Threads: task pointer stored in ngx_file_t. This simplifies the interface of the ngx_thread_read() function. Additionally, most of the thread operations now explicitly set file->thread_task, file->thread_handler and file->thread_ctx, to facilitate use of thread operations in other places. (Potential problems remain with sendfile in threads though - it uses file->thread_handler as set in ngx_output_chain(), and it should not be overwritten to an incompatible one.) In collaboration with Valentin Bartenev.

--- a/src/os/unix/ngx_files.h
+++ b/src/os/unix/ngx_files.h
@@ -385,8 +385,8 @@ extern ngx_uint_t  ngx_file_aio;
 #endif
 
 #if (NGX_THREADS)
-ssize_t ngx_thread_read(ngx_thread_task_t **taskp, ngx_file_t *file,
-    u_char *buf, size_t size, off_t offset, ngx_pool_t *pool);
+ssize_t ngx_thread_read(ngx_file_t *file, u_char *buf, size_t size,
+    off_t offset, ngx_pool_t *pool);
 #endif