static void
 xlog_grant_add_space_write(struct log *log, int bytes)
 {
-       log->l_grant_write_bytes += bytes;
-       if (log->l_grant_write_bytes > log->l_logsize) {
-               log->l_grant_write_bytes -= log->l_logsize;
+       int tmp = log->l_logsize - log->l_grant_write_bytes;
+       if (tmp > bytes)
+               log->l_grant_write_bytes += bytes;
+       else {
                log->l_grant_write_cycle++;
+               log->l_grant_write_bytes = bytes - tmp;
        }
 }
 
 static void
 xlog_grant_add_space_reserve(struct log *log, int bytes)
 {
-       log->l_grant_reserve_bytes += bytes;
-       if (log->l_grant_reserve_bytes > log->l_logsize) {
-               log->l_grant_reserve_bytes -= log->l_logsize;
+       int tmp = log->l_logsize - log->l_grant_reserve_bytes;
+       if (tmp > bytes)
+               log->l_grant_reserve_bytes += bytes;
+       else {
                log->l_grant_reserve_cycle++;
+               log->l_grant_reserve_bytes = bytes - tmp;
        }
 }