Re: [PATCH 20/21] xfs: add an experimental feature warning for RT data checksums

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

On Thu, Sep 24, 2026 at 11:59:52AM +0200, Christoph Hellwig wrote:
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  fs/xfs/xfs_message.c | 4 ++++
>  fs/xfs/xfs_message.h | 1 +
>  fs/xfs/xfs_mount.h   | 2 ++
>  fs/xfs/xfs_rtcsum.c  | 2 +-
>  4 files changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/xfs/xfs_message.c b/fs/xfs/xfs_message.c
> index 0243e509a468..53e8ed976a9b 100644
> --- a/fs/xfs/xfs_message.c
> +++ b/fs/xfs/xfs_message.c
> @@ -149,6 +149,10 @@ xfs_warn_experimental(
>  			.opstate	= XFS_OPSTATE_WARNED_LARP,
>  			.name		= "logged extended attributes",
>  		},
> +		[XFS_EXPERIMENTAL_CSUM] = {
> +			.opstate	= XFS_OPSTATE_WARNED_CSUM,
> +			.name		= "data checksum",

Nit: checksums (plural)?  Seeing as the xfs_info() below also says
checksums.

> +		},
>  	};
>  	ASSERT(feat >= 0 && feat < XFS_EXPERIMENTAL_MAX);
>  	BUILD_BUG_ON(ARRAY_SIZE(features) != XFS_EXPERIMENTAL_MAX);
> diff --git a/fs/xfs/xfs_message.h b/fs/xfs/xfs_message.h
> index 811b885f41c3..d858e93e5426 100644
> --- a/fs/xfs/xfs_message.h
> +++ b/fs/xfs/xfs_message.h
> @@ -93,6 +93,7 @@ void xfs_buf_alert_ratelimited(struct xfs_buf *bp, const char *rlmsg,
>  enum xfs_experimental_feat {
>  	XFS_EXPERIMENTAL_SHRINK,
>  	XFS_EXPERIMENTAL_LARP,
> +	XFS_EXPERIMENTAL_CSUM,
>  
>  	XFS_EXPERIMENTAL_MAX,
>  };
> diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
> index fa86697f463a..c62eb42e490a 100644
> --- a/fs/xfs/xfs_mount.h
> +++ b/fs/xfs/xfs_mount.h
> @@ -586,6 +586,8 @@ __XFS_HAS_FEAT(nouuid, NOUUID)
>   */
>  #define XFS_OPSTATE_BLOCKGC_ENABLED	6
>  
> +/* Kernel has logged a warning about checksums */
> +#define XFS_OPSTATE_WARNED_CSUM		8
>  /* Kernel has logged a warning about shrink being used on this fs. */
>  #define XFS_OPSTATE_WARNED_SHRINK	9
>  /* Kernel has logged a warning about logged xattr updates being used. */
> diff --git a/fs/xfs/xfs_rtcsum.c b/fs/xfs/xfs_rtcsum.c
> index 7cdc5a5029eb..47a7b67f7412 100644
> --- a/fs/xfs/xfs_rtcsum.c
> +++ b/fs/xfs/xfs_rtcsum.c
> @@ -310,8 +310,8 @@ xfs_rtcsum_mount(
>  	}
>  	mp->m_features |= XFS_FEAT_DAX_NEVER;
>  
> +	xfs_warn_experimental(mp, XFS_EXPERIMENTAL_CSUM);
>  	xfs_info(mp, "using %s for RT device data checksums",
>  		xfs_data_csum_names[mp->m_sb.sb_rtcsum_type]);
> -

Extraneous deletion?

With that dealt with,
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

--D