Re: [PATCH 7/8] xfs: fix off-by-one error in xfs_rtalloc_query_range

[Allison Henderson <allison.henderson@oracle.com>]

Looks good:
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>

On 06/21/2018 11:31 AM, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> In commit 8ad560d2565e6 ("xfs: strengthen rtalloc query range checks")
> we strengthened the input parameter checks in the rtbitmap range query
> function, but introduced an off-by-one error in the process.  The call
> to xfs_rtfind_forw deals with the high key being rextents, but we clamp
> the high key to rextents - 1.  This causes the returned results to stop
> one block short of the end of the rtdev, which is incorrect.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
>   fs/xfs/libxfs/xfs_rtbitmap.c |    4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> 
> diff --git a/fs/xfs/libxfs/xfs_rtbitmap.c b/fs/xfs/libxfs/xfs_rtbitmap.c
> index 65fc4ed2e9a1..b228c821bae6 100644
> --- a/fs/xfs/libxfs/xfs_rtbitmap.c
> +++ b/fs/xfs/libxfs/xfs_rtbitmap.c
> @@ -1029,8 +1029,8 @@ xfs_rtalloc_query_range(
>   	if (low_rec->ar_startext >= mp->m_sb.sb_rextents ||
>   	    low_rec->ar_startext == high_rec->ar_startext)
>   		return 0;
> -	if (high_rec->ar_startext >= mp->m_sb.sb_rextents)
> -		high_rec->ar_startext = mp->m_sb.sb_rextents - 1;
> +	if (high_rec->ar_startext > mp->m_sb.sb_rextents)
> +		high_rec->ar_startext = mp->m_sb.sb_rextents;
>   
>   	/* Iterate the bitmap, looking for discrepancies. */
>   	rtstart = low_rec->ar_startext;
> 
> --
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