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>

*** 206,215 ****
--- 206,216 ----
  {
          spa_config_dirent_t *dp, *tdp;
          nvlist_t *nvl;
          boolean_t ccw_failure;
          int error;
+         char *pool_name;
  
          ASSERT(MUTEX_HELD(&spa_namespace_lock));
  
          if (rootdir == NULL || !(spa_mode_global & FWRITE))
                  return;
*** 252,262 ****
                          }
  
                          if (nvl == NULL)
                                  nvl = fnvlist_alloc();
  
!                         fnvlist_add_nvlist(nvl, spa->spa_name,
                              spa->spa_config);
                          mutex_exit(&spa->spa_props_lock);
                  }
  
                  error = spa_config_write(dp, nvl);
--- 253,270 ----
                          }
  
                          if (nvl == NULL)
                                  nvl = fnvlist_alloc();
  
!                         if (spa->spa_import_flags & ZFS_IMPORT_TEMP_NAME) {
!                                 pool_name = fnvlist_lookup_string(
!                                     spa->spa_config, ZPOOL_CONFIG_POOL_NAME);
!                         } else {
!                                 pool_name = spa_name(spa);
!                         }
! 
!                         fnvlist_add_nvlist(nvl, pool_name,
                              spa->spa_config);
                          mutex_exit(&spa->spa_props_lock);
                  }
  
                  error = spa_config_write(dp, nvl);
*** 357,366 ****
--- 365,375 ----
          nvlist_t *config, *nvroot;
          vdev_t *rvd = spa->spa_root_vdev;
          unsigned long hostid = 0;
          boolean_t locked = B_FALSE;
          uint64_t split_guid;
+         char *pool_name;
  
          if (vd == NULL) {
                  vd = rvd;
                  locked = B_TRUE;
                  spa_config_enter(spa, SCL_CONFIG | SCL_STATE, FTAG, RW_READER);
*** 373,386 ****
           * If txg is -1, report the current value of spa->spa_config_txg.
           */
          if (txg == -1ULL)
                  txg = spa->spa_config_txg;
  
          config = fnvlist_alloc();
  
          fnvlist_add_uint64(config, ZPOOL_CONFIG_VERSION, spa_version(spa));
!         fnvlist_add_string(config, ZPOOL_CONFIG_POOL_NAME, spa_name(spa));
          fnvlist_add_uint64(config, ZPOOL_CONFIG_POOL_STATE, spa_state(spa));
          fnvlist_add_uint64(config, ZPOOL_CONFIG_POOL_TXG, txg);
          fnvlist_add_uint64(config, ZPOOL_CONFIG_POOL_GUID, spa_guid(spa));
          if (spa->spa_comment != NULL) {
                  fnvlist_add_string(config, ZPOOL_CONFIG_COMMENT,
--- 382,412 ----
           * If txg is -1, report the current value of spa->spa_config_txg.
           */
          if (txg == -1ULL)
                  txg = spa->spa_config_txg;
  
+         /*
+          * Originally, users had to handle spa namespace collisions by either
+          * exporting the already imported pool or by specifying a new name for
+          * the pool with a conflicting name. In the case of root pools from
+          * virtual guests, neither approach to collision resolution is
+          * reasonable. This is addressed by extending the new name syntax with
+          * an option to specify that the new name is temporary. When specified,
+          * ZFS_IMPORT_TEMP_NAME will be set in spa->spa_import_flags to tell us
+          * to use the previous name, which we do below.
+          */
+         if (spa->spa_import_flags & ZFS_IMPORT_TEMP_NAME) {
+                 pool_name = fnvlist_lookup_string(spa->spa_config,
+                     ZPOOL_CONFIG_POOL_NAME);
+         } else {
+                 pool_name = spa_name(spa);
+         }
+ 
          config = fnvlist_alloc();
  
          fnvlist_add_uint64(config, ZPOOL_CONFIG_VERSION, spa_version(spa));
!         fnvlist_add_string(config, ZPOOL_CONFIG_POOL_NAME, pool_name);
          fnvlist_add_uint64(config, ZPOOL_CONFIG_POOL_STATE, spa_state(spa));
          fnvlist_add_uint64(config, ZPOOL_CONFIG_POOL_TXG, txg);
          fnvlist_add_uint64(config, ZPOOL_CONFIG_POOL_GUID, spa_guid(spa));
          if (spa->spa_comment != NULL) {
                  fnvlist_add_string(config, ZPOOL_CONFIG_COMMENT,