xfs: don't coalesce file mappings that cross rtgroup boundaries in scrub

The bmbt scrubber will combine file mappings if they are mergeable to
reduce the number of cross-referencing checks.  However, we shouldn't
combine mappings that cross rt group boundaries because that will cause
verifiers to trip incorrectly.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

Author: Darrick J. Wong

fs/xfs/scrub/bmap.c

@@ -834,9 +834,12 @@ xchk_bmap_iext_mapping(
 /* Are these two mappings contiguous with each other? */
 static inline bool
 xchk_are_bmaps_contiguous(
+	const struct xchk_bmap_info	*info,
 	const struct xfs_bmbt_irec	*b1,
 	const struct xfs_bmbt_irec	*b2)
 {
+	struct xfs_mount		*mp = info->sc->mp;
+
 	/* Don't try to combine unallocated mappings. */
 	if (!xfs_bmap_is_real_extent(b1))
 		return false;
@@ -850,6 +853,17 @@ xchk_are_bmaps_contiguous(
 		return false;
 	if (b1->br_state != b2->br_state)
 		return false;
+
+	/*
+	 * Don't combine bmaps that would cross rtgroup boundaries.  This is a
+	 * valid state, but if combined they will fail rtb extent checks.
+	 */
+	if (info->is_rt && xfs_has_rtgroups(mp)) {
+		if (xfs_rtb_to_rgno(mp, b1->br_startblock) !=
+		    xfs_rtb_to_rgno(mp, b2->br_startblock))
+			return false;
+	}
+
 	return true;
 }
 
@@ -887,7 +901,7 @@ xchk_bmap_iext_iter(
 	 * that we just read, if possible.
 	 */
 	while (xfs_iext_peek_next_extent(ifp, &info->icur, &got)) {
-		if (!xchk_are_bmaps_contiguous(irec, &got))
+		if (!xchk_are_bmaps_contiguous(info, irec, &got))
 			break;
 
 		if (!xchk_bmap_iext_mapping(info, &got)) {