zonefs: prevent use of seq files as swap file

zonefs: prevent use of seq files as swap file

commit 1601ea068b886da1f8f8d4e18b9403e9e24adef6 upstream.

The sequential write constraint of sequential zone file prevent their
use as swap files. Only allow conventional zone files to be used as swap
files.

Fixes: 8dcc1a9d90c1 ("fs: New zonefs file system")
Cc: <stable@vger.kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>