5814 bpobj_iterate_impl(): Close a refcount leak iterating on a sublist.

Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Paul Dagnelie <paul.dagnelie@delphix.com>
Reviewed by: Simon Klinkert <simon.klinkert@gmail.com>
Approved by: Gordon Ross <gwr@nexenta.com>

usr/src/uts/common/fs/zfs/bpobj.c

@@ -300,8 +300,10 @@ bpobj_iterate_impl(bpobj_t *bpo, bpobj_itor_t func, void *arg, dmu_tx_t *tx,
 		if (free) {
 			err = bpobj_space(&sublist,
 			    &used_before, &comp_before, &uncomp_before);
-			if (err)
+			if (err != 0) {
+				bpobj_close(&sublist);
 				break;
+			}
 		}
 		err = bpobj_iterate_impl(&sublist, func, arg, tx, free);
 		if (free) {