xfs: fix off-by-one error in xfs_rtalloc_query_range

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>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

diff --git a/fs/xfs/libxfs/xfs_rtbitmap.c b/fs/xfs/libxfs/xfs_rtbitmap.c
index 65fc4ed2e9a1050b76b1cd85d874294e52a8afd9..b228c821bae6802c0aa8ab9b79069d703245bbe2 100644 (file)
--- 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;