants to
> support atomic writes up to that size.
> 
> However, to support this we must have reflink, so enforce that this is
> available.
> 
> Signed-off-by: John Garry <john.g.garry@oracle.com>
> Suggested-by: "Darrick J. Wong" <djwong@kernel.org>

Yeah, makes sense to me :P
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

--D

> 
> diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
> index b889c0de..8cd4ccd7 100644
> --- a/mkfs/xfs_mkfs.c
> +++ b/mkfs/xfs_mkfs.c
> @@ -3101,6 +3101,12 @@ _("metadir not supported without exchange-range support\n"));
>  		cli->sb_feat.exchrange = true;
>  	}
>  
> +	if (cli_opt_set(&iopts, I_MAX_ATOMIC_WRITE) && !cli->sb_feat.reflink) {
> +		fprintf(stderr,
> +_("max_atomic_write option not supported without reflink support\n"));
> +		usage();
> +	}
> +
>  	/*
>  	 * Copy features across to config structure now.
>  	 */
> -- 
> 2.43.5
> 
>