ovl: remove privs in ovl_fallocate()

stable inclusion
from stable-v5.10.169
commit 6618b0dcf265975555e3eb24183e2a9e9b1c947c
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7V9QX

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6618b0dcf265975555e3eb24183e2a9e9b1c947c



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

commit 23a8ce16 upstream.

Underlying fs doesn't remove privs because fallocate is called with
privileged mounter credentials.

This fixes some failure in fstests generic/683..687.

Fixes: aab8848c ("ovl: add ovl_fallocate()")
Acked-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: zhaoxiaoqiang11 <zhaoxiaoqiang11@jd.com>