Re: [PATCH v4 2/3] xfs: introduce xfs_validate_stripe_factors()

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Wed, Oct 07, 2020 at 10:04:01PM +0800, Gao Xiang wrote:
> From: Gao Xiang <hsiangkao@redhat.com>
> 
> Introduce a common helper to consolidate
> stripe validation process. Also make kernel
> code xfs_validate_sb_common() use it first.

Please use all 72(?) columns here.

> 
> Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
> ---
>  libxfs/xfs_sb.c | 54 +++++++++++++++++++++++++++++++++++++++----------
>  libxfs/xfs_sb.h |  3 +++

These libxfs changes will have to go through the kernel first.

>  2 files changed, 46 insertions(+), 11 deletions(-)
> 
> diff --git a/libxfs/xfs_sb.c b/libxfs/xfs_sb.c
> index d37d60b39a52..bd65828c844e 100644
> --- a/libxfs/xfs_sb.c
> +++ b/libxfs/xfs_sb.c
> @@ -357,21 +357,13 @@ xfs_validate_sb_common(
>  		}
>  	}
>  
> -	if (sbp->sb_unit) {
> -		if (!xfs_sb_version_hasdalign(sbp) ||
> -		    sbp->sb_unit > sbp->sb_width ||
> -		    (sbp->sb_width % sbp->sb_unit) != 0) {
> -			xfs_notice(mp, "SB stripe unit sanity check failed");
> -			return -EFSCORRUPTED;
> -		}
> -	} else if (xfs_sb_version_hasdalign(sbp)) {
> +	if (!sbp->sb_unit ^ !xfs_sb_version_hasdalign(sbp)) {

Urgh, this logic makes my brain hurt.

"If the zeroness of sb_unit differs from the unsetness of the dalign
feature"?  This might need some kind of comment, such as:

	/*
	 * Either sb_unit and hasdalign are both set, or they are zero
	 * and not set, respectively.
	 */
	if (!sbp->sb_unit ^ !xfs_sb_version_hasdalign(sbp)) {

>  		xfs_notice(mp, "SB stripe alignment sanity check failed");
>  		return -EFSCORRUPTED;
> -	} else if (sbp->sb_width) {
> -		xfs_notice(mp, "SB stripe width sanity check failed");
> -		return -EFSCORRUPTED;
>  	}
>  
> +	if (!xfs_validate_stripe_factors(mp, sbp->sb_unit, sbp->sb_width, 0))
> +		return -EFSCORRUPTED;
>  
>  	if (xfs_sb_version_hascrc(&mp->m_sb) &&
>  	    sbp->sb_blocksize < XFS_MIN_CRC_BLOCKSIZE) {
> @@ -1208,3 +1200,43 @@ xfs_sb_get_secondary(
>  	*bpp = bp;
>  	return 0;
>  }
> +
> +/*
> + * If sectorsize is specified, sunit / swidth must be in bytes;
> + * or both can be in any kind of units (e.g. 512B sector or blocksize).
> + */
> +bool
> +xfs_validate_stripe_factors(
> +	struct xfs_mount	*mp,
> +	int			sunit,
> +	int			swidth,
> +	int			sectorsize)
> +{
> +	if (sectorsize && sunit % sectorsize) {
> +		xfs_notice(mp,
> +"stripe unit (%d) must be a multiple of the sector size (%d)",
> +			   sunit, sectorsize);
> +		return false;
> +	}
> +
> +	if ((sunit && !swidth) || (!sunit && swidth)) {
> +		xfs_notice(mp,
> +"stripe unit (%d) and width (%d) are partially valid", sunit, swidth);

I would break these into separate checks and messages.

> +		return false;
> +	}
> +
> +	if (sunit > swidth) {
> +		xfs_notice(mp,
> +"stripe unit (%d) is too large of the stripe width (%d)", sunit, swidth);

"stripe unit (%d) is larger than the stripe width..."

--D

> +		return false;
> +	}
> +
> +	if (sunit && (swidth % sunit)) {
> +		xfs_notice(mp,
> +"stripe width (%d) must be a multiple of the stripe unit (%d)",
> +			   swidth, sunit);
> +		return false;
> +	}
> +	return true;
> +}
> +
> diff --git a/libxfs/xfs_sb.h b/libxfs/xfs_sb.h
> index 92465a9a5162..015b2605f587 100644
> --- a/libxfs/xfs_sb.h
> +++ b/libxfs/xfs_sb.h
> @@ -42,4 +42,7 @@ extern int	xfs_sb_get_secondary(struct xfs_mount *mp,
>  				struct xfs_trans *tp, xfs_agnumber_t agno,
>  				struct xfs_buf **bpp);
>  
> +extern bool	xfs_validate_stripe_factors(struct xfs_mount *mp,
> +				int sunit, int swidth, int sectorsize);
> +
>  #endif	/* __XFS_SB_H__ */
> -- 
> 2.24.0
>