xfs: convert unwritten status of reverse mappings

Provide a function to convert an unwritten rmap extent to a real one
and vice versa.

[ dchinner: Note that this algorithm and code was derived from the
  existing bmapbt unwritten extent conversion code in
  xfs_bmap_add_extent_unwritten_real(). ]
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

fs/xfs/xfs_trace.h

@@ -2499,6 +2499,10 @@ DEFINE_AG_ERROR_EVENT(xfs_rmap_unmap_error);
 DEFINE_RMAP_EVENT(xfs_rmap_map);
 DEFINE_RMAP_EVENT(xfs_rmap_map_done);
 DEFINE_AG_ERROR_EVENT(xfs_rmap_map_error);
+DEFINE_RMAP_EVENT(xfs_rmap_convert);
+DEFINE_RMAP_EVENT(xfs_rmap_convert_done);
+DEFINE_AG_ERROR_EVENT(xfs_rmap_convert_error);
+DEFINE_AG_ERROR_EVENT(xfs_rmap_convert_state);
 
 DECLARE_EVENT_CLASS(xfs_rmapbt_class,
 	TP_PROTO(struct xfs_mount *mp, xfs_agnumber_t agno,
@@ -2553,6 +2557,7 @@ DEFINE_AG_ERROR_EVENT(xfs_rmap_delete_error);
 DEFINE_AG_ERROR_EVENT(xfs_rmap_update_error);
 DEFINE_RMAPBT_EVENT(xfs_rmap_lookup_le_range_result);
 DEFINE_RMAPBT_EVENT(xfs_rmap_find_right_neighbor_result);
+DEFINE_RMAPBT_EVENT(xfs_rmap_find_left_neighbor_result);
 
 #endif /* _TRACE_XFS_H */