tests/generic/748

#! /bin/bash
# SPDX-License-Identifier: GPL-2.0
# Copyright (c) Meta Platforms, Inc. and affiliates.
#
# FS QA Test 748
#
# Repeatedly prealloc beyond i_size, set an xattr, direct write into the
# prealloc while extending i_size, then fdatasync. This is a regression test
# for a Btrfs crash.
#
. ./common/preamble
. ./common/attr
_begin_fstest auto quick log preallocrw dangerous

_require_scratch
_require_attrs
_require_odirect
_require_xfs_io_command falloc -k
[ "$FSTYP" = btrfs ] && _fixed_by_kernel_commit 9d274c19a71b \
	"btrfs: fix crash on racing fsync and size-extending write into prealloc"

# -i slows down xfs_io startup and makes the race much less reliable.
XFS_IO_PROG="$(echo "$XFS_IO_PROG" | sed 's/ -i\b//')"

_scratch_mkfs >> $seqres.full 2>&1 || _fail "mkfs failed"
_scratch_mount

blksz=$(_get_file_block_size "$SCRATCH_MNT")

# On Btrfs, since this is the only file on the filesystem, its metadata is at
# the end of a B-tree leaf. We want an ordered extent completion to add an
# extent item at the end of the leaf while we're logging prealloc extents
# beyond i_size after an xattr was set.
for ((i = 0; i < 5000; i++)); do
	$XFS_IO_PROG -ftd -c "falloc -k 0 $((blksz * 3))" -c "pwrite -q -w 0 $blksz" "$SCRATCH_MNT/file"
	$SETFATTR_PROG -n user.a -v a "$SCRATCH_MNT/file"
	$XFS_IO_PROG -d -c "pwrite -q -w $blksz $blksz" "$SCRATCH_MNT/file"
done

# If it didn't crash, we're good.

echo "Silence is golden"
status=0
exit