Try a ps_end_io_fn
--- diff/drivers/md/dm-mpath.c	2004-11-10 15:12:55.000000000 +0000
+++ source/drivers/md/dm-mpath.c	2004-11-10 15:13:17.000000000 +0000
@@ -957,9 +957,13 @@
 {
 	struct multipath *m = (struct multipath *) ti->private;
 	struct mpath_io *mpio = (struct mpath_io *) map_context->ptr;
+	struct pgpath *pgpath = mpio->pgpath;
+	struct path_selector *ps = &pgpath->pg->ps;
 	int r;
 
 	r  = do_end_io(m, bio, error, mpio);
+	if (ps->type->end_io)
+		ps->type->end_io(ps, &pgpath->path);
 	if (r <= 0)
 		mempool_free(mpio, m->mpio_pool);
 
--- diff/drivers/md/dm-path-selector.h	2004-11-10 15:08:19.000000000 +0000
+++ source/drivers/md/dm-path-selector.h	2004-11-10 15:13:17.000000000 +0000
@@ -71,6 +71,8 @@
 			     status_type_t type,
 			     char *result, unsigned int maxlen);
 
+typedef int (*ps_end_io_fn) (struct path_selector *ps, struct path *path);
+
 /* Information about a path selector type */
 struct path_selector_type {
 	char *name;
@@ -86,6 +88,7 @@
 	ps_reinstate_path_fn reinstate_path;
 	ps_select_path_fn select_path;
 	ps_status_fn status;
+	ps_end_io_fn end_io;
 };
 
 /* Register a path selector */