1 files changed, 11 insertions, 0 deletions
diff --git a/src/os/unix/ngx_linux_sendfile_chain.c b/src/os/unix/ngx_linux_sendfile_chain.c
index 97f741d0a..9f272225a 100644
--- a/src/os/unix/ngx_linux_sendfile_chain.c
+++ b/src/os/unix/ngx_linux_sendfile_chain.c
@@ -354,6 +354,17 @@ ngx_linux_sendfile_thread(ngx_connection_t *c, ngx_buf_t *file, size_t size,
         return (ctx->sent == ctx->size) ? NGX_DONE : NGX_AGAIN;
     }
 
+    if (task->event.active && ctx->file == file) {
+        /*
+         * tolerate duplicate calls; they can happen due to subrequests
+         * or multiple calls of the next body filter from a filter
+         */
+
+        *sent = 0;
+
+        return NGX_OK;
+    }
+
     ctx->file = file;
     ctx->socket = c->fd;
     ctx->size = size;