linux-kernel - Re: [PATCH 1/3] xfs: fix the calculation of length and end

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Message-ID: <YyIZyE7I0ewoxtgj@magnolia>
Date:   Wed, 14 Sep 2022 11:13:28 -0700
From:   "Darrick J. Wong" <djwong@...nel.org>
To:     Shiyang Ruan <ruansy.fnst@...itsu.com>
Cc:     linux-kernel@...r.kernel.org, linux-xfs@...r.kernel.org,
        nvdimm@...ts.linux.dev, linux-mm@...ck.org,
        linux-fsdevel@...r.kernel.org, dan.j.williams@...el.com,
        david@...morbit.com, hch@...radead.org, jane.chu@...cle.com
Subject: Re: [PATCH 1/3] xfs: fix the calculation of length and end

On Fri, Sep 02, 2022 at 10:35:59AM +0000, Shiyang Ruan wrote:
> The end should be start + length - 1.  Also fix the calculation of the
> length when seeking for intersection of notify range and device.
> 
> Signed-off-by: Shiyang Ruan <ruansy.fnst@...itsu.com>

Looks correct to me,
Reviewed-by: Darrick J. Wong <djwong@...nel.org>

--D

> ---
>  fs/xfs/xfs_notify_failure.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/xfs/xfs_notify_failure.c b/fs/xfs/xfs_notify_failure.c
> index c4078d0ec108..3830f908e215 100644
> --- a/fs/xfs/xfs_notify_failure.c
> +++ b/fs/xfs/xfs_notify_failure.c
> @@ -114,7 +114,7 @@ xfs_dax_notify_ddev_failure(
>  	int			error = 0;
>  	xfs_fsblock_t		fsbno = XFS_DADDR_TO_FSB(mp, daddr);
>  	xfs_agnumber_t		agno = XFS_FSB_TO_AGNO(mp, fsbno);
> -	xfs_fsblock_t		end_fsbno = XFS_DADDR_TO_FSB(mp, daddr + bblen);
> +	xfs_fsblock_t		end_fsbno = XFS_DADDR_TO_FSB(mp, daddr + bblen - 1);
>  	xfs_agnumber_t		end_agno = XFS_FSB_TO_AGNO(mp, end_fsbno);
>  
>  	error = xfs_trans_alloc_empty(mp, &tp);
> @@ -210,7 +210,7 @@ xfs_dax_notify_failure(
>  	ddev_end = ddev_start + bdev_nr_bytes(mp->m_ddev_targp->bt_bdev) - 1;
>  
>  	/* Ignore the range out of filesystem area */
> -	if (offset + len < ddev_start)
> +	if (offset + len - 1 < ddev_start)
>  		return -ENXIO;
>  	if (offset > ddev_end)
>  		return -ENXIO;
> @@ -222,8 +222,8 @@ xfs_dax_notify_failure(
>  		len -= ddev_start - offset;
>  		offset = 0;
>  	}
> -	if (offset + len > ddev_end)
> -		len -= ddev_end - offset;
> +	if (offset + len - 1 > ddev_end)
> +		len -= offset + len - 1 - ddev_end;
>  
>  	return xfs_dax_notify_ddev_failure(mp, BTOBB(offset), BTOBB(len),
>  			mf_flags);
> -- 
> 2.37.2
>