--- a/src/os/unix/ngx_writev_chain.c
+++ b/src/os/unix/ngx_writev_chain.c
@@ -13,15 +13,14 @@
 ngx_chain_t *
 ngx_writev_chain(ngx_connection_t *c, ngx_chain_t *in, off_t limit)
 {
-    u_char        *prev;
-    ssize_t        n, size, sent;
+    ssize_t        n, sent;
     off_t          send, prev_send;
     ngx_uint_t     eintr;
     ngx_err_t      err;
-    ngx_array_t    vec;
     ngx_chain_t   *cl;
     ngx_event_t   *wev;
-    struct iovec  *iov, iovs[NGX_IOVS_PREALLOCATE];
+    ngx_iovec_t    vec;
+    struct iovec   iovs[NGX_IOVS_PREALLOCATE];
 
     wev = c->write;
 
@@ -48,61 +47,43 @@ ngx_writev_chain(ngx_connection_t *c, ng
 
     send = 0;
 
-    vec.elts = iovs;
-    vec.size = sizeof(struct iovec);
+    vec.iovs = iovs;
     vec.nalloc = NGX_IOVS_PREALLOCATE;
-    vec.pool = c->pool;
 
     for ( ;; ) {
-        prev = NULL;
-        iov = NULL;
         eintr = 0;
         prev_send = send;
 
-        vec.nelts = 0;
-
         /* create the iovec and coalesce the neighbouring bufs */
 
-        for (cl = in; cl && send < limit; cl = cl->next) {
-
-            if (ngx_buf_special(cl->buf)) {
-                continue;
-            }
-
-#if 1
-            if (!ngx_buf_in_memory(cl->buf)) {
-                ngx_debug_point();
-            }
-#endif
-
-            size = cl->buf->last - cl->buf->pos;
-
-            if (send + size > limit) {
-                size = (ssize_t) (limit - send);
-            }
+        cl = ngx_output_chain_to_iovec(&vec, in, limit - send, c->log);
 
-            if (prev == cl->buf->pos) {
-                iov->iov_len += size;
-
-            } else {
-                if (vec.nelts >= IOV_MAX) {
-                    break;
-                }
-
-                iov = ngx_array_push(&vec);
-                if (iov == NULL) {
-                    return NGX_CHAIN_ERROR;
-                }
-
-                iov->iov_base = (void *) cl->buf->pos;
-                iov->iov_len = size;
-            }
-
-            prev = cl->buf->pos + size;
-            send += size;
+        if (cl == NGX_CHAIN_ERROR) {
+            return NGX_CHAIN_ERROR;
         }
 
-        n = writev(c->fd, vec.elts, vec.nelts);
+        if (cl && cl->buf->in_file) {
+            ngx_log_error(NGX_LOG_ALERT, c->log, 0,
+                          "file buf in writev "
+                          "t:%d r:%d f:%d %p %p-%p %p %O-%O",
+                          cl->buf->temporary,
+                          cl->buf->recycled,
+                          cl->buf->in_file,
+                          cl->buf->start,
+                          cl->buf->pos,
+                          cl->buf->last,
+                          cl->buf->file,
+                          cl->buf->file_pos,
+                          cl->buf->file_last);
+
+            ngx_debug_point();
+
+            return NGX_CHAIN_ERROR;
+        }
+
+        send += vec.size;
+
+        n = writev(c->fd, vec.iovs, vec.count);
 
         if (n == -1) {
             err = ngx_errno;
@@ -148,3 +129,77 @@ ngx_writev_chain(ngx_connection_t *c, ng
         }
     }
 }
+
+
+ngx_chain_t *
+ngx_output_chain_to_iovec(ngx_iovec_t *vec, ngx_chain_t *in, size_t limit,
+    ngx_log_t *log)
+{
+    size_t         total, size;
+    u_char        *prev;
+    ngx_uint_t     n;
+    struct iovec  *iov;
+
+    iov = NULL;
+    prev = NULL;
+    total = 0;
+    n = 0;
+
+    for ( /* void */ ; in && total < limit; in = in->next) {
+
+        if (ngx_buf_special(in->buf)) {
+            continue;
+        }
+
+        if (in->buf->in_file) {
+            break;
+        }
+
+        if (!ngx_buf_in_memory(in->buf)) {
+            ngx_log_error(NGX_LOG_ALERT, log, 0,
+                          "bad buf in output chain "
+                          "t:%d r:%d f:%d %p %p-%p %p %O-%O",
+                          in->buf->temporary,
+                          in->buf->recycled,
+                          in->buf->in_file,
+                          in->buf->start,
+                          in->buf->pos,
+                          in->buf->last,
+                          in->buf->file,
+                          in->buf->file_pos,
+                          in->buf->file_last);
+
+            ngx_debug_point();
+
+            return NGX_CHAIN_ERROR;
+        }
+
+        size = in->buf->last - in->buf->pos;
+
+        if (size > limit - total) {
+            size = limit - total;
+        }
+
+        if (prev == in->buf->pos) {
+            iov->iov_len += size;
+
+        } else {
+            if (n == vec->nalloc) {
+                break;
+            }
+
+            iov = &vec->iovs[n++];
+
+            iov->iov_base = (void *) in->buf->pos;
+            iov->iov_len = size;
+        }
+
+        prev = in->buf->pos + size;
+        total += size;
+    }
+
+    vec->count = n;
+    vec->size = total;
+
+    return in;
+}