DEFINE_PNFS_LAYOUT_EVENT
DEFINE_PNFS_LAYOUT_EVENT(pnfs_mds_fallback_pg_init_read);
DEFINE_PNFS_LAYOUT_EVENT(pnfs_mds_fallback_pg_init_write);
DEFINE_PNFS_LAYOUT_EVENT(pnfs_mds_fallback_pg_get_mirror_count);
DEFINE_PNFS_LAYOUT_EVENT(pnfs_mds_fallback_read_done);
DEFINE_PNFS_LAYOUT_EVENT(pnfs_mds_fallback_write_done);
DEFINE_PNFS_LAYOUT_EVENT(pnfs_mds_fallback_read_pagelist);
DEFINE_PNFS_LAYOUT_EVENT(pnfs_mds_fallback_write_pagelist);