io_uring: refactor io_openat2()

Put do_filp_open() fail path of io_openat2() under a single if,
deduplicating put_unused_fd(), making it look better and helping
the hot path.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/f4c84d25c049d0af2adc19c703bbfef607200209.1624543113.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -3851,27 +3851,26 @@ static int io_openat2(struct io_kiocb *req, unsigned int issue_flags)
 		goto err;
 
 	file = do_filp_open(req->open.dfd, req->open.filename, &op);
-	/* only retry if RESOLVE_CACHED wasn't already set by application */
-	if ((!resolve_nonblock && (issue_flags & IO_URING_F_NONBLOCK)) &&
-	    file == ERR_PTR(-EAGAIN)) {
+	if (IS_ERR(file)) {
 		/*
-		 * We could hang on to this 'fd', but seems like marginal
-		 * gain for something that is now known to be a slower path.
-		 * So just put it, and we'll get a new one when we retry.
+		 * We could hang on to this 'fd' on retrying, but seems like
+		 * marginal gain for something that is now known to be a slower
+		 * path. So just put it, and we'll get a new one when we retry.
 		 */
 		put_unused_fd(ret);
+
+		ret = PTR_ERR(file);
+		/* only retry if RESOLVE_CACHED wasn't already set by application */
+		if (ret == -EAGAIN &&
+		    (!resolve_nonblock && (issue_flags & IO_URING_F_NONBLOCK)))
 			return -EAGAIN;
+		goto err;
 	}
 
-	if (IS_ERR(file)) {
-		put_unused_fd(ret);
-		ret = PTR_ERR(file);
-	} else {
 	if ((issue_flags & IO_URING_F_NONBLOCK) && !nonblock_set)
 		file->f_flags &= ~O_NONBLOCK;
 	fsnotify_open(file);
 	fd_install(ret, file);
-	}
 err:
 	putname(req->open.filename);
 	req->flags &= ~REQ_F_NEED_CLEANUP;