io_uring: fix overflowed reqs cancellation

Overflowed requests in io_uring_cancel_files() should be shed only of
inflight and overflowed refs. All other left references are owned by
someone else.

If refcount_sub_and_test() fails, it will go further and put put extra
ref, don't do that. Also, don't need to do io_wq_cancel_work()
for overflowed reqs, they will be let go shortly anyway.

Signed-off-by: Pavel Begunkov <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

Author: isilence

fs/io_uring.c

@@ -7449,10 +7449,11 @@ static void io_uring_cancel_files(struct io_ring_ctx *ctx,
 				finish_wait(&ctx->inflight_wait, &wait);
 				continue;
 			}
+		} else {
+			io_wq_cancel_work(ctx->io_wq, &cancel_req->work);
+			io_put_req(cancel_req);
 		}
 
-		io_wq_cancel_work(ctx->io_wq, &cancel_req->work);
-		io_put_req(cancel_req);
 		schedule();
 		finish_wait(&ctx->inflight_wait, &wait);
 	}