tests/generic/735

#! /bin/bash
# SPDX-License-Identifier: GPL-2.0
# Copyright (c) 2023 HUAWEI.  All Rights Reserved.
#
# FS QA Test No. 735
#
# Append writes to a file with logical block numbers close to 0xffffffff
# and observe if a kernel crash is caused by ext4_lblk_t overflow triggering
# BUG_ON at ext4_mb_new_inode_pa(). This is a regression test for
# commit bc056e7163ac ("ext4: fix BUG in ext4_mb_new_inode_pa() due to overflow")
# commit 2dcf5fde6dff ("ext4: prevent the normalized size from exceeding EXT_MAX_BLOCKS")

. ./common/preamble
. ./common/populate
_begin_fstest auto quick insert prealloc

if [[ "$FSTYP" =~ ext[0-9]+ ]]; then
	_fixed_by_kernel_commit bc056e7163ac "ext4: fix BUG in ext4_mb_new_inode_pa() due to overflow"
	_fixed_by_kernel_commit 2dcf5fde6dff "ext4: prevent the normalized size from exceeding EXT_MAX_BLOCKS"
fi

_require_odirect
_require_xfs_io_command "falloc"
_require_xfs_io_command "finsert"

dev_size=$((80 * 1024 * 1024))
_scratch_mkfs_sized $dev_size >>$seqres.full 2>&1

_scratch_mount
_require_congruent_file_oplen $SCRATCH_MNT 1048576	# finsert at 1M
file_blksz="$(_get_file_block_size ${SCRATCH_MNT})"

# Reserve 1M space
$XFS_IO_PROG -f -c "falloc 0 1M" "${SCRATCH_MNT}/tmp" >> $seqres.full

# Create a file with logical block numbers close to 0xffffffff
$XFS_IO_PROG -f -c "falloc 0 10M" "${SCRATCH_MNT}/file" >> $seqres.full
max_pos=$(( 0xffffffff * file_blksz ))
finsert_len=$(( max_pos - ((10 + 2) << 20) ))
$XFS_IO_PROG -f -c "finsert 1M ${finsert_len}" "${SCRATCH_MNT}/file" >> $seqres.full

# Filling up the free space ensures that the pre-allocated space is the reserved space.
nr_free=$(stat -f -c '%f' ${SCRATCH_MNT})
_fill_fs $((nr_free * file_blksz)) ${SCRATCH_MNT}/fill $file_blksz 0 >> $seqres.full 2>&1
sync

# Remove reserved space to gain free space for allocation
rm -f ${SCRATCH_MNT}/tmp

# Trying to allocate two blocks triggers BUG_ON.
$XFS_IO_PROG -c "open -ad ${SCRATCH_MNT}/file" -c "pwrite -S 0xff 0 $((2 * file_blksz))" >> $seqres.full

echo "Silence is golden"

# success, all done
status=0
exit