btrfs: test balance and resize with an active swap file

Make sure we don't shrink the device past an active swap file, but allow
shrinking otherwise, as well as growing and balance.

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/177

@@ -0,0 +1,63 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2018 Facebook.  All Rights Reserved.
+#
+# FS QA Test 177
+#
+# Test relocation (balance and resize) with an active swap 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
+. ./common/btrfs
+
+rm -f $seqres.full
+
+# Modify as appropriate.
+_supported_fs btrfs
+_supported_os Linux
+_require_scratch_swapfile
+
+swapfile="$SCRATCH_MNT/swap"
+
+# First, create a 1GB filesystem and fill it up.
+_scratch_mkfs_sized $((1024 * 1024 * 1024)) >> $seqres.full 2>&1
+_scratch_mount
+dd if=/dev/zero of="$SCRATCH_MNT/fill" bs=1024k >> $seqres.full 2>&1
+# Now add more space and create a swap file. We know that the first 1GB of the
+# filesystem was used, so the swap file must be in the new part of the
+# filesystem.
+$BTRFS_UTIL_PROG filesystem resize 2G "$SCRATCH_MNT" | _filter_scratch
+_format_swapfile "$swapfile" $((32 * 1024 * 1024))
+swapon "$swapfile"
+# Add even more space which we know is unused.
+$BTRFS_UTIL_PROG filesystem resize 3G "$SCRATCH_MNT" | _filter_scratch
+# Free up the first 1GB of the filesystem.
+rm -f "$SCRATCH_MNT/fill"
+# Get rid of empty block groups and also make sure that balance skips block
+# groups containing active swap files.
+_run_btrfs_balance_start "$SCRATCH_MNT"
+# Shrink away the unused space.
+$BTRFS_UTIL_PROG filesystem resize 2G "$SCRATCH_MNT" | _filter_scratch
+# Try to shrink away the area occupied by the swap file, which should fail.
+$BTRFS_UTIL_PROG filesystem resize 1G "$SCRATCH_MNT" 2>&1 | grep -o "Text file busy"
+swapoff "$swapfile"
+# It should work again after swapoff.
+$BTRFS_UTIL_PROG filesystem resize 1G "$SCRATCH_MNT" | _filter_scratch
+
+status=0
+exit

tests/btrfs/177.out

@@ -0,0 +1,6 @@
+QA output created by 177
+Resize 'SCRATCH_MNT' of '2G'
+Resize 'SCRATCH_MNT' of '3G'
+Resize 'SCRATCH_MNT' of '2G'
+Text file busy
+Resize 'SCRATCH_MNT' of '1G'

tests/btrfs/group

@@ -179,3 +179,4 @@
 174 auto quick swap
 175 auto quick swap volume
 176 auto quick swap volume
+177 auto quick swap balance