simple_recursive_removal(): kernel-side rm -rf for ramfs-style filesystems

mainline inclusion
from mainline-5.6-rc1
commit a3d1e7eb
category: bugfix
bugzilla: 24454
CVE: NA

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

two requirements: no file creations in IS_DEADDIR and no cross-directory
renames whatsoever.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Conflicts:
 fs/debugfs/inode.c
 fs/libfs.c
 fs/tracefs/inode.c
 include/linux/debugfs.h
 include/linux/fs.h
 include/linux/tracefs.h
 kernel/trace/trace.c
functional changes:
 replace current_time() with current_fs_time()
 remove call to fsnotify_rmdir() and fsnotify_unlink()

Signed-off-by: yu kuai <yukuai3@huawei.com>
Reviewed-by: zhangyi (F) <yi.zhang@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>