io-wq: ensure work->task_pid is cleared on init

We use ->task_pid for exit cancellation, but we need to ensure it's
cleared to zero for io_req_work_grab_env() to do the right thing. Take
a suggestion from Bart and clear the whole thing, just setting the
function passed in. This makes it more future proof as well.

Fixes: 36282881 ("io-wq: add io_wq_cancel_pid() to cancel based on a specific pid")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/io-wq.h

@@ -81,13 +81,7 @@ struct io_wq_work {
 
 #define INIT_IO_WORK(work, _func)				\
 	do {							\
-		(work)->list.next = NULL;		\
-		(work)->func = _func;			\
-		(work)->files = NULL;			\
-		(work)->mm = NULL;			\
-		(work)->creds = NULL;			\
-		(work)->fs = NULL;			\
-		(work)->flags = 0;			\
+		*(work) = (struct io_wq_work){ .func = _func };	\
 	} while (0)						\
 
 typedef void (get_work_fn)(struct io_wq_work *);