5882 Temporary pool names
Reviewed by: Matt Ahrens <matt@delphix.com>
Reviewed by: Igor Kozhukhov <igor@dilos.org>
Reviewed by: John Kennedy <john.kennedy@delphix.com>
Approved by: Dan McDonald <danmcd@joyent.com>

*** 4581,4615 ****
          uint64_t txg = TXG_INITIAL;
          nvlist_t **spares, **l2cache;
          uint_t nspares, nl2cache;
          uint64_t version, obj;
          boolean_t has_features;
  
          /*
           * If this pool already exists, return failure.
           */
          mutex_enter(&spa_namespace_lock);
!         if (spa_lookup(pool) != NULL) {
                  mutex_exit(&spa_namespace_lock);
                  return (SET_ERROR(EEXIST));
          }
  
          /*
           * Allocate a new spa_t structure.
           */
          (void) nvlist_lookup_string(props,
              zpool_prop_to_name(ZPOOL_PROP_ALTROOT), &altroot);
!         spa = spa_add(pool, NULL, altroot);
          spa_activate(spa, spa_mode_global);
  
          if (props && (error = spa_prop_validate(spa, props))) {
                  spa_deactivate(spa);
                  spa_remove(spa);
                  mutex_exit(&spa_namespace_lock);
                  return (error);
          }
  
          has_features = B_FALSE;
          for (nvpair_t *elem = nvlist_next_nvpair(props, NULL);
              elem != NULL; elem = nvlist_next_nvpair(props, elem)) {
                  if (zpool_prop_feature(nvpair_name(elem)))
                          has_features = B_TRUE;
--- 4581,4630 ----
          uint64_t txg = TXG_INITIAL;
          nvlist_t **spares, **l2cache;
          uint_t nspares, nl2cache;
          uint64_t version, obj;
          boolean_t has_features;
+         char *poolname;
+         nvlist_t *nvl;
  
+         if (nvlist_lookup_string(props,
+             zpool_prop_to_name(ZPOOL_PROP_TNAME), &poolname) != 0)
+                 poolname = (char *)pool;
+ 
          /*
           * If this pool already exists, return failure.
           */
          mutex_enter(&spa_namespace_lock);
!         if (spa_lookup(poolname) != NULL) {
                  mutex_exit(&spa_namespace_lock);
                  return (SET_ERROR(EEXIST));
          }
  
          /*
           * Allocate a new spa_t structure.
           */
+         nvl = fnvlist_alloc();
+         fnvlist_add_string(nvl, ZPOOL_CONFIG_POOL_NAME, pool);
          (void) nvlist_lookup_string(props,
              zpool_prop_to_name(ZPOOL_PROP_ALTROOT), &altroot);
!         spa = spa_add(poolname, nvl, altroot);
!         fnvlist_free(nvl);
          spa_activate(spa, spa_mode_global);
  
          if (props && (error = spa_prop_validate(spa, props))) {
                  spa_deactivate(spa);
                  spa_remove(spa);
                  mutex_exit(&spa_namespace_lock);
                  return (error);
          }
  
+         /*
+          * Temporary pool names should never be written to disk.
+          */
+         if (poolname != pool)
+                 spa->spa_import_flags |= ZFS_IMPORT_TEMP_NAME;
+ 
          has_features = B_FALSE;
          for (nvpair_t *elem = nvlist_next_nvpair(props, NULL);
              elem != NULL; elem = nvlist_next_nvpair(props, elem)) {
                  if (zpool_prop_feature(nvpair_name(elem)))
                          has_features = B_TRUE;