io_uring: update sqe layout build checks

Add missing BUILD_BUG_SQE_ELEM() for ->buf_group verifying that SQE
layout doesn't change.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/1f9d21bd74599b856b3a632be4c23ffa184a3ef0.1624543113.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -10267,6 +10267,7 @@ static int __init io_uring_init(void)
 	BUILD_BUG_SQE_ELEM(28, __u32,  splice_flags);
 	BUILD_BUG_SQE_ELEM(32, __u64,  user_data);
 	BUILD_BUG_SQE_ELEM(40, __u16,  buf_index);
+	BUILD_BUG_SQE_ELEM(40, __u16,  buf_group);
 	BUILD_BUG_SQE_ELEM(42, __u16,  personality);
 	BUILD_BUG_SQE_ELEM(44, __s32,  splice_fd_in);
 
@@ -10279,6 +10280,7 @@ static int __init io_uring_init(void)
 
 	BUILD_BUG_ON(ARRAY_SIZE(io_op_defs) != IORING_OP_LAST);
 	BUILD_BUG_ON(__REQ_F_LAST_BIT >= 8 * sizeof(int));
+
 	req_cachep = KMEM_CACHE(io_kiocb, SLAB_HWCACHE_ALIGN | SLAB_PANIC |
 				SLAB_ACCOUNT);
 	return 0;