krwlock_t z_teardown_inactive_lock;
list_t z_all_znodes; /* all znodes in the fs */
uint64_t z_nr_znodes; /* number of znodes in the fs */
+ unsigned long z_rollback_time;/* last online rollback time */
kmutex_t z_znodes_lock; /* lock for z_all_znodes */
struct inode *z_ctldir; /* .zfs directory inode */
avl_tree_t z_ctldir_snaps; /* .zfs/snapshot entries */