3752 want more verifiable dbuf user eviction
Submitted by:   Justin Gibbs <justing@spectralogic.com>
Submitted by:   Will Andrews <willa@spectralogic.com>

*** 519,529 ****
  zap_leaf(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
  {
          char buf[16*1024];
          int verbose = B_FALSE;
          int four = B_FALSE;
!         zap_leaf_t l;
          zap_leaf_phys_t *zlp = (void *)buf;
          int i;
  
          if (mdb_getopts(argc, argv,
              'v', MDB_OPT_SETBITS, TRUE, &verbose,
--- 519,529 ----
  zap_leaf(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
  {
          char buf[16*1024];
          int verbose = B_FALSE;
          int four = B_FALSE;
!         zap_leaf_t l = { 0 };
          zap_leaf_phys_t *zlp = (void *)buf;
          int i;
  
          if (mdb_getopts(argc, argv,
              'v', MDB_OPT_SETBITS, TRUE, &verbose,
*** 1423,1434 ****
  typedef struct mdb_spa {
          uintptr_t spa_dsl_pool;
          uintptr_t spa_root_vdev;
  } mdb_spa_t;
  
  typedef struct mdb_dsl_dir {
!         uintptr_t dd_phys;
          int64_t dd_space_towrite[TXG_SIZE];
  } mdb_dsl_dir_t;
  
  typedef struct mdb_dsl_dir_phys {
          uint64_t dd_used_bytes;
--- 1423,1443 ----
  typedef struct mdb_spa {
          uintptr_t spa_dsl_pool;
          uintptr_t spa_root_vdev;
  } mdb_spa_t;
  
+ struct mdb_dsl_dir_phys;
+ typedef struct mdb_dsl_dir_dbuf {
+         uint8_t dddb_pad[offsetof(dmu_buf_t, db_data)];
+         uintptr_t dddb_data;
+ } mdb_dsl_dir_dbuf_t;
+ 
  typedef struct mdb_dsl_dir {
!         union {
!                 dmu_buf_t *dd_dmu_db;
!                 mdb_dsl_dir_dbuf_t *dd_db;
!         } dd_db_u;
          int64_t dd_space_towrite[TXG_SIZE];
  } mdb_dsl_dir_t;
  
  typedef struct mdb_dsl_dir_phys {
          uint64_t dd_used_bytes;