5269 zfs: zpool import slow
PORTING: this code relies on the property of taskq_wait to wait
until no more tasks are queued and no more tasks are active. As
we always queue new tasks from within other tasks, task_wait
reliably waits for the full recursion to finish, even though we
enqueue new tasks after taskq_wait has been called.
On platforms other than illumos, taskq_wait may not have this
property.
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Dan McDonald <danmcd@omniti.com>
Reviewed by: George Wilson <george.wilson@delphix.com>

*** 1736,1752 ****
   */
  static boolean_t
  spa_check_logs(spa_t *spa)
  {
          boolean_t rv = B_FALSE;
  
          switch (spa->spa_log_state) {
          case SPA_LOG_MISSING:
                  /* need to recheck in case slog has been restored */
          case SPA_LOG_UNKNOWN:
!                 rv = (dmu_objset_find(spa->spa_name, zil_check_log_chain,
!                     NULL, DS_FIND_CHILDREN) != 0);
                  if (rv)
                          spa_set_log_state(spa, SPA_LOG_MISSING);
                  break;
          }
          return (rv);
--- 1736,1753 ----
   */
  static boolean_t
  spa_check_logs(spa_t *spa)
  {
          boolean_t rv = B_FALSE;
+         dsl_pool_t *dp = spa_get_dsl(spa);
  
          switch (spa->spa_log_state) {
          case SPA_LOG_MISSING:
                  /* need to recheck in case slog has been restored */
          case SPA_LOG_UNKNOWN:
!                 rv = (dmu_objset_find_dp(dp, dp->dp_root_dir_obj,
!                     zil_check_log_chain, NULL, DS_FIND_CHILDREN) != 0);
                  if (rv)
                          spa_set_log_state(spa, SPA_LOG_MISSING);
                  break;
          }
          return (rv);
*** 2713,2722 ****
--- 2714,2724 ----
  
          if (spa_writeable(spa) && (state == SPA_LOAD_RECOVER ||
              spa->spa_load_max_txg == UINT64_MAX)) {
                  dmu_tx_t *tx;
                  int need_update = B_FALSE;
+                 dsl_pool_t *dp = spa_get_dsl(spa);
  
                  ASSERT(state != SPA_LOAD_TRYIMPORT);
  
                  /*
                   * Claim log blocks that haven't been committed yet.
*** 2725,2737 ****
                   * invoked from zil_claim_log_block()'s i/o done callback.
                   * Price of rollback is that we abandon the log.
                   */
                  spa->spa_claiming = B_TRUE;
  
!                 tx = dmu_tx_create_assigned(spa_get_dsl(spa),
!                     spa_first_txg(spa));
!                 (void) dmu_objset_find(spa_name(spa),
                      zil_claim, tx, DS_FIND_CHILDREN);
                  dmu_tx_commit(tx);
  
                  spa->spa_claiming = B_FALSE;
  
--- 2727,2738 ----
                   * invoked from zil_claim_log_block()'s i/o done callback.
                   * Price of rollback is that we abandon the log.
                   */
                  spa->spa_claiming = B_TRUE;
  
!                 tx = dmu_tx_create_assigned(dp, spa_first_txg(spa));
!                 (void) dmu_objset_find_dp(dp, dp->dp_root_dir_obj,
                      zil_claim, tx, DS_FIND_CHILDREN);
                  dmu_tx_commit(tx);
  
                  spa->spa_claiming = B_FALSE;