btrfs: test fstrim after doing a device replace

Test that after replacing a device, if we run fstrim against the filesystem
we do not trim/discard allocated chunks in the new device. We verify that
allocated chunks in the new device were not trim/discarded by mounting the
new device only in degraded mode, as this is the easiest way to verify it.

This currently fails on btrfs (since kernel 5.2) and is fixed by a patch
that has the following subject:

  "btrfs: fix filesystem corruption after a device replace"

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>

tests/btrfs/223

@@ -0,0 +1,71 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2020 SUSE Linux Products GmbH. All Rights Reserved.
+#
+# FS QA Test No. btrfs/223
+#
+# Test that after replacing a device, if we run fstrim against the filesystem
+# we do not trim/discard allocated chunks in the new device. We verify that
+# allocated chunks in the new device were not trim/discarded by mounting the
+# new device only in degraded mode, as this is the easiest way to verify it.
+#
+seq=`basename $0`
+seqres=$RESULT_DIR/$seq
+echo "QA output created by $seq"
+
+tmp=/tmp/$$
+status=1	# failure is the default!
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+_cleanup()
+{
+	cd /
+	rm -f $tmp.*
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+
+# real QA test starts here
+_supported_fs btrfs
+_require_scratch_dev_pool 3
+_require_command "$WIPEFS_PROG" wipefs
+
+rm -f $seqres.full
+
+_scratch_dev_pool_get 2
+_spare_dev_get
+dev1=$(echo $SCRATCH_DEV_POOL | $AWK_PROG '{ print $1 }')
+dev2=$(echo $SCRATCH_DEV_POOL | $AWK_PROG '{ print $2 }')
+
+_scratch_pool_mkfs "-m raid1 -d raid1"
+_scratch_mount
+_require_batched_discard $SCRATCH_MNT
+
+# Add a test file with some data.
+$XFS_IO_PROG -f -c "pwrite -S 0xab 0 10M" $SCRATCH_MNT/foo | _filter_xfs_io
+
+# Replace the first device, $dev1, with a new device.
+$BTRFS_UTIL_PROG replace start -Bf $dev1 $SPARE_DEV $SCRATCH_MNT
+
+# Run fstrim, it should not trim/discard allocated extents in the new device.
+$FSTRIM_PROG $SCRATCH_MNT
+
+# Unmount the filesystem.
+_scratch_unmount
+
+# Mount the filesystem in degraded mode using the new device and verify that the
+# mount succeeds and our file exists, with a size of 10Mb and all its bytes have
+# a value of 0xab.
+$WIPEFS_PROG -a $dev1 $dev2 >> $seqres.full 2>&1
+_mount -o degraded $SPARE_DEV $SCRATCH_MNT
+
+echo "File foo data:"
+od -A d -t x1 $SCRATCH_MNT/foo
+
+_spare_dev_put
+_scratch_dev_pool_put
+
+status=0
+exit

tests/btrfs/223.out

@@ -0,0 +1,7 @@
+QA output created by 223
+wrote 10485760/10485760 bytes at offset 0
+XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+File foo data:
+0000000 ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab
+*
+10485760

tests/btrfs/group

@@ -224,3 +224,4 @@
 220 auto quick
 221 auto quick send
 222 auto quick send
+223 auto quick replace trim