net: add accept helper not installing fd

stable inclusion
from stable-v5.10.162
commit ad0b0137953a2c973958dadf6d222e120e278856
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I6BTWC

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=v5.10.167&id=ad0b0137953a2c973958dadf6d222e120e278856



--------------------------------

[ Upstream commit d32f89da ]

Introduce and reuse a helper that acts similarly to __sys_accept4_file()
but returns struct file instead of installing file descriptor. Will be
used by io_uring.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Acked-by: David S. Miller <davem@davemloft.net>
Link: https://lore.kernel.org/r/c57b9e8e818d93683a3d24f8ca50ca038d1da8c4.1629888991.git.asml.silence@gmail.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Wang Weiyang <wangweiyang2@huawei.com>
Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com>