xfs: check that CoW fork extents are not shared

Ensure that extents in an inode's CoW fork are not marked as shared in
the refcount btree.
Signed-off-by: NDarrick J. Wong <djwong@kernel.org>
Reviewed-by: NDave Chinner <dchinner@redhat.com>

fs/xfs/scrub/bmap.c

@@ -335,6 +335,8 @@ xchk_bmap_iextent_xref(
 	case XFS_COW_FORK:
 		xchk_xref_is_cow_staging(info->sc, agbno,
 				irec->br_blockcount);
+		xchk_xref_is_not_shared(info->sc, agbno,
+				irec->br_blockcount);
 		break;
 	}