1693 persistent 'comment' field for a zpool

@@ -18,10 +18,12 @@
  *
  * CDDL HEADER END
  */
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
+ * Copyright (c) 2011 by Delphix. All rights reserved.
  */
 
 /*
  * Pool import support functions.
  *

@@ -435,11 +437,11 @@
         nvlist_t *ret = NULL, *config = NULL, *tmp, *nvtop, *nvroot;
         nvlist_t **spares, **l2cache;
         uint_t i, nspares, nl2cache;
         boolean_t config_seen;
         uint64_t best_txg;
-        char *name, *hostname;
+        char *name, *hostname, *comment;
         uint64_t version, guid;
         uint_t children = 0;
         nvlist_t **child = NULL;
         uint_t holes;
         uint64_t *hole_array, max_id;

@@ -524,10 +526,11 @@
                                  * configuration:
                                  *
                                  *      version
                                  *      pool guid
                                  *      name
+                                 *      comment (if available)
                                  *      pool state
                                  *      hostid (if available)
                                  *      hostname (if available)
                                  */
                                 uint64_t state;

@@ -545,15 +548,28 @@
                                 verify(nvlist_lookup_string(tmp,
                                     ZPOOL_CONFIG_POOL_NAME, &name) == 0);
                                 if (nvlist_add_string(config,
                                     ZPOOL_CONFIG_POOL_NAME, name) != 0)
                                         goto nomem;
+
+                                /*
+                                 * COMMENT is optional, don't bail if it's not
+                                 * there, instead, set it to NULL.
+                                 */
+                                if (nvlist_lookup_string(tmp,
+                                    ZPOOL_CONFIG_COMMENT, &comment) != 0)
+                                        comment = NULL;
+                                else if (nvlist_add_string(config,
+                                    ZPOOL_CONFIG_COMMENT, comment) != 0)
+                                        goto nomem;
+
                                 verify(nvlist_lookup_uint64(tmp,
                                     ZPOOL_CONFIG_POOL_STATE, &state) == 0);
                                 if (nvlist_add_uint64(config,
                                     ZPOOL_CONFIG_POOL_STATE, state) != 0)
                                         goto nomem;
+
                                 hostid = 0;
                                 if (nvlist_lookup_uint64(tmp,
                                     ZPOOL_CONFIG_HOSTID, &hostid) == 0) {
                                         if (nvlist_add_uint64(config,
                                             ZPOOL_CONFIG_HOSTID, hostid) != 0)