generic: test invalid swap file activation

Swap files cannot have holes, and they must at least two pages.
swapon(8) and mkswap(8) have stricter restrictions, so add versions
of those commands without any restrictions.

Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>

tests/generic/495

@@ -0,0 +1,77 @@
+#! /bin/bash
+# FS QA Test 495
+#
+# Test invalid swap files.
+#
+#-----------------------------------------------------------------------
+# Copyright (c) 2018 Facebook.  All Rights Reserved.
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it would be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write the Free Software Foundation,
+# Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+#-----------------------------------------------------------------------
+#
+
+seq=`basename $0`
+seqres=$RESULT_DIR/$seq
+echo "QA output created by $seq"
+
+here=`pwd`
+tmp=/tmp/$$
+status=1	# failure is the default!
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+_cleanup()
+{
+	cd /
+	rm -f $tmp.*
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+
+# remove previous $seqres.full before test
+rm -f $seqres.full
+
+_supported_fs generic
+_supported_os Linux
+_require_scratch_swapfile
+_require_test_program mkswap
+_require_test_program swapon
+
+_scratch_mkfs >> $seqres.full 2>&1
+_scratch_mount
+
+echo "File with holes"
+# We can't use _format_swapfile because we're using our custom mkswap and
+# swapon.
+touch "$SCRATCH_MNT/swap"
+$CHATTR_PROG +C "$SCRATCH_MNT/swap" >> $seqres.full 2>&1
+chmod 0600 "$SCRATCH_MNT/swap"
+$XFS_IO_PROG -c "truncate $(($(get_page_size) * 10))" "$SCRATCH_MNT/swap"
+"$here/src/mkswap" "$SCRATCH_MNT/swap"
+"$here/src/swapon" "$SCRATCH_MNT/swap"
+swapoff "$SCRATCH_MNT/swap" >/dev/null 2>&1
+
+echo "Empty swap file (only swap header)"
+rm -f "$SCRATCH_MNT/swap"
+touch "$SCRATCH_MNT/swap"
+$CHATTR_PROG +C "$SCRATCH_MNT/swap" >> $seqres.full 2>&1
+chmod 0600 "$SCRATCH_MNT/swap"
+_pwrite_byte 0x61 0 $(get_page_size) "$SCRATCH_MNT/swap" >> $seqres.full
+"$here/src/mkswap" "$SCRATCH_MNT/swap"
+"$here/src/swapon" "$SCRATCH_MNT/swap"
+swapoff "$SCRATCH_MNT/swap" >/dev/null 2>&1
+
+status=0
+exit