Make `zpool import -d|-c` behave consistently

When importing pools with zpool import -aN there is inconsistent
behavior between '-d /dev/disk/by-id' (or another path) and
'-c /etc/zfs/zpool.cache'.

The difference in behavior is caused by zpool_find_import_cached()
returning an empty nvlist_t when there are no pools to import but
zpool_find_import_impl() returns NULL for the same situation. The
behavior of zpool_find_import_cached() is arguably more correct
because it allows returning NULL to be used for an error case and
not an empty set.

This change resolves the issue by updating get_configs() such that
it returns an empty set instead of NULL when no config is found.
The updated behavior will now always return 0 for this case.

$ zpool import -aN; echo $?
no pools available to import
0

$ zpool import -aN -d /var/tmp/; echo $?
no pools available to import
0

$ zpool import -aN -c /etc/zfs/zpool.cache; echo $?
no pools available to import
0

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2080

diff --git a/lib/libzfs/libzfs_import.c b/lib/libzfs/libzfs_import.c
index e71cbb86b2fa0620cbfd3abbac0f26117aee056c..301b08883629c48fef1f8f9c979709666397ce2f 100644 (file)
--- a/lib/libzfs/libzfs_import.c
+++ b/lib/libzfs/libzfs_import.c
@@ -444,7 +444,6 @@ get_configs(libzfs_handle_t *hdl, pool_list_t *pl, boolean_t active_ok)
        boolean_t isactive;
        uint64_t hostid;
        nvlist_t *nvl;
-       boolean_t found_one = B_FALSE;
        boolean_t valid_top_config = B_FALSE;
 
        if (nvlist_alloc(&ret, 0, 0) != 0)
@@ -813,16 +812,10 @@ add_pool:
                if (nvlist_add_nvlist(ret, name, config) != 0)
                        goto nomem;
 
-               found_one = B_TRUE;
                nvlist_free(config);
                config = NULL;
        }
 
-       if (!found_one) {
-               nvlist_free(ret);
-               ret = NULL;
-       }
-
        return (ret);
 
 nomem: