new file mode 100644
--- /dev/null
+++ b/src/os/unix/ngx_file_aio_read.c
@@ -0,0 +1,210 @@
+
+/*
+ * Copyright (C) Igor Sysoev
+ */
+
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+#include <ngx_event.h>
+
+
+/*
+ * FreeBSD file AIO features and quirks:
+ *
+ *    if an asked data are already in VM cache, then aio_error() returns 0,
+ *    and the data are already copied in buffer;
+ *
+ *    aio_read() preread in VM cache as minimum 32K;
+ *
+ *    aio_read/aio_error() may return EINPROGRESS for just written data;
+ *
+ *    kqueue EVFILT_AIO filter is level triggered only: an event repeats
+ *    until aio_return() will be called;
+ *
+ *    aio_cancel() can not cancel file AIO: it returns AIO_NOTCANCELED always.
+ */
+
+
+extern int  ngx_kqueue;
+
+
+static ssize_t ngx_file_aio_result(ngx_file_t *file, ngx_event_aio_t *aio,
+    ngx_event_t *ev);
+static void ngx_file_aio_event_handler(ngx_event_t *ev);
+
+
+ssize_t
+ngx_file_aio_read(ngx_file_t *file, u_char *buf, size_t size, off_t offset,
+    ngx_pool_t *pool)
+{
+    int                 n;
+    ngx_event_t        *ev;
+    ngx_event_aio_t    *aio;
+    static ngx_uint_t   enosys = 0;
+
+    if (enosys) {
+        return ngx_read_file(file, buf, size, offset);
+    }
+
+    aio = file->aio;
+
+    if (aio == NULL) {
+        aio = ngx_pcalloc(pool, sizeof(ngx_event_aio_t));
+        if (aio == NULL) {
+            return NGX_ERROR;
+        }
+
+        aio->file = file;
+        aio->fd = file->fd;
+        aio->event.data = aio;
+        aio->event.ready = 1;
+        aio->event.log = file->log;
+        file->aio = aio;
+    }
+
+    ev = &aio->event;
+
+    if (!ev->ready) {
+        ngx_log_error(NGX_LOG_ALERT, file->log, 0,
+                      "second aio post for \"%V\"", &file->name);
+        return NGX_AGAIN;
+    }
+
+    ngx_log_debug4(NGX_LOG_DEBUG_CORE, file->log, 0,
+                   "aio complete:%d @%O:%z %V",
+                   ev->complete, offset, size, &file->name);
+
+    if (ev->complete) {
+        ev->complete = 0;
+        ngx_set_errno(aio->err);
+
+        if (aio->err == 0) {
+            return aio->nbytes;
+        }
+
+        return NGX_ERROR;
+    }
+
+    ngx_memzero(&aio->aiocb, sizeof(struct aiocb));
+
+    aio->aiocb.aio_fildes = file->fd;
+    aio->aiocb.aio_offset = offset;
+    aio->aiocb.aio_buf = buf;
+    aio->aiocb.aio_nbytes = size;
+#if (NGX_HAVE_KQUEUE)
+    aio->aiocb.aio_sigevent.sigev_notify_kqueue = ngx_kqueue;
+    aio->aiocb.aio_sigevent.sigev_notify = SIGEV_KEVENT;
+    aio->aiocb.aio_sigevent.sigev_value.sigval_ptr = ev;
+#endif
+    ev->handler = ngx_file_aio_event_handler;
+
+    n = aio_read(&aio->aiocb);
+
+    if (n == -1) {
+        n = ngx_errno;
+
+        if (n == NGX_EAGAIN) {
+            return ngx_read_file(file, buf, size, offset);
+        }
+
+        ngx_log_error(NGX_LOG_CRIT, file->log, n,
+                      "aio_read(\"%V\") failed", &file->name);
+
+        if (n == NGX_ENOSYS) {
+            enosys = 1;
+            return ngx_read_file(file, buf, size, offset);
+        }
+
+        return NGX_ERROR;
+    }
+
+    ngx_log_debug2(NGX_LOG_DEBUG_CORE, file->log, 0,
+                   "aio_read: fd:%d %d", file->fd, n);
+
+    ev->active = 1;
+    ev->ready = 0;
+    ev->complete = 0;
+
+    return ngx_file_aio_result(aio->file, aio, ev);
+}
+
+
+static ssize_t
+ngx_file_aio_result(ngx_file_t *file, ngx_event_aio_t *aio, ngx_event_t *ev)
+{
+    int        n;
+    ngx_err_t  err;
+
+    n = aio_error(&aio->aiocb);
+
+    ngx_log_debug2(NGX_LOG_DEBUG_CORE, file->log, 0,
+                   "aio_error: fd:%d %d", file->fd, n);
+
+    if (n == -1) {
+        err = ngx_errno;
+        aio->err = err;
+
+        ngx_log_error(NGX_LOG_ALERT, file->log, err,
+                      "aio_error(\"%V\") failed", &file->name);
+        return NGX_ERROR;
+    }
+
+    if (n != 0) {
+        if (n == NGX_EINPROGRESS) {
+            if (ev->ready) {
+                ev->ready = 0;
+                ngx_log_error(NGX_LOG_ALERT, file->log, n,
+                              "aio_read(\"%V\") still in progress",
+                              &file->name);
+            }
+
+            return NGX_AGAIN;
+        }
+
+        aio->err = n;
+        ev->ready = 0;
+
+        ngx_log_error(NGX_LOG_CRIT, file->log, n,
+                      "aio_read(\"%V\") failed", &file->name);
+        return NGX_ERROR;
+    }
+
+    n = aio_return(&aio->aiocb);
+
+    if (n == -1) {
+        err = ngx_errno;
+        aio->err = err;
+        ev->ready = 0;
+
+        ngx_log_error(NGX_LOG_ALERT, file->log, err,
+                      "aio_return(\"%V\") failed", &file->name);
+        return NGX_ERROR;
+    }
+
+    aio->err = 0;
+    aio->nbytes = n;
+    ev->ready = 1;
+    ev->active = 0;
+
+    ngx_log_debug2(NGX_LOG_DEBUG_CORE, file->log, 0,
+                   "aio_return: fd:%d %d", file->fd, n);
+
+    return n;
+}
+
+
+static void
+ngx_file_aio_event_handler(ngx_event_t *ev)
+{
+    ngx_event_aio_t  *aio;
+
+    aio = ev->data;
+
+    ngx_log_debug2(NGX_LOG_DEBUG_CORE, ev->log, 0,
+                   "aio event handler fd:%d %V", aio->fd, &aio->file->name);
+
+    if (ngx_file_aio_result(aio->file, aio, ev) != NGX_AGAIN) {
+        aio->handler(ev);
+    }
+}