#! /bin/bash
# SPDX-License-Identifier: GPL-2.0
# Copyright (C) 2015 SUSE Linux Products GmbH. All Rights Reserved.
#
# FS QA Test No. btrfs/088
#
# Test that btrfs' transaction abortion does not corrupt a filesystem mounted
# with -o discard nor allows a subsequent fstrim to corrupt the filesystem
# (regardless of being mounted with or without -o discard).
#
# This issue was fixed by the following linux kernel patch:
#
#    Btrfs: fix fs corruption on transaction abort if device supports discard
#    (commit 678886bdc6378c1cbd5072da2c5a3035000214e3)
#
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()
{
	rm -f $tmp.*
}

# get standard environment, filters and checks
. ./common/rc
. ./common/filter

# real QA test starts here
_supported_fs btrfs
_require_scratch
_require_fail_make_request

SYSFS_BDEV=`_sysfs_dev $SCRATCH_DEV`

enable_io_failure()
{
	echo 100 > $DEBUGFS_MNT/fail_make_request/probability
	echo 1000 > $DEBUGFS_MNT/fail_make_request/times
	echo 0 > $DEBUGFS_MNT/fail_make_request/verbose
	echo 1 > $SYSFS_BDEV/make-it-fail
}

disable_io_failure()
{
	echo 0 > $SYSFS_BDEV/make-it-fail
	echo 0 > $DEBUGFS_MNT/fail_make_request/probability
	echo 0 > $DEBUGFS_MNT/fail_make_request/times
}

rm -f $seqres.full

# We will abort a btrfs transaction later, which always produces a warning in
# dmesg. We do not want the test to fail because of this.
_disable_dmesg_check

_scratch_mkfs >>$seqres.full 2>&1
_scratch_mount "-o discard"
_require_batched_discard $SCRATCH_MNT

# Create a file and call sync to commit our first transaction.
$XFS_IO_PROG -f -c "pwrite -S 0xaa 0 1M" $SCRATCH_MNT/foo | _filter_xfs_io
sync

# Create some other file, which forces a COW operation of the fs root, adding
# the old root location to the pinned extents list, and opens a new btrfs
# transaction.
touch $SCRATCH_MNT/bar

# Write to the first file to verify later that the original data extent was not
# a victim of a discard operation.
$XFS_IO_PROG -c "pwrite -S 0xbb 512K 1M" $SCRATCH_MNT/foo | _filter_xfs_io

# Now make sure the next transaction commit will abort and turn the fs readonly,
# unmount the fs, mount it again and verify we can open file foo and read its
# content, which should be what it had when the first transaction was committed
# (first call to sync), since btrfs is a COW filesystem and foo was not fsynced.
# Btrfs used to issue a discard operation on the extents in the pinned extents
# list, resulting in corruption of metadata and data, and used too to return the
# pinned extents to the free space caches, allowing future fstrim operations to
# perform a discard operation against the pinned exents. This made the fs
# unmountable because the btree roots that the superblock points at were written
# in place (by the discard operations).
enable_io_failure

# This sync will trigger a commit of the current transaction, which will be
# aborted because IO will fail for metadata extents (btree nodes/leafs).
sync
disable_io_failure

touch $SCRATCH_MNT/abc >>$seqres.full 2>&1 && \
	echo "Transaction was not aborted, filesystem is not in readonly mode"

# This fstrim operation should not cause discard operations to be performed
# against extents that were COWed, otherwise the next mount will fail since
# the btree roots that the superblock points at have their physical areas
# on disk full of zeroes.
$FSTRIM_PROG $SCRATCH_MNT

# We expect to be able to mount the fs again and have available all metadata and
# data that got persisted in the first transaction.
_scratch_cycle_mount

# We now expect file's foo content to match what it had when the first
# transaction was committed because the second transaction was aborted and we
# did not fsync foo.
echo "File foo content after transaction abort + remount:"
od -t x1 $SCRATCH_MNT/foo

status=0
exit