btrfs: test swap file activation restrictions

Swap files on Btrfs have some restrictions not applicable to other
filesystems.

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

tests/btrfs/173

@@ -0,0 +1,56 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2018 Facebook.  All Rights Reserved.
+#
+# FS QA Test 173
+#
+# Test swap file activation restrictions specific to Btrfs, swap file can't be
+# CoW file nor compressed file.
+#
+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.*
+}
+
+. ./common/rc
+. ./common/filter
+
+rm -f $seqres.full
+
+_supported_fs btrfs
+_supported_os Linux
+_require_scratch_swapfile
+
+_scratch_mkfs >> $seqres.full 2>&1
+_scratch_mount
+
+echo "COW file"
+# We can't use _format_swapfile because we don't want chattr +C, and we can't
+# unset it after the swap file has been created.
+rm -f "$SCRATCH_MNT/swap"
+touch "$SCRATCH_MNT/swap"
+chmod 0600 "$SCRATCH_MNT/swap"
+_pwrite_byte 0x61 0 $(($(get_page_size) * 10)) "$SCRATCH_MNT/swap" >> $seqres.full
+mkswap "$SCRATCH_MNT/swap" >> $seqres.full
+swapon "$SCRATCH_MNT/swap" 2>&1 | _filter_scratch
+swapoff "$SCRATCH_MNT/swap" >/dev/null 2>&1
+
+echo "Compressed file"
+rm -f "$SCRATCH_MNT/swap"
+_format_swapfile "$SCRATCH_MNT/swap" $(($(get_page_size) * 10))
+$CHATTR_PROG +c "$SCRATCH_MNT/swap"
+swapon "$SCRATCH_MNT/swap" 2>&1 | _filter_scratch
+swapoff "$SCRATCH_MNT/swap" >/dev/null 2>&1
+
+status=0
+exit

tests/btrfs/173.out

@@ -0,0 +1,5 @@
+QA output created by 173
+COW file
+swapon: SCRATCH_MNT/swap: swapon failed: Invalid argument
+Compressed file
+swapon: SCRATCH_MNT/swap: swapon failed: Invalid argument

tests/btrfs/group

@@ -175,3 +175,4 @@
 170 auto quick snapshot
 171 auto quick qgroup
 172 auto quick punch
+173 auto quick swap