--- a/src/core/ngx_output_chain.c
+++ b/src/core/ngx_output_chain.c
@@ -74,18 +74,18 @@ ngx_output_chain(ngx_output_chain_ctx_t 
         }
     }
 
-#if (NGX_HAVE_FILE_AIO)
-    if (ctx->aio) {
-        return NGX_AGAIN;
-    }
-#endif
-
     out = NULL;
     last_out = &out;
     last = NGX_NONE;
 
     for ( ;; ) {
 
+#if (NGX_HAVE_FILE_AIO)
+        if (ctx->aio) {
+            return NGX_AGAIN;
+        }
+#endif
+
         while (ctx->in) {
 
             /*
@@ -465,10 +465,7 @@ ngx_output_chain_copy_buf(ngx_output_cha
     dst = ctx->buf;
 
     size = ngx_buf_size(src);
-
-    if (size > dst->end - dst->pos) {
-        size = dst->end - dst->pos;
-    }
+    size = ngx_min(size, dst->end - dst->pos);
 
     sendfile = ctx->sendfile & !ctx->directio;
 
@@ -514,7 +511,7 @@ ngx_output_chain_copy_buf(ngx_output_cha
 #if (NGX_HAVE_ALIGNED_DIRECTIO)
 
         if (ctx->unaligned) {
-            if (ngx_directio_off(src->file->fd) == -1) {
+            if (ngx_directio_off(src->file->fd) == NGX_FILE_ERROR) {
                 ngx_log_error(NGX_LOG_ALERT, ctx->pool->log, ngx_errno,
                               ngx_directio_off_n " \"%s\" failed",
                               src->file->name.data);
@@ -550,7 +547,7 @@ ngx_output_chain_copy_buf(ngx_output_cha
 
             err = ngx_errno;
 
-            if (ngx_directio_on(src->file->fd) == -1) {
+            if (ngx_directio_on(src->file->fd) == NGX_FILE_ERROR) {
                 ngx_log_error(NGX_LOG_ALERT, ctx->pool->log, ngx_errno,
                               ngx_directio_on_n " \"%s\" failed",
                               src->file->name.data);