uniform ngx_directio_on/off() interface with other file functions
diff --git a/src/core/ngx_open_file_cache.c b/src/core/ngx_open_file_cache.c
index aa87fd2..5f6e0b2 100644
--- a/src/core/ngx_open_file_cache.c
+++ b/src/core/ngx_open_file_cache.c
@@ -525,7 +525,7 @@
         of->fd = fd;
 
         if (of->directio <= ngx_file_size(&fi)) {
-            if (ngx_directio_on(fd) == -1) {
+            if (ngx_directio_on(fd) == NGX_FILE_ERROR) {
                 ngx_log_error(NGX_LOG_ALERT, log, ngx_errno,
                               ngx_directio_on_n " \"%s\" failed", name);