diff --git a/src/os/unix/ngx_files.c b/src/os/unix/ngx_files.c
index ab86146..661ecaa 100644
--- a/src/os/unix/ngx_files.c
+++ b/src/os/unix/ngx_files.c
@@ -389,7 +389,7 @@
 #if (NGX_HAVE_O_DIRECT)
 
 ngx_int_t
-ngx_directio(ngx_fd_t fd)
+ngx_directio_on(ngx_fd_t fd)
 {
     int  flags;
 
@@ -402,4 +402,19 @@
     return fcntl(fd, F_SETFL, flags | O_DIRECT);
 }
 
+
+ngx_int_t
+ngx_directio_off(ngx_fd_t fd)
+{
+    int  flags;
+
+    flags = fcntl(fd, F_GETFL);
+
+    if (flags == -1) {
+        return -1;
+    }
+
+    return fcntl(fd, F_SETFL, flags & ~O_DIRECT);
+}
+
 #endif
diff --git a/src/os/unix/ngx_files.h b/src/os/unix/ngx_files.h
index 9988bcc..d7a38d9 100644
--- a/src/os/unix/ngx_files.h
+++ b/src/os/unix/ngx_files.h
@@ -222,23 +222,26 @@
 
 #if (NGX_HAVE_O_DIRECT)
 
-ngx_int_t ngx_directio(ngx_fd_t fd);
-#define ngx_directio_n           "fcntl(O_DIRECT)"
+ngx_int_t ngx_directio_on(ngx_fd_t fd);
+#define ngx_directio_on_n        "fcntl(O_DIRECT)"
+
+ngx_int_t ngx_directio_off(ngx_fd_t fd);
+#define ngx_directio_off_n       "fcntl(!O_DIRECT)"
 
 #elif (NGX_HAVE_F_NOCACHE)
 
-#define ngx_directio(fd)         fcntl(fd, F_NOCACHE, 1)
-#define ngx_directio_n           "fcntl(F_NOCACHE)"
+#define ngx_directio_on(fd)      fcntl(fd, F_NOCACHE, 1)
+#define ngx_directio_on_n        "fcntl(F_NOCACHE, 1)"
 
 #elif (NGX_HAVE_DIRECTIO)
 
-#define ngx_directio(fd)         directio(fd, DIRECTIO_ON)
-#define ngx_directio_n           "directio(DIRECTIO_ON)"
+#define ngx_directio_on(fd)      directio(fd, DIRECTIO_ON)
+#define ngx_directio_on_n        "directio(DIRECTIO_ON)"
 
 #else
 
-#define ngx_directio(fd)         0
-#define ngx_directio_n           "ngx_directio_n"
+#define ngx_directio_on(fd)      0
+#define ngx_directio_on_n        "ngx_directio_on_n"
 
 #endif