io_uring: mark having different creds unlikely

Hint the compiler that it's not as likely to have creds different from
current attached to a request. The current code generation is far from
ideal, hopefully it can help to some compilers to remove duplicated jump
tables and so.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/e7815251ac4bf5a4a23d298c752f029ae19f3837.1632516769.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -6638,7 +6638,7 @@ static int io_issue_sqe(struct io_kiocb *req, unsigned int issue_flags)
 	const struct cred *creds = NULL;
 	int ret;
 
-	if ((req->flags & REQ_F_CREDS) && req->creds != current_cred())
+	if (unlikely((req->flags & REQ_F_CREDS) && req->creds != current_cred()))
 		creds = override_creds(req->creds);
 
 	switch (req->opcode) {