3743 zfs needs a refcount audit
Submitted by:   Will Andrews <willa@spectralogic.com>
Submitted by:   Justin Gibbs <justing@spectralogic.com>
Reviewed by:    Matthew Ahrens <mahrens@delphix.com>
Reviewed by:    Eric Schrock <eric.schrock@delphix.com>
Reviewed by:    George Wilson <george.wilson@delphix.com>

*** 293,302 ****
--- 293,303 ----
                  blk = (idx*2) >> (bs-3);
  
                  err = dmu_buf_hold(zap->zap_objset, zap->zap_object,
                      (tbl->zt_nextblk + blk) << bs, FTAG, &db,
                      DMU_READ_NO_PREFETCH);
+                 if (err == 0)
                          dmu_buf_rele(db, FTAG);
          }
          return (err);
  }
  
*** 990,1061 ****
  {
          zap_cursor_t zc;
          zap_attribute_t za;
          int err;
  
          for (zap_cursor_init(&zc, os, fromobj);
              zap_cursor_retrieve(&zc, &za) == 0;
              (void) zap_cursor_advance(&zc)) {
!                 if (za.za_integer_length != 8 || za.za_num_integers != 1)
!                         return (SET_ERROR(EINVAL));
                  err = zap_add(os, intoobj, za.za_name,
                      8, 1, &za.za_first_integer, tx);
                  if (err)
!                         return (err);
          }
          zap_cursor_fini(&zc);
!         return (0);
  }
  
  int
  zap_join_key(objset_t *os, uint64_t fromobj, uint64_t intoobj,
      uint64_t value, dmu_tx_t *tx)
  {
          zap_cursor_t zc;
          zap_attribute_t za;
          int err;
  
          for (zap_cursor_init(&zc, os, fromobj);
              zap_cursor_retrieve(&zc, &za) == 0;
              (void) zap_cursor_advance(&zc)) {
!                 if (za.za_integer_length != 8 || za.za_num_integers != 1)
!                         return (SET_ERROR(EINVAL));
                  err = zap_add(os, intoobj, za.za_name,
                      8, 1, &value, tx);
                  if (err)
!                         return (err);
          }
          zap_cursor_fini(&zc);
!         return (0);
  }
  
  int
  zap_join_increment(objset_t *os, uint64_t fromobj, uint64_t intoobj,
      dmu_tx_t *tx)
  {
          zap_cursor_t zc;
          zap_attribute_t za;
          int err;
  
          for (zap_cursor_init(&zc, os, fromobj);
              zap_cursor_retrieve(&zc, &za) == 0;
              (void) zap_cursor_advance(&zc)) {
                  uint64_t delta = 0;
  
!                 if (za.za_integer_length != 8 || za.za_num_integers != 1)
!                         return (SET_ERROR(EINVAL));
  
                  err = zap_lookup(os, intoobj, za.za_name, 8, 1, &delta);
                  if (err != 0 && err != ENOENT)
!                         return (err);
                  delta += za.za_first_integer;
                  err = zap_update(os, intoobj, za.za_name, 8, 1, &delta, tx);
                  if (err)
!                         return (err);
          }
          zap_cursor_fini(&zc);
!         return (0);
  }
  
  int
  zap_add_int(objset_t *os, uint64_t obj, uint64_t value, dmu_tx_t *tx)
  {
--- 991,1071 ----
  {
          zap_cursor_t zc;
          zap_attribute_t za;
          int err;
  
+         err = 0;
          for (zap_cursor_init(&zc, os, fromobj);
              zap_cursor_retrieve(&zc, &za) == 0;
              (void) zap_cursor_advance(&zc)) {
!                 if (za.za_integer_length != 8 || za.za_num_integers != 1) {
!                         err = SET_ERROR(EINVAL);
!                         break;
!                 }
                  err = zap_add(os, intoobj, za.za_name,
                      8, 1, &za.za_first_integer, tx);
                  if (err)
!                         break;
          }
          zap_cursor_fini(&zc);
!         return (err);
  }
  
  int
  zap_join_key(objset_t *os, uint64_t fromobj, uint64_t intoobj,
      uint64_t value, dmu_tx_t *tx)
  {
          zap_cursor_t zc;
          zap_attribute_t za;
          int err;
  
+         err = 0;
          for (zap_cursor_init(&zc, os, fromobj);
              zap_cursor_retrieve(&zc, &za) == 0;
              (void) zap_cursor_advance(&zc)) {
!                 if (za.za_integer_length != 8 || za.za_num_integers != 1) {
!                         err = SET_ERROR(EINVAL);
!                         break;
!                 }
                  err = zap_add(os, intoobj, za.za_name,
                      8, 1, &value, tx);
                  if (err)
!                         break;
          }
          zap_cursor_fini(&zc);
!         return (err);
  }
  
  int
  zap_join_increment(objset_t *os, uint64_t fromobj, uint64_t intoobj,
      dmu_tx_t *tx)
  {
          zap_cursor_t zc;
          zap_attribute_t za;
          int err;
  
+         err = 0;
          for (zap_cursor_init(&zc, os, fromobj);
              zap_cursor_retrieve(&zc, &za) == 0;
              (void) zap_cursor_advance(&zc)) {
                  uint64_t delta = 0;
  
!                 if (za.za_integer_length != 8 || za.za_num_integers != 1) {
!                         err = SET_ERROR(EINVAL);
!                         break;
!                 }
  
                  err = zap_lookup(os, intoobj, za.za_name, 8, 1, &delta);
                  if (err != 0 && err != ENOENT)
!                         break;
                  delta += za.za_first_integer;
                  err = zap_update(os, intoobj, za.za_name, 8, 1, &delta, tx);
                  if (err)
!                         break;
          }
          zap_cursor_fini(&zc);
!         return (err);
  }
  
  int
  zap_add_int(objset_t *os, uint64_t obj, uint64_t value, dmu_tx_t *tx)
  {