mainline inclusion
from mainline-5.4-rc1
commit dc617f29
category: bugfix
bugzilla: 50612
CVE: NA
---------------------------

Don't let userspace write to an active swap file because the kernel
effectively has a long term lease on the storage and things could get
seriously corrupted if we let this happen.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>

Conflict:
  include/linux/fs.h
  mm/filemap.c
Signed-off-by: Nzhangyi (F) <yi.zhang@huawei.com>
Reviewed-by: NYang Erkun <yangerkun@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Signed-off-by: NCheng Jian <cj.chengjian@huawei.com>