spin_unlock(&session->s_cap_lock);
/* trim unused caps to reduce MDS's cache rejoin time */
- shrink_dcache_parent(mdsc->fsc->sb->s_root);
+ if (mdsc->fsc->sb->s_root)
+ shrink_dcache_parent(mdsc->fsc->sb->s_root);
ceph_con_close(&session->s_con);
ceph_con_open(&session->s_con,