fail_path
pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
fail_path(pgpath);
fail_path(pgpath);
fail_path(pgpath);
fail_path(pgpath);
fail_path(pgpath);
action = fail_path;
fail_path(pgpath);
void (*fail_path)(struct path_selector *ps, struct dm_path *p);
.fail_path = hst_fail_path,
.fail_path = ioa_fail_path,
.fail_path = ql_fail_path,
.fail_path = rr_fail_path,
.fail_path = st_fail_path,